La sneaker elle-même est une refonte du coloris original "Silver Bullet" Air Max 97. Il est doté d'un Nike Homme réflecteur argenté et d'un maillage avec les lignes radiales caractéristiques du modèle et ajoute le drapeau portoricain à la boucle de la langue ainsi qu'à la semelle extérieure. Il semble également que la sneaker troque ses accents noirs traditionnels pour un bleu marine foncé.


Le style de chaussure unique Nike Air Max 97 "Puerto Rico" a été exposé pour la première fois Nike 2021 début mai. La conception globale de la chaussure ressemble à la palette de couleurs OG "Silver Bullets". Le drapeau de Porto Rico est injecté dans la langue comme étiquette et Aquí Me Quedo est ajouté à la semelle intérieure. Les mots I'll Stay Here reflètent l'esprit culturel et sont remplacés par une doublure intérieure, une semelle extérieure et un logo sur la languette bleu marine pour créer un style caribéen.


La base sur laquelle ces basketskrs marques sont cependant plutôt sobres, probablement pour que chacune puisse être facilement lue à une petite distance. Les nuances blanches reprennent le luminaire susmentionné ainsi que le maillage en dessous, la semelle intermédiaire, la doublure et la languette. Et bien qu'elle soit quelque peu audacieuse grâce aux lacets Volt et aux Swooshes, la palette est rapidement intégrée grâce à l'ombrage gris et réfléchissant de l'imprimé intégral.


À l'avant et au centre se trouve la plante de liège, visible à travers la fine broderie et l'applique sur la Nike Air Max 97 Cork Obsidian languette, tandis que le matériau de liège réel est utilisé sur l'une des voies supérieures de la silhouette emblématique de l'Air Max 97. Le rappel de la tige présente des matériaux en toile teinte, avec des coutures contrastées en beige pour ajouter à cette esthétique de plein air. Les semelles extérieures comportent également des grains de sable intégrés dans le caoutchouc pour étendre davantage l'approche organique.


https://www.basketskrs.com/

One of the most common uses of tarps and canvas is to protect furniture, carpets and other items while painting inside or outside. While canvas tarps are more expensive than disposable plastic tarps, they can be used over and over again. Canvas tarps are heavy and will stay in place without a lot of complicated taping and securing, and fit well over curved surfaces. They are usually less slippery than disposable plastic tarps, so they are also safer as there is less chance of injury due to falls.


Tonneau Covers Info [http://www.WetPluto.com/A-Look-at-Truck-...overs.html] provides detailed information on truck, hard, fiberglass, folding, retractable, vinyl, and discount tonneau covers.
There are various types of tarps such as Steel tarp, Hay tarp, Canvas tarp, Poly tarp, etc. Tarps are large strong sheets that are flexible and water-resistant. Different tarps are made up of different materials like canvas, polyester, polyethylene, etc. Tarps are multi-functional and are used for various purposes. They are used at a construction site to cover the debris or in a flatbed truck or trailer to protect the load that they are carrying. Canvas tarps are one such type of tarp that is used for covering the load carried on a flatbed trailer. They are used for certain kinds of the load because they are breathable and less abrasive. Normally every trucker keeps few canvas traps with them all the time just in case of emergencies. Canvas tarps are lightweight, affordable, and long-lasting. According to me, mytee products is a one-stop destination to buy the best quality canvas tarps. At here you will get the best quality tarps to satisfy all your flatbed needs.There are various types of tarps such as Steel tarp, Hay tarp, Canvas tarp, Poly tarp, etc. Tarps are large strong sheets that are flexible and water-resistant. Different tarps are made up of different materials like canvas, polyester, polyethylene, etc. Tarps are multi-functional and are used for various purposes. They are used at a construction site to cover the debris or in a flatbed truck or trailer to protect the load that they are carrying. Canvas tarps are one such type of tarp that is used for covering the load carried on a flatbed trailer. They are used for certain kinds of the load because they are breathable and less abrasive. Normally every trucker keeps few lumber tarps with them all the time just in case of emergencies. Canvas tarps are lightweight, affordable, and long-lasting. According to me, mytee products is a one-stop destination to buy the best quality canvas tarps. At here you will get the best quality tarps to satisfy all your flatbed needs.Canvas tarps can be used in different atmospheric conditions like heat, rain, or snow because they are breathable and water-resistant. They are mostly used in outdoor conditions to cover any kind of equipment or outdoor furniture. You can use these tarps at construction sites to cover and secure construction materials. Canvas tarps are also used to cover farming equipment because they can provide protection against rust. This eventually increases the life span of the logistics equipment. While you are transporting any product that needs to be fresh throughout the journey then canvas tarps are preferred over any other tarps. Canvas tarps are a good option if you want to protect any stationery load. However, canvas tarps should not be used for covering trailers or canopies because they have low tear strength at the seams. These tarps should also be avoided in high UV areas.
The tarp was used mainly at sea as a way to protect sailors and the items they transported across the seas. The original name for the tarp was the “tarpaulin.” This name came from combining the two words “tar” and “pall.” The pall was the fabric used by the sailors as a trailer cover.

1600-1900

The tarp moved inland. Many people used tarps for protecting items during travel, such as for covering wagons during moves. During the 1700s, the tarp became used for land travel as a tent covering. The waterproof surface of the tarp helped keep travelers and soldiers warm.

That's the bad news. The good news is that if you're using a rechargeable battery, you can make the chemical reactions run in reverse using a battery charger. Charging up a battery is the exact opposite of discharging it: where discharging gives out energy, charging takes energy in and stores it by resetting the battery chemicals to how they were originally. In theory, you can charge and discharge a rechargeable battery any number of times; in practice, even rechargeable batteries degrade over time and there eventually comes a point where they're no longer willing to store charge. At that point, you have to recycle them or throw them away.
All battery chargers have one thing in common: they work by feeding an electric current through batteries for a period of time in the hope that the cells inside will hold on to some of the energy passing through them. That's roughly where the similarity between chargers begins and ends!

The cheapest, crudest chargers use either a constant voltage or constant current and apply that to the batteries until you switch them off. Forget, and you'll overcharge the batteries; take the waterproof battery charger off too soon and you won't charge them enough, so they'll run flat more quickly. Better chargers use a much lower, gentler "trickle" charge (maybe 3–5 percent of the battery's maximum rated current) for a much longer period of time.

Slightly more sophisticated timer chargers switch themselves off after a set period, though that doesn't necessarily prevent overcharging or undercharging because the ideal charging time varies for all sorts of reasons (how much charge the battery held to begin with, how hot it is, how old it is, whether one cell is performing better than others, and so on). The best chargers work intelligently, using microchip-based electronic circuits to sense how much charge is stored in the batteries, figuring out from such things as changes in the battery voltage (technically called delta V or ΔV) and cell temperature (delta T or ΔT) when the charging is likely to be "done," and then switching off the current or changing to a low trickle charge at the appropriate time; in theory, it's impossible to overcharge with an intelligent waterproof car charger.
Nickel cadmium (also called "nicad" or NiCd), the oldest and perhaps still best known type of rechargeable batteries, respond best either to fairly rapid charging (providing it doesn't make them hot) or slow trickle charging.

Most people tend to put things on to charge "overnight" without paying too much attention to exactly what that means—but your batteries will work better and last longer if you charge them for the right number of hours. How long is that? It can be very confusing, especially if you use batteries that didn't come supplied with your waterproof marine charger. Never fear! All you have to do is read what it says on your batteries and you should find (often in tiny writing) the recommended charging current and charge times. If you have a basic charger, simply check its current rating and adjust the charge time accordingly. Bear in mind what we've said elsewhere about matching your charger to your batteries, however.
Lithium-ion rechargeable batteries are usually built into gadgets such as cellphones, MP3 players, digital cameras, and laptops. Typically they come with their own chargers, which automatically sense when charging is complete and cut off the power supply at the right time. Lithium-ion batteries can become dangerously unstable when the battery voltage is either too high or too low, so they're designed never to operate under those conditions. If the voltage gets too low (if the battery discharges too much during use), the appliance should cut out automatically; if the voltage gets too high (during charging), the electric transportation battery charger will cut out instead. Although lithium-ion batteries don't show a memory effect, they do degrade as they get older. A typical symptom of aging is gradual discharge for a period of time (maybe an hour or so) followed by a sudden, dramatic, and completely unexpected cut-out of the appliance after that. Read more about how lithium ion batteries work.

