Organic Haptics: Intersection of Materials Chemistry and Tactile Perception

The goal of the field of haptics is to create technologies that manipulate the sense of touch. In virtual and augmented reality, haptic devices are for touch what loudspeakers and RGB displays are for hearing and vision. Haptic systems that utilize micromotors or other miniaturized mechanical devices (e.g., for vibration and pneumatic actuation) produce interesting effects, but are quite far from reproducing the feeling of real materials. They are especially deficient in recapitulating surface properties: fine texture, friction, viscoelasticity, tack, and softness. The central argument of this progress report is that in order to reproduce the feel of everyday objects, molecular control must be established over the properties of materials; ultimately, such control will enable the design of materials which can change these properties in real time. Stimuli‐responsive organic materials, such as polymers and composites, are a class of materials which can change their oxidation state, conductivity, shape, and rheological properties, and thus might be useful in future haptic technologies. Moreover, the use of such materials in research on tactile perception could help elucidate the limits of human tactile sensitivity. The work described represents the beginnings of this new area of inquiry, in which the defining approach is the marriage of materials science and psychology.     

Controllability Analysis of Nonlinear Neutral-type Fractional-order Differential Systems with State Delay and Impulsive Effects

International Journal of Control, Automation and Systems - This paper is concerned with the controllability problem of nonlinear neutral-type fractional differential systems with state delay and...     

Fast computational framework for optimal life management of lithium ion batteries

The determination of optimal charging profiles over cycle life of a lithium ion battery is a challenging problem that is extremely important for commercial applications. It is a difficult problem to solve owing to the complex degradation processes occurring inside the battery. Further, modeling of a realistic battery operation, let alone the degradation mechanisms, results in computationally expensive mathematical models. In the present study, a framework is developed towards addressing this problem by (1) developing a method to formulate extremely fast and accurate algebraic models that capture essential features such as charging time and aging characteristics described by battery models and (2) utilizing these algebraic models in an optimization framework involving genetic algorithms for determining the optimal charging profiles over the cycle life of the battery. The utility of the present framework in determining the optimal charging solutions is illustrated with various real‐life usage scenarios such as fast charging and extension of cycle life. The proposed solution can be utilized onboard for generating the optimal charging profiles over cycle life of the battery.     

Tailoring the photoluminescent properties of samarium and dysprosium codoped calcium zirconate perovskites for WLED applications

This study investigates the photoluminescent properties of Dy³⁺/Sm³⁺ single and codoped CaZrO₃perovskites that were prepared through conventional solid state ceramic route method. X-ray diffraction studies confirmed the orthorhombic (Pnma) perovskite structure of the calcined samples. Photoluminescence studies of Dy³⁺doped CaZrO₃ systems showed emission peaks at 484 nm and 575 nm due to the transition between ⁴F_9/2–⁶H_15/2 and ⁴F_9/2–⁶H_13/2 levels respectively. Intense red emissions were observed for Sm³⁺ doped CaZrO₃ systems at around 567 nm, 603 and 646 nm that corresponds to the ⁴G_5/2 → ⁶H_5/2, ⁴G_5/2 → ⁶H_7/2 and ⁴G_5/2 → ⁶H_9/2 transitions of Sm³⁺. Two different emissions were observed at different excitations for Dy³⁺/Sm³⁺ codoped CaZrO₃systems. Pleasant white light emission was achieved for the CaZr_0.9Sm_0.025Dy_0.075O₃ system at 354 nm excitation with CIE color coordinates (0.3310, 0.3349) with a quantum yield of 16.14%, makes this system a promising candidate for WLED and display device applications. Uniform grain morphology and elemental composition of CaZr_0.9Sm_0.025Dy_0.075O₃ sample was revealed from scanning electron microscopic and electron dispersive X-ray analysis. The presence of elements and their oxidation states in the calcined samples for doubly doped system was confirmed from X-Ray photoelectron spectroscopicstudies.     

Improving the performance of sulfonated polymer membrane by using sulfonic acid functionalized hetero-metallic metal-organic framework for DMFC applications

Proton transport played a crucial part in the fuel cells, sensors, and batteries. The electrolyte used in fuel cells should possess high proton conductivity and good chemical stability. Herein, taking advantage of the high proton conductivity of metal-organic framework (MOF) and the good chemical stability of branched polymers, a new heterometallic mediated MOF (Zr-Cr-SO₃H) is synthesized and utilized as a filler in the highly branched sulfonated polymer (BSP). In addition, Zr-SO₃H MOF is also prepared for comparison. Transmission electron microscope study shows that the prepared MOF particles are spherical in size and interconnected through nanosheets. The optimized quantity of MOFs inside the polymer matrix improves the water sorption, mechanical property, and proton conductivity. The composite membranes display an improved open-circuit voltage than the pristine BSP membrane. By comparing the Zr-SO₃H MOF incorporated composite membrane, Zr-Cr-SO₃H MOF incorporated composite membranes display higher proton conductivity and peak power density in a single-cell test. In particular, the single-cell fabricated with Zr-Cr-SO₃H MOF incorporated composite membrane is able to reach the peak power density of 64.6 mWcm⁻² at 60°C, which is 26% greater than the Nafion 212 membrane. Furthermore, this work offers a new strategy for the utilization of hetero-metal MOF as a filler for proton exchange membrane applications.     

