Tb3+ sensitization in a deoxycholate organogel matrix, and selective quenching of luminescence by an aromatic nitro derivative

In this article, we present the discovery of a metallo-organogel derived from a Tb3+ salt and sodium deoxycholate (NaDCh) in methanol. The gel was made luminescent through sensitization of Tb3+ by doping with 2,3-dihydroxynaphthalene (DHN) in micromolar concentrations. Rheological measurements of the mechanical properties of the organogel confirmed the characteristics of a true gel. Significant quenching of Tb3+ luminescence was observed in the deoxycholate gel matrix by 2,4,7-trinitrofluorenone (TNF), but not by several other polynitro aromatics. Microscopic studies (AFM, TEM and SEM) revealed a highly entangled fibrous network. The xerogels retained luminescent properties suggesting the possibility for application in coatings, etc.

Cooperative Particle Swarm Optimization Based Receiver for Large-Dimension MIMO-ZPSC Systems

In this paper, we propose a cooperative particle swarm optimization (CPSO) based channel estimation/equalization scheme for multiple-input multiple-output zero-padded single-carrier (MIMO-ZPSC) systems with large dimensions in frequency selective channels. We estimate the channel state information at the receiver in time domain using a PSO based algorithm during training phase. Using the estimated channel, we perform information symbol detection in the frequency domain using FFT based processing. For this detection, we use a low complexity OLA (OverLap Add) likelihood ascent search equalizer which uses minimum mean square (MMSE) equalizer solution as the initial solution. Multiple iterations between channel estimation and data detection are carried out which significantly improves the mean square error and bit error rate performance of the receiver.

Communication: Benzene dimer-The free energy landscape

Establishing the relative orientation of the two benzene molecules in the dimer has remained an enigmatic challenge. Consensus has narrowed the choice of structures to either a T-shape, that may be tilted, or a parallel displaced arrangement, but the relatively small energy differences makes identifying the global minimum difficult. Here we report an ab initio Car-Parrinello Molecular Dynamics based metadynamics computation of the free-energy landscape of the benzene dimer. Our calculations show that although competing structures may be isoenergetic, free energy always favors a tilted T-shape geometry at all temperatures where the bound benzene dimer exist. (C) 2013 AIP Publishing LLC.

Role of melt convection on optimization of PCM-based heat sink under cyclic heat load

In this article, we study the thermal performance of phase-change material (PCM)-based heat sinks under cyclic heat load and subjected to melt convection. Plate fin type heat sinks made of aluminum and filled with PCM are considered in this study. The heat sink is heated from the bottom. For a prescribed value of heat flux, design of such a heat sink can be optimized with respect to its geometry, with the objective of minimizing the temperature rise during heating and ensuring complete solidification of PCM at the end of the cooling period for a given cycle. For given length and base plate thickness of a heat sink, a genetic algorithm (GA)-based optimization is carried out with respect to geometrical variables such as fin thickness, fin height, and the number of fins. The thermal performance of the heat sink for a given set of parameters is evaluated using an enthalpy-based heat transfer model, which provides the necessary data for the optimization algorithm. The effect of melt convection is studied by taking two cases, one without melt convection (conduction regime) and the other with convection. The results show that melt convection alters the results of geometrical optimization.

Cross-Hetero-Dehydrogenative Coupling Reaction of Phosphites: A Catalytic Metal-Free Phosphorylation of Amines and Alcohols

Phosphorylation of amines, alcohols, and sulfoximines are accomplished using molecular iodine as a catalyst and H2O2 as the sole oxidant under mild reaction conditions. This method provides an easy route for synthesizing a variety of phosphoramidates, phosphorus triesters and sulfoximine-derived phosphoramidates which are of biological importance.

Gibbs free energy of formation of rhodium sulfides

Using a solid-state electrochemical technique, thermodynamic properties of three sulfide phases (RhS0.882, Rh3S4, Rh2S3) in the binary system (Rh + S) are measured as a function of temperature over the range from (925 to 1275) K. Single crystal CaF2 is used as the electrolyte. The auxiliary electrode consisting of (CaS + CaF2) is designed in such a way that the sulfur chemical potential converts into an equivalent fluorine potential at each electrode. The sulfur potentials at the measuring electrodes are established by the mixtures of (Rh + RhS0.882), (RhS0.882 + Rh3S4) and (Rh3S4 + Rh2S3) respectively. A gas mixture (H-2 + H2S + Ar) of known composition fixes the sulfur potential at the reference electrode. A novel cell design with physical separation of rhodium sulfides in the measuring electrode from CaS in the auxiliary electrode is used to prevent interaction between the two sulfide phases. They equilibrate only via the gas phase in a hermetically sealed reference enclosure. Standard Gibbs energy changes for the following reactions are calculated from the electromotive force of three cells: 2.2667Rh (s) + S-2 (g) -> 2.2667RhS(0.882) (s), Delta(r)G degrees +/- 2330/(J . mol(-1)) = -288690 + 146.18 (T/K), 4.44RhS(0.882) (s) + S-2 (g) -> 1.48Rh(3)S(4) (s), Delta(r)G degrees +/- 2245/(J . mol(-1)) = -245596 + 164.31 (T/K), 4Rh(3)S(4) (s) + S-2 (g) -> 6Rh(2)S(3) (s), Delta(r)G degrees +/- 2490/(J . mol(-1)) = -230957 + 160: 03 (T/K). Standard entropy and enthalpy of formation of rhodium sulfides from elements in their normal standard states at T = 298.15 K are evaluated. (C) 2013 Elsevier Ltd. All rights reserved.

