Development of haplotype-specific molecular markers for the low-molecular-weight glutenin subunits

USDA-ARS?s Scientific Manuscript database

Low-molecular-weight glutenin subunits (LMW-GSs) are one of the major components of gluten and their allelic variation has been widely associated with numerous wheat end-use quality parameters. These proteins are encoded by multigene families located at the orthologous Glu-3 loci (Glu-A3, Glu-B3 and...

Bacterial attack on phenolic ethers. Purification and characterization of the components of the meta O-dealkylase of Pseudomonas fluorescens Tp.

PubMed

Pietrowski, R A; Cartwright, N J

1977-01-01

The meta O-dealkylase of Pseudomonas fluorescens Tp has been resolved into two protein components, neither of which is a cytochrome. The substrate binding terminal oxidase has been purified and shown to be a non-haem iron protein of approximate molecular weight 118,000, consisting of two seemingly identical subunits, each of molecular weight 55,000. Binding of substrate by the terminal oxidase has been established by difference spectroscopy. The amino acid composition of the protein has also been determined. The NADH-dependent reductase of the system has been partly purified and appears to have a molecular weight of 80,000. The similarity between this and other bacterial O-dealkylases is discussed.

Method for creating an aeronautic sound shield having gas distributors arranged on the engines, wings, and nose of an aircraft

NASA Technical Reports Server (NTRS)

Corda, Stephen (Inventor); Smith, Mark Stephen (Inventor); Myre, David Daniel (Inventor)

2008-01-01

The present invention blocks and/or attenuates the upstream travel of acoustic disturbances or sound waves from a flight vehicle or components of a flight vehicle traveling at subsonic speed using a local injection of a high molecular weight gas. Additional benefit may also be obtained by lowering the temperature of the gas. Preferably, the invention has a means of distributing the high molecular weight gas from the nose, wing, component, or other structure of the flight vehicle into the upstream or surrounding air flow. Two techniques for distribution are direct gas injection and sublimation of the high molecular weight solid material from the vehicle surface. The high molecular weight and low temperature of the gas significantly decreases the local speed of sound such that a localized region of supersonic flow and possibly shock waves are formed, preventing the upstream travel of sound waves from the flight vehicle.

Characterization of secondary organic aerosol from photo-oxidation of gasoline exhaust and specific sources of major components.

PubMed

Ma, Pengkun; Zhang, Peng; Shu, Jinian; Yang, Bo; Zhang, Haixu

2018-01-01

To further explore the composition and distribution of secondary organic aerosol (SOA) components from the photo-oxidation of light aromatic precursors (toluene, m-xylene, and 1,3,5-trimethylbenzene (1,3,5-TMB)) and idling gasoline exhaust, a vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS) was employed. Peaks of the molecular ions of the SOA components with minimum molecular fragmentation were clearly observed from the mass spectra of SOA, through the application of soft ionization methods in VUV-PIMS. The experiments comparing the exhaust-SOA and light aromatic mixture-SOA showed that the observed distributions of almost all the predominant cluster ions in the exhaust-SOA were similar to that of the mixture-SOA. Based on the characterization experiments of SOA formed from individual light aromatic precursors, the SOA components with molecular weights of 98 and 110 amu observed in the exhaust-SOA resulted from the photo-oxidation of toluene and m-xylene; the components with a molecular weight of 124 amu were derived mainly from m-xylene; and the components with molecular weights of 100, 112, 128, 138, and 156 amu were mainly derived from 1,3,5-TMB. These results suggest that C 7 -C 9 light aromatic hydrocarbons are significant SOA precursors and that major SOA components originate from gasoline exhaust. Additionally, some new light aromatic hydrocarbon-SOA components were observed for the first time using VUV-PIMS. The corresponding reaction mechanisms were also proposed in this study to enrich the knowledge base of the formation mechanisms of light aromatic hydrocarbon-SOA compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

Low molecular weight components in an aquatic humic substance as characterized by membrane dialysis and orbitrap mass spectrometry.

PubMed

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 <600 Da in a complex mixture, such as SRFA. The most intense 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.

Improvement of liquid stored boar semen quality by removing low molecular weight proteins and supplementation with α-tocopherol.

PubMed

Zakošek Pipan, M; Mrkun, J; Nemec Svete, A; Zrimšek, P

2017-11-01

Seminal plasma contains low-molecular weight components that can exert a harmful effect on sperm function. We have evaluated the effects of removing low-molecular weight components from seminal plasma and adding α-tocopherol on boar semen quality after 72h of liquid storage. Semen was evaluated on the basis of motility, morphology, acrosome integrity, plasma membrane modifications, mitochondrial activity, DNA fragmentation and lipid peroxidation. Thiobarbituric acid reactive substances (TBARS), 8-isoprostane, and antioxidant status (total antioxidant capacity (TAC) and superoxide dismutase activity (SOD)) were measured in seminal plasma. Removal of low-molecular weight components from seminal plasma, together with the addition of α-tocopherol, kept the lipid peroxidation and mitochondrial activity and DNA fragmentation at the same level as in native semen samples. Dialysing semen and adding 200μM of α-tocopherol led to higher progressive motility, a higher proportion of morphologically normal spermatozoa and a significantly lower level of acrosomal reacted spermatozoa compared to non-dialyzed semen samples after 72h of storage. In conclusion, liquid stored boar semen was better preserved, and oxidative stress in the semen was reduced when semen was dialyzed and α-tocopherol was added prior to storage. Copyright © 2017 Elsevier B.V. All rights reserved.

Optoelectronic devices incorporating fluoropolymer compositions for protection

DOEpatents

Chen, Xuming; Chum, Pak-Wing S.; Howard, Kevin E.; Lopez, Leonardo C.; Sumner, William C.; Wu, Shaofu

2015-12-22

The fluoropolymer compositions of the present invention generally incorporate ingredients comprising one or more fluoropolymers, an ultraviolet light protection component (hereinafter UV protection component), and optionally one or more additional ingredients if desired. The UV protection component includes a combination of at least one hindered tertiary amine (HTA) compound having a certain structure and a weight average molecular weight of at least 1000. This tertiary amine is used in combination with at least one organic, UV light absorbing compound (UVLA compound) having a weight average molecular weight greater than 500. When the HTA compound and the UVLA compound are selected according to principles of the present invention, the UV protection component provides fluoropolymer compositions with significantly improved weatherability characteristics for protecting underlying materials, features, structures, components, and/or the like. In particular, fluoropolymer compositions incorporating the UV protection component of the present invention have unexpectedly improved ability to resist blackening, coloration, or other de gradation that may be caused by UV exposure. As a consequence, devices protected by these compositions would be expected to have dramatically improved service life. The compositions have a wide range of uses but are particularly useful for forming protective layers in optoelectronic devices.

Loss of heterocyclic amine mutagens by insoluble hemicellulose fiber and high-molecular-weight soluble polyphenolics of coffee.

PubMed

Kato, T; Takahashi, S; Kikugawa, K

1991-01-01

The presence of 2 kinds of components in brewed and instant coffee that could remove and destroy heterocyclic amine mutagens was demonstrated. The component that could remove the mutagens was insoluble fiber composed of hemicellulose. The fiber could tightly adsorb the mutagens Trp-P-1, Trp-P-2, Glu-P-1 and A alpha C, and those generated in roasted coffee beans. The component that could destroy the mutagens was high-molecular-weight soluble polyphenolics. They might be converted into quinone derivatives in the presence of molecular oxygen. The quinone derivatives might destroy the mutagens. The fibers and the polyphenolics in one cup of brewed or instant coffee had the capacity to remove and destroy a substantial amount of the mutagens in pyrolysates of foodstuffs.

Biochemical Composition of Dissolved Organic Matter Released During Experimental Diatom Blooms

NASA Technical Reports Server (NTRS)

Mannino, Antonio; Harvey, H. Rodger

2002-01-01

An axenic culture of Skeletonema costatum was grown to late-log phase to examine the molecular weight distribution and the biochemical composition of high molecular weight dissolved organic matter released in the absence of actively growing bacteria. A second culture was grown in a 5 m(exp 3) mesocosm and placed in darkness for a period of 51 days to examine the impact of phytoplankton bloom dynamics and microbial decomposition on dissolved (DOM) and particulate organic matter (POM) composition. DOM was separated using tangential-flow ultrafiltration into three nominal size fractions: LDOM (less than 1 kDa DOM), HDOM (1-30 kDa) and VHDOM (30 kDa-0.2 micron) and characterized. Both axenic and mesocosm diatom blooms released 28-33% of net primary production as dissolved organic carbon (DOC). In the axenic culture, HDOM and LDOM each comprised about half of the diatom-released DOC with less than l% as VHDOM. Diatoms from both experiments released carbohydrate-rich high molecular weight DOM. Much of the axenic diatom-released high molecular weight DOC could be chemically characterized (61% of HDOM and 78% of VHDOM) with carbohydrates as the primary component (45% of HDOM and 55% of VHDOM). Substantial amounts of hydrolyzable amino acids (16% of HDOM and 22% of VHDOM) and small amounts of lipids (less than 1%) were also released. Proportions of recognizable biochemical components in DOM produced in the mesocosm bloom were lower compared to the axenic culture. The presence of bacterial fatty acids and peptidoglycan-derived D-amino acids within high molecular weight fractions from the mesocosm bloom revealed that bacteria contributed a variety of macromolecules to DOM during the growth and decay of the diatom bloom. Release of significant amounts of DOC by diatoms demonstrates that DOM excretion is an important component of phytoplankton primary production. Similarities in high molecular weight DOM composition in marine waters and diatom cultures highlight the importance of phytoplankton to DOM composition in the ocean.

Biological and structural analyses of bovine heparin fractions of intermediate and high molecular weight.

PubMed

Nogueira, Alexsandro V; Drehmer, Daiana L; Iacomini, Marcello; Sassaki, Guilherme L; Cipriani, Thales R

2017-02-10

Low molecular weight heparin, which is generally obtained by chemical and enzymatic depolymerization of unfractionated heparin, has high bioavailability and can be subcutaneously injected. The aim of the present investigation was to fractionate bovine heparin using a physical method (ultrafiltration through a 10kDa cut-off membrane), avoiding structural modifications that can be caused by chemical or enzymatic treatments. Two fractions with different molecular weights were obtained: the first had an intermediate molecular weight (B-IMWH; Mn=9587Da) and the other had a high molecular weight (B-HMWH; 22,396Da). B-IMWH and B-HMWH have anticoagulant activity of 103 and 154IU/mg respectively, which could be inhibited by protamine. Both fractions inhibited α-thrombin and factor Xa in vitro and showed antithrombotic effect in vivo. Moreover, ex vivo aPTT assay demonstrated that B-IMWH is absorbed by subcutaneous route. The results showed that ultrafiltration can be used to obtain two bovine heparin fractions, which differ on their molecular weights, structural components, anticoagulant potency, and administration routes. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

PubMed

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.

Determination of molecular weight distributions in native and pretreated wood.

PubMed

Leskinen, Timo; Kelley, Stephen S; Argyropoulos, Dimitris S

2015-03-30

The analysis of native wood components by size-exclusion chromatography (SEC) is challenging. Isolation, derivatization and solubilization of wood polymers is required prior to the analysis. The present approach allowed the determination of molecular weight distributions of the carbohydrates and of lignin in native and processed woods, without preparative component isolation steps. For the first time a component selective SEC analysis of sawdust preparations was made possible by the combination of two selective derivatization methods, namely; ionic liquid assisted benzoylation of the carbohydrate fraction and acetobromination of the lignin in acetic acid media. These were optimized for wood samples. The developed method was thus used to examine changes in softwood samples after degradative mechanical and/or chemical treatments, such as ball milling, steam explosion, green liquor pulping, and chemical oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The methodology can also be applied to examine changes in molecular weight and lignin-carbohydrate linkages that occur during wood-based biorefinery operations, such as pretreatments, and enzymatic saccharification. Copyright © 2014 Elsevier Ltd. All rights reserved.

Characteristics and bioactivities of different molecular weight polysaccharides from camellia seed cake.

PubMed

Xu, Zhou; Li, Xu; Feng, Shiling; Liu, Jing; Zhou, Lijun; Yuan, Ming; Ding, Chunbang

2016-10-01

Four polysaccharides, namely COP-1, COP-2, COP-3 and COP-4, were ultrafiltrated from crud Camellia oleifera seed cake polysaccharides (COP-c), purified, and characterized, including the determination of antioxidant and antiproliferative activities. Their molecular weights were 7.9, 36, 83 and 225kDa, respectively. All COPs showed the similar FT-IR spectrums, but significant differentials in monosaccharide components. COP-2 exhibited the highest radical scavenging abilities. COP-1 has the strongest metal chelating capabilities. Although with higher molecular weight, COP-4 showed the poorest antioxidant abilities. These results suggested appreciate molecular weight COP possessed a better antioxidant activities. Additionally, all COPs had non-significant antiproliferative abilities in HaLa and HepG2 cells. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaporative purification to produce highly monodisperse polymers: Application to polystyrene for n =3 -13 and quantification of Tg from oligomer to polymer

NASA Astrophysics Data System (ADS)

Zhu, S.; Chai, Y.; Forrest, J. A.

2017-07-01

We demonstrate the use of selective thermal evaporation to separate and purify small molecular weight polymers into highly monodisperse polymers over an extended range of polymerization index. By exploiting the calculated dependence of polymer vapor pressure on polymerization index N and temperature T , we can isolate individual components (N -mers) of an initially polydisperse mixture. To demonstrate this ability, we consider polystyrene samples of Mw=600 g/mol and Mw=890 g/mol with narrow molecular weight distributions, as well as a Mw=1200 g/mol sample with a broader distribution. In each case we are able to separate the sample into milligram quantities of many different components. Using this technique, we have been able to isolate N -mers from 3 to 13. We use differential scanning calorimetry to measure the Tg values of these components, and find that the components have the same Tg values independent of the Mw or polydispersity of the sample they originate from. We find that even initially narrow molecular weight distributions have many different components whose Tg values can differ by more than 50 K. Calculations suggest the isolated components have Mw/Mn values less than 1.001 and through a second iteration of the process could become as low as 1.000 003. The measured Tg values for the N -mers as well as large N polymers are well described by a simple relation derived from the Fox equation for the Tg of mixtures.

Indirect measurement of diluents in a multi-component natural gas

DOEpatents

Morrow, Thomas B.; Owen, Thomas E.

2006-03-07

A method of indirectly measuring the diluent (nitrogen and carbon dioxide) concentrations in a natural gas mixture. The molecular weight of the gas is modeled as a function of the speed of sound in the gas, the diluent concentrations in the gas, and constant values, resulting in a model equation. A set of reference gas mixtures with known molecular weights and diluent concentrations is used to calculate the constant values. For the gas in question, if the speed of sound in the gas is measured at three states, the three resulting expressions of molecular weight can be solved for the nitrogen and carbon dioxide concentrations in the gas mixture.

Rigid zeolite containing polyurethane foams

DOEpatents

Frost, Charles B.

1985-01-01

A closed cell rigid polyurethane foam has been prepared which contains up to about 60% by weight of molecular sieves capable of sorbing molecules with effective critical diameters of up to about 10 .ANG.. The molecular sieve component of the foam can be preloaded with catalysts or with reactive compounds that can be released upon activation of the foam to control and complete crosslinking after the foam is formed. The foam can also be loaded with water or other flame-retarding agents, after completion. Up to about 50% of the weight of the isocyanate component of the foam can be replaced by polyimide resin precursors for incorporation into the final polymeric network.

Rigid zeolite containing polyurethane foams

DOEpatents

Frost, C.B.

1984-05-18

A closed cell rigid polyurethane foam has been prepared which contains up to about 60% by weight of molecular sieves capable of sorbing molecules with effective critical diameters of up to about 10 A. The molecular sieve component of the foam can be preloaded with catalysts or with reactive compounds that can be released upon activation of the foam to control and complete crosslinking after the foam is formed. The foam can also be loaded with water or other flame-retarding agents, after completion. Up to about 50% of the weight of the isocyanate component of the foam can be replaced by polyimide resin precursors for incorporation into the final polymeric network.

Removal of humic acid using TiO2 photocatalytic process--fractionation and molecular weight characterisation studies.

PubMed

Liu, Sanly; Lim, May; Fabris, Rolando; Chow, Christopher; Chiang, Ken; Drikas, Mary; Amal, Rose

2008-05-01

The photocatalytic removal of humic acid (HA) using TiO2 under UVA irradiation was examined by monitoring changes in the UV(254) absorbance, dissolved organic carbon (DOC) concentration, apparent molecular weight distribution, and trihalomethane formation potentials (THMFPs) over treatment time. A resin fractionation technique in which the samples were fractionated into four components: very hydrophobic acids (VHA), slightly hydrophobic acids, hydrophilic charged (CHA) and hydrophilic neutral (NEU) was also employed to elucidate the changes in the chemical nature of the HA components during treatment. The UVA/TiO2 process was found to be effective in removing more than 80% DOC and 90% UV(254) absorbance. The THMFPs of samples were decreased to below 20 microg l(-1) after treatments, which demonstrate the potential to meet increasingly stringent regulatory level of trihalomethanes in water. Resin fractionation analysis showed that the VHA fraction was decreased considerably as a result of photocatalytic treatments, forming CHA intermediates which were further degraded with increased irradiation time. The NEU fraction, which comprised of non-UV-absorbing low molecular weight compounds, was found to be the most persistent component.

Sequence control of phase separation and dewetting in PS/PVME blend thin films by changing molecular weight of PS.

PubMed

Xia, Tian; Qin, Yaping; Huang, Yajiang; Huang, Ting; Xu, Jianhui; Li, Youbing

2016-11-28

The morphology evolution mechanism of polystyrene (PS)/poly (vinyl methyl ether) (PVME) blend thin films with different PS molecular weights (M w ) was studied. It was found that the morphology evolution was closely related to the molecular weight asymmetry between PS and PVME. In the film where M w (PS) ≈ M w (PVME), dewetting happened at the interface between the bottom layer and substrate after SD phase separation. While in the film where M w (PS) > M w (PVME), dewetting happened at the interface between the middle PS/PVME blend layer and bottom PVME layer near the substrate prior to phase separation. The different sequences of phase separation and dewetting and different interface for dewetting occurrence were studied by regarding the competitive effects of viscoelasticity contrast between polymer components and preferential wetting between PVME and the substrate. The viscoelastic nature of the PS component played a crucial role in the sequence of phase separation and dewetting.

Comparative proteomic analysis of male and female venoms from the Cuban scorpion Rhopalurus junceus.

PubMed

Rodríguez-Ravelo, Rodolfo; Batista, Cesar V F; Coronas, Fredy I V; Zamudio, Fernando Z; Hernández-Orihuela, Lorena; Espinosa-López, Georgina; Ruiz-Urquiola, Ariel; Possani, Lourival D

2015-12-01

A complete mass spectrometry analysis of venom components from male and female scorpions of the species Rhophalurus junceus of Cuba is reported. In the order of 200 individual molecular masses were identified in both venoms, from which 63 are identical in male and females genders. It means that a significant difference of venom components exists between individuals of different sexes, but the most abundant components are present in both sexes. The relative abundance of identical components is different among the genders. Three well defined groups of different peptides were separated and identified. The first group corresponds to peptides with molecular masses of 1000-2000 Da; the second to peptides with 3500-4500 Da molecular weight, and the third with 6500-8000 Da molecular weights. A total of 86 peptides rich in disulfide bridges were found in the venoms, 27 with three disulfide bridges and 59 with four disulfide bridges. LC-MS/MS analysis allowed the identification and amino acid sequence determination of 31 novel peptides in male venom. Two new putative K(+)-channel peptides were sequences by Edman degradation. They contain 37 amino acid residues, packed by three disulfide bridges and were assigned the systematic numbers: α-KTx 1.18 and α-KTx 2.15. Copyright © 2015 Elsevier Ltd. All rights reserved.

Physical characterization of polyethylene glycols by thermal analytical technique and the effect of humidity and molecular weight.

PubMed

Majumdar, R; Alexander, K S; Riga, A T

2010-05-01

Polyethylene glycols (PEGs) are well known as excipients in tablet dosage formulations. PEGs are generally known to be inert and have very few interactions with other components in the solid dosage forms. However, the physical nature of PEGs and how they affect the disintegration of tablets is not very well understood for the different molecular weights of PEGs. The knowledge of the effect of molecular weight of PEGs on their physical properties and the effect of humidity on the physical properties of PEGs are important parameters for the choice of a PEG to be acceptable as an excipient in pharmaceutical formulations. This study was done to determine the precision of the DSC physical properties for a wide range of PEGs with varying molecular weights from 194 to 23000 daltons. Nine different molecular weights of PEGs were examined in a DSC controlled Heat-Cool-Heat-Cool-Heat (HCHCH) cycle and the observed reproducible values of melting temperature, heat of fusion, crystallization temperature and the heat of crystallization were compared with values obtained from the literature and the observed percent crystallinity was again cross-checked by X-ray Diffraction (XRD) studies. The comparison values indicated acceptable precision. This study was also done to check the effect of humidity on the DSC physical properties for the entire range of PEGs. The results indicated that humidity probably has a higher effect on the physical properties of the low molecular weight PEGs as compared to the high molecular weight PEGs.

Environmentally stable polymers and coatings for space application: CH-5, supplement 10

NASA Technical Reports Server (NTRS)

Sykes, G.

1986-01-01

High molecular weight, randomly coupled poly(imide siloxane) soluble block copolymers were synthesized from bis(amino propyl) polydimethylsiloxane equilibrates of various molecular weights, aromatic metalinked diamines, and 3,3'-4,4'-benzophenone tetracarboxylic dianhydride (BTDA). Two synthetic procedures were successfully used to synthesize the poly(amic acid siloxane) intermediates. For both synthetic procedures, a cosolvent system was employed to achieve complete solvation of all components throughout the polymerization. Physical property characterization is continuing.

Cytotoxicity associated with electrospun polyvinyl alcohol.

PubMed

Pathan, Saif G; Fitzgerald, Lisa M; Ali, Syed M; Damrauer, Scott M; Bide, Martin J; Nelson, David W; Ferran, Christiane; Phaneuf, Tina M; Phaneuf, Matthew D

2015-11-01

Polyvinyl alcohol (PVA) is a synthetic, water-soluble polymer, with applications in industries ranging from textiles to biomedical devices. Research on electrospinning of PVA has been targeted toward optimizing or finding novel applications in the biomedical field. However, the effects of electrospinning on PVA biocompatibility have not been thoroughly evaluated. In this study, the cytotoxicity of electrospun PVA (nPVA) which was not crosslinked after electrospinning was assessed. PVA polymers of several molecular weights were dissolved in distilled water and electrospun using the same parameters. Electrospun PVA materials with varying molecular weights were then dissolved in tissue culture medium and directly compared against solutions of nonelectrospun PVA polymer in human coronary artery smooth muscle cells and human coronary artery endothelial cells cultures. All nPVA solutions were cytotoxic at a threshold molar concentration that correlated with the molecular weight of the starting PVA polymer. In contrast, none of the nonelectrospun PVA solutions caused any cytotoxicity, regardless of their concentration in the cell culture. Evaluation of the nPVA material by differential scanning calorimetry confirmed that polymer degradation had occurred after electrospinning. To elucidate the identity of the nPVA component that caused cytotoxicity, nPVA materials were dissolved, fractionated using size exclusion columns, and the different fractions were added to HCASMC and human coronary artery endothelial cells cultures. These studies indicated that the cytotoxic component of the different nPVA solutions were present in the low-molecular-weight fraction. Additionally, the amount of PVA present in the 3-10 kg/mol fraction was approximately sixfold greater than that in the nonelectrospun samples. In conclusion, electrospinning of PVA resulted in small-molecular-weight fractions that were cytotoxic to cells. This result demonstrates that biocompatibility of electrospun biodegradable polymers should not be assumed on the basis of success of their nonelectrospun predecessors. © 2015 Wiley Periodicals, Inc.

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

PubMed

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.

Toughening mechanism in elastomer-modified epoxy resins, part 2

NASA Technical Reports Server (NTRS)

Yee, A. F.; Pearson, R. A.

1984-01-01

The role of matrix ductility on the toughenability and toughening mechanism of elastomer-modified DGEBRA epoxies was investigated. Matrix ductility was varied by using epoxide resins of varying epoxide monomer molecular weights. These epoxide resins were cured using 4,4' diaminodiphenyl sulfone (DDS) and, in some cases, modified with 10% HYCAR(r)CTBN 1300X8. Fracture roughness values for the neat epoxies were found to be almost independent on the monomer molecular weight of the epoxide resin used. However, it was found that the fracture toughness of the elastomer-modified epoxies was very dependent upon the epoxide monomer molecular weight. Tensile dilatometry indicated that the toughening mechanism, when present, is similar to the mechanisms found for the piperidine cured epoxies in Part 1. SEM and OM corroborate this finding. Dynamic mechanical studies were conducted to shed light on the toughenability of the epoxies. The time-dependent small strain behavior of these epoxies were separated into their bulk and shear components. The bulk component is related to brittle fracture, whereas the shear component is related to yielding. It can be shown that the rates of shear and bulk strain energy buildup for a given stress are uniquely determined by the values of Poisson's ratio, nu. It was found that nu increases as the monomer molecular weight of the epoxide resin used increases. This increase in nu can be associated with the low temperature beta relaxation. The effect of increasing cross-link density is to shift the beta relaxation to higher temperatures and to decrease the magnitude of the beta relaxation. Thus, increasing cross-link density decreases nu and increases the tendency towards brittle fracture.

The effect of serum on the secretion of radiolabeled mucous macromolecules into the lumen of the cat trachea

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

Peatfield, A.C.; Hall, R.L.; Richardson, P.S.

1982-02-01

We studied the effect of placing serum within a segment of trachea on secretion into its lumen in the cat. A segment of cervical trachea was isolated from the rest of the airway in situ. Secretions were radiolabeled biosynthetically by the administration of two radiolabeled precursors: (35S)sodium sulphate and (3H)glucose. Autologous serum placed in the segment at a dilution of 1 in 8 increased the output of radiolabeled macromolecules: (35S) by 80% and (3H) by 159% (p less than 0.001). At a dilution of 1 in 24, serum still increased the output of both isotopes. At dilutions of 1 inmore » 48 and 1 in 80 the increases were significant for (35S) but not for (3H). Heating the serum to 90 degrees C diminished its effects. Fractionating the serum by dialysis and gel filtration showed that the components of molecular weight less than about 13,000 daltons had no effect on secretion, whereas three higher molecular weight fractions all increased secretion. Two alien proteins (horseradish peroxidase and bovine serum albumin) stimulated secretion but a large molecular weight carbohydrate (carboxymethyl cellulose) did not. Atropine and propranolol, at doses that greatly reduced the effect of parasympathetic and sympathetic nerve activity, did not diminish the effects of serum, which therefore appeared to be independent of nerve activity. Gel filtration of the secretions elicited by serum showed that the predominant component was excluded even by Sepharose CL-2B and thus had a high molecular weight. We conclude that there are several components of serum that promote the secretion of mucus glycoproteins into the cat trachea. The relevance of these findings to diseases of human airways is considered.« less

Histidinoalanine, a naturally occurring cross-link derived from phosphoserine and histidine residues in mineral-binding phosphoproteins.

PubMed

Marsh, M E

1986-05-06

Native mineral-containing phosphoprotein particles were isolated from the Heterodont bivalve Macrocallista nimbosa. The native particles are discrete structures about 40 nm in diameter which migrate as a single band during electrophoresis in agarose gels. Removal of the mineral component with ethylenediaminetetraacetic acid dissociates the native protein into nonidentical subunits. The lower molecular weight subunits, representing 8% of the total protein, were obtained by differential centrifugation. The native protein is characterized by a high content of aspartic acid, phosphoserine, phosphothreonine, histidine, and the bifunctional cross-linking residue histidinoalanine. The low molecular weight subunits have the same amino acid composition except for a reduction in histidinoalanine and a corresponding increase in phosphoserine and histidine residues, demonstrating that the alanine portion of the cross-link is derived from phosphoserine residues. Ion-exchange chromatography and molecular sieve chromatography show that the low molecular weight subunits have a similar charge density but differ in molecular weight, and the relative mobilities of the subunits on agarose gels indicate that they are polymers of a single phosphoprotein molecule. The minimum molecular weight of the monomer is about 140 000 on the basis of the amino acid composition. The high molecular weight subunits are rich in histidinoalanine and too large to be resolved by either molecular sieve chromatography or gel electrophoresis. On the basis of the ultrastructural, electrophoretic, chromatographic, and compositional evidence, native phosphoprotein particles are composed of subunits ionically cross-linked via divalent cations. These subunits are variable molecular weight aggregates of a single phosphoprotein molecule covalently cross-linked via histidinoalanine residues. Evidence for a nonenzymatic cross-linking mechanism is discussed.

[Low-molecular-weight autoregulatory factors in bacteria Thioalkalivibrio versutus and Thioalkalimicrobium aerophilum].

PubMed

Loĭko, N G; Kozlova, A N; Osipov, G A; El'-Registan, G I

2002-01-01

The haloalkaliphilic, lithoautotrophic, sulfur-oxidizing gram-negative bacteria Thioalkalivibrio versutus and Thioalkalimicrobium aerophilum were found to possess a special system for the autoregulation of their growth. The system includes the extracellular autoinducers of anabiosis (the d1 factor) and autolysis (the d2 factor). The principal components of the d1 factor are alkylhydroxybenzenes. The principal components of the d2 factor are free unsaturated fatty acids dominated by oleic acid isomers. Like the respective autoregulators of neutrophilic bacteria, the d1 factor of haloalkaliphilic bacteria presumably controls their growth and transition to a anabiotic state, while the d2 factor controls autolytic processes. Alkylhydroxybenzenes of both microbial and chemical origin were found to influence bacterial respiration. The low-molecular-weight osmoprotectant glycine betaine enhanced the thermostability of trypsin. This suggests that glycine betaine, like the d1 factor, serves as a molecular chaperone.

Profiling of the molecular weight and structural isomer abundance of macroalgae-derived phlorotannins.

PubMed

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

2015-01-16

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.

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

PubMed Central

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

Polyhedral oligomeric silsesquioxane grafted polymer in polymeric foam

DOEpatents

King, Bruce A.; Patankar, Kshitish A.; Costeux, Stephane; Jeon, Hyun K.

2017-01-17

A polymeric foam article with a polymer matrix defining multiple cells therein has a polymer component with a first polymer that is a polyhedral oligomeric silsesquioxane grafted polymer that has a weight-average molecular weight of two kilograms per mole or higher and 200 kilograms per mole or lower.

Purification of high-molecular-weight subfraction from porcine skin inhibiting proliferation of A431 human carcinoma epidermoid cells.

PubMed

Belova, O V; Sergienko, V I; Arion, V Ya; Lukanidina, T A; Moskvina, S N; Zimina, I V; Borisenko, G G; Lutsenko, G V; Grechikhina, M V; Kovaleva, E V; Klyuchnikova, Zh I

2014-07-01

Subfraction with a molecular weight >250 kDa isolated from porcine skin and inhibiting the proliferation of A431 human carcinoma epidermoid cells was purified by DEAE 32 anion exchange chromatography with NaCl concentration step-gradient. The effects of the initial subfraction and fractions obtained by separation in DEAE 32 on the proliferation of A431 human carcinoma epidermoid cells were studied in vitro in two tests (MTT and fluorescent test). The more sensitive fluorescent test showed the highest inhibitory activity of fraction No. 2 released from the column at 0.15 M NaCl. One major protein component and a series of minor protein components were detected in this fraction by vertical PAAG-SDS electrophoresis.

Quantitative characterization of solid epoxy resins using comprehensive two dimensional liquid chromatography coupled with electrospray ionization-time of flight mass spectrometry.

PubMed

Julka, Samir; Cortes, Hernan; Harfmann, Robert; Bell, Bruce; Schweizer-Theobaldt, Andreas; Pursch, Matthias; Mondello, Luigi; Maynard, Shawn; West, David

2009-06-01

A comprehensive multidimensional liquid chromatography system coupled to Electrospray Ionization-Mass Spectrometry (LCxLC-ESI-MS) was developed for detailed characterization and quantitation of solid epoxy resin components. The two orthogonal modes of separation selected were size exclusion chromatography (SEC) in the first dimension and liquid chromatography at critical conditions (LCCC) in the second dimension. Different components present in the solid epoxy resins were separated and quantitated for the first time based on the functional groups and molecular weight heterogeneity. Coupling LCxLC separations with mass spectrometry enabled the identification of components resolved in the two-dimensional space. Several different functional group families of compounds were separated and identified, including epoxy-epoxy and epoxy-alpha-glycol functional oligomers, and their individual molecular weight ranges were determined. Repeatability obtained ranged from 0.5% for the main product to 21% for oligomers at the 0.4% concentration level.

Analysis of amyloid fibrils in the cheetah (Acinonyx jubatus).

PubMed

Bergström, Joakim; Ueda, Mitsuharu; Une, Yumi; Sun, Xuguo; Misumi, Shogo; Shoji, Shozo; Ando, Yukio

2006-06-01

Recently, a high prevalence of amyloid A (AA) amyloidosis has been documented among captive cheetahs worldwide. Biochemical analysis of amyloid fibrils extracted from the liver of a Japanese captive cheetah unequivocally showed that protein AA was the main fibril constituent. Further characterization of the AA fibril components by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis revealed three main protein AA bands with approximate molecular weights of 8, 10 and 12 kDa. Mass spectrometry analysis of the 12-kDa component observed in SDS-PAGE and Western blotting confirmed the molecular weight of a 12,381-Da peak. Our finding of a 12-kDa protein AA component provides evidence that the cheetah SAA sequence is longer than the previously reported 90 amino acid residues (approximately 10 kDa), and hence SAA is part of the amyloid fibril.

Characterization of PMR-15 polyimide composition in thermo-oxidatively exposed graphite fiber composites

NASA Technical Reports Server (NTRS)

Alston, W. B.

1980-01-01

The contributions of individual resin components to total resin weight loss in 600 F air aged Celion 6000/PMR-15 polyimide composites were determined from the overall resin weight loss in the composite by chemically separating the PMR-15 matrix resin into its monomeric components. The individual resin components were also analyzed by spectroscopic techniques in order to elucidate curing and degradation mechanisms of the PMR-15 matrix resin. The isothermal weight loss of the individual resin components during prolonged 600 F thermo-oxidative aging of the composite was correlated to the changes observed in the Fourier Transform infrared spectra and Fourier Transform nuclear magnetic resonance spectra of the individual resin components. The correlation was used to identify the molecular site of the thermo-oxidative changes in PMR-15 polyimide matrix resin during 600 F curing the prolonged 600 F thermo-oxidative aging.

High performance lignin-acrylonitrile polymer blend materials

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

Naskar, Amit K.; Tran, Chau D.

A polymer blend material comprising: (i) a lignin component having a weight-average molecular weight of up to 1,000,000 g/mol; and (ii) an acrylonitrile-containing copolymer rubber component comprising acrylonitrile units in combination with diene monomer units, and having an acrylonitrile content of at least 20 mol %; wherein said lignin component is present in an amount of at least 5 wt % and up to about 95 wt % by total weight of components (i) and (ii); and said polymer blend material possesses a tensile yield stress of at least 5 MPa, or a tensile stress of at least 5 MPamore » at 10% elongation, or a tensile stress of at least 5 MPa at 100% elongation. Methods for producing the polymer blend, molded forms thereof, and articles thereof, are also described.« less

Enhanced characterization of oil sands acid-extractable organics fractions using electrospray ionization-high-resolution mass spectrometry and synchronous fluorescence spectroscopy.

PubMed

Bauer, Anthony E; Frank, Richard A; Headley, John V; Peru, Kerry M; Hewitt, L Mark; Dixon, D George

2015-05-01

The open pit oil sands mining operations north of Fort McMurray, Alberta, Canada, are accumulating tailings waste at a rate approximately equal to 4.9 million m(3) /d. Naphthenic acids are among the most toxic components within tailings to aquatic life, but structural components have largely remained unidentified. In the present study, electrospray ionization high-resolution mass spectrometry (ESI-HRMS) and synchronous fluorescence spectroscopy (SFS) were used to characterize fractions derived from the distillation of an acid-extractable organics (AEO) mixture isolated from oil sands process-affected water (OSPW). Mean molecular weights of each fraction, and their relative proportions to the whole AEO extract, were as follows: fraction 1: 237 Da, 8.3%; fraction 2: 240 Da, 23.8%; fraction 3: 257 Da, 26.7%; fraction 4: 308 Da, 18.9%; fraction 5: 355 Da, 10.0%. With increasing mean molecular weight of the AEO fractions, a concurrent increase occurred in the relative abundance of nitrogen-, sulfur-, and oxygen-containing ions, double-bond equivalents, and degree of aromaticity. Structures present in the higher-molecular-weight fractions (fraction 4 and fraction 5) suggested the presence of heteroatoms, dicarboxyl and dihydroxy groups, and organic acid compounds with the potential to function as estrogens. Because organic acid compositions become dominated by more recalcitrant, higher-molecular-weight acids during natural degradation, these findings are important in the context of oil sands tailings pond water remediation. © 2015 SETAC.

Real Time Monitoring of Dissolved Organic Carbon Concentration and Disinfection By-Product Formation Potential in a Surface Water Treatment Plant with Simulaneous UV-VIS Absorbance and Fluorescence Excitation-Emission Mapping

NASA Astrophysics Data System (ADS)

Gilmore, A. M.

2015-12-01

This study describes a method based on simultaneous absorbance and fluorescence excitation-emission mapping for rapidly and accurately monitoring dissolved organic carbon concentration and disinfection by-product formation potential for surface water sourced drinking water treatment. The method enables real-time monitoring of the Dissolved Organic Carbon (DOC), absorbance at 254 nm (UVA), the Specific UV Absorbance (SUVA) as well as the Simulated Distribution System Trihalomethane (THM) Formation Potential (SDS-THMFP) for the source and treated water among other component parameters. The method primarily involves Parallel Factor Analysis (PARAFAC) decomposition of the high and lower molecular weight humic and fulvic organic component concentrations. The DOC calibration method involves calculating a single slope factor (with the intercept fixed at 0 mg/l) by linear regression for the UVA divided by the ratio of the high and low molecular weight component concentrations. This method thus corrects for the changes in the molecular weight component composition as a function of the source water composition and coagulation treatment effects. The SDS-THMFP calibration involves a multiple linear regression of the DOC, organic component ratio, chlorine residual, pH and alkalinity. Both the DOC and SDS-THMFP correlations over a period of 18 months exhibited adjusted correlation coefficients with r2 > 0.969. The parameters can be reported as a function of compliance rules associated with required % removals of DOC (as a function of alkalinity) and predicted maximum contaminant levels (MCL) of THMs. The single instrument method, which is compatible with continuous flow monitoring or grab sampling, provides a rapid (2-3 minute) and precise indicator of drinking water disinfectant treatability without the need for separate UV photometric and DOC meter measurements or independent THM determinations.

Increase in gap junctional intercellular communication by high molecular weight hyaluronic acid associated with fibroblast growth factor 2 and keratinocyte growth factor production in normal human dermal fibroblasts.

PubMed

Park, Jeong Ung; Tsuchiya, Toshie

2002-07-01

The effects of different molecular weights of hyaluronic acid (HA), a major component of extracellular matrix, on gap junctional intercellular communication (GJIC) in normal human dermal fibroblasts (NHDF cells) were investigated. NHDF cells were cultured for 4 days with different molecular weights of HA and then the extent of GJIC was assessed by the scrape-loading dye transfer method, using Lucifer yellow. The area of dye transfer was greater in the dishes coated with HA than in those to which HA was added. Thus, NHDF cells cultured on surfaces coated with high molecular weight (HMW) HA (MW, 800 kDa) showed greatly enhanced GJIC. Furthermore, another aim of this study was to evaluate the effects of different molecular weights of HA on the production of FGF-2 and KGF, because both are important cytokines produced by NHDF cells. When FGF-2 and KGF cultured levels of cell extracts and media were determined by ELISA, both levels were significantly enhanced when cells were grown on plates coated with HMW HA. This finding indicated that the function of gap junction channels in NHDF cells grown on plates coated with HMW HA may promote the biosynthesis of growth factors such as FGF-2 and KGF.

Oral administration of hyaluronan prevents skin dryness and epidermal thickening in ultraviolet irradiated hairless mice.

PubMed

Kawada, Chinatsu; Kimura, Mamoru; Masuda, Yasunobu; Nomura, Yoshihiro

2015-12-01

Hyaluronan is a component of the extracellular matrix that plays a role in water retention in tissues. In this study, we orally administered hyaluronans of varying molecular weights (300k and less than 10k) repeatedly to hairless mice exposed to ultraviolet (UV) irradiation and examined their effects on the skin of these mice. UV irradiation induces a marked increase in the epidermal thickness of the dorsal skin and a marked decrease in the skin moisture content; however, orally administered hyaluronan, particularly that with a molecular weight of less than 10k, markedly reversed the increase and decrease in the epidermal thickness and skin moisture content, respectively. Furthermore, on analyzing the mice skin, orally administered hyaluronan with a molecular weight of less than 10k increased the levels of the HAS2 gene expression in the skin. Based on these findings, it is assumed that orally administered hyaluronans, with molecular weight of 300k and less than 10k, reversed UV irradiation-induced skin disturbance. In particular, it was considered that the increase in the skin moisture content by orally administered hyaluronan, with a molecular weight of less than 10k, was related to the effect on skin cells. Copyright © 2015 Elsevier B.V. All rights reserved.

The influence of malalignment and ageing following sterilisation by gamma irradiation in an inert atmosphere on the wear of ultra-high-molecular-weight polyethylene in patellofemoral replacements

PubMed Central

Maiti, Raman; Cowie, Raelene M; Fisher, John; Jennings, Louise M

2017-01-01

Complications of patellofemoral arthroplasty often occur soon after implantation and, as well as other factors, can be due to the design of the implant or its surgical positioning. A number of studies have previously considered the wear of ultra-high-molecular-weight polyethylene patellae following suboptimal implantation; however, studies have primarily been carried out under a limited number of degrees of freedom. The aim of this study was to develop a protocol to assess the wear of patellae under a malaligned condition in a six-axis patellofemoral joint simulator. The malalignment protocol hindered the tracking of the patella centrally in the trochlear groove and imparted a constant 5° external rotation (tilt) on the patella button. Following 3 million cycles of wear simulation, this condition had no influence on the wear of ultra-high-molecular-weight polyethylene patellae aged for 4 years compared to well-positioned non-aged implants (p > 0.05). However, under the malaligned condition, ultra-high-molecular-weight polyethylene patellae aged 8–10 years after unpacking (following sterilisation by gamma irradiation in an inert atmosphere) and worn ultra-high-molecular-weight polyethylene components also aged 4 years after unpacking (following the same sterilisation process) exhibited a high rate of wear. Fatigue failure due to elevated contact stress led to delamination of the ultra-high-molecular-weight polyethylene and in some cases complete failure of the patellae. The results suggest that suboptimal tracking of the patella in the trochlear groove and tilt of the patella button could have a significant effect on the wear of ultra-high-molecular-weight polyethylene and could lead to implant failure. PMID:28661229

The influence of malalignment and ageing following sterilisation by gamma irradiation in an inert atmosphere on the wear of ultra-high-molecular-weight polyethylene in patellofemoral replacements.

PubMed

Maiti, Raman; Cowie, Raelene M; Fisher, John; Jennings, Louise M

2017-07-01

Complications of patellofemoral arthroplasty often occur soon after implantation and, as well as other factors, can be due to the design of the implant or its surgical positioning. A number of studies have previously considered the wear of ultra-high-molecular-weight polyethylene patellae following suboptimal implantation; however, studies have primarily been carried out under a limited number of degrees of freedom. The aim of this study was to develop a protocol to assess the wear of patellae under a malaligned condition in a six-axis patellofemoral joint simulator. The malalignment protocol hindered the tracking of the patella centrally in the trochlear groove and imparted a constant 5° external rotation (tilt) on the patella button. Following 3 million cycles of wear simulation, this condition had no influence on the wear of ultra-high-molecular-weight polyethylene patellae aged for 4 years compared to well-positioned non-aged implants (p > 0.05). However, under the malaligned condition, ultra-high-molecular-weight polyethylene patellae aged 8-10 years after unpacking (following sterilisation by gamma irradiation in an inert atmosphere) and worn ultra-high-molecular-weight polyethylene components also aged 4 years after unpacking (following the same sterilisation process) exhibited a high rate of wear. Fatigue failure due to elevated contact stress led to delamination of the ultra-high-molecular-weight polyethylene and in some cases complete failure of the patellae. The results suggest that suboptimal tracking of the patella in the trochlear groove and tilt of the patella button could have a significant effect on the wear of ultra-high-molecular-weight polyethylene and could lead to implant failure.

Purification and characterization of allergens from Xanthium strumarium pollen.

PubMed

Jaggi, K S; Gangal, S V

1987-12-01

The allergenic components present in whole pollen extract of Xanthium strumarium were isolated by sequential ammonium sulphate precipitation, DEAE Sephadex A50 chromatography and gel filtration. The techniques of RAST inhibition and skin test were utilized to check the allergenicity of fractionated proteins revealing the presence of Xan Ib and Xan VIa as the important allergenic components. Xan Ib was found to be devoid of carbohydrate and had a molecular weight of 103,000 daltons. Xan VIa was a glycoprotein of molecular weight 17,000 daltons. The carbohydrate moiety of Xan VIa was found to be associated with allergenicity. The characteristic pattern of whole pollen extract on CIE and TLIEF showed 36 and 21 protein bands, respectively. The use of FPLC in isolation of partially purified allergens from Xanthium is discussed.

Hansen solubility parameters for polyethylene glycols by inverse gas chromatography.

PubMed

Adamska, Katarzyna; Voelkel, Adam

2006-11-03

Inverse gas chromatography (IGC) has been applied to determine solubility parameter and its components for nonionic surfactants--polyethylene glycols (PEG) of different molecular weight. Flory-Huggins interaction parameter (chi) and solubility parameter (delta(2)) were calculated according to DiPaola-Baranyi and Guillet method from experimentally collected retention data for the series of carefully selected test solutes. The Hansen's three-dimensional solubility parameters concept was applied to determine components (delta(d), delta(p), delta(h)) of corrected solubility parameter (delta(T)). The molecular weight and temperature of measurement influence the solubility parameter data, estimated from the slope, intercept and total solubility parameter. The solubility parameters calculated from the intercept are lower than those calculated from the slope. Temperature and structural dependences of the entopic factor (chi(S)) are presented and discussed.

A stimulatory effect of Artemisia leaf extract on the proliferation of cultured endothelial cells.

PubMed

Kaji, T; Kaga, K; Miezi, N; Ejiri, N; Sakuragawa, N

1990-02-01

To investigate the effect of the hot water extract from Artemisia leaf (Artemisia princeps Panpanini) (AFE) on the proliferation of endothelial cells, the cells from bovine aorta were cultured for up to 96 h in the presence of 1, 5, 10 or 50 micrograms/ml AFE in RPMI1640 medium supplemented with 10% fetal bovine serum. After a 72 h culture, the cell number was significantly increased by AFE at 1, 5 and 10 micrograms/ml. An increase in the cell number by 5 micrograms/ml AFE observed after a 72 or 96 h treatment. The incorporations of both [3H]thymidine and [14C]leucine by the growing cells were significantly increased by 5 micrograms/ml AFE after a 72 h treatment. In addition, the incorporation of [3H]thymidine by either growing or confluent cells was significantly increased by 50 micrograms/ml AFE after a 72 h treatment. The stimulatory activity of AFE was recognized in the low-molecular-weight fraction (molecular weight less than or equal to 10000 dalton). These results clearly indicated that AFE contained some low-molecular-weight component(s) which stimulates the proliferation of vascular endothelial cells in vitro.

Characterization of dissolved organic matter in Dongjianghu Lake by UV-visible absorption spectroscopy with multivariate analysis.

PubMed

Zhu, Yanzhong; Song, Yonghui; Yu, Huibin; Liu, Ruixia; Liu, Lusan; Lv, Chunjian

2017-08-08

UV-visible absorption spectroscopy coupled with principal component analysis (PCA) and hierarchical cluster analysis (HCA) was applied to characterize spectroscopic components, detect latent factors, and investigate spatial variations of dissolved organic matter (DOM) in a large-scale lake. Twelve surface water samples were collected from Dongjianghu Lake in China. DOM contained lignin and quinine moieties, carboxylic acid, microbial products, and aromatic and alkyl groups, which in the northern part of the lake was largely different from the southern part. Fifteen spectroscopic indices were deduced from the absorption spectra to indicate molecular weight or humification degree of DOM. The northern part of the lake presented the smaller molecular weight or the lower humification degree of DOM than the southern part. E 2/4 , E 3/4 , E 2/3 , and S 2 were latent factors of characterizing the molecular weight of DOM, while E 2/5 , E 3/5 , E 2/6 , E 4/5 , E 3/6 , and A 2/1 were latent factors of evaluating the humification degree of DOM. The UV-visible absorption spectroscopy combined with PCA and HCA may not only characterize DOM fractions of lakes, but may be transferred to other types of waterscape.

Variables controlling the recovery of ignitable liquid residues from simulated fire debris samples using solid-phase microextraction/gas chromatography

NASA Astrophysics Data System (ADS)

Furton, Kenneth G.; Almirall, Jose R.; Wang, Jing

1999-02-01

In this paper, we present data comparing a variety of different conditions for extracting ignitable liquid residues from simulated fire debris samples in order to optimize the conditions for using Solid Phase Microextraction. A simulated accelerant mixture containing 30 components, including those from light petroleum distillates, medium petroleum distillates and heavy petroleum distillates were used to study the important variables controlling Solid Phase Microextraction (SPME) recoveries. SPME is an inexpensive, rapid and sensitive method for the analysis of volatile residues from the headspace over solid debris samples in a container or directly from aqueous samples followed by GC. The relative effects of controllable variables, including fiber chemistry, adsorption and desorption temperature, extraction time, and desorption time, have been optimized. The addition of water and ethanol to simulated debris samples in a can was shown to increase the sensitivity when using headspace SPME extraction. The relative enhancement of sensitivity has been compared as a function of the hydrocarbon chain length, sample temperature, time, and added ethanol concentrations. The technique has also been optimized to the extraction of accelerants directly from water added to the fire debris samples. The optimum adsorption time for the low molecular weight components was found to be approximately 25 minutes. The high molecular weight components were found at a higher concentration the longer the fiber was exposed to the headspace (up to 1 hr). The higher molecular weight components were also found in higher concentrations in the headspace when water and/or ethanol was added to the debris.

Molecular composition and volatility of isoprene photochemical oxidation secondary organic aerosol under low- and high-NOx conditions

NASA Astrophysics Data System (ADS)

D'Ambro, Emma L.; Lee, Ben H.; Liu, Jiumeng; Shilling, John E.; Gaston, Cassandra J.; Lopez-Hilfiker, Felipe D.; Schobesberger, Siegfried; Zaveri, Rahul A.; Mohr, Claudia; Lutz, Anna; Zhang, Zhenfa; Gold, Avram; Surratt, Jason D.; Rivera-Rios, Jean C.; Keutsch, Frank N.; Thornton, Joel A.

2017-01-01

We present measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation in an environmental simulation chamber at a variety of oxidant conditions and using dry neutral seed particles to suppress acid-catalyzed multiphase chemistry. A high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) utilizing iodide-adduct ionization coupled to the Filter Inlet for Gases and Aerosols (FIGAERO) allowed for simultaneous online sampling of the gas and particle composition. Under high-HO2 and low-NO conditions, highly oxygenated (O : C ≥ 1) C5 compounds were major components (˜ 50 %) of SOA. The SOA composition and effective volatility evolved both as a function of time and as a function of input NO concentrations. Organic nitrates increased in both the gas and particle phases as input NO increased, but the dominant non-nitrate particle-phase components monotonically decreased. We use comparisons of measured and predicted gas-particle partitioning of individual components to assess the validity of literature-based group-contribution methods for estimating saturation vapor concentrations. While there is evidence for equilibrium partitioning being achieved on the chamber residence timescale (5.2 h) for some individual components, significant errors in group-contribution methods are revealed. In addition, > 30 % of the SOA mass, detected as low-molecular-weight semivolatile compounds, cannot be reconciled with equilibrium partitioning. These compounds desorb from the FIGAERO at unexpectedly high temperatures given their molecular composition, which is indicative of thermal decomposition of effectively lower-volatility components such as larger molecular weight oligomers.

Rheological Properties of Gels from Pyrene Based Low Molecular Weight Gelators

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

Leivo, Kimmo T.; Hahma, Arno P.

2008-07-07

Gels of pyrene derived low molecular weight organogelators (LMOGs) in primary alcohols have been characterized by rheometry and scanning electron microscopy. Total gelator concentration was 1-2.7 % w/w depending on the solvent and the gelator, including equimolar amounts of the gelator and 2,4,7-trinitrofluorenone (TNF), which is necessary for gelation. Thermoreversible and strongly shear thinning gels were achieved as the two components interact non-covalently to form a gel network. A qualitative correlation between the rheological properties and the nanoscale gel structure were found.

Rheological Properties of Gels from Pyrene Based Low Molecular Weight Gelators

NASA Astrophysics Data System (ADS)

Leivo, Kimmo T.; Hahma, Arno P.

2008-07-01

Gels of pyrene derived low molecular weight organogelators (LMOGs) in primary alcohols have been characterized by rheometry and scanning electron microscopy. Total gelator concentration was 1-2.7 % w/w depending on the solvent and the gelator, including equimolar amounts of the gelator and 2,4,7-trinitrofluorenone (TNF), which is necessary for gelation. Thermoreversible and strongly shear thinning gels were achieved as the two components interact non-covalently to form a gel network. A qualitative correlation between the rheological properties and the nanoscale gel structure were found.

Characterization of low molecular weight dissolved natural organic matter along the treatment trait of a waterworks using Fourier transform ion cyclotron resonance mass spectrometry.

PubMed

Zhang, Haifeng; Zhang, Yahe; Shi, Quan; Ren, Shuoyi; Yu, Jianwei; Ji, Feng; Luo, Wenbin; Yang, Min

2012-10-15

Dissolved natural organic matter (DOM), particularly the low molecular weight DOM, can affect the performance of water treatment processes and serve as a main precursor of disinfection by-products (DBPs) during chlorination. In this study, electrospray ionization coupled to Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) was used to characterize the low molecular weight DOM along the treatment trait of a conventional drinking water treatment plant. The ESI FT-ICR MS data showed that various C, H, O-only class species were the major components in the source water. According to the van Krevelen diagram analysis, lignin- and tannin-like compounds were the most abundant components. Within an isobaric group, the DOM molecules with a high degree of oxidation (high O/C value) were preferentially removed during coagulation, while those with low degree of oxidation were found to be more reactive toward chlorine. In addition, 357 one-chlorine containing products and 199 two-chlorine containing products formed during chlorination were detected in the chlorination effluent sample at a high confidence level. The chlorinated products can be arranged into series, suggesting that they were originated from C, H, O-only precursor compounds, which were in series related by the replacement of CH(4) against oxygen. For the first time, this study explored the behavior of low molecular weight DOM along a drinking water treatment trait on the molecular level, and revealed the presence of abundant unknown chlorinated products, which are probably rich in carboxylic and phenolic groups, in drinking water. Copyright © 2012 Elsevier Ltd. All rights reserved.

Surface accumulation of low molecular weight dissolved organic matter in surface waters and horizontal off-shelf spreading of nutrients and humic-like fluorescence in the Chukchi Sea of the Arctic Ocean.

PubMed

Chen, Meilian; Jung, Jinyoung; Lee, Yun Kyung; Hur, Jin

2018-05-23

Polar regions play unique roles in global overturning circulation, carbon cycling, and climate change. In this study, seawater dissolved organic matter (DOM) was characterized for the Chukchi Sea in the Arctic Ocean in the summer season. The seawater generally contains high concentrations of dissolved organic carbon (DOC, up to 92 μM C) and tyrosine-like fluorescence (up to 0.21 RU), and it was enriched with heteroatomic molecular formula with nitrogen-containing and sulfur-containing formulas counting 2246 (~41% of total identified molecular formula) and 1838 (~34%), respectively. Significant correlations were observed between salinity and the absorption coefficient at 254 nm, between chlorophyll-a and DOC as well as the tyrosine-like component, C 270/302 (C ex/em maxima), and between biological index and two protein-like components, C 275/338 and C 305/344 . A comparison between surface waters and close-to-seafloor deep waters suggested a trend of the accumulation of low molecular weight (LMW) fraction (~54-74%, nominal average molecular weight M n  < ~350 Da) in the surface waters. Another interesting finding from spatial data was an obvious horizontal off-shelf spreading of nutrients and humic-like fluorescence. This study sheds novel insights of DOM characteristics and dynamics in the highly productive polar sea. Copyright © 2018 Elsevier B.V. All rights reserved.

Complex Forms of Soil Organic Phosphorus-A Major Component of Soil Phosphorus.

PubMed

McLaren, Timothy I; Smernik, Ronald J; McLaughlin, Mike J; McBeath, Therese M; Kirby, Jason K; Simpson, Richard J; Guppy, Christopher N; Doolette, Ashlea L; Richardson, Alan E

2015-11-17

Phosphorus (P) is an essential element for life, an innate constituent of soil organic matter, and a major anthropogenic input to terrestrial ecosystems. The supply of P to living organisms is strongly dependent on the dynamics of soil organic P. However, fluxes of P through soil organic matter remain unclear because only a minority (typically <30%) of soil organic P has been identified as recognizable biomolecules of low molecular weight (e.g., inositol hexakisphosphates). Here, we use (31)P nuclear magnetic resonance spectroscopy to determine the speciation of organic P in soil extracts fractionated into two molecular weight ranges. Speciation of organic P in the high molecular weight fraction (>10 kDa) was markedly different to that of the low molecular weight fraction (<10 kDa). The former was dominated by a broad peak, which is consistent with P bound by phosphomonoester linkages of supra-/macro-molecular structures, whereas the latter contained all of the sharp peaks that were present in unfractionated extracts, along with some broad signal. Overall, phosphomonoesters in supra-/macro-molecular structures were found to account for the majority (61% to 73%) of soil organic P across the five diverse soils. These soil phosphomonoesters will need to be integrated within current models of the inorganic-organic P cycle of soil-plant terrestrial ecosystems.

Molecular Structural Characteristics of Polysaccharide Fractions from Canarium album (Lour.) Raeusch and Their Antioxidant Activities.

PubMed

Zeng, Hongliang; Miao, Song; Zheng, Baodong; Lin, Shan; Jian, Yeye; Chen, Shen; Zhang, Yi

2015-11-01

The objective of this study was to investigate the multiple relations between the preliminary molecular structural characteristics and antioxidant activities of polysaccharides from Canarium album (Lour.) Raeusch (CPS). Three polysaccharide fractions, CPS1, CPS2, and CPS3, were isolated from CPS by column chromatography. CPS1 and CPS3 were mainly composed of neutral polysaccharides linked by α- and β-glycosidic linkages while CPS2 was pectin polysaccharides mainly linked by β-glycosidic linkages. According to the SEC-MALLS-RI system, the molecular weight of CPS1 was greater compared to CPS2 and CPS3, and the molecular weight and radius of CPS did not display positive correlation. The chain conformation analysis indicated CPS1 and CPS2 were typical highly branched polysaccharides while CPS3 existed as a globular shape in aqueous. Furthermore, the antioxidant activity of CPS2 was better than that of CPS3, while that of CPS1 was the weakest. The antioxidant activities of polysaccharide fractions were affected by their monosaccharide composition, glycosidic linkage, molecular weight, and chain conformation. This functional property was a result of a combination of multiple molecular structural factors. CPS2 was the major antioxidant component of CPS and it could be exploited as a valued antioxidant product. The molecular structural characteristics, antioxidant activities, and structure-function relationships of polysaccharide fractions from Canarium album were first investigated in this study. The results provided background and practical knowledge for the deep-processed products of C. album with high added value. CPS2 was the major antioxidant component of CPS, which could be exploited as a valued antioxidant ingredient in food and pharmaceutical industries. © 2015 Institute of Food Technologists®

Characterization of molecular structural changes in pectin during juice cloud destabilization in frozen concentrated orange juice

USDA-ARS?s Scientific Manuscript database

Pectin comprises one of the major components of cloud material in citrus juices. Juice cloud is a complex mixture of polysaccharides, proteins and lower molecular weight compounds that are responsible for the turbid appearance of citrus juices. The stability of juice cloud depends on a number of fac...

Molecular chaperone properties of the high molecular weight aggregate from aged lens

NASA Technical Reports Server (NTRS)

Takemoto, L.; Boyle, D.; Spooner, B. S. (Principal Investigator)

1994-01-01

The high molecular weight aggregate (HMWA) fraction was isolated from the water soluble proteins of aged bovine lenses. Its composition and ability to inhibit heat-induced denaturation and aggregation were compared with the lower molecular weight, oligomeric fraction of alpha isolated from the same lens. Although the major components of both fractions were the alpha-A and alpha-B chains, the HMWA fraction possessed a decreased ability to protect other proteins against heat-induced denaturation and aggregation. Immunoelectron microscopy of both fractions demonstrated that alpha particles from the HMWA fraction contained increased amounts of beta and gamma crystallins, bound to a central region of the supramolecular complex. Together, these results demonstrate that alpha crystallins found in the HMWA fraction possess a decreased ability to protect against heat-induced denaturation and aggregation, and suggest that at least part of this decrease could be due to the increased presence of beta and gamma crystallins complexed to the putative chaperone receptor site of the alpha particles.

40 CFR 60.564 - Test methods and procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

.... If the carrier component of the gas stream is nitrogen, then an average molecular weight of 28 g/g... from materials balance by good engineering practice. (i) The owner or operator shall determine...

40 CFR 60.564 - Test methods and procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

.... If the carrier component of the gas stream is nitrogen, then an average molecular weight of 28 g/g... from materials balance by good engineering practice. (i) The owner or operator shall determine...

40 CFR 60.564 - Test methods and procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... If the carrier component of the gas stream is nitrogen, then an average molecular weight of 28 g/g... from materials balance by good engineering practice. (i) The owner or operator shall determine...

40 CFR 60.564 - Test methods and procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

.... If the carrier component of the gas stream is nitrogen, then an average molecular weight of 28 g/g... from materials balance by good engineering practice. (i) The owner or operator shall determine...

Chitosan derivatives with antimicrobial, antitumour and antioxidant activities--a review.

PubMed

Jarmila, Vinsová; Vavríková, Eva

2011-01-01

Chitosan is a linear polysaccharide with a good biodegradability, biocompatibility, and no toxicity, which provide it with huge potential for future development. The chitosan molecule appears to be a suitable polymeric complex for many biomedical applications. This review gathers current findings on the antibacterial, antifungal, antitumour and antioxidant activities of chitosan derivatives and concurs with our previous review presenting data collected up to 2008. Antibacterial activity is based on molecular weight, the degree of deacetylation, the type of substitutents, which can be cationic or easily form cations, and the type of bacterium. In general, high molecular weight chitosan cannot pass through cell membranes and forms a film that protects cells against nutrient transport through the microbial cell membrane. Low molecular weight chitosan derivatives are water soluble and can better incorporate the active molecule into the cell. Gram-negative bacteria, often represented by Escherichia coli, have an anionic bacterial surface on which cationic chitosan derivatives interact electrostatically. Thus, many chitosan conjugates have cationic components such as ammonium, pyridinium or piperazinium substituents introduced into their molecules to increase their positive charge. Gram-positive bacteria like Staphylococcus aureus are inhibited by the binding of lower molecular weight chitosan derivatives to DNA or RNA. Chitosan nanoparticles exhibit an increase in loading capacity and efficacy. Antitumour active compounds such as doxorubicin, paclitaxel, docetaxel and norcantharidin are used as drug carriers. It is evident that chitosan, with its low molecular weight, is a useful carrier for molecular drugs requiring targeted delivery. The antioxidant scavenging activity of chitosan has been established by the strong hydrogen-donating ability of chitosan. The low molecular weight and greater degree of quarternization have a positive influence on the antioxidant activity of chitosan. Phenolic and polyphenolic compounds with antioxidant effects are condensed with chitosan to form mutual prodrugs.

Changes in Light Absorptivity of Molecular Weight Separated Brown Carbon Due to Photolytic Aging.

PubMed

Wong, Jenny P S; Nenes, Athanasios; Weber, Rodney J

2017-08-01

Brown carbon (BrC) consists of those organic compounds in atmospheric aerosols that absorb solar radiation and may play an important role in planetary radiative forcing and climate. However, little is known about the production and loss mechanisms of BrC in the atmosphere. Here, we study how the light absorptivity of BrC from wood smoke and secondary BrC generated from the reaction of ammonium sulfate with methylglyoxal changes under photolytic aging by UVA radiation in the aqueous phase. Owing to its chemical complexity, BrC is separated by molecular weight using size exclusion chromatography, and the response of each molecular weight fraction to aging is studied. Photolytic aging induced significant changes in the light absorptivity of BrC for all molecular weight fractions; secondary BrC was rapidly photoblenched, whereas for wood smoke BrC, both photoenhancement and photobleaching were observed. Initially, large biomass burning BrC molecules were rapidly photoenhanced, followed by slow photolysis. As a result, large BrC molecules dominated the total light absorption of aged biomass burning BrC. These experimental results further support earlier observations that large molecular weight BrC compounds from biomass burning can be relatively long-lived components in atmospheric aerosols, thus more likely to have larger impacts on aerosol radiative forcing and could serve as biomass burning tracers.

Near-monodisperse sodium polymethacrylates: characterization by linear salt gradient anion-exchange chromatography

PubMed

Freydank; Krasia; Tiddy; Patrickios

2000-05-01

A family of six near-monodisperse homopolymers of sodium methacrylate (Mn = 1100, 3200, 5500, 7200, 14100, and 21000) is characterized by linear salt gradient anion-exchange chromatography. Although the retention times depend on the initial and final salt concentrations of the gradient, they are almost independent of the molecular weight of poly(sodium methacrylate). This suggests that anion-exchange chromatography is incapable of resolving mixtures of a given polyelectrolyte to their components of various molecular weights, and it is therefore impossible to identify the polydispersity of such a sample using this method. The independence of the retention times from molecular weight is also predicted by a theory based on stoichiometric mass-action ion-exchange. Using this theory and our experimental retention times, the equilibrium anion-exchange constant and the corresponding Gibbs free energy of anion-exchange of the monomer repeat unit are calculated to be around 2.1 and -1.8 kJ/mol, respectively.

HA metabolism in skin homeostasis and inflammatory disease.

PubMed

Kavasi, Rafaela-Maria; Berdiaki, Aikaterini; Spyridaki, Ioanna; Corsini, Emanuela; Tsatsakis, Aristidis; Tzanakakis, George; Nikitovic, Dragana

2017-03-01

Hyaluronan (HA), an unsulfated glycosaminoglycan, is an important component of the complex extracellular matrix network which surrounds and supports cells in tissues. HA is detected in all vertebrate tissues, but the bulk of HA is produced and deposited in the skin. In this review we focus on the role of HA in skin-associated inflammatory disease and wound healing. Properties of HA are directly dependent on its molecular weight. Thus, high molecular weight HA (HMWHA) is deposited in normal tissues during homeostasis and promotes their stability whereas low molecular weight HA fragments (LMWHA), on the other hand, may arise from enzymatic or chemical activities. The degradation of HMWHA to LMWHA fragments, often leads to the generation of biologically active oligosaccharides with different properties and postulated functions in wound scar formation and inflammation. More detailed studies of HA involvement in skin-associated inflammatory disease may result in novel treatment modalities. Copyright © 2017 Elsevier Ltd. All rights reserved.

Surface properties of poly(acrylonitrile) (PAN) precipitation polymerized in supercritical CO2 and the influence of the molecular weight.

PubMed

Shen, Qing; Gu, Qing-Feng; Hu, Jian-Feng; Teng, Xin-Rong; Zhu, Yun-Feng

2003-11-15

In this paper, the surface properties, e.g., the total surface free energy and the related Lifshitz-van der Waals and Lewis acid-base components, of polyacrylonitrile (PAN) precipitation polymerized in supercritical CO(2) have been characterized. Moreover, the influence of molecular weight varying has been also investigated. Results show that the surface properties of PAN resulting from supercritical CO(2) are different from those obtained by the conventional method. Of these data, one important finding is that the supercritical CO(2) PAN seems to decrease the surface free energy with the increased molecular weight. Based on previous recorded NMR spectra of this PAN and especially compared to commercial PAN, such phenomena are discussed and ascribed to an increase of the H-bonds and a reduction of the isotacticity in the supercritical CO(2) condition for PAN.

PETROLEUM RESIDUA SOLUBILITY PARAMETER/POLARITY MAP: STABILITY STUDIES OF RESIDUA PYROLYSIS

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

John F. Schabron; A. Troy Pauli; Joseph F. Rovani, Jr.

1999-04-30

A new molecular weight/polarity map based on the Scatchard-Hildebrand solubility equation has been developed for petroleum residua. A series of extractions are performed with solvents of increasing solubility parameter, and the fractions are analyzed by vapor pressure osmometry for number average molecular weight and by analytical-scale size exclusion chromatography for molecular weight spread. Work was performed for a heavy oil material subjected to three increasing severities of thermal treatment prior to and through the onset of coke formation. The results are diagnostic of the layers of solvations by resin-type molecules around a central asphaltene core. Two additional stability diagnostic methodsmore » were also used. These were the Heithaus titration ''P-index'' and Gaestel ''G'' index, which have been applied to paving asphalts for decades. The Heithaus titration involves the titration of three toluene solutions of a residuum at three concentrations with a poor solvent, such as isooctane, to the point of asphaltene flocculation. In the present work, the significance of the data are developed in terms of the Hildebrand solubility parameter. The Heithaus results are combined with data from the new molecular weight/polarity map. The solubility parameters for the toluene-soluble asphaltene components are measured, and the solubility parameters of the maltenes can be calculated. As thermal treatment progresses, the solubility parameters of asphaltene materials increase and the molecular weights decrease. A new coking index is proposed based on Heithaus titration data. Preliminary results suggest that an alternative, simpler coking index may be developed by measuring the weight percent of cyclohexane solubles in heptane asphaltenes. Coking onset appears to coincide with the depletion of these resin-type asphaltene solubilizing components of residua. The objective of the present study was to develop a mapping tool that will enhance understanding of the changes that occur in residua during upgrading and support the industry-sponsored work in which Western Research Institute is engaged. WRI performs proprietary industry-sponsored residua and heavy oil upgrading process development and optimization research. The new mapping tool can be used for evaluating heavy oils and residua in both upstream and downstream operations.« less

Molecular composition and volatility of isoprene photochemical oxidation secondary organic aerosol under low- and high-NO x conditions

DOE PAGES

D'Ambro, Emma L.; Lee, Ben H.; Liu, Jiumeng; ...

