Pub Date : 2023-06-20DOI: 10.25073/2588-1140/vnunst.5559
D. Dang, S. Le, Hai Huy Nguyen
In this study, a series of CuWO4/g-C3N4 composites were synthesized using a facile construction method. The structural characteristics of the composites were examined using various techniques, including XRD, SEM, SEM-EDS, FT-IR, and UV–DRS. The photocatalytic performance of the CuWO4/g-C3N4 nanocomposites was evaluated in the degradation of methylene blue (MB) under visible light irradiation. The findings revealed that the CuWO4/g-C3N4 composite with a mass ratio of 10% CuWO4 displayed the highest efficiency (89%) in degrading MB during an 80-minute photodegradation process, which was consistent with the pseudo-first-order kinetics. These results clearly demonstrate that the formation of a Z-scheme CuWO4/g-C3N4 heterojunction significantly improves the photocatalytic efficiency by promoting rapid separation of electron-hole pairs and enhancing the redox capability. Additionally, the photodegradation efficiency remained above 85% even after four cycles, suggesting the stability of the catalyst.
{"title":"A Novel Heterojunction CuWO4/g-C3N4 Photocatalyst for Removal of Organic Pollutant under Visible Light Irradiation","authors":"D. Dang, S. Le, Hai Huy Nguyen","doi":"10.25073/2588-1140/vnunst.5559","DOIUrl":"https://doi.org/10.25073/2588-1140/vnunst.5559","url":null,"abstract":"In this study, a series of CuWO4/g-C3N4 composites were synthesized using a facile construction method. The structural characteristics of the composites were examined using various techniques, including XRD, SEM, SEM-EDS, FT-IR, and UV–DRS. The photocatalytic performance of the CuWO4/g-C3N4 nanocomposites was evaluated in the degradation of methylene blue (MB) under visible light irradiation. The findings revealed that the CuWO4/g-C3N4 composite with a mass ratio of 10% CuWO4 displayed the highest efficiency (89%) in degrading MB during an 80-minute photodegradation process, which was consistent with the pseudo-first-order kinetics. These results clearly demonstrate that the formation of a Z-scheme CuWO4/g-C3N4 heterojunction significantly improves the photocatalytic efficiency by promoting rapid separation of electron-hole pairs and enhancing the redox capability. Additionally, the photodegradation efficiency remained above 85% even after four cycles, suggesting the stability of the catalyst.","PeriodicalId":23524,"journal":{"name":"VNU Journal of Science: Natural Sciences and Technology","volume":"72 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85992590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-20DOI: 10.25073/2588-1140/vnunst.5565
Nguyen Thi Thai, Nguyen Thi Ha Thu, Do Huy Hoang, Do Van Dang
The study described the preparation of composite material through the dispersion of carbon nanotubes (CNTs) decorated with silver nanoparticles (Ag NPs) in the matrix of blending natural rubber (NR) and polyethylene (PE), for use as an antibacterial agent. The FESEM results indicated the uniform and defect-free surface of the synthesized composites. The mechanical properties of synthesized composite improved with a 65% increase in tensile strength, a 38% increase in elongation, and a 40% increase in hardness compared to the original NR/PE blend materials. Although the addition of CNTs-Ag NPs did not considerably affect the thermal stability of the NR/PE blend, it was found to prevent E. coli bacterial growth by 35%. This opens up new possibilities for the use of the composite in a variety of applications, particularly in the field of public health and wellness.
