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STRUCTURAL, FERROELECTRIC AND ELECTRICAL-FIELD-INDUCED PIEZOELECTRIC PROPERTIES OF PbTiO3-MODIFIED COMPLEX 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 MATERIALS pbtio3修饰配合物0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3材料的结构、铁电和电场致压电性能
Pub Date : 2022-06-01 DOI: 10.18173/2354-1059.2022-0024
T. Nguyen Hoang, Duong Nguyen Xuan, Lam Nguyen Huu, Bac Luong Huu, Vinh Pham Van, Trung Nguyen Ngoc, Duc Nguyen Van, Dung Nguyen Duc
Complex ferroelectric PbTiO3-modified 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 materials were synthesized by a conventional solid-state reaction method. The addition of PbTiO3 into host 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 materials are modified the ferroelectric properties of host materials where the maximum polarization slightly increased from 23.09 Ccm2 to 23.28 Ccm2 and the remnant polarization is found to increase from 10.07 Ccm2 to 11.31 Ccm2. The large piezoelectric dynamic coefficient value of 662 pmV is obtained for 7 mol. % PbTiO3 modified 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 compounds as solid solution. Our work is expected to contribute to the role of A-site modification in lead-free ferroelectric BaTiO3-based materials for advanced function materials for electronic device applications.
采用常规固相反应法制备了pbtio3修饰的铁电复合材料0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3。在0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3基体材料中加入PbTiO3后,基体材料的铁电性能发生了变化,最大极化从23.09Ccm2略微增加到23.28Ccm2,残余极化从10.07Ccm2增加到11.31Ccm2。以7 mol. % PbTiO3改性的0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3为固溶体,获得了较大的压电动态系数662 pmV。我们的工作有望在无铅铁电batio3基材料中发挥a位修饰的作用,用于电子器件应用的高级功能材料。
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引用次数: 0
SCREENING YEAST FROM NATURAL HONEY, AND BEESWAX IN SON LA PROVINCE FOR LOW-ALCOHOL MEAD PRODUCTION 从山东省天然蜂蜜和蜂蜡中筛选酵母用于低酒精蜂蜜酒的生产
Pub Date : 2022-06-01 DOI: 10.18173/2354-1059.2022-0031
Nam Nguyen Hoang, Thanh Phan Due, Thuy Tran Thi
Son La is a northern mountainous province of Vietnam, where the climate and soil are suitable for various flowering plants and for many honey bee species to grow and produce high-quality honey. Yeasts in honey are expected to have valuable characteristics that can be applied in many fields. In this paper, seventy-two yeast strains isolated from natural honey and beeswax in Son La were screened for the ability of alcoholic fermentation to produce mead. Screening yeast strains for lowalcohol mead production were carried out based on the fermentation ability and the sensory of the final mead product. Yeast train NT95 was selected and characterized as Zygosaccharomyces sp. NT95. A suitable condition for the growth of Zygosaccharomyces sp. NT95 was Hansen broth containing a sugar concentration of 60 - 90 gL at pH 4.0 - 4.5, and a temperature of 30 °C. A suitable condition for the alcoholic fermentation of Zygosaccharomyces sp. NT95 in the honey medium was at 30 °C with the inoculum of 5 x 107 cellsmL for 18 days. Under this condition, the mead produced by Zygosaccharomyces sp. NT95 contained approximately 4.5% alcohol (vv) and the sensory score reached 14.51 ± 0.15 points. Further studies need to be done to improve the fermentation process and the completion of the product.
山萝是越南北部的一个多山省份,那里的气候和土壤适合各种开花植物和许多蜜蜂种类生长和生产高质量的蜂蜜。蜂蜜中的酵母有望具有可应用于许多领域的有价值的特性。本文对从松腊天然蜂蜜和蜂蜡中分离的72株酵母菌进行了酒精发酵生产蜂蜜酒的能力筛选。根据低醇蜂蜜酒的发酵能力和最终产品的感官,筛选生产低醇蜂蜜酒的酵母菌株。选择酵母菌株NT95,鉴定为Zygosaccharomyces sp. NT95。适宜Zygosaccharomyces sp. NT95生长的条件是:pH为4.0 ~ 4.5,Hansen培养基中糖浓度为60 ~ 90g / L,温度为30℃。Zygosaccharomyces sp. NT95在蜂蜜培养基中酒精发酵的适宜条件为30℃,接种量为5 × 107个细胞/ mL,发酵18天。在此条件下,Zygosaccharomyces sp. NT95生产的蜂蜜酒酒精含量约为4.5% (vv),感官评分为14.51±0.15分。需要进一步的研究来改进发酵工艺和产品的完成度。
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引用次数: 0
INVESTIGATION OF I-V CHARACTERISTICS OF CARBON NANOTUBES AND TIN OXIDE NANOWIRES HETEROJUNCTION FOR GAS SENSING APPLICATIONS 气敏用碳纳米管和氧化锡纳米线异质结的i-v特性研究
Pub Date : 2022-06-01 DOI: 10.18173/2354-1059.2022-0026
Nguyet Quan Thi Minh, Hoa Tran Thi Ngoc, Duy Nguyen Van, H. Nguyen Duc, Hieu Nguyen Van
In this study, heterojunctions of carbon nanotubes (CNTs) and tin oxide nanowires (SnO2) were investigated to determine their electrical performance for gas sensing applications. The I–V characteristics of the heterojunction were measured in air and H2S gas. The electrical parameters such as barrier height ϕB, ideality factor n, series resistance Rs, and reverse saturation current Io were extracted from the I-V plots. In H2S gas, the barrier height ϕB and series resistance Rs are lower compared to air, whereas the ideality factor n and saturation current Io are higher. These findings are essential for promoting technologies aimed at forming high-quality heterojunctions for gas sensing applications.
