Synthesis of the 3D porous carbon-manganese oxide (3D-C@MnO) nanocomposite and its supercapacitor behavior study

A 3D porous carbon-manganese oxide ([email protected]) nanocomposite is successfully synthesized via a thermal plasma deposition method. The chemical bonds and compositions, phase structures, surface morphologies, etc. of as-obtained [email protected] nanocomposite were characterized by the various equipment, such as X-ray diffractometer, X-ray photoelectron spectroscopy, and electron microscopes. The electrochemical performances of the [email protected] nanocomposite electrode showed a specific capacitance of 780 F g^?1 at a current density of 2 A g^?1 and a capacitance retention rate of 99% after 5000 charge-discharge cycles at a high current density of 10 A g^?1. These excellent capacitive performances may be attributed to the encapsulation of MnO nanoparticles by porous carbon sheets in the [email protected] MnO nanocomposite structure. It is believed that the carbon-encapsulated MnO nanoparticles can be protected from a volume deformation during the charge adsorption/desorption cycle and can be electrically improved by the encapsulated carbon sheets, resulting in better overall capacitive performance. In addition, this study also demonstrates the practical applicability by assembling a supercapacitor using the as-obtained [email protected] nanocomposite to glow a light emitting diode.     

An ultra-sensitive non-enzymatic hydrogen peroxide sensor based on SiO2-APTES supported Au nanoparticles modified glassy carbon electrode

A novel electrochemical sensor based on (3-aminopropyl)triethoxysilane (APTES) functionalized SiO₂ supported Au nanoparticles and Nafion (Nf) as the protective membrane was fabricated for the electrochemical determination of H₂O₂ in contact lens-cleaning solution. The modification steps of glassy carbon working electrode (GCE) were evaluated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The amperometric results showed that Nf/[email protected]₂-APTES/GCE sensor can be used to determine H₂O₂ in contact lens solutions with the linear ranges of 14–180 μM and 0.18–7.15 mM, excellent sensitivities of 2514.6 and 894.2 μA mM cm^?2, and a low limit of detection (LOD) of 4.25 μM depending upon signal-to-noise ratio of 3. Nf/[email protected]₂-APTES/GCE exhibited excellent repeatability with relative standard deviation (RDS) of 2.66% and acceptable reproducibility with RSD of 3.35%. The sensor displayed reasonable selectivity in the presence of uric acid, dopamine, ascorbic acid, glucose, mannose, glycine, fructose, histidine, and arginine with RSD less than 2.5%. The fabricated Nf/[email protected]₂-APTES/GCE sensor has been successfully applied to detect H₂O₂ in contact lens cleaning solutions.     

Fabrication and electrochemical properties of 3D nano-network LiFePO_4@multiwalled carbon nanotube composite using risedronic acid as the phosphorus source

LiFePO_4@multiwalled carbon nanotubes(LFP@MWCNTs) nanocomposite has been fabricated using risedronic acid(RDA) as a new eco-friendly phosphorus source. Microscopic, spectroscopic, and electrochemical characterization demonstrate that the MWCNTs are in the form of coiled and cross-linking nanoribbon, which wrapped and encrusted around LiFePO_4 particles to form a three-dimensional(3D) nano-network composite.This microstructure of 3D nano-network is obtained due to the reactions between RDA's special functional groups with Fe~(2+) and C-OH,-C=O or-COOH on the surface of the functionalized MWCNTs. The results also show that the particle size of the fabricated LiFePO_4@MWCNTs composite is below 300 nm with the pure crystal of olivine. This nanocomposite indicates an enhanced reversible capacity of 162.2 mAh g~(-1) at 0.2C, and high capacity retention of 76.5% even at 10C after the 800 th cycles. The electric conductivity and Li~+ diffusion coefficient(D_(Li)~+) of the LiFePO_4@MWCNTs are 3.79 × 10~(-2)S cm~(-1) and 4.46 × 10~(-11) cm~2s~(-1), respectively.These improved electrochemical parameters can be attributed to the nano-sized effect of particles, MWCNTs' wrapping effect and 3D nano-network microstructure of the LFP@MWCNTs resulted from using RDA as a new phosphorus source.     

Hydroxyapatite/alumina nanocrystalline composite powders synthesized by sol-gel process for biomedical applications

Hydroxyapatite/alumina nanocrystalline composite powders needed for various biomedical applications were successfully synthesized by sol-gel process. Structural and morphological investigations of the prepared composite powders were performed using X-ray diffractometer (XRD), scanning electron microscopy (SEM), X’Pert HighScore software, and Clemex Vision image analysis software. The results show that the crystallite size of the obtained composite powders is in the range of 25 to 90 nm. SEM evaluation shows that the obtained composite powders have a porous structure, which is very useful for biomedical applications. The spherical nanoparticles in the range of 60 to 800 nm are embedded in the agglomerated clusters of the prepared composite powders.     

