Dazzling cool white light emission from Ce3+/Sm3+ activated LBZ glasses for W-LED applications

We synthesized a batch of co-doped (Ce³⁺+Sm³⁺): LBZ glass specimens by melt quenching process and their structural and radiation properties were studied by employing XRD, FE-SEM, optical absorption, photoluminescence and lifetime measurements. UV–Vis–NIR absorption studies of the co-doped (Ce³⁺+Sm³⁺): LBZ glassy matrix displays pertinent bands of both Ce³⁺ and Sm³⁺ ions. Individually doped Sm³⁺: LBZ glass exhibit bright orange emission at 603?nm (⁴G_5/2 → ⁶H_7/2) under the excitation of 403?nm. Nevertheless, the luminescence intensities pertaining to Sm³⁺ were extraordinarily increased by co-doping with Ce³⁺ ions to Sm³⁺: LBZ glassy matrices because of energy transfer from Ce³⁺ to Sm³⁺. The fluorescence spectra of co-doped (Ce³⁺+Sm³⁺): LBZ exhibits characteristic emission bands of Ce³⁺ (441?nm, blue) and Sm³⁺ (603?nm, reddish orange) under the excitation of 362?nm. Decay curves of Ce³⁺ and Sm³⁺ ions in co-doped glass has been fitted to double exponential nature. The decreasing lifetime of donor ion and rising lifetime of acceptor ion in double doped glass could support the energy transfer from Ce³⁺ to Sm³⁺ ions in the host matrix. The CIE coordinates and CCT values were calculated for all the obtained co-doped glassy samples from their luminescence spectra. By adding Ce³⁺ ions to individually doped Sm³⁺: LBZ glass matrix, the emitting color changes from reddish orange to white light which resembles the energy transfer from Ce³⁺ to Sm³⁺ ions. These studies, perhaps implied that attained co-doped (Ce³⁺+Sm³⁺): LBZ glassy samples are potential materials for white lighting appliances.     

The influence of process parameters and heat treatment on the properties of cold sprayed silver coatings

Cold spray coating technology is a promising low temperature variant of thermal spray technology which can deposit pure, dense and thick coatings at a rapid rate. Unlike the other thermal spray coating techniques, cold spray is especially suitable for depositing coatings with high electrical and thermal conductivity as the integrity of the feedstock is maintained during the coating process. In the present study, the effect of process parameters and heat treatment on the properties of silver coatings has been investigated. An attempt has been made to correlate the powder particle velocity with the properties and microstructure of the coating. The effect of heat treatment temperature and atmosphere on the properties of the coatings, especially electrical conductivity, has been studied in detail in conjunction with a thorough analysis of the evolution of microstructure of the coatings.     

Pure H2 Production by Decomposition of Methane Over Ni Supported on Hydroxyapatite Catalysts

The catalytic decomposition of CH₄ for the production of pure H₂ is carried out over Ni supported on hydroxyapatite [Ca₅(PO₄)₃(OH)] catalysts at 650 °C and atmospheric pressure. CH₄ decomposition activity is decreased with time on stream and finally deactivated completely. The physicochemical properties of the fresh catalysts are characterized by XRD, DTA/TG, TPR and SEM techniques along with CHNS analyses of the used samples. It is found that the 30 wt% Ni/HAp displayed higher H₂ production rates over the other Ni loadings, which is correlated with Ni metal surface area measured by O₂ pulse chemisorption. IICT communication number: 051211.     

Synthesis,characterization and bactericidal activity of silica/silver core–shell nanoparticles

Silica/silver core–shell nanoparticles (NPs) were synthesized by coating silver NPs on silica core particles (size ~300 ± 10 nm) via electro less reduction method. The core–shell NPs were characterized for their structural, morphological, compositional and optical behavior using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and UV–Visible spectroscopy, respectively. The size (16–35 nm) and loaded amount of silver NPs on the silica core were found to be dependent upon reaction time and activation method of silica. The bactericidal activity of the NPs was tested by broth micro dilution method against both Bacillus subtilis (gram positive) and Escherichia coli ATCC25922 (gram negative) bacterium. The bactericidal activity of silica/silver core–shell NPS is more against E. coli ATCC25922, when compared to B. subtilis. The minimal inhibitory concentration of the core–shell NPs ranged from 7.8 to 250 μg/mL and is found to be dependent upon the amount of silver on silica, the core. These results suggest that silica/silver core–shell NPs can be utilized as a strong substitutional candidate to control pathogenic bacterium, which are otherwise resistant to antibiotics, making them applicable in diverse medical devices.     

