周围空气分子吸附对单分子自旋逻辑门功能性影响的理论研究

单分子自旋逻辑门是分子自旋电子学中重要的功能器件之一.本文将两个二苯并四氮杂[14]轮烯钴配合物分子通过碳原子链相连然后再通过碳原子链连接到(4,4)单壁碳纳米管电极以构成单分子自旋逻辑门器件.利用第一性原理方法研究了周围空气分子吸附对所设计单分子自旋逻辑门器件功能性的影响.理论计算结果表明,所设计的单分子器件根据对输入和输出信号定义的不同可以实现AND、NOR或XNOR逻辑运算功能.将其置于空气中时,CO_(2)气体分子的吸附不影响器件的逻辑运算功能.相反,当O_(2)、N_(2)或H_(2)O分子吸附时,器件不再具有上述逻辑运算功能.进一步分析发现,二苯并四氮杂[14]轮烯钴配合物分子与吸附CO_(2)气体分子间相互作用很.弱,分子器件费米能级附近的电子态几乎不受影响.然而,二苯并四氮杂[14]轮烯钴配合物分子与O_(2)、N_(2)或H_(2)O分子间相互作用较强,导致分子器件费米能级附近的导电态远离费米能级,从而使自旋向上和自旋向下的电子都不导通,进而使逻辑运算功能失效.研究工作表明,周围空气中的气体分子吸附对单分子器件功能性具有重要影响.

Multiple gastric adenocarcinoma of fundic gland type: A case report

BACKGROUND In recent years, there have been reports of a new histological type of gastric cancer, termed gastric adenocarcinoma of the fundic gland (GA-FG). This disease entity presents differentiation towards the fundic gland, especially chief cellpredominant differentiation (GA-FG-CCP). GA-FG-CCP easily invades into the submucosa but rarely shows metastasis. The reports mostly describe primarily single lesions. Herein, we report a case with multiple lesions, and summarize the clinicopathologic characteristics of multiple cases. CASE SUMMARY A 55-year-old woman underwent upper gastrointestinal endoscopy screening. Two whitish lesions on the anterior wall of the gastric corpus and the gastric fundus were detected. The patient had previously received Helicobacter pylori eradication therapy. The mucosa was characterized as grade C-2 atrophic gastritis. We diagnosed the patient with multiple GA-FG (GA-FG-CCP) by hematoxylin and eosin (HE) staining and immunohistochemical staining of the endoscopic biopsy. Upon performing endoscopic submucosal dissection (ESD), one lesion was not found, but the scar from the biopsy was visible;the mucularis mucosa of the biopsy and ESD-resected specimen were intact. The two lesions showed no lymphatic nor venous invasion. The resection performed appeared to be relatively curative. CONCLUSION Cases of multiple GA-FG-CCP are very rare in clinical practice. Most of its clinicopathologic characteristics are similar to those of a single lesion. Our case provides diagnostic and therapeutic information about GA-FG-CCP with multiple lesions.

Tunneling magnetoresistance in ferromagnet/organic-ferromagnet/metal junctions

Spin-dependent transport in ferromagnet/organic-ferromagnet/metal junctions is investigated theoretically.The results reveal a large tunneling magnetoresistance up to 3230%by controlling the relative magnetization orientation between the ferromagnet and the central organic ferromagnet.The mechanism is explained by distinct efficient spin-resolved tunneling states in the ferromagnet between the parallel and antiparallel spin configurations.The key role of the organic ferromagnet in generating the large magnetoresistance is explored,where the spin selection effect is found to enlarge the difference of the tunneling states between the parallel and antiparallel configurations by comparing with the conventional organic spin valves.The effects of intrinsic interactions in the organic ferromagnet including electron–lattice interaction and spin coupling with radicals on the magnetoresistance are discussed.This work demonstrates a promising potential of organic ferromagnets in the design of high-performance organic spin valves.

