Effect of Supersonic Fine Particles Bombarding on the Service Life of Thermal Barrier Coating

Thermally Grown Oxide（TGO） is a dominating component in controlling the effectiveness of thermal barrier coating.During the growth of TGO,whether we could homogeneously distribute Al atom on the TGO and the intermediate metal layer will be the key factor in forming TGO with continuous,uniform and single-ingredient（Al2O3）.In this experiment,we bombarded particles on to the metallic bound layer.We studied the influence of supersonic particle bombardment on the diffusion of Al.We hope to control the growth of TGO by monitoring the diffusion of Al.Thermal barrier coating（TBC）,which consists of a NiCoCrAlY bond coat and a ZrO2-8Y2O3（wt.%） topcoat（TC）,is fabricated on the nickel-base superalloy by air plasma spray（APS）.NiCoCrAlY bond coat is treated by supersonic fine particles bombarding（SFPB）.The morphology,oxidation behavior of TBC and phase are characterized by scanning electron microscope（SEM） equipped with an energy dispersive spectromrter（EDS） and X-ray diffractometer（XRD）.The influence of supersonic fine particles bombarding technique on the service life of thermal barrier coating is studied.The results show that SFPB technique improves the flaw of excessive surface undulation in the as-sprayed bond coat.A continuous,uniform and single-ingredient（Al2O3） TGO can quickly form in the SFPB TBC during high temperature oxidation process.The thickening of TGO is relatively slow.These will effectively suppress the formation of other non-protective oxides.Therefore,SFPB technique reduces the growth stress level generated by the continuous growth of TGO,and also avoids the stress concentration induced by formation of the large particle spinal oxide.Thermal barrier coating still remains well after 350 thermal cycles.The service life of TBC is improved.The proposed research provides theoretical basis and technical references to further improve and enhance the SFPB technique.

Structure and Strain Properties of GaN Films Grown on Si（111） Substrates with AlxGa1-xN/AlyGa1-yN Superlattices

CaN films with an AlxGa1-xN/AlyGa1-xN superlattice （SL） buffer layer are grown on Si（111） substrates by metal-organic chemical vapor deposition （MOCVD）. The structure and strain properties of the samples are studied by optical microscopy, Raman spectroscopy, x-ray diffractometry and atomic force microscopy. The results show that the strain status and crystalline quality of the CaN layers are strongly dependent on the difference of the Al composition between AlxCa1-xN barriers and AlyCa1-yN wells in the SLs. With a large Al composition difference, the CaN film tends to generate cracks on the surface due to the severe relaxation of the SLs. Otherwise, when using a small Al composition difference, the crystalline quality of the CaN layer degrades due to the poor function of the SLs in filtering dislocations. Under an optimized condition that the Al composition difference equals 0.1, the crack-free and compressive strained CaN film with an improved crystalline quality is achieved. Therefore, the AlxGa1-xN/AlyGal-yN SL buffer layer is a promising buffer structure for growing thick CaN films on Si substrates without crack generation.

GaN As/InGaAs Superlattice Solar Cells with High N Content in the Barrier Grown by All Solid-State Molecular Beam Epitaxy

We demonstrate nearly i e V GaN0.03As0.97 /In0.09 Ga0.91As strain-compensated short-period superlattice solar cells by all solid-state molecular beam epitaxy. The optimal period thickness for the superlattice growth is achieved to realize high structural quality. Meanwhile, the annealing conditions are optimized to realize a pho- toluminescence （PL） at a low temperature. However, no PL signal is detected at room temperature, which could be reflected by a lower open-circuit voltage of the fabricated devices. The GaN0.03As0.97/In0.09Ga0.91As super- lattice solar cells show a reasonably-high short-circuit current density （Jsc） of over lOmA/cm2. Eurthermore, a concentration behavior is measured, which shows a linear relationship between Jsc and concentration ratios. The extrapolated ideality factor and saturated current density by the concentration action are in good agreement with that extracted by the dark case of the p-i-n diodes.

