基于尿素电合成反应的电催化剂研究进展

尿素是一种重要的化工原料并作为氮源广泛应用于化肥生产。工业合成尿素由氮气加氢合成氨气以及氨气和二氧化碳转化为尿素两步实现,存在高能耗和高污染等问题。通过电催化碳氮偶联,将二氧化碳和氮源（氮气、硝酸根、亚硝酸根、一氧化氮等）转化为尿素,可直接跳过合成氨反应并在温和的反应条件下同时实现人工固氮和固碳。因此,尿素电合成技术不仅避免了高能耗和高污染,还能够实现惰性气体分子的高效利用,对于加快实现“碳达峰碳中和”战略有着重要的意义。本文聚焦尿素电合成这一前沿研究热点,结合领域内最新研究进展,首先介绍了不同电催化剂的设计策略及其催化机制,随后总结了电催化碳氮偶联合成尿素的反应机理,并对尿素电合成的后续研究方向进行了展望。     

耐尔蓝硫酸盐在核酸分子表面的长距组装及核酸的三波长共振光散射测定

在pH7.20～7.60及离子强度低于0.012的介质中,耐尔蓝硫酸盐(NBS)在核酸分子表面进行长距组装后,产生293.4nm、349.4nm和560.4nm的共振光散射(RLS)增强峰.根据RLS增强的Scatchard数据分析表明,NBS在小牛胸腺DNA、鱼精DNA和酵母RNA上的组装数分别是6.4、6.6和3.9,组装常数分别为7.1×10~6mol/L、4.6×10~6mol/L和1.7×10~6mol/L.应用三个波长处的RLS增强之和可以测定0～0.8mg/L的小牛胸腺DNA、鱼精DNA和0.20～0.60mg/L的酵母RNA,检测限分别是0.4、1.2和10.5μg/L.方法已成功的应用于合成样测定.     

苯乙烯类菁染料pH探针的合成与活细胞成像

合成了一个以苯乙烯类菁染料为母体的含胺类基团的pH荧光探针, 合成方法简单, 产物收率高, 提纯方便. 在乙醇-水体系中的性能测试结果表明, 随着pH值的降低, 其非质子化形态的吸收峰强度逐渐降低, 而质子化形式的长波长吸收峰强度逐渐升高, 长、短波长相差(Δλ)130 nm, 颜色由黄色变成粉红色, 利于可视观察; 探针在氨基呈非质子化形式时没有荧光, 氨基质子化后探针的荧光强度显著增强. 活细胞实验表明, 探针可以穿透细胞膜, 在细胞质内pH值偏低区域显示红色荧光, 可以用来定性探测酸性细胞器.     

31P-NMR研究白血病细胞系Molt-4细胞内pH

用31P-NMR建立了无损伤性测定人淋巴瘤白血病细胞系Molt-4细胞胞内pH的方法.Molt-4细胞的31P核磁共振谱由无机磷(Pi)、ATP等的共振峰组成.通过测定Molt-4细胞内Pi化学位移进而能间接确定细胞内的pH,细胞内无机磷(Pi)的化学位移对pH非常敏感,随pH变化而变化.Molt-4细胞内Pi峰的化学位移为5.65±0.08(n=3),计算得到细胞内pH值为6.68±0.05.31P核磁共振能在测定细胞胞内pH的同时,观测到细胞内多种含磷小分子代谢物,是一种无损伤研究细胞内pH及代谢的有效方法.     

金属硫氰酸根配合物FeHg(SCN)~4, MnHg(SCN)~4的合成、晶体结 构与非线性光 学性质的研究

合成了配合物晶体FeHg(SCN)~4和MnHg(SCN)~4。用单晶X射线衍射方法测定了这两个晶体的结构。以尿素为标准样品用粉末晶体倍频1064nm的Nd:YAG激光,测得其倍频光强度分别为:FeHg(SCN)~4,0.6倍于尿素;MnHg(SCN)~4,50倍于尿素,后者显示了作为新的非线性光学材料的发展前景。     

CTAB透性化酵母细胞生物催化合成(S)-(+)-3-羟基丁酸乙酯

 利用十六烷基三甲基溴化铵(CTAB)透性化啤酒酵母细胞中高活性的脱氢酶,借助于辅助底物乙醇和葡萄糖,对3-羰基丁酸乙酯(EOB)不对称还原合成(S)-(+)-3-羟基丁酸乙酯((S)-(+)-3-EHB)进行了研究. 结果表明,CTAB透性化酵母细胞中的醇脱氢酶和6-磷酸葡萄糖脱氢酶的活性分别比未经处理的酵母细胞高482倍和6.5倍. 在相同条件下,CTAB透性化细胞对EOB的还原比未经处理的酵母细胞快. 细胞浓度对反应有明显影响,当透性化酵母细胞浓度＜90 mg/ml时,(S)-(+)-3-EHB的产率和对映体过量值都较低; 当酵母细胞浓度≥90 mg/ml,在最佳进料速率、最适温度和pH条件下,振摇速度为125 r/min时, (S)-(+)-3-EHB的浓度达到最大值314 mmol/L. 在反应开始的6 h内,(S)-(+)-3-EHB的产率可达94%,对映体过量值≥98%,但24 h后产率和对映体过量值分别降低到85%和91%.     

