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The bond constraint theory (BCT) dealing with the rigidity caused by bond constraints and the long-range potential fluctuations (LRPF) arising from the defects and heterogeneities in the disordered semiconductors are important for understanding the atomic and electronic properties of amorphous semiconductors. Here, they are applied to the already commercialized Ge X Sb Y Te1 − X − Y (GST) chalcogenide glasses used in the rewritable phase change memory (PCM) devices. The main concern at present is to improve their ability to withstand a large number of phase change cycles, by choosing the right composition. The two considerations (BCT and LRPF) are briefly described and tested on the most commonly used Ge2Sb2Te5 and the nearby compositions. While these considerations provide significant insight into their atomic and electronic structures, the ansatz linking them with the durability of the PCM devices need to be justified by more work.

The inhomogeneities present in hydrogenated amorphous silicon (a-Si : H) give rise to potential fluctuations. They influence the electronic properties of a-Si : H in a profound manner. Nevertheless, very few theoretical and experimental studies acknowledge their presence, because of the inherent difficulties in dealing with them. We find that the width of the potential fluctuations obtained from transport measurements is much smaller than that obtained by optical methods. This may be because the former (transport) depends on long-range potential fluctuations, whereas the latter is sensitive to short-range ones. External perturbations, e.g. light soaking and thermal quenching, are found to have different effects on the long-range potential fluctuations. Light soaking (the Staebler–Wronski effect) seems to increase them, whereas thermal quenching leaves them unchanged.

Biological Properties of Avian Mycoplasma Species in India

The electronic structure of hydrogenated amorphous silicon (a-Si:H) is in a state of metastable equilibrium and can change upon application of external stimuli. We study the effect of thermal quenching and light soaking in lithium-doped a-Si:H, on its conductivity and thermopower. We present evidence showing that the metastable state obtained after fast quenching is different than that obtained after light exposure. Experiments on chalcogenides show that they are not affected by thermal quenching although they change upon light soaking. This is in contrast with lithium doped a-Si:H in which both effects are observed. Our experiments suggest that hydrogen present in a-Si:H plays an important role by controlling heterogeneities and potential fluctuations in a-Si:H. Light soaking appears to enhance these potential flucutations, whereas fast cooling seems to have little effect on them.

In this paper we report on the growth of polycrystalline diamond films on Mo, W, and Ni substrates using oxy-acetylene combustion flame technique. Effect of substrate temperature on the growth of diamond films has been studied in the temperature range 600–1100°C. The deposits and their surface morphology has been characterized by X-ray diffraction and scanning electron microscopy (SEM). A short duration pretreatment of Mo substrates by outer zone of the oxy-acetylene flame at lower substrate temperatures, results in the improvement of quality and adherence of the films. Growth of diamond as well as other intermediate compounds depending on the nature of substrates and interface layers is discussed.

The hydrogen in hydrogenated amorphous silicon (a-Si: H) makes it behave like a hydrogen glass. Above a temperatureTE, which is analogous to the glass transition temperature, the hydrogen is able to move more freely than belowTE. This motion of hydrogen is believed to be responsible for the observed thermal and light induced metastabilities in a Si: H. However, the changes in the microstructure of the bonded hydrogen upon thermal quenching are found to influence the electronic properties of a-Si: H, in a manner, which is different from light soaking. Our studies suggest that the light soaking changes the potential fluctuations in lithium doped a-Si: H, whereas the thermal quenching does not.

The effect of light soaking and thermal quenching on the electronic structure of hydrogenated amorphous silicon (a-Si:H) and chalcogenide glasses was studied. It was found that lithium dopeda-Si:H shows both light and thermal induced changes in electronic transport properties. In contrast, chalcogenides do not show any effect of thermal quenching, although they exhibit changes upon light soaking. By analysing the conductivity and thermopower data we have concluded that the light soaking increases the potential fluctuations present in lithium dopeda-Si:H, whereas quenching does not change them. A model qualitatively explaining these effects is presented.

Synthesis and some interesting properties of amorphous silicon-based superlattices are reported. Both quantum-well type and doping modulated structures are studied. Quantum confinement, phonon folding and persistent photoconductivity are some of the fascinating effects which are described and their current interpretations discussed.

Lac Processing & Product Development Division, Indian Lac Research Institute, Namkum, Ranchi-834 010, Jharkhand, India E-mail : lppd@ilri.ernet.in Fax : 91-0651-2260202 Manuscript received 17 February 2006, revised 13 July 2006, accepted 25 August 2006 (E)-7-Hexadecen-1,16-olide (ambrettolide), having musk-like odour being used as a fixative in perfumery industry. It was synthesized from \(threo\)-aleuritic acid (9,10,16-trihydroxyhexadecanoic acid) by simple procedure.

