Journal of Chemistry https://www.hindawi.com The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Effects of Neutralization, Decoloration, and Deodorization on Polycyclic Aromatic Hydrocarbons during Laboratory-Scale Oil Refining Process Sun, 28 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/7824761/ The influence of technological operations during oil refining process on polycyclic aromatic hydrocarbons (PAHs) in neutralized, bleached, and deodorized oils was investigated on the basis of laboratory-scale study. Under the best experimental conditions, benzo[a]pyrene decreased by 85.1%, 99.7%, and 40.8% in neutralized, bleached, and deodorized oils, respectively. Total of 16 analytes decreased by 55.7%, 87.5%, and 47.7%, respectively. Bleaching with activated charcoal was the most efficient procedure to reduce PAHs in crude oil. Neutralization had a modest influence on sixteen analytes; however, deodorization was only responsible for a slight decrease in the light PAHs and heavy PAHs contents. Data obtained in this study suggest that the use of activated carbon during oil refining process is highly recommended; moreover, these results provide a useful guidance for oil refining plant to reduce security risk and ensure the quality of the vegetable oil products. Yuxiang Ma, Longkai Shi, Yulan Liu, and Qiyu Lu Copyright © 2017 Yuxiang Ma et al. All rights reserved. Vibrational Spectroscopies and Chemometry for Nondestructive Identification and Differentiation of Painting Binders Thu, 25 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/3475659/ A comprehensive dataset of vibrational spectra of different natural organic binding media is presented and discussed. The binding media were applied on a glass substrate and analyzed after three months of natural ageing. The combination of Raman and FT-NIR spectroscopies allows for an improved identification of these materials as Raman technique is more informative about the skeletal vibrations, while FT-NIR spectroscopy is more sensitive to the substituents and polar groups. The experimental results are initially discussed in the framework of current spectral assignment. Then, multivariate analysis (PCA) is applied leading to differentiation among the samples. The two major principal components allow for a complete separation of the different classes of organic materials. Further differentiation within the same class is possible thanks to the secondary components. The loadings obtained from PCA are discussed on the basis of the spectral assignment leading to clear understanding of the physical basis of this differentiation process. Serena Carlesi, Maurizio Becucci, and Marilena Ricci Copyright © 2017 Serena Carlesi et al. All rights reserved. A Quantum-Chemical DFT Approach to Elucidation of the Chirality Transfer Mechanism of the Enantioselective Suzuki–Miyaura Cross-Coupling Reaction Thu, 25 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/3617527/ The DFT calculations of the simplified model of the asymmetric Suzuki–Miyaura coupling reaction were performed at the M062x/LANL2DZ theory level at first. It was found that enantioselective reactions mediated by the palladium complexes of chiral C,P-ligands follow a four-stage mechanism similar to that proposed previously as one of the most credible mechanisms. It should be underlined that the presence of substituents in the substrates and the chiral ligand at ortho positions determines the energies of possible diastereoisomeric transition states and intermediates in initial reaction steps. This suggests that, in practice, a sharp selection of theoretically possible paths of chirality transfer from the catalyst to the product should have a place and, therefore, the absolute configuration of the formed atropisomeric product is defined and can be predicted. Radomir Jasiński, Oleg M. Demchuk, and Dmytro Babyuk Copyright © 2017 Radomir Jasiński et al. All rights reserved. Synthesis, Characterization, and Tautomerism of 1,3-Dimethyl Pyrimidine-2,4,6-Trione s-Triazinyl Hydrazine/Hydrazone Derivatives Wed, 24 May 2017 06:48:27 +0000 http://www.hindawi.com/journals/jchem/2017/5702962/ 1,3,5-Triazines and pyrimidine-2,4,6-triones belong to that class of compounds which are well known in literature for possessing wide range of biological activities. Here, we report a new family of compounds that encompasses these two structures. The union of both heterocycles was carried out through a hydrazone moiety incorporated into an acetyl group at the position 5 of 1,3-dimethyl pyrimidine derivative. The synthetic strategy adopted allowed the preparation of the target compounds with excellent yields and good purities. The synthesized compounds were well characterized by NMR (1H and 13C), HRMS, and elemental analysis. Furthermore, the tautomerism of enhydrazine versus hydrazone has also been studied. Anamika Sharma, Yahya Jad, Mohammed R. H. Siddiqui, Beatriz G. de la Torre, Fernando Albericio, and Ayman El-Faham Copyright © 2017 Anamika Sharma et al. All rights reserved. Preparation and Optimization of 10-Hydroxycamptothecin Nanocolloidal Particles Using