Ab initio study revealing remarkable oscillatory effects and negative differential resistance in the molecular device of silicon carbide chains.

Inspired by the requirements of miniaturization and multifunction of molecular devices, we investigate the quantum transport properties of three unique molecular devices with silicon carbide chains bridging gold electrodes by an ab initio approach. The pronounced quantum effects, including the oscillation of charge, conductance, and current, together with the negative differential resistance (NDR), have been observed simultaneously over a wide region in the double-chain device. It changes the regular situation that these two effects usually emerge in single-chain systems at the same time. Inspections of the visible differences in the transport behaviors relevant to length and bias between the three devices further evidence that the interchain interaction and molecule-electrode coupling are decisive factors for achieving the quantum effects of oscillation and NDR. These two factors can improve electronic transport capability through enhancing transmission, strengthening the delocalization of frontier molecular orbitals, and reducing potential barriers. Our results not only lay a solid foundation for the application of silicon carbide chains in the miniaturized and multifunctional molecular devices with good performance, but also provide an efficient way to the continuing search for materials with multiple controllable quantum effects in nanoelectronics.

Stability analysis and Hopf bifurcation of a fractional order mathematical model with time delay for nutrient-phytoplankton-zooplankton.

In recent years, some researchers paid their attention to the interaction between toxic phytoplankton and zooplankton. Their studies showed that the mechanism of food selection in zooplankton is still immature and when different algae of the same species (toxic and nontoxic) coexist, some zooplankton may not be able to distinguish between toxic and nontoxic algae, and even show a slight preference for toxic strains. Thus, in this article, a fractional order mathematical model with time delay is constructed to describe the interaction of nutrient-phytoplankton-toxic phytoplankton-zooplankton. The main purpose of this paper is to study the influence of fractional order and time delay on the ecosystem. The sufficient conditions for the existence and local stability of each equilibrium are obtained by using fractional order stability theory. By choosing time delay as the bifurcation parameter, we find that Hopf bifurcation occurs when the time delay passes through a sequence of critical values. After that, some numerical simulations are performed to support the analytic results. At last we make some conclusion and point out some possible future work.

Facile construction of organometallic rotaxane-terminated dendrimers using neutral platinum-acetylides as the main scaffold.

We present the successful construction of a new family of organometallic rotaxane-terminated dendrimers using neutral platinum-acetylides as the main scaffold. The fourth generation dendrimer has 24 rotaxane moieties on the surface termini in a monodisperse manner.

Activation of Chiral (Salen)AlCl Complex by Phosphorane for Highly Enantioselective Cyanosilylation of Ketones and Enones.

Phosphoranes 2 are identified as a class of effective Lewis bases to activate chiral (salen)AlCl complex 1 to enhance its electrophilicity. Accordingly, a three-component catalyst system consisting of complex 1, phosphorane 2e, and Ph3PO is developed as a powerful tool for asymmetric ketone cyanosilylation. In particular, an unprecedented highly enantioselective cyanosilylation of linear aliphatic ketones is achieved. A tandem Wittig-cyanosilylation sequence starting from phosphorane 2a and enals 10 is further achieved, which internally utilizes the Ph3PO byproduct and remaining phosphorane 2a as cocatalysts for cyanosilylation of α,ß,γ,δ-unsaturated enones, providing atom-efficient access to valuable chiral conjugated dienes and enynes. The high efficiency of the cyanosilylation originates from orthogonal activation of both (salen)AlCl complex 1 and cyanotrimethylsilane by the phosphorane and Ph3PO, respectively. This mechanistic insight is supported by NMR, MS, and ReactIR analyses and DFT calculations. Furthermore, the formation of charged complexes through the activation of chiral complex 1 by phosphorane 2a is confirmed by electrical conductivity experiments.

A neutral branched platinum-acetylide complex possessing a tetraphenylethylene core: preparation of a luminescent organometallic gelator and its unexpected spectroscopic behaviour during sol-to-gel transition.

A neutral branched platinum-acetylide complex TPA possessing a tetraphenylethylene core was successfully prepared, which was found to form luminescent organometallic gels in ethyl acetate. Stimulated by temperature or F(-), the reversible gel-sol transition was realized. More interestingly, TPA exhibited an unexpected blue shift of the emission during the sol-to-gel transition.

