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.
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]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]
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.

SVG Principle
The principle of the SVG static var generator is very similar to that of Active Power Filter, as demonstrated in the picture below. When the load is generating inductive or capacitive current, it makes load current lagging or leading the voltage. SVG detects the phase angle difference and generates leading or lagging current into the grid, making the phase angle of current almost the same as that of voltage on the transformer side, which means fundamental power factor is unit.
Delta’s PQC series SVG is also capable of correcting load imbalance.
SVG Structure
Delta PQC Series SVG static var generator is also modular in design, and the Delta SVG system consists of one or several SVG modules and an optional Liquid Crystal Monitor & Control Panel (LCM). Each SVG module is an independent reactive power compensation system, and users can change the SVG rating by adding or removing SVG modules.
SVG modules and LCM panel can be embedded in Delta’s standard SVG cabinet or in a customized cabinet. There are usually breakers, cable terminals and Surge Protection Device (SPD) in the SVG cabinet.
Active harmonic filters are more of a system solution. How do they work?
Harmonics come from the nonlinear load. Active harmonic filter, also called harmonic correction units, is parallel devices that act like a noise cancellation system and inject equal and opposite frequencies to mitigate harmonics. The filters can also provide additional current to correct the power factor. So, what’s left coming from the source flowing back to the utility is only a nice, clean current that is in phase.
For example, if we run four 6-pulse variable frequency drives at the same time, we have a harmonic spectrum of 5th and 7th and 11th and 13th harmonics. The waveform will show a significant amount of harmonic current in the total harmonic distortion. When the active harmonic filter is turned on, it will inject equal and opposite harmonics to cancel what’s there. The waveform now will be clean and in phase. If we go back and look at the harmonic spectrum, the current distortion is very low.
Adding active harmonic filters can be a good harmonic solution for power systems. Though more costly than other options, if you have multiple drives running all the time and multiple drives as backup, harmonic filters would be a reliable way to capture any and all of the harmonics coming from the loads. However, one important thing to know from a system design standpoint is that your drive should have either a DC choke or an AC line reactor to minimize the harmonics coming out of the drives.
Active harmonic filters typically come in 50, 60, 100, 200 and 300 ampere units that you can parallel. Another benefit to using active harmonic filters is that you cannot overload them, because once they put out the maximum harmonic current and power factor correction that they can, they stop producing at that level—whether it’s 100 or 120 amperes, whatever the case may be.
Using active harmonic filters on your power system provides a system-level solution for internal and external harmonic protection.
What are active harmonic filters?
Active harmonic filters are parallel filters (which means the current doesn’t go through the filter) that are used to reduce, or mitigate, harmonics to tolerable levels as defined by IEEE-519. Active filters use a set of transistors and capacitors to filter (or clean) the current wave by injecting inverse currents to cancel out the undesired harmonic components. Active filters are significantly more expensive than passive filters and take up more space. Size is an immense factor in system design today and should be accounted for when deciding on what type of harmonic filter is right for you.
Active filters can work with multiple drives; when the active filter reaches its limit, it won’t overload. In addition, if an active filter breaks, it won’t stop the motor (since current isn’t going through the filter); it just won’t filter the current wave.
Active harmonic filters can effectively cancel harmonic distortions from the network. This blog post will explain the key criteria that should be kept in mind when buying an active harmonic filter.
1.1. Inverter topology
Most modern AHFs are built on 3-level NPC inverter topology which brings several benefits compared to AHFs built on the conventional 2-level topology. In 3-level topology, the switching frequency and voltage stress are distributed among the IGBTs. Reduced stress extends the lifetime of the power electronics. Higher efficiency, lower losses and lower noise levels are also achieved. These make the overall cost of ownership much lower.
1.2. Losses
Depending on design and topology, AHFs can have higher or lower losses. Checking the losses is important as they will reduce the life cycle cost of the investment. Usually AHFs have about 2-3% losses (depending on rated power). AHFs built on 3-level NPC inverter topology have lower losses than 2-level ones. Depending on the user profile, reduced losses create a potential for considerable financial savings if the LCC is calculated over a period of few years.
1.3. Response time
Some power quality phenomena occur extremely fast, requiring the mitigation to be even faster. If the process is affected by fast voltage fluctuations or transients, it is very important to evaluate the AHF’s overall response time.
1.4. Interharmonics
Interharmonics are usually caused by synchronization issues. If the installation includes interharmonic sources, the manufacturer should be consulted as not all AHFs can deal with this. It is a common issue with cycloconverters or some types of older wind turbine generators.
1.5. Harmonic compensation capacity
Harmonics can be seen in the odd and even orders. Common capacity for AHFs is 25th or 50th harmonic order. Sometimes there is a claim of being able to mitigate the 51st harmonic, which has little value as harmonic orders of 51st and above do not appear in electric power systems. An important issue is that the AHF can offer the possibility of selecting which harmonic order to compensate. For some devices, it is possible to select the whole harmonic spectrum (1st to 50th, odd and even), but for some others only few harmonic orders can be selected. Depending on the application, the capacity to compensate a certain harmonic order is a critical issue affecting the performance of the whole system.
1.6. Electromagnetic compatibility (EMC)
In some countries there are strict guidelines regarding the EMC. To be sure that the AHF is not causing interference it must be fitted with a properly designed EMC filter.
1.7. Derating according to harmonic order
The rating of an AHF is usually defined at nominal load (at 50/60Hz). As the AHF works further up the harmonics, its capacity compared to nominal starts to derate. For example, a derating of 50% at the 13th harmonic order means that a 100A AHF has only the capability to compensate 50A at the 13th harmonic order.
Derating is a matter of how robustly the AHF is designed. This capability is more dependent on the change rate of the current than just the frequency and magnitude of the current (all different frequencies, their magnitude and phase have an effect). Because of this, a derating curve cannot show the capability of the AHF. The only way to verify the real compensating capability of a device is to check its di/dt capacity. This compensating capability is clearly better in 3-level NPC inverter topology AHFs compared to 2-level topology devices.
1.8. Physical footprint and modularity
Most suppliers offer several installation alternatives: Cubicle type, wall mount or loose modules that can be locally installed inside new or existing cubicles. A modular AHF design allows customers to adapt to potential changes in future harmonic filtering and reactive power compensation needs. Modular design means that it is possible to add easily to the AHF’s capacity within the existing configuration, saving both costs and space.
1.9. Voltage
AHFs are offered in a range of voltages, most common is 200V up to 690V. Some manufacturers can produce AHFs for higher voltages, up to 1000V, without step-up transformer, reducing costs and footprint. It is possible to connect AHFs to high voltage (over 1kV) systems using a suitable step-up transformer. Step-up (or step-down) transformers can reduce compensation performance due to increased impedance between the AHF and network.
1.10. HMI
There are different HMI setups for AHFs. Some have a very simple front HMI while others include graphs showing the current and voltage waveforms and many further functions in different languages. A great added value is to have at least a web-based interface allowing in-depth monitoring and control functionality.
1.11. Commissioning software
Commissioning and service of AHFs without proper tools can be time consuming. Some suppliers provide software for this. Minimum required functionality should be that the system performs a self-check of voltage and CT phase order, CT polarity check, self-diagnosis and self-calibration. Such features will find installation errors before they can cause problems and will shorten the commissioning time. If the AHF does not have this type of software the commissioning becomes more complex and might require external support adding to the system costs.
1.12. Smart Grid functionality
Some AHFs have a built-in power quality analyser to calculate the required compensation. Some suppliers enable the user to connect all AHFs on site through a web-based architecture. An operator can then have an overview of the status of all connected AHFs and log them. This enables the possibility to log events that could have caused production disturbances, monitor individual AHFs, and remote monitoring and analysis capability.
1.13. Control of detuned capacitor banks
Very often AHFs are installed at sites together with existing or new contactor or thyristor switched detuned capacitor banks. Some suppliers offer the possibility to control the steps of these banks directly from the AHF’s control system through dedicated digital outputs in the AHF. By doing this it is possible to use the comprehensive power quality monitoring and reporting features of AHFs to accurately monitor all the parameters of the installation and control the total power quality improvement needs. This brings an optimal system integration, efficient operation, cost savings on the control system, and the possibility to build hybrid var compensators (HVC).
1.14. Cancellation of harmonics in neutral (4W)
Typically, active harmonic filters are installed to cancel harmonics distortions created by AC and DC drives or UPS systems. However, use of LED lighting as well as other single-phase loads in the buildings also produces tripplen harmonics which accumulate in the neutral wire and should also be mitigated. Therefore, active harmonic filter should be easily configurable to 3W or 4W applications.

