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Synthesis, Characterization and Photocatalytic Application of Different Sizes of Gold Nanoparticles on 4-Nitrophenol 不同尺寸金纳米颗粒在4-硝基苯酚上的合成、表征及光催化应用
Pub Date : 2016-07-05 DOI: 10.4236/WJNSE.2016.63012
R. Seoudi, F. Al-Marhaby
In this work, different sizes of gold nanoparticles were synthesized at room temperature by using trisodium citrate as a surfactant stabilizing agent and sodium borohydride as a reducing agent. Transmission Electron Microscopy (TEM) confirmed that the samples were synthesized in spherical shapes with three different particle sizes: 4 nm, 7 nm and 11 nm. Ultraviolet-visible spectra measurements were used to analyze the way that surface plasmon bands were affected by the different particles sizes. The effect of sphere size on photocatalytic reduction of 4-Nitrophenol was then studied and the rate constant of the reduction was calculated to be 0.014 s-1, 0.0091 s-1 and 0.003 s-1 for particles sizes of 4 nm, 7 nm and 11 nm, respectively. The results obtained indicated that small particles were more active in catalytic reduction due to their high surface energy.
本文以柠檬酸三钠为表面活性剂稳定剂,硼氢化钠为还原剂,在室温下合成了不同尺寸的金纳米颗粒。透射电子显微镜(TEM)证实,合成的样品呈球形,具有3种不同的粒径:4 nm、7 nm和11 nm。紫外可见光谱测量用于分析表面等离子体带受不同颗粒大小影响的方式。研究了球尺寸对4-硝基苯酚光催化还原反应的影响,计算了球尺寸为4 nm、7 nm和11 nm时的还原速率常数分别为0.014 s-1、0.0091 s-1和0.003 s-1。结果表明,小颗粒由于具有较高的表面能,在催化还原中表现出更强的活性。
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引用次数: 14
Effect of Titanium Dioxide Nano Particles Incorporation on Mechanical and Physical Properties on Two Different Types of Acrylic Resin Denture Base 纳米二氧化钛颗粒掺入对两种不同类型丙烯酸树脂义齿基托力学物理性能的影响
Pub Date : 2016-07-05 DOI: 10.4236/WJNSE.2016.63011
Mohamed Ahmed, M. El-Shennawy, Yousef M. Althomali, A. Omar
The aim of this study is to clarify the effect of different concentrations of titanium dioxide nanoparticles (Nps) on the properties of two types of heat polymerized acrylic resin. The tested parameters were flexural strength, impact strength, and microhardness. The two types of acrylic resin used in this study were conventional unmodified (Implacryl, Vertex) and high impact heat polymerized acrylic resin (Vertex-Dental, Netherlands). Both types of acrylic resin were modified by using 1% and 5% TiO2 Nps powder. Specimen’s dimensions were prepared according to the American Dental Association Specification No. 12. Three types of specimens were prepared: 1) flexural strength specimens 50 mm × 10 (±0.2) mm × 3 (±0.2) mm, 2) impact strength test specimens 60 mm × 6.0 mm × 4.0 mm, 3) microhardnesss specimens 25 mm × 10 mm × 3 (±0.2) mm. For each test 6 groups were prepared (each group containing 5 samples). Thirty specimens were prepared in each of the three tests, amounting to a total number of 90 specimens. Mechanical properties such as flexural strength (FS), impact strength and microhardness of the above mentioned specimens were determined using universal testing machine, Izod pendulum impact testing machine and Vickers microhardness tester, respectively. ISO Specification No. 1567 was followed in microhardness test. The data was collected and statistically analyzed. Flexural strength considerably decreased by increasing TiO2 concentration in both types of acrylic resin. Impact strength of the conventional acrylic resin modified by 1% of additives significantly increased. The microhardness is significantly increased by addition of 5% of TiO2 Nps. The Incorporation of TiO2 nanoparticles into acrylic resins can adversely affect its flexural strength. Meanwhile, the impact strength can be modified by small percentage of additives (abt. 1%). This effect is directly correlated with the concentration of nanoparticles. On the other hand, concentrations of TiO2 Nps (abt. 5%) positively affect the microhardness of both types of acrylic resin used in the present study.
