The crystal and molecular structure of an epoxide,C30H50O

The compound C₃₀H₅₀O (7,8-epoxy-9(87)-abeofriedelane),M _r=376.33, orthorhombic, P2₁2₁2₁,a=11.819(1) Å,b=14.381(2)Å,c=15.402(2)Å,Z=4,D _c=1.083 gm cm^–3,R=0.055, for 1643 reflections (withI>2) out of 1743 unique reflections. The three dimensional structure determination is done to characterize the conformation of this series of compounds which has good promise for drug and for rational understanding of the reaction mechanism in the olefin stereochemistry and the structural basis of synthesis of these natural products.     

Wavelet analysis of cycle-to-cycle pressure variations in an internal combustion engine

Using a continuous wavelet transform we have analyzed the cycle-to-cycle variations of pressure in an internal combustion engine. The time series of maximum pressure variations are examined for different loading and their wavelet power spectrum is calculated for each load. From the wavelet power spectrum we detected the presence of long, intermediate and short-term periodicities in the pressure signal. It is found that depending on the load, the long and intermediate-term periodicities may span several cycles, whereas the short-period oscillations tend to appear intermittently. Knowledge of these periodicities may be useful to develop effective control strategies for efficient combustion.     

Influence of temperature on different optoelectronic characteristics of InGaN light emitting diodes

We have measured the electroluminescence (EL) and carrier lifetime characteristics in InGaN/Sapphire purple light emitting diode (LED), namely, UV3TZ-405-30 in a temperature range from 350 to 120 K and have compared them with those of a similar LED (UV3TZ-395-15) but with different Indium concentration, measured earlier. While it is found that for the present device the EL intensity decreases drastically with lowering of temperature after reaching a maximum (99%) at 228 K, this is markedly different from the previous device where intensity continues to increase monotonically till lowest temperature. This qualitatively distinct temperature dependence indicates difference in nature of localisation of carriers in the multiple quantum wells for varying Indium content in the two devices. The light–current–temperature data have been analysed in terms of the semiconductor rate equations to determine different optoelectronic properties. Next, estimating the ideality factor from the current–voltage (I–V) measurements, the effective carrier lifetime has been evaluated from the open circuit voltage decay process. Using the above measurements, the temperature dependence of the internal quantum efficiency of the device has been calculated and it is found to attain a maximum value of 99.88% at 228 K. Unlike all previous calculations, a unique feature of the present approach has been to include the effect of temperature dependence of the radiative recombination coefficient (B) in the rate equation analysis. Finally, a comparative study of the temperature dependence of the different optoelectronic properties of both devices is presented with and without this effect.     

The absorption,magnetic circular dichroism and emission of Eu2+ in cubic elpasolites

The absorption, magnetic circular dichroism (MCD) and emission/excitation spectra of some $\text{4?}{}^7\text{→4?}{}^6\text{5d}$ transitions in Eu²⁺ in several hexachloro and hexabromoelpasolites have been measured. Data were collected between 5 and 300 K and up to energies of 42,000 cm^?1. The absorption and MCD were satisfactorily interpreted using a coupling scheme that treats the d-electron crystal field as being much greater than the f-electron spin orbit coupling and essentially ignores other interactions.     

Regiospecificity of nucleotide–amino acid mating vs. water dynamics: a key to protein–nucleic acid assemblies: structure of unidecahydrated inosine-5′-monophosphate and L–glutamic acid (2C10H13N4O8P·C5H11NO4·11H2O) cocrystal at atomic resolution

The crystal structure of a unidecahydrated cocomplex between two Inosine-5-monophosphates (IMP) and one L-glutamic acid has been determined by X-ray crystallographic methods. The crystal belongs to the monoclinic space group P2₁ with cell dimensions a = 8.650(1), b = 21.900(1), c = 12.370(1) Å, and = 110.4°(9). This structure reveals extensive hydrogen bonding of glutamic acid to the nucleotide through direct and water-mediated interactions. The phosphate oxygens (O3B and O1B) seem to prefer nonspecific interaction with the functional sites of glutamic acid (OE2 ······O1B = 1.78 Å, NA······O3B = 2.73 Å, OH······O3B = 3.06 Å), whereas the bases prefer specific (O······N3B = 2.88 Å) binding. A solvent mediated N7A···W5···N7B hydrogen bond used for stabilization of the stacked purine bases has been observed as in other amino acid–nucleotide cocrystals. Glutamic acid occupies the same hydrophilic region in the nucleotide cocrystal as was found in glutamine–inosine monophosphate (Gln–IMP) and in serine–inosine monophosphate (Ser–IMP) complexes through substantial replacement of free and bound water molecules. This points to the dynamic hydrogen bonding nature of the water molecules and their stereochemical cooperation for the placement of amino acid through the polycoordination within the crystal.     

Structure of a Cu(II)-containing peptide,diaquo-gly-l-tyr Cu(II) dihydrate, [Cu(C11N2O4H13)(H2O)2·2H2O

The structure of the Cu(II) complex of gly-l-tyr [Cu(C₁₁N₂O₄H₁₃) (H₂O)₂]·2H₂O has been solved by X-ray diffraction methods. The compound crystallizes in the orthorhombic space groupP2₁2₁2₁ witha=11.970(2) Å,b=12.485(2) Å andc=10.418(3) Å, respectively, (MoK)=0.710 Å,D _c =1.59 Mgm^–3,D _m =1.59 Mgm^–3, finalR=0.04. The structure was solved by heavy atom (Cu) phased Fourier and refined by full-matrix least squares methods. The coordination geometry of the ligand around the Cu(II) ion has been established as a distorted tetragonal pyramid. The peptide molecule behaves as a tridentate ligand via its amino (N2), amido (N1) nitrogens and carboxyl (O2) oxygens. The peptide nitrogen is found to be deprotonated.     

Bioconversion of Sodium Dodecyl Sulphate to Rhamnolipid by Pseudomonas aeruginosa: A Novel and Cost-Effective Production Strategy

The utility of rhamnolipids in industry is currently limited due to the high constraints in its economic production. In this scenario, the novel utility of sodium dodecyl sulphate (SDS) as carbon source could serve as promising cost-effective strategy. Screening of effective SDS biodegraders led to the isolation of Pseudomonas aeruginosa S15 capable of concomitant SDS degradation and biosurfactant synthesis. SDS-based rhamnolipid production was proved on SDS minimal agar plates using cetyl trimethylammonium bromide–methylene blue method and optimised in SDS-based minimal salt (SBS) medium. SDS proved to be an ideal carbon source for rhamnolipid synthesis with a high substrate to product conversion rate yielding 6.9 g/l of rhamnolipids from 1 g/l SDS in 5 days. Fast atom bombardment mass spectroscopy analysis of the purified biosurfactant proved the presence of mono- and di-rhamnolipids, viz., Rha-C₁₀-C₁₀, Rha-C₁₀-C₁₂ and Rha-Rha-C₁₀-C₁₀ with surface active properties. The secreted rhamnolipids were not utilised by S15 as a carbon source, but it caused a dispersion of bacterial biofilms in SBS medium. To the best of our knowledge, this is the first report on bioconversion of synthetic detergent to biodetergent. This SDS-based novel methodology presents a more economised mode of rhamnolipid synthesis utilising SDS as sole carbon source.