PdNi/Ni Nanotubes Assembled by Mesoporous Nanoparticles for Efficient Alkaline Ethanol Oxidation Reaction

The optimization of structure and composition is essential to improve the performance of catalysts. Herein, mesoporous nanoparticles assembled PdNi/Ni nanotubes (mPdNi/Ni NTs) are successfully fabricated using nickel nanowires as sacrificial template. The combination of nanotubular structure with mesoporous nanoparticle morphology can provide facilitated transfer channels and sufficient active sites, allowing the full contact and reaction between catalysts and reactants. Therefore, the synthesized mPdNi/Ni NTs exhibite superior ethanol oxidation performance to mesoporous Pd nanotubes and commercial Pd black. This study proposes a rational strategy for the development of nanoparticle assembled nanotubes with surface mesoporous morphology, which can greatly improve catalytic performance in various electrocatalytic fields.     

非晶塑性变形机理研究新进展

非晶合金的塑性变形机理一直是材料科学和凝聚态物理研究的热点问题之一.文章简单介绍了近来中国科学院物理研究所在非晶合金塑性机理研究方面的最新进展,介绍了玻璃转变和塑性变形机制之间的关联性及最新的实验证据,以及从非平衡态统计力学角度对非晶塑性变形机制的理解,指出非晶合金的塑性和剪切带的动力学状态密切相关,发现韧性非晶合金在变形过程中可以演化到自组织临界状态.这对认识非晶合金的形成本质,探索具有实际应用价值的非晶合金具有重要意义.     

Milk-Derived Carbon Quantum Dots: Study of Biological and Chemical Properties Provides Evidence of Toxicity

Carbon dots (CDs) are carbon-based zero-dimensional nanomaterials that can be prepared from a number of organic precursors. In this research, they are prepared using fat-free UHT cow milk through the hydrothermal method. FTIR analysis shows C=O and C-H bond presence, as well as nitrogen-based bond like C-N, C=N and –NH₂ presence in CDs, while the absorption spectra show the absorption band at 280 ± 3 nm. Next, the Biuret test was performed, with the results showing no presence of unreacted proteins in CDs. It can be said that all proteins are converted in CDs. Photo luminance spectra shows the emission of CDs is 420 nm and a toxicity study of CDs was performed. The Presto Blue method was used to test the toxicity of CDs for murine hippocampal cells. CDs at a concentration of 4 mg/mL were hazardous independent of synthesis time, while the toxicity was higher for lower synthesis times of 1 and 2 h. When the concentration is reduced in 1 and 2 h synthesized CDs, the cytotoxic effect also decreases significantly, ensuring a survival rate of 60–80%. However, when the synthesis time of CDs is increased, the cytotoxic effect decreases to a lesser extent. The CDs with the highest synthesis time of 8 h do not show a cytotoxic effect above 60%. The cytotoxicity study shows that CDs may have a concentration and time–dependent cytotoxic effect, reducing the number of viable cells by 40%.     

原位电子显微学探索固体中的离子迁移行为

离子在固体材料中的迁移是很多应用的基础,包括锂离子电池、存取器件及催化剂等。研究固体材料中的离子迁移行为是固态离子学的核心内容。微观上,固体中离子迁移的行为取决于材料微观结构所确定的局域势垒特征。因此,研究离子迁移行为与微观结构的关联至为重要。文章讲述了具有高空间分辨率的原位透射电子显微镜技术用于锂离子电池材料、阻变存储材料等体系中离子迁移行为的研究现状与发展趋势。     

用镀有钛过渡层的钼衬底制备无裂纹自支撑金刚石膜

为了解决金刚石膜脱膜开裂的问题,尝试了一种复合衬底,即镀有钛过渡层的钼衬底.利用直流等离子体喷射法在复合衬底上制备了不同厚度无裂纹的自支撑金刚石膜.用扫描电镜(SEM)、拉曼谱和X射线衍射表征金刚石膜的特征,并检测了其断裂强度.结果表明,用复合衬底制备的金刚石膜在950℃具有最小半高宽,在实验温度下所获得的金刚石自支撑膜的断裂强度均超过了500MPa.     

