Study on catalytic properties of graphene/molybdenum sulfide under near-infrared light irradiation

Graphene/MoS2 hybrid material was prepared by the hydrothermal method. The hybrid material was characterized by X-ray diffraction spectrum, Raman spectra, transmission electron microscope and UV-vis-NIRS. It was used as a near-infrared photocatalyst to catalyze and degrade Rhodamine B (RhB). The results showed that when the concentration of the RhB solution was 50.0 mg·L–1, the pH value of the solution was 7, the volume of the solution was 50.0 mL, the amount of G/MoS2 catalyst was 0.05 g and near-infrared radiation was carried out for 3 h, the degradation rate of RhB in the 50 mL solution reached 96.5%. When MoS2 was used as the photocatalyst, the degradation rate of RhB was only 75.5%. After 5 times of recycling, the catalytic efficiency of the hybrid photocatalyst was still more than 90%, indicating that the catalyst is very stable.

Experimental and theoretical investigation of heat transfer characteristics of cylindrical heat pipe using Al2O3–SiO2/W-EG hybrid nanofluids by RSM modeling approach

Nanofluids are emerging two-phase thermal fluids that play a vital part in heat exchangers owing to its heat transfer features. Ceramic nanoparticles aluminium oxide (Al2O3) and silicon dioxide (SiO2) were produced by the sol-gel technique. Characterizations have been done through powder X-ray diffraction spectrum and scanning electron microscopy analysis. Subsequently, few volume concentrations (0.0125–0.1%) of hybrid Al2O3–SiO2 nanofluids were formulated via dispersing both ceramic nanoparticles considered at 50:50 ratio into base fluid combination of 60% distilled water (W) with 40% ethylene glycol (EG) using an ultrasonic-assisted two-step method. Thermal resistance besides heat transfer coefficient have been examined with cylindrical mesh heat pipe reveals that the rise of power input decreases the thermal resistance and inversely increases heat transfer coefficient about 5.54% and 43.16% respectively. Response surface methodology (RSM) has been employed for the investigation of heat pipe experimental data. The significant factors on the various convective heat transfer mechanisms have been identified using the analysis of variance (ANOVA) tool. Finally, the empirical models were developed to forecast the heat transfer mechanisms by regression analysis and validated with experimental data which exposed the models have the best agreement with experimental results.

Rapid Screening of Butyl Paraben Additive in Toner Sample by Molecularly Imprinted Photonic Crystal

In consideration of the endocrine disrupting effects caused by the butyl paraben (BP), a portable visual sensor has been developed based on the photonic crystal and molecular imprinting technology for the rapid screen of BP in toner sample, which is a type of aqueous cosmetic to soften the face skin. By integrating the self-reporting and molecular recognition properties, the molecular imprinting photonic crystal (MIPC) sensor can display obvious color changes regularly according to the concentration of BP. Based on the “color guide”, the content of BP in toner sample can be estimated directly with the naked eye. In addition, the Bragg diffraction spectrum of MIPC can red shift linearly with the increase of the concentration of BP in sample solution with correlation coefficient as 0.9968. The quantitative determination of BP can be achieved through the optical fiber spectrometer with detection limit as 0.022 mmol·L−1. With good selectivity, this MIPC film can recognize BPs against the complex sample matrix, showing a standard addition recovery of 107% for the real samples.

Impact of Al2O3 and Dy2O3 Substitution on the Physical, Structural, and Radiation Shielding Properties of Li2O-B2O3 Glass System

A new series of lithium-borate glass systems (23Li2O-72B2O3 in mol%) were synthesized with the substitution of Al2O3 (5 mol.%) as a modifier and doped with 0.3 and 0.5 mol% of Dy2O3. Four series of glasses (S1, S2, S3 and S4) were synthesized via the conventional melt-quenching technique and characterized by using UV-Visible-NIR absorption spectrometer and Fourier transform infrared (FTIR) spectroscopy. The current investigation gives further insight on the structural and optical properties of the samples. The diffraction spectrum obtained from the X-ray Diffraction (XRD) analysis shows no typical peaks in the glass system, which indicates its amorphous phase. The optical properties of Al3+ and Dy3+ ions were evaluated and found that there is a pivot effect for the addition of Al2O3 and Dy2O3 for the glass system. Notably, the sample S2 shows different behaviours for physical, structural, and optical properties compared with other prepared glass samples that can be attributed to the increment of Al2O3. Besides, the physical and ionizing shielding features were investigated for current glass samples. The radiation shielding properties were examined within the energy range of 0.015 until 15 MeV. The sample S4 has the optimum radiation shielding features as a result of the addition of Dy2O3. Hence, the composition attributes a new glass system that can be used in various applications such as radiation dosimeter and photon shielding materials.

Anti-Diabetic Activity of Silver Nanoparticles Synthesized From The Hydroethanolic Extract of Myristica Fragrans Seeds

Myristica fragrans, also known as nutmeg is a spice that cures various diseases. This study aimed to synthesize silver nanoparticles from a hydroethanolic extract of Myristica fragrans seeds (MFHE) and evaluate their anti-diabetic properties. To MFHE, AgNO3 solution was added and exposed to sunlight to produce silver nanoparticles from hydroethanolic seed extract of Myristica fragrans (MFHENP). The MFHENP was characterized by numerous techniques. UV-visible spectroscopy confirmed the formation of silver nanoparticles by the absorption peak at 430nm. Scanning electron microscopy (SEM) studies revealed the shape and size of the particles at the range of 50-60nm. Energy-dispersive X-ray spectroscopy (EDX) disclosed the presence of silver ions. X-ray diffraction spectrum confirmed the crystalline nature of silver nanoparticles by the peak at 39o. FTIR analysis revealed the functional groups present in MFHE as well as in MFHENP and Zeta potential analysis was found to be 14mV. Furthermore, in-vitro anti-diabetic activity was investigated. MFHENP showed significant efficiency against the inhibition of alpha-amylase and alpha-glucosidase enzymes and also MFHENP retarded the glucose transport across the membrane which is analyzed by glucose diffusion and glucose uptake assays. Acarbose is used as a standard for all these methods and MFHENP efficiency proves their therapeutic potential for the treatment of diabetes mellitus.

