Spumele metalice compozite sunt destul de rezistente pentru a transforma un glonț care străpunge armătura în praf la impact
Prezentăm un citometru de impedanță microfluidică care poate fi purtat pe bandă flexibilă cu cititor de smartphone on-line pentru numărarea și analiza portabilă a biomarkerilor
Combinația dintre greutatea redusă, rezistența ridicată și conductivitatea ridicată este atrăgătoare pentru aplicații precum conductarea cablurilor și a electrozilor, a spus Kabbani. „Materialul de peleți este mai puternic și mai ușor decât electrozi de grafit comercial și ar putea fi promițător pentru aplicații de stocare electrică cu densități mari de energie și putere”, a spus el.”Aceasta este prima dată când cineva le-a făcut la temperatura camerei și fără prea multă presiune”, a spus el. „De obicei, aceste tipuri de materiale necesită sinterizare (un proces care utilizează presiune sau căldură pentru a forma solide fără a le topi) la temperaturi de peste 1000 ° C pentru a produce pelete puternice. În acest caz, mecanochemistry la scară nanometrică ne-a salvat o mulțime de energie și de bani
| Posted: Mar 22, 2018 | |
Making shiny pellets of graphite from functionalized graphene (w/video)(Nanowerk News) A report in Carbon („Consolidation of functionalized graphene at ambient temperature via mechano-chemistry”) shows how chemically altered graphene powder can be pressed into a lightweight, semiporous solid that retains many of the strong and conductive qualities of graphite, the form of carbon found in pencils, lubricants and many other products that normally requires high-temperature processing to make. |
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| Mohamad Kabbani, a former graduate student of Rice materials scientist Pulickel Ajayan and lead author of the paper, demonstrated the environmentally friendly, scalable process can be done in minutes by hand by grinding chemically modified graphene into a powder and using a hand-powered press to squeeze the powder into a solid pellet. | |
| Kabbani previously showed how carbon nanotubes could be turned into graphene with a mortar and pestle rather than harsh chemicals. This time, he and his colleagues demonstrated how to make a battery-sized pellet, but the graphene powders with chemical functionalities attached to it can be pressed into any form. Kabbani said the material could be suitable for structural, catalytic, electrochemical and electronic applications. | |
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| Researchers at Rice University consolidated functionalized graphene at room temperature by first crushing graphene powder and then pressing it into pellets. Chemically altering the graphene powder with carbon, oxygen and hydrogen provided a way to bind the graphene into a three-dimensional solid under pressure. (Image: Ajayan Research Group/Rice University) | |
| “This is the first time anyone’s made these at room temperature and without very high pressure,” he said. “Usually these kind of materials require sintering (a process that uses pressure or heat to form solids without melting them) at temperatures above 1,000 degrees Celsius to produce strong pellets. In this case, mechano-chemistry at the nanoscale saved us a lot of energy and money.” | |
| The process began with two sets of functionalized nanotubes, one with carboxylic acid and the other with hydroxyl molecules. Once crushed to combine them either by hand or machine, they are placed in a lab-scale hydraulic press and subjected to 5 tons of pressure. The functional groups cross-linked the graphene sheets to each other, and even though no liquids were involved, they produced a tiny amount of water as a byproduct of the reaction, Kabbani said. | |
| The pellets remained stable when placed in hot water for five hours, even when stirred; this confirmed the interlocking of the graphene sheets within, the researchers reported. | |
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| Scanning electron microscope images show graphene flakes before compression, at left, with individual flakes outlined, and well-connected graphene sheets after compression at right. Scale bar is 20 nanometers. (Image: Ajayan Research Group) | |
| The combination of light weight, high strength and high conductivity is appealing for applications such as conducting cables and electrodes, Kabbani said. “The pellet material is stronger and lighter than commercial graphite electrodes and could be promising for electrical storage applications with high energy and power densities,” he said. |
| Source: Rice University |
Pe partea MP5, MI primește mîna tactică MI-MP5M M-LOK pentru modelul SMK / SBR standard HK MP5 și manevra tactică MI-SP89M M-LOK pentru HK MP5K-PDW de tip SMG / SBR și HK SP89 arme de foc de tip pistol de numai 9 mm. Pe latura CZ Scorpion, MI v-ati acoperit cu MI-CZ11.5M, MI-CZ6.75M si MI-CZ4.25M, impreuna cu instrumentul de indepartare a nuciului de butoi MI-CZSW, de care aveti nevoie.