Antisolvent Method Combined with High Pressure Homogenization Wed, 24 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/5752090/ The aim of this study was to prepare 10-hydroxycamptothecin nanocolloidal particles (HCPTNPs) to increase the solubility of drugs, reduce the toxicity, improve the stability of the drug, and so forth. HCPTNPs was prepared by antisolvent precipitation (AP) method combined with high pressure homogenization (HPH), followed by lyophilization. The main parameters during antisolvent process including volume ratio of dimethyl sulfoxide (DMSO) and H2O and dripping speed were optimized and their effects on mean particle size (MPS) and yield of HCPT primary particles were investigated. In the high pressure homogeneous procedure, types of surfactants, amount of surfactants, and homogenization pressure (HP) were optimized and their influences on MPS, zeta potential (ZP), and morphology were analyzed. The optimum conditions of HCPTNPs were as follows: 0.2 mg/mL HCPT aqueous suspension, 1% of ASS, 1000 bar of HP, and 20 passes. Finally, the HCPTNPs via lyophilization using glucose as lyoprotectant under optimum conditions had an MPS of 179.6 nm and a ZP of 28.79 ± 1.97 mV. The short-term stability of HCPTNPs indicated that the MPS changed in a small range. Bolin Lian, Yong Li, Xiuhua Zhao, Yuangang Zu, Ying Wang, Yin Zhang, and Yuanyuan Li Copyright © 2017 Bolin Lian et al. All rights reserved. A New Approach for Accurate Prediction of Liquid Loading of Directional Gas Wells in Transition Flow or Turbulent Flow Tue, 23 May 2017 07:03:33 +0000 http://www.hindawi.com/journals/jchem/2017/4969765/ Current common models for calculating continuous liquid-carrying critical gas velocity are established based on vertical wells and laminar flow without considering the influence of deviation angle and Reynolds number on liquid-carrying. With the increase of the directional well in transition flow or turbulent flow, the current common models cannot accurately predict the critical gas velocity of these wells. So we built a new model to predict continuous liquid-carrying critical gas velocity for directional well in transition flow or turbulent flow. It is shown from sensitivity analysis that the correction coefficient is mainly influenced by Reynolds number and deviation angle. With the increase of Reynolds number, the critical liquid-carrying gas velocity increases first and then decreases. And with the increase of deviation angle, the critical liquid-carrying gas velocity gradually decreases. It is indicated from the case calculation analysis that the calculation error of this new model is less than 10%, where accuracy is much higher than those of current common models. It is demonstrated that the continuous liquid-carrying critical gas velocity of directional well in transition flow or turbulent flow can be predicted accurately by using this new model. Ruiqing Ming and Huiqun He Copyright © 2017 Ruiqing Ming and Huiqun He. All rights reserved. Molecular Dynamics Study of the Factors Influencing the β-Cyclodextrin Inclusion Complex Formation of the Isomers of Linear Molecules Mon, 22 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/6907421/ The influence of the size, composition, and atomic distribution of linear guests on -cyclodextrin inclusion complex formation is clarified by means of a molecular dynamics simulation at constant temperature. The intermolecular energy is modelled by a Lennard-Jones potential, where the molecular composition is represented by various parameters and by a continuum description of the guest and cavity walls. It is concluded that the parameters related to the atomic size require minimum values for the confinement of linear molecules inside the cavity. The isomer with optimal affinity for -cyclodextrin as predicted by the free energy presents an asymmetrical molecular structure, and the position probability density shows that the isomer tends to insert the portion with largest atoms into the cavity, although the preferential binding site of the guest is not always located in regions of the host with maximum discriminatory power. E. Alvira Copyright © 2017 E. Alvira. All rights reserved. Green Synthesis and Characterization of Biosilica Produced from Sugarcane Waste Ash Sun, 21 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/6129035/ In this study, ash from sugarcane waste was used in the synthesis of biosilica using alkaline extraction followed by acid precipitation. Different parameters that could influence the silica particle synthesis were evaluated. The ash and synthesized biosilica were characterized by a combination of spectroscopic and chemical techniques such as XRD, XRF, SEM, particle size analyser, N2 adsorption analysis, TGA, and FTIR. The best condition for biosilica production was achieved with fusion method and aging temperature of 80°C for 1 h during gel formation. X-ray powder diffraction pattern confirms the amorphous nature of synthesized silica. The purity of the prepared silica was 99% silica which was confirmed by means of XRF. The experimental data suggest that the