排序方式: 共有31条查询结果,搜索用时 15 毫秒
21.
Ahonen P.P. Moisala A. Tapper U. Brown D.P. Jokiniemi J.K. Kauppinen E.I. 《Journal of nanoparticle research》2002,4(1-2):43-52
We have investigated the development of crystal morphology and phase in ultrafine titanium dioxide particles. The particles were produced by a droplet-to-particle method starting from propanolic titanium tetraisopropoxide solution, and calcined in a vertical aerosol reactor in air. Mobility size classified 40-nm diameter particles were conveyed to the aerosol reactor to investigate particle size changes at 20–1200°C with 5–1-s residence time. In addition, polydisperse particles were used to study morphology and phase formation by electron microscopy. According to differential mobility analysis, the particle diameter was reduced to 21–23-nm at 600°C and above. Precursor decomposition occurred between 20°C and 500°C. The increased mobility particle size at 700°C and above was observed to coincide with irregular particles at 700°C and 800°C and faceted particles between 900°C and 1200°C, according to transmission electron microscopy. The faceted anatase particles were observed to approach a minimized surface energy by forming {101} and {001} crystallographic surfaces. Anatase phase was observed at 500–1200°C and above 600°C the particles were single crystals. Indications of minor rutile formation were observed at 1200°C. The relatively stable anatase phase vs. temperature is attributed to the defect free structure of the observed particles and a lack of crystal–crystal attachment points. 相似文献
22.
C. Daum L.O. Hertzberger W. Hoogland R. Jongerius J.C. Kluyver G. Polok W. Spierenburg H. Tiecke L. Wiggers D.G. Bardsley J. Malos R.J. Tapper R.J. Whyley M. Bosman M. Cerrada V. Chabaud B. Hyams J. Vermeulen F. Wickens 《Physics letters. [Part B]》1981,100(5):439-442
A search for the S(1936) has been made in the invariant mass spectrum of p?p-pairs produced inclusively in proton-beryllium interactions at 100 GeV incident momentum. No enhancement is observed, giving a 3 standard deviation upper limit on the cross section of 220 nb/nucleon for production of a narrow p?p state around ≈ 1940 MeV in the xF range 0.18 <xF<0.48. 相似文献
23.
R. Bailey E. R. Belau T. Böhringer M. Bosman V. Chabaud C. Damerell C. Daum H. Dijkstra S. Gill A. Gillman R. S. Gilmore Z. Hajduk C. Hardwick W. Hoogland B. D. Hyams J. Kemmer R. Klanner U. Kötz S. W. L. Kwan G. Lütjens G. Lutz J. Malos W. Männer E. Neugebauer H. Palka M. Pepe J. Richardson G. de Rijk M. Rozanska K. Rybicki H. Seebrunner U. Stierlin R. J. Tapper H. G. Tiecke M. Turala G. Waltermann P. Weilhammer F. Wickens L. W. Wiggers A. Wylie T. Zeludziewicz 《Zeitschrift fur Physik C Particles and Fields》1985,28(3):357-363
24.
H. Dijkstra R. Bailey E. Belau T. Böhringer M. Bosman V. Chabaud C. Damerell C. Daum G. de Rijk S. Gill A. Gillman R. Gilmore Z. Hajduk C. Hardwick W. Hoogland B. Kisielewski B. D. Hyams R. Klanner S. Kwan U. Kötz G. Lütjens G. Lutz J. Malos W. Männer E. Neugebauer H. Palka M. Pepé J. Richardson K. Rybicki H. J. Seebrunner U. Stierlin R. J. Tapper H. G. Tiecke M. Turala G. Waltermann S. Watts P. Weilhammer F. Wickens L. W. Wiggers A. Wylie T. Zeludziewicz ACCMOR Collaboration 《Zeitschrift fur Physik C Particles and Fields》1986,31(3):375-389
Inclusive ? meson production has been measured for 100 GeV/c and 200 GeV/c incident π?, \(\bar p\) andK ?, and for 120 GeV/c and 200 GeV/c incident π+,p andK +, using a Be target. A total of 630,000 ? mesons has been recorded in the kinematic range 0<x F <0.4. Presented are the differential cross sectionsdσ/dx F anddσ/dp T 2. The longitudinal momentum distributions show that the strange valence quarks of the incidentK mesons play an important role in ? meson production, even at smallx F . The decay angular distribution of the ? meson is evaluated in the Gottfried-Jackson frame and is expressed in the elements of the density matrix. There is a small but significant cos2 θ GJ dependence for smallp T , which decreases for increasingp T . 相似文献
25.
