Ideal Spin Filters: Theoretical Study of Electron Transmission Through Ordered and Disordered Interfaces Between Ferromagnetic Metals and Semiconductors

It is predicted that certain atomically ordered interfaces between some ferromagnetic metals (F) and semiconductors (S) should act as ideal spin filters that transmit electrons only from the majority spin bands or only from the minority spin bands of the F to the S at the Fermi energy, even for F with both majority and minority bands at the Fermi level. Criteria for determining which combinations of F, S and interface should be ideal spin filters are formulated. The criteria depend only on the bulk band structures of the S and F and on the translational symmetries of the S, F and interface. Several examples of systems that meet these criteria to a high degree of precision are identified. Disordered interfaces between F and S are also studied and it is found that intermixing between the S and F can result in interfaces with spin anti-filtering properties, the transmitted electrons being much less spin polarized than those in the ferromagnetic metal at the Fermi energy. A patent application based on this work has been commenced by Simon Fraser University.Comment: RevTeX, 12 pages, 5 figure

Screening for Diabetes Mellitus in Patients Diagnosed with Pulmonary Tuberculosis

Background: The epidemic of diabetes mellitus (DM) poses a threat for global tuberculosis (TB) control. Objective: This study attempts to assess the value of screening for diabetes in patients with pulmonary tuberculosis and reviews the disease burden, clinical and radiographic manifestations, rates of sputum smear positivity and time to conversion, treatment outcomes and fatality rates, in the local setting. Methods: This is a prospective observational cohort study involving adults diagnosed with pulmonary tuberculosis at the PTSI TB DOTS out-patient clinic, r e g a r d l e s s o f s p u t u m -s m e a r s t a t u s , f r o m J u l y 2011-November 2012. A diabetes screening tool was used and patients were screened for presence of DM. Treatment outcomes were also determined. Results: Of the 38 patients enrolled, seven (18.4%, 95% confidence interval 7.7-34.3) were diagnosed with DM. This is higher than the estimated 12.9% in 2010 and 14.4% projected estimate in 2030 in our country by a report of WHO as well as in reported prevalence of DM among patients with PTB in large studies done in China (12.4%) and India (13%). There was no significant difference noted in the basic profile, clinical and radiographic presentation, sputum conversion and treatment outcomes among patients with DM and without DM who were being treated for PTB. Conclusion: This study demonstrates the value and feasibility of screening for DM among patients with PTB. Although the findings of this study are consistent with most of previous similar studies, the estimate on the true prevalence of DM may not be very accurate because of the small sample size. Hence, a multi-center study with a larger sample size must be conducted to more accurately measure the true prevalence of DM among patients with TB and to determine associations of various clinical and radiographic presentations and clinical outcomes. Keywords: diabetes mellitus, pulmonary tuberculosis, screening Abstract Introductio

Generating Neutrino Mass in the 331 Model

A mechanism for generating small tree-level Majorana mass for neutrinos is implemented in the 331 Model. No additional fermions or scalars need to be added, and no mass scale greater than a few TeV is invoked.Comment: LaTex, 7 pages, no figures. Revised version to appear in Phys. Rev.

Nicotine coregulates multiple pathways involved in protein modification/degradation in rat brain

Previously, we used cDNA microarrays to demonstrate that the phosphatidylinositol and MAP kinase signaling pathways are regulated by nicotine in different rat brain regions. In the present report, we show that, after exposure to nicotine for 14 days, ubiquitin, ubiquitin-conjugating enzymes, 20S and 19S proteasomal subunits, and chaperonin-containing TCP-1 protein (CCT) complex members are upregulated in rat prefrontal cortex (PFC) while being downregulated in the medial basal hypothalamus (MBH). In particular, relative to saline controls, ubiquitins B and C were upregulated by 33% and 47% (P<0.01), respectively, in the PFC. The proteasome beta subunit 1 (PSMB1) and 26S ATPase 3 (PSMC3) genes were upregulated in the PFC by 95% and 119% (P<0.001), respectively. In addition to the protein degradation pathway of the ubiquitin-proteasome complexes, we observed in the PFC an increase in the expression of small, ubiquitin-related modifiers (SUMO) 1 and 2 by 80% and 33%, respectively (P<0.001), and in 3 of 6 CCT subunits by up to 150% (P<0.0001). To a lesser extent, a change in the opposite direction was obtained in the expression of the same gene families in the MBH. Quantitative real-time RT-PCR was used to validate the microarray results obtained with some representative genes involved in these pathways. Taken together, our results suggest that, in response to systemic nicotine administration, the ubiquitin-proteasome, SUMO, and chaperonin complexes provide an intricate control mechanism to maintain cellular homeostasis, possibly by regulating the composition and signaling of target neurons in a region-specific manner. © 2004 Elsevier B.V. All rights reserved

Mixed symmetry superconductivity in two-dimensional Fermi liquids

We consider a 2D isotropic Fermi liquid with attraction in both $s$ and $d$ channels and examine the possibility of a superconducting state with mixed $s$ and $d$ symmetry of the gap function. We show that both in the weak coupling limit and at strong coupling, a mixed $s+id$ symmetry state is realized in a certain range of interaction. Phase transitions between the mixed and the pure symmetry states are second order. We also show that there is no stable mixed $s+d$ symmetry state at any coupling.Comment: 3 figures attached in uuencoded gzipped file

Statistical Modelling Optimisation of Cellulase Enzyme Immobilisation on Functionalised Multi-Walled Carbon Nanotubes for Empty Fruit Bunches Degradation

Abstract: Cellulase obtained from the fermentation of sewage treatment plant sludge (STP) by Trichoderma-reesei RUT C-30 was covalently immobilised on functionalised multi-wall carbon nanotubes. Statistical optimisation using the Plackett-Burman design method was implemented to identify parameters with significant effects on the process of immobilisation. The results obtained from this Plackett-Burman design show that three parameters have a significant effect on immobilisation: pH, temperature, and N-ethyl-N-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC) concentration. Based on our Plackett-Burman design results, these parameters were further optimised using a face-centred central composite design. The resulting optimum conditions for cellulase immobilisation, as determined by face-centred central composite design, were pH 4.5, 30°C, and 1 mL of 10mg/mL EDC. The amount of immobilised cellulase was approximately 98% using these optimum conditions. The resulting MWCNT-cellulase composite was further characterized by FTIR and SEM. The FTIR spectrum of MWCNT-cellulase composite showed an amide group peak (O = C-NH) corresponding to cellulase enzyme, which confirms that immobilisation took place

Quantized Thermal Transport in the Fractional Quantum Hall Effect

We analyze thermal transport in the fractional quantum Hall effect (FQHE), employing a Luttinger liquid model of edge states. Impurity mediated inter-channel scattering events are incorporated in a hydrodynamic description of heat and charge transport. The thermal Hall conductance, $K_H$, is shown to provide a new and universal characterization of the FQHE state, and reveals non-trivial information about the edge structure. The Lorenz ratio between thermal and electrical Hall conductances {\it violates} the free-electron Wiedemann-Franz law, and for some fractional states is predicted to be {\it negative}. We argue that thermal transport may provide a unique way to detect the presence of the elusive upstream propagating modes, predicted for fractions such as $\nu=2/3$ and $\nu=3/5$.Comment: 6 pages REVTeX, 2 postscript figures (uuencoded and compressed