Study of the mechanism of pore diffusion in batch adsorption systems

In this study the film-pore diffusion model was applied to describe system transport kinetics of three basic dye-carbon systems, namely Basic Blue 69, Basic Red 22 and Basic Yellow 21. The mass transfer parameters evaluated were the external mass transfer coefficient k_f (cm s^?1) and the effective diffusivity D_eff (cm² s^?1). A single k_f value was sufficient to describe each dye system: these were 0.15 × 10^?2, 0.20 × 10^?2 and 0.50 × 10^?2 cm s^?1 for BB69, BR22 and BY21, respectively. The effective diffusivity was found to have values much larger than those of pore diffusivities calculated from liquid diffusivities and its value decreased with increasing initial dye concentration. This was attributed to the effect of surface diffusion, hence pore diffusivity was exchanged by the effective pore diffusivity in the model. The present model was solved by the exponential curve fit technique; results were expressed in the form of experimental and theoretical Sherwood Numbers compared in terms of the residual.     

Supercritical water oxidation of quinoline in a continuous plug flow reactor—part 2: kinetics

The results of a detailed investigation into the kinetics of quinoline oxidation in supercritical water are presented. The novel kinetic data presented were obtained in a continuously operated, plug flow reactor where parameters such as temperature, pressure, residence time and stoichiometric ratio of oxidant to quinoline were investigated and detailed in the companion paper (Pinto LDS, Freitas dos Santos LMF, Al‐Duri B and Santos RCD, Supercritical water oxidation of quinoline in a continuous plug flow reactor—part 1: effect of key operating parameters. J Chem Technol Biotechnol). An induction time was experimentally observed, ranging from 1.5 to 3.5 s, with longer times observed in experiments carried out at lower temperatures. A pseudo‐first‐order rate expression with respect to quinoline concentration (with oxygen excess) was first adopted and the activation energy of 234 kJ mol^?1 and a pre‐exponential factor of 2.1 × 10¹⁴ s^?1 were estimated. Furthermore, an integral power rate model expression was established, attributing a reaction order for quinoline as 1 and for oxygen as 0.36. An activation energy and pre‐exponential factor for this model were determined as 224 kJ mol^?1 and 3.68 × 10¹⁴ M^?0.36 s^?1, respectively. A global rate expression was then regressed for the quinoline reaction rate from the complete set of data. The resulting activation energy was 226 ± 19 kJ mol^?1 and the pre‐exponential factor was 2.7 × 10^{13 ± 2} M^?0.1 s^?1. The reaction orders for quinoline and oxygen were 0.8 ± 0.1 and 0.3 ± 0.1, respectively. It was shown that the least‐squares regression method provided the best‐fit model for experimental results investigated in this study. Copyright © 2006 Society of Chemical Industry     

Legal and institutional perplexities hampering the implementation of urban development plans in Pakistan

The effective implementation of development plans requires functioning institutions with well defined legal support and good plans. This article explains how legal and regulatory frameworks as well as the institutional capacities of local planning agencies (LPAs), including Cantonment Boards (CBs), City District Governments (CDGs), Town Municipal Administration (TMAs) and Development Authorities (DA), in Pakistan confound and affect the implementation of development plans. A comparative review of existing Acts, Ordinances and urban planning frameworks in place at various levels was conducted, and inconsistencies and gaps that impart perplexities amongst the aforementioned institutions and regulatory frameworks were identified. The overlapping powers and functions of the institutions which have legal backing must be eliminated to ensure effective implementation of urban development plans.     

Synthesis of polyaniline based composite material and its analytical applications for the removal of highly toxic Hg<Superscript>2+</Superscript> metal ion: Antibacterial activity against <Emphasis Type="Italic">E. coli</Emphasis>

A composite material polyaniline-Zr(IV) phosphoborate (PZPB) was synthesized via sol-gel method by the combination of Zr(IV) phosphoborate and polyaniline. The PZPB composite material was characterized by various analytical techniques. The PZPB composite material was found to be selective for Hg²⁺+ metal ion due to the high distribution coefficient values for Hg²⁺+ metal ion in all mediums. The PZPB composite material was used for Hg²⁺+ removal under different experimental conditions. The antibacterial activity of PZPB composite material was also studied against E. coli.     

Turbulent flow in a machine honed rough pipe for large Reynolds numbers: General roughness scaling laws

An alternate inner wall variable, for flow over a transitional rough pipe surface, is defined as the ratio of normal coordinate measured above the mean roughness level to the wall roughness scale. The Reynolds equations for mean turbulent flow in a transitional rough pipe, in two layers (inner and outer) are considered. The predictions of the mean velocity and friction factor in fully developed turbulent flow in a rough pipe flow, presented here, covers all types of roughness. The data for a particular case of the machine honed Princeton superpipe roughness, analogous to inflectional type roughness of Nikuradse, is presented, as two expressions using our roughness scale. The velocity profile and friction factor, on a transitional rough wall, are shown to be governed by the new log laws, which are explicitly independent of the transitional wall roughness. Further, the inflectional roughness has also been connected with geometric roughness parameters; like, arithmetic mean roughness, mean peak to valley heights roughness, root mean square (rms), roughness based on texture measure; and the friction factor implicit and approximate explicit formulas have also been proposed. In entire transition region between fully smooth and fully rough wall, monotonic roughness of Colebrook (Moody Chart) over estimaton the friction factor when compared with present inlectional roughness.     

