Chloromycetin in the nutrition of the silkworm Bombyx mori L.-III. Influence on gut weight, oxygen uptake, and glucose absorption

Administration of chloromycetin has been found to enhance the oxygen uptake of the gut of the silkworm. The possibility that this increase might have been due to a thinning of the gut wall has been ruled out since the reduction in gut weight set in much later. Although glucose ultilization by the gut has been found to be increased in vitro, increase in oxygen uptake has not been affected in the presence of glucose. The possibility of a hormonal stimulation has been discussed.

Chemical potentials of oxygen for fayalite-quartz-lron and fayalite-quartz-magnetite equilibria

The oxygen potentials corresponding to fayalite-quartz-iron (FQI) and fayalite-quartz-magnetite (FQM) equilibria have been determined using solid-state galvanic cells: Pt,Fe + Fe2SiO4 + SiO2/(Y2O3)ZrO2/Fe + \r"FeO,\l"Pt and Pt, Fe3O4 + Fe2SiO4 + SiO2/(Y2O3)ZrO2/Ni + NiO, Pt in the temperature ranges 900 to 1400 K and 1080 to 1340 K, respectively. The cells are written such that the right-hand electrodes are positive. Silica used in this study had the quartz structure. The emf of both cells was found to be reversible and to vary linearly with temperature. From the emf, Gibbs energy changes were deduced for the reactions: 0.106Fe (s) + 2Fe0.947O (r.s.) + SiO2 (qz) → Fe2SiO4 (ol) δG‡= -39,140+ 15.59T(± 150) J mol-1 and 3Fe2SiO4 (ol) + O2 (g) → 2Fe3O4 (sp) + 3SiO2 (qz) δG‡ = -471,750 + 160.06 T±} 1100) J mol-1 The “third-law≓ analysis of fayalite-quartz-wustite and fayalite-quartz-magnetite equilibria gives value for δH‡298 as -35.22 (±0.1) and -528.10 (±0.1) kJ mol-1, respectively, independent of temperature. The Gibbs energy of formation of the spinel form of Fe2SiO4 is derived by com-bining the present results on FQI equilibrium with the high-pressure data on olivine to spinel transformation of Fe2SiO4.

Stress induced phase transition in monomolecular perfluroalkylsilane film self assembled on aluminium surface

We control the stiffnesses of two dual double cantelevers placed in series to control penetration into a perflurooctyltrichlorosilane monolayer self assembled on aluminium and silicon substrates. The top cantilever which carries the probe is displaced with respect to the bottom cantilever which carries the substrate, the difference in displacement recorded using capacitors gives penetration. We further modulate the input displacement sinusoidally to deconvolute the viscoelastic properties of the monolayer. When the intervention is limited to the terminal end of the molecule there is a strong viscous response in consonance with the ability of the molecule to dissipate energy by the generation of gauche defects freely. When the intervention reaches the backbone, at a contact mean pressure of 0.2GPa the damping disappears abruptly and the molecule registers a steep rise in elastic modulus and relaxation time constant, with increasing contact pressure. We offer a physical explanation of the process and describe this change as due to a phase transition from a liquid like to a solid like state.

Probabilistic Analysis of Cracking Moment of Reinforced Concrete Beams

Probabilistic analysis of cracking moment from 22 simply supported reinforced concrete beams is performed. When the basic variables follow the distribution considered in this study, the cracking moment of a beam is found to follow a normal distribution. An expression is derived, for characteristic cracking moment, which will be useful in examining reinforced concrete beams for a limit state of cracking.

Growth of and trehalase activity in the thermophilic fungusThermomyces lanuginosus

The thermophilic fungus,Thermomyces lanuginosus, was grown in a glucose-asparagine liquid medium. Optimal mycelial growth occurred at 50°C. The conditions for sporulation were different from those required for vegetative growth. the former being favoured by lower nitrogen level and temperature. Trehalase (α, α-glu coside-l-glucohydrolase, EC 3.2.1.28) was one of the most active glycosidases at 50°C. Non-sporulating mycelium had higher levels of this enzyme than the sporulating mycelium. Trehalase was synthesized constitutively and its activity appears to be controlled by catabolite repression.

Crystal structure and ionic conductivity of a new bismuth tungstate,Bi3W2O10.5

The compound Bi3W2O10.5 was synthesized by the solid-state technique from Bi2O3 and WO3 in stoichiometric quantities. Single crystals were grown by the melt-cooling technique and the crystal structure was solved in the tetragonal 141in space group with a = 3.839 (1) A, c = 16-3S2 (5) A, V = 241.4 (1) angstrom(3), Z = 4 and was refined to an R index of 0.0672. The structure represents a modification of the Aurivillius phase and consists of [Bi2O2](2+) units separated by WO8 polyhedra. a.c. impedance studies indicate oxide ion conductivity of 2.91 10(-5) cm(-1) at 600 degrees C.

Splittings of free groups, normal forms and partitions of ends

Splittings of a free group correspond to embedded spheres in the 3-manifold M = # (k) S (2) x S (1). These can be represented in a normal form due to Hatcher. In this paper, we determine the normal form in terms of crossings of partitions of ends corresponding to normal spheres, using a graph of trees representation for normal forms. In particular, we give a constructive proof of a criterion determining when a conjugacy class in pi (2)(M) can be represented by an embedded sphere.

