On the notion of control signals in digital designs

The concept of control signals is fundamental to digital design. It evokes the notion of one or more signals that influence computation on other signals in a system, and regulate the behavior of the system. A formal definition of control signals is presented. It is argued that knowledge of the control signals in a complex design such as a microprocessor or a computer is crucial to the comprehension and specification of the design and that knowledge of the control signals of a design leads to a more efficient hardware implementation. The identification of control signals in two microprocessors are presented as examples     

Estimation of sharma constant and thermoacoustic properties of fatty acids

From the volume expansivity α, a number of thermoacoustic parameters, including the Sharma constant,S ₀, are estimated for four fatty acids as a function of temperature. The Sharma constant, which was established to be a constant with the characteristic value 1.11 ± 0.01 over a number of systems investigated by earlier investigators, is also found to be a constant with the same value for all fatty acids under investigation. Further, the Sharma constant,S ₀, is independent of temperature and dependent only on α. All other parameters estimated are discussed and compared with the values reported in the literature by earlier workers for different systems.     

Copper extraction into emulsion liquid membranes using LIX 984N-C®

The extraction of copper from aqueous sulfate media into ELMs using the extractant LIX 984N-C was studied. Appropriately characterized emulsions on the basis of viscosity and internal drop sizes were used to study the effect of different parameters on extraction. The effects of stirring speed, surfactant concentration, pH of the external continuous phase, carrier concentration, internal phase stripping acid concentration and initial copper concentration are reported. These results show that LIX 984N-C efficiently extracts copper at low pH values typical of leach solutions. It was found that LIX 984N-C could extract up to 80% copper from aqueous solutions at pH value of 1. Performance of LIX 984N-C was also compared with LIX 84 and LIX 84-I at different pH values. Results indicate that LIX 984N-C could open up new avenues for extraction of copper into ELMs, not only from dilute solutions, but also from sulfuric acid leach solutions.     

Cooking characteristics,chemical composition and protein quality of newly developed genotypes of pigeonpea (Cajanus cajan L)

Eight newly developed pigeonpea genotypes (ICPL 87, ICPL 151, ICPL 270, ICPL 366, ICPL 87051, ICPL 87063, ICPL 87067, and ICPV 1), and the two controls (BDN 2 and C 11) were analysed for cooking quality parameters and chemical composition, including amino acids and minerals. Protein quality was evaluated by determining the true protein digestibility, biological value, net protein utilisation (NPU), and utilisable protein. These genotypes differed significantly (P < 0–01) in the dhal cooking time. Sensory properties of dhal of these genotypes were found to be within the acceptable range, even though there were considerable differences among genotypes. Dhal protein, calcium, magnesium, zinc, and iron contents of these genotypes showed noticeable differences. Calcium content of ICPL 87067 was the highest (85-6 mg per 100 g) and of ICPL 87 the lowest (54-4 mg per 100 g) indicating large differences among the newly developed genotypes. No noticeable differences in sulphur-containing amino acids of these genotypes were observed. NPU was the highest (65–4%) for ICPL 366 and the lowest (56–6%) for ICPL 270 and ICPL 87067 indicating significant (P < 0–01) differences among genotypes studied.     

Separation of nickel catalyst by microfiltration

Ceramic membranes with pore size of 0.1 and 0.2 µm are used for the separation of nickel catalyst. Effect of trans‐membrane pressure (TMP), linear velocity, temperature and nickel content (solute) on flux and rejection has been investigated. The flux increased with increase in pore size of the membrane. The rejection characteristics were similar for 0.1 and 0.2 µm membranes. The nickel content and iodine value of the membrane‐filtered oil was comparable with that of conventional processes. Permeate flux increased with increase in temperature. Flux increased with increase in linear velocity and a marginal rise was observed above 2.09 m/s. The rejection characteristics were only slightly affected by higher linear velocity. The flux improved after back flushing. The average flux was higher with back flushing as compared to continuous (with out back flushing) filtration process. The results indicated that the secondary layer effect was more pronounced in microfiltration. The flux decreased with increase in solute concentration. The rejection characteristics were not affected by solute concentration. The rejection characteristic of the membranes remained unaltered after membranes were repeatedly cleaned with sodium hydroxide and HCl solutions, however, the flux was decreased marginally.     

