Characterization of lead and lead leaching properties of lead glazed ceramics from the Solis Valley, Mexico, using inductively coupled plasma-mass spectrometry (ICP-MS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT)

Ingestion of relatively small amounts of lead is now recognized to cause significant neurological and cognitive effects in humans. Large quantities may be fatal, yet lead poisoning, especially of children, is still a major public health concern in many parts of the world. In rural Mexican communities lead oxide (PbO) is added to ceramic glaze as a fluxing agent, lowering starting firing temperatures to 500 °C. The purpose of this study is to characterize the lead chemical forms in ceramic glazes from the Solis Valley, Mexico, to investigate lead leaching properties of these ceramics, and to demonstrate the applicability of lead isotope signatures as a means of tracing lead source origins. Ceramics were collected from the rural village of Santa Maria de Canchesda, State of Mexico, Mexico. Dried liquid glazes, post-fired glaze material, and pure PbO were analyzed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). Results from DRIFT analysis indicate that PbO (1429 cm⁻¹ band) is the active form of lead found in liquid glazes and ceramics. Some shifting of 1429 cm⁻¹ PbO peak to lower wavenumbers occurs in post-fired ceramics, and this may be due to the formation of lead bisilicate during firing. Ceramics samples were leached in 0.02 M citric acid solution for 1 min, and leached lead concentrations were measured using inductively coupled plasma-mass spectrometry (ICP-MS). Lead concentrations in these leachates varied from 0.4-80.4 μg ml⁻¹, while the control pottery from the US leached only 0.1 μg ml⁻¹ lead. Elemental distributions on glaze surfaces were identified by laser ablation (LA)-ICP-MS. Nitric acid extracts of soils, teeth, and ceramic glazes were analyzed for lead isotope ratios (²⁰⁷Pb/²⁰⁶Pb vs. ²⁰⁸Pb/²⁰⁶Pb) using ICP-MS. Similarities of tooth and ceramic lead isotope ratios indicate that ceramics may be a substantial source of body lead burden in the Solis Valley. This study demonstrates the applicability of lead isotope ratios for lead source identification, and it identifies potential health risks from ceramic use induced lead toxicity within the Solis Valley.     

Mexican hat wavelet transform of distributions

Theory of Weierstrass transform is exploited to derive many interesting new properties of the Mexican hat wavelet transform. A real inversion formula in the differential operator form for the Mexican hat wavelet transform is established. Mexican hat wavelet transform of distributions is defined and its properties are studied. An approximation property of the distributional wavelet transform is investigated which is supported by a nice example.     

Dilatonic Dark Energy Model with Late Time de Sitter Attractor

Based on Weyl-scaled induced gravitational theory, we regard dilaton field in this theory as a candidate of dark energy. We construct a dilatonic dark energy model and its phantom model, that admit late time de Sitter attractor solution. When we take the potential of dilaton field as the form which has been studied in supergravity model and the famous Mexican hat potential , we show mathematically that these attractor solutions correspond to an equation of state ω = −1 and a cosmic density parameter Ω_σ = 1, which are important features for a dark energy model that can meet the current observations.     

Signal Analysis by New Mother Wavelets

Based on the general formula for finding qualified mother wavelets [Opt. Lett. 31 （2006） 407] we make wavelet transforms computed with the newly found mother wavelets （characteristic of the power 2n） for some optical Gaussian pulses, which exhibit the ability to measure frequency of the pulse more precisely and clearly. We also work with complex mother wavelets composed of new real mother wavelets, which offer the ability of obtaining phase information of the pulse as well as amplitude information. The analogy between the behavior of Hermite Gauss beams and that of new wavelet transforms is noticed.     

Heat source reconstruction from noisy temperature fields using an optimised derivative Gaussian filter

The aim of this paper is to present a post-processing technique based on a derivative Gaussian filter to reconstruct heat source fields from temperature fields measured by infrared thermography. Heat sources can be deduced from temperature variations thanks to the heat diffusion equation. Filtering and differentiating are key-issues which are closely related here because the temperature fields which are processed are unavoidably noisy. We focus here only on the diffusion term because it is the most difficult term to estimate in the procedure, the reason being that it involves spatial second derivatives (a Laplacian for isotropic materials). This quantity can be reasonably estimated using a convolution of the temperature variation fields with second derivatives of a Gaussian function. The study is first based on synthetic temperature variation fields corrupted by added noise. The filter is optimised in order to reconstruct at best the heat source fields. The influence of both the dimension and the level of a localised heat source is discussed. Obtained results are also compared with another type of processing based on an averaging filter. The second part of this study presents an application to experimental temperature fields measured with an infrared camera on a thin plate in aluminium alloy. Heat sources are generated with an electric heating patch glued on the specimen surface. Heat source fields reconstructed from measured temperature fields are compared with the imposed heat sources. Obtained results illustrate the relevancy of the derivative Gaussian filter to reliably extract heat sources from noisy temperature fields for the experimental thermomechanics of materials.     

光学小波匹配滤波器与图形识别

小波变换弥补了傅里叶变换的不足，在信号及图像处理方面具有广阔的应用前景。文章深入讨论了小波变换匹配滤波器的理论基础及光学实现方法，并将其用于图形识别，给出了计算机模拟结果，与传统的匹配滤波器进行了比较，证实了小波变换在光学信息处理中的优越性。     

Steam distillation and supercritical fluid extraction of some Mexican spices

Summary By means of steam distillation and supercritical fluid extractions, we are in a process of evaluating the essential oil and the oleoresin quality and yield obtain respectively by the above methods outlined.Our area of interest is the isolation, separation and purification of compounds whose applications are well supported by the food technology demands.We pretend to characterize the aromatic components of edible or other commercial oils from the widespread spices and plant natural collections, throughout the country of Mexico.The facilities for the obtention of reference standards characteristic of our flora specimens, is under research.Poster presented at the First Symposium of Supercritical Fluids, Nice, France, 14–17 October, 1988     

光谱信号的小波去噪新技术

光谱分析中,噪声的存在常影响分析的准确度和检测限。现有滤波方法在光谱信号除噪方面有种种缺陷。文章充分利用小波在信号处理方面的优良特性,提出了Mexican Hat小波滤波算法,它选用Mexican Hat小波函数构造滤波项,利用滤波项与原始信号作用,从而实现信号与噪音的分离。该方法无论对低频或高频信号均适用,除噪完全,即使对信噪比为1的高噪声信号也能获取满意的处理结果。运用这一技术处理光谱信号,简单快速、结果可靠,处理后峰位置、峰高、峰面积误差分别小于0.2%,3.2%,1.1%。大量实验表明,本方法能有效提高光谱分析的准确度。     

Wavelet Analysis of the Evolution of a Solitary Wave in a Composite Material

The evolution of a solitary wave propagating through a microstructural material (composite) is studied on the basis of wavelet analysis. A specific feature of the solution technique proposed is the use of Mexican hat (MH) wavelets, which are elastic wavelets, i.e., they are solutions of the basic system of wave equations for an elastic material with a microstructure. The initial wave profile is also chosen in the form of the MH-wavelet. Primary attention is given to the relationship among the profile behavior, wave bottom length, and characteristic microstructure length. A computer analysis conducted demonstrates that the approach proposed allows us to detect the basic wave effects: splitting of the wave into two modes with different phase velocities, simultaneous propagation of both modes in the components of the composite, and strong dependence of the evolution rate on the characteristic lengths of the wave and microstructure