Search Results - (Author, Cooperation:A. Chakraborty)

2018-07-27

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Cell Biology, Molecular Biology, Online Only

2018-08-01

American Physical Society (APS)

0556-2813

1089-490X

Physics

Nuclear Structure

2018-10-04

Genetics Society of America (GSA)

2160-1836

Biology

2011-01-05

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Acetylation ; Animals ; Cell Line, Tumor ; Cell Proliferation ; Colonic Neoplasms/metabolism/pathology ; DNA-Binding Proteins/*antagonists & inhibitors/deficiency/*metabolism ; Gene Expression Regulation, Neoplastic ; Histones/metabolism ; Intestines/cytology ; JNK Mitogen-Activated Protein Kinases/metabolism ; Mi-2 Nucleosome Remodeling and Deacetylase Complex/*antagonists & ; inhibitors/chemistry/*metabolism ; Mice ; Phosphorylation ; Promoter Regions, Genetic/genetics ; Protein Binding ; Proto-Oncogene Proteins c-jun/*chemistry/*metabolism ; Receptors, G-Protein-Coupled/genetics ; Stem Cells/cytology ; Transcription Factors/*antagonists & inhibitors/deficiency/*metabolism

2018-07-06

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

2012-08-04

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

DNA Polymerase III/*chemistry/drug effects ; Fluorescence Resonance Energy Transfer/methods ; *Gene Expression Regulation, Bacterial ; Protein Conformation ; *Transcription, Genetic

2018-09-07

American Physical Society (APS)

0556-2813

1089-490X

Physics

Nuclear Structure

2018-03-06

Oxford University Press

1367-4803

1460-2059

Biology

Computer Science

Medicine

2018-07-14

Institute of Physics (IOP)

1757-8981

1757-899X

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

2018-12-15

The American Association for Cancer Research (AACR)

1078-0432

1557-3265

Medicine

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A washer plasma gun for alkali-metal plasma is developed. This gun is suitable as a source for experiments on alkali-metal plasmas, plasma diagnostics, and in various applications such as ion-beam sputter deposition. The gun uses an injector of alkali-metal vapor based on the principles of laser ablation. Acceleration is performed by a large electrical field provided across eight washers. The gun is compact, stable, and easy to fabricate and use. The gun produces a neutral Li0 beam current of 1 A/cm2 and a Li+ ion current of 50 A/cm2 at its exit at 10 kV of capacitor bank voltage. With this intensity, it is possible to produce beams of neutral Li0 atoms of density 6×109 cm−3 and Li+ ions of density ∼1011 cm−3 at 1 m from the gun, moving with a velocity of ∼107 cm/s.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

FeN materials exhibiting high moment, low coercivity and small magnetostriction have previously been reported. Zr has been known to reduce the magnetostriction in other Fe alloys. The criteria for an ideal recording head pole material as well as shields for magnetroresistive sensors include high moment, low coercivity, high permeability, and zero magnetostriction. We present here the properties of half micrometer thick rf sputtered FeZrN films on glass coupons. The films were deposited at a pressure of 3 mTorr using a Perkin–Elmer sputtering system. The target was composed of Fe with Zr chips covering approximately 2% of the surface area. The properties were measured as a function of the N2 partial pressure. The saturation magnetization of the as-sputtered films was approximately 20 kG. The easy axis and the hard axis coercivities show minima at approximately 7%–10% N2 partial pressure of approximately 1.8 and 0.6 G, respectively. The magnetic anisotropy is approximately 5 G yielding a dc permeability of approximately 4000 along the hard axis. X-ray data reveal a systematic change in the ratio of α-Fe and γ-Fe4N; the amount of the γ-Fe4N phase increases with increasing N2 flow rate. The magnetostriction increases with increasing N2 content crossing zero at approximately 6%. The grain size as probed by atomic force microscopy is an increasing function of the N2 partial pressure, from a few nm for a N2 partial pressure of 5% to as large as 50 nm for a N2 partial pressure of 15%. © 1996 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

