Modeling thin film formation by Ultrasonic Spray method: A case of PEDOT:PSS thin films

Recent improvements in electronic and optoelectronic devices based on solution processable polymers have motivated development of scalable processing techniques like Ultrasonic Spray technique. Including potential for roll to roll fabrication, it has many other strengths. However, with spray coating it can be difficult to prepare films with a smooth surface. Here, we present model for Ultrasonic Spray deposition of thin films, which establish a clear correlation between process parameters and the film formation process, which ultimately decide the structural features of the thin films. Based on the time to cover the spray deposition area by the sprayed droplets and the time for droplet evaporation, a balance parameter has been defined. It provides a mean to determine suitable process parameters for uniform film formation by Ultrasonic Spray method. The model is further modified for the region of higher solution flow rates, where non-uniformity in droplet distribution is introduced. The predictions based on the model have been experimentally verified with thin films of poly(3,4-ethylene dioxythiophene) doped with polystyrene sulphonic acid (PEDOT:PSS). The method presented here can be used to predict proper deposition parameters for smooth film deposition by Ultrasonic Spray technique. Finally, the effect of film morphology on the sheet resistance of thin films of PEDOT:PSS is also presented.     

Experimental determination of photofission cross-sections of Th using electron accelerator

Photofission cross-section of ²³²Th was measured using Bremsstrahlung radiation energy 7.4–9.2 MeV with energy step of 0.3 MeV by employing Lexan polycarbonate film as Solid State Nuclear Track Detectors (SSNTD). The photon intensity from the Microtron accelerator facility was estimated to be 10¹⁰ photons/s at a distance of 15 cm from the Bremsstrahlung converter using EGS-4 code (Nelson et al., 1985). Photofission cross-sections were evaluated using fission fragment angular distribution measurements. The present experimental results were compared with EMPIRE-2.19 (Herman et al., 2005) code prediction of RIPL-1 and RIPL-2 ( and ) and a new analytical formula (Gupta and Saxena, 2005) for fission barrier.     

Evaluation of Bubbling Vacuum Cooling for the Small-Size Cooked Pork

Vacuum cooling has notable advantages including fast cooling rate, cleanness, and high energy efficiency. However, the weight loss of food after being vacuum cooled was unsatisfactory, especially for meat products. Immersion vacuum cooling can significantly reduce the weight loss of food compared with traditional vacuum cooling procedures, but the cooling rate is unacceptable. To overcome this problem, here, a novel vacuum cooler, bubbling vacuum cooler, was designed and evaluated for the small-size cubic cooked pork with a side length of 1.5 cm from about 60 to 4 °C. Experimental results indicated that bubbling vacuum cooling can reduce the weight loss (about ??2.3%) of food compared to both vacuum cooling (about 12.4%) and immersion vacuum cooling (about 0.5%) (P?<?0.05). Further, bubbling vacuum cooling can cool the sample with a slightly more rapid cooling rate (0.10 °C/s) contrasted with immersion vacuum cooling (0.07 °C/s) (P?>?0.05). For the chromatism value of sample, no significant difference was found between immersion vacuum cooling and bubbling vacuum cooling (P?>?0.05). The textural property of sample cooled by bubbling vacuum cooling was close to (for hardness, elasticity, chewiness, and shear force, P?>?0.05) and better (for cohesiveness, P?<?0.05) than that of immersion vacuum cooling. Thus, our experiment demonstrated that cooked pork cooled by bubbling vacuum cooling has a lower weight loss rate and a more rapid cooling rate than that of immersion cooling.     