Antihyperglycemic and antioxidant effects of Solanum xanthocarpum leaves(field grown & in vitro raised) extracts on alloxan induced diabetic rats

Objective:To investigate antidiabetic efficacy of the extract of field grown and in vitro raised leaves of Solanum xanthocarpum(S.xanthocarpum) against alloxan induced diabetic rats. Methods:The antidiabetic activity of the crude methanol extracts of the field grown and in vitro raised leaves of S.xanthocarpum at different concentrations(100-200 mg/kg bw) was tested against alloxan induced diabetic rats.The antidiabetic efficacy was validated through various biochemical parameters and the antioxidant effect was also determined.The phytochemical analyses of field grown S.xanthocarpum and in vitro rasied 5.xanthocarpum leaves were done by estimating their chlorophyll,carotenoids,total sugar,protein,amino acid and minerals contents. Results:The results revealed that the methanol extracts of both the leaves(field grown and in vitro raised) of S.xanthocarpum was efficient anti hyperglycemic agents at a concentration of 200 mg/kg bw and posses potent antioxidant activity.However,the extracts of in vitro rasied S.xanthocarpum raised leaves exhibit higher efficacy than the field grown leaves in all tested concentrations.Proximal composition and mineral analysis of S.xanthocarpum revealed higher concentration of contents in in vitro rasied S.xanthocarpum than field grown S.xanthocarpum. Conclusions:From the results it can be concluded that the leaves extracts of S.xanthocarpum can be a potential candidate in treating the hyperglycemic conditions and suits to be an agent to reduce oxidative stress.

Improving maize grain yield by formulating plant growth regulator strategies in North China

Plant growth regulators(PGRs) are artificially synthesized compounds that have become an important technical guarantee for agricultural production. EDAH(containing 27% ethephon and 3% DA-6) has been proven to inhibit stalk elongation, promote stalk bold and increase mechanical strength and number of vascular bundles. DA-6 could enhance plant photosynthetic capacity and promote cell division and growth. In our study, experiments were performed at summer maize growing season during 2018–2019. The result showed that plant height, ear height and center of gravity height of maize with EDAH+DA-6 treatment were decreased by 10.18, 16.77 and 13.21%, respectively;leaf area and leaf area index also significantly(P<0.001) decreased by 24.11 and 60.15%, respectively;the value of mean tilt angle significantly(P<0.001) increased by 16.72% compared with the control plants, which meant that EDAH+DA-6 could shape more compact plant type. Therefore, lodging rate of maize with EDAH+DA-6 treatment decreased by 6.95% compared with control plants, and the grain yield was increased by 15.51%. In addition, EDAH+DA-6 treatment significantly improved the quality of maize base stalks, such as improving mechanical properties, which increased maize base stalk crushing strength by 22.23%;increased the hemicellulose, cellulose and lignin contents by 6.93, 3.87 and 30.21%, respectively. In conclusion, EDAH+DA-6 treatment could improve summer maize yield by shaping plant morphological characteristics and group photosynthesis.

Electrochemically Grown Ultrathin Platinum Nanosheet Electrodes with Ultralow Loadings for Energy-Saving and Industrial-Level Hydrogen Evolution

Nanostructured catalyst-integrated electrodes with remarkably reduced catalyst loadings,high catalyst utilization and facile fabrication are urgently needed to enable cost-effective,green hydrogen production via proton exchange membrane electrolyzer cells(PEMECs).Herein,benefitting from a thin seeding layer,bottom-up grown ultrathin Pt nanosheets(Pt-NSs)were first deposited on thin Ti substrates for PEMECs via a fast,template-and surfactant-free electrochemical growth process at room temperature,showing highly uniform Pt surface coverage with ultralow loadings and vertically well-aligned nanosheet morphologies.Combined with an anode-only Nafion 117 catalyst-coated membrane(CCM),the Pt-NS electrode with an ultralow loading of 0.015 mgPt cm−2 demonstrates superior cell performance to the commercial CCM(3.0 mgPt cm^(−2)),achieving 99.5%catalyst savings and more than 237-fold higher catalyst utilization.The remarkable performance with high catalyst utilization is mainly due to the vertically well-aligned ultrathin nanosheets with good surface coverage exposing abundant active sites for the electrochemical reaction.Overall,this study not only paves a new way for optimizing the catalyst uniformity and surface coverage with ultralow loadings but also provides new insights into nanostructured electrode design and facile fabrication for highly efficient and low-cost PEMECs and other energy storage/conversion devices.

