酰胺化反应制备聚(对苯二甲酰十二碳二元胺-共-对苯二甲酸乙二醇酯)共聚物

文中以十二碳二元胺(DDMD)和聚对苯二甲酸乙二醇酯(PET)为原料,环丁砜为溶剂,制备了聚(对苯二甲酰十二碳二元胺-共-对苯二甲酸乙二醇酯)(Poly(12T-co-ET))共聚物。考察了反应温度、投料比和溶剂用量对产物相对黏度和转化率的影响,确定其最佳工艺条件为,反应温度为210°C、DDMD与PET的投料摩尔比为1.1:1、PET与溶剂的质量比为1:10,得到产物的相对黏度为1.37、转化率为82.1%。通过傅里叶变换红外光谱和核磁共振氢谱确认了产物的结构。差示扫描量热分析和热失重分析结果表明,产物的熔点为234°C、结晶温度为201°C,初始热分解温度为357°C。拉伸强度为37.0 MPa、断裂伸长率为9.32%、弯曲强度为49.2 MPa、缺口冲击强度为1.5 kJ/m^(2)。动态力学热分析结果显示其玻璃化转变温度(T_(g))为91°C。尽管共聚物的综合性能较差,但仍可以作为基体树脂进行共混改性使用,同时,该聚合方法对PET的回收和环境保护具有一定的实用价值。

A Projection and Contraction Method for P-Order Cone Constraint Stochastic Variational Inequality Problem

In this paper, we study the p-order cone constraint stochastic variational inequality problem. We first take the sample average approximation method to deal with the expectation and gain an approximation problem, further the rationality is given. When the underlying function is Lipschitz continuous, we acquire a projection and contraction algorithm to solve the approximation problem. In the end, the method is applied to some numerical experiments and the effectiveness of the algorithm is verified.

通过式固相萃取-UPLC-MS/MS法测定育发液中35种糖皮质激素

为了评估育发液中是否违法添加糖皮质激素,采用超高效液相色谱串联三重四极杆质谱(UPLC-MS/MS)建立了一种同时测定育发液中35种糖皮质激素的方法。样品加饱和氯化钠溶液分散,经乙腈提取,以PRiME HLB固相萃取柱净化,ACQUITY BEH C_(18)柱(1.7μm,2.1 mm×100 mm)分离,流动相A为含0.1%甲酸和2 mmol/L乙酸铵的水溶液,流动相B为含0.1%甲酸的乙腈溶液,进行梯度洗脱,多反应监测模式(MRM)进行检测,外标法定量。结果表明,35种糖皮质激素的色谱分离效果良好,在2~30 ng/mL范围内呈良好的线性关系,决定系数(R^(2))均大于0.99,方法检出限(LOD,S/N≥3)和定量限(LOQ,S/N≥10)分别在0.01~0.65μg/L和0.03~2.20μg/L之间,各加标水平的平均回收率在62.4%~92.9%之间,相对标准偏差(RSD)为1.7%~5.7%。该方法同时检测育发液中35种糖皮质激素,可用于育发液质量安全的监控。

The biogenic silica variation and paleoproductivity evolution in the eastern Indian Ocean during the past 20 000 a

The biogenic silica of sediment samples from Core CJ01-185 which is collected from the eastern India Ocean off the Sunda Strait is analyzed to evaluate the impact of the opening of the Sunda Strait on a paleoproductivity evolution. The new results indicate that the biogenic silica mass values of Core CJ01-185 show the lowest 0.86% in the last glacial period, and reach its maxima of 1.89% in the late Holocene. Furthermore, the biogenic silica mass accumulation rate(MARBSi) values also vary with much higher during the late Holocene than during the last glaciation. The input of additional terrigenous materials from the Java Sea has enhanced the paleoproductivity and increased the biogenic silica mass and MARBSi values after the opening of the Sunda Strait. It is suggested that the paleoproductivity in the study area is mainly influenced by the southeast monsoon and upwelling before the opening of the Sunda Strait. However, the paleoproductivity is dominated by the terrigenous materials input other than by the southeast monsoon or upwelling in the Holocene.

Enhanced Catalytic Activity of Gold@Polydopamine Nanoreactors with Multi-compartment Structure Under NIR Irradiation

Photothermal conversion(PTC)nanostructures have great potential for applications in many fields,and therefore,they have attracted tremendous attention.However,the construction of a PTC nanoreactor with multi-compartment structure to achieve the combination of unique chemical properties and structural feature is still challenging due to the synthetic difficulties.Herein,we designed and synthesized a catalytically active,PTC gold(Au)@polydopamine(PDA)nanoreactor driven by infrared irradiation using assembled PS-b-P2VP nanosphere as soft template.The particles exhibit multi-compartment structure which is revealed by 3D electron tomography characterization technique.They feature permeable shells with tunable shell thickness.Full kinetics for the reduction reaction of 4-nitrophenol has been investigated using these particles as nanoreactors and compared with other reported systems.Notably,a remarkable acceleration of the catalytic reaction upon near-infrared irradiation is demonstrated,which reveals for the first time the importance of the synergistic effect of photothermal conversion and complex inner structure to the kinetics of the catalytic reduction.The ease of synthesis and fresh insights into catalysis will promote a new platform for novel nanoreactor studies.