Characterization of protein immobilization on nanoporous gold using atomic force microscopy and scanning electron microscopy

Nanoporous gold (NPG), made by dealloying low carat gold alloys, is a relatively new nanomaterial finding application in catalysis, sensing, and as a support for biomolecules. NPG has attracted considerable interest due to its open bicontinuous structure, high surface-to-volume ratio, tunable porosity, chemical stability and biocompatibility. NPG also has the attractive feature of being able to be modified by self-assembled monolayers. Here we use scanning electron microscopy (SEM) and atomic force microscopy (AFM) to characterize a highly efficient approach for protein immobilization on NPG using N-hydroxysuccinimide (NHS) ester functionalized self-assembled monolayers on NPG with pore sizes in the range of tens of nanometres. Comparison of coupling under static versus flow conditions suggests that BSA (Bovine Serum Albumin) and IgG (Immunoglobulin G) can only be immobilized onto the interior surfaces of free standing NPG monoliths with good coverage under flow conditions. AFM is used to examine protein coverage on both the exterior and interior of protein modified NPG. Access to the interior surface of NPG for AFM imaging is achieved using a special procedure for cleaving NPG. AFM is also used to examine BSA immobilized on rough gold surfaces as a comparative study. In principle, the general approach described should be applicable to many enzymes, proteins and protein complexes since both pore sizes and functional groups present on the NPG surfaces are controllable.     

INTERACTION OF SURFACE RADIATION WITH CONJUGATE MIXED CONVECTION FROM A VERTICAL PLATE WITH MULTIPLE NONIDENTICAL DISCRETE HEAT SOURCES

Some of the important results of a numerical investigation into interaction of surface radiation with conjugate mixed convection from a discretely heated vertical plate with three nonidentical heat sources are provided here. The heat sources with identical rate of volumetric heat generation are placed flush-mounted along the plate in the descending order of their height from the bottom to the top ends of the plate. The heat sources are positioned at the leading edge, center, and the trailing edge of the plate, while the cooling medium considered is air, which is assumed to be radiatively transparent. The governing equations for fluid flow and heat transfer are initially converted into vorticity-stream function form and are later solved using the finite volume method coupled with Gauss-Seidel iterative solver. A computer code is written for the purpose. The effects of modified Richardson number, surface emissivity, and thermal conductivity on temperature distribution, peak temperature, drag coefficient, and relative contributions of mixed convection and radiation to heat dissipation are studied.     

Object Touch by a Humanoid Robot Avatar Induces Haptic Sensation in the Real Hand

Humanoid robot embodiment is a recently developed form of mediated embodiment. In 2 studies, we report and quantify a new haptic (touch) illusion during embodiment of a humanoid robot. Around 60% of the users in our studies reported haptic sensations in their real hand when they observed their robot avatar touching a curtain with its hand. Critically, our study shows for the first time that users can experience haptic sensations from a nonanthropomorphic embodied limb/agent with visual feedback alone (i.e. no haptic feedback provided). The results have important implications for the understanding of the cognitive processes governing mediated embodiment and the design of avatar scenarios.     

Impact properties of thermoplastic composites

The excellent properties exhibited by thermoplastic composites at much reduced weight have attracted attention in the development of products in different sectors. Thermoplastic (TP) composites, because of their distinctive properties as well as ease of manufacturing, have emerged as a competitor against the conventional thermoset resin-based composites. Depending on the application, these composites may undergo impact events at various velocities and often fail in many complex modes. Hence, the development of TP composites having high energy-dissipation at (the desired) much-reduced weight has become a challenging task, but it is a problem which may be alleviated through the appropriate selection of materials and fabrication processes. Furthermore, fibre surface modification has been shown to increase fibre-matrix interfacial adhesion, which can lead to improved impact resistance. Textile preforms are helpful in acting as a structural backbone in the composites since they offer a relatively free hand to the composite designer to tailor its properties to suit a specific application. Additionally, hybrid textile composite structures may help in achieving the desired properties at much lower weight.

Simulation software can play a significant role in the evaluation of composites without damaging physical samples. Once the simulation result has been validated with actual experimental results, it should be possible to predict the test outcomes for different composites, with different characteristics, at different energy levels without conducting further physical tests. Various numerical models have been developed which have to be incorporated into these software tools for better prediction of the result.

