Scanning tunneling microscopy study of the possible topological surface states in BiTeCl

Recently, the non-centrosymmetric bismuth tellurohalides such as BiTeCl are being studied as possible candidates of topological insulators. While some photoemission studies showed that BiTeCl is an inversion asymmetric topological insulator, others showed that it is a normal semiconductor with Rashba splitting. Meanwhile, first-principle calculationsfailed to confirm the existence of topological surface states in BiTeCl so far. Therefore, the topological nature of BiTeCl requires further investigation. Here we report low temperature scanning tunneling microscopy study on the surface states of BiTeCl single crystals. On the tellurium-terminated surfaces with low defect density, strong evidences for topological surface states are found in the quasi-particle interference patterns generated by the scattering of these states, both in the anisotropy of the scattering vectors and the fast decay of the interference near step edges. Meanwhile, on samples with much higher defect densities, we observed surface states that behave differently. Our results help to resolve the current controversy on the topological nature of BiTeCl.Comment: 13pages,4figure

Anomalous superconducting proximity effect of planar Pb-RhPb2 heterojunctions in the clean limit

Interest in superconducting proximity effect has been revived by the exploitation of Andreev states and by the possible emergence of Majorana bound states at the interface. Spectroscopy of these states has been so far restricted to just a handful of superconductor-metal systems in the diffusion regime, whereas reports in otherwise clean superconductor-superconductor heterojunctions are scarce. Here, we realize molecular beam epitaxy growth of atomically sharp planar heterojunctions between Pb and a topological superconductor candidate RhPb2 that allows us to spectroscopically image the proximity effect in the clean limit. The measured energy spectra of RhPb2 vary with the spatial separation from proximal Pb, and exhibit unusual modifications in the pairing gap structure and size that extend over a distance far beyond the coherence length. This anomalously long-range proximity (LRP) effect breaks the rotational symmetry of Cooper pair potential in real space and largely deforms the Abrikosov vortex cores. Our work opens promising avenues for fundamental studies of the Andreev physics and extraordinary states in clean superconducting heterojunctions.Comment: 8 pages, 4 figure

Comparative studies on the multi-component pharmacokinetics of Aristolochiae Fructus and honey-fried Aristolochiae Fructus extracts after oral administration in rats

PK parameters of 7-OH AA I in rats after oral administration of AF and HAF. (DOC 37 kb

Monitoring specific antibody responses against the hydrophilic domain of the 23 kDa membrane protein of Schistosoma japonicum for early detection of infection in sentinel mice

<p>Abstract</p> <p>Background</p> <p>Schistosomiasis remains an important public health problem throughout tropical and subtropical countries. Humans are infected through contact with water contaminated with schistosome cercariae. Therefore, issuing early warnings on the risk of infection is an important preventive measure against schistosomiasis. Sentinel mice are used to monitor water body infestations, and identifying appropriate antibody responses to schistosome antigens for early detection of infection would help to improve the efficiency of this system. In this study we explored the potential of detecting antibodies to the hydrophilic domain (HD) of the 23-kDa membrane protein (Sj23HD) and soluble egg antigen (SEA) of <it>Schistosome japonicum </it>for early detection of schistosome infection in sentinel mice.</p> <p>Results</p> <p>Development of IgM and IgG antibody levels against Sj23HD and SEA in <it>S. japonicum </it>infected mice was evaluated over the course of 42 days post-infection by enzyme-linked immunosorbent assay (ELISA) and immunoblotting. The Sj23HD and SEA specific IgM and IgG levels in mice all increased gradually over the course of infection, but IgM and IgG antibodies against Sj23HD presented earlier than those against SEA. Furthermore, the rates of positive antibody responses against Sj23HD were higher than those against SEA in the early stage of schistosome infection, suggesting that the likelihood of detecting early infection using anti-Sj23HD responses would be higher than that with anti-SEA responses. The use of immunoblotting could further improve the early detection of schistosome infection due to its greater sensitivity and specificity compared to ELISA. Additionally, the levels of Sj23HD and SEA specific antibodies positively correlated with the load of cercariae challenge and the duration of schistosome infection.</p> <p>Conclusions</p> <p>This study demonstrated that antibody responses to the Sj23HD antigen could be monitored for early detection of schistosome infection in mice, especially by immunoblotting which demonstrated greater sensitivity and specificity than ELISA for detection Sj23HD antibodies.</p