Long ranged structural modulation in the pre-morphotropic phase boundary cubic-like state of the lead-free piezoelectric Na1/2Bi1/2TiO3-BaTiO3

The nature of the pre-morphotropic phase boundary (MPB) cubic-like state in the lead-free piezoelectric ceramics (1-x)Na1/2Bi1/2TiO3-(x)BaTiO3 at x similar to 0.06 has been examined in detail by electric field and temperature dependent neutron diffraction, x-ray diffraction, dielectric and ferroelectric characterization. The superlattice reflections in the neutron diffraction patterns cannot be explained with the tetragonal P4bm and the rhombohedral (R3c) phase coexistence model. The cubic like state is rather a result of long ranged modulated complex octahedral tilt. This modulated structure exhibits anomalously large dielectric dispersion. The modulated structure transforms to a MPB state on poling. The field-stabilized MPB state is destroyed and the modulated structure is restored on heating the poled specimen above the Vogel-Fulcher freezing temperature. The results show the predominant role of competing octahedral tilts in determining the nature of structural and polar states in Na1/2Bi1/2TiO3-based ferroelectrics. (C) 2013 AIP Publishing LLC.

Flexibility in Food Extraction Techniques in Urban Free-Ranging Bonnet Macaques, Macaca radiata

Non-human primate populations, other than responding appropriately to naturally occurring challenges, also need to cope with anthropogenic factors such as environmental pollution, resource depletion, and habitat destruction. Populations and individuals are likely to show considerable variations in food extraction abilities, with some populations and individuals more efficient than others at exploiting a set of resources. In this study, we examined among urban free-ranging bonnet macaques, Macaca radiata (a) local differences in food extraction abilities, (b) between-individual variation and within-individual consistency in problem-solving success and the underlying problem-solving characteristics, and (c) behavioral patterns associated with higher efficiency in food extraction. When presented with novel food extraction tasks, the urban macaques having more frequent exposure to novel physical objects in their surroundings, extracted food material from PET bottles and also solved another food extraction task (i.e., extracting an orange from a wire mesh box), more often than those living under more natural conditions. Adults solved the tasks more frequently than juveniles, and females more frequently than males. Both solution-technique and problem-solving characteristics varied across individuals but remained consistent within each individual across the successive presentations of PET bottles. The macaques that solved the tasks showed lesser within-individual variation in their food extraction behavior as compared to those that failed to solve the tasks. A few macaques appropriately modified their problem-solving behavior in accordance with the task requirements and solved the modified versions of the tasks without trial-and-error learning. These observations are ecologically relevant - they demonstrate considerable local differences in food extraction abilities, between-individual variation and within-individual consistency in food extraction techniques among free-ranging bonnet macaques, possibly affecting the species' local adaptability and resilience to environmental changes.

Endocrine Correlates of Musth in Free-Ranging Asian Elephants (Elephas maximus) Determined by Non-Invasive Faecal Steroid Hormone Metabolite Measurements

The occurrence of musth, a period of elevated levels of androgens and heightened sexual activity, has been well documented for the male Asian elephant (Elephas maximus). However, the relationship between androgen-dependent musth and adrenocortical function in this species is unclear. The current study is the first assessment of testicular and adrenocortical function in free-ranging male Asian elephants by measuring levels of testosterone (androgen) and cortisol (glucocorticoid - a physiological indicator of stress) metabolites in faeces. During musth, males expectedly showed significant elevation in faecal testosterone metabolite levels. Interestingly, glucocorticoid metabolite concentrations remained unchanged between musth and non-musth periods. This observation is contrary to that observed with wild and captive African elephant bulls and captive Asian bull elephants. Our results show that musth may not necessarily represent a stressful condition in free-ranging male Asian elephants.

Numerical and experimental investigation and optimization of an open wheeled race car cooling air duct

In this study the cooling performance due to air flow and aerodynamics of the Formula Student open wheeled race car has been investigated and optimized with the help of CFD simulations and experimental validation. The race car in context previously suffered from overheating problems. Flow analysis was carried out based on the detailed race car 3D model (NITK Racing 2012 formula student race car). Wind tunnel experiments were carried out on the same. The results obtained from the computer simulations are compared with experimental results obtained from wind tunnel testing of the full car. Through this study it was possible to locate the problem areas and hence choose the best configuration for the cooling duct. The CFD analysis helped in calculating the mass flow rate, pressure and velocity distribution for different velocities of the car which is then used to determine the heat dissipated by the radiator. Area of flow separation could be visualized and made sure smooth airflow into the radiator core area. This significantly increased the cooling performance of the car with reduction in drag.

