Effect of transport agent boron triiodide on the synthesis and crystal quality of boron arsenide

Cubic boron arsenide(BAs)has attracted great attention due to its high thermal conductivity,however,its controllable,stable,and ideal preparation remains challenging.Herein,we investigated the effect of iodine-containing transport agents I_(2) and boron triiodide(BI_(3))on BAs synthesized and grown through chemical vapor transport.Results show that similar to the commonly used I_(2),BI_(3) accelerates the synthesis and improves the mass fraction of BAs from ~12% to over 90% at 820℃ and 1.5 MPa,a value beyond the promoting effect of only increasing temperature and pressure.Both agents enhance the quality of BAs crystals by reducing the full width at half maximum by up to 10%-20%.I_(2) agglomerates the grown crystals with twin defects(~50 nm wide),and BI_(3) improves the crystal anisotropy and element uniformity of BAs crystals with narrow twins(~15 nm wide)and increases the stoichiometry ratio(~0.990)to almost 1.Owing to the boron interstitials from the excessive boron supply,the spacing of layers in {111} increases to 0.286 nm in the presence of I_(2).Owing to its coordinated effect,BI_(3) only slightly influences the layer spacing at 0.275 nm,which is close to the theoretical value of 0.276 nm.In the chemical vapor transport,the anisotropic crystals with flat surfaces exhibit single-crystal characteristics under the action of BI_(3).Different from that of I_(2),the coordinated effect of BI_(3) can promote the efficient preparation of high-quality BAs crystal seeds and facilitate the advanced application of BAs.

Understanding of impact of carbon doping on background carrier conduction in GaN

The impact of carbon doping on the background carrier conduction in GaN has been investigated.It is found that the incorporation of carbon can effectively suppress the n-type background carrier concentration as expected.Moreover,from the fitting of the temperature-dependent carrier concentration and mobility,it is observed that high nitrogen-vacancy(VN)dominates the background carrier at room temperature which consequently results in n-type conduction.The doping agent(carbon atom)occupies the nitrogen site of GaN and forms CN deep acceptor as revealed from photoluminescence.Besides,a relatively low hole concentration is ionized at room temperature which was insufficient for the compensation of n-type background carriers.Therefore,we concluded that this background carrier concentration can be suppressed by carbon doping,which substitutes the N site of GaN and finally decreases the VN.

Analyses on the Overall Codon Usage Pattern in Fish Rhabdovirus

The codon usage bias and the base compositions in the available 49 complete fish rhabdovirus genome sequences were investigated. The high correlation between GC12% and GC3% suggested that mutational pressure rather than natural selection was the main factor determining the codon usage and base component in fish rhabdovirns, most of the spots lying below the expected curve （ ENC vs GC3% ） also suggested that codon usage bias in these 49 genomes was influenced by mutational pressure in codon usage pattern. Through PCA analysis based on RSCU, all ORFs in the 49 fish rhabdoviurs genomes were clustered into two parts, and this result showed that hosts played a role in codon usage pattern of fish rhabdovirns genomes. Further, comparison between SVCV, INHV, VHSV and their hosts suggested the effect of natural host on the codon usage pattern took part in the evolution process of fish rhabdovirns. This study represents the most comprehensive analysis to date for fish rhabdovirus eodon usage patterns.

Increased N6-methyladenosine is related to the promotion of the methyltransferase METTL14 in ovarian aging

The ovary is a vital female reproductive organ that functions to produce oocyte gametes and cyclically expressed sex hormones to maintain reproductive capacity and hormone homeostasis.Ovarian aging,characterized by declines in follicle quantity and oocyte quality,leads to premature ovarian failure,premature ovarian insufficiency,or diminished ovarian reserve,thus contributing to female infertility.Distinct gene-expression signatures from RNA transcriptional level and post-transcriptional regulation are relative to oocyte quality and reproductive age.

Geochemical characteristics of produced fluids from CBM wells and their indicative significance for gas accumulation in Daning-Jixian block,Ordos Basin

The Daning-Jixian block,the eastern edge of the Ordos Basin,is one of the most potential areas for CO_(2)geological storage,enhanced coalbed methane recovery(ECBM)exploration and production in China in recent decades.The ionic composition and total dissolved solids(TDS)of the produced water,coal organic matter maturity,molecular composition and carbon isotope characteristics of the produced gas were utilized to analyze the hydrogeological condition,CBM generation and migration characteristics in this area.The CBM enrichment patterns and the geological impacts on gas well production characteristics were revealed.The optimal area for CBM development and CO_(2)geological storage in the study area were also proposed.Dominated by the Xueguan reverse fault zone,the hydraulic unit in this area can be divided into two parts(i.e.,the recharge-runoff zone in the east and the weak runoff-stagnation zone in the west).The thermogenic gas is dominating CBM genesis in this area.Secondary biogenic gas replenishment is only distributed in the eastern margin area,where theδ13C1 value is less than the thermal simulation results as an influence of hydrodynamic fractionation.Finally,two models of CBM formation and accumulation were proposed,1)thermogenic CBM migrated by hydrodynamic and resorbed for preservation at impermeable fault boundaries;2)thermogenic CBM trapped by fault and accumulated by hydrodynamic in slope zone.The gas production performance,generally increased from east to west,is mainly dominated by hydrogeological conditions.Generally,the west side of the fault zone is the enrichment and high-yield area for ECBM development and CO_(2)geological storage in the study area.

