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341.
The importance of the calibration of standard laboratory ware is pointed out. Tables for use in calibration of polypropylene and polymethylpentene vessels are presented. 相似文献
342.
Trischuk W de Troconiz JF Truitt S Tseng J Turini N Ukegawa F Valls J Vejcik S Velev G Vidal R Vilar R Vologouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C Wang CH Wang MJ Watanabe T Waters D Watts T Webb R Wenzel H 《Physical review letters》2000,84(5):835-840
We present the results of a search for pair production of a fourth-generation charge -1 / 3 quark (b(')) in sqrt[s] = 1.8 TeV p&pmacr; collisions using 88 pb(-1) of data obtained with the Collider Detector at Fermilab. We assume that both quarks decay via the flavor-changing neutral current process b(')-->bZ(0) and that the b(') mass is greater than m(Z)+m(b). We studied the decay mode b(')b(');-->Z(0)Z(0)b&bmacr; where one Z0 decays into e(+)e(-) or &mgr;(+)&mgr;(-) and the other decays hadronically, giving a signature of two leptons plus jets. An upper limit on the sigma(p&pmacr;-->b(')b(');)x[B(b(')-->bZ(0))](2) is established as a function of the b(') mass. We exclude at 95% confidence level a b(') quark with mass between 100 and 199 GeV/c(2) for B(b(')-->bZ(0)) = 100%. 相似文献
343.
Zwanenburg MJ Bongaerts JH Peters JF Riese DO van Der Veen JF 《Physical review letters》2000,85(24):5154-5157
We have determined the structure of a colloidal fluid confined in a gap between two walls by making use of the waveguiding properties of the gap at x-ray wavelengths. The method is based on an analysis of the coupling of waveguide modes induced by the density variations in the confined fluid. Studies on suspensions confined within gaps of a few hundred nanometers showed strongly selective mode coupling effects, indicative of an ordering of the colloidal particles in layers parallel to the confining walls. 相似文献
344.
Theriot D Thurman-Keup R Tipton P Tkaczyk S Tollefson K Tollestrup A Toyoda H Trischuk W de Troconiz JF Tseng J Turini N Ukegawa F Vaiciulis T Valls J Vejcik S Velev G Vidal R Vilar R Volobouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C 《Physical review letters》2000,85(16):3347-3352
This Letter describes a direct measurement of the W boson total decay width, gamma(W), using the Collider Detector at Fermilab. The measurement uses an integrated luminosity of 90 pb(-1), collected during the 1994-1995 run of the Fermilab Tevatron p&pmacr; collider. The width is determined by normalizing predicted signal and background distributions to 49 844 W-->enu candidates and 21 806 W-->&mgr;nu candidates in the transverse-mass region M(T)<200 GeV and then fitting the predicted shape to the 438 electron events and 196 muon events in the high- M(T) region, 100相似文献
345.
A chiral phosphoric acid (5)-catalyzed three-component Povarov reaction of aldehydes 2, anilines 3, and enecarbamates 4 afforded cis-4-amino-2-aryl(alkyl)-1,2,3,4-tetrahydroquinolines 1 in high yields with excellent diastereoselectivities (>95%) and almost complete enantioselectivities (up to >99% ee). The reaction was applicable to a wide range of anilines bearing electron-donating (OMe) and electron-withdrawing groups (e.g., Cl, CF(3), NO(2)) and allowed, for the first time, aliphatic aldehydes to be employed in the enantioselective Povarov reaction. With β-substituted acyclic enecarbamates, 2,3,4-trisubstituted 1,2,3,4-tetrahydroquinolines with three contiguous stereogenic centers were produced in excellent diastereo- and enantioselectivities (87 to >99% ee). A detailed study of the active catalytic species allowed us to reduce the catalyst loading from 10% to 0.5% with no deterioration of enantiomeric excess. In addition, mechanistic studies allowed us to conclude unequivocally that the Povarov reaction involving enecarbamate as dienophile proceeded via a stepwise mechanism. The key role of the free NH function of the enecarbamate in the success of this transformation was demonstrated. NMR experiments indicating the catalyst-substrate interaction as well as a linear correlation between catalyst and product ee's were also documented. 相似文献
346.
The steady-state absorption and fluorescence, as well as the time-resolved fluorescence properties of bisdemethoxycurcumin
dissolved in several solvents differing in polarity and H-bonding capability were measured. The photodegradation quantum yield
of the compound in acetonitrile and methanol was determined. The bisdemethoxycurcumin decay mechanisms from the S
1 state were discussed and compared with those of curcumin. The differences in S
1 dynamics observed between bisdemethoxy-curcumin and curcumin could be ascribed to a difference in H-bond acceptor/donor properties
of the phenolic OH and a difference in strength of the intramolecular H-bond in the keto-enol moiety within the two molecules. 相似文献
347.