本研究的目的是阐明不同浓度的二氧化钛纳米颗粒(Nps)对两种热聚合丙烯酸树脂性能的影响。测试参数为抗弯强度、冲击强度和显微硬度。本研究中使用的两种丙烯酸树脂是常规的未改性丙烯酸树脂(Implacryl, Vertex)和高冲击热聚合丙烯酸树脂(Vertex- dental,荷兰)。分别用1%和5%的TiO2 Nps粉末对两种丙烯酸树脂进行改性。样品的尺寸根据美国牙科协会规范第12号制备。制备三种试样:1)抗弯强度试样50 mm × 10(±0.2)mm × 3(±0.2)mm, 2)冲击强度试样60 mm × 6.0 mm × 4.0 mm, 3)显微硬度试样25 mm × 10 mm × 3(±0.2)mm,每组制备6组(每组5个试样)。三次试验各制备30个试样,共制备90个试样。采用万能试验机、伊佐德摆锤式冲击试验机和维氏显微硬度计分别测定上述试样的抗弯强度(FS)、冲击强度和显微硬度等力学性能。显微硬度试验按照ISO 1567规范进行。收集数据并进行统计分析。随着TiO2浓度的增加,两种类型的丙烯酸树脂的抗弯强度显著降低。常规丙烯酸树脂经1%的添加剂改性后,冲击强度明显提高。添加5%的TiO2 Nps可显著提高材料的显微硬度。二氧化钛纳米颗粒掺入丙烯酸树脂中会对丙烯酸树脂的抗弯强度产生不利影响。同时,加入少量的添加剂(约1%)也能提高材料的冲击强度。这种效应与纳米颗粒的浓度直接相关。另一方面,TiO2 Nps的浓度(约5%)正影响本研究中使用的两种丙烯酸树脂的显微硬度。
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引用次数: 69
Technology of Porous Tantalum Production 多孔钽生产技术
Pub Date : 2016-04-15 DOI: 10.4236/WJNSE.2016.62006
Y. Tuleushev, V. Volodin, Е. А. Zhakanbaev, V. Lisitsin, A. Migunova, A. Suleymenova
Ion-plasma sputtering and codeposition of ultrafine Ta and Cd particles on a moving substrate were used to prepare the solid solutions, in particular, the alloys with up to 66.2 at.% Cd in the form of coatings. In vacuum heat treatment cadmium evaporates at 700°C from cadmium based solid solutions resulting in formation of a porous tantalum with a highly developed surface. The prepared tantalum-based materials assume the technological application of the investigation results.
采用离子等离子溅射和超细Ta和Cd颗粒在移动衬底上共沉积的方法制备了固溶体,特别是制备了高达66.2 at的合金。% Cd以涂层的形式存在。在真空热处理中,镉在700°c时从镉基固溶体中蒸发,形成具有高度发达表面的多孔钽。制备的钽基材料承担了研究成果的技术应用。
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引用次数: 0
Electrospinning and Electrospun Nanofibers 静电纺丝和静电纺纳米纤维
Pub Date : 2016-04-15 DOI: 10.4236/WJNSE.2016.62005
Lefayet Sultan Lipol, M. Rahman
Electro-spinning is a very modern process which can be used in various purposes. We did this experimental work at Swerea IVF in Sweden during M. Sc in Textile Technology programme at University of Bor?s. We should especially thank our supervisor—Anna Thorvaldsson and course teacher—Ioannis S. Chronakis. In this report, we have tried to explain the basic manufacturing techniques of the electrospun nanofiber by the electro-spinning, how one can characterize it by SEM (Scanning Electron Microscopy) and its various applications in the practical field, e.g wound healing, Tissue Engineering Scaffold. The experimental work helped us a lot to gather sufficient knowledge about the electro-spinning process which we wanted to share with all.
