Scale Up and Validation of Novel Tri-Bore PVDF Hollow Fiber Membranes for Membrane Distillation Application in Desalination and Industrial Wastewater Recycling.

Novel tri-bore polyvinylidene difluoride (PVDF) hollow fiber membranes (TBHF) were scaled-up for fabrication on industrial-scale hollow fiber spinning equipment, with the objective of validating the membrane technology for membrane distillation (MD) applications in areas such as desalination, resource recovery, and zero liquid discharge. The membrane chemistry and spinning processes were adapted from a previously reported method and optimized to suit large-scale production processes with the objective of translating the technology from lab scale to pilot scale and eventual commercialization. The membrane process was successfully optimized in small 1.

Development and Industrial-Scale Fabrication of Next-Generation Low-Energy Membranes for Desalination.

Spiral-wound modules have been the most common configuration of packing flat-sheet membranes since the early development of polyamide (PA) membranes for water treatment applications. Conventional spiral-wound modules (SWMs) for desalination applications typically consist of several leaf sets, with each leaf set comprising feed spacers, membranes, and a permeate carrier (PC) wrapped around a permeate-collecting tube. The membrane area that can be packed into a given module diameter is limited by the overall leaf set thickness, restricting module productivity for a given membrane permeability.

Novel Sandwich-Structured Hollow Fiber Membrane for High-Efficiency Membrane Distillation and Scale-Up for Pilot Validation.

Hollow fiber membranes were produced from a commercial polyvinylidene fluoride (PVDF) polymer, Kynar HSV 900, with a unique sandwich structure consisting of two sponge-like layers connected to the outer and inner skin layers while the middle layer comprises macrovoids. The sponge-like layer allows the membrane to have good mechanical strength even at low skin thickness and favors water vapor transportation during vacuum membrane distillation (VMD). The middle layer with macrovoids helps to significantly reduce the trans-membrane resistance during water vapor transportation from the feed side to the permeate side.

Self-assembly of block copolymer micelles: synthesis via reversible addition-fragmentation chain transfer polymerization and aqueous solution properties.

Poly(hexafluorobutyl methacrylate) (PHFBMA) homopolymer was synthesized by reversible addition-fragmentation chain transfer (RAFT)-mediated living radical polymerization in the presence of cyano-2-propyl dithiobenzoate (CPDB) RAFT agent. A block copolymer of PHFBMA-poly(propylene glycol acrylate) (PHFBMA-b-PPGA) with dangling poly(propylene glycol) (PPG) side chains was then synthesized by using CPDB-terminated PHFBMA as a macro-RAFT agent. The amphiphilic properties and self-assembly of PHFBMA-b-PPGA block copolymer in aqueous solution were investigated by dynamic and static light scattering (DLS and SLS) studies, in combination with fluorescence spectroscopy and transmission electron microscopy (TEM).

Time-dependent polymerization kinetic study and the properties of hybrid polymers with functional silsesquioxanes.

Methacrylate-functionalized cubic silsesquioxane homopolymers [p(MA-CSSQ)] were synthesized by reversible addition-fragmentation chain transfer (RAFT)-mediated living radical polymerization in the presence of dodecyl(dimethylacetic acid)trithiocarbonate (DDTA) chain transfer agent, and their polymerization kinetics were studied. The DDTA-terminated p(MA-CSSQ) was then employed as a macro-RAFT agent in the polymerization of methylmethacrylate (MMA) for the synthesis of a brushlike p(MA-CSSQ)-b-PMMA block copolymer. The kinetics study of p(MA-CSSQ) showed that the monomer to polymer conversion, evaluated by (1)H NMR, was found to be approximately 80% with the maximum number average molecular weight (M(n)) of 24000 and 32300 Da, for the [MA-CSSQ]/[DDTA] ratios of 100 and 200, respectively, as determined by gel permeation chromatography (GPC).

Multilayer buildup and biofouling characteristics of PSS-b-PEG containing films.

Thin films exhibiting protein resistance are of interest in diverse areas, ranging from low fouling surfaces in biomedicine to marine applications. Herein, we report the preparation of low protein and cell binding multilayer thin films, formed by the alternate deposition of a block copolymer comprising polystyrene sulfonate and poly(poly(ethylene glycol) methyl ether acrylate) (PSS-b-PEG), and polyallylamine hydrochloride (PAH). Film buildup was followed by quartz crystal microgravimetry (QCM), which showed linear growth and a high degree of hydration of the PSS-b-PEG/PAH films.

Synthesis and Self-Assembly of pH-Responsive Amphiphilic Poly(dimethylaminoethyl methacrylate)-block-Poly(pentafluorostyrene) Block Copolymer in Aqueous Solution.

