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151.
Moulton SE Barisci JN Bath A Stella R Wallace GG 《Journal of colloid and interface science》2003,261(2):312-319
The adsorption of two model proteins, human serum albumin and immunoglobulin G, on a gold electrode surface was investigated using 125I radiolabeling and cyclic voltammetry (CV). 125I radiolabeling was used to determine the extent of protein adsorption, while CV was used to ascertain the effect of the adsorbed protein layer on the electron transfer between the gold electrode and an electroactive moiety in solution, namely, K3Fe(CN)6. The adsorbed amounts of HSA and IgG agreed well with previous results and showed approximately monolayer coverage. The amount of adsorbed protein increased when a positive potential (700 mV) was applied to the electrode, while the application of a negative potential (-800 mV) resulted in a decrease. When the solution pH was varied to alter the charge on the protein, the adsorption trends appeared to follow electrostatic interaction, namely, greater adsorption when the electrode and the protein possessed opposite charge and vice versa. The adsorbed protein layer had the effect of blocking the electron transfer. It was possible to correlate the degree of electron blocking with the amount of adsorbed protein to show that the greater the adsorption, the larger the blocking effect. Of the two proteins used, HSA proved to be more efficient at blocking the electron transfer. 相似文献
152.
Stella T. Giroussi Anastasios N. Voulgaropoulos Aristomenis Ayiannidis 《Analytical and bioanalytical chemistry》1997,357(4):429-432
A selective, sensitive and reliable voltammetric method for the simultaneous determination of Cu and Mo is developed. Both
metals form complexes with 8-hydroxyquinoline (oxine). Mo gives two reduction peaks with oxine in acidic chloride media at
−0.52 V and −0.58 V, while copper exhibits only one at −0.14 V. Common heavy metals do not interfere at all. The limit of
detection is 0.29 ng/ml for Mo and 0.14 ng/ml for Cu after preconcentration on the hanging mercury drop electrode for 30 s
at −0.2 V. The R.S.D. at a concentration level of 10 ng/ml is 3.8% for Cu and 5.3% for Mo. The method is applied to different
biological samples.
Received: 15 January 1996/Revised: 11 April 1996/Accepted: 16 April 1996 相似文献
153.
Matteo?FocardiEmail author Maria?Stella?Gelli 《NoDEA : Nonlinear Differential Equations and Applications》2003,10(4):469-495
In this paper we deal with Monge-Ampère type equations in two
dimensions and, using the symmetrization with respect to the perimeter, we
prove some comparison results for solutions of such equations involving the
solutions of conveniently symmetrized problems. 相似文献
154.
Marinos Pitsikalis Stella Sioula Stergios Pispas Nikos Hadjichristidis Daniel C. Cook Jianbo Li Jimmy W. Mays 《Journal of polymer science. Part A, Polymer chemistry》1999,37(23):4337-4350
Anionic polymerization techniques utilizing 1,2,4,5-tetra(bromomethyl)- benzene as the linking agent were employed for the synthesis of four-arm star polymers with poly(tert-butyl methacrylate) (PtBuMA), poly(methyl methacrylate), poly(tert-butylacrylate) (PtBuA), or poly(2-vinylpyridine) (P2VP) branches. This work was extended through the “grafting onto” method, in combination with anionic polymerization techniques, to synthesize graft copolymers consisting of polystyrene backbones and PtBuA, PtBuMA, or P2VP branches. Postpolymerization reactions were performed to produce graft copolymers with polyelectrolyte branches. Crosslinking reactions were observed in some of the graft materials several months after their preparation. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4337–4350, 1999 相似文献
155.
The synthesis of model miktoarm stars of the A2B, A3B, (AB)2(BA)2 and ABC (A:polyisoprene, B: polystyrene C: poly (methyl methacrylate)) was achieved by using anionic polymerization techniques and controlled chlorosilane chemistry. The microphase separation was studied by TEM, SAXS and image simulation. In the case of A2B and A3B miktoarm star copolymers, the morphology results are in agreement with the newly and after the experimental results developed theory of Milner. One of the symmetric in composition inverse block copolymers ((AB)2(BA)2) shows the OBDD morphology due to the special spatial arrangements of the arms. The first morphological results of ABC miktoarm star terpolymer show interesting future. 相似文献
156.
157.
2,2,3,4,4-pentamethylphosphetanic acid,C8H16PO2H: salts,complexes and a hydrogen bonded amine adduct
John Emsley Amanda P. Dunning Robert J. Parker John K. Williams Shirley Brown Stella Earnshaw David S. Moore 《Polyhedron》1984,3(3):325-329
The conjugate base of the title acid, i.e. C8H16PO2?, has been investigated as its simple salts, as a ligand in transition metal complexes of cobalt and ruthenium, and as a secondary amonium salt in which hydrogen bonding between anion and cation occurs. 相似文献
158.
Electron beam lithography designed chemical nanosensors based on localized surface plasmon resonance
G. Barbillon J. Plain M. Lamy de la Chapelle P.-M. Adam P. Royer 《Surface science》2007,601(21):5057-5061
Efficient nanochemosensors designed by electron beam lithography and based on localized surface plasmon resonance excited on noble metal nanocylinders are presented. Using localized surface plasmon resonance spectroscopy, we report here a high sensitivity corresponding to a density of about 18 × 10−21 mol of adsorbate per nanocylinders, we present the results obtained with gold and silver nanoparticles. This detection corresponds to less than one monolayer of molecules adsorbate on the nanoparticle. Additionally a subsequent layers deposition of polyelectrolytes is used to detect very thin polymer films. Although the results presented in this work are far from conclusive, the advantages of these nanochemosensors discussed here open the possibilities of further developments in a wide range of chemical and medical applications. 相似文献
159.
A single sandpile model with quenched random toppling matrices captures the crucial features of different models of self-organized criticality. With symmetric matrices avalanche statistics falls in the multiscaling Bak-Tang-Wiesenfeld universality class. In the asymmetric case the simple scaling of the Manna model is observed. The presence or absence of a precise toppling balance between the amount of sand released by a toppling site and the total quantity the same site receives when all its neighbors topple once determines the appropriate universality class. 相似文献
160.
Lu CJ Steinecker WH Tian WC Oborny MC Nichols JM Agah M Potkay JA Chan HK Driscoll J Sacks RD Wise KD Pang SW Zellers ET 《Lab on a chip》2005,5(10):1123-1131
The fabrication, assembly, and initial testing of a hybrid microfabricated gas chromatograph (microGC) is described. The microGC incorporates capabilities for on-board calibration, sample preconcentration and focused thermal desorption, temperature-programmed separations, and "spectral" detection with an integrated array of microsensors, and is designed for rapid determinations of complex mixtures of environmental contaminants at trace concentrations. Ambient air is used as the carrier gas to avoid the need for on-board gas supplies. The microsystem is plumbed through an etched-Si/glass microfluidic interconnection substrate with fused silica capillaries and employs a miniature commercial pump and valve subsystem for directing sample flow. The latest performance data on each system component are presented followed by first analytical results from the working microsystem. Tradeoffs in system performance as a function of volumetric flow rate are explored. The determination of an 11-vapor mixture of typical indoor air contaminants in less than 90 s is demonstrated with projected detection limits in the low part-per-billion concentration range for a preconcentrated air-sample volume of 0.25 L. 相似文献