Intrinsic Two-Dimensional Organic Topological Insulators in Metal-Dicyanoanthracene Lattices

We predict theoretical existence of intrinsic two-dimensional organic topological insulator (OTI) states in Cu-dicyanoanthracene (DCA) lattice, a system that has also been grown experimentally on Cu substrate, based on first-principle density functional theory calculations. The pz-orbital Kagome bands having a Dirac point lying exactly at the Fermi level are found in the freestanding Cu-DCA lattice. The tight-binding model analysis, the calculated Chern numbers, and the semi-infinite Dirac edge states within the spin-orbit coupling gaps all confirm its intrinsic topological properties. The intrinsic TI states are found to originate from a proper number of electrons filling of the hybridized bands from Cu atomic and DCA molecular orbitals based on which similar lattices containing noble metal atoms (Au and Cu) and those molecules with two CN groups (DCA and cyanogens) are all predicted to be intrinsic OTIs.

Formation of Ideal Rashba States on Layered Semiconductor Surfaces Steered by Strain Engineering

Spin splitting of Rashba states in two-dimensional electron system provides a promising mechanism of spin manipulation for spintronics applications. However, Rashba states realized experimentally to date are often outnumbered by spin-degenerated substrate states at the same energy range, hindering their practical applications. Here, by density functional theory calculation, we show that Au one monolayer film deposition on a layered semiconductor surface β-InSe(0001) can possess "ideal" Rashba states with large spin splitting, which are completely situated inside the large band gap of the substrate. The position of the Rashba bands can be tuned over a wide range with respect to the substrate band edges by experimentally accessible strain. Furthermore, our nonequilibrium Green's function transport calculation shows that this system may give rise to the long-sought strong current modulation when made into a device of Datta-Das transistor. Similar systems may be identified with other metal ultrathin films and layered semiconductor substrates to realize ideal Rashba states.

Development of microsatellite markers for Suriana maritima (Surianaceae) using next-generation sequencing technology

Our objective was to develop microsatellite markers for use in assessing genetic variation in the small shrub or tree species Suriana maritima (Surianaceae). In China, this species is found only as a few fragmented populations and individuals on the Paracel Islands. Using next-generation genome sequencing methodology, we developed 17 novel microsatellite markers for S. maritima. Fifty-four individuals from six populations of S. maritima were examined for polymorphisms; only one allele was detected for each of the markers. Microsatellite loci developed indicate a complete absence of genetic diversity for S. maritima on the Paracel Islands in China. These markers will be useful for examining genetic variation among S. maritima populations in other areas of the world.

Highly Anisotropic Dirac Fermions in Square Graphynes

We predict a family of 2D carbon (C) allotropes, square graphynes (S-graphynes) that exhibit highly anisotropic Dirac fermions, using first-principle calculations within density functional theory. They have a square unit-cell containing two sizes of square C rings. The equal-energy contour of their 3D band structure shows a crescent shape, and the Dirac crescent has varying Fermi velocities from 0.6 × 10(5) to 7.2 × 10(5) m/s along different k directions. Near the Fermi level, the Dirac crescent can be nicely expressed by an extended 2D Dirac model Hamiltonian. Furthermore, tight-binding band fitting reveals that the Dirac crescent originates from the next-nearest-neighbor interactions between C atoms. S-graphynes may be used to build new 2D electronic devices taking advantages of their highly directional charge transport.

Diurnal and temporal variations of water-soluble dicarboxylic acids and related compounds in aerosols from the northern vicinity of Beijing: implication for photochemical aging during atmospheric transport

Aerosol samples were collected in autumn 2007 on day- and nighttime basis in the northern receptor site of Beijing, China. The samples were analyzed for total carbon (TC) and water-soluble dicarboxylic acids (C2-C12), oxocarboxylic acids (C2-C9), glyoxal and methylglyoxal to better understand the photochemical aging of organic aerosols in the vicinity of Beijing. Concentrations of TC are 50% greater in daytime when winds come from Beijing than in nighttime when winds come from the northern forest areas. Most diacids showed higher concentrations in daytime, suggesting that the organics emitted from the urban Beijing and delivered to the northern vicinity in daytime are subjected to photo-oxidation to result in diacids. However, oxalic acid (C2), which is the most abundant diacid followed by C3 or C4, became on average 30% more abundant in nighttime together with azelaic, ω-oxooctanoic and ω-oxononanoic acids, which are specific oxidation products of biogenic unsaturated fatty acids. Methylglyoxal, an oxidation product of isoprene and a precursor of oxalic acid, also became 29% more abundant in nighttime. Based on a positive correlation between C2 and glyoxylic acid (ωC2) in nighttime when relative humidity significantly enhanced, we propose a nighttime aqueous phase production of C2 via the oxidation of ωC2. We found an increase in the contribution of diacids to TC by 3 folds during consecutive clear days. This study demonstrates that diacids and related compounds are largely produced in the northern vicinity of Beijing via photochemical processing of organic precursors emitted from urban center and forest areas.