电纺丝是一种非常现代的工艺,可用于各种用途。我们在瑞典博尔斯大学纺织技术硕士项目期间在斯韦厄试管婴儿中心进行了这项实验工作。我们要特别感谢我们的导师anna Thorvaldsson和课程老师ioannis S. Chronakis。本文介绍了电纺丝纳米纤维的基本制造技术、如何用扫描电子显微镜对其进行表征,以及电纺丝纳米纤维在伤口愈合、组织工程支架等实际领域的应用。实验工作帮助我们收集了足够的关于电纺丝过程的知识,我们想与大家分享。
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引用次数: 16
Fourth-Order Compact Formulation for the Resolution of Heat Transfer in Natural Convection of Water-Cu Nanofluid in a Square Cavity with a Sinusoidal Boundary Thermal Condition 具有正弦边界热条件的方形腔中水-铜纳米流体自然对流传热解析的四阶紧凑公式
Pub Date : 2016-04-15 DOI: 10.4236/WJNSE.2016.62009
M. Zaydan, Naoufal Yadil, Z. Boulahia, Abderrahim Wakif, R. Sehaqui
In the present work, we numerically study the laminar natural convection of a nanofluid confined in a square cavity. The vertical walls are assumed to be insulated, non-conducting, and impermeable to mass transfer. The horizontal walls are differentially heated, and the low is maintained at hot condition (sinusoidal) when the high one is cold. The objective of this work is to develop a new height accurate method for solving heat transfer equations. The new method is a Fourth Order Compact (F.O.C). This work aims to show the interest of the method and understand the effect of the presence of nanofluids in closed square systems on the natural convection mechanism. The numerical simulations are performed for Prandtl number ( ), the Rayleigh numbers varying between  and for different volume fractions varies between 0% and 10% for the nanofluid (water + Cu).
在本工作中,我们数值研究了纳米流体在方形腔内的层流自然对流。垂直壁假定是绝缘的,不导电的,不渗透的传质。水平壁被差分加热,当高壁冷时,低壁保持在热状态(正弦)。本工作的目的是建立一种新的高度精确的传热方程求解方法。该方法是一种四阶压缩(F.O.C)方法。这项工作旨在展示该方法的兴趣,并了解纳米流体在封闭方形系统中存在对自然对流机制的影响。对纳米流体(水+ Cu)的普朗特数()和不同体积分数的瑞利数(0% ~ 10%)进行了数值模拟。
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引用次数: 2
Processing and Characterization of PMMA Nanofiber Reinforced Epoxy Composites PMMA纳米纤维增强环氧复合材料的制备与表征
Pub Date : 2016-04-15 DOI: 10.4236/WJNSE.2016.62007
S. Al-Assafi, Nils de Bruijn, A. Al-Jumaily
Growing demand for high-performance materials is driving the development of composites with nano material reinforcement. The use of nano reinforcement can provide a distinct advantage due to high surface area of the material. There are still many challenges in achieving the full potential of nanocomposites. In this paper, we investigate the performance of epoxy nanocomposites reinforced with short polymethyl methacrylate (PMMA) nanofibers. PMMA nanofibers were chopped and mixed with the epoxy resin and then the mixture was poured into a mould. Samples were cut to an appropriate size after cure and mechanical testing was carried out. Tensile and flexural strength and modulus were evaluated for samples with various fiber volume fractions to determine changes in mechanical performance. Also Scanning Electron Microscopy was utilized to investigate fracture surface and fiber-matrix interface. Results indicated that mechanical performance dropped as volume fraction of fibers increased, namely poor fiber-matrix adhesion and presence of porosity resulted in deterioration in strength and modulus. Further research is required to develop fiber coating system to enhance performance of the nanocomposite by improving fiber-matrix adhesion and fiber wet-out.
对高性能材料日益增长的需求正在推动纳米材料增强复合材料的发展。由于材料的高表面积,使用纳米增强材料可以提供一个明显的优势。要充分发挥纳米复合材料的潜力,仍有许多挑战。本文研究了短聚甲基丙烯酸甲酯(PMMA)纳米纤维增强环氧纳米复合材料的性能。将PMMA纳米纤维切碎后与环氧树脂混合,然后倒入模具中。试样经固化后切至适当尺寸,进行力学试验。拉伸和弯曲强度和模量评估样品与不同的纤维体积分数,以确定机械性能的变化。同时利用扫描电镜对断口表面和纤维-基体界面进行了观察。结果表明,随着纤维体积分数的增加,材料的力学性能下降,即纤维与基体的粘附性差和孔隙率的存在导致材料的强度和模量下降。为了提高纳米复合材料的性能,需要进一步研究开发纤维涂层体系,以改善纤维与基体的粘附性和纤维的湿性。
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引用次数: 3
Effect of Nanoparticles Reinforced Adhesive Layers on Microleakage of Tooth Restorations 纳米颗粒增强粘接层对牙体微渗漏的影响
Pub Date : 2016-04-15 DOI: 10.4236/WJNSE.2016.62008
Mohamed I. Ebrahim, Mohamed Ahmed, Nayef H. Felemban
Adhesive layer is an essential part of tooth colored restorations which play an important role in decreasing the microleakage between the tooth and restoration material after polymerization shrinkage. The purpose of this study was to evaluate the effect of deferent adhesive system of bonding agent on microleakage of nanocomposite resin in class II cavities. Two different types of adhesive systems: universal adhesive (ExciTE) and a newly developed adhesive (Nano-Bond) and one type of light-cured resin restorative material (nanocomposite resin) were used in this study. These adhesives were applied to prepared tooth cavities by either manufactures’ instructions or by an experimental method (single or double application). Nanocomposite resin was then placed and light-cured for 40 seconds. Teeth were subjected to 500 thermal cycles between 5d microleakage was observed microscopically. The data were analyzed by a two-way ANOVA. For comparison between groups, Tukey’s post-hoc test was used. Nanoparticles reinforced adhesive system shows low microleakage in compare with universal adhesive system, and application of two adhesive layers also can decrease the microleakage. The ability of stress absorption by adhesive layer after polymerization shrinkage of restoration material will reduce the microleakage.
