Synthesis and characterization of a Ni nanoparticle stabilized on Ionic liquid‐functionalized magnetic Silica nanoparticles for tandem oxidative reaction of primary alcohols

In this research, preparation of the magnetic nanoparticle, coating by a silica shell using (3‐aminopropyl) triethoxysilane and synthesis of a novel sulfonic acid‐substituted imidazolium‐based ionic liquid onto the surface of these particles via a multi‐component reaction, is described. The functionalized nanoparticles was loaded by Ni nanoparticles and characterized by means of techniques such as XRD, FTIR, SEM, EDX, TEM, TGA and ICP‐OES. The nanostructures have spherical shapes that ranged in size from 80 to 100 nm. The catalytic activity of these nanoparticles was tested in aerobic oxidation of primary alcohols that showed good performance in the wide range of primary alcohols in water at mild reaction conditions. As a second step of this work, the tandem oxidative synthesis of alkylacrylonitriles and bisindolylmethanes were investigated using primary alcohols under oxidation conditions. This catalyst system can be recovered using external magnet and reused for five consecutive cycles without significantly less of its activity.     

A selective,sensitive and label-free visual assay of fructose using anti-aggregation of gold nanoparticles as a colorimetric probe

A new convenient colorimetric sensor for fructose based on anti-aggregation of citrate-capped gold nanoparticles(Au NPs) is presented. 4-Mercaptophenylboronic acid(MPBA) induces the aggregation of Au NPs, leading to a color change from red to blue. Fructose as a potent competitor has strong affinity for MPBA and a borate ester is formed between MPBA and fructose. There is an obvious color change from blue to red with increasing the concentration of fructose. The anti-aggregation effect of fructose on Au NPs was seen by the naked eye and monitored by UV–vis spectra. Our results showed that the absorbance ratio(A_(519)/A_(640)) was linear with fructose concentration in the range of 0.032–0.96 μmol/L(R~2= 0.996), with a low detection limit of 0.01 μmol/L(S/N = 3). Notably, a highly selective recognition of fructose was shown against other monosaccharide and disaccharide(glucose, mannose, galactose,lactose and saccharose). With anti-aggregation assays higher selectivity is achievable. The results of this work provide a rapid method for evaluating the quantitative analysis of fructose in human plasma at physiologically meaningful concentrations and at neutral pH. The proposed procedure can be used as an efficient method for the precise and accurate determination of fructose.     

Synthesis,structural characterization,density functional theory calculations and biological evaluation of a new organotin(IV) complex containing N‐isonicotinyl‐N',N″‐diaryl phosphorictriamide as N‐donor ligand

A new diorganotin(IV) complex with the formula SnCl₂(CH₃)₂L₂ ( C_1a ), L = 4‐NC₅H₄CONHPO(NCH₃CH₂C₆H₅)₂, was synthesized and characterized using ¹H NMR, ¹³C NMR, ³¹P NMR, ¹¹⁹Sn NMR and infrared spectroscopies. The molecular structure of C_1a was determined using X‐ray crystallography, revealing that C_1a contains hexa‐coordinated Sn(IV) centres with trans‐configuration of donor atoms around them. Each Sn(IV) atom is positioned in the centre of inversion of an octahedron. C_1a forms one‐dimensional chains via two equal intermolecular P?O…H? N hydrogen bonds. These hydrogen bonds produce centrosymmetric rings as a supramolecular hydrogen‐bonded pattern. In order to compare the relative stability of C_1a (with N‐ligated configuration) and its possible O‐ligated isomer, C_1b , density functional theory calculations were performed, the results showing a preference of C_1a over C_1b from an energy point of view. Also, natural bond orbital analysis was carried out to obtain detailed information on the electronic features of the optimized structures. The theoretical results show that intermolecular hydrogen bonding in the crystal structure has a significant role in the stabilization of C_1a , and Sn(IV) interacts more strongly with the N_py atom than the P?O functional group. Furthermore, the free ligand and its complex were tested against three human cancer cell lines, i.e. human cervical carcinoma (HeLa), human prostate cancer (PC‐3) and human breast adenocarcinoma cancer (MCF‐7). C_1a displays moderate to good cytotoxicity towards all three cancer cell lines. Moreover, antibacterial tests were carried out using the disc‐diffusion method, in which C_1a shows high activity against selected Gram‐negative and Gram‐positive bacteria. Copyright © 2015 John Wiley & Sons, Ltd.     

