Quantification of powder holdups in the presence of a cavity with lateral gas–powder injection in a packed bed

The lateral flow of gas–powder through a packed bed in a cold model is studied to understand the flow and holdup behaviour of powder in the presence of a cavity, nozzle (tuyere) protrusion, and decreasing gas condition, a system used in the ironmaking blast furnace. Experiments conducted in the current study included a two-dimensional (2D) slot-type packed bed. A previously published mass balance and elutriation velocity concept formed the basis for accurately quantifying the static and dynamic powder holdups. Experiments conducted under different conditions such as powder size and flux, gas flow rate, and packed particle density and size resulted in quantifying the powder holdups. The pressure drop in both horizontal and vertical directions is studied in all two-phase flow experiments. The formation of the static holdup with time in the packed bed is studied. The reproducibility of the experiments was confirmed. The static holdup inside the packed bed at various locations along the vertical direction (i.e., height) is also quantified. The static holdup correlation developed based on experimental data resulted in a 95% confidence interval. Static powder holdup increases with a decrease in the superficial gas velocity, an increase in the size of the powder particle, and powder flux. Dynamic holdup also showed a similar trend.     

House of Cards Nanostructuring of Graphene Oxide and Montmorillonite Clay for Oil–Water Separation

Noncovalent interactions are ubiquitous in our daily living. Nature employs hydrophobic effects, π–π interactions, hydrogen bonding, van der Waals forces, and electrostatic interactions in many biological processes such as protein folding. In the same manner, scientists exploit this plethora of inherently reversible noncovalent interactions as dials to design robust and smart materials. Electrostatic interaction is particularly interesting due to the simplicity of its concept, i.e., opposite charges attract. However, to our knowledge, the electrostatic interaction between two different 2D nanomaterials has not been investigated in literature. A myriad of natural and synthetic 2D nanomaterials should be explored for what may be an exciting cocktail of synergistic and tunable properties brought about by their charges and physical properties. This contribution highlights an interesting phenomena when organic, negatively charged graphene oxide and inorganic, positively charged montmorillonite (MMT) clay edges are brought into contact.     

Hydrocarbon storage modeling for diesel oxidation catalysts

A simple hydrocarbon (HC) storage model was proposed which represents the adsorption-desorption processes in zeolites incorporated in a diesel oxidation catalyst (DOC). Using four experiments in which the HC was stepped up and the reactor run until steady state, a Langmuir isotherm was generated that was sufficient to represent the equilibrium data, and the remaining rate constant capturing the adsorption time scale was obtained by fitting. The model thus developed was validated using reactor data which was obtained by stepping the inlet HC concentration to zero after outlet reached equilibrium.A typical DOC which contained both a storage component (zeolite) and noble metal component (for oxidation) was studied using a full scale 1D reactor model which includes the storage kinetics developed here with the oxidation kinetics developed in our previous work [Sampara et al., 2008. Global kinetics for a commercial diesel oxidation catalyst with two exhaust hydrocarbons. Industrial & Engineering Chemistry Research 47, 311-322]. Simulations of a simplified warm-up process indicated that the zeolite storage component reduces the overall cold start HC emissions by at least a factor of two if the warm-up rate achieves , a range commonly observed during start-up. Modeling results also showed that the HC oxidation for these reactors commonly starts at the rear end of the reactor due to reduced CO inhibition. The rates of the individual processes during cold start were analyzed in detail and compared with the rate of inlet temperature increase provided from the exhaust.     

Improving delamination resistance of carbon fiber reinforced polymeric composite by interface engineering using carbonaceous nanofillers through electrophoretic deposition: An assessment at different in-service temperatures

In this article, modification of carbon fiber surface by carbon based nanofillers (multi-walled carbon nanotubes [CNT], carbon nanofibers, and multi-layered graphene) has been achieved by electrophoretic deposition technique to improve its interfacial bonding with epoxy matrix, with a target to improve the mechanical performance of carbon fiber reinforced polymer composites. Flexural and short beam shear properties of the composites were studied at extreme temperature conditions; in-situ cryo, room and elevated temperature (−196, 30, and 120°C respectively). Laminate reinforced with CNT grafted carbon fibers exhibited highest delamination resistance with maximum improvement in flexural strength as well as in inter-laminar shear strength (ILSS) among all the carbon fiber reinforced epoxy (CE) composites at all in-situ temperatures. CNT modified CE composite showed increment of 9% in flexural strength and 17.43% in ILSS when compared to that of unmodified CE composite at room temperature (30°C). Thermomechanical properties were investigated using dynamic mechanical analysis. Fractography was also carried out to study different modes of failure of the composites.     