“It’s really taken off from no car monitor to tactile monitoring to taking a look at your eyes,” said Grant Courville, a vice president at BlackBerry QNX, which creates in-dash software systems. “I definitely see more of that coming as you get to Level 3 cars,” he added, referring to vehicles that can perform some self-driving functions in limited situations.The feature is part of the car’s Super Cruise system, the first hands-free driving tool to operate on select United States highways. The camera tracks a driver’s head position and eye movements to ensure that the person is attentive and able to retake control of the car when needed.

Automakers understand that tracking technology raises privacy issues, so BMW does not record or store the ahd car monitor information, Mr. Wisselmann said.
Affectiva collected a variety of driver information during the test, measuring elements like the amount of grip on the wheel, throttle action, vehicle dome camera, facial and head movements. It then compared that information with what was happening around the car to determine how much trust the driver had in the semi-autonomous system and the perceived level of cognitive load.

This scenario is closer to becoming reality than you may think, and although vehicle camra get all the headlines, most drivers will experience something like it long before they can buy a car that drives itself.

Full self-driving cars are taking longer to arrive than techno-optimists predicted a few years ago. In fact, in a financial filing Wednesday, Tesla acknowledged it may never be able to deliver a full self-driving car at all.

But with features such as automated cruise control, steering assist and automatic highway lane changing, new cars come loaded with driver-assist options. As they proliferate, the task of a human driver is beginning to shift from operating the vehicle to supervising the systems that do so.
That development carries promise and peril. Decades of research make clear that humans aren’t good at paying attention in that way. The auto industry’s answer: systems that monitor us to make sure we’re monitoring the car.

Such systems, usually relying on a driver-facing camera that car rear view monitor and head movements, already have been deployed in tens of thousands of long-haul trucks, mining trucks and heavy construction vehicles, mainly to recognize drowsiness, alcohol or drug use, and general distraction.

This valve controls the expulsion of oil from the spring side of the second gear band servo piston at speeds in the region of 60 km/h. The time period for oil to exhaust then depends upon the governor pressure varying the effective exhaust port restriction. Line pressure oil from the spring side of the second gear band servo piston passes through a passage leading to the 3–2 kickdown valve annular groove and from there to the 2–3 shift valve annular groove. Here some oil exhausts out from a fixed restriction while the remainder passes via a passage to the 3–2 control valve. As the vehicle speed approaches 60 km/h the governor pressure rises sufficiently to force back the 3–2 control valve piston, thus causing the wasted (reduced diameter) part of the control valve to complete the exhaustion of oil.

corrosion resistant control valve come in many forms: butterfly valve, ball and seat valve, disk-valve, piston-sleeve metering valve, and dart valve, to name but a few. Alumina has been used in many industrial valves. Water faucet valves of the standard disk-on-disk configuration are very common and are discussed in Section 12.2.8. Since they share almost all the same features of pump rotary valves.
With the single seated control valve lowered, the hydraulic pump is applied to bring the bottom plate of the mould to the lower limit. The separator is then lowered into the mould and fed with the shell and the inner core materials. The vibrator is switched on for 5 s to consolidate the content. The space created by consolidation is topped up. The vibrator is switched on again while the separator is extracted from the moulds. The top of the content of mould is flattened, and the mould lid closed and clamped. With the single seated balanced control valve raised, the hydraulic pump is engaged to stress the content to the desired compaction pressure, which was readable on the gauge. The mould lid is opened and with the control valve raised, the block is ejected from the mould.
The open tank and multi hole single seated control valve arrangement (Fig. 4) used here together with the 3% cavitation criterion in Fig. 2 is considered to be an industry-based and reliable method for determination of NPSHR in the pump best efficiency region, ISO [4]. More elaborate closed vacuum tank arrangements are used by pump manufacturers to establish NPSHR-curves for water. The measured NPSHR-values obtained here for water (Fig. 5) were about 10% larger than values from the GIW-pump curves. This means that the slurry NPSHR-results in Fig. 5 were about 1.5 times the water values from the pump curves. The scatter may represent the increased cavitation intensity of flow disturbances in an open tank system when compared to a closed tank arrangement.

Many LED lighting suppliers will say that full-spectrum LED grow lights are the best option for growing plants because they mimic the natural light from the sun. The argument goes:

“Plants have grown under sunlight for millions of years. Why would we want to change what mother nature knows is best?”

Well, we want to let you know that there is no such thing as a full-spectrum LED grow light.

There, we said it.

But before we get a flood of messages from concerned growers wondering what all the confusion is about, let’s first uncover what full spectrum means. Then we’ll let you in on the truth about full-spectrum LED grow lights so you can make the best grow light choice for your facility.

What is a Full-Spectrum LED Grow Light?
A full-spectrum LED grow light is simply a marketing term that implies that your grow light closely resembles light from the sun. This marketing term comes from the concept of “full-spectrum light,” which in recent years has been used to refer to electromagnetic radiation from the UV to infrared wavebands.

The History of the Full-Spectrum LED Grow Light
The full-spectrum commercial LED grow light is the newest evolution of an already confusing term. Originally, full-spectrum light described the only real full-spectrum light source, the sun.

Over time, the term began to take on other characteristics of sunlight. The commercial lighting industry began using the name “full-spectrum” to sell lights that produced a Color Rendering Index (CRI) over 90. Humans perceive colors more accurately under light sources with a CRI over 90, much like how we see colors in our natural world under daylight. This was a beneficial feature for human environments such as offices, outdoor spaces, and others.

With the advent of horticultural lighting, companies once again began to borrow the term. Only this time, they claimed that full-spectrum LEDs could reproduce the effects of sunlight for plants.

Thus, the full-spectrum LED grow light was born. Unfortunately, lighting for plants is not quite that simple.

Problems with Full-Spectrum LED Grow Lights
There are many issues with the concept of full-spectrum LED grow lights. For starters, just because you name something, doesn’t make it true. This rhetoric may have made sense for lighting designers interested in selling lights so humans could see, but plants require light to feed, grow, and live.

There are three major problems when talking about full-spectrum grow lights:

Full-Spectrum Grow Lights Aren’t Optimized for Plants
Full-Spectrum Grow Lights Don’t Include the Full Solar Spectrum
Full-Spectrum Grow Lights Are Not Dynamic Like the Sun
We’ll briefly look at these problems with full-spectrum grow lights one-by-one, so you can understand how deep the roots of this problem run:

1. Full-Spectrum Grow Lights Aren’t Optimized for Plants
A major problem with many full spectrum vertical grow light is that they are designed to give the appearance of daylight without being custom-tailored for rigorous plant growth.

It’s the reason why we at LumiGrow coined the phrase, “PAR is for plants and Lumens are for humans.” Not all wavelengths of light are optimal for photosynthesis. Plants photosynthesize electromagnetic radiation in the 400 to 700 nanometer range, known as Photosynthetically Active Radiation or PAR. So, plants don’t care how bright your light fixture appears to you.

Still, most full-spectrum lighting companies build fixtures with this visual appeal in mind.

When you hear that the diodes in your full spectrum grow light are 3,000k to 4,500k, or 5,000k+, this degree of Kelvin (K) refers to how “cool” or “warm” your light is in appearance.

Our understanding of plant photobiology has come a long way. We understand much more about plants than to be using human lighting metrics to design our grow lights.

Our goal as growers is to improve the lighting characteristics most important for plant growth. This means not only getting enough PAR light, but also the right mix of light spectra, which brings us to problem #2.

The thinking behind many full spectrum LED grow lights on the market is that by creating a spectral distribution similar to sunlight, your plants will grow well. A decent theory, except that full spectrum grow lights are not actually similar to the sun.

We can see below that the sun’s radiation includes much more than the visible or PAR wavebands.

Sunlight itself is complex, and many scientists are still working to understand it today. You can see that sunlight also contains ultraviolet (UV) and infrared light (as well as x-rays, radio waves, and others, but we’ll leave those alone for now).