Recycle waste salt as reagent: a one-pot substitution/Krapcho reaction sequence to α-fluorinated esters and sulfones.

A "one-pot" tandem substitution/Krapcho reaction is reported for the facile synthesis of α-fluorinated esters and sulfones, which utilizes the byproduct salt formed in the substitution step as an indispensible reagent to facilitate the Krapcho reaction step. This represents the first sustainable tandem reaction that internally recycles the waste salt formed in the upstream step as the reagent for the downstream step.

Selective adsorption of L-serine functional groups on the anatase TiO2(101) surface in benthic microbial fuel cells.

To help design bacteria-friendly anodes for unmediated benthic microbial fuel cells (MFCs), we explore the role of anatase TiO2(101) surface biocompatibility in selecting the functional groups of the levo-isomer serine (L-Ser), which contains carboxyl, hydroxyl, and amino groups in a single molecule. By performing total energy calculations and molecular dynamics simulations based on a density-functional tight-binding method, we find that at room temperature, the surface should be active for biomolecules with carboxyl/carboxylic and hydroxyl groups, but it is not sensitive to those with amino groups. The hydrogen bonding between the hydroxyl H and surface O facilitates electron transfer from the pili or the bacterial matrix to the anode surface, which improves the output power density. Thus, in combination with conductive polymers, the anatase TiO2(101) surface can be an effective biocompatible substrate in benthic MFCs by enabling the surface O to form more hydrogen bonds with the hydroxyl H of the biomolecule.

Catalytic functionalization of tertiary alcohols to fully substituted carbon centres.

The catalytic nucleophilic substitution of tertiary alcohols using carbon or heteroatom based nucleophiles is a versatile methodology for the efficient, diverse and atom economical construction of fully substituted carbon centres, including both quaternary carbons and heteroatom substituted tetrasubstituted carbons, which only produces water as the by-product. This review summarizes the recent progress in this field, including the catalytic asymmetric studies and their application in the natural product synthesis, briefly discusses the reaction mechanism and challenges, and outlines synthetic opportunities that are still open.

A systematic review of risk factors for brain metastases and value of prophylactic cranial irradiation in non-small cell lung cancer.

BACKGROUND: The incidence of brain metastases (BM) varies in patients with non-small cell lung cancer (NSCLC), calls into question the value of prophylactic cranial irradiation (PCI). It is possible that clinicopathologic characteristics are associated with the development of BM, but these have yet to be identified in detail. Thus, we conducted the present meta-analysis on risk factors for BM and the value of PCI in patients with NSCLC. METHODS: Eligible data were extracted and the risk factors for BM and the value of PCI in patients with NSCLC were analyzed by calculating the pooled odds ratio (OR). Heterogeneity was detected using Q and I-squared statistics, and publication bias was tested by funnel plots and Egger's test. RESULTS: Six randomized controlled trials with a focus on the value of PCI and 13 eligible studies with a focus on risk factors for BM were included. PCI significantly reduced the incidence of BM in patients with NSCLC (p=0.000, pooled OR=0.34, 95% confidence interval = 0.37-0.59). Compared with non-squamous cell carcinoma, squamous cell carcinoma was associated with a low incidence of BM in patients with NSCLC (p=0.000, pooled OR=0.47, 95% confidence interval =0.34- 0.65). The funnel plot and Egger's test suggested that there was no publication bias in the current meta-analysis. CONCLUSIONS: This meta-analysis provides statistical evidence that compared with non-squamous cell carcinoma, squamous cell carcinoma can be used as a predictor for BM in patients with NSCLC, and PCI might reduce the incidence of BM in patients with NSCLC, but does not provide a survival benefit.

Unexpected self-assembly of chiral triangles from 90° chiral di-Pt(II) acceptors.

Two unexpected chiral organometallic triangles rather than squares from newly designed 90° chiral di-Pt(II) acceptors were obtained through coordination-driven self-assembly. Their structures were well characterized by multinuclear NMR ((1)H and (31)P) and variable-temperature NMR experiments, ESI-TOF-MS, and elemental analysis. The PM6 semiempirical molecular simulation was employed for the interpretation of the formation and stability of such chiral triangles.

One-pot tandem approach to spirocyclic oxindoles featuring adjacent spiro-stereocenters.