Synthesis, in vitro protoporphyrinogen oxidase inhibition, and herbicidal activity of N-(benzothiazol-5-yl)hexahydro-1H-isoindole-1,3-diones and N-(benzothiazol-5-yl)hexahydro-1H-isoindol-1-ones

Protoporphyrinogen oxidase (EC 1.3.3.4) is one of the most significant targets for a large family of herbicides. As part of our continuous efforts to search for novel protoporphyrinogen oxidase-inhibiting herbicides, N-(benzothiazol-5-yl)tetrahydroisoindole-1,3-dione was selected as a lead compound for structural optimization, leading to the syntheses of a series of novel N-(benzothiazol-5-yl)hexahydro-1H-isoindole-1,3-diones (1a-o) and N-(benzothiazol-5-yl)hexahydro-1H-isoindol-1-ones (2a-i). These newly prepared compounds were characterized by elemental analyses, (1) H NMR, and ESI-MS, and the structures of 1h and 2h were further confirmed by X-ray diffraction analyses. The bioassays indicated that some compounds displayed comparable or higher protoporphyrinogen oxidase inhibition activities in comparison with the commercial control. Very promising, compound 2a, ethyl 2-((6-fluoro-5-(4,5,6,7-tetrahydro-1-oxo-1H-isoindol-2(3H)-yl)benzo[d]thiazol-2-yl)-sulfanyl)acetate, was recognized as the most potent candidate with K(i) value of 0.0091 μm. Further greenhouse screening results demonstrated that some compounds exhibited good herbicidal activity against Chenopodium album at the dosage of 150 g/ha.

Tuning topological edge states of Bi(111) bilayer film by edge adsorption

Based on first-principles and tight-binding calculations, we report that the topological edge states of zigzag Bi(111) nanoribbon can be significantly tuned by H edge adsorption. The Fermi velocity is increased by 1 order of magnitude, as the Dirac point is moved from the Brillouin zone boundary to the Brillouin zone center, and the real-space distribution of Dirac states are made twice more delocalized. These intriguing changes are explained by an orbital filtering effect of edge H atoms, which pushes certain components of the p orbital of edge Bi atoms out of the band gap regime that reshapes the topological edge states. In addition, the spin texture of the Dirac states is also modified, which is described by introducing an effective Hamiltonian. Our findings not only are of fundamental interest but also have practical implications in potential applications of topological insulators.

Aspirin-triggered Lipoxin A4 attenuates mechanical allodynia in association with inhibiting spinal JAK2/STAT3 signaling in neuropathic pain in rats

Aspirin-triggered Lipoxin A4 (ATL), as a Lipoxin A4 (LXA4) epimer, is endogenously produced by aspirin-acetylated cycloxygenase-2 (COX-2) and plays a vital role in endogenous anti-inflammation via the LXA4 receptor (ALX). Recent investigations have indicated that spinal neuroinflammation and the activation of the Janus Kinase 2 (JAK2)/Signal Transducers and Transcription Activators 3 (STAT3) signaling pathway are involved in neuropathic pain states. However, the effect of ATL on neuroinflammation and JAK2/STAT3 signaling in chronic constriction injury (CCI)-induced neuropathic pain in rats has not been well-studied. The present study demonstrated the anti-inflammatory and analgesic effect of ATL on neuropathic pain and assessed the role of spinal JAK2/STAT3 signaling on the effect of ATL. Intrathecal administration of ATL significantly attenuated mechanical allodynia via spinal ALX and inhibited the upregulation of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) on day 7 of CCI surgery. In addition, ATL markedly suppressed the upregulation of p-STAT3 induced by the neuropathic pain. Blockade of JAK2-STAT3 signaling with intrathecal administration of the JAK2 inhibitor AG490 or the STAT3 inhibitor S3I-201 clearly reduced mechanical allodynia and the upregulation of pro-inflammatory cytokines in CCI rats. Interestingly, inhibition of JAK2/STAT3 signaling via ATL or the specific signaling inhibitor (AG49, S3I-201) further promoted the increased expression of suppressor of cytokine signaling 3 (SOCS3) mRNA in the spinal cord induced by CCI surgery. Taken together, our results suggested that the analgesic effect of ATL was mediated by inhibiting spinal JAK2/STAT3 signaling and hence the spinal neuroinflammation in CCI rats.

Wet deposition of acidifying substances in different regions of China and the rest of East Asia: modeling with updated NAQPMS

The traditional way to study Sources-Receptor Relationships (SRRs) of wet deposition is based on sensitivity simulation, which has weakness in dealing with the non-linear secondary formation pollutants (e.g. ozone and nitrate). An on-line source tracking method has been developed in the Nested Air Quality Prediction Modeling System (NAQPMS) coupled with cloud-process module for the first time. The new model can not only quantify the total volume of the sulfate, nitrate and ammonium wet deposition with more accuracy, but also trace these acidic species to their emitted precursors. Compared with previous studies, our result clearly shows: (1) East China and Central China, which are the two primary export regions, have 15-30% and 10% effect on wet deposition in other areas, respectively; (2) Besides the above two regions, the total acid deposition in Southwestern and Northeastern China have reached or exceeded the critical loads under their own environmental conditions.

Using Bayesian optimization method and FLEXPART tracer model to evaluate CO emission in East China in springtime

Carbon monoxide (CO) is of great interest as a restriction factor for pollutants related to incomplete combustions. This study attempted to evaluate CO emission in East China using the analytical Bayesian inverse method and observations at Mount Hua in springtime. The mixing ratio of CO at the receptor was calculated using 5-day source-receptor relationship (SRR) simulated by a Lagrangian Particle Dispersion Model (FLEXPART) and CO emission flux. The stability of the inversion solution was evaluated on the basis of repeated random sampling simulations. The inversion results demonstrated that there were two city cluster regions (the Beijing-Tianjin-Hebei region and the low reaches of the Yangtze River Delta) where the difference between a priori (Intercontinental Chemical Transport Experiment-Phase B, INTEX-B) and a posteriori was statistically significant and the a priori might underestimate the CO emission flux by 37 %. A correction factor (a posteriori/a priori) of 1.26 was suggested for CO emission in China in spring. The spatial distribution and magnitude of the CO emission flux were comparable to the latest regional emission inventory in Asia (REAS2.0). Nevertheless, further evaluation is still necessary in view of the larger uncertainties for both the analytical inversion and the bottom-up statistical approaches.

