Sol–gel preparation and characterization of Bi4(Si1−xGex)3O12 solid solutions

Micro-crystals of Bi₄(Ge_xSi_1?x)₃O₁₂ (x = 0, 0.25, 0.5, 0.75, 1) solid solution series were synthesized by a sol–gel method, using stoichiometric Si(OC₂H₅)₄, GeO₂, Bi(NO₃)₃·5H₂O as the starting materials. The as-prepared series were studied by X-ray diffraction, Raman spectra, differential thermal analysis, and fluorescence spectra. Experiments showed that single phase of Bi₄(Si_1?xGe_x)₃O₁₂ was obtained by the sol–gel method. For all the composition, Bi₄Si₃O₁₂ and Bi₄Ge₃O₁₂ can completely dissolve into each other. The refined cell parameters were in proportion to the composition. Bi₄Ge₃O₁₂ showed the strongest fluorescence emission while Bi₄Si₃O₁₂ showed the weakest fluorescence emission.     

Synthesis of molecularly imprinted polymer nanoparticles for the fast and highly selective adsorption of sunset yellow

Novel molecularly imprinted polymer nanoparticles were synthesized by precipitation polymerization with sunset yellow as the template and [2‐(methacryloyloxy)ethyl] trimethylammonium chloride as the functional monomer. The molecularly imprinted polymer nanoparticles were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and their specific surface area and thermal stability were measured. The molecularly imprinted polymer nanoparticles had a high adsorption capacity in wide pH range (pH 1–8) for sunset yellow. The adsorption equilibrium only needed 5 min, and the quantitative desorption was very fast (1 min) by using 10.0 mol/L HCl as the eluant. The maximum adsorption capacity of the molecularly imprinted polymer nanoparticles for sunset yellow was 144.6 mg/g. The adsorption isotherm and kinetic were well consistent with Langmuir adsorption model and pseudo‐second‐order kinetic model, respectively. The relative selectivity coefficients of the molecularly imprinted polymer nanoparticles for tartrazine and carmine were 9.766 and 12.64, respectively. The prepared molecularly imprinted polymer nanoparticles were repeatedly used and regenerated ten times without significant absorption capacity decrease.     

微量进样-火焰原子吸收光谱法测定豚鼠内耳外淋巴液中钙、镁、钾、钠等元素含量

采用直接定量取样稀释、微量进样-火焰原子吸收光谱法测定了豚鼠内耳外淋巴液中Ca、Mg、K、Na等元素含量。方法简便、可靠，满足了生物样品测定的要求。     

互穿网络聚合物的某些进展

综述近年来热塑性互穿网络聚合物及以蓖麻油为原料合成的互穿网络聚合物的进展。     

Crystal structure and the standard molar enthalpy of formation of a coordination polymer [Cu(nip)(phen)]n

A coordination polymer [Cu(nip)(phen)]_n was hydrothermally synthesized by the reaction of Cu(NO₃)₂ with 5-nitroisophthalic acid and phen. Single-crystal structure analysis showed that the complex crystallized in the monoclinic space group P2₁/c; a = 10.6566(13); b = 12.5931(15); c = 13.0514(16) Å; β = 95.474(2)°, V = 1743.5(4) Å³; Z = 4. The standard molar enthalpy of formation of the complex was determined to be −554 ± 11 kJ mol⁻¹.     

Effect of PLGA as a polymeric emulsifier on preparation of hydrophilic protein-loaded solid lipid nanoparticles

Most proteins are hydrophilic and poorly encapsulated into the hydrophobic matrix of solid lipid nanoparticles (SLN). To solve this problem, poly (lactic-co-glycolic acid) (PLGA) was utilized as a lipophilic polymeric emulsifier to prepare hydrophilic protein-loaded SLN by w/o/w double emulsion and solvent evaporation techniques. Hydrogenated castor oil (HCO) was used as a lipid matrix and bovine serum albumin (BSA), lysozyme and insulin were used as model proteins to investigate the effect of PLGA on the formulation of the SLN. The results showed that PLGA was essential for the primary w/o emulsification. In addition, the stability of the w/o emulsion, the encapsulation efficiency and loading capacity of the nanoparticles were enhanced with the increase of PLGA concentration. Furthermore, increasing PLGA concentration decreased zeta potential significantly but had no influence on particle size of the SLN. In vitro release study showed that PLGA significantly affected the initial burst release, i.e. the higher the content of PLGA, the lower the burst release. The released proteins maintained their integrity and bioactivity as confirmed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and biological assay. These results demonstrated that PLGA was an effective emulsifier for the preparation of hydrophilic protein-loaded SLN.     

