Biological Tissue-Inspired Ultrasoft,Ultrathin,and Mechanically Enhanced Microfiber Composite Hydrogel for Flexible Bioelectronics

Hydrogels offer tissue-like softness,stretchability,fracture toughness,ionic conductivity,and compatibility with biological tissues,which make them promising candidates for fabricating flexible bioelectronics.A soft hydrogel film offers an ideal interface to directly bridge thin-film electronics with the soft tissues.However,it remains difficult to fabricate a soft hydrogel film with an ultrathin configuration and excellent mechanical strength.Here we report a biological tissue-inspired ultrasoft microfiber composite ultrathin(<5μm)hydrogel film,which is currently the thinnest hydrogel film as far as we know.The embedded microfibers endow the composite hydrogel with prominent mechanical strength(tensile stress~6 MPa)and anti-tearing property.Moreover,our microfiber composite hydrogel offers the capability of tunable mechanical properties in a broad range,allowing for matching the modulus of most biological tissues and organs.The incorporation of glycerol and salt ions imparts the microfiber composite hydrogel with high ionic conductivity and prominent anti-dehydration behavior.Such microfiber composite hydrogels are promising for constructing attaching-type flexible bioelectronics to monitor biosignals.

A pan-cancer analysis of the biological function and clinical value of BTLA in tumors

B and T-lymphocyte attenuator(BTLA)plays an immunosuppressive role by inhibiting T-and B-cell functions.BTLA is associated with a variety of diseases,especially cancer immunity.However,the function of BTLA in various cancers and its clinical prognostic value have still not been comprehensively analyzed.This study aimed to identify the relationship between BTLA and cancer from the perspectives of differences in BTLA expression,its clinical value,immune infiltration,and the correlation with immune-related genes in various cancers.Data regarding mRNA expression,miRNA expression,lncRNA expression,and clinical data of patients of 33 existing cancers were collected from the TCGA database.Target miRNA of BTLA and the lncRNA that interacts with the target miRNA were obtained from the StarBase database.Based on bioinformatics analysis methods,the relationship between various types of cancers and BTLA was thoroughly investigated,and a competing endogenous RNA network of BTLA,target miRNA,and interacting lncRNA was constructed.The Kaplan-Meier(KM)prognostic analysis of BTLA and target miRNA(has-miR-137)in various types of cancers was completed using the KM plotter.BTLA expression varied in different cancers,with statistical significance in nine cancer types.KM plotter to analyze the overall survival(OS)and regression-free survival prognosis of cancer patients revealed that the BTLA expression was statistically different in the OS of 11 types of cancers out of 21 types of cancers;the OS of 8 type of cancers was also statistically different.Correlation analysis of tumor immune genes revealed a positive correlation of BTLA expression with immunosuppressive gene(CTLA4 and PDCD1)expression.Gene Set Enrichment Analysis showed that BTLA and its co-expressed genes mainly act through biological processes and pathways,including immune response regulation,cell surface receptor signaling pathway,antigen binding,antigen receptor-mediated signaling pathway,and leukocyte migration.BTLA has the potential as a prognostic marker for CLL,COAD,NSCLC,and OV and a diagnostic marker for CLL,COAD,and KIRC.BTLA has a close and complex relationship with the occurrence and development of tumors,and cancer immunotherapy for BTLA is worthy of further analysis.

Transradial versus transfemoral approach for cerebral angiography: A prospective comparison

Objectives: To evaluate the feasibility, efficiency, and safety of the transradial approach(TRA) for cerebral angiography versus the transfemoral approach(TFA) in patients.Methods: In this trial, 2314 patients underwent cerebral angiography, with 1085 patients undergoing the procedure via radial access and 1229 via transfemoral access. The arterial puncture time, operation success rate,oppression time on puncture points, local vascular complication incidence(including bleeding, hematoma, and pseudoaneurysm), deep venous thrombosis of lower limbs(DVT), and bradycardia/hypotension were observed and compared between the two groups.Results: Of the patients who underwent cerebral angiography via radial access, the procedure was successful in1070 patients;compared with 1219 patients with transfemoral access, there was no significant difference(P > 0.05) in the success rate or the arterial puncture time. Radial access patients were less likely to present with oppression time on puncture points, local vascular complications, DVT, and bradycardia/hypotension compared with femoral access patients.Conclusions: For patients undergoing cerebral angiography, radial and femoral approaches are both safe and effective. However, the lower rate of local vascular complications may be a reason to use the radial approach.

