微溶剂萃取-气相色谱-质谱法测定水中邻苯二甲酸二(2-乙基己基)酯

取水样25mL,加入无水硫酸钠3.0g,加入环己烷2.0mL,振荡萃取3min。移取萃取了邻苯二甲酸二(2-乙基己基)酯(DEHP)的上层有机相2.0μL注入HP-5毛细管柱(30m×0.32mm,0.25μm)色谱分离后进行质谱测定。DEHP的质量浓度在50.0μg.L-1以内与其峰面积呈线性关系,方法的检出限(3S/N)为0.052μg.L-1。分析了早、中、晚不同时间的天津市自来水,并用标准加入法做回收试验,测得回收率在97.0%～109.4%之间,测定值的相对标准偏差(n=6)均小于2.5%。     

离子交换色谱法测定小球藻提取物中的核苷酸

建立了用阴离子交换色谱法测定小球藻提取物中的各种核苷酸的方法。用Shim PackWAX 1色谱柱 (5 0mm× 4 .6mmi.d .,粒度 3μm ,孔径 1 0 0nm) ,2 5mmol/L的磷酸二氢钠水溶液 (pH =3.5 ) ,流量梯度洗脱。检测波长 2 6 0nm。回收率在 97.5 0 %～ 99.4 0 %。该法简便 ,灵敏 ,重现性好 ,可以广泛应用于各类小球藻提取物和各类食品中的核苷酸的检测     

Micellization of anionic gemini surfactants and their interaction with polyacrylamide

A series of anionic gemini surfactants have been synthesized. The surface properties and micellization process of as-prepared sulfonate gemini surfactants (SGS) and carboxylate gemini surfactant (CGS) have been studied by surface tension measurement and isothermal titration microcalorimetry. Meanwhile, the interaction of these five surfactants with polyacrylamide (PAM) was investigated using surface tension, steady-state fluorescence measurement, and isothermal titration microcalorimetry. The results show that the critical micelle concentrations (CMCs) of above-mentioned surfactants are more than 1 order of magnitude lower than those of corresponding single chain surfactants. Moreover, the enthalpy of micelle formation (ΔH _mic) for the investigated gemini surfactants is negative. In the surfactant–PAM systems, the thermodynamic parameters of binding have also been determined. The conclusion may be drawn that the binding strength of SGS onto PAM is stronger than that of CGS, resulting from more compact structure of SGS aggregates. With increasing surfactant hydrophobicity, the values of ΔH _agg become more exothermic and a ΔS _agg decrease was observed. Therefore, the interaction between SGS and PAM is enthalpy-driven.     

Experimental Evidence for a Triboluminescent Antiperovskite Ferroelectric: Tris(trimethylammonium) catena‐Tri‐μ‐chloro‐manganate(II) Tetrachloromanganate(II)

The perovskite structure is rich in ferroelectricity. In contrast, ferroelectric antiperovskites have been scarcely confirmed experimentally since the discovery of M₃AB‐type antiperovskites in the 1930s. Ferroelectricity is now revealed in an organic–inorganic hybrid X₃AB antiperovskite structure, which exhibits a clear ferroelectric phase transition 6/mmmF6mm with a high Curie point of 480 K. The physical properties across the phase transition are obviously changed along with the symmetry requirements, providing solid experimental evidence for the ferroelectric phase transition. More interestingly, the discovered antiperovskite shows intense photoluminescence and triboluminescence properties. The confirmation of the triboluminescent ferroelectric antiperovskite will open new avenues to explore excellent optoelectronic properties in the antiperovskite family.     

Stress‐Transfer‐Induced In Situ Formation of Ultrathin Nickel Phosphide Nanosheets for Efficient Hydrogen Evolution

Ultrathin two‐dimensional (2D) nanostructures have attracted increasing research interest for energy storage and conversion. However, tackling the key problem of lattice mismatch inducing the instability of ulreathin nanostructures during phase transformations is still a critical challenge. Herein, we describe a facile and scalable strategy for the growth of ultrathin nickel phosphide (Ni₂P) nanosheets (NSs) with exposed (001) facets. We show that single‐layer functionalized graphene with residual oxygen‐containing groups and a large lateral size contributes to reducing the lattice strain during phosphorization. The resulting nanostructure exhibits remarkable hydrogen evolution activity and good stability under alkaline conditions.     

The influence of nanoparticle shape on bilateral exocytosis from Caco-2 cells

Nanoparticles are able to be excreted from both apical and basolateral sides after taken up by cells. Compared to nanospheres, nanorods preferred basolateral exocytosis to apical exocytosis.     

Modification of the Extended UNIQUAC Model to Study the Phase Behavior of the [Bmim]Cl–K<Subscript>2</Subscript>HPO<Subscript>4</Subscript> Aqueous Two Phase System at 298.15 K

Aqueous two phase systems (ATPS), consisting of two incompatible aqueous solutions, are widely used in biological extraction. In recent years, many experimental studies on the phase behavior of ionic liquid(IL)–inorganic salt ATPS systems have been reported but few investigations of the thermodynamics of the IL-based ATPS have been reported. In this work, the Extended UNIQUAC model is modified to calculate the equilibrium of [Bmim]Cl–K₂HPO₄–H₂O ATPS at 298.15 K. All the interaction parameters of the model are salt specific. The results show that the experimental compositions of tie lines are correlated successfully using the proposed model. The root mean square deviation of the mass fraction is 0.0256.     

Biosynthetic approach to modeling and understanding metalloproteins using unnatural amino acids

Metalloproteins have inspired chemists for many years to synthesize artificial catalysts that mimic native enzymes.As a complementary approach to studying native enzymes or making synthetic models,biosynthetic approach using small and stable proteins to model native enzymes has offered advantages of incorporating non-covalent secondary sphere interactions under physiological conditions.However,most biosynthetic models are restricted to natural amino acids.To overcome this limitation,incorporating unnatural amino acids into the biosynthetic models has shown promises.In this review,we summarize first synthetic,semisynthetic and biological methods of incorporates unnatural amino acids(UAAs)into proteins,followed by progress made in incorporating UAAs into both native metalloproteins and their biosynthetic models to fine-tune functional properties beyond native enzymes or their variants containing natural amino acids,such as reduction potentials of azurin,O_2 reduction rates and percentages of product formation of HCO models in Mb,the rate of radical transport in ribonucleotide reductase(RNR)and the proton and electron transfer pathways in photosystemⅡ(PSⅡ).We also discuss how this endeavour has allowed systematic investigations of precise roles of conserved residues in metalloproteins,such as Metl21 in azurin,Tyr244 that is cross-linked to one of the three His ligands to CuB in HCO,Tyr122,356,730 and 731 in RNR and TyrZ in PSⅡ.These examples have demonstrated that incorporating UAAs has provided a new dimension in our efforts to mimic native enzymes and in providing deeper insights into structural features responsible high enzymatic activity and reaction mechanisms,making it possible to design highly efficient artificial catalysts with similar or even higher activity than native enzymes.