Electrically switchable two-dimensional photonic crystals made of?polymer-dispersed liquid crystals based on?the?Talbot?self-imaging effect

Electrically switchable two-dimensional photonic crystals were demonstrated using polymer-dispersed liquid crystal materials based on the Talbot self-imaging effect of a single photomask. With the photomask subjected to a collimated Ar⁺ laser beam operating at 488 nm, a three-dimensional spatial light intensity pattern was created due to the Talbot self-imaging effect. The spatial light intensity pattern was then recorded inside a cell filled with the liquid crystal/prepolymer mixture to create photonic crystal structures. The surface morphology of the photonic crystals was examined by an atomic force microscopy. It showed square structures with a lattice constant of ∼0.9 μm. The diffraction and electro-optical properties were also presented. This approach shows a simple and fast fabrication.     

Synthesis and mesomorphic evaluation of new calamitic liquid crystals containing benzothiazole core

The design and synthesis of new calamitic benzothiazole-based liquid crystals,2-[4-（4-alkyloxybenzoyloxy）-phenyl]ben-zothiazoles are presented.The target compound was characterized using spectroscopic techniques,such as FT-IR,NMR(¹H and ¹³C),microanalysis and EI-MS.The liquid crystalline behaviours of these compounds were thoroughly examined by differential scanning calorimetry and polarizing optical microscope techniques.These materials exhibited enantiotropic nematic phase with high thermal stability（>168℃）.Smectic A phase starts to emerge as monotropic（metastable） phase from C10 member and changes into enantiotropic（stable） phase from C12 and persists up to C16 members.     

Surface plasmon resonance in superperiodic metal nanoslits

A superperiodic metal nanoslits device is a surface plasmon resonance optical diffraction grating in which each line of the grating consists of an array of finite number metal nanoslits. The metal nanoslits, upon optical excitations, support localized surface plasmon resonance. The superperiod of the nanoslits causes the coherent radiation of the surface plasmon resonance into the far field with angular dispersion. Therefore, localized surface plasmon resonance in the metal nanoslits can be measured with a CCD or a linear photodetector array. In this Letter, we describe a surface plasmon resonance spectral sensor using a superperiodic gold nanoslits array without using an external optical spectrometer.     

Emerging nanosensor platforms and machine learning strategies toward rapid,point-of-need small-molecule metabolite detection and monitoring

Speedy, point-of-need detection and monitoring of small-molecule metabolites are vital across diverse applications ranging from biomedicine to agri-food and environmental surveillance. Nanomaterial-based sensor (nanosensor) platforms are rapidly emerging as excellent candidates for versatile and ultrasensitive detection owing to their highly configurable optical, electrical and electrochemical properties, fast readout, as well as portability and ease of use. To translate nanosensor technologies for real-world applications, key challenges to overcome include ultralow analyte concentration down to ppb or nM levels, complex sample matrices with numerous interfering species, difficulty in differentiating isomers and structural analogues, as well as complex, multidimensional datasets of high sample variability. In this Perspective, we focus on contemporary and emerging strategies to address the aforementioned challenges and enhance nanosensor detection performance in terms of sensitivity, selectivity and multiplexing capability. We outline 3 main concepts: (1) customization of designer nanosensor platform configurations via chemical- and physical-based modification strategies, (2) development of hybrid techniques including multimodal and hyphenated techniques, and (3) synergistic use of machine learning such as clustering, classification and regression algorithms for data exploration and predictions. These concepts can be further integrated as multifaceted strategies to further boost nanosensor performances. Finally, we present a critical outlook that explores future opportunities toward the design of next-generation nanosensor platforms for rapid, point-of-need detection of various small-molecule metabolites.

Overview of the current status on emerging, multi-faceted nanosensor platform designs and data analysis strategies for rapid, point-of-need detection and monitoring of small-molecule metabolites.     

Size prediction of κ-carrageenan droplets formed in co-flowing immiscible liquid

The formation of κ-carrageenan droplets in channel emulsification was experimentally investigated. The dispersed phase was vertically injected into co-flowing immiscible palm oil in the direction of gravity. This study focused on predicting κ-carrageenan drop size using force balance analysis. The force balance model considers the interfacial tension to be the solitary attaching force, while a combination of the drag force from the co-flowing palm oil and the body force of the extruding κ-carrageenan liquid act as the detaching forces. The conventional model gave poor predictions for droplet size, with an average relative deviation of 23%. This large deviation could be attributed to necking phenomena and an underestimation of the drag force generated on the shear-thinning κ-carrageenan solution. By incorporating correction factors, the average relative deviation of the force balance model dropped to 4%.     

Numerical study of the DLC film flow field in the ECR-PECVD reaction chamber

This paper mainly investigates the optimum parameters for the fabrication of uniform diamond-like carbon (DLC) films on the electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) reaction chamber by analyzing the effect of the reacting gas velocity on the film properties. This work makes use of computational fluid dynamics (CFD) approach to model surface chemical reactions, flow and temperature fields, as well as heat and mass transfer phenomena. The simulation has shown that natural convection and mass transfer affect the recirculating flow within the reactor and, therefore, the distribution of material deposition. In other words, as a result of attaching an endplate (baffle) at the top of the substrate, the deposition rate of the substrate is appreciably enhanced. However, the surface uniformity of the substrate is obviously deteriorated.     

Controlled polymerizations of 2‐(dialkylamino)ethyl methacrylates and their block copolymers in protic solvents at ambient temperature via ATRP

Very well‐controlled polymerizations of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and 2‐(diethylamino)ethyl methacrylate (DEAEMA) in aqueous and methanolic solutions via atom transfer radical polymerization (ATRP) at ambient temperature were demonstrated. Poly(DMAEMA) and poly(DEAEMA) of low polydispersity index (PDI) of ～1.07 were obtained using the p‐toluenesulfonyl chloride/CuCl/1,1,4,7,10,10‐hexamethyl‐triethylenetetramine (p‐TsCl/CuCl/HMTETA) system. Excellent control of polymerization was achieved even in pure methanol. This is in contrast with the very poor control of DMAEMA ATRP in methanol reported previously using a different intiator/catalyst/ligand system. The initiator p‐TsCl underwent hydrolysis reaction in aqueous methanolic solutions with a second‐order rate constant of 6.1 × 10^?4 dm³ mol^?1 s^?1 at 25 °C. Both poly(DMAEMA) and poly(DEAEMA) retained almost full chlorine‐functionization at the chain ends. Well‐defined block copolymers of DEAEMA and DMAEMA were successfully obtained by starting with either macroinitiators of DEAEMA or DMAEMA. Other well‐defined diblock copolymers could be prepared using these macroinitiators. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5161–5169, 2004     

Visualization of transient natural convection heat transfer from a vertical rectangular fin

Experiments on thermal visualization of transient natural convection from short vertical rectangular fins were conducted using the technique of laser holographic interferometry. A sequence of infinite-fringe interferograms recorded for the heating regime of an aluminum fin demonstrates the effect of fin base heating on local convection coefficients and reveals alternating and oscillatory buoyancydriven flows similar to those over the top surface of heated horizontal plates. The effect of fin base heating results in greater uniformity of the local heat transfer coefficient along the fin. It also significantly reduces the steady-state heat transfer coefficients of short vertical fins compared to their transient values. Hence, the use of steady-state solutions for the design of short vertical fins operating in transient conditions may not introduce as much error as was previously thought.     

A Simple Analytical and Numerical Approach for Pricing Compound Options

A compound option is simply an option on an option. In this short paper, by using a martingale technique, we obtain an analytical formula for pricing compound European call options. Numerical results are given to explain some economic phenomenon.