Retraction Test for Serviceability of Elastomers at Low Temperatures

1951 ◽  
Vol 24 (3) ◽  
pp. 684-696 ◽  
Author(s):  
O. H. Smith ◽  
W. A. Hermonat ◽  
H. E. Haxo ◽  
A. W. Meyer
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Room Temperature ◽  
Large Deformations ◽  
Prolonged Storage ◽  
Temperature Index ◽  
Low Temperature Storage ◽  
Compression Set ◽  
Low Temperature Flexibility ◽  
Temperature Storage

Abstract Elastomer vulcanizates progressively stiffen as the temperature is lowered. Additional stiffening, due to crystallization, may occur as exposure to low temperatures is prolonged. The available methods of testing the low temperature flexibility of rubber and rubberlike materials do not reveal the losses in flexibility caused by crystallization except by using prolonged storage at low temperatures. A retraction test employing large deformations, which greatly increases the rate of crystallization, has been developed. This test rapidly gives a temperature index correlating with the stiffness of elastomer vulcanizates after storage at low temperatures, and can be used to measure the merit for low temperature applications of both crystallizable and noncrystallizable elastomers. This test in conjunction with conventional (room temperature) tests has been used successfully to study the low temperature performance of Hevea, GR-S, Paracril, and polybutadiene vulcanizates along with vulcanizates of many experimental elastomers. Correlation of results with cold compression set and hardness after low temperature storage has been excellent and substantiates the usefulness of the test.

scholarly journals THE PROPERTIES OF THE CONIDIA OF STRAINS OF THE ACTINOMYCETE STREPTOMYCES LUCENSIS AND STREPTOMYCES VIOLACEUS DURING STORAGE AT LOW TEMPERATURES

Food systems ◽  
2018 ◽  
Vol 1 (3) ◽  
pp. 27-32 ◽  
Author(s):  
Natalya Yu. Sharova ◽  
Tatyana V. Vybornova ◽  
Anastasia A. Printseva ◽  
Bairta S. Manzhieva
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Saline Solution ◽  
Native Solution ◽  
Aqueous Sodium Chloride Solution ◽  
Glycerin Solution ◽  
Low Temperature Storage ◽  
Temperature Storage

Collection cultures of actinomycetes are mainly stored in a dried state on adsorbents. Practiced low-temperature storage of actinomycetes at minus 70°C. The article presents the results of investigations of the properties of the conidia of strains of the actinomycete Streptomyces lucensis VKPM Ac–1743 and Streptomyces violaceus VKPM Ac–1734 is in the process of storage at minus 12°C and minus 18°C in glycerin solution and in 0,9 % aqueous sodium chloride solution. It was found that the inhibitory activity in the native solution for the studied strains stored in the glycerin solution at minus 12°C and plus 4°C, as a result of their subsequent cultivation on the starch hydrolyzate for 120 h is at the level of (450 ± 10) IE/cm3. The indicator for crops stored at minus 18°C was higher (560 ± 10) IE/cm3. Low-temperature storage of conidia in saline solution is less effective. Pigmentation is more active in the cultivation of strains stored at minus 18°C.

Effect of Storage and Temperature on Flexibility of Natural and Synthetic Rubbers

1948 ◽  
Vol 21 (4) ◽  
pp. 864-876
Author(s):  
John B. Gregory ◽  
Irving Pockel ◽  
John F. Stiff
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Strain Curve ◽  
Polymer Chains ◽  
Stress Strain Curve ◽  
Low Temperature Storage ◽  
Synthetic Rubber ◽  
Loading And Unloading ◽  
Temperature Storage ◽  
Natural And Synthetic

