Nonlinear Vibrational Analysis of Nanobeams Embedded in an Elastic Medium including Surface Stress Effects

Due to size-dependent behavior of nanostructures, the classical continuum models are not applicable for the analyses at this submicron size. Surface stress effect is one of the most important matters which make the nanoscale structures have different properties compared to the conventional structures due to high surface to volume ratio. In the present study, nonlinear free vibrational characteristics of embedded nanobeams are investigated including surface stress effects. To this end, a thin surface layer is assumed on the upper and lower surfaces of the cross section to separate the surface and bulk of nanobeams with their own different material properties. Based on harmonic balance method, closed-form analytical solution is conducted for nonlinear vibrations to obtain natural frequencies of embedded nanobeams with and without considerations of surface elasticity and residual surface tension effects corresponding to the various values of nondimensional amplitude, elastic foundation modulus, and geometrical variables of the system. Selected numerical results are given to indicate the influence of each one in detail

Co-products in maize-soybean growing-pig diets altered in vitro enzymatic insoluble fibre hydrolysis and fermentation in relation to botanical origin

The study examined the effects of botanical factors and fermentation-based, high-level dilution of co-product feeds in maize–soybean growing-pig diets on enzymatic insoluble fibre hydrolysis and fermentation. Feed insoluble fibre residues that were recovered after pepsin-pancreatin digestion were subjected to Roxazyme® G2 (Roxazyme) versus Viscozyme L® V2010 (control) hydrolysis, and to 64-hour fermentation using pig faecal inoculum. The control diet was a 13 MJ metabolizable energy, 141 g total dietary fibre/kg dry matter maize-meal/hominy chop-soybean diet, which was diluted with maize cob, soybean hulls, barley brewer’s grains, lucerne hay or wheat bran in 12 MJ metabolizable energy, 246 g total dietary fibre/kg dry matter iso-nutrient, single co-product test diets. Fermentable insoluble fibre was employed in a computerized iterative selection of ingredients in two iso-nutrient 11 MJ metabolizable energy 319 total dietary fibre/kg dry matter mixed fibre test diets for maximal contrast (high (HF) versus low (LF)) in fermentability. Insoluble fibre extractive pepsin-pancreatin digestibility differed between feed ingredients, and the single co-product test diets, and between the HF and LF mixed co-product diets. Fibre digestibility depended on both the origin and enzyme, with interaction, whereby carbohydrases expressed similar low (0.04 - 0.05) insoluble fibre digestibility for maize cob, moderate (0.12) digestibility for wheat bran and brewer’s grain, with inferior Roxazyme G2 digestibility for maize hominy chop (0.02 vs 0.10) and meal (0.04 vs 0.16), dehulled soybean meal (0.02 vs 0.17), lucerne hay (0.08 vs 0.18), and soybean hulls (0.05 vs 0.33). Co-product-enzyme affinities were expressed in single fibre diets. Low Roxazyme-basal fibre affinity limited its comparative single co-product (0.03 - 0.07 vs 0.16 - 0.22) HF (0.07 vs 0.17) and LF (0.4 vs 0.20) dietary fibre digestibility. Screening for HF/LF did not affect enzymatic digestion, though enzyme combination increased HF, but not LF digestibility. Gas and short chain fatty acid production predicted fermentability proportionately in the declining order of dehulled soybean ≥ maize ≥ soy hulls ≥ maize hominy chop > wheat bran >lucerne hay ≥ brewer’s grain = maize cob. Induced HF and LF contrast was significant. Co-product fibre enrichment decreased fermentability for all except the soy hull and HF diets. Cereal fibre yielded proportionately less acetate, with more propionate and butyrate, and a greater butyrate shift for maize fibre. The HF fibre induced more ACE and less butyrate. Biomarkers of deleterious proteolytic fermentation were high for lucerne (iso-butyrate) and soy hulls (iso-valerate). In conclusion, high-level and fermentation based co-product feed dilution into maize-soybean growing pig diets altered enzymatic insoluble fibre hydrolysis and fermentation in relation to botanical origin. Roxazyme expressed weak hydrolytic potency on maize and soybean insoluble fibre.Keywords: fermentation gas, fermentation kinetics, fibre fermentability, insoluble non-starch polysaccharides, non-starch polysaccharide degrading enzymes, proteolytic fermentation, short-chain fatty acid

