Kinetic characterization of the interactions of trans-dichloro-platinum(IV) anticancer prodrugs and a model compound with thiosulfate

Sodium thiosulfate has been utilized as a rescuing agent for relief of the toxic effects of cisplatin and carboplatin. In this work, we characterized the kinetics of reactions of the trans-dichloro-platinum(IV) complexes cis-[Pt(NH₃)₂Cl₄], ormaplatin [Pt(dach)Cl₄] and trans-[PtCl₂(CN)₄]^2? (anticancer prodrugs and a model compound) with thiosulfate at biologically important pH. An overall second-order rate law was established for the reduction of trans-[PtCl₂(CN)₄]^2? by thiosulfate, and varying the pH from 4.45 to 7.90 had virtually no influence on the reaction rate. In the reactions of thiosulfate with cis-[Pt(NH₃)₂Cl₄] and with [Pt(dach)Cl₄], the kinetic traces displayed a fast reduction step followed by a slow substitution involving the intermediate Pt(II) complexes. The reduction step also followed second-order kinetics. Reductions of cis-[Pt(NH₃)₂Cl₄] and [Pt(dach)Cl₄] by thiosulfate proceeded with similar rates, presumably due to their similar configurations, whereas the reduction of trans-[PtCl₂(CN)₄]^2? was about 1,000 times faster. A common reduction mechanism is suggested, and the transition state for the rate-determining step has been delineated. The activation parameters are consistent with transfer of Cl⁺ from the platinum(IV) center to the attacking thiosulfate in the rate-determining step.     

DyxTbyY1-x-yP5O14晶体的荧光性质

研究了DyxTbgY1-x-yP5O14晶体的荧光特征,Dy3+离子对Tb3+离子5D3能级的猝灭作用和对5D4能级的敏化作用,讨论了Tb3+离子和Dy3+离子浓度间的关系及对荧光强度和荧光寿命的影响。     

PM晶体声光混合型光学双稳态原理设计及频率反馈网络系统研究

本文简介PbMoO₃混合型光学双稳态的原理设计及其反馈网络系统的装置。通过实验及调节,测试了该器件的衍射曲线,反馈曲线以及光学双稳滞后回线。实践证明:PbMoO₃声光晶体具有良好的光学双稳特性,可以作为多通道开关,适用于波导技术。     

毛细管电泳技术在疾病预防控制领域的应用、发展与挑战

自1989年出现商品化的仪器以来,毛细管电泳（CE）技术在多个应用领域都取得了长足的进步与发展,重复性和准确性方面也有很大提升。能力验证样品分析的满意结果也显示了CE具备法规要求的准确定量能力。在疾病预防控制领域（简称"疾控"）CE也展现出很多独具特色的应用,成为不可或缺的技术之一。在聚合酶链式反应产物分析、核酸序列测定、DNA变异和分型分析、食源性致病微生物分析及疫苗分析等工作中CE发挥了重要作用。应对突发疫情或公共卫生事件如食物中毒时,除了通过非靶标分析尽快锁定目标物外,还需要对大量样品做出快速而准确的分析,高通量和高灵敏的CE就十分适合解决这一问题。在公共卫生理化检验以确保食品、保健食品、特殊医学用途食品、化妆品和消毒产品等的安全中,CE也发挥了不可或缺的作用。作为一种使用较少危险化学品的环境友好方法,在需要按照标准或规范进行的疾控实验室常规检测中,CE仍受制于标准方法的缺失,未能发挥其应有的作用。但简单、快速、经济、耐用、高效的CE分离一旦与高灵敏通用检测器联用,必将更加从容地应对疾控领域中的各种挑战,发挥更大的作用。本文综述了2010~2019年CE在疾控领域的应用,分析了CE在疾控领域发展的机遇和挑战,对CE在疾控领域的发展前景进行了展望。     

Novel biomarkers of protein oxidation sites and degrees using horse cytochrome c as the target by mass spectrometry

Biomarkers held both incredible application and significant challenge in probing the oxidation mechanisms of proteins under oxidative stress. Here, mass spectrometry (MS) coupled with liquid chromatography (LC) was applied to establish a new pipeline to probe the oxidation sites and degrees of horse cytochrome c (HCC) with its oxidative products serving as the biomarkers. Samples of native and UV/H(2)O(2) oxidized HCCs were digested by trypsin and subjected to biomarker discovery using LC/MS and tandem mass spectrometry (MS/MS). Experiment results proved that the main oxidation sites were located at Cys(14), Cys(17), Met(65) and Met(80) residues in peptides C(14)AQC(heme)HTVEK(22), C(14)AQCHTVEK(22), E(60)ETLMEYLENPKK(73), M(80)IFAGIK(86) and M(80)IFAGIKK(87). Quantitative analysis on the oxidized peptides showed the oxidation degrees of target sites had positive correlations with extended oxidation dose and controlled by residues types and their accessibility to solvent molecules. Being able to provide plentiful information for the oxidation sites and oxidation degrees, the identified oxidized products were feasibility biomarkers for HCC oxidation, compared with the conventional protein carbonyl assay.     

