高教评估主体中政府行为之探讨

高教评估主体中,具有直接性、强制性、复杂性的政府评估行为是有法律依据的,也具有很大的积极作用;但由于"立法懈怠、政出多门、权责不清、政府角色错位"等因素的制约,导致政府行为具有相当大的局限性,存在诸多弊端.为此政府应加强立法,健全制度,对评估主体进行结构性调整,建立评估委托制度、评估机构的认证制度、行业准入制度,组织开展元评估,促进高教评估的深入开展.     

DOP计数扫描法在高效过滤器安装泄漏检测中的应用

高效过滤器安装泄漏检测是空气净化技术检测的关键项目之一,结合实际工程论述了采用DOP计数扫描法检测高效过滤器安装泄漏的应用,对采用气溶胶和粒子计数器的采样要求作了规定。为了提高检漏的工作效率和保证采样结果的有效性,提出增加正压检漏的方法。     

Bifunctional photocatalyst with tailored interface scale for cooperative glycerol selective oxidation and H2 evolution

We propose to fabricate a bifunctional photocatalyst for cooperative glycerol selective oxidation and H₂ evolution. The key role of interface scale (nanometer, subnanometer, or atomic level) on tuning catalysis performance was revealed. Specifically, series Pt/defective TiO₂ with tailored interface scale were constructed by loading Pt nanoparticle, cluster, and single atom on V_Ti-enriched TiO₂. It was uncovered that reducing interface scale could largely improve the visible-light utilization efficiency, the photoexcited electron–hole separation, and well tuned the band structure. It could also enhance the metal–support interaction and thus adjust the chemical behavior toward reactant molecules. The optimized isolated Pt/defective TiO₂ with atomic-level interface achieved 90.6% glycerol conversion and 87.2% C₃ products selectivity, accompanied by 7250.4 μmol g⁻¹ H₂ accumulative yield. It also exhibited long-term stability of 36 h without performance loss. Besides, the dominate active site was identified and the possible reaction mechanism was illustrated combined with Density Functional Theory (DFT) calculation and quasi in situ experiments.     

Mass Transfer Model of Oriented Silicon Steel Coil during the First Soaking in Annular Furnace

Silicon - Surface oxidation of the oriented silicon steel usually occurs during the first soaking in annular furnace. It negatively influences the magnetic performance and the MgSO4 coating of the...     

表面活性剂增敏差分脉冲阳极溶出伏安法测定食品中痕量铅

在0.1mol/L NaNO_3和适量十六烷基三甲基溴化铵(CTAB)介质中,采用玻碳汞膜电极作为工作电极,差分脉冲阳极溶出伏安法测定金属Pb的增敏效果可达10倍左右,其溶出峰为-0.47V(V.S.Ag/AgCl 1mol/L KCl),线性范围为0～100ppb,其准确度和回收率分别在4.6%～9.9%和92%～114%之间。     

苯磺酸甜菜碱表面改性阳离子交换膜

采用等离子体辉光放电技术,在以聚苯乙烯为基膜的阳离子交换膜表面接枝苯磺酸甜菜碱(SBMA)单体,制备出具有高选择透过性的阳离子交换膜。对改性前后的膜进行扫描电镜(SEM)、傅里叶红外光谱分析(FTIR)及氯离子泄漏率测试,表征膜的改性效果。结果表明:在SBMA浓度为60g/L,等离子照射强度为0.7 W/cm2,照射时间为7min,照射气体氛围为氩气的条件下,改性效果最佳。改性膜含有的活性基团明显增多,表面致密均匀,氯离子泄漏率由原膜的14%降低至2%以下。     

Superelastic Carbon Aerogels: An Emerging Material for Advanced Thermal Protection in Extreme Environments

Carbon aerogels (CAs) are desirable for thermal protection in aerospace because of their lightweight and high-temperature insulation characteristic; however, their intrinsic brittleness and flaw sensitivity easily trigger catastrophic failure when resisting high-frequency thermal shocks or complex mechanical stresses. Compression is the predominant load applied on aerogels by aerodynamic pressure and pre-tightening force; therefore, the structural elasticity and exceptional capability to keep thermal performance under impact stress are crucial in deciding the actual availability of aerogels. This review presents the recent progress in newly resilient CAs for thermal protection, focusing on reliable structural stability, thermal stability, and thermal superinsulation property. The influence law of microstructures on heat transfer behaviors is first investigated, followed by construction strategies for adiabatic CAs, emphasizing the recoverable deformability resulting from increased continuity of building blocks from 0D nanoparticles to 1D nanofibers/nanotubes and then to 2D nanosheets. Moreover, the optimization of thermal stability in high-temperature aerobic environments and thermal insulation performance are discussed. Finally, it raises current challenges and further opportunities for CAs toward better properties and brighter prospects.     