Abstract A new method for measuring the flexibility of rubber has been described. The method consists essentially in determining the stress-strain curve obtained by loading and unloading a loop formed from a one-inch by six-inch strip cut from a test slab. A coefficient of flexibility independent of the thickness of the sample and, in addition, information on per cent resilience were obtained. By the use of the method described, the behavior of various natural and synthetic rubber gas mask facepiece compounds was studied during one month to three months' exposure at various temperatures down to −20° F. Progressive stiffening probably due to crystallization was found for natural rubber, GR-I, and GR-M compounds at low temperatures. No tendency to crystallize was noted for the GR-S compound. Of the crystallizable polymers GR-I was the most resistant, and GR-M the least resistant to stiffening during low temperature storage. It is of course evident that different polymers have inherently different degrees of resistance to low temperatures. Disregarding these inherent differences the work reported indicates that the resistance of elastomer compounds to stiffening during prolonged low temperature storage is favored by the following: 1. Use of interpolymers made from monomer mixtures having a relatively large proportion of each component, thus obtaining mutual intereference with crystallization. 2. Use of a “tight” cure which probably so impedes the movement of the polymer chains as to make crystallization difficult.

scholarly journals Perubahan Mutu Tomat (Lycopersicon esculentum Mill.) Dengan Variasi Konsentrasi Pelapisan Gel Lidah Buaya (Aloe vera L.) Dan Suhu Penyimpanan

2016 ◽  
Vol 1 (1) ◽  
pp. 985-994
Author(s):  
Rina Marwina ◽  
Raida Agustina ◽  
Bambang Sukarno Putra
Keyword(s):  
Weight Loss ◽  
Low Temperature ◽  
Vitamin C ◽  
Room Temperature ◽  
Storage Temperature ◽  
Aloe Vera ◽  
Low Temperature Storage ◽  
Aloe Vera Gel ◽  
Aloe Gel ◽  
Temperature Storage

Abstrak.Penelitian ini bertujuan untuk melihat lama umur simpan buah tomat dengan menggunakan lapisan gel lidah buaya (Aloe vera L.) dengan berbagai variasi konsentrasi dan variasi suhu penyimpanan.Penelitian ini menggunakan tomat dengan tingkat kematangan optimum. Pada variasi konsentrasi gel lidah buaya (A) terdiri atas 4 perlakuan, yaitu tanpa gel lidah buaya (A1), konsentrasi 30% (A2), konsentrasi 50% (A3) dan konsentrasi 70% (A4), dan variasi penyimpanan yaitu suhu penyimpanan (B) terdiri atas 2 perlakuan, yaitu suhu B1 suhu ruang  (28oC) dan  B2 (suhu rendah 10oC ). Analisa data yang diamati meliputi susut bobot, kekerasan, vitamin C, total padatan terlarut, dan uji organoleptik (warna, tekstur, dan aroma).Dari hasil penelitian didapatkan perlakuan terbaik pada tomat dengan perlakuan konsentrasi gel lidah buaya 30% pada penyimpanan suhu rendah 10ºC masih diterima konsumen hingga hari ke 21. Penyimpanan perlakuan terbaik pada hari ke-12 untuk analisis susut bobot terdapat pada perlakuan konsentrasi gel lidah buaya 30% yang disimpan pada suhu 10ºC dengan nilai 15,52%, untuk analisis presentase kekerasanperlakuan terbaik terdapat pada konsentrasi 30% pada suhu rendah 10ºCnilai yaitu 1.357kg/cm2, dan analisis vitamin C perlakuan terbaik terdapat pada konsentrasi 30% pada suhu rendah 10ºCnilai 1,42 mg/50gr, sedangkan TPT perlakuan terbaik terdapat pada suhu rendah 10ºCdengan perlakuan tanpa konsetrasi gel lidah buaya nilai presentase yaitu 4,40 %Brix. Dari hasil pengujian organoleptik, panelis menolak tomat dengan perlakuan konsentrasi gel lidah buaya 30% yang disimpan pada suhu ruang 28oC pada hari penyimpanan ke-12, sedangkan pada penyimpanan suhu rendah 10oC panelis menolak tomatdengan konsentrasi gel lidah buaya 30%pada hari penyimpanan ke-21.Abstract. This study aimed to look at the old the shelf life of tomatoes by using the layer of gels of aloe vera (Aloe vera L.) with various concentrations and a temperature variations in of storage.This study uses the tomatoes with optimum maturity level. In a variation of concentration of aloe gel (A) composed of 4 treatment, ie without aloe vera gel (A1), the concentration of 30% (A2), the concentration of 50% (A3) and a concentration of 70% (A4), and a variety of storage ie storage temperature (B) consisting of two treatments, namely B1 temperature room temperature (28oC) and B2 (low temperature 10oC). Analysis of observed data include weight loss, violence, vitamin C, total dissolved solids, and organoleptic (color, texture, and aroma). From the results, the best treatment in tomatoes by treatment with 30% aloe vera gel at low temperature storage is still acceptable to consumers 10ºC until the 21st day storage best treatment on day 12 for analysis of weight loss treatment concentration contained in aloe vera gel 30% stored at a temperature of 10ºC with a value of 15.52%, for the analysis of the percentage of violence are the best treatment at a concentration of 30% at low temperature 10ºC value is 1,357 kg / cm2, and the analysis of vitamin C are the best treatment at a concentration of 30% at low temperature 10ºC value 1.42 mg / 50gr, while TPT best treatment there at low temperature 10ºC with treatment without concentration of aloe gel percentage value that is 4.40% Brix. From the results of organoleptic tests, the panel rejected the tomatoes by treatment with 30% aloe vera gel is stored at room temperature 28oC on the 12th day of storage, while the low temperature storage 10oC panelists refused tomatoes with aloe vera gel concentration of 30% on the day of deposit of the 21.

