Total-molecular-weight-dependent Rouse dynamic of ultra-small branched star poly(ε-caprolactone)s as a single coarse-grain unit

Polymer ◽  
2015 ◽  
Vol 79 ◽  
pp. 91-98 ◽  
Author(s):  
Woohyuk Choi ◽  
Jae Woo Chung ◽  
Seung-Yeop Kwak
Keyword(s):  
Molecular Weight ◽  
Coarse Grain ◽  
Total Molecular Weight ◽  
Grain Unit

scholarly journals Crotalase, a Fibrinogen-Clotting Snake Venom Enzyme: Primary Structure and Evidence for a Fibrinogen Recognition Exosite Different from Thrombin

1999 ◽  
Vol 81 (01) ◽  
pp. 81-86 ◽  
Author(s):  
Agnes Henschen-Edman ◽  
Ida Theodor ◽  
Brian Edwards ◽  
Hubert Pirkle
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Spatial Modeling ◽  
Glycosylation Site ◽  
Amino Sugars ◽  
Edman Degradation ◽  
Heparin Binding ◽  
Heparin Binding Site ◽  
Total Molecular Weight

SummaryCrotalase, a fibrinogen-clotting enzyme isolated from the venom of Crotalus adamanteus, and its overlapping fragments were subjected to Edman degradation. The resulting amino acid sequence, VIGGDEC NINEHRFLVALYDYWSQLFLCGGTLINNEWVLTAAHCDRTHI LIYVGVHDRSVQFDKEQRRFPKEKYFFDCSNNFTKWDKDIM LIRLNKPVSYSEHIAPLSLPSSPPIVGSVCRAMGWGQTTSPQET LPDVPHCANINLLDYEVCRTAHPQFRLPATSRTLCAGVLEG GIDTCNRDSGGPLICNGQFQGIVFWGPDPCAQPDKPGLYTK VFDHLDWIQSIIAGEKTVNCP, is characteristic of a serine protein-ase. Comparison with thrombin, the physiological fibrinogen-clotting enzyme, showed that thrombin’s fibrinogen-recognition exosite (FRE) is poorly represented in crotalase. Hirudin, a FRE-dependent inhibitor, had no effect on crotalase. Spatial modeling of crotalase yielded a possible alternative fibrinogen-recognition site comprised of Arg 60F, Lys 85, Lys 87, and Arg 107 (underlined in the sequence above). Crotalase also lacks thrombin’s YPPW loop, as well as its functionally important ETW 146-148, and its heparin-binding site. The enzyme contains a single asparagine-linked glycosylation site, NFT, bearing neutral and amino sugars that account for 8.3% of the enzyme’s total molecular weight of 29,027. The calculated absorbance of crotalase at 280 nm, 1%, cm-1is 15.2.

scholarly journals Poly(lactic acid) polymer stars built from early generation dendritic polyols

2013 ◽  
Vol 91 (6) ◽  
pp. 392-397 ◽  
Author(s):  
Genny E. Keefe ◽  
Jean-d'Amour K. Twibanire ◽  
T. Bruce Grindley ◽  
Michael P. Shaver
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Gel Permeation Chromatography ◽  
Poly Lactic Acid ◽  
Reactive Site ◽  
Scanning Calorimetry ◽  
Early Generation ◽  
Sequential Reaction ◽  
Cyclic Esters ◽  
Total Molecular Weight

A family of polymer stars has been prepared from early generation dendritic cores with four, six, and eight arms. Four dendritic cores were prepared from the sequential reaction of a multifunctional alcohol with a protected anhydride, followed by deprotection to afford two or three new alcohol functionalities per reactive site. These cores were used as initiators for the tin-catalyzed ring-opening polymerization of l-lactide and rac-lactide to afford isotactic and atactic degradable stars, respectively. Two series of stars were prepared for each monomer, either maintaining total molecular weight or number of monomer units per arm. The polymers were characterized by NMR spectroscopy, light-scattering gel-permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. Our results support previous work that suggests that the length of the arms dictates thermal properties rather than the total molecular weight of the star. Little effect was noted between aromatic and aliphatic cores, presumably due to the flexibility of the rest of the core molecule. We have shown that early generation dendrimers can serve as excellent core structures for building core-first polymer stars via the ring-opening of cyclic esters.

The Morphology of Symietric Diblock Copolymers as Revealed by Neutron Reflectivity

1989 ◽  
Vol 166 ◽  
Author(s):  
S. K. Satija ◽  
C. F. Majkrzak ◽  
S. H. Anastasiadis ◽  
T. P. Russell
Keyword(s):  
Molecular Weight ◽  
Concentration Gradient ◽  
Diblock Copolymers ◽  
Neutron Reflectivity ◽  
Effective Width ◽  
Hyperbolic Tangent ◽  
A Value ◽  
Specular Reflectivity ◽  
Tangent Function ◽  
Total Molecular Weight

ABSTRACTThe specular reflectivity of neutrons has been used to characterize quantitatively the microphase separated morphology of symmetric, diblock copolymers of polystyrene, PS and polymethylmethacrylate, PMMA, as a function of the total molecular weight of the copolymer where either block is perdeuterated. It is shown that the hyperbolic tangent function, as opposed to a linear or cosine squared function, most closely describes the concentration gradient at the interface between the lamellar copolymer microdomains. The effective width of the interface is found to be independent of the molecular weight of the copolymer blocks and has a value of 50 ± 3Å. This interface is also found to be identical to that of PS and PMMA, homopolymers. However, using measured values of the Flory-Huggins interaction parameter for PS and PMMA current theoretical treatments cannot describe the observed widths of the interface.

scholarly journals Properties Change of Korean Traditional Animal Glue Depending on The Parts of Cattle Hide and Extraction Conditions

2021 ◽  
Vol 37 (5) ◽  
pp. 557-566
Author(s):  
Gyu Hyuk Cho ◽  
Ji Sun Choi ◽  
Dea Woo Park ◽  
Han Hyoung Lee ◽  
Yong Jea Chung
Keyword(s):  
Molecular Weight ◽  
Triple Helix ◽  
Average Molecular Weight ◽  
Extraction Time ◽  
Animal Glue ◽  
Helix Structure ◽  
Average Change ◽  
Total Molecular Weight ◽  
Different Parts ◽  
Over Time

We investigated the properties of Korean traditional animal glue which are associated with the use of different parts of cattle hide and extraction conditions. Both average molecular weight(Mw, Mz) and polydispersity (PDI) of the animal glue increased with extraction time, whereas only PDI decreased after 48h. There were no differences in the average molecular weight and PDI for the different cattle hide parts used, although a individual difference was observed with regard to total molecular weight. Differences in extracts over time were compared by investigating the amide regions representing the gelatien component of the animal glue. The triple helix structure of the belly skin deteriorated in a manner proportional to the extraction time, and differences were observed for each cattle hide part. The yellowness increased with the extraction time; however, the viscosity was not proportional to the average change in molecular weight. This study has some limitations because of difficulties in the quality control of cases where small amounts of glue were extracted as small differences might impact the overall results considerably. Further research exploring various extraction conditions is required to ensure the prodiction of traditional animal glue with optimum qualities.

Reactions of thiyl radicals. XIII. Photochemically induced exchange reactions of liquid alkyl disulfides

1980 ◽  
Vol 58 (13) ◽  
pp. 1350-1354 ◽  
Author(s):  
Dinesh Gupta ◽  
Arthur R. Knight
Keyword(s):  
Molecular Weight ◽  
Product Formation ◽  
Quantum Yields ◽  
Light Sources ◽  
Thiyl Radical ◽  
Exchange Reactions ◽  
Thiyl Radicals ◽  
Steric Factors ◽  
Total Molecular Weight ◽  
Symmetrical Disulfide

The liquid phase photolysis of some 35 liquid alkyl disulfide mixtures has been studied. The corresponding unsymmetrical disulfide is the only significant product of the reaction and the System attains a photo-equilibrium state at longer exposure times. Product formation is completely eliminated by the addition of nitric oxide.Quantum yields have been redetermined for the methyl disulfide – ethyl disulfide System using four different light sources. Initial rates have been measured for each of the 35 combinations and have been shown to be a function of total molecular weight of the disulfide mixture and to be strongly influenced by steric factors. These effects are most pronounced for mixtures wherein the exchange reaction between thiyl radical and a symmetrical disulfide is important as indicated by quantum yields above unity. Combinations of isodisulfides give rise to anomalously high rates.

Steady Flow and Dynamic Viscosity of Branched Butadiene-Styrene Block Copolymers

1972 ◽  
Vol 45 (4) ◽  
pp. 1005-1014
Author(s):  
G. Kraus ◽  
F. E. Naylor ◽  
K. W. Rollmann
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Block Copolymers ◽  
Steady Flow ◽  
Domain Structure ◽  
Viscoelastic Behavior ◽  
Significant Degree ◽  
Two Phase ◽  
Total Molecular Weight ◽  
Block Structures

Abstract Steady flow and dynamic viscosities were determined for symmetrical linear and star-branched block copolymers of butadiene and styrene above their upper (polystyrene) glass transition. Block structures examined were B-S-B, (B-S-)3, S-B-S, (S-B-)3 and (S-B-)4. At constant molecular weight and total styrene content viscosities were greater for polymers terminating in styrene blocks, irrespective of branching. Branching decreased the viscosity of either polybutadiene-terminated or polystyrene-terminated block polymers, compared at equal Mw. However, comparisons at equal block lengths showed that the length of the terminal blocks, not the total molecular weight, governs the viscoelastic behavior of these polymers to a surprisingly good approximation. This unusual result is rationalized in terms of the two-phase domain structure of these polymers, which persists to a significant degree in the melt. Below the glass transition of the polystyrene blocks the effects of branching were masked by differences in the morphology of the domain structure unrelated to branching.

Formation of 12-nm Nanodot Pattern by Block Copolymer Self-Assembly Technique

2011 ◽  
Vol 497 ◽  
pp. 122-126 ◽  
Author(s):  
Miftakhul Huda ◽  
Takuro Tamura ◽  
You Yin ◽  
Sumio Hosaka
Keyword(s):  
Molecular Weight ◽  
Quantum Dot ◽  
Self Assembly ◽  
Microphase Separation ◽  
Experimental Result ◽  
Storage Device ◽  
Pdms Layer ◽  
Pdms Film ◽  
Assembly Technique ◽  
Total Molecular Weight

In this work, we studied the fabrication of 12-nm-size nanodot pattern by self-assembly technique using high-etching-selectivity poly (styrene)-poly (dimethyl-siloxane) (PS-PDMS) block copolymers. The necessary etching duration for removing the very thin top PDMS layer is unexpectedly longer when the used molecular weight of PS-PDMS is 13.5-4.0 kg/mol (17.5 kg/mol total molecular weight) than that of 30.0-7.5 kg/mol (37.5 kg/mol total molecular weight). From this experimental result, it was clear that PS-PDMS with lower molecular weight forms thicker PDMS layer on the air/polymer interface of PS-PDMS film after microphase separation process. The 22-nm pitch of nanodot pattern by self-assembly holds the promise for the low-cost and high-throughput fabrication of 1.3 Tbit/inch2storage device. Nanodot size of 12 nm also further enhances the quantum-dot effect in quantum-dot solar cell.

Weitere Charakterisierung einer Chlorogensäure-Hydrolase aus Aspergillus niger / Further Characterization of a Chlorogenic Acid Hydrolase from Aspergillus niger

1980 ◽  
Vol 35 (9-10) ◽  
pp. 699-701 ◽  
Author(s):  
B. Schöbel ◽  
W. Pollmann
Keyword(s):  
Activation Energy ◽  
Molecular Weight ◽  
Aspergillus Niger ◽  
Chlorogenic Acid ◽  
Sodium Dodecyl ◽  
Acid Hydrolase ◽  
Ester Linkage ◽  
Total Molecular Weight ◽  
Ph Range

Abstract In addition to our previous paper [1] further characteristics of the chlorogenic acid hydrolase are described. Polyacrylamid gelelectrophoresis revealed only one band for the purified enzyme. Sodium dodecyl-sulfate polyacrylamid gelelectrophoresis showed a molecular weight of 60000, demonstrating four subunits of the enzyme (total molecular weight 240000). The enzyme is stable in a pH-range of 3 .0 -8 .5 and up to a temperature of 55 °C. The temperature coefficient Q10 is 1.5, the activation energy EA is 6.0 kcal/mol. The amino acid analysis and substrate specificity data are given in tables. Essential for the enzyme activity is the C=C double bound neighbouring the ester linkage. The enzyme crystallizes in prisms.

Biomonitoring of polycyclic aromatic hydrocarbons on hepatocellular carcinoma cell line

2005 ◽  
Vol 52 (9) ◽  
pp. 219-224 ◽  
Author(s):  
S. Seker ◽  
K. Arakawa ◽  
M. Sekiguchi ◽  
Y. Ono
Keyword(s):  
Hepatocellular Carcinoma ◽  
Molecular Weight ◽  
Aromatic Hydrocarbons ◽  
Carcinoma Cell ◽  
Erod Activity ◽  
Sediment Samples ◽  
Polycyclic Aromatic ◽  
Hepatocellular Carcinoma Cell Line ◽  
Hepatocellular Carcinoma Cell ◽  
Total Molecular Weight

Polycyclic aromatic hydrocarbons (PAHs) are not easily degradable and exist as persistent contaminants in water environments. In this study we collected surface sediments and water samples from five different ports around Seto Inland Sea during October 2003 to April 2004. Fifteen PAHs were detected by gas chromatography/mass spectrometer (GC-MS). Expression of CYP1A enzymes was measured by a biochemical activation of 7-ethoxy resorufin ortho-deethylase (EROD). Total water PAHs ranged from 2.5ng/l to 132ng/l, while sediment PAHs ranged from 296.3ng/g to 3992.9ng/g, which indicate low to high level of PAH pollution. Selected isomer ratios (fluoranthene/pyrene to phenanthrene/anthracene and, total molecular weight of 202/total molecular weight 202–278), and detected PAHs suggested that the origin of pollution could mostly be pyrogenic. The highest total sediment PAHs were observed at the Uno Port while the lowest were at the New Okayama Port. EROD activity implied that PAH extracted from sediment samples affected on CYP1A enzymes expression on the human hepatocellular carcinoma cell line in a short exposure time (12 hours). Relatively EROD activity showed good correlation between PAH concentration and CYP1A expression for sediment samples. The highest EROD values were observed for sediment samples at a dose of 5ppm. In contrast water samples were at the low induction level even under the highest exposure concentration (50ppm), except in Mizushima Port. Biomonitoring of water environments by EROD activity could be a necessary tool for understanding the effects of PAHs on living organisms at the base of cell defense.

LIGHT-SCATTERING STUDIES OF COPOLYMERS: I. EFFECT OF HETEROGENEITY OF CHAIN COMPOSITION ON THE MOLECULAR WEIGHT

1958 ◽  
Vol 36 (12) ◽  
pp. 1616-1626 ◽  
Author(s):  
W. Bushuk ◽  
H. Benoit
Keyword(s):  
Molecular Weight ◽  
Refractive Index ◽  
Light Scattering ◽  
Average Molecular Weight ◽  
Apparent Molecular Weight ◽  
Scattering Data ◽  
Refractive Index Increment ◽  
Molecular Weights ◽  
Chain Composition ◽  
Total Molecular Weight

The classical light-scattering theory for polymer solutions is extended to solutions of copolymers which may be polydisperse in chain composition as well as in molecular weight. It is shown that much too high molecular weights will result from light-scattering data for copolymers owing to fluctuations in chain composition; the magnitude of this effect increases rapidly as the absolute value of the refractive index increment approaches zero. The methods for determining the usual weight-average molecular weight and polydispersity of composition are described.The theory was tested with experimental results on: (1) a mixture of polystyrene and poly(methylmethacrylate), considered as a copolymer with the highest possible polydispersity of composition; (2) a high conversion, statistical copolymer of styrene and methylmethacrylate (copolymer I); and (3) a block copolymer of the same monomers (copolymer II). The apparent molecular weight for copolymer I (Mw = 1.83 × 105) varied markedly with refractive index increment in much the same way as the total molecular weight for the mixture. The molecular weight of copolymer II (Mw = 1.20 × 106) remained essentially constant in the same series of solvents. The polydispersities of composition obtained were 0.72 and 0.05 for copolymer I and II respectively compared with the maximum possible value equal to 1.0.

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