H. Dijkstra R. Bailey E. Belau T. Böhringer M. Bosman V. Chabaud C. Damerell C. Daum G. de Rijk S. Gill A. Gillman R. Gilmore Z. Hajduk C. Hardwick W. Hoogland B. D. Hyams R. Klanner S. Kwan U. Kötz G. Lütjens G. Lutz J. Malos W. Manner E. Neugebauer H. Palka M. Pepé J. Richardson K. Rybicki H. J. Seebrunner U. Stierlin R. J. Tapper H. G. Tiecke M. Turala G. Waltermann S. Watts P. Weilhammer F. Wickens L. W. Wiggers A. Wylie T. Zeludziewicz ACCMOR Collaboration 《Zeitschrift fur Physik C Particles and Fields》1986,31(3):391-399
The parton fusion model is used to describe the longitudinal differential cross section (dσ/dx F ) of hadronic ? production. Thedσ/dx F for ? production in π± p, \(\mathop p\limits^{( - )} p\) andK ± p interactions is evaluated in the model by using structure functions for the constituents of the interacting particles. A comparison between the model and high statistics data in the Feynmanx range 0.0<x F (?)<0.4 allows the determination of the strange valence quark distribution inK mesons and the strange sea quark distribution in π mesons, which appears to be harder than the light sea quark distribution. The comparison also shows that a significant part of inclusive ? production is due to the OZI allowed fusion of strange quarks, while the OZI inhibited fusion diagrams are strongly suppressed. 相似文献
26.
C. Daum L. O. Hertzberger W. Hoogland R. T. Jongerius G. Polok W. Spierenburg H. G. Tiecke L. W. Wiggers D. G. Bardsley J. Malos R. J. Tapper R. J. Whyley M. Bosman M. Cerrada V. Chabaud B. Hyams J. C. Vermeulen P. Weilhammer A. Wylie A. Dwuraźny Z. Hajduk M. Rózańska K. Rybicki M. Turala G. Blanar W. Blum H. Dietl W. Faissler L. Görlich R. Klanner E. Lorenz G. Lütjens G. Lutz W. Männer A. Pugl T. W. L. Sanford U. Stierlin R. Bailey C. Damerell D. Giddings A. Gillman C. Harwick P. Sharp F. Wickens The ACCMOR Collaboration 《Zeitschrift fur Physik C Particles and Fields》1982,13(4):273-276
The reactionpBe→Λ(1,520)X has been measured at 100 GeV incident momentum in the kinematic range 0.15<x<0.35 \((x = 2p_\parallel ^{c.m} /\sqrt s )\) andP T <1 GeV. The invariant cross section is compatible with that measured forpp interactions at the CERN-ISR. The differential cross sectiondσ/dp T 2 is fitted to an exponentiale ?αp T 2 with α=2.7 GeV?2. 相似文献
27.
On the Chemistry of Kanemite [NaHSi2O5 · 3 H2O]x Starting from δ-Na2Si2O5 Kanemit was prepared by a direct exchange of Na+ by H+ in water containing reaction mixtures. By 29Si-, 23Na- and 1H-MAS-NMR investigations Kanemit was characterized as a layersilicate [NaHSi2O5 · 3 H2O]. By thermal treatment as well as by dehydration at room temperature under vacuum conditions a monohydrate is formed in which the layerstructure remains nearly unchanged. At temperatures between 100 and 110°C under normal conditions a hydrate phase of the composition [NaHSi2O5 · 0.25 H2O]x is prepared in which a changed silicate-layerstructure exists. 相似文献
28.
Peter Paetzold Ulli Englert Rudolf Finger Thomas Schmitz Alexander Tapper Ralf Ziembinski 《无机化学与普通化学杂志》2004,630(4):508-518
The addition of Lewis bases L to the methyl(methylidene)boranes MeB=CA2(A = SiMe3) and MeB=CAA′ (A′ = SiMe2Cl) gives the adducts MeB(L)=CA2 ( 1a , b ; L = trimethylpyridine, PMe3) and MeB(L)=CAA′ ( 1c , d ; L = di‐ and trimethylpyridine), respectively. Alcohols and amines HX are added to the BC double bond to give boranes MeB(X)—CHA2 ( 8a — c ; X = OiPr, OtBu, NiPr2); MeB=CAA′ and HNMe2 react in the ratio 1:2, yielding MeB(X)—CHA(SiMe2X) ( 2d ; X = NMe2). From MeB=CA2 and BH3, the five‐membered ring [—CA2—BH—CA2—BMe(Hm)2BMe—] ( 2e ; 2:1) or the six‐membered ring [—CA2—BH(Hμ)2BMe—CA2—BH(Hμ)2BMe—] ( 2f ; 1:1) are formed, both containing double hydrogen bridges; the product 2f crystallizes in the space group P1¯. The metallocene trihydrides [Cp2MH3] add to the BC double bond under formation of a double hydrogen bridge to give [Me(A2CH)B(Hμ)2MCp2] ( 2g , h ; M = Nb, Ta). MeB=CA2 can be