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51.
Hematopoietic stem cells are larger in size than other cells present in bone marrow, with the exception of monocytes. This distinguishing characteristic can be used to separate them from a whole-marrow sample. A microfluidic device was fabricated using an integrated membrane that is porous at defined areas. This allows for simultaneous valving and filtering functionality, which is crucial for preventing irreversible clogging. This device, as well as a separation procedure, was optimized in this work to enrich hematopoietic progenitor cells from diluted bone marrow of leukemia patients without any additional sample preparation. An enrichment of up to 98% was achieved with this method and the process was scaled up to 17.2 μL min(-1) of processed sample. Additionally, stem cells were stained with specific antibodies for further analysis. Using a custom-made computer program, the filter was scanned to characterize and quantify cells based on fluorescence. The results were evaluated by comparing them against the results obtained from flow cytometry, confocal microscopy, and Coulter counting. 相似文献
52.
Heshmatollah Alinezhad Mahmood Tajbakhsh Mahboobeh Zare 《Journal of fluorine chemistry》2011,132(11):995-1000
A simple, efficient and three component one-pot synthesis of 1,4,5-trisubstituted pyrazoles by condensation of β-dicarbonyls, N,N-dimethylformamide dimethyl acetal (DMFDMA) and hydrazine derivatives in 2,2,2-trifluoroethanol without using any catalyst and activation, is described. 相似文献
53.
54.
Navid Nasirizadeh Hamid R. Zare Ali R. Fakhari Hamid Ahmar Mohammad R. Ahmadzadeh Amin Naeimi 《Journal of Solid State Electrochemistry》2011,15(11-12):2683-2693
In this study, an oxadiazole multi-wall carbon nanotube-modified glassy carbon electrode (OMWCNT?GCE) was used as a highly sensitive electrochemical sensor for hydrazine determination. The surface charge transfer rate constant, k s, and the charge transfer coefficient, ??, for electron transfer between GCE and electrodeposited oxadiazole were calculated as 19.4?±?0.5?s?1 and 0.51, respectively at pH?=?7.0. The obtained results indicate that hydrazine peak potential at OMWCNT?GCE shifted for 14, 109, and 136?mV to negative values as compared with oxadiazole-modified GCE, MWCNT?GCE, and activated GCE surface, respectively. The electron transfer coefficient, ??, and the heterogeneous rate constant, k??, for the oxidation of hydrazine at OMWCNT?GCE were also determined by cyclic voltammetry measurements. Two linear dynamic ranges of 0.6 to 10.0???M and 10.0 to 400.0???M and detection limit of 0.17???M for hydrazine determination were evaluated using differential pulse voltammetry. In addition, OMWCNT?GCE was shown to be successfully applied to determine hydrazine in various water samples. 相似文献
55.
Medium-resolution spectra of the N2 b1Πu-X1Σg+ band system were recorded by 1 + 1 multiphoton ionization. In the spectra we found different linewidths for transitions to different vibrational levels in the b 1Πu state: Δν0 = 0.50 ± 0.05 cm−1, Δν1 = 0.28 ± 0.02 cm−1, Δν2 = 0.65 ± 0.06 cm−1, Δν3 = 3.2 ± 0.5 cm−1, Δν4 = 0.60 ± 0.07 cm−1, and Δν5 = 0.28 ± 0.02 cm−1. From these linewidths, predissociation lifetimes τν were obtained: τ0 = 16 ± 3 ps, τ1 > 150 ps, τ2 = 10 ± 2 ps, τ3 = 1.6 ± 0.3 ps, τ4 = 9 ± 2 ps, and τ5 > 150 ps. Band origins and rotational constants for the b 1Πuν = 0 and 1 levels were determined for the 14N2 and 14N15N molecules. 相似文献
56.
