An Attempt at a Rational Classification of the Principal Accelerators of Vulcanization. II. A Study of the Time Required for Vulcanization Giving the Maxima Physical Properties at Different Temperatures

1930 ◽  
Vol 3 (1) ◽  
pp. 38-50
Author(s):  
R. Thiollet ◽  
G. Martin
Keyword(s):  
Physical Properties ◽  
Prolonged Heating ◽  
Physical Quality ◽  
Gutta Percha ◽  
Different Temperatures ◽  
Time Required ◽  
Rational Classification

Abstract We have attempted to classify the principal accelerators of vulcanization according to their chief characteristics which are the following: (1) Time necessary for the fixation of mixtures at different temperatures. (2) Times required at different temperatures to obtain vulcanization giving the maxima physical properties. (3) Aging. The first of these 3 items has been treated in Caoutchouc et Gutta-Percha (April, 1929) and we have shown how accelerators can be classified by their “precocity” of action; that is to say, by the rapidity with which they “fix” mixtures at different temperatures. The mixture being fixed, vulcanization continues and the physical quality of the rubber improves. It thus reaches a maximum, then diminishes upon too prolonged heating. In this second study we have attempted to determine the following points: (1) At a given temperature, how long a period of vulcanization is required to impart to the mixtures their maxima physical properties? (2) Within the range of temperatures, which temperature gives the optima physical properties?

An Attempt at a Rational Classification of the Principal Accelerators of Vulcanization

1929 ◽  
Vol 2 (3) ◽  
pp. 356-361
Author(s):  
G. Martin ◽  
R. Thiollet
Keyword(s):  
Mechanical Properties ◽  
The Other ◽  
Different Temperatures ◽  
Points Of View ◽  
Time Required ◽  
Rational Classification

Abstract AT the present time there are many accelerators on the market for the vulcanization of rubber, but it is often difficult to choose among them those best suited for a required purpose. Accelerators are often classed as slow medium, rapid and ultra rapid. These brief terms are entirely unsatisfactory for characterizing clearly the properties of these properties, and it frequently happens that two accelerators which have been placed together in one class behave in reality in very different ways and are not entirely replaceable one by the other. The object of this study is to establish a rational classification of the principal accelerators of vulcanization, which is based not only on their activity but also on their other important characteristics. The following points will be considered in their order: (1) The time required for the fixation of mixtures at different temperatures. (2) The time required to bring about vulcanization giving the maxima mechanical properties at different temperatures. (3) Aging. (4) These three points of view will be completed by a study of the plasticizing power and of the influence of different charges on the action of the accelerators.

scholarly journals GUAR GUM ADDITION ON PHYSICAL CHARACTERISTICS OF EXTRUDED DRY CORN NOODLE FROM MIXTURE OF WET AND DRY CORN FLOURS

2020 ◽  
Vol 11 (1) ◽  
pp. 39
Author(s):  
Aminullah Aminullah ◽  
Tjahja Muhandri ◽  
Subarna Subarna
Keyword(s):  
Moisture Content ◽  
Physical Properties ◽  
Shelf Life ◽  
Guar Gum ◽  
Physical Characteristics ◽  
Cooking Loss ◽  
Drying Process ◽  
Corn Flour ◽  
Physical Quality

The drying process of corn noodles was an effort to increase the shelf life and it was a form of noodles diversification. The objective of this research was to study and analyze the effect of guar gum addition on the physical quality of the extruded dry corn noodle made from a mixture of wet and dry corn flour. Manufacturing dry corn noodles was conducted using wet corn noodles from a mixture of wet and dry corn flour, which was then dried in a tray dryer at a temperature of 60-70 °C for 1 - 1.5 hours. The treatments used were a combination of alum levels of 0.01%; moisture content of 80% (dry base); and guar gum concentration of 0%, 1%, and 2%. Physical properties of dry corn noodles included rehydration time, hardness, adhesiveness, suppleness, elongation, and cooking loss. The results showed that the optimum rehydration time for dry corn noodles was about 9 minutes. The addition of guar gum to the physical qualities of dry corn noodles tended not to be significant statistically, but as a score, an increase in guar gum levels tended to increase the elongation of dry corn noodles. While, increasing levels of guar gum tended to reduce the stickiness and cooking loss levels of them.

