The fluorescence and fluorescence excitation spectra of pure and doped polycarbonate (PC) depending on hindered-amine light stabilizers (HALS: Tinuvin 770 and Tinuvin 123) concentration and different processing conditions have been studied. Non-processed PC has no emission band in the visible range but processed PC with additives show visible fluorescence bands between 400–470 nm. It suggested that PC undergoes a kind of degradation process which lead to the fluorescence emission caused by the transitions from the new distortion-related localized states (defect states) created by processing and the additives. Such defects lead also to the emergence of a new band in the excitation and emission spectra at lower energies, where the symmetry of the bands break near. The intensity of these bands drastically depends on the sample treatment where the luminescence intensity quantitatively characterizes the concentration of defect radicals. An increase in screw speed resulted in an increase in specific mechanical energy (SME), higher SME led to a remarkable macromolecular degradation.
The motion of the charged particles in graphene in the frame of the quantum non-local hydrodynamic description is considered. It is shown as results of the mathematical modeling that the mentioned motion is realizing in the soliton forms. The dependence of the size and structure of solitons on the different physical parameters is investigated.
Solar variability affects Earth climate. It is proposed that this forcing primarily goes via the interaction of the Solar Wind with the Earth’s magnetosphere, rather than via changes in irradiance, which is generally assumed. The cyclic variations in Solar Wind emission generate corresponding changes in the Earth’s rate of rotation (LOD), as recorded by correlations between sunspot numbers and LOD-variations. Variations in Earth’s rotation affect not only the atmospheric circulation but also the ocean circulation. Because the ocean water has a very high heat storing capacity, changes in the ocean circulation will affect regional climate. The redistribution of oceanic water masses also gives rise of irregular changes in sea level over the globe. During the last 6000 years this redistribution of ocean water masses seems to have been the dominate sea level variable. The El Niño/ENSO events contain a part, which represent an interchange of angular momentum between the solid earth (LOD) and the equatorial ocean circulation in the Pacific. The 60-year solar-terrestrial cycle controlled the climatic conditions and main fish stocks in the Barents Sea via an oceanic beat in the inflow of warm Atlantic water. The major Solar Maxima and Minima of the last 600 years correspond to decreases and increases in the Earth’s rotation, which altered the ocean circulation in the North Atlantic by that generating major climatic changes and sea level changes. Speeding-ups of the Earth’s rotation during the Spörer, Maunder and Dalton Solar Minima forced the Gulf Stream to be concentrated on its southern branch and cold Arctic water to penetrate far down along the European coasts, which lead to Little Ice Age conditions in the Arctic and in northern to middle Europe but extra warm periods in the Gibraltar to northwest African region. During the Solar Maxima, the situation was the reverse. By around 2040, we will be in a new major Solar Minimum and may, therefore, expect a period of cold climatic conditions.
We have simulated the Chalcogenide glass (ChG)-based nanostructures which are used as substrates for surface-enhanced Raman scattering (SERS). A discrete dipole approximation method was used and calculated results are compared to those of experimental. The results of simulation agreed well with the experiment. Furthermore, we have obtained conditions under which higher enhancement factors (almost by an order of magnitude) could be achieved by changing the polarization state and the incident angle of the beam on the surface.
This study was carried out to assess the fuel quality of biodiesel produced from tigernut (Cyperus esculentus) oil and its blends with petro- diesel. The oil was extracted from the tigernut by solvent extraction method using petroleum ether. The oil was trans-esterified using potassium methoxide at the temperature of 60ºC for 60 min at a catalyst concentration of 0.65% and under a constant stirring speed. The crude biodiesel obtained was purified by washing with water and subsequently dried in an oven. The biodiesel was again blended with petro- diesel to obtain various blends of B10, B20, B30 and B40. Oil and biodiesel yields were assessed while physicochemical analysis of the oil, biodiesel and blends were carried out using standard methods for physicochemical parameters including flash point, cloud point and pour point. Results obtained showed that the oil yield from the feedstock was 16%, while the biodiesel yield was 82%. The high and moderate flash points of the biodiesel and blends ranged between 90-178ºC, their cloud points ranged between 6.5-13ºC while their pour points ranged between -3-(-10)ºC. General results of the blends showed that B10 and B20 had performance results closer to petro-diesel and ASTM standards. Therefore, the blends, in addition to being good for biodiesel engines, would also be suited for engines not specifically designed for biodiesel use.
The investigation of the variability of the Sq(H) in the African sector was carried out using the geomagnetic field measurements of four stations located in the East, West, Central and South Africa. The study shows that the variations of the geomagnetic element were a dusk to dawn phenomenon with a none zero variation observed in the night. The variability of the nighttime Sq(H) is believed to be from sources other than the ionosphere. An enhancement in Sq(H) variations in Addis Ababa station was observed. The observed enhancement in Sq (H) variations in Addis Ababa station was attributed to the influence of Equatorial electro jet [EEJ] current system. Day- to-day variability in Sq(H) was observed in all the stations, these variability from one day to the next was seen to be both in amplitude and in phase, it does not have a definite pattern thus it is random. Equinoctial maximum in Sq(H) was observed for Mbour, Addis Ababa and Bangui stations while December Solstitial maximum was observed for Hermanus station. Latitudinal positions of the stations were found to affect the Sq(H) amplitude.