An integrated model of autonomous topological spatial cognition

This paper is focused on endowing a mobile robot with topological spatial cognition. We propose an integrated model—where the concept of a ‘place’  is defined as a collection of appearances or locations sharing common perceptual signatures or physical boundaries. In this model, as the robot navigates, places are detected in a systematic manner via monitoring coherency in the incoming visual data while pruning out uninformative or scanty data. Detected places are then either recognized or learned along with mapping as necessary. The novelties of the model are twofold: First, it explicitly incorporates a long-term spatial memory where the knowledge of learned places and their spatial relations are retained in place and map memories respectively. Second, the processing modules operate together so that the robot is able to build its spatial memory in an organized, incremental and unsupervised manner. Thus, the robot’s long-term spatial memory evolves completely on its own while learned knowledge is organized based on appearance-related similarities in a manner that is amenable for higher-level semantic reasoning, As such, the proposed model constitutes a step forward towards having robots that are capable of interacting with their environments in an autonomous manner.     

Synthesis, electrochemical and spectroelectrochemical characterization of novel soluble phthalocyanines bearing chloro and quaternizable bulky substituents on peripheral positions

A new phthalonitrile derivative (2), bearing diethylaminophenoxy - and chloro-substituents at peripheral positions was synthesized in this work. Cyclotetramerization of (2) in hexanol gave the desired metal-free (4) and metallophthalocyanines (5-8). These new phthalocyanines (4-8) were converted into water-soluble quaternized products by the reaction with methyl iodide (9-11). The novel compounds have been characterized by using elemental analysis, UV-Vis, FT-IR, ¹H NMR and MS spectroscopic data. The aggregation behaviors of the phthalocyanine complexes were studied in different solvents and concentrations. Electrochemical and spectroelectrochemical characterization of the complexes were also performed in solution. Cobalt phthalocyanine gives both metal-based and ring-based reduction processes in comparison to the complexes having 2H⁺, Zn²⁺, Ni²⁺ and Cu²⁺ metal center which give only ring-based reduction processes. Electrochemical and spectroelectrochemical measurements exhibit that all complexes oxidatively electro-polymerize on the Pt working electrode during repetitive cyclic voltammetry measurements. An in-situ electrocolorimetric method was applied to investigate the color of the electrogenerated anionic and cationic forms of the complexes for possible electrochromatic applications.     

The effects of different materials as dough improvers for organic whole wheat bread

In this research, the effects of different materials such as defatted Cephalaria syriaca flour (0.5%), rosehip (2.5%), vital gluten (2.5%) and malt flour (2%), and their combinations on the quality of organic whole wheat flour were investigated. The highest maximum resistance value was obtained in the treatment containing 0.5% cephalaria and 2.5% rosehip. The addition of malt flour and vital gluten significantly increased the extensibility value. Although rosehip, cephalaria and vital gluten generally increased the dough energy, malt flour decreased the dough energy when compared to the control. The combination of 0.5% cephalaria and 2.5% rosehip significantly decreased the adhesion and stringiness of dough. Data showed that dough rheological characteristics of organic whole wheat flour could be improved with the addition of different materials such as malt flour, cephalaria, rosehip and vital gluten.     

Synthesis and characterization of dl-thioctic acid (DLTA)-Fe3O4 nanocomposite

dl-Thioctic acid (DLTA) coated magnetite (Fe₃O₄) NP's have been prepared by the co-precipitation of iron oxide in the presence of DLTA. The product identified as magnetite, which has an average crystallite size of 7 ± 2 nm as estimated from X-ray line profile fitting. Particle size was estimated as 11 ± 1 nm from TEM micrographs. FT-IR analysis showed that the binding of DLTA on the surface of iron oxide is through carboxyl group is bidentate. VSM analysis explained the super-paramagnetic nature of the nanocomposite. TG analysis showed that the 80% of the nanocomposite was DLTA and 10% was Fe₃O₄, respectively. The conductivity measurements displayed the magnetic transition at ∼60 °C for DLTA-Fe₃O₄ NPs. Analysis of the conductivities reveals the fact that the a.c. conductivity shows a frequency-dependent behavior while d.c. electrical conductivity is strongly temperature dependent and is classified into two regions over a limited temperature range of up to 120 °C. Toxicity was tested measured by LDH assay.     