Got a HK MP5-type, HK MP5K-PDW-type, or CZ Scorpion 9mm submachine gun (SMG)/short barreled rifle (SBR) or carbine in need of some combat/tactical accessorizing? If so, Midwest Industries has some new M-LOK tactical handguards/forend rail tubes that can help you do it. On the MP5 side, MI’s got the MI-MP5M M-LOK tactical handguard for the standard HK MP5-type SMG/SBR, and the MI-SP89M M-LOK tactical handguard for the HK MP5K-PDW-type SMG/SBR and HK SP89 semi-auto-only 9mm pistol-type firearms. On the CZ Scorpion side, MI’s got you covered with the MI-CZ11.5M, MI-CZ6.75M, and MI-CZ4.25M, along with the MI-CZSW barrel nut removal tool, which you’re gonna’ need.
All of the MI M-LOK handguards are made from hard-coat-anodized 6061 aluminum, and integrate perfectly visually with the guns. They look really good. They should also prove durable. The handguards all feature the maximum amount of mounting slots possible, “M-Lok slots at the 45 degree position for perfect light location”, and anti-rotation QD sling swivel sockets. Oh, and they’re quick and easy to install and remove. Basically, they’re awesome.
Anyway, check out DR’s video below, featuring MI’s Pete Bratz taking us through them. Pay particularly close attention to the 45-angle M-LOK slots for tactical white lights.
Company Contact Info:
Midwest Industries, Inc (MI)
W292S4498 Hillside Rd.
Waukesha, WI 53189
Phone: 262-896-6780
Email Contact Page: http://www.midwestindustriesinc.com/index.cfm?fuseaction=page.display&page_id=33
Website: http://www.midwestindustriesinc.com
Un nou dispozitiv de precizie va ajuta viitoarele forțe de pe câmpul de luptă să identifice personalul ca prieten sau dușman pe câmpul de luptă
Tehnologiile purtătoare care conțin senzori pot salva vieți;filmul este purtat în interiorul armurii corpului, în interiorul frontal și în interiorul spatelui și acesta este modulul care poate detecta orice fel de eveniment patrunzator
Procesul de piroliză a fost experimentat utilizând două tipuri de surse de încălzire, și anume convenționale și microunde. Deșeul de plastic din polistiren (PS) a fost utilizat ca materie primă într-un reactor discontinuu atât pentru piroliza convențională (piroliză lentă), cât și pentru piroliza în microunde. Sa studiat efectul raportului dintre carbonul activ și polistiren asupra (i) randamentului de ulei, gaz și reziduuri (ii) temperatura de reacție (iii) timpul de reacție. Calitatea uleiului din piroliza polistirenului a fost evaluată pentru posibila aplicabilitate în producția de combustibil. Puterea cu microunde de 450 W și raportul polimer cu cărbune activ de 10: 1, a condus la cel mai mare randament al uleiului de 93,04% în greutate cu o valoare de încălzire mai mare de 45 MJ kg -1și o viscozitate cinematică de 2,7 cSt. Încălzirea cu microunde în comparație cu metoda de încălzire convențională prezintă o temperatură de reacție și un timp de 330 ° C în 5,5 minute, în timp ce în sistemul de încălzire convențional a fost de 418 ° C în 60 de minute
PSW was rapidly processed in microwave pyrolysis.
Temperature measurement using modified chromel-alumel thermocouple.
A reaction temperature of 330 °C in 5.5 min.
Viscosity of the oil was 2.7 cSt.
