Experimental and theoretical studies of carbon monoxide oxidation over W/Cu/Ce trimetallic oxides: the effect of W addition

It is a significant method to prepare highly dispersed polymetallic oxides using in-situ doping metal organic frameworks as precursors. Herein, a series of straw-like W/Cu/Ce trimetallic oxides were prepared by using phosphotungstic ionic liquid@Ce-based metal organic framework adsorbing with copper acetylacetonate as precursors. The effect of W content on catalytic activity of W/Cu/Ce trimetallic oxides for carbon monoxide (CO) oxidation was well-investigated. Comprehensive characterization methods and density functional theory calculations were adopted to reveal the property changes of Cu/CeO₂ catalyst by the addition of W. The results demonstrated that W, Cu, and Ce are highly dispersed in the prepared W/Cu/Ce trimetallic oxides, and adding proper amount of W can improve the activity of the catalyst. H₂ temperature-program reduction profiles, X-ray photoelectron spectroscopy, in-situ diffuse reflectance infrared Fourier transform spectroscopy, and density functional theory calculations clearly revealed that after the addition of W, the strength of Ce-O bond is weakened, the oxygen vacancy is increased, and the adsorption of CO is enhanced, respectively, which are vital reasons for its high catalytic activity. In addition, the CO oxidation reaction pathway over prepared W/Cu/Ce trimetallic oxides based on the Mars-van Krevelen mechanism was studied, and the results exhibited that CO can wrest the lattice oxygen of W/Cu/Ce trimetallic oxides to form CO₂, which is also proved to be the rate-determining step in reaction process.     

模拟胃肠道消化液中小球藻类金属硫蛋白对镉离子的结合作用研究

利用锌诱导小球藻,通过提取分离和纯化,获得锌结合类金属硫蛋白(MT-like蛋白)。通过透析过程,研究模拟胃、肠道消化液中MT-like蛋白对Cd²⁺的结合作用。结果表明,在模拟胃液中MT-like蛋白处于脱金属状态,与Cd²⁺的结合能力弱。而在肠消化液中,MT-like蛋白能与Cd²⁺结合,20 mg·L^-1 MT-like蛋白与100μg·L^-1 Cd²⁺的结合率可达46.0%。研究发现,在模拟胃、肠液中胃蛋白酶和胰蛋白酶都会降低MT-like蛋白对Cd^2+的结合能力。研究结果对进一步开发MT-like蛋白作为Cd²⁺的生物解毒剂具有重要意义。     

6种多金属氧酸盐的抑菌作用

合成了5种过渡金属取代的Keggin型多金属氧酸盐(Na_7PMo_(11)M(Ⅱ)O_(40)(M=Mn,Fe,Zn,Co,Ni)(简写为PMo_(11)M(Ⅱ)),并通过紫外可见分光光度计和傅里叶变换红外光谱仪对其结构进行了表征。进而运用牛津杯法研究了这5种过渡金属取代的Keggin型多金属氧酸盐和母体H_3PMo_(12)O_(40)(简写为PMo_(12))对藤黄八叠球菌、金黄色葡萄球菌、枯草芽孢杆菌和大肠杆菌的抑菌活性,并用微量肉汤二倍稀释法测得了这些(共6种)化合物对上述4种菌的最小抑菌浓度(MIC值)和最小杀菌浓度(MBC值)。结果表明,这6种化合物对4种菌均有不同程度的抑制作用,并且对2种球菌的抑制效果优于对2种杆菌的抑制效果。其中(Na_7PMo_(11)M(Ⅱ)O_(40)(M=Ni,Mn,Zn)对4种菌的抑制效果优于其它3种化合物。综合考虑,本研究能够为多金属氧酸盐用于果蔬的防腐保鲜提供更多的理论和实验支持。     

