Intersubband optical absorption in (In,Ga)N/GaN double quantum wells considering applied electric field effects

Journal of Computational Electronics - In the present paper, we theoretically examine the total absorption coefficient related to inter-conduction subband 1S–2P transitions in symmetric...     

Kharasch addition of tetrachloromethane to alkenes catalyzed by metal acetylacetonates

Various transition metal acetylacetonates have proven to be efficient catalytic systems for the Kharasch addition of tetrachloromethane to alkenes under mild conditions, providing 1:1 adducts in up to 87% yield, based on internal standard. The nature of metal, solvent, temperature, olefin/CCl₄ ratio and the presence of nucleophilic co-catalysts were tested to evaluate the scope and limitation of the reaction.     

Spectrofluorometric and Molecular Docking Studies on the Binding of Curcumenol and Curcumenone to Human Serum Albumin

Curcumenol and curcumenone are two major constituents of the plants of medicinally important genus of Curcuma, and often govern the pharmacological effect of these plant extracts. These two compounds, isolated from C. zedoaria rhizomes were studied for their binding to human serum albumin (HSA) using the fluorescence quench titration method. Molecular docking was also performed to get a more detailed insight into their interaction with HSA at the binding site. Additions of these sesquiterpenes to HSA produced significant fluorescence quenching and blue shifts in the emission spectra of HSA. Analysis of the fluorescence data pointed toward moderate binding affinity between the ligands and HSA, with curcumenone showing a relatively higher binding constant (2.46 × 10⁵ M⁻¹) in comparison to curcumenol (1.97 × 10⁴ M⁻¹). Cluster analyses revealed that site I is the preferred binding site for both molecules with a minimum binding energy of −6.77 kcal·mol⁻¹. However, binding of these two molecules to site II cannot be ruled out as the binding energies were found to be −5.72 and −5.74 kcal·mol⁻¹ for curcumenol and curcumenone, respectively. The interactions of both ligands with HSA involved hydrophobic interactions as well as hydrogen bonding.     

Cloning of the cDNA encoding the urotensin II precursor in frog and human reveals intense expression of the urotensin II gene in motoneurons of the spinal cord

Urotensin II (UII) is a cyclic peptide initially isolated from the caudal neurosecretory system of teleost fish. Subsequently, UII has been characterized from a frog brain extract, indicating that a gene encoding a UII precursor is also present in the genome of a tetrapod. Here, we report the characterization of the cDNAs encoding frog and human UII precursors and the localization of the corresponding mRNAs. In both frog and human, the UII sequence is located at the C-terminal position of the precursor. Human UII is composed of only 11 amino acid residues, while fish and frog UII possess 12 and 13 amino acid residues, respectively. The cyclic region of UII, which is responsible for the biological activity of the peptide, has been fully conserved from fish to human. Northern blot and dot blot analysis revealed that UII precursor mRNAs are found predominantly in the frog and human spinal cord. In situ hybridization studies showed that the UII precursor gene is actively expressed in motoneurons. The present study demonstrates that UII, which has long been regarded as a peptide exclusively produced by the urophysis of teleost fish, is actually present in the brain of amphibians and mammals. The fact that evolutionary pressure has acted to conserve fully the biologically active sequence of UII suggests that the peptide may exert important physiological functions in humans.     

Co-overexpression of the malate dehydrogenase (Mdh) and the malic enzyme A (MaeA) in several Escherichia coli mutant backgrounds increases malate redirection towards hydrogen production

The combustion of fossil fuels is leading to global warming due to the emissions of greenhouse gases. Hydrogen (H₂) is a clean and sustainable energy source and a promising alternative to fossil fuels. The bacteria Escherichia coli naturally produces H₂, and it has been widely modified by metabolic engineering to enhance this production. Malate plays an important role in H₂ synthesis when glycerol is used as a C source. In this work, C-flux was more efficiently redirected from malate to H₂ by the P_BAD promoter-controlled co-overexpression of the malate dehydrogenase and the malic enzyme MaeA in the dcuD and frdCdcuD mutants. These mutants previously have been reported as improved producing strains, but by using this strategy, H₂ production increased 36 and 24%, respectively. The overexpression of both enzymes is essential, although MaeA expression was higher than Mdh, using the pBAD promoter, which was more appropriate than the pTrc99a one.     

