Fire and Smoke Remote Sensing and Modeling Uncertainties: Case Studies in Northern Sub‐Saharan Africa

Significant uncertainties are incurred in deriving various quantities related to biomass burning from satellite measurements at different scales, and, in general, the coarser the resolution of observation the larger the uncertainty. WRF‐Chem model simulations of smoke over the northern sub‐Saharan African (NSSA) region for January–February 2010, using fire energetics and emissions research version 1.0 (FEERv1) aerosol emissions derived from MODIS measurements of fire radiative power (FRP) and aerosol optical depth (AOD), resulted in a severe model underestimation of AOD compared with satellite retrievals. Such uncertainties are attributable to three major factors: limitations in the spatial and temporal resolutions of the satellite observations used to quantify emissions, modeling parameters and assumptions, and the unique geographic characteristics of NSSA. It is recommended that field campaigns involving synergistic coordination of ground‐based, airborne, and satellite measurements with modeling be conducted in major and complex biomass burning regions such as the NSSA, and that significant improvements in the spatial and temporal resolutions of observation systems needed to reduce uncertainties in biomass burning characterization be seriously considered in future satellite missions

Fire and Smoke Remote Sensing and Modeling Uncertainties: Case Studies in Northern Sub‐Saharan Africa

Significant uncertainties are incurred in deriving various quantities related to biomass burning from satellite measurements at different scales, and, in general, the coarser the resolution of observation the larger the uncertainty. WRF‐Chem model simulations of smoke over the northern sub‐Saharan African (NSSA) region for January–February 2010, using fire energetics and emissions research version 1.0 (FEERv1) aerosol emissions derived from MODIS measurements of fire radiative power (FRP) and aerosol optical depth (AOD), resulted in a severe model underestimation of AOD compared with satellite retrievals. Such uncertainties are attributable to three major factors: limitations in the spatial and temporal resolutions of the satellite observations used to quantify emissions, modeling parameters and assumptions, and the unique geographic characteristics of NSSA. It is recommended that field campaigns involving synergistic coordination of ground‐based, airborne, and satellite measurements with modeling be conducted in major and complex biomass burning regions such as the NSSA, and that significant improvements in the spatial and temporal resolutions of observation systems needed to reduce uncertainties in biomass burning characterization be seriously considered in future satellite missions

Magneto-transport and electronic structures in MoSi2_2 bulks and thin films with different orientations

We report a comprehensive study of magneto-transport properties in MoSi$_2$ bulk and thin films. Textured MoSi$_2$ thin films of around 70 nm were deposited on silicon substrates with different orientations. Giant magnetoresistance of 1000% was observed in sintered bulk samples while MoSi$_2$ single crystals exhibit a magnetoresistance (MR) value of 800% at low temperatures. At the low temperatures, the MR of the textured thin films show weak anti-localization behaviour owing to the spin orbit coupling effects. Our first principle calculation show the presence of surface states in this material. The resistivity of all the MoSi$_2$ thin films is significantly low and nearly independent of the temperature, which is important for electronic devices

Nitrate formation from heterogeneous uptake of dinitrogen pentoxide during a severe winter haze in southern China

Nitrate (NO3-) has become a major component of fine particulate matter (PM2.5) during hazy days in China. However, the role of the heterogeneous reactions of dinitrogen pentoxide (N2O5) in nitrate formation is not well constrained. In January 2017, a severe haze event occurred in the Pearl River Delta (PRD) of southern China during which high levels of PM2.5 (∼400&thinsp;µg&thinsp;m−3) and O3 (∼160&thinsp;ppbv) were observed at a semi-rural site (Heshan) in the western PRD. Nitrate concentrations reached 108&thinsp;µg&thinsp;m−3 (1&thinsp;h time resolution), and the contribution of nitrate to PM2.5 was nearly 40&thinsp;%. Concurrent increases in NO3- and ClNO2 (with a maximum value of 8.3&thinsp;ppbv at a 1&thinsp;min time resolution) were observed in the first several hours after sunset, indicating an intense N2O5 heterogeneous uptake by aerosols. The formation potential of NO3- via N2O5 heterogeneous reactions was estimated to be between 29.0 and 77.3&thinsp;µg&thinsp;m−3 in the early hours (2 to 6&thinsp;h) after sunset based on the measurement data, which could completely explain the measured increase in the NO3- concentration during the same time period. Daytime production of nitric acid from the gas-phase reaction of OH+NO2 was calculated with a chemical box model built using the Master Chemical Mechanism (MCM v3.3.1) and constrained by the measurement data. The integrated nocturnal nitrate formed via N2O5 chemistry was comparable to or even higher than the nitric acid formed during the day. This study confirms that N2O5 heterogeneous chemistry was a significant source of aerosol nitrate during hazy days in southern China.</p

The pharmacological regulation of cellular mitophagy

Small molecules are pharmacological tools of considerable value for dissecting complex biological processes and identifying potential therapeutic interventions. Recently, the cellular quality-control process of mitophagy has attracted considerable research interest; however, the limited availability of suitable chemical probes has restricted our understanding of the molecular mechanisms involved. Current approaches to initiate mitophagy include acute dissipation of the mitochondrial membrane potential (ΔΨm) by mitochondrial uncouplers (for example, FCCP/CCCP) and the use of antimycin A and oligomycin to impair respiration. Both approaches impair mitochondrial homeostasis and therefore limit the scope for dissection of subtle, bioenergy-related regulatory phenomena. Recently, novel mitophagy activators acting independently of the respiration collapse have been reported, offering new opportunities to understand the process and potential for therapeutic exploitation. We have summarized the current status of mitophagy modulators and analyzed the available chemical tools, commenting on their advantages, limitations and current applications

