The QCHB model of fluids and their mixtures

The essentials of the QCHB (quasi-chemical hydrogen-bonding) equation-of-state model are presented along with some applications for calculations of phase equilibria and interfacial properties of fluids and their mixtures. This is a model applicable to non-polar systems as well as to highly non-ideal systems with strong specific interactions, to systems of small molecules as well as to macromolecules, including polydisperse polymers, glasses, and gels, to liquids as well as to vapours including supercritical systems, to homogeneous as well as to inhomogeneous systems. A quasi-thermodynamic approach of inhomogeneous systems is used for modeling the fluid–fluid interface. Consistent expressions for the interfacial tension and interfacial profiles for various properties are presented. A satisfactory agreement is obtained between experimental and calculated surface tensions. Extension of the approach to mixtures is examined along with the associated problems for the numerical calculations of the interfacial profiles. A new equation is derived for the chemical potentials in the interfacial region, which facilitates very much the calculation of the composition profiles across the interface. The relation of the model with the COSMO-RS approach is also discussed.     

Interactions and uses of antisense peptides in affinity technology.

Antisense peptides, amino acid sequences encoded in the antisense strand of DNA, can interact with significant affinity and selectivity with their corresponding sensepeptides. Experimentally, sense-antisense peptide recognition has been observed repeatedly. However, skepticism about the biological relevance of this phenomenon has persisted. This is due in part to the unexpected and somewhat couterintutive nature of the interaction as well as to its non-universality as an empirical observation. Nonetheless, antisense peptides in several cases investigated so far have been used as immobilized ligands for the successful affinity chromatographic separation of native (sense) peptides and proteins. For example, immobilized antisense peptides corresponding to Arg8-vasopressin (AVP) have been used to separate vasopressin from oxytocin chromatographically as well as to affinity capture AVP-receptor complex. These results, together with improved understanding of the general features of amino acid sequence which drive antisense-sense peptide interactions as well as new ideas for making antisense peptides chimeras, are beginning to suggest improved ways to make antisense-related peptides as affinity agents for separation as well as for other biotechnology applications.     

The trapping of indoor air contaminants

The removal of indoor air contaminants by reactivity with air filters coated with reagents has been found to be effective for aldehydes, acidic and basic vapours as well as isocyanates Coatings of polymeric amines were used for formaldehyde trapping as well as for the removal of acidic vapours and for the removal of isocyanates. The addition of glycerol as a plasticizer for the coating can also be an effective reagent.     

Quality of sugarcane in productive process of ethanol evaluated by INAA

Soil as an impurity in sugarcane is a serious problem for the ethanol industry, increasing production and maintenance costs and reducing the productivity. Fe, Hf, Sc and Th determined by INAA were used as tracers to assess the amount of soil in sugarcane from truckloads as well as in the juice extraction process. Quality control tools were applied to results identifying the need for stratification according to soil type and moisture. Soil levels of truckloads had high variability indicating potential for improving cut and loading operations. Samples from the juice extraction process allowed tracking the soil in the mill tandem.     

Synthesis of 1-aryl-1H-indazoles via palladium-catalyzed intramolecular amination of aryl halides

Palladium-catalyzed cyclization of arylhydrazones of 2-bromoaldehydes and 2-bromoacetophenones to give 1-aryl-1H-indazoles has been studied in detail. The cyclization of arylhydrazone of 2-bromobenzaldehydes can be performed with good to high yields using Pd(dba)2 and chelating phosphines, of which the most effective are rac-BINAP, DPEphos, and dppf, in the presence of Cs2CO3 or K3PO4 as a base. Electron-rich, bulky ligands commonly employed for intermolecular amination such as PtBu3 and o-PhC6H4PtBu2 were shown to be ineffective for cyclization and to lead instead to extensive oligomerization and tarring. The method developed is applicable for preparation of a wide scope of indazoles bearing electron-donating or electron-withdrawing substituents, among them, unprotected carboxyl, as well as various indazole heteroanalogues. The cyclization of arylhydrazones of less reactive halides such as 2-chlorobenzaldehyde, as well as 2-bromoacetophenone and bromotetralone, has been achieved. The purity of the starting hydrazone has been shown to be a critical parameter, as various impurities inhibit the cyclization.     