基于纤维小体展示技术的酿酒酵母纤维素乙醇研究进展

利用联合生物加工工艺生产第二代燃料乙醇(纤维素乙醇)是国内外的研究热点.前期的研究结果表明,酿酒酵母分泌或展示非复合型纤维素酶体系的应用效果并不理想,而复合型纤维素酶体系(即纤维小体)因对纤维素的降解能力比非复合型纤维素酶体系更强,所以其在酿酒酵母细胞表面的组装研究受到越来越多的关注.目前,单支架和双支架纤维小体在酵母细胞表面的完全自组装以及多细胞协同参与的非完全自组装均已实现.纤维小体展示型酿酒酵母已能直接利用结晶型纤维素发酵生产乙醇,但由于降解模块的结构缺陷,纤维素乙醇的产量仍然偏低.本文对纤维小体的酵母展示技术及其在纤维素乙醇发酵中的应用研究进行了论述,并对该领域的发展方向进行了展望.     

人早幼粒白血病细胞HL-60胞内pH的31P核磁共振研究

建立了无损伤性测定HL-60细胞胞内pH的31P-NMR方法.细胞内无机磷(Pi)的化学位移对pH非常敏感,随pH变化而变化,通过测定其化学位移进而能间接确定细胞内的pH.HL-60细胞的31P核磁共振谱由Pi、ATP等的共振峰组成.根据Pi峰的化学位移对HL-60细胞内pH进行了测定.HL-60细胞内Pi峰的化学位移为5.78±0.01,计算得到细胞内pH值为6.16±0.01.31P核磁共振能在测定细胞胞内pH的同时,观测到细胞内多种含磷小分子代谢物, 是一种无损伤研究细胞内pH及代谢的有效方法.     

高效液相色谱法测定克鲁维酵母菊芋发酵液中的乙醇,糖和有机酸类代谢成分

建立了高效液相色谱法同时分析菊芋发酵液中的乙醇和有机酸的方法.采用HPLC有机酸分析柱, 流动相为0.01 mol/L H2SO4,流速为0.5 mL/min, 以紫外和示差折光检测器作为双通道检测手段,同时对克鲁维酵母菊芋发酵液中的柠檬酸、α-酮戊二酸、葡萄糖、丙酮酸、果糖、琥珀酸、乳酸、甘油、乙酸、乙醇进行了定量分析,本方法的回收率为95.8%～109.6%;RSD为0.33%～4.0%,结果表明,本方法简单、快速、准确,适用于监控克鲁维酵母发酵产物并指导整个发酵过程条件的优化.     

富铬酵母中铬的化学种态及结合形态研究

对富铬酵母中铬的化学种态进行了分析和初步探讨。在铬的化学种态测定中铬的使用离子交换和火焰原子吸收法测定了富铬酵母中的Ｃｒ（Ⅲ）,方法快速简便、定量回收,结果表明,总铬呈为１５８２μｇ／ｇ的富铬酵母中,无机态铬占１６％,其中Ｃｒ（Ⅲ）为２３２μｇ／ｇ,Ｃｒ（Ⅵ）为２４．５μｇ／ｇ。酵各过程中的８４％以上的无机铬化合物转化成有机铬。说明铬参与了酵母细胞的生物合成,促进生物转化,对提高富铬酵母的生物疚极     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Summary of development of the theory of stability of colloids and thin films

In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.     

Study of hydration of two cements of different strengths

Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M_o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700^oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

Thermodynamics of the formation of oxosulfides of rare-earth elements

The enthalpies of solution of several oxosulfides of rare-earth elements and the high-temperature enthalpies of oxosulfides and oxosulfates of lanthanum and yttrium were measured using solution calorimetry and high-temperature microcalorimetry techniques. Standard enthalpies of formation and some thermodynamic properties of oxosulfides and oxosulfates were calculated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2 pp. 294–297, February, 1997.     

探究“铁的锈蚀条件”实验创新设计

设计了铁的锈蚀实验,说明了铁钉的处理方法,增加了温度、酸、碱的影响条件,实现了铁跟蒸馏水及空气中氧气快速反应而生锈,使实验在5 min左右就能够得到准确的结果。