Solvolysis of some 1-(8α-ergolinyl)-3,3-diethylureas and their salts

1987 ◽  
Vol 52 (5) ◽  
pp. 1331-1339 ◽  
Author(s):  
Antonín Černý ◽  
Jan Beneš ◽  
Jaroslav Vachek ◽  
Milan Pešák ◽  
Josef Stuchlík ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Main Product ◽  
Ethanolic Solution ◽  
Decomposition Products ◽  
Solubility In Water ◽  
Long Term Storage ◽  
The Stability ◽  
Hydrolysis Of ◽  
Term Storage

Nine salts of 1-(8α-ergolinyl)-3,3-diethylurea (II) were prepared and their solubility in water and the stability of the aqueous solutions at 60 and 100 °C were studied. The main product of hydrolysis is 6-methyl-8α-aminoergoline IV. The urethan VII is formed in the ethanolic solution. Both decomposition products are also formed under long-term storage at +5 °C. The course of hydrolysis of N-propyl homologue III is similar. The decomposition of 9,10-didehydro derivative I is much slower under the conditions used.

Comparative Analysis of the Effect of Immersion of Porous Silicon in Aqueous Solutions of Li and Fe Salts on the Stability, Peak Position and Intensity of its Photoluminescence

2018 ◽  
Vol 386 ◽  
pp. 75-79
Author(s):  
Nikolay G. Galkin ◽  
Dmitrii Tkhyarbonovich Yan ◽  
Konstantin N. Galkin ◽  
Evgeniy Anatolievich Chusovitin ◽  
Mikhail Victorovich Bozhenko
Keyword(s):  
Porous Silicon ◽  
Aqueous Solutions ◽  
Blue Shift ◽  
Peak Position ◽  
Maximum Increase ◽  
Long Term Storage ◽  
Low Concentrations ◽  
The Stability ◽  
Term Storage

In the process of comparative studies of immersing layers of porous silicon (PS) in aqueous solutions of LiBr and Fe (NO3)3 with subsequent long-term storage up to 150 days, it is established that there exists: (1) the range of concentrations of LiBr (S/2 - S/4) and Fe (NO3)3 (0.2 M), which provide the maximum increase in the intensity of PL; (2) at low concentrations of both salts, a blue shift of the PL peaks and an increase in their intensity are observed during the long-term storage, which is associated with a decrease in the size of the NC in the PS and the influence of silicon bonds with lithium or iron ions; (3) full protection of the PS layer is observed in case of immersion in Fe (NO3)3 with a concentration of 0.7M - 0.8M.

Stability and epimerisation behaviour of ergot alkaloids in various solvents

2008 ◽  
Vol 1 (1) ◽  
pp. 67-78 ◽  
Author(s):  
M. Hafner ◽  
M. Sulyok ◽  
R. Schuhmacher ◽  
C. Crews ◽  
R. Krska
Keyword(s):  
Degradation Products ◽  
Ergot Alkaloids ◽  
Carbonate Buffer ◽  
Long Term Storage ◽  
No Formation ◽  
Temperature Levels ◽  
The Stability ◽  
Extraction Mixture ◽  
Term Storage

In this paper the stability and degree of epimerisation of six major ergot alkaloids at three different temperature levels (-20 °C, +4 °C and +20 °C) over periods of 18 hours and six weeks is reported for the first time. The behaviour of ergometrine, ergocornine, ergocristine, α-ergocryptine, ergosine and ergotamine was thoroughly studied in seven solvents which are employed for the preparation of calibrants and extraction mixtures, respectively. Moreover, the stability of the ergot alkaloids was tested in different cereal extracts (rye, wheat, barley, oats) for 1, 2 and 6 days. Of the toxins tested, the ergopeptide-type toxins ergosine, ergotamine, ergocornine, α-ergocryptine and ergocristine showed similar behaviour patterns. The simple lysergic acid derivative ergometrine was more stable and showed hardly any epimerisation to ergometrinine, with the sum of both epimers remaining constant in all seven solvents. The ergopeptides tested show variable epimerisation tendencies, and were also less stable during six weeks at 20 °C. Ergosine showed the highest degree of epimerisation (43% after 6 weeks at 20 °C). In general, the order of epimerisation promotion was methanol/dichloromethane > acetonitrile/buffer > extraction mix > stabilising solution > acetonitrile >> chloroform. Long-term storage at room temperature can only be carried out in chloroform, which showed no epimerisation for all toxins even at 20 °C and also kept the sum of R and S forms constant, which indicates no formation of aci-epimers or other degradation products. Long-term storage of ergot alkaloids in acetonitrile, the most convenient solvent with respect to HPLC analysis, should be carried out at temperatures of -20 °C or below. The constant epimer ratio of all ergot alkaloids in the extraction mixture acetonitrile/ammonium carbonate buffer (200 mg/l; 92:8, v/v) during an HPLC run (18 hours) demonstrates the stability of the toxins in this extraction mixture.

