Analysis of deformation mechanisms in magnesium single crystals using a dedicated four-point bending tester

In this study,we explored the deformation mechanisms of Mg single crystals using a combination of scanning electron microscopy and electron backscattered diffraction in conjunction with a dedicated four-point bending tester.We prepared two single-crystal samples,oriented along the<1120>and<1010>directions,to assess the mechanisms of deformation when the initial basal slip was suppressed.In the<1120>sample,the primary{1012}twin(T1)was confirmed along the<1120>direction of the sample on the compression side with an increase in bending stress.In the<1010>sample,T1 and the secondary twin(T2)were confirmed to be along the<1120>direction,with an orientation of±60°with respect to the bending stress direction,and their direction matched with(0001)in T1 and T2.This result implies that crystallographically,the basal slip occurs readily.In addition,the<1010>sample showed the double twin in T1 on the compression side and the tertiary twin along the<1010>direction on the tension side.These results demonstrated that the maximum bending stress and displacement changed significantly under the bend loading because the deformation mechanisms were different for these single crystals.Therefore,the correlation between bending behavior and twin orientation was determined,which would be helpful for optimizing the bending properties of Mg-based materials.

Manipulating photogenerated electron flow in nickel single‐atom catalysts for photocatalytic CO_(2) reduction into tunable syngas

The key to designing photocatalysts is to orient the migration of photogenerated electrons to the target active sites rather than dissipate at inert sites.Herein,we demonstrate that the doping of phosphorus(P)significantly enriches photogenerated electrons at Ni active sites and enhances the performance for CO_(2) reduction into syngas.During photocatalytic CO_(2) reduction,Ni single‐atom‐anchored P‐modulated carbon nitride showed an impressive syngas yield rate of 85μmol gcat^(−1)h^(−1) and continuously adjustable CO/H_(2) ratios ranging from 5:1 to 1:2,which exceeded those of most of the reported carbon nitride‐based single‐atom catalysts.Mechanistic studies reveal that P doping improves the conductivity of catalysts,which promotes photogenerated electron transfer to the Ni active sites rather than dissipate randomly at low‐activity nonmetallic sites,facilitating the CO_(2)‐to‐syngas photoreduction process.

Confined cobalt single-atom catalysts with strong electronic metal-support interactions based on a biomimetic self-assembly strategy

Designing high-performance and low-cost electrocatalysts for oxygen evolu-tion reaction(OER)is critical for the conversion and storage of sustainable energy technologies.Inspired by the biomineralization process,we utilized the phosphorylation sites of collagen molecules to combine with cobalt-based mononuclear precursors at the molecular level and built a three-dimensional(3D)porous hierarchical material through a bottom-up biomimetic self-assembly strategy to obtain single-atom catalysts confined on carbonized biomimetic self-assembled carriers(Co SACs/cBSC)after subsequent high-temperature annealing.In this strategy,the biomolecule improved the anchoring efficiency of the metal precursor through precise functional groups;meanwhile,the binding-then-assembling strategy also effectively suppressed the nonspecific adsorption of metal ions,ultimately preventing atomic agglomeration and achieving strong electronic metal-support interactions(EMSIs).Experimental characterizations confirm that binding forms between cobalt metal and carbonized self-assembled substrate(Co–O_(4)–P).Theoretical calculations disclose that the local environment changes significantly tailored the Co d-band center,and optimized the binding energy of oxygenated intermediates and the energy barrier of oxygen release.As a result,the obtained Co SACs/cBSC catalyst can achieve remarkable OER activity and 24 h durability in 1 M KOH(η10 at 288 mV;Tafel slope of 44 mV dec-1),better than other transition metal-based catalysts and commercial IrO_(2).Overall,we presented a self-assembly strategy to prepare transition metal SACs with strong EMSIs,providing a new avenue for the preparation of efficient catalysts with fine atomic structures.

