The Action of Copper Salts on Raw Rubber

1934 ◽  
Vol 7 (4) ◽  
pp. 618-631 ◽  
Author(s):  
B. V. Buizov ◽  
V. S. Molodenskii ◽  
N. I. Mikhailov
Keyword(s):  
Atmospheric Oxygen ◽  
Good Reason ◽  
Copper Salt ◽  
Copper Salts ◽  
Destructive Effect ◽  
Initial Stage ◽  
Destructive Action ◽  
Long Time ◽  
Effect Of Copper ◽  
Short Time

Abstract 1. An examination of the literature makes open to doubt the view of many investigators that copper salts exert a destructive action on rubber by functioning as catalysts which start the autoöxidation of rubber and then promote this autooxidation. The literature available indicates with just as good reason that there is another explanation of the effect of copper salts, viz., that the destructive action of these salts is characterized in its initial stage by a disaggregation of the. rubber. As a result of this disaggregation there is an increased surface of rubber micelles with an accumulation of double bonds. The rubber is then more readily susceptible to oxidation by atmospheric oxygen. 2. The detailed study in the present work of the action of copper salts on rubber solutions has shown that the complicated process as a whole can be divided into separate partial processes, i. e., into a desolvation, a micellar disaggregation, and a molecular disaggregation. 3. Observations of changes in weight and of the properties of rubber films proved conclusively that copper salts first bring about a desolvation of the rubber micelles and then a disaggregation. The latter proceeds without any accompanying oxidation of the rubber. Following this there is an oxidation of the irreversibly degenerated rubber. 4. The influence of oxygen on the appearance of stickiness is very slight, in fact tackiness appears both in the presence and the absence of oxygen. 5. The stickiness of rubber samples to which a copper salt has been added is always to be found in the interior of the samples, while a brittleness appears on the surfaces. 6. These facts lead to the conclusion that the stickiness of raw rubber appears as a result of disaggregation, whereas brittleness is the result of oxidation. 7. The destructive effect of copper salts depends to a large extent upon the state of dispersion of the copper salt in the rubber; the more finely dispersed is the salt in the rubber, the greater is its effect. 8. Copper salts accelerate vulcanization, without however increasing the proportion of combined sulfur. Upon standing a long time, rubber containing a copper salt loses completely its power of vulcanization. This latter phenomenon can be explained by the fact that copper compounds bring about in a relatively short time the disaggregation which is necessary to vulcanization, whereas after a longer time they destroy the rubber completely.

Isoprene and Rubber. Part 47. The Decomposition of Rubber by Acids

1937 ◽  
Vol 10 (3) ◽  
pp. 445-450
Author(s):  
H. P. Mojen
Keyword(s):  
Atmospheric Carbon Dioxide ◽  
Atmospheric Oxygen ◽  
Free Play ◽  
Destructive Effect ◽  
Organic Bases ◽  
Inorganic Acids ◽  
Close Relationship ◽  
Rubber Part ◽  
Long Time ◽  
Effect Of Oxygen

Abstract The phenomena observed in the experiments which have been described can be explained in the following way. As already mentioned, raw rubber contains certain antioxygens which protect the rubber molecules from attack by oxygen. Very little is known about the nature of these antioxygens, but it is probably correct to assume that these substances are of a basic nature, like commercial antioxygens, which for the most part are complex organic bases. The activity of these anti-catalysts is stopped by the addition of organic or inorganic acids. As a result there is no longer any obstacle to an attack by oxygen, and decomposition can proceed under these conditions much more rapidly and much more extensively. The antioxygens are destroyed by the acids, even when oxygen is excluded during the experiments, but demolition of the fiber molecules does not then take place. The intense destructive effect of oxygen on rubber does not therefore depend on the action of acids on the fiber molecules of rubber, but is to be attributed solely to the fact that antioxygens which inhibit decomposition by oxygen are destroyed; destruction of the rubber itself is caused only by oxygen. It is not impossible that these phenomena bear a close relationship to the stickiness acquired by rubber. Rubber which has become sticky is composed of extensively decomposed rubber molecules. This phenomenon is noticeable at times in rubber goods which have been stored for a long time, and may be explained by the fact that atmospheric carbon dioxide destroys the natural antioxygens in the rubber. With their destruction, atmospheric oxygen then has free play to attack the rubber molecules. The acidic substances which are formed in this oxidation then destroy any remaining antioxygens, so that oxygen can destroy all of the rubber. Grateful acknowledgment is due Professor Staudinger, at whose instigation this work was carried out, who offered advice in various ways, and who took an active part in the investigation.

