Glassy carbon electrode modified with ex-in-situ gold film – A simple and effective working electrode for As(III) determination by using differential pulse anodic stripping voltammetry

An easy-to-make new working electrode, an ex-in-situ AuF/GCE, was developed for trace As(III) detection. A gold film electrode prepared ex-situ was re-plated in-situ during each arsenic deposition step by adding Au(III) into the analyte solution. The factors affecting arsenic stripping response, namely, gold film preparation conditions, electrolyte concentration, electrode cleaning potential, cleaning time, deposition potential, and deposition time, were investigated. Compared with the traditional gold film electrodes prepared ex-situ, the new electrode has better precision and linearity of arsenic differential pulse anodic stripping voltammetry responses. For a deposition time of 90 s at –200 mV, the new electrode exhibits a sensitivity, a limit of detection (3-Sigma), a limit of quantitation of 0.103 μA·L·μg–1, 0.4 μg·L–1, and 1.3 μg·L–1, respectively

TỔNG HỢP “XANH” GRAPHENE OXIDE DẠNG KHỬ VÀ KHẢO SÁT HOẠT TÍNH ĐIỆN HOÁ

In this work, we synthesized reduced graphene oxide nanosheets by reducing graphene oxide in aqueous solutions with ascorbic acid, which is non-toxic and environmentally friendly. This simple method shows a potential in the bulk production of graphene and graphene-based materials. In addition, the synthesized graphene was utilized to modify a glassy carbon electrode. The resulting electrode can simultaneously detect paracetamol and codeine phosphate with the differential pulse voltammetry method, and it opens up the possible practical application of modified electrodes.Trong nghiên cứu này, chúng tôi tổng hợp các tấm graphene oxide dạng khử thông qua quá trình khử graphene oxide trong nước bằng acid ascorbic không độc hại và thân thiện với môi trường. Phương pháp đơn giản này có tiềm năng trong sản xuất graphene và các vật liệu dựa trên graphene với lượng lớn. Ngoài ra, graphene tổng hợp đã được biến tính lên điện cực than thuỷ tinh, cho phép phân tích đồng thời paracetamol và codeine phosphate bằng phương pháp volt-ampere, sử dụng kỹ thuật xung vi phân, mở ra khả năng ứng dụng trong thực tế của điện cực biến tính

Multimodal Personal Verification Using Likelihood Ratio for the Match Score Fusion

In this paper, the authors present a novel personal verification system based on the likelihood ratio test for fusion of match scores from multiple biometric matchers (face, fingerprint, hand shape, and palm print). In the proposed system, multimodal features are extracted by Zernike Moment (ZM). After matching, the match scores from multiple biometric matchers are fused based on the likelihood ratio test. A finite Gaussian mixture model (GMM) is used for estimating the genuine and impostor densities of match scores for personal verification. Our approach is also compared to some different famous approaches such as the support vector machine and the sum rule with min-max. The experimental results have confirmed that the proposed system can achieve excellent identification performance for its higher level in accuracy than different famous approaches and thus can be utilized for more application related to person verification

Properties of Concrete Containing Rubber Aggregate Derived From Discarded Tires

This study carried out the experiment to evaluate the effects of different contents and sizes of rubber particles derived from discarded tires used for replacing fine and coarse natural aggregates, on the workability of fresh rubberized concrete and the compressive and flexural strengths of hardened rubberized concrete. The study results showed that the workability of fresh rubberized concrete was improved when replacing natural fine aggregate (sand) with fine rubber particles (2.5-5 mm) at the replacing proportions of 30-50% by volume, and when replacing natural coarse aggregate (crushed stone) with coarse rubber particles (5-20 mm) at the replacing proportions of 10-30% by volume. With respect to the mechanical properties of hardened rubberized concrete, a larger reduction in the compressive and flexural strengths was generally found when the replacing proportions increased and when coarse aggregate rather than fine aggregate was replaced by rubber particles at all replacing proportions (10-50%). However, the study results also indicated that using fine rubber particles for replacing fine natural aggregate at the low replacing proportion (up to 10%) might not cause the significant effect on the compressive and flexural strength of rubberized concrete

