Effect of Vulcanization on Rubber Structure. A Problem in Probabilities

1940 ◽  
Vol 13 (2) ◽  
pp. 196-208
Author(s):  
Warren F. Busse
Keyword(s):  
Chemical Analysis ◽  
Physical Properties ◽  
Organic Molecules ◽  
Cold Winter ◽  
Winter Weather ◽  
The Past ◽  
Points Of View ◽  
Physical And Chemical ◽  
Present View

Abstract In Goodyear's day, the problem of understanding the process of vulcanization could be expressed by the question: “Why does heating rubber with sulfur keep it from getting soft and tacky on a hot summer day, and hard and boardy in cold winter weather?” The deceptive simplicity of this question probably inspired the hope, which has come down almost to the present day, that the secrets of vulcanization and even of the elasticity of rubber could be explained in terms of the properties and reactions of simple organic molecules, such as the reactions of sulfur with simple olefins. The vast increase in the knowledge of giant molecules during the past decade has shattered any basis there may have been for such a hope, but occasional articles show that this desire for simplicity continues to live and to color our thinking on this problem. This paper discusses some of the inherent limitations of the old, simpler pictures of vulcanization and the structure of rubber, and some of the implications of the present view that crude rubber is built up of giant molecules. Probably there are not merely one or two or half a dozen reactions, but rather there are literally millions of possible vulcanization reactions, each of which may influence the physical properties of the rubber. The study of these reactions will require new and far more sensitive methods of physical and chemical analysis than have been available heretofore, as well as new points of view in interpreting the data.

ALGOMA AR225

Alloy Digest ◽  
2003 ◽  
Vol 52 (12) ◽  
Keyword(s):  
Carbon Steel ◽  
Chemical Analysis ◽  
Physical Properties ◽  
Carbon Content ◽  
Brinell Hardness ◽  
Low Cost ◽  
Heat Treating ◽  
Rolled Plate ◽  
High Carbon ◽  
High Carbon Content

Abstract Algoma AR225 is a carbon steel developed primarily to supply a low-cost material for high-abrasion applications. It is furnished in the form of as-rolled plate with a relatively high carbon content (0.35-0.45%). AR-225 is sold on the basis of chemical analysis only; the number 225 signifies the approximate Brinell hardness. On thicknesses one-half inch and over, this Brinell value may be lower than 225 because of higher finishing temperatures. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on forming, heat treating, machining, and joining. Filing Code: CS-138. Producer or source: Algoma Steel Corporation Ltd.

scholarly journals Chemical and Physical Properties of Some Hazelnut Varieties Grown in Portugal

Agronomy ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1476
Author(s):  
Ana Cristina Ferrão ◽  
Raquel P. F. Guiné ◽  
Elsa Ramalhosa ◽  
Arminda Lopes ◽  
Cláudia Rodrigues ◽  
...  
Keyword(s):  
Discriminant Analysis ◽  
Physical Properties ◽  
Water Activity ◽  
Induction Time ◽  
Oxidation Stability ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Nutritional Characteristics ◽  
Physical And Chemical ◽  
And Chemical Properties

Hazelnuts are one of the most appreciated nuts worldwide due to their unique organoleptic and nutritional characteristics. The present work intended to analyse several physical and chemical properties of different hazelnut varieties grown in Portugal, namely Tonda de Giffoni, Grada de Viseu, Segorbe, Longa de Espanha, Butler, Gunslebert, and Negreta. In general, the results revealed statistically significant differences between the varieties under study. The Gunslebert had more elongated hazelnuts and with heavier shelled fruits, while the kernels of the Grada de Viseu revealed to be heavier. Grada de Viseu was harder in the shell, Gunslebert had a harder core, and Segorbe was more resistant to fracture. Fat was the more representative component for all varieties and in some cases the values of moisture and water activity were over the recommended amount (≥0.62). Tonda de Giffoni was the variety with the highest induction time, indicating the highest oxidation stability. Moreover, discriminant analysis revealed that the variables more important to distinguish the varieties were protein (λ = 0.007) and water activity (λ = 0.010). The results of this study help to better understand the differences between some hazelnut varieties that are cultivated in Portugal, which gives important hints for all players in the hazelnut sector.

