排序方式: 共有193条查询结果,搜索用时 15 毫秒
31.
Khalifa S. Al-Khalifa Rasha AlSheikh Moahmmed T. Al-Hariri Hosam El-Sayyad Maher S. Alqurashi Saqib Ali Amr S. Bugshan 《Molecules (Basel, Switzerland)》2021,26(21)
This study aimed to evaluate the antimicrobial effect of Thymoquinone (TQ) on four different oral microorganisms. Minimum Bactericidal Concentration (MBC), Minimum Inhibition Concentration (MIC), Broth microdilution, and Well diffusion tests were used to determine the optimum antimicrobial concentrations of TQ against Streptococcus salivarius, Streptococcus oralis, Streptococcus mutans, and Staphylococcus aureus over 1, 3, 6, 12 and 24 h. Chlorhexidine 0.12% was selected as a positive control. The inhibitory effect of TQ on bacterial growth was most noticeable with S. salivarius, while the least affected was S. aureus. TQ’s MBC and MIC for S. oralis and S. aureus were comparable 2 mg/mL and 3 mg/mL, respectively. S. salivarius was most resistant to TQ and displayed a value of 5 mg/mL and 4 mg/mL for MIC and MBC, respectively. The viable count of different strains after exposure to TQ’s MBC values was most noticeable with S. aureus followed by S. oralis and S. mutans, while S. salivarius was least affected. This study emphasized the promising antimicrobial effect of TQ against the four main oral microorganisms. It has a potential preventive effect against dental caries as well as other oral diseases. 相似文献
32.
Examining metal nanoparticle surface chemistry using hollow-core, photonic-crystal, fiber-assisted SERS 总被引:1,自引:0,他引:1
In this Letter, we demonstrate the efficacy of hollow core photonic crystal fibers (HCPCFs) as a surface-enhanced Raman spectroscopy (SERS) platform for investigating the ligand exchange process on the surface of gold nanoparticles. Raman measurements carried out using this platform show the capability to monitor minute amounts of surface ligands on gold nanoparticles used as an SERS substrate. The SERS signal from an HCPCF exhibits a tenfold enhancement compared to that in a direct sampling scheme using a cuvette. Using exchange of cytotoxic cetyltrimethylammonium bromide with α-methoxy-ω-mercaptopoly(ethylene glycol) on the surface of gold nanorods as an exemplary system, we show the feasibility of using HCPCF SERS to monitor the change in surface chemistry of nanoparticles. 相似文献
33.
M.S. Attia A.O. Youssef Amr A. Essawy M.S.A. Abdel-Mottaleb 《Journal of luminescence》2012,132(10):2741-2746
Highly luminescent complexes of Eu and Tb ions with norfloxacin (NFLX) and gatifloxacin (GFLX) were prepared in sol–gel matrix. The red and green emissions of Eu and Tb ions were obtained by the energy transfer from the triplet state of (NFLX) and (GFLX) to the excited emitting states (5D0 and 5D4) of Eu and Tb, respectively. The intensity of the electric field emission bands (5D0→7F2, 617 nm and 5D4→7F5, 545 nm) of Eu and Tb ions were proportional to the concentration of (NFLX at pH 6.0) and (GFLX at pH 3.5) in acetonitrile with excitation wavelengths (λex) (340 and 395) and (370 and 350 nm) for Eu and Tb ions, respectively. The monitored luminescence intensity of the system showed a good linear relationship with the concentration of NFLX within a range of 5×10?9–5.8×10?6 and 5×10?8–1.0×10?6 mol L?1 with a correlation coefficient of 0.990, and for GFLX within a range of 2.4×10?9–3.2×10?5 and 5×10?8–8.0×10?6 mol L?1 with a correlation coefficient of 0.995. The detection limit (LOD) was determined as 3.0×10?9 and 1.0×10?8 mol L?1 for NFLX and 1.6×10?10 and 2.0×10?8mol L?1 for GFLX. The limit of quantification (LOQ) is 9×10?9 and 3.0×10?8 and 4.8×10?10 and 6.0×10?8 in case of Eu and Tb, respectively. 相似文献
34.
Two methods for the preparation of uniform dispersions of dehydrocholic acid of different morphologies are described. In the first case, the drug was dissolved in acetone and then re-precipitated by adding a non-solvent (either water or an aqueous stabilizer solution), which yielded rod-like particles. In the second procedure, spheres, consisting of small elongated subunits, were obtained by acidification of basic aqueous solutions of the drug. The resulting particles were characterized in terms of their structure and surface charge characteristics. 相似文献
35.
Qinjun Kang Peter C. Lichtner Hari S. Viswanathan Amr I. Abdel-Fattah 《Transport in Porous Media》2010,82(1):197-213
We apply a multi-component reactive transport lattice Boltzmann model developed in previous studies for modeling the injection
of a CO2-saturated brine into various porous media structures at temperatures T = 25 and 80°C. In the various cases considered the porous medium consists initially of calcite with varying grain size and
shape. A chemical system consisting of Na+, Ca2+, Mg2+, H+, CO2°(aq){{\rm CO}_2^{\circ}{\rm (aq)}}, and Cl− is considered. Flow and transport by advection and diffusion of aqueous species, combined with homogeneous reactions occurring
in the bulk fluid, as well as the dissolution of calcite and precipitation of dolomite are simulated at the pore scale. The
effects of the structure of the porous media on reactive transport are investigated. The results are compared with a continuum-scale
model and the discrepancies between the pore- and continuum-scale models are discussed. This study sheds some light on the
fundamental physics occurring at the pore scale for reactive transport involved in geologic CO2 sequestration. 相似文献
36.