Pyrolysis process was experimented using two types of heating source, namely conventional and microwave. Polystyrene (PS) plastic waste was used as feedstock in a batch reactor for both the conventional (slow pyrolysis) and microwave pyrolysis. The effect of activated carbon to polystyrene ratio on (i) yield of oil, gas and residues (ii) reaction temperature (iii) reaction time were studied. Quality of oil from pyrolysis of polystyrene were assessed for the possible applicability in fuel production. Microwave power of 450 W and polymer to activated carbon ratio of 10:1, resulted in the highest oil yield of 93.04 wt.% with a higher heating value of 45 MJ kg−1 and a kinematic viscosity of 2.7 cSt. Microwave heating when compared to conventional heating method, exhibits a reaction temperature and time of 330 °C in 5.5 min, whereas in conventional heating system it was 418 °C in 60 min. The gas chromatography-mass spectrometry analysis of liquid oil from microwave pyrolysis predominantly yields alkenes of 8.44 wt.%, α-methyl styrene 0.96 wt.%, condensed ring aromatics 23.21 wt.% and benzene derivatives 26.77 wt.% when the polystyrene to activated carbon ratio was 10:1. Significant factor of using microwave heating is the amount of energy converted (kWh) is lesser than conventional heating.
Graphene, care sunt foi din carbon, atrage interesul larg din partea multor oameni de știință ca un candidat puternic pentru noua generație de materiale electronice datorită proprietăților lor unice. Dezvoltarea unei metode fiabile, care permite alinierea perfectă a moleculelor sau a ansamblurilor moleculare pe o suprafață de grafen, poate conduce la stabilirea proprietăților electrice ale grafenului și la îmbunătățirea performanțelor dispozitivelor electronice pe bază de grafen. Deși a fost studiat pe scară largă în ultimii ani, dezvoltarea unor nanostructuri moleculare bine aliniate exclusiv de-a lungul unei direcții dorite este încă dificilă. Acest lucru se datorează faptului că suprafața grafenului are o simetrie de trei ori, echivalentă termodinamic unul cu celălalt, ceea ce face dificilă alinierea moleculelor într-o direcție orientată.
| Posted: Mar 22, 2018 | |
Scientists control molecular alignment on a graphene surface(Nanowerk News) A group of scientists at Nagoya University have developed a simple and powerful method to construct perfectly unidirectional molecular assembly structures on graphenes, according to a study reported in the journal Scientific Reports („Unidirectional molecular assembly alignment on graphene enabled by nanomechanical symmetry breaking”). Discovered accidentally during other research, the method relies on a common laboratory tool, atomic force microscopy (AFM), to control molecular alignment. |
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| Molecular assemblies on graphene grow in perfect orientation by atomic force microscopy (AFM) tip scanning. (Image: Nagoya University) | |
| Graphene, which are sheets made out of carbon, is attracting wide interest from many scientists as a powerful candidate for the next generation of electronics materials due to their unique properties. The development of a reliable method that enables the perfect alignment of molecules or molecular assemblies on a graphene surface may lead the way to tune the electric properties of graphene, and to improve the performance of graphene-based electronic devices. Although widely studied in recent years, the growth of well-aligned molecular nanostructures exclusively along a desired direction is still difficult. This is because the graphene surface has three-fold symmetry, which are thermodynamically equivalent to each other, thus making it difficult to align the molecules in an oriented direction. | |
| To resolve this problem, a team led by Dr. Yuhei Miyauchi and Professor Kenichiro Itami of the JST-ERATO Itami Molecular Nanocarbon Project and the Institute of Transformative Bio-Molecules (ITbM), focused on the physical changes induced by AFM tip scanning. AFM, a technique mainly used for analyzing surfaces, produces images showing the surface unevenness of samples by sliding a probe tip over the surface area. The team suspected that tip scanning modifies the thermodynamical conditions on the graphene surface and affects the direction of molecular alignment. | |
| The team investigated how AFM tip scanning leads to changes in molecular alignment on the graphene surface. They used sodium dodecyl sulfate (SDS), a common surfactant molecule, as a model molecule. Studies have shown that SDS forms ribbon-like assembles on the graphene surface. | |