Pathogen infection influences a distinct microbial community composition in sorghum RILs

AIMS: The rhizosphere microbiome substantially affects plant health, yet comparatively little is known regarding the foliar community dynamics. Here, we examine the relationship between the microbiota and their response to natural infection by pathogens. METHODS: We established an experimental system using a set of sorghum recombinant inbred lines (RILS). These RILS included four models denoted as resistant, moderately resistant, susceptible and highly susceptible. A combination of 16S rRNA and ITS gene amplicon approaches was used to assess bacteria and fungi, respectively, in foliar samples. RESULTS: We show that the foliar microbiome differs substantially in asymptomatic and symptomatic RILs subsequent to natural infection by pathogens. A significant association was found between plant health and microbial community structure. Our analyses revealed several distinct fungal and bacterial pathogens. These pathogens included Gibberella and Pantoea genera, which were associated with the highly susceptible group. In addition to these pathogens, we also found signatures for Ascochyta, a known plant pathogenic genus. Members of the bacterial genus Methylorubrum and the fungal genus Hannaella, both known to exhibit plant growthpromoting (PGP) traits, were associated with the resistant and moderately resistant groups. These data also reveal numerous highly diverse fungal and bacterial taxa in RILs that did not show symptoms. We also found taxonomic differences between the microbiota hosted by the symptomatic and asymptomatic RILs. CONCLUSIONS: Together, these data suggest that pathogen infection may result in distinct microbiota. These results suggest that highly diverse microbiome may promote the plants ability to resist the effects of pathogens potentially contributing to plant health.The National Research Foundation, the Agricultural Research Council and the University of South Africa.http://link.springer.com/journal/11104pm2022BiochemistryGeneticsMicrobiology and Plant Patholog

A genomic catalog of Earth’s microbiomes

The reconstruction of bacterial and archaeal genomes from shotgun metagenomes has enabled insights into the ecology and evolution of environmental and host-associated microbiomes. Here we applied this approach to >10,000 metagenomes collected from diverse habitats covering all of Earth’s continents and oceans, including metagenomes from human and animal hosts, engineered environments, and natural and agricultural soils, to capture extant microbial, metabolic and functional potential. This comprehensive catalog includes 52,515 metagenome-assembled genomes representing 12,556 novel candidate species-level operational taxonomic units spanning 135 phyla. The catalog expands the known phylogenetic diversity of bacteria and archaea by 44% and is broadly available for streamlined comparative analyses, interactive exploration, metabolic modeling and bulk download. We demonstrate the utility of this collection for understanding secondary-metabolite biosynthetic potential and for resolving thousands of new host linkages to uncultivated viruses. This resource underscores the value of genome-centric approaches for revealing genomic properties of uncultivated microorganisms that affect ecosystem processes

A survey of the knowledge, use, and adoption of emerging technologies by academics in an Open Distance Learning environment

The realisation of the advantages offered by e-learning accompanied by the use of various emerging information technologies has resulted in a noticeable shift by academia towards e-learning. An analysis of the use, knowledge and adoption of emerging technologies by academics in an Open Distance Learning (ODL) environment at the University of South Africa (UNISA) was undertaken in this study. The aim of the study was to evaluate the use, knowledge and adoption of emerging e-learning technologies by the academics from the selected schools. The academics in the Schools of Arts, Computing and Science were purposively selected in order to draw on views of academics from different teaching and educational backgrounds. Questionnaires were distributed both electronically and manually. The results showed that academics in all the Schools were competent at the use of information technology tools and applications such as emailing, word-processing, Internet, myUnisa (UNISA’s online teaching platform), and Microsoft PowerPoint and Excel. An evaluation of the awareness of different emerging technological tools showed that most academics were aware of Open Access Technologies, Social Networking Sites, Blogs, Video Games and Microblogging Platforms. While the level of awareness was high for these technologies, the use by the academics was low. At least 62.3% of the academics indicated willingness to migrate to online teaching completely and also indicated the need for further training on new technologies. A comparison of the different schools showed no statistically significant difference in the use, knowledge and willingness to adopt technology amongst the academics

An Evaluation of the Cumulative Surface Water Pollution on Selected Areas within the Consolidated Main Reef Area, Roodepoort, South Africa

