studies on the $beta$ -turn of peptides. v. turn preference of peptide sequences analyzed by conformational energy calculation on dipeptide models and by cd spectra of chromophoric derivatives

empirical conformational energy calculations were performed on ac-l-pro-d-ala-nhch//3 and ac-d-ala-l-pro-nhch//3. in order to study the turn tendency of the dipeptide sequences turn probabilities and average interterminal distances were calculated. much larger turn preference of d-ala containing sequences was indicated compared with the c..

factors influencing the quality of solder powder used in solder pastes for thick film circuits, printed circuitboards and the electronics industry in general

the purpose of this report is to present an analysis of factors affecting the quality of solder powder used in solder paste systems these systems, used in hybrid microelectronics, are applied to complex thick film cirucits using 'silk' screen techniques common to the industry. the report deals with actual results and recommendations conce..

physical structure of cellulose with the help of the programmed usage of molecular spectroscopy methods

application of the automated mcs (multiparametric complex spectroscopic) method to the investigation of diverse samples of cotton and wood celluloses, which differ in the method of gathering of the cotton (by hand and mechanical), the type of original wood and the method of its cooking, the average degree of polymerization, the molecular ..

matrix synthesis of copolymer chains with a definite alternation of monomer units

the method of copolymerization from two-component vapor mixtures of vinylidene chloride and acrylic acid on polyamide supports have been used to bring about a matrix synthesis of the copolymer chains. the composition of the chains and the alternation of monomer units is determined by the distribution of amide groups in the polyamide chain..

large scale integration (lsi) chip carriers

the development of cermic chip carriers has created a demand for new high density printed wiring board interconnections. the technical challenges of this packaging concept include thermal management, high speed electrical performance and reliability of the interconnect over a wide range of environmental conditions provisions must be made ..

direct mounting of ceramic leadless chip carrier onto glass epoxy circuit board

leadless chip carrier (lcc) packages provide an excellent means of protecting/connecting the complex multileaded circuit functions of lsi, vlsi, and vhsic. however, before the use of lcc in commercial and military equipment can become cost-effective, reliable methods for mounting lcc's to standard, printed circuit boards must be developed..

adsorption of complex aluminum species by cellulosic fibers

using an improved description of the aqueous equilibria of the aluminum ion, a study was undertaken to improve the general understanding of the adsorption of complex aluminum species by cellulosic fibers under conditions of a papermaking system. the adsorption of aluminum for both aluminum chloride and aluminum sulfate was found to be pri..

determination of cyclopropenoic fatty acids by reversed-phase liquid chromatography and gas chromatography

a description is given of analyses in parallel by gas-liquid chromatography and high-performance liquid chromatography (glc-hplc) for quantitative analysis of cyclopropenoic fatty acid (cpefa) methyl esters in oils. the separation of the two cpefa (malvalic and sterculic) methyl esters from methyl oleate was carried out by hplc using a re..

persistence of pesticides in soil leachates: effect of ph, ultra-violet irradiation and temperature

the effects of ph, ultra-violet irradiation and temperature on the persistence and breakdown of dieldrin, endosulphan, gamma-hch and pyrolan were studied in leachates from a loam soil. except for dieldrin which remained exceptionally stable throughout the ph range, persistence of pesticides decreased progressively as ph increased after ex..

surface activity of separated phases of the surfactant/water/corn oil system

aqueous solutions of octyl phenoxy polyethoxy ethanol (triton x-114) show phase separation on standing and also in the presence of corn oil. the surface tension of varying concentrations of the upper phase of these systems decreases markedly at lower concentrations, tending to become constant at higher concentrations. the surface activity..