Evaluation of physicochemical and biological properties of chitosan/poly (vinyl alcohol) polymer blend membranes and their correlation for Vero cell growth.

PubMed

Sharma, Parul; Mathur, Garima; Dhakate, Sanjay R; Chand, Subhash; Goswami, Navendu; Sharma, Sanjeev K; Mathur, Ashwani

2016-02-10

The blend membranes with varying weight ratios of chitosan/poly (vinyl alcohol) (CS/PVA) (1:0, 1:1, 1:2.5, 1.5:1, 1.5: 2.5) were prepared using solvent casting method and were evaluated for their potential application in single-use membrane bioreactors (MBRs). The physicochemical properties of the prepared membranes were investigated for chemical interactions (FTIR), surface morphology (SEM), water uptake, protein sorption (qe), ammonia sorption and growth kinetics of Vero cells. CS/PVA blend membrane having weight ratio of 1.5:1 had shown enhanced membrane flexibility, reduced water uptake, less protein sorption and no ammonium sorption compared to CS membrane. This blend membrane also showed comparatively enhanced higher specific growth rate (0.82/day) of Vero cells. Improved physicochemical properties and growth kinetics obtrude CS/PVA (1.5:1) as a potential surface for adhesion and proliferation with possible application in single use membrane bioreactors. Additionally, new insight explaining correlation between water holding (%) of CS/PVA (1.5:1) blend membrane and doubling time (td) of Vero cells is proposed. Copyright © 2015 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Padmaraj, O.; Satyanarayana, N., E-mail: nallanis2011@gmail.com; Venkateswarlu, M.

A novel fibrous polymer blend [(100-x) % P(VdF-co-HFP)/x % PMMA, x = 10, 20, 30, 40, 50] electrolyte membranes were prepared by electrospinning technique. Structural, thermal and surface morphology of all the compositions of electrospun polymer blend membranes were studied by using XRD, DSC & SEM. The newly developed five different compositions of polymer blend fibrous electrolyte membranes were obtained by soaking in an electrolyte solution contains 1M LiPF{sub 6} in EC: DEC (1:1,v/v). The wet-ability and conductivity of all the compositions of polymer blend electrolyte membranes are evaluated through electrolyte uptake and impedance measurements. The polymer blend [90% P(VdF-co-HFP)/10%more » PMMA] electrolyte membrane showed good wet-ability and high conductivity (1.788 × 10{sup −3} Scm{sup −1}) at room temperature.« less

FTIR, XRD and DSC studies of nanochitosan, cellulose acetate and polyethylene glycol blend ultrafiltration membranes.

PubMed

Vinodhini, P Angelin; K, Sangeetha; Thandapani, Gomathi; P N, Sudha; Jayachandran, Venkatesan; Sukumaran, Anil

2017-11-01

In the present work, a series of novel nanochitosan/cellulose acetate/polyethylene glycol (NCS/CA/PEG) blend flat sheet membranes were fabricated in different ratios (1:1:1, 1:1:2, 2:1:1, 2:1:2, 1:2:1, 2:2:1) in a polar solvent of N,N'-dimethylformamide (DMF) using the most popular phase inversion method. Nanochitosan was prepared by the ionotropic gelation method and its average particle size has been analyzed using Dynamic Light Scattering (DLS) method. The effect of blending of the three polymers was investigated using FTIR and XRD studies. FTIR results confirmed the formation of well-blended membranes and the XRD analysis revealed enhanced amorphous nature of the membrane ratio 2:1:2. DSC study was conducted to find out the thermal behavior of the blend membranes and the results clearly indicated good thermal stability and single glass transition temperature (T g ) of all the prepared membranes. Asymmetric nature and rough surface morphology was confirmed using SEM analysis. From the results it was evident that the blending of the polymers with higher concentration of nanochitosan can alter the nature of the resulting membranes to a greater extent and thus amorphous membranes were obtained with good miscibility and compatibility. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation and Characterization of Hydrophilically Modified PVDF Membranes by a Novel Nonsolvent Thermally Induced Phase Separation Method

PubMed Central

Hu, Ningen; Xiao, Tonghu; Cai, Xinhai; Ding, Lining; Fu, Yuhua; Yang, Xing

2016-01-01

In this study, a nonsolvent thermally-induced phase separation (NTIPS) method was first proposed to fabricate hydrophilically-modified poly(vinylidene fluoride) (PVDF) membranes to overcome the drawbacks of conventional thermally-induced phase separation (TIPS) and nonsolvent-induced phase separation (NIPS) methods. Hydrophilically-modified PVDF membranes were successfully prepared by blending in hydrophilic polymer polyvinyl alcohol (PVA) at 140 °C. A series of PVDF/PVA blend membranes was prepared at different total polymer concentrations and blend ratios. The morphological analysis via SEM indicated that the formation mechanism of these hydrophilically-modified membranes was a combined NIPS and TIPS process. As the total polymer concentration increased, the tensile strength of the membranes increased; meanwhile, the membrane pore size, porosity and water flux decreased. With the PVDF/PVA blend ratio increased from 10:0 to 8:2, the membrane pore size and water flux increased. The dynamic water contact angle of these membranes showed that the hydrophilic properties of PVDF/PVA blend membranes were prominently improved. The higher hydrophilicity of the membranes resulted in reduced membrane resistance and, hence, higher permeability. The total resistance Rt of the modified PVDF membranes decreased significantly as the hydrophilicity increased. The irreversible fouling related to pore blocking and adsorption fouling onto the membrane surface was minimal, indicating good antifouling properties. PMID:27869711

Preparation and Characterization of Hydrophilically Modified PVDF Membranes by a Novel Nonsolvent Thermally Induced Phase Separation Method.

PubMed

Hu, Ningen; Xiao, Tonghu; Cai, Xinhai; Ding, Lining; Fu, Yuhua; Yang, Xing

2016-11-18

In this study, a nonsolvent thermally-induced phase separation (NTIPS) method was first proposed to fabricate hydrophilically-modified poly(vinylidene fluoride) (PVDF) membranes to overcome the drawbacks of conventional thermally-induced phase separation (TIPS) and nonsolvent-induced phase separation (NIPS) methods. Hydrophilically-modified PVDF membranes were successfully prepared by blending in hydrophilic polymer polyvinyl alcohol (PVA) at 140 °C. A series of PVDF/PVA blend membranes was prepared at different total polymer concentrations and blend ratios. The morphological analysis via SEM indicated that the formation mechanism of these hydrophilically-modified membranes was a combined NIPS and TIPS process. As the total polymer concentration increased, the tensile strength of the membranes increased; meanwhile, the membrane pore size, porosity and water flux decreased. With the PVDF/PVA blend ratio increased from 10:0 to 8:2, the membrane pore size and water flux increased. The dynamic water contact angle of these membranes showed that the hydrophilic properties of PVDF/PVA blend membranes were prominently improved. The higher hydrophilicity of the membranes resulted in reduced membrane resistance and, hence, higher permeability. The total resistance R t of the modified PVDF membranes decreased significantly as the hydrophilicity increased. The irreversible fouling related to pore blocking and adsorption fouling onto the membrane surface was minimal, indicating good antifouling properties.

Autoignition study of binary blends of n- dodecane/1-methylnaphthalene and iso- cetane/1-methylnaphthalene

DOE PAGES

Kukkadapu, Goutham; Sung, Chih-Jen

2017-11-24

An experimental study on autoignition of two binary blends, n-dodecane/1-methylnaphthalene and iso-cetane/1-methylnaphthalene, has been conducted using a rapid compression machine. Specifically, the ignition delays of the stoichiometric blend+air mixtures were measured at elevated pressures of P C = 15 bar and 30 bar, compressed temperatures of T C = 626–944 K, and varying blending ratios of the constituents. For a given set of P C and T C, a nonlinear response of the blend reactivity with respect to the relative amount of the constituents was observed. Since a comprehensive chemical kinetic model for the blends investigated here is under development,more » the current ignition delay datasets serve as the needed targets for model validation. For selected conditions, ignition delay simulations were conducted to highlight and discuss the deficiencies of the literature models and the potential areas for model improvements, especially at low temperatures. In conclusion, further chemical kinetic analyses were conducted to gain understanding of the blending behavior predicted by the available model.« less

Autoignition study of binary blends of n- dodecane/1-methylnaphthalene and iso- cetane/1-methylnaphthalene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kukkadapu, Goutham; Sung, Chih-Jen

An experimental study on autoignition of two binary blends, n-dodecane/1-methylnaphthalene and iso-cetane/1-methylnaphthalene, has been conducted using a rapid compression machine. Specifically, the ignition delays of the stoichiometric blend+air mixtures were measured at elevated pressures of P C = 15 bar and 30 bar, compressed temperatures of T C = 626–944 K, and varying blending ratios of the constituents. For a given set of P C and T C, a nonlinear response of the blend reactivity with respect to the relative amount of the constituents was observed. Since a comprehensive chemical kinetic model for the blends investigated here is under development,more » the current ignition delay datasets serve as the needed targets for model validation. For selected conditions, ignition delay simulations were conducted to highlight and discuss the deficiencies of the literature models and the potential areas for model improvements, especially at low temperatures. In conclusion, further chemical kinetic analyses were conducted to gain understanding of the blending behavior predicted by the available model.« less

[Preparation and physicochemical property of carboxymethyl-chitosan/hyaluronic acid poly(vinyl alcohol) blend membrane].

PubMed

Liu, Wen; Li, Shuning; Chang, Jing; Han, Baoqin; Liu, Wanshun

2009-08-01

To prepare carboxymethyl-chitosan/hyaluronic acid/poly(vinyl alcohol) (CHP) blend membrane, evaluate its physicochemical properties and intraocular biocompatibility and to investigate its feasibility to be applied to glaucoma filtering surgery. CHP blend membrane was prepared using solution casting method after blending carboxymethyl-chitosan, HA and poly(vinyl alcohol) in a proportion of 5 : 4 : 1 (M/M). Its water absorption rate, swelling rate, permeability, and mechanical properties were detected. Subconjunctival fibroblasts separated from subconjunctival tissue of New Zealand white rabbits were cultured, and the cells at passage 4 were cultured on cell culture plate with or without the CHP blend membrane, serving as the experimental group and the control group, respectively. Effect of the CHP blend membrane on the subconjunctival fibroblasts was tested by MTT method 24, 48, and 72 hours after culture. Six New Zealand white rabbits were randomly divided into two groups (n = 3 rabbits per group), and the CHP blend membrane and SK gel were implanted into the rabbits' subconjunctival space and anterior chamber in the experimental group and the control group, respectively. Slit lamp observation and binocular reaction record were conducted 1, 3, 5, 9, 11, 20, 30, 45, and 60 days after operation. Corneal tissue harvested from the experimental group was observed using scanning electron microscope 15 days after operation to study ophthalmic biocompatibility and biodegradability. The water absorption rate and the swelling rate of the CHP blend membrane was 83.8% +/- 1.3% and 3.59 +/- 0.50, respectively. The tensile strength of the dry and the wet CHP blend membrane was (20.59 +/- 1.73) and (0.51 +/- 0.13) MPa, respectively. The breaking elongation rate of the dry and the wet CHP blend membrane was 10.69% +/- 1.16% and 53.15% +/- 2.46%, respectively. The CHP blend membrane had good permeability to NaCl and L-tyrosine. Absorbance (A) value of the experimental group 24, 48, and 72 hours after breeding was 0.207 +/- 0.083, 0.174 +/- 0.080, and 0.181 +/- 0.048, respectively, while the A value of the control group was 0.284 +/- 0.011, 0.272 +/- 0.083, and 0.307 +/- 0.056, respectively. Significant difference was evident between two groups (P < 0.05). In the experimental group, a small amount of floccus was exuded around the implanted membrane 1 day after operation; the floccus was absorbed on the third day, and there was no obvious inflammatory reaction occurring on the eleventh day. Most of the membrane degraded on the sixtieth day. Scanning electron microscope observation showed that the hexagonal morphology of the corneal endothelial cells was intact, and no degradation particles adhered to the surface. In the control group, the implantation of SK gel into anterior chamber was unsuccessful because the SK gel was quite soft and easily broken. In the experimental group, mild hyperemia emerged around the implanted membrane 1 day after the subconjunctival implantation of the membrane, and it became normal on the ninth day. No corneal edema and inflammatory reaction of anterior chamber occurred till the sixtieth day. The results in the control group and the experiment group were similar. Due to its good physicochemical properties and biocompatibility, the CHP blend membrane has potential applications in glaucoma filtering surgery.

Study on structure and hydrophobicity of PP/EVA co-blending membrane: Quenching rate

NASA Astrophysics Data System (ADS)

Tang, Na; Li, Zhao; Hua, Xinxin

2017-03-01

Isotactic polypropylene (iPP)/ethylene vinyl acetate (EVA) co-blending hydrophobic microporous membranes for vacuum membrane distillation (VMD) were prepared via thermally induced phase separation (TIPS). In the process of preparation, quenching rate has a great influence on the membrane morphology.

Polyethersulfone/polyacrylonitrile blended ultrafiltration membranes: preparation, morphology and filtration properties.

PubMed

Pasaoglu, Mehmet Emin; Guclu, Serkan; Koyuncu, Ismail

Polyethersulfone (PES)/polyacrylonitrile (PAN) membranes have been paid attention among membrane research subjects. However, very few studies are included in the literature. In our study, asymmetric ultrafiltration (UF) membranes were prepared from blends of PES/PAN with phase inversion method using water as coagulation bath. Polyvinylpyrrolidone (PVP) with Mw of 10,000 Da was used as pore former agent. N,N-dimethylformamide was used as solvent. The effects of different percentage of PVP and PES/PAN composition on morphology and water filtration properties were investigated. Membrane performances were examined using pure water and lake water filtration studies. Performances of pure water were less with the addition of PAN into the PES polymer casting solutions. However, long-term water filtration tests showed that PES/PAN blend membranes anti-fouling properties were much higher than the neat PES membranes. The contact angles of PES/PAN membranes were lower than neat PES membranes because of PAN addition in PES polymer casting solutions. Furthermore, it was found that PES/PAN blend UF membranes' dynamic mechanical analysis properties in terms of Young's modules were less than neat PES membrane because of decreasing amount of PES polymer.

Biodegradation test of SPS-LS blends as polymer electrolyte membrane fuel cells

NASA Astrophysics Data System (ADS)

Putri, Zufira; Arcana, I. Made

2014-03-01

Sulfonated polystyrene (SPS) can be applied as a proton exchange membrane fuel cell due to its fairly good chemical stability. In order to be applied as polymer electrolyte membrane fuel cells (PEMFCs), membrane polymer should have a good ionic conductivity, high proton conductivity, and high mechanical strength. Lignosulfonate (LS) is a complex biopolymer which has crosslinks and sulfonate groups. SPS-LS blends with addition of SiO2 are used to increase the proton conductivity and to improve the mechanical properties and thermal stability. However, the biodegradation test of SPS-LS blends is required to determine whether the application of these membranes to be applied as an environmentally friendly membrane. In this study, had been done the synthesis of SPS, biodegradability test of SPS-LS blends with variations of LS and SiO2 compositions. The biodegradation test was carried out in solid medium of Luria Bertani (LB) with an activated sludge used as a source of microorganism at incubation temperature of 37°C. Based on the results obtained indicated that SPS-LS-SiO2 blends are more decomposed by microorganism than SPS-LS blends. This result is supported by analysis of weight reduction percentage, functional groups with Fourier Transform Infrared (FTIR) Spectroscopy, and morphological surface with Scanning Electron Microscopy (SEM).

Improving CO2 permeation and separation performance of CO2-philic polymer membrane by blending CO2 absorbents

NASA Astrophysics Data System (ADS)

Cheng, Jun; Hu, Leiqing; Li, Yannan; Liu, Jianzhong; Zhou, Junhu; Cen, Kefa

2017-07-01

To research effects of CO2 absorption capacity and type of CO2 absorbent on the CO2 separation and free-volume properties of facilitated transport membranes, two types of CO2 absorbents, namely monoethanolamine (MEA) and ionic liquids (ILs:[P66614][Triz] and [P66614][2-Op]), were adopted. The CO2 absorption capacities of MEA, [P66614][Triz] and [P66614][2-Op] were about 0.561 mol CO2 per mol, 0.95 mol CO2 per mol and 1.60 mol CO2 per mol, respectively. All mean free-volume hole radiuses of membranes decreased after blending CO2 absorbents. After polymer membrane blended with two ILs, number of free-volume hole increased, resulting in modest increase of the fractional free volume. Both CO2 permeability and selectivity increased after blending MEA and ILs. The increasing range of CO2 permeability corresponded with CO2 absorption capacity of CO2 absorbents, and membrane blending with [P66614][2-Op] showed the highest CO2 permeability of 672.1 Barrers at 25 °C. Pebax/PEGDME membrane blending with MEA obtained the highest CO2/H2 and CO2/CH4 selectivity at 17.8 and 20.5, respectively.

Deproteinised natural rubber latex grafted poly(dimethylaminoethyl methacrylate) - poly(vinyl alcohol) blend membranes: Synthesis, properties and application.

PubMed

Jayadevan, Janisha; Alex, Rosamma; Gopalakrishnapanicker, Unnikrishnan

2018-02-01

Natural rubber latex was initially deproteinised (DNRL) and then subjected to physicochemical modifications to make high functional membranes for drug delivery applications. Initially, DNRL was prepared by incubating with urea, sodiumdodecylsulphate and acetone followed by centrifugation. The deproteinisation was confirmed by CHN analysis. The DNRL was then chemically modified by grafting (dimethylaminoethyl methacrylate) onto NR particles by using a redox initiator system viz; cumene hydroperoxide/tetraethylenepentamine, followed by dialysis for purification. The grafting was confirmed by dynamic light scattering, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The grafted system was blended with a hydrophilic adhesive polymer PVA and casted into membranes. The membranes after blending showed enhanced mechanical properties with a threshold concentration of PVA. The moisture uptake, swelling and water contact angle experiments indicated an increased hydrophilicity with an increased PVA content in the blend membranes. The grafted DNRL possessed significant antibacterial property which has been found to be retained in the blended form. A notable decrease in cytotoxicity was observed for the modified DNRL membranes than the bare DNRL membranes. The in-vitro drug release studies using rhodamine B as a model drug, confirmed the utility of the prepared membranes to function as a drug delivery matrix. Copyright © 2017 Elsevier B.V. All rights reserved.

Relaxation spectra of binary blends: Extension of the Doi-Edwards theory

NASA Astrophysics Data System (ADS)

Tchesnokov, M. A.; Molenaar, J.; Slot, J. J. M.; Stepanyan, R.

2007-10-01

A molecular model is presented which allows the calculation of the stress relaxation function G for binary blends consisting of two monodisperse samples with arbitrary molecular weights. It extends the Doi-Edwards reptation theory (Doi M. and Edwards S. F., The Theory of Polymer Dynamics (Oxford Press, New York) 1986) to highly polydisperse melts by including constraint release (CR) and thermal fluctuations (CLF), yet making use of the same input parameters. The model reveals an explicit nonlinear dependence of CR frequency in the blend on the blend's molecular weight distribution (MWD). It provides an alternative way to quantify polydisperse systems compared to the widely used "double-reptation" theories. The results of the present model are in a good agreement with the experimental data given in Rubinstein M. and Colby R. H., J. Chem. Phys., 89 (1988) 5291.

Proton-conducting membrane based on epoxy resin-poly(vinyl alcohol)-sulfosuccinic acid blend and its nanocomposite with sulfonated multiwall carbon nanotubes for fuel-cell application

NASA Astrophysics Data System (ADS)

Kakati, Nitul; Das, Gautam; Yoon, Young Soo

2016-01-01

A blend of poly(vinyl alcohol) (PVA) with diglycidyl ether of bisphenol-A (DGB) in the presence of sulfosuccinic acid (SSA) was investigated as hydrolytically-stable proton-conducting membrane. The PVA modification was carried out by varying the DGB:SSA ratio (20:20, 10:20, and 5:20). A nanocomposite of the blend (20:20) was prepared with sulfonated multiwall carbon nanotubes (viz., 1, 3 and 5 wt%). The water uptake behavior and the proton conductivity of the prepared membranes were evaluated. The ionic conductivity of the membranes and the water uptake behavior depended on the s-MWCNT and the DGB contents. The ionic conductivity showed an enhancement for the blend and for the nanocomposite membrane as compared to the pristine polymer.

Thermal profiles, crystallization behaviors and microstructure of diacylglycerol-enriched palm oil blends with diacylglycerol-enriched palm olein.

PubMed

Xu, Yayuan; Zhao, Xiaoqing; Wang, Qiang; Peng, Zhen; Dong, Cao

2016-07-01

To elucidate the possible interaction mechanisms between DAG-enriched oils, this study investigated how mixtures of DAG-enriched palm-based oils influenced the phase behavior, thermal properties, crystallization behaviors and the microstructure in binary fat blends. DAG-enriched palm oil (PO-DAGE) was blended with DAG-enriched palm olein (POL-DAGE) in various percentages (0%, 10%, 30%, 50%, 70%, 90%, 100%). Based on the observation of iso-solid diagram and phase diagram, the binary mixture of PO-DAGE/POL-DAGE showed a better compatibility in comparison with their corresponding original blends. DSC thermal profiles exhibited that the melting and crystallization properties of PO-DAGE/POL-DAGE were distinctively different from corresponding original blends. Crystallization kinetics revealed that PO-DAGE/POL-DAGE blends displayed a rather high crystallization rate and exhibited no spherulitic crystal growth. From the results of polarized light micrographs, PO-DAGE/POL-DAGE blends showed more dense structure with very small needle-like crystals than PO/POL. X-ray diffraction evaluation revealed when POL-DAGE was added in high contents to PO-DAGE, above 30%, β-polymorph dominated, and the mount of β' forms crystals was decreasing. Copyright © 2016 Elsevier Ltd. All rights reserved.

Separation of macromolecular proteins and rejection of toxic heavy metal ions by PEI/cSMM blend UF membranes.

PubMed

Kanagaraj, P; Nagendran, A; Rana, D; Matsuura, T; Neelakandan, S

2015-01-01

The charged surface modifying macromolecule (cSMM) was blended into the casting solution of poly(ether imide) (PEI) to prepare surface modified ultrafiltration membranes by phase inversion technique. The separation of proteins including bovine serum albumin, egg albumin, pepsin and trypsin was investigated by the fabricated membranes. On increasing cSMM content, solute rejection decreases whereas membrane flux increases. The pore size and surface porosity of the 5 wt% cSMM blend PEI membranes increases to 41.4 Å and 14.8%, respectively. Similarly, the molecular weight cut-off of the membranes ranged from 20 to 45 kDa, depending on the various compositions of the prepared membranes. The toxic heavy metal ions Cu(II), Cr(III), Zn(II) and Pb(II) from aqueous solutions were subjected to rejection by the prepared blended membrane with various concentration of polyethyleneimine (PETIM) as water soluble polymeric ligand. It was found that the rejection behavior of metal ion depends on the PETIM concentration and the stability complexation of metal ion with ligand. Copyright © 2014 Elsevier B.V. All rights reserved.

Viability and Biomechanics of Diced Cartilage Blended With Platelet-Rich Plasma and Wrapped With Poly (Lactic-Co-Glycolic) Acid Membrane.

PubMed

Liao, Jun-Lin; Chen, Jia; He, Bin; Chen, Yong; Xu, Jia-Qun; Xie, Hong-Ju; Hu, Feng; Wang, Ai-Jun; Luo, ChengQun; Li, Qing-Feng; Zhou, Jian-Da

2017-09-01

The objective of this study was to investigate the viability and biomechanics of diced cartilage blended with platelet-rich plasma (PRP) and wrapped with poly (lactic-co-glycolic) acid (PLGA) membrane in a rabbit model. A total of 10 New Zealand rabbits were used for the study. Cartilage grafts were harvested from 1 side ear. The grafts were divided into 3 groups for comparison: bare diced cartilage, diced cartilage wrapped with PLGA membrane, and diced cartilage blended with PRP and wrapped with PLGA membrane. Platelet-rich plasma was prepared using 8 mL of auricular blood. Three subcutaneous pockets were made in the backs of the rabbits, and the grafts were placed in these pockets. The subcutaneous implant tests were conducted for safety assessment of the PLGA membrane in vivo. All of the rabbits were sacrificed at the end of 3 months, and the specimens were collected. The sections were stained with hematoxylin and eosin, toluidin blue, and collagen II immunohistochemical. Simultaneously, biomechanical properties of grafts were assessed. This sample of PLGA membrane was conformed to the current standard of biological evaluation of medical devices. Moderate resorption was seen at the end of 3 months in the gross assessment in diced cartilage wrapped with PLGA membrane, while diced cartilage blended with PRP had no apparent resorption macroscopically and favorable viability in vivo after 3 months, and the histological parameters supported this. Stress-strain curves for the compression test indicated that the modulus of elasticity of bare diced cartilage was 7.65 ± 0.59 MPa; diced cartilage wrapped with PLGA membrane was 5.98 ± 0.45 MPa; and diced cartilage blended with PRP and wrapped with PLGA membrane was 7.48 ± 0.55 MPa, respectively. Diced cartilage wrapped with PLGA membrane had moderate resorption macroscopically after 3 months. However, blending with PRP has beneficial effects in improving the viability of diced cartilages. Additionally, the compression modulus of diced cartilage blended with PRP and wrapped with PLGA membrane was similar to bare diced cartilage.

Preparation and characterization of hydrophobic P(TFE) blend electrospun gel polymer electrolyte fibrous membranes for Li-O2 battery

NASA Astrophysics Data System (ADS)

Padmaraj, O.; Suthanthiraraj, S. Austin

2018-04-01

A novel stable electrospun gel polymer electrolyte [(100-x)% P(VdF-co-HFP)+(x)% P(TFE), (x = 5, 10, 15, 20, 25 & 30)/1 M Li(CF3SO2)2N-] fibrous membranes with an addition of various concentrations of hydrophobic P(TFE) polymer were prepared by an electrospinning technique. All the prepared electrospun polymer blend fibrous membranes were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, high resolution scanning electron microscopy techniques and water contact angle measurements. The newly developed electrospun pure and hydrophobic P(TFE) blend fibrous membranes were activated into separator-cum gel polymer electrolyte fibrous membranes by soaking in an electrolyte solution contains 1 M Li(CF3SO2)2N- in EC: PC (1:1, v/v) in an argon filled glove box. Among the various concentrations of hydrophobic P(TFE) blend polymer fibrous membranes, the electrospun gel polymer blend electrolyte with 5% P(TFE) showed low crystallinity, high thermal stability, high electrolyte uptake, good hydrophobicity and high ionic conductivity (2.680×10-2 S cm-1) at room temperature.

Structure and properties of cellulose and cellulose/guar blend membranes prepared from the n-methyl morpholine n-oxide/water solvent system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Mengkui; Winter, W.T.

1995-12-01

This paper describes membranes of cellulose or its blends with guar gums. Their morphology, hydration behavior, mechanical properties and permselectivity are all dependent upon preparation conditions. Wet membranes exhibit decreased strength but increased elasticity with increasing guar content. Morphologies of the wet membranes range from microporous to macrovoids to systems of regularly arranged conduits and could be formed in a reproducible manner. Dry membranes were invariably dense. Both wet and dry membranes had markedly higher permeation rates for molecules with 400 < M < 4000 than similarly treated commercial cellulose dialysis membranes and the rates increased with increasing guar content.more » Dried membranes of either cellulose or the blends showed appreciable permselectivity in this same intermediate molecular weight range which disappeared with increasing guar content.« less

Biodegradation test of SPS-LS blends as polymer electrolyte membrane fuel cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Putri, Zufira, E-mail: zufira.putri@gmail.com, E-mail: arcana@chem.itb.ac.id; Arcana, I Made, E-mail: zufira.putri@gmail.com, E-mail: arcana@chem.itb.ac.id

Sulfonated polystyrene (SPS) can be applied as a proton exchange membrane fuel cell due to its fairly good chemical stability. In order to be applied as polymer electrolyte membrane fuel cells (PEMFCs), membrane polymer should have a good ionic conductivity, high proton conductivity, and high mechanical strength. Lignosulfonate (LS) is a complex biopolymer which has crosslinks and sulfonate groups. SPS-LS blends with addition of SiO{sub 2} are used to increase the proton conductivity and to improve the mechanical properties and thermal stability. However, the biodegradation test of SPS-LS blends is required to determine whether the application of these membranes tomore » be applied as an environmentally friendly membrane. In this study, had been done the synthesis of SPS, biodegradability test of SPS-LS blends with variations of LS and SiO{sub 2} compositions. The biodegradation test was carried out in solid medium of Luria Bertani (LB) with an activated sludge used as a source of microorganism at incubation temperature of 37°C. Based on the results obtained indicated that SPS-LS-SiO{sub 2} blends are more decomposed by microorganism than SPS-LS blends. This result is supported by analysis of weight reduction percentage, functional groups with Fourier Transform Infrared (FTIR) Spectroscopy, and morphological surface with Scanning Electron Microscopy (SEM)« less

Dehydration of dioxane by pervaporation using filled blend membranes of polyvinyl alcohol and sodium alginate.

PubMed

Kuila, Sunil Baran; Ray, Samit Kumar

2014-01-30

Pervaporation membranes were made by solution blending of polyvinyl alcohol (PVA) and sodium alginate (SA). Accordingly, five different blends with PVA:SA weight ratio of 75:25, 50:50, 25:75, 20:80 and 10:90 designated as PS1, PS2, PS3, PS4 and PS5, respectively, were prepared. Each of these blends was crosslinked with 2, 4 and 6 wt% glutaraldehyde and the resulting fifteen (5 × 3) membranes were used for pervaporative separation of 90 wt% dioxane in water. The membranes made from PS4 and PS5 were not stable during pervaporation experiments. Among the stable membranes PS3 membrane crosslinked with 2 wt% glutaraldehyde showed the best results for flux and selectivity. Thus, it was filled with nano size sodium montmorillonite filler and used for separation of dioxane-water mixtures over the entire concentration range of 80-99.5 wt% dioxane in water. The membranes were also characterized by mechanical properties, FTIR, SEM, DTA-TGA and XRD. Copyright © 2013 Elsevier Ltd. All rights reserved.

Polymeric blend nanocomposite membranes for ethanol dehydration-effect of morphology and membrane-solvent interactions

EPA Science Inventory

Nanocomposite membranes (NCMs) of sodium alginate/poly(vinyl pyrrolidone) blend polymers incorporated with varying concentrations of phosphotungstic acid (H3PW12O40) (PWA) nanoparticles have been prepared and used in ethanol dehydration by the pervaporation (PV) technique. Effe...

Electrospun nanofibrous SF/P(LLA-CL) membrane: a potential substratum for endothelial keratoplasty.

PubMed

Chen, Junzhao; Yan, Chenxi; Zhu, Mengyu; Yao, Qinke; Shao, Chunyi; Lu, Wenjuan; Wang, Jing; Mo, Xiumei; Gu, Ping; Fu, Yao; Fan, Xianqun

2015-01-01

Cornea transplant technology has progressed markedly in recent decades, allowing surgeons to replace diseased corneal endothelium by a thin lamellar structure. A thin, transparent, biocompatible, tissue-engineered substratum with corneal endothelial cells for endothelial keratoplasty is currently of interest. Electrospinning a nanofibrous structure can simulate the extracellular matrix and have beneficial effects for cell culture. Silk fibroin (SF) has good biocompatibility but poor mechanical properties, while poly(L-lactic acid-co-ε-caprolactone) (P(LLA-CL)) has good mechanical properties but poor biocompatibility. Blending SF with P(LLA-CL) can maintain the advantages of both these materials and overcome their disadvantages. Blended electrospun nanofibrous membranes may be suitable for regeneration of the corneal endothelium. The aim of this study was to produce a tissue-engineered construct suitable for endothelial keratoplasty. Five scaffolds containing different SF:P(LLA-CL) blended ratios (100:0, 75:25, 50:50, 25:75, 0:100) were manufactured. A human corneal endothelial (B4G12) cell line was cultured on the membranes. Light transmission, speed of cell adherence, cell viability (live-dead test), cell proliferation (Ki-67, BrdU staining), and cell monolayer formation were detected on membranes with the different blended ratios, and expression of some functional genes was also detected by real-time polymerase chain reaction. Different blended ratios of scaffolds had different light transmittance properties. The 25:75 blended ratio membrane had the best transmittance among these scaffolds. All electrospun nanofibrous membranes showed improved speed of cell adherence when compared with the control group, especially when the P(LLA-CL) ratio increased. The 25:75 blended ratio membranes also had the highest cell proliferation. B4G12 cells could form a monolayer on all scaffolds, and most functional genes were also stably expressed on all scaffolds. Only two genes showed changes in expression. All blended ratios of SF:P(LLA-CL) scaffolds were evaluated and showed good biocompatibility for cell adherence and monolayer formation. Among them, the 25:75 blended ratio SF:P(LLA-CL) scaffold had the best transmittance and the highest cell proliferation. These attributes further the potential application of the SF:P(LLA-CL) scaffold for corneal endothelial transplantation.

Dual-Functional Ultrafiltration Membrane for Simultaneous Removal of Multiple Pollutants with High Performance.

PubMed

Pan, Shunlong; Li, Jiansheng; Noonan, Owen; Fang, Xiaofeng; Wan, Gaojie; Yu, Chengzhong; Wang, Lianjun

2017-05-02

Simultaneous removal of multiple pollutants from aqueous solution with less energy consumption is crucial in water purification. Here, a novel concept of dual-functional ultrafiltration (DFUF) membrane is demonstrated by entrapment of nanostructured adsorbents into the finger-like pores of ultrafiltration (UF) membrane rather than in the membrane matrix in previous reports of blend membranes, resulting in an exceptionally high active content and simultaneous removal of multiple pollutants from water due to the dual functions of rejection and adsorption. As a demonstration, hollow porous Zr(OH) x nanospheres (HPZNs) were immobilized in poly(ether sulfone) (PES) UF membranes through polydopamine coating with a high content of 68.9 wt %. The decontamination capacity of DFUF membranes toward multiple model pollutants (colloidal gold, polyethylene glycol (PEG), Pb(II)) was evaluated against a blend membrane. Compared to the blend membrane, the DFUF membranes showed 2.1-fold increase in the effective treatment volume for the treatment of Pb(II) contaminated water from 100 ppb to below 10 ppb (WHO drinking water standard). Simultaneously, the DFUF membranes effectively removed the colloidal gold and PEG below instrument detection limit, however the blend membrane only achieved 97.6% and 96.8% rejection for colloidal gold and PEG, respectively. Moreover, the DFUF membranes showed negligible leakage of nanoadsorbents during testing; and the membrane can be easily regenerated and reused. This study sheds new light on the design of high performance multifunction membranes for drinking water purification.

Blend membrane of succinic acid-crosslinked chitosan grafted with heparin/PVA-PEG (polyvinyl alcohol-polyethylene glycol) and its characterization

NASA Astrophysics Data System (ADS)

Sangkota, V. D. A.; Lusiana, R. A.; Astuti, Y.

2018-04-01

Crosslinking and grafting reactions are required to modify the functional groups on chitosan to increase the number of its active groups. In this study, crosslinking reaction of succinic acid and grafting reaction of heparin on chitosan were conducted to produce a membrane as a candidate of a hemodialysis membrane. The mole ratio between chitosan and succinate acids was varied to obtain the best composition of modified materials. By blending all the material composition with PVA-PEG, the blend was transformed into a membrane. The resulted membrane was then characterized by various test methods such as tests of thickness, weight, water uptake, pH resistance, tensile strength and membrane hydrophilicity. The results showed that the best composition of the membrane reached in the addition of 0.011 gram of succinic acid proved by its highest mechanical strength compared to the other membranes.

Synthesis and characterization of biopolymer based mixed matrix membranes for pervaporative dehydration.

PubMed

Das, Paramita; Ray, Samit Kumar

2014-03-15

Several blend membranes were prepared from different weight ratios of polyvinyl alcohol (PVA) and hydroxyethyl cellulose (HEC) and these unfilled membranes were crosslinked with maleic acid. In a similar way mixed matrix blend membranes were also prepared by varying weight ratio of PVA and HEC with micro and nano bentonite filler in each of these blends. These membranes were used for pervaporative dehydration of 89 wt% tetrahydrofuran (THF). Three membranes designated as UF (unfilled), MF2 (containing 2 wt% micro filler) and NF2 (containing 2 wt% nano filler) showing the best results for flux and selectivity were identified. These membranes were characterized by FTIR, UV, XRD and DTA-TG and used for separation of 80-99 wt% THF from water by pervaporation. The NF2 membrane was found to show the best results in terms of flux and separation factor. Copyright © 2013 Elsevier Ltd. All rights reserved.

Non-woven PET fabric reinforced and enhanced the performance of ultrafiltration membranes composed of PVDF blended with PVDF-g-PEGMA for industrial applications

NASA Astrophysics Data System (ADS)

Wang, Shuai; Li, Tong; Chen, Chen; Chen, Sheng; Liu, Baicang; Crittenden, John

2018-03-01

Ultrafiltration (UF) membranes composed of poly(vinylidene fluoride) (PVDF) blended with poly(vinylidene fluoride)-graft-poly(ethylene glycol) methyl ether methacrylate (PVDF-g-PEGMA) can present high flux and excellent foulant removal efficiencies under suitable preparation conditions. However, these PVDF/PVDF-g-PEGMA blended membranes cannot be applied industrially because of the insufficient mechanical strength (strength-to-break value of 8.4 ± 0.6 MPa). We incorporated two types of non-woven polyethylene terephthalate (PET) fabrics (thin hydrophobic and thick hydrophilic fabrics) as support layers to improve the mechanical properties of the blended membranes. The thin and thick PET fabrics were able to significantly improve the tensile strength to 23.3 ± 3.7 MPa and 30.1 ± 1.4 MPa, respectively. The PET fabrics had a limited impact on the separation-related membrane performance such as hydrophilicity, foulant rejection, whereas the mechanical strength and pure water flux was improved several folds. The enhanced flux was attributed to the higher surface porosity and wider finger-like voids in the cross-section. The thin PET fabric with larger porosity was able to maintain a consistent toughness simultaneously; thus it is recommended as a support material for this blended membrane.

Optical gravitational lensing experiment: OGLE-1999-BUL-19 - the first multipeak parallax event

NASA Astrophysics Data System (ADS)

Smith, Martin C.; Mao, Shude; Woźniak, P.; Udalski, A.; Szymański, M.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Żebruń, K.

2002-10-01

We describe a highly unusual microlensing event, OGLE-1999-BUL-19. Unlike most standard microlensing events, this event exhibits multiple peaks in its light curve. The Einstein radius crossing time for this event is approximately 1 yr, which is unusually long. We show that the additional peaks in the light curve can be caused by the very small value for the relative transverse velocity of the lens projected on to the observer plane (). Since this value is significantly less than the speed of the orbit of the Earth around the Sun (v⊕~ 30km s-1), the motion of the Earth induces these multiple peaks in the light curve. This value for is the lowest velocity so far published and we believe that this is the first multiple-peak parallax event ever observed. We also found that the event can be somewhat better fitted by a rotating binary-source model, although this is to be expected since every parallax microlensing event can be exactly reproduced by a suitable binary-source model. A face-on rotating binary-lens model was also identified, but this provides a significantly worse fit. We conclude that the most likely cause for this multipeak behaviour is parallax microlensing rather than microlensing by a binary source. However, this event may be exhibiting a slight binary-source signature in addition to these parallax-induced multiple peaks. With spectroscopic observations it is possible to test this `parallax plus binary-source' hypothesis and (in the instance that the hypothesis turns out to be correct) to simultaneously fit both models and obtain a measurement of the lens mass. Furthermore, spectroscopic observations could also supply information regarding the lens properties, possibly providing another avenue for determining the lens mass. We also investigated the nature of the blending for this event, and found that the majority of the I-band blending is contributed by a source roughly aligned with the lensed source. This implies that most of the I-band blending is caused by light from the lens or a binary companion to the source. However, in the V band, there appears to be a second blended source 0.35 arcsec away from the lensed source. Hubble Space Telescope observations will be very useful for understanding the nature of the blends. We also suggest that a radial velocity survey of all parallax events will be very useful for further constraining the lensing kinematics and understanding the origins of these events and the excess of long events toward the bulge.

Identification and measurement of intermolecular interaction in polyester/polystyrene blends by FTIR-photoacoustic spectrometry

USDA-ARS?s Scientific Manuscript database

Fourier transform infrared photoacoustic spectrometry was used to reveal and identify n-p type intermolecular interaction formed in plastic comprising binary blends of polystyrene and a biodegradable polymer, either polylactic acid, polycaprolactone or poly(tetramethyleneadipate-co-terephthalate)....

Blends of polyester ionomers with polar polymers: Interactions, reactions, and compatibilization

NASA Astrophysics Data System (ADS)

Boykin, Timothy Lamar

The compatibility of amorphous and semicrystalline polyester ionomers with various polar polymers (i.e., polyesters and polyamides) has been investigated for their potential use as minor component compatibilizers. The degree of compatibility (i.e., ranging from incompatible to miscible) between the polyester ionomers and the polar polymers was determined by evaluating the effect of blend composition on the melting behavior and phase behavior of binary blends. In addition, the origin of compatibility and/or incompatibility for each of the binary blends (i.e., polyamide/ionomer and polyester/ionomer) was determined by evaluating blends prepared by both solution and melt mixed methods. Subsequent to investigation of the binary blends, the effect of polyester ionomer addition on the compatibility of polyamide/polyester blends was investigated by evaluating the mechanical properties and phase morphology of ionomer compatibilized polyamide/polyester blends. Polyester ionomers (amorphous and semicrystalline) were shown to exhibit a high degree of compatibility (even miscibility) with polyamides, such as nylon 6,6 (N66). Compatibility was attributed to specific interactions between the metal counterion of the polyester ionomer and the amide groups of N66. The degree of compatibility (or miscibility) was shown to be dependent on the counterion type of the ionomer, with the highest degree exhibited by blends containing the divalent form of the polyester ionomers. Although polyester ionomers were shown to exhibit incompatibility with both poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT), increasing the time of melt processing significantly enhanced the compatibility of the polyester ionomers with both PET and PBT. The observed enhancement in compatibility was attributed to ester-ester interchange between the polyester blend components, which was confirmed by NMR spectroscopy. The addition of polyester ionomers as a minor component compatibilizer (i.e., 2 to 5 wt%) resulted in significant enhancement in the impact strength and a dramatic improvement in the tensile properties compared to uncompatibilized blends of nylon 6,6 (N66) with poly(butylene terephthalate) (PBT). This behavior was attributed to an increase in the interfacial adhesion between the phase-separated domains due to strong interactions between the polyester ionomer and N66. The placement of the ionomer compatibilizer at the N66/PBT interface was facilitated by pre-extrusion of the polyester ionomer with PBT, prior to extrusion with N66.

Preparation and characterization of polymer blend based on sulfonated poly (ether ether ketone) and polyetherimide (SPEEK/PEI) as proton exchange membranes for fuel cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hashim, Nordiana; Ali, Ab Malik Marwan; Lepit, Ajis

2015-08-28

Blends of sulfonated poly (ether ether ketone) (SPEEK) and polyetherimide (PEI) were prepared in five different weight ratios using N-methyl-2-pyrrolidone (NMP) as solvent by the solution cast technique. The degree of sulfonation (DS) of the sulfonated PEEK was determined from deuterated dimethyl sulfoxide (DMSO-d{sub 6}) solution of the purified polymer using {sup 1}H NMR method. The properties studied in the present investigation includes conductivity, water uptake, thermal stability and structure analysis of pure SPEEK as well as SPEEK-PEI polymer blend membranes. The experimental results show that the conductivity of the membranes increased with increase in temperature from 30 to 80°C,more » except for that of pure SPEEK membrane which increased with temperature from 30 to 60°C while its conductivity decreased with increasing temperature from 60 to 80°C. The conductivity of 70wt.%SPEEK-30wt.%PEI blend membrane at 80% relative humidity (RH) is found to be 1.361 × 10{sup −3} Scm{sup −1} at 30°C and 3.383 × 10{sup −3} Scm{sup −1} at 80°C respectively. It was also found that water uptake and thermal stability of the membranes slightly improved upon blending with PEI. Structure analysis was carried out using Fourier Transform Infrared (FTIR) spectroscopy which revealed considerable interactions between sulfonic acid group of SPEEK and imide groups of PEI. Modification of SPEEK by blending with PEI shows good potential for improving the electrical and physical properties of proton exchange membranes.« less

Composite Electrolyte Membranes from Partially Fluorinated Polymer and Hyperbranched, Sulfonated Polysulfone

PubMed Central

Subianto, Surya; Roy Choudhury, Namita; Dutta, Naba

2013-01-01

Macromolecular modification of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF) was done with various proportions of sulfonic acid terminated, hyperbranched polysulfone (HPSU) with a view to prepare ion conducting membranes. The PVDF-co-HFP was first chemically modified by dehydrofluorination and chlorosulfonation in order to make the membrane more hydrophilic as well as to introduce unsaturation, which would allow crosslinking of the PVDF-co-HFP matrix to improve the stability of the membrane. The modified samples were characterized for ion exchange capacity, morphology, and performance. The HPSU modified S-PVDF membrane shows good stability and ionic conductivity of 5.1 mS cm−1 at 80 °C and 100% RH for blends containing 20% HPSU, which is higher than the literature values for equivalent blend membranes using Nafion. SEM analysis of the blend membranes containing 15% or more HPSU shows the presence of spherical domains with a size range of 300–800 nm within the membranes, which are believed to be the HPSU-rich area. PMID:28348282

Effect of Modified Nanoclay Composite on Blended PVDF/PEG Electrolyte Membranes for Fuel Cell Applications

NASA Astrophysics Data System (ADS)

Bahavan Palani, P.; Sainul Abidin, K.; Kannan, R.; Rajashabala, S.

This research work describes the fabrication of polymer blend nanocomposite membranes using the solution casting method. These membranes were fabricated with Poly (Vinylidene Fluoride) (PVdF) as host, Poly (Ethylene Glycol) (PEG) in steps of 2wt.% as blending polymer and Montmorillonite (MMT) nanoclay particles in steps of 3wt.% which were used as received. The protonated MMT was synthesized through an ion exchange process with column chromatographic technique. The prepared membrane’s performance was investigated using different characterization techniques of Thermo Gravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), water uptake, IEC and electrochemical impedance spectroscopy. Thermal stability was decreased while adding PEG into PVDF but it is controlled with the addition of MMT on PVDF/PEG blend matrix. Moreover, It is noticed that, the increase of water uptake, IEC by the increasing additive concentration of PEG and MMT. XRD studies reveal the increased amorphous phase with uniform exfoliation of nanoclay particles. The highest proton conductivity value of 0.127S cm‑1 is obtained with 9wt.% of MMT in the PVdF/PEG/MMT composite membranes at room temperature with 100% Relative Humid (RH) condition and 10 V.% of sulfonation. The blended nanocomposite membranes fulfill the requirements of proton exchange membrane for fuel cell application.

Bark Beetle pheromones and pine volatiles: Attractant Kairomone Lure Blend for Longhorn Beetles (Cerambycidae) in pine stands of the southeastern United States.

Treesearch

Dan Miller; Chris Asaro; Christopher Crowe; Donald Duerr

2011-01-01

In 2006,weexamined the ßight responses of 43 species of longhorn beetles (Coleoptera: Cerambycidae) to multiple-funnel traps baited with binary lure blends of 1) ipsenol + ipsdienol, 2) ethanol + α-pinene, and a quaternary lure blend of 3) ipsenol + ipsdienol + ethanol + αpinene in the southeastern United States. In addition, we monitored responses of...

Assessment of Blend PVDF Membranes, and the Effect of Polymer Concentration and Blend Composition

PubMed Central

Bamaga, Omar A.; Abdel-Aziz, M. H.

2018-01-01

In this work, PVDF homopolymer was blended with PVDF-co-HFP copolymer and studied in terms of morphology, porosity, pore size, hydrophobicity, permeability, and mechanical properties. Different solvents, namely N-Methyl-2 pyrrolidone (NMP), Tetrahydrofuran (THF), and Dimethylformamide (DMF) solvents, were used to fabricate blended PVDF flat sheet membranes without the introduction of any pore forming agent, through a non-solvent induced phase separation (NIPS) technique. Furthermore, the performance of the fabricated membranes was investigated for pressure and thermal driven applications. The porosity of the membranes was slightly increased with the increase in the overall content of PVDF and by the inclusion of PVDF copolymer. Total PVDF content, copolymer content, and mixed-solvent have a positive effect on mechanical properties. The addition of copolymer increased the hydrophobicity when the total PVDF content was 20%. At 25% and with the inclusion of mixed-solvent, the hydrophobicity was adversely affected. The permeability of the membranes increased with the increase in the overall content of PVDF. Mixed-solvents significantly improved permeability. PMID:29510555

Hydrophilicity and antifouling property of membrane materials from cellulose acetate/polyethersulfone in DMAc.

PubMed

Sun, Zhonghua; Chen, Fushan

2016-10-01

In this study, cellulose acetate (CA) was blended with polyethersulfone (PES) to endow the ultrafiltration membrane with the improved hydrophilicity and antifouling property by using N,N-dimethylacetamide (DMAc) as the solvent. The effects of blend composition and evaporation time on the mechanical strength and pure water flux were investigated. It was found that the optimal composition of the casting solution was: 18wt% (PES), 4wt% (Polyvinylpyrrolidone K30), 3wt% (CA) and 20s (Evaporation time). The characteristics of CA-PES blend membranes were investigated through the methods of contact angle goniometer, antifouling property, compatibility, thermo gravimetric analysis and SEM. The results showed that the hydrophilicity and antifouling property of CA-PES ultrafiltration membranes were enhanced in comparison with the pure PES membranes. The CA-PES membranes exhibited semi-compatibility and good thermal stability below 270°C. This study provided a potential industrial application prospect of CA-PES membranes prepared in DMAc. Copyright © 2016 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hongfei; Yang, Zhenhua; Pan, Cheng

Here, we report that the addition of a non-photoactive tertiary polymer phase in the binary bulk heterojunction (BHJ) polymer solar cell leads to a self-assembled columnar nanostructure, enhancing the charge mobilities and photovoltaic efficiency with surprisingly increased optimal active blend thicknesses over 300 nm, 3–4 times larger than that of the binary counterpart. Using the prototypical poly(3-hexylthiophene) (P3HT):fullerene blend as a model BHJ system, we discover that the inert poly(methyl methacrylate) (PMMA) added in the binary BHJ blend self-assembles into vertical columns, which not only template the phase segregation of electron acceptor fullerenes but also induce the out-of-plane rotation ofmore » the edge-on-orientated crystalline P3HT phase. Using complementary interrogation methods including neutron reflectivity, X-ray scattering, atomic force microscopy, transmission electron microscopy, and molecular dynamics simulations, we show that the enhanced charge transport originates from the more randomized molecular stacking of the P3HT phase and the spontaneous segregation of fullerenes at the P3HT/PMMA interface, driven by the high surface tension between the two polymeric components. The results demonstrate a potential method for increasing the thicknesses of high-performance polymer BHJ solar cells with improved photovoltaic efficiency, alleviating the burden of stringently controlling the ultrathin blend thickness during the roll-to-roll-type large-area manufacturing environment.« less

Using color photometry to separate transiting exoplanets from false positives

NASA Astrophysics Data System (ADS)

Tingley, B.

2004-10-01

The radial velocity technique is currently used to classify transiting objects. While capable of identifying grazing binary eclipses, this technique cannot reliably identify blends, a chance overlap of a faint background eclipsing binary with an ordinary foreground star. Blends generally have no observable radial velocity shifts, as the foreground star is brighter by several magnitudes and therefore dominates the spectrum, but their combined light can produce events that closely resemble those produced by transiting exoplanets. The radial velocity technique takes advantage of the mass difference between planets and stars to classify exoplanet candidates. However, the existence of blends renders this difference an unreliable discriminator. Another difference must therefore be utilized for this classification - the physical size of the transiting body. Due to the dependence of limb darkening on color, planets and stars produce subtly different transit shapes. These differences can be relatively weak, little more than 1/10th the transit depth. However, the presence of even small color differences between the individual components of the blend increases this difference. This paper shows that this color difference is capable of discriminating between exoplanets and blends reliably, theoretically capable of classifying even terrestrial-class transits, unlike the radial velocity technique.

Exploiting Photo-induced Reactions in Polymer Blends to Create Hierarchically Ordered, Defect-free Materials

ScienceCinema

Balazs, Anna [University of Pittsburgh, Pittsburgh, Pennsylvania, United States

2017-12-09

Computer simulations reveal how photo-induced chemical reactions can be exploited to create long-range order in binary and ternary polymeric materials. The process is initiated by shining a spatially uniform light over a photosensitive AB binary blend, which undergoes both a reversible chemical reaction and phase separation. We then introduce a well-collimated, higher-intensity light source. Rastering this secondary light over the sample locally increases the reaction rate and causes formation of defect-free, spatially periodic structures. These binary structures resemble either the lamellar or hexagonal phases of microphase-separated di-block copolymers. We measure the regularity of the ordered structures as a function of the relative reaction rates for different values of the rastering speed and determine the optimal conditions for creating defect-free structures in the binary systems. We then add a non-reactive homo-polymer C, which is immiscible with both A and B. We show that this component migrates to regions that are illuminated by the secondary, higher-intensity light, allowing us to effectively write a pattern of C onto the AB film. Rastering over the ternary blend with this collimated light now leads to hierarchically ordered patterns of A, B, and C. The findings point to a facile, non-intrusive process for manufacturing high-quality polymeric devices in a low-cost, efficient manner.

Dynamics and order-disorder transitions in bidisperse diblock copolymer blends

NASA Astrophysics Data System (ADS)

Wang, Yueqiang; Li, Xuan; Tang, Ping; Yang, Yuliang

2011-03-01

We employ the dynamic extension of self-consistent field theory (DSCFT) to study dynamics and order-disorder transitions (ODT) in AB diblock copolymer binary mixtures of two different monodisperse chain lengths by imitating the dynamic storage modulus G‧ corresponding to any given morphology in the oscillatory shear measurements. The different polydispersity index (PDI) is introduced by binary blending AB diblock copolymers with variations in chain lengths and chain number fractions. The simulation results show that the increase of polydispersity in the minority or symmetric block introduces a decrease in the segregation strength at the ODT, ( χN) ODT, whereas the increase of polydispersity in the majority block results in a decrease, then increase and final decrease again in ( χN) ODT. To the best of our knowledge, our DSCFT simulations, for the first time, predict an increase in ( χN) ODT with the PDI in the majority block, which produces the experimental results. The simulations by previous SCFT, which generally speaking, is capable of describing equilibrium morphologies, however, contradict the experimental data. The polydispersity acquired by properly tuning the chain lengths and number fractions of binary diblock copolymer blends should be a convenient and efficient way to control the microphase separation strength at the ODT.

Effect of Evaporation Time on Separation Performance of Polysulfone/Cellulose Acetate (PSF/CA) Membrane

NASA Astrophysics Data System (ADS)

Syahbanu, Intan; Piluharto, Bambang; Khairi, Syahrul; Sudarko

2018-01-01

Polysulfone and cellulose acetate are common material in separation. In this research, polysulfone/cellulose actetate (PSF/CA) blend membrane was prepared. The aim of this research was to study effect of evaporation time in casting of PSF/CA membrane and its performance in filtration. CA was obtained by acetylation process of bacterial cellulose (BC) from fermentation of coconut water. Fourier Transform Infra Red (FTIR) Spectroscopy was used to examine functional groups of BC, CA and commercial cellulose acetate. Subtitution of acetyl groups determined by titration method. Blend membranes were prepared through phase inversion technique in which composition of PSF/PEG/CA/NMP(%w) was 15/5/5/75. Polyethyleneglycol (PEG) and N-methyl-2-pyrrolidone (NMP) were act as pore forming agent and solvent, respectively. Variation of evaporation times were used as parameter to examine water uptake, flux, and morphology of PSF/CA blend membranes. FTIR spectra of CA show characteristic peak of acetyl group at 1220 cm-1 indicated that BC was acetylated succesfully. Degree of subtitution of BCA was found at 2.62. Highest water flux was performed at 2 bar obtained at 106.31 L.m-2.h-1 at 0 minute variation, and decrease as increasing evaporation time. Morphology of PSF/BCA blend membranes were investigated by Scanning Electron Microscopy (SEM) showed that porous asymetric membrane were formed.

Water–solid interactions in amorphous maltodextrin-crystalline sucrose binary mixtures

PubMed Central

Ghorab, Mohamed K.; Toth, Scott J.; Simpson, Garth J.; Mauer, Lisa J.; Taylor, Lynne S.

2016-01-01

Amorphous and crystalline solids are commonly found together in a variety of pharmaceutical and food products. In this study, the influence of co-formulation of amorphous maltodextrins (MDs) and crystalline sucrose (S) on moisture sorption, deliquescence, and glass transition (Tg) properties of powder blends was investigated. Individual components and binary mixtures of four different molecular weight MDs with sucrose in 1:1 w/w ratios were exposed to various relative humidity (RH) environments and their equilibrium and dynamic moisture contents were monitored. The deliquescence point (RH0) and dissolution behavior of sucrose alone and in blends was also monitored by polarized light microscopy and second harmonic generation imaging. In S:MD blends, the deliquescence RH of sucrose was lower than the RH0 of sucrose alone, and synergistic moisture sorption also occurred at RHs lower than the RH0. Intimate contact of sucrose crystals with the amorphous MDs resulted in complete dissolution of sucrose at RH < RH0. When blends were stored at conditions exceeding the Tg of the individual MDs (25 °C and 60%, 49% and 34%RH for MD21, MD29 and MD40, respectively), the Tg of the blends was lower than that of individual MDs. Thus, co-formulation of amorphous MDs with crystalline sucrose sensitizes the blend to moisture, potentially leading to deleterious changes in the formulation if storage conditions are not adequately controlled. PMID:23477494

Thin-film Nanofibrous Composite Membranes Containing Cellulose or Chitin Barrier Layers Fabricated by Ionic Liquids

DOE Office of Scientific and Technical Information (OSTI.GOV)

H Ma; B Hsiao; B Chu

The barrier layer of high-flux ultrafiltration (UF) thin-film nanofibrous composite (TFNC) membranes for purification of wastewater (e.g., bilge water) have been prepared by using cellulose, chitin, and a cellulose-chitin blend, regenerated from an ionic liquid. The structures and properties of regenerated cellulose, chitin, and a cellulose-chitin blend were analyzed with thermogravimetric analysis (TGA) and wide-angle X-ray diffraction (WAXD). The surface morphology, pore size and pore size distribution of TFNC membranes were determined by SEM images and molecular weight cut-off (MWCO) methods. An oil/water emulsion, a model of bilge water, was used as the feed solution, and the permeation flux andmore » rejection ratio of the membranes were investigated. TFNC membranes based on the cellulose-chitin blend exhibited 10 times higher permeation flux when compared with a commercial UF membrane (PAN10, Sepro) with a similar rejection ratio after filtration over a time period of up to 100 h, implying the practical feasibility of such membranes for UF applications.« less

A new strategy to engineer polymer bulk heterojunction solar cells with thick active layers via self-assembly of the tertiary columnar phase

DOE PAGES

Li, Hongfei; Yang, Zhenhua; Pan, Cheng; ...

2017-07-14

Here, we report that the addition of a non-photoactive tertiary polymer phase in the binary bulk heterojunction (BHJ) polymer solar cell leads to a self-assembled columnar nanostructure, enhancing the charge mobilities and photovoltaic efficiency with surprisingly increased optimal active blend thicknesses over 300 nm, 3–4 times larger than that of the binary counterpart. Using the prototypical poly(3-hexylthiophene) (P3HT):fullerene blend as a model BHJ system, we discover that the inert poly(methyl methacrylate) (PMMA) added in the binary BHJ blend self-assembles into vertical columns, which not only template the phase segregation of electron acceptor fullerenes but also induce the out-of-plane rotation ofmore » the edge-on-orientated crystalline P3HT phase. Using complementary interrogation methods including neutron reflectivity, X-ray scattering, atomic force microscopy, transmission electron microscopy, and molecular dynamics simulations, we show that the enhanced charge transport originates from the more randomized molecular stacking of the P3HT phase and the spontaneous segregation of fullerenes at the P3HT/PMMA interface, driven by the high surface tension between the two polymeric components. The results demonstrate a potential method for increasing the thicknesses of high-performance polymer BHJ solar cells with improved photovoltaic efficiency, alleviating the burden of stringently controlling the ultrathin blend thickness during the roll-to-roll-type large-area manufacturing environment.« less

The durability of concrete containing a high-level of fly ash or a ternary blend of supplementary cementing materials

NASA Astrophysics Data System (ADS)

Gilbert, Christine M.

The research for this study was conducted in two distinct phases as follows: Phase 1: The objective was to determine the effect of fly ash on the carbonation of concrete. The specimens made for this phase of the study were larger in size than those normally used in carbonation studies and were are meant to more accurately reflect real field conditions. The results from early age carbonation testing indicate that the larger size specimens do not have a measured depth of carbonation as great as that of the smaller specimens typically used in carbonation studies at the same age and under the same conditions. Phase 2: The objective was to evaluate the performance of ternary concrete mixes containing a ternary cement blend consisting of Portland cement, slag and Type C fly ash. It was found that concrete mixtures containing the fly ash with the lower calcium (CaO) content (in binary or ternary blends) provided superior durability performance and resistance to ASR compared to that of the fly ash with the higher CaO content. Ternary blends (regardless of the CaO content of the fly ash) provided better overall durability performance than binary blends of cementing materials or the control.

Compatibilized Immiscible Polymer Blends for Gas Separations

PubMed Central

Panapitiya, Nimanka; Wijenayake, Sumudu; Nguyen, Do; Karunaweera, Chamaal; Huang, Yu; Balkus, Kenneth; Musselman, Inga; Ferraris, John

2016-01-01

Membrane-based gas separation has attracted a great deal of attention recently due to the requirement for high purity gasses in industrial applications like fuel cells, and because of environment concerns, such as global warming. The current methods of cryogenic distillation and pressure swing adsorption are energy intensive and costly. Therefore, polymer membranes have emerged as a less energy intensive and cost effective candidate to separate gas mixtures. However, the use of polymeric membranes has a drawback known as the permeability-selectivity tradeoff. Many approaches have been used to overcome this limitation including the use of polymer blends. Polymer blending technology synergistically combines the favorable properties of different polymers like high gas permeability and high selectivity, which are difficult to attain with a single polymer. During polymer mixing, polymers tend to uncontrollably phase separate due to unfavorable thermodynamics, which limits the number of completely miscible polymer combinations for gas separations. Therefore, compatibilizers are used to control the phase separation and to obtain stable membrane morphologies, while improving the mechanical properties. In this review, we focus on immiscible polymer blends and the use of compatibilizers for gas separation applications. PMID:28773766

Enhanced proton conductivity by the influence of modified montmorillonite on poly (vinyl alcohol) based blend composite membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palani, P. Bahavan, E-mail: bahavanpalani@gmail.com; Abidin, K. Sainul; Kannan, R., E-mail: rksrsrk@gmail.com

2016-05-23

The highest proton conductivity value of 0.0802 Scm{sup −1} is obtained at 6 wt% of protonated MMT added to the PVA/PEG blends. The polymer blend composite membranes are prepared with varied concentration of Poly vinyl alcohol (PVA), Poly ethylene glycol (PEG) and Montmorillonite (MMT) by solution casting method. The Na{sup +} MMT was modified (protonated) to H{sup +} MMT with ion exchange process. The prepared membranes were characterized by using TGA, FTIR, XRD, Ion Exchange Capacity, Water/Methanol uptake, swelling ratio and proton conductivity. The significant improvements in the hydrolytic stability were observed. In addition, thermal stability of the composite membranesmore » were improved and controlled by the addition of MMT. All the prepared membranes are shown appreciable values of proton conductivity at room temperature with 100% relative humidity.« less

Controlling the Solidification of Organic Photovoltaic Blends with Nucleating Agents

NASA Astrophysics Data System (ADS)

Nekuda Malik, Jennifer A.; Treat, Neil D.; Abdelsamie, Maged; Yu, Liyang; Li, Ruipeng; Smilgies, Detlef-M.; Amassian, Aram; Hawker, Craig J.; Chabinyc, Michael L.; Stingelin, Natalie

2014-11-01

Blending fullerenes with a donor polymer for the fabrication of organic solar cells often leads to at least partial vitrification of one, if not both, components. For prototypical poly(3-hexylthiophene):fullerene blend, we show that the addition of a commercial nucleating agent, di(3,4-dimethyl benzylidene)sorbitol, to such binary blends accelerates the crystallization of the donor, resulting in an increase in its degree of crystallinity in as-cast structures. This allows manipulation of the extent of intermixing/ phase separation of the donor and acceptor directly from solution, offering a tool to improve device characteristics such as power conversion efficiency.

Influence of Pectin as a green polymer electrolyte on the transport properties of Chitosan-Pectin membranes.

PubMed

Pasini Cabello, S D; Ochoa, N A; Takara, E A; Mollá, S; Compañ, V

2017-02-10

Novel blend membranes have been prepared from Chitosan (CH), Pectin (PEC) and their mixtures. The obtained samples were cross-linked and sulfonated before characterization. The results show that CH/PEC membranes display structural changes on the chemical and physical properties as a function of composition. DSC analysis reveals an endothermic peak due to the scission of the ionic pairs between carboxylic groups and ammonium groups, which produces a strong change on physical properties such as methanol permeability and proton conductivity. The methanol permeability decreases with the amount of Pectin from (4.24±0.04)×10 -6 cm 2 /s for pure Chitosan membrane to (1.51±0.03)×10 -6 cm 2 /s for blend CH/PEC membranes when the amount of Pectin is 50% (v/v). The proton conductivities of the blend membranes follow a similar behavior. For a pure CH membrane the conductivity is 2.44×10 -3 S/cm, decreasing with pectin content until the composition 50/50 (v/v), in which the conductivity drops almost one order of magnitude. Copyright © 2016 Elsevier Ltd. All rights reserved.

Polymer ligand–induced autonomous sorting and reversible phase separation in binary particle blends

DOE PAGES

Schmitt, Michael; Zhang, Jianan; Lee, Jaejun; ...

2016-12-23

The tethering of ligands to nanoparticles has emerged as an important strategy to control interactions and organization in particle assembly structures. Here, we demonstrate that ligand interactions in mixtures of polymer-tethered nanoparticles (which are modified with distinct types of polymer chains) can impart upper or lower critical solution temperature (UCST/LCST)–type phase behavior on binary particle mixtures in analogy to the phase behavior of the corresponding linear polymer blends. Therefore, cooling (or heating) of polymer-tethered particle blends with appropriate architecture to temperatures below (or above) the UCST (or LCST) results in the organization of the individual particle constituents into monotype microdomainmore » structures. The shape (bicontinuous or island-type) and lengthscale of particle microdomains can be tuned by variation of the composition and thermal process conditions. Thermal cycling of LCST particle brush blends through the critical temperature enables the reversible growth and dissolution of monoparticle domain structures. The ability to autonomously and reversibly organize multicomponent particle mixtures into monotype microdomain structures could enable transformative advances in the high-throughput fabrication of solid films with tailored and mutable structures and properties that play an important role in a range of nanoparticle-based material technologies.« less

Polymer ligand–induced autonomous sorting and reversible phase separation in binary particle blends

PubMed Central

Schmitt, Michael; Zhang, Jianan; Lee, Jaejun; Lee, Bongjoon; Ning, Xin; Zhang, Ren; Karim, Alamgir; Davis, Robert F.; Matyjaszewski, Krzysztof; Bockstaller, Michael R.

2016-01-01

The tethering of ligands to nanoparticles has emerged as an important strategy to control interactions and organization in particle assembly structures. We demonstrate that ligand interactions in mixtures of polymer-tethered nanoparticles (which are modified with distinct types of polymer chains) can impart upper or lower critical solution temperature (UCST/LCST)–type phase behavior on binary particle mixtures in analogy to the phase behavior of the corresponding linear polymer blends. Therefore, cooling (or heating) of polymer-tethered particle blends with appropriate architecture to temperatures below (or above) the UCST (or LCST) results in the organization of the individual particle constituents into monotype microdomain structures. The shape (bicontinuous or island-type) and lengthscale of particle microdomains can be tuned by variation of the composition and thermal process conditions. Thermal cycling of LCST particle brush blends through the critical temperature enables the reversible growth and dissolution of monoparticle domain structures. The ability to autonomously and reversibly organize multicomponent particle mixtures into monotype microdomain structures could enable transformative advances in the high-throughput fabrication of solid films with tailored and mutable structures and properties that play an important role in a range of nanoparticle-based material technologies. PMID:28028538

Physical-mechanical properties of agar/κ-carrageenan blend film and derived clay nanocomposite film.

PubMed

Rhim, Jong-Whan

2012-12-01

Binary blend films with different mixing ratio of agar and κ-carrageenan were prepared using a solution casting method with and without nanoclay and the effect of their composition on the mechanical, water vapor barrier, and water resistance properties was tested. The tensile strength (TS) of the κ-carrageenan film was greater than that of agar film. The water vapor permeability (WVP) of the agar film was lower than that of κ-carrageenan film, the swelling ratio (SR) and water solubility (WS) of κ-carrageenan film were higher than those of agar film. Each property of the binary blend films varied proportionately depending on the mixing ratio of each component. The XRD result indicated that the nanocomposite with agar/κ-carrageenan/clay (Cloisite(®) Na(+)) was intercalated. Consequently, the mechanical strength, water vapor barrier properties, and water contact angle (CA) were significantly (P < 0.05) improved through nanocomposite formation. © 2012 Institute of Food Technologists®

Mixing-Induced Anisotropic Correlations in Molecular Crystalline Systems: Rationalizing the Behavior of Organic Semiconductor Blends

NASA Astrophysics Data System (ADS)

Broch, Katharina; Aufderheide, Antje; Novak, Jiri; Hinderhofer, Alexander; Gerlach, Alexander; Banerjee, Rupak; Schreiber, Frank

2013-03-01

Binary mixtures of organic semiconductors (OSCs) have recently become an important field of research, as they find applications in opto-electronic devices. In these systems, the mixing (intermixing vs. phase separation) and ordering behavior is crucial, since it affects the optical and electronic properties. We present a comprehensive study of binary mixtures of the three prototypical OSCs pentacene (PEN), perfluoropentacene (PFP) and diindenoperlyene (DIP) in all possible combinations. Using X-ray reflectivity and grazing incidence X-ray diffraction we investigate the stuctural properties of the mixed films as well as their impact on the optical spectra obtained by spectroscopic ellipsometry. For PEN:DIP we find an anisotropic ordering behavior, comparable to that observed in some liquid crystals, which is fundamentally new for OSCs. The influence of sterical compatibility and the strength of the intermolecular interactions on the mixing and ordering behavior in the different blends will be discussed by extending a conventional mean-field model. Finally, we discuss general rules for the targeted preparation of blends of OSCs.

Carbon capture from natural gas using multi-walled CNTs based mixed matrix membranes.

PubMed

Hussain, Abid; Farrukh, Sarah; Hussain, Arshad; Ayoub, Muhammad

2017-12-05

Most of the polymers and their blends, utilized in carbon capture membranes, are costly, but cellulose acetate (CA) being inexpensive is a lucrative choice. In this research, pure and mixed matrix membranes (MMMs) have been fabricated to capture carbon from natural gas. Polyethylene glycol (PEG) has been utilized in the fabrication of membranes to modify the chain flexibility of polymers. Multi-walled carbon nanotubes (MWCNTs) provide mechanical strength, thermal stability, an extra free path for CO 2 molecules and augment CO 2 /CH 4 selectivity. Membranes of pure CA, CA/PEG blend of different PEG concentrations (5%, 10%, 15%) and CA/PEG/MWCNTs blend of 10% PEG with different MWCNTs concentrations (5%, 10%, 15%) were prepared in acetone using solution casting techniques. Fabricated membranes were characterized using SEM, TGA and tensile testing. Permeation results revealed remarkable improvement in CO 2 /CH 4 selectivity. In single gas experiments, CO 2 /CH 4 selectivity is enhanced 8 times for pure membranes containing 10% PEG and 14 times for MMMs containing 10% MWCNTs. In mix gas experiments, the CO 2 /CH 4 selectivity is increased 13 times for 10% PEG and 18 times for MMMs with 10% MWCNTs. Fabricated MMMs have a tensile strength of 13 MPa and are more thermally stable than CA membranes.

Phase Behavior of Binary Blends of AB+AC Block Copolymers with compatible B and C blocks

NASA Astrophysics Data System (ADS)

Pryamitsyn, Victor; Ganesan, Venkat

2012-02-01

Recently the experimental studies of phase behavior of binary blends of PS-b-P2VP and PS-b-PHS demonstrated an interesting effect: blends of symmetric PS-b-P2VP and shorter symmetric (PS-b-PHS) formed cylindrical HEX and spherical BCC phases, while each pure component formed lamellas. The miscibility of P2VP and PHS is caused by the hydrogen bonding between P2VP and PHS,which can be described as a negative Flory ?-parameter between P2VP and PHS. We developed a theory of the microphase segregation of AB+AC blends of diblock copolymers based on strong stretching theory. The main result of our theory is that in the copolymer brush-like layer formed by longer B chain and shorter C chains, the attraction between B and shorter C chains causes relative stretching of short C chains and compression of longer B chains. The latter manifests in an excessive bending force towards the grafting surface (BC|AA interface). Such bending force causes a transition from a symmetric lamella phase to a HEX cylinder or BCC spherical phases with the BC phase being a ``matrix'' component. In a blend of asymmetric BCC sphere forming copolymers (where B and C segments are the minor components), such bending force may unfold BCC spherical phase to a HEX cylinder phase, or even highly uneven lamella phases.

Phase Behavior in Blends of Asymmetrical Polyolefins

NASA Astrophysics Data System (ADS)

Nedoma, Alisyn Jenise

This dissertation presents the most comprehensive study of chi to date for a single pair of homopolymers. Polyisobutylene (component B) and deuterated polybutadiene with 63 % 1,2 addition (component C) were selected for this study because they exhibit a large window of miscibility and may be tailored to cross the spinodal at experimentally accessible temperatures. Binary blends were designed across a range of values for NB/ NC and the composition of the blend, φB, to study the effect of these parameters on the measured value, chi sc. In addition to the strict temperature dependence presumed for chi, this study documented a composition and molecular weight dependence. The empirical expression for chisc, measured using small angle neutron scattering, was three times more dependent on composition then the expression for chi used to predict thermodynamic behavior. Despite this three-fold diminished dependence on φB, the composition-dependent chi profoundly affected the phase behavior of binary blends. A range of values was studied for NB/ NC ≤ 1, and in all cases φB,cirt was found to be < 0.5, in stark contrast to the expectation of Flory-Huggins Theory that φB,crit ≥ 0.5. This effect was shown to result from the combined effects of a composition-dependent chi and N B/NC removed from values of 1. Remarkable agreement was obtained between the predicted phase diagrams and measured phase transitions, over a range of values for NB/ NC and φB, by accounting for the composition and molecular weight dependence of chi. The miscibility of binary B/C blends was used as the basis for designing a diblock copolymer (component A-C) to order immiscible binary blends of polyisobutylene and deuterated polybutadiene with 89 % 1,2 addition (component A). The copolymer comprised one block chemically identical to component C (miscible in component B) and one block chemically identical to component A. This is in contrast to the majority of ternary blend studies which comprise A/B/A-B polymer systems with neutral interactions between each homopolymer and the corresponding block of the diblock copolymer. Ternary A/B/A-C blends exhibit a favorable interaction between the B homopolymer and C block, demonstrated by the miscibility of B/C blends. The A-C diblock copolymer surfactant can produce microstructures when added to A/B blends at much lower concentrations of copolymer than for an analagous A-B copolymer. This dissertation introduces the use of lamellar structure factor that fits scattering profiles unsuitable for the microemulsion fit. In addition, the lamellar fits include as adjustable parameters the size of each microdomain and corresponding interfacial width. These fit values agree quantitatively with independently generated predictions using self-consistent field theory, indicating a broad understanding of the physical parameters that affect thermodynamic behavior in the A/B/A-C system studied. This dissertation presents a study for which the concentration of diblock copolymer was fixed and the composition of the A and B homopolymers was systematically varied across a range of compositions including φA,crit. The experiment corresponded to tracing the copolymer isopleth on a ternary phase prism. Theoretical groups have predicted a rich phase behavior along the isopleth for similar ternary systems, however, the observed phase behavior was quantitatively identical for all blends studied. Self-consistent field theory predictions agreed with fit values of the domain spacing and microdomain widths. There was no discernible correlation between φA and phase behavior. This finding, and that of the study with critical A/B/A-C blends, together suggest that NA/NB correlates strongly with the phase behavior of a blend, while φ A does not. This relationship, captured by mean-field theory, provides a simple method for tuning the phase behavior of polymer nanocomposites without using additional surfactant. (Abstract shortened by UMI.)

Preparation of robust braid-reinforced poly(vinyl chloride) ultrafiltration hollow fiber membrane with antifouling surface and application to filtration of activated sludge solution.

PubMed

Zhou, Zhuang; Rajabzadeh, Saeid; Fang, Lifeng; Miyoshi, Taro; Kakihana, Yuriko; Matsuyama, Hideto

2017-08-01

Braid-reinforced hollow fiber membranes with high mechanical properties and considerable antifouling surface were prepared by blending poly(vinyl chloride) (PVC) with poly(vinyl chloride-co-poly(ethylene glycol) methyl ether methacrylate) (poly(VC-co-PEGMA)) copolymer via non-solvent induced phase separation (NIPS). The tensile strength of the braid-reinforced PVC hollow fiber membranes were significantly larger than those of previously reported various types of PVC hollow fiber membranes. The high interfacial bonding strength indicated the good compatibility between the coating materials and the surface of polyethylene terephthalate (PET)-braid. Owing to the surface segregation phenomena, the membrane surface PEGMA coverage increased upon increasing the poly(VC-co-PEGMA)/PVC blending ratio, resulting in higher hydrophilicities and bovine serum albumin (BSA) repulsion. To compare the fouling properties, membranes with similar PWPs were prepared by adjusting the dope solution composition to eliminate the effect of hydrodynamic conditions on the membrane fouling performance. The blend membranes surface exhibited considerable fouling resistance to the molecular adsorption from both BSA solution and activated sludge solution. In both cases, the flux recovered to almost 80% of the initial flux using only water backflush. Considering their great mechanical properties and antifouling resistance to activated sludge solution, these novel membranes show good potential for application in wastewater treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

Organosilica Membrane with Ionic Liquid Properties for Separation of Toluene/H₂ Mixture.

PubMed

Hirota, Yuichiro; Maeda, Yohei; Yamamoto, Yusuke; Miyamoto, Manabu; Nishiyama, Norikazu

2017-08-03

In this study, we present a new concept in chemically stabilized ionic liquid membranes: an ionic liquid organosilica (ILOS) membrane, which is an organosilica membrane with ionic liquid-like properties. A silylated ionic liquid was used as a precursor for synthesis. The permselectivity, permeation mechanism, and stability of the membrane in the H₂/toluene binary system were then compared with a supported ionic liquid membrane. The membrane showed a superior separation factor of toluene/H₂ (>17,000) in a binary mixture system based on a solution-diffusion mechanism with improved durability over the supported ionic liquid membrane.

Improvement in hemocompatibility of chitosan/soy protein composite membranes by heparinization.