In the current issue of Textile Progress, the effects of various materials and test parameters on impact behaviour are critically analyzed. The effect of incorporating high-performance fibres and natural fibres or their hybrid combination on the impact properties of TP composites are also discussed and the essential properties of TP polymers are briefly explained. The effects of fibre and matrix hybridization, environmental factors, various textile preform structures and fibre surface modification treatments on the impact properties of thermoplastic composites are examined in detail. Various numerical models used for impact analysis are discussed and the potential applications of TP composites in automobile, aerospace and medical sectors are highlighted.     

Edge Effect Elimination in Single-Mixture Blind Source Separation

Blind source separation (BSS) of single-channel mixed recording is a challenging task that has applications in the fields of speech, audio and bio-signal processing. Ensemble empirical mode decomposition (EEMD)-based methods are commonly used for blind separation of single input multiple outputs. However, all of these EEMD-based methods appear in the edge effect problem when cubic spline interpolation is used to fit the upper and lower envelopes of the given signals. It is therefore imperative to have good methods to explore a more suitable design choice, which can avoid the problems mentioned above as much as possible. In this paper we present a novel single-mixture blind source separation method based on edge effect elimination of EEMD, principal component analysis (PCA) and independent component analysis (ICA). EEMD represents any time-domain signal as the sum of a finite set of oscillatory components called intrinsic mode functions (IMFs). In extreme point symmetry extension (EPSE), optimum values of endpoints are obtained by minimizing the deviation evaluation function of signal and signal envelope. Edge effect is turned away from signal by abandoning both ends’ extension parts of IMFs. PCA is applied to reduce dimensions of IMFs. ICA finds the independent components by maximizing the statistical independence of the dimensionality reduction of IMFs. The separated performance of edge EPSE-EEMD-PCA-ICA algorithm is compared with EEMD-ICA and EEMD-PCA-ICA algorithms through simulations, and experimental results show that the former algorithm outperforms the two latter algorithms with higher correlation coefficient and lower relative root mean square error (RRMSE).     

A Study on Process Parameters of Ultrasonic Assisted Micro EDM Based on Taguchi Method

Experimental investigation of ultrasonic assisted micro electro discharge machining was performed by introducing ultrasonic vibration to workpiece. The Taguchi experimental design has been applied to investigate the optimal combinations of process parameters to maximize the material removal rate and minimize the tool wear. Analysis of variance (ANOVA) was performed and signal-to-noise (S/N) ratio was determined to know the level of importance of the machining parameters. Based on ANOVA, ultrasonic vibration at 60% of the peak power with capacitance of 3300 PF was found to be significant for best MRR. The machining time plays a significant role in the tool wear. The results were confirmed experimentally at 95% confidence interval.     

Grafting of polyaniline onto the radiation crosslinked chitosan

In this paper we report the chemical grafting of polyaniline onto the radiation crosslinked chitosan. Chitosan is crosslinked using 8 MeV electron beam and Co⁶⁰ γ-ray in the presence of CCl₄ as sensitizer. The so-obtained crosslinked chitosan is grafted with polyaniline (PANI) chemically using ammonium peroxy disulphate (APS) as an initiator. Grafted polymer is characterized by dissolution, swelling, UV–vis–NIR spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis, DC conductivity and nanoindentation studies. From the dissolution studies, grafting of PANI onto the crosslinked chitosan is confirmed. From the weight of films before and after grafting, grafting percentage is calculated. Grafting percentage increases as the monomer concentration increases and decreases with increase in crosslinking. This may be due to the decrease in the penetration of monomer onto the chitosan matrix with increase in crosslinking density. This is verified from SEM (cross-sectional view) of blend. UV–vis–NIR spectrum shows absorption peaks of PANI. Electrical property of grafted polymer is improved after doping with 1 M HCl. The change in volume conductivity is from 10⁻¹¹ to 10⁻⁵ S/cm and surface conductivity from 10⁻¹⁰ to 10⁻² S/cm. From TGA it is observed that grafted polymer and doped polymer are thermally stable.