2017-01-04

Here, we present measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation in an environmental simulation chamber at a variety of oxidant conditions and using dry neutral seed particles to suppress acid-catalyzed multiphase chemistry. A high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) utilizing iodide-adduct ionization coupled to the Filter Inlet for Gases and Aerosols (FIGAERO) allowed for simultaneous online sampling of the gas and particle composition. Under high-HO 2 and low-NO conditions, highly oxygenated (O : C ≥ 1) C 5 compounds were major components (~50%) of SOA. The SOA composition and effective volatility evolved both as amore » function of time and as a function of input NO concentrations. Organic nitrates increased in both the gas and particle phases as input NO increased, but the dominant non-nitrate particle-phase components monotonically decreased. We use comparisons of measured and predicted gas-particle partitioning of individual components to assess the validity of literature-based group-contribution methods for estimating saturation vapor concentrations. While there is evidence for equilibrium partitioning being achieved on the chamber residence timescale (5.2 h) for some individual components, significant errors in group-contribution methods are revealed. In addition, >30% of the SOA mass, detected as low-molecular-weight semivolatile compounds, cannot be reconciled with equilibrium partitioning. These compounds desorb from the FIGAERO at unexpectedly high temperatures given their molecular composition, which is indicative of thermal decomposition of effectively lower-volatility components such as larger molecular weight oligomers.« less

[Component and content changes of volatiles from Chinese cabbage damaged by Plutella xylostella].

PubMed

Yang, Guang; You, Minsheng; Wei, Hui

2004-11-01

The study showed that Chinese cabbage, Brassica campestris could release a variety of volatiles, especially when infested by Plutella xylostella larvae. Among these volatiles, saturated hydrocarbon was dominant, aromatic hydrocarbon was the second, and unsaturated hydrocarbon, aldehyde, alcohol, ketone, acid and heteroaromatic compounds were existed with a small amount. Chinese cabbage damaged by Plutella xylostella larvae produced 3 times of volatiles in amount with more species than the control. The volatiles from control plants were mostly of small molecular weight, and those from Chinese cabbage damaged by Plutella xylostella were mostly of high molecular weight.

High-pressure size exclusion chromatography analysis of dissolved organic matter isolated by tangential-flow ultra filtration

USGS Publications Warehouse

Everett, C.R.; Chin, Y.-P.; Aiken, G.R.

1999-01-01

A 1,000-Dalton tangential-flow ultrafiltration (TFUF) membrane was used to isolate dissolved organic matter (DOM) from several freshwater environments. The TFUF unit used in this study was able to completely retain a polystyrene sulfonate 1,800-Dalton standard. Unaltered and TFUF-fractionated DOM molecular weights were assayed by high-pressure size exclusion chromatography (HPSEC). The weight-averaged molecular weights of the retentates were larger than those of the raw water samples, whereas the filtrates were all significantly smaller and approximately the same size or smaller than the manufacturer-specified pore size of the membrane. Moreover, at 280 nm the molar absorptivity of the DOM retained by the ultrafilter is significantly larger than the material in the filtrate. This observation suggests that most of the chromophoric components are associated with the higher molecular weight fraction of the DOM pool. Multivalent metals in the aqueous matrix also affected the molecular weights of the DOM molecules. Typically, proton-exchanged DOM retentates were smaller than untreated samples. This TFUF system appears to be an effective means of isolating aquatic DOM by size, but the ultimate size of the retentates may be affected by the presence of metals and by configurational properties unique to the DOM phase.

Antioxidant and antibacterial activities of polysaccharides isolated and purified from Diaphragma juglandis fructus.

PubMed

Meng, Qingran; Li, Yinghao; Xiao, Tiancun; Zhang, Lianfu; Xu, Dan

2017-12-01

A water-soluble polysaccharide fraction (DJP-2) isolated from Diaphragma juglandis was successfully purified by ion-exchange chromatography (DEAE-cellulose) and gel-permeation chromatography (Sephadex G-100). The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of DJP-2 were 4.95 and 3.99kDa, respectively. Monosaccharide component analysis indicated that DJP-2 comprised arabinose, galactose, glucose, xylose, and mannose in a molar ratio of 0.27:0.55:1:0.14:0.08. The evaluation of the antioxidant and antibacterial activities of polysaccharides from Diaphragma juglandis fructus indicated that they could be explored as promising natural antioxidant and bacteriostatic agents in the food and pharmaceutical industries. Copyright © 2017 Elsevier B.V. All rights reserved.

Honey melanoidins: Analysis of the compositions of the high molecular weight melanoidins exhibiting radical-scavenging activity.

PubMed

Brudzynski, Katrina; Miotto, Danielle

2011-08-01

Size-exclusion chromatography (SEC) and activity-guided fractionation of honeys allowed the isolation of high molecular weight brown compounds, ranging in size from 66 to 235kDa that exhibited peroxyl radical-scavenging activity. Their concentrations, antioxidant activity and degree of browning increased after heat-treatment of honeys, suggesting that they represent melanoidins. Chemical analysis of melanoidins demonstrated the presence of proteins, polyphenols and oligosaccharides. Heat-treatment caused an increased incorporation of phenolics into high molecular weight melanoidins and drastically decreased the protein content in these fractions with a concomitant appearance of high molecular weight protein-polyphenol complexes of reduced solubility. LC-ESI-MS demonstrated the presence of oligosaccharide moieties, supporting the postulated origin of melanoidins. The changes in the phenolic content of melanoidins from heated honeys were strongly correlated with their oxygen radical absorbance capacity (ORAC) values (R=0.75, p<0.0001), indicating that polyphenols contribute to the antioxidant activity of melanoidins. In summary, honey melanoidins are multi-component polymers consisting of protein-polyphenol-oligosaccharide complexes. A direct interaction between polyphenols and melanoidins resulted in a loss or gain of function for melanoidin antioxidant activity. Copyright © 2011 Elsevier Ltd. All rights reserved.

Sieving polymer synthesis by reversible addition fragmentation chain transfer polymerization.

PubMed

Nai, Yi Heng; Jones, Roderick C; Breadmore, Michael C

2013-12-01

Replaceable sieving polymers are the fundamental component for high resolution nucleic acids separation in CE. The choice of polymer and its physical properties play significant roles in influencing separation performance. Recently, reversible addition fragmentation chain transfer (RAFT) polymerization has been shown to be a versatile polymerization technique capable of yielding well defined polymers previously unattainable by conventional free radical polymerization. In this study, a high molecular weight PDMA at 765 000 gmol-1 with a PDI of 1.55 was successfully synthesized with the use of chain transfer agent - 2-propionic acidyl butyl trithiocarbonate (PABTC) in a multi-step sequential RAFT polymerization approach. This study represents the first demonstration of RAFT polymerization for synthesizing polymers with the molecular weight range suitable for high resolution DNA separation in sieving electrophoresis. Adjustment of pH in the reaction was found to be crucial for the successful RAFT polymerization of high molecular weight polymer as the buffered condition minimizes the effect of hydrolysis and aminolysis commonly associated with trithiocarbonate chain transfer agents. The separation efficiency of PABTC-PDMA was found to have marginally superior separation performance compared to a commercial PDMA formulation, POP™-CAP, of similar molecular weight range.

Developmental co-expression of small molecular weight apolipoprotein B synthesis and triacylglycerol secretion

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

Coleman, R.A.; Haynes, E.B.; Sand, T.M.

1987-05-01

The development of the liver's ability to coordinately express the synthesis and secretion of the two major components of very low density lipoproteins (VLDL): triacylglycerol (TG) and apolipoprotein B (apo B) was examined in cultured hepatocytes obtained from fetal, suckling and adult rats. Hepatocytes from fetal and suckling rats synthesized and secreted TG at rates lower than that displayed by adult cells. When TG synthesis was equalized by adding oleic acid to the culture medium, fetal cells still secreted only 39% as much TG as did adult cells. To determine the basis for the apparent defect in VLDL assembly/secretion displayedmore » by fetal cells, the synthesis and secretion of (TVS)methionine-labeled apo B was quantified by immunoprecipitation. Although adult and fetal cells synthesized and secreted large molecular weight apo B at similar rates, the synthesis and secretion of small molecular weight apo B was 2-fold greater in adult cells. These data suggest that the ability to assemble/secrete VLDL triacylglycerol varies in parallel with the developmental expression of small molecular weight apo B. Furthermore, these studies show the usefulness of the cultured rat hepatocyte model for examining the ontogeny and regulation of VLDL assembly/secretion.« less

Development of mass production technology for block copolymer lithographic materials

NASA Astrophysics Data System (ADS)

Himi, Toshiyuki; Matsuki, Ryota; Kosaka, Terumasa; Ogaki, Ryosuke; Kawaguchi, Yukio; Shimizu, Tetsuo

2017-03-01

We have successfully synthesized various and over wide range molecular weight block copolymers (BCPs): these are polystyrene(PS)-polymethylmethacrylate(PMMA) as general components and poly(4-trimethylsilylstyrene)(PTMSS)- poly(4-hydroxystyrene)(PHS) system as very strong segregated components (high chi) and multiblock type of those copolymers which form the microphase-separated structure pattern using living anionic polymerizing method by which the size of polymer can be precisely controlled. In addition, we were able to observe alternating lamellar and cylinder structures which were formed by our various BCPs using small angle X-ray scattering (SAXS). Moreover, we have successfully developed new apparatus for high volume manufacturing including our original technologies such as purification of monomer, improvement of wetted surface, and mechanical technology for high vacuum. And we have successfully synthesized all the BCPs with narrow molecular weight distribution (PDI <1.1) with large-scale apparatus.

Antioxidant activities of crude phlorotannins from Sargassum hemiphyllum.

PubMed

Zhao, Zhi-Li; Yang, Xiao-Qing; Gong, Zhong-Qing; Pan, Ming-Zhu; Han, Ya-Li; Liu, Yi

2016-06-01

Brown algae are well known as a source of biologically active compounds, especially those having antioxidant activities, such as phlorotannins. In this study we examined the antioxidant activities of crude phlorotannins extracts (CPEs) obtained from Sargassum hemiphyllum (SH) and fractionated according to the molecular weights. When CPEs were administrated at a dose of 30 mg/kg to Kunming mice pre-treated with carbon tetrachloride (CCl4), the levels of oxidative stress indicators in the liver, kidney and brain were significantly reduced in vivo. All the components of various molecular weight fractions of CPEs exhibited greater scavenging capacities in clearing hydroxyl free radical and superoxide anion than the positive controls gallic acid, vitamin C and vitamin E. Particularly, the components greater than 30 kD obtained from ethyl acetate phase showed the highest antioxidant capacities. These results indicated that SH is a potential source for extracting phlorotannins, the algal antioxidant compounds.

Interfacial activity of acid functionalized single-walled carbon nanotubes (SWCNTs) at the fluid-fluid interface

NASA Astrophysics Data System (ADS)

Feng, Tao; Russell, Thomas; Hoagland, David

2013-03-01

Interfacial assembly of acid-functionalized single-walled carbon nanotubes at the oil/water interface is achieved by the addition of low molecular weight (MW) amino-terminated polystyrene in the oil phase. The surface activity of carboxylated SWCNTs is strongly influenced by the end-group chemistry and molecular weight of the polystyrene component, the concentrations of this component and the SWCNTs, along with the degree of functionalization of the SWCNTs. The prerequisites for interfacial trapping are amino termini on chains with MW less than 5K and 6 hours or longer incubation of pristine SWCNTs to achieve their carboxylation. Plummets in interfacial tension resembling those for surfactants were observed at critical bulk concentrations of both SWCNTs and PS-NH2. In dried droplets, SWCNTs densely packed with associated PS-NH2 form a bird nest-like interfacial structure, with the SWCNTs preferentially oriented perpendicular to the original interface. Advisor

Analysis of low molecular weight acids by monolithic immobilized pH gradient-based capillary isoelectric focusing coupled with mass spectrometry.

PubMed

Wang, Tingting; Fekete, Agnes; Gaspar, Andras; Ma, Junfeng; Liang, Zhen; Yuan, Huiming; Zhang, Lihua; Schmitt-Kopplin, Philippe; Zhang, Yukui

2011-02-01

A novel method for the separation and detection of low molecular weight (LMW) acids was developed using monolithic immobilized pH gradient-based capillary isoelectric focusing coupled with mass spectrometry. Two main parameters, focusing conditions and delivery buffer conditions, which might affect separation efficiency, were optimized with the focusing time of 7 min at 350 V/cm and the delivery buffer of 50% (v/v) acetonitrile in 10 mmol/L ammonium formate (pH 3.0). Under these conditions, the linear correlation between the volume of delivery solvent and the pK(a) of the model components was observed. In addition, the separation mechanism of LMW acids was proposed as well. We suppose that this method may provide a useful tool for the characterization of LMW components (e.g. natural organic matter of different origins). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Resolution of molecular weight distributions in slightly pyrolyzed cellulose using the weibull function

Treesearch

A. Broido; Hsiukang Yow

1977-01-01

Even before weight loss in the low-temperature pyrolysis of cellulose becomes significant, the average degree of polymerization of the partially pyrolyzed samples drops sharply. The gel permeation chromatograms of nitrated derivatives of the samples can be described in terms of a small number of mixed size populations—each component fitted within reasonable limits by a...

Using NMR chemical shift imaging to monitor swelling and molecular transport in drug-loaded tablets of hydrophobically modified poly(acrylic acid): methodology and effects of polymer (in)solubility.

PubMed

Knöös, Patrik; Topgaard, Daniel; Wahlgren, Marie; Ulvenlund, Stefan; Piculell, Lennart

2013-11-12

A new technique has been developed using NMR chemical shift imaging (CSI) to monitor water penetration and molecular transport in initially dry polymer tablets that also contain small low-molecular weight compounds to be released from the tablets. Concentration profiles of components contained in the swelling tablets could be extracted via the intensities and chemical shift changes of peaks corresponding to protons of the components. The studied tablets contained hydrophobically modified poly(acrylic acid) (HMPAA) as the polymer component and griseofulvin and ethanol as hydrophobic and hydrophilic, respectively, low-molecular weight model compounds. The water solubility of HMPAA could be altered by titration with NaOH. In the pure acid form, HMPAA tablets only underwent a finite swelling until the maximum water content of the polymer-rich phase, as confirmed by independent phase studies, had been reached. By contrast, after partial neutralization with NaOH, the polyacid became fully miscible with water. The solubility of the polymer affected the water penetration, the polymer release, and the releases of both ethanol and griseofulvin. The detailed NMR CSI concentration profiles obtained highlighted the clear differences in the disintegration/dissolution/release behavior for the two types of tablet and provided insights into their molecular origin. The study illustrates the potential of the NMR CSI technique to give information of importance for the development of pharmaceutical tablets and, more broadly, for the general understanding of any operation that involves the immersion and ultimate disintegration of a dry polymer matrix in a solvent.

Storm impacts upon the composition of organic matrices in Nagara River--a study based on molecular weight and activated carbon adsorbability.

PubMed

Li, Fusheng; Yuasa, Akira; Chiharada, Hajime; Matsui, Yoshihiko

2003-09-01

The impacts of a heavy storm of rain on the composition of natural organic matter (NOM) in Nagara River water were studied in terms of molecular weights (MWs) and activated carbon (AC) adsorbabilities using six water samples collected during a critical Typhoon weather condition. The composition in MWs was analyzed using a HPSEC system and that in adsorbabilities was characterized using parameters devised to reflect NOMs average adsorptive strength (K(M)), adsorptive strength polydispersity (sigma), affinity to AC (1/n) and non-adsorbable fraction (C(non)/C(T0)), respectively. These parameters were determined by model description of observed isotherms with a distributed fictive component method. The heavy storm of rain brought higher content of larger organic components into the river source, thus causing changes of NOMs weight-averaged MWs in the range of 2962-3495 Dalton and MW polydispersity in the narrow range of 1.153-1.226. Comparison of K(M) and sigma values for all samples assessed with both indices of TOC and UV260 showed that large proportions of the storm-induced organic components had adsorptive strengths similar to those existent before the storm, with the presence levels for components revealing much strong and weak adsorbabilities being low. Among all organic components brought into the river by the storm of rain, the percentages of non-adsorbable ones was lower (smaller C(non)/C(T0) values); and the adsorbable ones had generally more affinity to the adsorbents used (smaller 1/n values).

Liquid chromatography-diode array detection-mass spectrometry for compositional analysis of low molecular weight heparins.

PubMed

Wang, Zhangjie; Li, Daoyuan; Sun, Xiaojun; Bai, Xue; Jin, Lan; Chi, Lianli

2014-04-15

Low molecular weight heparins (LMWHs) are important artificial preparations from heparin polysaccharide and are widely used as anticoagulant drugs. To analyze the structure and composition of LMWHs, identification and quantitation of their natural and modified building blocks are indispensable. We have established a novel reversed-phase high-performance liquid chromatography-diode array detection-electrospray ionization-mass spectrometry approach for compositional analysis of LMWHs. After being exhaustively digested and labeled with 2-aminoacridone, the structural motifs constructing LMWHs, including 17 components from dalteparin and 15 components from enoxaparin, were well separated, identified, and quantified. Besides the eight natural heparin disaccharides, many characteristic structures from dalteparin and enoxaparin, such as modified structures from the reducing end and nonreducing end, 3-O-sulfated tetrasaccharides, and trisaccharides, have been unambiguously identified based on their retention time and mass spectra. Compared with the traditional heparin compositional analysis methods, the approach described here is not only robust but also comprehensive because it is capable of identifying and quantifying nearly all components from lyase digests of LMWHs. Copyright © 2014 Elsevier Inc. All rights reserved.

Purification and properties of the hydroxylase component of methane monooxygenase

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

Patel, R.N.; Savas, J.C.

Methane monooxygenase from Methylobacterium sp. strain CRL-26 which catalyzes the oxygenation of hydrocarbons was resolved into two components, a hydroxylase and a flavoprotein. An anaerobic procedure was developed for the purification of the hydroxylase to homogeneity. The molecular weight of the hydroxylase as determined by gel filtration was 220,000, and that determined by sedimentation equilibrium analysis was about 225,000. The purified hydroxylase contained three nonidentical subunits with molecular weights of about 55,000, 40,000, and 20,000, in equal amounts as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that it is an ..cap alpha../sub 2/..beta gamma.. protein. Optical absorption spectra revealedmore » peaks near 408 and 280 nm, and fluorescence spectra revealed emission peaks at 490 and 630 nm. The purified hydroxylase contained 2.8 +/- 0.2 mol of iron and 0.5 +/- 0.1 mol of zinc per mol of protein but negligible amounts of acid-labile sulfide. The antisera prepared against the hydroxylase showed cross-reactivity with hydroxylase components in soluble extracts from other methanotrophs.« less

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

Ashraf-Khorassani, M.; Taylor, L.T.

The solubilities of 2,4,6-trinitrotoluene (TNT) and wax have been measured in supercritical carbon dioxide (Co{sub 2}) at three pressures and temperatures under static conditions. The concentrations of each component were determined off-line via ultraviolet (TNT) and evaporative light scattering (wax) detection. The solubility of TNT was an order of magnitude higher than that of wax. Gas chromatographic assay of the wax extract revealed that only the lower molecular weight components dissolved. Fractionation of the TNT and wax from an explosive material referred to as Composition B was attempted by making incremental increases in CO{sub 2} density. Composition B contains 59.5%more » cyclotrimethylene triamine (RDX), 39.5% TNT, and 1% wax. While TNT and Wax could be easily isolated from nitramine TDX, attempts to separate TNT from wax were not totally successful. More specifically, the initial fractions contained the lower molecular weight wax components in addition to major amounts of TNT. Since the percentage of TNT was approximately 50 times the amount of wax, later fractions were 100% TNT although most of the TNT was removed at the lower densities.« less

Determination of the molecular weight of low-molecular-weight heparins by using high-pressure size exclusion chromatography on line with a triple detector array and conventional methods.

PubMed

Bisio, Antonella; Mantegazza, Alessandra; Vecchietti, Davide; Bensi, Donata; Coppa, Alessia; Torri, Giangiacomo; Bertini, Sabrina

2015-03-19

The evaluation of weight average molecular weight (Mw) and molecular weight distribution represents one of the most controversial aspects concerning the characterization of low molecular weight heparins (LMWHs). As the most commonly used method for the measurement of such parameters is high performance size exclusion chromatography (HP-SEC), the soundness of results mainly depends on the appropriate calibration of the chromatographic columns used. With the aim of meeting the requirement of proper Mw standards for LMWHs, in the present work the determination of molecular weight parameters (Mw and Mn) by HP-SEC combined with a triple detector array (TDA) was performed. The HP-SEC/TDA technique permits the evaluation of polymeric samples by exploiting the combined and simultaneous action of three on-line detectors: light scattering detectors (LALLS/RALLS); refractometer and viscometer. Three commercial LMWH samples, enoxaparin, tinzaparin and dalteparin, a γ-ray depolymerized heparin (γ-Hep) and its chromatographic fractions, and a synthetic pentasaccharide were analysed by HP-SEC/TDA. The same samples were analysed also with a conventional HP-SEC method employing refractive index (RI) and UV detectors and two different chromatographic column set, silica gel and polymeric gel columns. In both chromatographic systems, two different calibration curves were built up by using (i) γ-Hep chromatographic fractions and the corresponding Mw parameters obtained via HP-SEC/TDA; (ii) the whole γ-Hep preparation with broad Mw dispersion and the corresponding cumulative distribution function calculated via HP-SEC/TDA. In addition, also a chromatographic column calibration according to European Pharmacopoeia indication was built up. By comparing all the obtained results, some important differences among Mw and size distribution values of the three LMWHs were found with the five different calibration methods and with HP-SEC/TDA method. In particular, the detection of the lower molecular weight components turned out to be the most critical aspect. Whereas HP-SEC/TDA may underestimate species under 2 KDa when present in low concentration, other methods appeared to emphasize their content.

Contrasting effects of photochemical and microbial degradation on Cu(II) binding with fluorescent DOM from different origins.

PubMed

Xu, Huacheng; Guan, Dong-Xing; Zou, Li; Lin, Hui; Guo, Laodong

2018-08-01

Effects of photochemical and microbial degradation on variations in composition and molecular-size of dissolved organic matter (DOM) from different sources (algal and soil) and the subsequent influence on Cu(II) binding were investigated using UV-Vis, fluorescence excitation-emission matrices coupled with parallel factor analysis, flow field-flow fractionation (FlFFF), and metal titration. The degradation processes resulted in an initial rapid decline in the bulk dissolved organic carbon and chromophoric and fluorescent DOM components, followed by a small or little decrease. Specifically, photochemical reaction decreased the aromaticity, humification and apparent molecular weights of all DOM samples, whereas a reverse trend was observed during microbial degradation. The FlFFF fractograms revealed that coagulation of both protein- and humic-like DOM induced an increase in molecular weights for algal-DOM, while the molecular weight enhancement for allochthonous soil samples was mainly attributed to the self-assembly of humic-like components. The Cu(II) binding capacity of algal-derived humic-like and fulvic-like DOM consistently increased during photo- and bio-degradation, while the soil-derived DOM exhibited a slight decline in Cu(II) binding capacity during photo-degradation but a substantial increase during microbial degradation, indicating source- and degradation-dependent metal binding heterogeneities. Pearson correlation analysis demonstrated that the Cu(II) binding potential was mostly related with aromaticity and molecular size for allochthonous soil-derived DOM, but was regulated by both DOM properties and specific degradation processes for autochthonous algal-derived DOM. This study highlighted the coupling role of inherent DOM properties and external environmental processes in regulating metal binding, and provided new insights into metal-DOM interactions and the behavior and fate of DOM-bound metals in aquatic environments. Copyright © 2018 Elsevier Ltd. All rights reserved.

Characteristics of liquid product from the pyrolysis of waste plastic mixture at low and high temperatures: influence of lapse time of reaction.

PubMed

Lee, Kyong-Hwan; Shin, Dae-Hyun

2007-01-01

Pyrolysis of a waste plastic mixture (high-density polyethylene: low-density polyethylene: polypropylene: polystyrene = 3:2:3:1) into a liquid product was carried out in a stirred semi-batch reactor at low (350 degrees C) and high (400 degrees C) temperatures. The effect of lapse time of reaction in the reactor and also degradation temperature on the characteristics of the liquid product from pyrolysis of the mixture was investigated. Liquid products were described by cumulative amount distribution, paraffin, olefin, naphthene and aromatic (PONA) distribution and molecular weight distribution. Their characteristic was quite differed with a lapse time of reaction and also at a low and high degradation temperatures, because of the different physicochemical properties of the plastic types in the mixture. With increase of lapse time of reaction, the order for the main products in PONA components obtained at 350 degrees C was firstly aromatic products and then olefin products, while at 400 degrees C the order was firstly aromatic products, then olefin products and finally paraffin products. The experiments also showed from the molecular weight distribution of liquid PONA components that the paraffin and olefin products had a wide distribution by mainly random scission of polymer, but in the case of olefin products were produced by an end-chain scission mechanism as well as random scission mechanism, as evidenced by much more light olefin products. This phenomenon was evident at a higher degradation temperature. Also, both the light olefin and naphthene products with a molecular weight of around 120, as a main product, showed a similar trend as a function of lapse time, which had a maximum fraction at 343 min (at 350 degrees C) and 83 min (at 400 degrees C). Among PONA components, the highest concentrations of aromatic products were obtained with a molecular weight of around 100 at the fastest lapse time of reaction, regardless of degradation temperature. It was concluded that the characteristics of liquid product on the pyrolysis of plastic mixtures were strongly influenced by lapse time of reaction and degradation temperature.

Copolymerization modification of poly (butylene itaconate)

NASA Astrophysics Data System (ADS)

Gao, Chuanhui; Wang, Jing; Han, Shijian; Hu, Zunfu; Liu, Yuetao

2017-08-01

A series of copolyesters-poly (butylene itaconate) (PBI) was synthesized by melt polycondensation from itaconic acid (IA) and 1,4-butanediol (BDO). On this basis, dimethyl terephthalate (DMT), adipic acid (AP) and sebacic acid (SA), respectively, was selected as the third comonomer component to modify PBI to poly (butylene itaconate-co-butylene terephthalate) (PBIT), poly (butylene itaconate-co-butylene adipate) (PBIA) and (butylene itaconate-co-butylene sebacate) (PBIS), of which structure and physical properties were characterized by FT-IR, 1H-NMR, GPC, DSC and TG. The results showed that PBI was amorphous material, and the molecular weight and the initial thermal decomposition temperature of PBI were 1108, 244°C, respectively. Compared to PBI, the molecular weight and the thermal stability of copolyesters (PBIA, PBIT and PBIS) could be increased by this treatment. Particularly, the molecular weight of PBIS was increased to 12,321, 12 times more than PBI, the initial thermal decomposition temperature was improved to 336°C, and PBIS had good crystallization performance.

Galloylglucoses of low molecular weight as mordant in electron microscopy. I. Procedure, and evidence for mordanting effect

PubMed Central

1976-01-01

Gallotannin, consisting mainly of low molecular weight esters such as penta- and hexagalloylglucoses (commercially available as tannic acid produced from Turkish nutgall), can be used for increasing and diversifying tissue contrast in electron microscopy. When applied on tissue specimens previously fixed by conventional methods (aldehydes and OsO4), the low molecular weight galloylglucoses (LMGG) penetrate satisfactorily the cells and induce general high contrast with fine delineation of extra- and intracellular structures, especially membranes. In some features, additional details of their intimate configuration are revealed. Various experimental conditions tested indicate that the LMGG display a complex effect on fixed tissues: they act primarily as a mordant between osmium-treated structures and lead, and concomitantly stabilize some tissue components against extraction incurred during dehydration and subsequent processing. Experiments with aldehyde blocking reagents (sodium borohydride and glycine) suggested that the LMGG mordanting effect is not dependent on residual aldehydes groups in tissues. PMID:783172

Physicochemical characteristics and biological activities of polysaccharide fractions from Phellinus baumii cultured with different methods.

PubMed

Li, Tingting; Yang, Yan; Liu, Yanfang; Zhou, Shuai; Yan, Meng Qiu; Wu, Di; Zhang, Jingsong; Tang, Chuanhong

2015-11-01

Nine polysaccharide fractions were obtained from the fruiting bodies, submerged mycelia, and solid state fermented products of Phellinus baumii using different concentrations of ethanol precipitation. The chemical characteristics and in vitro immunological activities of the nine polysaccharide fractions were compared and studied. Results indicated that the fractions precipitated with 50% ethanol had higher yields of polysaccharides and submerged mycelia contributed to high extraction yields of polysaccharides and possessed higher polysaccharide contents. HPSEC-MALLS-RI analysis showed that the molecular weight (Mw) of polysaccharide fractions from these three materials decreased with the increasing of precipitated ethanol concentration. The Mw of fruiting body polysaccharide fractions ranged from 1.98×10(4)Da to 1.89×10(6)Da. Large-molecular-weight polysaccharides (from 2.11×10(6)Da to 2.01×10(7)Da) were found in submerged mycelia. Some lower-molecular-weight polysaccharide components were found in solid fermented products. Different culture methods contributed to significant differences in monosaccharide components and molar ratios. The 50% ethanol precipitated fractions exhibited more complexity on monosaccharide compositions comparing with fractions precipitated with 30% and 70% ethanol. Polysaccharide fractions derived from submerged mycelia exhibited higher macrophages stimulation activities. Submerged culture was found to be a suitable method to prepare active polysaccharides because of its short culture span and reasonable cost. Copyright © 2015 Elsevier B.V. All rights reserved.

Enhancement of fermentable sugar yield by competitive adsorption of non-enzymatic substances from yeast and cellulase on lignin.

PubMed

Tang, Yong; Lei, Fuhou; Cristhian, Carrasco; Liu, Zuguang; Yu, Hailong; Jiang, Jianxin

2014-03-20

Enhancement of enzymatic digestibility by some supplementations could reduce enzyme loading and cost, which is still too high to realize economical production of lignocellulosic biofuels. A recent study indicates that yeast hydrolysates (YH) have improved the efficiency of cellulases on digestibility of furfural residues (FR). In the current work, the components of YH were separated by centrifugation and size exclusion chromatography and finally characterized in order to better understand this positive effect. A 60.8% of nitrogen of yeast cells was remained in the slurry (YHS) after hydrothermal treatment. In the supernatant of YH (YHL), substances of high molecular weight were identified as proteins and other UV-absorbing compounds, which showed close molecular weight to components of cellulases. Those substances attributed to a synergetic positive effect on enzymatic hydrolysis of FR. The fraction of YHL ranged from 1.19 to 2.19 mL (elution volume) contained over 50% of proteins in YHL and had the best performance in stimulating the release of glucose. Experiment results proved the adsorption of proteins in YHL on lignin. Supplementation of cellulases with YH enhances enzymatic digestibility of FR mainly by a competitive adsorption of non-enzymatic substances on lignin. The molecular weight of these substances has a significant impact on their performance. Different strategies can be used for a good utilization of yeast cells in terms of biorefinery concept.

'Ogura'-based 'CMS' lines with different nuclear backgrounds of cabbage revealed substantial diversity at morphological and molecular levels.

PubMed

Parkash, Chander; Kumar, Sandeep; Singh, Rajender; Kumar, Ajay; Kumar, Satish; Dey, Shyam Sundar; Bhatia, Reeta; Kumar, Raj

2018-01-01

A comprehensive study on characterization and genetic diversity analysis was carried out in 16 'Ogura'-based 'CMS' lines of cabbage using 14 agro-morphological traits and 29 SSR markers. Agro-morphological characterization depicted considerable variations for different horticultural traits studied. The genotype, ZHA-2, performed better for most of the economically important quantitative traits. Further, gross head weight (0.76), head length (0.60) and head width (0.83) revealed significant positive correlation with net head weight. Dendrogram based on 10 quantitative traits exhibited considerable diversity among different CMS lines and principle component analysis (PCA) indicated that net and gross head weight, and head length and width are the main components of divergence between 16 CMS lines of cabbage. In molecular study, a total of 58 alleles were amplified by 29 SSR primers, averaging to 2.0 alleles in each locus. High mean values of Shannon's Information index (0.62), expected (0.45) and observed (0.32) heterozygosity and polymorphic information content (0.35) depicted substantial polymorphism. Dendrogram based on Jaccard's similarity coefficient constructed two major groups and eight sub-groups, which revealed substantial diversity among different CMS lines. In overall, based on agro-morphological and molecular studies genotype RRMA, ZHA-2 and RCA were found most divergent. Hence, they have immense potential in future breeding programs for the high-yielding hybrid development in cabbage.

The degradation of intravenously injected chondroitin 4-sulphate in the rat

PubMed Central

Wood, Keith M.; Wusteman, Frederick S.; Curtis, C. Gerald

1973-01-01

The degradation of chondroitin 4-[35S]sulphate isolated from chick-embryo cartilage was studied in the rat by experiments on free-range animals, on wholly anaesthetized animals with ureter cannulae, by perfusion of isolated liver, by whole-body radioautography and by isolation of liver lysosomes. After injection into rats 68% of the radioactivity was recovered in the urine after 24h, approximately one-half of this being in the form of low-molecular-weight material, chiefly inorganic sulphate. Cannulation experiments demonstrated that the proportion of low-molecular-weight components excreted in the urine increased with time until, after 12h, virtually all was inorganic sulphate. Whole-body radioautography identified the liver as the major site of radioisotope accumulation after injection of labelled polysaccharide. Perfusion through isolated liver indicated that this organ has the ability to metabolize the polymer with the release of low-molecular-weight products, principally inorganic sulphate. Incubation of a lysosomal fraction prepared from rat liver after injection of chondroitin 4-[35S]sulphate gave rise to degradation products of low molecular weight, and experiments in vitro with rat liver lysosomes confirmed that these organelles are capable of the entire degradative process from chondroitin sulphate to free inorganic sulphate. ImagesPLATE 1 PMID:4762749

Probing the effect of polymer molecular weight on penetration into the wood cell wall using polyethylenimine (PEI) as a model compound.

PubMed

Dorvel, Brian; Boopalachandran, Praveenkumar; Chen, Ida; Bowling, Andrew; Williams, Kerry; King, Steve

2018-05-01

Decking is one of the largest applications for the treated wood market. The most challenging property to obtain for treated wood is dimensional stability, which can be achieved, in part, by cell wall bulking, cell wall polymer crosslinking and removal of hygroscopic components in the cell wall. A commonly accepted key requirement is for the actives to infuse through the cell wall, which has a microporosity of ∼5-13 nm. Equally as challenging is being able to measure and quantify the cell wall penetration. Branched polyethylenimine (PEI) was studied as a model polymer for penetration due to its water solubility, polarity, variable molecular weight ranges, and ability to form a chelation complex with preservative metals to treat lumbers. Two different molecular weight polyethylenimines (PEI), one with a weight average molecular weight (Mw) equal to 800 Da and the other 750 000 Da, were investigated for penetration by microscopy and spectroscopy techniques. Analytical methods were developed to both create smooth interfaces and for relative quantitation and visualisation of PEI penetration into the wood. The results showed both PEI with Mw of 800 Da and PEI with Mw of 750 000 Da coated the lumens in high density. However, only the PEI with Mw of 800 appeared to penetrate the cell walls in sufficient levels. Literature has shown the hydrodynamic radii of PEI 750 000 is near 29 nm, whereas a smaller PEI at 25 K showed 4.5 nm. Most importantly the results, based on methods developed, show how molecular weight and tertiary structure of the polymer can affect its penetration, with the microporosity of the wood being the main barrier. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

The Place for Thermoplastic Composites in Structural Components

DTIC Science & Technology

1987-12-01

The molten tube is then squashed flat and consolidated into ribbon form by continuous opposed-belt laminating. Existing graphite-epoxy pultrusion...the solid form it must have a molecular weight that exceeds the critical entanglement value. Thus thermoplastic materials of commercial worth almost

After the flood: consistency in DOM response to the 2010/2011 Australian floods

NASA Astrophysics Data System (ADS)

Shutova, Y.; Baker, A.; Bridgeman, J.; Henderson, R.

2014-12-01

The 2010/2011 floods in Eastern Australia were one of the worst on record, causing more than one billion AUD of damages and killing 35 people. This field campaign, monitoring raw water DOM concentration and character on three contrasting rivers across the region captured the late recession curve (October 2011- September 2012). DOM was characterized using fluorescence excitation-emission matrix (EEM) spectra with PARAFAC analysis; δ 13C-DOC; and molecular size using liquid chromatography with organic carbon, UV254 and nitrogen detection (LC-OCD) to identify DOC fractions: biopolymers, humic substance (HS), building blocks (BB), low molecular weight acids, and low molecular weight neutrals. Despite the difference in catchment and climatic zones, similar trends were observed in all three rivers, where DOC concentrations gradually decreased in river streams over a year from 8-11 mgCL-1 to 3-4 mgCL-1, followed by similar changes of HS, BB and fluorescent terrestrially delivered DOM components (C1-C3). In Allyn and Patterson rivers the proportion of HS, fluorescent terrestrially delivered DOM components (C1, C2) in DOC have decreased, in contrast to Logan River, where the ratio of HS/DOC was highly variable and showed no particular trends. The proportion of other DOC components remained almost the same. Molecular weight of the HS declined from 700 gmol-1 to 610 gmol-1 in all sites. δ 13C-DOC increased during monitoring, this could be linked to general decrease of DOM proportion delivered from C4 type plants after the flood. Overall, although DOC concentration decreased over the year post flood at all sites, most importantly the composition of DOM changed, with major changes occurring in proportion of humic-like and fluorescent terrestrially delivered DOM. Therefore it is important to monitor DOM character to be able to assess the impact of climate change and extreme weather events on the DOM transport and transformation.

Prostaglandins, steroids and reception (an attempt to model the structure of the active centers of adrenoreception).

PubMed

Podymov, V K; Piruzyan, L A; Gladkikh, S P; Kats, M M; Nizhnii, S V

1980-01-01

On the basis of numerous results of investigations on adrenergic systems, an orientational model of the adrenoreceptor (AR) is postulated. Its active center includes low-molecular-weight components--prostaglandins (PGE, PGF), steroids (cortisone, hydrocortisone), S+-adenosylmethionine, Ca, Mg, and Mn ions. Appraisal of the stereospecific characteristics of such a functional unit of AR explains the difference in the nature and magnitude of the effects of interaction of the catecholamines, their agonists and antagonists will the so-called alpha- and beta-AR. Depending on the organ or tissue in which the AR is located, its protein subunits comprise adenylcyclase (beta-AR) or Na,K-ATPase (alpha-AR). An obligatory component of the AR is catechol-O-methyltransferase. The model elaborated describes satisfactorily the molecular mechanisms of action of many pharmacological agents, explains why attempts to isolate and reconstruct the AR have proved fruitless, and gives grounds for rejecting the hypothesis that there exist steroid, prostaglandin, and purinergic receptors, linking the exceptionally high and diverse activity of these biologically active substances with their participation in adrenoreception among other reasons. A conception of the active centers of the AR as low-molecular-weight entities permits the explanation of such phenomena as the desensitization of the AR, the "interconversion" of beta-AR into alpha-AR with a change in the parameters of the medium, and certain components of the pathogenesis of bronchial asthma, etc.

Polycyclic aromatic hydrocarbons in sediments and mussels of Corral Bay, south central Chile.

PubMed

Palma-Fleming, Hernan; P, Adalberto J Asencio; Gutierrez, Elena

2004-03-01

PAHs were measured in sediments and mussels (Mytilus chilensis) from Carboneros and Puerto Claro, located in Corral Bay, Valdivia. According to the ratio of phenanthrene/anthracene and fluoranthene/pyrene concentrations, these sites are medium polluted with PAHs originating mainly from pyrolytic sources. Fluoranthene was the major component measured in mussels (3.1-390 ng g(-1) dry weight) and sediments (6.9-74.1 ng g(-1) dry weight). In general, mussels were mainly exposed to the dissolved fraction of the lower molecular weight PAHs (tri- and tetra-aromatics) while the higher molecular ring systems (penta- and hexa-aromatics) were more bioavailable to sediments. Mussel PAHs content was relatively constant, with the exception of the 1999 summer season (March), when higher concentration values were found in both sites; however, PAHs residues in sediments showed a temporal variation.

Coal Liquefaction desulfurization process

DOEpatents

Givens, Edwin N.

1983-01-01

In a solvent refined coal liquefaction process, more effective desulfurization of the high boiling point components is effected by first stripping the solvent-coal reacted slurry of lower boiling point components, particularly including hydrogen sulfide and low molecular weight sulfur compounds, and then reacting the slurry with a solid sulfur getter material, such as iron. The sulfur getter compound, with reacted sulfur included, is then removed with other solids in the slurry.

Multivariate analysis of mixed contaminants (PAHs and heavy metals) at manufactured gas plant site soils.

PubMed

Thavamani, Palanisami; Megharaj, Mallavarapu; Naidu, Ravi

2012-06-01

Principal component analysis (PCA) was used to provide an overview of the distribution pattern of polycyclic aromatic hydrocarbons (PAHs) and heavy metals in former manufactured gas plant (MGP) site soils. PCA is the powerful multivariate method to identify the patterns in data and expressing their similarities and differences. Ten PAHs (naphthalene, acenapthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo[a]pyrene) and four toxic heavy metals - lead (Pb), cadmium (Cd), chromium (Cr) and zinc (Zn) - were detected in the site soils. PAH contamination was contributed equally by both low and high molecular weight PAHs. PCA was performed using the varimax rotation method in SPSS, 17.0. Two principal components accounting for 91.7% of the total variance was retained using scree test. Principle component 1 (PC1) substantially explained the dominance of PAH contamination in the MGP site soils. All PAHs, except anthracene, were positively correlated in PC1. There was a common thread in high molecular weight PAHs loadings, where the loadings were inversely proportional to the hydrophobicity and molecular weight of individual PAHs. Anthracene, which was less correlated with other individual PAHs, deviated well from the origin which can be ascribed to its lower toxicity and different origin than its isomer phenanthrene. Among the four major heavy metals studied in MGP sites, Pb, Cd and Cr were negatively correlated in PC1 but showed strong positive correlation in principle component 2 (PC2). Although metals may not have originated directly from gaswork processes, the correlation between PAHs and metals suggests that the materials used in these sites may have contributed to high concentrations of Pb, Cd, Cr and Zn. Thus, multivariate analysis helped to identify the sources of PAHs, heavy metals and their association in MGP site, and thereby better characterise the site risk, which would not be possible if one uses chemical analysis alone.

Optimizing of MALDI-ToF-based low-molecular-weight serum proteome pattern analysis in detection of breast cancer patients; the effect of albumin removal on classification performance.

PubMed

Pietrowska, M; Marczak, L; Polanska, J; Nowicka, E; Behrent, K; Tarnawski, R; Stobiecki, M; Polanski, A; Widlak, P

2010-01-01

Mass spectrometry-based analysis of the serum proteome allows identifying multi-peptide patterns/signatures specific for blood of cancer patients, thus having high potential value for cancer diagnostics. However, because of problems with optimization and standardization of experimental and computational design, none of identified proteome patterns/signatures was approved for diagnostics in clinical practice as yet. Here we compared two methods of serum sample preparation for mass spectrometry-based proteome pattern analysis aimed to identify biomarkers that could be used in early detection of breast cancer patients. Blood samples were collected in a group of 92 patients diagnosed at early (I and II) stages of the disease before the start of therapy, and in a group of age-matched healthy controls (104 women). Serum specimens were purified and analyzed using MALDI-ToF spectrometry, either directly or after membrane filtration (50 kDa cut-off) to remove albumin and other large serum proteins. Mass spectra of the low-molecular-weight fraction (2-10 kDa) of the serum proteome were resolved using the Gaussian mixture decomposition, and identified spectral components were used to build classifiers that differentiated samples from breast cancer patients and healthy persons. Mass spectra of complete serum and membrane-filtered albumin-depleted samples have apparently different structure and peaks specific for both types of samples could be identified. The optimal classifier built for the complete serum specimens consisted of 8 spectral components, and had 81% specificity and 72% sensitivity, while that built for the membrane-filtered samples consisted of 4 components, and had 80% specificity and 81% sensitivity. We concluded that pre-processing of samples to remove albumin might be recommended before MALDI-ToF mass spectrometric analysis of the low-molecular-weight components of human serum Keywords: albumin removal; breast cancer; clinical proteomics; mass spectrometry; pattern analysis; serum proteome.

STUDIES ON STRUCTURAL UNITS OF THE γ-GLOBULINS

PubMed Central

Edelman, G. M.; Poulik, M. D.

1961-01-01

When human and rabbit 7S γ-globulins were reduced in strong urea solutions by a number of procedures, their molecular weights fell to approximately ⅓ of the original values. Partial separation of the reduction products was achieved using chromatography and starch gel electrophoresis in urea solutions. One of the components of reduced human 7S γ-globulin was isolated by chromatography, identified by starch gel electrophoresis, and subjected to amino acid analyses. The amino acid composition of this component differed from that of the starting material and also from that of the remaining components. A reduced pathological macroglobulin dissociated to components with an average molecular weight of 41,000. Several reduced human myeloma proteins, when subjected to starch gel electrophoresis, yielded individual patterns that nevertheless had features in common with those of reduced normal γ-globulins. Reduction of normal and abnormal γ-globulins was accompanied by the appearance of titratable sulfhydryl groups. Chemical treatments other than reduction were used to determine the type of bond holding the subunits together. It was tentatively concluded that they were linked by disulfide bonds. An hypothesis is presented to relate the structural features of the various γ-globulins in terms of the multiplicity of polypeptide chains in these molecules. PMID:13725659

Anti-Inflammatory Activity in the Low Molecular Weight Fraction of Commercial Human Serum Albumin (LMWF5A).

PubMed

Thomas, Gregory W; Rael, Leonard T; Mains, Charles W; Slone, Denetta; Carrick, Matthew M; Bar-Or, Raphael; Bar-Or, David

2016-01-01

The innate immune system is increasingly being recognized as a critical component in osteoarthritis (OA) pathophysiology. An ex vivo immunoassay utilizing human peripheral blood mononuclear cells (PBMC) was developed in order to assess the OA anti-inflammatory properties of the low molecular weight fraction (<5 kDa) of commercial human serum albumin (LMWF5A). PBMC from various donors were pre-incubated with LMWF5A before LPS stimulation. TNFα release was measured by ELISA in supernatants after an overnight incubation. A ≥ 30% decrease in TNFα release was observed. This anti-inflammatory effect is potentially useful in assessing potency of LMWF5A for the treatment of OA.

Indirect Measurement Of Nitrogen In A Multi-Component Gas By Measuring The Speed Of Sound At Two States Of The Gas.

DOEpatents

Morrow, Thomas B.; Behring, II, Kendricks A.

2004-10-12

A methods of indirectly measuring the nitrogen concentration in a gas mixture. The molecular weight of the gas is modeled as a function of the speed of sound in the gas, the diluent concentrations in the gas, and constant values, resulting in a model equation. Regression analysis is used to calculate the constant values, which can then be substituted into the model equation. If the speed of sound in the gas is measured at two states and diluent concentrations other than nitrogen (typically carbon dioxide) are known, two equations for molecular weight can be equated and solved for the nitrogen concentration in the gas mixture.

Molecular marker characterization and source appointment of particulate matter and its organic aerosols.

PubMed

Choi, Jong-Kyu; Ban, Soo-Jin; Kim, Yong-Pyo; Kim, Yong-Hee; Yi, Seung-Muk; Zoh, Kyung-Duk

2015-09-01

This study was carried out to identify possible sources and to estimate their contribution to total suspended particle (TSP) organic aerosol (OA) contents. A total of 120 TSP and PM2.5 samples were collected simultaneously every third day over a one-year period in urban area of Incheon, Korea. High concentration in particulate matters (PM) and its components (NO3(-), water soluble organic compounds (WSOCs), and n-alkanoic acids) were observed during the winter season. Among the organics, n-alkanes, n-alkanoic acids, levoglucosan, and phthalates were major components. Positive matrix factorization (PMF) analysis identified seven sources of organic aerosols including combustion 1 (low molecular weight (LMW)-polycyclic aromatic hydrocarbons (PAHs)), combustion 2 (high molecular weight (HMW)-PAHs), biomass burning, vegetative detritus (n-alkane), secondary organic aerosol 1 (SOA1), secondary organic aerosol 2 (SOA2), and motor vehicles. Vegetative detritus increased during the summer season through an increase in biogenic/photochemical activity, while most of the organic sources were prominent in the winter season due to the increases in air pollutant emissions and atmospheric stability. The correlation factors were high among the main components of the organic carbon (OC) in the TSP and PM2.5. The results showed that TSP OAs had very similar characteristics to the PM2.5 OAs. SOA, combustion (PAHs), and motor vehicle were found to be important sources of carbonaceous PM in this region. Our results imply that molecular markers (MMs)-PMF model can provide useful information on the source and characteristics of PM. Copyright © 2015 Elsevier Ltd. All rights reserved.

Utilization of non-conventional systems for conversion of biomass to food components: Recovery optimization and characterizations of algal proteins and lipids

NASA Technical Reports Server (NTRS)

Karel, M.; Nakhost, Z.

1986-01-01

Protein isolate obtained from green algae (Scenedesmus obliquus) cultivated under controlled conditions was characterized. Molecular weight determination of fractionated algal proteins using SDS-polyacrylamide gel electrophoresis revealed a wide spectrum of molecular weights ranging from 15,000 to 220,000. Isoelectric points of dissociated proteins were in the range of 3.95 to 6.20. Amino acid composition of protein isolate compared favorably with FAO standards. High content of essential amino acids leucine, valine, phenylalanine and lysine makes algal protein isolate a high quality component of closed environment life support system (CELSS) diets. To optimize the removal of algal lipids and pigments supercritical carbon dioxide extraction (with and without ethanol as a co-solvent) was used. Addition of ethanol to supercritical CO2 resulted in more efficient removal of algal lipids and produced protein isolate with a good yield and protein recovery. The protein isolate extracted by the above mixture had an improved water solubility.

Chemical signals of fish skin for the attachment response of Acanthostomum brauni cercariae.

PubMed

Haas, W; de Nuñez, M O

1988-01-01

The chemical signals of the skin surface of fish, which stimulate the attachment responses of Acanthostomum brauni cercariae, were identified by offering chemicals and fish-skin extracts in agarose substrates to the cercariae. Smaller molecules such as amino acids, fatty acids, monosaccharides, electrolytes, urea, and carbonate solutions did not stimulate attachments, but hyaluronic acid had some effects. Bovine submaxillary glycoproteins had a strong stimulating activity that disappeared after neuraminidase digestion. The stimulating components of the skin surface of fish were hydrophilic substances with molecular weights of more than 10,000. They were sensitive to neuraminidase digestion but not to hyaluronidase digestion and thus can be identified as glycoproteins. A. brauni cercariae respond only to the complete glycoprotein molecules and not to their monosaccharide components. The known attachment triggers of other cercariae are small molecules. Large glycoproteins as host signals for A. brauni cercariae may be an adaptation to muddy habitats, where various substances with low molecular weights may interfere with the host identification.

Bioremediation of coal contaminated soil under sulfate-reducing condition.

PubMed

Kuwano, Y; Shimizu, Y

2006-01-01

The objective of this study was to investigate the biodegradation of coal-derived hydrocarbons, especially high molecular weight (HMW) components, under anaerobic conditions. For this purpose biodegradation experiments were performed, using specifically designed soil column bioreactors. For the experiment, coal-contaminated soil was prepared, which contains high molecular weight hydrocarbons at high concentration (approx. 55.5 mgC g-drysoil(-1)). The experiment was carried out in two different conditions: sulfate reducing (SR) condition (SO4(2-) = 10 mmol l(-1) in the liquid medium) and control condition (SO4(2-)<0.5 mmol l(-1)). Although no degradation was observed under the control condition, the resin fraction decreased to half (from 6,541 to 3,386 mgC g-soil(-1)) under SR condition, with the concomitant increase of two PAHs (phenanthrene and fluoranthene, 9 and 2.5 times, respectively). From these results, we could conclude that high molecular hydrocarbons were biodegradable and transformed to low molecular weight PAHs under the sulfate-reducing condition. Since these PAHs are known to be biologically degraded under aerobic condition, a serial combination of anaerobic (sulfate reducing) and then aerobic bioremediations could be effective and useful for the soil pollution by petroleum and/or coal derived hydrocarbons.

Profiling analysis of low molecular weight heparins by multiple heart-cutting two dimensional chromatography with quadruple time-of-flight mass spectrometry.

PubMed

Ouyang, Yilan; Zeng, Yangyang; Rong, Yinxiu; Song, Yue; Shi, Lv; Chen, Bo; Yang, Xinlei; Xu, Naiyu; Linhardt, Robert J; Zhang, Zhenqing

2015-09-01

Low molecular weight heparins (LMWHs) are polydisperse and microheterogenous mixtures of polysaccharides used as anticoagulant drugs. Profiling analysis is important for obtaining deeper insights into the structure of LMWHs. Previous oligosaccharide mapping methods are relatively low resolution and are unable to show an entire picture of the structural complexity of LMWHs. In the current study a profiling method was developed relying on multiple heart-cutting, two-dimensional, ultrahigh performance liquid chromatography with quadruple time-of-flight mass spectrometry. This represents an efficient, automated, and robust approach for profiling LMWHs. Using size-exclusion chromatography and ion-pairing reversed-phase chromatography in a two-dimensional separation, LMW components of different sizes and LMW components of the same size but with different charges and polarities can be resolved, providing a more complete picture of a LMWH. Structural information on each component was then obtained with quadrupole time-of-flight mass spectrometry. More than 80 and 120 oligosaccharides were observed and unambiguously assigned from the LMWHs, nadroparin and enoxaparin, respectively. This method might be useful for quality control of LMWHs and as a powerful tool for heparin-related glycomics.

Thermochemolysis: A New Sample Preparation Approach for the Detection of Organic Components of Complex Macromolecules in Mars Rocks via Gas Chromatography Mass Spectrometry in SAM on MSL

NASA Technical Reports Server (NTRS)

Eugenbrode, J.; Glavin, D.; Dworkin, J.; Conrad, P.; Mahaffy, P.

2011-01-01

Organic chemicals, when present in extraterrestrial samples, afford precious insight into past and modern conditions elsewhere in the Solar System . No single technology identifies all molecular components because naturally occurring molecules have different chemistries (e.g., polar vs. non-polar, low to high molecular weight) and interface with the ambient sample chemistry in a variety of modes (i.e., organics may be bonded, absorbed or trapped by minerals, liquids, gases, or other organics). More than 90% of organic matter in most natural samples on Earth and in meteorites is composed of complex macromolecules (e.g. biopolymers, complex biomolecules, humic substances, kerogen) because the processes that tend to break down organic molecules also tend towards complexation of the more recalcitrant components. Thus, methodologies that tap the molecular information contained within macromolecules may be critical to detecting extraterrestrial organic matter and assessing the sources and processes influencing its nature.

A two-dimensional spectrum analysis for sedimentation velocity experiments of mixtures with heterogeneity in molecular weight and shape.

PubMed

Brookes, Emre; Cao, Weiming; Demeler, Borries

2010-02-01

We report a model-independent analysis approach for fitting sedimentation velocity data which permits simultaneous determination of shape and molecular weight distributions for mono- and polydisperse solutions of macromolecules. Our approach allows for heterogeneity in the frictional domain, providing a more faithful description of the experimental data for cases where frictional ratios are not identical for all components. Because of increased accuracy in the frictional properties of each component, our method also provides more reliable molecular weight distributions in the general case. The method is based on a fine grained two-dimensional grid search over s and f/f (0), where the grid is a linear combination of whole boundary models represented by finite element solutions of the Lamm equation with sedimentation and diffusion parameters corresponding to the grid points. A Monte Carlo approach is used to characterize confidence limits for the determined solutes. Computational algorithms addressing the very large memory needs for a fine grained search are discussed. The method is suitable for globally fitting multi-speed experiments, and constraints based on prior knowledge about the experimental system can be imposed. Time- and radially invariant noise can be eliminated. Serial and parallel implementations of the method are presented. We demonstrate with simulated and experimental data of known composition that our method provides superior accuracy and lower variance fits to experimental data compared to other methods in use today, and show that it can be used to identify modes of aggregation and slow polymerization.

Recovering the Physical Properties of Molecular Gas in Galaxies from CO SLED Modeling

NASA Astrophysics Data System (ADS)

Kamenetzky, J.; Privon, G. C.; Narayanan, D.

2018-05-01

Modeling of the spectral line energy distribution (SLED) of the CO molecule can reveal the physical conditions (temperature and density) of molecular gas in Galactic clouds and other galaxies. Recently, the Herschel Space Observatory and ALMA have offered, for the first time, a comprehensive view of the rotational J = 4‑3 through J = 13‑12 lines, which arise from a complex, diverse range of physical conditions that must be simplified to one, two, or three components when modeled. Here we investigate the recoverability of physical conditions from SLEDs produced by galaxy evolution simulations containing a large dynamical range in physical properties. These simulated SLEDs were generally fit well by one component of gas whose properties largely resemble or slightly underestimate the luminosity-weighted properties of the simulations when clumping due to nonthermal velocity dispersion is taken into account. If only modeling the first three rotational lines, the median values of the marginalized parameter distributions better represent the luminosity-weighted properties of the simulations, but the uncertainties in the fitted parameters are nearly an order of magnitude, compared to approximately 0.2 dex in the “best-case” scenario of a fully sampled SLED through J = 10‑9. This study demonstrates that while common CO SLED modeling techniques cannot reveal the underlying complexities of the molecular gas, they can distinguish bulk luminosity-weighted properties that vary with star formation surface densities and galaxy evolution, if a sufficient number of lines are detected and modeled.

Enhancement of fermentable sugar yield by competitive adsorption of non-enzymatic substances from yeast and cellulase on lignin

PubMed Central

2014-01-01

Background Enhancement of enzymatic digestibility by some supplementations could reduce enzyme loading and cost, which is still too high to realize economical production of lignocellulosic biofuels. A recent study indicates that yeast hydrolysates (YH) have improved the efficiency of cellulases on digestibility of furfural residues (FR). In the current work, the components of YH were separated by centrifugation and size exclusion chromatography and finally characterized in order to better understand this positive effect. Results A 60.8% of nitrogen of yeast cells was remained in the slurry (YHS) after hydrothermal treatment. In the supernatant of YH (YHL), substances of high molecular weight were identified as proteins and other UV-absorbing compounds, which showed close molecular weight to components of cellulases. Those substances attributed to a synergetic positive effect on enzymatic hydrolysis of FR. The fraction of YHL ranged from 1.19 to 2.19 mL (elution volume) contained over 50% of proteins in YHL and had the best performance in stimulating the release of glucose. Experiment results proved the adsorption of proteins in YHL on lignin. Conclusions Supplementation of cellulases with YH enhances enzymatic digestibility of FR mainly by a competitive adsorption of non-enzymatic substances on lignin. The molecular weight of these substances has a significant impact on their performance. Different strategies can be used for a good utilization of yeast cells in terms of biorefinery concept. PMID:24650152

Mirrored continuum and molecular scale simulations of the ignition of high-pressure phases of RDX

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

Lee, Kibaek; Stewart, D. Scott, E-mail: santc@illinois.edu, E-mail: dss@illinois.edu; Joshi, Kaushik

2016-05-14

We present a mirrored atomistic and continuum framework that is used to describe the ignition of energetic materials, and a high-pressure phase of RDX in particular. The continuum formulation uses meaningful averages of thermodynamic properties obtained from the atomistic simulation and a simplification of enormously complex reaction kinetics. In particular, components are identified based on molecular weight bin averages and our methodology assumes that both the averaged atomistic and continuum simulations are represented on the same time and length scales. The atomistic simulations of thermally initiated ignition of RDX are performed using reactive molecular dynamics (RMD). The continuum model ismore » based on multi-component thermodynamics and uses a kinetics scheme that describes observed chemical changes of the averaged atomistic simulations. Thus the mirrored continuum simulations mimic the rapid change in pressure, temperature, and average molecular weight of species in the reactive mixture. This mirroring enables a new technique to simplify the chemistry obtained from reactive MD simulations while retaining the observed features and spatial and temporal scales from both the RMD and continuum model. The primary benefit of this approach is a potentially powerful, but familiar way to interpret the atomistic simulations and understand the chemical events and reaction rates. The approach is quite general and thus can provide a way to model chemistry based on atomistic simulations and extend the reach of those simulations.« less

Large Soluble Oligomers of Amyloid β-Protein from Alzheimer Brain Are Far Less Neuroactive Than the Smaller Oligomers to Which They Dissociate

PubMed Central

Yang, Ting; Li, Shaomin; Xu, Huixin

2017-01-01

Soluble oligomers of amyloid β-protein (oAβ) isolated from the brains of Alzheimer's disease (AD) patients have been shown experimentally (in the absence of amyloid plaques) to impair hippocampal synaptic plasticity, decrease synapses, induce tau hyperphosphorylation and neuritic dystrophy, activate microglial inflammation, and impair memory in normal adult rodents. Nevertheless, there has been controversy about what types of oligomers actually confer these AD-like phenotypes. Here, we show that the vast majority of soluble Aβ species obtained from brains of humans who died with confirmed AD elute at high molecular weight (HMW) on nondenaturing size-exclusion chromatography. These species have little or no cytotoxic activity in several bioassays. However, incubation of HMW oAβ in mildly alkaline buffer led to their quantitative dissociation into low molecular weight oligomers (∼8–70 kDa), and these were now far more bioactive: they impaired hippocampal LTP, decreased neuronal levels of β2-adrenergic receptors, and activated microglia in wt mice in vivo. Thus, most soluble Aβ assemblies in AD cortex are large and inactive but under certain circumstances can dissociate into smaller, highly bioactive species. Insoluble amyloid plaques likely sequester soluble HMW oligomers, limiting their potential to dissociate. We conclude that conditions that destabilize HMW oligomers or retard the sequestration of their smaller, more bioactive components are important drivers of Aβ toxicity. Selectively targeting these small, cytotoxic forms should be therapeutically beneficial. SIGNIFICANCE STATEMENT Oligomers of amyloid β-protein (oAβ) are tought to play an important role in Alzheimer's disease (AD), but there is confusion and controversy about what types and sizes of oligomers have disease-relevant activity. Using size-exclusion chromatography and three distinct measures of bioactivity, we show that the predominant forms of Aβ in aqueous extracts of AD brain are high molecular weight (HMW) and relatively inactive. Importantly, under certain conditions, the abundant HMW oAβ can dissociate into low molecular weight species, and these low molecular weight oligomers are significantly more bioactive on synapses and microglia than the HMW species from which they are derived. We conclude that conditions that destabilize HMW oAβ or retard the sequestration of smaller, more bioactive components are important drivers of Aβ toxicity. PMID:28053038

Effect of molecular weight and concentration of hyaluronan on cell proliferation and osteogenic differentiation in vitro

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

Zhao, Ningbo, E-mail: curl-zhao@163.com; Wang, Xin, E-mail: 394041230@qq.com; Qin, Lei, E-mail: qinlei30@126.com

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 bymore » 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.« less

Top-down and bottom-up analysis of commercial enoxaparins.

PubMed

Liu, Xinyue; St Ange, Kalib; Lin, Lei; Zhang, Fuming; Chi, Lianli; Linhardt, Robert J

2017-01-13

A strategy for the comprehensive analysis of low molecular weight (LMW) heparins is described that relies on using an integrated top-down and bottom-up approach. Liquid chromatography-mass spectrometry, an essential component of this approach, is rapid, robust, and amenable to automated processing and interpretation. Nuclear magnetic resonance spectroscopy provides complementary top-down information on the chirality of the uronic acid residues comprising a low molecular weight heparin. Using our integrated approach four different low molecular weight heparins prepared from porcine heparin through chemical β-eliminative cleavage were comprehensively analyzed. Lovenox™ and Clexane™, the innovator versions of enoxaparin marketed in the US and Europe, respectively, and two generic enoxaparins, from Sandoz and Teva, were analyzed. The results which were supported by analysis of variation (ANOVA), while showing remarkable similarities between different versions of the product and good lot-to-lot consistency of each product, also detects subtle differences that may result from differences in their manufacturing processes or differences in the source (or parent) porcine heparin from which each product is prepared. Copyright © 2016 Elsevier B.V. All rights reserved.

Cu-catalyzed multicomponent polymerization to synthesize a library of poly(N-sulfonylamidines).

PubMed

Lee, In-Hwan; Kim, Hyunseok; Choi, Tae-Lim

2013-03-13

We report a versatile Cu-catalyzed multicomponent polymerization (MCP) technique that enables the synthesis of high-molecular-weight, defect-free poly(N-sulfonylamidines) from monomers of diynes, sulfonyl azides, and diamines. Through a series of optimizations, we discovered that the addition of excess triethylamine and the use of N,N'-dimethylformamide as a solvent are key factors to ensure efficient MCP. Formation of cyclic polyamidines was a side reaction during polymerization, but it was readily controlled by using diynes or diamines with long or rigid moieties. In addition, this polymerization is highly selective for three-component reactions over click reactions. The combination of the above factors enables the synthesis of high-molecular-weight polymers, which was challenging in previous MCPs. All three kinds of monomers (diynes, sulfonyl azides, and diamines) are readily accessible and stable under the reaction conditions, with various monomers undergoing successful polymerization regardless of their steric and electronic properties. Thus, we synthesized various high-molecular-weight, defect-free polyamidines from a broad range of monomers while overcoming the limitations of previous MCPs, such as low conversion and defects in the polymer structures.

Changes of the Components of Fresh Seaweed, Undaria pinnatifida, by Different Strage Conditions

NASA Astrophysics Data System (ADS)

Onodera, Munenaka; Yoshie-Stark, Yumiko; Suzuki, Takesh

This study was performed to keep the quality and to prolong the shelf life of fresh Undaria pinnatifida, by different storage conditions. Changes of the contents of chlorophyll a (Chl a) and its derivatives, β-carotene, pH, molecular weight of alginate and molecular weight distribution were determined during the storage of U. pinnatifida. The conditions of cold storage at -3 to 7°C with air or O2, storage in seawater, and storage in slurry ice made of seawater were tested. Chl a and β-carotene contents, and the pH of U. pinnatifida were decreased following the increment of storage days. Significant decrease of Chl a content and molecular weight of U. pinnatifida was detected under cold storage especially at 7°C. The storage by icing in slurry ice and by super chilling at -3°C inhibited the degradation of Chl a and β-carotene of U. pinnatifida. The content of pheophorbide a or pH were recognized as useful factors to evaluate the quality and freshness of U. pinnatifida.

Black Carbon in Estuarine and Coastal Ocean Dissolved Organic Matter

NASA Technical Reports Server (NTRS)

Mannino, Antonio; Harvey, H. Rodger

2003-01-01

Analysis of high-molecular-weight dissolved organic matter (DOM) from two estuaries in the northwest Atlantic Ocean reveals that black carbon (BC) is a significant component of previously uncharacterized DOM, suggesting that river-estuary systems are important exporters of recalcitrant dissolved organic carbon to the ocean.

21 CFR 177.1440 - 4,4′-Isopropylidenediphenol-epichlorohydrin resins minimum molecular weight 10,000.

Code of Federal Regulations, 2014 CFR

2014-04-01

... ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1440 4,4... articles intended for use in producing, manufacturing, packing, processing, preparing, treating, packaging...

Carbohydrate composition of mature and immature faba bean (Vicia faba L.) seeds from diverse origins

USDA-ARS?s Scientific Manuscript database

Faba bean (Vicia faba L.) is a valuable pulse crop for human consumption. The low molecular weight carbohydrates (LMWC): glucose, fructose, sucrose (GFS), raffinose, stachyose, and verbascose (RFO- raffinose family oligosaccharides) in faba bean seeds are significant components of human nutrition an...

Inferential determination of various properties of a gas mixture

DOEpatents

Morrow, Thomas B.; Behring, II, Kendricks A.

2007-03-27

Methods for inferentially determining various properties of a gas mixture, when the speed of sound in the gas is known at an arbitrary temperature and pressure. The method can be applied to natural gas mixtures, where the known parameters are the sound speed, temperature, pressure, and concentrations of any dilute components of the gas. The method uses a set of reference gases and their calculated density and speed of sound values to estimate the density of the subject gas. Additional calculations can be made to estimate the molecular weight of the subject gas, which can then be used as the basis for heating value calculations. The method may also be applied to inferentially determine density and molecular weight for gas mixtures other than natural gases.

Correlation between phosphorylation level of a hippocampal 86kDa protein and extinction of a behaviour in a model of Wernicke-Korsakoff syndrome.

PubMed

Pires, Rita G W; Pereira, Sílvia R C; Carvalho, Fabiana M; Oliveira-Silva, Ieda F; Ferraz, Vany P; Ribeiro, Angela M

2007-06-04

The effects of chronic ethanol and thiamine deficiency, alone or associated, on hippocampal protein phosphorylation profiles ranging in molecular weight from 30 to 250kDa molecular weight, in stimulated (high K(+) concentration) and unstimulated (basal) conditions were investigated. These treatments significantly changed the phosphorylation level of an 86kDa phosphoprotein. Thiamine deficiency, but not chronic ethanol, induced a decrease in a behavioural extinction index, which is significantly correlated to the phosphorylation level of the p86 protein. These data add to and extend previous findings by our laboratory implicating the involvement of hippocampal neurotransmission components in extinction of a behaviour which involves learning of environmental spatial cues.

Characteristics and DBP formation of dissolved organic matter from leachates of fresh and aged leaf litter.

PubMed

Jian, Qianyun; Boyer, Treavor H; Yang, Xiuhong; Xia, Beicheng; Yang, Xin

2016-06-01

Dissolved organic matter (DOM) was leached from leaves of two trees commonly grown in subtropical regions, Pinus elliottii (commonly known as slash pine) and Schima superba (S. superba), and its degradation pattern and potential for forming disinfection byproducts (DBPs) were evaluated. The leaves were exposed in the field for up to one year before leaching. The DOM leached from slash pine litter contained on average 10.4 mg of dissolved organic carbon (DOC) per gram of dry weight; for S. superba the average was 37.2 mg-DOC/g-dry weight. Ultraviolet and visible light absorbance, fluorescence, and molecular weight analysis indicated that more aromatic/humic and higher molecular weight compounds are formed as leaf litter ages. A 4-component parallel factor analysis of the fluorescence data showed that the intensity of peaks related with protein-like components decreased gradually during biodegradation, while that of peaks attributed to humic-acid-like components increased continuously. Fresh slash pine leachates formed on average 40.0 μg of trihalomethane (THM) per milligram of DOC, while S. superba leachates formed 45.6 μg. THM formation showed peak values of 55.7 μg/mg DOC for slash pine and 74.9 μg/mg DOC for S. superba after 8 months of aging. The formation of haloacetonitrile (HAN) and trichloronitromethane (TCNM) increased with increasing leaf age, while chloral hydrate (CH) formation did not show such a trend. Specific UV absorbance showed some positive correlation with DBPs, but humic-acid-like and protein-like absorbance peaks correlated with CH and TCNM yields in only some leaf samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mirrored continuum and molecular scale simulations of the ignition of gamma phase RDX

NASA Astrophysics Data System (ADS)

Stewart, D. Scott; Chaudhuri, Santanu; Joshi, Kaushik; Lee, Kibaek

2017-01-01

We describe the ignition of an explosive crystal of gamma-phase RDX due to a thermal hot spot with reactive molecular dynamics (RMD), with first-principles trained, reactive force field based molecular potentials that represents an extremely complex reaction network. The RMD simulation is analyzed by sorting molecular product fragments into high and low molecular weight groups, to represent identifiable components that can be interpreted by a continuum model. A continuum model based on a Gibbs formulation has a single temperature and stress state for the mixture. The continuum simulation that mirrors the atomistic simulation allows us to study the atomistic simulation in the familiar physical chemistry framework and provides an essential, continuum/atomistic link.

