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An C, Hong W, Jiang X, Sun Y, Li X, Shen F, Zhu T. Catalytic Ozonation of Low Concentration Toluene over MnFeO x-USY Catalyst: Effects of Interactions between Catalytic Components and Introduction of Gas Phase NO x. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024. [PMID: 39088742 DOI: 10.1021/acs.est.4c02050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/03/2024]
Abstract
A series of Mn and Fe metal oxide catalysts loaded onto USY, as well as single metal oxides, were prepared and characterized. The effects of interactions between the catalytic components and the introduction of gas phase NO on the catalytic ozonation of toluene were investigated. Characterization showed that there existed strong interactions between MnOx, FeOx, and USY, which enhanced the content of oxygen vacancies and acid sites of the catalysts and thus boosted the generation of reactive oxygen species and the adsorption of toluene. The MnFeOx-USY catalyst with MnOx and FeOx dimetallic oxides exhibited the most excellent performance of catalytic ozonation of toluene. On the other hand, the presence of NOx in reaction gas mixtures significantly promoted both toluene conversion and mineralization, which was attributed to the formation of nitrate species on the catalysts surface and thus the increase of both acid sites and toluene oxidation sites. Meanwhile, the reaction mechanism between O3 and C7H8 was modified in which the strong interactions between MnOx, FeOx, and USY accelerated the reaction progress based on the L-H route. In addition, the formation of the surface nitrate species not only promoted reaction progress following the L-H route but also resulted in the occurrence of the reaction via the E-R route.
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Affiliation(s)
- Chenguang An
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Wei Hong
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Xinxin Jiang
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Ye Sun
- School of Energy and Power Engineering, Beihang University, Beijing 100191, China
| | - Xiang Li
- School of Energy and Power Engineering, Beihang University, Beijing 100191, China
| | - Fangxia Shen
- School of Energy and Power Engineering, Beihang University, Beijing 100191, China
| | - Tianle Zhu
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
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Zhu Y, Li D, Ji C, Si P, Liu X, Zhang Y, Liu F, Hua L, Han F. Non-Thermal Plasma Incorporated with Cu-Mn/γ-Al2O3 for Mixed Benzene Series VOCs’ Degradation. Catalysts 2023. [DOI: 10.3390/catal13040695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023] Open
Abstract
In this work, a coaxial dielectric barrier discharge (DBD) reactor was constructed to degrade the mixture of toluene and o-xylene, two typical benzene series. The Cu-MnO2/γ-Al2O3 series catalysts prepared by redox and impregnation methods were filled into the plasma device to degrade VOCs synergistically and explore the degradation effect. The experimental results showed that the introduction of a Cu-doped MnO2 catalyst significantly improved the pollutants’ removal efficiency and CO2 selectivity, and greatly inhibited the formation of by-products. Among them, Cu0.15Mn/γ-Al2O3 showed the highest removal efficiency (toluene was 100% and o-xylene was 100%), and the best CO2 selectivity (92.73%). The XRD, BET, XPS and SEM results confirmed that the synergistic effect between Cu and Mn in the Cu-Mn solid solution could promote the amount and reducibility of the surface active oxygen species, which improved the catalytic performance. Finally, the toluene and o-xylene decomposition pathways in the NTP catalytic system were speculated according to the detected organic matter. This work provides a theoretical and experimental basis for the application of DBD-catalyzed hybrid benzene series VOCs.
