Pentaerythritol/quaternary ammonium eutectic mixture as an ionic solvent: the quaternary ammonium cations can be easily controlled to exert their structure-directing effect in ionothermal synthesis of aluminophosphate microporous materials.

Prevention is primarily categorized as Primordial, Primary, Secondary and Tertiary. Now the concept of "Quaternary Prevention" is also introduced. This editorial article discusses need of Quaternary prevention in current scenario of clinical practice.

To understand why the classical two-state allosteric model of Monod, Wyman, and Changeux explains cooperative oxygen binding by hemoglobin but does not explain changes in oxygen affinity by allosteric inhibitors, we have investigated the kinetic properties of unstable conformations transiently trapped by encapsulation in silica gels. Conformational trapping reveals that after nanosecond photodi...

Tea saponin of functional ingredients extracted from camellia meal, is China's unique natural functional molecules. With silicone oil containing hydrogen and unsaturated polyether silicon hydrogenation reaction, and then esterification with tea saponin, and the tertiary amine hydrochloride reaction of tea saponin was modified organosilicon quaternary ammonium salt and its conversion rate reache...

"Protein quaternary structure universe" refers to the ensemble of all protein-protein complexes across all organisms in nature. The number of quaternary folds thus corresponds to the number of ways proteins physically interact with other proteins. This study focuses on answering two basic questions: Whether the number of protein-protein interactions is limited and, if yes, how many different qu...

Quaternary ammonium compounds are an important class of molecules with wide variety of applications, mainly in the antimicrobial field. Quaternary ammonium compounds have the ability to bind with the anionic moiety of phospholipids of the bacterial membrane, disrupting the cell membrane of the microorganisms. However, classical quaternary ammonium salts can have adverse effects on the environme...

The aim of this study was to develop a derivative of chitosan as pharmaceutical excipient used in sustained-release matrix tablets of poorly soluble drugs. A water-soluble quaternary ammonium carboxymethylchitosan was synthesized by a two-step reaction with carboxymethylchitosan (CMCTS), decylalkyl dimethyl ammonium and epichlorohydrin. The elemental analysis showed that the target product with...

Protein allostery is essential for vital activities. Allosteric regulation of human hemoglobin (HbA) with two quaternary states T and R has been a paradigm of allosteric structural regulation of proteins. It is widely accepted that oxygen molecules (O2) act as a "site-specific" homotropic effector, or the successive O2 binding to the heme brings about the quaternary regulation. However, here we...

Lithiation of carbamates followed by borylation provides a powerful method for the homologation of boron reagents. However, when applied to hindered systems (secondary carbamates with tBu-boronic esters) for the construction of two quaternary centers, this methodology fails. Instead, using mixed boranes (tBuBMe2), the synthesis of adjacent quaternary stereogenic centers with full stereocontrol ...