[en] A method of analysis of scattering amplitudes which consists in representing the experimental data through analytical functions of a certain kind is described. Starting from measurements of polarization and differential cross section for a given energy, the scattering amplitudes are built in terms of the Barrelet zeros, wich are zeros occurring for complex values of the variable cos (theta) extended to the complex plane. (Author)

[en] Short communication

[en] Glass-ceramics in the LAS (Li₂ O-Al₂ O₃ -SiO₂ ) system with high thermal shock resistance were successfully obtained using Brazilian spodumene concentrate as the main raw material (80-70 wt%). Two compositions (Li₂ O.Al₂ O₃ .nSiO₂ ) were produced with n= 2 and 4, near to the stoichiometric compositions of β-eucryptite and β-spodumene. The characteristic temperatures of parent glasses were determined by contact dilatometry, differential scanning calorimetry and heating microscopy. The crystallization mechanism and the effect of the nucleating agent (TiO₂ .2ZrO₂ ) required to promote volume crystallization in the parent glasses were investigated. Microstructural and structural changes with temperature were also evaluated by optical microscopy and X-ray diffraction. The obtained glass-ceramics presented coefficients of thermal expansion between -0.370x10^-6 and 4.501x10^-6 °C^-1 in the 22 to 700 °C range. (author)

[en] Complete text of publication follows. Miniaturization of the analytical methodology represents a current trend that brings about a higher degree of simplification and automatization, yet different stages of the analytical process have their own challenges. During last decade, several alternatives to classical approaches for separation and preconcentration have been proposed with the aim of decreasing the volume of the extractant phase. Thus, through miniaturization of classical liquid-liquid extraction (LLE), several techniques have emerged, such as single-drop microextraction (SDME), being the most important, hollow-fibre liquid-phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME). In this work, several examples of SDME methods for ultratrace analysis and speciation using both headspace and immersed approaches along with detection techniques sucha ETAAS, GC-MS, HPLC-UV and UV-Vis spectrophotometry will be discussed. Acknowledgements. Financial support from the Spanish Education and Science Ministry (project CTQ2006-04111/BQU) is gratefully acknowledged. This work has been undertaken as part of the EU sponsored COST Programme (Action D32, working group D32/005/04).

[en] Full text: The aim of this work is to present results related to solid state reactions on LZSA glass-ceramic composites containing alumina reinforcement nano-particles. A LZSA (Li2O-ZrO2-SiO2-Al2O3) glass-ceramic has been prepared by sintering of powders and characterized. Composites containing 0 to 77 vol.% of alumina nanoparticles (27-43 nm APS, 35 m2.g-1 SSA) and a 16.9Li2O•5.0ZrO2•65.1SiO2•8.6Al2O3 glass-ceramic matrix have been prepared. X-ray diffractometry studies have been performed in order of investigating the solid state reactions occurring in LZSA-based composites. Results of the XRD patterns have been related to the coefficient of thermal expansion (CTE), Young modulus, and dielectric constant, showing that, in comparison with the glass-ceramic composition, the composites showed a decrease of CTE with the alumina concentration increasing, due to the increasing of beta-spodumeness formation (solid solution of beta-spodumene, Li2O.Al2O3.4-10SiO2). The performance of the glass-ceramic was improved with the alumina nano-particles addition, showing potential of using in the preparation of Low Thermal Co-fired Ceramics (LTCC). (author)