We report the synthesis of a novel pH-responsive amphiphilic block copolymer poly(dimethylaminoethyl methacrylate)-block-poly(pentafluorostyrene) (PDMAEMA-b-PPFS) using RAFT-mediated living radical polymerization. Copolymer micelle formation, in aqueous solution, was investigated using fluorescence spectroscopy, static and dynamic light scattering (SLS and DLS), and transmission electron microscopy (TEM). DLS and SLS measurements revealed that the diblock copolymers form spherical micelles with large aggregation numbers, N(agg)  ≈ 30 where the dense PPFS core is surrounded by dangling PDMAEMA chains as the micelle corona.

Micelle formation of amphiphilic polystyrene-b-poly(N-vinylpyrrolidone) diblock copolymer in methanol and water-methanol binary mixtures.

The micelle formation by the amphiphilic polystyrene-block-poly(N-vinylpyrrolidone) (PS48-b-PNVP99) copolymer is investigated in methanol and water-methanol binary mixtures of various compositions using 1H NMR, fluorescence spectroscopy, static/dynamic light scattering (SLS/DLS), and transmission electron microscopy (TEM). Critical micelle concentrations (cmc) are determined by employing fluorescence spectroscopy and DLS measurements. The cmc of the PS48-b-PNVP99 block copolymer increases with increasing methanol content in the water-methanol binary mixtures, suggesting that methanol is a better solvent for the PS48-b-PNVP99 block copolymer than water-methanol mixtures or pure water.

Synthesis, multilayer film assembly, and capsule formation of macromolecularly engineered acrylic acid and styrene sulfonate block copolymers.

We report the use of copolymers synthesized with specific block ratios of weakly and strongly charged groups for the preparation of stable, pH-responsive multilayers. In this study, we utilized reversible addition-fragmentation chain transfer (RAFT) polymerization in the synthesis of novel pH-sensitive copolymers comprising block domains of acrylic acid (AA) and styrene sulfonate (SS) groups. The PAA x- b-SS y copolymers, containing 37%, 55%, and 73% of AA groups by mass (denoted as PAA 37- b-SS 63, PAA 55- b-SS 45, and PAA 73- b-SS 27, respectively), were utilized to perform stepwise multilayer assembly in alternation with poly(allylamine hydrochloride), PAH.

The antifouling and fouling-release performance of hyperbranched fluoropolymer (HBFP)-poly(ethylene glycol) (PEG) composite coatings evaluated by adsorption of biomacromolecules and the green fouling alga Ulva.

Cross-linked hyperbranched fluoropolymer (HBFP) and poly(ethylene glycol) (PEG) amphiphilic networks with PEG weight percentages of 14% (HBFP-PEG14), 29% (HBFP-PEG29), 45% (HBFP-PEG45), and 55% (HBFP-PEG55) were prepared on 3-aminopropyl)triethoxysilane (3-APS) functionalized microscope glass slides for marine antifouling and fouling-release applications. The surface-free energies (gamma(s)), polar (gamma(s)(p) and gamma(s)(AB)), and dispersion (gamma(s)(d) and gamma(s)(LW)) components were evaluated using advancing contact angles by two-liquid geometric-mean and three-liquid Lifshitz-van der Waals acid-base approaches. The HBFP coating exhibited a low surface energy of 22 mJ/m(2), while the gamma(s) and gamma(s)(p) of the cross-linked HBFP-PEG coatings increased proportionally with the PEG weight percentages in the networks.

The effects of high (sodium meglumine diatrizoate, Renografin-76) and low osmolar (sodium meglumine ioxaglate, Hexabrix) radiographic contrast media on diastolic function during left ventriculography in patients.

Although a majority of studies indicate superior hemodynamic and clinical profiles of low osmolar compared with high osmolar contrast media, the effect of these agents on diastolic left ventricular function has not been examined. We prospectively examined hemodynamic, electrocardiographic, and echocardiographic indices of left ventricular function in patients undergoing contrast ventriculography with a high osmolar, ionic, monomeric contrast, diatrizoate (Renografin-76) compared with a low osmolar, ionic, dimeric contrast, ioxaglate (Hexabrix). Thirty patients were randomized to each group.

Effects of aging on left ventricular structure and function.

To better characterize the cardiac structural and functional changes that are associated with aging, Doppler-echocardiography was performed on 23 young (mean age, 25 years) and 30 old (mean age, 70 years) healthy normotensive subjects. Left ventricular cavity dimensions and wall thickness were determined and left ventricular mass index was calculated from M-mode echocardiograms. Stroke volume was calculated from Doppler-measured aortic flow.

Echocardiographic evaluation of cardiac structure and function in elderly subjects with isolated systolic hypertension.

