Probing the existing magnetic phases in Pr0.5Ca0.5MnO3 (PCMO) nanowires and nanoparticles: magnetization and magneto-transport investigations

We show from conventional magnetization measurements that the charge order (CO) is completely suppressed in 10 nm Pr0.5Ca0.5MnO3 (PCMO 10) nanoparticles. Novel magnetization measurements, designed by a special high field measurement protocol, show that the dominant ground state magnetic phase is ferromagnetic-metallic (FM-M), which is an equilibrium phase, which coexists with the residual charge ordered anti-ferromagnetic phase (CO AFM) (an arrested phase) and exhibits the characteristic features of a `magnetic glassy state' at low temperatures. It is observed that there is a drastic reduction in the field required to induce the AFM to FM transition (similar to 5-6 T) compared to their bulk counterpart(similar to 27 T); this phase transition is of first order in nature, broad, irreversible and the coexisting phases are tunable with the cooling field. Temperature-dependent magneto-transport data indicate the occurrence of a size-induced insulator-metal transition (TM-I) and anomalous resistive hysteresis (R-H) loops, pointing out the presence of a mixture of the FM-M phase and AFM-I phase.

Open-access more harm than good in developing world

The traditional 'publish for free and pay to read' business model adopted by publishers of academic journals can lead to disparity in access to scholarly literature, exacerbated by rising journal costs and shrinking library budgets. However, although the 'pay to publish and read for free' business model of open-access publishing has helped to create a level playing field for readers, it does more harm than good in the developing world.

Handling sectional views in volume-based approach to automatically construct 3D solid from 2D views

This paper presents an algorithm for solid model reconstruction from 2D sectional views based on volume-based approach. None of the existing work in automatic reconstruction from 2D orthographic views have addressed sectional views in detail. It is believed that the volume-based approach is better suited to handle different types of sectional views. The volume-based approach constructs the 3D solid by a boolean combination of elementary solids. The elementary solids are formed by sweep operation on loops identified in the input views. The only adjustment to be made for the presence of sectional views is in the identification of loops that would form the elemental solids. In the algorithm, the conventions of engineering drawing for sectional views, are used to identify the loops correctly. The algorithm is simple and intuitive in nature. Results have been obtained for full sections, offset sections and half sections. Future work will address other types of sectional views such as removed and revolved sections and broken-out sections. (C) 2004 Elsevier Ltd. All rights reserved.

Effect of ICSH on Early Pregnancy in Hypophysectomized Pregnant Rats

Moudgal and co-workers1-3 recently reported that the administration to intact pregnant rats of rabbit antiserum ovine interstitial cell stimulating hormone (ICSH) on any one day between the eighth and twelfth days of pregnancy resulted in resorption of foetuses and termination of pregnancy. This effect was readily reversed by the simultaneous administration of progesterone but not by oestradiol-17β. These observations suggested that ICSH was involved in progesterone synthesis and as such is a luteotropic factor in the rat.

Fine Structure of the Rayleigh Line in Amorphous Substances

As is well known, when monochromatic light scattered by a liquid is examined under high resolution it exhibits a fine structure: an undisplaced central line and two lines on either side with wavelengths slightly different from that of the incident light. The appearance of the displaced components was first predicted by Brillouin1. On the basis of his theory, the observed displacements of frequency are regarded as a Doppler effect arising from the reflexion of the light wave by the progressive sound waves of thermal origin in the scattering medium. The frequency shift of the so-called Brillouin components is given by the formula where nu and c are the velocities of sound and light in the medium and theta is the angle of scattering. That the effect contemplated by Brillouin does arise in liquids and crystals is now a well-established experimental fact.

Effect of anti-luteinizing hormone serum on the ovulation of rats

IN the cyclic female albino rat, a release of pituitary luteinizing hormone (LH) occurs on the afternoon of proestrus1-5. This apparently induces ovulation, for ova are seen in the Fallopian tube 12 h later. Similarly, it is well known that in immature rats primed with pregnant mare serum gonadotrophin (PMS), ovulation can be induced by the administration of human chorionic gonadotrophin (HCG) or LH, the ova being seen in the Fallopian tube 12 h later. No information is available, however, about the mode of action of LH, released or administered, in bringing about ovulation. We have approached this problem by blocking the action of the ovulating hormone (LH) at various times after administration. © 1970 Nature Publishing Group.

Biosynthesis of valine and isoleucine in plants II. Dihydroxyacid dehydratase from Phaseolus radiatus

1. 1. An enzyme catalysing the conversion of α,β-dihydroxyisovalerate and α,β-dihydroxy-β-methylvalerate to α-ketoisovalerate and α-keto-β-methylvalerate has been partially purified from green gram (Phaseolus radiatus), and its characteristics studied. 2. 2. A natural inhibitor, heat stable and inorganic in nature, was observed in the crude extracts. 3. 3. The observed Km values for α-β-dihydroxyisovalerate and α,β-dihydroxy-β-methylvalerate were 2.4 · 10-3 M and 9 · 10-4 M, respectively. 4. 4. The enzyme required the presence of a divalent metal ion (Mg2+, Mn2+ or Fe2+) for maximal activity. Heavy metals like Ag+ and Hg2+ were inhibitory. 5. 5. The optimal activity was around pH 8.0 and the optimum temperature at 52°. The activation energy is found to be 12 600 cal/mole. 6. 6. The enzyme was inhibited by p-hydroxymercuribenzoate, N-ethylmaleimide and sulphydryl compounds like cysteine, glutathione, 2-mercaptoethanol and 2,3-dimercaptopropanol. The inhibition by p-hydroxymercuribenzoate could not be reversed by any of the sulfhydryl compounds tested.

