Extreme Energy Absorption in Glassy Polymer Thin Films by Supersonic Micro-projectile Impact

The nature of polymer deformation depends on the ability of the chain segments to respond to the applied load at the imposed loading rate. When the polymer response time is significantly longer than the loading duration, the polymer responds in a brittle manner. Polystyrene, for example, is a brittle, glassy solid at room temperature and absorbs very little energy during deformation. Here we show unexpected, thickness and strain-rate-dependent deformation processes in thin polystyrene films at extreme axisymmetric tensile deformation rates. The impact of a supersonic micro-projectile initiates crazing, yielding, and adiabatic heating leading to extensive plastic flow of a load-bearing viscoelastic melt prior to perforation and film rupture. The less entangled, more mobile near-surface regions of these freestanding films favorably modify these processes, increasing the specific energy absorption as thickness decreases at the highest impact velocity. This results in unprecedented energy absorption at extreme strain rates in what is normally considered a brittle material.     

Density change upon crystallization of amorphous Zr–Cu–Al thin films

Systematic deflection measurements with micro-cantilevers and a combinatorial-deposition method have been used to investigate the density change upon crystallization of amorphous Zr–Cu–Al thin films. It is found that, in general, the density change decreases from Cu-/Al-rich compositions to Zr-rich compositions, and the previously reported good glass-forming compositions are found to correspond to global minima of the density change inside respective local eutectic systems. Furthermore, we propose that the general trend of density change as a function of alloy compositions discovered in this work may have implications for the macroscopic plasticity of metallic glasses.     

Analysis of electromagnetic scattering by periodic strip grating ona grounded dielectric/magnetic slab for arbitrary plane wave incidencecase

A new type of integral equation that is coupled with strip-electric and slot-magnetic currents is applied to the analysis of electromagnetic scattering by a periodic strip grating on a grounded dielectric/magnetic slab for an oblique incident plane wave with arbitrary polarization. In the analysis, the electric and magnetic currents are expanded into a product of a series of cosine functions and a function satisfying the edge condition. Coupled linear equations for the unknown electric and magnetic currents are obtained. From the coupled linear equations, explicit expressions for the reflection coefficients are derived by the use of a single edge-mode expansion. The validity of the method is examined by numerically calculated boundary conditions. A comparison between the calculated results from the present method and a previous method by measured ones shows that the accuracy of the method is excellent. Numerical calculations show that the method converges very rapidly with reasonable accuracy     

Effect of the compression ratio on wear properties of slightly cross-linked ultra-high molecular weight polyethylene, crystallized under uniaxial compression

To improve wear properties of artificial joints, cross-linked ultra-high molecular weight polyethylene (UHMWPE) was crystallized under compression in a molten state. Slight cross-linking was created by γ-ray irradiation at a 0.5 Mrad dose under reduced pressure at room temperature before the compression. Next, the UHMWPE was melted at 200°C and compressed using two metal plates. The compression ratio (CR) is defined as the ratio of the final thickness to the original thickness of the sample. The molecular chain of the UHMWPE was orientated to the direction of deformation and was crystallized by cooling to room temperature while maintaining the deformation. The (2 0 0) crystalline plane was only orientated parallel to the compression plane in the CR=2 sample; however, in the case of the CR=5 sample, both the (2 0 0) and the (1 1 0) crystalline planes were orientated parallel to the compressed surface. The density and melting point of the sample depended on the compression ratio. The physical and the mechanical properties were increased in accordance with their compression ratio. The _c-peak of the loss modulus was shifted to a higher temperature compared with the non-compressed sample. Dimensional stability of the compressed sample by heating near 135°C was not found. It was confirmed that the wear factor also depended on the compression ratio based on the findings of pin-on-disc and pin-on-flat wear tests. The wear factor of the (CR=2) sample was similar to the non-compressed sample (CR=1); in contrast, that of the CR=5 sample was significantly smaller.     

Hepatoprotective effect of meal replacement seeds juice based on sweet potato (MRSJ) against CCl4-induced cytotoxicity in HepG2 cells

Food Science and Biotechnology - A sweet potato-based Meal Replacement Seeds Juice (MRSJ) was developed by mixing sweet potatoes and carrots with four types of seeds. Consuming the MRSJ rather than...     

Direct conversion of β-Ga2O3 thin films to β-Ga2O3 nanowires by annealing in a hydrogen atmosphere

We report the annealing process of Au/β-Ga₂O₃ thin films in a hydrogen atmosphere leading to a direct conversion of β-Ga₂O₃ thin films to β-Ga₂O₃ nanowires (NWs). Annealing in a hydrogen atmosphere results in the evaporation of β-Ga₂O₃ thin films, which are subsequently converted to β-Ga₂O₃ NWs through the vapor-liquid-solid (VLS) process assisted by Au nanocrystals. The VLS growth starts at 600?°C and progresses with increase in the annealing temperature to 800?°C. β-Ga₂O₃ NWs are formed on the surface of the host β-Ga₂O₃ thin films, resulting in the formation of a homogeneous β-Ga₂O₃ NW/β-Ga₂O₃ thin film structure. Based on structural analyses using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, a possible mechanism for the growth of β-Ga₂O₃ NWs is presented.     

BrLETM2 Protein Modulates Anthocyanin Accumulation by Promoting ROS Production in Turnip (Brassica rapa subsp. rapa)

In ‘Tsuda’ turnip, the swollen root peel accumulates anthocyanin pigments in a light-dependent manner, but the mechanism is unclear. Here, mutant g120w which accumulated extremely low levels of anthocyanin after light exposure was identified. Segregation analysis showed that the anthocyanin-deficient phenotype was controlled by a single recessive gene. By using bulked-segregant analysis sequencing and CAPS marker-based genetic mapping analyses, a 21.6-kb region on chromosome A07 was mapped, in which a calcium-binding EF hand family protein named BrLETM2 was identified as the causal gene. RNA sequencing analysis showed that differentially expressed genes (DEGs) between wild type and g120w in light-exposed swollen root peels were enriched in anthocyanin biosynthetic process and reactive oxygen species (ROS) biosynthetic process GO term. Furthermore, nitroblue tetrazolium (NBT) staining showed that the ROS level decreased in g120w mutant. Anthocyanins induced by UV-A were abolished by the pre-treatment of seedlings with DPI (an inhibitor of nicotinamide adenine nucleoside phosphorylase (NADPH) oxidase) and decreased in g120w mutant. These results indicate that BrLETM2 modulates ROS signaling to promote anthocyanin accumulation in turnip under UV-A and provides new insight into the mechanism of how ROS and light regulate anthocyanin production.     

Mixed seeds juice with high antioxidant capacity and digestive enzyme activity and its application

Food Science and Biotechnology - To investigate the synergistic and combined effects of a seed–vegetable combination, oilseed crops (safflower seed, evening primrose seed, and sesame seed)...