Constrained differential evolution with multiobjective sorting mutation operators for constrained optimization

Differential evolution (DE) is a simple and powerful evolutionary algorithm for global optimization. DE with constraint handling techniques, named constrained differential evolution (CDE), can be used to solve constrained optimization problems (COPs). In existing CDEs, the parents are randomly selected from the current population to produce trial vectors. However, individuals with fitness and diversity information should have more chances to be selected. This study proposes a new CDE framework that uses nondominated sorting mutation operator based on fitness and diversity information, named MS-CDE. In MS-CDE, firstly, the fitness of each individual in the population is calculated according to the current population situation. Secondly, individuals in the current population are ranked according to their fitness and diversity contribution. Lastly, parents in the mutation operators are selected in proportion to their rankings based on fitness and diversity. Thus, promising individuals with better fitness and diversity are more likely to be selected as parents. The MS-CDE framework can be applied to most CDE variants. In this study, the framework is applied to two popular representative CDE variants, (μ + λ)-CDE and ECHT-DE. Experiment results on 24 benchmark functions from CEC’2006 and 18 benchmark functions from CEC’2010 show that the proposed framework is an effective approach to enhance the performance of CDE algorithms.     

Efficient framework for mobile walkthrough application

The past few years have witnessed a dramatic growth in the number and variety of graphics intensive mobile applications, which allow users to interact and navigate through large scenes such as historical sites, museums and virtual cities. These applications support many clients and impose a heavy requirement on network resources and computational resources. One key issue in the design of cost efficient mobile walkthrough applications is the data transmission between servers and mobile client devices. In this paper, we propose an effective progressive mesh transmission framework that stores and divide scene objects into different resolutions. In this approach, each mobile device progressively receives and processes only the object’s details matching its display resolution which improves the overall system’s response time and the user’s perception. A fine grained cache mechanism is used to keep the most frequently requested objects’ details in the device memory and consequently reduce the network traffic. Experiments, in simulated and real world environment, are used to illustrate the effectiveness of the proposed framework under various settings of the virtual scene and mobile device configuration. Experimental results show that the proposed framework can improve the walkthrough system performance in mobile devices, with a relatively small overhead.     

Complexes with pyrazine-tetrathiafulvalene-dithiolate (pztdt) ligand [M(pztdt)2], M = Ni,Pd, Pt; Synthesis and characterisation

The synthesis and characterisation of three metal bisdithiolene complexes based on the recently reported highly extended ligand incorporating fused tetrathiafulvalene and pyrazine moieties, [M(pztdt)₂], M = Ni, Pd, Pt and pztdt = pyrazinetetrathiafulvalenedithiolate, are reported. These complexes were obtained under anaerobic conditions as crystals of dianionic tetrabutylammonium salts. The crystal structures of Ni and Pd complexes as determined by single crystal X-ray diffraction confirm the ability of these molecules to established interactions with their neighbours through the pyrazine moieties. These dianionic complexes easily undergo oxidations to their monoanionic and neutral states, with a narrow range of stability for the monoanionic and an extended one for the neutral forms that is rather insoluble in common solvents.     

A fluorescence chemosensor for benzonitrile derived from in-situ synthesis of azolate–carboxylic acid and zinc(II) ions

A new zinc(II) homometallic coordination polymer (CP), {[Zn(TAA-OH)₂] · 1.5H₂O}_n (1) (HTAA-OH = 2-(5-hydroxy-1H-1,2,4-triazole-1-yl) acetic acid) has been synthesized via an in-situ synthetic approach and structurally characterized in detail. In 1, the HTAA-OH ligand is generated in-situ by the nucleophilic addition of 2-(1H-1,2,4-triazole-1-yl) acetic acid. CP 1 features a 2D structure with sql topology, where the neighboring Zn(II) ions are bridged through two oxygen atoms of carboxyl group and two nitrogen atoms of triazole from the HTAA-OH ligands. Luminescence study shows that 1 dispersed in acetonitrile performs a distinct luminescence enhancing effect upon addition of benzonitrile, indicating that 1 is a promising fluorescence chemosensor for benzonitrile.     