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Affiliation(s)
- Yifan Zhu
- School of Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Dandan Li
- School of Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Chunjie Ji
- School of Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Peizhuang Si
- School of Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Xiaolin Liu
- School of Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Yupeng Zhang
- School of Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Fang Liu
- School of Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China
- Key Laboratory of Petroleum and Petrochemical Pollution Control and Treatment, Ministry of Science and Technology, Beijing 102200, China
| | - Lei Hua
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Fenglei Han
- School of Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China
- Key Laboratory of Petroleum and Petrochemical Pollution Control and Treatment, Ministry of Science and Technology, Beijing 102200, China
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3
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Efficient toluene oxidation by post plasma catalysis over hollow Co3O4 nanospheres. RESEARCH ON CHEMICAL INTERMEDIATES 2022. [DOI: 10.1007/s11164-022-04930-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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4
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Sheng Z, Shao L, Zhang L, Zhan P, Wu Z. Catalytic Oxidative Depolymerization of Sodium Lignosulfonate into Valuable Esters over Cu
x
O/m‐Sep Catalyst in H
2
O Solvent Systems. ChemistrySelect 2022. [DOI: 10.1002/slct.202202575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Zhiyuan Sheng
- Ministry of Forestry Bioethanol Research Center College of Materials Science and Engineering Central South University of Forestry and Technology Changsha 410004 China
| | - Lishu Shao
- Ministry of Forestry Bioethanol Research Center College of Materials Science and Engineering Central South University of Forestry and Technology Changsha 410004 China
- Hunan International Joint Laboratory of Woody Biomass Conversion Central South University of Forestry and Technology Changsha 410004 China
- Hunan Engineering Research Center for Woody Biomass Conversion Central South University of Forestry and Technology Changsha 410004 China
| | - Lin Zhang
- Ministry of Forestry Bioethanol Research Center College of Materials Science and Engineering Central South University of Forestry and Technology Changsha 410004 China
- Hunan International Joint Laboratory of Woody Biomass Conversion Central South University of Forestry and Technology Changsha 410004 China
- Hunan Engineering Research Center for Woody Biomass Conversion Central South University of Forestry and Technology Changsha 410004 China
| | - Peng Zhan
- Ministry of Forestry Bioethanol Research Center College of Materials Science and Engineering Central South University of Forestry and Technology Changsha 410004 China
- Hunan International Joint Laboratory of Woody Biomass Conversion Central South University of Forestry and Technology Changsha 410004 China
- Hunan Engineering Research Center for Woody Biomass Conversion Central South University of Forestry and Technology Changsha 410004 China
| | - Zhiping Wu
- Ministry of Forestry Bioethanol Research Center College of Materials Science and Engineering Central South University of Forestry and Technology Changsha 410004 China
- Hunan International Joint Laboratory of Woody Biomass Conversion Central South University of Forestry and Technology Changsha 410004 China
- Hunan Engineering Research Center for Woody Biomass Conversion Central South University of Forestry and Technology Changsha 410004 China
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5
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Analysis of Regional Economy Development on Local Environmental Protection and Natural Resources Utilization from the Perspective of Big Data. JOURNAL OF ENVIRONMENTAL AND PUBLIC HEALTH 2022; 2022:9461377. [PMID: 36213026 PMCID: PMC9536926 DOI: 10.1155/2022/9461377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/07/2022] [Accepted: 09/14/2022] [Indexed: 11/29/2022]
Abstract
The ecological restoration and civilization construction is one of the key tasks in China. The economic development of different regions has different effects on the resource protection and utilization. In the face of complex natural conditions and resource-rich areas, how to carry out the ecological environment promotion work is put forward. The urbanization level of the Yangtze River region increases from 17.9% to 60.6%, showing the characteristics of rapid expansion. In the face of urban diseases such as unreasonable industrial layout, it is urgent to improve regional economy and promote green urban development from the perspective of big data. Adhering to the concept of ecological priority, the development of digital technology drove the development of local economy in 2019, accounting for 43% of the national population. While promoting the economic development, it is of great significance to ensure the efficiency of resource utilization and promote the high-quality development of common economy.
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Zeng Y. Investigation and Countermeasures on Mental Health Status of Applied Fresh Graduates from the Perspective of Psychological Capital. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2022; 2022:5352958. [PMID: 36213581 PMCID: PMC9534641 DOI: 10.1155/2022/5352958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 08/20/2022] [Accepted: 08/27/2022] [Indexed: 12/02/2022]
Abstract
Based on the perspective of psychological capital, the mental health status of applied college graduates is analyzed, and the corresponding countermeasures are put forward. Questionnaires are issued to investigate the mental health status of fresh graduates. The BSSI score of male students (102.05 ± 2.01) is not significantly different from that of female students (P > 0.05). SCL-90 scores of male students include somatization (1.95 ± 0.01), compulsion (1.84 ± 0.15), interpersonal relationship (1.75 ± 0.14), depression (1.92 ± 0.08), anxiety (1.70 ± 0.10), hostility (7.25 ± 0.16), terror (1.35 ± 0.41), bigotry (1.29 ± 0.17), and psychosis (1.33 ± 0.64). There is no significant difference compared with those of female students (P > 0.05). SCL-90 scores of high stress graduates include somatization (2.00 ± 0.17), compulsion (2.30 ± 0.08), interpersonal relationship (1.61 ± 0.20), depression (1.87 ± 0.09), anxiety (1.80 ± 0.11), hostility (1.30 ± 0.20), terror (1.39 ± 0.14), paranoid (1.48 ± 0.10), and psychosis (1.50 ± 0.11). There is significant difference between forced and low pressure graduates (P < 0.05). There is no statistical significance in other items (P > 0.05). Colleges and universities need to work together with fresh graduates to deal with negative emotions and stress, so as to improve mental health and promote employment.
