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1.
In this paper we highlighted the synthesis, characterization, and practical exploitation of different types of polyphosphazenes substituted with fluorinated groups. There are several ways in which fluorine atoms can be inserted into polyphosphazenes, all of which leading to different polymers showing a wide range of characteristics. In general it is true that the insertion of fluorine atoms into phosphazene macromolecules leads to an enhancement of the thermal stability, flame resistance, low-temperature elastomericity, and chemical inertness of the phosphazenes obtained. The contribution of Italian research groups to the preparation and exploitation of organic commercial macromolecules grafted onto fluorinated polyphosphazenes is also reviewed. 相似文献
2.
3.
Roberta Seraglia Pietro Traldi Roberta Bertani Giacomo Facchin Luciano Pandolfo 《Journal of mass spectrometry : JMS》1994,29(11):619-624
A fast atom bombardment (FAB) mass spectrometric study on the open-chain compound 1,3-bis(cyanomethylenetriphenylphosphorane)propane-1,3-dione and on the cyclic zwitterionic compounds 4-oxy-5-triphenylphosphonium-6-methyl-2-pyrone and 4-oxy-5-triphenylphosphonium-6-phenyl-2-pyrone, obtained by reaction of carbon suboxide, C3O2, with stabilized phosphorus ylides, Ph3PCHX (X?CN, COMe, COPh), is described. The FAB mass spectrometric behaviour of these compounds is compared with that shown by tri-phenylphosphoranilideneketene, Ph3P ? C ? C ? O, and by 4-hydroxy-6-methyl-2-pyrone, with the aid of metastable ion data and collision spectroscopy. 相似文献
4.
Laura Bertani 《Journal of Geometry》1980,15(2):158-169
In this paper,suggested by André's papers ([2), [3]), we construct geometrical structures (X,?,//}) where X is a finite set of points, ? is a set of lines, and // is an equivalence relation on ?. These constructions are made starting with a finite and not empty set X and a permutation group G which is 2-transitive on X and such that the stabilizer of two distinct points of X is different from the identical subgroup. We look for conditions such that the structure (X, ?) is a (3,q)-Steiner system. We remember that a (3,q)-Steiner system is a pair (X,B), where X is a set of elements (called points), B is a system of subsets of X (called blocks), such that:
- every block contains q points exactly;
- given three distinct points x,y,z of X, there is exactly one subset of X belonging to B and containing x,y,z.
5.
Fabio RD Alvaro G Bertani B Donati D Giacobbe S Marchioro C Palma C Lynn SM 《The Journal of organic chemistry》2002,67(21):7319-7328
To prepare in multigram scale new antagonists of the glycine binding site associated to the NMDA receptor, an efficient distereoselective route was set up. The addition of suitable allyltin reagents to chiral N-aryl alpha-imino esters (R-(+)-tert-butyl lactate used as chiral auxiliary), gave the corresponding alpha amino acid-type derivative in high chemical yield and optical purity. This allylation reaction represents a novel example of efficient long-range stereodifferentiation process. In the last part of the synthesis, a regioselective Heck-type cyclization reaction enabled preparation of the target tetrasubstituted exocycle and trisubtituted endocycle double bond derivatives. 相似文献
6.
Agnello M Beer G Benussi L Bertani M Bianco S Botta E Bressani T Busso L Calvo D Camerini P Cerello P Dalena B De Mori F D'Erasmo G Di Santo D Fabbri FL Faso D Feliciello A Filippi A Filippini V Fiore EM Fujioka H Gianotti P Grion N Lucherini V Marcello S Maruta T Mirfakhrai N Morra O Nagae T Olin A Outa H Pace E Palomba M Pantaleo A Panzarasa A Paticchio V Piano S Pompili F Rui R Simonetti G So H Tomassini S Toyoda A Wheadon R Zenoni A;FINUDA Collaboration 《Physical review letters》2005,94(21):212303
We have searched for a deeply bound kaonic state by using the FINUDA spectrometer installed at the e(+)e(-) collider DAPhiNE. Almost monochromatic K(-)'s produced through the decay of phi(1020) mesons are used to observe K(-) absorption reactions stopped on very thin nuclear targets. Taking this unique advantage, we have succeeded to detect a kaon-bound state K(-)pp through its two-body decay into a Lambda hyperon and a proton. The binding energy and the decay width are determined from the invariant-mass distribution as 115(+6)(-5)(stat)(+3)(-4)(syst) MeV and 67(+14)(-11)(stat)(+2)(-3)(syst) MeV, respectively. 相似文献
7.