Transduction in mycobacterium smegmatis

SEVERAL people have studied lysogeny and lysogenic conversion in the advanced prokaryote, Mycobacterium1-3, and presented evidence for reciprocal genetic exchange from the lysogenic to the non-lysogenic state. Biochemical and physiological changes induced by lysogenization of M. phlei with mycobacteriophage B2 have been demonstrated by Juhasz4. We wish to report the isolation of a mycobacteriophage capable of mediating transduction in Mycobacterium smegmatis strain SN2, thus providing an opportunity to study the genetics of mycobacteria.

Infra-red absorption bands of co-ordinated water in titanium complexes

ORANGE red and amorphous peroxy-titanium complexes of oxalic, malonic and maleic acids1-3, when vacuum-dried, have co-ordinated water molecules firmly bonded to the central titanium atom as shown in formula (I). The peroxy-oxygen from these compounds is slowly lost even at room temperature because of the strained peroxy-group3,4. The compounds, when kept at 95°-100°C. for about three days, give deperoxygenated compounds of the type (II). However, a sample of peroxy-titanium oxalate sealed in a glass tube lost all its peroxy-oxygen in about four years and gave a white crystalline basic oxalate (II). The amorphous nature of the compounds may be due to random hydrogen bonding in the complexes. The crystallinity observed in one of the deperoxygenated titanyl oxalates may be due to the rearrangement of the molecules during ageing for more than four years. The infra-red absorption of these compounds was studied to find out the effect of co-ordination and hydrogen bonding on the infra-red bands of the free water.

Fatty acid specificity for the esterification of vitamin A and cholesterol by intestinal and pancreatic enzymes in rats

VITAMIN A and cholesterol esters have been shown to undergo extensive hydrolysis in the lumen of the small intestine during the process of absorption; they are re-esterified to appear in the lymph mostly as esters1,2. However, the vitamin A esters of the lymph, blood and liver of the rat are formed by long-chain fatty acids3 and in the normal rat liver, probably as palmitates4. On the other hand, cholesterol esters are usually made up of poly-unsaturated fatty acids in the lymph and blood of rats5. For the absorption of the two lipid materials, the enzymes of the pancreas have been largely implicated, while not much attention has been paid to the possible role of the mucosal enzymes. From the behaviour of the mucosal enzymes, as presented here, it appears that probably these enzymes play a more important part in the re-esterification of the two lipid materials during their absorption.

Distribution of coenzyme Q in rat liver cell fractions

COENZYME Q (CoQ), which is widely distributed in animal, plant and microbial sources, has been implicated in electron transport1 and generally assumed to be associated with mitochondria. However, it has also been found in non-mitochondrial fractions of green leaves, although it appears to be concentrated in mitochondria2. A similar distribution has now been demonstrated in rat liver cell fractions.

Comparative studies of transient and steady state analysis for a typical 765kV/400kV EHV transmission system in Indian power system

This paper describes an approach for the analysis and design of 765kV/400kV EHV transmission system which is a typical expansion in Indian power grid system, based on the analysis of steady state and transient over voltages. The approach for transmission system design is iterative in nature. The first step involves exhaustive power flow analysis, based on constraints such as right of way, power to be transmitted, power transfer capabilities of lines, existing interconnecting transformer capabilities etc. Acceptable bus voltage profiles and satisfactory equipment loadings during all foreseeable operating conditions for normal and contingency operation are the guiding criteria. Critical operating strategies are also evolved in this initial design phase. With the steady state over voltages obtained, comprehensive dynamic and transient studies are to be carried out including switching over voltages studies. This paper presents steady state and switching transient studies for alternative two typical configurations of 765kV/400 kV systems and the results are compared. Transient studies are carried out to obtain the peak values of 765 kV transmission systems and are compared with the alternative configurations of existing 400 kV systems.

Nature of hydrogen atom trapped inside palladium lattice

Colloid of palladium nanoparticles has been prepared by the Solvated Metal Atom Dispersion (SMAD) method. Reaction of Pd(0) nanopowder obtained upon precipitation from the colloid, with ammonia borane (H3N center dot BH3, AB) in aqueous solutions at room temperature results in the generation of active hydrogen atoms. The active hydrogen atoms either combine with one another resulting in H-2 evolution or diffuse into the Pd lattice to afford PdHx. Diffusion of hydrogen atoms leads to an expansion of the Pd lattice. The diffused hydrogen atoms are distributed uniformly over the entire particle. These features were established using powder XRD and electron microscopy studies. The H-1 NMR spectral studies of PdHx before and after desorption of H-2 revealed that the hydrogen atoms trapped inside Pd lattice are hydridic in nature. Desorption of hydrogen from PdHx did not result in complete reversibility suggesting that some hydrogen atoms are strongly trapped inside the Pd lattice. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.