Statistical adaptive sensing by detectors with spectrally overlapping bands

It has recently been reported that by using a spectral-tuning algorithm, the photocurrents of multiple detectors with spectrally overlapping responsivities can be optimally combined to synthesize, within certain limits, the response of a detector with an arbitrary responsivity. However, it is known that the presence of noise in the photocurrent can degrade the performance of this algorithm significantly, depending on the choice of the responsivity spectrum to be synthesized. We generalize this algorithm to accommodate noise. The results are applied to quantum-dot mid-infrared detectors with bias-dependent spectral responses. Simulation and experiment are used to show the ability of the algorithm to reduce the adverse effect of noise on its spectral-tuning capability.     

Facile synthesis of reduced graphene oxide from Azadirachta indica for optical power limiting applications: an eco-friendly approach

Reduced graphene oxide (rGO) was synthesized successfully from dead leaves of neem trees using a novel synthesis method comprising combustion, washing, and drying. The synthesized carbonaceous material was subjected to systematic characterization analysis. The rGO material was subjected to X-ray powder diffraction analysis to determine the grain size and other structural parameters. The existence of defect and graphitic band was confirmed by FT-Raman analysis. The presence of a 2D band around 2700 cm^?1 indicated the formation of multi-layered graphene. SEM analysis was used to examine the structural morphology of the synthesized material. FTIR spectra revealed the information about the spectral properties of rGO. Compositional analysis revealed the presence of carbon and other contents in the specimen. The title material may be used in optical power limiters, according to z-scan and optical limiting analysis. The results indicate that the cost of synthesis would be significantly reduced when done on a large scale, using this procedure. Furthermore, rGO produced by this method is environmentally friendly, nontoxic and has a high yield.

     

Sorption of Cu(II) ions by nano‐scale zero valent iron supported on rubber seed shell

This study focused on synthesising nano‐scale zero valent iron (NZVI) impregnated on a low‐cost agro‐waste material, rubber seed shell (RSS), by borohydride reduction method. The characterisation studies of NZVI‐RSS were performed by Fourier transform infrared spectroscopy, scanning electron microscopy and X‐ray diffraction. The adsorption execution of NZVI‐RSS for Cu(II) ions evacuation from synthetic wastewater was explored by batch studies. The optimum condition for the present adsorption system is as follows: Cu(II) ion concentration = 25 mg/l; solution pH = 6.0; contact time = 30 min; NZVI‐RSS dose = 3 g/l; temperature = 30°C. The sorption data were best portrayed by pseudo‐first‐order and Freundlich models. The outcomes demonstrated the multilayer sorption of Cu(II) ions by NZVI‐RSS. The Langmuir capacity was observed as 48.18 mg/g. Thermodynamic parameters, ΔG °, ΔH ° and ΔS ° were ascertained, and it was watched that the adsorption system was unconstrained and exothermic. The sticking probability for Cu(II) ions by NZVI‐RSS was found to be high at lower temperature. At long last, the research inquire about reasoned that NZVI‐RSS has demonstrated unrivalled adsorption capacity. Also NZVI‐RSS is thought to be really green and financially amicable support for wastewater treatment.Inspec keywords: adsorption, copper, X‐ray diffraction, scanning electron microscopy, wastewater treatment, Fourier transform infrared spectroscopyOther keywords: nano‐scale zero valent iron, rubber seed shell, copper ions, borohydride reduction method, NZVI‐RSS, Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, adsorption execution, synthetic wastewater, Langmuir capacity, Freundlich models, adsorption system, wastewater treatment, adsorption capacity, Cu     

Engineering On‐Surface Spin Crossover: Spin‐State Switching in a Self‐Assembled Film of Vacuum‐Sublimable Functional Molecule