scholarly journals Qualidade física de grãos beneficiados de cultivares de arroz produzidos em diferentes níveis de adubação

2020 ◽  
Vol 42 ◽  
pp. 29
Author(s):  
Amanda Müller ◽  
Paulo Carteri Coradi ◽  
Jonatas Ibagé Steinhaus ◽  
Guilherme Abreu Coelho de Souza ◽  
Letícia Oliveira Carneiro ◽  
...  
Keyword(s):  
Whole Grains ◽  
Quality Analysis ◽  
Average Yield ◽  
Soil Fertilization ◽  
Physical Quality ◽  
Polished Rice ◽  
Physical Classification ◽  
Different Levels

Rice is one of the most cultivated cereals in the world and the increase in crop yield is associated with cultivars and levels of soil fertilization, and may suffer changes in grain quality after processing. The objective of this work was to evaluate the physical quality of grains of rice benefited as polished and integral of cultivars IR 424 RI and IR 431 CL as a function of different levels of fertilization. After the harvest, the grains were subjected to the debarking and polishing processes. Quality analysis was performed according to the physical classification of rice. The cultivar IR 424 RI obtained higher values of yellow, burned and plastered grains, and in the cultivar IR 431 LC more broken, chopped and stained grains were observed. The average yield of polished rice of cultivar IR 431 CL was 44.54% and cultivar IR 424 RI was 56.80%. Meanwhile, the average yield of whole rice of cultivar IR 431 CL was 65.02% and cultivar IR 424 RI was 73.08%. The increase in the fertilization levels of the rice influenced positively on the yield of whole grains, but did not present satisfactory results regarding the physical quality.

scholarly journals Effect of Heat Softening versus Ultrasonic Removal of Root-End Gutta-Percha on the Quality of Root-End Preparation for Endodontic Microsurgery

Scanning ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zhiting Ling ◽  
Ziting Zheng ◽  
Yuting Zeng ◽  
Lifang Jiang ◽  
Yuan Wu ◽  
...  
Keyword(s):  
Root Apex ◽  
Root Surface ◽  
Preparation Time ◽  
Marginal Integrity ◽  
Endodontic Microsurgery ◽  
Gutta Percha ◽  
Wilcoxon Rank Sum Test ◽  
Time Required ◽  
End Resection

This study is aimed at comparing the efficacy of heat softening and ultrasonic removal of root-end gutta-percha during retrograde preparation for root apical microsurgery. Recently extracted single-rooted premolars ( n = 40 ) were prepared with standardized endodontically treated and root-end resection and then randomly divided into four groups that received root-end cavity preparation using four different instruments: a diamond-coated ultrasonic tip (AS3D; SACTEON, Paris, France), AS3D with the modified plugger of cordless heat carrier (MSE; B&L Biotech, Bala Cynwyd, PA, USA), stainless steel ultrasonic tip (Jetip-2; B&L Biotech, Bala Cynwyd, PA, USA), or Jetip-2 with MSE. The time required for root-end preparation was recorded. The root apex samples were examined by scanning electron microscopy to assess root surface microcracks and marginal integrity. The remnants of gutta-percha on the cavity walls were evaluated using a stereomicroscope. Statistical analysis was performed using Student’s t -test and Wilcoxon rank-sum test ( P < 0.05 ). Usage of MSE with Jetip-2 significantly reduced preparation time from 99.8 ± 6.8   s to 32.4 ± 1.0   s ( P = 0.009 ), the number of microcracks from 42 to 13 ( P = 0.036 ), and the remnants of gutta-percha from 80% to 20% ( P = 0.041 ). Similar results were observed for AS3D with MSE. The heat softening of MSE was effective in cleaning gutta-percha, thus greatly improving the efficiency of the root-end preparation, thereby producing a root-end cavity with fewer microcracks and better marginal integrity.

scholarly journals Utility of microcalorimetry in describing the growth curve of C. albicans at different temperatures – indentifying the optimal growth temperature