Comparative transcriptome analysis of abalone Haliotis discus hannai with green and gray egg colors

Haliotis discus hannai is an important marine economic species in China.Its egg color was found to be associated with economic traits,which provides a new idea for breeding.However,the molecular mechanism of the egg-color formation has not been reported.Thus,the pigment composition and comparative transcriptome analyses of H.discus hannai with green and gray egg color were conducted using high-performance liquid chromatography(HPLC)and RNA-Seq methods.Results show that individuals with green and gray eggs both possess the fucoxanthin.Lutein existed in gray-egged individuals,but not in green-egged individuals.In transcriptome analysis,272310 unigenes were received from 461162 transcripts with a mean length of 985 bp and N50 of 1524 bp,respectively.A total of 185 unigenes were identifi ed as diff erentially expressed genes(DEGs).The DEGs involved in“fl avin-containing compound metabolic process”,“melanosome”,“glutathione metabolism”,and“cytochrome b6f complex”were likely related to the formation of the egg color.Our results provide foundational information for the functional analysis of egg-color related genes and are benefi cial to the selective breeding of H.discus hannai.

Isolation and identification of respiratory tract and intestinal microflora of Meriones meridianus in a conventional animal facility

Background: Culturable bacterial species from the respiratory tract and ileocecal junction of Meriones meridianus(midday gerbils) captured in the Xinjiang Luntai area were isolated and identified to confirm the microflora and develop approaches for biological purification of laboratory animals and relevant microbial precautions.Methods: Bacteria from respiratory tracts and ileocecal junctions of 30 wild M. meridianus were harvested and isolated by inoculation into culture media. Isolated strains were confirmed by mass spectrometry and 16 S rRNA sequencing.Results: Thirty-nine bacterial species from 20 families and 27 genera were identified and isolated from wild M. meridianus. Typical bacteria were Enterobacteriaceae,Enterococcus, and Staphylococcus aureus, and the most common microflora were Vibrio, Staphylococcus aureus, and Pseudomonas aeruginosa.Conclusion: Wild M. meridianus carries multiple bacteria, most of which are pathogenic or conditional pathogens. This study provides a basis for the development of animal models and laboratory animals from wild M. meridianus.

2D Ca/Nb-based perovskite oxide with Ta doping as highly efficient H_(2)O_(2)synthesis catalyst

Perovskite oxides(POs)are emerging as a class of highly efficient catalysts for reducing oxygen to H_(2)O.Although a rich variety of POs-based catalysts have been developed by tuning the complex composition,a highly efficient PO catalyst that is able to alter the reaction pathway from a 4e−process to a 2e−process for H_(2)O_(2)production has rarely been achieved.We modified the structure and composition of a Ca-and Nb-based PO material by realizing a uniform two-dimensional(2D)morphology and varied Ta doping,resulting in the 2D Ca_(2)Nb_(3−x)Ta_(x)O_(10)−(x=0,0.5,1,and 1.5)monolayer catalysts.The obtained catalysts exhibit a dominant 2e−pathway and show exceptional H_(2)O_(2)production efficiency.The typical Ca_(2)Nb_(2.5)Ta_(0.5)O_(10)−nanoflakes showed an onset potential of 0.735 V vs.reversible hydrogen electrode(RHE),a remarkably high selectivity over 95%across a wide range of 0.3-0.7 V,an impressively high Faradaic efficiency of 94%,and a notable H_(2)O_(2)productivity of 1571 mmol·gcat^(−1)·h^(−1).These findings highlight the great potential of 2D perovskite oxide nanoflakes as advanced electrocatalysts for 2e−oxygen reduction reaction.

