Comparing the Performance of Organic Solvent Nanofiltration Membranes in Non-Polar Solvents

Organic solvent nanofiltration (OSN) is gradually expanding from academic research to industrial implementation. The need for membranes with low and sharp molecular weight cutoffs that are able to operate under aggressive OSN conditions is increasing. However, the lack of comparable and uniform performance data frustrates the screening and membrane selection for processes. Here, a collaboration is presented between several academic and industrial partners analyzing the separation performance of 10 different membranes using three model process mixtures. Membrane materials range from classic polymeric and thin film composites (TFCs) to hybrid ceramic types. The model solutions were chosen to mimic cases relevant to today's industrial use: relatively low molar mass solutes (330–550 Da) in n-heptane, toluene, and anisole.     

Multiple responses analysis and modeling of Fenton process for treatment of high strength landfill leachate

Landfill leachate is one of the most recalcitrant wastes for biotreatment and can be considered a potential source of contamination to surface and groundwater ecosystems. In the present study, Fenton oxidation was employed for degradation of stabilized landfill leachate. Response surface methodology was applied to analyze, model and optimize the process parameters, i.e. pH and reaction time as well as the initial concentrations of hydrogen peroxide and ferrous ion. Analysis of variance showed that good coefficients of determination were obtained (R2 > 0.99), thus ensuring satisfactory agreement of the second-order regression model with the experimental data. The results indicated that, pH and its quadratic effects were the main factors influencing Fenton oxidation. Furthermore, antagonistic effects between pH and other variables were observed. The optimum H2O2 concentration, Fe(II) concentration, pH and reaction time were 0.033 mol/L, 0.011 mol/L, 3 and 145 min, respectively, with 58.3% COD, 79.0% color and 82.1% iron removals.     

Enzymatic synthesis of sugar esters and their potential as surface-active stabilizers of coconut milk emulsions

Sugar esters are compounds with surfactant properties (biosurfactants), i.e., capable of reducing the surface tension and promote the emulsification of immiscible liquids. On the other hand, as with all emulsions, coconut milk is not physically stable and is prone to phase separation. Therefore, the aim of this work was to evaluate the synthesis of fructose, sucrose and lactose esters from the corresponding sugars using Candida antarctica type B lipase immobilized in two different supports, namely acrylic resin and chitosan, and evaluate its application in the stabilization of coconut milk emulsions. The enzyme immobilized on chitosan showed the highest yield of lactose ester production (84.1%). Additionally, the production of fructose ester was found to be higher for the enzyme immobilized on the acrylic resin support (74.3%) as compared with the one immobilized on chitosan (70.1%). The same trend was observed for the sucrose ester, although with lower percentage yields. Sugar esters were then added to samples of fresh coconut milk and characterized according to their surface tension, emulsification index and particle size distribution. Although the microscopic analysis showed similar results for all sugar esters, results indicated lactose ester as the best biosurfactant, with a surface tension of 38.0 N/m and an emulsification index of 54.1%, when used in a ratio of 1:10 (biosurfactant:coconut milk, v/v) for 48 h experiments.     

A supplemental computer-assisted intervention programme to prevent early reading difficulties in Spanish learners: A stratified random control trial

Difficulties in implementing effective instruction for at-risk students arise from two challenges: the transfer of evidence-based knowledge and the lack of economic resources. Computer-assisted programmes offer a suitable solution, providing quality instruction using low-cost resources. Thirty-two first-grade students with early learning difficulties were identified and paired based on at least three of the pre-intervention reading measures (reading efficiency of monosyllabic and disyllabic items, words, pseudowords and text reading speed). Each pair was assigned to one of two different intervention programmes: a computer-assisted intervention programme (CAIP) focused on syllables or the programme provided by the Spanish State School Assistance Services (SSAS). Every week, the CAIP participants received in pairs four 15-min training sessions on syllable decoding plus one 30-min group comprehension session. The CAIP was delivered by trainee students. The SSAS programme typically consisted of a 1-hr individual or in small groups sessions per week delivered by trained practitioners. Both programmes were administered for 11 weeks. The CAIP intervention showed better results than the SSAS intervention for both decoding and comprehension, with moderate to large effect sizes.     

Changes in Coupled Vibration Frequencies and Modes of Wall-Cavity Systems Induced by Stiffness Variation in the Structure

Problems of fluid structure interactions are governed by a set of fundamental parameters. This work aims at showing through simple examples the changes in natural vibration frequencies and mode shapes for wall-cavity systems when the structural rigidity is modified. Numerical results are constructed using ANSYS software with triangular finite elements for both the fluid （2D acoustic elements） and the solid （plane stress） domains. These former results are compared to proposed analytical expressions, showing an alternative benchmark tool for the analyst. Very rigid wall structures imply in frequencies and mode shapes almost identical to those achieved for an acoustic cavity with Neumann boundary condition at the interface. In this case, the wall behaves as rigid and fluid-structure system mode shapes are similar to those achieved for the uncoupled reservoir case.     

