Diethyl 4-(2,4-dichlorophenyl)-2,6-dimethyl 1,4-dihydropyridine-3,5-dicarboxylate

In the title compound, C19H21Cl2NO4, the dihydropyridine ring adopts a flattened boat conformation. The dichlorophenyl ring is oriented almost perpendicular to the planar part of the dihydropyridine ring [dihedral angle = 89.1 (1)degrees]. An intramolecular C-H center dot center dot center dot O hydrogen bond is observed. In the crystal structure, molecules are linked into chains along the b axis by N-H center dot center dot center dot O hydrogen bonds.

3-Methyl-5-phenyl-1-(3-phenylisoquinolin-1-yl)-1H-pyrazole

The title compound, C25H19N3, is composed of an aryl-substituted pyrazole ring connected to an aryl-substituted isoquinoline ring system with a dihedral angle of 52.7 (1)degrees between the pyrazole ring and the isoquinoline ring system. The dihedral angle between the pyrazole ring and the phenyl ring attached to it is 27.4 (1)degrees and the dihedral angle between the isoquinoline ring system and the phenyl ring attached to it is 19.6 (1)degrees.

2-[2-(Hydroxymethyl)phenyl]-1-(1-naphthyl)ethanol

The molecular conformation of the title compound, C19H18O2, is stabilized by an intramolecular O-H-O hydrogen bond. In addition, intermolecular O-H-O interactions link the molecules into zigzag chains running along the c axis.

5-Phenyl-3-(2-thienyl)-1,2,4-triazolo[3,4-a]isoquinoline

In the title molecule, C20H13N3S, the triazoloisoquinoline ring system is approximately planar, with an r.m.s. deviation of 0.045 angstrom and a maximum deviation of 0.090 (2) angstrom from the mean plane for the triazole ring C atom which is bonded to the thiophene ring. The phenyl ring is twisted by 52.0 (1)degrees with respect to the mean plane of the triazoloisoquinoline ring system. The thiophene ring is rotationally disordered by approximately 180 degrees over two sites, the ratio of refined occupancies being 0.73 (1): 0.27 (1).

Expression, purification and X-ray analysis of 1,3-propanediol dehydrogenase (Aq_1145) from Aquifex aeolicus VF5

1,3-Propanediol dehydrogenase is an enzyme that catalyzes the oxidation of 1,3-propanediol to 3-hydroxypropanal with the simultaneous reduction of NADP(+) to NADPH. SeMet-labelled 1,3-propanediol dehydrogenase protein from the hyperthermophilic bacterium Aquifex aeolicus VF5 was overexpressed in Escherichia coli and purified to homogeneity. Crystals of this protein were grown from an acidic buffer with ammonium sulfate as the precipitant. Single-wavelength data were collected at the selenium peak to a resolution of 2.4 angstrom. The crystal belonged to space group P3(2), with unit-cell parameters a = b = 142.19, c = 123.34 angstrom. The structure contained two dimers in the asymmetric unit and was solved by the MR-SAD approach.

2-(4-Chloro-3-nitrophenyl)-4-(4-chlorophenyl)-1,3-thiazole

The title compound, C15H8Cl2N2O2S, crystallizes with two molecules in the asymmetric unit. The dihedral angles between the 4-chloro-3-nitrophenyl ring and the thiazole ring are 0.5 (1) and 7.1 (1)° and those between the 4-chlorophenyl ring and the thiazole ring are 7.1 (1) and 7.4 (1)° in the two molecules. The crystal structure is stabilized by intermolecular C-H...Cl and C-H...O hydrogen bonds.

2-[(E)-(4-hydroxy-3-methoxybenzylidene)amino]-N-(2-methylphenyl)-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxamide

The title compound, C24H24N2O3S, exhibits antifungal and antibacterial properties. The compound crystallizes with two molecules in the asymmetric unit, with one molecule exhibiting 'orientational disorder' in the crystal structure with respect to the cyclohexene ring. The o-toluidine groups in both molecules are noncoplanar with the respective cyclohexene-fused thiophene ring. In both molecules, there is an intramolecular N-H...N hydrogen bond forming a pseudo-six-membered ring which locks the molecular conformation and eliminates conformational flexibility. The crystal structure is stabilized by O-H...O hydrogen bonds; both molecules in the asymmetric unit form independent chains, each such chain consisting of alternating 'ordered' and 'disordered' molecules in the crystal lattice.

A 100MHz to 1GHz, 0.35V to 1.5V supply 256 x 64 SRAM mock using symmetrized 9T SRAM cell with controlled read

In this paper, we present Dynamic Voltage and Frequency Managed 256 x 64 SRAM block in 65nm technology, for frequency ranging from 100MHz to 1GHz. The total energy is minimized for any operating frequency in the above range and leakage energy is minimized during standby mode. Since noise margin of SRAM cell deteriorates at low voltages, we propose Static Noise Margin improvement circuitry, which symmetrizes the SRAM cell by controlling the body bias of pull down NMOS transistor. We used a 9T SRAM cell that isolates Read and Hold Noise Margin and has less leakage. We have implemented an efficient technique of pushing address decoder into zigzag-super-cut-off in stand-by mode without affecting its performance in active mode of operation. The Read Bit Line (RBL) voltage drop is controlled and pre-charge of bit lines is done only when needed for reducing power wastage.

