Low temperature saturation of phase coherence length in topological insulators

Implementing topological insulators as elementary units in quantum technologies requires a comprehensive understanding of the dephasing mechanisms governing the surface carriers in these materials, which impose a practical limit to the applicability of these materials in such technologies requiring phase coherent transport. To investigate this, we have performed magneto-resistance (MR) and conductance fluctuations\ (CF) measurements in both exfoliated and molecular beam epitaxy grown samples. The phase breaking length ($l_{\phi}$) obtained from MR shows a saturation below sample dependent characteristic temperatures, consistent with that obtained from CF measurements. We have systematically eliminated several factors that may lead to such behavior of $l_{\phi}$ in the context of TIs, such as finite size effect, thermalization, spin-orbit coupling length, spin-flip scattering, and surface-bulk coupling. Our work indicates the need to identify an alternative source of dephasing that dominates at low $T$ in topological insulators, causing saturation in the phase breaking length and time

Increased toll-like receptor-2 expression on nonclassic CD16⁺monocytes from patients with inflammatory stage of eales' disease

Purpose.: To identify the distribution, differential Toll-like receptor (TLR) expression, and functional contribution of monocyte subpopulations in the inflammatory stage of Eales' disease (ED). Methods.: Peripheral blood mononuclear cells were isolated from nine patients during the inflammatory stage of ED and nine age- and sex-matched healthy controls. The expression of CD14, CD16, TLR-2, and TLR-4 on monocytes was measured by flow cytometry. The CD14+, CD16−, and CD16+ monocyte populations were sorted on the basis of magnetic-activated cell-sorting methodology, and levels of cytokines were measured by ELISA. Results.: In ED patients, the number of circulating monocytes was significantly expanded compared with that in controls (P = 0.01), with a marked increase in the nonclassic CD16+ subset, which showed an activated phenotype in patients that correlated with levels of serum proinflammatory cytokines and clinical progression. A higher expression of cell surface TLR-2 (P = 0.02), but not TLR-4, was found in monocytes of patients with ED. Furthermore, TLR-2 was expressed at higher levels on CD16+ monocytes than on CD16− monocytes in patients, whereas no significant variation was found in TLR-4 expression on different monocyte subsets. Peptidoglycan-induced TNF-α expression correlated with TLR-2 expression in monocytes isolated from controls (r = 0.85, P = 0.0061), but not in monocytes isolated from ED patients (r = 0.553, P = 0.1328). Conclusions.: These results indicate that in the pathogenesis of ED, TLR activation and increased numbers of nonclassic CD16+ monocytes are crucial regulators, along with the secretion of proinflammatory cytokines that perpetuate the inflammatory process in the retina

Ratio of neutrophilic CD64 and monocytic HLA-DR: a novel parameter in diagnosis and prognostication of neonatal sepsis

Objective: Approaches to monitoring of sepsis have traditionally relied upon the pro-inflammatory component of the sepsis response. This study evaluated the diagnostic and prognostic potential of the ratio of neutrophilic CD64 (nCD64) and monocytic HLA-DR (mHLA-DR) median fluorescence index in monitoring of neonatal sepsis. Methods: Blood from 100 neonates suspected of sepsis and 29 healthy controls was collected on clinical suspicion of sepsis, and the expression of nCD64, mHLA-DR was evaluated by Flow Cytometry; thereby, a derived parameter “Sepsis index,” SI = nCD64/mHLA-DR × 100 was estimated. Results: At day 1, sensitivity and specificity to detect sepsis using nCD64 was 73.01% and 89.18%, respectively, while for SI it was 73.01% and 72.22%, respectively. On Kaplan-Meier analysis, neonates with SI > cut-off showed a higher 30 day-mortality than those with low SI (P = 0.096). On multivariate analysis, the factor associated with mortality in our cohort was Apgar score ≤3, while SI showed a trend toward significance. Conclusions: At day1, nCD64 is useful for the diagnosis of neonatal sepsis whereas mHLA-DR is beneficial for monitoring patients at a later time point. The SI is a marker of moderate diagnostic sensitivity and supplements the current arsenal of laboratory investigations to detect neonatal sepsis. As a marker of prognosis, a high SI shows a trend towards greater mortality

Berberine Chloride Mediates Its Anti-Leishmanial Activity via Differential Regulation of the Mitogen Activated Protein Kinase Pathway in Macrophages

