EDXRF测定土壤元素含量及其在有机碳垂直分布特征研究中的应用

针对X射线荧光光谱(XRF)法不确定度计算和测定地质样品中硫的准确度、精密度与可靠性不高的难点,研究了提高土壤中硫分析准确度的途径,建立了土壤中S的XRF分析方法,完善了偏振能量色散XRF测定土壤中主、次、痕量元素的方法,利用不确定度评价、证实了所见方法的有效性和可靠性。测定、获得了研究区土壤元素剖面,通过对短期植被更替土壤剖面的土壤有机碳含量(TOC)、有机碳稳定碳同位素((13C)特征及其与元素垂直分布的关系研究,发现土壤中元素含量与有机碳含量和有机碳稳定碳同位素存在显著相关性。     

硅中掺杂元素砷的三维微分析

利用同步辐射Ｘ光微区分析和全反射Ｘ射线荧光分析技术测定了硅中掺杂元素砷浓度的三维分布，其中深度剖面分布的测定结果与二次离子质谱进行了对照，两的一致性是比较满意的。     

Ta2O5/Ta界面分析的新模型

对Ta₂O₅/Ta样品界面区的深度剖面曲线进行了研究。基于离子溅射引起影响层存在的考虑,提出一种解释该曲线的新模型。通过此模型能很好地拟合实验曲线,并反映了溅射过程中的离子混合效应、原子堆积效应及相应的特征参数。样品由阳极氧化法制得,其厚度为500埃。表面分析在PHI-590型扫描俄歇微探针上完成,所有测量均在室温下进行。研究表明:深度剖面曲线并不符合误差函数分布;影响层的厚度为30—50埃,它是进行深度剖面分析时,决定元素俄歇信号强度的第一位重要因素;深度剖面 关键词：     

微束X射线荧光光谱分析红土中铁锰结核内部微小区域

在中国南方第四纪红土剖面中普遍发育一种黑褐色,形状规则或者不规则的新生体,由于其含有较高的Fe和Mn元素而被称为铁锰结核。铁锰结核被认为是土壤中温度、水分、氧化还原条件变化而形成的土壤新生体,因此它被认为是环境信息的良好载体。尤其是结核内部发育的环带状构造,被认识是结核形成过程气候干湿变化的结果。因此对结核内部微小区域的研究,有助与理解红土母质的风化过程以及结核的形成原因。X射线荧光光谱分析在20世纪80年代初已是一种成熟的分析方法,是实验室、现场分析主、次量和痕量元素的首选方法之一。运用帕纳科Zetium X射线荧光光谱仪的微小区域分析工具对铜陵第四纪红土中结核内部由核心至边缘的主量元素分布状况进行分析,结果表明,XRF微小区域分析功能可以快速有效的分析样品内元素的分布状况。结核内部元素分布情况来看,铜陵剖面内铁锰结核内部颜色深浅变化主要是由于Mn元素含量的变化而引起的。结核的核心Mn元素含量最高,由核心向边缘呈现高低交替变化特征。指示结核形成初期,由于气候相对干旱,Mn元素由低价离子态氧化成高价化合物后发生淀积。结核内部浅色环带Si和Al元素含量明显较深色环带高,可能代表了相对湿润的气候时期。     

ICP-MS在土壤元素污染评价中的应用

以云浮黄铁矿矿石作原料的某硫酸厂堆渣场土壤剖面为研究对象, 应用ICP-MS同时测定了污染元素和部分参考元素的含量,快速找出各元素的相关性,用富集因子评价了土壤的污染状态,并指出了污染元素的背景选择问题。结果表明：V已呈显著及高度污染,Co呈中度污染,并有显著污染的倾向,Cr, Mo和Cd在轻度和中度污染之间,Zn和Sb呈轻度污染,并有中度污染的潜在危险,Cu呈轻度污染。富集的高位点V和Cr在土壤剖面的上部(4.0～10. 5 cm)和深部(44.0～75. 5 cm),Co和Mo集中在土壤剖面表面(0～5.0 cm)、中上部(9.5～10.5 cm)和中部(29.5～46.0 cm),Cd和Cu集中在土壤剖面中部(29.5～46.0 cm)。高富集点的污染来自于以花岗岩为母质的亚热带强风化红壤的残余金属离子的淋溶淀积和堆渣场废渣中释放的金属元素在土壤中的迁移累积相互叠加的结果。其中V污染主要为土壤母质贡献,其次是硫酸生产过程失活催化剂挥发引入废渣的V淋溶淀积。     

