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261.
262.
263.
Hui‐Bog Noh Pankaj Kumar Tapan Kumar Biswas Duk‐Soo Kim Yoon‐Bo Shim 《Electroanalysis》2010,22(6):632-638
The performance of an enzyme sensor fabricated through covalent bond formation on the HRP‐bonded poly(1,8‐diaminonaphthalene) (polyDAN) layer with gold nanoparticles (AuNPs) was applied to catalyze the electrochemical reduction of H2O2. The surface characteristics of the sensor probe were studied using cyclic voltammetry, SEM, XPS, QCM, and impedance spectroscopy. The AuNP‐deposited surface resulted in higher conductivity and sensitivity for H2O2 detection in phosphate buffer solution. A linear calibration plot was obtained in the H2O2 concentration range between 10.0 μM and 25.0 mM with detection limit 5.0±1.25 μM. The lifetime of HRP/polyDAN/AuNP/GC probe was over 70 days without response loss. 相似文献
264.
2-Methylprop-2-ene-, prop-2-ene-, 1-methylprop-2-ene-, and (E)-but-2-enesulfonyl chlorides have been used as electrophilic partners in desulfinylative palladium-catalyzed C-C coupling with Grignard reagents and sodium salts of dimethyl malonate and methyl acetoacetate. Neopentyl alk-2-ene sulfonates can also be used as electrophilic partners in desulfinylative allylic arylations and allylic alkylations. The regioselectivity of the allylic arylation and alkylation depends on the nature of the catalyst. With PdCl2(PhCN)2, (E)-crotyl derivatives are formed in high regioselectivity using either 1-methylprop-2-ene- or (E)-but-2-enesulfonyl chloride. 相似文献
265.
Syntheses, characterizations, electrochemistry and catalytic properties for styrene epoxidation of three manganese(III) compounds [MnIIIL1(H2O)(MeOH)](ClO4) (1) [MnIIIL1(N3)(H2O)]·dmf (2) [MnIIIL1(Cl)(H2O)] (3) derived from the Schiff base compartmental ligand N,N′-o-phenylenebis(3-ethoxysalicylaldimine) (H2L1) are reported. The three compounds are characterized by elemental analyses, IR, mass and UV–Vis spectra and conductance values. Single crystal X-ray structures of 1 and 2 have been determined. The structures of 1 and 2 show that these are mononuclear compounds having a salen type structure. In both structures, a dinuclear species is formed by bifurcated hydrogen bonding involving coordinated water molecule. The coordination of chloride in 3 is shown by conductance measurements. The compounds have also been characterized by UV–Vis and mass spectroscopic studies. Cyclic voltammetric and square wave voltammetric studies of the three compounds reveal that these undergo Mn(III)/Mn(II) reduction reversibly with the order of the ease of reduction as 3 > 2 > 1. This order has been explained proposing the composition of active species in solution. Catalytic properties for epoxidation of styrene by all the three complexes using PhIO and NaOCl as oxidant have been studied. The order of both the styrene conversion and styrene epoxidation using the three title compounds is 3 > 1 > 2. Again, it has been observed that more efficient conversion and epoxidation take place when PhIO is used as oxidant. 相似文献
266.
Maria A. Mendoza DeEtta K. Mills Hemant Lata Suman Chandra Mahmoud A. ElSohly Jose R. Almirall 《Analytical and bioanalytical chemistry》2009,393(2):719-726
Cannabis sativa is the most frequently used of all illicit drugs in the USA. Cannabis has been used throughout history for its stems in the
production of hemp fiber, seed for oil and food, and buds and leaves as a psychoactive drug. Short tandem repeats (STRs) were
chosen as molecular markers owing to their distinct advantages over other genetic methods. STRs are codominant, can be standardized
such that reproducibility between laboratories can be easily achieved, have a high discrimination power, and can be multiplexed.
In this study, six STR markers previously described for C. sativa were multiplexed into one reaction. The multiplex reaction was able to individualize 98 cannabis samples (14 hemp and 84 marijuana, authenticated as originating from 33 of the 50 states of the USA) and detect
29 alleles averaging 4.8 alleles per loci. The data did not relate the samples from the same state to each other. This is
the first study to report a single-reaction sixplex and apply it to the analysis of almost 100 cannabis samples of known geographic
origin.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
267.
