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

Science.gov (United States)

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.

High Molecular Weight Polymers in the New Chemicals Program

Science.gov (United States)

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

Weight preoccupation as a function of observed physical attractiveness: ethnic differences among normal-weight adolescent females.

Science.gov (United States)

Colabianchi, Natalie; Ievers-Landis, Carolyn E; Borawski, Elaine A

2006-09-01

To examine the association between observer ratings of physical attractiveness and weight preoccupation for female adolescents, and to explore any ethnic differences between Caucasian, African-American, and Hispanic females. Normal-weight female adolescents who had participated in the National Longitudinal Study of Adolescent Health in-home Wave II survey were included (n = 4,324). Physical attractiveness ratings were made in vivo by interviewers. Using logistic regression models stratified by ethnicity, the associations between observer-rated attractiveness and weight preoccupation were examined after controlling for demographics, measured body mass index (BMI) and psychosocial factors. Caucasian female adolescents perceived as being more attractive reported significantly greater weight preoccupation compared with those rated as being less attractive. Observed attractiveness did not relate to weight preoccupation among African-American or Hispanic youth when controlling for other factors. For Caucasian female adolescents, being perceived by others as more attractive may be a risk factor for disordered eating.

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

DEFF Research Database (Denmark)

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

2008-01-01

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

Treatment of PCR products with exonuclease I and heat-labile alkaline phosphatase improves the visibility of combined bisulfite restriction analysis

International Nuclear Information System (INIS)

Watanabe, Kousuke; Emoto, Noriko; Sunohara, Mitsuhiro; Kawakami, Masanori; Kage, Hidenori; Nagase, Takahide; Ohishi, Nobuya; Takai, Daiya

2010-01-01

Research highlights: → Incubating PCR products at a high temperature causes smears in gel electrophoresis. → Smears interfere with the interpretation of methylation analysis using COBRA. → Treatment with exonuclease I and heat-labile alkaline phosphatase eliminates smears. → The elimination of smears improves the visibility of COBRA. -- Abstract: DNA methylation plays a vital role in the regulation of gene expression. Abnormal promoter hypermethylation is an important mechanism of inactivating tumor suppressor genes in human cancers. Combined bisulfite restriction analysis (COBRA) is a widely used method for identifying the DNA methylation of specific CpG sites. Here, we report that exonuclease I and heat-labile alkaline phosphatase can be used for PCR purification for COBRA, improving the visibility of gel electrophoresis after restriction digestion. This improvement is observed when restriction digestion is performed at a high temperature, such as 60 o C or 65 o C, with BstUI and TaqI, respectively. This simple method can be applied instead of DNA purification using spin columns or phenol/chloroform extraction. It can also be applied to other situations when PCR products are digested by thermophile-derived restriction enzymes, such as PCR restriction fragment length polymorphism (RFLP) analysis.

Do weight management programmes delivered at professional football clubs attract and engage high risk men? A mixed-methods study.

Science.gov (United States)

Hunt, Kate; Gray, Cindy M; Maclean, Alice; Smillie, Susan; Bunn, Christopher; Wyke, Sally

2014-01-21

The prevalence of obesity in men in the UK is amongst the highest in Europe but men are less likely than women to use existing weight loss programmes. Developing weight management programmes which are appealing and acceptable to men is a public health priority. Football Fans in Training (FFIT), a men-only weight management programme delivered to groups of men at top professional football clubs, encourages men to lose weight by working with, not against, cultural ideals of masculinity. To inform further development of interventions in football club settings, the current study explored who is attracted to FFIT and why overweight/obese men choose to take part. A mixed-methods study analysing baseline data on 747 men aged 35-65 years with BMI ≥ 28 kg/m2 who were participants in a randomised controlled trial of FFIT, and data from 13 focus group discussions with 63 men who had attended the programme. Objectively-measured mean body mass index was 35.3 kg/m2 (sd 4.9). Overall over 90% of participants were at very high or extremely high risk of future ill-health. Around three-quarters of participants in all age groups were at 'very high' risk of type 2 diabetes, hypertension and cardiovascular disease (72%, 73% and 80% of men aged 35-44, 45-54 and 55-64 years respectively). A further 21%, 16% and 13% were at 'extremely high' risk. Qualitative data revealed that the powerful 'draw' of the football club attracted men otherwise reluctant to attend existing weight management programmes. The location and style of delivery of early FFIT sessions fostered team spirit; men appreciated being with others 'like them' and the opportunity to undertake weight management in circumstances that enhanced physical and symbolic proximity to something they valued highly, the football club. The delivery of a weight management intervention via professional football clubs attracted men at high risk of ill-health. The setting enabled men to join a weight management programme in

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

Science.gov (United States)

Babcock, Dale A.

1995-01-01

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

GM1 erythroimmunoassay for detection and titration of Escherichia coli heat-labile enterotoxin.

OpenAIRE

Germani, Y; Bégaud, E; Guesdon, J L; Moreau, J P

1986-01-01

A GM1 ganglioside erythroimmunoassay for the detection of heat-labile Escherichia coli enterotoxin (LT) was developed for use in poorly equipped laboratories in developing countries. This assay is based on the immunological similarity between Vibrio cholerae toxin and LT and uses cholera toxin antiserum and sheep anti-rabbit immunoglobulin covalently coupled to sheep erythrocytes as conjugate. This assay has the following advantages over other currently available techniques: the reagents it u...

Nasal Delivery of High Molecular Weight Drugs

Directory of Open Access Journals (Sweden)

Erdal Cevher

2009-09-01

Full Text Available Nasal drug delivery may be used for either local or systemic effects. Low molecular weight drugs with are rapidly absorbed through nasal mucosa. The main reasons for this are the high permeability, fairly wide absorption area, porous and thin endothelial basement membrane of the nasal epithelium. Despite the many advantages of the nasal route, limitations such as the high molecular weight (HMW of drugs may impede drug absorption through the nasal mucosa. Recent studies have focused particularly on the nasal application of HMW therapeutic agents such as peptide-protein drugs and vaccines intended for systemic effects. Due to their hydrophilic structure, the nasal bioavailability of peptide and protein drugs is normally less than 1%. Besides their weak mucosal membrane permeability and enzymatic degradation in nasal mucosa, these drugs are rapidly cleared from the nasal cavity after administration because of mucociliary clearance. There are many approaches for increasing the residence time of drug formulations in the nasal cavity resulting in enhanced drug absorption. In this review article, nasal route and transport mechanisms across the nasal mucosa will be briefly presented. In the second part, current studies regarding the nasal application of macromolecular drugs and vaccines with nanoand micro-particulate carrier systems will be summarised.

Steroidogenic activity of high molecular weight forms of ACTH

International Nuclear Information System (INIS)

Gasson, J.C.

1979-01-01

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

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

Science.gov (United States)

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

2013-01-01

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

Computer aided drug discovery of highly ligand efficient, low molecular weight imidazopyridine analogs as FLT3 inhibitors.

Science.gov (United States)

Frett, Brendan; McConnell, Nick; Smith, Catherine C; Wang, Yuanxiang; Shah, Neil P; Li, Hong-yu

2015-04-13

The FLT3 kinase represents an attractive target to effectively treat AML. Unfortunately, no FLT3 targeted therapeutic is currently approved. In line with our continued interests in treating kinase related disease for anti-FLT3 mutant activity, we utilized pioneering synthetic methodology in combination with computer aided drug discovery and identified low molecular weight, highly ligand efficient, FLT3 kinase inhibitors. Compounds were analyzed for biochemical inhibition, their ability to selectively inhibit cell proliferation, for FLT3 mutant activity, and preliminary aqueous solubility. Validated hits were discovered that can serve as starting platforms for lead candidates. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

High molecular weight poly(L-lactide) and poly(ethylene oxide) blends : Thermal characterization and physical properties

NARCIS (Netherlands)

Nijenhuis, AJ; Colstee, E; Grijpma, DW; Pennings, AJ

1996-01-01

The miscibility of high molecular weight poly(L-lactide) (PLLA) with high molecular weight poly(ethylene oxide) (PEG) was studied by differential scanning calorimetry. Ail blends containing up to 50 weight% PEO showed single glass transition temperatures. The PLLA and PEO melting temperatures were

Use of electroporation for high-molecular-weight DNA-mediated gene transfer.

Science.gov (United States)

Jastreboff, M M; Ito, E; Bertino, J R; Narayanan, R

1987-08-01

Electroporation was used to introduce high-molecular-weight DNA into murine hematopoietic cells and NIH3T3 cells. CCRF-CEM cells were stably transfected with SV2NEO plasmid and the genomic DNA from G-418-resistant clones (greater than 65 kb) was introduced into mouse bone marrow and NIH3T3 cells by electroporation. NEO sequences and expression were detected in the hematopoietic tissues of lethally irradiated mice, with 24% of individual spleen colonies expressing NEO. The frequency of genomic DNA transfer into NIH3T3 cells was 0.25 X 10(-3). Electroporation thus offers a powerful mode of gene transfer not only of cloned genes but also of high-molecular-weight DNA into cells.

Relationship between the fluidity of heat-treated coals and molecular weight distributions of their solvent-soluble component; Netsushoritan no yobai kayo seibun no bunshiryo bunpu to ryudosei no kanren

Energy Technology Data Exchange (ETDEWEB)

Yoshida, T.; Takanohashi, T.; Iino, M. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science; Kato, K. [Nippon Steel Co. Ltd., Tokyo (Japan); Fukada, K. [NKK Corp., Tokyo (Japan)

1996-10-28

In order to improve the coke manufacturing process, considerations were given on fluidity manifestation mechanism of heat-treated coals from molecular weight distributions of extracts of a solvent mixed with CS2-N-methyl-2-pyrrolidinone (CS2-NMP). The heat treatment was performed in an autoclave under nitrogen atmosphere at a rate of 3{degree}C/min to settings of 200 to 550{degree}C. The resultant heat-treated coal was quenched, and then extracted by using the CS2-NMP mixed solvent. The fluidity was measured by using a Gieseler plastometer. Maximum extraction rate and the highest fluidity are in linear relationship, which suggests that the extracts govern the fluidity. Since heavy caking coal has no difference in the extraction rates due to heat treatment temperature, and its molecular weight distribution trend does not change, the extracted components which have existed primarily in the original coal govern the fluidity. In semi-caking coals, polymer molecular components are extracted in a large quantity at the softening starting temperature, but the quantity decreases as the temperature rises. However, low-molecular components present no quantitative change, while polymer molecular components decompose, decrease in molecular weight, get solubilized with rising temperature, and act as a binder to cause a flow. 7 figs., 1 tab.

Influence of molecular weight and degree of substitution of various carboxymethyl celluloses on unheated and heated emulsion-type sausage models.

Science.gov (United States)

Gibis, Monika; Schuh, Valerie; Allard, Karin; Weiss, Jochen

2017-03-01

Four carboxymethyl celluloses (CMCs) differing in molecular weight (M W ) and degree of substitution (°DS) were initially characterized in NaCl solution (0.1 M) and on properties of emulsion-type sausage models. The impact of the different CMCs (0-2 wt%) on the rheological behavior and firmness of an emulsion-type sausage models containing 1.8wt% NaCl was studied. Rheology (unheated/heated) and firmness (heated) showed an increasing effect with increasing CMC concentrations. Addition of>1wt% CMC led to a decrease in storage modulus of the unheated/heated batter and to a decrease in firmness of heated independent of the CMC-type used. CLSM revealed that high amounts of CMCs prevented formation of a coherent protein matrix. Water-binding capacity indicated that CMC contributed to the water-retention capability of sausage batters. Small differences between the CMCs were observed using various °DS and similar M W. Results indicate that the addition of low CMC concentrations (≤0.5wt%) may help to reduce fat content. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

Juhas, Mario; Ajioka, James W

2017-05-01

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

Convenient preparation of high molecular weight poly(dimethylsiloxane using thermally latent NHC-catalysis: a structure-activity correlation

Directory of Open Access Journals (Sweden)

Stefan Naumann

2015-11-01

Full Text Available The polymerization of octamethylcyclotetrasiloxane (D4 is investigated using several five-, six- and seven-membered N-heterocyclic carbenes (NHCs. The catalysts are delivered in situ from thermally susceptible CO2 adducts. It is demonstrated that the polymerization can be triggered from a latent state by mild heating, using the highly nucleophilic 1,3,4,5-tetramethylimidazol-2-ylidene as organocatalyst. This way, high molecular weight PDMS is prepared (up to >400 000 g/mol, 1.6 ÐM 95%, using low catalyst loadings (0.2–0.1 mol %. Furthermore, the results suggest that a nucleophilic, zwitterionic mechanism is in operation, in preference to purely anionic polymerization.

The adhesive properties of chlorinated ultra-high molecular weight polyethylene

NARCIS (Netherlands)

Menting, H.N.A.M.; Voets, P.E.L.; Lemstra, P.J.

1995-01-01

Ultra-high molecular weight polyethylene (UHMW-PE) is well known for its abrasion and chemical resistance. Recently we developed a new application for UHMW-PE as a liner in elastomeric hoses. It was found that the adhesion between UHMW-PE and elastomers such as ethylene-propylene-diene monomer

High molecular weight polysaccharide that binds and inhibits virus

Science.gov (United States)

Konowalchuk, Thomas W

2014-01-14

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

High molecular weight polysaccharide that binds and inhibits virus

Energy Technology Data Exchange (ETDEWEB)

Konowalchuk, Thomas W.; Konowalchuk, Jack

2017-07-18

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

Comparative molecular simulation study of low and high density polymer glasses: A competition between attractive and repulsive interactions

Science.gov (United States)

Singh, Jalim; Jose, Prasanth

Results of molecular dynamics simulations of a system of Kremer and Grest linear polymer melts are presented at moderate and high number density. A detailed study of molecular pair distribution function shows that potential of mean force between the molecules has form of Gaussian with an attractive tail at number density ρ = 0.85 (in Lennard-Jones units), which is due to the dominating attractive interactions from temperature T = 0.7. This system shows gelation assisted glass transition, which is interpreted from peaks of molecular structure factor at small wave-numbers. At low temperature, this system phase separate to form dense domains whose local density is high; these domains show many dynamical features of glass transition in monomer and molecular level of relaxation indicating glass transition is assisted by gelation in this system. In the same system, at ρ = 1.0, repulsive interactions dominate, structure does not change even at low temperatures; the system exhibits dynamic heterogeneity and known to undergo glass transition. In this work, we compare and contrast the structure and dynamics of the system near its glass transition. Also, we computed correlation length of systems from the peak value of four-point structural dynamic susceptibility. HPC facility at IIT Mandi.

Application of radiation grafting techniques to prepare the high molecular weight water-soluble polymer

International Nuclear Information System (INIS)

Le Hai; Nguyen Quoc Hien; Nguyen Tan Man; Truong Thi Hanh; Le Huu Tu; Tran Thi Tam; Pham Thi Sam; Pham Anh Tuan; Le Dinh Lang

2003-01-01

The results of the study on the preparation of the high molecular weight water-soluble polymers by radiation grafting and their properties is presented as follows: 1/ by radiation grafting, the molecular weight of PVA was increased 20 times and PAM was increased only 3 times; 2/ the thermal and medium stability of poly(vinyl alcohol) grafted with acrylamide was obviously improved. (LH)

Safety of low-molecular-weight heparin in pregnancy: a systematic review

NARCIS (Netherlands)

Sanson, B. J.; Lensing, A. W.; Prins, M. H.; Ginsberg, J. S.; Barkagan, Z. S.; Lavenne-Pardonge, E.; Brenner, B.; Dulitzky, M.; Nielsen, J. D.; Boda, Z.; Turi, S.; Mac Gillavry, M. R.; Hamulyák, K.; Theunissen, I. M.; Hunt, B. J.; Büller, H. R.

1999-01-01

Unfractionated heparin (UFH) remains the anticoagulant of choice during pregnancy. Low-molecular-weight heparins (LMWH) are an attractive alternative to UFH due to their logistic advantages and their association with a lower incidence of osteoporosis and HIT. We reviewed all published clinical

Trans labilization of am(m)ine ligands from platinum(II) complexes by cancer cell extracts.

Science.gov (United States)

Kasherman, Yonit; Sturup, Stefan; Gibson, Dan

2009-03-01

Cisplatin, cis-[Pt(NH(3))(2)Cl(2)], is an effective anticancer agent in wide clinical use whose efficacy is affected by cellular interactions with sulfur-containing nucleophiles. These interactions can potentially enhance the efficacy of the drug by mediating its delivery to nuclear DNA or inactivate the drug by binding to it irreversibly or by labilizing the NH(3) ligands. Despite the potential importance of trans-labilization reactions in the mechanism of action of the drug, few detailed studies on trans labilization of the ammines have been conducted. We used 2D NMR to show that some trans labilization occurs in proliferating cells and that aqueous extracts of cancer cells labilized 20% of the amine ligands of cis-[PtCl(2)((13)CH(3)NH(2))(2)] after a 12-h incubation. Both low molecular mass nucleophiles (less than 3 kDa) and high molecular mass nucleophiles (more than 3 kDa) labilize the amines with similar efficiency. Studies with model compounds show that thiols and thioethers bind to platinum(II) at similar rates, but thioethers are significantly more efficient at labilizing the am(m)ine at lower pH. N-Acetylcysteine is a more efficient trans-labilizer than glutathione, suggesting that the displacement of the amine proceeds through an associative mechanism. The lag time, the time that elapses from the formation of the Pt-S bond till the release of the amine trans to the sulfur, depends on the pH (for thiols), increasing at lower pH. Quantification of the platinum adducts obtained from incubation of cisplatin with cell extracts indicates that two thirds of the platinum is bound to cellular components with molecular mass greater than 3 kDa.

Investigation of Galactosylated Low Molecular Weight Chitosan ...

African Journals Online (AJOL)

was coupled with low molecular weight chitosan (LMWC) using carbodiimide chemistry. .... High molecular weight chitosan (minimum 85% ..... membrane permeability of drug and mutual repulsion ... coating thickness and the lower solubility of.

Equal channel angular extrusion of ultra-high molecular weight polyethylene

Energy Technology Data Exchange (ETDEWEB)

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

2016-10-01

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

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

Science.gov (United States)

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

2017-08-01

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

Immunogenicity of recombinant Lactobacillus casei-expressing F4 (K88) fimbrial adhesin FaeG in conjunction with a heat-labile enterotoxin A (LTAK63) and heat-labile enterotoxin B (LTB) of enterotoxigenic Escherichia coli as an oral adjuvant in mice.

Science.gov (United States)

Yu, M; Qi, R; Chen, C; Yin, J; Ma, S; Shi, W; Wu, Y; Ge, J; Jiang, Y; Tang, L; Xu, Y; Li, Y

2017-02-01

The aims of this study were to develop an effective oral vaccine against enterotoxigenic Escherichia coli (ETEC) infection and to design new and more versatile mucosal adjuvants. Genetically engineered Lactobacillus casei strains expressing F4 (K88) fimbrial adhesin FaeG (rLpPG-2-FaeG) and either co-expressing heat-labile enterotoxin A (LTA) subunit with an amino acid mutation associated with reduced virulence (LTAK63) and a heat-labile enterotoxin B (LTB) subunit of E. coli (rLpPG-2-LTAK63-co-LTB) or fused-expressing LTAK63 and LTB (rLpPG-2-LTAK63-fu-LTB) were constructed. The immunogenicity of rLpPG-2-FaeG in conjunction with rLpPG-2-LTAK63-co-LTB or rLpPG-2-LTAK63-fu-LTB as an orally administered mucosal adjuvant in mice was evaluated. Results showed that the levels of FaeG-specific serum IgG and mucosal sIgA, as well as the proliferation of lymphocytes, were significantly higher in mice orally co-administered rLpPG-2-FaeG and rLpPG-2-LTAK63-fu-LTB compared with those administered rLpPG-2-FaeG alone, and were lower than those co-administered rLpPG-2-FaeG and rLpPG-2-LTAK63-co-LTB. Moreover, effective protection was observed after challenge with F4+ ETEC strain CVCC 230 in mice co-administered rLpPG-2-FaeG and rLpPG-2-LTAK63-co-LTB or rLpPG-2-FaeG and rLpPG-2-LTAK63-fu-LTB group compared with those that received rLpPG-2-FaeG alone. rLpPG-2-FaeG showed greater immunogenicity in combination with LTAK63 and LTB as molecular adjuvants. Recombinant Lactobacillus provides a promising platform for the development of vaccines against F4+ ETEC infection. © 2016 The Society for Applied Microbiology.

Ultra-Fast RAFT-HDA Click Conjugation: An Efficient Route to High Molecular Weight Block Copolymers.

Science.gov (United States)

Inglis, Andrew J; Stenzel, Martina H; Barner-Kowollik, Christopher

2009-11-02

The use of the reversible addition fragmentation chain transfer-hetero Diels-Alder (RAFT-HDA) click reaction for the modular construction of block copolymers is extended to the generation of high molecular weight materials. Cyclopentadienyl end-functionalized polystyrene (PS-Cp) prepared via both atom transfer radical polymerization (ATRP) and the RAFT process are conjugated to poly(isobornyl acrylate) (PiBoA) (also prepared via RAFT polymerization) to achieve well-defined block copolymers with molecular weights ranging from 34 000 to over 100 000 g · mol(-1) and with small polydispersities (PDI HDA click chemistry can provide access to high molecular weight block copolymers in a simple and straight-forward fashion. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Science.gov (United States)

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

2007-08-01

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

Repair of radiation-induced heat-labile sites is independent of DNA-PKcs, XRCC1 or PARP

Energy Technology Data Exchange (ETDEWEB)

Stenerl& #246; w, Bo; Karlsson, Karin H.; Radulescu, Irina; Rydberg, Bjorn; Stenerlow, Bo

2008-04-29

Ionizing radiation induces a variety of different DNA lesions: in addition to the most critical DNA damage, the DSB, numerous base alterations, SSBs and other modifications of the DNA double-helix are formed. When several non-DSB lesions are clustered within a short distance along DNA, or close to a DSB, they may interfere with the repair of DSBs and affect the measurement of DSB induction and repair. We have previously shown that a substantial fraction of DSBs measured by pulsed-field gel electrophoresis (PFGE) are in fact due to heat-labile sites (HLS) within clustered lesions, thus reflecting an artifact of preparation of genomic DNA at elevated temperature. To further characterize the influence of HLS on DSB induction and repair, four human cell lines (GM5758, GM7166, M059K, U-1810) with apparently normal DSB rejoining were tested for bi-phasic rejoining after gamma irradiation. When heat-released DSBs were excluded from the measurements the fraction of fast rejoining decreased to less than 50% of the total. However, neither the half-times of the fast (t{sub 1/2} = 7-8 min) or slow (t{sub 1/2} = 2.5 h) DSB rejoining were changed significantly. At t=0 the heat-released DSBs accounted for almost 40% of the DSBs, corresponding to 10 extra DSB/cell/Gy in the initial DSB yield. These heat-released DSBs were repaired within 60-90 min in all tested cells, including M059K cells treated with wortmannin or DNA-PKcs defect M059J cells. Furthermore, cells lacking XRCC1 or Poly(ADP-ribose) polymerase-1 (PARP-1) rejoined both total DSBs and heat-released DSBs similar to normal cells. In summary, the presence of heat-labile sites have a substantial impact on DSB induction yields and DSB rejoining rates measured by pulsed-field gel electrophoresis, and HLS repair is independent of DNA-PKcs, XRCC1 and PARP.

Fluids with highly directional attractive forces. III. Multiple attraction sites

International Nuclear Information System (INIS)

Wertheim, M.S.

1986-01-01

The authors derive a reformulation of statistical thermodynamics for fluids of molecules which interact by highly directional attraction. The molecular model consists of a repulsive core and several sites of very short-ranged attraction. The authors explore the relationship between graph cancellation in the fugacity expansion and three types of steric incompatibility between repulsive and attractive interactions involving several molecules. The steric effects are used to best advantage in a limited regrouping of bonds. This controls the density parameters which appear when articulation points are eliminated in the graphical representation. Each density parameter is a singlet density for a species consisting of molecules with a specified set of sites bonded. The densities satisfy subsidiary conditions of internal consistency. These conditions are equivalent to a minimization of the Helmholtz free energy A. Graphical expressions for A and for the pressure are derived. Analogs of the s-particle direct correlation functions and of the Ornstein-Zernike equation are found

Dosimetric features and kinetic analysis of thermoluminescence from ultra-high molecular weight polyethylene

Science.gov (United States)

Chithambo, M. L.

2012-08-01

Thermoluminescence (TL) from beta irradiated ultra-high molecular weight polyethylene has been studied for measurements between 30 and 200 °C. An aliquot studied in this work produced TL glow curves consisting of two peaks, the main peak at 88 °C and a weaker intensity peak at 148 °C for heating at 1 °C s-1 following an excitation dose of 215 Gy. The position of the main peak is poorly reproducible for heating rates of 0.2 and 0.6 °C s-1 investigated with the peak position decreasing when the sample is freshly irradiated and the TL re-measured. The said change in peak position is however less of an effect for measurements made at 1 °C s-1 with the peak position being fairly reproducible in this case. Further measurements of the dosimetric properties of ultra-high molecular weight polyethylene showed that its dose response is linear from 26 Gy to about 161 Gy but exhibits slower growth in intensity with dose from about 860 Gy after regions of sub- and supra-linearity in between. If the TL is not measured immediately after irradiation, the signal fades with the delay approximately exponentially. In addition, a number of tests including phosphorescence analysis showed the possibility that the order of kinetics might not be unique but sensitive to several factors including measurement temperature. Thus for instance, the dependence of the peak position on the stop temperature in the partial heating procedure Tm - Tstop implied first-order kinetics but analysis of the geometrical factor μg for the same set of data gave μg = 0.46 ± 0.03 a value corresponding to characteristics somewhat intermediate between first and second order. In comparison, the results of analysis of the phosphorescence recorded at several temperatures on the rising edge of the main peak were only in agreement for measurements at 40 °C with general-order analysis suggesting second-order kinetics apply as did TL-like transformation of the monotonic phosphorescence decay. Both results were

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

Directory of Open Access Journals (Sweden)

Adler Charles

2009-07-01

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

A covalent attraction between two molecular cation TTF·~+

Institute of Scientific and Technical Information of China (English)

WANG FangFang; WANG Yi; WANG BingQiang; WANG YinFeng; MA Fang; Li ZhiRu

2009-01-01

The optimized structure of the tetrathiafulvalence radical-cation dimer (TTF·~+-TTF·~+) with all-real frequencies is obtained at MP2/6-311G level,which exhibits the attraction between two molecular cation TTF·~+.The new attraction interaction is a 20-center-2-electron intermolecular covalent π/π bonding with a telescope shape.The covalent π/π bonding has the bonding energy of about-21 kcal·mol~(-1) and is concealed by the Coulombic repulsion between two TTF·~+ cations.This intermolecular covalent attraction also influences the structure of the TTF·~+ subunit,I.e.,its molecular plane is bent by an angle θ=5.6°.This work provides new knowledge on intermolecular interaction.

A covalent attraction between two molecular cation TTF·~+

Institute of Scientific and Technical Information of China (English)

无

2009-01-01

The optimized structure of the tetrathiafulvalence radical-cation dimer(TTF·+-TTF·+) with all-real frequencies is obtained at MP2/6-311G level,which exhibits the attraction between two molecular cation TTF·+.The new attraction interaction is a 20-center-2-electron intermolecular covalent π /π bonding with a telescope shape.The covalent π /π bonding has the bonding energy of about -21 kcal·mol-1 and is concealed by the Coulombic repulsion between two TTF·+ cations.This intermolecular covalent attraction also influences the structure of the TTF·+ subunit,i.e.,its molecular plane is bent by an angle θ=5.6°.This work provides new knowledge on intermolecular interaction.

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

Energy Technology Data Exchange (ETDEWEB)

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

2007-08-15

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

Development of gel-filter method for high enrichment of low-molecular weight proteins from serum.

Directory of Open Access Journals (Sweden)

Lingsheng Chen

Full Text Available The human serum proteome has been extensively screened for biomarkers. However, the large dynamic range of protein concentrations in serum and the presence of highly abundant and large molecular weight proteins, make identification and detection changes in the amount of low-molecular weight proteins (LMW, molecular weight ≤ 30kDa difficult. Here, we developed a gel-filter method including four layers of different concentration of tricine SDS-PAGE-based gels to block high-molecular weight proteins and enrich LMW proteins. By utilizing this method, we identified 1,576 proteins (n = 2 from 10 μL serum. Among them, 559 (n = 2 proteins belonged to LMW proteins. Furthermore, this gel-filter method could identify 67.4% and 39.8% more LMW proteins than that in representative methods of glycine SDS-PAGE and optimized-DS, respectively. By utilizing SILAC-AQUA approach with labeled recombinant protein as internal standard, the recovery rate for GST spiked in serum during the treatment of gel-filter, optimized-DS, and ProteoMiner was 33.1 ± 0.01%, 18.7 ± 0.01% and 9.6 ± 0.03%, respectively. These results demonstrate that the gel-filter method offers a rapid, highly reproducible and efficient approach for screening biomarkers from serum through proteomic analyses.

Impact of non-binder ingredients and molecular weight of polymer binders on heat assisted twin screw dry granulation.

Science.gov (United States)

Liu, Y; Thompson, M R; O'Donnell, K P

2018-01-30

Two grades of commercial AFFINISOL™ HPMC HME were used as polymer binders to explore the influence of polymer viscosity and concentration on a novel heat assisted dry granulation process with a twin screw extruder. Contributions of other non-binder ingredients in the formulations were also studied for lactose, microcrystalline cellulose and an active pharmaceutical ingredient of caffeine. As sensitive indicators of processing conditions that expose the drug to high internally generated heat, dehydration of α-lactose monohydrate and polymorphic transformation of caffeine were monitored by differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD). Additionally, any decomposition of caffeine was determined by high-performance liquid chromatography (HPLC). Granular samples were characterized by particle size, circularity, fracture strength and their temperature on the exit of extruder. Higher screw speed and lower feed rate were found to help particles agglomerate by allowing feed particles a greater opportunity to increase in temperature. Lower binder molecular weight and higher binder concentration enable granules to build stronger strength and thereby lead to higher particle size. This new twin screw dry granulation was demonstrated as offering advantages over conventional hot melt granulation by minimizing thermal degradation of the tested ingredients. Copyright © 2017 Elsevier B.V. All rights reserved.

Solvent extraction of cerium (III) with high molecular weight amines

International Nuclear Information System (INIS)

Chatterjee, A.; Basu, S.

1992-01-01

The use of high molecular weight amines in the extraction of cerium (III) as EDTA complex from neutral aqueous medium is reported. The extraction condition was optimised from the study of effects of several variables like concentration of amine and EDTA pH nature of diluents etc. The method has been applied for the determination of cerium in few mineral samples. (author). 7 refs., 5 tabs

Irradiated aromatic polysulphones of increased flow resistance and molecular weight

International Nuclear Information System (INIS)

Staniland, P.A.; Jarrett, W.G.

1976-01-01

Aromatic polymers of increased resistance to flow and molecular weight are obtained by irradiation using β-rays or γ-rays at temperatures up to 400 0 C of an aromatic polymer whose molecular chains comprise benzenoid groups and bivalent linking groups, and where irradiation is γ-rays by heating subsequent to irradiation at 200 to 400 0 C

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

International Nuclear Information System (INIS)

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

2015-01-01

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

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

International Nuclear Information System (INIS)

Folland, R.; Charlesby, A.

1977-01-01

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

Does light attract piglets to the creep area?

Science.gov (United States)

Larsen, M L V; Pedersen, L J

2015-06-01

Hypothermia, experienced by piglets, has been related to piglet deaths and high and early use of a heated creep area is considered important to prevent hypothermia. The aims of the present study were to investigate how a newly invented radiant heat source, eHeat, would affect piglets' use of the creep area and whether light in the creep area works as an attractant on piglets. A total of 39 sows, divided between two batches, were randomly distributed to three heat source treatments: (1) standard infrared heat lamp (CONT, n=19), (2) eHeat with light (EL, n=10) and (3) eHeat without light (ENL, n=10). Recordings of piglets' use of the creep area were made as scan sampling every 10 min for 3 h during two periods, one in daylight (0900 to 1200 h) and one in darkness (2100 to 2400 h), on day 1, 2, 3, 7, 14 and 21 postpartum. On the same days, piglets were weighted. Results showed an interaction between treatment and observation period (Pcreep area during darkness compared with daylight for CONT and EL litters, but not for ENL litters. Piglets average daily weight gain was not affected by treatment, but was positively correlated with piglets' birth weight and was lower in batch 1 compared with batch 2. Seen from the present results, neither eHeat nor light worked as an attractant on piglets; in contrast, piglets preferred to sleep in the dark and it would therefore be recommended to turn off the light in the creep area during darkness. Heating up the creep area without light can be accomplished by using a radiant heat source such as eHeat in contrast to the normally used light-emitting infrared heat lamp.

Aromatic polymers of increased resistance to flow and molecular weight obtained by irradiation

International Nuclear Information System (INIS)

Staniland, P.A.; Jarrett, G.

1976-01-01

Aromatic polymers of increased resistance to flow and increased molecular weight are obtained by irradiation using β rays or gamma rays at temperatures up to 400 0 C of an aromatic polymer whose molecular chains comprise benzenoid groups and bivalent linking groups, and where irradiation is gamma rays by heating subsequent to irradiation at 200 0 C to 400 0 C. The polymeric materials having increased molecular weight are useful for coating non-cooking surfaces of cookware

Removal of high-molecular weight polycyclic aromatic hydrocarbons

Directory of Open Access Journals (Sweden)

Ulrich Vasconcelos

2011-01-01

Full Text Available Alternatives for the removal of high-molecular weight polycyclic aromatic hydrocarbons (HWM-PAH from soil were tested by adding fertilizer or glycerol, as well as the combination of both. Experiments were carried out for 60 days in reactors containing a HWM-PAH-contaminated soil (8030 μg kg-1, accompanied by pH monitoring, humidity control and quantification of total heterotrophic bacteria and total fungus. Fertilizer addition removed 41.6% of HWM-PAH. Fertilizer and glycerol in combination removed 46.2%. When glycerol was added individually, degradation reached 50.4%. Glycerol also promoted the increase of degradation rate during the first 30 days suggesting the HMW-PAH removal occurred through cometabolic pathways.

Freshwater processing of terrestrial dissolved organic matter: What governs lability?

Science.gov (United States)

D'Andrilli, J.; Smith, H. J.; Junker, J. R.; Scholl, E. A.; Foreman, C. M.

2016-12-01

Aquatic and terrestrial ecosystems are linked through the transfer of energy and materials. Allochthonous organic matter (OM) is central to freshwater ecosystem function, influencing local food webs, trophic state, and nutrient availability. In order to understand the nature and fate of OM from inland headwaters to the open ocean, it is imperative to understand the links between OM lability and ecosystem function. Thus, biological, chemical, and physical factors need to be evaluated together to inform our understanding of environmental lability. We performed a laboratory processing experiment on naturally occurring OM leachates from riparian leaves, grasses, and pine needles. Measures of water chemistry, OM optical and molecular characterization, bacterial abundances, microbial assemblage composition, respiration, and C:N:P were integrated to discern the nature and fate of labile and recalcitrant OM in a freshwater stream. Peak processing of all OM sources in the stream water occurred after two days, with spikes in bacterial cell abundances, respiration rates, microbial assemblage shifts, and maximum C utilization. Respiration rates and microbial assemblages were dependent on the degree of lability of the OM molecular composition. Within the first few days, no differences in respiration rates were observed between leachate sources, however, beyond day five, the rates diverged with C processing efficiency correlated with OM lability. Originally comprised of amino acid-like, labile fluorescent species, the inoculated stream water OM became more recalcitrant after 16 days, indicating humification processing over time. Our study highlights the importance of interdisciplinary approaches for understanding the processing and fate of OM in aquatic ecosystems.

High-resolution imaging of labile phosphorus and its relationship with iron redox state in lake sediments

DEFF Research Database (Denmark)

Gao, Yulu; Liang, Tao; Tian, Shuhan

2016-01-01

a regional summer algal bloom. Two-dimensional distributions of labile P in sediments were imaged with the Zr-Oxide DGT without destruction of the original structure of the sediment layer at four sites of the lake. The concentration of DGT-labile P in the sediments, ranging from 0.007 to 0.206 mg L(-1......), was highly heterogeneous across the profiles. The values of apparent diffusion flux (Fd) and release flux (Fr) of P varied between -0.027-0.197 mg m(-2) d(-1) and 0.037-0.332 mg m(-2) d(-1), respectively. Labile P showed a high and positive correlation (p

Modeling of molecular weight and molecular weight distribution in slurry polymerization of propylene by Ziegler-Natta catalysts

International Nuclear Information System (INIS)

Khorasani, R.; Pourmahdian, S.

2007-01-01

The Precise prediction of polypropylene synthesized by heterogeneous Ziegler-Natta catalysts needs good knowledge of parameters affecting on polymerization. molecular weight and molecular weight distribution are among important characteristics of a polymer determining physical-mechanical properties. broadening of molecular weight distribution is an important and well known characteristic of polypropylene synthesized by heterogeneous Ziegler-Natta catalysts, So it is important to understand the origin of broad molecular weight. Two main factors in broadening molecular weight, namely mass transfer resistances and multiplicity of active sites, are discussed in this paper and a model including these factors is presented. Then we calculate molecular weight and molecular weight distribution by the model and compare our results with

Reversible, high molecular weight palladium and platinum coordination polymers based on phosphorus ligands

NARCIS (Netherlands)

Paulusse, J.M.J.; Huijbers, J.P.J.; Sijbesma, R.P.

2005-01-01

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

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

NARCIS (Netherlands)

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

2005-01-01

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

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

Directory of Open Access Journals (Sweden)

Manzoor Ahmad

2012-05-01

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

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

DEFF Research Database (Denmark)

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

2012-01-01

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

Effect of thermal treatment on potato starch evidenced by EPR, XRD and molecular weight distribution.

Science.gov (United States)

Bidzińska, Ewa; Michalec, Marek; Pawcenis, Dominika

2015-12-01

Effect of heating of the potato starch on damages of its structure was investigated by quantitative electron paramagnetic resonance (EPR) spectroscopy, X-ray diffraction and determination of the molecular weight distribution. The measurements were performed in the temperature range commonly used for starch modifications optimizing properties important for industrial applications. Upon thermal treatment, because of breaking of the polymer chains, diminishing of the average molecular weights occurred, which significantly influences generation of radicals, evidenced by EPR. For the relatively mild conditions, with heating parameters not exceeding temperature 230 °C and time of heating equal to 30 min a moderate changes of both the number of thermally generated radicals and the mean molecular weight of the starch were observed. After more drastic thermal treatment (e.g. 2 h at 230 °C), a rapid increase in the radical amount occurred, which was accompanied by significant reduction of the starch molecular size and crystallinity. Experimentally established threshold values of heating parameters should not be exceeded in order to avoid excessive damages of the starch structure accompanied by the formation of the redundant amount of radicals. This requirement is important for industrial applications, because significant destruction of the starch matrix might annihilate the positive influence of the previously performed intentional starch modification. Copyright © 2015 John Wiley & Sons, Ltd.

Conductivity, dielectric behavior and FTIR studies of high molecular weight poly(vinylchloride)-lithium triflate polymer electrolytes

International Nuclear Information System (INIS)

Ramesh, S.; Chai, M.F.

2007-01-01

Thin films of high molecular weight polyvinyl chloride (PVC) with lithium triflate (LiCF 3 SO 3 ) salt were prepared by solution casting method. The ionic conductivity and dielectric measurements were carried out on these films over a wide frequency regime at various temperatures. The conductivity-temperature plots were found to obey classical Arrhenius relationship. The dielectric behavior was analysed using dielectric permittivity and dielectric modulus of the samples. FTIR studies show some simple overlapping and shift in peaks between high molecular weight polyvinyl chloride (PVC) with lithium triflate (LiCF 3 SO 3 ) salt in the polymer electrolyte complexes

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

International Nuclear Information System (INIS)

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

2004-01-01

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

Molecular engineering problems in heat and mass transfer

International Nuclear Information System (INIS)

Kotake, S.

1991-01-01

As for developing, manufacturing and applying new materials of advanced functions such as high-performance devices and high-temperature materials, fundamental understanding of the phenomena from the standpoint of molecular and atomic levels has been required. In these problems, the processes of heat and mass transfer play an important role, being one of the rate-controlling factors. But the energy levels associated with heat and mass transfer are of the orders much less than those of chemical reaction, and it is not easy to understand the thermal problems on the molecular and atomic basis. This paper views the processes of heat and mass transfer from the dynamical motions of atom and molecule for thermal engineering problems. Especially, problems are considered of heat conduction in fine-ceramics, sintered materials of high heat conductivity or high heat-insulation, phase change of condensation in vapor deposition processes such as CVD and PVD, and radiation in laser processing

Conductivity, dielectric behavior and FTIR studies of high molecular weight poly(vinylchloride)-lithium triflate polymer electrolytes

Energy Technology Data Exchange (ETDEWEB)

Ramesh, S. [Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Setapak, 53300 Kuala Lumpur (Malaysia)]. E-mail: ramesh@mail.utar.edu.my; Chai, M.F. [Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Setapak, 53300 Kuala Lumpur (Malaysia)

2007-05-15

Thin films of high molecular weight polyvinyl chloride (PVC) with lithium triflate (LiCF{sub 3}SO{sub 3}) salt were prepared by solution casting method. The ionic conductivity and dielectric measurements were carried out on these films over a wide frequency regime at various temperatures. The conductivity-temperature plots were found to obey classical Arrhenius relationship. The dielectric behavior was analysed using dielectric permittivity and dielectric modulus of the samples. FTIR studies show some simple overlapping and shift in peaks between high molecular weight polyvinyl chloride (PVC) with lithium triflate (LiCF{sub 3}SO{sub 3}) salt in the polymer electrolyte complexes.

Ring-opening polymerization of 19-electron [2]cobaltocenophanes: a route to high-molecular-weight, water-soluble polycobaltocenium polyelectrolytes.

Science.gov (United States)

Mayer, Ulrich F J; Gilroy, Joe B; O'Hare, Dermot; Manners, Ian

2009-08-05

Water-soluble, high-molecular-weight polycobaltocenium polyelectrolytes have been prepared by ring-opening polymerization (ROP) techniques. Anionic polymerization of a strained 19-electron dicarba[2]cobaltocenophane followed by oxidation in the presence of ammonium chloride resulted in the formation of oligomers with up to nine repeat units. Thermal ROP of dicarba[2]cobaltocenophane followed by oxidation in the presence of ammonium nitrate resulted in the formation of high-molecular-weight polycobaltocenium nitrate, a redox-active cobalt-containing polyelectrolyte.

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

Directory of Open Access Journals (Sweden)

Antonella Bisio

2015-03-01

Full Text Available 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

Physical Properties of Low-Molecular Weight Polydimethylsiloxane Fluids

Energy Technology Data Exchange (ETDEWEB)

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

2017-02-01

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

Virus Infection Triggers MAVS Polymers of Distinct Molecular Weight

Directory of Open Access Journals (Sweden)

Natalia Zamorano Cuervo

2018-01-01

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

Analysis of sulfates on low molecular weight heparin using mass spectrometry: structural characterization of enoxaparin.

Science.gov (United States)

Gupta, Rohitesh; Ponnusamy, Moorthy P

2018-05-21

Structural characterization of Low Molecular Weight Heparin (LMWH) is critical to meet biosimilarity standards. In this context, the review focuses on structural analysis of labile sulfates attached to the side-groups of LMWH using mass spectrometry. A comprehensive review of this topic will help readers to identify key strategies for tackling the problem related to sulfate loss. At the same time, various mass spectrometry techniques are presented to facilitate compositional analysis of LMWH, mainly Enoxaparin. Areas covered: This review summarizes findings on mass spectrometry application for LMWH, including modulation of sulfates, using enzymology and sample preparation approaches. Furthermore, popular open-source software packages for automated spectral data interpretation are also discussed. Successful use of LC/MS can decipher structural composition for LMWH and help evaluate their sameness or biosimilarity with the innovator molecule. Overall, the literature has been searched using PubMed by typing various search queries such as "enoxaparin", "mass spectrometry", "low molecular weight heparin", "structural characterization", etc. Expert commentary: This section highlights clinically relevant areas that need improvement to achieve satisfactory commercialization of LMWHs. It also primarily emphasizes the advancements in instrumentation related to mass spectrometry, and discusses building automated software for data interpretation and analysis.