The putative serine protease inhibitor Api m 6 from Apis mellifera venom: recombinant and structural evaluation.

PubMed

Michel, Y; McIntyre, M; Ginglinger, H; Ollert, M; Cifuentes, L; Blank, S; Spillner, E

2012-01-01

Immunoglobulin (Ig) E-mediated reactions to honeybee venom can cause severe anaphylaxis, sometimes with fatal consequences. Detailed knowledge of the allergic potential of all venom components is necessary to ensure proper diagnosis and treatment of allergy and to gain a better understanding of the allergological mechanisms of insect venoms. Our objective was to undertake an immunochemical and structural evaluation of the putative low-molecular-weight serine protease inhibitor Api m 6, a component of honeybee venom. We recombinantly produced Api m 6 as a soluble protein in Escherichia coli and in Spodoptera frugiperda (Sf9) insect cells.We also assessed specific IgE reactivity of venom-sensitized patients with 2 prokaryotically produced Api m 6 variants using enzyme-linked immunosorbent assay. Moreover, we built a structural model ofApi m 6 and compared it with other protease inhibitor structures to gain insights into the function of Api m 6. In a population of 31 honeybee venom-allergic patients, 26% showed specific IgE reactivity with prokaryotically produced Api m 6, showing it to be a minor but relevant allergen. Molecular modeling of Api m 6 revealed a typical fold of canonical protease inhibitors, supporting the putative function of this venom allergen. Although Api m 6 has a highly variant surface charge, its epitope distribution appears to be similar to that of related proteins. Api m 6 is a honeybee venom component with IgE-sensitizing potential in a fraction of venom-allergic patients. Recombinant Api m 6 can help elucidate individual component-resolved reactivity profiles and increase our understanding of immune responses to low-molecular-weight allergens

Development of a nanofiltration method for bone collagen 14C AMS dating

NASA Astrophysics Data System (ADS)

Boudin, Mathieu; Boeckx, Pascal; Buekenhoudt, Anita; Vandenabeele, Peter; Van Strydonck, Mark

2013-01-01

Radiocarbon dating of bones is usually performed on the collagen fraction. However, this collagen can contain exogenous molecules, including humic substances (HSs) and/or other soil components that may have a different age than the bone. Incomplete removal can result in biased 14C dates. Ultrafiltration of collagen, dissolved as gelatin (molecular weight (MW) ∼100,000 Dalton), has received considerable attention to obtain more reliable dates. Ultrafiltration is an effective method of removal of low-molecular weight contaminants from bone collagen but it does not remove high-molecular weight contaminants, such as cross-linked humic collagen complexes. However, comparative dating studies have raised the question whether this cleaning step itself may introduce contamination with carbon from the filters used. In this study, a nanofiltration method was developed using a ceramic filter to avoid a possible extraneous carbon contamination introduced by the filter. This method should be applicable to various protein materials e.g. collagen, silk, wool, leather and should be able to remove low-molecular and high molecular weight HSs. In this study bone collagen was hot acid hydrolyzed to amino acids and nanofiltrated. A filter with a molecular weight cutoff (MWCO) of 450 Dalton was chosen in order to collect the amino acids in the permeate and the HSs in the retentate. Two pilot studies were set up. Two nanofiltration types were tested in pilot study 1: dead end and cross flow filtration. Humic substance (HS)-solutions with fossil carbon and modern hydrolyzed collagen contaminated with HSs were filtrated and analyzed with spectrofluorescence to determine the HS removal. Cross flow nanofiltration showed the most efficient HS removal. A second pilot study based upon these results was set up wherein only cross flow filtration was performed. 14C measurements of the permeates of hydrolyzed modern collagen contaminated with fossil HSs demonstrate a significant but incomplete removal of HSs (between 63% and 85%).

Chemicals derived from pyrolysis bio-oils as antioxidants in fuels and lubricants

USDA-ARS?s Scientific Manuscript database

Softwood and hardwood lignins and hardwood were pyrolyzed to produce bio-oils to produce lignin-derived bio-oils of which phenols were the major component. These bio-oils were extracted with alkali to yield a range of lignin-related phenols having molecular weights (MWs) from 110 to 344. When tested...

Calculating the permeability coefficients of mixed matrix membranes of polydimethylsiloxane and silicalite crystals to various ethanol-water solutions using molecular simulations.

EPA Science Inventory

The permeability coefficients of mixed matrix membranes of polydimethylsiloxane (PDMS) and silicalite crystal are taken as the sum of the permeability coefficients of membrane components each weighted by their associated mass fraction. The permeability coefficient of a membrane c...

Low-molecular-weight lignin-rich fraction in the extract of cultured Lentinula edodes mycelia attenuates carbon tetrachloride-induced toxicity in primary cultures of rat hepatocytes.

PubMed

Yoshioka, Yasuko; Kojima, H; Tamura, A; Tsuji, K; Tamesada, M; Yagi, K; Murakami, N

2012-01-01

The extract of cultured Lentinula edodes mycelia (LEM) is a medicinal food ingredient that has hepatoprotective effects. In this study, we fractionated the LEM extract to explore novel active compounds related to hepatoprotection by using primary cultures of rat hepatocytes exposed to carbon tetrachloride (CCl(4)). The LEM extract and the fractions markedly inhibited the release of alanine aminotransferase (ALT) from hepatocytes damaged by CCl(4) into the culture medium. The strongest hepatocyte-protective activity was seen in a fraction (Fr. 2) in which a 50% ethanol extract was further eluted with 50% methanol and separated using reverse-phase HPLC. Fr. 2 had an average molecular weight of 2753, and the main components are lignin (49%) and saccharides (36%, of which xylose comprises 41%). Therefore, Fr. 2 was presumed to be a low-molecular-weight compound consisting mainly of lignin and xylan-like polysaccharides. The hepatocyte-protective activity was observed even after digestion of xylan-like polysaccharides in Fr.2 and confirmed with low-molecular-weight lignin (LM-lignin) alone. In addition, Fr. 2, the xylan-digested Fr. 2 and LM-lignin showed higher superoxide dismutase (SOD)-like activity than the LEM extract. These results suggested that the effective fraction in the LEM extract related to hepatocyte protection consisted mainly of LM-lignin, and its antioxidant activity partially contributes to the hepatocyte-protective activity of the LEM extract.

Studies on a lipopolysaccharide-protein complex from Yersinia pseudotuberculosis. 1 isolation and characterization.

PubMed

Solov'eva, T F; Yermak, I M; Bondarenko, O D; Frolova, G M; Ovodov, Y S

1979-01-01

A comparative study of various procedures of a lipopolysaccharide-protein complex (LPPC) from Yersinia pseudotuberculosis was carried out. The materials obtained were fractionated by molecular-sieve chromatography on Sepharose 2B resulting in highly aggregated complexes with antigen activity. LPPC aggregates dissociated in the presence of sodium dodecylsulphate (SDS) and urea. The chemical composition and serologic properties of fractions obtained are under consideration. The protein component of the complex consists of two major polypeptides (molecular weights--45,000 and 20,000) and some minor ones. The LPS component appeared to give 2--3 narrow bands in gel under conditions of SDS-polyacrylamide gel electrophoresis. It is suggested that such fractionation is caused by LPS association-dissociation in the course of electrophoresis.

Prediction of frozen food properties during freezing using product composition.

PubMed

Boonsupthip, W; Heldman, D R

2007-06-01

Frozen water fraction (FWF), as a function of temperature, is an important parameter for use in the design of food freezing processes. An FWF-prediction model, based on concentrations and molecular weights of specific product components, has been developed. Published food composition data were used to determine the identity and composition of key components. The model proposed in this investigation had been verified using published experimental FWF data and initial freezing temperature data, and by comparison to outputs from previously published models. It was found that specific food components with significant influence on freezing temperature depression of food products included low molecular weight water-soluble compounds with molality of 50 micromol per 100 g food or higher. Based on an analysis of 200 high-moisture food products, nearly 45% of the experimental initial freezing temperature data were within an absolute difference (AD) of +/- 0.15 degrees C and standard error (SE) of +/- 0.65 degrees C when compared to values predicted by the proposed model. The predicted relationship between temperature and FWF for all analyzed food products provided close agreements with experimental data (+/- 0.06 SE). The proposed model provided similar prediction capability for high- and intermediate-moisture food products. In addition, the proposed model provided statistically better prediction of initial freezing temperature and FWF than previous published models.

Pheromone production, male abundance, body size, and the evolution of elaborate antennae in moths

PubMed Central

Symonds, Matthew RE; Johnson, Tamara L; Elgar, Mark A

2012-01-01

The males of some species of moths possess elaborate feathery antennae. It is widely assumed that these striking morphological features have evolved through selection for males with greater sensitivity to the female sex pheromone, which is typically released in minute quantities. Accordingly, females of species in which males have elaborate (i.e., pectinate, bipectinate, or quadripectinate) antennae should produce the smallest quantities of pheromone. Alternatively, antennal morphology may be associated with the chemical properties of the pheromone components, with elaborate antennae being associated with pheromones that diffuse more quickly (i.e., have lower molecular weights). Finally, antennal morphology may reflect population structure, with low population abundance selecting for higher sensitivity and hence more elaborate antennae. We conducted a phylogenetic comparative analysis to test these explanations using pheromone chemical data and trapping data for 152 moth species. Elaborate antennae are associated with larger body size (longer forewing length), which suggests a biological cost that smaller moth species cannot bear. Body size is also positively correlated with pheromone titre and negatively correlated with population abundance (estimated by male abundance). Removing the effects of body size revealed no association between the shape of antennae and either pheromone titre, male abundance, or mean molecular weight of the pheromone components. However, among species with elaborate antennae, longer antennae were typically associated with lower male abundances and pheromone compounds with lower molecular weight, suggesting that male distribution and a more rapidly diffusing female sex pheromone may influence the size but not the general shape of male antennae. PMID:22408739

Host responses and metabolic profiles of wood components in Dutch elm hybrids with a contrasting tolerance to Dutch elm disease

PubMed Central

Ďurkovič, Jaroslav; Kačík, František; Olčák, Dušan; Kučerová, Veronika; Krajňáková, Jana

2014-01-01

Background and Aims Changes occurring in the macromolecular traits of cell wall components in elm wood following attack by Ophiostoma novo-ulmi, the causative agent of Dutch elm disease (DED), are poorly understood. The purpose of this study was to compare host responses and the metabolic profiles of wood components for two Dutch elm (Ulmus) hybrids, ‘Groeneveld’ (a susceptible clone) and ‘Dodoens’ (a tolerant clone), that have contrasting survival strategies upon infection with the current prevalent strain of DED. Methods Ten-year-old plants of the hybrid elms were inoculated with O. novo-ulmi ssp. americana × novo-ulmi. Measurements were made of the content of main cell wall components and extractives, lignin monomer composition, macromolecular traits of cellulose and neutral saccharide composition. Key Results Upon infection, medium molecular weight macromolecules of cellulose were degraded in both the susceptible and tolerant elm hybrids, resulting in the occurrence of secondary cell wall ruptures and cracks in the vessels, but rarely in the fibres. The 13C nuclear magnetic resonance spectra revealed that loss of crystalline and non-crystalline cellulose regions occurred in parallel. The rate of cellulose degradation was influenced by the syringyl:guaiacyl ratio in lignin. Both hybrids commonly responded to the medium molecular weight cellulose degradation with the biosynthesis of high molecular weight macromolecules of cellulose, resulting in a significant increase in values for the degree of polymerization and polydispersity. Other responses of the hybrids included an increase in lignin content, a decrease in relative proportions of d-glucose, and an increase in proportions of d-xylose. Differential responses between the hybrids were found in the syringyl:guaiacyl ratio in lignin. Conclusions In susceptible ‘Groeneveld’ plants, syringyl-rich lignin provided a far greater degree of protection from cellulose degradation than in ‘Dodoens’, but only guaiacyl-rich lignin in ‘Dodoens’ plants was involved in successful defence against the fungus. This finding was confirmed by the associations of vanillin and vanillic acid with the DED-tolerant ‘Dodoens’ plants in a multivariate analysis of wood traits. PMID:24854167

Host responses and metabolic profiles of wood components in Dutch elm hybrids with a contrasting tolerance to Dutch elm disease.

PubMed

Durkovič, Jaroslav; Kačík, František; Olčák, Dušan; Kučerová, Veronika; Krajňáková, Jana

2014-07-01

Changes occurring in the macromolecular traits of cell wall components in elm wood following attack by Ophiostoma novo-ulmi, the causative agent of Dutch elm disease (DED), are poorly understood. The purpose of this study was to compare host responses and the metabolic profiles of wood components for two Dutch elm (Ulmus) hybrids, 'Groeneveld' (a susceptible clone) and 'Dodoens' (a tolerant clone), that have contrasting survival strategies upon infection with the current prevalent strain of DED. Ten-year-old plants of the hybrid elms were inoculated with O. novo-ulmi ssp. americana × novo-ulmi. Measurements were made of the content of main cell wall components and extractives, lignin monomer composition, macromolecular traits of cellulose and neutral saccharide composition. Upon infection, medium molecular weight macromolecules of cellulose were degraded in both the susceptible and tolerant elm hybrids, resulting in the occurrence of secondary cell wall ruptures and cracks in the vessels, but rarely in the fibres. The (13)C nuclear magnetic resonance spectra revealed that loss of crystalline and non-crystalline cellulose regions occurred in parallel. The rate of cellulose degradation was influenced by the syringyl:guaiacyl ratio in lignin. Both hybrids commonly responded to the medium molecular weight cellulose degradation with the biosynthesis of high molecular weight macromolecules of cellulose, resulting in a significant increase in values for the degree of polymerization and polydispersity. Other responses of the hybrids included an increase in lignin content, a decrease in relative proportions of d-glucose, and an increase in proportions of d-xylose. Differential responses between the hybrids were found in the syringyl:guaiacyl ratio in lignin. In susceptible 'Groeneveld' plants, syringyl-rich lignin provided a far greater degree of protection from cellulose degradation than in 'Dodoens', but only guaiacyl-rich lignin in 'Dodoens' plants was involved in successful defence against the fungus. This finding was confirmed by the associations of vanillin and vanillic acid with the DED-tolerant 'Dodoens' plants in a multivariate analysis of wood traits. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Bifidobacterium breve C50 secretes lipoprotein with CHAP domain recognized in aggregated form by TLR2.

PubMed

Scuotto, Angelo; Djorie, Serge; Colavizza, Michel; Romond, Pierre-Charles; Romond, Marie-Bénédicte

2014-12-01

Extracellular components secreted by Bifidobacterium breve C50 can induce maturation, high IL-10 production and prolonged survival of dendritic cells via a TLR2 pathway. In this study, the components were isolated from the supernatant by gel filtration chromatography. Antibodies raised against the major compounds with molecular weight above 600 kDa (Bb C50BC) also recognized compounds of lower molecular weight (200–600 kDa). TLR2 and TLR6 bound to the components already recognized by the antibodies. Trypsin digestion of Bb C50BC released three major peptides whose sequences displayed close similarities to a putative secreted protein with a CHAP amidase domain from B. breve. The 1300-bp genomic region corresponding to the hypothetical protein was amplified by PCR. The deduced polypeptide started with an N-terminal signal sequence of 45 amino acids, containing the lipobox motif (LAAC) with the cysteine in position 25, and 2 positively charged residues within the first 14 residues of the signal sequence. Lipid detection in Bb C50BC by GC/MS further supported the implication of a lipoprotein. Sugars were also detected in Bb C50BC. Close similarity with the glucan-binding protein B from Bifidobacterium animalis of two released peptides from Bb C50BC protein suggested that glucose moieties, possibly in glucan form, could be bound to the lipoprotein. Finally, heating at 100 °C for 5 min led to the breakdown of Bb C50BC in compounds of molecular weight below 67 kDa, which suggested that Bb C50BC was an aggregate. One might assume that a basic unit was formed by the lipoprotein bound putatively to glucan. Besides the other sugars and hexosamines recognized by galectin 1 were localized at the surface of the Bb C50BC aggregate. In conclusion, the extracellular components secreted by B. breve C50 were constituted of a lipoprotein putatively associated with glucose moieties and acting in an aggregating form as an agonist of TLR2/TLR6.

Analytical Approaches to Understanding the Role of Non-carbohydrate Components in Wood Biorefinery

NASA Astrophysics Data System (ADS)

Leskinen, Timo Ensio

This dissertation describes the production and analysis of wood subjected to a novel electron beam-steam explosion pretreatment (EB-SE) pretreatment with the aim to evaluate its suitability for the production of bioethanol. The goal of these studies was to: 1) develop analytical methods for the investigation of depolymerization of wood components under pretreatments, 2) analyze the effects of EB-SE pretreatment on the pretreated biomass, 3) define how lignin and extractive components affect the action of enzymes on cellulosic substrates, and 4) examine how changes in lignin structure impact its isolation and potential conversion into value added chemicals. The first section of the work describes the development of a size-exclusion chromatography (SEC) methodology for molecular weight analysis for native and pretreated wood. The selective analysis of carbohydrates and lignin from native wood was made possible by the combination of two selective derivatization methods, ionic liquid assisted benzoylation of the carbohydrate fraction and acetobromination of the lignin in acetic acid media. This method was then used to examine changes in softwood samples after the EB-SE pretreatment. The methodology was shown to be effective for monitoring changes in the molecular weight profiles of the pretreated wood. The second section of the work investigates synergistic effects of the EB-SE pretreatment on the molecular level structures of wood components and the significance of these alterations in terms of enzymatic digestibility. The two pretreatment steps depolymerized cell wall components in different fashion, while showing synergistic effects. Hardwood and softwood species responded differently to similar treatment conditions, which was attributed to the well-known differences in the structure of their lignin and hemicellulose fractions. The relatively crosslinked lignin in softwood appeared to limit swelling and subsequent depolymerization in comparison to hardwood. Additional studies revealed that an insoluble, likely crosslinked, lignin fraction induced enzyme inhibition, while soluble lower molecular weight fractions were slightly beneficial for the enzymatic hydrolysis of cellulose. The third section of the work addresses the influence of hydrophobic wood extractives and representative model compounds on the cellulolytic hydrolysis of cellulosic substrates. Deposition of specific fractions of isolated wood extractives on cellulose was found either to enhance or inhibit the action of cellulase enzymes, depending on the chemical nature of the fraction. Using model compounds this effect was found to be correlated with the compounds chemical structure, and underlying mechanisms could be rationalized by Hansen solubility parameter considerations. The amphiphilic and hydrophobic nature of the model extractives was found to influence the deposition of extractives on the cellulose surfaces, and the adsorption of cellulolytic enzymes, as measured with Quartz Crystal Microgravimetry. Beneficial effects of the extractives were likely related to reduction in the irreversible binding of the enzymes on the cellulose substrate. The fourth section of the work deals with the recovery of lignin using extraction methods based on aqueous alkali or aqueous ethanol. The objective of this study was to understand how the yield, MW and structure of lignin recovered from the process residue was impacted by the different isolation methods. Mild extraction conditions allowed for recovery of approximately 40 wt.% of the lignin present in the process residues. Base or acid catalyzed hydrolysis of the lignin could increase the recovery lignin yield to about 76 wt.%. The recovered lignins were characterized in terms of their functional groups, molecular weights and thermal properties. The lignins from mild alkali and ethanol extractions showed similarities in their chemical profiles while, as expected, the hydrolyzed lignins were different and depended on the hydrolysis conditions. The molecular weight and thermal properties of the lignin products were affected by the applied isolation process.

Effects of inhaled high-molecular weight hyaluronan in inflammatory airway disease.

PubMed

Lamas, Adelaida; Marshburn, Jamie; Stober, Vandy P; Donaldson, Scott H; Garantziotis, Stavros

2016-10-03

Cystic fibrosis (CF) is a chronic inflammatory disease that is affecting thousands of patients worldwide. Adjuvant anti-inflammatory treatment is an important component of cystic fibrosis treatment, and has shown promise in preserving lung function and prolonging life expectancy. Inhaled high molecular weight hyaluronan (HMW-HA) is reported to improve tolerability of hypertonic saline and thus increase compliance, and has been approved in some European countries for use as an adjunct to hypertonic saline treatment in cystic fibrosis. However, there are theoretical concerns that HMW-HA breakdown products may be pro-inflammatory. In this clinical pilot study we show that sputum cytokines in CF patients receiving HMW-HA are not increased, and therefore HMW-HA does not appear to adversely affect inflammatory status in CF airways.

Mobile-bearing knee systems: ultra-high molecular weight polyethylene wear and design issues.

PubMed

Greenwald, A Seth; Heim, Christine S

2005-01-01

In June 2004, the U.S. Food and Drug Administration Orthopaedic Advisory Panel recommended the reclassification of mobile-bearing knee systems for general use. This reflects the increasing use of mobile-bearing knee systems internationally, which is currently limited in the United States by regulatory requirement. Mobile-bearing knee systems are distinguished from conventional, fixed-plateau systems in that they allow dual-surface articulation between an ultra-high molecular weight polyethylene insert and metallic femoral and tibial tray components. Their in vivo success is dependent on patient selection, design, and material choice, as well as surgical precision during implantation. Laboratory and clinical experience extending over 25 years with individual systems suggests that mobile-bearing knee systems represent a viable treatment option for patients with knee arthrosis.

Molecular weight analyses and enzymatic degradation profiles of the soft-tissue fillers Belotero Balance, Restylane, and Juvéderm Ultra.

PubMed

Flynn, Timothy Corcoran; Thompson, David H; Hyun, Seok-Hee

2013-10-01

In this study, the authors sought to determine the molecular weight distribution of three hyaluronic acids-Belotero Balance, Restylane, and Juvéderm Ultra-and their rates of degradation following exposure to hyaluronidase. Lot consistency of Belotero Balance also was analyzed. Three lots of Belotero Balance were analyzed using liquid chromatography techniques. The product was found to have high-molecular-weight and low-molecular-weight species. One lot of Belotero Balance was compared to one lot each of Juvéderm Ultra and Restylane. Molecular weights of the species were analyzed. The hyaluronic acids were exposed to ovine testicular hyaluronidase at six time points-baseline and 0.5, 1, 2, 6, and 24 hours-to determine degradation rates. Belotero Balance lots were remarkably consistent. Belotero Balance had the largest high-molecular-weight species, followed by Juvéderm Ultra and Restylane (p < 0.001). Low-molecular-weight differences among all three hyaluronic acids were not statistically significant. Percentages of high-molecular-weight polymer differ among the three materials, with Belotero Balance having the highest fraction of high-molecular-weight polymer. Degradation of the high-molecular-weight species over time showed different molecular weights of the high-molecular-weight fraction. Rates of degradation of the hyaluronic acids following exposure to ovine testicular hyaluronidase were similar. All hyaluronic acids were fully degraded at 24 hours. Fractions of high-molecular-weight polymer differ across the hyaluronic acids tested. The low-molecular-weight differences are not statistically significant. The high-molecular-weight products have different molecular weights at the 0.5- and 2-hour time points when exposed to ovine testicular hyaluronidase and are not statistically different at 24 hours.

The Role of Molecular Weight and Temperature on the Elastic and Viscoelastic Properties of a Glassy Thermoplastic Polyimide

NASA Technical Reports Server (NTRS)

Nicholson, Lee M.; Whitley, Karen S.; Gates, Thomas S.

2001-01-01

Mechanical testing of the elastic and viscoelastic response of an advanced thermoplastic polyimide (LaRC-SI) with known variations in molecular weight was performed over a range of temperatures below the glass transition temperature. The notched tensile strength was shown to be a strong function of both molecular weight and temperature, whereas stiffness was only a strong function of temperature. A critical molecular weight was observed to occur at a weight average molecular weight of M, approx. 22,000 g/mol below which, the notched tensile strength decreases rapidly. This critical molecular weight transition is temperature-independent. Low, molecular weight materials tended to fail in a brittle manner, whereas high molecular weight materials exhibited ductile failure. Furthermore, low molecular weight materials have increased creep compliance and creep compliance rate, and are more sensitive to temperature than the high molecular weight materials. At long timescales (less than 1100 hours) physical aging serves to significantly decrease the creep compliance and creep rate of all the materials tested. Low molecular weight materials are less influenced by the effects of physical aging.

Diffusion blotting: a rapid and simple method for production of multiple blots from a single gel.

PubMed

Olsen, Ingrid; Wiker, Harald G

2015-01-01

A very simple and fast method for diffusion blotting of proteins from precast SDS-PAGE gels on a solid plastic support was developed. Diffusion blotting for 3 min gives a quantitative transfer of 10 % compared to 1-h electroblotting. For each subsequent blot from the same gel a doubling of transfer time is necessary to obtain the same amount of protein onto each blot. High- and low-molecular-weight components are transferred equally efficiently when compared to electroblotting. However, both methods do give a higher total transfer of the low-molecular-weight proteins compared to the large proteins. The greatest advantage of diffusion blotting is that several blots can be made from each lane, thus enabling testing of multiple antisera on virtually identical blots. The gel remains on the plastic support, which prevents it from stretching or shrinking. This ensures identical blots and facilitates more reliable molecular weight determination. Furthermore the proteins remaining in the gel can be stained with Coomassie Brilliant Blue or other methods for exact and easy comparison with the developed blots. These advantages make diffusion blotting the method of choice when quantitative protein transfer is not required.

The relative safety of gamma-ray, autoclave, and ethylene oxide gas sterilization of thermosetting polyurethane.

PubMed

Shintani, H

1995-01-01

Sterilization of polyurethane (PU) produces 4,4'-methylenedianiline (MDA), a known carcinogen, and various other compounds. The relationships of the components of PU to the formation of these compounds by sterilization were studied. Specimens of PU fabricated from different combinations of isocyanates and polyols were obtained from dialyzers. The molecular weight of the particular polyol was found to influence the production of MDA by sterilization. Sterilization also produced many unidentified compounds. MDA production was not always associated with the production of the other compounds. Compared with gamma-ray irradiation and ethylene oxide gas (EOG) sterilization, autoclave sterilization eluted more hydrophilic compounds. This phenomenon was significant for PUs produced from smaller-molecular-weight polyols. The combination of autoclave sterilization and a PU produced from a larger-molecular-weight polyol is recommended to minimize the production of potentially toxic compounds. Of the techniques studied, EOG sterilization produced the least amounts of MDA and the other compounds, but the residue of EOG is itself problematic. The risk posed by the amounts of MDA extracted was not significant, but the biological safety of the other compounds remains to be determined.

Modified pectic polysaccharide from turmeric (Curcuma longa): A potent dietary component against gastric ulcer.

PubMed

Harsha, Mysore R; Chandra Prakash, Serkad V; Dharmesh, Shylaja M

2016-03-15

Native, intact (TrPP) and modified, low-molecular-weight (MTrPP) forms of pectic polysaccharides isolated from turmeric were evaluated for ulcer-preventive potentials in in vitro and in vivo models. Data indicated that MTrPP possessed significantly better ulcer-preventive property than TrPP; inhibiting ulcer scores up to 85%. Results were substantiated by effective muco-protection, H(+),K(+)-ATPase down-regulation, inhibition of H. pylori growth/adherence, higher antioxidant/cytoprotective mechanisms. Structural data indicated TrPP and MTrPP differ in their molecular weights and structural characteristics with different sugar compositions and side chain ratios. MTrPP was rich in galacturonic acid (687mg/g; TrPP-544mg/g) and galactose (52.9%; TrPP-21.7%). Results were substantiated by NMR/FTIR data indicating the presence of homogalacturonan and rhamnogalacturonam-I containing galactans. By virtue of binding to inflammatory marker (galectin-3), galactans may reduce inflammation induced ulcerations. The low molecular weight of MTrPP (155kDa; TrPP-13kDa) may increase its bioavailability than TrPP, thus MTrPP may possess higher antiulcer potential. Copyright © 2015 Elsevier Ltd. All rights reserved.

Concentration and fractionation of hydrophobic organic acid constituents from natural waters by liquid chromatography

USGS Publications Warehouse

Thurman, E.M.; Malcolm, R.L.

1979-01-01

A scheme is presented which used adsorption chromatography with pH gradient elution and size-exclusion chromatography to concentrate and separate hydrophobic organic acids from water. A review of chromatographic processes involved in the flow scheme is also presented. Organic analytes which appear in each aqueous fraction are quantified by dissolved organic carbon analysis. Hydrophobic organic acids in a water sample are concentrated on a porous acrylic resin. These acids usually constitute approximately 30-50 percent of the dissolved organic carbon in an unpolluted water sample and are eluted with an aqueous eluent (dilute base). The concentrate is then passed through a column of polyacryloylmorpholine gel, which separates the acids into high- and low-molecular-weight fractions. The high- and low-molecular-weight eluates are reconcentrated by adsorption chromatography, then are eluted with a pH gradient into strong acids (predominately carboxylic acids) and weak acids (predominately phenolic compounds). For standard compounds and samples of unpolluted waters, the scheme fractionates humic substances into strong and weak acid fractions that are separated from the low molecular weight acids. A new method utilizing conductivity is also presented to estimate the acidic components in the methanol fraction.

Influence of Molecular Weight on the Mechanical Performance of a Thermoplastic Glassy Polyimide

NASA Technical Reports Server (NTRS)

Nicholson, Lee M.; Whitley, Karen S.; Gates, Thomas S.; Hinkley, Jeffrey A.

1999-01-01

Mechanical Testing of an advanced thermoplastic polyimide (LaRC-TM-SI) with known variations in molecular weight was performed over a range of temperatures below the glass transition temperature. The physical characterization, elastic properties and notched tensile strength were all determined as a function of molecular weight and test temperature. It was shown that notched tensile strength is a strong function of both temperature and molecular weight, whereas stiffness is only a strong function of temperature. A critical molecular weight (Mc) was observed to occur at a weight-average molecular weight (Mw) of approx. 22000 g/mol below which, the notched tensile strength decreases rapidly. This critical molecular weight transition is temperature-independent. Furthermore, inelastic analysis showed that low molecular weight materials tended to fail in a brittle manner, whereas high molecular weight materials exhibited ductile failure. The microstructural images supported these findings.

Influence of gamma-irradiation sterilization and temperature on the fracture toughness of ultra-high-molecular-weight polyethylene.

PubMed

Pascaud, R S; Evans, W T; McCullagh, P J; FitzPatrick, D P

1997-05-01

Surface damage of the tibial plateau components of knee prostheses made from medical grade ultra-high-molecular-weight polyethylene (UHMW-PE) has been attributed to delamination wear caused by a fatigue fracture mechanism. It has been proposed that factors such as component design and method of sterilization contribute to such failure mechanisms. Understanding the fracture behaviour of UHMW-PE is therefore critical in optimizing the in vivo life-span of total joint components. The elastic-plastic fracture toughness parameter J was consequently determined for a commercial UHMW-PE at ambient and body temperatures, before and after gamma-irradiation sterilization in air at a minimum dose of 29 kGy. Both ductile stability theory and experimental data suggest that cracks propagate in a stable manner, although stability is affected by the sterilization process. Sterilization with gamma-irradiation results in a loss in fracture toughness JIc of 50% and a decrease in tearing modulus (Tm) of 30%. This dramatic reduction could result in a 50% decrease in the residual strength of the components, maximum permissible crack size under service loading and service life (assuming flaws such as fusion defects exist). The time required for a crack to grow from its original size to the maximum permissible size could be decreased by 30%, resulting in earlier failure. In terms of the design of joint replacement components the critical factor to envisage is the design stress level, which should be halved to account for the irradiation process. A scanning electron microscope study reveals that the material fails in layers parallel to the fracture surface.

Comparison of optical properties of chromophoric dissolved organic matter (CDOM) in alpine lakes above or below the tree line: insights into sources of CDOM.

PubMed

Su, Yaling; Chen, Feizhou; Liu, Zhengwen

2015-05-01

Here we investigated absorption and fluorescence properties of chromophoric dissolved organic matter (CDOM) in 15 alpine lakes located below or above the tree line to determine its source and composition. The results indicate that the concentrations of CDOM in below-tree-line lakes are significantly higher than in above-tree-line lakes, as evidenced from the absorption coefficients of a250 and a365. The intensities of the protein-like and humic-like fluorescence in below-tree-line lakes are higher than in above-tree-line lakes as well. Three fluorescent components were identified using parallel factor analysis (PARAFAC) modelling. Component 1 is probably associated with biological degradation of terrestrial humic component. The terrestrial humic-like component 2 is only found in below-tree-line lakes. The protein-like or phenolic component 3 is dominant in above-tree-line lakes, which is probably more derived from autochthonous origin. In this study, (1) higher a250/a365 and S275-295 values indicate smaller molecular weights of CDOM in above-tree-line lakes than in below-tree-line lakes, and smaller molecular weights at the surface than at 2.0 m depth; (2) SUVA254 and FI255 results provide evidence of lower percent aromaticity of CDOM in above-tree-line lakes; and (3) FI310 and FI370 suggest a strong allochthonous origin at the surface in below-tree-line lakes, and more contribution from autochthonous biological and aquatic bacterial origin in above-tree-line lakes.

Novel "omics" approach for study of low-abundance, low-molecular-weight components of a complex biological tissue: regional differences between chorionic and basal plates of the human placenta.

PubMed

Kedia, Komal; Nichols, Caitlin A; Thulin, Craig D; Graves, Steven W

2015-11-01

Tissue proteomics has relied heavily on two-dimensional gel electrophoresis, for protein separation and quantification, then single protein isolation, trypsin digestion, and mass spectrometric protein identification. Such methods are predominantly used for study of high-abundance, full-length proteins. Tissue peptidomics has recently been developed but is still used to study the most highly abundant species, often resulting in observation and identification of dozens of peptides only. Tissue lipidomics is likewise new, and reported studies are limited. We have developed an "omics" approach that enables over 7,000 low-molecular-weight, low-abundance species to be surveyed and have applied this to human placental tissue. Because the placenta is believed to be involved in complications of pregnancy, its proteomic evaluation is of substantial interest. In previous research on the placental proteome, abundant, high-molecular-weight proteins have been studied. Application of large-scale, global proteomics or peptidomics to the placenta have been limited, and would be challenging owing to the anatomic complexity and broad concentration range of proteins in this tissue. In our approach, involving protein depletion, capillary liquid chromatography, and tandem mass spectrometry, we attempted to identify molecular differences between two regions of the same placenta with only slightly different cellular composition. Our analysis revealed 16 species with statistically significant differences between the two regions. Tandem mass spectrometry enabled successful sequencing, or otherwise enabled chemical characterization, of twelve of these. The successful discovery and identification of regional differences between the expression of low-abundance, low-molecular weight biomolecules reveals the potential of our approach.

HDL2-cholesterol/HDL3-cholesterol ratio was associated with insulin resistance, high-molecular-weight adiponectin, and components for metabolic syndrome in Japanese.

PubMed

Moriyama, Kengo; Negami, Masako; Takahashi, Eiko

2014-11-01

Recent data have suggested a relationship between the high-density lipoprotein (HDL) subclass ratio and metabolic syndrome (MetS). However, limited information is available regarding the relationships between the HDL subclass ratio and insulin resistance, associated adipocytokine levels, and MetS components. The associations of the high-density lipoprotein 2 cholesterol (HDL2-C) to high-density lipoprotein 3 cholesterol (HDL3-C) ratio with the homeostasis model assessment of insulin resistance (HOMA-IR) index, high-molecular-weight adiponectin (HMW-Ad) levels, and MetS components were examined. The study included 1155 Japanese subjects who met our inclusion criteria and underwent an annual health examination that included an HDL subclass analysis. The HDL2-C/HDL3-C ratio and the HMW-Ad level gradually decreased as the number of MetS components increased. In contrast, HOMA-IR gradually increased as the number of MetS components increased. The HDL2-C/HDL3-C ratio correlated inversely with HOMA-IR and positively with the HMW-Ad level. A strong positive correlation was observed between the HDL2-C/HDL3-C ratio and the HDL-C level. The HDL2-C/HDL3-C ratio exhibited moderate negative correlations with the body mass index, waist circumference, and triglyceride level. Weak negative correlations were observed for the HDL2-C/HDL3-C ratio with the systolic and diastolic blood pressure and fasting plasma glucose levels. Our data indicated that the HDL2-C/HDL3-C ratio was associated with insulin resistance, the HMW-Ad level, and MetS components, and it was useful for evaluating MetS in Japanese individuals. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Irradiated Benzene Ice Provides Clues to Meteoritic Organic Chemistry

NASA Technical Reports Server (NTRS)

Callahan, Michael Patrick; Gerakines, Perry Alexander; Martin, Mildred G.; Hudson, Reggie L.; Peeters, Zan

2013-01-01

Aromatic hydrocarbons account for a significant portion of the organic matter in carbonaceous chondrite meteorites, as a component of both the low molecular weight, solvent-extractable compounds and the insoluble organic macromolecular material. Previous work has suggested that the aromatic compounds in carbonaceous chondrites may have originated in the radiation-processed icy mantles of interstellar dust grains. Here we report new studies of the organic residue made from benzene irradiated at 19 K by 0.8 MeV protons. Polyphenyls with up to four rings were unambiguously identified in the residue by gas chromatography-mass spectrometry. Atmospheric pressure photoionization Fourier transform mass spectrometry was used to determine molecular composition, and accurate mass measurements suggested the presence of polyphenyls, partially hydrogenated polyphenyls, and other complex aromatic compounds. The profile of low molecular weight compounds in the residue compared well with extracts from the Murchison and Orgueil meteorites. These results are consistent with the possibility that solid phase radiation chemistry of benzene produced some of the complex aromatics found in meteorites.

Purification and characterization of Aspergillus niger exo-1,4-glucosidase.

PubMed

Freedberg, I M; Levin, Y; Kay, C M; McCubbin, W D; Katchalski-Katzir, E

1975-06-24

A specific exo-1,4-glucosidase (1,4-alpha-D-glucan glucohydrooase, EC 3.2.1.3) from Aspergillus niger has been partially purified and subsequently characterized by biochemical, physico-chemical and optical methods. Molecular sieve chromatography yields an enzyme with maximal activity at pH 4.2-4.5 close to its isoelectric point. Reduction and carboxymethylation leads to complete loss of activity and O-acetylation of 3 of the 13 tyrosine residues results in loss of 20 % of the activity. Sodium dodecylsulfate-polyacrylamide gel electrophoresis indicates that the native enzyme consists of two major components of molecular weights 63 000 and 57 500, respectively. Small amounts of dissociated material of molecular weight 28 000 and 16 000 as well as aggregates of the order of 100 000 are also present to the extent of 2-5% of the total potein. Following reduction and carboxymethylation under forcing conditions, the bands around 60 000 diminish and the 28 000-30 000, 16 000 and aggregate bands are dominant...

Evidence of intralocus recombination at the Glu-3 loci in bread wheat (Triticum aestivum L.)

USDA-ARS?s Scientific Manuscript database

The low-molecular weight glutenin subunits (LMW-GSs) are one of the major components of wheat seed storage proteins and play a critical role in the determination of wheat flour bread-making quality. The genes encoding for this class of proteins are mainly located at the orthologous Glu-3 loci (Glu-A...

Effects of water deficit on breadmaking quality and storage protein compositions in bread wheat (Triticum aestivum L.).

PubMed

Zhou, Jiaxing; Liu, Dongmiao; Deng, Xiong; Zhen, Shoumin; Wang, Zhimin; Yan, Yueming

2018-03-12

Water deficiency affects grain proteome dynamics and storage protein compositions, resulting in changes in gluten viscoelasticity. In this study, the effects of field water deficit on wheat breadmaking quality and grain storage proteins were investigated. Water deficiency produced a shorter grain-filling period, a decrease in grain number, grain weight and grain yield, a reduced starch granule size and increased protein content and glutenin macropolymer contents, resulting in superior dough properties and breadmaking quality. Reverse phase ultra-performance liquid chromatography analysis showed that the total gliadin and glutenin content and the accumulation of individual components were significantly increased by water deficiency. Two-dimensional gel electrophoresis detected 144 individual storage protein spots with significant accumulation changes in developing grains under water deficit. Comparative proteomic analysis revealed that water deficiency resulted in significant upregulation of 12 gliadins, 12 high-molecular-weight glutenin subunits and 46 low-molecular-weight glutenin subunits. Quantitative real-time polymerase chain reaction analysis revealed that the expression of storage protein biosynthesis-related transcription factors Dof and Spa was upregulated by water deficiency. The present results illustrated that water deficiency leads to increased accumulation of storage protein components and upregulated expression of Dof and Spa, resulting in an improvement in glutenin strength and breadmaking quality. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

[Immunochemical study of the proteins of various tissues in Crustacea (Decapoda): nature, role, origin].

PubMed

Durliat, M

1983-11-01

The main proteins of the haemolymph of Crustacea Decapoda have been identified and analysed: haemocyanin, plasma coagulogen, heteroagglutinins, vitellogenins, and molt-related proteins. All these complex components exhibit a high molecular weight and as oligomeric fractions are able to aggregate or dissociate in subunits according to the composition of medium and experimental procedures. Besides their important rôle in the defense mechanism, some proteins are involved in the edification of diverse tissues. They are detected within different compartments: soft integument, calcified carapace and hepatopancreas. They are either in transit or sequestered or synthetized within these tissues. In the crayfish Astacus leptodactylus, some components have been identified in different compartments: --in aqueous extracts from soft integument: the haemocyanin, coagulogen and both fraction F1 (lipoprotein with an approximate molecular weight of 45 kdal) and fraction F2 related to the molt. Both coagulogen and fraction F2 appear sometimes as melanized. These two latter fractions exhibit some glucose-mannose residues and they occur with a higher relative amount than in the blood. --in soluble extracts from calcified cuticle: among the numerous fractions showing a high molecular weight, the haemocyanin and coagulogen are detected. --in aqueous extracts from hepatopancreas: both haemocyanin and coagulogen appear with a little relative amount. Components termed as Fa and Fb are found with a high concentration. One minor fraction is also detected. --in aqueous extracts from eggs: the haemocyanin and fraction Fb are present. Other proteins showing only some antigenic identities with those of the haemolymph are also detected in all these tissues. The haemolymph proteins are not present within these compartments following a passive diffusion. Indeed, their relative amount varies according to the tissue investigated and is different from that found in the blood. Except the haemocyanin detected in all tissues with different aggregation states, the haemolymph proteins identified vary in the organs studied. A qualitative and quantitative selection occurs when the blood proteins enter the other compartments. Perhaps some other proteins are not detected following alterations underwent either in the epithelial barriers or during the tannage process or the chitino-proteic complex formation or due to experimental procedures. On the other hand, each tissue has its own proteins. The integument contains crustacyanins alpha, beta, gamma; the eggs are mainly constituted of lipovitellins and the hepatopancreas is rich in small molecular weight proteins and digestive enzymes.(ABSTRACT TRUNCATED AT 400 WORDS)

Evaluation of Isolated Fractions of Aloe vera Gel Materials on Indinavir Pharmacokinetics: In vitro and in vivo Studies.

PubMed

Wallis, Lonette; Malan, Maides; Gouws, Chrisna; Steyn, Dewald; Ellis, Suria; Abay, Efrem; Wiesner, Lubbe; Otto, Daniel P; Hamman, Josias

2016-01-01

Aloe vera is a plant with a long history of traditional medicinal use and is consumed in different products, sometimes in conjunction with prescribed medicines. A. vera gel has shown the ability to modulate drug absorption in vitro. The aim of this study was to fractionate the precipitated polysaccharide component of A. vera gel based on molecular weight and to compare their interactions with indinavir pharmacokinetics. Crude polysaccharides were precipitated from a solution of A. vera gel and was fractionated by means of centrifugal filtration through membranes with different molecular weight cut-off values (i.e. 300 KDa, 100 KDa and 30 KDa). Marker molecules were quantified in the aloe leaf materials by means of nuclear magnetic resonance spectroscopy and the average molecular weight was determined by means of gel filtration chromatography linked to multi-angle-laser-light scattering and refractive index detection. The effect of the aloe leaf materials on the transepithelial electrical resistance (TEER) of Caco-2 cell monolayers as well as indinavir metabolism in LS180 cells was measured. The bioavailability of indinavir in the presence and absence of the aloe leaf materials was determined in Sprague-Dawley rats. All the aloe leaf materials investigated in this study reduced the TEER of Caco-2 cell monolayers, inhibited indinavir metabolism in LS 180 cells to different extents and changed the bioavailability parameters of indinavir in rats compared to that of indinavir alone. These indinavir pharmacokinetic modulation effects were not dependent on the presence of aloverose and also not on the average molecular weight of the isolated fractions.

Ultraviolet-B radiation mobilizes uranium from uranium-dissolved organic carbon complexes in aquatic systems, demonstrated by asymmetrical flow field-flow fractionation.

PubMed

Nehete, Sachin Vilas; Christensen, Terje; Salbu, Brit; Teien, Hans-Christian

2017-05-05

Humic substances have a tendency to form complexes with metal ions in aquatic medium, impacting the metal mobility, decreasing bioavailability and toxicity. Ultraviolet-B (UV-B) radiation exposure degrades the humic substance, changes their molecular weight distribution and their metal binding capacity in aquatic medium. In this study, we experimented the effect of UV-B radiation on the uranium complexed with fulvic acids and humic acids in a soft water system at different pH, uranium concentrations and radiant exposure. The concentration and distribution of uranium in a complexed form were investigated by asymmetrical flow field-flow fractionation coupled to multi detection technique (AsFlFFF-UV-ICP-MS). The major concentration of uranium present in complexes was primarily associated with average and higher molecular weight fulvic and humic acids components. The concentration of uranium in a complexed form increased with increasing fulvic and humic acid concentrations as well as pH of the solution. The higher molecular weight fraction of uranium was degraded due to the UV-B exposure, transforming about 50% of the uranium-dissolved organic carbon complexes into low molecular weight uranium species in complex form with organic ligands and/or free form. The result also suggests AsFlFFF-UV-ICP-MS to be an important separation and detection technique for understanding the interaction of radionuclides with dissolved organic matter, tracking size distribution changes during degradation of organic complexes for understanding mobility, bioavailability and ecosystem transfer of radionuclides as well as metals. Copyright © 2017 Elsevier B.V. All rights reserved.

[Search for potential gastric cancer biomarkers using low molecular weight blood plasma proteome profiling by mass spectrometry].

PubMed

Shevchenko, V E; Arnotskaia, N E; Ogorodnikova, E V; Davydov, M M; Ibraev, M A; Turkin, I N; Davydov, M I

2014-01-01

Gastric cancer, one of the most widespread malignant tumors, still lacks reliable serum/plasma biomarkers of its early detection. In this study we have developed, unified, and tested a new methodology for search of gastric cancer biomarkers based on profiling of low molecular weight proteome (LMWP) (1-17 kDa). This approach included three main components: sample pre-fractionation, matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS), data analysis by a bioinformatics software package. Applicability and perspectives of the developed approach for detection of potential gastric cancer markers during LMWP analysis have been demonstrated using 69 plasma samples from patients with gastric cancer (stages I-IV) and 238 control samples. The study revealed peptides/polypeptides, which may be potentially used for detection of this pathology.

Degradation of Lignin by Cyathus Species

PubMed Central

Abbott, Thomas P.; Wicklow, Donald T.

1984-01-01

The ability of 12 Cyathus species to degrade 14C-labeled lignin in kenaf was studied. The sum of 14C released into solution plus 14C released into the gas phase over a 32-day fermentation period was used to determine average daily rates of lignin biodegradation. Cyathus pallidus. C. africanus, and C. berkeleyanus delignified kenaf most rapidly. C. canna showed the greatest preference for lignin degradation over other plant components, and its rate of lignin degradation was only slightly lower than the three most active species. The apparent ability of fungi to metabolize low-molecular-weight lignin breakdown products correlated well with their overall delignification rates. C. stercoreus metabolized degradation products of lignin from wheat straw better than those from kenaf lignin, based on the amount of low-molecular-weight products left in solution. PMID:16346497

[Isolation and characterization of active compounds from Aloe vera with a possible role in skin protection].

PubMed

Kostálová, D; Bezáková, L; Oblozinský, M; Kardosová, A

2004-09-01

Aloe vera is widely used in food supplements, beverages, pharmaceuticals, and cosmetics. It has been long recognized as an effective natural remedy for its wound-healing properties and its positive influence on other inflammatory skin disorders. Major proteins and mono- and polysaccharides were identified and analysed from Aloe vera commercial extract. Molecular weight of proteins calculated from the sets of molecular weight reference standards, ranged from 70 kDa for the largest to 14 kDa for the smallest ones. IR spectral analysis of the carbohydrate fraction shows that the main carbohydrate copound is acetylated (1 --> 4)-beta-D-mannan substituated with D-galactose and D-glucose. The results have shown that proteins and polysaccharides are a necessary component in the study of biological activity of Aloe vera leaf extract.

A STUDY OF THE COMPONENTS OF THE CORNIFIED EPITHELIUM OF HUMAN SKIN

PubMed Central

Matoltsy, A. Gedeon; Balsamo, Constance A.

1955-01-01

Pulverized cornified epithelium of human skin was divided into a "soluble fraction" and a "residue." About half of the "soluble fraction" proved to be soluble epidermal keratin (keratin A); the remainder, dialyzable substances of low molecular weight. The "residue" contained epidermal keratin and resistant cell membranes of cornified cells. Epidermal keratin was found to form an oriented and dense submicroscopic structure in the cornified cells. It showed high resistance toward strong acid and moderately strong alkali solutions as well as concentrated urea. In strong alkali, reducing substances, alkaline urea, and mixtures of reducing substance with alkali, epidermal keratin dissociated and yielded a non-dialyzable derivative of high molecular weight (keratin B) which resembled true proteins. The cell membranes of cornified cells showed higher resistance toward strong alkali and reducing substance than did epidermal keratin. PMID:13242598

Scanning Electron Microscopy and Energy-Dispersive X-Ray Spectroscopy as a Valuable Tool to Investigate the Ultra-High-Molecular-Weight Polyethylene Wear Mechanisms and Debris in Hip Implants.

PubMed

Schappo, Henrique; Gindri, Izabelle M; Cubillos, Patrícia O; Maru, Marcia M; Salmoria, Gean V; Roesler, Carlos R M

2018-01-01

The use of scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS) was investigated to understand the wear mechanisms from a metal-on-polyethylene bearing couple. Morphological features of femoral head acetabular liner, and isolated particles resulting from hip wear testing were evaluated. EDS was proposed to investigate the polymeric nature of the particles isolated from the wear testing. In this work, 28-mm conventional ultra-high-molecular-weight polyethylene acetabular liners paired with metallic heads were tested in a hip wear simulator over 2 million cycles. SEM-EDS was employed to investigate wear mechanisms on hip implant components and associated wear debris. SEM showed worn surfaces for both hip components, and a significant volume of ultra-high-molecular-weight polyethylene wear particles resulting from hip wear testing. Particles were classified into 3 groups, which were then correlated to wear mechanisms. Group I had particles with smooth surfaces, group II consisted of particles with rough surfaces, and group III comprised aggregate-like particles. Group I EDS revealed that particles from groups I and II had a high C/O ratio raising a concern about the particle source. On the other hand, particles from group III had a low C/O ratio, supporting the hypothesis that they resulted from the wear of acetabular liner. Most of particles identified in group III were in the biologically active size range (0.3 to 20 μm). The use of optical and electron microscopy enabled the morphological characterization of worn surfaces and wear debris, while EDS was essential to elucidate the chemical composition of isolated debris. Copyright © 2017 Elsevier Inc. All rights reserved.

Terrestrially derived glomalin-related soil protein quality as a potential ecological indicator in a peri-urban watershed.

PubMed

Sui, Xueyan; Wu, Zhipeng; Lin, Chen; Zhou, Shenglu

2017-07-01

Glomalin, which sequesters substantial amounts of carbon, plays a critical role in sustaining terrestrial biome functions and contributes to the fate of many pollutants from terrestrial to aquatic ecosystems. Despite having focused on the amount of glomalin produced, very few attempts have been made to understand how landscapes and environmental conditions influence glomalin composition and characteristics. This study focused on glomalin-related soil protein (GRSP) exported as storm runoff including eroded sediment and water that was collected before flowing to surface waters in a peri-urban watershed. GRSP characteristics were assessed by Bradford protein analysis, fluorescence spectroscopy combined with parallel factor analysis (PARAFAC), and the determination of aromaticity based on the specific ultraviolet absorption value (280 nm) and molecular weight. General linear models (GLMs) was established by integrating microbial activity, land cover, water temperature, precipitation, and other solution chemical properties to explain the variations in GRSP characteristics. Results showed that a higher GRSP concentration in agricultural reference sites was produced in the form of specific materials with low molecular weight and aromaticity, as well as high percentage of C1 and C5 components which indicate microbial-processed sources, relative to urbanized and forested sites. Compared with forested land, urbanized land clearly produced runoff GRSP with low molecular weight and aromaticity, as well as more degradation of humic-like materials (C3 component). The highest GLM explaining 89% of the variables, including significant variables (p < 0.05) such as microbial activity, water temperature, and water conductivity, was observed for GRSP characteristics. Therefore, changes in eroded soil GRSP quality can serve as an indicator for improving watershed management and thus protecting aquatic ecosystems.

Positive and negative impacts of specialty malts on beer foam: a comparison of various cereal products for their foaming properties.

PubMed

Combe, Alexander L; Ang, Justin K; Bamforth, Charles W

2013-07-01

The foam stability of beer is dependent on the presence of foam-stabilizing polypeptides derived from the cereals from which it is made. It has long been argued that there is a tendency to boost the foam-stabilizing capabilities of these polypeptides at the heating stages involved in the production of the grist materials. The present study started with the intent to confirm whether these changes occurred and to assess the extent to which different cereal products differed in their foam-stabilizing tendencies. Cereal products differ enormously in their foam-stabilizing capabilities. Heavily roasted grains, notably black malt and roast barley, do have superior foaming properties. However, certain specialty malts, notably crystal malts, display inferior foam performance. The observed foaming pattern is a balance between their content of foam-positive and foam-negative components. Products such as pale malt do contain foam-negative materials but have a net balance in favour of foam-stabilizing entities. By contrast, wheat malt and especially black malt have a heavy preponderance of foam-positive components. Crystal malt displays the converse behaviour: it contains low-molecular-weight foam-negative species. Several of the cereal products appear to contain higher-molecular-weight foam inhibitors, but it appears that they are merely species that are of inherently inferior foam-stabilizing capability to the foaming polypeptides from egg white that were employed to probe the system. The foam-damaging species derived from crystal malt carried through to beers brewed from them. Intense heating in the production of cereal products does lead to enhanced foam performance in extracts of those products. However, not all speciality malts display superior foam performance, through their development of foam-negative species of lower molecular weight. © 2013 Society of Chemical Industry.

The Adjuvant Effects of High-Molecule-Weight Polysaccharides Purified from Antrodia cinnamomea on Dendritic Cell Function and DNA Vaccines

PubMed Central

Lin, Chi-Chen; Pan, I-Hong; Li, Yi-Rong; Pan, Yi-Gen; Lin, Ming-Kuem; Lu, Yi-Huang; Wu, Hsin-Chieh; Chu, Ching-Liang

2015-01-01

The biological activity of the edible basidiomycete Antrodia cinnamomea (AC) has been studied extensively. Many effects, such as anti-cancer, anti-inflammatory, and antioxidant activities, have been reported from either crude extracts or compounds isolated from AC. However, research addressing the function of AC in enhancing immunity is rare. The aim of the present study is to investigate the active components and the mechanism involved in the immunostimulatory effect of AC. We found that polysaccharides (PS) in the water extract of AC played a major role in dendritic cell (DC) activation, which is a critical leukocyte in initiating immune responses. We further size purified and identified that the high-molecular weight PS fraction (greater than 100 kDa) exhibited the activating effect. The AC high-molecular weight PSs (AC hmwPSs) promoted pro-inflammatory cytokine production by DCs and the maturation of DCs. In addition, DC-induced antigen-specific T cell activation and Th1 differentiation were increased by AC hmwPSs. In studying the molecular mechanism, we confirmed the activation of the MAPK and NF-κB pathways in DCs after AC hmwPSs treatment. Furthermore, we demonstrated that TLR2 and TLR4 are required for the stimulatory activity of AC hmwPSs on DCs. In a mouse tumor model, we demonstrated that AC hmwPSs enhanced the anti-tumor efficacy of the HER-2/neu DNA vaccine by facilitating specific Th1 responses. Thus, we conclude that hmwPSs are the major components of AC that stimulate DCs via the TLR2/TLR4 and NF-κB/MAPK signaling pathways. The AC hmwPSs have potential to be applied as adjuvants. PMID:25723174

The structure of a β-(1→3)-d-glucan from yeast cell walls

PubMed Central

Manners, David J.; Masson, Alan J.; Patterson, James C.

1973-01-01

Yeast glucan as normally prepared by various treatments of yeast (Saccharomyces cerevisiae) cell walls to remove mannan and glycogen is still heterogeneous. The major component (about 85%) is a branched β-(1→3)-glucan of high molecular weight (about 240000) containing 3% of β-(1→6)-glucosidic interchain linkages. The minor component is a branched β-(1→6)-glucan. A comparison of our results with those of other workers suggests that different glucan preparations may differ in the degree of heterogeneity and that the major β-(1→3)-glucan component may vary considerably in degree of branching. PMID:4359920

AXOPLASMIC PROTEINS OF THE SQUID GIANT NERVE FIBER WITH PARTICULAR REFERENCE TO THE FIBROUS PROTEIN

PubMed Central

Maxfield, Myles

1953-01-01

1. Axoplasm of squid giant nerve fibers is examined with the ultracentrifuge and electrophoresis apparatus and several distinct components demonstrated. 2. One of these components, a protein called axon filaments, is isolated by fractional extraction followed by differential ultracentrifugation and redissolving in glycine solution. Axon filaments are monodisperse by ultracentrifugation. Their physical chemical properties have been studied. 3. The existence of a reversible transformation of axon filaments into a particle of lower molecular weight and lower asymmetry has been demonstrated. PMID:13109156

Synergistic effect of high and low molecular weight molecules in the foamability and foam stability of sparkling wines.

PubMed

Coelho, Elisabete; Reis, Ana; Domingues, M Rosário M; Rocha, Sílvia M; Coimbra, Manuel A

2011-04-13

The foam of sparkling wines is a key parameter of their quality. However, the compounds that are directly involved in foam formation and stabilization are not yet completely established. In this work, seven sparkling wines were produced in Bairrada appellation (Portugal) under different conditions and their foaming properties evaluated using a Mosalux-based device. Fractionation of the sparkling wines into four independent fractions, (1) high molecular weight material, with molecular weight higher than 12 kDa (HMW), (2) hydrophilic material with molecular weigh between 1 and 12 kDa (AqIMW), (3) hydrophobic material with molecular weigh between 1 and 12 kDa (MeIMW), and (4) hydrophobic material with a molecular weight lower than 1 kDa (MeLMW), allowed the observation that the wines presenting the lower foam stability were those that presented lower amounts of the MeLMW fraction. The fraction that presented the best foam stability was HMW. When HMW is combined with MeLMW fraction, the foam stability largely increased. This increase was even larger, approaching the foam stability of the sparkling wine, when HMW was combined with the less hydrophobic subfraction of MeLMW (fraction 3). Electrospray tandem mass spectrometry (ESI-MS/MS) of fraction 3 allowed the assignment of polyethylene glycol oligomers (n = 5-11) and diethylene glycol 8-hydroxytridecanoate glyceryl acetate. To observe if these molecules occur in sparkling wine foam, the MeLMW was recovered directly from the sparkling wine foam and was also analyzed by ESI-MS/MS. The presence of monoacylglycerols of palmitic and stearic acids, as well as four glycerylethylene glycol fatty acid derivatives, was observed. These surface active compounds are preferentially partitioned by the sparkling wine foam rather than the liquid phase, allowing the inference of their role as key components in the promotion and stabilization of sparkling wine foam.

Dissolved organic matter in anoxic pore waters from Mangrove Lake, Bermuda

USGS Publications Warehouse

Orem, W.H.; Hatcher, P.G.; Spiker, E. C.; Szeverenyi, N.M.; Maciel, G.E.

1986-01-01

Dissolved organic matter and dissolved inorganic chemical species in anoxic pore water from Mangrove Lake, Bermuda sediments were studied to evaluate the role of pore water in the early diagenesis of organic matter. Dissolved sulphate, titration alkalinity, phosphate, and ammonia concentration versus depth profiles were typical of many nearshore clastic sediments and indicated sulphate reduction in the upper 100 cm of sediment. The dissolved organic matter in the pore water was made up predominantly of large molecules, was concentrated from large quantities of pore water by using ultrafiltration and was extensively tudied by using elemental and stable carbon isotope analysis and high-resolution, solid state 13C nuclear magnetic resonance and infrared spectroscopy. The results indicate that this material has a predominantly polysaccharide-like structure and in addition contains a large amount of oxygen-containing functional groups (e.g., carboxyl groups). The 13C nulcear magnetic resonance spectra of the high-molecular-weight dissolved organic matter resemble those of the organic matter in the surface sediments of Mangrove Lake. We propose that this high-molecular-weight organic matter in pore waters represents the partially degraded, labile organic components of the sedimentary organic matter and that pore waters serve as a conduit for removal of these labile organic components from the sediments. The more refractory components are, thus, selectively preserved in the sediments as humic substances (primarily humin). ?? 1986.

Effect of molecular weight, temperature, and additives on the moisture sorption properties of polyethylene glycol.

PubMed

Baird, Jared A; Olayo-Valles, Roberto; Rinaldi, Carlos; Taylor, Lynne S

2010-01-01

Polyethylene glycol (PEG) is a hygroscopic polymer that undergoes the phenomenon of deliquescence once a critical relative humidity (RH(0)) is reached. The purpose of this study was to test the hypothesis that the deliquescence behavior of PEG will be affected by the polymer molecular weight, temperature, and the presence of additives. The deliquescence relative humidity for single component (RH(0)) and binary mixtures (RH(0,mix)) were measured using an automated gravimetric moisture analyzer at 25 and 40 degrees C. Changes in PEG crystallinity after exposure to moisture were qualitatively assessed using powder X-ray diffraction (PXRD). Optical microscopy was used to visually observe the deliquescence phenomenon. For single component systems, decreasing PEG MW and elevating the temperature resulted in a decrease in the observed RH(0). Physical mixtures of acetaminophen and anhydrous citric acid with both PEG 3350 and PEG 100,000 exhibited deliquescence (RH(0,mix)) at a relative humidity below that of either individual component. Qualitative changes in crystallinity were observed from the X-ray diffractograms for each PEG MW grade at high relative humidities, indicating that phase transformation (deliquescence) of the samples had occurred. In conclusion, it was found that the deliquescence behavior of PEG was affected by the polymer MW, temperature, and the presence of additives. This phenomenon may have important implications for the stability of PEG containing formulations.

Molecular Weight Effects on the Viscoelastic Response of a Polyimide

NASA Technical Reports Server (NTRS)

Nicholson, Lee M.; Whitley, Karen S.; Gates, Thomas S.

2000-01-01

The effect of molecular weight on the viscoelastic performance of an advanced polymer (LaRC -SI) was investigated through the use of creep compliance tests. Testing consisted of short-term isothermal creep and recovery with the creep segments performed under constant load. The tests were conducted at three temperatures below the glass transition temperature of each material with different molecular weight. Through the use of time-aging-time superposition procedures, the material constants, material master curves and aging-related parameters were evaluated at each temperature for a given molecular weight. The time-temperature superposition technique helped to describe the effect of temperature on the timescale of the viscoelastic response of each molecular weight. It was shown that the low molecular weight materials have increased creep compliance and creep compliance rate, and are more sensitive to temperature than the high molecular weight materials. Furthermore, a critical molecular weight transition was observed to occur at a weight-average molecular weight of approximately 25000 g/mol below which, the temperature sensitivity of the time-temperature superposition shift factor increases rapidly.

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

Siegel, A.

Previous work had demonstrated the presence of a unique low-molecular-weight RNA component (LMC) in extracts of tobacco mosaic virus (TMV) infected tissue. Enough of this component has been isolated during the past year to ascertain that it has a molecular weight of 250,000 daltons and that it acts as an in vitro messenger for the synthesis of TMV capsid protein. Thus, we conclude that at least one monocistronic messenger RNA for a virion coded product is generated during TMV infection. Strains of TMV were classified according to nucleotide sequence homology of their RNAs. The strains fall into groups by themore » test employed. No differences were observed between strains within a group, whereas no homology was detected between groups. Using this information, it was possible, in part, to relate differences in capsid protein amino acid sequences to the degree of nomology of their nucleotide coding sequences. A study was initiated into the Pot Y virus group infection mechanism. In contrast to TMV infection, it was determined that for both tobacco etch and potato virus Y that: viral RNA synthesis is inhibited by actinomycin B and synthesis by virus-related proteins is inhibited by chloramphenicol.« less

Competing Stereocomplexation and Homocrystallization of Poly(l-lactic acid)/Poly(d-lactic acid) Racemic Mixture: Effects of Miscible Blending with Other Polymers.

PubMed

Bao, Jianna; Xue, Xiaojia; Li, Kai; Chang, Xiaohua; Xie, Qing; Yu, Chengtao; Pan, Pengju

2017-07-20

Promoting the stereocomplexation ability of high-molecular-weight poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) is an efficient way to improve the thermal resistance of the resulting materials. Herein, we studied the competing crystallization kinetics, polymorphic crystalline structure, and lamellae structure of the PLLA/PDLA component in its miscible blends with poly(vinyl acetate) (PVAc) and proposed a method to improve the stereocomplexation ability of PLLA and PDLA through miscible blending with the other polymer. Crystallization of the PLLA/PDLA component is suppressed after the addition of PVAc, due to the dilution effect. The stereocomplexation ability of PLLA and PDLA is enhanced by blending with PVAc; this becomes more obvious at a high PVAc content (≥50 wt %) but less significant with the further increase of PLLA, PDLA molecular weights. Almost exclusive formation of SCs is achieved for PLLA and PDLA after blending with a large proportion of PVAc (e.g., 75 wt %). Incorporation of PVAc also facilitates the HC-to-SC structural reorganization upon heating. The increased chain mobility, decreased equilibrium melting point, and enhanced intermolecular interactions may account for the preferential stereocomplexation in PLLA/PDLA/PVAc blends.

Characterization of pitch prepared from pyrolysis fuel oil via electron beam irradiation

NASA Astrophysics Data System (ADS)

Kim, Hong Gun; Park, Mira; Kim, Hak-Yong; Kwac, Lee Ku; Shin, Hye Kyoung

2017-06-01

Pitch samples were obtained from pyrolysis fuel oil by thermal treatment for 2 h at 300 °C after electron beam irradiation (EBI) treatment and by thermal treatment alone for different temperature of 250 °C, 300 °C, and 350 °C. EBI treatment was found to be an effective treatment for preparing pitch compare to the pitch obtained without EBI treatment. These results were confirmed by Fourier transform infrared spectroscopy (FT-IR) and Carbon-13 nuclear magnetic resonance (13C NMR) analyses, which showed the increase in the intensities of peaks corresponding to aromatic compounds. In the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) spectra, the amount of components with medium molecular weights in the pitch was found to increase with the temperature; likewise, in the case of the pitch obtained via EBI treatment, we found that the amount of components with higher molecular weight over 1000 (m/v) similarly increased. Further, the thermal stability and carbon yield at 850 °C of the pitch obtained by EBI were greater than those of samples subjected to thermal treatment at 250 and 300 °C.

Fractionation of Organosolv Lignin Using Acetone:Water and Properties of the Obtained Fractions

DOE PAGES

Sadeghifar, Hasan; Wells, Tyrone; Le, Rosemary Khuu; ...

2016-11-07

In this study, lignin fractions with different molecular weight were prepared using a simple and almost green method from switchgrass and pine organosolv lignin. Different proportions of acetone in water, ranging from 30 to 60%, were used for lignin fractionation. A higher concentration of acetone dissolved higher molecular weight fractions of the lignin. Fractionated organosolv lignin showed different molecular weight and functional groups. Higher molecular weight fractions exhibited more aliphatic and less phenolic OH than lower molecular weight fractions. Lower molecular weight fractions lead to more homogeneous structure compared to samples with a higher molecular weight. In conclusion, all fractionsmore » showed strong antioxidant activity.« less

Application of ion-induced nucleation mass spectrometry in the analysis of trace gases evolved from a polyimide film during the thermal curing stages

NASA Technical Reports Server (NTRS)

Smith, A. C.

1982-01-01

Trace gases evolved from a polyimide film during its thermal curing stages have been studied using ion-induced nucleation mass spectrometry. The technique involved exposing the test gas sample to a low energy beta source and recording the masses of the ion-induced molecular clusters formed in the reaction chamber. On the basis of the experimentally observed molecular cluster spectra, it has been concluded that the dominant trace component had a molecular weight of 87 atomic mass units. This component has been identified as a molecule of dimethylacetamide (DMAC) which had been used as a solvent in the preparation of the test polyimide specimen. This identification has been further confirmed by comparing the spectra of the test gas sample and the DMAC calibration sample obtained with a conventional mass spectrometer. The advantages of the ion-induced nucleation mass spectrometer versus the conventional mass spectrometer are discussed.

Degradation mechanisms of bioresorbable polyesters. Part 2. Effects of initial molecular weight and residual monomer.

