Removal of Cr (VI) from simulated electroplating wastewater by magnetite nanoparticles

زمینه و هدف: کروم به عنوان یکی از مهمترین آلاینده های محیط زیست محسوب می گردد و در غلظت های بالا در پســـاب صنایع آبکاری وجود دارد. نانو ذرات آهن مغناطیسی، با استفاده از مکانیسم های جذب سطحی، تعویض یونی و نیروهای الکترواستاتیک می تواند در کنترل و حذف فلزات سنگین از فاضلاب های صنعتی مورد استفاده قرار گیرد. هدف از انجام این تحقیق بررسی کارآیی نانو ذرات مغناطیسی در حذف کروم شش ظرفیتی (VI) از پساب های شبیه سازی شده صنایع آبکاری و پارامترهای موثر بر آن می باشد. روش بررسی: در این مطالعه تجربی نانو ذرات مگنتیت با استفاده از روش سل- ژل و با افزودن کلرور آهن دو و سه ظرفیتی در محیط مایی و تحت شرایط قلیایی تهیه گردید. سپس تاثیر عوامل موثر بر این فرآیند شامل، غلظت نانو ذره، غلظت اولیه کروم، pH محلول، سرعت اختلاط و زمان تماس، بررسی گردید. برای تعیین حجم نمونه از روش تاگوچی و تحلیل داده ها بر اساس مدل رگرسیون خطی ساده انجام شد. نمونه برداری بر مبنای پروتکل نمونه برداری انجام شد. یافته ها: یافته های این تحقیق نشان داد که در شرایط pH معادل 2، غلظت اولیه کروم ۱۰ میلی گرم بر لیتر، نانو ذرات مگنتیت سنتز شده با دوز 1 گرم بر لیتر، زمان تماس 5 دقیقه و سرعت همزن 250 دور در دقیقه، حدود 82 از کرم (VI) حذف شده بود. راندمان حذف با افزایش سرعت اختلاط افزایش معنی داری داشت (001/0

Effect of magnetic field during the liquid – solid phase transition of some thermoplastic polymers

Application of external fields on a polymer is common physical treatment for modifying the polymer properties. The field is applied on the final polymeric object or during synthesising or polymerization. In this work, the magnetic field from powerful permanent magnets was applied during the phase transition from liquid to solid phase, where the polymer chain interattraction forces are minimal. So, magnetic fields with less strength may perform valuable structural variations. It is found that magnetic field of 355 mT accelerated the spherulite growth in polyethylene glycol (PEG) films. High density polyethylene (HDPE) of zigzag chain, polypropylene (PP) of chains with side group and polystyrene (PS) as glassy polymer with ring, were magnetically treated with different field strength during their phase transition. Treated and untreated film samples were tested physically. IR- spectroscopy, X-ray diffraction, DTA, DSC and tensile stress – strain testing techniques were used in order to characterize, quantitatively, most types of the occurred variations if any. PS samples were casted by hot pressing and from dilute solution in magnetic field in order to detect the effect of solidification time on the size of the magnetic induced variations. Properties of treated HDPE showed little swinging about the untreatedvalue in the field strength up to 160 mT. PP properties showed serious variations in the same range of field strength. PS films casted from dilute solution showed stronger variations than the films casted by hot pressing of the melted PS. All data are presented in coloured graphs. Spherulites images are extracted from a video clip that is used in measuring the rate of PEG spherulite growth in magnetic field

Effect of Deposition Time on the Optical Characteristics of Chemically Deposited Nanostructure PbS Thin Films

AbstractPbS thin films are good materials for antireflection coatings and for solar thermal applications in flat-plat collectors, house heating for solar chick brooding, etc. Nanocrystalline PbS thin films were deposited on glass substrates with various deposition times using chemical bath deposition technique. The study was carried out for thicknesses in the range (500-660nm). The crystalline size of these films was studied by atomic force microscope AFM. A dense surface composed of multilayered grains of films was obtained with the crystal size around 37.67nm. The optical properties of these films have been studied and show that PbS thin films have allowed direct transition and the values of energy gap varied between (1.88-1.55eV) with increasing film thickness, The large optical band gap in the films is attributed to the quantum coefficient effect. Influences of thermal treatments under various annealing temperatures on the optical properties for some deposition films were studied

The endemic Chamaecytisus albidus is nodulated by symbiovar genistearum of Bradyrhizobium in the Moroccan Maamora Forest