An emerging recombinant human enterovirus 71 responsible for the 2008 outbreak of Hand Foot and Mouth Disease in Fuyang city of China

Hand, foot and mouth disease (HFMD), a common contagious disease that usually affects children, is normally mild but can have life-threatening manifestations. It can be caused by enteroviruses, particularly Coxsackieviruses and human enterovirus 71 (HEV71) with highly variable clinical manifestations. In the spring of 2008, a large, unprecedented HFMD outbreak in Fuyang city of Anhui province in the central part of southeastern China resulted in a high aggregation of fatal cases. In this study, epidemiologic and clinical investigations, laboratory testing, and genetic analyses were performed to identify the causal pathogen of the outbreak. Of the 6,049 cases reported between 1 March and 9 May of 2008, 3023 (50%) were hospitalized, 353 (5.8%) were severe and 22 (0.36%) were fatal. HEV71 was confirmed as the etiological pathogen of the outbreak. Phylogenetic analyses of entire VP1 capsid protein sequence of 45 Fuyang HEV71 isolates showed that they belong to C4a cluster of the C4 subgenotype. In addition, genetic recombinations were found in the 3D region (RNA-dependent RNA polymerase, a major component of the viral replication complex of the genome) between the Fuyang HEV71 strain and Coxsackievirus A16 (CV-A16), resulting in a recombination virus. In conclusion, an emerging recombinant HEV71 was responsible for the HFMD outbreak in Fuyang City of China, 2008

Au@organosilica multifunctional nanoparticles for the multimodal imaging

The increasing application of nanomaterials in biosensor and imaging sets a higher demand on the multifunctionalities of nanomaterials for obtaining multiple parameters of a same system under a same condition. In this work, multifunctional Au@organosilica nanoparticles with high stability were conveniently synthesized by direct hydrolyzing of 3-mercaptopropyltriethoxysilane in an aqueous solution in the presence of a Au core. Modification of the Au core with Raman reporters and the organosilica shell with fluorophore before and after the hydrolysis, respectively, produces multifunctional nanoparticles exhibiting Rayleigh scattering of the Au core, fluorescence signals of the fluorophores and surface-enhanced Raman scattering (SERS) of the Raman reporters. The nanoparticles can be used as multimodal tracers for living cell imaging and related biological research.National Basic Research Program of China[2007CB935603, 2009CB930703, 2007DFC40440]; Natural Science Foundation of China[20620130427, 20825313, 20827003, 21021120456, 21021002

Au@organosilica multifunctional nanoparticles for the multimodal imaging

The increasing application of nanomaterials in biosensor and imaging sets a higher demand on the multifunctionalities of nanomaterials for obtaining multiple parameters of a same system under a same condition. In this work, multifunctional Au@organosilica nanoparticles with high stability were conveniently synthesized by direct hydrolyzing of 3-mercaptopropyltriethoxysilane in an aqueous solution in the presence of a Au core. Modification of the Au core with Raman reporters and the organosilica shell with fluorophore before and after the hydrolysis, respectively, produces multifunctional nanoparticles exhibiting Rayleigh scattering of the Au core, fluorescence signals of the fluorophores and surface-enhanced Raman scattering (SERS) of the Raman reporters. The nanoparticles can be used as multimodal tracers for living cell imaging and related biological research.National Basic Research Program of China[2007CB935603, 2009CB930703, 2007DFC40440]; Natural Science Foundation of China[20620130427, 20825313, 20827003, 21021120456, 21021002

