Gas-liquid chromatographic determination of the gaseous products of the two-stage pyrolysis of heavy oils

The two-stage pyrolysis of fuel oil and vacuum residues separated from Egyptian crude oil have been carried out using a batch-type reactor technique. In the first stage, feedstocks undergo catalytic cracking in the presence of platinum as a catalyst at temperatures ranging between 380 and 460 °C and 440 and 520 °C for fuel oil and vacuum residues, respectively. Products are carried by argon gas for subsequent pyrolysis in the second stage at temperatures ranging between 700 and 820 °C and 700 and 800 °C for fuel oil and vacuum residues, respectively. The gas yields are about 94.1 and 82.0 wt% of the total products. The gases comprise saturated (C₁----C₅) and unsaturated hydrocarbons (ethylene, propylene, and butenes). By using platinum wire in the pyrolysis of fuel oil, the ethylene yield increases slightly as the temperature of the first stage increases, while it remains almost unchanged in the pyrolysis of vacuum residue. On the other hand, the propylene yield decreases slightly as the temperature of the first stage increases in the two feedstocks. By using a platinum sheet, the ethylene yield is doubled under the same conditions and increases slightly with an increase of temperature in the second stage. On the other hand, the propylene yield varies inversely with the temperature of the second stage by using platinum, whether as wire or sheet, although the yield is higher when platinum sheet is used under the same conditions.     

A proposed unsteady bioconvection model for transient thin film flow of rate-type nanoparticles configured by rotating disk

Journal of Thermal Analysis and Calorimetry - The revolution in nanotechnology has made new developments toward enhancement of energy resources which play a substantial role in the growth of...     

Thermodynamic potential of a high-concentration hybrid photovoltaic/thermal plant for co-production of steam and electricity

Journal of Thermal Analysis and Calorimetry - A thermodynamic model was developed to assess the energetic performance of a dual receiver concentrated photovoltaic/thermal plant for the...     

Mn3−xFexO4 Hollow Nanostructures for High-Performance Asymmetric Supercapacitor Applications

Design of hollow nanostructure and controllable phase of mixed metal oxides for improving performance in supercapacitor applications is highly desirable. Here we demonstrate the rational design and synthesis of Mn_3−xFe_xO₄ hollow nanostructures for supercapacitor applications. Owing to high porosity and the specific surface area that provides more active sites for electrochemical reactions, the electrochemical performance of Mn_3−xFe_xO₄ hollow nanostructure substantially enhanced comparing with pristine Mn₃O₄. Particularly, in 1.0 M KOH electrolyte, Mn_0.16Fe_2.84O₄ with a typical diameter of 20 nm exhibits excellent specific capacitance of 2675, 2320, 1662, 987 F g⁻¹ at current densities of 1, 2, 5, 10 A g⁻¹, respectively, which is significantly superior to those of other transition metal oxides. Besides, an asymmetric supercapacitor is assembled by using Mn_0.16Fe_2.84O₄ and activated carbon as a positive and a negative electrode, respectively. Electrochemical results indicate a high energy density of 42 Wh kg⁻¹ at a power density of 0.75 kW kg⁻¹, which makes this hollow nanostructure a highly promising electrode for achieving high-performance next-generation supercapacitors.     

Limitwise monotonic sets of reals

We extend the limitwise monotonicity notion to the case of arbitrary computable linear ordering to get a set which is limitwise monotonic precisely in the non‐computable degrees. Also we get a series of connected non‐uniformity results to obtain new examples of non‐uniformly equivalent families of computable sets with the same enumeration degree spectrum.     

Localization properties of electronic states of one-dimensional Galois sequences

Galois sequences are aperiodic ordered structures, which have wide applications in many fields. In this paper, we study the electronic properties of the tight-binding model on Galois sequences. The energy spectra, wave functions and localization quantities are calculated. The results reveal that this model exhibits the Anderson localization feature.     

Successive Minima and Best Simultaneous Diophantine Approximations

We study the problem of best approximations of a vector by rational vectors of a lattice whose common denominator is bounded. To this end we introduce successive minima for a periodic lattice structure and extend some classical results from geometry of numbers to this structure. This leads to bounds for the best approximation problem which generalize and improve former results.     

Measurements of 27 elements in garden and lawn fertilizers using instrumental neutron activation analysis

Five locally available garden and lawn fertilizers were analyzed for elemental content using instrumental neutron activation analysis. The fertilizers were labeled as High Yield; Slow Release, 13-13-13; 16-8-4 and 28-4-4. The concentration ranges of the elements measured, in g/g, were: Ba<10-105; Br 0.55-272; Co 0.33-3.74; Cr 10.0-42.5; Cs0.09-1.02; Eu 0.05-0.42; Fe 1840-9830; Ga<1-4.6; Ge<0.1-1.23; Hf0.07-2.32; La 1.66-10.4; Na 57.6-3990; Nd<9; Ni<3-12.3; Rb 2.42-48.5; Sb 0.03-0.24; Sc 0.3-3.11; Se 2.68-10.2; Sm<0.4-2.13; Sr 21.7-214; Ta<0.01-0.052; Tb 0.05-0.28; Th 0.52-2.16; U 0.18-0.38; Zn 10.8-233 and Zr<1-8.95. Some of these elements are recognized as micronutritiens (e.g., Fe & Zn), and are necessary for plant growth. However, other elements may lead to undesirable environmental effects. The undiscriminating use of fertilizers, especially in home gardening, may result in the increase of toxic elements (Co, Cr, Se, Sb, Th, U etc.) in the underground water supply.     

A trace element study of commercial infant milk and cereal formulas

Three commercial infant milk formulas, one commercial infant cereal formula and one locally grown cereal used for infant feeding in Nigeria were analyzed for 17 trace elements, viz: Al, As, Br, Ca, Ce, Cl, Co, Cr, Fe, K, Mg, Mn, Na, Rb, Sb, Se and Zn. The commercial milk formulas contain adequate amounts of Ca, Cl, Co, Fe, K, Mg, Mn, Na and Zn, the locally grown cereal contains adequate amounts of Co, K, Mg, Mn and Zn and low in Ca, Cl, Fe and Na while the commercial cereal has adequate amounts of Ca, Cl, Co, K, Mg, Na and Zn. None of the samples analyzed was found to contain any elements up to threshold toxicity limits of concentrations.