This study explored how first-year students perceived their learning experience at Industrial University of Ho Chi Minh city (IUH). The freshmen’s learning experience was measured by their academic, social, and emotional involvement in educationally purposeful activities. The research also examined the intercorrelations of various aspects of learning experience and their relationships with freshmen’s satisfaction and sense of belonging. Data collected from an online survey with the participation of 898 IUH first-year students showed that students highly rated the quality of their lecturers’ teaching practices, the institutional support, and expressed their satisfaction with their entire learning experience. Data, however, indicated areas that needed improving. IUH first-year students did not make enough academic effort because of low levels of the coursework’s challenge. Moreover, the quantity and quality of the interactions between first-year students and other members of IUH were still low, which negatively affected students’ sense of belonging to the university. The study also pointed out factors positively correlated with students’ satisfaction and sense of belonging, including the institutional support, the quality of students’ relationships with socializing agents on campus, and the high quality of teaching practices. Based on these results, some suggestions were put forward to help IUH motivate first-year students to make more effort in their study; support and encourage students’ better integration with IUH learning environment; and increase students’ sense of belonging to the university.
<span lang="EN-US">We implement a solid-state reaction technique to make MAl<sub>2−x</sub>Si<sub>x</sub>O<sub>4−x</sub>N<sub>x</sub> (M = Ca, Sr, Ba) as well as its variant doped with Eu at 1300 – 1400°C in a nitrogen hydrogen environment. Then, we measure the solubility of (SiN)<sup>+</sup> in MAl<sub>2</sub>O<sub>4</sub>. By replacing (AlO)<sup>+</sup> with (SiN)<sup>+</sup>, whose solubility is dependent on M cations, nitrogen may be integrated into MAl<sub>2</sub>O<sub>4</sub>. (SiN)<sup>+ </sup>has poor solubility in CaAl<sub>2</sub>O<sub>4 </sub>(x ≈ 0.025) and SrAl2O4 lattices (x ≈ 0.045) but a considerable integrated quantity of (SiN)<sup>+ </sup>against BaAl<sub>2</sub>O<sub>4</sub> (x ≈ 0.6). Because of the low solubility of (SiN)<sup>+</sup>, incorporation of (SiN)<sup>+ </sup>barely affects the luminescence characteristics of MAl<sub>2</sub>O<sub>4</sub> when doped with Eu<sup>2+</sup> (M = Ca, Sr), resulting in discharges in green as well as blue at nearly constant wavelengths measured at 440 as well as 515 nm, respectively. With certain concentrations of (SiN)<sup>+ </sup>as well as Eu<sup>2+</sup>, Eu<sup>2+</sup>-doped BaAl<sub>2−x</sub>Si<sub>x</sub>O<sub>4−x</sub>N<sub>x</sub> emits one wide green discharge line under a maximum within the region 500 – 526 nm. Furthermore, once we add nitrogen, both the excitation as well as discharge lines for Eu2+ exhibit one substantial redshift. BaAl<sub>2−x</sub>Si<sub>x</sub>O<sub>4−x</sub>N<sub>x</sub>: Eu<sup>2+ </sup>is a compelling transmuting phosphor that can be utilized for WLED devices because of its efficient stimulation in the range of 390–440 nm radiation.</span>
The application of <span>quantum dots has been considered as a promising approach to the advancement of phosphor-converted light-emitting diodes (pc-LEDs) since they perform an excellent extinction coefficient. Yet, it is challenging to manage their influences on the optical properties of LEDs due to their different nanometers in size. Hence, the object of this research is to analyze the influences of quantum dot (QDs) to figure out the solution to control the enhancement of LED lighting performances. Particularly, the study worked on investigating the scattering and absorption features of titanium dioxide (TiO<sub>2</sub>) QDs. It demonstrated that the radiant efficiency and luminous stability of the TiO<sub>2</sub> QDs-converted LEDs (QC-LEDs) was inferior due to the strong light absorption and reabsorption occurring inside the LED packages. Additionally, it also presented low uniformity of color distribution because the scattering ability of QDs is weak. Therefore, reducing the concentration of QDs when adding to the LED structure seems to be possible to enhance the luminous output of QC-LEDs. We propose 0.05% wt. TiO<sub>2</sub> for white LED to reduce the illumination losing caused by re-absorbent and total internal backscattering, resulting in approximate 31% lumen improvement and high color rendering index (CRI) measured at about 85, at a high color temperature of 7500 K</span>.
The yellow phosphor Y<sub>3</sub>Al<sub>5</sub>O<sub>12</sub>:Ce<sup>3+ </sup>(YAG:Ce<sup>3+</sup>), which sees its most popular use in <span>white light-emitting diode (</span>wLEDs), possess an optical spectrum that lacks the red element. The following article will propose a fresh solution for this problem, which involves adjusting the properties of Ce<sup>3+ </sup>spectrum by using exterior dye particles of ATTO-Rho101, possessing dramatic, wide absorption within the zone of green-yellow spectrum of Ce<sup>3+</sup> emission and significant release of the red element. The globular YAG:Ce<sup>3+</sup>, which is micrometer and nanometer in size with significant dispersion (micro/nano-YAG:Ce<sup>3+</sup>) was created by employing an altered solvothermal technique. The YAG:Ce<sup>3+</sup> produced by said technique, along with the heated micro-YAG:Ce<sup>3+</sup> and commercial phosphors, were exteriorly covered with SiO<sub>2</sub> and immersed in dye at the same time. Effective radiant transmission/reabsorption from Ce<sup>3+</sup> within the YAG’s internal bowel to the dye particles of the exterior hull of SiO<sub>2</sub>, regardless of the phosphors’ size, was displayed in the YAG: Ce<sup>3+</sup>@SiO<sub>2</sub>+ dye powder amassed over the stimulation of the light of blue, which boosted the red element of it. The fluorescent microscope was considered an effective device intended for detecting the reabsorption event in grinded substances.
The effects of injecting TiO<sub>2</sub>nanoparticles with phosphorus silicone packing on white color light-emitting diodes (WLEDs) are examined. In WLED packages, the proposed approach may increase luminance emission by 2.7%, while the coordinated color temperature will increase by 39%. At the same time, the required phosphorus quantity will be lowered by 5% along with the joint temperature of 6.5°C. The modifications, which boost illuminating performance and also reduce temperature aggregation, are because of the packing material's increased illuminating dispersion efficiency or even refracting indices, along with lower illuminating reduction, for which colour fusing inside the parcels is responsible. Consequently, the results suggest improved-WLED lighting system performance makes the products more appropriate in solid-state lighting.
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