Theoretical design of single-molecule NOR and XNOR logic gates by using transition metal dibenzotetraaza[14]annulenes

The idea of replacing traditional silicon-based electronic components with the ones assembled by organic molecules to further scale down the electric circuits has been attracting extensive research focuses.Among the molecularly assembled components,the design of molecular logic gates with simple structure and high Boolean computing speed remains a great challenge.Here,by using the state-of-the-art nonequilibrium Green’s function theory in conjugation with first-principles method,the spin transport properties of single-molecule junctions comprised of two serially connected transition metal dibenzotetraaza[14]annulenes(TM(DBTAA),TM=Fe,Co)sandwiched between two single-walled carbon nanotube electrodes are theoretically investigated.The numerical results show a close dependence of the spin-resolved current-voltage characteristics on spin configurations between the left and right molecular kernels and the kind of TM atom in TM(DBTAA)molecule.By taking advantage of spin degree of freedom of electrons,NOR or XNOR Boolean logic gates can be realized in Fe(DBTAA)and Co(DBTAA)junctions depending on the definitions of input and output signals.This work proposes a new kind of molecular logic gates and hence is helpful for further miniaturization of the electric circuits.

Low-Bias Conductance Mechanism of Diarylethene Isomers:a First-Principle Study

The structure-property relationship of diarylethene(DAE)-derivative molecular isomers,which involve ring-closed and ring-open forms,is investigated by employing the nonequilibrium Green’s function formalism combined with density functional theory.Molecular junctions are formed by the isomers connecting to Au(111)electrodes through flanked pyridine groups.The difference in electronic structures caused by different geometry structures for the two isomers,particularly the interatomic alternative single bond and double bond of the ring-closed molecule,contributes to the vastly different low-bias conductance values.The lowest unoccupied molecular orbital(LUMO)of the isomers is the main channel for electron transport.In addition,more electrons transferred to the ring-closed molecular junction in the equilibrium condition,thereby decreasing the LUMO energy to near the Fermi energy,which may contribute to a larger conductance value at the Fermi level.Our findings are helpful for understanding the mechanism of low-bias conductance and are conducive to the design of high-performance molecular switching based on diarylethene or diarylethene-derivative molecules.

Effect of crystallographic orientations on transport properties of methylthiol-terminated permethyloligosilane molecular junction

The understanding of the influence of electrode characteristics on charge transport is essential in the field of molecular electronics.In this work,we investigate the electronic transport properties of molecular junctions comprising methylthiolterminated permethyloligosilanes and face-centered crystal Au/Ag electrodes with crystallographic orientations of(111)and(100),based on the ab initio quantum transport simulations.The calculations reveal that the molecular junction conductance is dominated by the electronic coupling between two interfacial metal–S bonding states,which can be tuned by varying the molecular length,metal material of the electrodes,and crystallographic orientation.As the permethyloligosilane backbone elongates,although theσconjugation increases,the decreasing of coupling induced by the increasing number of central Si atoms reduces the junction conductance.The molecular junction conductance of methylthiol-terminated permethyloligosilanes with Au electrodes is higher than that with Ag electrodes with a crystallographic orientation of(111).However,the conductance trend is reversed when the electrode crystallographic orientation varies from(111)to(100),which can be ascribed to the reversal of interfacial coupling between two metal–S interfacial states.These findings are conducive to elucidating the mechanism of molecular junctions and improving the transport properties of molecular devices by adjusting the electrode characteristics.

Bias-induced reconstruction of hybrid interface states in magnetic molecular junctions

Based on first-principles calculations,the bias-induced evolutions of hybrid interface states inπ-conjugated tricene and in insulating octane magnetic molecular junctions are investigated.Obvious bias-induced splitting and energy shift of the spin-resolved hybrid interface states are observed in the two junctions.The recombination of the shifted hybrid interface states from different interfaces makes the spin polarization around the Fermi energy strongly bias-dependent.The transport calculations demonstrate that in theπ-conjugated tricene junction,the bias-dependent hybrid interface states work efficiently for large current,current spin polarization,and distinct tunneling magnetoresistance.But in the insulating octane junction,the spin-dependent transport via the hybrid interface states is inhibited,which is only slightly disturbed by the bias.This work reveals the phenomenon of bias-induced reconstruction of hybrid interface states in molecular spinterface devices,and the underlying role of conjugated molecular orbitals in the transport ability of hybrid interface states.