Coupled Dirac fermions and neutrino-like oscillations in twisted bilayer graphene

The low-energy quasiparticles in graphene can be described by a Dirac-Weyl Hamiltonian for massless fermions, hence graphene has been proposed to be an effective medium to study exotic phenomena originally predicted for relativistic particle physics, such as Klein tunneling and Zitterbewegung. In this work, we show that another important particle-physics phenomenon, the neutrino oscillation, can be studied and observed in a particular graphene system, namely, twisted bilayer graphene. It has been found that graphene layers grown epitaxially on SiC or by the chemical vapor deposition method on metal substrates display a stacking pattern with adjacent layers rotated by an angle with respect to each other. The quasiparticle states in two distinct graphene layers act as neutrinos with two flavors, and the interlayer interaction between them induces an appreciable coupling between these two "flavors" of massless fermions, leading to neutrino-like oscillations. In addition, our calculation shows that anisotropic transport properties manifest in a specific energy window, which is accessible experimentally in twisted bilayer graphene. Combining two graphene layers enables us to probe the rich physics involving multiple interacting Dirac fermions.

Spatially separated spin carriers in spin-semiconducting graphene nanoribbons

A graphene nanoribbon with sawtooth edges has a ferromagnetic ground state. Using first-principles and tight-binding model calculations, we show that, under a transverse electrical field, the sawtooth graphene nanoribbons become a spin semiconductor whose charge carriers are not only spin polarized in energy space but also spatially separated at different edges. Low-energy excitation produces spin-up electrons localized at one edge and spin-down holes at the opposite edge, and the excitation energy of spin carries can be tuned by the electric field to reach a new state of spin gapless semiconductor. Also, the spin semiconducting states are shown to be robust against at least 10% edge disorder. These features demonstrate a good tunability of spin carriers for spintronics applications.

Computational and experimental insights into the mechanism of substrate recognition and feedback inhibition of protoporphyrinogen oxidase

Protoporphyrinogen IX oxidase (PPO; EC 1.3.3.4) is an essential enzyme catalyzing the last common step in the pathway leading to heme and chlorophyll biosynthesis. Great interest in PPO inhibitors arises from both its significance to agriculture and medicine. However, the discovery of PPO inhibitors with ultrahigh potency and selectivity is hampered due to lack of structural and mechanistic understanding about the substrate recognition, which remains a longstanding question central in porphyrin biology. To understand the mechanism, a novel binding model of protogen (protoporphyrinogen IX, the substrate) was developed through extensive computational simulations. Subsequently, amino acid residues that are critical for protogen binding identified by computational simulations were substituted by mutagenesis. Kinetic analyses of these mutants indicated that these residues were critical for protogen binding. In addition, the calculated free energies of protogen binding with these mutants correlated well with the experimental data, indicating the reasonability of the binding model. On the basis of this novel model, the fundamental mechanism of substrate recognition was investigated by performing potential of mean force (PMF) calculations, which provided an atomic level description of conformational changes and pathway intermediates. The free energy profile revealed a feedback inhibition mechanism of proto (protoporphyrin IX, the product), which was also in agreement with experimental evidence. The novel mechanistic insights obtained from this study present a new starting point for future rational design of more efficient PPO inhibitors based on the product-bound PPO structure.

Antiproliferative triterpenoid saponins from the stem of Psychotria sp

Six new triterpenoid saponins, psychotrianosides A-F (1-6), and two known triterpenoid saponins, psychotrianoside G (7) and ardisianoside D (8), were isolated from Psychotria sp. Their structures were determined mainly by spectroscopic methods. The cytotoxic activities of 1-8 against five human cancer cell lines (MDA-MB-231, MCF-7, MCF-7/ADM, HepG2, and HepG2/ADM) are reported for the first time. Psychotrianoside C (3) showed the most potent antiproliferative activity among these saponins, and the IC50 value of 3 against MDA-MB-231 was 2.391 ± 0.161 µM. Compound 3 was also found to induce apoptosis.

Prediction of a two-dimensional organic topological insulator

Topological insulators (TI) are a class of materials exhibiting unique quantum transport properties with potential applications in spintronics and quantum computing. To date, all of the experimentally confirmed TIs are inorganic materials. Recent theories predicted the possible existence of organic TIs (OTI) in two-dimensional (2D) organometallic frameworks. However, those theoretically proposed structures do not naturally exist and remain to be made in experiments. Here, we identify a recently experimentally made 2D organometallic framework, consisting of π-conjugated nickel-bis-dithiolene with a chemical formula Ni3C12S12, which exhibits nontrivial topological states in both a Dirac band and a flat band, therefore confirming the existence of OTI.

Quantum anomalous Hall effect in 2D organic topological insulators

The quantum anomalous Hall effect (QAHE) is a fundamental transport phenomenon in the field of condensed-matter physics. Without an external magnetic field, spontaneous magnetization combined with spin-orbit coupling gives rise to a quantized Hall conductivity. So far, a number of theoretical proposals have been made to realize the QAHE, but all based on inorganic materials. Here, using first-principles calculations, we predict a family of 2D organic topological insulators for realizing the QAHE. Designed by assembling molecular building blocks of triphenyl-transition-metal compounds into a hexagonal lattice, this new class of organic materials is shown to have a nonzero Chern number and exhibits a gapless chiral edge state within the Dirac gap.

