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121.
Platelet-derived microparticles (PMPs) formed by vesiculation during platelet activation seem to play a role in blood coagulation and in pathological disease states. Flow cytometry is currently the gold standard to characterize platelets and PMPs. Using this technique we distinguished between platelets and PMPs based on size and the presence of phosphatidyl serine (PS); PMPs were arbitrarily defined to be smaller than one micrometer and capable of forming a stable complex with fluorescently-labeled Annexin V, a protein that forms a calcium-dependent complex with PS. Further confirmation of PMP and platelet identity was done by use of fluorescently-labeled antibodies against CD41a, a glycoprotein found on the surface of both platelets and PMPs. In this report we also introduce the use of capillary electrophoresis with post-column laser-induced fluorescence detection (CE-LIF) for the analysis of fluorescently labeled platelets and PMPs. While both flow cytometry and CE-LIF can measure individual fluorescent events, only CE-LIF allowed us to calculate individual electrophoretic mobilities of activated platelets and PMPs that were then represented as distributions. A comparison between distributions suggests that PMPs have less negative mobilities. The fact that activated platelet preparations include PMPs partially obscure the interpretation of the data. While PMP and platelet number ml(-1) determined by flow cytometry is lower than the same parameter determined by CE-LIF, signal-to-noise ratio was 20 fold better for flow cytometry than for CE-LIF. This is the first time that a direct comparison between these two techniques is reported. 相似文献
122.
Yilmaz Veysel T. Hamamci Sevim Andac Omer Thöne Carsten Harrison William T.A. 《Transition Metal Chemistry》2003,28(6):676-681
Mono- and binuclear copper(II) saccharinate (sac) complexes containing 2-pyridinepropanol (pypr) have been prepared and characterized by elemental analyses, i.r., u.v.–vis., magnetic measurements and single crystal X-ray diffraction. The copper(II) ion in trans-[Cu(pypr)2(sac)2] has –1 site symmetry and is octahedrally coordinated by two bidentate neutral pypr (N, O) and two sac (O) ligands. The binuclear copper(II) complex, [Cu2(-pypr)2(sac)2], is built up around a centre of symmetry and contains two strongly distorted square–planar coordinated copper(II) ions bridged by two alkoxo groups of the deprotonated pypr ligand, which also coordinates to the copper(II) ions through its nitrogen. In contrast to the mononuclear complex, the sac ligands in the binuclear complex is N-coordinated. The binuclear complex exhibits diamagnetic behaviour. The i.r. spectra and thermal decompositions of both complexes are described. 相似文献
123.
The charge distributions in a series of molecules A and their ions A+ and A2+ and in a second series B and their ions BH+ and BH2+ are presented. It is shown that their distributions are consistent with the conventional concepts of electronegativity, but not with those of the intermediate ion structures in the charge localisation concept of fragmentation processes in mass spectrometry. The charge distributions show that the carbon adjacent to a heteroatom has a considerable positive charge which apparently makes its bond to the next carbon atom weak and prone to fission which is a dominant process in the fragmentation of the positive ion. 相似文献
124.
Omer Sahin Fevzi Aslan Mustafa Ozdemir Mustafa Durgun 《Journal of Crystal Growth》2004,270(3-4):604-614
Growth rate of polycrystalline disc of borax compressed at different pressure and rotated at various speed has been measured in a rotating disc crystallizer under well-defined conditions of supersaturation. It was found that the mass transfer coefficient, K, increased while overall growth rate constant, Kg, and surface reaction constant, kr, decreased with increasing smoothness of the disc. It was also determined that kinetic parameters (kr,r,K,g) of crystal growth rate of borax decreased with increasing rotating speed of the polycrystalline disc. The effectiveness factor was calculated from the growth rate data to evaluate the relative magnitude of the steps in series bulk diffusion through the mass transfer boundary layer and the surface integration. At low rotating speed of disc, the crystal growth rate of borax is mainly controlled by integration. However, both diffusion and integration steps affect the growth rate of borax at higher rotating speed of polycrystalline disc. 相似文献
125.
Perwez Alam Omar M. Noman Rashed N. Herqash Omer M. Almarfadi Ali Akhtar Ali S. Alqahtani 《Molecules (Basel, Switzerland)》2022,27(1)
In this study, ultrasound-assisted extraction conditions were optimized to maximize the yields of sennoside A, sennoside B, aloe-emodin, emodin, and chrysophanol from S. alexandrina (aerial parts). The three UAE factors, extraction temperature (S1), extraction time (S2), and liquid to solid ratio (S3), were optimized using response surface methodology (RSM). A Box–Behnken design was used for experimental design and phytoconstituent analysis was performed using high-performance liquid chromatography-UV. The optimal extraction conditions were found to be a 64.2 °C extraction temperature, 52.1 min extraction time, and 25.2 mL/g liquid to solid ratio. The experimental values of sennoside A, sennoside B, aloe-emodin, emodin, and chrysophanol (2.237, 12.792, 2.457, 0.261, and 1.529%, respectively) agreed with those predicted (2.152, 12.031, 2.331, 0.214, and 1.411%, respectively) by RSM models, thus demonstrating the appropriateness of the model used and the accomplishment of RSM in optimizing the extraction conditions. Excellent antioxidant properties were exhibited by S. alexandrina methanol extract obtained using the optimized extraction conditions with a DPPH assay (IC50 = 59.7 ± 1.93, µg/mL) and ABTS method (47.2 ± 1.40, µg/mL) compared to standard ascorbic acid. 相似文献
126.
