Enhanced Sensitive Electrochemical Sensor for Simultaneous Catechol and Hydroquinone Detection by Using Ultrasmall Ternary Pt-based Nanomaterial

The simple and effective method for the novel synthesis of Pt-based nanoparticle was presented with high efficiency. The sensitive catalyst for the simultaneous detection of catechol and hydroquinone was prepared by depositing ternary metal complex on fluorine-doped tin-oxide (FTO). The composition and morphology of nanomaterials were characterized by TEM, HRTEM, XRD, XPS, and EDS (energy dispersive spectroscopy). The size of the Pt-based nanomaterial was about 5±1 nm. The electrochemical performance of the modified catalyst was studied by CV, DPV, and EIS. The modified PtNiCu@FTO catalyst possessed good electro-oxidation activity for hydroquinone and catechol and used for simultaneous detection of catechol and hydroquinone at scan rate of 20 mV s⁻¹ (vs. Ag/AgCl). Detection responses were found in the ranges of 5–2900 μM for hydroquinone and 5–3000 μM for catechol. The detection limits (LOD) for HQ and CC were observed as 0.35 and 0.29 μM, respectively. The sensitivity of HQ and CC were 1515.55 and 1485 μA mM⁻¹ cm⁻², respectively. The prepared nanomaterial were effectively applied for the determination of CC and HQ in real samples.     

Development of a new synthesis approach for S-pregabalin by optimizing the preparation stages

Journal of the Iranian Chemical Society - In the present study, we aimed to optimize the synthesis stages of S-pregabalin ((S)-3-(aminomethyl)-5-methylhexanoic acid), a well-known anticonvulsant...     

New pH-Sensitive Hydrogels for Oral Delivery of Hydrophobic Drugs

A series of acrylic copolymers containing silyl pendant groups was prepared by free radical cross-linking copolymerization. Me₃Si, Et₃Si, and Ph₃Si together with cubane-1,4-dicarboxylic acid (CDA) were covalently linked with 2-hydroxyethyl methacrylate (HEMA). CDA linked to two HEMA group is the cross-linking agent (CA). Free radical cross-linking copolymerization of the methacrylic acid (MAA) and organosilyl monomers with two different molar ratios of CA was carried out at 60–70°C. The compositions of the cross-linked three-dimensional polymers were determined by FT-IR spectroscopy. The glass transition temperature of the network polymers was determined calorimetrically. Equilibrium swelling studies were carried out in enzyme-free simulated gastric and intestinal fluids (SGF and SIF, respectively). A model hydrophobic drug, the steroid hormone estradiol, was entrapped in these gels, and the in vitro release profiles were established separately in both SGF (pH 1) and SIF (pH 7.4). Incorporation of silyl groups in a new macromolecule system modified network polymers for drug delivery.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Agar-based heat-sensitive gel with linear thermal response over 65–80 °C

A nontoxic heat-sensitive gel containing 1.5 % (w/v) agar and 25 % (w/v) bovine serum albumin (BSA) was fabricated in this study. Optical density measurements with 808 nm near-infrared (NIR) laser indicated that, in spite of its BSA content, the current agar + BSA gel remained similar to agar only gel in terms of its optical response to NIR laser. The thermal response of the current agar + BSA gel to high temperatures was quantified using magnetic resonance imaging (MRI). According to the MRI measurements of T2 relaxation rate as a function of heating temperature, the current agar + BSA gel showed a linear response to heating temperatures between 65 and 80 °C, while it remained thermally stable at temperatures up to 80 °C. Therefore, the current agar + BSA gel can be used as thermal dosimeters or volumetric heat-sensitive gel phantoms in typical thermal therapy regime.     

Conformational space of tetrakis(2-naphthalenyl)ethene: a naphthologous AIE luminogen

