Lună: martie 2017

Produse Condor în aer liber cu maneci scurte cu maneci de luptă, manșon braț și pantaloni tactici operatori: noua îmbrăcăminte de luptă / tactică 2017 în curând!(Condor Outdoor Products Short-Sleeve Combat Shirt, Arm Sleeve, and Tactical Operator Pants:New 2017 Combat/Tactical Clothing Soon!)

Produse Condor în aer liber cu maneci scurte cu maneci de luptă, manșon braț și pantaloni tactici operatori: noua îmbrăcăminte de luptă / tactică 2017 în curând!tampoane pentru genunchi de injectare, împreună cu curele de prindere din velcro

Condor Outdoor

Chaos care vă va menține cald: Cercetătorii îmbunătățesc izolația termică folosind haos deliberat(Chaos that will keep you warm: Researchers improve heat insulation using deliberate chaos)

Cercetătorii de la Bayreuth au descoperit acum că materialele pot fi produse din astfel de nanoparticule care prezintă o conductivitate termică chiar mai scăzută. Aceste materiale sunt amestecuri în formă de pulbere: ordinea cristalină este astfel înlocuită cu haos, iar interpelarea plăcută a culorilor încetează. În timp ce fiecare particulă din interiorul cristalelor fotonice este înconjurată de exact douăsprezece particule în vecinătatea directă, numărul particulelor învecinate direct în amestec este inconsecvent pe tot parcursul procesului.

Posted: Mar 30, 2018

Chaos that will keep you warm: Researchers improve heat insulation using deliberate chaos

(Nanowerk News) Powder is extremely well-suited for thermal insulation when there is a jumble of different sized nanoparticles in it. This was discovered by a research group at the University of Bayreuth led by Prof. Dr. Markus Retsch. The scientists were able to determine how the thermal conductivity of powder is influenced by order and chaos in its constituent parts. They have published their findings in the journal Advanced Materials („Low Thermal Conductivity through Dense Particle Packings with Optimum Disorder”).
The starting point of the research was phototonic crystals that occur naturally in various species of insects. For example, they are responsible for the colourful, glittering appearance of butterflies’ wings. Such crystals are easy to replicate in the laboratory using polymer nanoparticles. They possess a fine, regular, and stable structure. The effect of this well-ordered structure is that it becomes difficult for heat to flow through the crystals. Thermal conductivity is low.
Computer simulations of heat dissipation
Computer simulations of heat dissipation. Left: the heat can easily permeate the ordered structure. Right: chaotic particle packings restrict the dissipation of heat. The flow of heat is the least in the dark blue areas and is highest in the red areas. (Image: Markus Retsch) (click on image to enlarge)
The researchers in Bayreuth have now found out that materials can be produced from such nanoparticles which exhibit a thermal conductivity that is even much lower. These materials are mixtures in powder form: crystalline order is thus replaced with chaos, and the pleasant interplay of colours also ceases. While each particle in the interior of photonic crystals is surrounded by exactly twelve particles in the direct vicinity, the number of directly neighbouring particles in the mixture is inconsistent throughout.
Consequently, heat must take circuitous routes, making it all the more difficult to permeate the mixture. Flowing from the warm side to the cold side in a chaotic structure is not as easy for the heat as it is in well-ordered crystals.
To completely clarify these relationships, Prof. Dr. Markus Retsch and his team used a combination of laboratory experiments and computer simulations. This allowed them to examine in detail how the composition of the particle mixture affects the flow of heat. The highest insulation effect is reached by mixing a very large number of small particles with fewer large particles. In addition to the mixing ratio, the difference in size between the two types of particles also plays a crucial role.
“Making reproducible chaos and describing it via simulations is not as easy as it sounds,” explained Prof. Retsch about the challenges of this study. “It was only possible to compare our experimental results with computer simulations because we mixed nanoparticles whose behaviour we can control very well,” he said.
In this way, the researchers at the University of Bayreuth were able to gain detailed insights into heat distribution in disordered materials. These findings are highly relevant to many applications, especially in the field of thermal insulation.
For example, they can help to improve the thermal insulation performance of bulk powders. However, they also provide valuable clues for technical applications which, conversely, rely on quick and highly controllable heat dissipation. This is the case, for instance, in the optimization of industrial sintering processes in which tiny particles of powder are melted.
The key is to precisely regulate the temperature at the melting points, which is possible thanks to improved dissipation.
Source: University of Bayreuth

„Lab-on-a-glove” ar putea determina detectarea agentului nervos la vârful degetelor purtătorului(‘Lab-on-a-glove’ could bring nerve-agent detection to a wearer’s fingertips)

Există un motiv pentru care fermele folosesc echipamente de protecție atunci când aplică pesticide organofosfatice.Agenții organofosfați nervoși, inclusiv sarin și VX, sunt foarte toxici și pot preveni funcționarea corectă a sistemului nervos.

Lab-on

Straturile electronice noi acoperite cu grafen detectează gaze nocive(New graphene-coated e-fabrics detect noxious gases)

Straturile electronice noi acoperite cu grafenie detectează gaze nocive
Materialele acoperite cu oxid de grafen redus s-au dovedit a fi deosebit de sensibile la detectarea dioxidului de azot

Detector de gaze

Dispozitivul de monitorizare cu cost redus utilizează lumină pentru a detecta rapid scurgerile de petrol(Low-cost monitoring device uses light to quickly detect oil spills)

Cercetătorii au dezvoltat un dispozitiv simplu care poate detecta o deversare de ulei în apă și apoi identifică tipul de ulei prezent pe suprafață

Low-cost