1,259 research outputs found
Emission Characteristics and Photostability of N,N'-Bis(2,5-di-tert-butylphenyl)-3,4:9,lO-perylenebis(dicarboximide)
Gas phase clustering of N2 molecules on to TiO+: Comparison with Ti+ and evidence for the octahedral structure of TiO+(N2)5
A striking difference in the clustering efficiency of Ti+ and TiO+ toward N2 or O2 has been observed in a laser vaporizationhigh pressure mass spectrometric source. Evidence for the magic number n=5 within the sequence TiO+(N2) n is presented. The results are consistent with an octahedral structure for TiO+(N2)5
Experimental and theoretical study of benzene (acetonitrile)(n) clusters, n=1-4
Well-resolved spectra of benzeneâacetonitrile binary clustersBAn, with n=1â4 have been obtained by the (one-color) resonant two-photonionization technique using the benzeneâs B2uâA1g 000 and 610 resonances. The spectra reveal a rapid increase in complexity with the number of acetonitrile molecules in the cluster, associated with van der Waal modes and isomeric forms. While only single cluster origins are found for the benzeneâacetonitrile (BA) and the BA2clusters, two and four distinct isomers are identified for the BA3 and BA4clusters, respectively. The origins of the BA and BA2clusters are blueshifted with respect to the free benzene molecule by 38 cmâ1 and 26 cmâ1, respectively. Monte Carlo(MC) simulations reveal two types of isomeric structures of the BAnclusters. The clusters containing an even number of the acetonitrile molecules (BA2, BA4, and BA6) are dominated by acetonitrile anti-parallel paired dimers. The BA3cluster consists of a cyclic acetonitrile trimer parallel to the benzene ring. In the BA5clusters, the acetonitrile molecules are assembled in a cyclic trimerâ+âa paired dimer configuration or in two paired dimersâ+âa single monomer structure. The R2PI spectra, in conjunction with the MC structural models and simple energetic arguments, provide a reasonably compelling picture of the spectroscopic and dynamical phenomena associated with dipole pairing molecular cluster systems
Termolecular proton transfer reactions assisted by ionic hydrogen bond formation: Reactions of aromatic cations with polar molecules
We present a new method that applies resonantâtwoâphoton ionization to generate reactant ions selectively in the source of a highâpressure mass spectrometer (R2PIâHPMS) for kinetic and equilibrium studies. Applications to reactions that would be obscured otherwise in a complex system are illustrated in mixtures of benzene with polar solvent molecules (S). We observe a novel type of proton transferreactions from C6H6 +⢠to two S molecules where S=CH3CN, CH3OH, C2H5OH and CH3COOC2H5, and from C6H5CH3 +⢠to two S molecules where S=CH3OH and C2H5OH to form protonated solvent S2H+ dimers. The reactions are driven by the strong hydrogen bonds in the S2H+ dimers and therefore require the formation of the hydrogen bond concertedly with proton transfer, to make the process energetically feasible. The adducts (C6H6 +â˘)S are observed with blocked solvent molecules where the subsequent switching reaction to yield S2H+ is slow, but not with alcohol reactants that can form hydrogenâbonded chains that facilitate fast subsequent proton extraction. Correspondingly, kinetic simulations suggest that the mechanism proceeds through (C6H6 +â˘)S+SâS2H++C6H5 ⢠and C6H6 +â˘+2SâS2H++C6H5 â˘reactions, respectively. The rate coefficients of these reactions are in the range 10â13â10â12 cm3âsâ1 for the reaction through a bimolecular switching channel and in the range 10â26â10â28 cm6âsâ1 for reaction through a direct termolecular proton extraction mechanism. The relation to energetics and reactant structure is examined
Editorial: Recent breakthroughs in the decoding of circulating nucleic acids and their applications to human diseases
Š 2023 El-Daly, Talaat, Braoudaki, Youness and Cho. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).Peer reviewe
Relevance of PNPLA3, TM6SF2, HSD17B13, and GCKR Variants to MASLD Severity in an Egyptian Population
\ua9 2024 by the authors.Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD), is a frequent clinical condition globally. Single nucleotide polymorphisms (SNPs) associated with NAFLD have been proposed in the literature and based on bioinformatic screening. The association between NAFLD and genetic variants in Egyptians is still unclear. Hence, we sought to investigate the association of some genetic variants with NAFLD in Egyptians. Egyptians have been categorized into either the MASLD group (n = 205) or the healthy control group (n = 187). The severity of hepatic steatosis and liver fibrosis was assessed by a Fibroscan device. TaqMan-based genotyping assays were employed to explore the association of selected SNPs with MASLD. PNPLA3 rs738409 C>G variant is associated with the presence of MASLD with liver fibrosis, the severity of both hepatic steatosis and liver fibrosis, increased systolic and diastolic blood pressure and increased alanine aminotransferase (all p < 0.05), while the TM6SF2 rs58542926 C>T, HSD17B13 rs9992651 G>A, and GCKR rs1260326 T>C variants were not (all p > 0.05). The TM6SF2 rs58542926 T allele is associated with increased fasting blood glucose and a decreased waist circumference. The GCKR rs1260326 C allele is associated with decreased aspartate transaminase and diastolic blood pressure (all p < 0.05). Only after adjusting for the risk factors (age, sex, BMI, WC, HDL, TG, diabetes mellitus, and hypertension) F2 liver fibrosis score is negatively correlated with the HSD17B13 rs9992651 GA genotype. This study offers evidence for the association of the PNPLA3 rs738409 C>G variant with MASLD among Egyptians and for the association of the PNPLA3 rs738409 G allele, the TM6SF2 rs58542926 T allele, and the GCKR rs1260326 C allele with some parameters of cardiometabolic criteria
A Hybrid NLMS/RLS Algorithm to Enhance the Beamforming Process of Smart Antenna Systems