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

Science.gov (United States)

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

2013-01-01

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

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

Czech Academy of Sciences Publication Activity Database

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

2009-01-01

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

Inulin in Medicinal Plants (IV) : Reversed-Phase High-Performance Liquid Chromatography of Inulin after Acetylation : Molecular-Weight Distribution of Inulin in Medicinal Plants

OpenAIRE

三野, 芳紀; 筒井, 聡美; 太田, 長世; YOSHIKI, MINO; SATOMI, TSUTSUI; NAGAYO, OTA; 大阪薬科大学; 大阪薬科大学; 大阪薬科大学; Osaka College of Pharmacy; Osaka College of Pharmacy; Osaka College of Pharmacy

1985-01-01

Reversed-phase high-performance liquid chromatography coupled with pre-acetylation enabled acculate molecular-weight assay of inulin in medicinal plants to be conducted. The results clearly showed that the molecular-weight distribution of inulin varied depending on the stage of growth: Small molecular weight inulin polymers were detected in large quantity in the earlier growth stage whereas large molecular weight inulin polymers at the flowering and post flowering period.

Improving the Application of High Molecular Weight Biotinylated Dextran Amine for Thalamocortical Projection Tracing in the Rat.

Science.gov (United States)

Xu, Dongsheng; Cui, Jingjing; Wang, Jia; Zhang, Zhiyun; She, Chen; Bai, Wanzhu

2018-04-12

High molecular weight biotinylated dextran amine (BDA) has been used as a highly sensitive neuroanatomical tracer for many decades. Since the quality of its labeling was affected by various factors, here, we provide a refined protocol for the application of high molecular weight BDA for studying optimal neural labeling in the central nervous system. After stereotactic injection of BDA into the ventral posteromedial nucleus (VPM) of the thalamus in the rat through a delicate glass pipette, BDA was stained with fluorescent streptavidin-Alexa (AF) 594 and counterstained with fluorescent Nissl stain AF500/525. On the background of green Nissl staining, the red BDA labeling, including neuronal cell bodies and axonal terminals, was more distinctly demonstrated in the somatosensory cortex. Furthermore, double fluorescent staining for BDA and the calcium-binding protein parvalbumin (PV) was carried out to observe the correlation of BDA labeling and PV-positive interneurons in the cortical target, providing the opportunity to study the local neural circuits and their chemical characteristics. Thus, this refined method is not only suitable for visualizing high quality neural labeling with the high molecular weight BDA through reciprocal neural pathways between the thalamus and cerebral cortex, but also will permit the simultaneous demonstration of other neural markers with fluorescent histochemistry or immunochemistry.

Proof of concept for molecular velcro based on the attractive interaction between porphyrin and pyridine containing copolymers

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M. Sievers

2018-06-01

Full Text Available In this short communication, we investigated the synthesis and mixing of porphyrin and pyridine functionalized copolymers as a proof of concept for a velcro-like interaction. A functionalized porphyrin monomer with one polymerizable side chain was synthesized following a rational synthetic pathway. Subsequent copolymerization and careful removal of residual free porphyrin led to poly(n-butyl acrylate-co-5,10,15-triphenyl-20-(3-vinylphenylporphyrin. The immobilized porphyrin was transformed into the corresponding zinc(II complex, which is capable of the coordinative binding of one pyridine moiety. Complete metallation was proven by absorption spectroscopy. 4-Vinylpyridine was immobilized by copolymerization with n-butyl acrylate, too. Via controlled radical polymerization conditions, the molecular weight of poly(n-butyl acrylate-co-4-vinylpyridine was limited to one tenth of the molecular weight of the porphyrin containing copolymer. This large difference in the molecular weight easily allowed identifying the polymers in the mixture of both. With the help of diffusion ordered nuclear magnetic resonance spectroscopy, the complete and temperature-stable precipitation of the porphyrin containing copolymer was observed, proving the expected attractive interaction and supramolecular network formation.

Effects of ionizing radiation on the properties of ultra-high molecular weight polyethylene (PE-UHMW)

International Nuclear Information System (INIS)

Kurth, M.

1990-01-01

Ultra high molecular weight polyethylene (PE-UHMW) is used in most artificial joint replacement devices. Prior to implantation in biological environment, radiatin sterilization by 60 Co or electron beam is common. It is well known that polyethylene exposed to ionizing radiation of any sort undergo physical changes due to chain scission and/or crosslinking. PE-UHMW sheets, 8 mm thick, were either 60 Co or electron beam irradiated, in the range of 10-150 kGy under air or nitrogen atmoshere. The crystallinity of the irradiated samples increases with the irradiation dose. The chain scission/crosslinking events ratio determine the network structure and the sol/gel ratio. The latter was found to depend on irradiation dose, radiation atmosphere and sample thickness. Moreover 60 Co-irradiation is about 5 times more effective in forming PE-UHMW gel than electron-irradiation. Besides the degree of crosslinking, the molecular weight distribution is the main determinant of the structural properties of PE-UHMW. Low molecular weight fractions were also found. Using a dose of 30 kGy ( 60 Co in air), the average molecular weight of the soluble part after extraction decreased from originally 2.3 million g/mol to 170.000 g/mol, corresponding to a factor of about 10. These changes in molecular weight have a strong influence on the mechanical properties of PE-UHMW. Crosslinking slightly increases the yield strength, while the elongation at break decreases. Long-term compressive creep is reduced if the material is irradiated. Obviously, increased crystallinity after oxidative chain scission affects a higher deformation resistance. Radiation crosslinked structures cause a significant increase in abrasion resistance. The above described structural changes occur even upon irradiation of very low doses as used during sterilization. This study will enable to reduce the radiation sterilization damage and thus to gain long term stability of PE-UHMW medical devices. (orig./BBR)

Adolescent Perceptions of Body Weight and Attractiveness: Important Issues in Alcohol and Illicit Drug Use?

Science.gov (United States)

Page, Randy M.; And Others

1995-01-01

Examined relationship between adolescent self-perception of body weight and physical attractiveness and the use of alcohol and drugs in high school students (n=1,915). In general, adolescents dissatisfied with their appearance used illicit substances and got drunk more often than those satisfied with their appearance. (SNR)

Effect of the molecular weight of a neutral polysaccharide on soy protein gelation.

Science.gov (United States)

Monteiro, Sónia R; Lopes-da-Silva, José A

2017-12-01

The effects of galactomannans with different molecular weights on the heat-induced gelation characteristics of soybean protein were investigated using dynamic small-strain rheometry, under conditions where the proteins carry a net negative charge (pH7). Microstructure of the resulting gels was investigated by confocal laser scanning microscopy. Phase-separated systems were obtained with different morphologies and degree of phase separation, depending on both biopolymer concentrations and polysaccharide molecular weight. In general, a gelling enhancing effect on soy proteins was verified, despite extensive phase-separation processes observed at the higher polysaccharide molecular weight. This effect was demonstrated by an increase of the gelation rate, a decrease in the temperature at the onset of gelation, and an increase of gel stiffness and elastic character, with the length of polysaccharide chains. Overall, the results obtained established that the judicious selection of the galactomannan molecular weight may be used to modify the structure and gelation properties of soy proteins, originating a diversity of rheological characteristics and microstructures that will impact on the design of novel food formulations. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

Rivera, Fabrizio

2016-03-01

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

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

Science.gov (United States)

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

2013-06-01

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

Functional Comparison for Lipid Metabolism and Intestinal and Fecal Microflora Enzyme Activities between Low Molecular Weight Chitosan and Chitosan Oligosaccharide in High-Fat-Diet-Fed Rats.

Science.gov (United States)

Chiu, Chen-Yuan; Feng, Shih-An; Liu, Shing-Hwa; Chiang, Meng-Tsan

2017-07-24

The present study investigated and compared the regulatory effects on the lipid-related metabolism and intestinal disaccharidase/fecal bacterial enzyme activities between low molecular weight chitosan and chitosan oligosaccharide in high-fat-diet-fed rats. Diet supplementation of low molecular weight chitosan showed greater efficiency than chitosan oligosaccharide in suppressing the increased weights in body and in liver and adipose tissues of high-fat-diet-fed rats. Supplementation of low molecular weight chitosan also showed a greater improvement than chitosan oligosaccharide in imbalance of plasma, hepatic, and fecal lipid profiles, and intestinal disaccharidase activities in high-fat-diet-fed rats. Moreover, both low molecular weight chitosan and chitosan oligosaccharide significantly decreased the fecal microflora mucinase and β-glucuronidase activities in high-fat-diet-fed rats. These results suggest that low molecular weight chitosan exerts a greater positive improvement than chitosan oligosaccharide in lipid metabolism and intestinal disaccharidase activity in high-fat-diet-induced obese rats.

Fluids with highly directional attractive forces. IV. Equilibrium polymerization

International Nuclear Information System (INIS)

Wertheim, M.S.

1986-01-01

The author investigates approximation methods for systems of molecules interacting by core repulsion and highly directional attraction due to several attraction sites. The force model chosen imitates a chemical bond by providing for bond saturation when binding occurs. The dense fluid is an equilibrium mixture of s-mers with mutual repulsion. The author uses a previously derived reformulation of statistical thermodynamics in which the particle species are monomeric units with a specified set of attraction sites bonded. Thermodynamic perturbation theory (TPT) and integral equations of two types are derived. The use of TPT is illustrated by explicit calculation for a molecular model with two attraction sites capable of forming chain and ring polymers. Successes and defects of TPT are discussed. The integral equations for pair correlations between particles of specified bonding include calculation of self-consistent densities of species. Methods of calculating thermodynamic properties from the solutions of integral equations are given

Effect of molecular weight distribution on e-beam exposure properties of polystyrene

International Nuclear Information System (INIS)

Dey, Ripon Kumar; Cui Bo

2013-01-01

Polystyrene is a negative electron beam resist whose exposure properties can be tuned simply by using different molecular weights (Mw). Most previous studies have used monodisperse polystyrene with a polydispersity index (PDI) of less than 1.1 in order to avoid any uncertainties. Here we show that despite the fact that polystyrene’s sensitivity is inversely proportional to its Mw, no noticeable effect of very broad molecular weight distribution on sensitivity, contrast and achievable resolution is observed. It is thus unnecessary to use the costly monodisperse polystyrene for electron beam lithography. Since the polydispersity is unknown for general purpose polystyrene, we simulated a high PDI polystyrene by mixing in a 1:1 weight ratio two polystyrene samples with Mw of 170 and 900 kg mol −1 for the high Mw range, and 2.5 and 13 kg mol −1 for the low Mw range. The exposure property of the mixture resembles that of a monodisperse polystyrene with similar number averaged molecular weight (Mn)-bar, which indicates that it is (Mn)-bar rather than (Mw)-bar (weight averaged molecular weight) that dominates the exposure properties of polystyrene resist. This also implies that polystyrene of a certain molecular weight can be simulated by a mixture of two polystyrenes having different molecular weights. (paper)

Does light attract piglets to the creep area?

DEFF Research Database (Denmark)

Larsen, Mona Lilian Vestbjerg; Pedersen, Lene Juul

2015-01-01

Hypothermia, experienced by piglets, has been related to piglet deaths and high and early use of a heated creep area is considered important to prevent hypothermia. The aims of the present study were to investigate how a newly invented radiant heat source, eHeat, would affect piglets' use...... of the creep area and whether light in the creep area works as an attractant on piglets. A total of 39 sows, divided between two batches, were randomly distributed to three heat source treatments: (1) standard infrared heat lamp (CONT, n=19), (2) eHeat with light (EL, n=10) and (3) eHeat without light (ENL, n......=10). Recordings of piglets' use of the creep area were made as scan sampling every 10 min for 3 h during two periods, one in daylight (0900 to 1200 h) and one in darkness (2100 to 2400 h), on day 1, 2, 3, 7, 14 and 21 postpartum. On the same days, piglets were weighted. Results showed an interaction...

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

OpenAIRE

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

2016-01-01

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

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

DEFF Research Database (Denmark)

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

2018-01-01

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

Body Weight and Matching with a Physically Attractive Romantic Partner

Science.gov (United States)

Carmalt, Julie H.; Cawley, John; Joyner, Kara; Sobal, Jeffery

2008-01-01

Matching and attribute trade are two perspectives used to explain mate selection. We investigated patterns of matching and trade, focusing on obesity, using Add Health Romantic Pair data (N = 1,405 couples). Obese individuals, relative to healthy weight individuals, were less likely to have physically attractive partners, with this disadvantage…

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

Science.gov (United States)

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

2011-12-01

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

Thermal parameter identification for non-Fourier heat transfer from molecular dynamics

Science.gov (United States)

Singh, Amit; Tadmor, Ellad B.

2015-10-01

Fourier's law leads to a diffusive model of heat transfer in which a thermal signal propagates infinitely fast and the only material parameter is the thermal conductivity. In micro- and nano-scale systems, non-Fourier effects involving coupled diffusion and wavelike propagation of heat can become important. An extension of Fourier's law to account for such effects leads to a Jeffreys-type model for heat transfer with two relaxation times. We propose a new Thermal Parameter Identification (TPI) method for obtaining the Jeffreys-type thermal parameters from molecular dynamics simulations. The TPI method makes use of a nonlinear regression-based approach for obtaining the coefficients in analytical expressions for cosine and sine-weighted averages of temperature and heat flux over the length of the system. The method is applied to argon nanobeams over a range of temperature and system sizes. The results for thermal conductivity are found to be in good agreement with standard Green-Kubo and direct method calculations. The TPI method is more efficient for systems with high diffusivity and has the advantage, that unlike the direct method, it is free from the influence of thermostats. In addition, the method provides the thermal relaxation times for argon. Using the determined parameters, the Jeffreys-type model is able to reproduce the molecular dynamics results for a short-duration heat pulse where wavelike propagation of heat is observed thereby confirming the existence of second sound in argon. An implementation of the TPI method in MATLAB is available as part of the online supplementary material.

Degradation and mineralization of high-molecular-weight polycyclic aromatic hydrocarbons by defined fungal-bacterial cocultures

International Nuclear Information System (INIS)

Boonchan, S.; Britz, M.L.; Stanley, G.A.

2000-01-01

This study investigated the biodegradation of high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) in liquid media and soil by bacteria (Stenotrophomonas maltophilia VUN 10,010 and bacterial consortium VUN 10,009) and a fungus (Penicillium janthinellum VUO 10,201) that were isolated from separate creosote- and manufactured-gas plant-contaminated soils. The bacteria could use pyrene as their sole carbon and energy source in a basal salts medium (BSM) and mineralized significant amounts of benzo[a]pyrene cometabolically when pyrene was also present in BSM. P. janthinellum VUO 10,201 could not utilize any high-molecular-weight PAH as sole carbon and energy source but could partially degrade these if cultured in a nutrient broth. Although small amounts of chrysene, benz[a]pyrene, and dibenz[a,h]anthracene were degraded by axenic cultures of these isolates in BSM containing a single PAH, such conditions did not support significant microbial growth or PAH mineralization. However, significant degradation of, and microbial growth on, pyrene, chrysene, benz[a]anthracene, benzo[a]pyrene, and dibenz[a,h]anthracene, each as a single PAH in BSM, occurred when P. janthinellum VUO 10,201 and either bacterial consortium VUN 10,009 or S. maltophilia VUN 10,010 were combined in the one culture, i.e., fungal-bacterial cocultures: 25% of the benzo[a]pyrene was mineralized to CO 2 by these cocultures over 49 days, accompanied by transient accumulation and disappearance of intermediates detected by high-pressure liquid chromatography. Inoculation of fungal-bacterial cocultures into PAH-contaminated soil resulted in significantly improved degradation of high-molecular-weight PAHs, benzo[a]pyrene mineralization, and reduction in the mutagenicity of organic soil extracts, compared with the indigenous microbes and soil amended with only axenic inocula

Role of Molecular Weight Distribution on Charge Transport in Semiconducting Polymers

KAUST Repository

Himmelberger, Scott

2014-10-28

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

Determination of low molecular weight thiols using monobromobimane fluorescent labeling and high-performance liquid chromatography

Science.gov (United States)

Fahey, Robert C.; Newton, Gerald L.

1988-01-01

Methods are described for the preparation and high-performance liquid chromatography (HPLC) analysis of monobromobimane derivatives of low molecular weight thiols in extracts of biological samples. Typical problems encountered in the development and application of these methods are discussed. Analysis of mung bean extract is used as an example.

Synthesis and properties of ionic polyurethane dispersions: influence of polyol molecular weight

International Nuclear Information System (INIS)

Valipour Ebrahimi, M.; Barikani, M.; Mohammad Seyed Mohaghegh, S.

2006-01-01

A series of water dispersible polyurethanes containing carboxylate anion as the hydrophilic pendant group were prepared from toluene diisocyanate (TDI), 1,4- butanediol (1,4-BDO), dimethylol propionic acid and different molecular weight of polytetramethylene glycol . IR Spectroscopy was used to check the end of polymerization reaction and characterization of polymer. The effect of polytetramethylene glycol molecular weight was studied on the particle size distribution, contact angle, and mechanical and thermal properties of the emulsion-cast films. Average particle size of prepared polyurethane emulsions decreases with increasing the polytetramethylene glycol molecular weight. Tensile strength and hardness decrease and elongation-at-break and contact angle increase with increase of the polytetramethylene glycol molecular weight. Thermal property and thermal stability are also effected by variation of polytetramethylene glycol molecular weight. The thermal stability increases with increasing polytetramethylene glycol molecular weight. Glass transition temperature (T g ) moved toward the lower temperatures by increasing molecular weight of the polyol. Decrease in T g and tensile properties are interpreted in terms of the decrease in hard segments and the increase in chain flexibility and phase separation in high molecular weight polytetramethylene glycol based polyurethane

Molecular-scale hydrophobic interactions between hard-sphere reference solutes are attractive and endothermic.

Science.gov (United States)

Chaudhari, Mangesh I; Holleran, Sinead A; Ashbaugh, Henry S; Pratt, Lawrence R

2013-12-17

The osmotic second virial coefficients, B2, for atomic-sized hard spheres in water are attractive (B2 attractive with increasing temperature (ΔB2/ΔT attractive and endothermic at moderate temperatures. Hydrophobic interactions between atomic-sized hard spheres in water are more attractive than predicted by the available statistical mechanical theory. These results constitute an initial step toward detailed molecular theory of additional intermolecular interaction features, specifically, attractive interactions associated with hydrophobic solutes.

Acid-Labile Amphiphilic PEO-b-PPO-b-PEO Copolymers: Degradable Poloxamer Analogs.

Science.gov (United States)

Worm, Matthias; Kang, Biao; Dingels, Carsten; Wurm, Frederik R; Frey, Holger

2016-05-01

Poly ((ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)) triblock copolymers commonly known as poloxamers or Pluronics constitute an important class of nonionic, biocompatible surfactants. Here, a method is reported to incorporate two acid-labile acetal moieties in the backbone of poloxamers to generate acid-cleavable nonionic surfactants. Poly(propylene oxide) is functionalized by means of an acetate-protected vinyl ether to introduce acetal units. Three cleavable PEO-PPO-PEO triblock copolymers (Mn,total = 6600, 8000, 9150 g·mol(-1) ; Mn,PEO = 2200, 3600, 4750 g·mol(-1) ) have been synthesized using anionic ring-opening polymerization. The amphiphilic copolymers exhibit narrow molecular weight distributions (Ð = 1.06-1.08). Surface tension measurements reveal surface-active behavior in aqueous solution comparable to established noncleavable poloxamers. Complete hydrolysis of the labile junctions after acidic treatment is verified by size exclusion chromatography. The block copolymers have been employed as surfactants in a miniemulsion polymerization to generate polystyrene (PS) nanoparticles with mean diameters of ≈200 nm and narrow size distribution, as determined by dynamic light scattering and scanning electron microscopy. Acid-triggered precipitation facilitates removal of surfactant fragments from the nanoparticles, which simplifies purification and enables nanoparticle precipitation "on demand." © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Topochemical approach to efficiently produce main-chain poly(bile acid)s with high molecular weights.

Science.gov (United States)

Li, Weina; Li, Xuesong; Zhu, Wei; Li, Changxu; Xu, Dan; Ju, Yong; Li, Guangtao

2011-07-21

Based on a topochemical approach, a strategy for efficiently producing main-chain poly(bile acid)s in the solid state was developed. This strategy allows for facile and scalable synthesis of main-chain poly(bile acid)s not only with high molecular weights, but also with quantitative conversions and yields.

High molecular weight hyaluronic acid increases the differentiation potential of the murine chondrocytic ATDC5 cell line.

Science.gov (United States)

Sato, Eiichi; Ando, Takashi; Ichikawa, Jiro; Okita, Genki; Sato, Nobutaka; Wako, Masanori; Ohba, Tetsuro; Ochiai, Satoshi; Hagino, Tetsuo; Jacobson, Richard; Haro, Hirotaka

2014-12-01

Osteoarthritis (OA) is a group of common, chronic, and painful inflammatory joint diseases. One important finding in OA patients is a remarkable decrease in the molecular weight of hyaluronic acid (HA) in the synovial fluid of affected joints. Therapeutic HA is available to patients in most parts of the world as a viscosupplementation product for the treatment of OA. Previous clinical reports show that high molecular weight HA (HMWHA) more effectively relieves pain than low molecular weight HA (LMWHA). However, the mechanism behind this finding remains unclear. In this study, we investigated whether a LMWHA (Low-0.9 MDa) and two types of HMWHA (High-1.9 MDa and 6 MDa) differentially affected chondroregulatory action. We tested this using ATDC5 cell, a murine chondrocytic cell line widely used in culture systems to study chondrogenic differentiation. We found that HMWHA, especially hylan G-F 20 (High-6 MDa), significantly induced aggrecan and proteoglycan accumulation, nodule formation, and mRNA expression of chondrogenic differentiation markers in a time- and dose-dependent manner. In addition, we showed that HMWHA prevented TNF-α induced inhibition of chondrogenic differentiation, with no effect on cell proliferation or viability. These results reveal that HMWHA significantly promotes chondrogenic differentiation of ATDC5 cells in vitro, and suggest that HMWHA plays a significant chondroregulatory role in vivo. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Effects of low molecular weight organic acids on 137Cs release from contaminated soils

International Nuclear Information System (INIS)

Chiang, Po Neng; Wang, Ming Kuang; Huang, Pan Ming; Wang, Jeng Jong

2011-01-01

Radio pollutant removal is one of several priority restoration strategies for the environment. This study assessed the effect of low molecular weight organic acid on the lability and mechanisms for release of 137 Cs from contaminated soils. The amount of 137 Cs radioactivity released from contaminated soils reacting with 0.02 M low molecular weight organic acids (LMWOAs) specifically acetic, succinic, oxalic, tartaric, and citric acid over 48 h were 265, 370, 760, 850, and 1002 Bq kg -1 , respectively. The kinetic results indicate that 137 Cs exhibits a two-step parabolic diffusion equation and a good linear relationship, indicating that the parabolic diffusion equation describes the data quite well, as shown by low p and high r 2 values. The fast stage, which was found to occur within a short period of time (0.083-3 h), corresponds to the interaction of LMWOAs with the surface of clay minerals; meanwhile, during the slow stage, which occurs over a much longer time period (3-24 h), desorption primarily is attributed to inter-particle or intra-particle diffusion. After a fifth renewal of the LMWOAs, the total levels of 137 Cs radioactivity released by acetic, succinic, oxalic, tartaric, and citric acid were equivalent to 390, 520, 3949, 2061, and 4422 Bq kg -1 soil, respectively. H + can protonate the hydroxyl groups and oxygen atoms at the broken edges or surfaces of the minerals, thereby weakening Fe-O and Al-O bonds. After protonation of H + , organic ligands can attack the OH and OH 2 groups in the minerals easily, to form complexes with surface structure cations, such as Al and Fe. The amounts of 137 Cs released from contaminated soil treated with LMWOAs were substantially increased, indicating that the LMWOAs excreted by the roots of plants play a critical role in 137 Cs release.

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

NARCIS (Netherlands)

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

2008-01-01

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

Low molecular weight salts combined with fluorinated solvents for electrolytes

Science.gov (United States)

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

2015-11-10

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

Labile and Non-labile Soil Carbon Fractions Equally Contributed to Carbon Changes under Long-term Fertilization

Science.gov (United States)

Liang, F.; Li, J.; Xu, M.; Huang, S.

2017-12-01

Soil organic carbon (SOC) storages are altered under long-term fertilization in croplands, it however remains unclear how fast- to slow-cycling SOC fractions each respond to fertilization practices. Based on five two-decade Chinese long-term fertilization experiments (GZL: Gongzhuling; ZZ: Zhengzhou; CQ: Chongqing; JX: Jinxian; QY: Qiyang) under three fertilization treatments (CK: cropping with no fertilizer input; NPK: chemical nitrogen, phosphorus and potassium fertilizers; and NPKM: NPK with manure input), we quantified very labile, labile, non-labile and total SOC stocks at 0-20cm soil depth. Results showed that SOC stocks varied among sites (GZL, JX, CQ > ZZ, QY) and generally increased with fertilizations (CK-1 at ZZ, GZL, QY, CQ and JX, respectively. The corresponding changes of the sum of very labile and labile SOC fractions were 2.6, 2.0, 1.8, 0.8 and -0.5 Mg ha-1 at ZZ, QY, GZL, CQ and JX, respectively. Also, NPKM increased total SOC stock by 18.3, 16.2, 14.4, 10.5, and 6.5 Mg ha-1 at QY, GZL, ZZ, CQ and JX, respectively. The corresponding changes of the sum of very labile and labile SOC fractions were 8.6, 6.8, 6.6, 3.2 and -1.6 Mg ha-1 at QY, GZL, ZZ, CQ and JX, respectively. These results suggested that about half or more than half SOC stock accretions under fertilization were induced by increase in non-labile SOC fractions. It thus informs the importance of non-labile SOC fractions in contributing to soil C sequestration under long-term fertilizations in Chinese croplands. Future research should improve our mechanistic understanding of biogeochemical transformation of non-labile organic C in soils.

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

CERN Document Server

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

2002-01-01

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

Structural modifications of ultra-high molecular weight polyethylene (UHMWPE) processed in attritor type mill

International Nuclear Information System (INIS)

Gabriel, Melina C.; Carvalho, Benjamim de M.; Pinheiro, Luis A.; Cintho, Osvaldo M.; Capocchi, Jose D.T.; Kubaski, Evaldo T.

2009-01-01

Ultra-high molecular weight polyethylene (UHMWPE) is a polyethylene that has a high melt viscosity, hence its processing becomes very difficult. High-energy mechanical milling provides physical and chemical changes in polymers that have been studied recently. In order to study these changes in UHMWPE, powder of this polymer was mechanical milled in attritor type mill with a ball-to-powder weight ratio of 40:1 for 8 hours, varying the rotation speed: 200, 300, 400, 500 e 600 rpm. The polymer was characterized by scanning electron microscopy (SEM) and xray diffraction (XRD). From the XRD results it was noted that as the rotation speed increased the monoclinic phase also increased up to 500 rpm. For 600 rpm, the amount of monoclinic phase apparently decreased. At this rotation speed, the deformation rate probably increased the process temperature, allowing the monoclinic phase to return to its initial structural orthorhombic form. (author)

Effect of electron beam radiation on the structure and mechanical properties of ultra high molecular weight polyethylene fibers

International Nuclear Information System (INIS)

Li Shujun; Sun Weijun; Liu Xiuju; Gao Yongzhong; Li Huisheng

1998-01-01

Ultra high molecular weight polyethylene fibers have been crosslinked by electron beam. The structure and mechanical properties of them have been investigated in different irradiation atmospheres. The obtained results show that the gel content and crosslinking density increase with the increase of dose, the swelling ratio and average molecular weight of crosslinked net decrease with the increase of dose, the tensile strength and failure elongation decrease with the increase of dose, the tensile modulus increases with the increase of dose. When the samples are irradiated in air, vacuum and acetylene atmospheres, the effect of irradiation in acetylene atmosphere is best

Free radicals. High-resolution spectroscopy and molecular structure

International Nuclear Information System (INIS)

Hirota, E.

1983-01-01

High-resolution, high-sensitivity spectroscopy using CW laser and microwave sources has been applied to free radicals and transient molecules to establish their existence and to explore their properties in detail. The radicals studied were mainly generated by discharge-induced reactions. A few molecules are used as typical examples to illustrate the results so far obtained. The molecular and electronic structures of free radicals, intramolecular motions of large amplitudes in some labile molecules, and metastable electronic states of carbenes are given special emphasis. The significance of the present spectroscopic results in other related fields such as astronomy and atmospheric chemistry is stressed. 4 figures, 3 tables

Analysis of co-eluted isomers of high-molecular weight polycyclic aromatic hydrocarbons in high performance liquid chromatography fractions via solid-phase nanoextraction and time-resolved Shpol'skii spectroscopy.

Science.gov (United States)

Wilson, Walter B; Campiglia, Andres D

2011-09-28

We present an accurate method for the determination of isomers of high-molecular weight polycyclic aromatic hydrocarbons co-eluted in HPLC fractions. The feasibility of this approach is demonstrated with two isomers of molecular weight 302 with identical mass fragmentation patterns, namely dibenzo[a,i]pyrene and naphtho[2,3-a]pyrene. Qualitative and quantitative analysis is carried out via laser-excited time-resolved Shpol'skii spectroscopy at liquid helium temperature. Unambiguous identification of co-eluted isomers is based on their characteristic 4.2 K line-narrowed spectra in n-octane as well as their fluorescence lifetimes. Pre-concentration of HPLC fractions prior to spectroscopic analysis is performed with the aid of gold nanoparticles via an environmentally friendly procedure. In addition to the two co-eluted isomers, the analytical figures of merit of the entire procedure were evaluated with dibenzo[a,l]pyrene, dibenzo[a,h]pyrene and dibenzo[a,e]pyrene. The analytical recoveries from drinking water samples varied between 98.2±5.5 (dibenzo[a,l]pyrene) and 102.7±3.2% (dibenzo[a,i]pyrene). The limits of detection ranged from 51.1 ng L(-1) (naphtho[2,3-a]pyrene) to 154 ng L(-1) (dibenzo[a,e]pyrene). The excellent analytical figures of merit associated to its HPLC compatibility makes this approach an attractive alternative for the analysis of co-eluted isomers with identical mass spectra. Copyright © 2011 Elsevier B.V. All rights reserved.

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

Science.gov (United States)

Schwessinger, Benjamin; Rathjen, John P

2017-01-01

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

Molecular weight distribution of Athabasca bitumen

Energy Technology Data Exchange (ETDEWEB)

Champagne, P J; Manolakis, E; Ternan, M

1985-03-01

A sample of whole Athabasca bitumen has been fractionated by preparative g.p.c. The weights of the fractions have been determined and their molecular weights measured by several methods. In contras to previously published data, consistent results were obtained using different solvents (THF, benzene/water) and using different techniques (v.p.o., f.p.d. and g.c.-m.s.). This has resulted in a accurate definition of the molecular weight distribution of Athabasca bitumen.

Thermal transport in semicrystalline polyethylene by molecular dynamics simulation

Science.gov (United States)

Lu, Tingyu; Kim, Kyunghoon; Li, Xiaobo; Zhou, Jun; Chen, Gang; Liu, Jun

2018-01-01

Recent research has highlighted the potential to achieve high-thermal-conductivity polymers by aligning their molecular chains. Combined with other merits, such as low-cost, corrosion resistance, and light weight, such polymers are attractive for heat transfer applications. Due to their quasi-one-dimensional structural nature, the understanding on the thermal transport in those ultra-drawn semicrystalline polymer fibers or films is still lacking. In this paper, we built the ideal repeating units of semicrystalline polyethylene and studied their dependence of thermal conductivity on different crystallinity and interlamellar topology using the molecular dynamics simulations. We found that the conventional models, such as the Choy-Young's model, the series model, and Takayanagi's model, cannot accurately predict the thermal conductivity of the quasi-one-dimensional semicrystalline polyethylene. A modified Takayanagi's model was proposed to explain the dependence of thermal conductivity on the bridge number at intermediate and high crystallinity. We also analyzed the heat transfer pathways and demonstrated the substantial role of interlamellar bridges in the thermal transport in the semicrystalline polyethylene. Our work could contribute to the understanding of the structure-property relationship in semicrystalline polymers and shed some light on the development of plastic heat sinks and thermal management in flexible electronics.

Characterization of high molecular weight cadmium species in contaminated vegetable food

Energy Technology Data Exchange (ETDEWEB)

Guenther, K.; Kastenholz, B. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Chemie und Dynamik der Geosphaere 7: Angewandte Physikalische Chemie; Ji, G. [Bonn Univ. (Germany). Lehrstuhl fuer Lebensmittelwissenschaft und Lebensmittelchemie

2000-10-01

Spinach and radish grown from seeds were each contaminated with 4 different amounts of cadmium. After a cell breakdown of the eatable parts and centrifugation of the resulting homogenates all supernatants (cytosols) were separated by gel permeation chromatography (GPC). The size-range of the GPC method used was about 20-8000 kDa for globular proteins. The high molecular weight (HMW-Cd-SP, 150-700 kDa) and the low molecular weight Cd species (LMW-Cd-SP, < 150 kDa) in all plant cytosols eluted at about the same retention volume by GPC. The most important Cd binding form in the cytosols of all plants was found to be HMW-Cd-SP. The Cd elution maxima were detected in the range of about 200 kDa. The Cd determinations were performed with ET-AAS by means of matrix modifier. By incubating chosen cytosols with a proteinase before the GPC it was verified that the HMW-Cd-SP in both vegetables are Cd proteins. The molar proportions protein/Cd were about 2-6 in the respective GPC fractions of the HMW-Cd-SP of the highest contaminated plants. The GPC fractions of the HMW-Cd-SP of spinach and radish were further separated by a preparative, native and continuous polyacrylamide gel electrophoresis (PAGE) method. At pH 8 the species were negatively charged, had only a small UV-absorption at 280 nm and showed a very similar elution behavior in all analyzed cytosols. Therefore, we suppose that the HMW-Cd-SP of these two different vegetable foodstuffs have a very similar chemical structure. (orig.)

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

Science.gov (United States)

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

2016-12-01

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

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

Lifescience Database Archive (English)

Full Text Available List Contact us NBDC NikkajiRDF Molecular Formula and Molecular Weight Data detail Data name Molecular Formula and Molecul...- Description of data contents This RDF data includes molecular formula and molecular weight of chemical sub...ikkajiRDF_MFMW.tar.gz File size: 404 MB Simple search URL - Data acquisition method The data was converted from data of molecul...ar formulas and molecular weights in Basic Information ( http://dbarchive.biosciencedbc.j... Policy | Contact Us Molecular Formula and Molecular Weight - NBDC NikkajiRDF | LSDB Archive ...

Studies on a microbially derived, high molecular weight inhibitor of plasma cholesteryl ester transfer protein

International Nuclear Information System (INIS)

Marschke, C.K.; McGee, J.E.; Melchior, G.W.; Castle, C.K.

1989-01-01

The authors have isolated an organism which accumulates an inhibitor of Cholesteryl Ester Transfer Protein (CETP). Purification of 100,000-fold was achieved by ammonium sulfate precipitation followed by Hydroxyl Apatite, Agarose AO.5, and Mono Q (Pharmacia) chromatographies. The use of 14 C-labelled protein molecular weight standards followed by SDS-PAGE revealed some proteolytic activity. However, inhibition of the proteases did not affect the inhibitor potency. The inhibitor has an estimated molecular weight of 40 Kd and appears to exist as two forms. One form was eluted from a Mono Q column by 100 mM NaCl while the other was not bound. Our evidence indicated that the bound form was progressively denatured, or proteolyzed, during storage of the fermentation beer, to the unbound form. Importantly though this molecular change did not affect either inhibitory activity or the apparent molecular weight

PHOTOCHEMICAL HEATING OF DENSE MOLECULAR GAS

Energy Technology Data Exchange (ETDEWEB)

Glassgold, A. E. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Najita, J. R. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)

2015-09-10

Photochemical heating is analyzed with an emphasis on the heating generated by chemical reactions initiated by the products of photodissociation and photoionization. The immediate products are slowed down by collisions with the ambient gas and then heat the gas. In addition to this direct process, heating is also produced by the subsequent chemical reactions initiated by these products. Some of this chemical heating comes from the kinetic energy of the reaction products and the rest from collisional de-excitation of the product atoms and molecules. In considering dense gas dominated by molecular hydrogen, we find that the chemical heating is sometimes as large, if not much larger than, the direct heating. In very dense gas, the total photochemical heating approaches 10 eV per photodissociation (or photoionization), competitive with other ways of heating molecular gas.

Flexible mechanoprosthesis made from woven ultra-high-molecular-weight polyethylene fibres : proof of concept in a chronic sheep model

NARCIS (Netherlands)

Basir, Amir; Grobben, Remco B.; Cramer, Maarten Jan; van Herwaarden, Joost A.; Vink, Aryan; Pasterkamp, Gerard; Kluin, Jolanda; Gründeman, Paul F.

2017-01-01

OBJECTIVES: Ultra-high-molecular-weight polyethylene (UHMWPE) fibres are flexible, have high tensile strength, and platelet and bacterial adhesion is low. Therefore, UHMWPE may overcome limitations of current mechanical valves and bioprostheses. In this study, the biocompatibility and functionality

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

Science.gov (United States)

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.

Synthesis of polymer gel electrolyte with high molecular weight poly(methyl methacrylate)-clay nanocomposite

International Nuclear Information System (INIS)

Meneghetti, Paulo; Qutubuddin, Syed; Webber, Andrew

2004-01-01

Polymer nanocomposite gel electrolytes consisting of high molecular weight poly(methyl methacrylate) PMMA-clay nanocomposite, ethylene carbonate (EC)/propylene carbonate (PC) as plasticizer, and LiClO 4 electrolyte are reported. Montmorillonite clay was ion exchanged with a zwitterionic surfactant (octadecyl dimethyl betaine) and dispersed in methyl methacrylate, which was then polymerized to synthesize PMMA-clay nanocomposites. The nanocomposite was dissolved in a mixture of EC/PC with LiClO 4 , heated and pressed to obtain polymer gel electrolyte. X-ray diffraction (XRD) of the gels indicated intercalated clay structure with d-spacings of 2.85 and 1.40 nm. In the gel containing plasticizer, the clay galleries shrink suggesting intercalation rather than partial exfoliation observed in the PMMA-clay nanocomposite. Ionic conductivity varied slightly and exhibited a maximum value of 8 x 10 -4 S/cm at clay content of 1.5 wt.%. The activation energy was determined by modeling the conductivity with a Vogel-Tamman-Fulcher expression. The clay layers are primarily trapped inside the polymer matrix. Consequently, the polymer does not interact significantly with LiClO 4 electrolyte as shown by FTIR. The presence of the clay increased the glass transition temperature (Tg) of the gel as determined by differential scanning calorimetry. The PMMA nanocomposite gel electrolyte shows a stable lithium interfacial resistance over time, which is a key factor for use in electrochemical applications

Weight Penalty Incurred in Thermoelectric Recovery of Automobile Exhaust Heat

Science.gov (United States)

Rowe, D. M.; Smith, J.; Thomas, G.; Min, G.

2011-05-01

Thermoelectric recovery of automobile waste exhaust heat has been identified as having potential for reducing fuel consumption and environmentally unfriendly emissions. Around 35% of combustion energy is discharged as heat through the exhaust system, at temperatures which depend upon the engine's operation and range from 800°C to 900°C at the outlet port to less than 50°C at the tail-pipe. Beneficial reduction in fuel consumption of 5% to 10% is widely quoted in the literature. However, comparison between claims is difficult due to nonuniformity of driving conditions. In this paper the available waste exhaust heat energy produced by a 1.5 L family car when undergoing the new European drive cycle was measured and the potential thermoelectric output estimated. The work required to power the vehicle through the drive cycle was also determined and used to evaluate key parameters. This enabled an estimate to be made of the engine efficiency and additional work required by the engine to meet the load of a thermoelectric generating system. It is concluded that incorporating a thermoelectric generator would attract a penalty of around 12 W/kg. Employing thermoelectric modules fabricated from low-density material such as magnesium silicide would considerably reduce the generator weight penalty.

Flexible mechanoprosthesis made from woven ultra-high-molecular-weight polyethylene fibres: proof of concept in a chronic sheep model

NARCIS (Netherlands)

Basir, Amir; Grobben, Remco B.; Cramer, Maarten Jan; van Herwaarden, Joost A.; Vink, Aryan; Pasterkamp, Gerard; Kluin, Jolanda; Gründeman, Paul F.

2017-01-01

OBJECTIVES: Ultra-high-molecular-weight polyethylene (UHMWPE) fibres are flexible, have high tensile strength, and platelet and bacterial adhesion is low. Therefore, UHMWPE may overcome limitations of current mechanical valves and bioprostheses. In this study, the bio-compatibility and functionality

Exploring novel high power density concepts for attractive fusion systems

Energy Technology Data Exchange (ETDEWEB)

Abdou, M.A. [California State Univ., Los Angeles, CA (United States). Dept. of Mechanical Engineering; APEX Team

1999-05-01

The advanced power extraction study is aimed at exploring innovative concepts for fusion power technology (FPT) that can tremendously enhance the potential of fusion as an attractive and competitive energy source. Specifically, the study is exploring new and `revolutionary` concepts that can provide the capability to efficiently extract heat from systems with high neutron and surface heat loads while satisfying all the FPT functional requirements and maximizing reliability, maintainability, safety, and environmental requirements. The primary criteria for measuring performance of the new concepts are: (1) high power density capability with a peak neutron wall load (NWL) of {proportional_to}10 MW m{sup -2} and surface heat flux of {proportional_to}2 MW m{sup -2}; (2) high power conversion efficiency, {proportional_to}40% net; and (3) clear potential to achieve high availability; specifically low failure rate, large design margin, and short downtime for maintenance. A requirement that MTBF{>=}43 MTTR was derived as a necessary condition to achieve the required first wall/blanket availability, where MTBF is the mean time between failures and MTTR is the mean time to recover. Highlights of innovative and promising new concepts that may satisfy these criteria are provided. (orig.) 40 refs.

Type II heat-labile enterotoxins from 50 diverse Escherichia coli isolates belong almost exclusively to the LT-IIc family and may be prophage encoded.

Directory of Open Access Journals (Sweden)

Michael G Jobling

Full Text Available Some enterotoxigenic Escherichia coli (ETEC produce a type II heat-labile enterotoxin (LT-II that activates adenylate cyclase in susceptible cells but is not neutralized by antisera against cholera toxin or type I heat-labile enterotoxin (LT-I. LT-I variants encoded by plasmids in ETEC from humans and pigs have amino acid sequences that are ≥ 95% identical. In contrast, LT-II toxins are chromosomally encoded and are much more diverse. Early studies characterized LT-IIa and LT-IIb variants, but a novel LT-IIc was reported recently. Here we characterized the LT-II encoding loci from 48 additional ETEC isolates. Two encoded LT-IIa, none encoded LT-IIb, and 46 encoded highly related variants of LT-IIc. Phylogenetic analysis indicated that the predicted LT-IIc toxins encoded by these loci could be assigned to 6 subgroups. The loci corresponding to individual toxins within each subgroup had DNA sequences that were more than 99% identical. The LT-IIc subgroups appear to have arisen by multiple recombinational events between progenitor loci encoding LT-IIc1- and LT-IIc3-like variants. All loci from representative isolates encoding the LT-IIa, LT-IIb, and each subgroup of LT-IIc enterotoxins are preceded by highly-related genes that are between 80 and 93% identical to predicted phage lysozyme genes. DNA sequences immediately following the B genes differ considerably between toxin subgroups, but all are most closely related to genomic sequences found in predicted prophages. Together these data suggest that the LT-II loci are inserted into lambdoid type prophages that may or may not be infectious. These findings raise the possibility that production of LT-II enterotoxins by ETEC may be determined by phage conversion and may be activated by induction of prophage, in a manner similar to control of production of Shiga-like toxins by converting phages in isolates of enterohemmorhagic E. coli.

Separation of both fibrous and globular proteins on the basis of molecular weight using high-performance size exclusion chromatography.

Science.gov (United States)

Barden, J A

1983-11-01

A high-performance size exclusion liquid chromatographic system has been used to separate proteins with different shapes solely on the basis of their molecular weights. After the effects of ionic and hydrophobic interactions with the stationary phase have been overcome, protein elution is normally governed by their effective size in solution. Conditions are described under which proteins, with isoelectric points within the normal operating pH range of the columns, are eluted independent of their Stokes' radii. Even fibrous proteins with axial ratios of 50 elute according to their known molecular weights over the range 2000-2,000,000.