Elevated ductility,optical, and air barrier properties of poly (butyleneadipate‐co‐terephthalate) bio‐based films via novel thermoplastic starch feature

It is important to develop high performances biodegradable polymers to eliminate the “white pollution” evoked by petroleum‐based polymer. Thermoplastic starch (TPS) with nano‐ellipse configuration was fabricated to reinforce the performances of poly (butylene adipate co‐terephthalate) (PBAT) biocomposites. Effects of tartaric acid (TA) (0.5% wt) on the structure of TPS and compatibility for PBAT were evaluated by Fourier‐transform infrared spectroscopy (FTIR), viscosity and rheological measurement, dynamic mechanical analysis (DMA) and scanning electron microscope (SEM), respectively. They revealed that TA reduced the molecular weight of starch and shear viscosity of TPS were beneficial for TPS dispersing in PBAT matrix with 184‐nm averaged diameter. PBAT/TPS‐TA (70:30 wt%) biocomposite films were blew with different blow‐up ratio. The morphology of films presented that nano‐TPS‐TA wrapped in the PBAT matrix and deformed from ball to capsule feature without agglomeration. Compared with those of PBAT film, the increment in elongation at break of PBAT/TPS‐TA film was 100%. The air permeability and UV‐VIS transmittance of PBAT/TPS‐TA films decreased from 6.92 × 10^?9 to 3.72 × 10^?9 cm³·cm·cm^?2 s^?1 Pa^?1 and 47.6% to 23.5%, respectively. This study proposed a facile approach to fabricate low‐cost PBAT films with significant improved mechanical, optical, and air barrier properties for commercial application. Mechanism for nanoparticles of TPS‐TA motivated the elevated performances was proposed, synchronously.     

Ce(VI)与6种天然黄酮化合物的氧化还原体系及其应用

选取结构相近的6种天然黄酮化合物：槲皮素(Quercetin)、山奈酚(Kaempferol)、木犀草素(Luteolin)、柚皮素(Naringenin)、黄芩素（Baicalein）和芹菜素（Apigenin）,利用紫外可见分光光度法,结合微量滴定手段,追踪并记录了6种黄酮化合物与Ce(Ⅳ)形成的氧化还原体系的紫外吸收信号,根据化合物对Ce(Ⅳ)响应差异,探讨了不同位置酚羟基对化合物抗氧化活性的贡献及作用机制。 结果表明,色原酮C环上3-OH首先与Ce(Ⅳ)作用,发生质子解离而氧化,其氧化产物在294 nm产生较强的吸收峰,3′,4′邻位-OH有利于在氧化剂Ce(Ⅳ)存在时4′羟基解离形成分子内氢键,紫外吸收光谱带Ⅱ的双峰会明显分离。 其它位置的酚羟基也会对Ce(Ⅳ)产生响应,且C环上的羟基比A环上的更灵敏。 同时,低浓度的黄酮会引起Ce(Ⅳ)的吸光度明显降低,由此得出6种化合物抗氧化能力顺序为Quercetin＞aempferol＞Luteolin＞Apigenin＞Baicalein＞Naringenin,与化合物的紫外吸收光谱响应灵敏度一致。     

Fuzzy clustering of paddy field soils in South China

Various paddy field soils in South China were measured during the rice-growing season and numerous data were collected concerning soil composition, water content and soil strength. A similarity matrix of 16 samples was constructed, by means of which the soils were clustered at λ = 0.75 into four groups.     

聚合物固载Ni－Ag双金属催化剂Ⅱ．催化剂的催化性质

聚合物固载Ｎｉ┐Ａｇ双金属催化剂Ⅱ．催化剂的催化性质吴世华朱常英王连邦张松桢（南开大学化学系，天津３０００７１）关键词镍，银，聚合物固载金属催化剂，加氢，燃料电池电极溶剂化金属原子浸渍（ＳＭＡＩ）技术是制备聚合物负载零价金属催化剂的一个非常有用的方法...     

金属蒸气法制备聚合物固载Pd—Cu燃料电池电极

利用金属蒸气法制备了三种不同金属重量比的树脂固我及活性炭负载Pd－Cu双金属催化剂。透射电镜（TEM）和X射线衍射（XRD）测定结果表明催化剂中Pd—Cu已形成合金。合金粒度极小，平均直径小于5nm。树脂固载催化剂金属粒度远小于活性炭负载催化剂的金属粒度。X－射线光电子能谱（XPS）结果表示Pd和Cu均以零价态存在。极化曲线表明，树脂固载催化剂的电催化活性接近于相应的活性炭负载催化剂。