One hundred four participants in the Systolic Hypertension in the Elderly Program (SHEP) trial (mean age 71 +/- 6 years) were examined by Doppler echocardiography to gain information on the cardiac structural and functional alterations in isolated systolic hypertension. Participants had a systolic blood pressure greater than 160 mm Hg with diastolic blood pressure less than 90 mm Hg and were compared with 55 age-matched normotensive control subjects. Left ventricular mass index was significantly higher in the participants than in the normotensive subjects (103 +/- 28 versus 87 +/- 23 g/m2, p = 0.

Preliminary experience with 5 and 6 French diagnostic catheters as guiding catheters for coronary angioplasty.

With the reduction in profile of balloon dilation catheters, until recently, it has been the internal dimensions and performance of the guiding catheter that has mandated the use of 7, 8 or 9 French (F) systems for the performance of percutaneous transluminal coronary angioplasty (PTCA). A new 5F catheter design (Sherwood Medical Co., St.

Ventricular arrhythmia due to intracoronary papaverine: analysis of QT intervals and coronary vasodilatory reserve.

Intracoronary papaverine commonly produces striking QT interval prolongation with rare but serious ventricular dysrhythmias reported. Because of 3 cases of severe papaverine-induced dysrhythmia in our laboratory, QT intervals and hemodynamic and intracoronary velocity data collected during intracoronary papaverine administration were retrospectively reviewed in 34 patients; 20 patients with angiographically normal coronary arteries (group 1) and 14 patients (group 2) before and (group 2) after single-vessel left coronary angioplasty. QT intervals increased from 394 +/- 44 to 464 +/- 73 msec, 414 +/- 47 to 504 +/- 95 msec, and 410 +/- 41 to 486 +/- 75 msec for groups 1 and 2 before and after angioplasty, respectively (all P less than 0.

Effect of abruptly increased intrathoracic pressure on coronary blood flow velocity in patients.

To assess the effects of abruptly increased intrathoracic pressure on coronary blood flow, arterial pressure, heart rate, and intracoronary Doppler blood flow velocity were measured continuously during cough(s) and again during the four phases of the Valsalva maneuver in 14 patients. Coughing significantly increased the systolic pressure (137 +/- 25 to 176 +/- 30 mm Hg), diastolic pressure (72 +/- 10 to 84 +/- 18 mm Hg), and arterial pulse pressure (65 +/- 27 to 92 +/- 35 mm Hg), with no change in heart rate. The mean coronary flow velocity decreased (17 +/- 10 to 14 +/- 12 cm/sec, p less than 0.

Increases in coronary vein CO2 during cardiac resuscitation.

We investigated the aortic, mixed venous, and great cardiac vein acid-base changes in eight domestic pigs during cardiac arrest produced by ventricular fibrillation and during cardiopulmonary resuscitation (CPR). The great cardiac vein PCO2 increased from a control value of 52 +/- 2 to 132 +/- 28 (SD) Torr during CPR, whereas the arterial PCO2 was unchanged (39 +/- 4 vs. 38 +/- 4).

Immediate and short-term effects of aortic balloon valvuloplasty on left ventricular diastolic function and filling in humans.

The effect of aortic balloon valvuloplasty on left ventricular diastolic function and filling was investigated in 44 adult patients with severe aortic stenosis. Two-dimensional and Doppler echocardiography was performed in all patients before and 24 h after valvuloplasty. In 19 patients (short-term group) repeat studies were performed at 3 (n = 2) and 6 (n = 17) months.

Mechanism of blood flow generated by precordial compression during CPR. I. Studies on closed chest precordial compression.

The mechanism of forward flow produced by precordial compression during CPR was investigated with the aid of echocardiographic and hemodynamic measurements in anesthetized, mechanically ventilated domestic pigs. Both mitral and tricuspid valves opened during compression diastole and closed during compression systole. Valve motion persisted throughout resuscitation in 17 of 22 animals which were hemodynamically resuscitated.

Effects of pharmacologic coronary hyperemia on echocardiographic left ventricular function in patients with single vessel coronary artery disease.

To assess whether pharmacologic coronary vasodilation could provoke new left ventricular wall motion abnormalities in patients with single vessel coronary artery disease, systemic hemodynamics, coronary blood flow velocity and left ventricular wall motion were measured by two-dimensional echocardiography during administration of 10 mg of intracoronary papaverine in 14 patients before and again immediately after left coronary angioplasty (group 1). As a comparison with an intravenous method, left ventricular wall motion was analyzed after 0.56 mg/kg body weight of intravenous dipyridamole in a separate group of 13 patients with single vessel coronary disease (group 2).