X射线能谱研究鞣性金属在绵羊皮革中的分布

以绵羊皮革为研究对象,利用X射线能谱仪(EDXA)分析了鞣性金属锆铬在绵羊皮革中的分布,结果表明:鞣性金属元素锆、铬在绵羊皮革中的分布整体上比较均匀,但局部存在不均匀现象,鞣性金属组分主要分布于纤维束边缘,纤维束的空隙和内部含量均较低.     

基于Bayesian估计和Wiener滤波的阈值去噪方法

基于阈值的小波域去噪方法的核心是阈值选取,通过最小化一个Bayesian风险函数得到一种自适应阈值,结合线性滤波中具有代表性的Wiener方法,提出了一种新的去噪方法.实验结果表明,该方法能有效地去除图像中的白噪声,同时还能较好地保留图像的边缘信息,其效果优于目前的一些小波阈值去噪方法.     

声波振动在聚合物加工中作用的研究进展

声波在聚合物加工中的应用的研究越来越得到重视。本文综述了声波在聚合物加工中的应用的研究进展情况。     

皮革产品的ATR-FTIR快速鉴定

分析和比较真皮和人造革的 ATR- FTIR红外谱图表明 ,两者的特征峰峰位并不重叠或干扰 ,其结构可以区分。用 ATR- FTIR鉴定皮革产品具有准确、灵敏、快速、简便、对产品无损伤、无需预处理、易实现现场自动化等优点     

A new method of ultrasound color flow mapping

Conventional ultrasound color flow mapping systems estimate and visualize only the axial velocity component. To obtain the transverse velocity component a modification of a multiple-beam method is proposed. The new two-dimensional color flow mapping system has a small size and consists of three transducers. The central transducer is an appodized and focused phased array. The other transducers are unfocused probes. Three transducers act as receivers and the central transducer operates as a transmitter. All receivers acquire rf scan lines that are then processed to estimate three axial velocity components using an autocorrelation method. These estimates are then combined to estimate the transverse velocity component, taking into account the geometric relationships among three transducers. Two algorithms for transverse velocity estimation are proposed. The first uses the Doppler angle estimate for calculation of the transverse velocity component. The other algorithm calculates the transverse velocity component directly from the axial components. The accuracy of the flow velocity estimators is estimated by simulations. Analysis of accuracy allows choosing the more effective algorithm for two-dimensional velocity estimation, which is insensitive to variations of the Doppler angle.     

A preliminary in vitro assessment of polymer-shelled microbubbles in contrast-enhanced ultrasound imaging

This paper focuses on the use of poly (vinyl alcohol)-shelled microbubbles as a contrast agent in ultrasound medical imaging. The objective was an in vitro assessment of the different working conditions and signal processing methods for the visual detection (especially in small vessels) of such microbubbles, while avoiding their destruction. Polymer-shelled microbubbles have recently been proposed as ultrasound contrast agents with some important advantages. The major drawback is a shell that is less elastic than that of the traditional lipidic microbubbles. Weaker echoes are expected, and their detection at low concentrations may be critical. In vitro experiments were performed with a commercial ultrasound scanner equipped with a dedicated acquisition board. A concentration of 100 bubbles/mm³, excitation pressure amplitudes from 120 kPa to 320 kPa, and a central frequency of 3 MHz or 4.5 MHz were used. Three multi-pulse techniques (i.e., pulse inversion, contrast pulse sequence based on three transmitted signals, and contrast pulse sequence in combination with the chirp pulse) were compared. The results confirmed that these microbubbles produce a weaker ultrasound response than lipidic bubbles with a reduced second-order nonlinear component. Nevertheless, these microbubbles can be detected by the contrast pulse sequence technique, especially when the chirp pulse is adopted. The best value of the contrast-to-tissue ratio was obtained at an excitation pressure amplitude of 230 kPa: although this pressure amplitude is higher than what is typically used for lipidic microbubbles, it does not cause the rupture of the polymeric contrast agent.     

A comparative analysis of multi-pulse techniques in contrast-enhanced ultrasound medical imaging

One of the important issues in the field of ultrasound medical imaging using contrast agents is the development of techniques able to separate the response of the contrast media from that of the biological tissues. In the literature, one can find various solutions involving the use of multiple transmitted signals and the combination of related echoes. However, the quality of these techniques may be reduced due to some undesired effects that are seldom considered, despite the fact that they are always present in real systems. These effects are the signal distortions introduced by the hardware equipment, the thermal noise in the electronic circuitry, and body motion between successive pulses. In this paper we propose a simulation tool that will allow the calculation of the backscattered echo from a population of contrast agents immersed in a biological tissue, considering all the mentioned effects. With this tool, an assessment of the comparative robustness of three well-known multi-pulse techniques has been carried out under realistic working conditions and the performance of the three techniques has been evaluated in terms of contrast-to-tissue ratio and signal-to-noise ratio. The results show that the undesired effects have a strong impact on these techniques and that there are notable differences in their robustness. Finally, some suggestions on the choice of the particular technique to be applied are provided on the basis of the specific work conditions.     