| Using a microsyringe pump, the SDS solution was slowly injected into a multilayer of graphene in a water droplet. The team compared how the SDS molecules adhered to the graphene, a process called adsorption (not be confused with absorption), with and without AFM tip scanning. | |
| An AFM height image recorded 1 hour after SDS injection showed random unevenness on the surface, which indicates random adsorption of SDS molecules on the graphene surface. After 15 minutes of intense AFM scanning, the SDS adsorption morphology drastically changed and many ribbon-like molecules were observed. This phenomenon indicated that the strength and direction of AFM tip scanning affects the orientation of the generated SDS ribbons. | |
| “We discovered this phenomenon accidentally when we were carrying out another research project,” says Dr. Liu Hong, a postdoctoral researcher who mainly conducted the experiments. “We noticed that looking at the images of AFM, the SDS ribbon grew in the same oriented direction by AFM tip scanning.” | |
| “We genuinely wanted to clarify this surprising phenomena,” says Yuhei Miyauchi, a group leader of the JST-ERATO project. | |
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| Images of experimental setup and AFM images. (Image: Nagoya University) (click on image to enlarge) | |
| The team analyzed the correlation between the AFM scanning direction and the observed ribbon orientation. They discovered that the SDS ribbons grew easily when the relative angle between the ribbon growing axis and the scan direction is larger. In addition, computational calculations suggested that adsorbed SDS molecules are actually removed when they are forced to rotate under the AFM scanning conditions. Adsorbed SDS molecules with a relatively large angle to the AFM tip scan direction are rotated and are easily removed. Therefore, the molecules adsorbed with small angles to the AFM tip scan direction act as the nuclei and grow to become the SDS ribbon. | |
| On the basis of their understandings, the team tried to construct perfectly aligned SDS molecular assemblies on graphene. | |
| “The most difficult part of this research was how to control the growth and direction of SDS ribbons with precision,” says Hong. “Once the SDS ribbons were grown, their orientations did not change under the AFM scanning conditions. We had to perform rapid AFM scans in time just after that very moment where SDS molecules are injected into the water on the graphene surface.” | |
| Under finely tuned AFM scanning conditions, they succeeded in constructing individual one-dimensional molecular assemblies, which are aligned along a selected symmetry axis of the graphene lattice. | |
| “In AFM analysis, the dynamical mechanical effects to the sample by AFM tip scanning have been considered to be unfavorable,” says Dr. Taishi Nishihara, a postdoctoral researcher who conducted the statistical analyses and analyzed the mechanism of this experiment. “Our findings on the hidden usefulness of the effects induced by AFM tip scanning may also provide insight to other researchers in various related fields.” | |
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| Relationship of the total length of the SDS ribbons and the ribbon-scan angle and AFM images. (Image: Nagoya University) (click on image to enlarge) | |
| “The best part of this research is that we were able to show that the AFM scan can induce the ‘symmetry breaking’ effect of the molecular pattern on graphene,” says Hong. “It can be very important for the growth of anisotropic molecular patterns on two-dimensional (2D) materials, such as super lattices, which are now essential in both academic and industrial research.” | |
| “Our concept of breaking the surface symmetry can be applicable for various purposes such as generating molecular circuits in molecular electronics and controlling cell chemotaxis in bioscience,” says Miyauchi. | |
| “We hope that our discovery will lead to a distinctive breakthrough in not only chemistry but in related fields that involve molecular nanostructures and their alignment,” says Itami, the director of the JST-ERATO project and center director of ITbM. |
| Source: Nagoya University |
Sistemul, bazat pe materiale relativ noi de suprafață, numit cadre metalice organice (MOF), poate extrage apă potabilă chiar și din cel mai uscat aer de deșert, spun cercetătorii, cu o umiditate relativă de până la 10 procente. Metodele actuale de extragere a apei din aer necesită niveluri mult mai ridicate – 100% umiditate pentru metodele de recoltare a ceții și peste 50% pentru sistemele de refrigerare bazate pe rouă, care necesită și cantități mari de energie pentru răcire. Astfel, noul sistem ar putea umple eventual o nevoie nesatisfăcută de apă chiar și în regiunile cele mai uscate din lume.
