Depth sensing indentation analysis of electrochemically synthesized polythiophene

A depth sensing indentation (DSI) test with associated analyses was used to investigate some mechanical properties (reduced elastic modulus, hardness and creep) of electrochemically synthesized polythiophene (PT). Internal friction (IF) and energy absorption representing the degree of anelastic deformation of the material were also determined using cyclic and step-load/unload (SLU) test procedure, respectively. The indentation load–displacement (P–h) curves of the sample were obtained under different peak loads with two load holding time, 70 and 300 s. Elastic modulus values were determined by analyzing of these curves with Oliver–Pharr (O–P) and Feng–Ngan (F–N) procedures. The obtained results pointed out that both methods yielded comparable results for 300 s, while the corresponding values of 70 s were not well-matched with each other. These results were explained by the saturation of creep effects within 300 s holding period. Creep analysis exhibited that creep displacement increases at a declining rate with time and finally reaches a constant rate. Cyclic test results indicated that IF values approach saturation after several cycles and the saturation value of IF was found to be depending on loading rate. From SLU tests, an upper limit of the normalized dissipated energy was observed.     

On Adaptive Output Feedback Controf Robotic Manipulators with Online Disturbance Estimation

The problem of disturbance estimation and compensation for adaptive output feedback type controllers are investigated. Specifically two adaptive output feedback controllers designed for robotic manipulators are extended to compensate external disturbances which are common in robotic applications with repetitive task. The uncertain disturbance term in the robot dynamics is modeled as a fixed term plus a combination of sinusoidal signals. The overall stability and convergence of the tracking error for both controllers is ensured via Lyapunov based analysis. Extensive simulation studies are presented to illustrate the feasibility of the proposed method.     

Enantioselective Synthesis of α‐Hydroxy Ketones via Benzaldehyde Lyase‐Catalyzed C−C Bond Formation Reaction

(R)‐Benzoins and (R)‐2‐hydroxypropiophenone derivatives are formed on a preparative scale by benzaldehyde lyase (BAL)‐catalyzed C−C bond formation from aromatic aldehydes and acetaldehyde in aqueous buffer/DMSO solution with remarkable ease in high chemical yield and high optical purity. The substrate range of this thiamin diphosphate‐dependent enzyme was examined with respect to a broad applicability of this benzoin condensation‐type reaction in stereoselective synthesis.     

Regioselective Alkylations of Cyclic 1,3-Diketones via Metalated Dimethylhydrazones

Cyclic 1,3- diketones 1 are transformed into their 2,2-dimethylhydrazones 2 , which can be alkylated regio-selectively at different positions after mono-, di-, tri-, and tetrametalation. Monometalated C-2 unsubstituted hydrazones afford C-2 and N-alkylation, monometalated C-2 substituted hydrazones afford only C-2 alkylation. The regioselectivity of the alkylation of the polymetalated hydrazones follows Hauser's rule according to the sequence: NH- > C-4 Ha > C-5 > C-4 Hb. Hydrolysis of the product hydrazones 3–5 afforded mono- and polyalkylated 1,3- diketones 7 in good yields.     

An iterated greedy algorithm for the planning of yarn-dyeing boilers

Yarn dyeing is a critical link in the textile production chain that consumes the most time and energy. Today's dyeing shops receive hundreds of demands with thousands of different colors, different due dates, and different production requirements. This situation has made it very difficult for the human brain to create a minimum-cost production plan by complying with the due dates. In this study, a real-life problem of a company operating in the textile industry is discussed and a solution has been developed for the planning of yarn-dyeing boilers. The application was held in Bursalı Textile, which is the major towel manufacturer operating in Turkey. The problem dealt with is basically in the nature of the variable-size bin-packing problem (VSBPP). The limited availability of bins (boilers) of different sizes and the packing of the items (yarn work orders) with due date constraints are the original aspects of this study. Multi-objective mixed integer programming model is developed to minimize two objectives. For the solution, the preemptive method called the lexicographic approach, in which the objectives are solved in order, is preferred. As the first objective, the overcapacity usage is minimized and then the second objective, which is the boiler usage cost, is minimized. Given that the VSBPP is strongly NP-hard, an iterated greedy algorithm with two different decoding approaches is proposed. Computational experiments were conducted on 20 randomly generated benchmark instances and a real-world industrial dataset. The numerical results show that good solutions can be obtained in seconds using the proposed approaches.     

