The lithiation of 5,5′‐dibromo‐2,2′‐bithiophene with one equivalent of an alkyllithium such as n‐BuLi or s‐BuLi was studied by varying the residence time in flow microreactors. With a short residence time, the product 2,2′‐bithiophene (3) derived from dilithiation was obtained preferentially and a significant amount of the starting material 5,5′‐dibromo‐2,2′‐bithiophene remained unchanged. An increase in the residence time caused a higher yield of the product 5‐bromo‐2,2′‐bithiophene derived from monolithiation with expense in the yields of 2,2′‐bithiophene and 5,5′‐dibromo‐2,2′‐bithiophene. The lithiation using MeLi gave the product 5‐bromo‐2,2′‐bithiophene preferentially even with a very short residence time. 相似文献
We investigated how pretreatment and high-LET beam irradiation affected the ion-track dissolution rate in poly(vinylidene fluoride) (PVDF) films by SEM observations and conductometric analysis in order to develop the preparation methodology of nano-sized ion-track membranes. PVDF thin films irradiated with four types of ion beams were exposed to a 9 mol/dm3 KOH aqueous solution after their storage in air at 120 °C. This heating treatment was found to enhance the etch rate in the latent track, both in the inner core and outer halo regions, without changing that in the bulk, probably due to the formation of parasitic oxidation products facilitating the introduction of the etching agent to improve the etchability. Additionally, the irradiation of heavier higher-LET ions, causing each track to more activated sites (like radicals), was preferable for achieving effective etching. 相似文献
We examine optically induced birefringence in semicrystalline azopolymer films that are held at glass-transition temperature Tg. The birefringence increases markedly after interception of the pump beam; the saturation value depends on exposure time. In addition, the induced birefringence is completely erased by irradiation with a circularly polarized beam at Tg. Using this thermally assisted method, we demonstrate the holographic recording of a test image. The intensity of the diffracted beam also increases after interception of the writing beams. Furthermore, the retrieved image is found to have a resolution of approximately 30 lp/mm. This resolution is comparable with that of the optical setup that is used. Accordingly, the thermally assisted recording by use of semicrystalline azopolymers is a promising method for reversible holographic storage. 相似文献
This paper proposes a method for solving stochastic job-shop scheduling problems based on a genetic algorithm. The genetic algorithm was expanded for stochastic programming. In this expansion, the fitness function is regarded as representing fluctuations that may occur under stochastic circumstances specified by the distribution functions of stochastic variables. In this study, the Roulette strategy is adopted for selecting the optimum solution in terms of the expected value. Within this algorithm, it is expected that the individual that appears most frequently must give the optimum solution. The effectiveness of this approach is confimed by applying it to stochastic job-shop scheduling problems. I compare the approximately optimum solutions found by this approach with the truly or approximately optimum solutions obtained by other conventional methods, and discuss the performance and effectiveness of this approach. 相似文献
It has been proposed that vapor-mist dielectrics in which mixing liquid droplets such as tetrachloroethlene in a gas have the ability of increasing flashover, impulse voltage, and of suppressing partial discharge. Vapor-mist methods have been performed on other materials and the effect of the mist can also be obtained on benzene, hexane, and even water as general materials. Although these studies have been carried out, neither the discharge mechanism on vapor-mist nor the reason for the increase of the discharge voltage is understood fully because the mist is of various sizes. On the other hand, agglomeration of water molecules can be studied with the FR-IR method, and are classified into monomer, dimer, trimer (including polymer). Water gives mist stats which are significant in discussing effects. This paper describes states of water mist and their effect under nonuniform field with positive and negative polarities. Water mist in vapor exists as dimer and trimer, and their amount decreases with the reduction of temperature. These mists have no effect on discharge suppression. However, when the mists are formed by space charges, the inception voltage is increased by these mists in the negative polarity. 相似文献
3-Fluorobenzoic acid adsorbed on Au(1 1 1), Au(1 0 0) and Au(1 1 0) electrodes has been investigated using in situ IR reflection spectroscopy, UV-visible reflectivity measurements, and differential capacity measurements. As determined by IR reflection spectroscopy, the vertically adsorbed 3-fluorobenzoate is the predominant species at positive potentials, and the flat-lying type is adsorbed at negative potentials. In the UV-visible reflectivity measurements, the reflectivity changes for the vertically adsorbed and flat-lying 3-fluorobenzoates on the Au(1 0 0) electrode were observed at different frequency regions. No UV-visible reflectivity signal was observed for the Au(1 1 0) electrode, and it was proved that the UV-visible reflectivity change has a strong single crystal surface dependence. For the vertical configuration, a large contribution between the 5d orbital of Au and the 2p orbital of oxygen in 3-fluorobenzoate was found for the cluster model by DFT calculation. 相似文献
The iron(III) chloride‐catalyzed Friedel–Crafts arylation of 4‐aryl‐4‐methoxy‐2,5‐cyclohexadienones, which were easily prepared by the phenyliodine(III) diacetate (PIDA)‐mediated oxidation of 4‐arylphenols in methanol, proceeded site‐selectively to form meta‐terphenyl (2,4‐diarylphenol) derivatives in good yields. The subsequent PIDA‐mediated oxidation and iron(III) chloride‐catalyzed Friedel–Crafts arylation of the resulting products gave the corresponding 2,4,6‐triarylphenol derivatives. The present method provides useful highly substituted polyarylated compounds.
3-Pyridinecarboxylic acid (3-PC) adsorbed on low index face electrodes in NaF solution were investigated using in situ Fourier transform-infrared (FTIR) spectroscopy and differential capacity measurements. Two types of vertically adsorbed 3-PC were confirmed on the electrodes, while flat-lying adsorbed species were not observed at the potentials measured. At negative potentials, 3-PC molecules adsorb vertically on the electrode via the lone pair electrons of the pyridine ring nitrogen atom, and at positive potentials, 3-PC adsorbs vertically via the two oxygen atoms of the carboxyl group. 相似文献
The purpose of this study was to develop a system for communication between a human and a computer generated (CG) character
to make him or her more peaceful and cheerful. Nonverbal communication using such things as facial expression, a nod, or a
hand gesture is very important for reciprocal communication between humans. In this study, an image registered by infrared
rays which describes the thermal distribution of the face and neck has been used to develop a system for communication between
a human and a CG character. The CG character can synchronize its nod with a person’s nod by predicting his or her nod angle.
The measured feature parameter is input to a fuzzy algorithm system to obtain the nod angle of a person in front of an infrared
camera, and then a moving-average model is used to predict the nod angle of the person. The average error of the nod angle
obtained by the system has been estimated as about 5°. The CG character nods its head, not only when the human nods his or
her head, but also when the human shakes his or her head to the left or right. 相似文献