Performance Evaluation of PDMS or PEBAX-Coated Polyetherimide Membrane for Oxygen/Nitrogen Separation

Since the industrial revolution era, the Earth was suffering from serious air pollution. Millions of people are now suffering from indoor air pollution related diseases, especially in the industrialized countries such as China. One method to improve the indoor air quality is by oxygen enhancement. Membrane technology has been a key research over the past decades due to its low energy usage, minimum chemical consumption as well as small setting up layout. In this study, polyetherimide (PEI) membranes coated with polydimethylsiloxane (PDMS) or poly(ether block amide) (PEBAX) at different concentration (1, 3 or 5 wt%) were used to evaluate the oxygen/nitrogen gas separation. Prior to the gas permeation study, the membranes were characterized using scanning electron microscope (SEM) for morphology observation and surface elemental analysis by energy dispersive X-ray spectroscope (EDX). The morphology of the self-fabricated PEI membranes is composed of a thin and dense structure supported by the finger-like structure. The results obtained from oxygen/nitrogen separation studies shows membrane coated with 3 wt% PDMS yield a good separation results, exhibiting an improvement of oxygen and nitrogen permeance by 28.2% and 24.9%, selectivity by 10.4% (up to 5.08) relative to the base PEI membrane. Meanwhile, the 3 wt% PEBAX-coated PEI membrane only achieved selectivity of 3.56. The PDMS-coated PEI membrane yield a better separation performance attributed to the fact that PDMS coating on the hollow fiber membrane improve the surface morphology by reducing the defects.

Effect additional pH on separation extraction gadolinium from terbium and europium with Di-2-(ethylhexcyl)phosphate acid

Rare earth elements are strategic materials, difficult to obtain, and have wide uses. Currently, it is still difficult to separate and refine REE’s because it has similar physical and chemical properties. Solvent extraction is most successful method used for the separation of REE’s. Di-2-ethylhexyl phosphoric acid has been widely used in industry for the separation and of REE’s. Purpose of this study is effect of pH on basic parameters extraction which include distribution coefficient, extraction efficiency and separation factor in extraction gadolinium, terbium and europium through complex with D2EHPA. Determination effect pH is a parameter determined in process extracting standard solutions gadolinium, terbium and europium using D2EHPA with n hexane. Basic parameters in extraction gadolinium, terbium and europium with D2EHPA at pH 4 are as follows KdGd = 89.90; αGd/Tb = 5.63, Gd/Eu = 1.83; %E = 98.90. KdTb = 15.94; αTb/Gd = 0.17; Tb/Eu = 0.32; % E = 94.10; KdEu = 1.40; αEu/Gd = 0.01, Eu/Tb = 0.08; %E = 98.29. From these valuesit can be concluded that gadolinium, can be separated from terbium and europium by the solvent extraction method by forming complex D2EHPA with best separation results obtained at pH 4.

Impacts of Surface Hydrophilicity of Carboxylated Polyethersulfone Supports on the Characteristics and Permselectivity of PA-TFC Nanofiltration Membranes

Our current study experimentally evaluates the impacts of surface hydrophilicity of supports on the properties of polyamide (PA) thin-film composite (TFC) nanofiltration (NF) membranes. A series of “carboxylated polyethersulfone” (CPES) copolymers with an increasing “molar ratio” (MR) of carboxyl units were used to prepare supports with diverse surface hydrophilicities by the classical nonsolvent-induced phase separation (NIPS) method. Then, the PA-TFC NF membranes were finely fabricated atop these supports by conventional interfacial polymerization (IP) reactions. The linkages between the surface hydrophilicity of the supports and the characteristics of the interfacially polymerized PA layers as well as the permselectivity of NF membranes were investigated systematically. The morphological details of the NF membranes indicate that the growth of PA layers can be adjusted through increasing the surface hydrophilicity of the supports. Moreover, the separation results reveal that the NF membrane fabricated on the relatively hydrophobic support exhibits lower permeability (7.04 L·m−2·h−1·bar−1) and higher selectivity (89.94%) than those of the ones prepared on the hydrophilic supports (14.64~18.99 L·m−2·h−1·bar−1 and 66.98~73.48%). A three-stage conceptual scenario is proposed to illustrate the formation mechanism of the PA layer in NF membranes, which is due to the variation of surface hydrophilicity of the supports. The overall findings specify how the surface hydrophilicity of the supports influences the formation of PA layers, which ultimately defines the separation performances of the corresponding NF membranes.

The Influence of Annealing Atmosphere, Blending Ratio, and Molecular Weight on the Phase Behavior of Blend Materials

In the study of block copolymers, many parameters need to be adjusted to obtain good phase separation results. Based on block copolymer polystyrene-b-polycarbonate and homopolymer polystyrene, the effects of the annealing atmosphere, blending ratio, and molecular weight on phase separation were studied. The results show that annealing in air can inhibit the occurrence of phase separation. In addition, snowflake patterns are formed during phase separation. The blending ratio affects the quality of the pattern. The molecular weight affects the size of the pattern, and the size increases as the molecular weight increases. In this article, the influence of process conditions and materials on phase separation was discussed, which has laid a solid foundation for the development of block copolymer self-assembly in the future.