The inception of the dust collector has allowed companies to effectively capture airborne particulate from an air stream. This has become more important for several reasons. First, containing particulate — toxic or not — is necessary to provide a healthy and clean work environment. Second, increasing local and global awareness of air pollution, containment and the process dust in industrial applications has emphasized the importance of dust collectors. Finally, expanding regulations have pressured companies to properly design, install, operate and maintain dust collection equipment.
To ensure dust collector bags are functioning properly, you need to perform periodic inspections, as well as repair and replace damaged or malfunctioning equipment. A routine inspection and maintenance program will boost your equipment's performance and life. To maintain the health and effectiveness of your dust collector, follow our helpful list of procedures.
1. Create an inspection/maintenance program — A typical program consists of a schedule for periodic inspections that are performed on a daily, weekly, monthly, semi-annual and annual basis. Failing to periodically inspect the dust collector can hurt its performance. Subsequently, the dust collector may not meet EPA outlet emissions standards.
2. Don't exceed recommended pressure drop — Sometimes called differential pressure, it's the amount of static resistance across filters when operating a positive- or negative-pressure dust collector. Pressure drop, typically measured in inches of water column (in w.c.), is a good indicator of the amount of dust that has collected on the filter media and, if continually monitored, the condition of the filters.
New filters have the lowest pressure drop because of the inherent permeability of the media. As the bags develop a dust cake, some particulate embeds itself into the filter media, increasing pressure drop accordingly. The filtering of the airstream through this accumulated dust cake provides high-efficiency collection of fine particulate. In fact, the highest efficiency a dust collector can offer is just before the cleaning is initiated. However, high differential pressures can cause filter media bleed-through or blinding. Therefore, do not to exceed the manufacturer's recommended operating pressure drop.
3. Ensure cleaning system functions properly — Equipment use a variety of cleaning systems to dislodge accumulated dust cake from the filter media. Systems include reverse air, shaker or pulse clean. Regardless of the style of cleaning, it is imperative that this system function properly at all times. Without an effective cleaning system, dust will continue to build on the bags. The result will be an increased pressure drop and reduced volume of ventilation air at the pick-up points. Further, airstream velocities within the ductwork will decrease and cause dropout of dust in the ducts. This may choke the entire system and render it ineffective.
4. Watch for visible emissions — This includes any particulate that can be seen discharging from the exhaust stack. These emissions indicate a breach in a seal or a broken (torn) filter. In either case, you must find and correct the leak immediately. Not only will the emission cause a health concern and damage the property outside the plant, but it may also bring about monetary fines imposed by local, state and federal environmental agencies. Additionally, fans located downstream of the collector can be damaged from abrasion or become imbalanced if you don't correct this condition quickly.
Continually monitor exhaust from the dust collector. Besides visual inspections, consider incorporating a broken bag detector into the clean air ductwork. If a bag begins to fail, or there's a leak in the bag seal, you'll detect the particles that bypass the media. Typically, these detectors use triboelectric technology. These devices can be wired to an alarm horn, siren or PLC.
5. Select the right exhaust fan — Dust collection systems require an exhaust fan to accelerate ventilation air from the point of pick-up, through the ductwork and dust collector filter media and out the exhaust stack. Fans are selected to accommodate volume (SCFM) and pressure drop throughout the system. Calculate the pressure drop by evaluating the static resistance of the dust collector, ductwork and pick-up points/hoods.
6. Inspect the filter media — This is the most important item in a dust collector because it accumulates and supports a dust cake. This dust cake is what provides high filtering efficiencies during operation. Inspect the clean-air side of the dust collector for leaks and the bags for tears. If pressure-drop within a dust collector becomes extremely high relative to historical data, it may be caused by excessive dust cake or blinding of the filter bags.
Depending on the application, differential pressure may take a number of hours or even days to develop. It is essential that you keep filtering velocities low for new filter media. Reducing the volume decreases the airstream's velocity, thus protecting the bags from high-velocity impingement of dust. If you expose bags to the fan's full volume, fine particles may embed themselves into the bags' inner fibers and begin blinding. This can also reduce the life of the bags by damaging the fibers of the media. So make sure to season a collector's filter bags.
This is not an all-inclusive list. Each piece of equipment and application is different, and each has its own unique components and features. But these simple procedures can help you monitor and maintain your dust collector's heath, as well as prevent shutdowns due to inefficiencies, prolong filter life and prevent costly EPA fines.
Dust Filter Bag
The welding of the filter bag cage is not standardized. The unevenness of the welding frame of the filter bag cage or friction with the cabinet will cause the dust filter bag to be worn out during shaking. Generally, the uneven surface of the filter bag cage refers to burrs or edges at the welding place;
The dust bag installation is not standard. The dust filter bags are too loose when suspended, which may cause the dust filter bag to collide or friction with other components, resulting in damage to itself;
The disassembly and assembly of the dust filter bag is not standard. When the dust filter bag is disassembled or installed, it is likely to collide with metal edges and wear the cloth bag. This kind of injury is not easy to detect, but ash will appear during work;
The cleaning cycle is unreasonable. The dust removal cycle is too short and the dust removal method is wrong, which will increase the burden on the dust filter bag and cause the dust filter bag to be easily damaged;
Dust-containing gas properties. The temperature of the dusty gas is too high, the concentration is too high, and the wind speed is too high, etc., it will increase the burden of the dust filter bag and easily cause premature damage to the dust filter bag. In addition, if the dust filter bag used fails to match this working condition, it is easy to burn. On the contrary, if the temperature is too low and the wind speed is low, it is easy to cause condensation and dust removal of the dust filter bag. The high dust filter bag needs to be replaced.
Five Things You Should Know about Dust Collection Filter Media
#1: Most industrial dust collection manufacturers design filters or collectors. Few design both.
The customer wins when a manufacturer understands the behavior of both the filter media and the dust collector and designs both. When a supplier can optimize the interaction between the filter media’s performance and the collector’s performance as a single consolidated system, the customer benefits by a more stable and dependable operation and lower operating costs.
#2: Effective filter media designs may require thousands of computer simulations before initial lab samples are produced or final media grades are released to production.
Filter media development is very involved and includes the testing of raw materials and properties of filter media blends. Raw material testing and media development labs often evaluate media components using: high-performance liquid chromatography (HPLC), FTIR (Fourier Transform Infrared) Spectroscopy, TD-GC-MS (Thermogravimetric Analyzer - Gas Chromatography - Mass Spectrometry), and SEM (Scanning Electron Microscopy). These tools help ensure the optimal design and materials are being used to appropriately match the application conditions.
Development of Donaldson media grades includes computer modeling to predict tensile strength, stiffness, permeability, and a variety of other filtration and efficiency levels. This modeling helps ensure a thorough understanding of the potential physical properties of a media recipe before a test recipe is even produced in the lab. When a recipe shows promise, samples are produced in the lab so physical testing can confirm the predicted properties.
Donaldson considers filter media development one of its core competencies. Even so, with all our background and experience, new media recipes still go through thousands of computer and lab iterations to achieve the optimized characteristics before we begin production of a new media grade.
#3: There’s more to manufacturing filter media than meets the eye.
The general process of developing any filter media should begin by identifying the application requirements. Then specifications are determined for not only the finished media grade, but for the final filtration product in which the dust filter media grade will be incorporated (i.e. cartridge, panel, or filter pack).
Factors to be considered in media recipe formulation include: a cost level which makes sense for the market; minimum efficiency levels needed to achieve acceptable emissions; the type and amount of material being filtered from the fluid stream by the media filter; and the physical environment to which the media will be exposed. Other factors include: pressure, vibration, temperature, humidity, and chemical composition of contaminants.
Pressure drop, or the resistance necessary to cause fluid flow through the media, is considered critical to media design because this impacts the energy it takes to move fluid through the media and, therefore, the operating cost of the filter developed.
All of these variables are considered important, and they must be balanced against one another to formulate an optimized media grade for an application. For example, a formulation may use expensive materials and provide high efficiency, yet the very dense filter media might be expensive to operate in the collector because of the high pressure drop of the filter and its replacement costs. A dense filter media design might also compromise the performance of a cleaning system and could result in shorter overall filter life and increased maintenance material and labor costs.
On the other end of the spectrum, a filter media comprised of low cost materials with low pressure resistance may offer initial benefits. However, if the media does not handle the physical challenges of the operation or becomes quickly plugged, the operational disruption and maintenance downtime and expense make it a poor choice. Optimizing the various performance measures is essential to overall collector performance.
#4: Some manufacturers offer 300+ grades of filter media from which to choose.
Some manufacturers are so serious about providing exactly what the customer needs they offer hundreds of choices to the market, each tailored to meet specific challenges and requirements. If an appropriate media does not exist for an application, new media development may be undertaken.
#5: Evaluating dust collection manufacturers pays off.
When evaluating dust collection manufacturers, look for one that offers media grades optimized for your application and for the collector in which they will operate. This will help optimize your filter efficiency performance, extend your filter life, and lower your cost of ownership. Choose a company with a strong history of providing expertise and technical support.
If you’re employed by a global company, consider a global dust collection manufacturer that can provide excellent customer support around the world – including stock inventory of common filters and parts so they are ready to ship when you need them. A company like this will provide you exactly what you need.