A new scanner for infrared reflectography of ancient paintings is described. The system is based on an InGaAs focal plane array which automatically scans the image plane of a lens for wide format photography. The device is compact, portable and fast for use in situ. 相似文献
8.
Ablikim M Achasov MN An L An Q An ZH Bai JZ Baldini R Ban Y Becker J Berger N Bertani M Bian JM Boyko I Briere RA Bytev V Cai X Cao GF Cao XX Chang JF Chelkov G Chen G Chen HS Chen JC Chen ML Chen SJ Chen Y Chen YB Cheng HP Chu YP Cronin-Hennessy D Dai HL Dai JP Dedovich D Deng ZY Denysenko I Destefanis M Ding Y Dong LY Dong MY Du SX Duan MY Fan RR Fang J Fang SS Feldbauer F Feng CQ Fu CD Fu JL Gao Y Geng C Goetzen K Gong WX Greco M Grishin S Gu MH Gu YT Guan YH Guo AQ Guo LB Guo YP Hao XQ 《Physical review letters》2010,105(26):261801
The decays ψ'→γπ(0), γη and γη' are studied using data collected with the BESIII detector at the BEPCII e(+)e(-) collider. The processes ψ'→γπ(0) and ψ'→γη are observed for the first time with signal significances of 4.6σ and 4.3σ, respectively. The branching fractions are determined to be B(ψ'→γπ(0))=(1.58±0.40±0.13)×10(-6), B(ψ'→γη)=(1.38±0.48±0.09)×10(-6), and B(ψ'→γη')=(126±3±8)×10(-6), where the first errors are statistical and the second ones systematic. 相似文献
9.
Synergism between flame retardant and modified layered silicate on thermal stability and fire behaviour of polyurethane nanocomposite foams 总被引:2,自引:0,他引:2
M. Modesti A. Lorenzetti S. Besco D. Hrelja S. Semenzato R. Bertani R.A. Michelin 《Polymer Degradation and Stability》2008,93(12):2166-2171
Synergy in flame retardancy of polyurethane foams between phosphorus-based flame retardant (aluminium phosphinate) and layered silicates has been investigated. We used pristine montmorillonite as well as ammonium modified clay (commercially available) and diphosphonium modified clay, which were synthesised by the intercalation of the quaternary diphosphonium salt according to a procedure reported here. The morphology of the foams was characterised through X-ray diffraction (XRD), while thermal properties were characterised by oxygen index test, cone calorimeter and thermogravimetric analysis (TGA). The morphological characterisation showed that pristine and diphosphonium modified clays are almost slightly intercalated, while ammonium modified one is very well dispersed. The results of thermal characterisation showed that in the presence of phosphinate enhancements of oxygen index, fire behaviour, measured by cone calorimeter, and thermal stability have been achieved. Phosphinate is therefore an efficient flame retardant for polyurethane foams and its flame retardancy action takes place in both condensed and gas phases. Pristine and ammonium modified layered silicate bring some enhancements of thermal stability while having no important effect in decreasing peak heat release rate (PHRR) and total heat evolved (THE) when used in conjunction with phosphinate; their main advantage is related to the enhancement of compactness of the char layer formed. Diphosphonium clay is instead effective in further improving the fire behaviour of the foams because of the flame retardancy action of phosphonium: both PHRR and THE were decreased. The analysis of cone calorimeter data showed that clays act through physical effect constituting a barrier at the surface which is effective in preventing or slowing the diffusion of volatiles and oxygen, while phosphinate and phosphonium are more effective owing to their combined action in both condensed and gas phases. 相似文献
10.
The complexation of Al(III) with d-gluconic acid was studied in solution by means of pH-potentiometry, ESI mass spectrometry and one- and two-dimensional NMR spectroscopy. Six complexes were found to form in solution from pH 2 to 10: [AlL]2+, [AlLH−1]+, [AlLH−2], [AlLH−3]−, [AlL2H−1] and [AlL2H−2]−. NMR spectroscopy indicated very complicated chemical exchange processes between the free ligand and gluconic acid molecules bound in the metal complexes, with different coordination modes resulting in changes both of the chemical shift and of the line shape of the signals. A solid complex [AlL2H−1] · 2H2O was isolated as a microcrystalline powder and characterized. The structures of the complexes are discussed on the basis of the spectroscopic results and MM force field calculations. 相似文献