Connection of core and tail Mediator modules restrains transcription from TFIID-dependent promoters

The Mediator coactivator complex is divided into four modules: head, middle, tail, and kinase. Deletion of the architectural subunit Med16 separates core Mediator (cMed), comprising the head, middle, and scaffold (Med14), from the tail. However, the direct global effects of tail/cMed disconnection are unclear. We find that rapid depletion of Med16 downregulates genes that require the SAGA complex for full expression, consistent with their reported tail dependence, but also moderately overactivates TFIID-dependent genes in a manner partly dependent on the separated tail, which remains associated with upstream activating sequences. Suppression of TBP dynamics via removal of the Mot1 ATPase partially restores normal transcriptional activity to Med16-depleted cells, suggesting that cMed/tail separation results in an imbalance in the levels of PIC formation at SAGA-requiring and TFIID-dependent genes. We propose that the preferential regulation of SAGA-requiring genes by tailed Mediator helps maintain a proper balance of transcription between these genes and those more dependent on TFIID.

Adsorption Equilibrium, Kinetics, Thermodynamics and Dynamic Separation of Magnesium and CalciumIons from Industrial Wastewater by New Strong Acid Cation Resin of SPVC

In the research work, the adsorption equilibrium, kinetics, thermodynamics and dynamic separation of magnesium and calcium ions from industrial wastewater by new strong acid cation resin of SPVC (sulphonated polyvinylchloride) were investigated. The sorption capacity of the studied resin was 3.78 mmol/g and 3.74 mmol/g for magnesium and calcium ions, respectively, according to Langmuir isotherm. It was found that the pseudo−first−order model was better fitted for the adsorption kinetics of magnesium and calcium ions on the resin. The dynamic separation results confirmed that the selected resin effectively separated magnesium and calcium ions from industrial wastewater in the dynamic condition. The change of the standard Gibbs free energy (G) and enthalpy (H), and entropy (S) were calculated. The obtained results confirmed that the adsorption of magnesium and calcium ions on the selected resin is endothermic.

Truss network based morphometric and meristic variations among south-western populations of Macrognathus aculeatus in Bangladesh

Aim: Landmark-based truss network system was applied to examine the morphometric and meristic differences among four different populaces of Macrognathus aculeatus namely; Dhakuriabeel, Jashore (DBJ); Arial Kha River, Madaripur (AKRM); Nabaganga River, Jhenaidah (NRJ); Kopotakkha River, Jashore (KRJ) in Bangladesh. Methodology: Completely 80 samples of M. aculeatus were collected (20 individuals from each population) for this study. Six meristic characters, 6 morphometric characters and 15 truss-based morphometric characters were measured for one-way analysis of variance (ANOVA) and Tukey-HSD post hoc test. Discriminant function analyses were also performed by using morphometric and truss-based morphometric characters to detect potential characters responsible for population separation. Results: Completely 80 samples of M. aculeatus were collected (20 individuals from each population) for this study. Six meristic characters, 6 morphometric characters and 15 truss-based morphometric characters were measured for one-way analysis of variance (ANOVA) and Tukey-HSD post hoc test. Discriminant function analyses were also performed by using morphometric and truss-based morphometric characters to detect potential characters responsible for population separation. Interpretation: The baseline information derived from the present study would be useful for appropriate conservation of M. aculeatus populations as well as for the researchers for further investigation.

DRD2, DAT1, AND COMT genotypes as moderators of the relation between maternal depressive symptoms and infant cortisol reactivity

Both maternal depression and dopamine-related genotypes have been linked to the development of the HPA axis. This thesis explored whether and how DRD2, DAT1, and (from an exploratory perspective) COMT genotypes moderate the relation between maternal depressive symptoms and infant cortisol reactivity in the context of a toy frustration challenge at 16 months and in the context of a maternal separation challenge at 17 months. Buccal cells were used for the purpose of genotyping. Maternal depressive symptoms were assessed via self-report at infant age 16 months. Candidate DRD2 and DAT1 genotypes moderated the relation between maternal depressive symptomatology and infant cortisol secretion in a diathesis-stress manner in the context of the toy frustration task, and in a differential susceptibility manner in the context of the maternal separation. Results are interpreted as indicating that the nature of gene-environment interactions is context-specific.

DRD2, DAT1, AND COMT genotypes as moderators of the relation between maternal depressive symptoms and infant cortisol reactivity

Both maternal depression and dopamine-related genotypes have been linked to the development of the HPA axis. This thesis explored whether and how DRD2, DAT1, and (from an exploratory perspective) COMT genotypes moderate the relation between maternal depressive symptoms and infant cortisol reactivity in the context of a toy frustration challenge at 16 months and in the context of a maternal separation challenge at 17 months. Buccal cells were used for the purpose of genotyping. Maternal depressive symptoms were assessed via self-report at infant age 16 months. Candidate DRD2 and DAT1 genotypes moderated the relation between maternal depressive symptomatology and infant cortisol secretion in a diathesis-stress manner in the context of the toy frustration task, and in a differential susceptibility manner in the context of the maternal separation. Results are interpreted as indicating that the nature of gene-environment interactions is context-specific.

High Reynolds investigations on the ability of the full scale e-TellTale sensor to detect flow separation on a wind turbine blade section

The complexity of the flow over a wind turbine blade makes its understanding and monitoring a challenging task, especially on operating wind turbines. The innovative e-Telltale sensor is developed for that purpose : detecting the flow separation on wind turbines blades. In this paper, high Reynolds wind tunnel tests have been performed with different configurations of full scale e-Telltale sensors and wall pressure measurements on a wind turbine blade section. A comparison between the lift curve and the e-Telltale signal was used to evaluate the ability of the sensor to detect flow separation. Results show different interesting properties of the sensor response depending on its size, position along the chord and its fitting process that could be used in real applications.