Journal of Chemistry
·
2013
·Vol. 2013
·期 1
·791437
·
IF 0
Lai-Jun Zhang,Fa-Yun Chen,Ji-Zao Tong,Guang-Da Chen,Hai-Jin Huang,Xing-Can Shen
Zinc selenide (ZnSe) nanocrystals were synthesized via a phosphine-free route using the highly reactive alkylamine-H 2 Se complex as selenium precursor and zinc precursors with different reactivity. The reactivity of zinc precursor was tuned by using three kinds of zinc carboxylates with different alkyl chain lengths, including zinc acetate, zinc nonanoate, and zinc stearate. The effect of the reactivity and the amount of zinc precursor on nucleation and growth of ZnSe nanocrystals were investigated by ultraviolet-visible absorption and photoluminescence spectra. Result indicates that the growth and optical property of the resulting ZnSe nanocrystals are strongly dependent on the alkyl chain length and the amount of the zinc carboxylates and both shorter alkyl chain length, and more amount of zinc carboxylate will lead to faster growth of ZnSe nanocrystals. This allows that the controlled growth and excellent optical property of high-quality ZnSe nanocrystals can be achieved by combining the different reactivity and the used amount of zinc precursor, such as by using stoichiometric and reactive Zn precursor and Se precursor or by using larger amount of more unreactive Zn precursor relative to the highly reactive alkylamine-H 2 Se complex precursor.
研究领域:
材料科学
·
纳米技术
✓ 已验证
DOI
ENVIRONMENTAL GEOCHEMISTRY AND HEALTH
·
2025
·Vol. 48
·期 1
·24
·
IF 3.8
Wang Bin,Yao Yiming,Sun Hongwen,Zhao Hongyan,Yu Qingxia
Wastewater treatment plants (WWTPs) and landfill represent critical point sources for per- and polyfluoroalkyl substance (PFAS) emission to the atmosphere. This study aimed to (1) quantitatively characterize both neutral and ionizable PFAS in air samples from these sources, and (2) estimate the potential emission contributions of unknown PFAS precursors. Using an optimized cartridge-based active air sampler, we collected atmospheric samples from a WWTP and landfill in Tianjin, China. Quantitative analysis revealed comparable concentration ranges for neutral (Σn-PFAS: 2,816–564,343 pg/m 3 ) were higher than ionizable PFAS (Σi-PFAS: 4,275–13,360 pg/m 3 ), with 8:2 fluorotelomer alcohol (8:2 FTOH; 2,273–13,360 pg/m 3 ) dominating neutral species and trifluoroacetic acid (TFA; 2,490–10,575 pg/m 3 ) prevailing among ionizable compounds. The total oxidizable precursor assay demonstrated that unknown precursors accounted 46.4–58.4 mol% of total PFAS. These findings provide the quantitative evidence of airborne PFAS speciation and associated unknown precursor-derived emission contributions in the WWTP and landfill.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MOLECULES
·
2019
·Vol. 24
·期 8
·1474
·
IF 3.06
Kai Zhou,Lorenzo Siroli,Francesca Patrignani,Yuanming Sun,Rosalba Lanciotti,Zhenlin Xu
The aim of this work was to clarify the formation of ethyl carbamate (EC) and its influence factors throughout the production process of Cantonese soy sauce. The results showed that EC was not detected in thekoji-making and earlymoromifermentation stages, but started to be generated when pH of themoromidecreased to about 4.9—at the same time, the levels of ethanol, urea and citrulline increased significantly. Most EC was formed during raw soy sauce hot extraction (40.6%) and sterilization (42.9%) stages. The EC content exhibited the highest correlation with ethanol throughout the whole production process (R = 0.97). The simulation soy sauce produced in laboratory led the same conclusion—moreover, the contents of EC, ethanol and citrulline were higher in soy sauce fermented at 30 °C than in soy sauce fermented at 15 °C. Extraction of raw soy sauce by squeezing contributed little to EC formation. Further research showed that citrulline and ethanol led to significant increases in EC levels in raw soy sauce upon heating. These results indicate that ethanol and citrulline are two critical precursors of EC and that EC is mainly formed during the heat treatment stage of soy sauce.Keywords:ethyl carbamate;soy sauce;precursor;ethanol;accumulation stage
研究领域:
食品科学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF PHARMACEUTICAL SCIENCES
·
2023
·
IF 3.8
Wenxuan Cao,Jingbao Chen,Long Wu,Yu hang Xu,Yun Meng,Xiang Li,Zhiyun Zheng,Xiaoqin Chu
