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One-step growth of reduced graphene oxide on arbitrary substrates
摘要： Reduced graphene oxide (rGO) has inherited the outstanding electronic, optical, thermal and mechanical properties of graphene to a large extent, while maintaining sufficient chemically active sites. Therefore, it has attracted a great deal of research attention in the fields of energy storage, electronics, photonics, catalysis, environmental engineering, etc. Currently, the most popular way to prepare rGO is to reduce graphene oxide, which is obtained by modified Hummer methods using tedious treatments in a harsh environment, to rGO flakes. Industrial applications demand advanced preparation methods that can mass produce highly uniform rGO sheets on arbitrary substrates. In this work, a one-step growth process is introduced that utilizes cellulose acetate as a precursor, without any catalysts, to produce uniform ultrathin rGO films on various substrates and free-standing rGO powders. Systematic spectroscopic and microscopic studies on the resulting rGO are performed. Prototypes of electronic and optoelectronic devices, such as field effect transistors (FETs), photodetectors, and humidity sensors, are fabricated and tested, demonstrating the intriguing applications of our rGO materials across a wide range of fields.
关键词： electronic devices,reduced graphene oxide,one-step growth,cellulose acetate,optoelectronic devices
更新于2025-11-21 11:03:25
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Sensitive spectrophotometric determination of trace-level Co2+ in water based on acetate enhanced catalysis of Co2+
摘要： A sensitive spectrophotometric method was developed for the determination of trace-level Co2+ in water based on the acetate enhanced catalytic decolorization of methylene blue (MB) with Co2+ as a catalyst and peroxymonosulfate (PMS) as an oxidizing agent. This indirect spectrophotometric method was easy to operate due to the strong absorption of MB at a maximum absorption wavelength of 664 nm with a molar absorptivity of 5.88 × 104 L mol?1 cm?1. Under the selected reaction conditions of 10.0 mg L?1 MB, 60.0 mg L?1 PMS and 100.0 mg L?1 Ac?, the depletion extent of MB was linearly correlated with the concentration of Co2+ from 0.20 to 7.0 μg L?1 (R2 = 0.986) and then from 7.0 to 50.0 μg L?1 (R2 = 0.991), with a detection limit (3 s/k) of 0.10 μg L?1. It was found that this method possessed excellent anti-interference capability to various coexisting ions including similar transitional metals. The developed method was used to determine the Co2+ concentration in practical samples with satisfactory results.
关键词： Spectrophotometry,Methylene blue,Catalytic decolorization,Acetate,Trace-level Cobalt
更新于2025-11-19 16:56:35
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Eumelanin for Nature‐Inspired UV‐Absorption Enhancement of Plastics
摘要： In the human body, the black-brown biopigment eumelanin blocks the harmful ultraviolet (UV) radiation. In the plastics industry, additives are often added to polymers to increase their UV-absorption properties. We herein report an assessment of the biopigment eumelanin as a nature-inspired additive for plastics to enhance their UV-absorption. Since eumelanin is produced by natural sources and is non-toxic, it is an interesting candidate in the field of sustainable plastic additives. In this work, eumelanin-including films of commercial ethylene-vinyl acetate copolymer (EVA), a plastic used for packaging applications, were obtained by melt-compounding and compression molding. The biopigment dispersion in the films was improved by means of the Melanin Free Acid treatment (MFA). It was observed that eumelanin amounts as low as 0.8% wt. cause an increase of the UV absorption, up to one order of magnitude in the UVA range. We also evaluated the effect of eumelanin on the thermal and photostability of the films: the biopigment proved to be double-edged, working both as UV-absorption enhancer and photo-prooxidant, as thermogravimetric analysis (TGA) and infrared (IR) spectroscopy revealed.
关键词： Eumelanin,Packaging,Melanin Free Acid,UV-absorbers,Ethylene-vinyl acetate copolymer,UV-aging
更新于2025-10-22 19:40:53
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Third Order Nonlinear Properties of Pure and Na doped L-Arginine Acetate Single Crystal by Z-scan Technique
摘要： Single crystals of pure and Na doped L-arginine acetate (LAA) has been successfully grown from aqueous solution by slow evaporation technique. The crystalline qualities of the grown crystals were confirmed by powder X-ray diffraction studies. The nonlinear refractive index n2 and nonlinear susceptibility c(3) have been measured through the Z-scan technique. The results indicate that the compound exhibits reverse saturation absorption and self defocusing performance. Non-linear absorption co-efficient (b), the non-linear refractive index (n2), the real and imaginary parts of non-linear susceptibility c (3) have been measured at 632.8 nm.
