16 research outputs found

    Nickel – Iron Catalysts for Low Temperature Dry Reforming of Methane

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    Dry reforming of methane (DRM) offers benefit of consuming two important greenhouse gases(CH4 and CO2) in a single reaction to produce syngas. Ni-based catalysts have been studied for DRM. However, monometallic Ni catalysts deactivate mainly because of coking. We were motivated to include earth-abundant promoter metals to suppress coke formation and studied a series of bimetallic nickel-iron catalysts supported over TiO2 and TiO2-CeO2 at 550˚C and atmospheric pressure. This dissertation mainly focuses on various approaches to synthesize Ni-Fe catalysts and examines the effect of oxide support modification over optimum Ni-Fe/TiO2 catalyst. In this context, Ni-Fe catalysts supported over TiO2 were prepared by mainly two approaches – incipient wetness impregnation and co-precipitation methods. The total metal loading of Ni+Fe was maintained at 10 wt% while different ratios of Ni/Fe were investigated. We further explored the effect of oxide support modification by substituting 20 wt% TiO2 with CeO2 over a Ni-Fe/TiO2 catalyst showing high activity and simultaneous minimum coke formation. Bimetallic Ni-Fe catalysts were characterized by various techniques including Temperature Programmed Reactions (TPRs), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetry Analysis-Differential Thermogravimetry (TGA-DTG), Raman Spectroscopy and In-situ DRIFTS analysis. Conclusively, we found that addition of Fe is beneficial to inhibit coke deposition owing to its redox properties during low temperature DRM, while addition of CeO2 adds to coke inhibition property of Ni-Fe/TiO2 catalysts. However, Ni/Fe ratio of 3:1 is essential for better activity performance and simultaneous resistance to coke formation

    HYDROTREATING TUNGSTEN CATALYST FOR PRODUCTION OF GREEN DIESEL FROM BIODIESEL

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    The search for alternatives to petroleum-based fuels has led to the development of fuels from various sources, including renewable feedstocks such as fats and oils. Several types of fuels can be derived from these triacylglycerol-containing feedstocks. One of them is biodiesel, which is defined as the mono-alkyl esters of vegetable oils or animal fats. Biodiesel is produced by transesterifying the oil or fat with an alcohol such as methanol under mild conditions in the presence of a base catalyst. Another kind of product that can be obtained from lipid feedstocks is a fuel whose composition simulates that of petroleum-derived diesel fuel. This fuel termed as ‘‘green diesel’’, is produced from biodiesel by hydrodeoxygenation reaction at elevated temperature and pressure in the presence of a catalyst. Here, tungsten is used as hydrodeoxgenation catalyst to get green diesel from biodiesel. In this research, the effects of feed-stock, reduction and reaction temperatures, hydrogen flowrate and choice of promoter on the hydrodeoxygenation activity of the catalyst were examined. It is found that reduction and reaction temperatures are the two most important parameters for overall biodiesel conversion and yield of green diesel. The results for unpromoted and promoted tungsten catalyst are compared with the results for both the oxide and sulfide forms of the catalyst

    DNA methylation markers for oral pre-cancer progression: A critical review.

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    Although oral cancers are generally preceded by a well-established pre-cancerous stage, there is a lack of well-defined clinical and morphological criteria to detect and signal progression from pre-cancer to malignant tumours. We conducted a critical review to summarize the evidence regarding aberrant DNA methylation patterns as a potential diagnostic biomarker predicting progression. We identified all relevant human studies published in English prior to 30th April 2015 that examined DNA methylation (%) in oral pre-cancer by searching PubMed, Web-of-Science and Embase databases using combined key-searches. Twenty-one studies (18-cross-sectional; 3-longitudinal) were eligible for inclusion in the review, with sample sizes ranging from 4 to 156 affected cases. Eligible studies examined promoter region hyper-methylation of tumour suppressor genes in pathways including cell-cycle-control (n=15), DNA-repair (n=7), cell-cycle-signalling (n=4) and apoptosis (n=3). Hyper-methylated loci reported in three or more studies included p16, p14, MGMT and DAPK. Two longitudinal studies reported greater p16 hyper-methylation in pre-cancerous lesions transformed to malignancy compared to lesions that regressed (57-63.6% versus 8-32.1%; p<0.01). The one study that explored epigenome-wide methylation patterns reported three novel hyper-methylated loci (TRHDE; ZNF454; KCNAB3). The majority of reviewed studies were small, cross-sectional studies with poorly defined control groups and lacking validation. Whilst limitations in sample size and study design preclude definitive conclusions, current evidence suggests a potential utility of DNA methylation patterns as a diagnostic biomarker for oral pre-cancer progression. Robust studies such as large epigenome-wide methylation explorations of oral pre-cancer with longitudinal tracking are needed to validate the currently reported signals and identify new risk-loci and the biological pathways of disease progression