As the name indicated a temperature compensated crystal oscillator provides a means of counteracting the frequency change caused by temperature change in a crystal oscillator.
The letters TCXO stand for Temperature Compensated Xtal Oscillator - Xtal is short from crystal and implies a quartz crystal resonator. The TCXO module is able to provide considerably improved performance over that of a standard crystal oscillator, especially in terms of frequency stability over a temperature range.
By measuring the temperature and applying a correction voltage to a VCXO, the frequency stability over a temperature range is considerably improved whilst keeping costs low - using an oven controlled crystal oscillator, OCXO would be considerably more costly and much larger in size.
Often a wide range of TCXOs of varying frequencies, supply voltages and packages is available from many distributors, enabling these electronic components or modules to be used in many general electronic designs, RF circuit designs, etc.
Temperature performance of crystal oscillator
Crystal oscillators are able to provide a much better level of performance than that provided by LC resonator circuits. Nevertheless crystal oscillators are still affected by temperature.
The angle of the cut and other aspects of the quartz crystal have a major impact on the performance.
As a result special cuts are defined and one known as the AT cut is the most widely used for these and many other quartz crystal RF applications. This gives a good level of performance for RF circuits in terms of suppression of unwanted modes of vibration as well as the frequency range available, and also the temperature stability.
Despite this, AT cut crystals on their own cannot meet the requirements for many applications and temperature compensation is required if they are to perform satisfactorily over the required range - often 1 - 70°C at elast is needed.
The effects of temperature are, to a large degree, repeatable and definable. Therefore it is possible to have an electronic design to compensate for this. By adding additional electronic components to the basic oscillator, it is possible to considerably reduce the effects caused by temperature changes: a temperature compensated crystal oscillator, TCXO.