PubMed

Gleadall, Andrew; Pan, Jingzhe; Kruft, Marc-Anton; Kellomäki, Minna

2014-05-01

This paper presents an understanding of how initial molecular weight and initial monomer fraction affect the degradation of bioresorbable polymers in terms of the underlying hydrolysis mechanisms. A mathematical model was used to analyse the effects of initial molecular weight for various hydrolysis mechanisms including noncatalytic random scission, autocatalytic random scission, noncatalytic end scission or autocatalytic end scission. Different behaviours were identified to relate initial molecular weight to the molecular weight half-life and to the time until the onset of mass loss. The behaviours were validated by fitting the model to experimental data for molecular weight reduction and mass loss of samples with different initial molecular weights. Several publications that consider initial molecular weight were reviewed. The effect of residual monomer on degradation was also analysed, and shown to accelerate the reduction of molecular weight and mass loss. An inverse square root law relationship was found between molecular weight half-life and initial monomer fraction for autocatalytic hydrolysis. The relationship was tested by fitting the model to experimental data with various residual monomer contents. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Evaluation of the separation performance of polyvinylpyrrolidone as a virtual stationary phase for chromatographic NMR.

PubMed

Huang, Shaohua; Wu, Rui; Bai, Zhengwu; Yang, Ying; Li, Suying; Dou, Xiaowei

2014-09-01

Polyvinylpyrrolidone (PVP) was used as a virtual stationary phase to separate p-xylene, benzyl alcohol, and p-methylphenol by the chromatographic NMR technique. The effects of concentration and weight-average molecular weight (Mw) of PVP, solvent viscosity, solvent polarity, and sample temperature on the resolution of these components were investigated. It was found that both higher PVP concentration and higher PVP Mw caused the increase of diffusion resolution for the three components. Moreover, the diffusion resolution did not change at viscosity-higher solvents. Moreover, the three components showed different resolution at different solvents. As temperature increased, the diffusion resolution between p-xylene and benzyl alcohol gradually increased, and the one between p-xylene and p-methylphenol slightly increased from 278 to 298 K and then decreased above 298 K. It was also found that the polarity of the analytes played an important role for the separation by affecting the diffusion coefficient. Copyright © 2014 John Wiley & Sons, Ltd.

Fine-mapping of qGW4.05, a major QTL for kernel weight and size in maize.

PubMed

Chen, Lin; Li, Yong-xiang; Li, Chunhui; Wu, Xun; Qin, Weiwei; Li, Xin; Jiao, Fuchao; Zhang, Xiaojing; Zhang, Dengfeng; Shi, Yunsu; Song, Yanchun; Li, Yu; Wang, Tianyu

2016-04-12

Kernel weight and size are important components of grain yield in cereals. Although some information is available concerning the map positions of quantitative trait loci (QTL) for kernel weight and size in maize, little is known about the molecular mechanisms of these QTLs. qGW4.05 is a major QTL that is associated with kernel weight and size in maize. We combined linkage analysis and association mapping to fine-map and identify candidate gene(s) at qGW4.05. QTL qGW4.05 was fine-mapped to a 279.6-kb interval in a segregating population derived from a cross of Huangzaosi with LV28. By combining the results of regional association mapping and linkage analysis, we identified GRMZM2G039934 as a candidate gene responsible for qGW4.05. Candidate gene-based association mapping was conducted using a panel of 184 inbred lines with variable kernel weights and kernel sizes. Six polymorphic sites in the gene GRMZM2G039934 were significantly associated with kernel weight and kernel size. The results of linkage analysis and association mapping revealed that GRMZM2G039934 is the most likely candidate gene for qGW4.05. These results will improve our understanding of the genetic architecture and molecular mechanisms underlying kernel development in maize.

A physico-chemical assessment of the thermal stability of pneumococcal conjugate vaccine components

PubMed Central

Gao, Fang; Lockyer, Kay; Burkin, Karena; Crane, Dennis T; Bolgiano, Barbara

2014-01-01

Physico-chemical analysis of pneumococcal polysaccharide (PS)-protein conjugate vaccine components used for two commercially licensed vaccines was performed to compare the serotype- and carrier protein-specific stabilities of these vaccines. Nineteen different monovalent pneumococcal conjugates from commercial vaccines utilizing CRM197, diphtheria toxoid (DT), Protein D (PD) or tetanus toxoid (TT) as carrier proteins were incubated at temperatures up to 56°C for up to eight weeks or were subjected to freeze-thawing (F/T). Structural stability was evaluated by monitoring their size, integrity and carrier protein conformation. The molecular size of the vaccine components was well maintained for Protein D, TT and DT conjugates at -20°C, 4°C and F/T, and for CRM197 conjugates at 4°C and F/T. It was observed that four of the eight serotypes of Protein D conjugates tended to form high molecular weight complexes at 37°C or above. The other conjugated carrier proteins also appeared to form oligomers or ‘aggregates’ at elevated temperatures, but rarely when frozen and thawed. There was evidence of degradation in some of the conjugates as evidenced by the formation of lower molecular weight materials which correlated with measured free saccharide. In conclusion, pneumococcal-Protein D/TT/DT and most CRM197 bulk conjugate vaccines were stable when stored at 2–8°C, the recommended temperature. In common between the conjugates produced by the two manufacturers, serotypes 1, 5, and 19F were relatively less stable and 6B was the most stable, with types 7F and 23F also showing good stability. PMID:25483488

Formation of high-molecular-weight compounds via the heterogeneous reactions of gaseous C8-C10 n-aldehydes in the presence of atmospheric aerosol components

NASA Astrophysics Data System (ADS)

Han, Yuemei; Kawamura, Kimitaka; Chen, Qingcai; Mochida, Michihiro

2016-02-01

A laboratory study on the heterogeneous reactions of straight-chain aldehydes was performed by exposing n-octanal, nonanal, and decanal vapors to ambient aerosol particles. The aerosol and blank filters were extracted using methanol. The extracts were nebulized and the resulting compositions were examined using a high-resolution time-of-flight aerosol mass spectrometer. The mass spectral analysis showed that the exposures of the aldehydes to aerosol samples increased the peak intensities in the high mass range. The peaks in the mass spectra of the aerosol samples after exposure to different aldehydes were characterized by a homologous series of peak shifts due to the addition of multiple CH2 units. This result is explained by the formation of high-molecular-weight (HMW) compounds that contain single or multiple aldehyde moieties. The HMW fragment peaks for the blank filters exposed to n-aldehydes were relatively weak, indicating an important contribution from the ambient aerosol components to the formation of the HMW compounds. Among the factors affecting the overall interaction of aldehydes with atmospheric aerosol components, gas phase diffusion possibly limited the reactions under the studied conditions; therefore, their occurrence to a similar degree in the atmosphere is not ruled out, at least for the reactions involving n-nonanal and decanal. The major formation pathways for the observed HMW products may be the self-reactions of n-aldehydes mediated by atmospheric aerosol components and the reactions of n-aldehydes with organic aerosol components. The observed formation of HMW compounds encourages further investigations into their effects on the aerosol properties as well as the organic aerosol mass in the atmosphere.

Ocean metabolism and dissolved organic matter: How do small dissolved molecules persist in the ocean?

NASA Astrophysics Data System (ADS)

Benner, Ronald

2010-05-01

The ocean reservoir of dissolved organic matter (DOM) is among the largest global reservoirs (~700 Pg C) of reactive organic carbon. Marine primary production (~50 Pg C/yr) by photosynthetic microalgae and cyanobacteria is the major source of organic matter to the ocean and the principal substrate supporting marine food webs. The direct release of DOM from phytoplankton and other organisms as well as a variety of other processes, such as predation and viral lysis, contribute to the ocean DOM reservoir. Continental runoff and atmospheric deposition are relatively minor sources of DOM to the ocean, but some components of this material appear to be resistant to decomposition and to have a long residence time in the ocean. Concentrations of DOM are highest in surface waters and decrease with depth, a pattern that reflects the sources and diagenesis of DOM in the upper ocean. Most (70-80%) marine DOM exists as small molecules of low molecular weight (<1 kDalton). Surprisingly, high-molecular-weight (>1 kDalton) DOM is relatively enriched in major biochemicals, such as combined neutral sugars and amino acids, and is more bioavailable than low-molecular-weight DOM. The observed relationships among the size, composition, and reactivity of DOM have led to the size-reactivity continuum model, which postulates that diagenetic processes lead to the production of smaller molecules that are structurally altered and resistant to microbial degradation. The radiocarbon content of these small dissolved molecules also indicates these are the most highly aged components of DOM. Chemical signatures of bacteria are abundant in DOM and increase during diagenesis, indicating bacteria are an important source of slowly cycling biochemicals. Recent analyses of DOM isolates by ultrahigh-resolution mass spectrometry have revealed an incredibly diverse mixture of molecules. Carboxyl-rich alicyclic molecules are abundant in DOM, and they appear to be derived from diagenetically-altered terpenoids, such as sterols and hopanoids. Thermally-altered molecules, including black carbon, also appear to be important components of DOM, but their origins are unclear. We are rapidly acquiring novel information about the composition and molecular identity of DOM, and novel insights about the origins, transformations and fates this vast reservoir of DOM are emerging. This presentation will review and synthesize this information for comparison with non-living organic matter in other systems.

Properties of the polysaccharide and mucopeptide components of the cell wall of Lactobacillus casei

PubMed Central

Hall, Elizabeth A.; Knox, K. W.

1965-01-01

1. The polysaccharide and mucopeptide components of the cell wall of Lactobacillus casei have been separated by mild conditions of acid hydrolysis. 2. Removal of the polysaccharide renders the mucopeptide susceptible to lysozyme. 3. The mucopeptide and polysaccharide components have been analysed and the results compared with those obtained previously. 4. The polysaccharides responsible for group specificity have a terminal reducing N-acetylgalactosamine residue substituted on C(3) by the adjacent sugar; estimation of this component gave an indication of the molecular weight of the polysaccharides. 5. Evidence has been obtained for the presence of rhamnosyl-(1→3)-N-acetylgalactosamine among the products of acid hydrolysis of the group B polysaccharide. ImagesFig. 2. PMID:5837778

Fluorescence fingerprints and Cu2+-complexing ability of individual molecular size fractions in soil- and waste-borne DOM.

PubMed

Knoth de Zarruk, K; Scholer, G; Dudal, Y

2007-09-01

Land spreading of organic materials introduces large amounts of dissolved organic matter (DOM) into the soil. DOM has the ability to form stable complexes with heavy metals and can facilitate their transport towards the groundwater. The effects on soil processes are difficult to assess, because different DOM components might react differently towards metal ions. The objective of this study was to investigate the fluorescence signature and the Cu2+-binding capacity of individual molecular size fractions of DOM from various sources. DOM extracted from leaf compost, chicken manure, sugar cane vinasse and a fulvic hypercalcaric cambisol was fractionated by the means of dialysis into four molecular size classes: MW<500, 50012000-14000 Da. Vinasse and leaf compost contained around 80% and 70%, respectively, of the total organic carbon in the fractions with low molecular weight (MW<3500 Da); in chicken manure and soil these fractions accounted for 40% and 50% only. Fluorescence was highest in the fraction MW>12000 Da for leaf compost, chicken manure and soil. The opposite result was obtained for vinasse, where the fractions with low molecular weight showed highest fluorescence intensities, distinguishing it from all other samples. Vinasse showed the greatest ability to bind Cu2+ with a resulting complex concentration of 6.31mgl(-1) while in contact with an excess of Cu2+. Leaf compost, soil and chicken manure followed with 2.69, 1.12, and 0.85mgl(-1), respectively. Within vinasse, the fraction MW<500 Da was able to form the most DOM-Cu complexes, indicating the importance of low molecular weight fractions in metal binding.

Ultrahigh molecular weight aromatic siloxane polymers

NASA Technical Reports Server (NTRS)

Ludwick, L. M.

1982-01-01

The condensation of a diol with a silane in toluene yields a silphenylene-siloxane polymer. The reaction of stiochiometric amounts of the diol and silane produced products with molecular weights in the range 2.0 - 6.0 x 10 to the 5th power. The molecular weight of the product was greatly increased by a multistep technique. The methodology for synthesis of high molecular weight polymers using a two step procedure was refined. Polymers with weight average molecular weights in excess of 1.0 x 10 to the 6th power produced by this method. Two more reactive silanes, bis(pyrrolidinyl)dimethylsilane and bis(gamma butyrolactam)dimethylsilane, are compared with the dimethyleminodimethylsilane in ability to advance the molecular weight of the prepolymer. The polymers produced are characterized by intrinsic viscosity in tetrahydrofuran. Weight and number average molecular weights and polydispersity are determined by gel permeation chromatography.

Isolation and partial purification of anticoagulant fractions from the venom of the Iranian snake Echis carinatus.

PubMed

Babaie, Mahdi; Zolfagharian, Hossein; Salmanizadeh, Hossein; Mirakabadi, Abbas Zare; Alizadeh, Hafezeh

2013-01-01

Many snake venoms comprise different factors, which can either promote or inhibit the blood coagulation pathway. Coagulation disorders and hemorrhage belong to the most prominent features of bites of the many vipers. A number of these factors interact with components of the human blood coagulation. This study is focused on the effect of Echis carinatus snake venom on blood coagulation pathway. Anticoagulant factors were purified from the Iranian Echis carinatus venom by two steps: gel filtration (Sephadex G-75) and ion-exchange (DEAE-Sephadex) chromatography, in order to study the anticoagulant effect of crude venom and their fractions. The prothrombin time was estimated on human plasma for each fraction. Our results showed that protrombin time value was increase from 13.4 s to 170 s for F2C and to 280 s for F2D. Our study showed that these fractions of the venom delay the prothrombine time and thus can be considered as anticoagulant factors. They were shown to exhibit proteolytic activity. The molecular weights of these anticoagulants (F2C, F2D) were estimated by SDS/PAGE electrophoresis. F2C comprises two protein bands with molecular weights of 50 and 79 kDa and F2D a single band with a molecular weight of 42 kDa.

Low molecular weight hyaluronic acid effects on murine macrophage nitric oxide production.

PubMed

Lyle, Daniel B; Breger, Joyce C; Baeva, Larissa F; Shallcross, Jonathan C; Durfor, Charles N; Wang, Nam Sun; Langone, John J

2010-09-01

Hyaluronic acid (HA) is increasingly used for a number of medical device applications. Since the chemical structure of HA is identical no matter its bacterial or animal origin, it should be the ideal biomaterial. However, short term transient inflammatory reactions are common, while rare long-term adverse events may correlate with subclinical chronic inflammation. Concern has been raised that low molecular weight components or degradation fragments from implanted HA may directly stimulate inflammatory reactions. This study examined a panel of HA molecular weights from the unitary disaccharide up to 1.7 x 10(6) Dalton lengths, in which endotoxin was assayed at a very low level (less than 0.03 EU/mg). The murine cell line RAW 264.7, rat splenocytes, and rat adherent differentiated primary macrophages were assayed for nitric oxide production under a variety of inflammatory conditions plus or minus HA. Under the highest inflammatory states, nitric oxide production was mildly suppressed by HMW-HA while slightly augmented by LMW-HA at mg/mL concentrations. However, at micromolar concentrations fragments below 5000 Daltons, thought to have drug-like qualities, were without effect. These data support the hypothesis that if endotoxin is reduced to an extremely low level, LMW-HA may not directly provoke normal tissue macrophage-mediated inflammatory reactions. (c) 2010 Wiley Periodicals, Inc.

Comparison of microdialysis sampling perfusion fluid components on the foreign body reaction in rat subcutaneous tissue.

PubMed

Keeler, Geoffrey D; Durdik, Jeannine M; Stenken, Julie A

2014-06-16

Microdialysis sampling is a commonly used technique for collecting solutes from the extracellular space of tissues in laboratory animals and humans. Large molecular weight solutes can be collected using high molecular weight cutoff (MWCO) membranes (100kDa or greater). High MWCO membranes require addition of high molecular weight dextrans or albumin to the perfusion fluid to prevent fluid loss via ultrafiltration. While these perfusion fluid additives are commonly used during microdialysis sampling, the tissue response to the loss of these compounds across the membrane is poorly understood. Tissue reactions to implanted microdialysis sampling probes containing different microdialysis perfusion fluids were compared over a 7-day time period in rats. The base perfusion fluid was Ringer's solution supplemented with either bovine serum albumin (BSA), rat serum albumin (RSA), Dextran-70, or Dextran-500. A significant inflammatory response to Dextran-70 was observed. No differences in the tissue response between BSA and RSA were observed. Among these agents, the BSA, RSA, and Dextran-500 produced a significantly reduced inflammatory response compared to the Dextran-70. This work demonstrates that use of Dextran-70 in microdialysis sampling perfusion fluids should be eliminated and replaced with Dextran-500 or other alternatives. Copyright © 2013 Elsevier B.V. All rights reserved.

Emulsifying Activity and Stability of a Non-Toxic Bioemulsifier Synthesized by Microbacterium sp. MC3B-10

PubMed Central

Camacho-Chab, Juan Carlos; Guézennec, Jean; Chan-Bacab, Manuel Jesús; Ríos-Leal, Elvira; Sinquin, Corinne; Muñiz-Salazar, Raquel; De la Rosa-García, Susana del C.; Reyes-Estebanez, Manuela; Ortega-Morales, Benjamín Otto

2013-01-01

A previously reported bacterial bioemulsifier, here termed microbactan, was further analyzed to characterize its lipid component, molecular weight, ionic character and toxicity, along with its bioemulsifying potential for hydrophobic substrates at a range of temperatures, salinities and pH values. Analyses showed that microbactan is a high molecular weight (700 kDa), non-ionic molecule. Gas chromatography of the lipid fraction revealed the presence of palmitic, stearic, and oleic acids; thus microbactan may be considered a glycolipoprotein. Microbactan emulsified aromatic hydrocarbons and oils to various extents; the highest emulsification index was recorded against motor oil (96%). The stability of the microbactan-motor oil emulsion model reached its highest level (94%) at 50 °C, pH 10 and 3.5% NaCl content. It was not toxic to Artemia salina nauplii. Microbactan is, therefore, a non-toxic and non-ionic bioemulsifier of high molecular weight with affinity for a range of oily substrates. Comparative phylogenetic assessment of the 16S rDNA gene of Microbacterium sp. MC3B-10 with genes derived from other marine Microbacterium species suggested that this genus is well represented in coastal zones. The chemical nature and stability of the bioemulsifier suggest its potential application in bioremediation of marine environments and in cosmetics. PMID:24065097

Characterization and analysis of the molecular weight of lignin for biorefining studies

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

Tolbert, Allison; Akinosho, Hannah; Khunsupat, Ratayakorn

2014-06-04

The molecular weight of lignin is a fundamental property that infl uences the recalcitrance of biomass and the valorization of lignin. The determination of the molecular weight of lignin in native biomass is dependent on the bioresources used and the isolation and purifi cation procedures employed. The three most commonly employed isolation methods are milled wood lignin (MWL), cellulolytic enzyme lignin (CEL), and enzymatic mild acidolysis lignin (EMAL). Common characterization techniques for determining the molecular weight of lignin will be addressed, with an emphasis on gel permeation chromatography (GPC). This review also examines the mechanisms behind several biological, physical, andmore » chemical pre-treatments and their impact on the molecular weight of lignin. The number average molecular weight (Mn), weight average molecular weight (Mw) and polydispersity index (D) all vary in magnitude depending on the biomass source, pre-treatment conditions, and isolation method. Additionally, there is a growing body of literature that supports changes in the molecular weight of lignin in response to genetic modifi cations in the lignin biosynthetic pathways. This review summarizes different procedures for obtaining the molecular weight of lignin that have been used in recent years and highlight future opportunities for applications of lignin.« less

Optical and size characterization of dissolved organic matter from the lower Yukon River

NASA Astrophysics Data System (ADS)

Guo, L.; Lin, H.

2017-12-01

The Arctic rivers have experienced significant climate and environmental changes over the last several decades and their export fluxes and environmental fate of dissolved organic matter (DOM) have received considerable attention. Monthly or bimonthly water samples were collected from the Yukon River, one of the Arctic rivers, between July 2004 and September 2005 for size fractionation to isolate low-molecular-weight (LMW, <1 kDa) and high-molecular-weight (HMW, >1 kDa) DOM. The freeze-dried HMW-DOM was then characterized for their optical properties using fluorescence spectroscopy and colloidal size spectra using asymmetrical flow field-flow fractionation techniques. Ratios of biological index (BIX) to humification index (HIX) show a seasonal change, with lower values in river open seasons and higher values under the ice, and the influence of rive discharge. Three major fluorescence DOM components were identified, including two humic-like components (Ex/Em at 260/480 nm and 250/420 nm, respectively) and one protein-like component (Ex/Em=250/330). The ratio of protein-like to humic-like components was broadly correlated with discharge, with low values during spring freshet and high values under the ice. The relatively high protein-like/humic-like ratio during the ice-covered season suggested sources from macro-organisms and/or ice-algae. Both protein-like and humic-like colloidal fluorophores were partitioned mostly in the 1-5 kDa size fraction although the protein-like fluorophores in some samples also contained larger colloidal size. The relationship between chemical/biological reactivity and size/optical characteristics of DOM needs to be further investigated.

Low molecular weight components of pollen alter bronchial epithelial barrier functions.

PubMed

Blume, Cornelia; Swindle, Emily J; Gilles, Stefanie; Traidl-Hoffmann, Claudia; Davies, Donna E

2015-01-01

The bronchial epithelium plays a key role in providing a protective barrier against many environmental substances of anthropogenic or natural origin which enter the lungs during breathing. Appropriate responses to these agents are critical for regulation of tissue homeostasis, while inappropriate responses may contribute to disease pathogenesis. Here, we compared epithelial barrier responses to different pollen species, characterized the active pollen components and the signaling pathways leading to epithelial activation. Polarized bronchial cells were exposed to extracts of timothy grass (Phleum pratense), ragweed (Ambrosia artemisifolia), mugwort (Artemisia vulgaris), birch (Betula alba) and pine (Pinus sylvestris) pollens. All pollen species caused a decrease in ionic permeability as monitored trans-epithelial electrical resistance (TER) and induced polarized release of mediators analyzed by ELISA, with grass pollen showing the highest activity. Ultrafiltration showed that the responses were due to components <3kDa. However, lipid mediators, including phytoprostane E1, had no effect on TER, and caused only modest induction of mediator release. Reverse-phase chromatography separated 2 active fractions: the most hydrophilic maximally affected cytokine release whereas the other only affected TER. Inhibitor studies revealed that JNK played a more dominant role in regulation of barrier permeability in response to grass pollen exposure, whereas ERK and p38 controlled cytokine release. Adenosine and the flavonoid isorhamnetin present in grass pollen contributed to the overall effect on airway epithelial barrier responses. In conclusion, bronchial epithelial barrier functions are differentially affected by several low molecular weight components released by pollen. Furthermore, ionic permeability and innate cytokine production are differentially regulated.

Effect of molecular weight on polymer processability

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

Karg, R.F.

1983-01-01

Differences in rheological behavior due to the polymer molecular weight and molecular weight distribution have been shown with the MPT. SBR polymers having high molecular weight fractions develop higher stress relaxation time values due to the higher degree of polymer entanglements. Tests conducted at increasing temperatures show the diminishing influence of the polymer entanglements upon stress relaxation time. EPDM polymers show stress relaxation time and head pressure behavior which correlates with mill processability. As anticipated, compounded stock of EPDM have broad molecular weight distribution has higher stress relaxation time values than EPDM compounds with narrow molecular weight distribution.

Dissolved organic matter signatures vary between naturally acidic, circumneutral and groundwater-fed freshwaters in Australia.

PubMed

Holland, Aleicia; Stauber, Jenny; Wood, Chris M; Trenfield, Melanie; Jolley, Dianne F

2018-06-15

Dissolved organic matter (DOM) plays important roles in both abiotic and biotic processes within aquatic ecosystems, and these in turn depend on the quality of the DOM. We collected and characterized chromophoric DOM (CDOM) from different Australian freshwater types (circumneutral, naturally acidic and groundwater-fed waterways), climatic regions and seasons. CDOM quality was characterized using absorbance and fluorescence spectroscopy. Excitation emission scans followed by parallel factor (PARAFAC) analysis showed that CDOM was characterized by three main components: protein-like, fulvic-like and humic-like components commonly associated with various waters globally in the Openfluor database. Principal component analysis showed that CDOM quality varied between naturally acidic, circumneutral and groundwater-fed waters, with unique CDOM quality signatures shown for each freshwater type. CDOM quality also differed significantly within some sites between seasons. Clear differences in dominant CDOM components were shown between freshwater types. Naturally acidic waters were dominated by highly aromatic (as indicated by the specific absorbance co-efficient (SAC 340 ) and the specific UV absorbance (SUVA 254 ) values which ranged between 31 and 50 cm 2  mg -1 and 3.9-5.7 mg C -1  m -1 respectively), humic-like CDOM of high molecular weight (as indicated by abs 254/365 which ranged from 3.8 to 4.3). In contrast, circumneutral waters were dominated by fulvic-like CDOM of lower aromaticity (SAC 340 : 7-21 cm 2  mg -1 and SUVA 254 : 1.5-3.0 mg C -1  m -1 ) and lower molecular weight (abs 254/365 5.1-9.3). The groundwater-fed site had a higher abundance of protein-like CDOM, which was the least aromatic (SAC 340 : 2-5 cm 2  mg -1 and SUVA 254 : 0.58-1.1 mg C -1  m -1 ). CDOM was generally less aromatic, of a lower molecular weight and more autochthonous in nature during the summer/autumn sampling compared to winter/spring. Significant relationships were shown between various CDOM quality parameters and pH. This is the first study to show that different freshwater types (circumneutral, naturally acidic and groundwater-fed) contain distinct CDOM quality signatures in Australia, a continent with unique flora and geology. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

Analysis of surface damage in retrieved carbon fiber-reinforced and plain polyethylene tibial components from posterior stabilized total knee replacements.

PubMed

Wright, T M; Rimnac, C M; Faris, P M; Bansal, M

1988-10-01

The performance of carbon fiber-reinforced ultra-high molecular weight polyethylene was compared with that of plain (non-reinforced) polyethylene on the basis of the damage that was observed on the articulating surfaces of retrieved tibial components of total knee prostheses. Established microscopy techniques for subjectively grading the presence and extent of surface damage and the histological structure of the surrounding tissues were used to evaluate twenty-six carbon fiber-reinforced and twenty plain polyethylene components that had been retrieved after an average of twenty-one months of implantation. All of the tibial components were from the same design of total knee replacement. The two groups of patients from whom the components were retrieved did not differ with regard to weight, the length of time that the component had been implanted, the radiographic position and angular alignment of the component, the original diagnosis, or the reason for removal of the component. The amounts and types of damage that were observed did not differ for the two materials. For both materials, the amount of damage was directly related to the length of time that the component had been implanted. The histological appearance of tissues from the area around the component did not differ for the two materials, except for the presence of fragments of carbon fiber in many of the samples from the areas around carbon fiber-reinforced components.

Small-scale hydrous pyrolysis of macromolecular material in meteorites

NASA Astrophysics Data System (ADS)

Sephton, M. A.; Pillinger, C. T.; Gilmour, I.

1998-12-01

The hydrous pyrolysis method, usually performed on several hundred grams of terrestrial rock sample, has been scaled down to accommodate less than two grams of meteorite sample. This technique makes full use of the high yields associated with hydrous pyrolysis experiments and permits the investigation of the meteorite macromolecular material, the major organic component in carbonaceous meteorites. The hydrous pyrolysis procedure transforms the high molecular weight macromolecular material into low molecular weight fragments. The released entities can then be extracted with supercritical fluid extraction. In contrast to the parent structure, the pyrolysis products are amenable for analysis by gas chromatography-based techniques. When subjected to hydrous pyrolysis, two carbonaceous chondrites (Orgueil and Cold Bokkeveld) released generally similar products, which consisted of abundant volatile aromatic and alkyl-substituted aromatic compounds. These results revealed the ability of small-scale hydrous pyrolysis to dissect extraterrestrial macromolecular material and thereby reveal its organic constitution.

Structure, wettability and thermal degradation of new fluoro-oligomer modified nanoclays.

PubMed

Valsecchi, R; Viganò, M; Levi, M; Turri, S

2008-04-01

Quaternary ammonium salts based on monofunctionalized Perfluoropolyether (PFPE) oligomers were synthesized and used for the cation exchange process of sodium Montmorillonite nanoclays. The new fluoromodified nanoclays were characterized through X-rays diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), termogravimetric analysis (TGA), differential scanning calorimetry (DSC), electronic microscopy (SEM-EDS), and contact angle measurements (CA). In particular XRD showed rather complex patterns (presence of higher order reflections) which allowed the calculation of basal spacings, regularly increasing with the molecular weight of the fluorinated macrocation. Both IR and SEM confirmed the presence of fluorinated segments at clays interface, while TGA showed a limited thermal stability with an onset of degradation temperature which seems not dependent on the molecular weight of the macrocation. CA measurements showed a peculiar behaviour, with evident dynamic hysteresis phenomena and surface tension components quite different from those of commercially available, organomodified clays.

Effect of Injection Molding Melt Temperatures on PLGA Craniofacial Plate Properties during In Vitro Degradation.

PubMed

de Melo, Liliane Pimenta; Salmoria, Gean Vitor; Fancello, Eduardo Alberto; Roesler, Carlos Rodrigo de Mello

2017-01-01

The purpose of this article is to present mechanical and physicochemical properties during in vitro degradation of PLGA material as craniofacial plates based on different values of injection molded temperatures. Injection molded plates were submitted to in vitro degradation in a thermostat bath at 37 ± 1°C by 16 weeks. The material was removed after 15, 30, 60, and 120 days; then bending stiffness, crystallinity, molecular weights, and viscoelasticity were studied. A significant decrease of molecular weight and mechanical properties over time and a difference in FT-IR after 60 days showed faster degradation of the material in the geometry studied. DSC analysis confirmed that the crystallization occurred, especially in higher melt temperature condition. DMA analysis suggests a greater contribution of the viscous component of higher temperature than lower temperature in thermomechanical behavior. The results suggest that physical-mechanical properties of PLGA plates among degradation differ per injection molding temperatures.

Extrudable polymer-polymer composites based on ultra-high molecular weight polyethylene

NASA Astrophysics Data System (ADS)

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.

Non-conventional approaches to food processing in CELSS. I - Algal proteins: Characterization and process optimization

NASA Technical Reports Server (NTRS)

Nakhost, Z.; Karel, M.; Krukonis, V. J.

1987-01-01

Protein isolate obtained from green algae (Scenedesmus obliquus) cultivated under controlled conditions was characterized. Molecular weight determination of fractionated algal proteins using SDS-polyacrylamide gel electrophoresis revealed a wide spectrum of molecular weights ranging from 15,000 to 220,000. Isoelectric points of dissociated proteins were in the range of 3.95 to 6.20. Amino acid composition of protein isolate compared favorably with FAO standards. High content of essential amino acids leucine, valine, phenylalanine and lysine makes algal protein isolate a high quality component of CELSS diets. To optimize the removal of algal lipids and pigments supercritical carbon dioxide extraction (with and without ethanol as a co-solvent) was used. Addition of ethanol to supercritical CO2 resulted in more efficient removal of algal lipids and produced protein isolate with a good yield and protein recovery. The protein isolate extracted by the above mixture had an improved water solubility.

Non-conventional approaches to food processing in CELSS, 1. Algal proteins: Characterization and process optimization

NASA Technical Reports Server (NTRS)

Nakhost, Z.; Karel, M.; Krukonis, V. J.

1987-01-01

Protein isolate obtained from green algae cultivated under controlled conditions was characterized. Molecular weight determination of fractionated algal proteins using SDS-polyacrylamide gel electrophoresis revealed a wide spectrum of molecular weights ranging from 15,000 to 220,000. Isoelectric points of dissociated proteins were in the range of 3.95 to 6.20. Amino acid composition of protein isolate compared favorably with FAO standards. High content of essential amino acids leucine, valine, phenylalanine and lysine make algal protein isolate a high quality component of closed ecological life support system diets. To optimize the removal of algal lipids and pigments supercritical carbon dioxide extraction (with and without ethanol as a co-solvent) was used. Addition of ethanol to supercritical carbon dioxide resulted in more efficient removal of algal lipids and produced protein isolate with a good yield and protein recovery. The protein isolate extracted by the above mixture had an improved water solubility.

[Allelic variation at high-molecular-weight glutenin subunit loci in Aegilops biuncialis Vis].

PubMed

Kozub, N A; Sozinov, I A; Ksinias, I N; Sozinov, A A

2011-09-01

Alleles at the high-molecular-weight glutenin subunit loci Glu-U1 and Glu-M(b)1 were analyzed in the tetraploid species Aegilops biuncialis (UUM(b)M(b)). The material for the investigation included the collection of 39 accessions of Ae. biuncialis from Ukraine (the Crimea), one Hellenic accession, one accession of unknown origin, F2 seeds from different crosses, as well as samples from natural populations from the Crimea. Ae. umbellulata and Ae. comosa accessions were used to allocate components of the HMW glutenin subunit patterns of Ae. biuncialis to U or M(b) genomes. Eight alleles were identified at the Glu-U1 locus and ten alleles were revealed at the Glu-M(b) 1 locus. Among alleles at the Glu-M(b) 1 locus ofAe. biuncialis there were two alleles controlling the y-type subunit only and one allele encoding the x-subunit only.

Structural Characterization of the Low-Molecular-Weight Heparin Dalteparin by Combining Different Analytical Strategies.

PubMed

Bisio, Antonella; Urso, Elena; Guerrini, Marco; de Wit, Pauline; Torri, Giangiacomo; Naggi, Annamaria

2017-06-24

A number of low molecular weight heparin (LMWH) products are available for clinical use and although all share a similar mechanism of action, they are classified as distinct drugs because of the different depolymerisation processes of the native heparin resulting in substantial pharmacokinetic and pharmacodynamics differences. While enoxaparin has been extensively investigated, little information is available regarding the LMWH dalteparin. The present study is focused on the detailed structural characterization of Fragmin ® by LC-MS and NMR applied both to the whole drug and to its enzymatic products. For a more in-depth approach, size homogeneous octasaccharide and decasaccharide components together with their fractions endowed with high or no affinity toward antithrombin were also isolated and their structural profiles characterized. The combination of different analytical strategies here described represents a useful tool for the assessment of batch-to-batch structural variability and for comparative evaluation of structural features of biosimilar products.

Studies on the oligosaccharide heterogeneity of the isoelectric forms of the lower molecular weight acid phosphatase of frog liver.

PubMed

Kubicz, A; Szalewicz, A; Chrambach, A

1991-01-01

1. The lower molecular weight, heterogeneous acid phosphatase (AcPase) from the frog liver (Rana esculenta) containing AcPase I, II, III and IV was separated into enzymatically active components by isoelectric focusing in an immobilized pH gradient. 2. The blotted enzyme bands were characterized by their different binding patterns obtained with the lectins concanavalin A, wheat germ agglutinin (WGA), Lens culinaris hemagglutinin (LcH) and peanut agglutinin (PNA). 3. In situ neuraminidase treatment reduced the staining intensity of some WGA-bands and increased that of PNA-bands. 4. The finding that AcPases I, II, III and IV differ in their carbohydrate chain composition, together with previous results showing different bioactivities of AcPases III and IV, indicates a correlation between the glycosylation state of enzyme forms and their physiological action.

The Combined Influence of Molecular Weight and Temperature on the Aging and Viscoelastic Response of a Glassy Thermoplastic Polyimide

NASA Technical Reports Server (NTRS)

Nicholson, Lee M.; Whitley, Karen S.; Gates, Thomas S.

2000-01-01

The effect of molecular weight on the viscoelastic performance of an advanced polymer (LaRC-SI) was investigated through the use of creep compliance tests. Testing consisted of short-term isothermal creep and recovery with the creep segments performed under constant load. The tests were conducted at three temperatures below the glass transition temperature of five materials of different molecular weight. Through the use of time-aging-time superposition procedures, the material constants, material master curves and aging-related parameters were evaluated at each temperature for a given molecular weight. The time-temperature superposition technique helped to describe the effect of temperature on the timescale of the viscoelastic response of each molecular weight. It was shown that the low molecular weight materials have higher creep compliance and creep rate, and are more sensitive to temperature than the high molecular weight materials. Furthermore, a critical molecular weight transition was observed to occur at a weight-average molecular weight of M (bar) (sub w) 25000 g/mol below which, the temperature sensitivity of the time-temperature superposition shift factor increases rapidly. The short-term creep compliance data were used in association with Struik's effective time theory to predict the long-term creep compliance behavior for the different molecular weights. At long timescales, physical aging serves to significantly decrease the creep compliance and creep rate of all the materials tested.

Conversion of calibration curves for accurate estimation of molecular weight averages and distributions of polyether polyols by conventional size exclusion chromatography.

PubMed

Xu, Xiuqing; Yang, Xiuhan; Martin, Steven J; Mes, Edwin; Chen, Junlan; Meunier, David M

2018-08-17

Accurate measurement of molecular weight averages (M¯ n, M¯ w, M¯ z ) and molecular weight distributions (MWD) of polyether polyols by conventional SEC (size exclusion chromatography) is not as straightforward as it would appear. Conventional calibration with polystyrene (PS) standards can only provide PS apparent molecular weights which do not provide accurate estimates of polyol molecular weights. Using polyethylene oxide/polyethylene glycol (PEO/PEG) for molecular weight calibration could improve the accuracy, but the retention behavior of PEO/PEG is not stable in THF-based (tetrahydrofuran) SEC systems. In this work, two approaches for calibration curve conversion with narrow PS and polyol molecular weight standards were developed. Equations to convert PS-apparent molecular weight to polyol-apparent molecular weight were developed using both a rigorous mathematical analysis and graphical plot regression method. The conversion equations obtained by the two approaches were in good agreement. Factors influencing the conversion equation were investigated. It was concluded that the separation conditions such as column batch and operating temperature did not have significant impact on the conversion coefficients and a universal conversion equation could be obtained. With this conversion equation, more accurate estimates of molecular weight averages and MWDs for polyether polyols can be achieved from conventional PS-THF SEC calibration. Moreover, no additional experimentation is required to convert historical PS equivalent data to reasonably accurate molecular weight results. Copyright © 2018. Published by Elsevier B.V.

From oligomers to molecular giants of soybean oil in supercritical carbon dioxide medium: 1. Preparation of polymers with lower molecular weight from soybean oil.

PubMed

Liu, Zengshe; Sharma, Brajendra K; Erhan, Sevim Z

2007-01-01

Polymers with a low molecular weight derived from soybean oil have been prepared in a supercritical carbon dioxide medium by cationic polymerization. Boron trifluoride diethyl etherate was used as an initiator. Influences of polymerization temperature, amount of initiator, and carbon dioxide pressure on the molecular weight were investigated. It is shown that the higher polymerization temperature favors polymers with relatively higher molecular weights. Larger amounts of initiator also provide polymers with higher molecular weights. Higher pressure favors polymers with relatively higher molecular weights. The applications of these soy-based materials will be in the lubrication and hydraulic fluid areas.

PEEK-OPTIMA™ as an alternative to cobalt chrome in the femoral component of total knee replacement: A preliminary study

PubMed Central

Cowie, Raelene M; Briscoe, Adam; Fisher, John; Jennings, Louise M

2016-01-01

PEEK-OPTIMA™ (Invibio Ltd, UK) has been considered as an alternative joint arthroplasty bearing material due to its favourable mechanical properties and the biocompatibility of its wear debris. In this study, the potential to use injection moulded PEEK-OPTIMA™ as an alternative to cobalt chrome in the femoral component of a total knee replacement was investigated in terms of its wear performance. Experimental wear simulation of three cobalt chrome and three PEEK-OPTIMA™ femoral components articulating against all-polyethylene tibial components was carried out under two kinematic conditions: 3 million cycles under intermediate kinematics (maximum anterior-posterior displacement of 5 mm) followed by 3 million cycles under high kinematic conditions (anterior-posterior displacement 10 mm). The wear of the GUR1020 ultra-high-molecular-weight polyethylene tibial components was assessed by gravimetric analysis; for both material combinations under each kinematic condition, the mean wear rates were low, that is, below 5 mm3/million cycles. Specifically, under intermediate kinematic conditions, the wear rate of the ultra-high-molecular-weight polyethylene tibial components was 0.96 ± 2.26 mm3/million cycles and 2.44 ± 0.78 mm3/million cycle against cobalt chrome and PEEK-OPTIMA™ implants, respectively (p = 0.06); under high kinematic conditions, the wear rates were 2.23 ± 1.85 mm3/million cycles and 4.44 ± 2.35 mm3/million cycles, respectively (p = 0.03). Following wear simulation, scratches were apparent on the surface of the PEEK-OPTIMA™ femoral components. The surface topography of the femoral components was assessed using contacting profilometry and showed a statistically significant increase in measured surface roughness of the PEEK-OPTIMA™ femoral components compared to the cobalt chrome implants. However, this did not appear to influence the wear rate, which remained linear over the duration of the study. These preliminary findings showed that PEEK-OPTIMA™ gives promise as an alternative bearing material to cobalt chrome alloy in the femoral component of a total knee replacement with respect to wear performance. PMID:27637723

Distribution of molecular weight in glyceride polymerizates or aggregates of them after contact with lunar grains

NASA Technical Reports Server (NTRS)

Asunmaa, S. K.; Haack, R.

1977-01-01

An attempt is made to report on experiments in which a molecular-weight increase was determined in thin layers of triglyceride-containing glycerides after thin-layer contact for two years with lunar topsoil grains at 25 C without any thermal activation. It is noted that solidification was observed on both dielectric grains and metal-rich areas and that changes in viscosity and molecular weights were first detected by solidification of surface layers. Gel permeation chromatography is described which detected a general shift of the Gaussian distribution of the molecular-weight data toward generally higher molecular weights as well as an increase in mean molecular weight. Reaction mechanisms are considered, and results of spectrographic analysis are cited which support the interpretations of the molecular-weight data.

Hyaluronan influence on the onset of chondrogenic differentiation of mesenchymal stem cells.

PubMed

Dvorakova, Jana; Velebny, Vladimir; Kubala, Lukas

2008-10-01

Hyaluronan (HA) is an abundant component of chondrogenic tissue hence it is often used as a fundamental constituent in cartilage tissue substitutes. However, effects of different molecular weight HA on chondrogenic differentiation are not clear. The aim was to evaluate modulation of mesenchymal stem cell (MSC) early chondrogenesis by HA of molecular weights 100, 600 and 1 500 kDa. HA was applied on MSCs cultured in a pellet system for one, two and three weeks. Chondrogenesis was evaluated by determinations of gene expression of transcription factor Sox-9 and extracellular matrix proteins collagen type II and XI, aggrecan, and COMP by Real-Time PCR and completed with histological analysis. Upon chondrogenic induction, the respective pellets revealed active transcription of the chondrogenic genes together with proceeding accumulation of glycosaminoglycan (GAG) rich extracellular matrix. Sox-9 was also expressed in non-chondrogenic MSC controls. HA treated pellets were not significantly influenced on day 7 of culture. However, on day 14, lowered expression in some of the extracellular matrix proteins appeared together with a moderately smaller amount of GAG content in pellet sections. Nevertheless, the analysis on day 21 has demonstrated that HA did not affect the outcome of the differentiation by the end of the culture. Any difference regarding the molecular weight of the HA was not found. It could be speculated that HA induced a time shift in the phase of the dominant matrix protein onset which was in full compensated by the end of the evaluated time period. Thus, data suggest that HA of any tested molecular weight does not significantly modulate chondrogenesis of MSCs in pellet system.

Revealing Sources and Distribution Changes of Dissolved Organic Matter (DOM) in Pore Water of Sediment from the Yangtze Estuary

PubMed Central

Wang, Ying; Zhang, Di; Shen, Zhenyao; Feng, Chenghong; Chen, Jing

2013-01-01

Dissolved organic matter (DOM) in sediment pore waters from Yangtze estuary of China based on abundance, UV absorbance, molecular weight distribution and fluorescence were investigated using a combination of various parameters of DOM as well as 3D fluorescence excitation emission matrix spectra (F-EEMS) with the parallel factor and principal component analysis (PARAFAC-PCA). The results indicated that DOM in pore water of Yangtze estuary was very variable which mainly composed of low aromaticity and molecular weight materials. Three humic-like substances (C1, C2, C4) and one protein-like substance (C3) were identified by PARAFAC model. C1, C2 and C4 exhibited same trends and were very similar. The separation of samples on both axes of the PCA showed the difference in DOM properties. C1, C2 and C4 concurrently showed higher positive factor 1 loadings, while C3 showed highly positive factor 2 loadings. The PCA analysis showed a combination contribution of microbial DOM signal and terrestrial DOM signal in the Yangtze estuary. Higher and more variable DOM abundance, aromaticity and molecular weight of surface sediment pore water DOM can be found in the southern nearshore than the other regions primarily due to the influence of frequent and intensive human activities and tributaries inflow in this area. The DOM abundance, aromaticity, molecular weight and fluorescence intensity in core of different depth were relative constant and increased gradually with depth. DOM in core was mainly composed of humic-like material, which was due to higher release of the sedimentary organic material into the porewater during early diagenesis. PMID:24155904

Venom gland transcriptomic and venom proteomic analyses of the scorpion Megacormus gertschi Díaz-Najera, 1966 (Scorpiones: Euscorpiidae: Megacorminae).

PubMed

Santibáñez-López, Carlos E; Cid-Uribe, Jimena I; Zamudio, Fernando Z; Batista, Cesar V F; Ortiz, Ernesto; Possani, Lourival D

2017-07-01

The soluble venom from the Mexican scorpion Megacormus gertschi of the family Euscorpiidae was obtained and its biological effects were tested in several animal models. This venom is not toxic to mice at doses of 100 μg per 20 g of mouse weight, while being lethal to arthropods (insects and crustaceans), at doses of 20 μg (for crickets) and 100 μg (for shrimps) per animal. Samples of the venom were separated by high performance liquid chromatography and circa 80 distinct chromatographic fractions were obtained from which 67 components have had their molecular weights determined by mass spectrometry analysis. The N-terminal amino acid sequence of seven protein/peptides were obtained by Edman degradation and are reported. Among the high molecular weight components there are enzymes with experimentally-confirmed phospholipase activity. A pair of telsons from this scorpion species was dissected, from which total RNA was extracted and used for cDNA library construction. Massive sequencing by the Illumina protocol, followed by de novo assembly, resulted in a total of 110,528 transcripts. From those, we were able to annotate 182, which putatively code for peptides/proteins with sequence similarity to previously-reported venom components available from different protein databases. Transcripts seemingly coding for enzymes showed the richest diversity, with 52 sequences putatively coding for proteases, 20 for phospholipases, 8 for lipases and 5 for hyaluronidases. The number of different transcripts potentially coding for peptides with sequence similarity to those that affect ion channels was 19, for putative antimicrobial peptides 19, and for protease inhibitor-like peptides, 18. Transcripts seemingly coding for other venom components were identified and described. The LC/MS analysis of a trypsin-digested venom aliquot resulted in 23 matches with the translated transcriptome database, which validates the transcriptome. The proteomic and transcriptomic analyses reported here constitute the first approach to study the venom components from a scorpion species belonging to the family Euscorpiidae. The data certainly show that this venom is different from all the ones described thus far in the literature. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of molecular weight on polyphenylquinoxaline properties

NASA Technical Reports Server (NTRS)

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.

Method for Making High Molecular Weight, Extended pi-Conjugated Polymers

DTIC Science & Technology

2001-05-04

derivatized poly(terephthalates)s as coatings for electronics components, and as construction materials for field- effect transistors, both applications...mannose, dulose, idose, galactose and talose; ketoses such as erythrulose, ribulose, xylulose, psicose, fructose, sorbose, tagatose ; di-, tri-, 12...show that Sc(OTr)3 alone was not effective as a 15 polymerization catalyst. When the organic salt was introduced, Sc(OTr)3 became marginally

Thermal Cracking of Tars in a Continuously Fed Reactor with Steam

DTIC Science & Technology

2011-05-01

Fluidized Bed using biomass 8 Tars  Mixture of organic components present in gasification product gas with high molecular weight hydrocarbons [MW...Disable sulfur removal systems FoulingPlugging [Ref. 3: Biomass Gasification – Tar and Particles in Product Gases Sampling and Analysis”, European...P., and Nussbaumer T., “Gas Cleaning Requirements for Internal Combustion Engine Applications of Fixed Bed Biomass Gasification ”, Biomass and

Air Quality Management Using Pollution Prevention: A Joint Service Approach

DTIC Science & Technology

1998-03-01

sites to promote polymerization. High solids coatings may be one or two component systems based on acrylic , alkyd , epoxy, polyester, or urethane...formulation to form high molecular weight polymers. Examples include acrylic , epoxy/polyester hybrid , functional epoxy, thin film epoxy, and urethane...Air Human System Center (HSC/OEBQ) Naval Facilities Engineering Service Center (NFESC) 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 9

Biomarkers for ragwort poisoning in horses: identification of protein targets

PubMed Central

Moore, Rowan E; Knottenbelt, Derek; Matthews, Jacqueline B; Beynon, Robert J; Whitfield, Phillip D

2008-01-01

Background Ingestion of the poisonous weed ragwort (Senecio jacobea) by horses leads to irreversible liver damage. The principal toxins of ragwort are the pyrrolizidine alkaloids that are rapidly metabolised to highly reactive and cytotoxic pyrroles, which can escape into the circulation and bind to proteins. In this study a non-invasive in vitro model system has been developed to investigate whether pyrrole toxins induce specific modifications of equine blood proteins that are detectable by proteomic methods. Results One dimensional gel electrophoresis revealed a significant alteration in the equine plasma protein profile following pyrrole exposure and the formation of a high molecular weight protein aggregate. Using mass spectrometry and confirmation by western blotting the major components of this aggregate were identified as fibrinogen, serum albumin and transferrin. Conclusion These findings demonstrate that pyrrolic metabolites can modify equine plasma proteins. The high molecular weight aggregate may result from extensive inter- and intra-molecular cross-linking of fibrinogen with the pyrrole. This model has the potential to form the basis of a novel proteomic strategy aimed at identifying surrogate protein biomarkers of ragwort exposure in horses and other livestock. PMID:18691403

Changes in chemical components in the freshwater apple snail, Pomacea canaliculata (Gastropoda: Ampullariidae), in relation to the development of its cold hardiness.

PubMed

Matsukura, Keiichiro; Tsumuki, Hisaaki; Izumi, Yohei; Wada, Takashi

2008-04-01

The apple snail, Pomacea canaliculata, is an invasive freshwater snail. It increases its cold hardiness before winter. However, the physiological mechanism of cold hardiness in molluscs is poorly understood, especially in freshwater molluscs. In this study, we examined the changes in low molecular weight compounds, glycogen and lipids, in the body of P. canaliculata in association with the development of cold hardiness. When snails without cold hardiness were experimentally cold-acclimated, the amount of glycerol, glutamine, and carnosine increased, while glycogen and phenylalanine decreased. Overwintering cold-tolerant snails collected from a drained paddy field in November also showed increased glycerol in their bodies with decreasing glycogen concentration, compared to summer snails collected from a submerged field. Water content also decreased during the cold acclimation, although the water loss was minimal. These results indicate that the freshwater snail, P. canaliculata enhances cold hardiness by accumulation of some kinds of low molecular weight compounds in its body as some insects do. However, the actual function of each low molecular compound is still unknown.

Nanowires formed by the co-assembly of a negatively charged low-molecular weight gelator and a zwitterionic polythiophene.

PubMed

Li, Feng; Palaniswamy, Ganesan; de Jong, Menno R; Aslund, Andreas; Konradsson, Peter; Marcelis, Antonius T M; Sudhölter, Ernst J R; Stuart, Martien A Cohen; Leermakers, Frans A M

2010-06-21

Conjugated organic nanowires have been prepared by co-assembling a carboxylate containing low-molecular weight gelator (LMWG) and an amino acid substituted polythiophene derivative (PTT). Upon introducing the zwitterionic polyelectrolyte PTT to a basic molecular solution of the organogelator, the negative charges on the LMWG are compensated by the positive charges of the PTT. As a result, nanowires form through co-assembly. These nanowires are visualized by both transmission electron microscopy (TEM) and atomic force microscopy (AFM). Depending on the concentration and ratio of the components these nanowires can be micrometers long. These measurements further suggest that the aggregates adopt a helical conformation. The morphology of these nanowires are studied with fluorescent confocal laser scanning microscopy (CLSM). The interactions between LMWG and PTT are characterized by steady-state and time-resolved fluorescence spectroscopy studies. The steady-state spectra indicate that the backbone of the PTT adopts a more planar and more aggregated conformation when interacting with LMWG. The time- resolved fluorescence decay studies confirm this interpretation.

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

ERIC Educational Resources Information Center

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…

Molecular Weight and Molecular Weight Distributions in Synthetic Polymers.

ERIC Educational Resources Information Center

Ward, Thomas Carl

1981-01-01

Focuses on molecular weight and molecular weight distributions (MWD) and models for predicting MWD in a pedagogical way. In addition, instrumental methods used to characterize MWD are reviewed with emphasis on physical chemistry of each, including end-group determination, osmometry, light scattering, solution viscosity, fractionation, and…

Tunable Affinity and Molecular Architecture Lead to Diverse Self-Assembled Supramolecular Structures in Thin Films

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

Hsu, Chih-Hao; Dong, Xue-Hui; Lin, Zhiwei

2015-12-03

The self-assembly behaviors of specifically designed giant surfactants are systematically studied in thin films using grazing incident X-ray and transmission electron microscopy (TEM), focusing on the effects of head surface functionalities and molecular architectures on nanostructure formation. Two molecular nanoparticles (MNPs) with different affinities, i.e., hydrophilic carboxylic acid functionalized [60]fullerene (AC60) and omniphobic fluorinated polyhedral oligomeric silsesquioxane (FPOSS), are utilized as heads of the giant surfactants. By covalently tethering these functional MNPs onto the chain end or the junction point of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymer, linear and star-like giant surfactants possess distinct molecular architectures are constructed. With fixed lengthmore » of the PEO block, the molecular weight change of the PS block originates the phase formation and transition. Due to the distinct affinity, the AC60-based giant surfactants form two-component morphologies, while three-component morphologies are found in the FPOSS-based ones. A PS block stretching parameter is introduced to characterize the PS chain conformation in different morphologies. The highly diverse self-assembly behaviors and the tunable dimensions in thin films suggest the giant surfactants could be a promising and robust platform for nanolithography applications.« less

Molecular beam scattering from C-13 enriched Kapton and correlation with the EOIM-3 carousel experiment

NASA Technical Reports Server (NTRS)

Minton, Timothy K.; Moore, Teresa A.

1995-01-01

Mass spectra of products emerging from identical samples of a C-13-enriched polyimide polymer (chemically equivalent to Kapton) under atomic oxygen bombardment in space and in the laboratory were collected. Reaction products unambiguously detected in space were CO-13, NO, (12)CO2, and (13)CO2. These reaction products and two others, H2O and CO-12, were detected in the laboratory, along with inelastically scattered atomic and molecular oxygen. Qualitative agreement was seen in the mass spectra taken in space and in the laboratory; the agreement may be improved by reducing the fraction of O2 in the laboratory molecular beam. Both laboratory and space data indicated that CO and CO2 products come preferentially from reaction with the imide component of the polymer chain, raising the possibility that the either component may degrade in part by the 'evaporation' of higher molecular weight fragments. Laboratory time-of-flight distributions showed: (1) incomplete energy accommodation of impinging O and O2 species that do not react with the surface; and (2) both hyperthermal and thermal CO and CO2 products, suggesting two distinct reaction mechanisms with the surface.

Ozonation effects on emerging micropollutants and effluent organic matter in wastewater: characterization using changes of three-dimensional HP-SEC and EEM fluorescence data.

PubMed

Liu, Chen; Li, Penghui; Tang, Xiangyu; Korshin, Gregory V

2016-10-01

The degradation of effluent organic matter (EfOM) in a municipal wastewater treated by ozonation was characterized using the methods of high-performance size-exclusion chromatography (HP-SEC) and excitation/emission matrix (EEM) fluorescence combined with parallel factor analysis (PARAFAC). The removal of 40 diverse trace-level contaminants of emerging concern (CEC) present in the wastewater was determined as well. Ozonation caused a rapid decrease of the absorbance and fluorescence of the wastewater, which was associated primarily with the oxidation of high and low apparent molecular weight (AMW) EfOM fractions. PARAFAC analysis also showed that components C1 and C2 decreased prominently in these conditions. The EfOM fraction of intermediate molecular weight ascribable to a terrestrial humic-like component (C3) tended to be less reactive toward ozone. Relative changes of EEM fluorescence were quantified using F max values of PARAFAC-identified components (∆F/F 0 max ). Unambiguous relationships between ∆F/F 0 max values and the extent of the degradation of the examined CECs (∆C/C 0 ) were established. This allowed correlating main parameters of the ∆C/C 0 vs. ∆F/F 0 max relationships with the rates of oxidation of these CECs. The results demonstrate the potential of online measurements of EEM fluorescence for quantitating effects of ozonation on EfOM and micropollutants in wastewater effluents.

Uniaxial drawing and mechanical properties of poly[(R)-3-hydroxybutyrate]/poly(L-lactic acid) blends.

PubMed

Park, Jun Wuk; Doi, Yoshiharu; Iwata, Tadahisa

2004-01-01

Blends of poly(L-lactic acid) (PLLA) with two kinds of poly[(R)-3-hydroxybutyrate] (PHB) having different molecular weights, commercial-grade bacterial PHB (bacterial-PHB) and ultrahigh molecular weight PHB (UHMW-PHB), were prepared by the solvent-casting method and uniaxially drawn at two drawing temperatures, around PHB's T(g) (2 degrees C) for PHB-rich blends and around PLLA's T(g) (60 degrees C) for PLLA-rich blends. Differential scanning calorimetry analysis showed that this system was immiscible over the entire composition range. Mechanical properties of all of the samples were improved in proportion to the draw ratio. Although PLLA domains in bacterial-PHB-rich blends remained almost unstretched during cold drawing, a good interfacial adhesion between two polymers and the reinforcing role of PLLA components led to enhanced mechanical properties proportionally to the PLLA content at the same draw ratio. On the contrary, in the case of UHMW-PHB-rich blends, the minor component PLLA was found to be also oriented by cold drawing in ice water due to an increase in the interfacial entanglements caused by the very long chain length of the matrix polymer. As a result, their mechanical properties were considerably improved with increasing PLLA content compared with the bacterial-PHB system. Scanning electron microscopy observations on the surface and cross-section revealed that a layered structure with uniformly oriented microporous in the interior was obtained by selectively removal of PLLA component after simple alkaline treatment.

Mechanical Properties of LaRC(tm) SI Polymer for a Range of Molecular Weights

NASA Technical Reports Server (NTRS)

Whitley, Karen S.; Gates, Thomas S.; Hinkley, Jeffrey A.; Nicholson, Lee M.

2000-01-01

Mechanical testing of an advanced polyimide resin (LaRC(tm)-SI) with known variations in molecular weight was performed over a range of temperatures below the glass transition temperature. Elastic and inelastic properties were characterized as a function of molecular weight and test temperature. It was shown that notched tensile strength is a strong function of both temperature and molecular weight, whereas stiffness is only a strong function of temperature. The combined analysis of calculated yield stress and notched tensile strength indicated that low molecular weight materials tended to fail in a brittle manner, whereas high molecular weight materials exhibited ductile failure. The microphotographs of the failure surfaces also supported these findings.

Perchlorate-induced combustion of organic matter with variable molecular weights: Implications for Mars missions

NASA Astrophysics Data System (ADS)

Sephton, Mark A.; Lewis, James M. T.; Watson, Jonathan S.; Montgomery, Wren; Garnier, Carole

2014-11-01

Instruments on the Viking landers and Curiosity rover analyzed samples of Mars and detected carbon dioxide and organic compounds of uncertain origin. Mineral-assisted reactions are leading to uncertainty, particularly those involving perchlorate minerals which thermally decompose to produce chlorine and oxygen which can then react with organic matter to generate organochlorine compounds and carbon dioxide. Although generally considered a problem for interpretation, the release profiles of generated gases can indicate the type of organic matter present. We have performed a set of experiments with perchlorate and organic matter of variable molecular weights. Results indicate that organic susceptibility to thermal degradation and mineral-assisted reactions is related to molecular weight. Low molecular weight organic matter reacts at lower temperatures than its high molecular weight counterparts. The natural occurrence and association of organic matter with differing molecular weights helps to discriminate between contamination (usually low molecular weight organic matter only) and indigenous carbon (commonly low and high molecular weight organic matter together). Our results can be used to provide insights into data returning from Mars.

Peptidylation for the determination of low-molecular-weight compounds by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

PubMed

Tang, Feng; Cen, Si-Ying; He, Huan; Liu, Yi; Yuan, Bi-Feng; Feng, Yu-Qi

2016-05-23

Determination of low-molecular-weight compounds by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has been a great challenge in the analytical research field. Here we developed a universal peptide-based derivatization (peptidylation) strategy for the sensitive analysis of low-molecular-weight compounds by MALDI-TOF-MS. Upon peptidylation, the molecular weights of target analytes increase, thus avoiding serious matrix ion interference in the low-molecular-weight region in MALDI-TOF-MS. Since peptides typically exhibit good signal response during MALDI-TOF-MS analysis, peptidylation endows high detection sensitivities of low-molecular-weight analytes. As a proof-of-concept, we analyzed low-molecular-weight compounds of aldehydes and thiols by the developed peptidylation strategy. Our results showed that aldehydes and thiols can be readily determined upon peptidylation, thus realizing the sensitive and efficient determination of low-molecular-weight compounds by MALDI-TOF-MS. Moreover, target analytes also can be unambiguously detected in biological samples using the peptidylation strategy. The established peptidylation strategy is a universal strategy and can be extended to the sensitive analysis of various low-molecular-weight compounds by MALDI-TOF-MS, which may be potentially used in areas such as metabolomics.

Isolation of a thermophilic bacterium capable of low-molecular-weight polyethylene degradation.

PubMed

Jeon, Hyun Jeong; Kim, Mal Nam

2013-02-01

A thermophilic bacterium capable of low-molecular-weight polyethylene (LMWPE) degradation was isolated from a compost sample, and was identified as Chelatococcus sp. E1, through sequencing of the 16S rRNA gene. LMWPE was prepared by thermal degradation of commercial PE in a strict nitrogen atmosphere. LMWPE with a weight-average-molecular-weight (Mw) in the range of 1,700-23,700 was noticeably mineralized into CO(2) by the bacterium. The biodegradability of LMWPE decreased as the Mw increased. The low molecular weight fraction of LMWPE decreased significantly as a result of the degradation process, and thereby both the number-average-molecular-weight and Mw increased after biodegradation. The polydispersity of LMWPE was either narrowed or widened, depending on the initial Mw of LMWPE, due to the preferential elimination of the low molecular weight fraction, in comparison to the high molecular weight portion. LMWPE free from an extremely low molecular weight fraction was also mineralized by the strain at a remarkable rate, and FTIR peaks assignable to C-O stretching appeared as a result of microbial action. The FTIR peaks corresponding to alkenes also became more intense, indicating that dehydrogenations occurred concomitantly with microbial induced oxidation.

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

PubMed

Morioka, Takako; Shibata, Osamu; Kawaguchi, Masami

2010-12-07

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

Rheology modification with ring polymers

NASA Astrophysics Data System (ADS)

Vlassopoulos, Dimitris

It is now established that experimental unconcatenated ring polymers can be purified effectively by means of fractionation at the critical condition. For molecular weights well above the entanglement threshold, purified rings relax stress via power-law (with an exponent of about -0.4), sharply departing from their linear counterparts. Experimental results are in harmony with modeling predictions and simulations. Here, we present results from recent interdisciplinary efforts and discuss two challenges: (i) the nonlinear shear rheology of purified ring melts is also very different from that of unlinked chains. Whereas the latter exhibit features that can be explained, to a first approach, in the framework in the tube model, the former behave akin to unentangled chains with finite extensibility and exhibit much small deformation at steady state. (ii) blends of rings and linear polymers exhibit unique features in different regimes: The addition of minute amounts of linear chains drastically affects ring dynamics. This relates to ring purity and the ability of unlinked linear chains to thread rings. With the help of simulations, it is possible to rationalize the observed surprisingly slow viscoelastic relaxation, which is attributed to ring-linear and ring-ring penetrations. On the other hand, adding small amounts of rings to linear polymers of different molecular weights influences their linear and nonlinear rheology in an unprecedented way. The blend viscosity exceeds that of the slower component (linear) in this non-interacting mixture, and its dependencies on composition and molecular weight ratio are examined, whereas the role of molecular architecture is also addressed. Consequently, closing the ends of a linear chain can serve as a powerful means for molecular manipulation of its rheology. This presentation reflects collaborative efforts with S. Costanzo, Z-C. Yan, R. Pasquino, M. Kaliva, S. Kamble, Y. Jeong, P. Lutz, J. Allgaier, T. Chang, D. Talikis, V. Mavrantzas and M. Rubinstein.

Myosin: A Link between Streptococci and Heart

NASA Astrophysics Data System (ADS)

Krisher, Karen; Cunningham, Madeleine W.

1985-01-01

Murine monoclonal antibodies to Streptococcus pyogenes reacted with skeletal muscle myosin. High molecular weight proteins in extracts of human heart tissue that reacted with an antibody to S. pyogenes also reacted with a monoclonal antibody to ventricular myosin. Adsorption of the antibody to streptococci with S. pyogenes simultaneously removed reactivity of the antibody for either S. pyogenes or myosin. These results indicate that myosin shares immunodeterminants with a component of S. pyogenes.

Qualitative and Quantitative Analysis of Proteome and Peptidome of Human Follicular Fluid Using Multiple Samples from Single Donor with LC-MS and SWATH Methodology.

PubMed

Lewandowska, Aleksandra E; Macur, Katarzyna; Czaplewska, Paulina; Liss, Joanna; Łukaszuk, Krzysztof; Ołdziej, Stanisław

2017-08-04

Human follicular fluid (hFF) is a natural environment of oocyte maturation, and some components of hFF could be used to judge oocyte capability for fertilization and further development. In our pilot small-scale study three samples from four donors (12 samples in total) were analyzed to determine which hFF proteins/peptides could be used to differentiate individual oocytes and which are patient-specific. Ultrafiltration was used to fractionate hFF to high-molecular-weight (HMW) proteome (>10 kDa) and low-molecular-weight (LMW) peptidome (<10 kDa) fractions. HMW and LMW compositions were analyzed using LC-MS in SWATH data acquisition and processing methodology. In total we were able to identify 158 proteins, from which 59 were never reported before as hFF components. 55 (45 not reported before) proteins were found by analyzing LMW fraction, 67 (14 not reported before) were found by analyzing HMW fraction, and 36 were identified in both fractions of hFF. We were able to perform quantitative analysis for 72 proteins from HMW fraction of hFF. We found that concentrations of 11 proteins varied substantially among hFF samples from single donors, and those proteins are promising targets to identify biomarkers useful in oocyte quality assessment.

Modification of Pectin and Hemicellulose Polysaccharides in Relation to Aril Breakdown of Harvested Longan Fruit

PubMed Central

Wang, Duoduo; Zhang, Haiyan; Wu, Fuwang; Li, Taotao; Liang, Yuxiang; Duan, Xuewu

2013-01-01

To investigate the modification of cell wall polysaccharides in relation to aril breakdown in harvested longan fruit, three pectin fractions (WSP, water soluble pectin; CSP, CDTA-soluble pectin; ASP, alkali soluble pectin) and one hemicellulose fraction (4 M KOH-SHC, 4 M KOH-soluble hemicellulose) were extracted, and their contents, monosaccharide compositions and molecular weights were evaluated. As aril breakdown intensified, CSP content increased while ASP and 4 M KOH-SHC contents decreased, suggesting the solubilization and conversion of cell wall components. Furthermore, the molar percentage of arabinose (Ara), as the main component of the side-chains, decreased largely in CSP and ASP while that of rhamnose (Rha), as branch point for the attachment of neutral sugar side chains, increased during aril breakdown. Analysis of (Ara + Gal)/Rha ratio showed that the depolymerization of CSP and ASP happened predominantly in side-chains formed of Ara residues. For 4 M KOH-SHC, more backbones were depolymerized during aril breakdown. Moreover, it was found that the molecular weights of CSP, ASP and 4 M KOH-SHC polysaccharides tended to decrease as aril breakdown intensified. These results suggest that both enhanced depolymerization and structural modifications of polysaccharides in the CSP, ASP and 4 M KOH-SHC fractions might be responsible for aril breakdown of harvested longan fruit. PMID:24287911

Characterization of humic substances in landfill leachate and impact on the hydraulic conductivity of geosynthetic clay liners.

PubMed

Han, Young-Soo; Lee, Jai-Young; Miller, Carol J; Franklin, Lance

2009-05-01

A detailed characterization was performed on the humic substances present in landfill leachate derived from the older (10-year) and younger (6-month) municipal landfill cells at a site in Inchion, Korea. The characterization focused on the humic and fulvic acid components of the leachate, relying on information gleaned from the UV/visible spectroscopy, molecular weight distribution, and Fourier transform infrared spectroscopy. The effect of the leachates, and specific components of the leachates, on the hydraulic conductivity of a geosynthetic clay liner (GCL), was evaluated. The humic acid extracted from the older leachate was composed primarily of high molecular weight and aromatic compounds, which is typical for humic acids. However, the humic acid extracted from the younger leachate showed characteristics more similar with fulvic acids, indicating that the younger humic acid was at the initial stage of humification. The hydraulic conductivity of the GCLs to the humic and fulvic acids of the older and younger leachate was similar to those permeated with the distilled deionized water (DI). However, the hydraulic conductivity of the samples tested with the raw leachate was more than 200 times the DI value. This fact suggests that cations present in leachate, rather than humic substances, are the key factor in the increase of the permeability.

Effect of Sulfation and Molecular Weight on Anticoagulant Activity of Dextran.

PubMed

Drozd, N N; Logvinova, Yu S; Torlopov, M A; Udoratina, E V

2017-02-01

Sulfation (to 2.8) of dextrans with molecular weight of 150 and 20 kDa was followed by the appearance of anticoagulant activity that increased with decreasing their molecular weight and did not depend on antithrombin, plasma inhibitor of serine proteases of the blood coagulation system. Antithrombin activity of dextran sulfate with a molecular weight of 20 kDa reached 12.6-15.3 U/mg. Dextran sulfates with molecular weights of 20 and 150 kDa did not potentiate ADP-induced human platelet aggregation.

Determination of the absolute molecular weight averages and molecular weight distributions of alginates used as ice cream stabilizers by using multiangle laser light scattering measurements.

PubMed

Turquois, T; Gloria, H

2000-11-01

High-performance size exclusion chromatography with multiangle laser light scattering detection (HPSEC-MALLS) was used for characterizing complete molecular weight distributions for a range of commercial alginates used as ice cream stabilizers. For the samples investigated, molecular weight averages were found to vary between 115 000 and 321 700 g/mol and polydispersity indexes varied from 1. 53 to 3.25. These samples displayed a high content of low molecular weights. Thus, the weight percentage of material below 100 000 g/mol ranged between 6.9 and 54.4%.

