Broadband and Tunable-Focus Flat Lens with Dielectric Metasurface

Plasmonics - Metasurface-based flat lens have great potentials for applications in compact and portable cameras. However, the properties of optical metasurfaces are strongly limited by the...     

Improving Efficiency and Birefringence of an All-Dielectric Metasurface Quarter-Wave Plate Using Graphene

Plasmonics - Conventional all-dielectric metasurfaces show remarkable properties including high efficiency and tunability of the optical response. However, extreme narrow bandwidth is a limitation...     

Tailoring Active Far-Infrared Resonator with Graphene Metasurface and Its Complementary

Far-infrared part of electromagnetic spectrum and its technological details have been highly sought after due to its myriad applications including imaging, spectroscopy, industry control, and communication. However, lack of efficient components of electronic and photonic sources/detectors working in this particular spectrum has impeded its widespread application. One of the bottlenecks lies in the compact far-infrared polarization-sensitive resonator/modulator in compatible with pixel-detector for far-infrared spectroscopy. In this work, we demonstrate strong electric resonance response in perforated graphene sheet at this particular electromagnetic region. The results demonstrate inherently different natures for the strong electromagnetic response between graphene-based and metallic metamaterials. Unlike the metallic metamaterials relying on the geometrical inductance for magnetic response, the electric resonance caused by localized dipole/multipolar modes is found to be dominated in graphene and thus enabling sub-wavelength confinement of electromagnetic field. The Babinet’s principle is proposed to be applied for broadband far-infrared modulation and resonant filters design of graphene-based metamaterial. The active tunable electric resonance through electrostatic doping on the graphene-based patterns provides efficient route for compact biosensing, far-infrared imaging, and detection.     

Gold Cone Metasurface MIC Sensor with Monolayer of Graphene and Multilayer of Graphite

Plasmonics - This report makes a comparison between the spectrum features of plasmonic metamaterial metal-insulator-conductor (MIC) sensor with a monolayer of graphene and another MIC sensor with a...     

Linear-to-Circular Polarization Converter with Adjustable Bandwidth Realized by the Graphene Transmissive Metasurface

Plasmonics - A tunable linear-to-circular polarization converter (LTCPC) for the terahertz (THz) regime which consists of two conductive layers and a graphene transmissive metasurface layer...     

Steering of Guided Light with Graphene Metasurface for Refractive Index Sensing with High Figure of Merits

The steering of guided light in surface plasmon resonance (SPR) sensing platforms introduced more than eight decades ago from the first proposed optical sensor in 1983. However, sensing the environmental variation considering transverse modes is still require the attention from the scientist. Here, for the first time, by considering steering of guided light a high-performance SPR sensor base on Otto structure is proposed. By incorporating the graphene and white graphene in to a prism-waveguide configuration, we calculated the excitation of both TE(TM) modes as refractive index is changed from 1 to 1.04. to analysis of the structure finite-difference time-domain (FDTD) is applied. To benchmark of the structure performance parameters including sensitivity, figure of merit, polarization extinction ratio (PER), and insertion loss (IL) are calculated. Numerical results show that maximum sensitivity and figure of merit are obtained for TM modes of 1226 and 27 respectively. In such a case, graphene monolayer is applied. By considering coupling condition, at the μc?=?0.4 eV, the maximum value of PER is 75 dB, and IL is 0.022 dB. Moreover, it is obtained that in all these conditions PER is higher than 8 dB, and IL is less than 0.04 dB.

     

Dielectric Spectroscopy: a Rapid Method for the Determination of Solvent Biocompatibility During Biotransformations

Dielectric spectroscopy provides a convenient means of determining the degree of intactness of biological cells. 4-terminal dielectric measurements of suspensions of Saccharomyces cerevisiae at 0.4 MHz show that, as with all other biological cells, these organisms possess a substantial β-dispersion. The additional of octanol to such suspensions causes a rapid decrease in the electrical capacitance of the suspension, which parallels the cellular viability as determined by methylene blue staining. The kinetics of cell death are determined in part by the rate of dissolution of the organic solvent in the aqueous phase. The toxicity of several organic solvents to S. cerevisiae is studied using this technique, and is found to be dependent upon the polarity of the solvent. The present method provides a simple and rapid means for assessing the biocompatibility of solvents used in biotransformations.     