[(p‐Sulfonamidophenyl)azo]malononitrile ( 1a,b ) reacted with N‐cyclohexanemethylidene‐2‐cyanoacetohydrazide, N'‐arylmethylidene‐2‐cyanoacetohydrazide ( 3a‐c ), S‐methylthiourea and hydrazine hydrate to afford [1,2,4]triazolo‐[1,5‐a]pyridinone derivatives ( 2a,b ) & ( 4a‐c ), substituted pyrimidines 5a,b and 6a,b. The corresponding pyridazinones 7a,b were synthesized from the reaction of 1c,d with ethyl cyanoacetate. Compound 7a,b reacted with elemental sulfur to yield 8a,b . Compound 6a underwent cycloaddition with α‐cinnamonitrile 9a‐e to yield 11a‐c, 14 and 15 . Also, compound 6a reacted with β‐ketoester and 1,3‐diketones to give 16, 17 and 18 . 相似文献
37.
Katren F. Khella Ahmed I. Abd El Maksoud Amr Hassan Shaimaa E. Abdel-Ghany Rafaat M. Elsanhoty Mohammed Abdullah Aladhadh Mohamed A. Abdel-Hakeem 《Molecules (Basel, Switzerland)》2022,27(13)
Carnosic acid (CA) is a natural phenolic compound with several biomedical actions. This work was performed to study the use of CA-loaded polymeric nanoparticles to improve the antitumor activity of breast cancer cells (MCF-7) and colon cancer cells (Caco-2). CA was encapsulated in bovine serum albumin (BSA), chitosan (CH), and cellulose (CL) nanoparticles. The CA-loaded BSA nanoparticles (CA-BSA-NPs) revealed the most promising formula as it showed good loading capacity and the best release rate profile as the drug reached 80% after 10 h. The physicochemical characterization of the CA-BSA-NPs and empty carrier (BSA-NPs) was performed by the particle size distribution analysis, transmission electron microscopy (TEM), and zeta potential. The antitumor activity of the CA-BSA-NPs was evaluated by measuring cell viability, apoptosis rate, and gene expression of GCLC, COX-2, and BCL-2 in MCF-7 and Caco-2. The cytotoxicity assay (MTT) showed elevated antitumor activity of CA-BSA-NPs against MCF-7 and Caco-2 compared to free CA and BSA-NPs. Moreover, apoptosis test data showed an arrest of the Caco-2 cells at G2/M (10.84%) and the MCF-7 cells at G2/M (4.73%) in the CA-BSA-NPs treatment. RT-PCR-based gene expression analysis showed an upregulation of the GCLC gene and downregulation of the BCL-2 and COX-2 genes in cells treated with CA-BSA-NPs compared to untreated cells. In conclusion, CA-BSA-NPs has been introduced as a promising formula for treating breast and colorectal cancer. 相似文献
38.
Sallam H. A. Abdel-Mageid R. E. Amr A. E. 《Russian Journal of General Chemistry》2019,89(11):2308-2313
Russian Journal of General Chemistry - In the current study, a series of macrocyclic tripeptide Schiff bases 2–6 were synthesized by using macrocyclic tripeptide hydrazide 1 as starting... 相似文献
39.
Raluca Anamaria Şeptelean Amr A. A. Attia Alexandru Lupan R. Bruce King 《International journal of quantum chemistry》2019,119(9):e25880
The lowest energy structures for all of the eight-vertex [M]CB6H7 {[M] = CpFe, CpRu. Co(CO)2, Rh(CO)2, (Me3P)2Fe(H), (Me3P)2Ru(H)}, [M]C2B5H7 {[M] = CpMn, CpRe, Cr(CO)3, Mo(CO)3}, and [M]2C2B4H6 ([M] = CpFe, CpRu) systems having 16 skeletal electrons were found by density functional theory to be capped pentagonal bipyramids providing a degree 6 vertex for a metal atom. Thus the capped pentagonal bipyramid plays a similar role for eight-vertex metallaboranes with 16 skeletal electrons as the isocloso deltahedra play in 9- and 10-vertex metallaboranes with 18 and 20 skeletal electrons, respectively. Furthermore, in all of these metallaborane systems the closo bisdisphenoidal structures were always found to be higher energy structures than their capped pentagonal bipyramidal isomers. For the bimetallic systems Cp2M2C2B4H6 (M = Fe, Ru) even higher energy hexagonal bipyramid structures with degree 6 vertices for both metal atoms were also found. 相似文献
40.
A novel approach for characterizing protein ligand complexes: molecular basis for specificity of small-molecule Bcl-2 inhibitors 总被引:5,自引:0,他引:5
Lugovskoy AA Degterev AI Fahmy AF Zhou P Gross JD Yuan J Wagner G 《Journal of the American Chemical Society》2002,124(7):1234-1240
The increasing diversity of small molecule libraries has been an important source for the development of new drugs and, more recently, for unraveling the mechanisms of cellular events-a process termed chemical genetics.(1) Unfortunately, the majority of currently available compounds are mechanism-based enzyme inhibitors, whereas most of cellular activity regulation proceeds on the level of protein-protein interactions. Hence, the development of small molecule inhibitors of protein-protein interactions is important. When screening compound libraries, low-micromolar inhibitors of protein interactions can be routinely found. The enhancement of affinities and rationalization of the binding mechanism require structural information about the protein-ligand complexes. Crystallization of low-affinity complexes is difficult, and their NMR analysis suffers from exchange broadening, which limits the number of obtainable intermolecular constraints. Here we present a novel method of ligand validation and optimization, which is based on the combination of structural and computational approaches. We successfully used this method to analyze the basis for structure-activity relationships of previously selected (2) small molecule inhibitors of the antiapoptotic protein Bcl-xL and identified new members of this inhibitor family. 相似文献