Comparative in vivo toxicity,organ biodistribution and immune response of pristine,carboxylated and PEGylated few-layer graphene sheets in Swiss albino mice: A three month study

We present a comprehensive 3 month report on the acute and chronic toxicity of intravenously administered (20 mg kg⁻¹) few-layer graphene (FLG) and, its carboxylated (FLG-COOH) and PEGylated (FLG-PEG) derivatives in Swiss albino mice. Whole-animal in vivo tracking studies revealed that irrespective of surface modifications, graphene predominantly accumulated in lungs over a period of 24 h. Histological assessment and ex vivo confocal Raman spectral mapping revealed highest uptake and retention in lung tissue, followed by spleen, liver and kidney, with no accumulation in brain, heart or testis. FLG and FLG-COOH accumulated within organs induced significant cellular and structural damages to lungs, liver, spleen, and kidney, ranging from mild congestion to necrosis, fibrosis and glomerular filtration dysfunction, without appreciable clearance. Serum biochemistry analysis revealed that both FLG and FLG-COOH induced elevated levels of hepatic and renal injury markers. Quantitative RT-PCR studies conducted on 23 critical inflammation and immune response markers showed major alterations in gene expression profile by FLG, FLG-COOH and FLG-PEG treated animals. FLG-PEG in spite of its persistance within liver and spleen tissue for 3 months, did not induce any noticeable toxicity or organ damage, and displayed significant changes in Raman spectra, indicative of their biodegradation potential.     

Ultrathin graphitic carbon nitride nanosheets and graphene composite material as high-performance PtRu catalyst support for methanol electro-oxidation

Graphitic carbon nitride (g-C₃N₄) has been demonstrated as an advanced support material for Pt nanoparticles (NPs) due to its excellent stability and abundant Lewis acid for anchoring metal NPs. However, its non-conductive nature and low surface areas still impede its application in electrochemical fields. Herein, a π–π stacking method is presented to prepare graphene/ultrathin g-C₃N₄ nanosheets composite support for PtRu catalyst. The weaknesses of g-C₃N₄ are greatly overcome by establishing a 2D layered structure. The significantly enhanced performance for this novel PtRu catalyst is ascribed to reasons as follows: the homogeneous dispersion of PtRu NPs on g-C₃N₄ nanosheets due to its abundant Lewis acid sites for anchoring PtRu NPs; the excellent mechanical resistance and stability of g-C₃N₄ nanosheets in acidic and oxidative environments; the increased electron conductivity of support by forming a layered structure and the strong metal-support interaction (SMSI) between metal NPs and g-C₃N₄ NS.     

基于CapsNet的汉字字形表征模型

提出基于胶囊神经网络(CapsNet)的汉字字形表征模型,通过表征汉字字形中的部件实现汉字字形的表征.首先,对任一汉字字形生成所有部件类别的表征向量.然后,根据部件存在概率,利用基于欧氏距离的离群点检测,选取相应的部件表征向量.最后,由选出的部件表征向量组成该汉字的字形表征.实验表明,文中模型在仅经过部件字形训练的情况下,即可有效识别汉字部件,同时自动生成汉字字形的有效表征.     

Deep-blue thermally activated delayed fluorescence emitter with a very high fluorescence rate

Conventional thermally activated delayed fluorescence (TADF) molecules achieve small energy differences between the lowest singlet and triplet excited states (ΔE_ST) by enhancing the intramolecular charge transfer, which inevitably leads to a wide emission spectrum and low fluorescence rate. Here, we prepared a deep blue TADF molecule via a small ΔE_ST pyridine-phenol fluoroboron complex as the acceptor. The small ΔE_ST is maintained when carbazole donors are attached to the 4-position of the phenyl rings in the fluoroboron complex. Benefiting from the strong electron coupling between the donor (D) and acceptor (A) moieties, the compound Cz-4-BF exhibits a high fluorescence rate of 4.8 × 10⁸ s⁻¹ and a small D-A dihedral angle change in the excited state. Consequently, a photoluminescence (PL) quantum yield of nearly 100% and a PL spectrum with full-width at half-maximum (FWHM) < 60 nm were obtained in solution and low-concentration doped films. A TADF-sensitized fluorescence (TSF) device containing Cz-4-BF achieves an external quantum efficiency of 21%, which is higher than the devices employing classical fluorescent emitters and multiple resonance-type TADF emitters. The Cz-4-BF-based TSF device shows significantly improved color coordinates of (0.14, 0.10) versus a control device without Cz-4-BF.