A Hybrid Optimization Approach of Single Point Incremental Sheet Forming of AISI 316L Stainless Steel Using Grey Relation Analysis Coupled with Principal Component Analysiss

We investigated the parametric optimization on incremental sheet forming of stainless steel using Grey Relational Analysis(GRA) coupled with Principal Component Analysis(PCA). AISI 316L stainless steel sheets were used to develop double wall angle pyramid with aid of tungsten carbide tool. GRA coupled with PCA was used to plan the experiment conditions. Control factors such as Tool Diameter(TD), Step Depth(SD), Bottom Wall Angle(BWA), Feed Rate(FR) and Spindle Speed(SS) on Top Wall Angle(TWA) and Top Wall Angle Surface Roughness(TWASR) have been studied. Wall angle increases with increasing tool diameter due to large contact area between tool and workpiece. As the step depth, feed rate and spindle speed increase,TWASR decreases with increasing tool diameter. As the step depth increasing, the hydrostatic stress is raised causing severe cracks in the deformed surface. Hence it was concluded that the proposed hybrid method was suitable for optimizing the factors and response.

Exploration and preliminary clinical investigation of an adhesive approach for primary tooth restoration

The current study aims to investigate a suitable adhesive for primary tooth enamel. Shear bond strength(SBS)of primary teeth and the length of resin protrusion were analyzed using one-way ANOVA with Bonferroni multiple comparison tests after etching with 35% H_(3)PO_(4). SBS and marginal microleakage tests were conducted with Single Bond Universal(SBU)/Single Bond 2(SB2) adhesives with or without pre-etching using a nonparametric Kruskal-Wallis test. Clinical investigations were performed to validate the adhesive for primary teeth restoration using Chi-square tests. Results showed that the SBS and length of resin protrusion increased significantly with the etching time. Teeth in the SBU with 35% H_(3)PO_(4)pre-etching groups had higher bond strength and lower marginal microleakage than those in the SB2 groups. Mixed fractures were more common in the 35% H_(3)PO_(4)etched 30 s + SB2/SBU groups. Clinical investigations showed significant differences between the two groups in cumulative retention rates at the 6-, 12-and 18-month follow-up evaluations, as well as in marginal adaptation, discoloration, and secondary caries at the 12-and 18-month follow-up assessments.Together, pre-etching primary teeth enamel for 30 s before SBU treatment improved clinical composite resin restoration, which can provide a suitable approach for restoration of primary teeth.

Motion Characteristics of Single Electrons of Atoms of Atomic Gas of Hydrogen and Single Electrons of Hydrogen-Like Ions in Form Gas or Vapour during Decays of Such Atoms and Ions. Emission Line Spectra

For the first time the vector differential equation of central motion of single electron in electric field of an atomic nucleus as in external central electric field is set up and solved. Here the following findings are reported. Each of single electrons of a part of atoms of atomic gas of hydrogen and a part of hydrogen-like ions in the form of a gas or a vapour revolves around corresponding atomic nucleus in a flat spiral which has an interior maximum of turns density. The distance between each of these single electrons and corresponding atomic nucleus increases while a speed of single electron decreases. Such motion of single electrons takes place with no expenditures of external energy and points to decays of foregoing parts of atoms and ions. The electric field strength of the atomic nuclei of atoms of atomic gas of hydrogen and hydrogen-like ions in the form of a gas or a vapour is inversely proportional to the distance between the atomic nucleus and the corresponding single electron by greater than the power of 3. Calculated cyclic frequency (rough value 3.5×1014 s-1) of revolution of the electron around the nucleus of atom of atomic gas of hydrogen (in interior maximum of turns density of the flat spiral), which moves at speed 2.2×106 ms-1, and central cyclic frequency of α-line of Balmer series (4.5×1014 s-1) have the same order of magnitude. This fact and line structure of experimental emission line spectra confirm the formation of all lines of these spectra by continuous slight emission of light front by single electrons. The formation of series of lines of emission line spectra is linked to repeated creations of atoms of atomic gas of hydrogen and hydrogen-like ions in the form of a gas or a vapour.

