Reduced Graphene Oxide|Carbon Ceramic Electrode Modified with CdS‐Hemoglobin as a Sensitive Hydrogen Peroxide Biosensor

A sensitive hydrogen peroxide (H₂O₂) biosensor was developed based on a reduced graphene oxide|carbon ceramic electrode (RGO|CCE) modified with cadmium sulfide‐hemoglobin (CdS‐Hb). The electron transfer kinetics of Hb were promoted due to the synergetic function of RGO and CdS nanoparticles. The transfer coefficient (α) and the heterogeneous electron transfer rate constant (k_s) were calculated to be 0.54 and 2.6 s^?1, respectively, indicating a great facilitation achieved in the electron transfer between Hb and the electrode surface. The biosensor showed a good linear response to the reduction of H₂O₂ over the concentration range of 2–240 µM with a detection limit of 0.24 µM (S/N=3) and a sensitivity of 1.056 µA µM^?1 cm^?2. The high surface coverage of the CdS‐Hb modified RGO|CCE (1.04×10^?8 mol cm^?2) and a smaller value of the apparent Michaelis? Menten constant (0.24 mM) confirmed excellent loading of Hb and high affinity of the biosensor for hydrogen peroxide.     

Measurement of impurity and temperature variations in water by interferometry technique

Refractive index is an important optical parameter of liquids, which is temperature, concentration and wavelength-dependent. Therefore, precise measurement of refractive index variation can be used for precise determination of the above parameters. In this paper a laser-based interferometry technique was introduced for accurate measuring of the refractive index variation due to temperature, and concentration changes. Distilled water was used as a test liquid sample, however the technique can be applied for any similar liquids. The concentration variations of distilled water due to three different impurities i.e. ethanol, salt water and tap water were examined. The technique gives measurement for concentration and temperature variations typically at the order ∼10⁻⁴(g/l)⁻¹ and 10⁻⁵ K⁻¹ respectively. The results show the variations of refractive index with respect to temperature or concentration can be measured typically with an accuracy of ∼6%, and 10% respectively. The method is useful for fast and precise monitoring of temperature and concentration variations in transparent liquids.     

Investigation of beam characteristics in toric unstable optical resonator

In this paper the characteristics of the output beam of a toric unstable resonator are investigated. Based on the Fresnel–Kirchhof integral and using numerical methods, the performance of toric unstable resonators is simulated and its output beam characteristics are also evaluated. Geometrical resonator parameters, i.e. Fresnel number and magnification as well as the output coupler diameter, are considered in this investigation. The radial and azimuthal modes of the resonator are calculated and the modal behavior of the resonator is described according to geometrical parameters. The power extraction for each specific laser mode has also been inspected by calculating the finesse factor. Using an iteration mode convergence diagram, the mode discrimination of the resonator is investigated.     

Environmental supply chain network design using multi-objective fuzzy mathematical programming

The concern about environmental impact of business activities has spurred an interest in designing environmentally conscious supply chains. This paper proposes a multi-objective fuzzy mathematical programming model for designing an environmental supply chain under inherent uncertainty of input data in such problem. The proposed model is able to consider the minimization of multiple environmental impacts beside the traditional cost minimization objective to make a fair balance between them. A life cycle assessment-based (LCA-based) method is applied to assess and quantify the environmental impact of different options for supply chain network configuration. Also, to solve the proposed multi-objective fuzzy optimization model, an interactive fuzzy solution approach is developed. A real industrial case is used to demonstrate the significance and applicability of the developed fuzzy optimization model as well as the usefulness of the proposed solution approach.     

Organocatalytic approach toward the green one-pot synthesis of novel benzo[<Emphasis Type="Italic">f</Emphasis>]chromenes and 12<Emphasis Type="Italic">H</Emphasis>-benzo[5,6]chromeno[2,3-<Emphasis Type="Italic">b</Emphasis>]pyridines

An efficient tandem reaction approach is described to prepare novel benzo[f]chromenes from 2,3-dihydroxynaphthalene, malononitrile and aldehydes using 10 mol% guanidine hydrochloride as the catalyst under solvent-free conditions. The method was also extended to the preparation of novel 12H-benzo[5,6]chromeno[2,3-b]pyridines from 2-aminoprop-1-ene-1,1,3-tricarbonitrile instead of malononitrile under the same reaction conditions. The described one-pot three-component reaction is characterized by short reaction times, high-product yield, mild reaction conditions, simple workup procedure, and simple purification.     

Highly Selective and Sensitive Electrochemical Determination of Ni(II) in Real Samples Based on Ion‐imprinted Polymer Technology

Nickel is one of the heavy metals which has been considered as a serious pollutant affecting the human health. Therefore, it is necessary to control its concentration in foods and drinks. Recently, ion‐imprinted polymer based electrochemical sensors have been attracted lots of attention due to their valuable selectivity and sensitivity toward target analytes. In this study, Ni(II)‐1,10‐phenanthroline complex was prepared in ethanol and added stepwise to the aqueous solution of dopamine, followed by pH adjustment for self‐polymerization of dopamine in alkaline conditions. During the polymerization process, Ni(II)‐imprinted polydopamine (Ni‐PDA) was formed due to effective interactions between polydopamine and 1,10‐phenanthroline ligands carrying Ni(II) ions. A thin film of Ni‐PDA was anchored on a glassy carbon electrode (GCE) through a simple casting procedure. After drying, the sensor was employed for the determination of Ni(II) ions by means of differential pulse voltammetry. Under optimum conditions, a linear calibration curve was obtained in the range 1–25 μM with the detection limit of 0.39 μM (S/N=3). Due to excellent selectivity to Ni(II) ions, the sensor was not suffered from the excess amount of interfering ions and used for Ni(II) determination in different water and tea samples.     

A novel and efficient synthesis of pyrazolo[3,4-d]pyrimidine derivatives and the study of their anti-bacterial activity

In this work 4-amino-6-aryl-2-phenyl pyrimidine-5-carbonitrile derivatives were synthesized through a one-pot,three-component reaction of an aldehyde,malononitrile and benzamidine hydrochloride,in the presence of magnetic nano Fe₃O₄ particles as a catalyst under solvent-free conditions.3-Amino-6-aryl- 2-phenylpyrazolo[3,4-d]pyrimidine derivatives were prepared through an efficient and environmentally friendly reaction between 4-amino-6-aryl-2-phenylpyrimidine-5-carbonitrile derivatives and hydrazine hydrate and their antibacterial activity has been evaluated.     

One-Pot Green Synthesis of Novel Polysubstituted 1,2-Dihydronaphtho[2,1-b]furans

A simple and highly efficient one-pot protocol for the synthesis of novel polysubstituted 1,2-dihydronaphtho[2,1-b] furans has been developed by three-component coupling reaction of 2-aminopyridines, naphthols, and glyoxal in the presence of guanidinium chloride as a polyfunctional organocatalyst under solvent-free conditions. The protocol avoids the use of expensive catalysts, toxic solvents, and chromatographic separation and provides a wide range of novel dihydronaphthofurans in good to excellent yields.