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The perception of smell is dominated by an hedonic dimension, with changes in left and right orbitofrontal activation evident in responses to odours of different valence. Electrophysiological (EEG) recordings were used to investig...
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The perception of smell is dominated by an hedonic dimension, with changes in left and right orbitofrontal activation evident in responses to odours of different valence. Electrophysiological (EEG) recordings were used to investigate differences in hemispheric activation associated with different hedonic responses to a low concentration of a single compound (damascenone: fruity, berry smell). Stimulus delivery (air, or air with odour) was synchronised with inspiration using a continuous respiration olfactometer. EEG responses were analysed using traditional power spectrum techniques to determine the relationship of the brain activity to the reported odour liking responses. Differences in response to the odour were evident in comparison with air, and also between response groups. Using the same odour to evoke different hedonic responses, power spectrum analysis revealed a non-significant trend for left frontal differences in EEG associated with different liking responses to damascenone. This demonstrated quantification of the neurophysiological effects associated with odour liking.
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Samariurn cobalt films were prepared on silicon substrates with and without a chromium buffer layer at room temperature and 600degreesC using direct current unbalanced magnetron sputtering. For obtaining ideal magnetic properties,...
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Samariurn cobalt films were prepared on silicon substrates with and without a chromium buffer layer at room temperature and 600degreesC using direct current unbalanced magnetron sputtering. For obtaining ideal magnetic properties, the films should be free from impurities, such as O, Al and others. Rutherford backscattering spectrometry and heavy ion elastic recoil detection analysis were used to determine the composition and film thickness and to monitor the light element contamination across film thickness. X-ray diffractometer and superconducting quantum interference device were employed to characterize the structure and magnetic properties of the films, respectively. The results obtained led to an improved design of the ground shield and the use of a sorption pump to effectively minimize aluminium and oxygen concentration in the films, respectively. (C) 2004 Elsevier Ltd. All rights reserved.
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The focus of the Letter is to discuss ways of overcoming hitherto fundamental limitations imposed by nature on our ability to study structures by diffraction. TCD, which is based on diffraction of particles in groups correlated in...
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The focus of the Letter is to discuss ways of overcoming hitherto fundamental limitations imposed by nature on our ability to study structures by diffraction. TCD, which is based on diffraction of particles in groups correlated in time and space, could be the answer to some of the problems. The physics of TCD is discussed, which is fundamentally different to all diffraction methods presently used. Neutrons are the most appropriate particles to "benefit" from TCD. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 16]
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We report on a two-photon absorption-induced photoenhancement effect on a densely packed CdSe/ZnSe/ZnS core-shell semiconductor nanocrystal solid film. The enhancement is found to be irreversible without a noticeable blueshift in ...
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We report on a two-photon absorption-induced photoenhancement effect on a densely packed CdSe/ZnSe/ZnS core-shell semiconductor nanocrystal solid film. The enhancement is found to be irreversible without a noticeable blueshift in emission spectra, hence we attribute the enhancement to the photoannealing of interface defects rather than to the photo-oxidation or surface passivation by other molecules. The two-photon enhancement allows us to record the enhanced spots three dimensionally, hence demonstrating the feasibility of its application to multilayered optical data storage based on nanocrystal solids. (C) 2004 American Institute of Physics.
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This paper provides a photopolymerizing material suitable for stereolithography of complex submicrometer-sized three-dimensional (3D) structural elements to a broad scientific public. Here, we present the formulation of a polymer ...
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This paper provides a photopolymerizing material suitable for stereolithography of complex submicrometer-sized three-dimensional (3D) structural elements to a broad scientific public. Here, we present the formulation of a polymer (LN1 resin) that allows further research in the field of nanofabrication and -technology as it surpasses current material limitations. The polymer consists of multifunctional acrylate oligomers as binder, polyfunctional, monomers, and a photoinitiator (PI). The chemistry to form 3D structures is based on photopolymerization of the acrylate system initiated by free-radical species that are triggered by two-photon absorption of a PI. Important parameters of photocuring, such as the effects of PI concentration, temperature, and light intensity, were studied using photocalorimetry. The thermal stability of the material was tested using thermal gravimetric analysis, providing key information for electronic and photonic applications. Photonic-crystal structures generated from this resin exhibiting photonic stop gaps in near-infrared- and telecommunication-wavelength regions are presented.