The realization of spin‐crossover (SCO)‐based applications requires study of the spin‐state switching characteristics of SCO complex molecules within nanostructured environments, especially on surfaces. Except for a very few cases, the SCO of a surface‐bound thin molecular film is either quenched or heavily altered due to: (i) molecule–surface interactions and (ii) differing intermolecular interactions in films relative to the bulk. By fabricating SCO complexes on a weakly interacting surface, the interfacial quenching problem is tackled. However, engineering intermolecular interactions in thin SCO active films is rather difficult. Here, a molecular self‐assembly strategy is proposed to fabricate thin spin‐switchable surface‐bound films with programmable intermolecular interactions. Molecular engineering of the parent complex system [Fe(H₂B(pz)₂)₂(bpy)] (pz = pyrazole, bpy = 2,2′‐bipyridine) with a dodecyl (C₁₂) alkyl chain yields a classical amphiphile‐like functional and vacuum‐sublimable charge‐neutral Fe^II complex, [Fe(H₂B(pz)₂)₂(C₁₂‐bpy)] (C₁₂‐bpy = dodecyl[2,2′‐bipyridine]‐5‐carboxylate). Both the bulk powder and 10 nm thin films sublimed onto either quartz glass or SiO_x surfaces of the complex show comparable spin‐state switching characteristics mediated by similar lamellar bilayer like self‐assembly/molecular interactions. This unprecedented observation augurs well for the development of SCO‐based applications, especially in molecular spintronics.     

Automated synthesis of modular fixture designs using an evolutionary search algorithm

Fixture design is a complex problem that requires a designer to ensure that a workpiece is located deterministically, totally restrained and sufficiently supported during a manufacturing process. The use of modular fixtures, while presenting an opportunity to improve the responsiveness of a manufacturing system, adds to the complexity of the fixture design problem. The complexity is a result of the large number of fixture elements in a modular fixture system and the constraints of specified locations in which fixture elements can be placed in a grid-based modular system. This paper presents an evolutionary search algorithm that aids a fixture designer by exploring the large number of possible fixture designs and suggesting an appropriate one. The algorithm can explore the large solution space using a flexible and generic representation and it considers fixture layout and fixture configuration constraints concurrently in arriving at appropriate solutions. The initial results of the algorithm are promising.     

A codoping route to realize low resistive and stable p-type conduction in (Li, Ni):ZnO thin films grown by pulsed laser deposition

We report on the growth of Li-Ni codoped p-type ZnO thin films using pulsed laser deposition. Two mole percent Li monodoped ZnO film shows highly insulating behavior. However, a spectacular decrease in electrical resistivity, from 3.6 × 10(3) to 0.15 Ω cm, is observed by incorporating 2 mol % of Ni in the Li-doped ZnO film. Moreover, the activation energy drops to 6 meV from 78 meV with Ni incorporation in Li:ZnO lattice. The codoped [ZnO:(Li, Ni)] thin film shows p-type conduction with room temperature hole concentration of 3.2 × 10(17) cm(-3). Photo-Hall measurements show that the Li-Ni codoped p-ZnO film is highly stable even with UV illumination. XPS measurements reveal that most favorable chemical state of Ni is Ni(3+) in (Li, Ni): ZnO. We argue that these Ni(3+) ions act as reactive donors and increase the Li solubility limit. Codoping of Li, with other transitional metal ions (Mn, Co, etc.) in place of Ni could be the key to realize hole-dominated conductivity in ZnO to envisage ZnO-based homoepitaxial devices.     

Search for a novel zero thermal expansion material: dilatometry of the AgI-CuI system

AgI is a well-known superionic conductor possessing a negative thermal expansion (NTE) coefficient while CuI is a p-type semiconductor possessing a positive thermal expansion coefficient. Pellets of X-Ray Diffraction (XRD) characterized compositions in the AgI–CuI system namely, β AgI, γ AgI, Ag_0.5Cu_0.5I, Ag_0.25Cu_0.75I, Ag_0.10Cu_0.90I, Ag_0.05Cu_0.95I and γ CuI have been examined by quartz pushrod dilatometry measurements in order to look for a zero thermal expansion material. It is found that the systematic displacement of Ag by Cu gradually reduces the NTE anomaly in AgI. The composition Ag_0.25Cu_0.75I apparently exhibits near-zero thermal expansion. The results are discussed qualitatively in terms of relevant models.     

