Liquid‐crystal chiral‐nematic systems with photoinduced helix inversion

Abstract— The induced helical pitch in liquid‐crystalline systems based on 4‐pentyl‐4′‐cyanobiphenyl (5CB) and containing chiral 6‐arylidene derivatives of 3(R)‐methylcyclohexanone has been found to change its sign and to decrease in the absolute value when exposed to the UV irradiation. After the photostationary state is reached, the pitch remains invariable regardless of any consequent light radiation. This state is characterized by a large helical twist which exceeds an initial one in more than three times, thereby making it possible to obtain compositions with the selective reflection of light in the visible spectral region. This phenomenon could be utilized in colour filters for display devices. The effect observed is caused by the effective reversible photochemical E‐Z‐isomerization of the chiral dopant. This was proved by photochemical preparative synthesis of one of the respective Z‐isomers and independent studies of its behaviour in 5CB.     

An architecture for extensible middleware platforms

This article presents a middleware platform architecture whose goals, motivated by the needs of a real‐world application, are the following: separation of functional and non‐functional code in applications, composition of non‐functional properties, and modularity and extensibility of the middleware platform itself. This architecture is inspired by the Enterprise Java Beans platform, and uses a new object composition model to separate and compose the non‐functional properties. In order to evaluate this architecture, we have implemented the JavaPod platform which we have used to implement a prototype of the application that motivated our goals. The results of these experiments show that our goals can indeed be achieved with our architecture. Copyright © 2001 John Wiley & Sons, Ltd.     

Design of a low‐profile broadband antenna with E‐shaped patch cells

This article presents a low‐profile broadband antenna. The E‐shaped metal cells are utilized on the top layer, which is excited by the microstrip line through the coupling slot in the ground plane. The characteristics of the E‐shaped patch cell and antenna are extensively investigated and presented. Dual resonances with close proximity are obtained to realize wideband impedance matching. An attractive feature is found that the bandwidth of the antenna exhibits good correlation with the inductance. The interesting analysis is presented by directly loading inductors to the antenna, and the bandwidth shrinks quickly with larger inductance loaded. Therefore, the antenna proposed in this article has good potential in bandwidth tuning applications. A typical bandwidth from 5.1 to 6.7 GHz is achieved by the fabricated antenna with a maximum measured gain of 10.4 dBi. Meanwhile, the antenna remains a low profile of 0.09 λ _g.     

A photoluminescence-based quantum semiconductor biosensor for rapid in situ detection of Escherichia coli

This work describes a novel method of detecting Escherichia coli using photoluminescence (PL) emission from III–V quantum semiconductor (QS) devices functionalized with two different antibody-based architectures. The first approach employed self-assembled monolayers of biotinylated polyethylene glycol thiols to immobilize biotinylated antibody via neutravidin. In the second approach, we used QS microstructures coated with a thin layer of Si₃N₄ allowing direct functionalization with E. coli antibodies through hydrofluoric acid etching and glutaraldehyde-based reticulation. Atomic force, optical and fluorescence microscopy measurements were used to assess the immobilization process. Depending on the biosensing architecture, density of the immobilized bacteria was observed in the range of 0.5–0.7 bacteria/100 μm². The detection of E. coli at 10⁴ CFU/ml was achieved within less than 120 min of the bacteria exposure. It is expected that an even better sensitivity threshold could be achieved following further optimization of the method.     

Sensing the insulin signaling pathway with an antibody array

The development of insulin resistance and type 2 diabetes is determined by various factors, including defects within the insulin signaling pathway. Mediators of insulin resistance operate through activation of various protein kinase C isoforms, IκB kinase β (IKKβ), and/or c‐Jun N‐terminal kinase, and subsequent inhibition of the proximal insulin signaling pathway via the insulin receptor substrate 1 and Akt. These mechanisms are still largely unresolved because of the complexity of the molecular events. In this study, an expression and activation state profiling of multiple known key signaling biomolecules involved in insulin metabolic and mitogenic signaling pathways was evaluated using a phosphospecific antibody array platform. The results of the arrayed antibodies were verified by the multiplexed bead array assay and conventional Western blot analysis, and confirmed the well‐known inhibitory effects of phorbol esters on insulin signaling pathway activation. Of interest, the increase in protein kinase C signaling responses with phorbol esters was associated with activation of the lipid phosphatase PTEN and a 27 kDa HSP. Thus, this insulin signaling antibody array provides a powerful and effective way to investigate the mechanism of insulin resistance and likely assist the development of innovative therapeutic drugs for type 2 diabetes.     

