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排序方式: 共有3462条查询结果,搜索用时 17 毫秒
1.
《Mendeleev Communications》2022,32(5):691-692
Thermodynamic characteristics of a single crystal of bismuth orthogermanate (Bi4Ge3O12), which are necessary to improve device portfolio, have been studied. It has been shown that bismuth orthogermanate is thermodynamically stable against decomposition into binary oxides at 50 °C, which gives us grounds to consider this compound promising for various applications. 相似文献
2.
《Arabian Journal of Chemistry》2022,15(6):103783
This study reports a deep eutectic solvent based dispersive liquid-liquid microextraction (DES-DLLME) to extract aromatic amines (4-chloroaniline, 3-nitroaniline, 2-naphtylamine) in environmental water samples before their HPLC-UV determination. The hydrophobic deep eutectic solvent (DES) was prepared by mixing bis(2-ethylhexyl) phosphate (BEHP) as a hydrogen bond acceptor and phenol as a hydrogen bond donor. Affecting factors on the extraction of the aromatic amines were investigated and optimized. Optimum conditions were: DES type: BHHP-Ph ratio: 1 to 2; pH of solution: 8.0; DES volume: 80 µL, salt amount: 10% (w/v). Under optimum conditions, the developed method showed a wide linear range of 0.2–200 µg L?1 (R2 ≥ 0.99) with satisfactory recoveries (≥90.0%). The limit of detections (LODs) and limit of quantifications (LOQs) were in the range of 0.07–0.17 µg L?1 and 0.2–0.5 µg L?1, respectively. The enrichment factors were 170, 180 and 190 for 4-chloroaninile, 3-nitroaniline, 2-naphtylamine, respectively. Based on obtained results, the proposed method is straightforward, efficient, sensitive, and eco-friendly for the extracting and determining of the aromatic amines in environmental water samples. 相似文献
3.
采用铜/锌复合金属磷酸盐晶体和海藻酸钙凝胶双重包覆技术对漆酶进行固定化, 制得石榴状Alg@Cu3/Zn3(PO4)2@Lac的凝胶微球. SEM, EDX和FTIR表征结果表明, 在凝胶微球内部, 漆酶被成功固定于由海藻酸钙凝胶包覆的铜/锌复合金属磷酸盐晶体内, 铜/锌复合金属磷酸盐晶体镶嵌于海藻酸钙凝胶网格的孔隙中而呈石榴状. 以2,2′-联氮双(3-乙基苯并噻唑啉-6-磺酸)(ABTS)为底物, 经酶学性质研究表明, 在无机盐晶体和海藻酸钙凝胶的双重保护下, Alg@Cu3/Zn3(PO4)2@Lac的耐热性、 耐酸性以及储存稳定性比游离漆酶均有不同程度增强. 将Alg@Cu3/Zn3(PO4)2@Lac应用于双酚A(BPA)的降解, 采用孔径约1 mm滤网实现快速回收, 经6次循环利用, 对BPA的降解率下降约14%, 显示出比较稳定的重复利用性和便捷的可操作性, 这主要得益于海藻酸钙和铜/锌无机盐晶体对漆酶蛋白分子的双重保护. 相似文献
4.
Jingyi Kang Na Chang Feifei Wang Haixia Liu Xuemei Wang Xinzhen Du 《Journal of separation science》2022,45(6):1273-1281
A novel solid-phase microextraction coating of phosphorous-containing titanium oxide composite was developed using titanium fiber as a support and a titanium source by hydrothermal oxidation in a phosphoric acid solution containing hydrogen peroxide. The morphology of the fiber coatings was controlled by the conditions of the hydrothermal oxidation reaction. The oriented nanofiber coating was employed to extract several types of representative aromatic analytes. The experimental results demonstrated that the as-prepared fiber exhibited excellent extraction efficiency toward polycyclic aromatic hydrocarbons. Combined with high-performance liquid chromatography with ultraviolet detection, main extraction conditions were optimized, including pH, ionic strength, extraction temperature, stirring rate, extraction time and desorption time. The established method presented good linearity from 0.05 to 200 μg/L with limit of detection ranging from 0.012 to 0.126 μg/L. This convenient and green procedure was suitable for the selective extraction and determination of typical polycyclic aromatic hydrocarbons in environmental water samples. The relative recoveries of 85.8–112% were obtained for the determination of target polycyclic aromatic hydrocarbons in water samples spiked with 5.0 and 15.0 μg/L. Moreover, the as-prepared fiber showed at least 210 extraction/desorption cycles due to its high mechanical and chemical stability. 相似文献
5.
《Arabian Journal of Chemistry》2022,15(4):103712
Although recent decades have witnessed the synthesis of 1,3,4-thiadiazoles via phosphorus POCl3-promoted cyclization reaction, simultaneous access to 2-amino-1,3,4-thiadiazole and 2-amino-1,3,4-oxadiazole analogs remains unexpected and elusive. Herein, a detailed regiocontrolled synthesis of 2-amino-1,3,4-thiadiazoles in good to high yields with good regioselectivities from readily available thiosemicarbazides using POCl3 was disclosed. Meantime, to establish a comprehensive structure–activity relationship, 2-amino-1,3,4-oxadiazole derivatives as single regioisomers were prepared via EDCI·HCl-triggered cyclization of the thiosemicarbazide intermediates. The in vitro anti-influenza assays proved that the selected compounds with the pyrazine/pyridine ring exhibited certain inhibitory activities against influenza A virus strains A/HK/68 (H3N2) and A/PR/8/34 (H1N1) in MDCK cells. Among them, N-(adamantan-1-yl)-5-(5-(azepan-1-yl)pyrazin-2-yl)-1,3,4-thiadiazol-2-amine (4j) was the most active compound, and exhibited favorable activity with EC50 values of 3.5 μM and 7.5 μM, respectively. In addition, the molecular docking results explained the reason why compound 4j had dual inhibitory activity and revealed the reasonable binding mode of this compound with the M2-S31N and M2-WT ion channels. This compound had the potential to be further developed as an anti-influenza drug. 相似文献
6.
