Effect of the Linking Group on the Thermoelectric Properties of Poly(Schiff Base)s and Their Metallopolymers

As polymer-based thermoelectric (TE) materials possess attractive features such as light weight, flexibility, low toxicity and ease of processibility, an increasing number of conducting polymers and their composites with high TE performances have been developed in recent years. Up to date, however, the research focusing on the structure-performance relationship remains rare. In this paper, two series of poly(Schiff base)s with either C=C or C≡C linker and their metallopolymers were synthesized and doped with single-walled carbon nanotubes to evaluate how the linking groups affected the TE properties of the resulting composites. Apart from the effect exerted by the morphology, experimental results suggested that the linkers played a key role in determining the band gaps, preferred molecular conformation and extent of conjugation of the polymers, which became key factors that influenced the TE properties of the resulting materials. Additionally, upon coordination with transition metal ions, the TE properties could be tuned readily.     

Polymer Composites for Thermoelectric Applications

This review covers recently reported polymer composites that show a thermoelectric (TE) effect and thus have potential application as thermoelectric generators and Peltier coolers. The growing need for CO₂‐minimizing energy sources and thermal management systems makes the development of new TE materials a key challenge for researchers across many fields, particularly in light of the scarcity or toxicity of traditional inorganic TE materials based on Te and Pb. Recent reports of composites with inorganic and organic additives in conjugated and insulating polymer matrices are covered, as well as the techniques needed to fully characterize their TE properties.     

气相SiO2在不同pH值介质中的分散特性

以激光动态光散射法考察了气相SiO2在不同pH值的H2SO4和NaOH介质中的分散平均水化粒径与表面Zeta电位及二者间的关系。 Zeta电位数据表明，气相SiO2在水中分散的表面硅羟基的等电点(IEP)和滴定终点(TE)的pH值分别为pH(IEP)=2.09和pH(TE)=7.47，利用滴定终点pH (TE)给出了一种简单的气相SiO2表面Si-OH浓度的测定方法。 分散相粒径数据显示，在等电点和滴定终点之间，气相SiO2在水中的分散粒子的粒径能够稳定在230 nm附近；在H2SO4介质中，当pH＜pH(IEP)时，随着H2SO4浓度的增大，体系中的分散粒子发生聚结而使表观粒径增大；在NaOH介质中，当pH＞pH(TE)时，随着NaOH浓度的增大，分散相的表观水化粒径降低，表明NaOH的加入有利于气相SiO2的分散。     

微量元素与脱发130例临床分析

分析了１３０例脱发病人头发中的微量元素含量，结果证明，虽其临床分型、病理机制有所差异，但均与体内微量元素异常关系密切，并与锌、铁的缺乏关系最明显。以采用微量元素制剂为主，对重症者或兼杂证明显者配以其他疗法，时间缩短，疗效提高。临床有效率达９２．１％，显效率在８０％左右。     

中药中微量元素的存在状态与生物活性关系的研究

本题实质上是中药有效化学成分(ECC)的研究．得出了下列一些研究结果，1．提出了中药TE和中药ECC的研究思路即以中药中TE的存在状态为核心，以中药中TE和有机成分(OC)的相互作用为基础来开展中药TE和中药ECC的研究工作．2．根据中医药理论，运用系统论的原则和方法论以及贝塔朗菲定律．以大量实验结果为基础．提出了“中药有效化学成分的配位化学学说”。其核心是:(1)中药中的有效化学成分可以是OC，也可能是TE;(2)中药中的ECC更有可能是二者的配合反应所形成的配合物．3.在中药中OC和TE的相互配合反应中．即改变了TE的存在在状态后．发现了生物活性和药理作用变化的规律性:(1)有的配合物具有原来二种成分的生物活性;(2)有的配合物则可提高某一成分的生物活性或降低其毒副作用;(3)有的配合物测产生二者所不具备的新的生物活性;(4)TE的生物利用度均有所提高．4．从实验中发现了一些有较好生物活性和药理作用的配合物．为新型配合物中药新药的研制提出了一个新思路．新方向．新方法．5．采用了配位化学的理论和研究方法，把pH电位法和计算机平衡模拟技术相结合，为中药ECC和中药TE的研究工作提供了新的方法．     

Evaluation and Comparison of a 3,5‐Dimethylphenyl Isocyanate Teicoplanin with Phenyl Isocyanate Teicoplanin Chiral Stationary Phase Using RP‐HPLC

