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Sample records for absolute molecular weight

  1. Performance on absolute scattering intensity calibration and protein molecular weight determination at BL16B1, a dedicated SAXS beamline at SSRF.

    Science.gov (United States)

    Zeng, Jianrong; Bian, Fenggang; Wang, Jie; Li, Xiuhong; Wang, Yuzhu; Tian, Feng; Zhou, Ping

    2017-03-01

    The optical system and end-station of bending-magnet beamline BL16B1, dedicated to small-angle X-ray scattering (SAXS) at the Shanghai Synchrotron Radiation Facility, is described. Constructed in 2009 and upgraded in 2013, this beamline has been open to users since May 2009 and supports methodologies including SAXS, wide-angle X-ray scattering (WAXS), simultaneous SAXS/WAXS, grazing-incidence small-angle X-ray scattering (GISAXS) and anomalous small-angle X-ray scattering (ASAXS). Considering that an increasing necessity for absolute calibration of SAXS intensity has been recognized in in-depth investigations, SAXS intensity is re-stated according to the extent of data processing, and the absolute intensity is suggested to be a unified presentation of SAXS data in this article. Theory with a practical procedure for absolute intensity calibration is established based on BL16B1, using glass carbon and water as primary and secondary standards, respectively. The calibration procedure can be completed in minutes and shows good reliability under different conditions. An empirical line of scale factor estimation is also established for any specific SAXS setup at the beamline. Beamline performance on molecular weight (MW) determination is provided as a straightforward application and verification of the absolute intensity calibration. Results show good accuracy with a deviation of less than 10% compared with the known value, which is also the best attainable accuracy in recent studies using SAXS to measure protein MW. Fast MW measurement following the demonstrated method also enables an instant check or pre-diagnosis of the SAXS performance to improve the data acquisition.

  2. Incorrect Weighting of Absolute Performance in Self-Assessment

    Science.gov (United States)

    Jeffrey, Scott A.; Cozzarin, Brian

    Students spend much of their life in an attempt to assess their aptitude for numerous tasks. For example, they expend a great deal of effort to determine their academic standing given a distribution of grades. This research finds that students use their absolute performance, or percentage correct as a yardstick for their self-assessment, even when relative standing is much more informative. An experiment shows that this reliance on absolute performance for self-evaluation causes a misallocation of time and financial resources. Reasons for this inappropriate responsiveness to absolute performance are explored.

  3. Correlates of absolute and excessive weight gain during pregnancy

    NARCIS (Netherlands)

    Althuizen, Ellen; van Poppel, Mireille Nm; Seidell, Jacob C; van Mechelen, Willem

    2009-01-01

    OBJECTIVE: Factors associated with weight gain during pregnancy that may be linked to maternal overweight and obesity were examined. METHODS: In this observational study, 144 women reported on demographics, (prepregnancy) body weight, and lifestyles in self-reported questionnaires at 30 weeks

  4. Effect of molecular weight on polyphenylquinoxaline properties

    Science.gov (United States)

    Jensen, Brian J.

    1991-01-01

    A series of polyphenyl quinoxalines with different molecular weight and end-groups were prepared by varying monomer stoichiometry. Thus, 4,4'-oxydibenzil and 3,3'-diaminobenzidine were reacted in a 50/50 mixture of m-cresol and xylenes. Reaction concentration, temperature, and stir rate were studied and found to have an effect on polymer properties. Number and weight average molecular weights were determined and correlated well with viscosity data. Glass transition temperatures were determined and found to vary with molecular weight and end-groups. Mechanical properties of films from polymers with different molecular weights were essentially identical at room temperature but showed significant differences at 232 C. Diamine terminated polymers were found to be much less thermooxidatively stable than benzil terminated polymers when aged at 316 C even though dynamic thermogravimetric analysis revealed only slight differences. Lower molecular weight polymers exhibited better processability than higher molecular weight polymers.

  5. Production of high molecular weight polylactic acid

    Science.gov (United States)

    Bonsignore, P.V.

    1995-11-28

    A degradable high molecular weight poly(lactic acid) is described. The poly(lactic acid) has a terminal end group of one of carboxyl or hydroxyl groups with low molecular weight poly(lactic acid) units coupled with linking agents of di-isocyanates, bis-epoxides, bis-oxazolines and bis-ortho esters. The resulting high molecular weight poly(lactic acid) can be used for applications taking advantage of the improved physical properties.

  6. Solvothermal synthesis of high molecular weight dithienogermole ...

    Indian Academy of Sciences (India)

    cation of the resulting organic products by the Soxhlet extraction gave the target polymers with high molecular weight and low polydispersity index (PDI). The higher molecular weight of pDTG-PH may be ascribed to high solubility of the polymers than those of pDTG-BTA. The long branched alkyl chain in acceptor part may.

  7. Solvothermal synthesis of high molecular weight dithienogermole ...

    Indian Academy of Sciences (India)

    dithiadiazole alternate polymers were synthesized by the solvothermal method. Optical properties and molecular weight were investigated by UV–Vis absorption spectroscopy and Gel Permeation Chromatography. Compared with the results achieved ...

  8. High Molecular Weight Melanoidins from Coffee Brew

    NARCIS (Netherlands)

    Bekedam, E.K.; Schols, H.A.; Boekel, van T.; Smit, G.

    2006-01-01

    The composition of high molecular weight (HMw) coffee melanoidin populations, obtained after ethanol precipitation, was studied. The specific extinction coefficient (Kmix) at 280, 325, 405 nm, sugar composition, phenolic group content, nitrogen content, amino acid composition, and non-protein

  9. Molecular weight characterisation of synthetic polymers

    CERN Document Server

    Holding, Steve R

    1995-01-01

    The report comprises a state-of-the-art overview of the subject of molecular weight characterisation, supported by an extensive, indexed bibliography. The bibliography contains over 400 references and abstracts, compiled from the Polymer Library.

  10. Molecular weight scaling in critical polymer mixtures

    DEFF Research Database (Denmark)

    Gehlsen, M.D.; Rosedale, J.R.; Bates, F.S.

    1992-01-01

    , DELTA-X(D), and molecular weight by small-angle neutron scattering. The critical point for demixing was determined to scale as chi(eff,c) is similar to N(-delta) with delta = 1.01 +/- 0.05, where N is the degree of polymerization. This result confirms the mean-field prediction of Flory and Huggins....

  11. Sintering of ultra high molecular weight polyethylene

    Indian Academy of Sciences (India)

    Abstract. Ultra high molecular weight polyethylene (UHMWPE) is a high performance polymer having low coefficient of friction, good abrasion resistance, good chemical ... In this study, we report our results on compaction and sintering behaviour of two grades of UHMWPE with reference to the powder morphology, sintering ...

  12. Low Molecular Weight Melanoidins in Coffee Brew

    NARCIS (Netherlands)

    Bekedam, E.K.; Roos, E.; Schols, H.A.; Boekel, van M.A.J.S.; Smit, G.

    2008-01-01

    Analysis of low molecular weight (LMw) coffee brew melanoidins is challenging due to the presence of many non-melanoidin components that complicate analysis. This study focused on the isolation of LMw coffee brew melanoidins by separation of melanoidins from non-melanoidin components that are

  13. Influence of Hydroxypropyl Methylcellulose Molecular Weight Grade ...

    African Journals Online (AJOL)

    Kinetic data based on the release exponent, n, in Peppas model, showed that n values were between 0.14 and 0.55, indicating that drug release from HPMC matrices was predominantly by diffusion. Conclusion: This study demonstrates that the molecular weight (MW) of HPMC does affect the water uptake and erosion as ...

  14. a Chiral Tagging Strategy for Determining Absolute Configuration and Enantiomeric Excess by Molecular Rotational Spectroscopy

    Science.gov (United States)

    Evangelisti, Luca; Caminati, Walther; Patterson, David; Thomas, Javix; Xu, Yunjie; West, Channing; Pate, Brooks

    2017-06-01

    The introduction of three wave mixing rotational spectroscopy by Patterson, Schnell, and Doyle [1,2] has expanded applications of molecular rotational spectroscopy into the field of chiral analysis. Chiral analysis of a molecule is the quantitative measurement of the relative abundances of all stereoisomers of the molecule and these include both diastereomers (with distinct molecular rotational spectra) and enantiomers (with equivalent molecular rotational spectra). This work adapts a common strategy in chiral analysis of enantiomers to molecular rotational spectroscopy. A "chiral tag" is attached to the molecule of interest by making a weakly bound complex in a pulsed jet expansion. When this tag molecule is enantiopure, it will create diastereomeric complexes with the two enantiomers of the molecule being analyzed and these can be differentiated by molecule rotational spectroscopy. Identifying the structure of this complex, with knowledge of the absolute configuration of the tag, establishes the absolute configuration of the molecule of interest. Furthermore, the diastereomer complex spectra can be used to determine the enantiomeric excess of the sample. The ability to perform chiral analysis will be illustrated by a study of solketal using propylene oxide as the tag. The possibility of using current methods of quantum chemistry to assign a specific structure to the chiral tag complex will be discussed. Finally, chiral tag rotational spectroscopy offers a "gold standard" method for determining the absolute configuration of the molecule through determination of the substitution structure of the complex. When this measurement is possible, rotational spectroscopy can deliver a quantitative three dimensional structure of the molecule with correct stereochemistry as the analysis output. [1] David Patterson, Melanie Schnell, John M. Doyle, Nature 497, 475 (2013). [2] David Patterson, John M. Doyle, Phys. Rev. Lett. 111, 023008 (2013).

  15. Polymer Molecular Weight Analysis by [Superscript 1]H NMR Spectroscopy

    Science.gov (United States)

    Izunobi, Josephat U.; Higginbotham, Clement L.

    2011-01-01

    The measurement and analysis of molecular weight and molecular weight distribution remain matters of fundamental importance for the characterization and physical properties of polymers. Gel permeation chromatography (GPC) is the most routinely used method for the molecular weight determination of polymers whereas matrix-assisted laser…

  16. Low molecular weight melanoidins in coffee brew.

    Science.gov (United States)

    Bekedam, E Koen; Roos, Ellen; Schols, Henk A; Van Boekel, Martinus A J S; Smit, Gerrit

    2008-06-11

    Analysis of low molecular weight (LMw) coffee brew melanoidins is challenging due to the presence of many non-melanoidin components that complicate analysis. This study focused on the isolation of LMw coffee brew melanoidins by separation of melanoidins from non-melanoidin components that are present in LMw coffee brew material. LMw coffee fractions differing in polarity were obtained by reversed-phase solid phase extraction and their melanoidin, sugar, nitrogen, caffeine, trigonelline, 5-caffeoylquinic acid, quinic acid, caffeic acid, and phenolic groups contents were determined. The sugar composition, the charge properties, and the absorbance at various wavelengths were investigated as well. The majority of the LMw melanoidins were found to have an apolar character, whereas most non-melanoidins have a polar character. The three isolated melanoidin-rich fractions represented 56% of the LMw coffee melanoidins and were free from non-melanoidin components. Spectroscopic analysis revealed that the melanoidins isolated showed similar features as high molecular weight coffee melanoidins. All three melanoidin fractions contained approximately 3% nitrogen, indicating the presence of incorporated amino acids or proteins. Surprisingly, glucose was the main sugar present in these melanoidins, and it was reasoned that sucrose is the most likely source for this glucose within the melanoidin structure. It was also found that LMw melanoidins exposed a negative charge, and this negative charge was inversely proportional to the apolar character of the melanoidins. Phenolic group levels as high as 47% were found, which could be explained by the incorporation of chlorogenic acids in these melanoidins.

  17. The fruitful introduction of chirality and control of absolute configurations in molecular magnets.

    Science.gov (United States)

    Train, Cyrille; Gruselle, Michel; Verdaguer, Michel

    2011-06-01

    In this critical review, it is shown how the introduction of chirality and the control of the absolute configurations of chiral elements in molecular magnets allow obtaining enantiopure chiral magnets (ECM), an archetype of multifunctional materials. This task has been recognised as a major challenge for both chemists and physicists of molecular magnetism. To reach this goal, the former have combined the rational approaches towards molecular-based magnets and of enantiopure metal-organic frameworks. They have used enantiopure stable radicals, ligands from the chiral pool, enantiopure coligands associated with achiral connectors or enantioselective self-assembly to successfully reach their synthetic targets. They were motivated by the will to obtain suitable systems for the experimental demonstration of the influence of enantiomeric purity on the physico-chemical properties. This influence can be found in the magnetic properties themselves but, most interestingly, in the coexistence and interaction between the properties arising from controlled non-centrosymmetry. Thus the combination of natural circular dichroism, second harmonic generation or ferroelectricity with long-range magnetic ordering can give birth to new properties like magneto-chiral dichroism, magnetisation induced second harmonic generation or multiferroicity. The two former synergetic effects have already been demonstrated in enantiopure chiral magnets. The third one remains a challenging target that can be reached by adapting strategies developed towards enantiopure molecular ferroelectrics (119 references).

  18. Menstrual cycle loss and resumption among patients with anorexia nervosa spectrum eating disorders: Is relative or absolute weight more influential?

    Science.gov (United States)

    Berner, Laura A; Feig, Emily H; Witt, Ashley A; Lowe, Michael R

    2017-04-01

    Prior research suggests that both body mass index (BMI) and weight suppression (highest past weight minus current weight; WS) are important in determining adult anorexia nervosa (AN) severity. We examined associations between amenorrhea and WS, DSM-5 BMI severity category, and highest premorbid BMI among patients with AN. Participants (N = 69) were adult female AN-spectrum patients at two residential treatment facilities. At admission, height, and weight were measured, and participants completed questionnaires assessing menstrual status and weight history. Greater WS, adjusted for BMI, was associated with menstrual function at admission. First amenorrhea onset occurred at a normal BMI for 38.5% of participants. Premorbid highest BMI positively correlated with BMI at amenorrhea onset, and higher BMI at amenorrhea onset was associated with higher BMI at menses resumption. These findings add to the literature indicating that relative and absolute weight status are dual indicators of illness severity in AN, and preliminarily suggest that a large proportion of adults who present for treatment initially may have shown symptoms of starvation at a normal BMI. Results underscore the need to focus on weight loss in early detection efforts and may inform target weight setting in the treatment of AN. © 2017 Wiley Periodicals, Inc.

  19. Molecular Formula and Molecular Weight - NBDC NikkajiRDF | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available List Contact us NBDC NikkajiRDF Molecular Formula and Molecular Weight Data detail Data name Molecular Formula and Molecular...cular Formula and Molecular Weight - NBDC NikkajiRDF | LSDB Archive ... ...329 triples - About This Database Database Description Download License Update History of This Database Site Policy | Contact Us Mole

  20. Absolute and relative densities of fast-food versus other restaurants in relation to weight status: Does restaurant mix matter?

    Science.gov (United States)

    Polsky, Jane Y; Moineddin, Rahim; Dunn, James R; Glazier, Richard H; Booth, Gillian L

    2016-01-01

    Given the continuing epidemic of obesity, policymakers are increasingly looking for levers within the local retail food environment as a means of promoting healthy weights. To examine the independent and joint associations of absolute and relative densities of restaurants near home with weight status in a large, urban, population-based sample of adults. We studied 10,199 adults living in one of four cities in southern Ontario, Canada, who participated in the Canadian Community Health Survey (cycles 2005, 2007/08, 2009/10). Multivariate models assessed the association of weight status (obesity and body mass index) with absolute densities (numbers) of fast-food, full-service and other restaurants, and the relative density (proportion) of fast-food restaurants (FFR) relative to all restaurants within ~10-minute walk of residential areas. Higher numbers of restaurants of any type were inversely related to excess weight, even in models adjusting for a range of individual covariates and area deprivation. However, these associations were no longer significant after accounting for higher walkability of areas with high volumes of restaurants. In contrast, there was a direct relationship between the proportion of FFR relative to all restaurants and excess weight, particularly in areas with high volumes of FFR (e.g., odds ratio for obesity=2.55 in areas with 5+ FFR, 95% confidence interval: 1.55-4.17, across the interquartile range). Policies aiming to promote healthy weights that target the volume of certain retail food outlets in residential settings may be more effective if they also consider the relative share of outlets serving more and less healthful foods. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Molecular weights and molecular weight distributions of irradiated cellulose fibers by gel permeation chromatography

    International Nuclear Information System (INIS)

    Kusama, Y.; Kageyama, E.; Shimada, M.; Nakamura, Y.

    1976-01-01

    Radiation degradation of cellulose fibers was investigated by gel permeation chromatography (GPC). Scoured cotton of Mexican variety (cellulose I), Polynosic rayon (cellulose II), and their microcrystalline celluloses obtained by hydrolysis of the original fibers were irradiated by Co-60 γ-rays under vacuum or humid conditions. The irradiated samples were then nitrated under nondegradative conditions. The molecular weights and molecular weight distributions were measured by GPC using tetrahydrofuran as solvent. The relationship between molecular weight and elution count was obtained with cellulose trinitrate standards fractionated by preparative GPC. The degree of polymerization of the fibers decreased with increasing irradiation dose, but their microcrystalline celluloses were only slightly degraded by irradiation, especially in microcrystalline cellulose from cellulose I. Degradation of the fibers irradiated under humid conditions was less than that irradiated under vacuum. It was found that the G-values for main-chain scission for the irradiated cellulose I, cellulose II, microcrystalline cellulose I, and microcrystalline cellulose II were 2.8, 2.9, less than 1, and 2.9, respectively, but the G-value for main-chain scission for the irradiated cellulose II was increased to 11.2 at irradiation doses above 3 Mrad. Consequently, it is inferred that cellulose molecules in the amorphous regions are degraded more readily, and the well-aligned molecules in crystalline regions are not as easily degraded by irradiation

  2. The effect of monomer molecular weight on grafting reaction

    International Nuclear Information System (INIS)

    Wu Minghong; Ding Zhongli; Ma Zueteh

    1995-01-01

    In this paper, some condensed ethylene glycol acrylate monomers with different molecular weight being grafted to the PE film by means of pre-irradiation is reported. The effect of molecular weight of monomer on grafting reaction and the hydrophilicity of grafting sample have been discussed. The experimental results show: molar degrees of grafting decreased non-linearly with the increasement of molecular weight of monomer, the grafting reaction of polymer is greater effected by the swelling degree of PE film, the greater the swelling degree of grafting material, the higher the grating degree grafting is, the initial rate of grafting reaction decreased with the increasement of molecular weight of monomer. (author)

  3. Hydrodynamic caracterization and molecular weight stimation of ultrasonically sheared DNA

    International Nuclear Information System (INIS)

    Garces, F.; Casal, J.I.; Garcia, A.

    1981-01-01

    The sedimentation coefficients and intrinsec viscosities of ultrasonically sheared calf thymus DNA have been determined. The molecular weight stimation according to this parameters have been compared with the ones obtained from the electrophoretic migration rates based on the calibration proposed using the known molecular weight restriction fragments of lambds-DNA. (author) [es

  4. Anticoagulant effect of low molecular weight heparin on central ...

    African Journals Online (AJOL)

    Purpose: To analyse the effect of low molecular weight heparin on venous catheters in haemodialysis patients. Methods: This study included 140 eligible patients who were randomly and evenly divided into two groups, viz, a study group that received low molecular weight heparin and a control group that received ...

  5. Extraction of low molecular weight RNA from Citrus trifolita tissues ...

    African Journals Online (AJOL)

    Jane

    2010-12-20

    Dec 20, 2010 ... reaction (RT-PCR) and Northern blotting. Key words: Citrus, low molecular weight RNA, trizol reagent, 4 M LiCl, microRNAs. INTRODUCTION. Low molecular weight RNA (LMW RNA) consists of several components with microRNAs (miRNAs) being among the important ones. miRNAs are endogenous 19-.

  6. Hydrodynamic characterization and molecular weight estimation of ultrasonically sheared DNA

    International Nuclear Information System (INIS)

    Casal, J. I.; Garces, F.; Garcia-Sacristan, A.

    1981-01-01

    The sedimentation coefficients and intrinsic viscosities of ultrasonically sheared calf thymus DNA have been determined. The molecular weight estimation according to this parameters have been compared with the ones obtained from the electrophoretic migration rates based on the calibration proposed using the known molecular weight restriction fragments of X-ENA. (Author) 35 refs

  7. Determination of the absolute binding free energies of HIV-1 protease inhibitors using non-equilibrium molecular dynamics simulations

    Science.gov (United States)

    Ngo, Son Tung; Nguyen, Minh Tung; Nguyen, Minh Tho

    2017-05-01

    The absolute binding free energy of an inhibitor to HIV-1 Protease (PR) was determined throughout evaluation of the non-bonded interaction energy difference between the two bound and unbound states of the inhibitor and surrounding molecules by the fast pulling of ligand (FPL) process using non-equilibrium molecular dynamics (NEMD) simulations. The calculated free energy difference terms help clarifying the nature of the binding. Theoretical binding affinities are in good correlation with experimental data, with R = 0.89. The paradigm used is able to rank two inhibitors having the maximum difference of ∼1.5 kcal/mol in absolute binding free energies.

  8. Characterization of Methane Excess and Absolute Adsorption in Various Clay Nanopores from Molecular Simulation.

    Science.gov (United States)

    Tian, Yuanyuan; Yan, Changhui; Jin, Zhehui

    2017-09-20

    In this work, we use grand canonical Monte Carlo (GCMC) simulation to study methane adsorption in various clay nanopores and analyze different approaches to characterize the absolute adsorption. As an important constituent of shale, clay minerals can have significant amount of nanopores, which greatly contribute to the gas-in-place in shale. In previous works, absolute adsorption is often calculated from the excess adsorption and bulk liquid phase density of absorbate. We find that methane adsorbed phase density keeps increasing with pressure up to 80 MPa. Even with updated adsorbed phase density from GCMC, there is a significant error in absolute adsorption calculation. Thus, we propose to use the excess adsorption and adsorbed phase volume to calculate absolute adsorption and reduce the discrepancy to less than 3% at high pressure conditions. We also find that the supercritical Dubinin-Radushkevich (SDR) fitting method which is commonly used in experiments to convert the excess adsorption to absolute adsorption may not have a solid physical foundation for methane adsorption. The methane excess and absolute adsorptions per specific surface area are similar for different clay minerals in line with previous experimental data. In mesopores, the excess and absolute adsorptions per specific surface area become insensitive to pore size. Our work should provide important fundamental understandings and insights into accurate estimation of gas-in-place in shale reservoirs.

  9. Influence of Hydroxypropyl Methylcellulose Molecular Weight Grade ...

    African Journals Online (AJOL)

    Erah

    2011-01-12

    Jan 12, 2011 ... weight grades (K4M and K15M) on drug release from diclofenac sodium matrix tablets. Methods: Tablets containing diclofenac sodium were prepared by direct compression method at various drug/HPMC ratios and evaluated in vitro for their water uptake, erosion and dissolution characteristics.

  10. Solvothermal synthesis of high molecular weight dithienogermole ...

    Indian Academy of Sciences (India)

    The onset oxidation potentials of the films were very similar to those reported for pDTS-PH23 and. pDTG-BTA.21,24. 3.4 Thermal stability of polymers. Thermal stability of the polymers was investigated by thermogravimetric analysis (TGA) in nitrogen and 5% weight loss temperatures (T 5 d ) were noted as listed in table 1.

  11. Isolation, characterization and Molecular weight Determination of ...

    African Journals Online (AJOL)

    Salwee

    2013-07-10

    Jul 10, 2013 ... chromatography on DEAE-Sepharose. SDS-PAGE revealed molecular mass of 87 kDa. .... activity protein profile on the SDS-PAGE prior to anion exchange chromatography. The anion exchange ... of non-ionic detergent, Triton-X100, at a final concentration of 0.1% and also 0.2 and 5% ethanol and after 3 ...

  12. High Molecular Weight Polymers in the New Chemicals Program

    Science.gov (United States)

    There are three categories or types of High Molecular Weight (HMW, 10,000 daltons) polymers typically reviewed by the New Chemicals Program: Soluble, insoluble, and water absorbing. Each of the three types are treated differently.

  13. Protein molecular weight computation from sedimentation velocity data

    NARCIS (Netherlands)

    Grievink, J; Houterman, R.T.B.; de Groot, K.

    1974-01-01

    In ultracentrifugation, the concentration gradient of mono-disperse samples obtained by sedimentation velocity experiments is described by Gehatia's equation which holds several parameters including the sedimentation and diffusion constants. Once these two constants are known, the molecular weight

  14. Low molecular weight salts combined with fluorinated solvents for electrolytes

    Science.gov (United States)

    Tikhonov, Konstantin; Yip, Ka Ki; Lin, Tzu-Yuan; Lei, Norman; Guerrero-Zavala, Guillermo; Kwong, Kristie W.

    2015-11-10

    Provided are electrochemical cells and electrolytes used to build such cells. An electrolyte includes at least one salt having a molecular weight less than about 250. Such salts allow forming electrolytes with higher salt concentrations and ensure high conductivity and ion transport in these electrolytes. The low molecular weight salt may have a concentration of at least about 0.5M and may be combined with one or more other salts, such as linear and cyclic imide salts and/or methide salts. The concentration of these additional salts may be less than that of the low molecular weight salt, in some embodiments, twice less. The additional salts may have a molecular weight greater than about 250. The electrolyte may also include one or more fluorinated solvents and may be capable of maintaining single phase solutions at between about -30.degree. C. to about 80.degree. C.

  15. Influence of Polymer Molecular Weight on Drug-Polymer Solubility

    DEFF Research Database (Denmark)

    Knopp, Matthias Manne; Olesen, Niels Erik; Holm, Per

    2015-01-01

    In this study, the influence of polymer molecular weight on drug-polymer solubility was investigated using binary systems containing indomethacin (IMC) and polyvinylpyrrolidone (PVP) of different molecular weights. The experimental solubility in PVP, measured using a differential scanning...... calorimetry annealing method, was compared with the solubility calculated from the solubility of the drug in the liquid analogue N-vinylpyrrolidone (NVP). The experimental solubility of IMC in the low-molecular-weight PVP K12 was not significantly different from that in the higher molecular weight PVPs (K25......, K30, and K90). The calculated solubilities derived from the solubility in NVP (0.31-0.32 g/g) were found to be lower than those experimentally determined in PVP (0.38-0.40 g/g). Nevertheless, the similarity between the values indicates that the analogue solubility can provide valuable indications...

  16. Liquid hydrocarbon fuels containing high molecular weight Mannich bases

    Energy Technology Data Exchange (ETDEWEB)

    Udelhofen, J.H.; Watson, R.W.

    1980-11-04

    Reaction products obtained from the Mannich condensation of high molecular weight alkyl-substituted hydroxy aromatic compounds, amines and aldehydes provide improved detergency in liquid hydrocarbon fuels. Optionally, a non-volatile hydrocarbon carrier fluid may be included.

  17. Isolation, Characterization and Molecular weight determination of ...

    African Journals Online (AJOL)

    Enzyme purification to homogeneity was carried out by anion exchange chromatography on DEAE-Sepharose. SDS-PAGE revealed molecular mass of 87 kDa. Maximal activity of the enzymes was observed at 50°C at pH 4 and was stimulated by Ca2+, Co2+, Mg2+ (test at 10 Mm each) and inhibited by Fe2+. Ethanol at an ...

  18. The effect of different molecular weight hyaluronan on macrophage physiology.

    Science.gov (United States)

    Krejcova, Daniela; Pekarova, Michaela; Safrankova, Barbora; Kubala, Lukas

    2009-01-01

    Hyaluronan, a linear glycosaminoglycan, is an abundant component of extracellular matrix. In its native form, the high-molar-mass hyaluronan polymers have an array of structural and regulatory, mainly anti-inflammatory and anti-angiogenic, functions. In contradiction, the biological effects of fragmented low molecular weight hyaluronan are suggested to be pro-angiogenic and pro-inflammatory. The effects of highly purified pharmacological grade hyaluronan of defined molecular weights 11, 52, 87, 250 and 970 kilodaltons were tested on mouse macrophage cell lines RAW 264.7 and MHS. The surface expression of CD44 and Toll-like receptor 2, surface receptors for hyaluronan, was determined by flow cytometry. Activation of macrophages was determined based on nitric oxide and tumour necrosis factor alpha production, inducible nitric oxide synthase expression, and the activation of the nuclear factor kappa B transcriptional factor. Both macrophage cell lines expressed CD44 and Toll-like receptor 2, which were significantly increased by the pre-treatment of macrophages with bacterial lipopolysaccharide. Hyaluronan of any molecular weight did not activate production of nitric oxide or tumour necrosis factor alpha in any mouse macrophage cell lines. Correspondingly, hyaluronan of any tested molecular weight did not stimulate nuclear factor kappa B activation. Similarly, hyaluronan of any molecular weight neither exerted stimulatory nor inhibitory effects on macrophages pre-treated by lipopolysaccharide. Interestingly, the data does not support the current view of low molecular weight hyaluronan as a pro-inflammatory mediator for macrophages. Further studies are necessary to clarify the effects of different molecular weight hyaluronan on phagocytes.

  19. Virus Infection Triggers MAVS Polymers of Distinct Molecular Weight

    Directory of Open Access Journals (Sweden)

    Natalia Zamorano Cuervo

    2018-01-01

    Full Text Available The mitochondrial antiviral signaling (MAVS adaptor protein is a central signaling hub required for cells to mount an antiviral response following virus sensing by retinoic acid-inducible gene I (RIG-I-like receptors. MAVS localizes in the membrane of mitochondria and peroxisomes and in mitochondrial-associated endoplasmic reticulum membranes. Structural and functional studies have revealed that MAVS activity relies on the formation of functional high molecular weight prion-like aggregates. The formation of protein aggregates typically relies on a dynamic transition between oligomerization and aggregation states. The existence of intermediate state(s of MAVS polymers, other than aggregates, has not yet been documented. Here, we used a combination of non-reducing SDS-PAGE and semi-denaturing detergent agarose gel electrophoresis (SDD-AGE to resolve whole cell extract preparations to distinguish MAVS polymerization states. While SDD-AGE analysis of whole cell extracts revealed the formation of previously described high molecular weight prion-like aggregates upon constitutively active RIG-I ectopic expression and virus infection, non-reducing SDS-PAGE allowed us to demonstrate the induction of lower molecular weight oligomers. Cleavage of MAVS using the NS3/4A protease revealed that anchoring to intracellular membranes is required for the appropriate polymerization into active high molecular weight aggregates. Altogether, our data suggest that RIG-I-dependent MAVS activation involves the coexistence of MAVS polymers with distinct molecular weights.

  20. Influence of Molecular Weight and Degree of Deacetylation of Low Molecular Weight Chitosan on the Bioactivity of Oral Insulin Preparations

    Directory of Open Access Journals (Sweden)

    Nidal A. Qinna

    2015-03-01

    Full Text Available The objective of the present study was to prepare and characterize low molecular weight chitosan (LMWC with different molecular weight and degrees of deacetylation (DDA and to optimize their use in oral insulin nano delivery systems. Water in oil nanosized systems containing LMWC-insulin polyelectrolyte complexes were constructed and their ability to reduce blood glucose was assessed in vivo on diabetic rats. Upon acid depolymerization and testing by viscosity method, three molecular weights of LMWC namely, 1.3, 13 and 18 kDa were obtained. As for the DDA, three LMWCs of 55%, 80% and 100% DDA were prepared and characterized by spectroscopic methods for each molecular weight. The obtained LMWCs showed different morphological and in silico patterns. Following complexation of LMWCs with insulin, different aggregation sizes were obtained. Moreover, the in vivo tested formulations showed different activities of blood glucose reduction. The highest glucose reduction was achieved with 1.3 kDa LMWC of 55% DDA. The current study emphasizes the importance of optimizing the molecular weight along with the DDA of the incorporated LMWC in oral insulin delivery preparations in order to ensure the highest performance of such delivery systems.

  1. Influence of Molecular Weight and Degree of Deacetylation of Low Molecular Weight Chitosan on the Bioactivity of Oral Insulin Preparations

    Science.gov (United States)

    Qinna, Nidal A.; Karwi, Qutuba G.; Al-Jbour, Nawzat; Al-Remawi, Mayyas A.; Alhussainy, Tawfiq M.; Al-So’ud, Khaldoun A.; Al Omari, Mahmoud M. H.; Badwan, Adnan A.

    2015-01-01

    The objective of the present study was to prepare and characterize low molecular weight chitosan (LMWC) with different molecular weight and degrees of deacetylation (DDA) and to optimize their use in oral insulin nano delivery systems. Water in oil nanosized systems containing LMWC-insulin polyelectrolyte complexes were constructed and their ability to reduce blood glucose was assessed in vivo on diabetic rats. Upon acid depolymerization and testing by viscosity method, three molecular weights of LMWC namely, 1.3, 13 and 18 kDa were obtained. As for the DDA, three LMWCs of 55%, 80% and 100% DDA were prepared and characterized by spectroscopic methods for each molecular weight. The obtained LMWCs showed different morphological and in silico patterns. Following complexation of LMWCs with insulin, different aggregation sizes were obtained. Moreover, the in vivo tested formulations showed different activities of blood glucose reduction. The highest glucose reduction was achieved with 1.3 kDa LMWC of 55% DDA. The current study emphasizes the importance of optimizing the molecular weight along with the DDA of the incorporated LMWC in oral insulin delivery preparations in order to ensure the highest performance of such delivery systems. PMID:25826718

  2. Development of radiation-resisting high molecular-weight materials

    International Nuclear Information System (INIS)

    Nakagawa, Tsutomu

    1976-01-01

    The excellent radiation-resisting polyvinyl chloride developed at the opportunity of the research on the relationships between the protection of living body and the polymer-technological protection from radiation is reviewed. The report is divided into four main parts, namely 1) the change in the molecular arrangement of market-available, high molecular-weight materials by gamma-ray irradiation, 2) the protection of high molecular-weight materials from radiation, 3) the relationships between the biological radiation-protective substances and the change to radiation-resisting property of synthesized high molecular-weight substances, and 4) the development of the radiation-resisting high molecular-weight materials as metal-collecting agents. Attention is paid to the polyvinyl chloride having N-methyl-dithio-carbamate radical (PMD), synthesized by the author et. al., that has excellent radiation-resisting property. PMD has some possibility to form thiol- and amino-radicals necessary to protect living things from radiation. It is believed that the protection effects of N-methyl-dithio-carbamate radical are caused by the relatively stable S radical produced by the energy transfer. PMD film is suitable for the irradiation of foods, because it hardly changes the permeability of oxygen and carbon dioxide. PMD produces mercaptide or chelate. A new metal-collecting agent (PSDC) having reactivity with the metallic ions with radiation-resisting property was developed, which is derived from polyvinyl chloride and sodium N-methyl-N-carboxy-methyl-dithio-carbamate. (Iwakiri, K.)

  3. Molecular weight dependence of exciton diffusion in poly(3-hexylthiophene)

    DEFF Research Database (Denmark)

    Masri, Zarifi; Ruseckas, Arvydas; Emelianova, Evguenia V.

    2013-01-01

    A joint experimental and theoretical study of singlet exciton diffusion in spin-coated poly(3-hexylthiophene) (P3HT) films and its dependence on molecular weight is presented. The results show that exciton diffusion is fast along the co-facial π–π aggregates of polymer chromophores and about 100...

  4. High molecular weight poly(4-trimethylsilyl-1-buten-3-yne)

    NARCIS (Netherlands)

    Mavinkurve, A; Visser, S; VandenBroek, W; TerBrugge, F; Pennings, AJ

    Selective polymerization of 4-trimethyl-1-buten-3-yne through the vinyl group, followed by cleavage of the protective trimethylsilyl group, was attempted as a possible route for obtaining high molecular weight poly(vinylacetylene). Anionic polymerization and thermally initiated radical

  5. Clinical effects of low-molecular-weight heparin combined with ...

    African Journals Online (AJOL)

    Purpose: To explore the clinical effects of low-molecular-weight heparin (LMWH) combined with ulinastatin (UTI) in children with acute pancreatitis. Methods: In total, 560 patients with severe acute pancreatitis treated at Binzhou People's Hospital, Shandong, China, from April 2012 to June 2014 were enrolled in this study.

  6. Characterization of low-molecular-weight glutenin subunit genes of ...

    Indian Academy of Sciences (India)

    2015-09-16

    Sep 16, 2015 ... species. Materials and methods. Plant materials. A total of 13 accessions from five species of Sitopsis were used for gene cloning (table 1 in electronic supplementary. Keywords. wheat; Aegilops; low-molecular-weight glutenin subunits; gene cloning; B genome; Triticum aestivum. Journal of Genetics, Vol.

  7. Preventive role of low-molecular-weight heparin in unexplained ...

    African Journals Online (AJOL)

    Background. Recurrent pregnancy loss (RPL) is a source of great distress for couples, and the search continues for an intervention to improve live birth rates in affected women. A daily injection of low-molecular-weight heparin (LMWH) is often prescribed to women with unexplained RPL, although evidence suggesting a ...

  8. Clinical effects of low-molecular-weight heparin combined with ...

    African Journals Online (AJOL)

    Purpose: To explore the clinical effects of low-molecular-weight heparin (LMWH) combined with ulinastatin (UTI) in children with acute pancreatitis. Methods: In total, 560 patients with severe acute pancreatitis treated at Binzhou People's Hospital,. Shandong, China, from April 2012 to June 2014 were enrolled in this study.

  9. Practical γ-Ray Level for Low Molecular Weight Chitosan

    International Nuclear Information System (INIS)

    Yoksan, Rangrong; Chirachanchai, Suwabun; Biramontri, Siriratana

    2003-06-01

    The present work proposes a practical level of γ-Ray to lower the molecular weigh of chitosan irradiated in solid state and water. The molecular weight reduction is up to 80% at γ-ray amount of 50 kGy. The same level of reduction can be achieved by only 20 kGy in the presence of initiator (K 2 S 2 O 8 or H 2 O 2 ). The structure is significantly changed in the case of chitosan-acetic acid solution or chitosan dispersed in water with 2% aq. K 2 S 2 O 8 solution

  10. Low molecular weight block copolymers as plasticizers for polystyrene

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Karsten; Nielsen, Charlotte Juel; Hvilsted, Søren

    2005-01-01

    Polystyrene-b-alkyl, polystyrene-b-polybutadiene-b-polystyrene, and polystyrene-b-poly(propylene glycol)monotridecyl ether were synthesized using macro initiators and atom transfer radical polymerization or by esterifications of homopolymers. The aim was a maximum molecular weight of 4 kg....../mol and minimum polystyrene content of 50 w/w%, which by us is predicted as the limits for solubility of polystyrene-b-alkyl in polystyrene. DSC showed polystyrene was plasticized, as seen by a reduction in glass transition temperature, by block copolymers consisting of a polystyrene block with molecular weight...... for polystyrene-b-polyisoprene-b-polystyrene (SIS) block copolymers. The end use properties of SIS plasticized with polystyrene-b-alkyl, measured as tensile strength, is higher than for SIS plasticized with dioctyl adipate. The polystyrene-b-polybutadiene-b-polystyrene and polystyrene-bpoly(propylene glycol...

  11. Prophylaxis of postoperative thromboembolism with low molecular weight heparins

    DEFF Research Database (Denmark)

    Jørgensen, L N; Wille-Jørgensen, P; Hauch, O

    1993-01-01

    To evaluate the thromboprophylactic use of low molecular weight heparins (LMWHs), publications from 27 orthopaedic trials and 35 studies of patients undergoing general or gynaecological surgery were scrutinized and subjected to a partial meta-analysis. In orthopaedic surgery, LMWHs were superior ...... with the former. Compared with unfractionated heparin, LMWHs did not reduce the postoperative mortality rate, nor did they cause haemorrhage. LMWHs provide safe and efficient prophylaxis by administration once daily....

  12. High molecular weight polysaccharide that binds and inhibits virus

    Energy Technology Data Exchange (ETDEWEB)

    Konowalchuk, Thomas W.; Konowalchuk, Jack

    2017-07-18

    This invention provides a high molecular weight polysaccharide capable of binding to and inhibiting virus and related pharmaceutical formulations and methods of inhibiting viral infectivity and/or pathogenicity, as well as immunogenic compositions. The invention further includes methods of inhibiting the growth of cancer cells and of ameliorating a symptom of aging. Additionally, the invention provides methods of detecting and/or quantifying and/or isolating viruses.

  13. Physical Properties of Low-Molecular Weight Polydimethylsiloxane Fluids

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Christine Cardinal [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Graham, Alan [Univ. of Colorado, Denver, CO (United States); Nemer, Martin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Phinney, Leslie M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Garcia, Robert M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Soehnel, Melissa Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stirrup, Emily Kate [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-02-01

    Physical property measurements including viscosity, density, thermal conductivity, and heat capacity of low-molecular weight polydimethylsiloxane (PDMS) fluids were measured over a wide temperature range (-50°C to 150°C when possible). Properties of blends of 1 cSt and 20 cSt PDMS fluids were also investigated. Uncertainties in the measurements are cited. These measurements will provide greater fidelity predictions of environmental sensing device behavior in hot and cold environments.

  14. High molecular weight polysaccharide that binds and inhibits virus

    Science.gov (United States)

    Konowalchuk, Thomas W

    2014-01-14

    This invention provides a high molecular weight polysaccharide capable of binding to and inhibiting virus and related pharmaceutical formulations and methods on inhibiting viral infectivity and/or pathogenicity, as well as immunogenic compositions. The invention further methods of inhibiting the growth of cancer cells and of ameliorating a symptom of aging. Additionally, the invention provides methods of detecting and/or quantifying and/or isolating viruses.

  15. Low-molecular-weight chitosans: Preparation and characterization

    Czech Academy of Sciences Publication Activity Database

    Tishchenko, Galina; Šimůnek, Jiří; Brus, Jiří; Netopilík, Miloš; Pekárek, Michal; Walterová, Zuzana; Koppová, Ingrid; Lenfeld, Jiří

    2011-01-01

    Roč. 86, č. 2 (2011), s. 1077-1081 ISSN 0144-8617 R&D Projects: GA ČR(CZ) GA525/08/0803 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z50450515 Keywords : low-molecular-weight chitosan s * chitooligosaccharides * oxidative depolymerization Subject RIV: ED - Physiology Impact factor: 3.628, year: 2011

  16. Steroidogenic activity of high molecular weight forms of ACTH

    International Nuclear Information System (INIS)

    Gasson, J.C.

    1979-01-01

    The relative steroidogenic potencies of high molecular weight forms of adrenocorticotropic hormone (ACTH) were investigated using in vitro bioassays. In order to prepare pools of separated pro-ACTH/endorphin, ACTH biosynthetic intermediate and glycosylated ACTH (1-39), the protein present in serum-free tissue culture medium obtained from cultured AtT-20/D-16v mouse pituitary tumor cells was concentrated and fractionated by gel filtration. Based on sodium dodecyl sulfate polyacrylamide gel electrophoresis, over 97% of the immunoactive ACTH in each pool had the appropriate molecular weight. Suspensions of isolated rat and guinea pig adrenal cortical cells were prepared by enzymatic dissociation and mechanical dispersion. Cells were incubated in complete tissue culture medium overnight then used in a 2 hour steroid production assay. Synthetic hACTH(1-39) was used as a bioassay and immunoassay standard. The amounts of pro-ACTH/endorphin, ACTH biosynthetic intermediate and glycosylated ACTH(1-39) bioassayed were estimated by ACTH(17-24) radioimmunoassay. All three high molecular weight forms of ACTH were capable of stimulating the same maximal level of steroidogenesis, by both isolated rat and guinea pig adrenal cells, as hACTH(1-39). Glycosylated ACTH(1-39) was equipotent with hACTH(1-39); pro-ACTH/endorphin and ACTH biosynthetic intermediate were two orders of magnitude less potent than hACTH(1-39) in both bioassay systems

  17. Radiation degradation of molasses pigment. 2. Molecular weight fraction

    International Nuclear Information System (INIS)

    Sawai, Teruko; Sekiguchi, Masayuki; Tanabe, Hiroko

    1996-01-01

    Water demand in Tokyo has increased rapidly. Because of the scarcity of water sources within the city, Tokyo is dependent on water from other prefectures. Recycling of municipal effluent is an effective means of coping with water shortage in Tokyo. We have studied the radiation treatment of waste water for recycling. The degradation of molasses pigments in waste water from yeast factory by radiation was investigated. The dialyzed molasses pigments and non-dialyzed samples in waste waters were compared in chromaticity, UV absorption, color different and COD. The dialysis and fractionation by permeable membrane were carried out with Seamless Cellulose tubing (Union Carbide Corporation) and spectra/Por membrane (Spectrum Medical Industries INC.) The TOC values decreased and the dark brown color faded with increasing dose. The high molecular weight components of molasses pigment were degraded to lower molecular weight substances and decomposed to carbon dioxide. The relationships between the value of chromaticity/TOC and molecular weight of molasses pigments were obtained by radiation. (author)

  18. A simple method for bracketing absolute divergence times on molecular phylogenies using multiple fossil calibration points.

    Science.gov (United States)

    Marshall, Charles R

    2008-06-01

    A central challenge facing the temporal calibration of molecular phylogenies is finding a quantitative method for estimating maximum age constraints on lineage divergence times. Here, I provide such a method. This method requires an ultrametric tree generated without reference to the fossil record. Exploiting the fact that the relative branch lengths on the ultrametric tree are proportional to time, this method identifies the lineage with the greatest proportion of its true temporal range covered by the fossil record. The oldest fossil of this calibration lineage is used as the minimum age constraint. The maximum age constraint is obtained by adding a confidence interval onto the end point of the calibration lineage, thus making it possible to bracket the true divergence times of all lineages on the tree. The approach can also identify fossils that have been grossly misdated or misassigned to the phylogeny. The method assumes that the relative branch lengths on the ultrametric tree are accurate and that fossilization is random. The effect of violations of these assumptions is assessed. This method is simple to use and is illustrated with a reanalysis of Near et al.'s turtle data.

  19. Alkyl cross-linked low molecular weight polypropyleneimine dendrimers as efficient gene delivery vectors

    Directory of Open Access Journals (Sweden)

    Faezeh Moghadam Ariaee

    2016-10-01

    Conclusion: Our results indicated that oligomerization of low molecular weight PPI (PPI G2-alkyl-PPI G2 conjugate could be an approach to increase the transfection efficiency and to lower the cytotoxicity of low molecular weight polycations.

  20. Photoinduced optical anisotropy in azobenzene methacrylate block copolymers: Influence of molecular weight and irradiation conditions

    DEFF Research Database (Denmark)

    Gimeno, Sofia; Forcen, Patricia; Oriol, Luis

    2009-01-01

    The photoinduced anisotropy in a series of azomethacrylate block copolymers with different Molecular weights and azo contents has been investigated under several irradiation conditions. Depending on molecular weight and composition, different microstructures (disordered, lamellar, spherical) appe...

  1. Light-weight integration of molecular biological databases.

    Science.gov (United States)

    Philippi, Stephan

    2004-01-01

    Due to the increasing number of molecular biological databases and the exponential growth of their contents, database integration is an important topic of research in bioinformatics. Existing approaches in this area have in common that considerable efforts are needed to provide integrated access to heterogeneous data sources. This article describes the LIMBO architecture as a light-weight approach to molecular biological database integration. By building systems upon this architecture, the efforts needed for database integration can be significantly lowered. As an illustration of the principle usefulness of the underlying ideas, a prototypical implementation based upon the LIMBO architecture is described. This implementation is exclusively based on freely available open source components like the PostgreSQL database management system and the BioRuby project. Additional files and modified components are available upon request from the author.

  2. Cyclic impact compaction of ultra high molecular weight polyethylene powder

    Science.gov (United States)

    Zlobin, B. S.; Shtertser, A. A.; Kiselev, V. V.; Shemelin, S. D.; Poluboyarov, V. A.; Zhdanok, A. A.

    2017-05-01

    Bulk specimens of GUR 4150 ultra-high-molecular-weight polyethylene with a molar mass of 9.2 · 106 g/mol are obtained by cyclic impact compaction. During compaction, the material remains in the solid state, which ensures the preservation of the crystalline phase with a volume fraction of up to 66%. The strength properties of the specimens are not inferior to those of the products obtained using the industrial hot molding process. It is shown that the method described here is suitable for producing compacts with micro- and nanosized additives.

  3. Low molecular weight block copolymers as plasticizers for polystyrene

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Karsten; Nielsen, Charlotte Juel; Hvilsted, Søren

    2005-01-01

    Polystyrene-b-alkyl, polystyrene-b-polybutadiene-b-polystyrene, and polystyrene-b-poly(propylene glycol)monotridecyl ether were synthesized using macro initiators and atom transfer radical polymerization or by esterifications of homopolymers. The aim was a maximum molecular weight of 4 kg...... for polystyrene-b-polyisoprene-b-polystyrene (SIS) block copolymers. The end use properties of SIS plasticized with polystyrene-b-alkyl, measured as tensile strength, is higher than for SIS plasticized with dioctyl adipate. The polystyrene-b-polybutadiene-b-polystyrene and polystyrene-bpoly(propylene glycol...

  4. Comparative study of two ATP : L-arginine phosphotransferases of molecular weight 84 000.

    Science.gov (United States)

    Thiem, N V; Lacombe, G; Thoai, N V

    1975-01-23

    Solen ensisensis muscle arginine kinase (ATP : L-arginine phosphotransferase, EC 2.7.3.3) was isolated in an homogeneous state. Its molecular weight was found to be about 80 000. The properties of this enzyme were compared with those of arginine kinase from Sipunculus nudus, an enzyme which also has a molecular weight of about 80 000. Both enzymes have several reactive thiol groups (8 thiol groups in the Solen kinase and 12 in the Sipunculus enzyme were titrateable with 5,5'-dithio-bis-(2-nitrobenzoic) acid and histidine residues (both enzymes have 6 reactive histidine residues). These kinases were, therefore, highly susceptible to oxidation. Both enzymes show the same pH optimum and absolute specificity towards the guanidine substrate, L-arginine. The reaction kinetics of both enzymes are of the sequential type. In the presence of alpha-aminoacids of Mg2+-ADP, similar spectral effects were obtained. The enzymes differ in their enzymic activities and in their rate of recovery following urea denaturation. The most important difference that appeared to be a special feature of the Sipunculus enzyme is that the spectrum of the Mg2+-ADP-enzyme complex is strongly intensified by L-arginine.

  5. Exploiting Molecular Weight Distribution Shape to Tune Domain Spacing in Block Copolymer Thin Films.

    Science.gov (United States)

    Gentekos, Dillon T; Jia, Junteng; Tirado, Erika S; Barteau, Katherine P; Smilgies, Detlef-M; DiStasio, Robert A; Fors, Brett P

    2018-04-04

    We report a method for tuning the domain spacing ( D sp ) of self-assembled block copolymer thin films of poly(styrene- block-methyl methacrylate) (PS- b-PMMA) over a large range of lamellar periods. By modifying the molecular weight distribution (MWD) shape (including both the breadth and skew) of the PS block via temporal control of polymer chain initiation in anionic polymerization, we observe increases of up to 41% in D sp for polymers with the same overall molecular weight ( M n ≈ 125 kg mol -1 ) without significantly changing the overall morphology or chemical composition of the final material. In conjunction with our experimental efforts, we have utilized concepts from population statistics and least-squares analysis to develop a model for predicting D sp based on the first three moments of the MWDs. This statistical model reproduces experimental D sp values with high fidelity (with mean absolute errors of 1.2 nm or 1.8%) and provides novel physical insight into the individual and collective roles played by the MWD moments in determining this property of interest. This work demonstrates that both MWD breadth and skew have a profound influence over D sp , thereby providing an experimental and conceptual platform for exploiting MWD shape as a simple and modular handle for fine-tuning D sp in block copolymer thin films.

  6. Modernization of Enoxaparin Molecular Weight Determination Using Homogeneous Standards

    Directory of Open Access Journals (Sweden)

    Katelyn M. Arnold

    2017-07-01

    Full Text Available Enoxaparin is a low-molecular weight heparin used to treat thrombotic disorders. Following the fatal contamination of the heparin supply chain in 2007–2008, the U.S. Pharmacopeia (USP and U.S. Food and Drug Administration (FDA have worked extensively to modernize the unfractionated heparin and enoxaparin monographs. As a result, the determination of molecular weight (MW has been added to the monograph as a measure to strengthen the quality testing and to increase the protection of the global supply of this life-saving drug. The current USP calibrant materials used for enoxaparin MW determination are composed of a mixture of oligosaccharides; however, they are difficult to reproduce as the calibrants have ill-defined structures due to the heterogeneity of the heparin parent material. To address this issue, we describe a promising approach consisting of a predictive computational model built from a library of chemoenzymatically synthesized heparin oligosaccharides for enoxaparin MW determination. Here, we demonstrate that this test can be performed with greater efficiency by coupling synthetic oligosaccharides with the power of computational modeling. Our approach is expected to improve the MW measurement for enoxaparin.

  7. Obstetric outcome with low molecular weight heparin therapy during pregnancy.

    LENUS (Irish Health Repository)

    Donnelly, J

    2012-01-01

    This was a prospective study of women attending a combined haematology\\/obstetric antenatal clinic in the National Maternity Hospital (2002-2008). Obstetric outcome in mothers treated with low molecular weight heparin (LMWH) was compared to the general obstetric population of 2006. There were 133 pregnancies in 105 women. 85 (63.9%) received prophylactic LMWH and 38 (28.6%) received therapeutic LMWH in pregnancy. 10 (7.5%) received postpartum prophylaxis only. The perinatal mortality rate was 7.6\\/1000 births. 14 (11.3%) women delivered preterm which is significantly higher than the hospital population rate (5.7%, p<0.05). Despite significantly higher labour induction rates (50% vs 29.2% p<0.01), there was no difference in CS rates compared to the general hospital population (15.4% vs 18.9%, NS). If carefully managed, these high-risk women can achieve similar vaginal delivery rates as the general obstetric population.

  8. High molecular weight polypeptide bands specific for equine herpesvirus 4.

    Science.gov (United States)

    Zheng, M; Love, D N; Sabine, M

    1995-09-01

    Serum neutralisation (SN) and immunoblotting were used in attempts to distinguish between natural infections with the closely related viruses equine herpesvirus 1 (EHV-1) and equine herpes-virus 4 (EHV-4). Horse sera (n = 323) collected in 1990 from studs with no experience of EHV-1 abortions as well as 197 sera collected in 1992 from studs with a history of EHV-1 abortions were tested by SN. The two groups differed in the proportion with measurable EHV-1 antibody, the 1992 group being significantly higher. Both groups had high proportions with EHV-4 antibody and no serum had antibody to EHV-1 alone. Pools of positive sera were prepared as probes in immunoblots. High molecular weight (> 200 kDa) polypeptide bands specific for EHV-4 were detected. No bands specific for EHV-1 only were found. The specific EHV-4 polypeptides shared some properties with gp2 of EHV-1.

  9. Low-molecular-weight carbohydrates from red seaweeds

    International Nuclear Information System (INIS)

    Duarte, M.E.R.; Tischer, C.A.; Gorin, P.A.J.; Noseda, M.D.

    1997-01-01

    Red algae (Rhodophyta) produce, as their principal photosynthetic metabolites, low-molecular-weight carbohydrates and polyols. The former are heterosides consisting of galactose and glycerol and are produced by all the orders of Phodophyta except the ceramiales. They are named: floridoside [α-D-galactopyranosyl (1->2)-glycerol], isofloridoside D-form [α-D-galactopyranosyl-(1->)D-glycerol] and L-form [α-D-galactopyranosyl-(1->1)-L-glycerol] (Meng et al., 1987, Karsten et al., 1993). The Ceramiales synthesize the chemically related digeneaside [α-D-mannopyranosyl-(1->2)-L-glycerate] (Kirst, 1980). Some of the red seaweeds also produce polyols such as dulcitol and D-sorbitol (Karsten et al., 1992). (author)

  10. Low-molecular-weight carbohydrates from red seaweeds

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, M.E.R.; Tischer, C.A.; Gorin, P.A.J.; Noseda, M.D. [Parana Univ., Curitiba, PR (Brazil). Dept. de Bioquimica

    1997-12-31

    Red algae (Rhodophyta) produce, as their principal photosynthetic metabolites, low-molecular-weight carbohydrates and polyols. The former are heterosides consisting of galactose and glycerol and are produced by all the orders of Phodophyta except the ceramiales. They are named: floridoside [{alpha}-D-galactopyranosyl (1->2)-glycerol], isofloridoside D-form [{alpha}-D-galactopyranosyl-(1->)D-glycerol] and L-form [{alpha}-D-galactopyranosyl-(1->1)-L-glycerol] (Meng et al., 1987, Karsten et al., 1993). The Ceramiales synthesize the chemically related digeneaside [{alpha}-D-mannopyranosyl-(1->2)-L-glycerate] (Kirst, 1980). Some of the red seaweeds also produce polyols such as dulcitol and D-sorbitol (Karsten et al., 1992). (author) 4 refs., 8 figs., 1 tabs.

  11. High Molecular Weight Polybenzimidazole Membranes for High Temperature PEMFC

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Cleemann, Lars Nilausen; Steenberg, T.

    2014-01-01

    tensile strength of 30.3 MPa at room temperature or 7.3 MPa at 130 °C and a proton conductivity of 0.14 S cm–1 at 160 °C. Fuel cell tests with H2 and air at 160 °C showed high open circuit voltage, power density and a low degradation rate of 1.5 μV h–1 at a constant load of 300 mA cm–2.......High temperature operation of proton exchange membrane fuel cells under ambient pressure has been achieved by using phosphoric acid doped polybenzimidazole (PBI) membranes. To optimize the membrane and fuel cells, high performance polymers were synthesized of molecular weights from 30 to 94 k...

  12. Early weight changes after birth and serum high-molecular-weight adiponectin level in preterm infants.

    Science.gov (United States)

    Yoshida, Tomohide; Nagasaki, Hiraku; Asato, Yoshihide; Ohta, Takao

    2011-12-01

    Extra-uterine growth retardation (EUGR) is associated with an increased risk for cardiometabolic diseases later in life. The aim of the present study was to examine the relationship between early weight change after birth in preterm infants and adiponectin (adn) multimeric complexes. Subjects included 28 preterm infants born between weeks 24 and 33 of gestation. Serum adn multimeric complexes and the anthropometric parameters were measured in preterm infants at birth and at corrected term. Bodyweight (BW) decreased during the first week of life, with birthweight restored at approximately 19 days after birth. Nineteen of the subjects had EUGR at corrected term. Total (T)-adn, high-molecular-weight (H)-adn, and the ratio of H-adn to T-adn (H/T-adn) were significantly elevated at corrected term than at birth. Postmenstrual age, birthweight, birth length and lowest BW after birth were positively correlated with H-adn and H/T-adn. Weight reduction after birth was negatively correlated with H-adn. Age to restore birthweight was negatively correlated with T-adn, H-adn and H/T-adn. Stepwise multiple regression analysis indicated age to restore birthweight as the major predictor of T-adn and H-adn. Early weight changes after birth may alter serum adn level in preterm infants at corrected term. The appropriate nutritional support in the early postnatal period could reduce the prevalence of EUGR and the future risk for cardiometabolic diseases. © 2011 The Authors. Pediatrics International © 2011 Japan Pediatric Society.

  13. Low Molecular Weight Norbornadiene Derivatives for Molecular Solar-Thermal Energy Storage.

    Science.gov (United States)

    Quant, Maria; Lennartson, Anders; Dreos, Ambra; Kuisma, Mikael; Erhart, Paul; Börjesson, Karl; Moth-Poulsen, Kasper

    2016-09-05

    Molecular solar-thermal energy storage systems are based on molecular switches that reversibly convert solar energy into chemical energy. Herein, we report the synthesis, characterization, and computational evaluation of a series of low molecular weight (193-260 g mol(-1) ) norbornadiene-quadricyclane systems. The molecules feature cyano acceptor and ethynyl-substituted aromatic donor groups, leading to a good match with solar irradiation, quantitative photo-thermal conversion between the norbornadiene and quadricyclane, as well as high energy storage densities (396-629 kJ kg(-1) ). The spectroscopic properties and energy storage capability have been further evaluated through density functional theory calculations, which indicate that the ethynyl moiety plays a critical role in obtaining the high oscillator strengths seen for these molecules. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  14. The measurement of the molecular weight of humic acid by ultracentrifugation

    International Nuclear Information System (INIS)

    Gardner, M.P.

    1989-07-01

    This report is concerned with the application of ultracentrifuge methods to the determination of humic acid molecular weights. The work has been undertaken as part of the Co-Co club intercomparison exercise on humic acid characterisation. Knowledge of the molecular weight distribution of humic acid will be an important parameter in assessing the likely physical and chemical behaviour under the near-field environment. Molecular weights of a sample of purified Aldrich humic acid have been obtained by sedimentation velocity and sedimentation equilibrium studies using an analytical ultracentrifuge. The results have shown the material to be polydisperse with a weight average molecular weight in the region 2700 to 4000. (author)

  15. Glomerular sieving of high molecular weight proteins in proteinuric rats

    International Nuclear Information System (INIS)

    Bertolatus, J.A.; Abuyousef, M.; Hunsicker, L.G.

    1987-01-01

    To characterize the permeability of the glomerular capillary wall to high molecular weight proteins in normal and proteinuric rats, we determined the glomerular sieving coefficients (GSC) of radioiodinated marker proteins of known size and charge by means of a paired label, tissue accumulation method previously validated in this laboratory. In one group of rats (Series A) the GSCs of 125 I-anionic IgG (aIgG-molecular weight [mol wt] 150,000, pI 4.9) and 131 I-neutral IgG (nIgG-pI 7.4 to 7.6) were measured simultaneously. In Series B, the GSC of a second anionic marker, 131 I-human ceruloplasmin (Crp-mol wt 137,000, pI 4.9) was compared to that of 125 I-nIgG. As in the previous report, the labeled proteins were not degraded or deiodinated during the 20 minute clearance period for GSC determination. Within Series A and B, three subgroups of rats were studied: control saline-infused rats, rats made acutely proteinuric by infusion of the polycation hexadimethrine (HDM), and rats with chronic doxorubicin (Adriamycin-Adria) nephrosis. In the control rats, GSCs for the anionic markers aIgG (Series A) or Crp (Series B) were significantly greater than that of nIgG (both series). These large proteins crossed the filtration barrier by a different pathway from that available to smaller neutral molecules the size of albumin, which in our previous study had a much higher GSC than a native, anionic albumin marker. In a third group of control rats only (Series C), the GSCs of native anionic bovine albumin (BSA) and nIgG were compared directly. The GSC of BSA (0.0029) was only slightly larger than the GSC of nIgG (0.0025), indicating that most of the native albumin crosses the glomerular capillary wall via a nonselective pathway similar to that available to nIgG. The results in the control groups are compatible with recently-described heteroporous models of glomerular size selectivity

  16. Optimization of parameters for coverage of low molecular weight proteins.

    Science.gov (United States)

    Müller, Stephan A; Kohajda, Tibor; Findeiss, Sven; Stadler, Peter F; Washietl, Stefan; Kellis, Manolis; von Bergen, Martin; Kalkhof, Stefan

    2010-12-01

    Proteins with molecular weights of cycle control. Despite their importance, the coverage of smaller proteins in standard proteome studies is rather sparse. Here we investigated biochemical and mass spectrometric parameters that influence coverage and validity of identification. The underrepresentation of low molecular weight (LMW) proteins may be attributed to the low numbers of proteolytic peptides formed by tryptic digestion as well as their tendency to be lost in protein separation and concentration/desalting procedures. In a systematic investigation of the LMW proteome of Escherichia coli, a total of 455 LMW proteins (27% of the 1672 listed in the SwissProt protein database) were identified, corresponding to a coverage of 62% of the known cytosolic LMW proteins. Of these proteins, 93 had not yet been functionally classified, and five had not previously been confirmed at the protein level. In this study, the influences of protein extraction (either urea or TFA), proteolytic digestion (solely, and the combined usage of trypsin and AspN as endoproteases) and protein separation (gel- or non-gel-based) were investigated. Compared to the standard procedure based solely on the use of urea lysis buffer, in-gel separation and tryptic digestion, the complementary use of TFA for extraction or endoprotease AspN for proteolysis permits the identification of an extra 72 (32%) and 51 proteins (23%), respectively. Regarding mass spectrometry analysis with an LTQ Orbitrap mass spectrometer, collision-induced fragmentation (CID and HCD) and electron transfer dissociation using the linear ion trap (IT) or the Orbitrap as the analyzer were compared. IT-CID was found to yield the best identification rate, whereas IT-ETD provided almost comparable results in terms of LMW proteome coverage. The high overlap between the proteins identified with IT-CID and IT-ETD allowed the validation of 75% of the identified proteins using this orthogonal fragmentation technique. Furthermore, a new

  17. Effect of the molecular weight of sodium polystyrene sulfonate on the properties of coal water slurry

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Y.; Gao, F.; Li, Y. [Ningxia University, Yinchuan (China)

    2006-06-15

    Three sodium polystyrene sulfonate (PSS) additives with different molecular weight and 8 coals are selected to evaluate the effect of molecular weight of PSS on the properties of coal water slurry (CWS). The range of weight average molecular weight of PSS for preparing coal water slurry is from 53400 to 333900. The results indicate that the slurryability of CWS of 8 coals decreases as the molecular weight of PSS increases. The relation between slurry ability of CWS and molecular weight of PSS is attributed to the adsorption of PSS on the coal particles. The adsorption quantity of PSS with low molecular weight on the coal particles is larger than that of PSS with high molecular weight. On the other hand, the rheological behavior of CWS of 8 coals is changed from dilatant flow to pseudoplastic one as the increase of molecular weight of PSS. The static stability of CWS is also improved with increasing molecular weight of PSS. 9 refs., 3 figs., 3 tabs.

  18. Influences of molecular weight on curing effect of epoxy resin irradiated by electron beam

    International Nuclear Information System (INIS)

    Sui Gang; Liang Ji; Li Dan; Zhang Zuoguang; Chen Huijuan

    2004-01-01

    The influences of molecular weight on electron beam (EB) curing in epoxy resins were studied. The rate of radiation reaction in epoxy resin systems decreases with the increasing molecular weight. Under the low radiation dose, the curing thickness and curing degree is small for samples with high molecular weight. The effect of molecular weight decreases with the increasing radiation dose. The glass transition temperature (Tg) and the storage modulus (E') are under the control of curing degree in samples, and the molecular weight will play a role on the samples with similar curing degree. After heat treatment, the Tg and E' of epoxy resins cured by radiation will increase. The molecular weight is directly associated with effect of heat treatment

  19. Molecular imprinted polymer-coated optical fiber sensor for the identification of low molecular weight molecules.

    Science.gov (United States)

    Lépinay, Sandrine; Ianoul, Anatoli; Albert, Jacques

    2014-10-01

    A biomimetic optical probe for detecting low molecular weight molecules (maltol, 3-hydroxy-2-methyl-4H-pyran-4-one, molecular weight of 126.11 g/mol), was designed, fabricated, and characterized. The sensor couples a molecular imprinted polymer (MIP) and the Bragg grating refractometry technology into an optical fiber. The probe is fabricated first by inscribing tilted grating planes in the core of the fiber, and then by photopolymerization to immobilize a maltol imprinted MIP on the fiber cladding surface over the Bragg grating. The sensor response to the presence of maltol in different media is obtained by spectral interrogation of the fiber transmission signal. The results showed that the limit of detection of the sensor reached 1 ng/mL in pure water with a sensitivity of 6.3 × 10(8)pm/M. The selectivity of the sensor against other compounds and its reusability were also studied experimentally. Finally, the unambiguous detection of concentrations as little as 10nM of maltol in complex media (real food samples) by the MIP-coated tilted fiber Bragg grating sensor was demonstrated. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Protamine reversal of low molecular weight heparin: clinically effective?

    Science.gov (United States)

    van Veen, Joost J; Maclean, Rhona M; Hampton, Kingsley K; Laidlaw, Stuart; Kitchen, Steve; Toth, Peter; Makris, Mike

    2011-10-01

    Low molecular weight heparins (LMWHs) are frequently used in the prophylaxis or treatment of venous thrombosis, acute coronary syndromes and peri-operative bridging. Major bleeding occurs in 1-4% depending on dose and underlying condition. Protamine is recommended for reversal but only partially reverses the anti-Xa activity and there are very limited data on clinical effectiveness. We retrospectively studied the effect of emergency reversal of LMWH with protamine in actively bleeding patients and patients requiring emergency surgery in our institution. Eighteen patients were identified through haematology referral/pharmacy records of protamine prescriptions between 1998 and 2009. Case notes were checked for the reversal indication, type/dose of LMWH, dose and clinical response to protamine, timing in relation to the last dose of LMWH and anti-Xa levels before and after protamine. All but one patient received enoxaparin. Fourteen were actively bleeding, three required emergency surgery without active bleeding and one had an accidental overdose without bleeding. The three patients requiring surgery had an uneventful procedure. In 12 of 14 patients with active bleeding, protamine could be evaluated. Bleeding stopped in eight. In the four with continuing bleeding, one had an additional coagulopathy. Protamine only partially affected anti-Xa levels. Protamine may be of use in reversing bleeding associated with LMWH but not in all patients. Anti-Xa levels were useful to assess the amount of anticoagulation before protamine administration but unhelpful in assessing its effect. Better reversal agents and methods to monitor LMWH therapy are required.

  1. Starburst low-molecular weight polyethylenimine for efficient gene delivery.

    Science.gov (United States)

    Zhao, Yanjun; Yang, Rulei; Liu, Dong; Sun, Mingjing; Zhou, Lijun; Wang, Zheng; Wan, Ying

    2012-01-01

    Low-molecular weight polyethylenimine (LMW PEI) shows the advantage of low-cytotoxicity, but has been inefficient in gene delivery as a consequence of the low-charge density. A number of previous studies employed the approach of crosslinking to solve this problem. In this study, a starburst LMW PEI gene vector has been developed. It has a polyamidoamine (PAMAM) core conjugated with a shell composed of LWM PEI and polyethylene glycol (PEG), that is PAMAM-PEI-PEG. Plasmid DNA (pEGFP-N1) and human cervix epithelial carcinoma (HeLa) cells were used in the study. The results showed that the starburst LMW PEI could effectively condense DNA at N/P above 5. The polyplexes had a size of about 500 nm and a nearly neutral surface because of the PEG shielding effect. This novel gene vector is able to maintain the low-cytotoxicity of LMW PEI, whereas its transfection efficiency was significantly improved. Copyright © 2011 Wiley Periodicals, Inc.

