THE MOLECULAR WEIGHT OF POLYETHYLENE AND OF OTHER HIGH-MOLECULAR-WEIGHT ORGANIC COMPOUNDS

1958 ◽  
Vol 36 (5) ◽  
pp. 725-730 ◽  
Author(s):  
R. Tremblay ◽  
A. F. Sirianni ◽  
I. E. Puddington
Keyword(s):  
Molecular Weight ◽  
Vapor Pressure ◽  
High Molecular Weight ◽  
Organic Compounds ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Temperature Range ◽  
Molecular Weights ◽  
Pressure Lowering ◽  
Good Agreement

The temperature range of the measurement of vapor-pressure depression using a sensitive differential mercury micromanometer has been extended, and the behavior of a series of polyethylene samples having a molecular-weight range of 2500 to 24,000 was examined in toluene solutions at 75 °C. Good agreement was obtained between vapor-pressure lowering and other means of determining number-average molecular weights of several special compounds.

THE MOLECULAR WEIGHT OF POLYVINYL ACETATE

1958 ◽  
Vol 36 (3) ◽  
pp. 543-549 ◽  
Author(s):  
A. F. Sirianni ◽  
R. Tremblay ◽  
I. E. Puddington
Keyword(s):  
Molecular Weight ◽  
Vapor Pressure ◽  
Polyvinyl Acetate ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Molecular Weights ◽  
Approximate Molecular Weight ◽  
Low Degrees ◽  
Made In

The molecular weights of a series of unfractionated polyvinyl acetates of low degrees of polymerization have been measured by determining the lowering of the vapor pressure of their solutions. An approximate molecular-weight range of 5000–40,000 was examined. While most of the determinations were made in benzene solutions at 55 °C., other solvents and temperatures were used. Anomalous results were obtained with one sample of fractionated material.

scholarly journals THE DETERMINATION OF MOLECULAR WEIGHT

1955 ◽  
Vol 33 (5) ◽  
pp. 755-762 ◽  
Author(s):  
A. F. Sirianni ◽  
I. E. Puddington
Keyword(s):  
Molecular Weight ◽  
Vapor Pressure ◽  
Organic Compounds ◽  
Chemical Stability ◽  
Pressure Difference ◽  
Molecular Weight Range ◽  
Vapor Pressure Difference ◽  
Static Measurement ◽  
Molecular Weights

The molecular weights of organic compounds of known constitution have been determined with satisfactory accuracy, using milligram quantities of materials, by a static measurement of the vapor pressure difference between pure solvents and solutions of the compounds. The method may be used over a considerable temperature range. The suitability of solvents is governed by their chemical stability and vapor pressure. Results obtained using compounds in the molecular weight range of 600–1000 are reported.

scholarly journals Nuclear matrix of HeLa S3 cells. Polypeptide composition during adenovirus infection and in phases of the cell cycle.

1977 ◽  
Vol 72 (1) ◽  
pp. 194-208 ◽  
Author(s):  
L D Hodge ◽  
P Mancini ◽  
F M Davis ◽  
P Heywood
Keyword(s):  
Cell Cycle ◽  
Molecular Weight ◽  
Nuclear Matrix ◽  
Apparent Molecular Weight ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Molecular Weights ◽  
Liver Nuclei ◽  
Hela S3 ◽  
Biochemical Analyses

A subnuclear fraction has been isolated from HeLa S3 nuclei after treatment with high salt buffer, deoxyribonuclease, and dithiothreitol. This fraction retains the approximate size and shape of nuclei and resembles the nuclear matrix recently isolated from rat liver nuclei. Ultrastructural and biochemical analyses indicate that this structure consists of nonmembranous elements as well as some membranous elements. Its chemical composition is 87% protein, 12% phospholipid, 1% DNA, and 0.1% RNA by weight. The protein constituents are resolved in SDS-polyacrylamide slab gels into 30-35 distinguishable bands in the apparent molecular weight range of 14,000 - 200,000 with major peptides at 14,000 - 18,000 and 45,000 - 75,000. Analysis of newly synthesized polypeptides by cylindrical gel electrophoresis reveals another cluster in the 90,000-130,000 molecular weight range. Infection with adenovirus results in an altered polypeptide profile. Additional polypeptides with apparent molecular weights of 21,000, 23,000, and 92,000 become major components by 22 h after infection. Concomitantly, some peptides in the 45,000-75,000 mol wt range become less prominent. In synchronized cells the relative staining capacity of the six bands in the 45,000-75,000 mol wt range changes during the cell cycle. Synthesis of at least some matrix polypeptides occures in all phases of the cell cycle, although there is decreased synthesis in late S/G2. In the absence of protein synthesis after cell division, at least some polypeptides in the 45,000-75,000 mol wt range survive nuclear dispersal and subsequent reformation during mitosis. The possible significance of this subnuclear structure with regard to structure-function relationships within the nucleus during virus replication and during the life cycle of the cell is discussed.

