The phospholipids of corynebacteria

The phospholipids ofCorynebacterium diphtheriae, Corynebacterium xerosis, Corynebacterium equi andCorynebacterium ovis were examined, largely by chromatographic procedures. In all of these, lipids of the phosphoinositide and mannophosphoinositide type were prominent. In contrast to the mycobacteria, the mannophosphoinositides of the corynebacteria were all dimannophosphoinositides; however, as in mycobacteria, these dimannophosphoinositides apparently occurred in the diacylated and triacylated forms—the tetraacylated component prominent in mycobacteria was absent. Phosphatidylethanolamine and phosphatidylserine were also absent. InCorynebacterium diphtheriae the major single phospholipid corresponded to phosphatidylglycerol: cardiolipin also appeared to be a major lipid. The fatty acids of the corynebacterial phospholipids were distinguished by the presence of branched chain isomers of medium chain length. The importance of phospholipids in the taxonomy of the actinomycetes and related eubacteria is discussed.     

An equivalent circuit method for sulphur electrode modelling

A method is presented for calculating the reaction-rate distributions and resistances of sulphur electrodes by means of an equivalent circuit treatment. This method can be used to model both flat-plate and tubular cells (of either central sodium or central sulphur configuration). The effects of pole activity and pole—matrix contact resistance can be included in the treatment, which can also be used to model electrodes containing more than one variety of carbon matrix.     

The Effect of a Brief Salivary α-Amylase Exposure During Chewing on Subsequent in Vitro Starch Digestion Curve Profiles

There is inconsistency between current in vitro digestion methods with regard to accommodation of a (salivary) α-amylase exposure during the oral phase. The effect of a salivary α-amylase pre-exposure on subsequent in vitro starch digestion curve profiles for various foods was investigated. Foods were chewed, expectorated and the boluses left to rest for 0-15 min. During pancreatic digestion, aliquots were taken and hydrolysis curves constructed for comparison against those of the same foods comminuted with a manually-operated chopper, hence spared exposure to saliva. Hydrolysate aliquots taken at T(0) (time zero) of the digestion of chewed samples contained higher levels of glucose and dextrins compared with chopped samples. Pancreatin activity immediately overwhelmed differences in sugar released due to salivary amylase activity. Within 10 min no differences were detectable between hydrolysis curves for chewed and chopped foods. Salivary amylase pretreatment does not contribute to the robustness or relative accuracy of in vitro methods.     

Parallel implementation of isothermal and isoenergetic Dissipative Particle Dynamics using Shardlow-like splitting algorithms

A parallel implementation of the Shardlow splitting algorithm (SSA) for Dissipative Particle Dynamics (DPD) simulations is presented. The isothermal and isoenergetic SSA implementations are compared to the DPD version of the velocity-Verlet integrator in terms of numerical stability and performance. The integrator stability is assessed by monitoring temperature, pressure and total energy for both the standard and ideal DPD fluid models. The SSA requires special consideration due to its recursive nature resulting in more inter-processor communication as compared to traditional DPD integrators. Nevertheless, this work demonstrates that the SSA exhibits stability over longer time steps that justify its regular use in parallel, multi-core applications. For the computer architecture used in this study, a factor of 10–100 speedup is achieved in the overall time-to-solution for isoenergetic DPD simulations and a 15–34 speedup is achieved for the isothermal DPD simulations.     

Interfacial Microstructure and Chemistry of SiC/BN Dual-Coated Nicalon-Fiber-Reinforced Glass-Ceramic Matrix Composites

Glass-ceramic composites with improved high-temperature mechanical properties have been produced by incorporating continuous SiC fibers into a barium magnesium aluminosilicate matrix. Control of the fiber/matrix interface was achieved by a dual-layer coating of SiC/BN(C) applied to the fibers by CVD. The weakly bonded interface resulted in composites with high fracture toughness and strength up to 1100°C, and the composite system was oxidatively stable during long-term exposure to air at high temperatures. Composites with different thermal and mechanical histories were studied, and interfaces were characterized using transmission electron microscopy (TEM), Auger electron spectroscopy, and fiber pushout tests. Observations of interfacial microstructure were correlated with the mechanical properties of the composite and with interface properties determined from fiber push-out tests.     

The effect of zinc fertilizer on take-all and the grain yield of wheat grown on zinc-deficient soils of the Esperance region,Western Australia

Wheat plants were grown in field experiments with five levels of zinc (Zn) fertilizer applied to plots in 1983. The plots were continuously cropped with wheat to allow the build up ofGaeumannomyces graminis var.tritici (Ggt). For experiments 1 and 2, there were high levels of Ggt in the second and third years while for experiment 3 there were high levels of Ggt incidence in the third and fourth year of continuous cropping. The Zn status of the wheat plants, grain yield, and the incidence and severity of take-all were measured for every experiment each year.The Zn-deficient wheat plants were more severely infected by Ggt. However, increasing the Zn supply beyond that required for maximum grain yield had no further effects on decreasing the severity of take-all. The Zn concentration in the youngest emerged blade (YEB) suggested that the Zn status of the wheat plant ranged from severely Zn-deficient through marginal deficiency to sufficiency.The Zn-deficient wheat plant was more susceptible to Ggt infection than Zn-adequate plants. The severity of take-all in the final year was still high in Zn-adequate plants, suggesting high levels of applied Zn (11.2 kg Zn/ha in 1983) had no fungistatic effect on Ggt.     

Development of combinatorial chemistry methods for coatings: high-throughput optimization of curing parameters of coatings libraries

An automated analytical system has been implemented for the high-throughput optimization of processing conditions such as curing parameters in fabrication of UV-cured automotive organic protective coatings. Selection of optimum process conditions of combinatorial arrays of coatings is essential to correlate the high-throughput screening and conventional processes and to achieve the desired physical properties of coatings. For monitoring of curing conditions of each coating in the array, a viscosity-sensitive fluorophore 4,4'-bis(2-benzoxazolyl)stilbene was incorporated into coating formulations. This fluorescence tagging approach permitted us to combine a gradient temperature heater and a UV curing system with the full capabilities of our high-throughput screening system, including generation of spectroscopic data and its analysis. This investigation demonstrated the possibility of rapid decoupling of temperature and radiation effects in curing of UV-curable coating formulations by using multiple coatings and process conditions at once. While the system described here was implemented for high-throughput optimization of temperature conditions of radiation curing of arrays of organic protective coatings for automotive applications, this system can be further applied for a variety of other applications where optimization of process parameters can be studied in situ or off-line using optical spectroscopic tools.