VEGF-C/VEGFR-3/iNOS Signaling in Osteosarcoma MG63 Cells Mediates Stimulatory Effects on Human Umbilical Vein Endothelial Cell Proliferation

Objectives To assess the effects of vascular endothelial growth factor-C(VEGF-C)/vascular endothelial growth factor receptor-3(VEGFR-3)signaling on nitric oxide(NO)production and inducible nitric oxide synthase(iNOS)expression in human osteosarcoma MG63 cells and the subsequent impact on the proliferation of human umbilical vein endothelial cells(HUVECs).Methods MG63 cells were treated with VEGF-C alone(VEGF-C group),VEGF-C+iNOS inhibitor aminoguanidine(AG;AG group),and VEGF-C+VEGFR-3 inhibitor MAZ51(MAZ51 group);untreated MG63 cells were used as controls.NO production was evaluated by a colorimetric method involving nitrate reductase.Meanwhile,mRNA and protein levels of iNOS were examined by reverse transcription polymerase chain reaction(RT-PCR)and Western blot.To explore the effect of VEGF-C/VEGFR-3/iNOS signaling of MG63 cells on proliferation of HUVECs,we set up six groups:HUVECs,HUVECs+MG63,HUVECs+VEGF-C,HUVECs+MG63+VEGF-C,HUVECs+MG63+VEGF-C+AG,and HUVECs+MG63+VEGF-C+MAZ51 groups.The proliferation of HUVEC cells was assessed by Cell Counting Kit-8(CCK-8),5-ethynyl-2'-deoxyuridine(EdU)incorporation assay,and proliferating cell nuclear antigen(PCNA)expression quantitation.Results VEGF-C treatment enhanced iNOS expression at both gene and protein levels(mRNA:LSD-t=4.152,P<0.01;protein:LSD-t=3.486,P<0.01)and increased NO release of MG63 cells(LSD-t=3.774,P<0.01);treatment with either AG or MAZ51 decreased these effects(mRNA:LSD-t=9.183,P<0.001;LSD-t=8.639,P<0.001;protein:LSD-t=5.170,P<0.001;LSD-t=7.25S,P<0.001;NO production:LSD-t=10.326,P<0.001;LSD-t=l0.540,P<0.001).Interestingly,co-incubation of HUVECs with MG63 cells and/or VEGF-C significantly promoted HUVEC proliferation(EdU:LSD-t=5.374,P<0.001;LSD-t=2.984,P<0.05;LSD-t=8.526,P<0.001;PCNA:LSD-t=9.267,P<0.001;LSD-t=5.515,P<0.001;LSD-t=14.873,P<0.001).The proliferation effects of HUVEC induced by MG63 cells and VEGF-C attenuated by the treatment of AG(EdU:LSD-t=10.770,P<0.001;PCNA:LSD-t=19.94O,P<0.001)or MAZ51(EdU:LSD-t=6.950,P<0.001;PCNA:LSD-t=14.001,P<0.001).Conclusion In human osteosarcoma MG63 cells,activation of VEGFR-3 by VEGF-C promotes iNOS expression and NO production,which subsequendy induces HUVEC proliferation.