Droit Administratif

1929 ◽  
Vol 3 (3) ◽  
pp. 355-364
Author(s):  
Achille Mestre
Keyword(s):  
Great Britain ◽  
Common Law ◽  
Good Reason ◽  
Administrative Law ◽  
Considerable Time ◽  
Judicial Practice ◽  
Long Time ◽  
The Common ◽  
English Law ◽  
Short Time

A French jurist who seeks to explain to the English public the principles governing administrative law as they are understood in France, is beset at the same moment by conflicting feelings of uneasiness and confidence. He recollects at the outset that, according to a classical doctrine which has been true for a considerable time and which is expressed in Dicey's works in the most brilliant formula, England does not possess to any extent in its legal organization a system of ideas which could have any claim to be compared to the French droit administratif or indeed could be regarded as parallel to it with any exactness. Is it not therefore presumptuous for a Frenchman to attempt to explain to English lawyers the leading characteristics of an institution which might certainly appear to them unusual, if not grotesque? And yet when a traveller has stayed a short time in Great Britain, has talked with the recognized authorities of that country, has asked questions, has made notes, has dipped into the recent works on English law, has glanced with an unprejudiced eye at the whole trend of legal institutions at the present day, he cannot help being struck by a certain lack of harmony between the official doctrine, which for such a long time has had good reason to say that there is no administrative law in England, and the judicial practice which, owing to the creation of new jurisdictions, to the introduction of new forms of procedure, and to the needs originating in ihe obvious inadequacy of inherited views, seems to pave the way for the introduction into England of a droit administratif and the recognition of principles derogatory to the common law—principles which are adapted to playing in English law the part which droit administratif played in the French common law chiring the nineteenth century, and still plays.

Short-Time Tests for Long-Time Endurance

1923 ◽  
Vol 128 (4) ◽  
pp. 264-264
Author(s):  
J. W. Harsch
Keyword(s):  
Long Time ◽  
Short Time

Effect of Vial shaking on Loading Time of Epirubicin into Drug-Eluting Bead

2015 ◽  
Vol 5 (3) ◽  
Author(s):  
Kenji Ikeda ◽  
Yusuke Kawamura ◽  
Masahiro Kobayashi ◽  
Taito Fukushima ◽  
Yushi Sorin ◽  
...  
Keyword(s):  
Antitumor Agent ◽  
Loading Rates ◽  
Vortex Mixer ◽  
Long Time ◽  
Group A ◽  
Drug Eluting ◽  
Large Hepatocellular Carcinoma ◽  
Group B ◽  
Time Required ◽  
Short Time

Background: Although DC Bead has been useful in treatment of multiple and large hepatocellular carcinoma, loading time of doxorubicin into the DC Bead takes a long time of 30-120 minutes. Epirubicin is also used as an antitumor agent together with DC Bead, but its loading efficiency was not sufficiently elucidated. Methods: To shorten loading time of epirubicin into DC Bead (100-300µm, 300-500µm, 500-700µm), we examined the following three methods after mixing the drug: (a) let stand in room temperature, (b) agitated for 30 seconds with Vortex mixer, and (c) sonicated for 30 seconds with ultrasonic cleaner. After loading of epirubicin by each method, supernatant concentration for epirubicin was assayed at 5, 10, 30, 60, and 120 minutes. Results: Epirubicin loading rates for small bead (100-300µm) at 5 minutes were 82.9 % in group a, 93.8% in group b, and 79.9 % in group c. Similarly, medium bead (300-500µm), 40.1% in group a, 65.7% in group b and 45.5% in group c, respectively. In large-sized bead (500-700µm), loaded rates of epirubicin were 38.8% in group a, 59.0% in group b and 48.0% in group c. Agitation of mixture of epirubicin and DC Bead with Vortex mixer significantly shortened the loading time, but sonication did not affect the time required. Microscopic examination did not lead to any morphological change of microspheres in all the methods. Conclusions: Short time of agitation with Vortex mixer reduced the necessary time for loading of epirubicin in every standard of DC Bead.

