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831.
Burford N Spinney HA Ferguson MJ McDonald R 《Chemical communications (Cambridge, England)》2004,(23):2696-2697
[Mes*NP(DMAP)2][OTf] represents the first ligand-rich coordination complex of a phosphorus(III) Lewis acceptor, and a three coordinate hypervalent electron-rich (lone pair bearing) center; further diversification is demonstrated by, [(Mes*NP)2(4,4'-BIPY)][OTf]2, representing an acceptor-rich dication. 相似文献
832.
Wechsler D McDonald R Ferguson MJ Stradiotto M 《Chemical communications (Cambridge, England)》2004,(21):2446-2447
A new indene-based ligand featuring pendant phosphine sulfide and amine donor fragments has been developed; Rh(I) coordinates to the neutral form of the ligand in a kappa2-[N,S] fashion, while the anionic form of the ligand binds Rh(I) and Mn(I) in kappa2-[C,S] and eta5 modes, respectively. 相似文献
833.
834.
Eriksson LG Mueck A Sauter O Coda S Mantsinen MJ Mayoral ML Westerhof E Buttery RJ McDonald D Johnson T Noterdaeme JM De Vries P 《Physical review letters》2004,92(23):235004
In a tokamak fusion reactor the energetic alpha particles will transiently stabilize the magnetohydrodynamic activity causing sawtooth oscillations. The crash events terminating long sawtooth free periods can provide seed islands for neoclassical tearing modes [Phys. Rev. Lett. 88, 105001 (2002)]]. To shorten the sawtooth periods localized current drive near the q=1 surface is a possibility. This Letter provides the first experimental evidence for the effectiveness of this method in the different physics regime associated with fast-ion-induced long sawteeth on the JET tokamak. 相似文献
835.
A near-infrared diode laser with sample-grating distributed Bragg reflectors was used as a widely tunable spectroscopic source for multispecies chemical sensing. Quartz-enhanced photoacoustic spectroscopy was utilized to obtain high absorption sensitivity in a compact gas cell. CO2, H2O C2H2, and NH3 were monitored. A noise equivalent sensitivity of 8 x 10(-9) cm(-1) W(-1) Hz(-1/2)for NH3 detection was achieved, which corresponds to a NH3 mixing ratio of 4.4 parts in 10(6) by volume (ppmv) with a 1-s time constant and available 5.2-mW optical power in the gas cell. 相似文献
836.
Bennett G Gorce JP Keddie JL McDonald PJ Berglind H 《Magnetic resonance imaging》2003,21(3-4):235-241
We report magnetic resonance profiling experiments to monitor (i) the drying of alkyd emulsion layers, (ii) the cure of wood glue layers and (iii) water transport through glue lines. The alkyd drying is a two stage process. We report new results which support previous evidence that the alkyd drops do not coalesce until the water fraction is below circa 0.02. The profiles recorded from glue layers suggest that MR is a sensitive probe of the curing process and barrier properties of the glue. The measurements were made using GARField (stray field, STRAFI like) magnetic resonance profiling and an improved GARField magnet design characterized by two values of the gradient-to-field strength ratio at two locations offering the same field strength is also reported. 相似文献
837.
Ueda T Bernard GM McDonald R Wasylishen RE 《Solid state nuclear magnetic resonance》2003,24(2-3):163-183
Cobalt-59 NMR experiments have been carried out on single-crystal and polycrystalline (powder) samples of (+/-)-tris(ethylenediamine)cobalt(III) chloride trihydrate, (+/-)-[Co(en)(3)]Cl(3) x 3H(2)O, and of its dehydrate. In addition, the X-ray crystal structure of the dehydrated sample has been determined. X-ray diffraction measurements confirm a long-held assumption that dehydration has only minor effects on the structure of the [Co(en)(3)](3+) cation. Nevertheless, these small differences have a detectable effect on the 59Co nuclear magnetic resonance properties of these compounds; in particular, the nuclear quadrupole coupling constant, C(Q). Straightforward identification of the c-axis for large single crystals of (+/-)-[Co(en)(3)]Cl(3).3H(2)O and of its dehydrate allowed us to obtain single-crystal 59 Co NMR data by orienting the crystals in an MAS rotor. Data collected on single crystals and polycrystalline samples indicate that C(Q)=-3.05+/-0.05 and -2.80+/-0.05 MHz for the hydrated and dehydrated samples, respectively; the signs have been assigned on the basis of a point charge model. The chemical shift tensor principal components were also determined: for the hydrated sample, delta(perpendicular)=7281+/-2 ppm, delta(parallel)=7004+/-4 ppm and delta(iso)=7189 ppm; for the dehydrated sample, delta(perpendicular)=7288+/-2 ppm, delta(parallel)=7008+/-4 ppm and delta(iso)=7195 ppm. The electric field gradient and chemical shift tensors are axially symmetric, as required by crystal symmetry. 相似文献
838.
OBJECTIVE: This study aimed to explore some factors influencing perceptions of human gene therapy. METHOD: A small qualitative study using two semi-structured interviews per participant (n = 22). The groups comprised (1) people with cystic fibrosis and members of their family (n = 9), and (2) students from a science evening class as well as lay members of the public selected from the practice list of a local general practitioner (n = 13). RESULTS: This pilot study demonstrates support for somatic gene therapy and ambivalence about germline gene therapy. A clear distinction is drawn between therapy and enhancement, with the majority opposing gene enhancement. CONCLUSIONS: Attitudes towards the acceptability of gene therapy are not necessarily determined by experience of, or exposure to, a genetic condition. More research is needed with the general public to determine what is perceived to be acceptable public policy in this field. 相似文献
839.
Formaggio JA Yu J Adams T Alton A Avvakumov S de Barbaro L de Barbaro P Bernstein RH Bodek A Bolton T Brau J Buchholz D Budd H Bugel L Conrad JM Drucker RB Fleming BT Foster J Frey R Goldman J Goncharov M Harris DA Johnson RA Kim JH Koutsoliotas S Lamm MJ Marsh W Mason D McDonald J McFarland KS McNulty C Naples D Nienaber P Romosan A Sakumoto WK Schellman HM Shaevitz MH Spentzouris P Stern EG Suwonjandee N Vakili M Vaitaitis A Yang UK Zeller GP Zimmerman ED 《Physical review letters》2001,87(7):071803
The NuTeV experiment at Fermilab has used a sign-selected neutrino beam to perform a search for the lepton number violating process nu(mu)e(-)-->mu(-)nu(e), and to measure the cross section of the standard model inverse muon decay process nu(mu)e(-)-->mu(-)nu(e). NuTeV measures the inverse muon decay asymptotic cross-section slope sigma/E to be (13.8 +/- 1.2 +/- 1.4) x 10(-42) cm(2)/GeV. The experiment also observes no evidence for lepton number violation and places one of the most restrictive limits on the cross-section ratio sigma(nu(mu)e(-)-->mu(-)nu(e))/sigma(nu(mu)e(-)-->mu(-)nu(e)) < or = 1.7% at 90% C.L. for V-A couplings and < or = 0.6% for scalar couplings. 相似文献
840.
Thomas L. McDonald 《Microchemical Journal》1982,27(1):124-126
We have designed a microcell for use in the dialysis of microliter sample volumes. The microcell was easily constructed from inexpensive laboratory materials and allowed for a rapid buffer exchange with total protein recovery. 相似文献