微束X射线荧光光谱分析红土中铁锰结核内部微小区域（英文）

在中国南方第四纪红土剖面中普遍发育一种黑褐色,形状规则或者不规则的新生体,由于其含有较高的Fe和Mn元素而被称为铁锰结核。铁锰结核被认为是土壤中温度、水分、氧化还原条件变化而形成的土壤新生体,因此它被认为是环境信息的良好载体。尤其是结核内部发育的环带状构造,被认识是结核形成过程气候干湿变化的结果。因此对结核内部微小区域的研究,有助与理解红土母质的风化过程以及结核的形成原因。X射线荧光光谱分析在20世纪80年代初已是一种成熟的分析方法,是实验室、现场分析主、次量和痕量元素的首选方法之一。运用帕纳科Zetium X射线荧光光谱仪的微小区域分析工具对铜陵第四纪红土中结核内部由核心至边缘的主量元素分布状况进行分析,结果表明,XRF微小区域分析功能可以快速有效的分析样品内元素的分布状况。结核内部元素分布情况来看,铜陵剖面内铁锰结核内部颜色深浅变化主要是由于Mn元素含量的变化而引起的。结核的核心Mn元素含量最高,由核心向边缘呈现高低交替变化特征。指示结核形成初期,由于气候相对干旱,Mn元素由低价离子态氧化成高价化合物后发生淀积。结核内部浅色环带Si和Al元素含量明显较深色环带高,可能代表了相对湿润的气候时期。     

离子束流剖面分布离线诊断方法探索

提出了一种基于二次离子质谱分析技术的离子束流剖面分布的离线诊断方法,具有分辨率高、可同时给出束流剖面分布和成分信息的特点。利用数值模拟方法对该诊断方法的可行性进行了分析和讨论,并结合原理实验给出了验证结果。结果表明:该方法可以用于真空密封型中子发生器离子束流剖面分布的诊断,能够成为其他诊断方法的验证手段和有力补充。     

ICP-OES研究罗布泊“大耳朵”湖相沉积物常量元素地球化学特征及环境意义

光谱分析技术应用于地球化学元素分析研究,为湖泊沉积物反演环境变化提供了更多的环境信息。以罗布泊“大耳朵”区域L07-10剖面沉积物为研究对象,利用ICP-OES对常量地球化学元素进行了测定分析,结合AMS进行14C年代学测定,初步探讨了该地区16.34 ka BP以来的气候环境变化。结果表明：常量元素地球化学特征可以灵敏的指示环境变化,元素环境代用指标很好的反映了该地区的气候变化过程。总体来看, 常量元素分布特征指示16.34 ka BP以来,罗布泊区域气候经历了暖湿-暖干-凉湿-暖干的变化,在8.09～6.34 ka BP期间发生了一次较明显的短期升温阶段,这一时期气候温暖干燥,降水减少,与全球及区域气候变化相关记录相吻合。近2 000 a以来气候总体温暖,降水量减少,源区水热条件变差,水运的搬运能力降低。     

原子吸收光谱法测定乌骨羊肉中微量元素的研究

采用原子吸收光谱法测定乌骨羊肉的Fe,Cu和Zn的含量。该方法的加标回收率为98%—102%。结果表明：在乌骨羊肉中普遍存在Fe的含量大于Zn的含量,Zn的含量大于Cu的含量。其中Fe元素在肝脏中的含量最高,其次为心脏和肾脏;Zn元素在心脏中的含量最高,其次为颈肉;Cu元素在肝脏中的含量最高,其次为心脏。     