The Role of Cytokines which Signal through the Common γ Chain Cytokine Receptor in the Reversal of HIV Specific CD4(+) and CD8(+) T Cell Anergy

BACKGROUND: HIV specific T cells are putatively anergic in vivo. IL-2, a member of a class of cytokines that binds to receptors containing the common gamma chain (γc) has been shown to reverse anergy. We examined the role of γc cytokines in reversing HIV specific T cell anergy. METHODS: PBMC from untreated HIV-infected individuals were briefly exposed to a panel of γc cytokines, and frequencies of gag specific T cells were enumerated by intracellular IFN-γ flow cytometry. RESULTS: Of the γc cytokines, brief exposure to IL-2, IL-15, or combined IL-15/IL-7 significantly enhanced (range 2–7 fold) the CD4(+) and CD8(+) T cell IFN-γ responses to HIV gag, with IL-15 giving the greatest enhancement. The effects of cytokines were not due to enhanced proliferation of pre-existing antigen specific cells, but were due to a combination of enhanced cytokine production from antigen specific T cells plus activation of non-epitope specific T cells. CONCLUSIONS: These observations support the notion that a significant number of HIV specific T cells are circulating in an anergic state. IL-2, IL-7 and particularly IL-15 as an immune modulator to reverse HIV-1 specific T cell anergy should be investigated, with the caveat that non-specific activation of T cells may also be induced

Field evaluation of an immunochromatographic test for diagnosis of cystic and alveolar echinococcosis

Background: The larval stages of the tapeworms Echinocoocus granulosus and Echinococcus multilocularis are the causative agents of human cystic echinococcosis (CE) and human alveolar echinococcosis (AE), respectively. Both CE and AE are chronic diseases characterised by long asymptomatic periods of many years. However, early diagnosis of the disease is important if treatment and management of echinococcosis patients are to be successful. Methods: A previously developed rapid diagnostic test (RDT) for the differential detection of CE and AE was evaluated under field conditions with finger prick blood samples taken from 1502 people living in the Ganzi Tibetan Autonomous Prefecture, China, a region with a high prevalence for both forms of human echinococcosis. The results were compared with simultaneously obtained abdominal ultrasonographic scans of the individuals. Results: Using the ultrasonography as the gold standard, sensitivity and specificity, and the diagnostic accuracy of the RDT were determined to be greater than 94% for both CE and AE. For CE cases, high detection rates (95.6–98.8%) were found with patients having active cysts while lower detection rates (40.0–68.8%) were obtained with patients having transient or inactive cysts. In contrast, detection rates in AE patients were independent of the lesion type. The positive likelihood ratio of the RDT for CE and AE was greater than 20 and thus fairly high, indicating that a patient with a positive test result has a high probability of having echinococcosis. Conclusions: The results suggest that our previously developed RDT is suitable as a screening tool for the early detection of human echinococcosis in endemic areas

A novel tumor suppressor gene ECRG4 interacts directly with TMPRSS11A (ECRG1) to inhibit cancer cell growth in esophageal carcinoma

<p>Abstract</p> <p>Background</p> <p>The esophageal carcinoma related gene 4 (ECRG4) was initially identified and cloned from human normal esophageal epithelium in our laboratory (GenBank accession no.<ext-link ext-link-id="AF325503" ext-link-type="gen">AF325503</ext-link>). ECRG4 has been described as a novel tumor suppressor gene associated with prognosis in esophageal squamous cell carcinoma (ESCC).</p> <p>Methods</p> <p>In this study, binding affinity assay in vitro and co-immunoprecipitation experiment in vivo were utilized to verify the physical interaction between ECRG4 and transmembrane protease, serine 11A (TMPRSS11A, also known as ECRG1, GenBank accession no. <ext-link ext-link-id="AF 071882" ext-link-type="gen">AF 071882</ext-link>). Then, p21 protein expression, cell cycle and cell proliferation regulations were examined after ECRG4 and ECRG1 co-transfection in ESCC cells.</p> <p>Results</p> <p>We revealed for the first time that ECRG4 interacted directly with ECRG1 to inhibit cancer cell proliferation and induce cell cycle G1 phase block in ESCC. Binding affinity and co-immunoprecipitation assays demonstrated that ECRG4 interacted directly with ECRG1 in ESCC cells. Furthermore, the ECRG4 and ECRG1 co-expression remarkably upregulatd p21 protein level by Western blot (P < 0.001), induced cell cycle G1 phase block by flow cytometric analysis (P < 0.001) and suppressed cell proliferation by MTT and BrdU assay (both P < 0.01) in ESCC cells.</p> <p>Conclusions</p> <p>ECRG4 interacts directly with ECRG1 to upregulate p21 protein expression, induce cell cycle G1 phase block and inhibit cancer cells proliferation in ESCC.</p