A new extended x-ray-absorption fine structure spectroscopy study of local bonding identifies for the first time significant concentrations of Ge-Ge bonds in amorphous ${\mathrm{Ge}}_{2}{\mathrm{Sb}}_{2}{\mathrm{Te}}_{5}$. The study provides a new understanding of the local molecular structure of this phase-change material. Application of bond constraint theory indicates that the amorphous phase is an ideal network structure in which the average number of constraints per atom equals the network dimensionality. Analysis within this framework imparts new and significant insights concerning the nature of the reversible optically driven amorphous-crystalline phase transition of ${\mathrm{Ge}}_{2}{\mathrm{Sb}}_{2}{\mathrm{Te}}_{5}$.

Conversion of benzaldehyde to L-phenylacetyl carbinol (L-PAC) was achieved with immobilized, growing cells of Saccharomyces cerevisiae in different reactors. Product formation increased (31%) with the subsequent initial reuses of the entrapped cells. Biomass production and PAC formation depleted (40 and 57%, respectively) after 4-5 continuous growth and biotransformation cycles. With the regeneration of the biocatalysts, catalytic activity of the cells was resumed. The highest yields were in a stirred tank reactor (29 g PAC) from 77 g benzeldehyde with 14 repeated uses of entrapped cells.

A simple and compact arrangement for flash evaporation is described. It uses a cell phone vibrator for powder dispensing that can be incorporated into a vacuum deposition chamber without any major alterations. The performance of the flash evaporation system is checked by making thin films of the optical memory chalcogenide glass Ge2Sb2Te5 (GST). Energy dispersive x-ray analysis shows that the flash evaporation preserves the stoichiometry in thin films.

Production of L-phenylacetylcarbinol (L-PAC) through biotransformation of benzaldehyde by free and immobilized cells of the yeast Saccharomyces cerevisiae has been attempted. L-PAC production was found to be maximum (0.4 microliter/ml) when anaerobically grown free cells were used as biocatalyst during aerobic biotransformation for two hours with magnetically stirred bioreactor. Growth under oxygen limited conditions led to accumulation of higher amount of pyruvate decarboxylase enzyme and co-substrate, pyruvate, resulting in higher L-PAC formation. L-PAC yield was low when biotransformations were carried out anaerobically either for aerobically or anaerobically grown free cells. Free cells were found to be more efficient biocatalyst for L-PAC production, as compared with the immobilized cells, with the investigated benzaldehyde concentration (0.3% v/v) and cell density (17.5% w/v). The study has explored and indicated the possibility of optimizing the yield of L-PAC by growing the yeast cells under oxygen limited condition for suitable aerobic mode of benzaldehyde biotransformation.

Exposure to ammonia (NH3) increases the dark current (DC) in nanocrystalline silicon. Light soaking (LS) for short periods also enhances the dark current, which remains at a high value for a long time. Pumping alone is unable to restore the initial annealed state, but annealing brings it back. The final state obtained by LS and NH3 exposure depends on the order in which they are performed. Evaporated selenium (Se) deposited on nanocrystalline silicon decreases the DC. These effects cannot be explained entirely by the presence of a-Si : H alone, in our sample. DC and photoluminescence (PL) measurements indicate the presence of two types of center in our sample, which behave differently when exposed to NH3.

Invitro antimycotic effect of the coconut, mustard, groundnut & soyabeen oils and the seeds of trigonella, ajwoin, mustard and garlic bulbs were mixed in the above oil samples to determine their effect on the spore germination of five pathogenic fungi i.e., Aspergillus niger, A.flavus, Absidia corymbifera, Penicilium nigricans and Candida albicans, isolated from otitic fungal infection of external ear (tympanic membrane) of human beings of different places. Growth of these fungi was completely inhibited by the oil of mustard when mixed seeds of trigonella, ajwoin, mustard and garlic bulbs, while coconut oil with ajwoin seeds was found to be less funitoxic. In addition to these other oils and different plant parts were also found to have fungitoxicity against test pathogens and increase pf 50 – 100 percent inhibition was noted in these cases. Present study indicated the possible role of test oils and different plant parts in control of otomycosis in human being after further experimental in-vivo condition.

