乳液模板法制备聚酰亚胺中空微球及其形貌调控

以聚酰胺酸(PAA)为前驱体、甲基硅油(SO)为油相、乙醇和水作为沉淀剂,采用乳液模板法制备了聚酰亚胺(PI)中空微球。重点研究了沉淀剂中乙醇的比例、PAA溶液的固含量及PAA溶液/SO体积比对微球粒径和形貌的影响;采用光学显微镜、扫描电镜、红外光谱和热重分析仪对微球的形成过程、粒径和形貌、化学结构和热稳定性进行了表征。当沉淀剂中乙醇/水体积比为1:1、PAA溶液固含量为6%、PAA溶液/SO体积比为1:1时,PI微球的粒径为4.75μm。制备出的PI中空微球均具有较好的热稳定性,其起始热分解温度为442℃。

Ultralow Interfacial Thermal Resistance of Graphene Thermal Interface Materials with Surface Metal Liquefaction

Developing advanced thermal interface materials(TIMs)to bridge heat-generating chip and heat sink for constructing an efficient heat transfer interface is the key technology to solve the thermal management issue of high-power semiconductor devices.Based on the ultra-high basal-plane thermal conductivity,graphene is an ideal candidate for preparing high-performance TIMs,preferably to form a vertically aligned structure so that the basal-plane of graphene is consistent with the heat transfer direction of TIM.However,the actual interfacial heat transfer efficiency of currently reported vertically aligned graphene TIMs is far from satisfactory.In addition to the fact that the thermal conductivity of the vertically aligned TIMs can be further improved,another critical factor is the limited actual contact area leading to relatively high contact thermal resistance(20-30 K mm^(2) W^(−1))of the“solid-solid”mating interface formed by the vertical graphene and the rough chip/heat sink.To solve this common problem faced by vertically aligned graphene,in this work,we combined mechanical orientation and surface modification strategy to construct a three-tiered TIM composed of mainly vertically aligned graphene in the middle and micrometer-thick liquid metal as a cap layer on upper and lower surfaces.Based on rational graphene orientation regulation in the middle tier,the resultant graphene-based TIM exhibited an ultra-high thermal conductivity of 176 W m^(−1) K^(−1).Additionally,we demonstrated that the liquid metal cap layer in contact with the chip/heat sink forms a“liquid-solid”mating interface,significantly increasing the effective heat transfer area and giving a low contact thermal con-ductivity of 4-6 K mm^(2) W^(−1) under packaging conditions.This finding provides valuable guidance for the design of high-performance TIMs based on two-dimensional materials and improves the possibility of their practical application in electronic thermal management.

从任务驱动到专业驱动——师范生教学实习管理创新路径探析

鉴于师范生在教学实习中一般性能力与专业能力发展方面的差异,探索了在限制条件下教学实习驱动机制的创新路径。在分析当前教学实习中任务驱动的限制后,主张以专业驱动激活师范生对专业本质的认识,提升自主成长的动力。以此为原则,提供了一些实习指导工作建议:用直接行动来拓展实践经验,用专业反思来提升实践品质,用专业共同体来激活理论与实践、规则与经验的联结。最终让教学实习成为师范生获得专业能力、走向教师职业的一个积极起点。

糖尿病合并急性心力衰竭的危险因素研究

目的探究糖尿病(DM)合并急性心力衰竭(AHF)的危险因素。方法收集AHF患者196例,将60例合并2型糖尿病(T2DM)患者作为DM组;136例未合并DM作为NDM组。比较两组心功能、肝功能、肾功能、血脂及红细胞系统指标。结果两组年龄、抽烟≥10年、心功能分级、合并高血压(HBP)、合并高脂血症(HLP)、肌酐(Cr)、总胆固醇(TC)、三酰甘油(TG)、低密度脂蛋白胆固醇(LDL-C及红细胞平均体积(MCV)比较,差异有统计学意义(P<0.05)。多因素Logistics回归分析显示,HLP、TC及LDL-C为AHF合并DM的危险因素(P<0.05)。结论 HLP、TC及LDL-C与AHF合并DM的发生、发展有密切关系,其增加AHF合并DM的风险。

高效固体酸SBA-15-Zr(OTf)_3催化胺或醇开环环氧化合物（英文）

通过简单的一锅两步法制备了三氟金属(铝,钛,锆)接枝介孔SBA-15(AlTf/S,TiTf/S,ZrTf/S)固体酸材料,并通过XRD,N_2吸附,TGA,FTIR,原位吡啶FTIR和元素分析对这些材料进行了详细的表征.其中,ZrTf/S能够高效催化环氧化物温和条件下被胺或醇开环生成对应β-氨基醇或β-烷氧基醇,并且催化剂能循环利用.ZrTf/S相较于AlTf/S和TiTf/S酸性最强,因而催化活性也最高.