Study of Digital Management System of Milking Process on Large-Sized Dairy Farm

This study was to supply the systemic and full milking process data to support the implementation of both dairy herd improvement （DHI） and digital feeding of dairy cattle. This study designed the relational structured database and developed a set of digital management information system on milking process of intensive dairy farm using Visual Basic 6.0, Access databases, and Crystal report combining the milking characteristics of a grown cow, such as quality and sanitation testing indexes of raw milk. The system supplies a series of convenient, intelligent input interfaces of crude datum, and can count, analyze, and graphically show milking datum based on different types and different parities of cows or herds in a specific duration, and can dynamically produce some important derived data, such as days of grown cow, daily average of milk production of grown cow, days of cow milk production, and daily average of milking cow production; and can carry out all-pervasive data mining. With the help of system analysis and software design techniques, it is possible to realize precision farming for a dairy cattle herd based on whole digital management of milking process and realtime prediction on nutrient requirements and ration of dairy cattle, as well as dairy herd improvement.

Influence of Surface Structures on Quality of CdTe(100) Thin Films Grown on GaAs(100) Substrates

We report the epitaxial growth of single-crystalline Cd Te（100） thin films on Ga As（100） substrates using molecular beam epitaxy. By controlling the substrate pre-heated temperature with adjustable Te flux, three different reconstructed surfaces are realized, and their influence on the subsequent Cd Te growth is investigated. More importantly, we find that both the presence of a thin native oxide layer and the formation of Ga-As-Te bonds at the interface enable the growth along the（100） orientation and help to reduce the threading dislocations and other defects. Our results provide new opportunities for compound semiconductor heterogeneous growth via interfacial engineering.

Fracture Mechanics,Crack Propagation and Microhardness Studies on Flux Grown ErAlO_3 Single Crystals

Results on fracture mechanics and crack propagation have been obtained, making use of Vickers microhardness studies on two different crystallographic planes [(110) and (001)] of flux grown erbium aluminate crystals in the load ranging from 10-100 g. The variation of microhardness with load which is best explained by Hays and Kendall's law leads to the load independent values of hardness. Classification of cracks is dealt with and it is reported that the transition from Palmqvist to median types of cracks occurs at higher loads. The values of fracture toughness (K_C), and brittleness index (B_i) are calculated using median types of cracks.

Chemical Forms of Selenium in Corn and Rice Grown in a High Selenium Area of China

The chemical forms of selenium were determined in maize grown near Yutangba Village and in rice grown near Haubei village, Exi Prefecture, Enshi county of Hubei Province, China. The maize sample contained 18 ppm and the rice samples an average of 3.6 ppm selenium. After they were ground to obtain a fine flour, this was acid hydrolyzed with hydrochloric acid in an inert atmosphere and the hydrolyzates chromatographed on columns of Dionex DC6A resin. The results indicate that the majority of the selenium is present as selenomethionine in both rice and corn.

