2,789 research outputs found

    Geological mapping of Sierra Leone : baseline assessment and next steps

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    Sierra Leone is a resource-rich country, with extensive known and potential mineral and petroleum resources. However, knowledge about the geology of the country is limited, with very little modern data in the public domain, and this hinders sustainable development of these resources for the national good. The lack of data is now being addressed by the Extractive Industries Technical Assistance Programme Phase 2 (EITAP 2) which is funded by the World Bank, and which aims to deliver a national airborne geophysical survey and subsequent geological mapping of the country (World Bank, 2017). Alongside EITAP 2, the UK government is funding the British Geological Survey (BGS) to work in partnership with relevant institutions in Sierra Leone, including the National Minerals Agency (NMA), the Petroleum Directorate (PD) and Fourah Bay College (FBC), to build their capacity to collect, manage and disseminate geological data. As part of that work, a field reconnaissance was carried out across Sierra Leone in January 2018 to assess the state of current geological mapping, visit mines and exploration projects, and to discuss how best to plan and carry out a mapping programme. The field trip was led by three British Geological Survey (BGS) staff members (Kathryn Goodenough, Jon Ford, and Darren Jones) together with 11 geologists from the NMA, two geologists from the PD, and two staff members from the Geology Department at Fourah Bay College. Pauline Scott and Avril Jamieson from the Department for International Development (DFID) joined the first two days of the trip. This report describes the conclusions arising from that field reconnaissance and associated literature review, including a baseline assessment of the current geological mapping of Sierra Leone, and suggestions for next steps. Some information is also derived from separate field visits to the AMR Gold licence area in the Loko Hills (April 2017) and coastal outcrops in the Lungi area (June 2017)

    An atomic scale comparison of the reaction of Bioglass® in two types of simulated body fluid

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    A class of melt quenched silicate glasses, containing calcium, phosphorus and alkali metals, and having the ability to promote bone regeneration and to fuse to living bone, is produced commercially as Bioglass. The changes in structure associated with reacting the bioglass with a body fluid simulant (a buffered Tris(hydroxymethyl)aminomethane growth medium solution or a blood plasma-like salt simulated body fluid) at 37°C have been studied using both high energy and grazing incidence x-ray diffraction. This has corroborated the generic conclusions of earlier studies based on the use of calcia–silica sol-gel glasses whilst highlighting the important differences associated with glass composition; the results also reveal the more subtle effects on reaction rates of the choice of body fluid simulant. The results also indicate the presence of tricalcium phosphate crystallites deposited onto the surface of the glass as a precursor to the growth of hydroxyapatite, and indicates that there is some preferred orientation to their growth

    Suppression of nuclear factor-κB activity in macrophages by chylomicron remnants: modulation by the fatty acid composition of the particles

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    Current evidence indicates that chylomicron remnants (CMR) induce macrophage foam cell formation, an early event in atherosclerosis. Inflammation also plays a part in atherogenesis and the transcription factor nuclear factor-κB (NF-κB) has been implicated. In this study, the influence of CMR on the activity of NF-κB in macrophages and its modulation by the fatty acid composition of the particles were investigated using macrophages derived from the human monocyte cell line THP-1 and CMR-like particles (CRLPs). Incubation of THP-1 macrophages with CRLPs caused decreased NF-κB activation and downregulated the expression of phospho-p65–NF-κB and phospho-IκBα (pIκBα). Secretion of the inflammatory cytokines tumour necrosis factor α, interleukin-6 and monocyte chemoattractant protein-1, which are under NF-κB transcriptional control, was inhibited and mRNA expression for cyclooxygenase-2, an NF-κB target gene, was reduced. CRLPs enriched in polyunsaturated fatty acids compared with saturated or monounsaturated fatty acids had a markedly greater inhibitory effect on NF-κB binding to DNA and the expression of phospho-p65–NF-κB and pIκB. Lipid loading of macrophages with CRLPs enriched in polyunsaturated fatty acids compared with monounsaturated fatty acids or saturated fatty acids also increased the subsequent rate of cholesterol efflux, an effect which may be linked to the inhibition of NF-κB activity. These findings demonstrate that CMR suppress NF-κB activity in macrophages, and that this effect is modulated by their fatty acid composition. This downregulation of inflammatory processes in macrophages may represent a protective effect of CMR which is enhanced by dietary polyunsaturated fatty acids