Fabrication and Characteristics of a Si-Based Single Electron Transistor

Si based single electron transistor (SET) is fabricated successfully on p type SIMOX substrate,based on electron beam (EB) lithography,reactive ion etching (RIE) and thermal oxidation.In particular,using thermal oxidation and etching off the oxide layer,a one dimensional Si quantum wire can be converted into several quantum dots inside quantum wire in connection with the source and drain regions.The differential conductance (d I ds /d V ds ) oscillations and the Coulomb staircases in the source drain current ( I ds ) are shown clearly dependent on the source drain voltage at 5 3K.The I ds V gs (gate voltage) oscillations are observed from the I ds V gs characteristics as a function of V gs at different temperatures and various values of V ds .For a SET whose total capacitance is about 9 16aF,the I ds V gs oscillations can be observed at 77K.

Correlation between angiotensinogen gene and primary hypertension with cerebral infarction in the Li nationality of China

Objective To investigate the relationship of four single nucleotide polymorphism （SNP） haplotypes in the angiotensinogen （AGT） gene to the primary hypertension with or without cerebral infarction in the Li nationality of Hainan, China. Methods Total 300 subjects were allocated into three different groups： Groupl, 100 patients who have primary hypertension; Group 2, 100 patients who have primary hypertension with cerebral infarction; and control group, 100 healthy individuals. The genotypes of all subjects were determined by PCR-sequencing to analyze the four poly- morphisms at position - 152 （G-A）, -20 （A-C）, - 18 （C-T）, and -6 （A-G） in the promoter region of AGT. Results The frequen- cies ofCT genotype of AGT-18 and T allele in Group 1 （P = 0.003, P = 0.004） and Group 2 （P = 0.002, P = 0.002） were both significantly higher than in healthy controls. The frequency of G allele of AGT-6 was significantly higher in Group 2 than in the control group （P = 0.016）, while there is no significant difference between Group 1 and the control. Haplotype analysis revealed that H6 haplotype frequency which included -20C and -6G was significantly increased in Group 2 （P = 0.003） compared with the control group, while H5 haplotype frequency which included -20C and -18T was signifi- cantly increased in Group 1 （P = 0.006） versus the control. Conclusion The -20 （A-C） and - 18 （C-T） of the AGT may play an important role in pathogenesis of primary hypertension; and -20 （A-C）, -18 （C-T）, and -6 （A-G） may be the genetic risk factors for the onset of primary hypertension with cerebral infarction in the Li nationality of Halnan, China.

A Model of a Single Electron Transistor of Metallic Tunneling Junctions and Its Validation

Based on the orthodox theory,a model of a single electron transistor （SET） of metallic tunneling junctions is built using the master equation method. Several parameters of the device, such as capacitance, resistance and temperature,are input into the model and thus the I-V curves are attained. These curves are consistent with those from other experiments; therefore, the model is verified. However, there still exists a difference between simulated results and experimental results,mainly comes from the stationary case of the master equation. In other words, precision of simulated results would be increased if the transient case of the master equation is considered. Moreover, the current increases exponentially at higher drain voltages, which is due to the fact that the barrier suppression is caused by the image charge potential.

A Hybrid Random Number Generator Using Single Electron Tunneling Junctions and MOS Transistors

This paper proposes a novel single electron random number generator （RNG）. The generator consists of multiple tunneling junctions （MTJ） and a hybrid single electron transistor （SET）/MOS output circuit. It is an oscillator-based RNG. MTJ is used to implement a high-frequency oscillator, which uses the inherent physical randomness in tunneling events of the MTJ to achieve large frequency drift. The hybrid SET and MOS output circuit is used to amplify and buffer the output signal of the MTJ oscillator. The RNG circuit generates high-quality random digital sequences with a simple structure. The operation speed of this circuit is as high as 1GHz. The circuit also has good driven capability and low power dissipation. This novel random number generator is a promising device for future cryptographic systems and communication applications.