Selection of Landscape Tree Species of Tolerant to Sulfur Dioxide Pollution in Subtropical China

Sulfur dioxide (SO2) is a major air pollutant, especially in developing countries. Many trees are seriously impaired by SO2, while other species can mitigate air pollution by absorbing this gas. Planting appropriate tree species near industrial complexes is critical for aesthetic value and pollution mitigation. In this study, six landscape tree species typical of a subtropical area were investigated for their tolerance of SO2: Cinnamomum camphora (L.) J. Presl., Ilex rotunda Thunb., Lysidice rhodostegia Hance, Ceiba insignis (Kunth) P. E. Gibbs & Semir, Cassia surattensis Burm. f., and Michelia chapensis Dandy. We measured net photosynthesis rate, stomatal conductance, leaf sulfur content, relative water content, relative proline content, and other parameters under 1.31 mg·m-3 SO2 fumigation for eight days. The results revealed that the six species differed in their biochemical characteristics under SO2 stress. Based on these data, the most appropriate species for planting in SO2 polluted areas was I. rotunda, because it grew normally under SO2 stress and could absorb SO2.

Ethylene thiourea exposure induces neurobehavioral toxicity in zebrafish by disrupting axon growth and neuromuscular junctions

Ethylene thiourea(ETU)converted from ethylene bisdithiocarbamate(EBDC)fungicides has aroused great concern because of its prevalence and harmful effects.Although ETU-induced neurotoxicity has been reported,the potential mechanisms remain unclear.This study provided insights into its neurotoxic effects at environmentally relevant concentrations in zebrafish.Our findings showed that embryonic exposure to ETU decreased the hatch rate and delayed somite development.Furthermore,ETU treatment significantly reduced the dark velocity in the locomotion assay.The upregulated tendency of the mitogen-activated protein kinases(MAPK)pathway(mknk1,atf4,mapkapk3)screened by transcriptome analysis implied motor neuron degeneration,which was validated by subsequent morphological observation,as axon length and branches were truncated in the 62.5μg/L ETU group.However,although the rescue experiment with a p38 MAPK inhibitor(SB203580)successfully ameliorated axon degeneration,it failed to reverse the locomotion behaviors.Further exploration of transcriptome data revealed the varied expression of presynaptic scaffold protein-related genes(pcloa,pclob,bsna),whose downregulation might impair the neuromuscular junction(NMJ).Therefore,we reasonably suspected that ETU-induced neurobehavioral deficits might result from the combined effects of the MAPK pathway and presynaptic proteins.Considering this,we highlighted the necessity to take precautions and early interventions for susceptible ETU-exposed populations.

Experimental studies on the energy dissipation of bolted structures with frictional interfaces:A review

Bolted joints play a more and more important role in the structure with lighter weight and heavier load.This paper aims to provide an overview of different experimental approaches for the dynamic behavior of structures in the presence of bolted joints,especially the energy dissipation or damping at frictional interfaces.The comprehension of energy dissipation mechanisms due to friction is provided first,while the key parameters and the measurement techniques,such as the excitation force,the preload of the bolt,or the pressure at the interfaces,are briefly introduced.Secondly,the round-robin systems aim to measure the hysteresis parameters of the frictional joints under tangential loads are reviewed,summarizing the basic theory and the strategies to apply the excitation force or acquire the response in different testing systems.Followed by parameter identification strategies for bolted structures,the test rigs with one or more simplified bolted joints are summarized to give an insight into the understanding of typical characteristics of bolted structures,which are affected by the presence of friction.More complex test rigs hosting real-like or actual engineering structures with bolted lap or flange joints are also introduced to show the identification process of the dynamic characteristics of bolted connections employed in specific applications.Based on the review paper,researchers can get the basic knowledge about the experimental systems of the bolted structures,especially several classical round robin systems,such as the Gaul resonator and widely used Brake-Reußbeam system.Readers can take advantage of this background for more creative and effective future studies,make more progress on the study of assembled structures and understand the influence of bolting frictional connections on the dynamic response better.

