Temperature dependent measurements on a low-molecular-weight photorefractive glass

2002 ◽  
Author(s):  
Ralf Bausinger ◽  
Andre Leopold ◽  
Stephan J. Zilker ◽  
Dietrich Haarer ◽  
Jolita Ostrauskaite ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
Temperature Dependent

Possible Mechanisms for the Increase in Alkaline Phosphatase Activity of Lyophilized Control Material

1972 ◽  
Vol 18 (12) ◽  
pp. 1518-1523 ◽  
Author(s):  
Alistair F Smith ◽  
Barbara A Fogg
Keyword(s):  
Molecular Weight ◽  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Gel Filtration ◽  
Low Molecular Weight ◽  
Temperature Dependent ◽  
Control Material ◽  
Rate Of Increase ◽  
Control Procedures

Abstract The increased alkaline phosphatase (EC 3.1.3.1) activity of reconstituted lyophilized control sera has recently been the focus of considerable interest because of its possible implications for quality-control procedures. We confirm that these reconstituted materials show a temperature-dependent increase in alkaline phosphatase activity, but could show no alteration in activity of fresh sera. The rate of increase in activity was unaffected by dialysis of the reconstituted material, and occurred more rapidly in dilute solutions. Studies with acrylamide gel electrophoresis and Sephadex G-200 gel filtration showed that, immediately after reconstitution, a high-molecular-weight alkaline phosphatase component predominated; during subsequent spontaneous activation this component decreased, and there was a concomitant increase in a low-molecular-weight alkaline phosphatase component. The results obtained when the reconstituted material was extracted with butanol suggest that the observed changes in alkaline phosphatase activity may be attributed to the breakdown of a complex between alkaline phosphatase and lipoprotein.

Bonding of Butyl and Nitrile Rubber by in situ Copolymer Formation

1989 ◽  
Vol 62 (2) ◽  
pp. 367-385 ◽  
Author(s):  
M. H. Chung ◽  
G. R. Hamed
Keyword(s):  
Molecular Weight ◽  
Peel Strength ◽  
Low Molecular Weight ◽  
Temperature Dependent ◽  
Wlf Equation ◽  
Test Speed ◽  
Strong Adhesion ◽  
Peel Adhesion ◽  
Dependent Failure

Abstract We summarize and conclude the following: 1. The T-peel adhesion between uncrosslinked layers of IIR and NBR is rate and temperature dependent. Failure is interfacial at low rates; bulk cohesive tearing of the rubber occurs at intermediate rates, while interfacial failure returns at high rates. 2. Adhesion data could be reduced to mastercurves with experimentally determined shift factors which were in reasonable agreement with those calculated from the universal WLF equation with a Tg=−69°C. 3. At the lowest test rates, peel specimens containing in situ-formed copolymer had lower strength than those without the copolymer. This is probably due to the easy slippage of the segments of the low-molecular-weight copolymer in this regime. 4. At intermediate rates, in situ copolymer had no effect on peel strength; specimens failed by bulk cohesive tearing of rubber, whether or not the copolymer was present. 5. At high rates, peel specimens containing the copolymer exhibited improved strengths. The behavior is consistent with previous results on the autohesion of elastomers. Interdiffused chains of relatively low molecular weight are only capable of providing strong adhesion when the test speed is sufficiently rapid.

Temperature Dependent Studies of Molecular Interactions in a Low-Molecular Weight Ester Diol Mixed with a Hyperbranched Polyester Additive

2003 ◽  
Vol 204 (10) ◽  
pp. 1275-1283 ◽  
Author(s):  
Antje Ziemer ◽  
Klaus-Jochen Eichhorn ◽  
Gudrun Adam ◽  
Christian Froeck ◽  
Brigitte Voit ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Molecular Interactions ◽  
Low Molecular Weight ◽  
Hyperbranched Polyester ◽  
Temperature Dependent

scholarly journals The Genetics of Heat Shock Proteins in Wheat in Relation to Heat Tolerance and Yield

1993 ◽  
Author(s):  
Abraham Blum ◽  
Henry T. Nguyen ◽  
N.Y. Klueva
Keyword(s):  
Molecular Weight ◽  
Genetic Variation ◽  
Heat Stress ◽  
Heat Shock ◽  
Full Range ◽  
F1 Hybrids ◽  
Low Molecular Weight ◽  
Temperature Dependent ◽  
Winter Conditions ◽  
Ril Population