在这项研究中,研究了碳纳米管(CNTs)和氧化锡纳米线(SnO2)的异质结,以确定它们在气敏应用中的电性能。在空气和H2S气体中测量了异质结的I-V特性。从I-V图中提取栅极高度b、理想因数n、串联电阻r和反向饱和电流Io等电学参数。在H2S气体中,阻挡高度(ϕB)和串联电阻(Rs)比空气低,而理想因数(n)和饱和电流(Io)比空气高。这些发现对于促进形成高质量异质结用于气敏应用的技术至关重要。
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引用次数: 0
PARTICULATE MATTER LEVELS AND ELEMENTAL COMPOSITION IN THE SPRING AND TRANSITION PERIOD IN HANOI, VIETNAM 越南河内市春季和过渡时期颗粒物水平和元素组成
Pub Date : 2022-06-01 DOI: 10.18173/2354-1059.2022-0028
Manh Hoang Van, Thuy Ly Bich, Loc Nguyen Dac, T. Nguyen Minh, Anh Van Dieu, Giang Ton Thu, Hiền Nguyễn Thị Thu, Ha Vo Thi Le
Particulate matter (PM) is a major environmental concern in Vietnam as well as in the world. Samples of PM2.5, PM10, and total suspended particle (TSP) were collected on the rooftop of a five-floor building inside Hanoi University of Science and Technology, Hanoi, from January to May 2015. The levels PM2,5, PM10, and the metal elements of TSP were determined. PM2,5 and PM10 had average concentrations of 73 ± 37 and 138 ± 67 μgm3, respectively. The concentration of PM2,5 and PM10 in all samples were higher than the recommended level in the World Health Organization (WHO) guideline (2005) for 24h and annual concentrations of 25 and 50 μgm3, respectively. Nineteen elements detected in TSP samples included the higher concentration group in order: Ca > Fe > Na > Al > Mg > K > Zn and in the lower concentration group: Pb > Mn > Ti > Sr > V > Cr > Cd. The potential sources revealed from element components were discussed.
微粒物质(PM)是越南乃至世界的一个主要环境问题。2015年1月至5月,在河内科技大学一栋五层楼的屋顶上采集了PM2.5、PM10和总悬浮颗粒(TSP)样本。测定了PM2、pm5、PM10及TSP中金属元素的含量。PM2、pm5和PM10的平均浓度分别为73±37和138±67 μgm3。所有样本的PM2、pm5和PM10浓度均高于世界卫生组织(WHO)指南(2005)建议的24小时和年浓度水平,分别为25和50 μgm3。TSP样品中检出19种元素,浓度较高组为Ca > Fe > Na > Al > Mg > K > Zn,浓度较低组为Pb > Mn > Ti > Sr > V > Cr > Cd。
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引用次数: 0
ENHANCE A PHOTOCATALYTIC ACTIVITY ON Ag3PO4 BY AgAg3PO4 COMPOSITES AgAg3PO4复合材料增强Ag3PO4的光催化活性
Pub Date : 2022-06-01 DOI: 10.18173/2354-1059.2022-0025
Hung Nguyen Manh, Than Dao Viet, Thuy Nguyen Thi Dieu, Anh Ho Quynh, Khang Nguyen Cao, Oanh Le Thi Mai, Chung Pham Do, Nhung Nguyen Thi, Hang Lam Thi
In this study, we investigated the formation and influence of Ag particles on the physical properties and photocatalytic performance of Ag3PO4 photocatalysts when Ag particles adhered to the Ag3PO4 surface. The material is prepared by a simple precipitation method with illumination. The properties of the materials were investigated by X-ray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM), UV-vis absorption, and the photocatalytic ability to decompose organic solutions. The results show the vibrational change of the [PO4] group in the structure presented in the Raman scattering spectrum highest RhB decomposition. The experimental results indicated that the AgAg3PO4 showed highly efficient and stable photocatalytic activity under visible light irradiation. The AgAg3PO4 sample with the Ag+PO43- the ratio of 3.61 gave efficiency when stimulated with visible light of Xenon lamps. This sample degraded almost completely to RhB in 10 ppm solution after 15 min of illumination, with a decomposition rate of 0.241 min-1.
