The Role of Nitrogen-Rich Moieties in the Selection of Arginine's Tautomeric Form at Different Temperatures.

It is well known that the guanidinium group in Arginine plays an important role in noncovalent interactions. However, its role is not well documented since the selection of its global minimum structure is still controversial. The main difficulties on obtaining accurate results lie on:  neutral Arginine can occur in 3 forms, two of which are canonical and one is zwitterion; each form has degenerate enantiomers D- and L-; its numerous degrees of freedom make it challenging to perform a thorough study; the short-range interactions require higher levels of theory to correctly describe them.

Relative Populations and IR Spectra of Cu Cluster at Finite Temperature Based on DFT and Statistical Thermodynamics Calculations.

The relative populations of Cu isomers depend to a great extent on the temperature. Density functional theory and nanothermodynamics can be combined to compute the geometrical optimization of isomers and their spectroscopic properties in an approximate manner. In this article, we investigate entropy-driven isomer distributions of Cu clusters and the effect of temperature on their IR spectra.

Effects of Temperature on Enantiomerization Energy and Distribution of Isomers in the Chiral Cu Cluster.

In this study, we report the lowest energy structure of bare Cu nanoclusters as a pair of enantiomers at room temperature. Moreover, we compute the enantiomerization energy for the interconversion from minus to plus structures in the chiral putative global minimum for temperatures ranging from 20 to 1300 K. Additionally, employing nanothermodynamics, we compute the probabilities of occurrence for each particular isomer as a function of temperature.

Theoretical Prediction of Structures, Vibrational Circular Dichroism, and Infrared Spectra of Chiral BeB Cluster at Different Temperatures.

Lowest-energy structures, the distribution of isomers, and their molecular properties depend significantly on geometry and temperature. Total energy computations using DFT methodology are typically carried out at a temperature of zero K; thereby, entropic contributions to the total energy are neglected, even though functional materials work at finite temperatures. In the present study, the probability of the occurrence of one particular BeB isomer at temperature T is estimated by employing Gibbs free energy computed within the framework of quantum statistical mechanics and nanothermodynamics.

Exploration of Free Energy Surface and Thermal Effects on Relative Population and Infrared Spectrum of the BeB Flux-Ional Cluster.

The starting point to understanding cluster properties is the putative global minimum and all the nearby local energy minima; however, locating them is computationally expensive and difficult. The relative populations and spectroscopic properties that are a function of temperature can be approximately computed by employing statistical thermodynamics. Here, we investigate entropy-driven isomers distribution on BeB clusters and the effect of temperature on their infrared spectroscopy and relative populations.

Chronic stress decreases ornithine decarboxylase expression and protects against 1,2-dimethylhydrazine-induced colon carcinogenesis.

Biological response to stress depends on the type, timing, and severity of the stressor. Acute stressful environments may positively activate molecular and cellular mechanisms to favor adaptation; however, chronic stress is often associated with detrimental health effects. Colon cancer (CC) is one of the leading causes of death associated with cancer and has been mentioned as a stress-related disease.