高效液相色谱法定量尿酸、黄嘌呤和次黄嘌呤在人体血清中的浓度

目的: 建立高效液相色谱法测定尿酸、黄嘌呤和次黄嘌呤在人体血清中的浓度。方法: 用Agilent ZORBAX SB-Aq column色谱柱,ZORBAX-Extend C₁₈预柱,以甲醇和 47 mmol/L KH₂PO₄水溶液作为流动相,流速:1.0 mL/min,检测波长为 260 nm。结果: 血清中尿酸、黄嘌呤和次黄嘌呤的线性范围分别是(1.667~166.667)×10³ ng/mL (r=0.9995)、(0.033~3.338)×10³ ng/mL(r=0.9994)和 (0.033~3.338)×10³ ng/mL (r=0.9996),日间与日内精密度均<15%。结论: 该法灵敏度高,精密度和准确度佳,能满足非布司他体内药效学研究。     

不同工艺下镁合金MAO/GO/SA复合涂层的耐蚀性

为提高AZ91D镁合金基体的耐蚀性，采用微弧氧化、电沉积和自组装工艺在AZ91D镁合金表面制备了微弧氧化/氧化石墨烯/硬脂酸(MAO/GO/SA)复合涂层。通过SEM对复合涂层的微观组织结构进行了分析，利用电化学阻抗谱、极化曲线测试了复合涂层的耐蚀性能。结果表明，最佳电沉积电压为4 V,此时，MAO/GO复合涂层的电荷转移电阻(R_ct)为4.41×10⁵Ω·cm²,腐蚀电流密度(J_corr)为3.88×10^-7 A/cm²。醇水比为7∶3时，MAO/GO/SA复合涂层的R_ct值为3.07×10⁶Ω·cm²,J_corr为3.02×10^-8 A/cm²,达到超疏水状态，涂层耐蚀性最好。     

Ti-22Al-25Nb合金板材高温拉伸变形行为的本构模型

在1203～1283 K的温度范围内,以20 K的温度间隔对O相Ti-22Al-25Nb合金进行了等温单向拉伸试验,应变速率为2.5×10^-4、5.0×10^-4、1×10^-3、2×10^-3、4×10^-3、1×10^-2和5×10^-2 s^-1,并对不同变形温度下的试样组织进行了表征。通过实验结果,确定了本构模型的材料常数;α₂+B2/β+O三相区(1203～1243 K)和α₂+B2两相区(1243～1283 K)的拉伸变形激活能分别为845 165和412 779 J/mol。构建了Arrhenius本构模型来描述Ti-22Al-25Nb合金在不同温度下的拉伸变形行为。     

杂质镓对纯铝表面锆钛转化膜的组织及耐腐蚀性能的影响

目的 探究杂质镓对纯铝锆钛转化膜的生长规律和防护性能的影响。方法 采用扫描电化学显微镜(SECM)技术表征了含镓纯铝表面锆钛转化膜在3.5%(质量分数)NaCl溶液中局部腐蚀的演变过程,结合X射线衍射仪(XRD)、X射线光电子能谱(XPS)、扫描电镜(SEM)等技术分析了镓对纯铝锆钛转化膜的组织及成分的影响规律,采用开路电位法(OCP)、电化学阻抗技术(EIS)以及极化曲线(Tafel)等探究了杂质镓对纯铝表面转化膜的生长和耐腐蚀性能的影响规律。结果 锆钛转化膜主要由冰晶石Na₃AlF₆、氧化物(如TiO₂、ZrO₂、Al₂O₃)和有机金属络合物组成;杂质镓的添加会抑制铝表面转化膜的生长,破坏膜层的完整性。随镓含量(质量分数)从0%增大到0.5%,锆钛转化膜阻抗值从4.75×10⁴?·cm²不断减小到2.49×10³?·cm²,自腐蚀电流密度由0.45μA增加到13.4...     