  2. Antiaging activity of low molecular weight peptide from Paphia undulate

    Science.gov (United States)

    Chen, Xin; Cai, Bingna; Chen, Hua; Pan, Jianyu; Chen, Deke; Sun, Huili

    2013-05-01

    Low molecular weight peptide (LMWP) was prepared from clam Paphia undulate and its antiaging effect on D-galactose-induced acute aging in rats, aged Kunming mice, ultraviolet-exposed rats, and thermally injured rats was investigated. P. undulate flesh was homogenized and digested using papain under optimal conditions, then subjected to Sephadex G-25 chromatography to isolate the LMWP. Administration of LMWP significantly reversed D-galactose-induced oxidative stress by increasing the activities of glutathione peroxidase (GPx) and catalase (CAT), and by decreasing the level of malondialdehyde (MDA). This process was accompanied by increased collagen synthesis. The LMWP prevented photoaging and promoted dermis recovery and remission of elastic fiber hyperplasia. Furthermore, treatment with the LMWP helped to regenerate elastic fibers and the collagen network, increased superoxide dismutase (SOD) in the serum and significantly decreased MDA. Thermal scald-induced inflammation and edema were also relieved by the LWMP, while wound healing in skin was promoted. These results suggest that the LMWP from P. undulate could serve as a new antiaging substance in cosmetics.

  3. Arterial indications for the low molecular weight heparins

    Directory of Open Access Journals (Sweden)

    Ageno Walter

    2001-09-01

    Full Text Available Abstract Antithrombotic treatment is of proven importance in patients with acute coronary syndromes. There is now accumulating evidence from several clinical trials in patients with unstable angina pectoris that the low molecular weight heparins (LMWHs are at least as effective as unfractionated heparin. The LMWHs are easier to use, with the potential to facilitate long-term outpatient treatment. The results of the trials have actually failed to show any clear advantage, however, of the LMWHs over the standard antiplatelet treatment, despite the evidence of a sustained hypercoagulability. Potentially, the use of higher doses of LMWHs could improve the outcomes, but this is as yet unproven and could be associated with unacceptably increased risk of bleeding. During the acute phase of a stroke, aspirin is the first choice of antithrombotic drug because it reduces the risk of recurrent stroke. LMWH cannot be recommended as an antithrombotic agent for the acute treatment of stroke. Prophylactic use of low dose LMWH for the prevention of venous thromboembolism should be considered in every patient with a stroke.

  4. High molecular weight plant heteropolysaccharides stimulate fibroblasts but inhibit keratinocytes.

    Science.gov (United States)

    Shahbuddin, Munira; Shahbuddin, Dahlia; Bullock, Anthony J; Ibrahim, Halijah; Rimmer, Stephen; MacNeil, Sheila

    2013-06-28

    Konjac glucomannan (KGM) is a natural polysaccharide of β(1-4)-D-glucomannopyranosyl backbone of D-mannose and D-glucose derived from the tuber of Amorphophallus konjac C. Koch. KGM has been reported to have a wide range of activities including wound healing. In this study we examined KGM extracts prepared from five plant species, (Amorphophallus konjac Koch, Amorphophallus oncophyllus, Amorphophallus prainii, Amorphophallus paeoniifolius and Amorphophallus elegans) for their effects on cultured human keratinocytes and fibroblasts. Extracts from A. konjac Koch, A. oncophyllus and A. prainii (but not from A. paeoniifolius or A. elegans) stimulated fibroblast proliferation both in the absence and presence of serum. However, these materials inhibited keratinocyte proliferation. The fibroblast stimulatory activity was associated with high molecular weight fractions of KGM and was lost following ethanol extraction or enzyme digestion with β-mannanase. It was also reduced by the addition of concanavalin A but not mannose suggesting that these heteropolysaccharides are acting on lectins but not via receptors specific to mannose. The most dramatic effect of KGM was seen in its ability to support fibroblasts for 3weeks under conditions of deliberate media starvation. This effect did not extend to supporting keratinocytes under conditions of media starvation but KGM did significantly help support adipose derived stem cells under media starvation conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Intravitreal low molecular weight heparin in PVR surgery.

    Directory of Open Access Journals (Sweden)

    Kumar Atul

    2003-01-01

    Full Text Available Purpose: To evaluate the efficacy of low molecular weight heparin (LMWH in prevention of postoperative fibrin formation following vitreoretinal surgery with proliferative vitreoretinopathy (PVR. Material and Methods: Thirty consecutive patients of retinal detachment with advanced PVR were enrolled in the study. They were randomised to study and control groups (n = 15 each. Study group patients received vitreoretinal surgery with 5 IU/cc of LMWH in vitrectomy infusion fluid. The control group patients received vitroretinal surgery without heparin in the infusion fluid. Patients were followed up at 1 week, 1 month and 3 months after surgery. Postoperative bleeding, media clarity, best-corrected visual acuity and success of the surgery at the end of 3 months were compared between the two groups. Results: At each follow-up visit, the study group showed a better media clarity, which was statistically significant ( P = 0.0042. The study group had a 50% better chance of retinal reattachment compared to the control group. Five patients had intraoperative bleeding in the study group (33% compared to 3 patients in the control group (20%. Conclusion: Use of intravitreal LMWH prevents postoperative fibrin formation and is beneficial in repair of retinal detachments with PVR.

  6. The Effect of Low Molecular Weight Heparins on Fracture Healing.

    Science.gov (United States)

    Kapetanakis, Stylianos; Nastoulis, Evangelos; Demesticha, Theano; Demetriou, Thespis

    2015-01-01

    Venous Thromboembolism is a serious complication in the trauma patient. The most commonly studied and used anticoagulant treatment in prophylaxis of thrombosis is heparin. The prolonged use of unfractionated heparin has been connected with increased incidence of osteoporotic fractures. Low molecular-weight-heparins (LMWHs) have been the golden rule in antithrombotic therapy during the previous two decades as a way to overcome the major drawbacks of unfractioned heparin. However there are few studies reporting the effects of LMWHs on bone repair after fractures. This review presents the studies about the effects of LMWHs on bone biology (bone cells and bone metabolism) and underlying the mechanisms by which LMWHs may impair fracture healing process. The authors' research based on literature concluded that there are no facts and statistics for the role of LMWHs on fracture healing process in humans and the main body of evidence of their role comes from in vitro and animal studies. Further large clinical studies designed to compare different types of LMWHs, in different dosages and in different patient or animal models are needed for exploring the effects of LMWHs on fracture healing process.

  7. Disassembled DJ-1 high molecular weight complex in cortex mitochondria from Parkinson's disease patients

    Directory of Open Access Journals (Sweden)

    Adler Charles

    2009-07-01

    Full Text Available Abstract Correction to Nural H, He P, Beach T, Sue L, Xia W, Shen Y. Disassembled DJ-1 high molecular weight complex in cortex mitochondria from Parkinson's disease patients Molecular Neurodegeneration 2009, 4:23.

  8. Micellization of symmetric PEP-PEO block copolymers in water molecular weight dependence

    CERN Document Server

    Kaya, H; Allgaier, J; Stellbrink, J; Richter, D

    2002-01-01

    The micellar behaviour of the amphiphilic block copolymer poly-(ethylene-propylene)-poly-(ethylene oxide) (PEP-PEO) in aqueous solution has been studied with small-angle neutron scattering. The polymer was studied over a wide range of molecular weights, always keeping the volume of the blocks equal. The scattering behaviour of the solutions showed that a morphological transition takes place upon lowering the molecular weight. The high molecular weight block copolymers all build spherical, monodisperse micelles with large aggregation numbers. At low molecular weights, however, cylindrical micelles are formed. An interesting intermediate case is represented by the PEP2-PEO2 system, in which a morphological transition occurs upon dilution. (orig.)

  9. Lunch-time food choices in preschoolers: relationships between absolute and relative intake of different food categories, and appetitive characteristics and weight

    Science.gov (United States)

    Carnell, S; Pryor, K; Mais, LA; Warkentin, S; Benson, L; Cheng, R

    2016-01-01

    Children’s appetitive characteristics measured by parent-report questionnaires are reliably associated with body weight, as well as behavioral tests of appetite, but relatively little is known about relationships with food choice. As part of a larger preloading study, we served 4-5y olds from primary school classes five school lunches at which they were presented with the same standardized multi-item meal. Parents completed Child Eating Behavior Questionnaire (CEBQ) sub-scales assessing satiety responsiveness (CEBQ-SR), food responsiveness (CEBQ-FR) and enjoyment of food (CEBQ-EF), and children were weighed and measured. Despite differing preload conditions, children showed remarkable consistency of intake patterns across all five meals with day-to-day intra-class correlations in absolute and percentage intake of each food category ranging from .78 to .91. Higher CEBQ-SR was associated with lower mean intake of all food categories across all five meals, with the weakest association apparent for snack foods. Higher CEBQ-FR was associated with higher intake of white bread and fruits and vegetables, and higher CEBQ-EF was associated with greater intake of all categories, with the strongest association apparent for white bread. Analyses of intake of each food group as a percentage of total intake, treated here as an index of the child’s choice to consume relatively more or relatively less of each different food category when composing their total lunch-time meal, further suggested that children who were higher in CEBQ-SR ate relatively more snack foods and relatively less fruits and vegetables, while children with higher CEBQ-EF ate relatively less snack foods and relatively more white bread. Higher absolute intakes of white bread and snack foods were associated with higher BMI z score. CEBQ sub-scale associations with food intake variables were largely unchanged by controlling for daily metabolic needs. However, descriptive comparisons of lunch intakes with

  10. Lunch-time food choices in preschoolers: Relationships between absolute and relative intakes of different food categories, and appetitive characteristics and weight.

    Science.gov (United States)

    Carnell, S; Pryor, K; Mais, L A; Warkentin, S; Benson, L; Cheng, R

    2016-08-01

    Children's appetitive characteristics measured by parent-report questionnaires are reliably associated with body weight, as well as behavioral tests of appetite, but relatively little is known about relationships with food choice. As part of a larger preloading study, we served 4-5year olds from primary school classes five school lunches at which they were presented with the same standardized multi-item meal. Parents completed Child Eating Behavior Questionnaire (CEBQ) sub-scales assessing satiety responsiveness (CEBQ-SR), food responsiveness (CEBQ-FR) and enjoyment of food (CEBQ-EF), and children were weighed and measured. Despite differing preload conditions, children showed remarkable consistency of intake patterns across all five meals with day-to-day intra-class correlations in absolute and percentage intake of each food category ranging from 0.78 to 0.91. Higher CEBQ-SR was associated with lower mean intake of all food categories across all five meals, with the weakest association apparent for snack foods. Higher CEBQ-FR was associated with higher intake of white bread and fruits and vegetables, and higher CEBQ-EF was associated with greater intake of all categories, with the strongest association apparent for white bread. Analyses of intake of each food group as a percentage of total intake, treated here as an index of the child's choice to consume relatively more or relatively less of each different food category when composing their total lunch-time meal, further suggested that children who were higher in CEBQ-SR ate relatively more snack foods and relatively less fruits and vegetables, while children with higher CEBQ-EF ate relatively less snack foods and relatively more white bread. Higher absolute intakes of white bread and snack foods were associated with higher BMI z score. CEBQ sub-scale associations with food intake variables were largely unchanged by controlling for daily metabolic needs. However, descriptive comparisons of lunch intakes with

  11. High Molecular Weight Petrogenic and Pyrogenic Hydrocarbons in Aquatic Environments

    Science.gov (United States)

    Abrajano, T. A., Jr.; Yan, B.; O'Malley, V.

    2003-12-01

    Geochemistry is ultimately the study of sources, movement, and fate of chemicals in the geosphere at various spatial and temporal scales. Environmental organic geochemistry focuses such studies on organic compounds of toxicological and ecological concern (e.g., Schwarzenbach et al., 1993, 1998; Eganhouse, 1997). This field emphasizes not only those compounds with potential toxicological properties, but also the geological systems accessible to the biological receptors of those hazards. Hence, the examples presented in this chapter focus on hydrocarbons with known health and ecological concern in accessible shallow, primarily aquatic, environments.Modern society depends on oil for energy and a variety of other daily needs, with present mineral oil consumption throughout the 1990s exceeding 3×109 t yr-1 (NRC, 2002). In the USA, e.g., ˜40% of energy consumed and 97% of transportation fuels are derived from oil. In the process of extraction, refinement, transport, use, and waste production, a small but environmentally significant fraction of raw oil materials, processed products, and waste are released inadvertently or purposefully into the environment. Because their presence and concentration in the shallow environments are often the result of human activities, these organic materials are generally referred to as "environmental contaminants." Although such reference connotes some form of toxicological or ecological hazard, specific health or ecological effects of many organic "environmental contaminants" remain to be demonstrated. Some are, in fact, likely innocuous at the levels that they are found in many systems, and simply adds to the milieu of biogenic organic compounds that naturally cycle through the shallow environment. Indeed, virtually all compounds in crude oil and processed petroleum products have been introduced naturally to the shallow environments as oil and gas seepage for millions of years ( NRC, 2002). Even high molecular weight (HMW) polyaromatic

  12. A method for determining weights for excess relative risk and excess absolute risk when applied in the calculation of lifetime risk of cancer from radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, Linda [Federal Office for Radiation Protection, Department of Radiation Protection and Health, Oberschleissheim (Germany); University of Manchester, The Faculty of Medical and Human Sciences, Manchester (United Kingdom); Schneider, Uwe [University of Zurich, Vetsuisse Faculty, Zurich (Switzerland); Radiotherapy Hirslanden AG, Aarau (Switzerland)

    2013-03-15

    Radiation-related risks of cancer can be transported from one population to another population at risk, for the purpose of calculating lifetime risks from radiation exposure. Transfer via excess relative risks (ERR) or excess absolute risks (EAR) or a mixture of both (i.e., from the life span study (LSS) of Japanese atomic bomb survivors) has been done in the past based on qualitative weighting. Consequently, the values of the weights applied and the method of application of the weights (i.e., as additive or geometric weighted means) have varied both between reports produced at different times by the same regulatory body and also between reports produced at similar times by different regulatory bodies. Since the gender and age patterns are often markedly different between EAR and ERR models, it is useful to have an evidence-based method for determining the relative goodness of fit of such models to the data. This paper identifies a method, using Akaike model weights, which could aid expert judgment and be applied to help to achieve consistency of approach and quantitative evidence-based results in future health risk assessments. The results of applying this method to recent LSS cancer incidence models are that the relative EAR weighting by cancer solid cancer site, on a scale of 0-1, is zero for breast and colon, 0.02 for all solid, 0.03 for lung, 0.08 for liver, 0.15 for thyroid, 0.18 for bladder and 0.93 for stomach. The EAR weighting for female breast cancer increases from 0 to 0.3, if a generally observed change in the trend between female age-specific breast cancer incidence rates and attained age, associated with menopause, is accounted for in the EAR model. Application of this method to preferred models from a study of multi-model inference from many models fitted to the LSS leukemia mortality data, results in an EAR weighting of 0. From these results it can be seen that lifetime risk transfer is most highly weighted by EAR only for stomach cancer. However

  13. Rheological properties of poly (vinylpiyrrolidone) as a function of average molecular weight and its applications

    DEFF Research Database (Denmark)

    Marani, Debora; Sudireddy, Bhaskar Reddy; Kiebach, Ragnar

    characterized regarding their viscosimetric properties in ethanol. Average molecular weights (Mw, Mn, and Mz) have been determined by gel permeation chromatography (GPC), and then used in a numerical method to evaluate the viscosity average molecular weight (Mv) via the Mark-Houwink-Sakurada (MHS) equation...

  14. Loss of high-molecular-weight cytokeratin antigenicity in prostate tissue obtained by transurethral resections

    DEFF Research Database (Denmark)

    Multhaupt, H A; Fessler, J N; Warhol, M J

    2000-01-01

    OBJECTIVE: Staining of prostatic basal cells for the expression of high-molecular-weight cytokeratin has been suggested as a way of distinguishing benign from malignant prostate glands. We evaluated the utility of high-molecular-weight cytokeratin in the diagnosis of malignancy in prostate specim...

  15. Low molecular weight heparin versus unfractionated heparin in the initial treatment of venous thromboembolism

    NARCIS (Netherlands)

    Hettiarachchi, R. J.; Prins, M. H.; Lensing, A. W.; Buller, H. R.

    1998-01-01

    In this review, we analyze data from randomized trials in which low molecular weight heparin was compared with unfractionated heparin, both to estimate the treatment effect of low molecular weight heparin in the initial treatment of venous thromboembolism and to evaluate the effect of the varied

  16. Silica-reinforced natural rubber with epoxidized low molecular weight rubber as a compatibilizer

    NARCIS (Netherlands)

    Saramolee, P.; Sahakaro, Kannika; Lopattananon, N.; Dierkes, Wilma K.; Noordermeer, Jacobus W.M.

    2013-01-01

    This work investigates the effect of epoxidized low molecular weight natural rubber (ELMWNR) in silica-filled NR compounds on processing, mechanical and dynamic mechanical properties. The ELMWNRs with mol% epoxide groups varying from 0-50 and molecular weight in a range of 50,000-60,000 g/mol were

  17. Developer molecular size dependence of pattern formation of polymer type electron beam resists with various molecular weights

    Science.gov (United States)

    Takayama, Tomohiro; Asada, Hironori; Kishimura, Yukiko; Ochiai, Shunsuke; Hoshino, Ryoichi; Kawata, Atsushi

    2016-05-01

    The sensitivity and the resolution are affected by not only the nature of the resist such as a chemical structure and a molecular weight but also the developing process such as a developer molecular size. Exposure characteristics of positive-tone polymer resists having various molecular weights (Mw's) ranging from 60 k to 500 k are investigated using different ester solvents as a developer. The line-and-space (L/S) patterns are exposed by the electron beam writing system with an acceleration voltage of 50 kV and the samples are developed by amyl acetate, hexyl acetate and heptyl acetate. The pattern shape becomes better and the surface of the resist also becomes smoother with increasing developer molecular size, though the exposure dose required for the formation of the L/S pattern increases. The dose margin of pattern formation is also wider in all the resists having the different molecular weights. The dissolution in the unexposed portions of the 60k-Mw resist for heptyl acetate is reduced significantly compared with those for amyl acetate and hexyl acetate. The improvement of the pattern shape and the increasing of dose margin are remarkable in the low molecular weight resist. The 3σ of line width roughness tends to be smaller in the higher molecular weight resist and with the larger molecular size developer. Exposure experiment of the 35 nm pitch pattern using the 500k-Mw resist developed at the room temperature is presented.

  18. Calculation of molecular weights of humic substances from colligative data: Application to aquatic humus and its molecular size fractions

    Science.gov (United States)

    Reuter, J. H.; Perdue, E. M.

    1981-11-01

    A rigorous mathematical expression for the dependence of colligative properties on acid dissociation of water soluble humic substances is presented. New data for number average molecular weights of a river derived humic material and its gel permeation Chromatographic fractions are compared with M¯n values obtained by a reevaluation of previously published experimental observations on soil and water fulvic acids. The results reveal a remarkable similarity of fulvic acids from widely different sources with respect to number-average molecular weight.

  19. Immunochemical identity of the high and low molecular weight forms of Galapagos marine iguana hemoglobin.

    Science.gov (United States)

    Higgins, P J

    1978-01-01

    1. Two forms of Galapagos marine iguana methemoglobin, with molecular weights of 140,000 and 70,000 daltons, were identified in iguana RBC lysates by Sephadex G-200 molecular sieve fractionation. 2. The 140,000 dalton ferric hemoglobin was isolated by DEAE-Sephadex A-50 ion-exchange chromatography and found to be pure by electrophoretic and immunological criteria. 3. Immunochemical analyses revealed the high and low molecular weight hemoglobins to be antigenically identical.

  20. Correlation between Microstructure and Rheological Properties of Broad Molecular Weight Distribution High Density Polyethylenes

    Directory of Open Access Journals (Sweden)

    Mohammad Javad Shirkavand

    2015-03-01

    Full Text Available In this article, the correlation between molecular microstructure and rheological behavior for three different grades of high density polyethylene with broad molecular weight distribution have been investigated. Structural parameters such as Mn, Mw, Mz, molecular weight distribution (MWD and branching index were characterized by high temperature Gel Permeation Chromatography (GPC test. GPC results showed that BL4 and EX3 have bigger weight average molecular weight and narrower molecular weight distribution, respectively. Furthermore,it was found from GPC results that all three HDPE has a broad MWD and EX3 has more short chain branches than two other samples. Rheological characterization was done in a Mechanical Compact Rheometer (MCR in rotational and dynamic modes at both linear and nonlinear viscoelastic region. From rheological characterization the zero shear viscosity (η0, relaxation time and relaxation time distribution, stress relaxation modulus and damping factor were obtained and by utilizing relaxation time spectrum function (h(τ, molecular weight distribution was calculated for each sample and compared with GPC results. The relationship between zero shear viscosity with molecular weight and MWD at 180 ºC obtained. After calculating molecular weight distribution function and average molecular weights using different mixing parameters (β, by choosing β=0.73, a good correlation between molecular parameters obtained from rheological data with those of GPC results was obtained. After calculating stress relaxation modulus and consequently damping factor for each sample, comparing to Doi-Edwards model, it was found that the damping function type C is an appropriate damping function type for selected polyethylenes.

  1. Low molecular weight organic acids in root exudates and cadmium ...

    African Journals Online (AJOL)

    ajl yemi

    2011-11-28

    –234. Cieslinski G, Van Rees KCJ, Szmigielska AM, Krishnamurti GSR,. Huang PM (1998). Lowmolecular-weight organic acids in rhizosphere soils of durum wheat and their effect on cadmium bioaccumulation. Plant Soil, 203: ...

  2. Molecular weight kinetics and chain scission models for dextran polymers during ultrasonic degradation.

    Science.gov (United States)

    Pu, Yuanyuan; Zou, Qingsong; Hou, Dianzhi; Zhang, Yiping; Chen, Shan

    2017-01-20

    Ultrasonic degradation of six dextran samples with different initial molecular weights (IMW) has been performed to investigate the degradation behavior and chain scission mechanism of dextrans. The weight-average molecular weight (Mw) and polydispersity index (D value) were monitored by High Performance Gel Permeation Chromatography (HPGPC). Results showed that Mw and D value decreased with increasing ultrasonic time, resulting in a more homologous dextran solution with lower molecular weight. A significant degradation occurred in dextrans with higher IMW, particularly at the initial stage of the ultrasonic treatment. The Malhotra model was found to well describe the molecular weight kinetics for all dextran samples. Experimental data was fitted into two chain scission models to study dextran chain scission mechanism and the model performance was compared. Results indicated that the midpoint scission model agreed well with experimental results, with a linear regression factor of R 2 >0.99. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. How Does the Preparation of Rye Porridge Affect Molecular Weight Distribution of Extractable Dietary Fibers?

    Directory of Open Access Journals (Sweden)

    Roger Andersson

    2011-05-01

    Full Text Available Extractable dietary fiber (DF plays an important role in nutrition. This study on porridge making with whole grain rye investigated the effect of rest time of flour slurries at room temperature before cooking and amount of flour and salt in the recipe on the content of DF components and molecular weight distribution of extractable fructan, mixed linkage (1→3(1→4-β-D-glucan (β-glucan and arabinoxylan (AX in the porridge. The content of total DF was increased (from about 20% to 23% of dry matter during porridge making due to formation of insoluble resistant starch. A small but significant increase in the extractability of β-glucan (P = 0.016 and AX (P = 0.002 due to rest time was also noted. The molecular weight of extractable fructan and AX remained stable during porridge making. However, incubation of the rye flour slurries at increased temperature resulted in a significant decrease in extractable AX molecular weight. The molecular weight of extractable β-glucan decreased greatly during a rest time before cooking, most likely by the action of endogenous enzymes. The amount of salt and flour used in the recipe had small but significant effects on the molecular weight of β-glucan. These results show that whole grain rye porridge made without a rest time before cooking contains extractable DF components maintaining high molecular weights. High molecular weight is most likely of nutritional importance.

  4. Temperature and molecular-weight dependences of acoustic behaviors of polystyrene studied using Brillouin spectroscopy

    Science.gov (United States)

    Oh, Soo Han; Lee, Byoung Wan; Ko, Jae-Hyeon; Lee, Hyeonju; Park, Jaehoon; Ko, Young Ho; Kim, Kwang Joo

    2017-04-01

    The acoustic properties of three polystyrene polymers with different molecular weights were investigated as a function of temperature by using Brillouin light scattering. The longitudinal sound velocity showed a change in the slope, which depended on the molecular weight, at the glass transition temperature. The absorption coefficient exhibited a maximum above the glass transition temperature, and the maximum temperature became higher as the molecular weight was increased. Comparison with previous acoustic studies on polystyrene indicate that a substantial frequency dispersion caused by strong coupling between the longitudinal acoustic waves and the segmental motions exists in the high-temperature range.

  5. Determination of Viscosity-Average Molecular Weight of Chitosan using Intrinsic Viscosity Measurement

    International Nuclear Information System (INIS)

    Norzita Yacob; Norhashidah Talip; Maznah Mahmud

    2011-01-01

    Molecular weight of chitosan can be determined by different techniques such as Gel Permeation Chromatography (GPC), Static Light Scattering (SLS) and intrinsic viscosity measurement. Determination of molecular weight by intrinsic viscosity measurement is a simple method for characterization of chitosan. Different concentrations of chitosan were prepared and measurement was done at room temperature. The flow time data was used to calculate the intrinsic viscosity by extrapolating the reduced viscosity to zero concentration. The value of intrinsic viscosity was then recalculated into the viscosity-average molecular weight using Mark-Houwink equation. (author)

  6. Role of Molecular Weight Distribution on Charge Transport in Semiconducting Polymers

    KAUST Repository

    Himmelberger, Scott

    2014-10-28

    © 2014 American Chemical Society. Model semiconducting polymer blends of well-controlled molecular weight distributions are fabricated and demonstrated to be a simple method to control intermolecular disorder without affecting intramolecular order or degree of aggregation. Mobility measurements exhibit that even small amounts of low molecular weight material are detrimental to charge transport. Trends in charge carrier mobility can be reproduced by a simple analytical model which indicates that carriers have no preference for high or low molecular weight chains and that charge transport is limited by interchain hopping. These results quantify the role of long polymer tie-chains and demonstrate the need for controlled polydispersity for achieving high carrier mobilities.

  7. Low molecular weight chitosan–insulin polyelectrolyte complex: characterization and stability studies

    OpenAIRE

    Al-Kurdi, Zakieh; Chowdhry, Babur Z.; Leharne, Stephen A.; Omari, Mahmoud; Badwan, Adnan

    2015-01-01

    The aim of the work reported herein was to investigate the effect of various low molecular weight chitosans (LMWCs) on the stability of insulin using USP HPLC methods. Insulin was found to be stable in a polyelectrolyte complex (PEC) consisting of insulin and LMWC in the presence of a Tris-buffer at pH 6.5. In the presence of LMWC, the stability of insulin increased with decreasing molecular weight of LMWC; 13 kDa LMWC was the most efficient molecular weight for enhancing the physical and che...

  8. Absolute Summ

    Science.gov (United States)

    Phillips, Alfred, Jr.

    Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

  9. Body weight, hemoglobin, and absolute neutrophil count in patients with advanced-stage epithelial ovarian cancer who received chemotherapy: A single-center study

    Science.gov (United States)

    Gunawan, Y.; Winarto, H.

    2017-08-01

    The side effects of chemotherapy, a treatment modality of ovarian cancer, can disrupt overall treatment. To date, the clinical and laboratory profiles of ovarian cancer patients during chemotherapy have not been investigated. This study aimed to elucidate the clinical and laboratory profiles of patients with advanced-stage epithelial ovarian cancer who received chemotherapy in Dr. Cipto Mangunkusumo Hospital, including body mass index (BMI), hemoglobin (Hb), and absolute neutrophil count (ANC). To generate these clinical and laboratory profiles, we collected secondary data from the medical records of advanced-stage epithelial ovarian cancer patients who received six cycles of carboplatin and paclitaxel chemotherapy. We enrolled 23 patients with advanced-stage epithelial ovarian cancer patients who received six cycles of chemotherapy. Mean patient BMI before and after chemotherapy was 22.86 kg/m2 and 21.78 kg/m2, respectively. Hb levels before chemotherapy were 8-13 g/dl, with Hb Hb ≥ 10 g/dl in 22 patients (95.65%). Mean ANC was 5845.6 ± 3325.0. An average of 24.65% of patients experienced anemia after each cycle of chemotherapy. Mean ANC before chemotherapy was 3.5582 ± 3.3250. An average of 26.81% of patients had ANC Hb ≥ 10 g/dl before chemotherapy, 16 (72.72%) experienced a decrease in ANC during chemotherapy. Of the 20 patients (60.87%) with normal BMI or higher, 14 experienced a decrease in ANC during chemotherapy. The mean patient body weight decreased after six cycles of chemotherapy. Hb and ANC were persistently decreased in approximately a quarter of the 23 subjects. The decrease in ANC was not influenced by initial Hb and BMI.

  10. Attempts to Improve Absolute Quantification of Cerebral Blood Flow in Dynamic Susceptibility Contrast Magnetic Resonance Imaging: A Simplified T1-Weighted Steady-State Cerebral Blood Volume Approach

    International Nuclear Information System (INIS)

    Wirestam, R.; Knutsson, L.; Risberg, J.; Boerjesson, S.; Larsson, E.M.; Gustafson, L.; Passant, U.; Staahlberg, F.

    2007-01-01

    Background: Attempts to retrieve absolute values of cerebral blood flow (CBF) by dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) have typically resulted in overestimations. Purpose: To improve DSC-MRI CBF estimates by calibrating the DSC-MRI-based cerebral blood volume (CBV) with a corresponding T1-weighted (T1W) steady-state (ss) CBV estimate. Material and Methods: 17 volunteers were investigated by DSC-MRI and 133Xe SPECT. Steady-state CBV calculation, assuming no water exchange, was accomplished using signal values from blood and tissue, before and after contrast agent, obtained by T1W spin-echo imaging. Using steady-state and DSC-MRI CBV estimates, a calibration factor K = CBV(ss)/CBV(DSC) was obtained for each individual. Average whole-brain CBF(DSC) was calculated, and the corrected MRI-based CBF estimate was given by CBF(ss) = KxCBF(DSC). Results: Average whole-brain SPECT CBF was 40.1±6.9 ml/min 100 g, while the corresponding uncorrected DSC-MRI-based value was 69.2±13.8 ml/mi 100 g. After correction with the calibration factor, a CBF(ss) of 42.7±14.0 ml/min 100 g was obtained. The linear fit to CBF(ss)-versus-CBF(SPECT) data was close to proportionality (R 0.52). Conclusion: Calibration by steady-state CBV reduced the population average CBF to a reasonable level, and a modest linear correlation with the reference 133Xe SPECT technique was observed. Possible explanations for the limited accuracy are, for example, large-vessel partial-volume effects, low post-contrast signal enhancement in T1W images, and water-exchange effects

  11. High Molecular Weight Forms of Mammalian Respiratory Chain Complex II

    Czech Academy of Sciences Publication Activity Database

    Kovářová, Nikola; Mráček, Tomáš; Nůsková, Hana; Holzerová, Eliška; Vrbacký, Marek; Pecina, Petr; Hejzlarová, Kateřina; Klučková, Katarína; Rohlena, Jakub; Neužil, Jiří; Houštěk, Josef

    2013-01-01

    Roč. 8, č. 8 (2013), e71869 E-ISSN 1932-6203 R&D Projects: GA ČR(CZ) GPP303/10/P227; GA MŠk(CZ) LL1204; GA MZd(CZ) NT12370; GA ČR(CZ) GAP301/10/1937 Institutional research plan: CEZ:AV0Z50520701 Institutional support: RVO:67985823 Keywords : supercomplexes * high molecular weihgt forms of complex II * native electrophoretic systems Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.534, year: 2013

  12. Modeling the relationship between body weight and energy intake: a molecular diffusion-based approach.

    Science.gov (United States)

    Gong, Zhejun; Gong, Zhefeng

    2012-06-29

    Body weight is at least partly controlled by the choices made by a human in response to external stimuli. Changes in body weight are mainly caused by energy intake. By analyzing the mechanisms involved in food intake, we considered that molecular diffusion plays an important role in body weight changes. We propose a model based on Fick's second law of diffusion to simulate the relationship between energy intake and body weight. This model was applied to food intake and body weight data recorded in humans; the model showed a good fit to the experimental data. This model was also effective in predicting future body weight. In conclusion, this model based on molecular diffusion provides a new insight into the body weight mechanisms. This article was reviewed by Dr. Cabral Balreira (nominated by Dr. Peter Olofsson), Prof. Yang Kuang and Dr. Chao Chen.

  13. Research Article Allelic Variation of High Molecular Weight Glutenin ...

    Indian Academy of Sciences (India)

    Sky123.Org

    HMW-GS may be an important source of genes for quality improvement, uncovering the composition of HMW-GS in different wheat varieties is essential for molecular design breeding in controlling wheat end-use quality. In Hebei Province, the study of genetic improvement of wheat quality has begun since 1980's, and some ...

  14. Low molecular weight organic acids in root exudates and cadmium ...

    African Journals Online (AJOL)

    The S. nigrum with higher concentrations of LMWOA in roots exudation accumulated more Cd in the plants. The results indicated tha LMWOA secretion by S. nigrum root, especially in Cd-contaminated soils, was likely to be an important role in Cd hyperaccumulation. Key words: Cadmium, Solanum nigrum L., low molecular ...

  15. Enhancing Accuracy in Molecular Weight Determination of Highly Heterogeneously Glycosylated Proteins by Native Tandem Mass Spectrometry

    NARCIS (Netherlands)

    Wang, Guanbo; de Jong, Rob N; van den Bremer, Ewald T J; Parren, Paul W H I; Heck, Albert J R

    2017-01-01

    The determination of molecular weights (MWs) of heavily glycosylated proteins is seriously hampered by the physicochemical characteristics and heterogeneity of the attached carbohydrates. Glycosylation impacts protein migration during sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis

  16. Effect of protein molecular weight on the mass transfer in protein mixing

    Science.gov (United States)

    Asad, Ahmed; Chai, Chuan; Wu, JiangTao

    2012-03-01

    The mixing of protein solutions with that of precipitating agents is very important in protein crystallization experiments. In this work, the interferometry images were recorded during the mixing of two proteins with different molecular weights: lysozyme of ˜14.6 kDa, trypsin of ˜23.3 kDa and pepsin of ˜34.8 kDa were placed in a Mach-Zehnder interferometer. The protein molecular weight dependence on the competition of the transport process and kinetics at the interface was studied. The concentration profiles of protein solutions were calculated to analyze the mass transfer during the mixing process. It was observed that the mass transfer process is more efficient during the mixing of proteins with higher molecular weights. In addition, the more rapid concentration changes above the interface suggest that convection may dominate the diffusion. The phenomenon of convection is higher in the protein solutions with higher molecular weight.

  17. Interactions of mercury with different molecular weight fractions of humic substances in aquatic systems.

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Yao, K.M.; Chennuri, K.; Vudamala, K.; Babu, P.V.R.

    Interactions of mercury (Hg) with different molecular weight fractions of humic substances (HS) play an important role in controlling distribution, diffusion, speciation, and bioavailability of Hg in natural systems. This study suggests that Hg...

  18. Enzymatic degradation of poly(butylene succinate) with different molecular weights by cutinase.

    Science.gov (United States)

    Pan, Wenjing; Bai, Zhenhui; Su, Tingting; Wang, Zhanyong

    2018-05-01

    Poly(butylene succinate) (PBS) films with different molecular weights were enzymatically degraded by cutinase. Changes in the properties of the films before and after enzymatic degradation were studied through scanning electron microscopy, differential scanning calorimetry, thermogravimetry, X-ray powder diffraction, proton nuclear magnetic resonance, and gel-permeation chromatography analysis. The weight loss of the films initially decreased and then increased with increasing molecular weight. Crystallinity was inversely proportional to weight loss and tended to decrease with prolonged degradation time. Crystalline and amorphous regions were simultaneously degraded. The thermal stability of PBS films decreased after enzymatic degradation. PBS was the main component of the enzymatically degraded polymers. The molecular weights of the films did not considerably change before and after degradation by cutinase. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Molecular dynamics and density functional theory simulations of matrix deposition. II. Absolute site structure assignment for porphyrin in xenon.

    Science.gov (United States)

    Kyrychenko, Alexander; Gorski, Alexander; Waluk, Jacek

    2004-12-15

    Molecular dynamics calculations reveal that the main trapping site for porphyrin embedded in a xenon matrix corresponds to a hexagonal cavity formed after removal of seven host atoms. Tautomerization involving two inner hydrogen atoms leads to two trans forms that interact differently with the matrix cage. Therefore, both electronic and infrared spectra are split into doublets. Comparison of the experimentally observed splitting patterns with the results of density functional theory calculations that explicitly include the nearest xenon atoms allows assigning each spectral feature to one of two different configurations of the chromophore inside the xenon cavity. The main factor responsible for the splittings is a distortion of the molecular skeleton from a squarelike towards rectangular geometry. (c) 2004 American Institute of Physics

  20. Influences of gamma irradiation treatment on the molecular weight of chitosan

    International Nuclear Information System (INIS)

    Luu Thi Tho; Nguyen Viet Thong; Tran Minh Quynh; Vu Thi Hong Khanh

    2013-01-01

    Effects of gamma radiation on molecular properties of shrimp and squid chitosan (MTV, Vietnam) have been studied with three kind chitosan that having degree of deacetylation 75% and different molecular molecular weight of 69, 187 and 345 kDa, Chitosan samples were irradiated at the same dose rate of 4.3 kGy per hour with various radiation dose of 25, 50, 75, 100, 200 and 500 kGy. The viscosity average molecular weight and degree of deacetylation (DD) of chitosan before and after irradiation have been investigated via their intrinsic viscosity and Furrier transform infra-red (FT-IR). The data revealed the chitosan backbone chains has been degraded by gamma radiation, resulting in the smaller fragments with reduced molecular weight to 3000 Da, whereas their DD have not much changed. (author)

  1. Nitrogen mineralization in a simulated rhizosphere as influenced by low molecular weight organic substances

    OpenAIRE

    Begum, Shamim Ara; Kader, MD Abdul; Sleutel, Steven; De Neve, Stefaan

    2012-01-01

    Rhizodeposits consist of over 200 organic compounds, mainly low-molecular-weight organic substances (LMWOS) such as amino acids (AA), carbohydrates (CH) and carboxylic acids (CA), lipids and phenols. Those LMWOS influence nutrient turnover, particularly N turnover. However, the exact influence of these organic substances on nitrogen mineralization is yet unknown. Therefore, the stimulatory effects of low molecular weight organic substances on nitrogen mineralization in the rhizosphere of a si...

  2. A Multidisciplinary Study of Ciguatoxin and Related Low Molecular Weight Toxins from Marine Source

    Science.gov (United States)

    1986-08-01

    Prorocentrum lima . Bull. Jpns. Soc. Sci. Fish. 4a:69-72, 1982. 11. Banner, A.H., S. Sasaki, P. Helfrich, C.B. Nender and P.J. Scheuer. Bioassay of...Ln ADa I iic Ek A MULTIDISCIPLINARY STUDY OF CIGUATOXIN AND SRELATED LOW MOLECULAR WEIGHT TOXINS FROM MARINE SOURCES ANNUAL REPORT LESLIE E. BAILEY...MOLECULAR WEIGHT TOXINS FROM MARINE SOURCES ANNUAL REPORT LESLIE E. BAILEY YOSHITSUGI HOKAMA JAMES T. MIYAHARA PAUL J. SCHEUER AUGUST 1986 Supported by

  3. Control of molecular weight distribution in synthesis of poly(2-hydroxyethyl methacrylate) using ultrasonic irradiation.

    Science.gov (United States)

    Kubo, Masaki; Kondo, Takayuki; Matsui, Hideki; Shibasaki-Kitakawa, Naomi; Yonemoto, Toshikuni

    2018-01-01

    Poly(2-hydroxyethyl methacrylate) (PHEMA) was synthesized using ultrasonic irradiation without any chemical initiator. The effect of the ultrasonic power intensity on the time course of the conversion to polymer, the number average molecular weight, and the polydispersity were investigated in order to synthesize a polymer with a low molecular weight distribution (i.e., low polydispersity). The conversion to polymer increased with time. A higher ultrasonic power intensity resulted in a faster reaction rate. The number average molecular weight increased during the early stage of the reaction and then gradually decreased with time. A higher ultrasonic intensity resulted in a faster degradation rate of the polymer. The polydispersity decreased with time. This was because the degradation rate of a polymer with a higher molecular weight was faster than that of a polymer with a lower molecular weight. A polydispersity below 1.3 was obtained under ultrasonic irradiation. By changing the ultrasonic power intensity during the reaction, the number average molecular weight can be controlled while maintaining low polydispersity. When the ultrasonic irradiation was halted, the reactions stopped and the number average molecular weight and polydispersity did not change. On the basis of the experimental results, a kinetic model for synthesis of PHEMA under ultrasonic irradiation was constructed considering both polymerization and polymer degradation. The kinetic model was in good agreement with the experimental results for the time courses of the conversion to polymer, the number average molecular weight, and the polydispersity for various ultrasonic power intensities. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. High and low molecular weight hyaluronic acid differentially influence macrophage activation

    Science.gov (United States)

    Rayahin, Jamie E.; Buhrman, Jason S.; Zhang, Yu; Koh, Timothy J.; Gemeinhart, Richard A.

    2015-01-01

    Macrophages exhibit phenotypic diversity permitting wide-ranging roles in maintaining physiologic homeostasis. Hyaluronic acid, a major glycosaminoglycan of the extracellular matrix, has been shown to have differential signaling based on its molecular weight. With this in mind, the main objective of this study was to elucidate the role of hyaluronic acid molecular weight on macrophage activation and reprogramming. Changes in macrophage activation were assessed by activation state selective marker measurement, specifically quantitative real time polymerase chain reaction, and cytokine enzyme-linked immunoassays, after macrophage treatment with differing molecular weights of hyaluronic acid under four conditions: the resting state, concurrent with classical activation, and following inflammation involving either classically or alternatively activated macrophages. Regardless of initial polarization state, low molecular weight hyaluronic acid induced a classically activated-like state, confirmed by up-regulation of pro-inflammatory genes, including nos2, tnf, il12b, and cd80, and enhanced secretion of nitric oxide and TNF-α. High molecular weight hyaluronic acid promoted an alternatively activated-like state, confirmed by up regulation of pro-resolving gene transcription, including arg1, il10, and mrc1, and enhanced arginase activity. Overall, our observations suggest that macrophages undergo phenotypic changes dependent on molecular weight of hyaluronan that correspond to either (1) pro-inflammatory response for low molecular weight HA or (2) pro-resolving response for high molecular weight HA. These observations bring significant further understanding of the influence of extracellular matrix polymers, hyaluronic acid in particular, on regulating the inflammatory response of macrophages. This knowledge can be used to guide the design of HA-containing biomaterials to better utilize the natural response to HAs. PMID:26280020

  5. Molecular weight effects on the miscibility behavior of dextran and maltodextrin with poly(vinylpyrrolidone).

    Science.gov (United States)

    Van Eerdenbrugh, Bernard; Taylor, Lynne S

    2012-10-01

    To characterize and interpret the miscibility of dextran and maltodextrin with poly(vinylpyrrolidone) (DEX-PVP) as a function of polymer molecular weights. Blend miscibility was studied using 4 different molecular weight (MW) grades of DEX combined with 5 MW grades of PVP, over a broad compositional range. Miscibility was evaluated by inspection of glass transition events measured by differential scanning calorimetry (DSC). Fourier transform mid-infrared spectroscopy (FTIR), combined with curve fitting, was performed to characterize the extent of hydrogen bonding. The observed miscibility behavior was further interpreted in terms of mixing thermodynamics. Miscibility of the blends ranged from fully miscible to completely immiscible with multiple partially miscible systems observed. Increasing polymer molecular weight decreased miscibility. For the lowest DEX grade, hydrogen bonding was independent of PVP MW, as expected since all systems were completely miscible. Higher molecular weights of DEX resulted in reduced intermolecular hydrogen bonding and decreased miscibility, increasingly so for higher MW PVP grades. Evaluation of the mixing thermodynamics supported these findings. With higher combined molecular weights of DEX-PVP blends, phase behavior evolves from completely miscible to virtually immiscible. Concurrently, DEX-PVP hydrogen bonding decreases. From a thermodynamic perspective, the combinatorial mixing entropy was observed to decrease as the molecular weight of the polymers increased, providing a reduced counterbalance to the unfavorable mixing enthalpy thought to accompany this polymer combination.

  6. Improving the accuracy of hyaluronic acid molecular weight estimation by conventional size exclusion chromatography.

    Science.gov (United States)

    Shanmuga Doss, Sreeja; Bhatt, Nirav Pravinbhai; Jayaraman, Guhan

    2017-08-15

    There is an unreasonably high variation in the literature reports on molecular weight of hyaluronic acid (HA) estimated using conventional size exclusion chromatography (SEC). This variation is most likely due to errors in estimation. Working with commercially available HA molecular weight standards, this work examines the extent of error in molecular weight estimation due to two factors: use of non-HA based calibration and concentration of sample injected into the SEC column. We develop a multivariate regression correlation to correct for concentration effect. Our analysis showed that, SEC calibration based on non-HA standards like polyethylene oxide and pullulan led to approximately 2 and 10 times overestimation, respectively, when compared to HA-based calibration. Further, we found that injected sample concentration has an effect on molecular weight estimation. Even at 1g/l injected sample concentration, HA molecular weight standards of 0.7 and 1.64MDa showed appreciable underestimation of 11-24%. The multivariate correlation developed was found to reduce error in estimations at 1g/l to estimate the molecular weight of HA produced by a recombinant Lactococcus lactis fermentation. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Developing a Macroscopic Mechanistic Model for Low Molecular Weight Diffusion through Polymers in the Rubbery State

    DEFF Research Database (Denmark)

    Martinez-Lopez, Brais; Huguet, P.; Gontard, N.

    2016-01-01

    Raman microspectroscopy was used to determine the Fickian diffusivity of two families of low molecular weight molecules through amorphous polystyrene in the rubbery state. Different effects of the temperature on diffusivity for each of the families suggested that molecular mobility is controlled ...

  8. Use of Kinematic Viscosity Data for the Evaluation of the Molecular Weight of Petroleum Oils

    Science.gov (United States)

    Maroto, J. A.; Quesada-Perez, M.; Ortiz-Hernandez, A. J.

    2010-01-01

    A new laboratory procedure for the evaluation of the mean molecular weight (mean relative molecular mass) of petroleum oils with high accuracy is described. The density and dynamic viscosity of three commercial petroleum oils are measured at different temperatures. These experimental data are used to calculate the kinematic viscosity as a function…

  9. Study of effect of gamma radiation on molecular weight and mechanical properties of PHB and PHNV

    International Nuclear Information System (INIS)

    Fechine, Guilhermino J.M.; Terence, Mauro C.; Rabello, M.S.; Willen, Renate M.R.

    2011-01-01

    The effect of gamma radiation on molecular weight and mechanical properties (tensile and flexural) of PHB and PHBV samples was investigated. The values of stress and strain at the break point for both mechanical properties indicated that scission molecular reactions were predominant in PHB and PHBV samples submitted to gamma radiation. These results were confirmed by Size Exclusion Chromatography (SEC) analysis. (author)

  10. Molecular cloning, nucleotide sequence, and characterization of a 40,000-molecular-weight lipoprotein of Haemophilus somnus.

    OpenAIRE

    Theisen, M; Rioux, C R; Potter, A A

    1992-01-01

    A gene of Haemophilus somnus encoding the major 40,000-molecular-weight antigen (LppA) was cloned on a 2-kb Sau3AI fragment. The nucleotide sequence of the entire DNA insert was determined. One open reading frame, encoding a 247-residue polypeptide with a calculated molecular weight of 27,072, was identified. This reading frame was confirmed by sequencing the fusion joint of two independent IppA::TnphoA gene fusions. The 21 amino-terminal amino acids of the deduced polypeptide showed strong s...

  11. The distribution of 14C-chitosan by different molecular weight in mice

    International Nuclear Information System (INIS)

    Kim, Kwang Yoon; Kim, Young Ho; Bom, Hee Seung; Kim, Ji Yeul; Kim, Hee Kyung; Roh, Young Bok; Nishimura, Yoshikazu

    1998-01-01

    Chitosan is a nontoxic natural chealtor which was made by chitin, and reduced a contamination of radiostrontium in animals. In this experiment, a different molecular weight of C-14 chitosan was intravenously administered to mice, and then the distribution of C-14 chitosan in the body was observed. Male mice (8 to 10 weeks, body weight of 30 to 35g) of ICR strain were used. C-14 chitosan, mice was sacrificed at the 6th hour, 1st, 3rd, 5th, and 7th day. Beta radioactivities in the blood, liver, kidney, liver, muscle, testis, and urine was measured using a liquid scintillation analyzer. Most of the C-14 chitosan was excreted through urine within 6 hours. Biodistribution of C-14 chitosan was similar despite the difference of molecular weight. Higher distributions of radioactivities were found in the liver, kidney, spleen. The relative concentration in tissue increased for the 6 hours and then decreased. In conclusion, most of C-14 chitosan was excreted through urine despite the difference of molecular weight. and, low molecular weight of C-14 chitosan showed higher distribution than high molecular weight of C-14 chitosan in tissues

  12. Profiling of the Molecular Weight and Structural Isomer Abundance of Macroalgae-Derived Phlorotannins

    Science.gov (United States)

    Heffernan, Natalie; Brunton, Nigel P.; FitzGerald, Richard J.; Smyth, Thomas J.

    2015-01-01

    Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene) unique to macroalgae. These phenolic compounds are integral structural components of the cell wall in brown algae, but also play many secondary ecological roles such as protection from UV radiation and defense against grazing. This study employed Ultra Performance Liquid Chromatography (UPLC) with tandem mass spectrometry to investigate isomeric complexity and observed differences in phlorotannins derived from macroalgae harvested off the Irish coast (Fucus serratus, Fucus vesiculosus, Himanthalia elongata and Cystoseira nodicaulis). Antioxidant activity and total phenolic content assays were used as an index for producing phlorotannin fractions, enriched using molecular weight cut-off dialysis with subsequent flash chromatography to profile phlorotannin isomers in these macroalgae. These fractions were profiled using UPLC-MS with multiple reaction monitoring (MRM) and the level of isomerization for specific molecular weight phlorotannins between 3 and 16 monomers were determined. The majority of the low molecular weight (LMW) phlorotannins were found to have a molecular weight range equivalent to 4–12 monomers of phloroglucinol. The level of isomerization within the individual macroalgal species differed, resulting in substantially different numbers of phlorotannin isomers for particular molecular weights. F. vesiculosus had the highest number of isomers of 61 at one specific molecular mass, corresponding to 12 phloroglucinol units (PGUs). These results highlight the complex nature of these extracts and emphasize the challenges involved in structural elucidation of these compounds. PMID:25603345

  13. Profiling of the Molecular Weight and Structural Isomer Abundance of Macroalgae-Derived Phlorotannins

    Directory of Open Access Journals (Sweden)

    Natalie Heffernan

    2015-01-01

    Full Text Available Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene unique to macroalgae. These phenolic compounds are integral structural components of the cell wall in brown algae, but also play many secondary ecological roles such as protection from UV radiation and defense against grazing. This study employed Ultra Performance Liquid Chromatography (UPLC with tandem mass spectrometry to investigate isomeric complexity and observed differences in phlorotannins derived from macroalgae harvested off the Irish coast (Fucus serratus, Fucus vesiculosus, Himanthalia elongata and Cystoseira nodicaulis. Antioxidant activity and total phenolic content assays were used as an index for producing phlorotannin fractions, enriched using molecular weight cut-off dialysis with subsequent flash chromatography to profile phlorotannin isomers in these macroalgae. These fractions were profiled using UPLC-MS with multiple reaction monitoring (MRM and the level of isomerization for specific molecular weight phlorotannins between 3 and 16 monomers were determined. The majority of the low molecular weight (LMW phlorotannins were found to have a molecular weight range equivalent to 4–12 monomers of phloroglucinol. The level of isomerization within the individual macroalgal species differed, resulting in substantially different numbers of phlorotannin isomers for particular molecular weights. F. vesiculosus had the highest number of isomers of 61 at one specific molecular mass, corresponding to 12 phloroglucinol units (PGUs. These results highlight the complex nature of these extracts and emphasize the challenges involved in structural elucidation of these compounds.

  14. Molecular weight changes induced in an anionic polydimethylsiloxane by gamma irradiation in vacuum

    International Nuclear Information System (INIS)

    Satti, Angel J.; Andreucetti, Noemi A.; Ciolino, Andres E.; Vitale, Cristian; Sarmoria, Claudia; Valles, Enrique M.

    2010-01-01

    An anionic almost monodisperse linear polydimethylsiloxane (PDMS) was subjected to gamma irradiation under vacuum at room temperature. The molecular weight changes induced by the radiation process have been investigated using size exclusion chromatography (SEC) with refraction index (RI) and multi angle laser light scattering (MALLS) detectors, to obtain the number and weight average molecular weights of the irradiated samples. The analysis of the data indicates that crosslinking reactions predominated over scission reactions. The results obtained by an SEC-RI have confirmed the presence of small, but measurable amounts of scission. A previously developed mathematical model of the irradiation process that accounts for simultaneous scission and crosslinking and allows for both H- and Y-crosslinks, fitted well the measured molecular weight data. This prediction is in accordance with the experimental data obtained by 29 Si-Nuclear Magnetic Resonance spectroscopy (NMR) and previously reported data for commercial linear PDMS ().

  15. Elevated levels of high-molecular-weight adiponectin in type 1 diabetes

    DEFF Research Database (Denmark)

    Leth, H.; Andersen, K.K.; Frystyk, J.

    2008-01-01

    BACKGROUND: Several studies have shown that type 1 diabetic patients have elevated total levels of the adipocyte-derived adipocytokine adiponectin. However, adiponectin circulates in three different subforms, and the high-molecular-weight (HMW) subform is believed to be the primary biologically...... active form. The effects of the medium-molecular-weight (MMW) subform and the low-molecular-weight (LMW) subform are still unresolved. PURPOSE: The objective of the study was to investigate the distribution of the three molecular subforms of adiponectin in well-characterized groups of type 1 diabetics...... with varying degrees of nephropathy as well as in healthy control subjects. STUDY POPULATION: Two hundred seven individuals were included: 58 type 1 diabetics with normoalbuminuria, 46 with microalbuminuria, 46 with macroalbuminuria, and 57 matched controls. METHODS: The HMW, MMW, and LMW subforms were...

  16. Low molecular weight squash trypsin inhibitors from Sechium edule seeds.

    Science.gov (United States)

    Laure, Hélen J; Faça, Vítor M; Izumi, Clarice; Padovan, Júlio C; Greene, Lewis J

    2006-02-01

    Nine chromatographic components containing trypsin inhibitor activity were isolated from Sechium edule seeds by acetone fractionation, gel filtration, affinity chromatography and RP-HPLC in an overall yield of 46% of activity and 0.05% of protein. The components obtained with highest yield of total activity and highest specific activity were sequenced by Edman degradation and their molecular masses determined by mass spectrometry. The inhibitors contained 31, 32 and 27 residues per molecule and their sequences were: SETI-IIa, EDRKCPKILMRCKRDSDCLAKCTCQESGYCG; SETI-IIb, EEDRKCPKILMRCKRDSDCLAKCTCQESGYCG and SETI-V, CPRILMKCKLDTDCFPTCTCRPSGFCG. SETI-IIa and SETI-IIb, which differed by an amino-terminal E in the IIb form, were not separable under the conditions employed. The sequences are consistent with consensus sequences obtained from 37 other inhibitors: CPriI1meCk_DSDCla_C_C_G_CG, where capital letters are invariant amino acid residues and lower case letters are the most preserved in this position. SETI-II and SETI-V form complexes with trypsin with a 1:1 stoichiometry and have dissociation constants of 5.4x10(-11)M and 1.1x10(-9)M, respectively.

  17. Molecular Factors Governing the Liquid and Glassy States Recrystallization of Celecoxib in Binary Mixtures with Excipients of Different Molecular Weights.

    Science.gov (United States)

    Grzybowska, K; Chmiel, K; Knapik-Kowalczuk, J; Grzybowski, A; Jurkiewicz, K; Paluch, M

    2017-04-03

    Transformation of poorly water-soluble crystalline pharmaceuticals to the amorphous form is one of the most promising strategies to improve their oral bioavailability. Unfortunately, the amorphous drugs are usually thermodynamically unstable and may quickly return to their crystalline form. A very promising way to enhance the physical stability of amorphous drugs is to prepare amorphous compositions of APIs with certain excipients which can be characterized by significantly different molecular weights, such as polymers, acetate saccharides, and other APIs. By using different experimental techniques (broadband dielectric spectroscopy, differential scanning calorimetry, X-ray diffraction) we compare the effect of adding the large molecular weight polymer-polyvinylpyrrolidone (PVP K30)-and the small molecular weight excipient-octaacetylmaltose (acMAL)-on molecular dynamics as well as the tendency to recrystallization of the amorphous celecoxib (CEL) in the amorphous solid dispersions: CEL-PVP and CEL-acMAL. The physical stability investigations of the binary systems were performed in both the supercooled liquid and glassy states. We found that acMAL is a better inhibitor of recrystallization of amorphous CEL than PVP K30 deep in the glassy state (T T g ). We discuss molecular factors governing the recrystallization of amorphous CEL in examined solid dispersions.

  18. Evaluation of the degradation effect on the processability of high molecular weight polypropylene

    Energy Technology Data Exchange (ETDEWEB)

    Shinzato, Rodrigo; Otaguro, Harumi; Lima, Luis F.C.P.; Parra, Duclerc F.; Lugao, Ademar B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Quimica e Meio Ambiente], E-mail: rodrigo.shinzato@gmail.com, E-mail: ablugao@ipen.br; Artel, Beatriz W.H. [Empresa Brasileira de Radiacao Ltda. (EMBRARAD), Cotia, SP (Brazil)

    2007-07-01

    One way to improve the processability of high molecular weight and melt strength of Polypropylene (PP) is reducing its molecular weight by chain scission with increase of flow index. Nevertheless, the more significant occurrence of chain scission in its structure, further improved its processability is at expense of physical properties. It is well known that the high energy radiation creates free radicals in the polymer chains that subsequently stabilize forming structures. These structures composed by low molecular weight chains and by grafted, branched and crosslinked chains modify the physical and chemical properties of the polymer, depending of their distribution. The low molecular weight chains become from the degradation process by high energy irradiation, which decreases the melt strength and improves its processability. So, this work has the objective to evaluate the degradation of the high molecular weight PP using different irradiation doses. Two kinds of PP samples were utilized. The first one, without additive, presented a flow index of 1.9 g/10 min, and the second, additivated with 0.2 wt % of antioxidant phenolic, Irganox 1010, with a flow index of 0.9 g/10 min. These samples were irradiated with doses of 12.5 and 20.0 kGy. The results of flow index and melt strength obtained with these two kinds of samples showed the antioxidant and the radiation action. (author)

  19. Low Molecular Weight Chitosan–Insulin Polyelectrolyte Complex: Characterization and Stability Studies

    Directory of Open Access Journals (Sweden)

    Zakieh I. Al-Kurdi

    2015-03-01

    Full Text Available The aim of the work reported herein was to investigate the effect of various low molecular weight chitosans (LMWCs on the stability of insulin using USP HPLC methods. Insulin was found to be stable in a polyelectrolyte complex (PEC consisting of insulin and LMWC in the presence of a Tris-buffer at pH 6.5. In the presence of LMWC, the stability of insulin increased with decreasing molecular weight of LMWC; 13 kDa LMWC was the most efficient molecular weight for enhancing the physical and chemical stability of insulin. Solubilization of insulin-LMWC polyelectrolyte complex (I-LMWC PEC in a reverse micelle (RM system, administered to diabetic rats, results in an oral delivery system for insulin with acceptable bioactivity.

  20. Molecular weight-dependent degradation and drug release of surface-eroding poly(ethylene carbonate)

    DEFF Research Database (Denmark)

    Bohr, Adam; Wang, Yingya; Harmankaya, Necati

    2017-01-01

    Poly(ethylene carbonate) (PEC) is a unique biomaterial showing significant potential for controlled drug delivery applications. The current study investigated the impact of the molecular weight on the biological performance of drug-loaded PEC films. Following the preparation and thorough...... physicochemical characterization of diverse PEC (molecular weights: 85, 110, 133, 174 and 196 kDa), the degradation and drug release behavior of rifampicin- and bovine serum albumin-loaded PEC films was investigated in vitro (in the presence and absence of cholesterol esterase), in cell culture (RAW264.......7 macrophages) and in vivo (subcutaneous implantation in rats). All investigated samples degraded by means of surface erosion (mass loss, but constant molecular weight), which was accompanied by a predictable, erosion-controlled drug release pattern. Accordingly, the obtained in vitro degradation half...

  1. Effect of molecular weight and its distribution on the spinodal for polydisperse polymer solutions

    International Nuclear Information System (INIS)

    Du Xiyan; Sun Zhaoyan; An Lijia

    2005-01-01

    The Flory-Huggins interaction parameter χ(r i ) is considered as dependent on the chain length of a polymer. Therefore, a modified free energy expression of Flory-Huggins theory is obtained for the polydisperse polymer solutions. Based on this modified free energy expression and the thermodynamics of Gibbs, the expression of spinodal for polydisperse polymer solutions is obtained. For a given χ(r i ) according to de Gennes, the spinodals are calculated for polydisperse polymer solutions at different molecular weights and their distributions. It is found that all the interested variables r n , r w , r z and molecular weight distribution have an effect on the spinodal for polydisperse polymer solutions, where the effect of changing r w is much greater than that of changing r n , r z and molecular weight distribution

  2. Acrylate oligomers in ultraviolet cured PSA's glass transition, molecular weight versus peel strength

    International Nuclear Information System (INIS)

    Miller, H.C.

    1999-01-01

    Typically those not skilled in the art relate Glass Transition Temperature to Pressure Sensitive Adhesives. You need a low Tg material to prepare good pressure sensitive adhesives. This report deals with a wide range acrylate terminated oligomers in a standard formulation. Molecular weight, chemical structure variations are examined versus the Glass Transition of the oligomers and final peel strength. Each formulated adhesive will require unique oligomer properties to reach one hundred newtons per 100 millimeters (5.71 pounds per square inch) peel strength. Excellent peel strengths may be obtained with oligomer molecular weight ranging from six thousand to one thousand molecular weight and glass transition temperatures ranging from minus seventy four degrees centigrade up to thirteen degrees centigrade

  3. Thermal characterization of Ag and Ag + N ion implanted ultra-high molecular weight polyethylene (UHMWPE)

    Science.gov (United States)

    Sokullu Urkac, E.; Oztarhan, A.; Tihminlioglu, F.; Kaya, N.; Ila, D.; Muntele, C.; Budak, S.; Oks, E.; Nikolaev, A.; Ezdesir, A.; Tek, Z.

    2007-08-01

    Most of total hip joints are composed of ultra-high molecular weight polyethylene (UHMWPE). However, as ultra-high molecular weight polyethylene is too stable in a body, wear debris may accumulate and cause biological response such as bone absorption and loosening of prosthesis. In this study, ultra-high molecular weight polyethylene samples were Ag and Ag + N hybrid ion implanted by using MEVVA ion implantation technique to improve its surface properties. Samples were implanted with a fluence of 1017 ion/cm2 and extraction voltage of 30 kV. Implanted and unimplanted samples were investigated by thermo-gravimetry analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), optical microscopy (OM) and contact Angle measurement. Thermal characterization results showed that the ion bombardment induced an increase in the % crystallinity, onset and termination degradation temperatures of UHMWPE.

  4. Thermal characterization of Ag and Ag + N ion implanted ultra-high molecular weight polyethylene (UHMWPE)

    Energy Technology Data Exchange (ETDEWEB)

    Sokullu Urkac, E. [Department of Materials Science, Izmir High Technology Institute, Gulbahcekoyu Urla, Izmir (Turkey)]. E-mail: emelsu@gmail.com; Oztarhan, A. [Bioengineering Department, Ege University, Bornova, Izmir 35100 (Turkey); Tihminlioglu, F. [Department of Chemical Engineering, Izmir High Technology Institute, Gulbahcekoyu Urla, Izmir (Turkey); Kaya, N. [Bioengineering Department, Ege University, Bornova, Izmir 35100 (Turkey); Ila, D. [Center for Irradiation of Materials, Alabama A and M University, Normal AL 35762 (United States); Muntele, C. [Center for Irradiation of Materials, Alabama A and M University, Normal AL 35762 (United States); Budak, S. [Center for Irradiation of Materials, Alabama A and M University, Normal AL 35762 (United States); Oks, E. [H C Electronics Institute, Tomsk (Russian Federation); Nikolaev, A. [H C Electronics Institute, Tomsk (Russian Federation); Ezdesir, A. [R and D Department, PETKIM Holding A.S., Aliaga, Izmir 35801 (Turkey); Tek, Z. [Department of Physics, Celal Bayar University, Manisa (Turkey)

    2007-08-15

    Most of total hip joints are composed of ultra-high molecular weight polyethylene (UHMWPE ). However, as ultra-high molecular weight polyethylene is too stable in a body, wear debris may accumulate and cause biological response such as bone absorption and loosening of prosthesis. In this study, ultra-high molecular weight polyethylene samples were Ag and Ag + N hybrid ion implanted by using MEVVA ion implantation technique to improve its surface properties. Samples were implanted with a fluence of 10{sup 17} ion/cm{sup 2} and extraction voltage of 30 kV. Implanted and unimplanted samples were investigated by thermo-gravimetry analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), optical microscopy (OM) and contact Angle measurement. Thermal characterization results showed that the ion bombardment induced an increase in the % crystallinity, onset and termination degradation temperatures of UHMWPE.

  5. Application of protective coatings from ultrahigh-molecular weight polyethylene to butadiene-nitrile rubber

    Science.gov (United States)

    Dyakonov, A. A.; Sokolova, M. D.; Shadrinov, N. V.; Sleptsova, S. A.

    2017-12-01

    The paper presents a method of applying a protective coating from ultrahigh molecular weight polyethylene to rubber products. A distinctive feature of the presented method is the prevulcanization of a rubber compound in order to form it into the desired shape and remove an excess rubber material. The application of an ultrahigh molecular weight polyethylene powder to the prepared surface ensures a uniform coating thickness. To achieve an optimal combination of rubber properties, we study how the scorch time affects its physical and mechanical properties, hardness, corrosion, abrasion and thermal resistance. We find the scorch time range in which a spatial elastomeric network forms that influences the penetration of ultrahigh molecular weight polyethylene into butadiene-nitrile rubber.

  6. Effect of molecular weight on ion diffusion and transference number in poly(ethylene oxide)

    Science.gov (United States)

    Timachova, Ksenia; Balsara, Nitash

    2015-03-01

    Solid polymer electrolytes are of great interest for their potential use in high specific energy, solid-state batteries, however, salt transport properties in polymer electrolytes have not been comprehensively addressed over a wide range of molecular weights. Poly(ethylene oxide) (PEO) has been the most widely studied polymer electrolyte due to its high solvation of lithium salts and low glass transition temperature. This study presents measurements of the transport properties of lithium bis(trifluoromethanesulfone)imide (LiTFSI) in PEO at both the high concentration present in functional electrolytes and in the dilute limit for a large range of PEO molecular weights. Individual diffusion coefficients of the Li + and TFSI- ions were measured using pulsed-field gradient nuclear magnetic resonance and the cation transference number was calculated. The diffusion coefficients, transference number, and conductivity as a function of molecular weight and salt concentration provide a complete set of transport properties for PEO.

  7. Determination of the presence of hyaluronic acid in preparations containing amino acids: the molecular weight characterization.

    Science.gov (United States)

    Bellomaria, A; Nepravishta, R; Mazzanti, U; Marchetti, M; Piccioli, P; Paci, M

    2014-10-15

    Several pharmaceutical preparations contain hyaluronic acid in the presence of a large variety of low molecular weight charged molecules like amino acids. In these mixtures, it is particularly difficult to determine the concentration and the molecular weight of the hyaluronic acid fragments. In fact zwitterionic compounds in high concentration behave by masking the hyaluronic acid due to the electrostatic interactions between amino acids and hyaluronic acid. In such conditions the common colorimetric test of the hyaluronic acid determination appears ineffective and in the (1)H NMR spectra the peaks of the polymer disappear completely. By a simple separation procedure the presence of hyaluronic acid was revealed by the DMAB test and (1)H NMR while its average molecular weight in the final product was determined by DOSY NMR spectroscopy alone. The latter determination is very important due to the healthy effects of some sizes of this polymer's fragments. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Low Molecular Weight Chitosan–Insulin Polyelectrolyte Complex: Characterization and Stability Studies

    Science.gov (United States)

    Al-Kurdi, Zakieh I.; Chowdhry, Babur Z.; Leharne, Stephen A.; Al Omari, Mahmoud M. H.; Badwan, Adnan A.

    2015-01-01

    The aim of the work reported herein was to investigate the effect of various low molecular weight chitosans (LMWCs) on the stability of insulin using USP HPLC methods. Insulin was found to be stable in a polyelectrolyte complex (PEC) consisting of insulin and LMWC in the presence of a Tris-buffer at pH 6.5. In the presence of LMWC, the stability of insulin increased with decreasing molecular weight of LMWC; 13 kDa LMWC was the most efficient molecular weight for enhancing the physical and chemical stability of insulin. Solubilization of insulin-LMWC polyelectrolyte complex (I-LMWC PEC) in a reverse micelle (RM) system, administered to diabetic rats, results in an oral delivery system for insulin with acceptable bioactivity. PMID:25830681

  9. Rheological properties of poly (vinylpiyrrolidone) as a function of average molecular weight and its applications

    DEFF Research Database (Denmark)

    Marani, Debora; Sudireddy, Bhaskar Reddy; Kiebach, Ragnar

    of formulations for pharmaceutics, food, personal care, or coatings, paintings, and printing applications. It is also widely used as organic additive, i.e. dispersant for ceramics. Regardless of the application, the control over the polymer behavior in solution is required for an efficient optimization...... of the formulation. Specifically, understanding the rheological properties is of paramount interest. Among the different factors that influence the rheological behavior, viscosity average molecular weight of the polymer is the most relevant. In this work, PVP polymers with various molecular weights have been....... The MHS equation relates the intrinsic viscosity [η] of a polymer in a given solvent at fixed temperature to the molecular weight. The adopted method also enables for the evaluation of the two MHS equation parameters (a and K), and of the polydispersity correction factor (qMHS). The intrinsic viscosity...