CoPt-Co hybrid supported on amino modified SiO_2 nanospheres as a high performance catalyst for hydrogen generation from ammonia borane

CoPt-Co hybrids were successfully supported on amino modified SiO_2 nanospheres by a chemical reduction method at a temperature of 278 K.The solid carrier i.e.amino modified SiO_2,provides numerous anchoring sites for the metal nanoparticles(NPs)to improve the dispersion while reducing the size of metal NPs.The supported NPs displayed a narrow particle size distribution on the SiO_2 surface with an average diameter of 12 nm.The XRD results alongside with the binary alloy phase diagram suggest that the resulted NPs are bimetallic,composed of CoPt and amorphous Co.Among the prepared materials,the solid with the specific composition of SiO_2@Pt_(0.1)Co_(0.9)was proved to be effective catalyst for ammonia borane(AB)hydrolysis in aqueous solution.The turnover frequency(TOF)value of the supported nanocatalyst was 25.59mol_(H_2)min~(-1)·mol_M~(-1),almost twice as that of unsupported Pt_(0.1)Co_(0.9)NPs while the activation energy was 37.05 kJ mol~(-1).Furthermore,the SiO_2@Pt_(0.1)Co_(0.9)composite manifested high catalytic activity even after five cycles of reuse.     

Microstructure/texture evolution maps to optimize hot deformation process of near-α titanium alloy

The microstructure/texture evolution(MTE,for short) map and processing map of a new near a titanium alloy Ti65 were constructed in order to investigate the workability and microstructure evolution of hot deformation.The processing map illustrated four domains,two summit domains and two instability domains.The morphologies of the a phase changed from the spheroidization(α+β region) to the deformed and elongated β grains(near the βtransus temperature T_β),and then to the obvious dynamic recrystallization(DRX)(β region) with the temperature rising from 930 ℃ to 1140℃.Deformation in the α+β field mainly generated the texture component with [0001]or [0223] parallel to radial directions(RDs).While deformation in the β phase field formed two types of texture component with [0001] parallel to RDs and [2110] parallel to compression direction.An optimized processing map was summarized by overlaying the macro-instability map on the original processing map,and the instability domain of Ti65 alloy was confirmed in the area with the strain rate higher than 0.01 s~(-1).     

单分散Au/ZnO纳米球的可控制备及气敏性能研究

以二水合醋酸锌和二甘醇为原料,采用微波法制备ZnO单分散纳米球;采用柠檬酸还原法制备Au纳米颗粒,并通过静电作用将金纳米颗粒修饰在ZnO纳米球上制备Au/ZnO气敏材料.XRD结果证明了多晶ZnO的形成以及金属Au的成功修饰;FESEM和TEM观察到ZnO单分散纳米球由纳米颗粒组装而成,粒径约280nm;PL光谱对合成材料的晶体缺陷进行了提取,在此基础上深入讨论了Au/ZnO的增敏机理.气敏测试结果显示,Au/ZnO纳米球比未修饰的ZnO纳米球对丙酮具有更好的选择性与更低的检测温度,在体积分数为1×10-6下仍具有较强的气敏响应.     

广西北海市的鸟类资源

【目的】对北海市鸟类资源进行全面调查分析。【方法】于2005—2016年对广西壮族自治区北海地区的鸟类进行调查,结合查阅历史资料文件记载,归纳总结全市的鸟类资源。【结果】在北海地区共记录鸟类455种,留鸟种类均较少,多数鸟类在北海为候鸟,其中国家一级重点保护鸟类3种,数量均极为稀少,国家重点保护动物69种,包括数量众多的隼形目猛禽。【结论】北海是西伯利亚、东亚、东北亚候鸟迁往西太平洋群岛、东南亚、南亚以及非洲大陆的重要通道和停歇地。北海地区候鸟数量众多,但由于内陆和滨海湿地退化,以及盗猎野生鸟类行为导致大型水鸟在该地区缺失。因此需在春秋两季迁徙季节加强候鸟保护工作。     

Dissolution characteristics of sericite in chalcopyrite bioleaching and its effect on copper extraction

The effects of sericite particle size, rotation speed, and leaching temperature on sericite dissolution and copper extraction in a chalcopyrite bioleaching system were examined. Finer particles, appropriate temperature and rotation speed for Acidithiobacillus ferrooxidans resulted in a higher Al3+ dissolution concentration. The Al3+ dissolution concentration reached its highest concentration of 38.66 mg/L after 48-d leaching when the sericite particle size, temperature, and rotation speed were -43 μm, 30℃, and 160 r/min, respectively. Meanwhile, the sericite particle size, rotation speed, and temperature can affect copper extraction. The copper extraction rate is higher when the sericite particle size is finer. An appropriately high temperature is favorable for copper leaching. The dissolution of sericite fitted the shrinking core model, 1-(2/3)α-(1-α)2/3=k₁t, which indicates that internal diffusion is the decision step controlling the overall reaction rate in the leaching process. Scanning electron microscopy analysis showed small precipitates covered on the surface of sericite after leaching, which increased the diffusion resistance of the leaching solution and dissolved ions.     