Sulfonated Beet Pulp as Solid Catalyst in One-Step Esterification of Industrial Palm Fatty Acid Distillate

In this research a new heterogeneous catalyst has been prepared for biodiesel production. The catalyst was prepared by sulfonating industrial sugar waste. Unlike homogeneous catalysts, which require further purification and separation from the biodiesel production reaction media, this inexpensive synthetic catalyst does not need to go through an additional separation process. This advantage consequently minimizes the total application costs. The catalyst was prepared by partially carbonizing sugar beet pulp at 400 °C. The carbonization product was then sulfonated with concentrated H₂SO₄ vapor in order to produce a solid catalyst. The prepared catalyst was used in the esterification reaction between palm fatty acid distillate (PFAD) and methanol. The effects of the temperature, methanol/PFAD ratio, reaction time and catalyst dosage on the efficiency of the production were individually investigated. The optimum biodiesel production occurred at 85 °C, a reaction time of 300 min, catalyst dosage of 3 g and methanol/PFAD ratio of 5:1 (mol/mol), lowering the acid value from 198 to 13.1 (mg KOH/g oil) or the equivalent, with a fatty acid methyl ester yield of around 92 %. The results suggest that the synthesized inexpensive catalyst is useful for biodiesel production from PFAD.     

Comparing Al-SBA-15 Support and Pt/Al-SBA-15 Catalyst: Changes in Al Speciation and Acidic Properties Induced by the Introduction of Pt via Aqueous Medium

Differences between the acidic properties of silicoaluminic Pt-containing catalysts and those assessed on their parent supports have been reported in the literature and attributed to the presence of the metal nanoparticles and to their influence on the acid sites. It is shown here that for mesoporous materials containing various types of Al species, an alternative explanation can be proposed. ²⁷Al NMR spectroscopy, FTIR of adsorbed CO and probe catalytic tests suggest the redistribution of aluminium atoms upon contact of the parent support with the aqueous solution containing the Pt precursor. Upon contact with water and thermal treatment, strong and mild Brønsted sites (Si–O(H)–Al) transform into strong Lewis sites (isolated tetracoordinated Al atoms). As a consequence, it may not be straightforward to deduce the acidic properties of metal-containing catalysts supported on Al-containing mesoporous materials from those of the bare support, because the surface species may differ significantly.     

Effects of silymarin on biochemical and oxidative stress markers in end‐stage renal disease patients undergoing peritoneal dialysis

Introduction End‐stage renal disease (ESRD) patients especially those undergoing dialysis are vulnerable to several complications, in particular those related to oxidative stress. Silymarin is an herbal medicine commonly used as an antioxidant in different pathologies. Methods To evaluate the effect of silymarin on biochemical and oxidative stress markers, 50 ESRD patients undergoing peritoneal dialysis were randomly divided into two groups of silymarin (n = 28) and control (n = 22) and received silymarin (140 mg every 8 hours) or placebo for 2 months, respectively. Ferric reducing antioxidant power and total 8‐iso‐prostaglandin F_2α were measured in plasma, while catalase enzyme activity was measured in erythrocytes of both groups before and after treatment. Findings Ferric reducing antioxidant power values after treatment were significantly decreased in silymarin group compared to before treatment values (17.2 ± 2.9 and 15.9 ± 3.1 µM equivalent of quercetin/dL, respectively, P < 0.05). Conversely, catalase levels were increased 17.3% after silymarin consumption, while it was decreased 9.1% in control group. Further, hemoglobin (from 10.94 ± 2.17 to 11.54 ± 2.03 g/dL, P < 0.05) and albumin levels (from 3.48 ± 0.67 to 3.61 ± 0.53 g/dL, P < 0.05) were significantly increased after silymarin administration. Discussion It is concluded that silymarin could be regarded as a supplementary therapy for ESRD patients undergoing peritoneal dialysis in order to reduce complications.     

Synthesis and optical properties of dyes encapsulated in gold hollow nanoshells

Gold nanomaterials are promising objects for applications in optics and medicine because of their unique properties related to the Surface Plasmon Resonances (SPR) phenomena. It is possible to tune these properties with the control of the size and shape of the nanomaterials. Gold hollow spheres nanomaterials are an interesting concept for encapsulation of either dyes or drugs. The study of their properties and their behavior in a bio-environment still remains scarce and some phenomena are still to be explained in particular regarding local field enhancement effect or quenching of their photophysical properties. In this work we describe a process allowing inclusion of optical dyes in gold nanoshells and evaluate the optical properties.