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991.
D. Valerini A. P. Caricato M. Lomascolo F. Romano A. Taurino T. Tunno M. Martino 《Applied Physics A: Materials Science & Processing》2008,93(3):729-733
We report the use of PLD to grow different ZnO nanostructures. Very different film morphologies have been observed using different
laser wavelengths to ablate the target. The influence of substrate temperature and oxygen background pressure on the film
morphology has been investigated too. Smooth and rough films, hexagonal pyramids and columns have been obtained by using a
KrF excimer laser (248 nm) for the target ablation, while hexagonal hierarchical structures and pencils have been obtained
by using ArF (193 nm). Photoluminescence and X-ray diffraction measurements revealed the good quality of the samples, in particular
of those deposited using the ArF laser beam. 相似文献
992.
M. La Cognata C. Spitaleri S. Cherubini M. Gulino L. Lamia R. G. Pizzone S. M. R. Puglia G. G. Rapisarda S. Romano M. L. Sergi A. Tumino 《Few-Body Systems》2008,44(1-4):353-356
The t(p,p)t and t(p,d)d channels have been investigated in an indirect way through the 2H(t,tp)n and 2H(t,dd)n three-body reactions performed at E t = 35.5?MeV in quasi-free kinematics. The agreement with direct data supports the pole approximation at energies above the Coulomb barrier. 相似文献
993.
Brackley CA Ebenhöh O Grebogi C Kurths J de Moura A Romano MC Thiel M 《Chaos (Woodbury, N.Y.)》2010,20(4):045101
The methods of nonlinear systems form an extensive toolbox for the study of biology, and systems biology provides a rich source of motivation for the development of new mathematical techniques and the furthering of understanding of dynamical systems. This Focus Issue collects together a large variety of work which highlights the complementary nature of these two fields, showing what each has to offer the other. While a wide range of subjects is covered, the papers often have common themes such as "rhythms and oscillations," "networks and graph theory," and "switches and decision making." There is a particular emphasis on the links between experimental data and modeling and mathematical analysis. 相似文献
994.
Dino Habibović Aner Čerkić Mustafa Busuladžić Azra Gazibegović-Busuladžić Senad Odžak Elvedin Hasović Dejan B. Milošević 《Optical and Quantum Electronics》2018,50(5):214
Strong-field ionization of nonlinear planar triatomic molecules by a bicircular laser field is analyzed within the improved molecular strong-field approximation. Our calculations include additional interaction between the liberated electrons and atomic or ionic centers of the parent molecular ion. The used bicircular field consists of two counterrotating circularly polarized fields having angular frequencies \(r \omega\) and \(s \omega\), with integer r and s. In the case when the laser-field-polarization plane is parallel to the plane of the considered molecule (example of ozone molecule is analyzed), the corresponding photoelectron spectra are not rotationally symmetric. On the other hand, when these planes are mutually perpendicular, for the \((r\omega ,s\omega )=(\omega ,3\omega )\) bicircular field, the electron spectra satisfy the corresponding rotational symmetries. Analyzing the obtained spectra and the corresponding symmetries, one can extract information about molecular orientation and structure. This technique may also be useful for more complex polyatomic molecules. 相似文献
995.
H.J. Quevedo G. Zhang A. Bonasera M. Donovan G. Dyer E. Gaul G.L. Guardo M. Gulino M. La Cognata D. Lattuada S. Palmerini R.G. Pizzone S. Romano H. Smith O. Trippella A. Anzalone C. Spitaleri T. Ditmire 《Physics letters. A》2018,382(2-3):94-98
We discuss experimentally and theoretically neutron production from the laser driven explosion of gas clusters prepared near the liquid-gas critical point. We let deuterated methane that was prepared very close to its critical temperature and pressure expand through a conical nozzle to create clusters, and then irradiated those clusters with a high intensity pulse from the Texas Petawatt Laser. After ionization, the clusters explode producing energetic ions, some of which fuse with resultant neutron emission. We show that the critical fluctuations present in the nozzle before the expansion influence the dynamics of neutron production. Neutron production near the critical point follows a power law, which is a signature of a second order phase transition and it is consistent with the Fisher model. This result might be relevant for energy production from fusion reactions. 相似文献
996.
