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Three-component System (three-component + system)
Selected AbstractsCatalyst-Free Microwave-Assisted Synthesis of ,-Aminophosphonates in a Three-Component System: R1C(O)R2,(EtO)2P (O)H,RNH2.CHEMINFORM, Issue 41 2005Maria M. Kabachnik Abstract For Abstract see ChemInform Abstract in Full Text. [source] Plants, gall midges, and fungi: a three-component systemENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2008Odette Rohfritsch Abstract Larvae of gall midges (Diptera: Cecidomyiidae) induce the activation of plant cells, partial cell lysis, and differentiation of nutritive tissue. Specialized nutritive tissue is essential for larval development and plays a key role in gall organization. Midges of the tribes Lasiopterini and Asphondyliini, however, do not induce nutritive tissues as part of the formation of their galls. Instead, these ,ambrosia galls' contain fungal mycelia that line the interior surface of the chambers. The fungi not only provide Lasiopterini with nutrition, they also penetrate the stems, induce the lysis of the middle lamella of host cells, and open a channel to the vascular bundles. Larvae of Lasioptera arundinis (Schiner) (Lasiopterini) follow the fungus and feed on its mycelium along with adjoining stem cells of Phragmites australis (Cav.) Trin. (Poaceae). Eggs together with fungal conidia are deposited by the imago on the host. Asphondyliini use a needle-like ovipositor to introduce fungal conidia and eggs into the organs they attack. Larvae of Schizomyia galiorum Kieffer (Asphondyliini) are unable to initiate the gall or to develop in the flowers of Galium mollugo L. (Rubiaceae) without their fungal associate. In this article, I provide an overview of oviposition behaviour in the Asphondyliini, as well as descriptions of the ovipositor and the female post-abdominal segments. Gall formation by Lasiopterini and Asphondyliini and the role of associated fungi are discussed, as is the role of the fungus as an inquiline or an organizer of gall tissues and a nutritive device. [source] Outcomes of the International Union of Crystallography Commission on Powder Diffraction Round Robin on Quantitative Phase Analysis: samples 1a to 1hJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2001Ian C. Madsen The International Union of Crystallography (IUCr) Commission on Powder Diffraction (CPD) has sponsored a round robin on the determination of quantitative phase abundance from diffraction data. Specifically, the aims of the round robin were (i) to document the methods and strategies commonly employed in quantitative phase analysis (QPA), especially those involving powder diffraction, (ii) to assess levels of accuracy, precision and lower limits of detection, (iii) to identify specific problem areas and develop practical solutions, (iv) to formulate recommended procedures for QPA using diffraction data, and (v) to create a standard set of samples for future reference. Some of the analytical issues which have been addressed include (a) the type of analysis (integrated intensities or full-profile, Rietveld or full-profile, database of observed patterns) and (b) the type of instrument used, including geometry and radiation (X-ray, neutron or synchrotron). While the samples used in the round robin covered a wide range of analytical complexity, this paper reports the results for only the sample 1 mixtures. Sample 1 is a simple three-phase system prepared with eight different compositions covering a wide range of abundance for each phase. The component phases were chosen to minimize sample-related problems, such as the degree of crystallinity, preferred orientation and microabsorption. However, these were still issues that needed to be addressed by the analysts. The results returned indicate a great deal of variation in the ability of the participating laboratories to perform QPA of this simple three-component system. These differences result from such problems as (i) use of unsuitable reference intensity ratios, (ii) errors in whole-pattern refinement software operation and in interpretation of results, (iii) operator errors in the use of the Rietveld method, often arising from a lack of crystallographic understanding, and (iv) application of excessive microabsorption correction. Another major area for concern is the calculation of errors in phase abundance determination, with wide variations in reported values between participants. Few details of methodology used to derive these errors were supplied and many participants provided no measure of error at all. [source] Multivariate Composition Distribution in Free-Radical Multicomponent Polymerization, 1MACROMOLECULAR THEORY AND SIMULATIONS, Issue 7 2003Hidetaka Tobita Abstract Statistical multicomponent polymerization is a typical example of a Markovian process for which the generating function approach can be applied. Up to the present, generating functions have been used mainly to obtain analytical solutions. However, recent advances of computer software capable of handling symbolic calculations can throw new light on the old mathematical technique. After formulating the equations representing the instantaneous composition distribution of polymers for a given chain length, r, the illustrative numerical calculations are conducted by using the symbolic calculator. For a multicomponent polymerization consisting of more than two components, the second component distribution is dependent on the composition of the first component (F1), which is represented by the conditional probability given r and F1, . It is found that is well approximated by the Gaussian distribution with the variance following the relationship, , as in the case of the first component distribution , where A and B are the constants. With the knowledge of chain length distribution, it is now