Updated band model parameters for H2O,CO2, CH4 and CO radiation at high temperature

Statistical narrow-band (SNB) model parameters for H₂O, CO₂, CH₄ and CO, and correlated-k (CK) parameters for H₂O and CO₂ are generated from line by line calculations and recently improved spectroscopic databases in wide temperature and spectral ranges. Results from the new parameters are compared to direct line by line calculations and to results from earlier model parameters [A. Soufiani, J. Taine, High temperature gas radiative property parameters of statistical narrow-band model for H₂O, CO₂ and CO and correlated-k (ck) model for H₂O and CO₂, Int. J. Heat Mass Transfer 40 (1997) 987–991] in terms of band averaged spectral transmissivities, Planck mean absorption coefficients, and total emissivities. The comparisons show first a good agreement between updated SNB, CK and LBL results. Significant improvements on earlier parameters are observed for H₂O and CO₂, especially at very high temperatures and path lengths. Model parameters and computer programs illustrating their implementation are provided as Supplementary data.     

Identification of a novel secretogranin II-derived peptide (SgII(187-252)) in adult and fetal human adrenal glands using antibodies raised against the human recombinant peptide

Molecular cloning of secretogranin II (SgII) in phylogenetically distant species has recently revealed the existence of a highly conserved 66-amino acid peptide flanked by preserved pairs of basic residues. This observation suggested that this peptide, named EM66, which had not been described to date, could be an important processing product of SgII. The aim of the present study was to investigate the possible occurrence of EM66 in the human adrenal gland. The EM66 peptide was generated in Escherichia coli, which was programmed to make a fusion protein containing the human EM66 sequence. The affinity-purified fusion protein was used to raise polyclonal antibodies in rabbits. The free EM66 peptide was obtained by cleavage of the fusion protein followed by high performance liquid chromatography purification. Immunohistochemical analysis using the EM66 antibodies revealed intense labeling of adrenochromaffin cells in the adult adrenal medulla and the fetal adrenal gland. A sensitive and specific RIA was developed and applied to the detection of EM66-like immunoreactivity in extracts of adult adrenal medulla and whole fetal adrenal gland after high performance liquid chromatographic analysis. A major immunoreactive species exhibiting the same retention time as recombinant EM66 was detected in both adult and fetal adrenal extracts. Taken together, these data demonstrate that posttranslational processing of SgII actually generates EM66 in the adrenal gland. The strong conservation of the amino acid sequence of EM66 in the vertebrate phylum and the occurrence of the mature peptide in both fetal and adult chromaffin cells suggest that EM66 could play an important physiological role in the human adrenal gland.     

An incremental elastic-plastic Finite Element solver in a workstation cluster environment Part I. Formulations and parallel processing

We discuss solution schemes for the incremental elastic-plastic structural problem, discretized by means of the Finite Element method. Attention is focused on their formulation and implementation in a parallel computing environment defined by a cluster of workstations connected by means of a network. The availability of parallel computers allows one to consider possible formulations and solution strategies so far not considered competitive with the classical Newton-like schemes implying the definition of an elastic-plastic tangent stiffness matrix. The solution strategies herein considered are based on the explicit integration of the actual elastic-plastic rate problem. This, in turn, is phrased in terms of two different formulations, whose relative advantages—particularly with respect to their integration in parallel—are discussed. A − gl (displacemen plastic multiplier) formulation of the structural rate theory of plasticity [1], integrated by means of an explicit, element-by-element scheme, seems to be the most promising one.     

Preparation and characterization of poly(ether ether ketone)/poly(ether imide) [PEEK/PEI] blends for fused filament fabrication

Journal of Materials Science - The present study focuses on the preparation and characterization of a poly(ether ether ketone)/poly(ether imide) [PEEK/PEI] blend for application in additive...