Density functional theory calculations of adsorption-induced surface stress changes

Density functional theory calculations of adsorbate-induced surface stress changes have been performed for a number of adsorbate and overlayer systems for which experimental data exists, namely: oxygen and sulphur adsorption on Ni(1 0 0); oxygen adsorption on W(1 1 0); pseudomorphic growth of Ni on Cu(1 0 0) and of Fe on W(1 1 0); oxygen adsorption on a 5 ML pseudomorphic film of Ni(1 0 0) grown on Cu(1 0 0). The theoretical calculations reproduce all the qualitative features of the experimental data, but there are some significant quantitative differences, most notably for the two atomic adsorbates on the bulk Ni(1 0 0) surface, for which the theoretical stress changes are substantially smaller than the experimental ones, a situation not obviously attributable to experimental error. For the W(1 1 0)/Fe system there is also a marked difference between experiment and theory in the coverage at which key surface stress changes occur

Comparison of boron-assisted oxime and hydrazone formations leads to the discovery of a fluorogenic variant

We use kinetic data, photophysical properties, and mechanistic analyses to compare recently developed high-rate constant oxime and hydrazone formations. We show that when Schiff base formation between aldehydes and arylhydrazines is carried out with an appropriately positioned boron atom, then aromatic B–N heterocycles form irreversibly. These consist of an extended aromatic structure amenable to the tailoring of specific properties such as reaction rate and fluorescence. The reactions work best in neutral aqueous buffer and can be designed to be fluorogenic – properties which are particularly interesting in bioconjugation

Stress busters to the rescue

The Thurman Center co-hosted activities for students to relax before final exams.Educational Resource CenterOffice of Residence Lif

Oneiric stress and safety and security at work: the discovery of a new universal symbol

Cox and Griffiths define as psychosocial risks at work “those aspects of the planning, organization and management of work, which, along with their environmental and social contexts, may affect mental and physical health of the employees, directly or indirectly producing stress”. Therefore, a more effective approach to occupational safety and security should include integrated risk management through the identification of any work stress related problem. The purpose of this paper is to analyze the possible correlation of risk at work with the modification of sleep, and inside it, the specific function of dream activity

STRENGTHENING (POST-STRESS) OF MASONRY BUILDINGS METHOD OF VERTICALIZATION OF LOAD

Um método para recuperação das fendas nos arcos em alvenaria

Aqueous synthetic methods and their applications in DNA-encoded chemical libraries

Water is the basis for all living organisms on Earth and most biochemical processes proceed in aqueous environments. To study biological systems, chemists have developed numerous procedures to perform chemical transformations in the presence of water. However, there is still a limited scope of reactions that proceed efficiently and reliably under physiological conditions. The search for new techniques to enable selective and reliable modifications of biomolecules and small molecules alike, has attracted the attention of many researchers in academia and industry. Such "water-friendly" reactions are highly desired for different areas of biochemical research, such as bioconjugation techniques and drug discovery procedures. Schiff base formation is a workhorse in bioconjugation science, although the reactions proceed slowly under neutral conditions without catalysts. We investigated oxime and hydrazone formations of ortho-boronate carbonyl compounds with hydroxylamines and hydrazines. The boronic acid was found to strongly increase the Schiff base formation rate, which enabled the fluorescent labeling of antibodies. Hydrazones with an adjacent boronic acid group undergo a secondary cyclization reaction to form a stable, aromatic boron-heterocycle (BIQ, 4,3-borazaroisoquinoline). Upon modulation of the electronic properties of this boron-heterocycle with different substituents, we developed a blue fluorophore that formed upon cyclization to the BIQ product. Based on the results from the bioconjugation techniques, we developed a library of macrocycles, in which every compound was attached to a DNA strand containing the information about the macrocycle structure. Despite initial difficulties, we obtained a 1.4 million member DNA-encoded library of natural product-like macrocycles with high scaffold diversity. After thorough analysis of the library properties, we screened the encoded macrocylce collection against three human proteins. Several hits were found and resynthesized without DNA tag. Binding affinities to the target proteins were evaluated by biophysical techniques. Differential scanning fluorimetry enabled the parallel screening of the hit compounds, giving a qualitative measurement for the protein affinities. Isothermal titration calorimetry yielded quantitative dissociation rate constants for the most promising compounds. We discovered a novel macrocyclic ligand for α-1-acid glycoprotein (AGP) with a low micromolar affinity, which holds promise for the development of new drug candidates. The developed encoded library methodology was shown to be well suited for early stage drug discovery

Stress and depression among veterinary medical students

While existing literature suggests that professional students (e.g., medical, dental, law, nursing, etc.) experience high levels of stress and depression, the experiences of veterinary medical students have been less well examined. The purpose of this study was to explore the levels of stress and depression among veterinary medical students and to examine the relationship between these variables. Study participants were 1,245 veterinary medical students from North America. The findings provide support for the assertion that veterinary medical students experience high levels of stress and depression. Results also indicated that there is a correlation between stress and depression for veterinary medical students and that female students experience higher levels of stress and depression than their male counterparts.Accepted manuscrip