Charles W. Blackledge Thibault Tabarin Emilie Masson Robert J. Forster Tia E. Keyes 《Journal of nanoparticle research》2011,13(10):4659-4672
Silica shells are grown around colloidally synthesized gold nanorods (AuNRs) to form core–shell particles (AuNR@SiO2) of variable occupancy, defined as the number of AuNRs per silica particle. Multiple AuNR occupancy within the silica shell,
confirmed with high-resolution electron microscopy, is reflected in a redshift of the longitudinal plasmon mode of the nanorods
due to multipolar coupling between AuNRs of a favored end–end orientation. In addition to the plasmon resonance that dominates
their absorbance spectra, FL-AuNR@SiO2, core–shell particles incorporating a lipid probe (rhodamine-DOPE), can be monitored by their fluorescence and Raman signals.
Optical and scanning electron microscopy (SEM) images are compared directly, enabling the correlation of spectroscopic characteristics
with particle morphology. Raman and SEM images show that the most intense Raman signals come from aggregates of AuNRs trapped
within the silica matrix. Biexponential fits to fluorescence decays indicate that competing mechanisms of quenching and fluorescence
enhancement contribute to a reduced fluorescence lifetime of rhodamine-DOPE located near the AuNRs. 相似文献
348.
Douradinha B van Dijk M van Gemert GJ Khan SM Janse CJ Waters AP Sauerwein RW Luty AJ Silva-Santos B Mota MM Epiphanio S 《Journal of immune based therapies and vaccines》2011,9(1):6-5
Background
The induction of sterile immunity and long lasting protection against malaria has been effectively achieved by immunization with sporozoites attenuated by gamma-irradiation or through deletion of genes. For mice immunized with radiation attenuated sporozoites (RAS) it has been shown that intrahepatic effector memory CD8+ T cells are critical for protection. Recent studies have shown that immunization with genetically attenuated parasites (GAP) in mice is also conferred by liver effector memory CD8+ T cells.Findings
In this study we analysed effector memory cell responses after immunization of GAP that lack the P52 protein. We demonstrate that immunization with p52 -GAP sporozoites also results in a strong increase of effector memory CD8+ T cells, even 6 months after immunization, whereas no specific CD4+ effector T cells response could be detected. In addition, we show that the increase of effector memory CD8+ T cells is specific for the liver and not for the spleen or lymph nodes.Conclusions
These results indicate that immunization of mice with P. berghei p52 -GAP results in immune responses that are comparable to those induced by RAS or GAP lacking expression of UIS3 or UIS4, with an important role implicated for intrahepatic effector memory CD8+ T cells. The knowledge of the mediators of protective immunity after immunization with different GAP is important for the further development of vaccines consisting of genetically attenuated sporozoites. 相似文献349.
Bolduc OR Lambert-Lanteigne P Colin DY Zhao SS Proulx C Boeglin D Lubell WD Pelletier JN Féthière J Ong H Masson JF 《The Analyst》2011,136(15):3142-3148
A peptide self-assembled monolayer (SAM) was designed to bind His-tagged biomolecules for surface plasmon resonance (SPR) bioanalysis, which was applied for the determination of K(d) for small ligand screening against CD36. Nonspecific adsorption could be minimized using penta- and hexa-peptide monolayers. In particular, monolayers consisting of 3-mercaptopropionyl-leucinyl-histidinyl-aspartyl-leucinyl-histidinyl-aspartic acid (3-Mpa-LHDLHD) exhibited little (12 ng cm(-2)) nonspecific adsorption in crude serum. Modification of this peptide monolayer with Nα,Nα-bis(carboxymethyl)-L-lysine gave a surface competent for binding His-tagged proteins, as demonstrated using enzyme (human dihydrofolate reductase), protein/antibody and receptor (CD36) examples. Immobilization featured chelation of copper and the His-tagged protein by the peptide monolayer, which could be recycled by removing the copper using imidazole washes prior to reuse. 相似文献
350.
We study the simple random walk on the uniform spanning tree on
\mathbb Z2{\mathbb {Z}^2} . We obtain estimates for the transition probabilities of the random walk, the distance of the walk from its starting point
after n steps, and exit times of both Euclidean balls and balls in the intrinsic graph metric. In particular, we prove that the spectral
dimension of the uniform spanning tree on
\mathbb Z2{\mathbb {Z}^2} is 16/13 almost surely. 相似文献