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Affiliation(s)
- Yuanzhen Zeng
- Mental Health Education and Consultation Center, Guangxi Agricultural Vocational and Technical University, Nanning, 530001 Guangxi, China
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Judicial Application of Punitive Damages for Ecological Environment Infringement in Civil Public Interest Litigation. JOURNAL OF ENVIRONMENTAL AND PUBLIC HEALTH 2022; 2022:6127388. [PMID: 36193411 PMCID: PMC9525795 DOI: 10.1155/2022/6127388] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/14/2022] [Accepted: 08/22/2022] [Indexed: 11/17/2022]
Abstract
This study aimed to explore the judicial application of punitive damages for ecological environment infringement in civil public interest litigation. Methods. Combined with a case, the judicial application of punitive damages for ecological environment infringement in civil public interest litigation was analyzed. Results. After thinking and judgment, the total cost of repairing the enterprise plot in the case was 2168000 yuan, the cost of environmental functional loss was 57135.45 yuan, the cost of taking relevant emergency measures such as new drinking water and laundry Wharf Engineering was 532860.11 yuan, and the cost of testing and identification was 95670 yuan. Conclusion. The judicial application should be fully considered in the process of civil public interest litigation to ensure that the punitive compensation for ecological environment infringement is more reasonable.
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8
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Application of Nanofluid Electrochemistry in Heat Dissipation of Permanent Magnet Synchronous Motors. J CHEM-NY 2022. [DOI: 10.1155/2022/3681749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In order to solve the problem of heat dissipation of permanent magnet synchronous motors, a technology using the principle of nanofluid electrochemistry is proposed. The main content of this technology is based on the characteristics and applications of nanofluids; according to the experimental system, the preparation and experimental parameters of nanofluids were determined; finally, by studying the influence of ultrasonic oscillation time and dispersant on the stability of nanofluids, it was concluded that the improvement of the thermal conductivity of nanofluids contributed to the improvement of the heat transfer rate of nanofluids. Experimental results show that when the volume fraction is 0.5, the increase rate of thermal conductivity is 1.51, the increase rate of convective heat transfer coefficient is 20.33, and the increase rate of convective heat transfer coefficient is greater than that of thermal conductivity, which shows that nanofluids have very good heat dissipation ability. It is proved that the technical research of nanofluid can meet the heat dissipation requirements of a permanent magnet synchronous motor.
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Wang X, Wang J, Xie W. Effects of CT Combined with Modified Qinfan Decoction on Improving Sores and Promoting Angiogenesis. CONTRAST MEDIA & MOLECULAR IMAGING 2022; 2022:1649904. [PMID: 36101805 PMCID: PMC9462981 DOI: 10.1155/2022/1649904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 08/09/2022] [Accepted: 08/17/2022] [Indexed: 11/18/2022]
Abstract
In order to explore the clinical treatment of severe acne, this paper proposed the effect of CT technology combined with modified qinfan decoction on improving sores and promoting angiogenesis. From October 2016 to November 2017, 69 patients with severe acne treated in the first traditional Chinese medicine hospital of a city were selected for retrospective analysis. The 69 patients were randomly divided into control group and treatment group. There were 34 patients in the control group and 35 patients in the treatment group. Patients in the control group were treated with VSD. Patients in the treatment group were treated with qinfan decoction combined with VSD. Then, the total effective rate, the time of clinical symptom improvement, the time when the new granulation began to grow, and the time when the sore surface area was reduced by 1/2 were compared between the two groups. The results showed that after treatment, the total effective rate of the treatment group was higher than that of the control group. The time for the improvement of clinical symptoms, the time for the growth of new granulation, and the time for the reduction of the sore surface area by 1/2 were shorter than those of the control group, and the healing rate of the sore surface was higher than that of the control group (P < 0.05). Qinfan decoction combined with negative pressure sealing drainage technology has a significant effect on the treatment of severe acne and can promote its rehabilitation.
