Examination of growth of probiotic microbes by an isoperibolic calorimetrySchäffer, B.; Keller, B.; Daróczi, L.; Lőrinczy, Dénes
doi: 10.1007/s10973-010-0932-4pmid: N/A
Due to the increasing consumers’ interest in up-to-date nutrition nowadays the production of main part of fermented dairy products (e.g. yogurt, kefir) is made by using probiotic microbes. The majority of this product group are the flavoured variations, the sweetener of which is, first of all, still refined sugar (e.g. saccharose). Honey of natural origin, consequently preferred from the nutritional physiological point of view, is suitable to replace this refined carbohydrate. In our experiments we have sweetened the most frequently used milk containing of 1.6 and 3.6% fat with generally used saccharose of 10%, and the difference in the dry material content was equilibrated by drink water of 3% (control product). The experimental product was sweetened with robinia honey of 13% (dry material content was 77%). The fermentation was performed with a probiotic culture of 5%, which was clinically tested to be probiotic. The fermentation process was conducted in isotherm regime at 36 °C during 18 h in batch wessels using SETARAM Micro DSC II calorimeter. The calorimetric enthalpy was proportional to the probiotic microbe counts generated during the fermentation. Due to our experiments, we have come to the conclusion that honey instead of hindering much rather stimulates the growth of probiotic microbes. At sample pairs sweetened by saccharose and acacia honey, respectively, the higher enthalpy was measured at samples containing honey in all cases.
A study of thermal–mechanical properties of an automotive coating exposed to natural and simulated bird droppingsRamezanzadeh, B.; Mohseni, M.; Yari, H.; Sabbaghian, S.
doi: 10.1007/s10973-009-0442-4pmid: N/A
Biological resistance of coatings can be regarded as one of the main properties in automotive industries. This study aims to investigate the effects of biological materials on the mechanical performance of an automotive clear coat. To this end, two acrylic melamine clear coats containing different melamine cross-linker contents were used. In addition, biological resistance of these clear coats were studied at two different ageing processes including pre-ageing and post-ageing which involve various hot-cold, humid shockings and UV radiation of sunlight. By the aid of optical microscopy, micro Vickers and DMTA analyses, different optical and mechanical properties such as micro hardness, T g , cross-linking density and storage modulus were studied. Results revealed an inverse impact of both biological materials to decrease the clear coats mechanical attributes. In addition, a complicated effect of ageing conditions was observed for both clear coats exposed to these materials. It was shown that the coating having a higher mechanical properties and T g even resulted in a lower biological resistance.
Thermal decomposition behavior of potassium and sodium jarosite synthesized in the presence of methylamine and alanineKotler, J.; Hinman, Nancy; Richardson, C.; Scott, Jill
doi: 10.1007/s10973-009-0338-3pmid: N/A
Biomolecules, methylamine and alanine, found associated with natural jarosite samples peaked the interest of astrobiologists and planetary geologists. How the biomolecules are associated with jarosite remains unclear although the mechanism could be important for detecting biosignatures in the rock record on Earth and other planets. A series of thermal gravimetric experiments using synthetic K-jarosite and Na-jarosite were conducted to determine if thermal analysis could differentiate physical mixtures of alanine and methylamine with jarosite from samples where the methylamine or alanine was incorporated into the synthesis procedure. Physical mixtures and synthetic experiments with methylamine and alanine could be differentiated from one another and from the standards by thermal analysis for both the K-jarosite and Na-jarosite end-member suites. Changes included shifts in on-set temperatures, total temperature changes from on-set to final, and the presence of indicator peaks for methylamine and alanine in the physical mixture experiments.
Calorimetric studies of interactions of some peptides with electrolytes, urea and ethanol in water at 298.15 KPiekarski, Henryk; Nowicka, Bożenna
doi: 10.1007/s10973-009-0547-9pmid: N/A
The standard molar enthalpies of solution at infinite dilution of glycylglycine, dl -alanyl- dl -alanine and glycylglycylglycine in aqueous solutions of potassium chloride and ethanol as well as of glycylglycine and glycylglycylglycine in the solutions containing urea and water have been determined by calorimetry at the temperature 298.15 K. Changes of solution enthalpy, expressed in a form so-called heterotactic interaction coefficients, were used for analysis of interactions occurring between the investigated solutes in water. The group contributions illustrating the interactions of KCl, urea and ethanol with selected functional groups in the peptide molecules, namely CH 2 , “pep,” and “ion” groups, were calculated and discussed.