sugarcane waste ash could be converted into a value-added product, minimizing the environmental impact of disposal problems. Rodrigo Heleno Alves, Thais Vitória da Silva Reis, Suzimara Rovani, and Denise Alves Fungaro Copyright © 2017 Rodrigo Heleno Alves et al. All rights reserved. Fatty Amides from Crude Rice Bran Oil as Green Corrosion Inhibitors Thu, 18 May 2017 08:59:06 +0000 http://www.hindawi.com/journals/jchem/2017/2871034/ Due to its high oil content, this research proposes the use of an agroindustrial byproduct (rice bran) as a sustainable option for the synthesis of corrosion inhibitors. From the crude rice bran oil, the synthesis of fatty amide-type corrosion inhibitors was carried out. The corrosion inhibitory capacity of the fatty amides was evaluated on an API X-70 steel using electrochemical techniques such as real-time corrosion monitoring and potentiodynamic polarization curves. As a corrosive medium, a CO2-saturated solution (3.5% NaCl) was used at three temperatures (30, 50, and 70°C) and different concentrations of inhibitor (0, 5, 10, 25, 50, and 100 ppm). The results demonstrate that the sustainable use of agroindustrial byproducts is a good alternative to the synthesis of environmentally friendly inhibitors with high corrosion inhibition efficiencies. E. Reyes-Dorantes, J. Zuñiga-Díaz, A. Quinto-Hernandez, J. Porcayo-Calderon, J. G. Gonzalez-Rodriguez, and L. Martinez-Gomez Copyright © 2017 E. Reyes-Dorantes et al. All rights reserved. Bioactive Phytochemicals: Efficient Synthesis of Optically Active Substituted Flav-3-enes and Flav-3-en-3-o-R Derivatives Thu, 18 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/3971253/ The structural core of flavene (2-phenyl-2H-chromene) is commonly found in plant flavonoids, which exhibit a wide range of biological activities and diverse pharmacological profiles (e.g., antioxidant and anticancer activities). Flavonoids have attracted significant interest in medicinal and synthetic chemistry. Substituted flav-3-ene 13 was exclusively synthesized by the stereoselective elimination of the O-mesyl moiety on C-3 of 5,7,3′,4′-tetramethoxyflavan-3-mesylate 12 with 1,8-diazabicyclo[5.4.0]undec-7-ene. The reaction of 5,7,3′,4′-tetramethoxyflavan-3-one 15 with ytterbium trifluoromethanesulfonate in methanol afforded a novel 3-O-substituted flav-3-ene derivative (3,5,7,3′,4′-pentamethoxyflav-3-ene) 17. The reduction of 4-(1,3,5-trihydroxybenzene)-5,7,3′,4′-tetra-O-benzylflavan-3-one 19b with hydrogen afforded a new compound: 3-hydroxy-4-(1,3,5-trihydroxybenzene)-5,7,3′,4′-tetrahydroxyflavan-3-en-3-ol 21 in good yield (95%), while the acetylation of 19a and 21 afforded the expected novel flav-3-en-3-acetoxy derivatives 20 (92%) and 22 (90%), respectively. Matthew Chilaka Achilonu, Moosa Mahmood Sedibe, and Karabo Shale Copyright © 2017 Matthew Chilaka Achilonu et al. All rights reserved. On the Interactions of Fused Pyrazole Derivative with Selected Amino Acids: DFT Calculations Sun, 14 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/8124323/ Due to the increasing prevalence of neoplasms, there is a permanent need for new selective cytostatic compounds. Anticancer drugs can act in different ways, affecting protein expression and synthesis, including disruption of signaling pathways within cells. Continuing our previous research aiming at elucidating the mechanism of pyrazole’s anticancer activity, we carried out in silico studies on the interactions of fused pyrazole derivative with alanine, lysine, glutamic acid, and methionine. The objective of the study is to improve our understanding of the possible interactions of pyrazole derivatives with the above-mentioned amino acids. For this purpose, we apply the DFT formalism (optimization using the B3LYP, CAM-B3LYP, PBE0, and M06L functionals) and interaction energy calculations (counterpoise corrected method based on the basis set superposition error, BSSE) together with QTAIM approach and estimation of the 1H NMR chemical shifts of analyzed pyrazole derivative using different basis sets and DFT functionals in CPCM solvation model (and water used as a solvent). Kornelia Czaja, Jacek Kujawski, Elżbieta Jodłowska-Siewert, Paulina Szulc, Tomasz Ratajczak, Dominika Krygier, Marcin K. Chmielewski, and Marek K. Bernard Copyright © 2017 Kornelia Czaja et al. All rights reserved. Equilibrium Measurements of the NH3-CO2-H2O System: Speciation Based on Raman Spectroscopy and Multivariate Modeling Thu, 11 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/7590506/ Liquid speciation is important for reliable process design and optimization of gas-liquid absorption process. Liquid-phase speciation methods are currently available, although they involve tedious and time-consuming laboratory work. Raman spectroscopy is well suited for in situ monitoring of aqueous chemical reactions. Here, we report on the development of a method for speciation of the CO2-NH3-H2O equilibrium using Raman spectroscopy and PLS-R modeling. The quantification methodology presented here offers a novel approach to provide rapid and reliable predictions of the carbon