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61.
D. Neshev A. Dreischuh G.G. Paulus H. Walther 《Applied physics. B, Lasers and optics》2001,72(7):849-854
Numerical simulations on the evolution of step-screw and edge-screw optical phase dislocations in bulk saturable self-defocusing
nonlinear media are presented, with emphasis on their ability to induce steering waveguides for signal beams (pulses). Two
schemes for directional coupling of such signals, both ensuring a reasonable coupling-to-cross-talk efficiency ratio, are
investigated. The parameters useful for performance optimization of the couplers are discussed.
Received: 19 July 2000 / Revised version: 5 February 2001 / Published online: 27 April 2001 相似文献
62.
K. Jessen M. Bergström P. von Brentano A. Dewald B. Herskind H. Meise C. Schumacher G. Sletten O. Stuck D. Weißhaar I. Wiedenhöver J. Wrzesinski 《The European Physical Journal A - Hadrons and Nuclei》1998,2(2):113-114
An in-beam experiment with the reaction 122Sn(27Al,4np) at 127 MeV was performed at the Nordball multi-detector array in Roskilde. It provided evidence for a new high-spin
isomer in 144Sm. This isomer with T
1/2= (2.6 ± 0.5) ns at an excitation energy E
x= 9232 keV seems to belong to a family of isomers of similar configuration in neighbouring N= 82 nuclei.
Received: 16 November 1997 相似文献
63.
H. B. Jeppesen J. Byskov-Nielsen P. Wright J. G. Correia L. M. Fraile H. O. U. Fynbo K. Johnston K. Riisager 《The European Physical Journal A - Hadrons and Nuclei》2007,32(1):31-34
A possible dependence of the alpha decay process on the solid-state environment of the decaying nucleus has been investigated
by measuring the alpha-decay half-life of 221Fr at room temperature in different materials ( Au, W, Si and polyethylene). The change in half-life between the insulator
Si and the metals Au/ W is found to be 0.30(17)% / 0.42(21)%, respectivly. Furthermore an improved value of 4.79(2)min was
found for the absolute half-life of 221Fr. 相似文献
64.
G. Lhersonneau B. Pfeiffer J. Alstad P. Dendooven K. Eberhardt S. Hankonen I. Klöckl K.-L. Kratz A. Nähler R. Malmbeck J.P. Omtvedt H. Penttilä S. Schoedder G. Skarnemark N. Trautmann J. Äystö 《The European Physical Journal A - Hadrons and Nuclei》1998,1(3):285-297
The decay of 111Ru obtained from fast on-line chemical and mass separation has been investigated by β-γ-t and γ-γ coincidence techniques. Earlier spin and parity assignments of 111Rh levels based on extrapolations of level systematics are confirmed. In particular, the K=1/2 intruder band is supported
by the hindrance of E2 transitions between deformed and spherical states and enhancement of intraband E2 transitions. The
excitation energies of intruder band members in Rh isotopes show a minimum at 109Rh64, with two neutrons less than 111Rh at the N=66 midshell. This trend, which differs from the one in the higher-Z neighbouring elements Ag and Cd with minima
at N=66, follows the evolution of deformation observed in the lower-Z elements Ru and Mo.
Received: 25 June 1997 / Revised version: 10 September 1997 相似文献
65.
66.
A. Dhal R. K. Sinha P. Agarwal S. Kumar Monika B. B. Singh R. Kumar P. Bringel A. Neusser R. Kumar K. S. Golda R. P. Singh S. Muralithar N. Madhavan J. J. Das A. Shukla P. K. Raina K. S. Thind A. K. Sinha I. M. Govil P. K. Joshi R. K. Bhowmik A. K. Jain S. C. Pancholi L. Chaturvedi 《The European Physical Journal A - Hadrons and Nuclei》2006,27(1):33-36
High-spin states in 78Kr have been studied via the 63Cu (19F, 2p2n)78Kr reaction at a beam energy of 60 MeV using the Indian National Gamma Array (INGA). In this nucleus, lifetimes have been
measured upto the Iπ=22+ level in the yrast positive-parity band and upto the Iπ=15- level in the negative-parity band using the Doppler Shift Attenuation Method (DSAM). The deduced transition quadrupole moments
Qt's are found to decrease with rotational frequency for both the bands. 相似文献
67.
Benzylated pulps from sugar cane bagasse 总被引:1,自引:0,他引:1
R. PEREIRA S. P. CAMPANA FILHO A. A. S. CURVELO A. GANDINI 《Cellulose (London, England)》1997,4(1):21-31
An optimized ethanol/water process has been employed for the pulping of fibres from sugar cane bagasse. After pretreatment
with aqueous NaOH, unbleached pulps were subjected to benzylation at 110 °C for different periods of time. The resulting purified
products were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), gel permeation chromatography
(GPC) and infrared spectroscopy (IR). The results showed that benzylation proceeded to various extents depending on the reaction
time, as assessed by weight gain. During the first 3 h, a loss of mass was observed due to the occurrence of benzylation of
low molecular weight polyoses, which were eliminated in the purification step. After that period of time a drastic weight
increase was observed probably because crystalline regions had developed. The samples with low degrees of benzylation were
insoluble, whereas the more benzylated counterparts showed limited solubility in THF. Partially soluble samples and a completely
soluble one showed very different GPC elution profiles. This may be attributed to the efficiency of the pre treatment which,
in the latter case, employed more concentrated alkali. Thermogravimetric analyses showed that all samples were degraded above
310 °C. Glass transition temperatures ranged between 42 °C and 65 °C, increasing as the extent of benzylation increased
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
68.
69.
Hongxiang Teng Liang Yang Frantisek Mikes Yasuhiro Koike Yoshiyuki Okamoto 《先进技术聚合物》2007,18(6):453-457
Copolymers of methyl methacrylate (MMA) with 2,3,5,6‐tetrafluorophenyl methacrylate (TFPMA), pentafluorophenyl methacrylate (PFPMA), and 4‐trifluoromethyl‐2,3,5,6‐tetrafluorophenyl methacrylate (TFMPMA) were investigated. All the three systems showed a random copolymerization character. The composition, glass transition temperature (Tg), and refractive index of the copolymers obtained were studied. Tgs of TFPMA/MMA and PFPMA/MMA copolymers were found to deviate positively from the Gordon–Taylor equation. However, Tgs of TFMPMA/MMA copolymers were well fit with the Gordon–Taylor equation. These results indicated the existence of interaction between MMA and either TFPMA or PFPMA units in copolymers. This interaction resulted in the enhancement of the Tg of MMA polymers through the copolymerization with TFPMA and PFPMA. The refractive index and the light transmittance of copolymers were close to those of PMMA. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
70.
Ji‐Hye Jung Aruna Kumar Mohanty Jihwa Ye Taeheon Lee Junyoung Ahn Yeong‐Gweon Lim Taihyun Chang Hyun‐Jong Paik 《Journal of polymer science. Part A, Polymer chemistry》2017,55(24):4020-4026
Covalent fixed multicyclic polystyrene conformers were synthesized from inconvertible polystyrene conformers based on p‐tert‐butylthiacalix[4]arene by azidation and subsequent click coupling. Selective 1D NOESY analyses confirmed that the spatial structures of star polystyrene precursors and multicyclic polystyrenes were preserved during the azidation and click coupling processes. The conformation of star polymers affected degree of decrease in the hydrodynamic volume after cyclization but had little effect on glass transition behavior. The rigid core of star polymer increased the Tg but in the case of multicyclic polymer, this influence of core structure was reduced. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 4020–4026 相似文献