The AIE luminogen tetrakis(2-naphthalenyl)ethene (2-NA ₄ E) was synthesized by Barton’s double extrusion diazo-thione coupling method from 2,2′-dinaphthyl thioketone and 2,2′-(diazomethylene)bisnaphthylene in 77 % yield. The structure of 2-NA ₄ E was confirmed by its ¹H NMR and ¹³C NMR spectra with full assignments. 2-NA ₄ E and its parent tetraphenylethene (Ph ₄ E) have been subjected to a comprehensive computational DFT study, in search of their conformational spaces. Seven conformers and two transition states of 2-NA ₄ E have been located. Four conformers and one transition state of Ph ₄ E have been located. The conformers of 2-NA ₄ E and Ph ₄ E are not overcrowded, as indicated by the contact distances in the fjord and cove regions. The relative free energies (ΔG ₂₉₈) of the six most stable conformers of 2-NA ₄ E are in the narrow range of 2.3 kJ/mol; they make comparable contributions (12–29 %) to the equilibrium mixture. The energy barriers for the diastereomerization D ₂-Z,Z,Z,Z $ \rightleftharpoons $ ? D ₂-E,E,E,E via the transition state C ₁-Z,E,E,Z and for the enantiomerization C ₂-Z,Z,E,E $ \rightleftharpoons $ ? C ₂-E,E,Z,Z via the transition state C _i -Z,E,Z,E are only 29.8 and 29.0 kJ/mol, respectively, indicating very rapid rates of diastereomerization and enantiomerization at room temperature. The values of naphthalenyl torsion angles and ethenic twist angles in 2-NA ₄ E are almost identical to those in the parent Ph ₄ E. The previously proposed “bulkiness” of the naphthalenyl substituents and the validity of the restriction of naphthalenyl rotation are challenged. The analysis of the AIE effect in 2-NA ₄ E should take into account the intermolecular homochiral and heterochiral interactions between the conformers.     

A CFD analysis on the effect of tube curvature,hot flow control valve profile,and inlet swirl on the thermal performance of curved vortex tubes

Journal of Thermal Analysis and Calorimetry - The influence of tube curvature, conical valve geometry, and initial swirl on the thermal performance of vortex tubes is numerically investigated....     

Synthesis of New Lipid‐Inspired Ionic Liquids by Thiol‐ene Chemistry: Profound Solvent Effect on Reaction Pathway

The synthesis of a series of new lipid‐inspired ionic liquids through thiol‐ene “click” reaction with a single‐step process. This synthesis offers considerable promise as an efficient and orthogonal method to construct structurally diverse imidazolium‐type ionic liquids with linear and branched cationic tails, as well as versatility in the placement of the sulfur heteroatom. Profound solvent effect in this ene reaction regioselectivity has been observed.     

Anti-glycating and anti-oxidant compounds from traditionally used anti-diabetic plant Geigeria alata(DC) Oliv. & Hiern.

Abstract

A new sesquiterpene lactone geigerianoloide (1) and four known flavonoids axillarin (2), quercetin (3), 3-methoxy-5,7,3',4'-tetrahydroxy-flavone (4) and hispidulin (5) were isolated from Geigeria alata (DC) Oliv. & Hiern. (Asteraceae). Structures were deduced using ¹H- and ¹³C- NMR spectroscopy, mass spectrometry, while the structure of compound 1 was also deduced using X-ray crystallography technique.

Geigeria alata is traditionally used for diabetes, therefore compounds were tested for anti-glycation activity, in which compounds 2 and 3 showed potent activities (IC₅₀ values of 246.97?±?0.83 and 262.37?±?0.22 µM, respectively) compared to IC₅₀ value 294.50?±?1.5 µM of rutin. Moreover, compound 4 exhibited a comparable activity to rutin (IC₅₀?=?293.28?±?1.34 µM). Compound 5 showed a weak activity.

Compounds 2, 3, and 4 exhibited potent DPPH radical scavenging activity (IC₅₀?=?0.1?±?0.00, 0.13?±?0.00 and 0.15?±?0.01 µM, respectively). Compounds 2, 3, and 4 demonstrated significant superoxide anion scavenging activity with IC₅₀ values of 0.14?±?0.001, 0.17?±?0.00, and 0.11?±?0.006 µM, respectively.     

Radiation transport with anisotropic scattering

Reflection and transmission of radiation with anisotropic scattering in considered, using an invariant-imbedding formulation of the transport equation. Extensive numerical calculations show that the results of the transport approximation, in which the scattering kernel is represented by an isotropic part and a forward scattered component, are useful for an isotropic incident source but they are not satisfactory for a monodirectional source, especially in the case of reflection for large and small incident angles. A modified transport approximation is proposed in which singly-scattered radiation is taken into account exactly and higher-order scatterings are obtained from the transport approximation. The results derived from the modified transport approximation are in good agreement with other calculations for the cases considered.