Selection of side-chain carbons in a high-molecular-weight, hydrophobic peptide using solid-state spectral editing methods

International Nuclear Information System (INIS)

Kumashiro, Kristin K.; Niemczura, Walter P.; Kim, Minna S.; Sandberg, Lawrence B.

2000-01-01

Solid-state spectral editing techniques have been used by others to simplify 13 C CPMAS spectra of small organic molecules, synthetic organic polymers, and coals. One approach utilizes experiments such as cross-polarization-with-polarization-inversion and cross-polarization-with-depolarization to generate subspectra. This work shows that this particular methodology is also applicable to natural-abundance 13 C CPMAS NMR studies of high-molecular-weight biopolymers. The editing experiments are demonstrated first with model peptides and then with α-elastin, a high-molecular-weight peptidyl preparation obtained from the elastic fibers in mammalian tissue. The latter has a predominance of small, nonpolar residues, which is evident in the crowded aliphatic region of typical 13 C CPMAS spectra. Spectral editing is particularly useful for simplifying the aliphatic region of the NMR spectrum of this elastin preparation

Sharp Absorption Peaks in THz Spectra Valuable for Crystal Quality Evaluation of Middle Molecular Weight Pharmaceuticals

Science.gov (United States)

Sasaki, Tetsuo; Sakamoto, Tomoaki; Otsuka, Makoto

2018-05-01

Middle molecular weight (MMW) pharmaceuticals (MW 400 4000) are attracting attention for their possible use in new medications. Sharp absorption peaks were observed in MMW pharmaceuticals at low temperatures by measuring with a high-resolution terahertz (THz) spectrometer. As examples, high-resolution THz spectra for amoxicillin trihydrate, atorvastatin calcium trihydrate, probucol, and α,β,γ,δ-tetrakis(1-methylpyridinium-4-yl)porphyrin p-toluenesulfonate (TMPyP) were obtained at 10 K. Typically observed as peaks with full width at half-height (FWHM) values as low as 5.639 GHz at 0.96492 THz in amoxicillin trihydrate and 8.857 GHz at 1.07974 THz for probucol, many sharp peaks of MMW pharmaceuticals could be observed. Such narrow absorption peaks enable evaluation of the crystal quality of MMW pharmaceuticals and afford sensitive detection of impurities.

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

Science.gov (United States)

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

2016-09-05

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

Radiation degradation of molasses pigment. 2. Molecular weight fraction

International Nuclear Information System (INIS)

Sawai, Teruko; Sekiguchi, Masayuki; Tanabe, Hiroko

1996-01-01

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

Evaluation of environmental degradation effects in morphology of ultra-high molecular weight polyethylene (UHMWPE) fibers

International Nuclear Information System (INIS)

Vivas, Viviane; Zylberberg, Marcel P.; Cardoso, Andre Luis V.; Pereira, Iaci M.; Weber, Ricardo P.; Suarez, Joao C. Miguez

2015-01-01

This study aims to evaluate changes in the morphology of ultra-high molecular weight polyethylene fiber (UHMWPE), before and after exposure to environmental agents. Fibers produced by two different manufacturers were analyzed. To characterize the morphology, we used the technique of small angle x-ray scattering (SAXS). The results demonstrate that the original morphology of the fibers was UHMWPE affected by the defects caused by exposure to environmental agents. (author)

High pressure size exclusion chromatography (HPSEC) determination of dissolved organic matter molecular weight revisited: Accounting for changes in stationary phases, analytical standards, and isolation methods

Science.gov (United States)

McAdams, Brandon C.; Aiken, George R.; McKnight, Diane M.; Arnold, William A.; Chin, Yu-Ping

2018-01-01

We reassessed the molecular weight of dissolved organic matter (DOM) determined by high pressure size exclusion chromatography (HPSEC) using measurements made with different columns and various generations of polystyrenesulfonate (PSS) molecular weight standards. Molecular weight measurements made with a newer generation HPSEC column and PSS standards from more recent lots are roughly 200 to 400 Da lower than initial measurements made in the early 1990s. These updated numbers match DOM molecular weights measured by colligative methods and fall within a range of values calculated from hydroxyl radical kinetics. These changes suggest improved accuracy of HPSEC molecular weight measurements that we attribute to improved accuracy of PSS standards and changes in the column packing. We also isolated DOM from wetlands in the Prairie Pothole Region (PPR) using XAD-8, a cation exchange resin, and PPL, a styrene-divinylbenzene media, and observed little difference in molecular weight and specific UV absorbance at 280 nm (SUVA280) between the two solid phase extraction resins, suggesting they capture similar DOM moieties. PPR DOM also showed lower SUVA280 at similar weights compared to DOM isolates from a global range of environments, which we attribute to oxidized sulfur in PPR DOM that would increase molecular weight without affecting SUVA280.

High Pressure Size Exclusion Chromatography (HPSEC) Determination of Dissolved Organic Matter Molecular Weight Revisited: Accounting for Changes in Stationary Phases, Analytical Standards, and Isolation Methods.

Science.gov (United States)

McAdams, Brandon C; Aiken, George R; McKnight, Diane M; Arnold, William A; Chin, Yu-Ping

2018-01-16

We reassessed the molecular weight of dissolved organic matter (DOM) determined by high pressure size exclusion chromatography (HPSEC) using measurements made with different columns and various generations of polystyrenesulfonate (PSS) molecular weight standards. Molecular weight measurements made with a newer generation HPSEC column and PSS standards from more recent lots are roughly 200 to 400 Da lower than initial measurements made in the early 1990s. These updated numbers match DOM molecular weights measured by colligative methods and fall within a range of values calculated from hydroxyl radical kinetics. These changes suggest improved accuracy of HPSEC molecular weight measurements that we attribute to improved accuracy of PSS standards and changes in the column packing. We also isolated DOM from wetlands in the Prairie Pothole Region (PPR) using XAD-8, a cation exchange resin, and PPL, a styrene-divinylbenzene media, and observed little difference in molecular weight and specific UV absorbance at 280 nm (SUVA 280 ) between the two solid phase extraction resins, suggesting they capture similar DOM moieties. PPR DOM also showed lower SUVA 280 at similar weights compared to DOM isolates from a global range of environments, which we attribute to oxidized sulfur in PPR DOM that would increase molecular weight without affecting SUVA 280 .

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

International Nuclear Information System (INIS)

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

1998-01-01

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

Glomerular sieving of high molecular weight proteins in proteinuric rats

International Nuclear Information System (INIS)

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

1987-01-01

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

Biologically labile photoproducts from riverine non-labile dissolved organic carbon in the coastal waters

Science.gov (United States)

Kasurinen, V.; Aarnos, H.; Vähätalo, A.

2015-06-01

In order to assess the production of biologically labile photoproducts (BLPs) from non-labile riverine dissolved organic carbon (DOC), we collected water samples from ten major rivers, removed labile DOC and mixed the residual non-labile DOC with artificial seawater for microbial and photochemical experiments. Bacteria grew on non-labile DOC with a growth efficiency of 11.5% (mean; range from 3.6 to 15.3%). Simulated solar radiation transformed a part of non-labile DOC into BLPs, which stimulated bacterial respiration and production, but did not change bacterial growth efficiency (BGE) compared to the non-irradiated dark controls. In the irradiated water samples, the amount of BLPs stimulating bacterial production depended on the photochemical bleaching of chromophoric dissolved organic matter (CDOM). The apparent quantum yields for BLPs supporting bacterial production ranged from 9.5 to 76 (mean 39) (μmol C mol photons-1) at 330 nm. The corresponding values for BLPs supporting bacterial respiration ranged from 57 to 1204 (mean 320) (μmol C mol photons-1). According to the calculations based on spectral apparent quantum yields and local solar radiation, the annual production of BLPs ranged from 21 (St. Lawrence) to 584 (Yangtze) mmol C m-2 yr-1 in the plumes of the examined rivers. Complete photobleaching of riverine CDOM in the coastal ocean was estimated to produce 10.7 Mt C BLPs yr-1 from the rivers examined in this study and globally 38 Mt yr-1 (15% of riverine DOC flux from all rivers), which support 4.1 Mt yr-1 of bacterial production and 33.9 Mt yr-1 bacterial respiration.

Molecular investigations on grain filling rate under terminal heat ...

African Journals Online (AJOL)

Grain yield under post anthesis high temperature stress is largely influenced by grain filling rate (GFR). To investigate molecular basis of this trait, a set of 111 recombinant inbred lines (RILs) derived from Raj 4014, a heat sensitive genotype and WH 730, heat tolerant cultivar was phenotyped during 2009-2010 and ...

High molecular weight of polysaccharides from Hericium erinaceus against amyloid beta-induced neurotoxicity.

Science.gov (United States)

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.

High Molecular Weight Glucan of the Culinary Medicinal Mushroom Agaricus bisporus is an α-Glucan that Forms Complexes with Low Molecular Weight Galactan

Directory of Open Access Journals (Sweden)

Harry J. Wichers

2010-08-01

Full Text Available An a-glucan was isolated from the culinary medicinal mushroom A. bisporus by hot water extraction, ethanol precipitation and DEAE-cellulose chromatography. The resulting material showed a single HMW peak excluded from a Sephadex G50 column that could completely be degraded by α-amylase treatment. After heating in 1% SDS a small additional peak of low MW eluted from the G50 column. The monosaccharide composition of the main peak was evaluated by HPLC, and was found to consist of a majority of glucose (97.6%, and a minor proportion of galactose (2.4%. Methylation analysis and degradation by a-amylase indicated the presence of an a-glucan with a main chain consisting of (1®4-linked units, substituted at O-6 by α-D-glucopyranose single-units in the relation 1:8. Mono- (13C-, 1H-NMR and bidimensional [1H (obs.,13C-HSQC] spectroscopy analysis confirmed the a-configuration of the Glcp residues by low frequency resonances of C-1 at d 100.6, 100.2, and 98.8 ppm and H-1 high field ones at d 5.06, 5.11, and 4.74 ppm. The DEPT-13C-NMR allowed assigning the non-substituted and O-substituted –CH2 signals at d 60.3/60.8 and 66.2 ppm, respectively. Other assignments were attributed to C-2, C-3, C-4, C-5 and C-6 of the non-reducing ends at d 71.8; 72.8; 70.0; 71.3 and 60.3/60.8 ppm, respectively. The minor proportion of galactose that was demonstrated was probably derived from a complex between the a-glucan and a low molecular weight galactan.

The ratio of high-molecular weight adiponectin and total adiponectin differs in preterm and term infants.

Science.gov (United States)

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

2009-05-01

Adiponectin consists of three subspecies (high-, middle- and low-molecular weight adiponectin). Among these, high-molecular weight adiponectin (H-adn) is suggested to be an active form of this protein. To assess the relationship between H-adn and postnatal growth in preterm infants (PIs), serum H-adn and total adiponectin (T-adn) were measured in 46 PIs at birth and at corrected term, and 26 term infants (TI) at birth. T-adn and H-adn concentrations, and the ratio of H-adn to T-adn (H/T-adn) were significantly greater in TI and PI at corrected term than in PI at birth (p adn and H-adn concentrations in PI at corrected term were similar to those in TI, but H/T-adn in PI at corrected term was less than that in TI (p adn and serum concentrations of T- and H-adn in PI at corrected term were different from those in TI. These data suggest that quality of early postnatal growth in PIs is different from that in normally developed TI. Postnatal growth accompanying adipose tissue similar to TI may be important for PI to prevent future development of cardiovascular disease.

Effects of dissolved organic matter (DOM) sources and nature of solid extraction sorbent on recoverable DOM composition: Implication into potential lability of different compound groups.

Science.gov (United States)

Chen, Meilian; Kim, Sunghwan; Park, Jae-Eun; Kim, Hyun Sik; Hur, Jin

2016-07-01

Noting the source-dependent properties of dissolved organic matter (DOM), this study explored the recoverable compounds by solid phase extraction (SPE) of two common sorbents (C18 and PPL) eluted with methanol solvent for contrasting DOM sources via fluorescence excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Fresh algae and leaf litter extracts DOM, one riverine DOM, and one upstream lacustrine DOM were selected for the comparison. C18 sorbent was generally found to extract more diverse molecular formula, relatively higher molecular weight, and more heteroatomic DOM compounds within the studied mass range than PPL sorbent except for the leaf litter extract. Even with the same sorbent, the main molecular features of the two end member DOM were distributed on different sides of the axes of a multivariate ordination, indicating the source-dependent characteristics of the recoverable compounds by the sorbents. In addition, further examination of the molecular formula uniquely present in the two end members and the upstream lake DOM suggested that proteinaceous, tannin-like, and heteroatomic DOM constituents might be potential compound groups which are labile and easily degraded during their mobilization into downstream watershed. This study provides new insights into the sorbent selectivity of DOM from diverse sources and potential lability of various compound groups.

Lability of Nanoparticulate Metal Complexes at a Macroscopic Metal Responsive (Bio)interface

NARCIS (Netherlands)

Duval, Jérôme F.L.; Town, Raewyn M.; Leeuwen, Van Herman P.

2018-01-01

The lability of metal complexes expresses the extent of the dissociative contribution of the complex species to the flux of metal ions toward a macroscopic metal-responsive (bio)interface, for example, an electrodic sensor or an organism. While the case of molecular ligands is well-established, it

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

Science.gov (United States)

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

2016-08-23

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

Preclinical studies of lymphographic applilcation of 99mTc-dextrans of different molecular weight

International Nuclear Information System (INIS)

Lamka, J.; Kvetina, J.; Kafka, P.

1986-01-01

In a preclinical investigation on rabbits the distribution was tested of dextrans of two molecular weights (40,000 and 70,000) with regard to their use as a carrier in indirect lymphography. The tests showed that both 99m Tc-dextrans achieve high ratios of lymph/blood levels. It is suggested that for clinical work it is better to use dextran with a molecular weight of 70,000 than that with a molecular weight of 40,000. (author)

Purification of two high molecular weight proteases from rabbit reticulocyte lysate

International Nuclear Information System (INIS)

Hough, R.; Pratt, G.; Rechsteiner, M.

1987-01-01

The authors have purified two large proteases from rabbit reticulocyte lysate. The enzymes are so similar in their chromatographic behavior that each is the only significant contaminant of the other during the final stages of purification. At pH 7.8, both hydrolyze 125 I-α-casein and 4-methylcoumaryl-7-amide (MCA) derivatives with tyrosine, phenylalanine or arginine at the P 1 position. The larger, ATP-dependent enzyme degrades ubiquitin-lysozyme conjugates, but it does not degrade unmodified lysozyme. Hydrolysis of Suc-Leu-Leu-Val-Tyr-MCA by this enzyme is also stimulated two-fold in the presence of ATP. The protease has a molecular weight of 950,000 based on sedimentation, gel filtration and non-denaturing PAGE. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the protease is composed of a number of subunits with molecular masses between 32 and 110 kDa. Densitometric analysis showed equivalent amounts of the two larger chains, and the presence of one copy of each in the native enzyme would be consistent with an M/sub r/ of 950,000. The smaller protease has a molecular weight of 700,000 and is composed of 8 to 10 subunits ranging from 21,000 to 32,000. It cleaves ubiquitin-lysozyme conjugates only slightly, and hydrolysis of conjugates or fluorogenic peptide substrates is not stimulated by ATP. This protease appears similar, if not identical, to the multicatalytic protease complex first purified by Wilk and Orlowski

Effect of Molecular Weight on the Properties of Liquid Epoxidized Natural Rubber Acrylate (LENRA)/ Silica Hybrid Composites

International Nuclear Information System (INIS)

Eda Yuhana Ariffin; Azizan Ahmad; Dahlan Mohd; Mahathir Mohamed

2011-01-01

This paper reports on the effect of molecular weight on the morphological and mechanical properties of liquid epoxidized natural rubber acrylate (LENRA)/ silica hybrid composites prepared by sol-gel technique. The sol-gel reaction was conducted at different concentration of tetraethyl orthosilicate (TEOS), used as a precursor of silica. TEOS were introduced in 10, 20, 30, 40 and 50 parts per hundred rubber (phr) in the composites. Two different molecular weights of ENR were used to study the effect of molecular weight on the mechanical and morphological properties of the compounds. These compounds were cured by ultraviolet (UV) irradiation. The mechanical properties were studied through pendulum hardness and scratch tests. Higher molecular weight of ENR showed better mechanical properties than lower molecular weight. Transmission electron microscope was used to determine the silica size and to study the distribution and dispersion of the silica particles. High molecular weight showed greater distribution and dispersion of silica particles with diameter of 13 - 256 nm. Morphological and mechanical properties of LENRA/ silica hybrid composites were improved by using high molecular weight of ENR. (author)

High Molecular Weight Isoforms of Growth Hormone In Cells of the Immune System

Science.gov (United States)

Weigent, Douglas A.

2013-01-01

A substantial body of research exists to support the idea that cells of the immune system produce growth hormone (GH). However, the structure and mechanism of action of lymphocyte-derived GH continues to remain largely unknown. Here we present the results of Western analysis of whole cell extracts showing that different molecular weight isoforms of GH of approximately 100 kDa, 65 kDa, and 48 kDa can be detected in primary mouse cells of the immune system and in the mouse EL4 cell line. The identity of the 65 kDa and 48 kDa isoforms of GH were confirmed by mass spectrometry. The various isoforms were detected in both enriched T and B spleen cell populations. The large molecular weight isoform appears to reside primarily in the cytoplasm whereas the lower molecular weight 65 kDa and 48 kDa isoforms were detected primarily in the nucleus. These results also suggest that GH isoforms are induced by oxidative stress. In EL4 cells overexpressing GH, the expression of luciferase controlled by a promoter containing the antioxidant response element is increased almost three-fold above control. The data suggest that the induction of isoforms of the GH molecule in cells of the immune system may be an important mechanism of adaptation and/or protection of lymphoid cells under conditions of oxidative stress. PMID:21741628

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

OpenAIRE

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

2013-01-01

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

Perceptual attraction in tool use: evidence for a reliability-based weighting mechanism.

Science.gov (United States)

Debats, Nienke B; Ernst, Marc O; Heuer, Herbert

2017-04-01

Humans are well able to operate tools whereby their hand movement is linked, via a kinematic transformation, to a spatially distant object moving in a separate plane of motion. An everyday example is controlling a cursor on a computer monitor. Despite these separate reference frames, the perceived positions of the hand and the object were found to be biased toward each other. We propose that this perceptual attraction is based on the principles by which the brain integrates redundant sensory information of single objects or events, known as optimal multisensory integration. That is, 1 ) sensory information about the hand and the tool are weighted according to their relative reliability (i.e., inverse variances), and 2 ) the unisensory reliabilities sum up in the integrated estimate. We assessed whether perceptual attraction is consistent with optimal multisensory integration model predictions. We used a cursor-control tool-use task in which we manipulated the relative reliability of the unisensory hand and cursor position estimates. The perceptual biases shifted according to these relative reliabilities, with an additional bias due to contextual factors that were present in experiment 1 but not in experiment 2 The biased position judgments' variances were, however, systematically larger than the predicted optimal variances. Our findings suggest that the perceptual attraction in tool use results from a reliability-based weighting mechanism similar to optimal multisensory integration, but that certain boundary conditions for optimality might not be satisfied. NEW & NOTEWORTHY Kinematic tool use is associated with a perceptual attraction between the spatially separated hand and the effective part of the tool. We provide a formal account for this phenomenon, thereby showing that the process behind it is similar to optimal integration of sensory information relating to single objects. Copyright © 2017 the American Physiological Society.

The effect of monomer molecular weight on grafting reaction

International Nuclear Information System (INIS)

Wu Minghong; Ding Zhongli; Ma Zueteh

1995-01-01

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

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

International Nuclear Information System (INIS)

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

1976-01-01

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

How does the preparation of rye porridge affect molecular weight distribution of extractable dietary fibers?

Science.gov (United States)

Rakha, Allah; Aman, Per; Andersson, Roger

2011-01-01

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

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

Directory of Open Access Journals (Sweden)

Roger Andersson

2011-05-01

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

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

Science.gov (United States)

Izunobi, Josephat U.; Higginbotham, Clement L.

2011-01-01

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

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

Science.gov (United States)

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

2017-01-20

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

Effect of inorganic and organic copper fertilizers on copper nutrition in Spinacia oleracea and on labile copper in soil.

Science.gov (United States)

Obrador, Ana; Gonzalez, Demetrio; Alvarez, Jose M

2013-05-22

To ensure an optimal concentration of Cu in food crops, the effectiveness of eight liquid Cu fertilizers was studied in a spinach ( Spinacia oleracea L.) crop grown on Cu-deficient soil under greenhouse conditions. Plant dry matter yields, Cu concentrations in spinach plants (total and morpholino acid (MES)- and ethylenediaminedisuccinic acid (EDDS)-extractable), and Cu uptakes were studied. The behavior of Cu in soil was evaluated by both single and sequential extraction procedures. The highest quantities of Cu in labile forms in the soil, total uptakes, and Cu concentrations in the plants were associated with the application of the two sources that contained Cu chelated by EDTA and/or DTPA. The fertilizers containing these Cu chelates represent a promising approach to achieve high levels of agronomic biofortification. The stronger correlations obtained between low-molecular-weight organic acid-extractable Cu in soil and the Cu concentrations and Cu uptakes by the plants show the suitability of this soil extraction method for predicting Cu available to spinach plants.

Relationship between molecular weight, monosaccharide composition and immunobiologic activity of Astragalus polysaccharides.

Science.gov (United States)

Jiang, Yiping; Qi, Xiaohui; Gao, Kai; Liu, Wenjun; Li, Na; Cheng, Ningbo; Ding, Gang; Huang, Wenzhe; Wang, Zhenzhong; Xiao, Wei

2016-10-01

Four Astragalus polysaccharides (APS1-APS4) were isolated from the water extract of Radix Astragali and purified through ethanol precipitation with 20 %, 40 %, 60 % and 80 % ethanol, respectively. The total sugar content was measured by sulfuric acid-phenol method. Their molecular weight was determined using high performance gel permeation chromatography (HPGPC) and their monosaccharide composition was analyzed by reversed-phase high performance liquid chromatography (HPLC) after pre-column derivatization. Then the immunobiologic activity of APS was evaluated by the experiment of spleen lymphocytes proliferation in vitro. The data suggested that precipitation by different concentration of ethanol will obtain different molecular weight APS, the higher concentration of ethanol the smaller molecular weight for APS. The molecular weights of four APS were 257.7 kDa, 40.1 kDa, 15.3 kDa and 3.2 kDa. Monosaccharide composition analysis indicated that APS1 consisted of glucose only, and APS2 all consisted of arabinose. APS3 consisted of rhamnose, glucose, galactose and arabinose and APS4 consisted of galactose and arabinose, in a molar ratio of 1:10.76:6.55:12 and 3.02:1. The result of immunobiologic activity assay showed that both APS2 and APS3 can effectively stimulate normal spleen lymphocyte proliferation in vitro. Apart from this, the effect of APS2 also showed dose dependent tendency from 6.25 μg/mL to 800 μg/mL. The result of this research indicated that Astragalus polysaccharides, which consist of arabinose and their molecular weight between 15.2 kDa to 40.1 kDa, neither too high nor too low, had significant immune activity.

Molecular weight distribution of electron and γ-ray irradiated PEEK measured by very high temperature GPC

International Nuclear Information System (INIS)

Nakahara, H.

1996-01-01

Poly(ether ether ketone)(PEEK) films were irradiated with electron beam in air and in helium. Gel fractions of the PEEK samples were determined as the ratio of the weight of insoluble fraction/total weigh by extracting the samples with 1-chloronaphthalene (1-CN) at 260degC. While unirradiated PEEK samples were dissolved in 1-CN completely, PEEK samples highly (10 - 50 MGy) irradiated in air were almost insoluble in the solvent. The weight-average molecular weight M w of soluble fractions of the samples were measured by very high temperature gel permeation chromatography (VHTGPC): it was found that the M w decreases with increasing dose. On the other hand, PEEK samples irradiated in helium gave gel fractions at lower doses (0 - 5 MGy) than in air. The PEEK films were also irradiated with 60 Co γ-rays in the dose range, i.e. from 0 to 5 MGy. The γ-irradiated PEEK samples were completely dissolved in 1-CN at 260degC. Their M w measured by VHTGPC decreases with increasing dose. (author)

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

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A.M. Al-Sabagh

2013-12-01

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

DNA lability induced by nimustine and ramustine in rat glioma cells.

Science.gov (United States)

Mineura, K; Fushimi, S; Itoh, Y; Kowada, M

1988-01-01

The DNA labile sites induced by two nitrosoureas, nimustine (ACNU) and ramustine (MCNU) synthesised in Japan, have been examined in highly reiterated DNA sequences of rat glioma cells. Reiterated fragments of 167 and 203 base pairs (bp), obtained after Hind III and Hae III restriction endonuclease digestion of rat glioma cells DNA, were used as target DNA sequences to determine the labile sites. In vitro reaction with ACNU and MCNU resulted in scission products corresponding to the locations of guanine. Subsequent piperidine hydrolysis produced more frequent breaks of the phosphodiester bonds at guanine positions, thus forming alkali-labile sites. Images PMID:3236017

An anaerobic incubation study of metal lability in drinking water treatment residue with implications for practical reuse.

Science.gov (United States)

Wang, Changhui; Yuan, Nannan; Pei, Yuansheng

2014-06-15

Drinking water treatment residue (WTR) is an inevitable by-product generated during the treatment of drinking water with coagulating agents. The beneficial reuse of WTR as an amendment for environmental remediation has attracted growing interest. In this work, we investigated the lability of Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sr, V and Zn in Fe/Al hydroxide-comprised WTR based on a 180-day anaerobic incubation test using fractionation, in vitro digestion and a toxicity characteristic leaching procedure. The results indicated that most metals in the WTR were stable during anaerobic incubation and that the WTR before and after incubation could be considered non-hazardous in terms of leachable metal contents according to US EPA Method 1311. However, the lability of certain metals in the WTR after incubation increased substantially, especially Mn, which may be due to the reduction effect. Therefore, although there is no evidence presented to restrict the use of WTR in the field, the lability of metals (especially Mn) in WTR requires further assessment prior to field application. In addition, fractionation (e.g., BCR) is recommended for use to determine the potential lability of metals under various conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

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

Science.gov (United States)

Panin, S. V.; Kornienko, L. A.; Alexenko, V. O.; Buslovich, D. G.; Dontsov, Yu. V.

2017-12-01

Mechanical and tribotechnical characteristics of polymer-polymeric composites of UHMWPE are studied with the aim of developing extrudable, wear-resistant, self-lubricant polymer mixtures for Additive Manufacturing (AM). The motivation of the study is their further application as feedstocks for 3D printing. Blends of UHMWPE with graft- and block copolymers of low-density polyethylene (HDPE-g-VTMS, HDPE-g-SMA, HDPE-b-EVA), polypropylene (PP), block copolymers of polypropylene and polyamide with linear low density polyethylene (PP-b-LLDPE, PA-b-LLDPE), as well as cross-linked polyethylene (PEX-b), are examined. The choice of compatible polymer components for an ultra- high molecular weight matrix for increasing processability (extrudability) is motivated by the search for commercially available and efficient additives aimed at developing wear-resistant extrudable polymer composites for additive manufacturing. The extrudability, mechanical properties and wear resistance of UHMWPE-based polymer-polymeric composites under sliding friction with different velocities and loads are studied.

The influence of gamma radiation on the molecular weight and glass transition of PLLA and HAp/PLLA nanocomposite

International Nuclear Information System (INIS)

Milicevic, D.; Trifunovic, S.; Dojcilovic, J.; Ignjatovic, N.; Suljovrujic, E.

2010-01-01

The influence of gamma radiation on the molecular weight and glass transition behaviour of poly-L-lactide (PLLA) and hydroxyapatite/poly-L-lactide (HAp/PLLA) nanocomposite has been studied. Since PLLA exposed to high-energy radiation in the presence of air is prone to chain scission reactions and large degradation, changes in molecular weight were obtained by gel permeation chromatography (GPC). Alterations in the glass transition behaviour were investigated by differential scanning calorimetry (DSC). The apparent activation energy (ΔH*) for glass transition was determined on the basis of the heating rate dependence of the glass transition temperature (T g ). Our findings support the fact that chain scission is the main reason for the decrease of T g and ΔH* with the absorbed dose. Furthermore, more intensive chain scission degradation of PLLA was observed in HAp/PLLA and can only be ascribed to the presence of HAp nanoparticles. Consequently, initial differences in the glass transition temperature and/or apparent activation energy of PLLA and HAp/PLLA became more pronounced with absorbed dose. This study reveals that radiation-induced changes in molecular weight and glass transition temperature occur in a predictable and fairly accurate manner. Therefore, gamma radiation can be used not only for sterilization but also for tailoring desirable end-use properties of these biomaterials.

Enhancement of human adaptive immune responses by administration of a high-molecular-weight polysaccharide extract from the cyanobacterium Arthrospira platensis

DEFF Research Database (Denmark)

Pedersen, Morten Løbner; Walsted, Anette; Larsen, Rune

2008-01-01

The effect of consumption of Immulina, a high-molecular-weight polysaccharide extract from the cyanobacterium Arthrospira platensis, on adaptive immune responses was investigated by evaluation of changes in leukocyte responsiveness to two foreign recall antigens, Candida albicans (CA) and tetanus...

High temperature nuclear process heat systems for chemical processes

International Nuclear Information System (INIS)

Jiacoletti, R.J.

1976-01-01

The development planning and status of the very high temperature gas cooled reactor as a source of industrial process heat is presented. The dwindling domestic reserves of petroleum and natural gas dictate major increases in the utilization of coal and nuclear sources to meet the national energy demand. The nuclear process heat system offers a unique combination of the two that is environmentally and economically attractive and technically sound. Conceptual studies of several energy-intensive processes coupled to a nuclear heat source are presented

Information filtering via weighted heat conduction algorithm

Science.gov (United States)

Liu, Jian-Guo; Guo, Qiang; Zhang, Yi-Cheng

2011-06-01

In this paper, by taking into account effects of the user and object correlations on a heat conduction (HC) algorithm, a weighted heat conduction (WHC) algorithm is presented. We argue that the edge weight of the user-object bipartite network should be embedded into the HC algorithm to measure the object similarity. The numerical results indicate that both the accuracy and diversity could be improved greatly compared with the standard HC algorithm and the optimal values reached simultaneously. On the Movielens and Netflix datasets, the algorithmic accuracy, measured by the average ranking score, can be improved by 39.7% and 56.1% in the optimal case, respectively, and the diversity could reach 0.9587 and 0.9317 when the recommendation list equals to 5. Further statistical analysis indicates that, in the optimal case, the distributions of the edge weight are changed to the Poisson form, which may be the reason why HC algorithm performance could be improved. This work highlights the effect of edge weight on a personalized recommendation study, which maybe an important factor affecting personalized recommendation performance.

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

Science.gov (United States)

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

Boosting spin-caloritronic effects by attractive correlations in molecular junctions.

Science.gov (United States)

Weymann, Ireneusz

2016-01-25

In nanoscopic systems quantum confinement and interference can lead to an enhancement of thermoelectric properties as compared to conventional bulk materials. For nanostructures, such as molecules or quantum dots coupled to external leads, the thermoelectric figure of merit can reach or even exceed unity. Moreover, in the presence of external magnetic field or when the leads are ferromagnetic, an applied temperature gradient can generate a spin voltage and an associated spin current flow in the system, which makes such nanostructures particularly interesting for future thermoelectric applications. In this study, by using the numerical renormalization group method, we examine the spin-dependent thermoelectric transport properties of a molecular junction involving an orbital level with attractive Coulomb correlations coupled to ferromagnetic leads. We analyze how attractive correlations affect the spin-resolved transport properties of the system and find a nontrivial dependence of the conductance and tunnel magnetoresistance on the strength and sign of those correlations. We also demonstrate that attractive correlations can lead to an enhancement of the spin thermopower and the figure of merit, which can be controlled by a gate voltage.

High molecular weight FGF2 isoforms demonstrate canonical receptor-mediated activity and support human embryonic stem cell self-renewal

Directory of Open Access Journals (Sweden)

Denis Kole

2017-05-01

Full Text Available Basic fibroblast growth factor (FGF2 is a highly pleiotropic member of a large family of growth factors with a broad range of activities, including mitogenesis and angiogenesis (Ornitz et al., 1996; Zhang et al., 2006, and it is known to be essential for maintenance of balance between survival, proliferation, and self-renewal in human pluripotent stem cells (Eiselleova et al., 2009; Zoumaro-Djayoon et al., 2011. A single FGF2 transcript can be translated into five FGF2 protein isoforms, an 18 kDa low molecular weight (LMW isoform and four larger high molecular weight (HMW isoforms (Arese et al., 1999; Arnaud et al., 1999. As they are not generally secreted, high molecular weight (HMW FGF2 isoforms have predominantly been investigated intracellularly; only a very limited number of studies have investigated their activity as extracellular factors. Here we report over-expression, isolation, and biological activity of all recombinant human FGF2 isoforms. We show that HMW FGF2 isoforms can support self-renewal of human embryonic stem cells (hESCs in vitro. Exogenous supplementation with HMW FGF2 isoforms also activates the canonical FGFR/MAPK pathway and induces mitogenic activity in a manner similar to that of the 18 kDa FGF2 isoform. Though all HMW isoforms, when supplemented exogenously, are able to recapitulate LMW FGF2 activity to some degree, it appears that certain isoforms tend to do so more poorly, demonstrating a lesser functional response by several measures. A better understanding of isoform-specific FGF2 effects will lead to a better understanding of developmental and pathological FGF2 signaling.

Chemical modification of high molecular weight polyethylene through gamma radiation for biomaterials applications; Modificacao quimica de polietileno de alto peso molecular atraves de radiacao gama para aplicacao em biomateriais

Energy Technology Data Exchange (ETDEWEB)

Raposo, Matheus P.; Rocha, Marisa C.G., E-mail: matheusmerlim@hotmail.com [Universidade Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Instituto Politecnico

2015-07-01

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

Microbial control of soil organic matter mineralization responses to labile carbon in subarctic climate change treatments

DEFF Research Database (Denmark)

Rousk, Kathrin; Michelsen, Anders; Rousk, Johannes

2016-01-01

Half the global soil carbon (C) is held in high-latitude systems. Climate change will expose these to warming and a shift towards plant communities with more labile C input. Labile C can also increase the rate of loss of native soil organic matter (SOM); a phenomenon termed ‘priming’. We investig......Half the global soil carbon (C) is held in high-latitude systems. Climate change will expose these to warming and a shift towards plant communities with more labile C input. Labile C can also increase the rate of loss of native soil organic matter (SOM); a phenomenon termed ‘priming’. We...

Prokaryotic degradation of high molecular weight dissolved organic matter in the deep-sea waters of NW Mediterranean Sea under in situ temperature and pressure conditions during contrasted hydrological conditions

Science.gov (United States)

Tamburini, C.; Boutrif, M.; Garel, M.; Sempéré, R.; Repeta, D.; Charriere, B.; Nerini, D.; Panagiotopoulos, C.

2016-02-01

The contribution of the semi-labile dissolved organic carbon (DOC) to the global prokaryotic production has been assessed in very few previous studies. Some experiments show rapid utilization of semi-reactive DOC by prokaryotes, while other experiments show almost no utilization at all. However, all these studies did not take into account the role of hydrostatic pressure for the degradation of organic matter. In this study, we investigate (1) the degradation of "natural" high molecular weight DOM HMW-DOM (obtained after ultrafiltration) and (2) the uptake of labeled extracellular polymeric substances (3H-EPS) incubated with deep-sea water samples (2000 m-depth, NW Mediterranean Sea) under in situ pressure conditions (HP) and under atmospheric compression after decompression of the deep samples (ATM) during stratified and mixed water conditions (deep sea convection). Our results indicated that during HP incubations DOC exhibited the highest degradation rates (kHP DOC = 0.82 d-1) compared to the ATM conditions were no or few degradation was observed (kATM DOC= 0.007 d-1). An opposite trend was observed for the HP incubations from mixed deep water masses. HP incubation measurements displayed the lowest DOC degradation (kHP DOC=0.031 d-1) compared to the ATM conditions (kATM DOC=0.62 d-1). These results imply the presence of allochthonous prokaryotic cells in deep-sea samples after a winter water mass convection. Same trends were found using 3H-EPS uptake rates which were higher at HP than at ATM conditions during stratified period conditions whereas the opposite patterns were observed during deep-sea convection event. Moreover, we found than Euryarchaea were the main contributors to 3H-EPS assimilation at 2000m-depth, representing 58% of the total cells actively assimilating 3H-EPS. This study demonstrates that remineralization rates of semi-labile DOC in deep NW Med. Sea are controlled by the prokaryotic communities, which are influenced by the hydrological

Adiabatic Cooling for Rovibrational Spectroscopy of Molecular Ions

DEFF Research Database (Denmark)

Fisher, Karin

2017-01-01

The field of cold molecular ions is a fast growing one, with applications in high resolution spectroscopy and metrology, the search for time variations of fundamental constants, cold chemistry and collisions, and quantum information processing, to name a few. The study of single molecular ions...... is attractive as it enables one to push the limits of spectroscopic accuracy. Non-destructive spectroscopic detection of molecular ions can be achieved by co-trapping with an easier to detect atomic ion. The ion chain has coupled motion, and transitions which change both the internal and motional states...... to the measured heating rates, almost perfectly fitting existing heating rate theory. Further, the same model successfully predicted the heating rates of the in-phase mode of a two-ion crystal, indicating that we can use it to predict the heating rates in experiments on molecule-atom chains. Adiabatic cooling...

High temperature and high resolution uv photoelectron spectroscopy using supersonic molecular beams

International Nuclear Information System (INIS)

Wang, Lai-Sheng; Reutt-Robey, J.E.; Niu, B.; Lee, Y.T.; Shirley, D.A.

1989-07-01

A high temperature molecular beam source with electron bombardment heating has been built for high resolution photoelectron spectroscopic studies of high temperature species and clusters. This source has the advantages of: producing an intense, continuous, seeded molecular beam, eliminating the interference of the heating mechanism from the photoelectron measurement. Coupling the source with our hemispherical electron energy analyzer, we can obtain very high resolution HeIα (584 angstrom) photoelectron spectra of high temperature species. Vibrationally-resolved photoelectron spectra of PbSe, As 2 , As 4 , and ZnCl 2 are shown to demonstrate the performance of the new source. 25 refs., 8 figs., 1 tab

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

Science.gov (United States)

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

2013-12-28

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

Ballistic behavior of ultra-high molecular weight polyethylene composite: effect of gamma radiation

International Nuclear Information System (INIS)

Alves, Andreia L. dos Santos; Nascimento, Lucio F.C.; Suarez, Joao C. Miguez; lucio2002bol.com.br

2003-01-01

Since World War II, textile composites have been used as ballistic armor. Ultra-high molecular weight polyethylene (UHMWPE) fibers are used in the production of armor materials. As they have been developed and commercialized only recently, there is not enough information about the effect of environmental agents in the ballistic performance of UHMWPE composites. In the present work, was evaluated the ballistic behavior of composite plates manufactured with UHMWPE fibers after exposure to gamma radiation. The ballistic tests results were related to the macromolecular alterations induced by the radiation through mechanical (hardness, impact and flexure) and physicochemical (Ftir/Mir. DSC and TGA) testing. It was observed that irradiation induces changes in the UHMWPE, degrading the ballistic performance of the composite. These results are presented and discussed. (author)

Sustained High Levels of Both Total and High Molecular Weight Adiponectin in Plasma during the Convalescent Phase of Haemorrhagic Fever with Renal Syndrome Are Associated with Disease Severity

Directory of Open Access Journals (Sweden)

Kang Tang

2017-01-01

Full Text Available Haemorrhagic fever with renal syndrome (HFRS is characterised by an uncontrolled immune response that causes vascular leakage. Adiponectin (APN is an adipocytokine involved in prorevascularisation and immunomodulation. To investigate the possible effects of APN in the pathogenesis of HFRS, total and high molecular weight (HMW APN levels in the plasma of patients with HFRS were quantified using enzyme-linked immunosorbent assay (ELISA. Compared with those in healthy controls, the plasma total and HMW APN levels in patients were elevated to different degrees from the fever onset and remained high at the convalescent phase. Consistent with these results, western blot analysis additionally showed that low molecular weight (LMW, middle molecular weight (MMW, and HMW APN levels were all elevated and contributed to the elevation of the total APN level. Importantly, sustained high levels of total and HMW APN at the convalescent phase were significantly higher in patients with critical disease than those in patients with mild or moderate disease. Moreover, total and HMW APN levels negatively correlated with white blood cell count and positively correlated with platelet count and serum albumin level. These results may provide insights into understanding the roles of total and HMW APN in the pathogenesis of HFRS.

Rapid Analysis of Apolar Low Molecular Weight Constituents in Wood Using High Pressure Liquid Chromatography with Evaporative Light Scattering Detection

NARCIS (Netherlands)

Claassen, F.W.; Haar, van de C.; Beek, van T.A.; Dorado, J.; Martinez-Inigo, M.; Sierra-Alvarez, R.

2000-01-01

A new high pressure liquid chromatographic method with evaporative light scattering detection was developed for the qualitative and quantitative analysis of apolar, low molecular weight constituents in wood. The wood extractives were obtained by means of a 6 h Soxhlet extraction with acetone. The

Childhood Maltreatment, Emotional Lability, and Alcohol Problems in Young Adults At-Risk for ADHD: Testing Moderation and Moderated Moderation.

Science.gov (United States)

Bunford, Nóra; Wymbs, Brian T; Dawson, Anne E; Shorey, Ryan C

2017-01-01

Childhood maltreatment and alcohol problems are common among young adults with attention-deficit hyperactivity disorder (ADHD). However, little is known about the degree to which maltreatment and alcohol problems are associated; potential pertinent mediating or moderating mechanisms, such as emotional lability; and whether this association varies by sex. We examined, in a sample of adults at risk for ADHD (N = 122, 37% male), the association between childhood maltreatment and alcohol problems, whether emotional lability mediated or moderated this association, and whether either role of emotional lability differed between men and women. Emotional lability moderated the association between emotional neglect and alcohol problems; maltreatment increased risk for alcohol problems for those scoring high tovery high on emotional lability, but not for those with very low-moderate levels. The association between emotional abuse and alcohol problems depended both on emotional lability and sex; emotional abuse decreased the risk for alcohol problems among men very low/low on emotional lability, but not for men who were moderate to very high on emotional lability, or for women. These findings have implications for the way in which targeting maltreatment and emotional lability may be incorporated into prevention and intervention programs to prevent alcohol problems among men and women at risk for ADHD.

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

Science.gov (United States)

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.

Properties of crosslinked ultra-high-molecular-weight polyethylene.

Science.gov (United States)

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.

Thermal Inactivation Kinetics and Secondary Structure Change of a Low Molecular Weight Halostable Exoglucanase from a Marine Aspergillus niger at High Salinities.

Science.gov (United States)

Xue, Dong-Sheng; Liang, Long-Yuan; Lin, Dong-Qiang; Yao, Shan-Jing

2017-11-01

Two kinds of exoglucanase were purified from a marine Aspergillus niger. Catalytic ability of halophilic exoglucanase with a lower molecular weight and secondary structure change was analyzed at different salinities. Activity of the low molecular weight exoglucanase in 10% NaCl solution (w/v) was 1.69-fold higher of that in NaCl-free solution. Half-life time in 10% NaCl solution (w/v) was over 1.27-fold longer of that in NaCl-free solution. Free energy change of the low molecular weight exoglucanase denaturation, △G, in 10% NaCl solution (w/v) was 0.54 kJ/mol more than that in NaCl-free solution. Melt point in 10% NaCl solution (w/v), 52.01 °C, was 4.21 °C higher than that in NaCl-free solution, 47.80 °C. K m value, 0.179 mg/ml in 10% NaCl solution (w/v) was less 0.044 mg/ml than that, 0.224 mg/ml, in NaCl-free solution. High salinity made content of α-helix increased. Secondary structure change caused by high salinities improved exoglucanase thermostability and catalysis activity. The halophilic exoglucanase from a marine A. niger was valuable for hydrolyzing cellulose at high salinities.