A chemically consistent graph architecture for massive reaction networks applied to solid-electrolyte interphase formation

Modeling reactivity with chemical reaction networks could yield fundamental mechanistic understanding that would expedite the development of processes and technologies for energy storage, medicine, catalysis, and more. Thus far, reaction networks have been limited in size by chemically inconsistent graph representations of multi-reactant reactions (e.g. A + B → C) that cannot enforce stoichiometric constraints, precluding the use of optimized shortest-path algorithms. Here, we report a chemically consistent graph architecture that overcomes these limitations using a novel multi-reactant representation and iterative cost-solving procedure. Our approach enables the identification of all low-cost pathways to desired products in massive reaction networks containing reactions of any stoichiometry, allowing for the investigation of vastly more complex systems than previously possible. Leveraging our architecture, we construct the first ever electrochemical reaction network from first-principles thermodynamic calculations to describe the formation of the Li-ion solid electrolyte interphase (SEI), which is critical for passivation of the negative electrode. Using this network comprised of nearly 6000 species and 4.5 million reactions, we interrogate the formation of a key SEI component, lithium ethylene dicarbonate. We automatically identify previously proposed mechanisms as well as multiple novel pathways containing counter-intuitive reactions that have not, to our knowledge, been reported in the literature. We envision that our framework and data-driven methodology will facilitate efforts to engineer the composition-related properties of the SEI – or of any complex chemical process – through selective control of reactivity.

A chemically consistent graph architecture enables autonomous identification of novel solid-electrolyte interphase formation pathways from a massive reaction network.     

The solvability conditions for the inverse eigenproblems of symmetric and generalized centro-symmetric matrices and their approximations

Let ∥ · ∥ be the Frobenius norm of matrices. We consider (I) the set S_E of symmetric and generalized centro-symmetric real n × n matrices R_n with some given eigenpairs (λ_j, q_j) (j = 1, 2, … , m) and (II) the element in S_E which minimizes for a given real matrix R^∗. Necessary and sufficient conditions for S_E to be nonempty are presented. A general form of elements in S_E is given and an explicit expression of the minimizer is derived. Finally, a numerical example is reported.     

强流柱对称相对论电子束的势能与发射度

推导了柱对称相对论电子束在漂移管内的空间电荷势及相互作用势能,分析了势能在束流传输过程中的变化规律,并与束流均方根发射度的变化方程比较。指出一部分势能随束流传输过程中包络振荡而呈现出可逆的变化;而另一部分势能则在束流传输系统及束流本身非线性力的作用下,随着电荷密度分布变化而转为电荷横向热运动能量,从而导致束流归一化发射度的增长,这种转化是一个不可逆的过程。     

Development of a magnetic solid‐phase extraction coupled with high‐performance liquid chromatography method for the analysis of polyaromatic hydrocarbons

A novel magnetic solid phase extraction coupled with high‐performance liquid chromatography method was established to analyze polyaromatic hydrocarbons in environmental water samples. The extraction conditions, including the amount of extraction agent, extraction time, pH and the surface structure of the magnetic extraction agent, were optimized. The results showed that the amount of extraction agent and extraction time significantly influenced the extraction performance. The increase in the specific surface area, the enlargement of pore size, and the reduction of particle size could enhance the extraction performance of the magnetic microsphere. The optimized magnetic extraction agent possessed a high surface area of 1311 m²/g, a large pore size of 6–9 nm, and a small particle size of 6–9 μm. The limit of detection for phenanthrene and benzo[g,h,i]perylene in the developed analysis method was 3.2 and 10.5 ng/L, respectively. When applied to river water samples, the spiked recovery of phenanthrene and benzo[g,h,i]perylene ranged from 89.5–98.6% and 82.9–89.1%, respectively. Phenanthrene was detected over a concentration range of 89–117 ng/L in three water samples withdrawn from the midstream of the Huai River, and benzo[g,h,i]perylene was below the detection limit.