Robust Test Method of TSOP PEMs for Space Application

2019 ◽  
Author(s):  
Yasunobu Iwai ◽  
Koichi Shinozaki ◽  
Daiki Tanaka
Keyword(s):  
Evaluation Method ◽  
Low Cost ◽  
Reliability Evaluation ◽  
Test Method ◽  
Thermal Shock Test ◽  
Space Application ◽  
Space Applications ◽  
Limit Test ◽  
Long Time ◽  
Short Time

Abstract Compared with space parts, consumer parts are highly functional, low cost, compact and lightweight. Therefore, their increased usage in space applications is expected. Prior testing and evaluation on space applicability are necessary because consumer parts do not have quality guarantees for space application [1]. However, in the conventional reliability evaluation method, the test takes a long time, and the problem is that the robustness of the target sample can’t be evaluated in a short time. In this report, we apply to the latest TSOP PEM (Thin Small Outline Package Plastic Encapsulated Microcircuit) an evaluation method that combines preconditioning and HALT (Highly Accelerated Limit Test), which is a test method that causes failures in a short time under very severe environmental conditions. We show that this method can evaluate the robustness of TSOP PEMs including solder connections in a short time. In addition, the validity of this evaluation method for TSOP PEM is shown by comparing with the evaluation results of thermal shock test and life test, which are conventional reliability evaluation methods.

The Spread of Pollutants from Harbour Sludge Depots

1984 ◽  
Vol 16 (3-4) ◽  
pp. 623-633
Author(s):  
M Loxham ◽  
F Weststrate
Keyword(s):  
Time Scales ◽  
Molecular Diffusion ◽  
Near Field ◽  
Parameter Analysis ◽  
Migration Patterns ◽  
Long Time ◽  
Dilution Effects ◽  
Short Time ◽  
Harbour Sludge

It is generally agreed that both the landfill option, or the civil techniques option for the final disposal of contaminated harbour sludge involves the isolation of the sludge from the environment. For short time scales, engineered barriers such as a bentonite screen, plastic sheets, pumping strategies etc. can be used. However for long time scales the effectiveness of such measures cannot be counted upon. It is thus necessary to be able to predict the long term environmenttal spread of contaminants from a mature landfill. A model is presented that considers diffusion and adsorption in the landfill site and convection and adsorption in the underlaying aquifer. From a parameter analysis starting form practical values it is shown that the adsorption behaviour and the molecular diffusion coefficient of the sludge, are the key parameters involved in the near field. The dilution effects of the far field migration patterns are also illustrated.

Alteration of intrapancreatic serotonin, homocysteine, TNF-α, and NGF levels as predisposing factors for diabetes following exposure to 900-MHz waves

2021 ◽  
pp. 074823372110226
Author(s):  
Gholamali Jelodar ◽  
Mansour Azimzadeh ◽  
Fatemeh Radmard ◽  
Narges Darvishhoo
Keyword(s):  
Cell Damage ◽  
Pancreatic Beta Cell ◽  
Predisposing Factors ◽  
Male Rats ◽  
Control Group ◽  
Predisposing Factor ◽  
Time Exposure ◽  
Tnf Α ◽  
Long Time ◽  
Short Time