PubMed

Wang, Xiaomei; Shi, Na; Chen, Yan; Li, Chen; Du, Xinshen; Jin, Weihua; Chen, Yun; Chang, Peter R

2012-01-01

To improve the hemocompatibility of chitosan/soy protein isolate composite membranes by heparinization. Chitosan/soy protein isolate membranes (ChS-n, n=0, 10 and 30, corresponding to the soy protein isolate content in the membranes) and heparinized ChS-n membranes (HChS-n) were prepared by blending in dilute HAc/NaAc solution. The hemocompatibility of ChS-n and HChS-n membranes were comparatively evaluated by measuring surface heparin density, blood platelet adhesion, plasma recalcification time (PRT), thrombus formation and hemolysis assay. The surface heparin density analysis showed that heparinized chitosan/SPI soy protein isolate membranes have been successfully prepared by blending. The density of heparin on the surface of HChS-n membranes was in the range of 0.67-1.29 μg/cm2. The results of platelet adhesion measurement showed that the platelet adhesion numbers of HChS-n membranes were lower than those of the corresponding ChS-n membranes. The PRT of the HChS-0, HChS-10 and HChS-30 membranes were around 292, 306 and 295 s, respectively, which were longer than the corresponding ChS-0 (152 s), ChS-10 (204 s) and ChS-30 (273 s) membranes. The hemolysis rate of HChS-n membranes was lower than 1%. The hemocompatibility of ChS membranes could be improved by blending with heparin. Compared with ChS membranes, HChS membranes showed lower platelet adhesion, longer PRT, higher BCI, significant thromboresistivity and a lower hemolysis rate due to the heparinization. This widens the application of chitosan and soy protein-based biomaterials that may come in contact with blood.

Influence of Brij58 on the Characteristic and Performance of PES Membrane for Water Treatment Process

NASA Astrophysics Data System (ADS)

Mukramah; Syawaliah; Mulyati, S.; Arahman, N.

2017-03-01

This study proposes a modification of polyether sulfone (PES) membrane by blending the polymer with a hydrophilic additive of Brij-58. Flat-sheet PES membrane was prepared through a non-solvent induced phase separation (NIPS) method using dimethylformamide (DMF) as a solvent. PES membrane was modified by adding Brij-58 into dope solution at a different concentration, i.e 1, 3, 5, 7, and 10 wt %. The fabricated membranes were characterized by means of Scanning Electron Microscopy (SEM) and Fourier Transform Infra-Red (FTIR) spectroscopy. Filtration performance of membrane was analyzed by using a dead-end module. It is found that the addition of a small amount of Brij into polymer solution brought about the increase of water flux. FT-IR investigation showed that the additive exist on the surface of a blended membrane.

Efficient and Stable Ternary Organic Solar Cells Based on Two Planar Nonfullerene Acceptors with Tunable Crystallinity and Phase Miscibility.

PubMed

Wang, Jialin; Peng, Jiajun; Liu, Xiaoyu; Liang, Ziqi

2017-06-21

Planar perylene diimides (PDIs), when used as nonfullerene acceptors for organic photovoltaics, are constrained by their large π-aggregation in solid state. To tackle this issue, another planar nonfullerene acceptor 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene (ITIC) with weak crystallinity and near-infrared light absorption is introduced into the PTB7-Th:PDI binary blend to fabricate efficient and stable ternary solar cells. We have finely tuned the PDI/ITIC weight ratio to investigate the influences of individual ITIC and PDI on the optical, electronic, and morphological properties of the PTB7-Th:ITIC:PDI ternary blend. Compared to the binary blend, complementary optical absorption is achieved in all ternary blends. More importantly, it is found that ITIC plays a critical role on largely suppressing the PDI aggregates in the PTB7-Th:PDI blend, while PDI aids to form an interpenetrating network morphology to facilitate charge transport in the PTB7-Th:ITIC blend. Consequently, when the PDI/ITIC ratio is 3:7 (w/w), the PTB7-Th:ITIC:PDI based inverted solar cells exhibit the highest power conversion efficiency of 8.64% due to their favorable out-of-plane π-π stacking, finest phase-separation morphology, and highest charge mobility. Remarkably, the optimal cells that are solution-processed in air show the promising efficiency of 7.09%, suggesting good ambient stability of such ternary solar cells.

Neuronal Differentiation Modulated by Polymeric Membrane Properties.

PubMed

Morelli, Sabrina; Piscioneri, Antonella; Drioli, Enrico; De Bartolo, Loredana

2017-01-01

In this study, different collagen-blend membranes were successfully constructed by blending collagen with chitosan (CHT) or poly(lactic-co-glycolic acid) (PLGA) to enhance their properties and thus create new biofunctional materials with great potential use for neuronal tissue engineering and regeneration. Collagen blending strongly affected membrane properties in the following ways: (i) it improved the surface hydrophilicity of both pure CHT and PLGA membranes, (ii) it reduced the stiffness of CHT membranes, but (iii) it did not modify the good mechanical properties of PLGA membranes. Then, we investigated the effect of the different collagen concentrations on the neuronal behavior of the membranes developed. Morphological observations, immunocytochemistry, and morphometric measures demonstrated that the membranes developed, especially CHT/Col30, PLGA, and PLGA/Col1, provided suitable microenvironments for neuronal growth owing to their enhanced properties. The most consistent neuronal differentiation was obtained in neurons cultured on PLGA-based membranes, where a well-developed neuronal network was achieved due to their improved mechanical properties. Our findings suggest that tensile strength and elongation at break are key material parameters that have potential influence on both axonal elongation and neuronal structure and organization, which are of fundamental importance for the maintenance of efficient neuronal growth. Hence, our study has provided new insights regarding the effects of membrane mechanical properties on neuronal behavior, and thus it may help to design and improve novel instructive biomaterials for neuronal tissue engineering. © 2017 S. Karger AG, Basel.

Electrodialytic Transport Properties of Anion-Exchange Membranes Prepared from Poly(vinyl alcohol) and Poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride).

PubMed

Jikihara, Atsushi; Ohashi, Reina; Kakihana, Yuriko; Higa, Mitsuru; Kobayashi, Kenichi

2013-01-02

Random-type anion-exchange membranes (AEMs) have been prepared by blending poly(vinyl alcohol) (PVA) and the random copolymer-type polycation, poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride) at various molar percentages of anion-exchange groups to vinyl alcohol groups, Cpc, and by cross-linking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations, CGA. The characteristics of the random-type AEMs were compared with blend-type AEMs prepared in our previous study. At equal molar percentages of the anion exchange groups, the water content of the random-type AEMs was lower than that of the blend-type AEMs. The effective charge density of the random-type AEMs increased with increasing Cpc and reached a maximum value. Further, the maximum value of the effective charge density increased with increasing CGA. The maximum value of the effective charge density, 0.42 mol/dm3, was obtained for the random-type AEM with Cpc = 4.2 mol % and CGA = 0.15 vol %. A comparison of the random-type and blend-type AEMs with almost the same Cpc showed that the random-type AEMs had lower membrane resistance than the blend-type ones. The membrane resistance and dynamic transport number of the random-type AEM with Cpc = 6.0 mol % and CGA = 0.15 vol % were 4.8 Ω cm2 and 0.83, respectively.

Electrodialytic Transport Properties of Anion-Exchange Membranes Prepared from Poly(vinyl alcohol) and Poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride)

PubMed Central

Jikihara, Atsushi; Ohashi, Reina; Kakihana, Yuriko; Higa, Mitsuru; Kobayashi, Kenichi

2012-01-01

Random-type anion-exchange membranes (AEMs) have been prepared by blending poly(vinyl alcohol) (PVA) and the random copolymer-type polycation, poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride) at various molar percentages of anion-exchange groups to vinyl alcohol groups, Cpc, and by cross-linking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations, CGA. The characteristics of the random-type AEMs were compared with blend-type AEMs prepared in our previous study. At equal molar percentages of the anion exchange groups, the water content of the random-type AEMs was lower than that of the blend-type AEMs. The effective charge density of the random-type AEMs increased with increasing Cpc and reached a maximum value. Further, the maximum value of the effective charge density increased with increasing CGA. The maximum value of the effective charge density, 0.42 mol/dm3, was obtained for the random-type AEM with Cpc = 4.2 mol % and CGA = 0.15 vol %. A comparison of the random-type and blend-type AEMs with almost the same Cpc showed that the random-type AEMs had lower membrane resistance than the blend-type ones. The membrane resistance and dynamic transport number of the random-type AEM with Cpc = 6.0 mol % and CGA = 0.15 vol % were 4.8 Ω cm2 and 0.83, respectively. PMID:24958543

Electrospun fiber membranes enable proliferation of genetically modified cells

PubMed Central

Borjigin, Mandula; Eskridge, Chris; Niamat, Rohina; Strouse, Bryan; Bialk, Pawel; Kmiec, Eric B

2013-01-01

Polycaprolactone (PCL) and its blended composites (chitosan, gelatin, and lecithin) are well-established biomaterials that can enrich cell growth and enable tissue engineering. However, their application in the recovery and proliferation of genetically modified cells has not been studied. In the study reported here, we fabricated PCL-biomaterial blended fiber membranes, characterized them using physicochemical techniques, and used them as templates for the growth of genetically modified HCT116-19 colon cancer cells. Our data show that the blended polymers are highly miscible and form homogenous electrospun fiber membranes of uniform texture. The aligned PCL nanofibers support robust cell growth, yielding a 2.5-fold higher proliferation rate than cells plated on standard plastic plate surfaces. PCL-lecithin fiber membranes yielded a 2.7-fold higher rate of proliferation, while PCL-chitosan supported a more modest growth rate (1.5-fold higher). Surprisingly, PCL-gelatin did not enhance cell proliferation when compared to the rate of cell growth on plastic surfaces. PMID:23467983

Preparation and electrochemical characterization of polymer electrolytes based on electrospun poly(vinylidene fluoride- co-hexafluoropropylene)/polyacrylonitrile blend/composite membranes for lithium batteries

NASA Astrophysics Data System (ADS)

Raghavan, Prasanth; Zhao, Xiaohui; Shin, Chorong; Baek, Dong-Ho; Choi, Jae-Won; Manuel, James; Heo, Min-Yeong; Ahn, Jou-Hyeon; Nah, Changwoon

Apart from PEO based solid polymer electrolytes, tailor-made gel polymer electrolytes based on blend/composite membranes of poly(vinylidene fluoride- co-hexafluoropropylene) and polyacrylonitrile are prepared by electrospinning using 14 wt% polymer solution in dimethylformamide. The membranes show uniform morphology with an average fiber diameter of 320-490 nm, high porosity and electrolyte uptake. Polymer electrolytes are prepared by soaking the electrospun membranes in 1 M lithium hexafluorophosphate in ethylene carbonate/dimethyl carbonate. Temperature dependent ionic conductivity and their electrochemical performance are studied. The blend/composite polymer electrolytes show good ionic conductivity in the range of 10 -3 S cm -1 at ambient temperature and good electrochemical performance. All the Polymer electrolytes show an anodic stability >4.6 V with stable interfacial resistance with storage time. The prototype cell shows good charge-discharge properties and stable cycle performance with comparable capacity fade compared to liquid electrolyte under the test conditions.

The ‘ideal selectivity’ vs ‘true selectivity’ for permeation of gas mixture in nanoporous membranes

NASA Astrophysics Data System (ADS)

He, Zhou; Wang, Kean

2018-03-01

In this study, we proposed and validated a novel and non-destructive experimental technology for measuring the permeation of binary gas mixture in nanoporous membranes. The traditional time lag rig was modified to examine the permeation characteristics of each gas component as well as that of the binary gas mixtures. The difference in boiling points of each species were explored. Binary gas mixtures of CO2/He were permeated through the nanoporous carbon molecular sieve membrane (CMSM). The results showed that, due to the strong interaction among different molecules and with the porous network of the membrane, the measured perm-selectivity or ‘true selectivity’ of a binary mixture can significantly deviate from the ‘ideal selectivity’ calculated form the permeation flux of each pure species, and this deviation is a complicated function of the molecular properties and operation conditions.

A nitrogen-doped carbon nanotube enhanced polyethersulfone membrane system for water treatment

NASA Astrophysics Data System (ADS)

Phao, Neo; Nxumalo, Edward N.; Mamba, Bhekie B.; Mhlanga, Sabelo D.

Water quality in South Africa and around the world continues to deteriorate due to contamination by organic, inorganic and microbial substances. While many efforts have been done to address water quality problems, current drinking water treatment technologies remain costly and do not effectively remove pollutants to acceptable levels. In this work nitrogen doped carbon nanotubes/polyethersulfone (N-CNT/PES) blend membranes were synthesized via a modified phase inversion method and assessed for suitability in drinking water treatment. The N-CNTs with outer diameters of 30-45 nm and 3% N content were prepared using a conventional chemical vapour deposition method and functionalized by refluxing in HNO3. The confirmation and degree of functionalization with -OH and -COOH groups was determined using Fourier-transform infrared (FTIR) spectroscopy and zeta potential analysis. FTIR studies confirmed the successful incorporation of functionalized N-CNTs (N-CNTs) in the membrane matrix. Atomic force microscopy (AFM) analysis revealed that the addition of N-CNTs leads to reduced surface roughness, suggesting a good dispersion of the N-CNTs in the matrix. Permeability studies revealed that the addition of N-CNTs to the polyethersulfone (PES) solution increased the water flux of the blend membrane by up to 70%. N-CNT loadings of 0.04 wt% in the blend membranes gave low surface contact angle of 55° and high fluxes. In addition, inclusion of N-CNTs enhanced the mechanical properties of the N-CNT/PES blend membranes. The use of N-CNTs in mixed matrix PES membranes is reported for the first time here. The result already suggests superior compatibility of the N-CNTs with PES compared to undoped CNTs, due to the high surface reactivity of the N-CNTs.

Formulating a low-alkalinity, high-resistance and low-heat concrete for radioactive waste repositories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cau Dit Coumes, Celine; Courtois, Simone; Nectoux, Didier

2006-12-15

Investigations were carried out in order to formulate and characterize low-alkalinity and low-heat cements which would be compatible with an underground waste repository environment. Several systems comprising Ordinary Portland Cement (OPC), a fast-reacting pozzolan (silica fume (SF) or metakaolin (MK)) and, in some cases, a slow-reacting product (fly ash (FA) or blastfurnace slag (BFS)) were compared. Promising results were obtained with some binary mixtures of OPC and SF, and with some ternary blends of OPC, SF and FA or BFS: pH of water in equilibrium with the fully hydrated cements dropped below 11. Dependence of the properties of standard mortarsmore » on the high contents of FA and SF in the low-pH blends was examined. Combining SF and FA seemed attractive since SF compensated for the low reactivity of FA, while FA allowed to reduce the water demand, and dimensional variations of the mortars. Finally, low-heat ({delta}T < 20 deg. C under semi-adiabatic conditions) and high strength ({approx} 70-80 MPa) concretes were prepared from two low-pH cements: a binary blend made from 60% of OPC and 40% of SF, and a ternary blend including 37.5% OPC, 32.5% SF and 30% FA.« less

Clinical characterization of a new polymeric membrane for use in renal replacement therapy.

PubMed

Hoenich, Nicholas A; Katopodis, Kostas P

2002-09-01

Renal replacement therapy makes extensive use of semi-permeable membranes, ideal requirements for such membranes are good solute transport characteristics and a low reactivity with blood. Membranes manufactured from synthetic polymers fulfil these requirements. Such membranes have asymmetric and anisotropic structures characterized by a dense layer with which the blood is in contact supported by a thicker solid structure with containing interlinked voids, providing support. The nature of the structures are critically dependent upon the polymer blend and the control of parameters during manufacture such as the temperature or additive concentrations. In this prospective study, we have evaluated the clinical performance of a new membrane manufactured from a blend of polyamide, polyarylethersulfone and polyvinylpyrrolidone (Polyflux, Gambro GmbH, Hechingen, Germany), and compared it with that of polysulfone blended with polyvinylpyrrolidone (Fresenius Polysulfone, Fresenius Medical Care, Bad Homburg, Germany), a material widely acknowledged as providing an optimal biocompatibility in terms of solute removal and complement activation. The clearance of small molecules (urea, creatinine, phosphate) for both membranes was comparable. Both membranes removed beta2 microglobulin during treatment (50.2% reduction with Polyflux and 54.5% reduction with polysulfone. This removal due to the non-selectivity of the membranes was associated with protein loss during therapy which was similar for both the membranes (7.7 g). The biocompatibility profiles of the membranes indicated slight neutropenia and platelet adhesion and minimal C3a, C5a and SC5b-9 generation which were independent of the membrane material. These findings indicate that despite the differences in microstructure of the membranes, their functional performance in the clinical setting is comparable.

OGLE-2015-BLG-0479LA,B: BINARY GRAVITATIONAL MICROLENS CHARACTERIZED BY SIMULTANEOUS GROUND-BASED AND SPACE-BASED OBSERVATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, C.; Udalski, A.; Szymański, M. K.

2016-09-01

We present a combined analysis of the observations of the gravitational microlensing event OGLE-2015-BLG-0479 taken both from the ground and by the Spitzer Space Telescope . The light curves seen from the ground and from space exhibit a time offset of ∼13 days between the caustic spikes, indicating that the relative lens-source positions seen from the two places are displaced by parallax effects. From modeling the light curves, we measure the space-based microlens parallax. Combined with the angular Einstein radius measured by analyzing the caustic crossings, we determine the mass and distance of the lens. We find that the lensmore » is a binary composed of two G-type stars with masses of ∼1.0 M {sub ⊙} and ∼0.9 M {sub ⊙} located at a distance of ∼3 kpc. In addition, we are able to constrain the complete orbital parameters of the lens thanks to the precise measurement of the microlens parallax derived from the joint analysis. In contrast to the binary event OGLE-2014-BLG-1050, which was also observed by Spitzer, we find that the interpretation of OGLE-2015-BLG-0479 does not suffer from the degeneracy between (±, ±) and (±, ∓) solutions, confirming that the four-fold parallax degeneracy in single-lens events collapses into the two-fold degeneracy for the general case of binary-lens events. The location of the blend in the color–magnitude diagram is consistent with the lens properties, suggesting that the blend is the lens itself. The blend is bright enough for spectroscopy and thus this possibility can be checked from future follow-up observations.« less

Preparation, characterisation and critical flux determination of graphene oxide blended polysulfone (PSf) membranes in an MBR system.

PubMed

Ravishankar, Harish; Roddick, Felicity; Navaratna, Dimuth; Jegatheesan, Veeriah

2018-05-01

Microfiltration membranes having different blends of graphene-oxide (GO) (0-1 wt%) and Polysulfone (PSf) (15-20 wt%) were prepared using the classical non-solvent induced phase inversion process. The prepared membranes were characterised for their structural morphology, surface properties, mechanical strength, porosity and pure water flux. Based on the initial characterisation results, four membranes (15 wt% PSf, 15 wt% PSf + 0.25 wt% GO, 15 wt% PSf + 1 wt% GO and 20 wt% PSf + 1 wt% GO) were chosen for critical flux study, that was conducted using flux-step method in a lab scale MBR system. In order to study the application potential of GO blended membranes, the critical flux of each membrane was evaluated in two operational modes i.e., continuous and intermittent modes with backwash. The membranes with maximal GO concentration (15 wt% PSf + 1 wt% GO and 20 wt% PSf + 1 wt% GO) showed higher critical flux (16.5, 12.8 L/m 2 h and 19, 15 L/m 2 h for continuous and intermittent mode, respectively). It was observed that the operational modes did not have a significant effect on the critical flux of the membranes with low GO concentration (15 wt% PSf and 15 wt% PSf + 0.25 wt% GO), indicating a minimal of 1 wt% GO was required for an observable effect that favoured intermittent mode of operation. Through these results, ideal operating condition was arrived (i.e., flux maintained at 6.4 L/m 2 h operated under intermittent mode) and the membranes 15 wt% PSf and 15 wt% PSf + 1 wt% GO were studied for their long-term operation. The positive effect of GO on filtration time, cleaning frequency and against fouling was demonstrated through long term TMP profile of the membranes, indicating the suitability of GO blended membrane for real time wastewater treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Preparation of Low fouling Polyethersulfone Membranes by Simultaneously Phase Separation and Redox Polymerization

NASA Astrophysics Data System (ADS)

Roihatin, A.; Susanto, H.

2017-05-01

This paper presents preparation of low fouling PES membranes by non solvent induced phase separation (NIPS) coupled with redox polymerization. The membrane characterization included water permeability, morphology structure (by SEM) and surface chemistry (by FTIR). Water permeability measurements showed thatthe membranes have water permeability within the range 10-50 L/h.m2.bar. Addition of PEG dan PEGMA intopolymer solution increased water permeability, whereas blending redox initiator and crosslinker, MBAA in polymer solution decreased water permeability. Surface morfology of membranes by SEM showed that unmodified PES membrane had smaller pore size than PEG or PEGMA modified PES membranes. Furthermore, PES-PEG or PES-PEGMA membranes modified by blending with redox initiator and MBAA as crosslinker showed smaller pore size than unmodified membrane. FTIR analysis showed that all membranes have typical spectraof PES polymer; however no additional peak was observed forthe membranes prepared with addition of PEG/PEGMA, initiator redox and also crosslinker. The addition of PEG/PEGMA, redox initiator and crosslinker resulted in membranes with high rejection and an acceptable flux as well as more stable due to relatively high fouling resistance.

Improvement of electrochemical performances of sulfonated poly(arylene ether sulfone) via incorporation of sulfonated poly(arylene ether benzimidazole)

NASA Astrophysics Data System (ADS)

Hong, Young Taik; Lee, Chang Hyun; Park, Hyung Su; Min, Kyung A.; Kim, Hyung Joong; Nam, Sang Yong; Lee, Young Moo

In the present study, modified acid-base blend membranes were fabricated via incorporation of sulfonated poly(arylene ether benzimidazole) (SPAEBI) into sulfonated poly(arylene ether sulfone) (SPAES). These membranes had excellent methanol-barrier properties in addition to an ability to compensate for the loss of proton conductivity that typically occurs in general acid-base blend system. To fabricate the membranes, SPAEBIs, which served as amphiphilic polymers with different degrees of sulfonation (0-50 mol%), were synthesized by polycondensation and added to SPAES. It resulted in the formation of acid-amphiphilic complexes such as [PAES-SO 3] - +[H-SPAEBI] through the ionic crosslinking, which prevented SO 3H groups in the complex from transporting free protons in an aqueous medium, contributing to a reduction of ion exchange capacity values and water uptake in the blend membranes, and leading to lower methanol permeability in a water-methanol mixture. Unfortunately, the ionic bonding formation was accompanied by a decrease of bound water content and proton conductivity, although the latter problem was solved to some extent by the incorporation of additional SO 3H groups in SPAEBI. In the SPAES-SPAEBI blend membranes, enhancement of proton conductivity and methanol-barrier property was prominent at temperatures over 90 °C. The direct methanol fuel cell (DMFC) performance, which was based on SPAES-SPAEBI-50-5, was 1.2 times higher than that of Nafion ® 117 under the same operating condition.

Gyroid Structures at Highly Asymmetric Volume Fractions by Blending of ABC Triblock Terpolymer and AB Diblock Copolymer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahn, Seonghyeon; Kwak, Jongheon; Choi, Chungryong

Here, we investigated, via small angle X-ray scattering and transmission electron microscopy, the morphologies of binary blend of polyisoprene- b-polystyrene- b-poly(2-vinylpyridine) (ISP) triblock terpolymer and polyisoprene-b-polystyrene (IS) diblock copolymer. An asymmetric ISP with volume fractions ( f) of 0.12, 0.75, and 0.13 for PI, PS, and P2VP blocks, respectively, showed a new morphology: Coexistence of spheres and cylinders with tetragonal packing. Asymmetric IS with f I = 0.11 and f S =0.89 showed conventional body-centered cubic spherical microdomains. Very interestingly, a binary blend of ISP and IS with overall volume fractions of f I = 0.12, f S = 0.79,more » and f P = 0.09 exhibited core-shell double gyroid (CSG: Q 230 space group), where PI consists of thin core and PS forms thick shell, while P2VP becomes thin matrix. It is very unusual to form highly asymmetric CSG with the matrix having very small volume fraction (0.09).« less

Gyroid Structures at Highly Asymmetric Volume Fractions by Blending of ABC Triblock Terpolymer and AB Diblock Copolymer

DOE PAGES

Ahn, Seonghyeon; Kwak, Jongheon; Choi, Chungryong; ...

2017-11-08

Here, we investigated, via small angle X-ray scattering and transmission electron microscopy, the morphologies of binary blend of polyisoprene- b-polystyrene- b-poly(2-vinylpyridine) (ISP) triblock terpolymer and polyisoprene-b-polystyrene (IS) diblock copolymer. An asymmetric ISP with volume fractions ( f) of 0.12, 0.75, and 0.13 for PI, PS, and P2VP blocks, respectively, showed a new morphology: Coexistence of spheres and cylinders with tetragonal packing. Asymmetric IS with f I = 0.11 and f S =0.89 showed conventional body-centered cubic spherical microdomains. Very interestingly, a binary blend of ISP and IS with overall volume fractions of f I = 0.12, f S = 0.79,more » and f P = 0.09 exhibited core-shell double gyroid (CSG: Q 230 space group), where PI consists of thin core and PS forms thick shell, while P2VP becomes thin matrix. It is very unusual to form highly asymmetric CSG with the matrix having very small volume fraction (0.09).« less

Production of silk sericin/silk fibroin blend nanofibers

NASA Astrophysics Data System (ADS)

Zhang, Xianhua; Tsukada, Masuhiro; Morikawa, Hideaki; Aojima, Kazuki; Zhang, Guangyu; Miura, Mikihiko

2011-08-01

Silk sericin (SS)/silk fibroin (SF) blend nanofibers have been produced by electrospinning in a binary SS/SF trifluoroacetic acid (TFA) solution system, which was prepared by mixing 20 wt.% SS TFA solution and 10 wt.% SF TFA solution to give different compositions. The diameters of the SS/SF nanofibers ranged from 33 to 837 nm, and they showed a round cross section. The surface of the SS/SF nanofibers was smooth, and the fibers possessed a bead-free structure. The average diameters of the SS/SF (75/25, 50/50, and 25/75) blend nanofibers were much thicker than that of SS and SF nanofibers. The SS/SF (100/0, 75/25, and 50/50) blend nanofibers were easily dissolved in water, while the SS/SF (25/75 and 0/100) blend nanofibers could not be completely dissolved in water. The SS/SF blend nanofibers could not be completely dissolved in methanol. The SS/SF blend nanofibers were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, and differential thermal analysis. FTIR showed that the SS/SF blend nanofibers possessed a random coil conformation and ß-sheet structure.

Physical properties and biocompatibility of chitosan/soy blended membranes.

PubMed

Silva, S S; Santos, M I; Coutinho, O P; Mano, J F; Reis, R L

2005-06-01

Blends of polysaccharides and proteins are a source for the development of novel materials with interesting and tailorable properties, with potential to be used in a range of biomedical applications. in this work a series of blended membranes composed by chitosan and soy protein isolate was prepared by solvent casting methodology. in addition, cross-linking was performed in situ with glutaraldehyde solutions in the range 5x10(-3)-0.1 M. Furthermore, the influence of the composition and cross-linking on the degradation behaviour, water uptake and cell adhesion was investigated. The obtained results showed that the incorporation of chitosan, associated to network formation by cross linking, promoted a slight decrease of water absorption and a slower degradability of the membranes. Moreover, direct contact biocompatibility studies, with L929 cells, indicate that the cross-linking enhances the capability of the material to support cell growth.

Preparation of hydrophilic PVDF/PPTA blend membranes by in situ polycondensation and its application in the treatment of landfill leachate

NASA Astrophysics Data System (ADS)

Li, Hongbin; Shi, Wenying; Zhang, Yufeng; Zhou, Rong; Zhang, Haixia

2015-08-01

High modulus poly(p-phenylene terephtalamide) (PPTA) reinforced composites are of great scientific interests. But the thermodynamic difference makes the polymer pairs incompatible and endows the composites with inferior physical-chemical properties. In this study, hydrophilic poly(vinylidene fluoride) (PVDF)/poly(p-phenylene terephtalamide) (PPTA) blend membrane with improved hydrophilicity and mechanical strength was prepared through in situ polycondensation of p-phenylene diamine (PPD) and terephthaloyl chloride (TPC) in PVDF solution and subsequent immersion precipitation phase inversion process. The effects of PPTA concentration in polymer dopes on membrane formation process, structure, morphology and performance were systematically investigated. The results showed that thermodynamically, PPTA acted as a demixing enhancer which accelerated the phase inversion process. Dynamically, liquid-liquid phase separation was still in control of membrane formation process especially in the later period, whereas the addition of PPTA mainly promoted the early emergence of the liquid-liquid demixing. The surface hydrophilicity, ant-fouling properties and mechanical strength were significantly improved when PPTA content was 17 wt%. When PPTA content increased to 26 wt%, membrane bursting pressure increased to nearly 0.6 MPa which was 1.5 times higher than that of PVDF membrane. The resultant PVDF/PPTA blend membrane exhibited an improved antifouling property than that of PVDF membrane when applied in the MBR in the treatment of landfill leachate and also showed a relatively high removal rate of chemical oxygen demand (COD) and chrom.

Hydrophilicity improvement in polyphenylsulfone nanofibrous filtration membranes through addition of polyethylene glycol

NASA Astrophysics Data System (ADS)

Kiani, Shirin; Mousavi, Seyed Mahmoud; Shahtahmassebi, Nasser; Saljoughi, Ehsan

2015-12-01

Novel hydrophilic polyphenylsulfone (PPSU) nanofibrous membrane was prepared by electrospinning of the PPSU solution blended with polyethylene glycol 400 (PEG 400). The influence of the PEG concentration on the membrane characteristics was studied using scanning electron microscopy (SEM), water contact angle measurement, and tensile test. Filtration performance of the membranes was investigated by measurement of pure water flux (PWF) and determination of the rejection values of the pollution indices during treatment of canned beans production wastewater. According to the results, blending the PPSU solution with 10 wt.% PEG 400 resulted in formation of a nanofibrous membrane with high porosity and increased mechanical strength which exhibited a low water contact angle of 8.9° and high water flux of 7920 L/m2h. Flux recovery of the mentioned membrane which was assessed by filtration of a solution containing bovine serum albumin (BSA) was 83% indicating a noticeable antifouling property.

Tailoring the mechanical and biodegradable properties of binary blends of biomedical thermoplastic elastomer.

PubMed

Ang, Hui Ying; Chan, Jingni; Toong, Daniel; Venkatraman, Subbu S; Chia, Sing Joo; Huang, Ying Ying

2018-03-01

Blending polymers with complementary properties capitalizes on the inherent advantages of both components, making it possible to tailor the behaviour of the resultant material. A polymer blend consisting of an elastomer and thermoplastic can help to improve the mechanical integrity of the system without compromising on its processibility. A series of blends of biodegradable Poly(L-lactide-co-ɛ-caprolactone) (PLC) and Poly-(l,l-lactide-co-glycolic acid) (PLLGA), and PLC with Poly-(d,l-lactide-co-glycolic acid) (PDLLGA) were evaluated as a potential material for a biodegradable vesicourethral connector device. Based on the Tg of the blends, PLC/PLLGA formed an immiscible mixture while PLC/PDLLGA resulted in a compatible blend. The results showed that with the blending of PLC, the failure mode of PLLGA and PDLLGA changed from brittle to ductile fracture, with an significant decreas in tensile modulus and strength. SEM images demonstrated the different blend morphologies of different compositions during degradation. Gel Permeation Chromatography (GPC) and mechanical characterization revealed the degradation behaviour of the blends in this order (fastest to slowest): PDLLGA and PLC/PDLLGA blends > PLLGA and PLC/PLLGA blends > PLC. The PLC/PLLGA (70:30) blend was recommended as a suitable for the vesicourethral connector device application, highlighting the tailoring of blends to achieve a desired mechanical performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dynamic filtration and static adsorption of lead ions in aqueous solution by use of blended polysulfone membranes with nano size MCM-41 particles coated by polyaniline.

PubMed

Toosi, Mohammad Reza; Emami, Mohammad Reza Sarmasti; Hajian, Sudeh

2018-05-11

MCM-41 mesopore was prepared by hydrothermal method and used for synthesis of polyaniline/MCM-41 nanocomposite via in situ polymerization. The nanocomposite was blended with polysulfone to prepare mixed matrix membrane in different content of nanocomposite by phase inversion method. Structural and surface properties of the samples were characterized by SEM, XRD, FTIR, AFM, TGA, BET, and zeta potential measurements. Effect of the nanocomposite content on the hydrophilicity, porosity, and permeability of the membrane was determined. Membrane performance was evaluated for removal of lead ions in dynamic filtration and static adsorption. The membranes were found as effective adsorptive filters for removal of lead ions via interactions between active sites of nanocomposite in membrane structure and lead ions during filtration. Results of batch experiments proved adsorptive mechanism of membranes for removal of lead ions with the maximum adsorption capacity of 19.6 mg/g.

Characterization of layered silicate-reinforced blends of thermoplastic starch (TPS) and poly(butylene adipate-co-terephthalate).

PubMed

Lendvai, László; Apostolov, Anton; Karger-Kocsis, József

2017-10-01

A two-step melt blending procedure was used to produce binary systems composed of thermoplastic starch (TPS) and poly(butylene adipate-co-terephthalate) (PBAT). To improve the properties of the blends, two different layered silicates, viz. bentonite (BT) and organically modified montmorillonite (oMMT) were incorporated. First, TPS and its layered silicate nanocomposites were prepared via extrusion compounding during which starch was plasticized with glycerol and water. In the second step, PBAT was added to TPS/layered silicate to produce blends in a batch-type mixer. Mechanical and thermal properties were determined. The blends showed acceptable ductility over 50wt.% PBAT content, although at the cost of strength and stiffness. By contrast to oMMT the BT became intercalated in TPS and TPS/PBAT blends. The reinforcing effect of BT and oMMT was most prominent for the glassy states of both TPS and TPS/PBAT blends. Thermal, and thermooxidative properties were not significantly affected by the presence of layered silicates. Copyright © 2017 Elsevier Ltd. All rights reserved.

Topological and morphological analysis of gamma rays irradiated chitosan-poly (vinyl alcohol) blends using atomic force microscopy

NASA Astrophysics Data System (ADS)

Bhatt, Rinkesh; Bisen, D. S.; Bajpai, R.; Bajpai, A. K.

2017-04-01

In the present communication, binary blends of poly (vinyl alcohol) (PVA) and chitosan (CS) were prepared by solution cast method and the roughness parameters of PVA, native CS and CS-PVA blend films were determined using atomic force microscopy (AFM). Moreover, the changes in the morphology of the samples were also investigated after irradiation of gamma rays at absorbed dose of 1 Mrad and 10 Mrad for the scanning areas of 5×5 μm2, 10×10 μm2 and 20×20 μm2. Amplitude, statistical and spatial parameters, including line, 3D and 2D image profiles of the experimental surfaces were examined and compared to un-irradiated samples. For gamma irradiated CS-PVA blends the larger waviness over the surface was found as compared to un-irradiated CS-PVA blends but the values of average roughness for both the films were found almost same. The coefficient of skewness was positive for gamma irradiated CS-PVA blends which revealed the presence of more peaks than valleys on the blend surfaces.

Ternary Blend Composed of Two Organic Donors and One Acceptor for Active Layer of High-Performance Organic Solar Cells.

PubMed

Lee, Jong Won; Choi, Yoon Suk; Ahn, Hyungju; Jo, Won Ho

2016-05-04

Ternary blends composed of two donor absorbers with complementary absorptions provide an opportunity to enhance the short-circuit current and thus the power conversion efficiency (PCE) of organic solar cells. In addition to complementary absorption of two donors, ternary blends may exhibit favorable morphology for high-performance solar cells when one chooses properly the donor pair. For this purpose, we develop a ternary blend with two donors (diketopyrrolopyrrole-based polymer (PTDPP2T) and small molecule ((TDPP)2Ph)) and one acceptor (PC71BM). The solar cell made of a ternary blend with 10 wt % (TDPP)2Ph exhibits higher PCE of 7.49% as compared with the solar cells with binary blends, PTDPP2T:PC71BM (6.58%) and (TDPP)2Ph:PC71BM (3.21%). The higher PCE of the ternary blend solar cell is attributed mainly to complementary absorption of two donors. However, a further increase in (TDPP)2Ph content in the ternary blend (>10 wt %) decreases the PCE. The ternary blend with 10 wt % (TDPP)2Ph exhibits well-developed morphology with narrow-sized fibrils while the blend with 15 wt % (TDPP)2Ph shows phase separation with large-sized domains, demonstrating that the phase morphology and compatibility of ternary blend are important factors to achieve a high-performance solar cell made of ternary blends.

Preparation, characterization, physical testing and performance of flurocarbon membranes and separators

NASA Technical Reports Server (NTRS)

Lagow, R. J.; Dumitru, E. T.

1983-01-01

The direct fluorination method of converting carefully selected hydrocarbon substrates to fluorinated membranes was successfully applied to produce promising, novel membranes for electrochemical devices. A family of polymer blends was identified which permits wide latitude in the concentration of both crosslinks and carboxyl groups in hydrocarbon membranes. The membranes of paragraph two were successfully fluorinated.

Chain confinement, phase transitions, and lamellar structure in semicrystalline polymers, polymer blends and polymer nanocomposites

NASA Astrophysics Data System (ADS)

Chen, Huipeng

Recent studies suggest that there are three phase fractions in semicrystalline polymers, the crystalline, the mobile amorphous and the rigid amorphous phases. Due to the distinct properties of the rigid amorphous fraction, RAF, it has been investigated for more than twenty years. In this thesis, a general method using quasi-isothermal temperature-modulated differential scaning calorimetry, DSC, is provided for the first time to obtain the temperature dependent RAF and the other two fractions, crystalline fraction and mobile amorphous fraction, MAF. For poly(ethylene terephthalate), PET, our results show RAF was vitrified during quasi-isothermal cooling after crystallization had been completed and became totally devitrified during quasi-isothermal heating before the start of melting. Several years after people initially discovered the existence of RAF, another issue arose relating to the physical location of RAF and mobile amorphous fraction, MAF, within a lamellar stack model. Two very different models to describe the location of RAF were proposed. In the Heterogeneous Stack Model, HET, RAF is located outside the lamellar stacks. In the Homogeneous Stack Model, HSM, RAF was located inside the lamellar stacks. To determine the lamellar structure of semicrystalline polymers comprising three phase, a general method is given in this thesis by using a combination of the DSC and small angle X-ray scattering, SAXS techniques. It has been applied to Nylon 6, isotactic polystyrene, iPS, and PET. It was found for all of these materials, the HSM model is correct to describe the lamellar structure. In addition to the determination of lamellar structures, this method can also provide the exact fraction of MAF inside and outside lamellar stacks for binary polymer blends. For binary polymer blends, MAF, normally is located partially inside and partially outside the lamellar stacks. However, the quantification of the MAF inside and outside the lamellar stacks has now been provided and is applied to the iPS/atactic polystyrene, aPS, blends. The fractions of MAF inside and outside the lamellar stacks were quantified for the first time. For A/B binary polymer blends, it has been reported that if B is already crystalline, the crystalline fraction would serve as a restriction on the subsequent growth of the crystallizable partner A, while amorphous fraction could be diffused from the crystalline growth front of the crystallizing A component. Considering the effect of RAF on binary blends, a new concept is provided: like the crystals, the RAF of one polymer component may inhibit the growth of crystals of the other blend partner. The non-isothermal crystallization of PET/poly(lactic acid), PLA, blends were investigated and the results confirmed the new concept is correct: PET forms a large amount of RAF and inhibits crystal formation in PLA. Then, we broadened the concept of RAF and investigated the RAF in recent 'hot' materials, polymer nanocomposites. It was found the fraction of RAF greatly increased with a small amount of multi-wall carbon nanotubes, MWCNT, loading in PET electrospun, ES, fibers. A general model is given for polymer ES fibers with MWCNTs: the addition of MWCNTs causes polymer chains in the ES fibers to become more extended, (ie, more stretched), resulting in more confinement of PET chains and an increase in the RAF.

Production of silk sericin/silk fibroin blend nanofibers

PubMed Central

2011-01-01

Silk sericin (SS)/silk fibroin (SF) blend nanofibers have been produced by electrospinning in a binary SS/SF trifluoroacetic acid (TFA) solution system, which was prepared by mixing 20 wt.% SS TFA solution and 10 wt.% SF TFA solution to give different compositions. The diameters of the SS/SF nanofibers ranged from 33 to 837 nm, and they showed a round cross section. The surface of the SS/SF nanofibers was smooth, and the fibers possessed a bead-free structure. The average diameters of the SS/SF (75/25, 50/50, and 25/75) blend nanofibers were much thicker than that of SS and SF nanofibers. The SS/SF (100/0, 75/25, and 50/50) blend nanofibers were easily dissolved in water, while the SS/SF (25/75 and 0/100) blend nanofibers could not be completely dissolved in water. The SS/SF blend nanofibers could not be completely dissolved in methanol. The SS/SF blend nanofibers were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, and differential thermal analysis. FTIR showed that the SS/SF blend nanofibers possessed a random coil conformation and ß-sheet structure. PMID:21867508

Preparation and Analysis of Co-precipitated, Biodegradable Poly-(Lactide-co-Glycolide) and Polyethylene Glycol Microspheres Prepared by Spray Drying

NASA Astrophysics Data System (ADS)

Javiya, Curie

Biodegradable poly-(d,l-lactide-co-glycolide) (PLGA) based microspheres are commonly used for numerous clinical applications. PEG is a widely used polymer due to its hydrophilic, biocompatible, and nontoxic nature. In this study, different blends of PLGA/PEG microspheres were prepared using a spray drying technique. The microspheres were spherical with maximum yield found to be 60.3% and average particle size in the range of 2.4 to 3.1 microm. Under the spray drying processing conditions, the polymers showed full miscibility slightly below 15% w/w and partial miscibility up to 20% w/w of PEG in the blended microspheres. At higher temperatures, PLGA and PEG were miscible in all proportions used for the blended microspheres. Blending 10% w/w PEG in PLGA membranes showed significant reduction in attachment of macrophages compared to PLGA membranes. The in-vitro response of macrophage towards the miscible blends of PLGA/PEG microspheres was further characterized. Results showed some reduction in macrophage viability and activation, however, significant effects with PLGA/PEG microspheres were not observed.

Synthesis and characterization of sulfonate polystyrene-lignosulfonate-alumina (SPS-LS-Al{sub 2}O{sub 3}) polyblends as electrolyte membranes for fuel cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonggo, Siang Tandi, E-mail: standigonggo@yahoo.com

2015-09-30

The new type of electrolyte membrane materials has been prepared by blend sulfonated polystyrene (SPS), lignosulfonate (LS), and alumina (SPS-LS-Al{sub 2}O{sub 3}) by casting polymer solution. The resulting polymer electrolyte membranes were then characterized by functional groups analysis, mechanical properties, water uptake, ion exchange capacity, and proton conductivity. SPS-LS-Al{sub 2}O{sub 3} membranes with alumina composition various have been proven qualitatively by analysis of functional groups. Increasing the Al{sub 2}O{sub 3} ratio resulted in higher ion exchange capacity (IEC), mechanical strength and proton conductivity, but water uptake decreased. The SPS-LS-Al{sub 2}O{sub 3} blend showed higher proton conductivity than Nafion 117.

Differential regulation of fatty acid biosynthesis in two Chlorella species in response to nitrate treatments and the potential of binary blending microalgae oils for biodiesel application.

PubMed

Cha, Thye San; Chen, Jian Woon; Goh, Eng Giap; Aziz, Ahmad; Loh, Saw Hong

2011-11-01

This study was undertaken to investigate the effects of different nitrate concentrations in culture medium on oil content and fatty acid composition of Chlorella vulgaris (UMT-M1) and Chlorella sorokiniana (KS-MB2). Results showed that both species produced significant higher (p<0.05) oil content at nitrate ranging from 0.18 to 0.66 mM with C. vulgaris produced 10.20-11.34% dw, while C. sorokiniana produced 15.44-17.32% dw. The major fatty acids detected include C16:0, C18:0, C18:1, C18:2 and C18:3. It is interesting to note that both species displayed differentially regulated fatty acid accumulation patterns in response to nitrate treatments at early stationary growth phase. Their potential use for biodiesel application could be enhanced by exploring the concept of binary blending of the two microalgae oils using developed mathematical equations to calculate the oil mass blending ratio and simultaneously estimated the weight percentage (wt.%) of desirable fatty acid compositions. Copyright © 2011 Elsevier Ltd. All rights reserved.

Large animal in vivo evaluation of a binary blend polymer scaffold for skeletal tissue-engineering strategies; translational issues.

PubMed

Smith, James O; Tayton, Edward R; Khan, Ferdous; Aarvold, Alexander; Cook, Richard B; Goodship, Allen; Bradley, Mark; Oreffo, Richard O C

2017-04-01

Binary blend polymers offer the opportunity to combine different desirable properties into a single scaffold, to enhance function within the field of tissue engineering. Previous in vitro and murine in vivo analysis identified a polymer blend of poly(l-lactic acid)-poly(ε-caprolactone) (PLLA:PCL 20:80) to have characteristics desirable for bone regeneration. Polymer scaffolds in combination with marrow-derived skeletal stem cells (SSCs) were implanted into mid-shaft ovine 3.5 cm tibial defects, and indices of bone regeneration were compared to groups implanted with scaffolds alone and with empty defects after 12 weeks, including micro-CT, mechanical testing and histological analysis. The critical nature of the defect was confirmed via all modalities. Both the scaffold and scaffold/SSC groups showed enhanced quantitative bone regeneration; however, this was only found to be significant in the scaffold/SSCs group (p = 0.04) and complete defect bridging was not achieved in any group. The mechanical strength was significantly less than that of contralateral control tibiae (p < 0.01) and would not be appropriate for full functional loading in a clinical setting. This study explored the hypothesis that cell therapy would enhance bone formation in a critical-sized defect compared to scaffold alone, using an external fixation construct, to bridge the scale-up gap between small animal studies and potential clinical translation. The model has proved a successful critical defect and analytical techniques have been found to be both valid and reproducible. Further work is required with both scaffold production techniques and cellular protocols in order to successfully scale-up this stem cell/binary blend polymer scaffold. © 2015 The Authors. Journal of Tissue Engineering and Regenerative Medicine published by John Wiley & Sons, Ltd. © 2015 The Authors. Journal of Tissue Engineering and Regenerative Medicine published by John Wiley & Sons, Ltd.

Versatile antifouling polyethersulfone filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive.

PubMed

Zhao, Yi-Fan; Zhang, Pei-Bin; Sun, Jian; Liu, Cui-Jing; Yi, Zhuan; Zhu, Li-Ping; Xu, You-Yi

2015-06-15

Here we describe the development of versatile antifouling polyethersulfone (PES) filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive. Amphiphilic polyethersulfone-block-poly(2-hydroxyethyl methacrylate) (PES-b-PHEMA) was beforehand designed and used as the blending additive of PES membranes prepared by phase inversion technique. The surface enriched PHEMA blocks on membrane surface acted as an anchor to immobilize the initiating site. Poly(sulfobetaine methacrylate) (PSBMA) were subsequently grafted onto the PES blend membranes by surface-initiated atom transfer radical polymerization (SI-ATRP). The analysis of surface chemistry confirmed the successful grafting of zwitterionic PSBMA brushes on PES membrane surface. The resulted PES-g-PSBMA membranes were capable of separating proteins from protein solution and oil from oil/water emulsion efficiently. Furthermore, the modified membranes showed high hydrophilicity and strongly antifouling properties due to the incorporation of well-defined PSBMA layer. In addition, the PES-g-PSBMA membranes exhibited excellent blood compatibility and durability during the washing process. The developed antifouling PES membranes are versatile and can find their applications in protein filtration, blood purification and oil/water separation, etc. Copyright © 2015 Elsevier Inc. All rights reserved.

Passive approach for the improved dispersion of polyvinyl alcohol-based functionalized multi-walled carbon nanotubes/Nafion membranes for polymer electrolyte membrane fuel cells.

PubMed

Abu Sayeed, M D; Talukdar, Krishan; Kim, Hee Jin; Park, Younjin; Gopalan, A I; Kim, Young Ho; Lee, Kwang-Pill; Choi, Sang-June

2014-12-01

Multi-walled carbon nanotubes (MWCNTs) are regarded as ideal fillers for Nafion polymer electrolyte membranes (PEMs) for fuel cell applications. The highly aggregated properties of MWCNTs can be overcome by the successful cross-linking with polyvinyl alcohol (PVA) into the MWCNTs/Nafion membrane. In this study, a series of nanocomposite membranes were fabricated with the PVA-influenced functionalized MWCNTs reinforced into the Nafion polymer matrix by a solution casting method. Several different PVA contents were blended to f-MWCNTs/Nafion nanocomposite membranes followed by successful cross-linking by annealing. The surface morphologies and the inner structures of the resulting PVA-MWCNTs/Nafion nanocomposite membranes were then observed by optical microscopy and scanning electron microscopy (SEM) to investigate the dispersion of MWCNTs into the PVA/Nafion composite membranes. After that, the nanocomposite membranes were characterized by thermo-gravimetric analysis (TGA) to observe the thermal enhancement caused by effective cross-linking between the f-MWCNTs with the composite polymer matrixes. Improved water uptake with reduced methanol uptake revealed the successful fabrication of PVA-blended f-MWCNTs/Nafion membranes. In addition, the ion exchange capacity (IEC) was evaluated for PEM fuel cell (PEMFC) applications.

Enhanced biocompatibility and antibacterial property of polyurethane materials modified with citric acid and chitosan.

PubMed

Liu, Tian-Ming; Wu, Xing-Ze; Qiu, Yun-Ren

2016-08-01

Citric acid (CA) and chitosan (CS) were covalently immobilized on polyurethane (PU) materials to improve the biocompatibility and antibacterial property. The polyurethane pre-polymer with isocyanate group was synthesized by one pot method, and then grafted with citric acid, followed by blending with polyethersulfone (PES) to prepare the blend membrane by phase-inversion method so that chitosan can be grafted from the membrane via esterification and acylation reactions eventually. The native and modified membranes were characterized by attenuated total reflectance-Fourier transform infrared spectroscope, X-ray photoelectron spectroscopy, scanning electron microscopy, water contact angle measurement, and tensile strength test. Protein adsorption, platelet adhesion, hemolysis assay, activated partial thromboplastin time, prothrombin time, thrombin time, and adsorption of Ca(2+) were executed to evaluate the blood compatibility of the membranes decorated by CA and CS. Particularly, the antibacterial activities on the modified membranes were evaluated based on a vitro antibacterial test. It could be concluded that the modified membrane had good anticoagulant property and antibacterial property.

High temperature proton exchange membranes with enhanced proton conductivities at low humidity and high temperature based on polymer blends and block copolymers of poly(1,3-cyclohexadiene) and poly(ethylene glycol)

DOE PAGES

Deng, Shawn; Hassan, Mohammad K.; Nalawade, Amol; ...

2015-09-16

Hot (at 120 °C) and dry (20% relative humidity) operating conditions benefit fuel cell designs based on proton exchange membranes (PEMs) and hydrogen due to simplified system design and increasing tolerance to fuel impurities. In this paper, presented are preparation, partial characterization, and multi-scale modeling of such PEMs based on cross-linked, sulfonated poly(1,3-cyclohexadiene) (xsPCHD) blends and block copolymers with poly(ethylene glycol) (PEG). These low cost materials have proton conductivities 18 times that of current industry standard Nafion at hot, dry operating conditions. Among the membranes studied, the blend xsPCHD-PEG PEM displayed the highest proton conductivity, which exhibits a morphology withmore » higher connectivity of the hydrophilic domain throughout the membrane. Simulation and modeling provide a molecular level understanding of distribution of PEG within this hydrophilic domain and its relation to proton conductivities. Finally, this study demonstrates enhancement of proton conductivity at high temperature and low relative humidity by incorporation of PEG and optimized sulfonation conditions.« less

Preparation, characterization, physical testing and performance of fluorocarbon membranes and separators

NASA Technical Reports Server (NTRS)

Lagow, R. J.; Dumitru, E. T.

1982-01-01

The direct fluorination method of converting carefully selected hydrocarbon substrates to fluorinated membranes was successfully applied to produce promising, novel membranes for electrochemical devices. A family of polymer blends was identified which permits wide latitude in the concentration of both crosslinks and carboxyl groups in hydrocarbon membranes. These membranes were successfully fluorinated and are potentially competitive with commercial membranes in performance, and potentially much cheaper in price.

Phase Behavior of Binary Blends of High Molecular Weight Diblock Copolymers with a Low Molecular Weight Triblock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mickiewicz, Rafal A.; Ntoukas, Eleftherios; Avgeropoulos, Apostolos

2009-08-26

Binary blends of four different high molecular weight poly(styrene-b-isoprene) (SI) diblock copolymers with a lower molecular weight poly(styrene-b-isoprene-b-styrene) (SIS) triblock copolymer were prepared, and their morphology was characterized by transmission electron microscopy and ultra-small-angle X-ray scattering. All the neat block copolymers have nearly symmetric composition and exhibit the lamellar morphology. The SI diblock copolymers had number-average molecular weights, Mn, in the range 4.4 x 10{sup 5}--1.3 x 10{sup 6} g/mol and volume fractions of poly(styrene), {Phi}{sub PS}, in the range 0.43--0.49, and the SIS triblock had a molecular weight of Mn 6.2 x 10{sup 4} g/mol with {Phi}{sub PS} =more » 0.41. The high molecular weight diblock copolymers are very strongly segregating, with interaction parameter values, {chi}N, in the range 470--1410. A morphological phase diagram in the parameter space of molecular weight ratio (R = M{sub n}{sup diblock}/1/2M{sub n}{sup triblock}) and blend composition was constructed, with R values in the range between 14 and 43, which are higher than previously reported. The phase diagram revealed a large miscibility gap for the blends, with macrophase separation into two distinct types of microphase-separated domains for weight fractions of SI, w{sub SI} < 0.9, implying virtually no solubility of the much higher molecular weight diblocks in the lower molecular weight triblock. For certain blend compositions, above R 30, morphological transitions from the lamellar to cylindrical and bicontinuous structures were also observed.« less

Strategies for cell manipulation and skeletal tissue engineering using high-throughput polymer blend formulation and microarray techniques.

PubMed

Khan, Ferdous; Tare, Rahul S; Kanczler, Janos M; Oreffo, Richard O C; Bradley, Mark

2010-03-01

A combination of high-throughput material formulation and microarray techniques were synergistically applied for the efficient analysis of the biological functionality of 135 binary polymer blends. This allowed the identification of cell-compatible biopolymers permissive for human skeletal stem cell growth in both in vitro and in vivo applications. The blended polymeric materials were developed from commercially available, inexpensive and well characterised biodegradable polymers, which on their own lacked both the structural requirements of a scaffold material and, critically, the ability to facilitate cell growth. Blends identified here proved excellent templates for cell attachment, and in addition, a number of blends displayed remarkable bone-like architecture and facilitated bone regeneration by providing 3D biomimetic scaffolds for skeletal cell growth and osteogenic differentiation. This study demonstrates a unique strategy to generate and identify innovative materials with widespread application in cell biology as well as offering a new reparative platform strategy applicable to skeletal tissues. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Improved PVDF membrane performance by doping extracellular polymeric substances of activated sludge.

PubMed

Guan, Yan-Fang; Huang, Bao-Cheng; Qian, Chen; Wang, Long-Fei; Yu, Han-Qing

2017-04-15

Polyvinylidene fluoride (PVDF) membrane has been widely applied in water and wastewater treatment because of its high mechanical strength, thermal stability and chemical resistance. However, the hydrophobic nature of PVDF membrane makes it readily fouled, substantially reducing water flux and overall membrane rejection ability. In this work, an in-situ blending modifier, i.e., extracellular polymeric substances (EPS) from activated sludge, was used to enhance the anti-fouling ability of PVDF membrane. Results indicate that the pure water flux of the membrane and its anti-fouling performance were substantially improved by blending 8% EPS into the membrane. By introducing EPS, the membrane hydrophilicity was increased and the cross section morphology was changed when it interacted with polyvinl pyrrolidone, resulting in the formation of large cavities below the finger-like pores. In addition, the fraction of pores with a size of 100-500 nm increased, which was also beneficial to improving membrane performance. Surface thermodynamic calculations indicate the EPS-functionalized membrane had a higher cohesion free energy, implying its good pollutant rejection and anti-fouling ability. This work provides a simple, efficient and cost-effective method to improve membrane performance and also extends the applications of EPS. Copyright © 2017 Elsevier Ltd. All rights reserved.

A search for Lyman-alpha emission in beta Lyrae from Copernicus

NASA Technical Reports Server (NTRS)

Kondo, Y.; Mccluskey, G. E., Jr.

1974-01-01

High-resolution (0.2 A) spectrophotometric observations of the complex eclipsing binary beta Lyrae were obtained with the Princeton Telescope Spectrometer on the Copernicus satellite. We discuss the search for L-alpha emission in beta Lyrae and compare the Copernicus results with the OAO-2 observations of the same binary system. The possible L-alpha emission features observed from OAO-2 are identified as blends of the emission lines of other elements in the vicinity of L-alpha.

Block copolymers for alkaline fuel cell membrane materials

NASA Astrophysics Data System (ADS)

Li, Yifan

Alkaline fuel cells (AFCs) using anion exchange membranes (AEMs) as electrolyte have recently received considerable attention. AFCs offer some advantages over proton exchange membrane fuel cells, including the potential of non-noble metal (e.g. nickel, silver) catalyst on the cathode, which can dramatically lower the fuel cell cost. The main drawback of traditional AFCs is the use of liquid electrolyte (e.g. aqueous potassium hydroxide), which can result in the formation of carbonate precipitates by reaction with carbon dioxide. AEMs with tethered cations can overcome the precipitates formed in traditional AFCs. Our current research focuses on developing different polymer systems (blend, block, grafted, and crosslinked polymers) in order to understand alkaline fuel cell membrane in many aspects and design optimized anion exchange membranes with better alkaline stability, mechanical integrity and ionic conductivity. A number of distinct materials have been produced and characterized. A polymer blend system comprised of poly(vinylbenzyl chloride)-b-polystyrene (PVBC-b-PS) diblock copolymer, prepared by nitroxide mediated polymerization (NMP), with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) or brominated PPO was studied for conversion into a blend membrane for AEM. The formation of a miscible blend matrix improved mechanical properties while maintaining high ionic conductivity through formation of phase separated ionic domains. Using anionic polymerization, a polyethylene based block copolymer was designed where the polyethylene-based block copolymer formed bicontinuous morphological structures to enhance the hydroxide conductivity (up to 94 mS/cm at 80 °C) while excellent mechanical properties (strain up to 205%) of the polyethylene block copolymer membrane was observed. A polymer system was designed and characterized with monomethoxy polyethylene glycol (mPEG) as a hydrophilic polymer grafted through substitution of pendent benzyl chloride groups of a PVBC-b-PS. The incorporation of the hydrophilic polymer allows for an investigation of the effect of hydration on ionic conductivity, resulting in the increase in membrane water affinity, enhancement of conductivity and reduced dependence of conductivity on relative humidity. A study of crosslinking of block copolymers was done wherein the crosslinking occurs in the non-matrix phase in order to maintain mechanical properties. The formation of a cationic crosslinked structure improves the mechanical integrity of the membrane in water while showing little deleterious effect on ionic conductivity and mechanical properties.

Predicting the composition of red wine blends using an array of multicomponent Peptide-based sensors.

PubMed

Ghanem, Eman; Hopfer, Helene; Navarro, Andrea; Ritzer, Maxwell S; Mahmood, Lina; Fredell, Morgan; Cubley, Ashley; Bolen, Jessica; Fattah, Rabia; Teasdale, Katherine; Lieu, Linh; Chua, Tedmund; Marini, Federico; Heymann, Hildegarde; Anslyn, Eric V

2015-05-20

Differential sensing using synthetic receptors as mimics of the mammalian senses of taste and smell is a powerful approach for the analysis of complex mixtures. Herein, we report on the effectiveness of a cross-reactive, supramolecular, peptide-based sensing array in differentiating and predicting the composition of red wine blends. Fifteen blends of Cabernet Sauvignon, Merlot and Cabernet Franc, in addition to the mono varietals, were used in this investigation. Linear Discriminant Analysis (LDA) showed a clear differentiation of blends based on tannin concentration and composition where certain mono varietals like Cabernet Sauvignon seemed to contribute less to the overall characteristics of the blend. Partial Least Squares (PLS) Regression and cross validation were used to build a predictive model for the responses of the receptors to eleven binary blends and the three mono varietals. The optimized model was later used to predict the percentage of each mono varietal in an independent test set composted of four tri-blends with a 15% average error. A partial least square regression model using the mouth-feel and taste descriptive sensory attributes of the wine blends revealed a strong correlation of the receptors to perceived astringency, which is indicative of selective binding to polyphenols in wine.

Supertoughened renewable PLA reactive multiphase blends system: phase morphology and performance.

PubMed

Zhang, Kunyu; Nagarajan, Vidhya; Misra, Manjusri; Mohanty, Amar K

2014-08-13

Multiphase blends of poly(lactic acid) (PLA), ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA) terpolymer, and a series of renewable poly(ether-b-amide) elastomeric copolymer (PEBA) were fabricated through reactive melt blending in an effort to improve the toughness of the PLA. Supertoughened PLA blend showing impact strength of ∼500 J/m with partial break impact behavior was achieved at an optimized blending ratio of 70 wt % PLA, 20 wt % EMA-GMA, and 10 wt % PEBA. Miscibility and thermal behavior of the binary blends PLA/PEBA and PLA/EMA-GMA, and the multiphase blends were also investigated through differential scanning calorimetric (DSC) and dynamic mechanical analysis (DMA). Phase morphology and fracture surface morphology of the blends were studied through scanning electron microscopy (SEM) and atomic force microscopy (AFM) to understand the strong corelation between the morphology and its significant effect on imparting tremendous improvement in toughness. A unique "multiple stacked structure" with partial encapsulation of EMA-GMA and PEBA minor phases was observed for the PLA/EMA-GMA/PEBA (70/20/10) revealing the importance of particular blend composition in enhancing the toughness. Toughening mechanism behind the supertoughened PLA blends have been established by studying the impact fractured surface morphology at different zones of fracture. Synergistic effect of good interfacial adhesion and interfacial cavitations followed by massive shear yielding of the matrix was believed to contribute to the enormous toughening effect observed in these multiphase blends.

Demixing of polymers under nanoimprinting process

NASA Astrophysics Data System (ADS)

Wang, Zhen

Polymer blend has been an important area in polymer science for decades. The knowledge of polymer blend in bulk is well established and technologies based on it have created products ubiquitous in our daily life. More intriguing problem arises when the phase separation of a polymer blend occurs under physical confinement. In this thesis, we investigated the effect of interfacial interactions between constituent polymers and confinement environment on phase evolution. Specifically, morphologies of thin films of binary polymer blends were examined on chemically homogenous substrates (preferential surface, neutral surface), on chemical pattern, between two parallel rigid substrates, and under thermal embossing/step-and-flash nanoimprint lithography conditions. We found that preferential wetting of selective component dominates the phase evolution, which can be suppressed by the use of neutral surfaces or external pressure. By manipulating these factors, a wide range of unique non-equilibrium micro or nanostructures can thus be achieved.

Predicting Flory-Huggins χ from Simulations

NASA Astrophysics Data System (ADS)

Zhang, Wenlin; Gomez, Enrique D.; Milner, Scott T.

2017-07-01

We introduce a method, based on a novel thermodynamic integration scheme, to extract the Flory-Huggins χ parameter as small as 10-3k T for polymer blends from molecular dynamics (MD) simulations. We obtain χ for the archetypical coarse-grained model of nonpolar polymer blends: flexible bead-spring chains with different Lennard-Jones interactions between A and B monomers. Using these χ values and a lattice version of self-consistent field theory (SCFT), we predict the shape of planar interfaces for phase-separated binary blends. Our SCFT results agree with MD simulations, validating both the predicted χ values and our thermodynamic integration method. Combined with atomistic simulations, our method can be applied to predict χ for new polymers from their chemical structures.

Separator for lithium-sulfur battery based on polymer blend membrane

NASA Astrophysics Data System (ADS)

Freitag, Anne; Stamm, Manfred; Ionov, Leonid

2017-09-01

In this work we report a novel way of reducing the polysulfide shuttle in lithium-sulfur batteries by a new separator material. Polyvinylsulfate potassium salt (PVSK) as polymeric additive is introduced into a polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) matrix membrane to improve the battery performance. PVSK is expected to lower the polysulfide mobility due to interaction with the sulfonic group. PVdF-HFP/PVSK blend membranes are prepared and an UV/Vis polysulfide diffusion test clearly demonstrates the positive effect of PVSK. Electrochemical testing reveals a significant improvement of cycling stability up to more than 200 cycles. In addition, the effect of separator porosity to the polysulfide shuttle is investigated with PVdF-HFP membranes of different porosity. A simple polysulfide diffusion test and potentiostatic charge/discharge cycling clearly demonstrate that low separator porosity is favorable in a lithium-sulfur cell.

Poly(vinylbenzylchloride) Based Anion-Exchange Blend Membranes (AEBMs): Influence of PEG Additive on Conductivity and Stability

PubMed Central

Kerres, Jochen A.; Krieg, Henning M.

2017-01-01

In view of the many possible applications such as fuel cells and electrolysers, recent interest in novel anion exchange membranes (AEMs) has increased significantly. However, their low conductivity and chemical stability limits their current suitability. In this study, the synthesis and characterization of several three- and four-component anion exchange blend membranes (AEBMs) is described, where the compositions have been systematically varied to study the influence of the AEBM’s composition on the anion conductivities as well as chemical and thermal stabilities under strongly alkaline conditions. It was shown that the epoxide-functionalized poly(ethylene glycol)s that were introduced into the four-component AEBMs resulted in increased conductivity as well as a marked improvement in the stability of the AEBMs in an alkaline environment. In addition, the thermal stability of the novel AEBMs was excellent showing the suitability of these membranes for several electrochemical applications. PMID:28621717

Effect of temperature gradient on liquid-liquid phase separation in a polyolefin blend.

PubMed

Jiang, Hua; Dou, Nannan; Fan, Guoqiang; Yang, Zhaohui; Zhang, Xiaohua

2013-09-28

We have investigated experimentally the structure formation processes during phase separation via spinodal decomposition above and below the spinodal line in a binary polymer blend system exposed to in-plane stationary thermal gradients using phase contrast optical microscopy and temperature gradient hot stage. Below the spinodal line there is a coupling of concentration fluctuations and thermal gradient imposed by the temperature gradient hot stage. Also under the thermal gradient annealing phase-separated domains grow faster compared with the system under homogeneous temperature annealing on a zero-gradient or a conventional hot stage. We suggest that the in-plane thermal gradient accelerates phase separation through the enhancement in concentration fluctuations in the early and intermediate stages of spinodal decomposition. In a thermal gradient field, the strength of concentration fluctuation close to the critical point (above the spinodal line) is strong enough to induce phase separation even in one-phase regime of the phase diagram. In the presence of a temperature gradient the equilibrium phase diagrams are no longer valid, and the systems with an upper critical solution temperature can be quenched into phase separation by applying the stationary temperature gradient. The in-plane temperature gradient drives enhanced concentration fluctuations in a binary polymer blend system above and below the spinodal line.

Unmasking the hidden NGTS-3Ab: a hot Jupiter in an unresolved binary system

NASA Astrophysics Data System (ADS)

Günther, Maximilian N.; Queloz, Didier; Gillen, Edward; Delrez, Laetitia; Bouchy, François; McCormac, James; Smalley, Barry; Almleaky, Yaseen; Armstrong, David J.; Bayliss, Daniel; Burdanov, Artem; Burleigh, Matthew; Cabrera, Juan; Casewell, Sarah L.; Cooke, Benjamin F.; Csizmadia, Szilárd; Ducrot, Elsa; Eigmüller, Philipp; Erikson, Anders; Gänsicke, Boris T.; Gibson, Neale P.; Gillon, Michaël; Goad, Michael R.; Jehin, Emmanuël; Jenkins, James S.; Louden, Tom; Moyano, Maximiliano; Murray, Catriona; Pollacco, Don; Poppenhaeger, Katja; Rauer, Heike; Raynard, Liam; Smith, Alexis M. S.; Sohy, Sandrine; Thompson, Samantha J.; Udry, Stéphane; Watson, Christopher A.; West, Richard G.; Wheatley, Peter J.

2018-05-01

We present the discovery of NGTS-3Ab, a hot Jupiter found transiting the primary star of an unresolved binary system. We develop a joint analysis of multi-colour photometry, centroids, radial velocity (RV) cross-correlation function (CCF) profiles and their bisector inverse slopes (BIS) to disentangle this three-body system. Data from the Next Generation Transit Survey (NGTS), SPECULOOS and HARPS are analysed and modelled with our new BLENDFITTER software. We find that the binary consists of NGTS-3A (G6V-dwarf) and NGTS-3B (K1V-dwarf) at <1" separation. NGTS-3Ab orbits every 1.675 days. The planet radius and mass are Rplanet=1.48 ± 0.37 RJand Mplanet=2.38 ± 0.26 MJ, suggesting it is potentially inflated. We emphasise that only combining all the information from multi-colour photometry, centroids and RV CCF profiles can resolve systems like NGTS-3. Such systems cannot be disentangled from single-colour photometry and RV measurements alone. Importantly, the presence of a BIS correlation indicates a blend scenario, but is not sufficient to determine which star is orbited by the third body. Moreover, even if no BIS correlation is detected, a blend scenario cannot be ruled out without further information. The choice of methodology for calculating the BIS can influence the measured significance of its correlation. The presented findings are crucial to consider for wide-field transit surveys, which require wide CCD pixels (>5") and are prone to contamination by blended objects. With TESS on the horizon, it is pivotal for the candidate vetting to incorporate all available follow-up information from multi-colour photometry and RV CCF profiles.

Integrating seawater desalination and wastewater reclamation forward osmosis process using thin-film composite mixed matrix membrane with functionalized carbon nanotube blended polyethersulfone support layer.

PubMed

Choi, Hyeon-Gyu; Son, Moon; Choi, Heechul

2017-10-01

Thin-film composite mixed matrix membrane (TFC MMM) with functionalized carbon nanotube (fCNT) blended in polyethersulfone (PES) support layer was synthesized via interfacial polymerization and phase inversion. This membrane was firstly tested in lab-scale integrating seawater desalination and wastewater reclamation forward osmosis (FO) process. Water flux of TFC MMM was increased by 72% compared to that of TFC membrane due to enhanced hydrophilicity. Although TFC MMM showed lower water flux than TFC commercial membrane, enhanced reverse salt flux selectivity (RSFS) of TFC MMM was observed compared to TFC membrane (15% higher) and TFC commercial membrane (4% higher), representing membrane permselectivity. Under effluent organic matter (EfOM) fouling test, 16% less normalized flux decline of TFC MMM was observed compared to TFC membrane. There was 8% less decline of TFC MMM compared to TFC commercial membrane due to fCNT effect on repulsive foulant-membrane interaction enhancement, caused by negatively charged membrane surface. After 10 min physical cleaning, TFC MMM displayed higher recovered normalized flux than TFC membrane (6%) and TFC commercial membrane (4%); this was also supported by visualized characterization of fouling layer. This study presents application of TFC MMM to integrated seawater desalination and wastewater reclamation FO process for the first time. It can be concluded that EfOM fouling of TFC MMM was suppressed due to repulsive foulant-membrane interaction. Copyright © 2017 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryabova, N. Yu., E-mail: rny03@nf.jinr.ru; Kiselev, M. A.; Balagurov, A. M.

The structural changes in the multilamellar lipid membranes of dipalmitoylphosphatidylcholine (DPPC)/cholesterol and DPPC/ceramide VI binary systems during hydration and dehydration have been studied by neutron diffraction. The effect of cholesterol and ceramide on the kinetics of water exchange in DPPC membranes is characterized. Compared to pure DPPC, membranes of binary systems swell faster during hydration (with a characteristic time of {approx}30 min). Both compounds, ceramide VI and cholesterol, similarly affect the hydration of DPPC membranes, increasing the repeat distance due to the bilayer growth. However, in contrast to cholesterol, ceramide significantly reduces the thickness of the membrane water layer. Themore » introduction of cholesterol into a DPPC membrane slows down the change in the parameters of the bilayer internal structure during dehydration. In the DPPC/ceramide VI/cholesterol ternary system (with a molar cholesterol concentration of 40%), cholesterol is partially released from the lamellar membrane structure into the crystalline phase.« less

Use of pilot plant scale continuous fryer to simulate industrial production of potato chips: thermal properties of palm olein blends under continuous frying conditions

PubMed Central

Tarmizi, Azmil Haizam Ahmad; Ismail, Razali

2014-01-01

Binary blends of palm olein (PO) with sunflower oil (SFO), canola oil (CNO), and cottonseed oil (CSO) were formulated to assess their stability under continuous frying conditions. The results were then compared with those obtained in PO. The oil blends studied were: (1) 60:40 for PO + SFO; (2) 70:30 for PO + CNO; and (3) 50:50 for PO + CSO. The PO and its blends were used to fry potato chips at 180°C for a total of 56 h of operation. The evolution of analytical parameters such as tocols, induction period, color, p-anisidine value, free fatty acid, smoke point, polar compounds, and polymer compounds were evaluated over the frying time. Blending PO with unsaturated oils was generally proved to keep most qualitative parameters comparable to those demonstrated in PO. Indeed, none of the oils surpassed the legislative limits for used frying. Overall, it was noted that oil containing PO and SFO showed higher resistance toward oxidative and hydrolytic behaviors as compared to the other oil blends. PMID:24804062

Effect of high pressure microfluidization on the crystallization behavior of palm stearin - palm olein blends.

PubMed

Han, Lijuan; Li, Lin; Li, Bing; Zhao, Lei; Liu, Guoqin; Liu, Xinqi; Wang, Xuede

2014-04-24

Moderate and high microfluidization pressures (60 and 120 MPa) and different treatment times (once and twice) were used to investigate the effect of high-pressure microfluidization (HPM) treatment on the crystallization behavior and physical properties of binary mixtures of palm stearin (PS) and palm olein (PO). The polarized light microscopy (PLM), texture analyzer, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) techniques were applied to analyze the changes in crystal network structure, hardness, polymorphism and thermal property of the control and treated blends. PLM results showed that HPM caused significant reductions in maximum crystal diameter in all treated blends, and thus led to changes in the crystal network structure, and finally caused higher hardness in than the control blends. The XRD study demonstrated that HPM altered crystalline polymorphism. The HPM-treated blends showed a predominance of the more stable β' form, which is of more interest for food applications, while the control blend had more α- and β-form. This result was further confirmed by DSC observations. These changes in crystallization behavior indicated that HPM treatment was more likely to modify the crystallization processes and nucleation mechanisms.

Asymmetric block copolymer membranes with ultrahigh porosity and hierarchical pore structure by plain solvent evaporation.

PubMed

Yu, H; Qiu, X; Behzad, A R; Musteata, V; Smilgies, D-M; Nunes, S P; Peinemann, K-V

2016-10-04

Membranes with a hierarchical porous structure could be manufactured from a block copolymer blend by pure solvent evaporation. Uniform pores in a 30 nm thin skin layer supported by a macroporous structure were formed. This new process is attractive for membrane production because of its simplicity and the lack of liquid waste.

In-line monitoring of a pharmaceutical blending process using FT-Raman spectroscopy.

PubMed

Vergote, G J; De Beer, T R M; Vervaet, C; Remon, J P; Baeyens, W R G; Diericx, N; Verpoort, F

2004-03-01

FT-Raman spectroscopy (in combination with a fibre optic probe) was evaluated as an in-line tool to monitor a blending process of diltiazem hydrochloride pellets and paraffinic wax beads. The mean square of differences (MSD) between two consecutive spectra was used to identify the time required to obtain a homogeneous mixture. A traditional end-sampling thief probe was used to collect samples, followed by HPLC analysis to verify the Raman data. Large variations were seen in the FT-Raman spectra logged during the initial minutes of the blending process using a binary mixture (ratio: 50/50, w/w) of diltiazem pellets and paraffinic wax beads (particle size: 800-1200 microm). The MSD-profiles showed that a homogeneous mixture was obtained after about 15 min blending. HPLC analysis confirmed these observations. The Raman data showed that the mixing kinetics depended on the particle size of the material and on the mixing speed. The results of this study proved that FT-Raman spectroscopy can be successfully implemented as an in-line monitoring tool for blending processes.

Compatibilizing Bulk Polymer Blends by Using Organoclays

NASA Astrophysics Data System (ADS)

Si, Mayu; Gersappe, Dilip; Zhang, Wenhua; Ade, Harald; Rafailovich, Miriam; Sokolov, Jonathan; Rudomen, Gregory; Schwartz, Bradley; Fisher, Robert

2004-03-01

We investigated the compatiblizing performance of organoclays on melt mixed binary and tertiary polymer blends, such as, PS/PMMA, PC/SAN, PS/PMMA/PVC and PS/PMMA/PE. These polymer blends were characterized by TEM, STXM, DSC and DMA. TEM and STXM photographs show that the addition of organoclays into polymer blends drastically reduces the average domain size of the component phases. And the organoclay goes to the interfacial region between the different polymers and effectively slows down the domain size increasing during high temperature annealing. DMA and DSC results show the effect of organoclays on the mechanical properties and glass transitions temperature, which indicates the compatibilization on the molecular level. The generalized compatibilization induced by the nanoscale fillers for blends can be explained in terms of mean field models where the reduction of interfacial tension induced by in-situ grafting is counterbalanced by the increased bending energy due to the rigidity of the filler. This in turn can be shown to be a function of the degree of exfoliation, aspect ratio, and polymer filler interactions. Supported by NSF funded MRSEC at Stony Brook

Thermal casting process for the preparation of anisotropic membranes and the resultant membrane

DOEpatents

Caneba, Gerard T. M.; Soong, David S.

1987-01-01

A method for providing anisotropic polymer membranes from a binary polymer/solvent solution using a thermal inversion process. A homogeneous binary solution is cast onto a support and cooled in such a way as to provide a differential in cooling rate across the thickness of the resulting membrane sheet. Isotropic or anisotropic structures of selected porosities can be produced, depending on the initial concentration of polymer in the selected solvent and on the extent of the differential in cooling rate. This differential results in a corresponding gradation in pore size. The method may be modified to provide a working skin by applying a rapid, high-temperature pulse to redissolve a predetermined thickness of the membrane at one of its faces and then freezing the entire structure.

Study of flame combustion of off-design binary coal blends in steam boilers

NASA Astrophysics Data System (ADS)

Kapustyanskii, A. A.

2017-07-01

Changes in the structure of the fuel consumption by the thermal power stations of Ukraine caused by failure in supplying anthracite from the Donets Basin are analyzed and the major tasks of maintaining the functioning of the coal industry are formulated. The possibility of using, in the near future, the flame combustion of off-design solid fuels in the power boilers of the thermal power plants and combined heat and power plants is studied. The article presents results of expert tests of the TPP-210A and TP-15 boilers under flame combustion of mixtures of anthracites, lean coal, and the coal from the RSA in various combinations. When combusting, such mixtures have higher values of the combustibles yield and the ash fusibility temperature. The existence of the synergetic effect in the flame combustion of binary coal blends with different degrees of metamorphism is discussed. A number of top-priority measures have been worked out that allow for switching over the boilers designed to be fired with anthracite to using blends of coals of different ranks. Zoned thermal analysis of the TP-15 boiler furnace was performed for numerical investigation of the temperature distribution between the furnace chamber zones and exploration of the possibility of the liquid slag disposal and the temperature conditions for realization of this process. A positive result was achieved by combusting anthracite culm (AC), the coal from the RSA, and their mixtures with lean coal within the entire range of the working loads of the boilers in question. The problems of normalization of the liquid slag flow were also successfully solved without closing the slag notch. The results obtained by balance experiments suggest that the characteristics of the flame combustion of a binary blend, i.e., the temperature conditions in the furnace, the support flame values, and the degree of the fuel burnout, are similar to the characteristics of the flame of the coal with a higher reactive capacity, which proves the existence of the synergetic effect in the processes of cocombustion of coals of various grades.

