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In this paper, we are interested to study a nonlinear Volterra equation with conformable deriva- tive. This kind of such equation has various applications, for example physics, mechanical engineering, heat conduction theory. First, we show that our problem have a mild soltution which exists locally in time. Then we prove that the convergence of the mild solution when the parameter tends to zero.

This work reported the successful synthesis of ilmenite-spinel (1 − x)NiTiO3-xMnFe2O4 (x = 0, 0.05 and 0.10) composites by a simple sol-gel method. Phase formation of composites was analyzed by the X-ray diffraction method. All the synthesized samples formed diphasic ilmenite-ferrite composites without any trace of impurity or intermediate phase. The optical properties of synthesized composites were characterized by diffuse reflectance UV–visible spectroscopy. MnFe2O4 phase modified the optical band gap of NiTiO3 material and shifted its optical bandgap value toward lower energy. Ferroelectric and magnetic hysteresis loops were investigated at room temperature. The hysteresis loops indicated the typical ferromagnetic and ferroelectric nature of all composites at room temperature. In P-E loops, the remanent polarization (Pr ) and saturation polarization (Ps ) showed a slight increase in the sample with 5% MnFe2O4 phase addition. However, the lossy P-E loop was observed in the sample with the addition of 10% MnFe2O4. The presence of ferrite MnFe2O4 phase in NiTiO3 material enhanced the magnetic properties of NiTiO3 at room temperature. The M-H loops of NiTiO3-MnFe2O4 composites presented a ferromagnetic behavior with a dramatic increase in saturation magnetization with an increase of ferrite phase addition.

The Ni[Formula: see text]CoxTiO3[Formula: see text] solid solution powders were prepared by an aqueous sol–gel method. The structural, optical, magnetic and ferroelectric properties of NiTiO3 were investigated by X-ray diffraction, scanning electron microscope, UV–Vis absorption, vibration samples magnetometer and ferroelectric test system. The X-ray diffraction analysis revealed that prepared materials were in a single phase with rhombohedral structure with [Formula: see text] up to 1. The increasing Co content resulted in decreasing of tolerance factor and increasing of the lattice constant. The crystalline size increased with an increase of Co content. The optical bandgap value of solid solution increased from 2.23[Formula: see text]eV for NiTiO3 to 2.36[Formula: see text]eV for CoTiO3. The magnetic hysteresis loop results indicate that all samples showed paramagnetic state at room temperature. A correlation between magnetization values and composition of the materials was observed with magnetization values which increased with increasing of CoTiO3 content in solid solution. Ferroelectric polarization analysis showed that the polarization of the Ni[Formula: see text]CoxTiO3 solid solution depended on x value and reached the maximum with [Formula: see text].

A quantitative study was used in the study of the tendency to change drought indicators in Vietnam through the Ninh Thuan province case study. The research data are temperature and precipitation data of 11 stations from 1986 to 2016 inside and outside Ninh Thuan province. To do the research, the author uses a non-parametric analysis method and the drought index calculation method. Specifically, with the non-parametric method, the author uses the analysis, Mann-Kendall (MK) and Theil-Sen (Sen’s slope), and to analyze drought, the author uses the Standardized Precipitation Index (SPI) and the Moisture Index (MI). Two Softwares calculated in this study are ProUCL 5.1 and MAKENSEN 1.0 by the US Environmental Protection Agency and Finnish Meteorological Institute. The calculation results show that meteorological drought will decrease in the future with areas such as Phan Rang, Song Pha, Quan The, Ba Thap tend to increase very clearly, while Tam My and Nhi Ha tend to increase very clearly short. With the agricultural drought, the average MI results increased 0.013 per year, of which Song Pha station tended to increase the highest with 0.03 per year and lower with Nhi Ha with 0.001 per year. The forecast results also show that by the end of the 21st century, the SPI tends to decrease with SPI 1 being −0.68, SPI 3 being −0.40, SPI 6 being −0.25, SPI 12 is 0.42. Along with that is the forecast that the MI index will increase 0.013 per year to 2035, the MI index is 0.93, in 2050 it is 1.13, in 2075 it will be 1.46, and by 2100 it is 1.79. Research results will be used in policymaking, environmental resources management agencies, and researchers to develop and study solutions to adapt and mitigate drought in the context of variable climate change.

