The response to stress involves the activation of pathways leading either to protection from the stress origin, eventually resulting in development of stress resistance, or activation of the rapid ...death of the organism. Here we hypothesize that mitochondrial reactive oxygen species (mtROS) play a key role in stress-induced programmed death of the organism, which we called "phenoptosis" in 1997. We demonstrate that the synthetic mitochondria-targeted antioxidant SkQ1 (which specifically abolishes mtROS) prevents rapid death of mice caused by four mechanistically very different shocks: (a) bacterial lipopolysaccharide (LPS) shock, (b) shock in response to intravenous mitochondrial injection, (c) cold shock, and (d) toxic shock caused by the penetrating cation C
TPP. Importantly, under all these stresses mortality was associated with a strong elevation of the levels of pro-inflammatory cytokines and administration of SkQ1 was able to switch off the cytokine storms. Since the main effect of SkQ1 is the neutralization of mtROS, this study provides evidence for the role of mtROS in the activation of innate immune responses mediating stress-induced death of the organism. We propose that SkQ1 may be used clinically to support patients in critical conditions, such as septic shock, extensive trauma, cooling, and severe infection by bacteria or viruses.
The microwave response of a two-dimensional electron system (2DES) covered by a conducting top gate is investigated in the relativistic regime for which the 2D conductivity σ_{2D}>c/2π. Weakly damped ...plasma waves are excited in the gated region of the 2DES. The frequency and amplitude of the resulting plasma excitations show a very unusual dependence on the magnetic field, conductivity, gate geometry, and separation from the 2DES. We show that such relativistic plasmons survive for temperatures up to 300 K, allowing for new room-temperature microwave and terahertz applications.
Photovoltaic solar-energy conversion is one of the most promising technologies for generating renewable energy, and conversion of concentrated sunlight can lead to reduced cost for solar electricity. ...The book is written for scientists.
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The paper proposes a novel technique of time depend dielectric breakdown for the wafer-level testing of thin dielectric of MIS devices based on concatenation of J-Ramp and Bounded J-Ramp methods. ...The suggested method enhances the existing method capabilities by introducing measurement injection modes. When DUT is under the measurement mode, the charge injection into the gate dielectric is realized under constant current density
J
m
at which any significant charge degradation of dielectric is not observed. Introduction of the measurement modes give an opportunity to monitor a change of the charge state of thin gate dielectric during all the test. The suggested test is started similar to Bounded J-Ramp method and then in order to raise the monitoring speed, the value of bounded current
J
b
could be step wisely increased over certain time intervals which are much longer in time in comparison with J-Ramp method. As a result, the charge injection into the gate dielectric could be implemented under multiple
J
b
values. This test algorithm gives an opportunity to greatly enhance functional capabilities of the existing test methods and the suggested technique raises speed to test.
The paper proposes an experimental approach to determine the external quantum efficiency of multijunction solar cells with pronounced optical coupling. A new technique based on the cascade mechanism ...of coupling has been elaborated to separate the influence of the induced luminescent flux from the external illumination and to establish the absolute values of photosensitivity without negative impact of optical interaction between subcells. The novelty of this work lies in the method extended to multijunction devices with N-number of subcells.
•Cascade optical coupling is a feature of multi-junction solar cells.•Optical coupling negatively impacts on quantum efficiency measurements.•Method describes how to avoid influence of optical coupling on experimental data.
Photovoltaic laser-power converters for a wavelength of λ = 809 nm are developed and fabricated on the basis of single-junction AlGaAs/GaAs structures grown by metal-organic vapor-phase epitaxy. The ...parameters of the photovoltaic structure constituted by an optical “window” and a cladding layer are optimized by mathematical simulation. Photovoltaic converters with areas of
S
= 10.2 and 12.2 mm
2
and 4 cm
2
are fabricated and studied. For photocells with S = 10.2 mm
2
, the monochromatic efficiency (η) was 60% at a current density of 5.9 A/cm
2
. A photovoltaic module with a working voltage of 4 V (η = 56.3% at 0.34 A/cm
2
) is assembled.