在本研究中,我们研究了Ag颗粒附着在Ag3PO4表面时,Ag颗粒的形成及其对Ag3PO4光催化剂物理性能和光催化性能的影响。该材料是用光照下的简单沉淀法制备的。通过x射线衍射(XRD)、拉曼散射(Raman scattering)、扫描电镜(SEM)、紫外可见吸收(UV-vis)以及光催化分解有机溶液的能力对材料的性能进行了研究。结果表明,结构中[PO4]基团的振动变化呈现在喇曼散射光谱最高的RhB分解处。实验结果表明,AgAg3PO4在可见光照射下表现出高效稳定的光催化活性。Ag+PO43-比值为3.61的AgAg3PO4样品在氙灯可见光刺激下具有较高的效率。光照15分钟后,样品在10ppm溶液中几乎完全降解为RhB,分解速率为0.241 min-1。
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引用次数: 0
PREDICTING ELASTIC MODULUS OF THE BODY-CENTERED CUBIC METALLIC FILMS 体心立方金属薄膜弹性模量的预测
Pub Date : 2022-06-01 DOI: 10.18173/2354-1059.2022-0023
Phuong Duong Dai
The elastic modulus of the body-centered cubic (BCC) films is studied based on the moment method. For Fe, Ta, and W films a clear elastic modulus dependence of the thickness at ambient conditions and under temperatures up to 2000 K. The obtained results of the values of elastic modulus metallic films are smaller than the corresponding values of bulk material. Calculated results show the effects of temperature and thickness of elastic modulus for Fe, Ta, and W metallic films. On the other hand, when the thickness of thin films is about 60nm then the elastic modulus of the BCC films approaches the values of bulk material. Our results are compared with the other theoretical results and experimental values of bulk materials.
基于矩量法研究了体心立方(BCC)薄膜的弹性模量。对于Fe, Ta和W薄膜,在环境条件下和温度高达2000k时,厚度的弹性模量明显依赖。所得金属薄膜的弹性模量值小于块状材料的相应值。计算结果表明温度和厚度对Fe、Ta和W金属薄膜弹性模量的影响。另一方面,当薄膜厚度约为60nm时,BCC薄膜的弹性模量接近块体材料的弹性模量。我们的结果与其他的理论结果和实验值进行了比较。
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引用次数: 0
THE SEMILINEAR COUPLED SYSTEMS FOR THE EXTERNAL DAMPING MODELS WITH VARIABLE COEFFICIENTS 变系数外阻尼模型的半线性耦合系统
Pub Date : 2022-06-01 DOI: 10.18173/2354-1059.2022-0018
Duong Pham Trieu
We present in this article some results on the global solvability with arbitrarily small data of the Cauchy problem for the following semilinear coupled system with a variable coefficient utt + a(x)(−∆)σu + ut = F(|D|αv, vt), vtt + a(x)(−∆)σv + vt = G(|D|αu, ut), u(0, x) = u0(x), ut(0, x) = u1(x), v(0, x) = v0(x), vt(0, x) = v1(x). The nonlinearities are of the form (F, G) = (||D|αv|p, ||D|αu|q), or (F, G) = (|vt|p, |ut|q), and the parameter σ satisfies σ ∈ (0, 1). We will show that the ”critical exponents” p, q for the small data global solvability have a close relation to the established exponents of the corresponding semilinear problems for the external damping equations.