关键词： Z-scan Technique,Na doped L-arginine acetate (LAA),Crystal
更新于2025-09-23 15:23:52
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Design, synthesis and photophysical studies of improved xanthene dye to detect acetate
摘要： Development of biomarkers of analytes with interest in clinic is an important field of study. In this work, we synthesized and analyzed the new fluorescent acetate-biomarker, Iso-PG. The mechanism of detection is the acetate buffer mediated proton transfer reaction. The rate constants involved were obtained, and we measured the change in the fluorescence lifetime produced as a consequence of the presence of acetate in the medium. Finally, we checked its potential use as acetate biomarker in synthetic serum.
关键词： FLIM,Acetate detection,Biomarkers,New dye
更新于2025-09-23 15:23:52
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Optical, thermal and gas separation properties of acetate-containing copoly(ether-imide)s based on 6FDA and fluorenyl diamines
摘要： The diamine, 9,9-bis[4-(4-amino-3-hydroxylphenoxy)phenyl]fluorene (BAHPPF) was synthesized by the modified two-step method. Then, a series of acetate-containing copoly(ether-imide)s were prepared by the copolymerization of BAHPPF, 9,9-bis(4-aminophenyl)fluorene (BAF) and 2,20-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) followed by chemical imidization. The structures and properties of the BAHPPF and copoly(ether-imide)s were characterized by nuclear magnetic resonance spectrometer (NMR), Fourier transform infrared spectrometer (FTIR), X-ray diffractometer (XRD), differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), ultraviolet-visible spectrophotometer (UV-VIS), and tensile testing. Single gas permeation performances of these copoly(ether-imide)s were also studied for five representative gases of interest including H2, O2, N2, CO2, and CH4. The experimental results showed that the copoly(ether-imide)s showed excellent optical properties with high light transmittance above 80.2% at 450 nm. The glass transition temperature of these copolymers were higher than 333°C. Their tensile strength and Young’s module also increased, and the elongation decreased with the decrease of BAHPPF. High gas permeabilities of copoly(ether-imide)s were obtained, and the ideal selectivity of CO2/CH4 was improved due to the introduction of acetate group and flexible ether linkage. These copoly(ether-imide)s could be applied to the field of optics and gas separation.
关键词： gas separation,acetate-containing,Copoly(ether-imide)s,thermal properties,light-colored and transparent
更新于2025-09-23 15:22:29
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DFT study of the influence of acetyl groups of cellulose acetate on its intrinsic birefringence and wavelength dependence
摘要： The effect of the acetyl groups of cellulose acetate (CA) on its intrinsic birefringence and its wavelength dependence was investigated using density functional theory (DFT). Seven types of CA repeating-unit models that differ in their degree of substitution (DS) and substitution sites were used in the calculations. The results suggested that the intrinsic birefringence (Δn°) and its wavelength dependence significantly depended on the conformations of the acetyl group at C6. Additionally, the intrinsic birefringence of CA films was estimated as the ensemble average of the calculated Δn° values of the conformers. The increase in the DS of CA led to a more negative intrinsic birefringence and a larger wavelength dependence. The computational results were in good qualitative agreement with the experimental results and suggested that conformational variety and/or its control would be important factors for the design of optical films containing CA.
关键词： Cellulose acetate,Density functional theory,Computational chemistry,Birefringence
更新于2025-09-23 15:21:21
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Development and Validation of Spectrophotometric and Spectrofluorimetric Methods for the Determination of Cyclobenzaprine HCl
摘要： Five simple and sensitive methods were developed for the determination of cyclobenzapirine hcl (CB) in presence of its degradation product anthraquinone (AQ). Method A dual wavelength spectrophotometry (DW); where two wavelengths were selected for the drug 283 and 306 nm in such a way that the difference in absorbance was zero for its degradation. Method B ratio difference spectrophotometry (RD) was depended on measuring the ratio difference between 290 and 305 nm. Method C was depended on measuring the peak amplitude of the first derivative of the ratio spectra (1DD) at 282 and 306 nm. Method D Isoabsorptive Point (ISO) at 280 nm Coupled with Second Derivative (2D). Method E depending on spectrofluorimetric determination of cyclobenzapirine HCl through quenching of uranyl acetate with ?exi 228 nm and ?em at 458 nm. Linearties were obtained in concentration range 5 μg/ml – 30 μg/ml in case of methods A, B, C and D, while in case of methods E linearity was obtained in concentration range of 1 μg/ml –10 μg/ml. The five methods were found to be specific for CB in presence of different concentration % of its degradation product. The five proposed methods were successfully applied for the determination of CB in Multirelax tablets. Statistical comparison between the results obtained by the proposed methods and that obtained by the official one for the determination of the drug was done, founding that there were no significant differences between them.