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Affiliation(s)
- Xindi Wang
- Liaoning University of Traditional Chinese Medicine, Shenyang, Liaoning 110847, China
| | - Jing Wang
- Geriatric Department, Affiliated Hospital of Liaoning University of Traditional Chinese Medicine, Shengyang, Liaoning 110032, China
| | - Wenbo Xie
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, Jilin 130000, China
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10
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Zheng Z. Load Prediction Model of Athletes' Physical Training Competition Based on Nonlinear Algorithm Combined with Ultrasound. CONTRAST MEDIA & MOLECULAR IMAGING 2022; 2022:3465556. [PMID: 36082063 PMCID: PMC9433221 DOI: 10.1155/2022/3465556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/29/2022] [Accepted: 08/06/2022] [Indexed: 11/24/2022]
Abstract
In order to provide theoretical support and ideas for the "dose" of high-stakes physical activity in athletics, the author has developed models for athletic competition based on nonlinear techniques together with ultrasound. Based on test data, average mean estimation method, and nonlinear regression model estimates, 52 points (46 test points, 6 point estimates) is enrolled in the highest voltage and maximum voltage measurement based on the BP neural network model. The estimation method was developed and the accuracy of the estimation of our estimation method was compared and evaluated using the estimation data. Experimental results show that the average relative error of the average estimate compared to the accuracy of the bench press was 25%, the standard estimate which is not linear regression is 31%, and BP neural network model estimation is 9%. Compared with the accuracy of the assumption of half squatting, the average relative error of the estimated velocity is 13%, the standard nonlinear regression estimate is 20%, and BP neural network model estimated method is 9%. The BP neural network predicts the method with the best performance and intelligence, but its actual functioning and application are complex. The average speed estimate is the most appropriate for use, but the equipment must be high. The process of estimating a linear regression model requires minimal equipment, but its prediction error is high.
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Affiliation(s)
- Zhiliang Zheng
- Ulanqab Inner Mongolia Autonomous Region, Ulanqab Medical College, Wulanchabu City, Inner Mongolia 0474, China
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11
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Lu A, Lu G. Application of MRI and CT Images in Surgical Treatment of Early Cervical Cancer. SCANNING 2022; 2022:1592449. [PMID: 35992041 PMCID: PMC9363930 DOI: 10.1155/2022/1592449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 07/01/2022] [Accepted: 07/12/2022] [Indexed: 06/15/2023]
Abstract
In order to understand the problems of the application of MRI and CT images in the early cervical cancer surgery, a method that the application of MRI imaging and CT images in early cervical cancer surgery was proposed. For the cervical cancer in clinical practice, the applications of the modern imaging examination and the clinical staging classification were investigated and analyzed. Compared with the surgical pathology results, the application value of common modern imaging in clinical staging of cervical cancer was evaluated. It was found that the sensitivity of MRI and CT in diagnosing lymph node metastasis was 56% and 58%, and the specificity was 93% and 92%, respectively. The experiment proved the application value of MRI and CT in clinical staging of cervical cancer.
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Affiliation(s)
- An Lu
- Obstetrics and Gynecology Department, Yixing City People's Hospital, Yixing, Jiangsu 214200, China
| | - Guohua Lu
- Obstetrics and Gynecology Department, Yixing City People's Hospital, Yixing, Jiangsu 214200, China
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12
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Wang YQ, Jiang R, Pan J. Effect of Foot and Hand Massage on Abdominal Pain of Cesarean Section Incision under Ultrasound Guidance. SCANNING 2022; 2022:8356256. [PMID: 35950090 PMCID: PMC9348944 DOI: 10.1155/2022/8356256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/04/2022] [Accepted: 07/14/2022] [Indexed: 06/15/2023]
Abstract
In order to relieve the pain of incision after cesarean section, a method of foot and hand massage for abdominal pain of cesarean section incision under ultrasound guidance was proposed in this paper. In this paper, the experimental control method and retrospective analysis were used to relax the patients through massage, so that the pregnant women could focus on the reaction caused by hand and foot massage, distract their attention, and reduce the pain. The results showed that 60 cases of puerpera after cesarean section were divided into two groups with 30 cases in each group. The control group was only given routine care. The intervention group received 20 min hand and foot massage on the basis of routine care. The visual analog scale (VAS) of pain before, immediately after, 30 min after, and 60 min after massage in the intervention group was evaluated and recorded, and the VAS scores of the control group at the corresponding time points were recorded. The VAS score of the intervention group at each time point after massage was significantly lower than that before massage (P < 0.05), and the VAS score of the intervention group at each time point was significantly lower than that of the control group (P < 0.01). Hand and foot massage can effectively relieve incision pain after cesarean section.
