Surface plasmon band tailoring of plasmonic nanostructure under the effect of water radiolysis by synchrotron radiation

Plasmonic metal nanostructures have a significant impact on a diverse domain of fields, including photocatalysis, antibacterial, drug vector, biosensors, photovoltaic cell, optical and electronic devices. Metal nanoparticles (MNps) are the simplest nanostructure promising ultrahigh stability, ease of manufacturing and tunable optical response. Silver nanoparticles (AgNp) dominate in the class of MNps because of their relatively high abundance, chemical activity and unique physical properties. Although MNps offer the desired physical properties, most of the synthesis and fabrication methods lag at the electronic grade due to an unbidden secondary product as a result of the direct chemical reduction process. In this paper, a facile protocol is presented for fabricating high‐yield in situ plasmonic AgNps under monochromatic X‐rays irradiation, without the use of any chemical reducing agent which prevents the formation of secondary products. The ascendancy of this protocol is to produce high quantitative yield with control over the reaction rate, particle size and localized surface plasmon resonance response, and also to provide the feasibility for in situ characterization. The role of X‐ray energy, beam flux and integrated dose towards the fabrication of plasmonic nanostructures has been studied. This experiment extends plasmonic research and provides avenues for upgrading production technologies of MNps.     

Trichloroisocyanuric acid mediated one-pot synthesis of 3,5-diarylisoxazoles from α,β-unsaturated ketones

A facile one-pot synthesis of 3,5-diarylisoxazoles from α,β-unsaturated ketones and hydroxylamine hydrochloride is reported. The reaction is efficiently promoted by trichloroisocyanuric acid (TCCA) to afford the desired products, mostly in high yields and in relatively short time. The mild nature of the synthesis and short reaction time are notable advantages of the developed protocol. This protocol is effective towards various substrates having different functionalities.     

Chaos in a non-autonomous nonlinear system describing asymmetric water wheels

We derive a water wheel model from first principles under the assumption of an asymmetric water wheel for which the water inflow rate is in general unsteady (modeled by an arbitrary function of time). Our model allows one to recover the asymmetric water wheel with steady flow rate, as well as the symmetric water wheel, as special cases. Under physically reasonable assumptions, we then reduce the underlying model into a non-autonomous nonlinear system. In order to determine parameter regimes giving chaotic dynamics in this non-autonomous nonlinear system, we consider an application of competitive modes analysis. In order to apply this method to a non-autonomous system, we are required to generalize the competitive modes analysis so that it is applicable to non-autonomous systems. The non-autonomous nonlinear water wheel model is shown to satisfy competitive modes conditions for chaos in certain parameter regimes, and we employ the obtained parameter regimes to construct the chaotic attractors. As anticipated, the asymmetric unsteady water wheel exhibits more disorder than does the asymmetric steady water wheel, which in turn is less regular than the symmetric steady state water wheel. Our results suggest that chaos should be fairly ubiquitous in the asymmetric water wheel model with unsteady inflow of water.     

Chaotic behavior of logistic map in superior orbit and an improved chaos-based traffic control model

With a vital role of discrete chaos, standard logistic map has found a celebrated place in the dynamics of chaos theory and in various applications of science, such as a discrete traffic flow model, image encryption in cryptography, secure communication, and weather forecasting. Traditionally, this discrete chaos is controlled by one parameter \(\lambda \) using Picard orbit, a one-step feedback procedure. This article presents a one-step forward, applying Mann orbit (superior orbit) the chaotic properties such as period-doubling, period-3 window, and Lyapunov exponent of the standard logistic map is investigated. The results are illustrated analytically and experimentally followed by concluding remarks and a few counter examples. Due to the extra degree of freedom in parameter \(\lambda \), the map provides improved chaotic properties that increases the performance of dynamical phenomena. Moreover, this study describes an improved chaos-based discrete traffic control model. Surprisingly, added new parameter \(\alpha \) in Mann orbit works as control variable that increases the stability performance of the traffic model.     