  10. Synthetic polycations with controlled charge density and molecular weight as building blocks for biomaterials.

    Science.gov (United States)

    Kleinberger, Rachelle M; Burke, Nicholas A D; Zhou, Christal; Stöver, Harald D H

    2016-01-01

    A series of polycations prepared by RAFT copolymerization of N-(3-aminopropyl)methacrylamide hydrochloride (APM) and N-(2-hydroxypropyl)methacrylamide, with molecular weights of 15 and 40 kDa, and APM content of 10-75 mol%, were tested as building blocks for electrostatically assembled hydrogels such as those used for cell encapsulation. Complexation and distribution of these copolymers within anionic calcium alginate gels, as well as cytotoxicity, cell attachment, and cell proliferation on surfaces grafted with the copolymers were found to depend on composition and molecular weight. Copolymers with lower cationic charge density and lower molecular weight showed less cytotoxicity and cell adhesion, and were more mobile within alginate gels. These findings aid in designing improved polyelectrolyte complexes for use as biomaterials.

  11. Calibration of low molecular weight polypeptides by sodium dodecylsulphate polyacrylamide gel electrophoresis

    International Nuclear Information System (INIS)

    Glyn, M.C.P.; Bull, J.; Wright, R.

    1982-01-01

    Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) is a technique commonly used in determining molecular weights of large proteins and peptides. This technique is used to analyse viral peptides, available in amounts too small to be monitored by an ultraviolet spectrophotometer. An experiment is described (with the limiting factor to use the SDS-PAGE technique), to determine the molecular weight peptides and the results are given to fit the linear relationship log M=4.286 - 0.42 V(e)/V(o). The results given by the SDS-PAGE system, described in the article, show that the experimental values describe a linear relationship with good resolution of low molecular weight peptides in the range 3 000 to 14 000 and that a partial cyanogen bromide digest of cytochrome c is suitable for calibration standards

  12. Molecular weight-dependent degradation and drug release of surface-eroding poly(ethylene carbonate).

    Science.gov (United States)

    Bohr, Adam; Wang, Yingya; Harmankaya, Necati; Water, Jorrit J; Baldursdottír, Stefania; Almdal, Kristoffer; Beck-Broichsitter, Moritz

    2017-06-01

    Poly(ethylene carbonate) (PEC) is a unique biomaterial showing significant potential for controlled drug delivery applications. The current study investigated the impact of the molecular weight on the biological performance of drug-loaded PEC films. Following the preparation and thorough physicochemical characterization of diverse PEC (molecular weights: 85, 110, 133, 174 and 196kDa), the degradation and drug release behavior of rifampicin- and bovine serum albumin-loaded PEC films was investigated in vitro (in the presence and absence of cholesterol esterase), in cell culture (RAW264.7 macrophages) and in vivo (subcutaneous implantation in rats). All investigated samples degraded by means of surface erosion (mass loss, but constant molecular weight), which was accompanied by a predictable, erosion-controlled drug release pattern. Accordingly, the obtained in vitro degradation half-lives correlated well with the observed in vitro half-times of drug delivery (R 2 =0.96). Here, the PEC of the highest molecular weight resulted in the fastest degradation/drug release. When incubated with macrophages or implanted in animals, the degradation rate of PEC films superimposed the results of in vitro incubations with cholesterol esterase. Interestingly, SEM analysis indicated a distinct surface erosion process for enzyme-, macrophage- and in vivo-treated polymer films in a molecular weight-dependent manner. Overall, the molecular weight of surface-eroding PEC was identified as an essential parameter to control the spatial and temporal on-demand degradation and drug release from the employed delivery system. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Biocompatibility of low molecular weight polymers for two-phase partitioning bioreactors.

    Science.gov (United States)

    Harris, Jesse; Daugulis, Andrew J

    2015-12-01

    Two phase partitioning bioreactors (TPPBs) improve the efficiency of fermentative processes by limiting the exposure of microorganisms to toxic solutes by sequestering them into a non-aqueous phase (NAP). A potential limitation of this technology, when using immiscible organic solvents as the NAP, is the cytoxicity that these materials may exert on the microbes. An improved TPPB configuration is one in which polymeric NAPs are used to replace organic solvents in order to take advantage of their low cost, improved handling qualities, and biocompatibility. A recent study has shown that low molecular weight polymers may confer improved solute uptake relative to high molecular weight polymers (i.e., have higher partition coefficients), but it is unknown whether sufficiently low molecular weight polymers may inhibit cell growth. This study has investigated the biocompatibility of a range of low molecular weight polymers, and compared trends in biocompatibility to the well-established "critical log P" concept. This was achieved by determining the biocompatibility of polypropylene glycol polymers over a molecular weight (MW) range of 425-4,000 to Saccharomyces cerevisiae and Pseudomonas putida, two organisms which have been previously used in TPPB systems. The lower MW polymers were shown to have lower average log P values, and showed more cytotoxicity than polymers of the same structure but with higher molecular weight. Since polymers are generally polydisperse (i.e., polymer samples contain a distribution of MWs), removal of the lower MW fractions via water washing was found to result in improved polymer biocompatibility. These results suggest that the critical log P concept remains useful for describing the toxicity of polymeric substances of different MWs, although it is complicated by the presence of the low MW fractions in the polymers arising from polydispersity. © 2015 Wiley Periodicals, Inc.

  14. Effect of molecular weight on the vibronic structure of a diketopyrrolopyrrole polymer

    KAUST Repository

    Hayes, Sophia C.

    2016-09-27

    Resonance Raman Spectroscopy (RRS) is employed in this study to examine the influence of molecular weight on the optical response of a diketopyrrolopyrrole polymer (DPP-TT-T) in solution. The vibronic structure observed for the ground state absorption of this polymer is found to vary with molecular weight and solvent. Resonance Raman Intensity Analysis (RRIA) revealed that the absorption spectra can be described by at least two dipole-allowed transitions and the vibronic structure variation is due to differing contributions from linear and curved segments of the polymer.

  15. Correlation between the estimated molecular weight and the immunological properties of 125I-TSH

    International Nuclear Information System (INIS)

    Quiroga, S.E.; Ciscato, V.A.; Barmasch, M.; Kurcbart, H.; Veira de Giacomini, S.; Altschuler, N.; Caro, R.A.

    1976-09-01

    Thyrotropic Stimulating Hormone (TSH) was radioiodinated by the Chloramine T method in order to be used in radioimmu-noassay procedures. It was purified by gel filtration and each fraction of the eluate was analyzed in order to determine which one had the most suitable behaviour for that use. The molecular weight of each fraction was estimated, as well as its immunological reactivity and its non-specific binding. The 125 I-TSH fraction with better properties was the closest to the molecular weight of the native hormone, which is found at the posterior shoulder of the main proteic peak of the elution pattern. (author) [es

  16. Low Molecular Weight Z-Tetraol Boundary Lubricant Films in Hard Disk Drives

    Directory of Open Access Journals (Sweden)

    R. J. Waltman

    2012-01-01

    Full Text Available Lower molecular weight Z-Tetraol films exhibit increased mechanical spacing in the slider-disk interface due to a lower z-profile. An increased resistance to lubricant disturbance on the disk surface (e.g., lube moguls with decreasing film thickness is attributed to an increasing contribution from the polar component of the disjoining pressure. Evaporative loss at temperatures typically encountered in a hard-disk drive also increases with decreasing molecular weight but is strongly dependent on the initial bonded fraction.

  17. Molecular weight dependence of carrier mobility and recombination rate in neat P3HT films

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, Alex G. [Department of Physics, University of Denver, Colorado 80208; Visvanathan, Rayshan [Department of Physics, University of Colorado, Boulder Colorado 80309; Clark, Noel A. [Department of Physics, University of Colorado, Boulder Colorado 80309; Stingelin, Natalie [Department of Materials and Centre for Plastic Electronics, Imperial College London, South Kensington Campus, London SW7 2AZ United Kingdom; Kopidakis, Nikos [National Renewable Energy Laboratory, 1617 Cole Blvd, Golden Colorado 80401; Shaheen, Sean E. [Department of Physics, University of Colorado, Boulder Colorado 80309; Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder Colorado 80309; Renewable and Sustainable Energy Institute, University of Colorado, Boulder Colorado 80309

    2017-11-02

    The microstructure dependence of carrier mobility and recombination rates of neat films of poly 3-hexylthyophene (P3HT) were determined for a range of materials of weight-average molecular weights, Mw, ranging from 14 to 331 kDa. This variation has previously been shown to modify the polymer microstructure, with low molecular weights forming a one-phase, paraffinic-like structure comprised of chain-extended crystallites, and higher molecular weights forming a semicrystalline structure with crystalline domains being embedded in an amorphous matrix. Using Charge Extraction by Linearly Increasing Voltage (CELIV), we show here that the carrier mobility in P3HT devices peaks for materials of Mw = 48 kDa, and that the recombination rate decreases monotonically with increasing molecular weight. This trend is likely due to the development of a semicrystalline, two-phase structure with increasing Mw, which allows for the spatial separation of holes and electrons into the amorphous and crystalline regions, respectively. This separation leads to decreased recombination.

  18. Synthesis and properties of aqueous polyurethane dispersions: Influence of molecular weight of polyethylene glycol

    Energy Technology Data Exchange (ETDEWEB)

    Mumtaz, Fatima; Zuber, Mohammad; Zia, Khalid Mahmood [Government College University, Faisalabad (Pakistan); Jamil, Tahir [University of the Punjab, Lahore (Pakistan); Hussain, Rizwan [National Engineering and Scientific Commission (NESCOM), Islamabad (Pakistan)

    2013-12-15

    Aqueous polyurethane dispersions (PUDs) have recently emerged as important alternatives to their solvent-based counterparts for various applications due to increasing health and environmental awareness. A series of aqueous polyurethane dispersions containing carboxylate anion as hydrophilic pendant groups were synthesized through step growth polymerization reaction using hexamethylene diisocyanate (HDI), 1,4-butanediol (1,4-BDO), dimethylol propionic acid (DMPA) and polyethylene glycol (PEG) of different molecular weight. Effect of PEG molecular weight was investigated on molecular structure, contact angle measurement, and physical and adhesive properties of PU emulsions. Fourier transform infrared spectroscopy (FT-IR) was used to check the completion of polymerization reaction. Contact angle measurement indicated that the hydrophilicity of polymer increases by increasing molecular weight of PEG with a corresponding decrease in contact angle. Results of T-peel test showed a decrease in peel strength by increasing molecular weight of PEG. Moreover, solid contents%, drying time and storage stability suggested fast drying properties and greater stability of aqueous PU dispersions.

  19. Prediction models for drug-induced hepatotoxicity by using weighted molecular fingerprints

    OpenAIRE

    Kim, Eunyoung; Nam, Hojung

    2017-01-01

    Background Drug-induced liver injury (DILI) is a critical issue in drug development because DILI causes failures in clinical trials and the withdrawal of approved drugs from the market. There have been many attempts to predict the risk of DILI based on in vivo and in silico identification of hepatotoxic compounds. In the current study, we propose the in silico prediction model predicting DILI using weighted molecular fingerprints. Results In this study, we used 881 bits of molecular fingerpri...

  20. Pulsed NMR studies of crosslinking and entanglements in high molecular weight linear polydimethylsiloxanes

    International Nuclear Information System (INIS)

    Folland, R.; Charlesby, A.

    1977-01-01

    Pulsed NMR studies of proton spin relaxation are used to investigate both radiation-induced cross linking and entanglements in three high molecular weight linear polydimethylsiloxanes (Msub(w) = 26,000, 63,000 and 110,000). Particular emphasis is placed on the spin-spin relaxation since this is determined by the slower relative translational motions of the polymer chains and hence profoundly affected by the presence of intermolecular couplings such as crosslinks or entanglements. The spin-lattice relaxation times, T 1 , are determined by the fast anisotropic chain rotations and are rather insensitive to such intermolecular couplings. The spin-spin relaxation in these materials is represented by a double exponential decay involving two time constants, Tsub(2S) and Tsub(2L). The shorter component, Tsub(2S), is attributed to network material, which may be either of a dynamic form arising from temporary entanglements or of a permanent nature due to crosslinks. The concentration of entanglements depends on the initial molecular weight of the sample whereas the concentration of crosslinks is a function of the radiation dose. The longer component, Tsub(2L), is attributed to the non-network molecules. On the time scale of the NMR measurements the entanglements are shown to act in the same way as crosslinks. The variation of the relative proportions of network and non-network material with dose is shown to be accounted for by using standard gelation theory when allowance is made for the initial effective crosslink density due to entanglements. The analysis provides a value for the average molecular weight per entanglement point of 27,000 +- 1000 which is consistent with the critical molecular weight for entanglements of 29,000. The dependences of Tsub(2S) and Tsub(2L) on dose and molecular weight are also discussed in terms of the molecular motion. (author)

  1. Microstructural Investigation and MolecularWeight Determination of 1, 2-Polybutadiene by Nuclear Magnetic Resonance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Farshid Ziaee

    2013-01-01

    Full Text Available In this research, the microstructural of low molecular weight 1,2-polybutadiene (1,2-PBD was conducted by 1H and 13C nuclear magnetic resonance spectroscopy (NMR to determine the isomeric contents of 1,4-cis, 1,4-trans and 1,2-vinyl in 1,2-PBD polymer structures. Number average molecular weight for low molecular weight 1,2-PBD was measured by NMR techniques and the results were compared with gel permeation chromatography. Due to the presence of methyl end group and its comparison with repeating units in 1,2-PBD microstructure, the number average molecular weight was calculated by NMR techniques. For calculation of surface areas, carbon and protons of methyl groups were characterized using distortion enhancement by polarization transfer (DEPT methods. For proton assignment of methyl end groups in 1H NMR spectral analysis the heteronuclear multiple quantum coherence (HMQC method was employed. Finally, stereoregularity and tacticity of 1,2-PBD were investigated through pentad and heptad sequences splitting of olefinic methylene and methine carbons pendant groups with various NMR acquisition temperatures from 20 to 50oC. 13C NMR spectra showed that with increasing of NMR acquisition temperature, the number of split peaks of two olefinic carbons increased.

  2. Intercalation Study of Low-Molecular-Weight Hyperbranched Polyethyleneimine into Graphite Oxide

    NARCIS (Netherlands)

    Tsoufis, Theodoros; Katsaros, Fotios; Sideratou, Zili; Kooi, Bart J.; Karakassides, Michael. A.; Siozios, Anastasios

    2014-01-01

    We report for the first time the intercalation of low-molecular-weight hyperbranched polyethyleneimine (PEI) into graphite oxide (GO) for the facile, bulk synthesis of novel graphene-based hybrid (GO-PEI) materials exhibiting tailored interlayer galleries. The size of the intercalant as well as the

  3. Exploratory data analysis of the dependencies between skin permeability, molecular weight and log P.

    Science.gov (United States)

    Kilian, D; Lemmer, H J R; Gerber, M; du Preez, J L; du Plessis, J

    2016-06-01

    Molecular weight and log P remain the most frequently used physicochemical properties in models that predict skin permeability. However, several reports over the past two decades have suggested that predictions made by these models may not be sufficiently accurate. In this study, exploratory data analysis of the probabilistic dependencies between molecular weight, log P and log Kp was performed on a dataset constructed from the combination of several popular datasets. The results suggest that, in general, molecular weight and log P are poorly correlated to log Kp. However, after employing several exploratory data analysis techniques, regions within the dataset of statistically significant dependence were identified. As an example of the applicability of the information extracted from the exploratory data analyses, a multiple linear regression model was constructed, bounded by the ranges of dependence. This model gave reasonable approximations to log Kp values obtained from skin permeability studies of selected non-steroidal ant-inflammatory drugs (NSAIDs) administered from a buffer solution and a lipid-based drug delivery system. A method of testing whether a given drug falls within the regions of statistical dependence was also presented. Knowing the ranges within which molecular weight and log P are statistically related to log Kp can supplement existing methods of screening, risk analysis or early drug development decision making to add confidence to predictions made regarding skin permeability.

  4. Synthesis and Direct Imaging of Ultrahigh Molecular Weight Cyclic Brush Polymers

    OpenAIRE

    Xia, Yang; Boydston, Andrew J.; Grubbs, Robert H.

    2011-01-01

    Convenient route to cyclic polymers: Ultrahigh molecular weight cyclic brush polymers were synthesized through ring-expansion metathesis polymerization of various macromonomers. Atomic force microscopy was used to visualize toroidal shapes and large opening pores, along with linear chains, which may result from high sensitivity of brush polymers to mechanical degradation.

  5. A 7-d exercise program increases high-molecular weight adiponectin in obese adults

    DEFF Research Database (Denmark)

    Kelly, Karen R; Blaszczak, Alecia; Haus, Jacob M

    2012-01-01

    High-molecular weight (HMW) adiponectin is the biologically active form of adiponectin and is related to enhanced insulin sensitivity and metabolic function. Previously, we found that 7 d of exercise improves insulin sensitivity in obese subjects; however, whether short-term exercise training...

  6. Rheological properties of poly(vinylpiyrrolidone) as a function of molecular weight

    DEFF Research Database (Denmark)

    Marani, Debora; Sudireddy, Bhaskar Reddy; Kiebach, Wolff-Ragnar

    2014-01-01

    Different grades of poly (vinylpyrrolidone) (PVP) were studied as dispersant for gadolinium doped cerium oxide (CGO) in ethanol-based colloidal dispersions. The average molecular weights Mw, Mn, and Mz were determined by gel permeation chromatography (GPC), and then used in a numerical method...

  7. Autoadhesion of high-molecular-weight polystyrene and poly(methyl methacrylate) at room temperature

    DEFF Research Database (Denmark)

    Boiko, Y.M.; Lyngaae-Jørgensen, Jørgen

    2005-01-01

    Measurements of the shear strength of adhesion joints revealed the autoadhesion of high-molecular-weight PS (polydisperse and monodisperse polymers) and PMMA at 24 degrees C, that is 75-85 degrees C below the calorimetric glass transition temperature of the polymer bulk, provided that the time of...

  8. Entrapment and release of quinoline derivatives using a hydrogel of a low molecular weight gelator

    NARCIS (Netherlands)

    Friggeri, A; Feringa, BL; van Esch, J; Feringa, Bernard

    2004-01-01

    Gels of low molecular weight gelators (LMWGs) are self-assembled, thermoreversible, viscoelastic materials which can also be rendered sensitive to light, pH or chemical substances by simple chemical modifications. In addition, the ability of some of these LMWGs to gelate water (hydrogelators) makes

  9. Modulation of Src Activity by Low Molecular Weight Protein Tyrosine Phosphatase During Osteoblast Differentiation

    NARCIS (Netherlands)

    Zambuzzi, Willian F.; Granjeiro, Jose M.; Parikh, Kaushal; Yuvaraj, Saravanan; Peppelenbosch, Maikel P.; Ferreira, Carmen V.

    2008-01-01

    Background: Src kinase plays a critical role in bone metabolism, particularly in osteoclasts. However, the ability of Src kinase to modulate the activity of other bone cells is less well understood. In this work, we examined the expression and activity of Src and low molecular weight protein

  10. Growth of thin films of low molecular weight proteins by matrix assisted pulsed laser evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Matei, Andreea; Schou, Jørgen; Constantinescu, C.

    2011-01-01

    Thin films of lysozyme and myoglobin grown by matrix assisted pulsed laser evaporation (MAPLE) from a water ice matrix have been investigated. The deposition rate of these two low molecular weight proteins (lysozyme: 14307 amu and myoglobin: 17083 amu) exhibits a maximum of about 1–2 ng/cm2 per...

  11. Extension induced phase separation and crystallization in semidilute solutions of ultra high molecular weight polyethylene

    DEFF Research Database (Denmark)

    Wingstrand, Sara Lindeblad; Imperiali, Luna; Stepanyan, Roman

    2018-01-01

    Abstract We investigate the influence of controlled uniaxial extension on various flow induced phenomena in semidilute solutions of ultra high molecular weight polyethylene (UHMwPE). Concentrations range from 9 w% to 29 w% and the choice of solvent is paraffin oil (PO). The start-up extensional b...

  12. In vitro studies of PEG thin films with different molecular weights deposited by MAPLE

    DEFF Research Database (Denmark)

    Paun, Irina Alexandra; Ion, Valentin; Luculescu, Catalin-Romeo

    2012-01-01

    In this work, polyethylene glycol (PEG) films were produced by Matrix Assisted Pulsed Laser Evaporation (MAPLE). The possibility to tailor the properties of the films by means of polymer molecular weight was explored. The films of PEG of average molecular weights 400 Da, 1450 Da, and 10000 Da (PEG...... and their behavior in vitro. Thus, immersion in PBS induced swelling of the PEG films, which was more pronounced for PEG polymers of higher molecular weight. Prior to immersion in PBS, the PEG films of higher molecular weight were more hydrophilic, the water contact angles decreasing from ∼66 grd for PEG400 to ∼41...... grd for PEG 1450 and to ∼15 grd for PEG10000. The same trend was observed during immersion of the PEG films in PBS. Before immersion in PBS, the refractive index of the films increased from ∼1.43 for PEG400 to ∼1.48 for PEG1450 and to ∼1.68 for PEG10000. During immersion in PBS the refractive index...

  13. High molecular weight FGF2: the biology of a nuclear growth factor

    Czech Academy of Sciences Publication Activity Database

    Chlebová, K.; Bryja, Vítězslav; Dvořák, Petr; Kozubík, Alois; Wilcox, W.R.; Krejčí, Pavel

    2009-01-01

    Roč. 66, č. 2 (2009), s. 225-235 ISSN 1420-682X Grant - others:GA MŠk(CZ) LC06077 Program:LC Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : high molecular weight * FGF2 * nuclear Subject RIV: BO - Biophysics Impact factor: 6.090, year: 2009

  14. Tumor microvascular changes in antiangiogenic treatment : Assessment by magnetic resonance contrast media of different molecular weights

    NARCIS (Netherlands)

    Turetschek, K; Preda, A; Novikov, [No Value; Brasch, RC; Weinmann, HJ; Wunderbaldinger, P; Roberts, TPL

    Purpose: To test magnetic resonance (MR) contrast media of different molecular weights (MWs) for their potential to characterize noninvasively microvascular changes in an experimental tumor treatment model. Materials and Methods: MD-MBA-435, a poorly differentiated human breast cancer cell line, was

  15. Pilot-scale recovery of low molecular weight organic acids from ...

    African Journals Online (AJOL)

    Pilot-scale recovery of low molecular weight organic acids from anaerobically treated palm oil mill effluent (POME) with energy integrated system. ... The recovery of organic acids has a significant and economical impact, since around 50% cost of PHA production is believed to be associated with the substrate itself.

  16. Nanometer size wear debris generated from ultra high molecular weight polyethylene in vivo

    Czech Academy of Sciences Publication Activity Database

    Lapčíková, Monika; Šlouf, Miroslav; Dybal, Jiří; Zolotarevova, E.; Entlicher, G.; Pokorný, D.; Gallo, J.; Sosna, A.

    2009-01-01

    Roč. 266, 1-2 (2009), s. 349-355 ISSN 0043-1648 R&D Projects: GA MŠk 2B06096 Institutional research plan: CEZ:AV0Z40500505 Keywords : ultra high molecular weight polyethylene * nanometer size wear debris * morphology of wear particles Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.771, year: 2009

  17. Effect of mahlep on molecular weight distribution of cookie flour gluten proteins

    Science.gov (United States)

    Size Exclusion-High performance Chromatography (SE-HPLC) has been extensively used in molecular weight distribution analysis of wheat proteins. In this study the protein analysis was conducted on different cookie dough blends with different percentages of some ingredients. The mean chromatography ...

  18. Loss of high-molecular-weight cytokeratin antigenicity in prostate tissue obtained by transurethral resections.

    Science.gov (United States)

    Multhaupt, H A; Fessler, J N; Warhol, M J

    2000-12-01

    Staining of prostatic basal cells for the expression of high-molecular-weight cytokeratin has been suggested as a way of distinguishing benign from malignant prostate glands. We evaluated the utility of high-molecular-weight cytokeratin in the diagnosis of malignancy in prostate specimens obtained in various ways. Prostate tissues obtained from needle biopsies, transurethral resections, and total prostatectomies were immunostained with monoclonal antibody 34betaE12, an antibody directed against high-molecular-weight cytokeratins. Antiserum to high-molecular-weight cytokeratin only stained the basal cells in normal glands in 3 (12%) of 25 specimens obtained by transurethral resection. Other antigens, such as the alternate 10-nm filament protein vimentin, were unaffected and were detected in 100% of these specimens. However, keratin antigenicity in transurethral biopsies could be restored in these specimens by antigen retrieval in a low pH citrate buffer using a microwave heat technique. Keratin staining in needle biopsies and total prostatectomies was unaffected. In summary, our results indicate the technique of transurethral resection results in a specific loss of keratin antigenicity. This limits the utility of anticytokeratin 34betaE12 in interpreting transurethral resections without the application of antigen retrieval.

  19. Methanol-induced chain termination in poly(3-hydroxybutyrate) biopolymers: molecular weight control

    Science.gov (United States)

    A systematic study was performed to demonstrate the impact of methanol (MeOH) on poly(3-hydroxybutyrate) (PHB) synthesis and molecular weight (MW) control. Glycerine (init. conc. = 1.0%; w/v), was used as the primary carbon source in batch-culture fermentations with varying concentrations (0 to 0.85...

  20. A global survey of low-molecular weight carbohydrates in lentils

    Science.gov (United States)

    Lentils contain a range of low-molecular weight carbohydrates (LMWC); however, those have not been well characterized. The objectives of this study were to (1) determine the concentrations of LMWC in lentils grown in six locations, and (2) identify any genetic and environmental effects on those LMWC...

  1. The effect of chitosan molecular weight on the properties of alginate ...

    African Journals Online (AJOL)

    Purpose: The aim of the present study was to investigate the effect of chitosan molecular weight on size, size distribution, release rate, mucoadhesive properties and electrostatic bonding of alginate/chitosan microparticles containing prednisolone. Methods: Three mucoadhesive alginate/chitosan microparticle formulations, ...

  2. Infiltration and Erosion in Soils Treated with Dry PAM of Two Molecular Weights and Phosphogypsum

    Science.gov (United States)

    Soil surface application of dissolved linear polyacrylamide (PAM) of high molecular weight (MW) can mitigate seal formation, runoff and erosion, especially when added with a source of electrolytes (e.g., gypsum). Practical difficulties associated with PAM solution application prohibited commercial u...

  3. Polyacrylamide molecular weight and phosphogypsum effects on infiltration and erosion in semi-arid soils

    Science.gov (United States)

    Seal formation at the surface of semi-arid soils during rainstorms reduces soil infiltration rate (IR) and causes runoff and erosion. Surface application of dry anionic polyacrylamide (PAM) with high molecular weight (MW) has been found to be effective in stabilizing soil aggregates, and decreasing ...

  4. Dietary factors associated with plasma high molecular weight and total adiponectin levels in apparently healthy women

    NARCIS (Netherlands)

    Yannakoulia, Mary; Yiannakouris, Nikos; Melistas, Labros; Fappa, Evaggelia; Vidra, Nikoletta; Kontogianni, Meropi D; Mantzoros, Christos S

    2008-01-01

    OBJECTIVE: Our aim was to investigate associations between dietary factors and high molecular weight (HMW) as well as total adiponectin in a sample of apparently healthy adult Mediterranean women. DESIGN AND METHODS: Two hundred and twenty women were enrolled in this study. Anthropometric and body

  5. Reversible, High Molecular Weight Palladium and Platinum Coordination Polymers Based on Phosphorus Ligands

    NARCIS (Netherlands)

    Paulusse, Jos Marie Johannes; Huijbers, Jeroen P.J.; Sijbesma, Rint P.

    2005-01-01

    A general strategy for the preparation and characterization of high molecular weight coordination polymers based on bifunctional phosphorus ligands and palladium or platinum dichloride is described. Metal-to-ligand stoichiometry is of key importance for the formation of linear coordination polymers

  6. Effects of pH of medium and molecular weight on polyelectrolyte ...

    African Journals Online (AJOL)

    The effects of pH of medium and molecular weight of chitosan on polyelectrolyte complex (PEC) formation between pectin and chitosan was investigated using capillary viscometry. The intrinsic viscosity of the polymers was determined using Huggin's plot. PECs were formed between pectin and chitosan in the pH range ...

  7. Does low-molecular-weight heparin influence the antimyeloma effects of thalidomide?

    DEFF Research Database (Denmark)

    Beksac, Meral; Waage, Anders; Bringhen, Sara

    2015-01-01

    BACKGROUND/AIM: Low-molecular-weight heparin (LMWH) has been shown to prolong survival among patients with solid tumors, but its role among myeloma patients is unknown. PATIENTS: Data from the GIMEMA (Gruppo Italiano Malattie Ematologiche dell'Adulto), Nordic and Turkish myeloma study groups...

  8. Unfractionated or Low-Molecular Weight Heparin for the Treatment of Cerebral Venous Thrombosis

    NARCIS (Netherlands)

    Coutinho, Jonathan M.; Ferro, José M.; Canhão, Patrícia; Barinagarrementeria, Fernando; Bousser, Marie-Germaine; Stam, Jan

    2010-01-01

    Background and Purpose-There is no consensus whether to use unfractionated heparin or low-molecular weight heparin for the treatment of cerebral venous thrombosis. We examined the effect on clinical outcome of each type of heparin. Methods-A nonrandomized comparison of a prospective cohort study

  9. Prolonged thromboprophylaxis with low molecular weight heparin for abdominal or pelvic surgery

    DEFF Research Database (Denmark)

    Rasmussen, Morten Schnack; Jørgensen, Lars Nannestad; Wille-Jørgensen, Peer

    2009-01-01

    BACKGROUND: Major abdominal and pelvic surgery carries a high risk of venous thromboembolism (VTE). The efficacy of thromboprophylaxis with low-molecular weight heparin (LMWH) administered during the in-hospital period is well documented, but the optimal duration of thromboprophylaxis after surgery...

  10. Pilot-scale recovery of low molecular weight organic acids from ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-11-05

    Nov 5, 2008 ... Low molecular weight organic acids such as acetic acid, propionic acid and butyric acids generated from partial anaerobic ... nogenic phases would enhance the overall rate of waste stabilization if maintained in ..... from anaerobically treated palm oil mill effluent by ion exchange resins for the production of ...

  11. Adhesives, fillers & potting compounds: Special report molecular weight determinations of dimethypolysiloxane polymers

    Energy Technology Data Exchange (ETDEWEB)

    Luthey, Z.A.

    1968-09-03

    Using a Mechrolab Vapor Phase Osmometer and a Hallikainen Automatic Membrane Osmometer the number-average molecular weight of two samples of dimethylpolysiloxane - 2300 and 8000 cstk - as well as samples made by mixing the two previously mentioned materials were determined.

  12. Drug delivery to the kidneys and the bladder with the low molecular weight protein lysozyme

    NARCIS (Netherlands)

    Kok, Robbert J.; Haas, Marijke; Moolenaar, Frits; de Zeeuw, Dick; Meijer, Dirk K.F.

    1998-01-01

    The low molecular weight protein (LMWP) lysozyme is a suitable drug carrier for renal drug targeting. When the tubular reabsorption of a can be prevented, the protein will be excreted in the urine. In this way, lysozyme (LZM) conjugates might also be used as carriers for targeting to the urinary

  13. Drug delivery to the kidneys and the bladder with the low molecular weight protein lysozyme

    NARCIS (Netherlands)

    Kok, RJ; Haas, M; Moolenaar, F; de Zeeuw, D; Meijer, DKF

    1998-01-01

    The low molecular weight protein (LMWP) lysozyme is a suitable drug carrier for renal drug targeting. When the tubular reabsorption of a LMWP can be prevented, the protein will be excreted in the urine. In this way lysozyme (LZM) conjugates might also be used as carriers for targeting to the urinary

  14. Differential Modulation of Cellular Bioenergetics by Poly(L-lysine)s of Different Molecular Weights

    DEFF Research Database (Denmark)

    Hall, Arnaldur; Wu, Lin-Ping; Parhamifar, Ladan

    2015-01-01

    Poly(L-lysine)s (PLLs), and related derivatives, have received considerable attention as nonviral vectors. High molecular weight PLLs (H-PLLs) are superior transfectants compared with low Mw PLLs (L-PLLs), but suggested to be more cytotoxic. Through a pan-integrated metabolomic approach using Sea...

  15. Fighting high molecular weight in bioactive molecules with sub-pharmacophore-based virtual screening.

    Science.gov (United States)

    von Korff, Modest; Freyss, Joel; Sander, Thomas; Boss, Christoph; Ciana, Claire-Lise

    2012-02-27

    A new subpharmacophore-based virtual screening method is introduced. Subpharmacophores are derived from large active molecules to detect small bioactive molecules as seeds for starting points in medicinal chemistry programs. A large data set was assembled from the ChEMBL database to check the validity of this approach. Molecules for 133 targets with molecular weights between 450 and 850 were selected as queries. For the query molecules, the pharmacophore descriptors were calculated. Up to 56 000 subpharmacophore descriptors with five to seven pharmacophore points were derived from the query pharmacophores. The subpharmacophore descriptors were used as queries to screen 1079 test data sets, containing decoys and spike molecules. A maximum upper molecular weight limit of 400 Da was set for the test molecules. Three different chemical fingerprint descriptors were used for comparison purposes. The subpharmacophore approach detected active molecules for 85 out of 133 targets and outperformed the chemical fingerprints. This ligand-based virtual screening experiment was triggered by the needs of medicinal chemistry. Applying the subpharmacophore method in a medicinal chemistry program, where a lead molecule with a molecular weight of 800 Da was available, resulted in a new series of molecules with molecular weights below 400.

  16. Control of radio degradation of natural polymers by measurement of viscosity and molecular weight determination

    International Nuclear Information System (INIS)

    Nabinger Machado, Patricia; Cerchietti, Maria Luciana; Mondino, Angel V.; Smolko, Eduardo E.

    2009-01-01

    Applications are now being made in various fields of oligosaccharides obtained by the depolymerization of large molecules such as natural alginates, carrageenan, pectin and chitosan. Find use in various disciplines such as crop production, sanitation, pharmacy, cosmetics, etc. Given the diversity of origins of these materials, almost all of marine origin, was the need for universal methods for recognition and composition, then the possible ways to get processed. A centralized program by the IAEA is promoting the use of ionizing radiation for these changes. This paper resents the calculations used to obtain the molecular weight of polysaccharides from determinations of viscosity. It has been found the molecular weight of sodium alginate and kappa-carrageenan irradiated with cobalt-60 gamma rays at doses between 2 and 35 kGy in solid state. We used a capillary Cannon Viscometer Ubbelohde-type and a protocol for standardized calculation procedure for this purpose. Were obtained reading times for passage through the capillary Viscometer, with various concentrations of polymer solutions of virgin material and the irradiated and from there calculated the relative viscosities, specific, inherent, reduced and intrinsic and then using the ratio of Mark-Houwink-SAKURADA calculate the viscosity average molecular weight of the different polymers. The changes found in the molecular weights by radio-depolymerization reach two orders of magnitude in some cases giving oligosaccharides of 8-12 monomer units. It is considered that this depolymerization method is effective and inexpensive compared to enzymatic or chemical methods. (author)

  17. The impact of treatment density and molecular weight for fractional laser-assisted drug delivery

    DEFF Research Database (Denmark)

    Haak, Christina S; Bhayana, Brijesh; Farinelli, William A

    2012-01-01

    treatment density (% of skin occupied by channels) and molecular weight (MW) for fractional CO(2) laser-assisted drug delivery. AFXL substantially increased intra- and transcutaneous delivery of polyethylene glycols (PEGs) in a MW range from 240 to 4300 Da (Nuclear Magnetic Resonance, p...

  18. High molecular weight kininogen binds to laminin--characterization and kinetic analysis

    DEFF Research Database (Denmark)

    Schousboe, Inger; Nystrøm, Birthe

    2009-01-01

    High molecular weight kininogen (HK) is an abundant plasma protein that plays a central role for the function of the kallikrein/kinin/kininogen system. Thus, cleavage of HK by kallikrein liberates bradykinin, which stimulates vascular repair and a two-chain protein, activated HK (HKa), which indu...

  19. Impact modification of poly(caprolactam) by copolymerization with a low molecular weight polybutadiene

    NARCIS (Netherlands)

    Borggreve, R.J.M.; Gaymans, R.J.

    1988-01-01

    Caprolactam and a reactive, low molecular weight polybutadiene were polymerized in an autoclave, followed by post-condensation in the solid state. The rubber concentration was varied (0–30 wt%). The morphology of the reaction products was studied by transmission electron microscopy. In the materials

  20. From immune response to cancer : a spot on the low molecular weight protein tyrosine phosphatase

    NARCIS (Netherlands)

    Souza, A. C. S.; Azoubel, S.; Queiroz, K. C. S.; Peppelenbosch, M. P.; Ferreira, C. V.

    Reversible tyrosine phosphorylation is a key posttranslational regulatory modification of proteins in all eukaryotic cells in normal and pathological processes. Recently a pivotal janus-faced biological role of the low molecular weight protein tyrosine phosphatase (LMWPTP) has become clear. On the

  1. Exposure characterizations of polymer type electron beam resists with various molecular weights for next-generation photomask

    Science.gov (United States)

    Takayama, Tomohiro; Asada, Hironori; Kishimura, Yukiko; Hoshino, Ryoichi; Kawata, Atsushi

    2015-10-01

    Higher resolution is eagerly requested to the electron beam resist for the next generation photomask production as well as higher sensitivity. The performance of a polymer resist is mainly characterized by its chemical structure and molecular weight. Positive tone polymer resists with various molecular weights ranging from 60 k to 500 k are synthesized and the molecular weight dependence on exposure characteristics is examined by fabricating line-and-space patterns. The molecular weight dependence of sensitivity for amyl acetate developer is small in the molecular weight range in this study. In a low molecular weight resist, the cross-section profile of the resist pattern becomes rounder and then the disconnections are observed in the 20-nm line-and-space pattern. Although the pattern width change by changing the exposure dose for each resist is quite similar, the exposure dose margin of pattern formation becomes wider with the higher molecular weight. The line width roughness is smaller in a high molecular weight resist than in a low molecular weight resist. The shift amount of the pattern width from the design value for various line-and-space patterns and the dry etching resistance to CF4 plasma are also presented.

  2. Molecularly Imprinted Polymer Waveguides for Direct Optical Detection of Low-Molecular-Weight Analytes

    Czech Academy of Sciences Publication Activity Database

    Sharma, N.; Petri, C.; Jonas, U.; Bach, M.; Tovar, G.; Mrkvová, Kateřina; Vala, Milan; Homola, Jiří; Knoll, W.; Dostálek, J.

    2014-01-01

    Roč. 215, č. 23 (2014), s. 2295-2304 ISSN 1022-1352 R&D Projects: GA ČR GBP205/12/G118 Institutional support: RVO:67985882 Keywords : Label-free biosensors * Molecularly imprinted polymers * Hydrogels Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.616, year: 2014

  3. Detection of Diverse and High Molecular Weight Nesprin-1 and Nesprin-2 Isoforms Using Western Blotting.

    Science.gov (United States)

    Carthew, James; Karakesisoglou, Iakowos

    2016-01-01

    Heavily utilized in cell and molecular biology, western blotting is considered a crucial technique for the detection and quantification of proteins within complex mixtures. In particular, the detection of members of the nesprin (nuclear envelope spectrin repeat protein) family has proven difficult to analyze due to their substantial isoform diversity, molecular weight variation, and the sheer size of both nesprin-1 and nesprin-2 giant protein variants (>800 kDa). Nesprin isoforms contain distinct domain signatures, perform differential cytoskeletal associations, occupy different subcellular compartments, and vary in their tissue expression profiles. This structural and functional variance highlights the need to distinguish between the full range of proteins within the nesprin protein family, allowing for greater understanding of their specific roles in cell biology and disease. Herein, we describe a western blotting protocol modified for the detection of low to high molecular weight (50-1000 kDa) nesprin proteins.

  4. Weight Measurement Chitosan Molecule using GPC-MALLS

    International Nuclear Information System (INIS)

    Mohd Yusof Hamzah; Norhashidah Talip; Maznah Mahmud

    2011-01-01

    Research on basic characteristics and application of practical chitosan are need in order to understand their physical and chemical properties of this materials. One of the physico chemical properties that important for every polymers is absolute molecular weights. The important of this aspects has give big impacts on non colligative of the polymers, for example, viscosity, solubility and so on. Absolute weight molecular weights of each polymers can be measured by using GPC-MALLS. This device functioned as molecular size separator and molecular weight measurement by integration of the information such as sample concentration, light scattering index and sample reaction information using laser radiation irradiated from 18 angles.In this scope, we will discuss deeply on absolute weight molecular measurement of chitosan by using GPC-MALLS. (author)

  5. Hydrodynamic characterization and molecular weight estimation of ultrasonically sheared DNA; Caracterizacion hidrodinamica y estimacion de pesos moleculares de DNA degradado por ultrasonidos

    Energy Technology Data Exchange (ETDEWEB)

    Casal, J. I.; Garces, F.; Garcia-Sacristan, A.

    1981-07-01

    The sedimentation coefficients and intrinsic viscosities of ultrasonically sheared calf thymus DNA have been determined. The molecular weight estimation according to this parameters have been compared with the ones obtained from the electrophoretic migration rates based on the calibration proposed using the known molecular weight restriction fragments of X-ENA. (Author) 35 refs.

  6. Simultaneous ion removal and quantitation of low-molecular-weight dietary fiber from high-molecular-weight dietary fiber filtrates using liquid chromatography.

    Science.gov (United States)

    Post, Brett E; Marshak, Michael R; DeVries, Jonathan W

    2010-01-01

    Dietary fiber and its quantitation in foods have been of significant interest in the nutrition community for over 50 years. A number of AOAC Official Methods of Analysis have been adopted for the analysis of dietary fiber and some of its fractions and components commensurate with the evolving discoveries of dietary fiber nutrition research. Quantitation of low-molecular-weight soluble dietary fiber (LMWSDF) has been difficult due to high solubility in a precipitating solvent mixture of four parts alcohol and one part water. AOAC Method 2001.03 effectively quantitates LWMSDF subsequent to gravimetric removal of high-molecular-weight dietary fiber using LC. However, deionization and concentration of the enzymatic digestate, necessary to assure accurate LC quantitation, requires substantial time and manual labor. A modification to the method and resulting method performance is presented that describes a means of simultaneously deionizing the digestate and quantitating the LMWSDF in a single LC injection, eliminating a number of time-consuming manual preparation steps.

  7. Low molecular weight chitosan conjugated with folate for siRNA delivery in vitro: optimization studies

    Science.gov (United States)

    Fernandes, Julio C; Qiu, Xingping; Winnik, Francoise M; Benderdour, Mohamed; Zhang, Xiaoling; Dai, Kerong; Shi, Qin

    2012-01-01

    The low transfection efficiency of chitosan is one of its drawbacks as a gene delivery carrier. Low molecular weight chitosan may help to form small-sized polymer-DNA or small interfering RNA (siRNA) complexes. Folate conjugation may improve gene transfection efficiency because of the promoted uptake of folate receptor-bearing cells. In the present study, chitosan was conjugated with folate and investigated for its efficacy as a delivery vector for siRNA in vitro. We demonstrate that the molecular weight of chitosan has a major influence on its biological and physicochemical properties, and very low molecular weight chitosan (below 10 kDa) has difficulty in forming stable complexes with siRNA. In this study, chitosan 25 kDa and 50 kDa completely absorbed siRNA and formed nanoparticles (≤220 nm) at a chitosan to siRNA weight ratio of 50:1. The introduction of a folate ligand onto chitosan decreased nanoparticle toxicity. Compared with chitosan-siRNA, folate-chitosan-siRNA nanoparticles improved gene silencing transfection efficiency. Therefore, folate-chitosan shows potential as a viable candidate vector for safe and efficient siRNA delivery. PMID:23209368

  8. Cellular Viscosity in Prokaryotes and Thermal Stability of Low Molecular Weight Biomolecules.

    Science.gov (United States)

    Cuecas, Alba; Cruces, Jorge; Galisteo-López, Juan F; Peng, Xiaojun; Gonzalez, Juan M

    2016-08-23

    Some low molecular weight biomolecules, i.e., NAD(P)H, are unstable at high temperatures. The use of these biomolecules by thermophilic microorganisms has been scarcely analyzed. Herein, NADH stability has been studied at different temperatures and viscosities. NADH decay increased at increasing temperatures. At increasing viscosities, NADH decay rates decreased. Thus, maintaining relatively high cellular viscosity in cells could result in increased stability of low molecular weight biomolecules (i.e., NADH) at high temperatures, unlike what was previously deduced from studies in diluted water solutions. Cellular viscosity was determined using a fluorescent molecular rotor in various prokaryotes covering the range from 10 to 100°C. Some mesophiles showed the capability of changing cellular viscosity depending on growth temperature. Thermophiles and extreme thermophiles presented a relatively high cellular viscosity, suggesting this strategy as a reasonable mechanism to thrive under these high temperatures. Results substantiate the capability of thermophiles and extreme thermophiles (growth range 50-80°C) to stabilize and use generally considered unstable, universal low molecular weight biomolecules. In addition, this study represents a first report, to our knowledge, on cellular viscosity measurements in prokaryotes and it shows the dependency of prokaryotic cellular viscosity on species and growth temperature. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  9. Human skin penetration of hyaluronic acid of different molecular weights as probed by Raman spectroscopy.

    Science.gov (United States)

    Essendoubi, M; Gobinet, C; Reynaud, R; Angiboust, J F; Manfait, M; Piot, O

    2016-02-01

    Topical delivery of molecules into the human skin is one of the main issues in dermatology and cosmetology. Several techniques were developed to study molecules penetration into the human skin. Although widely accepted, the conventional methods such as Franz diffusion cells are unable to provide the accurate localization of actives in the skin layers. A different approach based on Raman spectroscopy has been proposed to follow-up the permeation of actives. It presents a high molecular specificity to distinguish exogenous molecules from skin constituents. Raman micro-imaging was applied to monitor the skin penetration of hyaluronic acids (HA) of different molecular weights. The first step, was the spectral characterization of these HA. After, we have determined spectral features of HA by which they can be detected in the skin. In the second part, transverse skin sections were realized and spectral images were recorded. Our results show a difference of skin permeation of the three HA. Indeed, HA with low molecular weight (20-300 kDa) passes through the stratum corneum in contrast of the impermeability of high molecular weight HA (1000-1400 kDa). Raman spectroscopy represents an analytical, non-destructive, and dynamic method to evaluate the permeation of actives in the skin layers. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Positive Family History, Infection, Low Absolute Lymphocyte Count (ALC), and Absent Thymic Shadow: Diagnostic Clues for All Molecular Forms of Severe Combined Immunodeficiency (SCID).

    Science.gov (United States)

    McWilliams, Laurie M; Dell Railey, Mary; Buckley, Rebecca H

    2015-01-01

    Severe combined immunodeficiency (SCID) is a syndrome uniformly fatal during infancy unless recognized and treated successfully by bone marrow transplantation or gene therapy. Because infants with SCID have no abnormal physical appearance, diagnosis is usually delayed unless newborn screening is performed. In this study, we sought to evaluate the presenting features of all 172 patients with SCID transplanted at this institution over the past 31 years. We reviewed original charts from 172 consecutive patients with classic SCID who received either T-cell-depleted HLA-haploidentical (N = 154) or HLA-identical (N = 18) nonablative related marrow transplants at Duke University Medical Center from 1982 to 2013. The mean age at presentation was 4.87 months. When there was a family history of early infant death or known SCID (37%), the mean presentation age was much earlier, 2.0 months compared with 6.6 months. Failure to thrive was common, with 84 patients (50%) having a weight less than the 5th percentile. The leading infections included oral moniliasis (43%), viral infections (35.5%), and Pneumocystis jiroveci (26%) pneumonia. The group mean absolute lymphocyte count (ALC) was 1454/cmm; 88% of the infants had an ALC less than 3000/cmm. An absent thymic shadow was seen in 92% of infants with electronic radiographic data available. An absence of T-cell function was found in all patients. Infants with SCID appear normal at birth but later present with failure to thrive and/or recurrent fungal, viral, and bacterial infections. Low ALCs and an absent thymic shadow on chest x-ray are key diagnostic clues. The absence of T-cell function confirms the diagnosis. Copyright © 2015 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  11. Nylon-6/rubber blends: 8. Influence of the molecular weight of the matrix on the impact behaviour

    NARCIS (Netherlands)

    Dijkstra, Krijn; Dijkstra, K.; Gaymans, R.J.

    1994-01-01

    Blends of nylon-6 with polybutadiene were prepared with comparable morphology and different molecular weights of the matrix. These specimens were tested using the notched Izod impact test and the notched tensile impact test. An increase in molecular weight resulted in a shift of the brittle-to-tough

  12. Effect of molecular weight and glass transition on relaxation and release behaviour of poly(DL-lactic acid) tablets

    NARCIS (Netherlands)

    Steendam, R.; Van Steenbergen, M.J.; Hennink, W.E.; Frijlink, H.W.; Lerk, C.F.

    2001-01-01

    Different molecular weight grades of poly(DL-lactic acid) were applied as release controlling excipients in tablets for oral drug administration. The role of molecular weight and glass transition in the mechanism of water-induced volume expansion and drug release of PDLA tablets was investigated.

  13. Effect of coagulant dosage on molecular weight of the rubber fractions allocated and vulcanizates physical-mechanical properties

    Directory of Open Access Journals (Sweden)

    I. N. Pugacheva

    2013-01-01

    Full Text Available The influence of dosage and nature of coagulation agents on molecular weight secreted butadiene-styrene rubber is considered. It is established that the increase of coagulant expense is accompanied by increase of molecular weight that is reflected in indicators received vulcanizates.

  14. Emulsifier-free emulsion polymerization of tetrafluoroethylene by radiation. IV. Effects of additives on Polymer molecular weight

    International Nuclear Information System (INIS)

    Watanabe, T.; Suwa, T.; Okamoto, J.; Machi, S.

    1979-01-01

    Poly(tetrafluoroethylene)(PTFE) of high molecular weight, 4.5 x 10 7 , was incidentally obtained at earlier study of an emulsifier-free emulsion polymerization of tetrafluoroethylene by radiation. In order to clarify this phenomenon, the effects of additives, in particular radical scavengers, on the molecular weight of PTFE and its polymerization behavior were studied. It was found that the molecular weight of PTFE is increased by the addition of hydroquinone, benzoquinone, α-pinene, dl-limonene, and ethylenediamine but is decreased by oxygen and triethylamine. A PTFE latex with molecular weight higher than 2 x 10 7 was obtained in the presence of hydroquinone. It is concluded that additives such as hydroquinone and benzaquinone, which rapidly scavenge the primary radicals (OH, H, and e/sub aq/ - ) in the aqueous phase but not the growing polymer radicals in PTFE particles, are most effective in increasing the molecular weight

  15. Effects of the matrix molecular weight on conductivity and dielectric relaxation in plasticized polyaniline/polymethylmethacrylathe blends

    Energy Technology Data Exchange (ETDEWEB)

    Fattoum, A; Gmati, F; Bohli, N; Mohamed, A Belhadj [Laboratoire de Semi Conducteur et Photovoltaique, Technopole Borj Cedria, BP 95, 2050 Hammam Lif (Tunisia); Arous, M [Laboratoire des Materiaux Composites Ceramiques et Polymeres, Faculte des Sciences de Sfax (Tunisia)], E-mail: arbi_fattoum@yahoo.fr

    2008-05-07

    We report the results of spectral, structural and electrical investigations on plasticized polyaniline/polymethylmethacrylate blend films (PAni/PMMA), obtained by the co-dissolution method using three different molecular weights of the PMMA matrix. The use of dibuthylphtalate as a plasticizer allowed us to obtain free standing thin films. The system showed percolation behaviour with an extremely low percolation threshold, independently of the PMMA molecular weight. The ac conductivity is well described by the universal Jonscher's law. By using the dielectric modulus, we have observed a dielectric relaxation assigned to the hopping of charge carriers (polarons and bipolarons) between localized states. The characteristic frequency of this relaxation follows an Arrhenius law and the activation energy depends on the PMMA molecular weight. This relaxation is well described by a simple Debye process for the lowest PMMA molecular weight and deviates from this model when the molecular weight of the PMMA increases.

  16. Phosphorus release from phosphate rock and iron phosphate by low-molecular-weight organic acids.

    Science.gov (United States)

    Xu, Ren-kou; Zhu, Yong-guan; Chittleborough, David

    2004-01-01

    Low-molecular-weight(LMW) organic acids widely exist in soils, particularly in the rhizosphere. A series of batch experiments were carried out to investigate the phosphorus release from rock phosphate and iron phosphate by low-molecular-weight organic acids. Results showed that citric acid had the highest capacity to solubilize P from both rock and iron phosphate. P solubilization from rock phosphate and iron phosphate resulted in net proton consumption. P release from rock phosphate was positively correlated with the pKa values. P release from iron phosphate was positively correlated with Fe-organic acid stability constants except for aromatic acids, but was notcorrelated with pKa. Increase in the concentrations of organic acids enhanced P solubilization from both rock and iron phosphate almost linearly. Addition of phenolic compounds further increased the P release from iron phosphate. Initial solution pH had much more substantial effect on P release from rock phosphate than from iron phosphate.

  17. Venous thromboembolism in pregnancy: prophylaxis and treatment with low molecular weight heparin

    DEFF Research Database (Denmark)

    Andersen, Anita Sylvest; Berthelsen, Jørgen G.; Bergholt, Thomas

    2010-01-01

    OBJECTIVE: To evaluate the safety of individually dosed low molecular weight heparin (LMWH) for prophylaxis and treatment of thromboembolic complications in pregnancy. DESIGN: Cohort study with a chronologic register-based control group. SETTING: Department of Obstetrics and Gynecology, Hiller...... were in good health at discharge. CONCLUSIONS: Individually dosed LMWH is well tolerated and safe for prophylaxis and treatment of thromboembolic complications during pregnancy, delivery and the postpartum periodOBJECTIVE: To evaluate the safety of individually dosed low molecular weight heparin (LMWH......) for prophylaxis and treatment of thromboembolic complications in pregnancy. DESIGN: Cohort study with a chronologic register-based control group. SETTING: Department of Obstetrics and Gynecology, Hillerød Hospital, Denmark. POPULATION: All 166 women treated with LMWH in pregnancy between 1 January 2001 and 31...

  18. Managing cancer-related venous thromboembolic disease: low-molecular-weight heparins and beyond.

    Science.gov (United States)

    O'Connell, Casey L; Liebman, Howard A

    2008-12-01

    Venous thromboembolism is a major contributor to the morbidity and mortality of patients with cancer. For patients undergoing cancer surgery, several trials support the safety and efficacy of unfractionated heparin and of low-molecular-weight heparin for the prevention of venous thromboembolism, while data regarding the efficacy and safety of these agents in the setting of medical hospitalization is less definitive and must be extracted from trials including noncancer patients with different thrombotic risk factors. Randomized clinical studies confirm that patients with cancer who develop venous thromboembolism have superior outcomes when treated with long-term low-molecular-weight heparin as compared with warfarin. Novel anticoagulants that are orally bioavailable and function by directly inhibiting factor Xa or thrombin are entering the market. To date, data regarding the efficacy and safety of these novel anticoagulants as venous thromboembolism prophylaxis and treatment in cancer patients are not available and must be extracted from larger trials with heterogeneous patient populations.

  19. Preparation of the low molecular weight serum proteome for mass spectrometry analysis.

    Science.gov (United States)

    Waybright, Timothy J; Chan, King C; Veenstra, Timothy D; Xiao, Zhen

    2013-01-01

    The discovery of viable biomarkers or indicators of disease states is complicated by the inherent complexity of the chosen biological specimen. Every sample, whether it is serum, plasma, urine, tissue, cells, or a host of others, contains thousands of large and small components, each interacting in multiple ways. The need to concentrate on a group of these components to narrow the focus on a potential biomarker candidate becomes, out of necessity, a priority, especially in the search for immune-related low molecular weight serum biomarkers. One such method in the field of proteomics is to divide the sample proteome into groups based on the size of the protein, analyze each group, and mine the data for statistically significant items. This chapter details a portion of this method, concentrating on a method for fractionating and analyzing the low molecular weight proteome of human serum.

  20. Role of Laccase and Low Molecular Weight Metabolites from Trametes versicolor in Dye Decolorization

    Directory of Open Access Journals (Sweden)

    Diego Moldes

    2012-01-01

    Full Text Available The studies regarding decolorization of dyes by laccase may not only inform about the possible application of this enzyme for environmental purposes, but also may provide important information about its reaction mechanism and the influence of several factors that could be involved. In this paper, decolorization of crystal violet and phenol red was carried out with different fractions of extracellular liquids from Trametes versicolor cultures, in order to describe the role of laccase in this reaction. Moreover, the possible role of the low molecular weight metabolites (LMWMs also produced by the fungus was evaluated. The results confirm the existence of a nonenzymatic decolorization factor, since the nonprotein fraction of the extracellular liquids from cultures of T. versicolor has shown decolorization capability. Several experiments were performed in order to identify the main compounds related to this ability, which are probably low molecular weight peroxide compounds.

  1. Chemical modification of high molecular weight polyethylene through gamma radiation for biomaterials applications

    International Nuclear Information System (INIS)

    Raposo, Matheus P.; Rocha, Marisa C.G.

    2015-01-01

    Ultra high molecular weight polyethylene has been used in the medical field due to its high mechanical properties compared to the other polymers. Its main application is in the development of orthopedic implants, which requires high resistance to abrasion. One of the most used methods is the introduction of crosslinks in the polymer through gamma irradiation. In order to prevent oxidation reactions, studies have been developed using tacoferol (vitamin E) as an antioxidant for the material. The ascorbic acid (vitamin C), however, has been appointed as a viable alternative for vitamin E. In this work, a high molecular weight polyethylene grade (HMWPE) and polyethylene samples formulated with vitamin C were submitted to gamma radiation. Thermodynamic-mechanical methods and gel content determinations were used to characterize the samples obtained. The sample containing 1% of vitamin C and irradiated with 50 KGy of gamma radiation presented the highest content of crosslinks. (author)

  2. Role of laccase and low molecular weight metabolites from Trametes versicolor in dye decolorization.

    Science.gov (United States)

    Moldes, Diego; Fernández-Fernández, María; Sanromán, M Ángeles

    2012-01-01

    The studies regarding decolorization of dyes by laccase may not only inform about the possible application of this enzyme for environmental purposes, but also may provide important information about its reaction mechanism and the influence of several factors that could be involved. In this paper, decolorization of crystal violet and phenol red was carried out with different fractions of extracellular liquids from Trametes versicolor cultures, in order to describe the role of laccase in this reaction. Moreover, the possible role of the low molecular weight metabolites (LMWMs) also produced by the fungus was evaluated. The results confirm the existence of a nonenzymatic decolorization factor, since the nonprotein fraction of the extracellular liquids from cultures of T. versicolor has shown decolorization capability. Several experiments were performed in order to identify the main compounds related to this ability, which are probably low molecular weight peroxide compounds.

  3. Simulated dynamic response of a multi-stage compressor with variable molecular weight flow medium

    Science.gov (United States)

    Babcock, Dale A.

    1995-01-01

    A mathematical model of a multi-stage compressor with variable molecular weight flow medium is derived. The modeled system consists of a five stage, six cylinder, double acting, piston type compressor. Each stage is followed by a water cooled heat exchanger which serves to transfer the heat of compression from the gas. A high molecular weight gas (CFC-12) mixed with air in varying proportions is introduced to the suction of the compressor. Condensation of the heavy gas may occur in the upper stage heat exchangers. The state equations for the system are integrated using the Advanced Continuous Simulation Language (ACSL) for determining the system's dynamic and steady state characteristics under varying operating conditions.

  4. Higher molecular weight dissolved organic nitrogen turnover as affected by soil management history

    DEFF Research Database (Denmark)

    Lønne Enggrob, Kirsten

    High molecular weight dissolved organic nitrogen turnover as affected by soil management history *Kirsten Lønne Enggrob,1 Lars Elsgaard,1 and Jim Rasmussen1 1Aarhus University, Dept. of Agroecology, Foulum, Denmark 1. Introduction Dissolved organic nitrogen (DON) play an important role in soil N...... cycling. DON, as a collective term, refers to a diversity of organic N compounds which can operationally be grouped into high molecular weight (Mw) DON (Mw > 1 kDa) and low Mw DON (... of different management histories on the turnover of high Mw DON. Further, we distinguished between several classes of high Mw DON, i.e., 1-10 kDa and >10 kDa. 3. Materials and methods With the use of micro-lysimeters, the turnover of triple-labeled (15N, 14C and 13C) high Mw DON was studied in a sandy soil...

  5. Extraction of high-molecular-weight genomic DNA for long-read sequencing of single molecules.

    Science.gov (United States)

    Mayjonade, Baptiste; Gouzy, Jérôme; Donnadieu, Cécile; Pouilly, Nicolas; Marande, William; Callot, Caroline; Langlade, Nicolas; Muños, Stéphane

    2016-10-01

    De novo sequencing of complex genomes is one of the main challenges for researchers seeking high-quality reference sequences. Many de novo assemblies are based on short reads, producing fragmented genome sequences. Third-generation sequencing, with read lengths >10 kb, will improve the assembly of complex genomes, but these techniques require high-molecular-weight genomic DNA (gDNA), and gDNA extraction protocols used for obtaining smaller fragments for short-read sequencing are not suitable for this purpose. Methods of preparing gDNA for bacterial artificial chromosome (BAC) libraries could be adapted, but these approaches are time-consuming, and commercial kits for these methods are expensive. Here, we present a protocol for rapid, inexpensive extraction of high-molecular-weight gDNA from bacteria, plants, and animals. Our technique was validated using sunflower leaf samples, producing a mean read length of 12.6 kb and a maximum read length of 80 kb.

  6. High molecular weight bioemulsifiers, main properties and potential environmental and biomedical applications.

    Science.gov (United States)

    Mnif, Inès; Ghribi, Dhouha

    2015-05-01

    High molecular weight bioemulsifiers are amphipathic polysaccharides, proteins, lipopolysaccharides, lipoproteins, or complex mixtures of these biopolymers, produced by a wide variety of microorganisms. They are characterized by highly structural diversity and have the ability to decrease the surface and interfacial tension at the surface and interface respectively and/or emulsify hydrophobic compounds. Emulsan, fatty acids, phospholipids, neutral lipids, exopolysaccharides, vesicles and fimbriae are among the most popular high molecular weight bioemulsifiers. They have great physic-chemical properties like tolerance to extreme conditions of pH, temperature and salinity, low toxicity and biodegradability. Owing their emulsion forming and breaking capacities, solubilization, mobilization and dispersion activities and their viscosity reduction activity; they possess great environmental application as enhancer of hydrocarbon biodegradation and for microbial enhanced oil recovery. Besides, they are applied in biomedical fields for their antimicrobial and anti-adhesive activities and involvement in immune responses.

  7. Venous thromboembolism in pregnancy: prophylaxis and treatment with low molecular weight heparin

    DEFF Research Database (Denmark)

    Andersen, Anita Sylvest; Berthelsen, Jørgen G.; Bergholt, Thomas

    2010-01-01

    OBJECTIVE: To evaluate the safety of individually dosed low molecular weight heparin (LMWH) for prophylaxis and treatment of thromboembolic complications in pregnancy. DESIGN: Cohort study with a chronologic register-based control group. SETTING: Department of Obstetrics and Gynecology, Hiller...... side effects of treatment and no osteoporotic fractures or episodes of heparin-induced thrombocytopenia. The 166 pregnancies resulted in 159 live infants. There was a significantly higher risk of preterm delivery (13% vs. 6%) and intrauterine growth restriction (4.4% vs. 3.5%). Delivery by cesarean...... were in good health at discharge. CONCLUSIONS: Individually dosed LMWH is well tolerated and safe for prophylaxis and treatment of thromboembolic complications during pregnancy, delivery and the postpartum periodOBJECTIVE: To evaluate the safety of individually dosed low molecular weight heparin (LMWH...

  8. Participation of Low Molecular Weight Electron Carriers in Oxidative Protein Folding

    Directory of Open Access Journals (Sweden)

    József Mandl

    2009-03-01

    Full Text Available Oxidative protein folding is mediated by a proteinaceous electron relay system, in which the concerted action of protein disulfide isomerase and Ero1 delivers the electrons from thiol groups to the final acceptor. Oxygen appears to be the final oxidant in aerobic living organisms, although the existence of alternative electron acceptors, e.g. fumarate or nitrate, cannot be excluded. Whilst the protein components of the system are well-known, less attention has been turned to the role of low molecular weight electron carriers in the process. The function of ascorbate, tocopherol and vitamin K has been raised recently. In vitro and in vivo evidence suggests that these redox-active compounds can contribute to the functioning of oxidative folding. This review focuses on the participation of small molecular weight redox compounds in oxidative protein folding.

  9. High molecular weight DNA assembly in vivo for synthetic biology applications.

    Science.gov (United States)

    Juhas, Mario; Ajioka, James W

    2017-05-01

    DNA assembly is the key technology of the emerging interdisciplinary field of synthetic biology. While the assembly of smaller DNA fragments is usually performed in vitro, high molecular weight DNA molecules are assembled in vivo via homologous recombination in the host cell. Escherichia coli, Bacillus subtilis and Saccharomyces cerevisiae are the main hosts used for DNA assembly in vivo. Progress in DNA assembly over the last few years has paved the way for the construction of whole genomes. This review provides an update on recent synthetic biology advances with particular emphasis on high molecular weight DNA assembly in vivo in E. coli, B. subtilis and S. cerevisiae. Special attention is paid to the assembly of whole genomes, such as those of the first synthetic cell, synthetic yeast and minimal genomes.

  10. Lunch-time food choices in preschoolers: relationships between absolute and relative intake of different food categories, and appetitive characteristics and weight

    OpenAIRE

    Carnell, S; Pryor, K; Mais, LA; Warkentin, S; Benson, L; Cheng, R

    2016-01-01

    Children’s appetitive characteristics measured by parent-report questionnaires are reliably associated with body weight, as well as behavioral tests of appetite, but relatively little is known about relationships with food choice. As part of a larger preloading study, we served 4-5y olds from primary school classes five school lunches at which they were presented with the same standardized multi-item meal. Parents completed Child Eating Behavior Questionnaire (CEBQ) sub-scales assessing satie...

  11. Effects of cross-linking molecular weights in a hyaluronic acid-poly(ethylene oxide) hydrogel network on its properties

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Insup [Department of Chemical Engineering, Seoul National University of Technology, 172 Gongnung-dong, Nowon-gu, Seoul 139-743 (Korea, Republic of); Kim, Gun-Woo [Department of Chemical Engineering, Seoul National University of Technology, 172 Gongnung-dong, Nowon-gu, Seoul 139-743 (Korea, Republic of); Choi, Yoon-Jeong [Department of Chemical Engineering, Seoul National University of Technology, 172 Gongnung-dong, Nowon-gu, Seoul 139-743 (Korea, Republic of); Kim, Mi-Sook [Department of Chemical Engineering, Seoul National University of Technology, 172 Gongnung-dong, Nowon-gu, Seoul 139-743 (Korea, Republic of); Park, Yongdoo [Korea Artificial Organ Center, Korea University, Seoul 136-705 (Korea, Republic of); Lee, Kyu-Back [Korea Artificial Organ Center, Korea University, Seoul 136-705 (Korea, Republic of); Kim, In-Sook [Dental Research Institute, Seoul National University, Seoul 110-749 (Korea, Republic of); Hwang, Soon-Jung [Dental Research Institute, Seoul National University, Seoul 110-749 (Korea, Republic of); Tae, Giyoong [Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

    2006-09-15

    We examined the effects of cross-linking molecular weights on the properties of a hyaluronic acid (HA)-poly(ethylene oxide) (PEO) hydrogel. Swelling behaviors, mechanical strength and rheological behaviors of the HA-PEO hydrogel were evaluated by employing different cross-linking molecular weights (100 kDa and 1.63 mDa) of the HAs in the hydrogel networks. The low molecular weight of HA was obtained in advance by treating high molecular weight HA with a hydrogen chloride solution. Methacrylation of HA was obtained by grafting aminopropylmethacrylate to its caroboxylic acid functional groups. While reduction of the HA molecular weights was confirmed by gel permeation chromatography, the degree of methacrylate grafting to the HA was measured by {sup 1}H-nuclear magnetic resonance. Synthesis of the HA-PEO hydrogel was successfully achieved via the Michael-type addition reaction between the methacrylate arm groups in the HA and the six thiol groups in PEO. The hydrogel formation was not dependent upon the HA molecular weights and its gelation behaviors were markedly different. Compared to the properties of the high molecular weight HA-based PEO one, the low molecular weight HA-based hydrogel induced quicker hydrogelation, as observed from the behaviors of the elastic and viscous modulus. Furthermore, the low molecular weight HA-based hydrogel demonstrated stronger mechanical properties as measured with a texture analyzer, lower water absorption as measured with a microbalance and smaller pore sizes on its surface and cross section as observed with scanning electron microscopy. The information about the effects of the cross-linking molecular weights of the gel network on the properties of the HA-based PEO hydrogel may lead to better design of hydrogels, especially in tissue engineering applications.

  12. Novel Stabilisers Acting Simultaneously as Molecular-Weight Regulators in Soluble Elastomeric Polyurethanes

    Czech Academy of Sciences Publication Activity Database

    Hetflejš, Jiří; Šabata, Stanislav; Podešva, Jiří; Kovářová, Jana; Prokůpek, L.; Netopilík, Miloš; Spěváček, Jiří; Sýkora, Jan

    2010-01-01

    Roč. 95, č. 4 (2010), s. 579-586 ISSN 0141-3910 R&D Projects: GA ČR GA203/07/0987; GA AV ČR IAA400720706 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40500505 Keywords : stabilisers * molecular-weight regulators * elastomeric polyurethanes Subject RIV: CC - Organic Chemistry Impact factor: 2.594, year: 2010

  13. Silver Nanoparticles Modification of Ultra High Molecular Weight Polyethylene in Non-Aqueous Medium

    OpenAIRE

    V. N. Glushko; L. I. Blokhina; E. E. Anisimova; M. V. Bogdanovskaya; V. I. Kozhukhov; T. A. Cherdyntseva

    2016-01-01

    A series of experiments for obtaining modified with silver nanoparticles ultra-high molecular weight polyethylene (UHMWPE) is done. Optimal precursors are silver trifluoroacetate, silver nitrate and silver methanesulfonate. Three variants of UHMWPE modification is studied: 1) the polyol synthesis, 2) polymer processing silver nanoparticle colloid and 3) reduction of silver salt solution in the UHMWPE polymer matrix. It is found that the last method is optimal. The specific surface of obtained...

