Search

Several radiotracers have been used for assessing cell death, whether by necrosis or apoptosis.99mTc glucarate, which has initially been reported to be concentrating/accumulating in myocardial infarction or zones of cerebral injury, has also shown some tumor-seeking properties in a few preliminary studies. Under International Atomic Energy Agency (IAEA)'s coordinated research program, we report here the standardization, quality control, and clinical evaluation (detection, evaluation of response, and comparison with 18F Fluorodeoxyglucose) of this tracer in well-characterized lung cancer and head neck malignancies in a single-arm prospective observational study. Forty-seven patients (29 inoperable lung carcinoma and 18 head and neck malignancies) were prospectively enrolled and underwent 99mTc glucarate imaging [whole body planar and single-photon emission computed tomography of the region of interest] 4-5 hours after injection of 20 mCi of the radiopharmaceutical. Excellent 99mTc glucarate concentration was noted in the target lesion in lung cancer and head and neck malignancies. The sensitivity was found to be better in lung cancer. Avid concentration of tracer was seen in the metastatic sites. During response evaluation, the glucarate concentration correlated well with the clinical and other radiological indings. 99mTc glucarate showed avid concentration of tracer in the tumor, suggesting it to be a potential tumor imaging agent which can be used for detection and assessment of therapeutic response in malignancy. [ABSTRACT FROM AUTHOR]

This work aims to develop a stereoselective enzymatic alternative for the radiosynthesis of [11C] (S,S) -S-adenosylmethionine ([11C](S,S)-SAM), a potential PET-CT radiotracer for monitoring particularly aggressive prostate tumors. Conventional synthesis of this compound has been carried out at Uruguayan Center of Molecular Imaging, resulting in an almost racemic mixture 53:47 ratio of (R,S) to (S,S) isomer. Producing the radiotracer in an optically pure form is a requirement for administration to humans and additionally it would enhance diagnostic sensitivity when administered to the patient. The main challenges were designing a biocatalyst capable of withstanding the harsh conditions of the radiotracer synthesis module and achieving the reaction in a very short time due to the rapid decay of 11C. A mutant of E. coli methionine adenosyltransferase (I303V MAT) with enhanced SAM synthesis was cloned, expressed, and immobilized on agarose using an irreversible covalent isourea bond. This immobilized enzyme synthesized [11C](S,S)-SAM from [11C]L-methionine in an automated module, with the labeled methionine produced in situ from [11C]CH3I and L-homocysteine thiolactone. The product was obtained with an enantio and diasteromeric excess greater than 99 % and average conversion of 80 %. The reuse of the immobilized enzyme was studied, showing that after three cycles of reuse the radiosynthesis performance remained unchanged. [Display omitted] • Immobilization of I303V methyl adenosyltransferase (I303V MAT) for radiosynthesis. • Enzymatic radiosynthesis of (S,S)-S-adenosyl methionine using immobilized I303V MAT. • [11C](S,S)-S-adenosyl methionine synthesis was achieved with 80 % conversion. • [11C](S,S)-S-adenosyl methionine was achieved with > 99 % optical purity. • Adaptation of enzymatic radiosynthesis to an automated module. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes assumptions, aims, methodology, content and consortium make up of a European project (SAM–EMU) founded under the Erasmus Lifelong Learning Programme. The project has developed learning materials in the field of evaluation of measurement uncertainty. It is available in the form of a multimedia web based course, which has many advantages. This format is commonly accepted as a good way to prepare an EU wide vocational training vehicle. The course is available in English. [Copyright &y& Elsevier]

The primary role of hard turning is to realize surfaces with high dimensional accuracy and high surface integrity to improve functional performances of the manufactured product. To this aim, the turning process parameters have to be carefully chosen. The present work deals with the correlation between hard turning parameters, surface and sub-surface characteristics, and corrosion behavior of the AISI 52100 bearing steel. Different cutting speeds and cooling conditions, specifically conventional flood and cryogenic cooling, were used for hard turning. Microstructural observations, residual stresses, nano-hardness, and surface finish measurements were carried out to assess the surface integrity modifications induced by machining. Then, potentiodynamic polarization curves were carried out, and the corroded surfaces were inspected. The obtained results showed that a remarkably improved corrosion resistance was obtained by using the lowest adopted cutting speed coupled with cryogenic cooling. Specifically, the former contributed to generate a wider nanostructure layer close to the machined surface, while the latter induced compressive residual stress state in correspondence of it. [ABSTRACT FROM AUTHOR]

