大豆脲酶诱导碳酸钙沉淀的多因素影响分析

本文探究了多个影响因素对大豆脲酶诱导碳酸钙沉淀(SICP)的影响,以优选出主要影响因素并提供其最佳范围。首先分析了脲酶浓度和温度对脲酶活性的影响;之后通过正交实验设计,进行25种工况的SICP水溶液实验,研究不同因素组合下Ca²⁺利用率的变化规律;最后借助扫描电子显微镜观测不同工况下生成碳酸钙的形态。结果表明:低温有利于脲酶的保存及活性发挥,5 ℃时脲酶活性能保持21 d以上;同一温度下,脲酶浓度越大,脲酶初始活性越高,脲酶完全失活所需时间越短。pH值、脲酶与胶结液体积比是影响Ca²⁺利用率的主要因素。为达到较高的Ca²⁺利用率,脲酶和胶结液最佳体积比为1,氯化钙与尿素最佳浓度比为1.5,Ca²⁺最佳浓度为1 mol/L。当脲酶浓度较低时生成的六面体状碳酸钙较多;随着脲酶浓度的增大,所沉淀的碳酸钙向球形转变。大豆中富含的天冬氨酸是控制碳酸钙形态的重要因素。     

Synergistic therapeutic effects of Duzhong Jiangya Tablets and amlodipine besylate combination in spontaneously hypertensive rats using 1H-NMR- and MS-based metabolomics

Duzhong Jiangya Tablet (DJT) composed of Eucommia ulmoides Oliv. and several other traditional Chinese medicines is a Chinese herbal compound, which is clinically used to treat hypertension. The aim of this study was to evaluate the antihypertensive effect of DJT and amlodipine besylate (AB) on the synergistic treatment of spontaneously hypertensive rats (SHRs), and to explore its antihypertensive mechanism. The synergistic therapeutic effect of DJT in combination with AB on SHR was studied using two metabolomics methods based on mass spectrum (MS) and nuclear magnetic resonance. Metabolomics analysis of plasma, urine, liver, and kidney and the combination of orthogonal partial least squares discriminant analysis was performed to expose potential biomarkers. Then, the overall metabolic characteristics and related abnormal metabolic pathways in hypertensive rats were constructed. Blood pressure measurements showed that DJT combined with AB has better effects in treating hypertension than it being alone. A total of 30 biomarkers were identified, indicating that hypertension disrupted the balance of multiple metabolic pathways in the body, and that combined administration restored metabolite levels better than their administration alone. The changes of biomarkers revealed the synergistic therapeutic mechanism of DJT combined with AB, which provided a reference for the combination of Chinese and Western medicines.     

Design and development of self-repairable and recyclable crosslinked poly(thiourethane-urethane) via enhanced aliphatic disulfide chemistry

Thermoset polymer elastomers that are capable of autonomous repairability upon physical damage at ambient temperature are highly desirable because of their thermal and environmental resistance, outstanding mechanical toughness and stability. To aim at this goal, we demonstrated that tris(diethylamino)phosphine was initially proven as an efficient catalyst for the aliphatic disulfide exchange at mild condition. By making use of the aliphatic disulfide bond reshuffling and elasticity of polyurethane elastomers, the inherently cross-linked polysulfide-based poly(thiourethane-urethane) elastomers were prepared and exhibited the ability to mend without extrinsic stimuli in the presence of phosphorus catalyst at room temperature after artificially damaged. The self-healing efficiency via the mechanical recovery approach was investigated to be mainly dependent upon the cross-linking density of polysulfide and hard segments chemistry, which in turns determined the molecular chain diffusion and reshuffling that was corroborated by the stress-relaxation study. The thermoset elastomer based on asymmetric diisocynate showed a maximum self-healing efficiency of 85.6% compared to 71.6% for the elastomer with symmetric monomer building blocks. The self-healable polymer was confirmed to be recyclable and reprocessable through a cut-compression processing cycle under a quite mild pressure and temperature thanks to the disulfide bond reshuffling. Meanwhile, the recycled thermoset elastomer well maintained the mechanical properties to its original material.     

Comparative Study of the Supercapacitive Performance of Three Ferrocene-Based Structures: Targeted Design of a Conductive Ferrocene-Functionalized Coordination Polymer as a Supercapacitor Electrode

As redox-active based supercapacitors are known as highly desirable next-generation supercapacitor electrodes, the targeted design of two ferrocene-functionalized (Fc(COOH)₂) clusters based on coinage metals, [(PPh₃)₂AgO₂CFcCO₂Ag(PPh₃)₂]₂ ⋅ 7 CH₃OH (SC₁: super capacitor) and [(PPh₃)₃CuO₂CFcCO₂Cu(PPh₃)₃] ⋅ 3 CH₃OH (SC₂), is reported. Both structures are fully characterized by various techniques. The structures are utilized as energy storage electrode materials, giving 130 F g⁻¹ and 210 F g⁻¹ specific capacitance at 1.5 A g⁻¹ in Na₂SO₄ electrolyte, respectively. The obtained results show that the presence of Cu^I instead of Ag^I improves the supercapacitive performance of the cluster. Further, to improve the conductivity, the PSC₂ ([(PPh₃)₂CuO₂CFcCO₂]_∞), a polymeric structure of SC₂, was synthesized and used as an energy storage electrode. PSC₂ displays high conductivity and gives 455 F g⁻¹ capacitance at 3 A g⁻¹. The PSC₂ as a supercapacitor electrode presents a high power density (2416 W kg⁻¹), high energy density (161 Wh kg⁻¹), and long cycle life over 4000 cycles (93 %). These results could lead to the amplification of high-performance supercapacitors in new areas to develop real applications and stimulate the use of the targeted design of coordination polymers without hybridization or compositions with additive materials.     

Purification of low-abundance lysozyme in egg white via free-flow electrophoresis with gel-filtration chromatography

As an effective separation tool, free-flow electrophoresis has not been used for purification of low-abundance protein in complex sample matrix. Herein, lysozyme in complex egg white matrix was chosen as the model protein for demonstrating the purification of low-content peptide via an FFE coupled with gel fitration chromatography (GFC). The crude lysozyme in egg while was first separated via free-flow zone electrophoresis (FFZE). After that, the fractions with lysozyme activity were condensed via lyophilization. Thereafter, the condensed fractions were further purified via a GFC of Sephadex G50. In all of the experiments, a special poly(acrylamide- co-acrylic acid) (P(AM-co-AA)) gel electrophoresis and a mass spectrometry were used for identification of lysozyme. The conditions of FFZE were optimized as follows: 130 μL/min sample flow rate, 4.9 mL/min background buffer of 20 mM pH 5.5 Tris-Acetic acid, 350 V, and 14 °C as well as 2 mg/mL protein content of crude sample. It was found that the purified lysozyme had the purity of 80% and high activity as compared with its crude sample with only 1.4% content and undetectable activity. The recoveries in the first and second separative steps were 65% and 82%, respectively, and the total recovery was about 53.3%. The reasons of low recovery might be induced by diffusion of lysozyme out off P(AM-co-AA) gel and co-removing of high-abundance egg ovalbumin. All these results indicated FFE could be used as alternative tool for purification of target solute with low abundance.     

Thionylimido Complexes

An improved route to d-block and main group NSO complexes is presented including the synthesis of the first antimony(V) complexes, (Ar₃Sb(NSO)₂), and copper examples [CuBipy(PPh₃)NSO]. The structures of eight complexes are reported. The observed variation in M–N–S bond angles is due to the combination of orbital overlap (ligand-to-metal bonding) and the degree of ionicity of the bonding.