父母忽视与青少年短视频过度使用的关系:正念和自我控制的中介机制

为考察父母忽视与青少年短视频过度使用的关系,并探索正念与自我控制的多重中介机制,选取1015名青少年为研究对象,进行父母忽视、自我控制、正念和短视频过度使用的测量。结果表明:(1)父母忽视与短视频过度使用呈显著正相关。(2)自我控制在父母忽视与短视频过度使用间起中介作用,且正念和自我控制还在两者间起链式中介作用。

Construction and Co-expression of Grass Carp Reovirus VP6 Protein and Enhanced Green Fluorescence Protein in the Insect Cells

Grass carp reovirus(GCRV),a disaster agent to aquatic animals,belongs to Genus Aquareovirus of family Reoviridea.Sequence analysis revealed GCRV genome segment 8(s8) was 1 296 bp nucleotides in length encoding an inner capsid protein VP6 of about 43kDa.To obtain in vitro non-fusion expression of a GCRV VP6 protein containing a molecular of fluorescence reporter,the recombinant baculovirus,which contained the GCRVs8 and eGFP(enhanced green fluorescence protein) genes,was constructed by using the Bac-to-Bac insect expression system.In this study,the whole GCRVs8 and eGFP genes,amplified by PCR,were constructed into a pFastBacDual vector under polyhedron(PH) and p10 promoters,respectively.The constructed dual recombinant plasmid(pFbDGCRVs8/eGFP) was transformed into DH10Bac cells to obtain recombinant Bacmid(AcGCRVs8/eGFP) by transposition.Finally,the recombinant bacluovirus(vAcGCRVs8/eGFP) was obtained from transfected Sf9 insect cells.The green fluorescence that was expressed by transfected Sf9 cells was initially observed 3 days post transfection,and gradually enhanced and extended around 5 days culture in P1(Passage1) stock.The stable high level expression of recombinant protein was observed in P2 and subsequent passage budding virus(BV) stock.Additionally,PCR amplification from P1 and amplified P2 BV stock further confirmed the validity of the dual-recombinant baculovirus.Our results provide a foundation for expression and assembly of the GCRV structural protein in vitro.

普通本科高校专业课程学习现状及实践性教学对策——以南宁师范大学为例

普通本科层次的高校是实施专业教育的机构,通过教授专业知识,培养各级各类专业人才。但是,在当前此类高校的专业学习中,专业教育的深度和广度不足,不能满足社会需求,也不能适应大学生的学习需求。以地方省属普通本科院校为例,对学生专业课程学习状态进行调研,并重点探讨各种实践性教学方式在具体实施中的有效性,提出在专业课堂中实施实践性教学的若干建议。

Scoring system for poor limb perfusion after limb fracture in children

BACKGROUND Assessment of the vascular status following limb fracture in children is important to evaluate the risk of compartment syndrome,which is an emergency condition.AIM To establish a simple and efficient grading scale of limb perfusion in children undergoing surgery for limb fracture.METHODS This retrospective study included pediatric patients with a limb fracture and postoperative plaster fixation who were admitted at The Department of Pediatric Orthopedics of Xinhua Hospital between February 2017 and August 2017.The outcome was poor limb perfusion,which is defined as the postoperative use of mannitol.The children were divided into two groups:The normal perfusion group and the poor perfusion group.Key risk factors have been selected by univariable analyses to establish the Grading Scale for Vascular Status.RESULTS A total of 161 patients were included in the study:85 in the normal perfusion group and 76 in the poor perfusion group.There were no significant differences in age,sex,body mass index,ethnicity,cause of fracture,fixation,or site of fracture between the two groups.After surgery,the skin temperature(P=0.048)and skin color(P<0.001)of the affected limb were significantly different between the two groups.The relative risk and 95%confidence interval for skin temperature of the affected limb,skin color,and range of motion of the affected limb are 2.18(1.84-2.59),2.89(2.28-3.66),and 2.16(1.83-2.56),respectively.The grading scale was established based on those three factors(score range:0-3 points).Forty-one patients(32.5%)with score 0 had poor limb perfusion;all patients with scores 1(n=32)and 2(n=3)had poor limb perfusion(both 100%).CONCLUSION In children undergoing surgery for limb fracture,a higher Grading Scale for Vascular Status score is associated with a higher occurrence of poor limb perfusion.A prospective study is required for validation.

