scholarly journals Supercritical Assisted Electrospray: An Improved Micronization Process

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 244 ◽  
Author(s):  
Lucia Baldino ◽  
Stefano Cardea ◽  
Ernesto Reverchon
Keyword(s):  
Molecular Weight ◽  
Surface Tension ◽  
Supercritical Co2 ◽  
Liquid Mixture ◽  
Particle Generation ◽  
New Process ◽  
Consequent Reduction ◽  
Nanometric Particles ◽  
Traditional Process ◽  
Very High

A new process is proposed that can largely improve classical electrospray (ESPR) atomization, thanks to the addition of supercritical CO2 (SC-CO2) to the liquid mixture, in which a polymer is dissolved, forming an expanded liquid. The consequent reduction of surface tension and viscosity allows the production of micrometric or nanometric particles of controlled size and distribution at a production rate up to one hundred times that of the traditional process. The new process was applied to particle generation from a very high molecular weight polyvinylpyrrolidone (PVP) and tested at different polymer percentages by weight and at different pressures. Repeatable microparticle diameters and distributions were obtained, ranging between 0.55 and 2.25 µm at PVP concentrations from 1 to 5% w/w and pressures between 80 and 120 bar.

Coactivation of Delayed-Action Vulcanization. Part I. Polymeric, Nonmigratory Cure Coactivators for Accelerated Sulfur Vulcanization

1989 ◽  
Vol 62 (5) ◽  
pp. 957-972
Author(s):  
A. Y. Coran ◽  
F. Ignatz-Hoover ◽  
L. H. Davis
Keyword(s):  
Molecular Weight ◽  
Minimum Loss ◽  
Synthetic Rubber ◽  
Curing Characteristics ◽  
Sulfur Vulcanization ◽  
Delayed Action ◽  
Very High ◽  
Rubber Article

Abstract Rubbery vinylpyridine-butadiene copolymers, containing 20–65% by weight of vinylpyridine monomer units, are effective coactivators of vulcanization for TBBS-accelerated sulfur-vulcanized SBR. In addition to emulsion SBR, the new co-activator has been evaluated in copositions of solution SBR, BR, NR, and various blends. The co-activator is active in all of the compositions which contain butadiene-derived synthetic rubber. This includes blends such as SBR/BR, solution-SBR/BR, SBR/NR, BR/NR, SBR/BR/NR, etc. There is little or no activity in which NR is the only polymer. The most efficacious copolymers contain between 30 and 60% 2-vinylpyridine. The incorporation of such a copolymer into an unvulcanized butadiene-derived rubber mix can give a substantial increase in the rate of crosslink formation with only a minimum loss of scorch resistance. Since the polymeric coactivators are very high in molecular weight, it can be at least tentatively concluded that they will not migrate from one component stock to another in a built-up multi-stock rubber article, either before or during vulcanization. Since the curing characteristics of a vinylpyridine-copolymer-containing TBBS-accelerated stock can be similar to those of TBBS-accelerated NR, it might be concluded that the new additives will solve some of the problems in balancing the cures of adjacent NR and SBR stocks in a multicomponent cured rubber article.

Erratum to ‘Effect of soft segment molecular weight on the microcellular foaming behavior of TPU using supercritical CO2’ [J. Supercrit. Fluids, 160, 2020, 104816]

2021 ◽  
Vol 171 ◽  
pp. 105154
Author(s):  
Mohammadreza Nofar ◽  
Bige Batı ◽  
Emine Büşra Küçük ◽  
Amirjalal Jalali
Keyword(s):  
Molecular Weight ◽  
Supercritical Co2 ◽  
Soft Segment ◽  
Microcellular Foaming ◽  
Foaming Behavior

scholarly journals Inducible overexpression and secretion of int-1 protein.