We have studied adduct formation of the antineoplastic agent diaziquone (AZQ; NSC 182986) with DNA and nucleotides in vitro. The aziridine moieties of AZQ can be expected to interact covalently with DNA which, in turn, presumably elicits the antitumor activity. We analyzed AZQ-DNA adducts by a modified 32P-postlabeling assay involving purification of the nuclease P1-enriched labeled adducts by high-salt C18 reversed-phase thin-layer chromatography and separation of the eluted adducts on a polyethyleneimine-cellulose layer using non-urea salt solutions. Modification of calf thymus DNA with AZQ produced two major (22% and 40%) and at least eight minor adducts. At equal concentrations of AZQ and DNA (1 micrograms/microliters each), peak binding was observed in about 2 h [1926 +/- 378 (SD) fmol/micrograms of DNA] with the binding levels remaining practically unchanged through 4 h. However, incubation for 24 h resulted in over 40% decline, indicating adduct instability. AZQ was found to be highly reactive in vitro as evidenced by its substantial binding (49 +/- 14 fmol/micrograms of DNA) even at a DNA:AZQ ratio of 100:1. When incubated with mononucleotides, AZQ reacted extensively with adenine, guanine, and cytosine but only slightly with thymine. Cochromatography of the modified DNA and nucleotides revealed that one of the major adducts and several minor adducts were guanine derived. The aziridine rings of AZQ were found to be the main reactive sites as its monoaminoalcohol derivative showed as much DNA reactivity as did the parent compound, but no activity was observed when both aziridine groups were hydrolyzed to diaminoalcohols. The improved 32P-postlabeling assay seems capable of detecting relatively polar adducts such as those formed with AZQ at a level of one adduct/10(9) nucleotides.

Experimental mycetoma-like lesions developed in guinea pigs after subcutaneous injection of Nocardia asteroides. Although delayed hypersensitivity appeared earlier, increased macrophage migration inhibition and microbicidal activity appeared after 7 weeks. When the lesions healed, high cell-mediated immunity was present. Cell-mediated immunity was transferred to normal recipient guinea pigs from healed donor guinea pigs by spleen cell transfer. Recipient guinea pigs showed marked protection against challenge with N. asteroides.

A dc glow discharge apparatus for preparing amorphous silicon films from silane gas is described. The films are characterized by electron microscopy, infrared spectroscopy, electrical conductivity and photoconductivity. The deposition parameters which give good photoconducting films are established. The Staebler-Wronski effect is studied and is found to be smaller in vacuum than in air. A photovoltage is observed in structures with gold as the Schottkybarrier metal. The conversion efficiency of the device is about 1%. The results are compared with those in the literature, and the improvements which might result in a better conversion efficiency are pointed out.

Guinea pigs immunized with ribonucleic acid protein fraction from Nocardia asteroides developed high cell-mediated immunity within 2 weeks, as shown by increased macrophage microbicidal activity and macrophage migration inhibition. This immunity protected against intravenous and subcutaneous challenge with N. asteroides and persisted for at least 70 days.

The formation and decomposition behaviour of metastable structures in liquid-quenched (LQ) Ag-Ge alloys was studied with X-ray diffraction, resistivity measurements and TEM techniques. Pure Ag and alloys containing 7, 10, 15, 20 and 22.5 at. % Ge were studied. Upon LQ, pure Ag and 7 and 10 at. % Ge alloys yield a single f cc phase; 15 and 20 at. % Ge alloys give a mixture of two metastable phases (f cc and h cp); and the Ag-22.5 at. % Ge alloy gives a metastable h cp phase. Also, the first evidence of an amorphous phase in as-LQ Ag-22.5 at. % Ge alloy is presented. It is shown that Ag-rich f cc phase can retain up to ∼ 20at. % Ge in solid solution. Furthermore, stacking faults play an important role in the formation and decomposition of metastable phases in the Ag-Ge system.

Marked in vivo intracellular killing of Nocardia asteroides occurred in the peritoneal macrophages obtained 72 h after an intraperitoneal challenge with N. asteroides, in guinea pigs either actively immunized with ribonucleic acid protein or passively immunized by immune spleen cell transfer from actively immunized donor guinea pigs. This specific killing of N. asteroides in immune macrophages persisted for at least up to 60 days. Administration of antimacrophage sera before intravenous challenge with N. asteroides in the immune guinea pigs produced an early death of the animals, and the total tissue counts of N. asteroides in the liver, spleen, lungs, and heart remained the same in them as in unimmunized controls.

We propose a model of the thin films of a-Ge and a-Si with microvoids as frustrated spin glasses. Within this model the various qualitative aspects of the experimental results can be reasonably explained.

