William Mickols

We have used differential polarization microscopy, which provides images of linear dichroism, to measure the percentage of aligned hemoglobin (Hb) in 1086 deoxygenated red blood cells from subjects with sickle cell anemia. The percentage was found to be only slightly dependent on the speed of deoxygenation, thus showing that the percentage of aligned Hb was thermodynamically controlled (as has been found previously for the percentage of polymerized Hb in vitro). A slight decrease in the percentage of aligned Hb due to increasing speed of deoxygenation is primarily due to the increase in the number of cells containing no detectable aligned Hb. This class of cells was also the most variable between the different subjects studied. We were able to identify two other groups of cells that contain different numbers of domains of aligned Hb and show that these groups contain statistically different percentages of aligned Hb. The differences between these classes of cells was shown to be primarily due to different numbers of initial nucleation sites within each cell. It appears that the presence of preformed nucleation sites within cells at ambient oxygen tensions results in the thermodynamic control of aligned Hb polymer.

La presente invention concerne un procede de fabrication d'une membrane de polyamide composite comprenant un support poreux et une couche mince de polyamide, le procede comprenant l'etape consistant a appliquer une solution polaire comprenant un monomere d'amine polyfonctionnelle et une solution non polaire comprenant un monomere d'halogenure d'acyle polyfonctionnelle sur une surface du support poreux et polymeriser a l'interface les monomeres pour former une couche mince de polyamide, le procede etant caracterise par l'etape consistant a appliquer une solution non polaire comprenant un compose d'amine tertiaire acyclique aliphatique sur le support.

La presente invention concerne des membranes composites, comprenant un revetement constitue de composes d'oxyde de polyalkylene et de biguanide, ainsi que divers procedes de realisation et d'utilisation associes. Dans un mode de realisation, la membrane composite comprend une mince couche de film polyamide, comprenant un revetement constitue d'un produit de reaction d'un compose d'oxyde de polyalkylene et d'un compose de type biguanide. Dans un autre mode de realisation, le revetement comprend un polymere comprenant des motifs repetes d'oxyde d'alkylene et un ou plusieurs groupes fonctionnels de biguanide.

Des membranes composites qui presentent une resistance longue duree a la contamination par des agents biologiques comprennent un support poreux et une couche selective en polyamide reticule qui presente une surface externe, ladite couche selective comprenant un polyoxyde d'alkylene (PAO) ramifie arrime a sa surface externe. Le polymere PAO ramifie presente typiquement une structure moleculaire de type brosse, et est fabrique par polymerisation d'un macromonomere PAO de formule (I) suivante : RO-[(CHR')n- 0]m- V ou R represente l'atome d'hydrogene ou un groupement aliphatique ou aromatique en Q-2O, V represente un groupement quelconque contenant un acide polymerisable, chacun des groupements R' represente independamment un atome d'hydrogene ou un groupement alkyle a chaine courte, n represente un entier compris entre 1 et 6 inclus, et m represente un entier compris entre 1 et environ 200. Le groupement de l'extremite α peut etre polymerise ou copolymer...

Differential polarization microscopy is the name given to a group of microscopic techniques that create images using changes in the polarization of light or changes in the amount of polarized light (linear or circular) transmitted or scattered by an object. This will be made clearer by first examining several better-known microscopic techniques. The classical example of polarization microscopy is that based on detecting a change in linear polarization. Using various optical analyses, we can show that there are eight different optical transmission effects as well as an equal number of scattering effects that can be detected in this manner. Many different polarization effects can produce images in interference microscopy and this is also true of microscopic techniques based on any phase effects (phase shear, holography, true phase, etc.). These techniques all generate an image by ‘comparing’ two light beams. In the interference microscope this may be done when one beam has a different...

La presente invention concerne des membranes composites comportant un revetement a base de composes d'acetophenone et d'oxyde de polyalkylene, ainsi que divers procedes de fabrication et d'utilisation de celles-ci. Selon un mode de realisation, ladite membrane composite comprend une couche constituee d'un mince film de polyamide comportant un revetement a base du produit reactionnel d'un compose d'oxyde de polyalkylene et d'un compose d'acetophenone. Selon un autre mode de realisation, ledit revetement comprend un polymere comportant des motifs recurrents d'oxyde d'alkylene et un ou plusieurs groupes fonctionnels acetophenone.

Biofouling of reverse osmosis membranes is one of the main reasons for the flux decline in water reuse applications in the filtration industry. A simple screening approach to evaluate such membranes for their propensity to biofouling and a means of removing biofoulants, without changing surface physicochemical properties, would be of benefit to this sector. The objectives of this research are to investigate the mode of action of Subtilisin protease- and lipase-based enzymatic cleaning of thin-film composite reverse osmosis membrane biofoulants, and characterise the effects of the biofilm-resistant membrane surfaces by using cryosectioning of the membrane with biofilm on its surface. The first instalment of this article, which appears here, provides an introduction to the research, the materials and methods used and the first part of the results, which discusses biofilm formation, and quantitative measurements and visualisation of biofoulants on reverse osmosis membranes. Part II wil...