Although PAR is the most important light for photosynthesis, plants still respond to radiation outside of the PAR spectrum. For instance, UV light elicits protective compounds in plants similar to the way humans become tanned in the presence of UV.

Plants also use a type of infrared light called “far-red light” to induce a shade avoidance response, causing them to stretch and can induce early flowering.

To create a light source that elicits plant response the same way the sun does would be too costly and downright impossible given current grow light technology. Nor would you want to create such a grow light, which takes us to problem #3.

3. Full-Spectrum Grow Lights Are Not Dynamic Like the Sun
Not only would it be too costly to create an actual full spectrum quantum board grow light, but if such a thing even existed, its performance would still not accurately reflect what’s happening in nature.

The sun’s spectrum is in constant flux due to changes in weather or its position in the sky relative to earth. In the graphic above, you can see how sunlight spectra change throughout the day or in different weather conditions.

Because of this phenomenon, it’s best to think about the interaction between sunlight and plants as a continually changing process.

If you hang your full spectrum grow lights in a greenhouse, you will still reap the benefits (and disadvantages) of this natural process from the sun. But if you take those same full-spectrum lights and hang them indoors, they will not behave like the sun.

Photomorphogenic responses by plants are co-regulated, which means that certain expressions of the plant may turn on or off based on the amount of light within one waveband relative to another.

Photosynthesis depends upon the absorption of light by photoreceptors and pigments in the leaves of plants. The most well-known of these pigments is chlorophyll-a, but there are many accessory pigments that also contribute to photosynthesis.

The relative light absorption of chlorophyll pigments as shown in the graph to the right is one of the reasons why red light has become popular among LED grow lights. Not all PAR light contributes to photosynthesis equally, though we now understand that other wavebands of light such as green, do play an important role in this process.

Since photoreceptors in plants also have their own ranges for light absorption, they co-regulate processes that create plants’ form and structure depending on the spectral mix they receive.

For instance, higher ratios of blue light can induce more robust root growth, more favorable plant biochemistry, and a hardier structure. But these effects may not be as pronounced when more red light is introduced.

Thus, the ever-changing spectrum of the sun is constantly signaling to plants to change their form and structure based on the natural conditions of the environment.

But before you rush and begin moving your grow room outdoors, let’s consider why plants don’t need the full spectrum of sunlight. For starters, plants don’t need UV or infrared light to live. Also, in a controlled environment, plants are given ideal conditions to grow in and often don’t need to compete with other species to live.

Plants only require light in the 400 to 700-nanometer range to photosynthesize. So, you’ll want to choose a grow light that produces your desired results, most often higher yields and better quality for your plants.

What is the Best Light Spectrum for Plant Growth?
By now you must be wondering:

“If I can’t mimic sunlight, then what light spectrum should I use?”. The answer is both simple and quite complex.

Plants only require PAR light for photosynthesis. So, if your grow light is optimized within the PAR spectrum, you’re going to get the most bang for your buck when it comes to minimizing electrical costs while maximizing plant health.

Beyond PAR, it’s important to choose a light spectrum that’s:

best for the environment you’re growing in (greenhouse or indoors)
tailored to your plant’s growth phase (propagation, vegetative, flowering, or finishing)
or specific to the cultivar being grown
Full Spectrum LED Grow Lights vs. Other Grow Light Options
It should be clear by now that there are no real standards around full samsung lm301b grow light. Full-spectrum is simply a term used to sell you a simple idea.

Although you cannot mimic sunlight, you can use light spectrum to your advantage.

Luckily, there are many grow lights available with designs intended to do just that. So, let’s uncover your options so you can pick the best grow light for your cultivation.

Narrow Spectrum LED Grow Lights
Narrow-spectrum LED grow lights use a higher ratio of narrow-band LEDs. These grow lights most often have a pink or purplish hue since they are optimized for the blue and red PAR wavebands.
These types of pink grow lights have been popular since the early days of LEDs for horticulture. Though this doesn’t mean they are outdated by any means.

In greenhouse environments a narrow spectrum is almost always desired. The sun already fills out a full spectrum, so it makes sense to put most of your energy into wavelengths that are most optimal for photosynthesis.

Also, because of the added efficiency of red diodes versus other colors, you will get more bang for your buck when it comes to energy efficiency.

Broad-Spectrum LED Grow Lights
Broad-spectrum LED grow lights have a higher ratio of broad-band LEDs. These lights are white in appearance, though there are no actual white wavelengths. The white hue is a mix of blue, red, and green wavebands.

These grow lights also don’t claim to mimic the sun, but they will effectively replace the sun to drive high yields and premium quality in any environment.

Our broad-spectrum has been enriched with red and blue peaks to drive robust photosynthesis and plant structure while emphasizing the green waveband to be versatile with any crop type or cultivation environment.

Recommended for indoor environments, except in specialized cases where narrow-band lighting is preferred.

Adjustable Spectrum LED Grow Lights
These modern LED grow lights allow for precision control of your plants. By adjusting your grow light spectrum wirelessly, it’s possible to speed up flowering times, improve your plant’s biochemistry, or customize your plants’ structure to root better and be more easily managed.

Here at the Strategist, we like to think of ourselves as crazy (in the good way) about the stuff we buy, but as much as we’d like to, we can’t try everything. Which is why we have People’s Choice, in which we find the best-reviewed products and single out the most convincing ones. (You can learn more about our rating system and how we pick each item here.)

And while we’ve written about lots of landscaping gear before — including garden hoses and leaf blowers — here, we’ve rounded up the best garden tillers as praised by the most enthusiastic reviewers on Amazon. 

More than 40 percent of reviewers describe this electric garden tiller as powerful. One reviewer, who used this on a flower bed that hadn’t been tended to in decade, said, “It powered through everything, the roots of old rosemary shrubs, weed stems, larger chunks of old mulch, it ground them all up and dug deep into the dirt and mixed it all up nice.” Another reviewer, working with hard clay soil, writes, “It practically cut through concrete and was able to go to a depth of 6-8.” But reviewers with soft soil like it too: “The soil itself was fairly soft and unchallenging, but even at that, I was shocked at how quickly this tiller busted it up into a surprisingly fluffy soil.” Many also say it’s easy to operate and appreciate that it comes almost completely assembled. Plus, it’s electric, which is a huge selling point for many. “Unlike my gas ones though, it’s easy to turn it off, and it actually starts right back up again, doesn’t stink, and you don’t run out of gas halfway through … so far has made short, albeit back breaking, work of tilling up my garden,” explains one reviewer. The only fear one reviewer has is that it has “almost has too much power, so you have to be careful when you hit a rock or thick root as you can break a tine or overheat the motor; but the quick release stop works great.”

“I didn’t have high expectations for this product considering its low price, it being electric, and the toughness of the dirt where I live,” writes one reviewer, but their fears were eased once this tiller arrived. “As soon as I pressed the power button, this thing took off like a rocket. I live in north Georgia, right at the North Carolina line and our soil here isn’t all that friendly when it comes to landscaping or digging because of the thick red clay and large natural stones. This tiller dug in without any issue.” And much like our best-rated tiller, this one from Earthwise also gets a lot of praise for its smaller size, especially for those with small gardens or flower beds. “Used this to till for a 20x20 foot wildflower plot,” one reviewer writes. “Did a great job of cutting through the fairly thin turf and the clay soil, tilling down a few inches.” Another says, “It was very easy to put together and has just the right amount of power needed in a flower bed.” And one says, “There is enough power to even work through the hard clay we have.” The flip side, however, is that “It takes more passes than a full size tiller because it is small, but overall I still think it was easier because it is just so easy to use.”

“This thing really is the little roto-tiller that could,” one reviewer writes of this Sun Joe machine. “We have VERY heavy clay soil that is full of rocks/stones and roots ranging from pencil thickness to several inches in diameter. This bad boy took it all on no problem. It simply chucks the rocks out of the way.” And though it looks like a toy, one reviewer swears, “This machine is a BEAST. I tilled up a hundred square feet of rock-hard ground that is a clay and river cobble mixture to a depth of six to eight inches in short order.” Many say this is also the ideal tiller for a small garden. “My vegetable garden is about 20 by 35, it is a rear tine tiller for something around that size,” one says, while another used it to till their 360-square-foot “garden area in an hour or less.” And while many reviewers prefer electric tillers to gas ones because they don’t require multiple cranks to start up and you don’t have to fuss with mixing gas and oil to fuel it, one downside is needing to plug in with a cord. However, it’s not a dealbreaker. As one reviewer explains, “The cord is a pain, but I have found a way to control it and don’t have to worry about having enough gas in the gas cans.”