Viologens-based redox mediators with tunable HOMO–LUMO energy gap for highly effective hydrogen peroxide electrosynthesis

In comparison with the developing nano-carbon catalysts,some small organic molecules are also emerging as catalysts with typical features,however,their working mechanism is still unclear.Here,we synthesized a series of viologen-based heterogeneous catalysts with the same molecular skeleton but different substituent groups through anion exchange engineering.These viologen-based molecules were used as a model catalyst to investigate the underlying structure–function relationship for small molecules-based H_(2)O_(2) electrosynthesis.Differing from the commonly reported carbon-based electrocatalysts,viologens can produce H_(2)O_(2) in a synergistic manner,which means that viologens can not only directly catalyze oxygen reduction but also serve as a redox mediator.We found that the ring current and H_(2)O_(2) selectivity of viologens deliver an increasing trend with the increase of the alkyl chain length of alkyl-substituted viologens and further increase when using benzyl as the substituent group.As a result,a benzyl-substituted viologen(BV)delivers the best electrocatalytic performance among the samples,including the highest H_(2)O_(2) selectivity of 96.9%at 0.6 V and the largest ring current density of about 13.6 mA·mmol-1.Furthermore,density functional theory(DFT)calculations disclose that the carbon atoms bonded with positively charged N are the active sites and the small highest occupied molecular orbital(HOMO)–lowest unoccupied molecular orbital(LUMO)energy gap of BV is beneficial to the synergistic mechanism for H_(2)O_(2) production.This work sheds new insight into the efficient H_(2)O_(2) production in a synergistic manner for small molecules-based electrocatalysts.

A non-two-dimensional van der Waals In Se semispherical array grown by vapor-liquid-solid method for hydrogen evolution

Two-dimensional(2D)layered materials with layer-number dependent properties are promising candidates for next-generation noble-metal-free electrocatalytic reaction.However,the main group metal chalcogenides(MMCs)used for this purpose are rarely explored.Herein,we report the controlled growth of indium selenide(In Se)with a novel morphology(semispherical array)on a silicon substrate and its application in hydrogen evolution reaction(HER).The formation of the spherical InSe is explained with a vapor-liquid-solid growth mechanism,in which the distribution and size of the spheres could be facilely tuned by the reaction parameters.The InSe semispherical array was demonstrated as more efficient catalyst for HER than the flake-like 2D InSe counterparts,originating from the fully exposed InSe spherical surface with abundant adsorbing sites and the high crystalline quality for electron transport.This work provides a controlled synthesis way of the layered In Se with a distinct spherical morphology used for the electrocatalysis applications and could be extended to other main group metal chalcogenides.

Extracellular vesicles derived from human dental mesenchymal stem cells stimulated with low-intensity pulsed ultrasound alleviate inflammation-induced bone loss in a mouse model of periodontitis

Extracellular vesicles(EVs)derived from mesenchymal stem cells(MSCs)have emerged as a new mode of intercellular crosstalk and are responsible for many of the thera-peutic effects of MSCs.To promote the application of MSC-EVs,recent studies have focused on the manipulation of MSCs to improve the production of EVs and EV-mediated activities.The current paper details an optimization method using non-invasive low-intensity pulsed ul-trasound(LIPUS)as the stimulation for improving oral MSC-EV production and effectiveness.Stem cells from apical papilla(SCAP),a type of oral mesenchymal stem cell,displayed inten-sity-dependent pro-osteogenic and anti-inflammatory responses to LIPUS without significant cytotoxicity or apoptosis.The stimuli increased the secretion of EVs by promoting the expres-sion of neutral sphingomyelinases in SCAP.In addition,EVs from LIPUS-induced SCAP exhibited stronger efficacy in promoting the osteogenic differentiation and anti-inflammation of peri-odontal ligament cells in vitro and alleviating oral inflammatory bone loss in vivo.In addition,LIPUS stimulation affected the physical characteristics and miRNA cargo of SCAP-EVs.Further investigations indicated that miR-935 is an important mediator of the pro-osteogenic and anti-inflammatory capabilities of LIPUS-induced SCAP-EVs.Taken together,these findings demonstrate that LIPUS is a simple and effective physical method to optimize SCAP-EV produc-tion and efficacy.

山东省低温暴露所致死亡风险的季节内差异分析

目的分析山东省低温暴露死亡风险的季节内差异。方法通过山东省疾病预防控制中心收集2013—2018年山东省的全人群死亡数据, 基本资料主要包括死亡日期、年龄、性别、受教育程度、死亡原因、家庭住址等;通过中国气象数据网同期逐日气象资料, 主要包括日平均温度(℃)、日平均相对湿度(%)等0.01°×0.01°经纬度的网格坐标数据。将冷季定义为11月至次年2月, 其中前两个月为早期冷季, 后两个月为晚期冷季, 极端低温定义为冷季温度范围中的P10。利用时间分层的病例交叉设计结合分布滞后非线性模型, 分析冷季的温度与死亡的关联以及不同滞后时间下极端低温与死亡的关联, 并比较冷季早期(11—12月)与晚期(1月至次年2月)的季节内差异。结果 2013—2018年山东省冷季四个月温度变化范围为(-17.3~18.6)℃, P10(即极端低温)为-13.7 ℃。冷季早期日均温度为(3.63±4.66)℃, 晚期日均温度为(-0.09±3.70)℃;冷季早期日均相对湿度为(63.89±14.75)%, 晚期日均相对湿度为(62.27±14.19)%。山东省2013—2018年冷季死亡1 473 300例, 其中男性824 601例(55.97%);年龄<65岁者349 824例(23.75%);死于循环系统疾病803 691例(54.55%), 死于呼吸系统疾病140 415例(9.53%)。分布滞后非线性模型模型分析结果显示, 以冷季最适温度18.6 ℃为参考, 冷季4个月极端低温的累积OR为1.74(95%CI:1.63, 1.86);冷季早期和晚期累积OR分别为1.50(95%CI:1.32, 1.71)、2.56(95%CI:2.12, 3.09)(P<0.001);滞后效应持续12 d。结论山东省冷季的低温暴露所致死亡风险存在季节内差异, 冷季晚期高于早期。

