STRUCTURAL, VIBRATIONAL, OPTICAL, AND MAGNETIC PROPERTIES OF 0-3 TYPE PARTICULATE PbTiO3-NiFe2O4 COMPOSITES

We synthesized 0-3 type (1-x)PbTiO3-xNiFe2O4 (x = 0.0-0.5) multiferroic composites with two independently crystallized parent phases by the sol-gel method. Structural, surface morphology, vibrational, optical, and magnetic characteristics were investigated by X-ray diffraction (XRD), SEM, Raman scattering, UV-vis absorption, and magnetization (M-H) measurements, respectively. The XRD result showed that the lattice parameter a of the PbTiO3 (PTO) phase decreased while lattice parameter c increased after compositing, leading to a decrease in the tetragonal ratio c/a. SEM images indicated that the NiFe2O4 (NFO) crystals that crystallized later are small and adhere to the surface of the large PTO particles. The strong cohesion between the two components was also revealed by the gradual shift of the Raman peaks to the lower wavelength and the reduction of the Raman intensity as the NFO content increased. The UV-vis absorption result showed the co-absorption spectra of the parent phases in the composites. Magnetization curves presented a sharp increase in saturation magnetization MS with NFO content from 0.014 emu/g for the PTO sample to 14.360 emu/g for the composite containing 50 mol% NFO. This study indicates an effective method in the search for multilayer composites

Exploiting Idioms and Proverbs of Vietnamese Regions in Teaching Mathematics in Primary Schools

Mathematics and idioms, as well as proverbs, all reflect the laws of life. At the same time, primary school children may have heard idioms and proverbs before attending school. Therefore, there are many possibilities to exploit and apply idioms and proverbs in teaching mathematics in primary schools. This study aims to identify appropriate situations and apply idioms and proverbs in different regions of Vietnam to teaching mathematics. The researchers selected 1155 expressions related to mathematics from many typical pieces of research on idioms and proverbs in Vietnam. After surveying 1822 teachers three times in many provinces and cities in all 3 regions of Vietnam: the North, the Central and the South, the researchers have classified the data according to the criteria from closed to open-ended questions. The results show a prominent level of interest (level 4/5) of all teachers participating in the survey, and there is no difference in the effectiveness in the three regions, but there is a clear difference in regions in using idioms and proverbs. Particularly, identifying situations to teach geometric and quantitative knowledge, as well as probability and statistics, allows one to apply idioms and proverbs at a high level. It is concluded that if idioms and proverbs from Vietnamese regions are appropriately selected and applied in teaching mathematics in primary schools, they will contribute to improving students' mathematical ability and preserving the national cultural heritage. Doi: 10.28991/ESJ-2022-SIED-015 Full Text: PD

Investigation of Sodium Manganese Oxide Nanowires Synthesized by Hydrothermal Method for Alkaline Ion Battery

Sodium Manganese Oxide (NaxMnO2) has attracted much attention as cathode materials for alkaline ion battery due to the ability of fast charge and discharge ion Na+, in particular in nanoscale. We report on the synthesis of NaxMnO2 nanowires via hydrothermal synthesis route from Mn2O3 and NaOH solution. The morphological observation indicates that the obtained Na0.44MnO2 nanowires with diameters of about 20-30 nm, length up to several micrometers were formed by this process. The electrochemical properties of fabricated materials were investigated by means of cyclic voltammetry technique and show that Sodium Manganese Oxide (NaxMnO2) is a promising material in the field of research and fabrication alkaline ion battery

Objectively measured physical activity of Vietnamese adults with type 2 diabetes: Opportunities to intervene

Objectives: To objectively determine and compare the physical activity (PA) levels of adults newly diagnosed with type 2 diabetes (T2D) and adults without T2D in Vietnam using an accelerometer. Methods: A total of 120 participants with newly diagnosed T2D and 120 adults without T2D were recruited from a large hospital in Hanoi, the capital city of Vietnam. All participants wore an ActiGraph GT3X accelerometer for at least 5 days, including 1 weekend day. Freedson cut-off points were used to estimate different intensities of PA. In addition, comparisons between groups were made with respect to achieving the World Health Organization (WHO) and International Diabetes Federation (IDF) recommended PA guidelines. Results: Men with T2D had significantly lower levels of PA than men without T2D. The respective multivariable-adjusted mean values of daily step count, daily light-intensity, moderate-intensity, and moderate-to-vigorous-intensity PA were approximately 14%, 19%, and 22% lower in the men with T2D than in their non-T2D counterparts. However, women with T2D accumulated a greater number of steps per day than women without T2D. Only 59.2% of the adults with T2D met the minimum recommended level of PA (WHO and IDF), compared to 74.2% of adults without T2D (p<0.05). After adjusting for potential confounders, participants with T2D experienced 50.0% significantly lower odds of achieving PA recommendations. Conclusions: Vietnamese men with T2D were less physically active than those without T2D, and adults with T2D were less likely to meet PA guidelines. The results suggest a need for integrating PA into the self-management of this chronic condition