distribution of the CO2-NH3-H2O system, which may be used for process control and optimization. Validation of the reported speciation method which is based on independent, known, NH3-CO2-H2O solutions shows estimated prediction uncertainties for carbonate, bicarbonate, and carbamate of 6.45 mmol/kg H2O, 34.39 mmol/kg H2O, and 100.9 mmol/kg H2O, respectively. Maths Halstensen, Henrik Jilvero, Wathsala N. Jinadasa, and Klaus-J. Jens Copyright © 2017 Maths Halstensen et al. All rights reserved. Extraction and Physicochemical Characterization of Mucilage from Opuntia cochenillifera (L.) Miller Wed, 10 May 2017 07:50:03 +0000 http://www.hindawi.com/journals/jchem/2017/4301901/ The aim of this study was to extract mucilage from O. cochenillifera (L.) cacti and determine its functional and physicochemical properties. The best mucilage yield (31%) was obtained by nonthermal extraction with hydration. The mucilage has appreciable carbohydrate and protein contents. The phytochemical analysis shown the presence of alkaloids and terpenes/steroids. The Fourier transformed infrared (FT-IR) spectrum of the mucilage exhibits typical bands for carbohydrates as O–H, C–H, and –COO−. The mucilage demonstrated water- and oil-holding capacities of 2.78 g water/g dry mucilage and 1.80 g oil/g dry mucilage, respectively, these properties can have a positive effect on the texture of the products when used as a stabilizer. The mildly acidic pH (4.8–5) contributes to its emulsifying capacity. The presence of electrolytes in the mucilage can be of great value in flocculation processes. The mucilage forms low viscosity solutions in the same manner as gum Arabic. Finally, its potential for use as a textile dye remover was evaluated, achieving a 70% removal rate from aqueous solutions. The prepared mucilage exhibits properties that recommend it as a natural material that can be used as an additive in the chemical, food, pharmaceuticals and cosmetics industries, as well as in decontamination processes. Mariel Monrroy, Erick García, Katherine Ríos, and José Renán García Copyright © 2017 Mariel Monrroy et al. All rights reserved. Characterization of Recharge Mechanisms and Sources of Groundwater Salinization in Ras Jbel Coastal Aquifer (Northeast Tunisia) Using Hydrogeochemical Tools, Environmental Isotopes, GIS, and Statistics Mon, 08 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/8610894/ Groundwater is among the most available water resources in Tunisia; it is a vital natural resource in arid and semiarid regions. Located in north-eastern Tunisia, the Metline-Ras Jbel-Raf Raf aquifer is a mio-plio-quaternary shallow coastal aquifer, where groundwater is the most important source of water supply. The major ion hydrochemistry and environmental isotope composition (δ18O, δ2H) were investigated to identify the recharge sources and processes that affect the groundwater salinization. The combination of hydrogeochemical, isotopic, statistical, and GIS approaches demonstrates that the salinity and the groundwater composition are largely controlled by the water-rock interaction particularly the dissolution of evaporate minerals and the ion exchange process, the return flow of the irrigation water, agricultural fertilizers, and finally saltwater intrusion which started before 1980 and which is partially mitigated by the artificial recharge since 1993. As for the stable isotope signatures, results showed that groundwater samples lay on and around the local meteoric water line LMWL; hence, this arrangement signifies that the recharge of the Ras Jbel aquifer is ensured by recent recharge from Mediterranean air masses. Jamila Hammami Abidi, Boutheina Farhat, Abdallah Ben Mammou, and Naceur Oueslati Copyright © 2017 Jamila Hammami Abidi et al. All rights reserved. Synthesis of Iron Doped Zeolite Imidazolate Framework-8 and Its Remazol Deep Black RGB Dye Adsorption Ability Thu, 04 May 2017 09:07:38 +0000 http://www.hindawi.com/journals/jchem/2017/5045973/ Zeolite imidazole framework-8 (ZIF-8) and the iron doped ZIF-8 (Fe-ZIF-8) were synthesized by the hydrothermal process. The obtained materials were characteristic of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), nitrogen adsorption/desorption isotherms, and atomic absorption spectroscopy (AAS). The results showed that the obtained Fe-ZIF-8 possessed the ZIF-8 structure with a large specific area. ZIF-8 and Fe-ZIF-8 were used for the removal of Remazol Deep Black (RDB) RGB dye from aqueous solutions. The various factors affecting adsorption such as pH, initial concentration, contact time, and temperature were investigated. The results showed that the introduction of iron into ZIF-8 provided a much larger adsorption capacity and faster adsorption kinetics than ZIF-8 without iron. The electrostatic interaction and π-π interaction between the aromatic rings of the RDB dye and the aromatic imidazolate rings of the adsorbent were responsible for the RDB adsorption. Moreover, the coordination of the nitrogen atoms and oxygen in carboxyl group in RDB molecules with the Fe2+ ions in the ZIF-8 framework played a vital role for