Electro-coagulation coupled Electro-floatation process: Feasible choice in Doxycycline removal from Pharmaceutical effluents

Article CC-BYInternational audienceElectrochemical treatment involving a coupled coagulation and floatation was performed in the removal of Doxycycline Hyclate (DCH) from aqueous solutions. All the experiments were carried out in an electrochemical reactor of 1.5 L which contained aluminium electrodes as cathode and anode. The removal of doxycycline hyclate (DCH) species by EC/EF was determined as a function of electrolysis time, pH, current intensity, flow rate and DCH concentration. From the observed results, it was corroborated that the DCH removal through the EC/EF process was excellent. The effective contribution from initial pH (7.03) and current intensity (5.39 mA cm-2) was very much remarkable and well apparent from flocs of good buoyancy. The removal of DCH was inversely proportional to spacing between electrodes (SBE) and circulating flow rate in the presence of the supporting NaCl electrolyte of 1 g L-1. It was also highly promoted by the addition of NaCl in comparison to NaNO3 and KCl to the electrolytic system. The compliance of four kinetic models was verified with DCH removal system. The free energy values from DKR model suggested the nature of bonding by chemical forces. Characterization by FTIR, SEM and XRD interpreted the assignments of various functional groups, surface morphology and crystalline incorporated amorphous nature, respectively of electro – generated flocs. The current efficiency and specific electrical energy consumption at optimized conditions of the EC/EF system were calculate

Influence of country and city images on students’ perception of host universities and their satisfaction with the assigned destination for their exchange programmes

ABSTRACT: This research focuses on the effect that country image, city image and university image has on students’ a priori satisfaction with the assigned destination for their international exchange programme (Bachelor and Master). In particular, this study establishes six hypotheses related to the causal relationships among the different typologies of image and their effects on students’ satisfaction with the assigned destination to study at least one semester in a host university. In order to contrast these hypotheses, a quantitative research was carried out in the Spanish city of Santander (Spain), by obtaining a sample of 245 international students who participated in an exchange programme at the University of Cantabria. The research findings are: (1) students’ satisfaction with the assigned destination is positively influenced by the university image; (2) the university image is positively influenced by the city image; and (3) the city image is positively influenced by the country image

Cdc42 controls the dilation of the exocytotic fusion pore by regulating membrane tension.

Membrane fusion underlies multiple processes, including exocytosis of hormones and neurotransmitters. Membrane fusion starts with the formation of a narrow fusion pore. Radial expansion of this pore completes the process and allows fast release of secretory compounds, but this step remains poorly understood. Here we show that inhibiting the expression of the small GTPase Cdc42 or preventing its activation with a dominant negative Cdc42 construct in human neuroendocrine cells impaired the release process by compromising fusion pore enlargement. Consequently the mode of vesicle exocytosis was shifted from full-collapse fusion to kiss-and-run. Remarkably, Cdc42-knockdown cells showed reduced membrane tension, and the artificial increase of membrane tension restored fusion pore enlargement. Moreover, inhibiting the motor protein myosin II by blebbistatin decreased membrane tension, as well as fusion pore dilation. We conclude that membrane tension is the driving force for fusion pore dilation and that Cdc42 is a key regulator of this force.journal articleresearch support, non-u.s. gov't2014 Oct 152014 08 20importe

Rab27a and Rab27b control different steps of the exosome secretion pathway

Exosomes are secreted membrane vesicles that share structural and biochemical characteristics with intraluminal vesicles of multivesicular endosomes (MVEs). Exosomes could be involved in intercellular communication and in the pathogenesis of infectious and degenerative diseases. The molecular mechanisms of exosome biogenesis and secretion are, however, poorly understood. Using an RNA interference (RNAi) screen, we identified five Rab GTPases that promote exosome secretion in HeLa cells. Among these, Rab27a and Rab27b were found to function in MVE docking at the plasma membrane. The size of MVEs was strongly increased by Rab27a silencing, whereas MVEs were redistributed towards the perinuclear region upon Rab27b silencing. Thus, the two Rab27 isoforms have different roles in the exosomal pathway. In addition, silencing two known Rab27 effectors, Slp4 (also known as SYTL4, synaptotagmin-like 4) and Slac2b (also known as EXPH5, exophilin 5), inhibited exosome secretion and phenocopied silencing of Rab27a and Rab27b, respectively. Our results therefore strengthen the link between MVEs and exosomes, and introduce ways of manipulating exosome secretion in vivo

Tamarind (Tamarindus indica) fruit shell carbon: A calcium-rich promising adsorbent for fluoride removal from groundwater.