In vivo, Argonaute-bound microRNAs exist predominantly in a reservoir of low molecular weight complexes not associated with mRNA

PubMed Central

La Rocca, Gaspare; Olejniczak, Scott H.; González, Alvaro J.; Briskin, Daniel; Vidigal, Joana A.; Spraggon, Lee; DeMatteo, Raymond G.; Radler, Megan R.; Lindsten, Tullia; Ventura, Andrea; Tuschl, Thomas; Leslie, Christina S.; Thompson, Craig B.

2015-01-01

MicroRNAs repress mRNA translation by guiding Argonaute proteins to partially complementary binding sites, primarily within the 3′ untranslated region (UTR) of target mRNAs. In cell lines, Argonaute-bound microRNAs exist mainly in high molecular weight RNA-induced silencing complexes (HMW-RISC) associated with target mRNA. Here we demonstrate that most adult tissues contain reservoirs of microRNAs in low molecular weight RISC (LMW-RISC) not bound to mRNA, suggesting that these microRNAs are not actively engaged in target repression. Consistent with this observation, the majority of individual microRNAs in primary T cells were enriched in LMW-RISC. During T-cell activation, signal transduction through the phosphoinositide-3 kinase–RAC-alpha serine/threonine-protein kinase–mechanistic target of rapamycin pathway increased the assembly of microRNAs into HMW-RISC, enhanced expression of the glycine-tryptophan protein of 182 kDa, an essential component of HMW-RISC, and improved the ability of microRNAs to repress partially complementary reporters, even when expression of targeting microRNAs did not increase. Overall, data presented here demonstrate that microRNA-mediated target repression in nontransformed cells depends not only on abundance of specific microRNAs, but also on regulation of RISC assembly by intracellular signaling. PMID:25568082

Enzymatic hydrolysis of Grass Carp fish skin hydrolysates able to promote the proliferation of Streptococcus thermophilus.

PubMed

Wang, Xiao-Nan; Qin, Mei; Feng, Yu-Ying; Chen, Jian-Kang; Song, Yi-Shan

2017-09-01

The promotion effect on proliferation of Streptococcus thermophilus by enzymatic hydrolysates of aquatic products was firstly studied. The effect of influencing factors of the hydrolysis on the growth of S. thermophilus was investigated. Grass Carp fish skin was hydrolysed to peptides by enzymatic hydrolysis using protease ProteAX, and for the S. thermophilus growth, the optimal enzymatic hydrolysis conditions were temperature of 60 °C, initial pH of 9.0, enzyme concentration of 10 g kg -1 , hydrolysis time of 80 min, and ratio of material to liquid of 1:2. The Grass Carp fish skin hydrolysate (GCFSH) prepared under the optimum conditions was fractionated to five fragments (GCFSH 1, GCFSH 2, GCFSH 3, GCFSH 4, GCFSH 5) according to molecular weight sizes, in which the fragments GCFSH 4 and GCFSH 5, with molecular weights of less than 1000 Da, significantly promoted the growth of S. thermophilus. The hydrolysis process of Grass Carp fish skin can be simplified, and the peptides with molecular weights below 1000 Da in the hydrolysates are the best nitrogen source for proliferation of S. thermophilus. This work can provide a fundamental theoretical basis for the production of multi-component functional foods, especially in milk drinks or yogurt. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Transformations of the chemical compositions of high molecular weight DOM along a salinity transect: Using two dimensional correlation spectroscopy and principal component analysis approaches

NASA Astrophysics Data System (ADS)

Abdulla, Hussain A. N.; Minor, Elizabeth C.; Dias, Robert F.; Hatcher, Patrick G.

2013-10-01

In a study of chemical transformations of estuarine high-molecular-weight (HMW, >1000 Da) dissolved organic matter (DOM) collected over a period of two years along a transect through the Elizabeth River/Chesapeake Bay system to the coastal Atlantic Ocean off Virginia, USA, δ13C values, N/C ratios, and principal component analysis (PCA) of the solid-state 13C NMR (nuclear magnetic resonance) spectra of HMW-DOM show an abrupt change in both its sources and chemical structural composition occurring around salinity 20. HMW-DOM in the lower salinity region had lighter isotopic values, higher aromatic and lower carbohydrate contents relative to that in the higher salinity region. These changes around a salinity of 20 are possibly due to introduction of a significant amount of new carbon (autotrophic DOM) to the transect. PC-1 loadings plot shows that spatially differing DOM components are similar to previously reported 13C NMR spectra of heteropolysaccharides (HPS) and carboxyl-rich alicyclic molecules (CRAM). Applying two dimensional correlation spectroscopy techniques to 1H NMR spectra from the same samples reveals increases in the contribution of N-acetyl amino sugars, 6-deoxy sugars, and sulfated polysaccharides to HPS components along the salinity transect, which suggests a transition from plant derived carbohydrates to marine produced carbohydrates within the HMW-DOM pool. In contrast to what has been suggested previously, our combined results from 13C NMR, 1H NMR, and FTIR indicate that CRAM consists of at least two different classes of compounds (aliphatic polycarboxyl compounds and lignin-like compounds).

THE MITOTIC APPARATUS

PubMed Central

Stephens, R. E.

1967-01-01

The major 22S protein of the hexylene glycol-isolated mitotic apparatus has been characterized from spindle isolates and extracts of whole eggs and acetone powders of eggs from the sea urchins Strongylocentrotus purpuratus, Strongylocentrotus droebachiensis, and Arbacia punctulata. The protein is free of nucleotide, lipid, and ATPase activity. Essentially identical in amino acid composition, proteins from these species show a relatively high content of glutamic and aspartic acids and are fairly rich in hydrophobic amino acids. Optical rotatory dispersion studies indicate a helical content of about 20%, a value consistent with the proline content of the protein. The purified proteins have sedimentation rates in the range of 22–24S, diffusion constants of 2.4–2.5F, intrinsic viscosities of 3.7–4.3 ml/g, a partial specific volume of 0.74, and an average molecular weight of 880,000. Electron microscopy indicates a globular molecule with dimensions of approximately 150 by 200 A; such size and symmetry are consistent with hydrodynamic measurements. The 22S protein yields 6–7S, 9–10S, and 13–14S subunits below pH 4 or above pH 11. The 13–14S component has an estimated molecular weight of 600,000–700,000. A 5–6S particle is formed in 8 M urea or 5 M guanidine hydrochloride, while at pH 12 the 6–7S subunit is seen; each particle has a molecular weight of 230,000–240,000. In 8 M urea plus 2% mercaptoethanol or at pH 13, the molecular weight becomes 105,000–120,000; under these conditions the particle sediments at 2.5–3S and 4S, respectively. On the basis of these molecular weights, the 6–7S, 9–10S, 13–14S, and the parent 22S particle should be dimer, tetramer, hexamer, and octamer, respectively, of the 105,000–120,000 molecular weight subunit. The various subunits will reform the 22S particle when returned to neutral buffer, with the exception of the mercaptoethanol-treated urea subunit where breakage of disulfide bonds results in a polydisperse aggregate. The 22S particle itself is not susceptible to sulfhydryl reagents, implying either that the disulfide bonds are inaccessible or that they are unnecessary for maintenance of tertiary structure once the 22S particle has formed from subunits. PMID:10976220

Use of molecular modeling to determine the interaction and competition of gases within coal for carbon dioxide sequestration

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

Jeffrey D. Evanseck; Jeffry D. Madura; Jonathan P. Mathews

2006-04-21

Molecular modeling was employed to both visualize and probe our understanding of carbon dioxide sequestration within a bituminous coal. A large-scale (>20,000 atoms) 3D molecular representation of Pocahontas No. 3 coal was generated. This model was constructed based on a the review data of Stock and Muntean, oxidation and decarboxylation data for aromatic clustersize frequency of Stock and Obeng, and the combination of Laser Desorption Mass Spectrometry data with HRTEM, enabled the inclusion of a molecular weight distribution. The model contains 21,931 atoms, with a molecular mass of 174,873 amu, and an average molecular weight of 714 amu, with 201more » structural components. The structure was evaluated based on several characteristics to ensure a reasonable constitution (chemical and physical representation). The helium density of Pocahontas No. 3 coal is 1.34 g/cm{sup 3} (dmmf) and the model was 1.27 g/cm{sup 3}. The structure is microporous, with a pore volume comprising 34% of the volume as expected for a coal of this rank. The representation was used to visualize CO{sub 2}, and CH{sub 4} capacity, and the role of moisture in swelling and CO{sub 2}, and CH{sub 4} capacity reduction. Inclusion of 0.68% moisture by mass (ash-free) enabled the model to swell by 1.2% (volume). Inclusion of CO{sub 2} enabled volumetric swelling of 4%.« less

Molecular evidence of heavy-oil weathering following the M/V Cosco Busan spill: insights from Fourier transform ion cyclotron resonance mass spectrometry.

PubMed

Lemkau, Karin L; McKenna, Amy M; Podgorski, David C; Rodgers, Ryan P; Reddy, Christopher M

2014-04-01

Recent studies have highlighted a critical need to investigate oil weathering beyond the analytical window afforded by conventional gas chromatography (GC). In particular, techniques capable of detecting polar and higher molecular weight (HMW; > 400 Da) components abundant in crude and heavy fuel oils (HFOs) as well as transformation products. Here, we used atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (APPI FT-ICR MS) to identify molecular transformations in oil-residue samples from the 2007 M/V Cosco Busan HFO spill (San Francisco, CA). Over 617 days, the abundance and diversity of oxygen-containing compounds increased relative to the parent HFO, likely from bio- and photodegradation. HMW, highly aromatic, alkylated compounds decreased in relative abundance concurrent with increased relative abundance of less alkylated stable aromatic structures. Combining these results with GC-based data yielded a more comprehensive understanding of oil spill weathering. For example, dealkylation trends and the overall loss of HMW species observed by FT-ICR MS has not previously been documented and is counterintuitive given losses of lower molecular weight species observed by GC. These results suggest a region of relative stability at the interface of these techniques, which provides new indicators for studying long-term weathering and identifying sources.

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

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

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

2009-08-26

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

Gel filtration applied to the study of lipases and other esterases

PubMed Central

Downey, W. K.; Andrews, P.

1965-01-01

1. Sephadex G-100 and G-200 gel-filtration columns were calibrated for molecular-weight estimation with proteins of known molecular weights, and used to study the composition of several lipase or esterase preparations. 2. Enzymes from cow's milk, rat adipose tissue and pig pancreas were detected in the column effluents by their ability to liberate free acid from emulsified tributyrin at pH 8·5. 3. Four tributyrinases were detected in preparations from individual cow's milks. Molecular weights 62000, 75000 and 112000 were estimated for three of them, but although the fourth may be of unusually low molecular weight an estimate was not possible. 4. Extracts of rat adipose tissue apparently contained six tributyrinases (molecular weights 39000, 47000, 55000, 68000, 75000 and 200000) but the relative amounts of these enzymes varied widely from rat to rat. 5. Tributyrinase activity in juice expressed from pig pancreatic tissue was due mainly to one enzyme (molecular weight 42000). On the other hand, activity in extracts of acetone-dried pancreas was confined to material of molecular weight > 106, which may be an aggregated form of the lower-molecular-weight enzyme. 6. Activity in fractionated wheat-germ extracts was assayed with emulsified triacetin substrate, and was evidently due to one enzyme (molecular weight 51000). 7. Some problems arising in the application of gel filtration to the study of lipase–esterase systems were indicated. PMID:14340054

Immunostimulative Activity of Low Molecular Weight Chitosans in RAW264.7 Macrophages

PubMed Central

Wu, Ning; Wen, Zheng-Shun; Xiang, Xing-Wei; Huang, Yan-Na; Gao, Yang; Qu, You-Le

2015-01-01

Chitosan and its derivatives such as low molecular weight chitosans (LMWCs) have been reported to exert many biological activities, such as antioxidant and antitumor effects. However, complex and molecular weight dependent effects of chitosan remain controversial and the mechanisms that mediate these complex effects are still poorly defined. This study was carried out to investigate the immunostimulative effect of different molecular weight chitosan in RAW264.7 macrophages. Our data suggested that two LMWCs (molecular weight of 3 kDa and 50 kDa) both possessed immunostimulative activity, which was dependent on dose and, at the higher doses, also on the molecular weight. LMWCs could significantly enhance the the pinocytic activity, and induce the production of tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), interferon-γ (IFN-γ), nitric oxide (NO) and inducible nitric oxide synthase (iNOS) in a molecular weight and concentration-dependent manner. LMWCs were further showed to promote the expression of the genes including iNOS, TNF-α. Taken together, our findings suggested that LMWCs elicited significantly immunomodulatory response through up-regulating mRNA expression of proinflammatory cytokines and activated RAW264.7 macrophage in a molecular weight- and concentration-dependent manner. PMID:26437419

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.

PubMed

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 .

Effects of Molecular Weight upon Irradiation-Cross-Linked Poly(vinyl alcohol)/Clay Aerogel Properties.

PubMed

Chen, Hong-Bing; Zhao, Yan; Shen, Peng; Wang, Jun-Sheng; Huang, Wei; Schiraldi, David A

2015-09-16

Facile fabrication of mechanically strong poly(vinyl alcohol) (PVOH)/clay aerogel composites through a combination of increasing polymer molecular weights and gamma irradiation-cross-linking is reported herein. The aerogels produced from high polymer molecular weights exhibit significantly increased compressive moduli, similar to the effect of irradiation-induced cross-linking. The required irradiation dose for fabricating strong PVOH composite aerogels with dense microstructure decreased with increasing polymer molecular weight. Neither thermal stability nor flammability was significantly changed by altering the polymer molecular weight or by modest gamma irradiation, but they were highly dependent upon the polymer/clay ratio in the aerogel. Optimization of the mechanical, thermal, and flammability properties of these composite aerogels could therefore be obtained by using relatively low levels of polymer, with very high polymer molecular weight, or lower molecular weight coupled with moderate gamma irradiation. The facile preparation of strong, low flammability aerogels is an alternative to traditional polymer foams in applications where fire safety is important.

High resolution mass spectrometry method and system for analysis of whole proteins and other large molecules

DOEpatents

Reilly, Peter T. A. [Knoxville, TN; Harris, William A [Naperville, IL

2010-03-02

A matrix assisted laser desorption/ionization (MALDI) method and related system for analyzing high molecular weight analytes includes the steps of providing at least one matrix-containing particle inside an ion trap, wherein at least one high molecular weight analyte molecule is provided within the matrix-containing particle, and MALDI on the high molecular weight particle while within the ion trap. A laser power used for ionization is sufficient to completely vaporize the particle and form at least one high molecular weight analyte ion, but is low enough to avoid fragmenting the high molecular weight analyte ion. The high molecular weight analyte ion is extracted out from the ion trap, and is then analyzed using a detector. The detector is preferably a pyrolyzing and ionizing detector.

Process for crosslinking and extending conjugated diene-containing polymers

NASA Technical Reports Server (NTRS)

Bell, Vernon L. (Inventor); Havens, Stephen J. (Inventor)

1977-01-01

A process using a Diels-Alder reaction which increases the molecular weight and/or crosslinks polymers by reacting the polymers with bisunsaturated dienophiles is developed. The polymer comprises at least 75% by weight based on the reaction product, has a molecular weight of at least 5000 and a plurality of conjugated 1,3-diene systems incorporated into the molecular structure. A dienophile reaction with the conjugated 1,3-diene of the polymer is at least 1% by weight based on the reaction product. Examples of the polymer include polyesters, polyamides, polyethers, polysulfones and copolymers. The bisunsaturated dienophiles may include bis-maleimides, bis maleic and bis tumaric esters and amides. This method for expanding the molecular weight chains of the polymers, preferable thermoplastics, is advantageous for processing or fabricating thermoplastics. A low molecular weight thermoplastic is converted to a high molecular weight plastic having improved strength and toughness for use in the completed end use article.

Opposing effects of low molecular weight heparins on the release of inflammatory cytokines from peripheral blood mononuclear cells of asthmatics.

PubMed

Shastri, Madhur D; Stewart, Niall; Eapen, Mathew; Peterson, Gregory M; Zaidi, Syed Tabish R; Gueven, Nuri; Sohal, Sukhwinder Singh; Patel, Rahul P

2015-01-01

T-cell-mediated inflammatory cytokines, such as interleukin (IL)-4, IL-5, IL-13 and tumor necrosis factor-alpha (TNF-α), play an important role in the initiation and progression of inflammatory airways diseases. Low-molecular-weight heparins (LMWHs), widely used anticoagulants, possess anti-inflammatory properties making them potential treatment options for inflammatory diseases, including asthma. In the current study, we investigated the modulating effects of two LMWHs (enoxaparin and dalteparin) on the release of cytokines from stimulated peripheral blood mononuclear cells (PBMCs) of asthmatic subjects to identify the specific components responsible for the effects. PBMCs from asthmatic subjects (consist of ~75% of T-cells) were isolated from blood taken from ten asthmatic subjects. The PBMCs were pre-treated in the presence or absence of different concentrations of LMWHs, and were then stimulated by phytohaemagglutinin for the release of IL-4, IL-5, IL-13 and TNF-α. LMWHs were completely or selectively desulfated and their anticoagulant effect, as well as the ability to modulate cytokine release, was determined. LMWHs were chromatographically fractionated and each fraction was tested for molecular weight determination along with an assessment of anticoagulant potency and effect on cytokine release. Enoxaparin inhibited cytokine release by more than 48%, whereas dalteparin increased their release by more than 25%. The observed anti-inflammatory effects of enoxaparin were independent of their anticoagulant activities. Smaller fractions, in particular dp4 (four saccharide units), were responsible for the inhibitory effect of enoxaparin. Whereas, the larger fractions, in particular dp22 (twenty two saccharide units), were associated with the stimulatory effect of dalteparin. Enoxaparin and dalteparin demonstrated opposing effects on inflammatory markers. These observed effects could be due to the presence of structurally different components in the two LMWHs arising from different methods of depolymerisation. This study provides a platform for further studies investigating the usefulness of enoxaparin in various inflammatory diseases.

Carbon Nanotube Based Molecular Electronics and Motors: A View from Classical and Quantum Dynamics Simulations

NASA Technical Reports Server (NTRS)

Srivastava, Deepak; Saini, Subhash (Technical Monitor)

1998-01-01

The tubular forms of fullerenes popularly known as carbon nanotubes are experimentally produced as single-, multiwall, and rope configurations. The nanotubes and nanoropes have shown to exhibit unusual mechanical and electronic properties. The single wall nanotubes exhibit both semiconducting and metallic behavior. In short undefected lengths they are the known strongest fibers which are unbreakable even when bent in half. Grown in ropes their tensile strength is approximately 100 times greater than steel at only one sixth the weight. Employing large scale classical and quantum molecular dynamics simulations we will explore the use of carbon nanotubes and carbon nanotube junctions in 2-, 3-, and 4-point molecular electronic device components, dynamic strength characterization for compressive, bending and torsional strains, and chemical functionalization for possible use in a nanoscale molecular motor. The above is an unclassified material produced for non-competitive basic research in the nanotechnology area.

Production of high molecular weight polylactic acid

DOEpatents

Bonsignore, Patrick V.

1995-01-01

A degradable high molecular weight poly(lactic acid). A 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.

Mechanisms of plastic deformation in highly cross-linked UHMWPE for total hip components--the molecular physics viewpoint.

PubMed

Takahashi, Yasuhito; Shishido, Takaaki; Yamamoto, Kengo; Masaoka, Toshinori; Kubo, Kosuke; Tateiwa, Toshiyuki; Pezzotti, Giuseppe

2015-02-01

Plastic deformation is an unavoidable event in biomedical polymeric implants for load-bearing application during long-term in-vivo service life, which involves a mass transfer process, irreversible chain motion, and molecular reorganization. Deformation-induced microstructural alterations greatly affect mechanical properties and durability of implant devices. The present research focused on evaluating, from a molecular physics viewpoint, the impact of externally applied strain (or stress) in ultra-high molecular weight polyethylene (UHMWPE) prostheses, subjected to radiation cross-linking and subsequent remelting for application in total hip arthroplasty (THA). Two different types of commercial acetabular liners, which belong to the first-generation highly cross-linked UHMWPE (HXLPE), were investigated by means of confocal/polarized Raman microprobe spectroscopy. The amount of crystalline region and the spatial distribution of molecular chain orientation were quantitatively analyzed according to a combined theory including Raman selection rules for the polyethylene orthorhombic structure and the orientation distribution function (ODF) statistical approach. The structurally important finding was that pronounced recrystallization and molecular reorientation increasingly appeared in the near-surface regions of HXLPE liners with increasing the amount of plastic (compressive) deformation stored in the microstructure. Such molecular rearrangements, occurred in response to external strains, locally increase surface cross-shear (CS) stresses, which in turn trigger microscopic wear processes in HXLPE acetabular liners. Thus, on the basis of the results obtained at the molecular scale, we emphasize here the importance of minimizing the development of irrecoverable deformation strain in order to retain the pristine and intrinsically high wear performance of HXLPE components. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of the Addition of a Labile Gelatin Component on the Degradation and Solute Release Kinetics of a Stable PEG Hydrogel

PubMed Central

Waldeck, H.; Kao, W. J.

2013-01-01

Characterization of the degradation mechanisms and resulting products of biodegradable materials is critical in understanding the behavior of the material including solute transport and biological response. Previous mathematical analyses of a semi-interpenetrating network (sIPN) containing both labile gelatin and a stable cross-linked poly(ethylene glycol) (PEG) network found that diffusion-based models alone were unable to explain the release kinetics of solutes from the system. In this study, degradation of the sIPN and its effect on solute release and swelling kinetics were investigated. The kinetics of the primary mode of degradation, gelatin dissolution, was dependent on temperature, preparation methods, PEGdA and gelatin concentration, and the weight ratio between the gelatin and PEG. The gelatin dissolution rate positively correlated with both matrix swelling and the release kinetics of high-molecular-weight model compound, FITC-dextran. Coupled with previous in vitro studies, the kinetics of sIPN degradation provided insights into the time-dependent changes in cellular response including adhesion and protein expression. These results provide a facile guide in material formulation to control the delivery of high-molecular-weight compounds with concomitant modulation of cellular behavior. PMID:21801489

Low molecular weight components of polymers used in packaging.

PubMed Central

Gilbert, S G

1975-01-01

The increasing use of polymers in packaging of foods and drugs focuses attention on the possible chronic toxicity relations of migrants from these polymers to the contents. Such migrants can arise from residues and additives in the polymers from manufacturing processes used in fabrication of packages. The origin and chemical nature of potential migrants, the methods of transfer, and principles involved in development of safety criteria for their regulation are discussed. PMID:1236793

Molecular Weight of Deoxyribonucleic Acid Synthesized During Initiation of Chromosome Replication in Escherichia coli

PubMed Central

Kuempel, Peter L.

1972-01-01

Alkaline sucrose gradients were used to study the molecular weight of deoxyribonucleic acid (DNA) synthesized during the initiation of chromosome replication in Escherichia coli 15 TAU-bar. The experiments were conducted to determine whether newly synthesized, replication origin DNA is attached to higher-molecular-weight parental DNA. Little of the DNA synthesized after readdition of required amino acids to cells previously deprived of the amino acids was present in DNA with a molecular weight comparable to that of the parental DNA. The newly synthesized, low-molecular-weight DNA rapidly appeared in higher-molecular-weight material, but there was an upper limit to the size of this intermediate-molecular-weight DNA. This limit was not observed when exponentially growing cells converted newly synthesized DNA to higher-molecular-weight material. The size of the intermediate-molecular-weight DNA was related to the age of the replication forks, and the size increased as the replication forks moved further from the replication origin. The results indicate that the newly synthesized replication origin DNA is not attached to parental DNA, but it is rapidly attached to the growing strands that extend from the replication fork to the replication origin, or to the other replication fork if replication is bidirectional. Experiments are reported which demonstrate that the DNA investigated was from the vicinity of the replication origin and was not plasmid DNA or DNA from random positions on the chromosome. PMID:4562387

Molecular forms of C-type natriuretic peptide in cerebrospinal fluid and plasma reflect differential processing in brain and pituitary tissues.

PubMed

Wilson, Michele O; Barrell, Graham K; Prickett, Timothy C R; Espiner, Eric A

2018-01-01

C-type natriuretic peptide (CNP) is a paracrine growth factor widely expressed within tissues of the central nervous system. Consistent with this is the high concentration of CNP in cerebrospinal fluid (CSF), exceeding levels in the systemic circulation. CNP abundance is high in hypothalamus and especially enriched in pituitary tissue where - in contrast to hypothalamus - processing to CNP-22 is minimal. Recently we have shown that dexamethasone acutely raises CNP peptides throughout the brain as well as in CSF and plasma. Postulating that molecular forms of CNP would differ in central tissues compared to forms in pituitary and plasma, we have characterized the molecular forms of CNP in tissues (hypothalamus, anterior and posterior pituitary gland) and associated fluids (CSF and plasma) using size-exclusion high performance liquid chromatography (SE-HPLC) and radioimmunoassay in control (saline-treated) and dexamethasone-treated adult sheep. Three immunoreactive-CNP components were identified which were consistent with proCNP (1-103), CNP-53 and CNP-22, but the presence and proportions of these different fragments differed among tissues. Peaks consistent with CNP-53 were the dominant form in all tissues and fluids. Peaks consistent with proCNP, conspicuous in hypothalamic extracts, were negligible in CSF whereas proportions of low molecular weight immunoreactivity (IR) consistent with CNP-22 were similar in hypothalamus, posterior pituitary gland and CSF. In contrast, in both plasma and the anterior pituitary gland, proportions of higher molecular weight IR, consistent with CNP-53 and proCNP, predominated, and low molecular weight IR consistent with CNP-22 was very low. After dexamethasone, proCNP like material - but not other forms - was increased in all samples except CSF, consistent with increased synthesis and secretion. In conclusion, immunoreactive forms of CNP in central tissues differ from those identified in anterior pituitary tissue and plasma - suggesting that the anterior pituitary gland may contribute to systemic levels of CNP in some physiological settings. Copyright © 2017 Elsevier Inc. All rights reserved.

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

USGS Publications Warehouse

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.

Identification of polypeptides necessary for chemotaxis in Escherichia coli.

PubMed Central

Silverman, M; Simon, M

1977-01-01

Molecular cloning techniques were used to construct Escherichia coli-lambda hybrids that contained many of the genes necessary for flagellar rotation and chemotaxis. The properties of specific hybrids that carried the classical "cheA" and "cheB" loci were examined by genetic complementation and by measuring the capacity of the hybrids to direct the synthesis of specific polypeptides. The results of these tests with lambda hybrids and with a series of deletion mutations derived from the hybrids redefined the "cheA" and "cheB" regions. Six genes were resolved: cheA, cheW, cheX, cheB, cheY, and cheZ. They directed the synthesis of specific polypeptides with the following apparent molecular weights: cheA, 76,000 and 66,000; cheW, 12,000; cheX, 28,000; cheB, 38,000; cheY, 8,000; and cheZ, 24,000. The presence of another gene, cheM, was inferred from the protein synthesis experiments. The cheM gene directed the synthesis of polypeptides with apparent molecular weights of 63,000, 61,000, and 60,000. The synthesis of all of these polypeptides is regulated by the same mechanisms that regulate the synthesis of flagellar-related structural components. Images PMID:324984

Mechlorethamine-based drug structures for intervention of central nervous system tumors.

PubMed

Bartzatt, Ronald

2013-06-01

Tumors of the central nervous system are the third most common type of childhood cancers. Brain tumors occur in children and adults; however pediatric patients require a different treatment process. Thirteen drugs similar to mechlorethamine are analyzed in this study. These drugs possess molecular properties enabling substantial and successful access to tumors of the central nervous system. All drugs exhibit zero violations of the Rule of 5, which indicate favorable bioavailability. Ranges in Log P, formula weight, and polar surface area for these drugs are: 1.554 to 3.52, 156.06 to 460.45, and 3.238 Angstroms(2) to 45.471 Angstroms(2), respectively. Hierarchical cluster analysis determined that agents 7 and 12 are most similar to the parent compound mechlorethamine. The mean values of Log P, formula weight, polar surface area, and molecular volume are 2.25, 268.51, 16.57 Angstroms(2), and 227.01 Angstroms(3), respectively. Principal component analysis indicates that agents 7 and 12 are most similar to mechlorethamine and multiple regression analysis of molecular properties produced a model to enable the design of similar alkylating agents. Values of Log (Cbrain/Cblood) indicate these agents will have very high permeation into the central nervous system.

Mixed refrigerant cycle with neon, hydrogen, and helium for cooling sc power transmission lines

NASA Astrophysics Data System (ADS)

Kloeppel, S.; Dittmar, N.; Haberstroh, Ch; Quack, H.

2017-02-01

The use of superconductors in very long power transmission lines requires a reliable and effective cooling. Since the use of cryocoolers does not appear feasible for very long distances, a cryogenic refrigeration cycle needs to be developed. For cooling superconducting cables based on MgB2 (T c = 39 K), liquid hydrogen (LH2) is the obvious cooling agent. For recooling LH2, one would need a refrigeration cycle providing temperatures at around 20 K. For this purpose, one could propose the use of a helium refrigeration cycle. But the very low molecular weight of helium restricts the use of turbo compressors, which limits the overall efficiency. In order to increase the molecular weight of the refrigerant a mixture of cryogens could be used, allowing the use of a turbo compressor. Temperatures below the triple point of neon are achieved by phase separation. This paper presents a possible layout of a refrigeration cycle utilizing a three component mixture of neon, hydrogen, and helium.

The numerical simulation on swelling factor and extraction rate of a tight crude oil and SC-CO2 system

NASA Astrophysics Data System (ADS)

Zou, Hongjun; Gong, Houjian; Li, Yajun; Dong, Mingzhe

2018-03-01

A method was established to study swelling and extraction between CO2 and crude oil, and the influences of pressure, temperature and molecular weight were investigated. Firstly, laboratory analysis was conducted to determine the pseudo-component and other parameters of the crude oil. Then swelling and extraction of the crude oil and SC-CO2 system were calculated by computer simulation. The results show that the pressure and temperature have little influence on the swelling and extraction between CO2 and crude oil when the mole fraction of CO2 is lower. A higher pressure and temperature is more beneficial to the interaction of CO2 and crude oil, while the swelling and extraction will not be obvious when the system is miscible. And the smaller the molecular weight of the oil is, the larger the maximum value of the swelling factor of CO2 and crude oil changes. The study of swelling and extraction plays an important role in the oilfield stimulation.

Effect of Injection Molding Melt Temperatures on PLGA Craniofacial Plate Properties during In Vitro Degradation

PubMed Central

Fancello, Eduardo Alberto

2017-01-01

The purpose of this article is to present mechanical and physicochemical properties during in vitro degradation of PLGA material as craniofacial plates based on different values of injection molded temperatures. Injection molded plates were submitted to in vitro degradation in a thermostat bath at 37 ± 1°C by 16 weeks. The material was removed after 15, 30, 60, and 120 days; then bending stiffness, crystallinity, molecular weights, and viscoelasticity were studied. A significant decrease of molecular weight and mechanical properties over time and a difference in FT-IR after 60 days showed faster degradation of the material in the geometry studied. DSC analysis confirmed that the crystallization occurred, especially in higher melt temperature condition. DMA analysis suggests a greater contribution of the viscous component of higher temperature than lower temperature in thermomechanical behavior. The results suggest that physical-mechanical properties of PLGA plates among degradation differ per injection molding temperatures. PMID:29056968

Authentication of animal origin of heparin and low molecular weight heparin including ovine, porcine and bovine species using 1D NMR spectroscopy and chemometric tools.

PubMed

Monakhova, Yulia B; Diehl, Bernd W K; Fareed, Jawed

2018-02-05

High resolution (600MHz) nuclear magnetic resonance (NMR) spectroscopy is used to distinguish heparin and low-molecular weight heparins (LMWHs) produced from porcine, bovine and ovine mucosal tissues as well as their blends. For multivariate analysis several statistical methods such as principal component analysis (PCA), factor discriminant analysis (FDA), partial least squares - discriminant analysis (PLS-DA), linear discriminant analysis (LDA) were utilized for the modeling of NMR data of more than 100 authentic samples. Heparin and LMWH samples from the independent test set (n=15) were 100% correctly classified according to its animal origin. Moreover, by using 1 H NMR coupled with chemometrics and several batches of bovine heparins from two producers were differentiated. Thus, NMR spectroscopy combined with chemometrics is an efficient tool for simultaneous identification of animal origin and process based manufacturing difference in heparin products. Copyright © 2017 Elsevier B.V. All rights reserved.

[Effects of low molecular weight organic acids on redox reactions of mercury].

PubMed

Zhao, Shi-Bo; Sun, Rong-Guo; Wang, Ding-Yong; Wang, Xiao-Wen; Zhang, Cheng

2014-06-01

To study the effects of the main component of vegetation root exudates-low molecular weight organic acids on the redox reactions of mercury, laboratory experiments were conducted to investigate the roles of tartaric, citric, and succinic acid in the redox reactions of mercury, and to analyze their interaction mechanism. The results indicated that tartaric acid significantly stimulated the mercury reduction reaction, while citric acid had inhibitory effect. Succinic acid improved the reduction rate at low concentration, and inhibited the reaction at high concentration. The mercury reduction rate by tartaric acid treatment was second-order with respect to Hg2+ concentration, ranging from 0.0014 L x (ng x min)(-1) to 0.005 6 L x (ng x min)(-1). All three organic acids showed a capacity for oxidating Hg(0) in the early stage, but the oxidized Hg(0) was subsequently reduced. The oxidation capacity of the three organic acids was in the order of citric acid > tartaric acid > succinic acid.

Production of high molecular weight polylactic acid

DOEpatents

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.

Effect of molecular weight profile of sorghum proanthocyanidins on resistant starch formation.

PubMed

Barros, Frederico; Awika, Joseph; Rooney, Lloyd W

2014-04-01

There is a growing interest to increase resistant starch (RS) in foods through natural modification of starch. Sorghum tannins (proanthocyanidins, PAs) were recently reported to interact with starch, increasing RS. However, there is no information about how the molecular weight profile of PAs affects RS formation. This study investigated how different-molecular-weight PAs from sorghum affected RS formation in different starch models. The levels of RS were higher (331-437 mg g(-1)) when high-amylose starch was cooked with phenolic extracts containing mostly high-molecular-weight PAs compared with extracts containing lower-molecular-weight PAs or monomeric catechin (249-285 mg g(-1)). In general, binding capacity of PAs with amylose increased proportionally with molecular weight. For example, the percentage of PAs bound to amylose increased from 45% (PAs with degree of polymerization (DP) = 6) to 94% (polymeric PAs, DP > 10). The results demonstrate that molecular weight of the PAs directly affects their interaction with starch: the higher the molecular weight, the stronger the binding to amylose and the higher the RS formation. Polymeric PAs from sorghum can naturally modify starch by interacting strongly with amylose and are thus most suitable to produce foods with higher RS. © 2013 Society of Chemical Industry.

Characterization of organic matter in cloud waters sampled at the puy de Dôme mountain using FT-ICR-MS

NASA Astrophysics Data System (ADS)

Bianco, A.; Chaumerliac, N.; Vaitilingom, M.; Deguillaume, L.; Bridoux, M. C.

2017-12-01

The chemical composition of organic matter in cloud water is highly complex. The organic species result from their dissolution from the gas phase or from the soluble fraction of the particle phase. They are also produced by aqueous phase reactivity. Several low molecular weight organic species have been quantified such as aldehydes and carboxylic acids. Recently, amino acids were also detected in cloud water and their presence is related to the presence of microorganisms. Compounds presenting similarities with high molecular weight organic substances or HULIS found in aerosols were also observed in clouds. Overall, these studies mainly focused on individual compounds or functional groups rather than the complex mixture at the molecular level. This study presents a non-targeted approach to characterize the organic matter in clouds. Samples were collected at the puy de Dôme Mountain (France). Two cloud water samples (June & July 2016) were analyzed using high resolution mass spectrometry (ESI-FT-ICR-MS 9.4T). A reversed solid phase extraction (SPE) procedure was performed to concentrate dissolved organic matter components. Composer (v.1.5.3) software was used to filter the mass spectral data, recalibrate externally the dataset and calculate all possible formulas for detected anions. The first cloud sample (June) resulted from air mass coming from the North (North Sea) while the second one (July) resulted from air mass coming from the West (Atlantic Ocean). Thus, both cloud events derived from marine air masses but were characterized by different hydrogen peroxide concentration and dissolved organic carbon content and were sampled at different periods during the day. Elemental compositions of 6487 and 3284 unique molecular species were identified in each sample. Nitrogen-containing compounds (CHNO compounds), sulfur-containing compounds (CHOS & CHNOS compounds) and other oxygen-containing compounds (CHO compounds) with molecular weights up to 800 Da were detected. The main class is CHNO (53% for both samples) while sulfur-containing compounds represent for the two samples respectively 21 & 14% of the total assigned molecular formulas. CHO compounds molecular formulas are respectively 25 & 32%. Among the two samples, only 2490 molecular formulas were found common to the two samples.

Chromatographic molecular weight measurements for heparin, its fragments and fractions, and other glycosaminoglycans.

PubMed

Mulloy, Barbara; Hogwood, John

2015-01-01

Glycosaminoglycan samples are usually polydisperse, consisting of molecules with differing length and differing sequence. Methods for measuring the molecular weight of heparin have been developed to assure the quality and consistency of heparin products for medicinal use, and these methods can be applied in other laboratory contexts. In the method described here, high-performance gel permeation chromatography is calibrated using appropriate heparin molecular weight markers or a single broad standard calibrant, and used to characterize the molecular weight distribution of polydisperse samples or the peak molecular weight of monodisperse, or approximately monodisperse, heparin fractions. The same technology can be adapted for use with other glycosaminoglycans.

Proteolytic fragmentation and peptide mapping of human carboxyamidomethylated tracheobronchial mucin.

PubMed

Rose, M C; Kaufman, B; Martin, B M

1989-05-15

Human tracheobronchial mucin was isolated from lung mucosal gel by chromatography on Sepharose 4B in the presence of dissociating and reducing agents, and its thiol residues were carboxyamidomethylated with iodo[1(-14)C]acetamide. The 14C-carboxyamido-methylated mucin was purified by chromatography on Sepharose 2B. No low molecular weight components were detected by molecular sieve chromatography or polyacrylamide gel electrophoresis in the presence of dissociating and reducing agents or by analytical density centrifugation in CsCl/guanidinium chloride. After digestion of the purified 14C-mucin with trypsin-L-1-tosylamido-2-phenylethyl chloromethyl ketone, three fractions (TR-1, TR-2, and TR-3) were observed by chromatography on Sepharose 4B. TR-1, a 260-kDa mucin glycopeptide fragment, contained all of the neutral hexose and blood group activity and 20% of the radioactivity in the undigested mucin. TR-1 was refractory to a second incubation with trypsin but could be digested by papain or Pronase to a smaller mucin glycopeptide fraction, as judged by the slight decrease in apparent molecular weight on Sepharose CL-4B. These mucin glycopeptides contained approximately 50% of the radioactivity in the TR-1 fraction, indicating that the glycosylated domains of carboxyamidomethylated tracheobronchial mucin contained thiol residues. The remainder of the radioactivity from papain or Pronase digests of TR-1 eluted, like the TR-3 fractions, in the salt fraction on Sepharose CL-4B. Peptide mapping of the nonglycosylated TR-3 fraction by TLC and high voltage electrophoresis yielded six principal and several less intensely stained ninhydrin reactive components, with the radiolabel concentrated in one of the latter peptides. Peptide purification of the TR-3 fraction by high pressure liquid chromatography on a C18 reverse phase column demonstrated the presence of four major peptides, with TR-3A being the dominant component. The TR-3D peptide contained S-carboxy-aminomethylcysteine and had 69% sequence similarity to the sgs-7 salivary glue protein of Drosophila.

Effect of PEO molecular weight on the miscibility and dynamics in epoxy/PEO blends.

PubMed

Lu, Shoudong; Zhang, Rongchun; Wang, Xiaoliang; Sun, Pingchuan; Lv, Weifeng; Liu, Qingjie; Jia, Ninghong

2015-11-01

In this work, the effect of poly(ethylene oxide) (PEO) molecular weight in blends of epoxy (ER) and PEO on the miscibility, inter-chain weak interactions and local dynamics were systematically investigated by multi-frequency temperature modulation DSC and solid-state NMR techniques. We found that the molecular weight (M(w)) of PEO was a crucial factor in controlling the miscibility, chain dynamics and hydrogen bonding interactions between PEO and ER. A critical PEO molecular weight (M(crit)) around 4.5k was found. PEO was well miscible with ER when the molecular weight was below M(crit), where the chain motion of PEO was restricted due to strong inter-chain hydrogen bonding interactions. However, for the blends with high molecular weight PEO (M(w) > M(crit)), the miscibility between PEO and ER was poor, and most of PEO chains were considerably mobile. Finally, polarization inversion spin exchange at magic angle (PISEMA) solid-state NMR experiment further revealed the different mobility of the PEO in ER/PEO blends with different molecular weight of PEO at molecular level. Based on the DSC and NMR results, a tentative model was proposed to illustrate the miscibility in ER/PEO blends.

Enzymatic and acidic degradation of high molecular weight dextran into low molecular weight and its characterizations using novel Diffusion-ordered NMR spectroscopy.

PubMed

Iqbal, Samina; Marchetti, Roberta; Aman, Afsheen; Silipo, Alba; Qader, Shah Ali Ul; Molinaro, Antonio

2017-10-01

Low molecular weight fractions were derived from native high molecular weight dextran produced by Leuconostoc mesenteroides KIBGE-IB26. Structural characterization of native and low molecular weight fractions obtained after acidic and enzymatic hydrolysis was done using FTIR and NMR spectroscopy. The molecular weight was estimated using Diffusion Ordered NMR spectroscopy. Native dextran (892kDa) is composed of α-(1→6) glycosidic linkage along with α-(1→3) branching. Major proportion of 528kDa dextran was obtained after prolong enzymatic hydrolysis however, an effective acidic treatment at pH-1.4 up to 02 and 04h of exposure resulted in the formation of 77kDa and 57kDa, respectively. The increment in pH from 1.4 to 1.8 lowered the hydrolysis efficiency and resulted in the formation of 270kDa dextran fraction. The results suggest that derived low molecular weight water soluble fractions can be utilized as a drug delivery carrier along with multiple application relating pharmaceutical industries. Copyright © 2017 Elsevier B.V. All rights reserved.

Air-to-sea fluxes of lipids at enewetak atoll

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

Zafiriou, O.C.; Gagosian, R.B.; Peltzer, E.T.

1985-02-20

We report data for the Enewetak site of the SEAREX program from the rainy season in 1979. The concentrations of n-alkanes, n-alkanols, sterols, n-alkanoic acids and their salts, and total organic compounds in rain are reported, as well as the apparent gaseous hydrocarbon concentrations. These data and information on the particulate forms are analyzed in conjunction with ancillary chemical and meterological data to draw inferences about sources, fluxes, and chemical speciations. While the higher molecular weight lipid biomarker components are exclusively terrestrial, the organic carbon in rain may be derived from atmospheric transformations of terrestrial carbon. Distinctively marine components aremore » nearly absent. Comparison of the scavenging ratios of the organic components in rain vs. those for clays reveals that the alkanoic acids and the higher molecular weight alkanols behave as essentially particulate materials, whereas lower alkanols and most hydrocarbons show much higher scavenging ratios, probably due to the involvement of a gaseous phase or sampling artifact. Vaporization in the atmosphere and scaveging of a gas phase would lead to higher scaveging ratios; vaporization during sampling would give low aerosol concentrations and high gas-phase concentrations, leading to high scavening ratios. The major fluxes at Enewetak result from rain rather than dry deposition, and extrapolating the measured values to meaningful annual averages requires adjustment for seasonally varying source intensity and rain dynamics. Aerosol data for other seasons and other substances are used to correct for source-strength intensity variations, and a /sup 210/Pb/organic compound correlation is established and extrapolated to adjust for rainfall volume effects.« less

Distinguishing dissolved organic matter at its origin: size and optical properties of leaf-litter leachates.

PubMed

Cuss, C W; Guéguen, C

2013-09-01

Dissolved organic matter (DOM) was leached from eight distinct samples of leaves taken from six distinct trees (red maple, bur oak at three times of the year, two sugar maple and two white spruce trees from disparate soil types). Multiple samples were taken over 72-96h of leaching. The size and optical properties of leachates were assessed using asymmetrical flow field-flow fractionation (AF4) coupled to diode-array ultraviolet/visible absorbance and excitation-emission matrix fluorescence detectors (EEM). The fluorescence of unfractionated samples was also analyzed. EEMs were analyzed using parallel factor analysis (PARAFAC) and principal component analysis (PCA) of proportional component loadings. Both the unfractionated and AF4-fractionated leachates had distinct size and optical properties. The 95% confidence ranges for molecular weight distributions were determined as: 210-440Da for spruce, 540-920Da for sugar maple, 630-800Da for spring oak leaves, 930-950Da for senescent oak, 1490-1670 for senescent red maple, and 3430-4270Da for oak leaves that were collected from the ground after spring thaw. In most cases the fluorescence properties of leachates were different for individuals from different soil types and across seasons; however, PCA of PARAFAC loadings revealed that the observed distinctiveness was chiefly species-based. Strong correlations were found between the molecular weight distribution of both unfractionated and fractionated leachates and their principal component loadings (R(2)=0.85 and 0.95, respectively). It is concluded that results support a species-based origin for differences in optical properties. Copyright © 2013 Elsevier Ltd. All rights reserved.

Chemical composition and cycling of dissolved organic matter in the Mid-Atlantic Bight

NASA Astrophysics Data System (ADS)

Aluwihare, Lihini I.; Repeta, Daniel J.; Chen, Robert F.

This study focuses on the chemical characterization of high molecular-weight dissolved organic matter (HMW DOM) isolated from the Middle Atlantic Bight in April 1994 and March 1996. Using proton nuclear magnetic resonance spectroscopy ( 1HNMR) and monosaccharide analysis we compared both spatial and temporal variations in the chemical structure of HMW DOM across this region. Our analyses support the presence of at least two compositionally distinct components to HMW DOM. The major component is acyl polysaccharide (APS), a biopolymer rich in carbohydrates, acetate and lipid, accounting for between 50% and 80% of the total high molecular-weight dissolved organic carbon (HMW DOC) in surface samples. APS is most abundant in fully marine, surface-water samples, and is a product of autochthonous production. Organic matter with spectral properties characteristic of humic substances is the second major component of HMW DOM. Humic substances are most abundant (up to 49% of the total carbon) in samples collected from estuaries, near the coast, and in deep water, suggesting both marine and perhaps terrestrial sources. Radiocarbon analyses of neutral monosaccharides released by the hydrolysis of APS have similar and modern (average 71‰) Δ 14C values. Radiocarbon data support our suggestion that these sugars occur as part of a common macromolecule, with an origin via recent biosynthesis. Preliminary radiocarbon data for total neutral monosaccharides isolated from APS at 300 and 750 m show this fraction to be substantially enriched relative to total HMW DOC and DOC. The relatively enriched radiocarbon values of APS at depth suggest APS is rapidly transported into the deep ocean.

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.

PubMed

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.

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

PubMed

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.

21 CFR 172.820 - Polyethylene glycol (mean molecular weight 200-9,500).

Code of Federal Regulations, 2010 CFR

2010-04-01

... ethylene oxide and water with a mean molecular weight of 200 to 9,500. (2) It contains no more than 0.2 percent total by weight of ethylene and diethylene glycols when tested by the analytical methods... the total ethylene and diethylene glycol content of polyethylene glycols having mean molecular weights...

In vivo anti-radiation activities of the Ulva pertusa polysaccharides and polysaccharide-iron(III) complex.

PubMed

Shi, Jinming; Cheng, Cuilin; Zhao, Haitian; Jing, Jing; Gong, Ning; Lu, Weihong

2013-09-01

Polysaccharides with different molecular weights were extracted from Ulva pertusa and fractionated by ultrafiltration. Iron(III) complex of the low molecular-weight U. pertusa polysaccharides were synthesized. Atomic absorption spectrum showed that the iron content of iron(III)-polysaccharide complex was 27.4%. The comparison between U. pertusa polysaccharides and their iron(III) complex showed that iron chelating altered the structural characteristics of the polysaccharides. The bioactivity analysis showed that polysaccharide with low molecular weight was more effective than polysaccharide with high molecular weight in protecting mice from radiation induced damages on bone marrow cells and immune system. Results also proved that the anti-radiation and anti-oxidative activity of iron(III) complex of low molecular-weight polysaccharides were not less than that of low molecular-weight polysaccharides. Copyright © 2013 Elsevier B.V. All rights reserved.

Gas chromatography/mass spectrometry based component profiling and quality prediction for Japanese sake.

PubMed

Mimura, Natsuki; Isogai, Atsuko; Iwashita, Kazuhiro; Bamba, Takeshi; Fukusaki, Eiichiro

2014-10-01

Sake is a Japanese traditional alcoholic beverage, which is produced by simultaneous saccharification and alcohol fermentation of polished and steamed rice by Aspergillus oryzae and Saccharomyces cerevisiae. About 300 compounds have been identified in sake, and the contribution of individual components to the sake flavor has been examined at the same time. However, only a few compounds could explain the characteristics alone and most of the attributes still remain unclear. The purpose of this study was to examine the relationship between the component profile and the attributes of sake. Gas chromatography coupled with mass spectrometry (GC/MS)-based non-targeted analysis was employed to obtain the low molecular weight component profile of Japanese sake including both nonvolatile and volatile compounds. Sake attributes and overall quality were assessed by analytical descriptive sensory test and the prediction model of the sensory score from the component profile was constructed by means of orthogonal projections to latent structures (OPLS) regression analysis. Our results showed that 12 sake attributes [ginjo-ka (aroma of premium ginjo sake), grassy/aldehydic odor, sweet aroma/caramel/burnt odor, sulfury odor, sour taste, umami, bitter taste, body, amakara (dryness), aftertaste, pungent/smoothness and appearance] and overall quality were accurately explained by component profiles. In addition, we were able to select statistically significant components according to variable importance on projection (VIP). Our methodology clarified the correlation between sake attribute and 200 low molecular components and presented the importance of each component thus, providing new insights to the flavor study of sake. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Generation of a large volume of clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles for cell culture studies

PubMed Central

Ingham, Eileen; Fisher, John; Tipper, Joanne L

2014-01-01

It has recently been shown that the wear of ultra-high-molecular-weight polyethylene in hip and knee prostheses leads to the generation of nanometre-sized particles, in addition to micron-sized particles. The biological activity of nanometre-sized ultra-high-molecular-weight polyethylene wear particles has not, however, previously been studied due to difficulties in generating sufficient volumes of nanometre-sized ultra-high-molecular-weight polyethylene wear particles suitable for cell culture studies. In this study, wear simulation methods were investigated to generate a large volume of endotoxin-free clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles. Both single-station and six-station multidirectional pin-on-plate wear simulators were used to generate ultra-high-molecular-weight polyethylene wear particles under sterile and non-sterile conditions. Microbial contamination and endotoxin levels in the lubricants were determined. The results indicated that microbial contamination was absent and endotoxin levels were low and within acceptable limits for the pharmaceutical industry, when a six-station pin-on-plate wear simulator was used to generate ultra-high-molecular-weight polyethylene wear particles in a non-sterile environment. Different pore-sized polycarbonate filters were investigated to isolate nanometre-sized ultra-high-molecular-weight polyethylene wear particles from the wear test lubricants. The use of the filter sequence of 10, 1, 0.1, 0.1 and 0.015 µm pore sizes allowed successful isolation of ultra-high-molecular-weight polyethylene wear particles with a size range of < 100 nm, which was suitable for cell culture studies. PMID:24658586

Generation of a large volume of clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles for cell culture studies.

PubMed

Liu, Aiqin; Ingham, Eileen; Fisher, John; Tipper, Joanne L

2014-04-01

It has recently been shown that the wear of ultra-high-molecular-weight polyethylene in hip and knee prostheses leads to the generation of nanometre-sized particles, in addition to micron-sized particles. The biological activity of nanometre-sized ultra-high-molecular-weight polyethylene wear particles has not, however, previously been studied due to difficulties in generating sufficient volumes of nanometre-sized ultra-high-molecular-weight polyethylene wear particles suitable for cell culture studies. In this study, wear simulation methods were investigated to generate a large volume of endotoxin-free clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles. Both single-station and six-station multidirectional pin-on-plate wear simulators were used to generate ultra-high-molecular-weight polyethylene wear particles under sterile and non-sterile conditions. Microbial contamination and endotoxin levels in the lubricants were determined. The results indicated that microbial contamination was absent and endotoxin levels were low and within acceptable limits for the pharmaceutical industry, when a six-station pin-on-plate wear simulator was used to generate ultra-high-molecular-weight polyethylene wear particles in a non-sterile environment. Different pore-sized polycarbonate filters were investigated to isolate nanometre-sized ultra-high-molecular-weight polyethylene wear particles from the wear test lubricants. The use of the filter sequence of 10, 1, 0.1, 0.1 and 0.015 µm pore sizes allowed successful isolation of ultra-high-molecular-weight polyethylene wear particles with a size range of < 100 nm, which was suitable for cell culture studies.

Adsorption of Poly(methyl methacrylate) on Concave Al2O3 Surfaces in Nanoporous Membranes

PubMed Central

Nunnery, Grady; Hershkovits, Eli; Tannenbaum, Allen; Tannenbaum, Rina

2009-01-01

The objective of this study was to determine the influence of polymer molecular weight and surface curvature on the adsorption of polymers onto concave surfaces. Poly(methyl methacrylate) (PMMA) of various molecular weights was adsorbed onto porous aluminum oxide membranes having various pore sizes, ranging from 32 to 220 nm. The surface coverage, expressed as repeat units per unit surface area, was observed to vary linearly with molecular weight for molecular weights below ~120 000 g/mol. The coverage was independent of molecular weight above this critical molar mass, as was previously reported for the adsorption of PMMA on convex surfaces. Furthermore, the coverage varied linearly with pore size. A theoretical model was developed to describe curvature-dependent adsorption by considering the density gradient that exists between the surface and the edge of the adsorption layer. According to this model, the density gradient of the adsorbed polymer segments scales inversely with particle size, while the total coverage scales linearly with particle size, in good agreement with experiment. These results show that the details of the adsorption of polymers onto concave surfaces with cylindrical geometries can be used to calculate molecular weight (below a critical molecular weight) if pore size is known. Conversely, pore size can also be determined with similar adsorption experiments. Most significantly, for polymers above a critical molecular weight, the precise molecular weight need not be known in order to determine pore size. Moreover, the adsorption developed and validated in this work can be used to predict coverage also onto surfaces with different geometries. PMID:19415910

Low-molecular weight fractions of Japanese soy sauce act as a RAGE antagonist via inhibition of RAGE trafficking to lipid rafts.

PubMed

Munesue, Seiichi; Yamamoto, Yasuhiko; Urushihara, Ryouta; Inomata, Kouhei; Saito, Hidehito; Motoyoshi, So; Watanabe, Takuo; Yonekura, Hideto; Yamamoto, Hiroshi

2013-12-01

Advanced glycation end-products (AGE) have been implicated in aging and the pathogenesis of diabetic complications, inflammation, Alzheimer's disease, and cancer. AGE engage the cell surface receptor for AGE (RAGE), which in turn elicits intracellular signaling, leading to activation of NF-κB to cause deterioration of tissue homeostasis. AGE are not only formed within our bodies but are also derived from foods, endowing them with flavor. In the present study, we assessed the agonistic/antagonistic effects of food-derived AGE on RAGE signaling in a reporter assay system and found that low-molecular weight AGE can antagonize the action of AGE-BSA. Foods tested were Japanese soy sauce, coffee, cola, and red wine, all of which showed fluorescence characteristics of AGE. Soy sauce and coffee contained N(ε)-carboxymethyl-lysine (CML). Soy sauce, coffee, and red wine inhibited the RAGE ligand-induced activation of NF-κB, whereas cola had no effect on the ligand induction of NF-κB. The liquids were then fractionated into high-molecular weight (HMW) fractions and low-molecular weight (LMW) fractions. Soy sauce-, coffee-, and red wine-derived LMW fractions consistently inhibited the RAGE ligand induction of NF-κB, whereas the HMW fractions of these foods activated RAGE signaling. Using the LMW fraction of soy sauce as a model food-derived RAGE antagonist, we performed a plate-binding assay and found that the soy sauce LMW fractions competitively inhibited AGE-RAGE association. Further, this fraction significantly reduced AGE-dependent monocyte chemoattractant protein-1 (MCP-1) secretion from murine peritoneal macrophages. The LMF from soy sauce suppressed the AGE-induced RAGE trafficking to lipid rafts. These results indicate that small components in some, if not all, foods antagonize RAGE signaling and could exhibit beneficial effects on RAGE-related diseases.

The Molecular Weight Distribution of Polymer Samples

ERIC Educational Resources Information Center

Horta, Arturo; Pastoriza, M. Alejandra

2007-01-01

Various methods for the determination of the molecular weight distribution (MWD) of different polymer samples are presented. The study shows that the molecular weight averages and distribution of a polymerization completely depend on the characteristics of the reaction itself.

Dissolved and colloidal copper in the tropical South Pacific

NASA Astrophysics Data System (ADS)

Roshan, Saeed; Wu, Jingfeng

2018-07-01

Copper (Cu) as a bioactive trace metal in the ocean has widely been studied in the context of chemical speciation. However, this trace metal is extremely understudied in the context of physical speciation (i.e., size- or molecular weight-partitioning), which may help in characterizing dissolved Cu species. In this study, we determine total dissolved Cu (<0.2 μm) distribution and its physical speciation along the US GEOTRACES 2013 cruise, a 4300-km east-west transect in the tropical South Pacific. The distribution of dissolved Cu is rather uniform horizontally and exhibits a linear increase with depth from surface to 2500-3000 m, below which it varies less significantly both vertically and horizontally. Dissolved Cu shows a strong correlation with silicate (SiO44-) in the upper 1500 m, which is in agreement with previous studies in other regions. This correlation is weaker but with higher slope at depths below 1500 m, which supports the sedimentary source hypothesis. Although hydrothermal activity at the East Pacific Rise (EPR) does not show a readily evident impact on the dissolved Cu distribution, high-quality data at 2300-2800 m allow for diagnosing a subtle westward decrease in the background-subtracted dissolved Cu component. This component of dissolved Cu poorly correlates with mantle-derived 3He (R2 = 0.41), indicating a possible hydrothermal source for dissolved Cu, in contrast to previous studies. For the first time in a major basin, we also determined the physical speciation of dissolved Cu, which shows that Cu species lighter than 10 kDa (Da = 1 g mol-1) dominate the pool of dissolved Cu (<0.2 μm) below 1000 m with a contribution of 61 ± 6% (fraction of total dissolved). 39 ± 6% of dissolved Cu at depths below 1000 m, thus, occurs in the pool of colloidal matter (10 kDa-0.2 μm). Moreover, using a suite of molecular weight cutoffs indicate that Cu species are distributed between two distinct molecular weight classes: the lighter than 5 kDa and heavier than 300 kDa classes, which form 53 ± 6% and 37 ± 7% of dissolved Cu at 2200-2800 m, respectively. The Cu species with molecular weight between 5 kDa and 300 kDa contribute only to 10 ± 12% of the pool at 2200-2800 m. These results offer new insights into structure, reactivity and bioavailability of oceanic Cu compounds. As an organic-dominating metal, Cu physical speciation may also shed light on size-reactivity spectrum of dissolved organic matter (DOM) in the deep ocean.

The effect of liquid hot water pretreatment on the chemical-structural alteration and the reduced recalcitrance in poplar.

PubMed

Li, Mi; Cao, Shilin; Meng, Xianzhi; Studer, Michael; Wyman, Charles E; Ragauskas, Arthur J; Pu, Yunqiao

2017-01-01

Hydrothermal pretreatment using liquid hot water (LHW) is capable of substantially reducing the cell wall recalcitrance of lignocellulosic biomass. It enhances the saccharification of polysaccharides, particularly cellulose, into glucose with relatively low capital required. Due to the close association with biomass recalcitrance, the structural change of the components of lignocellulosic materials during the pretreatment is crucial to understand pretreatment chemistry and advance the bio-economy. Although the LHW pretreatment has been extensively applied and studied, the molecular structural alteration during pretreatment and its significance to reduced recalcitrance have not been well understood. We investigated the effects of LHW pretreatment with different severity factors (log R 0 ) on the structural changes of fast-grown poplar ( Populus trichocarpa ). With the severity factor ranging from 3.6 to 4.2, LHW pretreatment resulted in a substantial xylan solubilization by 50-77% ( w/w , dry matter). The molecular weights of the remained hemicellulose in pretreated solids also have been significantly reduced by 63-75% corresponding to LHW severity factor from 3.6 to 4.2. In addition, LHW had a considerable impact on the cellulose structure. The cellulose crystallinity increased 6-9%, whereas its degree of polymerization decreased 35-65% after pretreatment. We found that the pretreatment severity had an empirical linear correlation with the xylan solubilization ( R 2  = 0.98, r  = + 0.99), hemicellulose molecular weight reduction ( R 2  = 0.97, r  = - 0.96 and R 2  = 0.93, r  = - 0.98 for number-average and weight-average degree of polymerization, respectively), and cellulose crystallinity index increase ( R 2  = 0.98, r  = + 0.99). The LHW pretreatment also resulted in small changes in lignin structure such as decrease of β- O -4' ether linkages and removal of cinnamyl alcohol end group and acetyl group, while the S/G ratio of lignin in LHW pretreated poplar residue remained no significant change compared with the untreated poplar. This study revealed that the solubilization of xylan, the reduction of hemicellulose molecular weights and cellulose degree of polymerization, and the cleavage of alkyl-aryl ether bonds in lignin resulted from LHW pretreatment are critical factors associated with reduced cell wall recalcitrance. The chemical-structural changes of the three major components, cellulose, lignin, and hemicellulose, during LHW pretreatment provide useful and fundamental information of factors governing feedstock recalcitrance during hydrothermal pretreatment.

Understanding gas-surface interactions from direct force measurements using a specialized torsion balance

NASA Technical Reports Server (NTRS)

Cook, S. R.; Hoffbauer, M. A.

1996-01-01

The first comprehensive measurements of the magnitude and direction of the forces exerted on surfaces by molecular beams are discussed and used to obtain information about the microscopic properties of the gas-surface interactions. This unique approach is not based on microscopic measurements of the scattered molecules. The reduced force coefficients are introduced as a new set of parameters that completely describe the macroscopic average momentum transfer to a surface by an incident molecular beam. By using a specialized torsion balance and molecular beams of N2, CO, CO2, and H2, the reduced force coefficients are determined from direct measurements of the force components exerted on surface of a solar panel array material, Kapton, SiO2-coated Kapton, and Z-93 as a function of the angle of incidence ranging from 0 degrees to 85 degrees. The absolute flux densities of the molecular beams were measured using a different torsion balance with a beam-stop that nullified the force of the scattered molecules. Standard time-of-flight techniques were used to determine the flux-weighted average velocities of the various molecular beams ranging from 1600 m/s to 4600 m/s. The reduced force coefficients can be used to directly obtain macroscopic average properties of the scattered molecules, such as the flux-weighted average velocity and translational energy, that can then be used to determine microscopic details concerning gas-surface interactions without the complications associated with averaging microscopic measurements.

Parameters and pitfalls to consider in the conduct of food additive research, Carrageenan as a case study.

PubMed

Weiner, Myra L

2016-01-01

This paper provides guidance on the conduct of new in vivo and in vitro studies on high molecular weight food additives, with carrageenan, the widely used food additive, as a case study. It is important to understand the physical/chemical properties and to verify the identity/purity, molecular weight and homogeneity/stability of the additive in the vehicle for oral delivery. The strong binding of CGN to protein in rodent chow or infant formula results in no gastrointestinal tract exposure to free CGN. It is recommended that doses of high Mw non-caloric, non-nutritive additives not exceed 5% by weight of total solid diet to avoid potential nutritional effects. Addition of some high Mw additives at high concentrations to liquid nutritional supplements increases viscosity and may affect palatability, caloric intake and body weight gain. In in vitro studies, the use of well-characterized, relevant cell types and the appropriate composition of the culture media are necessary for proper conduct and interpretation. CGN is bound to media protein and not freely accessible to cells in vitro. Interpretation of new studies on food additives should consider the interaction of food additives with the vehicle components and the appropriateness of the animal or cell model and dose-response. Copyright © 2015 FMC Corporation. Published by Elsevier Ltd.. All rights reserved.

Main Quality Attributes of Monoclonal Antibodies and Effect of Cell Culture Components

PubMed

Torkashvand, Fatemeh; Vaziri, Behrouz

2017-05-01

The culture media optimization is an inevitable part of upstream process development in therapeutic monoclonal antibodies (mAbs) production. The quality by design (QbD) approach defines the assured quality of the final product through the development stage. An important step in QbD is determination of the main quality attributes. During the media optimization, some of the main quality attributes such as glycosylation pattern, charge variants, aggregates, and low-molecular-weight species, could be significantly altered. Here, we provide an overview of how cell culture medium components affects the main quality attributes of the mAbs. Knowing the relationship between the culture media components and the main quality attributes could be successfully utilized for a rational optimization of mammalian cell culture media for industrial mAbs production.

Molecular weight dependency of polyrotaxane-cross-linked polymer gel extensibility.

PubMed

Ohmori, Kana; Abu Bin, Imran; Seki, Takahiro; Liu, Chang; Mayumi, Koichi; Ito, Kohzo; Takeoka, Yukikazu

2016-12-11

This work investigates the influence of the molecular weight of polyrotaxane (PR) cross-linkers on the extensibility of polymer gels. The polymer gels, which were prepared using PR cross-linkers of three different molecular weights but the same number of cross-linking points per unit volume of gel, have almost the same Young's modulus. By contrast, the extensibility and rupture strength of the polymer gels are substantially increased with increasing molecular weight of the PR cross-linker.

Combustion of High Molecular Weight Hydrocarbon Fuels and JP-8 at Moderate Pressures

DTIC Science & Technology

2016-07-26

SECURITY CLASSIFICATION OF: The objective of this research is to characterize combustion of high molecular weight hydrocarbon fuels and jet- fuels (in...Unlimited UU UU UU UU 26-07-2016 1-May-2012 30-Apr-2016 Final Report: Combustion of High Molecular Weight Hydrocarbon Fuels and JP-8 at Moderate...Report: Combustion of High Molecular Weight Hydrocarbon Fuels and JP-8 at Moderate Pressures (Research Area 1: Mechanical Sciences) Report Title The

Release of low molecular weight silicones and platinum from silicone breast implants.

PubMed

Lykissa, E D; Kala, S V; Hurley, J B; Lebovitz, R M

1997-12-01

We have conducted a series of studies addressing the chemical composition of silicone gels from breast implants as well as the diffusion of low molecular weight silicones (LM-silicones) and heavy metals from intact implants into various surrounding media, namely, lipid-rich medium (soy oil), aqueous tissue culture medium (modified Dulbecco's medium, DMEM), or an emulsion consisting of DMEM plus 10% soy oil. LM-silicones in both implants and surrounding media were detected and quantitated using gas chromatography (GC) coupled with atomic emission (GC-AED) as well as mass spectrometric (GC/MS) detectors, which can detect silicones in the nanogram range. Platinum, a catalyst used in the preparation of silicone gels, was detected and quantitated using inductive argon-coupled plasma/mass spectrometry (ICP-MS), which can detect platinum in the parts per trillion range. Our results indicate that GC-detectable low molecular weight silicones contribute approximately 1-2% to the total gel mass and consist predominantly of cyclic and linear poly-(dimethylsiloxanes) ranging from 3 to 20 siloxane [(CH3)2-Si-O] units (molecular weight 200-1500). Platinum can be detected in implant gels at levels of approximately 700 micrograms/kg by ICP-MS. The major component of implant gels appears to be high molecular weight silicone polymers (HM-silicones) too large to be detected by GC. However, these HM-silicones can be converted almost quantitatively (80% by mass) to LM-silicones by heating implant gels at 150-180 degrees C for several hours. We also studied the rates at which LM-silicones and platinum leak through the intact implant outer shell into the surrounding media under a variety of conditions. Leakage of silicones was greatest when the surrounding medium was lipid-rich, and up to 10 mg/day LM-silicones was observed to diffuse into a lipid-rich medium per 250 g of implant at 37 degrees C. This rate of leakage was maintained over a 7-day experimental period. Similarly, platinum was also observed to leak through intact implants into lipid-containing media at rates of approximately 20-25 micrograms/day/250 g of implant at 37 degrees C. The rates at which both LM-silicones and platinum have been observed to leak from intact implants could lead to significant accumulation within lipid-rich tissues and should be investigated more fully in vivo.

Application of the weibull distribution function to the molecular weight distribution of cellulose

Treesearch

A. Broido; Hsiukang Yow

1977-01-01

The molecular weight distribution of a linear homologous polymer is usually obtained empirically for any particular sample. Sample-to-sample comparisons are made in terms of the weight- or number-average molecular weights and graphic displays of the distribution curves. Such treatment generally precludes data interpretations in which a distribution can be described in...

Chemistry of gluten proteins.

PubMed

Wieser, Herbert

2007-04-01

Gluten proteins play a key role in determining the unique baking quality of wheat by conferring water absorption capacity, cohesivity, viscosity and elasticity on dough. Gluten proteins can be divided into two main fractions according to their solubility in aqueous alcohols: the soluble gliadins and the insoluble glutenins. Both fractions consist of numerous, partially closely related protein components characterized by high glutamine and proline contents. Gliadins are mainly monomeric proteins with molecular weights (MWs) around 28,000-55,000 and can be classified according to their different primary structures into the alpha/beta-, gamma- and omega-type. Disulphide bonds are either absent or present as intrachain crosslinks. The glutenin fraction comprises aggregated proteins linked by interchain disulphide bonds; they have a varying size ranging from about 500,000 to more than 10 million. After reduction of disulphide bonds, the resulting glutenin subunits show a solubility in aqueous alcohols similar to gliadins. Based on primary structure, glutenin subunits have been divided into the high-molecular-weight (HMW) subunits (MW=67,000-88,000) and low-molecular-weight (LMW) subunits (MW=32,000-35,000). Each gluten protein type consists or two or three different structural domains; one of them contains unique repetitive sequences rich in glutamine and proline. Native glutenins are composed of a backbone formed by HMW subunit polymers and of LMW subunit polymers branched off from HMW subunits. Non-covalent bonds such as hydrogen bonds, ionic bonds and hydrophobic bonds are important for the aggregation of gliadins and glutenins and implicate structure and physical properties of dough.

Hemorrhagic shock and surgical stress alter distribution of labile zinc within high- and low-molecular-weight plasma fractions.