Exposure to mobile phone radiation causes deleterious health effects on biological systems. The objects of this study were to investigate the effect of 900-MHz radiofrequency waves (RFW) emitted from base transceiver station antenna on intrapancreatic homocysteine (Hcy), tumor necrosis factor-α (TNF-α), and nerve growth factor (NGF) as predisposing factors involved in pancreatic beta cell damage. Thirty male rats (Sprague-Dawley, 200 ± 10 g) were randomly divided into the control (without any exposure) and exposed groups: short time (2 h/day), long time (4 h/day), and exposed to 900-MHz RFW for 30 consecutive days. On the last days of the experiment, animals were killed and pancreas tissue was dissected out for evaluation of serotonin, Hcy, TNF-α, and NGF. There was a significant decrease in the serotonin and NGF levels in the pancreatic tissue of exposed groups compared to the control group ( p < 0.05). Also, the levels of serotonin and NGF in the long-time exposure were significantly lower than the short-time exposure ( p < 0.05). However, levels of Hcy and TNF-α were significantly increased in the pancreas of exposed groups compared to the control groups ( p < 0.05). Exposure to 900-MHz RFW decreased pancreatic NGF and serotonin levels and increased the proinflammatory markers (Hcy and TNF-α), which can be a predisposing factor for type 2 diabetes.

scholarly journals Internal dosimetry in F-18 FDG PET examinations based on long-time-measured organ activities using total-body PET/CT: does it make any difference from a short-time measurement?

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Pengcheng Hu ◽  
Xin Lin ◽  
Weihai Zhuo ◽  
Hui Tan ◽  
Tianwu Xie ◽  
...  
Keyword(s):  
Effective Dose ◽  
Dynamic Model ◽  
Bladder Wall ◽  
Time Measurement ◽  
Post Injection ◽  
Time Activity ◽  
Pet Ct ◽  
Long Time ◽  
Total Body ◽  
Short Time

Abstract Purpose A 2-m axial field-of-view, total-body PET/CT scanner (uEXPLORER) has been recently developed to provide total-body coverage and ultra-high sensitivity, which together, enables opportunities for in vivo time-activity curve (TAC) measurement of all investigated organs simultaneously with high temporal resolution. This study aims at quantifying the cumulated activity and patient dose of 2-[F-18]fluoro-2-deoxy-D-glucose (F-18 FDG ) imaging by using delayed time-activity curves (TACs), measured out to 8-h post-injection, for different organs so that the comparison between quantifying approaches using short-time method (up to 75 min post-injection) or long-time method (up to 8 h post-injection) could be performed. Methods Organ TACs of 10 healthy volunteers were collected using total-body PET/CT in 4 periods after the intravenous injection of F-18 FDG. The 8-h post-injection TACs of 6 source organs were fitted using a spline method (based on Origin (version 8.1)). To compare with cumulated activity estimated from spline-fitted curves, the cumulated activity estimated from multi-exponential curve was also calculated. Exponential curve was fitted with shorter series of data consistent with clinical procedure and previous dosimetry works. An 8-h dynamic bladder wall dose model considering 2 voiding were employed to illustrate the differences in bladder wall dose caused by the different measurement durations. Organ absorbed doses were further estimated using Medical Internal Radiation Dose (MIRD) method and voxel phantoms. Results A short-time measurement could lead to significant bias in estimated cumulated activity for liver compared with long-time-measured spline fitted method, and the differences of cumulated activity were 18.38% on average. For the myocardium, the estimated cumulated activity difference was not statistically significant due to large variation in metabolism among individuals. The average residence time differences of brain, heart, kidney, liver, and lungs were 8.38%, 15.13%, 25.02%, 23.94%, and 16.50% between short-time and long-time methods. Regarding effective dose, the maximum differences of residence time between long-time-measured spline fitted curve and short-time-measured multi-exponential fitted curve was 9.93%. When using spline method, the bladder revealed the most difference in the effective dose among all the investigated organs with a bias up to 21.18%. The bladder wall dose calculated using a long-time dynamic model was 13.79% larger than the two-voiding dynamic model, and at least 50.17% lower than previous studies based on fixed bladder content volume. Conclusions Long-time measurement of multi-organ TACs with high temporal resolution enabled by a total-body PET/CT demonstrated that the clinical procedure with 20 min PET scan at 1 h after injection could be used for retrospective dosimetry analysis in most organs. As the bladder content contributed the most to the effective dose, a long-time dynamic model was recommended for the bladder wall dose estimation.

scholarly journals Inhibition of CCL7 derived from Mo-MDSCs prevents metastatic progression from latency in colorectal cancer