Oxygen vacancy promoting artificial atom(RuPd)by d-orbital coupling for efficient water dissociation

Rational design of highly active catalysts for breaking hydrogen-oxygen bonds is of great significance in energy chemical reactions involving water.Herein,an efficient strategy for the artificial atom(RuPd)established by d-orbital coupling and adjusted by oxygen vacancy(V_(O))is verified for water dissociation.As an experimental verification,the turnover frequency of RuPd-TiO_(2)-VO(RuPdTVO)catalyst in ammonia borane hydrolysis reaches up to 2750 min^(−1)(26,190 min−1 based on metal dispersion)in the absence of alkali,exceeding the highest active catalysts(Rh-based catalysts).The d-orbital coupling effect between Ru and Pd simulates the outer electronic structure of Rh.Electron transfer from V_(O) to(RuPd)constructs an electron-rich state of active sites that further enhances the ability of the artificial atom to dissociate water.This work provides an effective electronic regulation strategy from V_(O) and artificial atom constructed by d-orbital coupling effect for efficient water dissociation.

接枝型阳离子淀粉絮凝剂对石材废水的絮凝降浊性能与机理研究

混凝/絮凝工艺是去除废水中悬浮胶体颗粒、降低浊度的有效手段.本研究以一种常见的天然高分子材料——淀粉为原材,以丙烯酰胺和甲基丙烯酰氧乙基三甲基氯化铵为共聚单体,采用接枝共聚技术,开发了一系列接枝链分布相同、但电荷密度及平均接枝链链长不同的接枝型阳离子淀粉改性絮凝剂:淀粉接枝共聚丙烯酰胺-聚甲基丙烯酰氧乙基三甲基氯化铵(St-G).并以一种具有高浊度特征的行业废水——石材废水为研究对象,详细讨论了St-G的结构因素(电荷密度与平均接枝链链长)及环境因素(絮凝剂投加量和pH等)对其絮凝性能的影响,结合絮凝后上清液Zeta电位、絮体结构的动态监测结果以及扩展DLVO(Derjguin-Landau-Verwey-Overbeek)胶体稳定理论等,详细探究了其絮凝机理.研究结果表明,St-G对石材废水的絮凝性能明显优于传统无机混凝剂聚合氯化铝,St-G对石材废水的除浊作用主要是电荷碎片机制为主导,且与黏结架桥作用协同作用的结果.随着St-G电荷密度的增加,其浊度去除率增加而对应最佳絮凝剂用量减少,且絮体破碎后恢复因子增加;而絮体尺寸、絮体生长速度及其破碎因子均与St-G平均接枝链链长呈正相关.扩展DLVO理论结果也表明,St-G与石材废水胶体颗粒间总相互作用能为负值,且与电荷密度呈负相关,其中电荷密度最大的St-G1总相互作用能最低,最易发生电中和混凝作用,具有最佳的降浊效果.综上可知,St-G的制法安全简便、降浊效果显著、绿色环保且价格低廉,在石材加工等行业废水处理中有着良好的应用前景.

Spin-related electronic pathway through single molecule on Au(111)

Spin properties of organic molecules have attracted great interest for their potential applications in spintronic devices and quantum computing.Fe-tetraphenyl porphyrin(Fe TPP)is of particular interest for its robust magnetic properties on metallic substrates.Fe TPP is prepared in vacuum via on-surface synthesis.Molecular structure and spin-related transport properties are characterized by low-temperature scanning tunneling microscope and spectroscopy at 0.5 K.Density functional theory calculations are performed to understand molecular adsorption and spin distribution on Au(111).The molecular structure of Fe TPP is distorted upon adsorption on the substrate.Spin excitations of Fe TPP are observed on the Fe atom and high pyrrole groups in differential conductance spectra.The calculated spin density distribution indicates that the electron spin of Fe TPP is mainly distributed on the Fe atom.The atomic transmission calculation indicates that electrons transport to substrate is mediated through Fe atom,when the tip is above the high pyrrole group.

