Identification and decarboxylase activities of bacteria isolated from decomposed mahimahi (Coryphaena hippurus) after incubation at 0 and 32°C

Identification and amine-forming ability of bacterial isolates from decomposed mahimahi (Coryphaena hippurus) were studied in order to identify spoilage microflora and determine the potential for a chemical index of spoilage based on the metabolites produced. Mesophilic bacteria isolated from a fish incubated at 32°C for 24 h were essentially all Gram-negative rods; 89% of these were Vibrio alginolyticus. Strong histamine-forming (> 100 mg/100 ml) mesophiles consisted of eight cultures of Morganella morganii and one of Proteus mirabilis. Weak histamine-forming (< 10 mg/100 ml) mesophiles were all V. alginolyticus, and these comprised 15% of the isolates assigned to that species. Decarboxylation of ornithine and lysine occurred in 38 and 92%, respectively, of the mesophilic isolates. Psychrotrophic isolates obtained from a fish incubated 14 days at 0°C were predominantly Gram-negative genera. Of these, 9% were histamine-forming cultures of Alteromonas putrefaciens, a weak histamine former that produced < 1 mg/100 ml at 5 and 20°C. Decarboxylation of ornithine and lysine occurred in 13 and 15%, respectively, of the psychrotrophic isolates.     

Finite element simulation of plane strain plastic–elastic indentation on single-crystal silicon

Meso-plasticity FEM technique was applied to simulate the dislocation generation and propagation during indentation of a single-crystal silicon. Dislocations were generated and concentrated under the indenter and propagated into the interior of the workmaterial as the indentation progresses. Similarly, the hydrostatic stress and the principal stress were concentrated directly underneath the indenter. The magnitudes of these stresses are found to increase with increase in the depth of indentation. It is proposed that pre-existing microcracks are not necessary for the defect generation in the workmaterial. Instead, a concentration of dislocations generated by plastic deformation under light loads and high hydrostatic pressures can play a similar role. The role of hydrostatic pressure in suppressing fracture was investigated. Based on these studies, it appears feasible to generate crack-free, smooth surfaces below a critical load or cut depth in ultraprecision machining of silicon.     

Preparation of Sm-Ru bimetallic alloy films on Ru(0001) surface by vapour-deposition and annealing

Sm-Ru intermetallic surface alloy films were prepared by vacuum deposition and annealing of rare earth Sm on single crystal Ru(0001) surface. The Ru 3 d and Sm 3 d core level spectra clearly show the formation of surface alloy layers. XPS measurements on surface alloy film revealed an induced peak in the Ru 3 d region at lower binding energy by 1 eV compared to the bulk Ru (elemental) suggesting an electronic effect of alloying and Sm-Ru bond formation. The Sm 3 d _5/2 photoemission peak of Sm film consists of strong features characteristic of Sm(II) with electron configuration 4 f ⁶ (5 d 6 s ) ² and Sm(III) with electron configuration 4 f ⁵ (5 d 6 s ) ³ .It is observed that the Sm(II) feature decreases in intensity upon alloy formation with surface Ru atoms. Oxidation of these films with carbon monoxide indicates alloy breakdown due to the oxidation of Sm atoms selectively. Alloy oxidation also shows a clear shift of Sm 3 d _5/2 feature.     

Characterization of combustion synthesized zirconia powder by UV-vis, IR and other techniques

Fine powders of zirconia were prepared by employing combustion method with varying fuel to pre-cursor molar ratios. The zirconia powders contained more amount of monoclinic phase as the fuel content was increased. This aspect was studied using XRD, IR and UV-vis diffuse reflectance techniques. The surface acid-base properties of these samples were also investigated by indicator titration method. The catalytic activity was probed with transfer hydrogenation reaction in liquid phase. It was found that combustion synthesized zirconia did not provide required active sites for transfer hydrogenation reactions in liquid phase unlike hydrous zirconia.     

Genetic algorithms applied to the continuous flow shop problem

This research develops an approach for applying Genetic Algorithms (GA) to scheduling problems. We generate a GA based heuristic for continuous flow shop problems with total flow time as the criterion. The effects of several crucial factors of GA on the performance of the heuristic for the problem are explored in detail. The computational experience of heuristic provides several observations of the application of GA, and strongly supports that the applications of GA are problem specific. The computational experience also shows that GA can be good techniques for scheduling problems.     