{"title":"Facile Construction of Silver Decorated on Carbon Nanotube in Natural Rubber and Polyethylene Blend for Antibacterial Activity","authors":"Nguyen Thi Thai, Nguyen Thi Ha Thu, Do Huy Hoang, Do Van Dang","doi":"10.25073/2588-1140/vnunst.5565","DOIUrl":"https://doi.org/10.25073/2588-1140/vnunst.5565","url":null,"abstract":"The study described the preparation of composite material through the dispersion of carbon nanotubes (CNTs) decorated with silver nanoparticles (Ag NPs) in the matrix of blending natural rubber (NR) and polyethylene (PE), for use as an antibacterial agent. The FESEM results indicated the uniform and defect-free surface of the synthesized composites. The mechanical properties of synthesized composite improved with a 65% increase in tensile strength, a 38% increase in elongation, and a 40% increase in hardness compared to the original NR/PE blend materials. Although the addition of CNTs-Ag NPs did not considerably affect the thermal stability of the NR/PE blend, it was found to prevent E. coli bacterial growth by 35%. This opens up new possibilities for the use of the composite in a variety of applications, particularly in the field of public health and wellness.","PeriodicalId":23524,"journal":{"name":"VNU Journal of Science: Natural Sciences and Technology","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76707400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-20DOI: 10.25073/2588-1140/vnunst.5562
Nguyen Son Duong, Duong Xuan Quan, Gundsambuu Narantsatsralt, Vu Van Nhan, Nguyen Pham Ham, Ngo Hong Anh Thu
In this work, a thin-film composite polyamide membrane with antimicrobial polyhexamethylene guanidine (PHMG) was fabricated by the combination of photo-induced and chemical grafting to enhance the antifouling and anti-biofouling properties of the membrane. The surface properties of the membrane were evaluated using field-emission scanning electron microscopy (FE-SEM) images, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), water contact angle (WCA) values, and antimicrobial activity of the membrane. The membrane separation performance was evaluated by the flux and the ability to retain Ca2+ ions in water. The antifouling and anti-biofouling properties were evaluated by the maintained flux ratios after 9 hour-filtration of humic acid and bovine serum albumin (BSA) solutions. The results showed that the grafted membrane’s surface became tighter (the retention increased from 97.3% to 98.6%), and no bacteria were observed on the surface of the grafted membrane. Meanwhile, the anti-fouling and anti-biofouling properties were also improved compared to the original membrane.
{"title":"Enhancing the Antimicrobial and Anti-biofouling Properties of Polyamide Composite Membrane Grafted with Polyhexamethylene Guanidine (PHMG)","authors":"Nguyen Son Duong, Duong Xuan Quan, Gundsambuu Narantsatsralt, Vu Van Nhan, Nguyen Pham Ham, Ngo Hong Anh Thu","doi":"10.25073/2588-1140/vnunst.5562","DOIUrl":"https://doi.org/10.25073/2588-1140/vnunst.5562","url":null,"abstract":"In this work, a thin-film composite polyamide membrane with antimicrobial polyhexamethylene guanidine (PHMG) was fabricated by the combination of photo-induced and chemical grafting to enhance the antifouling and anti-biofouling properties of the membrane. The surface properties of the membrane were evaluated using field-emission scanning electron microscopy (FE-SEM) images, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), water contact angle (WCA) values, and antimicrobial activity of the membrane. The membrane separation performance was evaluated by the flux and the ability to retain Ca2+ ions in water. The antifouling and anti-biofouling properties were evaluated by the maintained flux ratios after 9 hour-filtration of humic acid and bovine serum albumin (BSA) solutions. The results showed that the grafted membrane’s surface became tighter (the retention increased from 97.3% to 98.6%), and no bacteria were observed on the surface of the grafted membrane. Meanwhile, the anti-fouling and anti-biofouling properties were also improved compared to the original membrane.","PeriodicalId":23524,"journal":{"name":"VNU Journal of Science: Natural Sciences and Technology","volume":"118 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88150929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-23DOI: 10.25073/2588-1140/vnunst.5525
Hoang Quoc Anh, Trịnh Hải Minh, Pham Dang Minh, Tu Minh Nhat, Nguyễn Lê Hồng Minh, T. Minh, Shin Takahashi
Polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) are typical brominated flame retardants (BFRs), which were widely added to polymeric and textile materials to meet fire safety requirements. PBDEs (including commercial penta-, octa-, and deca-BDE mixtures) have been classified as persistent organic pollutants (POPs) under the Stockholm Convention, while DBDPE and BTBPE are considered as PBDE replacements. In the present study, concentrations of PBDEs (major congeners of technical PBDE mixtures such as BDE-28, 47, 99, 100, 153, 154, 183, 197, 207, and 209), DBDPE, and BTBPE were simultaneously analyzed in settled dust samples collected from e-waste and end-of-life vehicle (ELV) processing areas in northern Vietnam. The dust samples were extracted by using an ultrasonic processor subsequently by acetone and acetone/hexane (1:1) mixture for 10 min each time. The dust extract was treated with concentrated sulfuric acid and activated silica gel to remove interferences. BFRs were analyzed by using gas chromatography/mass spectrometry (GC/MS) equipped with a DB-5ht column. The mass spectrometer was operated at electron capture negative ionization (ECNI) and selected ion monitoring (SIM) mode. Concentrations of total PBDEs, DBDPE, and BTBPE ranged from 77 to 240,000 (median 6000), from <20 to 240,000 (median 5500), and from <10 to 9200 (median 160) ng/g, respectively. Concentrations of BFRs in the e-waste dust were significantly higher than those measured in the ELV dust, suggesting e-waste processing activities as potential sources of BFRs in dust. Among BFRs analyzed, BDE-209 and DBDPE were the most predominant compounds, implying intensive application of deca-BDE mixtures and alternative formulations.
{"title":"Analysis and Pollution Assessment of Brominated Flame Retardants (PBDEs, DBDPE, and BTPBE) in Settled Dust from E-waste and Vehicle Processing Areas in Northern Vietnam","authors":"Hoang Quoc Anh, Trịnh Hải Minh, Pham Dang Minh, Tu Minh Nhat, Nguyễn Lê Hồng Minh, T. Minh, Shin Takahashi","doi":"10.25073/2588-1140/vnunst.5525","DOIUrl":"https://doi.org/10.25073/2588-1140/vnunst.5525","url":null,"abstract":"Polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) are typical brominated flame retardants (BFRs), which were widely added to polymeric and textile materials to meet fire safety requirements. PBDEs (including commercial penta-, octa-, and deca-BDE mixtures) have been classified as persistent organic pollutants (POPs) under the Stockholm Convention, while DBDPE and BTBPE are considered as PBDE replacements. In the present study, concentrations of PBDEs (major congeners of technical PBDE mixtures such as BDE-28, 47, 99, 100, 153, 154, 183, 197, 207, and 209), DBDPE, and BTBPE were simultaneously analyzed in settled dust samples collected from e-waste and end-of-life vehicle (ELV) processing areas in northern Vietnam. The dust samples were extracted by using an ultrasonic processor subsequently by acetone and acetone/hexane (1:1) mixture for 10 min each time. The dust extract was treated with concentrated sulfuric acid and activated silica gel to remove interferences. BFRs were analyzed by using gas chromatography/mass spectrometry (GC/MS) equipped with a DB-5ht column. The mass spectrometer was operated at electron capture negative ionization (ECNI) and selected ion monitoring (SIM) mode. Concentrations of total PBDEs, DBDPE, and BTBPE ranged from 77 to 240,000 (median 6000), from <20 to 240,000 (median 5500), and from <10 to 9200 (median 160) ng/g, respectively. Concentrations of BFRs in the e-waste dust were significantly higher than those measured in the ELV dust, suggesting e-waste processing activities as potential sources of BFRs in dust. Among BFRs analyzed, BDE-209 and DBDPE were the most predominant compounds, implying intensive application of deca-BDE mixtures and alternative formulations.","PeriodicalId":23524,"journal":{"name":"VNU Journal of Science: Natural Sciences and Technology","volume":"72 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90956397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-15DOI: 10.25073/2588-1140/vnunst.5515
Tran Nam Anh, D. Duong, N. Huấn, Nguyen Thi Hanh, Nguyen Thi Hien, D. Linh, N. M. Hoang, Hoang Thu Trang
In this study, phenol was adsorbed by commercial coconut shell charcoal (CSC), which is inexpensive, commercially available, non-toxic, and environmentally friendly. The measurements, namely the density functional theory (DFT) calculation, the energy-dispersive X-ray spectroscopy (EDS), and the Fourier-transform infrared spectroscopy (FTIR), were conducted to characterize the features of the CSC. The highest phenol removal efficiency reached 78.62% at optimal conditions (pH: 7, initial concentration of phenol: 20 mg/L, adsorption time: 120 minutes, and dosage of CSC: 2.5 g/L). The phenol adsorption process follows the Langmuir adsorption model with the coefficient R2 = 0.9964. The maximum adsorption capacity by the CSC was determined to be 14.32 mg/g. The process of desorption of phenol from CSC was most effective in the NaOH solution. On the other hand, the adsorption efficiency of CSC gradually decreased after five consecutive cycles. At the fifth use, the phenol uptake efficiency reached 22.2%.