Behavior of Rubber Hydrocarbon in a Molecular Still

1939 ◽  
Vol 12 (4) ◽  
pp. 789-793 ◽  
Author(s):  
W. Harold Smith ◽  
Henry J. Wing
Keyword(s):  
Molecular Weight ◽  
Vapor Pressure ◽  
High Molecular Weight ◽  
Molecular Species ◽  
Decomposition Temperature ◽  
Sedimentation Equilibrium ◽  
Chain Molecules ◽  
Molecular Weights ◽  
Average Value ◽  
Long Chain

Abstract Some investigators believe that rubber consists of associated molecules, and others accept Staudinger's view that long-chain molecules are formed by polymerization. Pummerer, Andriessen and Gündel have obtained a molecular weight as low as 600. Meyer and Mark believe that it is approximately 5,000, although they calculated on the basis of osmotic pressures values as high as 350,000. They, as well as Pummerer, consider that rubber is an associated colloid and that high molecular weights are caused by aggregates, sometimes called micelles. Staudinger, however, considers that the long-chain rubber molecule itself has a molecular weight of 200,000 or even 350,000, and that products with lower values, which may be formed in rubber, result from degradation. if the molecules are small it might be possible to distil them if their vapor pressure could be sufficiently increased, but none would distil without decomposition if the molecules are very large. Because the vapor pressure of rubber below its decomposition temperature is low, it appeared of interest to attempt to distil the material in a molecular still. Paraffin wax and sugar, both substances of relatively high molecular weight, have been successfully distilled in this type of apparatus. Subsequent to the work described in this paper, the molecular weight of sol rubber prepared at this Bureau was determined by Kraemer and Lansing of E. I. du Pont de Nemours & Co., Inc. They used the Svedberg method of sedimentation equilibrium in an ultracentrifuge with ethereal solutions of sol rubber. The temperature of the solutions during determinations was approximately 10° C, and an average value of 460,000 was obtained. There was evidenced of a mixture of molecular species.

scholarly journals Real-time metabolic heat-based specific growth rate soft sensor for monitoring and control of high molecular weight HA production by Streptococcus zooepidemicus.

2020 ◽  
Author(s):  
Naresh Mohan ◽  
Satya Sai Pavan ◽  
Anjali Jayakumar ◽  
Sivakumar Rathinavelu ◽  
Senthilkumar Sivaprakasam
Keyword(s):  
Molecular Weight ◽  
Growth Rate ◽  
Specific Growth Rate ◽  
Real Time ◽  
High Molecular Weight ◽  
Specific Growth ◽  
Fed Batch ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Metabolic Heat

Abstract Background: Hyaluronic acid (HA) is an important mucopolysaccharide of higher molecular weight range and holds sheer economic interest. Its applications are widely acknowledged in rheumatoid arthritis treatment, tissue engineering, and cosmetics industries. This present investigation aims for the fed-batch production of high molecular weight range HA by application of real-time metabolic heat measurements. Results: Fed-batch strategies based on Feedforward (FF) and Feedback (FB) control was devised to improve the Molecular Weight (MW) of HA production by S. zooepidemicus . Metabolic heat measurements (Fermentation calorimetry) were modeled to decipher real-time specific growth rate, [[EQUATION]] was looped to the PID circuit, envisaged to control [[EQUATION]] to their desired setpoint values 0.05 [[EQUATION]] , 0.1 [[EQUATION]] and 0.15 [[EQUATION]] respectively. The developed FB strategy established a robust control on maintaining the specific growth rate (µ) close to the [[EQUATION]] value with a minimal tracking error. Exponential feed rate carried out with a lowest [[EQUATION]] of 0.05 [[EQUATION]] improved the MW of HA significantly to 2.98 MDa and 2.94 MDa for the FF and FB based control strategies respectively. An optimal HA titer of 4.73 g/L was achieved in a FF control strategy at [[EQUATION]] . Biomass and Lactic acid (LA) concentrations were found to be concomitant with the increase in [[EQUATION]] from 0.05 [[EQUATION]] to 0.15 [[EQUATION]] . Superior control of µ at low [[EQUATION]] value was observed to influence positively the HA polymerization attributing to improved MW and desired Polydispersity Index (PDI) of HA. Conclusions: This present investigation attempts to address the metabolic bottleneck in synthesis of high MW HA by S. zooepidemicus and illustrates the application of calorimetric fed-batch control of µ at a narrower range. PID control offers advantage over conventional fed-batch method to synthesize HA at an improved MW. Calorimetric signal based µ control by PID negates adverse effects due to the secretion of other metabolites albeit maintaining homeostasis.