scholarly journals Effect of Mosses on physical and chemical properties of soil in temperate forests of Garhwal Himalayas

2021 ◽  
pp. 1-10
Author(s):  
Anshu Siwach ◽  
Siddhartha Kaushal ◽  
Ratul Baishya
Keyword(s):  
Physical Properties ◽  
Chemical Properties ◽  
Nutrient Status ◽  
High Rate ◽  
Physical And Chemical Properties ◽  
Garhwal Himalayas ◽  
Forest Sites ◽  
Significant Difference ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract Mosses are one of the most important and dominant plant communities, especially in the temperate biome, and play a significant role in ecosystem function and dynamics. They influence the water, energy and element cycle due to their unique ecology and physiology. The present study was undertaken in three different temperate forest sites in the Garhwal Himalayas, viz., Triyuginarayan (Kedarnath Wildlife Sanctuary (KWLS)), Chakrata, and Kanasar forest range. The study was focused on understanding the influence of mosses on soil physical properties and nutrient availability. Different physico-chemical properties were analysed under two different substrata, that is, with and without moss cover in two different seasons, viz., monsoon and winter. We observed mosses to influence and alter the physical properties and nutrient status of soil in both seasons. All soil physical and chemical properties, except magnesium, showed significant difference within the substrates, among all the sites and across the two seasons. Besides the soil characteristics underneath the moss vegetation, the study also highlights the diversity of mosses found in the area. Mosses appear to create high nutrient microsites via a high rate of organic matter accumulation and retain nutrients for longer periods thus, maintaining ecosystem stability.

scholarly journals Not Just Transporters: Alternative Functions of ABC Transporters in Bacillus subtilis and Listeria monocytogenes

2021 ◽  
Vol 9 (1) ◽  
pp. 163
Author(s):  
Jeanine Rismondo ◽  
Lisa Maria Schulz
Keyword(s):  
Bacillus Subtilis ◽  
Listeria Monocytogenes ◽  
Abc Transporters ◽  
Organic Molecules ◽  
Atp Hydrolysis ◽  
The Past ◽  
Wide Range ◽  
Regulatory Functions ◽  
Complex Organic ◽  
Detoxification Mechanisms

ATP-binding cassette (ABC) transporters are usually involved in the translocation of their cognate substrates, which is driven by ATP hydrolysis. Typically, these transporters are required for the import or export of a wide range of substrates such as sugars, ions and complex organic molecules. ABC exporters can also be involved in the export of toxic compounds such as antibiotics. However, recent studies revealed alternative detoxification mechanisms of ABC transporters. For instance, the ABC transporter BceAB of Bacillus subtilis seems to confer resistance to bacitracin via target protection. In addition, several transporters with functions other than substrate export or import have been identified in the past. Here, we provide an overview of recent findings on ABC transporters of the Gram-positive organisms B. subtilis and Listeria monocytogenes with transport or regulatory functions affecting antibiotic resistance, cell wall biosynthesis, cell division and sporulation.

scholarly journals Physicochemical Characteristics of Arginine Enriched NaF Varnish: An In Vitro Study

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2998
Author(s):  
Mohammed Nadeem Bijle ◽  
Manikandan Ekambaram ◽  
Edward Lo ◽  
Cynthia Yiu
Keyword(s):  
Molecular Dynamics ◽  
Physical Properties ◽  
Artificial Saliva ◽  
Chemical Properties ◽  
In Vitro Study ◽  
Physicochemical Characteristics ◽  
Vitro Study ◽  
Physical And Chemical ◽  
Stable Matrix

The in vitro study objectives were to investigate the effect of arginine (Arg) incorporation in a 5% sodium fluoride (NaF) varnish on its physical and chemical properties including F/Arg release. Six experimental formulations were prepared with L-arginine (L-Arg) and L-arginine monohydrochloride at 2%, 4%, and 8% w/v in a 5% NaF varnish, which served as a control. The varnishes were subjected to assessments for adhesion, viscosity, and NaF extraction. Molecular dynamics were simulated to identify post-dynamics total energy for NaF=Arg/Arg>NaF/Arg<NaF concentrations. The Arg/F varnish release profiles were determined in polyacrylic lactate buffer (pH-4.5; 7 days) and artificial saliva (pH-7; 1 h, 24 h, and 12 weeks). Incorporation of L-Arg in NaF varnish significantly influences physical properties ameliorating retention (p < 0.001). L-Arg in NaF varnish institutes the Arg-F complex. Molecular dynamics suggests that NaF>Arg concentration denotes the stabilized environment compared to NaF<Arg (p < 0.001). The 2% Arg-NaF exhibits periodic perennial Arg/F release and shows significantly higher integrated mean F release than NaF (p < 0.001). Incorporating 2% L-arginine in 5% NaF varnish improves its physical properties and renders a stable matrix with enduring higher F/Arg release than control.

