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91.
Pressurized capillary electrochromatography is a variant of capillary electrochromatography (CEC) in which the driving force is both electroosmotic and hydraulic. The inlet of the CEC capillary is pressurized using an HPLC pump, and an electric field is simultaneously applied. This work describes a method for the analysis of doxorubicin. Doxorubicin was reacted with Cy5.29.OSu in acetonitrile. The derivative was confirmed by RP-TLC. A CEC system equipped with a VDLIF detector was constructed and used to analyze the derivative. The reaction mixture was injected onto a capillary packed in-house with 3 microm C-18 Luna particles and separation was carried out at 25 kV using 70% acetonitrile/ 30% phosphate (10 mM, pH = 4.8) as the mobile phase. The derivatization reaction was optimized by the investigation of parameters such as reaction time, temperature and concentration of label in order to increase the yield of the derivative. The optimal conditions were determined to be 30 min, 80 degrees C and 50 nmol/mL, respectively. Doxorubicin was extracted from plasma using solid-phase extraction under alkaline conditions, derivatized and injected onto the CEC-VDLIF system. The selectivity of the assay was demonstrated by a lack of interfering peaks due to plasma constituents across the elution window of the derivative peak in blank plasma extracts (n = 6 sources). The limit of detection (LOD) of the assay in plasma calculated as 3 s(b)/m was determined to be 1.7 ng/mL. The precision of the assay determined at a concentration of 167.7 ng/mL (n = 5) was found to be within 7.04 %RSD. 相似文献
92.
The effective thermal conductivity of Carbon Nanotube (CNT)-polymer composites has been estimated using analytical and computational models. The analytical approach is based on the Cascade Continuum Micromechanics (CCM) model formulated within the framework of mean-field homogenization and the computational approach is based on numerical homogenization of the composite microstructure using image based Voxel-FEM (Finite Element Method). Comparison of the analytical and computational model predictions with experimental data show that the interfacial thermal resistance is overestimated by the analytical model as a consequence of not taking into account the CNT fiber tortuosity (curviness). (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
93.
Madhu Nagaraj Zahra Najarzadeh Jonathan Pansieri Henrik Biverstl Greta Musteikyte Vytautas Smirnovas Steve Matthews Cecilia Emanuelsson Janne Johansson Joel N. Buxbaum Ludmilla Morozova-Roche Daniel E. Otzen 《Chemical science》2022,13(2):536
Unlike misfolding in neurodegenerative diseases, aggregation of functional amyloids involved in bacterial biofilm, e.g. CsgA (E. coli) and FapC (Pseudomonas), is carefully regulated. However, it is unclear whether functional aggregation is inhibited by chaperones targeting pathological misfolding and if so by what mechanism. Here we analyze how four entirely different human chaperones or protein modulators (transthyretin, S100A9, Bri2 BRICHOS and DNAJB6) and bacterial CsgC affect CsgA and FapC fibrillation. CsgA is more susceptible to inhibition than FapC and the chaperones vary considerably in the efficiency of their inhibition. However, mechanistic analysis reveals that all predominantly target primary nucleation rather than elongation or secondary nucleation, while stoichiometric considerations suggest that DNAJB6 and CsgC target nuclei rather than monomers. Inhibition efficiency broadly scales with the chaperones'' affinity for monomeric CsgA and FapC. The chaperones tend to target the most aggregation-prone regions of CsgA, but do not display such tendencies towards the more complex FapC sequence. Importantly, the most efficient inhibitors (Bri2 BRICHOS and DNAJB6) significantly reduce bacterial biofilm formation. This commonality of chaperone action may reflect the simplicity of functional amyloid formation, driven largely by primary nucleation, as well as the ability of non-bacterial chaperones to deploy their proteostatic capacities across biological kingdoms.Unlike misfolding in neurodegenerative diseases, aggregation of functional amyloids involved in bacterial biofilm, e.g. CsgA (E. coli) and FapC (Pseudomonas), is carefully regulated. 相似文献
94.