  14. Effect of Molecular Weight on the Thermal and Spectroscopic Properties of Poly(vinyl alcohol) Films

    International Nuclear Information System (INIS)

    Khafagy, R.M.; Abd El-Kader, K.M.; Badr, Y.A.

    2009-01-01

    Thin films of Poly(vinyl alcohol) (PVA) with molecular weights 5000, 17000,72000 and 125000 g/mol were prepared by casting technique.Samples were thermally and spectroscopically investigated using TGA, DSC, FTIR and FT-Raman spectroscopy, in order to show how the thermal stability and structure of PVA might be correlated with its molecular weight. Thermal analysis showed that samples degrade in two steps mechanism. The mechanism observed for degradation in an inert atmosphere was in accordance with the accepted mechanism of elimination followed by pyrolisation. PVA 5000MW and PVA 17000Mw showed almost similar thermal behavior due to their expected similar structure. PVA 72000Mw showed lower thermal stability since it is characterized with the presence of the unstable C-O-C ether linkages, which lead to the fast melting of this sample. PVA 125000Mw showed the highest thermal stability because crosslinking of the main chains takes place due to introducing additional PVA units, which substitute each over oxygen atom. ΔH values obtained from DSC showed good accordance with TGA and Drtg analysis. Moreover, FTIR and FT-Raman results agreed well with thermal analysis, and confirmed our supposed structural changes which might take place as the molecular weight of the sample changes: since the water uptake, presence of ether linkages, and double bonds formulation due to crosslinking, were confirmed with FTIR and FT-Raman spectral analysis. The crystallinity percentage of the samples was calculated from Raman spectra and results confirmed our spectroscopic explanations. The thermal and spectroscopic behavior of the samples was explained as a result of the competitive action of at least three factors due to increasing the molecular weight: (i) diminution of the existing physical network due to changes in hydrogen bonding; (ii) formation of a chemical network; and (iii) introduction of flexible moieties due to the specific chemical structure after crosslinking

  15. Effect of molecular weight on hydrogen--deuterium exchange in a nonhelical polyamide

    International Nuclear Information System (INIS)

    Snyder, W.D.; Klotz, I.M.

    1975-01-01

    Hydrogen--deuterium exchange kinetics were measured for poly(isopropylacrylamides) over a molecular weight range from 100 to 200,000. A sharp drop in rate appears as soon as one goes from monomer to trimer. Thereafter a very slow progressive decrease is displayed. The local environment of the exchanging amide residue is largely (although not completely) established by the mutual interaction of as few as three residues in these polymers of random conformation. (U.S.)

  16. A low molecular weight urinary proteome profile of human kidney aging

    OpenAIRE

    Zürbig, Petra; Decramer, Stéphane; Dakna, Mohammed; Jantos, Justyna; Good, David M.; Coon, Joshua J.; Bandin, Flavio; Mischak, Harald; Bascands, Jean-Loup; Schanstra, Joost P

    2009-01-01

    Aging induces morphological changes of the kidney and reduces renal function. We analyzed the low molecular weight urinary proteome of 324 healthy individuals from 2-73 years of age to gain insight on renal aging in humans. We observed age-related modification of secretion of 325 out of 5000 urinary peptides. The majority of these changes was associated with renal development before and during puberty, while 49 peptides were related to aging in adults. Of these 49 peptides, the majority were ...

  17. A Simple Thermoplastic Substrate Containing Hierarchical Silica Lamellae for High-Molecular-Weight DNA Extraction.

    Science.gov (United States)

    Zhang, Ye; Zhang, Yi; Burke, Jeffrey M; Gleitsman, Kristin; Friedrich, Sarah M; Liu, Kelvin J; Wang, Tza-Huei

    2016-12-01

    An inexpensive, magnetic thermoplastic nanomaterial is developed utilizing a hierarchical layering of micro- and nanoscale silica lamellae to create a high-surface-area and low-shear substrate capable of capturing vast amounts of ultrahigh-molecular-weight DNA. Extraction is performed via a simple 45 min process and is capable of achieving binding capacities up to 1 000 000 times greater than silica microparticles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Urinary high molecular weight matrix metalloproteinases as non-invasive biomarker for detection of bladder cancer

    OpenAIRE

    Mohammed, Mohammed A; Seleim, Manar F; Abdalla, Mohga S; Sharada, Hayat M; Abdel Wahab, Abdel Hady A

    2013-01-01

    Background Matrix Metalloproteinases (MMPs) are key molecules for tumor growth, invasion and metastasis. Over-expression of different MMPs in tumor tissues can disturb the homeostasis and increase the level of various body fluids. Many MMPs including high molecular weights (HMWs) were detected in the urine of prostate and bladder cancer patients. Our aim here is to assess the usefulness of HMW MMPs as non invasive biomarkers in bilharzial bladder cancer in Egyptian patients. Methods The activ...

  19. A versatile electrophoresis system for the analysis of high- and low-molecular-weight proteins.

    OpenAIRE

    Tastet, Christophe; Lescuyer, Pierre; Diemer, Hélène; Luche, Sylvie; Van Dorsselaer, Alain; Rabilloud, Thierry

    2003-01-01

    website publisher www.interscience.wiley.com; International audience; A new, versatile, multiphasic buffer system for high-resolution sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins in the relative molecular weight range of 300 000-3000 Da is described. The system, based on the theory of multiphasic zone electrophoresis, allows complete stacking and destacking of proteins in the above M(r) range. The buffer system uses taurine and chloride as trailing and leading ion, re...

  20. Study the Effect of Imposing Surfactants toward the Evaporation of Low Molecular Weight Alcohol

    OpenAIRE

    Mohammad , H.H.; Sharifuddin Md. , Zain; Rashid Atta , Khan; Khalisanni , Khalid

    2013-01-01

    International audience; In this paper, Reversed-Flow Gas Chromatography (RF-GC) is utilized to investigate the evaporation of low molecular weight alcohol. Evaporation rates as well as the diffusion rates of methanol are determined with a surfactant monolayer on the surface of the liquid; while nitrogen acts as carrier gas, at 313 K. The precision (>99.9%) and accuracy of this investigation demonstrates the potential of current methodologies for environmental impact studies; this is further v...

  1. Study the Effect of Imposing Surfactants toward the Evaporation of Low Molecular Weight Alcohol

    OpenAIRE

    H.H., Mohammad; Zain, Sharifuddin Mohd; Khan, Rashid Atta; Khalid, Khalisanni

    2017-01-01

    In this paper, Reversed-Flow Gas Chromatography (RF-GC) is utilized to investigate the evaporation of low molecular weight alcohol. Evaporation rates as well as the diffusion rates of methanol are determined with a surfactant monolayer on the surface of the liquid; while nitrogen acts as carrier gas, at 313 K. The precision (>99.9%) and accuracy of this investigation demonstrates the potential of current methodologies for environmental impact studies; this is further verified when the results...

  2. Determination of dextrose equivalent value and number average molecular weight of maltodextrin by osmometry.

    Science.gov (United States)

    Rong, Y; Sillick, M; Gregson, C M

    2009-01-01

    Dextrose equivalent (DE) value is the most common parameter used to characterize the molecular weight of maltodextrins. Its theoretical value is inversely proportional to number average molecular weight (M(n)), providing a theoretical basis for correlations with physical properties important to food manufacturing, such as: hygroscopicity, the glass transition temperature, and colligative properties. The use of freezing point osmometry to measure DE and M(n) was assessed. Measurements were made on a homologous series of malto-oligomers as well as a variety of commercially available maltodextrin products with DE values ranging from 5 to 18. Results on malto-oligomer samples confirmed that freezing point osmometry provided a linear response with number average molecular weight. However, noncarbohydrate species in some commercial maltodextrin products were found to be in high enough concentration to interfere appreciably with DE measurement. Energy dispersive spectroscopy showed that sodium and chloride were the major ions present in most commercial samples. Osmolality was successfully corrected using conductivity measurements to estimate ion concentrations. The conductivity correction factor appeared to be dependent on the concentration of maltodextrin. Equations were developed to calculate corrected values of DE and M(n) based on measurements of osmolality, conductivity, and maltodextrin concentration. This study builds upon previously reported results through the identification of the major interfering ions and provides an osmolality correction factor that successfully accounts for the influence of maltodextrin concentration on the conductivity measurement. The resulting technique was found to be rapid, robust, and required no reagents.

  3. Simple Extraction and Molecular Weight Characterization of Fucoidan from Indonesian Sargassum sp.

    Directory of Open Access Journals (Sweden)

    Lukman Junaidi

    2013-12-01

    Full Text Available Fucoidan is a complex polysaccharide compounds found in brown algae. Fucoidan exhibits various biological properties for disease prevention. There are various methods used to extract fucoidan from brown algae, such as using ethanol, acetone, HCl and microwave. This research aims to extract and characterize fucoidan from Sargassum sp. using simple methods with the variables on extracting solutions, temperature and time of extraction. Extraction solution used were water and HCl. Ttemperature used was 50°C, 70°C and 100°C  using 1, 2 and 4 hours. The result showed that the highest extraction yield was obtained from the extraction by water with 100°C and 4 hours of extraction. Fucoidan extracted by water has molecular weight of 57.77 kDa and 2.71 kDa, while fucoidan extracted by HCl has molecular weight of 46.43 kDa and 3.38 kDa. The proportion of high molecular weight fucoidan extracted by water was 52.24% compared with HCl was 44.10%.

  4. Synthesis of High-Molecular-Weight Polyhydroxyalkanoates by Marine Photosynthetic Purple Bacteria.

    Directory of Open Access Journals (Sweden)

    Mieko Higuchi-Takeuchi

    Full Text Available Polyhydroxyalkanoate (PHA is a biopolyester/bioplastic that is produced by a variety of microorganisms to store carbon and increase reducing redox potential. Photosynthetic bacteria convert carbon dioxide into organic compounds using light energy and are known to accumulate PHA. We analyzed PHAs synthesized by 3 purple sulfur bacteria and 9 purple non-sulfur bacteria strains. These 12 purple bacteria were cultured in nitrogen-limited medium containing acetate and/or sodium bicarbonate as carbon sources. PHA production in the purple sulfur bacteria was induced by nitrogen-limited conditions. Purple non-sulfur bacteria accumulated PHA even under normal growth conditions, and PHA production in 3 strains was enhanced by nitrogen-limited conditions. Gel permeation chromatography analysis revealed that 5 photosynthetic purple bacteria synthesized high-molecular-weight PHAs, which are useful for industrial applications. Quantitative reverse transcription polymerase chain reaction analysis revealed that mRNA levels of phaC and PhaZ genes were low under nitrogen-limited conditions, resulting in production of high-molecular-weight PHAs. We conclude that all 12 tested strains are able to synthesize PHA to some degree, and we identify 5 photosynthetic purple bacteria that accumulate high-molecular-weight PHA molecules. Furthermore, the photosynthetic purple bacteria synthesized PHA when they were cultured in seawater supplemented with acetate. The photosynthetic purple bacteria strains characterized in this study should be useful as host microorganisms for large-scale PHA production utilizing abundant marine resources and carbon dioxide.

  5. Molecular weight dependent structure and charge transport in MAPLE-deposited poly(3-hexylthiophene) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Ban Xuan [Department of Materials Science and Engineering, Biointerfaces Institute, University of Michigan, Ann Arbor Michigan 48109; Smith, Mitchell [Department of Chemistry, University of Michigan, Ann Arbor Michigan 48109; Strzalka, Joseph [X-Ray Science Division, Argonne National Laboratory, Argonne Illinois 60439; Li, Huanghe [Macromolecular Science and Engineering, University of Michigan, Ann Arbor Michigan 48109; McNeil, Anne J. [Department of Chemistry, University of Michigan, Ann Arbor Michigan 48109; Macromolecular Science and Engineering, University of Michigan, Ann Arbor Michigan 48109; Stein, Gila E. [Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville Tennessee 37996; Green, Peter F. [Department of Materials Science and Engineering, Biointerfaces Institute, University of Michigan, Ann Arbor Michigan 48109; Macromolecular Science and Engineering, University of Michigan, Ann Arbor Michigan 48109; National Renewable Energy Laboratory, 15013 Denver W Pkwy, Golden Colorado 80401

    2018-02-06

    In this work, poly(3-hexylthiophene) (P3HT) films prepared using the matrix-assisted pulsed laser evaporation (MAPLE) technique are shown to possess morphological structures that are dependent on molecular weight (MW). Specifically, the structures of low MW samples of MAPLE-deposited film are composed of crystallites/aggregates embedded within highly disordered environments, whereas those of high MW samples are composed of aggregated domains connected by long polymer chains. Additionally, the crystallite size along the side-chain (100) direction decreases, whereas the conjugation length increases with increasing molecular weight. This is qualitatively similar to the structure of spin-cast films, though the MAPLE-deposited films are more disordered. In-plane carrier mobilities in the MAPLE-deposited samples increase with MW, consistent with the notion that longer chains bridge adjacent aggregated domains thereby facilitating more effective charge transport. The carrier mobilities in the MAPLE-deposited simples are consistently lower than those in the solvent-cast samples for all molecular weights, consistent with the shorter conjugation length in samples prepared by this deposition technique.

  6. Molecular Weight and Charge Density Effects of Guanidinylated Biodegradable Polycarbonates on Antimicrobial Activity and Selectivity.

    Science.gov (United States)

    Hae Cho, Chloe A; Liang, Chao; Perera, Janesha; Liu, Jie; Varnava, Kyriakos G; Sarojini, Vijayalekshmi; Cooney, Ralph P; McGillivray, Duncan J; Brimble, Margaret A; Swift, Simon; Jin, Jianyong

    2017-11-21

    Six guanidine functionalized aliphatic biodegradable polycarbonates with varying molecular weights and charge densities were synthesized via postsynthesis modification of alkyne containing polycarbonates using Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click chemistry. The concept of passive diluting group was to modify the cationic charge density of the polycarbonate without changing its hydrophilicity. Within the molecular weight range from 8000 to 30000 g mol -1 , these guanidine polycarbonates exhibited broad-spectrum biocidal activity with low toxicity to red blood cells (RBCs). The lowest molecular weight homopolymer sample (PG-8k-100) showed the best antimicrobial activity (MIC = 40 μg/mL against Escherichia coli and MIC = 20 μg/mL against Staphylococcus epidermidis) and least RBC toxicity (0.6% hemolysis at MIC). Within the three guanidine charge densities from 20% to 70%, the low to medium dilution samples (PG-8k-7030 and PG-8k-5050) had no obvious loss in antimicrobial activities compared to the nondiluted control sample PG-8k-100. However, upon further dilution, PG-8k-2080 gave the lowest antimicrobial activity.

  7. Update on the clinical use of the low-molecular-weight heparin, parnaparin

    Directory of Open Access Journals (Sweden)

    Giuseppe Camporese

    2009-09-01

    Full Text Available Giuseppe Camporese1, Enrico Bernardi2, Franco Noventa31Unit of Angiology and 3Department of Clinical and Experimental Medicine, Clinical Epidemiology Group, University Hospital of Padua, Italy; 2Department of Emergency and Accident Medicine, Hospital of Conegliano Veneto, ItalyAbstract: Parnaparin is a low-molecular-weight heparin that has widely shown its efficacy and safety in prevention of venous thromboembolism, in the treatment of chronic venous disorders, and in the treatment of venous and arterial (stable and unstable angina, acute ST-segment elevation myocardial infarction thrombosis. Parnaparin at the respective dosages of 3200, 4250, 6400, or 12800 IUaXa for a period ranging from 3 to 5 days to 6 months, is usually administered subcutaneously by means of once-daily regimen and is better tolerated than unfractionated heparin at the injection site. In the variety of commercially available low-molecular-weight heparins, parnaparin represents a useful therapeutic option, even though little evidence is available comparing the superiority or the equivalent efficacy and safety of parnaparin to that of the unfractionated heparin or placebo. This review summarizes the available literature on the use of parnaparin in different settings of cardiovascular diseases, including papers published during the past year and ongoing studies.Keywords: low-molecular-weight heparin, heparin, parnaparin, acute coronary syndromes, venous thromboembolism

  8. Lab-on-a-Chip method uncertanties in determination of high-molecular-weight glutenin subunits

    Directory of Open Access Journals (Sweden)

    Živančev Dragan R.

    2013-01-01

    Full Text Available Polymeric wheat endosperm proteins, especially the high-molecular-weight glutenin subunits (HMW-GS, are probably the most interesting protein fraction giving the essential information about bread-making quality of wheat flour. A relatively new method that shows a great potential for a fast, reliable and automatable analysis of protein purity, sizing and quantification is microfluidic or Lab-on-a-Chip (LoaC capillary electrophoresis. This work was aimed to explore the possibilities of implementation of LoaC method to analysis of protein samples isolated from a Serbian common wheat variety, emphasizing the steps that might bring uncertainties and affect reproducibility of obtained glutenin subunits quantitation results. A good resolution of protein bands in a molecular weight range of 14.0 to 220.0 kDa was achieved. The reproducibility of HMW-GS sizing and quantitation were good, with the average coefficient of variation values of 1.2% and 12.2%. The ratio of HMW-GS to low-molecular-weight glutenin subunits (LMW-GS was about 20%. The investigation ruled out influences of the extract solution addition and the buffer addition steps of the applied method, as well as the individual chip influence on GS quantitation results. However, there was statistically significant difference between HMW-GS quantitation results of multi-step and one-step extraction procedures applied prior to glutenin subunits extraction step.

  9. Antibacterial effects of chitosan-tripolyphosphate nanoparticles: impact of particle size molecular weight

    Science.gov (United States)

    Sarwar, Atif; Katas, Haliza; Zin, Noraziah Mohamad

    2014-07-01

    This study revealed not only the antibacterial potential of smaller chitosan-tripolyphosphate nanoparticles (CS-TPP NPs) over larger ones, but also the attempt has been made to demonstrate antibacterial mechanism of action of CS-TPP NPs on the bacterial cell membrane. Several aspects of low-molecular-weight (LMW) and high-molecular-weight (HMW) CS-TPP NPs were evaluated by their interactions with selected Gram-positive and Gram-negative bacteria. The interaction of CS-TPP NPs with synthetic phospholipid membranes was also evaluated using Fourier transform infrared spectroscopy. The permeabilities of the bacterial outer and inner membranes were evaluated by determining the uptake of a fluorescent probe, 1- N-phenylnaphthylamine, and the release of cytoplasmic β-galactosidase. The morphology of the bacteria treated with LMW and HMW CS-TPP NPs was investigated using transmission electron microscopy. Flow cytometric analysis was also performed for the quantification of dead and surviving bacteria. These studies indicated that the antibacterial effects of LMW CS-TPP NPs (196 and 394 nm) were superior to those HMW CS-TPP NPs (598 and 872 nm). These data indicated that the antibacterial activity of CS-TPP NPs was negatively correlated with particle size and molecular weight, and that CS-TPP NPs represent a promising antimicrobial adjunct.

  10. Temperature dependence of viscoelasticity of crystalline cellulose with different molecular weights added to silicone elastomer

    Science.gov (United States)

    Sugino, Naoto; Nakajima, Shinya; Kameda, Takao; Takei, Satoshi; Hanabata, Makoto

    2017-08-01

    Silicone elastomers ( polydimethylsiloxane _ PDMS) are widely used in the field of imprint lithography and microcontactprinting (μCP). When performing microcontactprinting, the mechanical properties of the PCMS as a base material have a great influence on the performance of the device. Cellulose nanofibers having features of high strength, high elasticity and low coefficient of linear expansion have attracted attention in recent years due to their characteristics. Therefore, three types of crystalline cellulose having different molecular weights were added to PDMS to prepare a composite material, and dynamic viscoelasticity was measured using a rheometer. The PDMS with the highest molecular weight crystalline cellulose added exhibited smaller storage modulus than PDMS with other molecular weight added in all temperature ranges. Furthermore, when comparing PDMS to which crystalline cellulose was added and PDMS which is not added, the storage modulus of PDMS to which cellulose was added in the low temperature region was higher than that of PDMS to which it was not added, but it was reversed in the high temperature region It was a result. When used in a low temperature range (less than 150 ° C.), it can be said that cellulose can function as a reinforcing material for PDMS.

  11. Role of Molecular Weight on the Mechanical Device Properties of Organic Polymer Solar Cells

    KAUST Repository

    Bruner, Christopher

    2014-02-11

    For semiconducting polymers, such as regioregular poly(3-hexylthiophene-2, 5-diyl) (rr-P3HT), the molecular weight has been correlated to charge carrier field-effect mobilities, surface morphology, and gelation rates in solution and therefore has important implications for long-Term reliability, manufacturing, and future applications of electronic organic thin films. In this work, we show that the molecular weight rr-P3HT in organic solar cells can also significantly change the internal cohesion of the photoactive layer using micromechanical testing techniques. Cohesive values ranged from ∼0.5 to ∼17 J m -2, following the general trend of greater cohesion with increasing molecular weight. Using nanodynamic mechanical analysis, we attribute the increase in cohesion to increased plasticity which helps dissipate the applied energy. Finally, we correlate photovoltaic efficiency with cohesion to assess the device physics pertinent to optimizing device reliability. This research elucidates the fundamental parameters which affect both the mechanical stability and efficiency of polymer solar cells. © 2014 American Chemical Society.

  12. Prediction models for drug-induced hepatotoxicity by using weighted molecular fingerprints.

    Science.gov (United States)

    Kim, Eunyoung; Nam, Hojung

    2017-05-31

    Drug-induced liver injury (DILI) is a critical issue in drug development because DILI causes failures in clinical trials and the withdrawal of approved drugs from the market. There have been many attempts to predict the risk of DILI based on in vivo and in silico identification of hepatotoxic compounds. In the current study, we propose the in silico prediction model predicting DILI using weighted molecular fingerprints. In this study, we used 881 bits of molecular fingerprint and used as features describing presence or absence of each substructure of compounds. Then, the Bayesian probability of each substructure was calculated and labeled (positive or negative for DILI), and a weighted fingerprint was determined from the ratio of DILI-positive to DILI-negative probability values. Using weighted fingerprint features, the prediction models were trained and evaluated with the Random Forest (RF) and Support Vector Machine (SVM) algorithms. The constructed models yielded accuracies of 73.8% and 72.6%, AUCs of 0.791 and 0.768 in cross-validation. In independent tests, models achieved accuracies of 60.1% and 61.1% for RF and SVM, respectively. The results validated that weighted features helped increase overall performance of prediction models. The constructed models were further applied to the prediction of natural compounds in herbs to identify DILI potential, and 13,996 unique herbal compounds were predicted as DILI-positive with the SVM model. The prediction models with weighted features increased the performance compared to non-weighted models. Moreover, we predicted the DILI potential of herbs with the best performed model, and the prediction results suggest that many herbal compounds could have potential to be DILI. We can thus infer that taking natural products without detailed references about the relevant pathways may be dangerous. Considering the frequency of use of compounds in natural herbs and their increased application in drug development, DILI labeling

  13. Antithrombotic activity of oral administered low molecular weight fucoidan from Laminaria Japonica.

    Science.gov (United States)

    Zhao, Xue; Guo, Fengjun; Hu, Jing; Zhang, Lijuan; Xue, Changhu; Zhang, Zhaohui; Li, Bafang

    2016-08-01

    Fucoidans extracted from brown algae have been documented to have excellent antithrombotic activity when administered by either intravenous or subcutaneous route in animal models. However, it is unknown if the fucoidans also have antithrombotic activity when administered orally, a highly desirable feature of oral antithrombotic agents. In the present study, we compared the oral absorption, bioavailability and antithrombotic activity of two fucoidan fractions from Laminaria japonica with different molecular weight by oral administration in an electricity induced arterial thrombosis model and the underlying molecular mechanisms. After a single dose of oral administration, the fucoidan content in plasma and urine in rats was assessed using the reverse-phased HPLC analysis of 1-phenyl-3-methyl-5-pyrazolone (PMP)-labeled fucose. The fucose content in the low molecular weight (LMW) fucoidan-treated rats increased up to 2-fold and peaked at 15h, indicating that the LMW fucoidan had much better absorption and bioavailability than the MMW fucoidan in vivo. Oral administration of the LMW fucoidan at 400 and 800mg/kg for 30days inhibited the arterial thrombosis formation effectively induced by electrical shock in rats, accompanied by moderate anticoagulation activity, regulation on TXB2 and 6-keto-PGF1α, significant antiplatelet activity and effective fibrinolysis. The LMW fucoidan showed better oral absorption and antithrombotic activity in addition to different antithrombotic mechanisms compared to those of the medium molecular weight (MMW) fucoidan. Thus, the LMW fucoidan has a potential to become an oral antithrombotic agent. Copyright © 2016. Published by Elsevier Ltd.

  14. Effect of PEG molecular weight and PEGylation degree on the physical stability of PEGylated lysozyme.

    Science.gov (United States)

    Morgenstern, Josefine; Baumann, Pascal; Brunner, Carina; Hubbuch, Jürgen

    2017-03-15

    During production, purification, formulation, and storage proteins for pharmaceutical or biotechnological applications face solution conditions that are unfavorable for their stability. Such harmful conditions include extreme pH changes, high ionic strengths or elevated temperatures. The characterization of the main influencing factors promoting undesired changes of protein conformation and aggregation, as well as the manipulation and selective control of protein stabilities are crucially important to biopharmaceutical research and process development. In this context PEGylation, i.e. the covalent attachment of polyethylene glycol (PEG) to proteins, represents a valuable strategy to improve the physico-chemical properties of proteins. In this work, the influence of PEG molecular weight and PEGylation degree on the physical stability of PEGylated lysozyme is investigated. Specifically, conformational and colloidal properties were studied by means of high-throughput melting point determination and automated generation of protein phase diagrams, respectively. Lysozyme from chicken egg-white as a model protein was randomly conjugated to 2kDa, 5kDa and 10kDa mPEG-aldehyde and resulting PEGamer species were purified by chromatographic separation. Besides protein stability assessment, residual enzyme activities were evaluated employing a Micrococcus lysodeikticus based activity assay. PEG molecules with lower molecular weights and lower PEGylation degrees resulted in higher residual activities. Changes in enzyme activities upon PEGylation have shown to result from a combination of steric hindrance and molecular flexibility. In contrast, higher PEG molecular weights and PEGylation degrees enhanced conformational and colloidal stability. By PEGylating lysozyme an increase of the protein solubility by more than 11-fold was achieved. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Autoadhesion of High-Molecular-Weight Monodisperse Glassy Polystyrene at unexpected low temperatures

    DEFF Research Database (Denmark)

    Boiko, Yuri M.; Lyngaae-Jørgensen, Jørgen

    2004-01-01

    -bulk corresponding to a second-order phase transition temperature). To our knowledge, this is the first observation of such nature, which gives further evidence of the lowering of the T-g at polymeric surfaces and the persistence of this effect at early stages of healing of polymer-polymer interfaces.......Healing of symmetric interfaces of amorphous anionically polymerized high- and ultra-high-molecular weight (HMW and UHMW, respectively) polystyrene (PS) in a range of the weight-average molecular weight M-w from 102.5 (M-w/M-n = 1.05) to 1110 kg/ mol (M-w/M-n = 1.15) was followed at a constant...... healing temperature, T-h, well below the glass transition temperature of the polymer bulk [Tg-bulk = 105 - 106degreesC as measured by differential scanning calorimeter (DSC)]. The bonded interfaces were shear fractured in tension on an Instron tester at ambient temperature. Autoadhesion at symmetric HMW...

  16. Effect of gamma irradiation on the friction and wear of ultrahigh molecular weight polyethylene

    Science.gov (United States)

    Jones, W. R.; Hady, W. F.; Crugnola, A.

    1981-01-01

    The effect of sterilization gamma irradiation on the friction and wear properties of ultrahigh molecular weight polyethylene (UHMWPE) sliding against stainless steel 316L in dry air at 23 C is investigated, the results to be used in the development of artificial joints which are to surgically replace diseased human joints. A pin-on-disk sliding friction apparatus is used, a constant sliding speed in the range 0.061-0.27 m/s is maintained, a normal load of 1 kgf is applied with dead weight, and the irradiation dose levels are: 0, 2.5, and 5.0 Mrad. Wear and friction data and conditions for each of the ten tests are summarized, and include: (1) wear volume as a function of the sliding distance for the irradiation levels, (2) incremental wear rate, and (3) coefficient of friction as a function of the sliding distance. It is shown that (1) the friction and wear properties of UHMWPE are not significantly changed by the irradiation doses of 2.5 and 5.0 Mrad, (2) the irradiation increases the amount of insoluble gel as well as the amount of low molecular weight material, and (3) after run-in the wear rate is either steady or gradually decreases as a function of the sliding distance.

  17. Ballistic behaviour of ultra-high molecular weight polyethylene: effect of gamma radiation

    International Nuclear Information System (INIS)

    Alves, Andreia L.S.; Nascimento, Lucio F.C.; Miguez Suarez, Joao Carlos

    2004-01-01

    The fiber reinforced polymer matrix composites (PMCs) are considered excellent engineering materials. In structural applications, when a high strength-to-weight ratio is fundamental for the design, PMCs are successfully replacing many conventional materials. Since World War II textile materials have been used as ballistic armor. Materials manufactured with ultrahigh molecular weight polyethylene (UHMWPE) fibers are used in the production of armor materials, for personnel protection and armored vehicles. As these have been developed and commercialized more recently, there is not enough information about the action of the ionizing radiation in the ballistic performance of this armor material. In the present work the ballistic behavior of composite plates manufactured with ultrahigh molecular weight polyethylene (UHMWPE) fibers were evaluated after exposure to gamma radiation. The ballistic tests results were related to the macromolecular modifications induced by the environmental degradation through mechanical (hardness, impact and flexure) and physicochemical (infrared spectroscopy, differential scanning calorimetry and thermal gravimetric analysis) tests. Our results indicate that gamma irradiation induces modifications in the UHMWPE macromolecular chains, altering the mechanical properties of the composite and decreasing, for higher radiation doses, its ballistic performance. These results are presented and discussed. (author)

  18. Monte Carlo study of molecular weight distribution changes induced by degradation of ion beam irradiated polymers

    Energy Technology Data Exchange (ETDEWEB)

    Chappa, V.C., E-mail: chappa@tandar.cnea.gov.a [Gerencia de Investigacion y Aplicaciones, TANDAR-CNEA, Av. Gral. Paz 1499, B1650KNA San Martin, Buenos Aires (Argentina); CONICET (Argentina); Pastorino, C.; Grosso, M.F. dwel; Arbeitman, C.R. [Gerencia de Investigacion y Aplicaciones, TANDAR-CNEA, Av. Gral. Paz 1499, B1650KNA San Martin, Buenos Aires (Argentina); CONICET (Argentina); Mueller, M. [Institut fuer Theoretische Physik, Georg-August-Universitaet, Goettingen (Germany); Garci' a Bermudez, G. [Gerencia de Investigacion y Aplicaciones, TANDAR-CNEA, Av. Gral. Paz 1499, B1650KNA San Martin, Buenos Aires (Argentina); CONICET (Argentina); Escuela de Ciencia y Tecnologi' a, UNSAM (Argentina)

    2010-10-01

    In this work we study a polymeric material that degrades upon irradiation due to the energy inhomogeneously deposited by heavy ion beams. Ion beam irradiation of polymers generates rather different effects than those induced by 'classical' low ionizing particles such as electrons or gamma rays. This is due to the high electronic stopping power and the inhomogeneous distribution of deposited energy. This energy is transferred to the material within a small volume along the ion path forming the so called 'nuclear track' or 'latent track'. The track size primarily depends on the ion velocity, and it is determined by the secondary electrons (delta rays) generated along the ion trajectory. By means of Monte Carlo simulations we first obtained equilibrated polymer configurations using a coarse-grained model, and then investigated the spatially inhomogeneous chain scission process due to the passage of the ions. The number average molecular weight, weight average molecular weight and the polydispersity were calculated as a function of track radius, scission probability within the ion track and irradiation fluence. Finally we compared our results with a numerical implementation of a model for random homogeneous degradation.

  19. Chitosans of different molecular weight enhance potato (Solanum tuberosum L. yield in a field trial

    Directory of Open Access Journals (Sweden)

    Alejandro B. Falcón-Rodríguez

    2017-04-01

    Full Text Available Physico-chemical features of chitosan affect its biological activity on plants. In this work, the influence of chitosan molecular mass in potato (Solanum tuberosum L. yields was investigated. By using chitosan polymers of high (CH-1 and low (CH-2 molecular weight and a hydrolysed chitosan derivative (CHH, two experiments were performed under field conditions to determine the effect of these polymers on yields of two potato varieties, ‘Call White’ and ‘Santana’. For this purpose, the foliar spray of low doses of the derivatives at three cultivation moments was performed and several yield variables were determined at crop harvest. All three chitosan compounds increased the performance variables determined respect to the control, depending on the variable, the dose employed and the mass of the derivative evaluated. In most variables determined, the two lowest doses (200 and 325 mg/ha provoked the highest increments above control. Chitosans also affected distribution of mass per tuber size, particularly; in ‘Santana’ variety the two lowest doses enhanced the commercial tuber sizes. Among the polymers, CH-1 caused the greatest increases in performance, while, compared to the polymer, CHH provoked higher yields. In conclusion, foliar application at low doses of high molecular weight and hydrolysed chitosan enhanced potato yield between 15-30%.

  20. Direct Measurement of Crazing Mechanics in Polystyrene Thin Films: Molecular Weight Effects

    Science.gov (United States)

    Shimomura, Shinichiro; Bay, Reed; Ilton, Mark; Crosby, Alfred

    Mechanical properties of polymer thin films are critical to various applications such as protective coatings, electronic devices, and separation membranes. Although methods for measuring the structure and some physical properties, such as Tg, of polymer thin films have been well established, measuring mechanical properties of thin films has not been fully developed and has been largely limited to extremely small strains and complex stress distributions. To overcome these limitations, we have recently introduced a direct measurement technique for quantifying the complete uniaxial stress-strain relationship for polymer thin films. Here, we use `dog-bone' shaped thin films of polystyrene (PS) to quantify the change in mechanical response as a function of molecular weight. We observe a nonlinear stress-strain relationship, resembling ideal plastic-like behavior, associated with the onset of crazing. We will discuss how the onset stress and critical strain to failure changes as a function of molecular weight. These changes, and the alignment of craze fibrils, are discussed in the context of how entanglement density is altered for confined thin films. These results provide new insight into fundamental molecular physics for polymer thin films.

  1. Correlation between human maternal-fetal placental transfer and molecular weight of PCB and dioxin congeners/isomers.

    Science.gov (United States)

    Mori, Chisato; Nakamura, Noriko; Todaka, Emiko; Fujisaki, Takeyoshi; Matsuno, Yoshiharu; Nakaoka, Hiroko; Hanazato, Masamichi

    2014-11-01

    Establishing methods for the assessment of fetal exposure to chemicals is important for the prevention or prediction of the child's future disease risk. In the present study, we aimed to determine the influence of molecular weight on the likelihood of chemical transfer from mother to fetus via the placenta. The correlation between molecular weight and placental transfer rates of congeners/isomers of polychlorinated biphenyls (PCBs) and dioxins was examined. Twenty-nine sample sets of maternal blood, umbilical cord, and umbilical cord blood were used to measure PCB concentration, and 41 sample sets were used to analyze dioxins. Placental transfer rates were calculated using the concentrations of PCBs, dioxins, and their congeners/isomers within these sample sets. Transfer rate correlated negatively with molecular weight for PCB congeners, normalized using wet and lipid weights. The transfer rates of PCB or dioxin congeners differed from those of total PCBs or dioxins. The transfer rate for dioxin congeners did not always correlate significantly with molecular weight, perhaps because of the small sample size or other factors. Further improvement of the analytical methods for dioxin congeners is required. The findings of the present study suggested that PCBs, dioxins, or their congeners with lower molecular weights are more likely to be transferred from mother to fetus via the placenta. Consideration of chemical molecular weight and transfer rate could therefore contribute to the assessment of fetal exposure. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. ESIprot: a universal tool for charge state determination and molecular weight calculation of proteins from electrospray ionization mass spectrometry data.

    Science.gov (United States)

    Winkler, Robert

    2010-02-01

    Electrospray ionization (ESI) ion trap mass spectrometers with relatively low resolution are frequently used for the analysis of natural products and peptides. Although ESI spectra of multiply charged protein molecules also can be measured on this type of devices, only average spectra are produced for the majority of naturally occurring proteins. Evaluating such ESI protein spectra would provide valuable information about the native state of investigated proteins. However, no suitable and freely available software could be found which allows the charge state determination and molecular weight calculation of single proteins from average ESI-MS data. Therefore, an algorithm based on standard deviation optimization (scatter minimization) was implemented for the analysis of protein ESI-MS data. The resulting software ESIprot was tested with ESI-MS data of six intact reference proteins between 12.4 and 66.7 kDa. In all cases, the correct charge states could be determined. The obtained absolute mass errors were in a range between -0.2 and 1.2 Da, the relative errors below 30 ppm. The possible mass accuracy allows for valid conclusions about the actual condition of proteins. Moreover, the ESIprot algorithm demonstrates an extraordinary robustness and allows spectral interpretation from as little as two peaks, given sufficient quality of the provided m/z data, without the necessity for peak intensity data. ESIprot is independent from the raw data format and the computer platform, making it a versatile tool for mass spectrometrists. The program code was released under the open-source GPLv3 license to support future developments of mass spectrometry software. Copyright 2010 John Wiley & Sons, Ltd.

  3. Antarctic snow: metals bound to high molecular weight dissolved organic matter.

    Science.gov (United States)

    Calace, Nicoletta; Nardi, Elisa; Pietroletti, Marco; Bartolucci, Eugenia; Pietrantonio, Massimiliana; Cremisini, Carlo

    2017-05-01

    In this paper we studied some heavy metals (Cu, Zn, Cd, Pb, As, U) probably associated to high molecular weight organic compounds present in the Antarctic snow. Snow-pit samples were collected and analysed for high molecular weight fraction and heavy metals bound to them by means of ultrafiltration treatment. High molecular weight dissolved organic matter (HMW-DOM) recovered by ultrafiltration showed a dissolved organic carbon concentration (HMW-DOC) of about 18-83% of the total dissolved organic carbon measured in Antarctic snow. The characterisation of HMW-DOM fraction evidenced an ageing of organic compounds going from surface layers to the deepest ones with a shift from aliphatic compounds and proteins/amino sugars to more high unsaturated character and less nitrogen content. The heavy metals associated to HMW-DOM fraction follows the order: Zn > Cu > Pb > Cd ∼ As ∼ U. The percentage fraction of metals bound to HMW-DOM respect to total metal content follows the order: Cu > Pb > Zn, Cd in agreement with humic substance binding ability (Irwing-William series). Going down to depth of trench, all metals except arsenic, showed a high concentration peak corresponding to 2.0-2.5 m layer. This result was attributed to particular structural characteristic of organic matter able to form different type of complexes (1:1, 1:2, 1:n) with metals. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Measurement of low molecular weight silicon AMC to protect UV optics in photo-lithography environments

    Science.gov (United States)

    Lobert, Jürgen M.; Miller, Charles M.; Grayfer, Anatoly; Tivin, Anne M.

    2009-03-01

    A new analytical method for semiconductor-specific applications is presented for the accurate measurement of low molecular weight, silicon-containing, organic compounds TMS, HMDSO and D3. Low molecular weight / low boiling point silicon-containing compounds are not captured for extended periods of time by traditional chemical filters but have the same potential to degrade exposure tool optical surfaces as their high molecular weight counterparts. Likewise, we show that capturing these compounds on sample traps that are commonly used for organic AMC analysis does not work for various reasons. Using the analytical method described here, TMS, HMDSO and D3 can be measured artifact-free, with at least a 50:1 peak-to-noise ratio at the method detection limit, determined through the Hubaux-Vos method and satisfying a conservative 99% statistical confidence. Method detection limits for the compounds are 1-6 ppt in air. We present calibration curve, capacity, capture efficiency, break-through and repeatability data to demonstrate robustness of method. Seventy-one real-world samples from 26 projects taken in several fab environments show that TMS is found in concentrations 100 times higher than those of HMDSO and D3. All compounds are found in all environments in concentrations ranging from zero to 12 ppm, but most concentrations were below 50 ppb. All compounds are noticeably higher in litho-bays than in sub-fabs and we found all three compounds inside of two exposure tools, suggesting cleanroom and/or tool-internal contamination sources.

  5. Nanostructures on spin-coated polymer films controlled by solvent composition and polymer molecular weight

    Energy Technology Data Exchange (ETDEWEB)

    Dario, Aline F.; Macia, Henrique B.; Petri, Denise F.S., E-mail: dfsp@iq.usp.br

    2012-12-01

    In this study we systematically investigated how the solvent composition used for polymer dissolution affects the porous structures of spin-coated polymers films. Cellulose acetate butyrate (CAB) and poly(methyl methacrylate) with low (PMMA-L) and high (PMMA-H) molecular weights were dissolved in mixtures of acetone (AC) and ethyl acetate (EA) at constant polymer concentration of 10 g/L The films were spin-coated at a relative air humidity of 55 {+-} 5%, their thickness and index of refraction were determined by means of ellipsometry and their morphology was analyzed by atomic force microscopy. The dimensions and frequency of nanocavities on polymer films increased with the acetone content ({phi}{sub AC}) in the solvent mixture and decreased with increasing polymer molecular weight. Consequently, as the void content increased in the films, their apparent thicknesses increased and their indices of refraction decreased, creating low-cost anti-reflection surface. The void depth was larger for PMMA-L than for CAB. This effect was attributed to different activities of EA and AC in CAB or PMMA-L solution, the larger mobility of chains and the lower polarity of PMMA-L in comparison to CAB. - Highlights: Black-Right-Pointing-Pointer Nanostructures in spin-coated polymer films depend on the solvent vapor pressure. Black-Right-Pointing-Pointer Anti-reflection polymer films are produced at high solvent vapor pressure. Black-Right-Pointing-Pointer Only shallow cavities are obtained in films of polymers with high molecular weight.

  6. High molecular weight hyaluronan mediates the cancer resistance of the naked mole-rat

    Science.gov (United States)

    Tian, Xiao; Azpurua, Jorge; Hine, Christopher; Vaidya, Amita; Myakishev-Rempel, Max; Ablaeva, Julia; Mao, Zhiyong; Nevo, Eviatar; Gorbunova, Vera; Seluanov, Andrei

    2013-01-01

    The naked mole-rat displays exceptional longevity, with a maximum lifespan exceeding 30 years1–3. This is the longest reported lifespan for a rodent species and is especially striking considering the small body mass of the naked mole-rat. In comparison, a similarly sized house mouse has a maximum lifespan of 4 years4,5. In addition to their longevity, naked mole-rats show an unusual resistance to cancer. Multi-year observations of large naked mole-rat colonies did not detect a single incidence of cancer2,6. Here we identify a mechanism responsible for the naked mole-rat’s cancer resistance. We found that naked mole-rat fibroblasts secrete extremely high molecular weight hyaluronan (HA), which is over five times larger than human or mouse HA. This high molecular weight HA accumulates abundantly in naked mole rat tissues due to the decreased activity of HA-degrading enzymes and a unique sequence of hyaluronan synthase 2 (HAS2). Furthermore, the naked mole-rat cells are more sensitive to HA signaling, as the naked mole rat cells have a higher affinity to HA than the mouse or human cells. Perturbation of the signaling pathways sufficient for malignant transformation of mouse fibroblasts fails to transform naked mole-rat cells. However, once high molecular weight HA is removed by either knocking down HAS2 or overexpressing the HA-degrading enzyme, Hyal2, naked mole-rat cells become susceptible to malignant transformation and readily form tumors in mice. We speculate that naked mole-rats have evolved a higher concentration of HA in the skin to provide skin elasticity needed for life in underground tunnels. This trait may have then been co-opted to provide cancer resistance and longevity to this species. PMID:23783513

  7. Effect of molecular weight reduction by gamma irradiation on chitosan film properties

    International Nuclear Information System (INIS)

    García, Mario A.; Pérez, Liliam; Paz, Nilia de la; González, Juan; Rapado, Manuel; Casariego, Alicia

    2015-01-01

    The present work aimed the influence of molecular weight (MW) reduction by irradiation with 60 Co and polymer concentration on some physical properties of chitosan films. Irradiation of chitosan with a MW of 275.221 kDa and 74.74% of deacetylation degree was performed using a 60 Co source to provide doses of 5, 10, 20 and 50 kGy to obtain chitosans with molecular weights of 247.847, 221.563, 126.469 and 77.063 kDa, respectively. Films were prepared via the solution casting method. Film-forming solutions (FFS) of chitosan irradiated or not, were prepared at 1.5 and 2% (w/v) in a solution of lactic acid at 1% (v/v) and 0.1% (v/v) of Tween 80. The FFS were poured into glass plates of 400 cm 2 and dried at 60 °C during 10 h without airflow. The decrease of MW and increase of chitosan concentration increased the tensil strength and water vapor permeability while decreased the elongation at break of the films. The chitosan MW did not significantly influence (p > 0.05) the water solubility of films within a same polymer concentration. There was a decrease in the films' brightness with the increase of concentration and a decrease of the MW of irradiated chitosan, while the b* values of films increased and there was an increasing tendency of their apparent opacity. - Highlights: • MW reduction by 60 Co irradiation increased the tensil strength of chitosan films. • MW reduction increased the water vapor permeability of chitosan films. • MW did not affect the films' water solubility within a same chitosan concentration. • Films' brightness decreased with the chitosan molecular weight reduction

  8. ADME-Tox profiling of some low molecular weight water soluble chitosan derivatives

    Directory of Open Access Journals (Sweden)

    Adriana Isvoran

    2017-09-01

    Full Text Available Within this study we use a few computational tools for predicting absorption, distribution, metabolism, excretion and toxicity (ADME-Tox, pharmacokinetics profiles, toxic/adverse effects, carcinogenicity, cardiotoxicity and endocrine disruption of some of low molecular weight water soluble derivatives of chitosan that are used in wound healing. Investigated compounds do not possess drug-like properties, their pharmacokinetics profiles reveal poor gastrointestinal absorption and low skin penetration. Chitosan derivatives cannot pass the blood-brain barrier and they are not able to inhibit the enzymes of the cytochrome P450 that are involved in the metabolism of xenobiotics. They do not reflect carcinogenicity and cardiotoxicity and reveal only a low probability to be endocrine disruptors. The main side effects in humans of the investigated compounds are: weight loss, acidosis, gastrointestinal toxicity, respiratory failure. This information is especially important for professional exposure and accidental contamination with these compounds.

  9. Molecular Weight Effects on the Glass Transition and Confinement Behavior of Polymer Thin Films.

    Science.gov (United States)

    Xia, Wenjie; Hsu, David D; Keten, Sinan

    2015-08-01

    Nanoscale polymer thin films exhibit strong confinement effects on Tg arising from free surfaces. However, the coupled influence of molecular weight (MW) and surface effects on Tg is not well understood for low MW film systems below the entanglement length. Utilizing atomistically informed coarse-grained molecular dynamics simulations for poly(methyl methacrylate) (PMMA), it is demonstrated that the decrease in free-standing film Tg with respect to bulk is more significant for low MW compared to high MW systems. Investigation of the local interfacial properties reveals that the increase in the local free volume near the free surface is greater for low MW, explaining the MW dependence of Tg -confinement behaviors. These findings corroborate recent experiments on low MW films, and highlight the relationship between nanoconfinement phenomena and local free volume effects arising from free surfaces. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Preparation of high molecular weight gDNA and bacterial artificial chromosome (BAC) libraries in plants.

    Science.gov (United States)

    Biradar, Siddanagouda S; Nie, Xiaojun; Feng, Kewei; Weining, Song

    2014-01-01

    Bacterial artificial chromosome (BAC) libraries are extremely valuable large-insert DNA libraries for physical mapping, positional cloning, comparative genomic analysis, complete genome sequencing, and evolutionary studies. Due to their stability and relative simplicity BAC libraries are most preferred over other approaches for cloning large genomic DNA fragments for large-insert libraries. Isolation of intact high molecular weight (HMW) DNA is a critical step underlying the success of large-insert genomic DNA library construction. It requires the isolation of purified nuclei, embedding them into LMP agarose plugs, restriction digestion of the plugs, and quite often size selection using PFGE and electro-elution of insert DNA. The construction of BAC libraries is complex and challenging for most molecular laboratories. To facilitate the construction of BAC libraries, we present a step-by-step protocol for isolation of HMW DNA and construction of plant BAC libraries.

  11. Detection of high molecular weight proteins by MALDI imaging mass spectrometry.

    Science.gov (United States)

    Mainini, Veronica; Bovo, Giorgio; Chinello, Clizia; Gianazza, Erica; Grasso, Marco; Cattoretti, Giorgio; Magni, Fulvio

    2013-06-01

    MALDI imaging mass spectrometry (IMS) is a unique technology to explore the spatial distribution of biomolecules directly on tissues. It allows the in situ investigation of a large number of small proteins and peptides. Detection of high molecular weight proteins through MALDI IMS still represents an important challenge, as it would allow the direct investigation of the distribution of more proteins involved in biological processes, such as cytokines, enzymes, neuropeptide precursors and receptors. In this work we compare the traditional method performed with sinapinic acid with a comparable protocol using ferulic acid as the matrix. Data show a remarkable increase of signal acquisition in the mass range of 20k to 150k Th. Moreover, we report molecular images of biomolecules above 70k Th, demonstrating the possibility of expanding the application of this technology both in clinical investigations and basic science.

  12. Effect of soil sieving on respiration induced by low-molecular-weight substrates

    Science.gov (United States)

    Datta, Rahul; Vranová, Valerie; Pavelka, Marian; Rejšek, Klement; Formánek, Pavel

    2014-03-01

    The mesh size of sieves has a significant impact upon soil disturbance, affecting pore structure, fungal hyphae, proportion of fungi to bacteria, and organic matter fractions. The effects are dependent upon soil type and plant coverage. Sieving through a 2 mm mesh increases mineralization of exogenously supplied carbohydrates and phenolics compared to a 5 mm mesh and the effect is significant (pferulic and pthalic acid metabolism, whereas maltose mineralization is less affected. Sieving through a 5 mm mesh size is suggested for all type of experiments where enhanced mineralization of low-molecular-weight organic compounds needs to be minimalized.

  13. Broadening of molecular weight distribution of polymers synthesized by metallocene-based dual-site catalysts

    International Nuclear Information System (INIS)

    Santos, Joao H.Z. dos; Fisch, Adriano G.; Cardozo, Nilo S.M.; Secchi, Argimiro R.

    2008-01-01

    The main topics related to the use of dual-site catalysts in the production of polymers with broad molecular weight distribution are reviewed. The polymerization using dual-site catalysts is more economical and allows to produce a higher quality product than other processes, such as polymer blend and multistage reactors. However, the formulation of these catalysts is quite complicated since the same catalyst must produce distinct polymer grades. In addition, the release of patents concerning the combination of metallocenes and new technologies for polymerization shows that polymerization processes using dual-site catalysts are of current industrial interest. (author)

  14. Separation and analysis of low molecular weight plasticizers in poly(vinyl chloride) tubes

    DEFF Research Database (Denmark)

    Wang, Qian; Storm, Birgit Kjærside

    2005-01-01

    ) and thermogravimetric analysis (TGA), as well as by studying the extracted low molecular weight plasticizers by gas chromatography/mass spectroscopy (GC/MS) and GC. It was found that the simple room temperature extraction in chloroform showed the best separation of plasticizers from the PVC matrix. Close results...... on extracted diisooctyl phthalate (DOP) concentration were obtained from different methods. Analysis on one kind of the used tubes showed that 64-67% of DOP migrated to the patient, but bis(2-ethylhexyl) adipate (DOA) was 70-100% retained....

  15. Venous thromboembolism in pregnancy: prophylaxis and treatment with low molecular weight heparin

    DEFF Research Database (Denmark)

    Andersen, Anita Sylvest; Berthelsen, Jørgen G; Bergholt, Thomas

    2010-01-01

    OBJECTIVE: To evaluate the safety of individually dosed low molecular weight heparin (LMWH) for prophylaxis and treatment of thromboembolic complications in pregnancy. DESIGN: Cohort study with a chronologic register-based control group. SETTING: Department of Obstetrics and Gynecology, Hillerød...... side effects of treatment and no osteoporotic fractures or episodes of heparin-induced thrombocytopenia. The 166 pregnancies resulted in 159 live infants. There was a significantly higher risk of preterm delivery (13% vs. 6%) and intrauterine growth restriction (4.4% vs. 3.5%). Delivery by cesarean...

  16. Study on different molecular weights of chitosan as an immobilization matrix for a glucose biosensor.

    Science.gov (United States)

    Ang, Lee Fung; Por, Lip Yee; Yam, Mun Fei

    2013-01-01

    Two chitosan samples (medium molecular weight (MMCHI) and low molecular weight (LMCHI)) were investigated as an enzyme immobilization matrix for the fabrication of a glucose biosensor. Chitosan membranes prepared from acetic acid were flexible, transparent, smooth and quick-drying. The FTIR spectra showed the existence of intermolecular interactions between chitosan and glucose oxidase (GOD). Higher catalytic activities were observed on for GOD-MMCHI than GOD-LMCHI and for those crosslinked with glutaraldehyde than using the adsorption technique. Enzyme loading greater than 0.6 mg decreased the activity. Under optimum conditions (pH 6.0, 35°C and applied potential of 0.6 V) response times of 85 s and 65 s were observed for medium molecular weight chitosan glucose biosensor (GOD-MMCHI/PT) and low molecular weight chitosan glucose biosensor (GOD-LMCHI/PT), respectively. The apparent Michaelis-Menten constant ([Formula: see text]) was found to be 12.737 mM for GOD-MMCHI/PT and 17.692 mM for GOD-LMCHI/PT. This indicated that GOD-MMCHI/PT had greater affinity for the enzyme. Moreover, GOD-MMCHI/PT showed higher sensitivity (52.3666 nA/mM glucose) when compared with GOD-LMCHI/PT (9.8579 nA/mM glucose) at S/N>3. Better repeatability and reproducibility were achieved with GOD-MMCHI/PT than GOD-LMCHI/PT regarding glucose measurement. GOD-MMCHI/PT was found to give the highest enzymatic activity among the electrodes under investigation. The extent of interference encountered by GOD-MMCHI/PT and GOD-LMCHI/PT was not significantly different. Although the Nafion coated biosensor significantly reduced the signal due to the interferents under study, it also significantly reduced the response to glucose. The performance of the biosensors in the determination of glucose in rat serum was evaluated. Comparatively better accuracy and recovery results were obtained for GOD-MMCHI/PT. Hence, GOD-MMCHI/PT showed a better performance when compared with GOD-LMCHI/PT. In conclusion

  17. Calcium binding to low molecular weight compounds and health promoting products

    DEFF Research Database (Denmark)

    Vavrusova, Martina

    food. Therefore, an understanding of the basic chemistry of calcium binding to low molecular weight compounds can contribute to a general knowledge about calcium bioavailability and also to product improvement. Calcium precipitation with palmitate was described by a first-order reaction for conditions...... only slowly precipitated after a lag phase. On the other hand, the slow dissolution of calcium D-gluconate by sodium L-lactate in aqueous solution with the reverse lactate/gluconate ratio did not result in a similar solution since fast precipitation prevented formation of a homogenous solution....

  18. Preparation and tribological properties of chitosan/hydroxyapatite composite coatings applied on ultra high molecular weight polyethylene substrate

    OpenAIRE

    Navarro, Carolina H.; Moreno, Karla J.; Arizmendi-Morquecho, Ana; Chávez-Valdez, Alejandra; Garcia-Miranda, Santos

    2013-01-01

    We prepared a chitosan/hydroxyapatite composite as coating on ultra–high-molecular-weight polyethylene substrates. The hydroxyapatite was prepared by a precipitation method obtaining particles with nanometer sizes with needle and spherical morphologies. The coating was prepared by a mixture of hydroxyapatite and lower molecular weight chitosan. Fourier transformed infrared spectroscopy technique was used to study the hydroxyapatite synthesis and composite coating. The chitosan/hydroxyapatite ...

  19. High Molecular Weight Typing with MALDI-TOF MS - A Novel Method for Rapid Typing of Clostridium difficile

    OpenAIRE

    Rizzardi, Kristina; ?kerlund, Thomas

    2015-01-01

    Clostridium difficile strains were typed by a newly developed MALDI-TOF method, high molecular weight typing, and compared to PCR ribotyping. Among 500 isolates representing 59 PCR ribotypes a total of 35 high molecular weight types could be resolved. Although less discriminatory than PCR ribotyping, the method is extremely fast and simple, and supports for cost-effective screening of isolates during outbreak situations.

  20. Quantification of low molecular weight compounds by MALDI imaging mass spectrometry - A tutorial review.

    Science.gov (United States)

    Rzagalinski, Ignacy; Volmer, Dietrich A

    2017-07-01

    Matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry imaging (MSI) permits label-free in situ analysis of chemical compounds directly from the surface of two-dimensional biological tissue slices. It links qualitative molecular information of compounds to their spatial coordinates and distribution within the investigated tissue. MALDI-MSI can also provide the quantitative amounts of target compounds in the tissue, if proper calibration techniques are performed. Obviously, as the target molecules are embedded within the biological tissue environment and analysis must be performed at their precise locations, there is no possibility for extensive sample clean-up routines or chromatographic separations as usually performed with homogenized biological materials; ion suppression phenomena therefore become a critical side effect of MALDI-MSI. Absolute quantification by MALDI-MSI should provide an accurate value of the concentration/amount of the compound of interest in relatively small, well-defined region of interest of the examined tissue, ideally in a single pixel. This goal is extremely challenging and will not only depend on the technical possibilities and limitations of the MSI instrument hardware, but equally on the chosen calibration/standardization strategy. These strategies are the main focus of this article and are discussed and contrasted in detail in this tutorial review. This article is part of a Special Issue entitled: MALDI Imaging, edited by Dr. Corinna Henkel and Prof. Peter Hoffmann. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Extraction of High Molecular Weight DNA from Fungal Rust Spores for Long Read Sequencing.

    Science.gov (United States)

    Schwessinger, Benjamin; Rathjen, John P

    2017-01-01

    Wheat rust fungi are complex organisms with a complete life cycle that involves two different host plants and five different spore types. During the asexual infection cycle on wheat, rusts produce massive amounts of dikaryotic urediniospores. These spores are dikaryotic (two nuclei) with each nucleus containing one haploid genome. This dikaryotic state is likely to contribute to their evolutionary success, making them some of the major wheat pathogens globally. Despite this, most published wheat rust genomes are highly fragmented and contain very little haplotype-specific sequence information. Current long-read sequencing technologies hold great promise to provide more contiguous and haplotype-phased genome assemblies. Long reads are able to span repetitive regions and phase structural differences between the haplomes. This increased genome resolution enables the identification of complex loci and the study of genome evolution beyond simple nucleotide polymorphisms. Long-read technologies require pure high molecular weight DNA as an input for sequencing. Here, we describe a DNA extraction protocol for rust spores that yields pure double-stranded DNA molecules with molecular weight of >50 kilo-base pairs (kbp). The isolated DNA is of sufficient purity for PacBio long-read sequencing, but may require additional purification for other sequencing technologies such as Nanopore and 10× Genomics.

  2. Equal channel angular extrusion of ultra-high molecular weight polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Reinitz, Steven D., E-mail: Steven.D.Reinitz.TH@Dartmouth.edu; Engler, Alexander J.; Carlson, Evan M.; Van Citters, Douglas W.

    2016-10-01

    Ultra-high molecular weight polyethylene (UHMWPE), a common bearing surface in total joint arthroplasty, is subject to material property tradeoffs associated with conventional processing techniques. For orthopaedic applications, radiation-induced cross-linking is used to enhance the wear resistance of the material, but cross-linking also restricts relative chain movement in the amorphous regions and hence decreases toughness. Equal Channel Angular Extrusion (ECAE) is proposed as a novel mechanism by which entanglements can be introduced to the polymer bulk during consolidation, with the aim of imparting the same tribological benefits of conventional processing without complete inhibition of chain motion. ECAE processing at temperatures near the crystalline melt for UHMWPE produces (1) increased entanglements compared to control materials; (2) increasing entanglements with increasing temperature; and (3) mechanical properties between values for untreated polyethylene and for cross-linked polyethylene. These results support additional research in ECAE-processed UHMWPE for joint arthroplasty applications. - Highlights: • A new processing method for ultra-high molecular weight polyethylene is introduced. • The process produces a highly entangled polyethylene material. • Entanglements are hypothesized to enhance the wear resistance of polyethylene. • This process eliminates the trade-off between mechanical and wear properties.

  3. Low-molecular-weight hydroxyacids in marine atmospheric aerosol: evidence of a marine microbial origin

    Science.gov (United States)

    Miyazaki, Y.; Sawano, M.; Kawamura, K.

    2014-08-01

    Lactic acid (LA) and glycolic acid (GA), which are low-molecular-weight hydroxyacids, were identified in the particle and gas phases within the marine atmospheric boundary layer over the western subarctic North Pacific. A major portion of LA (81%) and GA (57%) was present in the particulate phase, which is consistent with the presence of a hydroxyl group in these molecules leading to the low volatility of the compounds. The average concentration (±SD) of LA in more biologically influenced marine aerosols (33 ± 58 ng m-3) was substantially higher than that in less biologically influenced aerosols (11 ± 12 ng m-3). Over the oceanic region of phytoplankton blooms, the concentration of aerosol LA was comparable to that of oxalic acid, which was the most abundant diacid during the study period. A positive correlation was found between the LA concentrations in more biologically influenced aerosols and chlorophyll a in seawater (r2 = 0.56), suggesting an important production of aerosol LA possibly associated with microbial (e.g., lactobacillus) activity in seawater and/or aerosols. Our finding provides a new insight into the poorly quantified microbial sources of marine organic aerosols (OAs) because such low-molecular-weight hydroxyacids are key intermediates for OA formation.

  4. Molecular Weight and Structural Properties of Biodegradable PLA Synthesized with Different Catalysts by Direct Melt Polycondensation

    Directory of Open Access Journals (Sweden)

    Hyung Woo Lee

    2015-09-01

    Full Text Available Production of biodegradable polylactic acid (PLA from biomassbased lactic acid is widely studied for substituting petro-based plastics or polymers. This study investigated PLA production from commercial lactic acid in a batch reactor by applying a direct melt polycondensation method with two kinds of catalyst, γ-aluminium(III oxide (γ-Al2O3 or zinc oxide (ZnO, in reduced pressure. The molecular weight of the synthesized PLA was determined by capillary viscometry and its structural properties were analyzed by functional group analysis using FT-IR. The yields of polymer production with respect to the theoretical conversion were 47% for γ-Al2O3 and 35% for ZnO. However, the PLA from ZnO had a higher molecular weight (150,600 g/mol than that from γ-Al2O3 (81,400 g/mol. The IR spectra of the synthesized PLA from both catalysts using polycondensation show the same behavior of absorption peaks at wave numbers from 4,500 cm-1 to 500 cm-1, whereas the PLA produced by two other polymerization methods – polycondensation and ring opening polymerization –showed a significant difference in % transmittance intensity pattern as well as peak area absorption at a wave number of 3,500 cm-1 as –OH vibration peak and at 1,750 cm-1 as –C=O carbonyl vibrational peak.

  5. Trypanosoma equiperdum Low Molecular Weight Proteins As Candidates for Specific Serological Diagnosis of Dourine

    Directory of Open Access Journals (Sweden)

    Mirella Luciani

    2018-03-01

    Full Text Available The diagnosis of dourine can be difficult because the clinical signs of this disease in horses are similar to those of surra, caused by Trypanosoma evansi. Moreover, T. equiperdum and T. evansi are closely related and, so far, they cannot be distinguished using serological tests. In a previous work, the T. equiperdum protein pattern recognized by antibodies from dourine-infected horses and the humoral immune response kinetics were investigated by immunoblotting assay; a total of 20 sera from naturally and experimentally infected horses and from healthy animals were tested. Immunoblotting analysis showed that antibodies from infected horses specifically bind T. equiperdum low molecular weight proteins (from 16 to 35 kDa, which are not recognized by antibodies from uninfected horses. In this work, we tested other 615 sera (7 from naturally infected horses and 608 sera from healthy horses and donkeys: results confirmed the data obtained previously. In addition, six SDS-PAGE bands with molecular weight ranging from 10 to 37 kDa were analyzed by mass spectrometry, in order to identify immunogenic proteins that could be used as biomarkers for the diagnosis of dourine. A total of 167 proteins were identified. Among them, 37 were found unique for T. equiperdum. Twenty-four of them could represent possible candidate diagnostic antigens for the development of serological tests specific for T. equiperdum.

  6. Role of surfactant molecular weight on morphology and properties of functionalized graphite oxide filled polypropylene nanocomposites

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2014-12-01

    Full Text Available Various surfactants of different molecular weights, including alkylamine, poly(oxypropylene diamine (POP, and maleic anhydride grafted polypropylene (PPgMA oligomers, were used for simultaneous funtionalization and reduction of graphite oxide (fGO. In this study, the effect of molecular weight and compatibility of the surfactants on the morphology and properties of the nanocomposites are reported. Wide-angle X-ray diffraction (WAXD exhibited a definite interlayer thickness for GOA (alkylamine intercalated GO, however, the diffraction peaks were nearly suppressed for fGOs combining ODA with either POP (GOAP or PPgMA (GOAE. The uniform dispersion of the fGO flakes in the polypropylene matrix resulted in the significant increase in both the degradation temperature and the crystallization temperature. A single characteristic melting peak of monoclinic (α crystalline phase was observed from DSC traces, which was consistent with WAXD results. Dynamic mechanical analysis clearly indicated increase in both the storage modulus and the glass transition temperature of the nanocomposites due to the enhanced affinity between fGO and the polypropylene matrix. However, GOAP composite showed lower E' and Tg than GOAE because POP is less compatible with the matrix than PPgMA oligomer. Dielectric analysis also showed significant increase in both dielectric permittivity and dielectric loss at low frequency regimes with GOAE showing maximum dielectric properties. The finely dispersed GOAE and its compatibility with polymer matrix manifested the interfacial polarization, which gave rise to much greater ε' and ε" than other nanocomposites.

  7. Comprehensive Analysis of Low-Molecular-Weight Human Plasma Proteome Using Top-Down Mass Spectrometry.

    Science.gov (United States)

    Cheon, Dong Huey; Nam, Eun Ji; Park, Kyu Hyung; Woo, Se Joon; Lee, Hye Jin; Kim, Hee Cheol; Yang, Eun Gyeong; Lee, Cheolju; Lee, Ji Eun

    2016-01-04

    While human plasma serves as a great source for disease diagnosis, low-molecular-weight (LMW) proteome (biomarkers. Here we employ top-down mass spectrometry to analyze the LMW proteoforms present in four types of human plasma samples pooled from three healthy controls (HCs) without immunoaffinity depletion and with depletion of the top two, six, and seven high-abundance proteins. The LMW proteoforms were first fractionated based on molecular weight using gel-eluted liquid fraction entrapment electrophoresis (GELFrEE). Then, the GELFrEE fractions containing up to 30 kDa were subjected to nanocapillary-LC-MS/MS, and the high-resolution MS and MS/MS data were processed using ProSightPC 3.0. As a result, a total of 442 LMW proteins and cleaved products, including those with post-translational modifications and single amino acid variations, were identified. From additional comparative analysis of plasma samples without immunoaffinity depletion between HCs and colorectal cancer (CRC) patients via top-down approach, tens of LMW proteoforms, including platelet factor 4, were found to show >1.5-fold changes between the plasma samples of HCs and CRC patients, and six of the LMW proteins were verified by Western blot analysis.

  8. Influence of molecular weight on in vitro immunostimulatory properties of instant coffee.

    Science.gov (United States)

    Passos, Cláudia P; Cepeda, Márcio R; Ferreira, Sónia S; Nunes, Fernando M; Evtuguin, Dmitry V; Madureira, Pedro; Vilanova, Manuel; Coimbra, Manuel A

    2014-10-15

    Instant coffee was prepared and fractionated into higher (>100kDa), medium (5-10, 10-30, 30-100kDa) and lower (1-5, composition characteristics of arabinogalactans and galactomannans were recovered in all fractions. Also, amino acid analysis performed after hydrolysis showed similar compositions in all fractions. On the contrary, free chlorogenic acids and caffeine were only detected in the lowest molecular weight fraction (<1kDa). A direct relationship between the melanoidins browning index and the molecular weight was observed. The fractions obtained were incubated in vitro with murine spleen lymphocytes in order to evaluate their possible immunostimulatory abilities. The surface expression of CD69 (early activation marker) on different lymphocyte sub-populations showed that the fraction with 1-5kDa was able to induce activation of B-lymphocytes. This was the only fraction to induce B-lymphocyte activation, since all the other fractions failed, even when higher concentrations were used. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. UV curable lens production using molecular weight controlled PEEK based acrylic oligomer (Ac-PEEK).

    Science.gov (United States)

    İnan, Tulay Y; Yıldız, Emel; Karaca, Birsen; Dogan, Hacer; Vatansever, Alican; Nalbant, Muhammed; Eken, Koray

    2014-08-01

    We produced UV curable lenses with properties blocking short wave UV light. In the UV-curable formulations, we used an oligomer (Ac-PEEK) with another urethan oligomer (Mw = 2000). Radically active, molecular weight controlled Ac-PEEK was obtained by reacting 2-hydroxyl ethyl methacrylate with molecular- weight- controlled and isocyanate terminated PEEK (Mn = 4500). We characterized all synthesized monomer, oligomer and optical materials with UV/Vis spectrophotometer with interferogram, elemental analyser, mass spectrophotometer, proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermal gravimetric analyzer, differential scanning calorimeter, scanning electron microscopy and gas chromatography. Results suggested that newly synthesized oligomer with the structure of PEEK absorbs short wave UV-light. Ageing tests [ISO 11979-5, Ophthalmic implants-intraocular lenses (IOL)-Part 5: Biocompatibility] performed on the IOL materials were successful. High contact angle of the obtained lenses suggests that all lenses were hydrophobic and SEM results revealed that lenses are morphologically homogeneous. Based on all positive properties just mentioned, we safely conclude that the lenses produced in this study are very promising for IOL production.