Poly(2,6-dimethyl-1,4-phenylene oxide) Blended with Poly (vinylbenzyl chloride)-b-polystyrene for the Formation of Anion Exchange Membranes

DTIC Science & Technology

2014-08-14

show improved mechanical properties compared to the styrenic copolymer, particularly in a hydrated condition. The membranes were subjected to...AEMs) show improved mechanical properties compared to the styrenic copolymer, particularly in a hydrated condition. The membranes were subjected to...deionized water, and after 24 h of soaking, the fully hydrated membranes were removed from the water; any residual bulk water on the membrane surface was

Reverse indentation size effects in gamma irradiated blood compatible blend films of chitosan-poly (vinyl alcohol) for possible medical applications.

PubMed

Bisen, D S; Bhatt, Rinkesh; Bajpai, A K; Bajpai, R; Katare, R

2017-02-01

In the present work binary blends of polyvinyl alcohol (PVA) and chitosan (CS) were prepared by solution cast method and characterized by analytical methods like FTIR, XRD and SEM for seeking structural and morphological information. The blends were exposed to gamma radiation and evaluated for their improved mechanical strength. It was found that the tensile strength and microhardness increased after irradiation of CS-PVA films. Plastic effect due to absorption of water molecules and scissoring effect due to gamma irradiation were found to decrease the softness or increase the microhardness of the blends. Improved mechanical properties were attributed to intermolecular and intramolecular hydrogen bonds and adhesive nature of the blends also. The blends were also investigated for water intake behavior and in vitro blood compatibility property on the basis of certain in vitro tests like protein adsorption, haemolysis and blood clot formation on the un-irradiated and irradiated blend samples. The increased % swelling with time could be assigned to the fact that increasing water content facilitates the phase separation process within the blend which results in advancement in interstitial nano-void spaces which are occupied by water molecules. The blood compatibility results showed that when the amount of CS was varied from 0.5% to 2%, the amount of blood clot and percent haemolysis decreased while the protein adsorption increased with increasing CS content of the blend films. Copyright © 2016 Elsevier B.V. All rights reserved.

Radiation-grafted proton exchange membranes based on co-grafting from binary monomer mixtures into poly(ethylene-co-tetrafluoroethylene) (ETFE) film

NASA Astrophysics Data System (ADS)

Sohn, Joon-Yong; Sung, Hae-Jun; Song, Joo-Myung; Shin, Junhwa; Nho, Young-Chang

2012-08-01

In this study, proton exchange membranes (PEMs) based on a poly(ethylene-co-tetrafluoroethylene) (ETFE) film were synthesized through the graft copolymerization of styrene and VTMS (vinyltrimethoxysilane), or styrene and TMSPM (3-(trimethoxysilyl) propyl methacrylate) binary monomer systems using a simultaneous irradiation method. The prepared membranes with the similar degrees of grafting were investigated by measuring ion exchange capacity, proton conductivity, water uptake, chemical stability, and dimensional stability. The results indicate that the silane-crosslinked proton exchange membrane (PEM) has not only lower water uptake and dimensional change but also high proton conductivity at low humidity condition compared to non-crosslinked poly(ethylene-co-tetrafluoroethylene)-g-poly(styrene sulfonic acid) (ETFE-g-PSSA). Also, the chemical stability of silane-crosslinked fuel cell membranes was more improved than that of non-crosslinked fuel cell membrane.

Substrats poreux biodegradables prepares a partir de phases co-continues dans les melanges de polymeres immiscibles

NASA Astrophysics Data System (ADS)

Sarazin, Pierre

2003-06-01

In this thesis a novel approach to preparing biodegradable materials with highly structured and interconnected porosity is proposed. The method involves the controlled preparation of immiscible co-continuous polymer blends using melt-processing technology followed by a bulk solvent extraction step of one of the phases (the porogen phase). A co-continuous structure is defined as the state when each phase of the blend is fully interconnected through a continuous pathway. This method allows for the preparation of porous materials with highly controlled pore size, pore volume and pore shape which can then be transformed and shaped in various forms useful for biomedical applications. Various properties of the skin of the polymeric articles (closed-cell, open-cell, modification of the pore size) can be controlled. Initially, the study on the immiscible binary and compatibilized poly(L-lactide)/polystyrene blends (PLLA/PS) after extraction of the PS phase demonstrated that highly percolated blends exist from 40--75%PS and 40--60%PS for the binary and compatibilized blends, respectively. It is demonstrated that both the pore size and extent of co-continuity can be controlled through composition and interfacial modification. The subsequent part of our work treats of the preparation of porous PLLA from a blend of two biodegradable polymers and the performance of such porous materials. This portion of the work uses only polymer materials which have been medically approved for internal use. In this case, small amounts of the porogen phase can be tolerated in the final porous substrate. Co-continuous blends comprised of poly(L-lactide)/Poly(epsilon-caprolactone) PLLA/PCL, were prepared via melt processing. A wide range of phase sizes for the co-continuous blend is generated through a combination of concentration control and quiescent annealing. As the PLLA phase can not be dissolved selectively in PLLA/PS blends, the co-continuity range was evaluated indirectly. To precisely assess the formation of the co-continuous morphology, the polylactide was replaced by a poly(epsilon-caprolactone) (PCL) in the following work. PCL possesses a similar biocompatibility, although it exhibits a much slower degradation rate. These results practically allow for a separation of the effects of deformation/disintegration processes and coalescence on continuous and co-continuous morphology development. Coalescence phenomena for systems such as the PS in PCL case is clearly the dominant parameter controlling phase size at higher compositions. These results underline the requirement of co-continuity models to include parameters related to coalescence effects. The data indicate the significant potential of mixing temperature as a tool for the morphology control of co-continuous polymer blends. (Abstract shortened by UMI.)

Phase-Resolved Spectroscopy of the Low-Mass X-ray Binary V801 Ara

NASA Astrophysics Data System (ADS)

Brauer, Kaley; Vrtilek, Saeqa Dil; Peris, Charith; McCollough, Michael

2018-06-01

We present phase-resolved optical spectra of the low mass X-ray binary system V801 Ara. The spectra, obtained in 2014 with IMACS on the Magellan/Baade telescope at Las Campanas Observatory, cover the full binary orbit of 3.8 hours. They contain strong emission features allowing us to map the emission of Hα, Hβ, He II λ4686, and the Bowen blend at λ4640. The radial velocity curves of the Bowen blend shows significantly stronger modulation at the orbital period than Hα as expected for the former originating on the secondary with the latter consistent with emission dominated by the disk. Our tomograms of Hα and Hβ are the most detailed studies of these lines for V801 to date and they clearly detect the accretion disk. The Hβ emission extends to higher velocities than Hα, suggesting emission from closer to the neutron star and differentiating temperature variance in the accretion disk for the first time. The center of the accretion disk appears offset from the center-of-mass of the neutron star as has been seen in several other X-ray binaries. This is often interpreted to imply disk eccentricity. Our tomograms do not show strong evidence for a hot spot at the point where the accretion stream hits the disk. This could imply a reduced accretion rate or could be due to the spot being drowned out by bright accretion flow around it. There is enhanced emission further along the disk, however, which implies gas stream interaction downstream of the hot spot.

Evaluation of 165 deg F reverse osmosis modules for washwater purification.

NASA Technical Reports Server (NTRS)

Hossain, S.; Goldsmith, R. L.; Tan, M.; Wydeven, T.; Leban, M. I.

1973-01-01

Three membrane systems have been evaluated for concentration at 165 F of wash-water contaminants. Membranes tested are polybenzimidazole (hollow fibers), cellulose acetate blend (spiral wound), and sulfonated polyphenylene oxide (plate-and-frame). Detailed membrane flux and rejection data are presented for 200-hr life tests with synthetic wash water, at two concentrations, and real wash water, at one concentration. Advantages and limitations of the membrane configurations, are discussed.

Zeolitic Imidazolate Framework-8 Membrane for H2/CO2 Separation: Experimental and Modeling

NASA Astrophysics Data System (ADS)

Lai, L. S.; Yeong, Y. F.; Lau, K. K.; Azmi, M. S.; Chew, T. L.

2018-03-01

In this work, ZIF-8 membrane synthesized through solvent evaporation secondary seeded growth was tested for single gas permeation and binary gases separation of H2 and CO2. Subsequently, a modified mathematical modeling combining the effects of membrane and support layers was applied to represent the gas transport properties of ZIF-8 membrane. Results showed that, the membrane has exhibited H2/CO2 ideal selectivity of 5.83 and separation factor of 3.28 at 100 kPa and 303 K. Besides, the experimental results were fitted well with the simulated results by demonstrating means absolute error (MAE) values ranged from 1.13 % to 3.88 % for single gas permeation and 10.81 % to 21.22 % for binary gases separation. Based on the simulated data, most of the H2 and CO2 gas molecules have transported through the molecular pores of membrane layer, which was up to 70 %. Thus, the gas transport of the gases is mainly dominated by adsorption and diffusion across the membrane.

Enhanced antifouling and antibacterial properties of poly (ether sulfone) membrane modified through blending with sulfonated poly (aryl ether sulfone) and copper nanoparticles

NASA Astrophysics Data System (ADS)

Zhang, Jingjing; Xu, Ya'nan; Chen, Shouwen; Li, Jiansheng; Han, Weiqing; Sun, Xiuyun; Wu, Dihua; Hu, Zhaoxia; Wang, Lianjun

2018-03-01

A series of novel blend ultrafiltration (UF) membranes have been successfully prepared from commercial poly (ether sulfone), lab-synthesized sulfonated poly (aryl ether sulfone) (SPAES, 1 wt%) and copper nanoparticles (0 ∼ 0.4 wt%) via immersion precipitation phase conversion. The micro-structure and separation performance of the membranes were characterized by field emission scanning electron microscopy (SEM) and cross-flow filtration experiments, respectively. Sodium alginate, bovine serum albumin and humic acid were chosen as model organic foulants to investigate the antifouling properties, while E. coil was used to evaluate the antibacterial property of the fabricated membranes. By the incorporation with SPAES and copper nanoparticles, the hydrophilicity, antifouling and antibacterial properties of the modified UF membranes have been profoundly improved. At a copper nanoparticles content of 0.4 wt%, the PES/SPAES/nCu(0.4) membrane exhibited a high pure water flux of 193.0 kg/m2 h, reaching the smallest contact angle of 52°, highest flux recovery ratio of 79% and largest antibacterial rate of 78.9%. Furthermore, the stability of copper nanoparticles inside the membrane matrix was also considerably enhanced, the copper nanoparticles were less than 0.08 mg/L in the effluent during the whole operation.

The extraneous eclipses on binary light curves: KIC 5255552, KIC 10091110, and KIC 11495766

NASA Astrophysics Data System (ADS)

Zhang, J.; Qian, S. B.; Wang, S. M.; Sun, L. L.; Wu, Y.; Jiang, L. Q.

2018-03-01

Aims: We aim to find more eclipsing multiple systems and obtain their parameters, thus increasing our understanding of multiple systems. Methods: The extraneous eclipses on the Kepler binary light curves indicating extraneous bodies were searched. The binary light curves were analyzed using the binary model, and the extraneous eclipses were studied on their periodicity and shape changes. Results: Three binaries with extraneous eclipses on the binary light curves were found and studied based on the Kepler observations. The object KIC 5255552 is an eclipsing triple system with a fast changing inner binary and an outer companion uncovered by three groups of extraneous eclipses of 862.1(±0.1) d period. The KIC 10091110 is suggested to be a double eclipsing binary system with several possible extraordinary coincidences: the two binaries share similar extremely small mass ratios (0.060(13) and 0.0564(18)), similar mean primary densities (0.3264(42) ρ⊙ and 0.3019(28) ρ⊙), and, most notably, the ratio of the two binaries' periods is very close to integer 2 (8.5303353/4.2185174 = 2.022). The KIC 11495766 is a probable triple system with a 120.73 d period binary and (at least) one non-eclipse companion. Furthermore, very close to it in the celestial sphere, there is a blended background stellar binary of 8.3404432 d period. A first list of 25 eclipsing multiple candidates is presented, with the hope that it will be beneficial for study of eclipsing multiples.

Ternary semitransparent organic solar cells with a laminated top electrode

PubMed Central

Makha, Mohammed; Testa, Paolo; Anantharaman, Surendra Babu; Heier, Jakob; Jenatsch, Sandra; Leclaire, Nicolas; Tisserant, Jean-Nicolas; Véron, Anna C.; Wang, Lei; Nüesch, Frank; Hany, Roland

2017-01-01

Abstract Tinted and colour-neutral semitransparent organic photovoltaic elements are of interest for building-integrated applications in windows, on glass roofs or on facades. We demonstrate a semitransparent organic photovoltaic cell with a dry-laminated top electrode that achieves a uniform average visible transmittance of 51% and a power conversion efficiency of 3%. The photo-active material is based on a majority blend composed of a visibly absorbing donor polymer and a fullerene acceptor, to which a selective near-infrared absorbing cyanine dye is added as a minority component. Our results show that organic ternary blends are attractive for the fabrication of semitransparent solar cells in general, because a guest component with a complementary absorption can compensate for the inevitably reduced current generation capability of a high-performing binary blend when applied as a thin, semitransparent film. PMID:28179960

Ternary semitransparent organic solar cells with a laminated top electrode.

PubMed

Makha, Mohammed; Testa, Paolo; Anantharaman, Surendra Babu; Heier, Jakob; Jenatsch, Sandra; Leclaire, Nicolas; Tisserant, Jean-Nicolas; Véron, Anna C; Wang, Lei; Nüesch, Frank; Hany, Roland

2017-01-01

Tinted and colour-neutral semitransparent organic photovoltaic elements are of interest for building-integrated applications in windows, on glass roofs or on facades. We demonstrate a semitransparent organic photovoltaic cell with a dry-laminated top electrode that achieves a uniform average visible transmittance of 51% and a power conversion efficiency of 3%. The photo-active material is based on a majority blend composed of a visibly absorbing donor polymer and a fullerene acceptor, to which a selective near-infrared absorbing cyanine dye is added as a minority component. Our results show that organic ternary blends are attractive for the fabrication of semitransparent solar cells in general, because a guest component with a complementary absorption can compensate for the inevitably reduced current generation capability of a high-performing binary blend when applied as a thin, semitransparent film.

Ternary semitransparent organic solar cells with a laminated top electrode

NASA Astrophysics Data System (ADS)

Makha, Mohammed; Testa, Paolo; Anantharaman, Surendra Babu; Heier, Jakob; Jenatsch, Sandra; Leclaire, Nicolas; Tisserant, Jean-Nicolas; Véron, Anna C.; Wang, Lei; Nüesch, Frank; Hany, Roland

2017-12-01

Tinted and colour-neutral semitransparent organic photovoltaic elements are of interest for building-integrated applications in windows, on glass roofs or on facades. We demonstrate a semitransparent organic photovoltaic cell with a dry-laminated top electrode that achieves a uniform average visible transmittance of 51% and a power conversion efficiency of 3%. The photo-active material is based on a majority blend composed of a visibly absorbing donor polymer and a fullerene acceptor, to which a selective near-infrared absorbing cyanine dye is added as a minority component. Our results show that organic ternary blends are attractive for the fabrication of semitransparent solar cells in general, because a guest component with a complementary absorption can compensate for the inevitably reduced current generation capability of a high-performing binary blend when applied as a thin, semitransparent film.

TRANSPORT PROPERTIES OF CROSSLINKABLE POLYIMIDE BLENDS. (R824727)

EPA Science Inventory

Abstract

The use of polymeric membranes for separation of chemically aggressive media, or at elevated temperatures, has been limited by membrane availability. While a number of polymers are both resistant to chemical dissolution and thermally stable to over 300°C,...

Insight Into the Role of PC71BM on Enhancing the Photovoltaic Performance of Ternary Organic Solar Cells.

PubMed

Wang, Bei; Fu, Yingying; Yan, Chi; Zhang, Rui; Yang, Qingqing; Han, Yanchun; Xie, Zhiyuan

2018-01-01

The development of non-fullerene acceptor molecules have remarkably boosted power conversion efficiency (PCE) of polymer solar cells (PSCs) due to the improved spectral coverage and reduced energy loss. An introduction of fullerene molecules into the non-fullerene acceptor-based blend may further improve the photovoltaic performance of the resultant ternary PSCs. However, the underlying mechanism is still debatable. Herein, the ternary PSCs based on PBDB-T:ITIC:PC 71 BM blend were fabricated and its PCE was increased to 10.2% compared to 9.2% for the binary PBDB-T:ITIC devices and 8.1% for the PBDB-T:PC 71 BM PSCs. Systematic investigation was carried out to disclose the effect of PC 71 BM on the blend morphology and charge transport behavior. It is found that the PC 71 BM tends to intermix with the PBDB-T donor compared to the ITIC counterpart. A small amount of PC 71 BM in the ternary blend is helpful for ITIC to aggregate and form efficient electron-transport pathways. Accordingly, the electron mobility is increased and the density of electron traps is decreased in the ternary blend in comparison with the PBDB-T:ITIC blend. Finally, the suppressed bimolecular recombination and enhanced charge collection lead to high PCE for the ternary solar cells.

Preparation of Emulsifying Wax/GMO Nanoparticles and Evaluation as a Delivery System for Repurposing Simvastatin in Bone Regeneration.

PubMed

Eskinazi-Budge, Aaron; Manickavasagam, Dharani; Czech, Tori; Novak, Kimberly; Kunzler, James; Oyewumi, Moses O

2018-05-30

Simvastatin (Sim) is a widely known drug in the treatment of hyperlipidemia that has attracted so much attention in bone regeneration based on its potential osteoanabolic effect. However, repurposing of Sim in bone regeneration will require suitable delivery systems that can negate undesirable off-target/side effects. In this study, we have investigated a new lipid nanoparticle (NP) platform that was fabricated using a binary blend of emulsifying wax (Ewax) and glyceryl monooleate (GMO). Using the binary matrix materials, NPs loaded with Sim (0-500 µg/mL) were prepared and showed an average particle size of about 150 nm. NP size stability was dependent on Sim concentration loaded in NPs. The suitability of NPs prepared with the binary matrix materials in Sim delivery for potential application in bone regeneration was supported by biocompatibility in pre-osteoclastic and pre-osteoblastic cells. Additional data demonstrated that biofunctional Sim was released from NPs that facilitated differentiation of osteoblasts (cells that form bones) while inhibiting differentiation of osteoclasts (cells that resorb bones). The overall work demonstrated the preparation of NPs from Ewax/GMO blends and characterization to ascertain potential suitability in Sim delivery for bone regeneration. Additional studies on osteoblast and osteoclast functions are warranted to fully evaluate the efficacy simvastatin-loaded Ewax/GMO NPs using in-vitro and in-vivo approaches.

Hemocompatible polyethersulfone/polyurethane composite membrane for high-performance antifouling and antithrombotic dialyzer.

PubMed

Yin, Zehua; Cheng, Chong; Qin, Hui; Nie, Chuanxiong; He, Chao; Zhao, Changsheng

2015-01-01

Researches on blood purification membranes are fuelled by diverse clinical needs, such as hemodialysis, hemodiafiltration, hemofiltration, plasmapheresis, and plasma collection. To approach high-performance dialyzer, the integrated antifouling and antithrombotic properties are highly necessary for the design/modification of advanced artificial membranes. In this study, we propose and demonstrate that the physical blend of triblock polyurethane (PU) and polyethersulfone (PES) may advance the performance of hemodialysis membranes with greatly enhanced blood compatibility. It was found that the triblock PU could be blended with PES at high ratio owing to their excellent miscibility. The surfaces of the PES/PU composite membranes were characterized using attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, water contact angle measurement, and surface ζ-potentials. The results indicated that the membrane surfaces were assembled with hydrophilic segregation layer owing to the migration of amphiphilic PU segments during membrane preparation, which might confer the composite membranes with superior hemocompatibility. The cross-section scanning electron microscopy images of the composite membranes exhibited structure transformation from finger-like structure to sponge-like structure, which indicated that the composite membrane had tunable porosity and permeability. The further ultrafiltration experiments indicated that the composite membranes showed increased permeability and excellent antifouling ability. The blood compatibility observation indicated that PES/PU composite membranes owned decreased protein adsorption, suppressed platelet adhesion, and prolonged plasma recalcification time. These results indicated that the PES/PU composite membranes exhibited enhanced antifouling and antithrombotic properties than the pristine PES membrane. The strategy may forward the fabrication of blood compatible composite membranes for clinical blood dialysis by using the various functional miscible polymers. © 2014 Wiley Periodicals, Inc.

Mixing, diffusion, and percolation in binary supported membranes containing mixtures of lipids and amphiphilic block copolymers.

PubMed

Gettel, Douglas L; Sanborn, Jeremy; Patel, Mira A; de Hoog, Hans-Peter; Liedberg, Bo; Nallani, Madhavan; Parikh, Atul N

2014-07-23

Substrate-mediated fusion of small polymersomes, derived from mixtures of lipids and amphiphilic block copolymers, produces hybrid, supported planar bilayers at hydrophilic surfaces, monolayers at hydrophobic surfaces, and binary monolayer/bilayer patterns at amphiphilic surfaces, directly responding to local measures of (and variations in) surface free energy. Despite the large thickness mismatch in their hydrophobic cores, the hybrid membranes do not exhibit microscopic phase separation, reflecting irreversible adsorption and limited lateral reorganization of the polymer component. With increasing fluid-phase lipid fraction, these hybrid, supported membranes undergo a fluidity transition, producing a fully percolating fluid lipid phase beyond a critical area fraction, which matches the percolation threshold for the immobile point obstacles. This then suggests that polymer-lipid hybrid membranes might be useful models for studying obstructed diffusion, such as occurs in lipid membranes containing proteins.

Thermal casting process for the preparation of membranes

DOEpatents

Caneba, G.T.M.; Soong, D.S.

1985-07-10

Disclosed is a method for providing anisotropic polymer membrane from a binary polymer/solvent solution using a thermal inversion process. A homogeneous binary solution is cast onto a support and cooled in such a way as to provide a differential in cooling rate across the thickness of the resulting membrane sheet. Isotropic or anisotropic structures of selected porosities can be produced, depending on the initial concentration of polymer in the selected solvent and on the extent of the differential in cooling rate. This differential results in a corresponding gradation in pore size. The method may be modified to provide a working skin by applying a rapid, high-temperature pulse to redissolve a predetermined thickness of the membrane at one of its faces and then freezing the entire structure.

High throughput research and evaporation rate modeling for solvent screening for ethylcellulose barrier membranes in pharmaceutical applications.

PubMed

Schoener, Cody A; Curtis-Fisk, Jaime L; Rogers, True L; Tate, Michael P

2016-10-01

Ethylcellulose is commonly dissolved in a solvent or formed into an aqueous dispersion and sprayed onto various dosage forms to form a barrier membrane to provide controlled release in pharmaceutical formulations. Due to the variety of solvents utilized in the pharmaceutical industry and the importance solvent can play on film formation and film strength it is critical to understand how solvent can influence these parameters. To systematically study a variety of solvent blends and how these solvent blends influence ethylcellulose film formation, physical and mechanical film properties and solution properties such as clarity and viscosity. Using high throughput capabilities and evaporation rate modeling, thirty-one different solvent blends composed of ethanol, isopropanol, acetone, methanol, and/or water were formulated, analyzed for viscosity and clarity, and narrowed down to four solvent blends. Brookfield viscosity, film casting, mechanical film testing and water permeation were also completed. High throughput analysis identified isopropanol/water, ethanol, ethanol/water and methanol/acetone/water as solvent blends with unique clarity and viscosity values. Evaporation rate modeling further rank ordered these candidates from excellent to poor interaction with ethylcellulose. Isopropanol/water was identified as the most suitable solvent blend for ethylcellulose due to azeotrope formation during evaporation, which resulted in a solvent-rich phase allowing the ethylcellulose polymer chains to remain maximally extended during film formation. Consequently, the highest clarity and most ductile films were formed. Employing high throughput capabilities paired with evaporation rate modeling allowed strong predictions between solvent interaction with ethylcellulose and mechanical film properties.

Contribution made by multivariate curve resolution applied to gel permeation chromatography-Fourier transform infrared data for an in-depth characterization of styrene-butadiene rubber blends.

PubMed

Ruckebusch, C; Vilmin, F; Coste, N; Huvenne, J P

2008-07-01

We evaluate the contribution made by multivariate curve resolution-alternating least squares (MCR-ALS) for resolving gel permeation chromatography-Fourier transform infrared (GPC-FT-IR) data collected on butadiene rubber (BR) and styrene butadiene rubber (SBR) blends in order to access in-depth knowledge of polymers along the molecular weight distribution (MWD). In the BR-SBR case, individual polymers differ in chemical composition but share almost the same MWD. Principal component analysis (PCA) gives a general overview of the data structure and attests to the feasibility of modeling blends as a binary system. MCR-ALS is then performed. It allows resolving the chromatographic coelution and validates the chosen methodology. For SBR-SBR blends, the problem is more challenging since the individual elastomers present the same chemical composition. Rank deficiency is detected from the PCA data structure analysis. MCR-ALS is thus performed on column-wise augmented matrices. It brings very useful insight into the composition of the analyzed blends. In particular, a weak change in the composition of individual SBR in the MWD's lowest mass region is revealed.

Polysulfide and bio-based EP additive performance in vegetable vs. paraffinic base oils

USDA-ARS?s Scientific Manuscript database

Twist compression test (TCT) and 4-ball extreme pressure (EP) methods were used to investigate commercial polysulfide (PS) and bio-based polyester (PE) EP additives in paraffinic (150N) and refined soybean (SOY) base oils of similar viscosity. Binary blends of EP additive and base oil were investiga...

CO2 adsorption using TiO2 composite polymeric membranes: A kinetic study.

PubMed

Hafeez, Sarah; Fan, X; Hussain, Arshad; Martín, C F

2015-09-01

CO2 is the main greenhouse gas which causes global climatic changes on larger scale. Many techniques have been utilised to capture CO2. Membrane gas separation is a fast growing CO2 capture technique, particularly gas separation by composite membranes. The separation of CO2 by a membrane is not just a process to physically sieve out of CO2 through the controlled membrane pore size. It mainly depends upon diffusion and solubility of gases, particularly for composite dense membranes. The blended components in composite membranes have a high capability to adsorb CO2. The adsorption kinetics of the gases may directly affect diffusion and solubility. In this study, we have investigated the adsorption behaviour of CO2 in pure and composite membranes to explore the complete understanding of diffusion and solubility of CO2 through membranes. Pure cellulose acetate (CA) and cellulose acetate-titania nanoparticle (CA-TiO2) composite membranes were fabricated and characterised using SEM and FTIR analysis. The results indicated that the blended CA-TiO2 membrane adsorbed more quantity of CO2 gas as compared to pure CA membrane. The high CO2 adsorption capacity may enhance the diffusion and solubility of CO2 in the CA-TiO2 composite membrane, which results in a better CO2 separation. The experimental data was modelled by Pseudo first-order, pseudo second order and intra particle diffusion models. According to correlation factor R(2), the Pseudo second order model was fitted well with experimental data. The intra particle diffusion model revealed that adsorption in dense membranes was not solely consisting of intra particle diffusion. Copyright © 2015. Published by Elsevier B.V.

Mechanically controlling the reversible phase transformation from zinc blende to wurtzite in AlN

DOE PAGES

Li, Zhen; Yadav, Satyesh; Chen, Youxing; ...

2017-04-10

III–V and other binary octet semiconductors often take two phase forms—wurtzite (wz) and zinc blende (zb) crystal structures—with distinct functional performance at room temperature. Here, we investigate how to control the synthesized phase structure to either wz or zb phase by tuning the interfacial strain by taking AlN as a representative III–V compound. Furthermore, by applying in situ mechanical tests at atomic scale in a transmission electron microscope, we observed the reversible phase transformation from zb to wz, and characterized the transition path—the collective glide of Shockley partials on every two {111} planes of the zb AlN.

Regulation of anionic lipids in binary membrane upon the adsorption of polyelectrolyte: A Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Duan, Xiaozheng; Li, Yunqi; Zhang, Ran; Shi, Tongfei; An, Lijia; Huang, Qingrong

2013-06-01

We employ Monte Carlo simulations to investigate the interaction between an adsorbing linear flexible cationic polyelectrolyte and a binary fluid membrane. The membrane contains neutral phosphatidyl-choline, PC) and multivalent anionic (phosphatidylinositol, PIP2) lipids. We systematically study the influences of the solution ionic strength, the chain length and the bead charge density of the polyelectrolyte on the lateral rearrangement and the restricted mobility of the multivalent anionic lipids in the membrane. Our findings show that, the cooperativity effect and the electrostatic interaction of the polyelectrolyte beads can significantly affect the segregation extent and the concentration gradients of the PIP2 molecules, and further cooperate to induce the complicated hierarchical mobility behaviors of PIP2 molecules. In addition, when the polyelectrolyte brings a large amount of charges, it can form a robust electrostatic well to trap all PIP2 and results in local overcharge of the membrane. This work presents a mechanism to explain the membrane heterogeneity formation induced by the adsorption of charged macromolecule.

Highly antifouling and antibacterial performance of poly (vinylidene fluoride) ultrafiltration membranes blending with copper oxide and graphene oxide nanofillers for effective wastewater treatment.

PubMed

Zhao, Chuanqi; Lv, Jinling; Xu, Xiaochen; Zhang, Guoquan; Yang, Yuesuo; Yang, Fenglin

2017-11-01

Innovation and effective wastewater treatment technology is still in great demand given the emerging contaminants frequently spotted from the aqueous environment. By blending with poly (vinylidene fluoride) (PVDF), the strong hydrophilic graphene oxide (GO) and antibacterial copper oxide (Cu x O) were used as nanofillers to develop the novel, highly antifouling composite membranes via phase inversion process in our latest work. The existence and dispersion of GO and Cu x O posed a significant role on morphologies, structures, surface composition and hydrophilicity of the developed composite membranes, confirmed by SEM, TEM, FTIR and XPS in depth characterization. The SEM images showed that the modified membranes presented a lower resistant structure with developed finger-like macrovoids and thin-walled even interconnected sponge-like pores after adding nanofillers, much encouraging membrane permeation. The XPS results revealed that Cu x O contained Cu 2 O and CuO in the developed membrane and the Cu 2 O nanoparticles were dominant accounting for about 79.3%; thus the modified membrane specifically exhibited an efficient antibacterial capacity. Due to the hydrophilic and bactericidal membrane surface, the composite membranes demonstrated an excellent antifouling performance, including higher flux recovery rate, more resistant against accumulated contaminants and lower filtration resistance, especially lower irreversible resistance. The antifouling property, especially anti-irreversible fouling, was significantly improved, showing a significant engineering potential. Copyright © 2017 Elsevier Inc. All rights reserved.

Poly(Lactic Acid) Hemodialysis Membranes with Poly(Lactic Acid)-block-Poly(2-Hydroxyethyl Methacrylate) Copolymer As Additive: Preparation, Characterization, and Performance.

PubMed

Zhu, Lijing; Liu, Fu; Yu, Xuemin; Xue, Lixin

2015-08-19

Poly(lactic acid) (PLA) hemodialysis membranes with enhanced antifouling capability and hemocompatibility were developed using poly(lactic acid)-block-poly(2-hydroxyethyl methacrylate) (PLA-PHEMA) copolymers as the blending additive. PLA-PHEMA block copolymers were synthesized via reversible addition-fragmentation (RAFT) polymerization from aminolyzed PLA. Gel permeation chromatography (GPC) and (1)H-nuclear magnetic resonance ((1)H NMR) were applied to characterize the synthesized products. By blending PLA with the amphiphilic block copolymer, PLA/PLA-PHEMA membranes were prepared by nonsolvent induced phase separation (NIPS) method. Their chemistry and structure were characterized with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and atomic force microscopy (AFM). The results revealed that PLA/PLA-PHEMA membranes with high PLA-PHEMA contents exhibited enhanced hydrophilicity, water permeability, antifouling and hemocompatibility. Especially, when the PLA-PHEMA concentration was 15 wt %, the water flux of the modified membrane was about 236 L m(-2) h(-1). Its urea and creatinine clearance was more than 0.70 mL/min, lysozyme clearance was about 0.50 mL/min, BSA clearance was as less as 0.31 mL/min. All the results suggest that PLA-PHEMA copolymers had served as effective agents for optimizing the property of PLA-based membrane for hemodialysis applications.

Influence of non-covalent modification of multiwalled carbon nanotubes on the crystallization behaviour of binary blends of polypropylene and polyamide 6.

PubMed

Mukhopadhyay, Nabaneeta; Panwar, Ajay S; Kumar, Gulshan; Samajdar, I; Bhattacharyya, Arup R

2015-02-14

Blends of polypropylene (PP) and polyamide 6 (PA6) with multiwalled carbon nanotubes (MWNTs) were prepared using different processing strategies in a twin-screw micro-compounder. The effect of MWNTs on the crystallization behaviour of the PP phase and the PA6 phase of the blend has been investigated through non-isothermal crystallization studies by differential scanning calorimetric analysis. Furthermore, the effect of the addition of the compatibilizer (PP-g-MA) and the modification of MWNTs (m-MWNTs) with a non-covalent organic modifier (Li-salt of 6 amino hexanoic acid, Li-AHA) has also been studied in context to the crystallization behaviour of the PP and PA6 phase in the blend. The crystallization studies have indicated a significant increase in bulk crystallization temperature of the PP phase in the blend in the presence of MWNTs. Moreover, the formation of 'trans-lamellar crystalline' structure consisting of PA6 'trans-crystalline lamellae' on MWNTs surface was facilitated in the case of blends prepared via 'protocol 2' as compared to the corresponding blends prepared via 'protocol 1'. Wide angle X-ray diffraction analysis has showed the existence of a β-polymorph of the PP phase due to incorporation of the PA6 phase in the blend. Addition of MWNTs in the blends has facilitated further β-crystalline structure formation of the PP phase. In the presence of m-MWNTs, a higher β-fraction was observed in the PP phase as compared to the blend with pristine MWNTs. Addition of PP-g-MA has suppressed the β-phase formation in the PP phase in the blend. X-ray bulk texture analysis revealed that incorporation of PA6 as well as pristine/modified MWNTs has influenced the extent of orientation of the PP chains towards specific crystalline planes in various blend compositions of PP and PA6.

Harnessing Active Fins to Segregate Nanoparticles from Binary Mixtures

NASA Astrophysics Data System (ADS)

Liu, Ya; Kuksenok, Olga; Bhattacharya, Amitabh; Ma, Yongting; He, Ximin; Aizenberg, Joanna; Balazs, Anna

2014-03-01

One of the challenges in creating high-performance polymeric nanocomposites for optoelectronic applications, such as bilayer solar cells, is establishing effective and facile routes for controlling the properties of interface and segregation of binary particles with hole conductor particles and electron conductor particles. We model nanocomposites that encompass binary particles and binary blends in a microchannel. An array of oscillating microfins is immersed in the fluid and tethered to the floor of the microchannel; the fluid containing mixture of nanoparticles is driven along the channel by an imposed pressure gradient. During the oscillations, the fins with the specific chemical wetting reach the upper fluid when they are upright and are entirely within the lower stream when they are tilted. We introduce specific interaction between the fins and particulates in the solution. Fins can selectively ``catch'' target nanoparticles within the upper fluid stream and then release them into the lower stream. We focus on different modes of fins motion to optimize selective segregation of particles within binary mixture. Our approach provides an effective means of tailoring the properties and ultimate performance of the composites.

Pretreatment and Membrane Hydrophilic Modification to Reduce Membrane Fouling

PubMed Central

Sun, Wen; Liu, Junxia; Chu, Huaqiang; Dong, Bingzhi

2013-01-01

The application of low pressure membranes (microfiltration/ultrafiltration) has undergone accelerated development for drinking water production. However, the major obstacle encountered in its popularization is membrane fouling caused by natural organic matter (NOM). This paper firstly summarizes the two factors causing the organic membrane fouling, including molecular weight (MW) and hydrophilicity/hydrophobicity of NOM, and then presents a brief introduction of the methods which can prevent membrane fouling such as pretreatment of the feed water (e.g., coagulation, adsorption, and pre-oxidation) and membrane hydrophilic modification (e.g., plasma modification, irradiation grafting modification, surface coating modification, blend modification, etc.). Perspectives of further research are also discussed. PMID:24956947

Structural and water diffusion of poly(acryl amide)/poly(vinyl alcohol) blend films: Experiment and molecular dynamics simulations.

PubMed

Wang, Yanen; Wei, Qinghua; Wang, Shuzhi; Chai, Weihong; Zhang, Yingfeng

2017-01-01

To study the effects of composition ratios and temperature on the diffusion of water molecules in PVA/PAM blend films, five simulation models of PVA/PAM with ten water molecules at different composition ratios (4/0, 3/1, 2/2, 1/3, 0/4) were constructed and simulated by using a molecular dynamics (MD) simulation. The diffusion behavior of water molecules in blends were investigated from the aspects of the diffusion coefficient, free volume, pair correlation function (PCF) and trajectories of water molecules, respectively. And the hydrophilicity of blend composite was studied based on the contact angle and equilibrium water content (EWC) of the blend films. The simulation results show that the diffusion coefficient of water molecules and fractional free volume (FFV) of blend membranes increase with the addition of PAM, and a higher temperature can also improve the diffusion of water molecules. Additionally, the analysis of PCFs reveals the main reason why the diffusion coefficient of water in blend system increases with the addition of PAM. The measurement results of contact angle and EWC of blend films indicate that the hydrophilicity of blend films decreases with the addition of PAM, but the EWC of blends increases with the addition of PAM. Copyright © 2016 Elsevier Inc. All rights reserved.

Preparation and characterization of amphiphilic copolymer PVDF-g-PMABS and its application in improving hydrophilicity and protein fouling resistance of PVDF membrane

NASA Astrophysics Data System (ADS)

Chen, Fengtao; Shi, Xingxing; Chen, Xiaobing; Chen, Wenxing

2018-01-01

A facile strategy to improve the hydrophilicity and the antifouling properties of poly(vinylidene fluoride) (PVDF) membranes, a functional monomer of 4-methacrylamidobenzenesulfonic acid (MABS), was designed and synthesized through the amidation reaction between 2-methylacryloyl chloride and sulfanilic acid. Utilizing PVDF and the obtained MABS as reaction monomers, a novel amphiphilic copolymer was firstly prepared by radical polymerization method. The resulting PVDF-g-PMABS was used as a hydrophilic additive in the fabrication of PVDF porous membranes via immersion precipitation process. The surface chemical compositions and structure morphologies of as-prepared blend membranes (PVDF-g-PMABS/PVDF) were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. Contact angle measurement and cross-flow permeation test were employed to evaluate the hydrophilicity and antifouling properties of the membranes. It was found that the blend membrane with 4 wt.% PVDF-g-PMABS exhibited a noticeable pure water flux (136.34 L m-2 h-1) and a remarkable flux recovery ratio (FRR) of 98.60% in comparison with the pristine PVDF membrane (63.37 L m-2 h-1 and 38.67%, respectively). The enhanced performance was attributed to the synergetic effects of the strong hydrogen bonding force and the electrostatic repulsion of sulfonic groups against the protein foulants.

Binary blend of glyceryl monooleate and glyceryl monostearate for magnetically induced thermo-responsive local drug delivery system.

PubMed

Mengesha, Abebe E; Wydra, Robert J; Hilt, J Zach; Bummer, Paul M

2013-12-01

To develop a novel monoglycerides-based thermal-sensitive drug delivery system, specifically for local intracavitary chemotherapy. Lipid matrices containing mixtures of glyceryl monooleate (GMO) and glyceryl monostearate (GMS) were evaluated for their potential application as magnetically induced thermo-responsive local drug delivery systems using a poorly water-soluble model drug, nifedipine (NF). Oleic acid-modified iron oxide (OA-Fe3O4) nanoparticles were embedded into the GMO-GMS matrix for remote activation of the drug release using an alternating magnetic field (AMF). The crystallization behavior of binary blends of GMO and GMS as characterized by DSC did show temperature dependent phase transition. GMO-GMS (75:25 wt%) blend showed a melting (T m ) and crystallization (T c ) points at 42°C and 37°C, respectively indicating the potential of the matrix to act as an 'on-demand' drug release. The matrix released only 35% of the loaded drug slowly in 10 days at 37°C whereas 96% release was obtained at 42°C. A concentration of 0.5% OA-Fe3O4 heated the matrix to 42.3 and 45.5°C within 5 min and 10 min of AMF exposure, respectively. The in vitro NF release profiles form the monoglycerides matrix containing 0.5% OA-Fe3O4 nanoparticles after AMF activation confirmed the thermo-responsive nature of the matrix that could provide pulsatile drug release 'on-demand'.

Biomimetic porous high-density polyethylene/polyethylene- grafted-maleic anhydride scaffold with improved in vitro cytocompatibility.

PubMed

Sharma, Swati; Bhaskar, Nitu; Bose, Surjasarathi; Basu, Bikaramjit

2018-05-01

A major challenge for tissue engineering is to design and to develop a porous biocompatible scaffold, which can mimic the properties of natural tissue. As a first step towards this endeavour, we here demonstrate a distinct methodology in biomimetically synthesized porous high-density polyethylene scaffolds. Co-extrusion approach was adopted, whereby high-density polyethylene was melt mixed with polyethylene oxide to form an immiscible binary blend. Selective dissolution of polyethylene oxide from the biphasic system revealed droplet-matrix-type morphology. An attempt to stabilize such morphology against thermal and shear effects was made by the addition of polyethylene- grafted-maleic anhydride as a compatibilizer. A maximum ultimate tensile strength of 7 MPa and elastic modulus of 370 MPa were displayed by the high-density polyethylene/polyethylene oxide binary blend with 5% maleated polyethylene during uniaxial tensile loading. The cell culture experiments with murine myoblast C2C12 cell line indicated that compared to neat high-density polyethylene and high-density polyethylene/polyethylene oxide, the high-density polyethylene/polyethylene oxide with 5% polyethylene- grafted-maleic anhydride scaffold significantly increased muscle cell attachment and proliferation with distinct elongated threadlike appearance and highly stained nuclei, in vitro. This has been partly attributed to the change in surface wettability property with a reduced contact angle (∼72°) for 5% PE- g-MA blends. These findings suggest that the high-density polyethylene/polyethylene oxide with 5% polyethylene- grafted-maleic anhydride can be treated as a cell growth substrate in bioengineering applications.

Improved monitoring of oriental fruit moth (Lepidoptera: Tortricidae) with terpinyl acetate plus acetic acid membrane lures

USDA-ARS?s Scientific Manuscript database

Male and female moth catches of Grapholita molesta (Busck) in traps were evaluated in stone and pome fruit orchards untreated or treated with sex pheromones for mating disruption in Uruguay, Argentina, Chile, USA, and Italy from 2015 - 2017. Trials evaluated various blends loaded into either membran...

Effect of deacetylation on property of electrospun chitosan/PVA nanofibrous membrane and removal of methyl orange, Fe(III) and Cr(VI) ions.

PubMed

Habiba, Umma; Siddique, Tawsif A; Talebian, Sepehr; Lee, Jacky Jia Li; Salleh, Areisman; Ang, Bee Chin; Afifi, Amalina M

2017-12-01

In this study, effect of degree of deacetylation on property and adsorption capacity of chitosan/polyvinyl Alcohol electrospun membrane has been investigated. Resulting nanofibers were characterized by FESEM, FTIR, XRD, TGA, tensile testing, weight loss test and adsorption test. FESEM result shows, finer nanofiber was fabricated from 42h hydrolyzed chitosan and PVA blend solution. FTIR and XRD result showed a strong interaction between chitosan and polyvinyl alcohol. Higher tensile strength was observed for the nanofiber having 42h hydrolyzed chitosan. Blend solution of chitosan/PVA having low DD chitosan had higher viscosity. The nanofibrous membrane was stable in distilled water, acidic and basic medium. The isotherm study shows that the adsorption capacity (q m ) of nanofiber containing higher DD chitosan was higher for Cr(VI). In contrary, the membrane containing chitosan with lower DD showed the higher adsorption capacity for Fe(III) and methyl orange. Moreover, the effect of DD on removal percentage of adsorbate was dependent on the initial concentration of the adsorbate. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of miscibility phenomenon on crystalline polymorph transition in poly(vinylidene fluoride)/acrylic rubber/clay nanocomposite hybrid.

PubMed

Abolhasani, Mohammad Mahdi; Naebe, Minoo; Jalali-Arani, Azam; Guo, Qipeng

2014-01-01

In this paper, intercalation of nanoclay in the miscible polymer blend of poly(vinylidene fluoride) (PVDF) and acrylic rubber(ACM) was studied. X-ray diffraction was used to investigate the formation of nanoscale polymer blend/clay hybrid. Infrared spectroscopy and X-ray analysis revealed the coexistence of β and γ crystalline forms in PVDF/Clay nanocomposite while α crystalline form was found to be dominant in PVDF/ACM/Clay miscible hybrids. Flory-Huggins interaction parameter (B) was used to further explain the miscibility phenomenon observed. The B parameter was determined by combining the melting point depression and the binary interaction model. The estimated B values for the ternary PVDF/ACM/Clay and PVDF/ACM pairs were all negative, showing both proper intercalation of the polymer melt into the nanoclay galleries and the good miscibility of PVDF and ACM blend. The B value for the PVDF/ACM blend was almost the same as that measured for the PVDF/ACM/Clay hybrid, suggesting that PVDF chains in nanocomposite hybrids interact with ACM chains and that nanoclay in hybrid systems is wrapped by ACM molecules.

Miscibility Studies on Polymer Blends Modified with Phytochemicals

NASA Astrophysics Data System (ADS)

Chandrasekaran, Neelakandan; Kyu, Thein

2009-03-01

The miscibility studies related to an amorphous poly(amide)/poly(vinyl pyrrolidone) [PA/PVP] blend with a crystalline phytochemical called ``Mangiferin'' is presented. Phytochemicals are plant derived chemicals which intrinsically possess multiple salubrious properties that are associated with prevention of diseases such as cancer, diabetes, cardiovascular disease, and hypertension. Incorporation of phytochemicals into polymers has shown to have very promising applications in wound healing, drug delivery, etc. The morphology of these materials is crucial to applications like hemodialysis, which is governed by thermodynamics and kinetics of the phase separation process. Hence, miscibility studies of PA/PVP blends with and without mangiferin have been carried out using dimethyl sulfoxide as a common solvent. Differential scanning calorimetry studies revealed that the binary PA/PVP blends were completely miscible at all compositions. However, the addition of mangiferin has led to liquid-liquid phase separation and liquid-solid phase transition in a composition dependent manner. Fourier transformed infrared spectroscopy was undertaken to determine specific interaction between the polymer constituents and the role of possible hydrogen bonding among three constituents will be discussed.

Property tuning of poly(lactic acid)/cellulose bio-composites through blending with modified ethylene-vinyl acetate copolymer.

PubMed

Pracella, Mariano; Haque, Md Minhaz-Ul; Paci, Massimo; Alvarez, Vera

2016-02-10

The effect of addition of an ethylene-vinyl acetate copolymer modified with glycidyl methacrylate (EVA-GMA) on the structure and properties of poly(lactic acid) (PLA) composites with cellulose micro fibres (CF) was investigated. Binary (PLA/CF) and ternary (PLA/EVA-GMA/CF) composites obtained by melt mixing in Brabender mixer were analysed by SEM, POM, WAXS, DSC, TGA and tensile tests. The miscibility and morphology of PLA/EVA-GMA blends were first examined as a function of composition: a large rise of PLA spherulite growth rate in the blends was discovered with increasing the EVA-GMA content (0-30 wt%) in the isothermal crystallization both from the melt and the solid state. PLA/EVA-GMA/CF ternary composites displayed improved adhesion and dispersion of fibres into the matrix as compared to PLA/CF system. Marked changes of thermodynamic and tensile parameters, as elastic modulus, strength and elongation at break were observed for the composites, depending on blend composition, polymer miscibility and fibre-matrix chemical interactions at the interface. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hollow fibers of poly(lactide-co-glycolide) and poly(ε-caprolactone) blends for vascular tissue engineering applications.

PubMed

Diban, Nazely; Haimi, Suvi; Bolhuis-Versteeg, Lydia; Teixeira, Sandra; Miettinen, Susanna; Poot, André; Grijpma, Dirk; Stamatialis, Dimitrios

2013-05-01

At present the manufacture of small-diameter blood vessels is one of the main challenges in the field of vascular tissue engineering. Currently available vascular grafts rapidly fail due to development of intimal hyperplasia and thrombus formation. Poly(lactic-co-glycolic acid) (PLGA) hollow fiber (HF) membranes have previously been proposed for this application, but as we show in the present work, they have an inhibiting effect on cell proliferation and rather poor mechanical properties. To overcome this we prepared HF membranes via phase inversion using blends of PLGA with poly(ε-caprolactone) (PCL). The influence of polymer composition on the HF physicochemical properties (topography, water transport and mechanical properties) and cell attachment and proliferation were studied. Our results show that only the ratio PCL/PLGA of 85/15 (PCL/PLGA85/15) yielded a miscible blend after processing. A higher PLGA concentration in the blend led to immiscible PCL/PLGA phase-separated HFs with an inhomogeneous morphology and variation in the cell culture results. In fact, the PCL/PLGA85/15 blend, which had the most homogeneous morphology and suitable pore structure, showed better human adipose stem cell (hASC) attachment and proliferation compared with the homopolymers. This, combined with the good mechanical and transport properties, makes them potentially useful for the development of small-caliber vascular grafts. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Fundamental characteristics study of anion-exchange PVDF-SiO(2) membranes.

PubMed

Zuo, Xingtao; Shi, Wenxin; Yu, Shuili; He, Jiajie

2012-01-01

A new type of poly(vinylidene fluoride)(PVDF)-SiO(2) hybrid anion-exchange membrane was prepared by blending method. The anion-exchange groups were introduced by the reaction of epoxy groups with trimethylamine (TMA). Contact angle between water and the membrane surface was measured to characterize the hydrophilicity change of the membrane surface. The effects of nano-sized SiO(2) particles in the membrane-forming materials on the membrane mechanical properties and conductivity were also investigated. The experimental results indicated that PVDF-SiO(2) anion-exchange membranes exhibited better water content, ion-exchange capacity, conductivity and mechanic properties, and so may find potential applications in alkaline membrane fuel cells and water treatment processes.

Fouling Resistant CA/PVA/TiO2 Imprinted Membranes for Selective Recognition and Separation Salicylic Acid from Waste Water

PubMed Central

Yu, Xiaopeng; Mi, Xueyang; He, Zhihui; Meng, Minjia; Li, Hongji; Yan, Yongsheng

2017-01-01

Highly selective cellulose acetate (CA)/poly (vinyl alcohol) (PVA)/titanium dioxide (TiO2) imprinted membranes were synthesized by phase inversion and dip coating technique. The CA blend imprinted membrane was synthesized by phase inversion technique with CA as membrane matrix, polyethyleneimine (PEI) as the functional polymer, and the salicylic acid (SA) as the template molecule. The CA/PVA/TiO2 imprinted membranes were synthesized by dip coating of CA blend imprinted membrane in PVA and different concentration (0.05, 0.1, 0.2, 0.4 wt %) of TiO2 nanoparticles aqueous solution. The SEM analysis showed that the surface morphology of membrane was strongly influenced by the concentration of TiO2 nanoparticles. Compared with CA/PVA-TiO2(0.05, 0.1, 0.2%)-MIM, the CA/PVA-TiO2(0.4%)-MIM possessed higher membrane flux, kinetic equilibrium adsorption amount, binding capacity and better selectivity for SA. It was found that the pseudo-second-order kinetic model was studied to describe the kinetic of CA/PVA-TiO2(0.2%)-MIM judging by multiple regression analysis. Adsorption isotherm analysis indicated that the maximum adsorption capacity for SA were 24.43 mg g−1. Moreover, the selectivity coefficients of CA/PVA-TiO2 (0.2%)-MIM for SA relative to p-hydroxybenzoic acid (p-HB) and methyl salicylate (MS) were 3.87 and 3.55, respectively. PMID:28184369

Low Crossover Polymer Electrolyte Membranes for Direct Methanol Fuel Cells

NASA Technical Reports Server (NTRS)

Prakash, G. K. Surya; Smart, Marshall; Atti, Anthony R.; Olah, George A.; Narayanan, S. R.; Valdez, T.; Surampudi, S.

1996-01-01

Direct Methanol Fuel Cells (DMFC's) using polymer electrolyte membranes are promising power sources for portable and vehicular applications. State of the art technology using Nafion(R) 117 membranes (Dupont) are limited by high methanol permeability and cost, resulting in reduced fuel cell efficiencies and impractical commercialization. Therefore, much research in the fuel cell field is focused on the preparation and testing of low crossover and cost efficient polymer electrolyte membranes. The University of Southern California in cooperation with the Jet Propulsion Laboratory is focused on development of such materials. Interpenetrating polymer networks are an effective method used to blend polymer systems without forming chemical links. They provide the ability to modify physical and chemical properties of polymers by optimizing blend compositions. We have developed a novel interpenetrating polymer network based on poly (vinyl - difluoride)/cross-linked polystyrenesulfonic acid polymer composites (PVDF PSSA). Sulfonation of polystyrene accounts for protonic conductivity while the non-polar, PVDF backbone provides structural integrity in addition to methanol rejection. Precursor materials were prepared and analyzed to characterize membrane crystallinity, stability and degree of interpenetration. USC JPL PVDF-PSSA membranes were also characterized to determine methanol permeability, protonic conductivity and sulfur distribution. Membranes were fabricated into membrane electrode assemblies (MEA) and tested for single cell performance. Tests include cell performance over a wide range of temperatures (20 C - 90 C) and cathode conditions (ambient Air/O2). Methanol crossover values are measured in situ using an in-line CO2 analyzer.

Analysis and estimation of service life of corrosion prevention materials using diffusion, resistivity and accelerated curing for new bridge structures : volume 1 : corrosion prevention materials (monitoring and forensic examination).

DOT National Transportation Integrated Search

2013-12-01

This investigation compiles the results describing the performance of: a) reinforced concrete specimens cast with : 0.37 water to cementitious (w/cm) and binary blends of high performance concrete; the specimens have been : exposed to seawater wet/dr...

40 CFR 1065.370 - CLD CO2 and H2O quench verification.

Code of Federal Regulations, 2013 CFR

2013-07-01

... gas divider that blends binary span gases with zero gas as the diluent and meets the specifications in... the maximum NO concentration expected during emission testing. (6) Zero and span the CLD analyzer... divider. Connect the NO span gas to the span port of the gas divider; connect a zero gas to the diluent...

40 CFR 1065.370 - CLD CO2 and H2O quench verification.

Code of Federal Regulations, 2012 CFR

2012-07-01

... gas divider that blends binary span gases with zero gas as the diluent and meets the specifications in... the maximum NO concentration expected during emission testing. (6) Zero and span the CLD analyzer... divider. Connect the NO span gas to the span port of the gas divider; connect a zero gas to the diluent...

40 CFR 1065.370 - CLD CO2 and H2O quench verification.

Code of Federal Regulations, 2014 CFR

2014-07-01

... gas divider that blends binary span gases with zero gas as the diluent and meets the specifications in... the maximum NO concentration expected during emission testing. (6) Zero and span the CLD analyzer... divider. Connect the NO span gas to the span port of the gas divider; connect a zero gas to the diluent...

40 CFR 1065.370 - CLD CO2 and H2O quench verification.

Code of Federal Regulations, 2011 CFR

2011-07-01

... gas divider that blends binary span gases with zero gas as the diluent and meets the specifications in... the maximum NO concentration expected during emission testing. (6) Zero and span the CLD analyzer... divider. Connect the NO span gas to the span port of the gas divider; connect a zero gas to the diluent...

Iron K lines from low-mass X-ray binaries

NASA Technical Reports Server (NTRS)

Kallman, T.; White, N. E.

1989-01-01

Models are presented for the 6-7 keV iron line emission from low-mass X-ray binaries. A simplified model for an accretion disk corona is used to examine the dependence of the observable line properties, line width and mean energy, on the radial distance of the emission region from the X-ray source, and on the fraction of the X-rays from the source which reach the disk surface. The effects of blending of multiple line components and of Comptonization of the line profile are included in numerical calculations of the emitted profile shape. The results of these calculations, when compared with the line properties observed from several low-mass X-ray binaries, suggest that the broadening is dominated either by rotation or by Compton scattering through a greater optical depth than is expected from an accretion disk corona.

Influence of Surface Energy on Organic Alloy Formation in Ternary Blend Solar Cells Based on Two Donor Polymers.

PubMed

Gobalasingham, Nemal S; Noh, Sangtaik; Howard, Jenna B; Thompson, Barry C

2016-10-05

The compositional dependence of the open-circuit voltage (V oc ) in ternary blend bulk heterojunction (BHJ) solar cells is correlated with the miscibility of polymers, which may be influenced by a number of attributes, including crystallinity, the random copolymer effect, or surface energy. Four ternary blend systems featuring poly(3-hexylthiophene-co-3-(2-ethylhexyl)thiophene) (P3HT 75 -co-EHT 25 ), poly(3-hexylthiophene-co-(hexyl-3-carboxylate)), herein referred to as poly(3-hexylthiophene-co-3-hexylesterthiophene) (P3HT 50 -co-3HET 50 ), poly(3-hexylthiophene-thiophene-diketopyrrolopyrrole) (P3HTT-DPP-10%), and an analog of P3HTT-DPP-10% with 40% of 3-hexylthiophene exchanged for 2-(2-methoxyethoxy)ethylthiophen-2-yl (3MEO-T) (featuring an electronically decoupled oligoether side-chain), referred to as P3HTTDPP-MEO40%, are explored in this work. All four polymers are semicrystalline and rich in rr-P3HT content and perform well in binary devices with PC 61 BM. Except for P3HTTDPP-MEO40%, all polymers exhibit similar surface energies (∼21-22 mN/m). P3HTTDPP-MEO40% exhibits an elevated surface energy of around 26 mN/m. As a result, despite the similar optoelectronic properties and binary solar cell performance of P3HTTDPP-MEO40% compared to P3HTT-DPP-10%, the former exhibits a pinned V oc in two different sets of ternary blend devices. This is a stark contrast to previous rr-P3HT-based systems and demonstrates that surface energy, and its influence on miscibility, plays a critical role in the formation of organic alloys and can supersede the influence of crystallinity, the random copolymer effect, similar backbone structures, and HOMO/LUMO considerations. Therefore, we confirm surface energy compatibility as a figure-of-merit for predicting the compositional dependence of the V oc in ternary blend solar cells and highlight the importance of polymer miscibility in organic alloy formation.

Influence of electrostatic interactions on the morphology and properties of blends containing perfluorinated ionomers

NASA Astrophysics Data System (ADS)

Taylor, Eric Paul

2002-01-01

The first goal of this research project was to investigate the influence of the electrostatic interactions within the ion-containing domains of Nafion RTM perfluorosulfonate ionomer (PFSI) on the morphology and resultant properties of blend systems with poly(propylene imine) dendrimers of a variety of generational sizes and poly(vinylidene fluoride) (PVDF). Perfluorosulfonate ionomers (PFSIs) are a commercially successful class of semi-crystalline, ion-containing polymers whose most extensive application is in use as a polymer electrolytic membrane in fuel cell applications. NafionRTM was blended and high temperature solution processed with poly(propylene imine) dendrimer as the minor component in order to increase the efficiency of direct methanol fuel cells by decreasing methanol crossover without significant loss of protonic conductivity. The preferential insertion of the dendrimer into the ionic cluster due to proton transfer reactions and the creation of ammonium-sulfonate ion pairs served to alter the transport properties through the ionic network of the membrane. In the second major system investigated, blends of poly(vinylidene fluoride) (PVDF) with NafionRTM, a perfluorosulfonate ionomer, have been prepared and examined in terms of the crystallization kinetics and crystal morphology of the PVDF component in the blend. DSC analysis showed faster rates of bulk crystallization when PVDF was crystallized in the presence of Na+-form NafionRTM suggesting a high degree of phaseseparation in this blend system and an increase in the nucleation density. NafionRTM neutralized with alkylammonium-form counterions display an increase in blend compatibility with PVDF with an increase in the alkylammonium counterion size. As the alkylammonium counterion size increases, the strength of the electrostatic network within the ionic domains of Nafion RTM decrease resulting in a reduction in the driving force for ionic aggregation. Thus, a decrease is observed in the crystal growth rate and nucleation density of the PVDF component of the blend as the size of the alkylammonium-form counterion increases. This study demonstrates that the type of neutralizing counterion of the NafionRTM component has a dramatic impact on blend compatibility and the crystallization kinetics of the PVDF component within NafionRTM/PVDF blends. In addition, higher phase mixing with the alkylammonium-form NafionRTM component leads to an increase in the PVDF polar polymorphs.

Study on property and stability mechanism of LAB-AEO-4 system

NASA Astrophysics Data System (ADS)

Song, Kaifei; Ge, Jijiang; Wang, Yang; Zhang, Guicai; Jiang, Ping

2017-04-01

The behaviors of binary blending systems of fatty alcohol polyoxyethylene ether (AEO-4) blended with the laurel amide betaine (LAB) was investigated at 80°C,the results indicated that the optimal ratio of the mixed system of LAB-AEO-4 was 5:2. The stability mechanism of LAB-AEO-4 system was analyzed from three aspects of dynamic surface tension,gas permeation rate and surface rheology.The results showed that the tension of mixed system was easier to achieve balance,the constant of gas permeation rate of the mixed system decreased by about 7% and the elastic modulus and dilational modulus increased by about 2 times compared with the single LAB system.

Unraveling Structure-Property Relationships in Polymer Blends for Intelligent Materials Design

NASA Astrophysics Data System (ADS)

Irwin, Matthew Tyler

Block polymers provide an accessible route to structured, composite materials by combining two or more components with disparate mechanical, chemical, and electrical properties into a single bulk material with nanoscale domains. However, the characteristic lengthscale of these systems is limited, and the choice of components is restricted to those that are able to undergo microstructural ordering at accessible temperatures. This thesis details routes to overcoming these limitations through the addition of a lithium salt, a blend of homopolymers, or both. Chapter 2 describes a study wherein complex sphere phases such as the Frank-Kasper sigma phase can be observed in otherwise disordered asymmetric block polymers through the addition of a lithium salt. Chapter 3 discusses the development and characterization of a ternary polymer blend of an AB diblock copolymer and A and B homopolymers doped with a lithium salt. Detailed characterization showed that doping blends that are otherwise disordered with lithium salt induced microstructural ordering and largely recovers the phase behavior of traditional ternary polymer blends. A systematic study of the ionic conductivity of the blends at a fixed salt concentration demonstrates that, at a given composition, disordered, yet highly structured blends consistently exhibit better conductivity than polycrystalline morphologies with long range order. Chapter 4 extends the methodology of Chapter 3 and details a systematic study of the effects of cross-linker concentration on the performance of polymer electrolyte membranes produced via polymerization-induced microphase separation that exhibit a highly structured, globally disordered microstructure. Finally, Chapter 5 details efforts to develop a water filtration membrane using a polyethylene template derived from a polymeric bicontinuous microemulsion. Throughout all of this work, the goal is to better understand structure-property relationships at the molecular level in order to ultimately inform design criteria for materials where simultaneous control over morphology and mechanical, chemical, or electrical properties is important.

Moisture-Mediated Interactions Between Amorphous Maltodextrins and Crystalline Fructose.

PubMed

Thorat, Alpana; Marrs, Krystin N; Ghorab, Mohamed K; Meunier, Vincent; Forny, Laurent; Taylor, Lynne S; Mauer, Lisa J

2017-05-01

The effects of coformulating amorphous maltodextrins (MDs) and crystalline fructose, a deliquescent solid, on the moisture sorption, deliquescence point (RH 0 ), and glass transition temperature (T g ) behaviors were determined. Moisture sorption profiles of binary fructose:MD mixtures and individual ingredients were generated using controlled relative humidity (RH) desiccators and by dynamic vapor sorption techniques. Blends exhibited synergistic moisture uptake at RHs below the RH 0 of fructose, attributed to partial dissolution of fructose in plasticized MD matrices without a significant reduction in the RH 0 of the undissolved fructose. Increasing storage temperature decreased the onset RH for moisture sorption synergy. At all storage RHs, the measured T g (2nd scan) was significantly reduced in fructose:MD mixtures compared to individual MDs, and was related to both the synergistic moisture uptake in the blends and heat-induced ternary fructose-MD-water interactions in the differential scanning calorimeter. Differences were found between the behavior of fructose:MD blends and previous reports of sucrose:MD and NaCl:MD blends, caused in part by the lower RH 0 of fructose. The enhanced moisture sorption in blends of deliquescent and amorphous ingredients could lead to problematic moisture-induced changes if storage conditions are not controlled. © 2017 Institute of Food Technologists®.

Au particle formation on the electron beam induced membrane

NASA Astrophysics Data System (ADS)

Choi, Seong Soo; Park, Myoung Jin; Han, Chul Hee; Oh, Sae-Joong; Kim, Sung-In; Park, Nam Kyou; Park, Doo-Jae; Choi, Soo Bong; Kim, Yong-Sang

2017-02-01

Recently the single molecules such as protein and deoxyribonucleic acid (DNA) have been successfully characterized by using a portable solidstate nanopore (MinION) with an electrical detection technique. However, there have been several reports about the high error rates of the fabricated nanopore device, possibly due to an electrical double layer formed inside the pore channel. The current DNA sequencing technology utilized is based on the optical detection method. In order to utilize the current optical detection technique, we will present the formation of the Au nano-pore with Au particle under the various electron beam irradiations. In order to provide the diffusion of Au atoms, a 2 keV electron beam irradiation has been performed During electron beam irradiations by using field emission scanning electron microscopy (FESEM), Au and C atoms would diffuse together and form the binary mixture membrane. Initially, the Au atoms diffused in the membrane are smaller than 1 nm, below the detection limit of the transmission electron microscopy (TEM), so that we are unable to observe the Au atoms in the formed membrane. However, after several months later, the Au atoms became larger and larger with expense of the smaller particles: Ostwald ripening. Furthermore, we also observe the Au crystalline lattice structure on the binary Au-C membrane. The formed Au crystalline lattice structures were constantly changing during electron beam imaging process due to Spinodal decomposition; the unstable thermodynamic system of Au-C binary membrane. The fabricated Au nanopore with an Au nanoparticle can be utilized as a single molecule nanobio sensor.

Application of Novel Anion-Exchange Blend Membranes (AEBMs) to Vanadium Redox Flow Batteries.

PubMed

Cho, Hyeongrae; Krieg, Henning M; Kerres, Jochen A

2018-06-19

Both cation-exchange membranes and anion-exchange membranes are used as ion conducting membranes in vanadium redox flow batteries (VRFBs). Anion-exchange membranes (AEMs) are applied in vanadium redox flow batteries due to the high blocking property of vanadium ions via the Donnan exclusion effect. In this study, novel anion-exchange blend membranes (AEBMs) were prepared, characterized, and applied in VRFBs. Bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide), poly[(1-(4,4′-diphenylether)-5-oxybenzimidazole)-benzimidazole] (PBI-OO) and sulfonated polyether sulfone polymer were combined to prepare 3-component AEBMs with 1,2,4,5-tetramethylimidazole (TMIm) for quaternization. 3-component AEBMs showed significantly enhanced chemical and mechanical properties compared with those of 2-component AEBMs, resulting in an improved performance in VRFBs. The compositions of the anion-exchange polymers in 3-component AEBMs were systematically varied to optimize the AEBMs for the redox-flow battery application. While the 3-component AEBMs showed comparable efficiencies with Nafion ® 212 membranes, they displayed improved vanadium ions cross-over as was confirmed by open circuit voltage tests and capacity fade tests conducted in VRFBs. In addition, one of the synthesized 3-component AEBM had a superior coulombic efficiency and capacity retention in a charging⁻discharging test over 300 cycles at a current density of 40 mA/cm². It can thus be concluded that 3-component AEBMs are promising candidates for long-term operation in VRFBs.

Structural Transformation of Diblock Copolymer/Homopolymer Assemblies by Tuning Cylindrical Confinement and Interfacial Interactions.

PubMed

Xu, Jiangping; Wang, Ke; Liang, Ruijing; Yang, Yi; Zhou, Huamin; Xie, Xiaolin; Zhu, Jintao

2015-11-17

In this study, we report the controllable structural transformation of block copolymer/homopolymer binary blends in cylindrical nanopores. Polystyrene-b-poly(4-vinylpyridine)/homopolystyrene (SVP/hPS) nanorods (NRs) can be fabricated by pouring the polymers into an anodic aluminum oxide (AAO) channel and isolated by selective removal of the AAO membrane. In this two-dimensional (2D) confinement, SVP self-assembles into NRs with concentric lamellar structure, and the internal structure can be tailored with the addition of hPS. We show that the weight fraction and molecular weight of hPS and the diameter of the channels can significantly affect the internal structure of the NRs. Moreover, mesoporous materials with tunable pore shape, size, and packing style can be prepared by selective solvent swelling of the structured NRs. In addition, these NRs can transform into spherical structures through solvent-absorption annealing, triggering the conversion from 2D to 3D confinement. More importantly, the transformation dynamics can be tuned by varying the preference property of surfactant to the polymers. It is proven that the shape and internal structure of the polymer particles are dominated by the interfacial interactions governed by the surfactants.

The scent of mixtures: rules of odour processing in ants

PubMed Central

Perez, Margot; Giurfa, Martin; d'Ettorre, Patrizia

2015-01-01

Natural odours are complex blends of numerous components. Understanding how animals perceive odour mixtures is central to multiple disciplines. Here we focused on carpenter ants, which rely on odours in various behavioural contexts. We studied overshadowing, a phenomenon that occurs when animals having learnt a binary mixture respond less to one component than to the other, and less than when this component was learnt alone. Ants were trained individually with alcohols and aldehydes varying in carbon-chain length, either as single odours or binary mixtures. They were then tested with the mixture and the components. Overshadowing resulted from the interaction between chain length and functional group: alcohols overshadowed aldehydes, and longer chain lengths overshadowed shorter ones; yet, combinations of these factors could cancel each other and suppress overshadowing. Our results show how ants treat binary olfactory mixtures and set the basis for predictive analyses of odour perception in insects. PMID:25726692

NIR techniques create added values for the pellet and biofuel industry.

PubMed

Lestander, Torbjörn A; Johnsson, Bo; Grothage, Morgan

2009-02-01

A 2(3)-factorial experiment was carried out in an industrial plant producing biofuel pellets with sawdust as feedstock. The aim was to use on-line near infrared (NIR) spectra from sawdust for real time predictions of moisture content, blends of sawdust and energy consumption of the pellet press. The factors varied were: drying temperature and wood powder dryness in binary blends of sawdust from Norway spruce and Scots pine. The main results were excellent NIR calibration models for on-line prediction of moisture content and binary blends of sawdust from the two species, but also for the novel finding that the consumption of electrical energy per unit pelletized biomass can be predicted by NIR reflectance spectra from sawdust entering the pellet press. This power consumption model, explaining 91.0% of the variation, indicated that NIR data contained information of the compression and friction properties of the biomass feedstock. The moisture content model was validated using a running NIR calibration model in the pellet plant. It is shown that the adjusted prediction error was 0.41% moisture content for grinded sawdust dried to ca. 6-12% moisture content. Further, although used drying temperatures influenced NIR spectra the models for drying temperature resulted in low prediction accuracy. The results show that on-line NIR can be used as an important tool in the monitoring and control of the pelletizing process and that the use of NIR technique in fuel pellet production has possibilities to better meet customer specifications, and therefore create added production values.

Synthesis of polyphosphazenes with sulfonimide side groups

DOEpatents

Allcock, Harry R.; Hofmann,; Michael A.; Ambler, Catherine M.; Andrew, Maher E.; Wood, Richard M.; Welna, Daniel T.

2010-07-27

The invention relates to sulfonimide bearing phenolic compounds and the use of those compounds to produce polyphosphazenes functionalized by one or more of those compounds alone, or in combination with cosubstituents. The invention also relates to blends of sulfonimide functionalized phosphazene polymers with other polymers, membranes formed of the functionalized polymers, and the use of those membranes in devices such as fuel cells.

Production and characterization of thermoplastic cassava starch, functionalized poly(lactic acid), and their reactive compatibilized blends

NASA Astrophysics Data System (ADS)

Detyothin, Sukeewan

Cassava starch was blended with glycerol using a co-rotating twin-screw extruder (TSE). Thermoplastic cassava starch (TPCS) at a ratio of 70/30 by weight of cassava/glycerol was selected and further blended with other polymers. TPCS sheets made from compression molding had low tensile strength (0.45 +/- 0.05 MPa) and Young's modulus (1.24 +/- 0.58 MPa), but moderate elongation at break (83.0 +/- 0.18.6%), medium level of oxygen permeability, and high water vapor permeability with a very high rate of water absorption. TPCS was blended with poly(lactic acid) (PLA) at various ratios by using a TSE. The blend resins exhibited good properties such as increased thermal stability (Tmax) and crystallinity of PLA, and improved water sensitivity and processability of TPCS. PLA and TPCS exhibited a high interfacial tension between the two phases of 7.9 mJ·m -2, indicating the formation of an incompatible, immiscible blend. SEM micrographs showed a non-homogeneous distribution of TPCS droplets in the PLA continuous phase. TEM micrographs of the blend films made by cast-film extrusion showed coalescence of the TPCS droplets in the PLA continuous phase of the blend, indicating that the compatibility between the polymer pair needs to be improved. A response surface methodology (RSM) design was used to analyze the effects of maleic anhydride (MA) and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (Luperox or L101) contents, and TSE screw speed on the degree of grafted MA and number average molecular weight (Mn) of functionalized PLA (PLA-g-MA), a reactive compatibilizer. PLA-g- MA made by reactive extrusion had an array of colors depending on the content of L101 and MA used. New FTIR peaks suggested that MA was grafted onto the PLA backbone and oligomeric MA may occur. Increasing L101 increased the degree of grafting and decreased Mn, but the Mn of the PLA-g-MA's produced with a high amount of L101 was stable during storage. MA exhibited an optimum concentration for maximizing the degree of grafted MA, and increasing MA content retarded the reduction of Mn during processing. However, the Mn of PLA-g-MA during storage decreased more rapidly with a high content of MA. TSE screw speed had an impact on the Mn with the maximum value predicted at 20 rpm. PLA-g-MA compounds differing in Mn and/or grafted MA content were used as reactive polymers with TPCS (to produce binary blends) and as reactive compatibilizers (to produce ternary blends of PLA/TPCS/PLA-g-MA) with TPCS content of 30 wt% using a TSE. As a result of maleation, PLA-g-MA had a higher grafted MA content with a lower Mn, and higher PI. The interaction of anhydride groups from PLA-g-MA and hydroxyl groups from TPCS was found by FTIR. The reactive binary blends exhibited a change in thermal stability, decrease of Tcc, the presence of double melting peaks, and an increase of the Tgs of glycerol and starch. The higher the grafted MA content and/or the higher Mn of the PLA- g-MA used, the better were the distribution and smaller the TPCS domains obtained in the blends. The highest elongation at break was achieved when 30 wt% TPCS was blended with 70 wt% of PLA having 0.1 wt% of grafted MA and Mn of PLA-g-MA with a 45 kDa. Finally, the optimum PLA-g-MA was determined by using the results from PLA-g-MA RSM design and the reactive blending.

Effect of polymer type on characterization and filtration performances of multi-walled carbon nanotubes (MWCNT)-COOH-based polymeric mixed matrix membranes.

PubMed

Sengur-Tasdemir, Reyhan; Mokkapati, Venkata R S S; Koseoglu-Imer, Derya Y; Koyuncu, Ismail

2018-05-01

Multi-walled carbon nanotubes (MWCNTs) can be used for the fabrication of mixed matrix polymeric membranes that can enhance filtration perfomances of the membranes by modifying membrane surface properties. In this study, detailed characterization and filtration performances of MWCNTs functionalized with COOH group, blended into polymeric flat-sheet membranes were investigated using different polymer types. Morphological characterization was carried out using atomic force microscopy, scanning electron microscopy and contact angle measurements. For filtration performance tests, protein, dextran, E. coli suspension, Xanthan Gum and real activated sludge solutions were used. Experimental data and analyses revealed that Polyethersulfone (PES) + MWCNT-COOH mixed matrix membranes have superior performance abilities compared to other tested membranes.

Influence of Miscibility Phenomenon on Crystalline Polymorph Transition in Poly(Vinylidene Fluoride)/Acrylic Rubber/Clay Nanocomposite Hybrid

PubMed Central

Abolhasani, Mohammad Mahdi; Naebe, Minoo; Jalali-Arani, Azam; Guo, Qipeng

2014-01-01

In this paper, intercalation of nanoclay in the miscible polymer blend of poly(vinylidene fluoride) (PVDF) and acrylic rubber(ACM) was studied. X-ray diffraction was used to investigate the formation of nanoscale polymer blend/clay hybrid. Infrared spectroscopy and X-ray analysis revealed the coexistence of β and γ crystalline forms in PVDF/Clay nanocomposite while α crystalline form was found to be dominant in PVDF/ACM/Clay miscible hybrids. Flory-Huggins interaction parameter (B) was used to further explain the miscibility phenomenon observed. The B parameter was determined by combining the melting point depression and the binary interaction model. The estimated B values for the ternary PVDF/ACM/Clay and PVDF/ACM pairs were all negative, showing both proper intercalation of the polymer melt into the nanoclay galleries and the good miscibility of PVDF and ACM blend. The B value for the PVDF/ACM blend was almost the same as that measured for the PVDF/ACM/Clay hybrid, suggesting that PVDF chains in nanocomposite hybrids interact with ACM chains and that nanoclay in hybrid systems is wrapped by ACM molecules. PMID:24551141

A high-throughput media design approach for high performance mammalian fed-batch cultures

PubMed Central

Rouiller, Yolande; Périlleux, Arnaud; Collet, Natacha; Jordan, Martin; Stettler, Matthieu; Broly, Hervé

2013-01-01

An innovative high-throughput medium development method based on media blending was successfully used to improve the performance of a Chinese hamster ovary fed-batch medium in shaking 96-deepwell plates. Starting from a proprietary chemically-defined medium, 16 formulations testing 43 of 47 components at 3 different levels were designed. Media blending was performed following a custom-made mixture design of experiments considering binary blends, resulting in 376 different blends that were tested during both cell expansion and fed-batch production phases in one single experiment. Three approaches were chosen to provide the best output of the large amount of data obtained. A simple ranking of conditions was first used as a quick approach to select new formulations with promising features. Then, prediction of the best mixes was done to maximize both growth and titer using the Design Expert software. Finally, a multivariate analysis enabled identification of individual potential critical components for further optimization. Applying this high-throughput method on a fed-batch, rather than on a simple batch, process opens new perspectives for medium and feed development that enables identification of an optimized process in a short time frame. PMID:23563583

Development of cookies made with cocoyam, fermented sorghum and germinated pigeon pea flour blends using response surface methodology.

