8 results on '"Si-Wen Gu"'
Search Results
2. Structure and property of PFSA/PES porous catalytic nanofibers
- Author
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Xiao-Hua Ma, Zhen-Liang Xu, and Si-Wen Gu
- Subjects
chemistry.chemical_classification ,Materials science ,Nanotechnology ,02 engineering and technology ,General Chemistry ,Sulfonic acid ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Catalysis ,Electrospinning ,0104 chemical sciences ,Chemical kinetics ,chemistry ,Chemical engineering ,Nanofiber ,Specific surface area ,0210 nano-technology ,Mesoporous material ,Porosity - Abstract
Perfluorinated sulfonic acid (PFSA)/polyether sulfone (PES) porous catalytic nanofiber was fabricated and applied to esterification reaction as catalyst in this work. To this aim, PES porous nanofibers were firstly prepared through electrospinning, and PFSA resin as catalyst was successfully anchored on these PES porous nanofibers through dip-coating method. Mesoporous structure was observed in PES porous nanofibers with high specific surface area of 40.6 m 2 /g. The catalytic properties of PFSA/PES porous catalytic nanofibers were measured by esterification of ethanol and acetic acid as model reaction. The recovery of PFSA/PES porous catalytic nanofibers remained 93.8% after three cycles of esterification, and the ion exchange capacity almost remained at a constant level, showing excellent recovery. For PFSA/PES porous catalytic nanofibers loaded with 5 wt% of PFSA as catalyst, the conversion rate and forward reaction kinetics constant achieved 85.8% at 1 h and 9.03 × 10 −4 m 3 kmol −1 s −1 g −1 , respectively.
- Published
- 2016
3. Process optimization and modeling of membrane reactor using self-sufficient catalysis and separation of difunctional ceramic composite membrane to produce methyl laurate
- Author
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Zhen-Liang Xu, Xiao-Hua Ma, Xin Wen, Si-Wen Gu, Yue Cao, and Hui-Xin Zhang
- Subjects
Aqueous solution ,Materials science ,Membrane reactor ,technology, industry, and agriculture ,Filtration and Separation ,Lauric acid ,Analytical Chemistry ,Catalysis ,chemistry.chemical_compound ,Membrane ,chemistry ,Chemical engineering ,Specific surface area ,Polymer chemistry ,Methanol ,Pervaporation - Abstract
Difunctional hollow fiber ceramic composite membranes with self-sufficient catalysis and separation properties were successfully fabricated through thermal imidization, followed by dip-coating method. The structure, separation and catalysis properties of the fabricated difunctional membrane were investigated by SEM, pervaporation dehydration of methanol aqueous solution, and esterification of methanol and lauric acid to produce methyl laurate in a membrane reactor, respectively. The results showed that the obtained difunctional membrane was characterized by a multilayer structure: a sponge-like support layer, a dense separation layer and a porous catalysis layer. The porous catalysis layer had little effect on separation property. But it provided a large specific surface area for perfluorosulfonic acid (PFSA), resulting in a good catalytic effect. The obtained difunctional membrane also showed an excellent stability and repeatability. The optimized operating conditions were methanol to lauric acid ratio of 10:1, reaction temperature of 70 °C, and catalyst dosage of 1.0 wt% in this work. A mathematical model was established to describe this experimental process and the predicted results agreed well with the experimental results.