Growth and Solvent Effects of a Promising Nonlinear Optical Sodium Paranitrophenolate Dihydrate (NO_2-C_H_4-ONa·2H_2O) Single Crystal

Sodium paranitrophenolate dihydrate (NPNa·2H2O) is an excellent semiorganic nonlinear optical (NLO) material, crystallizes both in water and methanol with high degree of transparency. Good optical quality single crystals of dimension upto 18 mm×6 mm×3 mm are obtained by isothermal solvent evaporation technique. The solubility of the crystal in different solvents was measured gravimetrically. The single crystals of NPNa·2H2O show variation in physical properties and growth rate in different solvents. Methanol or ethanol solution yields crystals of bipyramidal shape with clear morphology. However, methanol grown crystal is exhibiting improved hardness parameters and possesses excellent thermal stability as compared to water grown crystals. The effects of solvent on hardness parameter along with thermal and optical properties of NPNa·2H2O was revealed in this paper.

Review of Numerical Simulation of TGO Growth in Thermal Barrier Coatings

Thermally grown oxide(TGO)is a critical factor for the service life of thermal barrier coatings(TBC).Numerical simulations of the growth process of TGO have become an effective means of comprehensively understanding the progressive damage of the TBC system.At present,technologies of numerical simulation to TGO growth include two categories:coupled chemical-mechanical methods and mechanical equivalent methods.The former is based on the diffusion analysis of oxidizing elements,which can describe the influence of bond coat(BC)consumption and phase transformation in the growth process of TGO on the mechanical behavior of each layer of TBC,and has high accuracy for the thickness evolution of TGO,but they cannot describe the lateral growth of TGO and the rumpling phenomenon induced.The latter focuses on describing the final stress and strain state after the growth of a specific TGO rather than the complete growth processes of TGO.Based on the measured TGO thickness growth curve,simulations of thickening and lateral growth can be achieved by directly applying anisotropic volumetric strain to oxidized elements and switching elements properties from the BC to the TGO.

Influence of Al Preflow Time on Surface Morphology and Quality of AlN and GaN on Si(111) Grown by MOCVD

We investigate the influence of A1 preflow time on surface morphology and quality of AIN and GaN. The AIN and GaN layers are grown on a Si （111） substrate by metal organic chemical vapor deposition. Scanning electron microscopy, atomic force microscopy, x-ray diffraction and optical microscopy are used for analysis. Consequently, we find significant differences in the epitaxial properties of AlN buffer and the GaN layer, which are dependent on the AI preflow time. A1 preflow layers act as nucleation sites in the case of AiN growth. Compact and uniform AIN nucleation sites are observed with optimizing A1 preflow at an early nucleation stage, which will lead to a smooth AIN surface. Trenches and AlN grain clusters appear on the AIN surface while meltoback etching occurs on the GaN surface with excessive A1 preflow. The GaN quality variation keeps a similar trend with the AIN quality, which is influenced by AI preflow. With an optimized duration orAl preflow, crystal quality and surface morphology of AIN and GaN could be improved.

Enrichment of the less polar ginsenoside (Rg3) from ginseng grown in New Zealand by post-harvest processing and extraction

Background:Previous studies showed that New Zealand-grown ginseng contains an abundance of ginsenosides and that rare less polar ginsenosides,such as Rg3,exhibit more pharmacological activities than polar ginsenosides,which are the major components of ginseng.Methods:The ginsenoside profile of New Zealand-grown Panax ginseng was manipulated by treatment with acetic acid,sodium hydroxide,pH,and high temperature.The abundance of 23 ginsenosides extracted by different treatments was quantified using high-performance liquid chromatography.Results:Treatment with 0.5 mol/L acetic acid can stimulate the degradation of polar ginsenosides to less polar ginsenosides(5.6%Rg3 was accumulated,P<0.0001).Furthermore,when ginseng root was treated at 121℃ for 100 min in a pH 3.0 acetic acid aqueous solution,the majority of the polar ginsenosides were converted into less polar ginsenosides.Specifically,83.46±3.69%(P=0.0360)of the less polar ginsenosides and 41.01±2.39%(P=0.0412)of Rg3 were enriched.In contrast,alkali treatment did not convert the polar ginsenosides into less polar ginsenosides at mild temperature and less conversion was observed compared with acid treatment at high temperature.Conclusion:This is the first attempt to manipulate the ginsenoside profile of New Zealand-grown ginseng.The conditions(high temperature with low pH)may be modified to produce and enrich the less polar ginsenoside fraction(especially Rg3)from the total ginseng extract.

