A general stability result for the semilinear viscoelastic wave model under localized effects

Our main goal in the present work is to address an integro-differential model under localized viscoelastic and frictional effects arising in the Boltzmann theory of viscoelasticity. More precisely, we consider a general version in the history context of the pioneer localized viscoelastic problem approached by Cavalcanti and Oquendo (2003) in the null history scenario, and more recently by Cavalcanti et al. (2018) in the history framework. By means of a new observability inequality, we prove a general stability result to the model under a weaker assumption on the localized frictional damping and a slower condition on the decreasing memory kernel (of polynomial type) than the previously mentioned works. To achieve such stability results, we still work in a general setting by removing the assumption on complementary damping mechanisms and show, in some reasonable situations concerning the density coefficient, that the localized viscoelastic effect is enough to ensure the general stability (of polynomial type) to the problem.     

Plasmon-Enhanced Electrochemiluminescence at the Single-Nanoparticle Level

Plasmon-enhanced electrochemiluminescence (ECL) at the single-nanoparticle (NP) level was investigated by ECL microscopy. The Au NPs were assembled into an ordered array, providing a high-throughput platform that can easily locate each NP in sequential characterizations. A strong dependence of ECL intensity on Au NP configurations was observed. We demonstrate for the first time that at the single-particle level, the ECL of Ru(bpy)₃²⁺-TPrA was majorly quenched by small Au NPs (<40 nm), while enhanced by large Au ones (>80 nm) due to the localized surface plasmon resonance (LSPR). Notably, the ECL intensity was further increased by the coupling effect of neighboring Au NPs. Finite Difference Time Domain (FDTD) simulations conformed well with the experimental results. This plasmon enhanced ECL microscopy for arrayed single NPs provides a reliable tool for screening electrocatalytic activity at a single particle.     

Rapid synthesis of bovine serum albumin-conjugated gold nanoparticles using pulsed laser ablation and their anticancer activity on hela cells

Nanoscience research aims to produce nanoparticles without adverse effects for medical applications. The pulsed laser ablation (PLA) technique was utilized in this study to synthesize gold nanoparticles (AuNPs) using bovine serum albumin (BSA) in simulated body fluid (SBF) at the fundamental wavelength of the Nd: YAG laser (1064 nm). BSA acted as a stabilizer, reducing and capping agent to produce spherically shaped AuNPs (diameter 3–10 nm). The successful synthesis of AuNPs was confirmed through color changes and UV–vis spectroscopy. The agglomeration and precipitation of AuNPs are attributed to the presence of BSA in the solution, and electrostatic repulsion interactions between BSA and Au nanoclusters. The effect of salt concentration of SBF on BSA stability as well as the interaction of BSA conjugated AuNPs to form complexes was studied using molecular dynamic simulations. Our results show that the stability of AuNPs-BSA conjugates increase with the salt concentration of BSA. Moreover, the synthesized AuNPs exhibit low toxicity and high biocompatibility, supporting their application in drug delivery. Investigation of the cytotoxic effect of the synthesized AuNPs show that normal fibroblast cells (L929) remain intact after treatment whereas a dose-dependent inhibition effect on the growth of cervix cancer cells (HeLa) is observed. In general, this study presents an effective, environmentally-friendly, and facile approach to the synthesis of multifunctional AuNPs using the PLA technique, as a promising efficacious therapeutic treatment of cervical cancer.     

Detection of antinuclear antibodies by a colloidal gold modified optical fiber: comparison with ELISA

A fiberoptic evanescent-wave sensor has been developed for the measurement of antinuclear antibodies in sera from patients and healthy individuals. The sensor was constructed on the basis of modification of the unclad portion of an optical fiber with self-assembled gold colloids, where the colloidal gold surface was further functionalized with extractable nuclear antigens. Results show that detection of antinuclear antibodies by this sensor agrees quantitatively with the clinically accepted enzyme-linked immunosorbent assay (ELISA) method. This sensing platform has the following advantages: label-free and real-time detection capability, simple to construct and use, highly sensitive, and does not require a secondary antibody. The sensitivity of this platform is at least an order of magnitude higher than that of the ELISA method and thus may lead to a new direction in recognition of immune response. Biomolecular binding of antinuclear antibodies (ANA) with extractable nuclear antigens (ENA)-functionalized gold nanoparticles results in a change of surface plasmon absorption. When light propagates in an optical fiber by multiple total internal reflection, such a change in signal can be significantly enhanced.     

