Influence of the measurement medium and matrix modifiers on the determination of silicon in waters by graphite furnace atomic absorption spectrometry

An electrothermal atomic absorption (ETAAS) method has been developedfor the direct determination of Si in natural waters. Measurements were carried out on previously alkalinized samples and using a mixture of Pd and Mg(NO3)2 as matrix modifier, with an ashing temperature of 1400 oC and an atomization temperature of 2400 oC. Transversally heated pyrolitically graphite tubes, equipped with Lfvov platform and Zeeman effect correction, was employed in this study. A limit of detection of 2.6 ƒÊg/L Si was obtainedand accuracy was evaluated by analyzing two Standard Reference Material at different concentration levels, a good agreement (<5%) was obtained. This developed procedure was demonstrated of the need of using an alkaline medium for accurate Si determination by ETAAS

Influence of the measurement medium and matrix modifiers on the determination of silicon in waters by graphite furnace atomic absorption spectrometry.

An electrothermal atomic absorption (ETAAS) method has been developed for the direct determination of Si in natural waters. Measurements were carried out on previously alkalinized samples and using a mixture of Pd and Mg(NO3)2 as matrix modifier,with an ashing temperature of 1400 \ub0C and an atomization temperature of 2400 \ub0C. Transversally heated pyrolitically graphite tubes, equipped with L\u2019vov platform and Zeeman effect correction, was employed in this study. A limit of detection of 2.6 \u3bcg/L Si was obtained and accuracy was evaluated by analyzing two Standard Reference Material at different concentration levels, a good agreement (<5%) was obtained. This developed procedure was demonstrated of the need of using an alkaline medium for accurate Si determination by ETAAS. \ua9 JASE

Étude de la Performance du Dispositif de Traitement des Eaux UsÉes par Boues ActivÉes de la ville d’Al- Hoceima, Maroc

Morocco has taken over the desire to ensure sustainable development and to promote the treatment of domestic and industrial wastewater. In this context, several sewage treatment plants were created, in order to protect the environment from direct discharges of wastewater, and to hope for the reuse of treated wastewater. The use of Activated sludge process in treating the wastewater has been the solution to many problems. In order to evaluate the performance of wastewater treatment plant of the city of Al-Hoceima (North of Morocco). We studied the physico-chemical and bacteriological parameters; we carried out a series of measures such as: temperature, pH and conductivity, the biochemical oxygen demand BOD5, the chemical oxygen demands COD, fecal coliforms (FC) and total coliforms (TC). Measurement of the BOD5, COD and TSS yields values give respectively 96%, 95% and 85%. The tests showed that the treated water can be obtained with a quality complying with the agricultural reuse

Impact Des Facteurs De Pollution Sur La Qualite Des Eaux De La Zone Aval De La Vallee De L’oued Nekor (Al-Hoceima, Maroc)

Water is a precious and essential natural resource for multiple uses. Its use for food or hygiene requires excellent physicochemical and microbiological quality. To assess the quality of well water for human consumption in the Al Hoceima region which is located in North of Morocco, a physico-chemical and bacteriological control was carried out on the basis of 10 water samples from wells in this area. The analyzes were performed on these samples by measuring the following physic-chemical parameters: temperature, pH, electric conductivity (EC), chloride (Cl -),dissolved oxygen, nitrate (NO3 -), and possibly seeking unwanted bacteria (total bacteria, total coliforms, fecal coliforms, fecal streptococci). The samples were analyzed systematically to measure all the physicochemical indicators of pollution. Correlation between pollution parameters were conducted to give a reponse element on the main causes pollution. The results performed analysis, revealed a pollution of an agricultural origin. This is confirmed by the maximum levels of chlorides, which exceed 2640 mg/l, thereby explaining the high conductivity levels (4800μs/cm). In addition 14% of analyzed wells have nitre levels 50mg/l nitrate pollution a not alarming. However, if a pollution of agricultural origin is mentioned, the lithological contribution can not be neglected on the results obtained

Use of Natural Safiot Clay for the Removal of Chemical Substances From Aqueous Solutions by Adsorption: A Combined Experimental and Theoretical Study

The main objective of this work was to investigate the potential of Natural Safiot Clay (NSC), as an adsorbent for the removal of two cationic dyes such as Basic Blue 9 (BB9) and Basic Yellow 28 (BY28) from single and binary systems in aqueous solutions. For this, the effects of three factors controlling the adsorption process, such as initial dye concentration, adsorbent dose, and initial pH on the adsorption extent, were investigated and examined. The natural safiot clay was characterized using the following technique: energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), DRX, and Fourier transform infrared (FT-IR) and pH of the point of zero charge (pHZPC). Energy-dispersive X-ray spectroscopy results indicate high percentages of Silica and Alumina. FT-IR spectrum identified kaolinite as the major mineral phase in the presence of quartz, calcite, and dolomite. The quantum theoretical study confirms the experimental results, through the study of the global and local reactivity and the electrophilicity power of the dyes. The electrophilicity power of dyes affects the removal efficiency. The theoretical study proves that BB9 (ω = 6.178) is more electrophilic than BY28 (ω = 2.480) and more interactions with surface sites. The results of the molecular dynamics simulation indicate that the dyes are adsorbed parallel to the surface of natural Safi clay (kaolinite), implying the strong interaction with the kaolinite atoms. All the results of quantum chemistry calculations and simulations of molecular dynamics are in perfect agreement with the results of the experimental study

Application of Particle Swarm Optimization for Optimizing the Process Parameters in Turning of PEEK CF30Composites

This work deals with optimization of multiple characteristics in CNC turning of reinforced Poly Ether Ether Ketone (PEEK CF30) with TiN coated tools under dry condition. The considered criteria included specific cutting pressure, machining force and cutting power. Three controllable factors of the turning process consisting of cutting speed, depth of cut and feed rate were incorporated. Taguchi design of experiments method was used to arrange the experimentation task. The developed response surface models were then employed with particle swarm optimization (PSO) to optimize the cutting conditions. PSO program gives the minimum values of the considered criteria and the corresponding optimal cutting conditions

Microbiome alteration Via Fecal Microbiota Transplantation Is Effective For Refractory Immune Checkpoint inhibitor-induced Colitis

Immune checkpoint inhibitors (ICIs) target advanced malignancies with high efficacy but also predispose patients to immune-related adverse events like immune-mediated colitis (IMC). Given the association between gut bacteria with response to ICI therapy and subsequent IMC, fecal microbiota transplantation (FMT) represents a feasible way to manipulate microbial composition in patients, with a potential benefit for IMC. Here, we present a large case series of 12 patients with refractory IMC who underwent FMT from healthy donors as salvage therapy. All 12 patients had grade 3 or 4 ICI-related diarrhea or colitis that failed to respond to standard first-line (corticosteroids) and second-line immunosuppression (infliximab or vedolizumab). Ten patients (83%) achieved symptom improvement after FMT, and three patients (25%) required repeat FMT, two of whom had no subsequent response. At the end of the study, 92% achieved IMC clinical remission. 1