2021 ◽  
Vol 12 (5) ◽  
Author(s):  
Xiaoli Ren ◽  
Jianbiao Xiao ◽  
Wanning Zhang ◽  
Feifei Wang ◽  
Yongrong Yan ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Suppressor Cells ◽  
Metastatic Progression ◽  
Ht29 Cells ◽  
Metastatic Cells ◽  
Long Time ◽  
Mice Liver ◽  
Short Time ◽  
Related Proteins

AbstractIn colorectal cancer (CRC), overt metastases often appear after years of latency. But the signals that cause micro-metastatic cells to remain indolent, thereby enabling them to survive for extended periods of time, are unclear. Immunofluorescence and co-immunoprecipitation assays were used to explore the co-localization of CCL7 and CCR2. Immunohistochemical (IHC) assays were employed to detect the characters of metastatic HT29 cells in mice liver. Flow cytometry assays were performed to detect the immune cells. Bruberin vivo MS FX Pro Imager was used to observe the liver metastasis of CRC in mice. Quantitative real-time PCR (qRT-PCR) and western blot were employed to detect the expressions of related proteins. Trace RNA sequencing was employed to identify differentially expressed genes in MDSCs from liver micro-M and macro-M of CRC in mice. Here, we firstly constructed the vitro dormant cell models and metastatic dormant animal models of colorectal cancer. Then we found that myeloid-derived suppressor cells (MDSCs) were increased significantly from liver micro-metastases to macro-metastases of CRC in mice. Moreover, monocytic MDSCs (Mo-MDSC) significantly promoted the dormant activation of micro-metastatic cells compared to polymorphonuclear MDSCs (PMN-MDSC). Mechanistically, CCL7 secreted by Mo-MDSCs bound with membrane protein CCR2 of micro-metastatic cells and then stimulated the JAK/STAT3 pathway to activate the dormant cells. Low-dose administration of CCL7 and MDSCs inhibitors in vivo could significantly maintain the CRC metastatic cells dormant status for a long time to reduce metastasis or recurrence after radical operation. Clinically, the level of CCL7 in blood was positively related to the number of Mo-MDSCs in CCR patients, and highly linked with the short-time recurrence and distant metastasis. CCL7 secreted by Mo-MDSCs plays an important role in initiating the outgrowth of metastatic latent CRC cells. Inhibition of CCL7 might provide a potential therapeutic strategy for the prevention of metastasis recurrence.

scholarly journals Expression Level of Mature miR172 in Wild Type and StSUT4-Silenced Plants of Solanum tuberosum Is Sucrose-Dependent

2021 ◽  
Vol 22 (3) ◽  
pp. 1455
Author(s):  
Varsha Garg ◽  
Aleksandra Hackel ◽  
Christina Kühn
Keyword(s):  
Solanum Tuberosum ◽  
Wild Type ◽  
Potato Plants ◽  
Mature Leaves ◽  
In Vitro Plantlets ◽  
Long Time ◽  
Short Time ◽  
Cut Leaves

In potato plants, the phloem-mobile miR172 is involved in the sugar-dependent transmission of flower and tuber inducing signal transduction pathways and a clear link between solute transport and the induction of flowering and tuberization was demonstrated. The sucrose transporter StSUT4 seems to play an important role in the photoperiod-dependent triggering of both developmental processes, flowering and tuberization, and the phenotype of StSUT4-inhibited potato plants is reminiscent to miR172 overexpressing plants. The first aim of this study was the determination of the level of miR172 in sink and source leaves of StSUT4-silenced as well as StSUT4-overexpressing plants in comparison to Solanum tuberosum ssp. Andigena wild type plants. The second aim was to investigate the effect of sugars on the level of miRNA172 in whole cut leaves, as well as in whole in vitro plantlets that were supplemented with exogenous sugars. Experiments clearly show a sucrose-dependent induction of the level of mature miR172 in short time as well as long time experiments. A sucrose-dependent accumulation of miR172 was also measured in mature leaves of StSUT4-silenced plants where sucrose export is delayed and sucrose accumulates at the end of the light period.

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