Comparison of GaN/AlGaN/AlN/GaN HEMTs Grown on Sapphire with Fe-Modulation-Doped and Unintentionally Doped GaN Buffer:Material Growth and Device Fabrication

AlGaN/GaN high electron mobility transistors （HEMTs） grown on Fe-modulation-doped （MD） and unintentionally doped （UID） GaN buffer layers are investigated and compared. Highly resistive GaN buffers （10^9Ω·cm） are induced by individual mechanisms for the electron traps＇ formation： the Fe MD buffer （sample A） and the UID buffer with high density of edge-type dislocations （7.24×10^9cm^-2, sample B）. The 300K Hall test indicates that the mobility of sample A with Fe doping （2503cm^2V^-1s^-1） is much higher than sample B （1926cm^2V^-1s^-1） due to the decreased scattering effect on the two-dimensional electron gas. HEMT devices are fabricated on the two samples and pulsed I–V measurements are conducted. Device A shows better gate pinch-off characteristics and a higher threshold voltage （-2.63V） compared with device B （-3.71V）. Lower gate leakage current ｜IGS｜ of device A （3.32×10^-7A） is present compared with that of device B （8.29×10^-7A）. When the off-state quiescent points Q_2 （V GQ2=-8V, V DQ2=0V） are on, V th hardly shifts for device A while device B shows ＋0.21V positive threshold voltage shift, resulting from the existence of electron traps associated with the dislocations in the UID-GaN buffer layer under the gate. Under pulsed I–V and transconductance G m–V GS measurement, the device with the Fe MD-doped buffer shows more potential in improving reliability upon off-state stress.

In situ confined vertical growth of Co_(2.5)Ni_(0.5)Si_(2)O_(5)(OH)_(4)nanoarrays on rGO for an efficient oxygen evolution reaction

Rational design of oxygen evolution reaction(OER)catalysts at low cost would greatly benefit the economy.Taking advantage of earth-abundant elements Si,Co and Ni,we produce a unique-structure where cobalt-nickel silicate hydroxide[Co_(2.5)Ni_(0.5)Si_(2)O_(5)(OH)_(4)]is vertically grown on a reduced graphene oxide(rGO)support(CNS@rGO).This is developed as a low-cost and prospective OER catalyst.Compared to cobalt or nickel silicate hydroxide@rGO(CS@rGO and NS@rGO,respectively)nanoarrays,the bimetal CNS@rGO nanoarray exhibits impressive OER performance with an overpotential of 307 mV@10 mA cm^(-2).This value is higher than that of CS@rGO and NS@rGO.The CNS@rGO nanoarray has an overpotential of 446 mV@100 mA cm^(-2),about 1.4 times that of the commercial RuO_(2)electrocatalyst.The achieved OER activity is superior to the state-of-the-art metal oxides/hydroxides and their derivatives.The vertically grown nanostructure and optimized metal-support electronic interactions play an indispensable role for OER performance improvement,including a fast electron transfer pathway,short proton/electron diffusion distance,more active metal centers,as well as optimized dualatomic electron density.Taking advantage of interlay chemical regulation and the in-situ growth method,the advanced-structural CNS@rGO nanoarrays provide a new horizon to the rational and flexible design of efficient and promising OER electrocatalysts.

Oxygen Precipitation within Denuded Zone Founded by Rapid Thermal Processing in Czochralski Silicon Wafers

Oxygen precipitation within the magic denuded zone （MDZ） founded by rapid thermal processing in Czochralski silicon （CZ-Si） wafers is investigated. After the standard MDZ process, the CZ-Si wafers are further subjected to two specific oxygen precipitation annealing, respectively. It is found that the MDZs in CZ-Si wafers shrunk notably because oxygen precipitation occurs within the MDZs. However, a width of substantial DZ still remains within the wafer. Therefore, it is believed that the outer region of the MDZs, which corresponds to the oxygen denuded zone formed in the course of rapid thermal process and high temperature annealing, is a substantial defect-free zone which acts as the active area for semiconductor devices.