PubMed

Okpala, Laura C; Okoli, Eric C

2014-10-01

Cookies were produced from blends of cocoyam, fermented sorghum and germinated pigeon pea flours. The study was carried out to evaluate the effects of varying the proportions of these components on the sensory and protein quality of the cookies. The sensory attributes studied were colour, taste, texture, crispness and general acceptability while the protein quality indices were biological value (BV) and net protein utilization (NPU). Mixture response surface methodology was used to model the sensory and protein quality with single, binary and ternary combinations of germinated pigeon pea, fermented sorghum and cocoyam flours. Results showed that BV and NPU of most of the cookies were above minimum acceptable levels. With the exception of cookies containing high levels of pigeon pea flour, cookies had acceptable sensory scores. Increase in pigeon pea flour resulted in increase in the BV and NPU. Regression equations suggested that the ternary blends produced the highest increase in all the sensory attributes (with the exception of colour).

The short circuit current improvement in P3HT:PCBM based polymer solar cell by introducing PSBTBT as additional electron donor.

PubMed

Sun, Lu; Shen, Liang; Mengd, Fanxu; Xu, Peng; Guo, Wenbin; Ruan, Shengping

2014-05-01

Here we demonstrate the influence of electron-donating polymer addition on the performance of poly(3-hexylthiophene) (P3HT):1 -(3-methoxycarbonyl)-propyl-1-phenyl-(6,6) C61 (PCBM) solar cells. Poly[(4,42-bis(2-ethylhexyl) dithieno [3,2-b:22,32-d] silole)-2,6-diylalt-(2,1,3-benzothiadiazole)-4,7-diyl] (PSBTBT) was chosen as the electron-donating polymer to improve the short circuit current (J(sc)) due to its distinct absorption in the near-IR range and similar HOMO level with that of P3HT. In the study, we found that J(sc) was improved for ternary blend (P3HT:PSBTBT:PCBM) solar cells. The dependence of device performance was investigated. J(sc) got decreased with increasing the ratio of PSBTBT. Result showed that J(sc) of ternary blend solar cells was improved greatly after thermal annealing at 150 degrees C, close to that of the binary blend (PSBTBT:PCBM) solar cells.

DIFFUSION MEASUREMENTS DURING PERVAPORATION THROUGH A ZEOLITE MEMBRANE

EPA Science Inventory

An isotopic-transient technique was used to directly measure diffusion times of H2O, methanol, ethanol, 2-propanol, and acetone in pure and binary mixture feeds transporting through a zeolite membrane under steady-state pervaporation conditions. Diffusivities can be determ...

Equilibrating high-molecular-weight symmetric and miscible polymer blends with hierarchical back-mapping.

PubMed

Ohkuma, Takahiro; Kremer, Kurt; Daoulas, Kostas

2018-05-02

Understanding properties of polymer alloys with computer simulations frequently requires equilibration of samples comprised of microscopically described long molecules. We present the extension of an efficient hierarchical backmapping strategy, initially developed for homopolymer melts, to equilibrate high-molecular-weight binary blends. These mixtures present significant interest for practical applications and fundamental polymer physics. In our approach, the blend is coarse-grained into models representing polymers as chains of soft blobs. Each blob stands for a subchain with N b microscopic monomers. A hierarchy of blob-based models with different resolution is obtained by varying N b . First the model with the largest N b is used to obtain an equilibrated blend. This configuration is sequentially fine-grained, reinserting at each step the degrees of freedom of the next in the hierarchy blob-based model. Once the blob-based description is sufficiently detailed, the microscopic monomers are reinserted. The hard excluded volume is recovered through a push-off procedure and the sample is re-equilibrated with molecular dynamics (MD), requiring relaxation on the order of the entanglement time. For the initial method development we focus on miscible blends described on microscopic level through a generic bead-spring model, which reproduces hard excluded volume, strong covalent bonds, and realistic liquid density. The blended homopolymers are symmetric with respect to molecular architecture and liquid structure. To parameterize the blob-based models and validate equilibration of backmapped samples, we obtain reference data from independent hybrid simulations combining MD and identity exchange Monte Carlo moves, taking advantage of the symmetry of the blends. The potential of the backmapping strategy is demonstrated by equilibrating blend samples with different degree of miscibility, containing 500 chains with 1000 monomers each. Equilibration is verified by comparing chain conformations and liquid structure in backmapped blends with the reference data. Possible directions for further methodological developments are discussed.

Equilibrating high-molecular-weight symmetric and miscible polymer blends with hierarchical back-mapping

NASA Astrophysics Data System (ADS)

Ohkuma, Takahiro; Kremer, Kurt; Daoulas, Kostas

2018-05-01

Understanding properties of polymer alloys with computer simulations frequently requires equilibration of samples comprised of microscopically described long molecules. We present the extension of an efficient hierarchical backmapping strategy, initially developed for homopolymer melts, to equilibrate high-molecular-weight binary blends. These mixtures present significant interest for practical applications and fundamental polymer physics. In our approach, the blend is coarse-grained into models representing polymers as chains of soft blobs. Each blob stands for a subchain with N b microscopic monomers. A hierarchy of blob-based models with different resolution is obtained by varying N b. First the model with the largest N b is used to obtain an equilibrated blend. This configuration is sequentially fine-grained, reinserting at each step the degrees of freedom of the next in the hierarchy blob-based model. Once the blob-based description is sufficiently detailed, the microscopic monomers are reinserted. The hard excluded volume is recovered through a push-off procedure and the sample is re-equilibrated with molecular dynamics (MD), requiring relaxation on the order of the entanglement time. For the initial method development we focus on miscible blends described on microscopic level through a generic bead-spring model, which reproduces hard excluded volume, strong covalent bonds, and realistic liquid density. The blended homopolymers are symmetric with respect to molecular architecture and liquid structure. To parameterize the blob-based models and validate equilibration of backmapped samples, we obtain reference data from independent hybrid simulations combining MD and identity exchange Monte Carlo moves, taking advantage of the symmetry of the blends. The potential of the backmapping strategy is demonstrated by equilibrating blend samples with different degree of miscibility, containing 500 chains with 1000 monomers each. Equilibration is verified by comparing chain conformations and liquid structure in backmapped blends with the reference data. Possible directions for further methodological developments are discussed.

Optimisation of cosolvent concentration for topical drug delivery III--influence of lipophilic vehicles on ibuprofen permeation.

PubMed

Watkinson, R M; Guy, R H; Oliveira, G; Hadgraft, J; Lane, M E

2011-01-01

Previously, we have reported the effects of water, ethanol, propylene glycol and various binary and ternary mixtures of these solvents on the permeation of ibuprofen in model membranes and in skin. The present study investigates the influence of lipophilic vehicles on the transport of ibuprofen in silicone membrane and in human skin. The permeation of ibuprofen was measured from mineral oil (MO), Miglyol® 812 (MG) and binary mixtures of MO and MG. The solubility of ibuprofen was 5-fold higher in MG than in MO, however, the permeation of ibuprofen from the pure vehicles and combinations of both was comparable in silicone membrane. Additionally, there were no significant differences in skin permeation for MO and MG vehicles. When the permeation of various hydrophilic and lipophilic vehicles is considered, a trend between flux values for the model membrane and skin is evident (r(2) = 0.71). The findings suggest that silicone membrane may provide information on qualitative trends in skin permeation for vehicles of diverse solubility and partition characteristics. Copyright © 2010 S. Karger AG, Basel.

Preparation of proton conducting membranes containing bifunctional titania nanoparticles

NASA Astrophysics Data System (ADS)

Aslan, Ayşe; Bozkurt, Ayhan

2013-07-01

Throughout this work, the synthesis and characterization of novel proton conducting nanocomposite membranes including binary and ternary mixtures of sulfated nano-titania (TS), poly(vinyl alcohol) (PVA), and nitrilotri(methyl phosphonic acid) (NMPA) are discussed. The materials were produced by means of two different approaches where in the first, PVA and TS (10-15 nm) were admixed to form a binary system. The second method was the ternary nanocomposite membranes including PVA/TS/NMPA that were prepared at several compositions to get PVA-TS-(NMPA) x . The interaction of functional nano particles and NMPA in the host matrix was explored by FT-IR spectroscopy. The homogeneous distribution of bifunctional nanoparticles in the membrane was confirmed by SEM micrographs. The spectroscopic measurements and water/methanol uptake studies suggested a complexation between PVA and NMPA, which inhibited the leaching of the latter. The thermogravimetry analysis results verified that the presence of TS in the composite membranes suppressed the formation of phosphonic acid anhydrides up to 150 °C. The maximum proton conductivity has been measured for PVA-TS-(NMPA)3 as 0.003 S cm-1 at 150 °C.

Dietary mixtures of sodium bicarbonate, sodium chloride, and potassium chloride: effects on lactational performance, acid-base status, and mineral metabolism of Holstein cows.

PubMed

Sanchez, W K; Beede, D K; Cornell, J A

1997-06-01

The objective of this study was to determine lactational, blood mineral, and blood acid-base responses to dietary mixtures of NaHCO3, NaCl, and KCl and dietary cation-anion difference by lactating diary cows. Three 100:0:0 (primary) blends, three 50:50:0 (binary) blends, and one 33:33:33 (tertiary) blend of NaHCO3, NaCl, and KCl, respectively, were formulated to replace 1% of the dry matter in a diet based on corn silage. Seven treatments were defined according to a simplex-centroid mixtures design using a partially balanced incomplete block arrangement. An eighth treatment served as a control and contained 1% SiO2 instead of the mineral blends. Dietary cation-anion difference ranged from +25 to +40 meq of (Na + K - Cl)/100 g of dietary dry matter. Diets were fed for three consecutive 28-d periods during summer to 36 midlactation cows. Cows that were fed the tertiary mixture had lower milk protein percentage, whole blood bicarbonate, and plasma K than did cows fed the other blends. With the exception of milk protein percentage and body weight gain, none of the mixtures had a significant impact on lactational performance. The lack of differences could have been due to the narrow range in the dietary cation-anion difference studied.

Antibacterial potential assessment of jasmine essential oil against e. Coli.

PubMed

Rath, C C; Devi, S; Dash, S K; Mishra, R K

2008-01-01

The antibacterial activity of Jasmine (Jasminum sambac L.) flower hydro steam distilled essential oil, synthetic blends and six major individual components was assessed against Escherichia coli (MTCC-443) strain. The activity was bactericidal. Minimum inhibitory concentration was determined by tube dilution technique, and the Minimum inhibitory concentration ranged between 1.9-31.25 mul/ml. Phenolcoefficient of the oil, synthetic blends and components varied between 0.6-1.7. The activity of the chemicals was possibly due to the inhibition of cell membrane synthesis.

Combined binary collision and continuum mechanics model applied to focused ion beam milling of a silicon membrane

NASA Astrophysics Data System (ADS)

Hobler, Gerhard

2015-06-01

Many experiments indicate the importance of stress and stress relaxation upon ion implantation. In this paper, a model is proposed that is capable of describing ballistic effects as well as stress relaxation by viscous flow. It combines atomistic binary collision simulation with continuum mechanics. The only parameters that enter the continuum model are the bulk modulus and the radiation-induced viscosity. The shear modulus can also be considered but shows only minor effects. A boundary-fitted grid is proposed that is usable both during the binary collision simulation and for the spatial discretization of the force balance equations. As an application, the milling of a slit into an amorphous silicon membrane with a 30 keV focused Ga beam is studied, which demonstrates the relevance of the new model compared to a more heuristic approach used in previous work.

Performance of ceramic ultrafiltration membranes and fouling behavior of a dye-polysaccharide binary system.

PubMed

Zuriaga-Agustí, E; Alventosa-deLara, E; Barredo-Damas, S; Alcaina-Miranda, M I; Iborra-Clar, M I; Mendoza-Roca, J A

2014-05-01

Ultrafiltration membrane processes have become an established technology in the treatment and reuse of secondary effluents. Nevertheless, membrane fouling arises as a major obstacle in the efficient operation of these systems. In the current study, the performance of tubular ultrafiltration ceramic membranes was evaluated according to the roles exerted by membrane pore size, transmembrane pressure and feed concentration on a binary foulant system simulating textile wastewater. For that purpose, carboxymethyl cellulose sodium salt (CMC) and an azo dye were used as colloidal and organic foulants, respectively. Results showed that a larger pore size enabled more solutes to get adsorbed into the pores, producing a sharp permeate flux decline attributed to the rapid pore blockage. Besides, an increase in CMC concentration enhanced severe fouling in the case of the tighter membrane. Concerning separation efficiency, organic matter was almost completely removed with removal efficiency above 98.5%. Regarding the dye, 93% of rejection was achieved. Comparable removal efficiencies were attributed to the dynamic membrane formed by the cake layer, which governed process performance in terms of rejection and selectivity. As a result, none of the evaluated parameters showed significant influence on separation efficiency, supporting the significant role of cake layer on filtration process. Copyright © 2014 Elsevier Ltd. All rights reserved.

Membranes of Polymers of Intrinsic Microporosity (PIM-1) Modified by Poly(ethylene glycol).

PubMed

Bengtson, Gisela; Neumann, Silvio; Filiz, Volkan

2017-06-05

Until now, the leading polymer of intrinsic microporosity PIM-1 has become quite famous for its high membrane permeability for many gases in gas separation, linked, however, to a rather moderate selectivity. The combination with the hydrophilic and low permeable poly(ethylene glycol) (PEG) and poly(ethylene oxides) (PEO) should on the one hand reduce permeability, while on the other hand enhance selectivity, especially for the polar gas CO₂ by improving the hydrophilicity of the membranes. Four different paths to combine PIM-1 with PEG or poly(ethylene oxide) and poly(propylene oxide) (PPO) were studied: physically blending, quenching of polycondensation, synthesis of multiblock copolymers and synthesis of copolymers with PEO/PPO side chain. Blends and new, chemically linked polymers were successfully formed into free standing dense membranes and measured in single gas permeation of N₂, O₂, CO₂ and CH₄ by time lag method. As expected, permeability was lowered by any substantial addition of PEG/PEO/PPO regardless the manufacturing process and proportionally to the added amount. About 6 to 7 wt % of PEG/PEO/PPO added to PIM-1 halved permeability compared to PIM-1 membrane prepared under similar conditions. Consequently, selectivity from single gas measurements increased up to values of about 30 for CO₂/N₂ gas pair, a maximum of 18 for CO₂/CH₄ and 3.5 for O₂/N₂.

Durable pd-based alloy and hydrogen generation membrane thereof

DOEpatents

Benn, Raymond C.; Opalka, Susanne M.; Vanderspurt, Thomas Henry

2010-02-02

A durable Pd-based alloy is used for a H.sub.2-selective membrane in a hydrogen generator, as in the fuel processor of a fuel cell plant. The Pd-based alloy includes Cu as a binary element, and further includes "X", where "X" comprises at least one metal from group "M" that is BCC and acts to stabilize the .beta. BCC phase for stability during operating temperatures. The metal from group "M" is selected from the group consisting of Fe, Cr, Nb, Ta, V, Mo, and W, with Nb and Ta being most preferred. "X" may further comprise at least one metal from a group "N" that is non-BCC, preferably FCC, that enhances other properties of the membrane, such as ductility. The metal from group "N" is selected from the group consisting of Ag, Au, Re, Ru, Rh, Y, Ce, Ni, Ir, Pt, Co, La and In. The at. % of Pd in the binary Pd--Cu alloy ranges from about 35 at. % to about 55 at. %, and the at. % of "X" in the higher order alloy, based on said binary alloy, is in the range of about 1 at. % to about 15 at. %. The metals are selected according to a novel process.

Enhancement of antibacterial activity in nanofillers incorporated PSF/PVP membranes

NASA Astrophysics Data System (ADS)

Pramila, P.; Gopalakrishnan, N.

2018-04-01

An attempt has been made to investigate the nanofillers incorporated polysulfone (PSF) and polyvinylpyrrolidone (PVP) polymer membranes prepared by phase inversion method. Initially, the nanofillers, viz, Zinc Oxide (ZnO) nanoparticle, Graphene Oxide-Zinc Oxide (GO-ZnO) nanocomposite were synthesized and then directly incorporated into PSF/PVP blend during the preparation of membranes. The prepared membranes have been subjected to FE-SEM, AFM, BET, contact angle, tensile test and anti-bacterial studies. Significant membrane morphologies and nanoporous properties have been observed by FE-SEM and BET, respectively. It has been observed that hydrophilicity, mechanical strength and water permeability of the ZnO and GO-ZnO incorporated membranes were enhanced than bare membrane. Antibacterial activity was assessed by measuring the inhibition zones formed around the membrane by disc-diffusion method using Escherichia coli (gram-negative) as a model bacterium. Again, it has been observed that nanofillers incorporated membrane exhibits high antibacterial performance compared to bare membrane.

Fabrication of PVDF-based blend membrane with a thin hydrophilic deposition layer and a network structure supporting layer via the thermally induced phase separation followed by non-solvent induced phase separation process

NASA Astrophysics Data System (ADS)

Wu, Zhiguo; Cui, Zhenyu; Li, Tianyu; Qin, Shuhao; He, Benqiao; Han, Na; Li, Jianxin

2017-10-01

A simple strategy of thermally induced phase separation followed by non-solvent induced phase separation (TIPS-NIPS) is reported to fabricate poly (vinylidene fluoride) (PVDF)-based blend membrane. The dissolved poly (styrene-co-maleic anhydride) (SMA) in diluent prevents the crystallization of PVDF during the cooling process and deposites on the established PVDF matrix in the later extraction. Compared with traditional coating technique, this one-step TIPS-NIPS method can not only fabricate a supporting layer with an interconnected network structure even via solid-liquid phase separation of TIPS, but also form a uniform SMA skin layer approximately as thin as 200 nm via surface deposition of NIPS. Besides the better hydrophilicity, what's interesting is that the BSA rejection ratio increases from 48% to 94% with the increase of SMA, which indicates that the separation performance has improved. This strategy can be conveniently extended to the creation of firmly thin layer, surface functionalization and structure controllability of the membrane.

Effect of Binary Source Companions on the Microlensing Optical Depth Determination toward the Galactic Bulge Field

NASA Astrophysics Data System (ADS)

Han, Cheongho

2005-11-01

Currently, gravitational microlensing survey experiments toward the Galactic bulge field use two different methods of minimizing the blending effect for the accurate determination of the optical depth τ. One is measuring τ based on clump giant (CG) source stars, and the other is using ``difference image analysis'' (DIA) photometry to measure the unblended source flux variation. Despite the expectation that the two estimates should be the same assuming that blending is properly considered, the estimates based on CG stars systematically fall below the DIA results based on all events with source stars down to the detection limit. Prompted by the gap, we investigate the previously unconsidered effect of companion-associated events on τ determination. Although the image of a companion is blended with that of its primary star and thus not resolved, the event associated with the companion can be detected if the companion flux is highly magnified. Therefore, companions work effectively as source stars to microlensing, and thus the neglect of them in the source star count could result in a wrong τ estimation. By carrying out simulations based on the assumption that companions follow the same luminosity function as primary stars, we estimate that the contribution of the companion-associated events to the total event rate is ~5fbi% for current surveys and can reach up to ~6fbi% for future surveys monitoring fainter stars, where fbi is the binary frequency. Therefore, we conclude that the companion-associated events comprise a nonnegligible fraction of all events. However, their contribution to the optical depth is not large enough to explain the systematic difference between the optical depth estimates based on the two different methods.

Self-assembly of Nano-rods in Photosensitive Phase Separation

NASA Astrophysics Data System (ADS)

Liu, Ya; Kuksenok, Olga; Maresov, Egor; Balazs, Anna

2012-02-01

Computer simulations reveal how photo-induced chemical reactions in polymeric mixtures can be exploited to create long-range order in materials whose features range from the sub-micron to the nanoscale. The process is initiated by shining a spatially uniform light on a photosensitive AB binary blend, which thereby undergoes both a reversible chemical reaction and phase separation. When a well-collimated, higher intensity light is rastered over the sample, the system forms defect-free, spatially periodic structures. We now build on this approach by introducing nanorods that have a preferential affinity for one the phases in a binary mixture. By rastering over the sample with the higher intensity light, we can create ordered arrays of rods within periodically ordered materials in essentially one processing step.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pal, Suresh, E-mail: ajay-phy@rediffmail.com; Tiwari, R. K.; Gupta, D. C.

In this paper, we present the expressions relating the inter atomic force constants like as bond-stretching force constant (α in N/m) and bond-bending force constant (β in N/m) for the binary (zinc blende structure) and ternary (chalcopyrite structure) semiconductors with the product of ionic charges (PIC) and crystal ionicity (f{sub i}). Interatomic force constants of these compounds exhibit a linear relationship; when plot a graph between Interatomic force constants and the nearest neighbor distance d (Å) with crystal ionicity (f{sub i}), but fall on different straight lines according to the product of ionic charges of these compounds. A fairly goodmore » agreement has been found between the observed and calculated values of the α and β for binary and ternary tetrahedral semiconductors.« less

Method and apparatus for removing non-condensible gas from a working fluid in a binary power system

DOEpatents

Mohr, Charles M.; Mines, Gregory L.; Bloomfield, K. Kit

2002-01-01

Apparatus for removing non-condensible gas from a working fluid utilized in a thermodynamic system comprises a membrane having an upstream side operatively connected to the thermodynamic system so that the upstream side of the membrane receives a portion of the working fluid. The first membrane separates the non-condensible gas from the working fluid. A pump operatively associated with the membrane causes the portion of the working fluid to contact the membrane and to be returned to the thermodynamic system.

Relationships between surface coverage ratio and powder mechanics of binary adhesive mixtures for dry powder inhalers.

PubMed

Rudén, Jonas; Frenning, Göran; Bramer, Tobias; Thalberg, Kyrre; Alderborn, Göran

2018-04-25

The aim of this paper was to study relationships between the content of fine particles and the powder mechanics of binary adhesive mixtures and link these relationships to the blend state. Mixtures with increasing amounts of fine particles (increasing surface coverage ratios (SCR)) were prepared using Lactopress SD as carrier and micro particles of lactose as fines (2.7 µm). Indicators of unsettled bulk density, compressibility and flowability were derived and the blend state was visually examined by imaging. The powder properties studied showed relationships to the SCR characterised by stages. At low SCR, the fine particles predominantly gathered in cavities of the carriers, giving increased bulk density and unchanged or improved flow. Thereafter, increased SCR gave a deposition of particles at the enveloped carrier surface with a gradually more irregular adhesion layer leading to a reduced bulk density and a step-wise reduced flowability. The mechanics of the mixtures at a certain stage were dependent on the structure and the dynamics of the adhesion layer and transitions between the stages were controlled by the evolution of the adhesion layer. It is advisable to use techniques based on different types of flow in order to comprehensively study the mechanics of adhesive mixtures. Copyright © 2018 Elsevier B.V. All rights reserved.

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT - PHYSICAL REMOVAL OF MICROBIOLOGICAL & PARTICULATE CONTAMINANTS IN DRINKING WATER: US FILTER 3M10C MICROFILTRATION MEMBRANE SYSTEM AT CHULA VISTA, CALIFORNIA

EPA Science Inventory

Verification testing of the US Filter 3M10C membrane system was conducted over a 44-day test period at the Aqua 2000 Research Center in Chula Vista, California. The test period extended from July 24, 2002 to September 5, 2002. The source water was a blend of Colorado River and ...

Bimodal fibrous structures for tissue engineering: Fabrication, characterization and in vitro biocompatibility.

PubMed

Tiwari, Arjun Prasad; Joshi, Mahesh Kumar; Kim, Jeong In; Unnithan, Afeesh Rajan; Lee, Joshua; Park, Chan Hee; Kim, Cheol Sang

2016-08-15

We report for the first time a polycaprolactone-human serum albumin (PCL-HSA) membrane with bimodal structures comprised of spider-web-like nano-nets and conventional fibers via facile electro-spinning/netting (ESN) technique. Such unique controllable morphology was developed by electrospinning the blend solution of PCL (8wt% in HFIP 1,1,1,3,3,3,-Hexafluoro-2-propanol) and HSA (10wt% deionized water). The phase separation during electrospinning caused the formation of bimodal structure. Various processing factors such as applied voltage, feeding rate, and distance between nozzle tip and collector were found responsible for the formation and distribution of the nano-nets throughout the nanofibrous mesh. Field emission electron microscopy (FE-SEM) confirmed that the nano-nets were composed of interlinked nanowires with an ultrathin diameter (10-30nm). When compared with a pure PCL membrane, the membrane containing nano-nets was shown to have better support for cellular activities as determined by cell viability and attachment assays. These results revealed that the blending of albumin, a hydrophilic biomolecule, with PCL, a hydrophobic polymer, proves to be an outstanding approach to developing membranes with controlled spider-web-like nano-nets for tissue engineering. Copyright © 2016 Elsevier Inc. All rights reserved.

Elaboration, characterization and application of polysulfone and polyacrylic acid blends as ultrafiltration membranes for removal of some heavy metals from water.

PubMed

Mbareck, Chamekh; Nguyen, Quang Trong; Alaoui, Ouafa Tahiri; Barillier, Daniel

2009-11-15

Polysulfone (PSf)/polyacrylic acid ultrafiltration (PSf/PAA) membranes were prepared from a polymer blend in dimethylformamide by coagulation in water according to the wet phase inversion method. Immobilization of water-soluble PAA within the non-soluble PSf matrix was proven by the increase of ion exchange capacity and the intensity of the carboxyl groups' peak with the increase of PAA content as shown by Fourier transform infrared spectra. These results lead to consider that PSf and PAA form a semi-interpenetrating polymer networks. The obtained membranes showed a decrease of mean surface-pore sizes, the overall porosity and the hydraulic permeability with the increase in PAA content. Such results were imputed to the morphologic modifications of PSf film with the immobilization of increasing PAA amount. PSf/PAA membranes showed high lead, cadmium and chromium rejection which reaches 100% at pH superior to 5.7 and a low rejection at low pH. Moreover, the heavy metal rejection decreases with feed solution concentration and applied pressure increases. These behaviors were attributed to the role of carboxylic groups in ion exchange or complexation. As a matter of fact, the strong lead ion-PAA interactions were revealed by the scanning electron microscopy with energy dispersive X-rays (SEM-EDX).

Selective Permeating Properties of Butanol and Water through Polystyrene- b-polydimethylsiloxane- b-polystyrene Pervaporation Membranes

NASA Astrophysics Data System (ADS)

Shin, Chaeyoung; Baer, Zachary; Chen, X. Chelsea; Ozcam, A. Evren; Clark, Douglas; Balsara, Nitash

2015-03-01

Polystyrene- b-polydimethylsiloxane- b-polystyrene (SDS) membranes have been studied in butanol-water binary pervaporation experiments and pervaporation experiments integrated with viable fermentation broths. Polydimethylsiloxane has been widely known to be a suitable material for separating organic chemicals from aqueous solutions, and it thus provides a continuous matrix phase in SDS membranes for permeation of small molecules. The polystyrene block provides mechanical stability to maintain the membrane structure in the pervaporation membranes. We take advantage of these features to fabricate a thin and butanol-selective SDS membrane for in situ product removal in fermentation.

Proton-conducting ionic liquid-based Proton Exchange Membrane Fuel Cell membranes: The key role of ionomer-ionic liquid interaction

NASA Astrophysics Data System (ADS)

Martinez, Mathieu; Molmeret, Yannick; Cointeaux, Laure; Iojoiu, Cristina; Leprêtre, Jean-Claude; El Kissi, Nadia; Judeinstein, Patrick; Sanchez, Jean-Yves

The paper deals with the synthesis and characterisation of proton-conducting ionic liquids (PCILs) and their polymer electrolytes obtained by blending modified Nafion membranes with different concentrations of PCILs. The PCILs are obtained by the neutralization of triethylamine with different organic acids. The first part of the paper studies the influence of acidity and acid structure on PCIL thermal and electrochemical performance, while the second part examines membrane conductivity and reveals it to depend more on PCIL structure than on its intrinsic conductivity. At 130 °C, conductivities exceeding 10 mS cm -1 were obtained in fully anhydrous conditions.

SPEEK/PVDF/PES Composite as Alternative Proton Exchange Membrane for Vanadium Redox Flow Batteries

NASA Astrophysics Data System (ADS)

Fu, Zhimin; Liu, Jinying; Liu, Qifeng

2016-01-01

A membrane consisting of a blend of sulfonated poly(ether ether ketone) (SPEEK), poly(vinylidene fluoride) (PVDF), and poly(ether sulfone) (PES) has been fabricated and used as an ion exchange membrane for application in vanadium redox flow batteries (VRBs). The vanadium ion permeability of the SPEEK/PVDF/PES membrane was one order of magnitude lower than that of Nafion 117 membrane. The low-cost composite membrane exhibited better performance than Nafion 117 membrane at the same operating condition. A VRB single cell with SPEEK/PVDF/PES membrane showed significantly lower capacity loss, higher coulombic efficiency (>95%), and higher energy efficiency (>82%) compared with Nafion 117 membrane. In the self-discharge test, the duration of the cell with the SPEEK/PVDF/PES membrane was nearly two times longer than that with Nafion 117 membrane. Considering these good properties and its low cost, SPEEK/PVDF/PES membrane is expected to have excellent commercial prospects as an ion exchange membrane for VRB systems.

A promising azeotrope-like mosquito repellent blend.

PubMed

Izadi, Homa; Focke, Walter W; Asaadi, Erfan; Maharaj, Rajendra; Pretorius, Jannie; Loots, Mattheüs Theodor

2017-08-31

Topical repellents play a key role in reducing the outdoor transmission of mosquito-borne diseases by reducing human-vector contact. Excellent repellents are available, but there is always room for improvement. This article reports on a particularly effective binary repellent blend of ethyl butylacetylaminopropionate and nonanoic acid. A composition containing 25 mol% of the acid exhibits negative pseudo-azeotrope behaviour at 50 °C, meaning that the liquid vapour pressure is lower than that of the parent compounds and evaporation occurs without a change in the liquid composition. In tests performed using the South African Medical Research Council's cup-on-arm procedure, this mixture provided better protection for a longer time than the "gold standard of mosquito repellents", namely N,N-diethyl-m-toluamide, commonly known as DEET.

Exploring the Photovoltaic Performance of All-Inorganic Ag2PbI4/PbI2 Blends.

PubMed

Frolova, Lyubov A; Anokhin, Denis V; Piryazev, Alexey A; Luchkin, Sergey Yu; Dremova, Nadezhda N; Troshin, Pavel A

2017-04-06

We present an all-inorganic photoactive material composed of Ag 2 PbI 4 and PbI 2 , which shows unexpectedly good photovoltaic performance in planar junction solar cells delivering external quantum efficiencies of ∼60% and light power conversion efficiencies of ∼3.9%. The revealed characteristics are among the best reported to date for metal halides with nonperovskite crystal structure. Most importantly, the obtained results suggest a possibility of reaching high photovoltaic efficiencies for binary and, probably, also ternary blends of different inorganic semiconductor materials. This approach, resembling the bulk heterojunction concept guiding the development of organic photovoltaics for two decades, opens wide opportunities for rational design of novel inorganic and hybrid materials for efficient and sustainable photovoltaic technologies.

Size segregation of component coals during pulverization of high volatile/low volatile blends

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, A.; Orban, P.C.

1995-12-31

Samples of single high volatile (hvb) and low volatile (lvb) coals and binary blends in proportions ranging from 75%hvb/25%lvb to 25%hvb/75%lvb were pulverized in a Raymond 271 bowl mill and then screened into different size fractions. The ranks of two of the feed coals were sufficiently different that individual particles could be distinguished microscopically. This enabled the proportions of each feed coal in the various blend size fractions to be determined. The difference in rank and therefore grindability of the components (Hardgrove indices of 99 versus 50) was such that significant segregation resulted. For example, the 25%hvb/75%lvb blend, upon grinding,more » produced a +50 mesh (300 {micro}m) fraction with 30% lvb coal, and a {minus}325 mesh (45 {micro}m) fraction with 84% lvb coal. The effect of this segregation according to size was a notable progressive decrease in volatility towards the finer fractions, consistent with an increase in the proportion of lvb particles; differences in volatile matter (d.b.) between coarsest and finest fractions of up to 6.9% were encountered. Although most of the segregation is attributable to rank difference between the component coals, part appears to be due to the lower grindability of liptinite-rich lithotypes in the hvb coal.« less

Preparation and blood compatibility of polysiloxane/liquid-crystal composite membranes.

PubMed

Li, L; Tu, M; Mou, S; Zhou, C

2001-10-01

Polysiloxane/liquid crystal composite membrane was first suggested to be used as biomaterials. In this work, the polydimethyl-methylhydrosiloxane and polydimethyl-methylethylenesilosiane, as a substrate, were blended with cholesteryl oleyl carbonate (COC) in tetrahydrofuran, and then crosslinked into membranes on glass plates by means of the platinum catalyst at 110 degrees C for 20 min. The effects of the liquid-crystal content in composite membranes on the formation of liquid-crystal phase were verified by the observation of optical polarization microscopy. The relationship between the morphology of the composite membranes and blood compatibility was identified by the dynamic blood-clotting tests, haemolysis ratio measurement, platelet adhesion and SEM observation. The results show that the blood-compatibility of composite membranes with the concentration of liquid crystal 20, 30% (wt) is more excellent than that of other composite membranes.

Novel Pendant Benzene Disulfonic Acid Blended SPPO Membranes for Alkali Recovery: Fabrication and Properties.

PubMed

Mondal, Abhishek N; Dai, Chunhua; Pan, Jiefeng; Zheng, Chunlei; Hossain, Md Masem; Khan, Muhammad Imran; Wu, Liang; Xu, Tongwen

2015-07-29

To reconcile the trade-off between separation performance and availability of desired material for cation exchange membranes (CEMs), we designed and successfully prepared a novel sulfonated aromatic backbone-based cation exchange precursor named sodium 4,4'-(((((3,3'-disulfo-[1,1'-biphenyl]-4,4'-diyl)bis(oxy)) bis(4,1-phenylene))bis(azanediyl))bis(methylene))bis(benzene-1,3-disulfonate) [DSBPB] from 4,4'-bis(4-aminophenoxy)-[1,1'-biphenyl]-3,3'-disulfonic acid [BAPBDS] by a three-step procedure that included sulfonation, Michael condensation followed by reduction. Prepared DSBPB was used to blend with sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) to get CEMs for alkali recovery via diffusion dialysis. Physiochemical properties and electrochemical performance of prepared membranes can be tuned by varying the dosage of DSBPB. All the thermo-mechanical properties like DMA and TGA were investigated along with water uptake (WR), ion exchange capacity (IEC), dimensional stability, etc. The effect of DSBPB was discussed in brief in connection with alkali recovery and ion conducting channels. The SPPO/DSBPB membranes possess both high water uptake as well as ion exchange capacity with high thermo-mechanical stability. At 25 °C the dialysis coefficients (UOH) appeared to be in the range of 0.0048-0.00814 m/h, whereas the separation factor (S) ranged from 12.61 to 36.88 when the membranes were tested for base recovery in Na2WO4/NaOH waste solution. Prepared membranes showed much improved DD performances compared to traditional SPPO membrane and possess the potentiality to be a promising candidate for alkali recovery via diffusion dialysis.

Orbital Solution for the Spectroscopic Binary in the GW Ori Hierarchical Triple

NASA Astrophysics Data System (ADS)

Prato, L.; Ruíz-Rodríguez, Dary; Wasserman, L. H.

2018-01-01

We present the first double-lined orbital solution for the close binary in the GW Ori triple system. Using 12 epochs of infrared spectroscopy, we detected the lines of both stars in the inner pair, previously known as single-lined only. Our preliminary infrared orbital solution has an eccentricity of e = 0.21 ± 0.10, a period of P = 241.15 ± 0.72 days, and a mass ratio of q = 0.66 ± 0.13. We find a larger semi-amplitude for the primary star, K1 = 6.57 ± 1.00 km s‑1, with an infrared-only solution compared to K1 = 4.41 ± 0.33 km s‑1 with optical data from the literature, likely the result of line blending and veiling in the optical. The component spectral types correspond to G3 and K0 stars, with v\\sin i values of 43 km s‑1 and 50 km s‑1, respectively. We obtained a flux ratio of α = 0.58 ± 0.14 in the H-band, allowing us to estimate individual masses of 3.2 and 2.7 M ⊙ for the primary and secondary, respectively, using evolutionary tracks. The tracks also yield a coeval age of 1 Myr for both components to within 1σ. GW Ori is surrounded by a circumbinary/circumtriple disk. A tertiary component has been detected in previous studies; however, we did not detect this component in our near-infrared spectra, probably the result of its relative faintness and blending in the absorption lines of these rapidly rotating stars. With these results, GW Ori joins the small number of classical T Tauri, double-lined spectroscopic binaries.

Antibacterial Potential Assessment of Jasmine Essential Oil Against E. Coli

PubMed Central

Rath, C. C.; Devi, S.; Dash, S. K.; Mishra, R. K.

2008-01-01

The antibacterial activity of Jasmine (Jasminum sambac L.) flower hydro steam distilled essential oil, synthetic blends and six major individual components was assessed against Escherichia coli (MTCC-443) strain. The activity was bactericidal. Minimum inhibitory concentration was determined by tube dilution technique, and the Minimum inhibitory concentration ranged between 1.9-31.25 μl/ml. Phenolcoefficient of the oil, synthetic blends and components varied between 0.6-1.7. The activity of the chemicals was possibly due to the inhibition of cell membrane synthesis. PMID:20046722

Enhanced permeability and antifouling performance of cellulose acetate ultrafiltration membrane assisted by l-DOPA functionalized halloysite nanotubes.

PubMed

Mu, Keguang; Zhang, Dalun; Shao, Ziqiang; Qin, Dujian; Wang, Yalong; Wang, Shuo

2017-10-15

l-Dopa functionalized halloysite nanotubes (HNTs) were prepared by the self-polymerization of l-dopa in the weak alkaline condition. Then different contents of l-dopa coated HNTs (LPDHNTs) were blended into cellulose acetate to prepare enhanced performance ultrafiltration membranes via the phase inversion method. The HNTs and LPDHNTs were characterized by FTIR, XPS, and TEM anysis. And the membranes morphologies, separation performance, antifouling performance, mechanical properties and hydrophilicity were also investigated. It was found that the composite membranes exhibited excellent antifouling performance. The pure water flux of 3.0wt% LPDHNTs/CA membrane increased from 11.4Lm -2 h -1 to 92.9Lm -2 h -1 , while the EA rejection ratio of the membrane was about 91.2%. In addition, the mechanical properties of the resultant membranes were strengthened compared with the CA ultrafiltration membrane. Copyright © 2017 Elsevier Ltd. All rights reserved.

Formulation and characterization of poly(propylacrylic acid)/poly(lactic-co-glycolic acid) blend microparticles for pH-dependent membrane disruption and cytosolic delivery.

PubMed

Fernando, Lawrence P; Lewis, Jamal S; Evans, Brian C; Duvall, Craig L; Keselowsky, Benjamin G

2018-04-01

Poly(lactic-co-glycolic acid) (PLGA) is widely used as a vehicle for delivery of pharmaceutically relevant payloads. PLGA is readily fabricated as a nano- or microparticle (MP) matrix to load both hydrophobic and hydrophilic small molecular drugs as well as biomacromolecules such as nucleic acids and proteins. However, targeting such payloads to the cell cytosol is often limited by MP entrapment and degradation within acidic endolysosomes. Poly(propylacrylic acid) (PPAA) is a polyelectrolyte polymer with the membrane disruptive capability triggered at low pH. PPAA has been previously formulated in various carrier configurations to enable cytosolic payload delivery, but requires sophisticated carrier design. Taking advantage of PPAA functionality, we have incorporated PPAA into PLGA MPs as a simple polymer mixture to enhance cytosolic delivery of PLGA-encapsulated payloads. Rhodamine loaded PLGA and PPAA/PLGA blend MPs were prepared by a modified nanoprecipitation method. Incorporation of PPAA into PLGA MPs had little to no effect on the size, shape, or loading efficiency, and evidenced no toxicity in Chinese hamster ovary epithelial cells. Notably, incorporation of PPAA into PLGA MPs enabled pH-dependent membrane disruption in a hemolysis assay, and a three-fold increased endosomal escape and cytosolic delivery in dendritic cells after 2 h of MP uptake. These results demonstrate that a simple PLGA/PPAA polymer blend is readily fabricated into composite MPs, enabling cytosolic delivery of an encapsulated payload. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1022-1033, 2018. © 2017 Wiley Periodicals, Inc.

Calibration sets selection strategy for the construction of robust PLS models for prediction of biodiesel/diesel blends physico-chemical properties using NIR spectroscopy

NASA Astrophysics Data System (ADS)

Palou, Anna; Miró, Aira; Blanco, Marcelo; Larraz, Rafael; Gómez, José Francisco; Martínez, Teresa; González, Josep Maria; Alcalà, Manel

2017-06-01

Even when the feasibility of using near infrared (NIR) spectroscopy combined with partial least squares (PLS) regression for prediction of physico-chemical properties of biodiesel/diesel blends has been widely demonstrated, inclusion in the calibration sets of the whole variability of diesel samples from diverse production origins still remains as an important challenge when constructing the models. This work presents a useful strategy for the systematic selection of calibration sets of samples of biodiesel/diesel blends from diverse origins, based on a binary code, principal components analysis (PCA) and the Kennard-Stones algorithm. Results show that using this methodology the models can keep their robustness over time. PLS calculations have been done using a specialized chemometric software as well as the software of the NIR instrument installed in plant, and both produced RMSEP under reproducibility values of the reference methods. The models have been proved for on-line simultaneous determination of seven properties: density, cetane index, fatty acid methyl esters (FAME) content, cloud point, boiling point at 95% of recovery, flash point and sulphur.

Influence of Polyphosphoric Acid on the Consistency and Composition of Formulated Bitumen: Standard Characterization and NMR Insights

PubMed Central

Varanda, Catarina; Ribeiro, Jorge

2016-01-01

Over the recent years, bitumen modification with polymers, acids, or mineral fillers has gained relevance to adjust its performance properties. This work reports the use of polyphosphoric acid (PPA) for the modification of formulated bitumen. With this objective, an in-depth literature review on PPA modification was firstly performed. Subsequently, five individual refinery components were selected for the preparation of bitumen blends, namely, asphaltic residue, vacuum residue, and three lube oils extracts. Seven binary/ternary bitumen blends were prepared and then treated with PPA. Afterwards, the five components and the unmodified and PPA-modified bitumen were characterized by standard methods (penetration, softening point, and penetration index), SARA analysis, elemental analysis, and 31P and 1H nuclear magnetic resonance (NMR) spectroscopy. The results evidenced higher asphaltenes and lower saturates/resins contents in PPA-modified bitumen. The NMR data suggest that the paraffinic chains became longer, the content of condensed aromatics increased, more substituted aromatic structures appeared, and α-hydrogen in aromatic structures diminished. These findings disclosed the improved consistency and oxidation stability of PPA-modified bitumen blends. PMID:27579214

Peripheral Coding of Sex Pheromone Blends with Reverse Ratios in Two Helicoverpa Species

PubMed Central

Huang, Ling-Qiao; Yan, Fu-Shun; Wang, Chen-Zhu

2013-01-01

The relative proportions of components in a pheromone blend play a major role in sexual recognition in moths. Two sympatric species, Helicoverpa armigera and Helicoverpa assulta, use (Z)-11-hexadecenal (Z11–16: Ald) and (Z)-9-hexadecenal (Z9–16: Ald) as essential sex pheromone components but in very different ratios, 97∶3 and 7∶93 respectively. Using wind tunnel tests, single sensillum recording and in vivo calcium imaging, we comparatively studied behavioral responses and physiological activities at the level of antennal sensilla and antennal lobe (AL) in males of the two species to blends of the two pheromone components in different ratios (100∶0, 97∶3, 50∶50, 7∶93, 0∶100). Z11–16: Ald and Z9–16: Ald were recognized by two populations of olfactory sensory neurons (OSNs) in different trichoid sensilla on antennae of both species. The ratios of OSNs responding to Z11–16:Ald and Z9–16:Ald OSNs were 100∶28.9 and 21.9∶100 in H. armigera and H. assulta, respectively. The Z11–16:Ald OSNs in H. armigera exhibited higher sensitivity and efficacy than those in H. assulta, while the Z9–16:Ald OSNs in H. armigera had the same sensitivity but lower efficacy than those in H. assulta. At the dosage of 10 µg, Z11–16: Ald and Z9–16: Ald evoked calcium activity in 8.5% and 3.0% of the AL surface in H. armigera, while 5.4% and 8.6% of AL in H. assulta, respectively. The calcium activities in the AL reflected the peripheral input signals of the binary pheromone mixtures and correlated with the behavioral output. These results demonstrate that the binary pheromone blends were precisely coded by the firing frequency of individual OSNs tuned to Z11–16: Ald or Z9–16: Ald, as well as their population sizes. Such information was then accurately reported to ALs of H. armigera and H. assulta, eventually producing different behaviors. PMID:23894593

Visualization and analysis of lipopolysaccharide distribution in binary phospholipid bilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henning, Maria Florencia; Sanchez, Susana; Bakas, Laura, E-mail: lbakas@biol.unlp.edu.ar

2009-05-22

Lipopolysaccharide (LPS) is an endotoxin released from the outer membrane of Gram-negative bacteria during infections. It have been reported that LPS may play a role in the outer membrane of bacteria similar to that of cholesterol in eukaryotic plasma membranes. In this article we compare the effect of introducing LPS or cholesterol in liposomes made of dipalmitoylphosphatidylcholine/dioleoylphosphatidylcholine on the solubilization process by Triton X-100. The results show that liposomes containing LPS or cholesterol are more resistant to solubilization by Triton X-100 than the binary phospholipid mixtures at 4 {sup o}C. The LPS distribution was analyzed on GUVs of DPPC:DOPC usingmore » FITC-LPS. Solid and liquid-crystalline domains were visualized labeling the GUVs with LAURDAN and GP images were acquired using a two-photon microscope. The images show a selective distribution of LPS in gel domains. Our results support the hypothesis that LPS could aggregate and concentrate selectively in biological membranes providing a mechanism to bring together several components of the LPS-sensing machinery.« less

Nanofiber-net-binary structured membranes for highly sensitive detection of trace HCl gas

NASA Astrophysics Data System (ADS)

Wang, Xianfeng; Wang, Jialin; Si, Yang; Ding, Bin; Yu, Jianyong; Sun, Gang; Luo, Wenjing; Zheng, Gang

2012-11-01

This work describes the detection of trace hydrogen chloride (HCl) gas through analyses of the resonance frequency signal from quartz crystal microbalance (QCM) sensors coated with polyaniline (PANI) functionalized polyamide 6 (PA 6) (PANI-PA 6) nanofiber-net-binary (NNB) structured membranes. The PA 6 NNB substrate comprising nanofibers and spider-web-like nano-nets fabricated by a versatile electro-spinning/netting (ESN) process offered an ideal interface for the uniform PANI functionalization and enhanced sensing performance. Benefiting from the large specific surface area, high porosity, and strong adhesive force to the QCM electrode of the PANI-PA 6 NNB membranes, the developed HCl-selective sensors exhibited a rapid response, good reproducibility and stability, and low detection limit (7 ppb) at room temperature. Additionally, the PANI-PA 6 NNB sensing membranes presented visible color changes upon cycled exposure to HCl and ammonia, suggesting their potential application in the development of colorimetric sensors. The PANI-PA 6 NNB coated QCM sensors are considered to be a promising candidate for trace HCl gas detection in practical applications.

Single Molecule Measurements of Interaction Free Energies Between the Proteins Within Binary and Ternary SNARE Complexes

PubMed Central

Liu, W.; Montana, Vedrana; Parpura, Vladimir; Mohideen, U.

2010-01-01

We use an Atomic Force Microscope based single molecule measurements to evaluate the activation free energy in the interaction of SNARE proteins syntaxin 1A, SNAP25B and synaptobrevin 2 which regulate intracellular fusion of vesicles with target membranes. The dissociation rate of the binary syntaxin-synaptobrevin and the ternary syntaxin-SNAP25B-synaptobrevin complex was measured from the rupture force distribution as a function of the rate of applied force. The temperature dependence of the spontaneous dissociation rate was used to obtain the activation energy to the transition state of 19.8 ± 3.5 kcal/mol = 33 ± 6 kBT and 25.7 ± 3.0 kcal/mol = 43 ± 5 kBT for the binary and ternary complex, respectively. They are consistent with those measured previously for the ternary complex in lipid membranes and are of order expected for bilayer fusion and pore formation. The ΔG was 12.4–16.6 kcal/mol = 21–28 kBT and 13.8–18.0 kcal/mol = 23–30 kBT for the binary and ternary complex, respectively. The ternary complex was more stable by 1.4 kcal/mol = 2.3 kBT, consistent with the spontaneous dissociation rates. The higher adhesion energies and smaller molecular extensions measured with SNAP25B point to its possible unique and important physiological role in tethering/docking the vesicle in closer proximity to the plasma membrane and increasing the probability for fusion completion. PMID:20107522

The structures of the crystalline phase and columnar mesophase of rhodium (II) heptanoate and of its binary mixture with copper (II) heptanoate probed by EXAFS

NASA Astrophysics Data System (ADS)

Inb-Elhaj, M.; Guillon, D.; Skoulios, A.; Maldivi, P.; Giroud-Godquin, A. M.; Marchon, J.-C.

1992-12-01

EXAFS was used to investigate the local structure of the polar spines of rhodium (II) soaps in the columnar liquid crystalline state. It was also used to ascertain the degree of blending of the cores in binary mixtures of rhodium (II) and copper (II) soaps. For the pure rhodium soaps, the columns are shown to result from the stacking of binuclear metal-metal bonded dirhodium tetracarboxylate units bonded to one another by apical ligation of the metal atom of each complex with one of the oxygen atoms of the adjacent molecule. Mixtures of rhodium (II) and copper (II) soaps give a hexagonal columnar mesophase in which pure rhodium and pure copper columns are randomly distributed.

Development of a custom on-line ultrasonic vapour analyzer and flow meter for the ATLAS inner detector, with application to Cherenkov and gaseous charged particle detectors

NASA Astrophysics Data System (ADS)

Alhroob, M.; Bates, R.; Battistin, M.; Berry, S.; Bitadze, A.; Bonneau, P.; Bousson, N.; Boyd, G.; Bozza, G.; Crespo-Lopez, O.; Degeorge, C.; Deterre, C.; DiGirolamo, B.; Doubek, M.; Favre, G.; Godlewski, J.; Hallewell, G.; Hasib, A.; Katunin, S.; Langevin, N.; Lombard, D.; Mathieu, M.; McMahon, S.; Nagai, K.; O'Rourke, A.; Pearson, B.; Robinson, D.; Rossi, C.; Rozanov, A.; Strauss, M.; Vacek, V.; Zwalinski, L.

2015-03-01

Precision sound velocity measurements can simultaneously determine binary gas composition and flow. We have developed an analyzer with custom microcontroller-based electronics, currently used in the ATLAS Detector Control System, with numerous potential applications. Three instruments monitor C3F8 and CO2 coolant leak rates into the nitrogen envelopes of the ATLAS silicon microstrip and Pixel detectors. Two further instruments will aid operation of the new thermosiphon coolant recirculator: one of these will monitor air leaks into the low pressure condenser while the other will measure return vapour flow along with C3F8/C2F6 blend composition, should blend operation be necessary to protect the ATLAS silicon tracker under increasing LHC luminosity. We describe these instruments and their electronics.

Durability and Performance of Polystyrene-b-Poly(vinylbenzyl trimethylammonium) Diblock Copolymer and Equivalent Blend Anion Exchange Membranes

DTIC Science & Technology

2015-01-01

requiring circulation of the electrolyte to filter out the carbonate solids. The superior power density of proton exchange membrane fuel cells ( PEMFC ...without requir- ing a CO2 free oxidant stream, prevented commercial develop- ment of the liquid AFC, allowing PEMFCs to dominate low temperature fuel...cell research and development. PEMFCs employ a solid acidic polymer to transport protons from anode to cathode. PEMs have been researched heavily the

Hydrophilicity, pore structure and mechanical performance of CNT/PVDF materials affected by carboxyl contents in multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Zhang, Yanxia; Jiang, Ce; Tian, Run; Li, Guangfen

2018-01-01

Poly (vinylidene fluoride) (PVDF) membranes have been prepared by loading different type of MWCNTs-COOH as the dispersed phase via phase inversion method. The chemically functionalized MWCNTs with increasing carboxyl content were chosen for achieving a better dispersion in PVDF and altering the membrane hydrophilicity. The effect of the carboxyl content in MWCNTs on crystal structure, thermal behavior, membrane morphology, hydrophilicity, and water flux of blended membranes were investigated. Due to the addition of carbon nanotubes, various performances of the hybrid membrane had obvious changes. The most prominent was that thermal stability could be enhanced and the pore morphology was more preferable, also that the hydrophilicity were improved, further that water flux could be increased to some extent.

Interface design and reinforced features of arrowroot (Maranta arundinacea) starch/polyester-based membranes: Preparation, antioxidant activity, and cytocompatibility.

PubMed

Wu, Chin-San; Liao, Hsin-Tzu

2017-01-01

The structural, mechanical, antioxidant, and cytocompatibility properties of membranes prepared from the polyhydroxyalkanoate (PHA) and arrowroot (Maranta arundinacea) starch powder (ASP) blend (PHA/ASP) were studied. The acrylic acid-grafted PHA (PHA-g-AA) and the coupling agent treated ASP (TASP) were used to enhance the desired characteristics of these membranes. The PHA-g-AA/TASP membranes had better mechanical properties than the PHA/ASP membrane. This effect was attributed to greater compatibility between the grafted PHA and TASP. The water resistance of the PHA-g-AA/TASP membranes was greater than that of the PHA/ASP membranes, and a cytocompatibility evaluation with human foreskin fibroblasts (FBs) indicated that both materials were nontoxic. Moreover, both ASP and TASP enhanced the polyphenol content and antioxidant properties of the membranes. PHA-g-AA/TASP and PHA/ASP membranes had better antioxidant activity than the control group. Copyright © 2016 Elsevier B.V. All rights reserved.

HKUST-1 Membranes Anchored on Porous Substrate by Hetero MIL-110 Nanorod Array Seeds.

PubMed

Mao, Yiyin; Cao, Wei; Li, Junwei; Sun, Luwei; Peng, Xinsheng

2013-09-02

Great anchors and seeds: Hetero-seeding growth processes and anchored nanorod arrays were successfully utilized in the synthesis of HKUST-1 membranes. These arrays were firmly anchored on porous substrates by using a MIL-110 nanorod array as both the anchor and seed. The resulting HKUST-1 membranes demonstrated good separation factors for binary gases exceeding the Knudson selectivity. Copyright © 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

Presence of Fe-Al binary oxide adsorbent cake layer in ceramic membrane filtration and their impact for removal of HA and BSA.

PubMed

Kim, Kyung-Jo; Jang, Am

2018-04-01

To enhance the removal of natural organic matter (NOM) in ceramic (Ce) membrane filtration, an iron-aluminum binary oxide (FAO) was applied to the ceramic membrane surface as the adsorbent cake layer, and it was compared with heated aluminum oxide (HAO) for the evaluation of the control of NOM. Both the HAO and FAO adsorbent cake layers efficiently removed the NOM regardless of NOM's hydrophobic/hydrophilic characteristics, and the dissolved organic carbon (DOC) removal in NOM for FAO was 1-1.12 times greater than that for HAO, which means FAO was more efficient in the removal of DOC in NOM. FAO (0.03 μm), which is smaller in size than HAO (0.4 μm), had greater flux reduction than HAO. The flux reduction increased as the filtration proceeded because most of the organic foulants (colloid/particles and soluble NOM) were captured by the adsorbent cake layer, which caused fouling between the membrane surface and the adsorbent cake layer. However, no chemically irreversible fouling was observed on the Ce membrane at the end of the FAO adsorbent cake layer filtration. This means that a stable adsorbent cake layer by FAO formed on the Ce membrane, and that the reduced pure water flux of the Ce membrane, resulting from the NOM fouling, can easily be recovered through physicochemical cleaning. Copyright © 2018 Elsevier Ltd. All rights reserved.

Active zinc-blende III-nitride photonic structures on silicon

NASA Astrophysics Data System (ADS)

Sergent, Sylvain; Kako, Satoshi; Bürger, Matthias; Blumenthal, Sarah; Iwamoto, Satoshi; As, Donat Josef; Arakawa, Yasuhiko

2016-01-01

We use a layer transfer method to fabricate free-standing photonic structures in a zinc-blende AlN epilayer grown by plasma-assisted molecular beam epitaxy on a 3C-SiC pseudosubstrate and containing GaN quantum dots. The method leads to the successful realization of microdisks, nanobeam photonic crystal cavities, and waveguides integrated on silicon (100) and operating at short wavelengths. We assess the quality of such photonic elements by micro-photoluminescence spectroscopy in the visible and ultraviolet ranges, and extract the absorption coefficient of ZB AlN membranes (α ˜ (2-5) × 102 cm-1).

Modulating the Release Kinetics of Paclitaxel from Membrane-Covered Stents Using Different Loading Strategies

PubMed Central

Sydow-Plum, Georg; Haidar, Ziyad S.; Merhi, Yahye; Tabrizian, Maryam

2008-01-01

Membrane-covered Express2TM Monorail® stents composed of chitosan (CH) blended with polyethylene oxide (PEO) in 70:30% wt (CH-PEO) were coated with a monolayer of hyaluronic acid (HA). This significantly improved the resistance to platelet adhesion and demonstrated excellent mechanical properties, resisting the harsh conditions during stent crimping and subsequent inflation. CH-PEO/HA membrane was then combined with a paclitaxel (Pac) delivery system via three different approaches for comparison of release profiles of Pac. The activity of Pac in these systems was confirmed since its presence in the membrane significantly decreased cell viability of U937 macrophages. Presented results are promising for applications requiring different release patterns of hydrophobic drugs.

Transport properties of proton-exchange membranes: Effect of supercritical-fluid processing and chemical functionality

NASA Astrophysics Data System (ADS)

Pulido Ayazo

NafionRTM membranes commonly used in direct methanol fuel cells (DMFC), are tipically limited by high methanol permeability (also known as the cross-over limitation). These membranes have phase segregated sulfonated ionic domains in a perfluorinated backbone, which makes processing challenging and limited by phase equilibria considerations. This study used supercritical fluids (SCFs) as a processing alternative, since the gas-like mass transport properties of SCFs allow a better penetration into the membranes and the use of polar co-solvents influenced their morphology, fine-tuning the physical and transport properties in the membrane. Measurements of methanol permeability and proton conductivity were performed to the NafionRTM membranes processed with SCFs at 40ºC and 200 bar and the co-solvents as: acetone, tetrahydrofuran (THF), isopropyl alcohol, HPLC-grade water, acetic acid, cyclohexanone. The results obtained for the permeability data were of the order of 10 -8-10-9 cm2/s, two orders of magnitude lower than unprocessed Nafion. Proton conductivity results obtained using AC impedance electrochemical spectroscopy was between 0.02 and 0.09 S/cm, very similar to the unprocessed Nafion. SCF processing with ethanol as co-solvent reduced the methanol permeability by two orders of magnitude, while the proton conductivity was only reduced by 4%. XRD analysis made to the treated samples exhibited a decreasing pattern in the crystallinity, which affects the transport properties of the membrane. Also, SAXS profiles of the Nafion membranes processed were obtained with the goal of determining changes produced by the SCF processing in the hydrophilic domains of the polymer. With the goal of searching for new alternatives in proton exchange membranes (PEMs) triblock copolymer of poly(styrene-isobutylene-styrene) (SIBS) and poly(styrene-isobutylene-styrene) SEBS were studied. These sulfonated tri-block copolymers had lower methanol permeabilities, but also lower proton conductivity, even with blends of these and blends with Nafion membranes. Other alternative studied was the functionalization of the membranes SIBS with metallic cations, which decreased the methanol permeability in the membranes containing the cations Mg2+, Zn2+ and Al 3+, while the proton conductivity was maintained more or less constant. The permeation of methanol vapor was investigated and the behavior through the membranes studied followed a pattern of Fick's Law, while the pattern shown by the permeation in liquid phase was non-Fickian.

ATG14 promotes membrane tethering and fusion of autophagosomes to endolysosomes.

PubMed

Diao, Jiajie; Liu, Rong; Rong, Yueguang; Zhao, Minglei; Zhang, Jing; Lai, Ying; Zhou, Qiangjun; Wilz, Livia M; Li, Jianxu; Vivona, Sandro; Pfuetzner, Richard A; Brunger, Axel T; Zhong, Qing

2015-04-23

Autophagy, an important catabolic pathway implicated in a broad spectrum of human diseases, begins by forming double membrane autophagosomes that engulf cytosolic cargo and ends by fusing autophagosomes with lysosomes for degradation. Membrane fusion activity is required for early biogenesis of autophagosomes and late degradation in lysosomes. However, the key regulatory mechanisms of autophagic membrane tethering and fusion remain largely unknown. Here we report that ATG14 (also known as beclin-1-associated autophagy-related key regulator (Barkor) or ATG14L), an essential autophagy-specific regulator of the class III phosphatidylinositol 3-kinase complex, promotes membrane tethering of protein-free liposomes, and enhances hemifusion and full fusion of proteoliposomes reconstituted with the target (t)-SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) syntaxin 17 (STX17) and SNAP29, and the vesicle (v)-SNARE VAMP8 (vesicle-associated membrane protein 8). ATG14 binds to the SNARE core domain of STX17 through its coiled-coil domain, and stabilizes the STX17-SNAP29 binary t-SNARE complex on autophagosomes. The STX17 binding, membrane tethering and fusion-enhancing activities of ATG14 require its homo-oligomerization by cysteine repeats. In ATG14 homo-oligomerization-defective cells, autophagosomes still efficiently form but their fusion with endolysosomes is blocked. Recombinant ATG14 homo-oligomerization mutants also completely lose their ability to promote membrane tethering and to enhance SNARE-mediated fusion in vitro. Taken together, our data suggest an autophagy-specific membrane fusion mechanism in which oligomeric ATG14 directly binds to STX17-SNAP29 binary t-SNARE complex on autophagosomes and primes it for VAMP8 interaction to promote autophagosome-endolysosome fusion.

Durable vesicles for reconstitution of membrane proteins in biotechnology.

PubMed

Beales, Paul A; Khan, Sanobar; Muench, Stephen P; Jeuken, Lars J C

2017-02-08

The application of membrane proteins in biotechnology requires robust, durable reconstitution systems that enhance their stability and support their functionality in a range of working environments. Vesicular architectures are highly desirable to provide the compartmentalisation to utilise the functional transmembrane transport and signalling properties of membrane proteins. Proteoliposomes provide a native-like membrane environment to support membrane protein function, but can lack the required chemical and physical stability. Amphiphilic block copolymers can also self-assemble into polymersomes: tough vesicles with improved stability compared with liposomes. This review discusses the reconstitution of membrane proteins into polymersomes and the more recent development of hybrid vesicles, which blend the robust nature of block copolymers with the biofunctionality of lipids. These novel synthetic vesicles hold great promise for enabling membrane proteins within biotechnologies by supporting their enhanced in vitro performance and could also contribute to fundamental biochemical and biophysical research by improving the stability of membrane proteins that are challenging to work with. © 2017 The Author(s).

Assessment of environmentally friendly fuel emissions from in-use vehicle exhaust: low-blend iso-stoichiometric GEM mixture as example.

PubMed

Schifter, Isaac; Díaz-Gutiérrez, Luis; Rodríguez-Lara, René; González-Macías, Carmen; González-Macías, Uriel

2017-05-01

Gasoline-ethanol-methanol fuel blends were formulated with the same stoichiometric air-to-fuel ratio and volumetric energy concentration as any binary ethanol-gasoline blend. When the stoichiometric blends operated in a vehicle, the time period, injector voltage, and pressure for each fuel injection event in the engine corresponded to a given stoichiometric air-to-fuel ratio, and the load was essentially constant. Three low oxygen content iso-stoichiometric ternary gasoline-ethanol-methanol fuel blends were prepared, and the properties were compared with regular-type fuel without added oxygen. One of the ternary fuels was tested using a fleet of in-use vehicles for15 weeks and compared to neat gasoline without oxygenated compounds as a reference. Only a small number of publications have compared these ternary fuels in the same engine, and little data exist on the performance and emissions of in-use spark-ignition engines. The total hydrocarbon emissions observed was similar in both fuels, in addition to the calculated ozone forming potential of the tailpipe and evaporative emissions. In ozone non-attainment areas, the original purpose for oxygenate gasolines was to decrease carbon monoxide emissions. The results suggest that the strategy is less effective than expected because there still exist a great number of vehicles that have suffered the progressive deterioration of emissions and do not react to oxygenation, while new vehicles are equipped with sophisticated air/fuel control systems, and oxygenation does not improve combustion because the systems adjust the stoichiometric point, making it insensitive to the origin of the added excess oxygen (fuel or excess air). Graphical abstract Low level ternary blend of gasoline-ethanol-methanol were prepared with the same stoichiometric air-fuel ratio and volumetric energy concentration, based on the volumetric energy density of the pre-blended components. Exhaust and evaporative emissions was compared with a blend having no oxygen in a fleet of 12 in-use vehicles. Vehicles that had suffer a normal deterioration of emissions and do not react to oxygenation, and new vehicles with more sophisticated air/fuel control systems do not improve combustion.

Clostridium difficile binary toxin CDT

PubMed Central

Gerding, Dale N; Johnson, Stuart; Rupnik, Maja; Aktories, Klaus

2014-01-01

Binary toxin (CDT) is frequently observed in Clostridium difficile strains associated with increased severity of C. difficile infection (CDI). CDT belongs to the family of binary ADP-ribosylating toxins consisting of two separate toxin components: CDTa, the enzymatic ADP-ribosyltransferase which modifies actin, and CDTb which binds to host cells and translocates CDTa into the cytosol. CDTb is activated by serine proteases and binds to lipolysis stimulated lipoprotein receptor. ADP-ribosylation induces depolymerization of the actin cytoskeleton. Toxin-induced actin depolymerization also produces microtubule-based membrane protrusions which form a network on epithelial cells and increase bacterial adherence. Multiple clinical studies indicate an association between binary toxin genes in C. difficile and increased 30-d CDI mortality independent of PCR ribotype. Further studies including measures of binary toxin in stool, analyses of CDI mortality caused by CDT-producing strains, and examination of the relationship of CDT expression to TcdA and TcdB toxin variants and PCR ribotypes are needed. PMID:24253566

Largely enhanced dielectric properties of carbon nanotubes/polyvinylidene fluoride binary nanocomposites by loading a few boron nitride nanosheets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Minhao; Zhao, Hang; He, Delong

2016-08-15

The ternary nanocomposites of boron nitride nanosheets (BNNSs)/carbon nanotubes (CNTs)/polyvinylidene fluoride (PVDF) are fabricated via a combination of solution casting and extrusion-injection processes. The effects of BNNSs on the electrical conductivity, dielectric behavior, and microstructure changes of CNTs/PVDF binary nanocomposites are systematically investigated. A low percolation value (f{sub c}) for the CNTs/PVDF binary system is obtained due to the integration of solution and melting blending procedures. Two kinds of CNTs/PVDF binary systems with various CNTs contents (f{sub CNTs}) as the matrix are discussed. The results reveal that compared with CNTs/PVDF binary systems at the same f{sub CNTs}, the ternary BNNSs/CNTs/PVDFmore » nanocomposites exhibit largely enhanced dielectric properties due to the improvement of the CNTs dispersion state and the conductive network. The dielectric constant of CNTs/PVDF binary nanocomposite with 6 vol. % CNTs (f{sub CNTs} < f{sub c}) shows a 79.59% enhancement from 49 to 88 after the incorporation of 3 vol. % BNNSs. For the other CNTs/PVDF system with 8 vol. % CNTs (f{sub CNTs} > f{sub c}), it displays a 43.32% improvement from 1325 to 1899 after the addition of 3 vol. % BNNSs. The presence of BNNSs facilitates the formation of the denser conductive network. Meanwhile, the ternary BNNSs/CNTs/PVDF systems exhibit a low dielectric loss. The adjustable dielectric properties could be obtained by employing the ternary systems due to the microstructure changes of nanocomposites.« less

Solubility enhancement of miconazole nitrate: binary and ternary mixture approach.

PubMed

Rai, Vineet Kumar; Dwivedi, Harinath; Yadav, Narayan Prasad; Chanotiya, Chandan Singh; Saraf, Shubhini A

2014-08-01

Enhancement of aqueous solubility of very slightly soluble Miconazole Nitrate (MN) is required to widen its application from topical formulation to oral/mucoadhesive formulations. Aim of the present investigation was to enhance the aqueous solubility of MN using binary and ternary mixture approach. Binary mixtures such as solvent deposition, inclusion complexation and solid dispersion were adopted to enhance solubility using different polymers like lactose, beta-cyclodextrin (β-CD) and polyethylene-glycol 6000 (PEG 6000), respectively. Batches of binary mixtures with highest solubility enhancement potentials were further mixed to form ternary mixture by a simple kneading method. Drug polymer interaction and mixture morphology was studied using the Fourier transform infrared spectroscopy and the scanning electron microscopy, respectively along with their saturation solubility studies and drug release. An excellent solubility enhancement, i.e. up to 72 folds and 316 folds of MN was seen by binary and ternary mixture, respectively. Up to 99.5% drug was released in 2 h from the mixtures of MN and polymers. RESULTS revealed that solubility enhancement by binary mixtures is achieved due to surface modification and by increasing wettability of MN. Tremendous increase in solubility of MN by ternary mixture could possibly be due to blending of water soluble polymers, i.e. lactose and PEG 6000 with β-CD which was found to enhance the solubilizing nature of β-CD. Owing to the excellent solubility enhancement potential of ternary mixtures in enhancing MN solubility from 110.4 μg/ml to 57640.0 μg/ml, ternary mixture approach could prove to be promising in the development of oral/mucoadhesive formulations.

Performance Enhancement of Polymer Solar Cells by Using Two Polymer Donors with Complementary Absorption Spectra.

PubMed

Lu, Heng; Zhang, Xuejuan; Li, Cuihong; Wei, Hedi; Liu, Qian; Li, Weiwei; Bo, Zhishan

2015-07-01

Performance enhancement of polymer solar cells (PSCs) is achieved by expanding the absorption of the active layer of devices. To better match the spectrum of solar radiation, two polymers with different band gaps are used as the donor material to fabricate ternary polymer cells. Ternary blend PSCs exhibit an enhanced short-circuit current density and open-circuit voltage in comparison with the corresponding HD-PDFC-DTBT (HD)- and DT-PDPPTPT (DPP)-based binary polymer solar cells, respectively. Ternary PSCs show a power conversion efficiency (PCE) of 6.71%, surpassing the corresponding binary PSCs. This work demonstrates that the fabrication of ternary PSCs by using two polymers with complementary absorption is an effective way to improve the device performance. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of fuel additives for reduction of material imcompatibilities in methanol-gasoline blends

NASA Technical Reports Server (NTRS)

Rodriguez, C. F.; Barbee, J. G.; Knutson, W. K.; Cuellar, J. P., Jr.

1983-01-01

Screening tests determined the efficacy of six commercially available additives as modifiers of methanol's corrosivity toward metals and its weakening of tensile properties of nonmetals in automotive fuel systems. From the screening phase, three additives which seemed to protect some of the metals were tested in higher concentrations and binary combinations in search of optimal application conditions. Results indicate that two of the additives have protective properties and combining them increases the protection of the metals corroded by methanol-gasoline blends. Half of the metals in the tests were not corroded. Testing at recommended concentrations and then at higher concentrations and in combinations shows that the additives would have no protective or harmful effects on the nonmetals. Two additives emerged as candidates for application to the protection of metals in automotive methanol-gasoline fuel systems. The additives tested were assigned letter codes to protect their proprietary nature.

Vertical phase separation in bulk heterojunction solar cells formed by in situ polymerization of fulleride

PubMed Central

Zhang, Lipei; Xing, Xing; Zheng, Lingling; Chen, Zhijian; Xiao, Lixin; Qu, Bo; Gong, Qihuang

2014-01-01

Vertical phase separation of the donor and the acceptor in organic bulk heterojunction solar cells is crucial to improve the exciton dissociation and charge transport efficiencies. This is because whilst the exciton diffusion length is limited, the organic film must be thick enough to absorb sufficient light. However, it is still a challenge to control the phase separation of a binary blend in a bulk heterojunction device architecture. Here we report the realization of vertical phase separation induced by in situ photo-polymerization of the acrylate-based fulleride. The power conversion efficiency of the devices with vertical phase separation increased by 20%. By optimising the device architecture, the power conversion efficiency of the single junction device reached 8.47%. We believe that in situ photo-polymerization of acrylate-based fulleride is a universal and controllable way to realise vertical phase separation in organic blends. PMID:24861168

Dimensionally stable metallic hydride composition

DOEpatents

Heung, Leung K.

1994-01-01

A stable, metallic hydride composition and a process for making such a composition. The composition comprises a uniformly blended mixture of a metal hydride, kieselguhr, and a ballast metal, all in the form of particles. The composition is made by subjecting a metal hydride to one or more hydrogen absorption/desorption cycles to disintegrate the hydride particles to less than approximately 100 microns in size. The particles are partly oxidized, then blended with the ballast metal and the kieselguhr to form a uniform mixture. The mixture is compressed into pellets and calcined. Preferably, the mixture includes approximately 10 vol. % or more kieselguhr and approximately 50 vol. % or more ballast. Metal hydrides that can be used in the composition include Zr, Ti, V, Nb, Pd, as well as binary, tertiary, and more complex alloys of La, Al, Cu, Ti, Co, Ni, Fe, Zr, Mg, Ca, Mn, and mixtures and other combinations thereof. Ballast metals include Al, Cu and Ni.

Chitosan and alginate types of bio-membrane in fuel cell application: An overview

NASA Astrophysics Data System (ADS)

Shaari, N.; Kamarudin, S. K.

2015-09-01

The major problems of polymer electrolyte membrane fuel cell technology that need to be highlighted are fuel crossovers (e.g., methanol or hydrogen leaking across fuel cell membranes), CO poisoning, low durability, and high cost. Chitosan and alginate-based biopolymer membranes have recently been used to solve these problems with promising results. Current research in biopolymer membrane materials and systems has focused on the following: 1) the development of novel and efficient biopolymer materials; and 2) increasing the processing capacity of membrane operations. Consequently, chitosan and alginate-based biopolymers seek to enhance fuel cell performance by improving proton conductivity, membrane durability, and reducing fuel crossover and electro-osmotic drag. There are four groups of chitosan-based membranes (categorized according to their reaction and preparation): self-cross-linked and salt-complexed chitosans, chitosan-based polymer blends, chitosan/inorganic filler composites, and chitosan/polymer composites. There are only three alginate-based membranes that have been synthesized for fuel cell application. This work aims to review the state-of-the-art in the growth of chitosan and alginate-based biopolymer membranes for fuel cell applications.

Modulation of the interface between polyester and spent coffee grounds in polysaccharide membranes: Preparation, cell proliferation, antioxidant activity and tyrosinase activity.

PubMed

Wu, Chin-San

2017-09-01

The structural, antioxidant and cytocompatibility properties of membranes prepared from polyhydroxyalkanoate (PHA) and spent coffee ground (SCG) blends (PHA/SCG) were studied. Acrylic acid-grafted PHA (PHA-g-AA) was used to enhance the desirable characteristics of these membranes, which had better tensile properties than the corresponding PHA/SCG membranes. The water resistance of the PHA-g-AA/SCG membranes was greater than that of the PHA/SCG membranes, and a cytocompatibility evaluation with mouse normal tail fibroblasts (FBs) indicated that both materials were nontoxic. Cell cycle assays of FBs on PHA/SCG and PHA-g-AA/SCG membrane samples were not affected by the DNA content related to damage. Moreover, SCG enhanced the saccharide and polyphenol contents, and antioxidant properties, of the PHA-g-AA/SCG and PHA/SCG membranes. Therefore, we analysed the effects of these compounds' membranes on melanogenesis in B16-F10 melanoma cells. The results demonstrated that PHA/SCG and PHA-g-AA/SCG membranes reduced cellular tyrosinase activities in vitro. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation and characterization of novel zwitterionic poly(arylene ether sulfone) ultrafiltration membrane with good thermostability and excellent antifouling properties

NASA Astrophysics Data System (ADS)

Rong, Guolong; Zhou, Di; Han, Xiaocui; Pang, Jinhui

2018-01-01

Zwitterionic poly(arylene ether sulfone) (PAES-NS) was synthesized via copolymerization by using a bisphenol monomer with a pyridine group. The chemical structures of the copolymers were confirmed by using Fourier transform infrared (FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopy; the copolymers showed good thermal stability. A series of polyphenysulfone (PPSU)/PAES-NS blend ultrafiltration (UF) membranes was prepared via conventional immersion precipitation phase inversion methods The morphologies of the modified membranes were investigated by scanning electron microscopy (SEM). The surface hydrophilicity of the UF membranes was studied by water contact angle measurement, indicating that the zwitterionic group increased the membrane hydrophilicity. UF of solvated model pollutants using the membranes showed a significant reduction of the irreversible adsorption of the foulants, illustrating the excellent anti-fouling properties of the membrane. The water flux of the PAES-NS membrane was significantly enhanced, being almost three times higher than that of the pristine PPSU membrane, with retention of a high rejection level. After three UF cycles, the water flux recovery of the PAES-NS membrane was as high as 96%.

Melting Point and Viscosity Behavior of High Energy Density Missile Fuels

DTIC Science & Technology

1982-09-01

CLASSIFICATION OF THIS PAGE (f,n Date Eneed . etrahydrodi(cyclopentadiene) ( XTHDCPD or JP-lO). HNN and HXX each have two crystalline forms. The solid-solid...suggesting solid solution formation on crystallization. The experimental m.p. curves for the binary/isomer I - XTHDCPD system could be used to predict m.p...liquidus temperature, of any/fuel blend of HNN, HXX, isomer I and XTHDCPD of kno composition. It )as found that the maximum m.p. specification of -54 C

A new mechanism for selective adsorption of rubber on carbon black surface caused by nano-confinement in SBR/NBR solution

NASA Astrophysics Data System (ADS)

Kawazoe, Masayuki

A novel mechanism of selective adsorption of rubber molecules onto carbon black surface in a binary immiscible rubber blend solution has been proposed in this dissertation. The phenomenon leads to uneven distribution of carbon black to the specific polymer in the blend and the obtained electrically conductive composite showed drastic reduction of percolation threshold concentration (PTC). The mechanism and the feature of conductive network formation have much potential concerning both fundamental understanding and industrial application to improve conductive polymer composites. In chapter I, carbon black filled conductive polymer composites are briefly reviewed. Then, in chapter II, a mechanism of rubber molecular confinement into carbon black aggregate structure is introduced to explain the selective adsorption of a specific rubber onto carbon black surface in an immiscible rubber solution blend (styrene butadiene rubber (SBR) and acrylonitrile butadiene rubber (NBR) with toluene or chloroform). Next, in chapters III and IV, polymers with various radius of gyration (Rg) and carbon blacks with various aggregate structure are examined to verify the selective adsorption mechanism. Finally, in chapter V, the novel mechanism was applied to create unique meso-/micro-unit conductive network in carbon black dispersed SBR/NBR composites.

Polymer Solar Cells with 90% External Quantum Efficiency Featuring an Ideal Light- and Charge-Manipulation Layer.