Preparation and Inverstigation of MEH-PPV Films Used for White Light Emitting Diodes

With the aim to prepare white Light Emitting Diode (WLED), the conjugate polymer films like (Poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) were investigated. Spectroscopic (absorption and emission) spectra of the MEH-PPV films showed that this polymer is suitable for casting onto the chips of the blue InGaN LED to make WLED. The luminous flux measured on the WLEDs in the integrating sphere proved that the white light emission can be obtained from the combination of inorganic LED and conjugate (MEH-PPV) polymers with an optimal thickness and a high quality. The aging process of MEH-PPV films was found to be strongly dependent post-treatment conditions. Reasonable heat treatment condition for the MEH-PPV polymers was suggested as in vacuum of 5×10-2 Pa at a temperature of 120°C in, for 2 hous

Organic - Inorganic Hybrid Luminescent Composite for Solid-state Lighting

White light emitting diodes (WLEDs) made by coating organic and inorganic hybrid composites on blue LED chips. Y3Al5O12:Ce (YAG:Ce) nano inorganic powder prepared by low-temperature Sol-Gel method exhibited broad green emission with the peak at 521 nm. Poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) polymer has high luminescence efficiency and red emission peak at 590 nm. The white light was obtained by mixing blue light from emission of the blue LED chip - Indium Gallium Nitride (InGaN) and green-red light from the fluorescence of nano- YAG:Ce and MEH-PPV polymer hybrid composite. The hybrid nanocomposite-based WLEDs exhibited broad band emission spectra from blue light to red wavelengths and provided the white light with a CIE-1931 coordinate of x = 0.2986, y = 0.2620 and a colour rendering index Ra = 84.36. The results suggest a potential application of nanocomposite based WLEDs in efficient solid-state lighting

Model binding experiments with cucurbit[7]uril and p-sulfonatocalix[4]arene support use of explicit solvation term in governing equation for binding equilibria

The thermodynamics of model host–guest-binding reactions is examined in depth using isothermal titration calorimetry. In conflict with classical thermodynamics, the results indicate that the equilibrium-binding quotient, K, is not a constant for all pairings. This outcome is predicted by an equation for binding equilibria that includes an explicit term for the change in solvation free energy that accompanies the formation of a binary complex. Application of this framework to the experimentally observed concentration dependence of K allows one to obtain the energetic contribution of the solvent, a linked equilibrium denoted here as ΔGH2O. The estimated values of ΔGH2O are large and unfavourable for the binding of selected guest molecules to two hosts, cucurbit[7]uril and p-sulfonatocalix[4]arene. Intriguingly, the estimated values of ΔGH2O are near zero for the binding of two hydrophobic guest molecules to β-cyclodextrin, leading to a thought-provoking discussion on the driving force behind the hydrophobic effect

Genomic serotyping, clinical manifestations, and antimicrobial resistance of non-typhoidal Salmonella gastroenteritis in hospitalized children in Ho Chi Minh City, Vietnam

Nontyphoidal Salmonella (NTS) are among the most common etiological agents of diarrheal diseases worldwide and have become the most commonly detected bacterial pathogen in children hospitalized with diarrhea in Vietnam. Aiming to better understand the epidemiology, serovar distribution, antimicrobial resistance (AMR), and clinical manifestation of NTS gastroenteritis in Vietnam, we conducted a clinical genomics investigation of NTS isolated from diarrheal children admitted to one of three tertiary hospitals in Ho Chi Minh City. Between May 2014 and April 2016, 3,166 children hospitalized with dysentery were recruited into the study; 478 (∼15%) children were found to be infected with NTS by stool culture. Molecular serotyping of the 450 generated genomes identified a diverse collection of serogroups (B, C1, C2 to C3, D1, E1, G, I, K, N, O, and Q); however, Salmonella enterica serovar Typhimurium was the most predominant serovar, accounting for 41.8% (188/450) of NTS isolates. We observed a high prevalence of AMR to first-line treatments recommended by WHO, and more than half (53.8%; 242/450) of NTS isolates were multidrug resistant (MDR; resistant to ≥3 antimicrobial classes). AMR gene detection positively correlated with phenotypic AMR testing, and resistance to empirical antimicrobials was associated with a significantly longer hospitalization (0.91 days; P = 0.04). Our work shows that genome sequencing is a powerful epidemiological tool to characterize the serovar diversity and AMR profiles in NTS. We propose a revaluation of empirical antimicrobials for dysenteric diarrhea and endorse the use of whole-genome sequencing for sustained surveillance of NTS internationally