Anaerobic Calorimetry of the Growth of Lactobacillus Helveticus Using a Highly Sensitive Bio-RCl

To meet the need for studies of anaerobic microbial and animal cell cultures involving much lower heat effects as compared to aerobic microbial cultures, a bench scale calorimeter, Bio-RCl, has been improved for achieving a higher long-term sensitivity. This newly improved Bio-RCl was used for heat measurement of anaerobic growth of Lactobacillus helveticus. The results showed that the bench-scale calorimetry has powerful potential for on-line monitoring and control of anaerobic bioprocesses as well as fundamental studies, such as stoichiometry, thermodynamics and kinetics of cellular growth. This revised version was published online in August 2006 with corrections to the Cover Date.     

Elimination of matrix effects for static headspace analysis of ethanol.

The intention of this work was to develop a simple and fast procedure for a determination of small amounts of ethanol in aqueous protein containing solutions based on combined headspace gas chromatography. In order to provide for short analysis time static headspace methodology was considered for this purpose. In this context the influence of the matrix composition onto the analytical results has been established and internal standardization as well as a full evaporation technique have been evaluated as promising alternatives for a compensation of matrix effects. With respect to speed of analysis, simplicity of sample handling as well as the quality of the analytical performance parameters, precision and accuracy, the full evaporation technique proved to be superior. Thus, the static equilibration of a 20 microliters sample aliquot in a conventional headspace sample vial for 5 min at 100 degrees C is sufficient to obtain equilibrium conditions for gas chromatographic analysis. The accuracy of this method was verified by robust regression analysis and exhibited excellent robustness within the required limits of sample composition ranging from 0 to 20% (w/w) protein content and up to 5 g/l salt content.     

A Review of Cellulose and Cellulose Blends for Preparation of Bio-derived and Conventional Membranes,Nanostructured Thin Films,and Composites

Cellulose has been used as a raw material for the manufacture of membranes and fibers for many years. This review gives the background of the most recent methods of treating or dissolving cellulose, and its derivatives to form polymer films or membranes for a variety of applications. Indeed, some potential applications of bacterial cellulose, nanofibrillar cellulose (NFC) for films showing enhanced barrier characteristics are reviewed as well as the utilization of cellulose nanonocrystals (CNC) for production of highly oriented super strong films or thin films is discussed. Because of the success of the Lyocell process as well as the amine/metal thiocyanate solvent blends of cellulose and other polysaccharides like starch, chitosan, and other natural polymers. Consequently, the use of cellulose (or its derivatives) and another polysaccharide dissolved as a blend is also elaborated. It is our hope that the reader will want to follow up and investigate these new systems and use them to develop end use materials for all sorts of applications, from medical to water filtration, or electrogels for use in batteries.     

Application of carbon nanotubes as solid-phase extraction sorbent for analysis of chlorophenols in water samples

The aim of this work was to investigate the efficiency of various MWCNTs as SPE materials for the preconcentration of chlorophenols. The COOH-functionalized MWCNTs and MWCNTs were used as SPE sorbents. To evaluate the capability of MWCNTs for the preconcentration of chlorophenols from water samples, 2,4-chlorophenol, 4-chlorophenol, 2,4,6-chlorophenol, 2,6-chlorophenol, 3,4-chlorophenol, and 2-chlorophenol were used as model compounds. Chlorophenols were extracted with acetone, methanol, ethanol, and dichloromethane, and determined by gas chromatography–mass spectrometry. COOH-functionalized MWCNTs <8 nm were found to be the best sorbent for the tested chlorophenols. For COOH-functionalized MWCNTs <8 nm, the recovery rates for all chlorophenols were higher than 50% when acetone or ethanol was used as eluents. In the case of dichloromethane elution, recovery rates for chlorophenols were from 62.0% for 2,6-DCP to 116.8% for 2,4-DCP; only for 2,4,6-TCP was the recovery rate 30.6%. Similar percentage recoveries were achieved with methanol as the eluent.     