Out of 54 isolates from root nodules of the Moroccan-endemic Chamaecytisus albidus plants growing in soils from the Maamora cork oak forest, 44 isolates formed nodules when used to infect their original host plant. A phenotypic analysis showed the metabolic diversity of the strains that used different carbohydrates and amino acids as sole carbon and nitrogen sources. The isolates grew on media with pH values ranging from 6 to 8. However, they did not tolerate high temperatures or drought and they did not grow on media with salt concentrations higher than 85 mM. REP-PCR fingerprinting grouped the strains into 12 clusters, of which representative strains were selected for ARDRA and rrs analyses. The rrs gene sequence analysis indicated that all 12 strains were members of the genus Bradyrhizobium and their phylogeny showed that they were grouped into two different clusters. Two strains from each group were selected for multilocus sequence analysis (MLSA) using atpD, recA, gyrB and glnII housekeeping genes. The inferred phylogenetic trees confirmed that the strains clustered into two divergent clusters. Strains CM55 and CM57 were affiliated to the B. canariense/B. lupini group, whereas strains CM61 and CM64 were regrouped within the B. cytisi/B. rifense lineage. The analysis of the nodC symbiotic gene affiliated the strains to the symbiovar genistearum. The strains were also able to nodulate Retama monosperma, Lupinus luteus and Cytisus monspessulanus, but not Phaseolus vulgaris or Glycine max. Inoculation tests with C. albidus showed that some strains could be exploited as efficient inocula that could be used to improve plant growth in the Maamora forest.The authors want to thank all the people who contributed to theachievement of this study. Financial support was obtained from‘‘Académie Hassan II des Sciences et Techniques” (Morocco). MrOmar Bouhnik received a grant from the Hassan II Academy of Science and Technology. The authors also thank the Ministerio de Economía, Industria y Competitividad (Spain) for the granting ofthe ERDF-cofinanced project AGL2017–85676R

Pharmacognostic and Acute Toxicity Study of Burkea Africana Root

Burkea africana is a plant that belongs to then family Fabaceae; it is widely spread in tropical Africa including Nigeria. It is of valuable in  ethnomedicine especially in the treatment of antidote for venomous stings and bites, cutaneous and sub cutaneous parasitic infection, convulsion and pulmonary troubles. Despite the fact that roots of Burkea africana have several medicinal properties, no standardization parameter has been  assessed. Due to lack of standard parameters, proper identification and ascertaining quality and purity in the events of adulteration has been thwarted. The objective of the study was to establish some important pharmacognostic profile and safety margin of Burkea africana root with the hope of assisting in its standardization for quality, purity and safety. Elemental analysis was carried out using acid digestion method and phytochemical composition of the plants was evaluated using standard method. Acute toxicity was achieved using Lorke method to determine the LD50. Chemomicroscopical evaluation revealed the presence of cellulose, tannins, starch, lignin, calcium oxalate, suberin, aleurone grain and mucilage with the exception of calcium carbonate. The average moisture contents, total ash, acid insoluble, water soluble ash, alcohol extractive value and water extractive values in the powdered plant material were 3.8%, 7.5%, 4.43%, 8.07%, 25.0% and 20.33% respectively. In addition, Fe, Mn, Ni, Pb, Cd and Cu were found to be within the safety limit. Phytochemicals which include alkaloids, flavonoids, saponins, tannins, carbohydrates and triterpenes were detected in both aqueous and methanolic extracts. The LD50 of Burkea africana was found to be greater than 5000 mg /kg and could be considered safe for consumption. Keywords: Elemental analysis, Burkea africana, Pharmacognostic, Phytochemica

Quality control for the first large areas of triple-GEM chambers for the CMS endcaps

The CMS Collaboration plans to equip the very forward muon system with triple-GEM detectors that can withstand the environment of the High-Luminosity LHC.This project is at the final stages of R&D and moving to production. A large area of several 100 m 2 are to be instrumented with GEM detectors which will be produced in six different sites around the world. A common construction and quality control procedure is required to ensure the performance of each detector.The quality control steps will include optical inspection,cleaning and baking of all materials and parts used to build the detector,leakage current tests of the GEM foils,high voltage tests,gas leak tests of the chambers and monitoring pressures time,gain calibration to know the optimal operation region of the detector,gain uniformity tests, and studying the efficiency,noise and tracking performance of the detectors in a cosmic stand using scintillator

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18–49, 50–69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population

RANTES/CCL5 and risk for coronary events: Results from the MONICA/KORA Augsburg case-cohort, Athero-express and CARDIoGRAM studies

Background: The chemokine RANTES (regulated on activation, normal T-cell expressed and secreted)/CCL5 is involved in the pathogenesis of cardiovascular disease in mice, whereas less is known in humans. We hypothesised that its relevance for atherosclerosis should be reflected by associations between CCL5 gene variants, RANTES serum concentrations and protein levels in atherosclerotic plaques and risk for coronary events. Methods and Findings: We conducted a case-cohort study within the population-based MONICA/KORA Augsburg studies. Baseline RANTES serum levels were measured in 363 individuals with incident coronary events and 1,908 non-cases (mean follow-up: 10.2±