Heat-treated biodegradable films and foils of collagen hydrolysate crosslinked with dialdehyde starchLangmaier, F.; Mokrejs, P.; Mladek, M.
doi: 10.1007/s10973-009-0525-2pmid: N/A
Gels of collagen hydrolysate (H) crosslinked with dialdehyde starch (DAS) are marked by a strong tendency to aging, which means a certain problem during their processing into biodegradable packaging materials. Applying casting technology and drying these materials by heating air-dry films and foils for a limited time (1–4 h) at 105 °C may eliminate the aging problem. Solubility of heat-treated films in an aqueous environment remains preserved, but depending on how long this temperature acts and on the DAS content in the film, time of film disintegration prolongs from 1–1.5 h to 1300 h (≈54 days). It is probably caused by the functional groups initially blocked by sorbed water, which get released to produce hydrogen inter-chain crosslinks. The decrease in glass transition temperature ( T g ) of such films varies with content of water sorbed in films in an interval of 90.2–189 °C.
Effect of wool keratin proteins and peptides on hair water sorption kineticsBarba, C.; Martí, M.; Roddick-Lanzilotta, A.; Manich, A.; Carilla, J.; Parra, J.; Coderch, L.
doi: 10.1007/s10973-010-0691-2pmid: N/A
Most beauty care products and treatments primarily affect the cuticle layers of hair fibers. The resulting damage has an adverse effect on hair water absorption. Water changes a wide variety of properties of human hair and is therefore of fundamental interest. Wool proteins are mild, natural, biodegradable, and sustainably produced with multiple functionalities and potential for use in the personal care and detergent market. In this study, the effect on hair water sorption of two types of keratin samples obtained from wool is investigated. Modifications of hair water sorption due to a bleaching treatment have been demonstrated, with lower values of water sorption capacity and an increase of the fibers permeability. Applications of keratin peptides and proteins to bleached hair improved the water sorption properties of the fibers and reduced their permeability.
Anti-fungal effect of berberine on Candida albicans by microcalorimetry with correspondence analysisZhao, Yanling; Yan, Dan; Wang, Jiabo; Zhang, Ping; Xiao, Xiaohe
doi: 10.1007/s10973-009-0565-7pmid: N/A
Using a LKB-2277 bioactivity monitor, stop-flow mode, the power–time curves of Candida albicans growth at 37 °C affected by berberine were measured. The check experiments were studied based on agar cup method to observe the inhibitory diameter and serial dilution method to determine the minimal inhibitory concentration (MIC) of berberine on C. albicans growth. By analyzing the quantitative thermogenic parameters taken from the power–time curves using correspondence analysis (CA), we could find that berberine at a low concentration (5.0 μg mL −1 ) began to inhibit the growth of C. albicans and at a high concentration (75.0 μg mL −1 ) completely inhibited C. albicans growth. The anti-fungal activity of berberine could also be expressed as half-inhibitory concentration IC 50 , i.e., 50% effective in this inhibition. The value of IC 50 of berberine on C. albicans was 34.52 μg mL −1 . The inhibitory diameters all exceeded 10 mm in test range and the MIC was 500 μg mL −1 . Berberine had strong anti-fungal effect on C. albicans growth. This work provided an important idea of the combination of microcalorimetry and CA for the study on anti-fungal effect of berberine and other compounds. Compared with the agar cup method and serial dilution method, microcalorimetry not only offered a useful way for evaluating the bioactivity of drugs, but also provides more information about the microbial growth and all this information was significant for the synthesis and searching of antibiotics.
Thermodynamics of citrate complexation with Mn 2+ , Co 2+ , Ni 2+ and Zn 2+ ionsWyrzykowski, D.; Chmurzyński, L.
doi: 10.1007/s10973-009-0523-4pmid: N/A
Isothermal titration calorimetry has been used to determine the stoichiometry, formation constants and thermodynamic parameters (Δ G o , Δ H , Δ S ) for the formation of the citrate complexes with the Mn 2+ , Co 2+ , Ni 2+ and Zn 2+ ions. The measurements were run in Cacodylate, Pipes and Mes buffer solutions with a pH of 6, at 298.15 K. A constant ionic strength of 100 mM was maintained with NaClO 4 . The influence of a metal ion on its interaction energy with the citrate ions and the stability of the resulting complexes have been discussed.