TCXO solution
A TCXO adjusts the frequency of the oscillator to compensate for the changes that will occur as a result of temperature changes. To achieve this, the main element within a TCXO is a Voltage Controlled Crystal Oscillator, VCXO. This is connected to a circuit that senses the temperature and applies a small correction voltage to the oscillator as shown below.
INTRODUCTION
The history of the development in crystal filter technology, from the initial concepts of Cady to the current wide range of products, provides a fascinating chapter in the development of today’s highly complex electronic products. The crystal filter has been a particularly critical element in the development of narrowband communications systems. The desire to send multiple voice messages on a single telephone line resulted in the introduction of carrier telephone systems in 1916. These early systems used LC filters in the 10 to 40 kHz frequency range. However, the bandwidth limitations caused by realizable coil Q’s were quickly recognized. In 1929, W.P. Mason of Bell Laboratories developed methods for incorporating crystals into LC lattice filter networks. This work resulted in the development of a 60 to 108 kHz basic group-band filter set used to frequency multiplex 12 voice channels. This work is described in Mason’s 1934 paper which was the basis for essentially all crystal filter designs generated during the next 20 years. During this period the major application for crystal filters was in carrier telephone equipment. However, in the mid-1950s, newer narrowband radio communications systems were developed both for military and commercial use which required high-frequency, stable, narrow-bandwidth filters. In most cases, crystal filters were the answer for these filtering applications and a new manufacturing industry was formed to supply these needs. Other applications quickly followed in navigation and radar equipment, in new fire-control systems, and missile control systems. This increased level of activity resulted in new filter design procedures and substantial improvement in the quality of high-frequency filter crystals.
In the 1960s another major technology step occurred with the development of monolithic crystal filters. Through the 1970s and ’80s evolutionary improvements were made with the development of multi-pole monolithic filters and the extension of the high frequency limits through continued process improvements. Significant theoretical work was also accomplished in this period in the area of device modeling. High frequency limits are still being pushed today with blank etching techniques and improved photo-lithography.
DESIGN EVOLUTION
Professor Walter Cady, who carried out much of the original development work on quartz crystals, was apparently the first to suggest the use of crystals as filter elements. In his 1922 paper he shows single-mode crystals with divided electrodes which could be used as coupling elements between adjacent circuits. However, in this configuration, only very narrow bandwidths are achievable and the filter would be useful only as a carrier-frequency filter. In 1927 patent disclosures were filed by L. Espenschied of AT&T and C. Hansell of RCA on the use of crystals in a filter structure. The Espenschied patent shows the use of crystals in a ladder filter structure in a variety of configurations. He also shows the use of inductors in series or in shunt with the crystals to widen the filter bandwidth. In Hansell’s patent the use of a bridge circuit is shown using all capacitors or a center-tapped transformer to balance out the crystal shunt capacitance. This is essentially the hybrid-lattice configuration which is commonly used in discrete crystal filters. He also proposed a method for widening the bandwidth by placing several crystals with slightly different frequencies in parallel. The challenge of providing filters with useful bandwidths was apparent from the earliest days and many techniques (usually unsuccessful, including Hansell’s) were attempted. In his patent Hansell makes the interesting observation that “The crystal filter has the advantage of being so sharply selective that the necessity for more than a single section probably will never arise.”

Ceramic Filtration
Locally manufactured ceramic filters have traditionally been used throughout the world to treat household water. Currently, the most widely implemented ceramic filter is the Potters for Peace design. The filter is flowerpot shaped, holds about 8-10 liters of water, and sits inside a plastic or ceramic receptacle. To use the ceramic filters, families fill the top receptacle or the ceramic filter itself with water, which flows through the ceramic filter or filters into a storage receptacle. The treated water is then accessed via a spigot embedded within the water storage receptacle. The filters are produced locally at ceramics facilities, and then impregnated with colloidal silver to ensure complete removal of bacteria in treated water and to prevent growth of bacteria within the filter itself. Numerous other locally-made and commercial ceramic filters are widely available in developed and developing countries. The filter is flowerpot shaped, holds about 8-10 liters of water, and sits inside a plastic or ceramic receptacle. To use the ceramic filters, families fill the top receptacle or the ceramic filter itself with water, which flows through the ceramic filter or filters into a storage receptacle. The treated water is then accessed via a spigot embedded within the water storage receptacle. The filters are produced locally at ceramics facilities, and then impregnated with colloidal silver to ensure complete removal of bacteria in treated water and to prevent growth of bacteria within the filter itself. Numerous other locally-made and commercial ceramic filters are widely available in developed and developing countries.
Lab Effectiveness, Field Effectiveness, and Health Impact
The effectiveness of ceramic filters at removing bacteria, viruses, and protozoa depends on the production quality of the ceramic filter. Most ceramic filters are effective at removing bacteria and the larger protozoans, but not at removing the viruses. Studies have shown adequate removal of bacterial pathogens in water filtered through high quality locally-produced or imported ceramic filters in developing countries. A 60-70% reduction in diarrheal disease incidence has been documented in users of these filters. Studies have also shown significant bacterial contamination when poor-quality locally produced filters are used, or when the receptacle is contaminated at the household level. Because there is no chlorine residual protection, it is important that users be trained to properly care for and maintain the ceramic filter and receptacle.
What Is a Ceramic Resonator?
A ceramic resonator is an electric component that exhibits a series resonant and a parallel resonant center frequency. It exhibits a piezoelectric characteristic that makes the ceramic material generate minute electrical energy when subjected to electromechanical expansion and compression. The resulting mechanical energy component produces the electric component and vice versa, and the result is a complex reactance that leads to resonance observed as the characteristic of having a center frequency. Materials such as lead zirconium titanate have a ceramic piezoelectric characteristic.
Oscillators are electronic circuits that generate periodic waveforms. The ceramic resonator may be used as a frequency reference in the electronic oscillator, wherein the accuracy of the resulting frequency is not as high as in the crystal oscillator. Error in frequency for the ceramic resonator circuit may be as high as 5%, while that for the crystal oscillator is less than 0.1%.
The ceramic resonator may also be used for intermediate frequency (IF) amplifier stages, which are found in heterodyne radio receivers that derive a common IF to receive a sub-band of frequencies. For instance, a radio receiver tuned to 1,000 kilohertz (kHz) or 1,000 cycles per second may generate a local oscillator frequency of 1,455 kHz so that the difference is 455 kHz, which is a typical IF frequency. To receive a 1,500 kHz signal, the local oscillator is tuned to 1,955 kHz and the resulting difference is still 455 kHz. This ceramic resonator is tuned or cut to resonate at around 455 kHz and will serve a sub-band like 550 to 1,600 kHz as in a typical amplitude modulation (AM) band.
A typical ceramic resonator has three terminals. The two main terminals are at each wide side of a thin ceramic material, while the middle terminal is usually connected to the thin side and may be grounded or used to tap signal into the rest of the oscillator circuit. There are, however, ceramic resonators as well as crystal resonators with only two terminals.
Amplifiers are the active parts of the oscillator. The ratio of the output voltage to the input voltage of an amplifier is known as the voltage gain, which is dependent on the frequency of interest. Very few amplifiers will maintain a constant gain over a wide range of frequency. When a ceramic resonator controls the oscillator frequency, the voltage gain at the ceramic resonator frequency has to be greater than 1. If the voltage gain is less than 1, the amplifier will not start oscillating.
In electronics, design amplifiers and oscillators have very common components. With design shortcomings, some amplifiers can be very close to oscillating. Meanwhile, some oscillators may just stop oscillating and behave like idle amplifiers. Ideally, amplifiers do not have output when there is no input signal.