关键词： (1DD) Derivative ratio,Dual wavelength (DW),Isoabsorptive point (ISO),Spectrofluorimetry,Ratio difference (RD),Uranyl acetate,Cyclobenzapirine HCl (CB),Anthraquinone (AQ)
更新于2025-09-23 15:21:21
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Determination of Crystallinity and Thermal Stability of Newly Developed Thermoplastic Polyolefin Encapsulant for the c-Si PV Module Application
摘要： Thermoplastic polyolefin (TPO) is a newly developed non-crosslinking encapsulant for the crystalline silicon PV modules lamination. The degree of crystallinity and thermal stability of TPO have been studied and compared with the most commonly used ethylene vinyl acetate (EVA) copolymer encapsulant. The peak melting point and the degree of crystallinity have been determined with the help of differential scanning calorimeter (DSC) analysis. The crystallinity of both the encapsulant also studied with x-ray diffraction. DSC results show that there is no crosslinking reaction involved in the TPO encapsulant. Thermogravimetric analysis (TGA) is done to determine the thermal stability and thermal decomposition onset temperature. This work will help in understanding the thermal behavior and degree of crystallinity of newly developed TPO encapsulant, which can also potentially replace the EVA encapsulant for the PV module application.
关键词： encapsulant,polyolefin,crystallinity,thermal stability,ethylene vinyl acetate,photovoltaics
更新于2025-09-23 15:21:01
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Design of High-Symmetrical Magnesium-Organic Frameworks with Acetate as Modulator and Their Fluorescence Sensing Performance
摘要： During the formation of magnesium-organic frameworks, the coordination sphere of magnesium tends to be partially occupied by O-containing solvent molecules such as amides, which will dramatically decrease the symmetry of Mg-organic frameworks and thus lead to low stability. It is noted that up to now, most reported Mg-metal?organic frameworks (MOFs) (>80%) crystallize in the space groups whose symmetry is lower than that of a tetragonal system. In this work, we demonstrate that acetate (Ac) may act as modulator to eliminate the influence of amide solvent and improve the symmetry of Mg-organic frameworks. Two novel Mg-MOFs, namely, {[(CH3)NH3]4[Mg3(BTB)8/3(Ac)2(H2O)]}n (SNNU-35, H3BTB = 4′,4′′,4′′′-benzene-1,3,5-tribenzoic acid) and {[(CH3)2NH2][Mg2(FDA)2(Ac)]}n (SNNU-36, H2FDA = 2,5-furandicarboxylic acid) were successfully designed, which crystallize in rhombohedral R-3 and tetragonal I4/mmm space groups, respectively. Four independent BTB ligands link three unique Mg cations and generate superlarge [Mg21BTB17] nanocages, which interlock each other by strong π···π stacking to give a two-fold interpenetrating architecture of SNNU-35. On the other hand, carboxylate and acetate groups chelate Mg atoms to form one-dimensional chains, which are extended by FDA to produce the rod-packing framework of SNNU-36. Two microporous Mg-MOFs both exhibit notable CO2 and H2 uptakes. H3BTB and H2FDA ligands both have emission features, and Mg ions usually can enhance the fluorescent intensity, which lead to a strong solid-state luminescence emission property of SNNU-35 and -36. Importantly, two Mg-MOFs both show fast and quantative sensing performance for nitrocompounds. Among three selected models of substrate, SNNU-35 and -36 can eliminate the interference of nitromethane (NM) and exhibit high sensitivity to nitrobenzene (NB) and o-nitrotoluene (2-NT) with large ksv values (>105 M?1). Especially, the fluorescence quenching efficiency of NB (5000 ppm) and 2-NT (8000 ppm) can reach 96.3% and 89.5% and 85.0% and 83.7% for SNNU-35 and -36, respectively. This work offers not only an effective route to improve the symmetry of magnesium-organic frameworks but also two potential fluorescence sensors for nitroaromatic compounds.
关键词： magnesium-organic frameworks,nitrocompounds,fluorescence sensing,modulator,acetate
更新于2025-09-23 15:21:01