基于GaAs E/D PHEMT工艺的Ku波段双通道幅相控制多功能芯片

基于GaAs增强/耗尽型赝配高电子迁移率晶体管(E/D PHEMT)工艺设计了一款14~18 GHz的双通道多功能芯片。芯片集成了单刀双掷(SPDT)开关、6 bit数控移相器、4 bit数控衰减器和增益补偿放大器。采用正压控制开关以减小控制位数;优化移相、衰减和放大等电路拓扑结构,以获得良好的幅相特性;采用紧凑布局、双通道对称的版图设计,以实现小尺寸和高性能。测试结果表明,+5 V电压下,接收通道增益大于3 dB,1 dB压缩点输出功率大于8 dBm;发射通道增益大于1 dB,1 dB压缩点输出功率大于2 dBm;64态移相均方根误差小于2.5°,16态衰减均方根误差小于0.3 dB,芯片尺寸为3.90 mm×2.25 mm。该多功能芯片可实现对射频信号幅度和相位的高精度控制,可广泛应用于微波收发模块。

Recent advances in regulating the performance of acid oxygen reduction reaction on carbon-supported non-precious metal single atom catalysts

Developing high performance and low-cost catalysts for oxygen reduction reaction(ORR)in challenging acid condition is vital for proton-exchange-membrane fuel cells(PEMFCs).Carbon-supported nonprecious metal single atom catalysts(SACs)have been identified as potential catalysts in the field.Great advance has been obtained in constructing diverse active sites of SACs for improving the performance and understanding the fundamental principles of regulating acid ORR performance.However,the ORR performance of SACs is still unsatisfactory.Importantly,microenvironment adjustment of SACs offers chance to promote the performance of acid ORR.In this review,acid ORR mechanism,attenuation mechanism and performance improvement strategies of SACs are presented.The strategies for promoting ORR activity of SACs include the adjustment of center metal and its microenvironment.The relationship of ORR performance and structure is discussed with the help of advanced experimental investigations and theoretical calculations,which will offer helpful direction for designing advanced SACs for ORR.

The decisive role of adsorbed OH^(*)in low‐potential CO electro‐oxidation on single‐atom catalytic sites

CO impurity-induced catalyst deactivation has long been one of the biggest challenges in proton-exchange membrane fuel cells,with the poisoning phenomenon mainly attributed to the overly strong adsorption on the catalytic site.Here,we present a mechanistic study that overturns this understanding by using Rh-based single-atom catalysis centers as model catalysts.We precisely modulated the chelation structure of the Rh catalyst by coordinating Rh with C or N atoms,and probed the reaction mechanism by surface-enhanced Raman spectroscopy.Direct spectroscopic evidence for intermediates indicates that the reactivity of adsorbed OH^(*),rather than the adsorption strength of CO^(*),dictates the CO electrocatalytic oxidation behavior.The RhN_(4)sites,which adsorb the OH^(*)intermediate more weakly than RhC4 sites,showed prominent CO oxidation activity that not only far exceeded the traditional Pt/C but also the RhC4 sites with similar CO adsorption strength.From this study,it is clear that a paradigm shift in future research should be considered to rationally design high-performance CO electro-oxidation reaction catalysts by sufficiently considering the water-related reaction intermediate during catalysis.

Construction of single chain Fv antibody against transferrin receptor and its protein fusion with alkaline phosphatase

AIM: To construct fusion protein of a single-chain antibody (scFv) against transferrin receptor (TfR) with alkaline phosphatase(AP). METHODS: The VH-linker-VL,namely scFv gene,was prepared by amplifying the VH and VL genes from plasmid pGEM-T-VH and pGEM-T-VL with splicing overlap extension polymerase chain reaction (SOE PCR). After the ScFv gene was modified by 5/71 and Not I,it was subcloned into the secretory expression vector pUC19/119, and then was transformed into E.coli TG1.The positive colonies were screened by colony PCR and their expressions were induced by IPTG.ScFv gene was gained by digesting ScFv expression vector pUC19/119 with 5/71 and NotI restriction enzymes, then subcloned into expression vector pDAP2, followed by transformation in E.coli TG1.The positive colonies were selected by bacterial colony PCR.The expression of fusion protein (scFv-AP) was induced by IPTG.Its activity was detected by enzyme immunoassay. The molecular weights of scFv and scFv-AP were measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). RESULTS: The product of SOE PCR formed a band of 700 bp in agarose gel electrophoresis. SDS-PAGE demonstrated the molecular weight of scFv was 27 ku.Immunofluorescent assay (IFA) demonstrated its reactivity with TfR.The molecular weight of scFv-AP was 75 ku.Enzyme immunoassay showed that scFv-AP could specifically bind to human TfR and play AP activity. CONCLUSION: We have successfully prepared the anti-human TfR scFv and constructed the fusion protein of scFv and AP.It is promising for immunological experiments.

