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101.
Messchendorp JG Janssen S Kotulla M Ahrens J Annand JR Beck R Bloch F Caselotti G Fog L Hornidge D Krusche B Langgärtner W McGeorge JC MacGregor IJ Mengel K Metag V Novotny R Owens RO Pfeiffer M Sack S Sanderson R Schadmand S 《Physical review letters》2002,89(22):222302
Differential cross sections of the reactions (gamma,pi(0)pi(0)) and (gamma,pi(0)pi(+/-)) have been measured for several nuclei (1H,12C, and (nat)Pb) at an incident-photon energy of E(gamma)=400-460 MeV at the tagged-photon facility at MAMI-B using the TAPS spectrometer. A significant nuclear-mass dependence of the pipi invariant-mass distribution is found in the pi(0)pi(0) channel. This dependence is not observed in the pi(0)pi(+/-) channel and is consistent with an in-medium modification of the pipi interaction in the I=J=0 channel. The data are compared to pi-induced measurements and to calculations within a chiral-unitary approach. 相似文献
102.
Particle image velocimetry (PIV) was used to measure mean flow and turbulence characteristics in the separated flow behind a rearward facing step. The confidence limits characterising estimates of mean velocity and turbulence intensity obtained by PIV are discussed. The relevance of background turbulence levels and sample size in determining these limits is considered. 相似文献
103.
A sensitive and simple assay for the detection of Pb(2+) in aqueous solutions is reported. It takes advantage of the high affinity between single-stranded DNA (ssDNA) and single-walled carbon nanotubes (SWCNT) as well as the capability of SWCNT in fluorescence quenching. Lead(II) catalyzes the cleavage of a fluorescently labeled DNA substrate by a DNAzyme, which releases the single-stranded product to be adsorbed onto a SWCNT. The decrease in fluorescence is proportional to the Pb(2+) concentration. Concentrations as low as 1 nM Pb(2+) in water could be detected and the detection range spans over 5 orders of magnitude. The unique combination of Pb-specific DNAzyme with SWCNT produces a universal, facile and cost-effective sensing platform for lead ions. The concept can be applied to the design of detection assays for other metal ions or small molecules. 相似文献
104.
L. Jendrassik L. Dziobek M. Halász Margret B. Strauss W. E. Wilins H. D. Jones F. Breh O. H. Gaebler R. Truszkowski R. L. Zwemer F. Takács K. B. Thomson W. C. Lee O. S. Duffendack F. H. Wiley J. S. Owens C. Bomskov W. S. Hoffman G. Barkan Eva Berger Rudolf Schmid E. Starkenstein H. Weden W. Lintzel M. Sahyun R. F. Felkamp J. Dabrowski L. Marchlewski J. Peregud J. Kusmina Ph. Fischer H. Straller B. Behrens H. Taeger Frida Schmitt H. J. Morris H. O. Calvery K. Hinsberg M. Kiese G. Bertrand L. Silberstein H. de Waal 《Analytical and bioanalytical chemistry》1939,117(11-12):452-464
105.
Szyszka R Hanton SD Henning D Owens KG 《Journal of the American Society for Mass Spectrometry》2011,22(4):633-640
Measuring the residual polyethylene glycol (PEG) in polyethylene oxide (PEO)-based surfactants is important to fully understanding
the performance of these materials. Traditional methods of quantitating PEG in PEO-based surfactants can be time-consuming
and struggle with low amounts or overlapping molecular mass distributions. This paper describes a matrix-assisted laser desorption/ionization
(MALDI) mass spectrometry method developed to quantitate residual PEG in a series of ethoxylated surfactants. The technique
addresses the difficulties faced in doing quantitative MALDI experiments by utilizing both internal standard and standard
additions protocols. The method produces excellent straight line standard addition plots, and the quantitative results are
verified using both a constructed standard and an independent traditional chromatographic separation. 相似文献
106.
The title complexes of general formula [Cu(HL)Cl2] or [Cu(L)Cl] were isolated from boiling EtOH. The thiosemicarbazones have
been characterized by their 1H- and 13C-n.m.r., i.r. and electronic spectra. The i.r., electronic and e.s.r. spectra of the
copper(II) complexes are compared with data on previously studied complexes. The antitumour and antiviral activities of the
thiosemicarbazones and their complexes are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
107.
[structure: see text] Oligonucleotides with novel modifications, 2'-O-[2-(amino)-2-oxoethyl] (2'-O-NAc), 2'-O-[2-(methylamino)-2-oxoethyl] (2'-O-NMAc), 2'-O-[2-(dimethylamino)-2-oxoethyl] (2'-O-DMAc), and 2'-O-[2-[[2-(dimethylamino)ethyl]amino]-2-oxoethyl] (2'-O-DMAEAc), have been synthesized. These modified oligonucleotides exhibit high binding affinity to complementary RNA (and not to DNA) and considerably enhance the nuclease stability of oligonucleotides with t(1/2) > 24 h. 相似文献
108.
Magnetic domain phases of ultrathin Fe/Ni/Cu(001) are studied using photoemission electron microscopy at the spin reorientation transition (SRT). We observe a new magnetic phase of bubble domains within a narrow SRT region after applying a nearly in-plane magnetic field pulse to the sample. By applying the magnetic field pulse along different directions, we find that the bubble domain phase exists only if the magnetic field direction is less than approximately 10 degrees relative to the sample surface. A temperature dependent measurement shows that the bubble domain phase becomes unstable above 370 K. 相似文献
109.
110.
Dihadron spectra in high-energy heavy-ion collisions are studied within the next-to-leading order perturbative QCD parton model with modified jet fragmentation functions due to jet quenching. High-p(T) back-to-back dihadrons are found to originate mainly from jet pairs produced close and tangential to the surface of the dense matter. However, a substantial fraction also comes from jets produced at the center with finite energy loss. Consequently, high-p(T) dihadron spectra are found to be more sensitive to the initial gluon density than the single hadron spectra that are more dominated by surface emission. A simultaneous chi(2) fit to both the single and dihadron spectra can be achieved within a range of the energy loss parameter E(0)=1.6-2.1 GeV/fm. Because of the flattening of the initial jet production spectra at square root s=5.5 TeV, high p(T) dihadrons are found to be more robust as probes of the dense medium. 相似文献