Effect of Powder Metallurgy Process and its Parameters on the Mechanical and Electrical Properties of Copper-Based Materials: Literature Review

Powder Metallurgy and Metal Ceramics - As the world is shifting towards renewable sources of energy, the demand for copper is increasing due to its excellent electrical and corrosion resistance...     

Electrospinning of poly (3-hydroxybutyric acid) and gelatin blended thin films: fabrication, characterization, and application in skin regeneration

A tissue engineering scaffold should mimic the structure and biological function of native extracellular matrix proteins. Electrospinning is a simple and versatile method to produce ultrathin fibers for tissue engineering. Blended submicron fibers of poly (3-hydroxybutyric acid) and gelatin were electrospun using 1,1,1,3,3,3 hexafluoro-2-propanol as solvent. Cross linking of fibers was achieved using glutaraldehyde, and the resultant fibers were tested and analyzed using scanning electron microscopy (SEM), differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, and Fourier transformed infrared spectroscopy (FTIR).The fibers were found to exhibit good tensile strength. Degradation studies were performed and analyzed using SEM and FTIR and proved the stability of fibers for tissue engineering applications. The fibrous scaffold supported the growth and rapid proliferation of human dermal fibroblasts and keratinocytes with normal morphology, thus proving its reliability in using it as a potential scaffold for skin regeneration.     

Effect of Notch Root Radius on the Apparent Fracture Toughness in CNT and Carbon Fiber Reinforced, Epoxy-Matrix Hybrid Composite

Significantly improved fracture resistance (in terms of fracture toughness) can be imparted to monolithic materials by adopting composite design methodology based on fiber and nano particulate reinforcement technology. The present work describes the fracture behaviour of one such reinforced material; in this case, carbon fiber (C_f)- and carbon nanotube (CNT)- reinforced epoxy composite. The C_f and CNT reinforced, epoxy-matrix hybrid composite in longitudinal and transverse orientations with varied finite notch root radii (in the range of 120–750 μm) are subjected to mode-I (tensile) fracture. The fracture toughness/resistance (K_Q) of the material is then evaluated and analyzed by investigating the influence of varying notch root radii in longitudinal and transverse orientations. Such an analysis has revealed that the present unidirectional epoxy hybrid composite exhibits a critical notch root radius of 270 μm in longitudinal and 390 μm in transverse orientation.     

Video content authentication techniques: a comprehensive survey

In this digital day and age, we are becoming increasingly dependent on multimedia content, especially digital images and videos, to provide a reliable proof of occurrence of events. However, the availability of several sophisticated yet easy-to-use content editing software has led to great concern regarding the trustworthiness of such content. Consequently, over the past few years, visual media forensics has emerged as an indispensable research field, which basically deals with development of tools and techniques that help determine whether or not the digital content under consideration is authentic, i.e., an actual, unaltered representation of reality. Over the last two decades, this research field has demonstrated tremendous growth and innovation. This paper presents a comprehensive and scrutinizing bibliography addressing the published literature in the field of passive-blind video content authentication, with primary focus on forgery/tamper detection, video re-capture and phylogeny detection, and video anti-forensics and counter anti-forensics. Moreover, the paper intimately analyzes the research gaps found in the literature, provides worthy insight into the areas, where the contemporary research is lacking, and suggests certain courses of action that could assist developers and future researchers explore new avenues in the domain of video forensics. Our objective is to provide an overview suitable for both the researchers and practitioners already working in the field of digital video forensics, and for those researchers and general enthusiasts who are new to this field and are not yet completely equipped to assimilate the detailed and complicated technical aspects of video forensics.     

Robustness of the partitions in grouping multi-item inventories

A recent work obtained closed-form solutions to the.problem of optimally grouping a multi-item inventory into subgroups with a common order cycle per group, when the distribution by value of the inventory could be described by a Pareto function. This paper studies the sensitivity of the optimal subgroup boundaries so obtained. Closed-form expressions have been developed to find intervals for the subgroup boundaries for any given level of suboptimality. Graphs have been provided to aid the user in selecting a cost-effective level of aggregation and choosing appropriate subgroup boundaries for a whole range of inventory distributions. The results of sensitivity analyses demonstrate the availability of flexibility in the partition boundaries and the cost-effectiveness of any stock control system through three groups, and thus also provide a theoretical support to the intuitive ABC system of classifying the items.