- Published
- 2014
4. Risk-factor model for postpartum hemorrhage after cesarean delivery: a retrospective study based on 3498 patients
- Author
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Jun Gong, Zhi Chen, Yi Zhang, Yi-yun Liu, Jun-cai Pu, Chun-yan Xiong, Si-wen Gui, Xiao-ling He, Hui-lai Wang, and Xiao-gang Zhong
- Subjects
Medicine ,Science - Abstract
Abstract This study aimed to investigate the risk factors of patients with postpartum hemorrhage (PPH) after cesarean delivery (CD) and to develop a risk-factor model for PPH after CD. Patients were selected from seven affiliated medical institutions of Chongqing Medical University from January 1st, 2015, to January 1st, 2020. Continuous and categorical variables were obtained from the hospital’s electronic medical record systems. Independent risk factors were identified by univariate analysis, least absolute shrinkage and selection operator and logistic regression. Furthermore, logistic, extreme gradient boosting, random forest, classification and regression trees, as well as an artificial neural network, were used to build the risk-factor model. A total of 701 PPH cases after CD and 2797 cases of CD without PPH met the inclusion criteria. Univariate analysis screened 28 differential indices. Multi-variable analysis screened 10 risk factors, including placenta previa, gestational age, prothrombin time, thrombin time, fibrinogen, anemia before delivery, placenta accreta, uterine atony, placental abruption and pregnancy with uterine fibroids. Areas under the curve by random forest for the training and test sets were 0.957 and 0.893, respectively. The F1 scores in the random forest training and test sets were 0.708. In conclusion, the risk factors for PPH after CD were identified, and a relatively stable risk-factor model was built.
- Published
- 2022
- Full Text
- View/download PDF
5. Preparation and characterization of catalytic TiO2–SPPESK–PES nanocomposite membranes and kinetics analysis in esterification
- Author
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Xin Wen, Jin-Long Zhang, Zhen-Liang Xu, Xiao-Hua Ma, and Si-Wen Gu
- Subjects
chemistry.chemical_classification ,Nanocomposite ,Kinetics ,Filtration and Separation ,Polymer ,Biochemistry ,Catalysis ,Sulfone ,chemistry.chemical_compound ,Membrane ,chemistry ,Chemical engineering ,Specific surface area ,Polymer chemistry ,medicine ,General Materials Science ,Physical and Theoretical Chemistry ,Swelling ,medicine.symptom - Abstract
TiO2–SPPESK–PES nanocomposite membranes were successfully prepared using nano TiO2 to provide a high specific surface area, sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK) with a 60% degree of sulfonation as a catalyst and polyether sulfone (PES) as a polymer support. The pore structure, morphology, water uptake, hydrophilic nature, degree of geometric swelling, mechanical properties and catalytic properties of the nanocomposite membranes were evaluated. A pseudo-homogeneous model was established to describe the kinetics of the esterification of acetic acid with ethanol. The results showed that TiO2–SPPESK–PES nanocomposite membranes had high specific surface areas (33.2–56.0 m2/g), mesopores structures (5–7 nm), good stability (swelling ratio less than 1.7% even at 80 °C), good mechanical strength and high catalytic activity (the conversion of ethanol reached to 82%), and good forward rate constants (6.28×10−3–13.6×10−3 L/(mol min)).
- Published
- 2013
6. Spinnability of SPPESK and its application in esterification
- Author
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Jin-Long Zhang, Zhen-Liang Xu, Xin Wen, Xiao-Hua Ma, and Si-Wen Gu
- Subjects
Materials science ,Polymers and Plastics ,Organic Chemistry ,Ether ,Electrospinning ,Sulfone ,Catalysis ,chemistry.chemical_compound ,Acetic acid ,chemistry ,Chemical engineering ,Nanofiber ,Specific surface area ,Polymer chemistry ,Materials Chemistry ,Fourier transform infrared spectroscopy - Abstract
The electrospinning of sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK) and its blend with polyether sulfone (PES) were investigated and the blend nanofibers were applied as a catalyst in esterification. Attempts to electrospin pure SPPESK resulted in electrospraying rather than electrospinning. However, a blend polymer solution of SPPESK and PES resulted in smooth electrospinning when SPPESK content was lower than 9 wt%. The geometrical properties such as fiber diameter and distribution, surface chemical properties such as inter-molecular interaction and crystalline, mechanical properties were investigated by SEM, FTIR, XRD, etc. The catalytic activities of SPPESK-PES nanofibers were measured by esterification of ethanol with acetic acid. A pseudo-homogeneous model was established to describe the kinetics of esterification with nanofiber as a catalyst. The results showed that the SPPESK-PES blend nanofiber had a high specific surface area (46.7–58.9 m2/g), good mechanical properties, good catalytic properties (ethanol conversion up to 80 % when reacted 8 h), and good forward rate constants (10.0 × 10−3–14.6 × 10−3 L/(mol∙min)).
