Structural and emission properties of Eu3+‐doped alkaline earth zinc‐phosphate glasses for white LED applications

Quaternary alkaline earth zinc‐phosphate glasses in molar composition (40 ? x)ZnO – 35P₂O₅ – 20RO – 5TiO₂ – xEu₂O₃ (where x=1 and R=Mg, Ca, Sr, and Ba) were prepared by melt quenching technique. These glasses were studied with respect to their thermal, structural, and photoluminescent properties. The maximum value of the glass transition temperature (T_g) was observed for BaO network modifier mixed glass and minimum was observed for MgO network modifier glass. All the glasses were found to be amorphous in nature. The FT‐IR suggested the glasses to be in pyrophosphate structure, which matches with the theoretical estimation of O/P atomic ratio and the maximum depolymerization was observed for glass mixed with BaO network modifier. The intense emission peak was observed at 613 nm (⁵D₀→⁷F₂) under excitation of 392 nm, which matches well with excitation of commercial n‐UV LED chips. The highest emission intensity and quantum efficiency was observed for the glass mixed with BaO network modifier. Based on these results, another set of glass samples was prepared with molar composition (40 ? x)ZnO – 35P₂O₅ – 20BaO – 5TiO₂ – xEu₂O₃ (x=3, 5, 7, and 9) to investigate the optimized emission intensity in these glasses. The glasses exhibited crystalline features along with amorphous nature and a drastic variation in asymmetric ratio at higher concentration (7 and 9 mol%) of Eu₂O₃. The color of emission also shifted from red to reddish orange with increase in the concentration of Eu₂O₃. These glasses are potential candidates to use as a red photoluminsecent component in the field of solid‐state lighting devices.     

Synthesis of Dihydrobenzofuro[3,2-b]chromenes as Potential 3CLpro Inhibitors of SARS-CoV-2: A Molecular Docking and Molecular Dynamics Study

The recent emergence of pandemic of coronavirus (COVID-19) caused by SARS-CoV-2 has raised significant global health concerns. More importantly, there is no specific therapeutics currently available to combat against this deadly infection. The enzyme 3-chymotrypsin-like cysteine protease (3CLpro) is known to be essential for viral life cycle as it controls the coronavirus replication. 3CLpro could be a potential drug target as established before in the case of severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV). In the current study, we wanted to explore the potential of fused flavonoids as 3CLpro inhibitors. Fused flavonoids (5a,10a-dihydro-11H-benzofuro[3,2-b]chromene) are unexplored for their potential bioactivities due to their low natural occurrences. Their synthetic congeners are also rare due to unavailability of general synthetic methodology. Here we designed a simple strategy to synthesize 5a,10a-dihydro-11H-benzofuro[3,2-b]chromene skeleton and it's four novel derivatives. Our structural bioinformatics study clearly shows excellent potential of the synthesized compounds in comparison to experimentally validated inhibitor N3. Moreover, in-silico ADMET study displays excellent druggability and extremely low level of toxicity of the synthesized molecules. Further, for better understanding, the molecular dynamic approach was implemented to study the change in dynamicity after the compounds bind to the protein. A detailed investigation through clustering analysis and distance calculation gave us sound comprehensive data about their molecular interaction. In summary, we anticipate that the currently synthesized molecules could not only be a potential set of inhibitors against 3CLpro but also the insights acquired from the current study would be instrumental in further developing novel natural flavonoid based anti-COVID therapeutic spectrums.     

Controlling the Er content of porous silicon using the doping current intensity

The results of an investigation on the Er doping of porous silicon are presented. Electrochemical impedance spectroscopy, optical reflectivity, and spatially resolved energy dispersive spectroscopy (EDS) coupled to scanning electron microscopy measurements were used to investigate on the transient during the first stages of constant current Er doping. Depending on the applied current intensity, the voltage transient displays two very different behaviors, signature of two different chemical processes. The measurements show that, for equal transferred charge and identical porous silicon (PSi) layers, the applied current intensity also influences the final Er content. An interpretative model is proposed in order to describe the two distinct chemical processes. The results can be useful for a better control over the doping process.

PACS

81.05.Rm; 82.45.Rr     

Structural and color tunable properties in Sm3+/Eu3+-doped Ca3Bi(PO4)3 phosphor for solar cell and w-LED applications

Journal of Materials Science: Materials in Electronics - Crystalline eulytite-type Ca3Bi(PO4)3 (CBP) phosphors activated with Sm3+ and combination of Sm3+ & Eu3+ ions have been prepared by...     