the effective removal of RDB from aqueous solution. Mai Thi Thanh, Tran Vinh Thien, Vo Thi Thanh Chau, Pham Dinh Du, Nguyen Phi Hung, and Dinh Quang Khieu Copyright © 2017 Mai Thi Thanh et al. All rights reserved. New Caffeic Acid Phenylethyl Ester Analogs Bearing Substituted Triazole: Synthesis and Structure-Activity Relationship Study towards 5-Lipoxygenase Inhibition Thu, 04 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/2380531/ Leukotrienes are biosynthesized by the conversion of arachidonic acid by 5-Lipoxygenase and play a key role in many inflammatory disorders. Inspired by caffeic acid phenylethyl ester (CAPE) (2) and an analog carrying a triazole substituted by cinnamoyl and 5-LO inhibitors recently reported by our team, sixteen new CAPE analogs bearing substituted triazole were synthesized by copper catalyzed Huisgen 1,3-dipolar cycloaddition. Compound 10e, an analog bearing p-CF3 phenethyl substituted triazole, was equivalent to CAPE (2) but clearly surpassed Zileuton (2), the only approved 5-LO inhibitor. Substitution of the phenethyl moiety by cyclohexylethyl, as with 12g, clearly increased 5-LO inhibition which confirms the importance of hydrophobic interactions. Molecular docking revealed new hydrogen bonds and π-π interactions between the enzyme and some of the investigated compounds. Overall, this work highlights the relevance of exploring polyphenolic compounds as leukotrienes biosynthesis inhibitors. Pierre-Philipe Roy, Diene Faye, Sébastien Blanchard, Marc Cormier, Jérémie A. Doiron, Marc E. Surette, and Mohamed Touaibia Copyright © 2017 Pierre-Philipe Roy et al. All rights reserved. Chemical Characterization of Major and Minor Compounds of Nut Oils: Almond, Hazelnut, and Pecan Nut Tue, 02 May 2017 08:14:12 +0000 http://www.hindawi.com/journals/jchem/2017/2609549/ The aim of this work was to characterize the major and minor compounds of laboratory-extracted and commercial oils from sweet almond, hazelnut, and pecan nut. Oils from sweet almond, hazelnut, and pecan nut were obtained by means of an expeller system, while the corresponding commercial oils were provided from Vital Âtman (BR). The contents of triacylglycerols, fatty acids, aliphatic and terpenic alcohols, desmethyl-, methyl-, and dimethylsterols, squalene, and tocopherols were determined. Oleic, palmitic, and linoleic acids were the main fatty acids. Desmethylsterols were the principal minor compounds with β-sitosterol being the most abundant component. Low amounts of aliphatic and terpenic alcohols were also found. The major tocopherol in hazelnut and sweet almond oils was α-tocopherol, whereas γ-tocopherol prevailed in pecan nut oil. Principal component analysis made it possible for us to differentiate among samples, as well as to distinguish between commercial and laboratory-extracted oils. Heatmap highlighted the main variables featuring each sample. Globally, these results have brought a new approach on nut oil characterization. Gabriel D. Fernandes, Raquel B. Gómez-Coca, María del Carmen Pérez-Camino, Wenceslao Moreda, and Daniel Barrera-Arellano Copyright © 2017 Gabriel D. Fernandes et al. All rights reserved. HPLC Quantification of Cytotoxic Compounds from Aspergillus niger Sun, 30 Apr 2017 08:17:11 +0000 http://www.hindawi.com/journals/jchem/2017/6969358/ A high-performance liquid chromatography method was developed and validated for the quantification of the cytotoxic compounds produced by a marine strain of Aspergillus niger. The fungus was grown in malt peptone dextrose (MPD), potato dextrose yeast (PDY), and mannitol peptone yeast (MnPY) media during 7, 14, 21, and 28 days, and the natural products were identified by standard compounds. The validation parameters obtained were selectivity, linearity (coefficient of correlation > 0.99), precision (relative standard deviation below 5%), and accuracy (recovery > 96). Paula Karina S. Uchoa, Leandro Bezerra de Lima, Antonia T. A. Pimenta, Maria da Conceição F. de Oliveira, Jair Mafezoli, and Mary Anne S. Lima Copyright © 2017 Paula Karina S. Uchoa et al. All rights reserved. Density Functional Theory Investigation into the B and Ga Doped Clean and Water Covered γ-Alumina Surfaces Wed, 26 Apr 2017 09:10:26 +0000 http://www.hindawi.com/journals/jchem/2017/6215315/ The structures and energies of the B and Ga incorporated -alumina surface as well as the adsorption of water are investigated using dispersion corrected density functional theory. The results show that the substitution of surface Al atom by B atom is not so favored as Ga atom. The substitution reaction prefers to occur at the tricoordinated A(4) sites. However, the substitution reaction becomes less thermodynamically favored when more Al atoms are substituted by B and Ga atoms on the surface. Moreover, the substitution of bulk Al atoms is not so favored as the Al atoms by B and Ga on the surface. The -alumina surface is found to have stronger adsorption ability for water than the B and Ga incorporated surface. The total adsorption energy increases as water coverage increases, while the stepwise adsorption energy decreases. The