Genus Zanthoxylum L. comprises about 200 species distributed in Asia, Africa, Australia and North America [3]. In Vietnam, there are about 12 species belonging to genus Zanthoxylum [1]. Many species in this genus are used as medicine, as spices or sources of essential oils. The fruit of Zanthoxylum rhetsa (Roxb.) DC. (Vietnamese name: “Sẻn hoi”) was collected in Ha Quang district (Cao Bang province). Microscopical characteristics of the fruit were investigated using light microscope. From fruit of Z. rhetsa, the essential oil was obtained by hydrodistillation. The gas chromatography combined mass spectrometry (GC/MS) analyse of essential oil led to the identification 25 compounds, accounting for 98.72% of the total essential oil content. The main components are Sabinene (64.80%), Terpinen-4-ol (6.07%), β-Pinene (4.81%), α-Pinene (4.09%), 1.8-Cineol (2.49%) and β-Phellandrene (2.90%). The essential oil of Z. rhetsa strongly inhibited NO production, with IC50 value was 16.42 ng/ml. These results demonstrate that essential oils from the fruit of Z. rhetsa possesses excellent anti-inflammatory activity and thus have great potential in treatment of inflammation.

Background and Objective: The methylation of Ubiquitin C-Terminal Hydrolase L1 (UCHL1) gene has been reported in many human cancers including nasopharyngeal carcinoma (NPC). In Vietnam, the methylation of UCHL1 gene’s promoter in NPC has not been demonstrated yet. In this study, a systematic literature revision was carried out to summarize the current evidences about the frequencies of UCHL-1 gene’s promoter methylation in NPC for further application in Vietnamese population. Methods: A systematic literature analysis was conducted based on the comprehensive studies. Moreover, many bioinformatic tools such as Methprimer, TFsearch, IDT OligoAnalyzer 3.1 were used to predict the CpG islands, transcriptional factors, and to pick up the MSP (Methylation-Specific PCR) primers. Results: Total of three previous studies were summarized and accessed for eligibility from literature research. As the results, the average weight methylated frequencies were 72.4% and 13.0% for NPC and non-cancerous samples, respectively. The significant association between UCHL-1 promoter methylation and NPC with the OR of 10.459 (95% CI = 4.915 – 22.254, p < 0.001) and RR of 4.117 (95% CI = 1.958 – 6.645, p < 0.0001) based on the random effects model, was observed. Moreover, we were successful in predicting the CpG islands as well as identifying transcriptional factor binding sites which served as “hot spot” for ideal primer pick up and located in gene promoter. Conclusion: The methylation of UCHL-1 gene promoter was significantly associated and contributed to NPC developmentin which it could be further applied in evaluation of UCHL-1 gene promoter status in Vietnamese population.

Objectives Kaempferia daklakensis N.H.Tuan & N.D.Trong (local name Up dat) (Zingiberaceae) was collected at Ea So Nature Reserve, Ea Kar district, Daklak Province, Viet Nam and described as a new record for the country’s flora. Methods An essential oil with 0.99% yield (w/w) was extracted from the absolute dry rhizomes by steam distillation as a pleasant smelling yellow oil which was characterized by thin-layer chromatography (TLC) and Gas Chromatography- Mass Spectrometry (GC–MS) and evaluated its antibacterial activity against pathogenic bacteria by agar disk diffusion method. Results A total of 38 compounds (accounting for 67.3% of the total oil) were identified. The major components of the essential oils are α-pinene (2, 3.22%), camphene (3, 23.63%), camphor (10, 4.42%), borneol (12, 4.80%), isoborneol (17, 5.77%), ishwarane (21, 3.29%) and 1,8-cineole (8, 2.89%). K. daklakensis rhizome oil possessed inhibitory activity against Gram (+) and Gram (−) microbial strains including Bacillus subtilis, Bacillus cereus, Bacillus pumilus, Staphylococcus aureus, Shigella flexneri, Proteus mirabilis. Conclusions This results suggest that the essential oil of K. daklakensis rhizome could be used for the treatment of some infections by Gram(+) and Gram(−) microorganisms. This paper is considered also as an official announce for Kaempferia daklakensis species as a new record from Vietnam flora.

