共查询到19条相似文献,搜索用时 468 毫秒
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设计并搭建了超声光栅,观察了激光经过光栅形成的衍射斑纹,测量了声速;并利用超声光栅测定了不同温度、不同浓度的NaCl溶液中的声速,给出了声速-水温和声速-溶液浓度的依赖关系.水的温度每升高1℃,3.974 MHz的超声波的声速增加2.09 m/s,16.574 MHz的超声波的波速增加2.04m/s;声速随着NaCl溶液浓度的增大线性增加,NaCl溶液浓度每升高1%,3.974 MHz的超声波声速增加13.637 m/s,16.574 MHz的声波声速增加11.757 m/s.在此基础上,分析了不同频率的超声波对实验规律的影响,认为不同频率的超声波在相同条件下测量的溶液中声速大小的不同源于测量的随机误差. 相似文献
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利用紫外-可见(Uv-Vis)光谱和荧光光谱研究了超声波照射激活纳米二氧化硅(SiO2)粒子对牛血清白蛋白(BSA)分子的损伤,并考查了超声波照射时间、纳米SiO2粉末加入量、溶液酸度和超声波照射功率等因素对BSA分子损伤程度的影响.结果表明,对于体系温度为(37.0±0.2)℃和浓度为1.0×10-5mol·-1的BSA溶液,UV-Vis光谱显示,随着超声波照射时间,纳米SiO2粉末加入量,溶液pH值和照射功率的增大呈现出越来越明显的增色效应.然而,BSA溶液的荧光光谱却随着上述因素的增大呈现出越来越明显的猝灭现象.此外,还初步探讨了超声波照射激活纳米siO2粒子对BSA分子损伤的机理,认为是声致发光或高热激发使纳米siO2粒子产生·OH自由基,进而损伤溶液中的BSA分子.这一研究结果对声催化方法应用于临床治疗肿瘤以及纳米药物的开发具有一定的指导意义. 相似文献
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根据声光效应原理,利用分光计和超声光栅对生活中几种常见液体(蒸馏水、75%乙醇、食用油、5%Na Cl溶液、30%葡萄糖溶液)中的声速进行了测量,同时测量了不同浓度葡萄糖溶液中的超声波声速,并利用Origin软件对其进行数据拟合分析,结果显示:不同液体介质和同种液体不同浓度对超声波声速的测量均有一定程度的影响。在几种常见的液体中,葡萄糖溶液中测量的声速误差最小;超声波在葡萄糖溶液中传播的速度在一定浓度范围内线性增大,而在浓度为32%葡萄糖溶液中的声速的拟合残差最小,该浓度下测量的超声波声速精确度最高,可作为测量超声波在葡萄糖溶液中传播速度的有效浓度。 相似文献
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利用流变仪研究了甲基纤维素(MC)溶液在NaCl、十六烷基三甲基溴化铵(HTAB)以及两者共存下MC溶液的凝胶化行为,发现其凝胶化温度随着NaCl浓度的增加而下降,随着HTAB浓度的增加而上升;但是MC/NaCl的凝胶化温度保持不变,与HTAB浓度
无关,而MC/HTAB溶液的凝胶化温度则随着NaCl浓度的增加而下降.以上的实验结果表明,在NaCl存在下,HTAB将被诱导形成胶束,因此MC/NaCl的凝胶化温度保持不变;反之,当NaCl不存在时,HTAB将优先吸附到MC上而不会在溶液中形成胶束,尽管其浓度 相似文献
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采用不同电功率的超声波处理了聚乙二醇(PEG6000)溶液。凝胶渗透色谱(GPC)分析超声处理后的PEG溶液发现,当超声电功率超过250W时,PEG分子量随超声波作用强度的增大而减少,随超声波作用时间的延长而增大;在电功率超过250W超声波作用下,傅立叶红外光谱(FT-IR)分析表明,组成PEG的单体没有明显改变,但是,羟基含量分析表明,PEG固体样品中的羟基含量有所减少。结合实验结果,根据高分子化学、有机化学和超声化学中相关理论对PEG超声化学反应机理进行了探讨,认为:当超声波作用于PEG溶液时,同时存在有PEG的缩水聚合反应和自由基降解反应,当频率为20-25kHz、电功率为250-600W的超声作用于PEG6000溶液时,缩水聚合反应占主导地位。 相似文献
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I.InstrumentUltrasonichydroch1oricacidconcentrationmeter(Fig.l)measureson-linetheconccntra-honofhydroch1oricacidsolutioninwhichtheultrasonicve1ocitychangeswiththevariationoftheconcentrationandtemperatureoftheso1ution[1].Theconcentrationofhydrochloricacidso1utiotiwithdifferentconcentrationcanbegiven[']asD=ffc,T,P)(l)wherecistheu1trasonicvc1ocityinhydroch1oricacidsolution,Tisthctemperatilreofhydrochloricacidso1utionandPisthepressureofhydroch1oricacidsolution.Whenthcprcs-surePisaconstanLtheco… 相似文献
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Measuring ultrasonic velocity is an efficient means of determining electrode quality for electric arc furnaces. Close correlation between ultrasonic velocity and the physico-mechanical characteristics of the electrodes was obtained by statistical analysis.The variation of ultrasonic velocity is shown for different fabrication stages of graphite electrodes as a function of their mechanical characteristics and structure. We also present some aspects of the experimental work and apparatus used. 相似文献
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J. Jayaraju K. C. Basavaraju S. K. Rai 《Journal of Macromolecular Science: Physics》2013,52(5):741-751