Omaish Alqahtani Kiran K. Mirajkar Anil Kumar K R. Mater H. Mahnashi Ibrahim Ahmed Shaikh Susweta Mitra Harshitha Nagaraj Sunil S. More Uday M. Muddapur Aejaz Abdullatif Khan P. Renuka Sudarshan 《Molecules (Basel, Switzerland)》2022,27(21)
Rice is the most important staple food crop feeding more than 50% of the world’s population. Rice blast is the most devastating fungal disease, caused by Magnaporthe oryzae (M. oryzae) which is widespread in rice growing fields causing a significant reduction in the yield. The present study was initiated to evaluate the effect of green synthesized silver nanoparticles (AgNPs) on the biochemical constituents of rice plants infected with blast. AgNPs were synthesized by using Azadirachta indica leaf extract and their characterization was performed using UV-visible spectroscopy, particle size analyser (PSA), scanning electron microscope (SEM), and X-ray diffraction (XRD) which confirmed the presence of crystalline, spherical shaped silver nanoparticles with an average size of 58.9 nm. After 45 days of sowing, artificial inoculation of rice blast disease was performed. After the onset of disease symptoms, the plants were treated with AgNPs with different concentrations. Application of nanoparticles elevated the activity of antioxidative enzymes such as superoxide dismutase, catalase, peroxidase, glutathione reductase, and phenylalanine ammonia-lyase compared to control plants, and total phenol and reducing sugars were also elevated. The outcome of this study showed that an increase in all biochemical constituents was recorded for A. indica silver nanoparticles-treated plants. The highest values were recorded in 30 ppm and 50 ppm AgNPs-treated plants, which showed the highest resistance towards the pathogen. Green synthesized AgNPs can be used in future for disease control in susceptible varieties of rice. The synthesized AgNPs using A. indica leaf extract have shown promising antibacterial activity when tested against 14 multidrug-resistant (MDR) bacteria comprising Gram-negative bacteria Escherichia coli (n = 6) and Klebsiella pneumoniae (n = 7) with a good zone of inhibition diameter, tested with the disc diffusion method. Based on these findings, it appears that A. indica AgNPs have promise as an antibacterial agent effective against MDR pathogens. 相似文献
95.
George Levesque Nagaraj K. Arakere 《International Journal of Solids and Structures》2008,45(25-26):6301-6315
Hybrid silicon nitride ball/steel raceway bearings are used in advanced aircraft engines and space propulsion systems. Silicon nitride is a brittle material and partial cone cracks, or c-cracks, originate from contact interactions during manufacturing. These cracks limit the Rolling Contact Fatigue (RCF) life of the balls. Here the authors examine subsurface Hertzian stresses between contacting spheres, using an analytical stress solution, to investigate their applicability to predicting and characterizing crack size and shape. The authors also incrementally develop these cracks through an iterative crack growth procedure using a 3D finite element analysis. Comparisons are then made to experimental images of the flaws in silicon nitride. By varying the initial conditions during the contact interaction of the balls we demonstrate that a wide range of cone and partial cone cracks, observed in practice, can be generated using both the analytical and numerical fracture mechanics approaches. Furthermore, an expression is presented for the impact velocity that induces a cone crack from a maximum radial stress criterion at the contact periphery. 相似文献
96.
Haruvegowda Kiran Kumar Hemmige S. Yathirajan Nagaraj Manju Balakrishna Kalluraya Ravindranath S. Rathore Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(6):768-776