Aeroelasticity-based fluid agitation for lab-on-chips

In this study, we report a robust agitation method for small-volume liquids. It utilizes an elastic diaphragm as the bottom of a liquid chamber, upon which an initial tension is also applied to enhance the aeroelasticity effects at small/micro scales. As a result, spontaneous vibration of the diaphragm can be induced by an external air flow, which further provides fluid agitations. The device structure is simple and can be easily fabricated at low cost. More importantly, the vibration amplitude is controllable and varies widely from several tens to several hundred micrometers depending on the applied air pressure. The resulting agitation is effective and applicable at high viscosities of up to 900 cSt. The influences of air pressure and liquid viscosity on the vibration frequency are discussed. Potential applications of this technique for solid particle agitation, focusing and fluid mixing are also demonstrated.

[Construction and preliminary applications of a Saccharomyces cerevisiae detection plasmid using for screening promoter elements]

Synthetic biology of natural products is the design and construction of new biological systems by transferring a metabolic pathway of interest products into a chassis. Large-scale production of natural products is achieved by coordinate expression of multiple genes involved in genetic pathway of desired products. Promoters are cis-elements and play important roles in the balance of the metabolic pathways controlled by multiple genes by regulating gene expression. A detection plasmid of Saccharomyces cerevisiae was constructed based on DsRed-Monomer gene encoding for a red fluorescent protein. This plasmid was used for screening the efficient promoters applying for multiple gene-controlled pathways. First of all, eight pairs of primers specific to DsRed-Monomer gene were synthesized. The rapid cloning of DsRed-Monomer gene was performed based on step-by-step extension of a short region of the gene through a series of PCR reactions. All cloned sequences were confirmed by DNA sequencing. A vector named pEASYDs-M containing full-length DsRed-Monomer gene was constructed and was used as the template for the construction of S. cerevisiae expression vector named for pYeDP60-Ds-M. pYeDP60-Ds-M was then transformed into S. cerevisiae for heterologous expression of DsRed-Monomer gene. SDS-PAGE, Western blot and fluorescence microscopy results showed that the recombinant DsRed-Monomer protein was expressed successfully in S. cerevisiae. The well-characterized DsRed-Monomer gene was then cloned into a yeast expression vector pGBT9 to obtain a promoter detection plasmid pGBT9Red. For determination efficacy of pGBT9Red, six promoters (including four inducible promoters and two constitutive promoters) were cloned by PCR from the S. cerevisiae genome, and cloned into pGBT9Red by placing upstream of DsRed-Monomer gene, separately. The fluorescence microscopy results indicated that the six promoters (GAL1, GAL2, GAL7, GAL10, TEF2 and PGK1) can regulate the expression of DsRed-Monomer gene. The successful construction of pGBT9Red lays the foundation for further analysis of promoter activity and screening of promoter element libraries.

Sensitive measurement of polyols in urine by capillary zone electrophoresis coupled with amperometric detection using on-column complexation with borate

Little is known about human polyol metabolism, but recent studies indicate that abnormal polyol concentrations in body fluids are related to several diseases. In this study, a rapid and sensitive method for the determination of seven major polyols in urine including two groups of polyol isomers, C5-polyols (Rib+Arb+Xyl) and C6-polyols (Sor+Gal+Man), was developed using capillary zone electrophoresis coupled with amperometric detection (CZE-AD). The effects of the working electrode potential, pH, running buffer components and concentrations, separation voltage and injection times were investigated. Under the optimised conditions, seven types of polyols could be perfectly separated via the formation of anionic polyol-borate complexes in a borate buffer solution. Highly linear current responses to the polyol concentrations were obtained with good correlation (0.9984<R(2)<0.9997), and the limits of detection (LODs) ranged from 1.33×10(-6) to 5.8×10(-7) mol L(-1) (S/N=3). The proposed method has been successfully used to detect polyols in urinary samples from healthy subjects and diabetes patients, demonstrating accurate and reliable results. This method has potential applications in the recognition of inborn errors affecting polyol metabolism.

Quantum electronic stress: density-functional-theory formulation and physical manifestation

The concept of quantum electronic stress (QES) is introduced and formulated within density functional theory to elucidate extrinsic electronic effects on the stress state of solids and thin films in the absence of lattice strain. A formal expression of QES (σ(QE)) is derived in relation to deformation potential of electronic states (Ξ) and variation of electron density (Δn), σ(QE) = ΞΔn as a quantum analog of classical Hooke's law. Two distinct QES manifestations are demonstrated quantitatively by density functional theory calculations: (1) in the form of bulk stress induced by charge carriers and (2) in the form of surface stress induced by quantum confinement. Implications of QES in some physical phenomena are discussed to underlie its importance.

Fractal Landau-level spectra in twisted bilayer graphene

The Hofstadter butterfly spectrum for Landau levels in a two-dimensional periodic lattice is a rare example exhibiting fractal properties in a truly quantum system. However, the observation of this physical phenomenon in a conventional material will require a magnetic field strength several orders of magnitude larger than what can be produced in a modern laboratory. It turns out that for a specific range of rotational angles twisted bilayer graphene serves as a special system with a fractal energy spectrum under laboratory accessible magnetic field strengths. This unique feature arises from an intriguing electronic structure induced by the interlayer coupling. Using a recursive tight-binding method, we systematically map out the spectra of these Landau levels as a function of the rotational angle. Our results give a complete description of LLs in twisted bilayer graphene for both commensurate and incommensurate rotational angles and provide quantitative predictions of magnetic field strengths for observing the fractal spectra in these graphene systems.