以轻烧白云石粉、氯化铵和二氧化碳为原料,在未使用晶型控制剂的情况下,通过蒸氨-沉钙过程制备出了似立方体状碳酸钙。研究了反应温度、溶液中钙离子浓度、通气速率、搅拌速度以及陈化时间对碳酸钙中方解石相含量以及晶体形貌的影响,并探索了沉钙反应的晶型控制机理。结果表明,在反应温度40 ℃、钙离子浓度0.05 mol/L、通碳速率100 mL/min、搅拌速度400 r/min和陈化时间2 h的条件下,制备出形貌规整、粒径分布均匀的似立方体状碳酸钙,平均粒径为5~10 μm。该研究为提升白云石的使用价值、生产高附加价值的碳酸钙产品,以及提高白云石资源的利用率提供理论基础。 相似文献
7.
Annija Lace Aideen Byrne Simon Bluett Laurent Malaquin Vincent Raimbault Remi Courson Zain Hayat Breda Moore Eoin Murray 《Journal of separation science》2022,45(5):1042-1050
An ion chromatography system employing a low-cost three-dimensional printed absorbance detector for indirect ultraviolet detection towards portable phosphate analysis of environmental and industrial waters has been developed. The optical detection cell was fabricated using stereolithography three-dimensional printing of nanocomposite material. Chromatographic analysis and detection of phosphate were carried out using a CS5A 4 × 250 mm analytical column with indirect ultraviolet detection using a 255 nm light-emitting diode. Isocratic elution using a 0.6 mM potassium phthalate eluent combined with 1.44 mM sodium bicarbonate was employed at a flow rate of 0.75 mL/min. A linear calibration range of 0.5 to 30 mg/L PO43− applicable to environmental and wastewater analysis was achieved. For retention time and peak area repeatability, relative standard deviation values were 0.68 and 4.09%, respectively. Environmental and wastewater samples were analyzed with the optimized ion chromatography platform and the results were compared to values obtained by an accredited ion chromatograph. For the analysis of environmental samples, relative errors of <14 % were achieved. Recovery analysis was also carried out on both freshwater and wastewater samples and recovery results were within the acceptable range for water analysis using standard ion chromatography methods. 相似文献
8.
Sergey I. Lopatin Sergey M. Shugurov Andrej I. Panin 《Journal of mass spectrometry : JMS》2019,54(6):507-519
Gaseous CePO2 has been identified by Knudsen effusion mass spectrometry during vaporization of CeO2 and magnesium diphosphate from tungsten double, two‐temperature effusion cell. Structure and molecular parameters of gaseous cerium phosphate under study were determined using quantum chemical calculations. On the basis of equilibrium constants measured for gas‐phase reaction, standard formation enthalpy of CePO2 was determined to be ?508 ± 41 kJ ? mol?1 at the temperature 298 K. 相似文献
9.
韩晓 《中国无机分析化学》2019,9(2):54-57
试样用盐酸、硝酸、氢氟酸、高氯酸分解,在pH值为6~9时,经六次甲基四胺-铜试剂分离铁、铝、镍、钴、铅、锌、铜、镉、锰等干扰元素后,在pH=10的氨水和氯化铵缓冲溶液中,以酸性铬蓝K-萘酚绿B为指示剂,用EDTA络合滴定法测定钙镁合量;另在氢氧化钾溶液中,用钙试剂为指示剂,以EDTA络合滴定法测定钙量,从而计算镁的含量。当样品钙高镁低或者镁高钙低时,低含量的镁量或钙量(5%)可用电感耦合等离子体原子发射光谱(ICP-AES)法准确测定,使结果更准确。实验中对三个标准样品中的钙和镁进行多次测定,结果与认定值相符,相对标准偏差在0.69%~1.3%(n=7),加标回收率在99%~102%。方法实用性强,已经成功应用于各类矿石中钙镁的检测。 相似文献
10.
Laila SADALLAH Aicha BOUKHRIS Hassan HANNACHE Said GMOUH 《Turkish Journal of Chemistry》2020,44(1):142
Two organic fluorophores, fluorescein (F) and rhodamine B (Rd), were entrapped in calcium phosphate nanoparticles. The as-obtained nanoparticles can be used for biological release applications. For this aim, calcium phosphate nanoparticles were synthesized using the precipitation method. Structural analysis of these nanoparticles was performed using XRD, FTIR, and Raman spectroscopy, confirming that the synthesized nanoparticles were hydroxyapatite. TEM and SEM analyses demonstrated that these nanoparticles had a size of 20 nm and a well-defined morphology. F and Rd (about 0.5 wt.%) were entrapped in these nanoparticles and their release, as a function of time, was studied via UV-Vis spectroscopy. The obtained results showed that the release of both fluorophores was progressive over time. The trapping efficiencies of the fluorophores were 67.15% and 90.76% for F and Rd, respectively. 相似文献