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排序方式: 共有120条查询结果,搜索用时 156 毫秒
101.
Paweł Brzuzan Łukasz Jurczyk Maciej Woźny Maciej Góra Michał K. Łuczyński Henryk Kuźmiński 《Polycyclic Aromatic Compounds》2013,33(5):345-365
Cyclopenta[c]phenanthrene (CP[c]Ph) is a PAH member that shows similarities to bay-and fjord region possessing PAHs. On the basis of X-ray measurements it was found that the molecule of this hydrocarbon is planar. In this case, intramolecular strains caused by repulsion between protons in the pseudo fjord-region are balanced by both the shortening of some bonds which acquire more double bond character, and by the enlargement of exocyclic angles within the pseudo fjord-region. The activity of CP[c]Ph was investigated in vivo in rainbow trout, Oncorhynchus mykiss. The CYP1A mRNA levels following 48h-treatment with CP[c]Ph or benzo[a]pyrene (B[a]P; positive control) were determined and compared with incidences of clastogenic changes observed in the peripheral blood erythrocytes. We have found that the ability to induce CYP1A by these PAH compounds is positively correlated with the incidences of clastogenic changes in rainbow trout erythrocytes. 相似文献
102.
Microstructures, electrochemical properties of Ti–Ni and ternary Ti–Ni–Mg alloy were studied after they had been submitted to high-energy ball milling. Influence of milling time and Mg addition on the microstructures of the mechanically milled Ti–Ni alloys was investigated by XRD, SEM. Cycling performances of the electrodes prepared by the milled powders were measured under galvanostatic conditions. It is found that the binary Ti–Ni alloy undergoes a refinement, dynamical recrystallization and amorphization process. With doping of Mg to the starting Ti–Ni powders, an FCC Ti–Mg structure was detected along with the main TiNi BCC phase. First principle calculation was applied to compare the thermodynamic stabilities of several binary alloys involving Ti, Ni and Mg. It was decided that the final product of milling Mg doped Ti–Ni contains an FCC structured TiMg3 phase, which damages electrochemical performance in general as a result of coating effect on the TiNi phase. 相似文献
103.
Mieczyslaw M. Boduszynski 《Petroleum Science and Technology》2013,31(3):211-232
ABSTRACT This paper provides a critical analysis of the average molecular structure determination For high boiling and nondistll-lahle fractions in fossil fuels. The emphasis is on molecular weight distribution and compound-class composition. The wide molecular weight distribution, resulting from the different volatility of the various chemical classes of compounds comprising these complex mixtures, is demonstrated to be the major limitation. 相似文献
104.
105.
Dorota Derewiaka Mieczyslaw Obiedziski 《European Journal of Lipid Science and Technology》2010,112(10):1130-1137
The aim of this study was to evaluate the effect of heat treatment of selected animal products on formation of cholesterol oxidation products (COP) and also to determine their content in selected pates and fermented pork sausage which are available on the Polish market. COP content in pates was significantly lower as compared to fermented sausages, and ranged from 39.5 to 43.1 µg/100 g; COP in sausages ranged from 195.8 to 263.4 µg/100 g of product. COP content in pan fried meats, chops, and fish fillets varied from 6.2 to 991.2 µg/100 g products. This paper demonstrates the method for determining the content of COP by the use of selected ion technique with the aid of MS. Practical applications: The method described is useful for the investigation of oxysterols in food matrices. The method is used for the investigation of the presence and content of COP, such as: 7β‐hydroxycholesterol, 5α,6α‐epoxycholesterol, 5β,6β‐epoxycholesterol, 5α‐cholestane‐3β,5β,6β‐triol, 7‐ketocholesterol, and 25‐hydroxycholesterol. The obtained data about COP content in selected animal products and their formation during heat treatment are crucial for creating a reliable database to assess their daily intakes and biological effects in humans. 相似文献
106.
107.
This paper presents the experiences from the practical implementation and the results of the experimental validation of the balance-based adaptive control (B-BAC) methodology in the application to two local control problems in the simple heat distribution system: the control of the outlet temperature for the electric flow heater and the control of a fluid flow process through the equal percentage valve. Evaluation criteria include measure of the control variable performance as well as the manipulated variable action. The results illustrate both the possibility of the practical implementation of the B-BAC methodology and the fact that in some cases this methodology ensures better disturbance rejection with the tracking properties comparable to the conventional PI controller. 相似文献
108.