PubMed

Chen, Jing-De; Li, Yan-Qing; Zhu, Jingshuai; Zhang, Qianqian; Xu, Rui-Peng; Li, Chi; Zhang, Yue-Xing; Huang, Jing-Sheng; Zhan, Xiaowei; You, Wei; Tang, Jian-Xin

2018-03-01

Rapid progress in the power conversion efficiency (PCE) of polymer solar cells (PSEs) is beneficial from the factors that match the irradiated solar spectrum, maximize incident light absorption, and reduce photogenerated charge recombination. To optimize the device efficiency, a nanopatterned ZnO:Al 2 O 3 composite film is presented as an efficient light- and charge-manipulation layer (LCML). The Al 2 O 3 shells on the ZnO nanoparticles offer the passivation effect that allows optimal electron collection by suppressing charge-recombination loss. Both the increased refractive index and the patterned deterministic aperiodic nanostructure in the ZnO:Al 2 O 3 LCML cause broadband light harvesting. Highly efficient single-junction PSCs for different binary blends are obtained with a peak external quantum efficiency of up to 90%, showing certified PCEs of 9.69% and 13.03% for a fullerene blend of PTB7:PC 71 BM and a nonfullerene blend, FTAZ:IDIC, respectively. Because of the substantial increase in efficiency, this method unlocks the full potential of the ZnO:Al 2 O 3 LCML toward future photovoltaic applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interstitial micelles in binary blends of A B A triblock copolymers and homopolymers

NASA Astrophysics Data System (ADS)

Wołoszczuk, S.; Banaszak, M.

2018-01-01

We investigate triblock-homopolymer blends of types A1BA2/A and A1BA2/B, using a lattice Monte Carlo method. While the simulated triblock chains are compositionally symmetric in terms of the A-to-B volume ratio, the A1 block is significantly shorter than the A2 block. For the pure A1BA2 melt and the A1BA2 solutions in selective solvent the phase behavior is relatively well known, including existence and stability of the interstitial micelles which were discovered in previous Monte Carlo simulations. In this paper we study the stability of the interstitial micelles as a function of triblock volume fraction in selective homopolymers of either type A or type B, using two significantly different homopolymer chain lengths. We found that adding selective homopolymer of type A shifts the stability of the interstitial micelles into significantly higher temperatures. We also obtained, via self-assembly, intriguing new nanostructures which can be identified as ordered truncated octahedra. Finally, we established that the phase behavior of the triblock-homopolymer blends depends relatively weakly on the chain length of the added homopolymer.

Separation of methane-nitrogen mixtures using synthesis vertically aligned carbon nanotube membranes

NASA Astrophysics Data System (ADS)

Gilani, Neda; Daryan, Jafar Towfighi; Rashidi, Alimorad; Omidkhah, Mohammad Reza

2012-03-01

In this paper, capabilities of carbon nanotube (CNT) membranes fabricated in cylindrical pores of anodic aluminum oxide (AAO) substrate to separate the binary mixtures of CH4/N2 are studied experimentally. For this purpose, the permeability and selectivity of three CNT/AAO membranes with different growth time as 6 h, 12 h and 18 h are investigated. CNTs are grown vertically through holes of AAO with average pore diameter of 45 nm by chemical vapor deposition (CVD) of acetylene gas. CNT/AAO membranes with the same CNTs' outer diameters and different inner diameters are synthesized. The AAO are characterized by SEM analysis. In addition, SEM, TEM, BET N2 adsorption analysis and Raman spectroscopy are employed to characterize aligned CNTs. Study on permeability and selectivity of membranes for three binary mixtures of CH4/N2 showed that when the CNT inner diameters are 34 nm and 24 nm, viscous flow is the governing mechanism and insignificant selectivities of 1.2-1.24 are achieved. However, the membrane with CNT inner diameter and wall thickness of 8 nm and 16 nm respectively is considerably selective for CH4 over N2. It was also found that CH4 mole fraction in the feed and upstream feed pressure have major effect on permeability and selectivity. The membrane with 18 h synthesis time showed the selectivity is in the range of 1.8-3.85. The enhancement factor for N2 single gas diffusivity was also found to be about three times larger than that predicted by Knudsen diffusion model.

Zirconium-based metal organic frameworks loaded on polyurethane foam membrane for simultaneous removal of dyes with different charges.

PubMed

Li, Juan; Gong, Ji-Lai; Zeng, Guang-Ming; Zhang, Peng; Song, Biao; Cao, Wei-Cheng; Liu, Hong-Yu; Huan, Shuang-Yan

2018-10-01

Treating dye wastewater by membrane filtration technology has received much attention from researchers all over the world, however, current studies mainly focused on the removal of singly charged dyes but actual wastewater usually contains dyes with different charges. In this study, the removal of neutral, cationic and anionic dyes in binary or ternary systems was conducted by using zirconium-based metal organic frameworks loaded on polyurethane foam (Zr-MOFs-PUF) membrane. The Zr-MOFs-PUF membrane was fabricated by an in-situ hydrothermal synthesis approach and a hot-pressing process. Neutrally charged Rhodamine B (RB), positively charged Methylene blue (MB), and negatively charged Congo red (CR) were chosen as model pollutants for investigating filtration performance of the membrane. The results of filtration experiments showed that the Zr-MOFs-PUF membrane could simultaneously remove RB, MB, and CR not only from their binary system including RB/MB, RB/CR, and MB/CR mixtures, but also from RB/MB/CR ternary system. The removal of dyes by Zr-MOFs-PUF membrane was mainly attributed to the electrostatic interactions, hydrogen bond interaction, and Lewis acid-base interactions between the membrane and dye molecules. The maximum removal efficiencies by Zr-MOFs-PUF membrane were 98.80% for RB at pH ≈ 7, 97.57% for MB at pH ≈ 9, and 87.39% for CR at pH ≈ 3. Additionally, when the NaCl concentration reached 0.5 mol/L in single dye solutions, the removal efficiencies of RB, MB, and CR by Zr-MOFs-PUF membrane were 93.08%, 79.52%, and 97.82%, respectively. All the results suggested that the as-prepared Zr-MOFs-PUF membrane has great potential in practical treatment of dye wastewater. Copyright © 2018 Elsevier Inc. All rights reserved.

Preparation and study on the structure of keratin/PVA membrane containing wool fibers

NASA Astrophysics Data System (ADS)

Wu, Min; Shen, Shuming; Yang, Xuhong; Tang, Rencheng

2017-10-01

The urea / sodium sulfide / sodium dodecyl sulfate (SDS) method was used to dissolve the wool in this study. Then the Wool fiber/keratin/PVA composites with different proportions were prepared, and the surface morphology, molecular structure, mechanical property of the composite films and the influence of the proportions on their structure and properties were studied. The results showed that, there are α-helix structure, β-sheet and random coil conformations in the pure keratin film, as well as in the wool fiber. Compared with wool fiber, the crystallinity of keratin decreased. PVA can obviously improve the mechanical property of the blended film. When the blended ratio of keratin/PVA is 20/80, the mechanical property of the blended film is greatly improved. The composite films with 8%-16% of wool fibers have better flexibility than those without wool fibers.

Polyester polymer alloy as a high-performance membrane.

PubMed

Igoshi, Tadaaki; Tomisawa, Narumi; Hori, Yoshinori; Jinbo, Yoichi

2011-01-01

Polyester polymer alloy (PEPA) membrane is developed as a synthetic polymermembrane. It consists of two polymers - polyethersulfone (PES) and polyarylate (PAR).The pore size in membrane can be controlled by a blend ratio of PES and PAR. One unique characteristic is that PEPA membrane has three layers of a skin layer on the inner surface, a porous layer in the membrane, and a skin layer on the outer surface, respectively. The permeability of water and substances is controlled by the skin layer on the inner surface. PEPA membrane dialyzer can be adequately considered as a high-performance dialyzer. Furthermore, the skin layer on the outer surface can block endotoxin from the dialysis fluid side. PEPA membrane can therefore be used as an endotoxin-retentive filter. The other unique characteristic is that each amount of albumin loss or β2-microglobulin removal can be controlled by an additive amount of polyvinylpyrrolidone. This means that the PEPA dialyzer can be clinically used to meet the conditions of the patient. Copyright © 2011 S. Karger AG, Basel.

The effects of surface-charged submicron polystyrene particles on the structure and performance of PSF forward osmosis membrane

NASA Astrophysics Data System (ADS)

Zuo, Hao-Ran; Fu, Jia-Bei; Cao, Gui-Ping; Hu, Nian; Lu, Hui; Liu, Hui-Qing; Chen, Peng-Peng; Yu, Jie

2018-04-01

Monodisperse surface-charged submicron polystyrene particles were designed, synthesized, and blended into polysulfone (PSF) support layer to prepare forward osmosis (FO) membrane with high performance. The membrane incorporated with particles were characterized with respect to morphology, porosity, and internal osmotic pressure (IOP). Results showed that the polymer particles not only increased the hydrophilicity and porosity of support layer, but also generated considerable IOP, which helped markedly decreasing the structure parameter from 1550 to 670 μm. The measured mass transfer parameters further confirmed the beneficial effects of the surface-charged submicron polymer particles on the performance of FO membrane. For instance, the water permeability coefficient (5.37 L m-2 h-1 bar-1) and water flux (49.7 L m-2 h-1) of the FO membrane incorporated with 5 wt% particles were almost twice as much as that of FO membrane without incorporation. This study suggests that monodisperse surface-charged submicron polymer particles are potential modifiers for improving the performance of FO membranes.

The population of single and binary white dwarfs of the Galactic bulge

NASA Astrophysics Data System (ADS)

Torres, S.; García-Berro, E.; Cojocaru, R.; Calamida, A.

2018-05-01

Recent Hubble Space Telescope observations have unveiled the white dwarf cooling sequence of the Galactic bulge. Although the degenerate sequence can be well fitted employing the most up-to-date theoretical cooling sequences, observations show a systematic excess of red objects that cannot be explained by the theoretical models of single carbon-oxygen white dwarfs of the appropriate masses. Here, we present a population synthesis study of the white dwarf cooling sequence of the Galactic bulge that takes into account the populations of both single white dwarfs and binary systems containing at least one white dwarf. These calculations incorporate state-of-the-art cooling sequences for white dwarfs with hydrogen-rich and hydrogen-deficient atmospheres, for both white dwarfs with carbon-oxygen and helium cores, and also take into account detailed prescriptions of the evolutionary history of binary systems. Our Monte Carlo simulator also incorporates all the known observational biases. This allows us to model with a high degree of realism the white dwarf population of the Galactic bulge. We find that the observed excess of red stars can be partially attributed to white dwarf plus main sequence binaries, and to cataclysmic variables or dwarf novae. Our best fit is obtained with a higher binary fraction and an initial mass function slope steeper than standard values, as well as with the inclusion of differential reddening and blending. Our results also show that the possible contribution of double degenerate systems or young and thick-discbulge stars is negligible.

An L+T Spectral Binary with Possible AB Doradus Kinematics

NASA Astrophysics Data System (ADS)

Bardalez Gagliuffi, Daniella C.; Gagné, Jonathan; Faherty, Jacqueline K.; Burgasser, Adam J.

2018-02-01

We present the identification of WISE J135501.90‑825838.9 as a spectral binary system with a slight possibility of planetary-mass components in the 130–200 Myr AB Doradus moving group. Peculiarities in the near-infrared spectrum of this source suggest it to be a blended-light binary with L6.0 ± 1.0 and T3.0 ± 1.8 or L7.0 ± 0.6 and T7.5 ± 0.4 components. Its proper motion and radial velocity as a combined-light source yield a high membership probability for AB Doradus. While the young L6+T3 case is underluminous in a color–magnitude diagram at the AB Doradus kinematic distance, the young L7+T7.5 case could be viable. Gravity-sensitive indicators are more consistent with a field-age binary. If confirmed as a young object member of AB Doradus, we estimate masses of 11 ± 1 M Jup and 9 ± 1 M Jup with both component masses below the Deuterium-burning mass limit. Otherwise, we find masses of {72}-5+4 and {61}-8+6 for the field L6+T3 case and {70}-4+2 and {42}-6+5 for the field L7+T7.5 case. Our identification of WISE J135501.90‑825838.9 as a candidate young spectral binary introduces a new technique for detecting and characterizing planetary-mass companions to young brown dwarfs.

LDPE/PHB blends filled with castor oil cake

NASA Astrophysics Data System (ADS)

Burlein, Gustavo A.; Rocha, Marisa C. G.

2015-05-01

The response surface methodology (RSM) is a collection of mathematical techniques useful for developing, improving and optimizing process. In this study, RSM technique was applied to evaluate the effect of the components proportion on the mechanical properties of low density polyethylene (LDPE)/ poly (3-hydroxy-butyrate) (PHB) blends filled with castor oil cake (CC). The blends were prepared by melt mixing in a twin screw extruder. Low density polyethylene, poly (3-hydroxy-butyrate) and castor oil pressed cake were represented by the input variables designated as LDPE, PHB and CC, respectively. As it was desirable to consider the largest LDPE content in the ternary system, the components of the mixture were subjected to the following constraints: 0.7 ≤ LDPE ≤ 1.0, 0≤ PHB≤0.3 e 0 ≤ CC ≤0.3. The mechanical properties of the different mixtures were determined by conventional ASTM tests and were evaluated through analysis of variance performed by the Minitab software. Some polynomial equations were tested in order to describe the mechanical behavior of the samples. The quadratic model in pseudo components was selected for describing the tensile behavior because it was the most efficient from a statistical point of view (p-value ≤ 0.05; coefficient of determination (r2) close to 1 and variation inflation factor (VIF) values < 5). The results showed that the LDPE Young's modulus increases but the other tensile properties and impact resistance deteriorate with the addition of PHB or CC. The tensile strength values of binary mixtures of LDPE lie in the range from 8.9 to 10 MPa. As some commercial grades of LDPE have mechanical strength in this range, it may be inferred that the addition of a certain amount of PHB or CC to LDPE may be considered as a possibility for obtaining LDPE based materials with increased susceptibility to biodegradation. The cubic model in pseudo components was selected for describe the flexural strength of the samples because it was the most adequate from a statistical point of view. However, the linear model in pseudo components was the most efficient to describe the flexural modulus of the samples. The results obtained show that superior LDPE flexural properties may be obtained by the addition of PHB or castor oil cake to LDPE. The morphological study of the materials obtained showed that LDPE/PHB blends are immiscible and form morphological structures with well distinguished phase boundaries between dispersed phase and matrix. Biodegradation was evaluated burying the samples in simulated soil for different periods of time. The LDPE/PHB/CC mixtures with higher content of PHB showed more pronounced degradation. Under the experimental conditions studied the LDPE/CC compositions presented no degradation. However, the loss of mass of the LDPE/PHB/CC mixtures was higher than the loss of mass of the corresponding LDPE/PHB binary blend. This result suggests that the castor oil cake accelerates the degradation of the LDPE/PHB blends.

Controlled Antibiotics Release System through Simple Blended Electrospun Fibers for Sustained Antibacterial Effects.

PubMed

Zhang, Zixin; Tang, Jianxiong; Wang, Heran; Xia, Qinghua; Xu, Shanshan; Han, Charles C

2015-12-09

Implantation of sustained antibacterial system after abdominal surgery could effectively prevent complicated intra-abdominal infection. In this study, a simple blended electrospun membrane made of poly(D,L-lactic-co-glycolide) (PLGA)/poly(dioxanone) (PDO)/Ciprofloxacin hydrochloride (CiH) could easily result in approximately linear drug release profile and sustained antibacterial activity against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The addition of PDO changed the stack structure of PLGA, which in turn influenced the fiber swelling and created drug diffusion channels. It could be a good candidate for reducing postoperative infection or be associated with other implant to resist biofilm formation.

Impact of swelling characteristics on the permselective properties of multi-layer composite membranes for water removal from alcohols.

EPA Science Inventory

The removal of water from organic solvents and biofuels, including lower alcohols (i.e., methanol, ethanol, propanol, and butanol), is necessary for the production, blending, and reuse of those organic compounds. Water forms an azeotrope with many hydrophilic solvents, complicati...

A carbon nanotube-infused polysulfone membrane with polyvinyl alcohol layer for treating oil-containing waste water

PubMed Central

Maphutha, Selby; Moothi, Kapil; Meyyappan, M.; Iyuke, Sunny E.

2013-01-01

A carbon nanotube (CNT) integrated polymer composite membrane with a polyvinyl alcohol barrier layer has been prepared to separate oil from water for treatment of oil-containing waste water. The CNTs were synthesised using chemical vapour deposition, and a phase inversion method was employed for the blending of the CNTs in the polymer composite solution for casting of the membrane. Relative to the baseline polymer, an increase of 119% in the tensile strength, 77% in the Young's modulus and 258% in the toughness is seen for a concentration of 7.5% CNTs in the polymer composite. The permeate through the membrane shows oil concentrations below the acceptable 10 mg/L limit with an excellent throughput and oil rejection of over 95%. PMID:23518875

Simplified charge separation energetics in a two-dimensional model for polymer-based photovoltaic cells.

PubMed

Sylvester-Hvid, Kristian O; Ratner, Mark A

2005-01-13

An extension of our two-dimensional working model for photovoltaic behavior in binary polymer and/or molecular photoactive blends is presented. The objective is to provide a more-realistic description of the charge generation and charge separation processes in the blend system. This is achieved by assigning an energy to each of the possible occupation states, describing the system according to a simple energy model for exciton and geminate electron-hole pair configurations. The energy model takes as primary input the ionization potential, electron affinity and optical gap of the components of the blend. The underlying photovoltaic model considers a nanoscopic subvolume of a photoactive blend and represents its p- and n-type domain morphology, in terms of a two-dimensional network of donor and acceptor sites. The nearest-neighbor hopping of charge carriers in the illuminated system is described in terms of transitions between different occupation states. The equations governing the dynamics of these states are cast into a linear master equation, which can be solved for arbitrary two-dimensional donor-acceptor networks, assuming stationary conditions. The implications of incorporating the energy model into the photovoltaic model are illustrated by simulations of the short circuit current versus thickness of the photoactive blend layer for different choices of energy parameters and donor-acceptor topology. The results suggest the existence of an optimal thickness of the photoactive film in bulk heterojunctions, based on kinetic considerations alone, and that this optimal thickness is very sensitive to the choice of energy parameters. The results also indicate space-charge limiting effects for interpenetrating donor-acceptor networks with characteristic domain sizes in the nanometer range and high driving force for the photoinduced electron transfer across the donor-acceptor internal interface.

Modeling Kepler Transit Light Curves as False Positives: Rejection of Blend Scenarios for Kepler-9, and Validation of Kepler-9 d, a Super-Earth-Size Planet in a Multiple System

NASA Technical Reports Server (NTRS)

Torres, Guillermo; Fressin, Francois; Batalha, Natalie M.; Borucki, William J.; Brown, Timothy M.; Bryson, Stephen T.; Buchhave, Lars A.; Charbonneau, David; Ciardi, David R.; Dunham, Edward W.;

Influence of beta-radiation sterilisation in properties of new chitosan/soybean protein isolate membranes for guided bone regeneration.

PubMed

Silva, R M; Elvira, C; Mano, J F; San Román, J; Reis, R L

2004-04-01

Novel chitosan (cts) and soybean protein isolate (SI) blended membranes were prepared. These membranes were produced by solvent casting. Besides combining the advantages of both materials, cts/SI membranes exhibit a biphasic structure that will eventually originate in situ porous formation, through a two-step degradation mechanism. In this particular work the effect of beta-radiation over the properties of these membranes was evaluated. beta-radiation sterilisation was performed at three different doses (25, 50 and 100 kGy) and eventual surface chemical changes were evaluated by Fourier transformed infrared--with attenuated total reflection and contact angle measurements. Moreover, eventual bulk properties changes due to beta-radiation were assessed by means of mechanical tensile tests and water uptake measurements. In general, no substantial changes were detected on the studied properties, with the exception of the surface energy that was found to be slightly increased for higher applied doses.

Inactivation of bacteria by electric current in the presence of carbon nanotubes embedded within a polymeric membrane.

PubMed

Zhu, Anna; Liu, Harris K; Long, Feng; Su, Erzheng; Klibanov, Alexander M

2015-01-01

Uniform conductive composite membranes were prepared using a phase inversion method by blending carboxyl-functionalized multi-walled carbon nanotubes (CNTs) with a polysulfone polymer. At 6 % of the embedded CNTs, the membrane pore size measured by transmission electron microscopy (TEM) was approximately 50 nm. Electric current in the presence of the composite membranes markedly inactivated the model pathogenic bacteria Escherichia coli and Staphylococcus aureus, with the extent of bacterial inactivation rising when the current was increased. Over 99.999 % inactivation of both bacteria was observed in deionized water after 40 min at 5 mA direct current (DC); importantly, no appreciable inactivation occurred in the absence of either the electric field or the CNTs within the membranes under otherwise the same conditions. A much lower, although still pronounced, inactivation was seen with alternating current (AC) in a 25 mM NaCl aqueous solution.

A search for tight hierarchical triple systems amongst the eclipsing binaries in the CoRoT fields

NASA Astrophysics Data System (ADS)

Hajdu, T.; Borkovits, T.; Forgács-Dajka, E.; Sztakovics, J.; Marschalkó, G.; Benkő, J. M.; Klagyivik, P.; Sallai, M. J.

2017-10-01

We report a comprehensive search for hierarchical triple stellar system candidates amongst eclipsing binaries (EBs) observed by the CoRoT spacecraft. We calculate and check eclipse timing variation (ETV) diagrams for almost 1500 EBs in an automated manner. We identify five relatively short period Algol systems for which our combined light-curve and complex ETV analyses (including both the light-travel time effect and short-term dynamical third-body perturbations) resulted in consistent third-body solutions. The computed periods of the outer bodies are between 82 and 272 d (with an alternative solution of 831 d for one of the targets). We find that the inner and outer orbits are near coplanar in all but one case. The dynamical masses of the outer subsystems determined from the ETV analyses are consistent with both the results of our light-curve analyses and the spectroscopic information available in the literature. One of our candidate systems exhibits outer eclipsing events as well, the locations of which are in good agreement with the ETV solution. We also report another certain triply eclipsing triple system that, however, is lacking a reliable ETV solution due to the very short time range of the data, and four new blended systems (composite light curves of two EBs each), where we cannot decide whether the components are gravitationally bounded or not. Amongst these blended systems, we identify the longest period and highest eccentricity EB in the entire CoRoT sample.

Solution processed ternary blend nano-composite charge regulation layer to enhance inverted OLED performances

NASA Astrophysics Data System (ADS)

Kaçar, Rifat; Mucur, Selin Pıravadılı; Yıldız, Fikret; Dabak, Salih; Tekin, Emine

2018-04-01

Inverted bottom-emission organic light emitting diodes (IBOLEDs) have attracted increasing attention due to their exceptional air stability and applications in active-matrix displays. For gaining high IBOLED device efficiencies, it is crucial to develop an effective strategy to make the bottom electrode easy for charge injection and transport. Charge selectivity, blocking the carrier flow towards the unfavourable side, plays an important role in determining charge carrier balance and accordingly radiative recombination efficiency. It is therefore highly desirable to functionalize an interfacial layer which will perform many different tasks simultaneously. Here, we contribute to the hole-blocking ability of the zinc oxide/polyethyleneimine (ZnO:PEI) nano-composite (NC) interlayer with the intention of increasing the OLED device efficiency. With this purpose in mind, a small amount of 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBi) was added as a hole-blocking molecule into the binary blend of ZnO and PEI solution. The device with a ternary ZnO:PEI:TPBi NC interlayer achieved a maximum current efficiency of 38.20 cd A-1 and a power efficiency of 34.29 lm W-1 with a luminance of 123 200 cd m-2, which are high performance parameters for inverted device architecture. The direct comparisons of device performances incorporating ZnO only, ZnO/PEI bilayers, and ZnO:PEI binary NC counterparts were also performed, which shed light on the origin of device performance enhancement.

Effects of iso-octane/ethanol blend ratios on the observance of negative temperature coefficient behavior within the Ignition Quality Tester

DOE PAGES

Bogin, Jr., Gregory E.; Luecke, Jon; Ratcliff, Matthew A.; ...

2016-08-21

Here, an ignition delay study investigating the reduction in low temperature heat release (LTHR) and negative temperature coefficient (NTC) region with increasing ethanol concentration in binary blends of ethanol/isooctane was conducted in the Ignition Quality Tester (IQT). The IQT is advantageous for studying multi-component fuels such as iso-octane/ethanol which are difficult to study at lower temperatures covering the NTC region in traditional systems (e.g., shock tubes, rapid compression machines, etc.). The high octane numbers and concomitant long ignition delay times of ethanol and iso-octane are ideal for study in the IQT allowing the system to reach a quasi-homogeneous mixture; allowingmore » the effect of fuel chemistry on ignition delay to be investigated with minimal impact from the fuel spray due to the relatively long ignition times. NTC behavior from iso-octane/ethanol blends was observed for the first time using an IQT. Temperature sweeps of iso-octane/ethanol volumetric blends (100/0, 90/10, 80/20, 50/50, and 0/100) were conducted from 623 to 993 K at 0.5, 1.0 and 1.5 MPa and global equivalence ratios ranging from 0.7 to 1.0. Ignition of the iso-octane/ethanol blends in the IQT was also modeled using a 0-D homogeneous batch reactor model. Significant observations include: (1) NTC behavior was observed for ethanol/ iso-octane fuel blends up to 20% ethanol. (2) Ethanol produced shorter ignition delay times than iso-octane in the high temperature region. (3) The initial increase in ethanol from 0% to 10% had a lesser impact on ignition delay than increasing ethanol from 10% to 20%. (4) The 0-D model predicts that at 0.5 and 1.0 MPa ethanol produces the shortest ignition time in the high-temperature regime, as seen experimentally.« less

Effects of iso-octane/ethanol blend ratios on the observance of negative temperature coefficient behavior within the Ignition Quality Tester

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogin, Jr., Gregory E.; Luecke, Jon; Ratcliff, Matthew A.

Here, an ignition delay study investigating the reduction in low temperature heat release (LTHR) and negative temperature coefficient (NTC) region with increasing ethanol concentration in binary blends of ethanol/isooctane was conducted in the Ignition Quality Tester (IQT). The IQT is advantageous for studying multi-component fuels such as iso-octane/ethanol which are difficult to study at lower temperatures covering the NTC region in traditional systems (e.g., shock tubes, rapid compression machines, etc.). The high octane numbers and concomitant long ignition delay times of ethanol and iso-octane are ideal for study in the IQT allowing the system to reach a quasi-homogeneous mixture; allowingmore » the effect of fuel chemistry on ignition delay to be investigated with minimal impact from the fuel spray due to the relatively long ignition times. NTC behavior from iso-octane/ethanol blends was observed for the first time using an IQT. Temperature sweeps of iso-octane/ethanol volumetric blends (100/0, 90/10, 80/20, 50/50, and 0/100) were conducted from 623 to 993 K at 0.5, 1.0 and 1.5 MPa and global equivalence ratios ranging from 0.7 to 1.0. Ignition of the iso-octane/ethanol blends in the IQT was also modeled using a 0-D homogeneous batch reactor model. Significant observations include: (1) NTC behavior was observed for ethanol/ iso-octane fuel blends up to 20% ethanol. (2) Ethanol produced shorter ignition delay times than iso-octane in the high temperature region. (3) The initial increase in ethanol from 0% to 10% had a lesser impact on ignition delay than increasing ethanol from 10% to 20%. (4) The 0-D model predicts that at 0.5 and 1.0 MPa ethanol produces the shortest ignition time in the high-temperature regime, as seen experimentally.« less

Influence of the cooling rate and the blend ratio on the physical stability of co-amorphous naproxen/indomethacin.

PubMed

Beyer, Andreas; Grohganz, Holger; Löbmann, Korbinian; Rades, Thomas; Leopold, Claudia S

2016-12-01

Co-amorphization represents a promising approach to increase the physical stability and dissolution rate of amorphous active pharmaceutical ingredients (APIs) as an alternative to polymer glass solutions. For amorphous and co-amorphous systems, it is reported that the preparation method and the blend ratio play major roles with regard to the resulting physical stability. Therefore, in the present study, co-amorphous naproxen-indomethacin (NAP/IND) was prepared by melt-quenching at three different cooling rates and at ten different NAP/IND blend ratios. The samples were analyzed using XRPD and FTIR, both directly after preparation and during storage to investigate their physical stabilities. All cooling methods led to fully amorphous samples, but with significantly different physical stabilities. Samples prepared by fast cooling had a higher degree of crystallinity after 300d of storage than samples prepared by intermediate cooling and slow cooling. Intermediate cooling was subsequently used to prepare co-amorphous NAP/IND at different blend ratios. In a previous study, it was postulated that the equimolar (0.5:0.5) co-amorphous blend of NAP/IND is most stable. However, in the present study the physically most stable blend was found for a NAP/IND ratio of 0.6:0.4, which also represents the eutectic composition of the crystalline NAP/γ-IND system. This indicates that the eutectic point may be of major importance for the stability of binary co-amorphous systems. Slight deviations from the optimal naproxen molar fraction led to significant recrystallization during storage. Either naproxen or γ-indomethacin recrystallized until a naproxen molar fraction of about 0.6 in the residual co-amorphous phase was reached again. In conclusion, the physical stability of co-amorphous NAP/IND may be significantly improved, if suitable preparation conditions and the optimal phase composition are chosen. Copyright © 2016 Elsevier B.V. All rights reserved.

Computer Simulations of Ion Transport in Polymer Electrolyte Membranes.

PubMed

Mogurampelly, Santosh; Borodin, Oleg; Ganesan, Venkat

2016-06-07

Understanding the mechanisms and optimizing ion transport in polymer membranes have been the subject of active research for more than three decades. We present an overview of the progress and challenges involved with the modeling and simulation aspects of the ion transport properties of polymer membranes. We are concerned mainly with atomistic and coarser level simulation studies and discuss some salient work in the context of pure binary and single ion conducting polymer electrolytes, polymer nanocomposites, block copolymers, and ionic liquid-based hybrid electrolytes. We conclude with an outlook highlighting future directions.

Hydrophilic nanofibers as new supports for thin film composite membranes for engineered osmosis.

PubMed

Bui, Nhu-Ngoc; McCutcheon, Jeffrey R

2013-02-05

Engineered osmosis (e.g., forward osmosis, pressure-retarded osmosis, direct osmosis) has emerged as a new platform for applications to water production, sustainable energy, and resource recovery. The lack of an adequately designed membrane has been the major challenge that hinders engineered osmosis (EO) development. In this study, nanotechnology has been integrated with membrane science to build a next generation membrane for engineered osmosis. Specifically, hydrophilic nanofiber, fabricated from different blends of polyacrylonitrile and cellulose acetate via electrospinning, was found to be an effective support for EO thin film composite membranes due to its intrinsically wetted open pore structure with superior interconnectivity. The resulting composite membrane exhibits excellent permselectivity while also showing a reduced resistance to mass transfer that commonly impacts EO processes due to its thin, highly porous nanofiber support layer. Our best membrane exhibited a two to three times enhanced water flux and 90% reduction in salt passage when compared to a standard commercial FO membrane. Furthermore, our membrane exhibited one of the lowest structural parameters reported in the open literature. These results indicate that hydrophilic nanofiber supported thin film composite membranes have the potential to be a next generation membrane for engineered osmosis.

Molecular weight dependence of LB morphology of poly(n-hexyl isocyanate) (PHIC).

PubMed

Morioka, Takako; Shibata, Osamu; Kawaguchi, Masami

2010-12-07

The morphologies of Langmuir-Blodgett (LB) films of two fractionated poly(n-hexyl isocyanate) (PHIC) and those of their binary mixtures were observed by AFM, together with those of an unfractionated PHIC. The low molecular weight PHIC formed random packing of bundles consisting of rigid rods, while the high molecular weight PHIC formed random packing of bundles consisting of hairy rods. Bundle interpenetration was observed only for the latter in the semidilute regime. In the bilayer region, the area occupied by the PHIC bundles in the upper layer was obviously smaller for the high molecular weight PHIC than for the low molecular weight PHIC, suggesting that the bundles of high molecular weight PHIC more easily interpenetrate than those of low molecular weight PHIC. For the blended films composed of both low and high molecular weight PHICs, the characteristic morphologies of the respective PHIC samples were no longer present. Moreover, the morphologies of the blended films appeared to resemble each other at any molar fraction owing to the ideal miscibility of the low molecular weight and high molecular weight PHICs. The morphologies of the blended films were also similar to that of the unfractionated PHIC film in the dilute regime. In the semidilute regime, the blended films became rounded owing to an increase in bundles interpenetration between PHICs as compared to that in the dilute regime, whereas the morphology of unfractionated PHIC films remained unchanged as compared to that in the dilute regime.

In situ monitoring of atomic layer controlled pore reduction in alumina tubular membranes using sequential surface reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berland, B.S.; Gartland, I.P.; Ott, A.W.

1998-12-01

The pore diameter in alumina tubular membranes with an initial diameter of 50 {angstrom} was systematically reduced using the atomic layer controlled deposition of Al{sub 2}O{sub 3}. The Al{sub 2}O{sub 3} was deposited using sequential exposures of Al(CH{sub 3}){sub 3} (trimethylaluminum, TMA) and H{sub 2}O in an ABAB... binary reaction sequence. The pore diameter reduction was monitored using in situ N{sub 2} and Ar conductance measurements. The conductance, C = Q/{Delta}P, was measured using a mass flow controller to define a constant gas throughput, Q, and a pair of capacitance manometers to monitor the transmembrane pressure drop, {Delta}P. Conductance measurementsmore » were periodically obtained at 298 K as a function of AB binary reaction cycles. These conductance measurements were consistent with a pore diameter reduction from 50 {angstrom} to {approximately}5--10 {angstrom} at a rate of {approximately}2.5 {angstrom} for each AB cycle. Conductance measurements were also performed during the Al{sub 2}O{sub 3} deposition at 500 K after each half-reaction in the binary reaction sequence. These in situ conductance measurements demonstrate that the pore diameters in mesoporous membranes can be reduced to molecular dimensions with atomic layer control using sequential surface reactions. Poe diameters can be tailored for specific applications by varying the number of AB cycles and changing the nature of the terminating surface functional groups.« less

Slow plastic strain rate compressive flow in binary CoAl intermetallics

NASA Technical Reports Server (NTRS)

Whittenberger, J. D.

1985-01-01

Constant-velocity elevated temperature compression tests have been conducted on a series of binary CoAl intermetallics produced by hot extrusion of blended prealloyed powders. The as-extruded materials were polycrystalline, and they retained their nominal 10-micron grain size after being tested between 1100 and 1400 K at strain rates ranging from 2 x 10 to the -4th to 2 x 10 to the -7th per sec. Significant plastic flow was obtained in all cases; while cracking was observed, much of this could be due to failure at matrix-oxide interfaces along extrusion stringers rather than to solely intergranular fracture. A maximum in flow strength occurs at an aluminum-to-cobalt ratio of 0.975, and the stress exponent appears to be constant for aluminum-to-cobalt ratios of 0.85 or more. It is likely that very aluminum-deficient materials deform by a different mechanism than do other compositions.

On the influence of tetrahedral covalent-hybridization on electronic band structure of topological insulators from first principles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, X. M.; Xu, G. Z.; Liu, E. K.

Based on first-principles calculations, we investigate the influence of tetrahedral covalent-hybridization between main-group and transition-metal atoms on the topological band structures of binary HgTe and ternary half-Heusler compounds, respectively. Results show that, for the binary HgTe, when its zinc-blend structure is artificially changed to rock-salt one, the tetrahedral covalent-hybridization will be removed and correspondingly the topologically insulating band character lost. While for the ternary half-Heusler system, the strength of covalent-hybridization can be tuned by varying both chemical compositions and atomic arrangements, and the competition between tetrahedral and octahedral covalent-hybridization has been discussed in details. As a result, we found thatmore » a proper strength of tetrahedral covalent-hybridization is probably in favor to realizing the topologically insulating state with band inversion occurring at the Γ point of the Brillouin zone.« less

Anisotropic elasticity of quasi-one-component polymer nanocomposites.

PubMed

Voudouris, Panayiotis; Choi, Jihoon; Gomopoulos, Nikos; Sainidou, Rebecca; Dong, Hongchen; Matyjaszewski, Krzysztof; Bockstaller, Michael R; Fytas, George

2011-07-26

The in-plane and out-of-plane elastic properties of thin films of "quasi-one-component" particle-brush-based nanocomposites are compared to those of "classical" binary particle-polymer nanocomposite systems with near identical overall composition using Brillouin light scattering. Whereas phonon propagation is found to be independent of the propagation direction for the binary particle/polymer blend systems, a pronounced splitting of the phonon propagation velocity along the in-plane and out-of-plane film direction is observed for particle-brush systems. The anisotropic elastic properties of quasi-one-component particle-brush systems are interpreted as a consequence of substrate-induced order formation into layer-type structures and the associated breaking of the symmetry of the film. The results highlight new opportunities to engineer quasi-one-component nanocomposites with advanced control of structural and physical property characteristics based on the assembly of particle-brush materials.

Formation of ion clusters in the phase separated structures of neutral-charged polymer blends

NASA Astrophysics Data System (ADS)

Kwon, Ha-Kyung; Olvera de La Cruz, Monica

2015-03-01

Polyelectrolyte blends, consisting of at least one charged species, are promising candidate materials for fuel cell membranes, for their mechanical stability and high selectivity for proton conduction. The phase behavior of the blends is important to understand, as this can significantly affect the performance of the device. The phase behavior is controlled by χN, the Flory-Huggins parameter multiplied by the number of mers, as well as the electrostatic interactions between the charged backbone and the counterions. It has recently been shown that local ionic correlations, incorporated via liquid state (LS) theory, enhance phase separation of the blend, even in the absence of polymer interactions. In this study, we show phase diagrams of neutral-charged polymer blends including ionic correlations via LS theory. In addition to enhanced phase separation at low χN, the blends show liquid-liquid phase separation at high electrostatic interaction strengths. Above the critical strength, the charged polymer phase separates into ion-rich and ion-poor regions, resulting in the formation of ion clusters within the charged polymer phase. This can be shown by the appearance of multiple spinodal and critical points, indicating the coexistence of several charge separated phases. This work was performed under the following financial assistance award 70NANB14H012 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD).

Reactive Nanoparticles Compatibilized Immiscible Polymer Blends: Synthesis of Reactive SiO2 with Long Poly(methyl methacrylate) Chains and the in Situ Formation of Janus SiO2 Nanoparticles Anchored Exclusively at the Interface.

PubMed

Wang, Hengti; Fu, Zhiang; Zhao, Xuewen; Li, Yongjin; Li, Jingye

2017-04-26

The exclusive location of compatibilizers at the interface of immiscible binary polymer blends to bridge the neighboring phases is the most important issue for fabricating desirable materials with synergistic properties. However, the positional stability of the compatibilizers at the interface remains a challenge in both scientific and technical points of view due to the intrinsic flexibility of compatibilizer molecules against aggressive processing conditions. Herein, taking the typical immiscible poly vinylidene fluoride (PVDF)/polylactic acid (PLLA) blend as an example, we demonstrate a novel approach, termed as the interfacial nanoparticle compatibilization (IPC) mechanism, to overcome the challenges by packing nanoparticles thermodynamically at the interface through melt reactive blending. Specifically, we have first synthesized nanosilica with both reactive epoxide groups and long poly(methyl methacrylate) (PMMA) tails, called reactive PMMA-graft-SiO 2 (Epoxy-MSiO 2 ), and then incorporated the Epoxy-MSiO 2 into the PVDF/PLLA (50/50, w/w) blends by melt blending. PLLA was in situ grafted onto SiO 2 by the reaction of the carboxylic acid groups with epoxide groups on the surface of SiO 2 . Therefore, the reacted SiO 2 particles were exclusively located at the interface by the formation of the Janus-faced silica hybrid nanoparticles (JSNp) with pregrafted PMMA tails entangled with PVDF molecular chains in the PVDF phase and the in situ grafted PLLA chains embedded in the PLLA phase. Such JSNp with a distinct hemisphere, functioning as compatibilizer, can not only suppress coalescence of PVDF domains by its steric repulsion but also enhance interfacial adhesion via the selective interactions with the corresponding miscible phase. The interfacial location of JSNp is very stable even under the severe shear field and annealing in the melt. This IPC mechanism paves a new possibility to use the various types of nanoparticles as both effective compatibilizers and functional fillers for immiscible polymer blends.

Biodegradable membrane-covered stent from chitosan-based polymers.

PubMed

Thierry, Benjamin; Merhi, Yahye; Silver, Jim; Tabrizian, Maryam

2005-12-01

Membrane-covered devices could help treat disease of the vasculature such as aneurysm, rupture, and fistulas. They are also investigated to reduce embolic complication associated with revascularization of saphenous vein graft. The aim of this study is to design a clinically applicable biodegradable membrane-covered stent based on the natural polysaccharide chitosan, which has been developed. The mechanical properties of the membrane is optimized through blending with polyethylene oxide (70:30% Wt CH:PEO). The membrane was able to sustain the mechanical deformation of the supporting self-expandable metallic stents during its deployment. The membrane was demonstrated to resist physiological transmural pressure (burst pressure resistance >500 mm Hg) and presented a high-water permeation resistance (1 mL/cm(2) min(-1) at 120 mmHg). The CH-PEO membrane showed a good hemocompatibility in an ex vivo assay. Heparin and hyaluronan surface complexation with the membrane further reduced platelet adhesion by 50.1 and 63% (p = 0.05). The ability of the membrane-covered devices to be used as a drug reservoir was investigated using the nitric oxide donor sodium nitroprusside (SNP). SNP-loaded membranes displayed significantly reduced platelet adhesion. (c) 2005 Wiley Periodicals, Inc.

Anisotropic membranes for gas separation

DOEpatents

Gollan, A.Z.

1987-07-21

A gas separation membrane has a dense separating layer about 10,000 Angstroms or less thick and a porous support layer 10 to 400 microns thick that is an integral unit with gradually and continuously decreasing pore size from the base of the support layer to the surface of the thin separating layer and is made from a casting solution comprising ethyl cellulose and ethyl cellulose-based blends, typically greater than 47.5 ethoxyl content ethyl cellulose blended with compatible second polymers, such as nitrocellulose. The polymer content of the casting solution is from about 10% to about 35% by weight of the total solution with up to about 50% of this polymer weight a compatible second polymer to the ethyl cellulose in a volatile solvent such as isopropanol, methylacetate, methanol, ethanol, and acetone. Typical nonsolvents for the casting solutions include water and formamide. The casting solution is cast in air from about zero to 10 seconds to allow the volatile solvent to evaporate and then quenched in a coagulation bath, typically water, at a temperature of 7--25 C and then air dried at ambient temperature, typically 10--30 C. 2 figs.

Physicochemical properties of macrogol ointment and emulsion ointment blend developed for regulation of water absorption.

PubMed

Noda, Yasuhiro; Watanabe, Kazuya; Sanagawa, Akimasa; Sobajima, Yu; Fujii, Satoshi

2011-10-31

Pressure ulcers can form with excess pressure and shearing stress on skin tissue. Because pressure ulcer is often accompanies by exudates, selection of appropriate topical emulsion ointment is difficult. Blended ointments consisting of emulsion base and water-soluble base are clinically used for adjustment of wound moist environment. Because regulating the amount of wound exudates can enhance treatment efficacy, two new blended ointments were developed. LY-SL blended ointment consisted of lysozyme hydrochloride water-in-oil (w/o) emulsion (LY-cream) and sulfadiazine macrogol (polyethylene glycol) ointment (SL-pasta). TR-SL blended ointment consisted of tretinoin tocoferil oil-in-water (o/w) emulsion (TR-cream) and SL-pasta (TR-SL). LY-SL and TR-SL were applied to Franz diffusion cell with cellulose membranes for the evaluation of water absorption characteristics at 32 °C. Water absorption rate constants (mg/cm(2)/min(0.5)) were 12.5, 16.3 and 34.6 for LY-cream, TR-cream and SL-pasta, respectively. Water absorption rate constants for LY-SL and TR-SL (SL-pasta 70%) exhibited intermediate values of 21.2 and 27.2, as compared to each ointment alone, respectively. Because amount of water absorbed was linearly related to square root of time, it was suggested that water-absorbable macrogol was surrounded by oily ingredients forming matrix structure. This diffusion-limited structure may regulate water absorption capacity. This is the first report of physicochemical properties of macrogol ointment and emulsion ointment blend developed for regulation of water absorption. The blended ointment can properly regulate amount of exudates in wounds and may be useful for treatment of pressure ulcers. Copyright © 2011 Elsevier B.V. All rights reserved.

Micromechanisms of Monotonic and Cyclic Subcritical Crack Growth in Advanced High Melting Point Low-Ductility Intermetallics

DTIC Science & Technology

1993-05-01

Advanced Structural Ceramics, MRS Symp. Proc., P. F. Becher et al . (eds.), MRS, Pittsburgh, PA (1986). 11) M. J. Reece, F. Guiu and M. F. R. Sammur...composites under study, listed in Table 2.1, were fabricated by phase blending -80 mesh y-TiAI (Ti-55 at.% Al , with small additions of Nb, Ta, C and 0...on phase transformations in the alloy system. In the case of the binary Nb- Al system, the peritectic reaction at 2060’C (Fig. 3.1), involving the

Thermodynamic assessment and binary nucleation modeling of Sn-seeded InGaAs nanowires

NASA Astrophysics Data System (ADS)

Ghasemi, Masoomeh; Selleby, Malin; Johansson, Jonas

2017-11-01

We have performed a thermodynamic assessment of the As-Ga-In-Sn system based on the CALculation of PHAse Diagram (CALPHAD) method. This system is part of a comprehensive thermodynamic database that we are developing for nanowire materials. Specifically, the As-Ga-In-Sn can be used in modeling the growth of GaAs, InAs, and InxGa1-xAs nanowires assisted by Sn liquid seeds. In this work, the As-Sn binary, the As-Ga-Sn, As-In-Sn, and Ga-In-Sn ternary systems have been thermodynamically assessed using the CALPHAD method. We show the relevant phase diagrams and property diagrams. They all show good agreement with experimental data. Using our optimized description we have modeled the nucleation of InxGa1-xAs in the zinc blende phase from a Sn-based quaternary liquid alloy using binary nucleation modeling. We have linked the composition of the solid nucleus to the composition of the liquid phase. Eventually, we have predicted the critical size of the nucleus that forms from InAs and GaAs pairs under various conditions. We believe that our modeling can guide future experimental realization of Sn-seeded InxGa1-xAs nanowires.

Reconciliation of Cahn-Hilliard predictions for spinodal decomposition lengthscales in polymer blends

NASA Astrophysics Data System (ADS)

Cabral, Joao

Spinodal decomposition (SD) of partially miscible polymer blends can yield well-defined nanostructures with prescribed lengthscales and connectivity, and applications ranging from membranes and scaffolds to photovoltaics. Cahn-Hilliard-Cook (CHC) theory estimates the initial, dominant SD wavenumber to be qm =√{G''/4 k } , where G'' is the second derivative of the free energy of mixing with respect to concentration and k is a structural parameter which can be computed from the segment lengths and volumes of monomer units. Tuning G'', with quench depth into the two phase region, for instance, should thus provide a facile and precise means for designing polymeric bicontinuous structures. The fulfillment of this potential rests on the thermodynamics of available polymer systems, coarsening kinetics, as well as engineering constraints. We extensively review experimental measurements of G'' in both one- and two-phase blend systems, and critically examine the accuracy of this fundamental prediction against achievements over the past 4 decades of polymer blend demixing. Despite widespread misconceptions in detecting and describing SD, we find the CHC relation to be remarkably accurate and conclude with design considerations and limitations for polymer nanostructures via SD, reflecting on John Cahn's contributions to the field.

The O-type eclipsing contact binary LY Aurigae - member of a quadruple system

NASA Astrophysics Data System (ADS)

Mayer, Pavel; Drechsel, Horst; Harmanec, Petr; Yang, Stephenson; Šlechta, Miroslav

2013-11-01

The eclipsing binary LY Aur (O9 II + O9 III) belongs to the rare class of early-type contact systems. We obtained 23 new spectra at the Ondřejov and Dominion Astrophysical Observatories, which were analysed with four older Calar Alto and one ELODIE archive spectra. A new result of this study is that the visual companion of LY Aur - the spectral lines of which are clearly seen in our spectra - is also an SB1 binary having an orbital period of 20.46d, an eccentric orbit, and a radial velocity semi-amplitude of 33 km s-1. The Hα line blend contains an emission component, which shows dependence on the orbital phase of the eclipsing system, with the strongest emission around the secondary eclipse. Revised elements of the eclipsing binary and the orbital solution of the companion binary are determined from our set of spectra and new light-curve solutions of the eclipsing pair. The mass of the primary of 25.5 M⊙ agrees well with its spectral type, whereas the secondary mass of 14 M⊙ is smaller than expected. From an O-C analysis of the minimum times of LY Aur that span more than 40 years, we found that the orbital period is decreasing, indicating the presence of interaction processes. The system is likely in a phase of non-conservative mass exchange. Based on spectral observations collected at the German-Spanish Observatory, Calar Alto, Spain; Dominion Astrophysical Observatory, Canada; Ondřejov Observatory, Czech Republic, and an archival Haute Provence Observatory ELODIE spectrum.

Comparing the antifouling effects of activated carbon and TiO2 in ultrafiltration membrane development.

PubMed

Liu, Qianyu; Huang, Shaobin; Zhang, Yongqing; Zhao, Shuaifei

2018-04-01

We use activated carbon (AC) and titanium oxide (TiO 2 ) nanomaterials as the additives to prepare four polyvinylidene fluoride (PVDF) based ultrafiltration membranes by nonsolvent induced phase separation. The surface properties (pore size, porosity, hydrophilicity and roughness) of the membranes are characterized by scanning electron microscopy, water contact angle measurement, and atomic force microscopy. The chemical properties of the membranes are evaluated by Fourier transform infrared spectroscopy with attenuated total reflection and X-ray diffraction. All these additives can improve the surface hydrophilicity and water permeation flux of the membrane. However, the addition of TiO 2 nanoparticles (20-30 nm) results in larger surface porosities and pore sizes, which causes more severe membrane fouling compared with the neat PVDF membrane. The PVDF-AC membrane exhibits excellent fouling resistance. Particularly, the irreversible fouling after blending AC into PVDF reduces dramatically from 40% to 25%. The antifouling performance of the PVDF-AC membrane may result from the improved hydrophilicity and the favorable surface and structure properties of the membrane. To the best of our knowledge, this is the first demonstration of the antifouling function of AC in membrane preparation. This study suggests that AC could be a new type of nanomaterial for developing antifouling membranes. Copyright © 2018 Elsevier Inc. All rights reserved.

Effects of adding corn oil and soy protein to corn starch on the physicochemical and digestive properties of the starch.

PubMed

Chen, Xu; He, Xiao-Wei; Zhang, Bin; Fu, Xiong; Jane, Jay-Lin; Huang, Qiang

2017-11-01

This study aimed to understand effects of adding corn oil (CO) and soy protein (SP) to corn starch on the physicochemical properties and digestive rates of annealed starch complex and mechanisms of interactions between corn starch (CS), CO and SP. Binary and ternary blends were prepared using CS mixed with CO (10%, dsb) and/or SP (10%, dsb) and incubated in a water bath at 50°C for 14h. Results showed that more agglomerates of the granules were in the ternary blends. With the addition of CO and/or SP, the CS displayed a decreased pasting temperature, an increased peak viscosity and a decreased enthalpy change of amylose-lipid complex dissociation. The CO can reinforce but SP hinder the annealing phenomenon. Results also showed that CO decreased retrogradation of CS, whereas SP increased it. The digestibility studies showed that the addition of CO and SP decreased the content of rapidly digestible starch and increased the sum of slowly digestible starch and resistant starch contents. SP displayed more impact on the digestibility of the ternary blends than CO. The physical barrier of CO, and amylose-lipid complex and protein-starch matrix can provide resistance to starch digestion. Copyright © 2017. Published by Elsevier B.V.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hickey, Robert J.; Gillard, Timothy M.; Irwin, Matthew T.

We have established the existence of a line of congruent first-order lamellar-to-disorder (LAM–DIS) transitions when appropriate amounts of poly(cyclohexylethylene) (C) and poly(ethylene) (E) homopolymers are mixed with a corresponding compositionally symmetric CE diblock copolymer. The line of congruent transitions, or the congruent isopleth, terminates at the bicontinuous microemulsion (BμE) channel, and its trajectory appears to be influenced by the critical composition of the C/E binary homopolymer blend. Blends satisfying congruency undergo a direct LAM–DIS transition without passing through a two-phase region. We present complementary optical transmission, small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and dynamic mechanical spectroscopy (DMS) resultsmore » that establish the phase behavior at constant copolymer volume fraction and varying C/E homopolymer volume ratios. Adjacent to the congruent composition at constant copolymer volume fraction, the lamellar and disordered phases are separated by two-phase coexistence windows, which converge, along with the line of congruent transitions, at an overall composition in the phase prism coincident with the BμE channel. Hexagonal and cubic (double gyroid) phases occur at higher diblock copolymer concentrations for asymmetric amounts of C and E homopolymers. These results establish a quantitative method for identifying the detailed phase behavior of ternary diblock copolymer–homopolymer blends, especially in the vicinity of the BμE.« less

Investigation of polyvinylchloride and cellulose acetate blend membranes for desalination

NASA Astrophysics Data System (ADS)

El-Gendi, Ayman; Abdallah, Heba; Amin, Ashraf; Amin, Shereen Kamel

2017-10-01

The pollution of water resources, severe climate changes, rapid population growth, increasing agricultural demands, and rapid industrialization insist the development of innovative technologies for generating potable water. Polyvinylchloride/cellulose acetate (PVC/CA) membranes were prepared using phase inversion technique for seawater reverse osmosis (SWRO). The membrane performance was investigated using Red Sea water (El-Ein El-Sokhna-Egypt). The membrane performance indicated that the prepared membranes were endowed to work under high pressure; increasing in feeding operating pressure led to increase permeate flux and rejection. Increasing feed operating pressure from zero to 40 bar led to increase in the salt rejection percent. Salt rejection percent reached to 99.99% at low feed concentration 5120 ppm and 99.95% for Red Sea water (38,528 ppm). The prepared membranes were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrophotometry, and mechanical properties. SEM, FTIR and mechanical results were used to distinguish the best membrane for desalination. According to characterization results, one prepared membrane was selected to run performance test in desalination testing unit. The membrane (M3) showed excellent performance and stability under different operating conditions and during the durability test for 36 days.

Detergent-Resistant Membrane Microdomains Facilitate Ib Oligomer Formation and Biological Activity of Clostridium perfringens Iota-Toxin

DTIC Science & Technology

2004-04-01

spore-forming bacilli such as Clostridium spiroforme (iota-like toxin), Clostridium botulinum (C2 toxin), Bacillus anthracis (lethal and edema toxins...ously (28). Goat C. spiroforme and C. perfringens type C antisera were purchased from TechLab, Inc. (Blacksburg, Va.). Mouse monoclonal antibodies...membrane preparations was specific. Previous studies showed that the binary C. spiroforme toxin shares common epitopes with iota-toxin, and antisera

Functionalized polymer nanofibre membranes for protection from chemical warfare stimulants

NASA Astrophysics Data System (ADS)

Ramaseshan, Ramakrishnan; Sundarrajan, Subramanian; Liu, Yingjun; Barhate, R. S.; Lala, Neeta L.; Ramakrishna, S.

2006-06-01

A catalyst for the detoxification of nerve agents is synthesized from β-cyclodextrin (β-CD) and o-iodosobenzoic acid (IBA). Functionalized polymer nanofibre membranes from PVC polymer are fabricated with β-CD, IBA, a blend of β-CD+IBA, and the synthesized catalyst. These functionalized nanofibres are then tested for the decontamination of paraoxon, a nerve agent stimulant, and it is observed that the stimulant gets hydrolysed. The kinetics of hydrolysis is investigated using UV spectroscopy. The rates of hydrolysis for different organophosphate hydrolyzing agents are compared. The reactivity and amount of adsorption of these catalysts are of higher capacity than the conventionally used activated charcoal. A new design for protective wear is proposed based on the functionalized nanofibre membrane.

[Study on assistant cleaning of ultrasound for the ultrafiltration membrane].

PubMed

Zhang, Guojun; Liu, Zhongzhou

2003-11-01

The effects of ultrasounds with different frequency on membrane performance were investigated in this paper. The experimental results show that there were nearly no effects of 20 W ultrasound on membrane retention coefficient, but it decreased seriously when the ultrasound power was above 30 W. On the basis of these results, low frequency ultrasound (20 W) was introduced to assist the chemical cleaning in the ultrafiltration process of wastewater from bank note printing works. The cleaning time could be shortened from 20-30 min to 5 min by the ultra-liberation and ultra-blend effects of ultrasound, therefore, the cleaning efficiency was highly improved. However, the fouling substances could not be cleaned entirely in the simple physical cleaning process by SEM analysis.

Multicomponent transport in membranes for redox flow batteries

NASA Astrophysics Data System (ADS)

Monroe, Charles

2015-03-01

Redox flow batteries (RFBs) incorporate separator membranes, which ideally prevent mixing of electrochemically active species while permitting crossover of inactive supporting ions. Understanding crossover and membrane selectivity may require multicomponent transport models that account for solute/solute interactions within the membrane, as well as solute/membrane interactions. Application of the Onsager-Stefan-Maxwell formalism allows one to account for all the dissipative phenomena that may accompany component fluxes through RFB membranes. The magnitudes of dissipative interactions (diffusional drag forces) are quantified by matching experimentally established concentration transients with theory. Such transients can be measured non-invasively using DC conductometry, but the accuracy of this method requires precise characterization of the bulk RFB electrolytes. Aqueous solutions containing both vanadyl sulfate (VOSO4) and sulfuric acid (H2SO4) are relevant to RFB technology. One of the first precise characterizations of aqueous vanadyl sulfate has been implemented and will be reported. To assess the viability of a separator for vanadium RFB applications with cell-level simulations, it is critical to understand the tendencies of various classes of membranes to absorb (uptake) active species, and to know the relative rates of active-species and supporting-electrolyte diffusion. It is also of practical interest to investigate the simultaneous diffusion of active species and supports, because interactions between solutes may ultimately affect the charge efficiency and power efficiency of the RFB system as a whole. A novel implementation of Barnes's classical model of dialysis-cell diffusion [Physics 5:1 (1934) 4-8] is developed to measure the binary diffusion coefficients and sorption equilibria for single solutes (VOSO4 or H2SO4) in porous membranes and cation-exchange membranes. With the binary diffusion and uptake measurement in hand, a computer simulation that extends the approach of Heintz, Wiedemann and Ziegler [J. Membrane Science 137:1-2 (1997) 121-132] is used to establish Onsager resistances that describe the drag forces VOSO4 and H2SO4 exert on each other as they interdiffuse. The ramifications of these interactions for different classes of membranes - and for RFB applications - will be discussed. NSF CBET-1253544.

Studies on improved integrated membrane-based chromatographic process for bioseparation

NASA Astrophysics Data System (ADS)

Xu, Yanke

To improve protein separation and purification directly from a fermentation broth, a novel membrane filtration-cum-chromatography device configuration having a relatively impermeable coated zone near the hollow fiber module outlet has been developed. The integrated membrane filtration-cum-chromatography unit packed with chromatographic beads on the shell side of the hollow fiber unit enjoys the advantages of both membrane filtration and chromatography; it allows one to load the chromatographic media directly from the fermentation broth or lysate and separate the adsorbed proteins through the subsequent elution step in a cyclic process. Interfacial polymerization was carried out to coat the bottom section of the hollow fiber membrane while leaving the rest of the hollow fiber membrane unaffected. Myoglobin (Mb), bovine serum albumin (BSA) and a-lactalbumin (a-LA) were used as model proteins in binary mixtures. Separation behaviors of binary protein mixtures were studied in devices using either an ultrafiltration (UF) membrane or a microfiltration (MF) membrane. Experimental results show that the breakthrough time and the protein loading capacities were dramatically improved after coating in both UF and MF modules. For a synthetic yeast fermentation broth feed, the Mb and a-LA elution profiles for the four consecutive cyclic runs were almost superimposable. Due to the lower transmembrane flux in this device plus the periodical washing-elution during the chromatographic separation, fouling was not a problem as it is in conventional microfiltration. A mathematical model describing the hydrodynamic and protein loading behaviors of the integrated device using UF membrane with a coated zone was developed. The simulation results for the breakthrough agree well with the experimental breakthrough curves. The optimal length of the coated zone was obtained from the simulation. A theoretical analysis of the protein mass transfer was performed using a diffusion-convection model considering the feed-side concentration polarization and the permeate-side concentration gradient formed by the adsorption. The permeate-side adsorption can enhance the observed protein transmission through the membrane considerably at low permeate flux. But the enhancement effect can be neglected at higher permeate flux when convection dominates the total mass transfer process or the proteins are very highly rejected by the membrane.

CO2 Separation Using Thermally Optimized Membranes: A Comprehensive Project Report (2000 - 2007)

DOE Office of Scientific and Technical Information (OSTI.GOV)

J.R. Klaehn; C.J. Orme; E.S. Peterson

2008-03-01

This is a complete (Fiscal Years 2000–2006) collection of the Idaho National Laboratory’s (INL) research and development contributions to the project, “CO2 Separation Using Thermally Optimized Membranes.” The INL scientific contribution to the project has varied due to the fluctuations in funding from year to year. The focus of the project was polybenzimidazole (PBI) membranes and developing PBI compounds (both substitution and blends) that provide good film formation and gas separation membranes. The underlying problem with PBI is its poor solubility in common solvents. Typically, PBI is dissolved in “aggressive” solvents, like N,N-dimethylacetamide (DMAc) and N methylpyrrolidone (NMP). The INLmore » FY-03 research was directed toward making soluble N-substituted PBI polymers, where INL was very successful. Many different types of modified PBI polymers were synthesized; however, film formation proved to be a big problem with both unsubstituted and N-substituted PBIs. Therefore, INL researchers directed their attention to using plasticizers or additives to make the membranes more stable and workable. During the course of these studies, other high-performance polymers (like polyamides and polyimides) were found to be better materials, which could be used either by themselves or blends with PBI. These alternative high-performance polymers provided the best pathway forward for soluble high-temperature polymers with good stable film formation properties. At present, the VTEC polyimides (product of RBI, Inc.) are the best film formers that exhibit high-temperature resistance. INL’s gas testing results show VTEC polyimides have very good gas selectivities for both H2/CO2 and CO2/CH4. Overall, these high-performance polymers pointed towards new research areas where INL has gained a greater understanding of polymer film formation and gas separation. These studies are making possible a direct approach to stable polymer-based high-temperature gas separation membranes. This report is separated into several sections due to the complexity of the research and the variation with the development of better high-temperature, gas separation membranes. Several fiscal years are combined because the research and development efforts within those areas crossed fiscal year boundaries.« less

CO2 Separation Using Thermally Optimized Membranes: A Comprehensive Project Report (2000 - 2007)

DOE Office of Scientific and Technical Information (OSTI.GOV)

N /A

2008-03-04

This is a complete (Fiscal Years 2000–2006) collection of the Idaho National Laboratory’s (INL) research and development contributions to the project, “CO2 Separation Using Thermally Optimized Membranes.” The INL scientific contribution to the project has varied due to the fluctuations in funding from year to year. The focus of the project was polybenzimidazole (PBI) membranes and developing PBI compounds (both substitution and blends) that provide good film formation and gas separation membranes. The underlying problem with PBI is its poor solubility in common solvents. Typically, PBI is dissolved in “aggressive” solvents, like N,N-dimethylacetamide (DMAc) and N methylpyrrolidone (NMP). The INLmore » FY-03 research was directed toward making soluble N-substituted PBI polymers, where INL was very successful. Many different types of modified PBI polymers were synthesized; however, film formation proved to be a big problem with both unsubstituted and N-substituted PBIs. Therefore, INL researchers directed their attention to using plasticizers or additives to make the membranes more stable and workable. During the course of these studies, other high-performance polymers (like polyamides and polyimides) were found to be better materials, which could be used either by themselves or blends with PBI. These alternative high-performance polymers provided the best pathway forward for soluble high-temperature polymers with good stable film formation properties. At present, the VTEC polyimides (product of RBI, Inc.) are the best film formers that exhibit high-temperature resistance. INL’s gas testing results show VTEC polyimides have very good gas selectivities for both H2/CO2 and CO2/CH4. Overall, these high-performance polymers pointed towards new research areas where INL has gained a greater understanding of polymer film formation and gas separation. These studies are making possible a direct approach to stable polymer-based high-temperature gas separation membranes. This report is separated into several sections due to the complexity of the research and the variation with the development of better high-temperature, gas separation membranes. Several fiscal years are combined because the research and development efforts within those areas crossed fiscal year boundaries.« less

Unique Pressure Dependence of the Order-Disorder Transition Temperature of a Series of PEP-PDMS Diblock Copolymers

NASA Astrophysics Data System (ADS)

Mortensen, K.; Almdal, K.; Schwahn, D.; Frielinghaus, H.

1997-03-01

Studies of the phase behavior of polymer systems has proven that the sensitivity to fluctuations is much more distinct than originally anticipated based on theoretical arguments. In blends of homo-polymers, studies have revealed that fluctuations give rise to significant re-normalized critical behavior. It has been argued that the free volume causes an entropic contribution to the Flory-Huggins interaction parameter, \\chi, and is thereby responsible for the re-normalized behavior. In block copolymers fluctuations have even more pronounced effects, as it changes the second order critical point at f=0.5 to first order and additional complex phases are stabilized. Measurements of the structure factor S(q) of PEP-PDMS diblock copolymers have revealed unique character in the phase-diagram with re-entrant ordered structure. Moreover, an unexpected singularity in the conformational compressibility, as identified from the peak-position, q, is observed. In contrary to binary polymer blends, pressure does not affect the Ginzburg number.

Effect of mineral admixtures on kinetic property and compressive strength of self Compacting Concrete

NASA Astrophysics Data System (ADS)

Jagalur Mahalingasharma, Srishaila; Prakash, Parasivamurthy; Vishwanath, K. N.; Jawali, Veena

2017-06-01

This paper presents experimental investigations made on the influence of chemical, physical, morphological and mineralogical properties of mineral admixtures such as fly ash, ground granulate blast furnace slag, metakaoline and micro silica used as a replacement of cement in self compacting concrete on workability and compressive strength. Nineteen concrete mixes were cast by replacing with cement by fly ash or ground granulated blast furnace slag as binary blend at 30%, 40%, 50% and with addition of micro silica and metakaoline at 10% as a ternary blend with fly ash, ground granulated blast furnace slag and obtained results were compare with control mix. Water powder ratio 0.3 and super plasticizer dosage 1% of cementitious material was kept constant for all the mixes. The self compacting concrete tested for slump flow, V-funnel, L-Box, J-Ring, T50, and compressive strength on concrete cube were determined at age of 3, 7, 28, 56, 90 days.

Polymorphic improvement of Stillinger-Weber potential for InGaN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Xiaowang W.; Jones, Reese E.; Chu, Kevin

A Stillinger-Weber potential is computationally very efficient for molecular dynamics simulations. Despite its simple mathematical form, the Stillinger-Weber potential can be easily parameterized to ensure that crystal structures with tetrahedral bond angles (e.g., diamond-cubic, zinc-blende, and wurtzite) are stable and have the lowest energy. As a result, the Stillinger-Weber potential has been widely used to study a variety of semiconductor elements and alloys. When studying an A-B binary system, however, the Stillinger-Weber potential is associated with two major drawbacks. First, it significantly overestimates the elastic constants of elements A and B, limiting its use for systems involving both compounds andmore » elements (e.g., an A/AB multilayer). Second, it prescribes equal energy for zinc-blende and wurtzite crystals, limiting its use for compounds with large stacking fault energies. Here in this paper, we utilize the polymorphic potential style recently implemented in LAMMPS to develop a modified Stillinger-Weber potential for InGaN that overcomes these two problems.« less

Polymorphic improvement of Stillinger-Weber potential for InGaN

NASA Astrophysics Data System (ADS)

Zhou, X. W.; Jones, R. E.; Chu, K.

2017-12-01

A Stillinger-Weber potential is computationally very efficient for molecular dynamics simulations. Despite its simple mathematical form, the Stillinger-Weber potential can be easily parameterized to ensure that crystal structures with tetrahedral bond angles (e.g., diamond-cubic, zinc-blende, and wurtzite) are stable and have the lowest energy. As a result, the Stillinger-Weber potential has been widely used to study a variety of semiconductor elements and alloys. When studying an A-B binary system, however, the Stillinger-Weber potential is associated with two major drawbacks. First, it significantly overestimates the elastic constants of elements A and B, limiting its use for systems involving both compounds and elements (e.g., an A/AB multilayer). Second, it prescribes equal energy for zinc-blende and wurtzite crystals, limiting its use for compounds with large stacking fault energies. Here, we utilize the polymorphic potential style recently implemented in LAMMPS to develop a modified Stillinger-Weber potential for InGaN that overcomes these two problems.

Probability of the Physical Association of 104 Blended Companions to Kepler Objects of Interest Using Visible and Near-infrared Adaptive Optics Photometry

NASA Astrophysics Data System (ADS)

Atkinson, Dani; Baranec, Christoph; Ziegler, Carl; Law, Nicholas; Riddle, Reed; Morton, Tim

2017-01-01

We determine probabilities of physical association for stars in blended Kepler Objects of Interest (KOIs), and find that 14.5{ % }-3.4 % +3.8 % of companions within ˜4″ are consistent with being physically unassociated with their primary. This produces a better understanding of potential false positives in the Kepler catalog and will guide models of planet formation in binary systems. Physical association is determined through two methods of calculating multi-band photometric parallax using visible and near-infrared adaptive optics observations of 84 KOI systems with 104 contaminating companions within ˜4″. We find no evidence that KOI companions with separations of less than 1″ are more likely to be physically associated than KOI companions generally. We also reinterpret transit depths for 94 planet candidates, and calculate that 2.6% ± 0.4% of transits have R> 15{R}\\oplus , which is consistent with prior modeling work.

Modeling water partition in composite gels of BSA with gelatin following high pressure treatment.

PubMed

Semasaka, Carine; Mhaske, Pranita; Buckow, Roman; Kasapis, Stefan

2018-11-01

Changes in the structural properties of hydrogels made with gelatin and bovine serum albumin mixtures were recorded following exposure to high pressure at 300 MPa for 15 min at 10 and 80 °C. Dynamic oscillation, SEM, FTIR and blending law modelling were utilised to rationalise results. Pressurization at the low temperature end yielded continuous gelatin networks supporting discontinuous BSA inclusions, whereas an inverted dispersion was formed at the high temperature end with the continuous BSA network suspending the discontinuous gelatin inclusions. Lewis and Nielsen equations followed the mechanical properties of the composites thus arguing that solvent partition between the two phases was always in favour of the polymer forming the continuous network. As far as we are aware, this is the first attempt to elucidate the solvent partition in pressurised hydrogel composites using blending law theory. Outcomes were contrasted with earlier work where binary mixtures were subjected only to thermal treatment. Copyright © 2018. Published by Elsevier Ltd.

Polymorphic improvement of Stillinger-Weber potential for InGaN

DOE PAGES

Zhou, Xiaowang W.; Jones, Reese E.; Chu, Kevin

2017-12-21

A Stillinger-Weber potential is computationally very efficient for molecular dynamics simulations. Despite its simple mathematical form, the Stillinger-Weber potential can be easily parameterized to ensure that crystal structures with tetrahedral bond angles (e.g., diamond-cubic, zinc-blende, and wurtzite) are stable and have the lowest energy. As a result, the Stillinger-Weber potential has been widely used to study a variety of semiconductor elements and alloys. When studying an A-B binary system, however, the Stillinger-Weber potential is associated with two major drawbacks. First, it significantly overestimates the elastic constants of elements A and B, limiting its use for systems involving both compounds andmore » elements (e.g., an A/AB multilayer). Second, it prescribes equal energy for zinc-blende and wurtzite crystals, limiting its use for compounds with large stacking fault energies. Here in this paper, we utilize the polymorphic potential style recently implemented in LAMMPS to develop a modified Stillinger-Weber potential for InGaN that overcomes these two problems.« less

Xenon and Other Volatile Anesthetics Change Domain Structure in Model Lipid Raft Membranes

PubMed Central

Weinrich, Michael; Worcester, David L.

2014-01-01

Inhalation anesthetics have been in clinical use for over 160 years, but the molecular mechanisms of action continue to be investigated. Direct interactions with ion channels received much attention after it was found that anesthetics do not change the structure of homogeneous model membranes. However, it was recently found that halothane, a prototypical anesthetic, changes domain structure of a binary lipid membrane. The noble gas xenon is an excellent anesthetic and provides a pivotal test of the generality of this finding, extended to ternary lipid raft mixtures. We report that xenon and conventional anesthetics change the domain equilibrium in two canonical ternary lipid raft mixtures. These findings demonstrate a membrane-mediated mechanism whereby inhalation anesthetics can affect the lipid environment of trans-membrane proteins. PMID:24299622

Confined Pattern-Directed Assembly of Polymer-Grafted Nanoparticles in a Phase Separating Blend with a Homopolymer Matrix.

PubMed

Zhang, Ren; Lee, Bongjoon; Bockstaller, Michael R; Douglas, Jack F; Stafford, Christopher M; Kumar, Sanat K; Raghavan, Dharmaraj; Karim, Alamgir

The controlled organization of nanoparticle (NP) constituents into superstructures of well-defined shape, composition and connectivity represents a continuing challenge in the development of novel hybrid materials for many technological applications. We show that the phase separation of polymer-tethered nanoparticles immersed in a chemically different polymer matrix provides an effective and scalable method for fabricating defined submicron-sized amorphous NP domains in melt polymer thin films. We investigate this phenomenon with a view towards understanding and controlling the phase separation process through directed nanoparticle assembly. In particular, we consider isothermally annealed thin films of polystyrene-grafted gold nanoparticles (AuPS) dispersed in a poly(methyl methacrylate) (PMMA) matrix. Classic binary polymer blend phase separation related morphology transitions, from discrete AuPS domains to bicontinuous to inverse domain structure with increasing nanoparticle composition is observed, yet the kinetics of the AuPS/PMMA polymer blends system exhibit unique features compared to the parent PS/PMMA homopolymer blend. We further illustrate how to pattern-align the phase-separated AuPS nanoparticle domain shape, size and location through the imposition of a simple and novel external symmetry-breaking perturbation via soft-lithography. Specifically, submicron-sized topographically patterned elastomer confinement is introduced to direct the nanoparticles into kinetically controlled long-range ordered domains, having a dense yet well-dispersed distribution of non-crystallizing nanoparticles. The simplicity, versatility and roll-to-roll adaptability of this novel method for controlled nanoparticle assembly should make it useful in creating desirable patterned nanoparticle domains for a variety of functional materials and applications.

HAT-P-68b: A Transiting Hot Jupiter Around a K5 Dwarf Star

NASA Astrophysics Data System (ADS)

Lindor, Bethlee; Hartman, Joel D.

2018-01-01

One of the main goals of the astrophysical society has been to detect sources of life outside of Earth. To aid this search, astronomers have spent the last 2 decades focused on the discovery and characterization of exoplanets. The most effective method for doing so has been transit photometry, wherein we measure the brightness of stars over periods of time. These measurements, or light curves, are later analyzed for dips in brightness caused by objects passing in front of the star. However, variations in these time series can also occur due to non-planetary systems and a meticulous process is needed to distinguish the planets from the various false positives that are detected. HATNet is one of many surveys involved in this endeavor, and in this work I analyze HAT-P-68. First, I model the system as a single star with a transiting planet and derive estimates of the stellar and planetary physical parameters. I also model HAT-P-68 as a number of a false positives such as a pair of stars in an eclipsing binary blended with a background star, and a planet-sized star orbiting a Sun-like star. In order to rule out the possibility that HAT-P-68 is a blend, I carried out a statistical blend analysis of the photometric data and find that all blend models tested can be ruled out. Thus, I conclude that HAT-P-68 is a system with a transiting hot jupiter and consider what future observations would be most promising to further characterize the system.

In vitro characterization of a novel polymeric system for preparation of amorphous solid drug dispersions.

PubMed

Mahmoudi, Zahra N; Upadhye, Sampada B; Ferrizzi, David; Rajabi-Siahboomi, Ali R

2014-07-01

Preparation of amorphous solid dispersions using polymers is a commonly used formulation strategy for enhancing the solubility of poorly water-soluble drugs. However, often a single polymer may not bring about a significant enhancement in solubility or amorphous stability of a poorly water-soluble drug. This study describes application of a unique and novel binary polymeric blend in preparation of solid dispersions. The objective of this study was to investigate amorphous solid dispersions of glipizide, a BCS class II model drug, in a binary polymeric system of polyvinyl acetate phthalate (PVAP) and hypromellose (hydroxypropyl methylcellulose, HPMC). The solid dispersions were prepared using two different solvent methods: rotary evaporation (rotavap) and fluid bed drug layering on sugar spheres. The performance and physical stability of the dispersions were evaluated with non-sink dissolution testing, powder X-ray diffraction (PXRD), and modulated differential scanning calorimetry (mDSC). PXRD analysis demonstrated an amorphous state for glipizide, and mDSC showed no evidence of phase separation. Non-sink dissolution testing in pH 7.5 phosphate buffer indicated more than twofold increase in apparent solubility of the drug with PVAP-HPMC system. The glipizide solid dispersions demonstrated a high glass transition temperature (Tg) and acceptable chemical and physical stability during the stability period irrespective of the manufacturing process. In conclusion, the polymeric blend of PVAP-HPMC offers a unique formulation approach for developing amorphous solid dispersions with the flexibility towards the use of these polymers in different ratios and combined quantities depending on drug properties.

Pore-forming activity of clostridial binary toxins.

PubMed

Knapp, O; Benz, R; Popoff, M R

2016-03-01

Clostridial binary toxins (Clostridium perfringens Iota toxin, Clostridium difficile transferase, Clostridium spiroforme toxin, Clostridium botulinum C2 toxin) as Bacillus binary toxins, including Bacillus anthracis toxins consist of two independent proteins, one being the binding component which mediates the internalization into cell of the intracellularly active component. Clostridial binary toxins induce actin cytoskeleton disorganization through mono-ADP-ribosylation of globular actin and are responsible for enteric diseases. Clostridial and Bacillus binary toxins share structurally and functionally related binding components which recognize specific cell receptors, oligomerize, form pores in endocytic vesicle membrane, and mediate the transport of the enzymatic component into the cytosol. Binding components retain the global structure of pore-forming toxins (PFTs) from the cholesterol-dependent cytotoxin family such as perfringolysin. However, their pore-forming activity notably that of clostridial binding components is more related to that of heptameric PFT family including aerolysin and C. perfringens epsilon toxin. This review focuses upon pore-forming activity of clostridial binary toxins compared to other related PFTs. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale. Copyright © 2015 Elsevier B.V. All rights reserved.

Polybenzimidazole/Mxene composite membranes for intermediate temperature polymer electrolyte membrane fuel cells.