All in a sequence: An organocatalyzed Morita-Baylis-Hillman (MBH)/bromination/[3+2] annulation sequence for highly stereoselective syntheses of bis(spirooxindole)s featuring adjacent spiro-stereocenters is described. The key step is an unprecedented catalytic asymmetric [3+2] annulation of isatin-derived MBH adducts, containing a tetrasubstituted alkene moiety, with isatins.

Novel platinum-acetylide metallocycles constructed via a stepwise fragment coupling approach and their aggregation behaviour.

Through a stepwise fragment coupling approach, a family of novel platinum-acetylide metallocycles with well-defined shape and size were successfully constructed. Their aggregation behavior was investigated.

Lysosomal membrane protein TMEM192 deficiency triggers crosstalk between autophagy and apoptosis in HepG2 hepatoma cells.

As constituents of lysosomes, lysosomal membrane proteins play important roles in lysosome-related autophagy and apoptosis. In a recent proteomic study of lysosomal proteins, we identified transmembrane protein 192 (TMEM192) as a novel lysosomal membrane protein candidate. Using specific anti-TMEM192 antibody and lysosomal markers, the lysosomal localization of TMEM192 was determined by immunofluorescence. TMEM192 shows a wide expression pattern in mouse tissues. Interestingly, TMEM192 was found to be highly expressed in tumor cell lines, while it was not expressed or was detected at low levels in normal cell lines. By knockdown of TMEM192 expression using specific siRNAs, we found that TMEM192-deficient HepG2 hepatoma cells show growth inhibition and increased apoptosis. Autophagy was shown to be activated through detection of LC3II expression. Increased apoptosis was inhibited by blocking the expression of the key autophagy gene Atg7 in TMEM192-deficient HepG2 cells. The results suggest that TMEM192 is important for tumor cell growth and proliferation. TMEM192 deficiency can induce autophagy in tumor cells, and can further activate apoptosis by the mitochondrial pathway through autophagy. TMEM192 promotion of autophagy may be a new route for tumor therapy.

Possible cage-like nanostructures formed by amino acids.

We report possible cage-like nanostructures formed by a representative amino acid, serine octamers and decamers, determined by binding energy calculations and molecular dynamic simulations using the density functional tight-binding method. We used the l-handed serine to construct complex conformers linked by hydrogen bonds. We found the structures linked by -COOH···O=C- to be the most stable conformers and the calculation of the vibrational modes of complexes further illustrated this result. We attempted to apply our cage-like structures to the delivery of C(20) and cycloserine as model molecules. Our results may shed light on the design of cage-like biocompatible complexes for drug delivery.

Design and synthesis of 60° dendritic donor ligands and their coordination-driven self-assembly into supramolecular rhomboidal metallodendrimers.

The design and self-assembly of novel rhomboidal metallodendrimers via coordination-driven self-assembly is described. By employing newly designed 60° ditopic donor linkers substituted with Fréchet-type dendrons and appropriate 120° rigid di-Pt(II) acceptor subunits, a variety of [G-1]-[G-3] rhomboidal metallodendrimers with well-defined shape and size were prepared under mild conditions in high yields. The supramolecular metallodendrimers were characterized with multinuclear NMR ((1)H and (31)P), mass spectrometry (CSI-TOF-MS), and elemental analysis. Isotopically resolved mass spectrometry data support the existence of the metallodendrimers with rhomboidal cavities, and NMR data were consistent with the formation of all ensembles. The shape and size of all rhomboidal metallodendrimers were investigated with the PM6 semiempirical molecular orbital method.

Unexpected C-C bond cleavage of epoxide motif: rhodium(I)-catalyzed tandem heterocyclization/[4+1] cycloaddition of 1-(1-alkynyl)oxiranyl ketones.

A rhodium(I)-catalyzed tandem heterocyclization and formal [4+1] cycloaddition of 1-(1-alkynyl)oxiranyl ketones was developed, which provides a general, efficient and practical route to highly substituted furo[3,4-b]furan-3(2H)-ones, wherein the epoxide motif undergo unexpected C-C bond cleavage rather than the classical C-O bond cleavage.

[A study of the histopathological characteristics of nontuberculous mycobacteria lymphadenitis].

