Properties of Concrete Containing Rubber Aggregate Derived From Discarded Tires

This study carried out the experiment to evaluate the effects of different contents and sizes of rubber particles derived from discarded tires used for replacing fine and coarse natural aggregates, on the workability of fresh rubberized concrete and the compressive and flexural strengths of hardened rubberized concrete. The study results showed that the workability of fresh rubberized concrete was improved when replacing natural fine aggregate (sand) with fine rubber particles (2.5-5 mm) at the replacing proportions of 30-50% by volume, and when replacing natural coarse aggregate (crushed stone) with coarse rubber particles (5-20 mm) at the replacing proportions of 10-30% by volume. With respect to the mechanical properties of hardened rubberized concrete, a larger reduction in the compressive and flexural strengths was generally found when the replacing proportions increased and when coarse aggregate rather than fine aggregate was replaced by rubber particles at all replacing proportions (10-50%). However, the study results also indicated that using fine rubber particles for replacing fine natural aggregate at the low replacing proportion (up to 10%) might not cause the significant effect on the compressive and flexural strength of rubberized concrete

Expression of the recombinant enterocin E-760 in Pichia pastoris X33 and its antimicrobial activity towards Listeria monocytogenes

Bioactive compounds such as bacteriocins have become potent and promising alternatives to chemical food preservatives for extending food shelf-life and eliminating food loss from microbial spoilage. Enterocin E-760 is a specific bacterocin belonging to class II that possesses broad spectrum antibacterial activity against both Gram-negative and Gram-positive bacteria. In this study, the enterocin E-760 gene was fused to a His-tag and cloned into the expression vector, pPICzαA, and transformed into Escherichia coli DH5α cells. The recombinant plasmid was isolated, linearised and transformed into competent Pichia pastoris X33 cells using electroporation. The Pichia transformants were determined using PCR and expressed under methanol induction with the highest antibacterial activity of culture supernatants reaching 40 AU/mL. Enterocin E-760 exhibited a molecular weight of approximately 5.5 kDa and was detected directly on a Tricine SDS-PAGE gel containing Listeria monocytogenes ATCC 35152 after ethanol precipitation at a concentration ranging from 30% to 70%. This study represented the initial stages of research into using enterocin as a biopreservative in food processing

The release of wastewater contaminants in the Arctic : a case study from Cambridge Bay, Nunavut, Canada

The treatment of municipal wastewater in the Arctic is challenging due to a variety of financial, operational, climatic and technical issues. To better understand the efficacy of current wastewater treatment in this region and the hazard posed to receiving waters, we assessed the occurrence of contaminants (i.e., pharmaceuticals, antibiotic resistance genes and nutrients) as they moved through a lagoon-based treatment system in Cambridge Bay in Nunavut, Canada. Wastewater treatment in this community is performed by the use of a lagoon-tundra wetland system that is discharged into the marine environment and is representative of current common practices throughout the region. In 2014, samples were collected before and during lagoon discharge from two locations in the main lagoon, one location downstream from the lagoon effluent and three locations offshore. Grab samples were collected to measure nutrients (e.g. total nitrogen and phosphorus) and the presence of antibiotic resistance gene-bearing microbes, and Polar Organic Chemical Integrative Samplers (POCIS) were deployed to collect passively organic contaminants in all locations. A total of six pharmaceuticals were detected from a screen of twenty-eight analytes during the study: atenolol, carbamazepine, clarithromycin, metoprolol, sulfamethoxazole and trimethoprim. The greatest concentrations of nutrients, antibiotic resistance genes (ARGs) and pharmaceuticals were found in sampling locations within the treatment lagoon. Offshore of the release point, we observed limited to no detection of pharmaceuticals and ARGs and no change in total nitrogen and phosphorus from pre-release. We conclude that the current concentrations of monitored pharmaceuticals do not pose a significant hazard at this time to aquatic organisms in Cambridge Bay

Current-Use Pesticides in New Zealand Streams: Comparing Results From Grab Samples and Three Types of Passive Samplers

New Zealand uses more than a ton of pesticides each year; many of these are mobile, relatively persistent, and can make their way into waterways. While considerable effort goes into monitoring nutrients in agricultural streams and programs exist to monitor pesticides in groundwater, very little is known about pesticide detection frequencies, concentrations, or their potential impacts in New Zealand streams. We used the ‘Polar Organic Chemical Integrative Sampler’ (POCIS) approach and grab water sampling to survey pesticide concentrations in 36 agricultural streams in Waikato, Canterbury, Otago and Southland during a period of stable stream flows in Austral summer 2017/18. We employed a new approach for calculating site-specific POCIS sampling rates. We also tested two novel passive samplers designed to reduce the effects of hydrodynamic conditions on sampling rates: the ‘Organic-Diffusive Gradients in Thin Films’ (o-DGT) aquatic passive sampler and microporous polyethylene tubes (MPTs) filled with Strata-X sorbent. Multiple pesticides were found at most sites; two or more were detected at 78% of sites, three or more at 69% of sites, and four or more at 39% of sites. Chlorpyrifos concentrations were the highest, with a maximum concentration of 180 ng/L. Concentrations of the other pesticides were generally below 20 ng/L. Mean concentrations of individual pesticides were not correlated with in-stream nutrient concentrations. The majority of pesticides were detected most frequently in POCIS, presumably due to its higher sampling rate and the relatively low concentrations of these pesticides. In contrast, chlorpyrifos was most frequently detected in grab samples. Chlorpyrifos concentrations at two sites were above the 21-day chronic ‘No Observable Effect Concentration’ (NOEC) values for fish and another two sites had concentrations greater than 50% of the NOEC. Otherwise, concentrations were well-below NOEC values, but close to the New Zealand Environmental Exposure Limits in several cases

Technical efficiency of smallholder banana production: a case study in Viet Nam

Bananas are considered one of the leading trading crops due to their high demand all over the globe. Since the increasing demand leads to the expansion of global import, the existing literature is in dire need of updating, especially from the producing economies that fall in the category of developing nations. The study, thus, intends to estimate the critical efficiency of said area. Along with it, the study aims to determine the elements of banana production in the context of Vietnam using a stochastic frontier approach and technical efficiency technique. The sample of the study is the province of Vietnam named Hung Yen, and it made sure to collect the data from 160 farmers in 2022. Results of the study reveal that the farmers' technical efficiency fluctuates between the range of 89.68- 97.81%. However, the average technical efficiency of banana farmers was reported to be 95.92%. From the result, it is gauged that factors such as potassium, manure, distance, capital, and training showed positive signs at a 0.01 significance level. Also, the education and area coefficient show a positive sign at a 0.05 significance level. Finally, distance and district variables, which were the dummy variable, show a negative sign at 0.01 and 0.05 significance levels, respectively.Hoang Van Hung (Hung Yen University of Technology and Education (UTEHY)), Nguyen Van Huong (Hung Yen University of Technology and Education (UTEHY)), Le Thi Thuong (Hung Yen University of Technology and Education (UTEHY)), Thai Thi Kim Oanh (Vinh University (VU)), Nguyen Van Chuong (University of Financial – Business Administration (UFBA)), Nguyen Cong Tiep (Viet Nam National University of Agriculture (VNUA)), Thai Van Ha (Ha Noi University of Business and Technology (HUBT)), Nguyen Thi Luong (Can Tho University (CTU))Includes bibliographical references