基于FTIR,ICP-MS的仿生Mg-Ag-HA/明胶抗菌生物涂层的制备与表征

目前,傅里叶变换红外光谱（FTIR）技术具有待测样品数量少、对特征基团灵敏度高、样品制备和分析简单等优点;电感耦合等离子体质谱（ICP-MS）的优势也较为显著：微量元素的高灵敏度检出率,低检测限和多元素的同时分析;协同上述两种方法,可快速对功能医用材料的化学元素和基团进行鉴定,从而为仿生医用抗菌材料的研发提供新的设计思路和理论依据。羟基磷灰石(HA)因其优异的骨传导和骨诱导特性被用于薄膜材料,钛植入表面HA薄膜已进入临床应用阶段。但是,HA的本真脆性和缺乏抗菌性,常常导致植入失败。因此,开发一种耐磨性好且抑菌性优的促成骨功能涂层成为当前急需要解决的难题。研究目的在于在钛表面制备耐磨性好且抑菌性优的促成骨功能涂层,初步探讨了涂层的抗菌离子缓释规律和生物活性。开拓性地在工业纯钛表面制备了明胶、银和镁离子改性的羟基磷灰石(Mg-Ag-HA/明胶)抗菌涂层。将银(Ag)引入羟基磷灰石涂层(HA)以改善其抗菌性能,镁(Mg)作为第二元素以提高生物相容性,明胶可以同时提高HA的生物相容性和力学性能。ICP-MS测定涂层中镁和银元素的释放量和可持续性。所得到的新型Mg-Ag-HA/明胶的SEM结果、Ca/P比值、化学特征峰和晶相通过FTIR, SEM,EDAX和XRD进行表征。结果表明：明胶的羧基与HA的钙离子之间已形成Ca-COO化学键,明胶和Mg-Ag-HA构成了有机-无机复合涂层;Mg和Ag元素被成功地引入到了HA晶格中,且分布均匀。模拟体液浸泡后,Mg-Ag-HA/明胶涂层试样表面有新的缺钙型的HA生成,且球形磷灰石中检测到新的Mg,Na和Cl元素;结果表明,新型复合涂层样品具有良好的生物活性。SEM和LSCM实验结果观察发现,小鼠颅骨成骨细胞在Mg-Ag-HA/明胶上粘附良好,细胞伸展大量伪足,未见细胞毒性。明胶的加入大大降低了复合镀层中Mg2+和Ag+的释放速率,提高了复合镀层的生理稳定性,为镀层保持长期抗菌功能提供了保证。Mg-Ag-HA/明胶作为钛基涂层材料具有良好的抗菌离子释放能力和优异的生物相容性,为新型抗感染外科植入体的研发提供了新思路。     

Application of Biot's theory to ultrasonic characterization of human cancellous bones: determination of structural, material, and mechanical properties

This paper is devoted to the experimental determination of distinctive macroscopic structural (porosity, tortuosity, and permeability) and mechanical (Biot-Willis elastic constants) properties of human trabecular bones. Then, the obtained data may serve as input parameters for modeling wave propagation in cancellous bones using Biot's theory. The goal of the study was to obtain experimentally those characteristics for statistically representative group of human bones (35 specimens) obtained from a single skeletal site (proximal femur). The structural parameters were determined using techniques devoted to the characterization of porous materials: electrical spectroscopy, water permeametry, and microcomputer tomography. The macroscopic mechanical properties, Biot-Willis elastic constants, were derived based on the theoretical consideration of Biot's theory, micromechanical statistical models, and experimental results of ultrasonic studies for unsaturated cancellous bones. Our results concerning structural parameters are consistent with the data presented by the other authors, while macroscopic mechanical properties measured within our studies are situated between the other published data. The discrepancies are mainly attributed to different mechanical properties of the skeleton frame, due to strong structural anisotropy varying from site to site. The results enlighten the difficulty to use Biot's theory for modeling wave propagation in cancellous bone, implying necessity of individual evaluation of input parameters.     