Synthesis and characteristics of poly(3-pyrrol-1-ylpropanoic acid) (PPyAA)-Fe3O4 nanocomposite

Poly(3-pyrrol-1-ylpropanoic acid) (PPyAA)-Fe₃O₄ nanocomposite was successfully synthesized by an in situ polymerization of 1-(2-carboxyethyl) pyrrole in the presence of synthesized Fe₃O₄ nanoparticles. Evaluation of structural, morphological, electrical and magnetic properties of the nanocomposite was performed by XRD, FT-IR, TEM, TGA, magnetization and conductivity measurements, respectively. XRD analysis reveals the inorganic phase as Fe₃O₄ and TGA shows about 90 wt% loading of Fe₃O₄ in the nanocomposite. FT-IR analysis indicates a successful conjugation of Fe₃O₄ particles with polypyrrole acetic acid. Magnetization measurements show that polypyrrole acetic acid coating decreases the saturation magnetization of Fe₃O₄ significantly. This reduction has been explained by the pinning of the surface spins by the possible adsorption of non-magnetic ions during the polymerization process. The conductivity and dielectric permittivity measurements strongly depend on the thermally activated polarization mechanism and thermal transition of PPyAA in the nanocomposite structure. Large value of dielectric permittivity (?′) of the nanocomposite at lower frequency is attributed to the predominance of species like Fe²⁺ ions and grain boundary defects (interfacial polarization).     

Purification and characterization of an extracellular lipase from Mucor hiemalis f. corticola isolated from soil

We have screened 39 microfungi isolates originated from soil in terms of lipolytic activity. Out of all screened, a novel strain of Mucor hiemalis f. corticola was determined to have the highest lipase activity. The extracellular lipase was produced in response to 2% glucose and 2.1% peptone. The lipase was purified 12.63-folds with a final yield of 27.7% through following purification steps; ammonium sulfate precipitation, dialysis, gel filtration column chromatography and ion exchange chromatography, respectively. MALDI-TOF MS analysis revealed 31% amino-acid identity to a known lipase from Rhizomucor miehei species. The molecular weight of the lipase was determined as 46kDa using SDS-PAGE and analytical gel filtration. Optimal pH and temperature of the lipase were determined as 7.0 and 40°C, respectively. The enzyme activity was observed to be stable at the pH range of 7.0-9.0. Thermostability assays demonstrated that the lipase was stable up to 50°C for 60min. The lipase was more stable in ethanol and methanol than other organic solvents tested. Furthermore, the activity of the lipase was slightly enhanced by SDS and PMSF. In the presence of p-NPP as substrate, K(m) and V(max) values of the lipase were calculated by Hanes-Woolf plot as 1.327mM and 91.11μmol/min, respectively.     

Synthesis and conductivity studies of piperidine-4-carboxylic acid functionalized Fe3O4 nanoparticles

Piperidine-4-carboxylic acid (PPCA) functionalized Fe₃O₄ nanoparticles as a novel organic–inorganic hybrid was fabricated and characterized by XRD, FT-IR, VSM, and TEM techniques. Its detailed electrical properties are also presented. Composition was determined as Fe₃O₄, while particles were observed to have spherical morphology. VSM measurement proved the super-paramagnetic property of the as synthesized nanocomposite. ac and dc conductivity measurements indicated semiconductor characteristics and changing trends with temperature because of reorganization of the nanocomposite. dc conductivity is strongly temperature dependent and is classified into three regions. Analysis of the real and imaginary parts of the permittivity of nanocomposite showed the ionic polarization mechanism consisting of ionic conductivity and interfacial polarization.     

Synthesis and characterization of Piperidine-4-carboxylic acid functionalized Fe3O4 nanoparticles as a magnetic catalyst for Knoevenagel reaction

Piperidine-4-carboxylic acid (PPCA) functionalized Fe₃O₄ nanoparticles as a novel organic–inorganic hybrid heterogeneous catalyst was fabricated and characterized by XRD, FT-IR, TGA, TEM and VSM techniques. Composition was determined as Fe₃O₄, while particles were observed to have spherical morphology. Size estimations using X-ray line profile fitting (10 nm), TEM (11 nm) and magnetization fitting (9 nm) agree well, revealing nearly single crystalline character of Fe₃O₄ nanoparticles. Magnetization measurements reveal that PPCA functionalized Fe₃O₄ NPs have superparamagnetic features, namely immeasurable coercivity and absence of saturation. Small coercivity is established at low temperatures. The catalytic activity of Fe₃O₄–PPCA was probed through one-pot synthesis of nitro alkenes through Knoevenagel reaction in CH₂Cl₂ at room temperature. The heterogeneous catalyst showed very high conversion rates (97%) and could be recovered easily and reused many times without significant loss of its catalytic activity.     

Hydrothermal Synthesis and Characterization of PEG-Mn3O4 Nanocomposite

Nano-Micro Letters - Here, we report on the synthesis of PEG-Mn3O4 nanocomposite (NP’s) via a hydrothermal route by using Mn(acac)2, ethanol, NH3 and PEG-400. The crystalline phase was...