Omer Andac Yildiray Topcu Veysel T. Yilmaz Kutalmis Guven 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(12):1381-1384
The structures of the title triethanolamine (tea) complexes of CdII and HgII saccharinates, bis(triethanolamine)-κ3O,N,O′;κ4O,N,O′,O′′-cadmium(II) 1,2-benzisothiazol-3(2H)-onate 1,1-dioxide, [Cd(C6H15NO3)2](C7H4NO3S)2, (I), and bis(triethanolamine)-κ3O,N,O′;κ4O,N,O′,O′′-mercury(II) 1,2-benzisothiazol-3(2H)-onate 1,1-dioxide, [Hg(C6H15NO3)2](C7H4NO3S)2, (II), or [M(tea)2](sac)2, where M is CdII or HgII and sac is the saccharinate anion, reveal seven-coordinate metal ions in both complexes. Both complex cations, [M(tea)2]2+, adopt a monocapped trigonal prism geometry in which the two tea ligands exhibit different coordination modes to achieve seven-coordination. One tea ligand acts as a tetradentate ligand using all its donor atoms, while the other behaves as a tridentate O,N,O′-donor ligand, with one of its ethanol groups remaining uncoordinated. The H atoms of the free and coordinated hydroxyl groups of the tea ligands are involved in hydrogen bonding with the amine N atom, and with the carbonyl and sulfonyl O atoms of neighbouring sac ions, forming an infinite three-dimensional network. A weak π–π interaction between the phenyl rings of the sac ions also occurs. 相似文献
127.
The laminar flow through an axisymmetric sudden expansion was investigated experimentally using real-time digital particle image velocimetry. An expansion ratio (downstream-to-upstream pipe diameter ratio) of 2 was selected for the study. The measurements covered the regions of separation, reattachment and re-development. Two dimensional velocity maps were obtained on the vertical center plane for six Reynolds numbers between 20 and 211, based on the upstream pipe diameter and bulk velocity. The stream function distributions are calculated and presented from the streamwise and radial velocity maps. The dependence of reattachment length, redevelopment length and recirculating flow strength on the Reynolds number are determined. Results show that not only the reattachment length but also the redevelopment length downstream of reattachment is a linear function of the Reynolds number. The recirculation eddy strength, on the other hand, has a non-linear dependence on the Reynolds number which becomes weaker as the Reynolds number is increased. The results indicate no instability- or buoyancy-driven flow asymmetry in the range 20?Re? 211. 相似文献
128.
Water adsorbed on Ni(1 1 1) forms an ordered, hydrogen bonded ice structure with a (2√7 × 2√7)R19° unit cell. The 2√7 wetting structure forms as islands and persists up to saturation of the first layer. Adsorption of a fraction of a monolayer more water into a second layer destroys the 2√7 registry and creates a disordered ice film. Gas adsorption measurements indicate that the wetting layer is completely covered by a second layer of water before thicker multilayer ice forms. As the second layer is completed the film orders to form an incommensurate crystalline ice film with a hexagonal LEED pattern, oriented to the Ni close packed rows. This ordered, incommensurate structure persists as the ice multilayer grows thicker. 相似文献
129.
Omer Andac Yildiray Topcu Veysel T. Yilmaz William T.A. Harrison 《Journal of chemical crystallography》2000,30(12):767-771
The crystal structure of trans-bis(monoethanolamine)bis(saccharinato)nickel(II), [Ni(C7H4NO3S)2(C2H7NO)2], has been determined from X-ray diffraction data. The metal complex is monoclinic, with a = 11.0555(5), b = 8.9103(4), c = 11.3890(5) Å, = 105.0230(10)°, Z = 2, and space group P21/c
. The structure consists of individual molecules. Two monoethanolamine molecules and two saccharinate anions coordinate the nickel atom forming a distorted octahedron. The monoethanolamine molecules act as a bidentate ligand and form five-membered trans chelate rings, which constitute the plane of the coordination octahedron, while two saccharinate ions behave as a monodentate ligand occupying the axial positions. Intermolecular hydrogen bonds link the molecules to form a three-dimensional infinite structure. 相似文献
130.
We are investigating the use of capacitive micromachined ultrasonic transducers (cMUT's) for use in medical imaging. We propose an ultrasound probe architecture designed to provide volumetric ultrasound imaging from within an endoscope channel. A complete automated experimental system has been implemented for testing the imaging performance of cMUT arrays. This PC-based system includes custom-designed circuit boards, a software interface, and resolution test phantoms. We have already fabricated 1D and 2D cMUT arrays, and tested the pulse-echo imaging characteristics of 1D arrays. Beamforming and image formation algorithms that aim to reduce the complexity of data acquisition hardware are tested via numerical simulations and using real data acquired from our system. 相似文献