scholarly journals Volatile and Non-Volatile Organic Compounds Stimulate Oviposition by Aphidophagous Predators

Insects ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 683
Author(s):  
Eric W. Riddick
Keyword(s):  
Molecular Weight ◽  
Volatile Organic Compounds ◽  
Vapor Pressure ◽  
Organic Compounds ◽  
Egg Production ◽  
United States Department ◽  
Oviposition Stimulants ◽  
Molecular Weights ◽  
Production Ratio ◽  
Volatile Organic

Introduction: Evidence that volatile organic compounds (VOCs) and non-VOCs stimulate oviposition by aphidophagous predators is scattered throughout the literature. The objectives of this review are to (1) compile records indicating that VOCs and non-VOCs are responsible for oviposition stimulation, (2) calculate an egg production ratio (EPR) for stimulated predators, and (3) determine if EPR is correlated with vapor pressure and molecular weight of active compounds. Methods: The USDA (United States Department of Agriculture), National Agricultural Library, online digital catalog system was used to retrieve abstracts, then the full text of manuscripts on oviposition stimulants for predators. Oviposition-stimulating VOCs and non-VOCS were tabulated with molecular weights and vapor pressure estimates. EPRs were calculated for stimulated coccinellids, syrphids, and chrysopids. Results: Both VOCs and non-VOCs stimulated oviposition behavior by coccinellids and syrphids, but not chrysopids. EPR was greatest for syrphids. Two VOCs, (E)-β-farnesene and 3-methyl-2-butenal, stimulated very high EPR values by the syrphid Episyrphusbalteatus. Regardless of predator taxa, EPR was negatively and positively correlated with molecular weight and vapor pressure, respectively. Conclusions: Syrphids (rather than coccinellids or chrysopids) produce more eggs in response to VOCs. Organic compounds with low-to-moderate molecular weights and moderate-to-high vapor pressures might be most effective oviposition stimulants for aphidophagous predators.

P1099EVALUATION OF THE DEPURATION OF SOLUTES IN THE MIDDLE TO HIGH MOLECULAR WEIGHT RANGE WITH DIFFERENT TECHNIQUES OF HAEMODIALYSIS

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Barbara Cancho Castellano ◽  
Rosa Diaz Campillejo ◽  
Cristina López Arnaldo ◽  
Julián Valladares Alcobendas ◽  
Rosa María Ruiz Calero Cendrero ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Continuous Variables ◽  
Serious Adverse Events ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Statistical Program ◽  
On Line ◽  
Comparative Results ◽  
The One

Abstract Background and Aims Haemodialysis is the most commoly used replacement therapy for chronic kidney disease. We are looking for new solutions to remove solutes in the middle to high molecular weight range. Our objective is to evaluate and compare the purification of small and middle to high molecular weight between 15-45 KDa with Haemodyafiltration On Line postdilutional (HDF-OL-post) technique, Haemodialysis High-Flux (HD-HF) and Haemodialysis Expanded (HDx) using specific high permeability membranes: in the first two techniques polyphenylene membranes (1.7m2) and in the HDx technique cut point membranes PAEs/PVP (1.7 m2). Method 10 chronic prevalent patients on haemodialysis, older than 18 years, without diuresis and stable, 60% males. Mean age 65.3±17.47 years. Time in HD, mean 49.5 months. Etiologies: 20% NAE, 30% ND, 10 % Glomerulopathies, 40% unaffiliated. Vascular Accesses: 50% FAVn, 20% FAVp, 30% CVC-T. They were evaluated for three consecutive weeks with analytics in the intermediate session, modifying the technique and the membrane, keeping the dialysis patient stable. Post-dialysis concentrations of solutes in the middle to high molecular weight range were corrected in relation to haemoconcentration. A comparison of the reduction percentages (RP%) of various molecules was performed. The possible normal distribution was studied in the continuous variables with the Shapiro-Wilk test and the comparison of means using the t-Student or Wilconson test as the most appropriate. SPSS statistical program 17.0. Results No serious adverse events or allergies were recorded. The comparative results between the three techniques are shown in the figure 1. Conclusion The mean reduction of medium molecules (β2-microglobulin, cystatin-C) was not lower in HDx compared to HDF-OL-post. From 20 KDa there is no greater capacity to reduce solutes in HDx in our sample than in the other techniques. Between the three techniques, the HDF-Ol-post is the one that shows a higher percentage of mean reduction of α1-acid glycoprotein and albumin.

scholarly journals The solubility of fibrinogen in solutions containing dextrans of various molecular weights (Short Communication)

1974 ◽  
Vol 143 (3) ◽  
pp. 767-769 ◽  
Author(s):  
Michael W. Rampling
Keyword(s):  
Molecular Weight ◽  
Short Communication ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Molecular Weights ◽  
Steric Exclusion

The effect of dextrans of various molecular weights on the solubility of fibrinogen was investigated. The results indicate that the prime effect responsible for the observed changes of solubility was steric exclusion. This applies over the whole molecular-weight range of dextrans used, i.e. from 5700 to 76000.

scholarly journals Real-time metabolic heat-based specific growth rate soft sensor for monitoring and control of high molecular weight HA production by Streptococcus zooepidemicus.