Spatial and energy distribution of topological edge states in single Bi(111) bilayer

By combining scanning tunneling microscopy and spectroscopy, angle-resolved photoemission spectroscopy, and density functional theory band calculations, we directly observe and resolve the one-dimensional edge states of single bilayer (BL) Bi(111) islands on clean Bi(2)Te(3) and Bi(111)-covered Bi(2)Te(3) substrates. The edge states are localized in the vicinity of step edges having an ∼2  nm wide spatial distribution in real space and reside in the energy gap of the Bi(111) BL. Our results demonstrate the existence of nontrivial topological edge states of single Bi(111) bilayer as a two-dimensional topological insulator.

[Study on dioxin emission for typical non-wood pulp making in China]

Based on the requirement of National Implementation Plan for the Stockholm Convention on Persistent Organic Pollutants (NIP), six industries including pulp and paper industry have been set as the priority key sectors to implement the best available technology and best environmental practice (BAT/BEP) within a specific time for UPOPs reduction. Non-wood pulping has always played important role in virgin pulp production in China, its elemental chlorinated bleaching process has been confirmed as main source of Dioxin emission for the sector. As the signature party of Stockholm Convention and long time existing country of non-wood pulping, identification of Dioxin emission situation is significant importance to China to committee the obligation of Stockholm Convention. The Dioxin concentrations in outflow water of bamboo, straw, reed, and bagasse pulping processes (chlorination alkaline extraction hypochlorite, CEH) are 41.8 pg x L(-1), 72.7 pg x L(-1), 7.46 pg x L(-1), and 19.7 pg x L(-1) respectively, which are all around the national waste water discharge standard (30 pg x L(-1)). But relevant data will easily exceed national standard while the limitation of unit water consumption for pulp making is decreased. So the application of best available techniques/best environmental practices (BAT/BEP) is very necessary to improve relevant mills up to the above standard, and proceed the sector meeting the national and international requirements for Dioxin emission. At the same time, the text calculates emission factors on bamboo, straw, reed and bagasse pulp making process through whole process monitoring, which will provide meaningful reference for increasing relevant factors in UNEP Toolkit.

Converting steady laminar flow to oscillatory flow through a hydroelasticity approach at microscales

We report a hydroelasticity-based microfluidic oscillator that converts otherwise steady laminar flow to oscillatory flow. It incorporates an elastic diaphragm to enhance nonlinearity of the flow. Negative differential flow resistance is observed. High-frequency oscillatory flow is produced passively through interactions among hydrodynamic, elastic and inertial forces, without resorting to external actuators and control equipment. Driven by fluid flow and pressure, this device can operate in either steady laminar flow or oscillatory flow states, or work as a valve. Its applications for flow control and operation, and mixing enhancement are demonstrated.

Nanopatterned graphene quantum dots as building blocks for quantum cellular automata

Quantum cellular automata (QCA) is an innovative approach that incorporates quantum entities in classical computation processes. Binary information is encoded in different charge states of the QCA cells and transmitted by the inter-cell Coulomb interaction. Despite the promise of QCA, however, it remains a challenge to identify suitable building blocks for the construction of QCA. Graphene has recently attracted considerable attention owing to its remarkable electronic properties. The planar structure makes it feasible to pattern the whole device architecture in one sheet, compatible with the existing electronics technology. Here, we demonstrate theoretically a new QCA architecture built upon nanopatterned graphene quantum dots (GQDs). Using the tight-binding model, we determine the phenomenological cell parameters and cell-cell response functions of the GQD-QCA to characterize its performance. Furthermore, a GQD-QCA architecture is designed to demonstrate the functionalities of a fundamental majority gate. Our results show great potential in manufacturing high-density ultrafast QCA devices from a single nanopatterned graphene sheet.

Design and syntheses of novel N-(benzothiazol-5-yl)-4,5,6,7-tetrahydro-1H-isoindole-1,3(2H)-dione and N-(benzothiazol-5-yl)isoindoline-1,3-dione as potent protoporphyrinogen oxidase inhibitors

Discovery of protoporphyrinogen oxidase (PPO, EC 1.3.3.4) inhibitors has been one of the hottest research areas in the field of herbicide development for many years. As a continuation of our research work on the development of new PPO-inhibiting herbicides, a series of novel N-(benzothiazol-5-yl)-4,5,6,7-tetrahydro-1H-isoindole-1,3(2H)-diones (1a-p) and N-(benzothiazol-5-yl)isoindoline-1,3-diones (2a-h) were designed and synthesized according to the ring-closing strategy of two ortho-substituents. The bioassay results indicated that some newly synthesized compounds exhibited higher PPO inhibition activity than the control of sulfentrazone. Compound 1a, S-(5-(1,3-dioxo-4,5,6,7-tetrahydro-1H-isoindol-2(3H)-yl)-6-fluorobenzothiazol-2-yl) O-methyl carbonothioate, was identified as the most potent inhibitor with k(i) value of 0.08 μM, about 9 times higher than that of sulfentrazone (k(i) = 0.72 μM). Further green house assay showed that compound 1b, methyl 2-((5-(1,3-dioxo-4,5,6,7-tetrahydro-1H-isoindol-2(3H)-yl)-6-fluorobenzothiazol-2-yl)thio)acetate, exhibited herbicidal activity comparable to that of sulfentrazone even at a concentration of 37.5 g ai/ha. In addition, among six tested crops, wheat exhibited high tolerance to compound 1b even at a dosage of 300 g ai/ha. These results indicated that compound 1b might have the potential to be developed as a new herbicide for weed control of wheat field.

