Efficient separation of Cinnamomum camphora leaf essential oil and in vitro evaluation of its antifungal activity

Cinnamomum camphora leaf essential oil (CEO) was extracted using enzymatic-ultrasound pretreatment followed by microwave assisted extraction (EUP-MAE) method and simultaneously studied as a mycelial growth inhibitor against five important pathogens which cause potato dry rot. The optimum EUP-MAE conditions with a real CEO yield of 19.23 ± 0.12 mg/g were obtained through Plackett–Burman design and Box–Behnken design as follows: 3 % of enzyme dosage, 2 h of pretreatment time, 5 of pH, 210 W of ultrasound power, 50 °C pretreatment temperature, 16 mL/g of water to solid ratio, 30 min of microwave time and 500 W of microwave power. Compared to the reference methods, EUP-MAE possessed a highest CEO yield than these of ultrasound-microwave assisted extraction (U-MAE) and traditional hydrodistillation (HD). Gas chromatography-mass spectrometry (GC–MS) analysis demonstrated that eucalyptol, camphor, and α-terpineol were the three main constituents of CEO. Results from in vitro antifungal activity assay revealed that the mycelial growths of all the five tested Fusarium solani, Fusarium culmorum, Fusarium trichothecioides, Fusarium sporotrioides, and Fusarium avenaceum were apparently affected by CEO. These findings not only provide a potential paradigm for the separation of plant essential oil, but also guarantee a promising utilization of the CEO for potato protection to control the Fusarium spp.     

Existence and uniqueness of perturbed reflected jump diffusion processes

In this article, we establish the existence of the solution to the càdlàg perturbed Skorohod problem. As an application, we obtain the existence and uniqueness of the solution to the perturbed reflected jump diffusion processes.     

Electrochemical recognition of tryptophan enantiomers using self-assembled diphenylalanine structures induced by graphene quantum dots,chitosan and CTAB

Molecular self-assembly offers a promising route to the preparation of advanced materials for the construction of novel chiral sensing devices, and the inspiration for the development of such systems is often derived from simple biological models. Diphenylalanine (FF), an extensively studied short peptide, can self-assemble into highly ordered nano-/micro-structures. Here we report the electrochemical recognition of tryptophan enantiomers using three FF self-assembled structures produced in the presence of graphene quantum dots (GQDs), chitosan (CS) and cetyltrimethylammonium bromide (CTAB). Although the difference in the peak potentials of the enantiomers is very small, enantiomeric differences can be detected by the magnitude of the DPV current signals. The recognition efficiencies of the three self-assembled materials are different, due to the different structures formed during the self-assembly process.     

Aerial Oxygen-Driven Selenocyclization of O-Vinylanilides Mediated by Coupled Fe3+/Fe2+ and I2/I− Redox Cycles

In the past decade, selenocyclization has been extensively exploited for the preparation of a wide range of selenylated heterocycles with versatile activities. Previously, selenium electrophile-based and FeCl₃-promoted methods were employed for the synthesis of selenylated benzoxazines. However, these methods are limited by starting material availability and low atomic economy, respectively. Inspired by the recent catalytic selenocyclization approaches based on distinctive pathways, we rationally constructed an efficient and greener double-redox catalytic system for the access to diverse selenylated benzoxazines. The coupling of I₂/I⁻ and Fe³⁺/Fe²⁺ catalytic redox cycles enables aerial O₂ to act as the driving force to promote the selenocyclization. Control and test redox experiments confirmed the roles of each component in the catalytic system, and a PhSeI-based pathway is proposed for the selenocyclization process.     

Substituted benzeneseleninic acids as bidentate ligands. Synthesis and spectroscopic studies of manganese(II) and iron(II) complexes

The para- and meta-substituted seleninato anion, XC₆H₄SeO⁻₂, forms complexes with manganese(II) and iron(II) of the type [M(XC₆H₄SeO₂)₂(H₂O)₂], which have been shown to contain the bidentate ligand in seleninato-_O, O′ derivatives, the water molecules being coordinated to the metals. From the electronic absorption spectra and from the magnetic susceptibility data we have proposed for all the complexes a distorted octahedral D_4h symmetry. The structure of the anhydrous para- and meta-substituted benzeneseleninato complexes of manganese(II) and iron(II) have been investigated by means of electrical conductance measurements, spectral (electronic and i.r.) studies and magnetic susceptibility measurements. The anhydrous complexes are always of the seleninato-O, O′ type with the ligands tetrahedrally coordinated to the central atom. The wavelengths of the principal absorption peaks have been accounted for quantitatively in terms of the crystal field theory for manganese(II) derivatives. The nephelauxetic parameters are all indicative of an appreciable metal-ligand covalency.     

Structure and internal rotation in 3-phenylthiophene using NMR spectra of liquid-crystalline solutions

The NMR spectra of 3-phenylthiophene as solute in liquid-crystal solvents were analyzed and the direct couplings constants, D_ij obtained were used to test different models of the potential energy function V(φ) for intramolecular rotation of the phenyl and thiophene units. The data are consistent with a V(φ) having a minimum at about 24°. The LCNMR technique is highly discriminant among different models of V(φ) provided that enough D_ij couplings are available. Ab initio calculations are also reported.     

Nomographs for evaluating parameters of Schottky Barrier I.R. Detectors

Nomographs have been developed in this paper for direct evaluation of various parameters at 77K of Schottky barrier infrared detectors. Similar nomographs can also be constructed for other temperatures.     

单层2H-MoTe2光电效应的理论研究

材料的禁带宽度是影响光电探测器探测范围的重要因素.单层2H-MoTe2因具有合适的禁带宽度引起了科研人员广泛的研究兴趣.本文基于非平衡态格林函数-密度泛函理论,采用第一性原理方法,研究了单层2H-MoTe2的光电效应.结果表明:在线性偏振光照射下,MoTe2产生的光电流函数与唯象理论相吻合;在光子能量范围1.6～1.8...     

Effet Kerr magnetique microonde du type Faraday dans les semiconducteurs

The Faraday-type magneto-microwave Kerr effect in semiconductors at weak magnetic fields has been studied in the domain where the influence of the carrier inertia is low but not negligible. After stating the expressions connecting the rotation and the ellipticity of the reflected wave to the material parameters we have applied these results to the determination of Hall mobility and shown that a precise determination of this mobility must usually be realised from both rotation and ellipticity effects.The experimental study has been achieved with a recording interferential reflecto-polarimeter. This apparatus being particularly well suited to this study has not yet been used for this kind of measurements. We have thus determined precisely the Hall mobility of various semiconductor samples at 16 GHz and at room temperature.