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31.
Esa Toukoniitty Päivi Mäki-Arvela Ahmad Kalantar Neyestanaki Ensio Laine Jyri-Pekka Mikkola Tapio Salmi Dmitry Yu. Murzin 《Reaction Kinetics and Catalysis Letters》2001,73(1):3-11
In the presence of ultrasound both the initial hydrogenation rate of 1-phenyl-1,2- propanedione and the enantiomeric excess of the main product, i.e. (R)-1-hydroxy- 1-phenylpropanone, increased by 75 % and 52 % in toluene, respectively, as compared to the silent hydrogenation. 相似文献
32.
We introduce the concept of average homogeneity of a measure by comparing the measure to the uniform distribution in a relatively simple way. This leads to a very general notion which may be regarded as an inverse of porosity. In this paper the emphasis is given to relations between homogeneity and dimensions of measures. First we consider the effect of homogeneity on dimensions by proving an upper bound to the Hausdorff dimension as a function of homogeneity and its order. The opposite question of how dimensions effect homogeneity is solved by giving an upper bound to homogeneity in terms of upper packing dimension. We also illustrate by examples that all our results are the best possible ones.Mathematics Subject Classification (2000): 28A75, 28A80MJ acknowledges the support of the Academy of Finland, project #48557. 相似文献
33.
Mohd Khairul Hisham Ismail Mazlina Esa Mohd Fairus Mohd Yusoff Noor Asniza Murad 《电子科技学刊:英文版》2016,14(3):242-248
In recent years, the potential of renewable green energy sources has been extensively studied. The proven technology which is photovoltaic solar cells strictly depends on daylight and produces low-efficiently. To overcome the restrictions, one technology studied is through harvesting the thermal radiation energy which can provide a 24-hour energy source. The continuity of energy sources promises very good energy conversion especially for military applications. This article presents a new structure that can harvest the abundant thermal radiation energy into usable energy at the wavelength of 10 m. A rectangular structure with a perturbation slit was designed to integrate with a rectifier circuit for green energy conversion. The slit tunnel junction guided the electromagnetic field into a junction where the energy could be collected and converted. An enhancement factor of approximately 110.6 can be achieved by a perturbation slit length of 1.0 m. The results extracted from the proposed design promise a better candidate to overcome the disadvantages of photovoltaic solar cells for energy harvesting devices. 相似文献
34.
Esa Haapaniemi 《Magnetic resonance in chemistry : MRC》2017,55(9):804-812
The 1H, 13C{1H}, and 31P NMR spectral parameters of some pyrophosphates were determined in CDCl3. The most complicated 1H spectrum can be solved fully only as (A3MN)R6XX′R6′(MNA3)′, where R6 (= ―N(CH3)2) is coupled only to phosphorus (X). Second‐order coupling between phosphorus was found and solved with iterative analysis. A signal shape of one of the carbon resonance cannot be explained only with couplings. Explanation for exceptional shape was searched from molecular modeling results. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
35.
Juha Merta Per Stenius Esa Pirttinen 《Journal of Dispersion Science and Technology》2013,34(1-2):677-697
This paper reports on studies of the rheological properties of cationic starch (CS)/ surfactant systems. The degree of substitution of the CS was 0.1 - 0.8. Surfactants investigated were sodium dodecyl sulfate (SDS), potassium octanoate (KOct), sodium decanoate (NaDe)potassium dodecanoate (KDod), sodium oleate (NaOl) and sodium erucate (NaEr). Aggregation of surfactant micelles with the polymer produces a hydrophobic and pseudoplastic gel-like complex phase with low water content and high viscosity. The rheological behavior of the gels is described by the Herschel-Bulkley model. In dilute aqueous solution the CS/surfactant aggregate structure resembles a randomly coiled polymer network, in which polymer molecules are linked by micelles. The rheological data for the gel are compatible with the assumption that the surfactants form liquid crystalline structures with the polymer anchored to the surfactant aggregates, as recently suggested for analogous systems. However, this conjecture needs to be corroborated by more direct determinations of the structure. 相似文献
36.