Arsenite-induced apoptosis is prevented by selenite in A375 cell line

Arsenic trioxide induces apoptosis and clinical remission in patients diagnosed with acute promyelocytic leukemia. The human malignant melanoma A375 cells were treated with NaAsO2 (0.1–130 μM) and also treated with combined 10 μM NaAsO2 and 10 μM Na2SeO3. NaAsO2 arrested cell growth in the G1 phase and induced apoptosis in a concentration- and time-dependent manner. In contrast, administration of Na2SeO3 antagonized the cell growth inhibition and apoptosis induced by NaAsO2. The NaAsO2 treatment resulted in a marked increase in p53 protein as early as 4 h and in Bcl-2 protein level by 12 h. In addition, p53 downregulation accompanied the combined treatment of NaAsO2 and Na2SeO3. Thus, our results indicate upregulation of p53 and Bcl-2 play acrucial role in the NaAsO2-induced G1 arrest and apoptosis of A375 cells and that downregulation p53 appears to contribute to the inhibition by Na2SeO3 of the effects induced by NaAsO2.

Atomic layers of hybridized boron nitride and graphene domains

Two-dimensional materials, such as graphene and monolayer hexagonal BN (h-BN), are attractive for demonstrating fundamental physics in materials and potential applications in next-generation electronics. Atomic sheets containing hybridized bonds involving elements B, N and C over wide compositional ranges could result in new materials with properties complementary to those of graphene and h-BN, enabling a rich variety of electronic structures, properties and applications. Here we report the synthesis and characterization of large-area atomic layers of h-BNC material, consisting of hybridized, randomly distributed domains of h-BN and C phases with compositions ranging from pure BN to pure graphene. Our studies reveal that their structural features and bandgap are distinct from those of graphene, doped graphene and h-BN. This new form of hybrid h-BNC material enables the development of bandgap-engineered applications in electronics and optics and properties that are distinct from those of graphene and h-BN.

Design, synthesis, and 3D-QSAR analysis of novel 1,3,4-oxadiazol-2(3H)-ones as protoporphyrinogen oxidase inhibitors

Protoporphyrinogen oxidase (PPO, EC 1.3.3.4) has been identified as one of the most significant action targets for a large chemically diverse family of herbicides that exhibit some interesting characteristics, such as low use rate, low toxicity to mammals, and low environmental impact. As a continuation of research work on the development of new PPO inhibitors, some benzothiazole analogues of oxadiargyl, an important PPO-inhibiting commercial herbicide, were designed and synthesized by ring-closing of the substituents at the C-4 and C-5 positions. The bioassay results indicated that the series 8, 9, and 10 have good PPO inhibition activity with k(i) values ranging from 0.25 to 18.63 microM. Most interestingly, 9l, ethyl 2-((5-(5-tert-butyl-2-oxo-1,3,4-oxadiazol-2(3H)-yl)-6-fluorobenzothiazol-2-yl)sulfanyl) propanoate, was identified as the most promising candidate due to its high PPO inhibition effect (k(i) = 1.42 microM) and broad spectrum postemergence herbicidal activity at the concentration of 37.5 g of ai/ha.

A tunable quantum-dot device based on cross-bar graphene nanoribbon structures

In this paper, we present a tunable quantum-dot nanoelectronic device built upon a patterned graphene nanoribbon (GNR) cross-bar structure. The cross junction can confine electronic states with applied gate voltages. By varying the length and width of the cross junction, we can alter the spatial confinement and the number of discrete levels within the junction. In addition, quantum dots can be trapped in the cross junction regardless of the irregularities along the graphene edges. In this design, each cross junction is a basic device element. By applying controllable gate voltages perpendicular to the ribbon, we can tune cross junction in 'on' or 'off' state, which corresponds to the existence or absence of quantum dots. This design can also be used to make a random access memory (RAM) array.

First Report of Choke Disease Caused by Epichloë typhina on Orchardgrass (Dactylis glomerata) in China

