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911.
Analytical magnetapheresis is a newly developed technique for analyzing magnetic particles. The magnetically susceptible particles form deposition patterns after flowing through a separation channel in a magnetic field. The separation channel requirements for analytical magnetapheresis are an excellent seal for the carrier flow and ease of disassembly after magnetapheresis. Previously used separation channels often exhibit variable channel leakage and unstable flow velocities. We improved the separation channel assembly to ensure stable, high flow velocities and characterized the system with various magnetically susceptible and labeled particles. Our new separation channel featured silicone sealant with embedded nylon wires and met analytical magnetapheresis requirements. Characterization of this system was performed using several magnetically susceptible particles, and we studied a variety of diamagnetic sample labels with paramagnetic ions and magnetically susceptible particles at different flow-rates and solution pH values. The minimal labeling concentration for complete deposition was determined to be approximately 2.50 x 10(10) ions per particle for test samples at a flow velocity of 0.67 mm s(-1) and a magnetic field gradient of 2.8 T mm(-1). Silicas, yeasts and blood cells were used for these studies. We determined that the minimal difference in magnetic susceptibility (delta(chi)) for successful separation was approximately 2.00 x 10(-6) [SI]. The magnetic susceptibilities of Dynabeads M-450 at several separation distances and flow-rates were determined to be 0.25 [SI], within 2% of values published by other workers. The magnetic susceptibilities of various ion-labeled yeasts and cells were determined and most varied by less than 5% at different flow-rates. The results of this study provide very important references for analytical magnetapheresis applications. 相似文献
912.
Lai‐Cai Li Ping Deng Yuan‐Qiang Zhu Dong Zha An‐Min Tian Ming‐Hou Xu Ning‐Bew Wong 《International journal of quantum chemistry》2005,104(3):367-372
In this work ab initio molecular orbital methods were employed to study the coal combustion reaction mechanisms of tin oxidized by different oxidants, including HOCl, HCl, ClO, ClO2, NO3, CO2, and O2. Eleven reaction pathways were identified. The results show that Sn can react with HCl, ClOO, CO2, O2, and NO3 to form SnO and SnCl. SnO can be oxidized into SnCl by HOCl and HCl. SnCl can be further oxidized into a soluble compound, SnCl2. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
913.
914.
Three bulky mono-dentate alkyne-bridged dicobalt-phosphine complexes [(μ-PPh2CH2PPh2)Co2(CO)4](μ,η-PhCCPPh2) 4a, [(μ-PPh2CH2PPh2)Co2(CO)4](μ,η-Me3CCCPPh2) 5a and [(μ-PPh2CH2PPh2)Co2(CO)4](μ,η-Me3SiCCPPh2) 6a were prepared from the reactions of the bis(diphenylphosphino)methylene (dppm) bridged dicobalt complex Co2(CO)6(μ-Ph2PCH2PPh2) with PhCCPPh21, Me3CCCPPh22, and Me3SiCCPPh23, respectively. These three metal-containing compounds 4a, 5a and 6a were employed as ligands, replacing conventional organic phosphines, in the Suzuki cross-coupling reactions and have been proved to be effective, authentic mono-dentate phosphine ligands. 相似文献
915.
Shyh‐Ying Chiou Gin‐Win Lai Yi‐Hon Tsai Yu‐Ru Lee Long‐Yau Lin Gia‐Lih Lin 《中国化学会会志》2005,52(4):843-848
The goal of this work is to determine enzyme kinetics and mechanisms of acetylcholinesterase and butyrylcholinesterase inhibition by five cardiovascular drugs, lovastatin, simvastatin, amlodipine besylate, nifedipine, and hydralazine hydrochloride, and two benzodiazepines, diazepam and chlordiazepoxide hydrochloride. All drugs in this study are reversible mixed‐type inhibitors of acetylcholinesterase and butyrylcholinesterase. The pKi values for acetylcholinesterase and butyrylcholinesterase inhibition by the cardiovascular drugs are linearly correlated with the molecular weights of the drugs with the slopes of 0.005 and 0.0021, respectively. Therefore, van der Waals' interactions between acetylcholinesterase and the cardiovascular drugs are stronger than those between butyrylcholinesterase and the drugs. This is probably due to a smaller active site gorge and a more significant peripheral anionic substrate binding site of acetylcholinesterase than those of butyrylcholinesterase. The fact that the pKi values for both butyrylcholinesterase and acetylcholinesterase inhibition by the cardiovascular drugs are linearly correlated with each other suggests that both enzyme inhibition reactions proceed via a common mechanism. Furthermore, amlodipine besylate may be useful in Alzheimer's disease treatment similar to donepezil. 相似文献
916.