scholarly journals Modification of placenta blood serum proteins under low temperature effect

2013 ◽  
Vol 59 (2) ◽  
pp. 219-234
Author(s):  
O.V. Falko ◽  
N.G. Zemlianskykh ◽  
O.V. Lipina ◽  
O.S. Procopyuk
Keyword(s):  
Low Temperature ◽  
Blood Serum ◽  
Low Temperatures ◽  
Structural Changes ◽  
Serum Proteins ◽  
Protein Structures ◽  
Aggregate Formation ◽  
Low Temperature Storage ◽  
Blood Serum Proteins ◽  
Temperature Storage

Changes in environmental physical and chemical factors upon freeze-thawing and low temperature storage of biological samples can result in impairments of protein structures. This work specifies spontaneous and diamide-induced protein aggregations of placenta blood serum stored at -20° and -196°C during 2 years with SDS-PAGE. It was shown that storage of placenta blood serum at low temperatures did not cause any quantitative and qualitative changes in fraction distribution of proteins denatured with SDS in comparison to the native samples which were not frozen. Application of b-mercaptoethanol revealed that placenta blood serum proteins upon freeze-thawing did not form spontaneous aggregates linked by disulphide bridges. Oxidation of amino acid sulfhydryl groups induced by diamide and accompanied by high molecular aggregate formation proved to be a quite effective way for indirect estimation of structural changes in protein upon low temperature effects. In samples thawed after low temperature storage the protein aggregation with 4 mM diamide was significantly higher than in native serum. These discrepancies between native and frozen-thawed samples are stipulated by impairments of protein structure under low temperature and increased in accessibility of reactive SH-groups of proteins for oxidation with diamide. Structural changes in placenta blood serum proteins, which caused by low temperatures and revealed by elevated sensibility to diamide-induced aggregate formation, did not depend on temperature (-20° и -196°C) and storage terms (2 years and 3 weeks). They reflect protein reaction to freeze-thawing processes and could be sequence of ice crystal formation which takes place in unprotected media.

A multifactorial study of conditions influencing longevity of neem (Azadirachta indica) seeds

1998 ◽  
Vol 8 (4) ◽  
pp. 473-482 ◽  
Author(s):  
Moctar Sacandé ◽  
Folkert A. Hoekstra ◽  
Jaap G. van Pijlen ◽  
Steven P. C. Groot
Keyword(s):  
Low Temperature ◽  
Azadirachta Indica ◽  
Low Temperatures ◽  
Oil Content ◽  
Metabolic Stress ◽  
Neem Seed ◽  
Low Temperature Storage ◽  
Open Storage ◽  
Extreme Sensitivity ◽  
Temperature Storage

