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31.
Shoaib Ahmad 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(3):309-318
The mechanisms and processes of the formation of the regenerative soot in a graphite hollow cathode discharge that produces
and emits carbon clusters are presented. Mass spectrometry with a specially designed E×B velocity filter analyzes the entire range of the charged clusters from C
1 to ∼C
4300. The state of the carbon vapour within the source is evaluated by using the characteristic line emissions from the carbonaceous
discharge whose formative mechanisms depend upon the kinetic and potential sputtering of the sooted cathode. The carbonaceous
discharge generates atomic and ionic C and its clusters C
m (m≥ 2), noble gas metastable atoms and ions, energetic electrons and photons in the cavity of the graphite hollow cathode. The
parameters of soot formation and its recycling depend critically on the discharge parameters, the geometry of the hollow cathode
and 3D profile of the cusp magnetic field contours.
Received 2nd July 2001 and Received in final form 10 September 2001 相似文献
32.
33.
Methotrexate (MTX) has been convalently attached to an IgG-type monoclonal antibody (791T/36) directed to tumour-associated antigen gp72. Conjugates were synthesized by the active ester method using MTX N-succinimidyl ester at various pH values (7.5-10.5). Following purification by gel filtration, high performance liquid chromatography was used to assess the free drug or its derivatives in samples of MTX-791T/36 conjugates previously treated (or not) with hydroxylamine. Quantitative analysis, performed on a reversed phase column (pore size 300 A) with isocratic acetonitrile-sodium acetate buffer (pH 4.8) as mobile phase, indicated no detectable amount of free methotrexate in hydroxylamine-treated conjugates even six months after their preparation. Similar observations were made with conjugates, whose synthesis were performed at pH greater than or equal to 10. In contrast, the presence of increasing amounts of drug/metabolite could be demonstrated in samples produced at lower pH values. Based on these findings, the pH-dependent kinetics of MTX release has been determined and used to design conditions under which stable MTX-791T/36 conjugates could be prepared without hydroxylamine reaction. 相似文献
34.
N. Ahmad C. Nanjundayya W. G. Chace M. A. Ssobolew M. M. Tschilikin A. T. Iwanowa F. Kalmanowitsch A. Kolotyrewa C. F. Cross E. J. Bevan A. Eavenson J. W. Creely J. H. Skinkle O. Viertel A. J. Hall W. N. Udalskaja D. A. Clibbens A. H. Little Karin Schulze S. M. Edelstein E. Lindemann F. Schütz W. Klauditz P. Winterfeld F. H. Guernsay L. T. Howells F. Schroeder R. Finlay G. Hasse Niederhauser H. Ris R. D. Nutting W. Lesnianski F. Fabrowicz und Coch 《Fresenius' Journal of Analytical Chemistry》1938,115(1-2):51-57
Ohne Zusammenfassung 相似文献
35.
Tokeer Ahmad Kandalam V. Ramanujachary Samuel E. Lofland Ashok K. Ganguli 《Journal of Chemical Sciences》2006,118(6):513-518
Nanoparticles of complex manganites (viz. LaMnO3, La0.67Sr0.33MnO3 and La0.67Ca{0.33}MnO3) have been synthesized using the reverse micellar route. These manganites are prepared at 800‡C and the monophasic nature
of all the oxides has been established by powder X-ray diffraction studies. TEM studies show an average grain size of 68,
80 and 50 nm for LaMnO3, La0.67Sr0.33MnO3 and La0.67Ca{0.33}MnO3respectively. Ferromagnetic ordering is observed at around 250 K for LaMnO3, 350 K for La0.67Sr0.33MnO3 and 200 K for La0.67Ca{0.33}MnO3. These Curie temperatures correspond well with those reported for bulk materials with similar composition. 相似文献
36.