Transition-metal-free coupling reactions involving gem–diborylalkanes

Due to the increasing demand for the sustainability of modern organic chemistry, the development of green and powerful methods for C-C and C-B bond formation is highly desired. Among them, the transition-metal-free coupling reactions of gem–diborylalkanes emerge as one valuable tool for organic chemists in the last decade. The review covers selected representative examples. A comparison of these reactions with transition-metal-catalyzed reactions is provided. The recent example of α-boryl radical formation from gem–diborylalkanes is also briefly discussed.

Type I photosensitizer based on AIE chromophore tricyano-methylene-pyridine for photodynamic therapy

Image guided photodynamic therapy(PDT)combines fluorescence tracing and phototherapy,which can achieve a more accurate and effective treatment effect.However,traditional photosensitizers are limited by the aggregation-caused fluorescence quenching(ACQ)effect and low reactive oxygen species(ROS)generation in a hypoxic environment,resulting in poor imaging and treatment effect.Herein,we report a tricyano-methylene-pyridine(TCM)-based Type I aggregation-induced emission(AIE)photosensitizer(TCM-MBP),the strong elec-tron acceptance(D-A)effect extends the wavelength to near-infrared(NIR)region to reduce the autofluorescence interference,and oxygen atoms provide lone pair electrons to enhance the inter system crossing(ISC)rate,thereby promoting the generation of more triplet states to produce ROS.The AIE photosensitizer TCM-MBP exhibited low oxygen dependence,NIR emission,and higher ROS production compared to commercially avail-able Ce_(6) and RB.After encapsulation with DSPE-PEG 2000,TCM-MBP nanoparticles(TCM-MBP NPs)could penetrate to visualize cells and efficiently kill cancer cells upon light irradiation.This study provides an oxygen-independent AIE photosensitizer,which has great potential to replace the commercial ACQ photosensitizers.

Generation of arbitrary vector vortex beams on hybrid-order Poincaré sphere

We propose theoretically and verify experimentally a method of combining a q-plate and a spiral phase plate to generate arbitrary vector vortex beams on a hybrid-order Poincaré sphere. We demonstrate that a vector vortex beam can be decomposed into a vector beam and a vortex, whereby the generation can be realized by sequentially using a q-plate and a spiral phase plate. The generated vector beam, vortex, and vector vortex beam are verified and show good agreement with the prediction. Another advantage that should be pointed out is that the spiral phase plate and q-plate are both fabricated on silica substrates, suggesting the potential possibility to integrate the two structures on a single plate. Based on a compact method of transmissive-type transformation, our scheme may have potential applications in future integrated optical devices.

Weak-value amplification for the optical signature of topological phase transitions

We show that weak measurements can be used to measure the tiny signature of topological phase transitions.The signature is an in-plane photonic spin Hall effect,which can be described as a consequence of a Berry phase.It is also parallel to the propagation direction of a light beam.The imaginary part of the weak value can be used to analyze ultrasmall longitudinal phase shifts in different topological phases.These optical signatures are related to the Chern number and bandgaps;we also use a preselection and postselection technique on the spin state to enhance the original signature.The weak amplification technique offers a potential way to determine the spin and valley properties of charge carriers,Chern numbers,and topological phases by direct optical measurement.

A facile access to mono-C-alkynylated-o-carboranes from o-carboranes and arylsulfonylacetylenes

A facile access to mono-C-alkynyl-o-carboranes from o-carboranes and arylsulfonylacetylenes was developed.This facile process tolerates a wide variety of functional groups,occurs at mild conditions in onepot procedure with short reaction time.The obtained mono-C-alkynyl-o-carboranes can be easily derivatized to synthesize 1,2-difunctionalized o-carboranes.This work provides a useful tool for the functionalization of o-carboranes.

Palladium（o）-Catalyzed Si-Si Bond Insertion by the Terminal Nitrogen of Diazo Compoundst

The palladium（o）-catalyzed nitrogen insertion into cyclic Si-Si bonds has been realized by using N-tosylhydrazones/diazo compounds as the nitrogen source. The palladium（Ⅱ） nitrene formation and subsequent migratory insertion process are proposed as the key steps for this reaction.