一种快速、无损大豆种子DNA提取方法的建立和应用

基因分型是进行植物基因功能的遗传分析和分子标记辅助育种的重要环节。该研究以大豆(Glycine max)成熟种子为材料, 建立了通过钻孔采集样品、快速提取DNA进行基因型鉴定的方法。用此方法, 一个熟练的工作人员可以在1个小时内完成120个样品的采集和DNA提取; 同时种子钻孔取样后, 不会对大豆种子的萌发造成影响。利用该方法获得的DNA可满足PCR扩增的要求。实验重复性好, 成功率在98%以上。这种快速且无损的大豆种子基因型鉴定方法可以用于鉴定杂交种子、品种纯度以及遗传分析等研究工作。     

Rapid Prototyping of a High Sensitivity Graphene Based Glucose Sensor Strip

A rapid prototyping of an inexpensive, disposable graphene and copper nanocomposite sensor strip using polymeric flexible substrate for highly sensitive and selective nonenzymatic glucose detection has been developed and tested for direct oxidization of glucose. The CuNPs were electrochemically deposited on to the graphene sheets to improve electron transfer rates and to enhance electrocatalytic activity toward glucose. The graphene based electrode with CuNPs demonstrated a high degree of sensitivity (1101.3±56 μA/mM.cm²), excellent selectivity (without an interference with Ascorbic Acid, Uric Acid, Dopamine, and Acetaminophen), good stability with a linear response to glucose ranging from 0.1 mM to 0.6 mM concentration, and detection limits of 0.025 mM to 0.9 mM. Characterization of the electrodes was performed by scanning electron microscopy (FESEM and SEM). The electrochemical properties of the modified graphene electrodes were inspected by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry.     

Tunable Properties of Surface Plasmon Resonances: The Influence of Core–Shell Thickness and Dielectric Environment

In the present study, we have investigated the extinction spectra of coated sphere (using dipole model) with different core–shell radius, in which the core is TiO₂ and the shell is made up of silver or gold nanoparticles. Nanoparticles exhibit surface plasmon resonance peak; these plasmonic peaks are highly tunable in wavelength range of 300 to 1,100 nm; in fact, the blue and red shifting of resonance peak highly depends on the core–shell thickness. The broadness of resonance peaks are analysed in terms of full width at half maxima (FWHM), and the width of these resonance peaks is also the function of core–shell radius.     

Multi-Band High Refractive Index Susceptibility of Plasmonic Structures with Network-Type Metasurface

Plasmonics - We theoretically propose a simple plasmonic structure with network-type metasurface consisting of double-layer metal-dielectric network-type metasurface on the two-layer dielectric...     

Rapid Determination of Cytokinins and Auxin in Cyanobacteria

Five cyanobacterial strains, Anabaena sp. Ck1, Oscillatoria sp. Ck2, Phormidium sp. Ck3, Chroococcidiopsis sp. Ck4, and Synechosystis sp. Ck5 were selected for their positive cytokinins-like activity using cucumber cotyledon bioassay and GUS assay in Arabidopsis ARR5::GUS. Classical cucumber cotyledon bioassay was modified for direct screening of cyanobacteria avoiding need for extraction and purification. Cytokinins from cyanobacteria were absorbed onto filter paper which was then assayed for cytokinins-like activity. A rapid chromatographic method was developed for the simultaneous determination of cytokinins and indole-3-acetic acid (IAA). Cyanobacterial biomass (50–100 mg) and cell-free culture filtrate were extracted in Bieleski buffer and purified by solid-phase extraction. The extract was used to determine phytohormones by ultra performance liquid chromatography and electrospray ionization-tandem mass spectrometry in positive and negative modes, respectively, with multiple reactions monitoring. Stable isotope-labeled cytokinins and IAA standards were added in the samples to follow recovery of the compounds and method validation. Five cytokinins determined in the selected strains were Zeatin (cis and trans isomers), Zeatin riboside, Dihydrozeatin riboside, and zeatin-o-glucoside. The strains were shown to accumulate as well as release the phytohormones.     

重金属残留的快速检测

环境及农畜产品中的重金属残留已对人类安全构成严重威胁,急需快速、高效的重金属残留检测方法。该文总结了国内外有关采用生物、化学传感器、免疫学方法等快速检测环境及农畜产品中重金属残留的研究进展,并对其发展前景及市场化作了预测及展望。     

Interferometric Control of Signal Light Intensity by Anomalous Refraction with Plasmonic Metasurface

We propose a new method of controlling signal light intensity by changing the polarization direction of pump light that is incident on a phase-gradient metasurface. Theoretical analyses and simulations demonstrate that, when the incident angles for signal and pump light sources conform to a certain relationship, the anomalous refraction of the pump light superposes with the signal light. The intensity of the signal light can be fully tuned across a broadband range by varying the polarization direction of the pump light. Our methods will contribute to the development of promising techniques to be used in photonics devices such as amplitude modulators and photoswitches.     

