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21.
The problems related to our strong dependency on fossil fuels, i.e. greenhouse effect, energy dependency, urban pollution, are of growing importance in recent years. European Union (EU) Action plan of 2003, which had originated from Kyoto Agreement, defined a strategy for substitution of 20% of conventional fuel with the alternative one by 2020. Proved advantages of biodiesel usage in the system of public transport of passengers, with regard to exhaust gases emission above all, have been the decisive determinants for the actual promotion of biodiesel as ecologically “clean” fuel, while its wider usage gives important contribution to sustainable development of cities. This paper presents results of biodiesel-test run in Belgrade, as a part of the project BIO-PEX, which relates to the usage of this alternative fuel in real operating conditions in urban public transport system, with special emphasis on technical, ecological and operational aspects of biofuel usage. 相似文献
22.
Nalini P. Subramanian Xuguang LiVijayadurda Nallathambi Swaminatha P. KumaraguruHector Colon-Mercado Gang WuJong-Won Lee Branko N. Popov 《Journal of power sources》2009
Nitrogen-modified carbon-based catalysts for oxygen reduction were synthesized by modifying carbon black with nitrogen-containing organic precursors. The electrocatalytic properties of catalysts were studied as a function of surface pre-treatments, nitrogen and oxygen concentrations, and heat-treatment temperatures. On the optimum catalyst, the onset potential for oxygen reduction is approximately 0.76 V (NHE) and the amount of hydrogen peroxide produced at 0.5 V (NHE) is approximately 3% under our experimental conditions. The characterization studies indicated that pyridinic and graphitic (quaternary) nitrogens may act as active sites of catalysts for oxygen reduction reaction. In particular, pyridinic nitrogen, which possesses one lone pair of electrons in addition to the one electron donated to the conjugated π bond, facilitates the reductive oxygen adsorption. 相似文献
23.
Branko Deljanin Dusan Simic Alexander Zaitsev John Chapman Inga Dobrinets Annette Widemann Nicholas Del Re Tara Middleton Elena Deljanin Andrea De Stefano 《Diamond and Related Materials》2008,17(7-10):1169-1178
One of the commercial challenges today in the gem industry is to quickly identify the origin of color in pink diamonds — natural, treated and synthetic by use of standard and advanced gemological instruments.An analytical technique that is used by many gem labs involves UV fluorescence. The principle factors in the technique are the excitation wavelengths and the emission spectra. No systematic study of fluorescence of pink natural diamonds, pink treated and pink synthetic diamonds has been undertaken. This study is mainly focused on using fluorescence techniques to characterize pink diamonds and to compile a reference library of emission spectra. Longwave (LW) and shortwave (SW) fluorescence of 365, 254 and 220 nm illumination were used in a custom built microscope with a fluorescence camera to record images and a spectrometer to record spectral data with which to establish a correlation with the cause of color.Other advanced instruments (CL imaging, UV–VIS–NIR, FTIR, PL spectroscopy and electrical conductance) were used to establish additional criteria for distinguishing natural, treated and synthetic pink diamonds and to find a correlation with the “EGL USA CIS (Cross-reference Identification System) fluorescence method”. 相似文献
24.