PubMed

Fei, Mingming; Lin, Ruizhi; Deng, Yuming; Xian, Hongxi; Bian, Renji; Zhang, Xiaole; Cheng, Jigui; Xu, Chenxi; Cai, Dongyu

2018-01-19

This report demonstrated the first study on the use of a new 2D nanomaterial (Mxene) for enhancing membrane performance of intermediate temperature (>100 °C) polymer electrolyte membrane fuel cells (ITPEMFCs). In this study, a typical Ti 3 C 2 T x -MXene was synthesized and incorporated into polybenzimidazole (PBI)-based membranes by using a solution blending method. The composite membrane with 3 wt% Ti 3 C 2 T x -MXene showed the proton conductivity more than 2 times higher than that of pristine PBI membrane at the temperature range of 100 °C-170 °C, and led to substantial increase in maximum power density of fuel cells by ∼30% tested at 150 °C. The addition of Ti 3 C 2 T x -MXene also improved the mechanical properties and thermal stability of PBI membranes. At 3 wt% Ti 3 C 2 T x -MXene, the elongation at break of phosphoric acid doped PBI remained unaffected at 150 °C, and the tensile strength and Young's modulus was increased by ∼150% and ∼160%, respectively. This study pointed out promising application of MXene in ITPEMFCs.

Development of Omniphobic Desalination Membranes Using a Charged Electrospun Nanofiber Scaffold.

PubMed

Lee, Jongho; Boo, Chanhee; Ryu, Won-Hee; Taylor, André D; Elimelech, Menachem

2016-05-04

In this study, we present a facile and scalable approach to fabricate omniphobic nanofiber membranes by constructing multilevel re-entrant structures with low surface energy. We first prepared positively charged nanofiber mats by electrospinning a blend polymer-surfactant solution of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and cationic surfactant (benzyltriethylammonium). Negatively charged silica nanoparticles (SiNPs) were grafted on the positively charged electrospun nanofibers via dip-coating to achieve multilevel re-entrant structures. Grafted SiNPs were then coated with fluoroalkylsilane to lower the surface energy of the membrane. The fabricated membrane showed excellent omniphobicity, as demonstrated by its wetting resistance to various low surface tension liquids, including ethanol with a surface tension of 22.1 mN/m. As a promising application, the prepared omniphobic membrane was tested in direct contact membrane distillation to extract water from highly saline feed solutions containing low surface tension substances, mimicking emerging industrial wastewaters (e.g., from shale gas production). While a control hydrophobic PVDF-HFP nanofiber membrane failed in the desalination/separation process due to low wetting resistance, our fabricated omniphobic membrane exhibited a stable desalination performance for 8 h of operation, successfully demonstrating clean water production from the low surface tension feedwater.

Polybenzimidazole/Mxene composite membranes for intermediate temperature polymer electrolyte membrane fuel cells

NASA Astrophysics Data System (ADS)

Fei, Mingming; Lin, Ruizhi; Deng, Yuming; Xian, Hongxi; Bian, Renji; Zhang, Xiaole; Cheng, Jigui; Xu, Chenxi; Cai, Dongyu

2018-01-01

This report demonstrated the first study on the use of a new 2D nanomaterial (Mxene) for enhancing membrane performance of intermediate temperature (>100 °C) polymer electrolyte membrane fuel cells (ITPEMFCs). In this study, a typical Ti3C2T x -MXene was synthesized and incorporated into polybenzimidazole (PBI)-based membranes by using a solution blending method. The composite membrane with 3 wt% Ti3C2T x -MXene showed the proton conductivity more than 2 times higher than that of pristine PBI membrane at the temperature range of 100 °C-170 °C, and led to substantial increase in maximum power density of fuel cells by ˜30% tested at 150 °C. The addition of Ti3C2T x -MXene also improved the mechanical properties and thermal stability of PBI membranes. At 3 wt% Ti3C2T x -MXene, the elongation at break of phosphoric acid doped PBI remained unaffected at 150 °C, and the tensile strength and Young’s modulus was increased by ˜150% and ˜160%, respectively. This study pointed out promising application of MXene in ITPEMFCs.

High-Flux Carbon Molecular Sieve Membranes for Gas Separation.

PubMed

Richter, Hannes; Voss, Hartwig; Kaltenborn, Nadine; Kämnitz, Susanne; Wollbrink, Alexander; Feldhoff, Armin; Caro, Jürgen; Roitsch, Stefan; Voigt, Ingolf

2017-06-26

Carbon membranes have great potential for highly selective and cost-efficient gas separation. Carbon is chemically stable and it is relative cheap. The controlled carbonization of a polymer coating on a porous ceramic support provides a 3D carbon material with molecular sieving permeation performance. The carbonization of the polymer blend gives turbostratic carbon domains of randomly stacked together sp 2 hybridized carbon sheets as well as sp 3 hybridized amorphous carbon. In the evaluation of the carbon molecular sieve membrane, hydrogen could be separated from propane with a selectivity of 10 000 with a hydrogen permeance of 5 m 3 (STP)/(m 2 hbar). Furthermore, by a post-synthesis oxidative treatment, the permeation fluxes are increased by widening the pores, and the molecular sieve carbon membrane is transformed from a molecular sieve carbon into a selective surface flow carbon membrane with adsorption controlled performance and becomes selective for carbon dioxide. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chitosan/CNTs green nanocomposite membrane: synthesis, swelling and polyaromatic hydrocarbons removal.

PubMed

Bibi, Saira; Yasin, Tariq; Hassan, Safia; Riaz, Muhammad; Nawaz, Mohsan

2015-01-01

Carbon nanotubes (CNTs) were irradiated in air at 100 kGy under gamma radiations. The Raman spectroscopy of γ-treated CNTs showed distinctive changes in the absorption bands. The CNTs were mixed with blend of chitosan (Cs)/poly (vinyl alcohol) (PVA) and crosslinked with silane. The chemical reactions between the components affected the position and intensities of the infrared bands. Scanning electron micrograph of Cs/CNTs nanocomposite membrane showed the homogeneous dispersion of CNTs in the polymer matrix. The addition of CNTs lowered its swelling in water. Naphthalene (NAPH) was selected as a model compound and its removal was studied using HPLC technique. This membrane showed fast uptake of NAPH and 87% was removed from water within 30 min. The NAPH loaded membrane showed strong chemical interactions and cannot be desorbed. The fast uptake of PAHs and the green nature of this membrane made them suitable candidates for clean-up purposes. Copyright © 2014 Elsevier B.V. All rights reserved.

Chloroquine derivatives block the translocation pores and inhibit cellular entry of Clostridium botulinum C2 toxin and Bacillus anthracis lethal toxin.

PubMed

Kreidler, Anna-Maria; Benz, Roland; Barth, Holger

2017-03-01

The pathogenic bacteria Clostridium botulinum and Bacillus anthracis produce the binary protein toxins C2 and lethal toxin (LT), respectively. These toxins consist of a binding/transport (B 7 ) component that delivers the separate enzyme (A) component into the cytosol of target cells where it modifies its specific substrate and causes cell death. The B 7 components of C2 toxin and LT, C2IIa and PA 63 , respectively, are ring-shaped heptamers that bind to their cellular receptors and form complexes with their A components C2I and lethal factor (LF), respectively. After receptor-mediated endocytosis of the toxin complexes, C2IIa and PA 63 insert into the membranes of acidified endosomes and form trans-membrane pores through which C2I and LF translocate across endosomal membranes into the cytosol. C2IIa and PA 63 also form channels in planar bilayer membranes, and we used this approach earlier to identify chloroquine as a potent blocker of C2IIa and PA 63 pores. Here, a series of chloroquine derivatives was investigated to identify more efficient toxin inhibitors with less toxic side effects. Chloroquine, primaquine, quinacrine, and fluphenazine blocked C2IIa and PA 63 pores in planar lipid bilayers and in membranes of living epithelial cells and macrophages, thereby preventing the pH-dependent membrane transport of the A components into the cytosol and protecting cells from intoxication with C2 toxin and LT. These potent inhibitors of toxin entry underline the central role of the translocation pores for cellular uptake of binary bacterial toxins and as relevant drug targets, and might be lead compounds for novel pharmacological strategies against severe enteric diseases and anthrax.

Incorporation of Graphene-Related Carbon Nanosheets in Membrane Fabrication for Water Treatment: A Review

PubMed Central

Lawler, Jenny

2016-01-01

The minimization of the trade-off between the flux and the selectivity of membranes is a key area that researchers are continually working to optimise, particularly in the area of fabrication of novel membranes. Flux versus selectivity issues apply in many industrial applications of membranes, for example the unwanted diffusion of methanol in fuel cells, retention of valuable proteins in downstream processing of biopharmaceuticals, rejection of organic matter and micro-organisms in water treatment, or salt permeation in desalination. The incorporation of nanosheets within membrane structures can potentially lead to enhancements in such properties as the antifouling ability, hydrophilicy and permeability of membranes, with concomitant improvements in the flux/selectivity balance. Graphene nanosheets and derivatives such as graphene oxide and reduced graphene oxide have been investigated for this purpose, for example inclusion of nanosheets within the active layer of Reverse Osmosis or Nanofiltration membranes or the blending of nanosheets as fillers within Ultrafiltration membranes. This review summarizes the incorporation of graphene derivatives into polymeric membranes for water treatment with a focus on a number of industrial applications, including desalination and pharmaceutical removal, where enhancement of productivity and reduction in fouling characteristics have been afforded by appropriate incorporation of graphene derived nanosheets during membrane fabrication. PMID:27999364

Investigation of drug-excipient compatibility using rheological and thermal tools

NASA Astrophysics Data System (ADS)

Trivedi, Maitri R.

HYPOTHESIS: We plan to investigate a different approach to evaluate drug-excipient physical compatibility using rheological and thermal tools as opposed to commonly used chemical techniques in pharmaceutical industry. This approach offers practical solutions to routinely associated problems arising with API's and commonly used hydrates forms of excipients. ABSTRACT: Drug-Excipient compatibility studies are an important aspect of pre-formulation and formulation development in pharmaceutical research and development. Various approaches have been used in pharmaceutical industry including use of thermal analysis and quantitative assessment of drug-excipient mixtures after keeping the samples under stress environment depending upon the type of formulation. In an attempt to provide better understanding of such compatibility aspect of excipients with different properties of API, various rheological and thermal studies were conducted on binary mixtures of excipients which exist in different hydrates. Dibasic Calcium Phosphate (DCP, anhydrous and dihydrate forms) and Lactose (Lac, anhydrous and monohydrate) were selected with cohesive API's (Acetaminophen and Aspirin). Binary mixtures of DCP and Lac were prepared by addition of 0% w/w to 50% w/w of the API into each powder blend. Rheological and thermal aspects were considered using different approaches such as powder rheometer, rotational shear cell and traditional rheometery approaches like angle of repose (AOR), hausner's ratio (HR) and cares index (CI). Thermal analysis was conducted using modulated differential scanning calorimetry (MDSC) and thermal effusivity. The data suggested that the powder rheometer showed distinctive understanding in the flowability behavior of binary mixtures with addition of increasing proportion of API's than traditional approaches. Thermal approaches revealed the potential interaction of water of crystallization DCP-D with the API (APAP) while such interactions were absent in DCP-A, while in case of Lac-M and Lac-A, interaction with water of crystallization were not present. Binary mixtures prepared with DCP-D were better flowable while blends with DCP-A were better in stability (physical), compressibility and permeability. Similarly binary mixtures prepared with Lac-M were better flowable and stable in physical compatibility as compared to Lac-A. Lac-A were better in compressibility and permeability. Second part of these research included understanding the powder behavior from wet granulation point of view. Wet granulation includes the formation of agglomerates with powders to form granules in order to have better flowability, content uniformity and compressibility of granular mass. End point determination of powders involving change in powder energies and compressibility, permeability along with thermal analyses were conducted. The effects of water of crystallization on end point determination was studied and based on which overall effects on drug-excipient compatibility using different hydrate forms of excipients were evaluated.

[Effect of solution environments on ceramic membrane microfiltration of model system of Chinese medicines].

PubMed

Zhang, Lianjun; Lu, Jin; Le, Kang; Fu, Tingming; Guo, Liwei

2010-07-01

To investigate the effect of differents solution environments on the ceramic membrane microfiltration of model system of Chinese medicines. Taking binary system of soybean protein-berberine as the research object, flux, transmittance of berberine and traping rate of protein as indexes, different solution environment on membrane process were investigated. When the concentration of soybean protein was under 1 g x L(-1), the membrane flux was minimum with the traping of berberine decreased slightly as the concentration increased. When pH was 4, the flux was maximum with the traping rate of protein was 99%, and the transmittance of berberine reached above 60%. The efficiency of membrane separation can be improved by optimizing the solution environment of water-extraction of chinese medicines. The efficiency of membrane separation is the best when adjust the pH to the isoelectric point of proteins for the proteins as the main pollutant in aqueous solution.

Clustering procedures for the optimal selection of data sets from multiple crystals in macromolecular crystallography.

PubMed

Foadi, James; Aller, Pierre; Alguel, Yilmaz; Cameron, Alex; Axford, Danny; Owen, Robin L; Armour, Wes; Waterman, David G; Iwata, So; Evans, Gwyndaf

2013-08-01

The availability of intense microbeam macromolecular crystallography beamlines at third-generation synchrotron sources has enabled data collection and structure solution from microcrystals of <10 µm in size. The increased likelihood of severe radiation damage where microcrystals or particularly sensitive crystals are used forces crystallographers to acquire large numbers of data sets from many crystals of the same protein structure. The associated analysis and merging of multi-crystal data is currently a manual and time-consuming step. Here, a computer program, BLEND, that has been written to assist with and automate many of the steps in this process is described. It is demonstrated how BLEND has successfully been used in the solution of a novel membrane protein.

Clustering procedures for the optimal selection of data sets from multiple crystals in macromolecular crystallography

PubMed Central

Foadi, James; Aller, Pierre; Alguel, Yilmaz; Cameron, Alex; Axford, Danny; Owen, Robin L.; Armour, Wes; Waterman, David G.; Iwata, So; Evans, Gwyndaf

2013-01-01

The availability of intense microbeam macromolecular crystallography beamlines at third-generation synchrotron sources has enabled data collection and structure solution from microcrystals of <10 µm in size. The increased likelihood of severe radiation damage where microcrystals or particularly sensitive crystals are used forces crystallographers to acquire large numbers of data sets from many crystals of the same protein structure. The associated analysis and merging of multi-crystal data is currently a manual and time-consuming step. Here, a computer program, BLEND, that has been written to assist with and automate many of the steps in this process is described. It is demonstrated how BLEND has successfully been used in the solution of a novel membrane protein. PMID:23897484

Effectiveness of UV-C light assisted by mild heat on Saccharomyces cerevisiae KE 162 inactivation in carrot-orange juice blend studied by flow cytometry and transmission electron microscopy.

PubMed

García Carrillo, Mercedes; Ferrario, Mariana; Guerrero, Sandra

2018-08-01

The aim of this study was to analyze the effectiveness of UV-C light (0-10.6 kJ/m 2 ) assisted by mild heat treatment (50 °C) on the inactivation of Saccharomyces cerevisiae KE 162 in peptone water and fresh carrot-orange juice blend (pH: 3.8; 9.8°Brix; 707 NTU; absorption coefficient: 0.17 cm -1 ). Yeast induced damage by single UV-C and mild heat (H) and the combined treatment UV-C/H, was investigated by flow cytometry (FC) and transmission electron microscopy (TEM). When studying induced damage by FC, cells were labeled with fluorescein diacetate (FDA) and propidium iodide (PI) to monitor membrane integrity and esterase activity. UV-C/H provoked up to 4.7 log-reductions of S. cerevisiae; whereas, only 2.6-3.3 log-reductions were achieved by single UV-C and H treatments. FC revealed a shift with treatment time from cells with esterase activity and intact membrane to cells with permeabilized membrane. This shift was more noticeable in peptone water and UV-C/H treated juice. In the UV-C treated juice, double stained cells were detected, suggesting the possibility of being sub-lethally damaged, with compromised membrane but still metabolically active. TEM images of treated cells revealed severe damage, encompassing coagulated inner content, disorganized lumen and cell debris. FC and TEM provided additional information regarding degree and type of damage, complementing information revealed by the traditional plate count technique. Copyright © 2018 Elsevier Ltd. All rights reserved.

Efficient Preparation of Super Antifouling PVDF Ultrafiltration Membrane with One Step Fabricated Zwitterionic Surface.

PubMed

Zhao, Xinzhen; He, Chunju

2015-08-19

On the basis of the excellent fouling resistance of zwitterionic materials, the super antifouling polyvinylidene fluoride (PVDF) membrane was efficiently prepared though one-step sulfonation of PVDF and polyaniline blend membrane in situ. The self-doped sulfonated polyaniline (SPANI) was generated as a novel zwitterionic polymer to improve the antifouling property of PVDF ultrafiltration membrane used in sewage treatment. Surface attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, surface zeta potential, and water contact angle demonstrated the successful fabrication of zwitterionic interface by convenient sulfonation modification. The static adsorption fouling test showed the quantified adsorption mass of bovine serum albumin (BSA) pollutant on the PVDF/SPANI membrane surface decreases to 3(±2) μg/cm(2), and the water flux recovery ratio (FRR) values were no less than 95% for the three model pollutants of BSA, sodium alginate (SA), and humic acid (HA), which were corresponding hydrophobic, hydrophilic, and natural pollutants in sewage, respectively. This Research Article demonstrated the antifouling advantages of zwitterionic SPANI and aimed to provide a simple method for the large scale preparation of zwitterionic antifouling ultrafiltration membranes.

Rational synthesis of low-polydispersity block copolymer vesicles in concentrated solution via polymerization-induced self-assembly.

PubMed

Gonzato, Carlo; Semsarilar, Mona; Jones, Elizabeth R; Li, Feng; Krooshof, Gerard J P; Wyman, Paul; Mykhaylyk, Oleksandr O; Tuinier, Remco; Armes, Steven P

2014-08-06

Block copolymer self-assembly is normally conducted via post-polymerization processing at high dilution. In the case of block copolymer vesicles (or "polymersomes"), this approach normally leads to relatively broad size distributions, which is problematic for many potential applications. Herein we report the rational synthesis of low-polydispersity diblock copolymer vesicles in concentrated solution via polymerization-induced self-assembly using reversible addition-fragmentation chain transfer (RAFT) polymerization of benzyl methacrylate. Our strategy utilizes a binary mixture of a relatively long and a relatively short poly(methacrylic acid) stabilizer block, which become preferentially expressed at the outer and inner poly(benzyl methacrylate) membrane surface, respectively. Dynamic light scattering was utilized to construct phase diagrams to identify suitable conditions for the synthesis of relatively small, low-polydispersity vesicles. Small-angle X-ray scattering (SAXS) was used to verify that this binary mixture approach produced vesicles with significantly narrower size distributions compared to conventional vesicles prepared using a single (short) stabilizer block. Calculations performed using self-consistent mean field theory (SCMFT) account for the preferred self-assembled structures of the block copolymer binary mixtures and are in reasonable agreement with experiment. Finally, both SAXS and SCMFT indicate a significant degree of solvent plasticization for the membrane-forming poly(benzyl methacrylate) chains.

Dielectric Studies on Binary Mixtures of Diethyl Ether (DEE) in Polar Solvents

NASA Astrophysics Data System (ADS)

Pradhan, S. K.; Dash, S. K.; Swain, M. D.; Swain, B. B.

2011-11-01

Dielectric constant (ɛ) of diethylether (DEE) in binary mixtures with four polar solvents such as n-butanl, i-butanol, t-butanol and tolune has been measured at 455 kHz and at a temperature 303.15 K. The refractive indices were measured at a regulated temperature by Pulfrich refractometer at sodium D-line. The data is used to evaluate mutual correlation factor gab, excess molar polarization and excess free energy of mixing ΔGab by using Winkelmann-Quitzsch equation for binary mixtures to asses the suitability of the polar solvents as modifiers. The trend of variation for these parameters exhibit marked dependence on the nature of alcohols. Diethylether is one of the solvent extractant used for the extraction and separation of zirconium and hafnium in reactor technology. The extractant is blended with appropriate polar modifiers for greater dispersal and more rapid phase disengagement. This facilitates in the elimination of the third organo-aqueous phase containing some of the metal ions. As such the study of molecular interaction among the component molecules has been undertaken in these binary mixtures using the dielectric route. The interaction parameters such as mutual correlation factor gab is found to be less than one in all alcohols, while it is negative in toluene upto 0.7 DEE molefraction and thereafter becoming positive. The nature of variation of the excess miolar polarization ΔP and excess free energy of mixing Gab tends to support the assessment of gab to choose a suitable polar modifier.

An experimental study of the PTC properties of polymers with carbon black fillers

NASA Astrophysics Data System (ADS)

Lin, Jianlian

The Positive Temperature Coefficient (PTC) phenomenon, first discovered by Harman in 1957, is defined as the sharp increase of the electrical resistivity of the material with temperature, especially at the Curie transition temperature. Polymeric PTC materials have been widely used since 1975 as self-regulating components, over current or over heat protectors, sensors, etc. In this project a detailed study of polymeric PTC materials has been carried out. Polymeric PTC materials consist of a non-conducting polymeric phase in which conductive particles, such as CB's, are added. Previously most of the studies of the polymer matrices of PTC materials were limited to single component semi-crystalline polymers, such as HDPE, LDPE, EVA etc. In this work, the PTC effects of carbon black filled binary polymer blends, such as LDPE/EPDM, HDPD/EPDM, HDPE/EVA, etc. are mainly studied. For the LDPE/EPDM/CB system, it is found that the PTC intensity of the blends after gamma-ray irradiation increases by almost 5 orders of magnitude compared with that of irradiated LDPE/CB compound. This increase in PTC intensity is due to the greater thermal expansion coefficient of the rubber (EPDM) phase. In addition, a comparison of E-beam and gamma-ray irradiation is made and the resulting effect on the PTC properties of LDPE/EPDM/CB blends is studied in detail. It is found that with higher dose of gamma-ray, the material undergoes significant radiation damage, while irradiation with E-beam prevents radiation damage due to shorter exposure time. The influence of using treated carbon blacks on the PTC/NTC effects of the composites is also studied. The polymer blends filled with oxidized carbon black display higher PTC intensity followed by a weaker NTC effect, which is due to stronger interactions between oxidized CB's & polymer. It is concluded that strong interactions between polymers and fillers suppress the NTC effect. Finally ESR analysis is used to study the interactions between the polymer blends and fillers. It is found that relatively high structure CB's (CSF-III) have a strong interaction with the polymer blend. Based on all the work done, it is concluded that a blend of high polymer with a crystalline rubber filled with relatively high structure carbon blacks that is irradiated by E-beam will be a good polymer PTC material.

Low Voltage MEMS Digital Loudspeaker Array Based on Thin-film PZT Actuators

NASA Astrophysics Data System (ADS)

Fanget, S.; Casset, F.; Dejaeger, R.; Maire, F.; Desloges, B.; Deutzer, J.; Morisson, R.; Bohard, Y.; Laroche, B.; Escato, J.; Leclere, Q.

This paper reports on the development of a Digital Loudspeaker Array (DLA) solution based on Pb(Zr0.52,Ti0.48)O3 (PZT) thin-film actuated membranes. These membranes called speaklets are arranged in a matrix and operate in a binary manner by emitting short pulses of sound pressure. Using the principle of additivity of pressures in the air, it is possible to reconstruct audible sounds. For the first time, electromechanical and acoustic characterizations are reported on a 256-MEMS-membranes DLA. Sounds audible as far as several meters from the loudspeaker have been generated using low voltage (8 V).

Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi-Orthogonal Solvent Blends

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aguirre, Jordan C.; Hawks, Steven A.; Ferreira, Amy S.

2015-03-18

Design rules are presented for significantly expanding sequential processing (SqP) into previously inaccessible polymer:fullerene systems by tailoring binary solvent blends for fullerene deposition. Starting with a base solvent that has high fullerene solubility, 2-chlorophenol (2-CP), ellipsometry-based swelling experiments are used to investigate different co-solvents for the fullerene-casting solution. By tuning the Flory-Huggins χ parameter of the 2-CP/co-solvent blend, it is possible to optimally swell the polymer of interest for fullerene interdiffusion without dissolution of the polymer underlayer. In this way solar cell power conversion efficiencies are obtained for the PTB7 (poly[(4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)(3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl)]) and PC61BM (phenyl-C61-butyric acid methyl ester) materials combination thatmore » match those of blend-cast films. Both semicrystalline (e.g., P3HT (poly(3-hexylthiophene-2,5-diyl)) and entirely amorphous (e.g., PSDTTT (poly[(4,8-di(2-butyloxy)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)-alt-(2,5-bis(4,4'-bis(2-octyl)dithieno[3,2-b:2'3'-d]silole-2,6-diyl)thiazolo[5,4-d]thiazole)]) conjugated polymers can be processed into highly efficient photovoltaic devices using the solvent-blend SqP design rules. Grazing-incidence wide-angle x-ray diffraction experiments confirm that proper choice of the fullerene casting co-solvent yields well-ordered interdispersed bulk heterojunction (BHJ) morphologies without the need for subsequent thermal annealing or the use of trace solvent additives (e.g., diiodooctane). The results open SqP to polymer/fullerene systems that are currently incompatible with traditional methods of device fabrication, and make BHJ morphology control a more tractable problem.« less

Impact of RO-desalted water on distribution water qualities.

PubMed

Taylor, J; Dietz, J; Randall, A; Hong, S

2005-01-01

A large-scale pilot distribution study was conducted to investigate the impacts of blending different source waters on distribution water qualities, with an emphasis on metal release (i.e. corrosion). The principal source waters investigated were conventionally treated ground water (G1), surface water processed by enhanced treatment (S1), and desalted seawater by reverse osmosis membranes (RO). Due to the nature of raw water quality and associated treatment processes, G1 water had high alkalinity, while S1 and RO sources were characterized as high sulfate and high chloride waters, respectively. The blending ratio of different treated waters determined the quality of finished waters. Iron release from aged cast iron pipes increased significantly when exposed to RO and S1 waters: that is, the greater iron release was experienced with alkalinity reduced below the background of G1 water. Copper release to drinking water, however, increased with increasing alkalinity and decreasing pH. Lead release, on the other hand, increased with increasing chloride and decreasing sulfate. The effect of pH and alkalinity on lead release was not clearly observed from pilot blending study. The flat and compact corrosion scales observed for lead surface exposed to S1 water may be attributable to lead concentration less than that of RO water blends.

Improving amphiphilic polypropylenes by grafting poly(vinylpyrrolidone) and poly(ethylene glycol) methacrylate segments on a polypropylene microporous membrane

NASA Astrophysics Data System (ADS)

Chen, Huirong; Ma, Wenzhong; Xia, Yanping; Gu, Yi; Cao, Zheng; Liu, Chunlin; Yang, Haicun; Tao, Shengxi; Geng, Haoran; Tao, Guoliang; Matsuyama, Hideto

2017-10-01

An amphiphilic polypropylene-g-poly[vinylpyrrolidone-co-poly(ethylene glycol) methacrylate] (PP-g-(NVP-co-PEGMA)) modifier was prepared by melt grafting polymerization using N-vinyl pyrrolidone (NVP) as the grafting monomer and poly(ethylene glycol) (PEGMA) as the comonomer. Fourier transform infrared (FTIR) spectroscopy and elemental analysis showed that the hydrophilic branched chains (NVP-g-PEGMA) were successfully grafted to polypropylene (PP) macromolecular chains. The largest NVP grafting degree for PP-g-(NVP-co-PEGMA) (up to 20.4%) was obtained when the mass ratio of PP/NVP/PEGMA was 100/30/15. Hydrophilic PP microporous membranes were prepared by stretching cast films of PP/PP-g-(NVP-co-PEGMA) blends. The membrane thermostability (including the modifier) was better than that of the pure PP membrane with a similar surface pore structure. The porosity of the modified membranes was only slightly lower than that of the pure PP membranes. Contact angle measurements were used to examine the hydrophilicity of the membranes. The water contact angle of the membranes decreased when PP-g-(NVP-co-PEGMA) was added, and the minimum contact angle was 64.5°. Therefore, this work provides a good application for stretched hydrophilic PP membrane fabrication.

Preparation and Properties of Nano-Hydroxyapatite/Gelatin/Poly(vinyl alcohol) Composite Membrane.

PubMed

Liao, Haotian; Shi, Kun; Peng, Jinrong; Qu, Ying; Liao, Jinfeng; Qian, Zhiyong

2015-06-01

In this study, the bone-like composite membrane based on blends of gelatin (Gel), nano-hydroxyapatite (n-HA) and poly(vinyl alcohol) (PVA) was fabricated by solvent casting and evaporation methods. The effect of n-HA content and the ratio of Gel/PVA on the properties of the composite was investigated. The Gel/PVA and n-HA/Gel/PVA composite membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), water contact angle measurement and scanning electron microscopy (SEM). The mechanical properties of the composites were determined by tensile tests. The as prepared composite membranes exhibited hydrophobility, the water contact angle of composite membrane was 126.6 when its mass ratio of n-HA/Gel/PVA was 10/50/40. The tensile strength of composite membranes was greatly increased due to the introduction of n-HA, and the tensile strength was increased to 74.92 MPa when the mass ratio of n-HA/Gel/PVA was 10/50/40. SEM observation indicated that n-HA was dispersed in the membranes and a sea-island structure was formed in the n-HA/Gel/PVA composite membranes, resulting in a significant increase in tensile strength. The as-prepared n-HA/Gel/PVA composite membranes may be applied in the field of bone tissue engineering.

Nanomaterials for membrane fouling control: accomplishments and challenges.

PubMed

Yang, Qian; Mi, Baoxia

2013-11-01

We report a review of recent research efforts on incorporating nanomaterials-including metal/metal oxide nanoparticles, carbon-based nanomaterials, and polymeric nanomaterials-into/onto membranes to improve membrane antifouling properties in biomedical or potentially medical-related applications. In general, nanomaterials can be incorporated into/onto a membrane by blending them into membrane fabricating materials or by attaching them to membrane surfaces via physical or chemical approaches. Overall, the fascinating, multifaceted properties (eg, high hydrophilicity, superparamagnetic properties, antibacterial properties, amenable functionality, strong hydration capability) of nanomaterials provide numerous novel strategies and unprecedented opportunities to fully mitigate membrane fouling. However, there are still challenges in achieving a broader adoption of nanomaterials in the membrane processes used for biomedical applications. Most of these challenges arise from the concerns over their long-term antifouling performance, hemocompatibility, and toxicity toward humans. Therefore, rigorous investigation is still needed before the adoption of some of these nanomaterials in biomedical applications, especially for those nanomaterials proposed to be used in the human body or in contact with living tissue/body fluids for a long period of time. Nevertheless, it is reasonable to predict that the service lifetime of membrane-based biomedical devices and implants will be prolonged significantly with the adoption of appropriate fouling control strategies. Copyright © 2013 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Fabrication and characterization of high-efficiency double-sided blazed x-ray optics.

PubMed

Mohacsi, Istvan; Vartiainen, Ismo; Guizar-Sicairos, Manuel; Karvinen, Petri; Guzenko, Vitaliy A; Müller, Elisabeth; Kewish, Cameron M; Somogyi, Andrea; David, Christian

2016-01-15

The focusing efficiency of conventional diffractive x-ray lenses is fundamentally limited due to their symmetric binary structures and the corresponding symmetry of their focusing and defocusing diffraction orders. Fresnel zone plates with asymmetric structure profiles can break this limitation; yet existing implementations compromise either on resolution, ease of use, or stability. We present a new way for the fabrication of such blazed lenses by patterning two complementary binary Fresnel zone plates on the front and back sides of the same membrane chip to provide a compact, inherently stable, single-chip device. The presented blazed double-sided zone plates with 200 nm smallest half-pitch provide up to 54.7% focusing efficiency at 6.2 keV, which is clearly beyond the value obtainable by their binary counterparts.

Materials comprising polydienes and hydrophilic polymers and related methods

DOEpatents

Mays, Jimmy W [Knoxville, TN; Deng, Suxiang [Knoxville, TN; Mauritz, Kenneth A [Hattiesburg, MS; Hassan, Mohammad K [Hattiesburg, MS; Gido, Samuel P [Hadley, MA

2011-11-22

Materials prepared from polydienes, such as poly(cyclohexadiene), and hydrophilic polymers, such as poly(alkylene oxide), are described. Methods of making the materials and their use in fuel cell membranes, batteries, breathable chemical-biological protective materials, and templates for sol-gel polymerization are also provided. The materials can be crosslinked and sulfonated, and can include copolymers and polymer blends.

Anisotropic membranes for gas separation

DOEpatents

Gollan, Arye Z.

1987-01-01

A gas separation membrane has a dense separating layer about 10,000 Angstroms or less thick and a porous support layer 10 to 400 microns thick that is an integral unit with gradually and continuously decreasing pore size from the base of the support layer to the surface of the thin separating layer and is made from a casting solution comprising ethyl cellulose and ethyl cellulose-based blends, typically greater than 47.5 ethoxyl content ethyl cellulose blended with compatible second polymers, such as nitrocellulose. The polymer content of the casting solution is from about 10% to about 35% by weight of the total solution with up to about 50% of this polymer weight a compatible second polymer to the ethyl cellulose in a volatile solvent such as isopropanol, methylacetate, methanol, ethanol, and acetone. Typical nonsolvents for the casting solutions include water and formamide. The casting solution is cast in air from about zero to 10 seconds to allow the volatile solvent to evaporate and then quenched in a coagulation bath, typically water, at a temperature of 7.degree.-25.degree. C. and then air dried at ambient temperature, typically 10.degree.-30.degree. C.

Plasma treatment of polyethersulfone membrane for benzene removal from water by air gap membrane distillation.

PubMed

Pedram, Sara; Mortaheb, Hamid Reza; Arefi-Khonsari, Farzaneh

2018-01-01

In order to obtain a durable cost-effective membrane for membrane distillation (MD) process, flat sheet polyethersulfone (PES) membranes were modified by an atmospheric pressure nonequilibrium plasma generated using a dielectric barrier discharge in a mixture of argon and hexamethyldisiloxane as the organosilicon precursor. The surface properties of the plasma-modified membranes were characterized by water contact angle (CA), liquid entry pressure, X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. The water CA of the membrane was increased from 64° to 104° by depositing a Si(CH 3 )-rich thin layer. While the pristine PES membrane was not applicable in the MD process, the modified PES membrane could be applied for the first time in an air gap membrane distillation setup for the removal of benzene as a volatile organic compound from water. The experimental design using central composite design and response surface methodology was applied to study the effects of feed temperature, concentration, and flow rate as well as their binary interactions on the overall permeate flux and separation factor. The separation factor and permeation flux of the modified PES membrane at optimum conditions were comparable with those of commercial polytetrafluoroethylene membrane.

First-principles prediction of stabilities and instabilities of compounds and alloys in the ternary B-As-P system

NASA Astrophysics Data System (ADS)

Ektarawong, A.; Simak, S. I.; Alling, B.

2017-07-01

We examine the thermodynamic stability of compounds and alloys in the ternary B-As-P system theoretically using first-principles calculations. We demonstrate that the icosahedral B12As2 is the only stable compound in the binary B-As system, while the zinc-blende BAs is thermodynamically unstable with respect to B12As2 and the pure arsenic phase at 0 K, and increasingly so at higher temperature, suggesting that BAs may merely exist as a metastable phase. On the contrary, in the binary B-P system, both zinc-blende BP and icosahedral B12P2 are predicted to be stable. As for the binary As-P system, As1 -xPx disordered alloys are predicted at elevated temperature—for example, a disordered solid solution of up to ˜75 at.% As in black phosphorus as well as a small solubility of ˜1 at.% P in gray arsenic at T =750 K, together with the presence of miscibility gaps. The calculated large solubility of As in black phosphorus explains the experimental syntheses of black-phosphorus-type As1 -xPx alloys with tunable compositions, recently reported in the literature. We investigate the phase stabilities in the ternary B-As-P system and demonstrate a high tendency for a formation of alloys in the icosahedral B12(As1 -xPx )2 structure by intermixing of As and P atoms at the diatomic chain sites. The phase diagram displays noticeable mutual solubility of the icosahedral subpnictides in each other even at room temperature as well as a closure of a pseudobinary miscibility gap around 900 K. As for pseudobinary BAs1 -xPx alloys, only a tiny amount of BAs is predicted to be able to dissolve in BP to form the BAs1 -xPx disordered alloys at elevated temperature. For example, less than 5% of BAs can dissolve in BP at T =1000 K. The small solubility limit of BAs in BP is attributed to the thermodynamic instability of BAs with respect to B12As2 and As.

Facile Fabrication of Composite Membranes with Dual Thermo- and pH-Responsive Characteristics.

PubMed

Ma, Bing; Ju, Xiao-Jie; Luo, Feng; Liu, Yu-Qiong; Wang, Yuan; Liu, Zhuang; Wang, Wei; Xie, Rui; Chu, Liang-Yin

2017-04-26

Facile fabrication of novel functional membranes with excellent dual thermo- and pH-responsive characteristics has been achieved by simply designing dual-layer composite membranes. pH-Responsive poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymers and polystyrene blended with thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) nanogels are respectively used to construct the top layer and bottom layer of composite membranes. The stretching/coiling conformation changes of the P4VP chains around the pK a (∼3.5-4.5) provide the composite membranes with extraordinary pH-responsive characteristics, and the volume phase transitions of PNIPAM nanogels at the pore/matrix interfaces in the bottom layer around the volume phase transition temperature (VPTT, ∼33 °C) provide the composite membranes with great thermoresponsive characteristics. The microstructures, permeability performances, and dual stimuli-responsive characteristics can be well tuned by adjusting the content of PNIPAM nanogels and the thickness of the PS-b-P4VP top layer. The water fluxes of the composite membranes can be changed in order of magnitude by changing the environment temperature and pH, and the dual thermo- and pH-responsive permeation performances of the composite membranes are satisfactorily reversible and reproducible. The membrane fabrication strategy in this work provides valuable guidance for further development of dual stimuli-responsive membranes or even multi stimuli-responsive membranes.

pH-dependent Differential Scanning Calorimetry and Dynamic Light Scattering Studies of 21:0 PC and 18:0 PS Lipid Binary System

NASA Astrophysics Data System (ADS)

Ali, Rejwan

2010-03-01

Large unilamallar vesicle has been a model system to study many membrane functions. High Tg lipid systems offer many potential biomedical applications in lipid-based delivery applications. While the optimized vesicle functionalities are achieved by Polyethylene Glycol (PEG) polymer, modified PEG and other functional molecule incorporation, however, the host binary lipid system plays the pivotal role in pH-dependent phase transition based lipid vehicular methods. We have investigated a lipid binary system composed of 21:0 PC (1,2-dihenarachidoyl-sn-glycero-3-phosphocholine) and 18:0 PS(1,2-distearoyl-sn-glycero-3-phospho-L-serine). Preliminary studies implementing differential scanning calorimetry shows pH plays key role in temperature shift and thermotropic phase behavior of the binary system. While dynamic light scattering study shows lipid vesicle size is almost independent of pH changes. We will also present pH-dependent thermodynamic parameters to correlate underlying molecular mechanism in relevant pH-range.

Surface modification of commercial seawater reverse osmosis membranes by grafting of hydrophilic monomer blended with carboxylated multiwalled carbon nanotubes

NASA Astrophysics Data System (ADS)

Vatanpour, Vahid; Zoqi, Naser

2017-02-01

In this study, modification of commercial seawater reverse osmosis membranes was carried out with simultaneous use of surface grafting and nanoparticle incorporation. Membrane grafting with a hydrophilic acrylic acid monomer and thermal initiator was used to increase membrane surface hydrophilicity. The used nanomaterial was carboxylated multiwalled carbon nanotubes (MWCNTs), which were dispersed in the grafting solution and deposited on membrane surface to reduce fouling by creating polymer brushes and hydrodynamic resistance. Effectiveness of the grafting process (formation of graft layer on membrane surface) was proved by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses. Increase of membrane surface hydrophilicity was approved with contact angle test. First, the grafting was performed on the membrane surfaces with different monomer concentrations, various contact times and several membrane curing times (three variables for optimization). The modified membranes were tested by a cross-flow setup using saline solution for permeability and rejection tests, and bovine serum albumin (BSA) solution for fouling test. The results showed that the modified membranes with 0.75 M of monomer, 3 min contact time and 80 min curing time in an oven at 50 °C presented the highest flux and lowest rejection decline related to the commercial reverse osmosis membrane. In the next step, the optimum grafting condition was selected and the nanotubes with different weight percentages were dispersed in the acrylic acid monomer solution. The membrane containing 0.25 wt% COOH-MWCNTs showed the highest fouling resistance.

Metal Composition and Polyethylenimine Doping Capacity Effects on Semiconducting Metal Oxide-Polymer Blend Charge Transport.

PubMed

Huang, Wei; Guo, Peijun; Zeng, Li; Li, Ran; Wang, Binghao; Wang, Gang; Zhang, Xinan; Chang, Robert P H; Yu, Junsheng; Bedzyk, Michael J; Marks, Tobin J; Facchetti, Antonio

2018-04-25

Charge transport and film microstructure evolution are investigated in a series of polyethylenimine (PEI)-doped (0.0-6.0 wt%) amorphous metal oxide (MO) semiconductor thin film blends. Here, PEI doping generality is broadened from binary In 2 O 3 to ternary (e.g., In+Zn in IZO, In+Ga in IGO) and quaternary (e.g., In+Zn+Ga in IGZO) systems, demonstrating the universality of this approach for polymer electron doping of MO matrices. Systematic comparison of the effects of various metal ions on the electronic transport and film microstructure of these blends are investigated by combined thin-film transistor (TFT) response, AFM, XPS, XRD, X-ray reflectivity, and cross-sectional TEM. Morphological analysis reveals that layered MO film microstructures predominate in PEI-In 2 O 3 , but become less distinct in IGO and are not detectable in IZO and IGZO. TFT charge transport measurements indicate a general coincidence of a peak in carrier mobility (μ peak ) and overall TFT performance at optimal PEI doping concentrations. Optimal PEI loadings that yield μ peak values depend not only on the MO elemental composition but also, equally important, on the metal atomic ratios. By investigating the relationship between the MO energy levels and PEI doping by UPS, it is concluded that the efficiency of PEI electron-donation is highly dependent on the metal oxide matrix work function in cases where film morphology is optimal, as in the IGO compositions. The results of this investigation demonstrate the broad generality and efficacy of PEI electron doping applied to electronically functional metal oxide systems and that the resulting film microstructure, morphology, and energy level modifications are all vital to understanding charge transport in these amorphous oxide blends.

Removal of bisphenol A by adsorption mechanism using PES-SiO2 composite membranes.

PubMed

Muhamad, Mimi Suliza; Salim, Mohd Razman; Lau, Woei Jye; Hadibarata, Tony; Yusop, Zulkifli

2016-08-01

Polyethersulphone (PES) membranes blended with silicon dioxide (SiO2) nanoparticles were prepared via a dry-jet wet spinning technique for the removal of bisphenol A (BPA) by adsorption mechanism. The morphology of SiO2 nanoparticles was analysed using a transmission electron microscopy and particle size distribution was also analysed. The prepared membranes were characterized by several techniques including field emission scanning electron microscopy, Fourier transform infrared spectroscopy and water contact angle. The adsorption mechanism of membrane towards BPA was evaluated by batch experiments and kinetic model. The influence of natural organic matter (NOM) in feed water on membrane BPA removal was also studied by filtration experiments. Results showed that BPA adsorption capacity as high as 53 µg/g could be achieved by the PES membrane incorporated with 2 wt% SiO2 in which the adsorption mechanism was in accordance with the pseudo-second-order kinetic model. The intraparticles diffusion model suggested that the rate limiting factor of membrane adsorption mechanism is governed by the diffusion of BPA into the membrane pores. The presence of 10 ppm NOM has reported to negatively reduce BPA removal by 24%, as it tended to compete with BPA for membrane adsorption. This work has demonstrated that PES-SiO2 membrane has the potential to eliminate trace amount of BPA from water source containing NOM.

Surface zwitterionicalization of poly(vinylidene fluoride) membranes from the entrapped reactive core-shell silica nanoparticles.

PubMed

Zhu, Li-Jing; Zhu, Li-Ping; Zhang, Pei-Bin; Zhu, Bao-Ku; Xu, You-Yi

2016-04-15

We demonstrate the preparation and properties of poly(vinylidene fluoride) (PVDF) filtration membranes modified via surface zwitterionicalization mediated by reactive core-shell silica nanoparticles (SiO2 NPs). The organic/inorganic hybrid SiO2 NPs grafted with poly(methyl meth acrylate)-block-poly(2-dimethylaminoethyl methacrylate) copolymer (PMMA-b-PDMAEMA) shell were prepared by surface-initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization and then used as a membrane-making additive of PVDF membranes. The PDMAEMA exposed on membrane surface and pore walls were quaternized into zwitterionic poly(sulfobetaine methacrylate) (PSBMA) using 1,3-propane sultone (1,3-PS) as the quaternization agent. The membrane surface chemistry and morphology were analyzed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. The hydrophilicity, permeability and antifouling ability of the investigated membranes were evaluated in detail. It was found that the PSBMA chains brought highly-hydrophilic and strong fouling resistant characteristics to PVDF membranes due to the powerful hydration of zwitterionic surface. The SiO2 cores and PMMA chains in the hybrid NPs play a role of anchors for the linking of PSBMA chains to membrane surface. Compared to the traditional strategies for membrane hydrophilic modification, the developed method in this work combined the advantages of both blending and surface reaction. Copyright © 2016 Elsevier Inc. All rights reserved.

Improved surface hydrophilicity and antifouling property of polysulfone ultrafiltration membrane with poly(ethylene glycol) methyl ether methacrylate grafted graphene oxide nanofillers

NASA Astrophysics Data System (ADS)

Wang, Haidong; Lu, Xiaofei; Lu, Xinglin; Wang, Zhenghui; Ma, Jun; Wang, Panpan

2017-12-01

In this study, the GO-g-P(PEGMA) nanoplates were first synthesized by grafting hydrophilic poly (poly (ethylene glycol) methyl ether methacrylate) via surface-initiated atom transfer radical polymerization (SI-ATRP) method. A novel polysulfone (PSF) nanocomposite membrane using GO-g-P(PEGMA) nanoplates as nanofillers was fabricated. FTIR, TGA, 1H NMR, GPC and TEM were applied to verify the successful synthesis of the prepared nanoplates, while SEM, AFM, XPS, contact angle goniometry and filtration experiments were used to characterize the fabricated nanocomposite membranes. It was found that the new prepared nanofillers were well dispersed in organic PSF matrix, and the PSF/GO-g-P(PEGMA) nanocomposite membrane showed significant improvements in water flux and flux recovery rate. Based on the results of resistance-in-series model, the nanocomposite membrane exhibited superior resistance to the irreversible fouling. The excellent filtration and antifouling performance are attributed to the segregation of GO-g-P(PEMGA) nanofillers toward the membrane surface and the pore walls. Notably, the blended nanofillers appeared a stable retention in/on nanocomposite membrane after 30 days of washing time. The demonstrated method of synthesis GO-g-P(PEGMA) in this study can also be extended to preparation of other nanocomposite membrane in future.

Polymeric membranes modulate human keratinocyte differentiation in specific epidermal layers.

PubMed

Salerno, Simona; Morelli, Sabrina; Giordano, Francesca; Gordano, Amalia; Bartolo, Loredana De

2016-10-01

In vitro models of human bioengineered skin substitutes are an alternative to animal experimentation for testing the effects and toxicity of drugs, cosmetics and pollutants. For the first time specific and distinct human epidermal strata were engineered by using membranes and keratinocytes. To this purpose, biodegradable membranes of chitosan (CHT), polycaprolactone (PCL) and a polymeric blend of CHT-PCL were prepared by phase-inversion technique and characterized in order to evaluate their morphological, physico-chemical and mechanical properties. The capability of membranes to modulate keratinocyte differentiation inducing specific interactions in epidermal membrane systems was investigated. The overall results demonstrated that the membrane properties strongly influence the cell morpho-functional behaviour of human keratinocytes, modulating their terminal differentiation, with the creation of specific epidermal strata or a fully proliferative epidermal multilayer system. In particular, human keratinocytes adhered on CHT and CHT-PCL membranes, forming the structure of the epidermal top layers, such as the corneum and granulosum strata, characterized by withdrawal or reduction from the cell cycle and cell proliferation. On the PCL membrane, keratinocytes developed an epidermal basal lamina, with high proliferating cells that stratified and migrated over time to form a complete differentiating epidermal multilayer system. Copyright © 2016 Elsevier B.V. All rights reserved.

Facile fabrication of aloe vera containing PCL nanofibers for barrier membrane application.

PubMed

Carter, Princeton; Rahman, Shekh M; Bhattarai, Narayan

2016-01-01

Guided tissue regeneration (GTR) is a widely used method in dental surgical procedures that utilizes a barrier membrane to exclude migration of epithelium and ensure repopulation of periodontal ligament cells at the sites having insufficient gingiva. Commercial GTR membranes are typically composed of synthetic polymers that have had mild clinical success mostly because of their lack of proper bioactivity and appropriate degradation profile. In this study, a natural polymer, aloe vera was blended with polycaprolactone (PCL) to create nanofibrous GTR membranes by electrospinning. Aloe vera has proven anti-inflammatory properties and enhances the regeneration of periodontium tissues. PCL, a synthetic polymer, is well known to produce miscible polyblends nanofibers with natural polymers. Nanofibrous membranes with varying composition of PCL to aloe vera were fabricated, and several physicochemical and biological properties, such as fiber morphology, wettability, chemical structure, mechanical strength, and cellular compatibility of the membranes were analyzed. PCL/aloe vera membranes with ratios from 100/00 to 70/30 showed good uniformity in fiber morphology and suitable mechanical properties, and retained the integrity of their fibrous structure in aqueous solutions. Experimental results, using cell viability assay and cell attachment observation, showed that the nanofibrous membranes support 3T3 cell viability and could be a potential candidate for GTR therapy.

A review on bisphenol A occurrences, health effects and treatment process via membrane technology for drinking water.

PubMed

Muhamad, Mimi Suliza; Salim, Mohd Razman; Lau, Woei Jye; Yusop, Zulkifli

2016-06-01

Massive utilization of bisphenol A (BPA) in the industrial production of polycarbonate plastics has led to the occurrence of this compound (at μg/L to ng/L level) in the water treatment plant. Nowadays, the presence of BPA in drinking water sources is a major concern among society because BPA is one of the endocrine disruption compounds (EDCs) that can cause hazard to human health even at extremely low concentration level. Parallel to these issues, membrane technology has emerged as the most feasible treatment process to eliminate this recalcitrant contaminant via physical separation mechanism. This paper reviews the occurrences and effects of BPA toward living organisms as well as the application of membrane technology for their removal in water treatment plant. The potential applications of using polymeric membranes for BPA removal are also discussed. Literature revealed that modifying membrane surface using blending approach is the simple yet effective method to improve membrane properties with respect to BPA removal without compromising water permeability. The regeneration process helps in maintaining the performances of membrane at desired level. The application of large-scale membrane process in treatment plant shows the feasibility of the technology for removing BPA and possible future prospect in water treatment process.

Electric field-induced reorganization of two-component supported bilayer membranes

PubMed Central

Groves, Jay T.; Boxer, Steven G.; McConnell, Harden M.

1997-01-01

Application of electric fields tangent to the plane of a confined patch of fluid bilayer membrane can create lateral concentration gradients of the lipids. A thermodynamic model of this steady-state behavior is developed for binary systems and tested with experiments in supported lipid bilayers. The model uses Flory’s approximation for the entropy of mixing and allows for effects arising when the components have different molecular areas. In the special case of equal area molecules the concentration gradient reduces to a Fermi–Dirac distribution. The theory is extended to include effects from charged molecules in the membrane. Calculations show that surface charge on the supporting substrate substantially screens electrostatic interactions within the membrane. It also is shown that concentration profiles can be affected by other intermolecular interactions such as clustering. Qualitative agreement with this prediction is provided by comparing phosphatidylserine- and cardiolipin-containing membranes. PMID:9391034

Electric field-induced reorganization of two-component supported bilayer membranes.

PubMed

Groves, J T; Boxer, S G; McConnell, H M

1997-12-09

Application of electric fields tangent to the plane of a confined patch of fluid bilayer membrane can create lateral concentration gradients of the lipids. A thermodynamic model of this steady-state behavior is developed for binary systems and tested with experiments in supported lipid bilayers. The model uses Flory's approximation for the entropy of mixing and allows for effects arising when the components have different molecular areas. In the special case of equal area molecules the concentration gradient reduces to a Fermi-Dirac distribution. The theory is extended to include effects from charged molecules in the membrane. Calculations show that surface charge on the supporting substrate substantially screens electrostatic interactions within the membrane. It also is shown that concentration profiles can be affected by other intermolecular interactions such as clustering. Qualitative agreement with this prediction is provided by comparing phosphatidylserine- and cardiolipin-containing membranes.

From the speed of sound to the speed of light: Ultrasonic Cherenkov refractometry

NASA Astrophysics Data System (ADS)

Hallewell, G. D.

2017-12-01

Despite its success in the SLD CRID at the SLAC Linear Collider, ultrasonic measurement of Cherenkov radiator refractive index has been less fully exploited in more recent Cherenkov detectors employing gaseous radiators. This is surprising, since it is ideally suited to monitoring hydrostatic variations in refractive index as well as its evolution during the replacement of a light radiator passivation gas (e.g. N2, CO2) with a heavier fluorocarbon (e.g. C4F10[CF4]; mol. wt. 188[88]). The technique exploits the dependence of sound velocity on the molar concentrations of the two components at known temperature and pressure. The SLD barrel CRID used an 87%C5F12/13%N2 blend, mixed before injection into the radiator vessel: blend control based on ultrasonic mixture analysis maintained the β=1 Cherenkov ring angle to a long term variation better than ±0.3%, with refractivity monitored ultrasonically at multiple points within the radiator vessel. Recent advances using microcontroller-based electronics have led to ultrasonic instruments capable of simultaneously measuring gas flow and binary mixture composition in the fluorocarbon evaporative cooling systems of the ATLAS Inner Detector. Sound transit times are measured with multi-MHz transit time clocks in opposite directions in flowing gas for simultaneous measurement of flow rate and sound velocity. Gas composition is evaluated in real-time by comparison with a sound velocity/composition database. Such instruments could be incorporated into new and upgraded gas Cherenkov detectors for radiator gas mixture (and corresponding refractive index) measurement to a precision better than 10-3. They have other applications in binary gas analysis - including in Xenon-based anaesthesia. These possibilities are discussed.

SIMULTANEOUS MULTIWAVELENGTH OBSERVATIONS OF MAGNETIC ACTIVITY IN ULTRACOOL DWARFS. IV. THE ACTIVE, YOUNG BINARY NLTT 33370 AB (= 2MASS J13142039+1320011)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, P. K. G.; Berger, E.; Irwin, J.

We present multi-epoch simultaneous radio, optical, Hα, UV, and X-ray observations of the active, young, low-mass binary NLTT 33370 AB (blended spectral type M7e). This system is remarkable for its extreme levels of magnetic activity: it is the most radio-luminous ultracool dwarf (UCD) known, and here we show that it is also one of the most X-ray luminous UCDs known. We detect the system in all bands and find a complex phenomenology of both flaring and periodic variability. Analysis of the optical light curve reveals the simultaneous presence of two periodicities, 3.7859 ± 0.0001 and 3.7130 ± 0.0002 hr. While these differmore » by only ∼2%, studies of differential rotation in the UCD regime suggest that it cannot be responsible for the two signals. The system's radio emission consists of at least three components: rapid 100% polarized flares, bright emission modulating periodically in phase with the optical emission, and an additional periodic component that appears only in the 2013 observational campaign. We interpret the last of these as a gyrosynchrotron feature associated with large-scale magnetic fields and a cool, equatorial plasma torus. However, the persistent rapid flares at all rotational phases imply that small-scale magnetic loops are also present and reconnect nearly continuously. We present a spectral energy distribution of the blended system spanning more than 9 orders of magnitude in wavelength. The significant magnetism present in NLTT 33370 AB will affect its fundamental parameters, with the components' radii and temperatures potentially altered by ∼+20% and ∼–10%, respectively. Finally, we suggest spatially resolved observations that could clarify many aspects of this system's nature.« less

Enhanced Flux and Electrochemical Cleaning of Silicate Scaling on Carbon Nanotube-Coated Membrane Distillation Membranes Treating Geothermal Brines.

PubMed

Tang, Li; Iddya, Arpita; Zhu, Xiaobo; Dudchenko, Alexander V; Duan, Wenyan; Turchi, Craig; Vanneste, Johann; Cath, Tzahi Y; Jassby, David

2017-11-08

The desalination of inland brackish groundwater offers the opportunity to provide potable drinking water to residents and industrial cooling water to industries located in arid regions. Geothermal brines are used to generate electricity, but often contain high concentrations of dissolved salt. Here, we demonstrate how the residual heat left in spent geothermal brines can be used to drive a membrane distillation (MD) process and recover desalinated water. Porous polypropylene membranes were coated with a carbon nanotube (CNT)/poly(vinyl alcohol) layer, resulting in composite membranes having a binary structure that combines the hydrophobic properties critical for MD with the hydrophilic and conductive properties of the CNTs. We demonstrate that the addition of the CNT layer increases membrane flux due to enhanced heat transport from the bulk feed to the membrane surface, a result of CNT's high thermal transport properties. Furthermore, we show how hydroxide ion generation, driven by water electrolysis on the electrically conducting membrane surface, can be used to efficiently dissolve silicate scaling that developed during the process of desalinating the geothermal brine, negating the need for chemical cleaning.

Polarized Cell Division of Chlamydia trachomatis

PubMed Central

Abdelrahman, Yasser; Ouellette, Scot P.; Belland, Robert J.; Cox, John V.

2016-01-01

Bacterial cell division predominantly occurs by a highly conserved process, termed binary fission, that requires the bacterial homologue of tubulin, FtsZ. Other mechanisms of bacterial cell division that are independent of FtsZ are rare. Although the obligate intracellular human pathogen Chlamydia trachomatis, the leading bacterial cause of sexually transmitted infections and trachoma, lacks FtsZ, it has been assumed to divide by binary fission. We show here that Chlamydia divides by a polarized cell division process similar to the budding process of a subset of the Planctomycetes that also lack FtsZ. Prior to cell division, the major outer-membrane protein of Chlamydia is restricted to one pole of the cell, and the nascent daughter cell emerges from this pole by an asymmetric expansion of the membrane. Components of the chlamydial cell division machinery accumulate at the site of polar growth prior to the initiation of asymmetric membrane expansion and inhibitors that disrupt the polarity of C. trachomatis prevent cell division. The polarized cell division of C. trachomatis is the result of the unipolar growth and FtsZ-independent fission of this coccoid organism. This mechanism of cell division has not been documented in other human bacterial pathogens suggesting the potential for developing Chlamydia-specific therapeutic treatments. PMID:27505160

Binary Synergy Strengthening and Toughening of Bio-Inspired Nacre-like Graphene Oxide/Sodium Alginate Composite Paper.

PubMed

Chen, Ke; Shi, Bin; Yue, Yonghai; Qi, Juanjuan; Guo, Lin

2015-08-25

A crucial requirement for most engineering materials is the excellent balance of strength and toughness. By mimicking the hybrid hierarchical structure in nacre, a kind of nacre-like paper based on binary hybrid graphene oxide (GO)/sodium alginate (SA) building blocks has been successfully fabricated. Systematic evaluation for the mechanical property in different (dry/wet) environment/after thermal annealing shows a perfect combination of high strength and toughness. Both of the parameters are nearly many-times higher than those of similar materials because of the synergistic strengthening/toughening enhancement from the binary GO/SA hybrids. The successful fabrication route offers an excellent approach to design advanced strong integrated nacre-like composite materials, which can be applied in tissue engineering, protection, aerospace, and permeable membranes for separation and delivery.

Separation of copper ions from iron ions using PVA-g-(acrylic acid/N-vinyl imidazole) membranes prepared by radiation-induced grafting.

PubMed

Ajji, Zaki; Ali, Ali M

2010-01-15

Acrylic acid (AAc), N-vinyl imidazole (Azol) and their binary mixtures were graft copolymerized onto poly(vinyl alcohol) membranes using gamma irradiation. The ability of the grafted membranes to separate Cu ions from Fe ions was investigated with respect to the grafting yield and the pH of the feed solution. The data showed that the diffusion of copper ions from the feed compartment to the receiver compartment depends on the grafting yield of the membranes and the pH of the feed solution. To the contrary, iron ions did not diffuse through the membranes of all grafting yields. However, a limited amount of iron ions diffused in strong acidic medium. This study shows that the prepared membranes could be considered for the separation of copper ions from iron ions. The temperature of thermal decomposition of pure PVA-g-AAc/Azol membrane, PVA-g-AAc/Azol membrane containing copper ions, and PVA-g-AAc/Azol membrane containing iron ions were determined using TGA analyzer. It was shown that the presence of Cu and Fe ions increases the decomposition temperature, and the membranes bonded with iron ions are more stable than those containing copper ions.

Metal/ceramic composites with high hydrogen permeability

DOEpatents

Dorris, Stephen E.; Lee, Tae H.; Balachandran, Uthamalingam

2003-05-27

A membrane for separating hydrogen from fluids is provided comprising a sintered homogenous mixture of a ceramic composition and a metal. The metal may be palladium, niobium, tantalum, vanadium, or zirconium or a binary mixture of palladium with another metal such as niobium, silver, tantalum, vanadium, or zirconium.

Dielectric, ferroelectric, and thermodynamic properties of silicone oil modified PVDF films for energy storage application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Bingcheng; Wang, Xiaohui, E-mail: wxh@tsinghua.edu.cn, E-mail: llt-dms@mail.tsinghua.edu.cn; Li, Longtu, E-mail: wxh@tsinghua.edu.cn, E-mail: llt-dms@mail.tsinghua.edu.cn

Silicone oil modified poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) films were fabricated by the blending, casting, and hot-molding methods. The dielectric constant was increased for the 7.4 wt. % and 17.0 wt. % silicone oil modified P(VDF-HFP) films, while the dielectric loss for all blend films are decreased. D-E loops of 7.4 wt. % and 17.0 wt. % silicone oil modified P(VDF-HFP) films become slimmer than the pristine P(VDF-HFP) films. The maximum discharged energy density of 10.3 J/cm{sup 3} was obtained in 7.4 wt. % silicone oil modified P(VDF-HFP) films at the external electric field of 398 kV/mm. The Gibbs energy, miscibility, and phase behavior of binary mixture of P(VDF-HFP) silicone oil were investigated usingmore » molecular simulations and the extended Flory–Huggins model revealing favorable interactions and compatibility between P(VDF-HFP) and silicone oil.« less

Quantification of extra virgin olive oil in dressing and edible oil blends using the representative TMS-4,4'-desmethylsterols gas-chromatographic-normalized fingerprint.

PubMed

Pérez-Castaño, Estefanía; Sánchez-Viñas, Mercedes; Gázquez-Evangelista, Domingo; Bagur-González, M Gracia

2018-01-15

This paper describes and discusses the application of trimethylsilyl (TMS)-4,4'-desmethylsterols derivatives chromatographic fingerprints (obtained from an off-line HPLC-GC-FID system) for the quantification of extra virgin olive oil in commercial vinaigrettes, dressing salad and in-house reference materials (i-HRM) using two different Partial Least Square-Regression (PLS-R) multivariate quantification methods. Different data pre-processing strategies were carried out being the whole one: (i) internal normalization; (ii) sampling based on The Nyquist Theorem; (iii) internal correlation optimized shifting, icoshift; (iv) baseline correction (v) mean centering and (vi) selecting zones. The first model corresponds to a matrix of dimensions 'n×911' variables and the second one to a matrix of dimensions 'n×431' variables. It has to be highlighted that the proposed two PLS-R models allow the quantification of extra virgin olive oil in binary blends, foodstuffs, etc., when the provided percentage is greater than 25%. Copyright © 2017 Elsevier Ltd. All rights reserved.

Balanced Ambipolar Organic Field-Effect Transistors by Polymer Preaggregation.

PubMed

Janasz, Lukasz; Luczak, Adam; Marszalek, Tomasz; Dupont, Bertrand G R; Jung, Jaroslaw; Ulanski, Jacek; Pisula, Wojciech

2017-06-21

Ambipolar organic field-effect transistors (OFETs) based on heterojunction active films still suffer from an imbalance in the transport of electrons and holes. This problem is related to an uncontrolled phase separation between the donor and acceptor organic semiconductors in the thin films. In this work, we have developed a concept to improve the phase separation in heterojunction transistors to enhance their ambipolar performance. This concept is based on preaggregation of the donor polymer, in this case poly(3-hexylthiophene) (P3HT), before solution mixing with the small-molecular-weight acceptor, phenyl-C61-butyric acid methyl ester (PCBM). The resulting heterojunction transistor morphology consists of self-assembled P3HT fibers embedded in a PCBM matrix, ensuring balanced mobilities reaching 0.01 cm 2 /V s for both holes and electrons. These are the highest mobility values reported so far for ambipolar OFETs based on P3HT/PCBM blends. Preaggregation of the conjugated polymer before fabricating binary blends can be regarded as a general concept for a wider range of semiconducting systems applicable in organic electronic devices.

Ca2+-induced phase separation in black lipid membranes and its effect on the transport of a hydrophobic ion.

PubMed

Miller, A; Schmidt, G; Eibl, H; Knoll, W

1985-03-14

Voltage jump-current relaxation studies have been performed with dipicrylamine-doped black membranes of binary lipid mixtures. As in the case of the carrier-mediated ion transport (Schmidt, G., Eibl, H. and Knoll, W. (1982) J. Membrane Biol. 70, 147-155) no evidence was found that the neutral lipid phosphatidylcholine (DPMPC) and the charged phosphatidic acid (DPMPA) are heterogeneously distributed in the membrane over the whole range of composition. However, besides a continuous dilution of the surface charges of DPMPA by the addition of DPMPC molecules, different structural properties of mixed membranes influence the kinetics of the dipicrylamine transport. The addition of Ca2+ to the electrolyte induces a lipid phase separation within the membrane into two fluid phases of distinctly different characteristics of the translocation of hydrophobic ions. Thus, it is possible to determine a preliminary composition phase diagram for the DPMPA/DPMPC mixtures as a function of the Ca2+ concentration.

Plasma modified nanofibres based on gum kondagogu and their use for collection of nanoparticulate silver, gold and platinum.

PubMed

Padil, Vinod Vellora Thekkae; Stuchlík, Martin; Černík, Miroslav

2015-05-05

Electrospun nanofibre membranes from blend solutions of deacetylated gum kondagogu and polyvinyl alcohol of various weight proportions were prepared. The electrospun membrane was cross linked by heating at 150°C for 6h and later modified by methane plasma treatment. Membranes were successively used for the removal of nanoparticles (Ag, Au and Pt) from water. Pt nanoparticles with the smallest size (2.4 ± 0.7 nm) has a higher adsorption capacity (270.4 mg/g and 327.2mg/g) compared to Au and Ag nanoparticles with particle sizes 7.8 ± 2.3 nm and 10.5 ± 3.5 nm onto nanofibre membrane (NFM) and methane plasma treated membrane (P-NFM). The extraction efficiency of P-NFM for the removal of nanoparticles in water is higher compared to untreated membranes. The adsorption kinetics were evaluated by pseudo-first order and pseudo-second order models for the extraction of nanoparticles from water, with the pseudo-second order model providing a better fit. The reusability and regeneration of the P-NFM for consecutive adsorption was also established. Copyright © 2015 Elsevier Ltd. All rights reserved.

Tailored ß-Cyclodextrin Blocks the Translocation Pores of Binary Exotoxins from C. Botulinum and C. Perfringens and Protects Cells from Intoxication

PubMed Central

Nestorovich, Ekaterina M.; Karginov, Vladimir A.; Popoff, Michel R.; Bezrukov, Sergey M.; Barth, Holger

2011-01-01

Background Clostridium botulinum C2 toxin and Clostridium perfringens iota toxin are binary exotoxins, which ADP-ribosylate actin in the cytosol of mammalian cells and thereby destroy the cytoskeleton. C2 and iota toxin consists of two individual proteins, an enzymatic active (A-) component and a separate receptor binding and translocation (B-) component. The latter forms a complex with the A-component on the surface of target cells and after receptor-mediated endocytosis, it mediates the translocation of the A-component from acidified endosomal vesicles into the cytosol. To this end, the B-components form heptameric pores in endosomal membranes, which serve as translocation channels for the A-components. Methodology/Principal Findings Here we demonstrate that a 7-fold symmetrical positively charged ß-cyclodextrin derivative, per-6-S-(3-aminomethyl)benzylthio-ß-cyclodextrin, protects cultured cells from intoxication with C2 and iota toxins in a concentration-dependent manner starting at low micromolar concentrations. We discovered that the compound inhibited the pH-dependent membrane translocation of the A-components of both toxins in intact cells. Consistently, the compound strongly blocked transmembrane channels formed by the B-components of C2 and iota toxin in planar lipid bilayers in vitro. With C2 toxin, we consecutively ruled out all other possible inhibitory mechanisms showing that the compound did not interfere with the binding of the toxin to the cells or with the enzyme activity of the A-component. Conclusions/Significance The described ß-cyclodextrin derivative was previously identified as one of the most potent inhibitors of the binary lethal toxin of Bacillus anthracis both in vitro and in vivo, implying that it might represent a broad-spectrum inhibitor of binary pore-forming exotoxins from pathogenic bacteria. PMID:21887348

3D-Printed membrane as an alternative to amniotic membrane for ocular surface/conjunctival defect reconstruction: An in vitro & in vivo study.

PubMed

Dehghani, Shima; Rasoulianboroujeni, Morteza; Ghasemi, Hamed; Keshel, Saeed Heidari; Nozarian, Zohreh; Hashemian, Mohammad Naser; Zarei-Ghanavati, Mehran; Latifi, Golshan; Ghaffari, Reza; Cui, Zhanfeng; Ye, Hua; Tayebi, Lobat

2018-05-11

The aim of this study was to evaluate the surgical handling and clinical applicability of a specific 3D-printed membrane design fabricated using a gelatin, elastin and sodium hyaluronate blend for conjunctival reconstruction and compare it with amniotic membrane (AM), which is normally used in such surgeries. 3D printing technique was employed to fabricate the membrane based on gradient design. Prior to printing, rheometry was employed to optimize the ink composition. The printed membranes were then fully characterized in terms of physical and mechanical properties. In vitro viability, proliferation and adhesion of human limbal epithelial cells were assessed using MTT assay and scanning electron microscopy (SEM), respectively. Prior to in vivo experiment, surgical handling of each membrane was evaluated by three surgeons. In vivo evaluation was conducted through implanting the gelatin-based membranes and AM on induced conjunctival defects in rabbits (n = 8). Clinical observations, including epithelialization, inflammation severity, scar tissue formation and presence of granulation tissue, were recorded from day 1 through day 28. Histological examination was performed on all enucleated eyes on day 28. In addition to H&E staining, specific stains including Periodic Acid Schiff staining, Masson's Trichrome staining and immuno-histochemical staining for α-SMA were further used to assess goblet cell proliferation, healed sub-epithelial stroma and scar tissue formation and the presence of myofibroblasts, respectively. Among all the examined compositions, a blend of 8% w/v gelatin, 2% w/v elastin and 0.5% w/v sodium hyaluronate was found to be appropriate for printing. The printed membranes had favorable optical characteristics (colorless and transparent), and the surgical handling was significantly easier compared to AM. Epithelial cells cultivated on the membranes indicated suitable viability and proliferation, and SEM images presented appropriate cell adhesion on the surface of the membranes. Clinical observations suggested similar epithelialization time (approximately 3 weeks) for both the membrane and AM grafted eyes but significantly lower levels of clinical inflammation in the membrane group from day 1 through day 28 (p = 0.01), which is a key advantage of using the printed membranes over the AM. Histological examination showed similar qualities in the healed epithelium in terms of cell morphology and cell layers. However, twice the density of goblet cells per 100 cells was observed in the gelatin-based membrane grafted group. Remnant of the degraded implant was seen in only 3 of the membranes, but in 7 of the AM grafted eyes. Inflammation and granulomatous reaction was significantly higher in sections containing the AM compared to membrane (p < 0.01 and p = 0.01, respectively). α-SMA staining was more evident, but not significantly different from the gelatin-based membrane, for the AM group (p = 0.25). The designed gelatin-based membrane offers the necessary physical and mechanical characteristics needed for successful ocular surface/conjunctival defect construction and may be considered a promising alternative to AM due to a more predictable degradation pattern, higher goblet cell density on the healed epithelium, less inflammation and reduced scar tissue formation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Introducing multiple bio-functional groups on the poly(ether sulfone) membrane substrate to fabricate an effective antithrombotic bio-interface.

PubMed

Wang, Lingren; He, Min; Gong, Tao; Zhang, Xiang; Zhang, Lincai; Liu, Tao; Ye, Wei; Pan, Changjiang; Zhao, Changsheng

2017-11-21

It has been widely recognized that functional groups on biomaterial surfaces play important roles in blood compatibility. To construct an effective antithrombotic bio-interface onto the poly(ether sulfone) (PES) membrane surface, bio-functional groups of sodium carboxylic (-COONa), sodium sulfonic (-SO 3 Na) and amino (-NH 2 ) groups were introduced onto the PES membrane surface in three steps: the synthesis of PES with carboxylic (-COOH) groups (CPES) and water-soluble PES with sodium sulfonic (-SO 3 Na) groups and amino (-NH 2 ) groups (SNPES); the introduction of carboxylic groups onto the PES membrane by blending CPES with PES; and the grafting of SNPES onto CPES/PES membranes via the coupling of amino groups and carboxyl groups. The physical/chemical properties and bioactivities were dependent on the proportions of the additives. After introducing bio-functional groups, the excellent hemocompatibility of the modified membranes was confirmed by the inhibited platelet adhesion and activation, prolonged clotting times, suppressed blood-related complement and leukocyte-related complement receptor activations. Furthermore, cell tests indicated that the modified membranes showed better cytocompatibility in endothelial cell proliferation than the pristine PES membrane due to the synergistic promotion of the functional groups. To sum up, these results suggested that modified membranes present great potential in fields using blood-contacting materials, such as hemodialysis and surface endothelialization.

Dehydration of an ethanol/water azeotrope through alginate-DNA membranes cross-linked with metal ions by pervaporation.

PubMed

Uragami, Tadashi; Banno, Masashi; Miyata, Takashi

2015-12-10

To obtain high dehydration membranes for an ethanol/water azeotrope, dried blend membranes prepared from mixtures of sodium alginate (Alg-Na) and sodium deoxyribonucleate (DNA-Na) were cross-linked by immersing in a methanol solution of CaCl2 or MaCl2. In the dehydration of an ethanol/water azeotropic mixture by pervaporation, the effects of immersion time in methanol solution of CaCl2 or MaCl2 on the permeation rate and water/ethanol selectivity through Alg-DNA/Ca(2+) and Alg-DNA/Mg(2+) cross-linked membranes were investigated. Alg-DNA/Mg(2+) cross-linked membrane immersed for 12h in methanol solution of MaCl2 exhibited the highest water/ethanol selectivity. This results from depressed swelling of the membranes by formation of a cross-linked structure. However, excess immersion in solution containing cross-linker led to an increase in the hydrophobicity of cross-linked membrane. Therefore, the water/ethanol selectivity of Alg-DNA/Mg(2+) cross-linked membranes with an excess immersion in cross-linking solution was lowered. The relationship between the structure of Alg-DNA/Ca(2+) and Alg-DNA/Mg(2+) cross-linked membranes and their permeation and separation characteristics during pervaporation of an ethanol/water azeotropic mixture is discussed in detail. Copyright © 2015 Elsevier Ltd. All rights reserved.

Thermodynamic properties of semiconductor compounds studied based on Debye-Waller factors

NASA Astrophysics Data System (ADS)

Van Hung, Nguyen; Toan, Nguyen Cong; Ba Duc, Nguyen; Vuong, Dinh Quoc

2015-08-01

Thermodynamic properties of semiconductor compounds have been studied based on Debye-Waller factors (DWFs) described by the mean square displacement (MSD) which has close relation with the mean square relative displacement (MSRD). Their analytical expressions have been derived based on the statistical moment method (SMM) and the empirical many-body Stillinger-Weber potentials. Numerical results for the MSDs of GaAs, GaP, InP, InSb, which have zinc-blende structure, are found to be in reasonable agreement with experiment and other theories. This paper shows that an elements value for MSD is dependent on the binary semiconductor compound within which it resides.

Novel, Solvent-Free, Single Ion-Conducting Polymer Electrolytes

DTIC Science & Technology

2007-10-31

the selected polymer electrolyte membrane and a LiFePO4 -based composite cathode film. The latter was prepared by blending the LiFePO4 active...following: charge Li+ + FePO4 + e LiFePO4 [1] discharge to which is associate a maximum...as separator in a Li/ LiFePO4 battery. . 1.Experimental. Calixpyrrole (CP, provided by the University of Warsaw), LiBOB (Libby) and PEO

DNA Based Electrochromic and Photovoltaic Cells

DTIC Science & Technology

2012-01-01

electrolyte/CeO2- TiO2 /ITO/glass configuration [29]. 2. Experimental 2.1 Gel polymeric electrolytes The electrolytes were prepared according to the...transparent membranes. Blend samples were also prepared by the addition of other macromolecules (gelatin), synthetic polymers, such as poly(ethylene...Electrochromic devices Electrochromic devices with the glass/ITO/WO3/DNA-based electrolyte/CeO2- TiO2 /ITO/glass configuration were obtained by assembling

Fast measurement of proton exchange membrane fuel cell impedance based on pseudo-random binary sequence perturbation signals and continuous wavelet transform

NASA Astrophysics Data System (ADS)

Debenjak, Andrej; Boškoski, Pavle; Musizza, Bojan; Petrovčič, Janko; Juričić, Đani

2014-05-01

This paper proposes an approach to the estimation of PEM fuel cell impedance by utilizing pseudo-random binary sequence as a perturbation signal and continuous wavelet transform with Morlet mother wavelet. With the approach, the impedance characteristic in the frequency band from 0.1 Hz to 500 Hz is identified in 60 seconds, approximately five times faster compared to the conventional single-sine approach. The proposed approach was experimentally evaluated on a single PEM fuel cell of a larger fuel cell stack. The quality of the results remains at the same level compared to the single-sine approach.

New insight of hybrid membrane to degrade Congo red and Reactive yellow under sunlight.

PubMed

Rajeswari, A; Jackcina Stobel Christy, E; Pius, Anitha

2018-02-01

A study was carried out to investigate the degradation of organic contaminants (Congo red and Reactive yellow - 105) using cellulose acetate - polystyrene (CA-PS) membrane with and without ZnO impregnation. Scanning electron microscope (SEM), electron dispersive analysis of X-rays (EDAX), Fourier transform infrared spectrometer (FTIR), atomic force microscope (AFM) and thermogravimeric analysis (TG-DTA) analysis were carried out to characterize bare and ZnO impregnated CA-PS membranes. Membrane efficiency was also tested for pure water flux and antifouling performance. The modified membrane showed almost 85% water flux recovery. Blending of ZnO nanoparticles to CA-PS matrix could decrease membrane fouling and increase permeation quality of the membrane with above 90% of photocatalytic degradation efficiency for dyes. The rate of degradation of dyes was observed using UV-Vis spectrometer. Reusability of CA-PS-ZnO membrane was studied and no significant change was noted in the degradation efficiency until fourth cycle. Langmuir-Hinshelwood kinetic model well describes the photo degradation capacity and the degradation of dyes CR and RY - 105 exhibited pseudo-first order kinetics. The regression coefficient (R) of CR and RY - 105 found to be 0.99. The novelty of the prepared CA-PS-ZnO membrane is that it has better efficiency and high thermal stability than our previously reported material. Therefore, ZnO impregnated CA-PS membrane had proved to be an innovative alternative for the degradation of CR and RY - 105 dyes. Copyright © 2017 Elsevier B.V. All rights reserved.