The Charge Transfer Effect of SERS Induced by the Electrochemical Hydrogen Evolution Reaction

应用高灵敏度的共焦显微拉曼技术 ,分别研究了水体系和不同pH值的硫脲体系中电化学反应与表面增强拉曼散射 (SERS)效应之间的关系 .研究结果表明 ,在电化学析氢反应电位区 ,电荷转移增强机制起主要作用 ,使表面物种的拉曼强度显著地增强 .As one of the important mechanisms of SERS, the charge transfer (CT) enhancement requires the strong interaction of the adsorbed species with the substrate in order to permit the transition of charge between the metal Fermi level (energy state) and the molecular orbital [1] . The high enhancement needs the match of the energy gap between the Fermi level (or surface state) and the orbital energy level of the adsorbed molecules with the energy of the incident light. The electrode Fermi level is usually adjusted by the applied potential to satisfy the CT resonance. For the electrochemical reaction process, the frontier orbital energy level of the reacting surface species should be greatly different from that of the adsorbed molecules. Thus, it is interesting to test the additional SERS enhancement induced by the electrochemical reaction. In the present study, the influence of the electrochemical reaction on SERS intensity of thiourea (TU) and water adsorbed on silver electrode surfaces were investigated, respectively. The Raman experiments were performed on a confocal microprobe Raman system (LabRam I). The details of the Raman system and pretreatment of the Ag electrode can be found elsewhere [2] . The SERS spectra of TU in pH 1 and 7 are showed in the Fig. 1 (a) and (b), respectively. The major bands of TU locate at～710 cm -1 and～1 091 cm -1 . The strong 933 cm -1 band is assigned to the symmetric stretching vibration of ClO 4 - as electrolyte anion, which coadsorbed on the surface. The electrochemical measurements indicate that TU can adsorb strongly at Ag electrode in a wide potential region from -0.2 V to -1.5 V (vs SCE). It is of interest that the SERS intensity reaches the maximum at different potential in acidic and neutral solutions. In the low pH solution, one can find that when the electrode potential shifted to -0.8 V, all the band intensities increase remarkably. In the high pH solution (Fig. 1 (b)), at potentials positive of -1.0 V only solution signal can be discerned. The intensity of the surface signals underwent a sharp increase at -1.2 V. Interestingly, we found the maximum intensities in the two pH solutions have a certain relation with the occurrence of the electrochemical hydrogen evolution reaction (HER). A systematic SERS experiments were performed in solutions with pH of 2.0, 2.5, 3..0, 3.5, 4.0 and 7.0 respectively. The profiles of the integrated band intensities (～710 cm -1 ) and the potentials are shown in Fig. 2. It can be found that the maxima of the intensities are located at -0.8 V, -1.1 V for pH 1.0 and 2.0 respectively and -1..2 V for pH 2.5 ～7.0. Correspondingly, the current densities for each potential in different pH solution were presented in Fig. 3. From the two figures, it can be found that the potentials of the maximum intensity of SERS are right at the initial potentials of HER. It implies that there must have some relation between the HER and the additional enhancement of the SERS. A study on the SERS of water will be helpful for further understanding of this relation.作者联系地址：厦门大学固体表面物理化学国家重点实验室!化学系厦门361005,厦门大学固体表面物理化学国家重点实验室!化学系厦门361005,厦门大学固体表面物理化学国家重点实验室!化学系厦门361005,江西师范大学化学系!南昌,330027,厦门大学固体表面物理化学国家重点实验室!化学系厦门361005,Author's Address: 1 State Key Lab. for Phys. Chem. of Sol. Surf., Inst. of Phys. Chem. and Dept. of Chem., Xiamen Univ., Xiamen 361005, China; 2 Dept. of Chem.,

Biomarkers for Early Diagnostic of Mild Cognitive Impairment in Type-2 Diabetes Patients: A Multicentre, Retrospective, Nested Case–Control Study