Correlation of electrophysiological characteristics Tp-ec and Tp-e/QT with myocardial injury and oxygen free radical generation in patients with acute myocardial infarction

Objective: To study the correlation of electrophysiological characteristics Tp-ec and Tp-e/QT with myocardial injury and oxygen free radical generation in patients with acute myocardial infarction. Methods: Patients who were diagnosed with acute myocardial infarction in our hospital between March 2014 and March 2017 were selected as the AMI group, and healthy subjects who received physical examination were selected as the control group, electrocardiography was done to determine Tp-ec and Tp-e/QT, serum was collected to determine the levels of myocardial injury markers, oxygen free radical generation indexes and apoptosis indexes, and peripheral blood was collected to determine the expression of oxygen free radical generation indexes. Results: Tp-ec and Tp-e/QT of AMI group were significantly higher than those of control group, and serum CK-MB, cTnI, H-FABP, MDA, sTWEAK, sFas and sTRAIL contents as well as peripheral blood Nrf-2, NRE and HO-1 mRNA expression were significantly higher than those of control group and positively correlated with Tp-ec and Tp-e/QT. Conclusion: Electrophysiological characteristics Tp-ec and Tp-e/QT increase, and the transseptal dispersion of repolarization increases in patients with acute myocardial infarction, and they are closely related to myocardial injury and oxygen free radical generation.

Enhancing high-temperature tensile properties of Ni/Ni-W laminated composites for MEMS devices

There is an increasing demand for materials with excellent mechanical performance for Micro-Electro-Mechanical System(MEMS)devices serving at elevated temperatures.However,how to enhance the high-temperature strength of the materials without losing their plasticity is a pending problem.Here,the Ni/Ni-W laminated composites with different monolayer thicknesses and the same ratio of the constituent layer thicknesses were fabricated successfully by using the dual-bath electrodeposition technique.The microstructure stability and tensile properties of annealed Ni/Ni-W laminated composites with different monolayer thicknesses were investigated at 400℃.The results show that the annealed Ni0.5/Ni-W0.05 laminated composites have both high yield strength(450 MPa)and excellent elongation to failure(25.1%)at 400℃,being superior to that of the monotonic Ni(179 MPa and 17.7%).Such a high strength of the laminated composite at 400℃ results from the contribution of the intrinsically high strength of the Ni-W layers with excellent thermal stability,the thickness-constrained effect on grain growth of Ni layers and the interface coupling effect of heterogeneous structures.The good plasticity may be derived from the heterogeneous laminated structure and the decrease in the constituent layer thickness,providing a good co-deformation ability.Basic mechanisms for the high tensile strength and good plasticity of the Ni/Ni-W laminated composites at 400℃ were analyzed theoretically.The findings reveal a potential strategy to fabricate MEMS components with excellent high-temperature tensile properties through tailoring the microstructure thermal stability and the constituent layer scale.

Microstructure Evolution and Tensile Properties of the Alx(CoCrNi)100-x Medium-Entropy Alloys

A series of Alx(CoCrNi)100-x(x=0-21 at.%)medium-entropy alloys(MEAs)were designed and prepared to investigate the effects of Al addition on the microstructures and tensile properties.The results reveal that the lattice structure changes from the initial single FCC structure(x<10 at.%),to the FCC and disordered BCC structures(x=10 and 11 at.%),then to the FCC and BCC/B2 structures(11<x<21 at.%),finally to the duplex BCC/B2 structures(x≥21 at.%)with increasing Al addition.Consistent with microstructures,significant changes also occur in the corresponding tensile properties with Al addition,showing that the strength increases and the ductility decreases with increasing Al addition.Especially,the Al-15 MEA exhibits an acceptable balance of strength and ductility.Furthermore,the mechanism of microstructure evolution and the correlation between microstructures and tensile properties were also discussed and clarified.

Achieving very high cycle fatigue performance of Au thin films for flexible electronic applications

The fatigue damage behavior of the nanocrystalline Au films on polyimide substrates was investigated.It was found that the very high-cycle fatigue damage resistance of the Au film was significantly enhanced by at least a factor of~2 in supported loading through adding an ultrathin Ti interlayer at the Au film/polyimide interface.Such a better fatigue damage resistance is mainly ascribed to the effective suppression of voiding at the Au film/polyimide interface through modulation of the Au/Ti interface,and thus the propensity of the cyclic strain localization and grain boundary cracking is reduced.The finding may provide a potential strategy for the design of flexible devices with ultra-long fatigue life.

Toxicity Classification and Detoxification Strategies of Chinese Materia Medica

In recent years, more and more poison incidents of Chinese Materia Medica(CMM) were reported by China and other countries, which made people to doubt about the safety of CMM, especially for the toxic CMM. In this review, the toxicity of CMM and the toxicity classification of CMM were introduced. And traditional TCM theory and methods particularly used for control and attenuation of CMM's toxicity were described in detail. The traditional processing technology and CMM drug combination were most important detoxifying measures used in CMM formulation and clinical practice. Finally, some factors that have influence on occurrence of CMM's toxicity were discussed such as different species, producing technology and so on.

