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The marine microbial biomass, Novacq™, a useful feed additive for postlarvae and juvenile Litopenaeus vannamei
No full textAlthough Litopenaeus vannamei is the most produced and researched shrimp species worldwide, there are no published studies evaluating the use of the microbial biomass, Novacq™, in L. vannamei feeds. This study investigated the effects of supplementing Novacq™ at 100 g kg in practical and commercial feeds in postlarvae 12 (PL 12) and juvenile white leg shrimp. Three experiments were carried out. In Experiment 1, PL12 were fed for 21 days with a Control, Novacq™ or Commercial feed. The Novacq feed was equal in PL12 performance to the Commercial diet and superior to the Control (final individual weight = 0.169, 0.167 and 0.087 g; percentage weight gain = 8014, 7956 and 4091% for Novacq™, Commercial and Control feeds, respectively). No statistical differences in survival, coefficient of variation and daily feed offered were observed across dietary treatments. In Experiments 2 and 3 the performance of juvenile shrimp fed practical and Commercial feeds supplemented with Novacq™ for 42 days, respectively. In Experiment 2, Novacq™ feed outperformed the Control feed by improving survival (89 vs. 51%), final individual weight (7.4 vs. 3.5 g), weight gain (7.1 vs. 3.2 g), and percentage weight gain (1997 vs. 898%). In Experiment 3 supplementing Novacq™ into the Commercial feed improved performance (final individual weight = 6.4 vs. 5.5 g, weight gain = 6.0 vs. 5.1 g, and percentage weight gain = 1712 vs 1443%) and reduced the coefficient of variation (19 vs 53%). Shrimp fed feeds containing Novacq™ also displayed numerically reduced daily feed offered and estimated feed conversion ratio values in comparison to the other dietary treatments. Whole-body composition was similar across dietary treatments. In summary, supplementation of Novacq™ in practical and Commercial feeds improved growth and efficiency of PL12 and juvenile shrimp suggesting its validity as a useful feed additive in the nutrition of white leg shrimp
Microplastics in African ecosystems: current knowledge, abundance, associated contaminants, techniques, and research needs
No full textDespite Africa ranking top in mismanaged plastic waste, there is insufficient data on the extent of microplastics and its interaction with other contaminants in its ecosystems. Microplastics pollution has been documented globally, however, specific data from the continent is crucial for accurate risk assessment and to drive policies. We critically reviewed 56 articles from 1987 to 2020 and provide an overview of the current knowledge of the abundance and distribution of microplastics and associated contaminants in African aquatic systems and organisms. Most of the studies were carried out in the marine environment and there is currently no available data on the abundance of microplastic pollution in the African terrestrial environment. We show that across all studies, 5–100% of all sampled aquatic organisms contained microplastics. Concerning high levels of microplastics were reported in fish from Egypt compared to other parts of Africa and the world. Across all persistent organic pollutants sampled in microplastics, hopanes and phthalates were present at high concentrations while sodium and zinc were high relative to other trace metals reported. The most frequently occurring plastics were polyethylene followed by polypropylene and polystyrene. We found that most of the studies relied on visual inspection (52%) > FTIR (38%) > Raman spectroscopy (5%) > Scanning electron microscopy (3%) > Differential scanning calorimetry (2%) for identifying microplastics. Major gaps in sampling and identification techniques which may have overestimated or underestimated the current levels were identified. We discuss other research priorities and recommend solutions to address these issues associated with microplastic pollution in Africa
Recent progress of advanced anode materials of lithium-ion batteries
No full textThe rapid development of electric vehicles and mobile electronic devices is the main driving force to improve advanced high-performance lithium ion batteries (LIBs). The capacity, rate performance and cycle stability of LIBs rely directly on the electrode materials. As far as the development of the advanced LIBs electrode is concerned, the improvement of anode materials is more urgent than the cathode materials. Industrial production of anode materials superior to commercial graphite still faces some challenges. This review sets out the most basic LIBs anode material design. The reaction principles and structural design of carbon materials, various transition metal oxides, silicon and germanium are summarized, and then the progress of other anode materials are analyzed. Due to the rapid development of metal organic frameworks (MOFs) in energy storage and conversion in recent years, the synthesis process and energy storage mechanism of nanostructures derived from MOF precursors are also discussed. From the perspective of novel structural design, the progress of various MOFs-derived materials for alleviating the volume expansion of anode materials is discussed. Finally, challenges for the future development of advanced anode materials for LIBs will be considered
Characterising the exposure of Australian firefighters to polycyclic aromatic hydrocarbons generated in simulated compartment fires
