Ultraslow Electron Spin Dynamics in GaAs Quantum Wells Probed by Optically Pumped NMR

Optically pumped nuclear magnetic resonance (OPNMR) measurements were performed in two different electron-doped multiple quantum well samples near the fractional quantum Hall effect ground state nu=1/3. Below 0.5K, the spectra provide evidence that spin-reversed charged excitations of the nu=1/3 ground state are localized over the NMR time scale of ~40 microseconds. Furthermore, by varying NMR pulse parameters, the electron spin temperature (as measured by the Knight shift) could be driven above the lattice temperature, which shows that the value of the electron spin-lattice relaxation time lies between 100 microseconds and 500 milliseconds at nu=1/3.Comment: 6 pages (REVTEX), 6 eps figures embedded in text; published version; minor changes to match published versio

Conservation of energy by utilisation of waste heat direct power reduction in ferro alloy industry

Ferro Alloy Industry is a power intensive industry. Ferro alloys, such as Ferro Manganese, Ferro Silicon, Silico Manganese are manufactured in electric smelting furnace. Due to thermodynamic considerations, production of these Ferro alloys consume large amount of power. With the development of steel industry, requirement of Ferro Alloys as well as power is increasing day-by-day. Hence due consideration can be given in minimising electric power. The object of this paper is to give various directions in which work can be done to achieve saving in power. The paper deals with various factors affecting power consumpt-ion & work areas for improving technology to reduce energy consumption

Utilisation of ore fines by agglomeration with special reference to sintering of manganese ore fines

Agglomeration is required to coagulate the ore fines to the desired size to make them suitable for metallurgical operations. The well known methods of agglomeration are briquetting, pelletisation and Sintering. About 20-30 % of fines are generated during mining operation, handling and screening of ores before they are sized for the smelting furnace. This paper deals with the various process parameters which are determined for the manufacture of Manganese Ore Sinter on a continuous sinter plant of 20 Tons per day capacity

Drug utilization review of anticancer drugs in cancer outpatient department of the Government Medical College, Aurangabad

Background: To study drug utilization of anticancer drugs in cancer outpatient department (OPD) of Government Medical College, Aurangabad.Methods: Five hundred and twelve prescription records were screened and analyzed as per the study parameters from cancer OPD of Government Medical College and Hospital, Aurangabad. Commonly used anticancer drugs were recorded; furthermore, different types of carcinomas were noted.Results: Age group of patients was in between 30 and 70, 267 were females and 245 were male patients. The most common type of carcinoma was carcinoma of the breast (17.9%). Carboplatin was the most commonly used anticancer drug (26.56%). The average number of anticancer drugs received per patient was three.Conclusion: WHO suggested drug utilization studies are needed in every health care setting. For a developing country like India, National Drug Policy and Drugs and Therapeutic Committee are a must

Spectroscopic Evidence for the Localization of Skyrmions near Nu=1 as T->0

Optically pumped nuclear magnetic resonance measurements of Ga-71 spectra were carried out in an n-doped GaAs/Al0.1Ga0.9As multiple quantum well sample near the integer quantum Hall ground state Nu=1. As the temperature is lowered (down to T~0.3 K), a ``tilted plateau'' emerges in the Knight shift data, which is a novel experimental signature of quasiparticle localization. The dependence of the spectra on both T and Nu suggests that the localization is a collective process. The frozen limit spectra appear to rule out a 2D lattice of conventional skyrmions.Comment: 4 pages (REVTEX), 5 eps figures embedded in text, published versio

Observation of a new phase transition between fully and partially polarized quantum Hall states with charge and spin gaps at ν=2/3\nu = 2/3

The average electron spin-polarization $\cal P$ of two-dimensional electron gas confined in $\rm GaAs/GaAlAs$ multiple quantum-wells was measured by nuclear magnetic resonance (NMR) near the fractional quantum Hall state with filling factor $\nu={2/3}$. Above this filling factor (${{2/3}} \leq \nu < 0.85$), a strong depolarization is observed corresponding to two spin flips per additional flux quantum. The most remarkable behavior of the polarization is observed at $\nu ={{2/3}}$, where a quantum phase transition from a partially polarized (${\cal P} \approx {{3/4}}$) to a fully polarized (${\cal P} = 1$) state can be driven by increasing the ratio between the Zeeman and the Coulomb energy above a critical value $\eta_{c} = \frac{\Delta_{Z}}{\Delta_{C}} = 0.0185$.Comment: 4 pages including 4 figure