Design and Fabrication of Artificial Skin: Chitosan and Gelatin Immobilization on Silicone by Poly Acrylic Acid Graft Using a Plasma Surface Modification Method

Acrylic acid (AAc) was grafted onto the surfaces of polydimethylsiloxane (PDMS) films using a two-step oxygen plasma treatment. The first step of this method included oxygen plasma pretreatment of the PDMS films, immersion in AAc, and drying. The second step was carried out by plasma polymerization of the preadsorbed reactive AAc on the surfaces of the dried pretreated films. Then chitosan and gelatin were immobilized onto the poly(acrylic acid) grafted silicone through covalent bonding. The films were characterized by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and water contact angle measurements. Fibroblast cells (L929) were cultured onto the chitosan- and gelatin-immobilized poly(acrylic acid)-grafted silicone and poly(acrylic acid)-grafted silicone films. It was observed that the chitosan- and gelatin-immobilized surfaces showed significant cell growth in comparison with poly(acrylic acid)-grafted silicone samples. It seems that chitosan- and gelatin-immobilized surfaces may have an excellent potential to be used as a derm-like matrix.     

Magnetic nanoparticles grafted <Emphasis Type="SmallCaps">l</Emphasis>-carnosine dipeptide: remarkable catalytic activity in water at room temperature

Modification of magnetic nanoparticle surface with l-carnosine dipeptide was developed using a simple chemical process. In order to synthesize this catalyst system, first, magnetic nanoparticles were modified with vinyl groups using trimethoxy(vinyl)silane. Next, the vinyl groups were oxidized with H₂O₂ to give the epoxy-functionalized MNPs. Reaction of l-carnosine with epoxide rings via amino group resulted in the functionalization of MNPs surface with l-carnosine, covalently. To explore high catalytic activity of this material, l-carnosine grafted on magnetic nanoparticles (Fe₃O₄@SiO₂@LCar; l-CarMNP) was used as a highly efficient heterogeneous nano-organocatalyst in a multicomponent reaction in aqueous medium at room temperature. It was reusable at least for eight times without a significant decrease in its catalytic activity. The catalytic activity of l-CarMNP was compared with other magnetic nano-organocatalyst, and results demonstrate that l-CarMNP has high catalytic activity related to others tested.     

A quantum chemistry study on the performance of porphyrin-based solar cell sensitisers; Zinc and anchor group position effects

In this work, ten porphyrin derivatives, including free-base zinc-metalised compounds were studied by varying the position of the carboxyl anchoring group and the alkyl substituents length on the remaining three phenyl rings with the aim of the cell efficiency investigation. Theoretical performances of the sensitisers in the dye-sensitised solar cell systems have been discussed by analysis of the optical absorption, the oxidised potential of ground and excited states, light-harvesting efficiency and electron injection efficiency. Due to lower symmetry of free-based porphyrins, they showed broader bands than zinc porphyrins. The second group sensitisers are better than the first one due to the smaller oxidation potential energy, higher open-circuit voltage and light-harvesting efficiency. The influence of long alkyl substituents on the photovoltaic parameters is not perceptible but ortho and meta positions of anchoring group modify the solar cell performance. Finally, some correlations between the quantum reactivity indices and photovoltaic parameters have obtained and discussed.     

Synchronization of different-order chaotic systems: Adaptive active vs. optimal control

In this paper, an adaptive algorithm is proposed for synchronization of chaotic systems with different orders. A modular adaptive control strategy is applied to make states of the slave system track those of the master, despite the unknown parameters. One of the most advantages of the modularity approach, which is applied for the first time in chaos synchronization, is its flexibility in choosing identification and control modules and designing them completely independently. In this paper, a modified recursive least square algorithm is used to identify the unknown parameters of the slave system, and the control module is designed by means of two different algorithms. First it is designed based on active control method, and then, in order to synchronize with a lower energy, we design an optimal controller. The two methods are applied on a practical case study, and the results are compared. Two different dimensional neuron models, the HR neuron model and the cable model of cylindrical cell, are considered as the master and slave systems, respectively. Simulation results confirm the effectiveness of the proposed method.     

Minimizing total weighted late work in the resource-constrained project scheduling problem

This paper deals with resource-constrained project scheduling problem under the weighted late work criterion. Late work objective functions estimate the quality of a schedule based on durations of late parts of activities, not taking into account the amount of delay for fully late activities. It is assume that a project contains activities interrelated by finish-to-start type precedence relations with time lag of zero, which require one or more constrained renewable resources. The objective is to schedule each activity such that the total weighted late work is minimized. The problem has been formulated using a linear integer programming model and solved by the CPLEX. Also, a set of priority rules have been designed to quickly generate a set of initial solutions. In order to solve the problem optimally, a depth-first branch-and-bound algorithm is applied based on idea of minimal delaying alternatives. The branching order of nodes that belong to the same level of the search tree is determined on the basis of the developed priority rules. This results in generation six different versions of the branch-and-bound algorithm. Computational results on randomly generated problem sets are provided to analyze the efficiency of the priority rules and the branch-and-bound algorithm.