Search results for "Calorimetry"
showing 10 items of 504 documents
Dielectric, thermal and Raman spectroscopy studies of lead-free (Na0.5Bi0.5)1−xSrxTiO3 (x = 0, 0.04 and 0.06) ceramics
2016
ABSTRACTLead-free (Na0.5Bi0.5)1−xSrxTiO3 (x = 0, 0.04 and 0.06) ceramics with relative densities above 97% were prepared by solid-state synthesis process. Their dielectric, thermal and Raman properties were studied. X-ray diffraction analysis shows perovskite structure with rhombohedral symmetry at room temperature. Sr doping of Na0.5Bi0.5TiO3 (NBT) results in an increase of the dielectric permittivity, diffusing of the permittivity maximum and its shift toward lower temperatures. The temperature of the rhombohedral–tetragonal phase transition indicated by the differential scanning calorimetry (DSC) peak and relaxational dielectric anomaly near the depolarization temperature are also shifte…
Communication versus waterproofing: the physics of insect cuticular hydrocarbons
2019
Understanding the evolution of complex traits is among the major challenges in biology. One such trait is the cuticular hydrocarbon (CHC) layer in insects. It protects against desiccation and provides communication signals, especially in social insects. CHC composition is highly diverse within and across species. To understand the adaptive value of this chemical diversity, we must understand how it affects biological functionality. So far, CHCs received ample research attention, but their physical properties were little studied. We argue that these properties determine their biological functionality, and are vital to understand how CHC composition affects their adaptive value. We investigat…
Collisional mechanism of ligand release by Bombyx mori JHBP, a member of the TULIP / Takeout family of lipid transporters.
2020
International audience; Juvenile hormones (JHs) regulate important processes in insects, such as postembryonic development and reproduction. In the hemolymph of Lepidoptera, these lipophilic sesquiterpenic hormones are transported from their site of synthesis to target tissues by high affinity carriers, the juvenile hormone binding proteins (JHBPs). Lepidopteran JHBPs belong to a recently uncovered, yet very ancient family of proteins sharing a common lipid fold (TULIP domain) and involved in shuttling various lipid ligands. One important, but poorly understood aspect of JHs action, is the mechanism of hormone transfer to or through the plasma membranes of target cells. Since many membrane-…
Spray-Drying Performance and Thermal Stability of L-Ascorbic Acid Microencapsulated with Sodium Alginate and Gum Arabic
2019
[EN] The potential of sodium alginate (ALG) and gum arabic (GA) as wall polymers for Lascorbic acid (AA) encapsulation as a tool for their preservation against the thermo-oxidative degradation was investigated. The influence of such polymers used as wall material on the AAcontent, size, encapsulation efficiency, encapsulation yield and thermo-oxidative stability were evaluated. The AA-microparticles were obtained using the spray-drying technique. An experimental Taguchi design was employed to assess the influence of the variables in the encapsulation process. The microparticles morphology and size distribution were characterized by scanning electron microscopy and laser diffraction. The the…
Adsorption equilibria of water vapor on cork.
2010
International audience; We report here for the first time a complete thermodynamic study of water vapor adsorption on crude cork powder and plate. Adsorption−desorption isotherms were accurately measured by thermogravimetry at 283, 298, and 313 K in a large range of relative pressure. Adsorption enthalpies were determined by calorimetry as a function of loading. Adsorption−desorption isotherms exhibit a hysteresis due to the swelling of the material. The influence of the presence of lenticels on the adsorption properties of cork is found to be negligible. A detailed analysis and interpretation of adsorption data allow proposal of an adsorption mechanism in two steps. (i) First, water adsorb…
Resting Energy Expenditure and Substrate Oxidation in Malnourished Patients With Type 1 Glycogenosis.
2019
Abstract Context Type 1a and 1b glycogenosis [glycogen storage disorder (GSD)1a, GSD1b] are rare diseases generally associated with malnutrition. Although abnormal substrate oxidation rates and elevated energy expenditures might contribute to malnutrition, this issue has not been investigated. Objective To investigate whether abnormal resting energy expenditure (REE) and substrate oxidation rate characterize patients with GSD1. Design Cross-sectional study Setting Outpatient referral center for rare diseases and laboratory of clinical nutrition at the University Hospital of Palermo Patients Five consecutive patients with GSD1 (4 type a, 1 type b; 3 men, 2 women; age range, 19 to 49 years) M…
Specific and highly efficient condensation of GC and IC DNA by polyaza pyridinophane derivatives
2018
Abstract Two bis-polyaza pyridinophane derivatives and their monomeric reference compounds revealed strong interactions with ds-DNA and RNA. The bis-derivatives show a specific condensation of GC- and IC-DNA, which is almost two orders of magnitude more efficient than the well-known condensation agent spermine. The type of condensed DNA was identified as ψ-DNA, characterized by the exceptionally strong CD signals. At variance to the almost silent AT(U) polynucleotides, these strong CD signals allow the determination of GC-condensates at nanomolar nucleobase concentrations. Detailed thermodynamic characterisation by ITC reveals significant differences between the DNA binding of the bis-deriv…
Effect of lemon leaves on energy and C–N balances, methane emission, and milk performance in Murciano-Granadina dairy goats
2018
[EN] The objective of this experiment was to find out the effect of lemon leaves on energy and C-N balances, methane emission, and milk performance in dairy goats. Lemon leaves were used to replace alfalfa as forage in a diet for Murciano-Granadina goats. Ten Murciano-Granadina dairy goats (44.1 +/- 4.47 kg of BW) in late lactation (185 +/- 7.2 d) were selected in a crossover design experiment, where each goat received 2 treatments in 2 periods. One group was fed a mixed ration with 450 g of pelleted alfalfa per kilogram of DM (ALF diet) and, the other group replaced alfalfa with 450 g of pelleted lemon leaves per kilogram DM (LEM diet). The concentrate was pelleted, being the same for the …
Analysis of substrate binding in individual active sites of bifunctional human ATIC
2018
Aminoimidazolecarboxamide ribonucleotide formyl transferase (AICARFT): Inosine monophosphate cyclohydrolase (IMPCH, collectively called ATIC) is a bifunctional enzyme that catalyses the penultimate and final steps in the purine de novo biosynthesis pathway. The bifunctional protein is dimeric and each monomer contains two different active sites both of which are capable of binding nucleotide substrates, this means to a potential total of four distinct binding events might be observed. Within this work we used a combination of site-directed and truncation mutants of ATIC to independently investigate the binding at these two sites using calorimetry. A single S10W mutation is sufficient to blo…
Amyloid β-peptide insertion in liposomes containing GM1-cholesterol domains.
2015
Neuronal membrane damage is related to the early impairments appearing in Alzheimer's disease due to the interaction of the amyloid β-peptide (Aβ) with the phospholipid bilayer. In particular, the ganglioside GM1, present with cholesterol in lipid rafts, seems to be able to initiate Aβ aggregation on membrane. We studied the thermodynamic and structural effects of the presence of GM1 on the interaction between Aβ and liposomes, a good membrane model system. Isothermal Titration Calorimetry highlighted the importance of the presence of GM1 in recruiting monomeric Aβ toward the lipid bilayer. Light and Small Angle X-ray Scattering revealed a different pattern for GM1 containing liposomes, bot…