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31.
In this paper, a sensitive water-soluble fluorescent conjugated polymer biosensor for catecholamine (dopamine DA, adrenaline AD and norepinephrine NE) was developed. In the presence of horse radish peroxidase (HRP) and H(2)O(2), catecholamine could be oxidized and the oxidation product of catecholamine could quench the photoluminescence (PL) intensity of poly(2,5-bis(3-sulfonatopropoxy)-1,4-phenylethynylenealt-1,4-poly(phenylene ethynylene)) (PPESO(3)). The quenching PL intensity of PPESO(3) (I(0)/I) was proportional to the concentration of DA, AD and NE in the concentration ranges of 5.0 × 10(-7) to 1.4 × 10(-4), 5.0 × 10(-6) to 5.0 × 10(-4), and 5.0 × 10(-6) to 5.0 × 10(-4) mol L(-1), respectively. The detection limit for DA, AD and NE was 1.4 × 10(-7) mol L(-1), 1.0 × 10(-6) and 1.0 × 10(-6) mol L(-1), respectively. The PPESO(3)-enzyme hybrid system based on the fluorescence quenching method was successfully applied for the determination of catecholamine in human serum samples with good accuracy and satisfactory recovery. The results were in good agreement with those provided by the HPLC-MS method. 相似文献
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Karm Hans Masood Parvez Sumera Mahboob Imtiaz‐ud‐Din Muhammad Mazhar Saqib Ali 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(11):m559-m562
The central Ge atoms in the structures of 3‐(2‐fluorophenyl)‐3‐(triphenylgermyl)propionic acid, [Ge(C6H5)3(C9H8FO2)], 3‐(2‐tolyl)‐3‐(tri‐4‐tolylgermyl)propionic acid, [Ge(C7H7)3(C10H11O2)], and 3‐(4‐tolyl)‐3‐(tribenzylgermyl)propionic acid, [Ge(C7H7)3(C10H11O2)], are four‐coordinate with slightly distorted tetrahedral geometry. The Ge—Csp3 distances [1.970 (3)–1.997 (3) Å] are significantly longer than the Ge—Caromatic distances [1.940 (3)–1.959 (2) Å]. In all three structures, the molecules form dimeric pairs about inversion centres through strong hydrogen‐bonding interactions between carboxylic acid groups. 相似文献
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Shelf life of the formulations designed for the industrial manufacture of radiation sterilizable syringes and other medical disposables is a very important issue world over. Radiation compatible formulations were developed earlier in the laboratory by the incorporation of primary and secondary antioxidants along with processing stabilizers in a random polypropylene copolymer. It has been reported in literature that the mobilizing agents namely hydrocarbons, greases, wax and the plasticizer, dioctyl phthalate (DOP) impart radiation resistance to the polypropylene by providing free volume. It was envisaged that the addition of DOP to the afore-mentioned formulation might favorably influence the mechanical, optical and thermal properties of our formulation. To study the influence of addition of DOP on the afore-mentioned properties, the addition of 1%, 2% and 3% of the mobilizer was made, followed by the irradiation of resulting heat pressed sheets to the industrial standard dose of 25 kGy. Two important characteristic mechanical properties to determine the suitability of the radiation sterilized materials comprise angle of breakage and the haze percent. After irradiation and even on accelerated ageing of the irradiated material, the angle of breakage of heat press sheets of formulations containing 1%, 2% and 3% of DOP was found to be 180°, demonstrating the role of DOP, in imparting additional radiation stability. In case of the irradiated control sample, the angle of breakage was much lower. In the heat pressed sheets containing the DOP, a remarkable retention in the tensile strength, percentage elongation at break, along with improved thermal stability was observed. The formulation devoid of DOP demonstrated poor retention of the afore-mentioned characteristic properties .The observed improvement in thermal stability of the formulations containing DOP hints at the likely possibility of reuse of these materials by autoclaving which is considered an additional attribute. 相似文献
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The Stokes and Rayleigh Stokes problems for a flat plate in a viscoelastic fluid has recently been generalized to an edge
and an exact analytical solution is obtained. In this paper, the edge problem has further been extended to the case of a rectangular
pipe and exact solutions are obtained for Maxwell and second grade fluids. Also, the flow due to an oscillating edge problem
is extended to generalized Maxwell fluid. 相似文献