scholarly journals Biofilm Forming Bacteria during Thermal Water Reinjection

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Máté Osvald ◽  
Gergely Maróti ◽  
Bernadett Pap ◽  
János Szanyi
Keyword(s):  
Thermal Water ◽  
Oxygen Demand ◽  
Geothermal System ◽  
Biological Processes ◽  
Geothermal Systems ◽  
The Past ◽  
Surface System ◽  
Buffer Tank ◽  
Physical And Chemical ◽  
Phenol Index

Reinjection of heat-depleted thermal water has long been in the center of scientific interest in Hungary regarding around 1000 operating thermal wells. While the physical and chemical aspects of reinjection have partly been answered in the past years, the effects of biological processes are still less known. We carried out our investigations in the surface elements of the Hódmezővásárhely geothermal system which is one of the oldest operating geothermal systems in Hungary. About one-third of the used geothermal water has been reinjected since 1998 by two reinjection wells at the end of the thermal loops. During the operation, plugging of the surface system was experienced within a few-day-long period, due to biological processes. The goal of our research was to find the dominant species of the microbial flora and to make a proposal to avoid further bacterial problems. We found that the reinjected, therefore the produced, water’s chemical oxygen demand, phenol index, and BTEX composition basically determine the appearing flora on the surface. When the concentration of these compounds in the thermal water is significant and residence time is long enough in the buffer tank, certain bacteria can be much more dominant than others, thus able to form a biofilm which plugs the surface equipment much more than it is expected.

Effects of physical and chemical structures of bacterial cellulose on its enhancement to paper physical properties

Cellulose ◽  
2017 ◽  
Vol 24 (8) ◽  
pp. 3513-3523 ◽  
Author(s):  
Zhouyang Xiang ◽  
Qingguo Liu ◽  
Yong Chen ◽  
Fachuang Lu
Keyword(s):  
Physical Properties ◽  
Bacterial Cellulose ◽  
Chemical Structures ◽  
Physical And Chemical

scholarly journals Physico Chemical Analysis of Sapota (Manilkara zapota) Coated by Edible Aloe Vera Gel

2015 ◽  
Vol 3 (1) ◽  
pp. 20-25 ◽  
Author(s):  
N. Padmaja ◽  
S. John Don Bosco ◽  
J. Sudhakara Rao
Keyword(s):  
Chemical Analysis ◽  
Aloe Vera ◽  
Ascorbic Acid Content ◽  
Chemical Characteristics ◽  
Manilkara Zapota ◽  
Aloe Vera Gel ◽  
Physico Chemical ◽  
Dramatic Decline ◽  
Physical And Chemical

The physical and chemical characteristics of the fruit have immense significance as they ultimately affect the quality of processed productsprepared from them. Over ripening of Sapota (Manilkara zapota) fruits at the post-harvest stage usually results in dramatic decline in quality.In the present study, physico chemical analysis (which includes Weight loss, Colour, Texture, TSS, pH, TA and Ascorbic acid content) ofedible Aloe vera gel coated Sapota fruits packed in LDPE and stored at 15 ± 2? were studied at regular intervals of 5 days i.e., 0th,5th, 10th,15thand 20th days. The dip treatment of Aloe vera gel coating 1:2, 7 minutes had best retained the physico chemical characteristics than the othertreatments performed and was found to be the most effective treatment in maintaining the fruit quality attributes along with the shelf lifeextension of about 20 days.DOI: http://dx.doi.org/10.3126/ijasbt.v3i1.11703 Int J Appl Sci Biotechnol, Vol. 3(1): 20-25      

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