Removal of 1,2-dichloroethane from industrial wastewater with membrane filtration

Background and Aims: 1,2-dichloroetane [ethylene dichloride (EDC)] is a chlorinated hydrocarbon which is widely used to produce vinyl chloride. The later is the major precursor to PVC production. Wastewater originating from EDC production is characterized by high turbidity and contains ethylene dichloride and FeCl3 particles. The aim of the present study was to investigate the treatability of EDC effluent using membrane filtration.Materials and Methods: Laboratory scale experiments were carried out on Abadan petrochemical complex wastewater (EDC unit) with various membrane filtration processes that combine microfiltration with nanofiltration. Microfiltration membrane was used as a pretreatment to remove turbidity as well as FeCl3 fine particles, which may subsequently damage nanofiltration system. The microfiltration effluent was thereafter fed to a nanofiltration membrane cell. The filtration performance was assessed through turbidity, TDS, COD and 1,2-dichloroetane removals. pH, temperature and system pressure were also controlled during the study.Results: Successful removal of turbidity (97.5%) and FeCl3 particles (98%) was achieved by microfiltration. EDC concentration in raw effluent was ranged between 2,000 to 3,000 ppm. The nanofiltration membrane cell followed by microfiltration achieved a very high 1,2-dichloroetane removal (96.7) from water. The experimental results indeed showed that the permeate was consisted mainly of water, which asserts that 1,2-dichloroetane was separated in waste phase.Conclusion: The results obtained provide further support for previous researches into this brain area and support the application of membrane technology to remove and recovery of soluble organic compounds from petrochemical wastewater.Key words: Petrochemical wastewater, 1,2-dichloroetane, Membrane filtration, Nanofiltration, Microfiltratio

Insights into the chemical diversity of selected fungi from the Tza Itzá cenote of the Yucatan peninsula

Cenotes are habitats with unique physical, chemical, and biological features. Unexplored microorganisms from these sinkholes represent a potential source of bioactive molecules. Thus, a series of cultivable fungi (Aspergillus spp. NCA257, NCA264, and NCA276, Stachybotrys sp. NCA252, and Cladosporium sp. NCA273) isolated from the cenote Tza Itzá were subjected to chemical, coculture, and metabolomic analyses. Nineteen compounds were obtained and tested for their antimicrobial potential against ESKAPE pathogens, Mycobacterium tuberculosis, and nontuberculous mycobacteria. In particular, phenylspirodrimanes from Stachybotrys sp. NCA252 showed significant activity against MRSA, MSSA, and mycobacterial strains. On the other hand, the absolute configuration of the new compound 17-deoxy-aspergillin PZ (1) isolated from Aspergillus sp. NCA276 was established via single-crystal X-ray crystallography. Also, the chemical analysis of the cocultures between Aspergillus and Cladosporium strains revealed the production of metabolites that were not present or were barely detected in the monocultures. Finally, molecular networking analysis of the LC-MS-MS/MS data for each fungus was used as a tool for the annotation of additional compounds, increasing the chemical knowledge on the corresponding fungal strains. Overall, this is the first systematic chemical study on fungi isolated from a sinkhole in Mexico

Structural diversity of Perylenequinones is driven by their redox behavior

Hypocrellins and hypomycins are two subclasses of fungal perylenequinones with unique structural, biological, and photochemical properties. With the growing interest in these naturally occurring photosensitizers, more studies were warranted to better understand the structural relationships between these two subclasses of perylenequinones. In this study, the long-postulated biosynthetic precursor (7) of class B fungal perylenequinones was isolated and characterized from a Shiraia-like sp. (strain MSX60519). Furthermore, the electrochemical and chemical redox behaviors of hypocrellins and hypomycins were investigated under aerobic and anaerobic conditions. These studies served to define the structural relationship within hypocrellins (1–3), which was further supported by X-ray crystallography, and between hypocrellins and hypomycins (4–6). Chemical reductions of hypocrellins under anaerobic conditions identified the origin of hypomycin A (4), hypomycin C (5), and hypomycin E (6), which in turn served to confirm 4 and revise the absolute configurations of 5 and 6. Hypocrellins were shown to undergo reversible reduction and reoxidation under aerobic conditions, while in an anaerobic environment and longer time scale, the fully reduced form can, to some extent, undergo an intramolecular ring closing metathesis. This may impart a means of reductive pathway for self-protection against these phototoxins and explain the chemical diversity observed in the fungal metabolites

New terpenoids from the corticioid fungus Punctularia atropurpurascens and their antimycobacterial evaluation

Chemical investigation of Punctularia atropurpurascens strain HM1 (Punctulariaceae), a corticioid isolated from a decorticated piece of Quercus bark collected in Bosque de Tlalpan, Mexico City, led to the isolation of a new drimane, 1-a-hydroxy-isodrimenine (1) and a new tetrahydroxy kauranol, 16-hydroxy-phlebia-nor-kauranol (2), together with the known N-phenylacetamide (3). Structures of all compounds were elucidated by spectroscopic and spectrometric methods, and the absolute configuration of 1 and 2 was confirmed via single-crystal X-ray crystallography. The isolated compounds showed modest antimycobacterial activity