Molecular Engineering Using an Anthanthrone Dye for Low-Cost Hole Transport Materials: A Strategy for Dopant-Free, High-Efficiency, and Stable Perovskite Solar Cells

In this report, highly efficient and humidity-resistant perovskite solar cells (PSCs) using two new small molecule hole transporting materials (HTM) made from a cost-effective precursor anthanthrone (ANT) dye, namely, 4,10-bis(1,2-dihydroacenaphthylen-5-yl)-6,12-bis(octyloxy)-6,12-dihydronaphtho[7,8,1,2,3-nopqr]tetraphene (ACE-ANT-ACE) and 4,4′-(6,12-bis(octyloxy)-6,12-dihydronaphtho[7,8,1,2,3-nopqr]tetraphene-4,10-diyl)bis(N,N-bis(4-methoxyphenyl)aniline) (TPA-ANT-TPA) are presented. The newly developed HTMs are systematically compared with the conventional 2,2′,7,7′-tetrakis(N,N′-di-p-methoxyphenylamino)-9,9′-spirbiuorene (Spiro-OMeTAD). ACE-ANT-ACE and TPA-ANT-TPA are used as a dopant-free HTM in mesoscopic TiO2/CH3NH3PbI3/HTM solid-state PSCs, and the performance as well as stability are compared with Spiro-OMeTAD-based PSCs. After extensive optimization of the metal oxide scaffold and device processing conditions, dopant-free novel TPA-ANT-TPA HTM-based PSC devices achieve a maximum power conversion efficiency (PCE) of 17.5% with negligible hysteresis. An impressive current of 21 mA cm−2 is also confirmed from photocurrent density with a higher fill factor of 0.79. The obtained PCE of 17.5% utilizing TPA-ANT-TPA is higher performance than the devices prepared using doped Spiro-OMeTAD (16.8%) as hole transport layer at 1 sun condition. It is found that doping of LiTFSI salt increases hygroscopic characteristics in Spiro-OMeTAD; this leads to the fast degradation of solar cells. While, solar cells prepared using undoped TPA-ANT-TPA show dewetting and improved stability. Additionally, the new HTMs form a fully homogeneous and completely covering thin film on the surface of the active light absorbing perovskite layers that acts as a protective coating for underlying perovskite films. This breakthrough paves the way for development of new inexpensive, more stable, and highly efficient ANT core based lower cost HTMs for cost-effective, conventional, and printable PSCs

Excess body weight and age associated with the carriage of fluoroquinolone and third-generation cephalosporin resistance genes in commensal Escherichia coli from a cohort of urban Vietnamese children.

PURPOSE: Antimicrobial-resistant bacterial infections in low- and middle-income countries (LMICs) are a well-established global health issue. We aimed to assess the prevalence of and epidemiological factors associated with the carriage of ciprofloxacin- and ceftriaxone-resistant Escherichia coli and associated resistance genes in a cohort of 498 healthy children residing in urban Vietnam. METHODOLOGY: We cultured rectal swabs onto MacConkey agar supplemented with resistant concentrations of ciprofloxacin and ceftriaxone. Additionally, we screened meta-E. coli populations by conventional PCR to detect plasmid-mediated quinolone resistance (PMQR)- and extended-spectrum β-lactamase (ESBL)-encoding genes. We measured the associations between phenotypic/genotypic resistance and demographic characteristics using logistic regression.Results/Key findings. Ciprofloxacin- and ceftriaxone-resistant E. coli were cultured from the faecal samples of 67.7 % (337/498) and 80.3 % (400/498) of children, respectively. The prevalence of any associated resistance marker in the individual samples was 86.7 % (432/498) for PMQR genes and 90.6 % (451/498) for β-lactamase genes. Overweight children were significantly more likely to carry qnr genes than children with lower weight-for-height z-scores [odds ratios (OR): 1.24; 95 % confidence interval (CI): 10.5-1.48 for each unit increase in weight for height; P=0.01]. Additionally, younger children were significantly more likely to carry ESBL CTX-M genes than older children (OR: 0.97, 95 % CI: 0.94-0.99 for each additional year, P=0.01). CONCLUSION: The carriage of genotypic and phenotypic antimicrobial resistance is highly prevalent among E. coli in healthy children in the community in Vietnam. Future investigations on the carriage of antimicrobial resistant organisms in LMICs should focus on the progression of carriage from birth and structure of the microbiome in obesity