Spontaneous parity violation and minimal Higgs models

In this paper we present a model for the spontaneous breaking of parity with two Higgs doublets and two neutral Higgs singlets which are even and odd under -parity. The condition can be satisfied without introducing bidoublets, and it is induced by the breaking of -parity through the vacuum expectation value of the odd Higgs singlet. Examples of left–right symmetric and mirror fermions models in grand unified theories are presented. PACS 12.60.Cn; 14.80.Cp; 12.10.Dm     

Electroanalytical Determination of Estrone in Seawater Samples Using Functionalized Multiwalled Carbon Nanotubes

In this work, a glassy carbon electrode (GCE) modified with multiwalled carbon nanotubes functionalized with carboxylic groups (MWCNT−COOH) was used to determine the hormone estrone in seawater samples. Modification of the electrode was optimized using three successive 10-μL aliquots of the MWCNT−COOH dispersion in ethanol (1 : 5 mL). The cyclic voltammetry results showed an oxidation peak at 0.59 V with characteristics of an irreversible process, pH dependent and controlled by adsorption of species. The results of square-wave voltammetry showed that the intensities of peak currents for the MWCNT−COOH/GCE were about 2.5 times higher than for GCE. The calibration curve showed a linearity of 0.9981 and a sensitivity of 0.1521 μA/mol L⁻¹. The limits of detection and quantification were 0.117 and 0.392 μmol L⁻¹, respectively. The recovery obtained using seawater samples was 91%, indicating the applicability of the method in marine environments.     

Energetics of the allyl group

Aiming to improve our understanding of the stability of radicals containing the allylic moiety, carbon-hydrogen bond dissociation enthalpies (BDEs) in propene, isobutene, 1-butene, (E)-2-butene, 3-metylbut-1-ene, (E)-2-pentene, (E)-1,3-pentadiene, 1,4-pentadiene, cyclohexene, 1,3-cyclohexadiene, and 1,4-cyclohexadiene have been determined by quantum chemistry calculations. The BDEs in cyclohexene, 1,3-cyclohexadiene, and 1,4-cyclohexadiene have also been obtained by time-resolved photoacoustic calorimetry. The theoretical study involved a DFT method as well as ab initio complete basis-set approaches, including the composite CBS-Q and CBS-QB3 procedures, and basis-set extrapolated coupled-cluster calculations (CCSD(T)). By taking the C(sp3)-H BDE in propene as a reference, we have concluded that one methyl group bonded to C3 in propene (i.e., 1-butene) leads to a decrease of 12 kJ mol(-1) and that a second methyl group bonded to C3 (3-methylbut-1-ene) further decreases the BDE by 8 kJ mol(-1). When the methyl group is bonded to C2 in propene (isobutene), an increase of 7 kJ mol(-1) is observed. Finally, a methyl group bonded to C1 in propene (2-butene) has essentially no effect (-1 kJ mol(-1)). While this trend can be rationalized in terms of stabilization of the corresponding radical (through hyperconjugation and pi-delocalization), the BDE values observed for the dienes can only be understood by considering the thermodynamic stabilities of the parent compounds.     

Rapid characterization of alkylpolyphosphonates by CZE with indirect photometric and mass spectrometric detection

Methods for the rapid characterization of industrial alkylpolyphosphonates (APPs) by infusion MS and CZE with indirect photometric (IPD) and MS detection are described. Technical-grade APPs, including alkylaminepolyphosphonates with 3-5 phosphonate groups and different hydrocarbon skeletons, hydroxyethyl-amino-bis(methylenephosphonic acid), hydroxyethylidene-diphosphonic acid, and 2-phosphonobutane-1,2,4-tricarboxylic acid, were examined. A 10 mM solution of adenosine triphosphate disodium salt at pH 2.2 was used as BGE. The nominal compounds of the industrial APPs and their impurities were well resolved in less than 15 min. The peaks were identified by using extracted ion electropherograms, which were obtained at the m/z values indicated by the peaks of the infusion spectra. Low concentrations of esters, anhydrides, and APPs having different hydrocarbon skeletons compared to nominal compounds, and lacking phosphonate and methylene-phosphonate groups with respect to them, were found. Also, hydroxyethyl-aminobis(methylenephosphonic acid) contained an intramolecular ester at a concentration close to that of the nominal compound. Application of CZE-IPD and CZE-MS to the quality control of industrial APPs, and of CZE-MS to the identification and characterization of APPs in cleaning products, was demonstrated.     