Two hundred and sixty-four samples of sera obtained from normal healthy persons belonging to different age groups were examined for haemagglutination-inhibiting antibodies against reovirus types 1–3 to assess the prevalence of reovirus infection in the northern part of India.Reovirus infection appeared as early as 6 months to 1 year of age. With reovirus types 1 and 2, the maximum incidence of 67 and 48% respectively occurred by the age of 10–20 years, whereas with type 3 infection the maximum incidence (73%) was reached by the age of 25 years. The incidence of reovirus type 2 infection in all the age groups was remarkably low in this series. A drop in the incidence of reovirus type 2 infection was also noticed after the age of 20 years.The difference in geometric mean titre of antibody in different ages against reovirus type 2 was highly significant, suggesting probably that most of the infection occurred by the age of twenty years. The difference in the geometric mean value of the titres of antibody against types 1 and 3 was not significant in different age groups. The levels of antibody against types 1 and 3 in all the age groups were almost the same, suggesting that infection, specially with reovirus type 3, was occurring in all the age groups even beyond 20 years of age.The authors wish to express their sincerest thanks to Dr Leon Rosen, Pacific Research Section, National Institute of Allergy and Infectious Diseases, Honolulu, Hawaii, for the supply of prototype strains of reoviruses, to Drs B. K. Aikat, Director Professor of Pathology, R. N. Chakravarti, Department of Experimental Medicine, O. N. Bhakoo, and Sucheta Thukral, Department of Paediatrics, Post- Graduate Institute of Medical Education and Research, Chadigarh, for their invaluable help and co-operation, to Prof. P. V. K. Iyer, Department of Mathematics, Panjab University, and to Mr H. D. Gupta, Biostatistician, Post-Graduate Institute of Medical Education and Research, Chadigarh for their statistical analysis of the results.The authors gratefully acknowledge the helpful criticism and suggestion of Dr C G. Pandit, Ex-Director, Indian Council of Medical Research, during the preparation of the paper.The authors acknowledge also the technical assistance of Mr Jagmohan Lai Pipat, Mr Gurmeet Singh Khatra, and Mr Amar Singh Saini.This work was partly supported by the Research Grant of the Indian Council of Medical Research sanctioned to one of the authors (S. R. P.).

Oral administration of heat-inactivated lysates of Vibrio cholerae Ogawa L-forms elicited significantly high coproantibody, serum indirect hemagglutinating antibody, and vibriocidal antibody responses in human volunteers, against both homologous and heterologous subtypes of V. cholerae and V. El Tor. Five oral biweekly doses produced an adequate antibody response which persisted for at least 6 weeks after immunization. No untoward side effects were seen.

The name Cunninghamella brunnea spec. nov. has been given to a new phaeosporous merosporangiferous Mucorales isolated from ‘Usar’ soils (pH 8.0-9.0), Lucknow, India. The new species is characterized by the presence of large greyish-brown spores and the absence of vesicles and oil-globules in the hyphae. This species is considered to have evolved as an ecological specialization in response to high temperature and intense solar radiation conditions prevailing in these soils.

Different L-form lysate vaccines of Vibrio cholerae serotypes Ogawa and Inaba and their combination along with ethyl alcohol-precipitated ribonucleic acid (E-RNA) and phenol-extracted RNA (P-RNA) fractions of V. cholerae Ogawa lysates were tested for production of cell-mediated immunity. Both E-RNA and P-RNA fractions induced an increase in leukocyte migration inhibition, macrophage migration inhibition, and macrophage aggregation. They also induced delayed hypersensitivity in rabbits. More consistent results were obtained with the P-RNA fraction.

Chemical Laboratories, Agra College, Agra.-282 002 Manuscript received 12 September 1977, revised 12 September 1979, accepted 26 July 1980 Cu(II)-catalysed oxidation or lactic acid by the peroxodisulphate ion is reported. Kinetic orders in the oxidant, catalyst and reductant concentration have been evaluated. The rate law –[S2O8]2/dt=k[S2O8 ]1.2[Lactic acid]0.4[Cu(II)]0.3 has been interpreted in terms of a most likely mechanism involving oxidation or the Cu(II)-lactate complex by the SO\(^+_4\) and OH radical-ions by parallel reaction pathways.

Oral administration of a single dose of ribonucleic acid-protein fraction of lysates of Vibrio cholerae subtype Ogawa L-forms induced an increase in cell-mediated immunity in rabbits. This was demonstrated by an increase in leukocyte migration inhibition in peripheral blood leukocytes, in macrophages migration inhibition, and in microbicidal activity against Listeria monocytogenes in peritoneal macrophages obtained from orally immunized rabbits. Increased cell-mediated immunity was induced mainly with V. cholerae Ogawa and ribonucleic acid-protein fractions. It appeared in 20 days and persisted for at least 90 days.

Chemistry Division, Indian Lao Research Institute, Namknm, Ranchi-854 010, Manuscript received 20 November 1981, accepted 8 July 1982 Lac resin has been found to contain 10.70% free fatty and 2.7% free aldehydic terpenic acids. The free fatty acids are composed of (i) saturated and unsaturated straight, chain lengths of C14,C15and C18, (ii) 6-ketotetradecanoic, (iii) 6-hydroxy­tetradecanoic (butolic), (iv) 16-hydroxyhexadecanoic, (v) 16-hydroxyhexadec-eis-9- enoic, (vi) \(threo\)-9,10-dihydroxy of C14 and C16 chain lengths and (vii) \(threo\)-9,10,16- trihydroxy hexadecanoic (aleuritic) acids, while the terpenic acids constitute a mixture of jalaric, \(laccijalaric\) and a new aldehydic acid (C15H18O3).