Diagnosis of malaria--an overview

PURPOSE: To examine the anterior optic nerve vasomotor effects of nonselective and relatively beta-1-selective beta-adrenergic antagonists in rabbits, because different influences on optic nerve blood flow with these medications have been suggested. METHODS: After topical therapy for 30 days with either timolol maleate 0.5% (six rabbits), betaxolol hydrochloride 0.5% (six rabbits), or placebo (two rabbits), the microvasculature of the optic nerve was examined with an intraluminal microvascular corrosion casting technique. The investigators were masked to both the medication group and the treated eye. The constriction, in percent of the downstream vessel caliber, was measured at the vascular branching point of arterioles supplying the anterior optic nerve. An average constriction was calculated and compared between the medication groups and between the treated and the contralateral, untreated eyes. RESULTS: Constriction values from a total of 218 arterioles supplying the anterior optic nerve were obtained for the 14 rabbits. The means of the average constriction on the treated side were comparable between the groups treated with timolol maleate, betaxolol hydrochloride, and placebo (one-way analysis of variance, P = .64), as well as between the treated and untreated eyes (two-tailed t-test for paired variables, P = .68 for timolol maleate and P = .42 for betaxolol hydrochloride). The statistical power to find a difference of 5% or more average constriction was at least 90%. CONCLUSIONS: Both relatively selective and nonselective beta-adrenergic antagonists produce no observable optic nerve vasomotor effects in the rabbit eye.     

Frequency and time domain analyses of sensor signals in drilling—II. Investigation on some problems associated with sensor integration

Sensor integration has received considerable attention recently for monitoring machining processes. This is because it is similar to the action of an experienced machinist, who uses his different sensory devices such as hearing, sight, etc. to monitor the cutting operation. Different neural network paradigms have been attempted by researchers for this purpose. In this investigation, a multisensor approach to drill wear monitoring was studied. Four sensors, namely, thrust, torque, and strains on the machine table in two orthogonal directions perpendicular to the drill axis, were used. As shown in Part I [A. Noori-Khajavi and R. Komanduri, Int. J. Mach. Tools Manufact. 35, 000-000 (1995)] three sensor signals, namely, thrust, torque, and strain on the machine table in the X-direction, showed good correlation in the frequency domain with drill wear. In addition, the signal-to-noise ratio analysis at different states of drill wear in the frequency domain showed that as the drill wear increased, the noise also increased. In this paper, it will be shown that when sensor signals are noisy and are integrated using a neural network, such a system could actually result in the deterioration of the correct estimation of drill wear. Consequently, there appears to be no need for the integration of the sensor signals under the conditions used.     

On friction and metal transfer of sliding surfaces undergoing subsurface plastic deformation

Results of sliding experiments under high normal pressure using a sapphire ball on a modified Brinell hardness testing machine and different work materials are reported. A rational approach to the mechanism of metal build-up on Al₂O₃ abrasive developed recently has been extended in the present sliding tests to verify the hypothesis, and good agreement was found. The results of this study show a wide range of behaviour relative to the equilibrium level of friction and the time required to reach equilibrium when different materials are rubbed against the sapphire ball.     

Cerium Containing Al- and Zr-Pillared Clays: Promoting Effect of Cerium (III) Ions on Structural and Catalytic Properties

Ce³⁺ containing Al- and Zr-pillared clays were prepared by co-hydrolysis and co-intercalation methods, respectively. The materials were characterized by XRD, IR and near IR techniques. The expansion in the clay lattice as a result of pillaring was confirmed from X-ray diffraction study. The basal spacing for the pillared clay materials was observed typically in the range of 18–23 Å. The IR and near IR studies were employed to show the presence of acidic and non-acidic hydroxyl groups in the pillared clays. The IR peak at 3630 cm⁻¹ corresponding to the structural hydroxyl groups was more intense in pillared clays than in the parent clay. This peak is retained even after calcination at 500^∘C. Various overtone and combination bands were observed in the NIR range of 1200–2500 nm for the pillared clay materials. Pillaring with Al- and Zr-inorganic polycations enhanced the catalytic activity of the parent clays for dehydration of cyclohexanol. The presence of Ce³⁺ ions in the pillared clays was found to influence catalytic activity and stability of the Brønsted acidic sites. The stabilizing effect of cerium ion in the pillared clays is attributed to the competitive site occupancy and prevention of octahedral migration of the catalytically active protons.