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We reported in this paper the use of annular beam illumination to control the transverse and vertical sizes of two-dimensional dot array structures fabricated with two-photon photopolymerization Dot arrays with an element diameter...
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We reported in this paper the use of annular beam illumination to control the transverse and vertical sizes of two-dimensional dot array structures fabricated with two-photon photopolymerization Dot arrays with an element diameter of less than 300 nm, a lattice spacing less than 1 mum has been produced. At the same time, the structure height exhibits a 1.94 times increase averagely and the height/width aspect ratio is improved from 1.21, for the circular beam,illumination case, to,236 after using annular beam illumination.
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We report on the experimental investigation carried out in the polarisation characteristics of femtosecond pulsed and continuous wave beams propagating through a 1 x 2 fibre coupler. It is demonstrated that the polarisation states...
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We report on the experimental investigation carried out in the polarisation characteristics of femtosecond pulsed and continuous wave beams propagating through a 1 x 2 fibre coupler. It is demonstrated that the polarisation states of pulsed and continuous wave illumination over the broad wavelength range can be preserved in a conventional fused fibre coupler. Furthermore, the fibre coupler acts as a low-pass spectral filter in the visible wavelength range with a splitting ratio between 99.6/0.4 and 99.7/0.3. The result is of importance for fibre-optic second harmonic generation microscopy which requires the polarisation preservation to extract molecular organization of a sample. (c) 2004 Elsevier Ltd. All rights reserved.
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The standard Genetic Algorithm, originally inspired by natural evolution, has displayed its effectiveness in solving a wide variety of complex problems. This paper describes the use of the natural phenomenon known as the Baldwin e...
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The standard Genetic Algorithm, originally inspired by natural evolution, has displayed its effectiveness in solving a wide variety of complex problems. This paper describes the use of the natural phenomenon known as the Baldwin effect (or cross-generational learning) as an enhancement to the standard Genetic Algorithm. This is implemented by using an artificial neural network to store aspects of the population's history. It also describes a method by which the negative side effects of a large elite sub-population can be counter-balanced by using an ageing coefficient in the fitness calculation. [References: 19]
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The applicability of solid phase microextraction (SPME) as a technique for the concentration of cheese aroma for analysis by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) was assessed in t...
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The applicability of solid phase microextraction (SPME) as a technique for the concentration of cheese aroma for analysis by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) was assessed in this preliminary study. Three each of the following cheese varieties were examined: cheddar, hard grating and mold-ripened blue. Volatile components were concentrated by Carboxen-PDMS SPME fibres for 16 h (overnight) and analysed by GC-MS and GC-O. Odor compounds, which could be perceived at the olfactory port (OP), were matched with electron impact (EI) and methanol chemical ionization (CI) mass spectra. The volatile compounds identified were compared to previously reported cheese aroma compounds. Of the components identified via olfactometry, methanethiol, methional, dimethyl trisulfide and butanoic acid were present in all of the cheeses implying their essential role in the formation of basic cheese aroma. A number of alkyl-pyrazines were also found to impart roasted nutty, raw potato and savoury broth-like notes in some of the cheeses. In all cases, the aroma active compounds identified via olfactometry were in agreement with those reported in the literature. In a separate study, it,was demonstrated on a number of cheeses that the adsorption of most important aroma volatiles increased consistently up to 16h; i.e. sulfur compounds, lactones, pyrazines, phenolic compounds and benzene derivatives. For the strong-smelling pecorino and blue cheeses, however, some analyte displacement effects were observed. Data indicated that a sampling time between 9 and 16 h was appropriate and displacement/competition reactions tended to occur in strong cheeses, i.e. those which have undergone extensive lipolysis e.g. pecorino, very high concentration of butanoic and hexanoic acid, and/or beta-oxidation e.g. blue cheese, with high concentrations of 2-heptanone and 2-nonanone.
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