Humidifier adds moisture to the air, which can benefit people with respiratory symptoms or dry skin.
There are several ways to use humidifiers in the home or office, but there are also some risks.
In this article, learn about the benefits of humidifiers, how to use them correctly, and precautions to take.
Dryness and humidity
By adding moisture to the air, humidifiers may be beneficial for several medical conditions.
Dry air can cause moisture to evaporate from the skin and respiratory symptoms to worsen over time. Adding moisture to the air with a humidifier can counteract these problems.
Humidifiers can help people who experience:
dry skin
irritated eyes
dryness in the throat or airways
allergies
frequent coughs
bloody noses
sinus headaches
cracked lips
Five humidifier uses and their benefits
Some people experience respiratory symptoms in the summer months, when the weather is hot, and the air contains more allergens. Air conditioners and fans can circulate dry air through the room, and air conditioners remove any moisture from the air. A humidifier may be beneficial during this season.
However, people are more likely to benefit from a humidifier in the cold months, when cold air dries out the lungs, nose, and lips. Also, some types of central heating can dry out the air indoors.
Benefits of a humidifier may include:
1. Preventing influenza
Authors of one studyTrusted Source noted that humidifiers might reduce the risk of catching the flu. After adding the influenza virus to the air with a simulated cough, researchers found that humidity levels above 40 percent rapidly deactivated virus particles, making them much less likely to be infectious.
2. Making a cough more productive
Dry air can cause a person to have a dry, unproductive cough. Adding humidity to the air can get more moisture into the airways, which can make a cough more productive. A productive cough releases trapped or sticky phlegm.
3. Reducing snoring
Increasing the amount of moisture in the air can also reduce snoring. If the air is dry, a person’s airways are less likely to be sufficiently lubricated, which can make snoring worse.
Adding humidity to the air by running a humidifier at night may help to relieve some symptoms.
4. Keeping the skin and hair moist
Some people notice that their skin, lips, and hair become dry and fragile in the winter.
Many types of heating units pump hot, dry air through the house or office, which can make the skin dry, itchy, or flaky. Cold air outside can also dry out the skin.
Using a humidifier to add moisture to the indoor air may help to reduce the occurrence of dry, cracked skin.
5. Benefits for the home
Moisture from a humidifier can be helpful around the home. Any moisture-loving houseplants may become more vibrant, and wood floors or furniture may last longer. Humidity can also help to prevent wallpaper from cracking and static electricity from building up.
Humid air can also feel warmer than dry air, which could help a person to save money on utility bills in winter months.

Types of humidifiers
While most humidifiers have the same basic function, to add moisture to the air, many types are available:
Steam vaporizers: These use electricity to create steam, which cools before it leaves the unit. However, there is a risk of burning the skin, and people should avoid using steam vaporizers around children.
Ultrasonic humidifier: Instead of electricity, these units use vibrations to vaporize water.
Evaporators: These produce humidity by blowing air past evaporating water.
Impeller humidifiers: These are generally child-friendly and use rotating disks, rather than heat, to vaporize water.
Central humidifiers: A person connects one of these units to the central air conditioning in the home or office to add moisture to the entire space.
Sizes can vary. Console humidifiers are large enough to add moisture to an entire house or office, while personal humidifiers are portable and easy to carry.
What is an Industrial Humidifier?
An industrial humidifier is a system that is capable of providing adequate humidity levels in a manufacturing environment. High-speed production processes add to the heat load in a building, bringing down the humidity. This can lead to a dangerous buildup of static electricity in a plant where dust and other flammable materials may be in the air. Processes such as woodworking, printing, and electronic and microchip fabrication, — which involve gluing, coating, and bonding — benefit from humidity control. Energy efficiency is also a consideration with an industrial humidifier.
Related products include industrial steam humidifiers, as well as electric-powered and gas-fired models. Steam heat exchangers use a heat source for producing steam from tap water or pure water reserves. These are also designed to comply with indoor air quality requirements to ensure proper humidity levels along with clean air for workers.
Industrial humidifiers are also designed as fog systems that integrate with building automation systems. In this configuration, an industrial humidifier system can be integrated above the factory floor, with the moisture released via fog nozzles. This is a viable alternative to humidifying air traveling through ducts, because excessive heat loads can be managed at the source.
An industrial humidifier also can be a contamination control system. It can be capable of utilizing adiabatic humidification to control humidity and airborne particles, and reduce the buildup of electrostatic discharge that, when combined with particulates, can be a health hazard and a cause for major industrial accidents. Along with proper treatment of supply water, an industrial humidification system ensures a safe environment in which to work.
An industrial humidifier can be found in many manufacturing facilities. Plants that make electronic assemblies require humidification, because the air in buildings producing circuit boards and computer equipment must be free of particles. Semiconductor manufacturing is another major application, because integrated circuit printing requires tightly controlled temperatures, along with a relative humidity (RH) of around 35 percent to 45 percent with acceptable tolerances within a range of 1/2 percent to 5 percent RH.
What Does a Dehumidifier Do?
A dehumidifier is an appliance that takes moisture out of the air in your home.
If you or your family members have asthma or allergies, a dehumidifier might help relieve symptoms and make breathing easier.
This article will help you decide whether a dehumidifier is a worthwhile investment for your living space.

Dehumidifier uses and health benefits
You may remember the water cycle from elementary school science: evaporation, condensation, and precipitation. What you might not realize is that the water cycle is always taking place in the air you’re breathing, even when you’re spending time inside.
“Humidity” is a measure of water vapor in the air. Dehumidifiers remove or minimize this water vapor.