Purpose The aim of this study was to develop liquid crystal (LC) precursors to obtain novel long-acting analgesics for injection based on depot systems and compare the difference between the cubic and hexagonal precursors in delivering Diclofenac sodium (DS). Methods Diclofenac sodium liquid crystal precursor injections were prepared and characterized, followed by in vitro release, pharmacodynamic , and pharmacokinetic studies. Results The optimal formulations were prepared with a ratio of Phytantriol/ethanol/water as 76:19:5 for cubic LC precursors, and a ratio of Phytantriol/ethanol/water/Vitamine-E acetate as 72:18:5:5 for hexagonal, both loading various drug dosages (2.5%, 3.75% and 5%), respectively. Polarized light microscopy and small angle diffraction confirmed that the precursors were isotropic fluids and transformed into gels with Pn3m or HII framework in water. Rheological studies have shown that precursors belong to Newtonian fluids and gels to pseudoplastic fluids. The release showed that the DS in the commercial injection (DS-inj) was completely liberated within 6 h, whereas only 46.55% and 49.73% of the DS in 2.5% cubic precursors and 2.5% hexagonal precursors were freed, respectively. Pharmacodynamic studies have shown that cubic, hexagonal and DS-inj raised the pain threshold in mice by 169.4%, 157.3% and 113.79%, respectively. The mean retention times of DS in cubic and hexagonal were 3.16 and 2.67 times longer than DS-inj, respectively, according to pharmacokinetic results. Conclusion In conclusion, cubic and hexagonal are both promising analgesic sustained release formulations. In addition, based only on the current comparison, cubic seems to have a better long-acting effect.
研究领域:
药剂学
·
药物递送系统
·
药理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Ne Ni,Ying Ouyang,Jianqiang Liu,Enhui Xing,Yibin Luo,Xingtian Shu
It was the thermostability and acidity of P precursors that influenced the interaction between P species and framework Al to determine the hydrothermal stability of P modified ZSM-5. With H3PO2 and NH4H2PO2 as P precursors, the P–Al interactions of P modified ZSM-5 samples calcined under different temperatures were systematically investigated by X-ray fluorescence, X-ray photoelectron spectroscopy, 27Al, and 31P MAS NMR spectroscopy, and temperature-programmed desorption of NH3 (NH3-TPD). With H3PO2 as the precursor, lower calcination temperature favored less self-polymerization of P species; however, obvious loss of phosphorus was observed during hydrothermal treatment. Conversely, higher calcination temperature tended to result in excessive interaction between P and framework Al for dealumination. Therefore, moderate interactions between P and framework Al were obtained over H3PO2 modified ZSM-5 calcined at 350 °C, which contributed to weaken the self-polymerization of P species. Compared with H3PO2, neutral NH4H2PO2 generated a relatively weaker P-zeolite interaction, which was less affected by the calcination temperature.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
Thermal Science and Engineering Progress
·
2023
·
IF 4.8
Shuai Guo,Guoliang Qi,Jialiang Gao,Deng Zhao,Kaixin Chen,Chenchen Zhao,Xingcan Li,Guangyu Li
Pyrolysis is an effective method for safely disposing of sewage sludge via conversion into a usable energy source. However, municipal sludge has a high protein content, which is a major source of NO x precursors. This study investigated the effect of CaO on NO x precursor formation during glutamate pyrolysis and demonstrated that CaO occupies the carbo x yl site of glutamic acid at 320 °C, which delays its decomposition and promotes the conversion of glutamic acid from a five- to a si x -membered ring. At 400 °C, heterocyclic nitrogen in the tar peaked from 4.87 to 53.87% after adding CaO. As the temperature increases to 480 °C, CaO might promote the conversion of heterocyclic nitrogen into tricyclic piperazine dione in the tar, which subsequently decomposed to produce HCN in large quantities. At 480 °C, CaO contributed to the decrease in pyrrole, pyridine, and quaternary nitrogen in the semi-coke from 24.81%, 12.93%, and 7.43% to 1.91%, 5.97%, and 1.43%, respectively and promoted HCN hydrolysis to form NH 3 . At 480–680 °C, CaO interacted with NH 3 to form CaCN 2 . The product of CaC x N y decomposition—CaC x —captured NH 3 . At high temperatures, CaO inhibited HCN release, which might be related to the reaction between CaO and HCN to form CaC x N y , subsequently reconverted into CaO at temperatures above 680 °C. These findings provide novel insights into the influence of CaO on amino acid pyrolysis to produce NO x precursors and the regulation of NO x precursor production.