Design parameters for the separation of fat from natural whole milk in an ultrasonic litre-scale vessel

The separation of milk fat from natural whole milk has been achieved by applying ultrasonic standing waves (1 MHz and/or 2 MHz) in a litre-scale (5 L capacity) batch system. Various design parameters were tested such as power input level, process time, specific energy, transducer–reflector distance and the use of single and dual transducer set-ups. It was found that the efficacy of the treatment depended on the specific energy density input into the system. In this case, a plateau in fat concentration of ∼20% w/v was achieved in the creamed top layer after applying a minimum specific energy of 200 kJ/kg. In addition, the fat separation was enhanced by reducing the transducer reflector distance in the vessel, operating two transducers in a parallel set-up, or by increasing the duration of insonation, resulting in skimmed milk with a fat concentration as low as 1.7% (w/v) using raw milk after 20 min insonation. Dual mode operation with both transducers in parallel as close as 30 mm apart resulted in the fastest creaming and skimming in this study at ∼1.6 g fat/min.     

超声波在食品技术中的应用

强超声在媒质中传播时产生力学效应、空化效应和热效应,产匝此增强质量传输和热传递,对介质产生强的切向力。本文对超声波在辅助或强化提取,冷冻、乳化、结晶和干燥等食品的加工技术中应用加以综述。     

傅里叶变换衰减全反射红外光谱法鉴定皮革产品

ATR-FTIR(傅里叶变换衰减全反射红外光谱法)技术分析皮革材料的结构,依据不同物质所得ATR谱的不同,从而快速、简便地分析出真皮革和人造革。该实验技术对样品具有非破坏性,能够准确地对皮革样品进行鉴定。     

Application of ultrasound in preparing pathological sections to reduce processing time

It has been found experimentally that application of sub-mega and low megahertz ultrasound (US) of spatial and temporal averaged intensity I_sata up to 10 W/cm² during the process of preparing pathological sections of the mouse tissue has shortened the processing time from 12 h (without US) to less than half an hour (with US). The experiment has also showed that the processing time reached the shortest for ultrasound f = 200 kHz among the frequencies of 200 kHz, 400 kHz, 600 kHz, 800 kHz and 1 MHz used in this study. It has been proposed that ultrasound inducing non-inertial cavitation enhanced the permeability of cell membrane to liquid. Thus tissue fixation and dehydration were speeded up by application of US.     

一种皮革产品的红外无损检验

基于红外光谱法可以对不同形态物质进行结构分析,可对皮革产品进行定性分析。依据红外光谱谱带的数目、位置、形状和强度都随化合物不同而各不相同的特点,将牛皮革、羊皮革和聚氯乙烯（PVC）革的红外谱图进行比对和剖析,并用于皮革产品的检验。通过实验得出,利用红外方法可以快速对皮革产品进行红外无损检验。     

Ultrasound assisted enhancement in natural dye extraction from beetroot for industrial applications and natural dyeing of leather

There is a growing demand for eco-friendly/non-toxic colorants, specifically for health sensitive applications such as coloration of food and dyeing of child textile/leather garments. Recently, dyes derived from natural sources for these applications have emerged as an important alternative to potentially harmful synthetic dyes and pose need for suitable effective extraction methodologies. The present paper focus on the influence of process parameters for ultrasound assisted leaching of coloring matter from plant materials. In the present work, extraction of natural dye from beetroot using ultrasound has been studied and compared with static/magnetic stirring as a control process at 45 °C. The influence of process parameters on the extraction efficiency such as ultrasonic output power, time, pulse mode, effect of solvent system and amount of beetroot has been studied. The use of ultrasound is found to have significant improvement in the extraction efficiency of colorant obtained from beetroot. Based on the experiments it has been found that a mixture of 1:1 ethanol–water with 80 W ultrasonic power for 3 h contact time provided better yield and extraction efficiency. Pulse mode operation may be useful in reducing electrical energy consumption in the extraction process. The effect of the amount of beetroot used in relation to extraction efficiency has also been studied. Two-stage extraction has been studied and found to be beneficial for improving the yield for higher amounts of beetroot. Significant 8% enhancement in % yield of colorant has been achieved with ultrasound, 80 W as compared to MS process both using 1:1 ethanol–water. The coloring ability of extracted beet dye has been tested on substrates such as leather and paper and found to be suitable for dyeing. Ultrasound is also found to be beneficial in natural dyeing of leather with improved rate of exhaustion. Both the dyed substrates have better color values for ultrasonic beet extract as inferred from reflectance measurement. Therefore, the present study clearly offers efficient extraction methodology from natural dye resources such as beetroot with ultrasound even dispensing with external heating. Thereby, also making eco-friendly non-toxic dyeing of fibrous substances a potential viable option.     

皮革中甲醛含量测量不确定度评估

依据GB/T 19941-2005标准,测定了皮革中的甲醛含量,对测量结果的不确定度来源进行了分析和评定,并计算出合成不确定度和有效自由度,最后根据JJF1059规范要求给出了甲醛测量不确定度表达式.     

原子吸收光谱法测定饲料中铬和锌

采用WFX-1F2B2原子吸收分光光度计测定饲料中铬和锌,本方法通过选取用窄的光谱通带来减少复杂谱线的干扰;选用的富燃料还原火焰来抑制难熔氧化物的形成,提高检测的灵敏度.同时采用加入1%硫酸钠溶液及1%柠檬酸溶液的方法来消除Fe、Ca、Cu、Mg、Mn、Si等元素对铬的干扰;加入0.1%镧盐溶液来消除其对锌的干扰,而采用标准加入法的测定方式又消除了饲料基体中其他未知因素的影响,此法同时测定了饲料中的铬、锌的含量,快速、简便、准确性高、重现性好,获得了满意的效果.