  10. Capillary electrophoresis of RNA in hydroxyethylcellulose polymer with various molecular weights.

    Science.gov (United States)

    Li, Zhenqing; Liu, Chenchen; Zhang, Dawei; Luo, Shaopeng; Yamaguchi, Yoshinori

    2016-02-01

    Recent research demonstrates that large numbers of long noncoding RNAs (lncRNAs) in mammals exhibit indices of functionality, and thus analysis of longer RNAs is of great significance. In the present work, we investigated the effect of molecular weight on the separation performance of long RNA by capillary electrophoresis (CE). Results demonstrate that (1) low molecular weight of hydroxyethylcellulose (HEC) (90k) favors the separation of short RNA (RNA was improved and the migration time was linearly extended with the increase of polymer concentration. (2) In the longer chain HEC (250k, 720k and 1300k), the resolution for the small RNA fragment (3000 nt) deteriorated. (3) Based on logarithmic plot, there exist two migration regimes for RNA in short chain HEC (90k), three regimes in moderate chain HEC (250k and 720k), and four regimes in the long chain HEC (1300k). Such a systematic investigation of long RNAs may be useful for research on lncRNAs in the length range of 100-10,000 nt. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Analysis of low molecular weight metabolites in tea using mass spectrometry-based analytical methods.

    Science.gov (United States)

    Fraser, Karl; Harrison, Scott J; Lane, Geoff A; Otter, Don E; Hemar, Yacine; Quek, Siew-Young; Rasmussen, Susanne

    2014-01-01

    Tea is the second most consumed beverage in the world after water and there are numerous reported health benefits as a result of consuming tea, such as reducing the risk of cardiovascular disease and many types of cancer. Thus, there is much interest in the chemical composition of teas, for example; defining components responsible for contributing to reported health benefits; defining quality characteristics such as product flavor; and monitoring for pesticide residues to comply with food safety import/export requirements. Covered in this review are some of the latest developments in mass spectrometry-based analytical techniques for measuring and characterizing low molecular weight components of tea, in particular primary and secondary metabolites. The methodology; more specifically the chromatography and detection mechanisms used in both targeted and non-targeted studies, and their main advantages and disadvantages are discussed. Finally, we comment on the latest techniques that are likely to have significant benefit to analysts in the future, not merely in the area of tea research, but in the analytical chemistry of low molecular weight compounds in general.

  12. Molecular weight distribution of Pinus radiata kraft mill wastewater treated by anaerobic digestion.

    Science.gov (United States)

    Vidal, G; Videla, S; Diez, M C

    2001-04-01

    Kraft mill is responsible for massive discharge of highly polluted effluents. The main characteristics of this effluent are high toxicity and low biodegradability due to tannin, lignin and chlorophenol compounds. The composition may vary dramatically depending, for instance, on the utilised feedstock and process. The purpose of this work was to investigate the molecular weight distribution of Pinus radiata kraft pulping wastewater treated by anaerobic digestion by using two types of anaerobic reactors: fixed bed and sludge blanket. Anaerobic sludge blanket (UASB) and anaerobic filter (AF) were operated. In both reactors, the total alkalinity ranged between 1.0 and 1.5 g CaCO3/l, while the organic load rate (OLR) was increasing during operation from 1.2 to 3.3 gCOD/l d. COD and total phenolic compounds (UV215) removal ranged between 30-50% and 13-20%, respectively, while the BOD5 removal ranged 60-90%. However only a partial biodegradation (10-43%) of tannin and lignin was observed. Results from ultrafiltration analyses indicated that the fraction with a molecular weight (MW) 10,000 MW fraction, colour and COD fraction increased by 14% and 5%, respectively, after anaerobic treatment. It can be concluded from this study, that treatment with UASB or AF reactors is not enough, under the conditions tested, for a large COD removal from Pinus radiata wastewater.

  13. Single intra-articular injection of high molecular weight hyaluronic acid for hip osteoarthritis.

    Science.gov (United States)

    Rivera, Fabrizio

    2016-03-01

    Intra-articular (IA) injection of hyaluronic acid (HA) into the hip joint appears to be safe and well tolerated but only a small number of randomized clinical trials in humans has been published. The objective of this prospective study was to evaluate the efficacy and safety of a single IA injection of high-molecular-weight (2800 kDa) HA (Coxarthrum) for hip osteoarthritis. All patients received a single IA administration of 2.5 % sodium hyaluronate (75 mg/3 mL) of high molecular weight. Fluoroscopy requires an iodized contrast medium (iopamidol, 1 ml) which highlights the capsule before administering HA. Patients were evaluated before IA injection (T0), after 3 months, after 6 months and after 1 year from injection. Results were evaluated by the Brief Pain Inventory (BPI II), Harris Hip Score and a visual analog scale of pain (pain VAS). All treated patients were considered for statistical analysis. Two hundred seven patients were included at T0. The mean age was 67 years (range 46-81). Regarding BPI severity score, changes in pain between T0 and the three following visits were statistically highly significant (p injection of Coxarthrum is effective from the third month and that the results are stable or continue to improve up to 1 year. IV.

  14. Planar microdevices enhance transport of large molecular weight molecules across retinal pigment epithelial cells.

    Science.gov (United States)

    Wade, Jennifer S; Desai, Tejal A

    2014-08-01

    Large molecular weight drug delivery to the posterior eye is challenging due to cellular barriers that hinder drug transport. Understanding how to enhance transport across the retinal barrier is important for the design of new drug delivery systems. A novel mechanism to enhance drug transport is the use of geometric properties, which has not been extensively explored in the retina. Planar SU-8/Poly(ethyleneglycol)dimethacrylate microdevices were constructed using photolithography to deliver FITC dextran across an in vitro retinal model. The model consists of retinal pigment epithelial (RPE) cells grown to confluence on transwell inserts, which provides an environment to investigate the influence of geometry on paracellular and transcellular delivery of encapsulated large molecules. Planar microdevices enhanced transport of large molecular weight dextrans across different models of RPE in a size dependent fashion. Increased drug permeation across the RPE was observed with the addition of microdevices as compared to a traditional bolus of FITC dextran. This phenomena was initiated by a non-toxic interaction between the microdevices and the retinal tight junction proteins. Suggesting that increased drug transport occurs via a paracellular pathway. These experiments provide evidence to support the future use of planar unidirectional microdevices for delivery of biologics in ocular applications.

  15. High and Low Molecular Weight Hyaluronic Acid Differentially Regulate Human Fibrocyte Differentiation

    Science.gov (United States)

    Maharjan, Anu S.; Pilling, Darrell; Gomer, Richard H.

    2011-01-01

    Background Following tissue injury, monocytes can enter the tissue and differentiate into fibroblast-like cells called fibrocytes, but little is known about what regulates this differentiation. Extracellular matrix contains high molecular weight hyaluronic acid (HMWHA; ∼2×106 Da). During injury, HMWHA breaks down to low molecular weight hyaluronic acid (LMWHA; ∼0.8–8×105 Da). Methods and Findings In this report, we show that HMWHA potentiates the differentiation of human monocytes into fibrocytes, while LMWHA inhibits fibrocyte differentiation. Digestion of HMWHA with hyaluronidase produces small hyaluronic acid fragments, and these fragments inhibit fibrocyte differentiation. Monocytes internalize HMWHA and LMWHA equally well, suggesting that the opposing effects on fibrocyte differentiation are not due to differential internalization of HMWHA or LMWHA. Adding HMWHA to PBMC does not appear to affect the levels of the hyaluronic acid receptor CD44, whereas adding LMWHA decreases CD44 levels. The addition of anti-CD44 antibodies potentiates fibrocyte differentiation, suggesting that CD44 mediates at least some of the effect of hyaluronic acid on fibrocyte differentiation. The fibrocyte differentiation-inhibiting factor serum amyloid P (SAP) inhibits HMWHA-induced fibrocyte differentiation and potentiates LMWHA-induced inhibition. Conversely, LMWHA inhibits the ability of HMWHA, interleukin-4 (IL-4), or interleukin-13 (IL-13) to promote fibrocyte differentiation. Conclusions We hypothesize that hyaluronic acid signals at least in part through CD44 to regulate fibrocyte differentiation, with a dominance hierarchy of SAP>LMWHA≥HMWHA>IL-4 or IL-13. PMID:22022512

  16. Synthesis and characterization of high molecular weight hydrophobically modified polyacrylamide nanolatexes using novel nonionic polymerizable surfactants

    Directory of Open Access Journals (Sweden)

    A.M. Al-Sabagh

    2013-12-01

    Full Text Available In this article, nine hydrophobically modified polyacrylamides (HM-PAM nanolatexes, were synthesized by copolymerizing the acrylamide monomer and novel polymerizable surfactants (surfmers. The reaction was carried out by inverse microemulsion copolymerization technique. The copolymerization was initiated by redox initiators composed of potassium peroxodisulphate and sodium bisulfite. The emulsion was stabilized using mixed tween 85 and span 80 as nonionic emulsifiers. The prepared HM-PAMs were classified into three groups according to the surfmers used in the copolymerization. The chemical structures of the prepared HM-PAMs were confirmed by FT-IR, 1H NMR and 13C NMR. The thermal properties were estimated with the thermal gravimetric analysis (TGA. The size and morphology of the prepared latexes were investigated by the dynamic light scattering (DLS and the High Resolution Transmission Electron Microscope (HRTEM. Finally, the molecular weights of the prepared copolymers were determined by the GPC and the viscosity average molecular weight method. They were situated between 1.58 × 106 and 0.89 × 106.

  17. A sulfuric-lactic acid process for efficient purification of fungal chitosan with intact molecular weight.

    Science.gov (United States)

    Naghdi, Mitra; Zamani, Akram; Karimi, Keikhosro

    2014-02-01

    The most recent method of fungal chitosan purification, i.e., two steps of dilute sulfuric acid treatment, pretreatment of cell wall at room temperature for phosphate removal and extraction of chitosan from the phosphate free cell wall at high temperature, significantly reduces the chitosan molecular weight. This study was aimed at improvement of this method. In the pretreatment step, to choose the best conditions, cell wall of Rhizopus oryzae, containing 9% phosphate, 10% glucosamine, and 21% N-acetyl glucosamine, was treated with sulfuric, lactic, acetic, nitric, or hydrochloric acid, at room temperature. Sulfuric acid showed the best performance in phosphate removal (90%) and cell wall recovery (89%). To avoid depolymerisation of chitosan, hot sulfuric acid extraction was replaced with lactic acid treatment at room temperature, and a pure fungal chitosan was obtained (0.12 g/g cell wall). Similar pretreatment and extraction processes were conducted on pure shrimp chitosan and resulted in a chitosan recovery of higher than 87% while the reduction of chitosan viscosity was less than 15%. Therefore, the sulfuric-lactic acid method purified the fungal chitosan without significant molecular weight manipulation. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. High Performance Shape Memory Polyurethane Synthesized with High Molecular Weight Polyol as the Soft Segment

    Directory of Open Access Journals (Sweden)

    Manzoor Ahmad

    2012-05-01

    Full Text Available Shape memory polyurethanes (SMPUs are typically synthesized using polyols of low molecular weight (MW~2,000 g/mol as it is believed that the high density of cross-links in these low molecular weight polyols are essential for high mechanical strength and good shape memory effect. In this study, polyethylene glycol (PEG-6000 with MW ~6000 g/mol as the soft segment and diisocyanate as the hard segment were used to synthesize SMPUs, and the results were compared with the SMPUs with polycaprolactone PCL-2000. The study revealed that although the PEG-6000-based SMPUs have lower maximum elongations at break (425% and recovery stresses than those of PCL-based SMPUs, they have much better recovery ratios (up to 98% and shape fixity (up to 95%, hence better shape memory effect. Furthermore, PEG-based SMPUs showed a much shorter actuation time of < 10 s for up to 90% shape recovery compared to typical actuation times of tens of seconds to a few minutes for common SMPUs, demonstrated their great potential for applications in microsystems and other engineering components.

  19. Synaptic effects of low molecular weight components from Chilean Black Widow spider venom.

    Science.gov (United States)

    Parodi, Jorge; Romero, Fernando

    2008-11-01

    alpha-Latrotoxin is the principal component of the venom from the euroasiatic Black Widow spider and has been studied for its pharmacological use as a synaptic modulator. Interestingly, smaller molecular weight fractions have been found to be associated with this toxin, but their cellular actions have not been studied in detail. The venom from the Chilean Black Widow spider (Latrodectus mactans) does not produce alpha-latrotoxin, however it does contain several small polypeptides. We have recently demonstrated cellular effects of these peptides at the synaptic level using whole-cell patch clamp techniques. Purified venom from the glands of L. mactans was studied in 12 DIV rat hippocampal neuronal cultures. Venom at a concentration of 10nM was able to decrease neuronal conductance thereby increasing membrane resistance. This effect on the passive properties of the neurons induced a change in action potential kinetics simulating the action of classic potassium channel blockers. These changes produced an increase in spontaneous synaptic activity in rat hippocampal cultures in the presence of the venom in a concentration- and time-dependent manner. These results indicate that venom from Chilean spider L. mactans is capable of increasing cell membrane resistance, prolonging the action potential and generating an increase in synaptic activity demonstrating an interesting pharmacological effect of these low molecular weight fragments.

  20. Insights into the Toxicological Properties of a Low Molecular Weight Fraction from Zoanthus sociatus (Cnidaria

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    Agostinho Antunes

    2013-08-01

    Full Text Available The phylum Cnidaria is an ancient group of venomous animals, specialized in the production and delivery of toxins. Many species belonging to the class Anthozoa have been studied and their venoms often contain a group of peptides, less than 10 kDa, that act upon ion channels. These peptides and their targets interact with high affinity producing neurotoxic and cardiotoxic effects, and even death, depending on the dose and the administration pathway. Zoanthiniaria is an order of the Subclass Hexacorallia, class Anthozoa, and unlike sea anemone (order Actiniaria, neither its diversity of toxins nor the in vivo effects of the venoms has been exhaustively explored. In this study we assessed some toxicological tests on mice with a low molecular weight fraction obtained by gel filtration in Sephadex G-50 from Zoanthus sociatus crude extract. The gel filtration chromatogram at 280 nm revealed two major peaks, the highest absorbance corresponding to the low molecular weight fraction. The toxicological effects seem to be mostly autonomic and cardiotoxic, causing death in a dose dependent manner with a LD50 of 792 μg/kg. Moreover, at a dose of 600 μg/kg the active fraction accelerated the KCl-induced lethality in mice.

  1. Equal channel angular extrusion of ultra-high molecular weight polyethylene

    International Nuclear Information System (INIS)

    Reinitz, Steven D.; Engler, Alexander J.; Carlson, Evan M.; Van Citters, Douglas W.

    2016-01-01

    Ultra-high molecular weight polyethylene (UHMWPE), a common bearing surface in total joint arthroplasty, is subject to material property tradeoffs associated with conventional processing techniques. For orthopaedic applications, radiation-induced cross-linking is used to enhance the wear resistance of the material, but cross-linking also restricts relative chain movement in the amorphous regions and hence decreases toughness. Equal Channel Angular Extrusion (ECAE) is proposed as a novel mechanism by which entanglements can be introduced to the polymer bulk during consolidation, with the aim of imparting the same tribological benefits of conventional processing without complete inhibition of chain motion. ECAE processing at temperatures near the crystalline melt for UHMWPE produces (1) increased entanglements compared to control materials; (2) increasing entanglements with increasing temperature; and (3) mechanical properties between values for untreated polyethylene and for cross-linked polyethylene. These results support additional research in ECAE-processed UHMWPE for joint arthroplasty applications. - Highlights: • A new processing method for ultra-high molecular weight polyethylene is introduced. • The process produces a highly entangled polyethylene material. • Entanglements are hypothesized to enhance the wear resistance of polyethylene. • This process eliminates the trade-off between mechanical and wear properties.

  2. Molecular Weight, Protein Binding Affinity and Methane Mitigation of Condensed Tannins from Mangosteen-peel (

    Directory of Open Access Journals (Sweden)

    P. Paengkoum

    2015-10-01

    Full Text Available The objectives of this study were to determine the molecular weight of condensed tannins (CT extracted from mangosteen (Garcinia mangostana L peel, its protein binding affinity and effects on fermentation parameters including total gas, methane (CH4 and volatile fatty acids (VFA production. The average molecular weight (Mw of the purified CT was 2,081 Da with a protein binding affinity of 0.69 (the amount needed to bind half the maximum bovine serum albumin. In vitro gas production declined by 0.409, 0.121, and 0.311, respectively, while CH4 production decreased by 0.211, 0.353, and 0.549, respectively, with addition of 10, 20, and 30 mg CT/500 mg dry matter (DM compared to the control (p<0.05. The effects of CT from mangosteen-peel on in vitro DM degradability (IVDMD and in vitro N degradability was negative and linear (p<0.01. Total VFA, concentrations of acetic, propionic, butyric and isovaleric acids decreased linearly with increasing amount of CT. The aforementioned results show that protein binding affinity of CT from mangosteen-peel is lower than those reported for Leucaena forages, however, the former has stronger negative effect on IVDMD. Therefore, the use of mangosteen-peel as protein source and CH4 mitigating agent in ruminant feed requires further investigations.

  3. Hyaluronic acid-coated chitosan nanoparticles: molecular weight-dependent effects on morphology and hyaluronic acid presentation.

    Science.gov (United States)

    Almalik, Abdulaziz; Donno, Roberto; Cadman, Christopher J; Cellesi, Francesco; Day, Philip J; Tirelli, Nicola

    2013-12-28

    Chitosan nanoparticles are popular carriers for the delivery of macromolecular payloads, e.g. nucleic acids. In this study, nanoparticles were prepared via complexation with triphosphate (TPP) anions and were successively coated with hyaluronic acid (HA). Key variables of the preparative process (e.g. chitosan and HA molecular weight) were optimised in view of the maximisation of loading with DNA, of the Zeta potential and of the dimensional stability, and the resulting particles showed excellent storage stability. We have focused on the influence of chitosan molecular weight on nanoparticle properties. Larger molecular weight increased their porosity (=decreased cross-link density), and this caused also larger dimensional changes in response to variations in osmotic pressure or upon drying. The dependency of nanoparticle porosity on chitosan molecular weight had a profound effect on the adsorption of HA on the nanoparticles; HA was apparently able to penetrate deeply into the more porous high molecular weight (684 kDa) chitosan nanoparticles, while it formed a corona around those composed of more densely cross-linked low molecular weight (25 kDa) chitosan. Atomic Force Microscopy (AFM) allowed not only to highlight the presence of this corona, but also to estimate its apparent thickness to about 20-30 nm (in a dry state). The different morphology has a significant effect on the way HA is presented to biomolecules, and this has specific relevance in relation to interactions with HA receptors (e.g. CD44) that influence kinetics and mechanism of nanoparticle uptake. Finally, it is worth to mention that chitosan molecular weight did not appear to greatly affect the efficiency of nanoparticle loading with DNA, but significantly influenced its chitosanase-triggered release, with high molecular chitosan nanoparticles seemingly more prone to degradation by this enzyme. © 2013.

  4. Dextran: Influence of Molecular Weight in Antioxidant Properties and Immunomodulatory Potential

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    Vinicius C. Soeiro

    2016-08-01

    Full Text Available Dextrans (α-d-glucans extracted from Leuconostoc mesenteroides, with molecular weights (MW of 10 (D10, 40 (D40 and 147 (D147 kDa, were evaluated as antioxidant, anticoagulant and immunomodulatory drugs for the first time. None presented anticoagulant activity. As for the antioxidant and immunomodulatory tests, a specific test showed an increase in the dextran activity that was proportional to the increase in molecular weight. In a different assay, however, activity decreased or showed no correlation to the MW. As an example, the reducing power assay showed that D147 was twice as potent as other dextrans. On the other hand, all three samples showed similar activity (50% when it came to scavenging the OH radical, whereas only the D10 sample showed sharp activity (50% when it came to scavenging the superoxide ion. D40 was the single dextran that presented with immunomodulatory features since it stimulated the proliferation (~50% of murine macrophages (RAW 264.7 and decreased the release of nitric oxide (~40% by the cells, both in the absence and presence of lipopolysaccharides (LPS. In addition, D40 showed a greater scavenging activity (50% for the hydrogen peroxide, which caused it to also be the more potent dextran when it came to inhibiting lipid peroxidation (70%. These points toward dextrans with a 40 kDa weight as being ideal for antioxidant and immunomodulatory use. However, future studies with the D40 and other similarly 40 kDa dextrans are underway to confirm this hypothesis.

  5. Molecular weight evaluation of poly-dimethylsiloxane on solid surfaces using silver deposition/TOF-SIMS

    Science.gov (United States)

    Inoue, Masae; Murase, Atsushi

    2004-06-01

    Molecular ions include information about end groups, functional groups and molecular weight. A method for directly detecting this in the high-mass region of the spectrum (>1000 amu) from poly-dimethylsiloxane (PDMS) on a solid surface was investigated. It was found that a TOF-SIMS analysis of silver-deposited surfaces (silver deposition/TOF-SIMS) is useful for this purpose. Two methods for silver deposition, the diode sputtering method and the vacuum evaporation coating method, were tried. The former required the sample to be cooled so as to prevent the damage of the sample surface due to thermal oxidation; the latter caused no damage to sample surfaces at room temperature. Using silver deposition/TOF-SIMS analysis, silver-cationized quasi-molecular ions were clearly detected from PDMS on solid surfaces and their images were observed without the interference of deposited silver. By applying to the analysis of paint defects, etc., it was confirmed that this technique is useful to analyze practical industrial materials. Silver-cationized ions were detected not only from PDMS, but also from other organic materials, such as some kinds of lubricant additives and fluorine oils on solid surfaces. Therefore, silver deposition/TOF-SIMS was proved to be useful for the analysis of thin substances on solid surfaces.

  6. Absolute nuclear material assay

    Science.gov (United States)

    Prasad, Manoj K [Pleasanton, CA; Snyderman, Neal J [Berkeley, CA; Rowland, Mark S [Alamo, CA

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  7. Absolute nuclear material assay

    Science.gov (United States)

    Prasad, Manoj K [Pleasanton, CA; Snyderman, Neal J [Berkeley, CA; Rowland, Mark S [Alamo, CA

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  8. Development of solvent-free offset ink using vegetable oil esters and high molecular-weight resin.

    Science.gov (United States)

    Park, Jung Min; Kim, Young Han; Kim, Sung Bin

    2013-01-01

    In the development of solvent-free offset ink, the roles of resin molecular weight and used solvent on the ink performance were evaluated by examining the relationship between the various properties of resin and solvent and print quality. To find the best performing resin, the soy-oil fatty acid methyl ester (FAME) was applied to the five modified-phenolic resins having different molecular weights. It is found from the experimental results that the ink made of higher molecular weight and better solubility resin gives better printability and print quality. It is because larger molecular weight resin with better solubility gives higher rate of ink transfer. From the ink application of different esters to high molecular weight resin, the best printing performance was yielded from the soy-oil fatty acid butyl ester (FABE). It is due to its high kinematic viscosity resulting in the smallest change of ink transfer weight upon multiple number of printing, which improves the stability of ink quality.

  9. Synthesis and characterization of sugar based low molecular weight gelators and the preparation of chiral sulfinamides

    Science.gov (United States)

    Mangunuru, Hari Prasad Reddy

    Low molecular weight gelators (LMWGs) have received considerable attention in the field of chemistry from last few decades. These compounds form self-assembled fibrous networks like micelles, cylindrical, sheets, fibers, layers and so on. The fibrous network entraps the solvent and forms gel, because of the self-assembly phenomenon and their demonstrated potential uses in a variety of areas, ranging from environmental to medicinal applications. Sugars are good starting materials to synthesize the new class of LMWG's, because these are different from some expensive materials, these are natural products. We have synthesized and characterized the LMGS's based on D-glucose and D-glucosamine. D-glucosamine is the versatile starting material to make different peptoids and triazoles. Several series of compounds were synthesized using compounds 1-3 as starting material and studied the gelation behavior all the compounds. We have studied the self-assembling properties of a new class of tripeptoids, synthesized by one-pot Ugi reaction from simple starting materials. Among the focused library of tripeptoids synthesized, we found that several efficient low molecular weight organogelators were obtained for aqueous DMSO and ethanol mixtures. We have also synthesized and characterized a series of monosaccharide triazole derivatives. These compounds were synthesized from N-acetyl glucosamine and D-glucose via a Cu(I) catalyzed azide/alkyne cycloaddition reaction (CuAAc). The compounds have been screened for their gelation properties and several efficient low molecular weight organo/hydro gelators were obtained, among these compounds, five per-acetyl glucosamine derivatives and one peracetyl glucose derivative were able to form gels in water. These new molecules are expected to be useful in drug delivery and tissue engineering.*. Asymmetric synthesis of chiral amines is a challenging in synthetic organic chemistry. The development of new catalysts for asymmetric organic

  10. The Potency of Hyaluronan of Different Molecular Weights in the Stimulation of Blood Phagocytes

    Directory of Open Access Journals (Sweden)

    Barbora Safrankova

    2010-01-01

    Full Text Available The regulatory functions of glycosaminoglycan hyaluronan (HA are suggested to be dependent on its molecular weight (MW. Proinflammatory and stimulatory effects are proposed mainly for the low MW HA. However, the complex response of blood phagocytes to HA of different MW is unclear. Herein, the effects of highly purified HA of precisely defined MW (52, 250, and 970 kDa on human blood phagocytes were tested. All MW HA activated blood phagocytes, including the spontaneous production of ROS, degranulation, and the production of tumor necrosis factor alpha, with low MW HA 52 kDa having the highest potency and high MW HA 970 kDa having the lowest potency. Interestingly, HA inhibited ROS production stimulated by opsonized zymosan particles and, in contrast, potentiated starch-activated ROS production, mostly independent of MW. Data showed a significant effect of HA of different MW on blood phagocytes, including high MW HA.

  11. The potency of hyaluronan of different molecular weights in the stimulation of blood phagocytes.

    Science.gov (United States)

    Safrankova, Barbora; Gajdova, Silvie; Kubala, Lukas

    2010-01-01

    The regulatory functions of glycosaminoglycan hyaluronan (HA) are suggested to be dependent on its molecular weight (MW). Proinflammatory and stimulatory effects are proposed mainly for the low MW HA. However, the complex response of blood phagocytes to HA of different MW is unclear. Herein, the effects of highly purified HA of precisely defined MW (52, 250, and 970  kDa) on human blood phagocytes were tested. All MW HA activated blood phagocytes, including the spontaneous production of ROS, degranulation, and the production of tumor necrosis factor alpha, with low MW HA 52  kDa having the highest potency and high MW HA 970  kDa having the lowest potency. Interestingly, HA inhibited ROS production stimulated by opsonized zymosan particles and, in contrast, potentiated starch-activated ROS production, mostly independent of MW. Data showed a significant effect of HA of different MW on blood phagocytes, including high MW HA.

  12. Biomimetic studies of wood decay: Simulating the effect of low molecular weight compounds and fungal enzymes

    DEFF Research Database (Denmark)

    Hastrup, Anne Christine Steenkjær; Howell, Caitlin; Jellison, Jody

    The effect of FeCl3 (Fe3+), hydrogen peroxide (H2O2), a low molecular weight compound (2,3- Dihydroxybenzoic acid), and oxalic acid on wood were tested in a study designed to mimic wood degradation by brown rot fungi. Previous studies suggest that these components are involved in the early stages...... of brown rot decay where they catalyze the formation of hydroxyl radicals through the Fenton reaction or related mechanisms. However, the separate and combined effects of these individual chemical components on wood have not been thoroughly investigated. Tests were conducted in Erlenmeyer flasks containing...... 50 ml of 40 mM acetate buffer (pH 4.5), white pine wood powder and varying combinations of the chemicals previously mentioned. Changes in cellulose crystallinity were analyzed by X-ray diffraction using a ¿-2¿ scan. Findings suggest that iron, H2O2, chelators and oxalic acid may affect over all...

  13. Toxicological Evaluation of Low Molecular Weight Fucoidan in Vitro and in Vivo

    Directory of Open Access Journals (Sweden)

    Pai-An Hwang

    2016-06-01

    Full Text Available For a long time, fucoidan has been well known for its pharmacological activities, and recently low molecular weight fucoidan (LMF has been used in food supplements and pharmaceutical products. In the present study, LMF was extracted from Laminaria japonica by enzyme hydrolysis. The toxicity of LMF in mouse and rat models was determined by many methods, such as total arsenic content, bacterial reverse mutation assay, chromosome aberration assay, and in vivo micronucleus assay. The present findings showed that LMF at 5000 μg/mL exhibited no mutagenicity. It also produced no formatting disruption of red blood cells in vivo. At 2000 mg/kg BW/day there were no toxicological indications. LMF is expected to be used as a safe food supplement.

  14. Biomimetic studies of wood decay: Simulating the effect of low molecular weight compounds and fungal enzymes

    DEFF Research Database (Denmark)

    Hastrup, Anne Christine Steenkjær; Howell, Caitlin; Jellison, Jody

    50 ml of 40 mM acetate buffer (pH 4.5), white pine wood powder and varying combinations of the chemicals previously mentioned. Changes in cellulose crystallinity were analyzed by X-ray diffraction using a ¿-2¿ scan. Findings suggest that iron, H2O2, chelators and oxalic acid may affect over all......The effect of FeCl3 (Fe3+), hydrogen peroxide (H2O2), a low molecular weight compound (2,3- Dihydroxybenzoic acid), and oxalic acid on wood were tested in a study designed to mimic wood degradation by brown rot fungi. Previous studies suggest that these components are involved in the early stages...... of brown rot decay where they catalyze the formation of hydroxyl radicals through the Fenton reaction or related mechanisms. However, the separate and combined effects of these individual chemical components on wood have not been thoroughly investigated. Tests were conducted in Erlenmeyer flasks containing...

  15. Directing filtration to narrow molecular weight distribution of oligodextran in an enzymatic membrane reactor

    DEFF Research Database (Denmark)

    Su, Ziran; Luo, Jianquan; Pinelo, Manuel

    2018-01-01

    product, hypersaline wastewater discharge and potential safety hazards. In this work, a novel enzymatic membrane reactor (EMR) system to produce oligodextran is proposed, whereby in-situ product recovery can be manipulated to control the Mw distribution of the resulting products. Results showed......Oligodextrans with molecular weight (Mw) within the range of 5.0–8.0kDa have great commercial potential as precursors of iron-dextran for anemia treatment. Traditional oligodextran production consists of sucrose fermentation, acid hydrolysis and ethanol precipitation, which results in an uneven Mw...... narrow distribution and high productivity. Moreover, high transmembrane pressures (3 bars) and low stirring rates (160rpm) promoted yields beyond 50% in 120min. Higher permeate fluxes prevented further product hydrolysis and enhanced the yield. However, the resulting concentration polarization (CP...

  16. Photoluminescence Properties of Polymorphic Modifications of Low Molecular Weight Poly(3-hexylthiophene)

    Science.gov (United States)

    Kobayashi, Takashi; Kinoshita, Keita; Niwa, Akitsugu; Nagase, Takashi; Naito, Hiroyoshi

    2017-05-01

    The structural and photoluminescence (PL) properties of thin films of poly(3-hexylthophene) (P3HT) with molecular weights (MWs) of 3000 and 13,300 have been investigated. Although high MW P3HT always self-organizes into one packing structure (form I), low MW P3HT forms two different packing structures (forms I and II) depending on the fabrication conditions. In this work, several fabrication techniques have been examined to obtain form II samples with little inclusion of a form I component. It is found that drop-cast thin films of low MW P3HT (form II) exhibit a PL spectrum that is different from that of form I and does not contain the form I component. The PL spectrum can thus be attributed to form II. The differences in PL properties between forms I and II can be understood in terms of weakened interchain interactions due to the longer interchain distance in form II.

  17. Skin: Major target organ of allergic reactions to small molecular weight compounds

    International Nuclear Information System (INIS)

    Merk, Hans F.; Baron, Jens M.; Neis, Mark M.; Obrigkeit, Daniela Hoeller; Karlberg, Ann-Therese

    2007-01-01

    Skin is a major target organ for allergic reactions to small molecular weight compounds. Drug allergic reactions may be life-threatening such as in the case of anaphylactic reactions or bullous drug reactions and occur in about 5% of all hospitalized patients. Allergic contact dermatitis has an enormous influence on the social life of the patient because it is the most frequent reason for occupational skin diseases and the treatment and prevention of this disease cost approximately Euro 3 billion per year in Germany. The different proposed pathophysiological pathways leading to a drug eruption are discussed in this paper. All major enzymes which are involved in the metabolism of xenobiotica were shown to be present in skin. Evidence supporting the role of metabolism in the development of drug allergy and allergic contact dermatitis is demonstrated in the example of sulphonamides and fragrances

  18. Possible hypoglycemic effect of Aloe vera L. high molecular weight fractions on type 2 diabetic patients

    Science.gov (United States)

    Yagi, Akira; Hegazy, Sahar; Kabbash, Amal; Wahab, Engy Abd-El

    2009-01-01

    Aloe vera L. high molecular weight fractions (AHM) containing less than 10 ppm of barbaloin and polysaccharide (MW: 1000 kDa) with glycoprotein, verectin (MW: 29 kDa), were prepared by patented hyper-dry system in combination of freeze–dry technique with microwave and far infrared radiation. AHM produced significant decrease in blood glucose level sustained for 6 weeks of the start of the study. Significant decrease in triglycerides was only observed 4 weeks after treatment and continued thereafter. No deterious effects on kidney and liver functions were apparent. Treatment of diabetic patients with AHM may relief vascular complications probably via activation of immunosystem. PMID:23964163

  19. Synthesis of a high molecular weight thyroglobulin dimer by two ovine thyroid cell lines: the OVNIS.

    Science.gov (United States)

    Hovsépian, S; Aouani, A; Fayet, G

    1986-05-01

    The OVNIS 6H and 5H thyroid cells, 2 permanent cell lines isolated 3 years ago from ovine tissue, synthesize a high molecular weight glycosylated protein, immunologically related to ovine thyroglobulin, which is similar to the prothyroid hormone dimer (17-19) S: thyroglobulin. Using sucrose gradient centrifugation and cell labelling with [14C]Leu or [3H]GlNH2, radioactivity was observed in proteins purified from cell layers and from cell culture media. Addition of thyrotropin to or removal from the media resulted respectively in an increase (+773%) or decrease (-1090%) of the total radioactivity detected in the (17-19)S thyroglobulin fraction. Estimation of thyroglobulin by RIA gave similar though less pronounced effects. These experiments prove (1) that thyroglobulin is still expressed in these OVNIS thyroid cell lines even after 3 years of permanent culture, (2) that TSH modulates the level of this protein through a TSH-receptor functional system.

  20. Determination of free inositols and other low molecular weight carbohydrates in vegetables.

    Science.gov (United States)

    Hernández-Hernández, Oswaldo; Ruiz-Aceituno, Laura; Sanz, María Luz; Martínez-Castro, Isabel

    2011-03-23

    Different low molecular weight carbohydrates including saccharides, polyalcohols, sugar acids, and glycosides have been identified and quantified in different edible vegetables from Asteraceae, Amarantaceae, Amarylidaceae, Brassicaceae, Dioscoreaceae, and Solanaceae families by gas chromatography-mass spectrometry. Apart from glucose, fructose, and sucrose, other saccharides such as sedoheptulose in chicory, spinach, cabbage, purple yam, eggplant, radish, and oak leaf lettuce, rutinose in eggplant skin, and a glycosyl-inositol in spinach have been identified. chiro-Inositol was found in all vegetables of the Asteraceae family (3.1-32.6 mg 100 g(-1)), whereas scyllo-inositol was detected in those of purple yam, eggplant, artichoke, chicory, escarole, and endive (traces-23.2 mg 100 g(-1)). α-Galactosides, kestose, glucaric acid, and glycosyl-glycerols were also identified and quantified in some of the analyzed vegetables. Considering the bioactivity of most of these compounds, mainly chicory leaves, artichokes, lettuces, and purple yam could constitute beneficial sources for human health.

  1. A novel hypotonic sports drink containing a high molecular weight polysaccharide.

    Science.gov (United States)

    Hao, Limin; Chen, Qiang; Lu, Jike; Li, Zhiyu; Guo, Changjiang; Qian, Ping; Yu, Jianyong; Xing, Xinhui

    2014-05-01

    Carbohydrate consumption during exercise can improve performance and delay the onset of fatigue. The purpose of this study was to develop a novel sports drink powder, Jxdrink, containing the high molecular weight polysaccharide Jxsac. Animal experiments including digestion and exhaustive swimming experiments were conducted to observe the physiological effects of this beverage. Human experiments involved the participation of 10 healthy male athletes completing a 180 km road cycling test. The osmolality of Jxdrink was 170-175 mosmol kg(-1), lower than that of human blood. Jxdrink was found to prolong the exhaustive swimming time in test animals. Moreover, Jxdrink had a relatively high glycemic index that maintained blood glucose levels during human cycling experiments. Thus, Jxdrink was found to effectively delay the onset of fatigue in both human and animal experiments.

  2. Microstructure, molecular weight and thermal behavior of natural rubber (NR) from mangabeira (Hancornia speciosa)

    International Nuclear Information System (INIS)

    Santos, Expedito Flavio dos; Feitosa, Judith P.A.; Ricardo, Nagila M.P.S.

    2001-01-01

    The natural rubber (NR) from Hancornia speciosa contains characteristics that turns it a good alternative in elastomers supply. The NMR and IR spectra showed that the rubber of mangabeira is composed fundamentally by poly(1,4-cis-isoprene). The rubber molecular weight obtained by GPC and viscometry was 2,0x10 6 and 1,3x10 6 g/mol, respectively, in good agreement with the values determined for seringueira and manicoba NR. The glass transition temperature obtained by DSC (Tg = - 65 deg C) showed the mangabeira rubber is ideal to be utilized in regions of cold climate without compromising its mechanical properties. The rubber has also good thermal stability up to 213 deg C, as indicated by TG curves. This results indicated that the mangabeira NR can be effectively used in vulcanized articles or to be added to asphalt. (author)

  3. Ballistic behavior of ultra-high molecular weight polyethylene composite: effect of gamma radiation

    International Nuclear Information System (INIS)

    Alves, Andreia L. dos Santos; Nascimento, Lucio F.C.; Suarez, Joao C. Miguez; lucio2002bol.com.br

    2003-01-01

    Since World War II, textile composites have been used as ballistic armor. Ultra-high molecular weight polyethylene (UHMWPE) fibers are used in the production of armor materials. As they have been developed and commercialized only recently, there is not enough information about the effect of environmental agents in the ballistic performance of UHMWPE composites. In the present work, was evaluated the ballistic behavior of composite plates manufactured with UHMWPE fibers after exposure to gamma radiation. The ballistic tests results were related to the macromolecular alterations induced by the radiation through mechanical (hardness, impact and flexure) and physicochemical (Ftir/Mir. DSC and TGA) testing. It was observed that irradiation induces changes in the UHMWPE, degrading the ballistic performance of the composite. These results are presented and discussed. (author)

  4. Surface free energy of ultra-high molecular weight polyethylene modified by electron and gamma irradiation

    International Nuclear Information System (INIS)

    Abdul-Kader, A.M.; Turos, A.; Radwan, R.M.; Kelany, A.M.

    2009-01-01

    Surface free energy of biocompatible polymers is important factor which affects the surface properties such as wetting, adhesion and biocompatibility. In the present work, the change in the surface free energy of ultra-high molecular weight polyethylene (UHMWPE) samples, which is produced by electron beam and gamma ray irradiation were, investigated. Mechanism of the changes in surface free energy induced by irradiations of doses ranging from 25 to 500 kGy was studied. FTIR technique was applied for sample analysis. Contact angle measurements showed that wettability and surface free energy of samples have increased with increasing the irradiation dose, where the values of droplet contact angle of the samples decrease gradually with increasing the radiation dose. The increase in the wettability and surface free energy of the irradiated samples are attributed to formation of hydrophilic groups on the polymer surface by the oxidation, which apparently occurs by exposure of irradiated samples to the air.

  5. Supramolecular Structure and Mechanical Characteristics of Ultrahigh-Molecular-Weight Polyethylene-Inorganic Nanoparticle Nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Okhlopkova, T. A.; Borisova, R. V.; Nikiforov, L. A.; Spiridonov, A. M.; Okhlopkova, A. A.; Cho, Jin-Ho [North-Eastern Federal University, Yakutsk (Russian Federation); Jeong, Dae-Yong [Inha University, Incheon (Korea, Republic of)

    2016-04-15

    We investigated the mechanical properties and structure of polymeric nanocomposites (PNCs) with anultrahigh-molecular-weight polyethylene (UHMWPE) matrix and aluminum and silicon oxide and nitride nanoparticle (NP) fillers. Mixing with a paddle mixer or by joint mechanical activation in a planetary mill was used for the PNC preparation. Joint mechanical activation afforded PNCs with better mechanical properties than paddle mixing. Scanning electron microscopy suggested that the poorer mechanical properties can be attributed to the disordered regions and imperfect spherulites in the PNC supramolecular structure arising from paddle mixing. The better mechanical properties observed with joint mechanical activation may derive from the uniform NP distribution in the polymer matrix and absence of disordered regions.

  6. Determination of nanoparticle size distribution together with density or molecular weight by 2D analytical ultracentrifugation

    KAUST Repository

    Carney, Randy P.

    2011-06-07

    Nanoparticles are finding many research and industrial applications, yet their characterization remains a challenge. Their cores are often polydisperse and coated by a stabilizing shell that varies in size and composition. No single technique can characterize both the size distribution and the nature of the shell. Advances in analytical ultracentrifugation allow for the extraction of the sedimentation (s) and diffusion coefficients (D). Here we report an approach to transform the s and D distributions of nanoparticles in solution into precise molecular weight (M), density (?P) and particle diameter (dp) distributions. M for mixtures of discrete nanocrystals is found within 4% of the known quantities. The accuracy and the density information we achieve on nanoparticles are unparalleled. A single experimental run is sufficient for full nanoparticle characterization, without the need for standards or other auxiliary measurements. We believe that our method is of general applicability and we discuss its limitations. 2011 Macmillan Publishers Limited. All rights reserved.

  7. Spontaneous Hemocholecyst in an End-Stage Renal Failure Patient on Low Molecular Weight Heparin Hemodialysis

    Directory of Open Access Journals (Sweden)

    Konstantinos Blouhos

    2012-01-01

    Full Text Available The present paper describes a case of spontaneous hemocholecyst in a patient with end-stage renal failure on low molecular weight heparin hemodialysis. The patient presented with acute right upper quadrant pain. An initial ultrasound scan demonstrated a distended gallbladder containing echogenic bile without stones. During hospitalization the patient became febrile, and jaundiced, developed leukocytosis, and had an elevation in serum bilirubin, transaminases, and alkaline phosphatase. A new ultrasound demonstrated a thick-walled gallbladder containing echogenic bile and pericholecystic fluid. MRI depicted a distended gallbladder containing material of mixed signal intensity and a normal biliary tract. Open cholecystectomy revealed a gallbladder filled with blood and clots, and transcystic common bile duct exploration flushed blood clots out of the bile duct. To our knowledge this is the second case of spontaneous hemocholecyst reported in the literature as a consequence of uremic bleeding and LMWH hemodialysis in the absence of other pathology.

  8. The physical and chemical properties of plasma treated ultra-high-molecular-weight polyethylene fibers

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Teodoru, Steluta; Hansen, Charles M.

    2011-01-01

    polymer assures maximum physical adhesion to transfer loads uniformly. Plasma treatment of ultra-high-molecular-weight polyethylene (UHMWPE) fibers is shown to significantly increase the amount of oxygen in the surface. There are two distinct types of surfaces in both the plasma treated and the untreated......A uniform and smooth transfer of stresses across the polymer matrix/fiber interface is enhanced when adhesion between the matrix and fiber surface is optimized. In the absence of covalent bonds matching the Hansen solubility (cohesion) parameters (HSP) of the fiber surface with the HSP of a matrix...... UHMWPE fibers. One type is typical of polyethylene (PE) polymers while the other is characteristic of the oxygenated surface at much higher values of HSP. The oxygenated surface of the plasma treated fibers has the HSP δD, δP, and δH equal to 16.5, 15.3, and 8.2, compared to the pure PE surface with HSP...

  9. Enhancing Accuracy in Molecular Weight Determination of Highly Heterogeneously Glycosylated Proteins by Native Tandem Mass Spectrometry.

    Science.gov (United States)

    Wang, Guanbo; de Jong, Rob N; van den Bremer, Ewald T J; Parren, Paul W H I; Heck, Albert J R

    2017-05-02

    The determination of molecular weights (MWs) of heavily glycosylated proteins is seriously hampered by the physicochemical characteristics and heterogeneity of the attached carbohydrates. Glycosylation impacts protein migration during sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) and size-exclusion chromatography (SEC) analysis. Standard electrospray ionization (ESI)-mass spectrometry does not provide a direct solution as this approach is hindered by extensive interference of ion signals caused by closely spaced charge states of broadly distributed glycoforms. Here, we introduce a native tandem MS-based approach, enabling charge-state resolution and charge assignment of protein ions including those that escape mass analysis under standard MS conditions. Using this method, we determined the MW of two model glycoproteins, the extra-cellular domains of the highly and heterogeneously glycosylated proteins CD38 and epidermal growth factor receptor (EGFR), as well as the overall MW and binding stoichiometries of these proteins in complex with a specific antibody.

  10. In vivo endothelial siRNA delivery using polymeric nanoparticles with low molecular weight

    Science.gov (United States)

    Dahlman, James E.; Barnes, Carmen; Khan, Omar F.; Thiriot, Aude; Jhunjunwala, Siddharth; Shaw, Taylor E.; Xing, Yiping; Sager, Hendrik B.; Sahay, Gaurav; Speciner, Lauren; Bader, Andrew; Bogorad, Roman L.; Yin, Hao; Racie, Tim; Dong, Yizhou; Jiang, Shan; Seedorf, Danielle; Dave, Apeksha; Singh Sandhu, Kamaljeet; Webber, Matthew J.; Novobrantseva, Tatiana; Ruda, Vera M.; Lytton-Jean, Abigail K. R.; Levins, Christopher G.; Kalish, Brian; Mudge, Dayna K.; Perez, Mario; Abezgauz, Ludmila; Dutta, Partha; Smith, Lynelle; Charisse, Klaus; Kieran, Mark W.; Fitzgerald, Kevin; Nahrendorf, Matthias; Danino, Dganit; Tuder, Rubin M.; von Andrian, Ulrich H.; Akinc, Akin; Panigrahy, Dipak; Schroeder, Avi; Koteliansky, Victor; Langer, Robert; Anderson, Daniel G.

    2014-08-01

    Dysfunctional endothelium contributes to more diseases than any other tissue in the body. Small interfering RNAs (siRNAs) can help in the study and treatment of endothelial cells in vivo by durably silencing multiple genes simultaneously, but efficient siRNA delivery has so far remained challenging. Here, we show that polymeric nanoparticles made of low-molecular-weight polyamines and lipids can deliver siRNA to endothelial cells with high efficiency, thereby facilitating the simultaneous silencing of multiple endothelial genes in vivo. Unlike lipid or lipid-like nanoparticles, this formulation does not significantly reduce gene expression in hepatocytes or immune cells even at the dosage necessary for endothelial gene silencing. These nanoparticles mediate the most durable non-liver silencing reported so far and facilitate the delivery of siRNAs that modify endothelial function in mouse models of vascular permeability, emphysema, primary tumour growth and metastasis.

  11. Low-molecular-weight cyclin E: the missing link between biology and clinical outcome

    International Nuclear Information System (INIS)

    Akli, Said; Keyomarsi, Khandan

    2004-01-01

    Cyclin E, a key mediator of transition during the G 1 /S cellular division phase, is deregulated in a wide variety of human cancers. Our group recently reported that overexpression and generation of low-molecular-weight (LMW) isoforms of cyclin E were associated with poor clinical outcome among breast cancer patients. However, the link between LMW cyclin E biology in mediating a tumorigenic phenotype and clinical outcome is unknown. To address this gap in knowledge, we assessed the role of LMW isoforms in breast cancer cells; we found that these forms of cyclin E induced genomic instability and resistance to p21, p27, and antiestrogens in breast cancer. These findings suggest that high levels of LMW isoforms of cyclin E not only can predict failure to endocrine therapy but also are true prognostic indicators because of their influence on cell proliferation and genetic instability

  12. Identification of components in High Molecular Weight Products: Their properties and mechanism of formation

    DEFF Research Database (Denmark)

    Hjorth, Christian Fogt

    2015-01-01

    forms covalent aggregates during storage. This type of degradation product is termed High Molecular Weight Products (HMWP). As protein aggregates and their immunogenic potential is the subject of increased discussion between academia, industry and pharmaceutical regulators, detailed characterization...... with the covalent link in either the isoAsp form or succinimide form. HMWP species containing deamidation at B3 or desPhe(B1)-N-oxalyl-Val(B2) modification in addition to the covalent link were also identified. The formation pathway was confirmed by insulin analogues with A21Asn->Gly mutations and methylated N......-terminals, which exhibited significantly reduced rate of HMWP formation. The A21Asn-B29Lys HMWP species was isolated and characterized structurally, biophysically and biologically. Insulin HMWP had no residual biological activity and was structurally nearly identical to the non-covalent insulin dimer. HMWP self...

  13. ABSOLUTE NEUTRINO MASSES

    DEFF Research Database (Denmark)

    Schechter, J.; Shahid, M. N.

    2012-01-01

    We discuss the possibility of using experiments timing the propagation of neutrino beams over large distances to help determine the absolute masses of the three neutrinos.......We discuss the possibility of using experiments timing the propagation of neutrino beams over large distances to help determine the absolute masses of the three neutrinos....

  14. Molecular weight controllable degradation of Laminaria japonica polysaccharides and its antioxidant properties

    Science.gov (United States)

    Zha, Shenghua; Zhao, Qingsheng; Zhao, Bing; Ouyang, Jie; Mo, Jianling; Chen, Jinjin; Cao, Lili; Zhang, Hong

    2016-08-01

    In this study, molecular weight controllable degradation of algal Laminaria japonica polysaccharides (LPS) was investigated by ultrasound combined with hydrogen peroxide. Three main factors, i.e., ultrasonic power (A), ultrasonic time (B), and H2O2 concentration (C) were chosen for optimizing parameters by employing three-factors, three-levels BBD. The influence of degradation on structure change and antioxidant activities was also investigated. A second-order polynomial equation including molecular weight (Y) of Laminaria japonica polysaccharides and each variable parameter, i.e., ultrasonic power (A), ultrasonic time (B), and H2O2 concentration (C), was established: Y=20718.67-4273.13 A-4000.38 B-1438.75 C+2333.25 AB+1511.00 AC+873.00 BC+2838.29 A 2 + 2490.79 B 2+873.04 C 2. The equation regression coefficient value ( R 2 = 0.969) indicated that this equation was valid. The value of the adjusted determination coefficient (adjusted R 2 = 0.914) also confirmed that the model was highly significant. The results of selected experimental degradation conditions matched with the predicted value. FT-IR spectra revealed that the structures of LPS before and after degradation were not significantly changed. Antioxidant activities of LPS revealed that low Mws possessed stronger inhibitory than the original polysaccharides. The scavenging effects on superoxide radicals was the highest when IC50 of crude LPS was 4.92 mg mL-1 and IC50 of Mw 18.576 KDa was 1.02 mg mL-1, which was fourfold higher than initial polysaccharide.

  15. Molecular weight dependence of the morphology in P3HT:PCBM solar cells.

    Science.gov (United States)

    Liu, Feng; Chen, Dian; Wang, Cheng; Luo, Kaiyuan; Gu, Weiyin; Briseno, Alejandro L; Hsu, Julia W P; Russell, Thomas P

    2014-11-26

    In polymer-based photovoltaic devices, optimizing and controlling the active layer morphology is important to enhancing the device efficiency. Using poly(3-hexylthiophene) (P3HT) with well-defined molecular weights (MWs), synthesized by the Grignard metathesis (GRIM) method, we show that the morphology of the photovoltaic active layer and the absorption and crystal structure of P3HT are dependent on the MW. Differential scanning calorimetry showed that the crystallinity of P3HT reached a maximum for intermediate MWs. Grazing-incidence wide-angle X-ray diffraction showed that the spacing of the (100) planes of P3HT increased with increasing MW, while the crystal size decreased. Nonlinear crystal lattice expansions were found for both the (100) and (020) lattice planes, with an unusual π-π-stacking enhancement observed between 50 and 100 °C. The melting point depression for P3HT, when mixed with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), and, hence, the Flory-Huggins interaction parameter depended on the MW. PCBM was found to perturb the ordering of P3HT chains. In photovoltaic devices, P3HT with a MW of ∼20K showed the best device performance. The morphologies of these blends were studied by grazing-incidence small-angle X-ray scattering (GISAXS) and resonant soft X-ray scattering. In GISAXS, we observed that the low-molecular-weight P3HT more readily crystallizes, promoting a phase-separated morphology.

  16. Characterization of high molecular weight cadmium species in contaminated vegetable food

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, K.; Kastenholz, B. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Chemie und Dynamik der Geosphaere 7: Angewandte Physikalische Chemie; Ji, G. [Bonn Univ. (Germany). Lehrstuhl fuer Lebensmittelwissenschaft und Lebensmittelchemie

    2000-10-01

    Spinach and radish grown from seeds were each contaminated with 4 different amounts of cadmium. After a cell breakdown of the eatable parts and centrifugation of the resulting homogenates all supernatants (cytosols) were separated by gel permeation chromatography (GPC). The size-range of the GPC method used was about 20-8000 kDa for globular proteins. The high molecular weight (HMW-Cd-SP, 150-700 kDa) and the low molecular weight Cd species (LMW-Cd-SP, < 150 kDa) in all plant cytosols eluted at about the same retention volume by GPC. The most important Cd binding form in the cytosols of all plants was found to be HMW-Cd-SP. The Cd elution maxima were detected in the range of about 200 kDa. The Cd determinations were performed with ET-AAS by means of matrix modifier. By incubating chosen cytosols with a proteinase before the GPC it was verified that the HMW-Cd-SP in both vegetables are Cd proteins. The molar proportions protein/Cd were about 2-6 in the respective GPC fractions of the HMW-Cd-SP of the highest contaminated plants. The GPC fractions of the HMW-Cd-SP of spinach and radish were further separated by a preparative, native and continuous polyacrylamide gel electrophoresis (PAGE) method. At pH 8 the species were negatively charged, had only a small UV-absorption at 280 nm and showed a very similar elution behavior in all analyzed cytosols. Therefore, we suppose that the HMW-Cd-SP of these two different vegetable foodstuffs have a very similar chemical structure. (orig.)

  17. Impact of Low Molecular Weight Poly(3-hexylthiophene)s as Additives in Organic Photovoltaic Devices.

    Science.gov (United States)

    Seibers, Zach D; Le, Thinh P; Lee, Youngmin; Gomez, Enrique D; Kilbey, S Michael

    2018-01-24

    Despite tremendous progress in using additives to enhance the power conversion efficiency of organic photovoltaic devices, significant challenges remain in controlling the microstructure of the active layer, such as at internal donor-acceptor interfaces. Here, we demonstrate that the addition of low molecular weight poly(3-hexylthiophene)s (low-MW P3HT) to the P3HT/fullerene active layer increases device performance up to 36% over an unmodified control device. Low MW P3HT chains ranging in size from 1.6 to 8.0 kg/mol are blended with 77.5 kg/mol P3HT chains and [6,6]-phenyl C 61 butyric acid methyl ester (PCBM) fullerenes while keeping P3HT/PCBM ratio constant. Optimal photovoltaic device performance increases are obtained for each additive when incorporated into the bulk heterojunction blend at loading levels that are dependent upon additive MW. Small-angle X-ray scattering and energy-filtered transmission electron microscopy imaging reveal that domain sizes are approximately invariant at low loading levels of the low-MW P3HT additive, and wide-angle X-ray scattering suggests that P3HT crystallinity is unaffected by these additives. These results suggest that oligomeric P3HTs compatibilize donor-acceptor interfaces at low loading levels but coarsen domain structures at higher loading levels and they are consistent with recent simulations results. Although results are specific to the P3HT/PCBM system, the notion that low molecular weight additives can enhance photovoltaic device performance generally provides a new opportunity for improving device performance and operating lifetimes.

  18. Mass spectroscopic characteristics of low molecular weight proteins extracted from calcium oxalate stones: preliminary study.

    Science.gov (United States)

    Chen, Wen-Chi; Lai, Chien-Chen; Lai, Chein-Cheng; Tsai, Yuhsin; Tsai, Yu-Hsin; Lin, Wei-Yong; Tsai, Fuu-Jen

    2008-01-01

    It is believed that boundary compositions of matrix proteins might play a role in stone formation; however, few proteomic studies concerning matrix proteins in urinary stones have been conducted. In this study, we extracted low molecular weight proteins from calcium oxalate stones and measured their characteristic patterns by mass spectroscopy. A total of 10 stones were surgically removed from patients with urolithiasis. Proteins were extracted from the stones and identified by one-dimensional electrophoresis (sodium dodecyl sulfate buffer [SDS]-polyacrylamide gel electrophoresis [SDS-PAGE]). After in-gel digest, samples were analyzed by the surface-enhanced laser desorption ionization-time of flight (SELDI-TOF) technique. The peptide sequences were analyzed from the data of mass spectroscopy. Proteins were identified from Database Search (SwissProt Protein Database; Swiss Institute of Bioinformatics; http://www.expasy.org/sprot) on a MASCOT server (Matrix Science Ltd.; http://www.matrixscience.com). A total of three bands of proteins (27, 18, and 14 kDa) were identified from SDS-PAGE in each stone sample. A database search (SwissProt) on a MASCOT server revealed that the most frequently seen proteins from band 1 (27 kDa) were leukocyte elastase precursor, cathepsin G precursor, azurocidin precursor, and myeloblastin precursor (EC 3.4.21.76) (leukocyte proteinase 3); band 2 (18 kDa) comprised calgranulin B, eosinophil cationic protein precursor, and lysozyme C precursor; band 3 (14 kDa) showed neutrophil defensin 3 precursor, calgranulin A, calgranulin C, and histone H4. The modifications and deamidations found from the mass pattern of these proteins may provide information for the study of matrix proteins. Various lower molecular weight proteins can be extracted from calcium oxalate stones. The characteristic patterns and their functions of those proteins should be further tested to investigate their roles in stone formation. (c) 2008 Wiley-Liss, Inc.

  19. Effects of a supersulfated low molecular weight heparin (IK-SSH) on different hemostatic parameters.

    Science.gov (United States)

    Glusa, E; Barthel, W; Schenk, J; Radziwon, P; Butti, A; Markwardt, F; Breddin, K H

    1998-01-01

    In a phase I trial effects of a new supersulfated low molecular weight heparin (IK-SSH) on different hemostatic parameters were investigated in healthy volunteers. Parameters studied were activated partial thromboplastin time (aPTT), thrombin time, Heptest, anti-activated factor II (anti-FIIa) and anti-activated factor X (anti-FXa) activity, platelet adhesion, platelet count, platelet-induced thrombin generation time (PITT), bleeding time, antithrombin III, fibrinogen and several safety parameters. After single intravenous (i.v.) injections of IK-SSH (0.14, 0.33 and 0.66 mg/kg) aPTT, Heptest and PITT were strongly and dose-dependently prolonged. After ascending subcutaneous (s.c.) doses of IK-SSH (0.33, 0.66 and 1 mg/kg) aPTT, Heptest and PITT were prolonged in a dose-dependent manner. Repeat s.c. injections of 1 mg/kg IK-SSH for 5 days markedly prolonged aPTT, Heptest and PITT. No cumulative effects were observed. Anti-FIIa and anti-FXa activity were not or only slightly increased. Bleeding time, thrombin time and platelet adhesion were not significantly changed after i.v. and s.c. injections of IK-SSH. However, tissue factor pathway inhibitor (TFPI) concentration was markedly increased after each injection of IK-SSH and returned to the preinjection value 24 h later. IK-SSH prolongs aPTT, Heptest and PITT in a similar manner as other low molecular weight heparins but without significantly affecting thrombin time, FIIa and FXa activity. The release of TFPI may well be responsible for the prolongation of aPTT, Heptest and PITT. IK-SSH may be further developed as an antithrombotic agent.

  20. The effect of PEG molecular weights on the thermal stability and dissolution behaviors of griseofulvin-PEG crystalline inclusion complexes.

    Science.gov (United States)

    Yang, Xiaotong; Zhong, Zhi; Huang, Yanbin

    2016-07-11

    Co-crystals formed between small molecular drugs and hydrophilic co-formers have shown great potential to optimize the dissolution profiles of drug substances. So far most of the co-formers used are small molecules. However, linear polymers are also able to form drug-polymer crystalline inclusion complexes (ICs). In contrast to the small molecular co-formers, molecular weight of the polymer co-formers can be easily changed without disrupting the IC crystal structure, and hence represents an interesting approach to tune the IC properties. In this study, we investigated the effect of PEG molecular weights on the thermal stability and dissolution behavior of Gris-PEG ICs. It was found that the thermal stability of Gris-PEG IC crystals first increased with PEG molecular weight, and then reached a plateau value, while an optimized PEG molecular weight existed for the dissolution profile. The experimental results were explained by the formation of two types of crystal defects during the IC growth in PEG melt: the void defects and the grain boundary defects. This is the first study on the pharmaceutical profiles of drug-polymer crystalline inclusion complexes. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Association of Anthropometric and Bioelectrical Impedance Analysis Measures of Adiposity with High Molecular Weight Adiponectin Concentration.

    Science.gov (United States)

    Zeng, Wei-Fang; Li, Yan; Sheng, Chang-Sheng; Huang, Qi-Fang; Kang, Yuan-Yuan; Zhang, Lu; Wang, Shuai; Cheng, Yi-Bang; Li, Fei-Ka; Wang, Ji-Guang

    2016-01-01

    To investigate the relationship between adiposity measures and plasma concentration of high molecular weight (HMW) adiponectin. In a Chinese sample (n = 1081), we performed measurements of anthropometry and bioelectrical impedance analysis (BIA). We defined overweight and obesity as a body mass index between 24 and 27.4 kg/m² and ≥ 27.5 kg/m², respectively, and central obesity as a waist circumference ≥ 90 cm in men and ≥ 80 cm in women. Plasma HMW adiponectin concentration was measured by the ELISA method. Plasma HMW adiponectin concentration was significantly (P obesity (n = 60, 1.31 μg/mL and n = 82, 2.10 μg/mL, respectively) than normal weight subjects (n = 185, 2.07μg/mL and n = 368, 2.94 μg/mL, respectively) and in the presence of central obesity (n = 106, 1.28 μg/mL and n = 331, 2.12 μg/mL, respectively) than subjects with a normal waist circumference (n = 298, 1.74 μg/mL and n = 346, 2.74 μg/mL, respectively). In multiple regression analyses stratified for gender, adjusted for confounders and considered separately each of the adiposity measures, all adiposity measures were significantly (r -0.18 to -0.31, P obesity, such as waist-to-hip ratio, but not BIA measures, are independently associated with plasma adiponectin concentration.

  2. Epoxy resin synthesis using low molecular weight lignin separated from various lignocellulosic materials.

    Science.gov (United States)

    Asada, Chikako; Basnet, Sunita; Otsuka, Masaya; Sasaki, Chizuru; Nakamura, Yoshitoshi

    2015-03-01

    A low molecular weight lignin from various lignocellulosic materials was used for the synthesis of bio-based epoxy resins. The lignin extracted with methanol from steam-exploded samples (steaming time of 5 min at steam pressure of 3.5 MPa) from different biomasses (i.e., cedar, eucalyptus, and bamboo) were functionalized by the reaction with epichlorohydrin, catalyzed by a water-soluble phase transfer catalyst tetramethylammonium chloride, which was further reacted with 30 wt% aqueous NaOH for ring closure using methyl ethyl ketone as a solvent. The glycidylated products of the lignin with good yields were cured to epoxy polymer networks with bio-based curing agents i.e., lignin itself and a commercial curing agent TD2131. Relatively good thermal properties of the bio-based epoxy network was obtained and thermal decomposition temperature at 5% weight loss (Td5) of cedar-derived epoxy resin was higher than that derived from eucalyptus and bamboo. The bio-based resin satisfies the stability requirement of epoxy resin applicable for electric circuit boards. The methanol-insoluble residues were enzymatically hydrolyzed to produce glucose. This study indicated that the biomass-derived methanol-soluble lignin may be a promising candidate to be used as a substitute for petroleum-based epoxy resin derived from bisphenol A, while insoluble residues may be processed to give a bioethanol precursor i.e., glucose. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Low Molecular Weight Fucoidan Inhibits Tumor Angiogenesis through Downregulation of HIF-1/VEGF Signaling under Hypoxia

    Directory of Open Access Journals (Sweden)

    Meng-Chuan Chen

    2015-07-01

    Full Text Available Activation of hypoxia-induced hypoxia-inducible factors-1 (HIF-1 plays a critical role in promoting tumor angiogenesis, growth and metastasis. Low molecular weight fucoidan (LMWF is prepared from brown algae, and exhibits anticancer activity. However, whether LMWF attenuates hypoxia-induced angiogenesis in bladder cancer cells and the molecular mechanisms involved remain unclear. This is the first study to demonstrate that LMWF can inhibit hypoxia-stimulated H2O2 formation, HIF-1 accumulation and transcriptional activity vascular endothelial growth factor (VEGF secretion, and the migration and invasion in hypoxic human bladder cancer cells (T24 cells. LMWF also downregulated hypoxia-activated phosphorylation of PI3K/AKT/mTOR/p70S6K/4EBP-1 signaling in T24 cells. Blocking PI3K/AKT or mTOR activity strongly diminished hypoxia-induced HIF-1α expression and VEGF secretion in T24 cells, supporting the involvement of PI3K/AKT/mTOR in the induction of HIF-1α and VEGF. Additionally, LMWF significantly attenuated angiogenesis in vitro and in vivo evidenced by reduction of tube formation of hypoxic human umbilical vascular endothelial cells and blood capillary generation in the tumor. Similarly, administration of LMWF also inhibited the HIF-1α and VEGF expression in vivo, accompanied by a reduction of tumor growth. In summary, under hypoxia conditions, the antiangiogenic activity of LMWF in bladder cancer may be associated with suppressing HIF-1/VEGF-regulated signaling pathway.

  4. Purification of High Molecular Weight Genomic DNA from Powdery Mildew for Long-Read Sequencing.

    Science.gov (United States)

    Feehan, Joanna M; Scheibel, Katherine E; Bourras, Salim; Underwood, William; Keller, Beat; Somerville, Shauna C

    2017-03-31

    The powdery mildew fungi are a group of economically important fungal plant pathogens. Relatively little is known about the molecular biology and genetics of these pathogens, in part due to a lack of well-developed genetic and genomic resources. These organisms have large, repetitive genomes, which have made genome sequencing and assembly prohibitively difficult. Here, we describe methods for the collection, extraction, purification and quality control assessment of high molecular weight genomic DNA from one powdery mildew species, Golovinomyces cichoracearum. The protocol described includes mechanical disruption of spores followed by an optimized phenol/chloroform genomic DNA extraction. A typical yield was 7 µg DNA per 150 mg conidia. The genomic DNA that is isolated using this procedure is suitable for long-read sequencing (i.e., > 48.5 kbp). Quality control measures to ensure the size, yield, and purity of the genomic DNA are also described in this method. Sequencing of the genomic DNA of the quality described here will allow for the assembly and comparison of multiple powdery mildew genomes, which in turn will lead to a better understanding and improved control of this agricultural pathogen.

  5. Low molecular weight hyaluronan induces lymphangiogenesis through LYVE-1-mediated signaling pathways.

    Directory of Open Access Journals (Sweden)

    Man Wu

    Full Text Available Hyaluronan (HA, a large nonsulfated glycosaminogycan in the extracellular matrix, whose degraded fragments termed as low molecular weight hyaluronan (LMW-HA, has been reported as an important regulator of angiogenesis. However, little is known about the influence of LMW-HA on lymphangiogenesis. In this study, we try to explore the in vitro effects of LMW-HA on lymphangiogenesis and identify the underlying molecular mechanisms. Our results showed that LMW-HA stimulation significantly increased lymphatic endothelial cells (LECs proliferation, migration and tube formation. Further experiments demonstrated that LMW-HA altered actin cytoskeleton rearrangement and increased the formation of intense stress fibers, lamellipodia and filopodia. Mechanistically, LMW-HA stimulation resulted in rapid tyrosine phosphorylation of protein kinase C α/βII (PKCα/βII and extracellular-regulated kinase 1/2 (ERK1/2. Lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1, a homologue of CD44, is the main cell surface receptor for HA in LECs. Blocking the binding interaction of LMW-HA with LYVE-1 using neutralizing anti-LYVE-1 antibodies significantly inhibited LECs proliferation, migration, tube formation and signal transduction induced by LMW-HA, suggesting that LMW-HA may play a critical role in the processes required for lymphangiogenesis through interactions with its receptor LYVE-1 and triggering intracellular signal cascades.

  6. EFFECT OF MOLECULAR WEIGHT ON THE YIELD BEHAVIOUR OF EPY EPOXY COMPOUND

    Directory of Open Access Journals (Sweden)

    Magdalena Urbaniak

    2016-12-01

    Full Text Available A series of epoxy networks with molecular weight between crosslinks (Mc ranging from 117 to 508 g/mol were investigated by employing as DSC and DMA methods and compression testing over a broad range of test temperatures (from 20 to 120 °C and strain rates (from 0.0208 to 20.8 min–1. Mechanical characteristics vs. testing temperature and strain rate developed in relation to working conditions of EPY compound applied for machine foundation chocks as well as effect of crosslinking on glass transition temperature (Tg presented in this paper let to find out the effect of molecular architecture composed chiefly by Mc on the thermal and mechanical properties that govern yield behaviour of the material. The investigations carried out in a.m. ranges of testing temperatures and strain rates showed that whichever change of Mc is related to the change in crosslink density causing relative shift in the Tg of the compound. However, a sensitivity of the polymer material on changes in strain rate falls down with growth of testing temperature. Obtained results prove that yielding in EPY compound can be examined in categories of the Eyring’s plastic flow model in which yielding is described.

