Discussions

The increasing number of severe smog weather has aroused public concern. Organic nitrate (RONO2) is an important precursor for the formation of smog and secondary organic aerosol (SOA), but its source is not fully understood. Exploring the formation mechanism of RONO2 in the atmosphere has far-reaching significance for understanding the causes of smog particles and improving air quality. However, for all known sources of RONO2, discrepancies exist between field measurements of its concentration and reported sources of formation, suggesting that there must be an important and as yet unknown source for RONO2.
Recently, some researchers used the density functional theory M06-2X method combined with the 6-311+G(d,p) basis set to optimize the geometric structures of all reactants, complexes, transition states and products, and calculated the harmonic frequencies of all stagnation points at the same level. At the same time, the single-point energy correction of all stagnation points was carried out by using the high-level CCSD(T) method combined with the complete basis set (CBS) method calculated by the combination of aug-cc-pVDZ and aug-cc-pVTZ basis sets. The results show that HNO3 and HCHO can directly generate hydroxymethyl nitrate (HOCH2ONO2) by overcoming the energy barrier of 16.73 kcal/mol, with a rate constant of 1.87×10-22 cm3 molecule-1 s-1 at 296 K. In addition, as the carbon chain grows (C1-C5), the activation energy of RONO2 decreases successively, which are 7.87, 5.33, 5.01, 4.97 and 4.85 kcal/mol, respectively, and the reaction rate constant at room temperature increases successively from 1.87×10-22 to 6.77×10-21cm3 molecule-1 s-1, indicating that there may be a positive correlation between the reactivity and the electron-donating ability of the group. At the same time, the HOMO-LUMO energy gap values of transition states TS1-TS5 are calculated, which are 217.90, 216.91, 215.71, 215.59 and 215.54 kcal/mol, respectively. It can be seen that the same type of energy gap decreases and the law of energy barrier and rate changes is consistent, and further illustrates the positive correlation between carbon chain length and reactivity.

Tetracycline is an organic compound with the molecular formula C22H24N2O8. It and its salts are yellow or light yellow crystals. They are extremely stable in a dry state. Except for chloramphenicol, the aqueous solutions of other tetracyclines are quite stable. Tetracyclines are soluble in dilute acids and alkalis, slightly soluble in water and lower alcohols, but insoluble in ether and petroleum ether.

In recent years, the fight against cancer has seen significant advances, particularly with the emergence of targeted therapy. Among the most promising strategies in this domain is the development of radioactive drug conjugates(RDCs). These innovative therapeutic agents combine the targeting capabilities of antibodies with the cytotoxic effects of radioactive isotopes, providing a powerful strategy for precision cancer treatment.

Alfa Cytology has officially released its antibody-drug conjugates(ADCs) development services which demonstrates the dedication to fighting cancer through advanced treatment methods.

Find creative inspiration in architecture, people, and street scenes with composition techniques and editing ideas that highlight urban beauty.

Negative space can simplify your composition and highlight your subject. Learn how to balance subject placement with empty space for powerful, uncluttered images that speak volumes.

Learn how to use depth of field to create artistic effects, such as blurred backgrounds in portraits or deep focus in landscapes, by adjusting aperture and focal length settings.

Excessive screen time leads to eye strain, poor posture, and mental fatigue. Taking breaks, adjusting lighting, and practicing digital detoxes improve well-being.