Făcând un dispozitiv de testare pe un acoperiș la Universitatea Arizona de Stat din Tempe, Wang spune că echipa „a fost testată pe teren într-un loc reprezentativ pentru aceste zone aride și a arătat că putem recolta apa, chiar și în zonele de aburi subteroar
| Posted: Mar 22, 2018 | |
In field tests, device harvests water from desert air(Nanowerk News) It seems like getting something for nothing, but you really can get drinkable water right out of the driest of desert air. |
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| Even in the most arid places on Earth, there is some moisture in the air, and a practical way to extract that moisture could be a key to survival in such bone-dry locations. Now, researchers at MIT have proved that such an extraction system can work. | |
| The new device, based on a concept the team first proposed last year, has now been field-tested in the very dry air of Tempe, Arizona, confirming the potential of the new method, though much work remains to scale up the process, the researchers say. | |
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| Researchers at MIT have developed a new device that is able to extract moisture from very dry air. (Image: MIT) | |
| The new work is reported today in the journal Nature Communications („Adsorption-based atmospheric water harvesting device for arid climates”) and includes some significant improvements over the initial concept that was described last year in a paper in Science, says Evelyn Wang, the Gail E. Kendall Professor in the Department of Mechanical Engineering, who was the senior author of both papers. MIT postdoc Sameer Rao and former graduate student Hyunho Kim SM ’14, PhD ’18 were the lead authors of the latest paper, along with four others at MIT and the University of California at Berkeley. | |
| Last year’s paper drew a great deal of attention, Wang says. “It got a lot of hype, and some criticism,” she says. Now, “all of the questions that were raised from last time were explicitly demonstrated in this paper. We’ve validated those points.” | |
| The system, based on relatively new high-surface-area materials called metal-organic frameworks (MOFs), can extract potable water from even the driest of desert air, the researchers say, with relative humidities as low as 10 percent. Current methods for extracting water from air require much higher levels – 100 percent humidity for fog-harvesting methods, and above 50 percent for dew-harvesting refrigeration-based systems, which also require large amounts of energy for cooling. So the new system could potentially fill an unmet need for water even in the world’s driest regions. | |
| By running a test device on a rooftop at Arizona State University in Tempe, Wang says, the team “was field-testing in a place that’s representative of these arid areas, and showed that we can actually harvest the water, even in subzero dewpoints.” | |
| The test device was powered solely by sunlight, and although it was a small proof-of-concept device, if scaled up its output would be equivalent to more than a quarter-liter of water per day per kilogram of MOF, the researchers say. With an optimal material choice, output can be as high as three times that of the current version, says Kim. Unlike any of the existing methods for extracting water from air at very low humidities, “with this approach, you actually can do it, even under these extreme conditions,” Wang says. | |
| Not only does this system work at lower humidities than dew harvesting does, says Rao, but those systems require pumps and compressors that can wear out, whereas “this has no moving parts. It can be operated in a completely passive manner, in places with low humidity but large amounts of sunlight.” | |
| Whereas the team had previously described the possibility of running the system passively, Rao says, “now we have demonstrated that this is indeed possible.” The current version can only operate over a single night-and-day cycle with sunlight, Kim says, but “continous operation is also possible by utilizing abundant low-grade heat sources such as biomass and waste heat.” | |
| The next step, Wang says, is to work on scaling up the system and boosting its efficiency. “We hope to have a system that’s able to produce liters of water.” These small, initial test systems were only designed to produce a few milliliters, to prove the concept worked in real-world conditions, but she says “we want to see water pouring out!” The idea would be to produce units sufficient to supply water for individual households. | |
| The team tested the water produced by the system and found no traces of impurities. Mass-spectrometer testing showed “there’s nothing from the MOF that leaches into the water,” Wang says. “It shows the material is indeed very stable, and we can get high-quality water.” | |
| „This technology is fantastic, because of the practical demonstration of an air-cooled water harvesting system based on MOFs operating in a real desert climate,” says Yang Yang, a professor of materials science and engineering at the University of California at Los Angeles, who was not involved in this work. | |
| “This provides a new approach to solving the problem of water scarcity in arid climates,” Yang says. “This technology, if one can further increase its production capacity, can have a real impact in areas where water is scarce, such as southern California.” |
| Source: By David L. Chandler, MIT |