FeN materials exhibiting high moment, low coercivity and small magnetostriction have previously been reported. Zr has been known to reduce the magnetostriction in other Fe alloys. The criteria for an ideal recording head pole material as well as shields for magnetoresistive sensors include high moment, low coercivity, high permeability, and zero magnetostriction. We present here the properties of 0.3 μm thick rf sputtered FeZrN films measured as a function of the N2 partial pressure. The films were deposited at a pressure of 3 mT using a Perkin Elmer sputtering system. The target was composed of Fe with Zr chips covering approximately 2% of the surface area. The easy axis and hard axis coercivities show minima of 1.8 and 0.6 Oe, respectively, at 7–10 % N2 partial pressure with a saturation magnetization of about 18 kG. The magnetic anisotropy field is approximately 5 Oe yielding a dc permeability of approximately 4000 along the hard axis. X-ray data reveal a systematic change in the ratio of α–Fe and γ–Fe4 N; the amount of the γ–Fe4N phase increasing with increasing N2 partial pressure. The magnetostriction increases with increasing N2 content crossing zero at approximately 6%. The grain size, as probed by atomic force microscopy, is an increasing function of the N2 partial pressure; from a few nm for N2 partial pressures of 5% to being as large as 50 nm for a partial pressure of 15%. The surface roughness is about 1 nm. © 1996 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Ferromagnetism has only recently been observed in molecular materials. We present here a summary of the ferromagnetic phenomena observed in the molecular charge transfer salt, decamethylferrocenium tetracyanoethanide (DMeFc)(TCNE), and related compounds. A spontaneous magnetization is observed in this material for T〈4.8 K, with a saturation moment in agreement with alignment of individual spins localized on the DMeFc+⋅ and TCNE−⋅ ions. A comparison of these results with analogous charge transfer salts is presented. Models for the magnetic interaction in the charge transfer salts and the preparation of other molecular and/or polymeric materials with ferromagnetic exchange are presented.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Monte Carlo simulation based on Widom's test particle method is used to study the behavior of dilute ionic solutes in a quenched disordered medium with ionized obstacles. The structure of the medium is assumed to correspond to that of an ionic fluid equilibrated at certain prequenching temperature Tq and permittivity εq different from the corresponding values at the conditions of observation. The correlations among solute ions display qualitative differences from those observed in annealed systems. The ions of equal sign are attracted to domains of the disordered material characterized by charge opposite to that of the ions. The attraction of ions of the same sign to the same domains results in an apparent attractive contribution to the disorder-averaged interionic potential. At distances sufficiently exceeding the screening length pertaining to the ionized obstacles at the prequenching conditions, the disorder-induced term prevails over the direct Coulombic repulsion and a net attraction is observed. A similar mechanism leads to a long-ranged repulsion between oppositely charged ions. These findings are in agreement with earlier calculations of the disorder-averaged ion–ion potentials based on the asymptotic Debye–Hückel description of the disordered medium. The simulations are also used to estimate the effects of the medium on thermodynamic properties of the embedded ionic solute. The energies and activity coefficients are found to decrease with the product of the prequenching temperature and permittivity, a phenomenon explained in terms of the increase of the potential fluctuations in the disordered medium with growing εqTq. In spite of its global electroneutrality, the quenched medium displays a strong selectivity with respect to the valency of the solute, the tendency towards absorption increasing with the charge of the ions. The selectivity rapidly increases with increasing value of the characteristic product of the prequenching temperature and the permittivity εqTq. © 1996 American Institute of Physics.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

We use Monte Carlo simulations to study the thermodynamics and structural behavior of random heteropolymers immersed in a disordered medium. Simulation results pertain to isolated heteropolymer chains with renormalized intrachain interactions determined by analytic averaging over the realizations of the external medium. Two situations are considered. In the first scenario, the random heteropolymer is such that segments of different type have a propensity to segregate, while in the second situation different types of segments prefer to be adjacent to each other. Polymer configurations are generated by the ensemble-growth Monte Carlo method wherein the slow-down effects that typically hinder dynamic Monte Carlo simulations of compact polymer states with strong interactions are alleviated. Our simulations show that for the case where the bare heteropolymer prefers to form segregated patterns, below a certain temperature, the random heteropolymer "folds" into a few dominant conformations with a segregated pattern of contacts. In the case where the bare heteropolymer favors mixing of different types of segments we find richer behavior. Here, our simulations show the existence of two frozen phases separated by a reentrant phase as temperature (or strength of the external disorder) is scanned. The heteropolymers in the two frozen phases are "folded" in different patterns (high T, mixed pattern; low T, segregated pattern). The physical reasons for these phenomena are elucidated based on our simulation results for structural features of the polymer. The results agree remarkably well with a simple mean-field theory, a fact that may be of some general consequence. Specific experiments are suggested to test the phenomena that we predict. © 1997 American Institute of Physics.

Electronic Resource

1365-2036

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Background:  Active paediatric Crohn's disease is associated with nutritional deficiencies and altered nutrient intake. The availability of essential fatty acids (linoleic and α-linolenic acids) or their derivatives (arachidonic and eicosapentaenoic acids) may alter in plasma and cell membrane phospholipid in protein-energy malnutrition in children and in Crohn's disease in adults.Aim:  To investigate the relationship of fatty acid phospholipid profiles with disease activity and nutritional status in paediatric Crohn's disease.Methods:  The fatty acid (proportionate) composition of plasma and erythrocyte phosphatidylcholine was determined in 30 patients (10.3–17.0 years) stratified into active and quiescent Crohn's disease (paediatric Crohn's disease activity index) and high and low body mass (body mass index centile).Results:  In plasma phosphatidylcholine, active disease activity was associated with a lower level of α-linolenic acid compared with that in quiescent disease (P 〈 0.05). A body mass index below the 50th centile was associated with active Crohn's disease, low linoleic and α-linolenic acids and high arachidonic acid (P 〈 0.05) in plasma phosphatidylcholine, and low α-linolenic acid in erythrocyte phosphatidylcholine. These findings could not be explained through differences in habitual dietary fat intake.Conclusion:  In paediatric Crohn's disease, a low body mass index centile and high disease activity are associated with altered profiles of essential fatty acids and their derivatives, which may reflect altered metabolic demand.

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource