Collapse of a single polystyrene chain in dioctyl phthalate: Effect of molecular weight

1985 ◽  
Vol 50 (11) ◽  
pp. 2579-2587 ◽  
Author(s):  
Petr Štěpánek ◽  
Čestmír Koňák
Keyword(s):  
Molecular Weight ◽  
Linear Function ◽  
Universal Function ◽  
Dioctyl Phthalate ◽  
Dilute Solution ◽  
Expansion Factor ◽  
Temperature Variable ◽  
Factor Α ◽  
Reduced Temperature ◽  
Polymer Region

The use of a viscous solvent (dioctyl phthalate) made possible an investigation of the whole coil-globule transition of polystyrene chains in dilute solution. For values of the reduced temperature variable τ√M lower than - 230 the globular polymer region was observed in which the radius R and the molecular weight M are related by R ~ M1/3. The range of the Θ region where the expansion factor α is a linear function of τ√M was determined as -50 < τ√M < 50. It was shown that within the whole temperature range investigated the expansion factor is a universal function of the variable τ√M. The polymer dimensions at the Θ temperature are higher by some 15% in this solvent than in cyclohexane; also, the width of the transition region is much larger.

Excluded-Volume Effects in Dilute Polymer Solutions. V. Butyl Rubber in Various Solvents

1975 ◽  
Vol 48 (4) ◽  
pp. 765-780
Author(s):  
T. Tsuji ◽  
H. Fujita
Keyword(s):  
Excluded Volume ◽  
Dilute Solution ◽  
Expansion Factor ◽  
Excluded Volume Effects ◽  
Dilute Polymer Solutions ◽  
Composite Curve ◽  
Factor Α ◽  
Fundamental Requirement ◽  
Two Parameter ◽  
Parameter Theory

Abstract It is a fundamental requirement of the two-parameter theory of linear homopolymers in dilute solution that the expansion factor α, and the interpenetration function Ψ depend only on the excluded-volume parameter z and that these functions are universal in the sense that their forms are independent of the chemical nature of the polymer and solvent as well as of the temperature. It follows immediately from the above requirement that the values of Ψ for different combinations of polymer, solvent, and temperature should form a single composite curve when plotted against αs.

Molecular Weight Induced Conformational Change and Its Impact on β-Phase Formation of Polydiarylfluorene in Dilute Solution

2020 ◽  
Vol 124 (11) ◽  
pp. 6304-6310 ◽  
Author(s):  
Masaru Nagai ◽  
Jie Liu ◽  
Wei Huang ◽  
Moriya Kikuchi ◽  
Seigou Kawaguchi ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Conformational Change ◽  
Phase Formation ◽  
Dilute Solution ◽  
Β Phase

Synthesis and Properties of Regular Star Polybutadienes with 32 Arms

1992 ◽  
Vol 65 (2) ◽  
pp. 303-314 ◽  
Author(s):  
L-L. Zhou ◽  
N. Hadjichristidis ◽  
P. M. Toporowski ◽  
J. Roovers
Keyword(s):  
Molecular Weight ◽  
Coupling Agent ◽  
Hard Sphere ◽  
Star Polymers ◽  
Radius Of Gyration ◽  
Linear Polymers ◽  
Solution Properties ◽  
Mean Square ◽  
Dilute Solution ◽  
Dilute Solution Properties

Abstract A dendrimer carbosilane containing 32 Si—Cl bonds in the perimeter has been prepared and has been used as a coupling agent to prepare 32-arm star polybutadienes. The dilute-solution properties 〈RG2〉, A2, [η], and D0 have been measured in one good solvent and in one ¸ -solvent. The dimensions of the 32-arm star polymers are compared with those of linear polymers at constant molecular weight. It is shown that the 32-arm star polybutadiene has the characteristic properties of a hard-sphere molecule in dilute solution. The equivalent hard-sphere radii calculated from A2, D0 and [η] are identical and 1.29 times larger than the root mean-square radius of gyration. The Daoud—Cotton scaling model for stars is also tested.

scholarly journals The breakdown of Darcy's law in a soft porous material

Soft Matter ◽  
2020 ◽  
Vol 16 (4) ◽  
pp. 939-944 ◽  
Author(s):  
Marco Edoardo Rosti ◽  
Satyajit Pramanik ◽  
Luca Brandt ◽  
Dhrubaditya Mitra
Keyword(s):  
Shear Modulus ◽  
Porous Material ◽  
Linear Function ◽  
Pressure Difference ◽  
Darcy’S Law ◽  
Universal Function ◽  
Darcy's Law ◽  
Poroelastic Material

We show that the flux through a poroelastic material is a super-linear function of the pressure-difference. The permeability is a universal function of the ratio of the pressure-difference over the shear modulus, proportional to the cube of porosity.

scholarly journals Immunomodulatory Activity of Low Molecular-Weight Peptides from Nibea japonica in RAW264.7 Cells via NF-κB Pathway