The Carbonate-Hardening Lime Construction Material Properties Formation during their Long-Term Storage and Use under Normal Conditions

2019 ◽  
Vol 974 ◽  
pp. 187-194 ◽  
Author(s):  
Nikolay V. Lyubomirskiy ◽  
Tamara A. Bakhtina ◽  
Alexander S. Bakhtin ◽  
Sergey I. Fedorkin
Keyword(s):  
Construction Material ◽  
Construction Materials ◽  
Materials Properties ◽  
Long Term Storage ◽  
Efficiency Assessment ◽  
The Stability ◽  
Term Storage ◽  
Long Storage ◽  
Quality Construction

This paper presents the lime binding forced carbonate-hardening materials properties formation study and determins the stability of these properties during long-term storage and use under normal conditions. The tests showed these materials stability properties over time, confirming the strength and density growth of the test samples after long storage due to the calcium hydroxide recrystallization completion into calcium carbonate processes. Also, the results of the samples carbonate hardening study under natural conditions during 18 months are presented. An efficiency assessment of forced carbonate hardening as one of the methods of recycling technogenic CO2 in order to reduce its emissions in the atmosphere, and, in the result, to obtain high-quality construction materials has been made.

Synthesis Optimization of Guanidinium Dinitramide (GDN)

2020 ◽  
Vol 20 (11) ◽  
pp. 6855-6861
Author(s):  
Wooram Kim ◽  
Mijeong Park ◽  
Jong-Ki Jeon ◽  
Youngmin Jo
Keyword(s):  
Maximum Yield ◽  
Resonance Structure ◽  
Kcal Mole ◽  
Additional Advantage ◽  
Long Term Storage ◽  
Ft Ir ◽  
The Stability ◽  
Infrared Frequencies ◽  
Term Storage

Dinitramide anion [−N(NO2)2] salt composed of resonance structure is a plausible oxidizing agents, as efficient propellant. Among them, guanidinium dinitramide (GDN) is an organic compound improving the stability against moisture, as well long term storage. An additional advantage composed guanidinium ion is the reaction efficient via the decomposed by-product during pyrognostics, maximum yield of 99%. The types of GDN (GDN-I, II, III, IV, V) were synthesized using several starting material such as guanidine acetate, chloride, carbonate, nitrate and sulfate under hydrodeprivation. In this work, the intermediates formed in these processes were closely identified and their thermal properties, and chemical structure were examined. The absorption peaks by Fourier transform infrared (FT-IR) were found guanidinium infrared frequencies (3452, 3402, 3354, 3278, 1642 cm−1) and dinitramide infrared frequencies (3208, 1570, 1492, 1416, 1337, 1179, 1000 cm−1). The activation energy of GDN samples were obtained Ea = 53.26 Kcal/mole (GDN-I), 50.94 Kcal/mole (GDN-II), 52.34 Kcal/mole (GDN-III), 62.19 Kcal/mole (GDN-IV), 55.32 Kcal/mole (GDN-V) from exothermic at over 153°C.

scholarly journals Stability of Folate and Vitamin B12in Human Serum after Long-Term Storage: A Follow-Up after 13 Years

2018 ◽  
Vol 2018 ◽  
pp. 1-4 ◽  
Author(s):  
Eugène H. J. M. Jansen ◽  
Piet K. Beekhof
Keyword(s):  
Human Serum ◽  
Storage Time ◽  
Vitamin B ◽  
Serum Samples ◽  
Long Term Storage ◽  
Nutrition Research ◽  
The Stability ◽  
Term Storage

In epidemiological and nutrition research, it is very important to evaluate the stability of biomarkers as function of both storage time and temperature. In this study, the stability of folate and vitamin B12in human serum samples has been tested after long-term storage at −80°C up to 13 years. Serum samples of 16 individuals were used in this study. The concentration of folate and vitamin B12has been determined att=0and at 1, 8, and 13 years after storage at −80°C. The folate concentrations in serum samples remained stable at −80°C. The concentration of vitamin B12was decreasing during the time of the study to about 50%. The correlation of the folate and also of the vitamin B12concentrations in the stored samples compared with the starting values was still good. Therefore, although the concentration of vitamin B12decreased upon storage, reliable comparative analyses can still be performed.