高铁酸盐(Ⅵ)与毒砂表面的作用机理及其对黄铜矿与毒砂浮选分离的影响（英文）

通过浮选试验、接触角测量、吸附量测试、交流阻抗测试和XPS分析研究一种新型环保抑制剂高铁酸钾(K₂FeO₄)在乙基黄药捕收剂体系下对毒砂和黄铜矿的抑制作用。结果表明,在pH值为4～11的范围内,高铁酸钾强烈抑制毒砂,在pH 8或10时,采用5×10^-4 mol/L K₂FeO₄和5×10⁵ mol/L PEX可以实现黄铜矿与毒砂的浮选分离。在K₂FeO₄和PEX存在时,毒砂的接触角和黄药吸附量显著降低。LEIS测量表明,高铁酸盐的加入可以显著增加毒砂表面的阻抗。XPS分析进一步证实,高铁酸盐加速毒砂表面的氧化。     

MgAl2O4:Eu3+荧光粉的制备及其光谱特性

采用水热辅助固相法合成一系列Eu³⁺掺杂MgAl₂O₄:Eu³⁺荧光粉。主要考察粉体的物相结构、形貌、颗粒尺寸及电/磁偶极跃迁强度随Eu³⁺摩尔分数的变化规律。结果表明:当Eu³⁺不等价取代Mg²⁺后并未影响基质材料的晶体结构,产物全部为立方相MgAl₂O₄,但间隙O^2?的存在会影响被取代离子Mg²⁺的配位关。当Eu³⁺掺入时,其会与溶液中的NH₄⁺共同参与调控样品的形貌和尺寸,以致片状颗粒的厚度减小、不规则程度加剧。基于J-O理论认为,在248 nm紫外和395 nm近紫外光激发下,Eu³⁺在MgAl₂O₄中所处格位的对称性差异是引起电偶极(⁵D₀→⁷F₂)和磁偶极(⁵D₀→⁷F₁)跃迁相对强度不同的主要原因。     

N-乙酰胆碱受体动力学研究

目的 开展N-乙酰胆碱受体(N-AChR)的动力学研究。方法 (1)选择a-BuTX作为主要工具药,进行¹²⁵I-a-BuTX与电鳐电器官的N-AChR饱和结合实验,用Seatfit程序拟合。¹²⁵I-a-BuTX与电鳐电器官的N-AChR结合的解离动力学实验,当结合达到饱合后,向两个反应体系分别加入1000 倍以上的a-BuTX或烟碱。不同时间取样、分离后, γ-计数仪计数。(2)13日龄的鸡胚骨骼肌N-AChR及20日龄的鸡视叶的N-AChR与¹²⁵I-a-BuTX饱和结合实验,用Scatfit程序拟合。另外以烟碱对¹²⁵I-a-BuTX与电鳐电器官、鸡视叶、鸡胚骨骼肌N-AChR结合的竞争实验,用Logit程序计算ICso值。结果 (1) ¹²⁵I-a-BuTX 与电鳐电器官的N-AChR饱和结合实验得到一条双曲线的Scatchard图,符合一配基两受体结合模型,求得高、低两个结合位点和两个B_max(最大结合值)。两个体系的解离动力学均为二次解离曲线,分别求得两个解离常数和两个半衰期。(2)两种实验结果,均符合一配基一受体结合模型,分别求得一个结合位点和一个B_max。烟碱对¹²⁵I-a-BuTX电鳐电器官的N-AChR结合的竞争作用IC₅₀ 值分别为3.86X 10^-5和1.65x10^-1 mol。对鸡视叶的N-AChR竞争作用IC30值为6.02x107 mol,对骨骼肌竞争作用ICxo 值为4.60x 10^-1。结论 (1)电鳐电器官中 存在¹²⁵I-a-BuTX的高亲和力位点和低亲和力位点。(2) ¹²⁵I-a-BuTX 对鸡视叶和鸡胚骨骼肌N-AChR亲和力差异显著,烟碱对a-BuTX分别与鸡视叶和鸡胚骨骼肌N-AChR竟争作用的ICo值相差7.7倍,表明鸡视叶和骨骼肌存在着两种不同的N-AChR亚型。     

废旧磷酸铁锂电池高值回收制备磷酸铁锂材料

针对传统湿法冶金回收废旧磷酸铁锂电池存在含磷废水排放量大、产品附加值低等问题，提出一种还原酸浸-沉淀-固相再生回收废旧磷酸铁锂正极材料的新方法。区别于传统氧化酸浸，本研究在浸出过程中加入有机还原剂，将铁元素以Fe²⁺的形式浸出到溶液中；然后，通过控制pH值制备Fe₃(PO₄)₂·8H₂O，以此作为再生LiFePO₄正极材料的前驱体，避免了后续混锂烧结过程中Fe³⁺还原不彻底、再生磷酸铁锂纯度低等问题。结果表明：通过控制浸出条件，Li⁺和Fe²⁺的浸出率分别达到98.15%和98.10%。利用氨水调控浸出液pH值，沉淀出形貌为一次片状簇拥成团状结构的Fe₃(PO₄)₂·8H₂O前驱体；最后，将Fe₃(PO₄)₂·8H₂O...     