Fifty six diverse spring wheat cultivars were evaluated for genetic variation and heritability for thermotolerance in terms of cell-membrane stability (CMS) and triphenyl tetrazolium chloride (TTC) reduction. The most divergent cultivars for thermotolerance (Danbata-tolerant and Nacozari-susceptible) were crossed to develop an F8 random onbred line (RIL) population. This population was evaluated for co-segragation in CMS, yield under heat stress and HSP accumulation. Further studies of thermotolerance in relations to HSP and the expression of heterosis for growth under heat stress were performed with F1 hybrids of wheat and their parental cultivars. CMS in 95 RILs ranged from 76.5% to 22.4% with 71.5% and 31.3% in Danbata and Nacozari, respectively. The population segregated with a normal distribution across the full range of the parental values. Yield and biomass under non-stress conditions during the normal winter season at Bet Dagan dit not differ between the two parental cultivar, but the range of segregation for these traits in 138 RILs was very high and distinctly transgressive with a CV of 35.3% and 42.4% among lines for biomass and yield, respectively. Mean biomass and yield of the population was reduced about twofold when grown under the hot summer conditions (irrigated) at Bet Dagan. Segregation for biomass and yield was decreased relative to the normal winter conditions with CV of 20.2% and 23.3% among lines for biomass and yield, respectively. However, contrary to non-stress conditions, the parental cultivars differed about twofold in biomass and yield under heat stress and the population segregated with normal distribution across the full range of this difference. CMS was highly and positively correlated across 79 RILs with biomass (r=0.62**) and yield (r=0.58**) under heat stress. No such correlation was obtained under the normal winter conditions. All RILs expressed a set of HSPs under heat shock (37oC for 2 h). No variation was detected among RILs in high molecular weight HSP isoforms and they were similar to the patterns of the parental cultivars. There was a surprisingly low variability in low molecular weight HSP isoforms. Only one low molecular weight and Nacozari-specific HSP isoform (belonging to HSP 16.9 family) appeared to segregate among all RILs, but it was not quantitatively correlated with any parameter of plant production under heat stress or with CMS in this population. It is concluded that this Danbata/Nacozari F8 RIL population co-segregated well for thermotolerance and yield under heat stress and that CMS could predict the relative productivity of lines under chronic heat stress. Regretfully this population did not express meaningful variability for HSP accumulation under heat shock and therefore no role could be seen for HSP in the heat tolerance of this population. In the study of seven F1 hybrids and their parent cultivars it was found that heterosis (superiority of the F1 over the best parent) for CMs was generally lower than that for growth under heat stress. Hybrids varied in the rate of heterosis for growth at normal (15o/25o) and at high (25o/35o) temperatures. In certain hybrids heterosis for growth significantly increased at high temperature as compared with normal temperature, suggesting temperature-dependent heterosis. Generally, under normal temperature, only limited qualitative variation was detected in the patterns of protein synthesis in four wheat hybrids and their parents. However, a singular protein (C47/5.88) was specifically expressed only in the most heterotic hybrid at normal temperature but not in its parent cultivars. Parental cultivars were significantly different in the sets of synthesized HSP at 37o. No qualitative changes in the patterns of protein expression under heat stress were correlated with heterosis. However, a quantitative increase in certain low molecular weight HSP (mainly H14/5.5 and H14.5.6, belonging to the HSP16.9 family) was positively associated with greater heterosis for growth at high temperature. None of these proteins were correlated with CMS across hybrids. These results support the concept of temperature-dependent heterosis for growth and a possible role for HSP 16.9 family in this respect. Finally, when all experiments are viewed together, it is encouraging to find that genetic variation in wheat yield under chronic heat stress is associated with and well predicted by CMS as an assay of thermotolerance. On the other hand the results for HSP are elusive. While very low genetic variation was expressed for HSP in the RIL population, a unique low molecular weight HSP (of the HSP 16.9 family) could be associated with temperature dependant heterosis for growth.

scholarly journals A novel relationship between O-antigen variation, matrix formation, and invasiveness ofSalmonella enteritidis

1996 ◽  
Vol 117 (2) ◽  
pp. 219-231 ◽  
Author(s):  
J. Guard-Petter ◽  
L. H. Keller ◽  
M. Mahbubur Rahman ◽  
R. W. Carlson ◽  
S. Silvers
Keyword(s):  
Molecular Weight ◽  
Cell Surface ◽  
Cross Reactivity ◽  
Surface Proteins ◽  
Low Molecular Weight ◽  
Temperature Dependent ◽  
O Antigen ◽  
Oral Inoculation ◽  
Dependent Cell ◽  
35 Kda Protein

SummarySalmonella entericaEnteritidis in chickens serves as a reservoir for salmonellosis in humans and the structure of its lipopolysaccharide (LPS) has been used to assess invasiveness. Culture from chick spleens generated colonies with an unusual wrinkled morphology, and it is designated the lacy phenotype. To characterize the nature of the morphological change, three isogenic variants were compared. Only the lacy phenotype produced a temperature-dependent cell surface matrix composed of several proteins in association with LPS high molecular weight O-antigen.Flagellin and a 35 kDa protein were identified as specific proteinaceous components of matrix. Both proteins cross-reacted with a monoclonal antibody previously determined to specifically detect the g-epitope of the Enteritidis monophasic flagella (H-antigen). These results suggest that O-antigen in association with protein contributes to cross-reactivity between molecules. The lacy phenotype was more organ invasive in 5-day-old chicks than isogenic variants producing low molecular weight O-antigen. However, it was no more efficient at contaminating eggs after oral inoculation of hens than a variant that completely lacked O-antigen, thus the lacy phenotype is classified as an intermediately invasive organism. The distinctive colonial phenotype of SE6-E21lacywas used to investigate environmental factors that decreased O/C ratios and contributed to attenuation. In so doing, it was found that growth in complement at 46°C caused matrix producing cells to hyperflagellate and migrate across agar surfaces. These results suggest that the structure of O-antigen might influence the secretion and/or the function of Enteritidis cell-surface proteins. The data also reveal a greater heterogeneity than has been assumed in the phenotype, and possibly the infectious behaviour, of Enteritidis.

A high-performance oil-free backing pump for electron microscopes

1978 ◽  
Vol 36 (1) ◽  
pp. 110-111
Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Hot Spots ◽  
High Performance ◽  
Carbonaceous Material ◽  
Contamination Rate ◽  
Low Molecular Weight ◽  
Principal Source ◽  
Rotary Pumps ◽  
Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

Low-molecular-weight heparin in the prevention and treatment of thromboembolic disorders

1998 ◽  
Vol 1 (5) ◽  
pp. 166-174 ◽  
Author(s):  
Evelyn R Hermes De Santis ◽  
Betsy S Laumeister ◽  
Vidhu Bansal ◽  
Vandana Kataria ◽  
Preeti Loomba ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Low Molecular Weight ◽  
Prevention And Treatment
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