Raised bed planting promotes grain number per spike in wheat grown after rice by improving spike differentiation and enhancing photosynthetic capacity

The yield of wheat in wheat–rice rotation cropping systems in the Yangtze River Plain, China, is adversely impacted by waterlogging. A raised bed planting(RBP) pattern may reduce waterlogging and increase the wheat yield after rice cultivation by improving the grain number per spike. However, the physiological basis for grain formation under RBP conditions remains poorly understood. The present study was performed over two growing seasons(2018/2019and 2019/2020) to examine the effects of the planting pattern(i.e., RBP and flat planting(FP)) on the floret and grain formation features and leaf photosynthetic source characteristics of wheat. The results indicated that implementation of the RBP pattern improved the soil–plant nitrogen(N) supply during floret development, which facilitated balanced floret development, resulting in a 9.5% increase in the number of fertile florets per spike. Moreover, the RBP pattern delayed wheat leaf senescence and increased the photosynthetic source capacity by 13.9%, which produced more assimilates for grain filling. Delayed leaf senescence was attributed to the resultant high leaf N content and enhanced antioxidant metabolism. Correspondingly, under RBP conditions, 7.6–8.6% more grains per spike were recorded, and the grain yield was ultimately enhanced by 10.4–12.7%. These results demonstrate that the improvement of the spike differentiation process and the enhancement of the leaf photosynthetic capacity were the main reasons for the increased grain number per spike of wheat under the RBP pattern, and additional improvements in this technique should be achievable through further investigation.

Temperature-Dependent Photoluminescence Characteristics of InAs/GaAs Quantum Dots Directly Grown on Si Substrates

The first operation of an electrically pumped 1.3μm InAs/GaAs quantum-dot laser was previously reported epitaxially grown on Si （100） substrate. Here the direct epitaxial growth condition of 1.3μm InAs/OaAs quantum on a Si substrate is further investigated using atomic force microscopy, etch pit density and temperature-dependent photoluminescence （PL） measurements. The PL for Si-based InAs/GaAs quantum dots appears to be very sensitive to the initial OaAs nucleation temperature and thickness with strongest room-temperature emission at 40000 （17Onto nucleation layer thickness）, due to the lower density of defects generated under this growth condition, and stronger carrier confinement within the quantum dots.

Characteristics of In_(0.52)Al_(0.48)As Grown on InP(100) Substrates by Molecular Beam Epitaxy: Growth Optimisation and Effects of Si Doping

Growth of In0.52Al0.48As epilayers on InP (100) substrates by molecular beam epitaxy at a wide range of substrate tempreatures (470~550℃) and at different Si doping levels has been carried out. Low temperature photoluminescence (PL) and double-axis X-ray diffraction (XRD) analyses shaw a strong dependence of the PL and XRD linewidths, XRD intensity ratio (Lepi/Isub), and lattice-mismatch on the substrate temperature. The X-ray diffraction peaks of samples grown at law temperatures show a composition of smaller peaks, indicating the presence of disorder due to alloy clustering. Raman scattering measurements of the same samples show an additional higher energy mode at 273 cm-1 in addition to the InAs-like and AlAs-like longitudinal-optic (LO) phonon modes. Samples doped with Si show an inverted S-shaped dependence of the PL peak energy variation with the temperature which weakens at high doping levels due to a possible reduction in the donor binding energy. Supported be observations of a reduction in both the AlAs-like and InAs-like LO phonon frequencies and a broadening of the LO phonon line shape as the doping level is increased, the PL intensity also shows in increasing degrees at higher doping levels, a temperature dependence which is characteristic of disordered and amorphous materials.