Human motion analysis and classification using radar micro-doppler signatures

The ability to detect and analyze micro motions in human body is a crucial task in surveillance systems. Although video based systems are currently available to address this problem, but they need high computational resources and under good environmental lighting condition to capture high quality images. In this paper, a novel non-parametric method is presented to detect and calculate human gait speed while analyzing human micro motions based on radar micro-Doppler signatures to classify human motions. The analysis was applied to real data captured by 10 GHz radar from real human targets in a parking lot. Each individual was asked to perform different motions like walking, running, holding a bag while running, etc. The analysis of the gathered data revealed the human motion directions, number of steps taken per second, and whether the person is swinging arms while moving or not. Based on human motion structure and limitations, motion profile of each individual was recognizable to find the combinations between walking or running, and holding an object or swinging arms. We conclude that by adopting this method we can detect human motion profiles in radar based on micro motions of arms and legs in human body for surveillance applications in adverse weather conditions

Mutation and Efflux System are Responsible for Ciprofloxacin Resistance in Klebsiella pneumoniae

The main mechanism of quinolone resistance in Klebsiella (K) pneumoniae is caused by mutation ofporin-related proteins and efflux pumps. This study aimed to investigate the prevalence of ciprofloxacin-resistant K pneumoniae in burns patients and to understand the role of the AcrAB multidrug efflux system on minimal inhibitory concentration (MIC) of ciprofloxacin. For this reason, 52 K pneumoniae samples were collected from burns patients and evaluated for the mechanism of ciprofloxacin resistance. The results demonstrated that 40 isolates of K pneumoniae were ciprofloxacin-resistant and 35 showed the mutation on gyrA locus. By inhibition of the efflux system, the MIC yield showed a significant decrease. Therefore, it could be concluded that the high rate of mutation on the gyrA locus in combination with quinolone resistance was responsible for ciprofloxacin resistance and by inhibition of AcrA, the resistance rate showed a significant decrease in K pneumoniae isolated from burns patients

Association between biofilm production, adhesion genes and drugs resistance in different SCCmec types of methicillin resistant Staphylococcus aureus strains isolated from several major hospitals of Iran

Objective(s): The ability of bacteria to produce biofilm and adhesion makes them more resistant to antibiotics. The current study aims to evaluate the biofilm formation by Staphylococcus aureus and to determine the prevalence of adhesion genes, also their correlation with drug resistance. Materials and Methods: A total of 96 MRSA were collected from hospitals of Iran's western provinces during 2012 to 2013. The presence of ica A, B, C, D, clfA, cna, fnbA, mecA genes were determined by PCR technique. Biofilm formation was studied by microtiter plate assay, the clonal relations of the strains were examined by SCCmec and Spa typing. Results: The results demonstrated that 96 of isolates were biofilm producers. The distributions of biofilm formation between isolates were 4.2, 54.2, 35.4 as high, moderate and weak, respectivelly. The highest biofilm production was observed from blood culture isolates. All virulent genes icaA, B, C, D, clfA, cna, fnbA were observed in moderate and weak biofilm formation isolates. Among high biofilm formation isolates, icaB and cna genes were not seen. Statistical analysis showed that there was a significant correlation between ica, fnbA and the biofilm production, but there was not a significant correlation between the type of samples and drug resistance, spa type and SCCmec type with biofilm production (P>0.05). Frequency of All virulent genes in type III SCCmec was higher than other types. Conclusion: The majority of MRSA isolates were biofilm producers and blood isolates ranked as the great biofilm producer. In these isolates ica D and fnbA genes are correlated with biofilm production

Worldwide Prevalence of Colistin Resistance among Enterobacteriaceae: a Systematic Review and Meta-Analysis

Background: The aim of the present meta-analysis is to estimate the prevalence of colistin resistance among the Enterobacteriaceae family.Methods: Articles from various databases (Medline, Scopus, Web of Science, and Embase) examining colistin re-sistance among Enterobacteriaceae in human, animal, and environmental specimens were searched from 2016 to 2021 using related keywords. The Cochran's Q-test and I2 were applied to evaluate heterogeneity and a random -effects model was used to assess the pooled prevalence. The meta-regression method was applied to determine he-terogeneity among the studies.Results: Of 5,145 articles, 60 articles with a sample size of 404,856 was included. The pooled estimate for preva-lence of bacterial resistance were 9.13 (95 CI: 6.96 to 11.56; I-squared = 99.4) in total, 8.34 (95 CI: 5.87 to 11.16; I-squared = 99.3) for Klebsiella spp. subgroup and 3.44 (95 CI: 2.46 to 4.57; I-squared = 98.4) for E. coli subgroup. The pooled prevalence for human and animal settings were 9.07 (95 CI: 6.77 to 11.67; I -squared = 99.3) and 9.73 (95 CI: 484 to 16.02; I-squared = 99.4), respectively. The continent (coefficient: 3.51; 95 CI: 0.08 to 6.94, p: 0.045) and bacterial type (coefficient: 0.03; 95 CI: 0.01 to 0.05 p: 0.042) had signi-ficant effects on heterogeneity among studies.Conclusion: The results of this study showed that the prevalence of colistin resistance in Enterobacteriaceae was similar between animals and humans, with the highest colistin resistance found in Klebsiella strains