    Single nucleotide polymorphisms as markers of genetic susceptibility for oral potentially malignant disorders risk: Review of evidence to date

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    SummaryBackgroundOral cancers are preceded by oral potentially malignant disorders (OPMD). Understanding genetic susceptibility for OPMD risk could provide an opportunity for risk assessment of oral cancer through early disease course. We conducted a review of single nucleotide polymorphism (SNP) studies for OPMD risk.MethodsWe identified all relevant studies examining associations of SNPs with OPMD (leukoplakia, erythroplakia and oral sub-mucous fibrosis) conducted world-wide between January, 2000 and February, 2016 using a combined keyword search on PubMed. Of these, 47 studies that presented results as odds ratios and 95% CI were considered for full review.ResultsThe majority of eligible studies that explored candidate gene associations for OPMD were small (N<200 cases), limiting their scope to provide strong inference for any SNP identified to date in any population. Commonly studied SNPs were genes of carcinogen metabolism (n=18 studies), DNA repair (n=11 studies), cell cycle control (n=8 studies), extra-cellular matrix alteration (n=8 studies) and immune-inflammatory (n=6 studies) pathways. Based on significant associations as reported by two or more studies, suggestive markers included SNPs in GSTM1 (null), CCND1 (G870A), MMP3 (-1171; promotor region), TNFα (-308; rs800629), XPD (codon 751) and Gemin3 (rs197412) as well as in p53 (codon 72) in Indian populations. However, an equal or greater number of studies reported null or mixed associations for SNPs in GSTM1 (null), p53 (codon 72), XPD (codon 751), XRCC (rs25487 C/T), GSTT1 (null) and CYP1A1m1 (MspI site).ConclusionCandidate gene association studies have not yielded consistent data on risk loci for OPMD. High-throughput genotyping approaches for OPMD, with concurrent efforts for oral cancer, could prove useful in identifying robust risk-loci to help understand early disease course susceptibility for oral cancer

    Association of Long-Term Exposure to Fine Particulate Matter and Cardio-Metabolic Diseases in Low- and Middle-Income Countries: A Systematic Review.

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    : Background: Numerous epidemiological studies indicated high levels of particulate matter less than2.5 μm diameter (PM2.5) as a major cardiovascular risk factor. Most of the studies have been conducted in high-income countries (HICs), where average levels of PM2.5 are far less compared to low- and middle- income countries (LMICs), and their socio-economic profile, disease burden, and PM speciation/composition are very different. We systematically reviewed the association of long-term exposure to PM2.5 and cardio-metabolic diseases (CMDs) in LMICs. METHODS: Multiple databases were searched for English articles with date limits until March 2018. We included studies investigating the association of long-term exposure to PM2.5 (defined as an annual average/average measure for 3 more days of PM2.5 exposure) and CMDs, such as hospital admissions, prevalence, and deaths due to CMDs, conducted in LMICs as defined by World Bank. We excluded studies which employed exposure proxy measures, studies among specific occupational groups, and specific episodes of air pollution. RESULTS: A total of 5567 unique articles were identified, of which only 17 articles were included for final review, and these studies were from Brazil, Bulgaria, China, India, and Mexico. Outcome assessed were hypertension, type 2 diabetes mellitus and insulin resistance, and cardiovascular disease (CVD)-related emergency room visits/admissions, death, and mortality. Largely a positive association between exposure to PM2.5 and CMDs was found, and CVD mortality with effect estimates ranging from 0.24% to 6.11% increased per 10 μg/m3 in PM2.5. CVD-related hospitalizations and emergency room visits increased by 0.3% to 19.6%. Risk factors like hypertension had an odds ratio of 1.14, and type 2 diabetes mellitus had an odds ratio ranging from 1.14-1.32. Diversity of exposure assessment and health outcomes limited the ability to perform a meta-analysis. CONCLUSION: Limited evidence on the association of long-term exposure to PM2.5 and CMDs in the LMICs context warrants cohort studies to establish the association

    Single nucleotide polymorphisms as markers of genetic susceptibility for oral potentially malignant disorders risk: Review of evidence to date.