This Sun Joe electric garden tiller is nearly the same as the one previously mentioned, but it’s got a slightly more powerful motor with 13.5 amps, rather than 12. And according to one reviewer, “No regrets paying more for the 13.5 amp motor.” They describe it as a beast, explaining, “My backyard had a mulched area that was kept in disarray by the previous owner. I wanted to get rid of the iris, weed and other undesirable plants. This tiller shredded the area pulling out the weed and the roots.” Others agree that the extra power gets any size job done. “I tilled ground that was clay and compacted with rocks, buried pieces of wood, fabric pieces decomposing, beer bottles,” one writes, adding, “The tiller cut through this like butter.” Another says, “I did an area about 40x25 in no time on our first nice day, and it never lacked for power.” And even though it packs a punch, it is still easy to handle, according to more than a quarter of reviewers. One reports it “handles as easily as a vacuum cleaner albeit more bouncy.” One word of warning, since this tiller is not cordless: You’ll need “AT LEAST a 14-gauge extension cord … Long runs over 50-feet will need 12-gauge which isn’t cheap but nice cables to have anyways.”

While reviewers admit this tiller isn’t powerful enough to break through new ground, they do say it’s ideal for mixing up soil in their flower beds. “I have 200 sq ft of 4x4 raised beds and this is perfect for turning over the soil in the whole box or just a space between plants,” says one reviewer. Another who calls this “a kitchen mixing machine for the soil” says, “It’s not a tractor, it instead is great for breaking up soil in one spot, like if you want to plant something like a rose bush and you need to break up the soil and/or mix in soil amendments.” Another compares it to an egg-beater, because “it loosens dirt adequately to about a 4-inch depth and keeps me off my aging knees.” The fact that it’s cordless keeps this tiller lightweight and easy-to-operate, too. Reviewers say batteries last between 30 minutes and an hour, enough for these smaller projects, though one reports that one charge “made it for 2+ thorough passes of a 15X3 ft space.”

“This little machine will dig to China if you let it,” says one reviewer, and 75 percent of reviewers give this Mantis gas tiller five stars. One reviewer, with “decades of experience with Mantis tillers,” says, “You really can convert an established lawn into a plantable bed without first scraping off the sod” with this thing. Another says that despite the power, it’s still “very easy to make it till or cultivate.” They continue, “Rocks I couldn’t see did not stop this mean machine.” And while some note it works in their small gardens, others have taken this to their entire backyard: “We did an entire backyard border with the Mantis tiller and it did an amazingly excellent job of prepping the soil. It was powerful, dug deep for planting shrubs and whatever we wanted. Cleaning it is a breeze and its light weight makes it very enjoyable to use.” As for fuel, one user says, “I can till my entire garden on less than a tank.”

“It is light, but, man, does it dig in,” one reviewer says of this four-cycle gas tiller. One says it’s “Great for gardening, installing landscaping beds, trenching for rock borders, Hell, I even used mine to dig a 3-foot deep trench for a drain-tiled downspout.” The main advantage of this four-cycle tiller, compared to the two-cycle above, is that it doesn’t require a mix of oil and gas. That means the set-up is pretty quick. “Thirty minutes out of the box to tines in the ground. Oiled, gassed up, and primed, it started on the second pull; bonus, it’s quiet,” one reviewer writes. Another says it “has the torque and ease of operation wrapped into one unit,” and others say it also offers more control. “It really digs in when tilling and In an established garden, you can get right in around your plants without destroying half the garden.”
Bob Crewe is an expert on garden tillers, but when he needed one at his suburban Chicago home, he rented it.

That's about to change.

"This might be the season when I finally pick one up," said Crewe, who works for Power Equipment Direct, an online home equipment store. "If you already have one waiting for you, you're more apt to go out and get to it."

The advantages of owning or renting a mini tractor -- or its smaller cousin, a cultivator -- are many.

Tillers and cultivators are useful for turning soil, mixing in compost and fertilizer for soil amendment and loosening soil to help water reach plant roots.

Gardeners are firing up their tillers now to prepare flower beds and vegetable gardens for planting. This year's early spring has brought strong demand for tillers, said Joseph Cohen, CEO of Snow Joe, a garden equipment company headquartered in Edison, N.J.

"No one expected to be in the garden this early. I've never seen demand this early," Cohen said.

In summer, tillers and cultivators can weed between vegetable rows, said Barbara Hastings, senior manager of marketing and communication for Troy-Bilt brand of outdoor equipment. The company is headquartered in Valley City.

Come fall, tillers plough garden waste back into the soil to decompose over the winter, Hastings said.

Many homeowners like to rent a tiller just for a few hours, and let someone else deal with maintenance and storage. Fees at tool rental companies can run from $29 for a two-hour rental of a small tiller up to $85 for a 24-hour rental of a large unit. Rental companies typically ask for a deposit.

But, when you rent a tiller, transportation is your headache. That means lifting a heavy unit in and out of the car, and protecting the car trunk from dirt and mud, Crewe said. You may also need to wash and dry the tiller before returning it.

If you rent a tiller every year, the fees will soon equal what a new tool would cost. Plus, owning a tiller means no more working with one eye on the clock.

Flowers are harvested with sharp knives or electric pruning shear. On standard carnations two to three nodes and on spray carnations three to four nodes are left on the shoots for the next flowering. Flowers should be cut in the early morning when plants are turgid. Standard carnations are harvested as open flowers or in the bud stage. Spray carnations are harvested with two flowers open and the rest showing color. Flowers are handled carefully to avoid breakage and bruising. It is important to expose flowers to a 40° to 48°F environment as soon as possible to reduce plant temperature. Precooling the flowers maintains quality and increases longevity.

Above all else, investment in a pair of high-quality pruning shears is mandatory. One manufacturer even has a special hand grip designed for left-handed people, swivel handles and a model with blade removal for maintenance. For miniature roses, there are smaller versions of these pruning shears which rely on a smaller, straight-edged blade surface. For removal of large woody canes at the bud union, a pruning saw will allow access for flush removal. Attempts to use pruning shears for these jobs usually result in damage to the bud union. It is best to approach cane removal with a proper saw designed specifically for the job. For cutting large-diameter canes a pair of lopping shears with 30- or 45-cm handles can facilitate the cutting without placing too much pressure on the hands. Again, attempts to cut large-diameter canes with pruning shears will require a lot of extra strength. Lopping shears with long handles solve the strength problem and make the cut clean and sharp. Invest in a small wire brush (about 5 cm wide by 75 cm deep) to help remove loose bark from the bud union. Such treatments can often encourage basal breaks and stimulate new growth since growth often finds it impossible to break through the heavy tree-like bark encountered on older bushes. Finally, save on profanities while pruning by buying a good strong pair of leather gauntlet gloves or hand gloves that are puncture-proof. There is nothing as irritating as a thorn under the nail to cause a string of words rarely heard in a rose garden!

Harvesting is done manually when the capsules are dry at the ends of the branches. Pruning shears are used to cut branches and also remove inflorescence containing 15–20 capsular fruits. Once harvested, the fruit are carried in baskets to a land or a warehouse where, after drying, they will be processed in specific equipments or manually. The machines separate the capsules from the seeds and classify them for subsequent packing in polyethylene bags, where they remain preserved for more than five years in perfect condition without any plant protection treatment (Cruz et al., 2008).