BACKGROUND: A complex interplay between Leishmania and macrophages influences parasite survival and necessitates disruption of signaling molecules, eventually resulting in impairment of macrophage function. In this study, we demonstrate the immunomodulatory activity of Berberine chloride in Leishmania infected macrophages. PRINCIPAL FINDINGS: The IC(50) of Berberine chloride, a quaternary isoquinoline alkaloid was tested in an amastigote macrophage model and its safety index measured by a cell viability assay. It eliminated intracellular amastigotes, the IC(50) being 2.8 fold lower than its IC(50) in promastigotes (7.10 µM vs. 2.54 µM) and showed a safety index >16. Levels of intracellular and extracellular nitric oxide (NO) as measured by flow cytometry and Griess assay respectively showed that Berberine chloride in Leishmania infected macrophages increased production of NO. Measurement of the mRNA expression of iNOS, IL-12 and IL-10 by RT-PCR along with levels of IL-12p40 and IL-10 by ELISA showed that in infected macrophages, Berberine chloride enhanced expression of iNOS and IL-12p40, concomitant with a downregulation of IL-10. The phosphorylation status of extracellular signal related kinase (ERK1/2) and p38 mitogen activated protein kinase (p38 MAPK) was studied by western blotting. In infected macrophages, Berberine chloride caused a time dependent activation of p38 MAPK along with deactivation of ERK1/2; addition of a p38 MAPK inhibitor SB203580 inhibited the increased generation of NO and IL-12p40 by Berberine chloride as also prevented its decrease of IL-10. CONCLUSIONS: Berberine chloride modulated macrophage effector responses via the mitogen activated protein kinase (MAPK) pathway, highlighting the importance of MAPKs as an antiparasite target

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Plant derived therapeutics for the treatment of Leishmaniasis

Diseases caused by insect borne trypanosomatid parasites are significant, yet remain a neglected public health problem. Leishmania, a unicellular protozoan parasite is the causative organism of Leishmaniasis and is transmitted by female phlebotamine sandflies affecting millions of people worldwide. In the wake of resistance to pentavalent antimonial drugs, new therapeutic alternatives are desirable. The plant kingdom has in the past provided several affordable compounds and this review aims to provide an overview of the current status of available leishmanicidal plant derived compounds that are effective singly or in combination with conventional anti-leishmanial drugs, yet are non toxic to mammalian host cells. Furthermore, delineation of the contributory biochemical mechanisms involved in mediating their effect would help develop new chemotherapeutic approaches

In situ carbon deposition in polyetherimide/SAPO-34 mixed matrix membrane for efficient CO2/CH4 separation

A simple method of pore modification complied with defect removal polymer zeolite mixed matrix membrane was developed by in situ carbon (C) deposition. The C deposition was achieved by the controlled decomposition of polymer matrix by heat treatment. In this study, polyetherimide/silicoaluminophosphate-34 mixed matrix membrane (MMM) was fabricated on clay-alumina support tube, followed by carbonization of the polymer matrix for gas separation application. MMM without heat treatment were also synthesized for comparison by conventional method. The membranes were characterized by X-ray diffraction, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy. Due to carbonization, in situ C nanoparticles were deposited in to the interfacial pores, and filler particles were oriented in preferable direction. The presence of CO, CN, and graphitic carbon in the matrix, may be an indication of partial carbonization and restoration of adherence of polymer with substrate. The separation factor for CO2/CH4 achieved 39.15 with a permeance value of 23.01 x 10(-8)mol/(m(2)sPa) for CO2 at 30 degrees C and 200 kPa feed pressure. For the first time, this work shows an improvement toward permeability of MMM by simple carbonization of polymer matrix with commendable values as compare to the reported literature. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45508

Development of LTA zeolite membrane from clay by sonication assisted method at room temperature for H-2-CO2 and CO2-CH4 separation

In this work, sodium aluminosilicate zeolite powder and membranes were synthesized by ultrasonic irradiation at room temperature using montmorillonite clay as precursor material. For comparison, same zeolite powder and membranes were synthesized at 100 degrees C also. The synthesized zeolites were characterized by X-ray diffraction (XRD), infrared (IR) spectral analysis, and field-emission scanning electron microscopy (FESEM). XRD and IR results showed that phase pure mainly LTA phase was formed after 15 days of aging at room temperature. By using the zeolite powders as seeds, membranes were synthesized on clay alumina support tubes at room temperature and also at 100 degrees C. In both the cases membranes were formed on support surface. The membrane thickness was found to be 15 mu m. The performances of the membranes were evaluated by single gas as well as mixture gas permeation measurement for H-2-CO2 and CO2-CH4 respectively. The H-2-CO2 and CO2-CH4 separation selectivity for the mixture gas of the membrane was found to 16.2 and 20.9 at room temperature respectively. To the best of our knowledge, there is no report of synthesis of zeolite membrane at room temperature using clay as raw materials. For the first time we have reported the synthesis of alumino-silicate zeolite membrane on clay alumina support surface using clay as starting material by sonochemical method at room temperature