    Bi flux-dependent MBE growth of GaSbBi alloys

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    AbstractThe incorporation of Bi in GaSb1−xBix alloys grown by molecular beam epitaxy is investigated as a function of Bi flux at fixed growth temperature (275°C) and growth rate (1μmh−1). The Bi content is found to vary proportionally with Bi flux with Bi contents, as measured by Rutherford backscattering, in the range 0<x≤4.5%. The GaSbBi samples grown at the lowest Bi fluxes have smooth surfaces free of metallic droplets. The higher Bi flux samples have surface Bi droplets. The room temperature band gap of the GaSbBi epitaxial layers determined from optical absorption decreases linearly with increasing Bi content with a reduction of ~32meV/%Bi

    Identification and Characterization of Bioactive Components in Datura stramonium Leaves: an insight into Drugs Discovery

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    Medicines from plants help in treating ailments, but to utilize them effectively in the management of diseases requires the identification of potent phytochemicals relative to conventional drugs. These phytochemicals are compared with synthetics drugs in line with their treatment regimen. An investigation was designed to identify, and characterized the different phytochemicals in Datura stramonium (Jimson weed) leaves and compared them with conventional or standard drugs. The identified phytochemicals were blasted on the drugs bank website to find their correlation and relativity. GC/MS technique was used to analyze the phytochemicals. The results showed 80 different phytochemicals belonging to several categories of phytochemicals - alkaloids, flavonoids, terpenoids, saponins, amine, and steroids. The flavonoid class had - 1.24% of 5H-Dibenzo[c, f][1, 2] diazepine, 3, 8 dichloro-6,11-dihydro, at 3.702 RT, Alkaloid class has – 2.98% 2,6-Dibromobenzoquinone was detected at 4.403 RT, steroid – 2.98% Acetanilide, 2-chloro-4'-nitro- at 4.403 RT was obtained and Terpene – 2.05% of Methyl-beta.-[N-methylanilino]acrylate was detected at 4.719 RT, respectively. Most of the identified phytochemicals matched with synthetic drugs and confirmed the purpose of their applicability in traditional medicine. Considering the presence of numerous components and their correlation with conventional drugs, one can infer that this plant species has a good therapeutic application and can be utilized for health benefits

    Sharing data to build a medical information commons: from Bermuda to the Global Alliance

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    The Human Genome Project modeled its open science ethos on nematode biology, most famously through daily release of DNA sequence data based on the 1996 Bermuda Principles. That open science philosophy persists, but daily, unfettered release of data has had to adapt to constraints occasioned by the use of data from individual people, broader use of data not only by scientists but also by clinicians and individuals, the global reach of genomic applications and diverse national privacy and research ethics laws, and the rising prominence of a diverse commercial genomics sector. The Global Alliance for Genomics and Health was established to enable the data sharing that is essential for making meaning of genomic variation. Data-sharing policies and practices will continue to evolve as researchers, health professionals, and individuals strive to construct a global medical and scientific information commons.Robert Cook-Deegan, Rachel A. Ankeny, and Kathryn Maxson Jone

    A User‐Friendly Workbook to Facilitate Rapid and Accurate Rare Earth Element Analyses by ICP‐MS for Multispiked Samples

