Reaction Kinetics of Steam Reforming of n‐Butanol over a Ni/Hydrotalcite Catalyst

Pyrolytic lignin can be transformed to liquid transportation fuels by hydrotreatment, which requires hydrogen (H₂). Bio‐oil is a suitable renewable feedstock for H₂ production. Here, n‐butanol was chosen as a model compound representing alcohols in the bio‐oil aqueous fraction. H₂ production from steam reforming of n‐butanol was investigated in a fixed‐bed reactor using a commercial Ni/hydrotalcite catalyst. A plausible reaction pathway in the presence of Ni was discussed. An increase in reforming temperature, space time, and steam/carbon ratio in the feed enhanced the n‐butanol conversion and H₂ yield. Reaction kinetics was studied in the defined chemical control regime. The reaction order with respect to n‐butanol (one) and the activation energy were determined.     

Rationally designed oxaliplatin-nanoparticle for enhanced antitumor efficacy

Nanoscale drug delivery vehicles have been extensively studied as carriers for cancer chemotherapeutics. However, the formulation of platinum chemotherapeutics in nanoparticles has been a challenge arising from their physicochemical properties. There are only a few reports describing oxaliplatin nanoparticles. In this study, we derivatized the monomeric units of a polyisobutylene maleic acid copolymer with glucosamine, which chelates trans-1,2-diaminocyclohexane (DACH) platinum (II) through a novel monocarboxylato and O --> Pt coordination linkage. At a specific polymer to platinum ratio, the complex self-assembled into a nanoparticle, where the polymeric units act as the leaving group, releasing DACH-platinum in a sustained pH-dependent manner. Sizing was done using dynamic light scatter and electron microscopy. The nanoparticles were evaluated for efficacy in vitro and in vivo. Biodistribution was quantified using inductively coupled plasma atomic absorption spectroscopy (ICP-AAS). The PIMA-GA-DACH-platinum nanoparticle was found to be more active than free oxaliplatin in vitro. In vivo, the nanoparticles resulted in greater tumor inhibition than oxaliplatin (equivalent to 5 mg kg?1 platinum dose) with minimal nephrotoxicity or body weight loss. ICP-AAS revealed significant preferential tumor accumulation of platinum with reduced biodistribution to the kidney or liver following PIMA-GA-DACH-platinum nanoparticle administration as compared with free oxaliplatin. These results indicate that the rational engineering of a novel polymeric nanoparticle inspired by the bioactivation of oxaliplatin results in increased antitumor potency with reduced systemic toxicity compared with the parent cytotoxic. Rational design can emerge as an exciting strategy in the synthesis of nanomedicines for cancer chemotherapy.     

LaNiO3/g-C3N4 nanocomposite: An efficient Z-scheme photocatalyst for wastewater treatment using direct sunlight

The major findings in this report are (i) development of nanocomposite photocatalyst working through Z-scheme charge transfer pathway across the heterojunction, (ii) utilization of direct sunlight as the photo-source, and (iii) prospect of ligand-hole in photocatalysis through enhanced sub-band gap absorption. The photocatalysts, namely LaNiO₃, g-C₃N₄ and LaNiO₃/g-C₃N₄ nanocomposites were synthesized via facile route and were characterized for their structure, morphology, microstructure, texture, elemental mapping and surface oxidation states by using several physicochemical techniques. The photocatalytic performance of the nanocomposite was tested through the degradation of hazardous azo dye pollutants, namely reactive black 5 and methylene blue as well as the colorless antibiotic-pollutant tetracycline hydrochloride in aqueous solution in presence of natural sunlight with excellent recycling activity. The 10%LaNiO₃/g-C₃N₄ nanocomposite sample shows the best catalytic activity, degrading respectively 94%, 98.6% and 88.1% of reactive black 5, methylene blue and tetracycline hydrochloride in 60, 180 and 120 min. The photocatalytic activity of the nanocomposite phase is several times superior to that of the pure phases. The improvements of photocatalytic activity of g-C₃N₄ in the nanocomposite have been rationalized through the construction of direct Z-scheme heterojunction and suppression of electron–hole pair recombination efficiency. The enhanced photo-absorption of the nanocomposite can possibly be related to sub-bandgap absorption, which is associated to the midgap state originating from ligand-hole formation or defects in the structure. The photodegradation process is mediated through the formation of super oxide radical (^˙O₂^¯) and hole (h⁺) as the main responsible species.     