AbstractThe longevity of neem, Azadirachta indica, seeds from African Sahelian (Burkina Faso) and Asian (Sri Lanka) provenances was studied over two years of storage under different conditions of moisture and temperature. After drying to equilibrium moisture content (MC) at different relative humidities at 20°C, seeds were placed in open storage at 20°C or hermetically sealed in packets at temperatures ranging from −20 to +20°C. There was hardly any difference in storage behaviour between seed batches / lots, whatever their provenance. Seeds originating from mature yellow fruits lived longer than seeds from green or brown fruits. In all storage experiments with seeds having MCs ≥ 10%, viability was preserved best at 10−15°C, indicating that neem seed is chilling (and freezing) sensitive. There was no survival longer than 2 years under these conditions. At MCs of 4–8%, seeds were considerably more tolerant of low temperature storage and had 40–60% viability after 2 years at all temperatures tested (−20 to +20°C). However, the seeds were sensitive to imbibitional stress, which could be alleviated by imbibition at temperatures of 25–30°C or above. The difficult storage behaviour of neem seed seems to stem from: (1) the sensitivity to low temperatures at MCs ≥ 10%; (2) the extreme sensitivity to imbibitional stress after storage at ≤ 8% MC; (3) underestimation of the water activity due to the high oil content of the neem seeds, causing unexpected metabolic stress in the higher MC and temperature range.

scholarly journals PHYSICAL CHANGES OF ANDALIMAN (ZANTHOXYLUM ACANTHOPODIUM DC.) IN PACKAGING DURING LOW-TEMPERATURE STORAGE

AGROINTEK ◽  
2019 ◽  
Vol 13 (2) ◽  
pp. 177-182
Author(s):  
David Septian Sumanto Marpaung ◽  
Raizummi Fil'aini ◽  
Amna Citra Fahrani ◽  
Dwi Cahyani ◽  
Ayu Oshin Yap Sinaga
Keyword(s):  
Low Temperature ◽  
Room Temperature ◽  
Aluminum Foil ◽  
Room Temperature Storage ◽  
Postharvest Losses ◽  
Low Temperature Storage ◽  
Long Time ◽  
Postharvest Handling ◽  
Physical Changes ◽  
Temperature Storage

Zanthoxylum acanthopodium, locally known as Andaliman, is exotic spices which grown in North Sumatera. Several investigation shown that the special taste and aroma comes from pericarp of Andaliman. However, the pericarp of Andaliman is easily degraded. The proper postharvest handling of Andaliman is necessary to preserve fresh Andaliman for long time. Previously, Andaliman has been preserved in packaging under room temperature storage. Further investigation of Andaliman preservation in packaging under low temperature storage would help reduces the postharvest losses. In this study, the physical changes of Andaliman in various packaging under low-temperature storage were observed. The results shown that within 2 days, the pericarp of Andaliman in paper packaging was shrunk, similarly found in control without packaging. Meanwhile, the pericarp of Andaliman in aluminum foil and PP plastic were found normal in day 3. This result indicated that in low-temperature, Andaliman in Aluminum foil was recommended for best postharvest handling.

scholarly journals KARAKTERISASI KEJU DANGKE MENGGUNAKAN ENZIM PAPAIN KOMERSIAL DAN PERUBAHAN FISIK SELAMA PENYIMPANAN

2021 ◽  
Vol 32 (1) ◽  
pp. 27-35
Author(s):  
Nurul Ilmi Musra ◽  
◽  
Serdanawati Yasni ◽  
Elvira Syamsir ◽  
Keyword(s):  
Low Temperature ◽  
Room Temperature ◽  
Bitter Taste ◽  
Raw Materials ◽  
Buffalo Milk ◽  
Taste Intensity ◽  
Room Temperature Storage ◽  
Low Temperature Storage ◽  
South Sulawesi ◽  
Temperature Storage

Dangke is one of the traditional cheeses made from buffalo milk or cow's milk from Enrekang, South Sulawesi,. This research aimed to obtain dangke cheese through a process using commercial papain as the curdling agent and to determine the best products based on the analysis of physical properties of the raw materials and the dangke. The dangke making was conducted using several concentrations of the commercial papain (0.2-5%). Based on the texture, yield and non-bitter taste intensity, the best dangke was obtained using 1, 3, and 5% commercial papain. Dangke made using 1, 3, and 5% commercial papain resulted in yields of 18, 17, and 18%, respectively with compact texture and non-bitter taste. At room temperature storage (±30°C), the dangke had shelf life of less than 24 hours, while at low temperature storage (±4°C), dangke could last for four days.