  7. Synthesis of Disentangled Ultra-High Molecular Weight Polyethylene: Influence of Reaction Medium on Material Properties

    Directory of Open Access Journals (Sweden)

    Giuseppe Forte

    2017-01-01

    Full Text Available The polymerization of ethylene to Ultra-High Molecular Weight Polyethylene (UHMWPE in certain reaction conditions allows synthesis of nascent powders with a considerably lower amount of entanglements: the material obtained is of great interest from both academic and industrial viewpoints. From an academic point of view, it is interesting to follow the evolution of the metastable melt state with the progressive entanglements formation. Industrially, it is valuable to have a solvent-free processing route for the production of high modulus, high strength tapes. Since the polymer synthesis is performed in the presence of a solvent, it is interesting to investigate the influence that the reaction medium can have on the catalyst activity, resultant molecular characteristics, and polymer morphology at the macroscopic as wells as microscopic level. In this paper, we present the effect that two typical polymerization solvents, toluene and heptane, and mixtures of them, have on the catalytic performance and on the polymer properties. The observations are that an unexpected increase of catalyst activity, accompanied by a significant improvement in mechanical properties, is found when using a carefully chosen mixture of solvents. A tentative explanation is given on the basis of the presented results.

  8. Therapeutic effects of high molecular weight hyaluronan injections for tendinopathy in a rat model.

    Science.gov (United States)

    Yoshida, Mamoru; Funasaki, Hiroki; Kubota, Makoto; Marumo, Keishi

    2015-01-01

    Tendinopathy is the most common tendon disorder. The etiology is still uncertain, and the disorder poses many therapeutic problems. In a few clinical studies, analgesic effects of high molecular weight hyaluronan (HMW HA) injections were observed, but the underlying mechanisms were not elucidated. In the present study, we analyzed the therapeutic effects of hyaluronan injections for tendinopathy in an animal model. We made the tendinopathy rat model using a rodent treadmill machine. Rats with tendinopathy were injected with HMW HA (HA group), normal saline (NS group), or nothing (control group) into the space between the patellar tendon and the fat pad bilaterally, or were injected with HMW HA into the right knees and with saline to the left knees (HA/NS group), 5 times every 4 days. To assess the pain-relieving effect of HA, the spontaneous locomotor activities at night (12 h) and weight bearing of hind paws were measured every day. Histological sections of the patellar tendon stained with hematoxylin-eosin or prepared by TdT-mediated dUTP nick end labeling were microscopically analyzed. The number of spontaneous locomotor activities in the HA group was significantly larger than those in NS or control groups, and in the HA group they recovered up to a healthy level. The percent weight distribution of the right hind paws was significantly increased along with the number of injections. On histologic examinations, the numbers of microtears, laminations, or apoptotic cells in the patellar tendons in the HA group were significantly lower than those in the NS or the control groups. The injections of HMW HA were effective for pain relief and for partial restoration of the patellar tendon in our tendinopathy rat model, and thus may become an effective therapeutic modality for the disease.

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

    Science.gov (United States)

    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

  10. Mechanistic investigation of Fe(III) oxide reduction by low molecular weight organic sulfur species

    Science.gov (United States)

    Eitel, Eryn M.; Taillefert, Martial

    2017-10-01

    Low molecular weight organic sulfur species, often referred to as thiols, are known to be ubiquitous in aquatic environments and represent important chemical reductants of Fe(III) oxides. Thiols are excellent electron shuttles used during dissimilatory iron reduction, and in this capacity could indirectly affect the redox state of sediments, release adsorbed contaminants via reductive dissolution, and influence the carbon cycle through alteration of bacterial respiration processes. Interestingly, the reduction of Fe(III) oxides by thiols has not been previously investigated in environmentally relevant conditions, likely due to analytical limitations associated with the detection of thiols and their oxidized products. In this study, a novel electrochemical method was developed to simultaneously determine thiol/disulfide pair concentrations in situ during the reduction of ferrihydrite in batch reactors. First order rate laws with respect to initial thiol concentration were confirmed for Fe(III) oxyhydroxide reduction by four common thiols: cysteine, homocysteine, cysteamine, and glutathione. Zero order was determined for both Fe(III) oxyhydroxide and proton concentration at circumneutral pH. A kinetic model detailing the molecular mechanism of the reaction was optimized with proposed intermediate surface structures. Although metal oxide overall reduction rate constants were inversely proportional to the complexity of the thiol structure, the extent of metal reduction increased with structure complexity, indicating that surface complexes play a significant role in the ability of these thiols to reduce iron. Taken together, these results demonstrate the importance of considering the molecular reaction mechanism at the iron oxide surface when investigating the potential for thiols to act as electron shuttles during dissimilatory iron reduction in natural environments.

  11. An innovative method for preparation of acid-free-water-soluble low-molecular-weight chitosan (AFWSLMWC).

    Science.gov (United States)

    Yue, Wu; Yao, Pingjia; Wei, Yuanan; Li, Shiqian; Lai, Fang; Liu, Xiongmin

    2008-06-01

    The ozone generated from compressed oxygen by a laboratory-scale corona discharge generator was used for the preparation of acid-free-water-soluble low-molecular-weight chitosan (AFWSLMWC). Factors affecting the percent yield of AFWSLMWC were studied in batch experiments. AFWSLMWC with a molecular weight of 4.3-13.1kDa was obtained. IR spectra demonstrated that the chemical structures of AFWSLMWC were not modified during the depolymerisation process. There was no significant change of the total degree of deacetylation (DD) of AFWSLMWC, compared with the initial chitosan. The method is promisingly suitable for scale-up manufacture of acid-free-water-soluble low-molecular-weight chitosan. Copyright © 2007 Elsevier Ltd. All rights reserved.

  12. Molecular weight and tacticity effect on morphological and mechanical properties of Ziegler–Natta catalyzed isotactic polypropylenes

    Directory of Open Access Journals (Sweden)

    Ismael Amer

    2015-01-01

    Full Text Available Abstract The morphological and mechanical properties of Ziegler–Natta catalyzed isotactic polypropylenes as influenced by the molecular weight and tacticity was investigated. Polypropylene samples were injection moulded into standard disks with a HAAKE MiniJet II injection moulder at 190 °C and 200 bar for morphological and mechanical tests. The morphological and mechanical properties of specimens were investigated by means of optical microscope (OM, scanning electron microscopy (SEM, microhardness (MH and dynamic mechanical analysis (DMA. The samples exhibited a typical α-modification spherulite structure of isotactic polypropylenes crystallized from the melt. It was found that the most important factor affecting the structure and properties of these polymers is the isotacticity content. A clear molecular weight effect was also found for samples with low molecular weights. The microhardness and storage modulus values increased as crystallinity did. Accordingly, isotacticity degree is considered as the main parameter affecting the crystallinity of samples.

  13. Effect of alkali lignins with different molecular weights from alkali pretreated rice straw hydrolyzate on enzymatic hydrolysis.

    Science.gov (United States)

    Li, Yun; Qi, Benkun; Luo, Jianquan; Wan, Yinhua

    2016-01-01

    This study investigated the effect of alkali lignins with different molecular weights on enzymatic hydrolysis of lignocellulose. Different alkali lignins fractions, which were obtained from cascade ultrafiltration, were added into the dilute acid pretreated (DAP) and alkali pretreated (AP) rice straws respectively during enzymatic hydrolysis. The results showed that the addition of alkali lignins enhanced the hydrolysis and the enhancement for hydrolysis increased with increasing molecular weights of alkali lignins, with maximum enhancement being 28.69% for DAP and 20.05% for AP, respectively. The enhancement was partly attributed to the improved cellulase activity, and filter paper activity increased by 18.03% when adding lignin with highest molecular weight. It was found that the enhancement of enzymatic hydrolysis was correlated with the adsorption affinity of cellulase on alkali lignins, and the difference in surface charge and hydrophobicity of alkali lignins were responsible for the difference in affinity between cellulase and lignins. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Practical Application of Aptamer-Based Biosensors in Detection of Low Molecular Weight Pollutants in Water Sources

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2018-02-01

    Full Text Available Water pollution has become one of the leading causes of human health problems. Low molecular weight pollutants, even at trace concentrations in water sources, have aroused global attention due to their toxicity after long-time exposure. There is an increased demand for appropriate methods to detect these pollutants in aquatic systems. Aptamers, single-stranded DNA or RNA, have high affinity and specificity to each of their target molecule, similar to antigen-antibody interaction. Aptamers can be selected using a method called Systematic Evolution of Ligands by EXponential enrichment (SELEX. Recent years we have witnessed great progress in developing aptamer selection and aptamer-based sensors for low molecular weight pollutants in water sources, such as tap water, seawater, lake water, river water, as well as wastewater and its effluents. This review provides an overview of aptamer-based methods as a novel approach for detecting low molecular weight pollutants in water sources.

  15. Quantum nonequilibrium equalities with absolute irreversibility

    Science.gov (United States)

    Funo, Ken; Murashita, Yûto; Ueda, Masahito

    2015-07-01

    We derive quantum nonequilibrium equalities in absolutely irreversible processes. Here by absolute irreversibility we mean that in the backward process the density matrix does not return to the subspace spanned by those eigenvectors that have nonzero weight in the initial density matrix. Since the initial state of a memory and the postmeasurement state of the system are usually restricted to a subspace, absolute irreversibility occurs during the measurement and feedback processes. An additional entropy produced in absolutely irreversible processes needs to be taken into account to derive nonequilibrium equalities. We discuss a model of a feedback control on a qubit system to illustrate the obtained equalities. By introducing N heat baths each composed of a qubit and letting them interact with the system, we show how the entropy reduction via feedback control can be converted into work. An explicit form of extractable work in the presence of absolute irreversibility is given.

  16. Effects of molecular weight of hyaluronic acid on its viscosity and enzymatic activities of lysozyme and peroxidase.

    Science.gov (United States)

    Kim, Jihoon; Chang, Ji-Youn; Kim, Yoon-Young; Kim, Moon-Jong; Kho, Hong-Seop

    2018-02-14

    To investigate the effects of the molecular weight of hyaluronic acid on its viscosity and enzymatic activities of lysozyme and peroxidase in solution and on the hydroxyapatite surface. Hyaluronic acids of four different molecular weights (10 kDa, 100 kDa, 1 MDa, and 2 MDa), hen egg-white lysozyme, bovine lactoperoxidase, and human whole saliva were used. Viscosity values of hyaluronic acids were measured using a cone-and-plate viscometer at six different concentrations (0.1-5.0 mg/mL). Enzymatic activities of lysozyme and peroxidase were examined by hydrolysis of fluorescein-labeled Micrococcus lysodeikticus and oxidation of fluorogenic 2',7'-dichlorofluorescein to fluorescing 2',7'-dichlorofluorescein, respectively. In solution assays, only 2 MDa-hyaluronic acid significantly inhibited lysozyme activities in saliva. In surface assays, hyaluronic acids inhibited lysozyme and peroxidase activities; the inhibitory activities were more apparent with high-molecular-weight ones in saliva than in purified enzymes. The 100 kDa-hyaluronic acid at 5.0 mg/mL, 1 MDa-one at 0.5 mg/mL, and 2 MDa-one at 0.2 mg/mL showed viscosity values similar to those of human whole saliva at a shear rate range required for normal oral functions. The differences among the influences of the three conditions on the enzymatic activities were not statistically significant. High-molecular-weight hyaluronic acids at low concentration and low-molecular-weight ones at high concentration showed viscosity values similar to those of human whole saliva. Inhibitory effects of hyaluronic acids on lysozyme and peroxidase activities were more significant with high-molecular-weight ones on the surface and in saliva compared with in solution and on purified enzymes. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Poly (N-isopropylacrylamide microgel-based etalons and etalon arrays for determining the molecular weight of polymers in solution

    Directory of Open Access Journals (Sweden)

    Molla R. Islam

    2013-11-01

    Full Text Available Positively and/or negatively charged poly (N-isopropylacrylamide-based microgels were deposited on a single substrate and isolated regions of Au overlayers were deposited on top of the microgels. Each spatially isolated Au overlayer region had a different thickness to make an etalon array. We found that areas with a thin Au overlayer (5 nm responded to a range of polymer molecular weights (MW, while areas with a thick overlayer (35 nm can only respond to low molecular weight polyelectrolytes. By comparing the optical responses of the device's individual array elements, a good approximation of the polyelectrolyte MW in solution can be made.

  18. Preparation of Low Allergenic Protein Concentrated Natural Rubber Latex Using Suitable Low Molecular Weight Cellulose Derivatives Induced by Gamma Irradiation

    International Nuclear Information System (INIS)

    Siri-Upathum, Chyagrit; Boonyawat, Jariya

    2007-08-01

    Full text: Low molecular weight carboxy methyl cellulose (CMC), hydroxyl ethyl cellulose (HEC), hydroxyl propyl cellulose (HPC) and methyl cellulose (MC) prepared by radiation-induced degradation were added into diluted natural concentrated latex prior to centrifuge for a purpose of reducing allergenic rubber protein in the latex. Optimum molecular weight (Mv) of CMC and HEC for such a purpose was found to be 17-18 kDa which decreased allergenic rubber protein (14-94 kDa) to an undetectable amount as determined by SDS PAGE method

  19. Relationship of amino acid composition and molecular weight of antifreeze glycopeptides to non-colligative freezing point depression.

    Science.gov (United States)

    Schrag, J D; O'Grady, S M; DeVries, A L

    1982-08-06

    Many polar fishes synthesize a group of eight glycopeptides that exhibit a non-colligative lowering of the freezing point of water. These glycopeptides range in molecular weight between 2600 and 33 700. The largest glycopeptides [1-5] lower the freezing point more than the small ones on a weight basis and contain only two amino acids, alanine and threonine, with the disaccharide galactose-N-acetyl-galactosamine attached to threonine. The small glycopeptides, 6, 7, and 8, also lower the freezing point and contain proline, which periodically substitutes for alanine. Glycopeptides with similar antifreeze properties isolated from the saffron cod and the Atlantic tomcod contain an additional amino acid, arginine, which substitutes for threonine in glycopeptide 6. In this study we address the question of whether differences in amino acid composition or molecular weight between large and small glycopeptides are responsible for the reduced freezing point depressing capability of the low molecular weight glycopeptides. The results indicate that the degree of amino acid substitutions that occur in glycopeptides 6-8 do not have a significant effect on the unusual freezing point lowering and that the observed decrease in freezing point depression with smaller glycopeptides can be accounted for on the basis of molecular weight.

  20. NGS Absolute Gravity Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NGS Absolute Gravity data (78 stations) was received in July 1993. Principal gravity parameters include Gravity Value, Uncertainty, and Vertical Gradient. The...

  1. Low molecular weight components in an aquatic humic substance as characterized by membrane dialysis and orbitrap mass spectrometry.

    Science.gov (United States)

    Remucal, Christina K; Cory, Rose M; Sander, Michael; McNeill, Kristopher

    2012-09-04

    Suwannee River fulvic acid (SRFA) was dialyzed through a 100-500 molecular weight cutoff dialysis membrane, and the dialysate and retentate were analyzed by UV-visible absorption and high-resolution Orbitrap mass spectrometry (MS). A significant fraction (36% based on dissolved organic carbon) of SRFA passed through the dialysis membrane. The fraction of SRFA in the dialysate had a different UV-visible absorption spectrum and was enriched in low molecular weight molecules with a more aliphatic composition relative to the initial SRFA solution. Comparison of the SRFA spectra collected by Orbitrap MS and Fourier transform ion cyclotron resonance MS (FT-ICR MS) demonstrated that the mass accuracy of the Orbitrap MS is sufficient for determination of unique molecular formulas of compounds with masses masses detected by Orbitrap MS were found in the 100-200 Da mass range. Many of these low molecular masses corresponded to molecular formulas of previously identified compounds in organic matter, lignin, and plants, and the use of the standard addition method provided an upper concentration estimate of selected target compounds in SRFA. Collectively, these results provide evidence that SRFA contains low molecular weight components that are present individually or in loosely bound assemblies.

  2. Decoherence at absolute zero

    OpenAIRE

    Sinha, Supurna

    2005-01-01

    We present an analytical study of the loss of quantum coherence at absolute zero. Our model consists of a harmonic oscillator coupled to an environment of harmonic oscillators at absolute zero. We find that for an Ohmic bath, the offdiagonal elements of the density matrix in the position representation decay as a power law in time at late times. This slow loss of coherence in the quantum domain is qualitatively different from the exponential decay observed in studies of high temperature envir...

  3. Ingestion of High Molecular Weight Carbohydrate Enhances Subsequent Repeated Maximal Power: A Randomized Controlled Trial.

    Science.gov (United States)

    Oliver, Jonathan M; Almada, Anthony L; Van Eck, Leighsa E; Shah, Meena; Mitchell, Joel B; Jones, Margaret T; Jagim, Andrew R; Rowlands, David S

    2016-01-01

    Athletes in sports demanding repeat maximal work outputs frequently train concurrently utilizing sequential bouts of intense endurance and resistance training sessions. On a daily basis, maximal work within subsequent bouts may be limited by muscle glycogen availability. Recently, the ingestion of a unique high molecular weight (HMW) carbohydrate was found to increase glycogen re-synthesis rate and enhance work output during subsequent endurance exercise, relative to low molecular weight (LMW) carbohydrate ingestion. The effect of the HMW carbohydrate, however, on the performance of intense resistance exercise following prolonged-intense endurance training is unknown. Sixteen resistance trained men (23±3 years; 176.7±9.8 cm; 88.2±8.6 kg) participated in a double-blind, placebo-controlled, randomized 3-way crossover design comprising a muscle-glycogen depleting cycling exercise followed by ingestion of placebo (PLA), or 1.2 g•kg•bw-1 of LMW or HMW carbohydrate solution (10%) with blood sampling for 2-h post-ingestion. Thereafter, participants performed 5 sets of 10 maximal explosive repetitions of back squat (75% of 1RM). Compared to PLA, ingestion of HMW (4.9%, 90%CI 3.8%, 5.9%) and LMW (1.9%, 90%CI 0.8%, 3.0%) carbohydrate solutions substantially increased power output during resistance exercise, with the 3.1% (90% CI 4.3, 2.0%) almost certain additional gain in power after HMW-LMW ingestion attributed to higher movement velocity after force kinematic analysis (HMW-LMW 2.5%, 90%CI 1.4, 3.7%). Both carbohydrate solutions increased post-exercise plasma glucose, glucoregulatory and gut hormones compared to PLA, but differences between carbohydrates were unclear; thus, the underlying mechanism remains to be elucidated. Ingestion of a HMW carbohydrate following prolonged intense endurance exercise provides superior benefits to movement velocity and power output during subsequent repeated maximal explosive resistance exercise. This study was registered with

  4. High molecular weight barley β-glucan alters gut microbiota toward reduced cardiovascular disease risk

    Directory of Open Access Journals (Sweden)

    Yanan eWang

    2016-02-01

    Full Text Available The physiological cholesterol-lowering benefits of β-glucan have been well documented, however, whether modulation of gut microbiota by β-glucan is associated with these physiological effects remains unknown. The objectives of this study were therefore to determine the impact of β-glucan on the composition of gut microbiota in mildly hypercholesterolemic individuals and to identify if the altered microbiota are associated with bioactivity of β-glucan in improving risk factors of cardiovascular disease (CVD. Using a randomized, controlled crossover study design, individuals received for 5-week either a treatment breakfast containing 3g high molecular weight (HMW, 3g low molecular weight (LMW, 5g LMW barley β-glucan or wheat and rice (WR. The American Heart Association (AHA diet served as the background diet for all treatment groups. Phases were separated by 4-week washout periods. Fecal samples were collected at the end of each intervention phase and subjected to Illumina sequencing of 16S rRNA genes. Results revealed that at the phylum level, supplementation of 3g/d HMW β-glucan increased Bacteroidetes and decreased Firmicutes abundances compared to control (P < 0.001. At the genus level, consumption of 3g/d HMW β-glucan increased Bacteroides (P < 0.003, tended to increase Prevotella (P < 0.1 but decreased Dorea (P < 0.1, whereas diets containing 5g LMW β-glucan and 3g LMW β-glucan failed to alter the gut microbiota composition. Bacteroides, Prevotella, and Dorea composition correlated (P < 0.05 with shifts of CVD risk factors, including body mass index, waist circumference, blood pressure, as well as triglyceride levels. Our data suggest that consumption of HMW β-glucan favourably alters the composition of the gut microbiota and this altered microbiota profile associates with a reduction of CVD risk markers. Together, our study suggests that β-glucan induced shifts in gut microbiota in a MW-dependent manner and that might be one of

  5. Ingestion of High Molecular Weight Carbohydrate Enhances Subsequent Repeated Maximal Power: A Randomized Controlled Trial.

    Directory of Open Access Journals (Sweden)

    Jonathan M Oliver

    Full Text Available Athletes in sports demanding repeat maximal work outputs frequently train concurrently utilizing sequential bouts of intense endurance and resistance training sessions. On a daily basis, maximal work within subsequent bouts may be limited by muscle glycogen availability. Recently, the ingestion of a unique high molecular weight (HMW carbohydrate was found to increase glycogen re-synthesis rate and enhance work output during subsequent endurance exercise, relative to low molecular weight (LMW carbohydrate ingestion. The effect of the HMW carbohydrate, however, on the performance of intense resistance exercise following prolonged-intense endurance training is unknown. Sixteen resistance trained men (23±3 years; 176.7±9.8 cm; 88.2±8.6 kg participated in a double-blind, placebo-controlled, randomized 3-way crossover design comprising a muscle-glycogen depleting cycling exercise followed by ingestion of placebo (PLA, or 1.2 g•kg•bw-1 of LMW or HMW carbohydrate solution (10% with blood sampling for 2-h post-ingestion. Thereafter, participants performed 5 sets of 10 maximal explosive repetitions of back squat (75% of 1RM. Compared to PLA, ingestion of HMW (4.9%, 90%CI 3.8%, 5.9% and LMW (1.9%, 90%CI 0.8%, 3.0% carbohydrate solutions substantially increased power output during resistance exercise, with the 3.1% (90% CI 4.3, 2.0% almost certain additional gain in power after HMW-LMW ingestion attributed to higher movement velocity after force kinematic analysis (HMW-LMW 2.5%, 90%CI 1.4, 3.7%. Both carbohydrate solutions increased post-exercise plasma glucose, glucoregulatory and gut hormones compared to PLA, but differences between carbohydrates were unclear; thus, the underlying mechanism remains to be elucidated. Ingestion of a HMW carbohydrate following prolonged intense endurance exercise provides superior benefits to movement velocity and power output during subsequent repeated maximal explosive resistance exercise. This study was registered

  6. Plasticization of poly(lactic acid) using different molecular weight of Poly(ethylene glycol)

    Science.gov (United States)

    Septevani, Athanasia Amanda; Bhakri, Samsul

    2017-11-01

    Poly (lactic acid) (PLA) has been known as an excellent candidate for developing the future bioplastic due to its biodegradability and competitive price. However, inherent brittleness and low thermal stability of PLA have limited its applications. Considerable studies have been developed to improve the flexibility of PLA, in which blending PLA with various plasticizers has been identified as a cost-effective way to lower glass-transition temperature (Tg) and thus improve its elongation property. In this study, PLA was modified by incorporating poly(ethylene glycol) as a plasticizer with different molecular weights (M¯w 400, 1000, and 6000, called respectively as PEG 400, PEG 1000, and PEG 6000) via a solvent-casting blend method. FTIR was used for analyzing the chemical interaction while TGA and DSC measured the thermal behavior of PLA/PEG. The results indicated that the addition of lower M¯w (PEG 400 and PEG 1000) could reduce the Tg due to the enhancement of chain mobility of PLA with PEG and so driving into a more amorphous states resulted reduction of melting temperature (Tm) compared to the neat PLA. Further, at a higher M¯w of PEG 6000, the longer chain of ethylene glycol, in contrast, resulted a gradual increase in the Tg as well as Tm where the value went back to the point of neat PLA compared to the other lower molecular weight of PLA. This was due to the decrease in polymer miscibility with the increasing of M¯w. In terms of thermal stability, the addition of PEG exhibited two step degradation behavior while the neat PLA only possessed single step degradation. The presence of PEG could act as a protective barrier layer that could hinder the permeability of the volatile compound and product during decomposition reaction and thus could eventually delay and slower the degradation process. It was observed that the addition of PEG at higher M¯w (PEG1000 and PEG 6000) exhibited a higher second degradation temperature up to 380 °C.

  7. Low molecular weight heparin for prevention of venous thromboembolism in patients with lower-leg immobilization.

    Science.gov (United States)

    Testroote, Mark; Stigter, Willem A H; Janssen, Loes; Janzing, Heinrich M J

    2014-04-25

    Immobilization of the lower leg is associated with venous thromboembolism (VTE). Low molecular weight heparin (LMWH) is an anticoagulant treatment which might be used in adult patients with lower-leg immobilization to prevent deep venous thrombosis (DVT) and its complications. This is an update of the review first published in 2008. To assess the effectiveness of low molecular weight heparin for the prevention of venous thromboembolism in patients with lower-leg immobilization in an ambulant setting. For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched June 2013) and CENTRAL (2013, Issue 5). Randomized controlled trials (RCTs) and controlled clinical trials (CCTs) that described thromboprophylaxis by means of LMWH compared with no prophylaxis or placebo in adult patients with lower-leg immobilization. Immobilization was by means of a plaster cast or brace. Two authors independently assessed trial quality and extracted data. The review authors contacted the trial authors for additional information if required. Statistical analysis was carried out using Review Manager (RevMan 5). We included six RCTs fulfilling the above criteria with a total of 1490 patients. We found an incidence of VTE ranging from 4.3% to 40% in patients who had a leg injury that had been immobilized in a plaster cast or a brace for at least one week and who received no prophylaxis, or placebo. This number was significantly lower in patients who received daily subcutaneous injections of LMWH during immobilization (event rates ranging from 0% to 37%; odds ratio (OR) 0.49; fixed 95% confidence interval (CI) 0.34 to 0.72; with minimal evidence of heterogeneity with an I(2) of 20%, P = 0. 29). Comparable results were seen in the following subcategories: operated patients, conservatively treated patients, patients with fractures, patients with soft-tissue injuries, patients with proximal thrombosis, patients with

  8. The antioxidative and antilipidemic effects of different molecular weight chitosans in metabolic syndrome model rats.

    Science.gov (United States)

    Anraku, Makoto; Michihara, Akihiro; Yasufuku, Taira; Akasaki, Kenji; Tsuchiya, Daiju; Nishio, Hiroaki; Maruyama, Toru; Otagiri, Masaki; Maezaki, Yuji; Kondo, Yuko; Tomida, Hisao

    2010-01-01

    The effect of high and low molecular weight chitosans (HMC; 1000 kDa, LMC; 30 kDa) on oxidative stress and hypercholesterolemia was investigated using male 6-week-old Wistar Kyoto rats as a normal model (Normal-rats) and spontaneously hypertensive rat/ND mcr-cp (SHP/ND) as a metabolic syndrome model (MS-rats), respectively. In Normal-rats, the ingestion of both chitosans over a 4 week period resulted in a significant decrease in total body weight (BW), glucose (Gl), triglyceride (TG), low density lipoprotein (LDL) and serum creatinine (Cre) levels. The ingestion of both chitosans also resulted in a lowered ratio of oxidized to reduced albumin and an increase in total plasma antioxidant activity. In addition to similar results in Normal-rats, the ingestion of only HMC over a 4 week period resulted in a significant decrease in total cholesterol levels in MS-rats. Further, the ingestion of LMC resulted in a significantly higher antioxidant activity than was observed for HMC in both rat models. In in vitro studies, LMC caused a significantly higher reduction in the levels of two stable radicals, compared to HMC, and the effect was both dose- and time-dependent. The findings also show that LDL showed strong binding in the case of HMC. These results suggest that LMC has a high antioxidant activity as well as antilipidemic effects, while HMC results in a significant reduction in the levels of pro-oxidants such as LDL in the gastrointestinal tract, thereby inhibiting the subsequent development of oxidative stress in the systemic circulation in metabolic model rats.

  9. Molecular biomarkers for weight control in obese individuals subjected to a multi-phase dietary intervention

    DEFF Research Database (Denmark)

    Bolton, Jennifer L; Montastier, Emilie; Carayol, Jérôme

    2017-01-01

    Context: While calorie restriction has proven beneficial for weight loss, long-term weight control is variable between individuals. Objective: To identify biomarkers of successful weight control during a dietary intervention (DI). Design, Setting, and Participants: Adipose tissue (AT) transcripto......-controllers. Interestingly, ASPN is a TGFβ1 inhibitor. Conclusions: We found circulating biomarkers associated with weight control, which could influence weight management strategies, and genes that may be prognostic for successful weight control.......Context: While calorie restriction has proven beneficial for weight loss, long-term weight control is variable between individuals. Objective: To identify biomarkers of successful weight control during a dietary intervention (DI). Design, Setting, and Participants: Adipose tissue (AT......) transcriptomes were compared between 21 obese individuals that either maintained weight loss or regained weight during the DI. Results were validated on 310 individuals from the same study using RT-qPCR, and protein levels of potential circulating biomarkers measured by ELISA. Intervention: Individuals underwent...

  10. Start-Up and Transient Flow Effects From the Molecular Weight Distribution

    Science.gov (United States)

    Borg, Tommi; Pääkkönen, Esko J.

    2008-07-01

    Start-up and transient shear-stress flows are modeled here using the recently generated constitutive model for linear viscoelasticity of polymers. The relation derived from control theory and the melt calibration procedure has been developed between the relaxation modulus, dynamic viscosity, and molecular-weight distribution (MWD). This study extends the start-up, and transient effects of linear viscoelasticity on stress and viscosity from the novel viewpoint of the classical Boltzmann superposition principle. The shear viscosity measurements of well-characterized classical low-density polyethylene (LDPE IUPAC A) with a known MWD were used to obtain time-dependent stress and viscosity transitions. The developed formulas model the start-up situation with an overshoot effect and shear-stress growth coefficient. Simulations were performed for relaxation modulus measurements at different shear histories defined by the effective viscosity. As an example of practical application, injection molding for producing a cellular-phone cover were modeled to obtain the pressure loss and orientation level for every element in finite element models, which predicted the shrinking and warping of the end products.

  11. Low Molecular Weight Chitosan-Coated PLGA Nanoparticles for Pulmonary Delivery of Tobramycin for Cystic Fibrosis.

    Science.gov (United States)

    Al-Nemrawi, Nusaiba K; Alshraiedeh, Nid''A H; Zayed, Aref L; Altaani, Bashar M

    2018-03-08

    (1) Background: Poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) loaded with Tobramycin were prepared using a solvent-evaporation method. (2) Methods: The NPs were coated with low molecular weight chitosan (LMWC) to enhance the mucoadhesiveness of PLGA-NPs. The following w / w ratios of tobramycin to LMWC were prepared: control (0:0.50), F₀ (1:0.25), F₀.₅ (1:0.5), and F₁ (1:1). (3) Results: The results showed that the size of the particles increased from 220.7 nm to 575.77 nm as the concentration of LMWC used in the formulation increased. The surface charge was also affected by the amount of LMWC, where uncoated-PLGA nanoparticles had negative charges (-2.8 mV), while coated-PLGA NPs had positive charges (+33.47 to +50.13 mV). SEM confirmed the size and the spherical homogeneous morphology of the NPs. Coating the NPs with LMWC enhanced the mucoadhesive properties of the NPs and sustained the tobramycin release over two days. Finally, all NPs had antimicrobial activity that increased as the amount of LMWC increased. (4) Conclusion: In conclusion, the formulation of mucoadhesive, controlled-release, tobramycin-LMWC-PLGA nanoparticles for the treatment of P. aeruginosa in cystic fibrosis patients is possible, and their properties could be controlled by controlling the concentration of LMWC.

  12. Heparanase and Syndecan-4 Are Involved in Low Molecular Weight Fucoidan-Induced Angiogenesis

    Directory of Open Access Journals (Sweden)

    Oualid Haddad

    2015-10-01

    Full Text Available Induction of angiogenesis is a potential treatment for chronic ischemia. Low molecular weight fucoidan (LMWF, the sulfated polysaccharide from brown seaweeds, has been shown to promote revascularization in a rat limb ischemia, increasing angiogenesis in vivo. We investigated the potential role of two heparan sulfate (HS metabolism enzymes, exostosin-2 (EXT2 and heparanase (HPSE, and of two HS-membrane proteoglycans, syndecan-1 and -4 (SDC-1 and SDC-4, in LMWF induced angiogenesis. Our results showed that LMWF increases human vascular endothelial cell (HUVEC migration and angiogenesis in vitro. We report that the expression and activity of the HS-degrading HPSE was increased after LMWF treatment. The phenotypic tests of LMWF-treated and EXT2- or HPSE-siRNA-transfected cells indicated that EXT2 or HPSE expression significantly affect the proangiogenic potential of LMWF. In addition, LMWF increased SDC-1, but decreased SDC-4 expressions. The effect of LMWF depends on SDC-4 expression. Silencing EXT2 or HPSE leads to an increased expression of SDC-4, providing the evidence that EXT2 and HPSE regulate the SDC-4 expression. Altogether, these data indicate that EXT2, HPSE, and SDC-4 are involved in the proangiogenic effects of LMWF, suggesting that the HS metabolism changes linked to LMWF-induced angiogenesis offer the opportunity for new therapeutic strategies of ischemic diseases.

  13. Evaluation of low-molecular-weight heparin for the prevention of equine laminitis after colic surgery.

    Science.gov (United States)

    de la Rebière de Pouyade, Geoffroy; Grulke, Sigrid; Detilleux, Johann; Salciccia, Alexandra; Verwilghen, Denis R; Caudron, Isabelle; Gangl, Monika; Serteyn, Didier D A

    2009-02-01

    The aim of this study is to describe the prevalence of postoperative laminitis in colic cases and to determine if low-molecular-weight heparin (LMWH) is effective in preventing this complication. Retrospective clinical study. Client-owned horses. Interventions- SC administration of enoxaparin during the postoperative period. Medical records of 360 horses undergoing surgery for colic and surviving at least 3 days were evaluated. Fifty-six horses admitted before 1995 did not receive LMWH (control group) and 304 admitted after 1995 received LMWH as a prophylaxis for laminitis (treatment group). Three grades of severity were defined for laminitis. Prevalence and severity of laminitis were compared between the 2 groups. Several parameters recorded on admission (sex, age, breed, site and nature of the disease, heart rate, PCV, gravity score, and shock score) and the administration of LMWH were tested as risk factors in the development of laminitis in a logistic regression procedure. Prevalence and grade of laminitis were significantly lower in the treatment group. Only the absence of LMWH was recognized as a significant risk factor in the logistic regression model. The administration of LMWH appears to be effective in the prophylaxis of laminitis following colic surgery and may be useful in the postoperative management of these horses.

  14. Roles of Low Molecular Weight Amide on Crystallization Behavior of Poly (L-lactic acid)

    Science.gov (United States)

    Dong, Xia; Xing, Qian; Zhang, Xiuqin; Wang, Dujin

    2012-02-01

    Organic nucleating agents play an important role in enhancing the crystallization rate of polymers. The aim of this study is to investigate the effect of low molecular weight aliphatic amides on the crystallization behavior and mechanism of poly (L-lactic acid) (PLLA). The crystallization rate of PLLA during non-isothermal crystallization and isothermal crystallization has been significantly improved with the addition of N, N'-ethylenebis (12-hydroxystearamide) (EBH) and/or N, N'-ethylenebisstearamide (EBSA), and EBH exhibits stronger nucleating ability. Time-resolved FTIR spectra illustrate the chain conformational changes and the crystallization kinetics during isothermal crystallization of PLLA mixtures and pure PLLA, especially in the early stages. The formation of interchain conformational-ordered structure and intrachain 103 helix structure for amide-doped PLLA precedes that of pure PLLA, suggesting a stimulatory nucleating effect of EBH and EBSA. In the case of PLLA/EBH, the interchain interactions of -(COC+CH3) and -CH3 groups are faster than the -(CH3+CC) intrachain interactions, while the interchain interactions and the intrachain 103 helix formation are nearly synchronous for PLLA/EBSA, indicating that EBH has an improved effect on the nucleating ability and crystallization kinetics of PLLA, compared to EBSA. The possible mechanism has been discussed, which may be attributed to the hydrogen bond interaction between hydroxyl groups in EBH and the carbonyl groups in PLLA.

  15. Influences of poly (vinyl alcohol molecular weight and carbon nanotubes on radiation crosslinking shape memory polymers

    Directory of Open Access Journals (Sweden)

    Aamer A.M. Alfayyadh

    2017-06-01

    Full Text Available Polyvinyl alcohol (PVA of two molecular weights was used to prepare shape memory polymers based on chemical-crosslinking by glutaraldehyde. The chemical-crosslinking was done in the presence of 2-carboxyethyl acrylate oligomers (CEA and nano-filler [multi-wall carbon nanotubes (MWCNT and functionalized carbon nanotubes (MWCNT-NH2] followed by radiation-induced crosslinking. The analysis of the material revealed an increase in the gel fraction and a significant reduction in swelling of the nanocomposite material that was crosslinked with both glutaraldehyde and ionizing radiation. The radiation crosslinked nanocomposites demonstrated approximately a 90% gelation over a range of 50–300 kGy irradiation doses. The scanning electron microscopy (SEM analysis showed a homogeneous distribution of nanocomposites in the composite matrix. The thermal properties of radiation crosslinked (PVA/CEA and (PVA-CEA-nano-fillers were investigated by a thermogravimetric analysis (TGA. The mechanical properties were examined via dynamic mechanical analysis (DMA which showed significant variation because of the addition of nanocomposites. This radiation crosslinked materials show good shape memory behavior that may be useful in many applications based on the range of temperatures at which Tan δ appears.

  16. Circular dichroism studies of low molecular weight hydrogelators: The use of SRCD and addressing practical issues.

    Science.gov (United States)

    Sitsanidis, Efstratios D; Piras, Carmen C; Alexander, Bruce D; Siligardi, Giuliano; Jávorfi, Tamás; Hall, Andrew J; Edwards, Alison A

    2018-04-12

    Circular dichroism (CD) spectroscopy has been used extensively for the investigation of the conformation and configuration of chiral molecules, but its use for evaluating the mode of self-assembly in soft materials has been limited. Herein, we report a protocol for the study of such materials by electronic CD spectroscopy using commercial/benchtop instruments and synchrotron radiation (SR) using the B23 beamline available at Diamond Light Source. The use of the B23 beamtime for SRCD was advantageous because of the unique enhanced spatial resolution achieved because of its highly collimated and small beamlight cross section (ca. 250 μm) and higher photon flux in the far UV region (175-250 nm) enhancing the signal-to-noise ratio relative to benchtop CD instruments. A set of low molecular weight (LMW) hydrogelators, comprising two Fmoc-protected enantiomeric monosaccharides and one Fmoc dipeptide (Fmoc-FF), were studied. The research focused on the optimization of sample preparation and handling, which then enabled the characterization of sample conformational homogeneity and thermal stability. CD spectroscopy, in combination with other spectroscopic techniques and microscopy, will allow a better insight into the self-assembly of chiral building blocks into higher order structural architectures. © 2018 Wiley Periodicals, Inc.

  17. Macroradical reaction in ultra-high molecular weight polyethylene in the presence of vitamin E

    Energy Technology Data Exchange (ETDEWEB)

    Jahan, M.S., E-mail: mjahan@memphis.ed [Department of Physics, Biomaterials Research Laboratory, University of Memphis, 216 Manning Hall, Memphis, TN 38152 (United States); Walters, B.M. [Department of Physics, Biomaterials Research Laboratory, University of Memphis, 216 Manning Hall, Memphis, TN 38152 (United States)

    2011-02-15

    Free radical measurements in compression molded ultra-high molecular weight polyethylene (UHMWPE), which contained vitamin E ({alpha}-tocopherol ({alpha}-T)), was performed using electron spin resonance (ESR) technique in air at room temperature following gamma irradiation (25-32 kGy) in N{sub 2}. The vitamin E was incorporated into one set of samples by blending UHMWPE resin with vitamin E (1 and 10 wt%), then compression molded into a solid and then irradiated. Another set of samples had vitamin E incorporated into them by diffusing vitamin E at 100 {sup o}C for 2 h after irradiation. Compared to a control (with no vitamin E), the vitamin E-containing UHMWPE ({alpha}-TPE) samples suffered a partial loss of PE radicals, but this loss only occurred during or immediately after irradiation (before exposure to air). Subsequently, when all blended samples were exposed to air, the remaining radicals in each sample decayed to the well-known OIR, R1 (-{sup {center_dot}C}H-[CH=CH-]{sub m}-) and R2 ({sup {center_dot}O}CH-[CH=CH-]{sub m}-) radicals. However, because of the initial loss or partial quenching, {alpha}-TPE produced a lower concentration of OIR (measured over a four-year period), but no difference was found between 1% and 10% {alpha}-TPEs. In the diffused {alpha}-TPE, similar OIR was also found when tested after four months of post-treatment exposure to air.

  18. Effect of consolidation on adhesive and abrasive wear of ultra high molecular weight polyethylene.

    Science.gov (United States)

    Gul, Rizwan M; McGarry, Frederick J; Bragdon, Charles R; Muratoglu, Orhun K; Harris, William H

    2003-08-01

    Total hip replacement (THR) is widely performed to recover hip joint functions lost by trauma or disease and to relieve pain. The major cause of failure in THR is the wear of the ultra high molecular weight polyethylene (UHMWPE) component. The dominant wear mechanism in THR occurs through adhesion and abrasion. While poor consolidation of UHMWPE is known to increase the incidence of a different damage mode, delamination, which is the dominant wear mechanism in tibial inserts but uncommon in THR, the effect of consolidation on adhesive and abrasive wear of UHMWPE is not clear. In this study UHMWPE resin was subjected to hot isostatic pressing under a pressure of 138MPa at different temperatures (210 degrees C, 250 degrees C, and 300 degrees C) to achieve varying degrees of consolidation. The extent of consolidation was determined by optical microscopy using thin sections, and by scanning electron microscopy using cryofractured and solvent etched specimens. Wear behavior of the samples with varying degree of consolidation was determined using a bi-directional pin-on-disc machine simulating conditions in a hip joint. Increasing the processing temperature decreased the incidence of fusion defects and particle boundaries reflecting the powder flakes of the virgin resin, improving the consolidation. However, the bi-directional pin-on-disc wear rate did not change with the processing temperature, indicating that adhesive and abrasive wear is independent of the extent of consolidation in the range of parameters studied here.

  19. Field test of high molecular weight alcohol flushing for subsurface nonaqueous phase liquid remediation

    Science.gov (United States)

    Falta, Ronald W.; Lee, Cindy M.; Brame, Scott E.; Roeder, Eberhard; Coates, John T.; Wright, Charles; Wood, A. Lynn; Enfield, Carl G.

    1999-07-01

    A pilot scale field test of non-aqueous phase liquid (NAPL) removal using high molecular weight alcohols was conducted at Operable Unit 1, Hill Air Force Base, Utah. Petroleum hydrocarbons and spent solvents were disposed of in chemical disposal pits at this site, and these materials are now present in the subsurface in the form of a light non-aqueous phase liquid (LNAPL). This LNAPL is a complex mixture of aromatic and aliphatic hydrocarbons, chlorinated solvents, and other compounds. The field experiment was performed in a 5 m by 3 m confined test cell, formed by driving interlocking sheet pile walls through the contaminated zone into an underlying clay. The test involved the injection and extraction of about four pore volumes (1 pore volume=7000 L) of a mixture of 80% tert-butanol and 15% n-hexanol. The contaminants were removed by a combination of NAPL mobilization and enhanced dissolution, and the results of postflood soil coring indicate better than 90% removal of the more soluble contaminants (trichloroethane, toluene, ethylbenzene, xylenes, trimethylbenzene, naphthalene) and 70-80% removal of less soluble compounds (decane and undecane). The results of preflood and postflood NAPL partitioning tracer tests show nearly 80% removal of the total NAPL content from the test cell. The field data suggest that a somewhat higher level of removal could be achieved with a longer alcohol injection.

  20. Synthesis of polymer gel electrolyte with high molecular weight poly(methyl methacrylate)-clay nanocomposite

    International Nuclear Information System (INIS)

    Meneghetti, Paulo; Qutubuddin, Syed; Webber, Andrew

    2004-01-01

    Polymer nanocomposite gel electrolytes consisting of high molecular weight poly(methyl methacrylate) PMMA-clay nanocomposite, ethylene carbonate (EC)/propylene carbonate (PC) as plasticizer, and LiClO 4 electrolyte are reported. Montmorillonite clay was ion exchanged with a zwitterionic surfactant (octadecyl dimethyl betaine) and dispersed in methyl methacrylate, which was then polymerized to synthesize PMMA-clay nanocomposites. The nanocomposite was dissolved in a mixture of EC/PC with LiClO 4 , heated and pressed to obtain polymer gel electrolyte. X-ray diffraction (XRD) of the gels indicated intercalated clay structure with d-spacings of 2.85 and 1.40 nm. In the gel containing plasticizer, the clay galleries shrink suggesting intercalation rather than partial exfoliation observed in the PMMA-clay nanocomposite. Ionic conductivity varied slightly and exhibited a maximum value of 8 x 10 -4 S/cm at clay content of 1.5 wt.%. The activation energy was determined by modeling the conductivity with a Vogel-Tamman-Fulcher expression. The clay layers are primarily trapped inside the polymer matrix. Consequently, the polymer does not interact significantly with LiClO 4 electrolyte as shown by FTIR. The presence of the clay increased the glass transition temperature (Tg) of the gel as determined by differential scanning calorimetry. The PMMA nanocomposite gel electrolyte shows a stable lithium interfacial resistance over time, which is a key factor for use in electrochemical applications

  1. Lithium-Salt-Containing High-Molecular-Weight Polystyrene-block-Polyethylene Oxide Block Copolymer Films.

    Science.gov (United States)

    Metwalli, Ezzeldin; Rasool, Majid; Brunner, Simon; Müller-Buschbaum, Peter

    2015-08-10

    Ionic conductivity in relation to the morphology of lithium-doped high-molecular-weight polystyrene-block-polyethylene oxide (PS-b-PEO) diblock copolymer films was investigated as solid-state membranes for lithium-ion batteries. The tendency of the polyethylene (PEO) block to crystallize was highly suppressed by increasing both the salt-doping level and the temperature. The PEO crystallites completely vanished at a salt-doping ratio of Li/EO>0.08, at which the PEO segments were hindered from entering the crystalline unit of the PEO chain. A kinetically trapped lamella morphology of PS-b-PEO was observed, due to PEO crystallization. The increase in the lamella spacing with increasing salt concentration was attributed to the conformation of the PEO chain rather than the volume contribution of the salt or the previously reported increase in the effective interaction parameter. Upon loading the salt, the PEO chains changed from a compact/highly folded conformation to an amorphous/expanded-like conformation. The ionic conductivity was enhanced by amorphization of PEO and thereby the mobility of the PEO blocks increased upon increasing the salt-doping level. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Study on antithrombotic and antiplatelet activities of low molecular weight fucoidan from Laminaria japonica

    Science.gov (United States)

    Chen, Anjin; Zhang, Fang; Shi, Jie; Zhao, Xue

    2012-06-01

    The antithrombotic and antiplatelet effects of two fucoidan fractions with low molecular weight and different sulfate content from Laminaria japonica were compared in order to examine the influence of chemical character on their antithrombotic activity and the possible mechanism. Both LMW fucoidan fractions exhibited favorable antithrombotic activity in an Fecl3-induced arterial thrombosis. The antithrombotic activity of LMW fucoidan was related with decrease of TXB2 and whole blood viscosity and hematocrit. LMW fucoidan showed a correlation between anticoagulant, antiaggregant and antithrombotic effects in vivo. For LMW fucoidan, antithrombotic activity required high dose of 5-10 nmol kg-1, concomitantly with increase in anticoagulant activity and inhibition of platelet aggregation. Administration of LMW fucoidan significantly promoted the 6-keto-PGF1α content and decreased the TXB2 content, indicating its inhibition of tissue factor pathway and regulation of metabolism of arachidonic acid. By comparison, highly sulfated fucoidan LF2 with Mw 3900 seemed to be a more suitable choice for antithrombotic drug for its antithrombotic activity accompanied with specific inhibitory activity on platelet aggregation, low anticoagulant activity and low hemorrhagic risk in vivo.

  3. Radiation resistance of ultra high molecular weight polyethylene and polyetheretherketone as materials for gasket and sealing

    International Nuclear Information System (INIS)

    Seguchi, Tadao; Nakagiri, Naotaka; Koike, Michihiro.

    1990-11-01

    Radiation resistance of ultra high molecular weight polyethylene (NL-W) and polyetheretherketone (PEEK-450G) was tested to select the gasket and sealing materials used in the piping and valve for high level radioactive liquid in reprocessing of nuclear fuel. The tensile, bending, hardness, and seal tests were carried out after 60 Co-γ-ray irradiation in air, in oxygen under pressure, and in nitric acid of 3N and 10N at room temperature. For NL-W, the degradation was small until 3.2 MGy by the irradiation in air and in nitric acid, then the sealing was maintained. However, the degradation was observed by the irradiation in oxygen under pressure, then, the physical properties and sealing would be loosed gradually with dose in air at very low dose rate irradiation. For PEEK-450G, the radiation degradation was very small in the these irradiation conditions, but it was observed to degrade in the case of high temperature in high concentration of nitric acid. (author)

  4. Immune-enhancing activities of low molecular weight {beta}-glucan depolymerized by gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Nak-Yun [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Byun, Eui-Hong [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Laboratory of Food Chemistry, Division of Applied Biological Chemistry, Department of Bioscience and Biotechnology, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581 (Japan); Kwon, Sun-Kyu; Song, Beom-Seok; Choi, Jong-il; Kim, Jae-Hun; Byun, Myung-Woo [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Yoo, Young-Choon [Department of Microbiology, College of Medicine, Konyang University, Daejeon 302-718 (Korea, Republic of); Kim, Mee-Ree [Department of Food and Nutrition, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Lee, Ju-Woon [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of)], E-mail: sjwlee@kaeri.re.kr

    2009-07-15

    {beta}-glucans are structural cell wall polymers of many microorganisms and cereals which possess immunomodulatory properties and have been used in the food, cosmetic and medical industry. In our previous study, {beta}-glucan was depolymerized by gamma irradiation and leads to improve the solubility and viscosity. This study was carried out to evaluate the functional properties, mainly immune-enhancing activities of low molecular weight {beta}-glucan fragmented by gamma irradiation. The results showed that RAW 264.7 macrophage cell stimulation activities of irradiated {beta}-glucan were higher than that of non-irradiated {beta}-glucan. In addition, the oral administration of gamma-irradiated {beta}-glucan significantly increased the proliferation and cytokine (IFN-{gamma} and IL-2) release of spleen and Peyer's patch cells compared with non-irradiated {beta}-glucan. In conclusion, gamma irradiation could be used as an effective method for the production of depolymerized {beta}-glucan improved functional property such as immunomodulatory activity.

  5. Isolation of high molecular weight DNA from marine sponge bacteria for BAC library construction.

    Science.gov (United States)

    Ouyang, Yongchang; Dai, Shikun; Xie, Lianwu; Ravi Kumar, M S; Sun, Wei; Sun, Huimin; Tang, Danling; Li, Xiang

    2010-06-01

    Metagenomics is a powerful tool for mining the genetic repositories from environmental microorganisms. Bacteria associated with marine sponges (phylum Porifera) are rich sources of biologically active natural products. However, to date, few compounds are discovered from the sponge metagenomic libraries, and the main reason might be the difficulties in recovery of high molecular weight (HMW) DNA from sponge symbionts to construct large insert libraries. Here, we describe a method to recover HMW bacterial DNA from diverse sponges with high quality for bacterial artificial chromosome (BAC) library construction. Microorganisms concentrated from sponges by differential centrifugation were embedded in agarose plugs to lyse out the HMW DNA for recovery. DNA fragments over 436 kb size were recovered from three different types of sponges, Halichondria sp., Haliclona sp., and Xestospongia sp. To evaluate the recovered DNA quality, the diversity of bacterial DNA comprised in the HMW DNA derived from sponge Halichondria sp. was analyzed, and this HMW DNA sample was also cloned into a shuttle BAC vector between Escherichia coli and Streptomyces sp. The results showed that more than five types of bacterial DNA, i.e., Proteobacteria, Nitrospirae, Cyanobacteria, Planctomycetes, and unidentified bacteria, had been recovered by this method, and an average 100 kb size insert DNA in a constructed BAC library demonstrated that the recovered HMW DNA is suitable for metagenomic library construction.

  6. Immune-enhancing activities of low molecular weight β-glucan depolymerized by gamma irradiation

    International Nuclear Information System (INIS)

    Sung, Nak-Yun; Byun, Eui-Hong; Kwon, Sun-Kyu; Song, Beom-Seok; Choi, Jong-il; Kim, Jae-Hun; Byun, Myung-Woo; Yoo, Young-Choon; Kim, Mee-Ree; Lee, Ju-Woon

    2009-01-01

    β-glucans are structural cell wall polymers of many microorganisms and cereals which possess immunomodulatory properties and have been used in the food, cosmetic and medical industry. In our previous study, β-glucan was depolymerized by gamma irradiation and leads to improve the solubility and viscosity. This study was carried out to evaluate the functional properties, mainly immune-enhancing activities of low molecular weight β-glucan fragmented by gamma irradiation. The results showed that RAW 264.7 macrophage cell stimulation activities of irradiated β-glucan were higher than that of non-irradiated β-glucan. In addition, the oral administration of gamma-irradiated β-glucan significantly increased the proliferation and cytokine (IFN-γ and IL-2) release of spleen and Peyer's patch cells compared with non-irradiated β-glucan. In conclusion, gamma irradiation could be used as an effective method for the production of depolymerized β-glucan improved functional property such as immunomodulatory activity.

  7. The effects of polymer molecular weight on filament thinning and drop breakup in microchannels

    International Nuclear Information System (INIS)

    Arratia, P E; Cramer, L-A; Gollub, J P; Durian, D J

    2009-01-01

    We investigate the effects of fluid elasticity on the dynamics of filament thinning and drop breakup processes in a cross-slot microchannel. Elasticity effects are examined using dilute aqueous polymeric solutions of molecular weight (MW) ranging from 1.5x10 3 to 1.8x10 7 . Results for polymeric fluids are compared to those for a viscous Newtonian fluid. The shearing or continuous phase that induces breakup is mineral oil. All fluids possess similar shear-viscosity (∼0.2 Pa s) so that the viscosity ratio between the oil and aqueous phases is close to unity. Measurements of filament thickness as a function of time show different thinning behavior for the different aqueous fluids. For Newtonian fluids, the thinning process shows a single exponential decay of the filament thickness. For low MW fluids (10 3 , 10 4 and 10 5 ), the thinning process also shows a single exponential decay, but with a decay rate that is slower than for the Newtonian fluid. The decay time increases with polymer MW. For high MW (10 6 and 10 7 ) fluids, the initial exponential decay crosses over to a second exponential decay in which elastic stresses are important. We show that the decay rate of the filament thickness in this exponential decay regime can be used to measure the steady extensional viscosity of the fluids. At late times, all fluids cross over to an algebraic decay which is driven mainly by surface tension.

  8. Advances in ultra high molecular weight polyethylene/hydroxyapatite composites for biomedical applications: A brief review.

    Science.gov (United States)

    Macuvele, Domingos Lusitâneo Pier; Nones, Janaína; Matsinhe, Jonas V; Lima, Marla M; Soares, Cíntia; Fiori, Márcio A; Riella, Humberto G

    2017-07-01

    Ultra high molecular weight polyethylene (UHMWPE) is a semicrystalline polymer that has been applied, as a bearing surface in total human joint replacements and artificial bones. UHMWPE has a superior wear resistance, low-friction surface, biological inertness, high levels of strength, creep resistance and low friction coefficient. However, the wear debris generated during the joint motions could cause problem in human implant, such as osteolysis and loosening. For this, several attempts was been made to improve UHMWPE properties and increases safety and biocompatibility in human implants. One of them, include the use of hydroxyapatite (HA), as reinforcement agent to modify the UHMWPE properties and facilitate biological fixation between the implant and the human cells. Recent studies showed that the addition of HA in polymer matrix result in enhancement of mechanical and tribological properties. In addition, it also improves the formation of the actual bond between the material and the living organism since the hydroxyapatite is the major component of the mineral part of the human bone. In this brief review the some properties and characteristic of UHMWPE and HA are described and main processing methods of UHMWPE/HA composites and biocompatibility studies were also reviewed. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Activation of the low molecular weight protein tyrosine phosphatase in keratinocytes exposed to hyperosmotic stress.

    Directory of Open Access Journals (Sweden)

    Rodrigo A Silva

    Full Text Available Herein, we provide new contribution to the mechanisms involved in keratinocytes response to hyperosmotic shock showing, for the first time, the participation of Low Molecular Weight Protein Tyrosine Phosphatase (LMWPTP activity in this event. We reported that sorbitol-induced osmotic stress mediates alterations in the phosphorylation of pivotal cytoskeletal proteins, particularly Src and cofilin. Furthermore, an increase in the expression of the phosphorylated form of LMWPTP, which was followed by an augment in its catalytic activity, was observed. Of particular importance, these responses occurred in an intracellular milieu characterized by elevated levels of reduced glutathione (GSH and increased expression of the antioxidant enzymes glutathione peroxidase and glutathione reductase. Altogether, our results suggest that hyperosmostic stress provides a favorable cellular environment to the activation of LMWPTP, which is associated with increased expression of antioxidant enzymes, high levels of GSH and inhibition of Src kinase. Finally, the real contribution of LMWPTP in the hyperosmotic stress response of keratinocytes was demonstrated through analysis of the effects of ACP1 gene knockdown in stressed and non-stressed cells. LMWPTP knockdown attenuates the effects of sorbitol induced-stress in HaCaT cells, mainly in the status of Src kinase, Rac and STAT5 phosphorylation and activity. These results describe for the first time the participation of LMWPTP in the dynamics of cytoskeleton rearrangement during exposure of human keratinocytes to hyperosmotic shock, which may contribute to cell death.

  10. Theoretical and Experimental Investigations of Polyelectrolyte Adsorption Dependence on Molecular Weight.

    Science.gov (United States)

    Xie, Fei; Lu, Hongduo; Nylander, Tommy; Wågberg, Lars; Forsman, Jan

    2016-06-14

    This work focuses on adsorption of polyions onto oppositely charged surfaces and on responses to the addition of a simple monovalent salt as well as to the polyion length (degree of polymerization). We also discuss possible mechanisms underlying observed differences, of the adsorbed amount on silica surfaces at high pH, between seemingly similar polyions. This involves theoretical modeling, utilizing classical polymer density functional theory (DFT). We furthermore investigate how long- and short-chain versions of the polymer adsorb onto carboxymethylated cellulose, carrying a high negative charge. Interestingly enough, comparing results obtained for the two different surfaces, we observe an opposite qualitative response for the molecular weight. The large polymer adsorbs more strongly at a silica surface, but for cellulose at low salt levels, there are indications that the trend is opposite. Another difference is the very slow adsorption process observed for cellulose, particularly with short polymers; in fact, with short polymers, we were sometimes unable to establish any adsorption plateau at all. We speculate that the slow dynamics is due to a gradual diffusion of short polymers into the cellulose matrix. This phenomenon could also explain why short-chain polymers seem to adsorb more strongly than long-chain ones, at low salt concentrations, provided that the latter then are too large to enter the cellulose pores. Cellulose swelling at high salt concentrations might diminish these differences, leading to more similar adsorbed amounts or even a lower adsorption for short chains.

  11. Chronic Toxicity Of High Molecular Weight Polynuclear Aromatic Hydrocarbon- Pyrene On Freshwater Cyanobacterium Anabaena Fertlissima Rao

    Directory of Open Access Journals (Sweden)

    Jignasha G Patel

    2013-12-01

    Full Text Available The aim of this work was to determine the consequences of Polynuclear aromatic hydrocarbon – Pyrene in response to growth, pigments and metabolic study on Anabaena fertilissima Rao. Test organisms were treated at different doses and encountered LC50 (Lethal concentration at which 50% growth reduction occur concentration separately at 1.5 mg/l, 3.0 mg/l and 6.0 mg/l respectively for Anabaena fertilissima Rao. The influence of Pyrene on growth, pigments, release of metabolites such as carbohydrates, protein, amino acid, phenols was carried out. The test doses caused a concentration dependent decrease in pigments like carotenoids and phycobilliproteins and showed more sensitivity to pyrene. Depletion of carbohydrate by 13% to 81% and proteins by 47% to 93% was encountered with rise in pyrene concentrations after 16th day of exposure. However, phenols were found to rise by 27% to 50% with increased pyrene concentrations on the contrary, amino acids were reported to decline by 79% to 92%. This study therefore suggests high molecular weight pyrene that decreases in metabolite content and enzyme activity can be used as a signal of PAHs toxicity in cyanobacteria. International Journal of Environment, Volume-2, Issue-1, Sep-Nov 2013, Pages 175-183 DOI: http://dx.doi.org/10.3126/ije.v2i1.9220

  12. Risk organ preservation technique in reirradiation. Injection of native type high molecular weight hyaluronate

    International Nuclear Information System (INIS)

    Kishi, Kazushi; Noda, Yasutaka; Tanaka, Kayo

    2012-01-01

    We developed a practical method of brachytherapy effective for reirradiation, using hyaluronate gel injection to separate the target to be intensively. We intended curative reirradiation with preserving organs at risk. Native-type high molecular weight hyaluronate that has an ideal biologic property to reduce inflammation via inhibitory activity to CD44 and other inflammation receptors was injected to create space during radiotherapy. Rectum, small intestines, skin, and various normal organs are effectively separated and thus eradicative re-irradiation was carried out in safe. We reviewed 55 patients who required the method. There were no complications related to the procedure. Prescribed dose to 100% of the planning target volume (PTV) was 77.93 Gy (range 54-92) equivalent at alpha/beta ratio of 3, with much higher subvolume effect, and the saving effects were enhanced at 3.35 times in the average of those without gel injection. In conclusion, the interventional brachytherapy with hyaluronate gel injection provided 3.35 times safer dose-escalated and eradicative treatment in reirradiation. (author)

  13. Agarotetrol: a source compound for low molecular weight aromatic compounds from agarwood heating.

    Science.gov (United States)

    Takamatsu, Sakura; Ito, Michiho

    2018-02-20

    Agarwood is known to generate a distinct fragrance upon heating and is used as both a medicine and a fragrant wood. Low molecular weight aromatic compounds (LACs) such as benzylacetone are emitted from agarwood on heating and have a sedative effect on mice. These are detected exclusively in the headspace vapor of heated agarwood and are absent in the wood itself; hence, some compounds in agarwood are thought to be converted to LACs by the process of heating. In this study, different fractions obtained from agarwood were analyzed to reveal the source compounds of LACs. Some LACs detected in the resinous agarwood were absent from the non-resinous parts and confirmed as characteristic of the resinous parts. The essential oil and hydrosol of agarwood obtained by distillation were analyzed by gas chromatography-mass spectrometry (GC-MS). Sesquiterpenes were detected in the essential oil, and sesquiterpenes and a variety of LACs were detected in the hydrosol. A hot water extract of agarwood remaining in the distillation flask after distillation was analyzed by high-performance liquid chromatography (HPLC), and agarotetrol was found to be the main compound. Purified agarotetrol was heated in a glass vial and its headspace vapor was analyzed by solid-phase microextraction GC-MS. Benzylacetone and other LACs were detected. These results indicate that agarotetrol, a chromone derivative, contributes to the fragrance of agarwood through the generation of LACs upon heating.

  14. Disappearance of a low molecular weight heparin fraction (CY 216) differs from standard heparin in rabbits

    International Nuclear Information System (INIS)

    Boneu, B.; Buchanan, M.R.; Caranobe, C.; Gabaig, A.M.; Dupouy, D.; Sie, P.; Hirsh, J.

    1987-01-01

    In previous studies, we have reported that standard heparin (SH) was cleared by two mechanisms, a saturable mechanism which predominated at low doses (less than 100 anti-factor Xa U/kg) and a non-saturable mechanism which predominated at higher doses, when the first mechanism became saturated. In this study, we examined the importance of these two mechanisms in the disappearance of a low molecular weight heparin fraction (LMWH) (CY 216), by comparing the pharmacokinetics and the pharmacodynamics of a wide range of doses of SH and CY 216 (1.5 to 500 anti-factor Xa U/kg). Pharmacokinetics was measured as the disappearance of 125 I-radiolabelled SH or CY 216. Pharmacodynamics was measured as the disappearance of the anti-factor Xa activity of SH and CY 216. We found that the saturable mechanism contributed little to the disappearance of CY 216 and that it was cleared predominantly by the non-saturable mechanism at all doses tested. Thus, at low doses (less than 100 anti-factor Xa U/kg), SH was cleared more rapidly than CY 216, whereas at higher doses, CY 216 was cleared more rapidly than SH. We conclude that the mechanism of disappearance of LMWH's differ significantly from those of SH, and that this difference may explain the apparent prolonged anticoagulant activity of LMWH's within the therapeutic range doses

  15. Extrudable polymer-polymer composites based on ultra-high molecular weight polyethylene

    Science.gov (United States)

    Panin, S. V.; Kornienko, L. A.; Alexenko, V. O.; Buslovich, D. G.; Dontsov, Yu. V.

    2017-12-01

    Mechanical and tribotechnical characteristics of polymer-polymeric composites of UHMWPE are studied with the aim of developing extrudable, wear-resistant, self-lubricant polymer mixtures for Additive Manufacturing (AM). The motivation of the study is their further application as feedstocks for 3D printing. Blends of UHMWPE with graft- and block copolymers of low-density polyethylene (HDPE-g-VTMS, HDPE-g-SMA, HDPE-b-EVA), polypropylene (PP), block copolymers of polypropylene and polyamide with linear low density polyethylene (PP-b-LLDPE, PA-b-LLDPE), as well as cross-linked polyethylene (PEX-b), are examined. The choice of compatible polymer components for an ultra- high molecular weight matrix for increasing processability (extrudability) is motivated by the search for commercially available and efficient additives aimed at developing wear-resistant extrudable polymer composites for additive manufacturing. The extrudability, mechanical properties and wear resistance of UHMWPE-based polymer-polymeric composites under sliding friction with different velocities and loads are studied.

  16. Aspect of use of ultrahigh molecular weight polyethylene (uhmwpe) as biomaterial and as armour material (abstract)

    International Nuclear Information System (INIS)

    Fuzail, M.

    2011-01-01

    Among the known polymeric materials, ultrahigh molecular weight polyethylene (UHMWPE) has unique properties as a biomaterial as well as armour material. Its high strength and very high modulus makes it an alternate candidate as body armour for example bullet proof vest. The drawn fibers from this material are best known for their break strength and compete with the steel and carbon fibers. On the other hand, its extremely high molar mass imparts outstanding wear resistance and impact toughness better than any other polymer which makes it a better choice as biomaterial used in hip and knee transplants. As a biomaterial, when body transplants are gamma sterilized, their shelf life depends upon the number and nature of free radicals produced during sterilization. These long-lived radicals ultimately affect the wear properties of hip and knee transplants. The Electron Spin Resonance (ESR) technique used to determine the concentration and nature of free radicals in about 16 years old powder, fibers and ram-extruded bar samples shows that at low microwave power (0.01 mW), polyenyl radicals become prominent while at high microwave power (160 mW), oxygen-centered radicals show their identity. The ESR study also exhibits that the concentration of free radicals depends upon the crystallinities of different morphologies known i.e powder, extruded bars and drawn fibers. Differential scanning calorimetry shows the order of crystallinity as: fiber > extruded bars > powder. (author)

  17. Biotransformation of petroleum asphaltenes and high molecular weight polycyclic aromatic hydrocarbons by Neosartorya fischeri.

    Science.gov (United States)

    Hernández-López, E Lorena; Perezgasga, Lucia; Huerta-Saquero, Alejandro; Mouriño-Pérez, Rosa; Vazquez-Duhalt, Rafael

    2016-06-01

    Neosartorya fischeri, an Aspergillaceae fungus, was evaluated in its capacity to transform high molecular weight polycyclic aromatics hydrocarbons (HMW-PAHs) and the recalcitrant fraction of petroleum, the asphaltenes. N. fischeri was able to grow in these compounds as sole carbon source. Coronene, benzo(g,h,i)perylene, and indeno(1,2,3-c,d)pyrene, together with the asphaltenes, were assayed for fungal biotransformation. The transformation of the asphaltenes and HMW-PAHs was confirmed by reverse-phase high-performance liquid chromatography (HPLC), nano-LC mass spectrometry, and IR spectrometry. The formation of hydroxy and ketones groups on the PAH molecules suggest a biotransformation mediated by monooxygenases such as cytochrome P450 system (CYP). A comparative microarray with the complete genome from N. fischeri showed three CYP monooxygenases and one flavin monooxygenase genes upregulated. These findings, together with the internalization of aromatic substrates into fungal cells and the microsomal transformation of HMW-PAHs, strongly support the role of CYPs in the oxidation of these recalcitrant compounds.