粘结层是牙体彩色修复体的重要组成部分,对减少聚合收缩后牙体与修复体材料之间的微渗漏起着重要的作用。本研究的目的是评价不同粘结体系的粘结剂对纳米复合树脂在II类腔体中微泄漏的影响。本研究使用了两种不同类型的胶粘剂:通用胶粘剂(ExciTE)和新开发的胶粘剂(Nano-Bond),以及一种光固化树脂修复材料(纳米复合树脂)。根据制造商的说明或实验方法(单次或双次应用)将这些粘合剂应用于准备好的牙腔。然后放置纳米复合树脂并光固化40秒。牙齿在5d内进行500次热循环,显微镜下观察微渗漏。数据采用双因素方差分析。组间比较采用Tukey’s事后检验。纳米粒子增强胶粘剂体系与普通胶粘剂体系相比具有较低的微漏率,两层胶粘剂的应用也能降低微漏率。修复材料聚合收缩后粘接层的应力吸收能力将减少微泄漏。
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引用次数: 2
Therapeutic Potential of Neem Synthesized Silver Nanoparticles on Human Gastric Cancer Cells in Vitro 印楝合成纳米银对人胃癌细胞的体外治疗潜力
Pub Date : 2016-04-15 DOI: 10.4236/WJNSE.2016.62010
T. A. Sironmani
Nanotechnology has shown significant promise in development of drugs and drug delivery systems that can overcome all limitations and address urgent needs to improve efficacy of diagnosis and therapy of various diseases including cancer. The functionalization with neem compounds as synthesis and capping agent had shown very high anticancer activities against Gastric cancer cells in vitro. The biochemical factors like albumin, glucose, and DNA concentrations were modulated along with Protease inhibitor and Catalase activates, the various cancer specific proteins like p53, GRD 70 - 78 kDa and other proteins of sizes 35 - 40 kDa corresponding to H+K+ATPase protein etc. The apoptic activity and antiproliferative activity were demonstrated with Gastric cancer cells in vitro.
纳米技术在开发药物和药物输送系统方面显示出巨大的希望,这些药物和药物输送系统可以克服所有限制,解决提高包括癌症在内的各种疾病的诊断和治疗效率的迫切需要。以楝树化合物为合成和封盖剂的功能化物在体外对胃癌细胞显示出很高的抗癌活性。随着蛋白酶抑制剂和过氧化氢酶的激活,各种癌症特异性蛋白如p53、GRD 70 - 78 kDa和其他大小为35 - 40 kDa的H+K+ atp酶蛋白等蛋白的激活,白蛋白、葡萄糖和DNA浓度等生化因子被调节。体外对胃癌细胞进行细胞凋亡活性和抗增殖活性研究。
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引用次数: 8
Effect of Ba Substitution on the Structural and Magnetic Properties of BiFeO 3 Ba取代对bifeo3结构和磁性能的影响
Pub Date : 2016-01-15 DOI: 10.4236/WJNSE.2016.61004
V. Srinivas, A. Raghavender, K. Kumar
Bi1-xBaxFeO3 (0 ≤ x ≤ 0.3) nanopowders were synthesized using sol-gel technique. The structural and magnetic properties were investigated using X-ray diffraction, SEM and VSM. As Ba2+ doping concentration was increased, the structure of the samples changed from rhombohedral to tetragonal or monoclinic. The structural change might be an important factor for achieving the ferroelectric properties in this material. The lattice parameters were observed to increase with increase in Ba2+ concentration. All the M-H loops showed the ferromagnetic behavior. Magnetization was observed to enhance with increase in Ba concentration. The enhancement in the magnetization due to Ba2+ doping may be due to the replacement of Bi3+ ions by Ba2+ which might have resulted in the suppression of spiral spin structure.