研究领域:
环境科学
·
能源与燃料
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Jiangtao Meng,Jing Wang,Fengling Yang,Fangqin Cheng
This study proposed a novel strategy to control nitrogen oxides (NOx) precursors by directing nitrogen to adhere to the fuel-N→NH 3 →N 2 pathway. The research aimed to illuminate the regulatory effects of CaO, Fe 2 O 3 , and their mixtures on NO and N 2 O precursors (NH 3 , HCN, and HNCO) during sludge pyrolysis, further sought to establish scientific correlations with varying temperatures and differentiate their impact. The findings indicated that unlike NH 3 , HNCO is generated from the cleavage of amides, sharing its origin with HCN. Notably, the sensitivities of three conditioners to different functional groups result in distinct impacts on precursor emissions. CaO interacted with –OH and N-H functional groups, releasing NH 3 . Fe 2 O 3 , being more responsive to C-H and C-C groups, contributed to HNCO emission. At 750 °C, a CaO-Fe 2 O 3 mixture created Ca x Fe y O z , which selectively reacted with N-H and C≡N, facilitating the conversion of HNCO and HCN to NH 3 . While temperature is a crucial factor in the performance of CaO, its impact on Fe 2 O 3 is primarily confined to transformation of heterocyclic and nitrile . Below 350 °C, Fe 2 O 3 favored the evolution of nitrogen into heterocyclic compounds within tar. Conversely, above 490 °C, it inhibited the formation of nitrile in char, promoting the dehydrogenation of tar into unsaturated aromatic structures. The CaO-Fe 2 O 3 mixtures exhibited a superposition of individual effects from CaO and Fe 2 O 3 , with Ca x Fe y O z stimulating N 2 emission. Importantly, among three conditioners, Fe 2 O 3 showed the most significant abatement effect on NOx precursors, primarily through nitrogen fixation in char, nitrogen enrichment in tar, and precursor oxidation. This research contributes innovative perspectives on nitrogen regulation in nitrogen-rich fuels, the utilization of NH 3 , and effective NO and N 2 O control.
研究领域:
环境科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2017
·
IF 3.091
Linlin Yi,Huan Liu,Geng Lu,Qiang Zhang,Jiaxing Wang,Hongyun Hu,Hong Yao
Considerable amounts of NOx are generated from the thermal utilization of solid wastes. To control NOx emission, we investigated the influence of mixed Fe/Ca additives on the generation of NOx precursors (HCN and NH3) during pyrolysis at 873, 1073, and 1273 K. Protein, proline, and phenylalanine were selected as model compounds to represent the primary nitrogen forms in typical solid wastes, such as biomass and sludge. According to the results, the iron effect is a remarkable property that enables the obvious reduction of NH3. This was most likely because NH3 was consumed by iron compounds to generate FeNx. Iron compounds facilitated thermal cracking of heterocyclic N with the release of HCN. Ca(OH)2 promoted the conversion of HCN to NH3 and fixed HCN to form CaCxNy simultaneously. These intermediates (FeNx and CaCxNy) play important roles in the reduction of NOx precursors. A lower emission of NOx precursors was observed with mixed Fe/Ca additives than with either Fe or Ca individually. This is because the generation of Ca2Fe2O5 enhanced the tranformation of intermediates to N2. The transformation of intermediates to N2 was enhanced at elevated temperatures, which allows for the lowest emission of precursors (NH3 and HCN) at 1273 K, with a higher ratio of Ca2Fe2O5 in char.