Using modified Mach-Zehnder interferometer to get better nonlinear correction term of an isotropic nonlinear material

Nonlinear materials have been well established as photo refractive switching material. Important applica- tions of isotropic nonlinear materials are seen in self-focusing, defocusing phenomena, switching systems, etc. The nonlinear correction term is basically responsible for the optical switches. Mach-Zehnder inter- ferometer （MZI） is a well-known arrangement for determining the above correction term, but there are some major problems for finding out the term by MZI. We propose a new method of finding the nonlinear correction term as well as the second order nonlinear susceptibility of the materials by using a modified MZI system. This method may be used to find out the above parameters for any unknown nonlinear material.     

Microstructure and properties of spark plasma sintered Fe–Cr–Mo–Y–B–C bulk metallic glass

Fabrication of Fe-based amorphous alloy using spark plasma sintering (SPS) process has been reported. Fully amorphous compacts with ～95% relative density were successfully sintered at temperature about 100 °C lower than glass transition temperature (T_g: 575 °C). Formation of crystalline Fe₂₃(C, B)₆ phases within near-fully dense (～99%) amorphous matrix is observed at sintering temperatures (>550 °C) close to glass transition temperature. Microstructure evolution in sintered compacts indicated that density, degree of crystallinity, and mechanical properties can be effectively controlled by optimizing SPS parameters.     

Triorganotin(IV) Derivatives of Bidentate Schiff Bases: Synthesis and Spectral Studies

Abstract

Reaction of tri-n-butyl tin(IV) chloride with the sodium salt of Schiff bases [salicylidene-2-aminopyridine (sapH), salicylidene-2-amino-4-picoline (sapicH), salicylidene-2-methyl-1-aminobenzene (o-smabH), salicylidene-4-methyl-1-aminobenzene (p-smabH), salicylidene-1- aminobenzene (sabH), salicylidene-3-nitro-1-aminobenzene (snabH)] in MeOH-C₆H₆ mixture in 1:1 molar ratio produced complexes of the type [Buⁿ ₃Sn(sb)] (where sb = Schiff bases). All complexes obtained were characterized by elemental analysis (C, H, N, and Sn), infrared (IR), nuclear magnetic resonance (NMR; ¹H, ¹³C, and ¹¹⁹Sn), and TOF-MS spectroscopic studies. These complexes were found to be monomeric, colored viscous liquids and are soluble in polar solvents (methanol, ethanol, DMSO, and DMF). On the basis of ¹¹⁹Sn NMR observations, a five coordination geometry around tin(IV) atom in these complexes is proposed tentatively.     

Fabrication of Graphitic Carbon Nitride-Based Film: An Emerged Highly Efficient Catalyst for Direct C-H Arylation under Solar Light

Photoredox C-H bond formation can proceed in aerobic environment under solar light and has therefore become attractive.Nowadays,different types of expensive nov...     

柑桔黄龙病的可见-近红外光谱特征

柑桔黄龙病是一种以木虱为载体的细菌病原,目前还没有行之有效的治疗方法,对世界柑桔产业构成了严重的威胁。探索快速检测柑桔黄龙病的方法,对该病的诊断、评估及进一步的控制都具有重要意义。该研究采用了快速、无损的光谱方法对该病害特征进行初步探索。实验针对健康及染病植株的叶片及冠层,分别在实验室条件及田间环境下测量了其可见-近红外光谱反射率,以分析寻找二者的光谱差异。对原始光谱数据进行了平滑、聚类平均等预处理,并求取了一阶微分以确定其红边位置(red edge position, REP)。为了应对一阶微分在REP处的多个波峰现象,采用了线性外插值法及拉格朗日插值法量化REP。研究结果显示,健康及染病样本的反射率在可见光、近红外具有明显的差异。相比于健康样本,染病样本因其呈现的黄化现象,使其反射率在可见光区较高;又因黄龙病菌会明显阻碍叶片对水分的吸收而使其反射率在近红外较低。REP同样显示了潜在的区分能力,其明显随着染病程度的加深逐渐向红波段移动。在染病程度差异较大的数据集中,REP平均值相差达20 nm;而在染病程度差异较小的数据集中,阈值分割法的分类精度也高达90%以上,且线性外插值法的分类精度略高于拉格朗日插值法。本研究成果为利用光谱技术快速无损检测柑桔黄龙病提供了可靠的理论依据。