The isoprenoid-precursor dependence of Plasmodium spp

Due to the increase in resistance of Plasmodium spp. against available antimalarials, there is a need for new, effective and innovative drugs. The non-mevalonate pathway for the biosynthesis of the universal isoprenoid precursors, which is absent in humans, is suggested as an attractive source of targets for such drugs with a novel mode of action. The biological importance of this pathway to Plasmodium spp. is proven by the efficacy of the clinical candidate fosmidomycin, which inhibits the biosynthesis of isoprenoid precursors; it is, however, less clear which isoprenoid end products are essential for parasite survival. In this Highlight, we identify protein prenylation, isoprene-containing quinone production, N-linked glycosylation as well as carotenoid and vitamin-E biosynthesis as probably essential isoprenoid-dependent physiological processes in Plasmodium. Inhibition of any of these processes blocks parasite development. Furthermore, both protein prenylation of SNARE proteins and a protein tyrosine phosphatase as well as tRNA prenylation have been identified as isoprene-dependent processes for which the physiological role in Plasmodium remains unclear. Therefore, the biosynthetic route to the isoprenoid precursors presents attractive drug targets for the development of antimalarials with novel modes of action.     

Peculiarities of the Porous Structure of Aluminosilicate Mesoporous Substances Obtained in The Presence of Biotemplates

Supramolecular structures of lecithin occurred to be the template in the synthesis of mesoporous aluminosilicates; using of various combinations of lecithin and cetyltrimethyl-ammonium bromide or octadecylamine as templating agents allowed to obtain mesoporous substances with pores up to 100 Å, as well as biporous materials in aluminosilicate system. In the presence of glucose oxidase and cetyltrimethyl-ammonium bromide combinations aluminosilicate substances with complex porous structure were shown to be formed (pore size distributions exhibited 3 peaks, corresponding 3 effective size of mesopores in the 30–100 Å range). The investigation of sorption of glucose oxidase on obtained aluminosilicate mesoporous substances was carried out, the results obtained allowus to consider such materials as prospect for creation high capable and selective sorbents for biomolecules sorption, as well as active elements of chemical and biosensors.     

An Application of Capillary Electrophoresis for the Analysis of Algal Toxins from the Aquatic Environment

In this work capillary electrophoresis (CE) with UV detection has been applied to the analysis of different natural toxins produced in the aquatic environment. This technique is presented as an alternative to other chemical techniques such as HPLC, and the optimisation of analytical methodologies was carried out for diverse marine toxins including Paralytic and Amnesic and some polyether toxins, such as Yessotoxins, as well as for certain microcystin toxins produced by cyanobacteria present in freshwaters. Sample preparation steps were optimised and adequate electrophoretic conditions developed for achieving a complete separation of compounds with similar structures involved in such contamination. The influence of the biological matrices where they are involved has also been studied and the potential use of CE-UV as a tool for monitoring these aquatic toxins is also discussed.     

Synthesis of Crystalline Chalcogenides in Ionic Liquids

Crystalline chalcogenides belong to the most promising class of materials. In addition to dense solid‐state structures, they may form molecular cluster arrangements and networks with high porosity, as in the so‐called “zeotype” chalcogenidometalates. The high structural diversity comes along with interesting physical properties such as semi‐/photoconductivity, ion transport capability, molecular trapping potential, as well as chemical and catalytic activity. The great interest in the development of new and tailored chalcogenides has provoked a continuous search for new and better synthesis strategies over the years. The trend has clearly been towards lower temperatures for both economic and ecological reasons as well as for better reaction control. This led to the application of ionic liquids as a designer‐like medium for materials synthesis. In this Review, we summarize recent developments and present a survey of different chalcogenide families along with their properties.     

Exploratory analysis of simultaneous degradation of anthocyanins in the calyces of flowers of the Hibiscus sabdariffa species by PARAFAC model.

A three-way resolution method based on PARAFAC model was applied for the UV-Vis spectra to study the simultaneous degradation of anthocyanins extracted from fresh calyces of flowers of the Hibiscus sabdariffa. This methodology was used to resolve a chemical system, for which there was no a priori information about the composition or the pure spectra, a so-called black system. In the pH range from 1 to 13, seven species were identified: flavylium cation, carbinol, quinoidal base, E- and Z-chalcones and E- and Z-ionized chalcones. The concentration changes were determined as functions of pH at different wavelengths. The pK values for the acidity constants as well as tautomeric constant were estimated as 2.70, 3.54 and 0.14, respectively. The spectral profiles recovered by the chemometric methods are in excellent agreement with bands of experimental spectra reported in the literature for the species measured at specific pH values.     