The reaction of 5‐chloro‐3‐methyl‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehyde with phenols under basic conditions yields the corresponding 5‐aryloxy derivatives; the subsequent reaction of these carbaldehydes with substituted acetophenones yields the corresponding chalcones, which in turn undergo cyclocondensation reactions with hydrazine in the presence of acetic acid to form N‐acetylated reduced bipyrazoles. Structures are reported for three 5‐aryloxycarbaldehydes and the 5‐piperidino analogue, and for two reduced bipyrazole products. 5‐(2‐Chlorophenoxy)‐3‐methyl‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehyde, C17H13ClN2O2, (II), which crystallizes with Z′ = 2 in the space group P, exhibits orientational disorder of the carbaldehyde group in each of the two independent molecules. Each of 3‐methyl‐5‐(4‐nitrophenoxy)‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehyde, C17H13N3O4, (IV), 3‐methyl‐5‐(naphthalen‐2‐yloxy)‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehyde, C21H16N2O2, (V), and 3‐methyl‐1‐phenyl‐5‐(piperidin‐1‐yl)‐1H‐pyrazole‐4‐carbaldehyde, C16H19N3O, (VI), (3RS)‐2‐acetyl‐5‐(4‐azidophenyl)‐5′‐(2‐chlorophenoxy)‐3′‐methyl‐1′‐phenyl‐3,4‐dihydro‐1′H,2H‐[3,4′‐bipyrazole] C27H22ClN7O2, (IX) and (3RS)‐2‐acetyl‐5‐(4‐azidophenyl)‐3′‐methyl‐5′‐(naphthalen‐2‐yloxy)‐1′‐phenyl‐3,4‐dihydro‐1′H,2H‐[3,4′‐bipyrazole] C31H25N7O2, (X), has Z′ = 1, and each is fully ordered. The new compounds have all been fully characterized by analysis, namely IR spectroscopy, 1H and 13C NMR spectroscopy, and mass spectrometry. In each of (II), (V) and (IX), the molecules are linked into ribbons, generated respectively by combinations of C—H…N, C—H…π and C—Cl…π interactions in (II), C—H…O and C—H…π hydrogen bonds in (V), and C—H…N and C—H…O hydrogen bonds in (IX). The molecules of compounds (IV) and (IX) are both linked into sheets, by multiple C—H…O and C—H…π hydrogen bonds in (IV), and by two C—H…π hydrogen bonds in (IX). A single C—H…N hydrogen bond links the molecules of (X) into centrosymmetric dimers. Comparisons are made with the structures of some related compounds. 相似文献
97.
Muthupandi Nagaraj Sithuraj Sathiyamoorthy Muthusamy Boominathan Shanmugam Muthusubramanian Nattamai Bhuvanesh 《Journal of heterocyclic chemistry》2013,50(5):1146-1151
α‐Bromoketones undergo selenium dioxide oxidation to yield reactive 2‐oxo‐2‐arylacetyl bromides that are trapped by aryl‐1,2‐diamines, 1,2‐aminophenol or 1,2‐aminothiophenol to give quinoxalinones, benzoxazinones, and benzothiazinones, respectively, in good yield. 相似文献
98.
Let C be an irreducible smooth complex projective curve, and let E be an algebraic vector bundle of rank r on C. Associated to E, there are vector bundles ${{\mathcal F}_n(E)}$ of rank nr on S n (C), where S n (C) is the n-th symmetric power of C. We prove the following: Let E 1 and E 2 be two semistable vector bundles on C, with genus ${(C)\, \geq\, 2}$ . If ${{\mathcal F}_n(E_1)\,\simeq \, {\mathcal F}_n(E_2)}$ for a fixed n, then ${E_1 \,\simeq\, E_2}$ . 相似文献
99.
100.
Karuppiah Nagaraj Subramanian Sakthinathan Sankaralingam Arunachalam 《Journal of fluorescence》2014,24(2):589-598
A new water-soluble surfactant copper(II) complex [Cu(sal-ala)(phen)(DA)] (sal-ala = salicylalanine, phen = 1,10-phenanthroline, DA = dodecylamine), has been synthesized and characterized by physico-chemical and spectroscopic methods. The critical micelle concentration (CMC) values of this surfactant–copper(II) complex in aqueous solution were obtained from conductance measurements. Specific conductivity data (at 303, 308, 313. 318 and 323 K) served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔG0m, ΔH0m and ΔS0m). The interaction of this complex with nucleic acids (DNA and RNA) has been explored by using electronic absorption spectral titration, competitive binding experiment, cyclic voltammetry, circular dichroism (CD) spectra, and viscosity measurements. Electronic absorption studies have revealed that the complex can bind to nucleic acids by the intercalative binding mode which has been verified by viscosity measurements. The DNA binding constants have also been calculated (Kb?=?1.2?×?105 M?1 for DNA and Kb?=?1.6?×?105 M?1 for RNA). Competitive binding study with ethidium bromide (EB) showed that the complex exhibits the ability to displace the DNA-bound-EB indicating that the complex binds to DNA in strong competition with EB for the intercalative binding site. The presence of hydrophobic ligands, alanine Schiff-base, phenanthroline and long aliphatic chain amine in the complex were responsible for this strong intercalative binding. The surfactant–copper (II) complex was screened for its antibacterial and antifungal activities against various microorganisms. The results were compared with the standard drugs, amikacin(antibacterial) and ketokonazole(antifungal). 相似文献