{"title":"Removal of Phenol from Water by Commercial Coconut Shell Charcoal","authors":"Tran Nam Anh, D. Duong, N. Huấn, Nguyen Thi Hanh, Nguyen Thi Hien, D. Linh, N. M. Hoang, Hoang Thu Trang","doi":"10.25073/2588-1140/vnunst.5515","DOIUrl":"https://doi.org/10.25073/2588-1140/vnunst.5515","url":null,"abstract":"In this study, phenol was adsorbed by commercial coconut shell charcoal (CSC), which is inexpensive, commercially available, non-toxic, and environmentally friendly. The measurements, namely the density functional theory (DFT) calculation, the energy-dispersive X-ray spectroscopy (EDS), and the Fourier-transform infrared spectroscopy (FTIR), were conducted to characterize the features of the CSC. The highest phenol removal efficiency reached 78.62% at optimal conditions (pH: 7, initial concentration of phenol: 20 mg/L, adsorption time: 120 minutes, and dosage of CSC: 2.5 g/L). The phenol adsorption process follows the Langmuir adsorption model with the coefficient R2 = 0.9964. The maximum adsorption capacity by the CSC was determined to be 14.32 mg/g. The process of desorption of phenol from CSC was most effective in the NaOH solution. On the other hand, the adsorption efficiency of CSC gradually decreased after five consecutive cycles. At the fifth use, the phenol uptake efficiency reached 22.2%.","PeriodicalId":23524,"journal":{"name":"VNU Journal of Science: Natural Sciences and Technology","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78916626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-15DOI: 10.25073/2588-1140/vnunst.5496
N. V. Dũng, Nguyen Thi Xuan Thi, Le Vinh Truong
This study evaluated the feasibility of using methyl ester prepared from waste cooking oil for electrical insulation in distribution transformers. Methyl ester is produced by a transesterification reaction between waste cooking oil and methanol using sodium hydroxide as a catalyst. The physicochemical parameters and breakdown voltage of the methyl ester were determined. The effects of ageing on breakdown voltage, viscosity and acid value of methyl ester were also investigated. In addition, the breakdown voltage of Kraft paper impregnated with methyl ester was determined. Experimental results showed that methyl ester from waste cooking oil had low viscosity (5.17 cSt) and high breakdown voltage (40.3 kV). Other parameters also meet ASTM D6871 except for the pour and flash points. Ageing insignificantly affected the breakdown voltage of the methyl ester. After ageing, the breakdown voltage of the methyl ester increased to 42.1 kV. However, the viscosity of the methyl ester also increased by 23.5% and the acid value increased by 79.2 times. Finally, the breakdown voltage of Kraft paper impregnated with the methyl ester was about 5-10% lower than that of paper impregnated with the mineral oil.
