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Critical physicochemical properties of lubricating oils for aviation applications and their significance in terms of flight safety

Abstract

The article presents the role of lubricating oils for aviation applications, along with their classification, and discusses the key physicochemical properties. It characterises engine, transmission gear, hydraulic and instrumentation oils and their impact on a device operational reliability. It also points out the requirements for these products in relation to the operating conditions and the chemical composition of a product.

Open access
Modelling of absorption, distribution and physicochemical properties of AT1 receptor antagonists / Modelovanie absorpcie, distribúcie a fyzikálnochemických vlastnosti antagonistov AT1 receptorov

Abstract

The theoretical chemistry methods were used to elucidate absorption, distribution and physicochemical properties of AT1 receptor antagonists and dual angiotensin II and endothelin A receptor antagonist (PS-433540). Computed partition coefficients (ALOGPS method) studied for drugs varied between 2.98 and 6.66. Neutral compounds are described as lipophilic drugs. Telmisartan is a drug with the highest lipophilicity. The neutral forms of the studied AT1 receptor antagonists are practically insoluble in water, and their computed solubilities is in interval between 2.04 and 22.65 mg/l (ALOGpS method). The calculated pKa values for tetrazolyle moiety are in the range 3.92-5.00 and for carboxylic moiety 3.12-5.50. Telmisartan (polar surface area = 72.95 A) and irbesartan (polar surface area = 87.14 A) belong to the AT1 receptor antagonists with increased absorption.

Open access
Synthesis and structure-physicochemical properties relationship of thiophene-substituted bis(5,4-d)thiazoles

Abstract

Substituted thiophene-2-carbaldehydes 1a-dwere utilized in the synthesis of symmetrically substituted thiazolo[5,4-d]thiazoles 3a-d. Bis(5,4-d)thiazoles with thiophene core at the termini are the most employed in the chemistry of materials but exhibit insufficient solubility in majority of organic solvents with notable impact on the low yields of products. Accordingly, the synthetic approach towards 2,5-dithiophen- 2-yl-thiazolo[5,4-d]thiazole (3a) and its substituted derivatives 3b-d is discussed under the various reaction conditions. Appropriate structural characterisations are included with emphasis on relationship between structure and physicochemical properties highlighting the UV-Vis and fluorescence.

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Fortification of milk with phytosterol and its effect on sensory and physicochemical properties

increases ( Phillips et al ., 1995 ). Therefore, the added fat from the emulsion might also have had an effect on the viscosity of the fortified milk. The viscosity of the fortified milk, however, was within the range generally observed for milk. Table 3 Physicochemical properties of phytosterol-enriched milk Parameters Control Phytosterol-enriched milk Fortified milk containing B emulsion formulation. cP = centipoises; s.d. = standard deviation. pH 6.67 ± 0.02 a 6.57 ± 0.01 b Acidity (% of lactic acid) 0.15 ± 0.005 a 0.17 ± 0

Open access
Hydrazinyldiene-chroman-2,4-diones in inducing growth arrest and apoptosis in breast cancer cells: Synergism with doxorubicin and correlation with physicochemical properties

Abstract

This study evaluates the effects of previously synthesized hydrazinyldiene-chroman-2,4-diones on cell proliferation and apoptosis, cell cycle distribution and migration capacity of MCF-7 breast cancer cells in synergy with doxorubicin. Physicochemical properties of the synthesized compounds were correlated with their structure and activity. Significant cell viability decrease in comparison with the effect of doxorubicin alone and the reference 4-hydroxycoumarin was observed when combination treatment comprising doxorubicin and the title compounds was applied. Synergistic effect with doxorubicin was also observed in down-regulation of phospho-Thr308Akt levels, confirming reduced proliferation and increased apoptosis. Combined treatment increased the percentage of cells arrested at the G2/M stage. Additive inhibition of cell migration was also observed, pointing to the possibility of reducing the risk of metastases. With their solubility profile and log D7.4, all the synthesized compounds follow Lipinski’s rule of five for good permeability (absorption) potential.

Open access
The Role of Habitat Types and Soil Physicochemical Properties in the Spread of a Non Native Shrub Lantana Camara in the Doon Valley, Western Himalaya, India