[en] To assess the dose performance in terms of image quality of filtered back projection (FBP) and two generations of iterative reconstruction (IR) algorithms developed by the most common CT vendors. We used four CT systems equipped with a hybrid/statistical IR (H/SIR) and a full/partial/advanced model-based IR (MBIR) algorithms. Acquisitions were performed on an ACR phantom at five dose levels. Raw data were reconstructed using a standard soft tissue kernel for FBP and one iterative level of the two IR algorithm generations. The noise power spectrum (NPS) and the task-based transfer function (TTF) were computed. A detectability index (d′) was computed to model the detection task of a large mass in the liver (large feature; 120 HU and 25-mm diameter) and a small calcification (small feature; 500 HU and 1.5-mm diameter). With H/SIR, the highest values of d′ for both features were found for Siemens, then for Canon and the lowest values for Philips and GE. For the large feature, potential dose reductions with MBIR compared with H/SIR were − 35% for GE, − 62% for Philips, and − 13% for Siemens; for the small feature, corresponding reductions were − 45%, − 78%, and − 14%, respectively. With the Canon system, a potential dose reduction of − 32% was observed only for the small feature with MBIR compared with the H/SIR algorithm. For the large feature, the dose increased by 100%. This multivendor comparison of several versions of IR algorithms allowed to compare the different evolution within each vendor. The use of d′ is highly adapted and robust for an optimization process.

[en] High-heterogeneity solid woven fabric samples were investigated using laser-induced breakdown spectroscopy (LIBS) and chemometrics. Many emission lines were relevant to characterize this material at the surface and in deeper layers of fibers. Differences among dyes and fibers were clearly observed. The scores maps showed the possibility of comparing the chemical compositions of the dye and fiber independent of the print of fabric. Variations in the composition were verified by carrying out a pattern for mapping using a sophisticated LIBS system. This screening can provide a fast evaluation of samples and may associate this information with classification, authenticity or even for forensic analysis of fabric materials.

[en] Complete text of publication follows. The distribution of Ag, As, Cd, Co, Cu, Cr, Mn, Mo, Ni, Pb, Se, Zn, Al, Ca, Fe, K, Mg, P and S in human breast cancerous and non-cancerous biopsies has been established. Forty-seven biopsies from thirty-nine women were analyzed: 20 samples corresponding to mammoplasties from healthy women and 27 samples from patients suffering from cancer pathology, 19 of which corresponded to tumour and 8 to adjacent normal tissue. A microwave-assisted digestion method suited to analysis of small size biological samples has been developed prior to elemental determination by inductively coupled plasma-mass spectrometry (ICP-MS) and inductively-coupled plasma optical emission spectrometry (ICP-OES). Screening optimization of the microdigestions was carried out using factorial designs No significant effects of the main variables influencing MW-assisted digestion were found, the digestion method being robust enough to be recommended for a routine practice. Procedural detection limits ranged from 0.54 to 40 ng/g by ICP-MS and 10-10000 ng/g by ICP-OES. After applying parametric and non-parametric statistical tests, a significant accumulation of Cu, Mn, Zn, Se Al, Ca, K, Mg, Mn, P in cancerous tissues as compared to healthy tissues was demonstrated. Acknowledgements. The authors thank Dra Pilar Sanmiguel from the anatomy pathological service of the POVISA Hospital (Vigo, Spain) for providing the biopsies.

[en] Studies have proven that the use of waste in the production of clay ceramics is common for achieving the technical performance that is necessary for the application of these by-products. However, it is essential to analyze the feasibility of using these materials in terms of productivity and economic gains, in line with sustainability. The objective of this study is to determine the cost-benefit ratio of using rice husk ash in the production of clay ceramics. The methodological process consisted of a comparative analysis on an industrial scale between the formulation with up to 15% by volume of rice husk ash and the standard formulation previously used by the company. The economic aspects included the costs/consumption of raw materials, transport, and energy. The productivity throughout the process and technical characteristics of the final product were also evaluated. The costs of raw materials showed a financial gain of 7.0%, whereas the productivity analysis revealed that the greatest economic gain was in energy consumption during drying (13%). (author)

[en] The functional dependence of the high-energy observables of the total cross section and slope parameter on the sizes of the colliding hadrons predicted by the model of the stochastic vacuum and the corresponding relations used in the geometric model of Povh and Huefner are confronted with the experimental data. The existence of a universal term in the expression for the slope, due purely to vacuum effects, independent of the energy and of the particular hadronic system, is investigated. copyright 1997 The American Physical Society