- Published
- 2013
7. Social defeat stress causes depression-like behavior with metabolite changes in the prefrontal cortex of rats.
- Author
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Yi-Yun Liu, Xin-Yu Zhou, Li-Ning Yang, Hai-Yang Wang, Yu-Qing Zhang, Jun-Cai Pu, Lan-Xiang Liu, Si-Wen Gui, Li Zeng, Jian-Jun Chen, Chan-Juan Zhou, and Peng Xie
- Subjects
Medicine ,Science - Abstract
Major depressive disorder is a serious mental disorder with high morbidity and mortality. The role of social stress in the development of depression remains unclear. Here, we used the social defeat stress paradigm to induce depression-like behavior in rats, then evaluated the behavior of the rats and measured metabolic changes in the prefrontal cortex using gas chromatography-mass spectrometry. Within the first week after the social defeat procedure, the sucrose preference test (SPT), open field test (OFT), elevated plus maze (EPM) and forced swim test (FST) were conducted to examine the depressive-like and anxiety-like behaviors. For our metabolite analysis, multivariate statistics were applied to observe the distribution of all samples and to differentiate the socially defeated group from the control group. Ingenuity pathway analysis was used to find the potential relationships among the differential metabolites. In the OFT and EPM, there were no significant differences between the two experimental groups. In the SPT and FST, socially defeated rats showed less sucrose intake and longer immobility time compared with control rats. Metabolic profiling identified 25 significant variables with good predictability. Ingenuity pathways analysis revealed that "Hereditary Disorder, Neurological Disease, Lipid Metabolism" was the most significantly altered network. Stress-induced alterations of low molecular weight metabolites were observed in the prefrontal cortex of rats. Particularly, lipid metabolism, amino acid metabolism, and energy metabolism were significantly perturbed. The results of this study suggest that repeated social defeat can lead to metabolic changes and depression-like behavior in rats.
- Published
- 2017
- Full Text
- View/download PDF
8. Process optimization and modeling of membrane reactor using self-sufficient catalysis and separation of difunctional ceramic composite membrane to produce methyl laurate.
- Author
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Xiao-Hua Ma, Hui-Xin Zhang, Si-Wen Gu, Yue Cao, Xin Wen, and Zhen-Liang Xu
- Subjects
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PROCESS optimization , *MEMBRANE reactors , *CATALYSIS , *SEPARATION (Technology) , *COMPOSITE membranes (Chemistry) , *CERAMICS , *HOLLOW fibers - Abstract
Difunctional hollow fiber ceramic composite membranes with self-sufficient catalysis and separation properties were successfully fabricated through thermal imidization, followed by dip-coating method. The structure, separation and catalysis properties of the fabricated difunctional membrane were investigated by SEM, pervaporation dehydration of methanol aqueous solution, and esterification of methanol and lauric acid to produce methyl laurate in a membrane reactor, respectively. The results showed that the obtained difunctional membrane was characterized by a multilayer structure: a sponge-like support layer, a dense separation layer and a porous catalysis layer. The porous catalysis layer had little effect on separation property. But it provided a large specific surface area for perfluorosulfonic acid (PFSA), resulting in a good catalytic effect. The obtained difunctional membrane also showed an excellent stability and repeatability. The optimized operating conditions were methanol to lauric acid ratio of 10:1, reaction temperature of 70 °C, and catalyst dosage of 1.0 wt% in this work. A mathematical model was established to describe this experimental process and the predicted results agreed well with the experimental results. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
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