Orchardgrass or cocksfoot (Dactylis glomerata L.) has been widely cultivated as a forage crop in many provinces of China (1). It is also a native perennial forage grass, which grows at the edge of forests, shrubs, and mountainous grasslands in Xinjiang and Sichuan (2). In September of 2007, signs of choke disease on orchardgrass were observed in a native grassland under birch woodland near Altai City, Xinjiang, China. Stromata, which formed on culms of diseased grass, enclosing the inflorescence and leaf sheath, were 4.5 to 5.5 mm long, smooth or wrinkled, white and later becoming yellowish or yellow, tuberculate, dry, and covered with perithecia. Inflorescences surrounded by fungal stromata were choked and failed to mature, thus restricting seed production. Pure cultures were obtained by directly scraping stromata from the surface and incubating it on antibiotic potato dextrose agar (PDA). The colonies were cottony, white on the upper surface, and white to yellow on the reverse. The growth rate was 13 to 21 mm per week at 25°C on PDA. Conidia were hyaline, lunate to reniform, and measured 4.1 ± 0.5 × 2.2 ± 0.5 μm. They accumulated in small globose heads at the tips of conidiogenous cells and were produced singly on conidiophores of 13 to 33 μm long and 2.7 to 4.1 μm wide at the base. Internal transcribed spacer (ITS) sequence by BLAST search had 99% similarity with an Epichloë typhina isolate of orchardgrass in Spain (GenBank Accession No. AM262420.1). Cultural characteristics, microscopic examination, and phylogenetic analysis showed that this choke disease on D. glomerata was caused by the fungus E. typhina (Pers.) Tul. & C. Tul. as described by White (4). To our knowledge, this is the first report of E. typhina causing choke disease on orchardgrass in China. The pathogen has been identified in France, England, Germany, Sweden, Switzerland, and the United States (3,4) with the same symptoms as those reported here. In 1997, choke disease was found in 70% of the fields in the Willamette Valley of Oregon, with disease incidences ranging from 0.05 to 28%. It was predicted to increase and spread under the prevailing climatic conditions (3). This new disease report is to provide observational and diagnostic information to help with recognition and prevention of disease spread in orchardgrass cultivation regions of China. References: (1) X. R. Chao et al. Shandong Agric. Sci. 1:7, 2005. (2) S. X. Jia, ed. China Forage Plant Flora. China Agriculture Press, Beijing, 1987. (3) W. F. Pfender and S. C. Alderman. Plant Dis. 83:754, 1999. (4) J. W. White. Mycologia 85:444, 1993.

The influence of recombinant human BMP-2 on bone-implant osseointegration: biomechanical testing and histomorphometric analysis

The healing period for bone-implant osseointegration lasts 3-6 months or even longer. The aim of this study was to investigate whether osseointegration can be enhanced by the use of bone morphogenetic protein-2 (BMP-2). In the femurs of 8 Japanese white rabbits, 16 implants were applied with 1.0 mg recombinant human BMP-2 (rhBMP-2) as group A, and the other 16 implants without rhBMP-2 as group B. Calcein green 20 mg/kg and alizarin red 20 mg/kg were injected 4 and 8 weeks after implantation, respectively. At 12 weeks, the animals were killed. In 16 implant-bone blocks, binding strength was measured by pull-out test, and the extracted implants were observed under a scanning electronic microscope. The other blocks were analysed for percentage of marked bone adjacent to the implant surface by confocal laser scanning microscope. The pull-out strengths of group A were greater than that of group B (P<0.05). Scanning electronic microscopy (SEM) showed more calcified substances on the surface of the implants of group A than B. There was more marked bone around group A than B implants at 4 weeks (P<0.05) and 8 weeks (P<0.05). rhBMP-2 improves the quantity and quality of implant-bone osseointegration. Biomechanical testing and histomorphometric analysis are reliable methods to use in researching the implant-bone interface.

Double spectral theorem and two type magnitude-squared coherence functions

Studying frequency domain representation for the coherence between two signals is an important basic theoretical problem in the fundamental theories of signal processing. However, the old magnitude-squared coherence function (OMSCF) has been proved identical to 1, so that to cannot be used to extract any coherence information. Here, we will prove a core theorem in frequency domain coherence theories in signal processing, called as the double spectral theorem (DST). Based on the theorem, we presented the two types of new magnitude-squared coherence functions (MSCFs), called as the same type magnitude-squared coherence function (SMSCF) and the difference magnitude-squared coherence function (DMSCF) respectively, which were mathematically derived from DST and the conditions that they are equal to 1 or 0 can be theoretically derived from DST. Here, we further demonstrated that SMSCF and DMSCF could be used to exactly extract the coherence between two signals by each component.

The new magnitude-squared coherence functions and their properties sensitive to phase

Based on the core theorem of the frequency domain coherence in signal processing, called as double spectral theorem, we presented the two types of new magnitude-squared coherence function (MSCFs) in order to extract the coherence between two signals and gave the conditions that they are equal to 1 or 0. Here, we further studied their properties sensitive to initial phases of two signals and phase difference between two signals. Studying demonstrated that the two type MSCFs not only reflect frequency domain coherence of two signals, but also reflect phase relationship between two signals. One is sensitive to the phase difference between two signals and the other is either sensitive to the initial phases or phase difference between two signals. We call the properties as their properties sensitive to phase.

Combinational synthesis of oligonucleotides and assembly fabrication of oligonucleotide array

In this paper, a simple, reliable and flexible method, which integrated in situ synthesis with the spotting technique, was reported to fabricate oligonucleotide array. Different oligonucleotide sequences are synthesized on their relative code glass slides through combinational chemistry, thus the slides are broken into smaller pieces, in which the same code pieces have the same probe sequences. An oligonucleotide array is fabricated by arbitrarily assembling these different code pieces onto another solid substrate. In principle experimentation, four different sequences of P16 gene were synthesized and a 5 x 5 array including these four sequences and the control black was fabricated. The analysis results indicated that the hybridization fluorescence intensity of the same sequences locating different sets on the array gave the approximate values, and the fluorescence intensity ratio of matched sequence to one middle location base mismatched, two base mismatched, three middle base mismatched is (1.000+/-0.080):(0.4991+/-0.0671):(0.2360+/-0.0044):(0.0493+/-0.0033). Their relative accuracies were from 6.64 to 10.2%. This result might be used to rapidly screen single-nucleotide polymorphisms (SNPs).