  18. Blends of low molecular weight of poly lactic acid (PLA) with gondorukem (gum rosin)

    Science.gov (United States)

    Kaavessina, Mujtahid; Distantina, Sperisa; Chafidz, Achmad; Utama, Aditya; Anggraeni, Venisa Mega Puteri

    2018-02-01

    The utilization of plastic was increasing as well as the increasing its demand in wide range application. Consequently, the number of plastic litter will increase and make more serious environmental problems. This research concerns to minimize waste problems by designing biodegradable plastic. In this research, biodegradable plastic was made of poly lactic acid (PLA) and gondorukem (Gum rosin, Resina colophonium) as the plasticizer. The effect of gondorukem towards PLA properties such as rheology and degradability was investigated. The research divided into two steps: (i) the polycondensation of lactic acid (LA) and (ii) modification of obtained poly lactic acid. In the first step, polycondensation was done in N2 atmosphere (138°C) for 30 hours and added 0.1 %w of SnCl2 as catalyst. Bulk modification was conducted by blending of gondurukem in varied weight (0.5, 1, and 2 g in 10 g of PLA). Furthermore, the modified PLA was analyzed its molecular structure, biodegradability and rheological property. The presence of gondorukem enhanced the biodegradability of poly lactic acid. Gondorukem could act as the plasticizer. It is confirmed that the complex viscosity of PLA melt decreased upon the addition of gondorukem

  19. Surface functionalization of solid state ultra-high molecular weight polyethylene through chemical grafting

    Science.gov (United States)

    Sherazi, Tauqir A.; Rehman, Tayyiba; Naqvi, Syed Ali Raza; Shaikh, Ahson Jabbar; Shahzad, Sohail Anjum; Abbas, Ghazanfar; Raza, Rizwan; Waseem, Amir

    2015-12-01

    The surface of ultra-high molecular weight polyethylene (UHMWPE) powder was functionalized with styrene using chemical grafting technique. The grafting process was initiated through radical generation on base polymer matrix in the solid state by sodium thiosulfate, while peroxides formed at radical sites during this process were dissociated by ceric ammonium nitrate. Various factors were optimized and reasonably high level of monomer grafting was achieved, i.e., 15.6%. The effect of different acids as additive and divinyl benzene (DVB) as a cross-linking agent was also studied. Post-grafting sulfonation was conducted to introduce the ionic moieties to the grafted polymer. Ion-exchange capacity (IEC) was measured experimentally and is found to be 1.04 meq g-1, which is in close agreement with the theoretical IEC values. The chemical structure of grafted and functionalized polymer was characterized by attenuated total reflection infrared spectroscopy (ATR-FTIR) and thermal properties were investigated by thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Thermal analysis depicts that the presence of radicals on the polymer chain accelerates the thermal decomposition process. The results signify that the chemical grafting is an effective tool for substantial surface modification and subsequent functionalization of polyethylene.

  20. Use of low molecular weight heparin in pregnant women with mechanical heart valves.

    Science.gov (United States)

    Yinon, Yoav; Siu, Samuel C; Warshafsky, Chelsie; Maxwell, Cynthia; McLeod, Anne; Colman, Jack M; Sermer, Mathew; Silversides, Candice K

    2009-11-01

    There are a number of different anticoagulation options for pregnant women with mechanical heart valves. The purpose of this study was to examine maternal thromboembolic complications in women with mechanical valves treated with low-molecular weight heparin (LMWH) throughout pregnancy. This was a substudy of a larger prospective cohort study of pregnant women with heart disease followed from 1998 to 2008. All pregnant women with mechanical left-sided valves who were treated with LMWH throughout pregnancy were included. Maternal thromboembolic events were defined as valve thrombosis, need for valve replacement, or stroke during pregnancy or postpartum (up to 6 months). Twenty-three pregnancies (17 women) occurred in women treated with LMWH and low-dose aspirin: 15 in women with mechanical mitral valves, 9 in women with mechanical aortic valves, and 1 in a woman with both. There was 1 maternal thromboembolic event (4%), which resulted in maternal and fetal death. Five women (22%) developed other adverse cardiac events during pregnancy. Nine pregnancies (43%) had fetal or neonatal adverse events, 5 of which had favorable outcomes. Three pregnancies were complicated by postpartum hemorrhage. In conclusion, carefully monitored LMWH may be a suitable anticoagulation strategy in pregnant women with mechanical heart valves who are unwilling to use warfarin. However, this group of women remains at risk for maternal cardiac and fetal complications. The occurrence of valve thrombosis resulting in maternal death despite therapeutic anti-Xa levels highlights current limitations with anticoagulation in this population.

  1. Characterization of low molecular weight protein tyrosine phosphatase isoforms in human breast cancer epithelial cell lines.

    Science.gov (United States)

    Alho, Irina; Costa, Luís; Bicho, Manuel; Coelho, Constança

    2013-05-01

    Low molecular weight protein tyrosine phosphatase (LMW-PTP) is a polymorphic protein with two major isoforms whose role in tumorigenesis is currently controversial. We characterized LMW-PTP genotype, isoform expression and activity in six different human breast cancer epithelial cell lines (ZR75, MDA-MB-231, MDA-MB-231BO, MCF7, MDA-MB-231BO2, MDA-MB-435) and compared them with MCF10A, a normal breast epithelial cell line. mRNA expression of the slow isoform was increased in almost all breast cancer cell lines and that of the fast isoform was reduced (p<0.05) in all breast cancer cell lines. Regarding enzymatic activity, only MCF7 had significantly lower (p<0.05) LMW-PTP activity compared to MCF10A. Since these are novel and previously unreported findings, we propose that the differential expression of LMW-PTP fast and slow isoforms suggests their opposite roles in the tumorigenic process, with the fast isoform being anti-oncogenic and the slow isoform being oncogenic.

  2. Low Molecular Weight Chitosan-Coated PLGA Nanoparticles for Pulmonary Delivery of Tobramycin for Cystic Fibrosis

    Directory of Open Access Journals (Sweden)

    Nusaiba K. Al-Nemrawi

    2018-03-01

    Full Text Available (1 Background: Poly(lactic-co-glycolic acid (PLGA nanoparticles (NPs loaded with Tobramycin were prepared using a solvent-evaporation method. (2 Methods: The NPs were coated with low molecular weight chitosan (LMWC to enhance the mucoadhesiveness of PLGA-NPs. The following w/w ratios of tobramycin to LMWC were prepared: control (0:0.50, F0 (1:0.25, F0.5 (1:0.5, and F1 (1:1. (3 Results: The results showed that the size of the particles increased from 220.7 nm to 575.77 nm as the concentration of LMWC used in the formulation increased. The surface charge was also affected by the amount of LMWC, where uncoated-PLGA nanoparticles had negative charges (−2.8 mV, while coated-PLGA NPs had positive charges (+33.47 to +50.13 mV. SEM confirmed the size and the spherical homogeneous morphology of the NPs. Coating the NPs with LMWC enhanced the mucoadhesive properties of the NPs and sustained the tobramycin release over two days. Finally, all NPs had antimicrobial activity that increased as the amount of LMWC increased. (4 Conclusion: In conclusion, the formulation of mucoadhesive, controlled-release, tobramycin-LMWC-PLGA nanoparticles for the treatment of P. aeruginosa in cystic fibrosis patients is possible, and their properties could be controlled by controlling the concentration of LMWC.

  3. Mapping of low molecular weight heparins using reversed phase ion pair liquid chromatography-mass spectrometry.

    Science.gov (United States)

    Li, Daoyuan; Chi, Lequan; Jin, Lan; Xu, Xiaohui; Du, Xuzhao; Ji, Shengli; Chi, Lianli

    2014-01-01

    Low molecular weight heparins (LMWHs) are structurally complex, highly sulfated and negatively charged, linear carbohydrate polymers prepared by chemical or enzymatic depolymerization of heparin. They are widely used as anticoagulant drugs possessing better bioavailability, longer half-life, and lower side effects than heparin. Comprehensive structure characterization of LMWHs is important for drug quality assurance, generic drug application, and new drug research and development. However, fully characterization of all oligosaccharide chains in LMWHs is not feasible for current available analytical technologies due to their structure complexity and heterogeneity. Fingerprinting profiling is an efficient way for LMWHs' characterization and comparison. In this work, we present a simple, sensitive, and powerful analytical approach for structural characterization of LMWHs. Two different LMWHs, enoxaparin and nadroparin, were analyzed using reversed phase ion pair electrospray ionization mass spectrometry (RPIP-ESI-MS). More than 200 components were identified, including major structures, minor structures, and process related impurities. This approach is robust for high resolution and complementary fingerprinting analysis of LMWHs. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Efficient aquatic bacterial metabolism of dissolved low-molecular-weight compounds from terrestrial sources.

    Science.gov (United States)

    Berggren, Martin; Laudon, Hjalmar; Haei, Mahsa; Ström, Lena; Jansson, Mats

    2010-03-01

    Carboxylic acids (CAs), amino acids (AAs) and carbohydrates (CHs) in dissolved free forms can be readily assimilated by aquatic bacteria and metabolized at high growth efficiencies. Previous studies have shown that these low-molecular-weight (LMW) substrates are released by phytoplankton but also that unidentified LMW compounds of terrestrial origin is a subsidy for bacterial metabolism in unproductive freshwater systems. We tested the hypothesis that different terrestrially derived CA, AA and CH compounds can offer substantial support for aquatic bacterial metabolism in fresh waters that are dominated by allochthonous dissolved organic matter (DOM). Drainage water from three catchments of different characters in the Krycklan experimental area in Northern Sweden were studied at the rising and falling limb of the spring flood, using a 2-week bioassay approach. A variety of CA, AA and CH compounds were significantly assimilated by bacteria, meeting 15-100% of the bacterial carbon demand and explaining most of the observed variation in bacterial growth efficiency (BGE; R(2)=0.66). Of the 29 chemical species that was detected, acetate was the most important, representing 45% of the total bacterial consumption of all LMW compounds. We suggest that LMW organic compounds in boreal spring flood drainage could potentially support all in situ bacterial production in receiving lake waters during periods of weeks to months after the spring flood.

  5. Preparation of High Modulus Poly(Ethylene Terephthalate: Influence of Molecular Weight, Extrusion, and Drawing Parameters

    Directory of Open Access Journals (Sweden)

    Jian Min Zhang

    2017-01-01

    Full Text Available Poly(ethylene terephthalate (PET which is one of the most commercially important polymers, has for many years been an interesting candidate for the production of high performance fibres and tapes. In current study, we focus on investigating the effects of the various processing variables on the mechanical properties of PET produced by a distinctive process of melt spinning and uniaxial two-stage solid-state drawing (SSD. These processing variables include screw rotation speed during extrusion, fibre take-up speed, molecular weight, draw-ratio, and drawing temperature. As-spun PET production using a single-screw extrusion process was first optimized to induce an optimal polymer microstructure for subsequent drawing processes. It was found that less crystallization which occurred during this process would lead to better drawability, higher draw-ratio, and mechanical properties in the subsequent SSD process. Then the effect of drawing temperature (DT in uniaxial two-stage SSD process was studied to understand how DT (

  6. Characterization and quantitation of low and high molecular weight phenolic compounds in apple seeds.

    Science.gov (United States)

    Fromm, Matthias; Bayha, Sandra; Carle, Reinhold; Kammerer, Dietmar R

    2012-02-08

    The phenolic constituents of seeds of 12 different apple cultivars were fractionated by sequential extraction with aqueous acetone (30:70, v/v) and ethyl acetate after hexane extraction of the lipids. Low molecular weight phenolic compounds were individually quantitated by RP-HPLC-DAD. The contents of extractable and nonextractable procyanidins were determined by applying RP-HPLC following thiolysis and n-butanol/HCl hydrolysis, respectively. As expected, the results revealed marked differences of the ethyl acetate extracts, aqueous acetone extracts, and insoluble residues with regard to contents and mean degrees of polymerization of procyanidins. Total phenolic contents in the defatted apple seed residues ranged between 18.4 and 99.8 mg/g. Phloridzin was the most abundant phenolic compound, representing 79-92% of monomeric polyphenols. Yields of phenolic compounds significantly differed among the cultivars under study, with seeds of cider apples generally being richer in phloridzin and catechins than seeds of dessert apple cultivars. This is the first study presenting comprehensive data on the contents of phenolic compounds in apple seeds comprising extractable and nonextractable procyanidins. Furthermore, the present work points out a strategy for the sustainable and complete exploitation of apple seeds as valuable agro-industrial byproducts, in particular as a rich source of phloridzin and antioxidant flavanols.

  7. Preparation of low molecular weight Sargassum fusiforme polysaccharide and its anticoagulant activity

    Science.gov (United States)

    Sun, Yuhao; Chen, Xiaolin; Liu, Song; Yu, Huahua; Li, Rongfeng; Wang, Xueqin; Qin, Yukun; Li, Pengcheng

    2017-10-01

    Heparin has been used as an anticoagulant drug for many years, but it has significant side effects. In the search for good substitutes, low molecular weight (MW) polysaccharides from Sargassum fusiforme have been examined and confirmed to possess biological activities. Here, S. fusiforme polysaccharides (SFP) were extracted and subjected to a hydrogen peroxide (H2O2) oxidation method for the preparation of low-MW SFP (LSFP). The effects of temperature, pH, and H2O2 concentration on the degradation process were also examined. Several LSFP of 36, 9, 5.7, and 2.7 kDa were obtained under different conditions, and their anticoagulant activities studied in vitro. The results showed that SFP and LSFP prolonged activated partial thromboplastin (APTT), prothrombin (PT) and thrombin times (TT) significantly, indicating that these low MW polysaccharides possessed anticoagulant activity in the intrinsic, extrinsic, and common coagulation pathways. As these effects were related to the MW of the polysaccharides in APTT and TT but not in PT, the contents of the monosaccharide fucose and sulfate and the polysaccharide MW could have exerted combined effects. The details of this mechanism require further verification.

  8. Influence of Low Molecular Weight Organic Acids on Transport of Cadmium and Copper Ions across Model Phospholipid Membranes

    Czech Academy of Sciences Publication Activity Database

    Parisová, Martina; Navrátil, Tomáš; Šestáková, Ivana; Jaklová Dytrtová, Jana; Mareček, Vladimír

    2013-01-01

    Roč. 8, č. 1 (2013), s. 27-44 ISSN 1452-3981 R&D Projects: GA AV ČR IAA400400806 Institutional support: RVO:61388963 ; RVO:61388955 Keywords : cadmium * copper * low molecular weight organic acid Subject RIV: CG - Electrochemistry Impact factor: 1.956, year: 2013

  9. Influence of low-molecular-weight glutenin subunit haplotypes on dough rheology in elite common wheat varieties

    Science.gov (United States)

    The low molecular weight glutenin subunits (LMW-GSs) are a class of wheat seed storage proteins. They are encoded by a multigene family located at the Glu-3 loci, and their allelic variation strongly influences wheat end-use quality. Due to ambiguities in the LMW-GS allele nomenclature and to the co...

  10. Low-molecular-weight heparin versus standard heparin in general and orthopaedic surgery: a meta-analysis

    NARCIS (Netherlands)

    Nurmohamed, M. T.; Rosendaal, F. R.; Büller, H. R.; Dekker, E.; Hommes, D. W.; Vandenbroucke, J. P.; Briët, E.

    1992-01-01

    Low-molecular-weight heparins (LMWHs) have theoretical advantages over standard heparin as postoperative thromboprophylactic agents. We conducted a meta-analysis of studies reported between 1984 and April, 1991, in which LMWHs were compared with standard heparin for postoperative prophylaxis. We

  11. Development of gel-filter method for high enrichment of low-molecular weight proteins from serum.

    Directory of Open Access Journals (Sweden)

    Lingsheng Chen

    Full Text Available The human serum proteome has been extensively screened for biomarkers. However, the large dynamic range of protein concentrations in serum and the presence of highly abundant and large molecular weight proteins, make identification and detection changes in the amount of low-molecular weight proteins (LMW, molecular weight ≤ 30kDa difficult. Here, we developed a gel-filter method including four layers of different concentration of tricine SDS-PAGE-based gels to block high-molecular weight proteins and enrich LMW proteins. By utilizing this method, we identified 1,576 proteins (n = 2 from 10 μL serum. Among them, 559 (n = 2 proteins belonged to LMW proteins. Furthermore, this gel-filter method could identify 67.4% and 39.8% more LMW proteins than that in representative methods of glycine SDS-PAGE and optimized-DS, respectively. By utilizing SILAC-AQUA approach with labeled recombinant protein as internal standard, the recovery rate for GST spiked in serum during the treatment of gel-filter, optimized-DS, and ProteoMiner was 33.1 ± 0.01%, 18.7 ± 0.01% and 9.6 ± 0.03%, respectively. These results demonstrate that the gel-filter method offers a rapid, highly reproducible and efficient approach for screening biomarkers from serum through proteomic analyses.

  12. Rapid Analysis of Apolar Low Molecular Weight Constituents in Wood Using High Pressure Liquid Chromatography with Evaporative Light Scattering Detection

    NARCIS (Netherlands)

    Claassen, F.W.; Haar, van de C.; Beek, van T.A.; Dorado, J.; Martinez-Inigo, M.; Sierra-Alvarez, R.

    2000-01-01

    A new high pressure liquid chromatographic method with evaporative light scattering detection was developed for the qualitative and quantitative analysis of apolar, low molecular weight constituents in wood. The wood extractives were obtained by means of a 6 h Soxhlet extraction with acetone. The

  13. Molecular weight and amino acid composition of the exocellular dd-carboxypeptidase–transpeptidase of Streptomyces R61

    Science.gov (United States)

    Frère, Jean-Marie; Ghuysen, Jean-Marie; Perkins, Harold R.; Nieto, Manuel

    1973-01-01

    A procedure allowing the purification of milligram amounts of the exocellular dd-carboxypeptidase–transpeptidase from Streptomyces R61 to protein homogeneity (95% purity) is described. The isolated protein has a molecular weight of about 38000 and consists of one polypeptide chain. Its amino acid composition is presented. ImagesPLATE 1 PMID:4772272

  14. Hyaluronated mesoporous silica nanoparticles for active targeting: influence of conjugation method and hyaluronic acid molecular weight on the nanovector properties.

    Science.gov (United States)

    Ricci, Valentina; Zonari, Daniele; Cannito, Stefania; Marengo, Alessandro; Scupoli, Maria Teresa; Malatesta, Manuela; Carton, Flavia; Boschi, Federico; Berlier, Gloria; Arpicco, Silvia

    2018-04-15

    We have prepared and evaluated the physico-chemical and biological properties of four different hyaluronated mesoporous silica nanoparticles (MSNs) samples (MSN/HA). Hyaluronic acid (HA) with two different molecular weights (200 and 6.4 kDa) was used for the conjugation of aminopropyl-functionalized MSN (NH 2 -MSN), following two different procedures. Namely, samples HA200A and HA6.4A were prepared by reacting activated HA with NH 2 -MSN (method A), while samples HA200B and HA6.4B were obtained carrying out HA activation in the presence of the nanoparticles (method B). The four samples showed similar hydrophilicity, but clear differences in the HA loading, textural properties, surface charge and stability of the suspensions. More in detail, conjugation using low molecular weight HA with method A resulted in low HA loading, with consequent scarce effects on dispersity and stability in physiological media. The highest yield and corresponding best performances were obtained with method B using high molecular weight HA. HA loading and molecular weight also influenced in a concerted way the biological response towards the MSNs of CD44 target cancer cells (CD44 + ) and control cells (CD44 - ): MDA-MB-231 and A2780, respectively. The absence of cytotoxicity was assessed. Moreover, the targeting ability of the best performing MSN/HA was confirmed by cellular uptake studies. Copyright © 2018 Elsevier Inc. All rights reserved.

  15. Assembled microneedle arrays enhance the transport of compounds varying over a large range of molecular weight across human dermatomed skin

    NARCIS (Netherlands)

    Verbaan, F.J.; Bal, S.M.; van den Berg, D.J.; Groenink, W.H.H.; Verpoorten, H.; Lüttge, Regina; Bouwstra, J.A.

    2007-01-01

    In this study, we demonstrate the feasibility to use microneedle arrays manufactured from commercially available 30G hypodermal needles to enhance the transport of compounds up to a molecular weight of 72 kDa. Piercing of human dermatomed skin with microneedle arrays was studied by Trypan Blue

  16. Airway morphology and function of rats following dermal sensitization and respiratory challenge with low molecular weight chemicals

    NARCIS (Netherlands)

    Arts, J.H.E.; Kuper, C.F.; Spoor, S.M.; Bloksma, N.

    1998-01-01

    Local lymph node activation and increased total serum IgE levels are suggested to be predictive parameters of airway hypersensitivity caused by low molecular weight (LMW) chemicals. Whether increases of total serum IgE are indicative of actual induction of specific airway reactions (morphological

  17. A randomized blind study comparing standard heparin and a new low molecular weight heparinoid in cardiopulmonary bypass surgery in dogs

    NARCIS (Netherlands)

    Henny, C. P.; ten Cate, H.; ten Cate, J. W.; Moulijn, A. C.; Sie, T. H.; Warren, P.; Büller, H. R.

    1985-01-01

    Postoperative hemorrhage remains a serious complication in cardiopulmonary bypass (CPB) surgery. In our study, alternative anticoagulation with a new low molecular weight (LMW) heparinoid (Org 10172) was compared with a standardized heparin regimen. A preliminary dose-finding study indicated the

  18. Size and shape of the repetitive domain of high molecular weight wheat gluten proteins. 1. Small angle neutron scattering

    NARCIS (Netherlands)

    Egelhaaf, SU; van Swieten, E; Bosma, T; de Boef, E; van Dijk, AA; Robillard, GT; Egelhaaf, Stefan U.

    The solution structure of the central repetitive domain of high molecular weight (HMW) wheat gluten proteins has been investigated for a range of concentrations and temperatures using mainly small-angle neutron scattering. A representative part of the repetitive domain (dBl) was studied as well as

  19. Alterations in total and high-molecular-weight adiponectin after 3 weeks of moderate alcohol consumption in premenopausal women

    NARCIS (Netherlands)

    Joosten, M.M.; Witkamp, R.F.; Hendriks, H.F.J.

    2011-01-01

    Moderate alcohol consumption is associated with increased concentrations of adiponectin. Whether this is the case for both total and high–molecular-weight (HMW) adiponectin is uncertain. Furthermore, the rate at which this increase occurs is unclear. Therefore, we examined the effect of moderate

  20. Influence of low-molecular-weight glutenin subunit haplotypes on dough rheology and baking quality in elite common wheat varieties

    Science.gov (United States)

    The low molecular weight glutenin subunits (LMW-GSs) are a class of wheat seed storage proteins directly involved in the formation of gluten. Depending on the first amino acid residue of the mature proteins, the LMW-GSs are divided into methionine, serine or isoleucine type. These proteins are encod...

  1. Size and shape of the repetitive domain of high molecular weight wheat gluten proteins. II. Hydrodynamic studies

    NARCIS (Netherlands)

    van Swieten, E; Friesen, RR; de Kruif, CG; Robillard, GT; Kruif, Cees G. de

    This study describes the hydrodynamic properties of the repetitive domain of high molecular weight (HMW) wheat proteins, which complement the small-angle scattering (SANS) experiments performed in the first paper of this series. The sedimentation coefficients, so, and diffusion coefficients, D, were

  2. Randomized Phase III Trial of Low Molecular Weight Heparin Enoxaparin in Addition to Standard Treatment in Small Cell Lung Cancer

    DEFF Research Database (Denmark)

    Ek, L; Gezelius, E; Bergman, B

    2018-01-01

    Background: Coagulation activation and venous thromboembolism (VTE) are hallmarks of malignant disease and represent a major cause of morbidity and mortality in cancer. Coagulation inhibition with low molecular weight heparin (LMWH) may improve survival specifically in small cell lung cancer (SCLC...

  3. Potentials and limitations of the low-molecular-weight protein lysozyme as a carrier for renal drug targeting

    NARCIS (Netherlands)

    Haverdings, RFG; Haas, M; Greupink, AR; de Vries, PAM; Moolenaar, F; de Zeeuw, D; Meijer, DKF

    2001-01-01

    Selective targeting of drugs to the kidney may enable an increased renal effectiveness combined with a reduction of extrarenal toxicity. Intrarenal delivery to the proximal tubular cell can be achieved using low-molecular-weight proteins, such as lysozyme. Administration of high dosages of lysozyme,

  4. TENSILE FORCE AT BREAK OF GEL-SPUN HOT-DRAWN ULTRAHIGH MOLECULAR-WEIGHT POLYETHYLENE FIBERS

    NARCIS (Netherlands)

    PENNING, JP; PENNINGS, AJ

    1991-01-01

    Fibres obtained by gel spinning of ultrahigh molecular weight polyethylene (UHMWPE) were drawn to various ratios, and the improvement of the tensile strength of the hot-drawn filaments with increasing draw ratio has been studied. The tensile force at break of gel-spun/hot-drawn UHMWPE fibres

  5. Comparative properties of silica- and carbon black-reinforced natural rubber in the presence of epoxidized low molecular weight polymer

    NARCIS (Netherlands)

    Saramolee, P.; Sahakaro, Kannika; Lopattananon, N.; Dierkes, Wilma K.; Noordermeer, Jacobus W.M.

    2014-01-01

    This work investigates the effect of epoxidized low molecular weight natural rubber (ELMWNR) in silica- and carbon black-filled natural rubber (NR) compounds on processing and mechanical and dynamic mechanical properties. The ELMWNRs with different mol% epoxide content were prepared from

  6. The polysaccharide and low molecular weight components of Opuntia ficus indica cladodes: Structure and skin repairing properties.

    Science.gov (United States)

    Di Lorenzo, Flaviana; Silipo, Alba; Molinaro, Antonio; Parrilli, Michelangelo; Schiraldi, Chiara; D'Agostino, Antonella; Izzo, Elisabetta; Rizza, Luisa; Bonina, Andrea; Bonina, Francesco; Lanzetta, Rosa

    2017-02-10

    The Opuntia ficus-indica multiple properties are reflected in the increasing interest of chemists in the identification of its natural components having pharmaceutical and/or cosmetical applications. Here we report the structural elucidation of Opuntia ficus-indica mucilage that highlighted the presence of components differing for their chemical nature and the molecular weight distribution. The high molecular weight components were identified as a linear galactan polymer and a highly branched xyloarabinan. The low molecular weight components were identified as lactic acid, D-mannitol, piscidic, eucomic and 2-hydroxy-4-(4'-hydroxyphenyl)-butanoic acids. A wound healing assay was performed in order to test the cicatrizing properties of the various components, highlighting the ability of these latter to fasten dermal regeneration using a simplified in vitro cellular model based on a scratched keratinocytes monolayer. The results showed that the whole Opuntia mucilage and the low molecular weight components are active in the wound repair. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Molecular weight dependent charge carrier mobility in poly(3,3' '-dioctyl-2,2':5',2' '-terthiophene).

    Science.gov (United States)

    Verilhac, Jean-Marie; Pokrop, Rafal; LeBlevennec, Gilles; Kulszewicz-Bajer, Irena; Buga, Katarzyna; Zagorska, Malgorzata; Sadki, Said; Pron, Adam

    2006-07-13

    Poly(3,3' '-dioctyl-2,2':5',2' '-terthiophene), a polymer recently used for the fabrication of organic field effect transistors, has been fractionated into five fractions distinctly differing in their molecular weights (Mn), with the goal of determining the influence of the degree of polymerization (DPn) on its principal physicochemical parameters. It has been demonstrated that within the Mn range studied (from 1.5 kDa to 10.5 kDa by SEC), corresponding to DPn from 10 to 38, the polymer band gap steadily decreases with growing molecular weight, which is clearly manifested by an increasing bathochromic shift of the band originating from the pi-pi* transition. The same trend is observed for the HOMO level, determined from the onset of the p-doping in cyclic voltammetry, which shifts from -5.10 eV to -4.90 eV for the lowest and the highest molecular weight fractions, respectively. The most pronounced influence of DPn has been found for the charge carriers' mobility-one of the most important parameters of field effect transistors (FETs) fabricated from this polymer. A fourfold increase in DPn results in an increase of the carriers' mobility by more than 3 orders of magnitude. Comparison of these results with those obtained for fractionated regioregular poly(3-hexylthiophene) shows a strikingly similar behavior of both polymers with respect to the molecular weight.

  8. Molecular Weights of Bovine and Porcine Heparin Samples: Comparison of Chromatographic Methods and Results of a Collaborative Survey.

    Science.gov (United States)

    Bertini, Sabrina; Risi, Giulia; Guerrini, Marco; Carrick, Kevin; Szajek, Anita Y; Mulloy, Barbara

    2017-07-19

    In a collaborative study involving six laboratories in the USA, Europe, and India the molecular weight distributions of a panel of heparin sodium samples were determined, in order to compare heparin sodium of bovine intestinal origin with that of bovine lung and porcine intestinal origin. Porcine samples met the current criteria as laid out in the USP Heparin Sodium monograph. Bovine lung heparin samples had consistently lower average molecular weights. Bovine intestinal heparin was variable in molecular weight; some samples fell below the USP limits, some fell within these limits and others fell above the upper limits. These data will inform the establishment of pharmacopeial acceptance criteria for heparin sodium derived from bovine intestinal mucosa. The method for MW determination as described in the USP monograph uses a single, broad standard calibrant to characterize the chromatographic profile of heparin sodium on high-resolution silica-based GPC columns. These columns may be short-lived in some laboratories. Using the panel of samples described above, methods based on the use of robust polymer-based columns have been developed. In addition to the use of the USP's broad standard calibrant for heparin sodium with these columns, a set of conditions have been devised that allow light-scattering detected molecular weight characterization of heparin sodium, giving results that agree well with the monograph method. These findings may facilitate the validation of variant chromatographic methods with some practical advantages over the USP monograph method.

  9. Molecular Weights of Bovine and Porcine Heparin Samples: Comparison of Chromatographic Methods and Results of a Collaborative Survey

    Directory of Open Access Journals (Sweden)

    Sabrina Bertini

    2017-07-01

    Full Text Available In a collaborative study involving six laboratories in the USA, Europe, and India the molecular weight distributions of a panel of heparin sodium samples were determined, in order to compare heparin sodium of bovine intestinal origin with that of bovine lung and porcine intestinal origin. Porcine samples met the current criteria as laid out in the USP Heparin Sodium monograph. Bovine lung heparin samples had consistently lower average molecular weights. Bovine intestinal heparin was variable in molecular weight; some samples fell below the USP limits, some fell within these limits and others fell above the upper limits. These data will inform the establishment of pharmacopeial acceptance criteria for heparin sodium derived from bovine intestinal mucosa. The method for MW determination as described in the USP monograph uses a single, broad standard calibrant to characterize the chromatographic profile of heparin sodium on high-resolution silica-based GPC columns. These columns may be short-lived in some laboratories. Using the panel of samples described above, methods based on the use of robust polymer-based columns have been developed. In addition to the use of the USP’s broad standard calibrant for heparin sodium with these columns, a set of conditions have been devised that allow light-scattering detected molecular weight characterization of heparin sodium, giving results that agree well with the monograph method. These findings may facilitate the validation of variant chromatographic methods with some practical advantages over the USP monograph method.

  10. [Modified Mechanism of Cell Walls from Chinese Fir Treated with Low-Molecular-Weight Phenol Formaldehyde Resin].

    Science.gov (United States)

    Huang, Yan-hui; Fei, Ben-hua; Zhao, Rong-jun

    2015-12-01

    Study on the modified mechanism of wood cell walls, it is very important for improving treatment reagents, optimizing treatment technology, and enhancing wood density, mechanical properties, dimensional stability, and so on. Samples of plantation Chinese fir were treated gradually with synthesized water-soluble low-molecular-weight phenol formaldehyde (PF) resins under vacuum and pressure. The correlated physical and chemical properties of the treated and untreated reference samples were determined by X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), and nuclear magnetic resonance spectrometer(NMR) (Using method of Cross Polarization/Magic Angle Spinning for continuous testing) with high precision and resolution. The results showed that, after treated with water-soluble low-molecular-weight PF resin, the average values of crystallinity from the treated samples were decreased obviously, and the average reduction rate was 12.67%, 11.91% and 6.26%, respectively. Comparing water-soluble, low-molecular-weight PF resin modified Chinese fir with untreated reference samples, no new chemical shifts and characteristic peaks of functional groups from esters, ethers, etc. were present by using FTIR and ¹³C NMR spectrum. It was considered that there was no distinct chemical reaction between the water-soluble low-molecular-weight PF resin and Chinese Fir cell walls. But water-soluble low-molecular-weight PF resin could enter into the structure relatively loose, large size spaces, relatively area large amorphous regions in cell walls of Chinese fir tracheids, and form physical filling, which resulting in the decreasing of relative crystallinity. This study has important reference value for the development of new wood modification reagents and the optimization of wood modification process. The findings also provide important theoretical foundation for further proving the modification mechanisms of wood cell walls and enriching the modified theories of

  11. Effects of ionizing radiation on the properties of ultra-high molecular weight polyethylene (PE-UHMW)

    International Nuclear Information System (INIS)

    Kurth, M.

    1990-01-01

    Ultra high molecular weight polyethylene (PE-UHMW) is used in most artificial joint replacement devices. Prior to implantation in biological environment, radiatin sterilization by 60 Co or electron beam is common. It is well known that polyethylene exposed to ionizing radiation of any sort undergo physical changes due to chain scission and/or crosslinking. PE-UHMW sheets, 8 mm thick, were either 60 Co or electron beam irradiated, in the range of 10-150 kGy under air or nitrogen atmoshere. The crystallinity of the irradiated samples increases with the irradiation dose. The chain scission/crosslinking events ratio determine the network structure and the sol/gel ratio. The latter was found to depend on irradiation dose, radiation atmosphere and sample thickness. Moreover 60 Co-irradiation is about 5 times more effective in forming PE-UHMW gel than electron-irradiation. Besides the degree of crosslinking, the molecular weight distribution is the main determinant of the structural properties of PE-UHMW. Low molecular weight fractions were also found. Using a dose of 30 kGy ( 60 Co in air), the average molecular weight of the soluble part after extraction decreased from originally 2.3 million g/mol to 170.000 g/mol, corresponding to a factor of about 10. These changes in molecular weight have a strong influence on the mechanical properties of PE-UHMW. Crosslinking slightly increases the yield strength, while the elongation at break decreases. Long-term compressive creep is reduced if the material is irradiated. Obviously, increased crystallinity after oxidative chain scission affects a higher deformation resistance. Radiation crosslinked structures cause a significant increase in abrasion resistance. The above described structural changes occur even upon irradiation of very low doses as used during sterilization. This study will enable to reduce the radiation sterilization damage and thus to gain long term stability of PE-UHMW medical devices. (orig./BBR)

  12. Association between Maternal Fish Consumption and Gestational Weight Gain: Influence of Molecular Genetic Predisposition to Obesity.

    Directory of Open Access Journals (Sweden)

    Sofus C Larsen

    Full Text Available Studies suggest that fish consumption can restrict weight gain. However, little is known about how fish consumption affects gestational weight gain (GWG, and whether this relationship depends on genetic makeup.To examine the association between fish consumption and GWG, and whether this relationship is dependent on molecular genetic predisposition to obesity.A nested case-cohort study based on the Danish National Birth Cohort (DNBC sampling the most obese women (n = 990 and a random sample of the remaining participants (n = 1,128. Replication of statistically significant findings was attempted in the Avon Longitudinal Study of Parents and Children (ALSPAC (n = 4,841. We included 32 body mass index (BMI associated single nucleotide polymorphisms (SNPs and 5 SNPs found associated with GWG. BMI associated SNPs were combined in a genetic risk score (GRS. Associations between consumption of fish, GRS or individual variants and GWG were analysed, and interactions between fish and the GRS or individual variants were examined.In the DNBC, each portion/week (150 g of fatty fish was associated with a higher GWG of 0.58 kg (95% CI: 0.16, 0.99, P<0.01. For total fish and lean fish, similar patterns were observed, but these associations were not statistically significant. We found no association between GRS and GWG, and no interactions between GRS and dietary fish on GWG. However, we found an interaction between the PPARG Pro12Ala variant and dietary fish. Each additional Pro12Ala G-allele was associated with a GWG of -0.83 kg (95% CI: -1.29, -0.37, P<0.01 per portion/week of dietary fish, with the same pattern for both lean and fatty fish. In ALSPAC, we were unable to replicate these findings.We found no consistent evidence of association between fish consumption and GWG, and our results indicate that the association between dietary fish and GWG has little or no dependency on GRS or individual SNPs.

  13. Association between Maternal Fish Consumption and Gestational Weight Gain: Influence of Molecular Genetic Predisposition to Obesity.

    Science.gov (United States)

    Larsen, Sofus C; Ängquist, Lars; Laurin, Charles; Morgen, Camilla S; Jakobsen, Marianne U; Paternoster, Lavinia; Smith, George Davey; Olsen, Sjurdur F; Sørensen, Thorkild I A; Nohr, Ellen A

    2016-01-01

    Studies suggest that fish consumption can restrict weight gain. However, little is known about how fish consumption affects gestational weight gain (GWG), and whether this relationship depends on genetic makeup. To examine the association between fish consumption and GWG, and whether this relationship is dependent on molecular genetic predisposition to obesity. A nested case-cohort study based on the Danish National Birth Cohort (DNBC) sampling the most obese women (n = 990) and a random sample of the remaining participants (n = 1,128). Replication of statistically significant findings was attempted in the Avon Longitudinal Study of Parents and Children (ALSPAC) (n = 4,841). We included 32 body mass index (BMI) associated single nucleotide polymorphisms (SNPs) and 5 SNPs found associated with GWG. BMI associated SNPs were combined in a genetic risk score (GRS). Associations between consumption of fish, GRS or individual variants and GWG were analysed, and interactions between fish and the GRS or individual variants were examined. In the DNBC, each portion/week (150 g) of fatty fish was associated with a higher GWG of 0.58 kg (95% CI: 0.16, 0.99, P<0.01). For total fish and lean fish, similar patterns were observed, but these associations were not statistically significant. We found no association between GRS and GWG, and no interactions between GRS and dietary fish on GWG. However, we found an interaction between the PPARG Pro12Ala variant and dietary fish. Each additional Pro12Ala G-allele was associated with a GWG of -0.83 kg (95% CI: -1.29, -0.37, P<0.01) per portion/week of dietary fish, with the same pattern for both lean and fatty fish. In ALSPAC, we were unable to replicate these findings. We found no consistent evidence of association between fish consumption and GWG, and our results indicate that the association between dietary fish and GWG has little or no dependency on GRS or individual SNPs.

  14. Functional Comparison for Lipid Metabolism and Intestinal and Fecal Microflora Enzyme Activities between Low Molecular Weight Chitosan and Chitosan Oligosaccharide in High-Fat-Diet-Fed Rats.

    Science.gov (United States)

    Chiu, Chen-Yuan; Feng, Shih-An; Liu, Shing-Hwa; Chiang, Meng-Tsan

    2017-07-24

    The present study investigated and compared the regulatory effects on the lipid-related metabolism and intestinal disaccharidase/fecal bacterial enzyme activities between low molecular weight chitosan and chitosan oligosaccharide in high-fat-diet-fed rats. Diet supplementation of low molecular weight chitosan showed greater efficiency than chitosan oligosaccharide in suppressing the increased weights in body and in liver and adipose tissues of high-fat-diet-fed rats. Supplementation of low molecular weight chitosan also showed a greater improvement than chitosan oligosaccharide in imbalance of plasma, hepatic, and fecal lipid profiles, and intestinal disaccharidase activities in high-fat-diet-fed rats. Moreover, both low molecular weight chitosan and chitosan oligosaccharide significantly decreased the fecal microflora mucinase and β-glucuronidase activities in high-fat-diet-fed rats. These results suggest that low molecular weight chitosan exerts a greater positive improvement than chitosan oligosaccharide in lipid metabolism and intestinal disaccharidase activity in high-fat-diet-induced obese rats.

  15. Hydrophobic modification of low molecular weight polyethylenimine for improved gene transfection.

    Science.gov (United States)

    Teo, Pei Yun; Yang, Chuan; Hedrick, James L; Engler, Amanda C; Coady, Daniel J; Ghaem-Maghami, Sadaf; George, Andrew J T; Yang, Yi Yan

    2013-10-01

    Hydrophobic modification of low molecular weight (LMW) polyethylenimine (PEI) is known to increase gene transfection efficiency of LMW PEI. However, few studies have explored how the conjugated hydrophobic groups influence the properties of the modified LMW PEI mainly due to difficulties in obtaining well defined final product compositions and limitations in current chemical synthesis routes. The aim of this study was to modify LMW PEI (Mn 1.8 kDa, PEI-1.8) judiciously with different hydrophobic functional groups and to investigate how hydrophobicity, molecular structure and inclusion of hydrogen bonding properties in the conjugated side groups as well as the conjugation degree (number of primary amine groups of PEI-1.8 modified with hydrophobic groups) influence PEI-1.8 gene transfection efficiency. The modified polymers were characterized for DNA binding ability, particle size, zeta potential, in vitro gene transfection efficiency and cytotoxicity in SKOV-3 human ovarian cancer and HepG2 human liver carcinoma cell lines. The study shows that modified PEI-1.8 polymers are able to condense plasmid DNA into cationic nanoparticles, of sizes ~100 nm, whereas unmodified polymer/DNA complexes display larger particle sizes of 2 μm. Hydrophobic modification also increases the zeta potential of polymer/DNA complexes. Importantly, modified PEI-1.8 shows enhanced transfection efficiency over the unmodified counterpart. Higher transfection efficiency is obtained when PEI-1.8 is modified with shorter hydrophobic groups (MTC-ethyl) as opposed to longer ones (MTC-octyl and MTC-deodecyl). An aromatic structured functional group (MTC-benzyl) also enhances transfection efficiency more than an alkyl functional group (MTC-octyl). An added hydrogen-bonding urea group in the conjugated functional group (MTC-urea) does not enhance transfection efficiency over one without urea (MTC-benzyl). The study also demonstrates that modification degree greatly influences gene transfection, and

  16. Effects of Low Molecular Weight Yeast β-Glucan on Antioxidant and Immunological Activities in Mice

    Directory of Open Access Journals (Sweden)

    Na Lei

    2015-09-01

    Full Text Available To evaluate the antioxidant and immune effects of low molecular yeast β-glucan on mice, three sulfated glucans from Saccharomyces cerevisiae (sGSCs with different molecular weight (MW and degrees of sulfation (DS were prepared. The structures of the sGSCs were analyzed through high performance liquid chromatography-gel permeation chromatography (HPLC-GPC and Fourier transform infrared spectroscopy (FTIR. sGSC1, sGSC2, and sGSC3 had MW of 12.9, 16.5 and 19.2 kDa, respectively, and DS of 0.16, 0.24 and 0.27, respectively. In vitro and in vivo experiments were conducted to evaluate the antioxidant and immunological activities of the sGSCs. In vitro experiment, the reactive oxygen species (ROS scavenging activities were determined. In vivo experiment, 50 male BALB/c mice were divided into five groups. The sGSC1, sGSC2 and sGSC3 treatment groups received the corresponding sGSCs at 50 mg/kg/day each. The GSC (glucans from Saccharomyces cerevisiae treatment group received 50 mg/kg/day GSC. The normal control group received equal volume of physiological saline solution. All treatments were administered intragastrically for 14 day. Results showed that sGSC1, sGSC2 and sGSC3 can scavenge 1,1-diphenyl-2-picryl-hydrazyl (DPPH, superoxide, and hydroxyl radicals in vitro. The strength of the radical scavenging effects of the sGSCs was in the order of sGSC1 > sGSC2 > sGSC3. Oral administration of sGSC1 significantly improved serum catalase (CAT and glutathione peroxidase (GSH-Px activities and decreased malondialdehyde (MDA level in mice. sGSC1 significantly improved the spleen and thymus indexes and the lymphocyte proliferation, effectively enhanced the percentage of CD4+ T cells, decreased the percentage of CD8+ T cells, and elevated the CD4+/CD8+ ratio. sGSC1 significantly promoted the secretion of IL-2 and IFN-γ. These results indicate that sGSC1 with low MW and DS has better antioxidant and immunological activities than the other sGSCs, and sGSC1 could

  17. Low molecular weight heparin for prevention of venous thromboembolism in patients with lower-limb immobilization.

    Science.gov (United States)

    Zee, Aniek Ag; van Lieshout, Kelly; van der Heide, Maaike; Janssen, Loes; Janzing, Heinrich Mj

    2017-08-06

    Immobilization of the lower limb is a risk factor for venous thromboembolism (VTE). Low molecular weight heparins (LMWHs) are anticoagulants, which might be used in adult patients with lower-limb immobilization to prevent deep venous thrombosis (DVT) and its complications. This is an update of the review first published in 2008. To assess the effectiveness of low molecular weight heparin for the prevention of venous thromboembolism in patients with lower-limb immobilization in an ambulatory setting. For this update, the Cochrane Vascular Information Specialist searched the Specialised Register, CENTRAL, and three trials registers (April 2017). Randomized controlled trials (RCTs) and controlled clinical trials (CCTs) that described thromboprophylaxis by means of LMWH compared with no prophylaxis or placebo in adult patients with lower-limb immobilization. Immobilization was by means of a plaster cast or brace. Two review authors independently selected trials, assessed risk of bias and extracted data. The review authors contacted the trial authors for additional information if required. Statistical analysis was carried out using Review Manager 5. We included eight RCTs that fulfilled our criteria, with a total of 3680 participants. The quality of evidence, according GRADE, varied by outcome and ranged from low to moderate. We found an incidence of DVT ranging from 4.3% to 40% in patients who had a leg injury that had been immobilized in a plaster cast or a brace for at least one week, and who received no prophylaxis, or placebo. This number was significantly lower in patients who received daily subcutaneous injections of LMWH during immobilization, with event rates ranging from 0% to 37% (odds ratio (OR) 0.45, 95% confidence interval (CI) 0.33 to 0.61; with minimal evidence of heterogeneity: I² = 26%, P = 0.23; seven studies; 1676 participants, moderate-quality evidence). Comparable results were seen in the following groups of participants: patients with below

  18. Dosimetric features and kinetic analysis of thermoluminescence from ultra-high molecular weight polyethylene

    Science.gov (United States)

    Chithambo, M. L.

    2012-08-01

    Thermoluminescence (TL) from beta irradiated ultra-high molecular weight polyethylene has been studied for measurements between 30 and 200 °C. An aliquot studied in this work produced TL glow curves consisting of two peaks, the main peak at 88 °C and a weaker intensity peak at 148 °C for heating at 1 °C s-1 following an excitation dose of 215 Gy. The position of the main peak is poorly reproducible for heating rates of 0.2 and 0.6 °C s-1 investigated with the peak position decreasing when the sample is freshly irradiated and the TL re-measured. The said change in peak position is however less of an effect for measurements made at 1 °C s-1 with the peak position being fairly reproducible in this case. Further measurements of the dosimetric properties of ultra-high molecular weight polyethylene showed that its dose response is linear from 26 Gy to about 161 Gy but exhibits slower growth in intensity with dose from about 860 Gy after regions of sub- and supra-linearity in between. If the TL is not measured immediately after irradiation, the signal fades with the delay approximately exponentially. In addition, a number of tests including phosphorescence analysis showed the possibility that the order of kinetics might not be unique but sensitive to several factors including measurement temperature. Thus for instance, the dependence of the peak position on the stop temperature in the partial heating procedure Tm - Tstop implied first-order kinetics but analysis of the geometrical factor μg for the same set of data gave μg = 0.46 ± 0.03 a value corresponding to characteristics somewhat intermediate between first and second order. In comparison, the results of analysis of the phosphorescence recorded at several temperatures on the rising edge of the main peak were only in agreement for measurements at 40 °C with general-order analysis suggesting second-order kinetics apply as did TL-like transformation of the monotonic phosphorescence decay. Both results were

  19. Low-molecular-weight heparin in women with repeated implantation failure.

    Science.gov (United States)

    Lodigiani, Corrado; Di Micco, Pierpaolo; Ferrazzi, Paola; Librè, Luca; Arfuso, Veronica; Polatti, Franco; Benigna, Michela; Michela, Benigna; Rossini, Roberta; Morenghi, Emanuela; Rota, Lidia; Brenner, Benjamin; Setti, Paolo Emanuele Levi; Paolo, Emanuele Levi Setti

    2011-07-01

    Implantation failure is common in assisted reproduction techniques (ART). The role of low-molecular-weight heparin (LMWH) is a matter of debate as a potential factor to improve implantation. To evaluate the pregnancy rate in patients with or without heparin administration. We performed a retrospective observational analysis of patients with at least two IVF/intracytoplasmic sperm injection cycles with implantation failure, screened for inherited thrombophilia and submitted to further ART cycles with or without administration of LMWH. A total of 265 patients fulfilled the enrollment criteria. Of these 149 (56%) were primary infertile and 116 (44%) were secondary infertile. Their mean age was 36.3 ± 3.6 years. We analyzed basal FSH, smoking habit, gene variants for inherited thrombophilia (i.e., MTHFR C677T, prothrombin G202A10G and Factor V Leiden). The patients underwent 569 new ART cycles: 512 (90%) without and 57 (10%) with LMWH. In total 105 clinical pregnancies were observed in 569 cycles (18.8%). The pregnancy rate was 17.19% (88/512) in patients not treated with LMWH and 29.52% (17/57) in the LMWH-treated group (p = 0.006). In women over 36 years of age the pregnancy rate was 15.53% (50/322) in nontreated versus 35.71% (10/28) in treated cycles (p = 0.007), while no difference was found in younger women. No statistical difference was found between the presence of inherited thrombophilia and pregnancy rate in treated and untreated cycles. significantly higher pregnancy rate in patients with previous ART implantation failures was observed with LMWH. Our results confirm no relation among inherited thrombophilia and pregnancy rate in patients with previous IVF implantation failures. These findings should be confirmed by randomized controlled trials before use of LMWH for ART cycles is recommended.

  20. Auricularia auricular polysaccharide-low molecular weight chitosan polyelectrolyte complex nanoparticles: Preparation and characterization

    Directory of Open Access Journals (Sweden)

    Wei Xiong

    2016-06-01

    Full Text Available Novel polyelectrolyte complex nanoparticles (AAP/LCS NPs were prepared in this study and these were produced by mixing negatively charged auricularia auricular polysaccharide (AAP with positively charged low molecular weight chitosan (LCS in an aqueous medium. The AAP was extracted and purified from auricularia auricular, and then characterized by micrOTOF-Q mass spectrometry, UV/Vis spectrophotometry, moisture analyzer and SEM. The yield, moisture, and total sugar content of the AAP were 4.5%, 6.2% and 90.12% (w/w, respectively. The AAP sample was water-soluble and exhibited white flocculence. The characteristics of AAP/LCS NPs, such as the particle size, zeta potential, morphology, FT-IR spectra, DSC were investigated. The results obtained revealed that the AAP/LCS NPs had a spherical shape with a diameter of 223 nm and a smooth surface, and the results of the FT-IR spectra and DSC investigations indicated that there was an electrostatic interaction between the two polyelectrolyte polymers. Bovine serum albumin (BSA, pI = 4.8 and bovine hemoglobin (BHb, pI = 6.8 were used as model drugs to investigate the loading and release features of the AAP/LCS NPs. The results obtained showed that the AAP/LCS NPs had a higher entrapment efficiency (92.6% for BHb than for BSA (81.5%. The cumulative release of BSA and BHb from AAP/LCS NPs after 24 h in vitro was 95.4% and 91.9%, respectively. The in vitro release demonstrated that AAP/LCS NPs provided a sustained release matrix suitable for the delivery of protein drugs. These studies demonstrate that AAP/LCS NPs have a very promising potential as a delivery system for protein drugs.

  1. Microfilamin - a new protein of the cytoskeleton with molecular weight 53,000

    Energy Technology Data Exchange (ETDEWEB)

    Fridlyanskaya, I.I.; Galaktionov, K.I.; D' yakonova, M.Yu.; Pinaev, G.P.

    1987-01-01

    The microfilaments in cultured cells participate in many vitally important processes: endocytosis, movement of cells, division, etc. One of the approaches to the study of the proteins of the microfilaments is the use of the hybridoma technique. This method permits the use of cell structures as an immunogen and the investigation of their protein assortment by means of monoclonal antibodies. Using such an approach, the authors were able to identify a protein with molecular weight 53 kilodaltons, not previously described in the microfilaments. BABL/c mice were immunized with an extract of the cytoskeleton of murine cells 3T3. It was produced by treating the cells with 0.5% Triton in a buffer stabilizing the cytoskeleton (10 mM sodium phosphate buffer, pH 6.8, 0.1 M KCl, 1 mMEGTA, 0.1 mM EDTA, 5 mM MgCl/sub 2/, and 2 M sucrose), and then with the same buffer, containing 1 micrograms/ml DNase I, 1mM PMSF, and 20 units/ml trasylol. The extract was clarified by successive centrifugation at 1000, 1200, and 10,000 g. Splenocytes of immune animals were hybridized with murine myeloma SP 2/0-Ag 14 cells and screening of the hybridomas was performed by the method of indirect immunofluorescence on murine cells of the 3T3 line stained with Coomassie blue. Data from autograph after incubation with E9-48 antibodies and /sup 125/I-labeled rabbit anti-mouse immunoglobulins are presented as well. The authors named this new technique microfilamin since it is detected in structures containing microfilaments: stress fibrils, the active edge, surface villi, and others.

  2. Lability of High Molecular Weight Dissolved Organic Matter Polysaccharides Increases with Mild Acid or Base Treatment.

    Science.gov (United States)

    Pedler Sherwood, B.; Sosa, O.; Nelson, C. E.; Repeta, D.; DeLong, E.

    2016-02-01

    Approximately 662 Pg of dissolved organic carbon (DOC) has accumulated in the global ocean, yet the biological and chemical constraints on DOC turnover remain poorly understood. High molecular weight dissolved organic matter (HMWDOM) is largely comprised of semi-labile polysaccharides. These polysaccharides resist degradation even in the presence of nutrient amendments, suggesting unknown factors of polysaccharide composition affect microbial degradation. In a series of microcosm incubations conducted at station ALOHA in the North Pacific Subtropical Gyre, we tested the affect of mild base (KOH-DOM) and acid (HCl-DOM) treatments on polysaccharide lability. KOH-DOM, HCl-DOM, and untreated HMWDOM was added to seawater from the deep chlorophyll maximum and 200m. Microcosms amended with KOH-DOM and HCl-DOM yielded higher bacterial abundance and greater carbon drawdown relative to untreated HMWDOM and unamended controls. Microcosms amended with KOH-DOM and HCl-DOM also showed significant production of fluorescent DOM (fDOM), whereas untreated HMWDOM and unamended controls showed a net decrease in fDOM as measured by parallel factor analysis of DOM excitation-emission spectra. Metagenomic analyses revealed that microcosms amended with untreated HMWDOM and controls became dominated by Alteromonas genera ( 60% total sequence reads). In contrast, KOH-DOM and HCl-DOM amended microcosms yielded greater bacterial diversity; Alteromonas genera comprised 25% of sequence reads, with differences primarily accounted for by proportional increases in vibrio, roseobacter, rugeria and marinomonas clades. Transcriptomic analyses identified differential gene expression during growth on each DOM fraction. This study provides new insight into specific chemical moieties that may limit the bacterial degradation rate of semi-labile HMWDOM in the ocean.

  3. Microfilamin - a new protein of the cytoskeleton with molecular weight 53,000

    International Nuclear Information System (INIS)

    Fridlyanskaya, I.I.; Galaktionov, K.I.; D'yakonova, M.Yu.; Pinaev, G.P.

    1987-01-01

    The microfilaments in cultured cells participate in many vitally important processes: endocytosis, movement of cells, division, etc. One of the approaches to the study of the proteins of the microfilaments is the use of the hybridoma technique. This method permits the use of cell structures as an immunogen and the investigation of their protein assortment by means of monoclonal antibodies. Using such an approach, the authors were able to identify a protein with molecular weight 53 kilodaltons, not previously described in the microfilaments. BABL/c mice were immunized with an extract of the cytoskeleton of murine cells 3T3. It was produced by treating the cells with 0.5% Triton in a buffer stabilizing the cytoskeleton (10 mM sodium phosphate buffer, pH 6.8, 0.1 M KCl, 1 mMEGTA, 0.1 mM EDTA, 5 mM MgCl 2 , and 2 M sucrose), and then with the same buffer, containing 1 micrograms/ml DNase I, 1mM PMSF, and 20 units/ml trasylol. The extract was clarified by successive centrifugation at 1000, 1200, and 10,000 g. Splenocytes of immune animals were hybridized with murine myeloma SP 2/0-Ag 14 cells and screening of the hybridomas was performed by the method of indirect immunofluorescence on murine cells of the 3T3 line stained with Coomassie blue. Data from autograph after incubation with E9-48 antibodies and 125 I-labeled rabbit anti-mouse immunoglobulins are presented as well. The authors named this new technique microfilamin since it is detected in structures containing microfilaments: stress fibrils, the active edge, surface villi, and others

  4. TLR2- and 4-independent immunomodulatory effect of high molecular weight components from Ascaris suum.

    Science.gov (United States)

    Favoretto, Bruna C; Silva, Sandriana R; Jacysyn, Jacqueline F; Câmara, Niels O S; Faquim-Mauro, Eliana L

    2014-03-01

    Components of high molecular-weight (PI) obtained from Ascaris suum extract down-regulate the Th1/Th2-related immune responses induced by ovalbumin (OVA)-immunization in mice. Furthermore, the PI down-modulates the ability of dendritic cells (DCs) to activate T lymphocytes by an IL-10-mediated mechanism. Here, we evaluated the role of toll like receptors 2 and 4 (TLR2 and 4) in the modulatory effect of PI on OVA-specific immune response and the PI interference on DC full activation. An inhibition of OVA-specific cellular and humoral responses were observed in wild type (WT) or in deficient in TLR2 (TLR2(-/-)) or 4 (TLR4(-/-)) mice immunized with OVA plus PI when compared with OVA-immunized mice. Low expression of class II MHC, CD40, CD80 and CD86 molecules was observed in lymph node (LN) cells from WT, TLR2(-/-) or TLR4(-/-) mice immunized with OVA plus PI compared with OVA-primed cells. We also verified that PI was able to modulate the activation of DCs derived from bone marrow of WT, TLR2(-/-) or TLR4(-/-) mice induced in vitro by agonists of TLRs, as observed by a decreased expression of class II MHC and costimulatory molecules and by low secretion of pro-inflammatory cytokines. Its effect was accompanied by IL-10 synthesis. In this sense, the modulatory effect of PI on specific-immune response and DC activation is independent of TLR2 or TLR4. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Efficacy and safety of once daily low molecular weight heparin (tinzaparin sodium) in high risk pregnancy.

    LENUS (Irish Health Repository)

    Ní Ainle, Fionnuala

    2008-10-01

    Low molecular weight heparin (LMWH) is widely regarded as the anticoagulant treatment of choice for the prevention and treatment of venous thromboembolism during pregnancy. However, previous studies have demonstrated that the pharmacokinetic profiles of LMWH vary significantly with increasing gestation. Consequently, it remains unclear whether LMWH regimens recommended for use in nonpregnant individuals can be safely extrapolated to pregnant women. The aims of this study were to assess the safety and the efficacy of tinzaparin sodium (Innohep) administered only once daily during pregnancy. A systematic retrospective review identified a cohort of 37 high-risk pregnancies which had been managed using tinzaparin 175 IU\\/kg once daily. In 26 cases, the index pregnancy had been complicated by development of an acute venous thromboembolism (17 deep vein thrombosis and nine pulmonary embolism). For each individual, case notes were examined and data extracted using a predetermined questionnaire. No episodes of recurrent venous thromboembolism were identified amongst this cohort of pregnancies managed using once daily LMWH administration. However, two unusual thrombotic complications were observed, including a parietal infarct in one patient, and a postpartum cerebral venous thrombosis in another. Once daily tinzaparin was well tolerated, with no cases of heparin-induced thrombocytopaenia, symptomatic osteoporosis, or foetal malformations. Tinzaparin dose modification based upon peak anti-Xa levels occurred in 45% of the cases examined. The present study is the largest study to have examined the clinical efficacy of once daily LMWH for use in pregnant women at high risk of venous thromboembolism. Our data support the safety and efficacy of antenatal tinzaparin at a dose of 175 IU\\/kg. In order to determine whether this once daily regimen provides equivalent (or indeed greater) thromboprophylaxis to twice daily LMWH regimens during pregnancy will require highly powered

  6. Aspirin and low-molecular weight heparin combination therapy effectively prevents recurrent miscarriage in hyperhomocysteinemic women.

    Directory of Open Access Journals (Sweden)

    Pratip Chakraborty

    Full Text Available The management of recurrent pregnancy loss (RPL still remains a great challenge, and women with polycystic ovarian syndrome (PCOS are at a greater risk for spontaneous abortion. Treatment with low-molecular-weight heparin (LMWH has become an accepted treatment option for women with RPL; however, the subgroup of women, who are likely to respond to LMWH, has not been precisely identified. The present study evaluated the efficacy of LMWH with reference to PCOS and associated metabolic phenotypes including hyperhomocysteinemia (HHcy, insulin resistance (IR and obesity. This prospective observational study was conducted at Institute of Reproductive Medicine, Kolkata, India. A total of 967 women with history of 2 or more consecutive first trimester abortions were screened and 336 were selected for the study. The selected patients were initially divided on the basis of presence or absence of PCOS, while subsequent stratification was based on HHcy, IR and/or obesity. The subjects had treatment with aspirin during one conception cycle and aspirin-LMWH combined anticoagulant therapy for the immediate next conception cycle, if the first treated cycle was unsuccessful. Pregnancy salvage was the sole outcome measure. The overall rate of pregnancy salvage following aspirin therapy was 43.15%, which was mostly represented by normohomocysteinemic women, while the salvage rate was lower in the HHcy populations irrespective of the presence or absence of PCOS, IR, or obesity. By contrast, aspirin-LMWH combined therapy could rescue 66.84% pregnancies in the aspirin-failed cases. Logistic regression analyses showed that HHcy remained a significant factor in predicting salvage rates in the PCOS, IR, and obese subpopulations controlled for other confounding factors. With regard to pregnancy salvage, combined anticoagulant therapy with aspirin and LMWH conferred added benefit to those with HHcy phenotype.

  7. Low Molecular Weight Heparin Improves Endothelial Function in Pregnant Women at High Risk of Preeclampsia.

    Science.gov (United States)

    McLaughlin, Kelsey; Baczyk, Dora; Potts, Audrey; Hladunewich, Michelle; Parker, John D; Kingdom, John C P

    2017-01-01

    Low molecular weight heparin (LMWH) has been investigated for the prevention of severe preeclampsia, although the mechanisms of action are unknown. The objective of this study was to investigate the cardiovascular effects of LMWH in pregnant women at high risk of preeclampsia. Pregnant women at high risk of preeclampsia (n=25) and low-risk pregnant controls (n=20) at 22 to 26 weeks' gestation underwent baseline cardiovascular assessments. High-risk women were then randomized to LMWH or saline placebo (30 mg IV bolus and 1 mg/kg subcutaneous dose). Cardiovascular function was assessed 1 and 3 hours post randomization. The in vitro endothelial effects of patient serum and exogenous LMWH on human umbilical venous endothelial cells were determined. High-risk women demonstrated a reduced cardiac output, high resistance hemodynamic profile with impaired radial artery flow-mediated dilation compared with controls. LMWH increased flow-mediated dilation in high-risk women 3 hours after randomization compared with baseline and increased plasma levels of placental growth factor, soluble fms-like tyrosine kinase-1, and myeloperoxidase. Serum from high-risk women impaired endothelial cell angiogenesis and increased PlGF-1 and PlGF-2 transcription compared with serum from low-risk controls. Coexposure of high-risk serum with LMWH improved the in vitro angiogenic response such that it was equivalent to that of low-risk serum and promoted placental growth factor secretion. LMWH improves maternal endothelial function in pregnant women at high risk of developing preeclampsia, possibly mediated through increased placental growth factor bioavailability. © 2016 American Heart Association, Inc.

  8. Anticoagulant-free Genius haemodialysis using low molecular weight heparin-coated circuits.

    Science.gov (United States)

    Frank, Rolf Dario; Müller, Ute; Lanzmich, Regina; Groeger, Christian; Floege, Jürgen

    2006-04-01

    Regional citrate anticoagulation or saline flushes are often used in haemodialysis patients at high risk of bleeding. In an alternative approach we evaluated the effects of covalent circuit coating with low molecular weight heparin (LMWH) for intermittent haemodialysis. In vitro, we compared the thrombogenicity of an uncoated polyvinylchloride (PVC) tubing set with LMWH-coated tubing (AOThel) and a reference tubing with end-point attached heparin coating (Carmeda Bioactive surface) under dynamic blood contact. In vivo, five chronic haemodialysis patients were studied using the Genius dialysis system and F60S filters. Each patient underwent three dialysis sessions separated by a standard haemodialysis each: (1) standard dialysis (uncoated circuit and regular dalteparin dosage), (2) dialysis with LMWH-coated circuit and regular dalteparin dosage and (3) dialysis with a completely LMWH-coated circuit without anticoagulant use. In vitro, both coated tubings showed significantly reduced thrombin-antithrombin (TAT) complex levels compared with PVC. The reference coating (Carmeda) released substantial antifactor Xa (antiXa) activity into the plasma. The LMWH coating (AOThel) released low antiXa activity only during the initial rinsing. In vivo, all dialysis sessions were well tolerated and completed without major clotting. Antithrombin levels and platelet counts were similar in all groups. P-selectin and D-dimer levels increased similarly in all groups. TAT levels were comparable in all groups during the first 3 h and significantly increased in the anticoagulant-free group after the fourth hour. LMWH surface coating reduces thrombogenicity in vitro without releasing significant amounts of heparin from the surface. In vivo, anticoagulant-free haemodialysis using a completely LMWH-coated circuit is feasible and safe in stable chronic dialysis patients with normal coagulation.

  9. Targeted Polymeric Nanoparticles for Brain Delivery of High Molecular Weight Molecules in Lysosomal Storage Disorders.

    Directory of Open Access Journals (Sweden)

    Marika Salvalaio

    Full Text Available Lysosomal Storage Disorders (LSDs are a group of metabolic syndromes, each one due to the deficit of one lysosomal enzyme. Many LSDs affect most of the organ systems and overall about 75% of the patients present neurological impairment. Enzyme Replacement Therapy, although determining some systemic clinical improvements, is ineffective on the CNS disease, due to enzymes' inability to cross the blood-brain barrier (BBB. With the aim to deliver the therapeutic enzymes across the BBB, we here assayed biodegradable and biocompatible PLGA-nanoparticles (NPs in two murine models for LSDs, Mucopolysaccharidosis type I and II (MPS I and MPS II. PLGA-NPs were modified with a 7-aminoacid glycopeptide (g7, yet demonstrated to be able to deliver low molecular weight (MW molecules across the BBB in rodents. We specifically investigated, for the first time, the g7-NPs ability to transfer a model drug (FITC-albumin with a high MW, comparable to the enzymes to be delivered for LSDs brain therapy. In vivo experiments, conducted on wild-type mice and knockout mouse models for MPS I and II, also included a whole series of control injections to obtain a broad preliminary view of the procedure efficiency. Results clearly showed efficient BBB crossing of albumin in all injected mice, underlying the ability of NPs to deliver high MW molecules to the brain. These results encourage successful experiments with enzyme-loaded g7-NPs to deliver sufficient amounts of the drug to the brain district on LSDs, where exerting a corrective effect on the pathological phenotype.

  10. High molecular weight constituents from roots of Echinacea pallida: an arabinogalactan-protein and an arabinan.

    Science.gov (United States)

    Thude, Sebastian; Classen, Birgit

    2005-05-01

    This investigation shows structural features of two macromolecules from roots of Echinacea pallida (Nutt.) Nutt: an arabinogalactan-protein (AGP) and an arabinan. The arabinogalactan-protein was precipitated with beta-glucosyl Yariv reagent from a high molecular weight fraction. Investigations of the neutral sugar composition revealed Gal (52.1% w/w) and Ara (38.2% w/w) in a ratio of 1.4:1, accompanied by Glc (6.9% w/w) and Rha (2.8% w/w). The content of uronic acids was 6.2%. Mild acid hydrolysis detects Ara and Glc being located at the periphery of the molecule. Linkage analyses and NMR spectroscopy revealed a backbone of the polysaccharide mainly consisting of 3-linked and 3,6-linked Galp-residues. Side chains are composed of 3,6-linked or 6-linked Galp terminating in 5-linked Araf, terminal Araf, Glcp and GlcAp. The protein part (3.9% w/w) of the AGP is rich in Hyp, Ser, Ala, Thr, Glu, Asp and Gly. The amount of Hyp was determined by a colorimetric method and found to be (0.65% (w/w) of the AGP, which is in good agreement with the result obtained by amino acid hydrolysis (0.67% w/w). The arabinan was isolated from the supernatant of the Yariv precipitation on the basis of solubility in EtOH (80%). It mainly consists of Ara (85.8%). Linkage analyses and NMR spectroscopy indicate a highly branched molecule, consisting of 3,5-linked, 5-linked and terminal Araf-residues in equal amounts.

  11. Effect of low molecular weight heparin (enoxaparin) on congenital cataract surgery.

    Science.gov (United States)

    Caça, Ihsan; Sahin, Alparslan; Cingü, Abdullah Kürsat; Ari, Seyhmus; Alakuş, Fuat; Cinar, Yasin

    2012-01-01

    To assess the efficacy of intracameral enoxaparin (a low-molecular-weight heparin) infusion, in variable doses on postoperative inflammatory response in congenital cataract surgery. It is a prospective, randomized controlled trial. Eighty eyes of 53 children with congenital cataract were enrolled in this study. Every eye had primary posterior capsulorrhexis and intraocular lens (IOL) implantation after lens aspiration. The eyes were divided into 4 equal groups. In group 1 balanced salt solution (BSS) without enoxaparin was used as an irrigation solution. Whereas in group 2, 3 and 4, 40mg, 20mg and 10mg enoxaparin in 500mL BSS was used respectively. The inflammatory response in the anterior chamber was compared among the groups with slit-lamp biomicroscopy. The mean follow-up period was (17.75±3.95) months in group 1, (18.00±5.15) months in group 2, (19.20±5.47) months in group 3 and (18.65±5.16) months in group 4. Mean number of inflammatory cells in the anterior chamber in group 1 was significantly higher than that of group 2, 3, 4 (P0.05). There were IOL precipitates in 4 eyes of group 1 and 2 eyes of group 4. IOL precipitate formation was significantly higher in group 1 than that of group 2 and 3 in which there was no IOL precipitate (P=0.048). There was IOL subluxation in only one eye of group 1, 3 and 4 while no subluxation was observed in group 2 (P>0.05). There was no statistically significant difference detected about IOL subluxation occurance in all 4 groups (P>0.05). Complications of cataract surgery in congenital cataract patients associated with postoperative inflammatory response found to be decreased with the use of enoxaparin in intraocular infusion solutions. Furthermore according to our results the anti-inflammatory effect of enoxaparin was dose dependant.