Resonant microwave absorption by two-dimensional electron systems based on GaAs/AlGaAs heterostructures with a metallic back gate is investigated. The regime where the velocity of a screened plasma ...wave in a two-dimensional system calculated in the quasi-static approximation exceeds the speed of light in the substrate is obtained. It is established that relativistic retardation-related effects in this situation lead to significant changes in the dispersion and magnetic-field behavior of screened two-dimensional plasmons. It is found that the retardation effects result in the pronounced renormalization of the cyclotron and plasma frequencies. There is good agreement between the experimental results and the existing theory.
We report the results of experimental and numerical investigations of a discharge KrF laser with specific pump power of 3.5 and 7 MW/cm
3
; generation is obtained with specific radiation pulse energy ...of about 6 and 9.5 J/L for an internal energy efficiency of about 4%. Time dependences of the formation of charged and excited particles in a dense excimer plasma with an electron concentration of ~10
16
cm
–3
are obtained. The conditions for effective operation of the laser are proposed, which will ensure a further increase in the specific radiation energy by more than two times with preserved high internal laser efficiency relative to the energy input into the discharge.
The influence of a degree of strain by rotary forging, as well as post-deformation annealing on the structure and mechanical properties of a clad aluminum alloy/copper bimetallic material was ...studied. Rotary forging of the initial bimetallic billet was carried out step by step from a diameter of 20.1 mm to a diameter of 2.4 mm. Rotary forging of the aluminum alloy/copper bimetallic material to a diameter of 5.3 mm leads to the formation of a mixed fine-grained and nanocrystalline oriented structure in an aluminum shell and to a decrease in the average grain size by 4.5 times and to an increase in the density of crystalline defects in a copper core. A reduction in the aluminum alloy/copper bimetallic material diameter to 2.4 mm (with intermediate annealing) leads to the formation of a fine-grained elongated grain-subgrain oriented structure in the aluminum shell and to the formation of a mixed cellular and subgrain structure in a copper core. Rotary forging leads to a significant increase in the strength of the aluminum alloy/copper bimetallic material and to a decrease in ductility. The optimal combination of increased strength and satisfactory ductility provides post-deformation annealing.
Graphic Abstract
The effect of equal-channel angular pressing on structural phase transformations and mechanical properties of the as-cast hypoeutectic Al–4Ca–1.3Fe–0.8Mn–0.1Zr–0.1Sc alloy has been studied. ECAP was ...carried out under isothermal conditions at a temperature of 200 °C, with a channel intersection angle of 110º, using the BC route and the number of passes N = 6. After ECAP, a substructure with an increased dislocation density has developed in the alloy. ECAP led, firstly, to the evolution of the dendritic structure (dendrites elongate and merge with each other), and secondly, to the refinement of the Al4Ca, Al4Ca(Fe) and Al3−x(Fe, Mn) eutectic phase particles to nano- and submicron scale, their mixing and partial segregation of calcium. The tensile tests of the ECAP processed alloy showed that its strength increased, while its ductility decreased. The yield point increased from 122 to 257 MPa, the ultimate tensile strength increased from 174 to 281–314 MPa, and the relative elongation decreased from 6 to 1–3%. After ECAP, the strength is higher, and the relative elongation is lower for longitudinal specimens compared to transverse specimens.
•The as-cast Al-4Ca-1.3Fe-0.8Mn-0.1Zr-0.1Sc hypoeutectic alloy was processed by ECAP at 200 °C.•The elongation of the (Al)-dendrites along the pressing direction and their merging occurs.•The refinement of the eutectic phase particles to nano- and submicron scale occurs.•The eutectic phase particles mixing and partial Ca segregation occurs as a result of mass transfer.•The 1.7–2.2-fold increase in the alloy’s strength while maintaining moderate ductility occurs.
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