Study on the Heat Conduction of Phase-Change Material Microcapsules

The 3ω approach was used to measure the effective thermal conductivity of phase-change material microcapsules (PCMMs) based on urea formaldehyde and sliced paraffin. The effective thermal conductivities of PCMMs with different densities were measured within the phase-change temperature range. The relationships between effective thermal conductivity, density and temperature were analysed. The effective thermal conductivity reached peak values within the phase-change temperature range and the temperature peak value was consistent with the peak value of the phase-change temperature. The effective thermal conductivity increased with increasing density due to the decreased porosity of samples and their increased solid-phase conduction.

Effect of Mn^(2+)on the phosphorus removal and bioflocculation under anoxic condition

Manganese ion(Mn^(2+))generated from metallurgical,steel making and chemical industries enters sewage treatment plants and affects the sludge activity and flocculation.The effect of Mn^(2+)on the removal of chemical oxygen demand(COD)and total phosphorus(TP)and sludge activity were investigated in anoxic zone of an anaerobic/anoxic/oxic(A2O)process.The compositions and structures of extracellular polymeric substances(EPS)were charac-terized using three-dimensional excitation emission matrix fluorescence spectroscopy(3D-EEM),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)to reveal the relationship among Mn^(2+),EPS and sludge flocculation.The results showed thatlow concentration of Mn^(2+)(<5 mg/L)improved removal efficiencies of COD and TP and increased the activity of alkaline phosphatase,acid phosphatase and dehydrogenase.Meanwhile,the addition of Mn^(2+)increased total EPS,sludge contact angle,Zeta potential and sludge particle size,and thus enhanced sludge flocculation.However,high concentration of Mn^(2+)(>10 mg/L)hindered microbial flocculation and reduced removal efficiencies of the pollutants.When Mn^(2+)was 5 mg/L,removal efficiencies of COD and TP reached 65%and 90%,respectively.Sludge flocculation was the best and SVI was 70.56 mL//g.The changes of Mn^(2+)concentration caused deviation of groups'compositions in LB-EPS and TB-EPS,where the main components were always protein(PN)and polysaccharide(PS).The addition of Mn^(2+)resulted in the degradation of humic acids.However,it did not give rise to significant morphology changes of EPS.

Synthesis and properties of polybenzazoles containing flexible methylene in backbone

A novel series of polybenzazoles with rigid-rod benzoxazole cycle and soft methylene segment was designed and synthesized via solution condensation poly-merizations from 4,6-diamino-l,3-benzenediol dipho-sphate,terephthalic acid and aliphatic dicarboxylic acid.The structures of polybenzazoles were characterized by means of FT-IR,1H NMR and Wide-angle X-ray diffrac-tion(WAXRD).All the polymers show excellent thermal stability and the TdS was above 471℃,The intrinsic vis-cosities[η]of the polymers ranged from 0.8 to 0.9.The UV-Vis absorption peaks of the polymers in MSA were blue-shifted from 429 nm for PBO to 291 nm for PBOC7,and the Stokes shifts in PL spectra enlarged.

Modulation and Voltage Balancing Control of Dual Five-level ANPC Inverter for Ship Electric Propulsion Systems

Open-end winding motors are used extensively in ship electric propulsion systems,in which medium-voltage high-power inverters are a critical component.To increase the system voltage and power density,a dual five-level active neutral-point clamped(ANPC)inverter is proposed herein to drive medium-voltage open-end winding motors for ship electric propulsion.Each phase of this inverter comprises two five-level ANPC bridges and all the phases are powered by a common direct-current link.A hybrid modulation method is proposed to control this inverter.The series-connected switches in all the five-level ANPC bridges are operated at the fundamental frequency,and the other switches are controlled with a phase-shifted pulse-width modulation(PWM),which can achieve a natural balance between the neutral-point voltage and flying capacitor voltages in a carrier period.A closed-loop capacitor voltage balancing method based on adjusting the duty ratios of the PWM signals is proposed.The neutral-point voltage and flying capacitor voltages can be controlled independently and balanced without affecting the output phase voltage.Simulation and experimental results are presented to demonstrate the validity of this method.