Total synthesis of (+/-)-4'-demethylmacrophyllol, a naturally occurring compound

The naturally occurring compound 4'-Demethylmacrophyllol (1), 8-Hydroxy-3-(4-hydroxy-3,5-dimethoxy-phenyl)-isochroman-1-one, was synthesized starting from 4-benzyloxy-3,5-dimethoxybenzaldehyde (3) and a phosphonium salt (2) in four steps with an overall yield of 44%. This is the first report on the total synthesis of 4'-demethylmacrophyllol (1). The structures of compounds were determined by NMR and MS and elemental analysis techniques.     

Three-dimensional nanofabrication with elastomeric phase masks

This Feature Article reviews recent work on an optical technique for fabricating, in a single exposure step, three-dimensional (3D) nanostructures with diverse structural layouts. The approach, which we refer to as proximity field nanopatterning, uses conformable, elastomeric phase masks to pattern thick layers of transparent, photosensitive materials in a conformal contact mode geometry. Aspects of the optics, the materials, and the physical chemistry associated with this method are outlined. A range of 3D structures illustrate its capabilities, and several application examples demonstrate possible areas of use in technologies ranging from microfluidics to photonic materials to density gradient structures for chemical release and high-energy density science.     

On the Additive Group Structure of the Nonstandard Models of the Theory of Integers

Let $\hat \mathbb{Z}$ denote the inverse limit of all finite cyclic groups. Let F, G and H be abelian groups with H ≤ G. Let FβH denote the abelian group (F × H, +^β), where +^βis defined by (a, x) +^β (b, y) = (a + b, x + y + β(a) + β(b) — β(a + b)) for a certain β : F → G linear mod H meaning that β(0) = 0 and β(a) + β(b) — β(a + b) ∈ H for all a, b in F. In this paper we show that the following hold: (1) The additive group of any nonstandard model ℤ* of the ring ℤ is isomorphic to (ℤ*₊/H)βH for a certain β : ℤ*₊/H → $\hat \mathbb{Z}$ linear mod H. (2) $\hat \mathbb{Z}$ is isomorphic to (ℤ₊/H )βH for some β : $\hat \mathbb{Z}$/H →ℚ linear mod H, though $\hat \mathbb{Z}$ is not the additive group of any model of Th(ℤ, +, ×) and the exact sequence H → $\hat \mathbb{Z}$ → $\hat \mathbb{Z}$/H is not splitting.     

In vitro study on the competitive reactions between arsenite and selenite with glutathione

Exposure to arsenic can cause various biological effects by increasing the production of reactive oxygen species (ROS). Selenium acts as a beneficial element by regulating ROS and limiting heavy metal uptake and translocation. There are studies on the interactive effects of As and Se in plants, but the antagonistic and synergistic effects of these elements based on their binding to glutathione (GSH) molecules have not been studied yet. In this study, we aimed to investigate the antagonistic or synergistic effects of As and Se on the binding mechanism of Se and As with GSH at pH 3.0, 5.0, or 6.5. The interaction of As and Se in Se(SG)₂ + As(III) or As(SG)₃ + Se(IV) binary systems and As(III) + Se(IV) + GSH ternary system were examined depending on their ratios via liquid chromatography diode array detector/electrospray mass spectrometry (LC-DAD/MS) and liquid chromatography–electrospray ionization–tandem mass spectrometry (LC-ESI-MS/MS). The results showed that the formation of As(GS)₃ was not detected in the As(III) + Se(SG)₂ binary system, indicating that As(III) did not affect the stability of Se(SG)₂ complex antagonistically. However, in the Se(IV) + As(SG)₃ binary system, the addition of Se(IV) to As(SG)₃ affected the stability of As(SG)₃ antagonistically. Se(IV) reacted with GSH, disrupting the As(SG)₃ complex, and consequently, Se(SG)₂ formation was measured using LC-MS/DAD. In the Se(IV) + GSH + As(III) ternary system, Se(SG)₂ formation was detected upon mixing As(III), Se(IV), and GSH. The increase in the concentration of As(III) did not influence the stability of the Se(SG)₂ complex. Additionally, Se(IV) has a higher affinity than As(III) to the GSH, regardless of the pH of the solution. In both binary and ternary systems, the formation of the by-product glutathione trisulfide (GSSSG) was detected using LC-ESI-MS/MS.     

Bismut(II)-chalkogenometallate(III) Bi2M4X8, Verbindungen mit Bi24+-Hanteln (M = Al,Ga; X = S,Se)

Bismuth(II) Chalcogenometallates(III) Bi₂M₄X₈, Compounds with Bi₂⁴⁺ Dumbbells (M = Al, Ga and X = S, Se) The ternary bismuth(II) chalcogenometallates(III) Bi₂M₄X₈ (with M = Al, Ga and X = S, Se) were synthesized from the binary chalcogenides M₂X₃ and Bi₂X₃ and elementary bismuth. All compounds are diamagnetic semiconductors with E_g (opt.) = 1.8–2.7 eV. The phases (except Bi₂Al₄Se₈) are thermodynamically stable and decompose peritectically above 965–1020 K. Bi₂Al₄Se₈ is metastable below 825 K and is obtained only by rapid quenching from T > 825 K. The isotypic compounds crystallize in a new tetragonal tP28 structure type (P4/nnc). The characteristic unit is the hitherto unknown clustercation Bi₂⁴⁺, with the mean bond length d(Bi–Bi) = 314.2 pm, the Raman frequency 102 cm^–1 ≤ ν_s ≤ 108 cm^–1, and the mean force constant of f = 0.68 N · cm^–1. The Electron Localization Function, ELF, shows the covalent Bi–Bi bond, the lone electron pairs of the ψ-octahedrally coordinated Bi(II) cations, and the polar character of the Bi–X bonds.     

