Synthesis,sinterability and ionic conductivity of nanocrystalline Pr-doped La2Mo2O9 fast oxide-ion conductors

A new series of nanocrystalline La_2−xPr_xMo₂O₉ (0.2 ≤ x ≤ 0.8) powders are synthesized through the pyrolysis of polyacrylate salt precursors prepared via in situ polymerization of the metal salts and acrylic acid. The polymeric precursors are characterized by thermogravimetric and differential thermal analysis (TG/DTA) to determine the thermal decomposition and crystallization temperature, which is found to be at 510 °C. X-ray diffraction analysis indicates that the substitution of La by Pr preserves the single-phase La₂Mo₂O₉ structure up to a Pr dopant concentration of x ≤ 0.7. The particle size and the α → β phase transition of the Pr-doped La₂Mo₂O₉ samples are studied by using a transmission electron microscope (TEM) and differential scanning calorimetry (DSC), respectively. The sintering behaviour of the Pr-doped samples are examined via isothermal and non-isothermal experiments. It demonstrates that the synthesized nanocrystalline powders have good sinterabilty and a relatively low sintering temperature of 800 °C for 4 h is sufficient to reach ∼99% of the theoretical density with good microstructures. Furthermore, the oxide-ion conductivity increases with increasing Pr content and the maximum conductivity is attained at x = 0.5 in La_2−xPr_xMo₂O_9.     

溅射功率对CIGS吸收层前驱膜成分和结构的影响

采用中频交流磁控溅射方法制备了CuIn、CuGa和CIG合金膜。采用SEM和XRD观察和分析了各种薄膜的表面形貌、成分和组织结构。着重分析了靶功率密度对薄膜成分、晶体结构的影响。结果表明,通过调节靶功率密度,能精确控制薄膜中CuI、n、Ga比例。制备得到了Cu/(In Ga)原子比接近1,且Ga/(In Ga)比例可调的成分分布均匀的CIG薄膜。CIG前驱膜是以Cu11In9为基础相,Ga原子主要是以替代In原子的固溶体形式存在。当溅射CuIn和CuGa合金靶的功率密度分别为0.26和0.10 W/cm2时,可制备得到由Cu11In9和CuIn两相组成的理想的CIG前驱膜。     

Synthesis and characterization of precursor derived TiN@Si–Al–C–N ceramic nanocomposites for oxygen reduction reaction

The development of efficient and durable catalysts is critical for the commercialization of fuel cells, as the catalysts’ durability and reactivity dictate their ultimate lifetime and activity. In this work, amorphous silicon-based ceramics (Si–C–N and Si–Al–C–N) and TiN@Si–Al–C–N nanocomposites were developed using a precursor derived ceramics approach. In TiN@Si–Al–C–N nanocomposites, TiN nanocrystals (with sizes in the range of 5–12 nm) were effectively anchored on an amorphous Si–Al–C–N support. The nanocomposites were found to be mesoporous in nature and exhibited a surface area as high as 132 m²/g. The average pore size of the nanocomposites was found to increase with an increase in the pyrolysis temperature, and a subsequent graphitization of free carbon was observed as revealed from the Raman spectra. The ceramics were investigated for electrocatalytic activity toward the oxygen reduction reaction using the rotating disk electrode method. The TiN@Si–Al–C–N nanocomposites showed an onset potential of 0.7 V versus reversible hydrogen electrode for oxygen reduction, which seems to indicate a 4-electron pathway at the pyrolysis temperature of 1000°C in contrast to a 2-electron pathway exhibited by the nanocomposites pyrolyzed at 750°C via the Koutecky–Levich plot.     

Polymer-derived β-SiAlON:Eu2+ phosphors

A series of β-SiAlON:Eu²⁺ phosphors were synthesized from single-source precursors, perhydropolysilazane chemically modified with Al(OCH(CH₃)₂)₃, AlCl₃, and EuCl₂. The single-source precursors were converted to β-SiAlON:Eu²⁺ phosphors by pyrolysis under flowing N₂ or NH₃ at 1000°C, followed by heat treatment at 1800°C under an N₂ gas pressure at 980 kPa. By varying the molar ratio of the chemical modifiers, β-SiAlON:Eu²⁺ with the compositions close to the theoretical ones expressed as Si_6−zAl_zO_z−2yN_8−z+2y:yEu²⁺ were synthesized, where the z values and Eu²⁺ contents were controlled in the ranges of .44–.78 and .35–1.48 mol%, respectively. The polymer-derived β-SiAlON:Eu²⁺ phosphors exhibited green emission under excitation at 460 nm attributed to the 4f⁷–4f⁶(7f³)5d¹ transition of dopant Eu²⁺. High-angle annular dark-field-scanning transmission microscopy analysis confirmed that the doped-Eu²⁺ existed interstitially within the channels along the c axis of host β-SiAlON. Compared with the conventional powder metallurgy route, the polymer-derived ceramic route in this study offers some advantages in the grain growth of host β-SiAlON and photoluminescence properties in terms of green emission intensity under excitation at 460 nm, and the highest intensity was achieved for the polymer-derived β-SiAlON:Eu²⁺ with z = .64 and .37 mol% Eu²⁺.     