装载缓蚀剂的蒙脱土对环氧涂层耐蚀性能的研究

将不同比例的装载缓蚀剂蒙脱土和环氧树脂混合制备出纳米复合环氧涂层。根据电化学阻抗谱 (EIS) 和盐雾实验对涂层的耐蚀性进行表征。结果表明,3%装载蒙脱土环氧涂层的水扩散系数为9.89×10^-11 cm²/s,孔隙率为2.22×10^-8,整个浸泡过程中阻抗值在10⁹ Ωcm²以上,表现出最佳的耐蚀性。     

维生素K3 在MTT 比色法检测真菌数量中的剂量关系探讨

目的: 确定维生素K₃ (VK₃) 在MTT 比色法检测活菌数量时的实验用量。方法: 微孔板和MTT 比色法检测不同VK₃ 含量在测量活菌数量中的作用。结果: OD 值随着菌浓度、VK₃ 含量的升高而增大。溶解剂作用时间对实验组影响不大。菌浓度高时测定波长对OD 值有显著影响,反之则影响不显著。结论: 菌浓度在10⁶ 数量级,VK₃ 含量为0.1mmol·L^-1,测定波长为570 nm 时所得OD 值结果较为可靠、稳定。     

Precursor solution prepared by evaporation deamination complex method for solvent separation of Mo and W by H2O2-complexation

An novel method on preparation of precursor solution for solvent separation of molybdenum (Mo) and tungsten (W) by hydrogen peroxide (H₂O₂)-complexation from the ammonium tungstate solution containing high Mo was studied. The precursor solution was obtained via evaporation deamination and H₂O₂-complex transformation processes. Then it was extracted with a mixture extractant of tri-alkyl phosphine oxide (TRPO) and tributyl phosphate (TBP) to separate Mo and W. The results indicated that the evaporation deamination complex method reduced the acid consumption by more than 90% in comparison with the traditional directly acid regulation complex method. The transformation rates of W and Mo were higher than 95% and the decomposition rate of H₂O₂ was less than 15% at a 1.8-1.9 times H₂O₂ dosage, 45-50 °C, initial pH of 1.80-1.90, and transformation volume ratio of 100% for 60 min in the H₂O₂-complexation transformation process. The minimum extraction rate of W was 2%, the maximum extraction rate of Mo was 82.6% and the highest separation coefficient was 76.7 in a single-stage extraction.     

Crystal structure and negative thermal expansion properties of solid solution Er2W3-xMoxO12

A series of solid solutions Er₂W_3?xMo_xO₁₂ (0.5≤x≤2.5) were successfully synthesized by the solid state method. Their crystal structures and negative thermal expansion properties were studied by high temperature X-ray powder diffraction and the Rietveld method. All samples with rare earth tungstates and molybdates crystallize in the same orthorhombic structure with space group Pnca, and show the negative thermal expansion phenomena related to transverse vibration of bridging oxygen atoms in the structure. Thermal expansion coefficients (TECs) of Er₂W_3?xMo_xO₁₂ were determined as ?16.2×10^?6 K^?1 for x=0.5 and ?16.5×10^?6 K^?1 for x=2.5 while ?20.2×10^?6 K^?1 and ?18.4×10^?6 K^?1 for unsubstituted Er₂W₃O₁₂ and Er₂Mo₃O₁₂ in the identical temperature range of 200?800 °C. High temperature XRD data and bond length analysis suggest that the difference between W—O and Mo—O is responsible for the change of TECs after the element substitution in the series of solid solutions.     

Color-conversion and photoluminescence properties of Ba2MgW(Mo)O6:Eu phosphor

Compounds B₂AXO₆:Eu (B = Ba, Sr; A = Ca; and X = W, Mo) have recently been investigated and suggested to be color-conversion phosphor for WLED devices. In this work, we investigated the photoluminescence properties of the analogues Ba₂MgXO₆:Eu (X = W and Mo) and the energy transfer from W(Mo)O₆ groups to Eu³⁺ ions within the phosphors. The phase structure, UV-vis diffuse reflectance spectrum, photoluminescence properties and decay of Ba₂MgW_(1−x)Mo_xO₆:Eu were studied as a function of the W/Mo ratio. It was found that these phosphors showed excellent color-conversion capability from near-UV to orange-red light. The color-conversion process was considered to be performed by energy transferring from MoO₆ groups to doped Eu³⁺ ions. The MoO₆ → Eu³⁺ energy transfer efficiency could be greatly enhanced by partial substitution of Mo by W. The structure and photoluminescence properties of Ba₂AW_0.5Mo_0.5O₆:Eu (A = Ca and Mg, respectively) compounds were also investigated to reveal the effect of the Eu³⁺ ion coordination environment on its photoluminescence properties.     