Mitochondria are Main Targets of Time/Dose-Dependent Oxidative Damage-Based Hepatotoxicity Caused by Rhizoma Dioscoreae Bulbiferae in Mice

Background:Rhizoma Dioscoreae bulbiferae could cause liver damage,which limited its application in the clinic.Aims and Objectives:To explore the mechanism of hepatotoxicity of Rhizoma Dioscoreae bulbiferae in mice.Materials and Methods:In the present study,the water extraction of Rhizoma Dioscoreae bulbiferae(W.E.R)was administrated via intragastrical with Low(19.6 g/kg),Middle(28.0 g/kg),and High(40.0 g/kg)dose in mice.At each time point 14 days,21 days,and 28 days,the body weight,liver coefficient,indexes of liver function alkaline phosphatase(ALP),alanine aminotransferase(ALT)and aspartate transaminase(AST),various biochemical biomarkers of liver tissue and mitochondria were detected and analyzed.Results:We found that W.E.R could decrease the body weight,increase the liver coefficient and the expression levels of indexes of liver function in mice.Next,we investigated that W.E.R could increase the expression levels of reactive oxygen species(ROS)and malondialdehyde(MDA),decrease the expression levels of adenosine triphosphate(ATP)and improve the enzyme activities of total superoxide dismutase(SOD).Third,we found that W.E.R could increase the enzyme activities of manganese-superoxide dismutase,decrease the enzyme activities of sodium-potassium adenosine triphosphatase(Na+-K+-ATPase)and calcium-magnesium adenosine triphosphatase(Ca 2+-Mg 2+-ATPase).Finally,we analyzed that there were significant negative correlations between body weight,expression level of ATP,activity of Na+-K+-ATPase,activity of Ca 2+-Mg 2+-ATPase and time,dose.There were significant positive correlations between liver coefficient,ALP,ALT,AST,expression levels of ROS,MDA and time,dose.Conclusion:All the results above indicated that W.E.R could cause the hepatotoxicity based on the oxidative damage in mice,which and mitochondria might be the main targets.

A unified model for determining fracture strain of metal films on flexible substrates

Failure strain determination of polymer-supported thin films is a key for the design of the flexible devices.A theoretical model R/R0=(L/L0)2(R,L are the electrical resistance and the length of the stretched film,respectively.R0,L0 are the corresponding initial values.)has been widely used to determine the fracture strain of thin films on flexible substrates.However,this equation loses its function in some special cases.Here,a simple and universal theoretical model was proposed to determine the fracture strain of metal thin films on flexible substrates in more generally situations.With this model,we investigated the thicknessdependent failure strains of Cu-5 at.%Al films with thickness of 10 nm,200 nm,1000 nm,and Ti films with thickness of 50 nm,100 nm,300 nm.This model was also employed to study the published data available.The results showed that the new model provided a fairly good prediction of the failure strains of different films.

Screening and Identifying Hepatotoxic Components in Polygoni multiflori Radix and Polygoni multiflori Radix Praeparata

Objective: In this study, the hepatotoxic components of Polygoni multiflori Radix and Polygoni multiflori Radix Praeparata(known as Heshouwu [HSW] and Zhiheshouwu [ZHSW] in China, respectively) were screened, isolated, and identified. Materials and Methods: The ethanol extracts of HSW and ZHSW were separated into 80 fractions according to their polarity in the preparation liquid phase. Chang liver cell line was used to screen the toxic components of HSW and ZHSW in vitro. The obtained toxic mixture was further collected, isolated, and identified to confirm the hepatotoxic compounds of HSW and ZHSW. Results: The identifid hepatotoxic compounds include 2,3,5,4’-tetrah ydroxystilbene-2-O-β-D-glucoside, emodin, physcion-8-O-β-d-glucoside, physcion, and citreorosein, the fist two among them were the main components of HSW and ZHSW. After processing of HSW, the contents of 2,3,5,4’-tetrahydroxystilbene-2-O-β-D-glucoside and emodin in ZHSW were signifiantly decreased. Conclusions: The traditional processing with herb has signifiant effects on the components, especially the toxic components, in the extract of HSW and is an effective method to reduce its toxicity.