黄油中8种类固醇激素的液相色谱/串联质谱检测

建立了黄油中雌酮、α-雌二醇、β-雌二醇、雌三醇、睾酮、表睾酮、孕酮和丙酸睾酮8种类固醇激素的凝胶渗透色谱(GPC)-液相色谱/串联质谱(LC-MS/MS)检测方法。样品用乙酸乙酯-环己烷(1∶1,V/V)提取,提取液经GPC柱净化除脂,GPC浓缩液采用C18色谱柱(100 mm×2.0 mm i.d.,3.0μm)分离,以乙腈和水为流动相进行梯度洗脱,电喷雾电离多反应监测模式进行定性和定量分析。8种类固醇激素以基质匹配外标法定量,药物在1.0~20.0μg/kg线性范围内相关系数(r)均大于0.999;方法检出限(S/N=3)为0.04~0.30μg/kg,定量限LOQs(S/N=10)为1.0μg/kg;添加水平为1.0,2.0,4.0μg/kg时,回收率范围在64.1%~110%之间;相对标准偏差(RSD)小于11%。结果表明,本方法准确、可靠,满足黄油中8种类固醇激素的检测分析要求。     

加速溶剂萃取-多层硅胶柱净化-气相色谱串联三重四级杆质谱法测定土壤和沉积物中的多氯萘

通过制作多氯萘(PCNs)在商品多层硅胶柱上的流出曲线、优化气相色谱质谱参数和利用三重四级杆质谱的多重反应监测模式,应用氘代一氯萘#2作为一氯和二氯代萘的定量内标,建立了基于DB-5MS和Rt-βDEXcst两根色谱柱的同位素稀释测定土壤和沉积物中多氯萘的分析方法,实现了两种高毒性六氯代萘#66和#67的基线分离。18种多氯萘同类物校正曲线在1.0~240μg/L浓度范围的相对响应因子为0.70~5.45,相对标准偏差小于18.5%。方法检出限在0.014~0.858μg/L之间,定量限在0.048~2.862μg/L之间。30 m的Rt-βDEXcst色谱柱方法效果优于60 m的DB-5MS色谱柱,但前者耗时较长。实际样品分析表明,7种PCNs回收率标记物,除一氯代萘约为6%外,其余均大于28%。测试土壤和沉积物样品中以低氯代萘为主。     

N2/Ar等离子体改性对CuO/TiO2可见光光催化活性的影响

研究了N2/Ar介质阻挡放电处理对负载CuO的TiO2可见光光催化活性的影响.采用X射线衍射、紫外-可见分光吸收光谱、透射电镜、X射线光电子能谱和电子自旋共振进行了表征,详细考察了等离子改性参数包括气氛组成、处理时间和处理功率对改性效果的影响,并通过降解甲基橙溶液考察了可见光光催化活性.结果表明,最佳等离子处理条件为N2与Ar比例为8:2,处理时间为20 min,放电电流为1.0 A.最后,使用改性后的光催化剂对模拟含汞废水进行了处理.     

Vulcanization kinetics of graphene/styrene butadiene rubber nanocomposites

This paper presents the influence of graphene on the vulcanization kinetics of styrene butadiene rubber （SBR） with dicumyl peroxide. A curemeter and a differential scanning calorimeter were used to investigate the cure kinetics, from which the kinetic parameters and apparent activation energy were obtained. It turns out that with increasing graphene loading, the induction period of the vulcanization process of SBR is remarkably reduced at low graphene loading and then levels off; on the other hand, the optimum cure time shows a monotonous decrease. As a result, the vulcanization rate is suppressed at first and then accelerated, and the corresponding activation energy increases slightly at first and then decreases. Upon adding graphene, the crosslinking density of the nanocomposites increases, because graphene takes part in the vulcanization process.     

Effect of Cofactor Folate on the Growth of Corynebacterium glutamicum SYPS-062 and l-Serine Accumulation

The direct fermentative production of l-serine from sugar has attracted increasing attention. Corynebacterium glutamicum SYPS-062 can directly convert sugar to l-serine. In this study, the effects of exogenous and endogenous regulation of cofactor folate on C. glutamicum SYPS-062 growth and l-serine accumulation were investigated. For exogenous regulation, the inhibitor (sulfamethoxazole) or precursor (p-aminobenzoate) of folate biosynthesis was added to the medium, respectively. For endogenous regulation, the gene (pabAB) that encodes the key enzyme of folate biosynthesis was knocked out or overexpressed to obtain the recombinant C. glutamicum SYPS-062 ΔpabAB and SYPS-062(pJC-tac-pabAB), respectively. The results indicated that decreased levels of cofactor folate supported l-serine accumulation, whereas increased levels of cofactor folate aided in cell growth of C. glutamicum SYPS-062. Thus, this study not only elucidated the role of folate in C. glutamicum SYPS-062 growth and l-serine accumulation, but also provided a novel and convenient approach to regulate folate biosynthesis in C. glutamicum.     

