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The synthesis and chromatographic characterization of a highly crosslinked self-assembled monolayer (SAM) stationary phase whose acid and thermal stability were significantly improved relative to a sterically protected octadecylsilane (ODS) stationary phase were recently described [B.C. Trammell, L. Ma, H. Luo, D. Jin, M.A. Hillmyer, P.W. Carr, Anal. Chem. 74 (2002) 4634]. Unfortunately, this highly crosslinked SAM phase is much more silanophilic than a conventional sterically protected octadecyl silane phase. 29Si CP-MAS NMR analysis shows that the high concentration of silanol groups in the self-assembled monolayer causes the increased retention and poor peak shape of basic solutes. In this work dimethyl-chloromethyl-phenylethylchlorosilane (DM-CMPES), a silane with only a single reactive silyl chloride group was tested as an alternative to chloromethyl-phenyethyltrichlorosilane (CMPES) as the basis for forming the starting phase. Most importantly this "conventional" silanization step (i.e., a non-SAM silanization) was followed by a Friedel-Crafts reaction using aluminum chloride as the catalyst and styrene heptamer as the multi-valent crosslinker to form the surface DM-CMPES groups into a network polymer which is fully confined and attached to the surface. An octyl (C8) derivative of the hypercrosslinked (HC) dimethyl-chloromethyl-phenylethyl (DM-CMPES) surface-confined stationary phase was synthesized to demonstrate the potential of a Friedel-Crafts based approach to making high efficiency, acid and thermally stable polymerized phases on silica with selectivity closer to conventional aliphatic phases. The stability of the retention factors of these phases under very aggressive conditions (5%, (v/v) trifluoroacetic acid and 150 degrees C) are compared to that of a sterically protected octadecylsilane (ODS) phase. The comparisons show that the long term stability of highly crosslinked DM-CMPES phases in acid is superior to the conventional phase. The HC-C8 phase is even more stable in acid than the HC-styrene heptamer DM-CMPES phase on which it is based. Additionally, the efficiency and peak shape of several prototypical bases under acidic (0.1% TFA, pH 2.0) elution conditions are discussed. The column dynamics and thermodynamic characteristics of the HC-C8 phase were investigated to demonstrate the chromatographic utility of this ultra-stable phase. Inverse size exclusion chromatography and flow studies of the HC-C8 and the sterically protected C18 stationary phases indicate the absence of pore plugging and quite good (nearly 100,000 plates/m) chromatographic efficiency. Further chromatographic investigations show that the HC-C8 stationary phase behaves as a typical reversed phase material. The HC-C8 stationary phase offers unique chromatographic selectivity for certain classes of analytes compared to both alkyl and phenyl bonded phases.

G protein-gated inwardly rectifying K+ (GIRK/Kir3) channels exert a critical inhibitory influence on neurons. Neuronal GIRK channels mediate the G protein-dependent, direct/postsynaptic inhibitory effect of many neurotransmitters including γ-aminobutyric acid (GABA), serotonin, dopamine, adenosine, somatostatin, and enkephalin. In addition to their complex regulation by G proteins, neuronal GIRK channel activity is sensitive to PIP2, phosphorylation, regulator of G protein signaling (RGS) proteins, intracellular Na+ and Ca2+, and cholesterol. The application of genetic and viral manipulations in rodent models, together with recent progress in the development of GIRK channel modulators, has increased our understanding of the physiological and behavioral impact of neuronal GIRK channels. Work in rodent models has also revealed that neuronal GIRK channel activity is modified, transiently or persistently, by various stimuli including exposure drugs of abuse, changes in neuronal activity patterns, and aversive experience. A growing body of preclinical and clinical evidence suggests that dysregulation of GIRK channel activity contributes to neurological diseases and disorders. The primary goals of this review are to highlight fundamental principles of neuronal GIRK channel biology, mechanisms of GIRK channel regulation and plasticity, the nascent landscape of GIRK channel pharmacology, and the potential relevance of GIRK channels to the pathophysiology and treatment of neurological diseases and disorders.

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An irregularity index IR(Γ) of a graph Γ is a nonnegative numeric quantity (i.e., IR(Γ)≥0) such that IR(Γ)=0 iff Γ is a regular graph. In this paper, we show that IRC closely correlates with the normal boiling point Tbp and the standard heat of formation ΔHfo of lower benzenoid hydrocarbons. The correlation models that fit the data efficiently for both Tbp and ΔHfo are linear. We develop further mathematical properties of IRC by calculating its exact expressions for the recently introduced transformation graphs as well as certain derived graphs, such as the total graph, semi-total point graph, subdivision graph, semi-total line graph, double, strong double, and extended double cover graphs. Some open problems are proposed for further research on the IRC index of graphs.