研究领域:
环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2015
·
IF 4.321
Yingchao Hu,Wenqiang Liu,Jian Sun,Mingkui Li,Xinwei Yang,Yang Zhang,Minghou Xu
A novel inert solid support of Nd 2 O 3 was introduced to enhance the cyclic carbonation/calcination performance of CaO-based sorbents. CaO particles were incorporated into Nd 2 O 3 by a wet-mixing method, using three organometallic precursors (OMPs) as calcium precursors and neodymium(III) acetate hydrate as inert support precursor. For comparison, CaO-based sorbents directly produced from precursors and the naturally occurring sorbent (limestone) were also investigated. FSEM and EDAX results revealed that the ultrafine active specie of CaO particles were homogeneously dispersed into Nd 2 O 3 inert support. As a result, an improved durability and higher carbonation conversion were observed owing to the retarded sintering and the delayed diffusion controlled stage respectively for the sorbents investigated. The performance of the synthetic sorbents also relies on the precursor. When calcium dl -lactate pentahydrate (CaL) was used to incorporate CaO into the inert support Nd 2 O 3 , the highest conversion and best durability were obtained. The effect of calcination temperatures on the sorbent durability was also investigated. Under a relatively severe calcination temperature of 900 °C, a high conversion of about 67% were obtained after 100 carbonation/calcination cycles for a sorbent synthesized from calcium dl -lactate pentahydrate (CaL) and neodymium(III) acetate hydrate. When the calcination temperature was changed to a mild one of 800 °C, a significantly high conversion (>92.5%) was maintained over 100 carbonation/calcination cycles. Besides, no apparent capacity decline was observed for the sorbents after granulation.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Menglan Gao,Xiaobin Liao,Shuting Chen,Xiaoying Li,Yirou Zhang,Chao Chen,Huan Qi
Bromide ion (Br - ) in water sources has been found to affect the formation of carcinogenic non-brominated N-nitrosodimethylamine (NDMA) during ozonation of typical amines. The increasing bromide levels bring more concern due to climate change and industrial discharge, but its effects on actual water matrixes were still unclear. In this study, NDMA formation from three actual water matrixes during ozonation as the Br - concentration increased from 0 to 100 µM were investigated (promotion (100.4 ∼ 231.6 ng/L), promotion then inhibition (399.5 ∼ 461.2 ∼ 428.2 ng/L), and subtle influence (51.9 ± 6.9 ng/L)); from which the NDMA precursors were screened and 8 precursors were selected for exploring the influencing mechanisms. The results indicated that the roles of Br - on NDMA formation significantly depended on the water characteristics of actual matrixes. A total of 16 typical NDMA precursors, which were mainly derived from industrial, agricultural and pharmaceutical sources, were identified. Moreover, 6 brominated substance (Br-DMA, Br-UDMH, Br-DMSC, Br-DMS, Br-TMDS, Br 2 -TMDS), which were thought to play a crucial role in promoting NDMA formation, were also identified in actual water by precursor ion scan (PIS) method. Hypobromous acid (HOBr), which has been proved to be the culprit to the generation of brominated substances, tend to attack the electron-donating groups of amines, such as acylamino (–NHCO-R) or amidogen (–NH 2 ) groups. However, the reactive bromine species (∙Br and ∙Br 2 - ) was inclined to attack the aromatic and anti-oxidant moieties then result in Br - release, as no bromine substitution but free radical transfer reaction occurs. Therefore, decreasing HOBr formation is the crucial step to reduce NDMA generation. This work would provide technical guide for NDMA risks control during ozonation of Br - -amines co-containing water matrixes.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2018
·
IF 3.024
Jin Tan,Chenguang Wang,Qi Zhang,Longlong Ma,Minghong He
A novel and efficient method for the use of non-edible cassava to synthesize biofuel precursors with long carbon chains in two steps was proposed. The finally produced precursors were based on the decomposition of cassava and condensation between furans and levulinates. The reaction parameters for levulinate production from cassava were optimized, and the results showed that the highest carbon mole yield of levulinates was up to 51.3% at 473 K, 4.0 MPa N2, and 6.0 h. After that, precursors with yields of 88.0 and 90.5% could be obtained when the mole ratios between furans and levulinates were 1:1 and 2:1, respectively. Characterization of precursors using elemental analysis, 13C nuclear magnetic resonance, gel permeation chromatography, and Fourier transform infrared spectroscopy demonstrated that different and intersecting routes of condensation resulted in the complex components of precursors. Moreover, the mechanism of condensation was proven to excessively depend upon the mole ratio between furans and levulinates in this investigation. This technical route indicates a simple and feasible method to produce renewable biofuel with long carbon chains from cassava directly.
研究领域:
生物化学
·
可再生能源
·
有机合成
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2024
·Vol. 107
·期 10
·6911-6920
·
IF 3.5
Ruixue Bai,Mian Li,Lingyan Feng,Qing Huang
The family of MAX phases and their two-dimensional derivative MXenes attract significant attention due to their unparalleled properties. Synthesis of MAX phases and MXene from biomass sources is important to expand their biology-related applications, while it remains a challenge. The present work explores the possibility to synthesize MAX phases and subsequently derive MXenes by using biomass precursor. Ti 3 AlC 2 MAX phase was synthesized by using glucose as the carbon source in molten salt. The conversion behavior from glucose to Ti 3 AlC 2 was investigated, and the conversion rate of carbon from glucose reached to 70.4% by optimizing the reaction conditions. The as-obtained Ti 3 AlC 2 can be derived into Ti 3 C 2 T x MXene and MXene quantum dots by common chemical treatments, which provides possibility for biomass-derived nanolaminates applying in biological applications such as biological catalysis, bioinstrumentation, and biological tracking.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）