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1.
2.
Hornstein MK Bajaj VS Griffin RG Temkin RJ 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2006,34(3):524-533
We report the regulated continuous-wave (CW) operation of a second harmonic gyrotron oscillator at output power levels of over 8 W (12.4 kV and 135 mA beam voltage and current) in the TE(0,6,1) mode near 460 GHz. The gyrotron also operates in the second harmonic TE(2,6,1) mode at 456 GHz and in the TE(2,3,1) fundamental mode at 233 GHz. CW operation was demonstrated for a one-hour period in the TE(0,6,1) mode with better than 1% power stability, where the power was regulated using feedback control. Nonlinear simulations of the gyrotron operation agree with the experimentally measured output power and radio-frequency (RF) efficiency when cavity ohmic losses are included in the analysis. The output radiation pattern was measured using a pyroelectric camera and is highly Gaussian, with an ellipticity of 4%. The 460-GHz gyrotron will serve as a millimeter-wave source for sensitivity-enhanced nuclear magnetic resonance (dynamic nuclear polarization) experiments at a magnetic field of 16.4 T. 相似文献
3.
In this paper we show a number of natural geometric optimization problems in the plane to becomplete for a classD
P
. The classD
p
contains both NP and Co-NP and is contained in
2
P
=P
NP. Completeness inD
p
is exhibited under many-one and positive reductions. Further anOptP(O(logn)) result is also obtained for some of these optimization problems.Work on this paper by the first author was supported in part by NSF Grant No. MIP 85-21356 and ARO Contract No. DAAG29-85-C-0018 under Cornell/MSI. Work by the second author was supported in part by NSF Grant No. DCR 86-06366 at Ohio State and ONR Grant No. N00014-k-0045 at Harvard.On leave from Ohio State University. 相似文献
4.
A single crystal X-ray analysis has confirmed the constitution and established the stereochemistry of the triterpene, malabaricol. 相似文献
5.
Ashok G. Bajaj Sukh Dev Edward Arnold Bruce Tagle Jon Clardy 《Tetrahedron letters》1981,22(46):4623-4626
The steroechemistry of guggulsterol-1, a component of the exudate of , is shown to be 20(R), 22(R)(). 相似文献
6.
General indole C3 reductive alkylation conditions have been developed. The scope of this reaction includes C2 unsubstituted indoles, aryl and alkyl aldehydes, as well as N-H and N-alkyl indole substrates. 相似文献
7.
Yinghong Sheng Jerzy Leszczynski Thuc-Quyen Nguyen Anu Bamgbelu 《Structural chemistry》2007,18(6):827-832
A theoretical study using density functional theory was performed to understand the structure/property relationship of the
cationic conjugated polyelectrolytes, poly[9,9-bis-(6′-N,N,N-trimethylammonium) hexyl] fluorene-alt-4,7-(2,1,3-benzothiadiazole)] (PFBT-X, where X = Br). The torsion angle between the fluorene and benzothiadiazole units in the PFBT monomer was found to substantially affect
the structural and electronic properties of the cationic PFBT monomer. The changes of geometrical parameter, HOMO and LUMO energy levels, and band gap, as well as the absorption maximum
are discussed in terms of the torsion in the PFBT monomer structure. For comparison, its neutral analogue, the monomer of
poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) (F8BT) was also studied. The length of conjugation backbone was also examined. 相似文献
8.
Summary A colorimetric method for the determination of 2,2-dihydroxy-biphenyl in rat urine is described. The ether extract is subjected to thin-layer chromatography on silica gel-G plates in the solvent system benzene-methanol (8020) and spots corresponding to 2,2-dihydroxybiphenyl and its glucuronide derivative are eluted with ethanol. The glucuronide is hydrolysed with HCl and the 2,2-di-hydroxybiphenyl content is determined after colour development with sodium cobaltinitrite, the absorbance being read at 410 nm. The method is sensitive and reproducible. It obeys the Lambert-Beer law in the concentration range 0.7–8.9g/ml.
Eine empfindliche kolorimetrische Methode zur Bestimmung von 2,2 -Dihydroxybiphenyl
Zusammenfassung Eine kolorimetrische Methode zur Bestimmung von 2,2-Dihydroxy-biphenyl in Rattenharn wurde beschrieben. Der ätherische Extrakt wird auf Silikagel-G-Platten dünnschicht-chromatographisch mit dem Lösungsmittelsystem Benzol-Methanol (8020) getrennt. Die dem genannten Stoff und seinem Glucuronid entsprechenden Flecken werden mit äthanol eluiert. Das Glucuronid wird mit Salzsäure hydrolysiert und der Gehalt an 2,2-Di-hydroxybiphenyl nach Ausführung der Farbreaktion mit Natriumkobalti-nitrit und Messung bei 410 nm bestimmt. Das Verfahren ist empfindlich und gut reproduzierbar. Es entspricht dem Lambert-Beerschen Gesetz zwischen 0,7 und 8,9g/ml.相似文献
9.
Ghosh S Krishnan A Das PK Ramakrishnan S 《Journal of the American Chemical Society》2003,125(6):1602-1606
The critical micelle concentration (CMC) of several surfactants that contain an NLO chromophore, either at the hydrocarbon tail, or at the hydrophilic headgroup, or even as a counterion, was determined by hyper-Rayleigh scattering (HRS). In all cases, the HRS signal exhibited a similar variation with surfactant concentration, wherein the CMC is inferred from a rather unprecedented drop in the signal intensity. This drop is attributed to the formation of small pre-micellar aggregates, whose concentrations become negligible above CMC. In addition, a probe molecule, which upon protonation yielded a species with significantly enhanced HRS intensity, was developed and its utility for the determination of the CMC of simple fatty acids was demonstrated. 相似文献
10.