PubMed

Kelly, Edward; Mathew, Jeff; Kohler, Jonathan E; Blass, Amy L; Soybel, And David I

2012-08-01

Zinc ions (Zn) are essential for tissue repair following injury or stress. We hypothesize that during such stresses Zn is redistributed to labile pools in plasma components. Here we tested this hypothesis using a novel assay to monitor labile Zn in plasma in hemorrhagic shock. Adult rats in the shock group (S group) underwent hemorrhage and resuscitation. Blood samples were drawn at baseline and at 1, 4, and 24 h. The surgical control group (SC group) was anesthetized and instrumented, but not bled. Albumin, total Zn, and labile Zn levels were assayed in plasma. Binding capacity for Zn was assessed in high- and low-molecular-weight pools. Significant decreases in total Zn were observed by 24 h, in both S and SC groups. Albumin levels were significantly reduced in the S group at 1 and 4 h but restored at 24 h; significant changes were not observed in other groups. In whole plasma, labile Zn levels were stable initially in the S and SC groups, but declined at 24 h. In the high-molecular-weight pool, marked and significant impairment of binding was noted throughout all time periods following the shock period in the S group. Such changes were observed in the SC group of less intensity and duration. These experiments suggest that shock alters affinity of plasma proteins for Zn, promoting delivery to peripheral tissues during periods of increased Zn utilization.

Comparative evaluation of western blotting in hepatic and pulmonary cystic echinococcosis.

PubMed

Akisu, C; Delibas, S B; Bicmen, C; Ozkoc, S; Aksoy, U; Turgay, N

2006-12-01

Many serological tests are widely used in the diagnosis of cystic echinococcosis (CE), caused by the larval stages of Echinococcus granulosus. The present study was carried for differentiation between hepatic and pulmonary cystic echinococcosis by Western Blotting (WB). A total of 121 sera from patients with hepatic CE (37), pulmonary CE (31) and controls (53; consisting of six healthy, seven Hymenolepis nana infection, 20 hepatic and 20 pulmonary diseases other than CE) were examined. In all of the CE patients, E. gronulosus infection was confirmed by surgical intervention. Sera were previously tested using IHA and ELISA to detect the E. gronulosus specific antibodies. Sera from hepatic cases of CE reacted with 16 polypeptides of 6-116 kDa and sera from pulmonary cases of CE reacted with 14 polypeptides of 4-130 kDa by Western Blotting. The WB test enabled the detection of antibodies in the hepatic CE samples for proteins of 24, 32 34, 44-46 and 52-54 kDa in molecular weight in 78.4%, 75.7%, 78.4% and 89.2% of the patients, respectively. In the pulmonary CE samples sera WB test enabled the detection of antibodies 24, 44-46, 100, 110, 116 and 120 124 kDa in molecular weight in 81.3%, 75.0%, 87.5%, 71.9%, 84.4% and 65.6% of the patients, respectively. We indicated that the antigenic components of high molecular weight can be good candidates for differentiation of hepatic CE from pulmonary CE.

Isolation, purification, and partial characterization of Brucella abortus matrix protein.

PubMed Central

Moriyon, I; Berman, D T

1983-01-01

Peptidoglycan sacculi with peptidoglycan-associated proteins were prepared from cell envelopes of Brucella abortus by extraction with sodium dodecyl sulfate (SDS) at 50 degrees C. On extraction of these preparations with SDS at 100 degrees C, a protein was obtained whose removal from peptidoglycan was confirmed by electron microscopy. Incubation of the 50 degrees C SDS-extracted cell envelopes with 50 mM MgCl2 in SDS-2-beta-mercaptoethanol at 37 degrees C also extracted the protein, along with lipopolysaccharide. At temperatures below 60 degrees C, the protein did not bind SDS strongly and had an apparent molecular weight greater than 92,000 in SDS-polyacrylamide gel electrophoresis. At higher temperatures, SDS bound strongly, and the apparent molecular weight was 38,000. Urea at 5 M did not alter the electrophoretic mobility of this 38,000-molecular-weight form. Immunoelectrophoresis in detergents with antisera to cell envelopes, carbohydrate staining of SDS-polyacrylamide gels, and production of anti-lipopolysaccharide antibodies by mice immunized with the purified protein indicated that lipopolysaccharide was present in free and protein-bound forms. Sequential gel filtration in SDS-EDTA and SDS-NaCl removed most lipopolysaccharide. After further purification by preparative SDS-polyacrylamide gel electrophoresis, a gas-liquid chromatographic analysis showed residual lipid tightly associated with the protein. The results suggested that the interactions between matrix proteins and other outer membrane components are stronger in B. abortus than in Escherichia coli, which was used as a control throughout. Images PMID:6401696

Catalysts and process for liquid hydrocarbon fuel production

DOEpatents

White, Mark G.; Ranaweera, Samantha A.; Henry, William P.

2016-08-02

The present invention provides a novel process and system in which a mixture of carbon monoxide and hydrogen synthesis gas, or syngas, is converted into hydrocarbon mixtures composed of high quality distillates, gasoline components, and lower molecular weight gaseous olefins in one reactor or step. The invention utilizes a novel supported bimetallic ion complex catalyst for conversion, and provides methods of preparing such novel catalysts and use of the novel catalysts in the process and system of the invention.

Synthesis of high molecular weight PEO using non-metal initiators

DOEpatents

Yang, Jin; Sivanandan, Kulandaivelu; Pistorino, Jonathan; Eitouni, Hany Basam

2015-05-19

A new synthetic method to prepare high molecular weight poly(ethylene oxide) with a very narrow molecular weight distribution (PDI<1.5) is described. The method involves a metal free initiator system, thus avoiding dangerous, flammable organometallic compounds.

Investigation of CO2 precursors in roasted coffee.

PubMed

Wang, Xiuju; Lim, Loong-Tak

2017-03-15

Two CO 2 formation pathways (chlorogenic acid (CGA) degradation and Maillard reaction) during coffee roasting were investigated. CGA is shown not a major contributor to CO 2 formation, as heating of this compound under typical roasting conditions did not release a large quantity of CO 2 . However, heating of a CGA moiety, caffeic acid, resulted in high yield of CO 2 (>98%), suggesting that CGA hydrolysis could be the rate limiting step for CO 2 formation from CGA. A large amount of CO 2 was detected from glycine-sucrose model system under coffee roasting conditions, implying the importance of Maillard reactions in CO 2 formation. Further studies on the heating of various components isolated from green coffee beans showed that CO 2 was generated from various green coffee components, including water insoluble proteins and polysaccharides. Around 50% of CO 2 was formed from thermal reactions of lower molecular weight compounds that represent ∼25% by weight in green coffee. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fluorescence spectroscopy as a specific tool for the interaction study of two surfactants with natural and synthetic organic compounds

NASA Astrophysics Data System (ADS)

Jung, Aude-Valérie; Frochot, Céline; Bersillon, Jean-Luc

2016-04-01

Four different techniques were used to study the binding of cationic cetyltrimethylammonium bromide (CTAB) and non-ionic nonylphenylethoxyl (NPE) surfactants to three synthetic organic components that mimic humic-like aggregates and to two natural aggregated humic substances (HS) extracted from aquatic suspended matter. The composition of synthetic organic components were chosen to be similar to high molecular weight highly processed terrigenous HS and low and high molecular weight less processed terrigenous (or aquatic terrigenous) HS. The natural HS were extracted under two different meteorological conditions (rainy and dry periods). No significant interaction between the non-ionic surfactant and any of the studied compounds was found. Concerning CTAB; pH, conductivity and turbidity measurements, along with fluorescence spectroscopy were combined to provide a better understanding of interactions between organic aggregates and the surfactant. The spectroscopic data show that a "highly processed terrigenous HS" fluorophore interacts in a different way with the cationic surfactant than an "aquatic terrigenous (or less processed terrigenous) HS" fluorophore does. Under similar conditions, some spectral changes in the fluorescence signal are correlated to changes in non-specific physical-chemical parameters (pH, turbidity, conductivity) for the organic compounds tested. The complexation mechanism is essentially governed by charge neutralization, which can be monitored specifically by the fluorescence of the organic moieties.

PETIs as High-Temperature Resin-Transfer-Molding Materials

NASA Technical Reports Server (NTRS)

Connell, John N.; Smith, Joseph G., Jr.; Hergenrother, Paul M.

2005-01-01

Compositions of, and processes for fabricating, high-temperature composite materials from phenylethynyl-terminated imide (PETI) oligomers by resin-transfer molding (RTM) and resin infusion have been developed. Composites having a combination of excellent mechanical properties and long-term high-temperature stability have been readily fabricated. These materials are particularly useful for the fabrication of high-temperature structures for jet-engine components, structural components on highspeed aircraft, spacecraft, and missiles. Phenylethynyl-terminated amide acid oligomers that are precursors of PETI oligomers are easily made through the reaction of a mixture of aromatic diamines with aromatic dianhydrides at high stoichiometric offsets and 4-phenylethynylphthalic anhydride (PEPA) as an end-capper in a polar solvent such as N-methylpyrrolidinone (NMP). These oligomers are subsequently cyclodehydrated -- for example, by heating the solution in the presence of toluene to remove the water by azeotropic distillation to form low-molecular-weight imide oligomers. More precisely, what is obtained is a mixture of PETI oligomeric species, spanning a range of molecular weights, that exhibits a stable melt viscosity of less than approximately 60 poise (and generally less than 10 poise) at a temperature below 300 deg C. After curing of the oligomers at a temperature of 371 deg C, the resulting polymer can have a glass-transition temperature (Tg) as high as 375 C, the exact value depending on the compositions.

The competing effects of microbially derived polymeric and low molecular-weight substances on the dispersibility of CeO2 nanoparticles

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

Nakano, Yuriko; Ochiai, Asumi; Kawamoto, Keisuke

To understand the competing effects of the components in extracellular substances (ES), polymeric substances (PS) and low-molecular-weight small substances (SS) <1 kDa derived from microorganisms, on the colloidal stability of cerium dioxide nanoparticles (CeNPs), we investigated their adsorption to sparingly soluble CeNPs at room temperature at pH 6.0. The ES was extracted from the fungus S. cerevisiae. The polypeptides and phosphates in all components preferentially adsorbed onto the CeNPs. The zeta potentials of ES + CeNPs, PS + CeNPs, and SS + CeNPs overlapped on the plot of PS itself, indicating the surface charge of the polymeric substances controls themore » zeta potentials. The sizes of the CeNP aggregates, 100–1300 nm, were constrained by the zeta potentials. The steric barrier derived from the polymers, even in SS, enhanced the CeNP dispersibility at pH 1.5–10. Consequently, the PS and SS had similar effects on modifying the CeNP surfaces. The adsorption of ES, which contains PS + SS, can suppress the aggregation of CeNPs over a wider pH range than that for PS only. The present study addresses the non-negligible effects of small-sized molecules derived from microbial activity on the migration of CeNP in aquatic environments, especially where bacterial consortia prevail.« less

Body weight-dependent troponin T alternative splicing is evolutionarily conserved from insects to mammals and is partially impaired in skeletal muscle of obese rats.

PubMed

Schilder, Rudolf J; Kimball, Scot R; Marden, James H; Jefferson, Leonard S

2011-05-01

Do animals know at a physiological level how much they weigh, and, if so, do they make homeostatic adjustments in response to changes in body weight? Skeletal muscle is a likely tissue for such plasticity, as weight-bearing muscles receive mechanical feedback regarding body weight and consume ATP in order to generate forces sufficient to counteract gravity. Using rats, we examined how variation in body weight affected alternative splicing of fast skeletal muscle troponin T (Tnnt3), a component of the thin filament that regulates the actin-myosin interaction during contraction and modulates force output. In response to normal growth and experimental body weight increases, alternative splicing of Tnnt3 in rat gastrocnemius muscle was adjusted in a quantitative fashion. The response depended on weight per se, as externally attached loads had the same effect as an equal change in actual body weight. Examining the association between Tnnt3 alternative splicing and ATP consumption rate, we found that the Tnnt3 splice form profile had a significant association with nocturnal energy expenditure, independently of effects of weight. For a subset of the Tnnt3 splice forms, obese Zucker rats failed to make the same adjustments; that is, they did not show the same relationship between body weight and the relative abundance of five Tnnt3 β splice forms (i.e. Tnnt3 β2-β5 and β8), four of which showed significant effects on nocturnal energy expenditure in Sprague-Dawley rats. Heavier obese Zucker rats displayed certain splice form relative abundances (e.g. Tnnt3 β3) characteristic of much lighter, lean animals, resulting in a mismatch between body weight and muscle molecular composition. Consequently, we suggest that body weight-inappropriate skeletal muscle Tnnt3 expression in obesity is a candidate mechanism for muscle weakness and reduced mobility. Weight-dependent quantitative variation in Tnnt3 alternative splicing appears to be an evolutionarily conserved feature of skeletal muscle and provides a quantitative molecular marker to track how an animal perceives and responds to body weight.

All-acrylic multigraft copolymers: Effect of side chain molecular weight and volume fraction on mechanical behavior

DOE PAGES

Goodwin, Andrew; Wang, Weiyu; Kang, Nam -Goo; ...

2015-08-21

We present in this paper the synthesis of poly(n-butyl acrylate)-g-poly(methyl methacrylate) (PnBA-g-PMMA) multigraft copolymers via a grafting-through (macromonomer) approach. The synthesis was performed using two controlled polymerization techniques. The PMMA macromonomer was obtained by high-vacuum anionic polymerization followed by the copolymerization of n-butyl acrylate and PMMA macromonomer using reversible addition–fragmentation chain transfer (RAFT) polymerization to yield the desired all-acrylic multigraft structures. The PnBA-g-PMMA multigraft structures exhibit randomly spaced branch points with various PMMA contents, ranging from 15 to 40 vol %, allowing an investigation into how physical properties vary with differences in the number of branch points and molecular weightmore » of grafted side chains. The determination of molecular weight and polydispersity indices of both the PMMA macromonomer and the graft copolymers was carried out using size exclusion chromatography with triple detection, and the structural characteristics of both the macromonomer and PnBA-g-PMMA graft materials were characterized by 1H and 13C NMR. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was employed for monitoring the macromonomer synthesis. Thermal characteristics of the materials were analyzed using differential scanning calorimetry and thermogravimetric analysis. The mechanical performance of the graft materials was characterized by rheology and dynamic mechanical analysis, revealing that samples with PMMA content of 25–40 vol % exhibit superior elastomeric properties as compared to materials containing short PMMA side chains or <25 vol % PMMA. In conclusion, atomic force microscopy showed a varying degree of microphase separation between the glassy and rubbery components that is strongly dependent on PMMA side chain molecular weight.« less

Fermented Papaya Preparation Restores Age-Related Reductions in Peripheral Blood Mononuclear Cell Cytolytic Activity in Tube-Fed Patients

PubMed Central

Fujita, Yuhzo; Tsuno, Haruo; Nakayama, Jiro

2017-01-01

Tube-fed elderly patients are generally supplied with the same type of nutrition over long periods, resulting in an increased risk for micronutrient deficiencies. Dietary polyphenols promote immunity and have anti-inflammatory, anti-carcinogenic, and anti-oxidative properties. Carica papaya Linn. is rich in several polyphenols; however, these polyphenols are poorly absorbed from the digestive tract in their original polymerized form. Therefore, we determined the molecular components of a fermented Carica papaya Linn. preparation, as well as its effects on immunity and the composition of gut microbiota in tube-fed patients. Different doses of the fermented C. papaya L. preparation were administered to three groups of tube-fed patients for 30 days. Its effects on fecal microbiota composition and immunity were assessed by 16S rRNA gene sequencing and immune-marker analysis, respectively. The chemical composition of the fermented C. papaya L. preparation was analyzed by capillary electrophoresis- and liquid chromatography- time of flight mass spectrometry. The fermented C. papaya L. preparation restored peripheral blood mononuclear cell (PBMC) cytolytic activity; however, no other biomarkers of immunity were observed. Treatment with the preparation (9 g/day) significantly reduced the abundance of Firmicutes in the fecal microbiota. In particular, treatment reduced Clostridium scindens and Eggerthella lenta in most patients receiving 9 g/day. Chemical analysis identified low-molecular-weight phenolic acids as polyphenol metabolites; however, no polymerized, large-molecular-weight molecules were detected. Our study indicates that elderly patients who are tube-fed over the long-term have decreased PBMC cytolytic activity. In addition, low-molecular-weight polyphenol metabolites fermented from polymerized polyphenols restore PBMC cytolytic activity and modulate the composition of gut microbiota in tube-fed patients. PMID:28060858

Functional analysis of thioredoxin from the desert lichen-forming fungus, Endocarpon pusillum Hedwig, reveals its role in stress tolerance

PubMed Central

Li, Hui; Wei, Jiang-Chun

2016-01-01

Endocarpon pusillum is a lichen-forming fungus with an outstanding stress resistance property closely related to its antioxidant system. In this study, thioredoxin (Trx), one of the main components of antioxidant defense systems in E. pusillum (EpTrx), was characterized and analyzed both in transgenic yeasts and in vitro. Our analyses identified that the heterologous expression of EpTrx in the yeast Pichia pastoris significantly enhanced its resistance to osmotic and oxidative stresses. Assays in vitro showed EpTrx acted as a disulfide reductase as well as a molecular chaperone by assembling into various polymeric structures. Upon exposure to heat-shock stress, EpTrx exhibited weaker disulfide reductase activity but stronger chaperone activity, which coincided with the switching of the protein complexes from low molecular weight forms to high molecular weight complexes. Specifically, we found that Cys31 near but not at the active site was crucial in promoting the structural and functional transitions, most likely by accelerating the formation of intermolecular disulfide bond. Transgenic Saccharomyces cerevisiae harboring the native EpTrx exhibited stronger tolerance to oxidative, osmotic and high temperature stresses than the corresponding yeast strain containing the mutant EpTrx (C31S). Our results provide the first molecular evidence on how Trx influences stress response in lichen-forming fungi. PMID:27251605

Determination of the molecular weight of poly(ethylene glycol) in biological samples by reversed-phase LC-MS with in-source fragmentation.

PubMed

Warrack, Bethanne M; Redding, Brian P; Chen, Guodong; Bolgar, Mark S

2013-05-01

PEGylation has been widely used to improve the biopharmaceutical properties of therapeutic proteins and peptides. Previous studies have used multiple analytical techniques to determine the fate of both the therapeutic molecule and unconjugated poly(ethylene glycol) (PEG) after drug administration. A straightforward strategy utilizing liquid chromatography-mass spectrometry (LC-MS) to characterize high-molecular weight PEG in biologic matrices without a need for complex sample preparation is presented. The method is capable of determining whether high-MW PEG is cleaved in vivo to lower-molecular weight PEG species. Reversed-phase chromatographic separation is used to take advantage of the retention principles of polymeric materials whereby elution order correlates with PEG molecular weight. In-source collision-induced dissociation (CID) combined with selected reaction monitoring (SRM) or selected ion monitoring (SIM) mass spectrometry (MS) is then used to monitor characteristic PEG fragment ions in biological samples. MS provides high sensitivity and specificity for PEG and the observed retention times in reversed-phase LC enable estimation of molecular weight. This method was successfully used to characterize PEG molecular weight in mouse serum samples. No change in molecular weight was observed for 48 h after dosing.

Metabolism of AGEs – Bacterial AGEs Are Degraded by Metallo-Proteases

PubMed Central

Cohen-Or, Ifat; Katz, Chen; Ron, Eliora Z.

2013-01-01

Advanced Glycation End Products (AGEs) are the final products of non-enzymatic protein glycation that results in loss of protein structure and function. We have previously shown that in E. coli AGEs are continually formed as high-molecular weight protein complexes. Moreover, we showed that AGEs are removed from the cells by an active, ATP-dependent secretion and that these secreted molecules have low molecular weight. Taken together, these results indicate that E. coli contains a fraction of low molecular weight AGEs, in addition to the high-molecular weight AGEs. Here we show that the low-molecular weight AGEs originate from high-molecular weight AGEs by proteolytic degradation. Results of in-vitro and in vivo experiments indicated that this degradation is carried out not by the major ATP-dependent proteases that are responsible for the main part of bacterial protein quality control but by an alternative metal-dependent proteolysis. This proteolytic reaction is essential for the further secretion of AGEs from the cells. As the biochemical reactions involving AGEs are not yet understood, the implication of a metalloprotease in breakdown of high molecular weight AGEs and their secretion constitutes an important step in the understanding of AGEs metabolism. PMID:24130678

Metabolism of AGEs--bacterial AGEs are degraded by metallo-proteases.

PubMed

Cohen-Or, Ifat; Katz, Chen; Ron, Eliora Z

2013-01-01

Advanced Glycation End Products (AGEs) are the final products of non-enzymatic protein glycation that results in loss of protein structure and function. We have previously shown that in E. coli AGEs are continually formed as high-molecular weight protein complexes. Moreover, we showed that AGEs are removed from the cells by an active, ATP-dependent secretion and that these secreted molecules have low molecular weight. Taken together, these results indicate that E. coli contains a fraction of low molecular weight AGEs, in addition to the high-molecular weight AGEs. Here we show that the low-molecular weight AGEs originate from high-molecular weight AGEs by proteolytic degradation. Results of in-vitro and in vivo experiments indicated that this degradation is carried out not by the major ATP-dependent proteases that are responsible for the main part of bacterial protein quality control but by an alternative metal-dependent proteolysis. This proteolytic reaction is essential for the further secretion of AGEs from the cells. As the biochemical reactions involving AGEs are not yet understood, the implication of a metalloprotease in breakdown of high molecular weight AGEs and their secretion constitutes an important step in the understanding of AGEs metabolism.

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

PubMed

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 <4%. The correlation was also successfully applied to accurately estimate the molecular weight of HA produced by a recombinant Lactococcus lactis fermentation. Copyright © 2017 Elsevier B.V. All rights reserved.

How Molecular Structure Affects Mechanical Properties of an Advanced Polymer

NASA Technical Reports Server (NTRS)

Nicholson, Lee M.; Whitley, Karen S.; Gates, Thomas S.; Hinkley, Jeffrey A.

2000-01-01

density was performed over a range of temperatures below the glass transition temperature. The physical characterization, elastic properties and notched tensile strength all as a function of molecular weight and test temperature were determined. For the uncrosslinked SI material, it was shown that notched tensile strength is a strong function of both temperature and molecular weight, whereas stiffness is only a strong function of temperature. For the crosslinked PETI-SI material, it was shown that the effect of crosslinking significantly enhances the mechanical performance of the low molecular weight material; comparable to that exhibited by the high molecular weight material.

The effect of real-time aging on the oxidation and wear of highly cross-linked UHMWPE acetabular liners.

PubMed

Wannomae, Keith K; Christensen, Steven D; Freiberg, Andrew A; Bhattacharyya, Shayan; Harris, William H; Muratoglu, Orhun Kamil

2006-03-01

Irradiation decreases the wear of ultra-high molecular weight polyethylene (UHMWPE) but generates residual free radicals, precursors to long-term oxidation. Melting or annealing is used in quenching free radicals. We hypothesized that irradiated and once-annealed UHMWPE would oxidize while irradiated and melted UHMWPE would not, and that the oxidation in the former would increase wear. Acetabular liners were real-time aged by immersion in an aqueous environment that closely mimicked the temperature and oxygen concentration of synovial fluid. After 95 weeks of real-time aging, once-annealed components were oxidized; the melted components were not. The wear rate of the real-time aged irradiated and once-annealed components was higher than the literature reported values of other contemporary highly cross-linked UHMWPEs. Single annealing after irradiation used with terminal gamma sterilization may adversely affect the long-term oxidative stability of UHMWPE components.

Enhancement of mechanical properties of 3D printed hydroxyapatite by combined low and high molecular weight polycaprolactone sequential infiltration.

PubMed

Suwanprateeb, Jintamai; Thammarakcharoen, Faungchat; Hobang, Nattapat

2016-11-01

A new infiltration technique using a combination of low and high molecular weight polycaprolactone (PCL) in sequence was developed as a mean to improve the mechanical properties of three dimensional printed hydroxyapatite (HA). It was observed that using either high (M n ~80,000) or low (M n ~10,000) molecular weight infiltration could only increase the flexural modulus compared to non-infiltrated HA, but did not affect strength, strain at break and energy at break. In contrast, a combination of low and high molecular infiltration in sequence increased the flexural modulus, strength and energy at break compared to those of non-infiltrated HA or infiltrated by high or low molecular weight PCL alone. This overall enhancement was found to be attributed to the densification of low molecular weight PCL and the reinforcement of high molecular PCL concurrently. The combined low and high molecular weight infiltration in sequence also maintained high osteoblast proliferation and differentiation of the composites at the similar level of the HA. Densification was a dominant mechanism for the change in modulus with porosity and density of the infiltrated HA/PCL composites. However, both densification and the reinforcing performance of the infiltration phase were crucial for strength and toughening enhancement of the composites possibly by the defect healing and stress shielding mechanisms. The sequence of using low molecular weight infiltration and followed by high molecular infiltration was seen to provide the greatest flexural properties and highest cells proliferation and differentiation capabilities.

Origin of change in molecular-weight dependence for polymer surface tension.

PubMed

Thompson, R B; Macdonald, J R; Chen, P

2008-09-01

Self-consistent-field theory is used to reproduce the behavior of polymer surface tension with molecular-weight for both lower and higher molecular-weight polymers. The change in behavior of the surface tension between these two regimes is shown to be due to the almost total exclusion of polymer from the nonpolymer bulk phase. The predicted two regime surface tension behavior with molecular-weight and the exclusion explanation are shown to be valid for a range of different polymer compressibilities.

Rare expression of high-molecular-weight cytokeratin in adenocarcinoma of the prostate gland: a study of 100 cases of metastatic and locally advanced prostate cancer.

PubMed

Yang, X J; Lecksell, K; Gaudin, P; Epstein, J I

1999-02-01

Immunohistochemistry with antibodies for high-molecular-weight cytokeratin labels basal cells and is used as an ancillary study in diagnosing prostate carcinoma, which reportedly lacks expression of high-molecular-weight cytokeratin. A recent report questioned the specificity of this marker, describing immunopositivity for high-molecular-weight cytokeratin in a small series of metastatic prostate cancer. We have also noted rare cases of prostate lesions on biopsy with typical histological features of adenocarcinoma showing immunopositivity for high-molecular-weight cytokeratin, either in tumor cells or in patchy cells with the morphology of basal cells. In some of these cases, it was difficult to distinguish cancer from out-pouching of high-grade prostatic intraepithelial neoplasia. To investigate whether prostate cancer cells express high-molecular-weight cytokeratin, we studied 100 cases of metastatic prostate carcinoma and 10 cases of prostate cancer invading the seminal vesicles from surgical specimens. Metastatic sites included regional lymph nodes (n = 67), bone (n = 19), and miscellaneous (n = 14). Cases with any positivity for high-molecular-weight cytokeratin antibody (34betaE12) were verified as being of prostatic origin with immunohistochemistry for prostate-specific antigen and prostate-specific acid phosphatase. Only four cases were detected positive for high-molecular-weight cytokeratin. In two cases (one metastasis, one seminal vesicle invasion) there was weakly diffuse positivity above background level. Two metastases in lymph nodes showed scattered strong staining of clusters of tumor cells, which represented <0.2% of tumor cells in the metastatic deposits. These positive cells did not have the morphology of basal cells. We conclude that prostate cancer, even high grade, only rarely expresses high-molecular-weight cytokeratin. This marker remains a very useful adjunct in the diagnosis of prostate cancer.

High and low molecular weight hyaluronic acid differentially influence macrophage activation

PubMed Central

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

21 CFR 178.3750 - Polyethylene glycol (mean molecular weight 200-9,500).

Code of Federal Regulations, 2010 CFR

2010-04-01

... conditions: (a) The additive is an addition polymer of ethylene oxide and water with a mean molecular weight of 200 to 9,500. (b) It contains no more than 0.2 percent total by weight of ethylene and diethylene... ethylene and diethylene glycols if its mean molecular weight is below 350, when tested by the analytical...

[The high-molecular glutenins of the soft winter wheats from European countries and their relationship to the glutenin composition of the ancient and modern wheat varieties of Ukraine].

PubMed

Rabinovich, S V; Fedak, G; Lukov, O

2000-01-01

The sources of high-quality components of HMW glutenines determining grain quality, as initial material for breeding in the conditions of Ukraine were revealed on the base of analysis of 75 literature sources data about composition of high-molecular weight (HMW) glutenin and pedigrees of 598 European wheats from 12 countries, bred in 1923-1997, including, 449 cultivars from West and 149 East Europe. Origin of these components was observed in varieties of Great Britain, France and Germany from ancient Ukrainian wheat Red Fife and it derivative spring wheats of Canada--Marquis, Garnet, Regent, Saunders, Selkirk and of USA--spring wheat Thatcher and winter wheats--Kanred and Oro--as directly as via cultivars of European countries and Australia; in wheats of East European countries from winter wheats Myronivs'ka 808 and Bezostaya 1 (derivative of Ukrainian cultivars Ukrainka and Krymka) and their descendants; in wheats of Austria and Italy--from the both genetical sources.

Soy sauce and its umami taste: a link from the past to current situation.

PubMed

Lioe, Hanifah Nuryani; Selamat, Jinap; Yasuda, Masaaki

2010-04-01

Soy sauce taste has become a focus of umami taste research. Umami taste is a 5th basic taste, which is associated to a palatable and pleasurable taste of food. Soy sauce has been used as an umami seasoning since the ancient time in Asia. The complex fermentation process occurred to soy beans, as the raw material in the soy sauce production, gives a distinct delicious taste. The recent investigation on Japanese and Indonesian soy sauces revealed that this taste is primarily due to umami components which have molecular weights lower than 500 Da. Free amino acids are the low molecular compounds that have an important role to the taste, in the presence of sodium salt. The intense umami taste found in the soy sauces may also be a result from the interaction between umami components and other tastants. Small peptides are also present, but have very low, almost undetected umami taste intensities investigated in their fractions.

A novel Hsp70 inhibitor prevents cell intoxication with the actin ADP-ribosylating Clostridium perfringens iota toxin

PubMed Central

Ernst, Katharina; Liebscher, Markus; Mathea, Sebastian; Granzhan, Anton; Schmid, Johannes; Popoff, Michel R.; Ihmels, Heiko; Barth, Holger; Schiene-Fischer, Cordelia

2016-01-01

Hsp70 family proteins are folding helper proteins involved in a wide variety of cellular pathways. Members of this family interact with key factors in signal transduction, transcription, cell-cycle control, and stress response. Here, we developed the first Hsp70 low molecular weight inhibitor specifically targeting the peptide binding site of human Hsp70. After demonstrating that the inhibitor modulates the Hsp70 function in the cell, we used the inhibitor to show for the first time that the stress-inducible chaperone Hsp70 functions as molecular component for entry of a bacterial protein toxin into mammalian cells. Pharmacological inhibition of Hsp70 protected cells from intoxication with the binary actin ADP-ribosylating iota toxin from Clostridium perfringens, the prototype of a family of enterotoxins from pathogenic Clostridia and inhibited translocation of its enzyme component across cell membranes into the cytosol. This finding offers a starting point for novel therapeutic strategies against certain bacterial toxins. PMID:26839186

Effect of molecular weight of starch on the properties of cassava starch microspheres prepared in aqueous two-phase system.

PubMed

Xia, Huiping; Li, Bing-Zheng; Gao, Qunyu

2017-12-01

Starch microspheres (SMs) were fabricated in an aqueous two-phase system (ATPS). A series of starch samples with different molecular weight were prepared by acid hydrolysis, and the effect of molecular weight of starch on the fabrication of SMs were investigated. Scanning electron microscopy (SEM) showed that the morphologies of SMs varied with starch molecular weight, and spherical SMs with sharp contours were obtained while using starch samples with weight-average molecular weight (M¯w)≤1.057×10 5 g/mol. X-ray diffraction (XRD) results revealed that crystalline structure of SMs were different from that of native cassava starch, and the relative crystallinity of SMs increased with the molecular weight of starch decreasing. Differential scanning calorimetry (DSC) results showed peak gelatinization temperature (T p ) and enthalpy of gelatinization (ΔH) of SMs increased with decreased M¯wof starch. Stability tests indicated that the SMs were stable under acid environment, but not stable under α-amylase hydrolysis. Copyright © 2017. Published by Elsevier Ltd.

Molecular Design and Evaluation of Biodegradable Polymers Using a Statistical Approach

PubMed Central

Lewitus, Dan; Rios, Fabian; Rojas, Ramiro; Kohn, Joachim

2013-01-01

The challenging paradigm of bioresorbable polymers, whether in drug delivery or tissue engineering, states that a fine-tuning of the interplay between polymer properties (e.g., thermal, degradation), and the degree of cell/tissue replacement and remodeling is required. In this paper we describe how changes in the molecular architecture of a series of terpolymers allow for the design of polymers with varying glass transition temperatures and degradation rates. The effect of each component in the terpolymers is quantified via design of experiment (DoE) analysis. A linear relationship between terpolymer components and resulting Tg (ranging from 34 to 86 °C) was demonstrated. These findings were further supported with mass-per-flexible-bond (MPFB) analysis. The effect of terpolymer composition on the in vitro degradation of these polymers revealed molecular weight loss ranging from 20 to 60% within the first 24 hours. DoE modeling further illustrated the linear (but reciprocal) relationship between structure elements and degradation for these polymers. Thus, we describe a simple technique to provide insight into the structure property relationship of degradable polymers, specifically applied using a new family of tyrosine-derived polycarbonates, allowing for optimal design of materials for specific applications. PMID:23888354

A study on the quality control of slow burning polyester

NASA Astrophysics Data System (ADS)

Chen, Bin; Wang, Yinglei; Yan, Zhengfeng; Yu, Tao

2018-04-01

In this paper, the influence of the alcohol/acid mole ratio, reaction temperature, warm-up mode, end-capping, vacuity to the quality of slow burning polyester was studied. The hydroxyl value will increase when the alcohol/acid mole ratio increase, but the acid value and molecular weight will decrease. The molecular weight and molecular weight distribution of the polyester consistent with the designed one can be obtained by stepped heating up. Monobasic alcohol end-capping can be used to control the molecular weight effectively and reduce acid value. Stripping process narrow the molecular weight distribution and reduce the hydroxyl value. Decompression is in favor of the decrease of acid value and increase of the reaction speed to get qualified production.

Highly Conductive Ionic-Liquid Gels Prepared with Orthogonal Double Networks of a Low-Molecular-Weight Gelator and Cross-Linked Polymer.

PubMed

Kataoka, Toshikazu; Ishioka, Yumi; Mizuhata, Minoru; Minami, Hideto; Maruyama, Tatsuo

2015-10-21

We prepared a heterogeneous double-network (DN) ionogel containing a low-molecular-weight gelator network and a polymer network that can exhibit high ionic conductivity and high mechanical strength. An imidazolium-based ionic liquid was first gelated by the molecular self-assembly of a low-molecular-weight gelator (benzenetricarboxamide derivative), and methyl methacrylate was polymerized with a cross-linker to form a cross-linked poly(methyl methacrylate) (PMMA) network within the ionogel. Microscopic observation and calorimetric measurement revealed that the fibrous network of the low-molecular-weight gelator was maintained in the DN ionogel. The PMMA network strengthened the ionogel of the low-molecular-weight gelator and allowed us to handle the ionogel using tweezers. The orthogonal DNs produced ionogels with a broad range of storage elastic moduli. DN ionogels with low PMMA concentrations exhibited high ionic conductivity that was comparable to that of a neat ionic liquid. The present study demonstrates that the ionic conductivities of the DN and single-network, low-molecular-weight gelator or polymer ionogels strongly depended on their storage elastic moduli.

Rapid analysis of controlled substances using desorption electrospray ionization mass spectrometry.

PubMed

Rodriguez-Cruz, Sandra E

2006-01-01

The recently developed technique of desorption electrospray ionization (DESI) has been applied to the rapid analysis of controlled substances. Experiments have been performed using a commercial ThermoFinnigan LCQ Advantage MAX ion-trap mass spectrometer with limited modifications. Results from the ambient sampling of licit and illicit tablets demonstrate the ability of the DESI technique to detect the main active ingredient(s) or controlled substance(s), even in the presence of other higher-concentration components. Full-scan mass spectrometry data provide preliminary identification by molecular weight determination, while rapid analysis using the tandem mass spectrometry (MS/MS) mode provides fragmentation data which, when compared to the laboratory-generated ESI-MS/MS spectral library, provide structural information and final identification of the active ingredient(s). The consecutive analysis of tablets containing different active components indicates there is no cross-contamination or interference from tablet to tablet, demonstrating the reliability of the DESI technique for rapid sampling (one tablet/min or better). Active ingredients have been detected for tablets in which the active component represents less than 1% of the total tablet weight, demonstrating the sensitivity of the technique. The real-time sampling of cannabis plant material is also presented.

21 CFR 172.820 - Polyethylene glycol (mean molecular weight 200-9,500).

Code of Federal Regulations, 2011 CFR

2011-04-01

... the total ethylene and diethylene glycol content of polyethylene glycols having mean molecular weights... and diethylene glycol content of polyethylene glycols having mean molecular weights below 450. Analytical Method ethylene glycol and diethylene glycol content of polyethylene glycols The analytical method...

Effects of Hofmeister Anions on the LCST of PNIPAM as a Function of Molecular Weight

PubMed Central

Zhang, Yanjie; Furyk, Steven; Sagle, Laura B.; Cho, Younhee; Bergbreiter, David E.; Cremer, Paul S.

2008-01-01

The effect of a series of sodium salts on the lower critical solution temperature (LCST) of poly(N-isopropylacrylamide), PNIPAM, was investigated as a function of molecular weight and polymer concentration with a temperature gradient microfluidic device under a dark-field microscope. In solutions containing sufficient concentrations of kosmotropic anions, the phase transition of PNIPAM was resolved into two separate steps for higher molecular weight samples. The first step of this two step transition was found to be sensitive to the polymer’s molecular weight and solution concentration, while the second step was not. Moreover, the binding of chaotropic anions to the polymer was also influenced by molecular weight. Both sets of results could be explained by the formation of intramolecular and intermolecular hydrogen-bonding between polymer chains. By contrast, the hydrophobic hydration of the isopropyl moieties and polymer backbone was found to be unaffected by either the polymer’s molecular weight or solution concentration. PMID:18820735

Detection of Inulin, a Prebiotic Polysaccharide, in Maple Syrup.

PubMed

Sun, Jiadong; Ma, Hang; Seeram, Navindra P; Rowley, David C

2016-09-28

Maple syrup is a widely consumed plant-derived natural sweetener produced by concentrating xylem sap collected from certain maple (Acer) species. During thermal evaporation of water, natural phytochemical components are concentrated in maple syrup. The polymeric components from maple syrup were isolated by ethanol precipitation, dialysis, and anion exchange chromatography and structurally characterized by glycosyl composition analysis, glycosyl linkage analysis, and nuclear magnetic resonance spectroscopy. Among the maple syrup polysaccharides, one neutral polysaccharide was characterized as inulin with a broad molecular weight distribution, representing the first isolation of this prebiotic carbohydrate from a xylem sap. In addition, two acidic polysaccharides with structural similarity were identified as arabinogalactans derived from rhamnogalacturonan type I pectic polysaccharides.

Determination of partition coefficients of biomolecules in a microfluidic aqueous two phase system platform using fluorescence microscopy.

PubMed

Silva, D F C; Azevedo, A M; Fernandes, P; Chu, V; Conde, J P; Aires-Barros, M R

2017-03-03

Aqueous two phase systems (ATPS) offer great potential for selective separation of a wide range of biomolecules by exploring differences in molecular solubility in each of the two immiscible phases. However, ATPS use has been limited due to the difficulty in predicting the behavior of a given biomolecule in the partition environment together with the empirical and time-consuming techniques that are used for the determination of partition and extraction parameters. In this work, a fast and novel technique based on a microfluidic platform and using fluorescence microscopy was developed to determine the partition coefficients of biomolecules in different ATPS. This method consists of using a microfluidic device with a single microchannel and three inlets. In two of the inlets, solutions containing the ATPS forming components were loaded while the third inlet was fed with the FITC tagged biomolecule of interest prepared in milli-Q water. Using fluorescence microscopy, it was possible to follow the location of the FITC-tagged biomolecule and, by simply varying the pumping rates of the solutions, to quickly test a wide variety of ATPS compositions. The ATPS system is allowed 4min for stabilization and fluorescence micrographs are used to determine the partition coefficient.The partition coefficients obtained were shown to be consistent with results from macroscale ATPS partition. This process allows for faster screening of partition coefficients using only a few microliters of material for each ATPS composition and is amenable to automation. The partitioning behavior of several biomolecules with molecular weights (MW) ranging from 5.8 to 150kDa, and isoelectric points (pI) ranging from 4.7 to 6.4 was investigated, as well as the effect of the molecular weight of the polymer ATPS component. Copyright © 2016 Elsevier B.V. All rights reserved.

Fluid inclusions in quartz crystals from South-West Africa

USGS Publications Warehouse

Kvenvolden, K.A.; Roedder, E.

1971-01-01

Quartz crystals from calcite veins of unknown age in Precambrian metasedimentary rocks at Geiaus No. 6 and Aukam farms in South-West Africa contain both primary and secondary inclusions filled with one or a variable combination of: organic liquid, moderately saline aqueous liquid, dark-colored solid, and vapor. Analysis of these materials by microscopy and by gas chromatography and mass spectrometry shows the presence of constituents of both low and high molecular weights. The former include CH4, C2H6, C3H8 and possibly C4H10 as well as CO, CO2, H2O, N2 and H2. High molecular weight components are dominantly n-alkanes and isoprenoid hydrocarbons. The n-alkanes range from at least n-C10 to n-C33. Concentrations of n-alkanes larger than n-C17 decrease regularly with increasing carbon number. An homologous series of isoprenoid hydrocarbons ranging from at least C14 to C20 is present in unusually high concentrations. Pristane (C19) is most abundant, and C17 isoprenoid is least abundant. The molecular composition and distribution of hydrocarbons suggest biological precursors for these components. Consideration of data provided by freezing, crushing and heating experiments suggests that the pressures at the time these in part supercritical fluids were trapped probably exceeded 30-40 atm, and the minimum trapping temperature was about 120-160??C. Both primary and secondary inclusions apparently containing only organic materials were trapped by the growth of the host quartz from aqueous solution. The data obtained neither prove nor preclude Precambrian, Paleozoic or younger sources for the organic materials. ?? 1971.

Bufo arenarum egg jelly coat: purification and characterization of two highly glycosylated proteins.

PubMed Central

Arranz, S E; Albertali, I E; Cabada, M O

1997-01-01

Egg jelly coats from Bufo arenarum are formed by components secreted along the oviduct. These secretion products overlay the oocytes as they transit along the different oviductal portions. In this study, we have isolated two highly glycosylated proteins of the jelly coat, which are secreted almost all the way along the oviduct. Both glycoproteins [designated as highly glycosylated protein (HGP) and low-molecular-mass highly glycosylated protein (L-HGP)] were purified to homogeneity, from the secretion of the caudal oviduct portion, by CsCl density gradient ultracentrifugation. HGP is a high-molecular-mass protein with mucin-like characteristics: high viscosity, a high content of serine and threonine, about 70% carbohydrate by weight, and a protease-resistant domain. Cleavage of disulphide bridges with reducing agents resulted in the release of a single subunit (300000 Da). L-HGP is also a disulphide-cross-linked protein with lower apparent monomeric molecular mass, in the range 100-120 kDa and containing 50% carbohydrate by weight. HGP contains galactose, fucose, N-acetylgalactosamine and sialic acid, but no mannose, suggesting the presence of O-linked oligosaccharides exclusively. The secretion ratio of HGP increases from cephalic (16% of total protein in pars preconvoluta) to caudal (40% of total protein in pars convoluta) oviductal portions. It appears to be the major structural component of the jelly coat. Our purification data suggest that HGP is non-covalently linked to the other egg jelly proteins. Polyclonal antiserum to each purified glycoprotein from secretion was raised in rabbits and used to localize both glycoproteins in the different oviductal portions, total egg jelly and the aqueous medium where oocyte strings were incubated. HGP forms a stable fibre matrix around the oocyte. L-HGP is present in the jelly coat and is released into the incubation medium. PMID:9173897

Characterization of the Organic Component of Low-Molecular-Weight Chromium-Binding Substance and Its Binding of Chromium123

PubMed Central

Chen, Yuan; Watson, Heather M.; Gao, Junjie; Sinha, Sarmistha Halder; Cassady, Carolyn J.; Vincent, John B.

2011-01-01

Chromium was proposed to be an essential element over 50 y ago and was shown to have therapeutic potential in treating the symptoms of type 2 diabetes; however, its mechanism of action at a molecular level is unknown. One chromium-binding biomolecule, low-molecular weight chromium-binding substance (LMWCr or chromodulin), has been found to be biologically active in in vitro assays and proposed as a potential candidate for the in vivo biologically active form of chromium. Characterization of the organic component of LMWCr has proven difficult. Treating bovine LMWCr with trifluoroacetic acid followed by purification on a graphite powder micro-column generates a heptapeptide fragment of LMWCr. The peptide sequence of the fragment was analyzed by MS and tandem MS (MS/MS and MS/MS/MS) using collision-induced dissociation and post-source decay. Two candidate sequences, pEEEEGDD and pEEEGEDD (where pE is pyroglutamate), were identified from the MS/MS experiments; additional tandem MS suggests the sequence is pEEEEGDD. The N-terminal glutamate residues explain the inability to sequence LMWCr by the Edman method. Langmuir isotherms and Hill plots were used to analyze the binding constants of chromic ions to synthetic peptides similar in composition to apoLMWCr. The sequence pEEEEGDD was found to bind 4 chromic ions per peptide with nearly identical cooperativity and binding constants to those of apoLMWCr. This work should lead to further studies elucidating or eliminating a potential role for LMWCr in treating the symptoms of type 2 diabetes and other conditions resulting from improper carbohydrate and lipid metabolism. PMID:21593351

Hydrophobic organic contaminants in surficial sediments of Baltimore Harbor: Inventories and sources

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

Ashley, J.T.F.; Baker, J.E.

1999-05-01

The heavily urbanized and industrialized Baltimore Harbor/Patapsco River/Back River system is one of the most highly contaminated regions of the Chesapeake Bay. In June 1996, surficial sediments were collected at 80 sites throughout the subestuarine system, including historically undersampled creek sand embayments. The samples were analyzed for a suite of hydrophobic organic contaminants (HOCs) consisting of 32 polycyclic aromatic hydrocarbons (PAHs) and 113 polychlorinated biphenyl (PCB) congeners. Total PAH and total PCB concentrations ranged from 90 to 46,200 and 8 to 2,150 ng/g dry weight, respectively. There was enormous spatial variability in the concentrations of HOCs, which was not wellmore » correlated to grain size or organic carbon content, suggesting nonequilibrium partitioning and/or proximity to sources as important factors explaining the observed spatial variability. High concentrations of both classes of HOCs were localized around major urban stormwater runoff discharges. Elevated PAH concentrations were also centered around the Sparrow`s Point Industrial Complex, most likely a result of the pyrolysis of coal during the production of steel. All but 1 of the 80 sites exceeded the effects range-low (ERL) for total PCBs and, of those sites, 40% exceeded the effects range-medium (ERM), suggesting toxicity to marine benthic organisms would frequently occur. Using principal component analysis, differences in PAH signatures were discerned. Higher molecular weight PAHs were enriched in signatures from sediments close to suspected sources (i.e., urban stormwater runoff and steel production complexes) compared to those patterns observed at sites further from outfalls or runoff. Due to varying solubilities and affinities for organic matter of the individual PAHs, partitioning of the heavier weight PAHs may enrich settling particles with high molecular weight PAHs. Lower molecular weight PAHs, having lower affinity for particles, may travel from the source to a greater extent.« less

Molecular Weight Determination by an Improved Temperature-Monitored Vapor-Density Method.

ERIC Educational Resources Information Center

Grider, Douglas J.; And Others

1988-01-01

Recommends determining molecular weights of liquids by use of a thermocouple. Utilizing a mathematical gas equation, the molecular weight can be determined from the measurement of the vapor temperature upon complete evaporation. Lists benefits as reduced time and cost, and improved safety factors. (ML)

Factors that affect molecular weight distribution of Suwannee river fulvic acid as determined by electrospray ionization/mass spectrometry

USGS Publications Warehouse

Rostad, Colleen E.; Leenheer, Jerry A.

2004-01-01

Effects of methylation, molar response, multiple charging, solvents, and positive and negative ionization on molecular weight distributions of aquatic fulvic acid were investigated by electrospray ionization/mass spectrometry. After preliminary analysis by positive and negative modes, samples and mixtures of standards were derivatized by methylation to minimize ionization sites and reanalyzed.Positive ionization was less effective and produced more complex spectra than negative ionization. Ionization in methanol/water produced greater response than in acetonitrile/water. Molar response varied widely for the selected free acid standards when analyzed individually and in a mixture, but after methylation this range decreased. After methylation, the number average molecular weight of the Suwannee River fulvic acid remained the same while the weight average molecular weight decreased. These differences are probably indicative of disaggregation of large aggregated ions during methylation. Since the weight average molecular weight decreased, it is likely that aggregate formation in the fulvic acid was present prior to derivatization, rather than multiple charging in the mass spectra.

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

PubMed

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.

SEDFIT-MSTAR: Molecular weight and molecular weight distribution analysis of polymers by sedimentation equilibrium in the ultracentrifuge

PubMed Central

Schuck, Peter; Gillis, Richard B.; Besong, Tabot M.D.; Almutairi, Fahad; Adams, Gary G.; Rowe, Arthur J.; Harding, Stephen E.

2014-01-01

Sedimentation equilibrium (analytical ultracentrifugation) is one of the most inherently suitable methods for the determination of average molecular weights and molecular weight distributions of polymers, because of its absolute basis (no conformation assumptions) and inherent fractionation ability (without the need for columns or membranes and associated assumptions over inertness). With modern instrumentation it is also possible to run up to 21 samples simultaneously in a single run. Its application has been severely hampered because of difficulties in terms of baseline determination (incorporating estimation of the concentration at the air/solution meniscus) and complexity of the analysis procedures. We describe a new method for baseline determination based on a smart-smoothing principle and built into the highly popular platform SEDFIT for the analysis of the sedimentation behavior of natural and synthetic polymer materials. The SEDFIT-MSTAR procedure – which takes only a few minutes to perform - is tested with four synthetic data sets (including a significantly non-ideal system) a naturally occurring protein (human IgG1) and two naturally occurring carbohydrate polymers (pullulan and λ–carrageenan) in terms of (i) weight average molecular weight for the whole distribution of species in the sample (ii) the variation in “point” average molecular weight with local concentration in the ultracentrifuge cell and (iii) molecular weight distribution. PMID:24244936

Parasitoid wasp sting: a cocktail of GABA, taurine, and beta-alanine opens chloride channels for central synaptic block and transient paralysis of a cockroach host.

PubMed

Moore, Eugene L; Haspel, Gal; Libersat, Frederic; Adams, Michael E

2006-07-01

The wasp Ampulex compressa injects venom directly into the prothoracic ganglion of its cockroach host to induce a transient paralysis of the front legs. To identify the biochemical basis for this paralysis, we separated venom components according to molecular size and tested fractions for inhibition of synaptic transmission at the cockroach cercal-giant synapse. Only fractions in the low molecular weight range (<2 kDa) caused synaptic block. Dabsylation of venom components and analysis by HPLC and MALDI-TOF-MS revealed high levels of GABA (25 mM), and its receptor agonists beta-alanine (18 mM), and taurine (9 mM) in the active fractions. Each component produces transient block of synaptic transmission at the cercal-giant synapse and block of efferent motor output from the prothoracic ganglion, which mimics effects produced by injection of whole venom. Whole venom evokes picrotoxin-sensitive chloride currents in cockroach central neurons, consistent with a GABAergic action. Together these data demonstrate that Ampulex utilizes GABAergic chloride channel activation as a strategy for central synaptic block to induce transient and focal leg paralysis in its host. Copyright 2006 Wiley Periodicals, Inc.

Prediction of stream volatilization coefficients

USGS Publications Warehouse

Rathbun, Ronald E.

1990-01-01

Equations are developed for predicting the liquid-film and gas-film reference-substance parameters for quantifying volatilization of organic solutes from streams. Molecular weight and molecular-diffusion coefficients of the solute are used as correlating parameters. Equations for predicting molecular-diffusion coefficients of organic solutes in water and air are developed, with molecular weight and molal volume as parameters. Mean absolute errors of prediction for diffusion coefficients in water are 9.97% for the molecular-weight equation, 6.45% for the molal-volume equation. The mean absolute error for the diffusion coefficient in air is 5.79% for the molal-volume equation. Molecular weight is not a satisfactory correlating parameter for diffusion in air because two equations are necessary to describe the values in the data set. The best predictive equation for the liquid-film reference-substance parameter has a mean absolute error of 5.74%, with molal volume as the correlating parameter. The best equation for the gas-film parameter has a mean absolute error of 7.80%, with molecular weight as the correlating parameter.

Occurrence of a multimeric high-molecular-weight glyceraldehyde-3-phosphate dehydrogenase in human serum.

PubMed

Kunjithapatham, Rani; Geschwind, Jean-Francois; Devine, Lauren; Boronina, Tatiana N; O'Meally, Robert N; Cole, Robert N; Torbenson, Michael S; Ganapathy-Kanniappan, Shanmugasundaram

2015-04-03

Cellular glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a phylogenetically conserved, ubiquitous enzyme that plays an indispensable role in energy metabolism. Although a wealth of information is available on cellular GAPDH, there is a clear paucity of data on its extracellular counterpart (i.e., the secreted or extracellular GAPDH). Here, we show that the extracellular GAPDH in human serum is a multimeric, high-molecular-weight, yet glycolytically active enzyme. The high-molecular-weight multimers of serum GAPDH were identified by immunodetection on one- and two-dimensional gel electrophoresis using multiple antibodies specific for various epitopes of GAPDH. Partial purification of serum GAPDH by DEAE Affigel affinity/ion exchange chromatography further established the multimeric composition of serum GAPDH. In vitro data demonstrated that human cell lines secrete a multimeric, high-molecular-weight enzyme similar to that of serum GAPDH. Furthermore, LC-MS/MS analysis of extracellular GAPDH from human cell lines confirmed the presence of unique peptides of GAPDH in the high-molecular-weight subunits. Furthermore, data from pulse-chase experiments established the presence of high-molecular-weight subunits in the secreted, extracellular GAPDH. Taken together, our findings demonstrate the presence of a high-molecular-weight, enzymatically active secretory GAPDH in human serum that may have a hitherto unknown function in humans.

Ultrarapid electrophoretic transfer of high and low molecular weight proteins using heat.

PubMed

Kurien, Biji T; Scofield, R Hal

2009-01-01

An ultrarapid method for the electrophoretic transfer of high and low molecular weight proteins to nitrocellulose membranes following sodium dodecyl sulfate (SDS) polyacrylamide gel is described here. The transfer was performed with heated (70-75 degrees C) normal transfer buffer from which methanol had been omitted. Complete transfer of high and low molecular weight antigens (molecular weight protein standards, a purified protein, and proteins from a human tissue extract) could be carried out in 10 min for a 7% (0.75 mm) SDS polyacrylamide gel. For 10 and 12.5% gels (0.75 mm) the corresponding time was 15 min. A complete transfer could be carried out in 20 min for 7, 10, and 12.5% gels (1.5 mm gels). The permeability of the gel is increased by heat, such that the proteins trapped in the polyacrylamide gel matrix can be easily transferred to the membrane. The heat mediated transfer method was compared with a conventional transfer protocol, under similar conditions. The conventional method transferred minimal low molecular weight proteins while retaining most of the high molecular weight proteins in the gel. In summary, this procedure is particularly useful for the transfer of high molecular weight proteins, very rapid, and avoids the use of methanol.

Western blotting of high and low molecular weight proteins using heat.

PubMed

Kurien, Biji T; Scofield, R Hal

2015-01-01

A method for the electrophoretic transfer of high and low molecular weight proteins to nitrocellulose membranes following sodium dodecyl sulfate (SDS) polyacrylamide gel is described here. The transfer was performed with heated (70-75 °C) normal transfer buffer from which methanol had been omitted. Complete transfer of high and low molecular weight antigens (molecular weight protein standards, a purified protein, and proteins from a human tissue extract) could be carried out in 10 min for a 7 % (0.75 mm) SDS polyacrylamide gel. For 10 and 12.5 % gels (0.75 mm) the corresponding time was 15 min. A complete transfer could be carried out in 20 min for 7, 10, and 12.5 % gels (1.5 mm gels). The permeability of the gel is increased by heat, such that the proteins trapped in the polyacrylamide gel matrix can be easily transferred to the membrane. The heat mediated transfer method was compared with a conventional transfer protocol, under similar conditions. The conventional method transferred minimal low molecular weight proteins while retaining most of the high molecular weight proteins in the gel. In summary, this procedure is particularly useful for the transfer of high molecular weight proteins, very rapid, and avoids the use of methanol.

Hyaluronic Acid Molecular Weight-Dependent Modulation of Mucin Nanostructure for Potential Mucosal Therapeutic Applications.

PubMed

Hansen, Irene M; Ebbesen, Morten F; Kaspersen, Liselotte; Thomsen, Troels; Bienk, Konrad; Cai, Yunpeng; Malle, Birgitte Mølholm; Howard, Kenneth A

2017-07-03

This study investigates the effects of different molecular weight hyaluronic acids (HAs) on the mucosal nanostructure using a pig stomach mucin hydrogel as a mucosal barrier model. Microparticles (1.0 μm) and nanoparticles (200 nm) were used as probes, and their movement in mucin was studied by a three-dimensional confocal microscopy-based particle tracking technique and by Nanoparticle Tracking Analysis (NTA) after addition of high-molecular weight (900 kDa) and low-molecular weight (33 kDa) HA. This demonstrated a molecular weight-dependent HA modulation of the mucin nanostructure with a 2.5-fold decrease in the mobility of 200 nm nanoparticles. To further investigate these mechanisms and to verify that the natural viscoelastic properties of mucus are not undesirably altered, rheological measurements were performed on mucin hydrogels with or without HA. This suggested the observed particle mobility restriction was not attributed to alterations of the natural mucin cohesive and viscoelastic properties but, instead, indicates that the added high-molecular weight HA primarily modulates the mucin nanostructure and mesh size. This study, hereby, demonstrates how mucus nanostructure can be modulated by the addition of high-molecular weight HA that offers an opportunity to control mucosal pathogenesis and drug delivery.

Towards the optimal design of an uncemented acetabular component using genetic algorithms

NASA Astrophysics Data System (ADS)

Ghosh, Rajesh; Pratihar, Dilip Kumar; Gupta, Sanjay

2015-12-01

Aseptic loosening of the acetabular component (hemispherical socket of the pelvic bone) has been mainly attributed to bone resorption and excessive generation of wear particle debris. The aim of this study was to determine optimal design parameters for the acetabular component that would minimize bone resorption and volumetric wear. Three-dimensional finite element models of intact and implanted pelvises were developed using data from computed tomography scans. A multi-objective optimization problem was formulated and solved using a genetic algorithm. A combination of suitable implant material and corresponding set of optimal thicknesses of the component was obtained from the Pareto-optimal front of solutions. The ultra-high-molecular-weight polyethylene (UHMWPE) component generated considerably greater volumetric wear but lower bone density loss compared to carbon-fibre reinforced polyetheretherketone (CFR-PEEK) and ceramic. CFR-PEEK was located in the range between ceramic and UHMWPE. Although ceramic appeared to be a viable alternative to cobalt-chromium-molybdenum alloy, CFR-PEEK seems to be the most promising alternative material.

Multiple components in restriction enzyme digests of mammalian (insectivore), avian and reptilian genomic DNA hybridize with murine immunoglobulin VH probes.

PubMed

Litman, G W; Berger, L; Jahn, C L

1982-06-11

High molecular weight genomic DNAs isolated from an insectivore, Tupaia, and a representative reptilian, Caiman, and avian, Gallus, were digested with restriction endonucleases transferred to nitrocellulose and hybridized with nick-translated probes of murine VH genes. The derivations of the probes designated S107V (1) and mu 107V (2,3) have been described previously. Under conditions of reduced stringency, multiple hybridizing components were observed with Tupaia and Caiman; only mu mu 107V exhibited significant hybridization with the separated fragments of Gallus DNA. The nick-translated S107V probe was digested with Fnu4H1 and subinserts corresponding to the 5' and 3' regions both detected multiple hybridizing components in Tupaia and Caiman DNA. A 5' probe lacking the leader sequence identified the same components as the intact 5' probe, suggesting that VH coding regions distant as the reptilians may possess multiple genetic components which exhibit significant homology with murine immunoglobulin in VH regions.

Multiple components in restriction enzyme digests of mammalian (insectivore), avian and reptilian genomic DNA hybridize with murine immunoglobulin VH probes.

PubMed Central

Litman, G W; Berger, L; Jahn, C L

1982-01-01

High molecular weight genomic DNAs isolated from an insectivore, Tupaia, and a representative reptilian, Caiman, and avian, Gallus, were digested with restriction endonucleases transferred to nitrocellulose and hybridized with nick-translated probes of murine VH genes. The derivations of the probes designated S107V (1) and mu 107V (2,3) have been described previously. Under conditions of reduced stringency, multiple hybridizing components were observed with Tupaia and Caiman; only mu mu 107V exhibited significant hybridization with the separated fragments of Gallus DNA. The nick-translated S107V probe was digested with Fnu4H1 and subinserts corresponding to the 5' and 3' regions both detected multiple hybridizing components in Tupaia and Caiman DNA. A 5' probe lacking the leader sequence identified the same components as the intact 5' probe, suggesting that VH coding regions distant as the reptilians may possess multiple genetic components which exhibit significant homology with murine immunoglobulin in VH regions. Images PMID:6285298

[Structure and function of eukaryotic nuclear DNA-dependent RNA polymerase I].

PubMed

Shematorova, E K; Shpakovskiĭ, G V

2002-01-01

In the eukaryotic cell, normal protein biosynthesis is sustained by several million ribosomes, which contain rRNA as an essential component. The high-molecular-weight precursor of large and 5.8S rRNAs is synthesized by DNA-dependent RNA polymerase I (Pol I) in the nucleolus. Data on DNA regulatory elements, protein factors involved in rDNA transcription by Pol I, subunit composition of Pol I, and on the interactions and possible functions of individual subunits are summarized.

Mechanism of Lysergic Acid Diethylamide Interference with Rabbit Antibody Biosynthesis

PubMed Central

Voss, Edward W.; Winkelhake, Jeffrey L.

1974-01-01

Lymphoid cells from hyperimmune rabbits producing antibodies to a hapten, incubated in the presence of d-lysergic acid diethylamide, continued to synthesize protein at a normal rate. Isoelectric focusing analysis of the low-molecular-weight protein secreted by the cells incubated with lysergic acid diethylamide indicated two components, with pI's of 4.9 and 5.2. Immune cells not exposed to lysergic acid diethylamide secreted only 7S IgG molecules with an average pI of approximately 7.0. PMID:4524614

Synthesis of High Molecular Weight Fluoroalkylarylene-siloxanylene (FASIL) Polymer

DTIC Science & Technology

1979-01-01

impurity component" is shown in Figure 4. 6 When methyl(3,3,3-trifluoropropyl)diethoxysilane was added to the Grignard reagent at reflux instead of at...only a 34% yield. Inverse addi- tion, where the Grignard reagent was added to the diethoxysilane,gave a 43% yield. An impurity, ethoxymethyl(3,3,3...CH 2 CH2CF 3 Treatment of methyl(3,3,3-trifluoropropyl)dichlorosilane with excess ethanol gave methyl(3,3,3-trifluoropropyl)diethoxysilane. A Grignard

Heat collector

DOEpatents

Merrigan, M.A.

1981-06-29

A heat collector and method suitable for efficiently and cheaply collecting solar and other thermal energy are provided. The collector employs a heat pipe in a gravity-assist mode and is not evacuated. The collector has many advantages, some of which include ease of assembly, reduced structural stresses on the heat pipe enclosure, and a low total materials cost requirement. Natural convective forces drive the collector, which after startup operates entirely passively due in part to differences in molecular weights of gaseous components within the collector.

Heat collector

DOEpatents

Merrigan, Michael A.

1984-01-01

A heat collector and method suitable for efficiently and cheaply collecting solar and other thermal energy are provided. The collector employs a heat pipe in a gravity-assist mode and is not evacuated. The collector has many advantages, some of which include ease of assembly, reduced structural stresses on the heat pipe enclosure, and a low total materials cost requirement. Natural convective forces drive the collector, which after startup operates entirely passively due in part to differences in molecular weights of gaseous components within the collector.

Synthesis and characterization of the biodegradable and elastic terpolymer poly(glycolide-co-L-lactide-co-ϵ-caprolactone) for mechano-active tissue engineering.

PubMed

Jung, Youngmee; Lee, Sun-Hee; Kim, Sang-Heon; Lim, Jong Choo; Kim, Soo Hyun

2013-01-01

We synthesized a series of tri-component biodegradable copolymers with elastic characteristics by ring-opening copolymerization of cyclic lactones, that is, glycolide, L-lactide, and ϵ-caprolactone, in the presence of stannous octoate as a catalyst. We evaluated the physical and chemical characteristics of poly(glycolide-co-L-lactide-co-ϵ-caprolactone) (PGLCL) copolymers. The synthesized PGLCL had a high molecular weight of about 100 kD and an amorphous structure. It was confirmed that the physical and chemical properties of these terpolymers could be modulated by adjusting copolymer composition. PGLCL films exhibited rubber-like elasticity and showed almost complete recovery when subjected to 50% of the tensile strain. To examine the biodegradability of the PGLCL copolymers, we performed in vitro degradation tests for 12 weeks and observed changes in molecular weight, gross weight, and composition. These results showed that the glycolide was degraded most quickly and that ϵ-caprolactone was the slowest to degrade. Additionally, cytotoxicity tests revealed that none of the polymers were toxic. In summary, the mechanical properties and biodegradability of PGLCL terpolymers could be controlled by changing the monomer content, which may be useful for a wide range of tissue engineering applications based on mechanical property requirements.

Infrared Spectroscopy of Bilberry Extract Water-in-Oil Emulsions: Sensing the Water-Oil Interface

PubMed Central

Kiefer, Johannes; Frank, Kerstin; Zehentbauer, Florian M.; Schuchmann, Heike P.

2016-01-01

Water-in-oil (w/o) emulsions are of great interest in many areas of the life sciences, including food technology, bioprocess engineering, and pharmaceuticals. Such emulsions are complex multi-component systems and the molecular mechanisms which lead to a stable emulsion are yet to be fully understood. In this work, attenuated total reflection (ATR) infrared (IR) spectroscopy is applied to a series of w/o emulsions of an aqueous anthocyanin-rich bilberry extract dispersed in a medium chain triglyceride (MCT) oil phase. The content of the emulsifier polyglycerin-polyricinoleat (PGPR) has been varied systematically in order to investigate whether or not its concentration has an impact on the molecular stabilization mechanisms. The molecular stabilization is accessed by a careful analysis of the IR spectrum, where changes in the vibrational frequencies and signal strengths indicate alterations of the molecular environment at the water/oil interface. The results suggest that adding emulsifier in excess of 1% by weight does not lead to an enhanced stabilization of the emulsion. PMID:27089376

Photochemical behavior of dissolved and colloidal organic matter in estuarine and oceanic waters.

PubMed

Zhu, Wen-Zhuo; Yang, Gui-Peng; Zhang, Hong-Hai

2017-12-31

Chromophoric dissolved organic matter (CDOM), carbohydrates, and amino acids were analyzed to investigate the photochemistry of total dissolved (<0.22μm) organic matter (DOM), high-molecular-weight (HMW, 1kDa-0.22μm) DOM and low-molecular-weight (LMW, <1kDa) DOM at stations in the Yangtze River and its coastal area, and in the Western Pacific Ocean. Results revealed that the humic-like and tryptophan-like CDOM fluorescent components in riverine, coastal, and oceanic surface waters were photodegraded during irradiation. However, the photochemical behavior of tyrosine-like component was obscured by the excessive fluorescence intensities of humic- and tryptophan-like fluorescent components. Light sensitivity varied depending on the source material; terrestrially derived DOM was more susceptible to irradiation than autochthonous DOM. In contrast to the expected photodegradation of CDOM, photo-induced synthetic reaction transformed the LMW matters to polysaccharides (PCHO) and degradation reaction decomposed the HMW DOM to Monosaccharides. Colloidal DOM preferentially underwent photodegradation, whereas permeate DOM mainly photosynthesized PCHO. The total hydrolysable amino acid (THAA) pool changed because of the additional input by the photodegradation of DOM or THAA itself. The compositions of THAA changed during the irradiation experiments, indicating that the different photochemical behavior of individual amino acids were related to their different original photoreactivities; the relatively stable amino acids (e.g., Ser and Gly) significantly accumulated during irradiation, whereas photo-active aromatic amino acids (e.g. Tyr and His) were prone to photodegradation. The data presented here demonstrated that irradiation significantly influence the conversion between dissolved and colloid organic matter. These results can promote the understanding of irradiation effect on the carbon and nitrogen cycle in riverine, estuarine and oceanic ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

Properties of crosslinked ultra-high-molecular-weight polyethylene.

PubMed

Lewis, G

2001-02-01

Substantially reducing the rate of generation of wear particles at the surfaces of ultra-high-molecular-weight polyethylene (UHMWPE) orthopedic implant bearing components, in vivo, is widely regarded as one of the most formidable challenges in modern arthroplasty. In the light of this, much research attention has been paid to the myriad of endogenous and exogenous factors that have been postulated to affect this wear rate, one such factor being the polymer itself. In recent years, there has been a resurgence of interest in crosslinking the polymer as a way of improving its properties that are considered relevant to its use for fabricating bearing components. Such properties include wear resistance, fatigue life, and fatigue crack propagation rate. Although a large volume of literature exists on the topic on the impact of crosslinking on the properties of UHMWPE, no critical appraisal of this literature has been published. This is one of the goals of the present article, which emphasizes three aspects. The first is the trade-off between improvement in wear resistance and depreciation in other mechanical and physical properties. The second aspect is the presentation of a method of estimating the optimal value of a crosslinking process variable (such as dose in radiation-induced crosslinking) that takes into account this trade-off. The third aspect is the description of a collection of under- and unexplored research areas in the field of crosslinked UHMWPE, such as the role of starting resin on the properties of the crosslinked polymer, and the in vitro evaluation of the wear rate of crosslinked tibial inserts and other bearing components that, in vivo, are subjected to nearly unidirectional motion.

Electrophoretic and serological analyses of cytoplasmic antigens from Aspergillus fumigatus during growth of conidia to mature mycelia.