  12. Detoxification of Atrazine by Low Molecular Weight Thiols in Alfalfa (Medicago sativa).

    Science.gov (United States)

    Zhang, Jing Jing; Xu, Jiang Yan; Lu, Feng Fan; Jin, She Feng; Yang, Hong

    2017-10-16

    Low molecular weight (LMW) thiols in higher plants are a group of sulfur-rich nonprotein compounds and play primary and multiple roles in cellular redox homeostasis, enzyme activities, and xenobiotics detoxification. This study focused on identifying thiols-related protein genes from the legume alfalfa exposed to the herbicide atrazine (ATZ) residues in environment. Using high-throughput RNA-sequencing, a set of ATZ-responsive thiols-related protein genes highly up-regulated and differentially expressed in alfalfa was identified. Most of the differentially expressed genes (DEGs) were involved in regulation of biotic and abiotic stress responses. By analyzing the genes involved in thiols-mediated redox homeostasis, we found that many of them were thiols-synthetic enzymes such as γ-glutamylcysteine synthase (γECS), homoglutathione synthetase (hGSHS), and glutathione synthetase (GSHS). Using liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS), we further characterized a group of ATZ-thiols conjugates, which are the detoxified forms of ATZ in plants. Cysteine S-conjugate ATZ-HCl+Cys was the most important metabolite detected by MS. Several other ATZ-conjugates were also examined as ATZ-detoxified metabolites. Such results were validated by characterizing their analogs in rice. Our data showed that some conjugates under ATZ stress were detected in both plants, indicating that some detoxified mechanisms and pathways can be shared by the two plant species. Overall, these results indicate that LMW thiols play critical roles in detoxification of ATZ in the plants.

  13. Changes in blood aggregation with differences in molecular weight and degree of deacetylation of chitosan

    International Nuclear Information System (INIS)

    Hattori, Hidemi; Ishihara, Masayuki

    2015-01-01

    Because the molecular weight (Mw) and degree of deacetylation (DDA) of chitosan can vary depending on the purification method, the identification of appropriate chitosan structures is important for developing more effective hemostatic agents. In this study, the influence of varying Mw and DDA of chitosan on blood aggregation was characterized by 10 types of chitosan with different Mw and DDA, including oligomers. The highest aggregation of whole blood, washed erythrocytes and platelets in platelet-rich plasma (PRP) were observed in chitosan with Mw of 8.6 kDa or more and with DDA of 75 to 88%. However, chitosan with too high Mw (247 kDa) inhibited the aggregation of whole blood, washed erythrocytes and PRP at high chitosan concentration. At certain concentrations, chitosan with 75–85% DDA and 50–190 kDa and chitosan with 87.6% DDA and 247 kDa both aggregated proteins in PRP. Chitosan oligomer did not affect blood aggregation. The results suggested that the aggregation by chitosan depended on the interaction of positively charged chitosan with negatively charged erythrocytes, platelets and plasma protein. It seemed that a suitable balance of positive charge in chitosan and negative charge in hemocytes and some kinds of proteins was important. To develop a hemostatic with effective blood aggregation, the chitosan should not be limited to a single Mw and a single DDA but may be a mixed chitosan with wide range of Mw (8.6–247 kDa) and DDA of 75 to 88%. (paper)

  14. Antifungal activity of low molecular weight chitosan produced from non-traditional marine resources

    Directory of Open Access Journals (Sweden)

    Francisco Pires Avelelas

    2014-06-01

    Full Text Available The four plants pathogens, Botrytis cinerea, Phytophthora cinnamomi, Cryphonectria parasitica and Heterobasidion annosum are responsible for several diseases affecting different plant species in Portugal, such as pines (H. annosum, chestnuts (P. cinnamomi and C. parasitica and eucalyptus (B. cinerea. These pathogens incurs in large economic losses, and ultimately causes the death of these plants. The use of biopolymers as antimicrobial agents, such as chitosan (derived from chitin, is increasing, in order to reduce the negative impact of conventional chemical treatments on the environment, avoiding health risks. Therefore, eco-friendly polymers were produced through (1 N-acetylation with addition of acetic anhydride and (2 hydrogen peroxide of chitosan samples, obtained from two different sources: shrimp (commercial chitosan and swimming crab bycatch specie Polybius henslowii. The chemical structure and molecular weight of the prepared chitosan derivatives, water soluble chitosan (WSC and chitooligosaccharides (COS, was confirmed by Fourier Transform Infrared (FT-IR and Gel Permeation Chromatography (GPC and their antifungal activity evaluated against Botrytis cinerea, Phytophthora cinnamomi, Cryphonectria parasitica and Heterobasidion annosum. The concentration range varied from 0.0125 to 0.1 mg/mL and inhibition percentages were determined by differences in radial growth on the agar plates for all species. Although not all species tested exhibited equal vulnerability towards the concentrations range, antifungal activity of chitosan samples proved to be dependent, increasing the inhibitory capacity with lower concentrations. The results obtained support the use of chitosan fromPolybius henslowii when compared with commercial chitosan with shrimp towards antifungal approaches, suggesting that chitin producers can rely on this crab waste as a raw material for chitin extraction, adding value to this bycatch specie. Financial support was obtained

  15. Treatment of lower extremity superficial vein thrombosis with low molecular weight heparin.

    Science.gov (United States)

    Dzupina, A; Wald, M; Lee, B B; Stvrtinova, V

    2016-01-01

    The aim of our study was to ascertain the efficacy of low-molecular-weight heparin (LMWH) in the treatment of patients with SVT. A group of 336 outpatients with clinical diagnosis of SVT was evaluated in this prospective study. At the beginning of the study all patients were examined by clinical investigation, laboratory tests and duplex ultrasound investigation (examination). All patients included into the study were treated with LMWH. Clinical and ultrasound evaluation was carried out on days 10, 30 and 90 of the follow-up. This clinical study of SVT treatment with LMWH was organized in 18 outpatient departments in the Slovak Republic. After 10 days of treatment with LMWH in full therapeutic dosage, an improvement in the clinical symptoms was demonstrated in 93 % of patients; a complete resolution of clinical symptoms was demonstrated in 4 % of patients. On day 30 (after 10 days of LMWH treatment in full therapeutic dosage and further treatment in halved therapeutic dosage up to 20 days) a complete resolution of clinical symptoms was observed in 59 % (n = 189) of patients. Patients were further clinically evaluated on day 90, after two months of no anticoagulation treatment. The clinical evaluation revealed a complete resolution of symptoms in 88 % (n = 283) of patients and improvement in symptoms in 11.6 % (n = 34). Two patients developed pulmonary embolization; extension of SVT was seen in one patient and SVT recurrence in two patients. Superficial vein thrombosis can propagate into the deep veins with the risk of pulmonary embolism. The results indicate that current ambulatory treatment regimen using LMWH in the treatment of SVT is effective and safe (Fig. 4, Ref. 30).

  16. Low molecular weight heparin attenuates multiple organ failure in a murine model of disseminated intravascular coagulation.

    Science.gov (United States)

    Slofstra, Sjoukje H; van 't Veer, Cornelis; Buurman, Wim A; Reitsma, Pieter H; ten Cate, Hugo; Spek, C Arnold

    2005-06-01

    Bacterial sepsis causes widespread vascular inflammation that frequently leads to disseminated intravascular coagulation (DIC). Although intravascular coagulation contributes to organ failure, it is often debated whether anticoagulant therapy produces any beneficial effects in patients with DIC. The aim of this study was to document potential beneficial effects of low molecular weight heparin (LMWH) in a lipopolysaccharide-induced DIC model. Controlled animal experiment combined with an in vitro laboratory study. Academic research laboratory. C57BL/6 mice subjected to two injections of Serratia Marcescens lipopolysaccharide (LPS) resulting in the generalized Shwartzman's reaction as a model for DIC. LMWH (5 IU of anti-Xa activity) or saline was administered before both LPS injections and 10 hrs after the first exposure to LPS. To test the effect of LMWH on LPS-driven monocyte inflammatory responses, a human monocyte-human umbilical vein endothelial cell co-culture was used to determine E-selectin expression as a marker of monocyte adherence. In our murine DIC model, LMWH had no effect on markers of inflammation. In addition, no effect of LMWH was detected on monocyte adherence in the human monocyte-human umbilical vein endothelial cell co-culture. Organ damage, contrarily, was significantly reduced as determined by hepatic necrosis (p < .05), lung epithelial protein leakage (p < .05), and creatinine release from kidneys into plasma (p < .01). LMWH protection from organ failure resulted in an increase in survival (p = .06) in this model for DIC. These results demonstrate the significance of blood coagulation in the progression of DIC and hint at a beneficial role for LMWH anticoagulation in the management of DIC.

  17. Profile of low molecular weight tinzaparin sodium for anticoagulation during hemodialysis

    Directory of Open Access Journals (Sweden)

    Al-Saran Khalid

    2010-01-01

    Full Text Available Low-molecular-weight heparin (LMWH has been suggested as providing safe, effi-cient, convenient, and possibly more cost-effective anticoagulation for hemodialysis (HD than un-fractionated heparin (UFH with a single bolus dose at the start of hemodialysis effectively pre-vents clot formation in the dialyzer and bubble trap with fewer side-effects and possible benefits on uremic dyslipidemia. In this study, we compared the safety, clinical efficacy, and cost effectiveness of Tinzaparin sodium (Innohep with unfractionated heparin (UFH in 23 chronic HD patients; their extracorporeal anticoagulant protocol-consisted of UFH was switched to Tinzaparin for a period of 6 months. Clinical clotting (grade 1-4 was evaluated by visual inspection after blood draining of the air trap every hour and the dialyzer after each session. Anticoagulation with Tinzaparin sodium re-sulted in less frequent dialyzer and air-trap clotting compared to UFH (P= 001 and 0.04 respec-tively. Over 24 weeks, we observed no alteration in the serum lipid profile of the patients. There was a statistically significant improvement in the dialysis single pool Kt/V after 6 months of Tinza-parin use (1.40 ± 0.28 for Tinzaparin versus 1.23 ± 0.28 for heparin without any modification in the hemodialysis prescription. The total cost for 24 weeks use of Tinzaparin sodium was 23% more expensive compared to that for UFH. We conclude that a single bolus of Tinzaparin sodium injec-tion at the start of the dialysis session was more effective and convenient in our patients than UFH, but at a higher total cost. Furthermore, at least on the short term, there was no observed benefit on the lipid profile.

  18. Mucin Agarose Gel Electrophoresis: Western Blotting for High-molecular-weight Glycoproteins.

    Science.gov (United States)

    Ramsey, Kathryn A; Rushton, Zachary L; Ehre, Camille

    2016-06-14

    Mucins, the heavily-glycosylated proteins lining mucosal surfaces, have evolved as a key component of innate defense by protecting the epithelium against invading pathogens. The main role of these macromolecules is to facilitate particle trapping and clearance while promoting lubrication of the mucosa. During protein synthesis, mucins undergo intense O-glycosylation and multimerization, which dramatically increase the mass and size of these molecules. These post-translational modifications are critical for the viscoelastic properties of mucus. As a result of the complex biochemical and biophysical nature of these molecules, working with mucins provides many challenges that cannot be overcome by conventional protein analysis methods. For instance, their high-molecular-weight prevents electrophoretic migration via regular polyacrylamide gels and their sticky nature causes adhesion to experimental tubing. However, investigating the role of mucins in health (e.g., maintaining mucosal integrity) and disease (e.g., hyperconcentration, mucostasis, cancer) has recently gained interest and mucins are being investigated as a therapeutic target. A better understanding of the production and function of mucin macromolecules may lead to novel pharmaceutical approaches, e.g., inhibitors of mucin granule exocytosis and/or mucolytic agents. Therefore, consistent and reliable protocols to investigate mucin biology are critical for scientific advancement. Here, we describe conventional methods to separate mucin macromolecules by electrophoresis using an agarose gel, transfer protein into nitrocellulose membrane, and detect signal with mucin-specific antibodies as well as infrared fluorescent gel reader. These techniques are widely applicable to determine mucin quantitation, multimerization and to test the effects of pharmacological compounds on mucins.

  19. A randomized double-blind study of low-molecular-weight heparin (parnaparin) for superficial vein thrombosis: STEFLUX (Superficial ThromboEmbolism and Fluxum).

    Science.gov (United States)

    Cosmi, B; Filippini, M; Tonti, D; Avruscio, G; Ghirarduzzi, A; Bucherini, E; Camporese, G; Imberti, D; Palareti, G

    2012-06-01

    Optimal doses and duration of low-molecular-weight heparin (LMWH) for the treatment of superficial vein thrombosis (SVT) are still uncertain. To compare the efficacy and safety of different doses and durations of LMWH parnaparin for symptomatic lower limb SVT. Outpatients with at least a 4-cm-long SVT of long or short saphenous veins or their collaterals were randomized to receive parnaparin either 8500 UI once daily ( o.d.) for 10 days followed by placebo for 20 days (group A) or 8500 UI o.d. for 10 days followed by 6400 UI once daily (o.d.) for 20 days (group B) or 4250 UI o.d. for 30 days (group C) in a double-blind fashion in 16 clinics. Primary outcome was the composite of symptomatic and asymptomatic deep vein thrombosis (DVT), symptomatic pulmonary embolism (PE) and relapse and/or symptomatic or asymptomatic SVT recurrence in the first 33 days with 60 days follow-up. Among 664 patients, primary outcome occurred in 33/212 (15.6%), 4/219 (1.8%) and 16/217 (7.3%) subjects in groups A, B and C, respectively (B vs. A: absolute risk reduction [ARR]: 13.7%, 95% confidence intervals [CI]: 8-18.9 PThrombosis and Haemostasis.

  20. Calibration with Absolute Shrinkage

    DEFF Research Database (Denmark)

    Øjelund, Henrik; Madsen, Henrik; Thyregod, Poul

    2001-01-01

    In this paper, penalized regression using the L-1 norm on the estimated parameters is proposed for chemometric je calibration. The algorithm is of the lasso type, introduced by Tibshirani in 1996 as a linear regression method with bound on the absolute length of the parameters, but a modification...

  1. Approach to Absolute Zero

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 6. Approach to Absolute Zero 0.3 K. to a Few Milli-Kelvin. R Srinivasan. Series Article Volume 2 Issue 6 June 1997 pp 6-14. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/002/06/0006-0014 ...

  2. Approach to Absolute Zero

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 2. Approach to Absolute Zero From 4. 22 K. to 0. 3 K. R Srinivasan. Series Article Volume 2 Issue 2 February 1997 pp 8-16. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/002/02/0008-0016 ...

  3. Approach to Absolute Zero

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 10. Approach to Absolute Zero Below 10 milli-Kelvin. R Srinivasan. Series Article Volume 2 Issue 10 October 1997 pp 8-16. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/002/10/0008-0016 ...

  4. Approach to Absolute Zero

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 10. Approach to Absolute Zero Below 10 milli-Kelvin. R Srinivasan. Series Article Volume 2 Issue 10 October 1997 pp 8-16. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/002/10/0008-0016 ...

  5. The relevance of molecular weight in the design of amorphous biodegradable polymers with optimized shape memory effect.

    Science.gov (United States)

    Petisco-Ferrero, S; Fernández, J; Fernández San Martín, M M; Santamaría Ibarburu, P A; Sarasua Oiz, J R

    2016-08-01

    The shape memory effect (SME) has long been the focus of interest of many research groups that have studied many facets of it, yet to the authors' knowledge some molecular parameters, such as the molecular weight, have been skipped. Thus, the aim of this work is to offer further insight into the shape memory effect, by disclosing the importance of the molecular weight as the relevant parameter dictating the extension of the rubbery plateau, which is the scenario where the entropic network of entanglements manifests. For this, a set of biodegradable amorphous poly(rac-d,l)lactides have been synthesised by ring opening copolymerization of a racemic mixture of L-and D-lactide. The analysis performed on the synthesised enantiomeric copolylactides includes the determination of molecular weights by means of Gel Permeation Chromatography (GPC), thermal properties by Differential Scanning Calorimetry (DSC), dynamic mechanical analysis (DMA) and rheological tests using small amplitude oscillatory flow analysis. Shape memory properties have been determined by means of specific cyclic thermo-mechanic test protocol. It has been shown that the recovery capacity of amorphous PDLLA is linked to the disentanglement time through an exponential law. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Zwitterionic Polymer P(AM-DMC-AMPS as a Low-Molecular-Weight Encapsulator in Deepwater Drilling Fluid

    Directory of Open Access Journals (Sweden)

    Xin Zhao

    2017-06-01

    Full Text Available In deepwater oil and gas drilling, the high-molecular-weight encapsulator aggravates the thickening of the drilling fluid at low temperatures. Therefore, it is hard to manage the downhole pressure, and drilling fluid loss occurs. In this paper, a zwitterionic polymer P(AM-DMC-AMPS which was the terpolymer of acrylamide, methacrylatoethyl trimethyl ammonium chloride, and 2-acrylamido-2-methylpropane sulfonic acid, was developed as a low-molecular-weight encapsulator. It was characterized by Fourier transform infrared spectrum analysis, nuclear magnetic resonance, and gel permeation chromatography. Moreover, the low-temperature rheology, shale inhibition and filtration properties of water-based drilling fluids (WBDFs containing different encapsulators were experimentally investigated and compared. The results showed that the molecular weight of P(AM-DMC-AMPS was about 260,000, much lower than that of the conventional encapsulators. In the deepwater drilling temperature range 4–75 °C, WBDF containing P(AM-DMC-AMPS had lower and more stable rheological property because of its short molecular chains. The high shale recovery rate and low swelling rate indicated its strong shale inhibition performance, owing to its adsorption on the clay surface and the wrapping effect through both hydrogen bonding and electrostatic interaction. It also improved the filtration property of WBDF, and was compatible with other WBDF components. This product is expected to simultaneously realize the good encapsulation performance and low-temperature rheological property for deepwater drilling fluid.

  7. Tuning molecular weights of Bombyx mori (B. mori) silk sericin to modify its assembly structures and materials formation.

    Science.gov (United States)

    Yang, Mingying; Shuai, Yajun; Zhou, Guanshan; Mandal, Namita; Zhu, Liangjun; Mao, Chuanbin

    2014-08-27

    Bombyx mori (B. mori) silk sericin is a protein with features desirable as a biomaterial, such as increased hydrophilicity and biodegradation, as well as resistance to oxidation, bacteria, and ultraviolet light. In contrast to other widely studied B. mori silk proteins such as fibroin, sericin is still unexplored as a building block for fabricating biomaterial, and thus a facile technique of processing it into a material is needed. Here, electrospinning technology was used to fabricate it into biomaterials from two forms of B. mori silk sericin with different molecular weights, one is a low (12.0 kDa) molecular sericin (LS) form and another is a high (66.0 kDa) molecular weight sericin (HS) form. Circular dichroism (CD) spectra showed that LS in hexafluoroacetone (HFA) solvent adopted a predominantly random coil conformation, whereas HS tended to form a β-sheet structure along with a large content of random coils. In addition, LS and HS in HFA solvent were found to form cylinder-like smaller nanoparticles and larger irregular aggregates before electrospinning, respectively. As a result, biomaterials based on microparticles and nanofibers were successfully fabricated by electrospinning of LS and HS dissolved in HFA, respectively. The cell viability and differentiation assay indicated that nanofibers and microparticles improved cell adhesion, growth, and differentiation, proving that the scaffolds electrospun from sericin are biocompatible regardless of its molecular weight. The microparticles, not common in electrospinning of silk proteins reported previously, were found to promote the osteogenic differentiation of mesenchymal stem cells in comparison to the nanofibers. This study suggested that molecular weight of sericin mediates its secondary structure and assembly structure, which in turn leads to a control of final morphology of the electrospun materials. The microparticles and nanofibers of sericin can be potentially used as building blocks for fabricating

  8. Resorbable elastomeric networks prepared by photocrosslinking of high-molecular-weight poly(trimethylene carbonate) with photoinitiators and poly(trimethylene carbonate) macromers as crosslinking aids

    NARCIS (Netherlands)

    Bat, Erhan; van Kooten, Theo G.; Feijen, Jan; Grijpma, Dirk W.

    Resorbable and elastomeric poly( trimethylene carbonate) (PTMC) networks were efficiently prepared by photoinitiated crosslinking of linear high-molecular-weight PTMC To crosslink PTMC films, low-molecular-weight PTMC macromers with methacrylate end groups were synthesized and used as crosslinking

  9. Resorbable elastomeric networks prepared by photocrosslinking of high-molecular-weight poly(trimethylene carbonate) with photoinitiators and poly(trimethylene carbonate) macromers as crosslinking aids

    NARCIS (Netherlands)

    Bat, E.; van Kooten, Theo G.; Feijen, Jan; Grijpma, Dirk W.

    2011-01-01

    Resorbable and elastomeric poly(trimethylene carbonate) (PTMC) networks were efficiently prepared by photoinitiated crosslinking of linear high-molecular-weight PTMC. To crosslink PTMC films, low-molecular-weight PTMC macromers with methacrylate end groups were synthesized and used as crosslinking

  10. Effect of Addition of Concentrated Proteins and Seminal Plasma Low Molecular Weight Proteins in Freezing and Thawing of Equine Semen

    Directory of Open Access Journals (Sweden)

    Fagundes, B.

    2011-07-01

    Full Text Available Difficulties in obtaining equine frozen semen with potential fertility are recognized. This study was designed to investigate the effect of seminal plasma on frozen/thawing of eight stallion semen from different breed using the following treatments: Seminal plasma with ten-fold concentrated proteins with molecular weight above 10 kDa on frozen extender; Part of seminal plasma with proteins under 10 kDa on frozen extender; Conventional freezing, using whole seminal plasma on frozen extender. Using the parameter of 30% of seminal motility post-thawing as index of good freezability, it was verified an increased percentage of stallions that presented good freezability when semen was frozen with seminal plasma containing ten-fold concentrated proteins with molecular weight above 10 kDa on frozen extender. These results, suggested the use of seminal plasma concentrated proteins from own stallion to freezing/thawing semen.

  11. THE SURFACE-MEDIATED UNFOLDING KINETICS OF GLOBULAR PROTEINS IS DEPENDENT ON MOLECULAR WEIGHT AND TEMPERATURE

    Energy Technology Data Exchange (ETDEWEB)

    Patananan, A.N.; Goheen, S.C.

    2008-01-01

    The adsorption and unfolding pathways of proteins on rigid surfaces are essential in numerous complex processes associated with biomedical engineering, nanotechnology, and chromatography. It is now well accepted that the kinetics of unfolding are characterized by chemical and physical interactions dependent on protein deformability and structure, as well as environmental pH, temperature, and surface chemistry. Although this fundamental process has broad implications in medicine and industry, little is known about the mechanism because of the atomic lengths and rapid time scales involved. Therefore, the unfolding kinetics of myoglobin, β-glucosidase, and ovalbumin were investigated by adsorbing the globular proteins to non-porous cationic polymer beads. The protein fractions were adsorbed at different residence times (0, 9, 10, 20, and 30 min) at near-physiological conditions using a gradient elution system similar to that in high-performance liquid chromatography. The elution profi les and retention times were obtained by ultraviolet/visible spectrophotometry. A decrease in recovery was observed with time for almost all proteins and was attributed to irreversible protein unfolding on the non-porous surfaces. These data, and those of previous studies, fi t a positively increasing linear trend between percent unfolding after a fi xed (9 min) residence time (71.8%, 31.1%, and 32.1% of myoglobin, β-glucosidase, and ovalbumin, respectively) and molecular weight. Of all the proteins examined so far, only myoglobin deviated from this trend with higher than predicted unfolding rates. Myoglobin also exhibited an increase in retention time over a wide temperature range (0°C and 55°C, 4.39 min and 5.74 min, respectively) whereas ovalbumin and β-glucosidase did not. Further studies using a larger set of proteins are required to better understand the physiological and physiochemical implications of protein unfolding kinetics. This study confi rms that surface

  12. Low molecular weight protein enrichment on mesoporous silica thin films for biomarker discovery.

    Science.gov (United States)

    Fan, Jia; Gallagher, James W; Wu, Hung-Jen; Landry, Matthew G; Sakamoto, Jason; Ferrari, Mauro; Hu, Ye

    2012-04-17

    The identification of circulating biomarkers holds great potential for non invasive approaches in early diagnosis and prognosis, as well as for the monitoring of therapeutic efficiency.(1-3) The circulating low molecular weight proteome (LMWP) composed of small proteins shed from tissues and cells or peptide fragments derived from the proteolytic degradation of larger proteins, has been associated with the pathological condition in patients and likely reflects the state of disease.(4,5) Despite these potential clinical applications, the use of Mass Spectrometry (MS) to profile the LMWP from biological fluids has proven to be very challenging due to the large dynamic range of protein and peptide concentrations in serum.(6) Without sample pre-treatment, some of the more highly abundant proteins obscure the detection of low-abundance species in serum/plasma. Current proteomic-based approaches, such as two-dimensional polyacrylamide gel-electrophoresis (2D-PAGE) and shotgun proteomics methods are labor-intensive, low throughput and offer limited suitability for clinical applications.(7-9) Therefore, a more effective strategy is needed to isolate LMWP from blood and allow the high throughput screening of clinical samples. Here, we present a fast, efficient and reliable multi-fractionation system based on mesoporous silica chips to specifically target and enrich LMWP.(10,11) Mesoporous silica (MPS) thin films with tunable features at the nanoscale were fabricated using the triblock copolymer template pathway. Using different polymer templates and polymer concentrations in the precursor solution, various pore size distributions, pore structures, connectivity and surface properties were determined and applied for selective recovery of low mass proteins. The selective parsing of the enriched peptides into different subclasses according to their physicochemical properties will enhance the efficiency of recovery and detection of low abundance species. In combination with mass

  13. In vitro evaluation of antiviral and virucidal activity of a high molecular weight hyaluronic acid

    Directory of Open Access Journals (Sweden)

    Blasi Elisabetta

    2011-03-01

    Full Text Available Abstract Background hyaluronic acid (HA, a non-sulphated glycosaminoglycan, is present in synovial fluid, vitreous humour serum and many connective tissues. Pharmaceutical preparations of HA are used in clinical practice for wound healing, joint pain, kerato-conjunctivitis, asthma, mouth care, oesophageal-reflux, and gastritis. Moreover, it is used as a filler to counteract ageing and facial lipoatrophy. Our study aims at investigating the in vitro antiviral activity of a high molecular weight HA. Methods the MTT test was used to rule out the potential toxic effects of HA on the different cell lines used in the antiviral assays. The antiviral activity of HA against Coxsackievirus B5, Herpes Simplex Virus-1, Mumps Virus, Adenovirus-5, Influenza Virus A/H1N1, Human Herpesvirus-6, Porcine Parvovirus, Porcine Reproductive and Respiratory Syndrome Virus was assessed by virus yield assays. Results the most effective inhibition was observed against Coxsackievirus B5, with 3Log reduction of the virus yield at 4 mg/ml, and a reduction of 3.5Log and 2Log, at 2 mg/ml and 1 mg/ml, respectively: the selectivity index was 16. Mumps virus was highly inhibited too showing a reduction of 1.7Log at 1 mg/ml and 1Log at 4 mg/ml and 2 mg/ml (selectivity index = 12. The selectivity index for Influenza Virus was 12 with the highest inhibition (1Log observed at 4 mg/ml. Herpes Simplex Virus-1 and Porcine Parvovirus were mildly inhibited, whereas no antiviral activity was observed with respect to Adenovirus-5, Human Herpesvirus-6, Porcine Reproductive and Respiratory Syndrome Virus. No HA virucidal activity was ever observed against any of the viruses tested. Kinetic experiments showed that both Coxsackievirus B5 and Herpes simplex virus-1 replication were consistently inhibited, not influenced by the time of HA addition, during the virus replication cycle. Conclusions the spectrum of the antiviral activity exhibited by HA against both RNA and DNA viruses, known to have

  14. Total protein, albumin and low-molecular-weight protein excretion in HIV-positive patients

    Directory of Open Access Journals (Sweden)

    Campbell Lucy J

    2012-08-01

    Full Text Available Abstract Background Chronic kidney disease is common in HIV positive patients and renal tubular dysfunction has been reported in those receiving combination antiretroviral therapy (cART. Tenofovir (TFV in particular has been linked to severe renal tubular disease as well as proximal tubular dysfunction. Markedly elevated urinary concentrations of retinal-binding protein (RBP have been reported in patients with severe renal tubular disease, and low-molecular-weight proteins (LMWP such as RBP may be useful in clinical practice to assess renal tubular function in patients receiving TFV. We analysed 3 LMWP as well as protein and albumin in the urine of a sample of HIV positive patients. Methods In a cross-sectional fashion, total protein, albumin, RBP, cystatin C, and neutrophil gelatinase-associated lipocalin (NGAL were quantified in random urine samples of 317 HIV positive outpatients and expressed as the ratio-to-creatinine (RBPCR, CCR and NGALCR. Exposure to cART was categorised as none, cART without TFV, and cART containing TFV and a non-nucleoside reverse-transcriptase-inhibitor (TFV/NNRTI or TFV and a protease-inhibitor (TFV/PI. Results Proteinuria was present in 10.4 % and microalbuminuria in 16.7 % of patients. Albumin accounted for approximately 10 % of total urinary protein. RBPCR was within the reference range in 95 % of patients while NGALCR was elevated in 67 % of patients. No overall differences in urine protein, albumin, and LMWP levels were observed among patients stratified by cART exposure, although a greater proportion of patients exposed to TFV/PI had RBPCR >38.8 μg/mmol (343 μg/g (p = 0.003. In multivariate analyses, black ethnicity (OR 0.43, 95 % CI 0.24, 0.77 and eGFR 2 (OR 3.54, 95 % CI 1.61, 7.80 were independently associated with upper quartile (UQ RBPCR. RBPCR correlated well to CCR (r2 = 0.71, but not to NGALCR, PCR or ACR. Conclusions In HIV positive patients, proteinuria was predominantly of

  15. Inappropriate prescription of low molecular weight heparins for thromboprophylaxis among older hospitalized patients.

    Science.gov (United States)

    Garasto, Sabrina; Fusco, Sergio; Onder, Graziano; Sganga, Federica; Mammarella, Federica; Volpato, Stefano; Ruggiero, Carmelinda; Abbatecola, Angela M; Lattanzio, Fabrizia; Corsonello, Andrea

    2017-06-01

    To investigate the prevalence and clinical correlates of overprescribing and underprescribing of low molecular weight heparins (LMWHs) for thromboprophylaxis among older medical inpatients. Eight hundred seventy six patients (mean age 81.5 ± 7.6 years, female gender 57.2 %) enrolled in a multicenter observational study of seven acute care wards of geriatric medicine in Italy. The risk of venous thromboembolism was ascertained by calculating the Padua score for each patient. Patients receiving appropriate prescription of LMHW during stay were compared to those receiving LMHW with a Padua score overprescribing group). Similarly, patients with a high thromboembolic risk (Padua score ≥4) but not receiving LMHW (underprescribing group) were compared to patients appropriately not receiving LMHW during stay. Independent correlates of overprescribing and underprescribing were investigated by logistic regression analysis. Overall, 42.8 % of patients had a Padua score ≥4. LMWHs were overprescribed in 7.3 % and underprescribed in 25.2 % of patients. The number of lost basic activities of daily living (BADL) (OR = 0.25; 95 % CI 0.15-0.41) and the number of diagnoses (OR = 0.76; 95 % CI 0.61-0.95) were inversely associated with LMWH overprescription. Conversely, older age (75-84 years: OR = 2.39; 95 % CI 1.10-5.19-85 years or more: OR = 3.25, 95 % CI 1.40-7.61), anemia (OR = 1.80, 95 % CI 1.05-3.16), pressure sores (OR = 4.15, 95 % CI 1.20-14.3), number of lost BADL at the admission (OR = 3.92, 95 % CI 2.86-5.37) and number of diagnoses (OR = 1.29, 95 % CI 1.15-1.44) qualified as significant correlates of LMWH underprescription. Underprescription and, to a lesser extent, overprescription still represent an issue among older medical inpatients. Implementing risk-stratifying scores into clinical practice may improve appropriateness of LMWHs prescribing during hospitalization.

  16. Unfractionated heparin versus low-molecular-weight heparin for venous thromboembolism prophylaxis in trauma.

    Science.gov (United States)

    Jacobs, Benjamin N; Cain-Nielsen, Anne H; Jakubus, Jill L; Mikhail, Judy N; Fath, John J; Regenbogen, Scott E; Hemmila, Mark R

    2017-07-01

    Venous thromboembolism (VTE) is a common complication in trauma patients. Pharmacologic prophylaxis is utilized in trauma patients to reduce their risk of a VTE event. The Eastern Association for the Surgery of Trauma guidelines recommend use of low-molecular-weight heparin (LMWH) as the preferred agent in these patients. However, there is literature suggesting that unfractionated heparin (UFH) is an acceptable, and less costly, alternative VTE prophylaxis agent with equivalent efficacy in trauma patients. We examined data from the Michigan Trauma Quality Improvement Program to perform a comparative effectiveness study of UFH versus LMWH on outcomes for trauma patients. We conducted an analysis of the Michigan Trauma Quality Improvement Program data from January 2012 to December 2014. The data set contains information on date, time, and drug type of the first dose of VTE prophylaxis. Thirty-seven thousand eight hundred sixty-eight patients from 23 hospitals were present with an Injury Severity Score of 5 or greater and hospitalization for more than 24 hours. Patients were excluded if they died within 24 hours or received no pharmacologic VTE prophylaxis or agents other than UFH or LMWH while admitted to the hospital. We compared patients receiving LMWH to those receiving UFH. Outcomes assessed were VTE event, pulmonary embolism, deep vein thrombosis, and mortality during hospitalization. We used a generalized estimating equation approach to fit population-averaged logistic regression models with the type of first dose of VTE prophylaxis as the independent variable. Unfractionated heparin was considered the reference value. Timing of the first dose of VTE prophylaxis was entered into the model in addition to standard covariates. Odds ratios were generated for each of the dependent variables of interest. The analysis cohort consisted of 18,010 patients. Patients administered LMWH had a decreased risk of mortality (odds ratio, 0.64; confidence interval, 0

  17. Biomechanical testing of new meniscal repair techniques containing ultra high-molecular weight polyethylene suture.

    Science.gov (United States)

    Barber, F Alan; Herbert, Morley A; Schroeder, F Alexander; Aziz-Jacobo, Jorge; Sutker, Michael J

    2009-09-01

    To evaluate the biomechanical characteristics of current meniscal repair techniques containing ultra high-molecular weight polyethylene (UHMWPE) suture with and without cyclic loading. Vertical longitudinal cuts made in porcine menisci were secured with a single repair device. Noncycled and cycled (500 cycles) biomechanical tests were performed on the following groups: group 1, No. 2-0 Mersilene vertical suture (Ethicon, Somerville, NJ); group 2, No. 2-0 Orthocord vertical suture (DePuy Mitek, Westwood, MA); group 3, No. 0 Ultrabraid vertical suture (Smith & Nephew Endoscopy, Andover, MA); group 4, No. 2-0 FiberWire vertical suture (Arthrex, Naples, FL); group 5, vertically oriented mattress suture by use of an Ultra FasT-Fix device (Smith & Nephew Endoscopy) with No. 0 Ultrabraid; group 6, vertically oriented mattress suture by use of a RapidLoc A2 device (DePuy Mitek) with No. 2-0 Orthocord suture; group 7, vertically oriented stitch by use of a MaxFire device with MaxBraid PE suture (Biomet Sports Medicine, Warsaw, IN); and group 8, an obliquely oriented stitch of No. 0 UHMWPE suture inserted by use of a CrossFix device (Cayenne Medical, Scottsdale, AZ). Endpoints were failure loads, failure modes, stiffness, and cyclic displacement. Mean single-pull loads were calculated for Ultra FasT-Fix (121 N), FiberWire (110 N), MaxFire (130 N), Mersilene (84 N), Orthocord (124 N), RapidLoc A2 (86 N), CrossFix (77 N), and Ultrabraid (109 N). After 500 cyclic loads, the Orthocord (222 N) repair was stronger than the others: Ultra FasT-Fix (110 N), FiberWire (117 N), MaxFire (132 N), Mersilene (89 N), RapidLoc A2 (108 N), CrossFix (95 N), and Ultrabraid (126 N) (P Fix, RapidLoc A2, and MaxFire) were comparable to the isolated UHMWPE-containing suture repairs on single-failure load testing. UHMWPE-containing suture repairs are stronger than braided polyester suture repairs, but pure UHMWPE suture (Ultrabraid) elongated more during cycling. Orthocord suture is significantly

  18. Organic chemistry of basal ice - presence of labile, low molecular weight compounds available for microbial metabolism

    Science.gov (United States)

    Lis, Grzegorz P.; Wadham, Jemma L.; Lawson, Emily; Stibal, Marek; Telling, Jon

    2010-05-01

    Recent studies show that subglacial environments previously thought to be devoid of life contain a host of active microbial organisms. Presence of liquid water due to overburden pressure, the release of nutrients from chemical erosion of bedrock, and the potential carbon sources in overridden sediments facilitate life in this extreme environment. However, little is still known of concentrations and diversity of labile organic compounds essential for sustaining microbial metabolism in subglacial environments. Three subglacial ecosystems that considerably differ in range and amount of available organic compounds were selected for this study 1-Engabreen, northern Norway, overlying high-grade metamorphic rocks with low organic carbon content; 2-Finsterwalderbreen, Svalbard, overriding ancient black shales with a relatively high carbon content yet recalcitrant to microbiological consumption; and 3-Russell Glacier in western Greenland with recently overridden quaternary organic rich paleosols. Basal and pressure ridge ice samples were collected and subsequently analysed for low molecular weight organic compounds, with the emphasis on volatile fatty acids, carbohydrates and amino acids. The highest concentration of labile organic compounds in Greenland basal ice suggest that recently overridden paleosols have the greatest potential for sustaining microbial populations present within and underneath basal ice. The high concentration of "ancient" organic carbon in basal ice from Finsterwalderbreen, Svalbard, doesn't correlate with the presence of labile organic compounds. This indicates the inability of microbes to digest recalcitrant kerogen carbon in cold temperatures. In all three investigated environments, concentrations of labile organic compounds are elevated in basal ice with a high debris content. Until recently, most models of the global carbon cycle tend to neglect the pool of subglacial organic carbon as little is known about the range and concentrations of

  19. Colloid molecular weight estimation by gel chromatography/acrylamide gel electrophoresis

    International Nuclear Information System (INIS)

    Liberatore, F.A.; Dearborn, C.; Nigam, S.; Poon, C.; Camin, L.; Liteplo, M.

    1984-01-01

    Size or molecular weight (MW) estimation of radiolabeled collides in aqueous solutions has long been a problem. The authors have prepared several minimicroaggregated albumin colloids (mμAA) by heat denaturation of stannous-containing HSA solutions at pH 7.0, 7.5, and 8.5). The resulting colloids were labeled with Tc-99m and compared with Au-198 colloid and Tc-99m-antimony sulfide colloid (Tc-99m-Sb/sub 2/S3) by gel chromatography and gel electrophoresis. Tc-99mm-mμAA aggregated at pH 7.0 and the Au-198 colloid appeared in the external void volume of a BioRad A5.0 agarose column indicating an apparent MW of > 5 x 10/sup 6/ daltons. The pH7.5 Tc-99m-mμAA, migrated within the filtration range of the column as did a small fraction of Tc-99m-Sb/sub 2/S/sub 3/, suggesting that the MW is between 6 x 10/sup 4/ - 5 x 10/sup 6/ daltons. The Tc-99m-mμAA, aggregated at pH 8.5, had an apparent MW on gel filtration similar to that of untreated albumin, MW 6.6 x 10-/sup 4/ daltons. The mobilities of the colloids, on acrylamide disc gel electrophoresis, were consistent with the results on gel chromatography. The largest colloids, Au-198 colloid and pH 7.0 Tc-99m-mμAA, barely entered the separating gel; intermediate sized colloids, a small fraction of Tc-99m-Sb/sub 2/S/sub 3/ and pH 7.5 Tc-99m-mμAA migrated farther into the separating gel; while pH 8.5 Tc-99m-mμAA had mobility approaching that of untreated albumin. Lymphoscintigraphy studies using these colloids in animals showed the predicted, particle size-related differences in migration and clearance. The authors conclude that gel chromatography and gel electrophoresis are useful methods for estimating the apparent size of the colloidal particles

  20. Health risk assessment of exposures to a high molecular weight plasticizer present in automobile interiors.

    Science.gov (United States)

    Perez, Angela L; Liong, Monty; Plotkin, Kevin; Rickabaugh, Keith P; Paustenbach, Dennis J

    2017-01-01

    This study provides an exposure and risk assessment of diundecyl phthalate (DUP), a high molecular weight phthalate plasticizer present in automobile interiors. Total daily intake of DUP was calculated from DUP measured in wipe samples from vehicle seats from six automobiles. Four of the vehicles exhibited atypical visible surface residue on the seats. Two vehicles with no visible surface residue were sampled as a comparison. DUP was the predominant organic compound identified in each of the wipes from all seats. A risk assessment of DUP via oral, dermal, and inhalation routes resulting from contact with automobile seats was conducted. The mean, standard deviation, and maximum DUP concentrations on the seats with visible surface residue were 6983 ± 7823 μg/100 cm 2 and 38300 μg/100 cm 2 , respectively. The mean and 95th percentile of the mean for daily cumulative dose of DUP for all exposure routes for the seats with no visible surface residue ranged from 7 × 10 -4 to 4 × 10 -3  mg/kg-day and from 8 × 10 -4 to 5 × 10 -3  mg/kg-day, respectively. For seats with visible surface residue, cumulative doses ranged from 2 × 10 -3 to 2 × 10 -2  mg/kg-day and from 4 × 10 -3 to 2 × 10 -2  mg/kg-day, respectively. The estimated daily intake (contact or absorbed dose) of DUP from automobile seats were far lower than the NOAELs reported in and derived from animal studies, and are well below the reported Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Derived No Effect Levels (DNELs) for the general population. Based on this analysis, using virtually any benchmark for evaluating safety, exposure to DUP via automobile seat covers did not pose a measureable increased health-risk in any population under any reasonably plausible exposure scenario. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Relationships of Total Adiponectin and Molecular Weight Fractions of Adiponectin with Free Testosterone in African Men and Premenopausal Women

    OpenAIRE

    Cui, Jie; Wu, XiangDong; Andrel, Jocelyn; Falkner, Bonita

    2010-01-01

    Adiponectin, a protein secreted by adipose tissue, has anti-inflammatory, anti-thrombogenic and anti-diabetogenic properties. Lower plasma adiponectin levels are present in diabetes, obesity, and metabolic syndrome. Adiponectin levels are higher in women compared to men. The purpose of this study was to determine if there are relationships between total adiponectin, or the molecular weight fractions of adiponectin, with testosterone levels in African American men and pre-menopausal women. A s...

  2. Effect of molecular weight and concentration of hyaluronan on cell proliferation and osteogenic differentiation in vitro

    International Nuclear Information System (INIS)

    Zhao, Ningbo; Wang, Xin; Qin, Lei; Guo, Zhengze; Li, Dehua

    2015-01-01

    Hyaluronan (HA), the simplest glycosaminoglycan and a major component of the extracellular matrix, exists in various tissues. It is involved in some critical biological procedures, including cellular signaling, cell adhesion and proliferation, and cell differentiation. The effect of molecular weight (MW) and concentration of HA on cell proliferation and differentiation was controversial. In this study, we investigated the effect of MW and concentration of HA on the proliferation and osteogenic differentiation of rabbit bone marrow-derived stem cells in vitro. Results showed that high MW HA decreased the cell adhesion rate in a concentration-dependant manner. The cell adhesion rate was decreased by increasing MW of HA. Cell proliferation was significantly enhanced by low MW HA (P < 0.05). The factorial analysis indicated that MW and concentration had an interactive effect on the cell adhesion rate and cell proliferation (P < 0.05). High MW HA increased the mRNA expressions of ALP, RUNX-2 and OCN. The higher the MW was, the higher the mRNA expressions were. The factorial analysis indicated that MW and concentration had an interactive effect on ALP mRNA expression (P < 0.05). HA of higher MW and higher concentration promoted bone formation. These findings provide some useful information in understanding the mechanism underlying the effect of MW and concentration of HA on cell proliferation and differentiation. - Highlights: • Effect of hyaluronan on cell proliferation and differentiation is evaluated in vitro. • Hyaluronan of low molecular weight increases cell proliferation. • Hyaluronan of high molecular weight promotes cell osteogenic differentiation. • Molecular weight and concentration of hyaluronan show interactive effect

  3. The impact of low molecular weight heparin on obstetric outcomes among unexplained recurrent miscarriages complicated with methylenetetrahydrofolate reductase gene polymorphism.

    Science.gov (United States)

    Cetin, Orkun; Karaman, Erbil; Cim, Numan; Dirik, Deniz; Sahin, Hanim Guler; Kara, Erdal; Esen, Ramazan

    2017-01-01

    The association between methylenetetrahydrofolate reductase gene polymorphisms and unexplained recurrent miscarriage is elusive. The recommendations for improving pregnancy outcomes in these patients keep changing based on the available evidence. The aim of this study is to analyze the impact of low molecular weight heparin on obstetric outcomes of recurrent miscarriage patients complicated with methylenetetrahydrofolate reductase gene polymorphism. We reviewed medical records of 121 patients with a history of recurrent miscarriage complicated by methylenetetrahydrofolate reductase gene polymorphisms, retrospectively. From among them, 68 patients were treated only with folic acid and iron. The remaining 53 patients were treated with folic acid, iron and prophylactic doses of low molecular weight heparin. The subsequent pregnancy outcomes of these patients were noted. The live birth rate was higher in patients with anticoagulant therapy than in patients without anticoagulant therapy (48.5% vs. 69.8%, respectively, p: 0.015) and the congenital anomaly rate was lower in anticoagulant therapy group (17.6% vs. 3.8%, respectively, p: 0.022). The other obstetric outcomes were found to be similar between the two groups. The current study demonstrated that low molecular weight heparin improved the live birth rates among unex-plained recurrent miscarriage patients complicated with methylenetetrahydrofolate reductase gene polymorphisms. How-ever, the routine use of low molecular weight heparin did not improve the late pregnancy complications in these selected patients in the eastern region of our country. Further studies are needed to discriminate the effect of anticoagulation on the live birth rate of each of methylenetetrahydrofolate reductase gene polymorphism type.

  4. Influence of the prepolymer molecular weight and free isocyanate content on the rheology of polyurethane modified bitumens

    OpenAIRE

    Carrera Páez, Virginia; Cuadri Vega, Antonio Abad; García Morales, Moisés; Partal López, Pedro

    2014-01-01

    Isocyanate-based modification is lately gaining acceptance as a successful way to give added value to bitumen, a crude oil refining by-product. In order to study the influence of prepolymer type on the rheological properties of the resulting binders, six prepolymers synthesized from polypropylene-glycols (PPG) with varying molecular weight (between 440 and 2425) and different molar excess of a polymeric MDI (4,4’-diphenylmethane diisocyanate) were used. Two modification procedures, either inv...

  5. Effect of molecular weight and testing rate on adhesion property of pressure-sensitive adhesives prepared from epoxidized natural rubber

    International Nuclear Information System (INIS)

    Khan, Imran; Poh, B.T.

    2011-01-01

    Research highlights: → Elucidation of adhesion property of epoxidized natural rubber (ENR 25). → Correlation of peel and shear strength with molecular weight and rate of testing. → Confirmation of miscibility of tackifier and ENR 25 by DSC and FTIR study. → Applicability of Fox equation in ENR 25/coumarone-indene resin system. -- Abstract: The dependence of peel strength and shear strength of epoxidized natural rubber (ENR 25)-based pressure-sensitive adhesive on molecular weight and rate of testing was investigated using coumarone-indene as the tackifying resin. Toluene and polyethylene terephthalate (PET) were used as the solvent and substrate respectively throughout the study. A SHEEN hand coater was used to coat the adhesive on the substrate at a coating thickness of 120 μm. All the adhesion properties were determined by a Llyod Adhesion Tester operating at different rates of testing. Result shows that peel strength and shear strength increases up to an optimum molecular weight of 6.5 x 10 4 of ENR 25. For peel strength, the observation is attributed to the combined effects of wettability and mechanical strength of rubber at the optimum molecular weight, whereas for the shear strength, it is ascribed to the increasing amount of adhesive present in the coating layer which enhances the shear resistance of the adhesive. Peel strength and shear strength also increases with increase in rate of testing, an observation which is associated to the viscoeslastic response of the adhesive. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) study confirms the miscibility of tackifier and the ENR 25.

  6. Degradation kinetics of polymers in solution: Time-dependence of molecular weight distributions. [Quarterly report, January--March 1996

    Energy Technology Data Exchange (ETDEWEB)

    McCoy, B.J.; Madras, G.

    1996-02-27

    Polymer degradation occurs when polymer chains are broken under the influence of thermal, mechanical, or chemical energy. Chain-end depolymerization and random- and midpoint-chain scission are mechanisms that have been observed in liquid-phase polymer degradation. Here we develop mathematical models, unified by continuous-mixture kinetics, to show how these different mechanisms affect polymer degradation in solution. Rate expressions for the fragmentation of molecular-weight distributions (MWDs) govern the evolution of the MWDs. The governing integro-differential equations can be solved analytically for realistic conditions. Moment analysis for first-order continuous kinetics shows the temporal behavior of MWDs. Chain-end depolymerization yields monomer product and polymer molecular-weight moments that vary linearly with time. In contrast, random- and midpoint-chain scission models display exponential time behavior. The mathematical results reasonably portray experimental observations for polymer degradation. This approach, based on the time evolution of continuous distributions of chain length or molecular weight, provides a framework for interpreting several types of polymer degradation processes.

  7. Effect of Ionizing Radiation on the Chemical Structure and the Physical Properties of Polycaprolactones of Different Molecular Weight

    Directory of Open Access Journals (Sweden)

    Rodrigo Navarro

    2018-04-01

    Full Text Available Polymers used in the biomedical sector can be exposed to ionizing radiation (X-ray, gamma in vivo as implants or ex vivo for sterilization purposes (gamma, electron beam. This ionizing radiation can, at certain levels, cause degradation of the polymer. Polycaprolactones (PCL of different molecular weights were irradiated with electron beam and the changes in their chemical structure and physical properties with the dose were evaluated. Electron beam irradiation produced crosslinking and chain scission in the PCL chain without significant predominance of one mechanism over the other. Minimum dose for gelation decreased with the increase in PCL molecular weight whereas crosslinking efficiency was almost independent of PCL molecular weight. Carboxylic groups, hydroxyl groups and new saturated hydrocarbon species were detected by proton nuclear magnetic resonance (NMR. These species were consistent with a mechanism where chain scission could take place at any bond in the PCL chain with preference in the –COO–CH2– bond. Crosslinking decreased significantly the crystallization temperature of PCL. Tensile properties decreased continuously with the increase in dose. Irradiation with gamma rays produced a faster decay in mechanical properties than electron beam.

  8. Mass Spectrometry Imaging of low Molecular Weight Compounds in Garlic (Allium sativum L.) with Gold Nanoparticle Enhanced Target.

    Science.gov (United States)

    Misiorek, Maria; Sekuła, Justyna; Ruman, Tomasz

    2017-11-01

    Garlic (Allium sativum) is the subject of many studies due to its numerous beneficial properties. Although compounds of garlic have been studied by various analytical methods, their tissue distributions are still unclear. Mass spectrometry imaging (MSI) appears to be a very powerful tool for the identification of the localisation of compounds within a garlic clove. Visualisation of the spatial distribution of garlic low-molecular weight compounds with nanoparticle-based MSI. Compounds occurring on the cross-section of sprouted garlic has been transferred to gold-nanoparticle enhanced target (AuNPET) by imprinting. The imprint was then subjected to MSI analysis. The results suggest that low molecular weight compounds, such as amino acids, dipeptides, fatty acids, organosulphur and organoselenium compounds are distributed within the garlic clove in a characteristic manner. It can be connected with their biological functions and metabolic properties in the plant. New methodology for the visualisation of low molecular weight compounds allowed a correlation to be made between their spatial distribution within a sprouted garlic clove and their biological function. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  9. Amino Acid Composition, Molecular Weight Distribution and Gel Electrophoresis of Walnut (Juglans regia L. Proteins and Protein Fractionations

    Directory of Open Access Journals (Sweden)

    Xiaoying Mao

    2014-01-01

    Full Text Available As a by-product of oil production, walnut proteins are considered as an additional source of plant protein for human food. To make full use of the protein resource, a comprehensive understanding of composition and characteristics of walnut proteins are required. Walnut proteins have been fractionated and characterized in this study. Amino acid composition, molecular weight distribution and gel electrophoresis of walnut proteins and protein fractionations were analyzed. The proteins were sequentially separated into four fractions according to their solubility. Glutelin was the main component of the protein extract. The content of glutelin, albumin, globulin and prolamin was about 72.06%, 7.54%, 15.67% and 4.73% respectively. Glutelin, albumin and globulin have a balanced content of essential amino acids, except for methionine, with respect to the FAO pattern recommended for adults. SDS-PAGE patterns of albumin, globulin and glutelin showed several polypeptides with molecular weights 14.4 to 66.2 kDa. The pattern of walnut proteins in two-dimension electrophoresis (2-DE showed that the isoelectric point was mainly in the range of 4.8–6.8. The results of size exclusion chromatogram indicated molecular weight of the major components of walnut proteins were between 3.54 and 81.76 kDa.

  10. Tailoring of the Nanotexture of Mesoporous Silica Films and their Functionalized Derivatives for Selectively Harvesting Low Molecular Weight Protein

    Science.gov (United States)

    Hu, Ye; Bouamrani, Ali; Tasciotti, Ennio; Li, Li; Liu, Xuewu; Ferrari, Mauro

    2010-01-01

    We present a fast, efficient and reliable system based on mesoporous silica chips to specifically fractionate and enrich the low molecular weight proteome. Mesoporous silica thin films with tunable features at the nanoscale were fabricated using the triblock copolymer template pathway. Using different templates and concentrations in the precursor solution, various pore size distributions, pore structures and connectivity were obtained and applied for selective recovery of low mass proteins. In combination with mass spectrometry and statistic analysis, we demonstrated the correlation between the nanophase characteristics of the mesoporous silica thin films and the specificity and efficacy of low mass proteome harvesting. In addition, to overcome the limitations of the pre-functionalization method in polymer selection, plasma ashing was used for the first time for the treatment of the mesoporous silica surface prior to chemical modification. Surface charge modifications by different functional groups resulted in a selective capture of the low molecular weight proteins from serum sample. In conclusion our study demonstrates that the ability to tune the physico-chemical properties of mesoporous silica surfaces, for a selective enrichment of the low molecular weight proteome from complex biological fluids, has the potential to promote proteomic biomarker discovery. PMID:20014864

  11. The influence of gamma radiation on the molecular weight and glass transition of PLLA and HAp/PLLA nanocomposite

    International Nuclear Information System (INIS)

    Milicevic, D.; Trifunovic, S.; Dojcilovic, J.; Ignjatovic, N.; Suljovrujic, E.

    2010-01-01

    The influence of gamma radiation on the molecular weight and glass transition behaviour of poly-L-lactide (PLLA) and hydroxyapatite/poly-L-lactide (HAp/PLLA) nanocomposite has been studied. Since PLLA exposed to high-energy radiation in the presence of air is prone to chain scission reactions and large degradation, changes in molecular weight were obtained by gel permeation chromatography (GPC). Alterations in the glass transition behaviour were investigated by differential scanning calorimetry (DSC). The apparent activation energy (ΔH*) for glass transition was determined on the basis of the heating rate dependence of the glass transition temperature (T g ). Our findings support the fact that chain scission is the main reason for the decrease of T g and ΔH* with the absorbed dose. Furthermore, more intensive chain scission degradation of PLLA was observed in HAp/PLLA and can only be ascribed to the presence of HAp nanoparticles. Consequently, initial differences in the glass transition temperature and/or apparent activation energy of PLLA and HAp/PLLA became more pronounced with absorbed dose. This study reveals that radiation-induced changes in molecular weight and glass transition temperature occur in a predictable and fairly accurate manner. Therefore, gamma radiation can be used not only for sterilization but also for tailoring desirable end-use properties of these biomaterials.

  12. Effect of poly(lactide-co-glycolide) molecular weight on the release of dexamethasone sodium phosphate from microparticles.

    Science.gov (United States)

    Jaraswekin, Saowanee; Prakongpan, Sompol; Bodmeier, Roland

    2007-03-01

    The objective of this study was to investigate the effect of poly(lactide-co-glycolide) (PLGA) molecular weight (Resomer RG 502H, RG 503H, and RG 504H) on the release behavior of dexamethasone sodium phosphate-loaded microparticles. The microparticles were prepared by three modifications of the solvent evaporation method (O/W-cosolvent, O/W-dispersion, and W/O/W-methods). The encapsulation efficiency of microparticles prepared by the cosolvent- and W/O/W-methods increased from approximately 50% to >90% upon addition of NaCl to the external aqueous phase, while the dispersion method resulted in lower encapsulation efficiencies. The release of dexamethasone sodium phosphate from PLGA microparticles (>50 microm) was biphasic. The initial burst release correlated well with the porosity of the microparticles, both of which increased with increasing polymer molecular weight (RG 504H > 503H > 502H). The burst was also dependent on the method of preparation and was in the order of dispersion method > WOW method > consolvent method. In contrast to the higher molecular weight PLGA microparticles, the release from RG 502H microparticles prepared by cosolvent method was not affected by volume of organic solvent (1.5-3.0 ml) and drug loading (4-13%). An initial burst of approximately 10% followed by a 5-week sustained release phase was obtained. Microparticles with a size <50 microm released in a triphasic manner; an initial burst was followed by a slow release phase and then by a second burst.

  13. High pressure size exclusion chromatography (HPSEC) determination of dissolved organic matter molecular weight revisited: Accounting for changes in stationary phases, analytical standards, and isolation methods

    Science.gov (United States)

    McAdams, Brandon C.; Aiken, George R.; McKnight, Diane M.; Arnold, William A.; Chin, Yu-Ping

    2018-01-01

    We reassessed the molecular weight of dissolved organic matter (DOM) determined by high pressure size exclusion chromatography (HPSEC) using measurements made with different columns and various generations of polystyrenesulfonate (PSS) molecular weight standards. Molecular weight measurements made with a newer generation HPSEC column and PSS standards from more recent lots are roughly 200 to 400 Da lower than initial measurements made in the early 1990s. These updated numbers match DOM molecular weights measured by colligative methods and fall within a range of values calculated from hydroxyl radical kinetics. These changes suggest improved accuracy of HPSEC molecular weight measurements that we attribute to improved accuracy of PSS standards and changes in the column packing. We also isolated DOM from wetlands in the Prairie Pothole Region (PPR) using XAD-8, a cation exchange resin, and PPL, a styrene-divinylbenzene media, and observed little difference in molecular weight and specific UV absorbance at 280 nm (SUVA280) between the two solid phase extraction resins, suggesting they capture similar DOM moieties. PPR DOM also showed lower SUVA280 at similar weights compared to DOM isolates from a global range of environments, which we attribute to oxidized sulfur in PPR DOM that would increase molecular weight without affecting SUVA280.

  14. High Pressure Size Exclusion Chromatography (HPSEC) Determination of Dissolved Organic Matter Molecular Weight Revisited: Accounting for Changes in Stationary Phases, Analytical Standards, and Isolation Methods.

    Science.gov (United States)

    McAdams, Brandon C; Aiken, George R; McKnight, Diane M; Arnold, William A; Chin, Yu-Ping

    2018-01-16

    We reassessed the molecular weight of dissolved organic matter (DOM) determined by high pressure size exclusion chromatography (HPSEC) using measurements made with different columns and various generations of polystyrenesulfonate (PSS) molecular weight standards. Molecular weight measurements made with a newer generation HPSEC column and PSS standards from more recent lots are roughly 200 to 400 Da lower than initial measurements made in the early 1990s. These updated numbers match DOM molecular weights measured by colligative methods and fall within a range of values calculated from hydroxyl radical kinetics. These changes suggest improved accuracy of HPSEC molecular weight measurements that we attribute to improved accuracy of PSS standards and changes in the column packing. We also isolated DOM from wetlands in the Prairie Pothole Region (PPR) using XAD-8, a cation exchange resin, and PPL, a styrene-divinylbenzene media, and observed little difference in molecular weight and specific UV absorbance at 280 nm (SUVA 280 ) between the two solid phase extraction resins, suggesting they capture similar DOM moieties. PPR DOM also showed lower SUVA 280 at similar weights compared to DOM isolates from a global range of environments, which we attribute to oxidized sulfur in PPR DOM that would increase molecular weight without affecting SUVA 280 .

  15. Topical high molecular weight hyaluronan reduces radicular pain post laminectomy in a rat model.

    Science.gov (United States)

    Massie, Jennifer B; Schimizzi, Aimee L; Huang, Bill; Kim, Choll W; Garfin, Steven R; Akeson, Wayne H

    2005-01-01

    A controversy exists about the mechanism of causation of the post-laminectomy pain syndrome. Some believe that epidural scarring, and attendant spinal nerve and nerve root scarring and tethering to the disc or pedicle at the site of surgery contributes to post-laminectomy pain in such patients. However, clinical outcome studies on this question are inconclusive and the assertion remains controversial. Definitive studies to help resolve the question are needed. Previously our laboratory has reported on a preclinical post-laminectomy model that mimics the postoperative proliferative fibrotic response grossly, as well as by biochemical assessment of the collagen content within the spinal canal. The post-laminectomy fibrotic response was attenuated in that study by application of a topical antifibrotic (high molecular weight hyaluronan gel) or by insertion of an absorbable roofing barrier (0.2-mm-thick Macropore sheet material) over the laminectomy defect before wound closure. The question remains of relevance of the attenuation of the fibrotic response to post-laminectomy chronic pain syndromes. The purpose of this study is to evaluate the effect of therapeutic attenuation of proliferative scar within the spinal canal post laminectomy on the pain-related behavioral response in a preclinical rat model. An established L5-L6 rat laminectomy model with a unilateral L5-6 disc injury was employed to assess postoperative proliferative fibrosis of the L5 spinal nerves using quantitative biochemical hydroxyproline assessment of the collagen content in four experimental groups. These observations were correlated with gross descriptions of spinal nerve scarring or tethering. Associated manifestations of a sensory pain-related response in the L5 spinal nerve receptor area of the hind paws was studied using standard tactile allodynia assessment with the von Frey hair technique. The tactile allodynia findings were supplemented by weekly descriptors of behavioral pain manifestations

  16. Novel Synthesis of Core-Shell Silica Nanoparticles for the Capture of Low Molecular Weight Proteins and Peptides

    Directory of Open Access Journals (Sweden)

    Sergio G. Hernandez-Leon

    2017-10-01

    Full Text Available Silica nanoparticles were functionalized with immobilized molecular bait, Cibacron Blue, and a porous polymeric bis-acrylamide shell. These nanoparticles represent a new alternative to capture low molecular weight (LMW proteins/peptides, that might be potential biomarkers. Functionalized core-shell silica nanoparticles (FCSNP presented a size distribution of 243.9 ± 11.6 nm and an estimated surface charge of −38.1 ± 0.9 mV. The successful attachment of compounds at every stage of synthesis was evidenced by ATR-FTIR. The capture of model peptides was determined by mass spectrometry, indicating that only the peptide with a long sequence of hydrophobic amino acids (alpha zein 34-mer interacted with the molecular bait. FCSNP excluded the high molecular weight protein (HMW, BSA, and captured LMW proteins (myoglobin and aprotinin, as evidenced by SDS-PAGE. Functionalization of nanoparticles with Cibacron Blue was crucial to capture these molecules. FCSNP were stable after twelve months of storage and maintained a capacity of 3.1–3.4 µg/mg.

  17. Low-molecular-weight heparins for managing vaso-occlusive crises in people with sickle cell disease.

    Science.gov (United States)

    van Zuuren, Esther J; Fedorowicz, Zbys

    2015-12-18

    Sickle cell disease is one of the most common and severe genetic disorders in the world. It can be broadly divided into two distinct clinical phenotypes characterized by either haemolysis or vaso-occlusion. Pain is the most prominent symptom of vaso-occlusion, and hypercoagulability is a well-established pathogenic phenomenon in people with sickle cell disease. Low-molecular-weight heparins might control this hypercoagulable state through their anticoagulant effect. This is an update of a previously published version of this review. To assess the effects of low-molecular-weight heparins for managing vaso-occlusive crises in people with sickle cell disease. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register comprising references identified from comprehensive electronic database searches. We also searched abstract books of conference proceedings and several online trials registries for ongoing trials.Date of the last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register: 28 September 2015. Randomised controlled clinical trials and controlled clinical trials that assessed the effects of low-molecular-weight heparins in the management of vaso-occlusive crises in people with sickle cell disease. Study selection, data extraction, assessment of risk of bias and analyses were carried out independently by the two review authors. Two studies comprising 287 participants were included. One study (with an overall unclear to high risk of bias) involved 253 participants and the quality of the evidence for most outcomes was very low. This study, reported that pain severity at day two and day three was lower in the tinzaparin group than in the placebo group (P quality of evidence rated very low. The most important reasons for downgrading the quality of evidence were serious risk of bias and imprecision (due to low sample size or low occurrence of events). Based on the results

  18. Low molecular weight thiols and thioredoxins are important players in Hg(II) resistance in Thermus thermophilus HB27.

    Science.gov (United States)

    Norambuena, J; Wang, Y; Hanson, T; Boyd, J M; Barkay, T

    2017-11-17

    Mercury (Hg), one of the most toxic and widely distributed heavy metals, has a high affinity for thiol groups. Thiol groups reduce and sequester Hg. Therefore, low molecular weight and protein thiols may be important cell components used in Hg resistance. To date, the role of low molecular weight thiols in Hg-detoxification remains understudied. The mercury resistance ( mer ) operon of Thermus thermophilus suggests an evolutionary link between Hg(II) resistance and low molecular weight thiol metabolism. This mer operon encodes for an enzyme involved in methionine biosynthesis, Oah. Challenge with Hg(II) resulted in increased expression of genes involved in the biosynthesis of multiple low molecular weight thiols (cysteine, homocysteine, and bacillithiol), as well as the thioredoxin system. Phenotypic analysis of gene replacement mutants indicated that Oah contributes to Hg resistance under sulfur limiting conditions, and strains lacking bacillithiol and/or thioredoxins are more sensitive to Hg(II) than the wild type. Growth in presence of either a thiol oxidizing agent or a thiol alkylating agent increased sensitivity to Hg(II). Furthermore, exposure to 3 μM Hg(II) consumed all intracellular reduced bacillithiol and cysteine. Database searches indicate that oah2 is present in all Thermus spp. mer operons. The presence of a thiol related gene was also detected in some alphaprotobacterial mer operons, in which a glutathione reductase gene was present, supporting the role of thiols in Hg(II) detoxification. These results have led to a working model in which LMW thiols act as Hg(II) buffering agents while Hg is reduced by MerA. Importance The survival of microorganisms in presence of toxic metals is central to life's sustainability. The affinity of thiol groups to toxic heavy metals drives microbe-metal interactions and modulate metal toxicity. Mercury detoxification ( mer ) genes likely originated early in microbial evolution among geothermal environments. Little is

  19. Ribonucleic acid from the higher plant Matthiola incana. Molecular weight measurements and DNA-RNA hybridisation studies.

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    Grierson, D; Hemleben, V

    1977-04-04

    The percentage of DNA from the crucifer Matthiola incana coding for different types of RNA was measured by filter saturation hybridisation experiments using RNA labelled in vivo. In addition, the melting curves of the various DNA - RNA hybrids formed and the buoyant densities of the DNA sequences complementary to different types of RNA were measured. 1. The RNA preparations used were 25, 18, and 5 S rRNA and 4 S RNA, purified by gel electrophoresis, and poly(A)-containing RNA purified by oligo-(dT)-cellulose chromatography. The molecular weights of the 25 S and 18 S rRNAs, calculated from the mobility in formamide-acrylamide gels relative to Escherichia coli RNA, are 1.25 - 10(6) and 0.64 - 10(6). The rRNA precursor has a molecular weight of approx. 2.1 - 10(6) and the average molecular weight of the poly(A)-containing RNA from both cotyledons and roots is 4 - 10(5). 2. The percentage of the genome, calculated on the basis of double-stranded DNA, coding for these RNAs and the estimated number of genes per haploid DNA amount are approximately 0.46% and 1100 for 25 S plus 18 S rRNA, 0.032% and 3600 for 5 S rRNA and 0.072% and 13 000 for 4 S RNA. In filter hybridisation experiments very little hybridisation of poly(A)-containing RNA was found. A rapidly-hybridising component is attributed to small amounts of contaminating rRNA. 3. M. incana DNA has a main band at 1.697 g - ml-1 in CsCl and a satellite constituting approximately 3% of the DNA, at 1.708 g - ml-1 - 25 and 18 S rRNA hybridise to DNA with a buoyant density of 1.701--2 g - ml-1. The buoyant density of 5 S DNA is slightly less at 1.700--1 g - ml-1. 4. S RNA hybridises to at least two separate regions, one within the main-band DNA and a second lighter component. None of the RNAs tested hybridised to the satellite DNA. The Tm of the DNA - RNA hybrids in 1 X SSC is 89 degrees C for 25 S rRNA, 85 degrees C for 5 S rRNA and 82 degrees C for 4 S RNA. 4. 5 and 4 S RNA preparations contain fragments which hybridise

  20. Nanoscale Morphology to Macroscopic Performance in Ultra High Molecular Weight Polyethylene Fibers

    Science.gov (United States)

    McDaniel, Preston B.

    Ultra high molecular weight polyethylene (UHMWPE) fibers are increasingly used in high -performance applications where strength, stiffness, and the ability to dissipate energy are of critical importance. Despite their use in a variety of applications, the influence of morphological features at the meso/nanoscale on the macroscopic performance of the fibers has not been well understood. There is particular interest in gaining a better understanding of the nanoscale structure-property relationships in UHMWPE fibers used in ballistics applications. In order to accurately model and predict failure in the fiber, a more complete understanding of the complex load pathways that dictate the ways in which load is transferred through the fiber, across interfaces and length scales is required. The goal of the work discussed herein is to identify key meso/nanostructural features evolved in high performance fibers and determine how these features influence the performance of the fiber through a variety of different loading mechanisms. The important structural features in high-performance UHMWPE fibers are first identified through examination of the meso/nanostructure of a series of fibers with different processing conditions. This is achieved primarily through the use of wide-angle x-ray diffraction (WAXD) and atomic force microscopy (AFM). Analysis of AFM images and WAXD data allows identification and quantifications of important structural features at these length scales. Key meso/nanostructural features are then examined with respect to their influence on the transverse compression behavior of single fibers. Through post-mortem AFM analysis of samples at incremental compressive strains, the evolution of damage is examined and compared with macroscopic fiber mechanical response. It was found that collapse of mesoscale voids, followed by nanoscale fibrillation and reorganization of a fibrillar network has a significant influence on the mechanical response of the fiber. Through