Rapid differentiation between E. coli and Salmonella Typhimurium using metal oxide sensors integrated with pattern recognition

A rapid method to differentiate between E coli and Salmonella Typhimurium was developed. E. coli and S. Typhimurium were separately grown in super broth and incubated at 37 °C. Super broth without inoculation of E. coli or S. Typhimurium was used as control. Numbers of E. coli and S. Typhimurium were followed using a colony counting method. Identification of the volatile metabolites produced by E. coli and S. Typhimurium was determined using solid-phase microextraction coupled with gas chromatography/mass spectrometry. An electronic nose with 12 non-specific metal oxide sensors was used to monitor the volatile profiles produced by E. coli and S. Typhimurium. Principal component analysis (PCA) and back-propagation neural network (BPNN) were used as pattern recognition tools. PCA was used for data exploration and dimensional reduction. PCA could visualize class separation between sample subgroups. The BPNN was shown to be capable of predicting the number of E. coli and S. Typhimurium. Good prediction was possible as measured by a regression coefficient (R² = 0.96) between true and predicted data. Using metal oxide sensors and pattern recognition techniques, it was possible to discriminate between samples containing E. coli from those containing S. Typhimurium.     

Automated Construction of an Open Reading Frame Library from Sinorhizobium meliloti

An automated, high-throughput, open reading frame (ORF) library construction process has been developed. ORFs from genomic DNA of the microbe Sinorhizobium meliloti were amplified by PCR and cloned into the library vector by homologous recombination instead of traditional ligation. From 960 targets, we successfully generated 723 (75.3%) ORFs from the initial PCR. After cloning the successful samples into the library vector, transforming into E. coli and PCR colony screening, 371 (38.6% overall) ORFs were placed into the new library and sequenced. Our prototype library contained 314 (32.7% overall) clones with sequence identity to the Sinorhizobium meliloti genome.     

Nanorod‐form ZnO‐homojunction ultraviolet light‐emitting diodes

Abstract— Ultraviolet (UV) light‐emitting diodes based on ZnO‐homojunction nanorods is reported. p‐type doping can be obtained from intrinsic (or close to) ZnO by introducing acceptors, such as P or As, using ion implantation followed by appropriate thermal annealing and dopant activation. Our approach provides a possible solution to p‐type doping of ZnO and ZnO‐homojunction light‐emitting diodes. It is interesting to note that this solution is offered in the form of nanorods.     

SERS driven cross-platform based multiplex pathogen detection

We demonstrate a cross-platform approach to simultaneously detect three different pathogens using Raman and UV-vis absorption spectroscopy. Gold (Au), silver (Ag), and Ag-Au core-shell nanoparticles were functionalized with anti-Salmonella typhimurium aptamers, anti-Staphylococcus aureus and anti-Escherichia coli O157:H7 antibodies respectively and labeled with unique Raman reporter molecules. A microfiltration step was used to consolidate a highly selective and specific detection platform, with total detection time under 45 min for both species (E. coli O157:H7 vs. S. typhimurium) and strain (E. coli O157:H7 vs. E. coli K12) level sensing at a limit of a detection ranging between 10² and 10³ CFU/ml. This simple yet robust multiplex detection platform has the potential to be developed into a rapid and portable pathogen sensor for ultrasensitive detection in liquid samples.     

Identifying mortality risk factors amongst acute coronary syndrome patients admitted to Arabian Gulf hospitals using machine‐learning methods

Acute coronary syndrome (ACS) is a leading cause of mortality and morbidity in the Arabian Gulf. In this study, the in‐hospital mortality amongst patients admitted with ACS to Arabian Gulf hospitals is predicted using a comprehensive modelling framework that combines powerful machine‐learning methods such as support‐vector machine (SVM), Naïve Bayes (NB), artificial neural networks (NN), and decision trees (DT). The performance of the machine‐learning methods is compared with that of the performance of a commonly used statistical method, namely, logistic regression (LR). The study follows the current practise of computing mortality risk using risk scores such as the Global Registry of Acute Coronary Events (GRACE) score, which has not been validated for Arabian Gulf patients. Cardiac registry data of 7,000 patients from 65 hospitals located in Arabian Gulf countries are used for the study. This study is unique as it uses a contemporary data analytics framework. A k‐fold (k = 10) cross‐validation is utilized to generate training and validation samples from the GRACE dataset. The machine‐learning‐based predictive models often incur prejudgments for imbalanced training data patterns. To mitigate the data imbalance due to scarce observations for in‐hospital mortalities, we have utilized specialized methods such as random undersampling (RUS) and synthetic minority over sampling technique (SMOTE). A detailed simulation experimentation is carried out to build models with each of the five predictive methods (LR, NN, NB, SVM, and DT) for the each of the three datasets k‐fold subsamples generated. The predictive models are developed under three schemes of the k‐fold samples that include no data imbalance, RUS, and SMOTE. We have implemented an information fusion method rooted in computing weighted impact scores obtain for an individual medical history attributes from each of the predictive models simulated for a collective recommendation based on an impact score specific to a predictor. Finally, we grouped the predictors using fuzzy c‐mean clustering method into three categories, high‐, medium‐, and low‐risk factors for in‐hospital mortality due to ACS. Our study revealed that patients with medical history related to the presences of peripheral artery disease, congestive heart failure, cardiovascular transient ischemic attack valvular disease, and coronary artery bypass grafting amongst others have the most risk for in‐hospital mortality.     

