Bioreduction of Se(IV) by Lactiplantibacillus plantarum NML21 and synthesis of selenium nanospheres Se(0).

Selenium nanospheres (SeNPs) show less toxicity and greater bioavailability than selenite salts. This research demonstrated the substantial tolerance and efficient conversion of Se(IV) into SeNPs by Lactiplantibacillus plantarum NML21. The bioreduction process of Se(IV) and the properties of SeNPs, including their morphology, particle size, and stability, were investigated with techniques including SEM, EDX, TEM, XPS, FT-IR, dynamic light scattering, XRD, and Raman spectroscopy. Under high selenium stress, certain cells displayed significant deformation and rupture, and released SeNPs as the main product of the bioreduction of Se(IV). These SeNPs were red, amorphous, zero-valent, and spherical, with an average diameter of 160 nm. Spectroscopic analysis highlighted that the functional groups of CO and CO are key to the bioreduction of Se(IV). The study suggested preliminary mechanisms for the bioreduction of Se(IV) and the formation and release of SeNPs by lactic acid bacteria. NML21 may therefore be a promising candidate for SeNPs synthesis.

Pseudo-targeted lipidomics insights into lipid discrepancies between yak colostrum and mature milk based on UHPLC-Qtrap-MS.

Yak milk is essential to maintain the normal physiological functions of herders in Tibetan areas of China. However, the lipid components of yak colostrum (YC) and mature milk (YM) have not been systematically studied. We employed a quantitative lipidomics to comprehensively describe the alterations in the milk lipid profile of lactating yaks. Herein, totally 851 lipids from 28 lipid subclasses in YC and YM were identified and screened for 43 significantly different lipids (SDLs; variable importance in projection > 1, fold change < 0.5 or > 2 with P < 0.05), with cholesterol ester (CE, 16:0) and triacylglycerol (TAG, 54:6 (20:5), 50:1 (16:0), 56:6 (20:5)) were the potential lipid biomarkers. Fourteen SDLs were modulated downwards, and 29 SDLs were modulated upwards in YM. Moreover, by analyzing lipid metabolic pathways in these SDLs, glycerophospholipid metabolism was the most critical. Our results furnish integral lipid details for evaluating yak milk's nutritional quality.

Research on bacterial community characteristics of traditional fermented yak milk in the Tibetan Plateau based on high-throughput sequencing.

Background: The Tibetan Plateau has an abundance of yak milk resources. The complex microbiota found in traditional fermented yak milk produced and sold by local Tibetans endows the yak milk with unique quality characteristics such as tissue morphology, flavor, and function. However, the diversity of bacterial flora in traditional fermented yak milk have not been elucidated. Methods: In this study, 15 samples of fermented yak milk were collected for 16S rRNA high-throughput sequencing to analyze the bacterial community composition and function. Results: After filtering for quality, 792,642 high-quality sequences were obtained, and 13 kinds of different phyla and 82 kinds of different genera were identified, of which the phylum Firmicutes (98.94%) was the dominant phylum, Lactobacillus (64.73%) and Streptococcus (28.48%) were identified as the dominant genus, in addition, the bacterial community richness and diversity were higher in Manang Village, followed by Bola Village. Bacterial community richness and diversity in Huage Village were relatively low. Based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) functional classification, the microorganisms in traditional fermented yak milk have rich metabolic functions (77.60%). These findings suggest that a large number of bacteria in traditional fermented yak milk contain abundant metabolic genes and can carry out a variety of growth and metabolic activities. This study established a theoretical foundation for further exploring the microbial flora of traditional fermented yak milk in Gannan.

Experimental Investigation of the High-Temperature Rheological and Aging Resistance Properties of Activated Crumb Rubber Powder/SBS Composite-Modified Asphalt.

Crumb rubber could form the active groups on the surface by interrupting the crosslinking bond to improve the compatibility with asphalt. While styrene-butadiene-styrene block copolymer (SBS)-modified asphalt has excellent comprehensive properties, it has poor anti-aging performance and a high cost. To explore the influence of composite modification of activated crumb rubber powder (ACR) and SBS on asphalt, modified asphalt samples with different modifiers and SBS contents were prepared. Conventional physical properties tests, a dynamic shear rheometer (DSR), and the thin-film oven test (TFOT) were used to study the conventional physical properties, high-temperature rheological properties, and aging resistance of asphalt. In addition, the action forms and distribution of modifiers in asphalt were observed by an optical microscope to characterize the micro-morphology of ACR/SBS composite-modified asphalt. Test results showed that after adding SBS, the softening point, ductility, and elastic recovery of ACR/SBS asphalt could be significantly improved, but the viscosity and softening point difference were also larger. At the same time, according to the complex shear modulus, phase angle, and rutting factor, SBS can effectively improve the high-temperature deformation resistance of ACR/SBS asphalt. The modified asphalt (ACR/SBS-2) had good high- and low- temperature performances, as well as an appropriate viscosity and low softening point difference, as a research object of aging. After short-term aging, the changes in the high- and low-temperature performances and workability of ACR/SBS asphalt were reduced. Taking the softening point as the target performance, the softening point of ACR/SBS asphalt was less affected by aging time and temperature, indicating that ACR/SBS asphalt was not sensitive to aging temperature and had good stability and aging resistance. From the micrograph by microscope, it was found that ACR/SBS asphalt could maintain a relatively stable polyphase structure for aging resistance.

Preliminary Feasibility Investigation on Reutilization of Recycled Crushed Clay Bricks from Construction and Demolition Waste for Cement-Stabilized Macadam.

Utilizing recycled crushed clay brick (RCB) from C&D waste in road engineering construction as the substitute for natural aggregates has attracted a lot of attention, which would be a promising step forward towards sustainable development and green construction. The objective of this study is to assess the feasibility of cement-stabilized macadam (CSM), incorporating various RCB fine aggregate substitution ratios. For this purpose, the physical and chemical properties of RCB fine aggregate was tested, and RCB exhibited a porous surface micro-morphology, high water absorption and pozzolanic activity. Subsequently, a comprehensive experimental investigation of modified CSM with RCB has been carried out based on laboratory tests concerning the mechanical and shrinkage properties. Results showed that higher RCB fine aggregate substitution ratio resulted in lower unconfined compressive strength, and the negative influence of RCB on unconfined compressive strength would decrease gradually, varying curing time; however, the higher the RCB substitution ratio was, the larger the indirect tensile strength at 90 d curing time of the late curing period was. CSM containing RCB had an overall increasing accumulative water loss rate, accumulative strain of dry shrinkage and average coefficient of dry shrinkage, except that 20% RCB resulted in an excellent dry shrinkage property. Moreover, RCB with pozzolanic activity reacted very slowly mainly at later ages, enhancing the interfacial transition zone.