Human beings disseminate all kinds of pathogens over short and long distances in a variety of ways. Within a field, humans disseminate some pathogens, such as tobacco mosaic virus, through the successive handling of diseased and healthy plants. Other pathogens are disseminated through tools, such as portable mini electric garden shears, contaminated when used on diseased plants (e.g., pear infected with fire blight bacteria), and then carried to healthy plants. Humans also disseminate pathogens by transporting contaminated soil on their feet or equipment, using contaminated containers, and using infected transplants, seed, nursery stock, and budwood as mentioned previously. Finally, humans disseminate pathogens by importing new varieties into an area that may carry pathogens that have gone undetected, by traveling throughout the world, and by importing food or other items that may carry harmful plant pathogens. Examples of the role of humans as a vector of pathogens can be seen in the introduction into the United States of the fungi causing Dutch elm disease and white pine blister rust and of the citrus canker bacterium, in the introduction in Europe of the powdery and downy mildews of grape, and, more recently, in the rapid spread of sorghum ergot almost throughout the world (Fig. 2-20).

The primary fungi of an ambrosia beetle are abundant in a gallery only when larval stages are present (Kajimura and Hijli 1992). Thus, the best isolates of primary fungal symbionts can be made a month or two after initial infestation. Galleries are exposed by sawing thin sections from the infested bole. It is important to work as quickly and as aseptically as possible, using alcohol-flamed saws, wood chisels, and/or pruning shears. Adult insects can be removed, and visible fungal growth within the several-millimeter-diameter gallery can be isolated using sterile fine forceps. Thin slices or chips of galleries should be preserved, dried, and mounted, or mounted directly on slides with fixative mounting medium, such as lactophenolaniline blue, for later study.

Ambrosia fungi in the genus Corthylus and most Xyleborus species generally form a thick, whitish palisade layer on the walls of galleries if eggs and/or larvae are present. That fungal growth can be isolated easily by streaking or spot plating on isolation media (see next section on “Culture”).

Fungal growth usually is not so evident on the gallery walls or larval cradles of xylomycetophagous insects; thus, small slices and chips of wood should be removed aseptically for plating. Slices or fragments of galleries can be placed aseptically in a sterile moist chamber (Appendix I) to encourage fungal growth in the absence of actively feeding larvae, so that primary ambrosia fungi can be isolated, often within a few days, before contamination from saprobic fungi.

Live beetles trapped in flight or taken from galleries are difficult to handle because of their small size and smooth cylindrical shape. A simple vacuum apparatus consisting of a sterile micropipette tip with a small aperture attached to a rubber hose fixed to a vacuum pump or vacuum line allows one to pick up individual beetles and transfer them easily from dish to dish or to sterile glass slides for dissection.

Beetles can be surface disinfected to reduce the presence of nonmycangial microbes by washing in sterile 0.1% HgCl2 solution or dilute sterile bleach (NaHCl2) for 2–4 minutes, followed by several rinses in sterile water. Investigators can also free adult beetles of external nonmycangial microbes by placing them alternately in plates of sterile wet filter paper for 18 hours and then on dry sterile filter paper for 6 hours. Several transfers typically remove most external microbes. Individual beetles can be stored on sterile moist filter plates for months at refrigerator temperature until needed for dissection and isolation. Prevention of dehydration appears to be the critical factor for keeping them alive during long-term storage.

The process of harvesting in Stevia is very important to obtain the highest leaf biomass yield with the most desirable quality and quantity of the sweet compound of steviol glycosides with a desirable taste. The time to harvest Stevia crop varies dependent on the place and time. The first harvest generally can be done 4 months after cultivation and the subsequent harvest is suggested to be done once every 3 months or 40–60 days later. Generally, three commercial harvests can be done every year. Optimum biomass and steviol glycoside quality and quantity can be obtained at the stage of flower bud initiation. It is suggested to cut the branches about 5.0 cm above the ground with tree branches powered pruning shears before stripping the leaves. As the tips of the stems contain as much steviol glycoside as the leaves, they can be added to the harvest yield. It is recommended to cut the stems leaving about a 10 cm portion above the ground to induce the emergence of new flushes, for the subsequent harvest (Kassahun et al., 2013). Benhmimou et al. (2017) reported that the optimal yield depended on the harvesting time and the yield of summer harvesting (August) was higher than that of autumn harvesting (October).

One of the important processes after crop harvesting is drying the Stevia leaves in the best way. The herb should be immediately dried after harvesting by placing on a net or screen. The plants can be dried in full sun, shade, or by passing hot dry air over the plant leaves. This drying process with heat lasts for 24–48 h to obtain completely dry leaves at 40°C–50°C. It should be noted that excessive heat or longer drying time could lower the stevioside level of dried leaves. A dehydrator machine can also be used to dry the Stevia leaves (Singh et al., 2014; Zewdinesh et al., 2014). Samsudin and Aziz (2013) reported that the quality of Stevia leaves dried in a hot air dryer at 50°C temperature for 6 h was better in terms of sweetness, nutrient content, and color of leaves. After applying any of the drying methods, the dry leaves should be packed and stored in a dry and cool place for further utilization (Zewdinesh et al., 2014).

Azaleas are pinched to increase shoot numbers, plant size, floriferousness, and also as a mechanism for timing flowering. The first mentioned reasons will be discussed in this section on vegetative development, while the use of pinching to schedule flowering will be considered in the section on flowering.

The final size of azalea plants will be largely determined by the number of times plants are pinched, if growing conditions are satisfactory. In many places, azaleas are only pinched once each year, but the plants could be pinched every 3 to 4 months if faster increases in size were desired. This can only be done under protected conditions or in climates where low temperatures are not encountered. The expenses encountered in indoor culture must be considered, but new vegetative growth could always be occurring under the proper environmental conditions. A night temperature of 65°F and long days will enhance vegetative growth. Fertilization programs would have to be more precise than under conditions where plants are only pinched once annually. Carbon dioxide injection has also been suggested for maximum growth.

Pinching can be done manually or chemically, but most plants are pinched with powerful battery operated pruning shears or electric clippers. Some propagators use the pinch as a way to get cuttings so the plants serve dual roles as stock plants and eventually as flowering plants. If such a practice is followed then the pinch involves the removal of shoots about 3 to 4 inches long. If cutting production is not an objective of pinching, then only the tips of the shoots need to be removed. More leaf axils then remain, so one might expect more lateral shoots than when a harder pinch is made.

There are different chemicals that have been used to pinch azaleas. The fact that azaleas are multibranched plants makes chemical pinching worthwhile. Fields of azaleas that might require weeks to be pinched can be chemically pinched in hours, so labor costs are significantly reduced. The crop will be more uniform in development as well, as all plants are pinched at the same time.

Off-Shoot-O was the first chemical pinching agent of economic importance (Stuart, 1967, 1975) but its use has declined. Effectiveness of Off-Shoot-O is influenced by temperature, relative humidity, stage of apex development, and cultivar. The chemical works by physically damaging the apex, and the material has to come in contact with the apex for pinching to occur. One can tell within about 24 hours if shoot tip damage has occurred.

Dikegulac (Atrimmec) was the second prominent chemical pinching agent. Its mode of action is biochemical, so the chemical does not have to come in direct contact with the apex. The material is translocated through the phloem, and DNA synthesis is affected (Bocion et al., 1975; de Silva et al., 1976). It is not affected as much by the factors that influence the effectiveness of Off-Shoot-O (Larson, 1978). The effectiveness of Atrimmec cannot be determined until at least 2 weeks after its application. Lateral shoot initiation and development are delayed compared to those on plants that are manually pinched, and new leaves are often very narrow. Some azalea growers do not use Atrimmec alone, but prune the large, long shoots to get the desired plant shape, break apical dominance, and then apply Atrimmec 2 days later to stimulate lateral branching.

Other new chemicals are being tried, but EPA label clearance is lacking at this time.

Every mycologist has his or her preferred collecting paraphernalia, and to a degree preferences depend on the taxa being collected. At least four items are required for collecting macrofungi: (1) a tool for cutting and digging, (2) a container or wrapping material for each specimen, (3) a larger container for transporting specimens in the field and back to the lab, and (4) a label for each specimen.

A thick-bladed, moderately sharp knife can be used to cut woody substrata or dig in soil. Some collectors carry both a knife and a trowel for collecting sporocarps from soil. Different types of fungi occurring on wood require different types of collecting equipment. An ax or hatchet often is needed to extract wood to a depth sufficient to enable identification of the host if it is unknown. However, a mallet and wood chisel, a heavy sheath knife, or a folding knife with a locking blade are usually sufficient for removing the fungus. A pair of electric bypass pruning shears and a folding pruning saw are also helpful for cutting smaller diameter twigs and branches to a uniform length. Care must be used to avoid undue damage to the plant if collecting from a living tree (Figs. 8.10 and 8.11).