Feasibility of low-energy radiative-capture experiments at the LUNA underground accelerator facility
D. Bemmerer F. Confortola A. Lemut R. Bonetti C. Broggini P. Corvisiero H. Costantini J. Cruz A. Formicola Zs. Fülöp G. Gervino A. Guglielmetti C. Gustavino Gy. Gyürky G. Imbriani A. P. Jesus M. Junker B. Limata R. Menegazzo P. Prati V. Roca D. Rogalla C. Rolfs M. Romano C. Rossi Alvarez F. Schümann E. Somorjai O. Straniero F. Strieder F. Terrasi H. P. Trautvetter A. Vomiero 《The European Physical Journal A - Hadrons and Nuclei》2005,24(2):313-319
The LUNA (Laboratory Underground for Nuclear Astrophysics) facility has been designed to study nuclear reactions of astrophysical interest. It is located deep underground in the Gran Sasso National Laboratory, Italy. Two electrostatic accelerators, with 50 and 400 kV maximum voltage, in combination with solid and gas target setups allowed to measure the total cross-sections of the radiative-capture reactions ^2H2H(p, )^3He3Heand ^14N14N(p, )^15O15Owithin their relevant Gamow peaks. We report on the gamma background in the Gran Sasso laboratory measured by germanium and bismuth germanate detectors, with and without an incident proton beam. A method to localize the sources of beam-induced background using the Doppler shift of emitted gamma rays is presented. The feasibility of radiative-capture studies at energies of astrophysical interest is discussed for several experimental scenarios. 相似文献
997.
Image velocimetry techniques, which extract motion information by comparison of image regions, typically make use of cross-correlation to measure the degree of matching. In this work, a novel measure of the dissimilarity between interrogation windows is proposed which is based on a more robust estimator than cross-correlation. The method is validated on synthetic images and on two experimental data sets obtained from a periodically pulsed jet and a backward-facing step. The former is a basically laminar flow, whereas the latter is fully turbulent. Both of them are characterized by regions of high velocity gradients. The efficiency of the robust image velocimetry (RIV) is compared with a cross-correlation algorithm (PIV). The analysis of results shows that the RIV is less sensitive to the appearance and disappearance of particles, and to high velocity gradients and, in general, to noise, generating less spurious velocity vectors. As a consequence RIV resolves better the vorticity peaks at the center of the vortex rings generated by the pulsed jet, obtaining, for a given interrogation window size, a higher spatial resolution. Moreover, in the analysis of the flow field generated by the backward-facing step, the RIV performs better in the shear layer at the border of the recirculation region, leading to a more reliable estimation of Reynolds shear stress and horizontal velocity component. 相似文献
998.
The aziridine prepared from the 2-pyridineimine derived from (S)-valinol underwent ring-opening by attack of nitrogen, sulfur, and oxygen nucleophiles. Complete or prevalent regioselectivity was obtained using cerium trichloride heptahydrate as a catalyst. In some cases, the N-substituent could be removed by an oxidative protocol. 相似文献
999.
Paravidino M Scheffelaar R Schmitz RF Kanter FJ Groen MB Ruijter E Orru RV 《The Journal of organic chemistry》2007,72(26):10239-10242
Highly functionalized and conformationally constrained depsipeptides based on a dihydropyridin-2-one core are prepared by the combination of a four- and a three-component reaction. The synthesis combines a one-pot Horner-Wadsworth-Emmons/cyclocondensation sequence leading to isonitrile-functionalized DHP-2-ones with an isonitrile-based Passerini multicomponent reaction (MCR). Substituents could be independently varied at six different positions. The two MCRs could also be performed as a one-pot procedure, simplifying the protocol and leading to a new and highly variable six-component process. 相似文献
1000.
A norbornene-mediated palladium-catalyzed sequence is described in which two alkyl-aryl bonds and one alkenyl-aryl bond are formed in one pot with use of microwave irradiation. A variety of symmetrical and unsymmetrical oxygen-, nitrogen-, silicon-, and sulfur-containing tricyclic heterocycles were synthesized from a Heck acceptor and an aryl iodide containing two tethered alkyl halides. This approach was further applied to the synthesis of a tricyclic mescaline analogue. 相似文献