possible to conduct the full analysis of multivariate distribution of chain length and compositions for multicomponent free-radical polymerization. Bivariate distribution of composition F1 and F2 for chain length r,=,100 in a three-component system. [source] A DNA replicon system for rapid high-level production of virus-like particles in plantsBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2009Zhong Huang Abstract Recombinant virus-like particles (VLPs) represent a safe and effective vaccine strategy. We previously described a stable transgenic plant system for inexpensive production and oral delivery of VLP vaccines. However, the relatively low-level antigen accumulation and long-time frame to produce transgenic plants are the two major roadblocks in the practical development of plant-based VLP production. In this article, we describe the optimization of geminivirus-derived DNA replicon vectors for rapid, high-yield plant-based production of VLPs. Co-delivery of bean yellow dwarf virus (BeYDV)-derived vector and Rep/RepA-supplying vector by agroinfiltration of Nicotiana benthamiana leaves resulted in efficient replicon amplification and robust protein production within 5 days. Co-expression of the P19 protein of tomato bush stunt virus, a gene silencing inhibitor, further enhanced VLP accumulation by stabilizing the mRNA. With this system, hepatitis B core antigen (HBc) and Norwalk virus capsid protein (NVCP) were produced at 0.80 and 0.34 mg/g leaf fresh weight, respectively. Sedimentation analysis and electron microscopy of transiently expressed antigens verified the efficient assembly of VLPs. Furthermore, a single replicon vector containing a built-in Rep/RepA cassette without P19 drove protein expression at similar levels as the three-component system. These results demonstrate the advantages of fast and high-level production of VLP-based vaccines using the BeYDV-derived DNA replicon system for transient expression in plants. Biotechnol. Bioeng. 2009;103: 706,714. © 2009 Wiley Periodicals, Inc. [source] Intramembrane-sensing histidine kinases: a new family of cell envelope stress sensors in Firmicutes bacteriaFEMS MICROBIOLOGY LETTERS, Issue 2 2006Thorsten Mascher Abstract Two-component signal-transducing systems (TCS) consist of a histidine kinase (HK) that senses a specific environmental stimulus, and a cognate response regulator (RR) that mediates the cellular response. Most HK are membrane-anchored proteins harboring two domains: An extracytoplasmic input and a cytoplasmic transmitter (or kinase) domain, separated by transmembrane helices that are crucial for the intramolecular information flow. In contrast to the cytoplasmic domain, the input domain is highly variable, reflecting the plethora of different signals sensed. Intramembrane-sensing HK (IM-HK) are characterized by their short input domain, consisting solely of two putative transmembane helices. They lack an extracytoplasmic domain, indicative for a sensing process at or from within the membrane interface. Most proteins sharing this domain architecture are found in Firmicutes bacteria. Two major groups can be differentiated based on sequence similarity and genomic context: (1) BceS-like IM-HK that are functionally and genetically linked to ABC transporters, and (2) LiaS-like IM-HK, as part of three-component systems. Most IM-HK sense cell envelope stress, and identified target genes are often involved in maintaining cell envelope integrity, mediating antibiotic resistance, or detoxification processes. Therefore, IM-HK seem to constitute an important mechanism of cell envelope stress response in low G+C Gram-positive bacteria. [source] Studies on the adaptability of different Borgen norms applied in self-modeling curve resolution (SMCR) methodJOURNAL OF CHEMOMETRICS, Issue 6 2009Róbert Rajkó Abstract Lawton and Sylvestre, and later Borgen et al. provided first the analytical solution for determining feasible regions of self-modeling curve resolution (SMCR) method for two- and three-component systems, respectively. After 20 years, Rajkó and István recently revitalized Borgen's method given a clear interpretation and algorithm how to draw Borgen plots using computer geometry tools; later Rajkó proved the existence of the natural duality in minimal constrained SMCR. In both latter cases, 1-norm was used to normalize raw data; however Borgen et al. introduced a more general class of normalization. In this paper, the definition and detailed descriptions of Borgen norms are given firstly appearing in the chemical literature. Some theoretical and practical studies on the adaptability of some Borgen norms used for SMCR method are also provided. Copyright © 2009 John Wiley & Sons, Ltd. [source] Photopolymerization of 1,6-hexanedioldiacrylate initiated by three-component systems based on N -arylphthalimidesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2004T. Brian Cavitt Abstract Three-component photoinitiators comprised of an N -arylphthalimide, a diarylketone, and a tertiary amine were investigated for their initiation efficiency of acrylate polymerization. The use of an electron-deficient N -arylphthalimide resulted in a greater acrylate polymerization rate than an electron-rich N -arylphthalimide. Triplet energies of each N -arylphthalimide, determined from their phosphorescence spectra, and the respective rate constants for triplet quenching by the N -arylphthalimide derivatives (acquired via laser flash photolysis) indicated that an electron,proton transfer from an intermediate radical species to the N -arylphthalimide (not energy transfer from triplet sensitization) is responsible for generating the initiating radicals under the conditions and species concentrations used for polymerization. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4009,4015, 2004 [source] | ||||||||||||||||