1989 ◽  
Vol 9 (8) ◽  
pp. 3377-3384 ◽  
Author(s):  
J Papkoff
Keyword(s):  
Molecular Weight ◽  
Cho Cells ◽  
Secretory Pathway ◽  
Mammary Tissue ◽  
Neural Tubes ◽  
Molecular Weights ◽  
Activation Of Transcription ◽  
Mouse Mammary Tumor ◽  
Tumor Virus ◽  
Very High

The int-1 proto-oncogene is a target for insertional activation of transcription by mouse mammary tumor virus in many murine mammary tumors. Whereas no expression of int-1 is seen in normal mammary tissue, int-1 RNA can be detected in normal mice in the neural tubes of midgestation embryos and in postmeiotic spermatocytes from adult testes. I report here the results of a study in which several different antibodies against synthetic peptides were produced and used to characterize the processing and secretion of int-1 protein. CHO cells were transfected with an inducible int-1 expression vector that was subsequently amplified to generate cell lines expressing very high levels of int-1 protein. Immunoprecipitation of [35S]cysteine-labeled cell lysates from these CHO cells yielded large amounts of four immature forms of int-1 glycoprotein (molecular weights of 36,000, 38,000, 40,000, and 42,000). A significant fraction of these int-1 species formed disulfide-linked multimers. Pulse-chase and glycosidase digestion studies demonstrated that some of the immature species of int-1 protein move through the secretory pathway and are processed to a mature heterogeneous glycoprotein with a molecular weight of about 44,000. Suramin treatment of the CHO cells during pulse-chase experiments increased the amount of 44,000-molecular-weight int-1 protein in the culture medium.

Vaporization and Ultra-Fine Particle Generation during the Plasma Spraying Process

1997 ◽  
Author(s):  
K.A. Gross ◽  
P. Fauchais ◽  
M. Vardelle ◽  
J. Tikkanen ◽  
J. Keskinen
Keyword(s):  
Fine Particles ◽  
High Concentration ◽  
Thermal Spray Process ◽  
Particle Generation ◽  
Spray Process ◽  
Ultra Fine Particle ◽  
Fast Cooling ◽  
Ultra Fine Particles ◽  
Plasma Spraying Process ◽  
Very High

Abstract The thermal spray process melts powder at very high temperatures and propels the molten material to the substrate to produce a coherent deposit. This heating produces a certain amount of vaporization of the feedstock. Upon exiting the plasma plume the fast cooling conditions lead to condensation of the vapor. An electrical low pressure impactor was used to monitor the concentration of ultra-fine particles at various radial and axial distances. Metal, namely iron powder, showed very high concentration levels which increase with distance. Ultra-fine particles from ZrO2-8Y2O3 reached a peak concentration at 6 cm. Use of an air barrier during spraying decreases the population of ultra-fine particles facilitating the production of a stronger coating.

scholarly journals Average molecular weight of surfactants in aerosols

2007 ◽  
Vol 7 (5) ◽  
pp. 13805-13838 ◽  
Author(s):  
M. T. Latif ◽  
P. Brimblecombe
Keyword(s):  
Molecular Weight ◽  
Surface Tension ◽  
Atmospheric Aerosols ◽  
Average Molecular Weight ◽  
Molecular Size ◽  
Weight Fraction ◽  
Ozone Exposure ◽  
Before And After ◽  
Fine Mode ◽  
Active Substances

Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can be correlated with surface tension as determined by pendant drop analysis. The effect of surface tension was more clearly indicated in fine mode aerosol extracts. The concentration of MBAS and EVAS was determined before and after ultrafiltration analysis using AMICON centrifuge tubes that define a 5000 Da (5 K Da) nominal molecular weight fraction. Overall, MBAS and to a greater extent EVAS predominates in fraction with molecular weight below 5 K Da. In case of aerosols collected in Malaysia the higher molecular fractions tended to be a more predominant. The MBAS and EVAS are correlated with yellow to brown colours in aerosol extracts. Further experiments showed possible sources of surfactants (e.g. petrol soot, diesel soot) in atmospheric aerosols to yield material having molecular size below 5 K Da except for humic acid. The concentration of surfactants from these sources increased after ozone exposure and for humic acids it also general included smaller molecular weight surfactants.

scholarly journals Screening for CLCN5 mutation in renal calcium stone formers patients

2005 ◽  
Vol 77 (1) ◽  
pp. 95-101 ◽  
Author(s):  
Maria Alice P. Rebelo ◽  
Vera Tostes ◽  
Nordeval C. Araújo ◽  
Sabrina V. Martini ◽  
Bruno F. Botelho ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Stone Disease ◽  
Idiopathic Hypercalciuria ◽  
Low Molecular Weight ◽  
Normal Range ◽  
Clcn5 Gene ◽  
Channel Gene ◽  
Stone Formers ◽  
Very High ◽  
Mild Renal Insufficiency

