5‐(5‐Nitropyridin‐2‐yldithio)‐1‐phenyl‐1H‐tetrazole

In the title disulfide, C₁₂H₈N₆O₂S₂, all bond lengths and angles are within normal ranges, and the molecules are linked into centrosymmetric R₂²(20) dimers by simple C—H...N interactions. Weak intermolecular C—H...π(arene) and π–π interactions, involving the benzene CH groups and the benzene rings, and the pyridine rings, respectively, further stabilize and reinforce the crystal structure.     

Molecular structure of aniline in the gaseous phase: A concerted study by electron diffraction and ab initio molecular orbital calculations

The molecular structure of free aniline has been investigated by gas-phase electron diffraction and ab initio MO calculations at the HF and MP2 levels of theory, using the 6-31G^*(6D) basis set. Least-squares refinement of a model withC _s symmetry, with constraints from MP2 calculations, has led to an accurate determination of the C-C-C angle at theipso position of the benzene ring, =119.0±0.2 (where the uncertainty represents total error). This parameter provides information on the extent of the interaction between the nitrogen lone pair and the system of the benzene ring, and could not be determined accurately by microwave spectroscopy. The angles at theortho, meta, andpara positions of the ring are 120.3±0.1, 120.7±0.1, and 119.0±0.3, respectively. Important bond distances are r _g(C-C)=1.398±0.003 å andr _g(C-N) =1.407±0.003 å. The effective dihedral angle between the H-N-H plane and the ring plane, averaged over the large-amplitude inversion motion of the amino group, is ¦¦=44±4. The equilibrium dihedral angle is calculated to be 41.8 at the HF level and 43.6 at the MP2 level, in agreement with far-infrared spectroscopic information. The MO calculations predict that the differencer(C_ortho-C_meta) -r(C_ipso-C_ortho) is 0.008–0.009 å. They also indicate that the nitrogen atom is displaced from the ring plane, on the side opposite to the amino hydrogens. The displacement is 0.049 å at the HF level and 0.072 å at the MP2 level. The two calculations, however, yield very different patterns for the minute deviations from planarity of the ring carbons.     

Synthesis and characterization of a bunchy oligonucleotide forming a monomolecular parallel quadruplex structure in solution

A cluster of four d(TG₄T) hexanucleotides with the 3′-ends linked together by a bunchy spacer has been synthesized and shown to form a monomolecular parallel quadruplex 5 in solution characterized by four G-quartets. ¹H NMR spectroscopy and CD thermal denaturation experiments indicate the monomolecular quadruplex (5) to be more stable than the tetramolecular counterpart [d(TG₄T)]₄.     

On the iteration of the adjunction process for surfaces of negative Kodaira dimension

Let (X,L) be a pair consisting of a smooth, complex, projective surface X and L a very ample line bundle on it. Suppose that the Kodaira dimension K(X) of X is negative. Then using the results obtained by A.J.Sommese and A.Van de Ven in [11], we find that the sectional genus, g_k=g(L_k), of the successive iterated minimal reductions (X_k,L_k), see 1. for the definition, reach a maximum value and then monotonically decrease to a final value g_n=g(L_n)g=g(L). This result gives a concrete way to express any pair (X,L), with K(X)=–, in terms of a minimal model.     

Proteomic profiling of pancreatic ductal carcinoma cell lines treated with trichostatin-A

A pancreatic adenocarcinoma cell line (Paca44) was treated with trichostatin-A (TSA), a potent inhibitor of histone deacetylases, in order to evaluate the effect of this drug on protein expression. Master maps of control and treated Paca44 cells were generated by analysis with the PDQuest software. The comparison between such maps showed up- and downregulation of 51 polypeptide chains, out of a total of 700 spots detected by a medium-sensitivity stain, micellar Coomassie Brilliant Blue. Fingerprinting by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF)-mass spectrometry analysis enabled the identification of 22 of these spots. Among these proteins, of particular interest are the two downregulated proteins nucleophosmin and translationally controlled tumor protein, as well as the upregulated proteins programmed cell death protein 5 (also designated as TFAR19) and stathmin (oncoprotein 18). The modulation of these four proteins is consistent with our observation that TSA is able to inhibit cell growth of Paca44 by causing cell cycle arrest at the G2 phase and apoptotic cell death.     