The transport model for reverse-osmosis membranes and nanofiltration membranes was reformulated to include the large changes in the chemical activity of solutes in solutions employed to test these membranes. The approach presented herein uses a solution-diffusion model for membrane transport and a more accurate representation of the test solution and the partitioning of the solutes into the membrane. This approach corrects the simplifying assumption in the Merten model of highly diluted solutions and predicts the large changes in the passage of solutes due to increased solute concentration. These changes are due to the large changes in the activity coefficients of the solutes outside the very dilute regions. These changes can significantly influence salt- and water-transport coefficients (e.g., A- and B-values).

A modified polyamide membrane and methods of making and using the same. The present invention is a polyamide membrane predetermined modifier, for example, but not limited to certain oxazoline and / or the compound of thiazoline system, many aspects, including a method comprising contacting a derivative thereof and polymers It encompasses. In one embodiment, the surface of the polyamide membrane, optionally heat and subsequently coated with a solution containing a polyoxazoline and optionally polyalkylene oxide material. Preferred embodiment, improved performance, for example, a given species (e.g., sodium chloride and / or boron oxide, for example, boric acid or the various borates) increasing rejection, reduction of pollution, improvement of the anti-microbial properties, and / or it can exhibit an improvement in storage stability.

A composite membrane and method for making the same, comprising a porous support and a crosslinked polyamide surface. The subject membrane provides improved flux and/or rejection rates. The subject membrane is further capable of operating at lower operating pressures. The subject method includes reacting a polyfunctional amine with a polyfunctional acyl halide to form a polyamide. The method includes the step of contacting a phosphorous containing compound with the polyfunctional acyl halide prior to and/or during the reaction between the polyfunctional acyl halide and a polyfunctional amine. The subject process is easily adapted to commercial scale manufacturing processes and is particularly suited for making nanofiltration and reverse osmosis composite membranes.

This chapter reviews the chemical stability of artificial membranes synthesized for use in reverse osmosis (RO) and nanofiltration. The synthetic work was often aimed at obtaining chlorine-resistant polyamide membranes with similar performance to the FT-30 membrane. The FT-30 membrane is made from the interfacial synthesis of 1,3-phenylene diamine (MPD) and the 1,3,5-benzene triacid chloride. This included primarily work on aromatic polyamides and also related polymers such as polyureas, polyesters, polyurethanes, and so on. Solution synthetic work showed a wide variety of polyamide linkages stable to chlorine and chlorine oxide attack. Membranes made from these synthetic routes were not chlorine or chlorine oxide stable. In the cases studied in detail, Koval et al. determined that the amine end groups left over from the synthesis of these polymers produced chloramine derivatives and produced other chlorine derivatives that would be similar to those reported from the digestion of chlorinated aromatic polyamide RO membranes. There were large changes in the reported flux from membranes made with different polymer classes. Some of these changes in flux could be attributed to the change in hydrophobicity of the polymers. The hydrophobicity was estimated by the octanol–water partition coefficient of representative polymer fragments. The review included a study of the relatively large expected change in p K of the expected amine end groups left over from the synthesis and if they substantially changed the extent of chlorination. The data showed that these changes may affect the rate of chlorination but they were unable to substantively affect the final chlorine/chlorine oxide stability of aromatic polyamide membranes. The wide variety of polyamides produced and tested for membrane performance encompasses 25 years of synthetic work and a wide variety of different possible polymers. Estimates of the end group p K and how they affect apparent rejection at near-neutral pHs show why the fully aromatic polyamide polymers epitomized by the FT-30 aromatic polyamide have an optimum structure for use in the majority of sources for drinking water.

Abstract The activity coefficients and equations for transport through nanofiltration (NF) and reverse osmosis (RO) membranes were derived to determine the contribution of the heat of vaporization, molar volume, activation energy (diffusion), thermal expansion, and liquid- and vapor-phase compression. These equations have been derived for pure substances; hence, the measured deviations were obtained from the membrane itself. The inclusion of these effects provides a more accurate prediction of membrane transport than that provided by current models. The model presented herein accurately determined fluxes over temperature and pressure ranges for four different membranes, which the Merten model failed to determine. The transport activity model was applied to water, ethanol, methanol, and n-hexane. The molar volume of water for commercial, brackish-water membranes was approximately equal to that of bulk water, while high-flux brackish-water and NF membranes exhibited significantly lower molar volumes, as compared to that of the bulk water. Surprisingly, slight changes in the molar volumes of water, ethanol, and n-hexane in organic NF membranes were observed. Significant changes in the physicochemical properties of water were identified in the Desal 5 membrane. These results indicate that the molar volume and compressibility enabled the pressure dependence of the RO and NF membranes. For all the membrane types, the resistance to flow, heat of vaporization, and diffusion coefficients controlled the magnitude of changes in flux due to pressure and temperature.