Metallurgical Approach Towards Explaining Optimized EDM Process Parameters for Better Surface Integrity of AISI D2 Tool Steel

Many attempts have been made to model and optimize performance parameters of Electrical Discharge Machining (EDM) process. In this investigation, the experimental design includes L9 orthogonal array based on the Taguchi methodology. The corresponding effect of input current, duty cycle and spark on time, on surface integrity, has been studied on AISI D2 tool steel. The residual stress measurement is done using X-ray diffraction method. The obtained output results regarding material removal rate, surface roughness, crack density, and residual stress have been modeled and optimized by regression equation and Genetic algorithm respectively. In this investigation, a metallurgical approach has been introduced towards the explanation of the resulted optimized response parameters.     

A system dynamics model for the supply chain procurement transport problem: comparing spreadsheets,fuzzy programming and simulation approaches

This article proposes a simulation approach based on system dynamics for operational procurement and transport planning in a two-level, multi-product and multi-period supply chain. This work uses the Vensim^® simulation tool to highlight the potential of system dynamics for supply chain simulation. A real continuous simulation application is presented in an automobile supply chain. The effectiveness of the proposed model is validated through the comparison of the results provided by spreadsheet-based simulation, fuzzy multi-objective programming and system dynamics-based simulation models. The fundamental point of this paper is that the simulation model is the most effective approach in quantifying the trade-off between number of truck shipments and average inventory level. In this case, the number of truck shipments is to be minimised, resulting in a higher inventory level. If the average inventory level were minimised, then there would be more truck shipments. Here, it is shown the benefit of this type of simulation model in reducing inventory by about 10%.     

Inhibitory property of Piper betel extract against photosensitization-induced damages to lipids and proteins

The protective activity of Piper betel ethanolic extract (PE) against the photosensitization-induced damage to lipids and proteins of rat liver mitochondria has been studied. PE could effectively prevent lipid peroxidation, as assessed by measuring thiobarbituric acid reactive substances, lipid hydroperoxide and conjugated diene. In addition, it prevented photo-induced oxidation of proteins in a concentration-dependent manner. Furthermore, its preventive capacity against iron-mediated lipid peroxidation was also confirmed. The protective activity of PE could be attributed to its free radical and singlet oxygen scavenging properties. The activity of PE was primarily due to its phenolic constituents, which were identified as chavibetol and 4-allylpyrocatechol.     

Effects of irrigation water quantities and seasonal variation on oil content and fatty acid composition of sunflower (Helianthus annuus L.)

A field experiment was conducted in the North Western Group of the Gezira Scheme (longitude 32°48′ and latitude 15°14′) for four successive seasons, two winter and two summer seasons, during the years 1999–2002, to study the effect of different irrigation water quantities (300, 400, 500, 600 and 700 mm per season) on oil content and oleic acid and linoleic acid percentages in two sunflower cultivars [Rodeo, an open‐pollinated variety, and Hysun33, a hybrid). The experiment was designed in a split plot design, with four replicates. The cultivars were allotted to the sub‐plots while the irrigation treatments were assigned to main plots. The results showed that different irrigation water quantities had significant effects on all parameters studied and the cultivar Hysun33 gave a higher oil content (36.6%) at 700 mm whereas the open‐pollinated variety Rodeo gave 34.1% oil at that level of irrigation. The overall percentages of oleic and linoleic acids were 29.7 and 58.1 in winter and 47.6 and 43.1 in summer, respectively. Copyright © 2007 Society of Chemical Industry     

Development of a multiplex PCR for rapid detection of verocytotoxin-producing Escherichia coli O26 in raw milk and ground beef

Verocytotoxin-producing Escherichia coli (VTEC) O26 is an emergent pathotype that has caused an increasing number of sporadic cases and outbreaks of gastroenteritis, hemorrhagic colitis, and hemolytic uremic syndrome in the United States and Europe. Many cases are associated with the consumption of milk and undercooked or fermented meats. The stx(2) strains of VTEC O26 seem to be more likely to cause human infections than isolates expressing only stx(1). The isolation and identification of VTEC O26 from foods is labor intensive and time-consuming. We developed a multiplex PCR (M-PCR) assay for the identification and characterization of E. coli O26 VTEC and its detection in raw milk and ground beef. The method is based on the amplification of the wzx, stx(1), and stx(2) genes for the simultaneous detection of the O26 antigen and verocytotoxin types 1 and 2. This M-PCR assay had a sensitivity of 10(8) CFU/ml when applied to a bacterial suspension and of 10(6) CFU/ml or g when applied to both inoculated milk and minced beef samples. This M-PCR assay also was highly specific, and results were consistently negative for negative controls (nonpathogenic E. coli strains, uninoculated milk and beef samples, and samples inoculated with the nontarget microorganisms). This method could be used for the rapid detection of E. coli O26 VTEC from foods and for the rapid identification and characterization of clinical and environmental isolates.     

Tensile Deformation Modeling of a Homogenized Cast Alloy 625: Effects of Large Grain Size

Metallurgical and Materials Transactions A - In the present study, tensile deformation behavior of a coarse-grained (> 1 mm) cast alloy 625 has been investigated by applying empirical and...