A New Generation of Smart Amine Donors for Transaminase‐Mediated Biotransformations

The application of ω‐transaminase biocatalysts for the synthesis of optically pure chiral amines presents a number of challenges, including difficulties associated with displacing the challenging reaction equilibria. Herein, we report a highly effective approach using low equivalents of the new diamine donor, cadaverine, which enables high conversions of challenging substrates to the corresponding chiral amines in excellent ee. This approach paves the way for the design of self‐sufficient fermentation processes combining transaminase biotransformations with existing strategies for cadaverine production by decarboxylation of endogenous lysine.     

Proventriculus of Cephalotes ants: A structural and comparative analysis

The use of optic microscopy and scanning electron microscopy propitiated the comparative examination of the structure of the proventriculus bulb of Cephalotes atratus, Cephalotes clypeatus and Cephalotes pusillus. This portion of the digestive tract possesses highly sclerotized projections which act in the selection of victuals. This structure is of importance to phylogeny studies and thus was compared with others known species of ants in a dendrogram adapted from Eisner (1957). We did not detect differences among the three studied species in the nature of histochemistry and ultra morphology.     

Phosphinoferrocenylaminophosphines as novel and practical ligands for asymmetric catalysis

[structure: see text] A new series of ligands with a novel phosphine-aminophosphine ligation design as depicted in structure 1 has been prepared on a ferrocenylethyl backbone. These BoPhoz ligands of structure 2 have afforded exceedingly high activity and enantioselectivity in the rhodium-catalyzed asymmetric hydrogenation of dehydro-alpha-amino acid derivatives, itaconic acids, and alpha-ketoesters. These air-stable ligands are readily prepared from cost-effective and non-pyrophoric intermediates.     

Approximations of open quotient and speed quotient from glottal airflow and egg waveforms : Effects of measurement criteria and sound pressure level

Noninvasive measures of vocal fold activity are useful for describingnormal and disordered voice production. Measures of open and speed quotient from glottal airflow and electroglottographic (EGG) waveforms have been used to describe timing events associated with vocal fold vibration. To date, there has been little consistency in the measurement criteria used to calculate quotient values. In this study, criteria of 20% and 50% were applied to the AC amplitude of glottal airflow and inverted EGG waveforms for measurement of open quotient. Criteria of 20%, 50%, and 80%, and a midslope criterion that segmented the waveform between 20% and 80% of the waveform amplitude, were used for the calculation of speed quotient. Subjects produced waveforms at sound pressure levels (SPL) of 70, 75, 80 and 85 dB. Results indicated that approximations of open quotient obtained from the glottal airflow waveform significantly decreased using both the 20% and 50% criteria as SPL increased from 80 to 85 dB. No significant changes were found in open quotient from the EGG waveform as a function of SPL. Results of speed quotient measures from the glottal airflow and EGG waveforms showed a generally increasing trend as SPL increased, although the differences were not statistically significant. The data suggest that the signal type, measurement criterion and SPL must be considered in interpreting quotient measures.     

Deflagrations and detonations in thermonuclear supernovae

We study a type Ia supernova explosion using three-dimensional numerical simulations based on reactive fluid dynamics. We consider a delayed-detonation model that assumes a deflagration-to-detonation transition. In contrast with the pure deflagration model, the delayed-detonation model releases enough energy to account for a healthy explosion, and does not leave carbon, oxygen, and intermediate-mass elements in central parts of a white dwarf. This removes the key disagreement between simulations and observations, and makes a delayed detonation the mostly likely mechanism for type Ia supernovae.     

Measurement of the total active 8B solar neutrino flux at the Sudbury Neutrino Observatory with enhanced neutral current sensitivity

The Sudbury Neutrino Observatory has precisely determined the total active (nu(x)) 8B solar neutrino flux without assumptions about the energy dependence of the nu(e) survival probability. The measurements were made with dissolved NaCl in heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be 5.21 +/- 0.27(stat)+/-0.38(syst) x 10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields Deltam(2)=7.1(+1.2)(-0.6) x 10(-5) eV(2) and theta=32.5(+2.4)(-2.3) degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations.     

Addition patterns in carbon allotropes: independence numbers and d-codes in the Klein and related graphs

The problem of predicting stoichiometries and patterns of chemical addition to a carbon framework, subject solely to the restriction that each addend excludes neighboring sites up to some distance d, is equivalent to determination of d-codes of a graph, and for d = 2 to determination of maximum independent sets. Sizes, symmetries, and numbers of d-codes are found for the all-heptagon Klein graph (prototype for "plumber's nightmare" carbon) and for three related graphs. The independence number of the Klein graph is 23, which increases to 24 for a related, but sterically relaxed, all-heptagon network with the same number of vertices and modified adjacencies. Expansion of the Klein graph and its relaxed analogue by insertion of hexagonal faces to form leapfrog graphs also allows all heptagons to achieve their maximum of 3 addends. Consideration of the pi system that is the complement of the addition pattern imposes a closed-shell requirement on the adjacency spectrum, which typically reduces the size of acceptable independent sets. The closed-shell independence numbers of the Klein graph and its relaxed analogue are 18 and 20, respectively.     

Nuclear inelastic scattering spectroscopy of iron-sulfur cubane compounds

The potential of NIS spectroscopy to study the iron-sulfur clusters in metalloproteins is illustrated using model compounds. The origin of the intense low energy transfer bands is discussed.     

A catalogue of isomerization transformations of fullerene polyhedra

Representation of isomerization and carbon insertion or extrusion mechanisms as patch replacements on a fullerene surface allows construction of a catalogue of topologically distinct local transformations of fullerenes, classified by patch boundary and pentagon content. All isomerization patches and isomerization pairs containing up to five pentagons and with an upper limit for the boundary length depending on the number of pentagons are listed. Several infinite series of transformations are identified.