2019 ◽  
Vol 2 (2) ◽  
pp. 69-74
Author(s):  
Mihnea Popa ◽  
Vlad Popa ◽  
Bogdan Şerban ◽  
Radu Nedelcu ◽  
Bogdan Creţu ◽  
...  
Keyword(s):  
Optimal Growth ◽  
Anaerobic Microorganism ◽  
Medical Specialties ◽  
Artificial Joints ◽  
Frequent Use ◽  
Different Temperatures ◽  
Good Biocompatibility ◽  
Materials Used ◽  
Time Required

AbstractIn comparison with other medical specialties, Orthopedics and Traumatology are continuously impressively developing, intrinsically connected to technological evolution. More than in other fields, in Orthopedics and Traumatology, the technological progress becomes obvious also by the frequent use of implants or osteosynthesis materials. By performing a simple search in the specialty literature, an exponential growth of arthroplasty surgeries in correlation with the life span of the population and implying a need that presupposes the increase of the quality of life, also by maintaining or improving mobility at a satisfying level, can be observed. At the same time, due to the increase in the number of traffic and sports accidents, the use of artificial joints and implants for osteosynthesis will constantly rise. The prostheses and the osteosynthesis materials used for the treatment of degenerative, traumatic or even esthetic pathologies are made of materials with a good biocompatibility.Candida albicans is an optional anaerobic microorganism so the experiments performed with different volumes of environment were most likely influenced by the amount of oxygen, nutrient.In the described research, we demonstrated that, using microcalorimetry, it is possible to identify this fungus in half the time required for classical microbiological identification. In addition, as our team has shown, there is the possibility of real-time antifungigram by using microcalorimetry.

scholarly journals Coffee (Coffea sp.) hull waste fermentation with the addition of banana sucker microorganism activator for physical quality of Ruminantia feed

2021 ◽  
Author(s):  
T Karyono ◽  
R Novita
Keyword(s):  
Physical Properties ◽  
Analysis Of Variance ◽  
Physical Characteristics ◽  
Physical Quality ◽  
Silage Fermentation ◽  
Randomized Design ◽  
Hull Waste ◽  
Effect Of Treatment ◽  
Ruminant Feed

This research aims to determine the physical quality of coffee hull waste fermentation using a banana sucker microorganism activator. It aims to determine the best composition of banana sucker local microorganism (MOL) activator. Method used in this research was complete randomized design consisting of 6 levels and 4 replications which are, F1 = 10 ml MOL / 1 kg coffee hull, F2 = 15 ml MOL / 1 kg coffee hull, F3 = 20 ml MOL / 1 kg coffee hull, F4 = 25 ml MOL / 1 kg coffee hull, F5 = 30 ml MOL / 1 kg coffee hull, F6 = 35 ml MOL / 1 kg coffee hull. Silage fermentation physical characteristics observed are acidity/PH, aroma/smell, color, and texture. These characteristics were examined in this research to determine the effect of treatment. The data obtained were analyzed by analysis of variance and further HSD test. The results of the research that the addition of banana sucker microorganism activator to the fermentation of coffee hull waste (coffea sp) on physical quality for ruminant feed showed no significant effect (P> 0.05) on pH, color, and texture and had a very significant effect (P <0, 01) on the aroma. It can be concluded that the addition of banana sucker microorganism activator in the fermentation of coffee hull gave the best aroma results in the F4 treatment (3.29) and gave equally good results on physical properties such as pH, color, and texture of the fermented coffee hull.