Effect of solvents on the structural, optical and morphological properties of Zn0.96Cu0.04O nanoparticles

Zn_0.96Cu_0.04O nanoparticles were synthesized by co-precipitation method using different solvents like ethanol, water and mixer of ethanol and water in 50:50 ratios. Crystalline phases and optical studies of the nanoparticles were studied by X-ray diffraction (XRD) and UV–visible photo-spectrometer. The XRD showed that the prepared nanoparticles have different microstructure without changing a hexagonal wurtzite structure. The calculated average crystalline size was high for ethanol (27.3 nm) due to the presence of more defects and low for water (26 nm) due to the reduction of defects and vacancies. The energy dispersive X-ray analyses confirmed the presence of Cu in ZnO system and the weight percentage is nearly equal to their nominal stoichiometry within the experimental error. The presence of lower Zn and Cu percentage in the sample prepared using ethanol than other solvents was due low reaction rate which was confirmed by XRD spectra. Water solvent has relatively stronger transmittance in the visible region which leads to the industrial applications especially in opto-electronic devices. The average crystalline size is slowly decreased from 27.3 nm (ethanol) to 26 nm (water) whereas energy gap is steadily increased from 3.56 eV (ethanol) to 3.655 eV (water) when water concentration is increased from 0 to 100 % in ethanol. Existence of functional groups and bonding were analyzed by FTIR spectra. The observed blue shift of UV emission from ethanol (349 nm) to water (340 nm) solution and the high I_UV/I_G ratio in water solution in photoluminescence spectra was due to the decrease of crystalline size and defects/secondary phases. The intensity of blue–green band emission was gradually decreased due to the reduction of defects and vacancies when water concentration is increased from 0 to 100 % in ethanol solution, which was consistent with the XRD observation.     

Ferulic acid‐loaded collagen hydrolysate and polycaprolactone nanofibres for tissue engineering applications

There is a great need for the progress of composite biomaterials, which are effective for tissue engineering applications. In this work, the development of composite electrospun nanofibres based on polycaprolactone (PCL) and collagen hydrolysate (CH) loaded with ferulic acid (FA) for the treatment of chronic wounds. Response Surface Methodology (RSM) has been applied to nanofibres factor manufacturing assisted by electrospinning. For wound healing applications, the authors have created the efficacy of CH, and PCL membranes can act as a stable, protective cover for wound, enabling continuous FA release. The findings of the RSM showed a reasonably good fit with a polynomial equation of the second order which was statistically acceptable at P  < 0.05. The optimised parameters include the quantity of hydrolysate collagen, the voltage applied and the distance from tip‐to‐collector. Based on the Box–Behnken design, the RSM was used to create a mathematical model and optimise nanofibres with minimum diameter production conditions. Using FTIR, TGA and SEM, optimised nanofibres were defined. In vitro, cytocompatibility trials showed that there was an important cytocompatibility of the optimised nanofibres, which was proved by cell proliferation and cell morphology. In this research, the mixed nanofibres of PCL and CH with ferulic could be a potential biomaterial for wound healing.Inspec keywords: tissue engineering, polymer fibres, wounds, electrospinning, nanofibres, response surface methodology, cellular biophysics, proteins, molecular biophysics, scanning electron microscopy, biomedical materials, nanomedicine, nanocomposites, nanofabrication, Fourier transform infrared spectraOther keywords: wound healing applications, PCL membranes, stable cover, protective cover, continuous FA release, RSM, optimised parameters, hydrolysate collagen, mathematical model, optimised nanofibres, polycaprolactone nanofibres, tissue engineering applications, composite biomaterials, composite electrospun nanofibres, collagen hydrolysate, ferulic acid, chronic wounds, Response Surface Methodology, nanofibres factor