{"title":"Synthesis of Methyl Ester from Waste Cooking Oil Toward Application in Transformer’s Insulating Liquid","authors":"N. V. Dũng, Nguyen Thi Xuan Thi, Le Vinh Truong","doi":"10.25073/2588-1140/vnunst.5496","DOIUrl":"https://doi.org/10.25073/2588-1140/vnunst.5496","url":null,"abstract":"This study evaluated the feasibility of using methyl ester prepared from waste cooking oil for electrical insulation in distribution transformers. Methyl ester is produced by a transesterification reaction between waste cooking oil and methanol using sodium hydroxide as a catalyst. The physicochemical parameters and breakdown voltage of the methyl ester were determined. The effects of ageing on breakdown voltage, viscosity and acid value of methyl ester were also investigated. In addition, the breakdown voltage of Kraft paper impregnated with methyl ester was determined. Experimental results showed that methyl ester from waste cooking oil had low viscosity (5.17 cSt) and high breakdown voltage (40.3 kV). Other parameters also meet ASTM D6871 except for the pour and flash points. Ageing insignificantly affected the breakdown voltage of the methyl ester. After ageing, the breakdown voltage of the methyl ester increased to 42.1 kV. However, the viscosity of the methyl ester also increased by 23.5% and the acid value increased by 79.2 times. Finally, the breakdown voltage of Kraft paper impregnated with the methyl ester was about 5-10% lower than that of paper impregnated with the mineral oil. ","PeriodicalId":23524,"journal":{"name":"VNU Journal of Science: Natural Sciences and Technology","volume":"13 4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72689227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-12DOI: 10.25073/2588-1140/vnunst.5185
N. Liêm, N. P. Linh, N. H. Tùng, Bach Trong Phuc
This study has investigated the effect of hydroperoxide treatment on the properties of bagasse fibers in order to get the value added material using by-products from sugar production such as reinforcement for composite materials. The results of processing bagasse fibers with hydroperoxide at different concentration, temperature and treatement time showed that treatment condition had a great influence on the properties of the obtained fibers. With the suitable treatement conditions of 10% peroxide concentration, treatment time of 40 minutes, treatment temperature at 60 0C, the treated fiber has a more homogeneous surface than the untreated. The composite using hybrid bagasse/glass fiber has higher flexural and impact resistance than when using glass fiber and reaches 162.6 MPa and 38.9 KJ/m2 (16.7% and 213% respectively compared to composite using glass fiber only). This can be explained that the treated bagasse fiber has better wetting ability with the matrix resin and together with the energy absorption capacity of the fiber bundle, it leads to an increase in flexural strength and impact strength of composite material.
{"title":"Investigating the Influence of Hydroperoxide Treatment on the Bagasse Fiber Reinforced Composite Properties","authors":"N. Liêm, N. P. Linh, N. H. Tùng, Bach Trong Phuc","doi":"10.25073/2588-1140/vnunst.5185","DOIUrl":"https://doi.org/10.25073/2588-1140/vnunst.5185","url":null,"abstract":"This study has investigated the effect of hydroperoxide treatment on the properties of bagasse fibers in order to get the value added material using by-products from sugar production such as reinforcement for composite materials. The results of processing bagasse fibers with hydroperoxide at different concentration, temperature and treatement time showed that treatment condition had a great influence on the properties of the obtained fibers. With the suitable treatement conditions of 10% peroxide concentration, treatment time of 40 minutes, treatment temperature at 60 0C, the treated fiber has a more homogeneous surface than the untreated. The composite using hybrid bagasse/glass fiber has higher flexural and impact resistance than when using glass fiber and reaches 162.6 MPa and 38.9 KJ/m2 (16.7% and 213% respectively compared to composite using glass fiber only). This can be explained that the treated bagasse fiber has better wetting ability with the matrix resin and together with the energy absorption capacity of the fiber bundle, it leads to an increase in flexural strength and impact strength of composite material.","PeriodicalId":23524,"journal":{"name":"VNU Journal of Science: Natural Sciences and Technology","volume":"406 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77710019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-12DOI: 10.25073/2588-1140/vnunst.5505
Nguyen Thi Ngoc Anh, N. D. Trung, N. X. Dang
The population of the Tonkin Snub-nosed Monkey (Rhinopithecus avunculus) in Cao - Ta - Tung forest of Quan Ba district, Ha Giang province is approximately from 10 to 20 individuals. Because the distribution of this population is located outside of a special-use forest, the habitat of the species is fragmented and continuing to decline due to agricultural expansion and human disturbance. The research results showed that the main livelihood of local people is growing corn and cardamom. There are still activities of forest product exploitation, mainly for firewood. Five major threats to the population of Rhinopithecus avunculus in Cao - Ta - Tung forest are hunting activities, timber logging, non-timber forest product exploitation, deforestation for farming, and cardamom cultivation. The activities of local people in Va Thang 2, Ta Van and Chong Chai villages have a very high level of threat, while Cha Phin and Ban Thang villages have a high level of threat. The expansion of the planting area of cardamom (Amomum tsao) under the forest canopy by local people has made the forest area shrink, which has seriously affected the habitat of the population. In order to protect the habitat and population of the Tonkin Snub-nosed Monkey in Quan Ba district, the following conservation measure should be considered: i) Establish the Quan Ba Tonkin Snub-nosed Monkey Species and Habitat Conservation Area; ii) Take measures to prevent the expansion of cardamom cultivation under the forest canopy; iii) Enhance communication to raise public awareness on this species protection, forest protection as well as biodiversity conservation; and iv) Develop livelihood models for local communities to improve living standards and reduce pressure on forests.