studies show the coverage of water at 7.5 H2O/nm2 (five H2O molecules per unit cell) can fully cover the active sites and the further water molecule could only be physically adsorbed on the surface. Lihong Cheng, Tianliang Xu, Wenkui Li, Zhiqin Chen, Jianping Ai, Zehua Zhou, and Jianwen Liu Copyright © 2017 Lihong Cheng et al. All rights reserved. Theoretical Analysis of the Effect Provoked by Bromine-Addition on the Thermolysis and Chemiexcitation of a Model Dioxetanone Wed, 26 Apr 2017 07:15:39 +0000 http://www.hindawi.com/journals/jchem/2017/1903981/ Chemi-/bioluminescence are phenomena in which chemical energy is converted into electronically excited singlet states, which decay with light emission. Given this feature, along with high quantum yields and other beneficial characteristics, these systems have gained numerous applications in bioanalysis, in biomedicine, and in the pharmaceutical field. Singlet chemiexcitation is made possible by the formation of cyclic peroxides (as dioxetanones) as thermolysis provides a route for a ground state reaction to produce singlet excited states. However, such thermolysis can also lead to the formation of triplet states. While triplet states are not desired in the typical applications of chemi-/bioluminescence, the efficient production of such states can open the door for the use of these systems as sensitizers in photocatalysis and triplet-triplet annihilation, among other fields. Thus, the goal of this study is to assess the effect of heavy atom addition on the thermolysis and triplet chemiexcitation of a model dioxetanone. Monobromination does not affect the thermolysis reaction but can improve the efficiency of intersystem crossing, depending on the position of monobromination. Addition of bromine atoms to the triplet state reaction product has little effect on its properties, except on its electron affinity, in which monobromination can increase between 3.1 and 8.8 kcal mol−1. Luís Pinto da Silva, Rui F. J. Pereira, and Joaquim C. G. Esteves da Silva Copyright © 2017 Luís Pinto da Silva et al. All rights reserved. Water Remediation Wed, 26 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/9292306/ Reyna Natividad-Rangel, Manuel A. R. Rodrigo, Julie J. M. Mesa, and Rosa M. G. Espinosa Copyright © 2017 Reyna Natividad-Rangel et al. All rights reserved. Stress Concentration in the Bulk Cr2O3: Effects of Temperature and Point Defects Mon, 24 Apr 2017 07:14:01 +0000 http://www.hindawi.com/journals/jchem/2017/7039436/ Modeling the growth and failure of passive oxide films formed on stainless steels is of general interest for the use of stainless steel as structural material and of special interest in the context of life time extension of light water reactors in nuclear power plants. Using the approach, a theoretical investigation on the resistance to failure of the chromium-rich inner oxide layer formed at the surface of chromium-containing austenitic alloys (stainless steel and nickel based alloys) has been performed. The investigations were done for periodic bulk models. The data at the atomic scale were extrapolated by using the Universal Binding Energy Relationships (UBERs) model in order to estimate the mechanical behavior of a 10 μm thick oxide scale. The calculated stress values are in good agreement with experiments. Tensile stress for the bulk chromia was observed. The effects of temperature and structural defects on cracking were investigated. The possibility of cracking intensifies at high temperature compared to 0 K investigations. Higher susceptibility to cracking was observed in presence of defects compared to nondefective oxide, in agreement with experimental observation. Mazharul M. Islam, Thierry Couvant, Philippe Marcus, and Boubakar Diawara Copyright © 2017 Mazharul M. Islam et al. All rights reserved. Enaminonitrile as Building Block in Heterocyclic Synthesis: Synthesis of Novel 4H-Furo[2,3-d][1,3]oxazin-4-one and Furo[2,3-d]pyrimidin-4(3H)-one Derivatives Thu, 20 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/5610707/ 2-Amino-4,5-diphenylfuran-3-carbonitrile 1 was utilized as building block for the construction of new furo[2,3-d]pyrimidin-4(3H)-one derivative 2 and 4H-furo2,3-d1,3oxazin-4-one derivative 3 via treatment with acetic anhydride and benzoyl chloride, respectively. The 4H-furo2,3-d1,3oxazin-4-one derivative 3 was transformed into novel furo[2,3-d]pyrimidin-4(3H)-ones 4–8, tetrazolylfuran derivative 10, and furo[3,2-d]imadazolone derivative 11 via reaction with various nitrogen nucleophiles. The structure features of the synthesized compounds were established from their spectral and elemental analyses. Manal M. El-Shahawi and Ahmed K. El-Ziaty Copyright © 2017 Manal M. El-Shahawi and Ahmed K. El-Ziaty. All rights reserved. Molecular Cloning and Expression Analysis of Cu/Zn SOD Gene from Gynura bicolor DC. Tue, 18 Apr 2017 08:07:36 +0000 http://www.hindawi.com/journals/jchem/2017/5987096/ Superoxide dismutase is an important antioxidant enzyme extensively existing in eukaryote, which scavenges reactive oxygen species (ROS) and plays an essential role in stress