In this study, we have performed density functional theory based calculations to investigate the effect of alkali substituents M on the structure and electronic properties of (Bi0.5M0.5)TiO3 compounds with M = Li, Na and K. When the ionic radius of the substituting M cation increases, the corresponding direct band gap of (Bi0.5M0.5)TiO3 also increases. The same trend is found for the O-deficient Bi0.5M0.5TiO3-δ compounds, which were investigated by removing one Oxygen atom from the super cell creating an O-vacancy in it. The presence of the O-vacancy breaks the local symmetry of the crystal structures and generates excess electrons in the O-deficient compounds. This results in the appearance of an indirect bandgap in Bi0.5Na0.5TiO3-δ and Bi0.5K0.5TiO3-δ, except for Bi0.5Li0.5TiO3-δ that still exhibits a direct bandgap. Excess electrons induce the defect states within the original bandgap of the stoichiometric compounds and decrease the bandgap of the O-deficient compounds. In line with the electronic calculations, effective mass calculations have provided a preliminary insight into the photocatalytic performance of (Bi0.5M0.5)TiO3 and reveal a positive impact of K cations on the photocatalytic activity. Keywords: Bismuth – based perovskite, Alkali metals, Density functional theory, O-vacancies, Photocatalyst

This chapter discusses a case study based on six-week teacher placement in a bachelor program. The placement, which provides training to students who will become primary school teachers in the future, is treated at the same time as a research project in which data are collected from participants’ reflective journals. The purpose of the study is to serve the improvement of the program as much as it serves student learning. A cohort of 28 student teachers volunteered to participate in an eight-week placement. Their major task is to teach basic English to disadvantaged primary-school-age children in Thu Dau Mot suburban areas. The disadvantaged children include orphans, members of low-income families, and children with disruption or absence of schooling. Findings from the study reveal participants’ rich, hands-on experience with real-world challenges in bringing education to at-risk children, a deep understanding of multiple perspectives on the teaching profession, and insightful lessons from the everyday struggle to motivate children learning. Involving participants in the dual role of both teacher and researcher, the project demonstrates how a higher-education curriculum can be negotiated by the students themselves. The study also expands literacy practice by prioritizing new experience over current knowledge, by accepting student self-discovery over expert authority, and by constructing mutual support over the transfer of academic skills.

In this paper, the synthesis of nickel ferrite and its use for voltammetric determination of uric acid (UA) are presented. Nickel ferrite was synthesized via a hydrothermal process using spherical carbons as hard template followed by calcination at 500 °C. It was found that iron and nickel compositions in nickel ferrite can be controlled by the initial Fe/Ni molar ratio. The stoichiometric nickel ferrite (NiFe2O4) with hollow spherical morphology was obtained from a reaction mixture with Fe/Ni molar ratio of around 1.2–1.5. Glassy carbon electrode modified with nickel ferrite was employed to quantitatively determine UA by different pulse voltammetric method. Under the optimum conditions, the anodic peak current was linearly proportional to UA concentration in the range of 0.398 to 6.761 μM. The detection limit (3σ) was found to be 0.15 μM. The proposed method has been employed to determine UA in human urine samples with acceptable recoveries of 95.15–104.8%. On the other hand, the results obtained from this method were also compared with that from standard HPLC method, showing no statistical difference.

Combination in both ferroic properties in current lead-free ferroelectric materials is promising in creating a new type of smart electronic devices. In this report, single perovskite Co-doped 0.2BaZrO3-0.8BaTiO3 materials were synthesized by using the chemical method. The random incorporation of Co cations into the host lattice of 0.2BaZrO3-0.8BaTiO3 compounds resulted in distortion of the lattice parameter and strong reduction the optical band gap energy. Decreasing optical band gap energy was obtained from around 3.17 to 2.52 eV by introducing Co concentration of up to 9 mol.%. The magnetic properties of 0.2BaZrO3-0.8BaTiO3 compounds were showed in complex as dependent on the level of Co dopants. The nonlinear electrical polarization in 0.2BaZrO3-0.8BaTiO3 compounds was obtained and remained after the introduction of Co impurities. The observation in nonlinear in magnetism and electrical polarization were promised to transfer their materials for device applications.