{"title":"An Assessment of Impacts of Local Communities on the Habitat of the Tonkin Snub-nosed Monkey (Rhinopithecus avunculus) Population in Quan Ba District, Ha Giang Province","authors":"Nguyen Thi Ngoc Anh, N. D. Trung, N. X. Dang","doi":"10.25073/2588-1140/vnunst.5505","DOIUrl":"https://doi.org/10.25073/2588-1140/vnunst.5505","url":null,"abstract":"The population of the Tonkin Snub-nosed Monkey (Rhinopithecus avunculus) in Cao - Ta - Tung forest of Quan Ba district, Ha Giang province is approximately from 10 to 20 individuals. Because the distribution of this population is located outside of a special-use forest, the habitat of the species is fragmented and continuing to decline due to agricultural expansion and human disturbance. The research results showed that the main livelihood of local people is growing corn and cardamom. There are still activities of forest product exploitation, mainly for firewood. Five major threats to the population of Rhinopithecus avunculus in Cao - Ta - Tung forest are hunting activities, timber logging, non-timber forest product exploitation, deforestation for farming, and cardamom cultivation. The activities of local people in Va Thang 2, Ta Van and Chong Chai villages have a very high level of threat, while Cha Phin and Ban Thang villages have a high level of threat. The expansion of the planting area of cardamom (Amomum tsao) under the forest canopy by local people has made the forest area shrink, which has seriously affected the habitat of the population. In order to protect the habitat and population of the Tonkin Snub-nosed Monkey in Quan Ba district, the following conservation measure should be considered: i) Establish the Quan Ba Tonkin Snub-nosed Monkey Species and Habitat Conservation Area; ii) Take measures to prevent the expansion of cardamom cultivation under the forest canopy; iii) Enhance communication to raise public awareness on this species protection, forest protection as well as biodiversity conservation; and iv) Develop livelihood models for local communities to improve living standards and reduce pressure on forests.","PeriodicalId":23524,"journal":{"name":"VNU Journal of Science: Natural Sciences and Technology","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84866406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-12DOI: 10.25073/2588-1140/vnunst.5546
Duong Xuan Quan, Nguyễn Hoàng Ngọc Phương, Lai Mai Huong, Nguyen Pham Ham, T. T. Dung, Ngo Hong Anh Thu
To enhance the antifouling resistance, this study modified commercial thin-film composite polyamide membranes with chitosan by redox-initiated graft polymerization process before treating the modified membrane’s surface using sodium hypochlorite. The surfaces of the modified membranes were characterized using field emission scanning electron microscopy, and attenuated total reflection - Fourier transform infrared spectroscopy. The membranes’ performance and fouling resistance were shown through flux, retention, and maintained flux ratios during the filtration of calcium chloride solution. In addition, the antibacterial ability of membranes was evaluated through the growth of bacteria on their surface, and the anti-biofouling resistance of these membranes was evaluated through the maintained flux ratios, irreversible antifouling factor, and flux after 90-minute filtration of actual river water. The results showed that the modified membrane had superior antibacterial ability compared to the original membrane. Additionally, although the flux was reduced slightly, the modified membrane treated with NaClO exhibited a remarkable improvement in the maintained flux ratios (up to 99%) and the irreversible antifouling factor (~ 100%). This is similar to the filtration of actual river water, the chitosan-grafted polyamide membrane after NaClO treatment was shown to be more effective than the unmodified membrane in reducing the fouling phenomenon.