Multilevel Deep Feature Generation Framework for Automated Detection of Retinal Abnormalities Using OCT Images

Optical coherence tomography (OCT) images coupled with many learning techniques have been developed to diagnose retinal disorders. This work aims to develop a novel framework for extracting deep features from 18 pre-trained convolutional neural networks (CNN) and to attain high performance using OCT images. In this work, we have developed a new framework for automated detection of retinal disorders using transfer learning. This model consists of three phases: deep fused and multilevel feature extraction, using 18 pre-trained networks and tent maximal pooling, feature selection with ReliefF, and classification using the optimized classifier. The novelty of this proposed framework is the feature generation using widely used CNNs and to select the most suitable features for classification. The extracted features using our proposed intelligent feature extractor are fed to iterative ReliefF (IRF) to automatically select the best feature vector. The quadratic support vector machine (QSVM) is utilized as a classifier in this work. We have developed our model using two public OCT image datasets, and they are named database 1 (DB1) and database 2 (DB2). The proposed framework can attain 97.40% and 100% classification accuracies using the two OCT datasets, DB1 and DB2, respectively. These results illustrate the success of our model.     

A simple technique for constructing exact solutions to nonlinear differential equations with conformable fractional derivative

The modified simple equation method is an interesting technique to find new and more general exact solutions to the fractional differential equations in nonlinear sciences. In this paper, the method is applied to construct exact solutions of (2+1)-dimensional conformable time-fractional Zoomeron equation and the conformable space-time fractional EW equation.     

Selective metal sensor phthalocyanines bearing non-peripheral functionalities: Synthesis,spectroscopy, electrochemistry and spectroelectrochemistry

A novel alcohol-soluble ionophore ligand and its non-peripherally tetrasubstituted functional 1,8,15,22-tetrakis(6-hydroxyhexylsulfanyl) metallophthalocyanines M[Pc(α-SC₆H₁₂OH)₄] (M = Cu(II), Zn(II), Co(II); Pc = phthalocyanine) are reported. The aggregation and cation binding behaviors of the phthalocyanine compounds in the presence of soft Ag^I and Pd^II metal ions were investigated by using UV–Vis spectroscopy. The new compounds have been characterized by elemental analysis, IR, ¹H, ¹³C NMR, UV/Vis spectroscopy, ESI and MALDI–TOF–MS mass spectra. Voltammetric and in-situ spectroelectrochemical studies show that while copper and zinc phthalocyanine complexes give well-defined ring-based reduction and oxidation processes, the cobalt phthalocyanine gives both metal-based and ring-based redox processes which have reversible and diffusion controlled character.     

Synthesis, characterization and biological evaluation of a novel Cu(II) complex with the mixed ligands 2,6-pyridinedicarboxylic acid and 2-aminopyridine

A novel bridged binuclear Cu(II) complex with mixed ligands, di-μ-(2-aminopyridine(N,N′))-bis[(2,6-pyridinedicarboxylate)aquacopper(II)] tetrahydrate, formulated as [Cu(μ-ap)(dipic)(H₂O)]₂·4H₂O (1) (dipic = 2,6-pyridinedicarboxylate, ap = 2-aminopyridine), has been synthesized and characterized by elemental, spectral (IR and UV–Vis.), thermal analysis, magnetic measurements and single crystal X-ray diffraction analysis. The central Cu(II) ion resides on a centre of symmetry in a distorted square-pyramid coordination environment comprising of two N atoms, one from dipic and one from the ap ring, two carboxylate O atoms from dipic, and one O atom from water. Intermolecular N–HO and O–HO hydrogen bonds and π–π stacking interactions seem to be effective in the stabilization of the crystal structure. The free ligands and the complex were also evaluated for their antimicrobial and radical scavenging activities (DPPH = 1,1-diphenyl-2-picrylhydrazyl hydrate) using in vitro microdilution methods. Antimicrobial screening of the free ligands and their complex showed that the free ligands and the complex possess antifungal activity against Candida sp.     

Chemoselective Boron–Carbon Bond Cleavage by Hydroboration of Borirenes

We report on the hydroboration of 1‐[bis(trimethylsilyl)amino]‐2,3‐diethylborirene ( 3 ) with 9‐borabicyclo[3.3.1]nonane (9‐BBN), which led through ring‐opening to an amino(vinyl)borane. The viscous borane was subsequently converted into a crystalline borate on treatment with MeLi. Both compounds were fully characterized by multinuclear NMR spectroscopy and in case of the latter by single‐crystal X‐ray diffraction analysis. To elucidate the reaction mechanism of the unexpected boron‐carbon bond cleavage, DFT calculations of energy minima and transition states for the hydroboration were carried out.