Conductivities of Room Temperature Molten Salts Containing ZnCl2, Measured by a Computerized Direct Current Method

2002 ◽  
Vol 57 (3-4) ◽  
pp. 129-135
Author(s):  
Hsin-Yi Hsu ◽  
Chao-Chen Yang
Keyword(s):  
Activation Energy ◽  
Direct Current ◽  
Molten Salts ◽  
Room Temperature ◽  
Current Method ◽  
Cross Linking ◽  
Infra Red ◽  
Different Temperatures ◽  
The Stability ◽  
Benzyltriethylammonium Chloride

The conductivities of the binary room-temperature molten salt (RTMS) systems ZnCl2-N-nbutylpyridinium chloride (BPC), ZnCl2 -1-ethyl-3-methylimidazolium chloride (EMIC) and ZnCl2 - benzyltriethylammonium chloride (BTEAC) have been measured at different temperatures and compositions by a d.c. four-probes method. The conductivities of the three RTMS are in the order ZnCl2-EMIC > ZnCl2-BPC > ZnCl2-BTEAC. In ZnCl2-BPC the conductivity at 70 to 150 °C, is maximal for 40 mol% ZnCl2. In ZnCl2 - EMIC, the conductivity below 130 °C is almost constant for 30 to 50 mol% ZnCl2 and has the lowest activation energy 25.21 kJ/mol. For these two systems, the conductivities decrease rapidly beyond 50 mol% ZnCl2 owing to the rapid increase in cross-linking and resultant tightening of the polyelectrolyte structure. As to the ZnCl2-BTEAC system, the conductivities at 110 - 150 °C decrease slowly for 30 - 60 mol% ZnCl2. The conductivities of the ZnCl2-EMICmelt are compared with those of the AlCl3-EMIC melt previously studied. The stability of the ZnCl2-EMIC melt system is explored by the effect of the environment on the conductivity and the Far Transmission Infra Red (FTIR) spectrum. It reveals that the effect is slight, and that the ZnCl2-EMIC melt may be classified as stable.

Conductivities of Room Temperature Molten Salts Containing AlCl3, Measured by a Computerized Direct Current Method

2001 ◽  
Vol 56 (9-10) ◽  
pp. 670-676
Author(s):  
Hsin-Yi Hsu ◽  
Chao-Cheng Yang
Keyword(s):  
Molten Salt ◽  
Direct Current ◽  
Molten Salts ◽  
Room Temperature ◽  
Current Method ◽  
Activation Energies ◽  
Nium Chloride ◽  
Temperature Range ◽  
Different Temperatures ◽  
Salt Systems

Abstract The conductivities of the binary room-temperature molten salt systems AlCl3-N-n-butylpyridinium chloride (BPC), AlCl3-l-ethyl-3-methylimidazolium chloride (EMIC) and AlCl3-benzyltriethylammo-nium chloride (BTEAC) have been measured at different temperatures and compositions by a d.c. four-probes method. There is a maximum of the conductivity at 50 mol% AlCl3 in the AlCl3-BPC and AlCl3-EMIC systems at 40 to 80 °C, their activation energies being relatively low (20.79 and 14.76 kJ/mol, respec­ tively). As to the A1C13-BTEAC system, there is an irregular change in the conductivity at 40-70 mol% AlCl3 in the temperature range 50 to 80 °C. The conductivities of the three RTMS are in the order AlCl3-EMIC > AlCl3-BPC > AlCl3-BTEAC, the reason being discussed.

scholarly journals Improvement of recovered activity and stability of the Aspergillus oryzae β-galactosidase immobilized on duolite A568 by combination of immobilization methods

2017 ◽  
Vol 23 (4) ◽  
pp. 495-506 ◽  
Author(s):  
Larissa Falleiros ◽  
Bruna Cabral ◽  
Janaína Fischer ◽  
Carla Guidini ◽  
Vicelma Cardoso ◽  
...  
Keyword(s):  
Activation Energy ◽  
Aspergillus Oryzae ◽  
Physical Adsorption ◽  
Cross Linking ◽  
Thermal Deactivation ◽  
Order Model ◽  
First Order ◽  
Immobilized Biocatalyst ◽  
The Stability ◽  
Kinetics Of

The immobilization and stabilization of Aspergillus oryzae ?-galactosidase on Duolite??A568 was achieved using a combination of physical adsorption, incubation step in buffer at pH 9.0 and cross-linking with glutaraldehyde and in this sequence promoted a 44% increase in enzymatic activity as compared with the biocatalyst obtained after a two-step immobilization process (adsorption and cross-linking). The stability of the biocatalyst obtained by three-step immobilization process (adsorption, incubation in buffer at pH 9.0 and cross-linking) was higher than that obtained by two-steps (adsorption and cross-linking) and for free enzyme in relation to pH, storage and reusability. The immobilized biocatalyst was characterized with respect to thermal stability in the range 55-65 ?C. The kinetics of thermal deactivation was well described by the first-order model, which resulted in the immobilized biocatalyst activation energy of thermal deactivation of 71.03 kcal/mol and 5.48 h half-life at 55.0 ?C.