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    BACKGROUND: Oral cancers are preceded by oral potentially malignant disorders (OPMD). Understanding genetic susceptibility for OPMD risk could provide an opportunity for risk assessment of oral cancer through early disease course. We conducted a review of single nucleotide polymorphism (SNP) studies for OPMD risk. METHODS: We identified all relevant studies examining associations of SNPs with OPMD (leukoplakia, erythroplakia and oral sub-mucous fibrosis) conducted world-wide between January, 2000 and February, 2016 using a combined keyword search on PubMed. Of these, 47 studies that presented results as odds ratios and 95% CI were considered for full review. RESULTS: The majority of eligible studies that explored candidate gene associations for OPMD were small (N<200 cases), limiting their scope to provide strong inference for any SNP identified to date in any population. Commonly studied SNPs were genes of carcinogen metabolism (n=18 studies), DNA repair (n=11 studies), cell cycle control (n=8 studies), extra-cellular matrix alteration (n=8 studies) and immune-inflammatory (n=6 studies) pathways. Based on significant associations as reported by two or more studies, suggestive markers included SNPs in GSTM1 (null), CCND1 (G870A), MMP3 (-1171; promotor region), TNF? (-308; rs800629), XPD (codon 751) and Gemin3 (rs197412) as well as in p53 (codon 72) in Indian populations. However, an equal or greater number of studies reported null or mixed associations for SNPs in GSTM1 (null), p53 (codon 72), XPD (codon 751), XRCC (rs25487 C/T), GSTT1 (null) and CYP1A1m1 (MspI site). CONCLUSION: Candidate gene association studies have not yielded consistent data on risk loci for OPMD. High-throughput genotyping approaches for OPMD, with concurrent efforts for oral cancer, could prove useful in identifying robust risk-loci to help understand early disease course susceptibility for oral cancer

    Leveraging Existing Cohorts to Study Health Effects of Air Pollution on Cardiometabolic Disorders:India Global Environmental and Occupational Health Hub

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    Air pollution is a growing public health concern in developing countries and poses a huge epidemiological burden. Despite the growing awareness of ill effects of air pollution, the evidence linking air pollution and health effects is sparse. This requires environmental exposure scientist and public health researchers to work more cohesively to generate evidence on health impacts of air pollution in developing countries for policy advocacy. In the Global Environmental and Occupational Health (GEOHealth) Program, we aim to build exposure assessment model to estimate ambient air pollution exposure at a very fine resolution which can be linked with health outcomes leveraging well-phenotyped cohorts which have information on geolocation of households of study participants. We aim to address how air pollution interacts with meteorological and weather parameters and other aspects of the urban environment, occupational classification, and socioeconomic status, to affect cardiometabolic risk factors and disease outcomes. This will help us generate evidence for cardiovascular health impacts of ambient air pollution in India needed for necessary policy advocacy. The other exploratory aims are to explore mediatory role of the epigenetic mechanisms (DNA methylation) and vitamin D exposure in determining the association between air pollution exposure and cardiovascular health outcomes. Other components of the GEOHealth program include building capacity and strengthening the skills of public health researchers in India through variety of training programs and international collaborations. This will help generate research capacity to address environmental and occupational health research questions in India. The expertise that we bring together in GEOHealth hub are public health, clinical epidemiology, environmental exposure science, statistical modeling, and policy advocacy

    Nations within a nation: variations in epidemiological transition across the states of India, 1990–2016 in the Global Burden of Disease Study

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    18% of the world's population lives in India, and many states of India have populations similar to those of large countries. Action to effectively improve population health in India requires availability of reliable and comprehensive state-level estimates of disease burden and risk factors over time. Such comprehensive estimates have not been available so far for all major diseases and risk factors. Thus, we aimed to estimate the disease burden and risk factors in every state of India as part of the Global Burden of Disease (GBD) Study 2016

    Impact of Intellectual Property Rights on International Trade: Evidence from India

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    200-210This paper analyzed the effect of intellectual property rights (IPR) on Indian trade by employing Johansen&rsquo;s Co-integration test, VECM and Granger Causality approach. Annual time series data on variables viz. trade, patents, copyrights, trademark for Indian economy, stemming from 1996-97 to 2013-14 have been used in analysis. The empirical result shows that there exists significant long run relationship between Indian trade and export as well as import of patent related commodities It also suggests that all the series are found to be co-integrated of order one. It means export as well as import of patent related commodities are significantly contributing towards Indian trade. The short run Vector Error Correction Model (VECM) reveals that Indian Trade (LNTRADE) respond significantly to re-establish the equilibrium relationship whenever there is any disturbance in the system in long run. Further Granger causality test exhibits that there exists unidirectional causality running from Indian trade to export and import of patent related commodities, export of trademark related commodities whereas causality runs from export and import of copyright related commodities to Indian trade

    Transformation of pancreatic nonfunctioning neuroendocrine tumor into metastatic insulinoma: A rare case report

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    Key Clinical Message Pancreatic neuroendocrine tumors can be classified as functional or nonfunctional based on hormone secretion. Management of each entity is different, with nonfunctional tumors being treated with traditional chemotherapy while functional tumors respond well to antihormonal therapy and immunologic agents. The conversion of one nonfunctional tumor into a functional tumor is an exceedingly rare event that complicates the overall management of these patients. In this report, we present the case of a 73‐year‐old woman who developed the conversion from a nonfunctional into a functional tumor and discuss the management options considered
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