M. Mazloum Ardakani Z. Akrami H. Kazemian Hamid R. Zare 《Journal of Analytical Chemistry》2008,63(2):184-191
Chemically modified electrodes based on zeolite-containing graphite pastes were constructed and evaluated as sensor electrodes for the voltammetric determination of trace cobalt in solution. Zeolite molecular sieves with pore sizes of 3, 4, and 5 Å were all suitable for chemical deposition and subsequent voltammetric quantitation of trace Co(II). In order to cover a large range of parameters, the investigations were carried out using three zeolites (A, X, and Y), selected for their different cation-exchange capacities and ion-sieving properties. The analytical scheme, “preconcentration/voltammetric detection” for the determination of cobalt(II) species using zeolite-modified carbon paste electrodes (ZMCPE) was chosen. Compared to the corresponding unmodified electrodes, improvements in sensitivity were observed when using ZMCPEs due to analyte accumulation at the electrode’s surface by ion exchange in zeolite particles. The detection limit obtained for Co(II) was 3 ppm following 15 min of chemical deposition. A good correlation was found between the results obtained by ion exchange voltammetry and conventional ion-exchange characterization. 相似文献
57.
Camden JP Bechtel HA Ankeny Brown DJ Martin MR Zare RN Hu W Lendvay G Troya D Schatz GC 《Journal of the American Chemical Society》2005,127(34):11898-11899
A comparison between theory and experiment for the benchmark H + CD4 --> HD + CD3 abstraction reaction yields a reinterpretation of the reaction mechanism and highlights the unexpected contribution of a stripping mechanism. Whereas the best analytic surface fails to reproduce experiment, a first-principles direct-dynamics (on the fly) treatment is in good agreement, showing that the H + CD4 reaction exhibits extreme sensitivity to modest differences in the potential energy surface. We find that bent H-D-C transition state geometries play an important role in the dynamics. A simple model that relates the scattering angle impact parameter and cone of acceptance accounts well for the overall reaction dynamics. 相似文献
58.
D.L. Albritton W.J. Harrop A.L. Schmeltekopf R.N. Zare 《Journal of Molecular Spectroscopy》1973,46(1):25-36
Expressions are developed for computing the centrifugal distortion constants Dv, Hv, and Lv directly from the Rydberg-Klein-Rees rotationless potential of a diatomic molecule. These expressions involve summations over integrals of the wavefunctions of all neighboring vibrational levels. Application is made to the X1Σ+ state of CO and the state of O2. In these applications, we have neglected the contributions of the continuum wavefunctions. For higher vibrational levels, particularly those near the dissociation limit, this approximation would be expected to fail. For the lowest vibrational levels of an electronic state, this method gives the same results for Dv, Hv, and Lv as the Dunham relations. However, for intermediate vibrational levels the present method is an improvement since expressions for only a few coefficients of the Dunham expansion are available. The use of Dv and Hv values calculated from Rydberg-Klein-Rees potentials in an iterative improvement of the reduction of spectroscopic data is described. 相似文献
59.
D.L. Albritton W.J. Harrop A.L. Schmeltekopf R.N. Zare 《Journal of Molecular Spectroscopy》1973,46(1):103-118
The discrepancies concerning the optical and microwave values of B0 and D0 for the X state of O2 have been removed by a nonlinear least-squares fit to all of the lines of the O2, Red Atmospheric bands recorded by Babcock and Herzberg (Astrophys. J., 108, 167, 1948). The resulting values for B0″ and D0″ are in excellent agreement with the Raman and microwave values. Improved values are determined for B1″, D1″, γ1″ (spin-rotation), and ?1″ (spin-spin). Both γv″ and ?v″ increase in magnitude from v″ = 0 to v″ = 1. Improved Dunham Yi0 and Yi1 expansion coefficients are determined for the state, from which the Rydberg-Klein-Rees potential is constructed. 相似文献
60.
Emission resulting, from collisions of 5–200 eV electrons with gaseous HgX2, and CH3HgX (X = Cl, Br. I) was characterized in the 3800–5600 A region. HgX BX emission dominates and absolute cross section as a function of electron energy were determined. The formation of electronically excited Hg atoms, and the trend of the cross sections with the nature of the halogen atom are discussed in terms of a simple charge transfer model. 相似文献