The effect of cross-linking on the elastic modulus of Polythene

1953 ◽  
Vol 218 (1133) ◽  
pp. 245-255 ◽  
Keyword(s):  
Activation Energy ◽  
Elastic Modulus ◽  
Melting Point ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Room Temperature ◽  
Young's Modulus ◽  
Cross Linking ◽  
Flexible Material ◽  
Very High

Young’s modulus for Polythene, cross-linked by pile irradiation, has been measured by both static and dynamic means. Below about 115°C (the usual melting-point) the modulus decreases with temperature. Above this temperature it increases again, in agreement with the theory of rubber-like elasticity, except for very high degrees of cross-linking, corresponding to a glass-like structure. The effect of radiation is both to produce cross-linking, and to destroy crystallinity. The latter effect predominates below about 4% cross-linking, and a more flexible material is obtained at room temperature. The observed elastic properties below 115°C are ascribed in part to the attraction of neighbouring chains; the activation energy required to break these attractive forces is estimated at about 0·25 eV.

scholarly journals Stability of the Combination of Ceftazidime and Cephazolin in Icodextrin or PH Neutral Peritoneal Dialysis Solution

2014 ◽  
Vol 34 (2) ◽  
pp. 212-218 ◽  
Author(s):  
Rahul P. Patel ◽  
Madhur D. Shastri ◽  
Mohammad Bakkari ◽  
Troy Wanandy ◽  
Matthew D. Jose
Keyword(s):  
Peritoneal Dialysis ◽  
Body Temperature ◽  
High Performance ◽  
Room Temperature ◽  
Storage Conditions ◽  
Initial Concentration ◽  
Dialysis Solution ◽  
Different Temperatures ◽  
Colour Changes ◽  
The Stability

IntroductionThe objective of this study was to investigate the stability of ceftazidime and cephazolin in a 7.5% icodextrin or pH neutral peritoneal dialysis (PD) solution.MethodsCeftazidime and cephazolin were injected into either a 7.5% icodextrin or pH neutral PD bag to obtain the concentration of 125 mg/L of each antibiotic. A total of nine 7.5% icodextrin or pH neutral PD bags containing ceftazidime and cephazolin were prepared and stored at 1 of 3 different temperatures: 4°C in a domestic refrigerator; 25°C at room temperature; or 37°C (body temperature) in an incubator. An aliquot was withdrawn immediately before (0 hour) or after 12, 24, 48, 96, 120, 144, 168 and 336 hours of storage. Each sample was analyzed in duplicate for the concentration of ceftazidime and cephazolin using a stability-indicating high-performance liquid chromatography technique. Ceftazidime and cephazolin were considered stable if they retained more than 90% of their initial concentration. Samples were also assessed for pH, colour changes and evidence of precipitation immediately after preparation and on each day of analysis.ResultsCeftazidime and cephazolin in both types of PD solution retained more than 90% of their initial concentration for 168 and 336 hours respectively when stored at 4°C. Both of the antibiotics lost more than 10% of the initial concentration after 24 hours of storage at 25 or 37°C. There was no evidence of precipitation at any time under the tested storage conditions. Change in the pH and color was observed at 25 and 37°C, but not at 4°C.ConclusionPremixed ceftazidime and cephazolin in a 7.5% icodextrin or pH neutral PD solution is stable for at least 168 hours when refrigerated. This allows the preparation of PD bags in advance, avoiding the necessity for daily preparation. Both the antibiotics are stable for at least 24 hours at 25 and 37°C, permitting storage at room temperature and pre-warming of PD bags to body temperature prior to its administration.

scholarly journals Application of Liquid Smoke from Coconut Shell in Tandipang (Dussumeiria Acutta) Smoked Fish To Extend Shelf Life

2020 ◽  
Vol 12 (2) ◽  
pp. 315
Author(s):  
Dyah Ayu Rakhmayeni ◽  
Tatty Yuniarti ◽  
Sukarno Sukarno
Keyword(s):  
Activation Energy ◽  
Shelf Life ◽  
Room Temperature ◽  
Plate Count ◽  
Fish Products ◽  
Smoked Fish ◽  
Liquid Smoke ◽  
Quality Degradation ◽  
Total Plate Count ◽  
Different Temperatures