Marine Drugs ◽  
2019 ◽  
Vol 17 (7) ◽  
pp. 404 ◽  
Author(s):  
Zhuangwei Zhang ◽  
Xuyang Hu ◽  
Lin Lin ◽  
Guofang Ding ◽  
Fangmiao Yu
Keyword(s):  
Nitric Oxide ◽  
Molecular Weight ◽  
Cell Cycle Progression ◽  
Protein Hydrolysate ◽  
Raw264.7 Cells ◽  
Immunomodulatory Activity ◽  
Low Molecular Weight ◽  
Phagocytic Capacity ◽  
Activated State ◽  
Factor Α

In this study, a low molecular-weight (Mw) peptide named NJP (<1 kDa), was purified from a protein hydrolysate of Nibea japonica by ultrafiltration, and its immunomodulatory effect on RAW264.7 cells was evaluated. The lactate dehydrogenase (LDH) and MTT assays were performed to explore the cytotoxicity of NJP. The results showed that NJP promoted cell proliferation and had no significant toxic effects on RAW264.7 cells. Moreover, the cells formed multiple pseudopodia indicating that they were in activated state. Further tests showed that NJP significantly promoted phagocytic capacity, and the secretion of proinflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β). It also increased the synthesis of nitric oxide (NO) by upregulating inducible nitric oxide synthase (iNOS) protein level. Flow cytometry revealed that NJP promoted cell cycle progression and increased the percentage of cells in G0/G1 phase. NJP promoted IκBα degradation, p65 and nuclear factor (NF)-κB activation and translocation by up-regulating IKKα/β protein expression. In conclusion, these results indicated that NJP exerts immunomodulatory effects on RAW264.7 cells through the NF-κB signaling pathway. Therefore, NJP can be incorporated in the production of functional foods or nutraceuticals.

Interpretation of long-chain structure from dilute solution properties of ultrahigh molecular weight polymers

1992 ◽  
Vol 27 (5) ◽  
pp. 571-575 ◽  
Author(s):  
Maria Bercea ◽  
Silvia Ioan ◽  
Bogdan C. Simionescu ◽  
Cristofor I. Simionescu
Keyword(s):  
Molecular Weight ◽  
Chain Structure ◽  
Solution Properties ◽  
Dilute Solution ◽  
Dilute Solution Properties ◽  
Ultrahigh Molecular Weight ◽  
Long Chain

scholarly journals MEKK1 activates both IκB kinase α and IκB kinase β

1998 ◽  
Vol 95 (16) ◽  
pp. 9319-9324 ◽  
Author(s):  
Frank S. Lee ◽  
Robert T. Peters ◽  
Luan C. Dang ◽  
Tom Maniatis
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Mitogen Activated Protein Kinase ◽  
Site Specific ◽  
Iκb Kinase ◽  
Mitogen Activated Protein ◽  
Bona Fide ◽  
Factor Α

A critical step in the signal-induced activation of the transcription factor NF-κB is the site-specific phosphorylation of its inhibitor, IκB, that targets the latter for degradation by the ubiquitin–proteasome pathway. We have previously shown that mitogen-activated protein kinase/ERK kinase kinase 1 (MEKK1) can induce both this site-specific phosphorylation of IκBα at Ser-32 and Ser-36 in vivo and the activity of a high molecular weight IκB kinase complex in vitro. Subsequently, others have identified two proteins, IκB kinase α (IKK-α) and IκB kinase β (IKK-β), that are present in a tumor necrosis factor α-inducible, high molecular weight IκB kinase complex. These kinases are believed to directly phosphorylate IκB based on the examination of the kinase activities of IKK immunoprecipitates, but more rigorous proof of this has yet to be demonstrated. We show herein that recombinant IKK-α and IKK-β can, in fact, directly phosphorylate IκBα at Ser-32 and Ser-36, as well as homologous residues in IκBβ in vitro, and thus are bona fide IκB kinases. We also show that MEKK1 can induce the activation of both IKK-α and IKK-β in vivo. Finally, we show that IKK-α is present in the MEKK1-inducible, high molecular weight IκB kinase complex and treatment of this complex with MEKK1 induces phosphorylation of IKK-α in vitro. We conclude that IKK-α and IKK-β can mediate the NF-κB-inducing activity of MEKK1.

Cryoscopy in molten pyridinium chloride

1967 ◽  
Vol 20 (12) ◽  
pp. 2583 ◽  
Author(s):  
H Bloom ◽  
VC Reinsborough
Keyword(s):  
Solid Solution ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
Heat Of Fusion ◽  
Dilute Solution ◽  
Pyridinium Chloride ◽  
Cryoscopic Constant

The molal cryoscopic constant in molten pyridinium chloride (m.p. 146.0�) has been found to be 17.4� (subject to confirmation by calorimetry) and the cryoscopic heat of fusion, 2310�40 cal mole-1. In pyridinium chloride as a solvent, iodides appear to dissociate completely while bromides do not yield the expected depression possibly because of solid solution. Tetraalkylammonium and alkyl-pyridinium halides of high molecular weight are ideally dissociated in extremely dilute solution but with increasing concentration apparently form micelles.

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