The basic principle of radioluminescence dating and a localized transition model

The IR signal of the radioluminescence of potassium feldspars is caused by the luminescent transition of electrons into optically active traps. This allows the direct determination of the density of trapped electrons and therefore a method of sediment dating with higher precision and accuracy than conventional luminescence dating. The principle behind it and its advantages are presented, in particular the fact that it is a real single aliquot dating technique. The explanation of both radioluminescence and IR-optically stimulated luminescence (IR-OSL) in terms of a band model is possible after the introduction of a localized transition. In contrast to previous models, the process of dose accumulation in the sediment was simulated using a dose rate as low as in real sediments. Preheat experiments indicate that the recombination centres are the unstable part of the luminescence process. The parameters of these centres are equal to those previously assigned to thermally unstable electron traps. Furthermore, the sources of systematic errors in conventional IR-OSL dating are discussed.     

UNIQUE CONTINUATION ON A HYPERPLANE FOR WAVE EQUATION

51.IntroductionTheuniquecontinuationisthat,ifasolutionofapartialdifferentialequationvanishesinanopenset,thenitmustvanishontheconnectedcomponentwhichcontainsthisopenset.Itiswellunderstoodforellipticoperatorsofthesecondorder.In1939,Carleman[2]showedauniquecontinuationtheoremforsystemsofpartialdifferentia1equationsinthetwodimensionalcasewhosecoefficientsarenotanalytic.Thepowerfu1techniquewhichheproposediscal1edaCaJrlemanestimateandhasplayedacentralroleinthedevelopmentofuIilquecontinuationaJrgum…     

劈裂纳米环多极表面等离激元共振及折射率传感特性分析

研究了在三开口劈裂金属纳米环中,当入射场偏振方向不同时出现的多极局域表面等离激元共振现象及折射率传感特性。研究表明,当入射场偏振方向分别沿x 轴和y 轴时,在可见光-近红外区域分别激发起两个和三个明显的共振峰。通过改变缺口的张角,能够实现对共振峰位和强度的可控调整。共振峰位处劈裂纳米环的近场分布表明,LHA(左半弧)和DRHA(双右半弧)之间等离激元的杂化耦合是形成上述共振的原因。劈裂纳米环的多极共振非常适合折射率传感应用。当改变周围环境折射率,入射场沿x 轴偏振时,折射率敏感度的最大值可达到1365nm/RIU;入射场沿y 轴偏振时,折射率敏感度最大值可达2229nm/RIU。     

利用矩形金属周期阵列实现局域电场的增强和共振波长的可控

基于表面等离激元共振(SPR)的原理,设计了一种具有矩形凹槽周期阵列微结构的金属增强基底。利用有限元方法对基底表面附近电场的分布进行了理论模拟分析,结果表明在SPR共振情况下,其凹槽微结构坑口处可得到强局域场,局域电场强度E_max／E₀可达20。通过改变结构的周期、凹槽长度l、宽度w以及环境介质,SPR共振峰发生规律性的移动,波长覆盖范围为500～1 000 nm。入射光沿x方向偏振的情况下,随着结构x方向周期P_x的增加,SPR共振峰明显红移。当入射光波长与P_x相当时,观察到凹槽内局域电场突然减小的现象。这是由于满足了波矢匹配条件,传播型SPP被激发导致的。改变凹槽长度l,发现共振波长随l的增加红移,近似呈线性关系。环境介质折射率的增加也会引起共振峰的红移。而凹槽宽度w的增加将导致其蓝移。这种规律性的移动为实现共振波长的调控提供了途径。受Jain研究报道的启发,矩形凹槽结构可以等效为两对偶极耦合模型的组合,从而解释SPR共振峰随结构参数变化而发生的移动。     

Effect of CDW and magnetic interactions on the electrons of the manganite systems

We address a model study which includes the co-existence of the charge density wave (CDW) and ferromagnetic interactions in order to explain the colossal magnetoresistance (CMR) in manganites. The Hamiltonian consists of the ferromagnetic Hund's rule exchange interaction between e_g and t_2g spins, Heisenberg core spin interactions and the CDW interaction present in the e_g band electrons. The core electron magnetization, induced e_g electron magnetization and the CDW gap are calculated using Zubarev's Green's function technique and determined self-consistently. The effect of core electron magnetization and the CDW interaction on the induced magnetization as well as on the occupation number in the different spin states of the e_g band electrons are investigated by varying the model parameters of the system like the CDW coupling, the exchange coupling, the Heisenberg coupling and the external field. It is observed that the induced magnetization exhibits re-entrant behaviour and exists within a narrow temperature range just below the Curie temperature. This unusual behaviour of the e_g band electrons will throw some new insights on the physical properties of the manganite systems.