Utilization of rock dust to produce roof tiles and its effects on properties of tiles, mixed with red clay collected from Naogaon district of Bangladesh were investigated. After proper characterization of the raw materials, tiles were prepared with different percentages of rock dust (10-50%) mixed with clay sintered from 850-1100 • C temperature. Rock dust has been found good for using as fluxing material after XRF study. The samples were tested for different properties such as water absorption, porosity, mechanical strength, linear shrinkage, and bulk density. The strength values have exceeded the minimum standard requirement for roof tiles with low water absorption in most samples. The results obtained made it possible to conclude about the possibility of producing roof tiles incorporating up to 40% of rock dust having better properties (lower water absorption 6.5%, strength value 31.97 MPa) fired at 900 • C. Therefore these dust acts as a fluxing agent and reducing the sinteringtemperature of the clay material.

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This study synthesized silver nanoparticles (Ag-NPs) using silver nitrate (AgNO3) as the ion source and sodium tripolyphosphate (STPP) as reducing as well as capping agents. The synthesized Ag-NPs were confirmed initially using Ag-NPs specific λmax at 410 nm with UV-Vis spectrophotometry and homogenously distributed, 100–300 nm size, and round-shaped particles were realized through atomic force microscopy (AFM) and transmission electron microscopy (TEM) image analysis. The various reaction condition-based studies revealed 0.01 M AgNO3 yields maximum particle after 4 h reduction with 1% STPP. Bacillus spp. (n = 23/90) and Pseudomonas spp. (n = 26/90) were isolated from three different poultry farms for evaluating the antibacterial activity of Ag-NPs. Among the PCR confirmed isolates, 52% (12/23) Bacillus spp. were resistant to ten antibiotics and 65% (17/26) Pseudomonas spp. were resistant to eleven antibiotics. The representative resistant isolates were subjected to antibacterial evaluation of synthesized Ag-NPs following the well diffusion method, revealing the maximum sensitive zone of inhibition 19 ± 0.2 mm against Bacillus spp. and 17 ± 0.38 mm against Pseudomonas spp. The minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) of Ag-NPs were 2.1 μg/ml and 8.4 μg/ml, respectively, for broad-spectrum application. Finally, the biocompatibility was determined by observing the viability of Ag-NP-treated BHK-21 cell through trypan blue-based exclusion assay revealing nonsignificant decreased of cell viability ≤2MIC doses. Thus, the synthesized Ag-NPs were proven as biocompatible and sensitive to both Gram-positive and Gram-negative bacteria of the poultry farm environmental samples.

Sediments from stable sand bars along a 40 km section of the Brahmaputra River in northern Bangladesh were analyzed for their major, trace and rare earth element contents to determine their provenance, compositional maturity, source area weathering and tectonic setting. Geochemically, the sediments were classified as litharenites and the Index of Compositional Variability (ICV) varied between 1.4 and 2.0, indicating low compositional and mineralogical maturity. A high mean SiO2 concentration (72.9 wt.%) and low Al2O3 (11.1 wt.%) were consistent with a low abundance of shale and clay components. The depletion of the oxide components Na2O, CaO and K2O relative to average upper crustal compositions (UCC) reflected loss of feldspar during chemical weathering in the source region. Average TiO2 values for most samples were higher than average crustal levels, consistent with the northern section of the Brahmaputra River being a potential resource for valuable Fe-Ti oxide heavy minerals. Major and trace element ratios indicated the sediments represented erosional products from typical felsic upper continental crustal materials with contamination (30%–40%) from more intermediate/mafic compositions. The rare earth element patterns showed negative Eu anomalies (0.57–0.71), indicating they were derived mainly from fractionated felsic rocks. Resemblance of the sediment compositions to mean compositions from Higher Himalaya crystalline rocks pointed to these being potential source rocks but with components from a mafic source also present. Major element chemistries and low to intermediate weathering indices for all sediments indicated a lack of substantial chemical weathering. Evidence from tectonic discrimination diagrams suggested the Brahmaputra River sediments were derived from rock types that formed in a transitional tectonic setting ranging from an ancient passive margin to an active continental margin. Deposition occurred under cool to semi-arid climatic conditions in an oxic environment.