Landfill leachate treatment using the sequencing batch biofilm reactor method integrated with the electro-Fenton process

A study was conducted on the treatment of landfill leachate by combining the sequencing batch biofilm reactor (SBBR) method with the electro-Fenton method. The reduction of chemical oxygen demand (COD), biological oxygen demand (BOD₅), and ammonia nitrogen (NH ₄ ⁺ -N) from the leachate by the SBBR method was investigated. For the electro-Fenton experiment, the changes in COD and total organic carbon (TOC) with the increase in H₂O₂ dosage and electrolysis time under optimal conditions were also analysed. The results showed that the average efficiencies of reduction of COD, BOD₅, and NH ₄ ⁺ -N achieved using the SBBR method were 21.6 %, 54.7 %, and 56.1 %, respectively. The bio-effluent was degraded by the subsequent electro-Fenton process, which was rapid over the first 30 min then subsequently slowed. After 60 min of the electro-Fenton treatment, the efficiencies of reduction of TOC, COD, and BOD₅ were 40.5 %, 71.6 %, and 61.0 %, respectively. There is a good correlation between the absorbance of leachate at 254 nm (UV₂₅₄) and COD or TOC during the electro-Fenton treatment.     

CO2 sorption in wet ordered mesoporous silica kit-6: effects of water content and mechanism on enhanced sorption capacity

The sorption isotherms of CO₂ in wet ordered mesoporous silica KIT-6 with different amounts of pre-adsorbed water were firstly collected experimentally using a volumetric method in the temperature range of 275–281 K. The isotherms show an inflection point indicating CO₂ hydrates form in the pore spaces which is proofed by the enthalpy change calculated at the inflection pressure, and the quantity of water content shows considerable effect on the sorption capacity of CO₂. The highest enhancement of sorption capacity in the presence of water is observed in wet KIT-6 sample with water loadings of 2.48, which is about 12.80 mmol/g and 1.86 times than that on dry sample. However, the saturation capacity is still far less than that what can be stored merely in the form of hydrates due to the low ratio of water utilization because of the large pore and the polar surface of KIT-6.     

Three dimension Liesegang rings of calcium hydrophosphate in gelatin

Three dimensional Liesegang spherical layers of CaHPO₄ in gelatin ball were performed by employing CaCl₂ and Na₂HPO₄ as the inner and outer electrolyte, respectively. Effects of concentrations of inner and outer electrolyte as well as pH on the morphologies of Liesegang rings (LRs) were investigated. As a result, it was observed that the time law, spacing law and width law found in 1D/2D gel systems were obeyed in this 3D gelatin system. The interaction of Ca²⁺ and HPO₄ ^2? with gelatin matrix played a key role to the formation of LRs due to the existence of carboxylic groups on the gelatin chains. Using Ca²⁺ as the inner electrolyte, LRs were prepared. However, employing HPO₄ ^2? as inner electrolyte, LRs were not obtained. Moreover, pH of gelatin solution greatly impacted on the formation of LRs. The number of LRs increased with the decrease of pH, whereas the width inversely decreased. pH 4.40 was a turn point, from which the spacing coefficient abruptly increased as pH increased. All these results indicated that the network was created by the interaction of Ca²⁺ and –COO^? of gelatin chains, which dominated the formation of CaHPO₄ LRs in gelatin.     

Microwave sintering of nickel ferrite nanoparticles processed via sol–gel method

Magnetic nickel ferrite (NiFe₂O₄) was prepared by sol–gel process and calcined in the 2.45 GHz singlemode microwave furnace to synthesize nickel nanopowder. The sol–gel method was used for the processing of the NiFe₂O₄ powder because of its potential for making fine, pure and homogeneous powders. Sol–gel is a chemical method that has the possibility of synthesizing a reproducible material. Microwave energy is used for the calcining of this powder and the sintering of the NiFe₂O₄ samples. Its use for calcination has the advantage of reducing the total processing time and the soak temperature. In addition to the above combination of sol–gel and microwave processing yields to nanoscale particles and a more uniform distribution of their sizes. X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy and vibrating sample magnetometer were carried out to investigate structural, elemental, morphological and magnetic aspects of NiFe₂O₄. The results showed that the mean size and the saturation magnetization of the NiFe₂O₄ nanoparticles are about 30 nm and 55.27 emu/g, respectively. This method could be used as an alternative to other chemical methods in order to obtain NiFe₂O₄ nanoparticles.     

毛细管电泳电化学发光法分离测定奶粉中的二聚氰胺和三聚氰胺

基于二聚氰胺和三聚氰胺在Pt盘电极上对Ru(bpy)2+3的发光有增敏效果,建立了毛细管电泳电化学发光法同时分离检测乳制品中二聚氰胺和三聚氰胺的含量的新方法。进行实验条件优化,采用5 mmol/L Ru(bpy)32++60 mmol/L pH 8.5磷酸缓冲液,10 kV×10 s电动进样,光电倍增管高压为900 V,检测电位为1.18V,分离电压为12 kV,使得二聚氰胺和三聚氰胺得到了很好的分离检测,对奶粉样品进行添加回收率实验,二聚氰胺和三聚氰胺的回收率分别为94.6%~97.8%和95.9%~97.4%,相对标准偏差分别为3.2%~4.6%和2.7%~4.1%。