Peptides are smaller versions of proteins. Many health and cosmetic products contain different peptides for many uses, such as their potential anti-aging, anti-inflammatory, or muscle building properties.

Recent research indicates that some types of peptides could have a beneficial role in slowing down the aging process, reducing inflammation, and destroying microbes.

People may confuse peptides with proteins. Both proteins and peptides are made up of amino acids, but steroids powder contain far fewer amino acids than proteins. Like proteins, peptides are naturally present in foods.

Due to the potential health benefits of peptides, many supplements are available that contain peptides that manufacturers have derived either from food or made synthetically.

Some of the most popular peptides include collagen peptides for anti-aging and skin health, and creatine peptide supplements for building muscle and enhancing athletic performance.

In this article, we discuss the potential benefits and side effects of peptide supplements.

Peptides are short strings of amino acids, typically comprising 2–50 amino acids. Amino acids are also the building blocks of proteins, but proteins contain more.

Peptides may be easier for the body to absorb than proteins because they are smaller and more broken down than proteins. They can more easily penetrate the skin and intestines, which helps them to enter the bloodstream more quickly.

Scientists are most interested in mechano growth factor peptide, or those that have a beneficial effect on the body and may positively impact human health.

Different bioactive peptides have different properties. The effects they have on the body depend on the sequence of amino acidsTrusted Source they contain.

Some of the most common peptide supplements available are:

Collagen peptides, which may benefit skin health and reverse the effects of aging.
Creatine peptides, which may build strength and muscle mass.
Some people may take other peptides and peptide hormones to enhance athletic activity. However, the World Anti-Doping Agency have banned many of these, including follistatin, a peptide that increases muscle growth.

Collagen is a protein in the skin, hair, and nails. Collagen peptides are broken down collagen proteins that the body can absorb more easily. Taking collagen peptides may improve skin health and slow the aging process.

Some studiesTrusted Source indicate that dietary food supplements that contain collagen peptides can treat skin wrinkles. Other research indicates that these supplements may also improve skin elasticity and hydration.

Peptides may stimulate the production of melanin, a skin pigment, which may improve the skin’s protection against sun damage.

Topical anti-aging cosmetics can also contain Melanotan Peptide, which manufacturers claim can reduce wrinkles, help skin firming, and increase blood flow.

Improve wound healing
As collagen is a vital component of healthy skin, collagen peptides may facilitate faster wound healing.

Bioactive peptides can also reduce inflammation and act as antioxidants, which can improve the body’s ability to heal.

Research is currently ongoing into antimicrobial peptides, which may also improve wound healing. Having very high or very low levels of some antimicrobial peptides may contribute to skin disorders, such as psoriasis, rosacea, and eczema.

Prevent age-related bone loss
Animal research links a moderate intake of collagen peptides with an increase in bone mass in growing rats who also did running exercise.

The study may point to collagen peptides being a useful way to counteract age-related bone loss. However, more research is necessary, especially on humans.

Build strength and muscle mass
Some researchTrusted Source on older adults indicates that collagen peptide supplements can increase muscle mass and strength. In the study, participants combined supplement use with resistance training.

Creatine peptides may also improve strength and help to build muscle.

While fitness enthusiasts have been using creatine protein powders for many years, creatine PEG MGF peptide are increasing in popularity.

These particular peptides may be easier for the body to digest, which means they may cause fewer digestive problems than creatine proteins.

For healthy individuals, peptide supplements are unlikely to cause serious side effects because they are similar to the peptides present in everyday foods.

Oral peptide supplements may not enter the bloodstream as the body may break them down into individual amino acids.

In one studyTrusted Source where females took oral collagen peptide supplements for 8 weeks, the researchers did not note any adverse reactions.

However, the United States Food and Drug Administration (FDA) do not regulate supplements in the same way they do medications. As a result, people should exercise caution when taking any supplements.

Topical creams and ointments containing peptides may cause skin symptoms, such as skin sensitivity, rash, and itching.

Individuals should always buy from a reputable company and discontinue use if adverse reactions occur.

Also, it is a good idea to speak to a doctor before taking peptide supplements or using topical products that contain peptides.

Those who are pregnant, breastfeeding, taking medications, or living with a medical condition should avoid using peptides until they speak to their doctor.
The timing and dose of peptide supplements will vary, depending on the type and brand.

Always follow the package instructions when taking peptide supplements or using topical peptide creams or lotions. Never exceed the recommended serving size. Discontinue use and consult a doctor if adverse reactions occur.
Peptides are naturally present in protein-rich foods. It is not necessary to take peptide supplements or use topical sources of peptides.

However, some people may wish to use collagen peptides with the aim of slowing down the aging process. Others may take creatine peptides to build muscle and strength.

There is still limited evidence to indicate that these products are effective, and much more research is necessary to assess their efficacy and safety thoroughly.

Research into peptides is in the early stages, and in the future, scientists may discover health benefits of different types of peptides. Until then, people should exercise caution when taking any supplement and discuss the potential benefits and risks with their doctor beforehand.

Protein–protein interactions (PPIs) execute many fundamental cellular functions and have served as prime drug targets over the last two decades. Interfering intracellular PPIs with small molecules has been extremely difficult for larger or flat binding sites, as antibodies cannot cross the cell membrane to reach such target sites. In recent years, peptides smaller size and balance of conformational rigidity and flexibility have made them promising candidates for targeting challenging binding interfaces with satisfactory binding affinity and specificity. Deciphering and characterizing peptide–protein recognition mechanisms is thus central for the invention of peptide-based strategies to interfere with endogenous protein interactions, or improvement of the binding affinity and specificity of existing approaches. Importantly, a variety of computation-aided rational designs for peptide therapeutics have been developed, which aim to deliver comprehensive docking for peptide–protein interaction interfaces. Over 60 peptides have been approved and administrated globally in clinics. Despite this, advances in various docking models are only on the merge of making their contribution to peptide drug development. In this review, we provide (i) a holistic overview of peptide drug development and the fundamental technologies utilized to date, and (ii) an updated review on key developments of computational modeling of peptide–protein interactions (PepPIs) with an aim to assist experimental biologists exploit suitable docking methods to advance peptide interfering strategies against PPIs.
Delivering drugs specifically to patient neoplasms is a major and ongoing clinical challenge. Function-blocking monoclonal antibodies were first proposed as cancer therapies nearly four decades ago. The large size of these molecules hindered their commercial development so that the first antibody or antibody-fragment therapies were only commercialized for cancer therapeutics and diagnostics 20 years later [1,2]. A classic development during this period, a radiolabelled peptide analog of somatostatin (SST) was used to target neuroendocrine tumors expressing the SST receptor instead of targeting the receptor with an antibody [3]. The concept of using a peptide as a targeting moiety for cancer diagnosis and treatment has since led to current peptide drug developments in both academia and pharmaceutical industries. In addition to cancer treatments, melanotan 2 peptide that mimic natural peptide hormones also offer therapeutic opportunities. Synthetic human insulin, for instance, has been long exemplified for its clinical efficacy for diabetic patients [4].

In comparison to small molecules, such as proteins and antibodies, peptides indeed represent a unique class of pharmaceutical compounds attributed to their distinct biochemical and therapeutic characteristics. In addition to peptide-based natural hormone analogs, peptides have been developed as drug candidates to disrupt protein–protein interactions (PPIs) and target or inhibit intracellular molecules such as receptor tyrosine kinases [5,6]. These strategies have turned peptide therapeutics into a leading industry with nearly 20 new peptide-based clinical trials annually. In fact, there are currently more than 400 peptide drugs that are under global clinical developments with over 60 already approved for clinical use in the United States, Europe and Japan.