Phase-dependent forms of microscopy (such as phase contrast, interference, or polarization microscopy) have been used for many years; the amount of phase retardation produces images based mainly on index of refraction. We have developed a microscope that forms images that depend on small differences in extinction for different forms of incident polarized light. By modulating the polarization of light incident on the sample and digitally recording the difference in intensities of transmitted light, we obtain images which specifically reveal either ordered linear structures or chiral (right- or left-handed) structures. Linearly polarized light, incident alternately with two perpendicular directions of polarization, forms images of structures which have linear order or linear orientation. Right-handed and left-handed circularly polarized light incident alternately on a sample forms images of chiral structures. Structures with neither linear order nor chirality are essentially invisible. Thus, images based on linear dichroism, circular dichroism, and linear and circular differential scattering can be used to detect specific types of structures which may be difficult to observe by conventional methods. We have used such 'linear and circular differential imaging' to study the structure of the nucleolus (the site of RNA synthesis) in live primary spermatocytes of Drosophila when they are transcriptionally active or inactive. Some inactive nucleoli are bipartite, with two distinct structures visible by differential scattering of both linearly and circularly polarized light. The active nucleolus is a single domain; it is clearly distinguished from part of the Y chromosome, and it shows different internal structure with linearly and circularly polarized light. Thus, polarization-dependent images reveal structures which can be associated with the transcriptional activity of cells.

ABSTRACT A new method of obtaining images from biological specimens is presented. It is based on the fact that the molecular anisotropy of the object can be exploited by using polarized incident light. If a difference image of the object is obtained by using two orthogonal polarizations, the resulting image is found to be a bi-dimensional mapping ot the object's amsotropy. A prototype of a microscope capable of generating these differential images has been constructed and the results as applied to the study of sickled red blood cells are presented. Future applications and the potentialities of this novel technique are discussed.

Biofouling is a major reason for flux decline in the performance of membrane-based water and wastewater treatment plants. Initial biochemical characterization of biofilm formation potential and biofouling on two commercially available membrane surfaces from FilmTec Corporation were investigated without filtration in laboratory rotating disc reactor systems. These surfaces were polyamide aromatic thin-film reverse osmosis (RO) (BW30) and semi-aromatic nanofiltration (NF270) membranes. Membrane swatches were fixed on removable coupons and exposed to water with indigenous microorganisms supplemented with 1.5 mg l−1 organic carbon under continuous flow. After biofilms formed, the membrane swatches were removed for analyses. Staining and epifluorescence microscopy revealed more cells on the RO than on the NF surface. Based on image analyses of 5-μm thick cryo-sections, the accumulation of hydrated biofoulants on the RO and NF surfaces exceeded 0.74 and 0.64 μm day−1, respectively. As determined by contact angle the biofoulants increased the hydrophobicity up to 30° for RO and 4° for NF surfaces. The initial difference between virgin RO and NO hydrophobicities was ∼5°, which increased up to 25° after biofoulant formation. The initial roughness of RO and NF virgin surfaces (75.3 nm and 8.2 nm, respectively) increased to 48 nm and 39 nm after fouling. A wide range of changes of the chemical element mass percentages on membrane surfaces was observed with X-ray photoelectron spectroscopy. The initial chemical signature on the NF surface was better restored after cleaning than the RO membrane. All the data suggest that the semi-aromatic NF surface was more biofilm resistant than the aromatic RO surface. The morphology of the biofilm and the location of active and dead cell zones could be related to the membrane surface properties and general biofouling accumulation was associated with changes in the surface chemistry of the membranes, suggesting the validity of the combination of these novel approaches for initial assessment of membrane performance.

... California 94720 Joseph E. Katz Department of Instrument Science and Engineering, Lawrence Berkeley Laboratory, Berkeley, California 94720 Marcos F. Maestre ... 2. This photograph is a black and white copy of color coded images of fixed deoxygenated red blood cells from a ...

The distribution of oriented, polymerized sickle cell hemoglobin (hemoglobin S) in erythrocytes is visualized with a microscope that produces an image proportional to linear dichroism. Monochromatic light alternately polarized along two perpendicular directions is incident on the sample. The image is focused on a diode array, and the digital output is used to form two images. One is the usual image proportional to the average transmitted light intensity of the two incident polarizations of light; the other is a linear differential image proportional to the linear dichroism of the sample. This quantitative image can specifically reveal oriented hemoglobin molecules with a sensitivity of about 4000 oriented molecules per picture element of the image.

