Room temperature ammonia gas sensor based on p-type-like V2O5 nanosheets towards food spoilage monitoring

Gas sensors play an important role in many areas of human life, including the monitoring of production processes, occupational safety, food quality assessment, and air pollution monitoring. Therefore, the need for gas sensors to monitor hazardous gases, such as ammonia, at low operating temperatures has become increasingly important in many fields. Sensitivity, selectivity, low cost, Citation: Van Duy, L.; Nguyet, T.T.; Le, D.T.T.; Van Duy, N.; Nguyen, H.; Biasioli, F.; Tonezzer, M.; Di Natale, C.; Hoa, N.D. Room Temperature AmmoniaGasSensor Based on p-Type-like V2O5 Nanosheets towards Food Spoilage Monitoring. Nanomaterials 2023, 13, 146. https:// doi.org/10.3390/nano13010146 Academic Editors: Sergei Kulinich and Li Hai Received: 17 November 2022 Revised: 23 December 2022 Accepted: 24 December 2022 Published: 28 December 2022 Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). and ease of production are crucial characteristics for creating a capillary network of sensors for the protection of the environment and human health. However, developing gas sensors that are not only efficient but also small and inexpensive and therefore integrable into everyday life is a difficult challenge. In this paper, we report on a resistive sensor for ammonia detection based on thin V2O5 nanosheets operating at room temperature. The small thickness and porosity of the V2O5 nanosheets give the sensors good performance for sensing ammonia at room temperature (RT), with a relative change of resistance of 9.4% to 5 ppm ammonia (NH3) and an estimated detection limit of 0.4 ppm. The sensor is selective with respect to the seven interferents tested; it is repeatable and stable over the long term (four months). Although V2O5 is generally an n-type semiconductor, in this case the nanosheets show a p-type semiconductor behavior, and thus a possible sensing mechanism is proposed. The device’s performance, along with its size, low cost, and low power consumption, makes it a good candidate for monitoring freshness and spoilage along the food supply chai

Teachers’ feelings of safeness in school-family-community partnerships: Motivations for sustainable development in moral education

This study aims to get insights into teachers' safety feelings in families, schools, and communities’ partnerships to facilitate the Vietnam context’s moral education process. We used a survey method with the instrument having 19 Likert-scale items, namely teachers' feelings of safeness in SFC partnerships (SSFC). The data from 371 Vietnamese teachers followed a simple random sampling strategy. We conduct multiple regression analyses to get insight into the relationship between four groups of variables and teachers' feelings of safeness, namely teachers’ background, collaborated actions between teachers and families, families’ mental encouragement for teachers, and collaborated actions between families and communities. These results find that the school level, collaborated actions between teachers and families, and families’ mental encouragement for teachers are statistically significant to teachers’ feelings of safety. Moreover, the variable group of collaborated actions between teachers and families records the highest positive beta value in multiple regression analyses. In other words, the improvement of collaborated actions between teachers and families is a critical motivation to leverage teachers’ feelings of safeness in SFC partnerships. These results provide valuable information for sustainable development in moral education

DESIGN AND ANALYSIS OF COMPACT METAMATERIAL MIMO ANTENNA FOR WLAN APPLICATIONS

A compact three-port metamaterial multiple-input-multiple-output (MIMO) antenna using complementary split-ring resonator (CSRR) loaded ground have demonstrated in order to miniaturize the size and improve the antenna performance. The antenna is designed on FR4 material and simulated by HFSS software. By loading CSRRs in the ground plane, the size reduction of 77% of the individual patch antenna element is achieved, which appeared to be the major reason for the obtained the compact MIMO antenna. Furthermore, the simulated results show that the proposed MIMO antenna achieves the total gain higher than 5 dB, the isolation less than -11 dB, the envelope correlation coefficient (ECC) value lower than 0.015, and the bandwidth of 100 MHz through the whole WLAN band from 2.4 GHz to 2.484 GHz, indicating promises for WLAN applications

ARE CONSUMERS WILLING TO PAY MORE FOR TRACEABILITY? EVIDENCE FROM AN AUCTION EXPERIMENT OF VIETNAMESE PORK

This study aims to conduct the consumer’s willingness to pay (WTP) for traceable pork products by using the auction experiments methods, estimate the factors affecting to the WTP and identify the demand for specific information in traceability systems from information of consumers in Vietnam. The results indicated that, the WTP for traceable pork products of consumers is higher than 24%, comparing to the non-traceable pork products. The frequency of pork consumption, gender, age, education, health self-report and consumer’s attitude from risk of unsafe pork products were the influencing factors to the consumer’s WTP for traceable pork. The necessary information of traceability, suggested by consumers, included: information of additives included in the purchased pork, place of origin, expiration date and quality certificate

H2_{2}O2_{2} production in Lactobacillus strains isolated from the intestinal microbiome of healthy people

Lactobacillus sp. in the digestive tract are capable of producing H2O2 to inhibit the growth of harmful bacteria and balance the gut microflora. In this study, we have isolated 115 strains of Lactobacillus spp. from stool samples of healthy people in Ha Noi. Of the 50 tested Lactobacillus strains, 9 strains were capable of producing H2O2, of which the Lac.VFE-14 strain produced highly H2O2 with a concentration of 2.183 mM, followed by Lac.VFE-08 strains (2.081 mM) and Lac.VFE-04 (2.067 mM). All three strains grew well in MRS medium supplemented with bile salts or adjusted to low pH value. With 0.3% of bile salt, the survival rates of these 3 strains were 99%, 95% and 97%, respectively. At pH 3.0, after 3 hours of cultivation, the survival rates of the three strains were 98.54%, 94.15% and 95.27%, respectively. In addition, each of the cell-free culture supernatants of these three strains that inhibit the growth of S. aureus ATCC-23235. The inhibition zone diameters of the three strains were 19.0±1.0 mm, 14.0±1.0 mm and 11.7±1.3 mm, respectively. The results of 16S rRNA gene analyses showed that Lac.VFE-14, Lac.VFE-08 and Lac.VFE-04 had high similarity scores with L. plantarum ZZU 23 (100%), L. rhamnosus JCM 1136 (99%) and L. plantarum S7 (98.65%), respectively. This study indicates that all three strains have the potential to be used as probiotics in the future.