Attribute-Based Authenticated Group Key Transfer Protocol without Pairing

Wireless Personal Communications - Group key establishment protocol is the primary requirement of several group-ware applications, like secure conferences, pay per view, collaborative work space...     

A novel multi-dimensional multiple image encryption technique

Multimedia Tools and Applications - This paper proposes a novel secure and fast multiple image encryption technique to encrypt multiple images of arbitrary sizes. In the proposed technique, a group...     

Eco-Friendly Synthesis of Colloidal Silver Nanospheres,Nanorings, and Nanonetworks

Abstract

Colloidal silver nanospheres, nanorings, and nanonetworks were synthesized by the nanosecond pulsed laser ablation of a silver metal plate in a pure distilled water (at room temperature) using the fundamental (1064 nm), second harmonic (532 nm), and third harmonic (355 nm) wavelengths of the Nd:YAG laser, respectively. The products were characterized by means of both transmission electron microscopy (TEM) and optical absorption spectroscopy. The TEM data show the formation of silver nanospheres, nanorings, and nanonetworks. On the other hand, optical spectra reveal the occurrence of the red shift of the peak associated with the surface plasmon resonance (SPR) of silver nanorings and nanonetworks. A possible explanation for the formation of above stated silver nanostructures is being discussed.     

Simulation of a temperature drop for the flow of rarefied gases in microchannels

The Direct Simulation Monte Carlo (DSMC) method is widely used to study the flow characteristics of subsonic flow in 2-D microchannels. It is seen from existing numerical studies that the temperature of the flow decreases towards the exit of the microchannel whereas such a drop has not been reported in experimental studies. To resolve this discrepancy, effect of flow parameters such as Knudsen number, aspect ratio and pressure ratio on temperature change is studied systematically using an in-house developed DSMC code. Based on the parametric analysis, a correlation for temperature drop is proposed which predicts the DSMC data within ±15%. A control volume analysis is further carried out to understand the reason for temperature drop in microchannels. The effect of mass diffusion is also modeled. It is found that accounting for mass diffusion improves prediction of mass flow rate but not temperature drop across the microchannel.     

Kinetic investigation on butanol steam reforming over Ru/Al2O3 catalyst

Steam reforming of biomass-derived oxygenates is an attractive technique for the renewable production of hydrogen (H₂). In this work, steam reforming of n-butanol – a representative of bio-oxygenates – was studied over commercial 5% Ru/Al₂O₃ catalyst in a fixed-bed reactor. Kinetics of butanol reforming was investigated between temperatures 623 and 773 K at steam/carbon (S/C) ratio equal to 33.3 mol/mol. The W/F_A0 ratio (W: mass of catalyst, F_A0: molar flow rate of butanol in feed) was varied between 3.3 and 16.7 g h/mol. At T = 773 K, butanol conversion and H₂ yield were 93.4% and 0.61 mol/mol. Evaluation of the kinetic data showed that reaction order with respect to butanol was unity. The activation energy for the investigated reaction was 78 kJ/mol. Finally, a Langmuir-Hinshelwood model that assumed the surface reaction between the adsorbed reactants as rate-determining was used to describe the kinetic data.     

Comprehensive Modeling of Shape Memory Alloy Material Response Using a Multimechanism-Based Inelastic Model

Despite significant work over many years, using either one of the micromechanics based or phenomenological approaches, there are still prospects of much improvement to be made in constitutive modeling of shape memory alloys (SMAs). This is especially true if we sufficiently target the general scope in the modeling, i.e., including such important attributes as (1) multiaxiality; (2) possible asymmetry in tension and compression; (3) accounting for pseudoelasticity and pseudoplasticity; (4) rate dependence; and (5) effects of shape memory training under cyclic loading. The desire for comprehensive modeling of SMA materials provides the primary motivation for the inelastic model described here. Its theoretical formulation employs two main ingredients: (1) multiplicity of hardening mechanisms and (2) the partition of the energy storage/dissipation that is so vital in capturing the extremes of pseudoelasticity and pseudoplasticity in SMAs. For the purpose of validation and assessment part of the model capabilities, we report the results of a large number of simulations that were inspired by recent experimental test results under both monotonic and cyclic as well as uniaxial and multiaxial stress conditions.