Protein–protein interactions (PPIs) are the foundation of essentially all cellular process. Those biochemical processes are often comprised of activated receptors that indirectly or directly regulate a series of enzymatic activities from ion transportation, transcription of nucleic acids and various post-translational modifications of translated proteins [7]. Drugs that bind specifically to such receptors can act as agonists or antagonists, with downstream consequences on cellular behavior. Peptides and small molecules that interfere with PPIs are thus in high demand as therapeutic agents in pharmaceutical industries due to their potential to modulate disease-associated protein interactions. Accumulating evidence has suggested that better identification of targetable disease-associated PPIs and optimization of peptide drug binding characteristics will be key factors for their clinical success [8].

Unfortunately, understanding the molecular recognition mechanism and delineating binding affinity for PPIs is a complex challenge for both computational biologists and protein biochemists. This is largely because small molecules are superior in binding to deep folding pockets of proteins instead of the larger, flat and hydrophobic binding interfaces that are commonly present at PPI complex interfaces [9]. Although monoclonal antibodies are more effective at recognizing those PPI interfaces, they cannot penetrate the cell membrane to reach and recognize intracellular targets. In recent years, peptides with balanced conformational flexibility and binding affinity that are up to five times larger than small molecule drugs have attracted enormous attention [10,11]. Cyclic peptides, for example have small molecule drug properties like long in vivo stability, while maintaining robust antibody-like binding affinity and minimal toxicity [12]. In this review, we will focus two aspects of peptide drug development: (i) Fundamental technologies utilized for peptide drug developments to date, and (ii) key developments of computational modeling techniques in peptide–protein interactions (PepPIs). Recent topics and basics in conventional docking of PPIs will also be covered with an aim to assist experimental biologists exploiting suitable docking methods to advance peptide interfering strategies against PPIs.

Retrograde ureteroscopy has recently gained a broadened indication for use from diagnostic to a variety of complex minimally invasive therapies. This review aims to look at the recent advances in the instrumentation and accessories, the widened indications of its use, surgical techniques and complications. With minimization of ureteroscopic instruments manufacturers are challenged to develop new, smaller and sturdier instruments that all will also survive the rigors of surgical therapy.

Ureteroscopy is defined as retrograde instrumentation performed with an endoscope passed through the lower urinary tract directly into the ureter and calyceal system.[1] With the addition of actively deflectable, flexible endoscopes the indications for ureteral access sheath have broadened from diagnostic to a variety of complex minimally invasive therapies. Current ureteroscopic treatments include intracorporeal lithotripsy (by far the most common), treatment of upper urinary tract urothelial malignancies, incising strictures, evaluation of ureteral trauma, and repairing ureteropelvic junction obstructions.[2,3] With improved instrumentation and incorporation of technologies such as a large endoscope working channel and active tip deflection, the evolution of surgical techniques have broadened while the complications noted with ureteropyeloscopy have actually decreased significantly.

The application of flexible fiber ureteroscope was first reported by Marshall in 1964. A 9F fiberscope manufactured by American Cystoscope Makers (Pelham Manor, NY) was passed into the ureter to visualize an impacted ureteral calculus. Subsequently, Bagley, Huffman, and Lyon began work at the University of Chicago to develop an improved flexible fiberoptic ureteropyeloscope in the 1980s.

The optical system consists of fiberoptic light bundles created from molten glass. Each glass fiber is cladded with a second layer of glass of different refractive index to improve the internal reflection, light transmission and also the durability of the endoscope. When the fibers are bundled randomly, they provide excellent light transmission for illumination, but no image. However, if the fibers are placed in a coherent fashion, the light from each fiber will coalesce to transmit images. Small lenses placed proximally and distally enable a telescopic effect with image magnification, increased field of view and focusing ability. A recent modification is the splitting of the light bundle distally to enable a more central placed working channel and better distribution of light within the working field of view.[5]

The deflection mechanism of the flexible ureteroscope permits maneuverability within the collecting system of the kidney. This deflection is usually provided by several wires running down the length of the endoscope and attached to a lever which is manually operated. Manipulating the lever will deflect the tip. If the tip moves in the same direction of the lever, the defection is described as “intuitive”- i.e. down is down and up is up. In the past, prior to 1992, deflection was active at the tip and secondary deflection along the shaft was passive. To obtain lower pole access, the urologist would maximally deflect and advance the tip of the endoscope.[6] The secondary deflection was achieved by the endoscope passively buckling at a set designed point along the shaft. In 1992, Karl Storz (KSEA, Tuttilegan, Germany) was able to downsize the flexible endoscope from 9.8 Fr to 7.5 Fr while maintaining the same 3.6 Fr working channel. This milestone event allowed all urologists to more easily pass the endoscope and in so doing broaden the therapeutic applications. The current instruments have continuous controlled dual deflection with increased downward and upward deflection up to 270 degrees, referred to as “exaggerated deflection” in both directions. This deflection is performed with a single more ergonomic lever as compared to the cumbersome two separate levers employed by the ACMI DUR 8 (Gyrus Inc, London, England). The radius of deflection is also broader, thereby enabling more maneuverability and permitting placement of instruments in the lower pole. The most modern endoscopes also incorporate a shock absorbing system (a form of secondary deflection) which is located proximal to the active deflecting system and allows for gentle rolling of the distal end for approximately ten centimeters enabling access more deeply into the calyces.[7]

The working channel permits placement under direct vision of a variety of accessories including graspers, baskets, wires and laser fibers through the endoscope. All current endoscopes have a channel of at least 3.6 Fr which allows the use of instruments up to 3 Fr while still permitting concurrent irrigation. The composition material of the accessory influences tip deflection. For example, graspers and baskets with a shaft composed of polyamide tend to be stiffer and inhibit deflection as compared to Teflon sheathed accessories.[8]

Many ureteroscope repairs are due to damage to the working channel from malfunction or incorrect use of the holmium laser. This is often a technical issue when the fiber firing end is located too close to the endoscope tip. The new-generation Storz endoscopes incorporate a bead-like sequence of hollow ceramic rings in the distal end of the working channel for 1.5 cm. This protects the instrument from thermal or electrocautery damage and allows the endourologist to work closer to the tumor, stricture or stone while using laser energy.

White and Moran reported the need for major urteroscope repairs after only 12 endoscope usages.[9] Afane et al., demonstrated that flexible ureteroscopes from four major manufacturers required major repairs after only 15 procedures or 13 h of usage.[10] Traxer et al., from Paris performed 50 flexible ureterosopies using the Karl Storz Flex-X ureteroscope. They evaluated the maximal active ventral and dorsal deflection, irrigation flow at 100 cm H20 and number of broken optical fibers. The maximal ventral deflection deteriorated from 270 degrees initially to 208 following the last procedure; the maximal dorsal deflection decreased from 270 to 133 degrees. The irrigation flow at 100 cm H20 decreased from 50 to 40 after the last procedure. They concluded that the need for repair occurred less frequently with the newer generation endoscopes and when used by an experienced endourologist.[11] In general most centers can employ these instruments for approximately 50 cases between repairs with damage and breakage occurring most often during sterilization.

Irrigating fluids are employed to clear the optical field of view and to cool the tip of energy-delivering devices. The irrigant is delivered through the same channel used for working instruments, often through a side arm adapter (Urolock – Boston Scientific, Natick Mass. and Check flow, Cook Urologic, Spencer, Indiana). The simplest and most cost-effective means of delivering continuous irrigant is to employ two 60 cc syringes connected to a three-way stopcock with arterial line tubing. Normal saline is the irrigation standard solution for diagnostic ureteral stent and lithotripsy. When electrocautery is employed sorbitol or small aliquots of sterile water may be used.[12]

Accessories include guide wires, stone retrieval devices, access sheaths, electrodes, laser fibers, biopsy forceps, etc. With regard to guide wires, the PTFE -coated stainless steel guide wire and the Zebra wire (PTFE coated with nitinol core – Boston Scientific, Natick Mass) are useful to help facilitate endoscope tip access to the ureter in routine cases. The Terumo Glide wire is particularly useful in cases of difficult ureteral access. It is employed as an access guide wire and not a working guide wire. This means that the very lubricious coating is useful in bypassing an obstruction, and can facilitate ureteral catheter placement, while the slippery nature of this nitinol design frequently does not aid in placing the larger endoscope.