Rapid optical control of nociception with an ion-channel photoswitch

Local anesthetics effectively suppress pain sensation, but most of these compounds act nonselectively, inhibiting activity of all neurons. Moreover, their actions abate slowly, preventing precise spatial and temporal control of nociception. We developed a photoisomerizable molecule, quaternary ammonium-azobenzene-quaternary ammonium (QAQ), that enables rapid and selective optical control of nociception. QAQ is membrane-impermeant and has no effect on most cells, but it infiltrates pain-sensing neurons through endogenous ion channels that are activated by noxious stimuli, primarily TRPV1. After QAQ accumulates intracellularly, it blocks voltage-gated ion channels in the trans form but not the cis form. QAQ enables reversible optical silencing of mouse nociceptive neuron firing without exogenous gene expression and can serve as a light-sensitive analgesic in rats in vivo. Because intracellular QAQ accumulation is a consequence of nociceptive ion-channel activity, QAQ-mediated photosensitization is a platform for understanding signaling mechanisms in acute and chronic pain.     

Cadmium for all meals – plants with an unusual appetite

Since the beginning of the Bronze Age the acquisition of metals and the mastering of metal processing has been a driving force in human civilisation. It is difficult to imagine, however, how a plant could possibly profit from accumulating excessive amounts of a metal for which there is no metabolic need. Leaving behind an environmentally degraded wasteland, human mining and smeltering activities contributed to providing the niches for such plants, sometimes even accomplishing seed dispersal – through seeds attached to the boots of migrating miners. A stunning example of this is found in the healthy populations of Thlaspi caerulescens in the Cevennes (southern France), the leaves of which have been found to contain the toxic and non-essential metal cadmium (Cd) at concentrations between 1000 and 3000 mg kg⁻¹ dry biomass (R. D. Reeves, unpublished). In this issue, experiments under controlled experimental and glasshouse conditions are reported, confirming an extraordinary level of Cd accumulation and tolerance in these populations (Lombi et al ., pp. 11–20).     

Rapid and high resolution genotyping of all Escherichia coli serotypes using 10 genomic repeat-containing loci

Our laboratory has previously published two multiple-locus variable-number tandem-repeats analysis (MLVA) methods for rapid genotyping of Escherichia coli (E. coli), which are now in routine use for surveillance and outbreak detection. The first assay developed was specific for E. coli O157:H7; however this assay was not suitable for genotyping other E. coli serotypes. A new generic MLVA-assay was then developed with the capability of genotyping all E. coli serotypes. This generic E. coli MLVA (GECM7) was based on polymorphism in seven variable number of tandem repeats (VNTR) loci. GECM7 worked well with the majority of E. coli serotypes; however we wanted to increase the resolution for this method based in part of comparison with PFGE typing of E. coli O26:H11, where PFGE appeared to display higher resolution. The GECM7 method was improved by adding three new repeat-loci to a total of ten (GECM10), and a considerable increase in resolution was observed (from 296 to 507 genotypes on the same set of strains).     

Singular Integral Equations in Scattering of Planar Dielectric Waveguide Eigenwaves by the System of Graphene Strips at THz

Plasmonics - We consider the scattering of the H-polarized eigenwaves of a planar dielectric waveguide by a coplanar system of graphene strips in the THz range. The strips are placed along the...     

利用厚度剪切模传感器在线快速检测鼠伤寒沙门氏菌

鼠伤寒沙门氏菌的浓度和生长用厚度剪切模（ＴＳＭ）传感器在线进行了测定．通过实验发现该法简单、实时和快速．该传感器的响应和细胞浓度之间存在良好的线性关系,相关系数为０．９７４．细菌的生长初始期即延滞期和对数生长期可以用该装置在线测定．影响测定的诸因素也进行了讨论,如培养基和电解质是关键的因素．测定的最佳浓度范围为１．２５×１０５～１×１０１０细胞／升．     

血清游离精氨酸的快速检测

建立快速、准确的精氨酸定量检测方法。采用 6 30 0黄金系统氨基酸分析仪 ,在锂柱生理体液分析方法基础上 ,建立血清游离精氨酸 (ARG)快速测定方法。血清样本经磺基水杨酸沉淀蛋白后取上清液进行色谱分析 ,色谱柱为Beckman公司阳离子交换柱 (12cm× 4 .0mm) ;流动相为 2 0mmol·L- 1 柠檬酸锂水溶液 ,流速为 2 0ml·h- 1 ;比色波长 5 70nm。该法检测精氨酸浓度的线性范围为 5mg·L- 1 ～ 5 0mg·L- 1 ,相关系数 0 .99834,最低检测限 1mg·L- 1 ,重复性 :日内RSD 0 .4 0 % ,日间RSD 0 .5 5 % ,回收率 97.6 7%～ 10 0 .6 7% (平均值 99.0 7% ) ;整个实验过程耗时 2 8min。该法简便、快速、准确、可靠 ,适用于临床和科研工作。