Construction and electrical control of ultrahigh-density organic memory arrays at cr yog enic temperature

Investigation into the structural and magnetic properties of organic molecules at cryogenic temperature is beneficial for reducing molec-ular vibration and stabilizing magnetization,and is of great im-portance for constructing novel spintronics devices of better perfor-mance and scaling the device size down to nanoscale.In order to explore the possibility of fabricating molecule-based memory chips of ultrahigh density,two-dimensional close-packed molecular arrays with carboxylic acid molecules were constructed in the current work and the magnetic properties in a low-temperature scanning tunnel-ing microscope were also investigated.The results demonstrated that each nonmagnetic molecule can be controllably and independently switched into a stable spin-carrying state at 4 K by applying a voltage pulse with atomic resolution.Benefiting from the small size of a single molecule as the basic storage bit,the two-dimensional molecular ar-rays allowing controllable electrical manipulations on each molecule can behave as a platform of memory chip with an ultrahigh storage density of∼320 terabytes(Tb)(or∼2500 terabits)per square inch.This work highlights the potential and advantage of employing or-ganic molecules in developing future cryogenic information storage techniques and devices at nanoscale.

Nonlinear interval analysis of rotor response with joints under uncertainties

The dynamic influence of joints in aero-engine rotor systems is investigated in this paper.Firstly,the tangential stiffness and loss factor are obtained from an isolated lap joint setup with dynamic excitation experiments.Also,the influence of the normal contact pressure and the excitation level are examined,which revel the uncertainty in joints.Then,the updated Thin Layer Elements(TLEs)method with fitted parameters based on the experiments is established to simulate the dynamic properties of joints on the interface.The response of the rotor subjected to unbalance excitation is calculated,and the results illustrate the effectiveness of the proposed method.Meanwhile,using the Chebyshev inclusion function and a direct iteration algorithm,a nonlinear interval analysis method is established to consider the uncertainty of parameters in joints.The accuracy is proved by comparison with results obtained using the Monte-Carlo method.Combined with the updated TLEs,the nonlinear Chebyshev method is successfully applied on a finite model of a rotor.The study shows that substantial attention should be paid to the dynamical design for the joint in rotor systems,the dynamic properties of joints under complex loading and the corresponding interval analysis method need to be intensively studied.

Interval analysis of rotor dynamic response based on Chebyshev polynomials

Uncertainty is extensively involved in the rotor systems of rotating machinery, which may cause an unstable vibrational response. To take the uncertainty into consideration for the uncertain rotor-bearing system, an improved unified interval analysis method based on the Chebyshev expansion is established in this paper. Firstly, the Chebyshev Interval Method(CIM) to calculate not only the critical speeds but also the dynamic response of rotor with uncertain parameters is introduced. Then, the numerical investigation is carried out based on the developed double disk rotor model and computation procedure, and the results demonstrate the validity. But when the uncertainty is sufficiently large to influence critical speeds, the upper and lower bounds are far from the actual bounds. In order to overcome the defects, a Bound Correction Interval analysis Method(BCIM) is proposed based on the Chebyshev expansion and the modal superposition. In use of the improved method, the bounds of the interval responses, especially the upper bound,are corrected, and the comparison with other methods demonstrates that the higher accuracy and a wider application range.

土壤中四溴双酚A不可提取态残留的降解转化

四溴双酚A(tetrabromobisphenol A, TBBPA)在各种氧化还原状态土壤中均可形成大量的不可提取态残留(nonextractable residues, TBBPA-NER).然而TBBPA-NER在环境中的稳定性和生物可利用性目前还鲜见报道.本研究以TBBPA在淹水条件和有氧条件下分别形成的不可提取态残留(即flooded-nonextractable residues, F-NER和oxicnonextractable residues, O-NER)为研究对象,分析了有氧条件下F-NER的归趋,以及土壤氧化还原状态改变下, FNER和O-NER环境行为的差异;同时研究了水稻根系分泌物对上述过程的影响.结果显示,有氧条件连续培养231 d中, F-NER在土壤中发生了缓慢的生物转化.尽管F-NER在土壤中释放出的可提取态量很低(1%~6%),但是矿化>10%,且酯键和醚键结合部分有所消减.土壤氧化还原状态的改变(即0~50 d有氧, 50~103 d淹水, 103~231 d有氧)对F-NER的矿化影响很小;而TBBPA-NER在土壤中的降解转化受形成条件影响较大,表现为有氧-淹水-有氧培养下F-NER的矿化量,以及释放量均显著高于O-NER. F-NER受环境因素的影响更大,水稻根系分泌物抑制了FNER在有氧环境下的矿化,而淹水条件促进了F-NER的释放产物在土壤中的累积.结果证明,土壤中添加根系分泌物以及氧化还原状态转变等,在不同程度上影响了两种NER在土壤中的生物转化.