Slavica Siler-marinkovic Ljiljana Mojovic Violeta Davinic Branko Bugarski 《Drug development and industrial pharmacy》1997,23(5):483-488
Liposome are promising drug carrier systems being developed. Their successful use in the treatment of several diseases demonstrates that a solid rationale for clinical development of liposomes as antimicrobial drug carriers can be established. There are a number of potential drug candidates for liposome encapsulation. The involvement of several biotechnology companies has culminated in the design and licensing of formulations for the treatment of certain microbial infections and cancers. Understanding of liposome behavior in the body and of the physicochemical mechanisms involved in the interaction of liposome, drug, and cellular targets is essential for their future applications. 相似文献
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Rheological properties of hydroxyl‐terminated and end‐capped aliphatic hyperbranched polyesters
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Branko Dunjic Srba Tasic Branislav Bozic Vesna Aleksandrovic‐Bondzic Marija S. Nikolic Jasna Djonlagic 《应用聚合物科学杂志》2015,132(7)
The rheological behavior of two series of aliphatic hyperbranched (HB) polyesters, based on 2,2‐bis(hydroxymethyl)propionic acid (bis‐MPA) and di‐trimethylol propane (Di‐TMP) as a tetrafunctional core, was studied. The effect of the size (pseudo‐generation number, from second to eight) and structure on the melt rheological properties was investigated for a series of hydroxyl‐terminated HB polyesters. In addition, the influence of the nature and degree of modification of the terminal OH groups in a series of fourth‐generation polyesters end‐capped with short and long alkyl chains and some aryl groups on the rheological properties was analyzed. The time–temperature superposition procedure was applied for the construction of master curves and for the analysis of the rheological properties of HB polyesters. The data obtained from WLF analysis of the HB polyesters showed that the values of the thermal coefficient of expansion of free volume αf and the fractional free volume at the glass transition temperature, fg, increase with increasing size of the HB polyesters. It was shown that the modified HB polyesters exhibited lower Tg and TG′=G″ temperatures, above which viscous became dominant over elastic behavior. From an analysis of the master curves of the modified HB polyesters, it was observed that with increasing degree of modification, both storage and loss modules and complex dynamic viscosity and apparent energy for viscoelastic relaxation decrease, because of reduced intermolecular hydrogen interactions. They do not exhibit a plateau of rubbery behavior, which confirms that no entanglements are present and that the molar masses are below the critical molar mass. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41479. 相似文献
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Thermophoretic and electrophoretic coatings are the main viable mechanisms for the coating of objects with nanoparticles. Unlike electrophoretic coating, thermophoretic coating has the advantage that electrically conductive substrates are not a requirement. This paper investigates the thermophoretic deposition and uniformity of molybdenum oxide nanoparticles, generated by a glowing wire generator, on various surfaces at three different flow rates (0.3, 1 and 1.5 L min–1). The quantitative evidence of the presence of particles collected by a suggested thermophoretic precipitator at different flow rates has shown that a uniform distribution of the particles could be achieved across the whole area of the precipitator. SEM and TEM micrographs of the film confirmed that a homogeneous densely packed network of molybdenum oxide nanoparticles was built across the precipitation area at the flow rate of 1.5 L min–1. 相似文献
29.
详细地介绍了α-磺基脂肪酸甲酯(SME)优良的发泡力、去污力及水溶性。SME的诸多特性使它成为普通及超浓缩餐具洗涤剂的理想原料。介绍了SEM的制备工艺以及基于SME的配方特性。 相似文献
30.
Downie J.D. Tomkos L. Antoniades N. Boskovic A. 《Lightwave Technology, Journal of》2002,20(2):218-228
We report computer simulation results of the effects on optical signal quality of passage through a cascade of wavelength division multiplexing (WDM) filters-multiplexers and demultiplexers-for directly modulated lasers with different chirp characteristics. In particular, lasers with transient or adiabatic chirp characteristics at 2.5 Gb/s and 10 Gb/s are investigated, and we find clear differences between the laser types with respect to filter concatenation effects. Filters with an optical bandwidth suitable for a 200-GHz channel-spacing system are considered, and we evaluate the system behavior as a function of laser frequency offset for a fixed number of filters. The reference network architecture used for the simulations is an optically transparent metropolitan scale network in which the WDM signals may be demultiplexed and then multiplexed again at multiple optical network elements. The signal quality is evaluated in terms of a distortion-induced eye-closure penalty as well as the excess attenuation or loss suffered. We find that transient chirp-dominated lasers show a generally symmetric distortion penalty response to laser frequency offset, whereas the response for adiabatic chirp dominated lasers is highly asymmetric. Furthermore, the extinction ratio for the latter class of lasers can be improved, in some cases, by the appropriate offset between laser and filter center frequencies 相似文献