Several new unique guide wires are now available including the Sensor wire (Boston Scientific, Natick, Mass.). The Sensor guide wire, for example, has a smooth hydrophilic nitinol-based distal tip, a kink-resistant body made of nitinol alloy core, and PTFE-coated stainless steel jacket which adds stiffness and helps prevent endoscope buckling during endoscope placement into the ureter. This guide wire also has a flexible proximal tip for atraumatically back loading the wire through the working channel of the ureteroscope.[13,14]

The ureteral access sheaths can facilitate repeat ureteroscopic access to ureter. These sheaths range from 12-14 Fr and enable repeated passage of the ureteroscope without a guide wire. The advantages include easy endoscope placement and possible decreased intrarenal irrigant pressures. The disadvantages include over-dilation for placement, false sense of security, and potentially increased rate of ureteral stricture from prolonged use.[15]

Recently, flexible digital ureteroscopes have been introduced. These endoscopes have an integrated light source and distal digital chip-based camera. The distal chip camera system requires a larger outer endoscope diameter which is an issue for access, while the image quality is equivalent to ten times the pixel resolution of standard fiber optic endoscopes. Since these instruments do not require a separate camera head or light cord, they may potentially be more durable.

More studies are needed before concluding that these more costly additions are superior to the conventional fiber optic flexible endoscopes. Early issues include digital processing of colored light, especially red light, and problems with chip stability during laser lithotripsy where the created acoustic percussions distort the digital images.

The intramural ureter is the narrowest segment and can prohibit endoscope passage. Guide wires often are passed into the ureteral orifice cystoscopically and then directed into the renal pelvis with fluoroscopic assistance. These “safety” guide wires straighten the ureter and facilitate both the dilation of obstructed segments with balloon or graduated dilators and the placement of internal stents.[17]

Historically, the intramural ureter required dilation for endoscope access. Currently, the small-diameter flexible ureteroscopes often have less than 7.5 F tip diameter, and can be passed without any formal dilation. Use of a dilator to facilitate passage of the ureteroscope beyond the intramural tunnel is recommended when the ureter is narrow or restrictive. This is common in the young male population. Otherwise, the use of such dilators or operative sheaths is optional and generally not required.[18]

One access method is to employ a 10 Fr dual lumen catheter first over the initial access guide wire. This aids in both dilating the intramural ureter and in facilitating passage of a second “working” guide wire. This scheme is useful when the ureter is tortuous or J-hooked distally. The orifice can also be dilated with a balloon dilator (most commonly 12 F for access) and a second working wire passed beside. The flexible ureteroscope is next passed over the working guide wire in a monorail fashion into the ureter and the working guide is removed. Alternatively, the smallest diameter ureteroscopes (7.5 F tipped) can be passed directly into the ureter under direct vision without guide wire assistance. Fluid irrigation facilitates flexible ureteroscope optical visibility. Although automatic pumps are available for this purpose, hand irrigation is often preferred.[19]

In a recent prospective study of 460 consecutive upper-tract endoscopies at our center, “no-touch” direct access ureteroscopy (i.e. placement of the endoscope into the ureter under direct vision without the assistance of a guide wire and without dilation) was successfully performed in the majority of patients. This wireless form of flexible digital ureteroscope system or “no touch technique” is technically challenging but eliminates the potential trauma, mucosal irritation and inadvertent manipulation of stones or tumors caused by guide wires and is particularly helpful when mapping the collecting system for mucosal lesions or upper tract transitional cell cancers.[20]

Another access technique is to pass the tip of a guide wire through the endoscope just beyond any blockage, or kink in the ureter and then follow with the ureteroscope until it rests beyond the obstruction. This will open or straighten ureteral segments, often allowing easier passage.

Lower-pole intrarenal access performed with a flexible ureteroscope is often challenging and commonly requires both active and passive flexible ureteroscope deflections. To place the tip of the endoscope into the lower pole, the instrument must first be actively deflected and then advanced so as to allow the shaft below to buckle. This maneuver, termed secondary deflection, is required in 60% of traditional flexible ureteroscopies if a complete inspection is to be attained. The increased active tip deflection offered by new-generation flexible ureteroscopes significantly decreases the need for secondary deflection and enhances the surgeon's ability to inspect all aspects of the renal collecting system. Fluoroscopic guidance is frequently employed to provide a road map of the intrarenal collecting system. The flexible ureteroscope is directed from calyx to calyx, and frequently dilute contrast material is injected through the working channel of the endoscope to help ensure the entire collecting system is mapped.[21,22]

If electrocautery is to be employed, special attention to the guide wire choice helps prevent intraoperative complications. If a standard stainless steel guide wire is used, electrical current may inadvertently arc to the wire during cautery use and cause excessive ureteral coagulation with subsequent fibrosis and stricture formation. This can be prevented by using an insulated guide wire such as a Teflon-sheathed nitinol Zebra wire (Boston Scientific, Natick, Mass.).

Most ureteroscopic lithotripsies are performed as day surgery outpatient procedures. Patients are discharged on prophylactic oral antibiotics and analgesics. Anticholinergic medications and alpha-blockers may be used to minimize symptoms of frequency, urgency, and discomfort often associated with ureteral stents; however, individual patient tolerance varies. Choosing the correct stent length (based on the ureteral length) and optimal positioning help to minimize unpleasant symptoms.

In general, the minor complication rate from ureteropyeloscopy has decreased based on refined technique, experience of the operators, and prompt treatment or prevention of intraoperative problems. Prophylactic parenteral antibiotics, careful guide wire placement, minimization of excessive ureteral dilation, and postoperative ureteral stenting all impacted on the rate of postoperative problems. This, combined with better surgical training and improved instrumentation, resulted in this very positive trend.

Major intraoperative complications
The major complication rate associated with therapeutic visual ureteroscope series has decreased markedly and currently occurs in less than 1% of all procedures. As with the minor problems, major complications occur less frequently for basically the same reasons – better surgeon skills and improved instrumentation. However, when they do occur treatment is often more complex. In addition to major intraoperative problems, other complications that occur during upper urinary tract endoscopy may begin as minor events and, if left untreated or if addressed incorrectly, can progress to more serious conditions.

Major ureteral wall perforations occur infrequently and can be the product of a heavy-handed endoscopist and improper application of the ureteroscope. These complications are more common with the semi-rigid ureteroscopes rather than the flexible ureteroscopes. The forceful positioning of a semi-rigid ureteroscope above the iliac vessels, particularly in young male patients, is associated with a significant risk of ureteral wall trauma unless the collecting system is dilated or the ureter has been stented prior to endoscopy. Routine use of a double-J stent is not necessary in most patients but is recommended when unusual difficulty is encountered or when extensive strictures are noted. It is essential to note that if the endoscopic maneuvers are difficult, the surgeon can only be rewarded with an easier time in the future if he does not push the procedure but rather places a stent and returns another day. Usually, one to two weeks of stenting greatly facilitates ureteroscopy, particularly if proximal access is desired.

Care must be taken when treating stones in the ureter. Ureteral wall perforation with stone migration into the defect can lead to formation of a stone granuloma and/or ureteral wall stricture. In addition, attempts at extracting a particularly large stone with a basket rather than fragmenting it can lead to a ureteral perforation or avulsion. The general rule is if a stone or fragment is too large to pass on its own, trying to extract it with an accessory without reducing its size with an endoscope lithotrite has inherent risk.[25]

When distal ureteral avulsion is noted, ureteroneocystostomy repair can be performed, with a psoas bladder hitch if necessary to create a tension-free anastomosis. A Boari bladder wall flap will increase the proximal extent of the repair to the middle third of the ureter. These repairs are performed most commonly over a ureteral catheter with perianastomotic drainage. This can be performed acutely at the time of the injury or in a staged fashion after proximal percutaneous drainage is obtained at the time of the injury.

If the entire devitalized ureteral segment is inadvertently brought into the bladder, it is of no value in subsequent repair. Percutaneous renal drainage should be obtained immediately at the time of this type of ureteral injury. Subsequent therapy is based on either bowel interposition (i.e., ileal ureter) or renal auto transplantation to a pelvic position. Both procedures are complex and should be performed in a staged fashion after a period of healing Table 2.