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Affiliation(s)
- Yu Qing Wang
- Pregnant Women School, Changyi People's Hospital, Weifang, Shandong 261300, China
| | - Rongrong Jiang
- Delivery Room, Changyi People's Hospital, Weifang, Shandong 261300, China
| | - Jianmin Pan
- Delivery Room, Changyi People's Hospital, Weifang, Shandong 261300, China
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Zhang J. University Network and New Media Advertising Teaching Design Features and Influence: Environmental Perspective Analysis in Campus Humanistic Governance. JOURNAL OF ENVIRONMENTAL AND PUBLIC HEALTH 2022; 2022:6380719. [PMID: 35910756 PMCID: PMC9334032 DOI: 10.1155/2022/6380719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 06/25/2022] [Accepted: 07/04/2022] [Indexed: 11/30/2022]
Abstract
Under the background of network development in the new era, the integration of multimedia technology and information technology promotes the development of teaching environment. Based on the influence of humanistic governance environment, the university network environment and the advertising teaching environment are constantly integrating new elements with the development of the times, becoming the key point to guarantee the teaching quality. In the research, the relevant data and information were collected and analyzed by the methods of inference and induction analysis. According to the sensory parameters of students' cognitive emotions (n = 64, a > 0.847), the standard deviation was 0.810/0.695 and the action was 0.927/0.655. How to construct the university network and advertising teaching environment were explored. And, in view of the design of the environment characteristics as well as the impact on students, the purpose was to ensure that students had a good learning environment, which could improve the learning efficiency.
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Affiliation(s)
- Jing Zhang
- Department of Literature, Modern College, Northwest University, Xi'an 710130, China
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14
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Guo Q. Preparation and Sound Insulation Performance of Polystyrene Building Flame Retardant and Thermal Insulation Building Materials. Int J Anal Chem 2022; 2022:6444367. [PMID: 35782586 PMCID: PMC9249534 DOI: 10.1155/2022/6444367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 06/11/2022] [Indexed: 11/18/2022] Open
Abstract
In this study, magnesium hydroxide (MH) was modified by sodium dodecylbenzene sulfonate (SDBS) to prepare modified magnesium hydroxide (MMH) flame retardant, which was mixed with polystyrene (PS) to obtain flame retardant PS composite plate. The micromorphology, mechanical properties, thermal stability, and flame retardancy of flame retardant PS composite plate were analyzed. The experimental results show that MMH is well dispersed in PS matrix, PS-MMH-3 has the best tensile strength and elongation at break, the limit oxygen index (LOI) is 44.3% higher than that of pure PS, and the combustion rate is slow, indicating that PS-MMH-3 has good flame retardant properties.
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Affiliation(s)
- Qiulan Guo
- College of Architectural Engineering, Xinyu University, Xinyu, Jiangxi 338004, China
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Bimetallic Copper-Silver Systems Supported on Natural Clinoptilolite: Long-Term Changes in Nanospecies’ Composition and Stability. INORGANICS 2022. [DOI: 10.3390/inorganics10030034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Long-term changes in species of copper-silver bimetallic systems on natural clinoptilolite obtained by ion exchange of Cu2+ and Ag+ and then reduced at different temperatures were studied. Even after storage under ambient conditions, XRD and UV-Vis diffuse reflectance spectra indicate the presence of nanospecies and larger particles of reduced copper and silver. Scanning electron microscopy of aged bimetallic samples, reduced at the highest temperature (450 °C) and the pristine sample for their preparation, also aged, showed the presence of silver particles with a size of about 100 nm. They are formed in the initial ion-exchanged sample (without reduction) due to the degradation of Ag+ ions. The particles in the reduced sample are larger; in both samples they are evenly distributed over the surface. The presence of silver affects the stability and the mechanism of decomposition/oxidation of reduced copper species, and this stability is higher in bimetallic systems. The decomposition pattern of recently reduced species includes the formation of smaller nanoparticles and few-atomic clusters. This can occur, preceding the complete oxidation of Cu to ions. Quasicolloidal silver, which is present in fresh bimetallic samples reduced at lower temperatures, transforms after aging into Ag8 clusters, which indicates the stability of these nanospecies on natural clinoptilolite.
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