Thirty-five patients (23 males and 12 females), age 35 ± 13 years old, presenting either idiopathic calcium nephrolithiasis, nephrocalcinosis or mild renal failure with idiopathic calcium nephrolithiasis were selected for the analysis of low molecular weight proteinuria and the possible mutations occurrence in the chloride channel gene CLCN5. The urinary ratio of beta2-microglobulin and creatinine (beta2M/Cr) was very high in a transplanted woman with nephrocalcinosis (>3.23 mg/mmol) and slightly high in five patients (>0.052 or < 1.0 mg/mmol) with multiple urological manipulations. Other studied patients showed beta2M/Cr ratio at normal range (0.003-0.052 mg/mmol) without gender difference (p > 0.05). Mutation analysis of CLCN5 gene was performed in 26 patients of 35 selected (11 with idiopathic hypercalciuria; 6 men with normal calciuria; 3 with mild renal insufficiency and 6 with nephrocalcinosis) and was normal in all subjects even in those with abnormal molecular weight proteinuria. Conclusion: CLCN5 gene mutation is not a common cause of kidney stone disease or nephrocalcinosis in a group of Brazilian patients studied.

Inorganic Substances with Rubber-like Properties

1936 ◽  
Vol 9 (3) ◽  
pp. 422-425
Author(s):  
Kurt H. Meyer
Keyword(s):  
Molecular Weight ◽  
Common Knowledge ◽  
Elementary Cell ◽  
Double Refraction ◽  
Special Position ◽  
Inorganic Substances ◽  
The Subject ◽  
Elastic Form ◽  
Very High ◽  
Long Chains

Abstract Two inorganic substances with elasticity similar to that of rubber are described in the literature of the subject, viz., elastic sulfur and polyphosphonitrilic chloride. In this paper we shall deal with investigations of both. It is common knowledge that sulfur heated to 170° becomes highly viscous; if then cooled, e. g., by plunging into water, it yields an amorphous elastic product. If threads of this amorphous product are stretched, they show a double refraction, and, as Trilat has found, develop a fiber-diagram. With Go the author has examined this diagram, and deduced from it the following arrangement of the sulfur atoms: long chains of sulfur atoms, linked by strong homeopolar valences, are arranged parallel to the direction of stretching. Their special position in the elementary cell is shown in Fig. 1. In a recent publication, Warren has made it clear that ordinary sulfur is made up of 8-atom rings. The molecular weight of the elastic form Sn is not known, but seems to be very high. We know from earlier work that the melting of sulfur produces an equilibrium between the two forms, and this shifts, at higher temperatures, in favor of the chain-sulfur. About 1000 calories per gram atom S are consumed in the transformation of S8 into Sn.

scholarly journals The multiple complexes formed by the interaction of platelet factor 4 with heparin

1980 ◽  
Vol 191 (3) ◽  
pp. 769-776 ◽  
Author(s):  
P E Bock ◽  
M Luscombe ◽  
S E Marshall ◽  
D S Pepper ◽  
J J Holbrook
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Chain Length ◽  
Salt Concentration ◽  
Human Platelet ◽  
Platelet Factor 4 ◽  
High Protein ◽  
Platelet Factor ◽  
The Stability ◽  
Very High

The anisotropy of the fluorescence of dansyl (5-dimethylaminonaphthalene-1- sulphonyl) groups covalently attached to human platelet factor 4 was used to detect the macromolecular compounds formed when the factor was mixed with heparin. At low heparin/protein ratios a very-high-molecular-weight compound (1) was formed that dissociated to give a smaller compound (2) when excess heparin was added. 2. A large complex was also detected as a precipitate that formed at high protein concentrations in chloride buffer. It contained 15.7% (w/w) polysaccharide, equivalent to four or five heparin tetrasaccharide units per protein tetramer. In this complex, more than one molecule of protein binds to each heparin molecule of molecular weight greater than about 6 × 10(3).3. The stability of these complexes varied with pH, salt concentration and the chain length of the heparin. The limit complexes found in excess of the larger heparins consisted of only one heparin molecule per protein tetramer, and the failure to observe complexes with four heparin molecules/protein tetramer is discussed.

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