Measurements of viscosity, ultrasonic velocity, refractive index, and density of chitosan (CS)/polyethylene glycol (PEG) blends in buffer solution (0.1 M acetic acid+0.2 M sodium acetate) were carried out for different blend compositions at 30, 40, and 50°C. Using the viscosity data, interaction parameters μ and α were computed to determine miscibility. These values revealed that the blend was miscible when the chitosan content was more than 60% of the blend. The results were further confirmed by ultrasonic velocity, density, and refractive index measurements. Further, the results revealed that the change in temperature has no significant effect on the miscibility of CS/PEG polymer blends. 相似文献
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除垢超声波传播影响因素的理论研究 总被引:1,自引:0,他引:1
从一维平面波理论入手分析了超声波声压分布特性。依据多普勒频移原理,在声场的运动方程,连续性方程,波动方程的基础上,建立一个超声波在流动的液体中传播的控制方程。根据轴对称模型的实际特点,简化了所得方程,并求出解析解。结果表明流动液体可以产生声波的衰减。液体的黏滞性是产生超声波衰减的重要原因。超声波的频率较高,液体的黏滞性对超声波衰减影响明显。依据黏滞力与速度梯度的关系,建立一个超声波在黏滞液体传播的控制方程,并依据边界条件求出解析解,反映了媒质黏滞性对超声波传播尤其是衰减特性的影响。 相似文献
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J. Jayaraju S. K. Rai Shetty Ravindra Rama 《Journal of Macromolecular Science: Physics》2013,52(2):296-304
Polymer blends of chitosan (CHI) with poly(vinyl pyrrolidone) (PVP) have been prepared by solution blending, and their miscibility studies were carried out by using physical techniques over an extended range of concentration and composition in buffer solution. The viscosity, ultrasonic velocity, density, and refractive index were measured at 30, 40, and 50°C, respectively. Using viscosity data, the interaction parameter μ and α were computed to probe the miscibility. These values revealed that the blend is miscible when the chitosan content is more than 60% in the blend at all temperatures. The obtained results were further confirmed by the ultrasonic velocity, density, and refractive index measurements. 相似文献
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Magnesium alloy is one of the most promising biomaterials in vascular clogging and bone injury. But it still has some defects to overcome and the key task is to control the degradation velocity. In this study, the reaction between NaCl solution and MgO is simplified as the first stage of the degradation of magnesium alloy stent, and the adsorption properties of NaCl solution on the MgO surface are investigated by MD simulation. The distribution of each component of the solution perpendicular to the MgO surface is analysed and the diffusion coefficient is calculated. Besides, a parameterised analysis is carried out. The results show that there is a solution layer formed at the surface of the MgO, and the existence of metal oxide restricts the diffusion of the solution. The adsorption capacity and the diffuse rate have an opposite variation tendency with the change of temperature, concentration and velocity. The self-diffusion coefficient of the solution increases with the increase in temperature as well as velocity, inversely adsorption capacity decreases with the increase in velocity. Besides, the influence of temperature on the adsorption capacity is small. What is more, the diffusion coefficient decreases while the adsorption capacity increases with the increase in concentration. 相似文献
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为了提高超声波测距精度,构建了基于AVR单片机的测距及数据处理系统。分析了超声波测距的原理,以AVR单片机为处理器设计了超声波产生和发射电路、超声波接收和信号处理电路以及温度测量和补偿电路等。针对温度对超声波速度的影响,根据超声波速度与温度的关系,设计了超声波速度补偿算法。为了提高回波时间测量准确性,减小随机噪声及空气中其他杂散播干扰的影响,采用均值数字滤波方法,对计数时间进行处理。实测结果表明,在3cm~400cm范围内,超声波测距系统测量数据准确,最大误差为0.66cm。 相似文献