Highlightaw on smoked tandipang fish analyzed.Peroxide value on smoked tandipang fish analyzed.TPC on smoked tandipang fish analyzed.The shelf life of liquid smoked tandipangfish stored at 27o C was obtained the value of t = 23.2 in units of weeks or 5.8 months of storage.AbstractFumigation using liquid smoke produces smoked fish products with a smoky flavor character and can increase shelf life. The research objective was to determine the shelf life of the tandipang fish which was processed using liquid smoking. The test was carried out by storing smoked fish in an incubator at different temperatures 30 °C, 40 °C, and 50 °C with three replications for 5 weeks (35 days). The samples prepared at each temperature were kept in an incubator for five weeks. The parameters tested for estimating shelf life are using the test data aW (activity water), peroxide number, and TPC (total plate count). The three parameters are selected by one parameter to calculate the shelf life of liquid smoked tandipang fish which is considered to greatly affect the quality degradation during storage. The aw parameter is used to determine the shelf life because it has a high R2 value with an activation energy of 86972.75 J / mol.K. Estimation of shelf life of liquid cured fish at room temperature using aw parameter is 23.2 weeks or 5.8 months.

scholarly journals Effect of Drying Processes on Stability of Anthocyanin Extracts from Saffron Petal

2014 ◽  
Vol 2 ◽  
pp. 13-18 ◽  
Author(s):  
Somayeh Heydari ◽  
Roya Rezaei ◽  
Gholam Hossein Haghayegh
Keyword(s):  
Room Temperature ◽  
Heating Temperature ◽  
Heating Time ◽  
Crocus Sativus ◽  
The Sun ◽  
Processing Treatment ◽  
Different Temperatures ◽  
The Stability ◽  
Synthetic Pigments ◽  
Good Substitute

Saffron (Crocus sativus) has cyanic color flowers with major colorant of anthocyanin. Attractive color and functional properties of anthocyanins make them a good substitute for synthetic pigments in the food industry. These natural soluble water colorants are rather unstable and influenced by final processing treatment. The drying process is critical to the stability of saffron petals anthocyanins. Four different dehydration methods were evaluated: traditional method (at room temperature and under the sun); dehydration with electrical oven at different temperatures; and dehydration with microwave at different powers. The results showed that the highest amount of anthocyanin was obtained when saffron petals treated by traditional methods (at room temperature and under the sun). According to the results, the stability of saffron petals anthocyanins gradually accessed with increase of the heating temperature and decrement of heating time until 100 °C. However, heated at 120 and 140 °C, the anthocyanins could break down, and their residual amounts declined within 20 min and 10 min, respectively. The results suggested that saffron petals anthocyanins tended to degrade at high temperatures (>100 °C). Between these methods, drying at room temperature and drying with microwave at 900 W obtained the highest and the lowest results respectively.

Streptokinase Stability Pattern during Storage in Various Solvents and at Different Temperatures

1975 ◽  
Vol 33 (03) ◽  
pp. 586-596 ◽  
Author(s):  
M Martin ◽  
Fräulein H Auel ◽  
Keyword(s):  
Room Temperature ◽  
Group Iii ◽  
Charged Colloids ◽  
Group I ◽  
Different Temperatures ◽  
Order Of Magnitude ◽  
Stability Pattern ◽  
The Stability ◽  
Incubation Temperatures ◽  
Dextran Solution

SummaryThe activity drop of 5 u streptokinase was measured in 1 ml each of various solutions (0.9% NaCl solution, 5% glucose solution, 5% levulose solution, 10% dextran solution, gelatin solution, 3% albumin solution, Michaelis buffer, glucose (5%)-heparin (750 u/ml) solution) at different incubation temperatures (–20° c, 4° c, 20 c, 37 C), and over different observation periods (15 min, 30 min, 45 min, 60 min, 6 h, 12 h, 24 h, and 48 h). Solution media tested for streptokinase-protecting quality were broken down into three groups.Group I: Solvents displaying excellent stabilizing properties (gelatin and albumin solutions).Group II: Solvents displaying medium stabilizing properties (dextran and levulose solutions).Group III: Solvents displaying poor stabilizing properties (NaCl and glucose solutions, Michaelis buffer).In testing streptokinase concentrations as used for therapeutic purposes (1500 u/ml, 50,000 u/ml), no decay was found to take place over observation periods of up to 48 h, and no influence by different solvents (Group I, II or III) was traceable. Heparin stored with streptokinase at room temperature over a period of 48 h did not alter the streptokinase stability.Some mechanisms concerning the stability pattern of streptokinase are discussed. It appears that low streptokinase concentrations need negatively charged colloids to keep the protein structure intact. The streptokinase-protecting macro-molecules tested so far were albumin, gelatin, and streptokinase. Obviously, streptokinase by itself was able to preserve its own stability provided its concentration was of a certain order of magnitude (1500 u/ml, 50,000 u/ml).