Effect of secondary carbides addition on the microstructure and mechanical properties of (Ti, W, Mo, V)(C, N)-based cermets

(Ti, W, Mo, V)(C, N)-based cermets were prepared by mixing Mo₂C, WC and TaC with ultrafine (Ti, W, Mo, V)(C, N) powders, and then processed via a conventional P/M technique. The effect of Mo₂C, WC and TaC on the microstructure and mechanical properties of (Ti, W, Mo, V)(C, N)-8 wt.% Ni-7 wt.% Co systems was investigated. The Mo₂C content was varied from 0 to 10 wt.% and additive WC or TaC was added at a level of 5 wt.% with Mo₂C addition. The results show that the densification of (Ti, W, Mo, V)(C, N)-8 wt.% Ni-7 wt.% Co cermets was improved significantly by the addition of Mo₂C. With the increase of Mo₂C content, there is a coarsening tendency in the microstructure of (Ti, 20W, 15Mo, 0.2V)(C, N)-8Ni-7Co system, but the refinement for (Ti, 15W, 5Mo, 0.2V)(C, N)-8Ni-7Co. TaC addition decreases the density of (Ti, 15W, 5Mo, 0.2V)(C, N)-10Mo₂C-8Ni-7Co cermet and thus weakens its bending strength. (Ti, 15W, 5Mo, 0.2V)(C, N)-10Mo₂C-5WC-8Ni-7Co cermet has optimal mechanical properties: bending strength of 1999 MPa, hardness (H_v) of 1677 MPa and toughness of 9.95 MPa m^1/2 respectively by adding WC, which is due to its ultrafine and weak core/rim structure.     

Effect of carbon on formation of mixed solid solutions during mechanochemical synthesis of Ni-Al-Mo-C mixtures and ordering of solutions during heating

Solid solutions Ni(Al, Mo, C) are formed via milling the Ni_2.8Al₁Mo_0.2 and Ni₃Al_0.8Mo_0.2 and graphite-containing Ni_2.8Al₁Mo_0.2C_{(0.25, 0.5)} and Ni₃Al_0.8Mo_0.2C_{(0.25, 0.5)} mixtures. In this case, some amount of Mo remains beyond the solid solution. Graphite added to a starting mixture decreases the Mo solubility and favors the amorphization of solid solutions. The complete amorphization was found for the mixture with the 5 at % C and 5 at % Mo, which was added instead of Ni. The heating of mechanically synthesized (MS) powder alloys leads to the ordering of carbon-free and carbon-containing solid solutions with the formation of the L1₂ and E2₁ structure, respectively. In the course of the ordering of the Ni(Al, Mo, C) solid solutions, Mo and carbon precipitate in the form of the molybdenum carbide (Mo₂C) second phase. The hardness of the MS three-phase Ni-Al-Mo-C solid solutions subjected to hot isostatic pressing is determined by the mass fraction of the formed Mo₂C carbide. It is shown that the carbon content in the multicomponent antiperovskite can be estimated by analyzing the ratio of integral intensities of superlattice reflections I ₍₁₀₀₎/I ₍₁₁₀₎.     

Phase evolution of hydrothermal synthesis oxide-doped molybdenum powders

MoO₃ and oxide-doped molybdenum powders have been recently attracted considerable attention due to their superior sensing and photocatalysis properties and great lubricity. In the present study, we report synthesis powders of Mo doped with Al₂O₃, ZrO₂ or La₂O₃ oxides, respectively, via calcination and hydrogen reduction of uniform and well-crystallized MoO₃·(H₂O)_0.333 nanosheets synthesized by a facile hydrothermal synthesis method. Results show the MoO₃·(H₂O)_0.333 was transformed to h-MoO₃, β-MoO₃, α-MoO₃, MoO₂ and Mo in sequence in calcining and reduction process. The three kinds of oxides have a similar effect on the powders in inhibiting grain growth to promote grain refinement at each stage, but they have different effect on growth morphology of Mo particles. The metal oxides (Al₂O₃, ZrO₂) do not affect the morphology of Mo particles, and Mo particles grow into microsphere spontaneously. Nevertheless, the rare earth oxide La₂O₃ with higher surface activity changes the coordination environment of MoO bonds and growth process of Mo particle, resulting in a polygonal shape of Mo particles. The Mo powders doped with 1.2 vol%Al₂O₃ have a fine size of 2 μm, regular morphology and good distribution.     