How a dehumidifier works
A dehumidifier works by drawing warm air currents into its coils via a fan. The warm air contracts as it’s fed through the refrigerated coils of the machine, and condensation is left inside the dehumidifier.
As this condensation collects, one droplet of water at a time, it falls into a storage tank attached to the dehumidifier. Cooler, drier air is then released back into your home through the other side of the machine.
Your dehumidifier should be able to bring the moisture in the air down to a relative humidity of 30 to 50 percent. Many dehumidifiers come with a meter that measures the relative humidity where it’s placed in your home, and you can set the humidity to the percentage you desire.
Application of Dehumidifiers for Various Industries

1. Food Industry:
   Excess humidity causes condensation and a broad range of hygiene problems in the product. Be it powdered food, spices, processed meat, snack foods confectionery products or breweries, consistent and controlled moisture conditions are necessary. Using dry air from a Desiccant dehumidifier can help in controlling the moisture content, which leads to perfect coating and longer shelf life of the food products.
   
   
2. Lithium Batteries:
   The primary requirement for manufacturing of lithium batteries is a dry room with very low humidity. Lithium is extremely sensitive to moisture; thus, high moisture content leads to a reduction in performance and life of the product. Industrial dehumidifier ensures that the processing areas have the required amount of moisture in the air which is less than 14gms of moisture per kg of dry air.
   
   
3. Pharmaceutical Industry:
   During the processing stage, most of the medicines are in powdered form and are highly hygroscopic. Excess of moisture absorption leads to organic corrosion, biochemical reactions and micro-organism growth on the product. Dehumidifiers help in keeping the required humidity parameters for processing, drying, storing and transportation of medicines.
   
   
4. Cold Stores:
   To prevent flowers, vegetables, fruits, milk and processed foods from deterioration they are cooled and stored in cold store under low moisture conditions. Since the cold stores experience the frequent movement of products, warm air with moisture from outside could enter the store. This results in ice and frost formation on the walls, floors and ceilings on the cold stores. Air curtain using Dehumidified air at the cold store doors helps in controlling the ingress of moisture laden entering the cold rooms.
   
   
5. Defense Industry:
   Military equipment is highly prone to humidity damage when they are stored for long periods. Uncontrolled humidity causes corrosion and malfunctioning of equipment, fungal growth on maps, drawings and bacterial infection on rations. Storage rooms of standard equipment such as trucks, tanks, guns and ammunition require specific humidity levels and controlled temperature. Dehumidifiers help in preventing corrosion on the equipment by keeping humidity levels less than 35%.
   
   
6. Electronic and Semiconductors:
   Components used in assembling or processing of semiconductors are hygroscopic and highly sensitive to excess humidity. Excess moisture results in corrosion of PCB, transistor failures, and condensation on integrated circuits. The RH in semiconductor manufacturing area must be 30% at 20oc. Industrial dehumidifiers also help in protecting the vacuum and EPI equipment.
   
   
7. Turbine Industry:
   Moisture can corrode turbines, boilers, condensers and many other machines when they are kept for maintenance during the layup process. High humidity causes corrosion and rusting on the equipment leading to their malfunctioning. As the repair and downtime costs of these equipment are very high, moisture control becomes essential. Industrial dehumidifiers help in keeping moisture levels low during the storage of the product; thus, preventing corrosion.
   
   
8. Leather industry:
   The Leather is a hygroscopic material; excess moisture leads to the growth of mold and mildew on leather. Without proper humidity control, leather loses its shine, produces the foul smell, loses its strength and starts decomposing. Relative humidity above 40% leads to micro-organism growth that results in decomposition of leather. Dehumidifiers help in providing controlled moisture conditions during the processing of leather products.
   

The role of the combiner box is to bring the output of several solar strings together. Daniel Sherwood, director of product management at SolarBOS, explained that each string conductor lands on a fuse terminal and the output of the fused inputs are combined onto a single conductor that connects the box to the inverter. “This is a combiner box at its most basic, but once you have one in your solar project, there are additional features typically integrated into the box,” he said. Disconnect switches, monitoring equipment and remote rapid shutdown devices are examples of additional equipment.