Mass distribution, polydispersity, and focusing properties of carrier ampholytes for IEF. Part V: pH 9-11 interval

As a last part of an investigation on all 2-pH-unit intervals of carrier ampholytes (CAs) for IEF (see Electrophoresis 2006, 27, 3919-3934; 2006, 27, 4849-4858; 2007, 28, 715-723) two different lots of Servalyt CAs, in the pH 9-11 range, have been analyzed by a 2-D technique based on preparative Rotofor fractionation followed by capillary electrophoresis mass-spectrometry of 10 out of 20 fractions harvested, in the second dimension. The findings: the two lots contain 65 and 69 different M(r) compounds, in the M(r) interval of 232-667 Da, for a total of 341-387 isoforms, respectively. Since this is a chaotic organic synthesis, the high reproducibility (here demonstrated for the first time during the 40 years of existence of CAs) of the synthetic process (for two batches produced at 6 years of distance) is remarkable, considering that a 94% agreement for the individual chemicals and 88% agreement for the total number of isoforms for the two lots is found. It is additionally demonstrated that the lower pI species are accompanied by considerably more isoforms than the high pI forms and that in all cases such isoforms consist of family of compounds clustered around the pI of the parental form, with a pI spread of ca. 0.1-0.2 pH units.     

Production of cellulolytic and hemicellulolytic enzymes from Aureobasidium pulluans on solid state fermentation

This article investigates a strain of the yeast Aureobasidium pullulans for cellulase and hemicellulase production in solid state fermentation. Among the substrates analyzed, the wheat bran culture presented the highest enzymatic production (1.05 U/mL endoglucanase, 1.3 U/mL beta-glucosidase, and 5.0 U/mL xylanase). Avicelase activity was not detected. The optimum pH and temperature for xylanase, endoglucanase and beta-glucosidase were 5.0 and 50, 4.5 and 60, 4.0 and 75 degrees C, respectively. These enzymes remained stable between a wide range of pH. The beta-glucosidase was the most thermostable enzyme, remaining 100% active when incubated at 75 degrees C for 1 h.     

Synthesis and structure of some azo coupled cyclic beta-enaminones

The reaction of 3-phenylaminocyclopent-2-en-1-one with 4-methyl, 4-methoxy and 4-chlorobenzenediazonium tetrafluoroborates was used to prepare the azo coupling products 3a-c. It was found that these compounds are present in both CDCl(3) solution and solid phase practically exclusively as (E)-3-phenylamino-2-(4-subst.phenyldiazenyl)cyclopent-2-en-1-ones with N--H...N intramolecular hydrogen bond. The substitution of the phenyl residue of the diazonium salt has no effect on the position of the tautomeric equilibrium. On the other hand, the compounds 4a, b formed by the reaction of 3-phenylamino-1H-inden-1-one with 4-methylbenzene- or benzenediazonium tetrafluoroborates exist in CDCl(3) solution and in solid phase as hydrazone compounds. In the solution they occur as a mixture of three forms, out of which two were identified as E/Z isomers with different types of hydrogen bonds. Compound 5 formed by the reaction of 3-amino-5,5-dimethylcyclohex-2-en-1-one with 4-methoxybenzenediazonium tetrafluoroborate is converted into a stable hydrochloride 5.HCl on standing in CHCl(3) solution; this product exhibits a high degree of delocalization of the positive charge. Its structure was studied by means of X-ray.     

Enantioselective total synthesis of 1-epi-pathylactone A

[structure: see text]. The first enantioselective total synthesis of 1-epi-pathylactone A, 3, has been accomplished using a PhI(OAc)2-mediated domino reaction as a key step. No diastereomeric separation was required throughout the whole synthetic scheme presented in this paper. Comparison of 1H and 13C NMR spectral data of the synthetic product with the reported spectral data of natural pathylactone A, coupled with an X-ray crystallographic analysis, led to the conclusion that the C1 configuration in the original paper was erroneously ascribed to (R).     

Asymmetric synthesis of (+)-cis-nemorensic acid from a chiral Diels-Alder adduct of 2,5-dimethylfuran

(+)-cis-Nemorensic acid was synthesized from a chiral Diels-Alder adduct prepared by a catalytic enantioselective Diels-Alder reaction with 2,5-dimethylfuran and 2,2,2-trifluoroethyl acrylate.     

Ultrathin zirconium disulfide nanodiscs

We present a colloidal route for the synthesis of ultrathin ZrS(2) (UT-ZrS(2)) nanodiscs that are ~1.6 nm thick and consist of approximately two unit cells of S-Zr-S. The lateral size of the discs can be tuned to 20, 35, or 60 nm while their thickness is kept constant. Under the appropriate conditions, these individual discs can self-assemble into face-to-face-stacked structures containing multiple discs. Because the S-Zr-S layers within individual discs are held together by weak van der Waals interactions, each UT-ZrS(2) disc provides spaces that can serve as host sites for intercalation. When we tested UT-ZrS(2) discs as anodic materials for Li(+) intercalation, they showed excellent nanoscale size effects, enhancing the discharge capacity by 230% and greatly improving the stability in comparison with bulk ZrS(2). The nanoscale size effect was especially prominent for their performance in fast charging/discharging cycles, where an 88% average recovery of reversible capacity was observed for UT-ZrS(2) discs with a lateral diameter of 20 nm. The nanoscale thickness and lateral size of UT-ZrS(2) discs are critical for fast and reliable intercalation cycling because those dimensions both increase the surface area and provide open edges that enhance the diffusion kinetics for guest molecules.