AbstractBackgroundBoth type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) are common age-associated disorders and T2DM patients show an increased risk to suffer from AD, however, there is currently no marker to identify who in T2DM populations will develop AD. Since glycogen synthase kinase-3β (GSK-3β) activity, ApoE genotypes and olfactory function are involved in both T2DM and AD pathogenesis, we investigate whether alterations of these factors can identify cognitive impairment in T2DM patients.MethodsThe cognitive ability was evaluated using Minimum Mental State Examination (MMSE) and Clinical Dementia Rating (CDR), and the mild cognitive impairment (MCI) was diagnosed by Petersen's criteria. GSK-3β activity in platelet, ApoE genotypes in leucocytes and the olfactory function were detected by Western/dot blotting, the amplification refractory mutation system (ARMS) PCR and the Connecticut Chemosensory Clinical Research Center (CCCRC) test, respectively. The odds ratio (OR) and 95% confidence intervals (95% CI) of the biomarkers for MCI diagnosis were calculated by logistic regression. The diagnostic capability of the biomarkers was evaluated by receiver operating characteristics (ROC) analyses.FindingsWe recruited 694 T2DM patients from Jan. 2012 to May. 2015 in 5 hospitals (Wuhan), and 646 of them met the inclusion criteria and were included in this study. 345 patients in 2 hospitals were assigned to the training set, and 301 patients in another 3 hospitals assigned to the validation set. Patients in each set were randomly divided into two groups: T2DM without MCI (termed T2DM-nMCI) or with MCI (termed T2DM-MCI). There were no significant differences for sex, T2DM years, hypertension, hyperlipidemia, coronary disease, complications, insulin treatment, HbA1c, ApoE ε2, ApoE ε3, tGSK3β and pS9GSK3β between the two groups. Compared with the T2DM-nMCI group, T2DM-MCI group showed lower MMSE score with older age, ApoE ε4 allele, higher olfactory score and higher rGSK-3β (ratio of total GSK-3β to Ser9-phosphorylated GSK-3β) in the training set and the validation set. The OR values of age, ApoE ε4 gene, olfactory score and rGSK-3β were 1.09, 2.09, 1.51, 10.08 in the training set, and 1.06, 2.67, 1.47, 7.19 in the validation set, respectively. The diagnostic accuracy of age, ApoE ε4 gene, olfactory score and rGSK-3β were 0.76, 0.72, 0.66, 0.79 in the training set, and 0.70, 0.68, 0.73, 0.79 in the validation set, respectively. These four combined biomarkers had the area under the curve (AUC) of 82% and 86%, diagnostic accuracy of 83% and 81% in the training set and the validation set, respectively.InterpretationAging, activation of peripheral circulating GSK-3β, expression of ApoE ε4 and increase of olfactory score are diagnostic for the mild cognitive impairment in T2DM patients, and combination of these biomarkers can improve the diagnostic accuracy

A new vesicle trafficking regulator CTL1 plays a crucial role in ion homeostasis

Ion homeostasis is essential for plant growth and environmental adaptation, and maintaining ion homeostasis requires the precise regulation of various ion transporters, as well as correct root patterning. However, the mechanisms underlying these processes remain largely elusive. Here, we reported that a choline transporter gene, CTL1, controls ionome homeostasis by regulating the secretory trafficking of proteins required for plasmodesmata (PD) development, as well as the transport of some ion transporters. Map-based cloning studies revealed that CTL1 mutations alter the ion profile of Arabidopsis thaliana. We found that the phenotypes associated with these mutations are caused by a combination of PD defects and ion transporter misregulation. We also established that CTL1 is involved in regulating vesicle trafficking and is thus required for the trafficking of proteins essential for ion transport and PD development. Characterizing choline transporter-like 1 (CTL1) as a new regulator of protein sorting may enable researchers to understand not only ion homeostasis in plants but also vesicle trafficking in general