HPLC enantiomeric separations of 8 α‐amino acids were achieved using two self‐made chiral stationary phases (CSP)–phenyl isocyanate teicoplanin (Phe‐TE) and 3,5‐dimethylphenyl isocyanate teicoplanin (DMP‐TE), using reversed phase mobile phases. The Phe‐TE or the DMP‐TE CSP was prepared from the TE using derivative agents, phenyl isocyanate or 3,5‐dimethylphenyl isocyanate, respectively. The chromatographic results were given as the retention, selectivity, resolution factor and the enantioselective free energy difference corresponding to the separation of the two enantiomers. The effect of pH, organic modifier type and amount were discussed, and the stereoselectivities for two TE‐based CSPs were compared. The chiral selectivity factor for six α‐amino acids on DMP‐TE is somewhat bigger than that on Phe‐TE CSP under reversed phase (RP) mode. Comparison of the enantiomeric separations using self‐made Phe‐TE and DMP‐TE was conducted to gain a better understanding of the chiral recognition mechanism of the macrocyclic glycopeptide CSP.     

Recent Advances and Perspectives in Analytical Methodologies for Monitoring the Bioavailability of Trace Metals in Environmental Solid Substrates

In the last decades, researchers have realised that the impact of trace elements (TE) in environmental solid substrates on ecological systems and biota cannot be ascertained appropriately by means of total metal content measurements. Assessment of TE chemical forms, types of binding and reactivity of their associations with particulate forms has, thus, been commonly performed via batch-wise equilibrium-based sequential extraction fractionation methods able to discern TE bound to different soil-phase compartments. In this paper, novel analytical strategies for monitoring the mobility, bioavailability and the eventual impact of anthropogenic TE in environmental solids are addressed. The potential of passive dosimeters based on microdialysis sampling for on-site, real-time monitoring of chemical contaminants in pore soil solution is thoroughly discussed and critically compared with active microsamplers. Recent miniaturised configurations designed for following the fate of target pollutants and the on-going chemical changes occurring at local soil sites, e.g., the rhizosphere environment, at high temporal resolution are also presented in detail. Kinetic information on the lability of the various TE forms associated to soil phases under simulated environmental changing conditions – that yield improved knowledge on short-term hazards of TE for the environment – can be obtained in a fully automated mode by means of flow-through microcolumn fractionation procedures. The use of sequential injection analysis, in terms of the implementation of on-line dynamic fractionation, is described and illustrated via selected examples comprising the well-accepted three-step SM&T sequential fractionation, protocol.     

Conducting polymers: Efficient thermoelectric materials

This review highlights the recent progress made in the area of thermoelectric (TE) applications of conducting polymers and related composites. Several examples of such materials and their TE properties are discussed. TE properties of new poly(2,7‐carbazole) derivatives are highlighted. References are also made to carbon nanotube/polymer composites and their improved electrical and TE performance. Studies on polymer/inorganic materials composites have also taken a step forward and have shown very promising TE properties. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

3，5-二甲基苯基异氰酸酯替考拉宁和苯基异氰酸酯替考拉宁手性固定相的评价与比较

用大环抗生素替考拉宁手性固定相(TE CSP)分别与3,5-二甲基苯基异氰酸酯和苯基异氰酸酯反应得到了两种新型的高效液相色谱手性固定相----3,5-二甲基苯基异氰酸酯替考拉宁手性固定相(DMP-TE CSP)和苯基异氰酸酯替考拉宁手性固定相(Ph-TE CSP)。用十八个手性化合物在反相及极性流动相模式对这两种CSP的对映体分离能力进行了评价和比较。在反相流动相中,十二个化合物（包括八个氨基酸和四个非氨基酸化合物----对羟基苯甘氨酸,拉米夫定,醇酸和去甲羟安定）的对映体在这两种手性固定相上都获得了分离,大部分的溶质在DMP-TE上获得了更强的保留和稍好的手性分离效果。在极性流动相中,六个氨基醇类化合物在DMP-TE上获得了更强的保留,但它们在两种CSP上的选择因子几乎没有区别。对自制的替考拉宁衍生物手性固定相进行评价和比较,将有助于大环糖肽类抗生素手性固定相手性识别机理的研究。     

Gaussian-type function set without prolapse 1H through 83Bi for the Dirac-Fock-Roothaan equation

