Transmission electron microscopy linked with energy-dispersive X-ray spectroscopy (TEM-EDX) was applied to characterize mineralogical signals of weathering processes in the Di Linh bentonite deposit (Vietnam) and to visualize the effects of Na activation on the smectitic phases. Modelling of X-ray diffraction patterns (oriented mount) was applied in order to refine the computed structural formula. X-ray diffraction, X-ray fluorescence and Fouriertransform infrared spectroscopy (FT-IR) methods were also applied to verify the TEM-EDX results. An Excel-based routine has been developed in this research to allow fast computation of structural formulae and classification of the investigated clay particles. This routine supports the acquirement of 100-300 TEM-EDX analyses as a representative set of individual particles for each sample. The Excel-based routine involves end members of different clay-mineral groups and interstratifications with two or three members (e.g. illite-smectite interstratifications -IS-ml; dioctahedral vermiculite-smectite interstratifications -diVS-ml; and kaolinite-montmorillonite-dioctahedral vermiculite interstratifications -KSV-ml). The routine is now freely available. According to the identification procedure, the <2 mm fraction of the Di Linh bentonite (Vietnam) is composed mainly of K-and charge-deficient illite-smectite interstratifications (or diVS-ml): montmorillonite-rich randomly ordered (R0) type and illite-rich regularly ordered (R1) type. Additionally, Fe-poor KSV-ml was identified. Industrial Na activation of the Di Linh bentonite resulted in an increase of the R1 diVS-ml portion and dissolution of a large part of the smectite-rich phases. The TEM-EDX approach also gave analytical proof of a sedimentary process for Di Linh smectite. The parent muscovite was altered in two different environments: (i) K-leaching and layer-wise alteration into kaolinite (weathering), and (ii) further edge-controlled alteration of mica into lath-like montmorillonite particles associated with a dissolution of kaolinite layers from the former kaolinite-mica intergrowths by heat impact (basalt flow).
Graphite, especially, high quality graphite can be used in many industrial applications including metallurgy, batteries, fuel cells, and refractories. In 2011, Vietnam Ministry of Natural Resources and Environment issued a mineral exploration license to explore Bao Ha graphite deposit, Bao Yen district, Lao Cai Province. The studied samples were taken from 3 drill holes of the Bao Ha largest ore body. Different methods including light microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and carbon and sulfur analyzer were performed to identify its lithological and mineralogical characteristics as well as graphite quality, then propose a wise use of the resource. The Bao Ha graphite is characterized as disseminated flake graphite in massive form, which developed in the sillimanite schist and quartz-biotite schist of the Ngoi Chi formation. Graphite flakes occur as distorted clusters of flaky plates/flakes within 50÷500 m, which is the medium size in comparison with the general grain size of graphite flake. Graphite particle makes up 33÷43% by volume and graphitic content (Cg) makes up 10.0÷11.7 wt.%. Impurities include mainly quartz, biotite, and feldspar (combining of K-feldspar and anorthite, the primary ore) or kaolinite (the weathered ore). This graphite ore should be refined to reach an ore concentration of at least 90% Cg for domestic industries of metallurgy, batteries, thermal materials, and refractories as well as for exports.
A cross-sectional descriptive study was conducted from August 2021 to September 2021 to describe the epidemiological characteristics of COVID-19 patients at the field hospital in Dong Thap Community College. The study collected epidemiological data from 240 subjects. The results show that the male/female ratio is 1.2/1; the mean age was 29.2±15.1(1-65) years old; the proportion of subjects having contact with the pandemic area is 90%. The percentage of patients who caught Covid-19 from their family is the highest (62.1%), followed by the number of patients with an unknown source of infection (24.6%) and the number of patients who caught Covid-19 from community transmission (13.3%). The mean time between infection to hospitalization was 4.8 days. The percentage of subjects having 1st dose of vaccine is 12.5%. Most patients acknowledge the COVID-19 pandemic and know the modes of transmission of the SARS-CoV-2 virus. Most of the sick people practiced adequately or inadequately 5K measures in the community and did not practice disease prevention measures at home. The goals of this study are: i) Contributing to a general assessment of epidemiological factors and the accumulated understanding of the disease of COVID-19 patients in general, and COVID-19 subjects at the field hospital of Dong Thap Community College in particular; and ii) Contributing to the development of better disease prevention measures. Keywords: COVID-19, SARS-CoV-2, epidemiological characteristics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.