采用溶胶-凝胶法制备了Bi1-xBaxFeO3(0≤x≤0.3)纳米粉体。利用x射线衍射、扫描电镜和VSM对其结构和磁性能进行了表征。随着Ba2+掺杂浓度的增加,样品的结构由菱面体变为四方或单斜体。结构变化可能是实现该材料铁电性能的重要因素。晶格参数随Ba2+浓度的增加而增加。所有的M-H环都表现出铁磁性。磁化强度随Ba浓度的增加而增强。由于Ba2+掺杂导致的磁化强度增强可能是由于Ba2+取代了Bi3+离子,从而抑制了螺旋自旋结构。
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引用次数: 8
Sol-Gel Synthesis Using Novel Chelating Agent and Electrochemical Characterization of Binary Doped LiMn 2 O 4 Spinel as Cathode Material for Lithium Rechargeable Batteries 新型螯合剂的溶胶-凝胶合成及二元掺杂limn2o4尖晶石锂电池正极材料的电化学表征
Pub Date : 2016-01-15 DOI: 10.4236/WJNSE.2016.61001
R. Thirunakaran, Gil Hwan Lew, W. Yoon
LiMn2O4 and LiCuxCryMn2-x-yO4 (x = 0.50; y = 0.05 - 0.50) powders have been synthesized via sol-gel method for the first time using Myristic acid as chelating agent. The synthesized samples have been taken to physical and electrochemical characterization such as thermo gravimetric analysis (TG/DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and electrochemical characterization viz., electrochemical galvanostatic cycling studies, electrochemical impedance spectroscopy (EIS) and differential capacity curves (dQ/dE). XRD patterns of LiMn2O4 and LiCuxCryMn2-x-yO4 confirm high degree of crystallinity with good phase purity. FESEM image of undoped pristine spinel lucidly depicts cauliflower morphology with good agglomerated particle size of 50 nm while 0.5-Cu doped samples depict the pebbles morphology. TEM images of the spinel LiMn2O4 and LiCu0.5Cr0.05Mn1.45O4 authenticate that all the synthesized particles via sol-gel method are nano-sized (100 nm) with spherical surface and cloudy particles morphology. The LiMn2O4 samples calcined at 850℃ deliver the high discharge capacity of 130 mA·h/g with cathodic efficiency of 88% corresponds to 94% columbic efficiency in the first cycle. Among all four compositions studied, LiCu0.5Cr0.05Mn1.45O4 delivers 124 mA·h/g during the first cycle and shows stable performance with a low capacity fade of 1.1 mA·h/g cycle over the investigated 10 cycles.
LiMn2O4和LiCuxCryMn2-x-yO4 (x = 0.50;以肉豆蔻酸为螯合剂,首次采用溶胶-凝胶法制备了y = 0.05 ~ 0.50)粉末。对合成的样品进行了热重分析(TG/DTA)、x射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、场发射扫描电镜(FESEM)、透射电镜(TEM)等物理和电化学表征,即电化学恒流循环研究、电化学阻抗谱(EIS)和差分容量曲线(dQ/dE)。LiMn2O4和LiCuxCryMn2-x-yO4的XRD谱图证实结晶度高,相纯度好。未掺杂的原始尖晶石的FESEM图像清晰地描绘了花椰菜的形态,具有良好的团聚粒度为50 nm,而掺杂0.5 cu的样品则描绘了鹅卵石的形态。尖晶石LiMn2O4和LiCu0.5Cr0.05Mn1.45O4的TEM图像验证了溶胶-凝胶法合成的颗粒均为纳米级(100 nm),表面呈球形,颗粒形态呈浑浊状。850℃煅烧后的LiMn2O4样品放电容量高达130 mA·h/g,阴极效率达到88%,第一次循环的哥伦比亚效率达到94%。在所研究的四种成分中,LiCu0.5Cr0.05Mn1.45O4在第一次循环时输出124 mA·h/g,并且在10次循环中表现出较低的容量衰减,仅为1.1 mA·h/g。
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引用次数: 6
期刊
纳米科学与工程(英文)
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