No full textFirefighters are exposed to a wide variety of chemicals including polycyclic aromatic hydrocarbons (PAHs) while attending fire scenes. The objective of this study was to understand the exposure of firefighters to PAHs when attending simulated compartment fires that consisted of either a diesel pan or particleboard fire. Firefighters remained in the compartment fires for 15 min while using standard gear including self contained breathing apparatus (SCBA). Firefighters were able to remove firefighting clothing and shower within 10 min of leaving the burn. Air samples were collected from inside the compartment during the fire. Twenty-six (26) firefighters participated in the study providing urine and skin wipe samples collected from the wrist and neck before and after either one of the burn types. The concentrations of PAHs were measured in skin wipes and air samples, while concentrations of monohydroxy metabolites of PAHs (OH-PAHs) were measured in urine. The concentrations of all PAHs were significantly higher (p 0.05) in the concentration of all OH-PAHs between pre-burn and post-burn. Samples from participants who attended particleboard fires, showed no significant difference (p > 0.05) between 1-hydroxypyrene (1-OH-PYR) concentrations in urine pre- and post-burn. However, median concentrations of hydroxynaphthalenes (OH-NAPs), hydroxyfluorenes (OH-FLUs) and hydroxyphenanthrenes (OH-PHEs) increased significantly from 5.2, 0.44 and 0.88 μg g creatinine pre-burn to 12, 1.4 and 1.2 μg g creatinine post-burn, respectively. This suggests that in compartment burns with high concentrations of PAHs in the smoke layer, such as those created by the particleboard fires, exposure to PAHs can be observed though urinary OH-PAH metabolites. Overall, concentrations of urinary OH-PAHs were relatively low considering the potential exposure in these burns. This suggests protective equipment in combination with rapid removal of firefighting ensembles and showering are relatively effective in controlling exposure
Utilising venom activity to infer dietary composition of the Kenyan horned viper (Bitis worthingtoni)
No full textBitis are well known for being some of the most commonly encountered and medically important snake species in all of Africa. While the majority of species possess potently anticoagulant venom, only B. worthingtoni is known to possess procoagulant venom. Although known to be the basal species within the genus, B. worthingtoni is an almost completely unstudied species with even basic dietary information lacking. This study investigated various aspects of the unique procoagulant effects of B. worthingtoni venom. Coagulation assays determined the primary procoagulant effect to be driven by Factor X activating snake venom metalloprotease toxins. In addition to acting upon the mammalian blood clotting cascade, B. worthingtoni venom was also shown to clot amphibian plasma. As previous studies have shown differences in clotting factors between amphibian and mammalian plasmas, individual enzymes in snake venoms acting on plasma clotting factors can be taxon-selective. As venoms evolve under purifying selection pressures, this suggests that the procoagulant snake venom metalloprotease toxins present in B. worthingtoni have likely been retained from a recent common ancestor shared with the related amphibian-feeding Proatheris superciliaris, and that both amphibians and mammals represent a substantial proportion of B. worthingtoni current diet. Thus, taxon-specific actions of venoms may have utility in inferring dietary composition for rare or difficult to study species. An important caveat is that to validate this hypothesis field studies investigating the dietary ecology of B. worthingtoni must be conducted, as well as further investigations of its venom composition to reconstruct the molecular evolutionary history of the toxins present
Toughening of natural rubber nanocomposites by the incorporation of nanoscale lignin combined with an industrially relevant leaching process
No full textStrong and tough nanocomposite materials based on natural rubber (NR) latex demonstrate increasing potential to be used in advanced engineering applications and personal care products. Among many approaches for improving the toughness of NR-based products, the use of renewable and bio-based nanofillers is persuaded by environmental and economic trends. In this study, we report the preparation and incorporation of nanoscale organosolv lignin (OSL) particles in NR latex to improve its mechanical properties. We showed that the tensile strength, toughness, and Shore hardness of NR films reinforced with 5 wt % nanoscale OSL were improved by 39 %, 53 % and 12 %, respectively, while retaining high elongation at break (∼1800 %). This substantially improved mechanical property profile can be attributed to the enhanced nanoscale dispersion of OSL and the associated favourable interfacial adhesion of OSL with the NR matrix. Furthermore, the impact of an industrially applicable leaching process on the toughness and thermo-oxidative stability of rubber films is also discussed. For an instance, after the leaching process, the tensile strength, elongation, and toughness of 1 wt % OSL/NR were increased by 27 %, 9%, and 32 %, respectively
Investigating the impact of perceived nonprofit sponsorship engagement on prosocial behavior
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Exploring Janus MoSSe monolayer as a workable media for SOF6 decompositions sensing based on DFT calculations
No full textIn modern electric systems, partial discharge (PD) or local overheating happens inevitably, leading to the SF insulated switchgears decomposition into several types of gas molecules. Thus, online monitoring these decomposition gases is considered as a promising way to detect PD to timely alarm and guarantee the safety operation of power equipments. Here, we propose recently synthesized Janus monolayer MoSSe as a superior gas sensing material by investigating the adsorption behaviors of SF decompositions, including HS, SO, SOF and SOF on Janus surfaces by first-principles calculations. The adsorption patten of SF decompositions on MoSSe monolayer is: SO > SOF > HS > SOF, in which all the absorptions exhibit physisorption. Besides, the binding strengths of the molecules adsorbed on S-layer are weaker than these on Se-layer due to the presence of out-of-plane polarization in Janus monolayer. While the adsorption strengths can be slightly enhanced by intrinsic S/Se vacancies or strain-driven of MoSSe monolayer. Importantly, the adsorption intensity can be modulated effectively by the applied electric fields. Furthermore, the response and desorption time of gas molecules on MoSSe monolayer are evaluated. With high gas sensitivity and selectivity towards SF decompositions, Janus MoSSe monolayer is demonstrated to be a promising material to be used in gas-insulated switch-gear (GIS) and constructed ultrahigh sensitivity nanodevices
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