{"title":"Treatment of Chitosan Modified-composite Polyamide Membranes by Sodium Hypochlorite for Enhancing Antifouling Property","authors":"Duong Xuan Quan, Nguyễn Hoàng Ngọc Phương, Lai Mai Huong, Nguyen Pham Ham, T. T. Dung, Ngo Hong Anh Thu","doi":"10.25073/2588-1140/vnunst.5546","DOIUrl":"https://doi.org/10.25073/2588-1140/vnunst.5546","url":null,"abstract":"To enhance the antifouling resistance, this study modified commercial thin-film composite polyamide membranes with chitosan by redox-initiated graft polymerization process before treating the modified membrane’s surface using sodium hypochlorite. The surfaces of the modified membranes were characterized using field emission scanning electron microscopy, and attenuated total reflection - Fourier transform infrared spectroscopy. The membranes’ performance and fouling resistance were shown through flux, retention, and maintained flux ratios during the filtration of calcium chloride solution. In addition, the antibacterial ability of membranes was evaluated through the growth of bacteria on their surface, and the anti-biofouling resistance of these membranes was evaluated through the maintained flux ratios, irreversible antifouling factor, and flux after 90-minute filtration of actual river water. The results showed that the modified membrane had superior antibacterial ability compared to the original membrane. Additionally, although the flux was reduced slightly, the modified membrane treated with NaClO exhibited a remarkable improvement in the maintained flux ratios (up to 99%) and the irreversible antifouling factor (~ 100%). This is similar to the filtration of actual river water, the chitosan-grafted polyamide membrane after NaClO treatment was shown to be more effective than the unmodified membrane in reducing the fouling phenomenon.","PeriodicalId":23524,"journal":{"name":"VNU Journal of Science: Natural Sciences and Technology","volume":"70 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81623059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-12DOI: 10.25073/2588-1140/vnunst.5535
Kieu Van Anh, Dao Yen Nhi, Vu Tung Lam, Le Duc Quan, Tran Thi Nhu Hao, Hoang Quoc Anh, Nguyen Thi Kim Thuong, Le Duc Dung, Pham Thi Mai, Nguyen Thi Huong
Combination drugs including antibiotics are frequently used for additional therapeutic effects. This fact raises the need for effective methods to simultaneously determine antibiotics of different classes. In this study, four antibiotics including vancomycin, cefoperazone, sulbactam, and ceftriaxone were determined simultaneously by capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D). The analytical conditions including effective length of silica capillary, background electrolyte solutions, separation voltages, and injection modes are investigated. The selected analytical conditions were: silica capillary (internal diameter 50 μm, total length 60 cm, effective length 30 cm); background electrolyte solution 10 Mm L-arginine/acetic acid (pH 9.2); separation voltage +17 kV; siphoning hydrodynamic sample injection at 10 cm height for 20 s. Limits of detection (LOD) of vancomycin, cefoperazone, sulbactam, and ceftriaxone were 2.0 ppm, 1.5 ppm, 1.0 ppm, and 2.0 ppm, respectively. Good linearity (R2 > 0.999) was achieved for all the target compounds until concentrations as high as 100 ppm. Analytical results of blank-spike samples indicate acceptable recovery (97.5% - 100.4%) and repeatability (RSD: 0.99% - 3.04%). The validated method has been applied to determine these four antibiotics in several pharmaceutical samples. Good agreement between results of our method and the LC-MS/MS method, suggesting CE-C4D is a reliable and cost-effective method in pharmaceutical analysis.
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