Intraurethral brachytherapy for prevention of recurrent urethral stricture after internal urethrotomy or transurethral resection of scar

BACKGROUND PURPOSE

Restricture after internal urethrotomy is the major limitation to the long-term success of the procedure. The objective of this study was to evaluate the effect of intraurethral brachytherapy after internal urethrotomy or transurethral scar resection on recurrent urethral stricture.

PATIENTS AND METHODS

From January 1998 to June 1999, catheter-based intraurethral brachytherapy with 192-iridium was performed in 17 patients with recurrent urethral stricture to prevent restricture after internal urethrotomy or transurethral resection of scar. The radiation was repeated within 3 days after surgery to reach a total dosage of 1000 to 1500 cGy.

RESULTS

During the follow-up (range 14-27 months; mean 20 months), two patients had dysuria, including one patient with an atonic detrusor muscle. The other patient needed self-dilation. Fifteen patients presented normal voiding. The stricture recurred 3 months later in only one patient, so the restricture rate is 7%. No significant complication was observed associated with brachytherapy during the follow-up.

CONCLUSION

Intraurethral brachytherapy after internal urethrotomy or transurethral resection of scar is a safe and effective treatment for recurrent urethral strictures.

[Physico-chemical properties and activity of glycoconjugate LbGp2 from Lycium barbarum L]

AIM

To isolate and purify a glycoconjugate (LbGp2) from the fruit of Lycium barbarum L. and study its immunoactivity and antioxidative activity.

METHODS

By means of gel permeation chromatography, LbGp2 was purified. Based on HPLC, CE, GC, SEC and component analysis and so on, its physico-chemical properties were studied.

RESULTS

Molecular weights of LbGp2 was 68.2 ku and its carbohydrate content was up to 90.7%. Component analysis showed that it composed of Ara and Gal in a molar ratio of 3:4, and 18 kinds of amino acids. The immunologic function and bioactivity of Lbp2 has been studied preliminarily. Lbp2 was shown to increase rate of phagocyticaction and phagocytic index, promote lymphocyte translation and accelerate the production of serum hemolysin. LbGp2 has distinct effect of antioxidation and the superoxide anion produced by DMSO-NaOH system was scavenged effectively.

CONCLUSION

LbGp2 was shown to be a kind of homogeneous glycoconjugate with good immunoactivity and antioxidative activity.

[Hemorrhagic shock induces changes in large-conductance Ca(2+) dependent K+ channel activity in mesenteric arterial smooth muscle cells of rats]

The purpose of the present study was to detect changes in the activity of large-conductance Ca(2+)activated K(+) channel (BK(Ca)) during hemorrhagic shock (HS) in mesenteric arterial vascular smooth muscle cells using inside-out patches. The HS rat model was produced with withdrawing blood from the femoral artery. The results showed that the BK(Ca) activity was inhibited with decreased open probability (P(o)) and single-channel conductance. The decrease of P(o) resulted from an increase of the close time constant (tau(cs)) in the compensatory stage of HS, i.e.the term of hyperresponse of the muscle to norepinephrine (NE) (HS lasted for about 40 min). During the decompensation stage of HS, i.e. the period of hyporesponse to NE (HS developed for 3 h), the BK(Ca) activity was enhanced with the increase in single-channel conductance and P(o) which was a result of a decrease in tau(cs).

Inhibition of large-conductance Ca(2+)-activated K(+) channels in hippocampal neurons by toosendanin

The effect of toosendanin, a selective presynaptic blocker and effective antibotulismic agent, on large-conductance Ca(2+)-activated K(+) channels was studied in inside-out patches of pyramidal neurons freshly isolated from the hippocampal CA1 region of the rat. Toosendanin (1 x 10(-6)g/ml approximately 1 x 10(-4)g/ml) was found to inhibit large-conductance Ca(2+)-activated K(+) channels by reducing its open probability significantly in a concentration-dependent manner, although the effective concentration of toosendanin was lower in a symmetrical K(+) (150 mM) solution than under asymmetrical conditions (changing K(+) concentration in pipette solution to 5mM). The action was partially reversible by washing. By decreasing the slow open time constant, toosendanin shortened the open dwell time of large-conductance Ca(2+)-activated K(+) channels in a dose-dependent manner. A dose-dependent reduction of unitary current amplitude of the channel was detected after toosendanin perfusion. On elevating the intracellular free calcium concentration from 1 to 10 microM, a similar effect on large-conductance Ca(2+)-activated K(+) channels by toosendanin was also observed, but its efficacy was diminished. These results show that toosendanin inhibits large-conductance Ca(2+)-activated K(+) channels in hippocampal neurons by reducing the open probability and unitary current amplitude of the channel, and that Ca(2+) interferes with the effect. These data provide an explanation for toosendanin-induced facilitation of neurotransmitter release and the antibotulismic effect of the drug.

Modulation of inward rectifier potassium channel by toosendanin, a presynaptic blocker

The effect of toosendanin, a presynaptic blocker, on the inward rectifier potassium channel (K(Kir)) of hippocampal CA1 pyramidal neurons of rats was studied by the single-channel patch-clamp technique. The results showed that toosendanin had an inhibitory effect on K(Kir) in an excised inside-out patch of the neuron under a symmetrical 150 mM K(+) condition. By decreasing the slower open time constant and increasing the slower close time constant, toosendanin (1x10(-6)-1x10(-4) g/ml) significantly reduced the open probability of the channel in a concentration-dependent manner. Meanwhile, a dose-dependent reduction in unitary conductance of the channel was also detected after toosendanin application. These data offer an explanation for toosendanin-induced facilitation of neurotransmitter release and antibotulismic effect of the drug.