本文给出了一类具有变系数utt + a(x)(−∆)σu + ut = F(|D|αv, vt)、vtt + a(x)(−∆)σv + vt = G(|D|αu, ut)、u(0, x) = u0(x)、ut(0, x) = u1(x)、v(0, x) = v0(x)、vt(0, x) = v1(x)的半线性耦合系统的柯西问题在任意小数据下的全局可解性的一些结果。非线性形式为(F, G) = (||D|αv|p, ||D|αu|q)或(F, G) = (|vt|p, |ut|q),参数σ满足σ∈(0,1)。我们将证明小数据全局可解性的“临界指数”p, q与相应的半线性外阻尼方程的指数有密切的关系。
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引用次数: 0
ASSESSING THE METEOROLOGICAL DROUGHT LEVEL IN THAI NGUYEN PROVINCE 评估太原省的气象干旱程度
Pub Date : 2022-06-01 DOI: 10.18173/2354-1059.2022-0033
Thuy Hoang Luu Thu, Dung Le Gia, Cuc Pham Thi, Vu Vuong Van, M. Tran Thi, Tuan Tong Phuc, Hanh Le Duc, Huong Do Thi Van
The study aims to assess the degree of drought in Thai Nguyen province by using two indices including (i) the K drought index, and (ii) the Sazonov drought index (Sa.I). According to the value of Kn, the north of the province is sufficiently moist, while the plain region (the center and the south of the province) is dry (Kn= 2.6). The Sa.I index is used to assess the evolution of the drought levels in the region in the period 1961 - 2020. Drought tends to increase throughout the region. The value of Sa.I index fluctuates from -4 to 3 with the year frequency of drought occurrence accounting for 27.5%, of which 12.5% is severe. The assessment results on the degree of meteorological drought in Thai Nguyen province are the scientific basis for the arrangement and restructuring of the crop in agricultural production and making important contributions to the prevention and mitigation of drought natural disasters.
采用K干旱指数和saazonov干旱指数(Sa.I)对太原省的干旱程度进行评价。由Kn值可知,该省北部较为湿润,平原地区(省中部和省南部)较为干燥(Kn= 2.6)。Sa。利用I指数评价1961 - 2020年区域干旱程度的演变。整个地区的干旱情况趋于加剧。Sa的值。I指数在-4 ~ 3之间波动,干旱发生年频次占27.5%,其中重度占12.5%。太原省气象干旱程度评价结果是农业生产作物安排和调整的科学依据,为预防和缓解干旱自然灾害做出了重要贡献。
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引用次数: 0
NONLINEAR DEFORMATION OF Au, AuSi AND AuCuSi WITH FCC STRUCTURE UNDER PRESSURE 具有FCC结构的Au, AuSi和AuCuSi在压力下的非线性变形
Pub Date : 2022-06-01 DOI: 10.18173/2354-1059.2022-0021
Hoc Nguyen Quang, Hien Nguyen Duc
On the basis of the model and the theory of nonlinear deformation for FCC substitutional and interstitial ternary alloy built by the statistical moment method, we perform numerical calculations for Au, AuSi, and AuCuSi. Some calculated results on the nonlinear deformation of Au obtained by SMM have been compared with the experimental data and have some very good concordance. Many calculated numerical results on nonlinear deformation of AuSi and AuCuSi are new and predictive, experimentally oriented
基于基于统计矩法建立的FCC取代型和间隙型三元合金非线性变形模型和理论,对Au、AuSi和AuCuSi进行了数值计算。本文对用SMM法得到的金的非线性变形计算结果与实验数据进行了比较,得到了很好的一致性。许多关于AuSi和AuCuSi非线性变形的数值计算结果是新的、预测的、实验导向的
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引用次数: 0
BATS OF LY SON ARCHIPELAGO, CENTRAL VIETNAM 越南中部ly son群岛的蝙蝠
Pub Date : 2022-06-01 DOI: 10.18173/2354-1059.2022-0030
Thong Vu Dinh
Ly Son is a small but important archipelago of Vietnam. It contains different ecosystems ranging from urbanized to natural vegetation. However, little was known about bats and the general biodiversity of this archipelago. In August 2017 and May 2022, the author conducted a series of bat surveys throughout the archipelago. Bats were captured using mist nets and harp traps. Echolocation calls were recorded using the PCTape system at every netting and trapping site and inside a flight tent. Recorded calls were analyzed using the Selena software. Results from the survey confirmed that the Ly Son archipelago is home to two bat species belonging to two genera, two families: Pteropodidae (Cynopterus sphinx) and Vespertilionidae (Myotis muricola). Of these two species, C. sphinx was very common while M. muricola was rarely recorded in the archipelago. Remarkably, the echolocation signal duration of M. muricola is in a range of 2.6-5.2 milliseconds which is longer than descriptions in previous publications.
黎山是越南的一个小而重要的群岛。它包含不同的生态系统,从城市化到自然植被。然而,人们对蝙蝠和这个群岛的总体生物多样性知之甚少。2017年8月和2022年5月,作者在整个群岛进行了一系列蝙蝠调查。用雾网和竖琴捕捉蝙蝠。回声定位呼叫使用PCTape系统记录在每个网和诱捕点和飞行帐篷内。使用Selena软件分析了通话记录。调查结果证实,Ly Son群岛是两种蝙蝠的家园,属于两科两属:翼足科(Cynopterus sphinx)和狐蝠科(Myotis muricola)。在这两个物种中,C. sphinx非常常见,而M. muricola在群岛上很少记录。值得注意的是,M. muricola的回声定位信号持续时间在2.6-5.2毫秒之间,比以前的出版物描述的要长。
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引用次数: 0
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