Antibacterial cotton fabrics with in situ generated silver and copper bimetallic nanoparticles using red sanders powder extract as reducing agent

Using aqueous extraction of red sanders powder as a reducing agent, silver and copper bimetallic nanoparticles were in situ generated in cotton fabrics. Silver and copper nanoparticles were also generated separately for comparison. The resulted nanocomposite cotton fabrics (NCFs) were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and antibacterial tests. SEM analysis indicated the generation of more number of nanoparticles when bimetallic source solutions were used. Further, the size range of the generated bimetallic nanoparticles was found to be lower than when individual metal nanoparticles were generated in NCFs. XRD analysis confirmed the in situ generation of silver and copper nanoparticles when equimolar bimetallic salt source solutions were utilized. The NCFs with bimetallic nanoparticles exhibited higher antibacterial activity against both Gram-negative and Gram-positive bacteria and hence can be considered for applications as antibacterial bed and dressing materials.     

Aromatic compounds produced by endophytic fungi isolated from red alga Asparagopsis taxiformis - Falkenbergia stage

Endophytic fungi were isolated from red alga Asparagopsis taxiformis - Falkenbergia stage, collected from the Brazilian coast, and were identified as Annulohypoxylon stygium (AT-03) and A. yungensis (AT-06) based on their macro/micromorphological and molecular features. Bioassay-guided fractionation of the EtOAc extract from laboratory cultures of both strains yielded known compounds pyrogallol from A. stygium, (3R)-scytalone and (3R,4R)-4-hydroxy-scytalone from A. yungensis. Pyrogallol was active against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli strains. An inactive fraction from A. stygium afforded two additional compounds, (3R,4R)-3,4,5-trihydroxy-1-tetralone and tyrosol. Optically active compounds had their stereochemistry determined by circular dichroism (CD) spectroscopy.     

Crystal structure and pale‐yellow emitting properties of K3Gd1–xDyxB6O12 solid solutions

A new potassium dysprosium polyborate, K₃DyB₆O₁₂, has been prepared via the high‐temperature molten salt method and structurally characterized by single‐crystal X‐ray diffraction analysis. The structure can be described as a three‐dimensional framework composed of isolated bicyclic [B₅O₁₀]^5? groups and Dy³⁺ and K⁺ ions. The Fourier transform IR (FT–IR) and ultraviolet–visible (UV–Vis) spectra were investigated. A series of K₃Gd_1–xDy_xB₆O₁₂ phosphors was prepared and their photoluminescence properties were studied. The K₃Gd_1–xDy_xB₆O₁₂ phosphors exhibit a strong yellow emission band at 577 nm (the ⁴F_9/2→⁶H_13/2 transition of Dy³⁺) under UV excitation of 275 nm (the ⁸S_7/2→⁶I_J transition of Gd³⁺), suggesting the occurrence of the energy transfer Gd³⁺→Dy³⁺. The optimized doping concentration of the Dy³⁺ ion was 8 mol%. We may expect that K₃Gd_1–xDy_xB₆O₁₂ is a promising pale‐yellow emission phosphor for visual displays or solid‐state lighting.     

Scalable Biosynthesis of the Seaweed Neurochemical,Kainic Acid

Kainic acid, the flagship member of the kainoid family of natural neurochemicals, is a widely used neuropharmacological agent that helped unravel the key role of ionotropic glutamate receptors, including the kainate receptor, in the central nervous system. Worldwide shortages of this seaweed natural product in the year 2000 prompted numerous chemical syntheses, including scalable preparations with as few as six‐steps. Herein we report the discovery and characterization of the concise two‐enzyme biosynthetic pathway to kainic acid from l ‐glutamic acid and dimethylallyl pyrophosphate in red macroalgae and show that the biosynthetic genes are co‐clustered in genomes of Digenea simplex and Palmaria palmata. Moreover, we applied a key biosynthetic α‐ketoglutarate‐dependent dioxygenase enzyme in a biotransformation methodology to efficiently construct kainic acid on the gram scale. This study establishes both the feasibility of mining seaweed genomes for their biotechnological prowess.     

Comparative study between two fabricated potentiometric sensors to enhance selectivity towards ferrous ions

Electroanalytical methods are highly selective for measuring electrical quantities including the charge, potential and current with their relation to chemical parameters. They are widely applied in various fields such as biochemical analysis, industrial quality control and environmental monitoring. They have many advantages over other techniques in that they are not time consuming and are specific for certain oxidation states of certain elements which give these techniques high selectivity and sensitivity features. This paper is based on two parts: the first part describes the fabrication of screen‐printed electrodes (SPEs) modified with methyl red as electroactive material, while second part describes the preparation and characterization of Fe(II)–methyl red complex using various spectroscopic tools, the complex being used for the construction of carbon paste electrodes (CPEs). The two proposed electrodes were successfully applied for the determination of Fe(II) in water and pharmaceutical (pharovit) samples. The electrodes under investigation show potentiometric response for Fe(II) in the concentration range 8.0 × 10^?7–1.0 × 10^?2 and 5.0 × 10^?7–1.0 × 10^?2 M at 25°C for SPE and CPE, respectively, and the electrode response is independent of pH in the range 1.5–7.0. These sensors show Nernstian slopes of 29.1 ± 0.2 and 29.7 ± 0.16 mV decade^?1 with detection limit values of 8.0 × 10^?7 and 5.0 × 10^?7 M for SPE and CPE, respectively. These electrodes show fast response time of 6 and 4 s and exhibit a lifetime of 100 and 30 days for SPE and CPE, respectively. The mechanism of chemical reaction between modifier and Fe(II) on the SPE surface was studied using infrared spectra, scanning electron microscopy and energy‐dispersive X‐ray analysis. The proposed potentiometric method was validated according to the IUPAC recommendations. The results obtained using the proposed sensors were comparable with those obtained with inductively coupled plasma analysis.     