Room-Temperature Exceptional-Point-Driven Polariton Lasing from Perovskite Metasurface

Excitons in lead bromide perovskites exhibit high binding energy and high oscillator strength, allowing for a strong light-matter coupling regime in the perovskite-based cavities localizing photons at the nanoscale. This opens up the way for the realization of exciton-polariton Bose–Einstein condensation and polariton lasing at room temperature – the inversion-free low-threshold stimulated emission. However, polariton lasing in perovskite planar photon cavities without Bragg mirrors has not yet been observed and proved experimentally. In this study, perovskite metasurface is employed, fabricated with nanoimprint lithography, supporting so-called exceptional points to demonstrate the room-temperature polariton lasing. The exceptional points in exciton-polariton dispersion of the metasurface appear upon optically pumping in the nonlinear regime in the spectral vicinity of a symmetry-protected bound state in the continuum providing high mode confinement with the enhanced local density of states beneficial for polariton condensation. The observed lasing emission possesses high directivity with a divergence angle of 1° over one axis. The employed nanoimprinting approach for solution-processable large-scale polariton lasers is compatible with various planar photonic platforms suitable for on-chip integration.     

Automated steel surface defect detection and classification using a new deep learning-based approach

Neural Computing and Applications - In this study, a new deep learning-based approach has been developed that detects and classifies surface defects that occur in the steel production process. The...     

Gradient Type-II CdSe/CdSeTe/CdTe Core/Crown/Crown Heteronanoplatelets with Asymmetric Shape and Disproportional Excitonic Properties

Characterized by their strong 1D confinement and long-lifetime red-shifted emission spectra, colloidal nanoplatelets (NPLs) with type-II electronic structure provide an exciting ground to design complex heterostructures with remarkable properties. This work demonstrates the synthesis and optical characterization of CdSe/CdSeTe/CdTe core/crown/crown NPLs having a step-wise gradient electronic structure and disproportional wavefunction distribution, in which the excitonic properties of the electron and hole can be finely tuned through adjusting the geometry of the intermediate crown. The first crown with staggered configuration gives rise to a series of direct and indirect transition channels that activation/deactivation of each channel is possible through wavefunction engineering. Moreover, these NPLs allow for switching between active channels with temperature, where lattice contraction directly affects the electron–hole (e–h) overlap. Dominated by the indirect transition channels over direct transitions, the lifetime of the NPLs starts to increase at 9 K, indicative of low dark-bright exciton splitting energy. The charge transfer states from the two type-II interfaces promote a large number of indirect transitions, which effectively increase the absorption of low-energy photons critical for nonlinear properties. As a result, these NPLs demonstrate exceptionally high two-photon absorption cross-sections with the highest value of 12.9 × 10⁶ GM and superlinear behavior.     

Development of polycaprolactone-based electrospun pH-sensitive sensors as instant colorimetric indicators for food packaging

In the present study, polycaprolactone/polyethylene glycol (PCL/PEG) electrospun nanofibres with different anthocyanin (1%, 2%, 3%, and 5%) were fabricated for the instant measurement of pH, especially for applications—such as food freshness detection—where quick response is required. The solution, surface, chemical, thermal, wettability, mechanical, and release properties of the samples were evaluated by viscosity measurements, scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), contact angle measurements, and tensile tests, respectively. The colorimetric analyses were also investigated against the solutions at different pH values and bacterial solutions. Finally, the on-site performance of the sensor was evaluated. Anthocyanin addition initially lowered the solution viscosity, resulting in thinner fibres with a diameter of 288 nm. The diameters were increased up to 395 nm with the increasing anthocyanin. Anthocyanin addition enhanced the wettability and the mechanical properties, and the contact angles decreased to 43°. The highest modulus was observed for 1% anthocyanin, with a value of 6.162. The release experiments revealed that the anthocyanin-loaded samples released a large amount of anthocyanin (between ~12% and 38%) in the first 15 s. The colorimetric analyses showed that PCL/PEG nanofibre mats with 2% and 3% anthocyanin concentrations were the most capable pH-sensitive sensors for detecting pH changes from 2 to 8. As a result, it can be concluded that 3% anthocyanin is the threshold value for the production of the anthocyanin-loaded nanofibre mats, and these structures are promising for the instant detection of pH proved by the on-site application.