Generation of Geochemical Exploration Targets from Regional Stream Sediment Data Using Principal Component and Factor Analysis: A Case Study of Kibaya-Kiteto, Manyara-Tanzania

A regional-scale stream sediment geochemical sampling was carried out with an average sampling density of one sample per nine square-kilometre in Kiteto District, Manyara Region. A total of 358 stream sediment samples were collected and analysed for major and trace elements by X-ray fluorescence (XRF) and fire assay with atomic absorption spectrometry (AAS) finish methods. In this study, Factor and Principal Component Multivariate (FPCM) analyses have been used to the stream geochemical data to delineate potential mineralization zones by plotting correlated factors as geochemical anomaly maps. Four factors that account for 73.7% of the total variance of the stream sediment geochemical data were established. Factor 1: Ni–Ba–Co–Cu–Sr which possibly defines the underlying metamorphosed granitic units with some contribution from mafic and ultramafic rocks. Factor 2: Cr–Zn–Mn which defines crustal forming elements reflecting the mafic rocks. Factor 3 which entails Rb and Pb probably attributed to metamorphosed granitic lithology. Factor 4 is arsenic, a chalcophile element with affinity to sulfide phases. The FPCM analyses have been successfully in delineating potential target areas for gold, nickel and copper exploration in the study area. Keywords:    Stream sediment; principal component; factor analysis; exploration targets; Kibaya-Kiteto, Manyara

Mineralogical and geochemical characteristics of graphite-bearing rocks at Chenjere Area, south-eastern Tanzania: Implications for the nature and quality of graphite mineralization

This study focused on the mineralogical and geochemical characteristics of graphite-bearing rocks at Chenjere area by conducting surface geological mapping, geochemical and petrographical analyses with the intention of characterizing the nature of graphite occurrence in these lithological units. This paper presents results of the flake size, grade and mineralization extension of graphite in the graphitic gneiss. Field observations, petrographic investigation and comparison with other studies indicate that graphite occurrence at the Chenjere area is of sedimentary origin which fall under syngenetic type. The petrographic study revealed that nature of metamorphism of rocks in the Chenjere area is of high grade (amphibolite facies). Both field observations and petrographic studies indicate that minerals in the rock associated with graphite include quartz, feldspar (mostly K-feldspar) and biotite. Further, the mineralized zones are concordant to the rest of the lithologies of the area and biotite gneiss is forming the hangingwall and footwall. The rocks’ foliation is generally NE striking and dipping SE with the dip amount ranging from 30 to 60 degrees. The graphite mineralization at the study area occurs as medium to coarse grained crystalline, flake type graphite with long axis of up to 1000 micrometres in size. Graphite flakes are disseminated and oriented in the host rock that represents a normal metamorphic fabric. Geochemical results indicate that graphite contents in the host graphitic gneiss range from 3.03 wt.% to 16.00 wt.%. Mineralogy and texture of the graphite at Chenjere area meet the standards required for industrial applications in various advanced technologies. Keywords: Graphite Mineralization, Flake Graphite, Chenjere Are

Mesenchymal Precursor Cells as Adjunctive Therapy in Recipients of Contemporary Left Ventricular Assist Devices

BACKGROUND: Allogeneic mesenchymal precursor cells (MPC) injected during left ventricular assist device (LVAD) implantation may contribute to myocardial recovery. This trial explores the safety and efficacy of this strategy. METHODS AND RESULTS: In this multi-center, double-blind, sham-procedure controlled trial, 30 patients were randomized (2:1) to intramyocardial injection of 25M MPCs or medium during LVAD implantation. The primary safety endpoint was incidence of infectious myocarditis, myocardial rupture, neoplasm, hypersensitivity reaction, and immune sensitization (90 days post-randomization). Key efficacy endpoints were functional status and ventricular function, while temporarily weaned from LVAD support (90 days post-randomization). Patients were followed until transplant or 12 months post-randomization, whichever came first. Mean age was 57.4 (±13.6) years, mean LVEF 18.1%, and 66.7% were destination therapy LVADs. No safety events were observed. Successful temporary LVAD weaning was achieved in 50% of MPC and 20% of control patients at 90 days (p=0.24); the posterior probability that MPCs increased the likelihood of successful weaning is 93%. At 90 days, 3 deaths occurred in control and none in MPC patients. Mean LVEF following successful wean was 24.0% (MPC=10) and 22.5% (Control=2) (p=0.56). At 12 months, 30% of MPC and 40% of control patients were successfully temporarily weaned from LVAD support (p=0.69) and 6 deaths occurred in MPC patients. Donor-specific HLA sensitization developed in 2 MPC and 3 control patients and resolved by 12 months. CONCLUSIONS: In this preliminary trial, administration of MPCs appeared to be safe and there was a potential signal of efficacy. Future studies will evaluate the potential for higher or additional doses to enhance the ability to wean LVAD recipients off support. CLINICAL TRIAL REGISTRATION INFORMATION: ClinicalTrials.gov. Identifier: NCT01442129