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621.
Asymmetric flow field flow fractionation (AsFlFFF) was combined with pyrolysis-gas chromatography mass spectrometry for a sized based fractionation and a detailed compositional study of the triglycerides and cholesterol associated with the various lipoprotein subclasses present in human serum. Serum samples were injected in the AsFlFFF instrument and fractionated with a time-delayed exponential decay cross flow program. The fractions collected after AsFlFFF elution were injected into a programmable temperature vaporizer (PTV) GC-injector, containing a fritted liner. A temperature and split-flow program for the PTV injector was optimized for the thermally assisted hydrolysis and methylation of the compounds of interest. The resulting fatty acid and cholesterol methyl esters were separated by GC and characteristic fragment ions were detected by MS. The system was optimized and calibrated with triglyceride and cholesterol standards for quantitative analysis. The possible interference by phospholipids with the quantitative results was investigated and found to be of minor importance.The concentrations and lipoprotein profiles of triglycerides and cholesterol were determined in a pooled serum sample of healthy volunteers and a serum sample of a sepsis patient. The results obtained with the GC–MS approach were compared with those of a previously developed method based on AsFlFFF with a dual enzymatic reaction detection system. A good agreement of the profiles was found, for cholesterol as well as for the triglycerides, even when the GC–MS method quantifies the fatty acids while with the enzymatic reaction method the glycerol concentrations are determined. Total cholesterol and triglyceride concentration values for the serum samples showed good agreement with the results of the standard enzymatic method as used in practice in the university hospital. 相似文献
622.
Magnetic properties of superconducting yttrium barium copper oxide (YBa2Cu3O7-δ) nanoparticles (31–43 nm) prepared by a chemical route have been studied. These nanoparticles have been found to clearly
exhibit ferromagnetism at room temperature while superconducting transition is observed at lower temperatures. The low temperature
hysteresis loops show evidence suggesting the presence of a large paramagnetic contribution in addition to the superconducting
contributions from the particles. Bulk YBCO obtained by pelletizing and heating the same nanoparticles at a high temperature,
displays the usual superconducting characteristics and gives no trace of ferromagnetism down to 10 K. The superconducting
transition temperature of the nanoparticles is lower than for the bulk YBCO and there is a trend of decreasing T
c with smaller size of the particles. In contrast the ferromagnetic moment increases with decreasing particle size. The development
of ferromagnetism is attributed to the presence of surface oxygen vacancies that lead to electron redistribution on the different
ions at the surface. The simultaneous decrease of superconducting T
c and the increase of ferromagnetism with decreasing size considered as being reflective of the increased role of finite size
and surface defects that weaken the superconductivity and enhance the ferromagnetism. Possible coexistence of surface ferromagnetism
and bulk superconductivity at lower temperatures is discussed. 相似文献
623.
Molecular Diversity - Machine learning (ML) methods have attracted increasing interest in chemistry as in all fields of science in recent years. This method is of great importance for the design of... 相似文献
624.
Ab-initio calculations are performed to investigate the structural, electronic and magnetic properties of spin-polarized diluted magnetic semiconductors composed of II-VI compounds Cd1−xCoxX (X=S, Se, Te) at x=0.25. From the calculated results of band structure and density of states, the half-metallic character and stability of ferromagnetic state for Cd1−xCoxS, Cd1−xCoxSe and Cd1−xCoxTe alloys are determined. It is found that the tetrahedral crystal field gives rise to triple degeneracy t2g and double degeneracy eg. Furthermore, we predict the values of spin-exchange splitting energies Δx(d) and Δx(p−d) and exchange constants N0α and N0β produced by the Co 3d states. Calculated total magnetic moments and the robustness of half-metallicity of Cd1−xCoxX (X=S, Se, Te) with respect to the variation in lattice parameters are also discussed. We also extend our calculations to x=0.50, 0.75 for S compounds in order to observe the change due to increase in Co. 相似文献
625.
Ajay Kumar Sandeep Kaur Sukhvinder Dhiman Prithvi Pal Singh Gaurav Bhatia Sharad Thakur Hardeep Singh Tuli Upendra Sharma Subodh Kumar Abdulmajeed G. Almutary Abdullah M. Alnuqaydan Arif Hussain Shafiul Haque Kuldeep Dhama Satwinderjeet Kaur 《Molecules (Basel, Switzerland)》2022,27(11)
Onosma bracteata Wall. is an important medicinal and immunity-enhancing herbs. This plant is commonly used in the preparation of traditional Ayurvedic drugs to treat numerous diseases. Inspired by the medicinal properties of this plant, the present study aimed to investigate the antiproliferative potential and the primary molecular mechanisms of the apoptotic induction against human osteosarcoma (MG-63) cells. Among all the fractions isolated from O. bracteata, ethyl acetate fraction (Obea) showed good antioxidant activity in superoxide radical scavenging assay and lipid peroxidation assay with an EC50 value of 95.12 and 80.67 µg/mL, respectively. Silica gel column chromatography of ethyl acetate (Obea) fraction of O. bracteata yielded a pure compound, which was characterized by NMR, FTIR, and HR-MS analysis and was identified as 1,2-benzene dicarboxylic acid, bis (2-methyl propyl) ester (BDCe fraction). BDCe fraction was evaluated for the antiproliferative potential against human osteosarcoma MG-63, human neuroblastoma IMR-32, and human lung carcinoma A549 cell lines by MTT assay and exhibited GI50 values of 37.53 μM, 56.05 μM, and 47.12 μM, respectively. In MG-63 cells, the BDCe fraction increased the level of ROS and simultaneously decreased the mitochondria membrane potential (MMP) potential by arresting cells at the G0/G1 phase, suggesting the initiation of apoptosis. Western blotting analysis revealed the upregulation of p53, caspase3, and caspase9 while the expressions of p-NF-κB, p-Akt and Bcl-xl were decreased. RT-qPCR studies also showed upregulation in the expression of p53 and caspase3 and downregulation in the expression of CDK2, Bcl-2 and Cyclin E genes. Molecular docking analysis displayed the interaction between BDCe fraction with p53 (−151.13 kcal/mol) and CDK1 (−133.96 kcal/mol). The results of the present work suggest that the BDCe fraction has chemopreventive properties against osteosarcoma (MG-63) cells through the induction of cell cycle arrest and apoptosis via Akt/NF-κB/p53 pathways. This study contributes to the understanding of the utilization of BDCe fraction in osteosarcoma treatment. 相似文献
626.
