Does the Addition of Cellulosic Micro/nanofibrils Improve the Properties of Hydroxypropyl Methylcellulose Films?

Damages to ecosystems, due to the consumption of petroleum-based materials, can be mitigated with the use of biopolymers such as cellulose derivatives. The objective was to evaluate the influence of different proportions of cellulose micro/nanofibrils (MFC/NFC) on the properties of hydroxypropyl methyl cellulose (HPMC) films. Films were prepared using proportions of 0, 25, 50, 75 and 100% (w/w) of MFC/NFC of Pinus sp. in relation to HPMC. The physical, barrier, surface, optical, morphological and mechanical properties were evaluated. Data were analyzed with descriptive statistics, linear regression, principal component analysis and Pearson correlation. Solids content, basis weight and density values increased with higher MFC/NFC amount, while thickness and porosity were reduced. SEM images showed that films with more than 50% MFC/NFC had a more granular surface resulting in reduction of transparency from 80 to 65%. The water vapor penetration did not differ between films and the degradation in water was reduced from 40 to 5% as MFC/NFC was added. There were no differences for contact angle and wettability, but all films showed high resistance to fat penetration. Films with MFC/NFC contents between 75 and 100% showed higher values for tensile strength (50 to 65 MPa) and Young's modulus (6 to 10 MPa) and lower elongation at break (1 to 2%). The experimental results indicated that films with MFC/NFC contents above 50% have potential to be used as packaging material.

Pulse load on a stationary barrier during an explosion in water

С использованием экспериментальных данных о взрывах в воде найдена аналитическая зависимость распределения удельного импульса взрывной нагрузки по длине балки. Учтены эффекты отражения возмущенного потока воды от поверхности преграды, глубина ее расположения в водоёме, взаимное расположение сферического заряда ВВ и преграды в воде, физические характеристики заряда. Using experimental data on explosions in water, an analytical dependence of the distribution of the specific impulse of the explosive load along the length of the beam is found. The effects of reflection of the disturbed water flow from the barrier surface, the depth of its location in the reservoir, the mutual location of the spherical explosive charge and the barrier in the water, the physical characteristics of the charge are taken into account.

STUDY OF STEEL BARRIER SURFACE AFTER HIGH-SPEED EXPOSURE OF W AND TIC POWDERS

The surface layer of an obstacle made of U8 steel is investigated after high-speed exposure to a flow of powder particles. After analyzing the frames of high-speed photography, the average velocities of movement of particles of tungsten and titanium carbide powders were determined. It is shown that the shock-wave loading of the barrier material and the effect of particles accelerated by the explosion energy provide a change in the physical and mechanical properties of the surface and the volume of the steel barrier material.

An Improved P-Type Doped Barrier Surface AlGaN/GaN High Electron Mobility Transistor with High Power-Added Efficiency

An improved P-type doped barrier surface AlGaN/GaN high electron mobility transistor with high power-added efficiency (PDBS-HEMT) is proposed in this paper. Through the modelling and simulation of ISE-TCAD and ADS software, the influence of the P-type doped region on the performance parameters is studied, and the power-added efficiency (PAE) obtained and effectively improved is further verified. The drain saturation current and the threshold voltage of PDBS-HEMT has no major change compared with the traditional structure; the peak transconductance decreases slightly, but the breakdown voltage is significantly enhanced. Furthermore, the gate-source capacitance and gate-drain capacitance are reduced by 14.6% and 14.3%, respectively. By simulating the RF output characteristics of the device, the maximum oscillation frequency of the proposed structure is increased from 57 GHz to 63 GHz, and the saturated output power density is 10.9 W/mm, 9.3 W/mm and 6.4 W/mm at the frequency of 600 MHz, 1200 MHz and 2400 MHz, respectively. The highest PAE of 88.4% was obtained at 1200 MHz. The results show that the PDBS structure has an excellent power and efficiency output capability. Through the design of the P-type doped region, the DC and RF parameters and efficiency of the device are balanced, demonstrating the great potential of PDBS structure in high energy efficiency applications.

DEVELOPMENT OF A PROGRAM FOR CALCULATING THE CONCENTRATION FIELD OF THE DISTRIBUTION OF SULFUR DIOXIDE IN THE AIR

A program for calculating the concentration field of the distribution of sulfur dioxide in the air from a point source of emission using a kinetic model, taking into account the barrier surface of green spaces, is considered.

Effect of Surface Variations on Resistive Switching

In this chapter, we study factors that dominate the interfacial resistive switching (RS) in memristive devices. We have also given the basic understanding of different type of RS devices which are predominantly interfacial in nature. In case of resistive random access memory (RRAM), the effect of surface properties on the bulk cannot be neglected as thickness of the film is generally below 100 nm. Surface properties are effected by redox reactions, interfacial layer formation, and presence of tunneling barrier. Surface morphology affects the band structure in the vicinity of interface, which in turn effects the movements of charge carriers. The effect of grain boundaries (GBs) and grain surfaces (GSs) on RS have also been discussed. The concentration of vacancies (Ov)/traps/defects is comparatively higher at GBs which leads to leakage current flow through the GBs predominantly. Such huge presence of charge carriers causes current flow through grain boundaries.

Mobile anti-vehicle barrier made of high-performance fibre-reinforced concrete

The article presents a mobile anti-vehicle barrier created from a high-performance fibre-reinforced concrete, which resembles a historical design of the Czech Hedgehog barrier. The performance of this design when subjected to a moderate velocity vehicle impact was evaluated. A preliminary crash test provided basic data to perform an optimisation of the design using numerical simulations conducted in LS-DYNA. Several key observations were made regarding the crucial role of the barrier-surface interactions and overall barrier behaviour. Based on the simulations, improved geometry of the barrier was proposed and subjected to more full-scale crash tests with various barrier placements. The improved barrier design was able to stop an ordinary road vehicle weighing 1300 kg moving with a velocity of 48 km/h while retaining beneficial characteristics, most importantly low weight.

T cell engagement of cross-presenting microglia protects the brain from a nasal virus infection

The neuroepithelium is a nasal barrier surface populated by olfactory sensory neurons that detect odorants in the airway and convey this information directly to the brain via axon fibers. This barrier surface is especially vulnerable to infection, yet respiratory infections rarely cause fatal encephalitis, suggesting a highly evolved immunological defense. Here, using a mouse model, we sought to understand the mechanism by which innate and adaptive immune cells thwart neuroinvasion by vesicular stomatitis virus (VSV), a potentially lethal virus that uses olfactory sensory neurons to enter the brain after nasal infection. Fate-mapping studies demonstrated that infected central nervous system (CNS) neurons were cleared noncytolytically, yet specific deletion of major histocompatibility complex class I (MHC I) from these neurons unexpectedly had no effect on viral control. Intravital imaging studies of calcium signaling in virus-specific CD8+ T cells revealed instead that brain-resident microglia were the relevant source of viral peptide–MHC I complexes. Microglia were not infected by the virus but were found to cross-present antigen after acquisition from adjacent neurons. Microglia depletion interfered with T cell calcium signaling and antiviral control in the brain after nasal infection. Collectively, these data demonstrate that microglia provide a front-line defense against a neuroinvasive nasal infection by cross-presenting antigen to antiviral T cells that noncytolytically cleanse neurons. Disruptions in this innate defense likely render the brain susceptible to neurotropic viruses like VSV that attempt to enter the CNS via the nose.