Proton transport properties of poly(aspartic acid) with different average molecular weights

Energy Technology Data Exchange (ETDEWEB)

Nagao, Yuki, E-mail: ynagao@kuchem.kyoto-u.ac.j [Department of Mechanical Systems and Design, Graduate School of Engineering, Tohoku University, 6-6-01 Aoba Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Imai, Yuzuru [Institute of Development, Aging and Cancer (IDAC), Tohoku University, 4-1 Seiryo-cho, Aoba-ku, Sendai 980-8575 (Japan); Matsui, Jun [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Sendai 980-8577 (Japan); Ogawa, Tomoyuki [Department of Electronic Engineering, Graduate School of Engineering, Tohoku University, 6-6-05 Aoba Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Miyashita, Tokuji [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Sendai 980-8577 (Japan)

2011-04-15

Research highlights: Seven polymers with different average molecular weights were synthesized. The proton conductivity depended on the number-average degree of polymerization. The difference of the proton conductivities was more than one order of magnitude. The number-average molecular weight contributed to the stability of the polymer. - Abstract: We synthesized seven partially protonated poly(aspartic acids)/sodium polyaspartates (P-Asp) with different average molecular weights to study their proton transport properties. The number-average degree of polymerization (DP) for each P-Asp was 30 (P-Asp30), 115 (P-Asp115), 140 (P-Asp140), 160 (P-Asp160), 185 (P-Asp185), 205 (P-Asp205), and 250 (P-Asp250). The proton conductivity depended on the number-average DP. The maximum and minimum proton conductivities under a relative humidity of 70% and 298 K were 1.7 . 10{sup -3} S cm{sup -1} (P-Asp140) and 4.6 . 10{sup -4} S cm{sup -1} (P-Asp250), respectively. Differential thermogravimetric analysis (TG-DTA) was carried out for each P-Asp. The results were classified into two categories. One exhibited two endothermic peaks between t = (270 and 300) {sup o}C, the other exhibited only one peak. The P-Asp group with two endothermic peaks exhibited high proton conductivity. The high proton conductivity is related to the stability of the polymer. The number-average molecular weight also contributed to the stability of the polymer.

Rotavirus 2/6 Viruslike Particles Administered Intranasally with Cholera Toxin, Escherichia coli Heat-Labile Toxin (LT), and LT-R192G Induce Protection from Rotavirus Challenge

OpenAIRE

O’Neal, Christine M.; Clements, John D.; Estes, Mary K.; Conner, Margaret E.

1998-01-01

We have shown that rotavirus 2/6 viruslike particles composed of proteins VP2 and VP6 (2/6-VLPs) administered to mice intranasally with cholera toxin (CT) induced protection from rotavirus challenge, as measured by virus shedding. Since it is unclear if CT will be approved for human use, we evaluated the adjuvanticity of Escherichia coli heat-labile toxin (LT) and LT-R192G. Mice were inoculated intranasally with 10 μg of 2/6-VLPs combined with CT, LT, or LT-R192G. All three adjuvants induced ...

The measurement of the molecular weight of humic acid by ultracentrifugation

International Nuclear Information System (INIS)

Gardner, M.P.

1989-07-01

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

Laser surface modification of ultra-high-molecular-weight polyethylene (UHMWPE) for biomedical applications

International Nuclear Information System (INIS)

Riveiro, A.; Soto, R.; Val, J. del; Comesaña, R.; Boutinguiza, M.; Quintero, F.; Lusquiños, F.; Pou, J.

2014-01-01

Ultra-high-molecular-weight polyethylene (UHMWPE) is a synthetic polymer used for biomedical applications because of its high impact resistance, ductility and stability in contact with physiological fluids. Therefore, this material is being used in human orthopedic implants such as total hip or knee replacements. Surface modification of this material relates to changes on its chemistry, microstructure, roughness, and topography, all influencing its biological response. Surface treatment of UHMWPE is very difficult due to its high melt viscosity. This work presents a systematic approach to discern the role of different laser wavelengths (λ = 1064, 532, and 355 nm) on the surface modification of carbon coated UHMWPE samples. Influence of laser processing conditions (irradiance, pulse frequency, scanning speed, and spot overlapping) on the surface properties of this material was determined using an advanced statistical planning of experiments. A full factorial design of experiments was used to find the main effects of the processing parameters. The obtained results indicate the way to maximize surface properties which largely influence cell–material interaction.

Laser surface modification of ultra-high-molecular-weight polyethylene (UHMWPE) for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Riveiro, A., E-mail: ariveiro@uvigo.es [Applied Physics Department, University of Vigo, ETSII, Lagoas-Marcosende, 9, Vigo 36310 (Spain); Centro Universitario de la Defensa, Escuela Naval Militar, Plaza de España 2, 36920 Marín (Spain); Soto, R.; Val, J. del; Comesaña, R.; Boutinguiza, M.; Quintero, F.; Lusquiños, F.; Pou, J. [Applied Physics Department, University of Vigo, ETSII, Lagoas-Marcosende, 9, Vigo 36310 (Spain)

2014-05-01

Ultra-high-molecular-weight polyethylene (UHMWPE) is a synthetic polymer used for biomedical applications because of its high impact resistance, ductility and stability in contact with physiological fluids. Therefore, this material is being used in human orthopedic implants such as total hip or knee replacements. Surface modification of this material relates to changes on its chemistry, microstructure, roughness, and topography, all influencing its biological response. Surface treatment of UHMWPE is very difficult due to its high melt viscosity. This work presents a systematic approach to discern the role of different laser wavelengths (λ = 1064, 532, and 355 nm) on the surface modification of carbon coated UHMWPE samples. Influence of laser processing conditions (irradiance, pulse frequency, scanning speed, and spot overlapping) on the surface properties of this material was determined using an advanced statistical planning of experiments. A full factorial design of experiments was used to find the main effects of the processing parameters. The obtained results indicate the way to maximize surface properties which largely influence cell–material interaction.

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

International Nuclear Information System (INIS)

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

1979-01-01

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

In situ high-resolution evaluation of labile arsenic and mercury in sediment of a large shallow lake

International Nuclear Information System (INIS)

Wang, Chao; Yao, Yu; Wang, Peifang; Hou, Jun; Qian, Jin; Yuan, Ye; Fan, Xiulei

2016-01-01

The precise evaluation of arsenic (As) and mercury (Hg) bioavailability in sediment is crucial to controlling As and Hg contamination, but traditional ex situ measurements hamper comprehensive analysis of labile As and Hg in sediment. In this study, we characterized in situ labile As and Hg in sediment of Lake Hongze using the zirconium (Zr) oxide diffusive gradients in thin films (DGT) technique and 3-mercaptopropyl functionalized silica gel DGT, respectively. The concentrations of DGT-labile As and Hg in the sediment profiles were found to exhibit considerable variation, ranging from 0.15 to 4.15 μg L −1 for As and from 0.04 to 1.35 μg L −1 for Hg. As and Hg flux values, calculated based on the concentration gradients measured from the DGT profiles for both the overlying water and sediment close to the sediment–water interface, were used to determine the contamination status of As and Hg. Flux values of As and Hg were between − 0.066 and 0.067 ng cm −2 d −1 and between − 0.0187 and 0.0181 ng cm −2 d −1 , respectively. The GNU's Not Unix R (GNU R) programming language was used to identify outliers of As and Hg at various depths at the sampling sites. The results indicate that the sites with the most outliers were all located in the regions that were seriously affected by contaminants from the Huai River. The DGT-labile As and Hg concentrations in the 0–30 mm layer were found to be significantly correlated with concentrations of labile As and Hg, total dissolved As and Hg, and total As and Hg in the overlying water, as indicated by ex situ measurements. Results show that DGT is a reliable and high-resolution technique that can be used for in situ monitoring of the labile fractions of As and Hg in sediment in fresh water bodies. - Graphical abstract: The principle of DGT is based on the diffusion of dissolved species through a well-defined gel and subsequent accumulation on an ion-exchange resin. A diffusion gel and a filter membrane (to

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

African Journals Online (AJOL)

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

Heat pumps; Synergy of high efficiency and low carbon electricity

Energy Technology Data Exchange (ETDEWEB)

Koike, Akio

2010-09-15

Heat pump is attracting wide attention for its high efficiency to utilize inexhaustible and renewable ambient heat in the environment. With its rapid innovation and efficiency improvement, this technology has a huge potential to reduce CO2 emissions by replacing currently widespread fossil fuel combustion systems to meet various heat demands from the residential, commercial and industrial sectors. Barriers to deployment such as low public awareness and a relatively long pay-back period do exist, so it is strongly recommended that each country implement policies to promote heat pumps as a renewable energy option and an effective method to combat global warming.

The effect of low molecular weight multifunctional additives on heavy oil viscosity

Energy Technology Data Exchange (ETDEWEB)

Oldenburg, T.B.P.; Yarranton, H.W.; Larter, S.R. [Calgary Univ., AB (Canada)

2010-07-01

Crude oils contain many small multifunctional low molecular weight components that act as linking molecules between larger functionalized species. The linkage molecules have a significant impact on the flow properties of hydrocarbon systems. This study investigated the use of a low molecular weight multiheteroatom species (LMWMH) as a molecular Velcro linking high molecular weight components together. LMWMH species were added to Albertan bitumens and heavy oil, and their impact on viscosity was investigated. Results of the experimental studies were then compared with the effects of hydrocarbon solvents on similar samples. The LMWMH species included bifunctional species and analogous alkyl and aryl monoamines that acted as blocking molecules to hinder the association of larger petroleum species. Density and viscosity measurements were conducted. A correlation method was used to predict the viscosity of the solvent-diluted heavy oil and bitumen samples. The study showed that of the tested additives, only aniline demonstrated an additional viscosity-reducing effect. The aniline inhibited asphaltene association and is a promising candidate for enhanced in-situ bitumen viscosity reduction. 23 refs., 4 tabs.

Prolonged protection against Intranasal challenge with influenza virus following systemic immunization or combinations of mucosal and systemic immunizations with a heat-labile toxin mutant.

Science.gov (United States)

Zhou, Fengmin; Goodsell, Amanda; Uematsu, Yasushi; Vajdy, Michael

2009-04-01

Seasonal influenza virus infections cause considerable morbidity and mortality in the world, and there is a serious threat of a pandemic influenza with the potential to cause millions of deaths. Therefore, practical influenza vaccines and vaccination strategies that can confer protection against intranasal infection with influenza viruses are needed. In this study, we demonstrate that using LTK63, a nontoxic mutant of the heat-labile toxin from Escherichia coli, as an adjuvant for both mucosal and systemic immunizations, systemic (intramuscular) immunization or combinations of mucosal (intranasal) and intramuscular immunizations protected mice against intranasal challenge with a lethal dose of live influenza virus at 3.5 months after the second immunization.

Effects of High Hydrostatic Pressure on Escherichia coli Ultrastructure, Membrane Integrity and Molecular Composition as Assessed by FTIR Spectroscopy and Microscopic Imaging Techniques

OpenAIRE

Prieto-Calvo, María; Prieto, Miguel; López, Mercedes; Alvarez-Ordóñez, Avelino

2014-01-01

High hydrostatic pressure (HHP) is a novel food processing technology that is considered as an attractive alternative to conventional heat treatments for the preservation of foods, due to its lethal effects on pathogenic and spoilage microorganisms, while causing minor effects on food quality and sensorial attributes. This study is aimed at investigating how HHP treatments at varying intensities in the range 50–900 MPa affect the viability, membrane integrity, ultrastructure and molecular com...

Lightweight Heat Pipes Made from Magnesium

Science.gov (United States)

Rosenfeld, John N.; Zarembo, Sergei N.; Eastman, G. Yale

2010-01-01

Magnesium has shown promise as a lighter-weight alternative to the aluminum alloys now used to make the main structural components of axially grooved heat pipes that contain ammonia as the working fluid. Magnesium heat-pipe structures can be fabricated by conventional processes that include extrusion, machining, welding, and bending. The thermal performances of magnesium heat pipes are the same as those of equal-sized aluminum heat pipes. However, by virtue of the lower mass density of magnesium, the magnesium heat pipes weigh 35 percent less. Conceived for use aboard spacecraft, magnesium heat pipes could also be attractive as heat-transfer devices in terrestrial applications in which minimization of weight is sought: examples include radio-communication equipment and laptop computers.

Molecular weight and its distribution of tetrafluoroethylene and propylene copolymer

International Nuclear Information System (INIS)

Watanabe, Hiromasa; Okamoto, Jiro; Yamaguchi, Koichi.

1978-04-01

In comparison of molecular structure of tetrafluoroethylene and propylene copolymer produced by radiation and chemical initiators respectively, both were fractionated by elution method and fine structure was examined. For the fractionated sample by radiation, the relation between molecular weight anti Mn and intrinsic viscosity ( eta] is ( eta] = 3.97 x 10 -4 anti Mnsup(0.630) The result is not in agreement with that of the unfractionated sample by radiation, and similar to those of samples by chemical initiators. There is no difference, however, in the elution method of GPC between both these copolymers; the elution behavior agrees with that of standard polystyrene. Long chain branching thus exists little in the copolymer of tetrafluoroethylene and propylene. To reveal the relations between reaction conditions and molecular weight and its distribution of the copolymer produced by flow apparatus, the molecular weight distribution was measured by GPC. The method of analysis could evaluate molecular weight distribution changing constantly. (auth.)

In vitro anticoagulation monitoring of low-molecular-weight heparin

Institute of Scientific and Technical Information of China (English)

WANG Jian-qi; SHI Xu-bo; YANG Jin-gang; HU Da-yi

2009-01-01

Background Although low-molecular-weight heparin has replaced unfractionated heparin to become the primary anticoagulation drug for treatment of acute coronary syndrome, there is no convenient bedside monitoring method. We explored the best laboratory monitoring method of low-molecular-weight heparins (enoxapadn, dalteparin, and nadroparin) by use of the Sonoclot coagulation analyzer to monitor the activated clotting time.Methods Atotal of 20 healthy volunteers were selected and 15 ml of fasting venous blood samples were collected and incubated. Four coagulants, kaolin, diatomite, glass bead, and magnetic stick, were used to determine the activated clotting time of the low-molecular-weight heparins at different in vitro anti-Xa factor concentrations. A correlation analysis was made to obtain the regression equation. The activated clotting time of the different low-molecular-weight heparins with the same anti-Xa factor concentration was monitored when the coagulant glass beads were applied. Results The activated clotting time measured using the glass beads, diatomite, kaolin, and magnetic stick showed a linear correlation with the concentration of nadroparin (r= 0.964, 0.966, 0.970, and 0.947, respectively). The regression equation showed that the linear slopes of different coagulants were significantly different (glass beads 230.03 s/IU,diatomite 89.91 s/IU, kaolin 50.87 s/IU, magnetic stick could not be calculated). When the concentration of the anti-Xa factor was the same for different low-molecular-weight heparins, the measured activated clotting time was different after the application of the glass bead coagulant.Conclusions The glass bead coagulant is most feasible for monitoring the in vitro anticoagulation activity of nadroparin.The different effects of different low-molecular-weight heparins on the activated clotting time may be related to the different anti-Ila activities.

Low molecular-weight phenols in Tannat wines made by alternative winemaking procedures.

Science.gov (United States)

Favre, Guzmán; Peña-Neira, Álvaro; Baldi, Cecilia; Hernández, Natalia; Traverso, Sofía; Gil, Graciela; González-Neves, Gustavo

2014-09-01

Low molecular weight phenols of Tannat red wines produced by Traditional Maceration (TM), Prefermentative Cold Maceration (PCM), Maceration Enzyme (ENZ) and grape-Seed Tannins additions (ST), were performed and discussed. Alternatives to TM increased wine phenolic contents but unequally, ST increased mainly smaller flavans-3-ol, PCM anthocyanins and ENZ proanthocyanidins (up to 2250 mg/L). However low molecular weight flavan-3-ols remained below 9 mg/L in all wines, showing that there is not necessarily a correspondence between wine richness in total tannins and flavan-3-ols contents at low molecular weight. PCM wines had particularly high concentrations of tyrosol and tryptophol, yeast metabolism derived compounds. The use of grape-seed enological tannins did not increase grape seed derived phenolic compounds such as gallic acid. Caftaric acid was found in concentrations much higher than those reported in other grape varieties. Wine phenolic content and composition was considerably affected by the winemaking procedures tested. Copyright © 2014 Elsevier Ltd. All rights reserved.

Molecular Theory and the Effects of Solute Attractive Forces on Hydrophobic Interactions.

Science.gov (United States)

Chaudhari, Mangesh I; Rempe, Susan B; Asthagiri, D; Tan, L; Pratt, L R

2016-03-03

The role of solute attractive forces on hydrophobic interactions is studied by coordinated development of theory and simulation results for Ar atoms in water. We present a concise derivation of the local molecular field (LMF) theory for the effects of solute attractive forces on hydrophobic interactions, a derivation that clarifies the close relation of LMF theory to the EXP approximation applied to this problem long ago. The simulation results show that change from purely repulsive atomic solute interactions to include realistic attractive interactions diminishes the strength of hydrophobic bonds. For the Ar-Ar rdfs considered pointwise, the numerical results for the effects of solute attractive forces on hydrophobic interactions are opposite in sign and larger in magnitude than predicted by LMF theory. That comparison is discussed from the point of view of quasichemical theory, and it is suggested that the first reason for this difference is the incomplete evaluation within LMF theory of the hydration energy of the Ar pair. With a recent suggestion for the system-size extrapolation of the required correlation function integrals, the Ar-Ar rdfs permit evaluation of osmotic second virial coefficients B2. Those B2's also show that incorporation of attractive interactions leads to more positive (repulsive) values. With attractive interactions in play, B2 can change from positive to negative values with increasing temperatures. This is consistent with the puzzling suggestions of decades ago that B2 ≈ 0 for intermediate cases of temperature or solute size. In all cases here, B2 becomes more attractive with increasing temperature.

SDS-PAGE analysis of high molecular weight glutenin subunits in SP3 from spaceflight carried wheat

International Nuclear Information System (INIS)

Zhang Su'na; Lv Jinyin

2009-01-01

The compositions of high molecular weight glutenin subunits (HMW-GS) of the third generation (SP 3 ) of two wheat varieties spaceflight carried were analyzed by SDS-PAGE. The quality score of Glu-1 of each site was calculated according to the quality rating system. The results showed that the space flight carried could result in a higher frequency of HMW-GS gene mutation. The variance frequency of HMW-GS in SP 3 of Shaan253 and Xinong1043 were 27.08% and 27.45%, and the quality score in SP 3 of Shaan253 and Xinong1043 were 7 and 6, respectively. Shaan253 SP 3 generation mutants were considered as high-quality wheat. (authors)

Ubiquitous water-soluble molecules in aquatic plant exudates determine specific insect attraction.

Science.gov (United States)

Sérandour, Julien; Reynaud, Stéphane; Willison, John; Patouraux, Joëlle; Gaude, Thierry; Ravanel, Patrick; Lempérière, Guy; Raveton, Muriel

2008-10-08

Plants produce semio-chemicals that directly influence insect attraction and/or repulsion. Generally, this attraction is closely associated with herbivory and has been studied mainly under atmospheric conditions. On the other hand, the relationship between aquatic plants and insects has been little studied. To determine whether the roots of aquatic macrophytes release attractive chemical mixtures into the water, we studied the behaviour of mosquito larvae using olfactory experiments with root exudates. After testing the attraction on Culex and Aedes mosquito larvae, we chose to work with Coquillettidia species, which have a complex behaviour in nature and need to be attached to plant roots in order to obtain oxygen. This relationship is non-destructive and can be described as commensal behaviour. Commonly found compounds seemed to be involved in insect attraction since root exudates from different plants were all attractive. Moreover, chemical analysis allowed us to identify a certain number of commonly found, highly water-soluble, low-molecular-weight compounds, several of which (glycerol, uracil, thymine, uridine, thymidine) were able to induce attraction when tested individually but at concentrations substantially higher than those found in nature. However, our principal findings demonstrated that these compounds appeared to act synergistically, since a mixture of these five compounds attracted larvae at natural concentrations (0.7 nM glycerol, insect relationships in aquatic eco-systems.

Biodegradation of low and high molecular weight hydrocarbons in petroleum refinery wastewater by a thermophilic bacterial consortium.

Science.gov (United States)

Pugazhendi, Arulazhagan; Abbad Wazin, Hadeel; Qari, Huda; Basahi, Jalal Mohammad Al-Badry; Godon, Jean Jacques; Dhavamani, Jeyakumar

2017-10-01

Clean-up of contaminated wastewater remains to be a major challenge in petroleum refinery. Here, we describe the capacity of a bacterial consortium enriched from crude oil drilling site in Al-Khobar, Saudi Arabia, to utilize polycyclic aromatic hydrocarbons (PAHs) as sole carbon source at 60°C. The consortium reduced low molecular weight (LMW; naphthalene, phenanthrene, fluorene and anthracene) and high molecular weight (HMW; pyrene, benzo(e)pyrene and benzo(k)fluoranthene) PAH loads of up to 1.5 g/L with removal efficiencies of 90% and 80% within 10 days. PAH biodegradation was verified by the presence of PAH metabolites and evolution of carbon dioxide (90 ± 3%). Biodegradation led to a reduction of the surface tension to 34 ± 1 mN/m thus suggesting biosurfactant production by the consortium. Phylogenetic analysis of the consortium revealed the presence of the thermophilic PAH degrader Pseudomonas aeruginosa strain CEES1 (KU664514) and Bacillus thermosaudia (KU664515) strain CEES2. The consortium was further found to treat petroleum wastewater in continuous stirred tank reactor with 96 ± 2% chemical oxygen demand removal and complete PAH degradation in 24 days.

An evaluation of the effects of PEO/PEG molecular weights on extruded alumina rods

Science.gov (United States)

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 influence of molecular weight in radiotracers of inflamators processes

International Nuclear Information System (INIS)

Mesa Duennas, N.; Zayas Crespo, F.; Piedra Mazorra, J.; Diaz Barreto, M; Rodriguez Alfonso, M.E.; Perez Fuentes, A.

2004-01-01

Four 99mTc-radiopharmaceuticals (RPs) were compared as a radiotracers of inflammatory process. The RPs were divided in two groups according to their molecular weights and nature. One group included the human IgG and the ior t3 MoAb (anti-CD3), another included the Ciprofloxacine and the DMSA. The RPs were studied by different quality controls, and a biodistribution study in an aseptic inflammatory model made by steril Carragenin. The results obtained in the reduction of the immunoglobulins with 2-mercaptoethanol and sodium metabisulphite demonstrated that both reducing agents were equivalent, because the radiochemical purity obtained were similar and independent of the immunoglobulins. The biodistribution demonstrated a higher incorporation for the radiopharmaceuticals of high molecular weight, and the highest values were obtained with the 2-mercaptoethanol

In situ high-resolution evaluation of labile arsenic and mercury in sediment of a large shallow lake

Energy Technology Data Exchange (ETDEWEB)

Wang, Chao; Yao, Yu; Wang, Peifang; Hou, Jun; Qian, Jin; Yuan, Ye; Fan, Xiulei

2016-01-15

The precise evaluation of arsenic (As) and mercury (Hg) bioavailability in sediment is crucial to controlling As and Hg contamination, but traditional ex situ measurements hamper comprehensive analysis of labile As and Hg in sediment. In this study, we characterized in situ labile As and Hg in sediment of Lake Hongze using the zirconium (Zr) oxide diffusive gradients in thin films (DGT) technique and 3-mercaptopropyl functionalized silica gel DGT, respectively. The concentrations of DGT-labile As and Hg in the sediment profiles were found to exhibit considerable variation, ranging from 0.15 to 4.15 μg L{sup −1} for As and from 0.04 to 1.35 μg L{sup −1} for Hg. As and Hg flux values, calculated based on the concentration gradients measured from the DGT profiles for both the overlying water and sediment close to the sediment–water interface, were used to determine the contamination status of As and Hg. Flux values of As and Hg were between − 0.066 and 0.067 ng cm{sup −2} d{sup −1} and between − 0.0187 and 0.0181 ng cm{sup −2} d{sup −1}, respectively. The GNU's Not Unix R (GNU R) programming language was used to identify outliers of As and Hg at various depths at the sampling sites. The results indicate that the sites with the most outliers were all located in the regions that were seriously affected by contaminants from the Huai River. The DGT-labile As and Hg concentrations in the 0–30 mm layer were found to be significantly correlated with concentrations of labile As and Hg, total dissolved As and Hg, and total As and Hg in the overlying water, as indicated by ex situ measurements. Results show that DGT is a reliable and high-resolution technique that can be used for in situ monitoring of the labile fractions of As and Hg in sediment in fresh water bodies. - Graphical abstract: The principle of DGT is based on the diffusion of dissolved species through a well-defined gel and subsequent accumulation on an ion-exchange resin. A diffusion

Radiodegradation process in PVDF with different molecular weight

International Nuclear Information System (INIS)

Silva, L.; Batista, A.S.M.; Nascimento, J.P.; Furtado, C.A.; Faria, L.O.

2017-01-01

Poly(vinylidene fluoride) (PVDF) is a semi-crystalline polymer with several industrial applications due to its mechanical, ferroelectric and biocompatibility properties. Due to the particularity of some of its applications this polymer is exposed to high energy radiation, for example in the aerospace industry and with biomaterial, in sterilization processes. In this sense it is of interest studies that evaluate the radiodegradation of this material, as a way to predict its mechanical behavior after processes of exposure to gamma radiation. In this study the radioresistance of PVDF with different molecular weights is evaluated, considering that large molecular chains can provide greater resistance than smaller chains. Method: PVDF samples with different molecular weights were produced by the solvent dilution process. They were irradiated with gamma doses of 100, 300, 500, 1000 and 2000 kGy with a source of cobalt in the Laboratório de Irradiação Gama (LIG) of the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN). FTIR, UV-Vis, DSC and XRD analyzes were used to evaluate the induced radiodegradation processes immediately after irradiation and one month later. Results: The FTIR and UV-Vis analyzes showed formation of unsaturations in the polymer chains. The DSC technique showed a drop in the crystalline fraction of the polymer confirmed by the XRD technique. Conclusion: Post-irradiation sample evaluations are discussed in terms of the effect of high energy ionizing radiation on polymeric mate-rials for industrial and biomedical use for safety in quality assurance and performance in service. (author)

Radiodegradation process in PVDF with different molecular weight

Energy Technology Data Exchange (ETDEWEB)

Silva, L.; Batista, A.S.M., E-mail: adriananuclear@yahoo.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Nascimento, J.P.; Furtado, C.A.; Faria, L.O. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2017-07-01

Poly(vinylidene fluoride) (PVDF) is a semi-crystalline polymer with several industrial applications due to its mechanical, ferroelectric and biocompatibility properties. Due to the particularity of some of its applications this polymer is exposed to high energy radiation, for example in the aerospace industry and with biomaterial, in sterilization processes. In this sense it is of interest studies that evaluate the radiodegradation of this material, as a way to predict its mechanical behavior after processes of exposure to gamma radiation. In this study the radioresistance of PVDF with different molecular weights is evaluated, considering that large molecular chains can provide greater resistance than smaller chains. Method: PVDF samples with different molecular weights were produced by the solvent dilution process. They were irradiated with gamma doses of 100, 300, 500, 1000 and 2000 kGy with a source of cobalt in the Laboratório de Irradiação Gama (LIG) of the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN). FTIR, UV-Vis, DSC and XRD analyzes were used to evaluate the induced radiodegradation processes immediately after irradiation and one month later. Results: The FTIR and UV-Vis analyzes showed formation of unsaturations in the polymer chains. The DSC technique showed a drop in the crystalline fraction of the polymer confirmed by the XRD technique. Conclusion: Post-irradiation sample evaluations are discussed in terms of the effect of high energy ionizing radiation on polymeric mate-rials for industrial and biomedical use for safety in quality assurance and performance in service. (author)

Structure characterization of the central repetitive domain of high molecular weight gluten proteins .1. Model studies using cyclic and linear peptides

NARCIS (Netherlands)

VanDijk, AA; VanWijk, LL; VanVliet, A; Haris, P; VanSwieten, E; Tesser, GI; Robillard, GT

The high molecular weight (HMW) proteins from wheat contain a repetitive domain that forms 60-80% of their sequence. The consensus peptides PGQGQQ and GYYPTSPQQ form more than 90% of the domain; both are predicted to adopt beta-turn structure. This paper describes the structural characterization of

Influence of molecular weight on the fracture properties of aliphatic polyketone terpolymers

NARCIS (Netherlands)

Zuiderduin, W.C.J.; Homminga, D.S.; Homminga, D.S.; Huetink, Han; Gaymans, R.J.

2003-01-01

The influence of polymer molecular weight on the mechanical properties of aliphatic polyketones was investigated. The molecular weight varied from 100,000 to 300,000 g mol21. The crystallinity was found to be independent of polymer molecular weight, as was the glass transition temperature. The yield

Mechanochemical Ring-Opening Polymerization of Lactide: Liquid-Assisted Grinding for the Green Synthesis of Poly(lactic acid) with High Molecular Weight.

Science.gov (United States)

Ohn, Nuri; Shin, Jihoon; Kim, Sung Sik; Kim, Jeung Gon

2017-09-22

Mechanochemical polymerization of lactide is carried out by using ball milling. Mechanical energy from collisions between the balls and the vessel efficiently promotes an organic-base-mediated metal- and solvent-free solid-state polymerization. Investigation of the parameters of the ball-milling synthesis revealed that the degree of lactide ring-opening polymerization could be modulated by the ball-milling time, vibration frequency, mass of the ball media, and liquid-assisted grinding. Liquid-assisted grinding was found to be an especially important factor for achieving a high degree of mechanochemical polymerization. Although polymer-chain scission from the strong collision energy prevented mechanical-force-driven high-molecular-weight polymer synthesis, the addition of only a small amount of liquid enabled sufficient energy dissipation and poly(lactic acid) was thereby obtained with a molecular weight of over 1×10 5  g mol -1 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interactions among Carbon Dioxide, Heat, and Chemical Lures in Attracting the Bed Bug, Cimex lectularius L. (Hemiptera: Cimicidae

Directory of Open Access Journals (Sweden)

Narinderpal Singh

2012-01-01

Full Text Available Commercial bed bug (Cimex lectularius L. monitors incorporating carbon dioxide (CO2, heat, and chemical lures are being used for detecting bed bugs; however, there are few reported studies on the effectiveness of chemical lures in bed bug monitors and the interactions among chemical lure, CO2, and heat. We screened 12 chemicals for their attraction to bed bugs and evaluated interactions among chemical lures, CO2, and heat. The chemical lure mixture consisting of nonanal, 1-octen-3-ol, spearmint oil, and coriander Egyptian oil was found to be most attractive to bed bugs and significantly increased the trap catches in laboratory bioassays. Adding this chemical lure mixture when CO2 was present increased the trap catches compared with traps baited with CO2 alone, whereas adding heat did not significantly increase trap catches when CO2 was present. Results suggest a combination of chemical lure and CO2 is essential for designing effective bed bug monitors.

Transparent Heat-Resistant PMMA Copolymers for Packing Light-Emitting Diode Materials

Directory of Open Access Journals (Sweden)

Shu-Ling Yeh

2015-07-01

Full Text Available Transparent and heat-resistant poly(methyl methacrylate copolymers were synthesized by bulk polymerizing methyl methacrylate (MMA, isobornyl methacrylate (IBMA, and methacrylamide (MAA monomers. Copolymerization was performed using a chain transfer agent to investigate the molecular weight changes of these copolymers, which exhibited advantages including a low molecular weight distribution, excellent optical properties, high transparency, high glass transition temperature, low moisture absorption, and pellets that can be readily mass produced by using extrusion or jet injection for packing light-emitting diode materials.

Molecular weight characterisation of synthetic polymers

CERN Document Server

Holding, Steve R

1995-01-01

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

The polysaccharide and low molecular weight components of Opuntia ficus indica cladodes: Structure and skin repairing properties.

Science.gov (United States)

Di Lorenzo, Flaviana; Silipo, Alba; Molinaro, Antonio; Parrilli, Michelangelo; Schiraldi, Chiara; D'Agostino, Antonella; Izzo, Elisabetta; Rizza, Luisa; Bonina, Andrea; Bonina, Francesco; Lanzetta, Rosa

2017-02-10

The Opuntia ficus-indica multiple properties are reflected in the increasing interest of chemists in the identification of its natural components having pharmaceutical and/or cosmetical applications. Here we report the structural elucidation of Opuntia ficus-indica mucilage that highlighted the presence of components differing for their chemical nature and the molecular weight distribution. The high molecular weight components were identified as a linear galactan polymer and a highly branched xyloarabinan. The low molecular weight components were identified as lactic acid, D-mannitol, piscidic, eucomic and 2-hydroxy-4-(4'-hydroxyphenyl)-butanoic acids. A wound healing assay was performed in order to test the cicatrizing properties of the various components, highlighting the ability of these latter to fasten dermal regeneration using a simplified in vitro cellular model based on a scratched keratinocytes monolayer. The results showed that the whole Opuntia mucilage and the low molecular weight components are active in the wound repair. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rheological Link Between Polymer Melts with a High Molecular Weight Tail and Enhanced Formation of Shish-Kebabs

DEFF Research Database (Denmark)

Wingstrand, Sara Lindeblad; Shen, Bo; Kornfield, Julie A.

2017-01-01

Presence of an ultra high molecular weight (UHMw) fraction in flowingpolymer melts is known to facilitate formation of oriented crystalline structures significantly. The UHMw fraction manifests itself as a minor tail in the molar mass distribution and is hardly detectable in the canonical...... a clear increase in extensional stress that is directly correlated with the crystalline orientation of the quenched samples. Extensional rheology, particularly, in combination with linear creep measurements, thus, enables the conformational evolution of the UHMw-tail to be studied and linked...

Hypoglycemic effect of polysaccharides with different molecular weight of Pseudostellaria heterophylla

Science.gov (United States)

2013-01-01

Abstracts Background The aims of this study were to evaluate the antidiabetic activity and to detect molecular size of Pseudostellaria heterophylla polysaccharide (PHP). Pseudostellaria heterophylla is a medicine extensively used in traditional Chinese medicine formulas to treat diabetes and its complications. Methods Molecular weight of PHP was determined by gel permeation chromatography combined with phenol-sulphuric acid method and the monosaccharides composition was determined by HPLC with a precolumn derivatization. Four polysaccharides with different molecular weight were compared for hypoglycemic active on two animal models both high does alloxan induced type1 diabetic mellitus (T1DM) and high-fat/lower does streptozotocin induced type2 diabetic mellitus (T2DM). Blood sugar, glucose tolerance, and insulin tolerance were detected. Rat serum IL-1β, IL-2, IL-10, Leptin, TNF-α, Acrp30 and CRP were also analyzed by sandwich-ELISA approaches to preliminary probe the hypoglycemic mechanism of PHP. Results The hypoglycemic effects related to molecular size of polysaccharide were more effective against T2DM than T1DM. PHP comprise four monosaccharides of galacturonic acid, glucose, galactose and arabinos. T2DM rats daily receiving oral dose of polysaccharide(100 ~ 400 mg/kg) with 50 ~ 210 kDa molecular weight (PF40) could not only significantly lower blood sugar but also reduce total triglyceride level in serum. PF40 improves in insulin tolerance inhibited the expression of some biomarkers including inflammatory cytokine TNF-α and elevated anti-inflammatory cytokine IL-10, regulated adiponectin Acrp30 and leptin. Conclusions PF40 prevent the cascade of inflammatory events in the treatment of T2DM to block overweight progresses to obesity. PMID:24131482

Determination of the Temperature Dependence of Heat Capacity for Some Molecular Crystals of Nitro Compounds

Science.gov (United States)

Kovalev, Yu. M.; Kuropatenko, V. F.

2018-05-01

An analysis of the existing approximations used for describing the dependence of heat capacity at a constant volume on the temperature of a molecular crystal has been carried out. It is shown that the considered Debye and Einstein approximations do not enable one to adequately describe the dependence of heat capacity at a constant volume on the temperature of the molecular crystals of nitro compounds. This inference requires the development of special approximations that would describe both low-frequency and high-frequency parts of the vibrational spectra of molecular crystals. This work presents a universal dependence allowing one to describe the dependence of heat capacity at a constant volume on temperature for a number of molecular crystals of nitro compounds.

Purification of High Molecular Weight Genomic DNA from Powdery Mildew for Long-Read Sequencing.

Science.gov (United States)

Feehan, Joanna M; Scheibel, Katherine E; Bourras, Salim; Underwood, William; Keller, Beat; Somerville, Shauna C

2017-03-31

The powdery mildew fungi are a group of economically important fungal plant pathogens. Relatively little is known about the molecular biology and genetics of these pathogens, in part due to a lack of well-developed genetic and genomic resources. These organisms have large, repetitive genomes, which have made genome sequencing and assembly prohibitively difficult. Here, we describe methods for the collection, extraction, purification and quality control assessment of high molecular weight genomic DNA from one powdery mildew species, Golovinomyces cichoracearum. The protocol described includes mechanical disruption of spores followed by an optimized phenol/chloroform genomic DNA extraction. A typical yield was 7 µg DNA per 150 mg conidia. The genomic DNA that is isolated using this procedure is suitable for long-read sequencing (i.e., > 48.5 kbp). Quality control measures to ensure the size, yield, and purity of the genomic DNA are also described in this method. Sequencing of the genomic DNA of the quality described here will allow for the assembly and comparison of multiple powdery mildew genomes, which in turn will lead to a better understanding and improved control of this agricultural pathogen.

molecular weight control of a batch suspension polymerization reactor

International Nuclear Information System (INIS)

Shahrokhi, M.; Fanaei, M. A.

2002-01-01

This paper concerns molecular weight control of a batch polymerization reactor where suspension polymerization of methyl methylacrylate (MMA) takes place. For this purpose, a cascade control structure with two control loops has been selected. The slave loop is used for temperature control using on-line temperature measurements, and the master loop controls the average molecular weights based on its estimated values. Two different control algorithms namely proportional-integral (PI) controller and globally linearizing controller (GLC) have been used for temperature control. An estimator, which has the structure of an extended Kalman filter(EKF), is used for estimating monomer conversion and average molecular weights of polymer using reactor temperature measurements. The performance of proposed control algorithm is evaluated through simulation and experimental studies. The results indicate that a constant average molecular weight cannot be achieved in case of strong gel effect. However, the polydispersity of product will be lower in comparison to isothermal operation. It is also shown that in case of mo dek mismatch, the performance of cascade control is superior compared to the case where only reactor temperature is controlled based on desired temperature trajectory obtained through cascade strategy

Exploration of High Harmonic Fast Wave Heating on the National Spherical Torus Experiment

International Nuclear Information System (INIS)

Wilson, J.R.; Bell, R.E.; Bernabei, S.; Bitter, M.; Bonoli, P.; Gates, D.; Hosea, J.; LeBlanc, B.; Mau, T.K.; Medley, S.; Menard, J.; Mueller, D.; Ono, M.; Phillips, C.K.; Pinsker, R.I.; Raman, R.; Rosenberg, A.; Ryan, P.; Sabbagh, S.; Stutman, D.; Swain, D.; Takase, Y.; Wilgen, J.

2003-01-01

High Harmonic Fast Wave (HHFW) heating has been proposed as a particularly attractive means for plasma heating and current drive in the high-beta plasmas that are achievable in spherical torus (ST) devices. The National Spherical Torus Experiment (NSTX) [Ono, M., Kaye, S.M., Neumeyer, S., et al., Proceedings, 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque, 1999, (IEEE, Piscataway, NJ (1999), p. 53.)] is such a device. An radio-frequency (rf) heating system has been installed on NSTX to explore the physics of HHFW heating, current drive via rf waves and for use as a tool to demonstrate the attractiveness of the ST concept as a fusion device. To date, experiments have demonstrated many of the theoretical predictions for HHFW. In particular, strong wave absorption on electrons over a wide range of plasma parameters and wave parallel phase velocities, wave acceleration of energetic ions, and indications of current drive for directed wave spectra have been observed. In addition HHFW heating has been used to explore the energy transport properties of NSTX plasmas, to create H-mode (high-confinement mode) discharges with a large fraction of bootstrap current and to control the plasma current profile during the early stages of the discharge

Identification of unprecedented anticancer properties of high molecular weight biomacromolecular complex containing bovine lactoferrin (HMW-bLf.

Directory of Open Access Journals (Sweden)

Fawzi Ebrahim

Full Text Available With the successful clinical trials, multifunctional glycoprotein bovine lactoferrin is gaining attention as a safe nutraceutical and biologic drug targeting cancer, chronic-inflammatory, viral and microbial diseases. Interestingly, recent findings that human lactoferrin oligomerizes under simulated physiological conditions signify the possible role of oligomerization in the multifunctional activities of lactoferrin molecule during infections and in disease targeting signaling pathways. Here we report the purification and physicochemical characterization of high molecular weight biomacromolecular complex containing bovine lactoferrin (≥250 kDa, from bovine colostrum, a naturally enriched source of lactoferrin. It showed structural similarities to native monomeric iron free (Apo lactoferrin (∼78-80 kDa, retained anti-bovine lactoferrin antibody specific binding and displayed potential receptor binding properties when tested for cellular internalization. It further displayed higher thermal stability and better resistance to gut enzyme digestion than native bLf monomer. High molecular weight bovine lactoferrin was functionally bioactive and inhibited significantly the cell proliferation (p<0.01 of human breast and colon carcinoma derived cells. It induced significantly higher cancer cell death (apoptosis and cytotoxicity in a dose-dependent manner in cancer cells than the normal intestinal cells. Upon cellular internalization, it led to the up-regulation of caspase-3 expression and degradation of actin. In order to identify the cutting edge future potential of this bio-macromolecule in medicine over the monomer, its in-depth structural and functional properties need to be investigated further.

Extra Heat Loss Through Light Weight Roofs Due to Latent Heat

DEFF Research Database (Denmark)

Rode, Carsten

1996-01-01

that changes phase at the terminals of its passage.Note however, that convection of air most often will have an important effect on the overall heat flow - but that is a different topic.Macroscopic latent heat transferConsider the following scenario: Initially, moisture is present in its condensed or frozen......This report is one in a series of papers in Task 5 of IEA Annex 24 on how moisture and air movements affect the energy performance of building constructions. The effect of latent heat flow will be demonstrated by means of an example: a light weight flat roof.Latent heat flow is one of three...... processes by which moisture affects energy performance:Higher thermal conductivityMoist materials have higher thermal con-ductivity than when they are dry. This is because thermally conducting moisture replaces the better insulating air in the pores of the materials. Moisture also enhan-ces the thermal...

Communication: High pressure specific heat spectroscopy reveals simple relaxation behavior of glass forming molecular liquid

DEFF Research Database (Denmark)

Roed, Lisa Anita; Niss, Kristine; Jakobsen, Bo

2015-01-01

The frequency dependent specific heat has been measured under pressure for the molecular glass forming liquid 5-polyphenyl-4-ether in the viscous regime close to the glass transition. The temperature and pressure dependences of the characteristic time scale associated with the specific heat...... is compared to the equivalent time scale from dielectric spectroscopy performed under identical conditions. It is shown that the ratio between the two time scales is independent of both temperature and pressure. This observation is non-trivial and demonstrates the existence of specially simple molecular...... liquids in which different physical relaxation processes are both as function of temperature and pressure/density governed by the same underlying “inner clock.” Furthermore, the results are discussed in terms of the recent conjecture that van der Waals liquids, like the measuredliquid, comply...

High Molecular Weight Forms of Mammalian Respiratory Chain Complex II

Czech Academy of Sciences Publication Activity Database

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

2013-01-01

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

Protein Molecular Structures, Protein SubFractions, and Protein Availability Affected by Heat Processing: A Review

International Nuclear Information System (INIS)

Yu, P.

2007-01-01

The utilization and availability of protein depended on the types of protein and their specific susceptibility to enzymatic hydrolysis (inhibitory activities) in the gastrointestine and was highly associated with protein molecular structures. Studying internal protein structure and protein subfraction profiles leaded to an understanding of the components that make up a whole protein. An understanding of the molecular structure of the whole protein was often vital to understanding its digestive behavior and nutritive value in animals. In this review, recently obtained information on protein molecular structural effects of heat processing was reviewed, in relation to protein characteristics affecting digestive behavior and nutrient utilization and availability. The emphasis of this review was on (1) using the newly advanced synchrotron technology (S-FTIR) as a novel approach to reveal protein molecular chemistry affected by heat processing within intact plant tissues; (2) revealing the effects of heat processing on the profile changes of protein subfractions associated with digestive behaviors and kinetics manipulated by heat processing; (3) prediction of the changes of protein availability and supply after heat processing, using the advanced DVE/OEB and NRC-2001 models, and (4) obtaining information on optimal processing conditions of protein as intestinal protein source to achieve target values for potential high net absorbable protein in the small intestine. The information described in this article may give better insight in the mechanisms involved and the intrinsic protein molecular structural changes occurring upon processing.