We have used differential polarization imaging microscopy to measure the amount and orientation of aligned sickle hemoglobin polymer in quickly deoxygenated sickle red blood cells. Images of the angular orientation of the aligned polymer at each point in the cell allowed for determination of the inclination of individual domains, providing detailed information regarding the polymerization and elongation of sickle hemoglobin polymers ex vivo. We found that the number of aligned polymer domains increased with increasing mean cell hemoglobin concentration. Sickle and holly leaf-shaped cells contained single or few domains of aligned polymer, while more compact cells such as irreversibly sickled cells contained many domains. A new class of cells was discovered by examination of images of the angular orientation of aligned polymer, which contained a single central nucleation site, with growth of polymer occurring outward in all directions in a spherulite-like domain.

Water is an increasingly scarce resource and in many regions people are turning to new sources such as seawater and wastewater. Various membrane technology improvements in the last decade have led to a significant cost reduction in reverse osmosis (RO). This has triggered ...

Water is an increasingly scarce resource and in many regions people are turning to new sources such as seawater and wastewater. Various membrane technology improvements in the last decade have led to a significant cost reduction in reverse osmosis (RO). This has triggered ...

Biofouling is a major reason for flux decline in the performance of membrane-based water and wastewater treatment plants. Initial biochemical characterization of biofilm formation potential and biofouling on two commercially available membrane surfaces from FilmTec Corporation were investigated without filtration in laboratory rotating disc reactor systems. These surfaces were polyamide aromatic thin-film reverse osmosis (RO) (BW30) and semi-aromatic nanofiltration (NF270) membranes. Membrane swatches were fixed on removable coupons and exposed to water with indigenous microorganisms supplemented with 1.5 mg l(-1) organic carbon under continuous flow. After biofilms formed, the membrane swatches were removed for analyses. Staining and epifluorescence microscopy revealed more cells on the RO than on the NF surface. Based on image analyses of 5-μm thick cryo-sections, the accumulation of hydrated biofoulants on the RO and NF surfaces exceeded 0.74 and 0.64 μm day(-1), respectively. As determined by contact angle the biofoulants increased the hydrophobicity up to 30° for RO and 4° for NF surfaces. The initial difference between virgin RO and NO hydrophobicities was ∼5°, which increased up to 25° after biofoulant formation. The initial roughness of RO and NF virgin surfaces (75.3 nm and 8.2 nm, respectively) increased to 48 nm and 39 nm after fouling. A wide range of changes of the chemical element mass percentages on membrane surfaces was observed with X-ray photoelectron spectroscopy. The initial chemical signature on the NF surface was better restored after cleaning than the RO membrane. All the data suggest that the semi-aromatic NF surface was more biofilm resistant than the aromatic RO surface. The morphology of the biofilm and the location of active and dead cell zones could be related to the membrane surface properties and general biofouling accumulation was associated with changes in the surface chemistry of the membranes, suggesting the validity of the combination of these novel approaches for initial assessment of membrane performance.

DNA-protein condensates that give positive and negative psi-type circular dichroism (CD) spectra (psi condensates) bind intercalative and nonintercalative dyes. CD depends both on circular differential scattering and on circular differential absorption; scattering-corrected CD measurements are approximations to circular differential absorption. The circular differential scattering and scattering-corrected CD patterns observed in the DNA absorption band of psi condensates are mimicked in the induced CD band of intercalators bound to psi condensates. The induced scattering-corrected CD and circular differential scattering patterns of the groove-binding dye Hoechst 33342 bound to psi condensates are the inverse of the patterns seen with intercalative dyes, whereas the groove-binding dye manganese(III) meso-tetrakis(4-N-methylpyridyl)porphine [MnIIITMpyP-4] shows no significant induced CD patterns. The large circular differential scattering and scattering-corrected CD bands are interpreted as resulting from long-range chiral packing, rather than near-neighbor short-range interactions. Dyes intercalated into the DNA of the psi condensates have the same type of long-range chiral packing as the DNA bases. Therefore, the psi-type CD spectra seen in the UV spectra originating from the long-range packing of the DNA bases are also observed in the visible spectra when dyes are intercalated in the DNA of the psi condensates. Our interpretation comes from the observation that the induced circular differential scattering and circular differential absorption of the dye bound to the psi condensates depend only upon the sign of the circular differential absorption and the pattern of the circular differential scattering of the psi condensates without bound dye.(ABSTRACT TRUNCATED AT 250 WORDS)