Optimization of rheological properties of photopolymerizable alumina suspensions for ceramic microstereolithography

Microstereolithography (MSL) is a rapid prototyping technique to fabricate complex three-dimensional (3D) structure in the microdomain involving different materials such as polymers and ceramics. The present effort is to fabricate microdimensional ceramics by the MSL system from a non-aqueous colloidal slurry of alumina. This slurry predominantly consists of two phases i.e. sub-micrometer solid alumina particles and non-aqueous reactive difunctional and trifunctional acrylates with inert diluent. The first part of the work involves the study of the stability and viscosity of the slurry using different concentrations of trioctyl phosphine oxide (TOPO) as a dispersant. Based on the optimization, the highest achievable solid loadings of alumina has been determined for this particular colloidal suspension. The second part of the study highlights the fabrication of several micro-dimensional alumina structures by the MSL system. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Synthesis, structural studies and catalytic activity of dioxidomolybdenum(VI) complexes with aroylhydrazones of naphthol-derivative

Reaction of the salicylhydrazone of 2-hydroxy-1-naphthaldehyde (H2L1), anthranylhydrazone of 2hydroxy-l-naphthaldehyde (H2L2), benzoylhydrazone of 2-hydroxy-1-acetonaphthone (H2L3) and anthranylhydrazone of 2-hydroxy-1-acetonaphthone (H2L4; general abbreviation H2L) with MoO2(acac)21 afforded a series of 5- and 6- coordinate Mo(VI) complexes of the type MoO2L1-2(ROH)] where R = C2H5 (1) and CH3 (2)], and MoO2L3-4] (3 and 4). The substrate binding capacity of 1 has been demonstrated by the formation of one mononuclear mixed-ligand dioxidomolybdenum complex MoO2L1(Q)] (where Q= gamma-picoline (la)). Molecular structure of all the complexes (I, la, 2,3 and 4) is determined by X-ray crystallography, demonstrating the dibasic tridentate behavior of ligands. All the complexes show two irreversible reductive responses within the potential window -0.73 to -1.08 V, due to Movl/Mov and Mov/Mow processes. Catalytic potential of these complexes was tested for the oxidation of benzoin using 30% aqueous H2O2 as an oxidant in methanol. At least four reaction products, benzoic acid, benzaldehydedimethylacetal, methyl benzoate and benzil were obtained with the 95-99% conversion under optimized reaction conditions. Oxidative bromination of salicylaldehyde, a functional mimic of haloperoxidases, in aqueous 1-1202/KEr in the presence of HC1O4 at room temperature has also been carried out successfully. (C) 2013 Elsevier Ltd. All rights reserved.

Optimum steering input determination and path-tracking of all-wheel steer vehicles on uneven terrains based on constrained optimization

In this paper we propose a framework for optimum steering input determination of all-wheel steer vehicles (AWSV) on rough terrains. The framework computes the steering input which minimizes the tracking error for a given trajectory. Unlike previous methodologies of computing steering inputs of car-like vehicles, the proposed methodology depends explicitly on the vehicle dynamics and can be extended to vehicle having arbitrary number of steering inputs. A fully generic framework has been used to derive the vehicle dynamics and a non-linear programming based constrained optimization approach has been used to compute the steering input considering the instantaneous vehicle dynamics, no-slip and contact constraints of the vehicle. All Wheel steer Vehicles have a special parallel steering ability where the instantaneous centre of rotation (ICR) is at infinity. The proposed framework automatically enables the vehicle to choose between parallel steer and normal operation depending on the error with respect to the desired trajectory. The efficacy of the proposed framework is proved by extensive uneven terrain simulations, for trajectories with continuous or discontinuous velocity profile.

Modified roaming optimization for multi-modal optima

This paper explains the algorithm of Modified Roaming Optimization (MRO) for capturing the multiple optima for multimodal functions. There are some similarities between the Roaming Optimization (RO) and MRO algorithms, but the MRO algorithm is created to overcome the problems facing while applying the RO to the problems possessing large number of solutions. The MRO mainly uses the concept of density to overcome the challenges posed by RO. The algorithm is tested with standard test functions and also discussions are made to improve the efficacy of the MRO algorithm. This paper also gives the results of MRO applied for solving Inverse Kinematics (IK) problem for SCARA and PUMA robots.

Template-free multicomponent coordination-driven self-assembly of Pd(II)/Pt(II) molecular cages

Recent years have seen a tremendous increase in the interest for constructing hollowed-out molecular frameworks, for their potential uses. Metal-ligand coordination-driven self-assembly has provided multitudes of opportunities in the formation of molecular architectures of desired shapes and sizes, with the help of the information already coded in the components. This article summarizes the recent developments in the construction of multicomponent molecular cages through this process, with a focus on the decreasing relevance of templates, and use of these systems in catalysis/host-guest chemistry.