Membrane-based technologies for biogas separations.

PubMed

Basu, Subhankar; Khan, Asim L; Cano-Odena, Angels; Liu, Chunqing; Vankelecom, Ivo F J

2010-02-01

Over the past two decades, membrane processes have gained a lot of attention for the separation of gases. They have been found to be very suitable for wide scale applications owing to their reasonable cost, good selectivity and easily engineered modules. This critical review primarily focuses on the various aspects of membrane processes related to the separation of biogas, more in specific CO(2) and H(2)S removal from CH(4) and H(2) streams. Considering the limitations of inorganic materials for membranes, the present review will only focus on work done with polymeric materials. An overview on the performance of commercial membranes and lab-made membranes highlighting the problems associated with their applications will be given first. The development studies carried out to enhance the performance of membranes for gas separation will be discussed in the subsequent section. This review has been broadly divided into three sections (i) performance of commercial polymeric membranes (ii) performance of lab-made polymeric membranes and (iii) performance of mixed matrix membranes (MMMs) for gas separations. It will include structural modifications at polymer level, polymer blending, as well as synthesis of mixed matrix membranes, for which addition of silane-coupling agents and selection of suitable fillers will receive special attention. Apart from an overview of the different membrane materials, the study will also highlight the effects of different operating conditions that eventually decide the performance and longevity of membrane applications in gas separations. The discussion will be largely restricted to the studies carried out on polyimide (PI), cellulose acetate (CA), polysulfone (PSf) and polydimethyl siloxane (PDMS) membranes, as these membrane materials have been most widely used for commercial applications. Finally, the most important strategies that would ensure new commercial applications will be discussed (156 references).

Preparation and characterization of novel PVDF nanofiltration membranes with hydrophilic property for filtration of dye aqueous solution

NASA Astrophysics Data System (ADS)

Nikooe, Naeme; Saljoughi, Ehsan

2017-08-01

In the present research, for the first time PVDF/Brij-58 blend nanofiltration membranes with remarkable performance in filtration of dye aqueous solution were prepared via immersion precipitation. A noticeable improvement in water permeation and fouling resistance of the PVDF membranes was achieved by using Brij-58 surfactant as a hydrophilic additive. Scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR) and water contact angle were applied for the investigation of membrane morphology, detection of the surface chemical composition and relative hydrophilicity/hydrophobicity, respectively. The membrane performance was studied and compared by determination of pure water flux (PWF) and filtration of synthetic reactive dye aqueous solutions as well as bovine serum albumin (BSA) as foulant model. It was found out that addition of 4 wt.% Brij-58 to the casting solution results in formation of membrane with remarkable hydrophilicity and fouling resistance (contact angle of 46° and flux recovery ratio (FRR) = 90%), higher porosity and consequently noticeable PWF (31.2 L/m2 h) and recognized dye rejection value (90%) in comparison with the pristine PVDF nanofiltration membrane. Addition of Brij-58 surfactant to the casting solution resulted in formation of NF membrane with higher hydrophilicity and permeability as well as higher dye rejection value in comparison with the addition of PEG 400 additive.

Development of a nanocomposite ultrafiltration membrane based on polyphenylsulfone blended with graphene oxide

PubMed Central

Shukla, Arun Kumar; Alam, Javed; Alhoshan, Mansour; Dass, Lawrence Arockiasamy; Muthumareeswaran, M. R.

2017-01-01

In the present study, graphene oxide (GO) was incorporated as a nanoadditive into a polyphenylsulfone (PPSU) to develop a PPSU/GO nanocomposite membrane with enhanced antifouling properties. A series of membranes containing different concentrations (0.2, 0.5 and 1.0 wt.%) of GO were fabricated via the phase inversion method, using N-methyl pyrrolidone (NMP) as the solvent, deionized water as the non-solvent, and polyvinylpyrrolidone (PVP) as a pore forming agent. The prepared nanocomposite membranes were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM), and were also characterized with respect to contact angle, zeta potential and porosity, mean pore radius, tortuosity and molecular weight cut-off (MWCO). Thermogravimetric analysis (TGA) and tensile testing were used to measure thermal and mechanical properties. The membrane performance was evaluated by volumetric flux and rejection of proteins, and antifouling properties. According to the results, the optimum addition of 0.5 wt% GO resulted in a membrane with an increased flux of 171 ± 3 Lm−2h−1 with a MWCO of ~40 kDa. In addition, the GO incorporation efficiently inhibited the interaction between proteins and the membrane surface, thereby improving the fouling resistance ability by approximately 58 ± 3%. Also, the resulting membranes showed a significant improvement in mechanical and thermal properties. PMID:28155882

Development of a nanocomposite ultrafiltration membrane based on polyphenylsulfone blended with graphene oxide

NASA Astrophysics Data System (ADS)

Shukla, Arun Kumar; Alam, Javed; Alhoshan, Mansour; Dass, Lawrence Arockiasamy; Muthumareeswaran, M. R.

2017-02-01

In the present study, graphene oxide (GO) was incorporated as a nanoadditive into a polyphenylsulfone (PPSU) to develop a PPSU/GO nanocomposite membrane with enhanced antifouling properties. A series of membranes containing different concentrations (0.2, 0.5 and 1.0 wt.%) of GO were fabricated via the phase inversion method, using N-methyl pyrrolidone (NMP) as the solvent, deionized water as the non-solvent, and polyvinylpyrrolidone (PVP) as a pore forming agent. The prepared nanocomposite membranes were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM), and were also characterized with respect to contact angle, zeta potential and porosity, mean pore radius, tortuosity and molecular weight cut-off (MWCO). Thermogravimetric analysis (TGA) and tensile testing were used to measure thermal and mechanical properties. The membrane performance was evaluated by volumetric flux and rejection of proteins, and antifouling properties. According to the results, the optimum addition of 0.5 wt% GO resulted in a membrane with an increased flux of 171 ± 3 Lm-2h-1 with a MWCO of ~40 kDa. In addition, the GO incorporation efficiently inhibited the interaction between proteins and the membrane surface, thereby improving the fouling resistance ability by approximately 58 ± 3%. Also, the resulting membranes showed a significant improvement in mechanical and thermal properties.

Effect of intrinsic curvature and edge tension on the stability of binary mixed-membrane three-junctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gardner, Jasmine M.; Abrams, Cameron F.; Deserno, Markus

We use a combination of coarse-grained molecular dynamics simulations and theoretical modeling to examine three-junctions in mixed lipid bilayer membranes. These junctions are localized defect lines in which three bilayers merge in such a way that each bilayer shares one monolayer with one of the other two bilayers. The resulting local morphology is non-lamellar, resembling the threefold symmetric defect lines in inverse hexagonal phases, but it regularly occurs during membrane fission and fusion events. We realize a system of junctions by setting up a honeycomb lattice, which in its primitive cell contains two hexagons and four three-line junctions, permitting usmore » to study their stability as well as their line tension. We specifically consider the effects of lipid composition and intrinsic curvature in binary mixtures, which contain a fraction of negatively curved lipids in a curvature-neutral background phase. Three-junction stability results from a competition between the junction and an open edge, which arises if one of the three bilayers detaches from the other two. We show that the stable phase is the one with the lower defect line tension. The strong and opposite monolayer curvatures present in junctions and edges enhance the mole fraction of negatively curved lipids in junctions and deplete it in edges. This lipid sorting affects the two line tensions and in turn the relative stability of the two phases. It also leads to a subtle entropic barrier for the transition between junction and edge that is absent in uniform membranes.« less

Ethanol effects on binary and ternary supported lipid bilayers with gel/fluid domains and lipid rafts.

PubMed

Marquês, Joaquim T; Viana, Ana S; De Almeida, Rodrigo F M

2011-01-01

Ethanol-lipid bilayer interactions have been a recurrent theme in membrane biophysics, due to their contribution to the understanding of membrane structure and dynamics. The main purpose of this study was to assess the interplay between membrane lateral heterogeneity and ethanol effects. This was achieved by in situ atomic force microscopy, following the changes induced by sequential ethanol additions on supported lipid bilayers formed in the absence of alcohol. Binary phospholipid mixtures with a single gel phase, dipalmitoylphosphatidylcholine (DPPC)/cholesterol, gel/fluid phase coexistence DPPC/dioleoylphosphatidylcholine (DOPC), and ternary lipid mixtures containing cholesterol, mimicking lipid rafts (DOPC/DPPC/cholesterol and DOPC/sphingomyelin/cholesterol), i.e., with liquid ordered/liquid disordered (ld/lo) phase separation, were investigated. For all compositions studied, and in two different solid supports, mica and silicon, domain formation or rearrangement accompanied by lipid bilayer thinning and expansion was observed. In the case of gel/fluid coexistence, low ethanol concentrations lead to a marked thinning of the fluid but not of the gel domains. In the case of ld/lo all the bilayer thins simultaneously by a similar extent. In both cases, only the more disordered phase expanded significantly, indicating that ethanol increases the proportion of disordered domains. Water/bilayer interfacial tension variation and freezing point depression, inducing acyl chain disordering (including opening and looping), tilting, and interdigitation, are probably the main cause for the observed changes. The results presented herein demonstrate that ethanol influences the bilayer properties according to membrane lateral organization. Copyright © 2010 Elsevier B.V. All rights reserved.

An in vitro evaluation of various biomaterials for the development of a tissue-engineered lacrimal gland

NASA Astrophysics Data System (ADS)

Selvam, Shivaram

The most common cause of ocular morbidity in developed countries is dry eye, many cases of which are due to lacrimal insufficiency. It has been established that lacrimal insufficiency results from processes caused by both immune-related and non-immune related events such as Sjogren's syndrome, Stevens-Johnson syndrome, chemical and thermal injuries and ocular cicatricial pemphigoid. Patients with these conditions would benefit from repair of their damaged lacrimal tissue by the creation of a replacement for the lacrimal gland. The new field of tissue engineering built on the interface between principles and methods of the life sciences with those of engineering to develop biocompatible materials has created the possibility for repairing or replacing damaged tissues. This thesis explores the use of tissue engineering principles for the development of a tissue-engineered lacrimal gland. This thesis also contributes to the development of a novel model for addressing lacrimal gland physiology and epithelial fluid transport. The first part of the research work focused on the evaluation of morphological and physiological properties of purified lacrimal gland acinar cells (pLGACs) cultured on various biopolymers: silicone, collagen I, poly-D,L-lactide-co-glycolide (PLGA; 85:15 and 50:50), and poly-L-lactic acid (PLLA) in the presence and absence of an extracellular matrix, MatrigelRTM. Results indicated that PLLA demonstrated the best support expression of acinar cell-like morphology. The second part demonstrated the ex vivo reconstitution of an electrophysiologically functional lacrimal gland tissue on porous polyester membrane scaffolds. Results showed that pLGACs were capable of establishing continuous epithelial monolayers that generate active ionic fluxes consistent with current models for Na +-dependent Cl-- secretion. The third part outlined the fabrication of porous PLLA membranes, the optimal biomaterial for culturing lacrimal epithelial cells. Microporous PLLA-Polyethylene glycol (PEG) blend membranes (mpPLLAbm) with interconnected pores were prepared by the water extraction of PEG from solution cast blend membranes using the solvent-cast/particulate leaching technique. Diffusion experiments on mpPLLAbm (57.1/42.9 wt%) were performed to demonstrate that the membrane was permeable to glucose, L-tryptophan, and dextran.

Enhanced Flux and Electrochemical Cleaning of Silicate Scaling on Carbon Nanotube-Coated Membrane Distillation Membranes Treating Geothermal Brines

DOE PAGES

Tang, Li; Iddya, Arpita; Zhu, Xiaobo; ...

2017-10-13

The desalination of inland brackish groundwater offers the opportunity to provide potable drinking water to residents and industrial cooling water to industries located in arid regions. Geothermal brines are used to generate electricity, but often contain high concentrations of dissolved salt. Here in this paper, we demonstrate how the residual heat left in spent geothermal brines can be used to drive a membrane distillation (MD) process and recover desalinated water. Porous polypropylene membranes were coated with a carbon nanotube (CNT)/poly(vinyl alcohol) layer, resulting in composite membranes having a binary structure that combines the hydrophobic properties critical for MD with themore » hydrophilic and conductive properties of the CNTs. We demonstrate that the addition of the CNT layer increases membrane flux due to enhanced heat transport from the bulk feed to the membrane surface, a result of CNT's high thermal transport properties. Furthermore, we show how hydroxide ion generation, driven by water electrolysis on the electrically conducting membrane surface, can be used to efficiently dissolve silicate scaling that developed during the process of desalinating the geothermal brine, negating the need for chemical cleaning.« less

Enhanced Flux and Electrochemical Cleaning of Silicate Scaling on Carbon Nanotube-Coated Membrane Distillation Membranes Treating Geothermal Brines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Li; Iddya, Arpita; Zhu, Xiaobo

The desalination of inland brackish groundwater offers the opportunity to provide potable drinking water to residents and industrial cooling water to industries located in arid regions. Geothermal brines are used to generate electricity, but often contain high concentrations of dissolved salt. Here in this paper, we demonstrate how the residual heat left in spent geothermal brines can be used to drive a membrane distillation (MD) process and recover desalinated water. Porous polypropylene membranes were coated with a carbon nanotube (CNT)/poly(vinyl alcohol) layer, resulting in composite membranes having a binary structure that combines the hydrophobic properties critical for MD with themore » hydrophilic and conductive properties of the CNTs. We demonstrate that the addition of the CNT layer increases membrane flux due to enhanced heat transport from the bulk feed to the membrane surface, a result of CNT's high thermal transport properties. Furthermore, we show how hydroxide ion generation, driven by water electrolysis on the electrically conducting membrane surface, can be used to efficiently dissolve silicate scaling that developed during the process of desalinating the geothermal brine, negating the need for chemical cleaning.« less

[Computer modeling the hydrostatic pressure characteristics of the membrane potential for polymeric membrane, separated non-homogeneous electrolyte solutions].

PubMed

Slezak, Izabella H; Jasik-Slezak, Jolanta; Rogal, Mirosława; Slezak, Andrzej

2006-01-01

On the basis of model equation depending the membrane potential deltapsis, on mechanical pressure difference (deltaP), concentration polarization coefficient (zetas), concentration Rayleigh number (RC) and ratio concentration of solutions separated by membrane (Ch/Cl), the characteristics deltapsis = f(deltaP)zetas,RC,Ch/Cl for steady values of zetas, RC and Ch/Cl in single-membrane system were calculated. In this system neutral and isotropic polymeric membrane oriented in horizontal plane, the non-homogeneous binary electrolytic solutions of various concentrations were separated. Nonhomogeneity of solutions is results from creations of the concentration boundary layers on both sides of the membrane. Calculations were made for the case where on a one side of the membrane aqueous solution of NaCl at steady concentration 10(-3) mol x l(-1) (Cl) was placed and on the other aqueous solutions of NaCl at concentrations from 10(-3) mol x l(-1) to 2 x 10(-2) mol x l(-1) (Ch). Their densities were greater than NaCl solution's at 10(-3) mol x l(-1). It was shown that membrane potential depends on hydrodynamic state of a complex concentration boundary layer-membrane-concentration boundary layer, what is controlled by deltaP, Ch/Cl, RC and zetas.

Hierarchical Materials Design by Pattern Transfer Printing of Self-Assembled Binary Nanocrystal Superlattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paik, Taejong; Yun, Hongseok; Fleury, Blaise

We demonstrate the fabrication of hierarchical materials by controlling the structure of highly ordered binary nanocrystal superlattices (BNSLs) on multiple length scales. Combinations of magnetic, plasmonic, semiconducting, and insulating colloidal nanocrystal (NC) building blocks are self-assembled into BNSL membranes via the liquid–interfacial assembly technique. Free-standing BNSL membranes are transferred onto topographically structured poly(dimethylsiloxane) molds via the Langmuir–Schaefer technique and then deposited in patterns onto substrates via transfer printing. BNSLs with different structural motifs are successfully patterned into various meso- and microstructures such as lines, circles, and even three-dimensional grids across large-area substrates. A combination of electron microscopy and grazing incidencemore » small-angle X-ray scattering (GISAXS) measurements confirm the ordering of NC building blocks in meso- and micropatterned BNSLs. This technique demonstrates structural diversity in the design of hierarchical materials by assembling BNSLs from NC building blocks of different composition and size by patterning BNSLs into various size and shape superstructures of interest for a broad range of applications.« less

Flash nano-precipitation of polymer blends: a role for fluid flow?

NASA Astrophysics Data System (ADS)

Grundy, Lorena; Mason, Lachlan; Chergui, Jalel; Juric, Damir; Craster, Richard V.; Lee, Victoria; Prudhomme, Robert; Priestley, Rodney; Matar, Omar K.

2017-11-01

Porous structures can be formed by the controlled precipitation of polymer blends; ranging from porous matrices, with applications in membrane filtration, to porous nano-particles, with applications in catalysis, targeted drug delivery and emulsion stabilisation. Under a diffusive exchange of solvent for non-solvent, prevailing conditions favour the decomposition of polymer blends into multiple phases. Interestingly, dynamic structures can be `trapped' via vitrification prior to thermodynamic equilibrium. A promising mechanism for large-scale polymer processing is flash nano-precipitation (FNP). FNP particle formation has recently been modelled using spinodal decomposition theory, however the influence of fluid flow on structure formation is yet to be clarified. In this study, we couple a Navier-Stokes equation to a Cahn-Hilliard model of spinodal decomposition. The framework is implemented using Code BLUE, a massively scalable fluid dynamics solver, and applied to flows within confined impinging jet mixers. The present method is valid for a wide range of mixing timescales spanning FNP and conventional immersion precipitation processes. Results aid in the fabrication of nano-scale polymer particles with tuneable internal porosities. EPSRC, UK, MEMPHIS program Grant (EP/K003976/1), RAEng Research Chair (OKM), PETRONAS.

The wettability and swelling of selected mucoadhesive polymers in simulated saliva and vaginal fluids.

PubMed

Rojewska, M; Olejniczak-Rabinek, M; Bartkowiak, A; Snela, A; Prochaska, K; Lulek, J

2017-08-01

The surface properties play a particularly important role in the mucoadhesive drug delivery systems. In these formulations, the adsorption of polymer matrix to mucous membrane is limited by the wetting and swelling process of the polymer structure. Hence, the performance of mucoadhesive drug delivery systems made of polymeric materials depends on multiple factors, such as contact angle, surface free energy and water absorption rate. The aim of our study was to analyze the effect of model saliva and vaginal fluids on the wetting properties of selected mucoadhesive (Carbopol 974P NF, Noveon AA-1, HEC) and film-forming (Kollidon VA 64) polymers as well as their blends at the weight ratio 1:1 and 1:1:1, prepared in the form of discs. Surface properties of the discs were determined by measurements of advancing contact angle on the surface of polymers and their blends using the sessile drop method. The surface energy was determined by the OWRK method. Additionally, the mass swelling factor and hydration percentage of examined polymers and their blends in simulated biological fluids were evaluated. Copyright © 2017 Elsevier B.V. All rights reserved.

Biochar composite membrane for high performance pollutant management: Fabrication, structural characteristics and synergistic mechanisms.

PubMed

Ghaffar, Abdul; Zhu, Xiaoying; Chen, Baoliang

2018-02-01

Biochar, a natural sourced carbon-rich material, has been used commonly in particle shape for carbon sequestration, soil fertility and environmental remediation. Here, we report a facile approach to fabricate freestanding biochar composite membranes for the first time. Wood biochars pyrolyzed at 300 °C and 700 °C were blended with polyvinylidene fluoride (PVdF) in three percentages (10%, 30% and 50%) to construct membranes through thermal phase inversion process. The resultant biochar composite membranes possess high mechanical strength and porous structure with uniform distribution of biochar particles throughout the membrane surface and cross-section. The membrane pure water flux was increased with B300 content (4825-5411 ± 21 L m -2 h -1 ) and B700 content (5823-6895 ± 72 L m -2 h -1 ). The membranes with B300 were more hydrophilic with higher surface free energy (58.84-60.31 mJ m -2 ) in comparison to B700 (56.32-51.91 mJ m -2 ). The biochar composite membranes indicated promising adsorption capacities (47-187 mg g -1 ) to Rhodamine B (RhB) dye. The biochar membranes also exhibited high retention (74-93%) for E. coli bacterial suspensions through filtration. After simple physical cleaning, both the adsorption and sieving capabilities of the biochar composite membranes could be effectively recovered. Synergistic mechanisms of biochar/PVdF in the composite membrane are proposed to elucidate the high performance of the membrane in pollutant management. The multifunctional biochar composite membrane not only effectively prevent the problems caused by directly using biochar particle as sorbent but also can be produced in large scale, indicating great potential for practical applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Iron-tannin-framework complex modified PES ultrafiltration membranes with enhanced filtration performance and fouling resistance.

PubMed

Fang, Xiaofeng; Li, Jiansheng; Li, Xin; Pan, Shunlong; Sun, Xiuyun; Shen, Jinyou; Han, Weiqing; Wang, Lianjun; Van der Bruggen, Bart

2017-11-01

In this work, an iron-tannin-framework (ITF) complex was introduced to a poly (ether sulfone) (PES) casting solution as a hydrophilic additive to fabricate ITF/PES ultrafiltration (UF) membranes via non-solvent-induced phase separation (NIPS). The structure and performance of the PES membranes with ITF concentrations ranging from 0 to 0.9wt.% were systematically investigated by scanning electron microscopy, water contact angle, permeability, protein rejection and fouling resistance measurements. The results indicate that the pore structure and surface properties of PES UF membranes can be regulated by incorporating the ITF complex. Compared with classical PES membranes, ITF/PES membranes were found to have an increased hydrophilicity and porosity and reduced surface pore size. Importantly, a simultaneous enhancement of permeability and separation performance was observed for the blend membranes, which indicates that the introduction of the ITF complex can break through the trade-off between permeability and selectivity of UF membranes.When the ITF content was 0.3wt.%, the permeability reached a maximum of 319.4(L/m 2 h) at 0.1MPa, which is 1.6 times higher than that of the classical PES membrane. Furthermore, the BSA rejection increased from 25.9% for the PES membrane to 95.9% for the enhanced membrane. In addition, the same membrane showed an improved fouling resistance (higher flux recovery and lower adhesion force) and stable hydrophilicity (unchanged after incubation in deionized water for 30days). The simple, green and cost-effective preparation process and the outstanding filtration performance highlight the potential of ITF/PES membranes for practical applications. Copyright © 2017 Elsevier Inc. All rights reserved.

Development of Polyvinylidene fluoride (PVDF)-ZIF-8 Membrane for Wastewater Treatment

NASA Astrophysics Data System (ADS)

Ibrahim, N. A.; Wirzal, M. D. H.; Nordin, N. A. H.; Halim, N. S. Abd

2018-04-01

Nowadays, the water shortage problem following the urbanization and increasing pollution of natural water source have increased the awareness to treat wastewater. Membrane filtration is often used in wastewater treatment plants to filter out more residual activated sludge from aeration process in the secondary stage. However, fouling is the main concern due to the fact it can happen to any membrane application. Antifouling properties in membrane can be improved by blending membranes with fillers or additives to make them more hydrophilic. This study aims to improve the antifouling properties in polyvinylidene fluoride (PVDF) membranes while optimizing the loading of Zeolitic imidazolate framework-8 (ZIF-8) fillers; at different loading (2.0 wt. %, 4.0 wt. %, 6.0 wt. %, 8.0 wt. % and 10.0 wt. %). Manual hand-casting of flat sheet membrane was done and the fabricated membranes were tested for their filterability against pure water and domestic wastewater. Both permeability tests showed that PVDF with 8% ZIF-8 membrane was the most permeable with a pure water and wastewater permeability of 150 L/m2.h.bar and 94 L/m2.h.bar, respectively. The pure water permeability of PVDF with 8% ZIF-8 membrane increases for about 130% compared to the pure PVDF membrane. The turbidity test of the initial feed and final permeate of wastewater, PVDF with 8% ZIF-8 membrane also gave out the highest reduction rate at 87%, which is 36% higher than that of pure PVDF membrane. It can be deduced that 8% of ZIF-8 is the ideal loading to PVDF in improving its antifouling properties to be used in domestic wastewater treatment.

Membrane formation in liquids by adding an antagonistic salt

NASA Astrophysics Data System (ADS)

Sadakane, Koichiro; Seto, Hideki

2018-03-01

Antagonistic salts are composed of hydrophilic and hydrophobic ions. In a binary mixture, such as water and organic solvent, these ion pairs preferentially dissolve to those phases, respectively, and there is a coupling between the charge density and the composition. The heterogeneous distribution of ions forms a large electric double layer at the interface between these solvents. This reduces the interfacial tension between water and organic solvent, and stabilizes an ordered structure, such as a membrane. These phenomena have been extensively studied from both theoretical and experimental point of view. In addition, the numerical simulations can reproduce such ordered structures.

Separating the Spectral Components of the Massive Triple Star System Delta Orionis

NASA Astrophysics Data System (ADS)

Gies, Douglas

2013-10-01

The multiple star system of delta Orionis represents one of the closest examples of a luminous O-star with a strong stellar wind, and it was the target of a recent multi-wavelength campaign to determine the source of the wind X-ray emission. It consists of aclose eclipsing binary with a more distant tertiary, and all the components are massive stars. Investigations of the radial velocity curves of the eclipsing system are made difficult by severe line blending with the spectral lines of the tertiary star, and the resulting mass estimates range by a factor of two. We propose that the solution to this problem is to isolate the flux of the tertiary through high angular resolutionspectroscopy with HST/STIS, and we show how a two visit program of ultraviolet and spatially resolved spectroscopy will provide us with the means to characterize the spectra of all three stars in the triple. This will allow us to reassess a large body of existing optical and UV spectroscopy and determine reliable radial velocity curves for the components in the close binary. By then fitting a new high precision light curve from MOST photometry, we will derive accurate masses, temperatures, radii, and projected rotational velocities for all the components. The inner binary also hasa measured apsidal period, and the new results will form a key test of models of interior structure. The analysis will also provide secure estimates for the geometry and size of the inner binary and the radius of the secondary, the parameters required to analyze the orbital phase variations and sites of origin of the wind X-ray emission documented in a recent Chandra/HETGS program.

VizieR Online Data Catalog: Double stars with wide separations in the AGK3 (Halbwachs+, 2016)

NASA Astrophysics Data System (ADS)

Halbwachs, J. L.; Mayor, M.; Udry, S.

2016-10-01

A large list of common proper motion stars selected from the third Astronomischen Gesellschaft Katalog (AGK3) was monitored with the CORAVEL (for COrrelation RAdial VELocities) spectrovelocimeter, in order to prepare a sample of physical binaries with very wide separations. In paper I,66 stars received special attention, since their radial velocities (RV) seemed to be variable. These stars were monitored over several years in order to derive the elements of their spectroscopic orbits. In addition, 10 of them received accurate RV measurements from the SOPHIE spectrograph of the T193 telescope at the Observatory of Haute-Provence. For deriving the orbital elements of double-lined spectroscopic binaries (SB2s), a new method was applied, which assumed that the RV of blended measurements are linear combinations of the RV of the components. 13 SB2 orbits were thus calculated. The orbital elements were eventually obtained for 52 spectroscopic binaries (SBs), two of them making a triple system. 40 SBs received their first orbit and the orbital elements were improved for 10 others. In addition, 11 SBs were discovered with very long periods for which the orbital parameters were not found. It appeared that HD 153252 has a close companion, which is a candidate brown dwarf with a minimum mass of 50 Jupiter masses. In paper II, 80 wide binaries (WBs) were detected, and 39 optical pairs were identified. Adding CPM stars with separations close enough to be almost certain they are physical, a "bias-controlled" sample of 116 wide binaries was obtained, and used to derive the distribution of separations from 100 to 30,000 au. The distribution obtained doesn't match the log-constant distribution, but is in agreement with the log-normal distribution. The spectroscopic binaries detected among the WB components were used to derive statistical informations about the multiple systems. The close binaries in WBs seem to be similar to those detected in other field stars. As for the WBs, they seem to obey the log-normal distribution of periods. The number of quadruple systems is in agreement with the "no correlation" hypothesis; this indicates that an environment conducive to the formation of WBs doesn't favor the formation of subsystems with periods shorter than 10 years. (9 data files).

A Probabilistic Mass Estimation Algorithm for a Novel 7- Channel Capacitive Sample Verification Sensor

NASA Technical Reports Server (NTRS)

Wolf, Michael

2012-01-01

A document describes an algorithm created to estimate the mass placed on a sample verification sensor (SVS) designed for lunar or planetary robotic sample return missions. A novel SVS measures the capacitance between a rigid bottom plate and an elastic top membrane in seven locations. As additional sample material (soil and/or small rocks) is placed on the top membrane, the deformation of the membrane increases the capacitance. The mass estimation algorithm addresses both the calibration of each SVS channel, and also addresses how to combine the capacitances read from each of the seven channels into a single mass estimate. The probabilistic approach combines the channels according to the variance observed during the training phase, and provides not only the mass estimate, but also a value for the certainty of the estimate. SVS capacitance data is collected for known masses under a wide variety of possible loading scenarios, though in all cases, the distribution of sample within the canister is expected to be approximately uniform. A capacitance-vs-mass curve is fitted to this data, and is subsequently used to determine the mass estimate for the single channel s capacitance reading during the measurement phase. This results in seven different mass estimates, one for each SVS channel. Moreover, the variance of the calibration data is used to place a Gaussian probability distribution function (pdf) around this mass estimate. To blend these seven estimates, the seven pdfs are combined into a single Gaussian distribution function, providing the final mean and variance of the estimate. This blending technique essentially takes the final estimate as an average of the estimates of the seven channels, weighted by the inverse of the channel s variance.

Continuous esterification to produce biodiesel by SPES/PES/NWF composite catalytic membrane in flow-through membrane reactor: experimental and kinetic studies.

PubMed

Shi, Wenying; He, Benqiao; Cao, Yuping; Li, Jianxin; Yan, Feng; Cui, Zhenyu; Zou, Zhiqun; Guo, Shiwei; Qian, Xiaomin

2013-02-01

A novel composite catalytic membrane (CCM) was prepared from sulfonated polyethersulfone (SPES) and polyethersulfone (PES) blend supported by non-woven fabrics, as a heterogeneous catalyst to produce biodiesel from continuous esterification of oleic acid with methanol in a flow-through mode. A kinetic model of esterification was established based on a plug-flow assumption. The effects of the CCM structure (thickness, area, porosity, etc.), reaction temperature and the external and internal mass transfer resistances on esterification were investigated. The results showed that the CCM structure had a significant effect on the acid conversion. The external mass transfer resistance could be neglected when the flow rate was over 1.2 ml min(-1). The internal mass transfer resistance impacted on the conversion when membrane thickness was over 1.779 mm. An oleic acid conversion kept over 98.0% for 500 h of continuous running. The conversions obtained from the model are in good agreement with the experimental data. Copyright © 2012 Elsevier Ltd. All rights reserved.

Hemocompatibility evaluation of poly(1,8-octanediol citrate) blend polyethersulfone membranes.

PubMed

Zailani, Muhamad Zulhilmi; Ismail, Ahmad Fauzi; Sheikh Abdul Kadir, Siti Hamimah; Othman, Mohd Hafiz Dzarfan; Goh, Pei Sean; Hasbullah, Hasrinah; Abdullah, Mohd Sohaimi; Ng, Be Cheer; Kamal, Fatmawati

2017-05-01

In this study, poly (1,8-octanediol citrate) (POC) was used to modify polyethersulfone (PES)-based membrane to enhance its hemocompatibility. Different compositions of POC (0-3%) were added into the polyethersulfone (PES) dope solutions and polyvinylpyrrolidone (PVP) was used as pore forming agent. The hemocompatible POC modified PES membranes were fabricated through phase-inversion technique. The prepared membranes were characterized using attenuated total reflectance-Fourier transform infrared (ATR-FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Atomic-force microscopy (AFM), contact angle, Zeta-potential, membrane porosity and pore size and pure water flux (PWF) and BSA rejection. The hemocompatibility of the modified PES membranes was evaluated by human serum fibrinogen (FBG) protein adsorption, platelet adhesion, activated partial thromboplastin time (APTT) and prothrombin time (PT), and thrombin-antithrombin III (TAT), complement (C3a and C5a) activation and Ca 2+ absorption on membrane. Results showed that by increasing POC concentration, FBG adsorption was reduced, less platelets adhesion, prolonged APTT and PT, lower TAT, C5a and C3a activation and absorb more Ca 2+ ion. These results indicated that modification of PES with POC has rendered improved hemocompatibility properties for potential application in the field of blood purification, especially in hemodialysis. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1510-1520, 2017. © 2017 Wiley Periodicals, Inc.

Synthesis and Electrospraying of Nanoscale MOF (Metal Organic Framework) for High-Performance CO2 Adsorption Membrane

NASA Astrophysics Data System (ADS)

Wahiduzzaman; Allmond, Kelsey; Stone, John; Harp, Spencer; Mujibur, Khan

2017-01-01

We report the sonochemical synthesis of MOF (metal organic framework) nanoparticles of 30-200 nm in size and electrospraying of those particles on electrospun nanofibers to process a MOF-attached nanofibrous membrane. This membrane displayed significant selectivity towards CO2 and capacity of adsorbing with 4000-5000 ppm difference from a mixed gas flow of 1% CO2 and 99% N2. Applying ultrasonic waves during the MOF synthesis offered rapid dispersion and formation of crystalline MOF nanoparticles in room temperature. The MOF nanoparticles of 100-200 nm in size displayed higher surface area and adsorption capacity comparing to that of 30-60 nm in size. Nanofibrous membrane was produced by electrospinning of MOF blended PAN solution followed by electrospraying of additional MOF nanoparticles. This yielded uniform MOF deposition on nanofibers, occurred due to electrostatic attraction between highly charged nanoparticles and conductive nanofibers. A test bench for real-time CO2 adsorption at room temperature was built with non-dispersive Infrared (NDIR) CO2 sensors. Comparative tests were performed on the membrane to investigate its enhanced adsorption capacity. Three layers of the as-produced membranes displayed CO2 adsorption for approximately 2 h. Thermogravimetric analysis (TGA) of the membrane showed the thermal stability of the MOF and PAN up to 290 and 425 °C, respectively.

Synthesis and Electrospraying of Nanoscale MOF (Metal Organic Framework) for High-Performance CO2 Adsorption Membrane.

PubMed

Wahiduzzaman; Allmond, Kelsey; Stone, John; Harp, Spencer; Mujibur, Khan

2017-12-01

We report the sonochemical synthesis of MOF (metal organic framework) nanoparticles of 30-200 nm in size and electrospraying of those particles on electrospun nanofibers to process a MOF-attached nanofibrous membrane. This membrane displayed significant selectivity towards CO 2 and capacity of adsorbing with 4000-5000 ppm difference from a mixed gas flow of 1% CO 2 and 99% N 2 . Applying ultrasonic waves during the MOF synthesis offered rapid dispersion and formation of crystalline MOF nanoparticles in room temperature. The MOF nanoparticles of 100-200 nm in size displayed higher surface area and adsorption capacity comparing to that of 30-60 nm in size. Nanofibrous membrane was produced by electrospinning of MOF blended PAN solution followed by electrospraying of additional MOF nanoparticles. This yielded uniform MOF deposition on nanofibers, occurred due to electrostatic attraction between highly charged nanoparticles and conductive nanofibers. A test bench for real-time CO 2 adsorption at room temperature was built with non-dispersive Infrared (NDIR) CO 2 sensors. Comparative tests were performed on the membrane to investigate its enhanced adsorption capacity. Three layers of the as-produced membranes displayed CO 2 adsorption for approximately 2 h. Thermogravimetric analysis (TGA) of the membrane showed the thermal stability of the MOF and PAN up to 290 and 425 °C, respectively.

Analysis, Design and Optimization of Non-Cylindrical Fuselage for Blended-Wing-Body (BWB) Vehicle

NASA Technical Reports Server (NTRS)

Mukhopadhyay, V.; Sobieszczanski-Sobieski, J.; Kosaka, I.; Quinn, G.; Charpentier, C.

2002-01-01

Initial results of an investigation towards finding an efficient non-cylindrical fuselage configuration for a conceptual blended-wing-body flight vehicle were presented. A simplified 2-D beam column analysis and optimization was performed first. Then a set of detailed finite element models of deep sandwich panel and ribbed shell construction concepts were analyzed and optimized. Generally these concepts with flat surfaces were found to be structurally inefficient to withstand internal pressure and resultant compressive loads simultaneously. Alternatively, a set of multi-bubble fuselage configuration concepts were developed for balancing internal cabin pressure load efficiently, through membrane stress in inner-stiffened shell and inter-cabin walls. An outer-ribbed shell was designed to prevent buckling due to external resultant compressive loads. Initial results from finite element analysis appear to be promising. These concepts should be developed further to exploit their inherent structurally efficiency.

Glass-ceramic joint and method of joining

DOEpatents

Meinhardt, Kerry D [Richland, WA; Vienna, John D [West Richland, WA; Armstrong, Timothy R [Clinton, TN; Pederson, Larry R [Kennewick, WA

2003-03-18

The present invention is a glass-ceramic material and method of making useful for joining a solid ceramic component and at least one other solid component. The material is a blend of M1-M2-M3, wherein M1 is BaO, SrO, CaO, MgO, or combinations thereof, M2 is Al.sub.2 O.sub.3, present in the blend in an amount from 2 to 15 mol %, M3 is SiO.sub.2 with up to 50 mol % B.sub.2 O.sub.3 that substantially matches a coefficient of thermal expansion of the solid electrolyte. According to the present invention, a series of glass ceramics in the M1-Al.sub.2 O.sub.3 -M3 system can be used to join or seal both tubular and planar solid oxide fuel cells, oxygen electrolyzers, and membrane reactors for the production of syngas, commodity chemicals and other products.

Theoretical calculations of structural, electronic, and elastic properties of CdSe1-x Te x : A first principles study

NASA Astrophysics Data System (ADS)

M, Shakil; Muhammad, Zafar; Shabbir, Ahmed; Muhammad Raza-ur-rehman, Hashmi; M, A. Choudhary; T, Iqbal

2016-07-01

The plane wave pseudo-potential method was used to investigate the structural, electronic, and elastic properties of CdSe1-x Te x in the zinc blende phase. It is observed that the electronic properties are improved considerably by using LDA+U as compared to the LDA approach. The calculated lattice constants and bulk moduli are also comparable to the experimental results. The cohesive energies for pure CdSe and CdTe binary and their mixed alloys are calculated. The second-order elastic constants are also calculated by the Lagrangian theory of elasticity. The elastic properties show that the studied material has a ductile nature.

Extension of lattice cluster theory to strongly interacting, self-assembling polymeric systems.

PubMed

Freed, Karl F

2009-02-14

A new extension of the lattice cluster theory is developed to describe the influence of monomer structure and local correlations on the free energy of strongly interacting and self-assembling polymer systems. This extension combines a systematic high dimension (1/d) and high temperature expansion (that is appropriate for weakly interacting systems) with a direct treatment of strong interactions. The general theory is illustrated for a binary polymer blend whose two components contain "sticky" donor and acceptor groups, respectively. The free energy is determined as an explicit function of the donor-acceptor contact probabilities that depend, in turn, on the local structure and both the strong and weak interactions.

Compositional engineering of acceptors for highly efficient bulk heterojunction hybrid organic solar cells.

PubMed

Amber Yousaf, S; Ikram, M; Ali, S

2018-10-01

The wet chemical synthesis of chromium oxide (Cr 2 O 3 ) nanoparticles (NPs) and its application in active layer of inverted bulk heterojunction organic solar cells is documented in this research. Chromium oxide NPs of 10-30 nm size range having a band gap of 2.9 eV were successfully synthesized. These NPs were used in inverted organic solar cells in amalgamation with P3HT:PCBM and PTB7:PCBM polymers. The fabricated hybrid devices improves PCE significantly for P3HT:PCBM and PTB7:PCBM systems. The photophysical energy levels, optoelectrical properties and microscopic images have been systematically studied for the fabricated devices. The introduction of Cr 2 O 3 nanoparticles (NPs) enhances light harvesting and tunes energy levels into improved electrical parameters. A clear red shift and improved absorption have been observed for ternary blended devices compared to that observed with controlled organic solar cells. Apparently, when the amount of NPs in the binary polymer blend exceeds the required optimum level, there is a breakdown of the bulk heterojunction leading to lowering of the optical and electrical performance of the devices. Copyright © 2018 Elsevier Inc. All rights reserved.

Optical studies of the X-ray transient XTE J2123-058 - II. Phase-resolved spectroscopy

NASA Astrophysics Data System (ADS)

Hynes, R. I.; Charles, P. A.; Haswell, C. A.; Casares, J.; Zurita, C.; Serra-Ricart, M.

2001-06-01

We present time-resolved spectroscopy of the soft X-ray transient XTEJ2123-058 in outburst. A useful spectral coverage of 3700-6700Å was achieved spanning two orbits of the binary, with single-epoch coverage extending to ~9000Å. The optical spectrum approximates a steep blue power law, consistent with emission on the Rayleigh-Jeans tail of a hot blackbody spectrum. The strongest spectral lines are Heii 4686Å and Ciii/Niii 4640Å (Bowen blend) in emission. Their relative strengths suggest that XTEJ2123-058 was formed in the Galactic plane, not in the halo. Other weak emission lines of Heii and Civ are present, and Balmer lines show a complex structure, blended with Heii. Heii 4686-Å profiles show a complex multiple S-wave structure, with the strongest component appearing at low velocities in the lower-left quadrant of a Doppler tomogram. Hα shows transient absorption between phases 0.35 and 0.55. Both of these effects appear to be analogous to similar behaviour in SW Sex type cataclysmic variables. We therefore consider whether the spectral line behaviour of XTEJ2123-058 can be explained by the same models invoked for those systems.

An Experimental Investigation on the Effect of Addition of Ternary Blend on the Mix Design Characteristics of High Strength Concrete using Steel Fibre

NASA Astrophysics Data System (ADS)

Sinha, Deepa A., Dr; Verma, A. K., Dr

2017-08-01

This paper presents the results of M60 grade of concrete. M60 grade of concrete is achieved by maximum density technique. Concrete is brittle and weak in tension and develops cracks during curing and due to thermal expansion / contraction over a period ot time. Thus the effect of addition of 1% steel fibre is studied. For ages, concrete has been one of the widely used materials for construction. When cement is manufactured, every one ton of cement produces around one ton of carbon dioxide leading to global warming and also as natural resources are finishing, so use of supplementary cementitious material like alccofine and flyash is used as partial replacement of cement is considered. The effect of binary and ternary blend on the strength characteristics is studied. The results indicate that the concrete made with alccofine and flyash generally show excellent fresh and hardened properties. The ternary system that is Portland cement-fly ash-Alccofine concrete was found to increase the strength of concrete when compared to concrete made with Portland cement or even from Portland cement and fly ash.

Microstructures of GaN1-xPx layers grown on (0001) GaN substrates by gas source molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Seong, Tae-Yeon; Bae, In-Tae; Choi, Chel-Jong; Noh, D. Y.; Zhao, Y.; Tu, C. W.

1999-03-01

Transmission electron microscope (TEM), transmission electron diffraction (TED), and synchrotron x-ray diffraction (XRD) studies have been performed to investigate microstructural behavior of gas source molecular beam epitaxial GaN1-xPx layers grown on (0001) GaN/sapphire at temperatures (Tg) in the range 500-760 °C. TEM, TED, and XRD results indicate that the samples grown at Tg⩽600 °C undergo phase separation resulting in a mixture of GaN-rich and GaP-rich GaNP with zinc-blende structure. However, the samples grown at Tg⩾730 °C are found to be binary zinc-blende GaN(P) single crystalline materials. As for the 500 °C layer, the two phases are randomly oriented and distributed, whereas the 600 °C layer consists of phases that are elongated and inclined by 60°-70° clockwise from the [0001]α-GaN direction. The samples grown at Tg⩾730 °C are found to consist of two types of microdomains, namely, GaN(P)I and GaN(P)II; the former having twin relation to the latter.

Do Membranes Dream of Electric Tubes? Advanced Membranes Using Carbon Nanotube - Polymer Nanocomposites

NASA Astrophysics Data System (ADS)

de Lannoy, Charles-Francois Pedro Claude Karolek Ghislain

Membrane technologies represent an energy efficient, effective solution for treating municipal and commercial waters/wastewaters. Membranes are predominantly polymer-based and despite steady advances in polymeric materials, they continue to suffer from operational problems including biofouling and breakages. This work addresses these two disparate problems by developing novel CNT-polymer nanocomposite materials that contain variously functionalized carbon nanotubes (fCNTs) in low quantities (<0.5wt%). Several strategies have been employed to achieve highly functional CNT-polymer nanocomposite membranes including blend mixing, ionic charge association, and covalent cross-linking with monomer and oligomer constituents. These CNT-polymer nanocomposite membranes were compared to traditional polymer membranes across various properties including increased Young's Modulus, changes in surface hydrophilicity, fine control over molecular weight cut-off and flux, and surface electrical conductivity. Membranes with high surface electrical conductivity were further tested for their anti-biofouling properties. Finally, CNT stability and polymer compatibility were evaluated throughout membrane manufacture, use, and cleaning. The incorporation of CNTs mixed in bulk phase and linked through ionic associations in polymer matrices showed significant (50%) increases in Young's modulus for certain CNT functionalizations and derivatization percent. Membranes formed with high surface electrical conductivity demonstrated almost complete resistance to biofouling (> 95%) in long-term bacterially challenged experiments. CNTs and polymer mixtures that lacked covalent or ionic bonds were susceptible to significant (up to 10%) loss of CNTs during membrane non-solvent gelation and aggressive chemical cleaning treatment. Functionalized carbon nanotubes endow polymer membranes with their unique strength and electrically conductive properties. These added properties were demonstrated to greatly improve membrane operational efficiency and membrane longevity. CNT-polymer nanocomposite membranes offer low-energy, high-efficiency, and long-lifetime alternatives to traditional polymer membranes. With further advances in polymeric nanomaterials, membrane technology has the potential for wide applicability across many fields outside of water filtration and desalination.

Dermal-epidermal membrane systems by using human keratinocytes and mesenchymal stem cells isolated from dermis.

PubMed

Salerno, Simona; Messina, Antonietta; Giordano, Francesca; Bader, Augustinus; Drioli, Enrico; De Bartolo, Loredana

2017-02-01

Dermal-epidermal membrane systems were developed by co-culturing human keratinocytes with Skin derived Stem Cells (SSCs), which are Mesenchymal Stem Cells (MSCs) isolated from dermis, on biodegradable membranes of chitosan (CHT), polycaprolactone (PCL) and a polymeric blend of CHT and PCL. The membranes display physico-chemical, morphological, mechanical and biodegradation properties that could satisfy and fulfil specific requirements in skin tissue engineering. CHT membrane exhibits an optimal biodegradation rate for acute wounds; CHT-PCL for the chronic ones. On the other hand, PCL membrane in spite of its very slow biodegradation rate exhibits mechanical properties similar to in vivo dermis, a lower hydrophilic character, and a surface roughness, all properties that make it able to sustain cell adhesion and proliferation for in vitro skin models. Both CHT-PCL and PCL membranes guided epidermal and dermal differentiation of SSCs as pointed out by the expression of cytokeratins and the deposition of the ECM protein fibronectin, respectively. In the dermal-epidermal membrane systems, a more suitable microenvironment for the SSCs differentiation was promoted by the interactions and the mutual interplay with keratinocytes. Being skin tissue-biased stem cells committed to their specific final dermal and/or epidermal cell differentiation, SSCs are more suitable for skin tissue engineering than other adult MSCs with different origin. For this reason, they represent a useful autologous cell source for engineering skin substitutes for both in vivo and in vitro applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Microporous Poly(L-Lactic Acid) Membranes Fabricated by Polyethylene Glycol Solvent-Cast/Particulate Leaching Technique

PubMed Central

Selvam, Shivaram; Chang, Wenji V.; Nakamura, Tamako; Samant, Deedar M.; Thomas, Padmaja B.; Trousdale, Melvin D.; Mircheff, Austin K.; Schechter, Joel E.

2009-01-01

With the eventual goal of developing a tissue-engineered tear secretory system, we found that primary lacrimal gland acinar cells grown on solid poly(L-lactic acid) (PLLA) supports expressed the best histiotypic morphology. However, to be able to perform vectorial transport functions, epithelia must be supported by a permeable substratum. In the present study, we describe the use of a solvent-cast/particulate leaching technique to fabricate microporous PLLA membranes (mpPLLAm) from PLLA/polyethylene glycol blends. Scanning electron microscopy revealed pores on both the air-cured (∼4 μm) and glass-cured sides (<2 μm) of the mpPLLAm. Diffusion studies were performed with mpPLLAm fabricated from 57.1% PLLA/42.9% polyethylene glycol blends to confirm the presence of channelized pores. The data reveal that glucose, L-tryptophan, and dextran (a high molecular weight glucose polymer) readily permeate mpPLLAm. Diffusion of the immunoglobulin G through the mpPLLAm decreased with time, suggesting the possible adsorption and occlusion of the pores. Cells cultured on the mpPLLAm (57.1/42.9 wt%) grew to subconfluent monolayers but retained histiotypic morphological and physiological characteristics of lacrimal acinar cells in vivo. Our results suggest that mpPLLAm fabricated using this technique may be useful as a scaffold for a bioartificial lacrimal gland device. PMID:19260769

Amphipathic peptide affects the lateral domain organization of lipid bilayers.

PubMed

Polozov, I V; Polozova, A I; Molotkovsky, J G; Epand, R M

1997-09-04

Using lipid-specific fluorescent probes, we studied the effects of amphipathic helical, membrane active peptides of the A- and L-type on membrane domain organization. In zwitterionic binary systems composed of mixtures of phosphatidylcholine and phosphatidylethanolamine, both types of peptides associated with the fluid phase. While binding with high affinity to fluid membranes, peptides were unable to penetrate into the lipid membrane in the gel state. If trapped kinetically by cooling from the fluid phase, peptides dissociated from the gel membrane on the time scale of several hours. While the geometrical shape of the alpha-helical peptides determines their interactions with membranes with non-bilayer phase propensity, the shape complementarity mechanism by itself is unable to induce lateral phase separation in a fluid membrane. Charge-charge interactions are capable of inducing lateral domain formation in fluid membranes. Both peptides had affinity for anionic lipids which resulted in about 30% enrichment of acidic lipids within several nanometers of the peptide's tryptophan, but there was no long-range order in peptide-induced lipid demixing. Peptide insertion in fluid acidic membranes was accompanied by only a small increase in bilayer surface and a decrease in polarity in the membrane core. Peptide-lipid charge-charge interactions were also capable of modulating existing domain composition in the course of the main phase transition in mixtures of anionic phosphatidylglycerol with zwitterionic phosphatidylcholine.

[Computer modeling the dependences of the membrane potential for polymeric membrane separated non-homogeneous electrolyte solutions on concentration Rayleigh number].

PubMed

Slezak, Izabella H; Jasik-Slezak, Jolanta; Bilewicz-Wyrozumska, Teresa; Slezak, Andrzej

2006-01-01

On the basis of model equation describing the membrane potential delta psi(s) on concentration Rayleigh number (R(C)), mechanical pressure difference (deltaP), concentration polarization coefficient (zeta s) and ratio concentration of solutions separated by membrane (Ch/Cl), the characteristics delta psi(s) = f(Rc)(delta P, zeta s, Ch/Cl) for steady values of zeta s, R(C) and Ch/Cl in single-membrane system were calculated. In this system neutral and isotropic polymeric membrane oriented in horizontal plane, the non-homogeneous binary electrolytic solutions of various concentrations were separated. Nonhomogeneity of solutions is results from creations of the concentration boundary layers on both sides of the membrane. Calculations were made for the case where on a one side of the membrane aqueous solution of NaCl at steady concentration 10(-3) mol x l(-1) (Cl) was placed and on the other aqueous solutions of NaCl at concentrations from 10(-3) mol x l(-1) to 2 x 10(-2) mol x l(-1) (Ch). Their densities were greater than NaCl solution's at 10(-3) mol x l(-1). It was shown that membrane potential depends on hydrodynamic state of a complex concentration boundary layer-membrane-concentration boundary layer, what is controlled by deltaP, Ch/Cl, Rc and Zeta(s).

White Polymer Light-Emitting Diodes Based on Exciplex Electroluminescence from Polymer Blends and a Single Polymer.

PubMed

Liang, Junfei; Zhao, Sen; Jiang, Xiao-Fang; Guo, Ting; Yip, Hin-Lap; Ying, Lei; Huang, Fei; Yang, Wei; Cao, Yong

2016-03-09

In this Article, we designed and synthesized a series of polyfluorene derivatives, which consist of the electron-rich 4,4'-(9-alkyl-carbazole-3,6-diyl)bis(N,N-diphenylaniline) (TPA-Cz) in the side chain and the electron-deficient dibenzothiophene-5,5-dioxide (SO) unit in the main chain. The resulting copolymer PF-T25 that did not comprise the SO unit exhibited blue light-emission with the Commission Internationale de L'Eclairage coordinates of (0.16, 0.10). However, by physically blending PF-T25 with a blue light-emitting SO-based oligomer, a novel low-energy emission correlated to exciplex emerged due to the appropriate energy level alignment of TPA-Cz and the SO-based oligomers, which showed extended exciton lifetime as confirmed by time-resolved photoluminescent spectroscopy. The low-energy emission was also identified in copolymers consisting of SO unit in the main chain, which can effectively compensate for the high-energy emission to produce binary white light-emission. Polymer light-emitting diodes based on the exciplex-type single greenish-white polymer exhibit the peak luminous efficiency of 2.34 cd A(-1) and the maximum brightness of 12 410 cd m(-2), with Commission Internationale de L'Eclairage color coordinates (0.27, 0.39). The device based on such polymer showed much better electroluminescent stability than those based on blending films. These observations indicated that developing a single polymer with the generated exciplex emission can be a novel and effective molecular design strategy toward highly stable and efficient white polymer light-emitting diodes.

Improvement of PET surface hydrophilicity and roughness through blending

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kolahchi, Ahmad Rezaei; Ajji, Abdellah; Carreau, Pierre J.

Controlling the adhesion of the polymer surface is a key issue in surface science, since polymers have been a commonly used material for many years. The surface modification in this study includes two different aspects. One is to enhance the hydrophilicity and the other is to create the roughness on the PET film surface. In this study we developed a novel and simple approach to modify polyethylene terephthalate (PET) film surface through polymer blending in twin-screw extruder. One example described in the study uses polyethylene glycol (PEG) in polyethylene terephthalate (PET) host to modify a PET film surface. Low contentmore » of polystyrene (PS) as a third component was used in the system to increase the rate of migration of PEG to the surface of the film. Surface enrichment of PEG was observed at the polymer/air interface of the polymer film containing PET-PEG-PS whereas for the PET-PEG binary blend more PEG was distributed within the bulk of the sample. Furthermore, a novel method to create roughness at the PET film surface was proposed. In order to roughen the surface of PET film, a small amount of PKHH phenoxy resin to change PS/PET interfacial tension was used. The compatibility effect of PKHH causes the formation of smaller PS droplets, which were able to migrate more easily through PET matrix. Consequently, resulting in a locally elevated concentration of PS near the surface of the film. The local concentration of PS eventually reached a level where a co-continuous morphology occurred, resulting in theinstabilities on the surface of the film.« less

MnO2 nanosheet mediated "DD-A" FRET binary probes for sensitive detection of intracellular mRNA.

PubMed

Ou, Min; Huang, Jin; Yang, Xiaohai; Quan, Ke; Yang, Yanjing; Xie, Nuli; Wang, Kemin

2017-01-01

The donor donor-acceptor (DD-A) FRET model has proven to have a higher FRET efficiency than donor-acceptor acceptor (D-AA), donor-acceptor (D-A), and donor donor-acceptor acceptor (DD-AA) FRET models. The in-tube and in-cell experiments clearly demonstrate that the "DD-A" FRET binary probes can indeed increase the FRET efficiency and provide higher imaging contrast, which is about one order of magnitude higher than the ordinary "D-A" model. Furthermore, MnO 2 nanosheets were employed to deliver these probes into living cells for intracellular TK1 mRNA detection because they can adsorb ssDNA probes, penetrate across the cell membrane and be reduced to Mn 2+ ions by intracellular GSH. The results indicated that the MnO 2 nanosheet mediated "DD-A" FRET binary probes are capable of sensitive and selective sensing gene expression and chemical-stimuli changes in gene expression levels in cancer cells. We believe that the MnO 2 nanosheet mediated "DD-A" FRET binary probes have the potential as a simple but powerful tool for basic research and clinical diagnosis.

Clostridial Binary Toxins: Basic Understandings that Include Cell Surface Binding and an Internal "Coup de Grâce".

PubMed

Stiles, Bradley G

2017-01-01

Clostridium species can make a remarkable number of different protein toxins, causing many diverse diseases in humans and animals. The binary toxins of Clostridium botulinum, C. difficile, C. perfringens, and C. spiroforme are one group of enteric-acting toxins that attack the actin cytoskeleton of various cell types. These enterotoxins consist of A (enzymatic) and B (cell binding/membrane translocation) components that assemble on the targeted cell surface or in solution, forming a multimeric complex. Once translocated into the cytosol via endosomal trafficking and acidification, the A component dismantles the filamentous actin-based cytoskeleton via mono-ADP-ribosylation of globular actin. Knowledge of cell surface receptors and how these usurped, host-derived molecules facilitate intoxication can lead to novel ways of defending against these clostridial binary toxins. A molecular-based understanding of the various steps involved in toxin internalization can also unveil therapeutic intervention points that stop the intoxication process. Furthermore, using these bacterial proteins as medicinal shuttle systems into cells provides intriguing possibilities in the future. The pertinent past and state-of-the-art present, regarding clostridial binary toxins, will be evident in this chapter.

Solubilization of lipids and lipid phases by the styrene-maleic acid copolymer.

PubMed

Dominguez Pardo, Juan J; Dörr, Jonas M; Iyer, Aditya; Cox, Ruud C; Scheidelaar, Stefan; Koorengevel, Martijn C; Subramaniam, Vinod; Killian, J Antoinette

2017-01-01

A promising tool in membrane research is the use of the styrene-maleic acid (SMA) copolymer to solubilize membranes in the form of nanodiscs. Since membranes are heterogeneous in composition, it is important to know whether SMA thereby has a preference for solubilization of either specific types of lipids or specific bilayer phases. Here, we investigated this by performing partial solubilization of model membranes and analyzing the lipid composition of the solubilized fraction. We found that SMA displays no significant lipid preference in homogeneous binary lipid mixtures in the fluid phase, even when using lipids that by themselves show very different solubilization kinetics. By contrast, in heterogeneous phase-separated bilayers, SMA was found to have a strong preference for solubilization of lipids in the fluid phase as compared to those in either a gel phase or a liquid-ordered phase. Together the results suggest that (1) SMA is a reliable tool to characterize native interactions between membrane constituents, (2) any solubilization preference of SMA is not due to properties of individual lipids but rather due to properties of the membrane or membrane domains in which these lipids reside and (3) exploiting SMA resistance rather than detergent resistance may be an attractive approach for the isolation of ordered domains from biological membranes.

Anti-fouling and high water permeable forward osmosis membrane fabricated via layer by layer assembly of chitosan/graphene oxide

NASA Astrophysics Data System (ADS)

Salehi, Hasan; Rastgar, Masoud; Shakeri, Alireza

2017-08-01

To date, forward osmosis (FO) has received considerable attention due to its potential application in seawater desalination. FO does not require external hydraulic pressure and consequently is believed to have a low fouling propensity. Despite the numerous privileges of FO process, a major challenge ahead for its development is the lack of high performance membranes. In this study, we fabricated a novel highly-efficient FO membrane using layer-by-layer (LbL) assembly of positive chitosan (CS) and negative graphene oxide (GO) nanosheets via electrostatic interaction on a porous support layer. The support layer was prepared by blending hydrophilic sulfonated polyethersulfone (SPES) into polyethersulfone (PES) matrix using wet phase inversion process. Various characterization techniques were used to confirm successful fabrication of LbL membrane. The number of layers formed on the SPES-PES support layer was easily adjusted by repeating the CS and GO deposition cycles. Thin film composite (TFC) membrane was also prepared by the same SPES-PES support layer and polyamide (PA) active layer to compare membranes performances. The water permeability and salt rejection of the fabricated membranes were obtained by two kinds of draw solutions (including Na2SO4 and sucrose) under two different membrane orientations. The results showed that membrane coated by a CS/GO bilayers had water flux of 2-4 orders of magnitude higher than the TFC one. By increasing the number of CS/GO bilayers, the selectivity of the LbL membrane was improved. The novel fabricated LbL membrane showed better fouling resistance than the TFC one in the feed solution containing 200 ppm of sodium alginate as a foulant model.

Binary Polymer Brushes of Strongly Immiscible Polymers.

PubMed

Chu, Elza; Babar, Tashnia; Bruist, Michael F; Sidorenko, Alexander

2015-06-17

The phenomenon of microphase separation is an example of self-assembly in soft matter and has been observed in block copolymers (BCPs) and similar materials (i.e., supramolecular assemblies (SMAs) and homo/block copolymer blends (HBCs)). In this study, we use microphase separation to construct responsive polymer brushes that collapse to generate periodic surfaces. This is achieved by a chemical reaction between the minor block (10%, poly(4-vinylpyridine)) of the block copolymer and a substrate. The major block of polystyrene (PS) forms mosaic-like arrays of grafted patches that are 10-20 nm in size. Depending on the nature of the assembly (SMA, HBC, or neat BCP) and annealing method (exposure to vapors of different solvents or heating above the glass transition temperature), a range of "mosaic" brushes with different parameters can be obtained. Successive grafting of a secondary polymer (polyacrylamide, PAAm) results in the fabrication of binary polymer brushes (BPBs). Upon being exposed to specific selective solvents, BPBs may adopt different conformations. The surface tension and adhesion of the binary brush are governed by the polymer occupying the top stratum. The "mosaic" brush approach allows for a combination of strongly immiscible polymers in one brush. This facilitates substantial contrast in the surface properties upon switching, previously only possible for substrates composed of predetermined nanostructures. We also demonstrate a possible application of such PS/PAAm brushes in a tunable bioadhesion-bioadhesive (PS on top) or nonbioadhesive (PAAm on top) surface as revealed by Escherichia coli bacterial seeding.

Study of binary and ternary organic hybrid CdSe quantum dot photodetector

NASA Astrophysics Data System (ADS)

Ramar, M.; Kajal, S.; Pal, Prabir; Srivastava, R.; Suman, C. K.

2015-09-01

The hybrid binary and ternary photodetectors (PDs) were fabricated from P3HT-PC71BM with CdSe quantum dot (QD) materials. The absorption spectra of P3HT:PC71BM (named as B1), P3HT:CdSe (B2) and P3HT:CdSe:PC71BM (T) active blended material were analyzed in the wavelength range from 350 to 800 nm. The current density-voltage characteristics of the device were measured in dark and under illumination for study of detector detectivities and the contact with electrode. The ratio at -0.5 V for PDs B1, B2 and T is 1.1 × 102, 1.9 × 102 and 1.8 × 103, respectively. The values of detectivity for B1, B2 and T are 1 × 1010, 2 × 1010 and 7 × 1011 Jones, respectively. The for PD T is ten times in comparison with B1 and B2 PDs. The linear dynamic range (LDR) value for ternary device is more than double to both binary PDs. The absorption by CdSe QD increases the photon efficiency in the ternary detector, and at the same time the ternary detectors have high detectivity in broad spectral range. The responsivity of current to the light intensity exponent θ for detector B1, B2 and T is ~0.55, 0.55 and 0.62, respectively, which represents a complex process of electron hole generation, recombination and trapping within active material.

Rejecting Astrophysical False Positives from the TrES Transiting Planet Survey: The Example of GSC 03885-00829

NASA Astrophysics Data System (ADS)

O'Donovan, Francis T.; Charbonneau, David; Torres, Guillermo; Mandushev, Georgi; Dunham, Edward W.; Latham, David W.; Alonso, Roi; Brown, Timothy M.; Esquerdo, Gilbert A.; Everett, Mark E.; Creevey, Orlagh L.

2006-06-01

Ground-based wide-field surveys for nearby transiting gas giants are yielding far fewer true planets than astrophysical false positives, some of which are difficult to reject. Recent experience has highlighted the need for careful analysis to eliminate astronomical systems in which light from a faint eclipsing binary is blended with that from a bright star. During the course of the Transatlantic Exoplanet Survey, we identified a system presenting a transit-like periodic signal. We obtained the proper motion and infrared color of this target (GSC 03885-00829) from publicly available catalogs, which suggested this star is an F dwarf, supporting our transit hypothesis. This spectral classification was confirmed using spectroscopic observations from which we determined the stellar radial velocity. The star did not exhibit any signs of a stellar mass companion. However, subsequent multicolor photometry displayed a color-dependent transit depth, indicating that a blend was the likely source of the eclipse. We successfully modeled our initial photometric observations of GSC 03885-00829 as the light from a K dwarf binary system superimposed on the light from a late F dwarf star. High-dispersion spectroscopy confirmed the presence of light from a cool stellar photosphere in the spectrum of this system. With this candidate, we demonstrate both the difficulty in identifying certain types of false positives in a list of candidate transiting planets and our procedure for rejecting these imposters, which may be useful to other groups performing wide-field transit surveys. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

Preparation of PVDF/SiO2 composite membrane for salty oil emulsion separation: Physicochemical properties changes and its impact on fouling propensity

NASA Astrophysics Data System (ADS)

Ngang, H. P.; Ahmad, A. L.; Low, S. C.; Ooi, B. S.

2017-06-01

In this study, polyvinylidene fluoride (PVDF)/silica (SiO2) composite membranes were prepared by diffusion induced phase separation through direct blending method. The roles of SiO2 particles concentration on membrane physicochemical properties were evaluated through oil emulsion separation under high ionic strength environment whereby hydrophobic interaction is prevalent. Membranes were characterized using field emission scanning electron microscope (FESEM), atomic force microscopy (AFM), contact angle measurement, membrane porosity and pore size distribution. It was expected that by adding the monodispersed SiO2, it will render the membrane with hydrophilic characteristic. However, it is concomitantly changing the physical properties of the membrane. Addition of SiO2 caused the changes to the physicochemical properties of the composite membrane and its effects on the fouling propensity were evaluated. It was found that the mean pore size of the membranes increased with the increase of SiO2 concentration. The addition of hydrophilic SiO2 had accelerated the precipitation of the membrane dope solution resulting in changes of membrane cross section morphology. FESEM images showed the membrane cross-section morphology of PVDF/SiO2 composite membrane had gradually changed from finger-like to macrovoid-like structure with the increased of SiO2 concentration. The hydrophilicity of the PVDF/SiO2 composite membrane was enhanced which is a desired property for water purification. However, the changes in physical properties (pore size, porosity, and surface roughness) had played more dominant role in the oil emulsion fouling behaviour rather than hydrophilicity enhancement. Due to the salting out effect under high ionic strength environment, hydrophobic interaction played an important role in the oil adsorption. The increment in membrane pore size, porosity, and surface roughness after incorporation of SiO2 particles had encountered more serious relative flux reduction and lower flux recovery ratio.

Hydrocarbon-Based Polymer Electrolyte Membranes: Importance of Morphology on Ion Transport and Membrane Stability.

PubMed

Shin, Dong Won; Guiver, Michael D; Lee, Young Moo

2017-03-22

A fundamental understanding of polymer microstructure is important in order to design novel polymer electrolyte membranes (PEMs) with excellent electrochemical performance and stabilities. Hydrocarbon-based polymers have distinct microstructure according to their chemical structure. The ionic clusters and/or channels play a critical role in PEMs, affecting ion conductivity and water transport, especially at medium temperature and low relative humidity (RH). In addition, physical properties such as water uptake and dimensional swelling behavior depend strongly on polymer morphology. Over the past few decades, much research has focused on the synthetic development and microstructural characterization of hydrocarbon-based PEM materials. Furthermore, blends, composites, pressing, shear field, electrical field, surface modification, and cross-linking have also been shown to be effective approaches to obtain/maintain well-defined PEM microstructure. This review summarizes recent work on developments in advanced PEMs with various chemical structures and architecture and the resulting polymer microstructures and morphologies that arise for potential application in fuel cell, lithium ion battery, redox flow battery, actuators, and electrodialysis.

A Study of influence on sulfonated TiO2-Poly (Vinylidene fluoride-co-hexafluoropropylene) nano composite membranes for PEM Fuel cell application

NASA Astrophysics Data System (ADS)

kumar, K. Selva; Rajendran, S.; Prabhu, M. Ramesh

2017-10-01

The present work describes the sulfonated Titania directly blended with Poly (Vinylidene fluoride-co-hexafluoropropylene) as a host polymer by solvent casting technique for PEM fuel cell application. Characterization studies such as FT-IR, SEM, EDX, AFM, Proton conductivity, contact angle measurement, IEC, TG, water uptake, tensile strength were performed by for synthesized proton conducting polymer electrolytes. The maximum proton conductivity value was found to be 3.6 × 10-3S/cm for 25 wt% sulfonated Titania based system at 80 °C. The temperature dependent proton conductivity of the polymer electrolyte follows an Arrhenius relationship. Surface morphology of the composite membranes was investigated by tapping mode. Thermal stability of the system was studied by TG analysis. The fabricated composite membranes with high proton conductivity, good water uptake and IEC parameters exhibited a maximum fuel cell power density of 85 Mw/cm2for PEM fuel cell application.

High throughput study of fuel cell proton exchange membranes: Poly(vinylidene fluoride)/acrylic polyelectrolyte blends and nanocomposites with zirconium

NASA Astrophysics Data System (ADS)

Zapata B., Pedro Jose

Sustainability is perhaps one of the most heard buzzwords in the post-20 th century society; nevertheless, it is not without a reason. Our present practices for energy supply are largely unsustainable if we consider their environmental and social impact. In view of this unfavorable panorama, alternative sustainable energy sources and conversion approaches have acquired noteworthy significance in recent years. Among these, proton exchange membrane fuel cells (PEMFCs) are being considered as a pivotal building block in the transition towards a sustainable energy economy in the 21st century. The polyelectrolyte membrane or proton exchange membrane (PEM) is a vital component, as well as a performance-limiting factor, of the PEMFC. Consequently, the development of high-performance PEM materials is of utmost importance for the advance of the PEMFC field. In this work, alternative PEM materials based on semi-interpenetrated networks from blends of poly(vinyledene fluoride) (PVDF) (inert phase) and sulfonated crosslinked acrylic polyelectrolytes (PE) (proton-conducting phase), as well as tri-phase PVDF/PE/zirconium-based composites, are studied. To alleviate the burden resulting from the vast number of possible combinations of the different precursors utilized in the preparation of the membranes (PVDF: 5x, PE: 2x, Nanoparticle: 3x), custom high-throughput (HT) screening systems have been developed for their characterization. By coupling the data spaces obtained via these systems with the appropriate statistical and data analysis tools it was found that, despite not being directly involved in the proton transport process, the inert PVDF phase plays a major role on proton conductivity. Particularly, a univocal inverse correlation between the PVDF crystalline characteristics (i.e., crystallinity and crystallite size) and melt viscosity, and membrane proton conductivity was discovered. Membranes based on highly crystalline and viscous PVDF homopolymers exhibited reduced proton conductivity due to precluded segmental motion and physical blockage of the PE chains during crosslinking. In addition, a maximum effective amount of PE (55-60wt%, neutralized form) beneficial for proton conductivity was revealed. Some of the aforementioned effects may possibly have been overlooked if a high-throughput study including plentiful combinations of multiple precursors hadn't been performed. In the case of composite membranes, despite the fact that nanoparticle dispersion was thermodynamically limited, a general improvement in proton conductivity was evidenced at low to medium nanoparticle loadings (0.5 to 1wt%) in comparison to non-hybrid PVDF/PE references. This beneficial effect was particularly noticeable in membranes based on PVDF homopolymers (7% to 14.3% increment), where the nanoparticles induced a "healing" effect by providing proton-conducting paths between non-crosslinked PE channels separated by dense PVDF areas resulting from large PVDF crystallites. In general, the results presented herein are promising for the development of new cost-effective alternative PEMs.

Cellulosic Biomass-Reinforced Polyvinylidene Fluoride Separators with Enhanced Dielectric Properties and Thermal Tolerance.

PubMed

Li, Lei; Yu, Miao; Jia, Chao; Liu, Jianxin; Lv, Yanyan; Liu, Yanhua; Zhou, Yi; Liu, Chuanting; Shao, Ziqiang

2017-06-21

Safety issues are critical barriers to large-scale energy storage applications of lithium-ion batteries (LIBs). Using an ameliorated, thermally stable, shutdown separator is an effective method to overcome the safety issues. Herein, we demonstrate a novel, cellulosic biomass-material-blended polyvinylidene fluoride separator that was prepared using a simple nonsolvent-induced phase separation technique. This process formed a microporous composite separator with reduced crystallinity, uniform pore size distribution, superior thermal tolerance, and enhanced electrolyte wettability and dielectric and mechanical properties. In addition, the separator has a superior capacity retention and a better rate capability compared to the commercialized microporous polypropylene membrane. This fascinating membrane was fabricated via a relatively eco-friendly and cost-effective method and is an alternative, promising separator for high-power LIBs.

Electrospinning of PLGA/gum tragacanth nanofibers containing tetracycline hydrochloride for periodontal regeneration.

PubMed

Ranjbar-Mohammadi, Marziyeh; Zamani, M; Prabhakaran, M P; Bahrami, S Hajir; Ramakrishna, S

2016-01-01

Controlled drug release is a process in which a predetermined amount of drug is released for longer period of time, ranging from days to months, in a controlled manner. In this study, novel drug delivery devices were fabricated via blend electrospinning and coaxial electrospinning using poly lactic glycolic acid (PLGA), gum tragacanth (GT) and tetracycline hydrochloride (TCH) as a hydrophilic model drug in different compositions and their performance as a drug carrier scaffold was evaluated. Scanning electron microscopy (SEM) results showed that fabricated PLGA, blend PLGA/GT and core shell PLGA/GT nanofibers had a smooth and bead-less morphology with the diameter ranging from 180 to 460 nm. Drug release studies showed that both the fraction of GT within blend nanofibers and the core-shell structure can effectively control TCH release rate from the nanofibrous membranes. By incorporation of TCH into core-shell nanofibers, drug release was sustained for 75 days with only 19% of burst release within the first 2h. The prolonged drug release, together with proven biocompatibility, antibacterial and mechanical properties of drug loaded core shell nanofibers make them a promising candidate to be used as drug delivery system for periodontal diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

Biohybrid Fibro-Porous Vascular Scaffolds: Effect of Crosslinking on Properties

PubMed Central

Nozik, Danna; Patel, Harsh; Singh, Raj K.; Vohra, Yogesh K.

2015-01-01

Tubular grafts were fabricated from blends of polycaprolactone (PCL) and poly(glycolide -co-caprolactone) (PGC) polymers and coated with an extracellular matrix containing collagens, laminin, and proteoglycans, but not growth factors (HuBiogel™). Multifunctional scaffolds from polymer blends and membrane proteins provide the necessary biomechanics and biological functions for tissue regeneration. Two crosslinking agents, a natural crosslinker namely genipin (Gp) and a carbodiimide reagent namely 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), were used for further stabilizing the protein matrix and the effect of crosslinking was evaluated for structural, morphological, mechanical properties using SEM, DSC and DMA. SEM images and fiber diameter distribution showed fiber-size between 0.2 µm to 1 µm with the majority of fiber diameters being under 500 nm, indicating upper range of protein fiber-sizes (for example, collagen fibers in extracellular matrix are in 50 to 500 nm diameter range). HB coating did not affect the mechanical properties, but increased its hydrophilicity of the graft. Overall data showed that PCL/PGC blends with 3:1 mass ratio exhibited mechanical properties comparable to those of human native arteries (tensile strength of 1–2 MPa and Young’s modulus of <10 MPa). Additionally, the effect of crosslinking on coating stability was investigated to assure the retention of proteins on scaffold for effective cell-matrix interactions. PMID:26082566

Biohybrid Fibro-Porous Vascular Scaffolds: Effect of Crosslinking on Properties.

PubMed

Thomas, Vinoy; Nozik, Danna; Patel, Harsh; Singh, Raj K; Vohra, Yogesh K

Tubular grafts were fabricated from blends of polycaprolactone (PCL) and poly(glycolide -co-caprolactone) (PGC) polymers and coated with an extracellular matrix containing collagens, laminin, and proteoglycans, but not growth factors (HuBiogel™). Multifunctional scaffolds from polymer blends and membrane proteins provide the necessary biomechanics and biological functions for tissue regeneration. Two crosslinking agents, a natural crosslinker namely genipin (Gp) and a carbodiimide reagent namely 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), were used for further stabilizing the protein matrix and the effect of crosslinking was evaluated for structural, morphological, mechanical properties using SEM, DSC and DMA. SEM images and fiber diameter distribution showed fiber-size between 0.2 µm to 1 µm with the majority of fiber diameters being under 500 nm, indicating upper range of protein fiber-sizes (for example, collagen fibers in extracellular matrix are in 50 to 500 nm diameter range). HB coating did not affect the mechanical properties, but increased its hydrophilicity of the graft. Overall data showed that PCL/PGC blends with 3:1 mass ratio exhibited mechanical properties comparable to those of human native arteries (tensile strength of 1-2 MPa and Young's modulus of <10 MPa). Additionally, the effect of crosslinking on coating stability was investigated to assure the retention of proteins on scaffold for effective cell-matrix interactions.

A Study on Anti – Fouling Behaviour and Mechanical Properties of PVA/Chitosan/TEOS Hybrid membrane in The Treatment of Copper Solution

NASA Astrophysics Data System (ADS)

Sulaiman, N. A.; Kassim Shaari, N. Z.; Rahman, N. Abdul

2018-05-01

In a wastewater treatment by using membrane filtration, fouling has been one of the major problems. In this study, the anti-fouling behaviour of the fabricated thin-film composite membrane were studied during the treatment of water containing copper ion. The membranes were prepared from a polymer blend of 2wt.% chitosan with 10 wt.% poly(vinyl alcohol) (PVA) and then it was cross – linked with tetraethylorthosilicate (TEOS) through sol-gel method. The membrane had been evaluated for its resistance against organic fouling where humic acid had been chosen as organic foulant model which represent the natural organic matter (NOM) in water or wastewater. The dead-end filtration experiments were carried out by using 50 ppm of copper solution with and without the presence of humic acid as feed solution, which was passed through two types of thin film composite membranes. The possible reversible fouling was evaluated by using relative flux decay (RFD) and relative flux recovery (RFR) calculations. The percentage of copper ion removal was evaluated by using Atomic Absorption Spectroscopy (AAS). Based on the results, with the presence of humic acid, the membrane incorporated with silica precursor (TEOS) showed lower flux decay (3%) and higher flux recovery (76%), which show that the formulated hybrid membrane possesses the anti fouling property. The same trend was observed in the mechanical properties of hybrid membrane, where the presence of TEOS has improved the tensile strength and flexibility of the membrane. Therefore, the fabricated thin film composite with the anti-fouling properties and good physical flexibility has potential to be used in the treatment of wastewater containing heavy metal as it could result in good saving in term of operational cost.

Impact of membrane lipid composition on the structure and stability of the transmembrane domain of amyloid precursor protein

PubMed Central

Dominguez, Laura; Foster, Leigh; Straub, John E.; Thirumalai, D.