Muhammad Arif Rahim Ullah Maaz Ahmad Ahmad Ali Zahid Ullah Mohammad Ali Fakhria A. Al-Joufi Muhammad Zahoor Hassan Sher 《Molecules (Basel, Switzerland)》2022,27(11)
Biologically synthesized silver nanoparticles are emerging as attractive alternatives to chemical pesticides due to the ease of their synthesis, safety and antimicrobial activities in lower possible concentrations. In the present study, we have synthesized silver nanoparticles (AgNPs) using the aqueous extract of the medicinal plant Euphorbia wallichii and tested them against the plant pathogenic bacterium Xanthomonas axonopodis, the causative agent of citrus canker, via an in vitro experiment. The synthesized silver nanoparticles were characterized by techniques such as UV-Vis spectroscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis and transmission electron microscopy. Moreover, the plant species were investigated for phenolics, flavonoids and antioxidant activity. The antioxidant potential of the extract was determined against a DPPH radical. The extract was also evaluated for phenolic compounds using the HPLC technique. The results confirmed the synthesis of centered cubic, spherical-shaped and crystalline nanoparticles by employing standard characterization techniques. A qualitative and quantitative phytochemical analysis revealed the presence of phenolics (41.52 mg GAE/g), flavonoids (14.2 mg QE/g) and other metabolites of medicinal importance. Different concentrations (1000 µg/mL to 15.62 µg/mL—2 fold dilutions) of AgNPs and plant extract (PE) alone, and both in combination (AgNPs-PE), exhibited a differential inhibition of X. axanopodis in a high throughput antibacterial assay. Overall, AgNPs-PE was superior in terms of displaying significant antibacterial activity, followed by AgNPs alone. An appreciable antioxidant potential was recorded as well. The observed antibacterial and antioxidant potential may be attributed to eight phenolic compounds identified in the extract. The Euphorbia wallichii leaf-extract-induced synthesized AgNPs exhibited strong antibacterial activity against X. axanopodis, which could be exploited as effective alternative preparations against citrus canker in planta in a controlled environment. In addition, as a good source of phenolic compounds, the plant could be further exploited for potent antioxidants. 相似文献
627.
Sehrish Nazir Shri Prakash Pandey Famiza Abdul Latif Pramod K. Singh 《Macromolecular Symposia》2024,413(1):2300035
Solid polymer electrolyte (SPE) films based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF–HFP) with salt and ionic-liquid (IL) are synthesized using the solution-cast technique and summarized in this review. Doping ILs or salts increases ionic conductivity up to the device level. This is further confirmed using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) measurements. Polarized optical microscopy (POM) affirms that enhancement in ionic conductivity is due to increase in amorphous nature of film. The complex nature of polymer electrolyte films is confirmed using Fourier transform infrared (FT-IR) spectroscopy. Overall results show that doping IL into polyether matrix is advantageous material playing a dominant role in electrochemical devices. 相似文献
628.
Arif Akhundov Dima Bardin Lida Kalinovskaya Tord Riemnann 《Fortschritte der Physik》1996,44(5):373-482
We give an exhaustive presentation of the semi-analytical approach to the model independent leptonic QED corrections to deep inelastic neutral current lepton-nucleon scattering. These corrections include photonic bremsstrahlung from and vertex corrections to the lepton current of the order φ(α) with soft photon exponentiation. A common treatment of these radiative corrections in several variables — leptonic, hadronic, mixed, Jaquet-Blondel variables — has been developed and double differential cross sections are calculated. In all sets of variables we use some structure functions, which depend on the hadronic variables and which do not have to be defined in the quark parton model. The remaining numerical integrations are twofold (for leptonic variables) or onefold (for all other variables). For the case of hadronic variables, all phase space integrals have been performed analytically. Numerical results are presented for a large kinematical range, covering fixed target as well as collider experiments at HERA or LEP⊗LHC, with a special emphasis on HERA physics. 相似文献
629.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
630.
Atta M. Arif Alan H. Cowley Robert M. Kren Donald L. Westmoreland 《Heteroatom Chemistry》1990,1(1):117-122
The phosphenium ion [(i-Pr2N)CIP]+ (1) reacts with crotonaldehyde dimethylhydrazone (2) to afford a product with a C3NP ring system (4) . The reaction of 1 with acetone azine (3) results in a novel tricyclic compound (6) which features a C2N2P2 and two C2N2P rings. The structures of 4 and 6 were established by X-ray crystallography. Compound 4 , C12H26AlCl3N3OP, crystallizes in the monoclinic space group P21/n with Z = 4, a = 15.400(6), b = 14.442(4), c = 9.206(3) Å, and β = 93.33(3)°. Compound 6 , C12H22Al2Cl6N4O2P2, crystallizes in the triclinic group P1 with Z = 1, a = 8.556(1), b = 9.782(1), c = 8.119(1) Å, α = 94.48(1), β = 104.97(1), and γ = 78.35(1)°. 相似文献