Spatio-temporal analysis of phenology in Yangtze River Delta based on MODIS NDVI time series from 2001 to 2015

Phenology has become a good indicator for illustrating the long-term changes in the natural resources of the Yangtze River Delta.However,two issues can be observed from previous studies.On the one hand,existing time-series classification methods mainly using a single classifier,the discrimination power,can become deteriorated due to fluctuations characterizing the time series.On the other hand,previous work on the Yangtze River Delta was limited in the spatial domain (usually to 16 cities)and in the temporal domain (usually 2000-2010).To address these issues,this study attempts to analyze the spatiotemporal variation in phenology in the Yangtze River Delta (with 26 cities,enlarged by the state council in June 2016), facilitated by classifying the land cover types and extracting the phenological metrics based on Moderate Resolution Imaging Spectrometer (MODIS)Normalized Difference Vegetation Index (NDVI)time series collected from 2001 to 2015.First,ensemble learning (EL)-based classifiers are used for land cover classification,where the training samples (a total of 201,597)derived from visual interpretation based on GlobelLand30 are further screened using vertex component analysis (VCA),resulting in 600 samples for training and the remainder for validating. Then,eleven phenological metrics are extracted by TIMESAT (a package name)based on the time series, where a seasonal-trend decomposition procedure based on loess (STL-decomposition)is used to remove spikes and a Savitzky-Golay filter is used for filtering.Finally,the spatio-temporal phenology variation is analyzed by considering the classification maps and the phenological metrics.The experimental results indicate that:1)random forest (R.F)obtains the most accurate classification map (with an overall accuracy higher than 96%);2)different land cover types illustrate the various seasonalities;3)the Yangtze River Delta has two obvious regions,i.e.,the north and the south parts,resulting from different rainfall, temperature,and ecosystem conditions;4)the phenology variation over time is not significant in the study area;5)the correlation between gross spring greenness (GSG) and gross primary productivity (GPP)is very high, indicating the potential use of GSG for assessing the carbon flux.

Effects of Cu^(2+)and humic acids on degradation and fate of TBBPA in pure culture of Pseudomonas sp.strain CDT

Soil contamination with tetrabromobisphenol A（TBBPA） has caused great concerns;however, the presence of heavy metals and soil organic matter on the biodegradation of TBBPA is still unclear. We isolated Pseudomonas sp. strain CDT, a TBBPA-degrading bacterium, from activated sludge and incubated it with ^（14）C-labeled TBBPA for 87 days in the absence and presence of Cu^（2＋）and humic acids（HA）. TBBPA was degraded to organic-solvent extractable（59.4% ± 2.2%） and non-extractable（25.1% ± 1.3%） metabolites,mineralized to CO_2（4.8% ± 0.8%）, and assimilated into cells（10.6% ± 0.9%） at the end of incubation. When Cu^（2＋）was present, the transformation of extractable metabolites into non-extractable metabolites and mineralization were inhibited, possibly due to the toxicity of Cu^（2＋）to cells. HA significantly inhibited both dissipation and mineralization of TBBPA and altered the fate of TBBPA in the culture by formation of HA-bound residues that amounted to 22.1% ± 3.7% of the transformed TBBPA. The inhibition from HA was attributed to adsorption of TBBPA and formation of bound residues with HA via reaction of reactive metabolites with HA molecules, which decreased bioavailability of TBBPA and metabolites in the culture. When Cu^（2＋）and HA were both present, Cu^（2＋）significantly promoted the HA inhibition on TBBPA dissipation but not on metabolite degradation. The results provide insights into individual and interactive effects of Cu^（2＋）and soil organic matter on the biotransformation of TBBPA and indicate that soil organic matter plays an essential role in determining the fate of organic pollutants in soil and mitigating heavy metal toxicity.