Group velocity, phase velocity, and dispersion in human calcaneus in vivo

Commercial bone sonometers measure broadband ultrasonic attenuation and/or speed of sound (SOS) in order to assess bone status. Phase velocity, which is usually measured in frequency domain, is a fundamental material property of bone that is related to SOS, which is usually measured in time domain. Four previous in vitro studies indicate that phase velocity in human cancellous bone decreases with frequency (i.e., negative dispersion). In order to investigate frequency-dependent phase velocity in vivo, through-transmission measurements were performed in 73 women using a GE Lunar Achilles Insight commercial bone sonometer. Average phase velocity at 500 kHz was 1489 +/- 55 m/s (mean +/- standard deviation). Average dispersion rate was -59 +/- 52 m/sMHz. Group velocity was usually lower than phase velocity, as is expected for negatively dispersive media. Using a stratified model to represent cancellous bone, the reductions in phase velocity and dispersion rate in vivo as opposed to in vitro can be explained by (1) the presence of marrow instead of water as a fluid filler, and (2) the decreased porosity of bones of living (compared with deceased) subjects.     

Ultrasonic non-destructive measurements of cortical bone thickness in human cadaver femur

The knowledge of the cortical bone thickness profile in human bone has a two-fold clinical significance: to study the stress occurring in a loaded bone structure to optimize the design of prostheses; and to predict the onset of advanced bone disease such as osteoporosis. In this study, the cortical bone thickness in three embalmed human cadaver femora were measured non-destructively using an ultrasonic technique. These thickness measurements were also made using a computed tomographic (CT) scanning method. Subsequently bones were sectioned and the actual bone thicknesses in the same regions were measured using a micrometer. The correlation coefficient between the actual thickness and the ultrasonically measured thickness was 0.95 and with the CT was 0.62. Thus, these results show that, under present experimental conditions, ultrasonic thickness measurements compare well with the micrometer actual thickness results. This technique, when fully developed, can be used as a non-destructive tool for quantitative cortical bone thickness measurements. Moreover, the ultrasonic technique does not use ionizing radiation.     

Effects of draining cochlear fluids on stapes displacement in human middle-ear models.

Displacement-frequency characteristics of the stapes footplate were measured in five human temporal bones before and after draining the vestibule. Measurements were made in the 0.125-8 kHz range at 80 dB input sound pressure level, using a laser Doppler vibrometer. A circuit model was also used to predict stapes displacement. The temporal bone studies show a slight decrease in stapes footplate displacement at low frequency, and little change above 1 kHz. The displacement change is not as great as that found by other investigators or predicted by the model. There is little difference in stapes motion in temporal bones when the inner ear is intact or drained.     

Ultrasonically determined thickness of long cortical bones: Three-dimensional simulations of in vitro experiments

It was reported in a previous study that simulated guided wave axial transmission velocities on two-dimensional (2D) numerically reproduced geometry of long bones predicted moderately real in vitro ultrasound data on the same bone samples. It was also shown that fitting of ultrasound velocity with simple analytical model yielded a precise estimate (UTh) for true cortical bone thickness. This current study expands the 2D bone model into three dimensions (3D). To this end, wave velocities and UTh were determined from experiments and from time-domain finite-difference simulations of wave propagation, both performed on a collection of 10 human radii (29 measurement sites). A 3D numerical bone model was developed with tuneable fixed material properties and individualized geometry based on X-ray computed tomography reconstructions of real bones. Simulated UTh data were in good accordance (root-mean-square error was 0.40 mm; r(2)=0.79, p<0.001) with true cortical thickness, and hence the measured phase velocity can be well estimated by using a simple analytical inversion model also in 3D. Prediction of in vitro data was improved significantly (by 10% units) and the upgraded bone model thus explained most of the variability (up to 95% when sites were carefully matched) observed in in vitro ultrasound data.     