Arindam Sarkar Paltu Banerjee Sk. Ugir Hossain Sudin Bhattacharya Subhash Chandra Bhattacharya 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,72(5):1097-1102
In this work, three newly synthesized derivatives of thiazolidinediones, with potential for application as drugs in pharmaceutical industry and free radical scavenging activity, have been taken up to investigate their behaviour in different homogeneous solvents. The purpose of this work is to study the solvation characteristics in ground and excited states of the derivatives by monitoring the absorbance and fluorescence band maxima. The steady state and time resolved fluorescence studies in protic and aprotic solvents have been rationalized on the basis of solute–solvent interaction and substituent effect on these photophysical processes have been analyzed. Substituents at different positions of the aryl moiety affect the hydrogen bond formation ability of the probes. 相似文献
268.
Rabindra N. Roy Lakshmi N. Roy Shahaf Ashkenazi Joshua T. Wollen Craig D. Dunseth Michael S. Fuge Jared L. Durden Chandra N. Roy Hannah M. Hughes Brett T. Morris Kevin L. Cline 《Journal of solution chemistry》2009,38(4):449-458
The values of the second dissociation constant, pK
2, of N-(2-hydroxyethyl) piperazine-N′-2-ethanesulfonic acid (HEPES) have been reported at twelve temperatures over the temperature range 5 to 55 °C, including
37 °C. This paper reports the results for the pa
H of eight isotonic saline buffer solutions with an I=0.16 mol⋅kg−1 including compositions: (a) HEPES (0.01 mol⋅kg−1) + NaHEPES (0.01 mol⋅kg−1) + NaCl (0.15 mol⋅kg−1); (b) HEPES (0.02 mol⋅kg−1) + NaHEPES (0.02 mol⋅kg−1) + NaCl (0.14 mol⋅kg−1); (c) HEPES (0.03 mol⋅kg−1) + NaHEPES (0.03 mol⋅kg−1) + NaCl (0.13 mol⋅kg−1); (d) HEPES (0.04 mol⋅kg−1) + NaHEPES (0.04 mol⋅kg−1) + NaCl (0.12 mol⋅kg−1); (e) HEPES (0.05 mol⋅kg−1) + NaHEPES (0.05 mol⋅kg−1) + NaCl (0.11 mol⋅kg−1); (f) HEPES (0.06 mol⋅kg−1) + NaHEPES (0.06 mol⋅kg−1) + NaCl (0.10 mol⋅kg−1); (g) HEPES (0.07 mol⋅kg−1) + NaHEPES (0.07 mol⋅kg−1) + NaCl (0.09 mol⋅kg−1); and (h) HEPES (0.08 mol⋅kg−1) + NaHEPES (0.08 mol⋅kg−1) + NaCl (0.08 mol⋅kg−1). Conventional pa
H values, for all eight buffer solutions from 5 to 55 °C, have been calculated. The operational pH values with liquid junction
corrections, at 25 and 37 °C have been determined based on the NBS/NIST standard between the physiological phosphate standard
and four buffer solutions. These are recommended as pH standards for physiological fluids in the range of pH = 7.3 to 7.5
at I=0.16 mol⋅kg−1. 相似文献
269.
A simple, rapid, and solvent-free method for quantitative determination of benzene, toluene, and Xylene in exposed Drosophila larvae was developed using headspace solid-phase microextraction (HS-SPME) coupled to GC/MS. Larvae fed on standard Drosophila food mixed with benzene, toluene, and Xylene for 48 h were homogenized in Milli-Q water. Extraction of benzene, toluene, and Xylene was performed at 65 degrees C for 30 min on the SPME fiber (silica-fused). Subsequently, the fiber was desorbed in the GC injection port, followed by GC/MS analysis in the selected-ion monitoring mode. An external calibration curve was used for the quantification of benzene, toluene, and Xylene in the exposed organism. Recoveries were in the range of 78-82% (intraday) and 76-81% (interday) in larvae, and 91-96% (intraday) and 87-92% (interday) in the diet. LOD with an S/N of 3:1 and LOQ with an S/N of 10:1 were in the range of 0.01-0.023 and 0.034-0.077 microg/L, respectively. Percent RSD values for benzene, toluene, and Xylene were in the range of 0.50-0.81 (intraday) and 0.89-1.23 (interday) for retention time, and 2.16--3.85 (intraday) and 2.99-4.95 (interday) for peak concentration, showing good repeatability. This method was sensitive enough to quantitate benzene, toluene, and Xylene in small exposed organisms like Drosophila larvae. The SPME/GC/MS method developed may have wider applications in various in vivo toxicological studies. 相似文献
270.
A convenient protocol for the synthesis of chiral pyran and piperidine ring-fused anthraquinone derivatives has been developed from (R)-2,3-O-cyclohexylidene-glyceraldehyde using sequential applications of enyne metathesis, Diels–Alder reaction and aromatization as key steps. 相似文献