Spectral Processing of Tangential Vector Fields

We propose a framework for the spectral processing of tangential vector fields on surfaces. The basis is a Fourier‐type representation of tangential vector fields that associates frequencies with tangential vector fields. To implement the representation for piecewise constant tangential vector fields on triangle meshes, we introduce a discrete Hodge–Laplace operator that fits conceptually to the prominent cotan discretization of the Laplace–Beltrami operator. Based on the Fourier representation, we introduce schemes for spectral analysis, filtering and compression of tangential vector fields. Moreover, we introduce a spline‐type editor for modelling of tangential vector fields with interpolation constraints for the field itself and its divergence and curl. Using the spectral representation, we propose a numerical scheme that allows for real‐time modelling of tangential vector fields.     

Event‐triggered finite‐time reliable control for nonhomogeneous Markovian jump systems

This article investigates the event‐triggered finite‐time reliable control problem for a class of Markovian jump systems with time‐varying transition probabilities, time‐varying actuator faults, and time‐varying delays. First, a Luenberger observer is constructed to estimate the unmeasured system state. Second, by applying an event‐triggered strategy from observer to controller, the frequency of transmission is reduced. Third, based on linear matrix inequality technique and stochastic finite‐time analysis, event‐triggered observer‐based controllers are designed and sufficient conditions are given, which ensure the finite‐time boundedness of the closed‐loop system in an H_∞ sense. Finally, an example is utilized to show the effectiveness of the proposed controller design approach.     

Robust finite‐time H∞ synchronization for uncertain discrete‐time systems with nonhomogeneous Markovian jump: Observer‐based case

In this article, the problem of robust finite‐time H_∞ synchronization control is investigated for a class of uncertain discrete‐time master‐slave systems with Markovian switching parameters in the observer‐based case. Parameter uncertainties are assumed to be norm‐bounded, and the polyhedral character is utilized to describe the transition probabilities of nonhomogeneous Markov chain. By using stochastic Lyapunov function method and finite‐time analysis techniques, novel sufficient conditions that include the master‐slave parameters are obtained for designing an observer‐based finite‐time H_∞ synchronization control law in terms of linear matrix inequalities. The effectiveness of the proposed theoretical scheme is finally demonstrated by some simulations.     

ADAPTIVE RANKS CLONE AND k‐NEAREST NEIGHBOR LIST–BASED IMMUNE MULTI‐OBJECTIVE OPTIMIZATION

Artificial immune systems (AIS) are computational systems inspired by the principles and processes of the vertebrate immune system. The AIS‐based algorithms typically exploit the immune system's characteristics of learning and adaptability to solve some complicated problems. Although, several AIS‐based algorithms have proposed to solve multi‐objective optimization problems (MOPs), little focus have been placed on the issues that adaptively use the online discovered solutions. Here, we proposed an adaptive selection scheme and an adaptive ranks clone scheme by the online discovered solutions in different ranks. Accordingly, the dynamic information of the online antibody population is efficiently exploited, which is beneficial to the search process. Furthermore, it has been widely approved that one‐off deletion could not obtain excellent diversity in the final population; therefore, a k‐nearest neighbor list (where k is the number of objectives) is established and maintained to eliminate the solutions in the archive population. The k‐nearest neighbors of each antibody are founded and stored in a list memory. Once an antibody with minimal product of k‐nearest neighbors is deleted, the neighborhood relations of the remaining antibodies in the list memory are updated. Finally, the proposed algorithm is tested on 10 well‐known and frequently used multi‐objective problems and two many‐objective problems with 4, 6, and 8 objectives. Compared with five other state‐of‐the‐art multi‐objective algorithms, namely NSGA‐II, SPEA2, IBEA, HYPE, and NNIA, our method achieves comparable results in terms of convergence, diversity metrics, and computational time.     