Synthesis and Characterization of Lanthanum Oxide La2O3 Net-like Nanoparticles By New Combustion Method

Herein is a new procedure to synthesize lanthanum oxide (La2O3) nanoparticles, which is eco-friendly and simple. The La2O3 nanoparticles were prepared by sol-gel method using modification in time of stirring, type of PEG, and temperature of the reaction. Scherer's formula was used to estimate the average crystallite of La2O3 nanoparticle size from X-ray diffraction peaks of powder. The measured average particle size of La2O3 nanoparticles using the major signals of the X-ray diffraction spectrum after calcination was 37 nm. Fourier Transform Infrared Spectroscopy technique was done to analyze the chemical structure of synthesized materials. The surface morphology of obtained nanoparticles was also studied by SEM and AFM techniques. Thermal gravimetric analysis was investigated by Thermogravimetric analysis (TGA) to confirm the thermal stability of synthesized nanoparticles.

A novel approach to the preparation of manganese - doped zinc silicate luminescent material according to the precipitation method

The purpose of this work is to study the effect of some precipitation conditions on the luminescent properties of manganese-doped zinc silicate when synthesized in a new approach - impregnated precipitation method. The samples are characterized by thermal analysis, infrared IR, luminescent spectrum (PL), X-ray diffraction spectrum and scanning electron microscope (SEM). The results showed that manganese - doped zinc silicate luminescent material prepared by the impregnated precipitation method has higher luminescence than the traditional co-precipitation method. Samples with the highest luminescent properties were synthesized under the following conditions: concentration of Zn (CH3COO)2 is 1M, the precipitate aging time of 20 minutes, the washed filtered precipitate, impregnated with Mn2+ with a content of 1.5 % mol compared to the total metal, dried at 80 °C and then heat at 900 0C for 45 minutes. The obtained product is single-phase zinc silicate with composition of Zn1,97Mn0,03SiO4, rhombic structure with most particles varying in size of 0.3 - 0.5 µm, emitting green light with λmax = 525 nm when excited by UV rays with wavelength of 254 nm. Forming a single-phase Zn2SiO4 crystal at 900 0C for 45 minutes allowed to reduce the energy required for the sintering process compared with the solid - phase reaction method.

Synthesis, characterization and functional evaluation of gold nanoparticles prepared using Dovyalis abyssinica leaf extracts as reducing and surface capping agent

Green synthesis of nanoparticles using plants and microorganisms is biologically safe, cost effective, and environmentally friendly technology. Gold nanoparticles (Au NPs) were synthesized using aqueous extracts of leaves of Dovyalis abyssinica as reducing and surface capping agent and the catalytic activity, antibacterial action and antioxidant potential of the synthesized AU NPs were evaluated. Firstly, HAuCl4 was synthesized in the laboratory from metallic gold and hydrochloric acid using a predesigned method. Secondly, Au NPs was synthesized by mixing HAuCl4 and the plant extract at 45 oC with a digestion time of 1 h. The size of the nanoparticles was modulated by varying the ratio of the plant extract and HAuCl4 with known concentrations. The synthesized Au NPs showed strong absorption around 540 nm which lies in the characteristic absorption region of Au metal nanoparticles (520–580 nm). The X-ray diffraction spectrum of the synthesized Au NPs showed characteristic crystalline structures of gold. The scanning electron spectroscopy images of the synthesized Au NPS revealed the presence of mixed shapes predominantly of irregular shapes and a particle size analyzer displayed an average size of 63.13 nm. The fourier-transform infrared spectrum of Au NPS confirmed the presence of amine, carbonyl and hydroxyl functional groups as surface capping molecules. Although the synthesized Au NPs showed poor bacterial growth inhibition activity on two selected bacteria, it demonstrated excellent free radical scavenging activity against 2, 2-Diphenyl-2-picrylhydrazyl (DPPH) radical and good catalytic activity for degrading bromothymol blue and methyl red compounds. In contrast to the hexane and ethyl acetate extracts, the aqueous fraction was identified as powerful reducing fraction for the synthesis of Au NPs in this experiment.

Research of Fluorescent Properties of a New Type of Phosphor with Mn2+-Doped Ca2SiO4

Fluorescent optical fiber temperature sensors have attracted extensive attention due to their strong anti-electromagnetic interference ability, good high-voltage insulation performance, and fast response speed. The fluorescent material of the sensor probe directly determines the temperature measurement effect. In this paper, a new type of fluorescent material with a Mn2+-doped Ca2SiO4 phosphor (CSO:Mn2+) is synthesized via the solid-state reaction method at 1450 °C. The X-ray diffraction spectrum shows that the sintered sample has a pure phase structure, although the diffraction peaks show a slight shift when dopants are added. The temperature dependence of the fluorescence intensity and lifetime in the range from 290 to 450 K is explored with the help of a fluorescence spectrometer. Green emission bands peaking at 475 and 550 nm from Mn2+ are observed in the fluorescence spectra, and the intensity of emitted light decreases as the temperature rises. The average lifetime of CSO:Mn2+ is 17 ms, which is much higher than the commonly used fluorescent materials on the market. The fluorescence lifetime decreases with increasing temperature and shows a good linear relationship within a certain temperature range. The research results are of great significance to the development of a new generation of fluorescence sensors.