A QTL on the short arm of wheat (Triticum aestivum L.) chromosome 3B affects the stability of grain weight in plants exposed to a brief heat shock early in grain filling.

Science.gov (United States)

Shirdelmoghanloo, Hamid; Taylor, Julian D; Lohraseb, Iman; Rabie, Huwaida; Brien, Chris; Timmins, Andy; Martin, Peter; Mather, Diane E; Emebiri, Livinus; Collins, Nicholas C

2016-04-22

Molecular markers and knowledge of traits associated with heat tolerance are likely to provide breeders with a more efficient means of selecting wheat varieties able to maintain grain size after heat waves during early grain filling. A population of 144 doubled haploids derived from a cross between the Australian wheat varieties Drysdale and Waagan was mapped using the wheat Illumina iSelect 9,000 feature single nucleotide polymorphism marker array and used to detect quantitative trait loci for heat tolerance of final single grain weight and related traits. Plants were subjected to a 3 d heat treatment (37 °C/27 °C day/night) in a growth chamber at 10 d after anthesis and trait responses calculated by comparison to untreated control plants. A locus for single grain weight stability was detected on the short arm of chromosome 3B in both winter- and autumn-sown experiments, determining up to 2.5 mg difference in heat-induced single grain weight loss. In one of the experiments, a locus with a weaker effect on grain weight stability was detected on chromosome 6B. Among the traits measured, the rate of flag leaf chlorophyll loss over the course of the heat treatment and reduction in shoot weight due to heat were indicators of loci with significant grain weight tolerance effects, with alleles for grain weight stability also conferring stability of chlorophyll ('stay-green') and shoot weight. Chlorophyll loss during the treatment, requiring only two non-destructive readings to be taken, directly before and after a heat event, may prove convenient for identifying heat tolerant germplasm. These results were consistent with grain filling being limited by assimilate supply from the heat-damaged photosynthetic apparatus, or alternatively, accelerated maturation in the grains that was correlated with leaf senescence responses merely due to common genetic control of senescence responses in the two organs. There was no evidence for a role of mobilized stem reserves (water

Angioplastic necrolytic migratory erythema. Unique association of necrolytic migratory erythema, extensive angioplasia, and high molecular weight glucagon-like polypeptide

International Nuclear Information System (INIS)

Franchimont, C.; Pierard, G.E.; Luyckx, A.S.; Gerard, J.; Lapiere, C.M.

1982-01-01

A diabetic patient developed necrolytic migratory erythema with extensive angioplasia and high molecular weight glucagon-like polypeptide. There was no associated neoplasm such as glucagonoma. Lesions in the skin were studied by standard optical microscopy and by radioautography after incorporation of tritiated thymidine. Alterations in the skin begin as focal necrosis in the epidermis and in epithelial structures of adnexa, followed by marked angioplasia and a superficial and deep perivascular dermatitis

Solubility of crystalline organic compounds in high and low molecular weight amorphous matrices above and below the glass transition by zero enthalpy extrapolation.

Science.gov (United States)

Amharar, Youness; Curtin, Vincent; Gallagher, Kieran H; Healy, Anne Marie

2014-09-10

Pharmaceutical applications which require knowledge of the solubility of a crystalline compound in an amorphous matrix are abundant in the literature. Several methods that allow the determination of such data have been reported, but so far have only been applicable to amorphous polymers above the glass transition of the resulting composites. The current work presents, for the first time, a reliable method for the determination of the solubility of crystalline pharmaceutical compounds in high and low molecular weight amorphous matrices at the glass transition and at room temperature (i.e. below the glass transition temperature), respectively. The solubilities of mannitol and indomethacin in polyvinyl pyrrolidone (PVP) K15 and PVP K25, respectively were measured at different temperatures. Mixtures of undissolved crystalline solute and saturated amorphous phase were obtained by annealing at a given temperature. The solubility at this temperature was then obtained by measuring the melting enthalpy of the crystalline phase, plotting it as a function of composition and extrapolating to zero enthalpy. This new method yielded results in accordance with the predictions reported in the literature. The method was also adapted for the measurement of the solubility of crystalline low molecular weight excipients in amorphous active pharmaceutical ingredients (APIs). The solubility of mannitol, glutaric acid and adipic acid in both indomethacin and sulfadimidine was experimentally determined and successfully compared with the difference between their respective calculated Hildebrand solubility parameters. As expected from the calculations, the dicarboxylic acids exhibited a high solubility in both amorphous indomethacin and sulfadimidine, whereas mannitol was almost insoluble in the same amorphous phases at room temperature. This work constitutes the first report of the methodology for determining an experimentally measured solubility for a low molecular weight crystalline solute

Transdermal delivery of relatively high molecular weight drugs using novel self-dissolving microneedle arrays fabricated from hyaluronic acid and their characteristics and safety after application to the skin.

Science.gov (United States)

Liu, Shu; Jin, Mei-na; Quan, Ying-shu; Kamiyama, Fumio; Kusamori, Kosuke; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

2014-02-01

The purpose of this study was to develop novel dissolving microneedle arrays fabricated from hyaluronic acid (HA) as a material and to improve the transdermal permeability of relatively high molecular weight drugs. In this study, fluorescein isothiocyanate-labeled dextran with an average molecular weight of 4kDa (FD4) was used as a model drug with a relatively high molecular weight. The microneedle arrays significantly increased transepidermal water loss (TEWL) and reduced transcutaneous electrical resistance (TER), indicating that they could puncture the skin and create drug permeation pathways successfully. Both TEWL and TER almost recovered to baseline levels in the microneedle array group, and relatively small pathways created by the microneedles rapidly recovered as compared with those created by a tape stripping treatment. These findings confirmed that the microneedle arrays were quite safe. Furthermore, we found that the transdermal permeability of FD4 using the microneedle arrays was much higher than that of the FD4 solution. Furthermore, we found that the microneedle arrays were much more effective for increasing the amount of FD4 accumulated in the skin. These findings indicated that using novel microneedle arrays fabricated from HA is a very useful and effective strategy to improve the transdermal delivery of drugs, especially relatively high molecular weight drugs without seriously damaging the skin. Copyright © 2013 Elsevier B.V. All rights reserved.

Effects of Post-Anthesis Drought and Waterlogging on Accumulation of High-Molecular-Weight Glutenin Subunits and Glutenin Macropolymers Content in Wheat Grain

DEFF Research Database (Denmark)

Jiang, D; Yue, H; Wollenweber, B

2009-01-01

Drought and flooding during grain filling have become major constraints to wheat quality and yield. The impacts of water deficits and waterlogging during the grain filling on contents of high-molecular-weight glutenin subunits (HMW-GS) and of glutenin macropolymers (GMP) in grains of the winter w...

The effect of chromic acid treatment on the mechanical and tribological properties of aramid fibre reinforced ultra-high molecular weight polyethylene composite

NARCIS (Netherlands)

Hofste, JM; Pennings, AJ; Schut, J.A.

1998-01-01

Surface oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder has an influence on the mixing procedure of chopped fibres and UHMWPE powder. Due to this oxidation hydrogen bonds can be formed between the fibres and powder particles, leading to a more homogeneous fibre-powder mixture.

The role of microbial low-molecular-weight autoregulatory factors (alkylhydroxybenzenes) in resistance of microorganisms to radiation and heat shock

Science.gov (United States)

El-Registan, Galina I.; Mulyukin, Andrey L.; Nikolaev, Yuri A.; Stepanenko, Irina Yu.; Kozlova, Alla N.; Martirosova, Elena I.; Shanenko, Elena F.; Strakhovskaya, Marina G.; Revina, Aleksandra A.

Low-molecular-weight cell-to-cell communication factors are produced by various pro- and eukaryotes and involved in autoregulation of the growth and development of microbial cultures. As for some bacterial and yeast species, these factors were identified as isomers and homologues of alkylhydroxybenzenes (AHB). Depending on the concentration, they participate in controlling the transition to stationary phase, entering the resting state, and stress resistance of vegetative cells to gamma-irradiation, photooxidation (singlet oxygen), and heat shock. Chemical analogues of microbial AHB protected microbial cultures from stressful situations and exerted (1) the stabilizing activity toward macromolecules and (2) the ability to scavenge active oxygen species. The stabilizing effect of AHBs resulted from their complex formation with protected macromolecules due to intermolecular hydrogen bonds, hydrophobic and electrostatic interactions and was demonstrated on models of individual enzymes (trypsin). Particularly, AHBs protected the yeast from the action of (a) active oxygen species formed during gamma-irradiation (500 Gy, 1.96 Gy/s) or (b) singlet oxygen generated in cells photosensitized by chlorin e 6 (10 μg/L). It is important that microbial AHBs were not species-specific and defended cultured microbial and animal cells from the action of organic toxicants. The use of AHBs as protectants and adaptogens is discussed as well as perspectives of further investigations.

Effect of molecular weight on the quality of poly(alpha-methylstyrene mandrel

Directory of Open Access Journals (Sweden)

Xiuyun Shangguan

2017-07-01

Full Text Available Hollow poly(alpha-methylstyrene (PAMS shows application in inertial confinement fusion experiments as the degradable mandrels of glow plasma polymer shells. However, the molecular weight of PAMS has great influence on the quality of mandrels. In this work, this influence was systematically studied using several PAMS samples with different molecular weights. For PAMS shells with 900 μm inner diameter and different wall thickness, when the molecular weight of PAMS is in the range of 300–500 kg·mol−1, perfect sphericity and good wall thickness uniformity can be obtained. In contrast, when increasing molecular weight to 800 kg·mol−1, the sphericity and the wall thickness uniformity become worse. Moreover, compared with the wall uniformity, the sphericity of PAMS shells was much less sensitive to the molecular weight. The results also showed that the stability of W1/O compound droplets of PAMS shells were less affected by the molecular weight. It was revealed that the wall uniformity and the sphericity of the PAMS shells were associated with the diffusion rates of fluorobenzene (FB.

Kinetics of low temperature polyester dyeing with high molecular weight disperse dyes by solvent microemulsion and agrosourced auxiliaries

OpenAIRE

Radei, Shahram; Carrión-Fité, Francisco Javier; Ardanuy Raso, Mònica; Canal Arias, José Ma

2018-01-01

This work focused on the evaluation of the kinetics of dyeing polyester fabrics with high molecular weight disperse dyes, at low temperature by solvent microemulsion. This study also compared the effect of two non-toxic agro-sourced auxiliaries (o-vanillin and coumarin) using a non-toxic organic solvent. A dyeing bath consisting of a micro-emulsion system involving a small proportion of n-butyl acetate was used, and the kinetics of dyeing were analysed at four temperatures (83, 90, 95 and 100...

Hydrodynamic characterization and molecular weight estimation of ultrasonically sheared DNA

International Nuclear Information System (INIS)

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

1981-01-01

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

Hydrodynamic caracterization and molecular weight stimation of ultrasonically sheared DNA

International Nuclear Information System (INIS)

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

1981-01-01

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

Effect of incentives on the financial attractiveness of solar industrial process heating in India★

Directory of Open Access Journals (Sweden)

Sharma Ashish K.

2017-01-01

Full Text Available India has a huge industrial demand for process heating at temperatures that can be provided with commercially available solar collectors. Government of India with support from multi-lateral agencies has initiated an ambitious programme for promoting large scale adoption of Solar Industrial Process Heating (SIPH in the industrial sector of the country. This paper presents the details of an attempt to study the effect of several existing and potential incentives on the financial attractiveness of SIPH systems in India. A case of solar process heating in dairy industry has been presented to demonstrate the relative efficacy of different incentives on the economics of SIPH systems in terms of their impact on levelized cost of useful thermal energy delivered. Finally, policy implications of the results obtained have been discussed.

Low molecular weight block copolymers as plasticizers for polystyrene

DEFF Research Database (Denmark)

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

2005-01-01

/mol and minimum polystyrene content of 50 w/w%, which by us is predicted as the limits for solubility of polystyrene-b-alkyl in polystyrene. DSC showed polystyrene was plasticized, as seen by a reduction in glass transition temperature, by block copolymers consisting of a polystyrene block with molecular weight...... of approximately 1 kg/mol and an alkyl block with a molecular weight of approximately of 0.3 kg/mol. The efficiency of the block copolymers as plasticizers increases with decreasing molecular weight and polystyrene content. In addition, polystyrene-b-alkyl is found to be an efficient plasticizer also...... for polystyrene-b-polyisoprene-b-polystyrene (SIS) block copolymers. The end use properties of SIS plasticized with polystyrene-b-alkyl, measured as tensile strength, is higher than for SIS plasticized with dioctyl adipate. The polystyrene-b-polybutadiene-b-polystyrene and polystyrene-bpoly(propylene glycol...

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

Science.gov (United States)

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

2009-01-01

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

The effect of gamma irradiation and shelf aging in air on the oxidation of ultra-high molecular weight polyethylene

International Nuclear Information System (INIS)

Al-Ma'adeed, M.A.; Al-Qaradawi, I.Y.; Madi, N.; Al-Thani, N.J.

2006-01-01

This study has investigated the effect of shelf aging, for up to one year in air, on the properties of gamma-irradiated ultra-high molecular weight polyethylene (UHMWPE). A variety of techniques were used to characterize the properties of treated samples. Differential scanning calorimetery (DSC) was used to characterize the morphology. The extent of cross-linking in a polymer network was detected by swelling measurements. The durometer hardness test was used to measure the relative hardness of this material, and changes in density were also measured. Results from all these measurements were combined to explain the changes in the microstructure of the aged, irradiated UHMWPE. This study shows that crystallinity is increased with radiation dose and with aging due to chain scission, which leads to a reduction in the molecular weight of the material. This allows the chains to rearrange to form crystalline regions. Positron annihilation lifetime spectroscopy confirms these conclusions. Fractional free volumes have been deduced from lifetime parameters, which correlate with the data obtained by the other techniques

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

NARCIS (Netherlands)

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

2017-01-01

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

Surface functionalization of solid state ultra-high molecular weight polyethylene through chemical grafting

Science.gov (United States)

Sherazi, Tauqir A.; Rehman, Tayyiba; Naqvi, Syed Ali Raza; Shaikh, Ahson Jabbar; Shahzad, Sohail Anjum; Abbas, Ghazanfar; Raza, Rizwan; Waseem, Amir

2015-12-01

The surface of ultra-high molecular weight polyethylene (UHMWPE) powder was functionalized with styrene using chemical grafting technique. The grafting process was initiated through radical generation on base polymer matrix in the solid state by sodium thiosulfate, while peroxides formed at radical sites during this process were dissociated by ceric ammonium nitrate. Various factors were optimized and reasonably high level of monomer grafting was achieved, i.e., 15.6%. The effect of different acids as additive and divinyl benzene (DVB) as a cross-linking agent was also studied. Post-grafting sulfonation was conducted to introduce the ionic moieties to the grafted polymer. Ion-exchange capacity (IEC) was measured experimentally and is found to be 1.04 meq g-1, which is in close agreement with the theoretical IEC values. The chemical structure of grafted and functionalized polymer was characterized by attenuated total reflection infrared spectroscopy (ATR-FTIR) and thermal properties were investigated by thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Thermal analysis depicts that the presence of radicals on the polymer chain accelerates the thermal decomposition process. The results signify that the chemical grafting is an effective tool for substantial surface modification and subsequent functionalization of polyethylene.

Resilient Amorphous Networks Prepared by Photo-Crosslinking High-Molecular-Weight D,L-Lactide and Trimethylene Carbonate Macromers: Mechanical Properties and Shape-Memory Behavior

NARCIS (Netherlands)

Sharifi, Shahriar; Grijpma, Dirk W.

2012-01-01

Tough networks are prepared by photo-crosslinking high-molecular-weight DLLA and TMC macromers. These amorphous networks exhibit tunable thermal and mechanical properties and have excellent shape-memory features. Variation of the monomer ratio allows adjustment of Tg between approximately −13 and

Ionizing radiation effect study by electron beam on ultra high molecular weight polyethylene virgin and recycled industrial

International Nuclear Information System (INIS)

Rosario, Salmo Cordeiro do

2006-01-01

Ultra High Molecular Weight Polyethylene (UHMWPE) is an engineering plastic which has several applications, chiefly, in specific areas of the industry and medicine. UHMWPE can be even for other applications such as: port fenders, current guide, bucket coating, silos and gutters, plugs, pulleys and surgical prosthesis. This range of applications is due to the excellent technical characteristics that this material owns, such as; high resistance to wear, high resistance to impact, anti-adherence, non toxic, excellent chemical resistance, low specific weight, easy mill processing, and high resistance to fatigue. The UHMWPE type used in this work were UTEC 3041 and UTEC 6541 of the Braskem. The recycling process of UHMWPE raised much interest, because the utilization of this raw material grew over 600% in the last decade, becoming one of the most used engineering plastics for attainment of mill processed parts after polyamide. As the utilization of this polymer in the manufacturing of parts for machinery has grown, its waste is very big, because the rest of this material is thrown out, usually not being reused. The goal of this work is to recycle the UHMWPE UTEC 3041 and study the properties of this recycled and virgin material and compare the results between both with these materials submitted to different radiation dose. (author)

Influences of gamma irradiation treatment on the molecular weight of chitosan

International Nuclear Information System (INIS)

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

2013-01-01

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

Emotional lability and affective synchrony in borderline personality disorder.

Science.gov (United States)

Schoenleber, Michelle; Berghoff, Christopher R; Tull, Matthew T; DiLillo, David; Messman-Moore, Terri; Gratz, Kim L

2016-07-01

Extant research on emotional lability in borderline personality disorder (BPD) has focused almost exclusively on lability of individual emotions or emotion types, with limited research considering how different types of emotions shift together over time. Thus, this study examined the temporal dynamics of emotion in BPD at the level of both individual emotions (i.e., self-conscious emotions [SCE], anger, and anxiety) and mixed emotions (i.e., synchrony between emotions). One hundred forty-four women from the community completed a diagnostic interview and laboratory study involving 5 emotion induction tasks (each of which was preceded and followed by a 5-min resting period or neutral task). State ratings of SCE, anger, and anxiety were provided at 14 time points (before and after each laboratory task and resting period). Hierarchical linear modeling results indicate that women with BPD reported greater mean levels of SCE and Anxiety (but not Anger), and greater lability of Anxiety. Women with BPD also exhibited greater variability in lability of all 3 emotions (suggestive of within-group differences in the relevance of lability to BPD). Results also revealed synchrony (i.e., positive relations) between each possible pair of emotions, regardless of BPD status. Follow-up regression analyses suggest the importance of accounting for lability when examining the role of synchrony in BPD, as the relation of SCE-Anger synchrony to BPD symptom severity was moderated by Anger and SCE lability. Specifically, synchronous changes in SCE and Anger were associated with greater BPD symptom severity when large shifts in SCE were paired with minor shifts in Anger. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Solution pH and oligoamine molecular weight dependence of the transition from monolayer to multilayer adsorption at the air-water interface from sodium dodecyl sulfate/oligoamine mixtures.

Science.gov (United States)

Halacheva, S S; Penfold, J; Thomas, R K; Webster, J R P

2013-05-14

Neutron reflectivity and surface tension have been used to investigate the solution pH and oligoamine molecular weight dependence of the adsorption of sodium dodecyl sulfate (SDS)/oligoamine mixtures at the air-water interface. For diethylenetriamine, triamine, or triethylenetetramine, tetramine mixed with SDS, there is monolayer adsorption at pH 7 and 10, and multilayer adsorption at pH 3. For the slightly higher molecular weight tetraethylenepentamine, pentamine, and pentaethylenehexamine, hexamine, the adsorption is in the form of a monolayer at pH 3 and multilayers at pH 7 and 10. Hence, there is a pH driven transition from monolayer to multilayer adsorption, which shifts from low pH to higher pH as the oligoamine molecular weight increases from tetramine to pentamine. This results from the relative balance between the electrostatic attraction between the SDS and amine nitrogen group which decreases as the charge density decreases with increasing pH, the ion-dipole interaction between the amine nitrogen and SDS sulfate group which is dominant at higher pH, and the hydrophobic interalkyl chain interaction between bound SDS molecules which changes with oligoamine molecular weight.

Physico-chemical characterization of polyethylene of ultra high molecular weight modified with gamma irradiation and heavy ions

International Nuclear Information System (INIS)

Lagarde, M; Del Grosso, M; Fasce, D; Dommarco, R; Laino, S; Fasce, L.A

2012-01-01

The ultra high molecular weight polyethylene (UHMWPE) is a biomaterial widely used in total joint replacement. In this work, the effect of two different irradiation techniques on UHMWPE is analyzed. One technique involves gamma irradiation (γ) followed by a thermal treatment, thus modifying the material bulk. The other implies swift heavy ion irradiation (SHI), which have an effect only on the near surface layers. The surface nanomechanical properties are evaluated from depth sensing indentation experiments, while changes in crystallinity and chemical structure are determined by DSC and Raman spectroscopy. The results show that even when both techniques are able to improve the UHMWPE wear behavior, the effect on other mechanical properties and molecular structure modification is different. The γ irradiated sample exhibits lower crystallinity, hardness and modulus than the pristine UHMWPE, while the SHI irradiated sample exhibits higher crystallinity and enhanced mechanical properties than the later

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

Science.gov (United States)

Ohkuma, Takahiro; Kremer, Kurt; Daoulas, Kostas

2018-05-01

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

Exploration of high harmonic fast wave heating on the National Spherical Torus Experiment

International Nuclear Information System (INIS)

Wilson, J.R.; Bell, R.E.; Bernabei, S.; Bitter, M.; Gates, D.; Hosea, J.; Le Blanc, B.; Medley, S.; Menard, J.; Mueller, D.; Ono, M.; Phillips, C.K.; Rosenberg, A.; Bonoli, P.; Mau, T.K.; Pinsker, R.I.; Raman, R.; Ryan, P.; Swain, D.; Wilgen, J.

2003-01-01

High harmonic fast wave (HHFW) heating has been proposed as a particularly attractive means for plasma heating and current drive in the high beta plasmas that are achievable in spherical torus (ST) devices. The National Spherical Torus Experiment (NSTX) [M. Ono, S. M. Kaye, S. Neumeyer et al., in Proceedings of the 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque, 1999 (IEEE, Piscataway, NJ, 1999), p. 53] is such a device. An rf heating system has been installed on the NSTX to explore the physics of HHFW heating, current drive via rf waves and for use as a tool to demonstrate the attractiveness of the ST concept as a fusion device. To date, experiments have demonstrated many of the theoretical predictions for HHFW. In particular, strong wave absorption on electrons over a wide range of plasma parameters and wave parallel phase velocities, wave acceleration of energetic ions, and indications of current drive for directed wave spectra have been observed. In addition HHFW heating has been used to explore the energy transport properties of NSTX plasmas, to create H-mode discharges with a large fraction of bootstrap current and to control the plasma current profile during the early stages of the discharge

Structure characterization of the central repetitive domain of high molecular weight gluten proteins .2. Characterization in solution and in the dry state

NARCIS (Netherlands)

van Dijk, A.A.; De Boef, E.; Bekkers, A.; van Wijk, L.L.; van Swieten, E.; Hamer, R.J.; Robillard, G.T.

The structure of the central repetitive domain of high molecular weight (HMW) wheat gluten proteins was characterized in solution and in the dry state using HMW proteins Bx6 and Bx7 and a subcloned, bacterially expressed part of the repetitive domain of HMW Dx5. Model studies of the HMW consensus

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

Science.gov (United States)

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.

Design and testing of high temperature micro-ORC test stand using Siloxane as working fluid

Science.gov (United States)

Turunen-Saaresti, Teemu; Uusitalo, Antti; Honkatukia, Juha

2017-03-01

Organic Rankine Cycle is a mature technology for many applications e.g. biomass power plants, waste heat recovery and geothermal power for larger power capacity. Recently more attention is paid on an ORC utilizing high temperature heat with relatively low power. One of the attractive applications of such ORCs would be utilization of waste heat of exhaust gas of combustion engines in stationary and mobile applications. In this paper, a design procedure of the ORC process is described and discussed. The analysis of the major components of the process, namely the evaporator, recuperator, and turbogenerator is done. Also preliminary experimental results of an ORC process utilizing high temperature exhaust gas heat and using siloxane MDM as a working fluid are presented and discussed. The turbine type utilized in the turbogenerator is a radial inflow turbine and the turbogenerator consists of the turbine, the electric motor and the feed pump. Based on the results, it was identified that the studied system is capable to generate electricity from the waste heat of exhaust gases and it is shown that high molecular weight and high critical temperature fluids as the working fluids can be utilized in high-temperature small-scale ORC applications. 5.1 kW of electric power was generated by the turbogenerator.

Lability of nanoparticulate metal complexes in electrochemical speciation analysis

DEFF Research Database (Denmark)

van Leeuwen, Herman P.; Town, Raewyn M.

2016-01-01

Lability concepts are elaborated for metal complexes with soft (3D) and hard (2D) aqueous nanoparticles. In the presence of a non-equilibrium sensor, e.g. a voltammetric electrode, the notion of lability for nanoparticulate metal complexes, M-NP, reflects the ability of the M-NP to maintain...... equilibrium with the reduced concentration of the electroactive free M2+ in its diffusion layer. Since the metal ion binding sites are confined to the NP body, the conventional reaction layer in the form of a layer adjacent to the electrode surface is immaterial. Instead an intraparticulate reaction zone may...... of the electrochemical technique is crucial in the lability towards the electrode surface. In contrast, for nanoparticulate complexes it is the dynamics of the exchange of the electroactive metal ion with the surrounding medium that governs the effective lability towards the electrode surface....

Pharmacological ascorbate and ionizing radiation (IR increase labile iron in pancreatic cancer

Directory of Open Access Journals (Sweden)

Justin C. Moser

2014-01-01

Full Text Available Labile iron, i.e. iron that is weakly bound and is relatively unrestricted in its redox activity, has been implicated in both the pathogenesis as well as treatment of cancer. Two cancer treatments where labile iron may contribute to their mechanism of action are pharmacological ascorbate and ionizing radiation (IR. Pharmacological ascorbate has been shown to have tumor-specific toxic effects due to the formation of hydrogen peroxide. By catalyzing the oxidation of ascorbate, labile iron can enhance the rate of formation of hydrogen peroxide; labile iron can also react with hydrogen peroxide. Here we have investigated the magnitude of the labile iron pool in tumor and normal tissue. We also examined the ability of pharmacological ascorbate and IR to change the size of the labile iron pool. Although a significant amount of labile iron was seen in tumors (MIA PaCa-2 cells in athymic nude mice, higher levels were seen in murine tissues that were not susceptible to pharmacological ascorbate. Pharmacological ascorbate and irradiation were shown to increase the labile iron in tumor homogenates from this murine model of pancreatic cancer. As both IR and pharmacological ascorbate may rely on labile iron for their effects on tumor tissues, our data suggest that pharmacological ascorbate could be used as a radio-sensitizing agent for some radio-resistant tumors.

Heat-stable proteins and abscisic acid action in barley aleurone cells

International Nuclear Information System (INIS)

Jacobsen, J.V.; Shaw, D.C.

1989-01-01

[ 35 S]Methionine labeling experiments showed that abscisic acid (ABA) induced the synthesis of at least 25 polypeptides in mature barley (Hordeum vulgare) aleurone cells. The polypeptides were not secreted. Whereas most of the proteins extracted from aleurone cells were coagulated by heating to 100 degree C for 10 minutes, most of the ABA-induced polypeptides remained in solution (heat-stable). ABA had little effect on the spectrum of polypeptides that were synthesized and secreted by aleurone cells, and most of these secreted polypeptides were also heat-stable. Coomassie blue staining of sodium dodecyl sulfate polyacrylamide gels indicated that ABA-induced polypeptides already occurred in high amounts in mature aleurone layers having accumulated during grain development. About 60% of the total protein extracted from mature aleurone was heat stable. Amino acid analyses of total preparations of heat-stable and heat-labile proteins showed that, compared to heat-labile proteins, heat-stable intracellular proteins were characterized by higher glutamic acid/glutamine (Glx) and glycine levels and lower levels of neutral amino acids. Secreted heat-stable proteins were rich in Glx and proline. The possibilities that the accumulation of the heat-stable polypeptides during grain development is controlled by ABA and that the function of these polypeptides is related to their abundance and extraordinary heat stability are considered

Serum high molecular weight complex of adiponectin correlates better with glucose tolerance than total serum adiponectin in Indo-Asian males.

Science.gov (United States)

Fisher, F F M; Trujillo, M E; Hanif, W; Barnett, A H; McTernan, P G; Scherer, P E; Kumar, S

2005-06-01

It is well established that total systemic adiponectin is reduced in type 2 diabetic subjects. To date most studies have been concerned with the singular full-length protein or proteolytically cleaved globular domain. It is, however, apparent that the native protein circulates in serum as a lower molecular weight hexamer and as larger multimeric structures of high molecular weight (HMW). In this study we address the clinical significance of each form of the protein with respect to glucose tolerance. Serum was obtained from 34 Indo-Asian male subjects (BMI 26.5+/-3.1; age 52.15+/-10.14 years) who had undertaken a 2-h oral glucose tolerance test. An aliquot of serum was fractionated using velocity sedimentation followed by reducing SDS-PAGE. Western blots were probed for adiponectin, and HMW adiponectin as a percentage of total adiponectin (percentage of higher molecular weight adiponectin [S(A)] index) was calculated from densitometry readings. Total adiponectin was measured using ELISA; leptin, insulin and IL-6 were determined using ELISA. Analysis of the cohort demonstrated that total adiponectin (r = 0.625, p = 0.0001), fasting insulin (r = -0.354, p = 0.040) and age (r = 0.567, p = 0.0001) correlated with S(A). S(A) showed a tighter, inverse correlation with 2-h glucose levels (r = -0.58, p = 0.0003) than total adiponectin (r = -0.38, p = 0.0001). This study demonstrates the importance of the S(A) index as a better determinant of glucose intolerance than measurements of total adiponectin. Our findings suggest that HMW adiponectin is the active form of the protein.

Allele Variants of Enterotoxigenic Escherichia coli Heat-Labile Toxin Are Globally Transmitted and Associated with Colonization Factors

KAUST Repository

Joffré , Enrique; von Mentzer, Astrid; Abd El Ghany, Moataz; Oezguen, Numan; Savidge, Tor; Dougan, Gordon; Svennerholm, Ann-Mari; Sjö ling, Å sa

2015-01-01

Enterotoxigenic Escherichia coli (ETEC) is a significant cause of morbidity and mortality in the developing world. ETEC-mediated diarrhea is orchestrated by heat-labile toxin (LT) and heat-stable toxins (STp and STh), acting in concert with a repertoire of more than 25 colonization factors (CFs). LT, the major virulence factor, induces fluid secretion after delivery of a monomeric ADP-ribosylase (LTA) and its pentameric carrier B subunit (LTB). A study of ETEC isolates from humans in Brazil reported the existence of natural LT variants. In the present study, analysis of predicted amino acid sequences showed that the LT amino acid polymorphisms are associated with a geographically and temporally diverse set of 192 clinical ETEC strains and identified 12 novel LT variants. Twenty distinct LT amino acid variants were observed in the globally distributed strains, and phylogenetic analysis showed these to be associated with different CF profiles. Notably, the most prevalent LT1 allele variants were correlated with major ETEC lineages expressing CS1 + CS3 or CS2 + CS3, and the most prevalent LT2 allele variants were correlated with major ETEC lineages expressing CS5 + CS6 or CFA/I. LTB allele variants generally exhibited more-stringent amino acid sequence conservation (2 substitutions identified) than LTA allele variants (22 substitutions identified). The functional impact of LT1 and LT2 polymorphisms on virulence was investigated by measuring total-toxin production, secretion, and stability using GM1-enzyme-linked immunosorbent assays (GM1-ELISA) and in silico protein modeling. Our data show that LT2 strains produce 5-fold more toxin than LT1 strains (P < 0.001), which may suggest greater virulence potential for this genetic variant. Our data suggest that functionally distinct LT-CF variants with increased fitness have persisted during the evolution of ETEC and have spread globally.

Allele Variants of Enterotoxigenic Escherichia coli Heat-Labile Toxin Are Globally Transmitted and Associated with Colonization Factors

KAUST Repository

Joffré, Enrique

2015-01-15

Enterotoxigenic Escherichia coli (ETEC) is a significant cause of morbidity and mortality in the developing world. ETEC-mediated diarrhea is orchestrated by heat-labile toxin (LT) and heat-stable toxins (STp and STh), acting in concert with a repertoire of more than 25 colonization factors (CFs). LT, the major virulence factor, induces fluid secretion after delivery of a monomeric ADP-ribosylase (LTA) and its pentameric carrier B subunit (LTB). A study of ETEC isolates from humans in Brazil reported the existence of natural LT variants. In the present study, analysis of predicted amino acid sequences showed that the LT amino acid polymorphisms are associated with a geographically and temporally diverse set of 192 clinical ETEC strains and identified 12 novel LT variants. Twenty distinct LT amino acid variants were observed in the globally distributed strains, and phylogenetic analysis showed these to be associated with different CF profiles. Notably, the most prevalent LT1 allele variants were correlated with major ETEC lineages expressing CS1 + CS3 or CS2 + CS3, and the most prevalent LT2 allele variants were correlated with major ETEC lineages expressing CS5 + CS6 or CFA/I. LTB allele variants generally exhibited more-stringent amino acid sequence conservation (2 substitutions identified) than LTA allele variants (22 substitutions identified). The functional impact of LT1 and LT2 polymorphisms on virulence was investigated by measuring total-toxin production, secretion, and stability using GM1-enzyme-linked immunosorbent assays (GM1-ELISA) and in silico protein modeling. Our data show that LT2 strains produce 5-fold more toxin than LT1 strains (P < 0.001), which may suggest greater virulence potential for this genetic variant. Our data suggest that functionally distinct LT-CF variants with increased fitness have persisted during the evolution of ETEC and have spread globally.

The role of heat shock protein 90 in the regulation of tumor cell apoptosis.

Science.gov (United States)

Kaigorodova, E V; Ryazantseva, N V; Novitskii, V V; Belkina, M V; Maroshkina, A N

2011-02-01

Programmed death of Jurkat tumor cells was studied under conditions of culturing with 17-AAG selective inhibitor of heat shock protein with a molecular weight of 90 kDa and etoposide. Apoptosis realization was evaluated by fluorescent microscopy with FITC-labeled annexin V and propidium iodide. Activity of caspase-3 was evaluated spectrophotometrically. Inhibition of heat shock protein with a molecular weight of 90 kDa activated the apoptotic program in Jurkat tumor cells and etoposide-induced apoptosis. The heat shock protein with a molecular weight of 90 kDa acted as apoptosis inhibitor in tumor cells.

Kinetics of Low Temperature Polyester Dyeing with High Molecular Weight Disperse Dyes by Solvent Microemulsion and AgroSourced Auxiliaries

OpenAIRE

Shahram Radei; F. Javier Carrión-Fité; Mònica Ardanuy; José María Canal

2018-01-01

This work focused on the evaluation of the kinetics of dyeing polyester fabrics with high molecular weight disperse dyes, at low temperature by solvent microemulsion. This study also compared the effect of two non-toxic agro-sourced auxiliaries (o-vanillin and coumarin) using a non-toxic organic solvent. A dyeing bath consisting of a micro-emulsion system involving a small proportion of n-butyl acetate was used, and the kinetics of dyeing were analysed at four temperatures (83, 90, 95 and 100...

Transient acidosis while retrieving a fear-related memory enhances its lability

Science.gov (United States)

Du, Jianyang; Price, Margaret P; Taugher, Rebecca J; Grigsby, Daniel; Ash, Jamison J; Stark, Austin C; Hossain Saad, Md Zubayer; Singh, Kritika; Mandal, Juthika; Wemmie, John A; Welsh, Michael J

2017-01-01

Attenuating the strength of fearful memories could benefit people disabled by memories of past trauma. Pavlovian conditioning experiments indicate that a retrieval cue can return a conditioned aversive memory to a labile state. However, means to enhance retrieval and render a memory more labile are unknown. We hypothesized that augmenting synaptic signaling during retrieval would increase memory lability. To enhance synaptic transmission, mice inhaled CO2 to induce an acidosis and activate acid sensing ion channels. Transient acidification increased the retrieval-induced lability of an aversive memory. The labile memory could then be weakened by an extinction protocol or strengthened by reconditioning. Coupling CO2 inhalation to retrieval increased activation of amygdala neurons bearing the memory trace and increased the synaptic exchange from Ca2+-impermeable to Ca2+-permeable AMPA receptors. The results suggest that transient acidosis during retrieval renders the memory of an aversive event more labile and suggest a strategy to modify debilitating memories. DOI: http://dx.doi.org/10.7554/eLife.22564.001 PMID:28650315

Direct Photolithography on Molecular Crystals for High Performance Organic Optoelectronic Devices.

Science.gov (United States)

Yao, Yifan; Zhang, Lei; Leydecker, Tim; Samorì, Paolo

2018-05-23

Organic crystals are generated via the bottom-up self-assembly of molecular building blocks which are held together through weak noncovalent interactions. Although they revealed extraordinary charge transport characteristics, their labile nature represents a major drawback toward their integration in optoelectronic devices when the use of sophisticated patterning techniques is required. Here we have devised a radically new method to enable the use of photolithography directly on molecular crystals, with a spatial resolution below 300 nm, thereby allowing the precise wiring up of multiple crystals on demand. Two archetypal organic crystals, i.e., p-type 2,7-diphenyl[1]benzothieno[3,2- b][1]benzothiophene (Dph-BTBT) nanoflakes and n-type N, N'-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) nanowires, have been exploited as active materials to realize high-performance top-contact organic field-effect transistors (OFETs), inverter and p-n heterojunction photovoltaic devices supported on plastic substrate. The compatibility of our direct photolithography technique with organic molecular crystals is key for exploiting the full potential of organic electronics for sophisticated large-area devices and logic circuitries, thus paving the way toward novel applications in plastic (opto)electronics.

Irreversible thermodynamic analysis and application for molecular heat engines

Science.gov (United States)

Lucia, Umberto; Açıkkalp, Emin

2017-09-01

Is there a link between the macroscopic approach to irreversibility and microscopic behaviour of the systems? Consumption of free energy keeps the system away from a stable equilibrium. Entropy generation results from the redistribution of energy, momentum, mass and charge. This concept represents the essence of the thermodynamic approach to irreversibility. Irreversibility is the result of the interaction between systems and their environment. The aim of this paper is to determine lost works in a molecular engine and compare results with macro (classical) heat engines. Firstly, irreversible thermodynamics are reviewed for macro and molecular cycles. Secondly, irreversible thermodynamics approaches are applied for a quantum heat engine with -1/2 spin system. Finally, lost works are determined for considered system and results show that macro and molecular heat engines obey same limitations. Moreover, a quantum thermodynamic approach is suggested in order to explain the results previously obtained from an atomic viewpoint.

THE IMPORTANCE OF HIGH-MOLECULAR-WEIGHT GLUTENIN SUBUNITS FOR WHEAT QUALITY EVALUATION

Directory of Open Access Journals (Sweden)

G. Drezner

2006-06-01

Full Text Available High-molecular-weight glutenin subunits (HMW-GS composition was analyzed by sodium-dodecyl-sulfat-polyacrilamid-gel electrophoresis (SDS-PAGE, while the quantitative determination of total HMW-GS was obtained by reversed phase- high performance liquid chromatography (RP-HPLC. Considering HMW-GS composition, the most frequent subunits at Glu-A1 locus were N, at Glu-B1 locus 7+9 and at Glu-D1 locus 2+12. The cultivars with the GS 5+10 at Glu-D1 locus have shown better technological characteristics in contrast to cultivars with the GS 2+12. The cultivars Žitarka, Srpanjka, Barbara, Klara and Golubica in spite of presence HMW-GS 2+12 have shown very good and good technological properties because they had optimal proportions (>10% of total HMW-GS. The results of the linear correlation analysis between quality parameters and HMW-GS composition have shown significant (P<0.05 positive influence of HMW-GS (Glu-1 score on sedimentation value (r=0.55, Gluten Index (r=0.72, dough energy (r=0.61, maximum resistance (r=0.64 and resistance to extensibility ratio (r=0.58. The influence of HMW GS proportions on technological parameters, compared to HMW-GS composition, was more pronounced on protein content (r=0.82, dough development time (r=0.70, degree of softening (r=-0.90, dough energy (r=0.74 and loaf volume (r=0.65.

Determination of viscosity-average molecular weight of chitosan using intrinsic viscosity measurement

International Nuclear Information System (INIS)

Norzita Yacob; Norhashidah Talip; Maznah Mahmud; Nurul Aizam Idayu Mat Sani; Nor Akma Samsuddin; Norafifah Ahmad Fabillah

2013-01-01

Determination of molecular weight by intrinsic viscosity measurement is a simple method for characterization of chitosan. To study the effect of radiation on molecular weight, chitosan was first irradiated using electron beam at different doses prior to measurement. Different concentrations of chitosan were prepared and measurement was done at room temperature. The flow time data was used to calculate the intrinsic viscosity by extrapolating the reduced viscosity to zero concentration. The value of intrinsic viscosity was then recalculated into the viscosity-average molecular weight using Mark-Houwink equation. (Author)

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

International Nuclear Information System (INIS)

Norzita Yacob; Norhashidah Talip; Maznah Mahmud

2011-01-01

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

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

Science.gov (United States)

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

2010-01-01

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

Relationships between browsing damage and the species dominance by the highly food-attractive and less food-attractive trees

Directory of Open Access Journals (Sweden)

Petr Čermák

2011-01-01

Full Text Available The paper analyses data on the browsing damage to Acer pseudoplatanus, Carpinus betulus, Fraxinus excelsior, Quercus spp., Tilia cordata and Fagus sylvatica. Field research was carried out in the period 2007–2010 and analysed data came from 33 transects at 10 localities with the various abundance of game in the CR (everywhere Capreolus capreolus, on several plots also Cervus elaphus, Ovis musimon or Dama dama. Trees were monitored up to a height of 150 cm in natural regeneration under stands and in plantations and the occurrence was noted of new browsing damage. Differences between the percentage of damaged individuals of the given species of a food-attractive species (A. p., C. b., F. e. and the percentage of damaged individuals of all tree species on a transect as well as the proportion of these parameters correlate negatively with the given species dominance and thus, they appear to be suitable parameters for the analysis of relationships between the damage intensity and dominance. The higher the percentage proportions of highly food-attractive species and the lower the percentage of less-attractive species, the lower the relative intensity of damage to highly food-attractive species. At the same time, the higher the percentage proportion of highly food-attractive species and the lower the percentage of less-attractive species then the lower a difference between damage to less food-attractive species and all species.

Screen time, weight status and the self-concept of physical attractiveness in adolescents.

Science.gov (United States)

Suchert, Vivien; Hanewinkel, Reiner; Isensee, Barbara

2016-04-01

Adolescents in modern societies spend about 3 h per day in front of small recreational screens. The present study aims at investigating the relationships between screen time and different indicators of overweight. In addition, associations with the self-concept of physical attractiveness and perceived weight status will be examined. In a total sample of 1228 students (47.5% girls) aged 12-17 years (M = 13.74, SD = 0.68) cross-sectional associations were determined by conducting multiple linear regression analyses. Screen time showed a significant positive dose-response relationship with body mass index percentile, waist circumference, body fat, waist-to-height-ratio, and a negative association with self-concept of physical attractiveness independent of age, gender and moderate to vigorous physical activity. Thus, screen time seems to be associated with adolescent overweight, abdominal obesity, and body dissatisfaction. Reducing adolescents' screen time could be a promising approach for primary prevention of obesity and for the promotion of a positive physical self-concept. Copyright © 2016 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

The Role of Attractiveness and Aggression in High School Popularity

Science.gov (United States)

Borch, Casey; Hyde, Allen; Cillessen, Antonius H. N.

