Behavior of monolithic prestressed concrete slab track at highway-railway grade crossings

Highway-railway grade crossings are an important part of the transportation system. It allows two types of vehicles to operate in the same areas. Researchers have previously studied the grade crossings, but research on the monolithic prestressed concrete slab (PSCS) track at grade crossings for 1,000mm gauge is limited. At present, there are many types of grade crossing structures that are using in Vietnam. However, these structures still have many disadvantages in the operation process. A new structure type of grade crossing for PSCS is proposed to apply for the 1,000 mm gauge to overcome the main disadvantages of existing structural types. This paper presents test production and experimental measurements to analyze the behavior of PSCS. Test samples of monolithic PSCS were produced in factory. Measurement experiments were conducted in the laboratory. The results of the manufacturing and testing process presented in this paper show that this structure completely meets the criteria of stability and durability under the effect of test loads

Proton Induced X-Ray Emission (PIXE) Analysis on Thick Samples at HUS 5SDH-2 Tandem Accelerator System

The main purpose of this work is to establish a method of elemental analysis by Proton-Induced X-ray Emission (PIXE) technique on thick samples. Our study has been carried out at Hanoi University of Science (HUS) using a 5SDH-2 Tandem accelerator. The X-ray spectra were measured by a Si(Li) detector (FWHM = 139 eV at 5.9 keV) and analyzed off-line using GUPIX software. The validity of the proposed method has been checked through its application to NIST standard samples. The concentrations of the elements have been determined in the standard samples are in agreement with the certified values within the error limits. Our method is now used for the analysis of environmental samples at our laborator

Spatiotemporal evolution of SARS-CoV-2 Alpha and Delta variants during large nationwide outbreak of COVID-19, Vietnam, 2021

We analyzed 1,303 SARS-CoV-2 whole-genome sequences from Vietnam, and found the Alpha and Delta variants were responsible for a large nationwide outbreak of COVID-19 in 2021. The Delta variant was confined to the AY.57 lineage and caused >1.7 million infections and >32,000 deaths. Viral transmission was strongly affected by nonpharmaceutical interventions

Behavior of monolithic prestressed concrete slab track at highway-railway grade crossings

Highway-railway grade crossings are an important part of the transportation system. It allows two types of vehicles to operate in the same areas. Researchers have previously studied the grade crossings, but research on the monolithic prestressed concrete slab (PSCS) track at grade crossings for 1,000mm gauge is limited. At present, there are many types of grade crossing structures that are using in Vietnam. However, these structures still have many disadvantages in the operation process. A new structure type of grade crossing for PSCS is proposed to apply for the 1,000 mm gauge to overcome the main disadvantages of existing structural types. This paper presents test production and experimental measurements to analyze the behavior of PSCS. Test samples of monolithic PSCS were produced in factory. Measurement experiments were conducted in the laboratory. The results of the manufacturing and testing process presented in this paper show that this structure completely meets the criteria of stability and durability under the effect of test loads

The bioeffects resulting from prokaryotic cells and yeast being exposed to an 18 GHz electromagnetic field

The mechanisms by which various biological effects are triggered by exposure to an electromagnetic field are not fully understood and have been the subject of debate. Here, the effects of exposing typical representatives of the major microbial taxa to an 18 GHz microwave electromagnetic field (EMF)were studied. It appeared that the EMF exposure induced cell permeabilisation in all of the bacteria and yeast studied, while the cells remained viable (94% throughout the exposure), independent of the differences in cell membrane fatty acid and phospholipid composition. The resulting cell permeabilisation was confirmed by detection of the uptake of propidium iodine and 23 nm fluorescent silica nanospheres using transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Upon EMF exposure, the bacterial cell membranes are believed to become permeable through quasi-endocytosis processes. The dosimetry analysis revealed that the EMF threshold level required to induce the uptake of the large (46 nm) nanopsheres was between three and six EMF doses, with a specific absorption rate (SAR) of 3 kW/kg and 5 kW/kg per exposure, respectively, depending on the bacterial taxa being studied. It is suggested that the taxonomic affiliation and lipid composition (e.g. the presence of phosphatidyl-glycerol and/or pentadecanoic fatty acid) may affect the extent of uptake of the large nanospheres (46 nm). Multiple 18 GHz EMF exposures over a one-hour period induced periodic anomalous increases in the cell growth behavior of two Staphylococcus aureus strains, namely ATCC 25923 and CIP 65.8T

18 GHz electromagnetic field induces permeability of Gram-positive cocci

The effect of electromagnetic field (EMF) exposures at the microwave (MW) frequency of 18 GHz, on four cocci, Planococcus maritimus KMM 3738, Staphylococcus aureus CIP 65.8T, S. aureus ATCC 25923 and S. epidermidis ATCC 14990T, was investigated. We demonstrate that exposing the bacteria to an EMF induced permeability in the bacterial membranes of all strains studied, as confirmed directly by transmission electron microscopy (TEM), and indirectly via the propidium iodide assay and the uptake of silica nanospheres. The cells remained permeable for at least nine minutes after EMF exposure. It was shown that all strains internalized 23.5 nm nanospheres, whereas the internalization of the 46.3 nm nanospheres differed amongst the bacterial strains (S. epidermidis ATCC 14990T~ 0%; Staphylococcus aureus CIP 65.8T S. aureus ATCC 25923, ~40%; Planococcus maritimus KMM 3738, ~80%). Cell viability experiments indicated that up to 84% of the cells exposed to the EMF remained viable. The morphology of the bacterial cells was not altered, as inferred from the scanning electron micrographs, however traces of leaked cytosolic fluids from the EMF exposed cells could be detected. EMF-induced permeabilization may represent an innovative, alternative cell permeability technique for applications in biomedical engineering, cell drug delivery and gene therapy