chloroborated, ‐stannated, and ‐phosphated with E—Cl to yield the boryldisilylmethanes MeB(Cl)—CA2—E ( 2i — l ; E = EtClB, tBuClB, Me2ClSn, Cl2P). The alkyloboration and ‐alumination with E—R leads to the boryldisilylmethanes MeBR—SiA2—E ( 2m — o ; E—R = Me2B—Me, Et2B—Et, Cl2Al—Et) and the bromination to MeB(Br)—CA2Br. (2+2) Cycloadditions are achieved, when MeB=CA2 is reacted with unsaturated molecules a=b, yielding four‐membered rings [—BMe—CA2—b—a—] [ 4a — d ; a=b = fluorenone, bis(methoxycarbonyl)ethyne (reacting at both of the C=O bonds), phenylisocyanate (reacting at the C=O bond), N‐isopropylacetoneimine], or with triple bond systems RC≡Z, yielding four‐membered rings [—BMe—CA2—Z=CR—] ( 4e — g ; RC≡Z = PhC≡CPh, AC≡CCl, tBuC≡P). With a series of six molecules with an element‐oxygen double bond, a primary (2+2) cycloaddition is followed by a metathetical splitting of the transient four‐membered rings 4h — m . One of the metathesis products is MeB≡O, which is identified as boroxene (MeBO)3, the other component is an alkene RR′C=CA2 [starting from MeB=CA2 and PhCHO, PhC(Me)O] or an alkene RR′C=CAA′ (starting from MeB=CAA′ and PhCHO, tBuCHO) or the methylidene phosphorane Ph3P=CA2 (starting from MeB=CA2 and Ph3PO) or the dicarbadicobaltatetrahedrane [(CA)2{Co(CO)3}2] {starting from MeB=CA2 and [Co2(CO)8]}. The (2+3) cyclodaddition of MeB=CA2 to the azide X2PN3 (X = NiPr2) as 1, 3‐dipole gives the five‐membered ring [=BMe—CA2—N=N—NX=] ( 5a ) and to RN3 the rings [=BMe—CA=N—NA—NR=] ( 5′b , c ; R = iBu, A; formed from the cycloadducts 5b , c by migration of A); analogously, [=BMe—CA′=N—NA—NA=] ( 5′d ) is formed from MeB=CAA′ and AN3. Finally, the nitrone O—NMe=CHPh and MeB=CA2 or MeB=CAA′ give the corresponding (2+3) cycloadducts 5e , f , respectively. All of the products were characterized by their 1H, 11B, and 13C NMR spectra. 相似文献
29.
H. Dijkstra R. Bailey E. Belau T. Böhringer M. Bosman V. Chabaud C. Damerell C. Daum G. de Rijk S. Gill A. Gillman R. Gilmore Z. Hajduk C. Hardwick W. Hoogland B. D. Hyams R. Klanner S. Kwan U. Kötz G. Lütjens G. Lutz J. Malos W. Männer E. Neugebauer H. Palka M. Pepé J. Richardson K. Rybicki H. J. Seebrunner U. Stierlin R. J. Tapper H. G. Tiecke M. Turala G. Waltermann S. Watts P. Weilhammer F. Wickens L. W. Wiggers A. Wylie T. Zeludziewicz 《Zeitschrift fur Physik C Particles and Fields》1986,32(3):349-351
Experimental results on inclusive ? production are compared with the Lund model for lowp T hadronic interactions. The data is based on a sample of 600,000 ? mesons in the kinematic rangep T <1.0 (GeV/c)2 and 0.0<x F<0.4, produced in π±,K ±,p and \(\bar p\) Be interactions at 100 GeV/c and 120 GeV/c incident momentum. The Lund model reproduces the shapes of the longitudinal differential cross sections reasonably well, but the relative cross sections for incident, π,K andp show a discrepancy with the data. 相似文献
30.
Anna Lähde Noora Kokkonen Antti J. Karttunen Sirpa Jääskeläinen Unto Tapper Tapani A. Pakkanen Jorma Jokiniemi 《Journal of nanoparticle research》2011,13(9):3591-3598
Atmospheric pressure chemical vapor synthesis was used to produce copper nanoparticle composites in an amorphous silicon dioxide,
i.e., either copper nanoparticles coated with amorphous silicon dioxide or copper nanoparticles embedded in amorphous silicon
dioxide matrix. Synthesized metal–organic copper(I) complex was used as a precursor that provided well-defined ratio (1:2)
of copper and silicon. The thermal decomposition of the Cu(I) complex molecule leads to homogenous nucleation and formation
of copper nanoparticles which are subsequently coated with Si/SiO2 in the gas phase. The decomposition was greatly enhanced when reductive atmosphere, i.e., H2/N2 10 v% were used instead of pure nitrogen. A narrow size distribution with the geometric mean diameter of the particle agglomerates
around 30 nm was observed while the primary size of the copper core particles was around 5 nm. 相似文献