SỬ DỤNG AXIT OXALIC LÀM CHẤT CHUẨN ĐỂ XÁC ĐỊNH NHU CẦU OXI HÓA HỌC BẰNG PHƯƠNG PHÁP ĐUN HỒI LƯU KÍN – TRẮC QUANG

Potassium hydrogen phthalate (KHP) is used as a standard to determine the chemical oxygen demand (COD) with the closed reflux-colourimetric method (colourimetric method). Besides KHP, it is possible to utilize oxalic acid for this purpose. After boiling at 150 °C for more than 30 minutes in H2SO4 containing Ag2SO4, K2Cr2O7 reacts completely with H2C2O4 at a molar ratio of 1:3. The experimentally determined chemical oxygen demand of H2C2O4 coincides with its theoretical value at 16.0 mg O2/mole H2C2O4. The average COD values of two river water samples, determined with the colourimetric method by using KHP standard and oxalic acid, are not statistically different. Oxalic acid can be used as a standard to determine COD with the colourimetric method.Kali hydro phthalate (KHP) được dùng làm chất chuẩn để xác định nhu cầu oxi hóa học (COD) bằng phương pháp đun hồi lưu kín – trắc quang (phương pháp trắc quang). Ngoài KHP, có thể sử dụng axit oxalic cho mục đích này. Sau khi đun hơn 30 phút ở 150 °C trong môi trường H2SO4 chứa Ag2SO4, K2Cr2O7 sẽ phản ứng hoàn toàn với H2C2O4 theo tỷ lệ mol 1:3. Nhu cầu oxi hóa học của H2C2O4 đã xác định bằng thực nghiệm hoàn toàn trùng khớp với giá trị nhu cầu oxi lý thuyết của hợp chất này là 16,0 mg O2/mol H2C2O4. Nhu cầu oxi hóa học trung bình của hai mẫu nước sông xác định bằng phương pháp trắc quang với hai đường chuẩn dùng KHP và axit oxalic không khác nhau về mặt thống kê. Như vậy, có thể sử dụng axit oxalic làm chất chuẩn để xác định COD bằng phương pháp đã nêu

Datasets of land use change and flood dynamics in the vietnamese mekong delta

This paper compiles the data associated with a research article published in STOTEN [1]. The data set represents figures, tables, and images illustrating the temporal and spatial distribution of land use and flood dynamics from 2000 to 2020 in the Vietnamese Mekong Delta (VMD). The MODIS imageries were freely accessed online via the NASA website [2] and processed to land use and flood maps based on the algorithms by Sakamoto et al. [3,4]. The MODIS products show a high validation with statistical data and radar satellites [1]. The datasets of flood map and land use, therefore, are available to scientists, engineers, and policy-makers in agricultural management associated with flood management in the VMD. They could be used for policy settings, household livelihood assessment as well as other economic analyses for the VMD region due to the change of land use and flooding dynamics

DETERMINATION OF ARSENIC (ILL AND V) BY ANODIC STRIPPING VOLTAMMETRY ON GOLD FILM ELECTRODE

Joint Research on Environmental Science and Technology for the Eart

Outage performance analysis and SWIPT optimization in energy-harvesting wireless sensor network deploying NOMA

Thanks to the benefits of non-orthogonal multiple access (NOMA) in wireless communications, we evaluate a wireless sensor network deploying NOMA (WSN-NOMA), where the destination can receive two data symbols in a whole transmission process with two time slots. In this work, two relaying protocols, so-called time-switching-based relaying WSN-NOMA (TSR WSN-NOMA) and power-splitting-based relaying WSN-NOMA (PSR WSN-NOMA) are deployed to study energy-harvesting (EH). Regarding the system performance analysis, we obtain the closed-form expressions for the exact and approximate outage probability (OP) in both protocols, and the delay-limited throughput is also evaluated. We then compare the two protocols theoretically, and two optimization problems are formulated to reduce the impact of OP and optimize the data rate. Our numerical and simulation results are provided to prove the theoretical and analytical analysis. Thanks to these results, a great performance gain can be achieved for both TSR WSN-NOMA and PSR WSN-NOMA if optimal values of TS and PS ratios are found. In addition, the optimized TSR WSN-NOMA outperforms that of PSR WSN-NOMA in terms of OP.Web of Science193art. no. 61

Label driven Knowledge Distillation for Federated Learning with non-IID Data

In real-world applications, Federated Learning (FL) meets two challenges: (1) scalability, especially when applied to massive IoT networks; and (2) how to be robust against an environment with heterogeneous data. Realizing the first problem, we aim to design a novel FL framework named Full-stack FL (F2L). More specifically, F2L utilizes a hierarchical network architecture, making extending the FL network accessible without reconstructing the whole network system. Moreover, leveraging the advantages of hierarchical network design, we propose a new label-driven knowledge distillation (LKD) technique at the global server to address the second problem. As opposed to current knowledge distillation techniques, LKD is capable of training a student model, which consists of good knowledge from all teachers' models. Therefore, our proposed algorithm can effectively extract the knowledge of the regions' data distribution (i.e., the regional aggregated models) to reduce the divergence between clients' models when operating under the FL system with non-independent identically distributed data. Extensive experiment results reveal that: (i) our F2L method can significantly improve the overall FL efficiency in all global distillations, and (ii) F2L rapidly achieves convergence as global distillation stages occur instead of increasing on each communication cycle.Comment: 28 pages, 5 figures, 10 table

The impact of brand positioning and knowledge on attitude towards brand and purchase intention: A study of organic rice in Ho Chi Minh City

The purpose of this study is to measure the effectiveness of factors of brand, including Brand Positioning, Brand Knowledge, Attitude towards Organic Rice Brand, and Organic Rice Purchase Intention. The survey was conducted with a sample of 224 consumers shopping at four organic rice shops in Ho Chi Minh City. The research was performed by quantitative research methods: Cronbach's Alpha Reliability Analysis, Exploratory Factor Analysis (EFA), Confirm Factor Analysis (CFA), and Structural Equation Modeling (SEM). The research results were conducted in two direct models and the indirect models in which the indirect model was supported. This means that brand positioning and brand knowledge had no direct impact on the Intention to buy organic rice, but only an indirect one through the consumer attitude towards the organic rice brand