EO characteristics for a photoaligned VA‐1/4 π cell on a photopolymer layer

The generation of a liquid‐crystal (LC) tilt angle on a copolymer with chalconyl and cholesteryl moiety characteristics was performed, and the electro‐optical (EO) performance of the photoaligned vertical‐alignment (VA) 1/4 π cell by polarized UV exposure on a homeotropic photopolymer surfaces was studied. The LC tilt angles decreased as UV exposure time increased on the copolymer surfaces. A tilt angle of 87° in NLC was observed with an UV exposure of 3 min on the photoalignment‐2 surface. The LC tilt angle is attributed to increased chalcone moiety with increasing UV exposure time. Excellent voltage‐transmittance (V‐T) curves of the photoaligned VA 1/4 π cell by polarized UV exposure on the photopolymer surface for 3 min containing a cholesteryl moiety of 8% were obtained. The V‐T and response‐time characteristics can be improved by the presence of a cholesteryl moiety in the photopolymer.     

New results on stability and L∞‐gain analysis for positive linear differential‐algebraic equations with unbounded time‐varying delays

This article addresses the problems of stability and L_∞‐gain analysis for positive linear differential‐algebraic equations with unbounded time‐varying delays for the first time. First, we consider the stability problem of a class of positive linear differential‐algebraic equations with unbounded time‐varying delays. A new method, which is based on the upper bounding of the state vector by a decreasing function, is presented to analyze the stability of the system. Then, by investigating the monotonicity of state trajectory, the L_∞‐gain for differential‐algebraic systems with unbounded time‐varying delay is characterized. It is shown that the L_∞‐gain for differential‐algebraic systems with unbounded time‐varying delay is also independent of the delays and fully determined by the system matrices. Two numerical examples are given to illustrate the obtained results.     

Observer‐Based H∞ Synchronization Control for Input and Output Time‐Delays Coronary Artery System

The paper investigates the observer‐based H_∞ synchronization for coronary artery time‐delay system under the state immeasurement and external uncertainty. A Luenberger‐like state observer, the observation system, is designed to realize the state reconstruction of the master system. Based on the Lyapunov stability theory and Lyapunov‐Krasovskii functional (LKF), the observer‐based synchronization control condition is derived for a coronary artery system subjected to the external uncertainty bounded by L₂ norm. By introducing the delay‐interval bounds and delay‐derivative limits in LKF, the time‐delays are handled by the delay‐range‐dependent strategy. The tighter upper bound of inequality can be obtained to reduce the conservation by employing further improved result of Jensen inequality and reciprocally convex approach. Furthermore, a decoupling technique is utilized to render the separate and simple controller and observer synthesis condition, which can be further solved by applying the cone complementary linearization approach respectively. Numerical simulations are listed to exhibit the effectiveness of the presented methodology.     

Miniaturization of frequency‐selective rasorber based on 2.5‐D knitted structure

Knitted structure based on through‐silicon vias is utilized to realize the miniaturization of frequency‐selective rasorber (FSR). According to equivalent circuit model analysis, additional inductance and capacitance introduced by an array of metal vias are considered, which is combined with lossy cross‐frame and lossless double square‐loop structure to realize the function of FSR. Through full wave simulation, the proposed 2.5‐D FSR demonstrates one passband between two absorption bands. The simulated results indicate a significant size reduction with P = 0.15 λ_L, where λ_L is the free‐space wavelength at the lowest frequency of ‐10 dB reflection. Moreover, an insertion loss of 0.49 dB can be observed at 3.99 GHz, the fractional bandwidth for reflection coefficients less than ‐10 dB is 100%, and the thickness of the whole structure is 0.138 λ_L, respectively. In addition, the frequency response of this miniaturized FSR is stable for incident angle up to 40° and both linear polarizations. After then, the prototype of this 2.5‐D FSR is fabricated and measured, which shows reasonable agreement with simulated results.     

Protein-induced changes during the maturation process of human dendritic cells: A 2-D DIGE approach

Dendritic cells (DCs) are unique antigen presenting cells, which upon maturation change from a specialized antigen‐capturing cell towards a professional antigen presenting cells. In this study, a 2‐D DIGE analysis of immature and mature DCs was performed, to identify proteins changing in expression upon maturation. The protein expression profile of immature and mature DCs, derived from CD14⁺ peripheral blood monocytes was investigated using two pH ranges (pH 4–7 and 6–9) (n = 4). Ninety one differentially expressed spots (p<0.01) were detected, from which we identified 74 spots (81.32%) corresponding to 41 different proteins. The proteins identified play a role in diverse processes, such as antigen processing/presentation, vesicle transport and cytoskeleton remodeling. In addition, a protein interaction network contained 29 (out of 41) proteins, suggesting that, although they functionally originate from distinct classes, these proteins are acting as a protein‐interactome. In conclusion, the proteins shown here to be altered in expression upon maturation are in line with the morphological and functional changes observed during the maturation process, providing a better understanding of the processes involved. This will open new avenues for investigating treatment regimens for immune‐associated disorders.