Adaptive beamforming algorithm is a signal processing technique used by smart antenna system to steer the main beam toward the desired signal direction and cancel the interfering signals of other directions. This paper proposes a hybrid non-blind beamforming algorithm that combines the Normalized Least Mean Square (NLMS) algorithm and the Recursive Least Square (RLS) algorithm to exploit the advantages of both algorithms and avoid their drawbacks. The hybrid NLMS/RLS algorithm solves many problems of the other non-blind algorithms. A comparative study between the proposed algorithm and other non-blind beamforming algorithms is introduced to illustrate the points of strength of the proposed algorithm. The hybrid NLMS/RLS algorithm is applied to different types of patch array antenna with resonance frequency 10GHz to demonstrate the performance of the proposed algorithm to each array antenna type
Genetic diversity of hepatitis E virus (HEV) in imported and domestic camels in Saudi Arabia
Camels gained attention since the discovery of MERS-CoV as intermediary hosts for potentially epidemic zoonotic viruses. DcHEV is a novel zoonotic pathogen associated with camel contact. This study aimed to genetically characterize DcHEV in domestic and imported camels in Saudi Arabia. DcHEV was detected by RT-PCR in serum samples, PCR-positive samples were subjected to sequencing and phylogenetic analyses. DcHEV was detected in 1.77% of samples with higher positivity in domestic DCs. All positive imported dromedaries were from Sudan with age declining prevalence. Domestic DcHEV sequences clustered with sequences from Kenya, Somalia, and UAE while imported sequences clustered with one DcHEV isolate from UAE and both sequences clustered away from isolates reported from Pakistan. Full-genome sequences showed 24 amino acid difference with reference sequences. Our results confirm the detection of DcHEV in domestic and imported DCs. Further investigations are needed in human and camel populations to identify DcHEV potential zoonosis threat
Recommended from our members
State of the California current 2012-13: No such thing as an âaverageâ year
This report reviews the state of the California Current System (CCS) between winter 2012 and spring 2013, and includes observations from Washington State to Baja California. During 2012, large-scale climate modes indicated the CCS remained in a cool, productive phase present since 2007. The upwelling season was delayed north of 42°N, but regions to the south, especially 33° to 36°N, experienced average to above average upwelling that persisted throughout the summer. Contrary to the indication of high production suggested by the climate indices, chlorophyll observed from surveys and remote sensing was below average along much of the coast. As well, some members of the forage assemblages along the coast experienced low abundances in 2012 surveys. Specifically, the concentrations of all lifestages observed directly or from egg densities of Pacific sardine, Sardinops sagax, and northern anchovy, Engraulis mordax, were less than previous yearsâ survey estimates. However, 2013 surveys and observations indicate an increase in abundance of northern anchovy. During winter 2011/2012, the increased presence of northern copepod species off northern California was consistent with stronger southward transport. Krill and small-fraction zooplankton abundances, where examined, were generally above average. North of 42°N, salps returned to typical abundances in 2012 after greater observed concentrations in 2010 and 2011. In contrast, salp abundance off central and southern California increased after a period of southward transport during winter 2011/2012. Reproductive success of piscivorous Brandtâs cormorant, Phalacrocorax penicillatus, was reduced while planktivorous Cassinâs auklet, Ptychoramphus aleuticus was elevated. Differences between the productivity of these two seabirds may be related to the available forage assemblage observed in the surveys. California sea lion pups from San Miguel Island were undernourished resulting in a pup mortality event perhaps in response to changes in forage availability. Limited biological data were available for spring 2013, but strong winter upwelling coastwide indicated an early spring transition, with the strong upwelling persisting into early summer
Nonlinear vortex light beams supported and stabilized by dissipation
We describe nonlinear Bessel vortex beams as localized and stationary
solutions with embedded vorticity to the nonlinear Schr\"odinger equation with
a dissipative term that accounts for the multi-photon absorption processes
taking place at high enough powers in common optical media. In these beams,
power and orbital angular momentum are permanently transferred to matter in the
inner, nonlinear rings, at the same time that they are refueled by spiral
inward currents of energy and angular momentum coming from the outer linear
rings, acting as an intrinsic reservoir. Unlike vortex solitons and dissipative
vortex solitons, the existence of these vortex beams does not critically depend
on the precise form of the dispersive nonlinearities, as Kerr self-focusing or
self-defocusing, and do not require a balancing gain. They have been shown to
play a prominent role in "tubular" filamentation experiments with powerful,
vortex-carrying Bessel beams, where they act as attractors in the beam
propagation dynamics. Nonlinear Bessel vortex beams provide indeed a new
solution to the problem of the stable propagation of ring-shaped vortex light
beams in homogeneous self-focusing Kerr media. A stability analysis
demonstrates that there exist nonlinear Bessel vortex beams with single or
multiple vorticity that are stable against azimuthal breakup and collapse, and
that the mechanism that renders these vortexes stable is dissipation. The
stability properties of nonlinear Bessel vortex beams explain the experimental
observations in the tubular filamentation experiments.Comment: Chapter of boo
- âŚ