硅烷浓度对微晶硅太阳电池的影响

采用甚高频等离子化学气相沉积技术(VHF-PECVD)制备了系列p-i-n型微晶硅太阳电池,研究了电池有源层硅烷浓度的变化对电池性能的影响.结果发现:随着硅烷浓度的提高电池的短路电流密度先提高然后降低,转换效率与之有相同的变化趋势,而开路电压随硅烷浓度的提高而增加,这些变化来源于有源层材料结构的改变.电池的填充因子几乎不受硅烷浓度的影响,但受前电极的影响很大.不同系列电池转化效率的最高点虽然处于非晶到微晶的过渡区,但对应电池的晶化率不同.另外,研究结果也给出非晶/微晶过渡区随着辉光功率的提高和沉积气压的降低向高硅烷浓度方向转移.     

脉冲Nd:YAG激光熔覆修复塑料模具工艺参数的优化

激光器的电压、电流、脉冲宽度、脉冲频率与激光的扫描速度、光斑直径等工艺参数直接影响着脉冲Nd:YAG激光熔覆质量。为了简化工艺调整过程,提出了重叠率的概念,并进行了理论推导,建立了重叠率与脉冲频率、激光扫描速度、激光光斑直径相互关系的方程式。利用预置法在低碳钢基体上熔覆Ni基合金粉末,获得了2组最佳工艺参数,即单脉冲能量、重叠率分别为6.7 J,97.4%和21 J,69.4%。研究表明：在单脉冲能量和重叠率一定的条件下,改变电流、脉宽、脉冲频率及熔覆速度不会影响熔覆质量。     

强脉冲软X光辐照薄塑料闪烁体发光特性研究

介绍了Z-pinch实验用软X光功率仪的测量原理,利用“强光一号”产生的强脉冲软X光对薄塑料闪烁体(40 mm×0.1 mm)进行了辐照。实验中,采用两套软X光功率仪并安装在同一个大法兰面上,其中一套作为标准系统,参数保持不变,另一套系统的狭缝宽度逐渐增加,以改变软X光辐照到闪烁体上的能量通量密度。测量了软X光的辐射功率,由此计算得到在强脉冲软X光辐照下发光线性输出时能量通量密度下限,为1.47×105 W/cm2,为以后在Z-pinch物理诊断中合理安排探测系统提供了实验依据,使诊断结果更加合理和准确。     

Development of Optogenetic Dual-Switch System for Rewiring Metabolic Flux for Polyhydroxybutyrate Production

Several strategies, including inducer addition and biosensor use, have been developed for dynamical regulation. However, the toxicity, cost, and inflexibility of existing strategies have created a demand for superior technology. In this study, we designed an optogenetic dual-switch system and applied it to increase polyhydroxybutyrate (PHB) production. First, an optimized chromatic acclimation sensor/regulator (RBS10–CcaS#10–CcaR) system (comprising an optimized ribosomal binding site (RBS), light sensory protein CcaS, and response regulator CcaR) was selected for a wide sensing range of approximately 10-fold between green-light activation and red-light repression. The RBS10–CcaS#10–CcaR system was combined with a blue light-activated YF1–FixJ–PhlF system (containing histidine kinase YF1, response regulator FixJ, and repressor PhlF) engineered with reduced crosstalk. Finally, the optogenetic dual-switch system was used to rewire the metabolic flux for PHB production by regulating the sequences and intervals of the citrate synthase gene (gltA) and PHB synthesis gene (phbCAB) expression. Consequently, the strain RBS34, which has high gltA expression and a time lag of 3 h, achieved the highest PHB content of 16.6 wt%, which was approximately 3-fold that of F34 (expressed at 0 h). The results indicate that the optogenetic dual-switch system was verified as a practical and convenient tool for increasing PHB production.     

Alkaloids and Colon Cancer: Molecular Mechanisms and Therapeutic Implications for Cell Cycle Arrest

Cancer is the second most fatal disease worldwide, with colon cancer being the third most prevalent and fatal form of cancer in several Western countries. The risk of acquisition of resistance to chemotherapy remains a significant hurdle in the management of various types of cancer, especially colon cancer. Therefore, it is essential to develop alternative treatment modalities. Naturally occurring alkaloids have been shown to regulate various mechanistic pathways linked to cell proliferation, cell cycle, and metastasis. This review aims to shed light on the potential of alkaloids as anti-colon-cancer chemotherapy agents that can modulate or arrest the cell cycle. Preclinical investigated alkaloids have shown anti-colon cancer activities and inhibition of cancer cell proliferation via cell cycle arrest at different stages, suggesting that alkaloids may have the potential to act as anticancer molecules.