Exposure to high-frequency electromagnetic field triggers rapid uptake of large nanosphere clusters by pheochromocytoma cells

Background: Effects of man-made electromagnetic fields (EMF) on living organisms potentially include transient and permanent changes in cell behaviour, physiology and morphology. At present, these EMF-induced effects are poorly defined, yet their understanding may provide important insights into consequences of uncontrolled (e.g., environmental) as well as intentional (e.g., therapeutic or diagnostic) exposure of biota to EMFs. In this work, for the first time, we study mechanisms by which a high frequency (18 GHz) EMF radiation affects the physiology of membrane transport in pheochromocytoma PC 12, a convenient model system for neuro-toxicological and membrane transport studies. Methods and results: Suspensions of the PC 12 cells were subjected to three consecutive cycles of 30s EMF treatment with a specific absorption rate (SAR) of 1.17 kW kg-1, with cells cooled between exposures to reduce bulk dielectric heating. The EMF exposure resulted in a transient increase in membrane permeability for 9 min in up to 90 % of the treated cells, as demonstrated by rapid internalisation of silica nanospheres (diameter d ≈ 23.5 nm) and their clusters (d ≈ 63 nm). In contrast, the PC 12 cells that received an equivalent bulk heat treatment behaved similar to the untreated controls, showing lack to minimal nanosphere uptake of approximately 1-2 %. Morphology and growth of the EMF treated cells were not altered, indicating that the PC 12 cells were able to remain viable after the EMF exposure. The metabolic activity of EMF treated PC 12 cells was similar to that of the heat treated and control samples, with no difference in the total protein concentration and lactate dehydrogenase (LDH) release between these groups. Conclusion: These results provide new insights into the mechanisms of EMF-induced biological activity in mammalian cells, suggesting a possible use of EMFs to facilitate efficient transport of biomolecules, dyes and tracers, and genetic material across cell membrane in drug delivery and gene therapy, where permanent permeabilisation or cell death is undesirable

A technique to achieve estimation of the amount of absorbed energy when using diverse cell types at THz frequencies

The effects of a high frequency electromagnetic field (HF EMF) in the terahertz (THz) range on biological systems is the subject of ongoing investigation. With a beamline range of 0.5 THz - 20 THz, the THz/Far-IR beamline at the Australian Synchrotron is ideally suited to explore possible THz effects. We have developed a technique to achieve precise estimation of the amount of absorbed energy when using diverse cell types at THz frequencies. The approach involves evaluating the overall incident beam power, the determination of the frequency and photon dispersion, and evaluating the relative contribution of the frequency ranges. The sample depth is an important component of the evaluation. Since higher THz frequencies have shallower sample penetration depths, parts of the sample are being exposed to not only different total THz energy doses, but to a different frequency profile. Our technique achieves accurate estimation of the exposure profile

18 GHz electromagnetic field induces permeability of Gram-positive cocci

The effect of electromagnetic field (EMF) exposures at the microwave (MW) frequency of 18 GHz, on four cocci, Planococcus maritimus KMM 3738, Staphylococcus aureus CIP 65.8(T), S. aureus ATCC 25923 and S. epidermidis ATCC 14990(T), was investigated. We demonstrate that exposing the bacteria to an EMF induced permeability in the bacterial membranes of all strains studied, as confirmed directly by transmission electron microscopy (TEM), and indirectly via the propidium iodide assay and the uptake of silica nanospheres. The cells remained permeable for at least nine minutes after EMF exposure. It was shown that all strains internalized 23.5 nm nanospheres, whereas the internalization of the 46.3 nm nanospheres differed amongst the bacterial strains (S. epidermidis ATCC 14990(T)~ 0%; Staphylococcus aureus CIP 65.8(T) S. aureus ATCC 25923, ~40%; Planococcus maritimus KMM 3738, ~80%). Cell viability experiments indicated that up to 84% of the cells exposed to the EMF remained viable. The morphology of the bacterial cells was not altered, as inferred from the scanning electron micrographs, however traces of leaked cytosolic fluids from the EMF exposed cells could be detected. EMF-induced permeabilization may represent an innovative, alternative cell permeability technique for applications in biomedical engineering, cell drug delivery and gene therapy

Translocation and fate of nanospheres in pheochromocytoma cells following exposure to synchrotron-sourced terahertz radiation

The routes by which foreign objects enter cells is well studied; however, their fate following uptake has not been explored extensively. Following exposure to synchrotron-sourced (SS) terahertz (THz) radiation, reversible membrane permeability has been demonstrated in eukaryotic cells by the uptake of nanospheres; nonetheless, cellular localization of the nanospheres remained unclear. This study utilized silica core-shell gold nanospheres (AuSi NS) of diameter 50 ± 5 nm to investigate the fate of nanospheres inside pheochromocytoma (PC 12) cells following SS THz exposure. Fluorescence microscopy was used to confirm nanosphere internalization following 10 min of SS THz exposure in the range 0.5-20 THz. Transmission electron microscopy followed by scanning transmission electron microscopy energy-dispersive spectroscopic (STEM-EDS) analysis was used to confirm the presence of AuSi NS in the cytoplasm or membrane, as single NS or in clusters (22% and 52%, respectively), with the remainder (26%) sequestered in vacuoles. Cellular uptake of NS in response to SS THz radiation could have suitable applications in a vast number of biomedical applications, regenerative medicine, vaccines, cancer therapy, gene and drug delivery