Insights into the reinforcement and mechanism of silicone mold rubber co-modified with WCB and MMQ resin

The exploitation of condensation room-temperature vulcanized silicone rubber (C-RTV) with excellent mechanical properties and thermal stability is of great practical significance in the preparation of insulation materials and rubber products with high performance. In this work, novel silicone rubber was fabricated successfully by adding white carbon black (WCB) and different percentages of methyl MQ (MMQ) silicone resin to C-RTV silicone mold rubbers (C-RTV/WMMQ). The mechanical properties, dimensional thermal stabilities, and thermal decomposing temperatures of the as-prepared samples were investigated in detail. Compared to the primitive C-RTV, the tensile strength of the sample with the WCB adding an amount of 15% increased from 0.44 MPa to 3.9 MPa. When the 1% MMQ was introduced, the tensile strength further increased to 4.4 MPa, suggesting a 12.8% reinforcement rate in addition to the improvements in the dimensional thermal stabilities and decomposing temperature. Based on the experimental results, a feasible synergistic effect and compatibility mechanism was proposed that hydrogen bond formed on the interface between MMQ resin and C-RTV in addition to the rigid structure of WCB, and thus led to a dense crosslinking network structure in the polymer matrix

Construction of Magnetic Composite Bacterial Carrier and Application in 17<i>β</i>-Estradiol Degradation

Estrogen contamination is widespread and microbial degradation is a promising removal method; however, unfavorable environments can hinder microbial function. In this study, a natural estrogen 17β-estradiol (E2) was introduced as a degradation target, and a new combination of bacterial carrier was investigated. We found the best combination of polyvinyl alcohol (PVA) and sodium alginate (SA) was 4% total concentration, PVA:SA = 5:5, with nano-Fe3O4 at 2%, and maltose and glycine added to promote degradation, for which the optimal concentrations were 5 g·L−1 and 10 g·L−1, respectively. Based on the above exploration, the bacterial carrier was made, and the degradation efficiency of the immobilized bacteria reached 92.3% in 5 days. The immobilized bacteria were reused for three cycles, and the degradation efficiency of each round could exceed 94%. Immobilization showed advantages at pH 5, pH 11, 10 °C, 40 °C, and 40 g·L−1 NaCl, and the degradation efficiency of the immobilized bacteria was higher than 90%. In the wastewater, the immobilized bacteria could degrade E2 to about 1 mg·L−1 on the 5th day. This study constructed a bacterial immobilization carrier using a new combination, explored the application potential of the carrier, and provided a new choice of bacterial immobilization carrier

Lysinibacillus sp. GG242 from Cattle Slurries Degrades 17&beta;-Estradiol and Possible 2 Transformation Routes

Environmental estrogen pollution has long been a concern due to adverse effects on organisms and ecosystems. Biodegradation is a vital way to remove estrogen, a strain of Lysinibacillus sp. was isolated, numbered strain GG242. The degradation rate of 100 mg&middot;L&minus;1 17&beta;-estradiol (E2)) &gt; 95% in one week, and compared with extracellular enzymes, intracellular enzymes have stronger degradation ability. Strain GG242 can maintain a stable E2 degradation ability under different conditions (20&ndash;35 &deg;C, pH 5&ndash;11, salinity 0&ndash;40 g&middot;L&minus;1). Under appropriate conditions (30 &deg;C, pH 8, 1 g&middot;L&minus;1 NaCl), the degradation rate increased by 32.32% in one week. Based on the analysis of transformation products, inferred E2 was converted via two distinct routes. Together, this research indicates the degradation potential of strain GG242 and provides new insights into the biotransformation of E2

Monitoring consumption of common illicit drugs in Kuala Lumpur, Malaysia, by wastewater-cased epidemiology

Southeast Asian countries including Malaysia play a major role in global drug trade and abuse. Use of amphetamine-type stimulants has increased in the past decade in Malaysia. This study aimed to apply wastewater-based epidemiology for the first time in Kuala Lumpur, Malaysia, to estimate the consumption of common illicit drugs in urban population. Influent wastewater samples were collected from two wastewater treatment plants in Kuala Lumpur in the summer of 2017. Concentrations of twenty-four drug biomarkers were analyzed for estimating drug consumption. Fourteen drug residues were detected with concentrations of up to 1640 ng/L. Among the monitored illicit drugs, 3,4-methylenedioxy-methamphetamine (MDMA) or ecstasy had the highest estimated per capita consumptions. Consumption and dose of amphetamine-type stimulants (methamphetamine and MDMA) were both an order of magnitude higher than those of opioids (heroin and codeine, methadone and tramadol). Amphetamine-type stimulants were the most prevalent drugs, replacing opioids in the drug market. The prevalence trend measured by wastewater-based epidemiology data reflected the shift to amphetamine-type stimulants as reported by the Association of Southeast Asian Nations Narcotics Cooperation Center. Most of the undetected drug residues were new psychoactive substances (NPSs), suggesting a low prevalence of NPSs in the drug market