Joshua A. Carroll Emad L. Izake Biju Cletus Esa Jaatinen 《Journal of Raman spectroscopy : JRS》2015,46(3):333-338
Increasing worldwide terrorist attacks involving explosives presents a growing need for a rapid and ranged explosive detection method that can safely be deployed in the field. Stand‐off Raman spectroscopy shows great promise; however, the radiant exposures of lasers required for adequate signal generation are often much greater than what is safe for the eye or the skin, restricting use of the technique to unpopulated areas. Here, by determining the safe exposure levels for lasers typically used in Raman spectroscopy, optimal parameter values are identified, which produce the largest possible detection range using power densities that do not exceed the eye‐safe limit. It is shown that safe ultraviolet pulse energies can be more than three orders of magnitude greater than equivalent safe visible pulse energies. Coupling this to the 16‐fold increase in Raman signal obtained in the ultraviolet at 266 nm over that at 532 nm results in a 131 times larger detection range for the eye‐safe 266‐nm system over an equivalent eye‐safe 532‐nm laser system. For the Raman system described here, this translates to a maximum range of 42 m for detecting Teflon with a 266‐nm laser emitting a 100‐mm diameter beam of 23.5‐mJ nanosecond pulses. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
37.
A study of 1-hexene polymerization with ethylene-bis(9-fluorenyl) hafnium dichloride has been carried out using two different cocatalyst systems, methyl-aluminoxane/trimethylaluminum (MAO/TMA) and tris-isobutyl-aluminum/N,N-dimethylanilinium tetrakis(pentafluorophenyl) borate (TIBA/borate). When MAO/TMA was used, 1-hexene polymerized into a low molar mass poly(1-hexene) with low catalytic activity. Activation with TIBA/borate increased polymerization activity drastically as well as the molar mass of the polymers. In order to analyze differences in the activity profiles, UV-Vis spectroscopy was employed to investigate ligand to metal charge transitions (LMCT) of the hafnocene dichloride during the activation process. The low catalytic activity and the fast chain transfer to the cocatalyst with MAO/TMA may originate from strong bonding between the metallocene cation and the MAO/TMA species thus obstructing monomer coordination and insertion. 相似文献
38.
Esa Nummelin 《Probability Theory and Related Fields》1990,86(3):387-401
Summary Let (S
n
) be a sequence ofR
d
-valued random variables adapted to the internal history of a stationary sequence of random elements (X
n
). We formulate conditions under which the principle of large deviations holds true for the sequence (S
n
). 相似文献
39.
Umar Suleiman Dauda NikNoordini NikAbdMalik Mazlina Esa Kamaludin Mohd Yusof Mohd Fairus Mohd Yusoff Mohamed Rijal Hamid 《电子科技学刊:英文版》2016,14(2):111-117
Signals arrive out of phase at the intended receiver from collaborative beamforming (CB) nodes due to the instability in the output frequency signals of the universal software radio peripheral's (USRP) local oscillator (LO). These nodes including the target must synchronize their oscillator frequencies for coherent signal reception. In order to do this, frequencies and phases of the signals should be estimated in software defined radio (SDR) and smoothen with nonlinear filters such as the extended Kalman filter (EKF). The process noise parameters of the NI USRP-2920 nodes will have to be calculated and used with the EKF process noise covariance matrix. These nodes are green communication hardware devices where most of the hardware units are now software defined. This article uses the direct spectrum method to obtain the phase noise values at various frequency offsets of the NI USRP-2920 in order to calculate the power spectral density of fractional frequency fluctuation. By applying the power-law noise model to this obtained value, the generated white frequency noise and random walk frequency noise values are q1=1.9310-21 and q2=5.8610-18, respectively. 相似文献
40.
The first synthetic route to amaminol A with use of an organocatalytic intramolecular Diels-Alder reaction is reported. The absolute stereochemistry is proven with a crystallographic image of a cyclic carbamate of amaminol A. 相似文献