2011-01-01

This study examines the effects of physical attractiveness and aggression on popularity among high school students. Previous work has found positive relationships between aggression and popularity and physical attractiveness and popularity. The current study goes beyond this work by examining the interactive effects of physical attractiveness and…

Hybrid Complexes of High and Low Molecular Weight Hyaluronans Highly Enhance HASCs Differentiation: Implication for Facial Bioremodelling

Directory of Open Access Journals (Sweden)

Antonietta Stellavato

2017-11-01

Full Text Available Background/Aims: Adipose-derived Stem Cells (ASCs are used in Regenerative Medicine, including fat grafting, recovery from local tissue ischemia and scar remodeling. The aim of this study was to evaluate hyaluronan based gel effects on ASCs differentiation and proliferation. Methods: Comparative analyses using high (H and low (L molecular weight hyaluronans (HA, hyaluronan hybrid cooperative complexes (HCCs, and high and medium cross-linked hyaluronan based dermal fillers were performed. Human ASCs were characterized by flow cytometry using CD90, CD34, CD105, CD29, CD31, CD45 and CD14 markers. Then, cells were treated for 7, 14 and 21 days with hyaluronans. Adipogenic differentiation was evaluated using Oil red-O staining and expression of leptin, PPAR-γ, LPL and adiponectin using qRT-PCR. Adiponectin was analyzed by immunofluorescence, PPAR-γ and adiponectin were analyzed using western blotting. ELISA assays for adiponectin and leptin were performed. Results: HCCs highly affected ASCs differentiation by up-regulating adipogenic genes and related proteins, that were also secreted in the culture medium. H-HA and L-HA induced a lower level of ASCs differentiation. Conclusion: HCCs-based formulations clearly enhance adipogenic differentiation and proliferation, when compared with linear HA and cross-linked hyaluronans. Injection of HCCs in subdermal fat compartment may recruit and differentiate stem cells in adipocytes, and considerably improving fat tissue renewal.

STATUS REPORT ON DEVELOPMENT OF A HIGH-SPEED HIGH-INTENSITY MOLECULAR BEAM

Energy Technology Data Exchange (ETDEWEB)

Knuth, Eldon L.

1963-07-15

Status of a high-speed high-intensity molecular beam under development is described. Bases for designs of the several components are presented. Using an arc-heated source and a hypersonic jet, molecular energies exceeding 1 ev and beam intensities of the order of 10/sup 16/ molecules/ cm/sup 2/ sec are anticipated. A two-disk beam chopper and speed selector provides a means for analyzing the speed distribution in the generated beam, for chopping the beam into bursts of nearly monoenergetic molecules suitable for scattering studies using the time-of-flight technique, and for modulating the beam in order to facilitate detection. A through-flow ionization detector possesses the versatility required for scattering studies using the time-of-flight technique. A sorption pump and a turbo pump serve as central components of alternative pumping systems for the collimating chamber. Using the arc-heated source, the converging nozzle, the conduction-radiation-cooled skimmer, the turbo pump (turning at 3400 rpm), the chopperselector (acting only as a chopper), and the detector, an arc-heated beam is generated and detected. (auth)

Design of Light-Weight High-Entropy Alloys

Directory of Open Access Journals (Sweden)

Rui Feng

2016-09-01

Full Text Available High-entropy alloys (HEAs are a new class of solid-solution alloys that have attracted worldwide attention for their outstanding properties. Owing to the demand from transportation and defense industries, light-weight HEAs have also garnered widespread interest from scientists for use as potential structural materials. Great efforts have been made to study the phase-formation rules of HEAs to accelerate and refine the discovery process. In this paper, many proposed solid-solution phase-formation rules are assessed, based on a series of known and newly-designed light-weight HEAs. The results indicate that these empirical rules work for most compositions but also fail for several alloys. Light-weight HEAs often involve the additions of Al and/or Ti in great amounts, resulting in large negative enthalpies for forming solid-solution phases and/or intermetallic compounds. Accordingly, these empirical rules need to be modified with the new experimental data. In contrast, CALPHAD (acronym of the calculation of phase diagrams method is demonstrated to be an effective approach to predict the phase formation in HEAs as a function of composition and temperature. Future perspectives on the design of light-weight HEAs are discussed in light of CALPHAD modeling and physical metallurgy principles.

[Correlation of molecular weight and nanofiltration mass transfer coefficient of phenolic acid composition from Salvia miltiorrhiza].

Science.gov (United States)

Li, Cun-Yu; Wu, Xin; Gu, Jia-Mei; Li, Hong-Yang; Peng, Guo-Ping

2018-04-01

Based on the molecular sieving and solution-diffusion effect in nanofiltration separation, the correlation between initial concentration and mass transfer coefficient of three typical phenolic acids from Salvia miltiorrhiza was fitted to analyze the relationship among mass transfer coefficient, molecular weight and concentration. The experiment showed a linear relationship between operation pressure and membrane flux. Meanwhile, the membrane flux was gradually decayed with the increase of solute concentration. On the basis of the molecular sieving and solution-diffusion effect, the mass transfer coefficient and initial concentration of three phenolic acids showed a power function relationship, and the regression coefficients were all greater than 0.9. The mass transfer coefficient and molecular weight of three phenolic acids were negatively correlated with each other, and the order from high to low is protocatechualdehyde >rosmarinic acid> salvianolic acid B. The separation mechanism of nanofiltration for phenolic acids was further clarified through the analysis of the correlation of molecular weight and nanofiltration mass transfer coefficient. The findings provide references for nanofiltration separation, especially for traditional Chinese medicine with phenolic acids. Copyright© by the Chinese Pharmaceutical Association.

Thulium heat source for high-endurance and high-energy density power systems

International Nuclear Information System (INIS)

Walter, C.E.; Kammeraad, J.E.; Van Konynenburg, R.; VanSant, J.H.

1991-05-01

We are studying the performance characteristics of radioisotope heat source designs for high-endurance and high-energy-density power systems that use thulium-170. Heat sources in the power range of 5--50 kW th coupled with a power conversion efficiency of ∼30%, can easily satisfy current missions for autonomous underwater vehicles. New naval missions will be possible because thulium isotope power systems have a factor of one-to-two hundred higher endurance and energy density than chemical and electrochemical systems. Thulium-170 also has several other attractive features, including the fact that it decays to stable ytterbium-170 with a half-life of four months. For terrestrial applications, refueling on that time scale should be acceptable in view of the advantage of its benign decay. The heat source designs we are studying account for the requirements of isotope production, shielding, and integration with power conversion components. These requirements are driven by environmental and safety considerations. Thulium is present in the form of thin refractory thulia disks that allow power conversion at high peak temperature. We give estimates of power system state points, performance, mass, and volume characteristics. Monte Carlo radiation analysis provides a detailed assessment of shield requirements and heat transfer under normal and distressed conditions is also considered. 11 refs., 7 figs., 4 tabs

Photo-lability of deep ocean dissolved black carbon

Directory of Open Access Journals (Sweden)

A. Stubbins

2012-05-01

Full Text Available Dissolved black carbon (DBC, defined here as condensed aromatics isolated from seawater via PPL solid phase extraction and quantified as benzenepolycarboxylic acid (BPCA oxidation products, is a significant component of the oceanic dissolved organic carbon (DOC pool. These condensed aromatics are widely distributed in the open ocean and appear to be tens of thousands of years old. As such DBC is regarded as highly refractory. In the current study, the photo-lability of DBC, DOC and coloured dissolved organic matter (CDOM; ultraviolet-visible absorbance were determined over the course of a 28 day irradiation of North Atlantic Deep Water under a solar simulator. During the irradiation DBC fell from 1044 ± 164 nM-C to 55 ± 15 nM-C, a 20-fold decrease in concentration. Dissolved black carbon photo-degradation was more rapid and more extensive than for bulk CDOM and DOC. The concentration of DBC correlated with CDOM absorbance and the quality of DBC indicated by the ratios of different BPCAs correlated with CDOM absorbance spectral slope, suggesting the optical properties of CDOM may provide a proxy for both DBC concentrations and quality in natural waters. Further, the photo-lability of components of the DBC pool increased with their degree of aromatic condensation. These trends indicate that a continuum of compounds of varying photo-lability exists within the marine DOC pool. In this continuum, photo-lability scales with aromatic character, specifically the degree of condensation. Scaling the rapid photo-degradation of DBC to rates of DOC photo-mineralisation for the global ocean leads to an estimated photo-chemical half-life for oceanic DBC of less than 800 years. This is more than an order of magnitude shorter than the apparent age of DBC in the ocean. Consequently, photo-degradation is posited as the primary sink for oceanic DBC and the apparent survival of DBC molecules in the oceans for millennia appears to be facilitated not by their

Assessment of contaminant lability during phytoremediation of polycyclic aromatic hydrocarbon impacted soil

Energy Technology Data Exchange (ETDEWEB)

Zakia D. Parrish; M. Katherine Banks; A. Paul Schwab [Connecticut Agricultural Experiment Station, New Haven, CT (United States). Department of Soil and Water

2005-09-15

Polycyclic aromatic hydrocarbons (PAHs) are recalcitrant compounds, some of which are known carcinogens, often found in high residual soil concentrations at industrial sites. Recent research has confirmed that phytoremediation holds promise as a low-cost treatment method for PAH contaminated soil. In this study, the lability of soil bound PAHs in the rhizosphere was estimated using solid phase extraction resin. An extraction time of 14 days was determined to be appropriate for this study. Resin-extractable PAHs, which are assumed to be more bioavailable, decreased during plant treatments. Significant reductions in the labile concentrations of several PAH compounds occurred over 12 months of plant growth. The differences in concentration between the unplanted and the planted soil indicate that the presence of plant roots, in addition to the passage of time, contributes to reduction in the bioavailability of target PAHs. The lability of sorbed contaminants is modified by the presence of plants. Remediation coupled with plant treatment can change the bioavailability of contaminants in soil.

Assessment of contaminant lability during phytoremediation of polycyclic aromatic hydrocarbon impacted soil

Energy Technology Data Exchange (ETDEWEB)

Parrish, Zakia D. [Department of Soil and Water, Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT 06511 (United States); Banks, M. Katherine [School of Civil Engineering, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051 (United States)]. E-mail: kbanks@ecn.purdue.edu; Schwab, A. Paul [Department of Agronomy, Purdue University, 915 W. State Street, West Lafayette, IN 47907-2054 (United States)

2005-09-15

Polycyclic aromatic hydrocarbons (PAHs) are recalcitrant compounds, some of which are known carcinogens, often found in high residual soil concentrations at industrial sites. Recent research has confirmed that phytoremediation holds promise as a low-cost treatment method for PAH contaminated soil. In this study, the lability of soil bound PAHs in the rhizosphere was estimated using solid phase extraction resin. An extraction time of 14 days was determined to be appropriate for this study. Resin-extractable PAHs, which are assumed to be more bioavailable, decreased during plant treatments. Significant reductions in the labile concentrations of several PAH compounds occurred over 12 months of plant growth. The differences in concentration between the unplanted and the planted soil indicate that the presence of plant roots, in addition to the passage of time, contributes to reduction in the bioavailability of target PAHs. - The lability of sorbed contaminants is modified by the presence of plants. Remediation coupled with plant treatment can change the bioavailability of contaminants in soil.

Assessment of contaminant lability during phytoremediation of polycyclic aromatic hydrocarbon impacted soil

International Nuclear Information System (INIS)

Parrish, Zakia D.; Banks, M. Katherine; Schwab, A. Paul

2005-01-01

Polycyclic aromatic hydrocarbons (PAHs) are recalcitrant compounds, some of which are known carcinogens, often found in high residual soil concentrations at industrial sites. Recent research has confirmed that phytoremediation holds promise as a low-cost treatment method for PAH contaminated soil. In this study, the lability of soil bound PAHs in the rhizosphere was estimated using solid phase extraction resin. An extraction time of 14 days was determined to be appropriate for this study. Resin-extractable PAHs, which are assumed to be more bioavailable, decreased during plant treatments. Significant reductions in the labile concentrations of several PAH compounds occurred over 12 months of plant growth. The differences in concentration between the unplanted and the planted soil indicate that the presence of plant roots, in addition to the passage of time, contributes to reduction in the bioavailability of target PAHs. - The lability of sorbed contaminants is modified by the presence of plants. Remediation coupled with plant treatment can change the bioavailability of contaminants in soil

Photoluminescence of ultra-high molecular weight polyethylene modified by fast atom bombardment

International Nuclear Information System (INIS)

Toth, S.; Fuele, M.; Veres, M.; Pocsik, I.; Koos, M.; Toth, A.; Ujvari, T.; Bertoti, I.

2006-01-01

An increase in the application potential of the ultra-high molecular weight polyethylene (UHMWPE) may be achieved by producing a hard, wear resistant carbonaceous modified surface layer on it. In this study the surface of UHMWPE samples was treated by 1 keV N, H and He fast atom bombardment (FAB) to obtain amorphous carbon surface layer which produces an enhancement of microhardness. The untreated and FAB-modified samples were investigated by photoluminescence, infrared, Raman and optical absorption spectroscopy. The FAB-treatment caused a nearly complete disappearance of the characteristic luminescence bands of UHMWPE (at 335, 351, 363 and 381 nm), the appearance of new bands at 459 and 495 nm due to the formation of new recombination levels in the FAB-treated samples. The remarkable decrease in integrated luminescence intensity indicates the appearance of new non-radiative recombination levels caused by FAB treatment. Structural modifications in FAB treated samples result in the development of structural arrangement containing sp 2 bonded carbon sites in rings or chains of different sizes and the electronic levels corresponding to these structural elements are situated in the forbidden gap in the electronic density of states which brings forth the observed changes of the photoluminescence properties

Race and Physical Attractiveness as Criteria for White Subjects' Dating Choices

Science.gov (United States)

Allen, Bem P.

1976-01-01

Experiments involving "desirability for a date" ratings of black and white stimulus persons who varied in attractiveness indicated white male and female subjects gave appreciable weight to race and attractiveness, but females gave race more weight than attractiveness, while attractiveness was given more weight than race by males. (Author)

Book of presentations of the International Workshop on High Temperature Heat Pumps

DEFF Research Database (Denmark)

Modern society moves towards an electrifed energy system based on wind, solarand other renewable sources. Utilizing these sources effciently by heat pumps ishighly attractive and a significant potential for improving the energy system byextensive adaptation of heat pumping technology in all fields...... exists. However, challenges are present for heat pump technology. In particular for high temperature applications like industrial processes and to some extent district heating, heat pumps are not yet commercially available. In some countries the expansion already occurs, but other places the development...... is much more limited. Some obstacles relate to regulations and boundary conditions which may not be favorablefor heat pumps and electrification. But, the level of the technology willprobably also improve with regards to temperature limits, efficiency, capacity, and economy, and hence inherently become...

Electrospinning and characterization of polyamide 66 nanofibers with different molecular weights

Directory of Open Access Journals (Sweden)

Lilia Muller Guerrini

2009-06-01

Full Text Available Polyamide 66 (PA66 nanofibers of different molecular weights were obtained by electrospinning of formic acid solutions. An ionic salt, NaCl, was also added to the solutions to increase the conductivity. PA66 concentrations between 15-17 wt.(%/v and electrical fields between 2.0 and 2.5 kV/cm were the best conditions to produce the smallest nanofibers; however, the addition of NaCl increased the fibers average diameters.The characterization of the fibers was done by scanning electron microscopy (SEM, differential scanning calorimetry (DSC, wide angle X rays diffraction (WAXD and Fourier Transformed Infrared (FTIR. As the molecular weight decreased, the nanofibers average diameters also decreased; however, critical number average and weight average molecular weights were necessary for electrospinning. As the amounts of carboxyl terminal groups (CTG increased, the nanofibers average diameters decreased; however, above CTG's critical values of 8.7 x 10-5 mol.g-1 no electrospinning was possible. The addition of ionic salt increased the electrical conductivity of the solutions and increased the nanofibers' average diameters. By DSC, residual solvent in all the electrospun mats was found; two melting endotherms, one between 248 and 258 °C and the other one between 258 and 267 °C, depending on the sample were also observed. These endotherms were attributed to the melting, re-crystallization and re-melting of the PA66 α-phase. The nanofibers had low % of crystallinity compared to a textile fiber. By WAXS and FTIR, confirmation of the presence of α-phase crystals, of small dimensions and highly imperfect and of a very small amount of β and γ-phases crystals in the nanofibers structure was obtained.

Preparation of High Purity, High Molecular-Weight Chitin from Ionic Liquids for Use as an Adsorbate for the Extraction of Uranium from Seawater

Energy Technology Data Exchange (ETDEWEB)

Rogers, Robin [Univ. of Alabama, Tuscaloosa, AL (United States)

2013-12-21

Ensuring a domestic supply of uranium is a key issue facing the wider implementation of nuclear power. Uranium is mostly mined in Kazakhstan, Australia, and Canada, and there are few high-grade uranium reserves left worldwide. Therefore, one of the most appealing potential sources of uranium is the vast quantity dissolved in the oceans (estimated to be 4.4 billion tons worldwide). There have been research efforts centered on finding a means to extract uranium from seawater for decades, but so far none have resulted in an economically viable product, due in part to the fact that the materials that have been successfully demonstrated to date are too costly (in terms of money and energy) to produce on the necessary scale. Ionic Liquids (salts which melt below 100{degrees}C) can completely dissolve raw crustacean shells, leading to recovery of a high purity, high molecular weight chitin powder and to fibers and films which can be spun directly from the extract solution suggesting that continuous processing might be feasible. The work proposed here will utilize the unprecedented control this makes possible over the chitin fiber a) to prepare electrospun nanofibers of very high surface area and in specific architectures, b) to modify the fiber surfaces chemically with selective extractant capacity, and c) to demonstrate their utility in the direct extraction and recovery of uranium from seawater. This approach will 1) provide direct extraction of chitin from shellfish waste thus saving energy over the current industrial process for obtaining chitin; 2) allow continuous processing of nanofibers for very high surface area fibers in an economical operation; 3) provide a unique high molecular weight chitin not available from the current industrial process, leading to stronger, more durable fibers; and 4) allow easy chemical modification of the large surface areas of the fibers for appending uranyl selective functionality providing selectivity and ease of stripping. The

Preparation of High Purity, High Molecular-Weight Chitin from Ionic Liquids for Use as an Adsorbate for the Extraction of Uranium from Seawater

International Nuclear Information System (INIS)

Rogers, Robin

2013-01-01

Ensuring a domestic supply of uranium is a key issue facing the wider implementation of nuclear power. Uranium is mostly mined in Kazakhstan, Australia, and Canada, and there are few high-grade uranium reserves left worldwide. Therefore, one of the most appealing potential sources of uranium is the vast quantity dissolved in the oceans (estimated to be 4.4 billion tons worldwide). There have been research efforts centered on finding a means to extract uranium from seawater for decades, but so far none have resulted in an economically viable product, due in part to the fact that the materials that have been successfully demonstrated to date are too costly (in terms of money and energy) to produce on the necessary scale. Ionic Liquids (salts which melt below 100 deg C) can completely dissolve raw crustacean shells, leading to recovery of a high purity, high molecular weight chitin powder and to fibers and films which can be spun directly from the extract solution suggesting that continuous processing might be feasible. The work proposed here will utilize the unprecedented control this makes possible over the chitin fiber a) to prepare electrospun nanofibers of very high surface area and in specific architectures, b) to modify the fiber surfaces chemically with selective extractant capacity, and c) to demonstrate their utility in the direct extraction and recovery of uranium from seawater. This approach will 1) provide direct extraction of chitin from shellfish waste thus saving energy over the current industrial process for obtaining chitin; 2) allow continuous processing of nanofibers for very high surface area fibers in an economical operation; 3) provide a unique high molecular weight chitin not available from the current industrial process, leading to stronger, more durable fibers; and 4) allow easy chemical modification of the large surface areas of the fibers for appending uranyl selective functionality providing selectivity and ease of stripping. The resulting

Parenteral adjuvant potential of recombinant B subunit of Escherichia coli heat-labile enterotoxin

Directory of Open Access Journals (Sweden)

Carlos Eduardo Pouey da Cunha

Full Text Available BACKGROUND The B subunit of Escherichia coli heat-labile enterotoxin (LTB is a potent mucosal immune adjuvant. However, there is little information about LTB's potential as a parenteral adjuvant. OBJECTIVES We aimed at evaluating and better understanding rLTB's potential as a parenteral adjuvant using the fused R1 repeat of Mycoplasma hyopneumoniae P97 adhesin as an antigen to characterise the humoral immune response induced by this construct and comparing it to that generated when aluminium hydroxide is used as adjuvant instead. METHODS BALB/c mice were immunised intraperitoneally with either rLTBR1 or recombinant R1 adsorbed onto aluminium hydroxide. The levels of systemic anti-rR1 antibodies (total Ig, IgG1, IgG2a, and IgA were assessed by enzyme-linked immunosorbent assay (ELISA. The ratio of IgG1 and IgG2a was used to characterise a Th1, Th2, or mixed Th1/Th2 immune response. FINDINGS Western blot confirmed rR1, either alone or fused to LTB, remained antigenic; anti-cholera toxin ELISA confirmed that LTB retained its activity when expressed in a heterologous system. Mice immunised with the rLTBR1 fusion protein produced approximately twice as much anti-rR1 immunoglobulins as mice vaccinated with rR1 adsorbed onto aluminium hydroxide. Animals vaccinated with either rLTBR1 or rR1 adsorbed onto aluminium hydroxide presented a mixed Th1/Th2 immune response. We speculate this might be a result of rR1 immune modulation rather than adjuvant modulation. Mice immunised with rLTBR1 produced approximately 1.5-fold more serum IgA than animals immunised with rR1 and aluminium hydroxide. MAIN CONCLUSIONS The results suggest that rLTB is a more powerful parenteral adjuvant than aluminium hydroxide when administered intraperitoneally as it induced higher antibody titres. Therefore, we recommend that rLTB be considered an alternative adjuvant, even if different administration routes are employed.

Performance of an optimally contact-cooled high-heat-load mirror at the APS

International Nuclear Information System (INIS)

Cai, Z.; Khounsary, A.; Lai, B.; McNulty, I.; Yun, W.

1998-01-01

X-ray undulator beamlines at third-generation synchrotrons facilities use either a monochromator or a mirror as the first optical element. In this paper, the thermal and optical performance of an optimally designed contact-cooled high-heat-load x-ray mirror used as the first optical element on the 2ID undulator beamline at the Advanced Photon Source (APS) is reported. It is shown that this simple and economical mirror design can comfortably handle the high heat load of undulator beamlines and provide good performance with long-term reliability and ease of operation. Availability and advantages of such mirrors can make the mirror-first approach to high-heat-load beamline design an attractive alternative to monochromator-first beamlines in many circumstances

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

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Zakieh I. Al-Kurdi

2015-03-01

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

Branched chain amino acids maintain the molecular weight of poly(γ-glutamic acid) of Bacillus licheniformis ATCC 9945 during the fermentation.

Science.gov (United States)

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.

Media optimization for elevated molecular weight and mass production of pigment-free pullulan.

Science.gov (United States)

Yu, Xiaoliu; Wang, Yulei; Wei, Gongyuan; Dong, Yingying

2012-07-01

In this study, an Aureobasidium pullulans SZU 1001 mutant, deficient in pigment production, was screened by complex UV and γ-ray mutagenesis. Medium composition optimization for increased pullulan molecular weight and production was conducted using this mutant. Six nutrients: yeast extract, (NH4)2SO4, K2HPO4, NaCl, MgSO4·7H2O and CaCl2 were detected within pullulan production in flasks. It is shown that NaCl and K2HPO4 have significant influences on molecular weight of pullulan, while yeast extract and (NH4)2SO4 significantly affect pullulan yield. To achieve a higher molecular weight and more efficient pullulan production, a response surface methodology approach was introduced to predict an optimal nutrient combination. A molecular weight of 5.74 × 10(6) and pullulan yield on glucose of 51.30% were obtained under batch pullulan fermentation with the optimized media, which increased molecular weight and pullulan production by 97.25% and 11.04%, respectively compared with the control media. Copyright © 2012 Elsevier Ltd. All rights reserved.

Low molecular weight compounds as effective dispersing agents in the formation of colloidal silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Natsuki, Jun; Natsuki, Toshiaki, E-mail: natsuki@shinshu-u.ac.jp; Abe, Takao [Shinshu University, Faculty of Textile Science and Technology (Japan)

2013-03-15

A convenient method to synthesize uniform, well-dispersed colloidal silver nanoparticles is described. Aldonic acid or {alpha}-hydroxy acid compounds of low molecular weight are used instead of polymeric compounds as dispersing agents to prepare silver nanoparticles. The size, conformation, and electrical conductivity of the silver nanoparticles, and the effect and function of the dispersing agents are investigated in detail. Using these low molecular weight compounds as dispersing agents, silver nanoparticles with a diameter of 10 nm or less and high electrical conductivity can be obtained. In addition, this procedure allows silver nanoparticles to be sintered at 150 Degree-Sign C, which is lower than that required for silver nanoparticle formulation using polymeric compounds (200 Degree-Sign C). The silver nanoparticles produced by this process can be used to prepare various inks and to manufacture electronic circuits. It is found that low molecular weight compounds are more effective dispersing agents than polymeric compounds in the formation of silver nanoparticles.

Alkali-labile sites and post-irradiation effects in single-stranded DNA induced by H radicals

International Nuclear Information System (INIS)

Lafleur, M.V.M.; Heuvel, N. van; Woldhuis, J.; Loman, H.

1978-01-01

Single-stranded phiX174 DNA in aqueous solutions has been irradiated in the absence of oxygen, under conditions in which H radicals react with the DNA. It was shown that H radical reactions result in breaks, which contribute approximately 10 per cent inactivation. Further, two types of alkali-labile sites were formed. One was lethal and gave rise to single-strand breaks by alkali and was most probably identical with post-irradiation heat damage and contributed about 33 per cent to the inactivation mentioned above. The other consisted of non-lethal damage, partly dihydropyrimidine derivatives, and was converted to lethal damage by alkali. This followed from experiments in which the DNA was treated with osmium-tetroxide, which oxidized thymine to 5,6-dihydroxydihydrothymine. Treatment with alkali of this DNA gave the same temperature dependence as found for the non-lethal alkali-labile sites in irradiated DNA. A similar temperature dependence was found for dihydrothymine and irradiated pyrimidines with alkali. (author)

Poly(1,4-cyclohexanedimethylene 2,6-naphthalate polyester with high melting point: Effect of different synthesis methods on molecular weight and properties

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N. Kasmi

2018-03-01

Full Text Available In the current manuscript, a new approach for the synthesis of poly(1,4- cyclohexanedimethylene 2,6-naphthalate (PCHDMN derived from dimethyl 2,6-naphthalenedicarboxylate (2,6-DMN and 1,4-Cyclohexanedimethanol (CHDM via melt polycondensation method is introduced. The effect of three different synthesis pathways, polycondensation time and temperature on polyesters molecular weight increase has been investigated. All of the prepared samples were characterized measuring their intrinsic viscosity (IV, thermal properties and morphology with differential scanning calorimetry (DSC and wide-angle X-ray diffraction (WAXD, respectively. The results demonstrated the effectiveness of the synthesis pathway proposed for the preparation of PCHDMN, resulting in high molecular weight (IV value around 0.5 dL/g and much shorter reaction time. Melt polycondensation temperatures above melting point of polyester should be avoided to be used due to the decomposition of polyester. This was proved by thermogravimetric analysis (TGA and Pyrolysis-gas chromatography–mass spectroscopy analysis (Py-GC/MS.

Stripping of 1.04 MeV per nucleon krypton ions in high molecular weight vapours

International Nuclear Information System (INIS)

Eastham, D.A.; Joy, T.; Clark, R.B.; King, R.

1976-01-01

Equilibrium charge state distributions have been measured for 1.04 MeV per nucleon krypton ions in heavy vapours with molecular weights from 462 to 6500. Non-equilibrium data are presented for the heaviest vapour. A maximum increase of 0.8 in the mean charge is found relative to a conventional diatomic gas but the pressures required are two orders of magnitude less. (Auth.)

Repeated labilization-reconsolidation processes strengthen declarative memory in humans.

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Cecilia Forcato

Full Text Available The idea that memories are immutable after consolidation has been challenged. Several reports have shown that after the presentation of a specific reminder, reactivated old memories become labile and again susceptible to amnesic agents. Such vulnerability diminishes with the progress of time and implies a re-stabilization phase, usually referred to as reconsolidation. To date, the main findings describe the mechanisms associated with the labilization-reconsolidation process, but little is known about its functionality from a biological standpoint. Indeed, two functions have been proposed. One suggests that destabilization of the original memory after the reminder allows the integration of new information into the background of the original memory (memory updating, and the other suggests that the labilization-reconsolidation process strengthens the original memory (memory strengthening. We have previously reported the reconsolidation of human declarative memories, demonstrating memory updating in the framework of reconsolidation. Here we deal with the strengthening function attributed to the reconsolidation process. We triggered labilization-reconsolidation processes successively by repeated presentations of the proper reminder. Participants learned an association between five cue-syllables and their respective response-syllables. Twenty-four hours later, the paired-associate verbal memory was labilized by exposing the subjects to one, two or four reminders. The List-memory was evaluated on Day 3 showing that the memory was improved when at least a second reminder was presented in the time window of the first labilization-reconsolidation process prompted by the earlier reminder. However, the improvement effect was revealed on Day 3, only when at least two reminders were presented on Day 2 and not as a consequence of only retrieval. Therefore, we propose central concepts for the reconsolidation process, emphasizing its biological role and the

Repeated Labilization-Reconsolidation Processes Strengthen Declarative Memory in Humans

Science.gov (United States)

Forcato, Cecilia; Rodríguez, María L. C.; Pedreira, María E.

2011-01-01

The idea that memories are immutable after consolidation has been challenged. Several reports have shown that after the presentation of a specific reminder, reactivated old memories become labile and again susceptible to amnesic agents. Such vulnerability diminishes with the progress of time and implies a re-stabilization phase, usually referred to as reconsolidation. To date, the main findings describe the mechanisms associated with the labilization-reconsolidation process, but little is known about its functionality from a biological standpoint. Indeed, two functions have been proposed. One suggests that destabilization of the original memory after the reminder allows the integration of new information into the background of the original memory (memory updating), and the other suggests that the labilization-reconsolidation process strengthens the original memory (memory strengthening). We have previously reported the reconsolidation of human declarative memories, demonstrating memory updating in the framework of reconsolidation. Here we deal with the strengthening function attributed to the reconsolidation process. We triggered labilization-reconsolidation processes successively by repeated presentations of the proper reminder. Participants learned an association between five cue-syllables and their respective response-syllables. Twenty-four hours later, the paired-associate verbal memory was labilized by exposing the subjects to one, two or four reminders. The List-memory was evaluated on Day 3 showing that the memory was improved when at least a second reminder was presented in the time window of the first labilization-reconsolidation process prompted by the earlier reminder. However, the improvement effect was revealed on Day 3, only when at least two reminders were presented on Day2 and not as a consequence of only retrieval. Therefore, we propose central concepts for the reconsolidation process, emphasizing its biological role and the parametrical constrains

Gradient estimates on the weighted p-Laplace heat equation

Science.gov (United States)

Wang, Lin Feng

2018-01-01

In this paper, by a regularization process we derive new gradient estimates for positive solutions to the weighted p-Laplace heat equation when the m-Bakry-Émery curvature is bounded from below by -K for some constant K ≥ 0. When the potential function is constant, which reduce to the gradient estimate established by Ni and Kotschwar for positive solutions to the p-Laplace heat equation on closed manifolds with nonnegative Ricci curvature if K ↘ 0, and reduce to the Davies, Hamilton and Li-Xu's gradient estimates for positive solutions to the heat equation on closed manifolds with Ricci curvature bounded from below if p = 2.

Suppression of inflammation in a mouse model of rheumatoid arthritis using targeted lipase-labile fumagillin prodrug nanoparticles.

Science.gov (United States)

Zhou, Hui-Fang; Yan, Huimin; Senpan, Angana; Wickline, Samuel A; Pan, Dipanjan; Lanza, Gregory M; Pham, Christine T N

2012-11-01

Nanoparticle-based therapeutics are emerging technologies that have the potential to greatly impact the treatment of many human diseases. However, drug instability and premature release from the nanoparticles during circulation currently preclude clinical translation. Herein, we use a lipase-labile (Sn 2) fumagillin prodrug platform coupled with a unique lipid surface-to-surface targeted delivery mechanism, termed contact-facilitated drug delivery, to counter the premature drug release and overcome the inherent photo-instability of fumagillin, an established anti-angiogenic agent. We show that α(v)β(3)-integrin targeted fumagillin prodrug nanoparticles, administered at 0.3 mg of fumagillin prodrug/kg of body weight suppress the clinical disease indices of KRN serum-mediated arthritis in a dose-dependent manner when compared to treatment with the control nanoparticles with no drug. This study demonstrates the effectiveness of this lipase-labile prodrug nanocarrier in a relevant preclinical model that approximates human rheumatoid arthritis. The lipase-labile prodrug paradigm offers a translatable approach that is broadly applicable to many targeted nanosystems and increases the translational potential of this platform for many diseases. Copyright © 2012 Elsevier Ltd. All rights reserved.

Poly(mono/diethylene glycol n-tetradecyl ether vinyl ethers with Various Molecular Weights as Phase Change Materials

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Dongfang Pei

2018-02-01

Full Text Available At present, research on the relationship of comb-like polymer phase change material structures and their heat storage performance is scarce. Therefore, this relationship from both micro and macro perspectives will be studied in this paper. In order to achieve a high phase change enthalpy, ethylene glycol segments were introduced between the vinyl and the alkyl side chains. A series of poly(mono/diethylene glycol n-tetradecyl ether vinyl ethers (PC14EnVEs (n = 1, 2 with various molecular weights were polymerized by living cationic polymerization. The results of PC14E1VE and PC14E2VE showed that the minimum number of carbon atoms required for side-chain crystallization were 7.7 and 7.2, which were lower than that reported in the literature. The phase change enthalpy 89 J/g (for poly(mono ethylene glycol n-tetradecyl ether vinyl ethers and 86 J/g (for poly(hexadecyl acrylate were approximately equal. With the increase of molecular weight, the melting temperature, the melting enthalpy, and the initial thermal decomposition temperature of PC14E1VE changed from 27.0 to 28.0 °C, from 95 to 89 J/g, and from 264 to 287 °C, respectively. When the number average molar mass of PC14EnVEs exceeded 20,000, the enthalpy values remained basically unchanged. The introduction of the ethylene glycol chain was conducive to the crystallization of alkyl side chains.

Highly active, recyclable catalyst for the manufacture of viscous, low molecular weight, CO–ethene–propene-based polyketone, base component for a new class of resins

NARCIS (Netherlands)

Broekhuis, Antonius A.; Dirkzwager, Hendrik; Mul, Wilhelmus P.; Heeres, Hero J.; Linden, Adrianus J. van der; Orpen, A. Guy

2002-01-01

A highly active, recyclable homogeneous palladium(II) catalyst is described for the manufacture of viscous, low molecular weight CO–ethene–propene-based polyketone (Carilite Oligomer), used for the manufacture of a new class of resins (Carilite Resins). The catalyst is composed of palladium acetate,

A Tribological Assessment of Ultra High Molecular Weight Polyethylene Types GUR 1020 and GUR 1050 for Orthopedic Applications

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Benjamin J. Hunt

2016-06-01

Full Text Available The wear properties of biomaterials have been demonstrated to have a high importance within orthopedic bearing surfaces. This study performed a comparison of the wear between the two main grades of Ultra High Molecular Weight Polyethylene types GUR 1020 and GUR 1050 articulating against Cobalt Chromium. Such a high capacity wear comparison has not been reported elsewhere in the scientific literature. Under an identical testing protocol it was found that GUR 1020 had a wear factor of 3.92 ± 0.55 × 10 − 6 ( mm 3 / Nm and GUR 1050 had a wear factor of 3.64 ± 0.39 × 10 − 6 ( mm 3 / Nm , with a non-statistical significant difference of p = 0.052. These wear factors correlate closely with those observed from other screening wear studies and explant analysis.

Forecasting of heat capacity of molecular inorganic liquids

International Nuclear Information System (INIS)

Sladkov, I.B.; Neganov, O.S.

1992-01-01

On the basis of analysis of experimental material on heat capacity of liquids, covering 350 molecular inorganic compounds, atomic parts of heat capacity for 58 elements of the Periodic system were obtained. Data on the accuracy of heat capacity calculation by the Neumann-Kopp rule using the recommended atomic parts C p are presented. For the Kelli rule it is assertained that the factor of proportiomality between heat capacity and the number of atoms in compound molecule in the general case depends on the type of anion and compound coordination. The Neumann-Kopp-Kelli rules provide a satisfactory accuracy of prediction

Solid-State Polymerization of Poly(Ethylene Furanoate Biobased Polyester, II: An Efficient and Facile Method to Synthesize High Molecular Weight Polyester Appropriate for Food Packaging Applications

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Nejib Kasmi

2018-04-01

Full Text Available The goal of this study was to synthesize, through a facile strategy, high molecular weight poly(ethylene furanoate (PEF, which could be applicable in food packaging applications. The efficient method to generate PEF with high molecular weight consists of carrying out a first solid-state polycondensation under vacuum for 6 h reaction time at 205 °C for the resulting polymer from two-step melt polycondensation process, which is catalyzed by tetrabutyl titanate (TBT. A remelting step was thereafter applied for 15 min at 250 °C for the obtained polyester. Thus, the PEF sample was ground into powder, and was then crystallized for 6 h at 170 °C. This polyester is then submitted to a second solid-state polycondensation (SSP carried out at different reaction times (1, 2, 3.5, and 5 h and temperatures 190, 200, and 205 °C, under vacuum. Ultimately, a significant increase in intrinsic viscosity is observed with only 5 h reaction time at 205 °C during the second SSP being needed to obtain very high molecular weight PEF polymer greater than 1 dL/g, which sufficient for manufacturing purposes. Intrinsic viscosity (IV, carboxyl end-group content (–COOH, and thermal properties, via differential scanning calorimetry (DSC, were measured for all resultant polyesters. Thanks to the post-polymerization process, DSC results showed that the melting temperatures of the prepared PEF samples were steadily enhanced in an obvious way as a function of reaction time and temperature increase. It was revealed, as was expected for all SSP samples, that the intrinsic viscosity and the average molecular weight of PEF polyester increased with increasing SSP time and temperature, whereas the number of carboxyl end-group concentration was decreased. A simple kinetic model was also developed and used to predict the time evolution of polyesters IV, as well as the carboxyl and hydroxyl end-groups of PEF during the SSP.

Molecular wires acting as quantum heat ratchets

OpenAIRE

Zhan, Fei; Li, Nianbei; Kohler, Sigmund; Hänggi, Peter

2009-01-01

We explore heat transfer in molecular junctions between two leads in the absence of a finite net thermal bias. The application of an unbiased, time-periodic temperature modulation of the leads entails a dynamical breaking of reflection symmetry, such that a directed heat current may emerge (ratchet effect). In particular, we consider two cases of adiabatically slow driving, namely (i) periodic temperature modulation of only one lead and (ii) temperature modulation of both leads with an ac dri...

Construction of hierarchically porous metal-organic frameworks through linker labilization

Science.gov (United States)

Yuan, Shuai; Zou, Lanfang; Qin, Jun-Sheng; Li, Jialuo; Huang, Lan; Feng, Liang; Wang, Xuan; Bosch, Mathieu; Alsalme, Ali; Cagin, Tahir; Zhou, Hong-Cai

2017-05-01

A major goal of metal-organic framework (MOF) research is the expansion of pore size and volume. Although many approaches have been attempted to increase the pore size of MOF materials, it is still a challenge to construct MOFs with precisely customized pore apertures for specific applications. Herein, we present a new method, namely linker labilization, to increase the MOF porosity and pore size, giving rise to hierarchical-pore architectures. Microporous MOFs with robust metal nodes and pro-labile linkers were initially synthesized. The mesopores were subsequently created as crystal defects through the splitting of a pro-labile-linker and the removal of the linker fragments by acid treatment. We demonstrate that linker labilization method can create controllable hierarchical porous structures in stable MOFs, which facilitates the diffusion and adsorption process of guest molecules to improve the performances of MOFs in adsorption and catalysis.

Ubiquitous water-soluble molecules in aquatic plant exudates determine specific insect attraction.

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Julien Sérandour

Full Text Available Plants produce semio-chemicals that directly influence insect attraction and/or repulsion. Generally, this attraction is closely associated with herbivory and has been studied mainly under atmospheric conditions. On the other hand, the relationship between aquatic plants and insects has been little studied. To determine whether the roots of aquatic macrophytes release attractive chemical mixtures into the water, we studied the behaviour of mosquito larvae using olfactory experiments with root exudates. After testing the attraction on Culex and Aedes mosquito larvae, we chose to work with Coquillettidia species, which have a complex behaviour in nature and need to be attached to plant roots in order to obtain oxygen. This relationship is non-destructive and can be described as commensal behaviour. Commonly found compounds seemed to be involved in insect attraction since root exudates from different plants were all attractive. Moreover, chemical analysis allowed us to identify a certain number of commonly found, highly water-soluble, low-molecular-weight compounds, several of which (glycerol, uracil, thymine, uridine, thymidine were able to induce attraction when tested individually but at concentrations substantially higher than those found in nature. However, our principal findings demonstrated that these compounds appeared to act synergistically, since a mixture of these five compounds attracted larvae at natural concentrations (0.7 nM glycerol, <0.5 nM uracil, 0.6 nM thymine, 2.8 nM uridine, 86 nM thymidine, much lower than those found for each compound tested individually. These results provide strong evidence that a mixture of polyols (glycerol, pyrimidines (uracil, thymine, and nucleosides (uridine, thymidine functions as an efficient attractive signal in nature for Coquillettidia larvae. We therefore show for the first time, that such commonly found compounds may play an important role in plant-insect relationships in aquatic eco-systems.

Effects of EDTA and low molecular weight organic acids on soil solution properties of a heavy metal polluted soil.

Science.gov (United States)

Wu, L H; Luo, Y M; Christie, P; Wong, M H

2003-02-01

A pot experiment was conducted to study the effects of EDTA and low molecular weight organic acids (LMWOA) on the pH, total organic carbon (TOC) and heavy metals in the soil solution in the rhizosphere of Brassica juncea grown in a paddy soil contaminated with Cu, Zn, Pb and Cd. The results show that EDTA and LMWOA have no effect on the soil solution pH. EDTA addition significantly increased the TOC concentrations in the soil solution. The TOC concentrations in treatments with EDTA were significantly higher than those in treatments with LMWOA. Adding 3 mmol kg(-1) EDTA to the soil markedly increased the total concentrations of Cu, Zn, Pb and Cd in the soil solution. Compared to EDTA, LMWOA had a very small effect on the metal concentrations. Total concentrations in the soil solution followed the sequence: EDTA > citric acid (CA) approximately oxalic acid (OA) approximately malic acid (MA) for Cu and Pb; EDTA > MA > CA approximately OA for Zn; and EDTA > MA > CA > OA for Cd. The labile concentrations of Cu, Zn, Pb and Cd showed similar trends to the total concentrations.

Circulating antibodies to inducible heat shock protein 70 in patients with uveitis

NARCIS (Netherlands)

de Smet, M. D.; Ramadan, A.

2001-01-01

Heat shock proteins with molecular weight 70 kDa (hsp70) are highly conserved immunogenic intracellular molecules. There are two main subtypes: one is expressed constitutively (hsc70), while the other is induced under stressful conditions (ihsp70). Using an ELISA directed against recombinant human

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

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Faezeh Moghadam Ariaee

2016-10-01

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

Heat Shock Proteins in Tendinopathy: Novel Molecular Regulators

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Neal L. Millar

2012-01-01

Full Text Available Tendon disorders—tendinopathies—are the primary reason for musculoskeletal consultation in primary care and account for up to 30% of rheumatological consultations. Whilst the molecular pathophysiology of tendinopathy remains difficult to interpret the disease process involving repetitive stress, and cellular load provides important mechanistic insight into the area of heat shock proteins which spans many disease processes in the autoimmune community. Heat shock proteins, also called damage-associated molecular patterns (DAMPs, are rapidly released following nonprogrammed cell death, are key effectors of the innate immune system, and critically restore homeostasis by promoting the reconstruction of the effected tissue. Our investigations have highlighted a key role for HSPs in tendion disease which may ultimately affect tissue rescue mechanisms in tendon pathology. This paper aims to provide an overview of the biology of heat shock proteins in soft tissue and how these mediators may be important regulators of inflammatory mediators and matrix regulation in tendinopathy.