氢氧化物前驱体制备LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2的机理

用共沉淀法制备前驱体Ni0.5Co0.2Mn0.3(OH)2,焙烧前驱体与Li2CO3制备Li Ni0.5Co0.2Mn0.3O2。用XRD、SEM和DSCTGA分析焙烧中间产物的结构、形貌及变化,探索制备Li Ni0.5Co0.2Mn0.3O2的机理。随着焙烧温度的升高,前驱体分解成(Ni0.5Co0.2Mn0.3)3O4,随后Li2CO3参与反应,形成Li Ni0.5Co0.2Mn0.3O2。Li Ni0.5Co0.2Mn0.3O2的生成在650℃时结束,但层状结构在900℃时才趋于完美。     

米酒生香酵母的分离筛选鉴定及其性能研究

为获得米酒酿造中优良的生香酵母,通过嗅闻法初筛得到6株香气突出的菌株,通过测定菌株发酵米酒过程中乙酸乙酯、β-苯乙醇、乳酸乙酯和乙醇的积累量,复筛获得菌株11Z1,其积累量分别为(2.883±0.260)、(0.301±0.028)、(0.080±0.008)和(37.296±1.036)g/L。经形态学及分子生物学方法鉴定菌株11Z1为Cyberlindnera fabianii;对其发酵液进行风味物质分析,检测出主要风味物质共21种,包括醇类5种、酯类3种、酸类5种、酚类1种、酮类1种、烷烃类2种和其他类4种,这些风味物质对增加酒的香气及形成酒体风格具有积极作用。此外,分别在培养基中添加风味前体物乙酸、L-苯丙氨酸和L-乳酸,进一步探究其对菌株11Z1酿造米酒风味物质形成的影响,结果表明,添加体积分数0.3%乙酸发酵9 d、8 g/L L-苯丙氨酸发酵4 d、体积分数0.4%L-乳酸发酵8 d,乙酸乙酯、β-苯乙醇及乳酸乙酯积累量分别达到最大,与未添加前体物相比分别提高了160.71%、215.48%和144.04%。综上,菌株11Z1具有突出的生香能力,展现出在米酒酿造中巨大的应用潜力。     

尖晶石型锂离子筛吸附剂前驱体的合成研究

利用离子记忆效应机理以Li2CO3和MnCO3为原料,结合TG-DTA、XRD和TEM等分析法,采用高温固相反应法合成了粒度大小为300nm～500nm、近乎纯相的尖晶石型锂吸附剂前驱体(LiMn2O4),该前驱体酸洗后可用于从低含锂溶液提锂。研究了原料配比、焙烧温度和升温速率等因素对产物的影响,确定了合适的合成条件为:Li/Mn摩尔比0.5,升温速率10℃/min,800℃保温5h。     

蛋白质组学揭示滩羊宰后成熟过程中风味前体物质的变化机理

为探讨宰后滩羊肉成熟过程中风味前体物质变化的机理,采用同位素标记相对和绝对定量技术（isobaric tags for relative and absolute quantification,iTRAQ）结合多维液相色谱串联质谱（liquid chromatography-tandem mass spectrometry,LC-MS/MS）技术研究滩羊背最长肌在各成熟时间点（0、4 d和8 d）的蛋白质组学变化情况。结果表明：滩羊肉不同成熟期差异表达蛋白主要包括代谢酶、结构蛋白和应激蛋白。随着宰后成熟的进行,代谢酶中磷酸丙糖异构酶、烯醇酶3、L-乳酸脱氢酶、磷酸葡萄糖变位酶1和丙酮酸激酶（与风味相关的关键代谢物调控酶）在成熟0～4 d时活性上调且变化较明显;而肌钙蛋白C1、肌钙蛋白T3、肌球蛋白轻链2、肌球蛋白轻链1、原肌球蛋白3和热休克蛋白70的表达量在成熟0～4 d时上调,在成熟4～8 d时下调较明显。采用实时荧光定量聚合酶链式反应检测滩羊肉中差异表达蛋白在mRNA转录水平上的基因相对表达量,宰后成熟过程中有4 个差异表达蛋白在0～4 d和4～8 d时蛋白水平和mRNA转录水平的表达模式一致,分别为2 个代谢酶（L-乳酸脱氢酶和磷酸丙糖异构酶）和2 个结构蛋白（肌球蛋白轻链2和肌动蛋白α1）。综上,宰后滩羊肉成熟过程中代谢酶的调控、结构蛋白的降解和应激蛋白的防护共同对风味前体物质的变化起调控作用。     

PAN原丝废丝制备新型季戊四醇酯及其应用

以PAN原丝废丝为原料合成新型季戊四醇酯,并将其运用于聚氯乙烯（PVC）共混助剂中.通过流变仪和热老化试验机测试研究了该季戊四醇酯在PVC共混中的稳定性.结果表明,采用PAN原丝废丝为原料合成的季戊四醇酯的热稳定性能相对较好,可作为PVC的稳定助剂,为PAN原丝废丝赋予了新的可利用性.     

Synthesis and characterization of mesoporous anatase TiO2 nanostructures via organic acid precursor process for dye-sensitized solar cells applications

Titania (TiO₂) nanoparticles have been synthesized using organic precursor technique. The titania nanoparticles were characterized. The results indicated that the prepared titanium oxalate and citrate precursors were transformed to anatase TiO₂ phase at temperature 400 °C for 2 h. Dye-sensitized solar cells were assembled using the prepared nanocrystalline TiO₂ with large surface area. The specific surface area S_BET was 80.9 and 78.6 m²/g using oxalic and citric acids, respectively. The power efficiency was 3.5 and 2.4%. A brief discussion on the possible reasons behind the low power conversion efficiency observed for these type of solar cells was reported.