International audienceTamarindus indica fruit shells (TIFSs) are naturally calcium rich compounds. They were impregnated with ammonium carbonate and then carbonized, leading to ammonium carbonate activated ACA-TIFS carbon. The resulting materials and carbon arising from virgin fruit shells V-TIFS were characterized and assayed as adsorbent for the removal of fluoride anions from groundwater. The fluoride scavenging ability of TIFS carbons was due to naturally dispersed calcium compounds. X-ray diffraction (XRD) showed that TIFS carbon contained a mixture of calcium oxalate and calcium carbonate. Batch studies on the fluoride removal efficiency of TIFS carbons with respect to contact time, pH, initial fluoride concentration, and co-ion interference were conducted. Applicability of various kinetic models (viz., pseudo-first-order, pseudo-second-order, intra-particle diffusion and Elovich) and sorption isotherms were tested for batch techniques. The fluoride removal capacity of TIFS carbons was found to be 91% and 83% at a pH of 7.05 for V-TIFS and ACA-TIFS carbons, respectively. The practical applicability of TIFS carbons using groundwater samples was approved. The fluoride removal was greater in groundwater without hydrogen carbonate ions than those containing these ions. The characterizations of fluoride unloaded and loaded TIFS carbons were done by SEM and XRD studies

Cerium dispersed in carbon (CeDC) and its adsorption behavior: A first example of tailored adsorbent for fluoride removal from drinking water

International audienceThe present study is contributed to the removal of excess fluoride in drinking water using cerium dispersed in carbon (CeDC), a hybrid sorbent which was prepared by carbonization of ammonium cerium sulfate impregnated starch. One synthesized CeDC sample with a specific surface area of 685 cm(2) g(-1), was investigated for its fluoride scavenging ability as the function of pH, fluoride concentration, temperature, co-ions and adsorbent dosage. The verification of various kinetic models viz., Pseudo I, II order; Ritchie II order; Intra-particle diffusion and Elovich gave acceptable results. The isotherm models viz., Langmuir, Freundlich, Temkin and Generalized Langmuir were also checked with the fluoride sorption process. The Langmuir sorption capacity (q(m)) was found to be 209 mg g(-1) with a high R-L value of 0.699. The maximum fluoride uptake capacity of CeDC was determined to be 52 mg g(-1) at a pH value of 8.07. The FTIR, SEM and XRD characterization studies were carried out for CeDC material. The successful regeneration of spent CeDC was performed by an alkaline washing followed by an acidic activation. This regeneration allows the use of CeDC in a cost-effective removal of fluoride anions in drinking water. (C) 2012 Elsevier B.V. All rights reserved

Influence of shaking or stirring dynamic methods in the defluoridation behavior of activated tamarind fruit shell carbon

International audienceFluoride is essential when it is present less than 0.5 mg L−1 in water but its excess presence causes dental and skeletal fluorosis. In the present work, Tamarindus indica Fruit Shells (TIFSs) were activated by ammonium carbonate and then carbonized leading to carbon abbreviated as ACA-TIFSC. This material with a BET surface area of 473 m2 g−1 was used for the defluoridation studies by shaking and stirring dynamic experiments. For the two dynamic studies, the fluoride removal efficiency of ACA-TIFSC as a function of pH, initial fluoride concentration, sorbent dose and co-ionic interference was investigated. The kinetic and isotherm models were used to interpret the nature of the fluoride sorption onto ACA-TIFSC. From the experimental results, it may be evaluated that the fluoride removal efficiency of ACA-TIFSC during stirring was greater than with the shaking dynamics. The results suggest that the active sites of the adsorbent are more easily reached by fluoride anions under stirring agitation. Characterization of ACA-TIFSC through SEM and XRD studies was done before and after the fluoride loading process. The prominent feature of ACA-TIFSC is the presence of CaCO3 compounds in the carbon matrix which is evident from the results of defluoridation studies. Groundwater samples with fluoride more than 1.5 mg L−1 were efficiently treated by ACA-TIFSC. The fluoride scavenging capacity of ACA-TIFSC was improved to a maximum of 8% and 11% in the bicarbonate-free groundwater during shaking and stirring sorption methods, respectively