We have developed prolapse free Gaussian basis sets which can be used for 1H to 83Bi, imposing the condition that the Dirac-Fock-Roothaan (DFR) total energy (TE) decreases monotonically toward the numerical DF (NDF) TE as the expansion term increases. An even-tempered basis set was assumed. The resulting sets gave |TE(DFR) - TE(NDF)| < or = 1 x 10(-6) hartree for any atoms less or equal to 83Bi; TE(NDF) = -21 565.638 345, and TE(DFR) = -21,565.638 345 +/- 0.000 001 hartree for Bi when the expansion terms are in the range (58, 58, 58, 36, 36, 36, and 36) and (72, 72, 72, 36, 36, 36, and 36) for (s+, p-, p+, d-, d+, f-, and f+) symmetries, respectively. A practical set with 44, 44, 44, 36, 36, 32, and 32 for the respective symmetries is also proposed where |TE(DFR) - TE(NDF)| < or = 4 x 10(-5).     

Mechanism and specificity of the terminal thioesterase domain from the erythromycin polyketide synthase

BACKGROUND: Polyketides are important compounds with antibiotic and anticancer activities. Several modular polyketide synthases (PKSs) contain a terminal thioesterase (TE) domain probably responsible for the release and concomitant cyclization of the fully processed polyketide chain. Because the TE domain influences qualitative aspects of product formation by engineered PKSs, its mechanism and specificity are of considerable interest. RESULTS: The TE domain of the 6-deoxyerythronolide B synthase was overexpressed in Escherichia coli. When tested against a set of N-acetyl cysteamine thioesters the TE domain did not act as a cyclase, but showed significant hydrolytic specificity towards substrates that mimic important features of its natural substrate. Also the overall rate of polyketide chain release was strongly enhanced by a covalent connection between the TE domain and the terminal PKS module (by as much as 100-fold compared with separate TE and PKS 'domains'). CONCLUSIONS: The inability of the TE domain alone to catalyze cyclization suggests that macrocycle formation results from the combined action of the TE domain and a PKS module. The chain-length and stereochemical preferences of the TE domain might be relevant in the design and engineered biosynthesis of certain novel polyketides. Our results also suggest that the TE domain might loop back to catalyze the release of polyketide chains from both terminal and pre-terminal modules, which may explain the ability of certain naturally occurring PKSs, such as the picromycin synthase, to generate both 12-membered and 14-membered macrolide antibiotics.     

糖尿病人微量元素谱的多元分析

胜多元分析了糖尿病患者样品中微量元素，了解微量元素与糖尿病的关系，并提出了新见解。用ＩＣＰ－ＡＥＳ测定糖尿病患者血、发中１８种微量和宏量元素 ；结果经多元分析处理，找到血、发共有的相关链：Ｍｎ－Ｎｉ－Ｃｕ－ＳｒＴｉ，它与患者年龄、性别、样品无关，看来它提供了机体的特殊信息。     

Research in environmental pollution: XI. A simple and fast method for the estimation of the total TE's of PCDD/F's in sewage sludge samples

A quick and simple method is presented for the estimation of the total TCDD-equivalents (TE) of seventeen PCDD/F congeners in sewage sludge samples on the basis of the TE of the analysed HpCDD and OCDD congeners only. These estimated TE values agreed well with the TE obtained by the analysis of all the seventeen PCDD/F congeners.     

Vanadium-doped BaTiO3 as high performance thermoelectric material: role of electronic structure engineering

It is well known that thermoelectric (TE) materials are the most sought-after ones to mitigate energy crisis. Development of an efficient non-toxic, economic, abundant, and stable TE material is quite difficult due to its complicated traits. BaTiO₃, a perovskite material shows a tremendous potential as a TE material due to its highly tunable electronic structure. Herein, for the first time we report use of dopant to improve the Seebeck coefficient of BaTiO₃. We used first-principles density functional theory calculations to study the effect of vanadium doping in BaTiO_3, and for the first time, we report that V acts as a resonant dopant in BaTiO₃. The study on effect of site occupancy reveals that V in Ba site distorts the density of states below the conduction band by introducing resonance level at the Fermi level. The transport property calculations based on Boltzmann's relation predicts V-doped BaTiO₃ to be a potential TE material. The results also provide new insights into development of BaTiO₃ as a multifunctional material.     