Dual Defect-Passivation Using Phthalocyanine for Enhanced Efficiency and Stability of Perovskite Solar Cells

Semiconducting molecules have been employed to passivate traps extant in the perovskite film for enhancement of perovskite solar cells (PSCs) efficiency and stability. A molecular design strategy to passivate the defects both on the surface and interior of the CH₃NH₃PbI₃ perovskite layer, using two phthalocyanine (Pc) molecules (NP-SC₆-ZnPc and NP-SC₆-TiOPc) is demonstrated. The presence of lone electron pairs on S, N, and O atoms of the Pc molecular structures provides the opportunity for Lewis acid–base interactions with under-coordinated Pb²⁺ sites, leading to efficient defect passivation of the perovskite layer. The tendency of both NP-SC₆-ZnPc and NP-SC₆-TiOPc to relax on the PbI₂ terminated surface of the perovskite layer is also studied using density functional theory (DFT) calculations. The morphology of the perovskite layer is improved due to employing the Pc passivation strategy, resulting in high-quality thin films with a dense and compact structure and lower surface roughness. Using NP-SC₆-ZnPc and NP-SC₆-TiOPc as passivating agents, it is observed considerably enhanced power conversion efficiencies (PCEs), from 17.67% for the PSCs based on the pristine perovskite film to 19.39% for NP-SC₆-TiOPc passivated devices. Moreover, PSCs fabricated based on the Pc passivation method present a remarkable stability under conditions of high moisture and temperature levels.     

Biomass feedstock supply chain design – a taxonomic review and a decomposition-based methodology

In this paper, we present a taxonomic review of the literature devoted to the use of operations research approaches for the design and operation of biomass feedstock supply chains (BFSCs). A total of 185 publications that have appeared from 1989 to 2017 are classified based on (1) the embedded optimisation subproblems; (2) the modelling methodologies used for their formulations; and (3) the methods employed for their solution. Our objective of using this classification scheme is to highlight the presence of some useful substructures in a BFSC problem that can, then, be exploited in developing its solution procedure. We illustrate this idea on some generic BFSC problems and present a Dantzig–Wolfe decomposition-based methodology for developing customised approaches to effectively tackle these difficult and large-sized BFSC problems. Finally, we suggest several promising future research directions.     

Single Amino Acid Replacement in G-7039 Leads to a 70-fold Increase in Binding toward GHS-R1a

The growth hormone secretagogue receptor type 1a (GHS-R1a) is a class A rhodopsin-like G protein coupled receptor (GPCR) that is expressed in a variety of human tissues and is differentially expressed in benign and malignant prostate cancer. Previously, the peptidomimetic [1-Nal⁴,Lys⁵(4-fluorobenzoyl)]G-7039 was designed as a molecular imaging tool for positron emission tomography (PET). However, this candidate was a poor binder (IC₅₀=69 nm ), required a lengthy four-step radiosynthesis, and had a cLogP above 8. To address these challenges, we now report on changes targeted at the 4^th position of G-7039. A 2-fluoropropionic acid (2-FPA) group was added on to Lys⁵ to determine the potential binding affinity of the [¹⁸F]-2-FP radiolabeled analogue, which could be prepared by simplified radiochemistry. Lead candidate [Tyr⁴,Lys⁵(2-fluoropropionyl)]G-7039 exhibited an IC₅₀ of 0.28 nm and low picomolar activity toward GHS-R1a. Molecular docking revealed a molecular basis for this picomolar affinity.     

Stability analysis and robust synchronization of fractional‐order competitive neural networks with different time scales and impulsive perturbations

This article mainly examine a class of robust synchronization, global stability criterion, and boundedness analysis for delayed fractional‐order competitive type‐neural networks with impulsive effects and different time scales. Firstly, by endowing the robust analysis skills and a new class of Lyapunov‐Krasovskii functional approach, the error dynamical system is furnished to be a robust adaptive synchronization in the voice of linear matrix inequality (LMI) technique. Secondly, by ignoring the uncertain parameter terms, the existence of equilibrium points are established by means of topological degree properties, and the solution representation of the considered network model are provided. Thirdly, a novel global asymptotic stability condition is proposed in the voice of LMIs, which is less conservative. Finally, our analytical results are justified with two numerical examples with simulations.