On topological approach to local theory of surfaces in Calabi-Yau threefolds

We study the web of dualities relating various enumerative invariants, notably Gromov-Witten invariants and invariants that arise in topological gauge theory. In particular, we study Donaldson-Thomas gauge theory and its reductions to D=4 and D=2 which are relevant to the local theory of surfaces in Calabi-Yau threefolds.Comment: 38 pages, To Appear in Adv. Theor. Math. Phys. (2017

Crystal Engineering and Molecular Architecture

The aim of this paper is to provide a link between research projects and education to optimize teaching and learning of related subjects. In a research project, three compounds including an intermolecular proton transfer compound, a hydrated carboxylic acid, and a metallic complex were synthesized, all of them have non-covalent interactions such as O−H∙∙∙O, O−H∙∙∙N and C−H∙∙∙O hydrogen bonds as well as van der Waals forces and π-π stacking resulting to different supramolecular structures. The structures of compounds are characterized by single crystal X-ray diffraction method. The classic concepts and definitions related to the subject are given in the last section

Few Layer Reduced Graphene Oxide: Evaluation of the Best Experimental Conditions for Easy Production

This work aimed to produce graphene oxide with few graphene layers, a low number of defects, good conductivity and reasonable amount of oxygen, adequate for use as filler in polymeric composites. Two starting materials were evaluated: expanded graphite and graphite flakes. The method of oxidation used was the Staudenmaier one, which was tested over different lengths of time. No appreciable differences were found among the oxidation times and so the lowest oxidation time (24 h) was chosen as the most adequate. An investigation was also conducted into suitable temperatures for the reduction of graphite oxide. A temperature of 1000 ºC gave the best results, allowing a good quality material with few defects to be obtained. The reduction was also evaluated under inert and normal atmosphere. The best results were obtained when the least modified material, e. g., graphite flakes, was used as a starting material, oxidized for 24h and reduced at 1000 ºC for 30 s in a quartz ampoule under a normal atmosphere

Design, synthesis, and characterization of a novel Zn(II)-2-phenyl benzimidazole framework for the removal of organic dyes

Abstract A novel Zn (II) organic framework comprising 2-phenyl benzimidazole (ZPBIF-1) was synthesized by using a solvothermal method. The characterization of the synthesized MOF was performed utilizing XRD, SEM, FT-IR, 1H-NMR, 13C-NMR, MS, XPS, TG/DTA, and N2 sorption analysis. ZPBIF-1 was successfully utilized to remove Acid red 88, Basic Violet 14, Basic Blue 54, and Congo red dyes in aqueous solutions. In this study, some parameters, including adsorbent dosage, initial dye concentration, contact time, temperature, and pH, were examined. To evaluate the experimental data, Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich isotherm models were used. In this case, Langmuir is the most suitable model. Several kinetic models, including First-order, pseudo-first-order, second-order, and Pseudo-second-order kinetic models, Elovich's, and Weber's intraparticle diffusion models, were utilized to comprehend the detailed adsorption process. According to the pseudo-second-order kinetic model, dye sorption kinetics is best described. In addition, thermodynamic parameters like enthalpy (ΔH°), Gibbs free energy (ΔG°), and entropy (ΔS°) were also achieved and analyzed. The experimental studies thus suggest that Zn (II) metal–organic framework based on 2-phenyl benzimidazole could be a promising candidate for eliminating dyes from aqueous solution. Hence, the experimental studies suggest that a Zn (II) metal–organic framework based on 2-phenylbenzimidazole could be a promising candidate for eliminating dyes from aqueous solution. The maximum adsorption capacity of ZPBIF-1 was 1666.66, 1250, 1000, and 1250 mg/g for Acid red 88, Basic violet 14, Basic blue 54, and Congo red dyes, respectively. Furthermore, this method was used to remove contaminant dyes from textile wastewater, and an acceptable result was obtained

Hydrogen bond-mediated self-assembly of Tin (II) oxide wrapped with Chitosan/[BzPy]Cl network: An effective bionanocomposite for textile wastewater remediation

A novel and efficient bionanocomposite was synthesized by incorporating SnO into chitosan (Ch) and a room-temperature ionic liquid (RTIL). The bionanocomposite was synthesized in benzoyl pyridinium chloride [BzPy]Cl to maintain the unique properties of SnO, chitosan, and the ionic liquid. Adsorption and photodegradation processes were applied to evaluate the bionanocomposite for removing azo and anthraquinone dyes and textile wastewater. SnO/[BzPy]Cl and SnO/[BzPy]Cl/Ch samples were prepared and characterized using various techniques, including FT-IR, SEM, XRD, EDAX, XPS, DSC, TGA, nitrogen adsorption/desorption isotherm, and DRS analysis. SEM analysis revealed a hierarchical roughened rose flower-like morphology for the biocomposite. The band gap energies of SnO/[BzPy]Cl and SnO/[BzPy]Cl/chitosan were found to be 3.9 and 3.3 eV, respectively, indicating a reduction in the band gap energy with the introduction of [BzPy]Cl and chitosan. SnO/[BzPy]Cl/Ch showed high removal rates (92–95 %) for Fast Red, Blue 15, Red 120, Blue 94, Yellow 160, and Acid Orange 7 dyes. The adsorption kinetics followed a pseudo-second-order model.In addition, the effect of different photodegradation parameters such as solution pH, dye concentrations, contact time, and amount of photocatalyst, was studied. Given the optimal results obtained in removing azo and anthraquinone dyes, the SnO/[BzPy]Cl/Ch nanocomposite was used as an efficient nanocomposite for removing dyes from textile wastewater. The highest removal efficiency was found to be 95.8 %, obtained under ultraviolet and visible light. Furthermore, BOD and COD reduction analysis showed significant reductions, indicating the excellent performance of the photocatalyst

Characterization, crystal structure, and solution studies of a proton transfer compound obtained from 2,6-pyridinedicarboxylic acid and 1,4,10,13-tetraoxa-7,6-diazacyclooctadecane

The pro ton trans fer com pound, (DA18C6H2)(pydcH)2×0.25H2O, has been pre pared from the re ac tion be tween 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane, diaza-18-crown-6 (DA18C6), and 2,6-pyridinedicarboxylic acid, dipicolinic acid (pydcH2). The char ac ter iza tion was per formed us ing 1H and 13C NMR, IR spec tros copy and sin gle crys tal X-ray dif frac tion anal y sis. The asym met ric unit con sists of one (DA18C6H2)2+ cat ion adopt ing a sigmoidal con for ma tion which in ter acts with two (pydcH)– an ions via hy dro gen bonds in volv ing the protonated amine groups of the diazacrown ether. –COOH···–OOC– head-to-tail hy dro gen bonds gen er ate 2D un du lat - ing lay ers along [100] and [001] in the crys tal lat tice. The protonation con stants of DA18C6 and pydcH2 and equi lib rium con stants for the re ac tion of the two re ac tants were de ter mined by potentiometric pH ti tra tion. The so lu tion stud ies sup ported the for ma tion also in so lu tion of (DA18C6H2)(pydcH)2 as the most abun dant spe cies at pH = 3.4