PubMed

Piechura, J E; Riefel, R S; Daft, L J

1987-08-01

The changes of cytoplasmic components concomitant with conidium to mature mycelium growth of Aspergillus fumigatus strain Ag 507 were analysed by one- and two-dimensional polyacrylamide gel electrophoresis (SDS-PAGE; 2-DE). SDS-PAGE monitored molecular weight differences between components of cytosol preparations obtained from conidia and those through 96 h of mycelial growth. 2-DE analyses indicated that some components characteristic of mature cytosol begin to appear by 7 h. Cytoplasmic preparations absorbed with rabbit immunoglobulins raised to mature cytosol were analysed by 2-DE. Conidia cytosol components were not absorbed to a great degree, unlike those from later stages of mycelial growth, which indicates that cytosol components may be changed and/or synthesized de novo during growth of the fungus. Analysis of the cytosol preparations by fused rocket immunoelectrophoresis showed that some components are synthesized in different amounts at various times during growth: 3, 4, 7, 8, and 18 h of growth, components begin to appear that may be synthesized de novo. Enzyme-linked immunosorbent assay with rabbit antiserum to mature cytosol and cytosol preparations obtained from conidia through 96 h of growth, indicated differences of molecular structures between the cytosol preparations. The anticytosol IgG and IgE titers of sera from patients with allergic bronchopulmonary aspergillosis were both elevated and fluctuated with each preparation. The specific IgG and IgE titers both appeared to be elevated with cytosol preparations obtained from 4, 5, 7, and 9 h of growth and highest against the 96 h preparation.

An evaluation of the effects of PEO/PEG molecular weights on extruded alumina rods

NASA Astrophysics Data System (ADS)

Bolger, Nancy Beth

1998-12-01

Alumina rods were piston extruded from bodies containing polyethylene glycols (PEGs) and polyethylene oxides (PEOs) with molecular weights ranging from 1,300 to 3,800,000 g/mol. A blend of aluminas possessing different particle size distributions was evaluated with regard to its extrusion pressure by varying the amount of PEG/PEO addition. Behavior exhibited by the alumina blend was dependent upon the additive that was used. The higher molecular weight binders with average molecular weight of 200,000 g/mol and 3,350,000 g/mol displayed the most severe behaviors of near dilatant and dilatant respectively. Physical properties of the green and fired states, as well as the binder burnout, were investigated with the changing additions. Correlation between the green and fired strengths and the changing molecular weights were examined. The additive present influenced the surface properties of the rods, which affected the green strengths. The highest average molecular weight polyethylene glycols showed higher green strengths, while the lowest green strengths were observed for the high molecular weight polyethylene oxides. Fired strengths generally ranged from approximately 12,000 psi to 16,000 psi for additive batches. Alumina pellets containing twelve separate combinations of polyethylene glycol with polyethylene oxide were dry pressed. Physical properties of the green and fired states were examined. Statistical analysis was performed upon the data and seven combinations of polyethylene glycol with polyethylene oxide were deemed significant. These combinations in conjunction with the same alumina blend were then piston extruded. The addition of polyethylene glycol reduced the near dilatant behavior exhibited by the 200,000 g/mol average molecular weight polyethylene oxide. Dilatant behavior was completely eliminated from the 3,350,000 g/mol average molecular weight polyethylene oxide batches. Physical properties of the green and fired states were again investigated with the changing additions. Polyethylene oxide, in combination with polyethylene glycol, did show an increase in green strength versus the polyethylene oxide alone. Strengths were still lower than those displayed by the polyethylene glycols alone. Reductions or degradations in molecular weight of the polymers due to mixing and extrusion processes may account for lower green strength of bodies, especially those containing polyethylene oxides.

Antimicrobial Polymers Prepared by ROMP with Unprecedented Selectivity: A Molecular Construction Kit Approach

PubMed Central

Lienkamp, Karen; Madkour, Ahmad E.; Musante, Ashlan; Nelson, Christopher F.; Nüsslein, Klaus

2014-01-01

Synthetic Mimics of Antimicrobial Peptides (SMAMPs) imitate natural host-defense peptides, a vital component of the body’s immune system. This work presents a molecular construction kit that allows the easy and versatile synthesis of a broad variety of facially amphiphilic oxanorbornene-derived monomers. Their ring-opening metathesis polymerization (ROMP) and deprotection provide several series of SMAMPs. Using amphiphilicity, monomer feed ratio, and molecular weight as parameters, polymers with 533 times higher selectivitiy (selecitviy = hemolytic concentration/minimum inhibitory concentration) for bacteria over mammalian cells were discovered. Some of these polymers were 50 times more selective for Gram-positive over Gram-negative bacteria while other polymers surprisingly showed the opposite preference. This kind of “double selectivity” (bacteria over mammalian and one bacterial type over another) is unprecedented in other polymer systems and is attributed to the monomer’s facial amphiphilicity. PMID:18593128

Determination of molecular diffusion coefficient in n-alkane binary mixtures: empirical correlations.

PubMed

De Mezquia, D Alonso; Bou-Ali, M Mounir; Larrañaga, M; Madariaga, J A; Santamaría, C

2012-03-08

In this work we have measured the molecular diffusion coefficient of the n-alkane binary series nC(i)-nC(6), nC(i)-nC(10), and nC(i)-nC(12) at 298 K and 1 atm and a mass fraction of 0.5 by using the so-called sliding symmetric tubes technique. The results show that the diffusion coefficient at this concentration is proportional to the inverse viscosity of the mixture. In addition, we have also measured the diffusion coefficient of the systems nC(12)-nC(6), nC(12)-nC(7), and nC(12)-nC(8) as a function of concentration. From the data obtained, it is shown that the diffusion coefficient of the n-alkane binary mixtures at any concentration can be calculated from the molecular weight of the components and the dynamic viscosity of the corresponding mixture at 50% mass fraction.

Functional Groups and Structural Insights of Water-Soluble Organic Carbon using Ultrahigh Resolution FT-ICR Tandem Mass Spectrometry

NASA Astrophysics Data System (ADS)

Mazzoleni, L. R.; Habib, D.; Zhao, Y.; Dalbec, M.; Samburova, V.; Hallar, G.; Zielinska, B.; Lowenthal, D.

2013-12-01

Water-soluble organic carbon (WSOC) is a complex mixture of thousands of organic compounds which may have significant influence on the climate-relevant properties of atmospheric aerosols. An improved understanding of the molecular composition of WSOC is needed to evaluate the effect of aerosol composition upon aerosol physical properties. Products of gas phase, aqueous phase and particle phase reactions contribute to pre-existing aerosol organic mass or nucleate new aerosol particles. Thus, ambient aerosols carry a complex array of WSOC components with variable chemical signatures depending upon its origin and aerosol life-cycle processes. In this work, ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to characterize aerosol WSOC collected during the summer of 2010 at the Storm Peak Laboratory (3210 m a.s.l.) near Steamboat Springs, CO. Approximately 4000 molecular formulas were assigned in the mass range of m/z 100-800 after negative-ion electrospray ionization. The observed trends indicate significant non-oxidative accretion reaction pathways for the formation of high molecular weight WSOC components closely associated with terpene ozonolysis secondary organic aerosol (SOA). The aerosol WSOC was further characterized using ultrahigh resolution tandem MS analysis with infrared multiphoton dissociation to determine the functional groups and structural properties of 1700 WSOC species up to m/z 600. Due to the complex nature of the WSOC, multiple precursor ions were simultaneously fragmented. The exact mass measurements of the precursor and product ions facilitated molecular formula assignments and matching of neutral losses. The most important neutral losses are CO2, H2O, CH3OH, HNO3, CH3NO3, SO3 and SO4. The presence and frequency of these losses indicate the type of functional groups contained in the precursor structures. Consistent with the acidic nature of WSOC compounds, the most frequently observed losses were CO2 (~65%), H2O (~60%) and CH3OH (~40%). Several of the studied precursors had two or more losses associated with them and combinations of neutral losses such as, H4O2, CH2O3, C2H4O3 and C2O4. These neutral losses clearly indicate a multifunctional nature of the studied aerosol WSOC. Analysis of the fragment ions which were not associated with typical neutral losses indicates an overall aliphatic SOA-like structure with regular differences of 14 Da and 18 Da between low molecular weight fragment ions. Many of the fragment ions were observed in 85% or more of the MS2 spectra. The patterns observed in the low molecular weight fragment ions were very consistent over all of the mass spectra providing evidence for the significance of the non-oxidative accretion formation pathways.

Thermo-acoustical molecular interaction study in binary mixtures of glycerol and ethylene glycol

NASA Astrophysics Data System (ADS)

Kaur, Kirandeep; Juglan, K. C.; Kumar, Harsh

2017-07-01

Ultrasonic velocity, density and viscosity are measured over the entire composition range for binary liquid mixtures of glycerol (CH2OH-CHOH-CH2OH) and ethylene glycol (HOCH2CH2OH) at different temperatures and constant frequency of 2MHz using ultrasonic interferometer, specific gravity bottle and viscometer respectively. Measured experimental values are used to obtained various acoustical parameters such as adiabatic compressibility, acoustic impedance, intermolecular free length, relaxation time, ultrasonic attenuation, effective molar weight, free volume, available volume, molar volume, Wada's constant, Rao's constant, Vander Waal's constant, internal pressure, Gibb's free energy and enthalpy. The variation in acoustical parameters are interpreted in terms of molecular interactions between the components of molecules of binary liquid mixtures.

Branched chain amino acids maintain the molecular weight of poly(γ-glutamic acid) of Bacillus licheniformis ATCC 9945 during the fermentation.

PubMed

Mitsunaga, Hitoshi; Meissner, Lena; Büchs, Jochen; Fukusaki, Eiichiro

2016-10-01

Poly(γ-glutamic acid) mainly produced by Bacillus spp. is an industrially important compound due to several useful features. Among them, molecular weight is an important characteristic affecting on the physical properties such as viscosities and negative charge densities. However, it is difficult to control the molecular size of PGA since it decreases during fermentation. Previous study reported that PGA produced in the media containing different carbon sources such as glucose and glycerol showed differences in molecular weight. Therefore in this study, the effect of carbon source on the PGA molecular weight was examined; with the aim of developing a strategy to maintain the high molecular weight of PGA during fermentation. Our result showed that the weight average molecular weight (Mw) of PGA of Bacillus licheniformis ATCC 9945 cultivated in the media containing PTS-sugars were higher than the medium containing glycerol (non-PTS). The result of metabolome analysis indicated the possibility of CodY (a global regulator protein) activation in the cells cultivated in the media containing PTS-sugars. To mimic this effect, branched-chain amino acids (BCAAs), which are activators of CodY, were added to a medium containing glycerol. As the result, the Mw of PGA in the BCAAs-supplemented media were maintained and high during the early production phase compared to the non BCAAs-supplemented medium. These results indicate that BCAAs can repress the PGA molecular weight reduction during fermentation in B. licheniformis ATCC 9945. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Long-term low-molecular-weight heparin and the post-thrombotic syndrome: a systematic review.

PubMed

Hull, Russell D; Liang, Jane; Townshend, Grace

2011-08-01

Post-thrombotic syndrome causes considerable morbidity. The Home-LITE study showed a lower incidence of post-thrombotic syndrome and venous ulcers after 3 months of treating deep vein thrombosis with the low-molecular-weight heparin tinzaparin versus oral anticoagulation. This systematic review examined whether long-term treatment of deep vein thrombosis using low-molecular-weight heparin, rather than oral anticoagulation, reduces development of post-thrombotic syndrome. We identified 9 articles comparing treatment of deep vein thrombosis using long-term low-molecular-weight heparin with any comparator, which reported outcomes relevant to the post-thrombotic syndrome assessed ≥ 3 months post-deep vein thrombosis. Pooled analysis of 2 studies yielded an 87% risk reduction with low-molecular-weight heparin in the incidence of venous ulcers at ≥ 3 months (P = .019). One study showed an overall odds ratio of 0.77 (P = .001) favoring low-molecular-weight heparin for the presence of 8 patient-reported post-thrombotic syndrome signs and symptoms. Pooled analysis of 5 studies showed a risk ratio for low-molecular-weight heparin versus oral anticoagulation of 0.66 (P < .0001) for complete recanalization of thrombosed veins. These results support the lower incidence of post-thrombotic syndrome and venous ulcers observed in Home-LITE. Long-term treatment with low-molecular-weight heparin rather than oral anticoagulation after a deep vein thrombosis may reduce or prevent development of signs and symptoms associated with post-thrombotic syndrome. Post-thrombotic syndrome and associated acute ulcers may develop more rapidly after deep vein thrombosis than previously recognized. Copyright © 2011 Elsevier Inc. All rights reserved.

Air-to-sea fluxes of lipids at Enewetak Atoll

NASA Astrophysics Data System (ADS)

Zafiriou, Oliver C.; Gagosian, Robert B.; Peltzer, Edward T.; Alford, Jane B.; Loder, T.

1985-02-01

We report data for the Enewetak site of the SEAREX program from the rainy season in 1979. The concentrations of n-alkanes, n-alkanols, sterols, n-alkanoic acids and their salts, and total organic compounds in rain are reported, as well as the apparent gaseous hydrocarbon concentrations. These data and information on the particulate forms are analyzed in conjunction with ancillary chemical and meteorological data to draw inferences about sources, fluxes, and chemical speciations. While the higher molecular weight lipid biomarker components are exclusively terrestrial, the organic carbon in rain may be derived from atmospheric transformations of terrestrial carbon. Distinctively marine components are nearly absent. Comparison of the scavenging ratios of the organic components in rain vs. those for clays reveals that the alkanoic acids and the higher molecular weight alkanols behave as essentially particulate materials, whereas lower alkanols and most hydrocarbons show much higher scavenging ratios, probably due to the involvement of a gaseous phase or sampling artifact. Vaporization in the atmosphere and scavenging of a gas phase would lead to higher scavenging ratios; vaporization during sampling would give low aerosol concentrations and high gas-phase concentrations, leading to high scavenging ratios. The major fluxes at Enewetak result from rain rather than dry deposition, and extrapolating the measured values to meaningful annual averages requires adjustment for seasonally varying source intensity and rain dynamics. Aerosol data for other seasons and other substances are used to correct for source-strength intensity variations, and a 210Pb/organic compound correlation is established and extrapolated to adjust for rainfall volume effects. These corrections, assumed independent and applied together, yield inferred fluxes 2.5-9 times larger than the fluxes calculated for mean concentrations. The inferred fluxes to the ocean, while small compared to primary production, are large enough to have potential impacts in the cycle of dissolved organic carbon and the sedimentary geochemistry of refractory lipid components.

A Simple, Inexpensive Molecular Weight Measurement for Water-Soluble Polymers Using Microemulsions.

ERIC Educational Resources Information Center

Mathias, Lon J.; Moore, D. Roger

1985-01-01

Describes an experiment involving use of a microemulsion and its characteristic thermal phase change to determine molecular weights of polyoxyethylene samples. The experiment provides students with background information on polymers and organized media and with experience in evaluating polymer molecular weight by using a unique property of a…

Determinations of molecular weight and molecular weight distribution of high polymers by the rheological properties

NASA Technical Reports Server (NTRS)

Huang, J. Y.; Hou, T. H.; Tiwari, S. N.

1989-01-01

Several methods are reviewed by which the molecular weight (MW) and the molecular weight distribution (MWD) of polymeric material were determined from the rheological properties. A poly(arylene ether) polymer with six different molecular weights was used in this investigation. Experimentally measured MW and MWD were conducted by GPC/LALLS (gel permeation chromatography/low angle laser light scattering), and the rheological properties of the melts were measured by a Rheometric System Four rheometer. It was found that qualitative information of the MW and MWD of these polymers could be derived from the viscoelastic properties, with the methods proposed by Zeichner and Patel, and by Dormier et al., by shifting the master curves of the dynamic storage modulus, G', and the loss modulus, G'', along the frequency axis. Efforts were also made to calculate quantitative profiles of MW and MWD for these polymers from their rheological properties. The technique recently proposed by Wu was evaluated. It was found that satisfactory results could only be obtained for polymers with single modal distribution in the molecular weight.

Ultrafiltration for the Determination of Cu Complexed with Dissolved Organic Matters of Different Molecular Weight from a Eutrophic River, China.

PubMed

Li, Anding; Zhang, Yan; Zhou, Beihai; Xin, Kailing; Gu, Yingnan; Xu, Weijie; Tian, Jie

2018-05-21

The molecular weight of dissolved organic matter (DOM) is one of the essential factors controlling the properties of metal complexes. A continuous ultrafiltration experiment was designed to study the properties of Cu complexes with different molecular weights in a river before and after eutrophication. The results showed that the concentration of DOM increased from 26.47 to 38.20 mg/L during the eutrophication process, however, DOM was still dominated by the small molecular weight fraction before and after eutrophication. The amount of Cu-DOM complexes increased with the increasing of molecular weight, however, the amounts of DOM-Cu complexes before eutrophication were higher than those after eutrophication. This is because DOM contained more -COOH and -OH before eutrophication and these functional groups are the active sites complexed with Cu.

Enrichment of low-molecular-weight proteins from biofluids for biomarker discovery.

PubMed

Chertov, Oleg; Simpson, John T; Biragyn, Arya; Conrads, Thomas P; Veenstra, Timothy D; Fisher, Robert J

2005-01-01

The dramatic progress in mass spectrometry-based methods of protein identification has triggered a new quest for disease-associated biomarkers. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and its variant surface-enhanced laser desorption/ionization mass spectrometry, provide effective means to explore the less studied information slice of the human serum proteome -- low-molecular-weight proteins and peptides. These low-molecular-weight proteins and peptides are promising for the detection of important biomarkers. Due to the significant experimental problems imposed by high-abundance and high-molecular-weight proteins, it is important to effectively remove these species prior to mass spectrometry analysis of the low-molecular-weight serum and plasma proteomes. In this review, the advantages afforded by recently introduced methods for prefractionation of serum, as they pertain to the detection and identification of biomarkers, will be discussed.

EPDM polymers with intermolecular asymmetrical molecular weight, crystallinity and diene distribution

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

Datta, S.; Cheremishinoff, N.P.; Kresge, E.N.

1993-12-31

Rapid extrusion of EPDM elastomers require low viscosity and thus low molecular weights for the polymer. Efficient vulcanization of these elastomers requires network perfection and thus high molecular weights for the polymer. The benefits of these apparently mutually exclusive goals is important in uses of EPDM elastomers which require extrusion of profiles which are later cured. This paper shows that by introducing simultaneously asymmetry in the distribution of molecular weights, crystallinity and vulcanizable sites these apparently contradictory goals can be resolved. While these polymers cannot be made from a single Ziegler polymerization catalyst, the authors show the synthesis of thesemore » model EPDM polymers by blending polymers with very different molecular weights, ethylene and ENB contents. These blends can be rapidly extruded without melt fracture and can be cured to vulcanizates which have excellent tensile properties.« less

Adsorption of dissolved organics in lake water by aluminum oxide. Effect of molecular weight

USGS Publications Warehouse

Davis, J.A.; Gloor, R.

1981-01-01

Dissolved organic compounds in a Swiss lake were fractionated into three molecular size classes by gel exclusion chromatography, and adsorption of each fraction on colloidal alumina was studied as a function of pH. Organic compounds with molecular weight (Mr) greater than 1000 formed strong complexes with the alumina surface, but low molecular weight compounds were weakly adsorbed. Electrophoretic mobility measurements indicated that alumina particles suspended in the original lake water were highly negatively charged because of adsorbed organic matter. Most of the adsorbed organic compounds were in the Mr range 1000 < Mr < 3000. Adsorption of these compounds during the treatment of drinking water by alum coagulation may be responsible for the preferential removal of trihalomethane precursors. Adsorption may also influence the molecular-weight distribution of dissolved organic material in lakes. surface, the present work will focus on the influence of molecular size and pH on the adsorption behavior of dissolved organic material of a Swiss lake. From a geochemical point of view, it is important to know the molecular-weight distribution of adsorbed organic matter so that we may better assess its reactivity with trace elements. The study also serves as a first step in quantifying the role of adsorption in the geochemical cycle of organic carbon in lacustrine environments. For water-treatment practice, we need to determine whether molecular weight fractionation occurs during adsorption by aluminum oxide. Such a fractionation could be significant in the light of recent reports that chloroform and other organochlorine compounds are preferentially produced by particular molecular-weight fractions (25-27). ?? 1981 American Chemical Society.

Effect of varying molecular weight of dextran on acrylic-derivatized dextran and concanavalin A glucose-responsive materials for closed-loop insulin delivery.

PubMed

Sahota, Tarsem; Sawicka, Kirsty; Taylor, Joan; Tanna, Sangeeta

2011-03-01

Dextran methacrylate (dex-MA) and concanavalin A (con A)-methacrylamide were photopolymerized to produce covalently cross-linked glucose-sensitive gels for the basis of an implantable closed-loop insulin delivery device. The viscoelastic properties of these polymerized gels were tested rheologically in the non-destructive oscillatory mode within the linear viscoelastic range at glucose concentrations between 0 and 5% (w/w). For each cross-linked gel, as the glucose concentration was raised, a decrease in storage modulus, loss modulus and complex viscosity (compared at 1 Hz) was observed, indicating that these materials were glucose responsive. The higher molecular weight acrylic-derivatized dextrans [degree of substitution (DS) 3 and 8%] produced higher complex viscosities across the glucose concentration range. These studies coupled with in vitro diffusion experiments show that dex-MA of 70 kDa and DS (3%) was the optimum mass average molar mass to produce gels that show reduced component leach, glucose responsiveness, and insulin transport useful as part of a self-regulating insulin delivery device.

Mapping of low molecular weight heparins using reversed phase ion pair liquid chromatography-mass spectrometry.

PubMed

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.

Isolation and structural characterisation of acid- and pepsin-soluble collagen from the skin of squid Sepioteuthis lessoniana (Lesson, 1830).

PubMed

Ramasamy, Pasiyappazham; Subhapradha, Namasivayam; Shanmugam, Vairamani; Shanmugam, Annaian

2014-01-01

Acid-solubilised collagen (ASC) and pepsin-solubilised collagen (PSC) were effectively isolated from squid skin with good yield and total protein content. ASC and PSC consist of two α-chains with an imino acid content of 182.6 and 184 imino acid residues/1000 residues. The molecular weight was determined to be between 73 and 107 kDa by using SDS-PAGE. For peptide mapping, collagens were digested with achromo endopeptidase, and all components, including α, β-chains, were markedly hydrolysed. Degradation peptides with molecular weights between 106.9 and 15.47 kDa were obtained. UV-vis absorption spectrum revealed distinct absorption at 220-240 nm. FT-IR spectra of collagens were almost similar when compared with standard. In differential scanning calorimetry profile, ASC and PSC exhibited a To of 59.10, 62.18°C and TP of 104.91, 98.10 °C, respectively. This investigation indicates that the collagen isolated from the squid skin, which is thrown as waste in the seafood-processing plant, might supplement the vertebrate collagen in industrial applications.

Polymer therapeutics: concepts and applications.

PubMed

Haag, Rainer; Kratz, Felix

2006-02-13

Polymer therapeutics encompass polymer-protein conjugates, drug-polymer conjugates, and supramolecular drug-delivery systems. Numerous polymer-protein conjugates with improved stability and pharmacokinetic properties have been developed, for example, by anchoring enzymes or biologically relevant proteins to polyethylene glycol components (PEGylation). Several polymer-protein conjugates have received market approval, for example the PEGylated form of adenosine deaminase. Coupling low-molecular-weight anticancer drugs to high-molecular-weight polymers through a cleavable linker is an effective method for improving the therapeutic index of clinically established agents, and the first candidates have been evaluated in clinical trials, including, N-(2-hydroxypropyl)methacrylamide conjugates of doxorubicin, camptothecin, paclitaxel, and platinum(II) complexes. Another class of polymer therapeutics are drug-delivery systems based on well-defined multivalent and dendritic polymers. These include polyanionic polymers for the inhibition of virus attachment, polycationic complexes with DNA or RNA (polyplexes), and dendritic core-shell architectures for the encapsulation of drugs. In this Review an overview of polymer therapeutics is presented with a focus on concepts and examples that characterize the salient features of the drug-delivery systems.

Low molecular weight fucoidan and its fractions inhibit renal epithelial mesenchymal transition induced by TGF-β1 or FGF-2.

PubMed

Li, Xinpeng; Li, Xiaohong; Zhang, Quanbin; Zhao, Tingting

2017-12-01

We investigated the renal protective effects of low molecular weight fucoidan (LMWF) and its two fractions (F0.5 and F1.0), which were extracted from Laminaria japonica, on the epithelial-mesenchymal transition (EMT) induced by transforming growth factor beta 1 (TGF-β1) and fibroblast growth factor 2 (FGF-2) in HK-2 human renal proximal tubular cells. Cell morphology and EMT markers (fibronectin and alpha-smooth muscle actin) demonstrated that cells treated with TGF-β1 or FGF-2 developed EMT to a significant extent. Treatment with LMWF or its fractions markedly attenuated the EMT and decreased expression of the EMT markers. The F1.0 fraction, the sulfated fucan fraction, was found to be the main active component of LMWF, and heparanase (HPSE) was a key factor in renal tubular epithelial trans-differentiation. The F1.0 fraction inhibited elevated HPSE and matrix metallopeptidase 9 expression, thereby attenuating the progress of EMT. Copyright © 2017 Elsevier B.V. All rights reserved.

The effect of natural organic matter polarity and molecular weight on NDMA formation from two antibiotics containing dimethylamine functional groups.

PubMed

Leavey-Roback, Shannon L; Krasner, Stuart W; Suffet, Irwin H Mel

2016-12-01

N-nitrosodimethylamine (NDMA) is a disinfection byproduct preferentially formed in chloraminated water. NDMA may be formed from certain chemicals containing dimethylamine (DMA) functional groups. This reaction may be slowed by the presence of natural organic matter (NOM). In this study, NOM fractionated by size or polarity was tested for its ability to slow or impede the formation of NDMA from two DMA-containing precursors, the antibiotics tetracycline and spiramycin. The high molecular weight NOM fractions (>10KDa) were shown to be the most effective in reducing the amount of NDMA formed from the precursor chemicals. The filtrate of a C-18 non-polar cartridge was also effective at reducing NDMA formation from tetracycline (spyramycin not tested). Therefore, polar and charged NOM components may be responsible for the reduction in NDMA formation. A possible mechanism for the reduction of NDMA formation from tetracycline is complexation due to the hydrogen bonding of the DMA functional group on tetracycline to polar phenolic functional groups in the NOM. Copyright © 2016 Elsevier B.V. All rights reserved.

Anti-HCV effect of Lentinula edodes mycelia solid culture extracts and low-molecular-weight lignin.

PubMed

Matsuhisa, Koji; Yamane, Seiji; Okamoto, Toru; Watari, Akihiro; Kondoh, Masuo; Matsuura, Yoshiharu; Yagi, Kiyohito

2015-06-19

Lentinula edodes mycelia solid culture extract (MSCE) contains several bioactive molecules, including some polyphenolic compounds, which exert immunomodulatory, antitumor, and hepatoprotective effects. In this study, we examined the anti-hepatitis C virus (HCV) activity of MSCE and low-molecular-weight lignin (LM-lignin), which is the active component responsible for the hepatoprotective effect of MSCE. Both MSCE and LM-lignin inhibited the entry of two HCV pseudovirus (HCVpv) types into Huh7.5.1 cells. LM-lignin inhibited HCVpv entry at a lower concentration than MSCE and inhibited the entry of HCV particles in cell culture (HCVcc). MSCE also inhibited HCV subgenome replication. LM-lignin had no effect on HCV replication, suggesting that MSCE contains additional active substances. We demonstrate here for the first time the anti-HCV effects of plant-derived LM-lignin and MSCE. The hepatoprotective effect of LM-lignin suggests that lignin derivatives, which can be produced in abundance from existing plant resources, may be effective in the treatment of HCV-related diseases. Copyright © 2015 Elsevier Inc. All rights reserved.

Chromatographic and Spectral Analysis of Two Main Extractable Compounds Present in Aqueous Extracts of Laminated Aluminum Foil Used for Protecting LDPE-Filled Drug Vials

PubMed Central

Akapo, Samuel O.; Syed, Sajid; Mamangun, Anicia; Skinner, Wayne

2009-01-01

Laminated aluminum foils are increasingly being used to protect drug products packaged in semipermeable containers (e.g., low-density polyethylene (LDPE)) from degradation and/or evaporation. The direct contact of such materials with primary packaging containers may potentially lead to adulteration of the drug product by extractable or leachable compounds present in the closure system. In this paper, we described a simple and reliable HPLC method for analysis of an aqueous extract of laminated aluminum foil overwrap used for packaging LDPE vials filled with aqueous pharmaceutical formulations. By means of combined HPLC-UV, GC/MS, LC/MS/MS, and NMR spectroscopy, the two major compounds detected in the aqueous extracts of the representative commercial overwraps were identified as cyclic oligomers with molecular weights of 452 and 472 and are possibly formed from poly-condensation of the adhesive components, namely, isophthalic acid, adipic acid, and diethylene glycol. Lower molecular weight compounds that might be associated with the “building blocks” of these compounds were not detected in the aqueous extracts. PMID:20140083

Zeolitic imidazolate framework-methacrylate composite monolith characterization by inverse gas chromatography.

PubMed

Yusuf, Kareem; Badjah-Hadj-Ahmed, Ahmed Yacine; Aqel, Ahmad; Aouak, Taieb; ALOthman, Zeid Abdullah

2016-04-22

Thermodynamic characterization of butyl methacrylate-co-ethylene dimethacrylate neat monolith and zeolitic imidazolate framework-8 incorporated with butyl methacrylate-co-ethylene dimethacrylate composite monolith were studied using inverse gas chromatography at infinite dilution under 1MPa column pressure and various column temperatures. The free energy of adsorption (ΔGA), enthalpy of adsorption (ΔHA) and entropy of adsorption (ΔSA) were determined using a series of n-alkanes. The dispersive component of surface energy (γS(D)) was estimated by Dorris-Gray and Schultz et al. The composite monolith showed a more energetic surface than the neat monolith. The acidic, KA, and basic, KD, parameters for both materials were estimated using a group of polar probes. A basic character was concluded with more basic behavior for the neat monolith. Flory-Huggins parameter, χ, was taken as a measure of miscibility between the probes with the low molecular weight and the high molecular weight monolith. Inverse gas chromatography provides a better understanding of the role of incorporated zeolitic imidazolate framework (ZIF-8) into the polymer matrix in its monolithic form. Copyright © 2016 Elsevier B.V. All rights reserved.

Strategies for Characterization of Low-Abundant Intact or Truncated Low-Molecular-Weight Proteins From Human Plasma.

PubMed

Cai, Tanxi; Yang, Fuquan

2017-01-01

Low-molecular-weight region (LMW, MW≤30kDa) of human serum/plasma proteins, including small intact proteins, truncated fragments of larger proteins, along with some other small components, has been associated with the ongoing physiological and pathological events, and thereby represent a treasure trove of diagnostic molecules. Great progress in the mining of novel biomarkers from this diagnostic treasure trove for disease diagnosis and health monitoring has been achieved based on serum samples from healthy individuals and patients and powerful new approaches in biochemistry and systems biology. However, cumulative evidence indicates that many potential LMW protein biomarkers might still have escaped from detection due to their low abundance, the dynamic complexity of serum/plasma, and the limited efficiency of characterization approaches. Here, we provide an overview of the current state of knowledge with respect to strategies for the characterization of low-abundant LMW proteins (small intact or truncated proteins) from human serum/plasma, involving prefractionation or enrichment methods to reduce dynamic range and mass spectrometry-based characterization of low-abundant LMW proteins. © 2017 Elsevier Inc. All rights reserved.

The solubilization of bone and dentin collagens by pepsin. Effect of cross-linkages and non-collagen components.

PubMed

Carmichael, D J; Dodd, C M; Veis, A

1977-03-28

Bone and dentin collagen are less susceptible to solubilization by pepsin digestion then is skin collagen. Digestion at 4 degrees C for 72 h solubilized only 35.3% of bovine cortical bone and 5.6% of bovine dentin compared with nearly 100% dissolution of bovine skin. Sodium dodecyl sulfate-acrylamide gel electrophoresis and molecular sieve chromatography showed that, for bone and dentin, intact alpha chains and cross-linked aggregates of beta, gamma and higher weight remained intact after pepsin solubilization but lower molecular weight fragments also were prevalent indicating chain scission in helical regions. Electron microscopic examination of segment long spacing precipitates of the soluble collagens confirmed the presence of solubilized polymerized collagen. The principal reducible cross-link in both bone and dentin was the precursor of dihydroxylsinonorleucine and this cross-link was also present in the solubilized collagens. Small amounts of non-collagenous proteins and glycosaminoglycans of different compositions in dentin and bone resisted extraction before pepsin digestion. However, the differences in solubilization of the collagens have been related to differences in cross-linkage placement.

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

PubMed

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.

Serum immunoglobulin E and immunoglobulin G reactivity to Agaricus bisporus proteins in mushroom cultivation workers.

PubMed

Khakzad, Z; Hedayati, M T; Mahdian, S; Mayahi, S

2015-06-01

Although molds are regarded as the main fungal allergen sources, evidence indicates that spores of Basidiomycota including Agaricus bisporus ( A. bisporus ) can be also found at high concentrations in the environment and may cause as many respiratory allergies as molds. The aim of the present study was to evaluate specific immunoglobulin E (IgE) and immunoglobulin G (IgG) antibodies against A. bisporus via immunoblotting technique in individuals working at mushroom cultivation centers. In this study, 72 workers involved in the cultivation and harvest of button mushrooms were enrolled. For the analysis of serum IgE and IgG, A. bisporus grown in Sabouraud dextrose broth was harvested and ruptured by liquid nitrogen and glass beads. The obtained sample was centrifuged and the supernatant was collected as "crude extract" (CE). CE was separated via Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). The separated proteins were transferred to a nitrocellulose filter and the bands responsive to IgE and IgG were identified by anti-human conjugated antibodies. All participants were screened in terms of total IgE level. Among 72 workers, 18 (25%) had a total IgE level higher than 188 IU/mL. In SDS-PAGE, the CE of A. bisporus showed 23 different protein bands with a molecular weight range of 13-80 kDa. The sera of 23.6% and 55.5% of participants showed positive response, with specific IgE and IgG antibodies against A. bisporus in the blot, respectively. The bands with molecular weights of 62 and 68 kDa were the most reactive protein components of A. bisporus to specific IgE antibodies. Moreover, bands with molecular weights of 57 and 62 kDa showed the highest reactivity to IgG, respectively. Also, 62 and 68 kDa components were the most reactive bands with both specific IgG and IgE antibodies. The obtained findings revealed that A. bisporus has different allergens and antigens, which contribute to its potential as an aeroallergen in hypersensitivity-related reactions of the lungs.

[The value of low-molecular-weight DNA of blood plasma in the diagnostic of the patological processes of different genesis].

PubMed

Vasil'eva, I N; Zinkin, V N

2013-01-01

The low-molecular-weight DNA appears in blood plasma of irradiated rats, and its content correlates directly with the irradiation dose. Cloning has shown, that enrichment of low-molecular-weight DNA with G+C content and features of its nucleotide sequences point to its ability to form rather stable nucleosomes. DNA obtained after irradiation of rats with principally different doses 8 and 100 Gy differed not only quantitatively, but also by content of the dinucleotides CpG and CpT; this suggests their origin from different sites of genome. For the first time it has been shown that exposure to low-frequency noise results in an increase of the contents of blood plasma low-molecular-weight DNA. In stroke patients blood concentrations of this DNA increased 3 days after the beginning of the acute period, and dynamics of its excretion differs in ischemic and hemorrhagic forms; in the case of ischemia low-molecular-weight DNA appears in cerebrospinal fluid. The chronic obstructive pulmonary disease in the state of remission is characterized by the decline of the level of low-molecular-weight DNA in the blood plasma unlike in the case of the chronic nonobstructive bronchitis. The clear dependence between formation and special features of the low-molecular-weight DNA fraction in blood plasma makes it possible to consider the low-molecular fraction as an universal index of apoptosis, which allows to distinguish basically different conditions of the body.

Fossil fuel combined cycle power system

DOEpatents

Labinov, Solomon Davidovich; Armstrong, Timothy Robert; Judkins, Roddie Reagan

2006-10-10

A system for converting fuel energy to electricity includes a reformer for converting a higher molecular weight gas into at least one lower molecular weight gas, at least one turbine to produce electricity from expansion of at least one of the lower molecular weight gases, and at least one fuel cell. The system can further include at least one separation device for substantially dividing the lower molecular weight gases into at least two gas streams prior to the electrochemical oxidization step. A nuclear reactor can be used to supply at least a portion of the heat the required for the chemical conversion process.

Effect of sterilization irradiation on friction and wear of ultrahigh-molecular-weight polyethylene

NASA Technical Reports Server (NTRS)

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

1979-01-01

The effect of sterilization gamma irradiation on the friction and wear properties of ultrahigh molecular weight polyethylene (UHMWPE) sliding against 316L stainless steel in dry air at 23 C was determined. A pin-on-disk apparatus was used. Experimental conditions included a 1-kilogram load, a 0.061- to 0.27-meter-per-second sliding velocity, and a 32000- to 578000-meter sliding distance. Although sterilization doses of 2.5 and 5.0 megarads greatly altered the average molecular weight and the molecular weight distribution, the friction and wear properties of the polymer were not significantly changed.

Low molecular weight species in humic and fulvic fractions

USGS Publications Warehouse

Wilson, M.A.; Collin, P.J.; Malcolm, R.L.; Perdue, E. Michael; Cresswell, P.

1988-01-01

Fourier transform solution 1H nuclear magnetic resonance (NMR) spectrometry with homogated water peak irradiation is a useful method for detecting low molecular weight substances in humic extracts. Succinate, acetate, methanol, formate, lactate and some aryl methoxyl compounds have been detected in extracts from a wide range of sources. In view of the controversy over whether low molecular weight substances are contaminants in humic extracts introduced by the concentration procedure, we report that some of these materials are not contaminants since 1H-NMR can be used to follow their formation from higher molecular weight species. ?? 1988.

Morphology and protein molecular weight analysis from three variant of oil palm pollen; Dura, Pisifera, and Tenera

NASA Astrophysics Data System (ADS)

Priambodo, R.; Witarto, A. B.; Salamah, A.; Setiorini, Triyono, D.; Bowolaksono, A.

2017-07-01

Oil palm is a plant that widely cultivated in Indonesia, with an area of about 11 million hectares in 2014. There are three main variants that most cultivated; Dura, Pisifera, and Tenera. Oil palm pollen was spread through the wind. The very wide area of oil palm plantation and those characteristics of oil palm pollen dispersion makes oil palm pollen may give negative effect to the people around plantation, such as an allergy. The research on the morphology and protein characters of the oil palm pollen from three variants has not done yet. This research aims to observe the morphology and protein character from three variants of oil palm pollen. The study begins with the pollen collection from three variants of oil palm. Oil palm pollen was observed using the light and scanning electron microscope. Oil palm pollen protein was extracted and the molecular weight of these proteins was analyzed. The result of this research was the morphology character from three variants of oil palm pollen have successfully been observed. Those three variant of oil palm have no differences structures; triangular shaped with round edge, tricolpate with connected colpus aperture, psilate exine ornamentation at the front side and peripheral side, while at the back side has microreticulate exine ornamentation. Three variants of oil palm pollen protein show the same characteristics. The molecular weight of the protein was ranged from 10-00 KDa. The information can be useful for the next research to figure out component of proteins inside the oil palm pollen.

Packaging of Polyelectrolytes in Viral Capsids: The Interplay Between Polymer Length and Capsid Size

NASA Astrophysics Data System (ADS)

Knobler, Charles

2008-03-01

Each particle of the Cowpea Chlorotic Mottle Virus (CCMV) has a very small ``parts list,'' consisting of two components: a molecule of single-stranded RNA and a 190-residue protein that makes up the 28-nm diameter icosahedral capsid. When purified viral RNA and capsid protein are mixed in solution at an appropriate pH and ionic strength, infectious wild-type viruses form spontaneously. Virus-like particles (VLPs) are formed when the protein self assembles around other anionic polymers such as poly(styrene sulfonate) (PSS). Under different pH and ionic strength conditions the capsid protein can assemble by itself into empty capsids, multishell structures, tubes and sheets. To explore the effect on virion size of the competition between the preferred curvature of the protein and the size of the packaged cargo we have examined the formation of VLPs around PSS polymers with molecular weights ranging from 400 kDa to 3.4 MDa. Two distinct sizes are observed -- 22 nm for the lower molecular weights, jumping to 27 nm at 2 MDa. While under given conditions the size of PSS in solution is directly determined by its molecular weight, the self-complementarity of RNA makes its solution structure dependent on the nucleotide sequence as well. We have therefore employed Small-Angle X-ray Scattering and Fluorescence Correlation Spectroscopy to examine the sizes of viral and non-viral RNAs of identical lengths. A model for the assembly that includes both the self-interactions of the polyelectrolyte and the capsid proteins and the interactions between them provides insight into the experimental results.

Fundamental Studies on Donor-acceptor Conjugated Polymers Containing 'Heavy' Group 14 and Group 16 Elements

NASA Astrophysics Data System (ADS)

Gibson, Gregory Laird

One advantage of conjugated polymers as organic materials is that their properties may be readily tuned through covalent modifications. This thesis presents studies on the structure-property relationships resulting from single- and double-atom substitutions on an alternating donor-acceptor conjugated polymer. Specifically, single selenium and tellurium atoms have been incorporated into the acceptor monomer in place of sulfur; silicon and germanium atoms have been substituted in place of carbon at the donor monomer bridge position. The carbon-donor/ tellurium-acceptor polymer was synthesized by a post-polymerization reaction sequence and demonstrated the utility of heavy group 16 atoms to red shift a polymer absorption spectrum. Density functional theory calculations point to a new explanation for this result invoking the lower heavy atom ionization energy and reduced aromaticity of acceptor monomers containing selenium and tellurium compared to sulfur. Absorption and emission experiments demonstrate that both silicon and germanium substitutions in the donor slightly blue shift the polymer absorption spectrum. Polymers containing sulfur in the acceptor are the strongest light absorbers of all polymers studied here. Molecular weight and phenyl end capping studies show that molecular weight appears to affect polymer absorption to the greatest degree in a medium molecular weight regime and that these effects have a significant aggregation component. Solar cell devices containing either the silicon- or germanium-donor/selenium-acceptor polymer display improved red light harvesting or hole mobility relative to their structural analogues. Overall, these results clarify the effects of single atom substitution on donor-acceptor polymers and aid in the future design of polymers containing heavy atoms.

Factors that affect molecular weight distribution of Suwannee river fulvic acid as determined by electrospray ionization/mass spectrometry

USGS Publications Warehouse

Rostad, C.E.; Leenheer, J.A.

2004-01-01

Effects of methylation, molar response, multiple charging, solvents, and positive and negative ionization on molecular weight distributions of aquatic fulvic acid were investigated by electrospray ionization/mass spectrometry. After preliminary analysis by positive and negative modes, samples and mixtures of standards were derivatized by methylation to minimize ionization sites and reanalyzed.Positive ionization was less effective and produced more complex spectra than negative ionization. Ionization in methanol/water produced greater response than in acetonitrile/water. Molar response varied widely for the selected free acid standards when analyzed individually and in a mixture, but after methylation this range decreased. After methylation, the number average molecular weight of the Suwannee River fulvic acid remained the same while the weight average molecular weight decreased. These differences are probably indicative of disaggregation of large aggregated ions during methylation. Since the weight average molecular weight decreased, it is likely that aggregate formation in the fulvic acid was present prior to derivatization, rather than multiple charging in the mass spectra. ?? 2004 Elsevier B.V. All rights reserved.

Correlation of transarterial transport of various dextrans with their physicochemical properties.

PubMed

Elmalak, O; Lovich, M A; Edelman, E

2000-11-01

Local vascular drug delivery provides elevated concentrations of drug in the target tissue while minimizing systemic side effects. To better characterize local pharmacokinetics we examined the arterial transport of locally applied dextran and dextran derivatives in vivo. Using a two-compartment pharmacokinetic model to correct the measured transmural flux of these compounds for systemic redistribution and elimination as delivered from a photopolymerizable hydrogel surrounding rat carotid arteries, we found that the diffusivities and the transendothelial permeabilities were strongly dependent on molecular weight and charge. For neutral dextrans, the effective diffusive resistance in the media increased with molecular weight approximately 4.1-fold between the molecular weights of 10 and 282 kDa. Similarly, endothelial resistance increased 28-fold over the same molecular weight range. The effective medial diffusive resistance was unaffected by cationic charge as such molecules moved identically to neutral compounds, but increased approximately 40% when dextrans were negatively charged. Transendothelial resistance was 20-fold lower for the cationic dextrans, and 11-fold higher for the anionic dextrans, when both were compared to neutral counterparts. These results suggest that, while low molecular weight drugs will rapidly traverse the arterial wall with the endothelium posing a minimal barrier, the reverse is true for high molecular weight agents. With these data, the deposition and distribution of locally released vasotherapeutic compounds might be predicted based upon chemical properties, such as molecular weight and charge.

Heat-mediated, ultra-rapid electrophoretic transfer of high and low molecular weight proteins to nitrocellulose membranes.

PubMed

Kurien, Biji T; Scofield, R Hal

2002-08-01

Here, we report an ultra-rapid method for the transfer of high and low molecular weight proteins to nitrocellulose membranes following sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In this procedure, the electro-transfer was performed with heated (70-75 degrees C) normal transfer buffer from which methanol had been omitted. Complete transfer of high and low molecular weight proteins (a purified protein, molecular weight protein standards and proteins from a human tissue extract) could be carried out in 10 min for a 0.75-mm, 7% SDS-PAGE gel. For 10% and 12.5% gels (0.75 mm), the corresponding time was 15 min. In the case of 1.5-mm gels, a complete transfer could be carried out in 20 min for 7%, 10% and 12.5% gels. The permeability of the gel is increased by heat, such that the proteins trapped in the polyacrylamide gel matrix can be easily transferred to the membrane. When the heat-mediated transfer method was compared with a conventional transfer protocol, under similar conditions, we found that the latter method transferred minimal low molecular weight proteins while retaining most of the high molecular weight proteins in the gel. In summary, this procedure is very rapid, avoids the use of methanol and is particularly useful for the transfer of high molecular weight proteins.

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

DOE PAGES

Dixon, Alex G.; Visvanathan, Rayshan; Clark, Noel A.; ...

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 = 48more » 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.« less

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

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

Dixon, Alex G.; Visvanathan, Rayshan; Clark, Noel A.

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 = 48more » 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.« less

Characterization of isolated fractions of dissolved organic matter derived from municipal solid waste compost.

PubMed

Yu, Minda; He, Xiaosong; Liu, Jiaomei; Wang, Yuefeng; Xi, Beidou; Li, Dan; Zhang, Hui; Yang, Chao

2018-04-14

Understanding the heterogeneous evolution characteristics of dissolved organic matter fractions derived from compost is crucial to exploring the composting biodegradation process and the possible applications of compost products. Herein, two-dimensional correlation spectroscopy integrated with reversed-phase high performance liquid chromatography and size exclusion chromatography were utilized to obtain the molecular weight (MW) and polarity evolution characteristics of humic acid (HA), fulvic acid (FA), and the hydrophilic (HyI) fractions during composting. The high-MW humic substances and building blocks in the HA fraction degraded faster during composting than polymers, proteins, and organic colloids. Similarly, the low MW acid FA factions transformed faster than the low weight neutral fractions, followed by building blocks, and finally polymers, proteins, and organic colloids. The evolutions of HyI fractions during composting occurred first for building blocks, followed by low MW acids, and finally low weight neutrals. With the progress of composting, the hydrophobic properties of the HA and FA fractions were enhanced. The degradation/humification process of the hydrophilic and transphilic components was faster than that of the hydrophobic component. Compared with the FA and HyI fractions, the HA fraction exhibited a higher MW and increased hydrophobicity. Copyright © 2018 Elsevier B.V. All rights reserved.

Characterization of reaction intermediate aggregates in aniline oxidative polymerization at low proton concentration.

PubMed

Ding, Zhongfen; Sanchez, Timothy; Labouriau, Andrea; Iyer, Srinivas; Larson, Toti; Currier, Robert; Zhao, Yusheng; Yang, Dali

2010-08-19

Aggregates of reaction intermediates form during the early stages of aniline oxidative polymerization whenever the initial mole ratio of proton concentration to aniline monomer concentration is low ([H(+)](0)/[An](0)

Effect of different molecular weight organic components on the increase of microbial growth potential of secondary effluent by ozonation.

PubMed

Zhao, Xin; Hu, Hong-Ying; Yu, Tong; Su, Chang; Jiang, Haochi; Liu, Shuming

2014-11-01

Ozonation has been widely applied in advanced wastewater treatment. In this study, the effect of ozonation on assimilable organic carbon (AOC) levels in secondary effluents was investigated, and AOC variation of different molecular weight (MW) organic components was analyzed. Although the removal efficiencies were 47%-76% and 94%-100% for UV254 and color at ozone dosage of 10mg/L, dissolved organic carbon (DOC) in secondary effluents was hardly removed by ozonation. The AOC levels increased by 70%-780% at an ozone dosage range of 1-10mg/L. AOC increased significantly in the instantaneous ozone demand phase, and the increase in AOC was correlated to the decrease in UV254 during ozonation. The results of MW distribution showed that, ozonation led to the transformation of larger molecules into smaller ones, but the increase in low MW (<1kDa) fraction did not contribute much to AOC production. The change of high MW (>100kDa and 10-100kDa) fractions itself during ozonation was the main reason for the increase of AOC levels. Furthermore, the oxidation of organic matters with high MWs (>100kDa and 10-100kDa) resulted in more AOC production than those with low MWs (1-10kDa and <1kDa). The results indicated that removing large molecules in secondary effluents could limit the increase of AOC during ozonation. Copyright © 2014. Published by Elsevier B.V.

Design, Optimization, and Evaluation of a Novel Metronidazole-Loaded Gastro-Retentive pH-Sensitive Hydrogel.

PubMed

El-Mahrouk, Galal M; Aboul-Einien, Mona H; Makhlouf, Amal I

2016-12-01

Floating pH-sensitive chitosan hydrogels containing metronidazole were developed for the eradication of Helicobacter pylori from the stomach. Hydrogels were prepared by crosslinking medium or high molecular weight chitosan in lyophilized solutions containing metronidazole using either citrate or tripolyphosphate (TPP) salts at 1% or 2% concentration. A 2 3 factorial design was developed to study the influence of formulation parameters on the physical characteristics of the prepared hydrogels. The interaction between hydrogel components was investigated. The morphology of the prepared hydrogels was inspected and their percentage swelling, release pattern, and moisture content were evaluated. The results revealed the absence of interaction between hydrogel components and their highly porous structure. Percentage swelling of the hydrogels was much higher, and drug release was faster in gastric pH compared with intestinal pH. The formula prepared using 2% high molecular weight chitosan and 2% TPP significantly swelled (700%) within the first 4 h and released the loaded drug over a period of 24 h. Its moisture content was not affected by storage at high relative humidity. Therefore, this formula was selected to be tested in dogs for its gastric retention (using X-ray radiography) and efficacy in the eradication of H. pylori (using histopathological and microbiological examination). The results revealed that the prepared hydrogel formula was retained in dog stomach for at least 48 h, and it was more effective against H. pylori than the commercially available oral metronidazole tablets (Flagyl®).

Fluorescence spectroscopy and molecular weight distribution of extracellular polymers from full-scale activated sludge biomass.

PubMed

Esparza-Soto, M; Westerhoff, P K

2001-01-01

Two fractions of extracellular polymer substances (EPSs), soluble and readily extractable (RE), were characterised in terms of their molecular weight distributions (MWD) and 3-D excitation-emission-matrix (EEM) fluorescence spectroscopy signatures. The EPS fractions were different: the soluble EPSs were composed mainly of high molecular weight compounds, while the RE EPSs were composed of small molecular weight compounds. Contrary to previous thought, EPS may not be considered only as macromolecular because most organic matter present in both fractions had low molecular weight. Three different fluorophore peaks were identified in the EEM fluorescence spectra. Two peaks were attributed to protein-like fluorophores, and the third to a humic-like fluorophore. Fluorescence signatures were different from other previously published signatures for marine and riverine environments. EEM spectroscopy proved to be a suitable method that may be used to characterise and trace organic matter of bacterial origin in wastewater treatment operations.

Effect of the different chain transfer agents on molecular weight and optical properties of poly(methyl methacrylate)

NASA Astrophysics Data System (ADS)

Çetinkaya, Onur; Demirci, Gökhan; Mergo, Paweł

2017-08-01

Investigation of molecular weight and optical properties of poly(methyl metacrylate) (PMMA) polymerized in house with different chain transfer agents was studied. Isopropyl alcohol (IPA), n-butyl mercaptan (nBMC) and pentamethyl disilane (PMDS) were used as chain transfer agents. The molecular weight (Mw) of PMMA samples were measured by Ostwald viscometer. Mw of bulk polymer samples were decreased with increase the concentration of chain transfer agents (CTA). Since reactivity of used CTAs is not same, molecular weights of samples which were produced with different type of CTA but same concentration of CTA was varied. Higher concentration of n-BMC showed higher scattering. Transmission of samples could not be correlated with different concentration of CTA. Refractive index of samples was not affected by concentration of CTA nevertheless higher molecular weight of CTA showed higher refractive index.

Low molecular weight salts combined with fluorinated solvents for electrolytes

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

Tikhonov, Konstantin; Yip, Ka Ki; Lin, Tzu-Yuan

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, twicemore » 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.« less

Manipulation of Molecular Weight Distribution Shape as a New Strategy to Control Processing Parameters.

PubMed

Nadgorny, Milena; Gentekos, Dillon T; Xiao, Zeyun; Singleton, S Parker; Fors, Brett P; Connal, Luke A

2017-10-01

Molecular weight and dispersity (Ð) influence physical and rheological properties of polymers, which are of significant importance in polymer processing technologies. However, these parameters provide only partial information about the precise composition of polymers, which is reflected by the shape and symmetry of molecular weight distribution (MWD). In this work, the effect of MWD symmetry on thermal and rheological properties of polymers with identical molecular weights and Ð is demonstrated. Remarkably, when the MWD is skewed to higher molecular weight, a higher glass transition temperature (T g ), increased stiffness, increased thermal stability, and higher apparent viscosities are observed. These observed differences are attributed to the chain length composition of the polymers, easily controlled by the synthetic strategy. This work demonstrates a versatile approach to engineer the properties of polymers using controlled synthesis to skew the shape of MWD. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Apparatus for molecular weight separation

DOEpatents

Smith, Richard D.; Liu, Chuanliang

2001-01-01

The present invention relates generally to an apparatus and method for separating high molecular weight molecules from low molecular weight molecules. More specifically, the invention relates to the use of microdialysis for removal of the salt (low molecular weight molecules) from a nucleotide sample (high molecular weight molecules) for ESI-MS analysis. The dialysis or separation performance of the present invention is improved by (1) increasing dialysis temperature thereby increasing desalting efficiency and improving spectrum quality; (2) adding piperidine and imidazole to the dialysis buffer solution and reducing charge states and further increasing detection sensitivity for DNA; (3) using low concentrations (0-2.5 mM NH4OAc) of dialysis buffer and shifting the DNA negative ions to higher charge states, producing a nearly 10-fold increase in detection sensitivity and a slightly decreased desalting efficiency, (4) conducting a two-stage separation or (5) any combination of (1), (2), (3) and (4).

Microdialysis unit for molecular weight separation

DOEpatents

Smith, Richard D.; Liu, Chuanliang

1999-01-01

The present invention relates generally to an apparatus and method for separating high molecular weight molecules from low molecular weight molecules. More specifically, the invention relates to the use of microdialysis for removal of the salt (low molecular weight molecules) from a nucleotide sample (high molecular weight molecules) for ESI-MS analysis. The dialysis or separation performance of the present invention is improved by (1) increasing dialysis temperature thereby increasing desalting efficiency and improving spectrum quality; (2) adding piperidine and imidazole to the dialysis buffer solution and reducing charge states and further increasing detection sensitivity for DNA; (3) using low concentrations (0-2.5 mM NH4OAc) of dialysis buffer and shifting the DNA negative ions to higher charge states, producing a nearly 10-fold increase in detection sensitivity and a slightly decreased desalting efficiency, or (4) any combination of (1), (2), and (3).

A System And Method To Determine Thermophysical Properties Of A Multi-Component Gas At Arbitrary Temperature And Pressure

DOEpatents

Morrow, Thomas E.; Behring, II, Kendricks A.

2004-03-09

A method to determine thermodynamic properties of a natural gas hydrocarbon, when the speed of sound in the gas is known at an arbitrary temperature and pressure. Thus, the known parameters are the sound speed, temperature, pressure, and concentrations of any dilute components of the gas. The method uses a set of reference gases and their calculated density and speed of sound values to estimate the density of the subject gas. Additional calculations can be made to estimate the molecular weight of the subject gas, which can then be used as the basis for mass flow calculations, to determine the speed of sound at standard pressure and temperature, and to determine various thermophysical characteristics of the gas.

Device For Determining Therophysical Properties Of A Multi-Component Gas At Arbitrary Temperature And Pressure

DOEpatents

Morrow, Thomas B.; Behring, II, Kendricks A.

2005-02-01

A computer product for determining thermodynamic properties of a natural gas hydrocarbon, when the speed of sound in the gas is known at an arbitrary temperature and pressure. Thus, the known parameters are the sound speed, temperature, pressure, and concentrations of any dilute components of the gas. The method uses a set of reference gases and their calculated density and speed of sound values to estimate the density of the subject gas. Additional calculations can be made to estimate the molecular weight of the subject gas, which can then be used as the basis for mass flow calculations, to determine the speed of sound at standard pressure and temperature, and to determine various thermophysical characteristics of the gas.

Selection of components for the IDEALHY preferred cycle for the large scale liquefaction of hydrogen

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

Quack, H.; Seemann, I.; Klaus, M.

2014-01-29

In a future energy scenario, in which storage and transport of liquid hydrogen in large quantities will be used, the efficiency of the liquefaction of hydrogen will be of utmost importance. The goal of the IDEALHY working party is to identify the most promising process for a 50 t/d plant and to select the components, with which such a process can be realized. In the first stage the team has compared several processes, which have been proposed or realized in the past. Based on this information a process has been selected, which is thermodynamically most promising and for which itmore » could be assumed that good components already exist or can be developed in the foreseeable future. Main features of the selected process are the compression of the feed stream to a relatively high pressure level, o-p conversion inside plate-fin heat exchangers and expansion turbines in the supercritical region. Precooling to a temperature between 150 and 100 K will be obtained from a mixed refrigerant cycle similar to the systems used successfully in natural gas liquefaction plants. The final cooling will be produced by two Brayton cycles, both having several expansion turbines in series. The selected overall process has still a number of parameters, which can be varied. The optimum, i.e. the final choice will depend mainly on the quality of the available components. Key components are the expansion turbines of the two Brayton cycles and the main recycle compressor, which may be common to both Brayton cycles. A six-stage turbo-compressor with intercooling between the stages is expected to be the optimum choice here. Each stage may consist of several wheels in series. To make such a high efficient and cost-effective compressor feasible, one has to choose a refrigerant, which has a higher molecular weight than helium. The present preferred choice is a mixture of helium and neon with a molecular weight of about 8 kg/kmol. Such an expensive refrigerant requires that the whole refrigeration loop is extremely tight.« less

Drop-on-demand drop formation of polyethylene oxide solutions

NASA Astrophysics Data System (ADS)

Yan, Xuejia; Carr, Wallace W.; Dong, Hongming

2011-10-01

The dynamics of drop-on-demand (DOD) drop formation for solutions containing polyethylene oxide (PEO) have been studied experimentally. Using a piezoelectrical actuated inkjet printhead with the nozzle orifice diameter of 53 μm, experiments were conducted for a series of PEO aqueous solutions with molecular weights ranging from 14 to 1000 kg/mol, polydispersity from 1.02 to 2.5, and concentrations from 0.005 to 10 wt. %. The addition of a small amount of PEO can have a significant effect on the DOD drop formation process, increasing breakup time, decreasing primary drop speed, and decreasing the number of satellite drops in some cases. The effects depend on both molecular weight and concentration. At lower molecular weights (14 and 35 kg/mol), the effect of PEO over the dilute solution regime is insignificant even at concentrations large enough that the solution does not fall in the dilute regime. As PEO molecular weight increased, the effects became significant. For monodispersed PEO solutions, breakup time and primary drop speed closely correlated with effective relaxation time but not for polydispersed PEO. Effective relaxation time depended greatly on molecular weight distribution. Viscosity-average molecular weight, used in calculating effective relaxation time for polydispersed PEO solutions, did not adequately account for high molecular fractions in the molecular weight distribution of the polydispersed PEOs. A mixture rule was developed to calculate the effective relaxation times for aqueous solutions containing mixtures of monodispersed PEO, and breakup times and primary drop speeds correlated well with effective relaxation times. For our experiments, DOD drop formation was limited to Deborah number ≲ 23.

Overview of the TREC 2009 Chemical IR Track

DTIC Science & Technology

2009-11-01

several classes have been identified. 3 methods for controlling molecular weight of polyhydroxyalkanoate organic, high molecular weight We are a group of...researchers in an university/company. We want to start a project and, before starting, we want more informations about polyhydroxyalkanoate and about...methods for controlling molecular weight of polyhydroxyalkanoate constituted of units containing residue of phenyl-, thienyl-, or cyclohexyl-structure

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

NASA Astrophysics Data System (ADS)

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.

Isolation and Characterization of a Toxic Moiety of Low Molecular Weight from Clostridium botulinum Type A

PubMed Central

Gerwing, Julia; Dolman, Claude E.; Bains, Hardial S.

1965-01-01

Gerwing, Julia (The University of British Columbia, Vancouver, B.C., Canada), Claude E. Dolman, and Hardial S. Bains. Isolation and characterization of a toxic moiety of low molecular weight from Clostridium botulinum type A. J. Bacteriol. 89:1383–1386. 1965.—A toxic moiety of low molecular weight has been isolated from a type A strain of Clostridium botulinum, by a method involving ammonium sulfate precipitation and elution through diethylaminoethyl cellulose at pH 5.6. By means of electrophoresis and ultracentrifugation, the toxic substance was shown to be homogeneous; a molecular weight of 12,200 was calculated. Images PMID:14293025

Mass spectrometric characterization of membrane integral low molecular weight proteins from photosystem II in barley etioplasts.

PubMed

Plöscher, Matthias; Granvogl, Bernhard; Zoryan, Mikael; Reisinger, Veronika; Eichacker, Lutz Andreas

2009-02-01

In Photosystem II (PSII), a high number of plastid encoded and membrane integral low molecular weight proteins smaller than 10 kDa, the proteins PsbE, F, H, I, J, K, L, M, N, Tc, Z and the nuclear encoded PsbW, X, Y1, Y2 proteins have been described. Here we show that all low molecular weight proteins of PSII already accumulate in the etioplast membrane fraction in darkness, whereas PsaI and PsaJ of photosystem I (PSI) represent the only low molecular weight proteins that do not accumulate in darkness. We found by BN-PAGE separation of membrane protein complexes and selective MS that the accumulation of one-helix proteins from PSII is light independent and occurs in etioplasts. In contrast, in chloroplasts isolated from light-grown plants, low molecular weight proteins were found to specifically accumulate in PSI and II complexes. Our results demonstrate how plants grown in darkness prepare for the induction of chlorophyll dependent photosystem assembly upon light perception. We anticipate that our investigation will provide the essential means for the analysis of protein assembly in any membrane utilizing low molecular weight protein subunits.

The Presence Of Strange Males' Odor Induces Behavioral Responses And Elevated Levels Of Low Molecular Weight Proteins Excreted In The Urine Of Mature Water Vole Males (Arvicola amphibius L).

PubMed

Nazarova, Galina G; Proskurniak, Lyudmila P; Yuzhik, Ekaterina I

2016-03-01

We hypothesized that low molecular weight urinary proteins play a role in male-male chemical communication in the water vole, Arvicola ampibius L. We studied the effect of placing soiled litter from strange males into the cage of another sexually mature male on the intensity of its digging and scattering, urination on the litter, and alteration in the levels of low molecular weight proteins (15-25 kDa) excreted in the urine before and after 4 days of exposure as determined by chip electrophoresis. The intensity of digging and scattering was positively correlated with levels of testosterone in serum of males exposed to strange male odors (r = 0.56; P < 0.01), as well as with the concentration of low molecular weight proteins in the donor's urine (r = 0.52, P < 0.05). At the end of the experiment, the level of low molecular weight protein in excreted urine was elevated in the males exposed to the strange male's litter. These results highlight the importance of quantitative inter-individual variation of low molecular weight urinary proteins in the modulation of the physiology and behavior of conspecifics.

Isoleucine epimerization in the high-molecular-weight fraction of pleistocene Arctica

NASA Astrophysics Data System (ADS)

Kaufman, Darrell S.; Sejrup, Hans-Petter

The extent of amino acid racemization, as traditionally determined in the entire (total acid hydrolysate) pool of amino acids comprising the organic remains of fossils, is a function of the integrated effects of a complex diagenetic reaction network. We investigated the possibility that some of the complications involved in protein diagenesis might be circumvented by isolating one component of the reaction network and studying the extent of racemization in that fraction alone. We used gel-filtration to extract the high-molecular-weight (HMW) fraction of proteinaceous matter from fossil and modem molluscan shells. This fraction contains the largest (ca. > 15,000 MW), most-pristine macromolecules and has been less affected by diagenesis than the more-degraded, lower molecular-weight fractions. Variations in the extent of racemization (isoleucine epimerization; alle/Ile) measured in the HMW fraction of subsamples taken along cross sections of Arctica shells from two interglacial sites, Bø and Fjøsanger, southwestern Norway, are within the range of analytical uncertainty [coefficient of variation (cv) = 5-8%], despite the strong gradient (cv = 20-24%) in alle/Ile of the total amino acid population. Because there is no age difference across a shell, this finding supports the idea that the HMW fraction contains more geochronologically reliable proteinaceous matter than the total amino acid pool. Weighted mean alle/Ile ratios in the HMW fraction of aliquots of powdered sample from the two shells overlap at ± 1σ, despite significantly different alle/Ile ratios in the total amino acid population of some shells from the two sites. The difference in alle/Ile ratios in the total population is attributed to a greater proportion of low-molecular-weight (ca. 300 MW), and hence, extensively epimerized molecules measured in gel-filtered samples from the Fjøsanger shell. Because the rate of epimerization in the HMW fraction is much lower than in the total population, the temporal resolution of the HMW technique is limited, particularly at these high-latitude sites. Therefore, we cannot use the aIle/Ile HMW data to exclude the possibility that the two sites are significantly different ages. Analyses of shells ranging in age from late Pliocene to Holocene indicate that reaction rate in the HMW fraction is about one-fifth the rate in the total amino acid population, although the difference is expected to decrease with increasing aIle/Ile.

Effects of Molecular Structure in Macroscopic Mechanical Properties of an Advanced Polymer (LARC(sup TM)-SI)

NASA Technical Reports Server (NTRS)

Nicholson, Lee M.; Hinkley, Jeffrey A.; Whitley, Karen S.; Gates, Thomas S.

2004-01-01

Mechanical testing of an advanced polymer resin with known variations in molecular weight was performed over a range of temperatures below the glass transition temperature. The elastic properties, inelastic elongation behavior, and notched tensile strength all as a function of molecular weight and test temperature were determined. It was shown that notched tensile strength is a strong function of both temperature and molecular weight, whereas stiffness is only a strong function of temperature.

Antibody response of swine to outer membrane components of Haemophilus pleuropneumoniae during infection.

PubMed Central

Rapp, V J; Ross, R F

1986-01-01

Sera from pigs infected with Haemophilus (Actinobacillus) pleuropneumoniae were tested for antibodies to outer membrane proteins (OMPs) of the organism by immunoblotting. Convalescent sera were produced in naturally born, colostrum-fed pigs and in cesarean-derived, colostrum-deprived pigs given H. pleuropneumoniae serotype 5 intranasally twice at 5-week intervals. Sera, collected at weekly intervals, were reacted with Sarkosyl-insoluble, OMP-enriched preparations of H. pleuropneumoniae which had been separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrophoretically transferred to nitrocellulose. Antibodies were detected to OMPs with an apparent molecular weight of 16,500 (16.5K OMP); to 29K, 38.5K, 43.5K, 45K, 49.5K, and 66.5K OMPs; and to several high-molecular-weight (greater than or equal to 94,000) OMPs, but not to the major 42K OMP. Antibodies to the heat-modifiable OMP (29K/43.5K) and the 38.5K OMP were detected in sera from noninfected pigs. Antibodies were also detected to two broad 54,000- and 95,000-molecular-weight bands which did not stain with Coomassie blue, stained with silver nitrate, resisted proteinase K digestion, and were eliminated by oxidation with sodium metaperiodate. This indicates that the 54,000- and 95,000-molecular-weight bands represent polysaccharide, possibly capsular or lipopolysaccharide immunogens. Adsorption of sera with cells from the homologous serotype 5 strain removed antibodies to the 45K, 49.5K, 66.5K, and greater than or equal to 94K OMPs and to the two polysaccharide bands, indicating that these antibodies were directed primarily to surface-exposed epitopes. When tested with OMP preparations from other serotype 5 strains, heterogeneity was apparent, both in the reactions with OMPs and with the polysaccharide bands. Silver staining of proteinase K-treated, whole-cell lysates from serotype 5 strains also indicated variable expression of the polysaccharide bands. Sera also reacted with OMPs from H. pleuropneumoniae serotypes 1 and 7; however, several OMPs and the lipopolysaccharide or polysaccharide determinants of these serotypes appeared to be type specific. Images PMID:3536748

New microbial growth factor

NASA Technical Reports Server (NTRS)

Bok, S. H.; Casida, L. E., Jr.

1977-01-01

A screening procedure was used to isolate from soil a Penicillium sp., two bacterial isolates, and a Streptomyces sp. that produced a previously unknown microbial growth factor. This factor was an absolute growth requirement for three soil bacteria. The Penicillium sp. and one of the bacteria requiring the factor, an Arthrobacter sp., were selected for more extensive study concerning the production and characteristics of the growth factor. It did not seem to be related to the siderochromes. It was not present in soil extract, rumen fluid, or any other medium component tested. It appears to be a glycoprotein of high molecular weight and has high specific activity. When added to the diets for a meadow-vole mammalian test system, it caused an increased consumption of diet without a concurrent increase in rate of weight gain.

Analysis of Organohalogen Products From Chlorination of Natural Waters Under Simulated Biofouling Control Conditions

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

Bean, R. M.; Mann, D. C.; Riley, R. G.