When hoverboards hit the scene in 2015, they were an immediate success. Also known as self-balancing or two-wheeled boards, these toys can be a fun way to get around. However, many parents began to wonder — just how dangerous are hoverboards?
Shortly after their debut, several manufacturers started selling hoverboard that were not inspected for quality or safety. News reports revealed potential hoverboard dangers — motorized boards spontaneously overheating, catching fire and causing burns. To date, more than 300 of these incidents have been reported to the Consumer Product Safety Commission.
Newer hoverboards don’t pose the same level of fire risk. If you have an older model, visit the Consumer Product Safety Commission to see if there’s been a recall. All hoverboards should be compliant with the UL 2272 safety standard.
However, even if your child has one of the newest models, there are still hoverboard dangers to consider. After all, two-wheeled boards can be difficult to balance on, and falls resulting in injuries are not at all uncommon.
A Look at Hoverboard Injury Statistics
How often does a fall result in a serious hoverboard injury? Statistics from the American Academy of Pediatrics study show that about 26,854 children visited an emergency department with a hoverboard injury during 2015 and 2016. The average age of an injured child was 11, with boys being slightly more common than girls (52 percent of the children seen were boys).
Children were most likely to injure their wrists, forearms and heads. The most common injuries were:
Fractures (40 percent)
Bruises (17 percent)
Strains/sprains (13 percent)
While these hoverboard injury statistics may seem alarming, many other wheeled toys — that have been around much longer — result in trips to the emergency room as well. During the same 2015 to 2016 time period, skateboards caused almost 121,400 injuries.
How Does a Hoverboard Work?
Do you ever daydream about the future? What might the world be like in a few decades? Could there be cars without drivers? Trucks that fly? Boats driving on land and water?
You may already know about self-driving cars and self balancing hoverboard. But what about hoverboards? Picture it: You’re flying down the sidewalk on an object that looks like a skateboard without wheels. You turn a corner, swerve around other people, and get home from school in record time, without ever touching the ground!
Does this sound like science fiction? Think again! Hoverboards are already a reality. But how do they work?
The “hoverboards” you may have seen friends riding are actually self-balancing scooters. These scooters don’t hover above the ground. Instead, they use two wheels to get around.
Okay, so why are they called HOVERboards? People call self-balancing scooters “hoverboards” because of the sensors that help them stay balanced. The board’s sensors find out which way the rider is leaning. They then tell the board’s motor how fast and in what direction to spin. That’s how this “hoverboard” stays balanced!
Self-balancing scooters rely on a battery pack for power, and each one contains a logic board. You can think of this as the “brain” of the hoverboard. It processes things like the speed of the board and the tilt of its wheels. The logic board also manages settings. For example, hoverboards can be put in beginner mode to limit their maximum speed.
If you’re not satisfied with a self-balancing scooter, have no fear! Hoverboards with no wheels are coming soon—and they’ll truly float above the ground. Some of these hoverboards may use the science of magnets. They will have hover engines that contain electrically charged magnets, or electromagnets. These use an inductor to create a powerful magnetic field. When the magnetic field is strong enough, the board will float in the air!
A company called Omni has also created a hoverboard that uses propellers. Their design even holds the Guinness World Record for the farthest flight by hoverboard. It traveled 275.9 meters (905.2 feet). The Omni hoverboard is expected to hit the shelves in late-2021.
Would you like to travel by hoverboard? Do you see a future of these vehicles zooming through the streets? Or do you imagine even better ways of getting around? Anything is possible!
What is an all terrain hoverboard?
These are similar to the original hoverboards in how they work, but they are generally bigger, stronger and more durable. Instead of being a traditional 6.5 inch hoverboard, most have 8.5 or 10 inch wheels. Instead of solid rubber tires (which are only suitable for smooth ground) they have pneumatic tires for travelling safely and smoothly over a variety of terrains including grass, gravel and sand for a more exciting riding experience. This makes them far more versatile and more fun because you can use them almost anywhere. Most all terrain hoverboards even come with builtin bluetooth hoverboard capability AND they’re suitable for kids and adults of all ages!
Back in 2015 hoverboards hit the market with a bang. These two wheeled self balancing scooters became THE hot product of the year, and although they hit a few blips along the way (inferior quality models with cheap batteries caused some fire problems in the early days), they have only gone from strength to strength since then. In 2016 Underwriter Laboratories introduced the UL 2272 hoverboard certification, so hoverboards are now safer and higher quality than ever. In 2021 technology has advanced to the stage where we now have all terrain hoverboards that can travel over grass, sand, gravel and more (the traditional hoverboards that first came on the market were only suitable for smooth pavement). In this article I’m going to be discussing which is the best off road hoverboard available today.
Hoverboard? Still in the Future
The hoverboard is fiction, the vision of screenwriters who created the film about Marty McFly, a teenager who travels from 1985 to Oct. 21, 2015, and uses a floating skateboard to flee a gang of bullies.
The movie had other futuristic items, like flying cars and self-tying shoes, but none touched the imagination as much as the hoverboard. For the last 25 years, garage tinkerers, physics professors and top engineers at Google have been trying to make one.
Inside a drab office park here in Northern California, Greg and Jill Henderson are working on the latest effort. On a recent visit the couple allowed a reporter to stand atop a noisy magnetic skateboard that can float above a copper surface.

It hovers about an inch above the ground. But when the 190-pound visitor stood atop the 100-pound board, one gentle push was enough to send him spinning across the room over a cushion of air.
The Hendersons have poured their life savings into hover technology and are hoping to create new industries based on this science.
Dustin Rubio, 39, an electrician who grew up skateboarding and saw “Back to the Future Part II” when he was a teenager, is not thinking quite that big.
This year, Mr. Rubio turned “a leaf blower, some plywood, some plastic and duct tape” into a small hovercraft that his daughters used to glide down the driveway at his home in Napa, Calif. “I was like I’m just gonna make something funny and see if it works,” he said.
Unfortunately, his invention is not really a new hoverboard. Bob Gale, who wrote the “Back to the Future” trilogy, said that, in his imagination anyway, the hoverboard floats on a magnetic field similar to magnetic levitation trains.Continue reading the main story

This has been extremely difficult, mostly because of something called Earnshaw’s theorem, which states, more or less, that repelling magnets are tough to balance. One way is to use a track that would hold the magnetic skateboard in place, but what self-respecting skateboarder wants to be constrained to a track?
Superconductors can also levitate things. In 2011, a research group directed by Alain Sacuto, a physics professor at the Université Paris Diderot, used smoking-cold superconductors to levitate a liquid-nitrogen-filled skateboard that he and others rode across a five-meter magnetic rail.
In March, the website Funny or Die released a video that seemed to show the skateboarder Tony Hawk on a real hoverboard. Mr. Hawk later apologized for misleading fans.
“As early as this morning I had three emails from people: Is this real? Can I buy it?” Rachel Goldenberg, who produced the video, said on Monday.
If you had to time-travel back to 1989 and place a couple of bets on who might invent the hoverboard, Rich DeVaul would have been a good wager. Mr. DeVaul is a senior engineer at Google X, the company’s research division. He is also a longboard skater and a snowboarder.

So what is a stand up pouch? Simply put, it’s bag/pouch that has the ability to stand on its own. The original stand up pouch design was actually patented in 1968. However, it wasn’t until the patent expired did the stand up pouch revolution begin. The stand up pouch design and construction have evolved over the years to include innovative design features like the reclosable zipper, convenient tear notches for easy opening, and some styles have a window for easy viewing. Today, the stand up bag is the go-to packaging choice for many well-known brands. Companies are using these airtight bags for candy packaging, coffee packaging, tea packaging, pet packaging, beauty product packaging, and more.
 
A stand up pouch is made of multiple layers of barrier materials that have been laminated together to create one continuous sheet. The barrier materials and bag construction determine the durability and shelf life of your packaging. The chosen materials also determine the potential risk of bag punctures, leaks, and tears. Therefore, choosing a higher quality spout bag will ultimately mean fewer problems down the road. There are typically 2-3 layers in the construction of a stand up pouch. There is an outer layer, a middle layer, and an inner layer. Each layer provides a barrier of protection to protect and preserve the contents from environmental elements including moisture, UV light, oxygen, and external odors.
Flexible packaging is typically made from plastic or paper, which is considerably lighter than glass and cardboard boxes. So, whether your customers are heading to work, on holiday, or just lounging about at home – your customers can enjoy your goods any time they like.
Furthermore, since the packaging is less rigid, it takes up far less space. So it can be stored in small compartments,central seal bag, lockers, and small pantries. Again, even greater convenience for your customers!
 
We offer classic Kraft stand up pouches, as well flat bottom bag and various other designs of Kraft paper pouches. We also have pouches made partially of Kraft paper but incorporating a window or a whole clear side which allows the consumer to see exactly what they are buying while that product remains sealed for freshness and protected. Various designs available in our store also include Kraft resealable pouches such as Kraft zipper pouch bag.
For extra protection, we have pouches that combine aluminium foil with Kraft paper. Such construction ensures the strongest protection and durability, without sacrificing the classic, traditional look of the 3 side seal bag.