Typical Microstructural Characteristics of Ti–5Al–5Mo–5V–3Cr–1Fe Metastable β Ti Alloy Forged in α + β Region

In this study,typical microstructural characteristics of a metastableβTi alloy(Ti–5Al–5Mo–5V–3Cr–1Fe)forged in a dual-phase region(strain of 54%at 820℃)were investigated in detail by the combined use of X-ray diff raction,energy dispersive spectroscopy,electron channeling contrast imaging and electron backscatter diff raction techniques.Results show that the microstructure of the forged alloy is composed of bulkαgrains,αplates andβmatrix.The bulkαgrains correspond to retained primaryαphase(αp,average grain size^2.4μm),while theαplates are secondaryαphase(αs,width^70 nm)precipitated from theβmatrix during air cooling.During forging,theβmatrix experiences dynamic recovery with many subgrains and signifi cant orientation gradients formed.Analyses of the orientation relationship between theαandβphases show that the Burgers orientation relationship is not maintained between someα_p andβphases,which should be related to thermal deformation-induced changes of their orientations.In contrast,all of theαs plates are found to maintain well the Burgers orientation relationship with theβphase.

Conductance of a single molecule C_(60)-SnPc heterojunction

Geometries of molecule-molecule interfaces strongly influence the current passing from one molecule to another. The contact conductance of molecule-molecule junctions which consist of fullerene and tin phthalocyanine molecules is investigated with a low-temperature scanning tunneling microscope. Two types of molecules are deposited onto Cu(111). Fullerene molecules are transferred to tips through controlled contact of STM tips on molecules. The molecule-molecule junctions are formed by approaching fullereneterminated tips to tin phthalocyanine molecules on Cu(111). Our experimental method can be extended to study the intermolecular charge transport of a range of molecular junctions.

Study on dynamic stiffness of supporting structure and its influence on vibration of rotors

The dynamic response of the rotor depends on not only itself but also the dynamical characteristics of the structures that support it. In this paper, the coupling vibration characteristics of the rotor and supporting structure are studied using one simple rotor-supports model firstly, and then the dynamic stiffness of the typical supporting structure of an aero-engine is investigated in use of both numerical and experimental methods. While, one simulation strategy is developed to include dynamic stiffness of realistic supports in the dynamical analysis of the rotor system. The simulated and tested results show that the dynamic stiffness of the supporting structure not only depends on the structural parameters but also is related to the frequency of the excitation force. The dynamic stiffness is affected by the damping and inertia effect when the excitation frequency is high and closed to the resonance frequency of the support, which may decrease the dynamic stiffness sharply.More resonance frequencies may be induced and the critical speed could be reduced or increased.While higher vibration response peak and overload of the bearing may also be caused by the varied dynamic stiffness, which needs to be avoided in the design of the rotor-supports system.

Self-assembly of L-tryptophan on Cu(111) studied by low-temperature scanning tunneling microscopy

The self-assembly of L-tryptophan on Cu(111) is investigated by an ultrahigh vacuum scanning tunneling microscope(STM) at 4.4 K.When deposited onto the substrate at around 120 K with a coverage of 0.1 monolayer,molecular trimers,tetramers,hexamers,and chains coexist on Cu(111).Then almost all molecules self-assemble into chiral hexamers after being annealed at room temperature.When increasing molecular coverage to the full layer,a new type of chain is observed on the surface.Based on the high-resolution STM images at sub-molecular level,we suggest that the L-tryptophan molecules are present in neutral,zwitterionic or anionic states in these structures.