1980-06-01

The products of low-level chlorination of natural waters from ten locations across the continental United States have been studied, with emphasis on volatile and lipophilic organohalogen components. A specially designed apparatus permitted continuous sampling and chlorination of water in a manner analogous to some types of cooling water treatments. Volatile components were analyzed using headspace, purge-and-trap, and resin adsorption methods. The less-volatile components were collected by passing large volumes of the chlorinated water over XAD-2 columns. Total organic halogen collected on XAD resins was compared with the halogen contribution of haloform compounds. The XAD samples were further separated into fractionsmore » according to molecular weight and polarity using liquid chrOmatography. These studies indicate that haloforms are the most abundant lipophilic halogenated products formed from low-level chlorination of natural waters, but that other halogenated lipophilic material is also formed.« less

Effects of molecular weight of natural organic matter on cadmium mobility in soil environments and its carbon isotope characteristics.

PubMed

Mahara, Y; Kubota, T; Wakayama, R; Nakano-Ohta, T; Nakamura, T

2007-11-15

We investigated the role of natural organic matter in cadmium mobility in soil environments. We collected the dissolved organic matter from two different types of natural waters: pond surface water, which is oxic, and deep anoxic groundwater. The collected organic matter was fractionated into four groups with molecular weights (unit: Da (Daltons)) of <1 x 10(3), 1-10 x 10(3), 10-100 x 10(3), and >100 x 10(3). The organic matter source was land plants, based on the carbon isotope ratios (delta(13)C/(12)C). The organic matter in surface water originated from presently growing land plants, based on (14)C dating, but the organic matter in deep groundwater originated from land plants that grew approximately 4000 years ago. However, some carbon was supplied by the high-molecular-weight fraction of humic substances in soil or sediments. Cadmium interacted in a system of siliceous sand, fractionated organic matter, and water. The lowest molecular weight fraction of organic matter (<1 x 10(3)) bound more cadmium than did the higher molecular weight fractions. Organic matter in deep groundwater was more strongly bound to cadmium than was organic matter in surface water. The binding behaviours of organic matter with cadmium depended on concentration, age, molecular weight, and degradation conditions of the organic matter in natural waters. Consequently, the dissolved, low-molecular-weight fraction in organic matter strongly influences cadmium migration and mobility in the environment.

Effect of polyethylene glycols on the trans-ungual delivery of terbinafine.

PubMed

Nair, Anroop B; Chakraborty, Bireswar; Murthy, S Narasimha

2010-12-01

Topical nail drug delivery could be improved by identifying potent chemical penetration enhancers. The purpose of this study was to assess the effect of polyethylene glycols (PEGs) on the trans-ungual delivery of terbinafine. In vitro permeation studies were carried out by passive and iontophoresis (0.5 mA/cm2) processes for a period of 1 h using gel formulations containing different molecular weight PEGs (30%w/w). The release of drug from the loaded nail plates and the possible mechanisms for the enhanced delivery was studied. Passive delivery using formulation with low molecular weight PEGs (200 and 400 MW) indicated moderate enhancement in the permeation and drug load in the nail plate, compared to the control formulation. However, the effect of low molecular weight PEGs was predominant during iontophoresis process with greater amount of terbinafine being permeated (≈35 µg/cm2) and loaded into the nail plate (≈2.7 µg/mg). However, little or no effect on drug delivery was observed with high molecular weight PEGs (1000- 3350 MW) in passive and iontophoresis processes. Release of drug from the nail plates loaded by iontophoresis using low molecular weight PEG (400 MW) exhibited sustain effect which continued over a period of 72 days. The enhancement in drug permeation by low molecular weight PEGs is likely due to their ability to lead to greater water uptake and swelling of nail. This study concluded that the low molecular weight PEGs are indeed a promising trans-ungual permeation enhancer.

CR TKA UHMWPE wear tested after artificial aging of the vitamin E treated gliding component by simulating daily patient activities.

PubMed

Schwiesau, Jens; Fritz, Bernhard; Kutzner, Ines; Bergmann, Georg; Grupp, Thomas M

2014-01-01

The wear behaviour of total knee arthroplasty (TKA) is dominated by two wear mechanisms: the abrasive wear and the delamination of the gliding components, where the second is strongly linked to aging processes and stress concentration in the material. The addition of vitamin E to the bulk material is a potential way to reduce the aging processes. This study evaluates the wear behaviour and delamination susceptibility of the gliding components of a vitamin E blended, ultra-high molecular weight polyethylene (UHMWPE) cruciate retaining (CR) total knee arthroplasty. Daily activities such as level walking, ascending and descending stairs, bending of the knee, and sitting and rising from a chair were simulated with a data set received from an instrumented knee prosthesis. After 5 million test cycles no structural failure of the gliding components was observed. The wear rate was with 5.62 ± 0.53 mg/million cycles falling within the limit of previous reports for established wear test methods.

CR TKA UHMWPE Wear Tested after Artificial Aging of the Vitamin E Treated Gliding Component by Simulating Daily Patient Activities

PubMed Central

Schwiesau, Jens; Fritz, Bernhard; Kutzner, Ines; Bergmann, Georg; Grupp, Thomas M.

2014-01-01

The wear behaviour of total knee arthroplasty (TKA) is dominated by two wear mechanisms: the abrasive wear and the delamination of the gliding components, where the second is strongly linked to aging processes and stress concentration in the material. The addition of vitamin E to the bulk material is a potential way to reduce the aging processes. This study evaluates the wear behaviour and delamination susceptibility of the gliding components of a vitamin E blended, ultra-high molecular weight polyethylene (UHMWPE) cruciate retaining (CR) total knee arthroplasty. Daily activities such as level walking, ascending and descending stairs, bending of the knee, and sitting and rising from a chair were simulated with a data set received from an instrumented knee prosthesis. After 5 million test cycles no structural failure of the gliding components was observed. The wear rate was with 5.62 ± 0.53 mg/million cycles falling within the limit of previous reports for established wear test methods. PMID:25506594

Molecular weight, polydispersity, and spectroscopic properties of aquatic humic substances

USGS Publications Warehouse

Chin, Y.-P.; Aiken, G.; O'Loughlin, E.

1994-01-01

The number- and weight-averaged molecular weights of a number of aquatic fulvic acids, a commercial humic acid, and unfractionated organic matter from four natural water samples were measured by high-pressure size exclusion chromatography (HPSEC). Molecular weights determined in this manner compared favorably with those values reported in the literature. Both recent literature values and our data indicate that these substances are smaller and less polydisperse than previously believed. Moreover, the molecular weights of the organic matter from three of the four natural water samples compared favorably to the fulvic acid samples extracted from similar environments. Bulk spectroscopic properties of the fulvic substances such as molar absorptivity at 280 nm and the E4/E6 ratio were also measured. A strong correlation was observed between molar absorptivity, total aromaticity, and the weight average molecular weights of all the humic substances. This observation suggests that bulk spectroscopic properties can be used to quickly estimate the size of humic substances and their aromatic contents. Both parameters are important with respect to understanding humic substance mobility and their propensity to react with both organic and inorganic pollutants. ?? 1994 American Chemical Society.

Low molecular weight squash trypsin inhibitors from Sechium edule seeds.

PubMed

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.

Silver Coating for High-Mass-Accuracy Imaging Mass Spectrometry of Fingerprints on Nanostructured Silicon.

PubMed

Guinan, Taryn M; Gustafsson, Ove J R; McPhee, Gordon; Kobus, Hilton; Voelcker, Nicolas H

2015-11-17

Nanostructure imaging mass spectrometry (NIMS) using porous silicon (pSi) is a key technique for molecular imaging of exogenous and endogenous low molecular weight compounds from fingerprints. However, high-mass-accuracy NIMS can be difficult to achieve as time-of-flight (ToF) mass analyzers, which dominate the field, cannot sufficiently compensate for shifts in measured m/z values. Here, we show internal recalibration using a thin layer of silver (Ag) sputter-coated onto functionalized pSi substrates. NIMS peaks for several previously reported fingerprint components were selected and mass accuracy was compared to theoretical values. Mass accuracy was improved by more than an order of magnitude in several cases. This straightforward method should form part of the standard guidelines for NIMS studies for spatial characterization of small molecules.

Photoaffinity-labeling and fluorescence-distribution studies of gonadotropin-releasing hormone receptors in ovarian granulosa cells.

PubMed Central

Hazum, E; Nimrod, A

1982-01-01

Photoaffinity labeling of rat ovarian granulosa cells and membrane preparations with a bioactive photoaffinity derivative of gonadotropin-releasing hormone resulted in identification of two specific components with apparent molecular weights of 60,000 and 54,000. Fluorescent visualization of gonadotropin-releasing hormone receptors in these cells, by using a bioactive rhodamine derivative of the hormone, indicated that the fluorescently labeled receptors were initially distributed uniformly on the cell surface and then formed patches that subsequently internalized (at 37 degrees C) into endocytic vesicles. These processes were dependent on specific binding sites for the rhodamine-labeled peptide on the granulosa cells. These studies may provide an experimental basis for understanding the molecular events involved in the action of the hormone in the ovary. Images PMID:6281784

Determination of the thermal stability of perfluoropolyalkyl ethers by tensimetry

NASA Technical Reports Server (NTRS)

Helmick, Larry A.; Jones, William R., Jr.

1992-01-01

The thermal decomposition temperatures of several perfluoropolyalkyl ether fluids were determined with a computerized tensimeter. In general, the decomposition temperatures of the commercial fluids were all similar and significantly higher than those for noncommercial fluids. Correlation of the decomposition temperatures with the molecular structures of the primary components of the commercial fluids revealed that the stability of the fluids was not affected by carbon chain length, branching, or adjacent difluoroformal groups. Instead, stability was limited by the presence of small quantities of thermally unstable material and/or chlorine-containing material arising from the use of chlorine containing solvents during synthesis. Finally, correlation of decomposition temperatures with molecular weights for two fluids supports a chain cleavage reaction mechanism for one and an unzipping reaction mechanism for the other.

40 CFR Table A-7 to Subpart A of... - Data Elements That Are Inputs to Emission Equations and for Which the Reporting Deadline Is March...

Code of Federal Regulations, 2012 CFR

2012-07-01

... mass balance equation. K 98.116(b) Only annual production by product from each EAF (No CEMS). K 98.116... carbon content values, molecular weights for gaseous feedstocks, molecular weights for gaseous products... of gas flared, average molecular weight, carbon content of the flare, and molar volume conversion...

Formation of high molecular weight products from benzene during boundary lubrication

NASA Technical Reports Server (NTRS)

Morales, W.

1985-01-01

High molecular weight products were detected on the wear track of an iron disk at the end of a sliding friction and wear test using benzene as a lubricant. Size exclusion chromagography in conjunction with UV analysis gave evidence that the high molecular weight products are polyphenyl ether type substances. Organic electrochemistry was used to elucidate the possible surface reaction mechanisms.

Antiedematogenic and antioxidant properties of high molecular weight protein sub-fraction of Calotropis procera latex in rat.

PubMed

Chaudhary, Priyanka; de Araújo Viana, Carolina; Ramos, Marcio V; Kumar, Vijay L

2015-03-01

The aim was to evaluate the effect of high molecular weight protein fraction of Calotropis procera latex on edema formation and oxidative stress in carrageenan-induced paw inflammation. A sub-plantar injection of carrageenan was given to induce edema in the hind paw of the rat. The inhibitory effect of high molecular weight protein fraction of C. procera latex was evaluated following intravenous administration (5 and 25 mg/kg body weight) and was compared with that of diclofenac given orally (5 mg/kg). The levels of reduced glutathione (GSH), thiobarbituric acid reactive substances (TBARS) and myeloperoxidase (MPO) were measured in the inflamed paw tissue at the end of the study. The high molecular weight protein fraction obtained from the latex of C. procera produced a dose-dependent inhibition of edema formation that was accompanied by normalization of levels of oxidative stress markers (GSH and TBARS) and MPO, a marker for neutrophils in the paw tissue. The high molecular weight protein fraction of C. procera latex ameliorates acute inflammation in the paw through its antioxidant effect.

Entanglement in miscible blends

NASA Astrophysics Data System (ADS)

Watanabe, Hiroshi

2010-03-01

The entanglement length Le of polymer chains (corresponding to the entanglement molecular weight Me) is not an intrinsic material parameter but changes with the interaction with surrounding chains. For miscible blends of cis-polyisoprene (PI) and poly(tert-butyl styrene) (PtBS), changes of Le on blending was examined. It turned out that the Le averaged over the number fractions of the Kuhn segments of the components (PI and PtBS) satisfactorily describes the viscoelastic behavior of pseudo-monodisperse blends in which the terminal relaxation time is the same for PI and PtBS.

Rapid and efficient hydrophilicity tuning of p53/mdm2 antagonists*

PubMed Central

Srivastava, Stuti; Beck, Barbara; Wang, Wei; Czarna, Anna; Holak, Tad A.; Dömling, Alexander

2009-01-01

The protein-protein interaction of p53 and mdm2 is an important anticancer target. The interface, however, is very hydrophobic and naturally results in very hydrophobic antagonists. We used the Orru three component reaction (O-3CR) along with a rapid and efficient, recently discovered amidation reaction to dramatically improve the water solubility of our recently discovered low molecular weight p53/mdm2 antagonists. Arrays of amides were synthesized with improved hydrophilicity and retainment and/or improvement of p53/mdm2 inhibitory activity. PMID:19548636

Separation of gases through gas enrichment membrane composites

DOEpatents

Swedo, R.J.; Kurek, P.R.

1988-07-19

Thin film composite membranes having as a permselective layer a film of a homopolymer of certain vinyl alkyl ethers are useful in the separation of various gases. Such homopolymers have a molecular weight of greater than 30,000 and the alkyl group of the vinyl alkyl monomer has from 4 to 20 carbon atoms with branching within the alkyl moiety at least at the carbon atom bonded to the ether oxygen or at the next adjacent carbon atom. These membranes show excellent hydrolytic stability, especially in the presence of acidic or basic gaseous components.

Separation of gases through gas enrichment membrane composites

DOEpatents

Swedo, Raymond J.; Kurek, Paul R.

1988-01-01

Thin film composite membranes having as a permselective layer a film of a homopolymer of certain vinyl alkyl ethers are useful in the separation of various gases. Such homopolymers have a molecular weight of greater than 30,000 and the alkyl group of the vinyl alkyl monomer has from 4 to 20 carbon atoms with branching within the alkyl moiety at least at the carbon atom bonded to the ether oxygen or at the next adjacent carbon atom. These membranes show excellent hydrolytic stability, especially in the presence of acidic or basic gaseous components.

Preparation of thin ceramic films via an aqueous solution route

DOEpatents

Pederson, Larry R.; Chick, Lawrence A.; Exarhos, Gregory J.

1989-01-01

A new chemical method of forming thin ceramic films has been developed. An aqueous solution of metal nitrates or other soluble metal salts and a low molecular weight amino acid is coated onto a substrate and pyrolyzed. The amino acid serves to prevent precipitation of individual solution components, forming a very viscous, glass-like material as excess water is evaporated. Using metal nitrates and glycine, the method has been demonstrated for zirconia with various levels of yttria stabilization, for lanthanum-strontium chromites, and for yttrium-barium-copper oxide superconductors on various substrates.

Endogenous pyrogen activity in human plasma after exercise.

PubMed

Cannon, J G; Kluger, M J

1983-05-06

Plasma obtained from human subjects after exercise and injected intraperitoneally into rats elevated rat rectal temperature and depressed plasma iron and zinc concentrations. The pyrogenic component was heat-denaturable and had an apparent molecular weight of 14,000 daltons. Human mononuclear leukocytes obtained after exercise and incubated in vitro released a factor into the medium that also elevated body temperature in rats and reduced trace metal concentrations. These results suggest that endogenous pyrogen, a protein mediator of fever and trace metal metabolism during infection, is released during exercise.

Catalysts and process for liquid hydrocarbon fuel production

DOEpatents

White, Mark G; Liu, Shetian

2014-12-09

The present invention provides a novel process and system in which a mixture of carbon monoxide and hydrogen synthesis gas, or syngas, is converted into hydrocarbon mixtures composed of high quality gasoline components, aromatic compounds, and lower molecular weight gaseous olefins in one reactor or step. The invention utilizes a novel molybdenum-zeolite catalyst in high pressure hydrogen for conversion, as well as a novel rhenium-zeolite catalyst in place of the molybdenum-zeolite catalyst, and provides for use of the novel catalysts in the process and system of the invention.

[Crosslinking sodium hyaluronate gel with different ratio of molecular weight for subcutaneous injection: animal experimental study and clinical trials subcutaneous injection].

PubMed

Ran, Weizhi; Wang, Xiaoli; Hu, Yuefei; Gao, Songying; Yang, Yahong; Sun, Jian; Sun, Shuming; Liu, Zhongmei; Wang, Jiangling

2015-05-01

To investigate the biocompatibility and degradation rate of crosslinking sodium hyaluronate gel with different ratio of molecular weight, so as to choose the effective, safe and totally degraded hyaluronate gel for aesthetic injection. (1) Compound colloid was formed by cross-linking the divinyl sulphone and sodium hyaluronate with different molecular weight (4 x 10(5), 8 x 10(5), 10 x 10(5), 12 x 10(5)). (2) Healthy level KM mice was randomly divided into two groups to receive hyaluronic acid gel or liquid injection. Each group was subdivided into three subgroup to receive hyaluronic acid with different molecular weight. The biocompatibility and degradation rate, of hyaluronate were observed at 7, 90, 180 days after injection. At the same time, different molecular weight of sodium hyaluronate gel is sealed or exposed respectively under the low temperature preservation to observe its natural degradation rate. (3) The most stable colloid was selected as aesthetic injector for volunteers to observe the aesthetic effect. The sodium hyaluronate gel with molecular of 4 x 10(5) was completely degraded 90 days later. The sodium hyaluronate gel with molecular of 8 x 10(5) was completely degraded 180 days later. The sodium hyaluronate gel with molecular of 10 x 10(5) was degraded to 90.0% after 180 days. The sodium hyaluronate liquid can be degraded completely within 7 days. The colloid could be kept for at least 12 months when sealed under low temperature, but was totally degraded when exposed for I d. Sodium hyaluronate gel with molecular 10 x 10(5) was confirmed to be kept for at least 6 months in animal experiment and clinical trials. Under the same condition of material ratio, the higher the molecular weight is, the lower the degradation rate is. But the liquidity of gel is not good for injection when molecular weight is too large. It suggests that Sodium hyaluronate gel with molecular 10 x 10(5) maybe the best choice in cosmetic injections.

Mild acetosolv process to fractionate bamboo for the biorefinery: structural and antioxidant properties of the dissolved lignin.

PubMed

Li, Ming-Fei; Sun, Shao-Ni; Xu, Feng; Sun, Run-Cang

2012-02-22

Fractionation of lignocellulosic material into its constitutive components is of vital importance for the production of biofuels as well as other value-added chemicals. The conventional acetosolv processes are mainly focused on the production of pulp from woody lignocelluloses. In this study, a mild acetosolv process was developed to fractionate bamboo under atmospheric pressure to obtain cellulosic pulp, water-soluble fraction, and acetic acid lignin. The structural features of the lignins obtained under various conditions were characterized with elemental analysis, sugar analysis, alkaline nitrobenzene oxidation, gel permeation chromatography (GPC), (1)H nuclear magnetic resonance ((1)H NMR), and heteronuclear single-quantum coherence (HSQC) spectroscopy. As compared to milled wood lignin (MWL) of bamboo, acetic acid lignins had low impurities (carbohydrates 2.48-4.56%) mainly due to the cleavage of linkages between lignin and carbohydrates. In addition, acetic acid lignins showed a low proportion of syringyl (S) units. Due to the cleavage of linkages between lignin units, acetic acid lignins had weight-average molecular weights ranging from 4870 to 5210 g/mol, less than half that of MWL (13000 g/mol). In addition, acetic acid lignins showed stronger antioxidant activity mainly due to the significant increase of free phenolic hydroxyls. The lignins obtained with such low impurities, high free phenolic hydroxyls, and medium molecular weights are promising feedstocks to replace petroleum chemicals.

Isolation and characterization of coagulant extracted from Moringa oleifera seed by salt solution.

PubMed

Okuda, T; Baes, A U; Nishijima, W; Okada, M

2001-02-01

It is known that M. oleifera contains a natural coagulant in the seeds. In our previous research, the method using salt water to extract the active coagulation component from M. oleifera seeds was developed and compared with the conventional method using water. In this research, the active coagulation component was purified from a NaCl solution crude extract of Moringa oleifera seeds. The active component was isolated and purified from the crude extract through a sequence of steps that included salting-out by dialysis, removal of lipids and carbohydrates by homogenization with acetone, and anion exchange. Specific coagulation activity of the active material increased up to 34 times more than the crude extract after the ion exchange. The active component was not the same as that of water extract. The molecular weight was about 3000 Da. The Lowry method and the phenol-sulfuric acid method indicated that the active component was neither protein nor polysaccharide. The optimum pH of the purified active component for coagulation of turbidity was pH 8 and above. Different from the conventional water extracts, the active component can be used for waters with low turbidity without increase in the dissolved organic carbon concentration.

Analysis of the low molecular weight fraction of serum by LC-dual ESI-FT-ICR mass spectrometry: precision of retention time, mass, and ion abundance.

PubMed

Johnson, Kenneth L; Mason, Christopher J; Muddiman, David C; Eckel, Jeanette E

2004-09-01

This study quantifies the experimental uncertainty for LC retention time, mass measurement precision, and ion abundance obtained from replicate nLC-dual ESI-FT-ICR analyses of the low molecular weight fraction of serum. We used ultrafiltration to enrich the < 10-kDa fraction of components from the high-abundance proteins in a pooled serum sample derived from ovarian cancer patients. The THRASH algorithm for isotope cluster detection was applied to five replicate nLC-dual ESI-FT-ICR chromatograms. A simple two-level grouping algorithm was applied to the more than 7000 isotope clusters found in each replicate and identified 497 molecular species that appeared in at least four of the replicates. In addition, a representative set of 231 isotope clusters, corresponding to 188 unique molecular species, were manually interpreted to verify the automated algorithm and to set its tolerances. For nLC retention time reproducibility, 95% of the 497 species had a 95% confidence interval of the mean of +/- 0.9 min or less without the use of chromatographic alignment procedures. Furthermore, 95% of the 497 species had a mass measurement precision of < or = 3.2 and < or = 6.3 ppm for internally and externally calibrated spectra, respectively. Moreover, 95% of replicate ion abundance measurements, covering an ion abundance range of approximately 3 orders of magnitude, had a coefficient of variation of less than 62% without using any normalization functions. The variability of ion abundance was independent of LC retention time, mass, and ion abundance quartile. These measures of analytical reproducibility establish a statistical rationale for differentiating healthy and disease patient populations for the elucidation of biomarkers in the low molecular fraction of serum. Copyright 2004 American Chemical Society

Improved synthesis with high yield and increased molecular weight of poly(alpha,beta-malic acid) by direct polycondensation.

PubMed

Kajiyama, Tetsuto; Kobayashi, Hisatoshi; Taguchi, Tetsushi; Kataoka, Kazunori; Tanaka, Junzo

2004-01-01

The development of synthetic biodegradable polymers, such as poly(alpha-hydroxy acid), is particularly important for constructing medical devices, including scaffolds and sutures, and has attracted growing interest in the biomedical field. Here, we report a novel approach to preparing high molecular weight poly(malic acid) (HMW--PMA) as a biodegradable and bioabsorbable water-soluble polymer. We investigated in detail the reaction conditions for the simple direct polycondensation of l-malic acid, including the reaction times, temperatures, and catalysts. The molecular weight of synthesized alpha,beta-PMA is dependent on both the reaction temperature and time. The optimum reaction condition to obtain alpha,beta-PMA by direct polycondensation using tin(II) chloride as a catalyst was thus determined to be 110 degrees C for 45 h with a molecular weight of 5300. The method for alpha,beta-PMA synthesis established here will facilitate production of alpha,beta-PMA of various molecular weights, which may have a potential utility as biomaterials.

Reorganization of low-molecular-weight fraction of plasma proteins in the annual cycle of cyprinidae.

PubMed

Andreeva, A M; Lamas, N E; Serebryakova, M V; Ryabtseva, I P; Bolshakov, V V

2015-02-01

Reorganization of the low-molecular-weight fraction of cyprinid plasma was analyzed using various electrophoretic techniques (disc electrophoresis, electrophoresis in polyacrylamide concentration gradient, in polyacrylamide with urea, and in SDS-polyacrylamide). The study revealed coordinated changes in the low-molecular-weight protein fractions with seasonal dynamics and related reproductive rhythms of fishes. We used cultured species of the Cyprinidae family with sequenced genomes for the detection of these interrelations in fresh-water and anadromous cyprinid species. The common features of organization of fish low-molecular-weight plasma protein fractions made it possible to make reliable identification of their proteins. MALDI mass-spectrometry analysis revealed the presence of the same proteins (hemopexin, apolipoproteins, and serpins) in the low-molecular-weight plasma fraction in wild species and cultured species with sequenced genomes (carp, zebrafish). It is found that the proteins of the first two classes are organized as complexes made of protein oligomers. Stoichiometry of these complexes changes in concordance with the seasonal and reproductive rhythms.

High-molecular-weight polymers for protein crystallization: poly-γ-glutamic acid-based precipitants

PubMed Central

Hu, Ting-Chou; Korczyńska, Justyna; Smith, David K.; Brzozowski, Andrzej Marek

2008-01-01

Protein crystallization has been revolutionized by the intro­duction of high-throughput technologies, which have led to a speeding up of the process while simultaneously reducing the amount of protein sample necessary. Nonetheless, the chemistry dimension of protein crystallization has remained relatively undeveloped. Most crystallization screens are based on the same set of precipitants. To address this shortcoming, the development of new protein precipitants based on poly-γ-­glutamic acid (PGA) polymers with different molecular-weight ranges is reported here: PGA-LM (low molecular weight) of ∼400 kDa and PGA-HM (high molecular weight) of >1000 kDa. It is also demonstrated that protein precipitants can be expanded further to polymers with much higher molecular weight than those that are currently in use. Furthermore, the modification of PGA-like polymers by covalent attachments of glucosamine substantially improved their solubility without affecting their crystallization properties. Some preliminary PGA-based screens are presented here. PMID:18703844

Effects of the Terminal Structure, Purity, and Molecular Weight of an Amorphous Conjugated Polymer on Its Photovoltaic Characteristics.

PubMed

Kuwabara, Junpei; Yasuda, Takeshi; Takase, Naoto; Kanbara, Takaki

2016-01-27

The photovoltaic characteristics of an amorphous polymer containing EDOT and fluorene units were investigated. In particular, the effects of the terminal structure, residual amount of Pd, and molecular weight were systematically investigated. Direct arylation polycondensation of EDOT followed by an established purification method readily afforded polymers with different terminal structures, Pd contents, and molecular weights. Of these factors, the terminal structure of the polymer was a crucial factor affecting the photovoltaic characteristics. For example, the polymer with a Br terminal had a PCE of 2.9% in bulk-heterojunction organic photovoltaics (BHJ OPVs) with a fullerene derivative, whereas the polymer without a Br terminal had a PCE of 4.6% in the same cell configuration. The decreased Pd residues and high molecular weights of the polymers increased the long-term stability of the devices. Moreover, BHJ OPVs containing the high-molecular-weight polymer could be fabricated with an environmentally friendly nonhalogenated solvent.

Immunomodulatory activity of polysaccharides isolated from Alchornea cordifolia

PubMed Central

Kouakou, Koffi; Schepetkin, Igor A.; Yapi, Ahoua; Kirpotina, Liliya N.; Jutila, Mark A.; Quinn, Mark T.

2013-01-01

Ethnopharmacological relevance Extracts of leaves from different species of the genus Alchornea have been used for centuries to treat a variety of medicinal problems in tropical Africa. However, little is known about the high-molecular weight active components conferring therapeutic properties to these extracts. Objective The aim of this study was to evaluate the immunomodulatory activity of polysaccharides isolated from the leaves of Alchornea cordifolia. Materials and methods Water-soluble polysaccharides from leaves of A. cordifolia were extracted and fractionated by DEAE-cellulose, Diaion HP-20, and size-exclusion chromatography. Molecular weight, sugar analysis, and other physical and chemical characterization of the fractions were performed. Immunomodulatory activity of the polysaccharide fractions was evaluated by determining their ability to induce monocyte/macrophage nitric oxide (NO) and cytokine production. Activation of mitogen activated protein kinases (MAPK) was also assessed using a phospho-MAPK array. Activation of nuclear factor κB (NF-κB) was measured using an alkaline phosphatase reporter gene assay in THP1-Blue monocytic cells. Results Six polysaccharide fractions from A. cordifolia were isolated. Fractions containing type II arabinogalactan had potent immunomodulatory activity. Particularly, the parent fraction AP-AU and its high-molecular weight sub-fraction AP-AU1 (average Mr was estimated to be 39.5 kDa) induced production of NO and cytokines [interleukin (IL)-1β, -6, -10, tumor necrosis factor (TNF)-α, and granulocyte macrophage-colony stimulating factor (GM-CSF)] in human peripheral blood mononuclear cells and human and murine monocyte/macrophages cell lines in vitro. Furthermore, treatment with AP-AU1 induced phosphorylation of Akt2, p38δ/p38γ, p70S6K1, RSK2, and mTOR, as well as stimulation of NF-κB transcriptional activity. Conclusion Our results provide a molecular basis to explain a portion of the beneficial therapeutic properties of water extracts from A. cordifolia leaves in traditional folk medicine of Africa. PMID:23291534

Immunomodulatory activity of polysaccharides isolated from Alchornea cordifolia.

PubMed

Kouakou, Koffi; Schepetkin, Igor A; Yapi, Ahoua; Kirpotina, Liliya N; Jutila, Mark A; Quinn, Mark T

2013-03-07

Extracts of leaves from different species of the genus Alchornea have been used for centuries to treat a variety of medicinal problems in tropical Africa. However, little is known about the high-molecular weight active components conferring therapeutic properties to these extracts. The aim of this study was to evaluate the immunomodulatory activity of polysaccharides isolated from the leaves of Alchornea cordifolia. Water-soluble polysaccharides from leaves of Alchornea cordifolia were extracted and fractionated by DEAE-cellulose, Diaion HP-20, and size-exclusion chromatography. Molecular weight, sugar analysis, and other physical and chemical characterization of the fractions were performed. Immunomodulatory activity of the polysaccharide fractions was evaluated by determining their ability to induce monocyte/macrophage nitric oxide (NO) and cytokine production. Activation of mitogen activated protein kinases (MAPK) was also assessed using a phospho-MAPK array. Activation of nuclear factor κB (NF-κB) was measured using an alkaline phosphatase reporter gene assay in THP1-Blue monocytic cells. Six polysaccharide fractions from Alchornea cordifolia were isolated. Fractions containing type II arabinogalactan had potent immunomodulatory activity. Particularly, the parent fraction AP-AU and its high-molecular weight sub-fraction AP-AU1 (average M(r) was estimated to be 39.5kDa) induced production of NO and cytokines [interleukin (IL)-1β, -6, -10, tumor necrosis factor (TNF)-α, and granulocyte-macrophage-colony stimulating factor (GM-CSF)] in human peripheral blood mononuclear cells and human and murine monocyte/macrophages cell lines in vitro. Furthermore, treatment with AP-AU1 induced phosphorylation of Akt2, p38δ/p38γ, p70S6K1, RSK2, and mTOR, as well as stimulation of NF-κB transcriptional activity. Our results provide a molecular basis to explain a portion of the beneficial therapeutic properties of water extracts from Alchornea cordifolia leaves in traditional folk medicine of Africa. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Liquid-State NMR Analysis of Nanocelluloses.

PubMed

King, Alistair W T; Mäkelä, Valtteri; Kedzior, Stephanie A; Laaksonen, Tiina; Partl, Gabriel J; Heikkinen, Sami; Koskela, Harri; Heikkinen, Harri A; Holding, Ashley J; Cranston, Emily D; Kilpeläinen, Ilkka

2018-04-11

Recent developments in ionic liquid electrolytes for cellulose or biomass dissolution has also allowed for high-resolution 1 H and 13 C NMR on very high molecular weight cellulose. This permits the development of advanced liquid-state quantitative NMR methods for characterization of unsubstituted and low degree of substitution celluloses, for example, surface-modified nanocelluloses, which are insoluble in all molecular solvents. As such, we present the use of the tetrabutylphosphonium acetate ([P 4444 ][OAc]):DMSO- d 6 electrolyte in the 1D and 2D NMR characterization of poly(methyl methacrylate) (PMMA)-grafted cellulose nanocrystals (CNCs). PMMA- g-CNCs was chosen as a difficult model to study, to illustrate the potential of the technique. The chemical shift range of [P 4444 ][OAc] is completely upfield of the cellulose backbone signals, avoiding signal overlap. In addition, application of diffusion-editing for 1 H and HSQC was shown to be effective in the discrimination between PMMA polymer graft resonances and those from low molecular weight components arising from the solvent system. The bulk ratio of methyl methacrylate monomer to anhydroglucose unit was determined using a combination of HSQC and quantitative 13 C NMR. After detachment and recovery of the PMMA grafts, through methanolysis, DOSY NMR was used to determine the average self-diffusion coefficient and, hence, molecular weight of the grafts compared to self-diffusion coefficients for PMMA GPC standards. This finally led to a calculation of both graft length and graft density using liquid-state NMR techniques. In addition, it was possible to discriminate between triads and tetrads, associated with PMMA tacticity, of the PMMA still attached to the CNCs (before methanolysis). CNC reducing end and sulfate half ester resonances, from sulfuric acid hydrolysis, were also assignable. Furthermore, other biopolymers, such as hemicelluloses and proteins (silk and wool), were found to be soluble in the electrolyte media, allowing for wider application of this method beyond just cellulose analytics.

Modeling of the phase equilibria of polystyrene in methylcyclohexane with semi-empirical quantum mechanical methods I.

PubMed

Wilczura-Wachnik, Hanna; Jónsdóttir, Svava Osk

2003-04-01

A method for calculating interaction parameters traditionally used in phase-equilibrium computations in low-molecular systems has been extended for the prediction of solvent activities of aromatic polymer solutions (polystyrene+methylcyclohexane). Using ethylbenzene as a model compound for the repeating unit of the polymer, the intermolecular interaction energies between the solvent molecule and the polymer were simulated. The semiempirical quantum chemical method AM1, and a method for sampling relevant internal orientations for a pair of molecules developed previously were used. Interaction energies are determined for three molecular pairs, the solvent and the model molecule, two solvent molecules and two model molecules, and used to calculated UNIQUAC interaction parameters, a(ij) and a(ji). Using these parameters, the solvent activities of the polystyrene 90,000 amu+methylcyclohexane system, and the total vapor pressures of the methylcyclohexane+ethylbenzene system were calculated. The latter system was compared to experimental data, giving qualitative agreement. Figure Solvent activities for the methylcylcohexane(1)+polystyrene(2) system at 316 K. Parameters aij (blue line) obtained with the AM1 method; parameters aij (pink line) from VLE data for the ethylbenzene+methylcyclohexane system. The abscissa is the polymer weight fraction defined as y2(x1)=(1mx1)M2/[x1M1+(1mx1)M2], where x1 is the solvent mole fraction and Mi are the molecular weights of the components.

Biochemical characterisation of urease from urease-positive thermophilic campylobacter (UPTC).

PubMed

Tazumi, A; Nakajima, T; Sekizuka, A; Arikawa, K; Nakanishi, S; Hayashi, K; Tasaki, E; Moore, J E; Millar, B C; Matsuda, M

2012-01-01

This study aims to characterise biochemically urease from an atypical Campylobacter lari, namely urease-positive thermophilic Campylobacter (UPTC). Urease was purified from cells of a Japanese UPTC isolate (CF89-12) using phenyl-Sepharose chromatography. Two protein components (estimates molecular masses 24 kDa and 61 kDa) were obtained that appeared to be structural proteins of urease (subunits A and B), and these were fractionated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (PAGE). The native molecular weight for the final purified UPTC urease was estimated to be approximately 186,000 Da which is close to the calculated molecular weight (182,738 Da) based on all six open reading frames of UPTC CF89-12 urease genes (ureA, B, E, F, G and H), as described previously. Moreover, an active band was observed on phenol red staining after a nondenaturing native PAGE of the crude extract from the UPTC cells. In addition, the purified urease of UPTC CF8912 showed enzyme activity over a broad pH range (pH 6-10), with maximal activity at pH 8.0. The urease was also stable against heat treatment, with almost no loss of enzyme activity seen following 60-min incubation at temperatures of 20-60 degrees C. Urease subunits A and B were identified immunologically by Western blot analysis with rabbit anti-urease alpha (A) and beta (B) raised against Helicobacter pylori.

Absorption and Fluorescence Properties of Chromophoric Dissolved Organic Matter Produced by Algae.

PubMed

Peng, Tong; Lu, Xiao-lan; Su, Rong-guo; Zhang, Dong-mei

2015-09-01

Four kinds of diatom (Chaetoceros curvisetus, Phaeodactylum tricornutum, Nitzschia closterium f. minutissima and Navicula halophile) and two kinds of dinoflagellates (Prorocentrum donghaiense and Gymnodinium) were cultured under laboratory conditions. Variations of optical properties of chromophoric dissolved organic matter (CDOM) were studied with absorption and fluorescence excitation-emission matrix spectroscopy(EEM) during growth of marine microalgae in incubation experiment. Absorption spectrum revealed absorption coefficient a(355) (CDOM absorption coefficients at 355 nm) of 6 kinds of marine microalgae above increased by 64.8%, 242.3%, 535.1%, 903.2%, 836% and 196.4%, respectively. Simultaneously, the absorption spectral slope (Sg), determined between 270 and 350 nm, representing the size of molecular weight of CDOM and humic-like composition, decreased by 8.7%, 34.6%, 39.4%, 53.1%, 46.7%, and 35.7%, respectively. Applying parallel factor analysis (PARAFAC) together with EEM got four components of CDOM: C1(Ex/Em=350(260) nm/450 nm), C2 (Ex/Em=260(430) nm/525 nm), C3 (Ex/Em=325 nm/400 nm) and C4(Ex/Em=275 nm/325 nm), which were relative to three humic-like and one protein-like fluorescent components of Nitzschia closterium f. minutissima and Navicula halophile. In incubation experiment, fluorescence intensity of these four components during growth of Nitzschia closterium f. minutissima increased by, respectively, 8.68, 24.9, 7.19 and 39.8 times, and those of Navicula halophile increased by 2.64, 0.07, 4.39 and 12.4 times, respectively. Significant relationships were found between the fluorescence intensity of four components of CDOM, a(355) and Sg. All results demonstrated that both content and molecular weight of CDOM produced by diatom and dinoflagellate studied in incubation experiment increased, but these two parameters changed more obviously of the diatom than those of dinoflagellate; the proportion of humic-like components in the composition of CDOM also increased clearly with the growth of marine microalgae, but protein-like fluorescent component had only a slow growth. Furthermore, the absorption spectrum of CDOM produced by different species of algae changed obviously and the relative composition fluorescence intensity of CDOM produced by different microalgae were found to vary among different composition from EEM, which suggested CDOM produced by different microalgae make quite different contributions to CDOM in natural seawater.

Chemical evolution of Macondo crude oil during laboratory degradation as characterized by fluorescence EEMs and hydrocarbon composition.

PubMed

Zhou, Zhengzhen; Liu, Zhanfei; Guo, Laodong

2013-01-15

The fluorescence EEM technique, PARAFAC modeling, and hydrocarbon composition were used to characterize oil components and to examine the chemical evolution and degradation pathways of Macondo crude oil under controlled laboratory conditions. Three major fluorescent oil components were identified, with Ex/Em maxima at 226/328, 262/315, and 244/366 nm, respectively. An average degradation half-life of ∼20 d was determined for the oil components based on fluorescence EEM and hydrocarbon composition measurements, showing a dynamic chemical evolution and transformation of the oil during degradation. Dispersants appeared to change the chemical characteristics of oil, to shift the fluorescence EEM spectra, and to enhance the degradation of low-molecular-weight hydrocarbons. Photochemical degradation played a dominant role in the transformation of oil components, likely an effective degradation pathway of oil in the water column. Results from laboratory experiments should facilitate the interpretation of field-data and provide insights for understanding the fate and transport of oil components in the Gulf of Mexico. Copyright © 2012 Elsevier Ltd. All rights reserved.

Increasing molecular weight parameters of a helical polymer through polymerization in a chiral solvent.

PubMed

Holder, Simon J; Achilleos, Mariliz; Jones, Richard G

2006-09-27

In this communication, we will demonstrate that polymerization in a chiral solvent can affect the molecular weight distribution of the product by perturbing the balance of the P and M helical screw senses of the growing chains. Specifically, for the Wurtz-type synthesis of polymethylphenylsilane (PMPS) in either (R) or (S)-limonene, the weight-average molecular weight of the products (average Mw = 80 000) was twice that of PMPS synthesized in (R/S)-limonene (average Mw = 39 200). Peturbation of the helical segmentation along the polymer chains leads to a reduction in the rate of occurrence of a key termination step. This the first time that a chiral solvent has been demonstrated to have such an effect on a polymerization process in affecting molecular weight parameters in contrast to affecting tacticity.

Production of low-molecular weight soluble yeast β-glucan by an acid degradation method.

PubMed

Ishimoto, Yuina; Ishibashi, Ken-Ichi; Yamanaka, Daisuke; Adachi, Yoshiyuki; Kanzaki, Ken; Iwakura, Yoichiro; Ohno, Naohito

2018-02-01

β-glucan is widely distributed in nature as water soluble and insoluble forms. Both forms of β-glucan are utilized in several fields, especially for functional foods. Yeast β-glucan is a medically important insoluble particle. Solubilization of yeast β-glucan may be valuable for improving functional foods and in medicinal industries. In the present study, we applied an acid degradation method to solubilize yeast β-glucan and found that β-glucan was effectively solubilized to low-molecular weight β-glucans by 45% sulfuric acid treatment at 20°C. The acid-degraded soluble yeast β-glucan (ad-sBBG) was further fractionated into a higher-molecular weight fraction (ad-sBBG-high) and a lower-molecular weight fraction (ad-sBBG-low). Since ad-sBBG-high contained mannan, while ad-sBBG-low contained it only scarcely, it was possible to prepare low-molecular weight soluble β-glucan with higher purity. In addition, ad-sBBG-low bound to dectin-1, which is an innate immunity receptor of β-glucan, and showed antagonistic activity against reactive oxygen production and cytokine synthesis by macrophages. Thus, this acid degradation method is an important procedure for generating immune-modulating, low-molecular weight, soluble yeast β-glucan. Copyright © 2017 Elsevier B.V. All rights reserved.

Retraction Note: Catalytic living ring-opening metathesis polymerization

NASA Astrophysics Data System (ADS)

Nagarkar, Amit A.; Kilbinger, Andreas F. M.

2018-05-01

We the authors are retracting this Article because of our failure to reproduce the molecular weight dispersities (PDI) shown in Fig. 4 using the chain-transfer agent described in the paper (CTA1). While the degenerate chain-transfer mechanism described in Fig. 3 is correct, the best molecular weight dispersities that could be reproduced with the chain-transfer agent shown in the Article are much larger (PDI > 2.0) than reported.We have since studied the kinetics of CTA1 in comparison with several other chain-transfer agents we are currently investigating and we now understand that the reactivity of CTA1 towards propagating ruthenium alkylidene complexes is very low. Very long monomer addition times would therefore have been necessary to gain control over the molecular weight distribution. Such long addition times would exceed the lifetime of the Grubbs catalyst in solution. Faster addition of the monomer has since repeatedly been shown to broaden the molecular weight dispersity.Additionally, the best chain-transfer agents we are currently investigating are orders of magnitude more reactive than CTA1 but give broader molecular weight dispersities than reported in Fig. 4. Molecular weight and dispersity control as shown in Fig. 4 is therefore an inappropriate claim for CTA1.The authors deeply regret these errors and apologize to the community.

Vapor-pressure osmometric study of the molecular weight and aggregation tendency of a reference-soil fulvic acid

USGS Publications Warehouse

Marinsky, J.A.; Reddy, M.M.

1990-01-01

The molecular weight and aggregation tendency of a reference-soil fulvic acid in Armadale horizon Bh were determined by vapor-pressure osmometry using tetrahydrofuran and water as solvents. With tetrahydrofuran, number-average molecular weight values of 767 ?? 34 and 699 ?? 8 daltons were obtained from two separate sets of measurements. Two sets of measurements with water also yielded values within this range (754 ?? 70 daltons) provided that the fulvic acid concentration in water did not exceed 7 mg ml-1; at higher concentrations (9.1-13.7 mg ml-1) a number-average molecular weight of 956 ?? 25 daltons was resolved, providing evidence of molecular aggregation. Extension of these studies to 80% neutralized fulvic acid showed that a sizeable fraction of the sodium counter ion is not osmotically active.

QuBiLS-MAS, open source multi-platform software for atom- and bond-based topological (2D) and chiral (2.5D) algebraic molecular descriptors computations.

PubMed

Valdés-Martiní, José R; Marrero-Ponce, Yovani; García-Jacas, César R; Martinez-Mayorga, Karina; Barigye, Stephen J; Vaz d'Almeida, Yasser Silveira; Pham-The, Hai; Pérez-Giménez, Facundo; Morell, Carlos A

2017-06-07

In previous reports, Marrero-Ponce et al. proposed algebraic formalisms for characterizing topological (2D) and chiral (2.5D) molecular features through atom- and bond-based ToMoCoMD-CARDD (acronym for Topological Molecular Computational Design-Computer Aided Rational Drug Design) molecular descriptors. These MDs codify molecular information based on the bilinear, quadratic and linear algebraic forms and the graph-theoretical electronic-density and edge-adjacency matrices in order to consider atom- and bond-based relations, respectively. These MDs have been successfully applied in the screening of chemical compounds of different therapeutic applications ranging from antimalarials, antibacterials, tyrosinase inhibitors and so on. To compute these MDs, a computational program with the same name was initially developed. However, this in house software barely offered the functionalities required in contemporary molecular modeling tasks, in addition to the inherent limitations that made its usability impractical. Therefore, the present manuscript introduces the QuBiLS-MAS (acronym for Quadratic, Bilinear and N-Linear mapS based on graph-theoretic electronic-density Matrices and Atomic weightingS) software designed to compute topological (0-2.5D) molecular descriptors based on bilinear, quadratic and linear algebraic forms for atom- and bond-based relations. The QuBiLS-MAS module was designed as standalone software, in which extensions and generalizations of the former ToMoCoMD-CARDD 2D-algebraic indices are implemented, considering the following aspects: (a) two new matrix normalization approaches based on double-stochastic and mutual probability formalisms; (b) topological constraints (cut-offs) to take into account particular inter-atomic relations; (c) six additional atomic properties to be used as weighting schemes in the calculation of the molecular vectors; (d) four new local-fragments to consider molecular regions of interest; (e) number of lone-pair electrons in chemical structure defined by diagonal coefficients in matrix representations; and (f) several aggregation operators (invariants) applied over atom/bond-level descriptors in order to compute global indices. This software permits the parallel computation of the indices, contains a batch processing module and data curation functionalities. This program was developed in Java v1.7 using the Chemistry Development Kit library (version 1.4.19). The QuBiLS-MAS software consists of two components: a desktop interface (GUI) and an API library allowing for the easy integration of the latter in chemoinformatics applications. The relevance of the novel extensions and generalizations implemented in this software is demonstrated through three studies. Firstly, a comparative Shannon's entropy based variability study for the proposed QuBiLS-MAS and the DRAGON indices demonstrates superior performance for the former. A principal component analysis reveals that the QuBiLS-MAS approach captures chemical information orthogonal to that codified by the DRAGON descriptors. Lastly, a QSAR study for the binding affinity to the corticosteroid-binding globulin using Cramer's steroid dataset is carried out. From these analyses, it is revealed that the QuBiLS-MAS approach for atom-pair relations yields similar-to-superior performance with regard to other QSAR methodologies reported in the literature. Therefore, the QuBiLS-MAS approach constitutes a useful tool for the diversity analysis of chemical compound datasets and high-throughput screening of structure-activity data.

Post-exercise ingestion of a unique, high molecular weight glucose polymer solution improves performance during a subsequent bout of cycling exercise.

PubMed

Stephens, Francis B; Roig, Marc; Armstrong, Gerald; Greenhaff, Paul L

2008-01-15

The aim of the present study was to determine the effect of post-exercise ingestion of a unique, high molecular weight glucose polymer solution, known to augment gastric emptying and post-exercise muscle glycogen re-synthesis, on performance during a subsequent bout of intense exercise. On three randomized visits, eight healthy men cycled to exhaustion at 73.0% (s = 1.3) maximal oxygen uptake (90 min, s = 15). Immediately after this, participants consumed a one-litre solution containing sugar-free flavoured water (control), 100 g of a low molecular weight glucose polymer or 100 g of a very high molecular weight glucose polymer, and rested on a bed for 2 h. After recovery, a 15-min time-trial was performed on a cycle ergometer, during which work output was determined. Post-exercise ingestion of the very high molecular weight glucose polymer solution resulted in faster and greater increases in blood glucose (P < 0.001) and serum insulin (P < 0.01) concentrations than the low molecular weight glucose polymer solution, and greater work output during the 15-min time-trial (164.1 kJ, s = 21.1) than both the sugar-free flavoured water (137.5 kJ, s = 24.2; P < 0.05) and the low molecular weight glucose polymer (149.4 kJ, s = 21.8; P < 0.05) solutions. These findings could be of practical importance for athletes wishing to optimize performance by facilitating rapid re-synthesis of the muscle glycogen store during recovery following prolonged sub-maximal exercise.

A log-normal distribution model for the molecular weight of aquatic fulvic acids

USGS Publications Warehouse

Cabaniss, S.E.; Zhou, Q.; Maurice, P.A.; Chin, Y.-P.; Aiken, G.R.

2000-01-01

The molecular weight of humic substances influences their proton and metal binding, organic pollutant partitioning, adsorption onto minerals and activated carbon, and behavior during water treatment. We propose a lognormal model for the molecular weight distribution in aquatic fulvic acids to provide a conceptual framework for studying these size effects. The normal curve mean and standard deviation are readily calculated from measured M(n) and M(w) and vary from 2.7 to 3 for the means and from 0.28 to 0.37 for the standard deviations for typical aquatic fulvic acids. The model is consistent with several types of molecular weight data, including the shapes of high- pressure size-exclusion chromatography (HP-SEC) peaks. Applications of the model to electrostatic interactions, pollutant solubilization, and adsorption are explored in illustrative calculations.The molecular weight of humic substances influences their proton and metal binding, organic pollutant partitioning, adsorption onto minerals and activated carbon, and behavior during water treatment. We propose a log-normal model for the molecular weight distribution in aquatic fulvic acids to provide a conceptual framework for studying these size effects. The normal curve mean and standard deviation are readily calculated from measured Mn and Mw and vary from 2.7 to 3 for the means and from 0.28 to 0.37 for the standard deviations for typical aquatic fulvic acids. The model is consistent with several type's of molecular weight data, including the shapes of high-pressure size-exclusion chromatography (HP-SEC) peaks. Applications of the model to electrostatic interactions, pollutant solubilization, and adsorption are explored in illustrative calculations.

A single center retrospective cohort study comparing low-molecular-weight heparins to direct oral anticoagulants for the treatment of venous thromboembolism in patients with cancer - A real world experience.

PubMed

Phelps, Megan K; Wiczer, Tracy E; Erdeljac, H Paige; Van Deusen, Kelsey R; Porter, Kyle; Philips, Gary; Wang, Tzu-Fei

2018-01-01

Introduction Low-molecular-weight heparins are the standard treatment for cancer-associated thrombosis. Recently, direct oral anticoagulants are a new option for thrombosis treatment; however, data supporting the use of direct oral anticoagulants for cancer-associated thrombosis are limited. Objectives The primary objective of this study was to determine the rate of recurrent cancer-associated thrombosis and major bleeding within 6 months of starting either low-molecular-weight heparin or direct oral anticoagulant for treatment of cancer-associated thrombosis. Secondary objectives were to determine the rates of clinically relevant-non-major bleeding and all-cause mortality. Patients/methods This is a retrospective cohort study including adults with cancer-associated thrombosis treated with low-molecular-weight heparin or direct oral anticoagulant between 2010 and 2016 at the Ohio State University. Medical records were reviewed for 6 months after initiation of anticoagulation or until the occurrence of recurrent cancer-associated thrombosis, major bleeding, cessation of anticoagulation of interest, or death, whichever occurred first. Results Four hundred and eighty patients were included (290 low-molecular-weight heparin and 190 direct oral anticoagulant). Patients treated with direct oral anticoagulant were found to carry "lower risk" features including cancer with lower VTE risk and lower rate of metastatic disease. After adjustment for baseline differences, there was no significant difference in the rate of recurrent cancer-associated thrombosis (7.2% low-molecular-weight heparin vs 6.3% direct oral anticoagulant, p = 0.71) or major bleeding (7.6% low-molecular-weight heparin vs 2.6% direct oral anticoagulant, p = 0.08). Conclusions Our study demonstrates that in a select population of cancer patients with VTE, direct oral anticoagulant use can be as effective and safe compared to the standard therapy with low-molecular-weight heparin.

Characterization and distribution of polycyclic aromatic hydrocarbon contaminations in surface sediment and water from Gao-ping River, Taiwan.

PubMed

Doong, Ruey-An; Lin, Yu-Tin

2004-04-01

The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in water and sediment samples collected from 12 locations in Gao-ping River, Taiwan were analyzed. Molecular ratios and principal component analysis (PCA) were used to characterize the possible pollution sources. Concentrations of total 16 PAHs (SigmaPAHs) in water samples ranged from below method detection limits (

High molecular weight of polysaccharides from Hericium erinaceus against amyloid beta-induced neurotoxicity.

PubMed

Cheng, Jai-Hong; Tsai, Chia-Ling; Lien, Yi-Yang; Lee, Meng-Shiou; Sheu, Shyang-Chwen

2016-06-07

Hericium erinaceus (HE) is a well-known mushroom in traditional Chinese food and medicine. HE extracts from the fruiting body and mycelia not only exhibit immunomodulatory, antimutagenic and antitumor activity but also have neuroprotective properties. Here, we purified HE polysaccharides (HEPS), composed of two high molecular weight polysaccharides (1.7 × 10(5) Da and 1.1 × 10(5) Da), and evaluated their protective effects on amyloid beta (Aβ)-induced neurotoxicity in rat pheochromocytoma PC12 cells. HEPS were prepared and purified using a 95 % ethanol extraction method. The components of HEPS were analyzed and the molecular weights of the polysaccharides were determined using high-pressure liquid chromatography (HPLC). The neuroprotective effects of the polysaccharides were evaluated through a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and an MTT assay and by quantifying reactive oxygen species (ROS) and mitochondrial membrane potentials (MMP) of Aβ-induced neurotoxicity in cells. Our results showed that 250 μg/ml HEPS was harmless and promoted cell viability with 1.2 μM Aβ treatment. We observed that the free radical scavenging rate exceeded 90 % when the concentration of HEPS was higher than 1 mg/mL in cells. The HEPS decreased the production of ROS from 80 to 58 % in a dose-dependent manner. Cell pretreatment with 250 μg/mL HEPS significantly reduced Aβ-induced high MMPs from 74 to 51 % and 94 to 62 % at 24 and 48 h, respectively. Finally, 250 μg/mL of HEPS prevented Aβ-induced cell shrinkage and nuclear degradation of PC12 cells. Our results demonstrate that HEPS exhibit antioxidant and neuroprotective effects on Aβ-induced neurotoxicity in neurons.

The removal of organic precursors of DBPs during three advanced water treatment processes including ultrafiltration, biofiltration, and ozonation.

PubMed

Zha, Xiao-Song; Ma, Lu-Ming; Wu, Jin; Liu, Yan

2016-08-01

The removal efficiency of organic matter, the formation potential of trihalomethanes (THMFP), and the formation potential of haloacetic acids (HAAFP) in each unit of three advanced treatment processes were investigated in this paper. The molecular weight distribution and the components of organic matter in water samples were also determined to study the transformation of organic matter during these advanced treatments. Low-molecular-weight matter was the predominant fraction in raw water, and it could not be removed effectively by ultrafiltration and biofiltration. The dominant species of disinfection by-product formation potential (DBPFP) in raw water were chloroform and monochloroacetic acid (MCAA), with average concentrations of 107.3 and 125.9 μg/L, respectively. However, the formation potential of chloroform and MCAA decreased to 36.2 and 11.5 μg/L after ultrafiltration. Similarly, biological pretreatment obtained high removal efficiency for DBPFP. The total THMFP decreased from 173.8 to 81.8 μg/L, and the total HAAFP decreased from 211.9 to 84.2 μg/L. Separate ozonation had an adverse effect on DBPFP, especially for chlorinated HAAFP. Numerous low-molecular-weight compounds such as aldehydes, ketones, and alcohols were generated during the ozonation, which have been proven to be important precursors of HAAs. However, the ozonation/biological activated carbon (BAC) combined process had a better removal efficiency for DBPFP. The total DBPFP decreased remarkably from 338.7 to 113.3 μg/L after the O3/BAC process, far below the separated BAC of process B (189.1 μg/L).

Analyzing the influence of PEG molecular weight on the separation of PEGylated gold nanoparticles by asymmetric-flow field-flow fractionation.

PubMed

Hansen, Matthew; Smith, Mackensie C; Crist, Rachael M; Clogston, Jeffrey D; McNeil, Scott E

2015-11-01

Polyethylene glycol (PEG) is an important tool for increasing the biocompatibility of nanoparticle therapeutics. Understanding how these potential nanomedicines will react after they have been introduced into the bloodstream is a critical component of the preclinical evaluation process. Hence, it is paramount that better methods for separating, characterizing, and analyzing these complex and polydisperse formulations are developed. We present a method for separating nominal 30-nm gold nanoparticles coated with various molecular weight PEG moieties that uses only phosphate-buffered saline as the mobile phase, without the need for stabilizing surfactants. The optimized asymmetric-flow field-flow fractionation technique using in-line multiangle light scattering, dynamic light scattering, refractive index, and UV-vis detectors allowed successful separation and detection of a mixture of nanoparticles coated with 2-, 5-, 10-, and 20-kDa PEG. The particles coated with the larger PEG species (10 and 20 kDa) were eluted at times significantly earlier than predicted by field-flow fractionation theory. This was attributed to a lower-density PEG shell for the higher molecular weight PEGylated nanoparticles, which allows a more fluid PEG surface that can be greater influenced by external forces. Hence, the apparent particle hydrodynamic size may fluctuate significantly depending on the overall density of the stabilizing surface coating when an external force is applied. This has considerable implications for PEGylated nanoparticles intended for in vivo application, as nanoparticle size is important for determining circulation times, accumulation sites, and routes of excretion, and highlights the importance and value of the use of secondary size detectors when one is working with complex samples in asymmetric-flow field-flow fractionation.

Concentration of polychlorinated biphenyl (PCB) congeners in the muscle of Clarias gariepinus and sediment from inland rivers of southwestern Nigeria and estimated potential human health consequences.

PubMed

Adeogun, Aina O; Chukwuka, Azubuike V; Okoli, Chukwunonso P; Arukwe, Augustine

2016-01-01

The distributions of polychlorinated biphenyl (PCB) congeners were determined in sediment and muscle of the African sharptooth catfish (Clarias gariepinus) from the Ogun and Ona rivers, southwest Nigeria. In addition, the effect of PCB congeners on condition factor (CF) and associated human health risk was assessed using muscle levels for a noncarcinogenic hazard quotient (HQ) calculation. Elevated concentrations of high-molecular-weight (HMW) PCB congeners were detected in sediment and fish downstream of discharge points of both rivers. A significant reduction in fish body weight and CF was observed to correlate with high PCB congener concentrations in the Ona River. A principal component (PC) biplot revealed significant site-related PCB congener distribution patterns for HMW PCB in samples from the Ogun River (71.3%), while the Ona River (42.6%) showed significant PCB congener patterns for low-molecular-weight (LMW) congeners. Biota-sediment accumulation factor (BSAF) was higher downstream for both rivers, presenting PCB congener-specific accumulation patterns in the Ona River. Significant decreases in fish body weight, length and CF were observed downstream compared to upstream in the Ona River. The non-carcinogenic HQ of dioxin-like congener 189 downstream in both rivers exceeded the HQ = 1 threshold for children and adults for both the Ogun and Ona rivers. Overall, our results suggest that industrial discharges contribute significantly to PCB inputs into these rivers, with potential for significant health implications for neighboring communities that utilize these rivers for fishing and other domestic purposes.

Modeling the relationship between body weight and energy intake: A molecular diffusion-based approach

PubMed Central

2012-01-01

Background 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. Results 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. Conclusions In conclusion, this model based on molecular diffusion provides a new insight into the body weight mechanisms. Reviewers This article was reviewed by Dr. Cabral Balreira (nominated by Dr. Peter Olofsson), Prof. Yang Kuang and Dr. Chao Chen. PMID:22742862

Evaluation of a Viscosity-Molecular Weight Relationship.

ERIC Educational Resources Information Center

Mathias, Lon J.

1983-01-01

Background information, procedures, and results are provided for a series of graduate/undergraduate polymer experiments. These include synthesis of poly(methylmethacrylate), viscosity experiment (indicating large effect even small amounts of a polymer may have on solution properties), and measurement of weight-average molecular weight by light…

Determination of the linear coefficient of thermal expansion in polymer films at the nanoscale: influence of the composition of EVA copolymers and the molecular weight of PMMA.

PubMed

González-Benito, J; Castillo, E; Cruz-Caldito, J F

2015-07-28

Nanothermal-expansion of poly(ethylene-co-vinylacetate), EVA, and poly(methyl methacrylate), PMMA, in the form of films was measured to finally obtain linear coefficients of thermal expansion, CTEs. The simple deflection of a cantilever in an atomic force microscope, AFM, was used to monitor thermal expansions at the nanoscale. The influences of: (a) the structure of EVA in terms of its composition (vinylacetate content) and (b) the size of PMMA chains in terms of the molecular weight were studied. To carry out this, several polymer samples were used, EVA copolymers with different weight percents of the vinylacetate comonomer (12, 18, 25 and 40%) and PMMA polymers with different weight average molecular weights (33.9, 64.8, 75.600 and 360.0 kg mol(-1)). The dependencies of the vinyl acetate weight fraction of EVA and the molecular weight of PMMA on their corresponding CTEs were analyzed to finally explain them using new, intuitive and very simple models based on the rule of mixtures. In the case of EVA copolymers a simple equation considering the weighted contributions of each comonomer was enough to estimate the final CTE above the glass transition temperature. On the other hand, when the molecular weight dependence is considered the free volume concept was used as novelty. The expansion of PMMA, at least at the nanoscale, was well and easily described by the sum of the weighted contributions of the occupied and free volumes, respectively.

Gel filtration of sialoglycoproteins.

PubMed Central

Alhadeff, J A

1978-01-01

The role of sialic acid in the gel-filtration behaviour of sialoglycoproteins was investigated by using the separated isoenzymes of purified human liver alpha-L-fucosidase and several other well-known sialic acid-containing glycoproteins (fetuin, alpha1-acid glycoprotein, thyroglobulin and bovine submaxillary mucin). For each glycoprotein studied, gel filtration of its desialylated derivative gave an apparent molecular weights much less than that expected just from removal of sialic acid. For the lower-molecular-weight glycoproteins (fetuin and alpha1-acid glyocprotein), gel filtration of the sialylated molecules led to apparent molecular weights much larger than the known values. The data indicate that gel filtration cannot be used for accurately determining the molecular weights of at least some sialoglycoproteins. Images Fig. 1. PMID:356853

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

PubMed Central

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

Polyimide molding powder, coating, adhesive, and matrix resin

NASA Technical Reports Server (NTRS)

St.clair, Terry L. (Inventor); Progar, Donald J. (Inventor)

1992-01-01

The invention is a polyimide prepared from 3,4'-oxydianiline (3,4'-ODA) and 4,4'-oxydiphthalic anhydride (ODPA), in 2-methoxyethyl ether (diglyme). The polymer was prepared in ultra high molecular weight and in a controlled molecular weight form which has a 2.5 percent offset in stoichiometry (excess diamine) with a 5.0 percent level of phthalic anhydride as an endcap. This controlled molecular weight form allows for greatly improved processing of the polymer for moldings, adhesive bonding, and composite fabrication. The higher molecular weight version affords tougher films and coatings. The overall polymer structure groups in the dianhydride, the diamine, and a metal linkage in the diamine affords adequate flow properties for making this polymer useful as a molding powder, adhesive, and matrix resin.

A study of physical properties of ODPA-p-PDA polyimide films

NASA Technical Reports Server (NTRS)

Singh, Jag J.; Eftekhari, Abe; St.clair, Terry L.

1990-01-01

Physical properties were investigated of ODPA-p-PDA polyimide films, including their lower molecular weight versions with phthalimide endcaps. Free volume, determined by low energy positron annihilation in the test films, was the major parameter of interest since all other physical properties are ostensibly related to it. It affects the dielectric constant as well as the saturation moisture pickup of the test films. An empirical relation was developed between the free volume and molecular weight of the test films, comparable to the Mark-Houwink relation between the polymer solution viscosity and the molecular weight. Development of such a relation constitutes a unique achievement since it enables researchers to estimate the molecular weight of an intractable polymer in solid state for the first time.

Summary of GPC/DV results for space exposed poly(arylene ether phosphine oxide)s

NASA Technical Reports Server (NTRS)

Siochi, Emilie

1995-01-01

Gel Permeation Chromatography (GPC) was used to analyze poly(arylene ether phosphine oxide)s whose backbones were identical except for the ketone content and placement. These samples were exposed to low Earth orbit environment (predominantly atomic oxygen) on space shuttle flights. The materials and their unexposed controls were then characterized by GPC to investigate the effect of atomic oxygen on the molecular weight distributions. Analysis of the soluble portion of the samples revealed that there was significant loss of high molecular weight species. The presence of insoluble material also suggested that crosslinking was induced by the atomic oxygen exposure and that this very likely occurred at the high molecular weight portion of the molecular weight distribution.

Augmenting Microarray Data with Literature-Based Knowledge to Enhance Gene Regulatory Network Inference

PubMed Central

Kilicoglu, Halil; Shin, Dongwook; Rindflesch, Thomas C.

2014-01-01

Gene regulatory networks are a crucial aspect of systems biology in describing molecular mechanisms of the cell. Various computational models rely on random gene selection to infer such networks from microarray data. While incorporation of prior knowledge into data analysis has been deemed important, in practice, it has generally been limited to referencing genes in probe sets and using curated knowledge bases. We investigate the impact of augmenting microarray data with semantic relations automatically extracted from the literature, with the view that relations encoding gene/protein interactions eliminate the need for random selection of components in non-exhaustive approaches, producing a more accurate model of cellular behavior. A genetic algorithm is then used to optimize the strength of interactions using microarray data and an artificial neural network fitness function. The result is a directed and weighted network providing the individual contribution of each gene to its target. For testing, we used invasive ductile carcinoma of the breast to query the literature and a microarray set containing gene expression changes in these cells over several time points. Our model demonstrates significantly better fitness than the state-of-the-art model, which relies on an initial random selection of genes. Comparison to the component pathways of the KEGG Pathways in Cancer map reveals that the resulting networks contain both known and novel relationships. The p53 pathway results were manually validated in the literature. 60% of non-KEGG relationships were supported (74% for highly weighted interactions). The method was then applied to yeast data and our model again outperformed the comparison model. Our results demonstrate the advantage of combining gene interactions extracted from the literature in the form of semantic relations with microarray analysis in generating contribution-weighted gene regulatory networks. This methodology can make a significant contribution to understanding the complex interactions involved in cellular behavior and molecular physiology. PMID:24921649

Augmenting microarray data with literature-based knowledge to enhance gene regulatory network inference.

PubMed

Chen, Guocai; Cairelli, Michael J; Kilicoglu, Halil; Shin, Dongwook; Rindflesch, Thomas C

2014-06-01

Gene regulatory networks are a crucial aspect of systems biology in describing molecular mechanisms of the cell. Various computational models rely on random gene selection to infer such networks from microarray data. While incorporation of prior knowledge into data analysis has been deemed important, in practice, it has generally been limited to referencing genes in probe sets and using curated knowledge bases. We investigate the impact of augmenting microarray data with semantic relations automatically extracted from the literature, with the view that relations encoding gene/protein interactions eliminate the need for random selection of components in non-exhaustive approaches, producing a more accurate model of cellular behavior. A genetic algorithm is then used to optimize the strength of interactions using microarray data and an artificial neural network fitness function. The result is a directed and weighted network providing the individual contribution of each gene to its target. For testing, we used invasive ductile carcinoma of the breast to query the literature and a microarray set containing gene expression changes in these cells over several time points. Our model demonstrates significantly better fitness than the state-of-the-art model, which relies on an initial random selection of genes. Comparison to the component pathways of the KEGG Pathways in Cancer map reveals that the resulting networks contain both known and novel relationships. The p53 pathway results were manually validated in the literature. 60% of non-KEGG relationships were supported (74% for highly weighted interactions). The method was then applied to yeast data and our model again outperformed the comparison model. Our results demonstrate the advantage of combining gene interactions extracted from the literature in the form of semantic relations with microarray analysis in generating contribution-weighted gene regulatory networks. This methodology can make a significant contribution to understanding the complex interactions involved in cellular behavior and molecular physiology.

An agarose gel electrophoretic method for analysis of hyaluronan molecular weight distribution.

PubMed

Lee, H G; Cowman, M K

1994-06-01

An electrophoretic method is described for determining the molecular weight distribution of hyaluronan (HA). The method involves separation of HA by electrophoresis on a 0.5% agarose gel, followed by detection of HA using the cationic dye Stains-All (3,3'-dimethyl-9-methyl-4,5,4'5'-dibenzothiacarbocyanine). The recommended sample load is 7 micrograms. Calibration of the method with HA standards of known molecular weight has established a linear relationship between electrophoretic mobility and the logarithm of the weight-average molecular weight over the range of approximately 0.2-6 x 10(6). The separated HA pattern may also be visualized after electrotransfer of HA from the agarose gel to a nylon membrane. The membrane may be stained with the dye alcian blue. Alternatively, specific detection of HA from impure samples can be achieved by probing the nylon membrane with biotin-labeled HA-binding protein and subsequent interaction with a streptavidin-linked gold reagent and silver staining for amplification. The electrophoretic method was used to analyze HA in two different liquid connective tissues. Normal human knee joint synovial fluid showed a narrow HA molecular weight distribution, with a peak at 6-7 x 10(6). Owl monkey vitreous HA also showed a narrow molecular weight distribution, with a peak at 5-6 x 10(6). These results agree well with available published data and indicate the applicability of the method to the analysis of impure HA samples which may be available in limited amounts.