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Novel solid polymer electrolyte based on PMMA:CH3COOLi effect of salt concentration on optical and conductivity studies
摘要： Novel solid polymer electrolyte (SPE) films based on poly(methyl methacrylate) (PMMA) and lithium acetate (CH3COOLi) with different weight ratios of PMMA:CH3COOLi wt% (60:40, 70:30, 80:20 wt%) were prepared by solution casting technique. XRD analysis confirmed the amorphous nature of Li–PMMA SPE films. FTIR analysis revealed the structural changes in polymer by complexation with Li salt. From the optical absorbance studies, the value of lowest energy band gap was found to be 3.06 eV for the composition, PMMA:CH3COOLi (60:40 wt%). From AC impedance studies, the highest value of ionic conductivity 8.21 × 10?5 S/cm at 303 K for the SPE film PMMA:CH3COOLi (60:40 wt%) is observed compared to the reported literature. From the results of Li–PMMA SPE film with high ionic conductivity, it is a promising material for the application of solid-state battery.
关键词： Band gap,Ionic conductivity,Dielectric measurements,Li–PMMA SPE
更新于2025-09-23 15:23:52
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Optical properties of soil DOM are related to acidic functions of its components as revealed by fractionation, selective deuteromethylation and ultra-high resolution mass spectrometry
摘要： The goal of this study was to establish relationship between the optical properties of soil dissolved organic matter (DOM) and acidic functions carried by its individual constituents. We obtained twelve fractions of DOM samples using sequential solid phase extraction on nonionic sorbent at steadily lowered pH values: 7, 5, 3, 2, which correspond to low bounds of pKa values of phenols, aliphatic and aromatic carboxylic acids and ketoacids. The structural studies were conducted with a use of NMR and selective deuteromethylation of isolated fractions coupled to ultra-high resolution mass spectrometry. First, a gradual shift of molecular compositions was observed from reduced components to aromatic oxidized compounds isolated at pH7 and 2, respectively. Changes in molecular compositions were accompanied by a red shift of fluorescence spectra. Further application of deuteromethylation enabled to distinguish DOM constituents with different amount of carboxylic groups. Moreover, identification of structural isomers in a single DOM sample was achieved. Statistical analysis revealed that red shift of fluorescence is facilitated by the increase of a contribution of aromatic polycarboxylic acids with high conjugation lengths. Additionally, analysis of the labeled fractionated permafrost thaw DOM directly showed carboxyl-rich alicyclic molecules, while same components from lower-latitude DOM were assigned to lignin-like species.
关键词： DOM,structure,separation,acidity,fluorescence,SPE extraction,isotopic labeling,FTICR MS
更新于2025-09-19 17:13:59
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Setup of a photomultiplier tube test bench for LHAASO-KM2A
摘要： To ful(cid:12)ll the requirements for testing the photomultiplier tubes (PMTs) of the electromagnetic detector at the Large High Altitude Air Shower Observatory (LHAASO), a multi-functional PMT test bench with a two-dimensional scanning system has been developed. With this 2D scanning system, 16 PMTs can be scanned simultaneously for characteristics tests, including uniformity, cathode transit time di(cid:11)erence, single photo-electron spectrum, gain vs. high voltage, linear behavior and dark noise. The programmable hardware and intelligent software of the test bench make it convenient to use and provide reliable results. The test methods are described in detail and primary results are presented.
关键词： TTS,PMTs,cathode uniformity,LHAASO,CTTD,SPE spectrum,KM2A
更新于2025-09-11 14:15:04
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Exploring aggregation-induced emission through tuning of ligand structure for picomolar detection of pyrene
摘要： Tuning of ligand structures through controlled variation of ring number in fused‐ring aromatic moiety appended to antipyrine allows detection of 7.8 × 10?12 M pyrene via aggregation‐induced emission (AIE) associated with 101‐fold fluorescence enhancement. In one case, antipyrine unit is replaced by pyridine to derive bis‐methylanthracenyl picolyl amine. The structures of four molecules have been confirmed by single crystal X‐ray diffraction analysis. Among them, pyrene‐antipyrine conjugate (L) undergoes pyrene triggered inhibition of photo‐induced electron transfer (PET) leading to water‐assisted AIE.
关键词： pyrene,AIE,sensor,SPE,SC‐XRD
更新于2025-09-10 09:29:36
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Benzimidazoles in wastewater: Analytical method development, monitoring and degradation by photolysis and ozonation
摘要： Pharmaceutical residues are constantly released into natural waters, mainly from wastewater treatment plants (WWTPs) whose processes are unable to completely eliminate them. Among these drugs, the occurrence of benzimidazoles, a class of antiparasitics for human and veterinary use, has been reported in WWTP e?uents and surface waters. In this study, an SPE-UHPLC-MS/MS method was developed and optimized for extraction and quantitation of benzimidazoles in in?uents and e?uents of a local WWTP and in hospital wastewater. The extraction procedure was optimized using response surface methodology (Box-Behnken design) and the optimal parameters were as follows: 2.0 mL of loading solvent consisting of a mixture of water:methanol (95:5, v/v) and temperature at 43 °C. In hospital wastewater, albendazole (ABZ) and its principal metabolite ricobendazole (RBZ) were the main benzimidazole-related contaminants and were found at concentrations of up to 3810 and 3894 ng L?1, respectively. The WWTP system was able to remove from 46% to 95% of the ABZ quanti?ed in the in?uent, discharging an e?uent with 16–441 ng L?1 of ABZ. The concentrations of other benzimidazoles and metabolites in the WWTP e?uents remained below 350 ng L?1. WWTP e?uents forti?ed with 50 μg L?1 of ABZ and RBZ required 26.7 mgO3 L?1 to remove ABZ and RBZ. After ozonation, the COD and BOD5 of the e?uents were reduced by 27%. Photolysis by UVA radiation was not e?ective to remove ABZ and FBZ from the e?uent samples.
关键词： Antiparasitic,Online SPE-UHPLC-MS/MS,Box-Behnken design,Pharmaceutical residue,Albendazole
更新于2025-09-04 15:30:14