Mieczyslaw Lapkowski Jerzy Zak Krzysztof Karon Bogdan Marciniec Wieslaw Prukala 《Electrochimica acta》2011,(11):4105
We report on electronic and spectroscopic properties of a new synthesized bicarbazole monomer and its electroactive polymer. In the monomer a branching of the carbazole conjugation occurs through N-linked, conjugated bridge between two carbazole units. That extended conjugation path adds rigidity to the large molecule, which leads in electropolymerization to the formation of ordered polymeric structure. That result is supported by an evident hypsochromic shift in both the absorption and fluorescence spectra measured for the monomer and its polymer. The effect of broadening of the band gap of the created polymer demonstrates a new route in designing of monomers that may lead to stable polymeric materials emitting blue light. The ex situ IR spectra of the polymer and the course of the electropolymerization monitored using in situ IR measurements confirm the assumed structure of the obtained polymer. Electrochemical, UVVis-, and EPR-spectroelectrochemical data have been provided to discuss the properties of the system and to support the proposed reaction mechanism. 相似文献
109.
L.W. Huang O. Elkedim M. Nowak M. Jurczyk R. Chassagnon D.W. Meng 《International Journal of Hydrogen Energy》2012
Mg2−xAlxNi (x = 0, 0.25) electrode alloys with and without multiwalled carbon nanotubes (MWCNTs) have been prepared by mechanical alloying (MA) under argon atmosphere at room temperature using a planetary high-energy ball mill. The microstructures of synthesized alloys are characterized by XRD, SEM and TEM. XRD analysis results indicate that Al substitution results in the formation of AlNi-type solid solution that can interstitially dissolve hydrogen atoms. In contrast, the addition of MWCNTs hardly affects the XRD patterns. SEM observations show that after co-milling with 5 wt. % MWCNTs, the particle sizes of both Mg2Ni and Mg1.75Al0.25Ni milled alloys are decreased explicitly. The TEM images reveal that ball milling is a good method to cut long MWCNTs into short ones. These MWCNTs aggregate along the boundaries and surfaces of milled alloy particles and play a role of lubricant to weaken the adhesion of alloy particles. The majority of MWCNTs retain their tubular structure after ball milling except a few MWCNTs whose tubular structure is destroyed. Electrochemical measurements indicate that all milled alloys have excellent activation properties. The Mg1.75Al0.25Ni-MWCNTs composite shows the highest discharge capacity due to the synergistic effects of MWCNTs and Al on the electrochemical hydrogen storage properties of Mg2Ni-type alloy. However, the improvement on the electrode cycle stability by adding MWCNTs is unsatisfactory. 相似文献
110.
Flak D Braun A Michalow KA Wyrwa J Parlinska-Wojtan M Graule T Rekas M 《Journal of nanoscience and nanotechnology》2012,12(8):6401-6411
Nanoscaled Fe2O3 powders as candidates for gas sensing material for hydrogen detection were synthesized by the high temperature flame spray assisted combustion of ferrocene dissolved in benzene. X-ray diffraction (XRD) and selected area electron diffraction (SAED) show that the as prepared nanopowder consists of maghemite (gamma-Fe2O3) with low crystallinity. Thermal post-treatment causes a phase transformation towards hematite (alpha-Fe2O3) accompanied by an increase in the crystallinity. Upon exposure to air and hydrogen at elevated temperatures, both phases show a significant variation of conductivity and activation energy-as evidenced by impedance spectra-and thus a favorable sensor response, surpassing even that of flame-synthesized nanocrystalline tin dioxide. The conductivity has been identified as of electronic origin, affected by trap states located in the region adjacent to grain boundaries. Quantitative analysis of the impedance spectra with equivalent circuits shows that the conductivity is thermally activated and affected by the interaction of hydrogen with the sensor material. The calculated Debye screening length of gamma-Fe2O3 and alpha-Fe2O3 is about 27 nm and 16 nm, respectively, what contributes significantly to the sensitivity of the material. Gamma-Fe2O3 and alpha-Fe2O3 exhibit high sensor response towards hydrogen in a wide concentration range. Gamma-Fe2O3 shows n-type semiconducting behavior up to 573 K. Alpha-Fe2O3 shows p-type semiconducting behavior, as reflected in the dynamic changes of the resistivity. For both sensor materials, 523 K was the optimal operating temperature. 相似文献