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    The rare earth elements (REEs) are widely used as geochemical tracers in the earth, planetary, and ocean sciences. Inductively coupled plasma‐mass spectrometry (ICP‐MS) has become the method of choice to analyze REE concentrations because it can rapidly measure the entire REE spectrum at the same time. This Technical Report presents a user‐friendly "REE Calculation Workbook" in Microsoft Excel to be used for calculating REE abundances in samples equilibrated with a multielement REE spike. This Workbook can be conveniently used to calculate REE concentrations in natural samples for spiked and unspiked elements measured by ICP‐MS. For the spiked elements, their concentrations are calculated using isotope dilution equations. Using these spiked elements as references, concentrations of the four mono‐isotopic REE elements, and other REE elements that are treated as mono‐isotopic elements (in our case, La and Lu), can be calculated. The REE Workbook can be easily set up for use with different REE spikes. Evaluation of our analytical quality using a quadrupole ICP‐MS on 10‐ml‐sized seawater samples shows that our analyses are comparable to high‐precision thermal ionization mass spectrometry (TIMS) studies, with much less time spent processing and analyzing, and with the added advantages of determining mono‐isotopic elements. An important result is the clear demonstration of enrichments in Gd and Er compared to neighboring elements in seawater samples. In addition, we compare and evaluate commonly used reference standards BCR‐1, Post‐Archean Australian Shale (PAAS), and North American Shale Composite (NASC)

    HadISDH: an updateable land surface specific humidity product for climate monitoring

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    HadISDH is a near-global land surface specific humidity monitoring product providing monthly means from 1973 onwards over large-scale grids. Presented herein to 2012, annual updates are anticipated. HadISDH is an update to the land component of HadCRUH, utilising the global high-resolution land surface station product HadISD as a basis. HadISD, in turn, uses an updated version of NOAA's Integrated Surface Database. Intensive automated quality control has been undertaken at the individual observation level, as part of HadISD processing. The data have been subsequently run through the pairwise homogenisation algorithm developed for NCDC's US Historical Climatology Network monthly temperature product. For the first time, uncertainty estimates are provided at the grid-box spatial scale and monthly timescale. HadISDH is in good agreement with existing land surface humidity products in periods of overlap, and with both land air and sea surface temperature estimates. Widespread moistening is shown over the 1973–2012 period. The largest moistening signals are over the tropics with drying over the subtropics, supporting other evidence of an intensified hydrological cycle over recent years. Moistening is detectable with high (95%) confidence over large-scale averages for the globe, Northern Hemisphere and tropics, with trends of 0.089 (0.080 to 0.098) g kg−1 per decade, 0.086 (0.075 to 0.097) g kg−1 per decade and 0.133 (0.119 to 0.148) g kg−1 per decade, respectively. These changes are outside the uncertainty range for the large-scale average which is dominated by the spatial coverage component; station and grid-box sampling uncertainty is essentially negligible on large scales. A very small moistening (0.013 (−0.005 to 0.031) g kg−1 per decade) is found in the Southern Hemisphere, but it is not significantly different from zero and uncertainty is large. When globally averaged, 1998 is the moistest year since monitoring began in 1973, closely followed by 2010, two strong El Niño years. The period in between is relatively flat, concurring with previous findings of decreasing relative humidity over land

    Theoretical study of the absorption spectra of the sodium dimer

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    Absorption of radiation from the sodium dimer molecular states correlating to Na(3s)-Na(3s) is investigated theoretically. Vibrational bound and continuum transitions from the singlet X Sigma-g+ state to the first excited singlet A Sigma-u+ and singlet B Pi-u states and from the triplet a Sigma-u+ state to the first excited triplet b Sigma-g+ and triplet c Pi-g states are studied quantum-mechanically. Theoretical and experimental data are used to characterize the molecular properties taking advantage of knowledge recently obtained from ab initio calculations, spectroscopy, and ultra-cold atom collision studies. The quantum-mechanical calculations are carried out for temperatures in the range from 500 to 3000 K and are compared with previous calculations and measurements where available.Comment: 19 pages, 8 figures, revtex, eps
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