The material properties of the membrane dominate the performance of a RO process. The emergence of nano-technology and biomimetic RO membranes as the futuristic tools is capable of revolutionizing the entire RO process. Hence the development of nano-structured membranes involving thin film nano-composite membranes, carbon-nanotube membranes and aquaporin-based membranes has been focussed in detail. The problems associated with a RO process such as scaling, brine disposal and boron removal are briefed and the measures adopted to address the same have been discussed.
MWCNT synthesized by catalytic chemical vapour deposition13,14 have been widely studied due to their fascinating chemical and physical properties and among all nanocarbon materials, they can be mass-produced for commercially available applications, such as the electrode additives in high performance lithium ion batteries15. Interestingly, while the structure of the fully aromatic PA-based commercial ro membrane derived from m-phenylendiamine (MPD)-trimesoyl chloride (TMC) is constrained due to its stoichiometry; the addition of MWCNT can significantly vary their performance due to their unique features such as dispersability diameter, length, straightness and chemical functionalities, among many others. Therefore, although these past reports acknowledge the key role of MWCNT in aromatic PA nanocomposite membranes, still little attention has been devoted to the mechanisms related to the improvement of flow rate, selectivity and chlorine tolerance2. Carbon nanotubes inducing chlorine tolerance are particularly interesting because chlorine sensitivity has been recognized as a major drawback of PA-based RO membranes16,17. During long-term operation, chlorine is often added as a pre-treatment to reduce algae biofouling18 and is particularly needed for drinking water purification. Moreover, high-concentration short-term exposure to chlorine is also common during domestic nf membrane backwashing. For these reasons, several studies have been carried out and the degradation mechanism of aromatic PA membranes during chlorine exposure is relatively well-known19,20. Recently, our group demonstrated that the addition of MWCNT to rubber can considerably reduce the chlorine-induced degradation of the polymer matrix21. Although the degradation mechanism of rubber by chlorine is different from that of PA, particularly due to the lack of hydrolysis, covalent chlorination is a common problem for both polyamide and rubber. For rubber, we found that MWCNT effectively restricted the adsorption of chlorine within the polymer matrix, thus resulting in a limited exposure of the polymer to this reactive reagent and thereby decreasing the oxidative degradation. For these reasons, we believe MWCNT are not only promising composite fillers with chlorine protective properties, but might also help to provide mechanical robustness to PA-based RO membranes. D- and G- peaks could be observed, indicating a homogenous mixture and a high content of MWCNT, which is not common in these type of nanocomposites, because the MWCNT are prone to aggregation even when loading at low concentrations. Commercial NF membrane exhibited a lower contact angle; however in this case, the presence of wetting additives or a surface treatment is likely responsible for this phenomena. The method used to synthesize the MWCNT·PA nanocomposite relies on the transport of the MWCNT to the organic/aqueous interface during polymerization23. Indeed, the presence of a limited amount of anionic surfactant has been recently reported to improve PA membrane formation, resulting in better performance24. This is most likely due to a reduction of the oil/water interfacial tension, a process that in our case is also promoted by the small amount of surfactant that provides amphiphilicity to the nanotubes It is important to emphasize that we did not used covalent functionalization of MWCNT, in contrast to some previous reports8,11.

You’ve heard the term before; tactical backpack.  It’s hard to avoid, in fact.  It’s impossible to deny that “tactical” packs are a trend that isn’t going away any time soon in the carry world.  In fact, at this point it may not even be a trend, but one of the pillar groups.  How did this happen?  Well, as long as there has been military, there have been people who want to use the gear for their civilian lives (the common day tshirt is a perfect example of gear popularized by military design and use).  And just to be clear, civilians using military gear is awesome.  As long as you’re not going around claiming you’re a soldier when you’re not.  That’s not cool.  Otherwise, feel free to enjoy the benefits of these awesome packs and gear.  In one way or another, you’ve already paid for them via taxes!
As the title states, this is a breakdown of tactical thigh bag for beginners.  An introduction.  So let’s dig in and explore what makes one functional tactical pack great versus a cheap knock-off for fashion’s sake.
We’re material geeks over here.  And generally military tactical packs all should be made from quality fabrics that can take a beating.  As a general rule of thumb, they should be made from 500D – 1200D CORDURA nylon fabric (or better).  Not 200D.  Not Kodra.  Not polyester.  This is an easy one.  Some packs may even use nicer materials, such as X-Pac (VX) fabric.  Usually these fabrics are heavier (not always), but they’re weather resistant and take a fall down a mountain or twenty.
For both professional and recreational applications, tactical vest offer carefully structured layouts that carry comfortably and keep gear secure, even when packed with heavy loads.
We’ve examined and reviewed options from across the tactical backpack market and determined which packs rank among the best in 2021.
Scroll through our list to view our picks, or jump ahead to the specific category that you’re interested in.
For both professional and recreational applications, tactical vest offer carefully structured layouts that carry comfortably and keep gear secure, even when packed with heavy loads.
We’ve examined and reviewed options from across the tactical backpack market and determined which packs rank among the best in 2021.
Scroll through our list to view our picks, or jump ahead to the specific category that you’re interested in.A backpack is a bag for holding things. It’s hard to make that tactical, since one bag is very like another. When discussing turning a piece luggage into a lean, combat-equipped fighter, the first question that must be answered is: How? It’s a simple matter to put a few MOLLE straps onto a rucksack and call it battle-ready, but that does not fit the bill. True tactical packs are build with missions in mind, giving operators a lot of customization of the inside depending on if they’re doing recon, hunter/killer missions, sabotage, or simply going on a day hike. Real tactical suits also step up the durability to the point that they’re nigh indestructible, and are replete with hidden stash spots for secreting away a weapon, a jump drive with the Death Star plans, or a message to the wetwork pro who will find your body.Going in an asymmetrical direction, the Javelin looks a little awkward at first, but the design is intended to land at your body’s natural load-bearing points for an even distribution across your entire back to prevent walking cock-eyed. Built with 1000 Denier cordura and neoprene handles, the large number of small compartments makes this a good field bag for medical, electrical, demolition, or photography work. Top or side access gives it a convertibility that’s welcome in a tactical bag. You’ll never stray far from quality with 5.11’s tactical belt. Though their Rush line gets more attention, the more basic All Hazards Prime has a straighter build. Constructed using input from MACTAC (Multi-Assault Counter-Terrorism Action Capabilities) instructors, the layout is made specifically to give you access to all your gear, and keep it precisely where you expect it to be. Should you drop something, hi-vis orange lining makes it pop out, day or night.