Sulaiman Wadi Harun Nizam Tamchek Mohd Kamil Abd-Rahman Prabakaran Poopalan Harith Ahmad 《Optical Review》2003,10(3):133-135
A multiwavelength Brillouin/erbium fibre laser (BEFL) which operates in the long wavelength (L-band) region is demonstrated for potential applications in an L-band wavelength division multiplexing (WDM) communication system. The laser configuration consists of a long erbium-doped fibre to enable L-band amplification where two 3-dB couplers take a portion of the generated BEFL signal and re-inject it into the single mode fibre to seed a cascaded BEFL line in the same direction as the first BEFL line. A stable and strong laser comb of up to five lines with 10-GHz spacing has been obtained with a Brillouin pump (BP) of 9.2 mW and a 980 nm pump of 92 mW. The BEFL has shown a broad tuning range with a tuning characteristic for line #1 which is flat over a range greater than 9.9 nm. 相似文献
37.
Recoil proton tracks in nuclear emulsion are counted by scanning them using strip, square or circular field of view of optical microscope. In this paper, the overestimate due to the edge effects in counting recoil proton tracks at different neutron energies produced from the T(d,n)4He reaction has been determined by measuring the true track density in NTA film. The overestimate has also been calculated using the measured value of the mean projected track length (L) in the film. The percentage of measured overestimates has been compared with those obtained by calculation and the results agree reasonably well. Fading effect in NTA film has been studied and found to be 22% more in the summer than in the winter season. A great reduction in fading rate could be achieved if the films are desiccated and sealed in highly pure dry nitrogen maintained at an over-pressure of 1000 Pa to reduce water vapour ingress. After the edge effect correction, the sensitivity of NTA film has been calculated from (1.72±0.08)×10−3 tracksn−1 to (1.97±0.16)×10−3 tracksn−1 in the neutron energy ranges from 15.91 to 18.88 MeV. The response was found to be from 0.24±0.02 trackscm−2 permSv to 0.26±0.01 trackscm−2 permSv in the same energy range. 相似文献
38.
R. U. Khan P. Chakrabarti B. B. Pal 《Applied Physics A: Materials Science & Processing》1987,42(4):303-309
Large signal characterisation of double heterostructure DDR Impatt diode has been carried out in the millimeter-wave range considering the MITATT mode of operation. The structure of the device is p+-p2-p1-n1-n2-n+ where impact ionisation and tunneling takes place in the p1-n1 region. In this study we have considered two well-known heterostructures, e.g., InP/GaInAs/InP and InP/InGaAsP/InP and one nonconventional structure GaAs/InP/GaAs. The theoretical results of the performances of these devices as regards of output power, efficiency, and negative conductance revealed that the structures are quite promising as the source of power in the millimeter-wave range. The analysis may be used for other mm wave DDR heterostructure Impatts. 相似文献
39.
Multicharacteristic critical components exist in many systems. Such components could be a part of an aircraft, space shuttle or a gas ignition system. A component is critical if it causes disaster or a very high cost upon failure. In this paper, a new inspection plan for critical multicharacteristic components is presented. A mathematical model that depicts the plan is developed. An algorithm is proposed for finding the optimal number of repeat inspections and the sequence of characteristics for inspection that minimizes expected total cost per accepted component. The expected cost consists of the cost of inspection and the cost of misclassifications. The inspection plan and the model developed generalize existing models in the literature and provide a more realistic formulation. An example is given to demonstrate the plan and the model. 相似文献
40.
Phase Transitions in the Early Universe with Negatively Induced Supergravity Cosmological Constant 下载免费PDF全文
EL-NABULSI Ahmad Rami 《中国物理快报》2006,23(5):1124-1127
We consider that the observable cosmological constant is the sum of the vacuum (Avac) and the induced term (Aind - 3m^2/4) with m being the ultra-llght masses (≈ Hubble parameter) implemented in the theory from supergravities arguments and non-minimal coupling. In the absence of a scalar buildup of matter fields, we study its effects on spontaneous symmetry breaking with a Higgs potential and show how the presence of the ultra-light masses yields some important consequences for the early universe and new constraints on the Higgs and electroweak gauge bosons masses. 相似文献