Dimethylamine-modified waste paper for the recovery of precious metals

Waste newsprint paper was modified with dimethylamine (DMA) to obtain a tertiary amine type adsorption gel called DMA-paper gel. This new derivative was investigated for adsorption, from hydrochloric acid medium, of gold, palladium, and platinum as well as some base metals. The gel exhibited selectivity only for precious metals with a remarkably high capacity for Au(III), i.e., 4.6 mol/kg dry gel and comparable capacities, i.e., 2.1 and 0.9 mol/kg for Pd(II) and Pt(IV), respectively. Also, Au(III) was reduced to the elemental form during adsorption. Furthermore, column adsorption and subsequent elution of the adsorbed metal ions by acidic thiourea revealed encouraging recoveries (approximately 90%), thus enhancing the scope of the gel for effective preconcentration, separation, and recovery of precious metals. The effectiveness of recovery of precious metals from real industrial liquor was also tested, and it showed highly encouraging results with respect to the stability of the gel in the harsh medium, and selectivity for the targeted metal ions in the presence of excess of other metal ions.     

Nitrites Derived From Foneiculum Vulgare (Fennel) Seeds Promotes Vascular Functions

Abstract: Recent evidence has demonstrated that nitrites play an important role in the cardiovascular system. Fennel (Foneiculum vulgare) seeds are often used as mouth fresheners after a meal in both the Indian sub‐continent and around the world. The present study aims to quantify the nitrite and nitrates in fennel seeds as well as elucidating the effect of fennel derived‐nitrites on vascular functions. Results from our study show that fennel seeds contain significantly higher amount of nitrites when compared to other commonly used post‐meal seeds. Furthermore our study confirmed the functional effects of fennel derived‐nitrites using in vitro and ex vivo models that describe the promotion of angiogenesis, cell migration, and vasorelaxation. We also showed that chewing fennel seeds enhanced nitrite content of saliva. Thus our study indicates the potential role of fennel derived‐nitrites on the vascular system. Practical Application: This study is focused on determining the effect of fennel‐derived nitrites on angiogenesis (the formation of new blood vessels from pre‐existing ones), cell migration, and vasorelaxation (dilation of blood vessels) thereby preserving cardiovascular health.     

Mathematics for reasoning about loop functions

The criticality of modern software applications, the pervasiveness of malicious code concerns, the emergence of third-party software development, and the preponderance of program inspection as a quality assurance method all place a great premium on the ability to analyze programs and derive their function in all circumstances of use and all its functional detail. For C-like programming languages, one of the most challenging tasks in this endeavor is the derivation of loop functions. In this paper, we outline the premises of our approach to this problem, present some mathematical results, and discuss how these results can be used as a basis for building an automated tool that derives the function of while loops under some conditions.     

Entanglement in two-site Bose–Hubbard model with non-linear dissipation

In this paper, we study the decoherence and entanglement properties for the two-site Bose–Hubbard model in the presence of a non-linear damping. We apply the techniques of thermo field dynamics and then use Hartree-Fock approximation to solve the corresponding master equation. The expectation values of the approximated field operators appearing in the solution of master equation are computed self-consistently. We solve this master equation for a small time t so that we get the analytical solution, thereby we compute the decoherence and entanglement properties of the solution of the two-mode bosonic system. We have found that for a small initial time t, the entanglement of the system increases but at the same time the system decoheres exponentially.     

Study of Temperature Dependence of Electrode–Glass Ceramic Interface Using Impedance Spectroscopy

The electrical behavior of strontium titanate borosilicate glass ceramics (SrO.TiO₂- 2SiO₂.B₂O₃) with additives K₂O, La₂O₃, CoO and Nb₂O₅ was studied by using Impedance Spectroscopy as a function of temperature and composition. An equivalent circuit model having three parallel RC's connected in series with a capacitor C₄ could represent the data well. By comparing the complex modulus plots with simulated ones and looking at the values of the time constants these RC's were attributed to represent crystalline, glassy and glass-crystal interface regions of the glass- ceramic whereas C₄ represented the glass-ceramic sample and contact electrode interface. When the glass ceramic sample contained only SrTiO₃ crystalline phase and the remaining glassy matrix, the interface capacitance showed an Arrhenius type of nature with an activation energy (0.11 ± 0.04) eV and when the glass- ceramic sample contained number of crystalline phases no clear cut trend appeared. These findings are useful in selecting suitable electrodes for applications as well as in deciding upon experimental techniques for measurement of dielectric constants of materials.     

Improved phase estimation based on complete bispectrum and modified group delay

In this paper, a new method for extracting the system phase from the bispectrum of the system output has been proposed. This is based on the complete bispectral data computed in the frequency domain and modified group delay. The frequency domain bispectrum computation improves the frequency resolution and the modified group delay reduces the variance preserving the frequency resolution. The use of full bispectral data also reduces the variance as it is used for averaging. For the proposed method at a signal to noise ratio of 5dB, the reduction in root mean square error is in the range of 1.5–7 times over the other methods considered.