The association between matrix metalloprotease-9 gene polymorphisms and primary angle-closure glaucoma in a Chinese Han population

AIM:To examine the association between the single nucleotide polymorphisms (SNPs)of matrix metalloprotease-9 (MMP-9) gene and primary angleclosure glaucoma(PACG)in a Chinese Han population.METHODS:DNA samples were extracted from peripheral-blood mononuclear cells of 214 PACG patients and 224 healthy controls.Genotyping of rs3918249,rs3918254,rs17577 and rs3787268 in MMP-9was performed using polymerase chain reaction restriction fragment length polymorphism(PCR-RFLP)analysis and the direct sequencing technique.The association between these genetic polymorphisms and risk of PACG was estimated by χ2 test.RESULTS:The distributions of rs3918249,rs3918254,rs17577 and rs3787268 genotypes among cases and healthy controls were compatible with that from HardyWeinberg equilibrium(HWE,P】0.05).The increased frequency of CC and CT genotypes of rs3918254 were observed in PACG patients compared to healthy controls[P=0.006,P corrected(Pcorr)=0.048].The haplotype analysis showed that the CCGG haplotype was nominal associated with PACG(P=0.015),however,the significant was lost when the Bonferroni correction was used(Pcorr=0.105).CONCLUSION:Our results revealed that rs3918254 in MMP-9 may be a susceptible locus to PACG in China,people with the CC and CT genotypes of rs3918254 are more susceptible to PACG.The susceptibility to PACG inChinese Han patients may be not influenced by SNPs rs3918249,rs3787268 and rs17577 in MMP-9.

Preparation, characterization and catalytic performance of single-atom catalysts

Supported and colloidal single‐atom catalysts(SACs),which possess excellent catalytic properties,are particularly important in both fundamental studies and practical applications.The progress made in the preparation methods,characterization,catalytic performances and mechanisms of SACs anchored to metal oxides,two‐dimensional materials and the surface of metal nanoclusters(NCs)are reviewed.The different techniques for SAC fabrication,including conventional solution methods based on co‐precipitation,incipient wetness co‐impregnation,and the chemical vapor deposition method,as well as the newer atom layer deposition(ALD)and galvanic replacement methods,are summarized.The main results from experimental and theoretical studies of various catalytic reactions over SACs,including oxidation reactions,hydrogenation,water gas shift,photocatalytic H2evolution and electrochemical reactions,are also discussed.Moreover,the electronic properties of the single atoms and their interactions with the supports are described to assist in understanding the origin of the high catalytic activity and selectivity of SACs.Finally,possible future research directions of SACs and their applications are proposed.

ETM study of electroporation influence on cell morphology in human malignant melanoma and human primary gingival fibroblast cells

Objective:To estimate electroporation(EP) influence on malignant and normal cells.Methods: Two cell lines including human malignant melanoma(Me-43) and normal human gingival fibroblast(HCFs) were used.EP parameters were the following:230,1000,1 730,2 300 V/cm;30 μ s by 3 impulses for every case.The viability of cells after EP was estimated by MTT assay. The ullrastructural analysis was observed by transmission electron microscope(Zeiss EM 900). Results:In the current study we observed the intracellular effect following EP on Me-43 and HGF cells.At the conditions applied,we did not observe any significant damage of mitochondrial activity in both cell lines treated by EP.Conversely,we showed that EP in some conditions can stimulate cells to proliferation.Some changes induced by EP were only visible in electron microscopy.In fibroblast cells we observed significant changes in lower parameters of EP(230 and 1 000 V/cm).After applying higher electric field intensities(2 300 V/cm) we detected many vacuoles,myelin-like bodies and swallowed endoplasmic reticulum.In melanoma cells such strong pathological modifications after EP were not observed,in comparison with control cells. The ultrastructure of both treated cell lines was changed according to the applied parameters of EP.Conclusions:We can claim that EP conditions are cell line dependent.In terms of the intracellular morphology,human fibroblasts are more sensitive to electric field as compared with melanoma cells.Optimal conditions should be determined for each cell line.Summarizing our study,we can conclude that EP is not an invasive method for human normal and malignant cells. This technique can be safely applied in chemotherapy for delivering drugs into tumor cells.