NMR Determination of 2D Electron Spin Polarization at ν=1/2\nu=1/2

Using a `standard' NMR spin-echo technique we determined the spin polarization of two-dimensional electrons, confined to GaAs quantum wells, from the hyperfine shift of Ga nuclei in the wells. Concentrating on the temperature and magnetic field dependencies of spin polarization at Landau level filling factor $\nu =1/2$, we find that the results are described well by a simple model of non-interacting composite fermions, although some inconsistencies remain when the two-dimensional electron system is tilted in the magnetic field.Comment: 4 pages (REVTEX) AND 4 figures (PS

Optically Pumped NMR Measurements of the Electron Spin Polarization in GaAs Quantum Wells near Landau Level Filling Factor nu=1/3

The Knight shift of Ga-71 nuclei is measured in two different electron-doped multiple quantum well samples using optically pumped NMR. These data are the first direct measurements of the electron spin polarization, P(nu,T)=/max, near nu=1/3. The P(T) data at nu=1/3 probe the neutral spin-flip excitations of a fractional quantum Hall ferromagnet. In addition, the saturated P(nu) drops on either side of nu=1/3, even in a Btot=12 Tesla field. The observed depolarization is quite small, consistent with an average of about 0.1 spin-flips per quasihole (or quasiparticle), a value which does not appear to be explicable by the current theoretical understanding of the FQHE near nu=1/3.Comment: 4 pages (REVTEX), 5 eps figures embedded in text; minor changes, published versio

Induction of direct somatic embryogenesis and plant regeneration from mature cotyledon explants of Arachis hypogea L

A plant regeneration method via direct somatic embryogenesis was achieved in cotyledon explants derived from mature, dry seeds of Arachis hypogaea L. According to histological observations, somatic embryogenesis was induced directly without any intervening callus on MS medium supplemented with different concentrations of BAP along with 2.68 &#956;M NAA after 4 weeks of culture. The incidence of somatic embryogenesis was greater at the distal end of the cotyledon than the remaining portion. The range of embryogenesis frequency was 10.7 to 80.2 %, depending on the BAP concentration in combination with NAA. The best response was observed on MS medium containing 22.19 &#956;M BAP along with 2.68 &#956;M NAA. The embryos matured and germinated on fresh medium with or without growth regulators. A large percentage of somatic embryos developed into normal plants producing viable seeds. Some embryos produced flower buds on the germination medium

Brain microenvironment-driven resistance to immune and targeted therapies in acral melanoma.

BACKGROUND: Combination treatments targeting the MEK-ERK pathway and checkpoint inhibitors have improved overall survival in melanoma. Resistance to treatment especially in the brain remains challenging, and rare disease subtypes such as acral melanoma are not typically included in trials. Here we present analyses from longitudinal sampling of a patient with metastatic acral melanoma that became resistant to successive immune and targeted therapies. METHODS: We performed whole-exome sequencing and RNA sequencing on an acral melanoma that progressed on successive immune (nivolumab) and targeted (dabrafenib) therapy in the brain to identify resistance mechanisms. In addition, we performed growth inhibition assays, reverse phase protein arrays and immunoblotting on patient-derived cell lines using dabrafenib in the presence or absence of cerebrospinal fluid (CSF) in vitro. Patient-derived xenografts were also developed to analyse response to dabrafenib. RESULTS: Immune escape following checkpoint blockade was not due to loss of tumour cell recognition by the immune system or low neoantigen burden, but was associated with distinct changes in the microenvironment. Similarly, resistance to targeted therapy was not associated with acquired mutations but upregulation of the AKT/phospho-inositide 3-kinase pathway in the presence of CSF. CONCLUSION: Heterogeneous tumour interactions within the brain microenvironment enable progression on immune and targeted therapies and should be targeted in salvage treatments