Application of natural receptors in sensors and assays

Biosensors are analytical devices that use a biological or biologically derived material immobilized at a physicochemical transducer to measure one or more analytes. Although there are a large number of reviews on biosensors in general, there has been little systematic information presented on the application of natural receptors in sensor technology. This perspective discusses broadly the fundamental properties of natural receptors, which make them an attractive option for use as biorecognition elements in sensor technology. It analyses the current situation by reference to typical examples, such as the application of nicotinic acetylcholine receptor and G protein-linked receptors in affinity sensors and analyses the problems that need to be resolved prior to any commercialization of such devices.     

A Technique for Optimal Sequential Maintenance Scheduling

This paper presents the mathematical development of, and a simple solution technique for, an optimal sequential maintenance scheduling problem. The model is shown to satisfy the Kuhn-Tucker conditions, the necessary and sufficient conditions for the existence of an optimal solution. Real-world systems consisting of mixtures of constant and increasing failure rate devices are considered in the model. Sequential preventive maintenance schedules are developed for groups of identical items with increasing failure rates. Provision is made for the corrective maintenance of these groups if failures occur in between the preventive maintenance schedules. Also, constant failure rate devices are accorded corrective maintenance when failures occur. Optimality is achieved by minimizing the total annual maintenance cost, subject to constraints on the system availability, number of maintenance personnel and intervals of preventive maintenance. The model is applied to a coal mine power system example.     

Structure and function of animal fatty acid synthase

Fatty acid synthase (FAS; EC 2.3.1.85) of animal tissues is a complex multifunctional enzyme consisting of two identical monomers. The FAS monomer (approximately 270 kDa) contains six catalytic activities and from the N-terminus the order is beta-ketoacyl synthase (KS), acetyl/malonyl transacylase (AT/MT), beta-hydroxyacyl dehydratase (DH), enoyl reductase (ER), beta-ketoacyl reductase (KR), acyl carrier protein (ACP), and thioesterase (TE). Although the FAS monomer contains all the activities needed for palmitate synthesis, only the dimer form of the synthase is functional. Both the biochemical analyses and the small-angle neutron-scattering analysis determined that in the dimer form of the enzyme the monomers are arranged in a head-to-tail manner generating two centers for palmitate synthesis. Further, these analyses also suggested that the component activities of the monomer are organized in three domains. Domain I contains KS, AT/MT, and DH, domain II contains ER, KR, and ACP, and domain III contains TE. Approximately one fourth of the monomer protein located between domains I and II contains no catalytic activities and is called the interdomain/core region. This region plays an important role in the dimer formation. Electron cryomicrographic analyses of FAS revealed a quaternary structure at approximately 19 A resolution, containing two monomers (180 x 130 x 75 A) that are separated by about 19 A, and arranged in an antiparallel fashion, which is consistent with biochemical and neutron-scattering data. The monomers are connected at the middle by a hinge generating two clefts that may be the two active centers of fatty acid synthesis. Normal mode analysis predicted that the intersubunit hinge region and the intrasubunit hinge located between domains II and III are highly flexible. Analysis of FAS particle images by using a simultaneous multiple model single particle refinement method confirmed that FAS structure exists in various conformational states. Attempts to get higher resolution of the structure are under way.     

Indium doped silver oxide thin films prepared by reactive electron beam evaporation technique: electrical properties

The indium doped silver oxide thin films have been prepared at 275 °C on soda lime glass and silicon substrates by reactive electron beam evaporation technique; the deposition rate has been varied (by varying the electron beam current) in the range 0.94–16.88 nm/s keeping the oxygen flow rate constant. These films are polycrystalline. The electrical resistivity for these films decreases with increasing deposition rate. The AIO films prepared with a deposition rate of 5.7 nm/s show near p-type conductivity. The work function has been measured on these films by contact potential method using Kelvin Probe. The surface morphology of the films has been evaluated using atomic force microscopy (AFM). The roles of indium doping and oxygen vacancies in the electrical properties of these films have been analyzed; the ionized impurity scattering is the dominant mechanism controlling the electrical conduction in these films.