Fabrication of red-emitting CaAlSiN3: Eu2+ through phosphor-in-glass approach for application in rear combination lamp

In this study, the red-emitting phosphor-in-glass (PiG) using the CaAlSiN₃: Eu²⁺ (CASN) phosphor is reported for the first time. The CASN: Eu²⁺ PiG samples with a maximum luminous flux of 25.1–29.4 for l minute at laser power of 1 W/mm² was obtained using a low-temperature glass frit and GPS furnace. Despite the increase in the phosphor from 15 to 25 wt%, the PiG produced at low temperature of 380 °C showed robust properties. Finally, the red PiG module designed for rear lamp applications maintains over 90% lumens for a minute at 350 mA and achieves an intense red light having a color temperature of 4589 K.     

Molecular Design Strategy for Orange Red Thermally Activated Delayed Fluorescence Emitters in Organic Light-Emitting Diodes (OLEDs)

Pure organic molecules based thermally activated delayed fluorescence (TADF) emitters have been successfully developed in recent years for their propitious application in highly efficient organic light emitting diodes (OLEDs). In the case of orange red emitters, the non-radiative process is known to be a serious issue due to its lower lying singlet energy level. However, recent studies indicate that there are tremendous efforts put to develop efficient orange red TADF emitters. In addition, the external quantum efficiency (EQE) of heteroaromatic based orange red TADF OLEDs surpassed 30 %. Such heteroaromatic type emitters showed wide emission spectra; therefore, more attention is being paid to develop highly efficient orange red TADF emitters along with good color purity. Herein, the recent progress of orange red TADF emitters based on molecular structures, such as cyanobenzene, heteroaromatic, naphthalimide, and boron-based acceptors, are reviewed. Further, our insight on these acceptors has been provided by their photophysical studies and device performances. Future perspectives of orange red TADF emitters for real practical applications are discussed.     

不同晶体结构Gd2(MoO4)3:Eu3+荧光粉的合成及其发光性能研究

采用溶胶凝胶-燃烧法,柠檬酸为络合剂合成出系列Gd₂(MoO₄)₃:Eu³⁺荧光粉.利用X射线衍射(XRD)、扫描电子显微镜(SEM)和荧光光谱对样品的结构、形貌和发光性能进行了研究.XRD分析表明:稀土离子与柠檬酸为1:0.5时,800℃热处理获得单斜结构的Gd₂(MoO₄)₃:Eu³⁺荧光粉.单斜结构的Gd₂(MoO₄)₃:Eu³⁺荧光粉到正交结构的Gd₂(MoO₄)₃:Eu³⁺荧光粉的转换可以通过改变稀土离子与柠檬酸摩尔比和热处理温度等合成条件实现.Gd₂(MoO₄)₃:Eu³⁺荧光粉的形貌受合成条件的影响.荧光光谱研究表明:Gd₂(MoO₄)₃:Eu³⁺荧光粉的主发射峰位于616 nm处来自于Eu³⁺的⁵D₀→⁷F₂电偶极跃迁.正交结构的Gd₂(MoO₄)₃:Eu³⁺荧光粉发射强度明显高于单斜结构的荧光粉.计算⁵D₀→⁷F₂与⁵D₀→⁷F₁跃迁发射的相对强度比值表明:正交结构的Gd₂(MoO₄)₃:Eu³⁺中Eu³⁺局域环境的对称性较高。     

CaLuBO4∶Tb^3+荧光粉的制备及发光性质

采用高温固相反应法合成了不同Tb^3+掺杂浓度的CaLuBO4∶xTb^3+荧光粉,研究了样品的晶体结构和发光性质。在紫外光激发下,样品的发射光谱由Tb3+离子的5D3→7FJ(J=6,5,4)和5D4→7FJ′(J′=6,5,4,3)特征发射组成,其中位于545 nm和554 nm附近的5D4→7F5跃迁发射强度最大。荧光粉的激发光谱是由位于紫外区的Tb3+的4f-5d和f-f跃迁构成的。研究了Tb3+浓度对样品发光性质的影响。测量并分析了CaLuBO4∶xTb^3+荧光粉的5D3能级和5D4能级荧光寿命。结果表明,CaLuBO4∶xTb^3+是一种适于紫外激发的新型黄绿光荧光粉。     

Fabrication and luminous properties of phosphor ceramic for application in automotive laser headlight

We report on the optimization of fabrication of a ceramic phosphor plate (CPP) using α-Al₂O₃ as functional materials for an automotive laser headlamp. The prepared CPP shows the high luminous characteristics with increasing α-Al₂O₃ contents because of the light scattering of the hexagonal structure of α-Al₂O₃ materials. We investigated the correlation between α-Al₂O₃ and thickness of CPP. The luminous properties of the CPP are improved and optimized according to the variables of one. We found that the prepared sample is a potential material for future solid-state laser lighting in application as an automotive headlamp.