CdS光化学修饰介孔TiO2及其增强的可见光催化活性

[目的]提高介孔TiO₂材料的光催化活性。[方法]采用蒸发诱导自组装法(EISA),以四氯化钛和钛酸丁酯为钛源,嵌段共聚物P123(EO₂₀PO₇₀EO₂₀)为模板剂,制备介孔TiO₂。用光化学修饰法将CdS掺进介孔TiO₂中,合成对可见光有较好响应的复合材料,并利用X射线衍射(XRD)、透射电镜(TEM)、原子吸收分光光度法(AAS)和光催化等手段对样品进行表征。[结果]XRD和TEM结果表明成功合成有序的六方介孔材料;AAS确定复合材料中Cd的含量为0.96mg/g;光催化于500 W氙灯下以2×10^-5mol/L次甲基蓝(MB)为模型污染物,结果显示CdS/TiO₂复合材料的可见光催化活性明显提高。[结论]光化学修饰法制备的介孔CdS/TiO₂复合材料可增强其可见光催化活性。     

Rapid point-of-use water purification using nanoscale zero valent iron (nZVI) particles

Nanoscale zero-valent iron (nZVI) particles are increasingly being investigated in removing aqueous contaminants. Here, we have demonstrated its inactivation and magnetic removal of bacteria and endotoxins from environmental wastewater samples. Varying dosages (10–1,000 μL) of 0–6 days aged nZVI with a concentration of 5 mg/mL for 2 mL wastewater samples were tested, and relevant removal efficiencies were determined using culturing method for bacteria and limulus amebocyte lysate (LAL) for endotoxins. The supernatants of wastewater samples after reacting with nZVI and subsequent magnetic separations were subjected to spectroscopic, qPCR and DGGE analysis. Overall, high magnetic bacterial removal efficiencies were observed up to 3–4 logs for 1 mL nZVI, while the removal efficiencies decreased sharply down to 0.5 log for 10 μL nZVI. qPCR and DGGE results revealed that higher dosages of nZVI caused severe bacterial cell membrane ruptures, releasing significant amounts of DNA up to 10⁷–10⁸ gene copies/mL when 1 mL nZVI was used. Richer DGGE patterns were observed for higher nZVI dosages. In addition, regardless of the dosages (10–1,000 μL) we have observed more than 90 % removal of endotoxins from the wastewater samples. The described technology has great promise to be used as a point-of-use water purification solution for various purposes.     

微波消解-ICP-OES法测定小叶榕药材中微量元素

【目的】建立一种小叶榕（Ficus microcarpa）药材中微量元素的测定方法。【方法】采用微波消解样品,电感耦合等离子体质谱法（ICP-OES）测定小叶榕药材中12种微量元素的含量。【结果】电感耦合等离子体质谱法测定药材中微量元素的含量线性好、操作简便、快速准确、灵敏度高。小叶榕药材中含量丰富的微量元素,从高到低依次为Mg、Fe、A1、Mn、Zn等。【结论】建立了微波消解-ICP-OES测定小叶榕药材中多种微量元素的分析方法。     

机械合金化-热处理制备V5Si3材料

[目的]为了获得V/Si类化合物基本结构和性能,拟合成V/Si系金属间化合物V_5Si_3。[方法]采用V粉和Si粉作原料,按照原子比V∶Si=5∶3进行称量,通过机械合金化与热处理制备V_5Si_3,再利用XRD,SEM/EDS等方法对球磨粉体试样和热处理试样的物相组成、微观形貌和微区成分进行分析与表征,并测量其抗压性能和硬度。[结果]V/Si粉体经过球磨后颗粒度减小,逐渐非晶化,最终得到以原子比V∶Si=5∶3结合的非晶态物质;经过热处理,非晶态结构转变为V_5Si_3晶体。[结论]随着热处理温度的升高,晶体结晶度提高,材料的抗压强度和显微硬度增加,抗压强度达到640 MPa,显微硬度最高为656 MPa。     