Enhancement of in-plane thermal conductivity of flexible boron nitride heat spreaders by micro/nanovoid filling using deformable liquid metal nanoparticles

With the fast development of integrated circuit devices as well as batteries with high energy densities,the thermal management of electronic components is becoming increasingly crucial to maintaining their reliable operations.Boron nitride nanosheets(BNNS),which have superhigh thermal conductivity along the in-plane direction while remaining electrically insulating,were widely regarded as an ideal filler for preparing high-performance polymer composites to address the‘‘thermal failure''issue.However,due to the instinctive rigidity of BNNS,the nanosheets are unable to form a tightly interfacial contact between the adjoining fillers,resulting in some micro-and nanovoids within the heat transfer pathways and severely limiting further thermal conductivity enhancement for BNNS-based composites.Herein,soft and deformable liquid metal(eutectic gallium-indium,EGaIn)nanoparticles were employed to fill the gaps between the adjacent BNNS with a rational design of mass ratios of BNNS and EGaIn,leading to a strongly synergistic effect with BNNS on thermal conductivity improvement.As a result,the composite film(BNNS:63 wt%and EGaIn:7 wt%)employing cellulose nanofibers(CNF:30 wt%)as the polymer matrix achieves superhigh thermal conductivity along the in-plane direction of up to(90.51±6.71)W·m^(-1)·K^(-1),showing the highest value among the BNNSbased composites with a bi-filler system as far as we know.Additionally,the film can work as a heat spreader for the heat dissipation of high-power light emitting diodes,outperforming tin foil in cooling efficiency.

父母性取向支持、归因方式在男同性恋大学生内化同性恋嫌恶与焦虑间的多重中介效应

目的:考察父母性取向支持、归因方式在男同性恋大学生内化同性恋嫌恶与焦虑间的多重中介机制。方法:选取313名男同性恋大学生,使用内化同性恋嫌恶量表、父母性取向支持量表、归因方式量表、焦虑量表进行测量。结果:男同性恋大学生内化同性恋嫌恶与焦虑呈显著正相关。父母性取向支持在内化同性恋嫌恶与焦虑间存在显著的中介效应,且父母性取向支持与归因方式在内化同性恋嫌恶与焦虑间存在显著的链式中介效应。结论:增强父母的性取向支持和改善自身的归因方式,是缓解高内化同性恋嫌恶男同性恋大学生焦虑水平的有效措施。

Serum sex hormone and growth arrest-specific protein 6 levels in male patients with coronary heart disease

Epidemiological studies have shown a high prevalence of low serum testosterone levels in men with cardiovascular disease. Moreover, the tyrosine kinase receptor Axl, the ligand of which is growth arrest-specific protein 6 （GAS6）, is expressed in the vasculature, and serum GAS6 levels are associated with endothelial dysfunction and cardiovascular events. Testosterone regulates GAS6 gene transcription directly, which inhibits calcification of vascular smooth muscle cells and provides a mechanistic insight into the cardioprotective action of androgens. This study was designed to determine the correlation between serum GAS6 and testosterone levels in male patients with coronary heart disease （CHD）. We recruited 225 patients with CHD and 102 apparently healthy controls, Serum concentrations of GAS6 and soluble Axl were quantified by an enzyme-linked immunosorbent assay. Levels of high-sensitivity C-reactive protein, testosterone, estradiol, and other routine biochemical markers were also measured. Testosterone decreased from 432.69 ± 14.40 to 300.76± 6.23 ng d1-1 （P 〈 0.001） and GAS6 decreased from 16.20± 0.31 to 12.51 ± 0.19 ng ml-1 （P 〈 0.001） in patients with CHD, compared with control subjects. Multiple linear regression analysis showed that serum testosterone and GAS6 levels were positively associated in male patients with CHD. Alterations in GAS6 levels may influence the development of CHD. Downregulation of GAS6/Axl signaling in the presence of low sex hormone levels during disease progression is a potential mechanism by which GAS6 affects CHD. This study provides novel results regarding the influence of sex hormones on serum GAS6 levels in patients with CHD.