Mining has long been at the center of the South African economy and has contributed to significant developments within the country. However, despite the large economic impact, surface water pollution due to mining is prevalent in most of the country's water catchments. Surface water in many areas of the central Roodepoort area in Johannesburg, South Africa, has also been impacted primarily by mining activities. The surface water quality for the Bosmontspruit, Russell's Stream, and the New Canada Dam was assessed in this study from October 2010 to March 2011. Physicochemical and biological characteristics of the water were determined for eight monitoring points, and the results obtained were compared with the in-stream water quality guidelines for the Klip River catchment and the South African Water Quality Guidelines. A trend noticed throughout the sampling period was the noncompliance to the set target water quality ranges (TWQRs) in the levels of total dissolved solids (TDS) and dissolved oxygen (DO). The results indicate that concentrations of iron, aluminum, nickel, manganese, and potassium were above the permissible limits across the Bosmontspruit and Russell's Stream. Excessive fecal coliforms and ammonium pollution were also detected in the Bosmontspruit. Additionally, during the monitoring period, it was noted that the water was being utilized for domestic purposes, and may pose health hazards due to poor water quality

WASH and drinking water quality considerations in schools in reflection of the sustainable development goals – a review

Poor drinking water quality has been linked to negative health outcomes across the world. Drinking water quality is an essential part of safe water, sanitation, and hygiene (WASH). Safe WASH in schools is linked with the achievement of sustainable development goals (SGDs), specifically, SDG 6. It is unclear whether water quality is always assessed as part of WASH in schools. This study focused on determining the consideration of water quality aspects during WASH assessment in schools by examining published studies. A systematic online review of the literature was conducted to identify studies that reported on the assessment of WASH facilities in schools. Titles, abstracts, and full text of retrieved articles were screened. Seventy-five studies were identified. Thirty-two studies considered drinking water quality analysis as part of WASH in schools. Chemical (66%), microbial (59%), and physical (38%) parameters were included in drinking water quality analysis, with lead (Pb), and Escherichia coli being mostly included. This study reveals that some studies did not include an evaluation of drinking water quality, though it reflects an important exposure pathway between WASH services and health outcomes. It is, therefore, recommended that routine water quality monitoring be included in school WASH to ensure learner's health is protected. HIGHLIGHTS Most researchers neglect the analysis of water quality in school WASH programmes.; The current study emphasizes the importance of drinking water quality analysis in schools.; Concerns about water quality exist in both developed and underdeveloped countries.; The relationship between WASH and achieving the sustainable development goals (SDGs) in schools is a necessity.; WASH intervention for water quality is key to safeguard learner's health.

An evaluation of a mesophilic reactor for treating wastewater from a Zimbabwean potato-processing plant

An evaluation of anaerobic treatment of potato-processing wastewater using an up flow Anaerobic Sludge Bed (UASB) reactor at 37°C was conducted. Wastewater from a potato-processing plant in Harare, with an average of 6.8 g COD/l, (COD = chemical oxygen demand) a high concentration of total solids (up to 6725 mg/l) and low pH of 4 - 4.9 was subjected to anaerobic treatment in an UASB reactor. The start up period, which was indicated by gas production and stabilization of COD reduction was 21 days. The organic loading rates (OLRs) investigated varied between 1.3 g COD/l/d and 13.1 g COD/l/d, the maximum methane yield was 0.3 l/g CODremoved at an organic loading rate of 6.6 g COD/l/d. An increase in OLRs to values above 13.1 g COD/ l/d resulted in digester failure. The maximum treatment efficiency (TE) in terms of COD reduction achieved was 90% at a hydraulic retention time (HRT) of 2.1 d and OLR of 3.3 g COD/l/d. The TE was reduced at higher reactor influent velocities, with a minimum TE (71%) recorded at HRT of 0.5 d. Total solids (TS) removal was inconsistent with an average reduction around 50% and phosphorus removal was poor and erratic. pH from the effluent oscillated around 7 with a notable decrease from 7.8 to 6.2 at HRT of 0.5 d. Based on these observations, the UASB process has potential to treat potato-processing wastewater as a pretreatment step before discharge into municipal sewerage system of Harare.Key words: UASB reactor, potato wastewater, anaerobic digestion, methane yield, organic loading rate