Adducts of bis(acetylacetonato)zinc(II) with 1,10-phenanthroline and 2,2'-bipyridine

In each of the zinc(II) complexes bis(acetylacetonato-kappa(2)O,O')(1,10-phenanthroline-kappa(2)N,N')zinc(II), [Zn(C(5)H(7)O(2))(2)(C(12)H(8)N(2))], (I), and bis(acetylacetonato-kappa(2)O,O')(2,2'-bipyridine-kappa(2)N,N')zinc(II), [Zn(C(5)H(7)O(2))(2)(C(10)H(8)N(2))], (II), the metal center has a distorted octahedral coordination geometry. Compound (I) has crystallographically imposed twofold symmetry, with Z' = 0.5. The presence of a rigid phenanthroline group precludes intramolecular hydrogen bonding, whereas the rather flexible bipyridyl ligand is twisted to form an intramolecular C-H...O interaction [the chelated bipyridyl ligand is nonplanar, with the pyridyl rings inclined at an angle of 13.4 (1) degrees]. The two metal complexes are linked by dissimilar C-H...O interactions into one-dimensional chains. The present study demonstrates the distinct effects of two commonly used ligands, viz. 1,10-phenanthroline and 2,2'-bipyridine, on the structures of metal complexes and their assembly.

A kinetic analysis of the tumor-associated galactopyranosyl-(1→3)-2-acetamido-2-deoxy-α-d-galactopyranoside antigen—lectin interaction

A kinetic study of the tumor-associated galactopyranosyl-(1→3)-2-acetamido-2-deoxy-α-d-galactopyranoside (T-antigen) with lectin peanut agglutinin is described. The disaccharide antigen was synthesized by chemical methods and was functionalized suitably for immobilization onto a carboxy-methylated sensor chip. The ligand immobilized surface was allowed interaction with the lectin peanut agglutinin, which acted as the analyte and the interaction was studied by the surface plasmon resonance method. The ligand—lectin interaction was characterized by the kinetic on-off rates and a bivalent analyte binding model was found to describe the observed kinetic constants. It was identified that the antigen-lectin interaction had a faster association rate constant (k a1) and a slower dissociation rate constant (k d1) in the initial binding step. The subsequent binding step showed much reduced kinetic rates. The antigen-lectin interaction was compared with the kinetic rates of the interaction of a galactopyranosyl-(1→4)-β-d-galactopyranoside derivative and a mannopyranoside derivative with the lectin.

Apparent shortening of the Csp(3)-Csp(3) bond analysed via a variable-temperature X-ray diffraction study in racemic 1,1 '-binaphthalene-2,2 '-diyl diethyl bis(carbonate)

Crystal structure determination at room temperature [292 (2) K] of racemic 1,1'-binaphthalene-2,2'-diyl diethyl bis(carbonate), C26H22O6, showed that one of the terminal carbon-carbon bond lengths is very short [Csp(3)-Csp(3) = 1.327 (6) angstrom]. The reason for such a short bond length has been analysed by collecting data sets on the same crystal at 393, 150 and 90 K. The values of the corrected bond lengths clearly suggest that the shortening is mainly due to positional disorder at two sites, with minor perturbations arising as a result of thermal vibrations. The positional disorder has been resolved in the analysis of the 90 K data following the changes in the unit-cell parameters for the data sets at 150 and 90 K, which appear to be an artifact of a near centre of symmetry relationship between the two independent molecules in the space group P (1) over bar at these temperatures. Indeed, the unit cell at low temperature (150 and 90 K) is a supercell of the room-temperature unit cell.

Analysis of the MAP/G(a,b)/1/N queue with multiple vacations

This paper deals with a batch service queue and multiple vacations. The system consists of a single server and a waiting room of finite capacity. Arrival of customers follows a Markovian arrival process (MAP). The server is unavailable for occasional intervals of time called vacations, and when it is available, customers are served in batches of maximum size ‘b’ with a minimum threshold value ‘a’. We obtain the queue length distributions at various epochs along with some key performance measures. Finally, some numerical results have been presented.

Unusual Anisotropic Effects from 1,3-Dipolar Cycloadducts of 4-Azidomethyl Coumarins

4-Bromomethylcoumarins (1) reacted with sodium azide in aqueous acetone to give 4-azidomethyl-coumarins (2), which underwent 1,3-dipolar cycloaddition with acetylenic dipolarophiles to give triazoles (3). These triazoles (3) have been found to exhibit interesting variations in the chemical shifts of C-3-H and C-4-methylene protons. Protonation studies indicate that the shielding effect of the C-3-H of coumarin is due to pi-electrons of the triazole ring, further supported by diffraction and computational studies.