Abstract

Invasive alien species colonize very aggressively and forcefully, menacing native biodiversity. The success of invasive alien plants is due to their opportunistic exploitation of anthropogenic disturbances, the absence of natural enemies, free from herbivory and frequently their allelopathic competition. Invasive species can have a significant impact on development, affecting sustainability of livelihood, food security and essential ecosystem services and dynamics. Lantana camara is a documented weed of worldwide significance; it is indigestible due to its toxic chemicals and highly competitive. In this study physicochemical properties of soil were analysed from different high and low Lantana infested areas. Significant site effect was frequently observed than effect due to invasion status. The present study tested the impact of soil properties in the measured and calculated attributes of Lantana by randomly sampling soil from the highly invaded and less invaded sites in different habitats using the Modified Whittaker plot design. Results indicated that edaphic factors such as soil pH, total nitrogen, soil organic carbon, phosphorus and potassium content positively influenced the growth of Lantana and helped in its own further invasion process. These factors were also positively influencing the measured and calculated attributes of Lantana such as canopy coverage, average crown diameter, shrub canopy area, phytovolume and biomass from all sites. However some attributes like shrub height and stem diameter were negatively influenced by these soil factors. The present results show that Lantana invasion can significantly improve the soil nutrient level but also positively increasing the chances of its further invasion with more copious plant attributes.

Open access
Physicochemical and Microbiological Characteristics of Some Samples of Honey Produced by Beekeepers In Algeria

de l’agriculture et de la biologie, 2005, no. 12, pp. 773-776. NEVAS, M. - HIELM, S. - LINDSTOM, M. - HOM, H. - KOIVULEHTO, K. - KORKEALA, H. 2005. High prevalence of Clostridium botulinum types A and B in honey samples detected by polymerase chain reaction. In Miocrobiologia, vol. 11, 2005, no. 3, pp. 343-350. OMAFUVBE, B.O. - AKANBI, O. 2009. Microbiological and physicochemical properties of some commercial Nigerian honey. In African Journal of Microbiology Research, vol. 3, 2009, no. 12, pp. 891-896. OUCHEMOUKH, S

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Process Optimization for Dietary Fiber Production from Cassava Pulp Using Acid Treatment

. 5. Artati, E.K. & Andik, P.A. (2006). Effect of acid concentration on starch hydrolysis of banana. Ekuilibrium . 5(1), 8-12. 6. Atichokudomchai, N., Shobsngob, S., Chinachoti, P. & Varavinit, S. (2001). A study of some physicochemical properties of high-crystalline tapioca starch. Starch/Stärke . 53, 577-581. 7. Caprez, A., Arrigoni, E., Amado, R. & Neukom, H. (1986). Influence of different types of thermal treatment on the chemical composition and physical properties of wheat bran. Journal of Cereal Science . 4, 233-239. DOI: 10.1016/S0733

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Correlation of domination parameters with physicochemical properties of octane isomers

polarity [ 14 ]. In a comprehensive study of numerous properties of octane isomers, Randić et. al [ 10 , 12 , 14 ] have used single molecular descriptors and concluded that different physicochemical properties depend on different descriptors. So far in the literature of chemical graph theory, domination parameters have not been used to predict the physical properties of chemical compounds. Therefore, in the present study an attempt has been made to study physical properties of octane isomers by using domination parameters. The values of γ c , γ t and γ t

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Physicochemical properties, kinetics and thermodynamic studies of polyphenol oxidase from sorghum (Sorghum bicolor (L.) Moench) for potential use in industry

Abstract

Advances Polyphenol Oxidase (PPO) from Sorghum bicolor (white and yellow varieties) grains were investigated for optimum processing condition. The partially purified enzyme was obtained from two varieties of Sorghum bicolor by step-wise separation through ion-exchange and size-exclusion chromatography. The final purification gave a yield of 7.33 % and 12.3 % for PPO from white and yellow sorghum respectively. The PPO has Vmax and Km of 2.66 U.mL−1 and 19.72 mM for white sorghum, 1.33 U.mL−1 and 12.92 mM for yellow sorghum. The optimal pH of PPO activity was found at pH 4 and pH 7 for white and pH 4 and pH 8 for yellow sorghum. The pKa 7.4 and 8.7 were obtained for PPO from white sorghum, and pKa 5.4, 7.4 and 8.5 for yellow sorghum. The PPO residual activity were above 70 % at 5 hours of incubation within the neutral pH ranges for white sorghum, while those of yellow sorghum were below 40 %. The optimum temperature of 40 ºC and 30 ºC for white and yellow sorghum PPO respectively. The average value of enthalpy (ΔH), entropy (ΔS) and Gibbs free energy (ΔG) obtained at 20 min of incubation and temperature 50 – 80 °C were respectively 49.03 kJ.mol−1, - 129.52 J.mol−1.K−1, and 92.81 kJ.mol−1 for white sorghum PPO, and 90.1 kJ.mol−1, - 9.29 J.mol−1.K−1, and 93.37 kJ.mol−1 for yellow sorghum PPO. Zn2+, Fe2+ and ascorbic acid inhibited PPO while Cu2+, Na+ and K+ activated the enzyme. The results suggest the processing parameters for controlling PPO in potential industrial application of white and yellow sorghum grains.

Open access