Textilul constă din fire piezoelectrice țesute împreună cu fire conducătoare electric. Un fir piezoelectric este alcătuit din 24 de fibre, fiecare fiind subțire ca un fir de păr, fiecare fibră având un miez conductiv electric, înconjurat de un polimer izolator și piezoelectric. În timpul fabricării, țesătura este expusă unui câmp electric ridicat, care determină încărcarea pozitivă și negativă a polimerului într-un mod ordonat. Atunci când textilele sunt apoi întinse sau expuse la presiune, deformarea fibrelor determină o reorganizare a distribuției de sarcină, generând astfel o tensiune electrică. Firele conducătoare de electricitate sunt necesare pentru a forma un circuit închis prin care poate curge un curent electric.au dezvoltat o țesătură care transformă energia cinetică în energie electrică
| Posted: Mar 22, 2018 | |
Electric textile lights a lamp when stretched(Nanowerk News) Working up a sweat from carrying a heavy load? That is when the textile works at its best. Researchers at Chalmers University of Technology have developed a fabric that converts kinetic energy into electric power, in cooperation with the Swedish School of Textiles in Borås and the research institute Swerea IVF. The greater the load applied to the textile and the wetter it becomes the more electricity it generates. The results are now published in the Nature Partner journal Flexible Electronics („Energy harvesting textiles for a rainy day: woven piezoelectrics based on melt-spun PVDF microfibres with a conducting core”). |
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| Chalmers researchers Anja Lund and Christian Müller have developed a woven fabric that generates electricity when it is stretched or exposed to pressure. The fabric can currently generate enough power to light an LED, send wireless signals or drive small electric units such as a pocket calculator or a digital watch. | |
| The technology is based on the piezoelectric effect, which results in the generation of electricity from deformation of a piezoelectric material, such as when it is stretched. In the study the researchers created a textile by weaving a piezoelectric yarn together with an electrically conducting yarn, which is required to transport the generated electric current. | |
| „The textile is flexible and soft and becomes even more efficient when moist or wet,” Lund says. „To demonstrate the results from our research we use a piece of the textile in the shoulder strap of a bag. The heavier the weight packed in the bag and the more of the bag that consists of our fabric, the more electric power we obtain. When our bag is loaded with 3 kilos of books, we produce a continuous output of 4 microwatts. That’s enough to intermittently light an LED. By making an entire bag from our textile, we could get enough energy to transmit wireless signals.” | |
| The piezoelectric yarn is made up of twenty-four fibres, each as thin as a strand of hair. When the fibres are sufficiently moist they become enclosed in liquid and the yarn becomes more efficient, since this improves the electrical contact between the fibres. The technology is based on previous studies by the researchers in which they developed the piezoelectric fibres, to which they have now added a further dimension. | |
| „The piezoelectric fibres consist of a piezoelectric shell around an electrically conducting core,” Lund says. „The piezoelectric yarn in combination with a commercial conducting yarn constitute an electric circuit connected in series.” | |
| Previous work by the researchers on piezoelectric textiles has so far mainly focused on sensors and their ability to generate electric signals through pressure sensitivity. Using the energy to continuously drive electronic components is unique. | |
| „Woven textiles from piezoelectric yarns makes the technology easily accessible and it could be useful in everyday life. It’s also possible to add more materials to the weave or to use it as a layer in a multi-layer product. It requires some modification, but it’s possible,” Lund says. | |
| The researchers consider that the technology is, in principle, ready for larger scale production. It is now mainly up to industrial product developers to find out how to make use of the technology. Despite the advanced technology underlying the material, the cost is relatively low and is comparable with the price of Gore-Tex. Through their collaboration with the Swedish School of Textiles in Borås the researchers have been able to demonstrate that the yarn can be woven in industrial looms and is sufficiently wear-resistant to cope with the harsh conditions of mass production. | |
More about: The textile that generates electricity |
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| The textile consists of piezoelectric yarns woven together with electrically conducting yarns. A piezoelectric yarn is made up of 24 fibres each as thin as a strand of hair, with each fibre having an electrically conducting core surrounded by an insulating and piezoelectric polymer. During manufacture the fabric is exposed to a high electric field, which causes positive and negative charges in the polymer to be separated in an orderly manner. When the textile is then stretched or exposed to pressure, the deformation of the fibres causes a reorganisation of the charge distribution, thus generating an electrical voltage. The electrically conducting yarn is required to form a closed circuit through which an electric current can flow. | |
More about: The piezoelectric effect |
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| The piezoelectric effect allows a material to generate an electrical voltage when it is exposed to pressure or stretching. Piezoelectricity is a result of a displacement of the charge distribution in the material due to deformation, and can be found in biological materials such as bone, protein and DNA and also in other types of materials such as ceramics, plastics and textiles. |
| Source: Chalmers University of Technology |