2016-01-01

Cleavage of the amyloid precursor protein (APP) by γ-secretase is a crucial first step in the evolution of Alzheimer’s disease. To discover the cleavage mechanism, it is urgent to predict the structures of APP monomers and dimers in varying membrane environments. We determined the structures of the C9923−55 monomer and homodimer as a function of membrane lipid composition using a multiscale simulation approach that blends atomistic and coarse-grained models. We demonstrate that the C9923−55 homodimer structures form a heterogeneous ensemble with multiple conformational states, each stabilized by characteristic interpeptide interactions. The relative probabilities of each conformational state are sensitive to the membrane environment, leading to substantial variation in homodimer peptide structure as a function of membrane lipid composition or the presence of an anionic lipid environment. In contrast, the helicity of the transmembrane domain of monomeric C991−55 is relatively insensitive to the membrane lipid composition, in agreement with experimental observations. The dimer structures of human EphA2 receptor depend on the lipid environment, which we show is linked to the location of the structural motifs in the dimer interface, thereby establishing that both sequence and membrane composition modulate the complete energy landscape of membrane-bound proteins. As a by-product of our work, we explain the discrepancy in structures predicted for C99 congener homodimers in membrane and micelle environments. Our study provides insight into the observed dependence of C99 protein cleavage by γ-secretase, critical to the formation of amyloid-β protein, on membrane thickness and lipid composition. PMID:27559086

Pervaporative stripping of acetone, butanol and ethanol to improve ABE fermentation.

PubMed

Jitesh, K; Pangarkar, V G; Niranjan, K

2000-01-01

Acetone-butanol-ethanol fermentation by anaerobic bacterium C. acetobutylicum is a potential source for feedstock chemicals. The problem of product induced inhibition makes this fermentation economically infeasible. Pervaporation is studied as an effective separation technique to remove the toxic inhibitory products. Various membranes like Styrene Butadiene Rubber (SBR), Ethylene Propylene Diene Rubber (EPDM), plain Poly Dimethyl Siloxane (PDMS) and silicalite filled PDMS were studied for the removal of acetone, butanol and ethanol, from binary aqueous mixtures and from a quaternary mixture. It was found that the overall performance of PDMS filled with 15% w/w of silicalite was the best for removal of butanol in binary mixture study. SBR performance was best for the quaternary mixture studied.

Polystyrene Sulfonate Threaded through a Metal-Organic Framework Membrane for Fast and Selective Lithium-Ion Separation.

PubMed

Guo, Yi; Ying, Yulong; Mao, Yiyin; Peng, Xinsheng; Chen, Banglin

2016-11-21

Extraction of lithium ions from salt-lake brines is very important to produce lithium compounds. Herein, we report a new approach to construct polystyrene sulfonate (PSS) threaded HKUST-1 metal-organic framework (MOF) membranes through an in situ confinement conversion process. The resulting membrane PSS@HKUST-1-6.7, with unique anchored three-dimensional sulfonate networks, shows a very high Li + conductivity of 5.53×10 -4  S cm -1 at 25 °C, 1.89×10 -3  S cm -1 at 70 °C, and Li + flux of 6.75 mol m -2  h -1 , which are five orders higher than that of the pristine HKUST-1 membrane. Attributed to the different size sieving effects and the affinity differences of the Li + , Na + , K + , and Mg 2+ ions to the sulfonate groups, the PSS@HKUST-1-6.7 membrane exhibits ideal selectivities of 78, 99, and 10296 for Li + /Na + , Li + /K + , Li + /Mg 2+ and real binary ion selectivities of 35, 67, and 1815, respectively, the highest ever reported among ionic conductors and Li + extraction membranes. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Special Issue on Powering the Future Force: New Power & Energy Technologies for the Warfighter (AMMTIAC Quarterly, Volume 4, Number 1 / WSTIAC Quarterly, Volume 9, Number 1)

DTIC Science & Technology

2009-04-27

an aromatic acidic polymer such as SPEEK or SPSf. Figure 5 shows four basic polymers in which benzimidazole (BIm), amino- benzimidazole (ABIm...Z., A. Manthiram, and M. D. Guiver, “Blend Membranes Based on Sulfonated Polyetheretherketone and Polysulfone Bearing Benzimidazole Side Groups for...Sulfonated Poly(ether ether ketone) and Polysulfone Bearing Benzimidazole Side Groups for Direct Methanol Fuel Cells,” Electrochemical and Solid State Letters

MURI: An Integrated Multi-Scale Approach for Understanding Ion Transport in Complex Heterogeneous Organic Materials

DTIC Science & Technology

2017-09-30

characterization of PS-b-PVBC block copolymer and corresponding blends A micrometer blade film applicator was used to cast consistent films of various...means the titration is under tested. cMeasured at 20 °C in 18 MW water. Teflon stripe was running as background. The films were suspended in...overnight in the dark. Cross-linking of the membranes was achieved by exposure to UV light (Fusion UV systems, Inc. belt speed at 122 3, 7 runs

MURI: An Integrated Multi-Scale Approach for Understanding Ion Transport in Complex Heterogeneous Organic Materials

DTIC Science & Technology

2018-01-12

characterization of PS-b-PVBC block copolymer and corresponding blends A micrometer blade film applicator was used to cast consistent films of various...means the titration is under tested. cMeasured at 20 °C in 18 MW water. Teflon stripe was running as background. The films were suspended in...overnight in the dark. Cross-linking of the membranes was achieved by exposure to UV light (Fusion UV systems, Inc. belt speed at 122 3, 7 runs

Electrospun AOPAN/RC blend nanofiber membrane for efficient removal of heavy metal ions from water.

PubMed

Feng, Quan; Wu, Dingsheng; Zhao, Yong; Wei, Anfang; Wei, Qufu; Fong, Hao

2018-02-15

In this study, an innovative nano-material was prepared, which was ultilized to removal of heavy metal ions from wastewater. Polyacrylonitrile/cellulose acetate (PAN/CA) composite nanofibrous membranes were generated by the electronspinning technique first, and then amidoxime ployarcylonitrile/regenerate cellulose (AOPAN/RC) composite nanofibrous membranes were prepared by combining hydrolysis and amidoximation modification. The modification of composite nanofibers (AOPAN/RC) were consequently used in heavy metal ions adsorption. The characterizations of various different nanofibers were analyzed using scanning electron microscopy, Fourier transform infrared spectroscopy, surface area and pore size distribution analyzer and energy dispersive X-ray spectroscopy. Meantime, the adsorption equilibrium studies were studied. In addition, the saturation adsorption amount of nanofibrous membranes (at 25°C) for Fe(III), Cu(II) and Cd(II) of 7.47, 4.26 and 1.13mmolg -1 , respectively. The effects of pH value of solution, adsorption time and ions concentration on adsorption capacity were also investigated. Furthermore, the composite nanofibrous membranes after five times consecutive adsorption and desorption tests, the desorption rate of the Fe(III), Cu(II) and Cd(II) mental ions maintained more than 80% of their first desorption rate, AOPAN/RC composite nanofibrous reflected excellent resuability. Copyright © 2017 Elsevier B.V. All rights reserved.

Impact of swelling characteristics on the permselective ...

EPA Pesticide Factsheets

The removal of water from organic solvents and biofuels, including lower alcohols (i.e., methanol, ethanol, propanol, and butanol), is necessary for the production, blending, and reuse of those organic compounds. Water forms an azeotrope with many hydrophilic solvents, complicating the separation of water/solvent mixtures. The use of water-selective membranes in a pervaporation or vapor permeation process enables the removal of water from the solvents, even when an azeotrope is present. Common hydrophilic polymer membranes often swell in water, resulting in permeabilities and selectivities that are dependent on the water content of the feed mixture. Recent work has shown the benefit of overcoating a hydrophilic water-permselective membrane with a non-swelling perfluoropolymer film [1,2]. The perfluoropolymer layer reduces the activity of water the hydrophilic polymer layer experiences, thereby reducing swelling in that layer and increasing the water selectivity of the multi-layer membrane relative to the selectivity of the base hydrophilic polymer, usually at the expense of permeability. In this work, the effect of overcoating the hydrophilic layer with polymer films of various swelling characteristics was modelled. Top layers that swell in the solvent offer some advantages, particularly with regard to the water permeance of the multi-layer composite. 1. Huang, Y.; Baker, R. W.; Wijmans, J. G. Perfluoro-coated hydrophilic membranes with improved selectivity. In

Selectivity of Direct Methanol Fuel Cell Membranes.

PubMed

Aricò, Antonino S; Sebastian, David; Schuster, Michael; Bauer, Bernd; D'Urso, Claudia; Lufrano, Francesco; Baglio, Vincenzo

2015-11-24

Sulfonic acid-functionalized polymer electrolyte membranes alternative to Nafion(®) were developed. These were hydrocarbon systems, such as blend sulfonated polyetheretherketone (s-PEEK), new generation perfluorosulfonic acid (PFSA) systems, and composite zirconium phosphate-PFSA polymers. The membranes varied in terms of composition, equivalent weight, thickness, and filler and were investigated with regard to their methanol permeation characteristics and proton conductivity for application in direct methanol fuel cells. The behavior of the membrane electrode assemblies (MEA) was investigated in fuel cell with the aim to individuate a correlation between membrane characteristics and their performance in a direct methanol fuel cell (DMFC). The power density of the DMFC at 60 °C increased according to a square root-like function of the membrane selectivity. This was defined as the reciprocal of the product between area specific resistance and crossover. The power density achieved at 60 °C for the most promising s-PEEK-based membrane-electrode assembly (MEA) was higher than the benchmark Nafion(®) 115-based MEA (77 mW·cm(-2) vs. 64 mW·cm(-2)). This result was due to a lower methanol crossover (47 mA·cm(-2) equivalent current density for s-PEEK vs. 120 mA·cm(-2) for Nafion(®) 115 at 60 °C as recorded at OCV with 2 M methanol) and a suitable area specific resistance (0.15 Ohm cm² for s-PEEK vs. 0.22 Ohm cm² for Nafion(®) 115).

Selectivity of Direct Methanol Fuel Cell Membranes

PubMed Central

Aricò, Antonino S.; Sebastian, David; Schuster, Michael; Bauer, Bernd; D’Urso, Claudia; Lufrano, Francesco; Baglio, Vincenzo

2015-01-01

Sulfonic acid-functionalized polymer electrolyte membranes alternative to Nafion® were developed. These were hydrocarbon systems, such as blend sulfonated polyetheretherketone (s-PEEK), new generation perfluorosulfonic acid (PFSA) systems, and composite zirconium phosphate–PFSA polymers. The membranes varied in terms of composition, equivalent weight, thickness, and filler and were investigated with regard to their methanol permeation characteristics and proton conductivity for application in direct methanol fuel cells. The behavior of the membrane electrode assemblies (MEA) was investigated in fuel cell with the aim to individuate a correlation between membrane characteristics and their performance in a direct methanol fuel cell (DMFC). The power density of the DMFC at 60 °C increased according to a square root-like function of the membrane selectivity. This was defined as the reciprocal of the product between area specific resistance and crossover. The power density achieved at 60 °C for the most promising s-PEEK-based membrane-electrode assembly (MEA) was higher than the benchmark Nafion® 115-based MEA (77 mW·cm−2 vs. 64 mW·cm−2). This result was due to a lower methanol crossover (47 mA·cm−2 equivalent current density for s-PEEK vs. 120 mA·cm−2 for Nafion® 115 at 60 °C as recorded at OCV with 2 M methanol) and a suitable area specific resistance (0.15 Ohm cm2 for s-PEEK vs. 0.22 Ohm cm2 for Nafion® 115). PMID:26610582

Electroactive polymer based porous membranes for energy storage applications

NASA Astrophysics Data System (ADS)

Costa, Carlos Miguel da Silva

In the field of mobile applications the efficient storage of energy is one of the most critical issues. Lithium ion batteries are lighter, cheaper, show higher energy density (210Wh kg-1), no memory effect, longer service-life and higher number of charge/discharge cycles than other battery solutions. The separator membrane is placed between the anode and cathode and serves as the medium for the transfer of charge, being a critical components for the performance of the batteries. Polymers such as PVDF and its copolymers poly(vinylidene fluoride-co-trifluoroethylene), P(VDF-TrFE), poly(vinylidene fluoride-co-hexafluoropropylene), P(VDF-HFP), and poly(vinylidene fluoride-co-chlorotrifluoroethylene), P(VDF-CTFE) are increasingly investigated for their use as battery separators due to their high polarity, excellent thermal and mechanical properties, controllable porosity and wettability by organic solvents, being also chemically inert and stable in cathodic environment. Despite previous works in some of the PVDF co-polymers, there is no systematic investigations on poly(vinylidene fluoride-trifluoroethylene), P(VDF-TrFE), despite its large potential for this specific application. The objective of this work is thus establish the suitability of P(VDF-TrFE) for battery separators and to control of its structure, stability and ionic conductivity in order to increase performance of the material as battery separators. It is shown that solvent evaporation at room temperature allows the preparation of membranes with degrees of porosity from 70% to 80% leading to electrolyte solution uptakes from 250% up to 600%. The preparation of composites of P(VDF-TrFE) with lithium salts allows ionic conductivity values of the electrolytes of 2.3x10. -6 S/cm at 120 °C. These composites show good overall electrochemicalstability. A novel type of polymer blend based on poly(vinylidene fluoride-trifluoroethylene)/poly(ethylene oxide), P(VDF-TrFE)/PEO, was prepared and it was found that the microstructure, hydrophilicity and electrolyte uptake strongly depend on PEO content within the blend. For this blend, the best value of ionic conductivity at room temperature was 0.25 mS cm-1 for the 60/40 membrane. It was also verified that the ionic conductivity of the membrane is depend on the anion size of the salts present in the electrolyte solution, affecting also the electrolyte uptake value. Batteries fabricated with the separators developed in this work within Li/LiFePO4 and Li/Sn-C cells revealed very good cycling performance even at high current rates and 100% of depth of discharge (DOD), approaching the results achieved in liquid electrolytes. Good rate capability was observed in Li/LiFePO4 cathode cells, being able to deliver at 2C more that 90% of the capacity discharged at 0.1C. These results, in conjunction with the approximately 100% coulombic efficiency, indicate very good electrolyte/electrode compatibility. Thus, the developed materials showed suitable thermal, mechanical and electrochemical characteristics as well as high performance in battery applications, indicating the possibility of fabricating lithium-ion batteries with the battery separators developed in this work.

A Photometric Variability Survey of Field K and M Dwarf Stars with HATNet

NASA Astrophysics Data System (ADS)

Hartman, J. D.; Bakos, G. Á.; Noyes, R. W.; Sipőcz, B.; Kovács, G.; Mazeh, T.; Shporer, A.; Pál, A.

2011-05-01

Using light curves from the HATNet survey for transiting extrasolar planets we investigate the optical broadband photometric variability of a sample of 27, 560 field K and M dwarfs selected by color and proper motion (V - K >~ 3.0, μ > 30 mas yr-1, plus additional cuts in J - H versus H - KS and on the reduced proper motion). We search the light curves for periodic variations and for large-amplitude, long-duration flare events. A total of 2120 stars exhibit potential variability, including 95 stars with eclipses and 60 stars with flares. Based on a visual inspection of these light curves and an automated blending classification, we select 1568 stars, including 78 eclipsing binaries (EBs), as secure variable star detections that are not obvious blends. We estimate that a further ~26% of these stars may be blends with fainter variables, though most of these blends are likely to be among the hotter stars in our sample. We find that only 38 of the 1568 stars, including five of the EBs, have previously been identified as variables or are blended with previously identified variables. One of the newly identified EBs is 1RXS J154727.5+450803, a known P = 3.55 day, late M-dwarf SB2 system, for which we derive preliminary estimates for the component masses and radii of M 1 = M 2 = 0.258 ± 0.008 M sun and R 1 = R 2 = 0.289 ± 0.007 R sun. The radii of the component stars are larger than theoretical expectations if the system is older than ~200 Myr. The majority of the variables are heavily spotted BY Dra-type stars for which we determine rotation periods. Using this sample, we investigate the relations between period, color, age, and activity measures, including optical flaring, for K and M dwarfs, finding that many of the well-established relations for F, G, and K dwarfs continue into the M dwarf regime. We find that the fraction of stars that is variable with peak-to-peak amplitudes greater than 0.01 mag increases exponentially with the V - KS color such that approximately half of field dwarfs in the solar neighborhood with M <~ 0.2 M sun are variable at this level. Our data hint at a change in the rotation-activity-age connection for stars with M <~ 0.25 M sun.

Directed Self-Organization of Polymer-Grafted Nanoparticles in Polymer Thin Films

NASA Astrophysics Data System (ADS)

Zhang, Ren

The controlled organization of nanoparticle (NP) constituents into superstructures of well-defined shape, composition and connectivity represents a continuing challenge in the development of novel hybrid materials for many technological applications. Surface modification of NPs with grafted polymer ligands has emerged as a versatile means to control the interaction and organization of particle constituents in polymer-matrix composite materials. In this study, by incorporating polymer-grafted nanoparticles (PGNPs) into polymeric thin films, we aim to understand and control the spatial organization of PGNPs through the interactions between polymer brush layer and matrix chains. As model systems, we investigate thermodynamic behaviors of polystyrene-tethered gold nanoparticles (denoted as AuPS) dispersed in polymer thin film matrices with identical and different chemical compositions (PS and PMMA, respectively), and evaluate the influence of external perturbation fields on directed organization of nanofillers. With the presence of unfavorable enthalpic interactions between grafted and free polymer chains (i.e. AuPS/ PMMA blend thin films), phase-separated structures are generated upon thermal annealing, characterized with morphologies ranging from discrete droplets to spinodal structures, which is consistent with composition-dependent classic binary polymer blends phase separation. The phase separation kinetics of AuPS/ PMMA blends exhibit distinct features compared to the parent PS/ PMMA homopolymer blends. We further illustrate phase-separated AuPS-rich domains can be directed into unidirectionally aligned anisotropic structures through soft-shear dynamic zone annealing (DZA-SS) process with tunable domain aspect ratios. To exert exquisite control over the shape, size and location of phase-separated PGNP domains, topographically patterned elastomer confinement is introduced to PGNP/ polymer blend thin films during thermal annealing. When the phase-separated lengthscale coincides with confined pattern dimension, long-range ordered submicron-sized AuPS domains are generated in PMMA matrices with dense and well-dispersed nanoparticle distribution. Furthermore, preferential segregation of AuPS nanoparticles at patterned mesa regions can be induced in PS matrices where enthalpic interactions are absent. This selective segregation is achieved due to the local perturbation of grafted chains when confined in a restricted space. The efficiency of this particle segregation process within patterned mesa-trench films can be tuned by changing the relative entropic confinement effects on grafted and matrix chains. This physical pattern directed PGNP organization strategy is applicable to versatile pattern geometries and nanoparticle compositions.

Sensitivity analysis for linear structural equation models, longitudinal mediation with latent growth models and blended learning in biostatistics education

NASA Astrophysics Data System (ADS)

Sullivan, Adam John

In chapter 1, we consider the biases that may arise when an unmeasured confounder is omitted from a structural equation model (SEM) and sensitivity analysis techniques to correct for such biases. We give an analysis of which effects in an SEM are and are not biased by an unmeasured confounder. It is shown that a single unmeasured confounder will bias not just one but numerous effects in an SEM. We present sensitivity analysis techniques to correct for biases in total, direct, and indirect effects when using SEM analyses, and illustrate these techniques with a study of aging and cognitive function. In chapter 2, we consider longitudinal mediation with latent growth curves. We define the direct and indirect effects using counterfactuals and consider the assumptions needed for identifiability of those effects. We develop models with a binary treatment/exposure followed by a model where treatment/exposure changes with time allowing for treatment/exposure-mediator interaction. We thus formalize mediation analysis with latent growth curve models using counterfactuals, makes clear the assumptions and extends these methods to allow for exposure mediator interactions. We present and illustrate the techniques with a study on Multiple Sclerosis(MS) and depression. In chapter 3, we report on a pilot study in blended learning that took place during the Fall 2013 and Summer 2014 semesters here at Harvard. We blended the traditional BIO 200: Principles of Biostatistics and created ID 200: Principles of Biostatistics and epidemiology. We used materials from the edX course PH207x: Health in Numbers: Quantitative Methods in Clinical & Public Health Research and used. These materials were used as a video textbook in which students would watch a given number of these videos prior to class. Using surveys as well as exam data we informally assess these blended classes from the student's perspective as well as a comparison of these students with students in another course, BIO 201: Introduction to Statistical Methods in Fall 2013 as well as students from BIO 200 in Fall semesters of 1992 and 1993. We then suggest improvements upon our original course designs and follow up with an informal look at how these implemented changes affected the second offering of the newly blended ID 200 in Summer 2014.

Interaction pathways between soft lipid nanodiscs and plasma membranes: A molecular modeling study.

PubMed

Li, Shixin; Luo, Zhen; Xu, Yan; Ren, Hao; Deng, Li; Zhang, Xianren; Huang, Fang; Yue, Tongtao

2017-10-01

Lipid nanodisc, a model membrane platform originally synthesized for study of membrane proteins, has recently been used as the carrier to deliver amphiphilic drugs into target tumor cells. However, the central question of how cells interact with such emerging nanomaterials remains unclear and deserves our research for both improving the delivery efficiency and reducing the side effect. In this work, a binary lipid nanodisc is designed as the minimum model to investigate its interactions with plasma membranes by using the dissipative particle dynamics method. Three typical interaction pathways, including the membrane attachment with lipid domain exchange of nanodiscs, the partial membrane wrapping with nanodisc vesiculation, and the receptor-mediated endocytosis, are discovered. For the first pathway, the boundary normal lipids acting as ligands diffuse along the nanodisc rim to gather at the membrane interface, repelling the central bola lipids to reach a stable membrane attachment. If bola lipids are positioned at the periphery and act as ligands, they diffuse to form a large aggregate being wrapped by the membrane, leaving the normal lipids exposed on the membrane exterior by assembling into a vesicle. Finally, by setting both central normal lipids and boundary bola lipids as ligands, the receptor-mediated endocytosis occurs via both deformation and self-rotation of the nanodiscs. All above pathways for soft lipid nanodiscs are quite different from those for rigid nanoparticles, which may provide useful guidelines for design of soft lipid nanodiscs in widespread biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Investigation of Free-Standing Plasmonic Mesoporous Ag/CMK-8-Nafion Composite Membrane for the Removal of Organic Pollutants with 254-nm UV Irradiation

NASA Astrophysics Data System (ADS)

Tseng, Chuan Ming; Chen, Hsin Liang; Lai, Sz Nian; Chen, Ming Shiung; Peng, Chien Jung; Li, Chia Jui; Hung, Wei Hsuan

2017-05-01

"Carbon-based material" has demonstrated a great potential on water purification due to its strong physical adsorption to organic pollutants in the water. Three-dimensional cubic ordered mesoporous carbon (CMK-8), one of the well-known ordered mesoporous carbons, was prepared by using nanocasting method with mesoporous silica (KIT-6) as the template. In this study, CMK-8 blended with Nafion polymer to form a free-standing mesoporous CMK-8-Nafion composite membrane. The synthesis of high crystallinity CMK-8 was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). More than 80% methyl orange (MO) removal efficiency was observed under 254-nm UV irradiation after 120 min. Ninety-two percent recycling performance was remained after four recycling tests, which indicated a reliable servicing lifetime for the water purification. Furthermore, an additional layer of plasmonic silver nanoparticles (Ag NPs) was integrated into this CMK-8-Nafion membrane for higher pollutant removal efficiency, attributing from the generation of plasmon-resonance hot electrons from Ag NPs. A 4-in. CMK-8-Nafion composite membrane was also fabricated for the demonstration of potential large-scale utilization.

Effects of TiO2 and ZrO2 nanofillers in LiBOB based PVdF/PVC composite polymer electrolytes (CPE)

NASA Astrophysics Data System (ADS)

Aravindan, V.; Vickraman, P.

2007-11-01

A novel type of lithium bis(oxalato)borate (LiBOB) synthesized by the solid-state reaction method has been presented. LiBOB composite polymer electrolytes (CPE) prepared with dispersions of TIO2/ZrO2with various concentrations into the host blend matrices of poly(vinylidenefluoride) (PVdF)-poly(vinylchloride) (PVC) are investigated by scanning electron microscopy, x-ray diffraction (XRD) and ac impedance measurements. The plasticizing agent selected for the present study is a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) for the phase separated morphology of the studied polymers. The impedance studies on CPE membranes identify that membranes, with 2.5 wt% of fillers, have enhanced conductivities of 5.43 × 10-4 S cm-1 and 4.38 × 10-4 S cm-1, respectively, for TiO2 and ZrO2 at ambient temperature. The XRD investigations confirm that the membranes with filler levels exceeding the limit of 2.5 wt% show a gradual increase in the degree of crystallinity, rendering them less conducting. The activation energy calculations also highlight variations in conductivities of all the membranes.

Effect of concentration boundary layers on passive solute flows in a system of two polymeric membranes positioned in vertical planes.

PubMed

Slezak, Andrzej; Jasik-Slezak, Jolanta; Dworecki, Kazimierz

2003-01-01

The results of studies of influence of concentration boundary layers on passive diffusive transport in a double-membrane osmo-diffusive cell, containing a series of two (Ml and M(r)) vertically positioned, flat, microporous and symmetric polymer membranes (Nephrophane and Cellulose IMP-1) are presented in this paper. The membranes separated three compartments (l, m, r) containing binary, heterogeneous and non-ionic solutions (aqueous solutions of glucose or ethanol) or ternary non-electrolyte solutions (glucose solutions in 0.75 mol.l-1 solution of ethanol or ethanol solutions in 0.1 mol.l-1 aqueous solution of glucose). Solution concentrations fulfilled the condition C(k)l > C(k)m > C(k)r. The intermembrane compartment (m) was an infinitesimal solution layer. The volume of the m compartment and the volumes of the external (l and r) compartments fulfilled the condition Vl = Vr approximately 170 Vm. The tests were performed for configurations A and B of a double-membrane osmo-diffusive cell. In configuration A, the solution was located behind the M(r) membrane, and water was placed behind the Ml membrane, while in configuration B this sequence was reversed. The results obtained during experiment were interpreted in the categories of convective instability, which increased the value of diffusive permeability coefficient of the system: concentration boundary layer/membrane/concentration boundary layer.

A CAUTIONARY TALE: MARVELS BROWN DWARF CANDIDATE REVEALS ITSELF TO BE A VERY LONG PERIOD, HIGHLY ECCENTRIC SPECTROSCOPIC STELLAR BINARY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mack, Claude E. III; Stassun, Keivan G.; De Lee, Nathan

2013-05-15

We report the discovery of a highly eccentric, double-lined spectroscopic binary star system (TYC 3010-1494-1), comprising two solar-type stars that we had initially identified as a single star with a brown dwarf companion. At the moderate resolving power of the MARVELS spectrograph and the spectrographs used for subsequent radial-velocity (RV) measurements (R {approx}< 30, 000), this particular stellar binary mimics a single-lined binary with an RV signal that would be induced by a brown dwarf companion (Msin i {approx} 50 M{sub Jup}) to a solar-type primary. At least three properties of this system allow it to masquerade as a singlemore » star with a very-low-mass companion: its large eccentricity (e {approx} 0.8), its relatively long period (P {approx} 238 days), and the approximately perpendicular orientation of the semi-major axis with respect to the line of sight ({omega} {approx} 189 Degree-Sign ). As a result of these properties, for {approx}95% of the orbit the two sets of stellar spectral lines are completely blended, and the RV measurements based on centroiding on the apparently single-lined spectrum is very well fit by an orbit solution indicative of a brown dwarf companion on a more circular orbit (e {approx} 0.3). Only during the {approx}5% of the orbit near periastron passage does the true, double-lined nature and large RV amplitude of {approx}15 km s{sup -1} reveal itself. The discovery of this binary system is an important lesson for RV surveys searching for substellar companions; at a given resolution and observing cadence, a survey will be susceptible to these kinds of astrophysical false positives for a range of orbital parameters. Finally, for surveys like MARVELS that lack the resolution for a useful line bisector analysis, it is imperative to monitor the peak of the cross-correlation function for suspicious changes in width or shape, so that such false positives can be flagged during the candidate vetting process.« less

Removal of chromium (VI) ions from aqueous solutions using amine-impregnated TiO2 nanoparticles modified cellulose acetate membranes.

PubMed

Gebru, Kibrom Alebel; Das, Chandan

2018-01-01

In this work, TiO 2 nanoparticles (NPs) were modified using tetraethylenepentamine (TEPA), ethylenediamine (EDA), and hexamethylenetetramine (HMTA) amines using impregnation process. The prepared amine modified TiO 2 samples were explored as an additive to fabricate ultrafiltration membranes with enhanced capacity towards the removal of chromium ions from aqueous solution. Modified membranes were prepared from cellulose acetate (CA) polymer blended with polyethylene glycol (PEG) additive, and amine modified TiO 2 by using phase inversion technique. Fourier transform infrared spectroscopy (FTIR), zeta potential (ζ), thermo gravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), water contact angle (WCA), and atomic absorption spectrophotometer (AAS) studies were done to characterize the membranes in terms of chemical structure, electric charge, thermal stability, morphology, hydrophilicity, and removal performance. The pure water permeability and Cr (VI) ion removal efficiency of the unmodified (i.e. CA/U-Ti) and the amine modified (CA/Ti-HMTA, CA/Ti-EDA, and CA/Ti-TEPA) membranes were dependent on pH and metal ion concentration. Incorporation of amine modified TiO 2 composite to the CA polymer was found to improve the fouling and removal characteristics of the membranes during the chromium ultrafiltration process. The maximum removal efficiency result of Cr (VI) ions at pH of 3.5 using CA/Ti-TEPA membrane was 99.8%. The washing/regeneration cycle results in this study described as an essential part for prospect industrial applications of the prepared membranes. The maximum Cr (VI) removal results by using CA/Ti-TEPA membrane for four washing/regeneration cycles are 99.6%, 99.5%, 98.6% and, 96.6%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of native silk fibroin powder on the physical properties and biocompatibility of biomedical polyurethane membrane.

PubMed

Zhuang, Yan; Zhang, Qian; Feng, Jinqi; Wang, Na; Xu, Weilin; Yang, Hongjun

2017-04-01

Naturally derived fibers such as silk fibroin can potentially enhance the biocompatibility of currently used biomaterials. This study investigated the physical properties of native silk fibroin powder and its effect on the biocompatibility of biomedical polyurethane. Native silk fibroin powder with an average diameter of 3 µm was prepared on a purpose-built machine. A simple method of phase inversion was used to produce biomedical polyurethane/native silk fibroin powder hybrid membranes at different blend ratios by immersing a biomedical polyurethane/native silk fibroin powder solution in deionized water at room temperature. The physical properties of the membranes including morphology, hydrophilicity, roughness, porosity, and compressive modulus were characterized, and in vitro biocompatibility was evaluated by seeding the human umbilical vein endothelial cells on the top surface. Native silk fibroin powder had a concentration-dependent effect on the number and morphology of human umbilical vein endothelial cells growing on the membranes; cell number increased as native silk fibroin powder content in the biomedical polyurethane/native silk fibroin powder hybrid membrane was increased from 0% to 50%, and cell morphology changed from spindle-shaped to cobblestone-like as the native silk fibroin powder content was increased from 0% to 70%. The latter change was related to the physical characteristics of the membrane, including hydrophilicity, roughness, and mechanical properties. The in vivo biocompatibility of the native silk fibroin powder-modified biomedical polyurethane membrane was evaluated in a rat model; the histological analysis revealed no systemic toxicity. These results indicate that the biomedical polyurethane/native silk fibroin powder hybrid membrane has superior in vitro and in vivo biocompatibility relative to 100% biomedical polyurethane membranes and thus has potential applications in the fabrication of small-diameter vascular grafts and in tissue engineering.

The impact of charge on the cooling performance of an air-to-air heat pump for R-22 and three binary blends of R-32 and R-134a

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robinson, J.H.; O`Neal, D.L.

1994-12-31

An experimental study was conducted in which the performance of three blends of R-134a and R-32 was compared to that of R-22. The effect of refrigerant charge on the performance of these refrigerants in an air-to-air heat pump operating in the cooling mode was quantified The mixtures consisted of 40%/60%, 30%/70%, and 20%/80% ratios (by mass) of R-32 and R-134a. Charge levels of 5.00, 5.45, 5.90, and 6.00 kg (11, 12, 13, and 14 lb) were tested. At each charge level, outdoor room conditions of 27.8 C, 35.0 C, and 40.6 C (82 F, 95 F, and 105 F) weremore » tested The expansion device for all tests was a 1.96 mm (0.077 in.) diameter orifice. Three variables were used to quantify refrigerant performance-total capacity, total electrical power consumption, and coefficient of performance (COP). The performance of the heat pump with any of the three mixtures was not as good as with R-22. The capacities were between 7% and 17% less than with R-22. The best COPs with the mixtures were within 3% of that with R-22 in some cases, but the corresponding capacities at these COPs were approximately 12% lower than that in the R-22 base case. The best results for a mixture were with the 40%/60% blend. The capacity was 7.3% less than the base case and the COP was 8.5% lower.« less

To evaluate the effect of various magnesium stearate polymorphs using powder rheology and thermal analysis.

PubMed

Okoye, Patrick; Wu, Stephen H; Dave, Rutesh H

2012-12-01

The effects of magnesium stearate (MgSt) polymorphs-anhydrate (MgSt-A), monohydrate (MgSt-M), and dihydrate (MgSt-D)-on rheological properties of powders were evaluated using techniques such as atomic analysis and powder rheometry. Additional evaluation was conducted using thermal analysis, micromeritics, and tableting forces. In this study, binary ratios of neat MgSt polymorphs were employed as lubricants in powder blends containing acetaminophen (APAP), microcrystalline cellulose (MCC), and lactose monohydrate (LAC-M). Powder rheometry was studied using permeability, basic flow energy (BFE), density, and porosity analysis. Thermal conductivity and differential scanning calorimetric analysis of MgSt polymorphs were employed to elucidate MgSt effect on powder blends. The impact of MgSt polymorphs on compaction characteristics were analyzed via tablet compression forces. Finally, the distribution of atomized magnesium (Mg) ions as a function of intensity was evaluated using laser-induced breakdown spectroscopy (LIBS) on tablets. The results from LIBS analysis indicated the dependency of the MgSt polymorphic forms on the atomized Mg ion intensity, with higher Mg ion intensity suggesting higher lubricity index (i.e. greater propensity to over-lubricate). The results from lubricity index suggested the tendency of blends to over-lubricate based on the MgSt polymorphic forms. Finally, tableting forces suggested that MgSt-D and MgSt-A offered processing benefits such as lower ejection and compression forces, and that MgSt-M showed the most stable compression force in single or combined polymorphic ratios. These results suggested that the initial moisture content, crystal arrangement, intra- and inter-molecular packing of the polymorphs defined their effects on the rheology of lubricated powders.

How learning analytics can early predict under-achieving students in a blended medical education course.

PubMed

Saqr, Mohammed; Fors, Uno; Tedre, Matti

2017-07-01

Learning analytics (LA) is an emerging discipline that aims at analyzing students' online data in order to improve the learning process and optimize learning environments. It has yet un-explored potential in the field of medical education, which can be particularly helpful in the early prediction and identification of under-achieving students. The aim of this study was to identify quantitative markers collected from students' online activities that may correlate with students' final performance and to investigate the possibility of predicting the potential risk of a student failing or dropping out of a course. This study included 133 students enrolled in a blended medical course where they were free to use the learning management system at their will. We extracted their online activity data using database queries and Moodle plugins. Data included logins, views, forums, time, formative assessment, and communications at different points of time. Five engagement indicators were also calculated which would reflect self-regulation and engagement. Students who scored below 5% over the passing mark were considered to be potentially at risk of under-achieving. At the end of the course, we were able to predict the final grade with 63.5% accuracy, and identify 53.9% of at-risk students. Using a binary logistic model improved prediction to 80.8%. Using data recorded until the mid-course, prediction accuracy was 42.3%. The most important predictors were factors reflecting engagement of the students and the consistency of using the online resources. The analysis of students' online activities in a blended medical education course by means of LA techniques can help early predict underachieving students, and can be used as an early warning sign for timely intervention.

Confirmation of an exoplanet using the transit color signature: Kepler-418b, a blended giant planet in a multiplanet system

NASA Astrophysics Data System (ADS)

Tingley, B.; Parviainen, H.; Gandolfi, D.; Deeg, H. J.; Palle, E.; Montañés Rodriguez, P.; Murgas, F.; Alonso, R.; Bruntt, H.; Fridlund, M.

2014-07-01

Aims: We announce confirmation of Kepler-418b, one of two proposed planets in this system. This is the first confirmation of an exoplanet based primarily on the transit color signature technique. Methods: We used the Kepler public data archive combined with multicolor photometry from the Gran Telescopio de Canarias and radial velocity follow-up using FIES at the Nordic Optical Telescope for confirmation. Results: We report a confident detection of a transit color signature that can only be explained by a compact occulting body, entirely ruling out a contaminating eclipsing binary, a hierarchical triple, or a grazing eclipsing binary. Those findings are corroborated by our radial velocity measurements, which put an upper limit of ~1 MJup on the mass of Kepler-418b. We also report that the host star is significantly blended, confirming the ~10% light contamination suspected from the crowding metric in the Kepler light curve measured by the Kepler team. We report detection of an unresolved light source that contributes an additional ~30% to the target star, which would not have been detected without multicolor photometric analysis. The resulting planet-star radius ratio is 0.110 ± 0.0025, more than 25% more than the 0.087 measured by Kepler leading to a radius of 1.20 ± 0.16 RJup instead of the 0.94 RJup measured by the Kepler team. Conclusions: This is the first confirmation of an exoplanet candidate based primarily on the transit color signature, demonstrating that this technique is viable from ground for giant planets. It is particularly useful for planets with long periods such as Kepler-418b, which tend to have long transit durations. While this technique is limited to candidates with deep transits from the ground, it may be possible to confirm earth-like exoplanet candidates with a few hours of observing time with an instrument like the James Webb Space Telescope. Additionally, multicolor photometric analysis of transits can reveal unknown stellar neighbors and binary companions that do not affect the classification of the transiting object but can have a very significant effect on the perceived planetary radius. GTC g' and z' photometry and NOT-FIES spectroscopy are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A14

Formation of supported lipid bilayers containing phase-segregated domains and their interaction with gold nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melby, Eric S.; Mensch, Arielle C.; Lohse, Samuel E.

2016-01-01

The cell membrane represents an important biological interface that nanoparticles may encounter after being released into the environment. Interaction of nanoparticles with cellular membranes may alter membrane structure and function, lead to their uptake into cells, and elicit adverse biological responses. Supported lipid bilayers have proven to be valuable ex vivo models for biological membranes, allowing investigation of their mechanisms of interaction with nanoparticles with a degree of control impossible in living cells. To date, the majority of research on nanoparticle interaction with supported lipid bilayers has employed membranes composed of single or binary mixtures of phospholipids. Cellular membranes containmore » a wide variety of lipids and exhibit lateral organization. Ordered membrane domains enriched in specific membrane components are referred to as lipid rafts and have not been explored with respect to their interaction with nanoparticles. Here we develop model lipid raft-containing membranes amenable to investigation by a variety of surface-sensitive analytical techniques and demonstrate that lipid rafts influence the extent of nanoparticle attachment to model membranes. We determined conditions that allow reliable formation of bilayers containing rafts enriched in sphingomyelin and cholesterol and confirmed their morphology by structured illumination and atomic force microscopies. We demonstrate that lipid rafts increase attachment of cationic gold nanoparticles to model membranes under near physiological ionic strength conditions (0.1 M NaCl) at pH 7.4. We anticipate that these results will serve as the foundation for and motivate further study of nanoparticle interaction with compositionally varied lipid rafts.« less

Ordered Materials via Additive Driven Assembly and Reaction using Surfactant-Based Templates

NASA Astrophysics Data System (ADS)

Beaulieu, Michael R.; Daga, Vikram K.; Lesser, Alan J.; Watkins, James J.

2011-03-01

We recently reported (1) the ordering behavior of Pluronic surfactant melts through the addition of aromatic additives with hydrogen bond donating groups, which exhibit selective interactions with the polyethylene oxide (PEO) block. The ordered blends had domain sizes ranging from 12 to 16 nm at additive loadings up to 80%.The goal of this work is to utilize condensation chemistries based on the functionality of similar additives, to yield ordered composite materials that could be used for applications involving membranes or dielectric materials. The structure of the blends and composites are determined by small angle x-ray scattering, which indicates that the ordered structure is preserved following reaction of the additives. Differential scanning calorimetry indicates that an increase in additive loading causes a decrease in the melting temperature and enthalpy of melting of the PEO, which demonstrates that the interaction between the PEO segments and the additive is strong. (1) Daga, V.K., Watkins, J. J. Macromolecules, ASAP.

Sustainable construction: composite use of tyres and ash in concrete.

PubMed

Snelson, D G; Kinuthia, J M; Davies, P A; Chang, S-R

2009-01-01

An investigation was carried out to establish the physical, mechanical and chemical characteristics of a non-standard (unprocessed) pulverised fuel ash (PFA) and waste tyres from a former landfill site at the Power Station Hill near Church Village, South Wales, United Kingdom. Investigations are on-going to establish the suitability of the fly ash and/or tyres in road construction (embankment and pavement) and also in concrete to be used in the construction of the proposed highway. This paper reports on concrete-based construction where concrete blends (using various levels of PFA as partial replacement for Portland cement (PC), and shredded waste tyres (chips 15-20mm) as aggregate replacement) were subjected to unconfined compressive strength tests to establish performance, hence, optimising mix designs. Strength development up to 180 days for the concrete made with PC-PFA blends as binders (PC-PFA concrete), with and without aggregate replacement with tyre chips, is reported. The binary PC-PFA concrete does not have good early strength but tends to improve at longer curing periods. The low early strength observed means that PC-PFA concrete cannot be used for structures, hence, only as low to medium strength applications such as blinding, low-strength foundations, crash barriers, noise reduction barriers, cycle paths, footpaths and material for pipe bedding.

Sustainable construction: Composite use of tyres and ash in concrete

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snelson, D.G.; Kinuthia, J.M.; Davies, P.A.

2009-01-15

An investigation was carried out to establish the physical, mechanical and chemical characteristics of a non-standard (unprocessed) pulverised fuel ash (PFA) and waste tyres from a former landfill site at the Power Station Hill near Church Village, South Wales, United Kingdom. Investigations are on-going to establish the suitability of the fly ash and/or tyres in road construction (embankment and pavement) and also in concrete to be used in the construction of the proposed highway. This paper reports on concrete-based construction where concrete blends (using various levels of PFA as partial replacement for Portland cement (PC), and shredded waste tyres (chipsmore » 15-20 mm) as aggregate replacement) were subjected to unconfined compressive strength tests to establish performance, hence, optimising mix designs. Strength development up to 180 days for the concrete made with PC-PFA blends as binders (PC-PFA concrete), with and without aggregate replacement with tyre chips, is reported. The binary PC-PFA concrete does not have good early strength but tends to improve at longer curing periods. The low early strength observed means that PC-PFA concrete cannot be used for structures, hence, only as low to medium strength applications such as blinding, low-strength foundations, crash barriers, noise reduction barriers, cycle paths, footpaths and material for pipe bedding.« less

Enhanced Bioaccessibility of Crocetin Sugar Esters from Saffron in Infusions Rich in Natural Phenolic Antioxidants.

PubMed

Ordoudi, Stella A; Kyriakoudi, Anastasia; Tsimidou, Maria Z

2015-09-25

The present study aims to examine whether and to what extent the bioaccessibility of the major saffron apocarotenoids, namely crocetin sugar esters (CRTSEs), is affected by the presence of strong water-soluble antioxidants, ingredients of the herbs found in commercial tea blends with saffron. An in vitro digestion model was applied to infusions from these products to investigate the possible changes. All of the studied infusions were rich in total phenols (9.9-22.5 mg caffeic acid equivalents/100 mg dry infusion) and presented strong DPPH radical scavenging activity regardless of the composition of the corresponding herbal blends. RP-HPLC-DAD and LC-MS analysis enabled the grouping of the infusions into hydroxycinnamic acid-rich and in flavan-3-ol-rich ones. CRTSEs in herbal tea infusions were found to be significantly more bioaccessible (66.3%-88.6%) than those in the reference saffron infusion (60.9%). The positive role of strong phenolic antioxidants (caffeic acid, rosmarinic acid) on the stability of CRTSEs was also evidenced in model binary mixtures. On the contrary, cinnamic acid, exerting no antioxidant activity, did not have such an effect. Our findings suggest that strong radical scavengers may protect the crocetin sugar esters from oxidation during digestion when present in excess.

Development of a Supported Emulsion Liquid Membrane System for Propionic Acid Separation in a Microgravity Environment

NASA Technical Reports Server (NTRS)

Li, Jin; Hu, Shih-Yao B.; Wiencek, John M.

2001-01-01

Perstractive fermentation is a good way to increase the productivity of bioreactors. Using Propionibacteria as the model system, the feasibility of using supported emulsion liquid membrane (SELM) for perstractive fermentation is assessed in this study. Five industrial solvents were considered as the solvent for preparing the SELM. The more polar a solvent is, the higher the partition coefficient. However, toxicity of a solvent also increases with its polarity. CO-1055 (industrial decanol/octanol blend) has the highest partition coefficient toward propionic acid among the solvents that has no molecular toxicity toward Propionibacteria. A preliminary extraction study was conducted using tetradecane as solvent in a hydrophobic hollow fiber contactor. The result confirmed that SELM eliminates the equilibrium limitation of conventional liquid-liquid extraction, and allows the use of a non-toxic solvent with low partition coefficient.

Pressure-assisted synthesis of HKUST-1 thin film on polymer hollow fiber at room temperature toward gas separation.

PubMed

Mao, Yiyin; Li, Junwei; Cao, Wei; Ying, Yulong; Sun, Luwei; Peng, Xinsheng

2014-03-26

The scalable fabrication of continuous and defect-free metal-organic framework (MOF) films on the surface of polymeric hollow fibers, departing from ceramic supported or dense composite membranes, is a huge challenge. The critical way is to reduce the growth temperature of MOFs in aqueous or ethanol solvents. In the present work, a pressure-assisted room temperature growth strategy was carried out to fabricate continuous and well-intergrown HKUST-1 films on a polymer hollow fiber by using solid copper hydroxide nanostrands as the copper source within 40 min. These HKUST-1 films/polyvinylidenefluoride (PVDF) hollow fiber composite membranes exhibit good separation performance for binary gases with selectivity 116% higher than Knudsen values via both inside-out and outside-in modes. This provides a new way to enable for scale-up preparation of HKUST-1/polymer hollow fiber membranes, due to its superior economic and ecological advantages.

Binary actin-ADP-ribosylating toxins and their use as molecular Trojan horses for drug delivery into eukaryotic cells.

PubMed

Barth, Holger; Stiles, Bradley G

2008-01-01

Binary bacterial toxins are unique AB-type toxins, composed of two non-linked proteins that act as a binding/translocation component and an enzyme component. All known actin-ADP-ribosylating toxins from clostridia possess this binary structure. This toxin family is comprised of the prototypical Clostridium botulinum C2 toxin, Clostridium perfringens iota toxin, Clostridium difficile CDT, and Clostridium spiroforme toxin. Once in the cytosol of host cells, these toxins transfer an ADP-ribose moiety from nicotinamide-adenosine-dinucleotide onto G-actin that then leads to depolymerization of actin filaments. In recent years much progress has been made towards understanding the cellular uptake mechanism of binary actin-ADP-ribosylating toxins, and in particular that of C2 toxin. Both components act in a precisely concerted manner to intoxicate eukaryotic cells. The binding/translocation (B-) component forms a complex with the enzyme (A-) component and mediates toxin binding to a cell-surface receptor. Following receptor-mediated endocytosis, the enzyme component escapes from acidic endosomes into the cytosol. Acidification of endosomes triggers pore formation by the binding/translocation component in endosomal membranes and the enzyme component subsequently translocates through the pore. This step requires a host cell chaperone, Hsp90. Due to their unique structure, binary toxins are naturally "tailor made" for transporting foreign proteins into the cytosol of host cells. Several highly specific and cell-permeable recombinant fusion proteins have been designed and successfully used in experimental cell research. This review will focus on the recent progress in studying binary actin ADP-ribosylating toxins as highly effective virulence factors and innovative tools for cell physiology as well as pharmacology.

The role of hydrodynamic stress on the phenotypic characteristics of single and binary biofilms of Pseudomonas fluorescens.

PubMed

Simões, M; Pereira, M O; Vieira, M J

2007-01-01

This study investigates the phenotype of turbulent (Re = 5,200) and laminar (Re = 2,000) flow-generated Pseudomonas fluorescens biofilms. Three P. fluorescens strains, the type strain ATCC 13525 and two strains isolated from an industrial processing plant, D3-348 and D3-350, were used throughout this study. The isolated strains were used to form single and binary biofilms. The biofilm physiology (metabolic activity, cellular density, mass, extracellular polymeric substances, structural characteristics and outer membrane proteins [OMP] expression) was compared. The results indicate that, for every situation, turbulent flow-generated biofilms were more active (p < 0.05), had more mass per cm(2) (p < 0.05), a higher cellular density (p < 0.05), distinct morphology, similar matrix proteins (p > 0.1) and identical (isolated strains -single and binary biofilms) and higher (type strain) matrix polysaccharides contents (p < 0.05) than laminar flow-generated biofilms. Flow-generated biofilms formed by the type strain revealed a considerably higher cellular density and amount of matrix polysaccharides than single and binary biofilms formed by the isolated strains (p < 0.05). Similar OMP expression was detected for the several single strains and for the binary situation, not dependent on the hydrodynamic conditions. Binary biofilms revealed an equal coexistence of the isolated strains with apparent neutral interactions. In summary, the biofilms formed by the type strain represent, apparently, the worst situation in a context of control. The results obtained clearly illustrate the importance of considering strain variation and hydrodynamics in biofilm development, and complement previous studies which have focused on physical aspects of structural and density differences.

ISM DUST GRAINS AND N-BAND SPECTRAL VARIABILITY IN THE SPATIALLY RESOLVED SUBARCSECOND BINARY UY Aur

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skemer, Andrew J.; Close, Laird M.; Hinz, Philip M.

2010-03-10

The 10 {mu}m silicate feature is an essential diagnostic of dust-grain growth and planet formation in young circumstellar disks. The Spitzer Space Telescope has revolutionized the study of this feature, but due to its small (85 cm) aperture, it cannot spatially resolve small/medium-separation binaries ({approx}<3''; {approx}< 420 AU) at the distances of the nearest star-forming regions ({approx}140 pc). Large, 6-10 m ground-based telescopes with mid-infrared instruments can resolve these systems. In this paper, we spatially resolve the 0.''88 binary, UY Aur, with MMTAO/BLINC-MIRAC4 mid-infrared spectroscopy. We then compare our spectra to Spitzer/IRS (unresolved) spectroscopy, and resolved images from IRTF/MIRAC2, Keck/OSCIR,more » and Gemini/Michelle, which were taken over the past decade. We find that UY Aur A has extremely pristine, interstellar medium (ISM)-like grains and that UY Aur B has an unusually shaped silicate feature, which is probably the result of blended emission and absorption from foreground extinction in its disk. We also find evidence for variability in both UY Aur A and UY Aur B by comparing synthetic photometry from our spectra with resolved imaging from previous epochs. The photometric variability of UY Aur A could be an indication that the silicate emission itself is variable, as was recently found in EX Lupi. Otherwise, the thermal continuum is variable, and either the ISM-like dust has never evolved, or it is being replenished, perhaps by UY Aur's circumbinary disk.« less

Nanofiltration properties of PTMSP in binary organic solvents mixtures

NASA Astrophysics Data System (ADS)

Yushkin, A. A.; Kossov, A. A.; Volkov, V. V.

2016-09-01

In this study, the stability and nanofiltration performance of poly[1-(trimethylsilyl)- 1-propyne] (PTMSP) in ethanol solutions of butylaldehyde, 1-decanal, 1-hexene, 1-decene was evaluated. It was found that PTMSP was insoluble in all aldehyde solutions, but it was soluble at olefin concentration of 80% or higher. Nanofiltration experiments demonstrate that binary mixtures of 1-decanal and ethanol viscosity are not the parameter affecting on membrane permeability and rejection of solute as well as swelling degree. In the case of decanol/ethanol solutions both solution viscosity and molar volume demonstrate the best fit of experimental data. It was shown that with the decrease of ethanol content in the feed, the rejection of anionic solute Remazol Brilliant Blue R (MW 626) increases from 94 up to 97%.

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

The objective of Task I is to prepare and evaluate catalysts and to develop efficient reactor systems for the selective conversion of hydrogen-lean synthesis gas to alcohol fuel extenders and octane enhancers. In Task 1, during this reporting period, we encountered and solved a problem in the analysis of the reaction products containing a small amount of heavy components. Subsequently, we continued with the major thrusts of the program. We analyzed the results from our preliminary studies on the packed-bed membrane reactor using the BASF methanol synthesis catalyst. We developed a quantitative model to describe the performance of the reactor.more » The effect of varying permeances and the effect of catalyst aging are being incorporated into the model. Secondly, we resumed our more- detailed parametric studies on selected non-sulfide Mo-based catalysts. Finally, we continue with the analysis of data from the kinetic study of a sulfided carbon-supported potassium-doped molybdenum-cobalt catalyst in the Rotoberty reactor. We have completed catalyst screening at UCC. The complete characterization of selected catalysts has been started. In Task 2, the fuel blends of alcohol and unleaded test gas 96 (UTG 96) have been made and tests have been completed. The testing includes knock resistance tests and emissions tests. Emissions tests were conducted when the engine was optimized for the particular blend being tested (i.e. where the engine produced the most power when running on the blend in question). The data shows that the presence of alcohol in the fuel increases the fuel`s ability to resist knock. Because of this, when the engine was optimized for use with alcohol blends, the engine produced more power and lower emission rates.« less

Cellulase production by Penicillium funiculosum and its application in the hydrolysis of sugar cane bagasse for second generation ethanol production by fed batch operation.

PubMed

Maeda, Roberto Nobuyuki; Barcelos, Carolina Araújo; Santa Anna, Lídia Maria Melo; Pereira, Nei

2013-01-10

This study aimed to produce a cellulase blend and to evaluate its application in a simultaneous saccharification and fermentation (SSF) process for second generation ethanol production from sugar cane bagasse. The sugar cane bagasse was subjected to pretreatments (diluted acid and alkaline), as for disorganizing the ligocellulosic complex, and making the cellulose component more amenable to enzymatic hydrolysis. The residual solid fraction was named sugar cane bagasse partially delignified cellulignin (PDC), and was used for enzyme production and ethanol fermentation. The enzyme production was performed in a bioreactor with two inoculum concentrations (5 and 10% v/v). The fermentation inoculated with higher inoculum size reduced the time for maximum enzyme production (from 72 to 48). The enzyme extract was concentrated using tangential ultrafiltration in hollow fiber membranes, and the produced cellulase blend was evaluated for its stability at 37 °C, operation temperature of the simultaneous SSF process, and at 50 °C, optimum temperature of cellulase blend activity. The cellulolytic preparation was stable for at least 300 h at both 37 °C and 50 °C. The ethanol production was carried out by PDC fed-batch SSF process, using the onsite cellulase blend. The feeding strategy circumvented the classic problems of diffusion limitations by diminishing the presence of a high solid:liquid ratio at any time, resulting in high ethanol concentration at the end of the process (100 g/L), which corresponded to a fermentation efficiency of 78% of the maximum obtainable theoretically. The experimental results led to the ratio of 380 L of ethanol per ton of sugar cane bagasse PDC. Copyright © 2012 Elsevier B.V. All rights reserved.

Lyotropic liquid crystal engineering moving beyond binary compositional space - ordered nanostructured amphiphile self-assembly materials by design.

PubMed

van 't Hag, Leonie; Gras, Sally L; Conn, Charlotte E; Drummond, Calum J

2017-05-22

Ordered amphiphile self-assembly materials with a tunable three-dimensional (3D) nanostructure are of fundamental interest, and crucial for progressing several biological and biomedical applications, including in meso membrane protein crystallization, as drug and medical contrast agent delivery vehicles, and as biosensors and biofuel cells. In binary systems consisting of an amphiphile and a solvent, the ability to tune the 3D cubic phase nanostructure, lipid bilayer properties and the lipid mesophase is limited. A move beyond the binary compositional space is therefore required for efficient engineering of the required material properties. In this critical review, the phase transitions upon encapsulation of more than 130 amphiphilic and soluble additives into the bicontinuous lipidic cubic phase under excess hydration are summarized. The data are interpreted using geometric considerations, interfacial curvature, electrostatic interactions, partition coefficients and miscibility of the alkyl chains. The obtained lyotropic liquid crystal engineering design rules can be used to enhance the formulation of self-assembly materials and provides a large library of these materials for use in biomedical applications (242 references).

Bacterial nanocellulose/Nafion composite membranes for low temperature polymer electrolyte fuel cells

NASA Astrophysics Data System (ADS)

Jiang, Gao-peng; Zhang, Jing; Qiao, Jin-li; Jiang, Yong-ming; Zarrin, Hadis; Chen, Zhongwei; Hong, Feng

2015-01-01

Novel nanocomposite membranes aimed for both proton-exchange membrane fuel cell (PEMFC) and direct methanol fuel cell (DMFC) are presented in this work. The membranes are based on blending bacterial nanocellulose pulp and Nafion (abbreviated as BxNy, where x and y indicates the mass ratio of bacterial cellulose to Nafion). The structure and properties of BxNy membranes are characterized by FTIR, SEM, TG, DMA and EIS, along with water uptake, swelling behavior and methanol permeability tests. It is found that the BxNy composite membranes with reinforced concrete-like structure show excellent mechanical and thermal stability regardless of annealing. The water uptake plus area and volume swelling ratios are all decreased compared to Nafion membranes. The proton conductivities of pristine and annealed B1N9 are 0.071 and 0.056 S cm-1, respectively, at 30 °C and 100% humidity. Specifically, annealed B1N1 exhibited the lowest methanol permeability of 7.21 × 10-7 cm2 s-1. Through the selectivity analysis, pristine and annealed B1N7 are selected to assemble the MEAs. The performances of annealed B1N7 in PEMFC and DMFC show the maximum power densities of 106 and 3.2 mW cm-2, respectively, which are much higher than those of pristine B1N7 at 25 °C. The performances of the pristine and annealed B1N7 reach a level as high as 21.1 and 20.4 mW cm-2 at 80 °C in DMFC, respectively.

Detailed Investigation of Separation Performance of a MMM for Removal of Higher Hydrocarbons under Varying Operating Conditions

PubMed Central

Mushardt, Heike; Müller, Marcus; Shishatskiy, Sergey; Wind, Jan; Brinkmann, Torsten

2016-01-01

Mixed-matrix membranes (MMMs) are promising candidates to improve the competitiveness of membrane technology against energy-intensive conventional technologies. In this work, MMM composed of poly(octylmethylsiloxane) (POMS) and activated carbon (AC) were investigated with respect to separation of higher hydrocarbons (C3+) from permanent gas streams. Membranes were prepared as thin film composite membranes on a technical scale and characterized via scanning electron microscopy (SEM) and permeation measurements with binary mixtures of n-C4H10/CH4 under varying operating conditions (feed and permeate pressure, temperature, feed gas composition) to study the influence on separation performance. SEM showed good contact and absence of defects. Lower permeances but higher selectivities were found for MMM compared to pure POMS membrane. Best results were obtained at high average fugacity and activity of n-C4H10 with the highest selectivity estimated to be 36.4 at n-C4H10 permeance of 12 mN3/(m2·h·bar). Results were complemented by permeation of a multi-component mixture resembling a natural gas application, demonstrating the superior performance of MMM. PMID:26927194

Influence of extreme concentrations of hydrophilic pore-former on reinforced polyethersulfone ultrafiltration membranes for reduction of humic acid fouling.

PubMed

Son, Moon; Kim, Hayoung; Jung, Junhyeok; Jo, Sungsoo; Choi, Heechul

2017-07-01

To address the issue of membrane fouling by ubiquitous humic substances, a hydrophilic pore-former-blended polyethersulfone UF membrane was successfully synthesized via the phase inversion method. For the first time, extremely high concentrations of polyvinylpyrrolidone (PVP), up to 20 wt%, were tested as the hydrophilic pore-former in order to determine the optimum concentration for humic acid fouling. Intrinsic membrane parameters such as permeability and selectivity were evaluated using a cross-flow UF filtration setup. Interestingly, as little as 1 wt% added PVP can significantly improve membrane permeability. That tiny amount of added PVP increased membrane flux to 1107 L/m 2 h·bar from zero flux, with over 90% rejection of humic acid. In addition, pure water permeation increased to over 2400 L/m 2 h·bar without sacrificing humic acid rejection (around 90%) when 10 wt% PVP was added; pure water permeation decreased to around 1000 L/m 2 h·bar as added PVP was increased to 20 wt%. The order of water flux increased with the amount of added PVP up to 20 wt% during humic acid fouling while maintaining membrane selectivity. However, the membrane with 10 wt% added PVP showed the best fouling resistance in terms of flux recovery ratio (98%), total flux loss, reversible fouling ratio, and irreversible fouling ratio. Therefore, the addition of 10 wt% PVP is recommended considering cleaning efficiency and the moderately high flux during humic acid fouling for field operation in wastewater reclamation and water treatment processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mixture Design Applied to the Development of Chickpea-Based Gluten-Free Bread with Attractive Technological, Sensory, and Nutritional Quality.

PubMed

Santos, Fernanda G; Fratelli, Camilly; Muniz, Denise G; Capriles, Vanessa D

2018-01-01

The aim of the study was utilized chickpea to create appealing, nutritious, and palatable gluten-free bread (GFB). The performance of chickpea flour (CF) in single and composite GFB formulations was studied with a mixture design and response surface methodology. Six simplex-centroid designs for 3 ingredients were used to identify the ideal proportions of CF in various blends with cassava starch (CS), maize starch (MS), potato starch (PS), and rice flour (RF) achieving the best physical properties. For each design, 3 single, 3 binary, and 3 ternary formulations were prepared. The results showed that CF alone is suitable for bread production, resulting in GFB with higher volume and crumb firmness and lower crumb moisture than single formulations of other raw materials. However, the interactions between CF and PS or CS enhanced the loaf volume and decreased the crumb firmness values. The GFB prepared with only CF was accepted (overall acceptability score of 7.1- on a 10-cm scale). Nevertheless, the composite formulations prepared with CF75:PS25 or CF75:CS25 (flour basis) received overall acceptability scores of 8.2, like those of their white GFB, prepared with RF50:PS50 blend (flour basis), and wheat bread counterparts, used as positive controls. Compared to white GFB, both composite formulations presented nearly a twofold increase in ash and protein contents and a threefold increase in total fiber content. These results show that blends of CF75:PS25 or CF75:CS25 can be used to develop GFB with a good physical and sensory properties, as well as an enhanced nutritional composition. Gluten-free bread (GFB) made with 75% chickpea flour (CF) blend with 25% potato or cassava starch showed improved total minerals, protein and dietary fiber content and bread quality characteristics. Therefore, CF is a valuable ingredient for food technologists in manufacturing better-tasting and healthy GFB, which is important for consumers with gluten-related disorders since GFB often lack nutrition content, appearance, texture, and mouthfeel. © 2017 Institute of Food Technologists®.

Theory of the formation of the electric double layer at the ion exchange membrane-solution interface.

PubMed

Moya, A A

2015-02-21

This work aims to extend the study of the formation of the electric double layer at the interface defined by a solution and an ion-exchange membrane on the basis of the Nernst-Planck and Poisson equations, including different values of the counter-ion diffusion coefficient and the dielectric constant in the solution and membrane phases. The network simulation method is used to obtain the time evolution of the electric potential, the displacement electric vector, the electric charge density and the ionic concentrations at the interface between a binary electrolyte solution and a cation-exchange membrane with total co-ion exclusion. The numerical results for the temporal evolution of the interfacial electric potential and the surface electric charge are compared with analytical solutions derived in the limit of the shortest times by considering the Poisson equation for a simple cationic diffusion process. The steady-state results are justified from the Gouy-Chapman theory for the diffuse double layer in the limits of similar and high bathing ionic concentrations with respect to the fixed-charge concentration inside the membrane. Interesting new physical insights arise from the interpretation of the process of the formation of the electric double layer at the ion exchange membrane-solution interface on the basis of a membrane model with total co-ion exclusion.

Physical properties and biocompatibility of oligochitosan membrane film as wound dressing.

PubMed

Ujang, Zanariah; Abdul Rashid, Ahmad Hazri; Suboh, Siti Kasmarizawaty; Halim, Ahmad Sukari; Lim, Chin Keong

2014-12-30

The physical and biological characteristics of oligochitosan (O-C) film, including its barrier and mechanical properties, in vitro cytotoxicity and in vivo biocompatibility, were studied to assess its potential use as a wound dressing. Membrane films were prepared from water-soluble O-C solution blended with various concentrations of glycerol to modify the physical properties of the films. In vitro and in vivo biocompatibility evaluations were performed using primary human skin fibroblast cultures and subcutaneous implantation in a rat model, respectively. Addition of glycerol significantly influenced the barrier and mechanical properties of the films. Water absorption capacity was in the range of 80%-160%, whereas water vapor transmission rate varied from 1,180 to 1,618 g/m2 per day. Both properties increased with increasing glycerol concentration. Tensile strength decreased while elongation at break increased with the addition of glycerol. O-C films were found to be noncytotoxic to human fibroblast cultures and histological examination proved that films are biocompatible. These results indicate that the membrane film from O-C has potential application as a wound-dressing material.

Laminin- and basement membrane-polycaprolactone blend nanofibers as a scaffold for regenerative medicine.

PubMed

Neal, Rebekah A; Lenz, Steven M; Wang, Tiffany; Abebayehu, Daniel; Brooks, Benjamin P C; Ogle, Roy C; Botchwey, Edward A

2014-09-01

Mimicking one or more components of the basement membrane (BM) holds great promise for overcoming insufficiencies in tissue engineering therapies. We have electrospun laminin nanofibers (NFs) isolated from the murine Engelbreth-Holm Swarm (EHS) tumor and evaluated them as a scaffold for embryonic stem cell culture. Seeded human embryonic stem cells were found to better maintain their undifferentiated, colony environment when cultured on laminin NFs compared to laminin mats, with 75% remaining undifferentiated on NFs. Mouse embryonic stem cells cultured on 10% laminin-polycaprolactone (PCL) NFs maintained their colony formation for twice as long without passage compared to those on PCL or gelatin substrates. In addition, we have established a protocol for electrospinning reconstituted basement membrane aligned (RBM)-PCL NFs within 10° of angular deviation. Neuron-like PC12 cells show significantly greater attachment (p < 0.001) and percentage of neurite-extending cells in vitro on 10% RBM-PCL NFs when compared to 1% and 0% RBM-PCL NFs (p < 0.015 and p < 0.001, respectively). Together, these results implicate laminin- and RBM-PCL scaffolds as a promising biomimetic substrate for regenerative medicine applications.

Novel Composite Proton Exchange Membrane with Connected Long-Range Ionic Nanochannels Constructed via Exfoliated Nafion-Boron Nitride Nanocomposite.

PubMed

Jia, Wei; Tang, Beibei; Wu, Peiyi

2017-05-03

Nafion-boron nitride (NBN) nanocomposites with a Nafion-functionalized periphery are prepared via a convenient and ecofriendly Nafion-assisted water-phase exfoliation method. Nafion and the boron nitride nanosheet present strong interactions in the NBN nanocomposite. Then the NBN nanocomposites were blended with Nafion to prepare NBN Nafion composite proton exchange membranes (PEMs). NBN nanocomposites show good dispersibility and have a noticeable impact on the aggregation structure of the Nafion matrix. Connected long-range ionic nanochannels containing exaggerated (-SO 3 - ) n ionic clusters are constructed during the membrane-forming process via the hydrophilic and H-bonding interactions between NBN nanocomposites and Nafion matrix. The addition of NBN nanocomposites with sulfonic groups also provides additional proton transportation spots and enhances the water uptake of the composite PEMs. The proton conductivity of the NBN Nafion composite PEMs is significantly increased under various conditions relative to that of recast Nafion. At 80 °C-95% relative humidity, the proton conductivity of 0.5 NBN Nafion is 0.33 S·cm -1 , 6 times that of recast Nafion under the same conditions.

Hyaluronan/Tween 80-assisted synthesis of silver nanoparticles for biological application

NASA Astrophysics Data System (ADS)

Li, Hui-Jun; Zhang, An-Qi; Sui, Li; Qian, Dong-Jin; Chen, Meng

2015-02-01

Water-soluble and well-stabilized silver nanoparticles (NPs) of small size have been synthesized using hyaluronan (HA) and Tween 80 as reducing and stabilizing agents. The effect of reaction conditions on the formation process of silver NPs was studied, and an aggregative growth mechanism of the silver NPs dominated in HA/Tween 80 system at pH 12 has been proposed. The obtained Ag NPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy. Moreover, the stability of the HA-Tween 80-silver NPs in normal saline was also studied, and a flexible blend membrane containing chitosan, gelatin, and the HA-Tween 80-silver NPs was prepared for further biological applications. Due to the high specific surface area and improved stability of silver NPs, the chitosan-gelatin-silver membrane has shown high antibacterial activity for strains of Escherichia coli. The cell viability tests indicate that the polymer membrane is non-cytotoxic to HepG2 cells, which might be attributed to its good biocompatibility.

A Study on the Kinetics of a Disorder-to-Order Transition Induced by Alkyne/Azide Click Reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

X Wei; L Li; J Kalish

2011-12-31

The kinetics of binary blends of poly(ethylene oxide)-block-poly(n-butyl methacrylate-random-propargyl methacrylate) (PEO-b-P(nBMA-r-PgMA)) diblock copolymer and Rhodamine B azide was investigated during a disorder-to-order transition induced by alkyne/azide click reaction. The change in the domain spacing and conversion of reactants as a function of annealing time were investigated by in situ small-angle X-ray scattering (SAXS) and infrared spectroscopy (IR), suggesting several kinetic processes with different time scales during thermal annealing. While a higher conversion can be realized by extending the annealing time, the microphase-separated morphology is independent of the annealing conditions, as long as both the reagents and final products have enoughmore » mobility.« less

Molecularly thin fluoro-polymeric nanolubricant films: tribology, rheology, morphology, and applications.

PubMed

Chung, Pil Seung; Jhon, Myung S; Choi, Hyoung Jin

2016-03-21

Molecularly thin perfluoropolyether (PFPE) has been used extensively as a high-performance lubricant in various applications and, more importantly, on carbon overcoats to enhance the reliability and lubrication of micro-/nanoelectro-mechanical systems, where the tribological performance caused by its molecular architecture is a critical issue, as are its physical properties and rheological characteristics. This Highlight addresses recent trends in the development of fluoro-polymeric lubricant films with regard to their tribology, rheology, and physio-chemical properties as they relate to heat-assisted magnetic recording. Nanorheology has been employed to examine the dynamic response of nonfunctional and functional PFPEs, while the viscoelastic properties of nanoscale PFPE films and the relaxation processes as a function of molecular structure and end-group functionality were analyzed experimentally; furthermore, the characteristics of binary blends were reported.

Investigation of H2S separation from H2S/CH4 mixtures using functionalized and non-functionalized vertically aligned carbon nanotube membranes

NASA Astrophysics Data System (ADS)

Gilani, Neda; Towfighi, Jafar; Rashidi, Alimorad; Mohammadi, Toraj; Omidkhah, Mohammad Reza; Sadeghian, Ahmad

2013-04-01

Separation of H2S from binary mixtures of H2S/CH4 using vertically aligned carbon nanotube membranes fabricated in anodic aluminum oxide (AAO) template was studied experimentally. Carbon nanotubes (CNTs) were grown in five AAO templates with different pore diameters using chemical vapor deposition, and CNT/AAO membranes with tubular carbon nanotube structure and open caps were selected for separation of H2S. For this, two tubular CNT/AAO membranes were fabricated with the CNT inner diameters of 23 and 8 nm. It was found that permeability and selectivity of the membrane with inner diameter of 23 nm for CNT were independent of upstream feed pressure and H2S feed concentration unlike that of CNT having an inner diameter of 8 nm. Selectivity of these membranes for separation of H2S was obtained in the ranges of 1.36-1.58 and 2.11-2.86, for CNTs with internal diameters of 23 and 8 nm, respectively. In order to enhance the separation of H2S from H2S/CH4 mixtures, dodecylamine was used to functionalize the CNT/AAO membrane with higher selectivity. The results showed that for amido-functionalized membrane, both upstream feed pressure and H2S partial pressure in the feed significantly increased H2S permeability, and selectivity for H2S being in the range of 3.0-5.57 respectively.

Toxicity of binary mixtures of metal oxide nanoparticles to Nitrosomonas europaea.

PubMed

Yu, Ran; Wu, Junkang; Liu, Meiting; Zhu, Guangcan; Chen, Lianghui; Chang, Yan; Lu, Huijie

2016-06-01

Although the widely used metal oxide nanoparticles (NPs) titanium dioxide NPs (n-TiO2), cerium dioxide NPs (n-CeO2), and zinc oxide NPs (n-ZnO) have been well known for their potential cytotoxicities to environmental organisms, their combined effects have seldom been investigated. In this study, the short-term binary effect of n-CeO2 and n-TiO2 or n-ZnO on a model ammonia oxidizing bacterium, Nitrosomonas europaea were evaluated based on the examinations of cells' physiological, metabolic, and transcriptional responses. The addition of n-TiO2 mitigated the negative effect of more toxic n-CeO2 and the binary toxicity (antagonistic toxicity) of n-TiO2 and n-CeO2 was generally lower than the single NPs induced one. While the n-CeO2/n-ZnO mixture exerted higher cytotoxicity (synergistic cytotoxicity) than that from single NPs. The increased addition of the less toxic n-CeO2 exaggerated the binary toxicity of n-CeO2/n-ZnO mixture although the solubility of n-ZnO was not significantly affected, which excluded the contribution of the dissolved Zn ions to the enhancement of the combined cytotoxicity. The cell membrane disturbances and NP internalizations were detected for all the NP impacted cultures and the electrostatic interactions among the two distinct NPs and the cells were expected to play a key role in mediating their direct contacts and the eventual binary nanotoxicity to the cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

Detection of Reflection Features in the Neutron Star Low-mass X-Ray Binary Serpens X-1 with NICER

NASA Astrophysics Data System (ADS)

Ludlam, R. M.; Miller, J. M.; Arzoumanian, Z.; Bult, P. M.; Cackett, E. M.; Chakrabarty, D.; Dauser, T.; Enoto, T.; Fabian, A. C.; García, J. A.; Gendreau, K. C.; Guillot, S.; Homan, J.; Jaisawal, G. K.; Keek, L.; La Marr, B.; Malacaria, C.; Markwardt, C. B.; Steiner, J. F.; Strohmayer, T. E.

2018-05-01

We present Neutron Star Interior Composition Explorer (NICER) observations of the neutron star (NS) low-mass X-ray binary Serpens X-1 during the early mission phase in 2017. With the high spectral sensitivity and low-energy X-ray passband of NICER, we are able to detect the Fe L line complex in addition to the signature broad, asymmetric Fe K line. We confirm the presence of these lines by comparing the NICER data to archival observations with XMM-Newton/Reflection Grating Spectrometer (RGS) and NuSTAR. Both features originate close to the innermost stable circular orbit (ISCO). When modeling the lines with the relativistic line model RELLINE, we find that the Fe L blend requires an inner disk radius of {1.4}-0.1+0.2 R ISCO and Fe K is at {1.03}-0.03+0.13 R ISCO (errors quoted at 90%). This corresponds to a position of {17.3}-1.2+2.5 km and {12.7}-0.4+1.6 km for a canonical NS mass ({M}NS}=1.4 {M}ȯ ) and dimensionless spin value of a = 0. Additionally, we employ a new version of the RELXILL model tailored for NSs and determine that these features arise from a dense disk and supersolar Fe abundance.

Molecular Grafting of Fluorinated and Nonfluorinated Alkylsiloxanes on Various Ceramic Membrane Surfaces for the Removal of Volatile Organic Compounds Applying Vacuum Membrane Distillation.

PubMed

Kujawa, Joanna; Al-Gharabli, Samer; Kujawski, Wojciech; Knozowska, Katarzyna

2017-02-22

Four main tasks were presented: (i) ceramic membrane functionalization (TiO 2 5 kDa and 300 kDa), (ii) extended material characterization (physicochemistry and tribology) of pristine and modified ceramic samples, (iii) evaluation of chemical and mechanical stability, and finally (iv) assessment of membrane efficiency in vacuum membrane distillation applied for volatile organic compounds (VOCs) removal from water. Highly efficient molecular grafting with four types of perfluoroalkylsilanes and one nonfluorinated agent was developed. Materials with controllable tribological and physicochemical properties were achieved. The most meaningful finding is associated with the applicability of fluorinated and nonfluorinated grafting agents. The results of contact angle, hysteresis of contact angle, sliding angle, and critical surface tension as well as Young's modulus, nanohardness, and adhesion force for grafting by these two modifiers are comparable. This provides insight into the potential applicability of environmental friendly hydrophobic and superhydrophobic surfaces. The achieved hydrophobic membranes were very effective in the removal of VOCs (butanol, methyl-tert-butyl ether, and ethyl acetate) from binary aqueous solutions in vacuum membrane distillation. The correlation between membrane effectiveness and separated solvent polarity was compared in terms of material properties and resistance to the wetting (kinetics of wetting and in-depth liquid penetration). Material properties were interpreted considering Zisman theory and using Kao diagram. The significant influence of surface chemistry on the membrane performance was noticed (5 kDa, influence of hydrophobic nanolayer and separation controlled by solution-diffusion model; 300 kDa, no impact of surface chemistry and separation controlled by liquid-vapor equilibrium).

Multiple patterns of polymer gels in microspheres due to the interplay among phase separation, wetting, and gelation.

PubMed

Yanagisawa, Miho; Nigorikawa, Shinpei; Sakaue, Takahiro; Fujiwara, Kei; Tokita, Masayuki

2014-11-11

We report the spontaneous patterning of polymer microgels by confining a polymer blend within microspheres. A poly(ethylene glycol) (PEG) and gelatin solution was confined inside water-in-oil (W/O) microdroplets coated with a layer of zwitterionic lipids: dioleoylphosphatidylethanolamine (PE) and dioleoylphosphatidylcholine (PC). The droplet confinement affected the kinetics of the phase separation, wetting, and gelation after a temperature quench, which determined the final microgel pattern. The gelatin-rich phase completely wetted to the PE membrane and formed a hollow microcapsule as a stable state in the PE droplets. Gelation during phase separation varied the relation between the droplet size and thickness of the capsule wall. In the case of the PC droplets, phase separation was completed only for the smaller droplets, wherein the microgel partially wetted the PC membrane and had a hemisphere shape. In addition, the temperature decrease below the gelation point increased the interfacial tension between the PEG/gelatin phases and triggered a dewetting transition. Interestingly, the accompanying shape deformation to minimize the interfacial area was only observed for the smaller PC droplets. The critical size decreased as the gelatin concentration increased, indicating the role of the gel elasticity as an inhibitor of the deformation. Furthermore, variously patterned microgels with spherically asymmetric shapes, such as discs and stars, were produced as kinetically trapped states by regulating the incubation time, polymer composition, and droplet size. These findings demonstrate a way to regulate the complex shapes of microgels using the interplay among phase separation, wetting, and gelation of confined polymer blends in microdroplets.