Simulation of a Combined Isomerization Reactor & Pressure Swing Adsorption Unit

The Total Isomerization Process developed by Union Carbide in 1970 (Gary, 1987) for the conversion of normal paraffin's to their isomers consists of a reactor followed by a PSA unit each operating at similar pressures and temperatures. The combination of these two operations in one unit in a Pressure Swing Adsorption Reactor (PSAR) process may provide an increased throughput and a significant cost saving in ancillary equipment.The simulation of a mathematical model linking the catalyst packed-bed and the adsorbent packed-bed is reported. The catalyst is a Pd/Y-zeolite and the adsorbent is 5A zeolite. The simulated feed consists of 17% each of n- and isopentane with the remainder being hydrogen. The mathematical model assumes dispersed plug-flow in both sections, constant velocity in the reactor section but varying in the adsorber, with mass transfer in the adsorber section due to external fluid film resistance and macropore diffusion in series. The fraction of the total column length occupied by the catalyst (denoted by ) is accounted for in the model by solving numerically using orthogonal collocation on finite elements. Parameters varied are the ratio of catalyst/column length (), temperature range (506–533 K), high pressure (15–20 bars), with the low pressure held constant at 2 bars. The catalyst/column ratio has a strong effect at low temperatures. The optimum catalyst/column length ratio appears to be controlled by the low pressure step and occurs at = 0.7 for the assumptions used in this work.     

Landau's theorem for biharmonic mappings

In this paper, we show the existence of Landau constant for biharmonic mappings of the form F(z)=²|z|G(z)+K(z), |z|<1, where G and K are harmonic.     

Experimental investigation into the effect of heat transfer on compressible air stream in a duct

A converging nozzle-constant area parallel passage with an outer duct encasing the constant-area passage has been built for investigating the effect of heat transfer on subsonic flow of an air stream. It is concluded experimentally as can be predicted analytically that large quantities of heat are needed in order to accelerate very slow air stream (incompressible) to sonic conditions. It is observed experimentally as confirmed analytically, that the increase in Mach number with heat addition is associated with a decrease in the local static pressure along the axis of the duct. It could be concluded that any more heat added beyond thermal choking will be accompanied by a decrease in the mass flow rate of the compressible flowing air.Nomenclature A cross-sectional area of the duct - C _{P air} specific heat of air joules/kg. °K - C _d discharge coefficient - D duct diameter - d orifice diameter m - dA _d elemental lateral area of the duct - h overall heat transfer coefficient - h head across orifice, mm. - M Mach number - m _air mass flow rate of air - P local static pressure - P _b back pressure at duct outlet - P ₀₁ stagnation pressure at duct inlet - gas density - _u air density upstream of orifice - _q incremental heat flow - T local static temperature - T ₀₁ stagnation temperature at duct inlet - T _h hot water temperature - q heat added per kg of flowing air - V flow speed     

2-pyrrolidone - capped Mn<Subscript>3</Subscript>O<Subscript>4</Subscript> nanocrystals

Water-soluble Mn₃O₄ nanocrystals have been prepared through thermal decomposition in a high temperature boiling solvent, 2-pyrrolidone. The final product was characterized with XRD, SEM, TEM, FTIR and Zeta Potential measurements. Average crystallite size was calculated as ∼15 nm using XRD peak broadening. TEM analysis revealed spherical nanoparticles with an average diameter of 14±0.4 nm. FTIR analysis indicated that 2-pyrrolidone coordinates with the Mn₃O₄ nanocrystals only via O from the carbonyl group, thus confining their growth and protecting their surfaces from interaction with neighboring particles.      

A green chemical route for the synthesis of Mn3O4 nanoparticles

A novel environmental friendly, room temperature route using an ionic liquid 1-n-butyl-3-methylimidazolium hydroxide ([BMIM]OH) for the synthesis of Mn₃O₄ nanoparticles is presented. The product was characterized using Fourier transform infrared spectroscopy, X-ray powder diffraction, and transmission electron microscopy. Phase purity was confirmed by XRD, and X-ray line profile fitting determined a crystallite size of 42 ± 11 nm. TEM analysis revealed various morphologies. EPR measurements have indicated the existence of long-range interactions, due to the wide range of particle sizes and morphologies observed.      

On the univalence of functions with logharmonic laplacian

In this paper, we prove Radó’s theorem holds for functions of the form is logharmonic. We show that if F is of the form , where is logharmonic, then F is starlike iff ψ(z)=h(z)/g(z) is starlike. In addition, when , where L is logharmonic and H is harmonic, we give the sufficient conditions for F to be locally univalent.     

Integral means and arclength inequalities for typically real logharmonic mappings

In this paper, we use star functions to conclude the integral means inequalities for typically real logharmonic mappings. Moreover, we determine the upper bound for the arclength of typically real logharmonic mappings.     

Landau’s theorem for functions with logharmonic Laplacian

In this paper, we show the existence of Landau constant for functions with logharmonic Laplacian of the form F(z) = ∣z∣²L(z) + K(z), ∣z∣ < 1, where L is logharmonic and K is harmonic. Moreover, the problem of minimizing the area is solved     

A Multi-crosslinking Nanocapsule-Based Serial-Stimuli-Responsive Leakage-Free Drug-Delivery System In Vitro

As some stimuli utilized in conventional drug delivery systems can also be found in normal cells, it is inevitable that encapsulated drugs escape from carriers into normal cells. Based on mutual interactions among proteins, polyphenol compounds, and metal ions, we developed a serial-stimuli-responsive drug delivery system. With multi-crosslinking structure, nanocapsules can maintain the integrity of the framework, even with a certain amount of stimuli present, and eventually reach tumor cells to initiate apoptosis, and protect normal cells from being damaged. Meanwhile, the fluorescence of DOX will be quenched when encapsulated in nanocapsules. This property means that the DOX that is released from nanocapsules can be monitored in real-time based on the recovery of fluorescence. These versatile nanocapsules exhibit great potentials to treat cancer.