tolerance of higher plants. A full-length cDNA encoding Cu/Zn SOD was cloned from leaves of Gynura bicolor DC. by rapid amplification of cDNA ends (RACE). The full-length cDNA of Cu/Zn SOD is 924 bp and has a 681 bp open reading frame encoding 227 amino acids. Bioinformatics analysis revealed that belonged to the plant SOD super family. Cu/Zn SODs of the Helianthus annuus, Mikania micrantha, and Solidago canadensis var. scabra all have 86% similarity to the G. bicolor Cu/Zn SOD. Analysis of the expression of Cu/Zn SOD under different treatments revealed that Cu/Zn SOD was a stress-responsive gene, especially to 1-MCP. It indicates that the Cu/Zn SOD gene would be an important gene in the resistance to stresses and will be helpful in providing evidence for future research on underlying molecular mechanism and choosing proper postharvest treatments for G. bicolor. Xin Xu, Zhi-fang Yu, Jing Kong, Mei-jun Yi, Chen Huan, and Li Jiang Copyright © 2017 Xin Xu et al. All rights reserved. Study of Lactic Acid Thermal Behavior Using Thermoanalytical Techniques Tue, 18 Apr 2017 06:58:30 +0000 http://www.hindawi.com/journals/jchem/2017/4149592/ Actually, there is a growing interest in the biotechnological production of lactic acid by fermentation aiming to substitute fossil fuel routes. The development of an efficient method for its separation and purification from fermentation broth is very important to assure the economic viability of production. Due to its high reactivity and tendency to decompose at high temperatures, the study of lactic acid thermal behavior is essential for its separation processes and potential application. In the present study, differential scanning calorimetry (DSC) analyses showed endothermic peaks related to the process of evaporation. Data of thermogravimetry (TG/DTG) were correlated to Arrhenius and Kissinger equations to provide the evaporation kinetic parameters and used to determine the vaporization enthalpy. Activation energies were 51.08 and 48.37 kJ·mol−1 and frequency values were 859.97 and 968.81 s−1 obtained by Arrhenius and Kissinger equations, respectively. Thermogravimetry, coupled with mass spectroscopy (TG-MS), provided useful information about decomposition products when lactic acid was heated at 573 K for approximately 30 min. Andrea Komesu, Patricia Fazzio Martins Martinez, Betânia Hoss Lunelli, Johnatt Oliveira, Maria Regina Wolf Maciel, and Rubens Maciel Filho Copyright © 2017 Andrea Komesu et al. All rights reserved. Chemical and Oxygen Isotopic Composition of Roman and Late Antique Glass from Northern Greece Tue, 18 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/2956075/ The present paper emphasizes the importance of measuring the oxygen isotopic and chemical compositions of ancient glass, in order to constrain some features such as age, raw materials, and production technologies and to identify the “fingerprint” of local productions. In this context, thirty-nine Roman and late Antique glass samples and eight chert samples from northern Greece were selected and analysed for their oxygen isotopic and chemical compositions. Results show that the majority of glass samples are produced using natron as flux and have 18O values of about 15.5, plus or minus a few tenths of one per mil, suggesting that raw materials probably come from Levantine area. Four samples are heavily enriched in 18O, and their chemical composition clearly shows that they were made with soda plant ash as flux. Isotopic and chemical data of Greek chert samples support the hypothesis of local production of the above samples. About half of the glass samples have chemical compositions, which allow their age to be constrained to the late Antique period. For the remaining glass, similarities with literature compositional groups are reported and discussed. Alberta Silvestri, Elissavet Dotsika, Antonio Longinelli, Enricomaria Selmo, and Sophia Doukata-Demertzi Copyright © 2017 Alberta Silvestri et al. All rights reserved. Analytical Methods for the Determination of the Distribution of Total Petroleum Hydrocarbons in the Water and Sediment of Aquatic Systems: A Review Sun, 16 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/5178937/ Several methods of extraction and analytical determination for total petroleum hydrocarbons (TPHCs) in aqueous and solid samples are reviewed. Infrared spectroscopy is one of the efficient methods that are being replaced today pursuant to getting rid of some halogenated solvents classified as ozone-depleting substances. The gravimetric method which uses n-hexane as an extraction solvent for the determination of oil and grease, as well as the nonpolar materials, has become a preferred choice, despite being not suitable for volatiles because of the mandatory evaporation step. Other frequently used methods include gas chromatography with a flame ionization detector (FID) or mass spectrometric detector (MSD) which has the capacity to reveal the type of hydrocarbons present and is applicable to both volatile and semivolatile samples. Ultraviolet fluorescence is another method that is available both as a