Separation of mouse testis cells on a Celsep (TM) apparatus and their usefulness as a source of high molecular weight DNA or RNA

Science.gov (United States)

Wolgemuth, D. J.; Gizang-Ginsberg, E.; Engelmyer, E.; Gavin, B. J.; Ponzetto, C.

1985-01-01

The use of a self-contained unit-gravity cell separation apparatus for separation of populations of mouse testicular cells is described. The apparatus, a Celsep (TM), maximizes the unit area over which sedimentation occurs, reduces the amount of separation medium employed, and is quite reproducible. Cells thus isolated have been good sources for isolation of DNA, and notably, high molecular weight RNA.

High Molecular Weight Adiponectin Levels are Neither Influenced by Adiponectin Polymorphisms Nor Associated with Insulin Resistance in Mixed-Ancestry Hyperglycemic Subjects from South Africa

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Zemlin Annalise E

2016-10-01

Full Text Available Background: High molecular weight (HMW adiponectin has antiatherogenic, antiinflammatory and antidiabetic properties and these effects have been linked to its effect on high density lipoprotein cholesterol (HDL-c. Single nucleotide polymorphisms (SNPs in the adiponectin gene influence adiponectin levels. We examined the relationship between HMW-adiponectin levels and cardiometabolic traits in normo- and hyperglycemic mixed ancestry South Africans and correlated these levels to two common polymorphisms.

Fate and lability of silver in soils: Effect of ageing

Science.gov (United States)

The fate and lability of added soluble Ag in soils over time was examined by measurement of labile metal (E-value) by isotopic dilution using the 110mAg radioactive isotope and the solid-phase speciation of Ag by X-ray absorption near edge structure (XANES) spectrosco...

Risk organ preservation technique in reirradiation. Injection of native type high molecular weight hyaluronate

International Nuclear Information System (INIS)

Kishi, Kazushi; Noda, Yasutaka; Tanaka, Kayo

2012-01-01

We developed a practical method of brachytherapy effective for reirradiation, using hyaluronate gel injection to separate the target to be intensively. We intended curative reirradiation with preserving organs at risk. Native-type high molecular weight hyaluronate that has an ideal biologic property to reduce inflammation via inhibitory activity to CD44 and other inflammation receptors was injected to create space during radiotherapy. Rectum, small intestines, skin, and various normal organs are effectively separated and thus eradicative re-irradiation was carried out in safe. We reviewed 55 patients who required the method. There were no complications related to the procedure. Prescribed dose to 100% of the planning target volume (PTV) was 77.93 Gy (range 54-92) equivalent at alpha/beta ratio of 3, with much higher subvolume effect, and the saving effects were enhanced at 3.35 times in the average of those without gel injection. In conclusion, the interventional brachytherapy with hyaluronate gel injection provided 3.35 times safer dose-escalated and eradicative treatment in reirradiation. (author)

High-affinity binding of two molecules of cysteine proteinases to low-molecular-weight kininogen.

Science.gov (United States)

Turk, B.; Stoka, V.; Björk, I.; Boudier, C.; Johansson, G.; Dolenc, I.; Colic, A.; Bieth, J. G.; Turk, V.

1995-01-01

Human low-molecular-weight kininogen (LK) was shown by fluorescence titration to bind two molecules of cathepsins L and S and papain with high affinity. By contrast, binding of a second molecule of cathepsin H was much weaker. The 2:1 binding stoichiometry was confirmed by titration monitored by loss of enzyme activity and by sedimentation velocity experiments. The kinetics of binding of cathepsins L and S and papain showed the two proteinase binding sites to have association rate constants kass,1 = 10.7-24.5 x 10(6) M-1 s-1 and kass,2 = 0.83-1.4 x 10(6) M-1 s-1. Comparison of these kinetic constants with previous data for intact LK and its separated domains indicate that the faster-binding site is also the tighter-binding site and is present on domain 3, whereas the slower-binding, lower-affinity site is on domain 2. These results also indicate that there is no appreciable steric hindrance for the binding of proteinases between the two binding sites or from the kininogen light chain. PMID:8528085

Mucin Agarose Gel Electrophoresis: Western Blotting for High-molecular-weight Glycoproteins.

Science.gov (United States)

Ramsey, Kathryn A; Rushton, Zachary L; Ehre, Camille

2016-06-14

Mucins, the heavily-glycosylated proteins lining mucosal surfaces, have evolved as a key component of innate defense by protecting the epithelium against invading pathogens. The main role of these macromolecules is to facilitate particle trapping and clearance while promoting lubrication of the mucosa. During protein synthesis, mucins undergo intense O-glycosylation and multimerization, which dramatically increase the mass and size of these molecules. These post-translational modifications are critical for the viscoelastic properties of mucus. As a result of the complex biochemical and biophysical nature of these molecules, working with mucins provides many challenges that cannot be overcome by conventional protein analysis methods. For instance, their high-molecular-weight prevents electrophoretic migration via regular polyacrylamide gels and their sticky nature causes adhesion to experimental tubing. However, investigating the role of mucins in health (e.g., maintaining mucosal integrity) and disease (e.g., hyperconcentration, mucostasis, cancer) has recently gained interest and mucins are being investigated as a therapeutic target. A better understanding of the production and function of mucin macromolecules may lead to novel pharmaceutical approaches, e.g., inhibitors of mucin granule exocytosis and/or mucolytic agents. Therefore, consistent and reliable protocols to investigate mucin biology are critical for scientific advancement. Here, we describe conventional methods to separate mucin macromolecules by electrophoresis using an agarose gel, transfer protein into nitrocellulose membrane, and detect signal with mucin-specific antibodies as well as infrared fluorescent gel reader. These techniques are widely applicable to determine mucin quantitation, multimerization and to test the effects of pharmacological compounds on mucins.

Weight Optimization of Active Thermal Management Using a Novel Heat Pump

Science.gov (United States)

Lear, William E.; Sherif, S. A.

2004-01-01

Efficient lightweight power generation and thermal management are two important aspects for space applications. Weight is added to the space platforms due to the inherent weight of the onboard power generation equipment and the additional weight of the required thermal management systems. Thermal management of spacecraft relies on rejection of heat via radiation, a process that can result in large radiator mass, depending upon the heat rejection temperature. For some missions, it is advantageous to incorporate an active thermal management system, allowing the heat rejection temperature to be greater than the load temperature. This allows a reduction of radiator mass at the expense of additional system complexity. A particular type of active thermal management system is based on a thermodynamic cycle, developed by the authors, called the Solar Integrated Thermal Management and Power (SITMAP) cycle. This system has been a focus of the authors research program in the recent past (see Fig. 1). One implementation of the system requires no moving parts, which decreases the vibration level and enhances reliability. Compression of the refrigerant working fluid is accomplished in this scheme via an ejector.

MALDI matrices for low molecular weight compounds: an endless story?

Science.gov (United States)

Calvano, Cosima Damiana; Monopoli, Antonio; Cataldi, Tommaso R I; Palmisano, Francesco

2018-04-23

Since its introduction in the 1980s, matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) has gained a prominent role in the analysis of high molecular weight biomolecules such as proteins, peptides, oligonucleotides, and polysaccharides. Its application to low molecular weight compounds has remained for long time challenging due to the spectral interferences produced by conventional organic matrices in the low m/z window. To overcome this problem, specific sample preparation such as analyte/matrix derivatization, addition of dopants, or sophisticated deposition technique especially useful for imaging experiments, have been proposed. Alternative approaches based on second generation (rationally designed) organic matrices, ionic liquids, and inorganic matrices, including metallic nanoparticles, have been the object of intense and continuous research efforts. Definite evidences are now provided that MALDI MS represents a powerful and invaluable analytical tool also for small molecules, including their quantification, thus opening new, exciting applications in metabolomics and imaging mass spectrometry. This review is intended to offer a concise critical overview of the most recent achievements about MALDI matrices capable of specifically address the challenging issue of small molecules analysis. Graphical abstract An ideal Book of matrices for MALDI MS of small molecules.

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

Science.gov (United States)

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

2018-01-01

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

Synthesis and reforming of high molecular-weigth compounds by the utilization of radiation

International Nuclear Information System (INIS)

Machi, Sueo

1976-01-01

Radiation effects on the synthesis are reforming of high molecular-weight compounds are reviewed. The report is divided into four main parts. The first part deals with the characteristics of the radiation processing. The reaction can be started in a wide range of temperature including very low temperature. Catalysts are unnecessary. The reaction velocity is fast, and the reaction in solid phase can be started uniformly. And the quality of products is well controllable. The second part deals with the synthesis of high molecular-weight compounds by radiation polymerization. Radical polymerization and ionizing polymerization, gas phase and liquid phase polymerization, the polymerization and copolymerization of fluorine-containing monomers, and solid phase polymerization and low temperature polymerization are included in this part. Attention is directed to the continuous production system for the radiation polymerization of ethylene developed by Japan Atomic Energy Research Institute. The third part deals with the reforming of high molecular-weight compounds by radiation graft polymerization. The combination of backbone polymers and monomers for reforming plastics and fibers, the membranes for reverse osmosis, porous membranes, and ion exchange membranes are included. The fourth part deals with the reforming of high molecular-weight compounds by the cross-linking. Polyethylene, PVC, ethyl acrylate copolymer and the like are included. (Iwakiri, K.)

Ingestion of High Molecular Weight Carbohydrate Enhances Subsequent Repeated Maximal Power: A Randomized Controlled Trial.

Directory of Open Access Journals (Sweden)

Jonathan M Oliver

Full Text Available Athletes in sports demanding repeat maximal work outputs frequently train concurrently utilizing sequential bouts of intense endurance and resistance training sessions. On a daily basis, maximal work within subsequent bouts may be limited by muscle glycogen availability. Recently, the ingestion of a unique high molecular weight (HMW carbohydrate was found to increase glycogen re-synthesis rate and enhance work output during subsequent endurance exercise, relative to low molecular weight (LMW carbohydrate ingestion. The effect of the HMW carbohydrate, however, on the performance of intense resistance exercise following prolonged-intense endurance training is unknown. Sixteen resistance trained men (23±3 years; 176.7±9.8 cm; 88.2±8.6 kg participated in a double-blind, placebo-controlled, randomized 3-way crossover design comprising a muscle-glycogen depleting cycling exercise followed by ingestion of placebo (PLA, or 1.2 g•kg•bw-1 of LMW or HMW carbohydrate solution (10% with blood sampling for 2-h post-ingestion. Thereafter, participants performed 5 sets of 10 maximal explosive repetitions of back squat (75% of 1RM. Compared to PLA, ingestion of HMW (4.9%, 90%CI 3.8%, 5.9% and LMW (1.9%, 90%CI 0.8%, 3.0% carbohydrate solutions substantially increased power output during resistance exercise, with the 3.1% (90% CI 4.3, 2.0% almost certain additional gain in power after HMW-LMW ingestion attributed to higher movement velocity after force kinematic analysis (HMW-LMW 2.5%, 90%CI 1.4, 3.7%. Both carbohydrate solutions increased post-exercise plasma glucose, glucoregulatory and gut hormones compared to PLA, but differences between carbohydrates were unclear; thus, the underlying mechanism remains to be elucidated. Ingestion of a HMW carbohydrate following prolonged intense endurance exercise provides superior benefits to movement velocity and power output during subsequent repeated maximal explosive resistance exercise. This study was registered

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

Science.gov (United States)

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

2017-06-01

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

Fabrication, Physicochemical Characterization, and Performance Evaluation of Biodegradable Polymeric Microneedle Patch System for Enhanced Transcutaneous Flux of High Molecular Weight Therapeutics.

Science.gov (United States)

Shah, Viral; Choudhury, Bijaya Krushna

2017-11-01

A revolutionary paradigm shift is being observed currently, towards the use of therapeutic biologics for disease management. The present research was focused on designing an efficient dosage form for transdermal delivery of α-choriogonadotropin (high molecular weight biologic), through biodegradable polymeric microneedles. Polyvinylpyrrolidone-based biodegradable microneedle arrays loaded with high molecular weight polypeptide, α-choriogonadotropin, were fabricated for its systemic delivery via transdermal route. Varied process and formulation parameters were optimized for fabricating microneedle array, which in turn was expected to temporally rupture the stratum corneum layer of the skin, acting as a major barrier to drug delivery through transdermal route. The developed polymeric microneedles were optimized on the basis of quality attributes like mechanical strength, axial strength, insertion ratio, and insertion force analysis. The optimized polymeric microneedle arrays were characterized for in vitro drug release studies, ex vivo drug permeation studies, skin resealing studies, and in vivo pharmacokinetic studies. Results depicted that fabricated polymeric microneedle arrays with mechanical strength of above 5 N and good insertion ratio exhibited similar systemic bioavailability of α-choriogonadotropin in comparison to marketed subcutaneous injection formulation of α-choriogonadotropin. Thus, it was ultimately concluded that the designed drug delivery system can serve as an efficient tool for systemic delivery of therapeutic biologics, with an added benefit of overcoming the limitations of parenteral delivery, achieving better patient acceptability and compliance.

The relationship between seminal plasma zinc levels and high molecular weight zinc binding protein and sperm motility in Iraqi infertile men

International Nuclear Information System (INIS)

AbdulRasheed, Omar F

2009-01-01

To evaluate the relationship between sperm motility and total seminal plasma zinc concentration and high molecular weight zinc bound protein values in infertile Iraqi men. A case-control study was conducted at the Chemistry and Biochemistry Department, College of Medicine, Al-Nahrain University, Baghdad, Iraq between March 2005 to February 2006. The subjects for the study included 60 infertile male patients who were recruited Al-Kadhimiya Teaching Hospital, and Institute of Embryo Research and Infertility Treatment, Baghdad, Iraq. They were categorized according to their seminal parameters to oligozoospermia (n=32), azoospermia (n=22), and asthenozoospermia (n=6). Thirty nine fertile men (age range 31.87 +/- 3.76 years) were selected as controls, whose partners had conceived within the last year before participation with this study, and having normal spermiogram parameters. Seminal plasma zinc concentration and high molecular weight zinc binding proteins (HMW-Zn) were assayed in the ejaculates of fertile and infertile men. The seminal plasma zinc levels were 181.92 +/- 23.40 ug/mL in the oligozoospermia group, 178.50 +/- 18.61 ug/mL in the azoospermia group, 195.33 +/- 13.00 ug/mL in the asthenozoospermia group, and 184.66 +/- 21.31 ug/mL in the control group. The HMW-Zn% is a good index of sperm function rather than the total seminal plasma zinc levels. (author)

Practical Application of Aptamer-Based Biosensors in Detection of Low Molecular Weight Pollutants in Water Sources

Directory of Open Access Journals (Sweden)

Wei Zhang

2018-02-01

Full Text Available Water pollution has become one of the leading causes of human health problems. Low molecular weight pollutants, even at trace concentrations in water sources, have aroused global attention due to their toxicity after long-time exposure. There is an increased demand for appropriate methods to detect these pollutants in aquatic systems. Aptamers, single-stranded DNA or RNA, have high affinity and specificity to each of their target molecule, similar to antigen-antibody interaction. Aptamers can be selected using a method called Systematic Evolution of Ligands by EXponential enrichment (SELEX. Recent years we have witnessed great progress in developing aptamer selection and aptamer-based sensors for low molecular weight pollutants in water sources, such as tap water, seawater, lake water, river water, as well as wastewater and its effluents. This review provides an overview of aptamer-based methods as a novel approach for detecting low molecular weight pollutants in water sources.

Low-molecular-weight chitosans: Preparation and characterization

Czech Academy of Sciences Publication Activity Database

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

2011-01-01

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

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

DEFF Research Database (Denmark)

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

2015-01-01

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

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

Science.gov (United States)

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

Three-site mechanism and molecular weight: Time dependency in liquid propylene batch polymerization using a MgCl2-supported Ziegler-Natta catalyst

NARCIS (Netherlands)

Shimizu, Fumihiko; Pater, J.T.M.; Weickert, G.

2001-01-01

This article demonstrates that the molecular weight of propylene homopolymer decreases with time, and that the molecular weight distribution (MWD) narrows when a highly active MgCl2-supported catalyst is used in a liquid pool polymerization at constant H2 concentration and temperature. To track the

Low-molecular-weight heparins: pharmacologic profile and product differentiation.

Science.gov (United States)

Fareed, J; Jeske, W; Hoppensteadt, D; Clarizio, R; Walenga, J M

1998-09-10

The interchangeability of low-molecular-weight heparins (LMWHs) has been the subject of discussion since these products were first introduced for the prophylaxis of deep vein thrombosis. Experimental evidence now exists to show that LMWHs differ from each other in a number of characteristics. Products have been differentiated on the basis of molecular weight and biologic properties, but only limited information derived from the clinical setting is available. Potency has been described on the basis of anti-Factor Xa activity, but at equivalent anti-Xa activities, the anti-Factor IIa activity of different products shows marked variations. At the relatively small doses used for the management of postsurgical deep vein thrombosis, the effect of these interproduct differences may be relatively minor, but as LMWHs are developed for therapeutic use at much higher doses, such differences may become clinically important. Variations in safety and efficacy reported in clinical trials of LMWHs may reflect the known differences in their molecular composition and pharmacologic properties.

Ultra-High Molecular Weight Polyethylene: Influence of the Chemical, Physical and Mechanical Properties on the Wear Behavior. A Review

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Pierangiola Bracco

2017-07-01

Full Text Available Ultra-high molecular weight polyethylene (UHMWPE is the most common bearing material in total joint arthroplasty due to its unique combination of superior mechanical properties and wear resistance over other polymers. A great deal of research in recent decades has focused on further improving its performances, in order to provide durable implants in young and active patients. From “historical”, gamma-air sterilized polyethylenes, to the so-called first and second generation of highly crosslinked materials, a variety of different formulations have progressively appeared in the market. This paper reviews the structure–properties relationship of these materials, with a particular emphasis on the in vitro and in vivo wear performances, through an analysis of the existing literature.

Low Molecular Weight Heparin Improves Endothelial Function in Pregnant Women at High Risk of Preeclampsia.

Science.gov (United States)

McLaughlin, Kelsey; Baczyk, Dora; Potts, Audrey; Hladunewich, Michelle; Parker, John D; Kingdom, John C P

2017-01-01

Low molecular weight heparin (LMWH) has been investigated for the prevention of severe preeclampsia, although the mechanisms of action are unknown. The objective of this study was to investigate the cardiovascular effects of LMWH in pregnant women at high risk of preeclampsia. Pregnant women at high risk of preeclampsia (n=25) and low-risk pregnant controls (n=20) at 22 to 26 weeks' gestation underwent baseline cardiovascular assessments. High-risk women were then randomized to LMWH or saline placebo (30 mg IV bolus and 1 mg/kg subcutaneous dose). Cardiovascular function was assessed 1 and 3 hours post randomization. The in vitro endothelial effects of patient serum and exogenous LMWH on human umbilical venous endothelial cells were determined. High-risk women demonstrated a reduced cardiac output, high resistance hemodynamic profile with impaired radial artery flow-mediated dilation compared with controls. LMWH increased flow-mediated dilation in high-risk women 3 hours after randomization compared with baseline and increased plasma levels of placental growth factor, soluble fms-like tyrosine kinase-1, and myeloperoxidase. Serum from high-risk women impaired endothelial cell angiogenesis and increased PlGF-1 and PlGF-2 transcription compared with serum from low-risk controls. Coexposure of high-risk serum with LMWH improved the in vitro angiogenic response such that it was equivalent to that of low-risk serum and promoted placental growth factor secretion. LMWH improves maternal endothelial function in pregnant women at high risk of developing preeclampsia, possibly mediated through increased placental growth factor bioavailability. © 2016 American Heart Association, Inc.

Assessing soil carbon lability by near infrared spectroscopy and NaOCL oxidation

DEFF Research Database (Denmark)

Thomsen, Ingrid Kaag; Bruun, Sander; Jensen, Lars Stoumann

2009-01-01

The feasibility of near infrared (NIR) spectroscopy for quantifying labile organic matter (OM) in arable soils and for predicting soil refractory OM fractions was tested on 37 soils varying in texture and soil carbon (C) content. Three sets of arable soils (0-20 cm depth) were sampled from 1) long......-term field experiments with different OM inputs, 2) individual sites with inherent with-in field gradients in soil texture and/or C content, and 3) from a range of different sites covering variations in management and geological origin. The labile OM fraction was defined by the CO2 evolved from the soils...... incubated for 34 weeks while refractory OM was obtained by NaOCl oxidation. The labile fraction of the soil C accounted for 2-12% of the total soil C content. No systematic relationship between labile C content and total soil C or clay was found, but NIR spectra could be correlated well with the labile C...

The role of attractiveness and aggression in high school popularity

NARCIS (Netherlands)

Borch, C.; Hyde, A.; Cillessen, A.H.N.

2011-01-01

This study examines the effects of physical attractiveness and aggression on popularity among high school students. Previous work has found positive relationships between aggression and popularity and physical attractiveness and popularity. The current study goes beyond this work by examining the

Formation and stability of .beta.-structure in biodegradable ultra-high-molecular-weight poly(3-hydroxybutyrate) by infrared, Raman, and quantum chemical calculation studies

Czech Academy of Sciences Publication Activity Database

Murakami, R.; Sato, H.; Dybal, Jiří; Iwata, T.; Ozaki, Y.

2007-01-01

Roč. 48, č. 9 (2007), s. 2672-2680 ISSN 0032-3861 R&D Projects: GA ČR GA203/05/0425 Grant - others:Ministry of Education, Culture, Sports, Science and Technology(JP) 18750107 Institutional research plan: CEZ:AV0Z40500505 Keywords : ultra-high-molecular-weight poly(hydroxybutyrate) * .beta.-form * Raman spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.065, year: 2007

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

Science.gov (United States)

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.

Effects of molecular weight of natural organic matter on cadmium mobility in soil environments and its carbon isotope characteristics

International Nuclear Information System (INIS)

Mahara, Y.; Kubota, T.; Wakayama, R.; Nakano-Ohta, T.; Nakamura, T.

2007-01-01

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 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 (δ 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 ( 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

The validity of sedimentation data from high molecular weight DNA and the effects of additives on radiation-induced single-strand breakage

International Nuclear Information System (INIS)

Dugle, D.L.

1979-10-01

The optimization of many of the factors governing reproducible sedimentation behaviour of high molecular weight single-strand DNA in a particular alkaline sucrose density gradient system is described. A range of angular momenta is defined for which a constant strand breakage efficiency is required, despite a rotor speed effect which increases the measured molecular weights at decreasing rotor speeds for larger DNA molecules. The possibility is discussed that the bimodal control DNA profiles obtained after sedimentation at 11 500 rev/min (12 400 g) or less represent structural subunits of the chromatid. The random induction of single-strand DNA breaks by ionizing radiation is demonstrated by the computer-derived fits to the experimental profiles. The enhancement of single-strand break (SSB) yields in hypoxic cells by oxygen, para-nitroacetophenone (PNAP), or any of the three nitrofuran derivatives used was well correlated with increased cell killing. Furthermore, reductions in SSB yields for known hydroxyl radical (OH.) scavengers correlates with the reactivities of these compounds toward OH.. This supports the contention that some type of OH.-induced initial lesion, which may ultimately be expressed as an unrepaired or misrepaired double-strand break, constitutes a lethal event. (author)

New titanium and titanium/hydroxyapatite coatings on ultra-high-molecular-weight polyethylene-in vitro osteoblastic performance

International Nuclear Information System (INIS)

Silva, M A; Lopes, M A; Santos, J D; Fernandes, M H; Gomes, P S; Vila, M; Silva, R F

2010-01-01

The development of optimized hip joint materials is one of the most challenging opportunities in prosthetic technologies. In current approaches, ultra-high-molecular-weight polyethylene (UHMWPE) has been a favorite material for the acetabular component and, regarding the cementless technique, several coating options may be considered to contain and stabilize bearing surfaces and establish an improved interface with bone. In this work, newly developed constructs of UHMWPE coated with either commercially pure titanium (cpTi-UHMWPE), by DC magnetron sputtering, or with commercially pure titanium and hydroxyapatite (cpTi/HA-UHMWPE), by DC/RF magnetron co-sputtering, have been prepared and biologically characterized with human bone marrow-derived osteoblastic cultures. The cpTi-UHMWPE samples allowed a high cell growth and the expression of the complete osteoblastic phenotype, with high alkaline phosphatase activity, expression of osteogenic-associated genes and evident cell-mediated mineralization of the extracellular matrix. In comparison, the cpTi/HA-UHMWPE samples reported lower cell proliferation but earlier cell-mediated matrix mineralization. Accordingly, these newly developed systems may be suitable candidates to improve the osteointegration process in arthroplastic devices; nevertheless, further biological evaluation should be conducted.

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

Energy Technology Data Exchange (ETDEWEB)

Zhao, Ningbo, E-mail: curl-zhao@163.com; Wang, Xin, E-mail: 394041230@qq.com; Qin, Lei, E-mail: qinlei30@126.com; Guo, Zhengze, E-mail: zhzeguo@163.com; Li, Dehua, E-mail: lidehuafmmu@163.com

2015-09-25

Hyaluronan (HA), the simplest glycosaminoglycan and a major component of the extracellular matrix, exists in various tissues. It is involved in some critical biological procedures, including cellular signaling, cell adhesion and proliferation, and cell differentiation. The effect of molecular weight (MW) and concentration of HA on cell proliferation and differentiation was controversial. In this study, we investigated the effect of MW and concentration of HA on the proliferation and osteogenic differentiation of rabbit bone marrow-derived stem cells in vitro. Results showed that high MW HA decreased the cell adhesion rate in a concentration-dependant manner. The cell adhesion rate was decreased by increasing MW of HA. Cell proliferation was significantly enhanced by low MW HA (P < 0.05). The factorial analysis indicated that MW and concentration had an interactive effect on the cell adhesion rate and cell proliferation (P < 0.05). High MW HA increased the mRNA expressions of ALP, RUNX-2 and OCN. The higher the MW was, the higher the mRNA expressions were. The factorial analysis indicated that MW and concentration had an interactive effect on ALP mRNA expression (P < 0.05). HA of higher MW and higher concentration promoted bone formation. These findings provide some useful information in understanding the mechanism underlying the effect of MW and concentration of HA on cell proliferation and differentiation. - Highlights: • Effect of hyaluronan on cell proliferation and differentiation is evaluated in vitro. • Hyaluronan of low molecular weight increases cell proliferation. • Hyaluronan of high molecular weight promotes cell osteogenic differentiation. • Molecular weight and concentration of hyaluronan show interactive effect.

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

Directory of Open Access Journals (Sweden)

Natalie Heffernan

2015-01-01

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

Relationship between Oversulfation and Conformation of Low and High Molecular Weight Fucoidans and Evaluation of Their in Vitro Anticancer Activity

Directory of Open Access Journals (Sweden)

Myoung Lae Cho

2010-12-01

Full Text Available Low and high molecular weight fucoidans (F5-30K and F>30K were chemically modified through the addition of sulfate groups, and the effect of oversulfation on the in vitro anticancer activity was investigated. After the addition of sulfate groups, a considerable increase of 35.5 to 56.8% was observed in the sulfate content of the F5-30K fraction, while the sulfate content of the F>30K fraction increased to a lesser extent (from 31.7 to 41.2%. Significant differences in anticancer activity were observed between the oversulfated F5–30K and F>30K fractions, with activities of 37.3–68.0% and 20.6–35.8%, respectively. This variation in the anticancer activity of oversulfated fucoidan derivatives was likely due to differences in their sulfate content. The results suggest that the molecular conformation of these molecules is closely related to the extent of sulfation in the fucan backbones and that the sulfates are preferably substituted when the fucoidan polymers are in a loose molecular conformation.

Molecular wires acting as quantum heat ratchets.

Science.gov (United States)

Zhan, Fei; Li, Nianbei; Kohler, Sigmund; Hänggi, Peter

2009-12-01

We explore heat transfer in molecular junctions between two leads in the absence of a finite net thermal bias. The application of an unbiased time-periodic temperature modulation of the leads entails a dynamical breaking of reflection symmetry, such that a directed heat current may emerge (ratchet effect). In particular, we consider two cases of adiabatically slow driving, namely, (i) periodic temperature modulation of only one lead and (ii) temperature modulation of both leads with an ac driving that contains a second harmonic, thus, generating harmonic mixing. Both scenarios yield sizable directed heat currents, which should be detectable with present techniques. Adding a static thermal bias allows one to compute the heat current-thermal load characteristics, which includes the ratchet effect of negative thermal bias with positive-valued heat flow against the thermal bias, up to the thermal stop load. The ratchet heat flow in turn generates also an electric current. An applied electric stop voltage, yielding effective zero electric current flow, then mimics a solely heat-ratchet-induced thermopower ("ratchet Seebeck effect"), although no net thermal bias is acting. Moreover, we find that the relative phase between the two harmonics in scenario (ii) enables steering the net heat current into a direction of choice.

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-12-15

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

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

African Journals Online (AJOL)

Tropical Journal of Pharmaceutical Research August 2016; 15 (8): 1787-1792 ... Keywords: Acute pancreatitis, Low-molecular-weight heparin, Multiple organ function syndrome,. APACHE II score ... mediators by lowering the expression of.

Effects of Hofmeister Anions on the LCST of PNIPAM as a Function of Molecular Weight

Science.gov (United States)

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

High-latitude molecular clouds and infrared cirrus

International Nuclear Information System (INIS)

Vries, H.W. de.

1988-01-01

The high-latitude infrared cirrus detected by IRAS is identified with atomic and molecular clouds. These clouds are small (usually less than 1 sq. deg.) and show weak CO emission. On the basis of a distance of 100 pc they are characterized by a mass of a few solar masses and a radius of about 1 pc. Thermal radiation by dust as a results of heating by the diffuse interstellar radiation field is the most-plausible origin of the cirrus emission at far-infrared wavelengths. On the basis of plausible assumptions regarding the uniformity of both the gas-to-dust ratio and the heating and cooling of the dust, the flux density at 100 μm from regions with low visual extinction should be a good tracer of the gas column density. Indeed, the data show an approximately linear proportionality between N(HI), obtained from 21-cm observations, and I 100 (HI), the flux density from dust associated with HI. If the ratio of column density to flux density in high-latitude molecular clouds is equal to the corresponding relation in atomic ones, a value for the ratio of H 2 column density to CO velocity-integrated radiation temperature may be obtained. Although low-mass clouds may be large in number, the fraction of the Galactic molecular mass in the form of these clouds is probably no more than 1%

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

Science.gov (United States)

Remucal, Christina K; Cory, Rose M; Sander, Michael; McNeill, Kristopher

2012-09-04

Suwannee River fulvic acid (SRFA) was dialyzed through a 100-500 molecular weight cutoff dialysis membrane, and the dialysate and retentate were analyzed by UV-visible absorption and high-resolution Orbitrap mass spectrometry (MS). A significant fraction (36% based on dissolved organic carbon) of SRFA passed through the dialysis membrane. The fraction of SRFA in the dialysate had a different UV-visible absorption spectrum and was enriched in low molecular weight molecules with a more aliphatic composition relative to the initial SRFA solution. Comparison of the SRFA spectra collected by Orbitrap MS and Fourier transform ion cyclotron resonance MS (FT-ICR MS) demonstrated that the mass accuracy of the Orbitrap MS is sufficient for determination of unique molecular formulas of compounds with masses masses detected by Orbitrap MS were found in the 100-200 Da mass range. Many of these low molecular masses corresponded to molecular formulas of previously identified compounds in organic matter, lignin, and plants, and the use of the standard addition method provided an upper concentration estimate of selected target compounds in SRFA. Collectively, these results provide evidence that SRFA contains low molecular weight components that are present individually or in loosely bound assemblies.

The study of development of welded compact plate heat exchanger for high temperature and pressure

International Nuclear Information System (INIS)

Park, Jae Hong; Lim, Hyug; Kim, Jung Kyu; Cho, Sung Youl; Kwon, Oh Boong

2009-01-01

In view of space saving, the design of more compact heat exchangers is relatively important. Also, to meet the demand for saving energy and resources today, manufacturers are trying to enhance efficiency and reduce the size and weight of heat exchangers. Over the past decade, there has been tremendous advancement in the manufacturing technology of high efficiency heat exchangers. This has allowed the use of smaller and high performance heat exchangers. Consequently, the use of smaller and high performance heat exchanger becomes popular in the design of heat exchangers. Welded compact plate heat exchanger is used in high temperature and pressure. In the design of heat exchanger, it is necessary to understand the heat transfer characteristics, so performance data are provided to help design of this type heat exchanger.

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

International Nuclear Information System (INIS)

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

1982-01-01

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

Isolation and Molecular Characterization of High Molecular Weight Glutenin Subunit Genes 1Bx13 and 1By16 from Hexaploid Wheat

Institute of Scientific and Technical Information of China (English)

Bin-Shuang Pang; Xue-Yong Zhang

2008-01-01

The high molecular weight glutenin subunit (HMW-GS) pair 1Bx13+1Byt6 are recognized to positively correlate with bread-making quality; however, their molecular data remain unknown. In order to reveal the mechanism by which 1By16 and 1Bx13 creates high quality, their open reading frames (ORFs) were amplified from common wheat Atlas66 and Jimai 20 using primers that were designed based on published sequences of HMW glutenin genes. The ORF of 1By16 was 2220bp, deduced into 738 amino acid residues with seven cysteines including 59 hexapeptides and 22 nanopeptides motifs. The ORF of 1Bx13 was 2385bp, deduced into 795 amino acid residues with four cysteines including 68 hexapeptides, 25 nanopeptides and six tripeptides motifs. We found that 1By16 was the largest y-type HMW glutenin gene described to date in common wheat. The 1By16 had 36 amino acid residues inserted in the central repetitive domain compared with 1By15. Expression in bacteria and western-blot tests confirmed that the sequence cloned was the ORF of HMW-GS 1By16, and that 1Bx13 was one of the largest 1Bx genes that have been described so far in common wheat, exhibiting a hexapeptide (PGQGQQ) insertion in the end of central repetitive domain compared with 1Bx7. A phylogenetic tree based on the deduced full-length amino acid sequence alignment of the published HMW-GS genes showed that the 1By16 was clustered with Glu-IB-2, and that the 1Bx13 was clustered with Glu-1B-1 alleles.

Enhanced hyluronic acid production in Streptococcus zooepidemicus by over expressing HasA and molecular weight control with Niscin and glucose

Directory of Open Access Journals (Sweden)

Alireza Zakeri

2017-12-01

Full Text Available Hyaluronic acid (HA is a high molecular weight linear polysaccharide, endowed with unique physiological and biological properties. Given its unique properties, HA have unprecedented applications in the fields of medicine and cosmetics. The ever growing demand for HA production is the driving force behind the need for finding and developing novel and amenable sources of the HA producers. Microbial fermentation of Streptococcus zooepidemicus deemed as one the most expeditious and pervasive methods of HA production. Herein, a wild type Streptococcus zooepidemicus, intrinsically expressing high levels of HA, was selected and optimized for HA production. HasA gene was amplified and introduced into the wild type Streptococcus zooepidemicus, under the control of Nisin promoter. The HasA over-expression increased the HA production, while the molecular weight was decreased. In order to compensate for molecular weight loss, the glucose concentration was increased to an optimum amount of 90 g/L. It is hypostatizes that excess glucose would rectify the distribution of the monomers and each HasA molecule would be provided with sufficient amount of substrates to lengthen the HA molecules. Arriving at an improved strain and optimized cultivating condition would pave the way for industrial grade HA production with high quality and quantity. Keywords: Streptococcus zooepidemicus, Hyaluronic acid, HasA, Glucose, Molecular weight

Molecular dynamics study on heat transport from single-walled carbon nanotubes to Si substrate

Energy Technology Data Exchange (ETDEWEB)

Feng, Ya; Zhu, Jie, E-mail: zhujie@iet.cn; Tang, Da-Wei

2015-02-06

In this paper, non-equilibrium molecular dynamics simulations were performed to investigate the heat transport between a vertically aligned single-walled carbon nanotube (SWNT) and Si substrate, to find out the influence of temperature and system sizes, including diameter and length of SWNT and measurements of substrate. Results revealed that high temperature hindered heat transport in SWNT itself but was a beneficial stimulus for heat transport at interface of SWNT and Si. Furthermore, the system sizes strongly affected the peaks in vibrational density of states of Si, which led to interfacial thermal conductance dependent on system sizes. - Highlights: • NEMD is performed to simulate the heat transport from SWNT to Si substrate. • We analyze both interfacial thermal conductance and thermal conductivity of SWNT. • High temperature is a beneficial stimulus for heat transport at the interface. • Interfacial thermal conductance strongly depends on the sizes of SWNT and substrate. • We calculate VDOS of C and Si atoms to analyze phonon couplings between them.

Characterization of labile organic carbon in coastal wetland soils of the Mississippi River deltaic plain: Relationships to carbon functionalities

Energy Technology Data Exchange (ETDEWEB)

Dodla, Syam K. [School of Plant, Environmental and Soil Sciences, Louisiana State Univ. Agricultural Center, Baton Rouge, LA 70803 (United States); Wang, Jim J., E-mail: jjwang@agcenter.lsu.edu [School of Plant, Environmental and Soil Sciences, Louisiana State Univ. Agricultural Center, Baton Rouge, LA 70803 (United States); DeLaune, Ronald D. [Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, Baton Rouge, LA 70803 (United States)

2012-10-01

Adequate characterization of labile organic carbon (LOC) is essential to the understanding of C cycling in soil. There has been very little evaluation about the nature of LOC characterizations in coastal wetlands, where soils are constantly influenced by different redox fluctuations and salt water intrusions. In this study, we characterized and compared LOC fractions in coastal wetland soils of the Mississippi River deltaic plain using four different methods including 1) aerobically mineralizable C (AMC), 2) cold water extractable C (CWEC), 3) hot water extractable C (HWEC), and 4) salt extractable C (SEC), as well as acid hydrolysable C (AHC) which includes both labile and slowly degradable organic C. Molecular organic C functional groups of these wetland soils were characterized by {sup 13}C solid-state nuclear magnetic resonance (NMR). The LOC and AHC increased with soil organic C (SOC) regardless of wetland soil type. The LOC estimates by four different methods were positively and significantly linearly related to each other (R{sup 2} = 0.62-0.84) and with AHC (R{sup 2} = 0.47-0.71). The various LOC fractions accounted for {<=} 4.3% of SOC whereas AHC fraction represented 16-49% of SOC. AMC was influenced positively by O/N-alkyl and carboxyl C but negatively by alkyl C, whereas CWEC and SEC fractions were influenced only positively by carboxyl C but negatively by alkyl C in SOC. On the other hand, HWEC fraction was found to be only influenced positively by carbonyl C, and AHC positively by O/N-alkyl and alkyl C but negatively by aromatic C groups in SOC. Overall these relations suggested different contributions of various molecular organic C moieties to LOC in these wetlands from those often found for upland soils. The presence of more than 50% non-acid hydrolysable C suggested the dominance of relatively stable SOC pool that would be sequestered in these Mississippi River deltaic plain coastal wetland soils. The results have important implications to the

Excavation of attractor modules for nasopharyngeal carcinoma via integrating systemic module inference with attract method.

Science.gov (United States)

Jiang, T; Jiang, C-Y; Shu, J-H; Xu, Y-J

2017-07-10

The molecular mechanism of nasopharyngeal carcinoma (NPC) is poorly understood and effective therapeutic approaches are needed. This research aimed to excavate the attractor modules involved in the progression of NPC and provide further understanding of the underlying mechanism of NPC. Based on the gene expression data of NPC, two specific protein-protein interaction networks for NPC and control conditions were re-weighted using Pearson correlation coefficient. Then, a systematic tracking of candidate modules was conducted on the re-weighted networks via cliques algorithm, and a total of 19 and 38 modules were separately identified from NPC and control networks, respectively. Among them, 8 pairs of modules with similar gene composition were selected, and 2 attractor modules were identified via the attract method. Functional analysis indicated that these two attractor modules participate in one common bioprocess of cell division. Based on the strategy of integrating systemic module inference with the attract method, we successfully identified 2 attractor modules. These attractor modules might play important roles in the molecular pathogenesis of NPC via affecting the bioprocess of cell division in a conjunct way. Further research is needed to explore the correlations between cell division and NPC.

Purification and characterization of factors produced by Aspergillus fumigatus which affect human ciliated respiratory epithelium.

Science.gov (United States)

Amitani, R; Taylor, G; Elezis, E N; Llewellyn-Jones, C; Mitchell, J; Kuze, F; Cole, P J; Wilson, R

1995-09-01

The mechanisms by which Aspergillus fumigatus colonizes the respiratory mucosa are unknown. Culture filtrates of eight of nine clinical isolates of A. fumigatus slowed ciliary beat frequency and damaged human respiratory epithelium in vitro. These changes appeared to occur concurrently. Culture filtrates of two clinical isolates of Candida albicans had no effect on ciliated epithelium. We have purified and characterized cilioinhibitory factors of a clinical isolate of A. fumigatus. The cilioinhibitory activity was heat labile, reduced by dialysis, and partially extractable into chloroform. The activity was associated with both high- and low-molecular-weight factors, as determined by gel filtration on Sephadex G-50. A low-molecular-weight cilioinhibitory factor was further purified by reverse-phase high-performance liquid chromatography and shown by mass spectrometry to be gliotoxin, a known metabolite of A. fumigatus. Gliotoxin significantly slowed ciliary beat frequency in association with epithelial damage at concentrations above 0.2 microgram/ml; other Aspergillus toxins, i.e., fumagillin and helvolic acid, were also cilioinhibitory but at much higher concentrations. High-molecular-weight (> or = 35,000 and 25,000) cilioinhibitory materials had neither elastolytic nor proteolytic activity and remain to be identified. Thus, A. fumigatus produces a number of biologically active substances which slow ciliary beating and damage epithelium and which may influence colonization of the airways.

Evaluating self and partner physical attractiveness.

Science.gov (United States)

Swami, Viren; Furnham, Adrian; Georgiades, Chrissa; Pang, Lily

2007-03-01

This study used a novel questionnaire to examine ratings of self and partner physical attractiveness. Seventy-two men and 83 women estimated their own and their opposite-sex partner's overall physical attractiveness and the attractiveness of various body parts and measures. They also answered six simple questions concerning physical attractiveness. Results showed significant gender differences in self-estimates of overall facial attractiveness and upper body features. In general, and regardless of gender, participants rated their opposite-sex partners as being significantly more attractive than themselves. In addition, the results showed that body weight and facial attractiveness were the best predictors of overall physical attractiveness. Implications of these results in terms of social biases are considered.

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

International Nuclear Information System (INIS)

Miller, H.C.

1999-01-01

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

Achieving Cultural Congruency in Weight Loss Interventions: Can a Spirituality-Based Program Attract and Retain an Inner-City Community Sample?

Science.gov (United States)

Davis, Chad; Dutton, William Blake; Durant, Taryn; Annunziato, Rachel A.; Marcotte, David

2014-01-01

Ethnic minorities continue to be disproportionately affected by obesity and are less likely to access healthcare than Caucasians. It is therefore imperative that researchers develop novel methods that will attract these difficult-to-reach groups. The purpose of the present study is to describe characteristics of an urban community sample attracted to a spiritually based, weight loss intervention. Methods. Thirteen participants enrolled in a pilot version of Spiritual Self-Schema Therapy (3S) applied to disordered eating behavior and obesity. Treatment consisted of 12 one-hour sessions in a group therapy format. At baseline, participants were measured for height and weight and completed a battery of self-report measures. Results. The sample was predominantly African-American and Hispanic and a large percentage of the sample was male. Mean baseline scores of the EDE-Q, YFAS, and the CES-D revealed clinically meaningful levels of eating disordered pathology and depression, respectively. The overall attrition rate was quite low for interventions targeting obesity. Discussion. This application of a spiritually centered intervention seemed to attract and retain a predominantly African-American and Hispanic sample. By incorporating a culturally congruent focus, this approach may have been acceptable to individuals who are traditionally more difficult to reach. PMID:24804086

Achieving Cultural Congruency in Weight Loss Interventions: Can a Spirituality-Based Program Attract and Retain an Inner-City Community Sample?