2020 ◽  
Author(s):  
Naresh Mohan ◽  
Satya Sai Pavan ◽  
Anjali Jayakumar ◽  
Sivakumar Rathinavelu ◽  
Senthilkumar Sivaprakasam
Keyword(s):  
Molecular Weight ◽  
Growth Rate ◽  
Specific Growth Rate ◽  
Real Time ◽  
High Molecular Weight ◽  
Specific Growth ◽  
Fed Batch ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Metabolic Heat

Abstract Background: Hyaluronic acid (HA) is an important mucopolysaccharide of higher molecular weight range and holds sheer economic interest. Its applications are widely acknowledged in rheumatoid arthritis treatment, tissue engineering, and cosmetics industries. This present investigation aims for the fed-batch production of high molecular weight range HA by application of real-time metabolic heat measurements.Results: Fed-batch strategies based on Feedforward (FF) and Feedback (FB) control was devised to improve the Molecular Weight (MW) of HA production by S. zooepidemicus. Metabolic heat measurements (Fermentation calorimetry) were modeled to decipher real-time specific growth rate, µest was looped to the PID circuit, envisaged to control µSP to their desired setpoint values 0.05 h-1, 0.1 h-1 and 0.15 h-1 respectively. The developed FB strategy established a robust control on maintaining the specific growth rate (µ) close to the µSP value with a minimal tracking error. Exponential feed rate carried out with a lowest µSP of 0.05 h-1 improved the MW of HA significantly to 2.98 MDa and 2.94 MDa for the FF and FB based control strategies respectively. An optimal HA titer of 4.73 g/L was achieved in a FF control strategy at µSP = 0.15 h-1. Biomass and Lactic acid (LA) concentrations were found to be concomitant with the increase in µSP from 0.05 h-1 to 0.15 h-1. Superior control of µ at low µSP value was observed to influence positively the HA polymerization attributing to improved MW and desired Polydispersity Index (PDI) of HA.Conclusions: This present investigation attempts to address the metabolic bottleneck in synthesis of high MW HA by S. zooepidemicus and illustrates the application of calorimetric fed-batch control of µ at a narrower range. PID control offers advantage over conventional fed-batch method to synthesize HA at an improved MW. Calorimetric signal based µ control by PID negates adverse effects due to the secretion of other metabolites albeit maintaining homeostasis.

Structure and Solution Properties of High Molecular Weight Butadiene-Styrene Copolymers

1957 ◽  
Vol 30 (1) ◽  
pp. 315-325
Author(s):  
R. B. MacFarlane ◽  
L. A. McLeod
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Complex Structure ◽  
Mixed Solvents ◽  
Solution Time ◽  
Solution Viscosity ◽  
Solution Properties ◽  
Molecular Weight Range ◽  
Viscosity Measurements ◽  
Commercial Practice

Abstract Production of high molecular weight copolymers of butadiene and styrene for use in oil-extended rubbers has aroused interest in the solution properties of copolymers above the molecular weight range commonly encountered in commercial practice. It has been observed that solubility of such polymers in toluene is a time-dependent phenomenon and the apparent solubility can increase continuously, in the absence of agitation, for as long as 800 hours. Although a standard Harris cage solubility test may show the presence of 50% gel, other properties do not confirm the presence of any appreciable quantities of insoluble material. Mild agitation rapidly promotes almost complete solubility. Dilute solution viscosity measurements are very misleading unless the influence of solution time is recognized and apparent intrinsic viscosities rise progressively with time of contact of the sample with solvent. This time-dependence of solution has been found to occur at conversions higher than 50% and is also a function of the amount of modifier used in the polymerization recipe. It has not been possible to shorten the solution time for viscosity measurements by mild heating or gentle agitation. Mixed solvents cause a change in the amount of increase of the apparent intrinsic viscosity but do not shorten the time to equilibrium. Measurement of the slope constant in the Huggins viscosity equation indicate that these solubility and viscosity effects coincide with the appearance of a marked degree of branching in the polymer molecules. The effect is, therefore, interpreted as being caused by the relatively slow disentanglement of molecules of complex structure.

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