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21.
Godofredo Bautista Giovanni Tapang Vincent Ricardo Daria 《Optics Communications》2009,282(18):3746-25899
We report parallel two-photon photopolymerization of microgear patterns by exposing a photoresist to holographically generated optical vortices. The optical vortices are created by imparting a helical pitch onto the incident light using a programmable lithographic phase mask realized with a computer addressable phase-only spatial light modulator. By varying the phase levels of the spatial light modulator, the truncated helical phase of an optical vortex results in output intensity patterns that typifies that of microgears instead of perfect doughnut beams. Our experiments and simulations are in good agreement implying a more efficient and highly parallel two-photon photopolymerization scheme that can be subsequently used for non-scanning fabrication of microgears. 相似文献
22.
J. L. Jiménez Pérez E. Rangel Vargas R. Gutiérrez Fuentes A. Cruz-Orea H. Bautista de León 《The European physical journal. Special topics》2008,153(1):511-513
In this paper we used thermal lens spectrometry to
determine the thermal diffusivity of cheese fats. We have used equal
concentrations of cheese fats from oaxaca, chihuahua, gouda, manchego and
mozzarella cheeses at 42°C temperature. The two lasers
mismatched mode experimental configuration was used with a He-Ne laser, as a
probe beam and an Ar+ laser as the excitation one. The characteristic
time constant of the transient thermal lens was obtained by fitting the
theoretical expression to the experimental data in order to obtain the
thermal diffusivity of the cheese fat samples. This measured thermal
property may contribute to a better understanding of the cheese fats
quality, which is very important in food industry. 相似文献
23.
Muñoz de la Peña A Mahedero MC Espinosa-Mansilla A Bautista Sánchez A Reta M 《Talanta》1999,48(1):15-21
The spectral characteristics of the inclusion of 1-naphthalenacetamide in beta-cyclodextrin have been studied by luminescence methods. The addition of bromoalcohols or bromoalkanes produces a decrease of the fluorescence of the inclusion complex, giving rise to a new band corresponding to phosphorescence emission. The emission intensity is much higher in the presence of bromoalkanes than in the presence of bromoalcohols. The deoxygenation of the solutions is achieved by flowing nitrogen, by the addition of sodium sulphite and by a combination of both methods, which results in the most effective approach. The phosphorescence emission is produced in the turbid suspension formed in the presence of the bromoalkane. The formation of microcrystals seems necessary to obtain phosphorescence emission from the ternary system. 相似文献
24.
25.
José Vicente Prof. Dr. José‐Antonio Abad Dr. María‐José López‐Sáez Dr. Peter G. Jones Prof. Dr. Delia Bautista Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(2):661-676
Complexes [Pd(C6H3XH‐2‐R′‐5)Y(N^N)] (X=O, NH; Y=Br, I; R′=H, NO2; N^N=N,N,N′,N′‐tetramethylethylenediamine (tmeda), 2,2′‐bipyridine (bpy), 4,4′‐di‐tert‐butyl‐2,2′‐bipyridine (dtbbpy)) react with RN?C?E (E=NR, S) or RC≡N (R=alkyl, aryl, NR′′2) and TlOTf (OTf=CF3SO3) to give, respectively, 1) products of the insertion of the C?E group into the C? Pd bond, protonation of the N atom, and coordination of X to Pd, [Pd{κ2‐X,E‐(XC6H3{EC(NHR)}‐2‐R′‐4)}(N^N)]OTf or [Pd(κ2‐X,N‐{ZC6H3(NH?CR)‐2‐R′‐4})(N^N)]OTf, or products of the coordination of carbodiimides and OH addition, [Pd{κ2‐C,N‐(C6H4{OC(NR)}NHR‐2)}(bpy)]OTf; or 2) products of the insertion of the C≡N group to Pd and N‐protonation, [Pd(κ2‐X,N‐{XC6H3(NH?CR)‐2‐R′‐4})(N^N)]OTf. 相似文献
26.
Time and space assembly line balancing considers realistic multi-objective versions of the classical assembly line balancing industrial problems. It involves the joint optimisation of conflicting criteria such as the cycle time, the number of stations, and/or the area of these stations. The different problems included in this area also inherit the precedence constraints and the cycle time limitations from assembly line balancing problems. The presence of these hard constraints and their multi-criteria nature make these problems very hard to solve. Multi-objective constructive metaheuristics (in particular, multi-objective ant colony optimisation) have demonstrated to be suitable approaches to solve time and space assembly line balancing problems. The aim of this contribution is to present a new mechanism to induce diversity in an existing multi-objective ant colony optimisation algorithm for the 1/3 variant of the time and space assembly line balancing problem. This variant is quite realistic in the automative industry as it involves the joint minimisation of the number and the area of the stations given a fixed cycle time limit. The performance of our proposal is validated considering ten real-like problem instances. Moreover, the diversity induction mechanism is also tested on a real-world instance from the Nissan plant in Barcelona (Spain). 相似文献
27.
28.
Making use of the general theory of connections invariant under a symmetry group which acts transitively on fibers, explicit solutions are derived for SU(2)×SU(2)-symmetric multi-instantons over S
2×S
2, with SU(2) structure group. These multi-instantons correspond to a principal fiber bundle characterized by a second Chern number given by 2m
2, with m an integer. 相似文献
29.
An efficient synthetic method for 3-aryl-5-dichloromethyl-2-isoxazolines has been established. Reactions between anhydrous chloral and acetophenones in hot acetic acid lead to 1-aryl-4,4,4-trichloro-3-hydroxybutan-1-ones (chloralacetophenones), which provided 1-aryl-4,4-dichlorobut-3-en-1-ones (2,2-dichlorovinylacetophenones) by dehydration and subsequent electrochemical reduction. These β,γ-unsaturated enones reacted with hydroxylamine yielding oxime intermediates whose treatment with aqueous sodium hydroxide gave novel 3-aryl-5-dichloromethyl-2-isoxazolines in fair to high yields. The molecular structure of a member of this family of compounds, 5-dichoromethy1-3-(4-methoxyphenyl)-2-isoxazoline, was determined by X-ray crystallography. 相似文献
30.