A method for vibrational assessment of cortical bone

Large bones from many anatomical locations of the human skeleton consist of an outer shaft (cortex) surrounding a highly porous internal region (trabecular bone) whose structure is reminiscent of a disordered cubic network. Age related degradation of cortical and trabecular bone takes different forms. Trabecular bone weakens primarily by loss of connectivity of the porous network, and recent studies have shown that vibrational response can be used to obtain reliable estimates for loss of its strength. In contrast, cortical bone degrades via the accumulation of long fractures and changes in the level of mineralization of the bone tissue. In this paper, we model cortical bone by an initially solid specimen with uniform density to which long fractures are introduced; we find that, as in the case of trabecular bone, vibrational assessment provides more reliable estimates of residual strength in cortical bone than is possible using measurements of density or porosity.     

采用超声导波特征参量的骨质疏松识别方法

骨质的定期检测对骨质疏松的防治至关重要。本文研究了骨质疏松对超声导波在人体长骨中传播的影响。提出采用多尺度小波变换方法对接收到的导波信号进行处理,通过分析在不同传播距离下高阶小波细节分量所占信号总能量的变化,来判断是否患有骨质疏松症。在13位志愿者的小腿胫骨上进行超声测量,得到导波信号。经多尺度小波变换方法的分析处理结果显示在13位志愿者中,有7位志愿者的超声导波信号随着传播距离的改变,其主要频率成分发生了明显的变化,显示这7位志愿者患有骨质疏松症。这一诊断结果与X射线技术诊断结果相比,准确率可以达到92.3%,表明本文所提出的利用小波多尺度变换方法对长骨进行超声诊断具有较好的潜力。      

Diagnosis of osteoporosis based on multi-scale wavelet parameters of ultrasonic guided waves

Evaluating bone regularly is important to prevent and control the disease of osteoporosis. Impact of osteoporosis on ultrasonic guided waves propagating in human long bones is studied in this paper. Multi-scale wavelet transform is proposed to process the received guided waves, and by analyzing energy changes in detail components of high order wavelet at different propagating distance to assess if osteoporosis happened. The guided waves signals are collected from the tibias of 13 volunteers. Based on the analysis of multi-scale wavelet transform, the high order detail components d6 and d5 changed dramatically with the propagation of ultrasonic guided waves along long bones, which means these 7 volunteers are diagnosed with osteoporosis. Compared with X-ray diagnosis, the effectiveness of this method can reach 92.3% in 13 volunteers. This suggests the multi-scale wavelet transform method is potential in ultrasonic assessment of bone quality.     

Effect of trabecular bone material properties on ultrasonic backscattering signals

In this study, ultrasonic backscattering signals in cancellous bones were obtained by finite difference time domain （FDTD） simulations, and the effect of trabecular material properties on these signals was analyzed. The backscatter coefficient （BSC） and integrated backscatter coefficient （IBC） were numerically investigated for varying trabecular bone material properties, including density, Lame coefficients, viscosities, and resistance coefficients. The results show that the BSC is a complex function of trabecular bone density, and the IBC increases as density increases. The BSC and IBC increase with the first and second Lame coefficients. While not very sensitive to the second viscosity of the trabeculae, the BSC and IBC decrease as the first viscosity and resistance coefficients increase. The results demonstrate that, in addition to bone mineral density （BMD） and microarchitecture, trabecular material properties significantly influence ultrasonic backseattering signals in cancellous bones. This research furthers the understanding of ultrasonic backscattering in cancellous bones and the characterization of cancellous bone status.     

Use of Pulse-Echo Ultrasound Imaging in Transcranial Diagnostics of Brain Structures

The results are presented from computer simulations of acoustic pulse propagation in heterogenous media mimicking the human head in two-dimensional and three-dimensional geometries. In the three-dimensional experiment, the cranial bone is presented as a liquid layer with a speed of sound corresponding to that of longitudinal waves in the bone. In the two-dimensional experiment, both longitudinal and transverse waves are considered. Based on data obtained in the numerical experiments, the possibility of obtaining ultrasound images of point scatterers by compensating for aberrations introduced by cranial bones is studied. It is shown that even a simple time delay correction along straight rays greatly improves the quality of an ultrasound image obtained through a nonuniform-thickness solid layer.