The Utilization of Red Dragon Fruit Peel Extract (Hylocereus costaricencis) As A Natural Colorant of Dried Noodle

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Silaturahmi Silaturahmi ◽  
Zaidiyah Zaidiyah ◽  
Tengku Mia Rahmiati
Keyword(s):  
Product Diversification ◽  
Fruit Peel ◽  
Physical Quality ◽  
Natural Colorant ◽  
Randomized Design ◽  
Solid Loss ◽  
Dragon Fruit ◽  
Completely Randomized Design ◽  
Peel Extract

The use of colorants in the dried noodle manufactures is an effort of product diversification. Besides of being used as a natural coloring agent, this peel extract is also used to improve nutritional value of the expected product. The purpose of this study was to determine the effect of red dragon fruit peel extract on the physical quality of dried noodle.  The study was conducted by using Completely Randomized Design (CRD) method with one factor, namely concentration of red dragon fruit peel extract (N1 = 10 ml, N2 = 15 ml, N3 = 20 ml, N4 = 25 ml, N5 = 30 ml).  The observations of its physical quality consisted of water absorption, solid loss during cooking, and organoleptic tests (aroma and color).  The best quality of dried noodle was obtained by using 30 ml red dragon fruit peel extract (N5) with physical properties, namely DSA levels of 351.92%, solid loss during cooking 4.78%, aroma 3.79 (like) and color 3.89 (like).

Dynamics of the processes in metal machining

1998 ◽  
Vol 2 ◽  
pp. 115-122
Author(s):  
Donatas Švitra ◽  
Jolanta Janutėnienė
Keyword(s):  
High Frequency ◽  
Machine Tools ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Low Frequency ◽  
Metal Cutting Machine ◽  
Cutting Machine ◽  
Metal Machining

In the practice of processing of metals by cutting it is necessary to overcome the vibration of the cutting tool, the processed detail and units of the machine tool. These vibrations in many cases are an obstacle to increase the productivity and quality of treatment of details on metal-cutting machine tools. Vibration at cutting of metals is a very diverse phenomenon due to both it’s nature and the form of oscillatory motion. The most general classification of vibrations at cutting is a division them into forced vibration and autovibrations. The most difficult to remove and poorly investigated are the autovibrations, i.e. vibrations arising at the absence of external periodic forces. The autovibrations, stipulated by the process of cutting on metalcutting machine are of two types: the low-frequency autovibrations and high-frequency autovibrations. When the low-frequency autovibration there appear, the cutting process ought to be terminated and the cause of the vibrations eliminated. Otherwise, there is a danger of a break of both machine and tool. In the case of high-frequency vibration the machine operates apparently quiently, but the processed surface feature small-sized roughness. The frequency of autovibrations can reach 5000 Hz and more.

Paepalanthus fabianeae (Eriocaulaceae): A New Microendemic Species from a Morphologically Coherent Clade

2020 ◽  
Vol 45 (4) ◽  
pp. 794-801
Author(s):  
Caroline Oliveira Andrino ◽  
Marcelo Fragomeni Simon ◽  
Jair Eustáquio Quintino Faria ◽  
André Luiz da Costa Moreira ◽  
Paulo Takeo Sano
Keyword(s):  
New Species ◽  
Iucn Red List ◽  
Phylogenetic Position ◽  
Similar Species ◽  
Infrageneric Classification ◽  
Espinhaço Range ◽  
Nuclear Its ◽  
Two Populations

Abstract—We describe and illustrate Paepalanthus fabianeae, a new species of Eriocaulaceae from the central portion of the Espinhaço Range in Minas Gerais, Brazil. Previous phylogenetic evidence based on analyses of nuclear (ITS and ETS) and plastid (trnL-trnF and psba-trnH) sequences revealed P. fabianeae as belonging to a strongly supported and morphologically coherent clade containing five other species, all of them microendemic, restricted to the Espinhaço range. Due to the infrageneric classification of Paepalanthus being highly artificial, we preferred not assigning P. fabianeae to any infrageneric group. Paepalanthus fabianeae is known from two populations growing in campos rupestres (highland rocky fields) in the meridional Espinhaço Range. The species is characterized by pseudodichotomously branched stems, small, linear, recurved, and reflexed leaves, urceolate capitula, and bifid stigmas. Illustrations, photos, the phylogenetic position, and a detailed description, as well as comments on habitat, morphology, and affinities with similar species are provided. The restricted area of occurrence allied with threats to the quality of the habitat, mainly due to quartzite mining, justifies the preliminary classification of the new species in the Critically Endangered (CR) category using the guidelines and criteria of the IUCN Red List.

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