Development of caprine liver quality control materials for trace element analysis of biological tissues

Certified reference materials (CRMs) are used in analytical chemistry for method validation studies in order to establish measurement accuracy, traceability, and long-term stability throughout repeated analyses. Quality control (QC) during routine analysis requires access to stable materials appropriate for the sample matrix being analyzed. However, it may be difficult to find representative, low-cost QC materials, especially for specific analytes in biological tissue matrices. Here, four caprine liver pools are prepared for use as internal QC materials for trace element measurements in biological tissue. Analytes of interest include essential and nonessential trace elements and the lanthanide series elements. The suitability of caprine liver to serve as a secondary reference material (RM), as well as for routine QC purposes, is demonstrated through homogeneity and stability measurements, and the acquisition of precision and uncertainty data. Traceability is established for selected analytes for which available CRMs can provide an unbroken chain of calibrations.     

Calculation of vapour-liquid equilibrium of associated systems by an equation of state

A recently proposed equation of state of the van der Waals type is applied to calculate phase equilibria in hydrogen-bonding, non-electrolytic systems. Association is accounted for by treating alcohols, acids, etc., as mixtures of associated species formed by up to 14 monomers. The method involves essentially one weakly temperature-dependent adjustable parameter per binary system.The calculations cover vapour-liquid equilibrium both at low and elevated pressure in binary systems formed by an associating substance and a non-associating compound such as a hydrocarbon or halogenated hydrocarbon. An attempt has been made to include all experimental data available for these systems in the literature. A number of calculations for ternary systems as well as of liquid-liquid equilibria are included, and a limited number of solvated systems are also treated.Owing to its single adjustable parameter, the method may be used to test existing experimental data and to predict such data.     

On the definition of the excess permittivity of a fluid mixture

It is shown that under the assumption of no intermolecular interaction, the permittivity of a homogeneous linear and isotropic fluid mixture is the sum of the individual permittivities weighted with the mole fractions of the components. For definiteness, a proof is given for gasses under standard temperature and pressure; it is, however, easy to generalize it to other conditions, as well as to liquids, as long as the assumption of no intermolecular interaction is retained. Also, although the proof is given for a binary mixture, it is a simple exercise to extend it to any multicomponent mixture.     

Analysis of musk fragrances in environmental samples

The methods for the determination of polycyclic and nitro-aromatic musk compounds in comparison to other fragrances such as OTNE ([1,2,3,4,5,6,7,8-octahydro-2,3,8,8-tetramethylnaphthalen-2yl] ethan-1-one) as well as those for the respective metabolites are described in this contribution. It covers instrumental aspects, as well as procedures for extraction and clean-up. Protocols for the determination of musks in water, sludge, biota, and air are summarised and discussed. Extractions by means of solid phase extraction (SPE) and liquid-liquid extraction (LLE) in case of water samples are evaluated for the diverse applications, i.e., wastewater, surface water and seawater. While LLE is preferred for the analysis of bulk for transport studies and for special process studies SPE might be worth the effort. Considering sludge, sediment and biota samples, drying and successive accelerated solvent extraction. Soxhlet extractions as well as cold column extractions are being compared. ASE has proven to be the most exhaustive and quickest to adopt method. Clean-up by means of size exclusion chromatography and silica sorption chromatography with their respective merits and problems are demonstrated. Suggestions for routine and research analysis are also given. The diverse approaches for enantioselective separations are discussed in respect to HHCB, AHTN and the metabolite HHCB-lactone. The power of two-dimensional (GCxGC) approaches is demonstrated considering the various production impurities (isomers) of the two polycyclic musks with the highest usage rates. The usage of tandem mass spectrometry and high resolution mass spectrometry for the same purpose is also discussed. The identification of an isomer of the HHCB-transformation product HHCB-lactone from wastewater treatment that has not been described in the literature before, is presented as well. Additionally some ideas to make the REACh process more efficient are discussed considering the special experiences from the development of the analysis of musk fragrances in the environment.     

光诱导钌配合物的几何异构和结构异构反应研究进展

金属钌(Ru)的配合物具有丰富的基态和激发态的光物理、光化学性质,在太阳能转换、光催化以及分子识别等方面都得到了广泛深入的研究.光诱导的钌配合物的异构反应是其颇具特色的一类光反应,研究光异构反应对于光能量转化、信息储存以及"分子光开关"和"分子马达"的设计具有重要的意义.本文小结和综述了钌配合物的光诱导几何异构和结构异构反应的特性和机理以及最新的研究进展.