Structure Determination of an Unusual [2.2]paracyclophane Derivative by NMR Spectroscopy

Our ongoing study on cycloaddition reactions of dienes with different dienophiles afforded a great variety of derivatives with interesting molecular structures and electronic behavior. A new type of angularly annelated [2.2]paracyclophane (3) has been synthesize by the Diels–Alder reaction of 4-(2-propenyl[2.2]paracyclophane (1) and 1,4-benzoquinone (2) under high pressure conditions. The structure determination of this compound has been achieved by NMR measurements and semiempirical calculations.     

Where are embarrassingly parallel problems? The atom-diatom quasiclassical reactivity

Summary The apparently embarrassingly parallel problem of calculating a batch of quasiclassical trajectories to evaluate cross sections or rate constants has been analyzed. The study shows that only an accurate evaluation of the performance parameters and a consequent appropriate restructuring of the computer code allows the achievement of high speedup and efficiency especially when large calculations are implemented on massively parallel systems.     

A proteomic approach to study protein variation in GM durum wheat in relation to technological properties of semolina

Genetic manipulation of durum wheats by tobacco rab-1 genes influence the trafficking of gluten proteins through the secretory system by up- or down-regulating the transport step from the ER to the Golgi apparatus which may in turn modify functional performance of the grain. Gluten proteins were extracted from two genetically manipulated lines - Svevo B730 1-1 and Ofanto B688 1-2 - and their control lines and were analyzed by two dimensional gel electrophoresis. When the two-dimensional maps were compared by image analysis no significant differences between the GM line with an up-regulated trafficking containing the wild type tobacco rab1 (Svevo B730 1-1) and its control (Svevo control). By contrast, significant differences were found between the GM line with a down-regulated trafficking due to the tobacco rab1 mutant form (Ofanto B688 1-2) and its control (Ofanto control). Of the new protein spots detected in the down-regulated Ofanto B688 1-2 map, only a beta-amylase was identified. The remaining spots were susceptible to chymotripsin action but not to trypsin one, as in the case of the gluten protein. Rheological measurements showed that gluten quality was enhanced in the down-regulated Ofanto B688 1-2 without an increase in the amount of gluten. Proteomics is a useful and powerful tool for investigating protein changes in GMOs and in understanding events in food science and technology.     

A molecular dynamics investigation of rare-gas solvated cation-benzene clusters using a new model potential

The main static and dynamic properties of some ionic heteroclusters, involving K+, C6H6, and Ar, have been investigated. A new representation of the intermolecular potential energy, which takes into account both electrostatic and non-electrostatic contributions to the overall noncovalent interaction, was used. Dynamical calculations were performed for a microcanonical ensemble. Particular attention was paid to the opening of the isomerization and dissociation processes for K+-C6H6-Ar(n) and to the formation of some of its fragments at increasing temperatures of the cluster considered.     

Interpretation of electronic spectra of aromatic hydrocarbons by the “molecules in molecules” method

The molecules in molecules method has been applied to five groups of hydrocarbon molecules or ions. Energy, polarisation and intensity of electronic transitions have been compared with experimental data and previous theoretical results. The results show that the method is applicable even when there is relevant conjugation between the fragments.

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Zusammenfassung Die molecules in molecules-Methode wurde auf fünf Gruppen von Kohlenwasserstoff-Molekülen angewandt. Energie, Polarisation und Intensität von elektronischen Übergängen wurden mit experimentellen und theoretischen Resultaten verglichen. Die Resultate beweisen, daß die Methode anwendbar ist, auch wenn eine wesentliche Konjugation zwischen den Fragmenten besteht.

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Resumé La méthode molecules in molecules a té appliquée à cinq groupes de molécules ou ions d'hydrocarbures. On a comparé les energies, la polarisation et l'intensité des transitions électroniques avec les données experimentales et les données théoriques qu'on avait précedemment calculées. Les résultats indiquent que la méthode est appliquable, même lorsqu'on a une conjugation assez importante entre les fragments.