Cu-FeOx@AC活化PMS体系除藻效能与机制

为探究富营养化水体中藻类的新型治理技术，通过水热法和高温煅烧法，使颗粒活性炭（AC）表层上负载铜铁双金属氧化物Cu-FeO_x，制得可回收的Cu-FeO_x@AC复合催化剂。以XRD、SEM、FTIR和XPS对Cu-FeO_x@AC的表征为基础，研究Cu-FeO_x占AC的负载比、过一硫酸盐（PMS）使用量、初始pH及不同反应体系对除藻的影响，探究Cu-FeO_x@AC活化过一硫酸盐体系的除藻效能。Cu-FeO_x@AC活化过一硫酸盐体系反应机理，通过自由基淬灭实验、XPS表征进行探究。结果可知，初始pH为6，初始藻细胞密度为1.4×10⁹个/L，使用催化剂0.5 g/L，PMS 0.2 g/L时，反应90 min，该体系对藻的降解率有97.25%。在该体系中，藻细胞能被吸附在Cu-FeO_x@AC复合催化剂表面，在铜、铁不同价态离子的转换及AC的协同作用下，产生空穴、·O2-、·OH、SO4-·，单线态氧等多种氧化基团而被去除。     

高腐蚀条件下用铝合金材料腐蚀机理

铝合金具有低密度、低熔点、高比强度及优良的耐腐蚀性能等特点，被广泛用于航空航天、建筑、船舶等领域。在服役过程中，铝合金的表层氧化膜易受到环境中活性阴离子的破坏而发生腐蚀，对其性能造成严重的损害，故研究铝合金在高腐蚀性环境的腐蚀行为对工程选材具有非常重要的指导意义。选择6061铝合金、2195铝锂合金和7075铝合金为研究对象，对其在特定腐蚀介质中的腐蚀过程和力学性能进行分析，研究了铝合金在特定腐蚀介质中腐蚀形貌与力学性能的变化规律。结果表明：腐蚀初期，在高Cl^-、NO₂^3-、SO₂^4-离子浓度的腐蚀环境中，3种铝合金的氧化膜受到阴离子破坏后发生点腐蚀，使基体暴露在腐蚀环境中，进而发生电化学腐蚀，6061铝合金和2195铝锂合金腐蚀方式是由点腐蚀向面腐蚀转变，7075铝合金腐蚀方式为晶间腐蚀；经过腐蚀后6061铝合金能保持稳定的强度和塑性，7075铝合金和2195铝锂合金的强度和塑性都明显降低。     

丙烯酰胺/氧化-还原引发体系的反相乳液聚合

采用煤油为油相,Span80和Op10为复配乳化剂,以K2S2O8-Na2SO3氧化-还原体系为引发剂,研究了丙烯酰胺的反相乳液聚合.通过考察引发剂浓度、单体浓度、乳化剂用量、反应温度对反应速率及分子量的影响,确定了动力学表达式: Rmax∝[I]0.68 [M]1.290[E]0.71,Mη∝[I]-3.66[M]0.640[E]-0.77;聚合表观活化能Ea=41.11 kJ/mol.反应速率-时间曲线上未出现恒速平台,聚合过程不存在恒速期;扫描电镜未观察到反应后乳胶粒径比反应前乳胶粒径有数量级的下降;搅拌速率较低时,聚合反应的转化率-时间曲线常呈不规则形状,结果不易重复且乳胶粒径较大,这些都证实该聚合反应的成核机理为单体液滴成核.     

厄尔尼诺-南方涛动影响下月尺度水文模型参数可移植性

以浙江省3个流域作为研究对象，采用两参数月水量平衡模型（XM模型）和四参数月水量平衡模型（ABCD模型），结合极大似然不确定性估计方法（GLUE）对水文模拟的不确定性区间进行估计，在此基础上，研究不同模型在ENSO（厄尔尼诺-南方涛动）和不同流域地理情况下的参数移植能力。结果表明，厄尔尼诺时期的参数移植至拉尼娜时期，模型模拟效果要略好于拉尼娜时期的参数移植至厄尔尼诺时期；参数少的模型（XM模型）参数移植合格率要优于参数多的模型（ABCD模型）；相邻流域间的参数移植效果要明显优于距离较远的流域；ABCD模型具有更好的空间可参数移植能力。     

Peptide segment ligation: A new method for synthesis of peptide and protein

The protein structure-function relationships are al-ways highlighted in the field of life science. Protein syn-thesis from genomic sequence data is gaining significance in the post-genomic era of biomedical research by pro-viding direct access to functional proteins. The manually or automatically stepwise solid phase peptide synthesis (SPPS) allows peptide of up to 60 residues to be routinely constructed in good yield and high purity[1,2]. The assem-bly of longer proteins via the gene engine…