Improved passivation depth of porous fluorescent 6H-SiC with Si/C faces using atomic layer deposition

We investigated the effects of different growth facets of 6H-SiC and different voltage waveforms on the porous structure and luminescence properties. The structure formed on the surface after anodic etching significantly changed because of the difference in the growth plane, whereas dendritic and columnar pores were observed inside the Si- and C-face samples. These large porous structures were shown to promote the penetration depth of the atomic-layer-deposited Al2O3 films, and a recorded passivation depth of 30-µm layer was confirmed in C-face porous SiC. From the results using fluorescence microscope and PL spectra measurement, it was concluded that the pulsed-voltage etching was preferable for fabricating uniform porous structures compared with the constant-voltage etching. However, the enhancement of the luminescence intensity needs to be further improved to realize high luminescent efficiency in porous fluorescent SiC.

Effect of Maternal Betaine Supplementation on Growth, Plane of Nutrition, Blood Biochemical Profile and Antioxidant Status of Progeny Pigs

Background: Dietary supplementation of methyl donors like vitamins B9, B12, choline and betaine have been reported to reduce oxidative stress not only in sows but can also reduce oxidative stress in offspring through epigenetic modulation of DNA. However, cell proliferation and fetal development and oxidative stress associated with it is not uniform during the whole length of gestation. Hence this experiment was conducted to study the effects of maternal betaine supplementation on growth, plane of nutrition and antioxidant profile of progeny pigs.Methods: Eighteen crossbred (Landrace X Desi) sows were randomly distributed into three groups of six each in an experiment based on completely randomized design (CRD). The sows in control (T0) were fed standard ration to meet their requirements. Supplementary betaine at 3 g/kg DM were provided either during late pregnancy (d 76 onwards till parturition) only or throughout the length of gestation to the sows of groups T1 and T2, respectively. The samples of feed offered, residue and faeces were analyzed for proximate principles following the standard procedures. Blood samples from the progeny piglets were collected and antioxidant status of the piglets assessed by the measurement of superoxide dismutase (SOD) and catalase (CAT) by using standard kits.Result: The serum concentration of SOD was comparable (p greater than 0.05) among the groups, whereas serum concentration of catalase was higher (p less than 0.05) in piglets born to the dam exposed to supplementary beanie during gestation, the best response was observed whilst betaine was supplemented in the maternal diets during the whole length of gestation It was concluded that supplementation of betaine at 3g/kg in the diet of pregnant sows improved the antioxidant capacity of piglets borne to them.

Релаксация напряжений несоответствия в гетероструктурах alpha-Ga-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-/alpha-Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- при образовании дислокаций несоответствия

We propose the analytical models describing misfit stress relaxation in α-Ga2O3/α-Al2O3 film/substrate heterostructures taking into account the crystal lattices anisotropy of the heterostructure materials. We consider the nucleation of misfit dislocations as a result of basal or prismatic slip in α-Ga2O3/α-Al2O3 heterostructures with various film orientations. We calculate and analyze the dependences of the critical thickness hc (film thickness above which the nucleation of misfit dislocations is favorable) on the angle ϑ between the polar c-axis and the normal to the film growth plane for α-Ga2O3/α-Al2O3 heterostructures. We demonstrate that accounting for elastic constant C14 is not critical in the considered relaxation models for the α Ga2O3/α Al2O3 heterostructures.

Two-dimensional inorganic molecular crystals

Two-dimensional molecular crystals, consisting of zero-dimensional molecules, are very appealing due to their novel physical properties. However, they are mostly limited to organic molecules. The synthesis of inorganic version of two-dimensional molecular crystals is still a challenge due to the difficulties in controlling the crystal phase and growth plane. Here, we design a passivator-assisted vapor deposition method for the growth of two-dimensional Sb2O3 inorganic molecular crystals as thin as monolayer. The passivator can prevent the heterophase nucleation and suppress the growth of low-energy planes, and enable the molecule-by-molecule lateral growth along high-energy planes. Using Raman spectroscopy and in situ transmission electron microscopy, we show that the insulating α-phase of Sb2O3 flakes can be transformed into semiconducting β-phase under heat and electron-beam irradiation. Our findings can be extended to the controlled growth of other two-dimensional inorganic molecular crystals and open up opportunities for potential molecular electronic devices.

Apatite with lamellae of sulfide and other phases in ultrahigh-pressure eclogites from Nové Dvory, Moldanubian Zone, Czech Republic

Exsolution lamellae of baryte, Fe sulfides, Cu sulfides and Fe oxides were observed in apatite enclosed in garnet and omphacite and their intergranular spaces in ultrahigh-pressure eclogite in the Moldanubian Zone, Czech Republic. Micro-textural relations and compositional mapping of the apatite indicates a close relationship between the density of the exsolution lamellae and compositional domains that are rich in sulfur and iron. No relation between compositional domains and fluorine or chlorine content or any evidence of apatite metasomatisation was observed. On the basis of cathodoluminescence images, the compositional domains reflect sector zoning in apatite crystals by preferential uptake of elements due to differences in surface charge and morphology on the growth plane. It is concluded that the lamellae are products of exsolution in a closed system resulting from temperature decrease during metamorphism.

Fracture Toughness Behaviour of 316L Stainless Steel Samples Manufactured Through Selective Laser Melting

Selective laser melting (SLM) is a relatively new manufacturing technique which offers many benefits. However the utilisation of SLM manufactured components depends on the assurance of their integrity during operation. Fracture toughness testing (JIC) has been performed on as-built compact tension fracture mechanics samples manufactured in three orthogonal directions. When the crack growth plane was transverse to the interface of the build layers, the fracture toughness values were found to be similar to those manufactured using conventional techniques. However, the fracture toughness is significantly reduced when the crack plane is parallel to the interface of the build layers. Simple heat treatments have been performed on Charpy fracture samples and the resulting impact energy values indicate that the fracture toughness of a component may be improved by heat treatment.

Fabrication of SiC Composites with Synergistic Toughening of Carbon Whisker andIn Situ3C-SiC Nanowire

The SiC composites with synergistic toughening of carbon whisker andin situ3C-SiC nanowire have been fabricated by hot press sinter technology and annealed treatment technology. Effect of annealed time on the morphology of SiC nanowires and mechanical properties of theCw/SiC composites was surveyed in detail. The appropriate annealed time improved mechanical properties of theCw/SiC composites. The synergistic effect of carbon whisker and SiC nanowire can improve the fracture toughness forCw/SiC composites. The vapor-liquid-solid growth (VLS) mechanism was proposed. TEM photo showed that 3C-SiC nanowire can be obtained with preferential growth plane ({111}), which corresponded to interplanar spacing about 0.25 nm.