Dawson结构的多金属氧酸盐对酪氨酸酶的抑制作用

按文献方法合成了两种Dawson结构的多金属氧酸盐,并对其结构进行紫外光谱和红外光谱分析。以H_6[P_2Mo_(18)O_(62)]和H_8[P_2Mo_(17)Cr(OH_2)O_(61)](简写为P_2Mo_(18)和P_2Mo_(17)Cr)为效应物,采用紫外分光光度法和酶动力学方法研究两种Dawson结构的多金属氧酸盐效应物对蘑菇酪氨酸酶二酚酶活性的抑制作用。结果表明,P_2Mo_(18)和P_2Mo_(17)Cr对酪氨酸酶二酚酶均具有显著的抑制效果,测定抑制酪氨酸酶活力下降50%的抑制浓度(IC_(50))分别为(0.482±0.009)mmol/L和(0.503±0.011)mmol/L。动力学分析表明,P_2Mo_(18)和P_2Mo_(17)Cr对酪氨酸酶的抑制作用均表现为可逆的竞争型,抑制常数K_I分别为0.212和0.249 mmol/L。其中,综合考虑IC_(50)值和抑制常数,P_2Mo_(18)对酪氨酸酶二酚酶活性的抑制效果略优于P_2Mo_(17)Cr。     

Quasideterminant solutions of the extended noncommutative Kadomtsev–Petviashvili hierarchy

We construct a nonauto Darboux transformation for the extended noncommutative Kadomtsev–Petviashvili (ncKP) hierarchy and consequently derive its quasi-Wronskian solution. We also obtain the quasi-Wronskian solution of the ncKP equation with self-consistent sources (ncKPESCS) as a by-product. Finally, we use the direct verification method to prove the quasi-Wronskian solution of the ncKPESCS.     

层板复合材料的疲劳剩余刚度统计分布模型

在分析现有关于层板复合材料疲劳剩余刚度衰退模型的基础上，根据层板复合材料在疲劳载荷作用下刚度衰退变化的现象，研究了疲劳载荷对层板复合材料刚度衰退的影响，建立了一个新的、更为合理的用于描述层板复合材料在常幅疲劳载荷作用下的刚度衰退模型，导出了剩余刚度统计分布的表达式，给出了确定模型参数的方法。为验证该模型，设计了几组测试实验，并利用试验结果对模型参数进行了估计。利用该统计分布模型，可以预报层板复合材料在给定应力水平的疲劳载荷作用下循环指定周次时剩余刚度的统计分布。实验数据表明，理论预报和实验结果符合得是很好的。     

染发剂中4种p-苯二胺N位取代衍生物的高效液相色谱测定法

建立了高效液相色谱(HPLC)同时测定染发剂中N,N-双(2-羟乙基)-p-苯二胺硫酸盐(DHPD)、N,N-二甲基-p-苯二胺硫酸盐(DMPD)、N,N-二乙基-p-苯二胺硫酸盐(DEPD)、N-苯基-p-苯二胺盐酸盐(PPD)4种p-苯二胺N位衍生物的方法。采用Agilent Eclipse XDB-C18柱(150 mm×4.6 mm,5μm)为固定相,25 mmol/L磷酸缓冲液(pH 6.0,含0.1%的辛烷磺酸钠)和乙腈为流动相,梯度洗脱,流速1.0 mL/min,柱温25℃,进样量20μL,检测波长250 nm和280 nm。各组分的线性范围为0.1～400 mg/L,相关系数r为0.999 2～0.999 9,检出限为18～108 mg.kg-1,定量下限为42～320 mg.kg-1,RSD<10%,加标回收率为83%～115%。该方法具有简便、快速、准确等特点,基本满足实际样品的分析要求。     

Sound absorption properties of polyurethane foams derived from crude glycerol and liquefied coffee grounds polyol

The main objective of this study was to evaluate the sound absorption properties of rigid polyurethane foams (PUFs) produced from crude glycerol (CG) and/or liquefied coffee grounds derived polyol (POL). The lignin content of POL proved to have a major influence on the structure and mechanical properties of the foams. Indeed, the POL content increased the cell size of the foams and their stiffness, which subsequently influenced the sound absorption coefficients. The POL derived foam has slightly higher sound absorption coefficient values at lower frequencies, while the CG foam has higher sound absorption coefficient values at higher frequencies. In turn, the foam prepared using a 50/50 mixture of polyols presents slightly higher sound absorption coefficient values in the medium frequencies range due to a balance between the cell structure and the mechanical properties. The results obtained seem to suggest that the mechanisms involved in sound wave absorption depend on the formulation used to prepare the foams. Additionally higher POL contents improved the thermal stability of PUFs as well as their mechanical properties. From this work the suitability of CG and/or POL derived PUFs as sound absorbing materials has been proven.