采后茶青叶对振动力胁迫的生理响应

摇青是乌龙茶品质形成的关键工序之一,其通过机械胁迫引起各种生物学效应,影响植物体内一系列生理生化变化,被广泛应用于花香红茶、花香白茶、花香绿茶等茶类的加工中以改善品质。为探明青叶响应机械力胁迫的生理变化,以采摘的‘铁观音’品种中开面三、四叶嫩梢为材料,经适度萎凋后进行自然摊放和振动力胁迫处理,研究青叶水分含量、光系统Ⅱ(photosystem Ⅱ,PS Ⅱ)参数、抗氧化酶活力及亚细胞结构的变化规律。结果表明：振动力胁迫30 min内青叶水分含量与自然摊放叶、萎凋叶间无显著差异（P>0.05）,60 min时显著低于自然摊放叶和萎凋叶（P<0.05）。随着振动力胁迫时间延长,青叶青臭气增强,清香减弱;叶绿体和类囊体紧密而清晰的片层结构逐渐松散、变形、收缩、紊乱、瓦解,振动力胁迫处理5 min时淀粉粒数量明显增加,15 min时嗜锇颗粒数量明显增多,出现聚集。振动力胁迫青叶的PS Ⅱ实际光合效率Y(Ⅱ)和光化学猝灭系数qP随处理时间延长总体呈下降趋势,电子传递速率（electron transfer rate,ETR）随处理时间延长呈先降低后升高趋势,5 min和10 min时...     

Understanding the Visible Absorption of Electron Accepting and Donating CNDs

Carbon nanodots (CNDs) synthesized from citric acid and formyl derivatives, that is, formamide, urea, or N-methylformamide, stand out through their broad-range visible-light absorbance and extraordinary photostability. Despite their potential, their use has thus far been limited to imaging research. This work has now investigated the link between CNDs’ photochemical properties and their chemical structure. Electron-rich, yellow carbon nanodots (yCNDs) are obtained with in situ addition of NaOH during the synthesis, whereas otherwise electron-poor, red carbon nanodots (rCNDs) are obtained. These properties originate from the reduced and oxidized dimer of citrazinic acid within the matrix of yCNDs and rCNDs, respectively. Remarkably, yCNDs deposited on TiO₂ give a 30% higher photocurrent density of 0.7 mA cm⁻² at +0.3 V versus Ag/AgCl under Xe-lamp irradiation (450 nm long-pass filter, 100 mW cm⁻²) than rCNDs. The difference in overall photoelectric performance is due to fundamentally different charge-transfer mechanisms. These depend on either the electron-accepting or the electron-donating nature of the CNDs, as is evident from photoelectrochemical tests with TiO₂ and NiO and time-resolved spectroscopic measurements.     

Ultra-Stretchable Spiral Hybrid Conductive Fiber with 500%-Strain Electric Stability and Deformation-Independent Linear Temperature Response

Stretchable configuration occupies priority in devising flexible conductors used in intelligent electronics and implantable sensors. While most conductive configurations cannot suppress electrical variations against extreme deformation and ignore inherent material characteristics. Herein, a spiral hybrid conductive fiber (SHCF) composed of aramid polymeric matrix and silver nanowires (AgNWs) coating is fabricated through shaping and dipping processes. The homochiral coiled configuration mimicked by plant tendrils not only enables its high elongation (958%), but also generates a superior deformation-insensitive effect to existing stretchable conductors. The resistance of SHCF maintains remarkable stability against extreme strain (500%), impact damage, air exposure (90 days), and cyclic bending (150 000 times). Moreover, the thermal-induced densification of AgNWs on SHCF achieves precise and linear temperature response toward a broad range (−20 to 100 °C). Its sensitivity further manifests high independence to tensile strain (0%–500%), allowing for flexible temperature monitoring of curved objects. Such unique strain-tolerant electrical stability and thermosensation hold broad prospects for SHCF in lossless power transferring and expeditious thermal analysis.