Discovering Non-Cooperating Nodes by Means of Learning Automata in the Internet of Things

Internet of Things (IoT) refers to a set of things that are wirelessly connected. The lack of cooperation of nodes, which is due to the reduction of energy level, leads to non-cooperating nodes. Discovering non-cooperating nodes is regarded as one of the main challenges of IoT. In this paper, we addressed this issue by using learning automata where misbehavior of non-cooperating nodes is identified and removed from the network. Simulation results of the proposed method were compared with those of previous works and methods; it was found that the proposed method optimized the other methods in terms of power consumption, throughput, the precision of discovering non-cooperating nodes, and false-positive rate.

     

A study of the influence of crystallite size on the electrical and magnetic properties of CuFe2O4

An attempt has been made to clarify the fundamental assumption that the properties of materials change as the crystallite size of the material is reduced below 100 nm. CuFe₂O₄ samples of different crystallite sizes were prepared by the sol–gel and combustion methods and then analyzed by X-ray diffraction (XRD), thermal analyses (TGA/DTG) and scanning electron microscopy (SEM) techniques. The magnetic properties were studied by measuring the AC magnetic susceptibility (χ) and the Mössbauer spectroscopy. The DC electrical resistivity, dielectric constant, dielectric loss tangent, Curie temperature and hyperfine splitting of the samples change with the crystallite size. The change in the electrical properties is attributed to the formation of discrete energy levels instead of the bands. However, the magnetic parameters change due to the existence of non magnetic surface layers. The isomer shift and the hyperfine splitting show gradual increase with the increase in crystallite sizes.     

Correction to: Deposition of bismuth sulfide and aluminum doped bismuth sulfide thin films for photovoltaic applications

Journal of Materials Science: Materials in Electronics -     

Stimulation of secondary metabolites by copper and gold nanoparticles in submerge adventitious root cultures of Stevia rebaudiana (Bert.)

Nanotechnology is one of the advance technologies that almost found implications in every field of science. The importance is due to the unique properties of nanoparticles. In this study, bimetallic alloys of copper (Cu) and gold (Au) were tested in submerge root cultures of Stevia rebaudiana for production of biomass and secondary metabolites. A known amount of inoculum roots were submerged in liquid Murashige and Skoog medium containing combination of naphthalene acetic acid (NAA; 0.5 mg l⁻¹) and different ratios of nanoparticles (NPs). NAA augmented medium was used as control. The addition of nanoparticles (30 µg l⁻¹) stimulated biomass accumulation (1.447 g/flask) on 27th day of log phases. The maximum total phenolics content (TPC; 16.17 mg/g‐DW) and total flavonoids content (TFC; 4.20 mg/g‐DW) were displayed using AuCu‐NPs (1:3) and NAA. The same combinations enhanced total phenolic production (TPP; 116 mg/L) and total flavonoid production (TFP; 29.5 mg/L) in submerged cultures. A strong correlation was observed between phenolics, flavonoids and dry biomass. Moreover, maximum 1, 1‐diphenyl‐2‐picrylhydrazyl (DPPH) activity of 79% was displayed by addition of AuCu (1:3) nanoparticles. In conclusion, nanoparticles application has shown a positive effect in enhancing biomass and secondary metabolites production in adventitious root cultures of Stevia rebaudiana.Inspec keywords: bimetals, copper, gold, nanoparticles, renewable materials, bioenergy conversion, toxicology, nanofabrication, nanobiotechnology, biochemistry, molecular biophysicsOther keywords: Au‐Ag, time 27 d, maximum DPPH activity, dry biomass, flavonoids, phenolics, NAA enhanced total phenolic production, total flavonoid content, maximum total phenolic content, log phases, bimetallic NPs stimulated biomass accumulation, NAA augmented medium, naphthalene acetic acid, Skoog medium, liquid Murashige, inoculum roots, culture development, seed‐derived roots, bimetallic alloys, nanotechnology, Stevia rebaudiana (Bert.), submerge adventitious root cultures, gold nanoparticles, copper nanoparticles, secondary metabolites     

Novel Positive Multi-Layer Graph Based Method for Collaborative Filtering Recommender Systems

Recommender systems play an increasingly important role in a wide variety of applications to help users find favorite products. Collaborative filtering has remarkable success in terms of accuracy and becomes one of the most popular recommendation methods. However, these methods have shown unpretentious performance in terms of novelty, diversity, and coverage. We propose a novel graph-based collaborative filtering method, namely Positive Multi-Layer Graph-Based Recommender System (PMLG-RS). PMLG-RS involves a positive multi-layer graph and a path search algorithm to generate recommendations. The positive multi-layer graph consists of two connected layers: the user and item layers. PMLG-RS requires developing a new path search method that finds the shortest path with the highest cost from a source node to every other node. A set of experiments are conducted to compare the PMLG-RS with well-known recommendation methods based on three benchmark datasets, MovieLens-100K, MovieLens-Last, and Film Trust. The results demonstrate the superiority of PMLG-RS and its high capability in making relevant, novel, and diverse recommendations for users.