Rational design of graphene/polymer composites with excellent electromagnetic interference shielding effectiveness and high thermal conductivity: a mini review

The integration and miniaturization of chips lead to inevitable overheating and increasing electromagnetic interference (EMI) problems, which threaten the performance, stability, and lifetime of electroniccomponents. Therefore, it is important to improve the heat dissipation and EMI shielding performancein device packaging for the steady operation of electronic products. In recent years, due to its intrinsic superior thermal conductivity, proper electrical conductivity, light-weight, and structural adjustability,graphene has been widely used as high thermal and conductive fillers incorporated in the polymer matrix to improve the thermal conductivity and electrical conductivity of composites. This review concludesthe recent development of graphene/polymer composites by using graphene as fillers to improve thethermal conductivity and EMI shielding effectiveness (EMI SE). The structure of graphene embedded inthe composites varies from zero-dimension (0D), one-dimension (1D) to two-dimensions (2D). Moreover,highly thermally and electrically conductive fillers with different dimensions were also modified on thegraphene to improve the composite performance. Finally, this review also makes prospects for the development trend of graphene/polymer composites with high thermal conductivity and EMI SE in the future.

Surfactant-assisted fabrication of graphene frameworks endowing epoxy composites with superior thermal conductivity

With the rapid growth in electronic device performance,there has been an increasing demand for thermally conductive polymer composites to handle the thermal management issue,thus contributing to the great importance to develop the graphene framework,which is evaluated as the most promising reinforcements for enhancing the thermal conductivity of polymer.Vacuum filtration is a common method to fabricate graphene framework,whereas,it is available to prepare a framework with centimeter-scale thickness by filtrating the graphene-water dispersion,due to the fact of sample cracking caused by the mismatch of surface tension between graphene and water.In this work,a surfactantassisted strategy was proposed by adjusting the surface tension of the water close to that of graphene first,then performing a conventional filtration process,to fabricate graphene framework.As a result,a thick graphene framework(thickness:3 cm)was successfully prepared,and after embedding into epoxy,the framework endows the composite(13.6 wt%)with a high in-plane thermal conductivities of12.4 W/mK,which is equivalent to≈64 times higher than that of neat epoxy.Our method is simple and compatible with the conventional filtration process,suggesting great potential for the mass-production of graphene framework to meet the practical application requirements.

Enhanced thermal conductivity of epoxy composites with core-shell SiC@SiO_(2) nanowires

Electronic packaging materials and thermal interface materials(TIMs)are widely used in thermal management.In this study,the epoxy composites with core-shell structure SiC@SiO_(2) nanowires(SiC@SiO_(2) NWs)as fillers could effectively enhance the thermal conductivity of epoxy composites.The unique structure of fillers results in a high thermal conductivity of epoxy composites,which is attributed to good interfacial compatibility epoxy matrix and bridging connections of SiC@SiO_(2) NWs.From neat epoxy to 2.5 wt%loading of SiC@SiO_(2) NWs,the thermal conductivity is significantly increased from 0.218 to 0.391 W m^(−1) K^(−1),increased by 79.4%.In addition,the composite with 2.5 wt%filler possess lower coefficient of thermal expansion and better thermal stability than that of neat epoxy.All these outstanding properties imply that epoxy/SiC@SiO_(2) NWs composites could be the ideal candidate for TIM.

A Spiral Graphene Framework Containing Highly Ordered Graphene Microtubes for Polymer Composites with Superior Through-Plane Thermal Conductivity

As the power density of electronic devices increases,there has been an urgent demand to develop highly conductive polymer composites to address the accompanying thermal management issues.Due to the ultra-high intrinsic thermal conductivity,graphene is considered a very promising filler to improve the thermal conductivity of polymers.However,graphene-based polymer composites prepared by the conventional mixing method generally have limited thermal conductivity,even under high graphene loading,due to the failure to construct efficient heat transfer pathways in the polymer matrix.Here,a spiral graphene framework(SGF)containing continuous and highly ordered graphene microtubes was developed based on a modified CVD method.After embedding into the epoxy(EP)matrix,the graphene microtubes can act as efficient heat pathways,endowing the SGF/EP composites with a high through-plane thermal conductivity of 1.35 W·m^(-1)·K^(-1) at an ultralow graphene loading of 0.86 wt%.This result gives a thermal conductivity enhancement per 1 wt%filler loading of 710%,significantly outperforming various graphene structures as fillers.In addition,we demonstrated the practical application of the SGF/EP composite as a thermal interface material for efficient thermal man-agement of the light-emitting diode(LED).