Removal of tungsten and vanadium from molybdate solutions using ion exchange resin

The removal of tungsten (W) and vanadium (V) from molybdate solutions was studied using the poly hydroxyl chelating resin D403 in batch and column experiments. The batch experiments indicated that tungsten and vanadium could be preferentially adsorbed by the D403 resin for 4 h in molybdate solution at a pH of approximately 9.25. Separation factors, α_Mo^V and α_Mo^W, were above 45 and 18, respectively, when the molar ratios of Mo/V and Mo/W in the solution exceeded 40. Elution tests illustrated that vanadium and tungsten could be easily eluted from the resin with 1 mol/L sodium hydroxide solution in only 1 h. To further explore the sorption mechanism of the resin, the experimental equilibrium isotherm data of the three metals fitted well with the Freundlich model. The column experiments confirmed the adaptability of the D403 resin in the production of sodium molybdate with a removal rate of tungsten surpassing 90% and that of vanadium of 99.4%.     

The borocarbides Mo2−xWxBC (0⩽×⩽1.1), a new family of refractory superconducting materials

Large single crystals of Mo₂BC have been obtained by a Czochralski procedure above 2500 °C. The crystals are characterized by X-ray diffraction, optical metallography, and microprobe analysis. Tungsten substitution in Mo₂BC has been investigated. Resistance to oxidation and microhardness increase with increasing tungsten content in the borocarbides series Mo_2?xW_xBC (0?×?1.1) has been shown. A study of magnetization as a function of the field at different temperatures has been carried out. All borocarbides are type-II superconductors. Both the critical superconductivity temperature T_cr, and critical field,H_c2, decrease with x.     

Complexation extraction of scheelite and transformation behaviour of tungsten-containing phase using H2SO4 solution with H2C2O4 as complexing agent

The extraction of tungsten from scheelite was carried out using a sulfuric acid solution with oxalic acid as the chelating agent. Tungsten was obtained in the form of highly soluble hydrogen aqua oxalato tungstate (H₂[WO₃(C₂O₄)·H₂O]) during the leaching process, while calcium remained in the residue as calcium sulfate dihydrate (CaSO₄·2H₂O). About 99.2% of the tungsten was leached at 70 °C, 1.5 mol/L sulfuric acid, 1 mol/L oxalic acid, a liquid/solid ratio of 25:1 (mL/g), an oxalic acid to sulfuric acid molar ratio of 1:1, a stirring speed of 300 r/min and a leaching time of 2 h. H₂[WO₃(C₂O₄)·H₂O] was thermally decomposed into tungstic acid (H₂WO₄), and tungsten trioxide (WO₃) was directly produced by calcining H₂WO₄ at 700 °C for 2 h. The surface chemical reaction was determined to be the controlling step during tungsten leaching, and the apparent activation energy was calculated to be 51.43 kJ/mol.     

Structure analysis of the constitutional phases in liquid phase sintered W–Mo–Ni–Fe heavy alloys

The crystal structures of constitutional phases in two different tungsten heavy alloys processed via different conditions were examined. The compositions of these two alloys were W–11.9Mo–17.0Ni–7.7Fe and W–29.6Mo–17.0Ni–7.7Fe (at.%), which were liquid phase sintered at 1500 °C for 5 or 240 min, and followed by either furnace-cooling or water-quenching. Increase in isothermal hold caused increased concentration of Mo but decreased concentration of W in the matrix phase, which did not affect the lattice parameter of the matrix phase to a significant extent. Quenching the specimen in water caused increase in the concentrations of both W and Mo in the matrix phase, and, consequently, increases in the lattice parameter of the matrix phase. A tungsten heavy alloy with a high alloying concentration of Mo was prone to induce the precipitation of an intermetallic phase during cooling, which was enhanced by increasing the isothermal hold at the liquid phase sintering temperature and decreasing the cooling rate. The structure of this intermetallic phase is analogous to that of MoNi, and can be designated as (W_xMo_1−x)(Fe_yNi_1−y). The composition of this intermetallic phase varied with the composition of the alloy and its cooling rate subsequent to sintering. For a furnace-cooling condition, the atomic ratio of W to Mo (x/1−x) in this intermetallic phase was about 0.47 times the atomic ratio of W to Mo of the original alloy composition. Such a proportional constant decreased to about 0.30 when the specimen was water-quenched.