4 research outputs found
Jak budowa molekularna i warunki termodynamiczne (p-T) wpływają na dynamikę molekularną monoalkoholi oraz dioli?
Alcohols are studied from the beginning of the twentieth century in
order to find answers to many fundamental questions related to the specific
properties of materials containing hydrogen bonds. The unique properties
of these compounds is not only the ability to easily supercooling to a glassy
state, but above all the fact that in some of them (with single OH group in
the structure), the dynamics of the hydrogen bonds can be monitored
directly with a broadband dielectric spectroscopy (BDS) in a very wide
range of times, from 10-9s to 103s. Therefore, studies on molecular
dynamics of monoalcohols are essential for understanding the properties of
associative materials. In the case of polyols (diols have in the structure two
OH groups) we do not directly observe the relaxation process responsible
for the occurrence of supramolecular structures, however, their research
provides a lot of additional information about the effect of hydrogen bonds
and structures created by them on the properties of associative liquids.
Despite intense research, there is still no answer to some of the
fundamental questions, including how does the molecular structure affects
the molecular dynamics of alcohols under the influence of various
thermodynamic conditions, whether the increase in pressure will affect the
relaxation dynamics of the alcohol mixture with the non-dissolving solvent?The key task in the course of the conducted research, which form the basis
of the presented doctoral dissertation, was to answer the questions that
concerned issues related to the molecular dynamics of mono- and
polyalcohols:
1) How does the architecture of molecules affect the molecular dynamics of
simple alcohols? What is the role of thermodynamic conditions?
2) In the mixture of 2-ethyl-1-hexanol with 2-ethylhexylbromide (2E1H /
2E1Br) with a sufficiently high alcohol concentration there is the possibility
of simultaneous testing of Debye's and structural relaxation properties also
under high pressure conditions. This in turn gives the opportunity to find
an answer to the question, what is the effect of different thermodynamic
conditions on the dynamics of 2-ethyl-1-hexanol 2E1H dynamics, and in
particular on structural relaxation?
3) How do thermodynamic conditions and differences in the architecture of
molecules, including the addition of a second hydroxyl group, affect the
properties of diols
Density Scaling Based Detection of thermodynamic Regions of complex intermolecular interactions characterizing Supramolecular Structures
In this paper, applying the density scaling idea to an associated liquid 4-methyl-2-pentanol used
as an example, we identify different pressure-volume-temperature ranges within which molecular
dynamics is dominated by either complex H-bonded networks most probably leading to supramolecular
structures or non-specific intermolecular interactions like van der Waals forces. In this way, we show
that the density scaling law for molecular dynamics near the glass transition provides a sensitive tool
to detect thermodynamic regions characterized by intermolecular interactions of different type and
complexity for a given material in the wide pressure-volume-temperature domain even if its typical
form with constant scaling exponent is not obeyed. Moreover, we quantify the observed decoupling
between dielectric and mechanical relaxations of the material in the density scaling regime. The
suggested methods of analyses and their interpretations open new prospects for formulating models
based on proper effective intermolecular potentials describing physicochemical phenomena near the
glass transition
Inflection point in the Debye relaxation time of 2-butyl-1-octanol
International audienceWe report a striking anomaly in the pressure dependent Debye-relaxation time of the branched monohydroxy alcohol 2-butyl-1-octanol. Evidence of a crossover from slower to faster than exponential pressure dependency was obtained at different temperatures via high pressure broadband dielectric spectroscopy. At the same time, viscosity measurements reveal similar behavior in the viscosity respectively the structural relaxation time, indicating a similar origin of the phenomena
Effect of Drugs Used in Pharmacotherapy of Type 2 Diabetes on Bone Density and Risk of Bone Fractures
This review summarizes the complex relationship between medications used to treat type 2 diabetes and bone health. T2DM patients face an increased fracture risk despite higher bone mineral density; thus, we analyzed the impact of key drug classes, including Metformin, Sulphonylureas, SGLT-2 inhibitors, DPP-4 inhibitors, GLP-1 agonists, and Thiazolidinediones. Metformin, despite promising preclinical results, lacks a clear consensus on its role in reducing fracture risk. Sulphonylureas present conflicting data, with potential neutral effects on bone. SGLT-2 inhibitors seem to have a transient impact on serum calcium and phosphorus, but evidence on their fracture association is inconclusive. DPP-4 inhibitors emerge as promising contributors to bone health, and GLP-1 agonists exhibit positive effects on bone metabolism, reducing fracture risk. Thiazolidinediones, however, demonstrate adverse impacts on bone, inducing loss through mesenchymal stem cell effects. Insulin presents a complex relationship with bone health. While it has an anabolic effect on bone mineral density, its role in fracture risk remains inconsistent. In conclusion, a comprehensive understanding of diabetes medications’ impact on bone health is crucial. Further research is needed to formulate clear guidelines for managing bone health in diabetic patients, considering individual profiles, glycemic control, and potential medication-related effects on bone