Directory of Open Access Journals (Sweden)

Chad Davis

2014-01-01

Full Text Available Ethnic minorities continue to be disproportionately affected by obesity and are less likely to access healthcare than Caucasians. It is therefore imperative that researchers develop novel methods that will attract these difficult-to-reach groups. The purpose of the present study is to describe characteristics of an urban community sample attracted to a spiritually based, weight loss intervention. Methods. Thirteen participants enrolled in a pilot version of Spiritual Self-Schema Therapy (3S applied to disordered eating behavior and obesity. Treatment consisted of 12 one-hour sessions in a group therapy format. At baseline, participants were measured for height and weight and completed a battery of self-report measures. Results. The sample was predominantly African-American and Hispanic and a large percentage of the sample was male. Mean baseline scores of the EDE-Q, YFAS, and the CES-D revealed clinically meaningful levels of eating disordered pathology and depression, respectively. The overall attrition rate was quite low for interventions targeting obesity. Discussion. This application of a spiritually centered intervention seemed to attract and retain a predominantly African-American and Hispanic sample. By incorporating a culturally congruent focus, this approach may have been acceptable to individuals who are traditionally more difficult to reach.

Achieving cultural congruency in weight loss interventions: can a spirituality-based program attract and retain an inner-city community sample?

Science.gov (United States)

Davis, Chad; Dutton, William Blake; Durant, Taryn; Annunziato, Rachel A; Marcotte, David

2014-01-01

Ethnic minorities continue to be disproportionately affected by obesity and are less likely to access healthcare than Caucasians. It is therefore imperative that researchers develop novel methods that will attract these difficult-to-reach groups. The purpose of the present study is to describe characteristics of an urban community sample attracted to a spiritually based, weight loss intervention. METHODS. Thirteen participants enrolled in a pilot version of Spiritual Self-Schema Therapy (3S) applied to disordered eating behavior and obesity. Treatment consisted of 12 one-hour sessions in a group therapy format. At baseline, participants were measured for height and weight and completed a battery of self-report measures. The sample was predominantly African-American and Hispanic and a large percentage of the sample was male. Mean baseline scores of the EDE-Q, YFAS, and the CES-D revealed clinically meaningful levels of eating disordered pathology and depression, respectively. The overall attrition rate was quite low for interventions targeting obesity. This application of a spiritually centered intervention seemed to attract and retain a predominantly African-American and Hispanic sample. By incorporating a culturally congruent focus, this approach may have been acceptable to individuals who are traditionally more difficult to reach.

Collapse and coexistence for a molecular braid with an attractive interaction component subject to mechanical forces.

Science.gov (United States)

Lee, Dominic J O'

2015-04-15

Dual mechanical braiding experiments provide a useful tool with which to investigate the nature of interactions between rod-like molecules, for instance actin and DNA. In conditions close to molecular condensation, one would expect an appearance of a local minimum in the interaction potential between the two molecules. We investigate this situation, introducing an attractive component into the interaction potential, using a model developed for describing such experiments. We consider both attractive interactions that do not depend on molecular structure and those which depend on a DNA-like helix structure. In braiding experiments, an attractive term may lead to certain effects. A local minimum may cause molecules to collapse from a loosely braided configuration into a tight one, occurring at a critical value of the moment applied about the axis of the braid. For a fixed number of braid pitches, this may lead to coexistence between the two braiding states, tight and loose. Coexistence implies certain proportions of the braid are in each state, their relative size depending on the number of braid pitches. This manifests itself as a linear dependence in numerically calculated quantities as functions of the number of braid pitches. Also, in the collapsed state, the braid radius stays roughly constant. Furthermore, if the attractive interaction is helix dependent, the left-right handed braid symmetry is broken. For a DNA like charge distribution, using the Kornyshev-Leikin interaction model, our results suggest that significant braid collapse and coexistence only occurs for left handed braids. Regardless of the interaction model, the study highlights the possible qualitative physics of braid collapse and coexistence; and the role helix specific forces might play, if important. The model could be used to connect other microscopic theories of interaction with braiding experiments.

Collapse and coexistence for a molecular braid with an attractive interaction component subject to mechanical forces

International Nuclear Information System (INIS)

Lee, Dominic J

2015-01-01

Dual mechanical braiding experiments provide a useful tool with which to investigate the nature of interactions between rod-like molecules, for instance actin and DNA. In conditions close to molecular condensation, one would expect an appearance of a local minimum in the interaction potential between the two molecules. We investigate this situation, introducing an attractive component into the interaction potential, using a model developed for describing such experiments. We consider both attractive interactions that do not depend on molecular structure and those which depend on a DNA-like helix structure. In braiding experiments, an attractive term may lead to certain effects. A local minimum may cause molecules to collapse from a loosely braided configuration into a tight one, occurring at a critical value of the moment applied about the axis of the braid. For a fixed number of braid pitches, this may lead to coexistence between the two braiding states, tight and loose. Coexistence implies certain proportions of the braid are in each state, their relative size depending on the number of braid pitches. This manifests itself as a linear dependence in numerically calculated quantities as functions of the number of braid pitches. Also, in the collapsed state, the braid radius stays roughly constant. Furthermore, if the attractive interaction is helix dependent, the left-right handed braid symmetry is broken. For a DNA like charge distribution, using the Kornyshev–Leikin interaction model, our results suggest that significant braid collapse and coexistence only occurs for left handed braids. Regardless of the interaction model, the study highlights the possible qualitative physics of braid collapse and coexistence; and the role helix specific forces might play, if important. The model could be used to connect other microscopic theories of interaction with braiding experiments. (paper)

Anisotropic frictional heating and defect generation in cyclotrimethylene-trinitramine molecular crystals

Science.gov (United States)

Rajak, Pankaj; Mishra, Ankit; Sheng, Chunyang; Tiwari, Subodh; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya

2018-05-01

Anisotropic frictional response and corresponding heating in cyclotrimethylene-trinitramine molecular crystals are studied using molecular dynamics simulations. The nature of damage and temperature rise due to frictional forces is monitored along different sliding directions on the primary slip plane, (010), and on non-slip planes, (100) and (001). Correlations between the friction coefficient, deformation, and frictional heating are established. We find that the friction coefficients on slip planes are smaller than those on non-slip planes. In response to sliding on a slip plane, the crystal deforms easily via dislocation generation and shows less heating. On non-slip planes, due to the inability of the crystal to deform via dislocation generation, a large damage zone is formed just below the contact area, accompanied by the change in the molecular ring conformation from chair to boat/half-boat. This in turn leads to a large temperature rise below the contact area.

High-Performance n-Channel Organic Transistors Using High-Molecular-Weight Electron-Deficient Copolymers and Amine-Tailed Self-Assembled Monolayers.

Science.gov (United States)

Wang, Yang; Hasegawa, Tsukasa; Matsumoto, Hidetoshi; Mori, Takehiko; Michinobu, Tsuyoshi

2018-03-01

While high-performance p-type semiconducting polymers are widely reported, their n-type counterparts are still rare in terms of quantity and quality. Here, an improved Stille polymerization protocol using chlorobenzene as the solvent and palladium(0)/copper(I) as the catalyst is developed to synthesize high-quality n-type polymers with number-average molecular weight up to 10 5 g mol -1 . Furthermore, by sp 2 -nitrogen atoms (sp 2 -N) substitution, three new n-type polymers, namely, pBTTz, pPPT, and pSNT, are synthesized, and the effect of different sp 2 -N substitution positions on the device performances is studied for the first time. It is found that the incorporation of sp 2 -N into the acceptor units rather than the donor units results in superior crystalline microstructures and higher electron mobilities. Furthermore, an amine-tailed self-assembled monolayer (SAM) is smoothly formed on a Si/SiO 2 substrate by a simple spin-coating technique, which can facilitate the accumulation of electrons and lead to more perfect unipolar n-type transistor performances. Therefore, a remarkably high unipolar electron mobility up to 5.35 cm 2 V -1 s -1 with a low threshold voltage (≈1 V) and high on/off current ratio of ≈10 7 is demonstrated for the pSNT-based devices, which are among the highest values for unipolar n-type semiconducting polymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Effect of Polymer Molecular Weight on Citrate Crosslinked ...

African Journals Online (AJOL)

Erah

Purpose: To develop citrate crosslinked chitosan films using chitosan of different molecular weights. (MW) in .... left to stand until trapped air bubbles ... blotted out carefully with filter paper from the .... potential as biodegradable stent coatings. J.

Black Tea High-Molecular-Weight Polyphenol-Rich Fraction Promotes Hypertrophy during Functional Overload in Mice

Directory of Open Access Journals (Sweden)

Yuki Aoki

2017-03-01

Full Text Available Mitochondria activation factor (MAF is a high-molecular-weight polyphenol extracted from black tea that stimulates training-induced 5′ adenosine monophosphate-activated protein kinase (AMPK activation and improves endurance capacity. Originally, MAF was purified from black tea using butanol and acetone, making it unsuitable for food preparation. Hence, we extracted a MAF-rich sample “E80” from black tea, using ethanol and water only. Here, we examined the effects of E80 on resistance training. Eight-week old C57BL/6 mice were fed with a normal diet or a diet containing 0.5% E80 for 4, 7 and 14 days under conditions of functional overload. It was found that E80 administration promoted overload-induced hypertrophy and induced phosphorylation of the Akt/mammalian target of rapamycin (mTOR pathway proteins, such as Akt, P70 ribosomal protein S6 kinase (p70S6K, and S6 in the plantaris muscle. Therefore, functional overload and E80 administration accelerated mTOR signaling and increased protein synthesis in the muscle, thereby inducing hypertrophy.

Non-labile Soil Nitrogen Retention beneath Three Tree Species in a Tropical Plantation

Science.gov (United States)

Jason P. Kaye; Dan Binkley; Xiaoming Zou

2002-01-01

Soil organic matter is the largest sink for N additions to forests. Species composition may affect soilNretention by altering the amount or proportion of added N stored in non-labile organic pools. We measured 15N tracer retention in labile and non-labile pools of surface (0–20 cm) mineral soils, 7 yr after the tracer was applied to a 9 yr-old Puerto Rican tree...

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

International Nuclear Information System (INIS)

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

2010-01-01

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

Molecular programs induced by heat acclimation confer neuroprotection against TBI and hypoxic insults via cross-tolerance mechanisms

Directory of Open Access Journals (Sweden)

Michal eHorowitz

2015-07-01

Full Text Available Neuroprotection following prolonged exposure to high ambient temperatures (heat acclimation HA develops via altered molecular programs such as cross-tolerance (Heat Acclimation -Neuroprotection Cross-Tolerance -HANCT. The mechanisms underlying cross-tolerance depend on enhanced on-demand protective pathways evolving during acclimation. The protection achieved is long lasting and limits the need for de novo recruitment of cytoprotective pathways upon exposure to novel stressors. Using mouse and rat acclimated phenotypes, we will focus on the impact of heat acclimation on Angiotensin II-AT2 receptors in neurogenesis and on HIF-1 as key mediators in spontaneous recovery and HANCT after traumatic brain injury (TBI. The neuroprotective consequences of heat acclimation on NMDA and AMPA receptors will be discussed using the global hypoxia model. A behavioral-molecular link will be crystallized. The differences between HANCT and consensus preconditioning will be reviewed.

Heat Exchangers for Utilization of the Heat of High-Temperature Geothermal Brines

Science.gov (United States)

Alkhasov, A. B.; Alkhasova, D. A.

2018-03-01

The basic component of two-circuit geothermal systems is the heat exchanger. When used in geothermal power systems, conventional shell-and-tube and plate heat exchangers cause problems related to the cleaning of the latter from salt-deposition and corrosion products. Their lifetime does not exceed, as a rule, 1 year. To utilize the heat of high-temperature geothermal brines, a heat exchanger of the "tube-in-tube" type is proposed. A heat exchanger of this design has been operated for several years in Ternair geothermal steam field; in this heat exchanger, the thermal potential of the saline thermal water is transferred to the fresh water of the secondary circuit of the heating system for apartment houses. The reduction in the weight and size characteristics of the heat exchangers is a topical problem that can be solved with the help of heat transfer enhancers. To enhance the heat transfer process in the heat exchanger, longitudinal ribbing of the heat exchange surface is proposed. The increase in the heat exchange surface from the heat carrier side by ribbing results in an increase in the amount of the heat transferred from the heating agent. The heat exchanger is easy to manufacture and is assembled out of components comprised of two concentrically positioned tubes of a definite length, 3-6 m, serially connected with each other. The method for calculation of the impact of the number and the size of the longitudinal ribs on the heat transfer in the well heat exchanger is presented and a criterion for the selection of the optimal number and design parameters of the ribs is formulated. To prevent the corrosion and salt deposition in the heat exchanger, the use of an effective OEDFK (oxyethylidenediphosphonic acid) agent is proposed. This agent has a long-lasting corrosion-inhibiting and antiscaling effect, which is explained by the formation of a strongly adhesive chelate layer difficult to wash off the surface. The passivating OEDFK layer is restored by periodical

Maternal emotion socialization differentially predicts third-grade children's emotion regulation and lability.

Science.gov (United States)

Rogers, Megan L; Halberstadt, Amy G; Castro, Vanessa L; MacCormack, Jennifer K; Garrett-Peters, Patricia

2016-03-01

Numerous parental emotion socialization factors have been implicated as direct and indirect contributors to the development of children's emotional competence. To date, however, no study has combined parents' emotion-related beliefs, behaviors, and regulation strategies in one model to assess their cumulative-as well as unique-contributions to children's emotion regulation. We considered the 2 components that have recently been distinguished: emotion regulation and emotional lability. We predicted that mothers' beliefs about the value of and contempt for children's emotions, mothers' supportive and nonsupportive reactions to their children's emotions, as well as mothers' use of cognitive reappraisal and suppression of their own emotions would each contribute unique variance to their children's emotion regulation and lability, as assessed by children's teachers. The study sample consisted of an ethnically and socioeconomically diverse group of 165 mothers and their third-grade children. Different patterns emerged for regulation and lability: Controlling for family income, child gender, and ethnicity, only mothers' lack of suppression as a regulatory strategy predicted greater emotion regulation in children, whereas mothers' valuing of children's emotions, mothers' lack of contempt for children's emotions, mothers' use of cognitive reappraisal to reinterpret events, and mothers' lack of emotional suppression predicted less lability in children. These findings support the divergence of emotion regulation and lability as constructs and indicate that, during middle childhood, children's lability may be substantially and uniquely affected by multiple forms of parental socialization. (c) 2016 APA, all rights reserved).

Semiquantum molecular dynamics simulation of thermal properties and heat transport in low-dimensional nanostructures

Science.gov (United States)

Savin, Alexander V.; Kosevich, Yuriy A.; Cantarero, Andres

2012-08-01

We present a detailed description of semiquantum molecular dynamics simulation of stochastic dynamics of a system of interacting particles. Within this approach, the dynamics of the system is described with the use of classical Newtonian equations of motion in which the effects of phonon quantum statistics are introduced through random Langevin-like forces with a specific power spectral density (the color noise). The color noise describes the interaction of the molecular system with the thermostat. We apply this technique to the simulation of thermal properties and heat transport in different low-dimensional nanostructures. We describe the determination of temperature in quantum lattice systems, to which the equipartition limit is not applied. We show that one can determine the temperature of such a system from the measured power spectrum and temperature- and relaxation-rate-independent density of vibrational (phonon) states. We simulate the specific heat and heat transport in carbon nanotubes, as well as the heat transport in molecular nanoribbons with perfect (atomically smooth) and rough (porous) edges, and in nanoribbons with strongly anharmonic periodic interatomic potentials. We show that the effects of quantum statistics of phonons are essential for the carbon nanotube in the whole temperature range T<500K, in which the values of the specific heat and thermal conductivity of the nanotube are considerably less than that obtained within the description based on classical statistics of phonons. This conclusion is also applicable to other carbon-based materials and systems with high Debye temperature like graphene, graphene nanoribbons, fullerene, diamond, diamond nanowires, etc. We show that the existence of rough edges and quantum statistics of phonons change drastically the low-temperature thermal conductivity of the nanoribbon in comparison with that of the nanoribbon with perfect edges and classical phonon dynamics and statistics. The semiquantum molecular

Size and shape of soil humic acids estimated by viscosity and molecular weight.

Science.gov (United States)

Kawahigashi, Masayuki; Sumida, Hiroaki; Yamamoto, Kazuhiko

2005-04-15

Ultrafiltration fractions of three soil humic acids were characterized by viscometry and high performance size-exclusion chromatography (HPSEC) in order to estimate shapes and hydrodynamic sizes. Intrinsic viscosities under given solute/solvent/temperature conditions were obtained by extrapolating the concentration dependence of reduced viscosities to zero concentration. Molecular mass (weight average molecular weight (M (w)) and number average molecular weight (M (n))) and hydrodynamic radius (R(H)) were determined by HPSEC using pullulan as calibrant. Values of M (w) and M (n) ranged from 15 to 118 x 10(3) and from 9 to 50 x 10(3) (g mol(-1)), respectively. Polydispersity, as indicated by M (w)/M (n), increased with increasing filter size from 1.5 to 2.4. The hydrodynamic radii (R(H)) ranged between 2.2 and 6.4 nm. For each humic acid, M (w) and [eta] were related. Mark-Houwink coefficients calculated on the basis of the M (w)-[eta] relationships suggested restricted flexible chains for two of the humic acids and a branched structure for the third humic acid. Those structures probably behave as hydrated sphere colloids in a good solvent. Hydrodynamic radii of fractions calculated from [eta] using Einstein's equation, which is applicable to hydrated sphere colloids, ranged from 2.2 to 7.1 nm. These dimensions are fit to the size of nanospaces on and between clay minerals and micropores in soil particle aggregates. On the other hand, the good agreement of R(H) values obtained by applying Einstein's equation with those directly determined by HPSEC suggests that pullulan is a suitable calibrant for estimation of molecular mass and size of humic acids by HPSEC.

Shock compression and flash-heating of molecular adsorbates on the picosecond time scale

Science.gov (United States)

Berg, Christopher Michael

An ultrafast nonlinear coherent laser spectroscopy termed broadband multiplex vibrational sum-frequency generation (SFG) with nonresonant suppression was employed to monitor vibrational transitions of molecular adsorbates on metallic substrates during laser-driven shock compression and flash-heating. Adsorbates were in the form of well-ordered self-assembled monolayers (SAMs) and included molecular explosive simulants, such as nitroaromatics, and long chain-length alkanethiols. Based on reflectance measurements of the metallic substrates, femtosecond flash-heating pulses were capable of producing large-amplitude temperature jumps with DeltaT = 500 K. Laser-driven shock compression of SAMs produced pressures up to 2 GPa, where 1 GPa ≈ 1 x 104 atm. Shock pressures were estimated via comparison with frequency shifts observed in the monolayer vibrational transitions during hydrostatic pressure measurements in a SiC anvil cell. Molecular dynamics during flash-heating and shock loading were probed with vibrational SFG spectroscopy with picosecond temporal resolution and sub-nanometer spatial resolution. Flash-heating studies of 4-nitrobenzenethiolate (NBT) on Au provided insight into effects from hot-electron excitation of the molecular adsorbates at early pump-probe delay times. At longer delay times, effects from the excitation of SAM lattice modes and lower-energy NBT vibrations were shown. In addition, flash-heating studies of alkanethiolates demonstrated chain disordering behaviors as well as interface thermal conductances across the Au-SAM junction, which was of specific interest within the context of molecular electronics. Shock compression studies of molecular explosive simulants, such as 4-nitrobenzoate (NBA), demonstrated the proficiency of this technique to observe shock-induced molecular dynamics, in this case orientational dynamics, on the picosecond time scale. Results validated the utilization of these refined shock loading techniques to probe the shock

Influence of Host Interleukin-10 Polymorphisms on Development of Traveler's Diarrhea Due to Heat-Labile Enterotoxin-Producing Escherichia coli in Travelers from the United States Who Are Visiting Mexico▿

Science.gov (United States)

Flores, Jose; DuPont, Herbert L.; Lee, Stephanie A.; Belkind-Gerson, Jaime; Paredes, Mercedes; Mohamed, Jamal A.; Armitige, Lisa Y.; Guo, Dong-Chuan; Okhuysen, Pablo C.

2008-01-01

Up to 60% of U.S. visitors to Mexico develop traveler's diarrhea (TD), mostly due to enterotoxigenic Escherichia coli (ETEC) strains that produce heat-labile (LT) and/or heat-stable (ST) enterotoxins. Distinct single-nucleotide polymorphisms (SNPs) within the interleukin-10 (IL-10) promoter have been associated with high, intermediate, or low production of IL-10. We conducted a prospective study to investigate the association of SNPs in the IL-10 promoter and the occurrence of TD in ETEC LT-exposed travelers. Sera from U.S. travelers to Mexico collected on arrival and departure were studied for ETEC LT seroconversion by using cholera toxin as the antigen. Pyrosequencing was performed to genotype IL-10 SNPs. Stools from subjects who developed diarrhea were also studied for other enteropathogens. One hundred twenty-one of 569 (21.3%) travelers seroconverted to ETEC LT, and among them 75 (62%) developed diarrhea. Symptomatic seroconversion was more commonly seen in subjects who carried a genotype producing high levels of IL-10; it was seen in 83% of subjects with the GG genotype versus 54% of subjects with the AA genotype at IL-10 gene position −1082 (P, 0.02), in 71% of those with the CC genotype versus 33% of those with the TT genotype at position −819 (P, 0.005), and in 71% of those with the CC genotype versus 38% of those with the AA genotype at position −592 (P, 0.02). Travelers with the GCC haplotype were more likely to have symptomatic seroconversion than those with the ATA haplotype (71% versus 38%; P, 0.002). Travelers genetically predisposed to produce high levels of IL-10 were more likely to experience symptomatic ETEC TD. PMID:18579697

Influence of host interleukin-10 polymorphisms on development of traveler's diarrhea due to heat-labile enterotoxin-producing Escherichia coli in travelers from the United States who are visiting Mexico.

Science.gov (United States)

Flores, Jose; DuPont, Herbert L; Lee, Stephanie A; Belkind-Gerson, Jaime; Paredes, Mercedes; Mohamed, Jamal A; Armitige, Lisa Y; Guo, Dong-Chuan; Okhuysen, Pablo C

2008-08-01

Up to 60% of U.S. visitors to Mexico develop traveler's diarrhea (TD), mostly due to enterotoxigenic Escherichia coli (ETEC) strains that produce heat-labile (LT) and/or heat-stable (ST) enterotoxins. Distinct single-nucleotide polymorphisms (SNPs) within the interleukin-10 (IL-10) promoter have been associated with high, intermediate, or low production of IL-10. We conducted a prospective study to investigate the association of SNPs in the IL-10 promoter and the occurrence of TD in ETEC LT-exposed travelers. Sera from U.S. travelers to Mexico collected on arrival and departure were studied for ETEC LT seroconversion by using cholera toxin as the antigen. Pyrosequencing was performed to genotype IL-10 SNPs. Stools from subjects who developed diarrhea were also studied for other enteropathogens. One hundred twenty-one of 569 (21.3%) travelers seroconverted to ETEC LT, and among them 75 (62%) developed diarrhea. Symptomatic seroconversion was more commonly seen in subjects who carried a genotype producing high levels of IL-10; it was seen in 83% of subjects with the GG genotype versus 54% of subjects with the AA genotype at IL-10 gene position -1082 (P, 0.02), in 71% of those with the CC genotype versus 33% of those with the TT genotype at position -819 (P, 0.005), and in 71% of those with the CC genotype versus 38% of those with the AA genotype at position -592 (P, 0.02). Travelers with the GCC haplotype were more likely to have symptomatic seroconversion than those with the ATA haplotype (71% versus 38%; P, 0.002). Travelers genetically predisposed to produce high levels of IL-10 were more likely to experience symptomatic ETEC TD.

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

NARCIS (Netherlands)

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

1998-01-01

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

The use of microwave tissue fixation to demonstrate the in vivo phosphorylation of an acidic 80,000 molecular weight protein in the rat neocortex following treatment with soman

International Nuclear Information System (INIS)

Mobley, P.L.; Gonzalez, N.E.

1991-01-01

Studies were conducted to determine if soman, a cholinesterase inhibitor, could activate the protein kinase C system in the rat neocortex. Using microwave radiation for rapid tissue fixation, it was demonstrated that treatment with soman increased 32 P incorporation into an acidic 80,000 molecular weight, heat-stable protein in vivo. Based on relative molecular weight and isoelectric point this protein appears to be identical to a protein identified as a substrate for protein kinase C. Additionally, a protein of the same molecular weight and isoelectric point could be phosphorylated in tissue slices prepared from the neocortex by cholinergic dependent mechanisms. Also, treatment with soman decreased protein kinase C in the soluble fraction of this brain region; however, no corresponding increase was observed in the particulate fraction. These results suggest that soman can activate protein kinase C in vivo, and demonstrate the utility of using microwave tissue fixation to study protein phosphorylation events in vivo

The use of microwave tissue fixation to demonstrate the in vivo phosphorylation of an acidic 80,000 molecular weight protein in the rat neocortex following treatment with soman

Energy Technology Data Exchange (ETDEWEB)

Mobley, P.L.; Gonzalez, N.E. (Univ. of Texas Health Science Center, San Antonio (United States))

1991-01-01

Studies were conducted to determine if soman, a cholinesterase inhibitor, could activate the protein kinase C system in the rat neocortex. Using microwave radiation for rapid tissue fixation, it was demonstrated that treatment with soman increased {sup 32}P incorporation into an acidic 80,000 molecular weight, heat-stable protein in vivo. Based on relative molecular weight and isoelectric point this protein appears to be identical to a protein identified as a substrate for protein kinase C. Additionally, a protein of the same molecular weight and isoelectric point could be phosphorylated in tissue slices prepared from the neocortex by cholinergic dependent mechanisms. Also, treatment with soman decreased protein kinase C in the soluble fraction of this brain region; however, no corresponding increase was observed in the particulate fraction. These results suggest that soman can activate protein kinase C in vivo, and demonstrate the utility of using microwave tissue fixation to study protein phosphorylation events in vivo.

The evolution of dioecy, heterodichogamy, and labile sex expression in Acer.

Science.gov (United States)

Renner, S S; Beenken, L; Grimm, G W; Kocyan, A; Ricklefs, R E

2007-11-01

, however, a concern remains that monoecy in Acer might not always be distinguishable from labile sex expression, which needs to be addressed by long-term monitoring of monoecious trees. The 13 dioecious species occur in phylogenetically disparate clades that date back to the Late Eocene and Oligocene, judging from a fossil-calibrated relaxed molecular clock.

Phase behaviour of oat β-glucan/sodium caseinate mixtures varying in molecular weight.

Science.gov (United States)

Agbenorhevi, Jacob K; Kontogiorgos, Vassilis; Kasapis, Stefan

2013-05-01

The isothermal phase behaviour at 5 °C of mixtures of sodium caseinate and oat β-glucan isolates varying in molecular weight (MW) was investigated by means of phase diagram construction, rheometry, fluorescence microscopy and electrophoresis. Phase diagrams indicated that the compatibility of the β-glucan/sodium caseinate system increases as β-glucan MW decreases. Images of mixtures taken at various biopolymer concentrations revealed phase separated domains. Results also revealed that at the state of thermodynamic equilibrium, lower MW samples yielded considerable viscosity in the mixture. At equivalent hydrodynamic volume of β-glucan in the mixtures, samples varying in molecular weight exhibited similar flow behaviour. A deviation dependent on the protein concentration was observed for the high MW sample in the concentrated regime due to the size of β-glucan aggregates formed. Results demonstrate that by controlling the structural features of β-glucan in mixtures with sodium caseinate, informed manipulation of rheological properties in these systems can be achieved. Copyright © 2012 Elsevier Ltd. All rights reserved.

Total and high molecular weight adiponectin are elevated in patients with Laron syndrome despite marked obesity.

Science.gov (United States)

Kanety, Hannah; Hemi, Rina; Ginsberg, Shira; Pariente, Clara; Yissachar, Eleanor; Barhod, Ehud; Funahashi, Tohru; Laron, Zvi

2009-12-01

Patients with Laron syndrome (LS; primary GH insensitivity) caused by molecular defects of the GH receptor gene, are characterized by dwarfism, profound obesity, and hyperlipidemia. The aim of the current study was to evaluate adiponectin levels in LS, as obesity is known to be associated with low adiponectin. We studied nine untreated LS adult patients (5 males, 4 females) and six girls with LS receiving once-daily treatment by IGF1. Total and high molecular weight (HMW) adiponectin levels, adiponectin multimers distribution, and metabolic indices were analyzed in serum samples obtained during several years of follow-up. Adiponectin levels in the severely obese adult LS patients (percent body fat; females 61.0+/-2.5%, males 40.6+/-8.1%) were two- to three-fold higher than those reported for subjects of corresponding age, gender and degree of adiposity. Total adiponectin was significantly higher in females compared with males (21.4+/-3.5 vs 10.2+/-4.6 microg/ml, P<0.001). The elevated adiponectin in LS subjects was associated with an increased abundance of the HMW isoform, and positively correlated with body fat percentage (r=0.65, P=0.017) and leptin (r=0.65, P=0.012). There was no correlation between adiponectin levels (total and HMW) and the degree of insulin resistance in LS subjects or their blood lipids levels. Adiponectin was also high in young girls with LS (22.9+/-7.4 microg/ml) and did not change during long-term IGF1 replacement therapy. Adiponectin hypersecretion in LS, despite profound obesity, suggests that GH activity may negatively impact adiponectin secretion from adipocytes.

Relationship between the lability of sediment-bound Cd and its bioaccumulation in edible oyster.

Science.gov (United States)

Chakraborty, Parthasarathi; Ramteke, Darwin; Chakraborty, Sucharita; Chennuri, Kartheek; Bardhan, Pratirupa

2015-11-15

A linkage between Cd speciation in sediments and its bioaccumulation in edible oyster (Crassostrea sp.) from a tropical estuarine system was established. Bioaccumulation of Cd in edible oyster increased with the increasing lability and dissociation rate constants of Cd-sediment complexes in the bottom sediments. Total Cd concentration in sediment was not a good indicator of Cd-bioavailability. Increasing trace metal competition in sediments increased lability and bioavailability of Cd in the tropical estuarine sediment. Low thermodynamic stability and high bioavailability of Cd in the estuarine sediment were responsible for high bioaccumulation of Cd in edible oysters (3.2-12.2mgkg(-1)) even though the total concentration of Cd in the bottom sediment was low (0.17-0.49mgkg(-1)). Copyright © 2015 Elsevier Ltd. All rights reserved.

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

DEFF Research Database (Denmark)

Gimeno, Sofia; Forcen, Patricia; Oriol, Luis

2009-01-01

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

Knowledge Lability: Within-Person Changes in Parental Knowledge and Their Associations with Adolescent Problem Behavior.

Science.gov (United States)

Lippold, Melissa A; Fosco, Gregory M; Ram, Nilam; Feinberg, Mark E

2016-02-01

Higher levels of parental knowledge about youth activities have been associated with lower levels of youth risky behavior. Yet little is known about how parental knowledge fluctuates during early adolescence and how those fluctuations are associated with the development of problem behavior. We use the term lability to describe within-person fluctuations in knowledge over time with higher lability indicating greater fluctuations in knowledge from year-to-year. This longitudinal study of rural adolescents (N = 840) investigated if change in parental knowledge across four waves of data from grades 6 to 8 is characterized by lability, and if greater lability is associated with higher youth substance use, delinquency, and internalizing problems in grade 9. Our models indicated that only some of the variance in parental knowledge was accounted for by developmental trends. The remaining residual variance reflects within-person fluctuations around these trends, lability, and measurement and occasion-specific error. Even controlling for level and developmental trends in knowledge, higher knowledge lability (i.e., more fluctuation) was associated with increased risk for later alcohol and tobacco use, and for girls, higher delinquency and internalizing problems. Our findings suggest that lability in parental knowledge has unique implications for adolescent outcomes. The discussion focuses on mechanisms that may link knowledge lability to substance use. Interventions may be most effective if they teach parents to consistently and predictably decrease knowledge across early adolescence.

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

Science.gov (United States)

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...

Compact heat exchanger technologies for the HTRs recuperator application

International Nuclear Information System (INIS)

Thonon, B.; Breuil, E.

2001-01-01

Modern HTR nuclear power plants which are now under development (projects GT-MHR, PBMR) are based on the direct cycle concept. This concept leads to a more important efficiency compared to the steam cycle but requires the use of high performance components such as an helium/helium heat exchanger called recuperator to guarantee the cycle efficiency. Using this concept, a net plant efficiency of around 50% can be achieved in the case of an electricity generating plant. As geometric constraints are particularly important for such a gas reactor to limit the size of the primary vessels, compact heat exchangers operating at high pressure and high temperature are attractive potential solutions for the recuperator application. In this frame, Framatome and CEA have reviewed the various technologies of compact heat exchangers used in industry. The first part of the paper will give a short description of the heat exchangers technologies and their ranges of application. In a second part, a selection of potential compact heat exchangers technologies are proposed for the recuperator application. This selection will be based upon their capabilities to cope with the operating conditions parameters (pressure, temperature, flow rate) and with other parameters such as fouling, corrosion, compactness, weight, maintenance and reliability. (author)

LABILE IRON IN CELLS AND BODY FLUIDS . Physiology, Pathology and Pharmacology

Directory of Open Access Journals (Sweden)

Zvi Ioav Cabantchik

2014-03-01

Full Text Available In living systems iron appears predominantly associated with proteins, but can also be detected in forms referred as labile iron, which denotes the combined redox properties of iron and its amenability to exchange between ligands, including chelators. The labile cell iron (LCI composition varies with metal concentration and substances with chelating groups but also with pH and the redox potential. Although physiologically in the lower µM range, LCI plays a key role in cell iron economy as cross-roads of metabolic pathways. LCI levels are continually regulated by an iron-responsive machinery that balances iron uptake versus deposition into ferritin. However, LCI rises aberrantly in some cell types due to faulty cell utilization pathways or infiltration by pathological iron forms that are found in hemosiderotic plasma. As LCI attains pathological levels, it can catalyze reactive O species (ROS formation that, at particular threshold, can surpass cellular anti-oxidant capacities and seriously damage its constituents. While in normal plasma and interstitial fluids, virtually all iron is securely carried by circulating transferrin (that renders iron essentially non-labile, in systemic iron overload (IO, the total plasma iron binding capacity is often surpassed by a massive iron influx from hyperabsorptive gut or from erythrocyte overburdened spleen and/or liver. As plasma transferrin approaches iron saturation, labile plasma iron (LPI emerges in forms that can infiltrate cells by unregulated routes and raise LCI to toxic levels. Despite the limited knowledge available on LPI speciation in different types and degrees of iron overload, LPI measurements can be and are in fact used for identifying systemic IO and for initiating/adjusting chelation regimens to attain full-day LPI protection. A recent application of labile iron assay is the detection of labile components in iv iron formulations per se as well as in plasma (LPI following parenteral iron

A comparison of the toluene distillation and vacuum/heat methods for extracting soil water for stable isotopic analysis

Science.gov (United States)

Ingraham, Neil L.; Shadel, Craig

1992-12-01

Hanford Loam, from Richland, Washington, was used as a test soil to determine the precision, accuracy and nature of two methods to extract soil water for stable isotopic analysis: azeotropic distillation using toluene, and simple heating under vacuum. The soil was oven dried, rehydrated with water of known stable isotopic compositions, and the introduced water was then extracted. Compared with the introduced water, initial aliquots of evolved water taken during a toluene extraction were as much as 30 ‰ more depleted in D and 2.7 ‰ more depleted in 18O, whereas final aliquots were as much as 40 ‰ more enriched in D and 14.3 ‰ more enriched in 18O. Initial aliquots collected during the vacuum/heat extraction were as much as 64 ‰ more depleted in D and 8.4 ‰ more depleted in 18O than was the introduced water, whereas the final aliquots were as much as 139 ‰ more enriched in D, and 20.8 ‰ more enriched in 18O. Neither method appears quantitative; however, the difference in stable isotopic composition between the first and last aliquots of water extracted by the toluene method is less than that from the vacuum/heat method. This is attributed to the smaller fractionation factors involved with the higher average temperatures of distillation of the toluene. The average stable isotopic compositions of the extracted water varied from that of the introduced water by up to 1.4 ‰ in δD and 4.2 ‰ in δ18O with the toluene method, and by 11.0 ‰ in δD and 1.8 ‰ in δ18O for the vacuum/heat method. The lack of accuracy of the extraction methods is thought to be due to isotopic fractionation associated with water being weakly bound (not released below 110°C) in the soil. The isotopic effect of this heat-labile water is larger at low water contents (3.6 and 5.2% water by weight) as the water bound in the soil is a commensurately larger fraction of the total. With larger soilwater contents the small volume of water bound with an associated fractionation is

Use of I-131 labeled, murine Fab against a high molecular weight antigen of human melanoma: Preliminary experience

International Nuclear Information System (INIS)

Larson, S.M.; Carrasquillo, J.A.; McGuffin, R.W.

1985-01-01

High molecular-weight antigen (HMWA) is tumor-associated proteoglycan of human malignant melanoma. I-131 labeled Fab fragments of these specific antibodies were used for preliminary feasibility studies for radioimmunodetection and therapy of human subjects who had inoperable metastatic melanoma. Ten patients received tracer doses of I-131 (anti-HMWA) Fab. All patients (8/8) who had melanoma lesions greater than 1 cm by correlative diagnosis methods had one or more lesions that had localization to tumor of the radiolabelled Fab. In all, 17 of 23 (74%) documented metastases were seen. Two patients who had avid uptake received potentially radiotherapeutic doses. For both of these patients, whole imaging studies showed that the localization of the high dose I-131 Fab was predominantly in tumor. On whole body images, the anti-Fab HMWA appears to be more tumor selective than Fab preparations that target the p97 antigen for melanoma, and there is less uptake in liver

Structure characterization of the central repetitive domain of high molecular weight gluten proteins. II. Characterization in solution and in the dry state

OpenAIRE

Dijk, Alard A. van; Boef, Esther de; Bekkers, August; Wijk, Lourens L. van; Swieten, Eric van; Hamer, Rob J.; Robillard, George T.

1997-01-01

The structure of the central repetitive domain of high molecular weight HMW) wheat gluten proteins was characterized in solution and in the dry state using HMW proteins Bx6 and Bx7 and a subcloned, bacterially expressed part of the repetitive domain of HMW Dx5. Model studies of the HMW consensus peptides PGQGQQ and GYYPTSPQQ formed the basis for the data analysis (van Dijk AA et al., 1997, Protein Sci 6:637-648). In solution, the repetitive domain contained a continuous nonoverlapping series ...

Molecular weight determination of bisbenzyl-isoquinoline alkaloids by 252Cf-plasma desorption mass spectrometer

International Nuclear Information System (INIS)

Kohno, Hiroyuki; Tatsunami, Shinobu; Hiroi, Tomoko; Kouyama, Hiroshi; Taniguchi, Masashi; Yago, Nagasumi; Nakamura, Iwao

1995-01-01

Bisbenzylisoquinoline alkaloids of Stephania cepharantha have been used for various clinical purposes and recently reevaluated as stimulators of interleukin secretion in tissues. We analyzed molecular stuctures of bisbenzylisoquinoline alkaloids by determining their molecular weights using the 252 Cf-plasma desorption mass spectrometry (PDMS). The spectra were accumulated for 500 000 fission events. The acceleration voltage used here was 15 kV. Samples were analyzed using nitrocellulose-coated sample targets. Of the 5 alkaloids studied here, cepharanthine gave a main peak of molecular weight of 606.1 for the theoretical molecular weight of 606.7. The other minor peaks were considered to be demethylated fragment ions. 252 Cf-PDMS should be quite useful in studying structure, metabolism and pharmacokinetics of various drugs with extremely low coefficients of variation. (author)

Double-blind, placebo-controlled immunotherapy with mixed grass-pollen allergoids. IV. Comparison of the safety and efficacy of two dosages of a high-molecular-weight allergoid.

Science.gov (United States)

Bousquet, J; Hejjaoui, A; Soussana, M; Michel, F B

1990-02-01

Specific immunotherapy is still widely used in grass-pollen allergy, but its side effects may limit its use. We tested the safety and efficacy of a formalinized high-molecular-weight allergoid prepared from a mixed grass-pollen extract with two injection schedules in a double-blind, placebo-controlled study. Eighteen patients received placebo, 19 received the low-dose schedule (maximal dose: 2000 PNU) and 20 received the high-dose schedule (maximal dose: 10,000 PNU). Only one patient presented a systemic reaction of moderate severity for a dose of 1200 PNU. Before the onset of the pollen season, patients had a nasal challenge with orchard grass-pollen grains, a skin test titration, and the titration of serum-specific IgG. Both groups of patients presented a significant reduction in nasal and skin sensitivities and a significant increase in IgG compared to placebo. Symptoms and medications for rhinitis and asthma were studied during the season, and both groups receiving allergoids had a significant reduction of symptom-medication scores for nasal and bronchial symptoms. There was a highly significant correlation between nasal symptom-medication scores during the season and the results of nasal challenges. High-molecular-weight allergoids are safe and effective.

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

Directory of Open Access Journals (Sweden)

R. J. Waltman

2012-01-01

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

Controlling the Molecular Weight of Lignosulfonates by an Alkaline Oxidative Treatment at Moderate Temperatures and Atmospheric Pressure: A Size-Exclusion and Reverse-Phase Chromatography Study

Directory of Open Access Journals (Sweden)

Chamseddine Guizani

2017-11-01

Full Text Available The molecular weights of lignosulfonates (LSs are modified by a rather simple process involving an alkaline oxidative treatment at moderate temperatures (70–90 °C and atmospheric pressure. Starting from LSs with an average molecular weight of 90,000 Da, and using such a treatment, one can prepare controlled molecular weight LSs in the range of 30,000 to 3500 Da based on the average mass molecular weight. The LS depolymerisation was monitored via reverse-phase and size-exclusion chromatography. It has been shown that the combination of O2, H2O2 and Cu as a catalyst in alkaline conditions at 80 °C induces a high LS depolymerisation. The depolymerisation was systemically accompanied by a vanillin production, the yields of which reached 1.4 wt % (weight percentage on LS raw basis in such conditions. Also, the average molecular weight and vanillin concentration were correlated and depended linearly on the temperature and reaction duration.

Antipsychotics and physical attractiveness.

Science.gov (United States)

Seeman, Mary V

2011-10-01

Antipsychotics are effective in treating the symptoms of schizophrenia, but they may induce adverse effects, some of which-those that impact negatively on physical appearance-have not been sufficiently discussed in the psychiatric literature. Through a narrative review, to catalog antipsychotic side effects that interfere with physical attractiveness and to suggest ways of addressing them. PubMed databases were searched for information on the association between "antipsychotic side effects" and "attractiveness" using those two search phrases plus the following terms: "weight," "teeth," "skin," "hair," "eyes," "gait," "voice," "odor." Data from relevant qualitative and quantitative articles were considered, contextualized, and summarized. Antipsychotics, as a group, increase weight and may lead to dry mouth and bad breath, cataracts, hirsutism, acne, and voice changes; they may disturb symmetry of gait and heighten the risk for tics and spasms and incontinence, potentially undermining a person's attractiveness. Clinicians need to be aware of the impact of therapeutic drugs on appearance and how important this issue is to patients. Early in treatment, they need to plan preventive and therapeutic strategies.

A 2 Tesla Full Scale High Performance Periodic Permanent Magnet Model for Attractive (228 KN) and repulsive Maglev

Science.gov (United States)

Stekly, Z. J. J.; Gardner, C.; Domigan, P.; Baker, J.; Hass, M.; McDonald, C.; Wu, C.; Farrell, R. A.

1996-01-01

Two 214.5 cm. long high performance periodic (26 cm period) permanent magnet half-assemblies were designed and constructed for use as a wiggler using Nd-B-Fe and vanadium permendur as hard and soft magnetic materials by Field Effects, a division of Intermagnetics General Corporation. Placing these assemblies in a supporting structure with a 2.1 cm pole to pole separation resulted in a periodic field with a maximum value of 2.04 T. This is believed to be the highest field ever achieved by this type of device. The attractive force between the two 602 kg magnet assemblies is 228 kN, providing enough force for suspension of a 45,500 kg vehicle. If used in an attractive maglev system with an appropriate flat iron rail, one assembly will generate the same force with a gap of 1.05 cm leading to a lift to weight ratio of 38.6, not including the vehicle attachment structure. This permanent magnet compares well with superconducting systems which have lift to weight ratios in the range of 5 to 10. This paper describes the magnet assemblies and their measured magnetic performance. The measured magnetic field and resulting attractive magnetic force have a negative spring characteristic. Appropriate control coils are necessary to provide stable operation. The estimated performance of the assemblies in a stable repulsive mode, with eddy currents in a conducting guideway, is also discussed.