scholarly journals Influence of processing factors on the stability of model mayonnaise with whole egg during long-term storage

2017 ◽  
Vol 81 (4) ◽  
pp. 803-811 ◽  
Author(s):  
Masahiro Ariizumi ◽  
Megumi Kubo ◽  
Akihiro Handa ◽  
Takashi Hayakawa ◽  
Kentaro Matsumiya ◽  
...  
Keyword(s):  
Long Term Storage ◽  
The Stability ◽  
Processing Factors ◽  
Whole Egg ◽  
Term Storage

scholarly journals Changes of salivary biomarkers under different storage conditions: effects of temperature and length of storage

2018 ◽  
Vol 29 (1) ◽  
pp. 94-111 ◽  
Author(s):  
Tomás Barranco ◽  
Asta Tvarijonaviciute ◽  
Damián Escribano ◽  
Fernando Tecles ◽  
José J Cerón ◽  
...  
Keyword(s):  
Antioxidant Capacity ◽  
Room Temperature ◽  
Storage Conditions ◽  
Trolox Equivalent Antioxidant Capacity ◽  
Long Term Storage ◽  
Reducing Ability ◽  
Trolox Equivalent ◽  
The Stability ◽  
Term Storage

Introduction: In this report, we aimed to examine the stability of various analytes in saliva under different storage conditions. Materials and methods: Alpha-amylase (AMY), cholinesterase (CHE), lipase (Lip), total esterase (TEA), creatine kinase (CK), aspartate aminotransferase (AST), lactate dehydrogenase (LD), lactate (Lact), adenosine deaminase (ADA), Trolox equivalent antioxidant capacity (TEAC), ferric reducing ability (FRAS), cupric reducing antioxidant capacity (CUPRAC), uric acid (UA), catalase (CAT), advanced oxidation protein products (AOPP) and hydrogen peroxide (H2O2) were colorimetrically measured in saliva obtained by passive drool from 12 healthy voluntary donors at baseline and after 3, 6, 24, 72 hours, 7 and 14 days at room temperature (RT) and 4 ºC, and after 14 days, 1, 3 and 6 months at – 20 ºC and – 80 ºC. Results: At RT, changes appeared at 6 hours for TEA and H2O2; 24 hours for Lip, CK, ADA and CUPRAC; and 72 hours for LD, Lact, FRAS, UA and AOPP. At 4 ºC changes were observed after 6 hours for TEA and H2O2; 24 hours for Lip and CUPRAC; 72 hours for CK; and 7 days for LD, FRAS and UA. At – 20 ºC changes appeared after 14 days for AST, Lip, CK and LD; and 3 months for TEA and H2O2. At – 80 ºC observed changes were after 3 months for TEA and H2O2. Conclusions: In short-term storage, the analytes were more stable at 4 ºC than at room temperature, whereas in long-term storage they were more stable at - 80 ºC than at – 20 ºC.

scholarly journals Evaluation of the Stability of Bacteriophages in Different Solutions Suitable for the Production of Magistral Preparations in Belgium

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 865
Author(s):  
Hans Duyvejonck ◽  
Maya Merabishvili ◽  
Mario Vaneechoutte ◽  
Steven de Soir ◽  
Rosanna Wright ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Therapeutic Dose ◽  
Bacterial Species ◽  
The Other ◽  
Manufacturing Processes ◽  
High Importance ◽  
Long Term Storage ◽  
The Stability ◽  
Term Storage

In Belgium, the incorporation of phages into magistral preparations for human application has been permitted since 2018. The stability of such preparations is of high importance to guarantee quality and efficacy throughout treatments. We evaluated the ability to preserve infectivity of four different phages active against three different bacterial species in five different buffer and infusion solutions commonly used in medicine and biotechnological manufacturing processes, at two different concentrations (9 and 7 log pfu/mL), stored at 4 °C. DPBS without Ca2+ and Mg2+ was found to be the best option, compared to the other solutions. Suspensions with phage concentrations of 7 log pfu/mL were unsuited as their activity dropped below the effective therapeutic dose (6–9 log pfu/mL), even after one week of storage at 4 °C. Strong variability between phages was observed, with Acinetobacter baumannii phage Acibel004 being stable in four out of five different solutions. We also studied the long term storage of lyophilized staphylococcal phage ISP, and found that the titer could be preserved during a period of almost 8 years when sucrose and trehalose were used as stabilizers. After rehydration of the lyophilized ISP phage in saline, the phage solutions remained stable at 4 °C during a period of 126 days.

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