Induction of chill-induced ripening in Fuji apples is a function of both temperature and time

2003 ◽  
Vol 43 (10) ◽  
pp. 1255 ◽  
Author(s):  
J. Jobling ◽  
R. Pradhan ◽  
S. C. Morris ◽  
N. L. Wade
Keyword(s):  
Carboxylic Acid ◽  
Low Temperature ◽  
Low Temperatures ◽  
Acid Oxidase ◽  
Continuous Exposure ◽  
Controlled Atmosphere ◽  
Practical Solution ◽  
Low Temperature Storage ◽  
Increased Activity ◽  
Temperature Storage

Ethylene production is stimulated by chilling in some cultivars of apples, citrus, cucumbers and pears. The apple varieties Granny Smith, Lady Williams and Fuji can be induced to ripen by a period of chilling at 0°C in air, which hastens the onset of the rise in ethylene production.Fuji apples were susceptible to rapid ripening if stored in air at low temperatures (<10°C). The induction of rapid ripening occurred in both early and late harvested fruit and was correlated with increased activity of 1-aminocyclopropane-1-carboxylic acid oxidase during low temperature storage. The induction of rapid ripening caused the fruit to soften more quickly after cold storage than after continuous exposure to 20°C. Rapid ripening could be prevented by storing fruit in controlled atmosphere (CA) storage (2%�O2 and <1% CO2). Fruit had lower internal ethylene levels following CA storage than following low temperature air storage. The practical solution for growers would therefore be to store Fuji apples in CA, even for short periods, to optimise fruit quality for the consumer.

The effect of low temperature on preparasitic juveniles of Romanomermis (Nematoda: Mermithidae)

Nematology ◽  
1999 ◽  
Vol 1 (5) ◽  
pp. 507-511
Author(s):  
Yufang Peng ◽  
Yi Song ◽  
Jinzhang Song ◽  
Edward G. Platzer
Keyword(s):  
Low Temperature ◽  
Survival Time ◽  
Low Temperatures ◽  
Field Tests ◽  
Low Temperature Storage ◽  
Temperature Storage

Abstract This study showed that at low temperatures (-2 to 2C), more than 90% of the preparasitic juveniles of Romanomermis yunanensis and Romanomermis sp. survived for 8 and 5 days, respectively, but at 26 to 28 C and 16 to 18 C, the 90% survival time for preparasites of these species was 24 and 48 h, respectively. The percentage of mosquitoes infected by preparasites of R. yunanensis maintained at low temperature for 8-11 days was 87.5-94.3%. Preparasites of Romanomermis sp. maintained for 5 days at low temperature infected 81.5 and 55.1% of the mosquitoes in the laboratory and field tests, respectively. This infectivities were not significantly different (P > 0.05) from the pre-storage values. This data indicates that low temperature storage prolonged the survival time and had no effect on the infectivity of the preparasitic juveniles of these Romanomermis species. Effet de basses temperatures sur les juveniles infestants de Romanomermis (Nematoda: Mermithidae)- La presente etude montre qu'a basse temperature (de- 2 a + 2 C) plus de 90% des juveniles preparasites de Romanomermis yunanensis et Romanomermis sp. survivent, respectivement, 8 et 5 jours tandis qu'entre 26 et 28 C ou 16 et 18 C leur survie n'est que de 24 et 48 h, respectivement. Le pourcentage des moustiques infestes par les juveniles preparasites de R. vunanensis maintenus a basse temperature pendant 8 a 11 jours variait de 87,5 a 94,3%. Les juveniles preparasites de Romanomermis sp. maintenus 5 jours a basse temperature infestent 81,5% de moustiques lors de tests au laboratoire et 55,1% lors de tests au champ. Ces taux d'infestivite ne sont pas significativement differents (P > 0 . 05) de ceux releves avant stockage. Ces donnees indiquent que le stockage a basse temperature prolonge le temps de survie des juveniles preparasites de ces especes de Romanomermis et n'a aucun effet sur leur infestivite.

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