Multiferroic materials based on lead-free ferroelectric materials have potential applications in the fabrication of next-generation devices. Herein, the sol–gel method is used to synthesize pristine and Cr-doped Bi0.5K0.5TiO3 nanocrystals. Density functional theory simulation is performed to elucidate the mechanism underlying the observed electronic and magnetic properties of the nanocrystals. In materials doped with 9 mol% Cr, the substitution of Cr in the Ti site decreases the optical band gap from 3.09 eV to 2.26 eV and induces ferromagnetism at room temperature. The saturation magnetization of the materials is approximately 0.18 μB/Cr at 5 K and can be attributed to the interplay of the unpaired electron counts of Cr3+ ions in the crystal field mechanism and Jahn–Teller effect. Pristine Bi0.5K0.5TiO3 samples exhibit weak ferromagnetism at room temperature, given the existence of the mixed valence states of Ti4+ and Ti3+ and the formation of O or Ti vacancies during sample growth. The present study provides deep insight into the induction of magnetism in ferroelectric materials doped with transition metals. Such materials have potential spintronic applications.

Pb-free ferroelectric solid solution of Bi0.5K0.5TiO3 with BiCoO3 has been fabricated using a sol-gel technique, exhibiting room-temperature ferromagnetism. The optical bandgap of Bi0.5K0.5TiO3 reduced from 3.21 eV to 1.77 eV with increasing amount of BiCoO3 solid solution. The room-temperature ferromagnetism and bandgap reduction occurred due to BiCoO3 diffusion into Bi0.5K0.5TiO3, resulting in formation of solid solution. These results provide a simple approach to realize room-temperature ferromagnetism in Pb-free ferroelectric materials.

Development the multiferroic materials based on the lead-free ferroelectric materials is the new possible channel to create the next generation devices. The pure Bi0.5K0.5TiO3 and Mn-doped Bi0.5K0.5TiO3 materials were synthesized using sol-gel method. While the substitution of Mn for Ti site reduces the optical band gap in Bi0.5K0.5TiO3, the room temperature ferromagnetism is obtained in both un-doped and Mn-doped Bi0.5K0.5TiO3 materials. By means of the first-principles calculations, the ferromagnetism in Mn-doped Bi0.5K0.5TiO3 materials can be explained by the mixed valence states of Mn ions through the crystal field mechanism and that in un-doped Bi0.5K0.5TiO3 materials is ascribed to the formation of O or Ti vacancies during the sample growth.

In this paper, we find a regularized approximate solution for an inverse problem for Burgers’ equation. The solution of the inverse problem for Burgers’ equation is ill-posed, i.e., the solution does not depend continuously on the data. The approximate solution is the solution of a regularized equation with randomly perturbed coefficients and randomly perturbed final value and source functions. To find the regularized solution, we use the modified quasi-reversibility method associated with the truncated expansion method with nonparametric regression. We also investigate the convergence rate.

In the present article, the application of activated carbon derived from rice husks (RHAC) with high surface area as an electrode modifier for electrochemical determination of chloramphenicol (CP) is demonstrated. The RHAC was synthesized via a two-step alkaline pretreatment followed by the application of ultrasound radiation. The obtained carbon materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption/desorption isotherms, Fourier transformation Infrared (FT-IR) spectroscopy and Raman spectroscopy. It was found that the ultrasonic activation process plays a critical role in improving the textural properties of AC by removing fine particles to clean capillaries and transforming a graphitic structure to a turbostratic one. The RHAC synthesized in suitable conditions displayed a specific surface area up to 1710 m2g−1. The glassy carbon electrode modified with RHAC exhibited an excellent electroactivity towards CP as compared to bare GCE. The voltammetry characteristics of the electrochemical sensor were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). This electrode had a good performance with a linear response range of 0.95–5.76μM and a low detection limit of 0.66μM (S/N = 3). The present promising sensor displayed high selectivity, great stability and expectable recovery for CP detection in real samples.