scholarly journals PHYSICAL STABILITY AND ANTIOXIDANT ACTIVITY ASSAY OF A NANOEMULSION GEL FORMULATION CONTAINING TOCOTRIENOL

2017 ◽  
Vol 9 ◽  
pp. 140
Author(s):  
Mentari Mayang Suminar ◽  
Mahdi Jufri
Keyword(s):  
Antioxidant Activity ◽  
Room Temperature ◽  
Inhibitory Concentration ◽  
Physical Stability ◽  
Tween 80 ◽  
Skin Damage ◽  
Activity Assay ◽  
Nanoemulsion Gel ◽  
Different Temperatures ◽  
The Stability

Objective: Tocotrienols have an antioxidant potential higher than that of tocopherols. Nanoemulsion gel can deliver tocotrienols into the skin toprevent skin damage caused by free radicals and improve the stability of the dosage form. The present study aimed to determine the physical stabilityand antioxidant activity of a nanoemulsion gel formulation containing tocotrienol.Methods: The tocotrienol nanoemulsion was made using tocotrienols, oleic acid, Tween 80, 96% ethanol, and propylene glycol. The gel base was madeusing a carbomer and triethanolamine. A physical stability test was conducted at three different temperatures, namely, low temperature (4±2°C),room temperature (27±2°C), and high temperature (40±2°C). The antioxidant activity was measured using the 2,2-diphenyl-1-picrylhydrazyl methodfor determining inhibitory concentration (IC50) values.Results: Formula 1 demonstrated the best physical stability, with a pH of 6.2. The droplet size of the tocotrienol nanoemulsion gel was 596 nm, witha zeta potential value of −27.1 nm. The IC50 of the tocotrienol nanoemulsion gel was 6252.14 ppm.Conclusion: The nanoemulsion gel formulation retained antioxidant activity and was physically stable for 8 weeks.

Stability Study of Epirubicin in Nacl 0.9% Injection

1997 ◽  
Vol 31 (9) ◽  
pp. 992-995 ◽  
Author(s):  
Montserrat Pujol ◽  
Montserrat Muñoz ◽  
Josefina Prat ◽  
Victoria Girona ◽  
Jordi De Bolós
Keyword(s):  
Shelf Life ◽  
Room Temperature ◽  
Degradation Kinetics ◽  
Storage Conditions ◽  
Hplc Method ◽  
Stability Study ◽  
Chemistry Laboratory ◽  
Maximum Decrease ◽  
Different Temperatures ◽  
The Stability

Objective To determine the stability of epirubicin in NaCl 0.9% injection under hospital storage conditions. Methods NaCl 0.9% solution was added to epirubicin iyophilized powder to make a final concentration of 1 mg/mL to study the degradation kinetics and 2 mg/mL to study the stability in polypropylene syringes under hospital conditions. Setting Physical chemistry laboratory, Unitat de Fisicoquímica, Universitat de Barcelona. Main outcome Measures Solutions of epirubicin at 2 mg/mL in NaCl 0.9% solutions stored in plastic syringes were studied under hospital conditions at room temperature (25 ± 1 °C) and under refrigeration (4 ± 1 °C) both protected from light and exposed to room light (~50 lumens/m2). All samples were studied in triplicate and epirubicin concentrations were obtained periodically throughout each storage/time condition via a specific stability-indicating HPLC method. To determine the degradation kinetics, solutions of epirubicin in NaCl 0.9% at 1 mg/mL were stored at different temperatures (40, 50, and 60 °C) to obtain the rate degradation constant and the shelf life at room temperature and under refrigeration. Results The degradation of epirubicin in NaCl 0.9% solutions follows first-order kinetics. The shelf life was defined as the time by which the epirubicin concentration had decreased by 10% from the initial concentration. In this study, epirubicin was stable in NaCl 0.9% injection stored in polypropylene containers for all time periods and all conditions. That results in a shelf life of at least 14 and 180 days at 25 and 4 °C, respectively. The maximum decrease in epirubicin concentration observed at 25 °C and 14 days was 4%, and at 4 °C and 180 days was 8%. The predicted shelf life obtained from the Arrhenius equation was 72.9 ± 0.2 and 3070 ± 15 days at 25 and 4 °C, respectively, in both dark and illuminated conditions. Conclusions Solutions of epirubicin in NaCl 0.9% at 2 mg/mL are chemically stable when they are stored in polypropylene syringes under hospital storage conditions. No special precaution is neccessary to protect epirubicin solutions (2 mg/mL) from light.

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