Electronic interaction between single Pt atom and vacancies on boron nitride nanosheets and its influence on the catalytic performance in the direct dehydrogenation of propane

The electronic metal-support interaction(EMSI)is one of most intriguing phenomena in heterogeneous catalysis.In this work,this subtle effect is clearly demonstrated by density functional theory(DFT)calculations of single Pt atom supported on vacancies in a boron nitride nanosheet.Moreover,the relation between the EMSI and the performance of Pt in propane direct dehydrogenation(PDH)is investigated in detail.The charge state and partial density of states of single Pt atom show distinct features at different anchoring positions,such as boron and nitrogen vacancies(Bvac and Nvac,respectively).Single Pt atom become positively and negatively charged on Bvac and Nvac,respectively.Therefore,the electronic structure of Pt can be adjusted by rational deposition on the support.Moreover,Pt atoms in different charge states have been shown to have different catalytic abilities in PDH.The DFT calculations reveal that Pt atoms on Bvac(Pt-Bvac)have much higher reactivity towards reactant/product adsorption and C–H bond activation than Pt supported on Nvac(Pt-Nvac),with larger adsorption energy and lower barrier along the reaction pathway.However,the high reactivity of Pt-Bvac also hinders propene desorption,which could lead to unwanted deep dehydrogenation.Therefore,the results obtained herein suggest that a balanced reactivity for C–H activation in propane and propene desorption is required to achieve optimum yields.Based on this descriptor,a single Pt atom on a nitrogen vacancy is considered an effective catalyst for PDH.Furthermore,the deep dehydrogenation of the formed propene is significantly suppressed,owing to the large barrier on Pt-Nvac.The current work demonstrates that the catalytic properties of supported single Pt atoms can be tuned by rationally depositing them on a boron nitride nanosheet and highlights the great potential of single-atom catalysis in the PDH reaction.

DNA methyltransferase 3B promoter polymorphism and its susceptibility to primary hepatocellular carcinoma in the Chinese Han nationality population:A case-control study

AIM： To investigate the correlation between C/T single nucleotide polymorphism （SNP） in the promoter of the DNA methyltransferase 3B （D/VMT3B） gene and risk for development and progression of primary hepatocellular carcinoma （HCC）. METHODS： One hundred case subjects were selected consecutively from Tongji Hospital （Wuhan, China）. from March to November 2006. They did not receive radiotherapy or chemotherapy for newly diagnosed and histopathologically confirmed HCC. One hundred and forty control subjects having no history of cancerous or genetic diseases were healthy volunteers to Wuhan Blood Center in the same period. Frequency was matched for sex, age, alcohol consumption and cigarette smoking status of the case subjects. C/T polymorphism of the DNMT3B promoter was analyzed using polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） and sequencing analysis. The association between genotypes of DNMT3B and clinicopathological parameters among cases was also studied. RESULTS： The CC genotype HCC patients and controls. was not detected in both In control subjects, the frequency of TT and CT genotypes was 99.3% and 0.7% respectively, and that of T and C alleles was 99.6% and 0.4% respectively. The frequency of CT genotype was higher in HCC （3.0%）. The frequency of T and C alleles was 98.5% and 1.5% respectively. However, the genotype and allelotype distribution in HCC patients was not significantly different from that in controls. CONCLUSION： C/T polymorphism is not associated with the increased risk of HCC. DNMT3B genetic polymorphism is variable in different races, ethnic groups or geographic areas. Further study is needed to clarify the role of DNMT3B SNP in the development of HCCamong other populations.

LaB_(6)阴极的制备、应用与展望

六硼化镧(LaB_(6))阴极作为一种优异的热发射电子源,应用领域广泛,是高端电子束仪器及设备的关键元器件。本文系统介绍了LaB_(6)材料的制备和加工方法、阴极常见的装卡方式,总结了其在各领域应用现状,并对其发展前景进行了展望。