Chemoenzymatic synthesis of the polyketide macrolactone 10-deoxymethynolide

The polyketide synthase-derived pikromycin thioesterase (Pik TE) is unique in its ability to catalyze the cyclization of 12- and 14-membered macrolactones. In this investigation, the total synthesis of the natural hexaketide chain elongation intermediate as its N-acetyl cysteamine (NAC) thioester has been achieved, and its reaction with Pik TE demonstrated the ability of Pik TE to catalyze its macrolactonization to the natural product 10-deoxymethynolide. A steady-state kinetic analysis of the hexaketide chain intermediate with Pik TE was done. A preliminary substrate specificity study with unnatural hexaketide analogues was accomplished, demonstrating the importance of total synthesis in obtaining access to advanced polyketide intermediates. The results show the sensitivity of Pik TE to minor substrate modifications, and illustrate the potential use of thioesterases as versatile macrolactonization catalysts.     

Tuning Optimum Temperature Range of Bi2Te3‐Based Thermoelectric Materials by Defect Engineering

Bi₂Te₃‐based solid solutions, which have been widely used as thermoelectric (TE) materials for the room temperature TE refrigeration, are also the potential candidates for the power generators with medium and low‐temperature heat sources. Therefore, depending on the applications, Bi₂Te₃‐based materials are expected to exhibit excellent TE properties in different temperature ranges. Manipulating the point defects in Bi₂Te₃‐based materials is an effective and important method to realize this purpose. In this review, we focus on how to optimize the TE properties of Bi₂Te₃‐based TE materials in different temperature ranges by defect engineering. Our calculation results of two‐band model revel that tuning the carrier concentration and band gap, which is easily realized by defects engineering, can obtain better TE properties at different temperatures. Then, the typical paradigms about optimizing the TE properties at different temperatures for n‐type and p‐type Bi₂Te₃‐based ZM ingots and polycrystals are discussed in the perspective of defects engineering. This review can provide the guidance to improve the TE properties of Bi₂Te₃‐based materials at different temperatures by defects engineering.     

Comparative Enantioseparation of Seven Amino Alcohols on Teicoplanin‐Based Chiral Stationary Phases

Abstract

The macrocyclic antibiotics represent a relatively new class of chiral selectors in separation science and teicoplanin‐based chiral stationary phases (CSP) have been used successfully in a number of applications in high‐performance liquid chromatography. In the present studies, we self‐prepared two bonded CSPs–teicoplanin (TE) and teicoplanin phenyl isocyanate (TE‐Phe). Seven amino alcohols, propranolol, bisoprolol fumarate, atenolol, salbutamol, isoproterenol, metoprolol, and labetalol were enantioseparated on both self‐made CSPs using methanol as mobile phase and acetic acid (HOAc) and triethylamine (TEA) as mobile phase additives. On both CSPs, the different enantioseparation behavior of analytes with different structure was compared. The influence of the concentration of mobile phase additives (HOAc and TEA) on the enantioseparation was investigated. In all conditions, the retention factors (k′) of seven analytes on TE‐Phe CSP were larger than that on TE CSP. However, the separation factors (α) and resolutions (Rs) on TE‐Phe CSP were smaller than that on TE CSP. The results indicated that the derivatized TE‐Phe CSP is not efficient as original teicoplanin CSP. Our observations also suggested that, for teicoplanin‐based CSPs, π‐π interactions and dipole‐dipole between solutes and CSPs mainly contribute to the retention of solutes on CSPs while hydrogen bonding and steric interactions play important roles in the chiral recognition for teicoplanin‐based CSPs.     

Phase and Defect Engineering of GeTe-based Alloys for High Thermoelectric Performance

The widespread applications of thermoelectric(TE) materials in power generation and solid-state cooling require improving their TE figure of merit(ZT) significantly. Recently, GeTe-based alloys have shown great promise as mid-temperature TE materials with superhigh TE performance, mostly due to their relatively high-degeneracy band structures and low lattice thermal conductivity. In this perspective, we review the most recent progress of the GeTe-based TE alloys from the view of phase and defect engineering. These two strategies are the most widely-used and efficient approaches in GeTe-based alloys to optimize the transport properties of electrons and phonons for high ZT. The phase transition from rhombohedral to cubic structure is believed to improve the band convergence of GeTe-based alloys for higher electrical performance. Typical defects in GeTe-based alloys include the point defects from Ge vacancies and substitutional dopants, linear and planar defects from Ge vacancies. The defect engineering of GeTe-based alloys is important not only for optimizing the carrier density but also for tuning the band structure and phonon-scattering processes. The summarized strategies in this review can also be used as a reference for guiding the further development of GeTe-based alloys and also other TE materials.