portable field device and as off-site laboratory equipment. Each of the methods has its own advantages and disadvantages; hence, the choice of method is guided by the type of data needed as discussed in detail in this review. The distribution of TPHC in water and sediments across the globe and the factors influencing the distribution were also reviewed. A. O. Adeniji, O. O. Okoh, and A. I. Okoh Copyright © 2017 A. O. Adeniji et al. All rights reserved. Application of Starch-Stabilized Silver Nanoparticles as a Colorimetric Sensor for Mercury(II) in 0.005 mol/L Nitric Acid Thu, 13 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/6897960/ A sensitive and selective Hg2+ optical sensor has been developed based on the redox interaction of Hg2+ with starch-coated silver nanoparticles (AgNPs) in the presence of 0.005 mol L−1 HNO3. The relative intensity of the localized surface plasmon absorption band of AgNPs at 406 nm is linearly dependent on the concentration of Hg2+ with positive slope for the concentration range 0–12.5 μg L−1 and negative slope for the concentration range 25–500 μg L−1. Experiments performed demonstrated that metal ions (Na+, K+, Mg2+, Ca2+, Pb2+, Cu2+, Zn2+, Cd2+, Fe3+, Co2+, and Ni2+) do not interfere under the same conditions, due to the absence of oxidative activity of these ions, which guarantees the high selectivity of the proposed optical sensor towards Hg2+. The limits of detection and quantification were found to be 0.9 µg L−1 and 2.7 µg L−1, respectively, and relative standard deviations varied in the range 9–12% for Hg content from 0.9 to 12.5 μg L−1 and 5–9% for Hg levels from 25 to 500 μg L−1. The method was validated by analysis of CRM Estuarine Water BCR505. A possible mechanism of interaction between AgNPs and Hg2+ for both concentration ranges was proposed on the basis of UV-Vis, TEM, and SAED analyses. Penka Vasileva, Teodora Alexandrova, and Irina Karadjova Copyright © 2017 Penka Vasileva et al. All rights reserved. Adsorption of Cr(VI) onto Hybrid Membrane of Carboxymethyl Chitosan and Silicon Dioxide Wed, 12 Apr 2017 06:14:19 +0000 http://www.hindawi.com/journals/jchem/2017/3426923/ In this study, a new adsorbent material was synthesized by using carboxymethyl chitosan and silicon dioxide. The hybrid membrane was used as an adsorbent for the removal of Cr(VI) from aqueous solutions. The adsorption potential of Cr(VI) by the hybrid materials was investigated by varying experimental conditions such as pH, contact time, and the dosage of the hybrid membrane. Adsorption isotherms of Cr(VI) onto the hybrid membrane were studied with varying initial concentrations under optimum experiment conditions. The surface property of the hybrid membrane was characterized by SEM (scanning electron microscope) and Fourier transform infrared spectrometer (FTIR). The concentrations of Cr(VI) in solution are determined by ICP-AES (inductively coupled plasma atomic emission spectrometry). The present study investigates the adsorption mechanisms of Cr(VI) onto the hybrid membrane. The results provide new insight, demonstrating that the modified hybrid membrane can be an efficient adsorbent for Cr(VI) from the aqueous solution. Yanling Deng, Naoki Kano, and Hiroshi Imaizumi Copyright © 2017 Yanling Deng et al. All rights reserved. Active Razor Shell CaO Catalyst Synthesis for Jatropha Methyl Ester Production via Optimized Two-Step Transesterification Wed, 12 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/jchem/2017/1489218/ Calcium based catalysts have been studied as promising heterogeneous catalysts for production of methyl esters via transesterification; however a few were explored on catalyst synthesis with high surface area, less particle size, and Ca leaching analysis. In this work, an active Razor shell CaO with crystalline size of 87.2 nm, of 92.63 m2/g, pore diameters of 37.311 nm, and pore volume of 0.613 cc/g was synthesized by a green technique “calcination-hydro aeration-dehydration.” Spectrographic techniques TGA/DTA, FTIR, SEM, XRD, BET&BJH, and PSA were employed for characterization and surface morphology of CaO. Two-step transesterification of Jatropha curcas oil was performed to evaluate CaO catalytic activity. A five-factor-five-level, two-block, half factorial, central composite design based response surface method was employed for experimental analysis and optimization of Jatropha methyl ester (JME) yield. The regression model adequacy ascertained thru coefficient of determination (: 95.81%). A JME yield of 98.80% was noted at (3.10 wt.%), (54.24 mol./mol.%), (127.87 min), (51.31°C), and (612 rpm). The amount of Ca leached to JME during 1st and 4th reuse cycles was 1.43 ppm ± 0.11 and 4.25 ppm ± 0.21, respectively. Higher leaching of Ca, 6.67 ppm ± 1.09, was found from the 5th reuse cycle due to higher dispersion of Ca2+; consequently JME yield reduces to 76.40%. The JME fuel properties were studied according to biodiesel standards EN 14214 and comply to use as green biodiesel. A. N. R. Reddy, A. A. Saleh, M. S. Islam, and S. Hamdan Copyright © 2017 A. N. R. Reddy et al. All rights reserved.