The sol-gel processing of lead-free (Na,K) NbO3 ferroelectric films was studied. Sodium ethoxide (NaOC2H5) and potassium ethoxide (KOC2H5) were prepared by reacting solid Na and K with ethanol (99.7%) in a solvent of 2-methoxyethanol. 0.5-μm-thick (Na,K)NbO3 thin films with orthorhombic perovskite structure were obtained by pyrolyzing at 400°C and annealing at 800–900°C. The films
had relatively dense and uniform microstructure with grain size of about 50 nm, whose ferroelectricity was proved by the P-E hysteresis loop measurement. It was found that excess K was effective to reduce the annealing temperature for the crystallization
of sol-gel-derived (Na,K)NbO3 thin films. 相似文献
917.
918.
A novel method for preparation of hydrogen peroxide biosensor was presented based on immobilization of hemoglobin (Hb) on carbon‐coated iron nanoparticles (CIN). CIN was firstly dispersed in a chitosan solution and cast onto a glassy carbon electrode to form a CIN/chitosan composite film modified electrode. Hb was then immobilized onto the composite film with the cross‐linking of glutaraldehyde. The immobilized Hb displayed a pair of stable and quasireversible redox peaks and excellent electrocatalytic reduction of hydrogen peroxide (H2O2), which leading to an unmediated biosensor for H2O2. The electrocatalytic response exhibited a linear dependence on H2O2 concentration in a wide range from 3.1 μM to 4.0 mM with a detection limit of 1.2 μM (S/N=3). The designed biosensor exhibited acceptable stability, long‐term life and good reproducibility. 相似文献
919.
Cp2Cr2(CO)4( - 2 - P2), 1, reacts with one molar equivalent of Fe2(CO)9 in THF to yield the mono- and di-iron complexes, Cp2Cr2(CO)4P2[Fe(CO)4], 2, (16.5% yield) and Cp2Cr2(CO)4P2[Fe(CO)4]2, 3, (16.9% yield), as dark magenta brown and dark greenish brown crystals, respectively. Both complexes were characterized by single-crystal X-ray diffraction analysis. Crystal data –2: space group =P21/c,a=17.024(1) Å,b=8.180(1) Å,c=30.891(2) Å, =100.953(5)°,V=4223.4(7)Å3,Z=8, 3743 observed reflections,R
F=0.033; 3: space group P1,a=10.209(2) Å,b=10.212(2) Å,c=15.989(3) Å, =106.93(1)°, =91.87(1)°, =119.50(1)°,V=1356.5(4) Å3,Z=2, 3489 observed reflections,R
F=0.029. 相似文献
920.
Ding L Weiss TM Fragneto G Liu W Yang L Huang HW 《Langmuir : the ACS journal of surfaces and colloids》2005,21(1):203-210
The recent discovery of a distorted hexagonal phase in 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine/1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPE/DOPC) mixtures raised the intriguing question as to whether lipid mixtures demix in a bent monolayer. We performed neutron diffraction on a mixture of headgroup deuterated DOPC-d(13) and nondeuterated DOPE to study the lipid distribution in the distorted hexagonal phase. The 1:1 lipid mixture in full hydration and 25 degrees C was in a homogeneous lamellar phase. Upon dehydration the mixture transformed to a rhombohedral phase, then to a distorted inverted hexagonal phase, and finally to a regular inverted hexagonal phase. In the distorted hexagonal phase, the diffraction pattern showed a two-dimensional monoclinic lattice with two reciprocal vectors of equal length (1.5 nm(-)(1)) forming an angle 53 degrees between them. Diffraction intensities measured while varying the D(2)O/H(2)O ratio in the humidity was used to solve the phase problem. The neutron scattering length density distribution of the distorted hexagonal phase was constructed. The constant density contours are approximately elliptical. The difference in the eccentricities of the contours between the water and lipid distributions indicates that the DOPE/DOPC ratio is not uniform around the elliptical lipid tube in the unit cell. DOPE is preferentially distributed at the vertex regions where the curvature is the highest. Thus for the first time it is shown that when a monolayer of a homogeneous lipid mixture is bent, the lipid components are partially demixed in reaching the free energy minimum. 相似文献