The effect of MnCO3 on the gain coefficient for the 4I13/2 → 4I15/2 transition of Er3+ ions and near-infrared emission bandwidth flatness of Er3+/Tm3+/Yb3+ co-doped barium zinc silicate glasses.

The roles of Mn2+ ions in the MnCO3 compound, leading to the formation of an Mn2+-Yb3+ dimer and affecting the gain coefficient for the 4I13/2 → 4I15/2 transition of Er3+ ions and near-infrared (NIR) emission bandwidth flatness of Er3+/Tm3+/Yb3+ co-doped in SiO2-ZnO-BaO (SZB) barium zinc silicate glasses, were investigated in this work. The composition of all elements from the original raw materials that exist in the host glasses was determined using energy-dispersive X-ray spectroscopy (EDS). Under the excitation of a 980 nm laser diode (LD), the NIR emission of Er3+/Tm3+/Yb3+-co-doped SZB glasses produced a bandwidth of about 430 nm covering the O, E, and C bands. The effects of Mn2+ ions and the Mn2+-Yb3+ dimer on the gain coefficient for the 4I13/2 → 4I15/2 transition of Er3+ ions and bandwidth flatness of NIR emission of Er3+/Tm3+-co-doped and Er3+/Tm3+/Yb3+-co-doped SZB glasses were also assigned. The optimal molar concentration of Mn2+ ions was determined such that the NIR bandwidth flatness of Er3+/Tm3+/Yb3+-co-doped SZB glasses was the flattest. In addition, the role of Mn2+ ions in reducing the gain coefficient for the 4I13/2 → 4I15/2 transition of Er3+ ions was also calculated and discussed.

Optical band gaps and spectroscopy properties of Bi m+/Eu n+/Yb3+ co-doped (m = 0, 2, 3; and n = 2, 3) zinc calcium silicate glasses.

In this study, the indirect/direct optical band gaps and spectroscopy properties of Bi m+/Eu n+/Yb3+ co-doped (m = 0, 2, 3; and n = 2, 3) zinc calcium silicate glasses under different excitation wavelengths were investigated. Zinc calcium silicate glasses with the main compositions of SiO2-ZnO-CaF2-LaF3-TiO2 were prepared by the conventional melting method. EDS analysis was performed to determine the elemental composition existing in the zinc calcium silicate glasses. Visible (VIS)-, upconversion (UC)-, and near-infrared (NIR)-emission spectra of Bi m+/Eu n+/Yb3+ co-doped glasses were also investigated. Indirect optical band gaps and direct optical band gaps of Bi m+-, Eu n+- single-doped, and Bi m+-Eu n+ co-doped SiO2-ZnO-CaF2-LaF3-TiO2-Bi2O3-EuF3-YbF3 zinc calcium silicate glasses were calculated and analyzed. CIE 1931(x, y) color coordinates for VIS and UC emission spectra of Bi m+/Eu n+/Yb3+ co-doped glasses were determined. Besides, the mechanism of VIS-, UC-, NIR-emissions, and energy transfer (ET) processes between Bi m+ and Eu n+ ions were also proposed and discussed.

Conductive Gels: Properties and Applications of Nanoelectronics.

Conductive gels are a special class of soft materials. They harness the 3D micro/nanostructures of gels with the electrical and optical properties of semiconductors, producing excellent novel attributes, like the formation of an intricate network of conducting micro/nanostructures that facilitates the easy movement of charge carriers. Conductive gels encompass interesting properties, like adhesion, porosity, swelling, and good mechanical properties compared to those of bulk conducting polymers. The porous structure of the gels allows the easy diffusion of ions and molecules and the swelling nature provides an effective interface between molecular chains and solution phases, whereas good mechanical properties enable their practical applications. Due to these excellent assets, conductive gels are promising candidates for applications like energy conversion and storage, sensors, medical and biodevices, actuators, superhydrophobic coatings, etc. Conductive gels offer promising applications, e.g., as soft sensors, energy storage, and wearable electronics. Hydrogels with ionic species have some potential in this area. However, they suffer from dehydration due to evaporation when exposed to the air which limits their applications and lifespan. In addition to conductive polymers and organic charge transfer complexes, there is another class of organic matter called "conductive gels" that are used in the organic nanoelectronics industry. The main features of this family of organic materials include controllable photoluminescence, use in photon upconversion technology, and storage of optical energy and its conversion into electricity. Various parameters change the electronic and optical behaviors of these materials, which can be changed by controlling some of the structural and chemical parameters of conductive gels, their electronic and optical behaviors depending on the applications. If the conjugated molecules with π bonds come together spontaneously, in a relative order, to form non-covalent bonds, they form a gel-like structure that has photoluminescence properties. The reason for this is the possibility of excitation of highest occupied molecular orbital level electrons of these molecules due to the collision of landing photons and their transfer to the lowest unoccupied molecular orbital level. This property can be used in various nanoelectronic applications such as field-effect organic transistors, organic solar cells, and sensors to detect explosives. In this paper, the general introduction of conductive or conjugated gels with π bonds is discussed and some of the physical issues surrounding electron excitation due to incident radiation and the mobility of charge carriers, the position, and role of conductive gels in each of these applications are discussed.

Lead Environmental Pollution and Childhood Lead Poisoning at Ban Thi Commune, Bac Kan Province, Vietnam.

Lead poisoning is a public health problem in many areas of the world. Children are at particularly high risk for adverse effects of lead exposure; even at low concentrations, lead can affect physical, mental, and behavioral development. Children living near lead-zinc mines are at high risk for environmental lead poisoning, especially the contaminated soil. We conducted a cross-sectional descriptive study in Ban Thi Commune, northern Vietnam. 195 children (92,9% participation) aged 3-14 years old (average: 7.69 ± 2.90) were randomly selected from a list of all children prepared by the village health collaborators. 109 (55.90%) were boys and 86 (44.10%) were girls. The research measures were the lead concentration in native soil and the children's total blood lead concentration determined by the inductively coupled plasma-mass spectrometry (ICP-MS) method. The results showed that lead content in soil was many times higher than American Environmental Protection Agency and Vietnam standards (average 2980.23 ± 6092.84 mg/kg dry weight of soil (range 80.05 - 33820.62)). Average blood lead levels for children were 15.42 ± 6.45 µg/dL (95% CI: 14.50 -16.33 µg/dL). The percentage of children with lead levels >10 µg/dL (value considered to be lead poisoning for children according to the Ministry of Health of Vietnam) was 79.49% of the total number of children. None of the children in this study had blood lead level (BLL) that required chelation treatment according to Vietnam MOH guideline (BLL ≥45 µg/dL). There is weakly evidence that lead exposure relates to the physical development of children. Children with low lead concentrations (less than 10 µg/dL) had height and weight of 1.47-3.51 cm and 1.19-2.81 kg, greater than those with BLL >10 µg/dL (p>0.05).