Perfluoroalkyl substances in food contact materials: preliminary investigation in Vietnam and global comparison.

Per- and polyfluoroalkyl substances (PFASs) are a group of concerned persistent toxic substances, especially for their application or unintentional formation in food contact materials (FCMs). However, information about the occurrence, sources, and fate of these pollutants in food packaging materials from Vietnam as well as Southeast Asian countries is probably still obscured. In this study, levels of 13 perfluoroalkyl carboxylic acids (PFCAs) and 4 sulfonates (PFSs) were determined in various types of food packaging samples collected from Vietnamese markets.

Highly stable, substrate-free, and flexible broadband halide perovskite paper photodetectors.

In this work, we aim to fabricate a highly stable and flexible perovskite paper photodetector based on a Zn-doped MAFAPbI perovskite and CNC. The paper photodetector has been successfully synthesized by the vacuum filtration method and deposited with interdigitated electrodes. The paper photodetector exhibits a significant photoresponse with a responsivity of 0.

Reconfigurable broadband metasurfaces with nearly perfect absorption and high efficiency polarization conversion in THz range.

Reconfigurable metasurfaces (RMSs) that enable the switching function of absorption and polarization conversion have attracted increasing attention. However, the design of RMSs to achieve wideband and high efficiency for both absorption and polarization conversion functions simultaneously remains a great challenge. Here, we propose the design of a RMS structure with a high-efficiency cross-polarization conversion and nearly perfect absorption.

Perfluoroalkyl substances (PFAS) in freshwater fish from urban lakes in Hanoi, Vietnam: concentrations, tissue distribution, and implication for risk assessment.

Concentrations and profiles of 17 perfluoroalkyl substances (PFAS) including 13 perfluorocarboxylic acids (PFA) and 4 perfluoroalkyl sulfonates (PFS) were determined in whole blood, muscle, and liver samples of four freshwater fish species in West Lake and Yen So Lake (Hanoi, Vietnam). Concentrations of total 17 PFAS in fish blood samples ranged from 5.2 to 29 (median 16) ng/mL.

Simple design of efficient broadband multifunctional polarization converter for X-band applications.

A simple design of a broadband multifunctional polarization converter using an anisotropic metasurface for X-band application is proposed. The proposed polarization converter consists of a periodic array of the two-corner-cut square patch resonators based on the FR-4 substrate that achieves both cross-polarization and linear-to-circular polarization conversions. The simulated results show that the polarization converter displays the linear cross-polarization conversion in the frequency range from 8 to 12 GHz with the polarization conversion efficiency above 90%.

Soil and sediment contamination by unsubstituted and methylated polycyclic aromatic hydrocarbons in an informal e-waste recycling area, northern Vietnam: Occurrence, source apportionment, and risk assessment.

Improper processing activities of e-waste are potential sources of polycylic aromatic hydrocarbons (PAHs) and their derivatives, however, information about the environmental occurrence and adverse impacts of these toxic substances is still limited for informal e-waste recycling areas in Vietnam and Southeast Asia. In this study, unsubstituted and methylated PAHs were determined in surface soil and river sediment samples collected from a rural village with informal e-waste recycling activities in northern Vietnam. Total levels of PAHs and MePAHs decreased in the order: workshop soil (median 2900; range 870-42,000 ng g) > open burning soil (2400; 840-4200 ng g) > paddy field soil (1200; range 530-6700 ng g) > river sediment samples (750; 370-2500 ng g).

Cost-effective capillary electrophoresis with contactless conductivity detection for quality control of beta-lactam antibiotics.

A simple and inexpensive approach for determination of various antimicrobial drugs using a purpose-made compact capillary electrophoresis (CE) instrument with capacitively coupled contactless conductivity detection (CD) is reported. The objective of the work is to propose an affordable and easily-implemented tool for quality control and detection of counterfeiting of antibiotic formulations in resource constrained developing countries. The design of the purpose-made CE-CD system was improved according to the feedback from over 10 years of use of our previous instrument.

Facile design of an ultra-thin broadband metamaterial absorber for C-band applications.

We report a facile design of an ultra-thin broadband metamaterial absorber (MA) for C-band applications by utilizing a single layer of a metal-dielectric-metal structure of FR-4 substrate. The absorption performances are characterized using a numerical method. The proposed MA exhibits the broadband absorption response over the entire C-band spectrum range from 4.

Simple semi-automated portable capillary electrophoresis instrument with contactless conductivity detection for the determination of β-agonists in pharmaceutical and pig-feed samples.

An inexpensive, robust and easy to use portable capillary electrophoresis instrument with miniaturized high-voltage capacitively coupled contactless conductivity detection was developed. The system utilizes pneumatic operation to manipulate the solutions for all flushing steps. The different operations, i.

Graphene-platinum nanohybrid as a robust and low-cost counter electrode for dye-sensitized solar cells.

Dry plasma reduction (DPR) is an excellent approach for easily, continuously, uniformly and stably hybridizing platinum nanoparticles (Pt-NPs) on a graphene-coated layer under atmospheric pressure without any toxic chemicals and at a low temperature. The Pt-NPs with a size of 0.5-4 nm and mostly 2 nm were stably and uniformly hybridized on the surface of reduced graphene oxide (RGO) after co-reduction of Pt precursor ions and GO to Pt atoms and RGO, respectively.

Effects of reduced chemical vapor deposition environment on growth and optical characteristics of TiO2 nanobelts.

TiO2-delta nanobelts were self-catalytically grown at 510 degrees C on bare Si (100) substrates using metallorganic chemical vapor deposition. The nanobelt formation was critically affected by the partial pressure of oxygen. The nanobelts were grown when supplying only Ar or a mixed gas of Ar (90%) and H2 (10%), while thin films were formed with an O2 gas flow of more than 50 cm3 min(-1).