OBJECTIVE: To describe the distinctive histopathological changes of nontuberculous mycobacteria lymphadenitis. METHODS: An experimental animal model of nontuberculous mycobacteria lymphadenitis was established and the histopathological changes were observed by light microscope. The paraffin imbedded tissue samples from patients suspected of having lymphoid tuberculosis were also detected by triplex polymerase chain reaction and studied by light microscope. RESULTS: The distinctive histopathological changes of nontuberculous mycobacteria lymphadenitis in the animal model were as follows: (1) Tubercular granuloma formation in lymph nodes which were infected with nontuberculous mycobacteria. Coagulation necrosis was located at the center of the granuloma, and the necrosis looked different from the caseation necrosis caused by mycobacterium tuberculosis. Many neutrophils and their nuclear debris were distributed over the necrosis area. Surrounding the central necrosis area, many epithelioid cells, lymph cells and mononuclear cells could be found. The periphery of the granuloma was surrounded by fibrous tissues. Langhans giant cells could be found in the granuloma and outside the granuloma, while these cells were usually found only in the granuloma of tuberculosis. (2) Serpiginous necrosis was found in the lymph nodes infected with nontuberculous mycobacteria. Many neutrophils and their nuclear debris were distributed over the necrosis area. Around the central necrosis area, many epithelioid cells, lymph cells and mononuclear cells could be found. The fibrous tissues were in the borderline. (3) Star-like necrosis and aristiform necrosis were also found in lymph nodes infected with nontuberculous mycobacteria. A paraffin imbedded tissue sample was detected by triplex polymerase chain reaction and the diagnosis of nontuberculous mycobacteria lymphadenitis was made. In this sample, epithelioid granuloma, serpiginous necrosis and star-like necrosis were found. Neutrophils and their nuclear debris were found distributed over the necrosis area, while epithelioid cells, lymph cells, mononuclear cells and Langhans giant cells were found around the central necrosis area. Polar arrangement of the nuclei of epithelioid cells was evident. The lesion was surrounded by fibrous and collagen tissues. CONCLUSION: Serpiginous, star-like and aristiform necrosis were the distinctive histopathological changes of nontuberculous mycobacteria lymphadenitis. Neutrophils and their nuclear debris were abundant over the necrosis area. Polar arrangement of the nuclei of epithelioid cells was also a distinctive histopathological manifestation.

High-sensitivity matrix-assisted laser desorption/ionization Fourier transform mass spectrometry analyses of small carbohydrates and amino acids using oxidized carbon nanotubes prepared by chemical vapor deposition as matrix.

In matrix-assisted laser desorption/ionization (MALDI) Fourier transform mass spectrometry (FTMS) analyses of small oligosaccharides and amino acids, high sensitivities for oligosaccharides (10 fmol) were obtained by introducing oxidized carbon nanotubes (CNTs) with short and open-end structure as valuable matrix. The CNTs were deposited in porous anodic alumina (PAA) templates by chemical vapor deposition. Transmission electron microscopy (TEM) images show that those CNTs include low levels of amorphous carbon. Thus, the background interference signals generally caused by amorphous carbon powder in CNTs can be reduced effectively. Experiments also confirmed that the FTMS signal intensity of CNTs prepared in PAA template is much lower than that of commercial multi-wall carbon nanotubes (MCNTs). Moreover, the purified process for CNTs with mixed acid (H2SO4 and HNO3) also contributed to the minimization of background. Intense signals corresponding to alkali cation adduct of neutral carbohydrates and amino acids have been acquired. In addition, reliable quantitative analyses for urine and corn root were also achieved successfully. The present work will open a new way to the application of oxidized CNTs as an effective matrix in MALDI MS research.

[Research advances on alpha-fetoprotein physiological function and clinical potential].

Alpha-fetoprotein (AFP), a tumor-associated fetal protein, has been employed as a serum fetal defect/tumor marker to monitor disease progression. Besides this, AFP has many important physiological functions. As a tool of binding and transporting ligands, AFP may bind and transport fatty acids, steroids, heavy metal ions, drugs and some environmental contaminants. As a growth regulator, AFP is capable of both enhancement and inhibition. This function is dose-dependent. The regulatory mechanisms might involve apoptotic regulation, cytoplasmic signaling modulation, and receptor desensitization. As an anticancer drugs-ligand carrier, AFP can transport drugs into target tumor cells by binding AFP receptors overexpressed in the surface of tumor cells, and thus increase antitumor efficiency. In addition, AFP can be employed to chemoprevent breast cancer and possibly other tumors on the basis of its growth suppressive properties.