Release of Pb adsorbed on graphene oxide surfaces under conditions of Shewanella putrefaciens metabolism

In this study, Pb(Ⅱ) was used as a target heavy metal pollutant, and the metabolism of Shewanella putrefaciens(S. putrefaciens) was applied to achieve reducing conditions to study the effect of microbial reduction on lead that was preadsorbed on graphene oxide(GO) surfaces.The results showed that GO was transformed to its reduced form(r-GO) by bacteria, and this process induced the release of Pb(Ⅱ) adsorbed on the GO surfaces. After 72 hr of exposure in an S. putrefaciens system, 5.76% of the total adsorbed Pb(Ⅱ) was stably dispersed in solution in the form of a Pb(Ⅱ)-extracellular polymer substance(EPS) complex, while another portion of Pb(Ⅱ) released from GO-Pb(Ⅱ) was observed as lead phosphate hydroxide(Pb_(10)(PO_(4))_(6)(OH)_(2))precipitates or adsorbed species on the surface of the cell. Additionally, increasing pH induced the stripping of oxidative debris(OD) and elevated the content of dispersible Pb(Ⅱ)in aqueous solution under the conditions of S. putrefaciens metabolism. These research results provide valuable information regarding the migration of heavy metals adsorbed on GO under reducing conditions due to microbial metabolism.

Catalyst-free reductions of nitriles to amino-boranes using sodium amidoborane and lithiumborohydride

An efficient and facile method to reduce nitriles to amine-boranes was developed.Aromatic and aliphatic nitriles were readily reduced in the presence of both sodium amidoborane(NaAB)and LiBH4 at room temperature in THF without catalysts,affording products in up to 99%yield.The products can be easily hydrolyzed to afford primary amines or utilized as reducing reagents for one-pot reductive amination.The key finding of the reaction study is the synergy effect between NaAB and LiBH4;otherwise the reaction yield would drop substantially from 92%to 22%or 12%when NaAB and LiBH4 are used separately.

Spatiotemporal Visualization of Cell Membrane with Amphiphilic Aggregation-Induced Emission-Active Sensor

High-fidelity spatiotemporal monitoring of the cell membrane is critically important.However,commercial fluorescence probes are stalked by the aggregation-caused quenching(ACQ)effect,and the reported aggregation-induced emission(AIE)-active probes are always limited by nonspecific aggregations in the biological environment.Herein,we report the rational molecular design of a stateof-the-art amphiphilic AIE luminogen(AIEgen),membrane tracker QMC12,using a core quinolinemalononitrile(QM)structure to suppress the ACQ effect,incorporate a positively charged pyridinium to regulate dispersity and strengthen the binding affinity to the negatively charged cell membrane,and extend the alky chain to improve the anchoring ability to the cell membrane.The membrane tracker QMC12,which disperses well in both hydrophilic and lipophilic environments,not only achieves minimal background interference and high signal-to-noise(S/N)ratio in the“ultrafast”visualization of the cell membrane,but also endows a“wash-free”characteristic.Furthermore,it realizes a spatial three dimensional(3D)view in a multicellular spheroid model and morphology changes over time.Moreover,QMC12 avoids false staining and signal loss and unprecedentedly achieves the direct observation of the cell membrane’s microstructure,which could elucidate spatiotemporal 3D model studies of the intercellular information exchange.

An AIE-based enzyme-activatable fluorescence indicator for Western blot assay:Quantitative expression of proteins with reproducible stable signal and wide linear range

Western blot is a commonly used experimental method to analyze the protein expression.However,the most commonly used chromogenic indicator based on chemiluminescence is limited by narrow linear range and unstable quantitative reproducibility,whereas the recently developed fluorescent indicator suffers from poor detection limit.Herein,we report an enzyme-activatable fluorescence indicator to quantify proteins with reproducible stable signal and wide linear range,through introducing the hydrophilic alkaline phosphatase(ALP)-triggered phosphoric acid moiety into our established aggregation-induced emission(AIE)building block of quinoline-malononitrile(QM).In this strategy,the indicator DQM-ALP disperses well in both aqueous and lipid environments to exhibit initial“off”fluorescence,but when exposing to the ALP-coupled secondary antibody on the PVDF membrane,the specific enzymatic turnover would liberate hydrophobic AIE luminogen(AIEgen)QM-OH to emit strong luminescence,thereby achieving an ideal“off-on”state for sensitively imaging proteins with high signal-to-noise(S/N)ratio.Moreover,benefiting from the excellent signal stability of AIE fluorophore,DQM-ALP indicator exhibits superior quantitative analysis of protein expression with high reproducibility.Upon taking advantage of the AIEgens to reduce high concentration-induced luminance quenching,the linear quantification range is extremely expanded.In contrast with the traditional chemiluminescent indicator,the AIE-based enzymeactivatable indicator DQM-ALP not only greatly improves the signal stability for quantitative reproducibility,but also expands the linear quantification range,and further provides a practical alternative reagent for fluorescence Western blot assay.