Dual-functional hydrogen-bonded organic frameworks for aniline and ultraviolet sensitive detection

A novel hydrogen-bonded organic frameworks(HOFs)FJU-200 has been constructed from N,N’-bis(5-isophthalic acid)naphthalimide(H_(4)L).FJU-200 has a good dual-function of aniline and ultraviolet detection.FJU-200 is the first case of HOF with dual sensing of visual color changes and photoluminescence quenching for aniline detection,and the detection limit of aniline can reach5.5 x 10^(-4)mol/L.Under ultraviolet FJU-200 will rapidly change from light yellow to rustic brown,which makes it possible to use FJU-200 to achieve minute-level ultraviolet detection.Moreover,for more convenient use,FJU-200 test papers are prepared.Using them,convenient and fast aniline or ultraviolet detection can be realized.The single-crystal X-ray structures show that compared with the original FJU-200,both PhNH_(2)@FJU-200 and UV-FJU-200 have larger pore sizes,and the dihedral angles of the H_(2)L^(2-)in framework has been changed.

Layer-by-layer stacked graphene nanocoatings by Marangoni self-assembly for corrosion protection of stainless steel

Graphene nanosheets are widely used in anti-corrosion polymeric coating as filler,owing to the excellent electrochemical inertness and barrier property.However,as the arrangement of graphene nanosheets is difficult to form a perfect layered structure,polymeric coating with graphene nanosheets usually needs micron-scale thickness to ensure the enhancement of corrosion protection.In this work,layer-by-layer stacked graphene nanocoatings were fabricated on stainless steel by self-assembly based on Marangoni effect.The anti-corrosion property of graphene coatings were studied through Tafel polarization curves,electrochemical impedance spectroscopy and accelerated corrosion test with extra applied voltage.The self corrosion current density of optimized three-layered graphene coated sample was one quarter of that of bare stainless steel.And the self corrosion potential of optimized sample is increased to-0.045 V.According to the results,graphene nanocoatings composed of layered nanosheets exhibits good anticorrosion property.Besides,the self-assembly method provide a promising approach to make layeredstructure coating for other researches about 2 D material nanosheets.

A dense graphene monolith with poloxamer prefunctionalization enabling aqueous redispersion to obtain solubilized graphene sheets

The realization of good aqueous dispersibility of commercial graphene products composed of exfoliated graphene sheets is of significance for downstream applications.However,the tap density of commercial graphene powder is quite low(0.03-0.1 kg/m3),meaning that 1 kg graphene powder occupies about 10-30 m3 in volume during transportation.And,the available content of commercial graphene dispersion/slurry in aqueous medium cannot exceed 5 wt%,although the density is high(≈1050 kg/m3).In this work,a graphene monolith was prepared by oven-drying of graphene sheets prefunctionalized with poloxamer surfactants.Our graphene monoliths not only have a high density(1500 kg/m^3) and high graphene content(≈10 wt%),but also a full capability to be completely redispersed(≈100%) in water by bath sonication to obtain solubilized graphene sheets,whose lateral size and thickness are unchanged compared to as-exfoliated ones.Moreover,a simple empirical method was proposed to predict the redispersion capability of graphene monoliths using different poloxamers by contact angle measurements.Our results provide a universal approach to make exfoliated graphene-based products with better downstream availability and lower transportation cost.

Rational design of graphene structures for preparing high-performance thermal interface materials: A mini review

With the explosive development in integration of electronic components and the increasing complexity of packaging systems,semiconductor chips own extremely high operation temperatures given by the horrible heat accumulation attributed to the drastically increasing power density. Therefore, highly efficient heat dissipation with the help of rationally designed thermal interface materials(TIMs) is the key to maintaining the device performance and lifespan. Graphene exhibits an ultrahigh intrinsic thermal conductivity, which has attracted a large amount of academic interest due to its significant potential for developing high-performance TIMs. In this tutorial review, we summarize the recent advances in graphene-based TIMs, especially emphasizing the determinate effects of graphene structure and alignment in enhancing the heat transfer capacity of corresponding samples,with detailed discussion in the superiorities and limitations of various graphene skeletons. In addition, we also provide prospects for the challenges and opportunities in the future development of graphene-based TIMs.