Upper mass limit for neutron star stability against black hole formation

Starting from the exact general relativistic expression for the total energy of selfgravitating spherically distributed matter and using the minimum energy priciple, we calculate the upper mass limit for a neutron star to be 3.1 solar masses.

Laser-fused refractory oxides for optical coatings

Laser sintering was carried out using a high power continuous-wave CO2 laser to prepare pellets of zirconia (ZrO2), hafnia (HfO2) and yttria (Y2O3) mixed oxides as starting materials in the deposition of optical coatings. Hardened recrystallized pellets appeared to have been formed during laser treatment. X-ray diffraction analysis revealed a monoclinic-to-tetragonal phase transformation in the binary system while the ternary system was found to have a mixture of two crystalline phases. Cross-sectional scanning electron microscopy showed two isothermal crystalline regions in the ternary system. The optical inhomogeneity was low in the films deposited from the laser-fused pellets, but the absorption at a wavelength of 351 nm increased with increasing HfO2 content. The films deposited from laser-fused pellets were analysed by electron spectroscopy for chemical analysis and found to be stoichiometric and homogeneous.

Optimization of an ammonia reactor using regression analysis

This paper presents an optimization algorithm for an ammonia reactor based on a regression model relating the yield to several parameters, control inputs and disturbances. This model is derived from the data generated by hybrid simulation of the steady-state equations describing the reactor behaviour. The simplicity of the optimization program along with its ability to take into account constraints on flow variables make it best suited in supervisory control applications.

A Direct Approach to the Problem of Diffraction by a Half-Plane under Mixed Boundary Conditions

A general direct technique of solving a mixed boundary value problem in the theory of diffraction by a semi-infinite plane is presented. Taking account of the correct edge-conditions, the unique solution of the problem is derived, by means of Jones' method in the theory of Wiener-Hopf technique, in the case of incident plane wave. The solution of the half-plane problem is found out in exact form. (The far-field is derived by the method of steepest descent.) It is observed that it is not the Wiener-Hopf technique which really needs any modification but a new technique is certainly required to handle the peculiar type of coupled integral equations which the Wiener-Hopf technique leads to. Eine allgemeine direkte Technik zur Lösung eines gemischten Randwertproblems in der Theorie der Beugung an einer halbunendlichen Ebene wird vorgestellt. Unter Berücksichtigung der korrekten Eckbedingungen wird mit der Methode von Jones aus der Theorie der Wiener-Hopf-Technik die eindeutige Lösung für den Fall der einfallenden ebenen Welle hergeleitet. Die Lösung des Halbebenenproblems wird in exakter Form angegeben. (Das Fernfeld wurde mit der Methode des steilsten Abstiegs bestimmt.) Es wurde bemerkt, daß es nicht die Wiener-Hopf-Technik ist, die wirklich irgend welcher Modifikationen bedurfte. Gewiß aber wird eine neue Technik zur Behandlung des besonderen Typs gekoppelter Integralgleichungen benötigt, auf die die Wiener-Hopf-Technik führt.

Gibbs energy of formation of orthorhombic CaZrO3

The Gibbs free energy of formation of the orthorhombic form of CaZrO3(o) from monoclinic ZrO2(m) and periclase CaO(p) has been determined as a function of temperature in the range 950-1225 K, using an electrochemical cell incorporating single-crystal CaF2 as the solid electrolyte. The results are corrected for the small solid solubility of CaO in ZrO2. For the reaction, ZrO2(m) + CaO(p) --> CaZrO3(o), DELTAG(phi) = -31590 -13.9T(+/- 180) J mol-1. The ''second-law'' enthalpy of formation of CaZrO3 obtained from the results of this study at a mean temperature of 1090 K is in excellent agreement with the high-temperature solution calorimetric measurements of Muromachi and Navrotsky at 1068 K (J. Solid State Chem., 72 (1988) 244), and the average value of the bomb and acid solution calorimetric studies of Lvova and Feodosev (Zh. Fiz. Khim., 38 (1964) 28), Korneev et al. (Izv. Akad. Nauk SSSR, Neorg. Mater., 7 (1971) 886) and Brown and Bennington (Thermochim. Acta, 106 (1986) 183). The standard entropy of CaZrO3(o) at 298.15 K from the free energy data is 96.4 (+/- 3.5) J K-1 mol-1. The results of this study are discussed in comparison with high-temperture e.m.f. measurements reported in the literature on cubic zirconia solid solutions.

An Efficient Random Walk Strategy for Sampling Based Robot Motion Planners

Sampling based planners have been successful in path planning of robots with many degrees of freedom, but still remains ineffective when the configuration space has a narrow passage. We present a new technique based on a random walk strategy to generate samples in narrow regions quickly, thus improving efficiency of Probabilistic Roadmap Planners. The algorithm substantially reduces instances of collision checking and thereby decreases computational time. The method is powerful even for cases where the structure of the narrow passage is not known, thus giving significant improvement over other known methods.