The present paper is aimed at investigating the effect of shot peening on the high and very-high cycle plain fatigue resistance of the Al-7075-T651 alloy. Pulsating bending fatigue tests ( R = 0.05) were carried out on smooth samples exploring fatigue lives comprised between 10 5 and 10 8 cycles. Three peening treatments were considered to explore different initial residual stress profiles and surface microstructural conditions. An extensive analysis of the residual stress field was carried out by measuring with the X-ray diffraction (XRD) technique the residual stress profile before and at the end of the fatigue tests. Fatigue crack initiation sites were investigated through scanning electron microscopy (SEM) fractography. The surface morphology modifications induced by shot peening were evaluated using an optical profilometer. The influence of surface finishing on the fatigue resistance was quantified by eliminating the surface roughness in some peened specimens through a tribofinishing treatment. The capability of shot peening to hinder the initiation and to retard the subsequent propagation of surface cracks is discussed on the basis of a model combining a multiaxial fatigue criterion and a fracture mechanics approach. [ABSTRACT FROM AUTHOR]

Abstract: Scanning Probe Microscopy (SPM) imaging process is inherently slow, and commonly suffers from instrumental drift. According to experience, drift is a time dependent phenomenon and therefore it influences measurement results obtained using the instruments for long periods of time, e.g. when high resolution imaging is performed by taking many profiles. Evaluation and control of actuator drift is an important issue for high accuracy measurements. In particular, a better probe positioning can be obtained through characterization of the scanning system’s metrological performance, and distinguishing systematic and stochastic behavior components. In this work, a new approach is proposed to study long term thermal phenomena, correlating them to SPM scanner drift distortions evaluated using calibrated reference samples. Long term drift evaluation is then cross-correlated to thermal analyses carried out in parallel by means of an infrared-camera. Eventually, it is discussed how the investigations here presented may be used to improve the instrument set-up in order to reduce measurement uncertainty. [Copyright &y& Elsevier]

Abstract: Atomic force acoustic microscopy is an interesting measurement technique for characterization and mapping of local elastic properties of different materials, taking advantage of high lateral resolutions typical of scanning probe instruments. The present work discusses applicability of the technique and the main factors to be considered for exploitation of quantitative measurements. Particular attention is given to the influence of tips and to the role of calibration. Investigations and comparison with nanoindentation technique are eventually reported on different samples produced by means of plasma enhanced chemical vapour deposition technique (PECVD). [Copyright &y& Elsevier]

Abstract: Replaced hip joints are normally expected to last 15–20 years. However, although the procedure is nowadays successfully performed, up to 10% of procedures carried out are revision operations to replace joints, which have failed prematurely, mainly in case of polymeric or metallic bearing surfaces. In fact, particulate debris, generated by wear of the bearing surfaces, are “attacked” by the immune system which results in the death of surrounding bone tissue which in turn leads to loosening of the joint and pain to the patient. All-ceramic hip replacements were introduced to eliminate this mechanism and reduce wear. The most common method to evaluate wear volumes in hip joints is the gravimetric method, which has been proven to be straightforward and accurate. However, this method can only be applied during in vitro testing of new hip prostheses and not to assess retrieved components. Furthermore, even in case of in vitro testing, it can globally quantify the worn material, while it cannot provide local information on the worn surface geometry. Coordinate measuring machines (CMMs) can be used to evaluate both wear volume and wear distribution over the worn surface. However, the uncertainty of wear volume measurements from CMM data has not been thoroughly quantified yet. This work makes a step further, establishing an approach for uncertainty analysis and quantification. The paper focuses on evaluation of uncertainty components that affect wear volume measurements. In particular, nine ceramic femoral heads were analysed with both gravimetric and CMM methods in order to assess the uncertainty of wear volume measurements and compare these two methodologies. The results of this investigation showed that wear volume measurements from CMM data are in good agreement with gravimetric measurements, taking into account measurement uncertainty of both methods according to the “Guide to the expression of uncertainty in measurement (GUM)” and derived documents. Furthermore, the study uses the uncertainty analysis to optimize the probing strategy and suggests improvements to ISO 14242-2:2000. [Copyright &y& Elsevier]

This paper aimed at identifying the error sources that occur in dimensional measurements performed using atomic force microscopy. In particular, a set of characterization techniques for errors quantification is presented. The discussion on error sources is organized in four main categories: scanning system, tip-surface interaction, environment, and data processing. The discussed errors include scaling effects, squareness errors, hysteresis, creep, tip convolution, and thermal drift. A mathematical model of the measurement system is eventually described, as a reference basis for errors characterization, with an applicative example on a reference silicon grating. [ABSTRACT FROM AUTHOR]

Summary Contradicting results concerning IOP control and visual field deterioration are presented. Some of these inconsistencies may be due to the statistical method of analysis. Sixty POAG patients with a perimetric follow-up over 3 years were selected. Mean and maximum IOPs were considered during the same period. The patients were divided into two groups according to the IOP control (well controlled or poorly controlled). Visual field progression was defined as a reduction in sensitivity over the fifth percentile in more than four points. Mean IOPs were not significantly different in the group of patients with a visual field deterioration compared to the stable ones, but the percentage of patients with a visual field deterioration was significantly higher in patients with higher IOPs. This holds especially true if IOP below 16 mmHg (G) is considered the ‘target pressure’. IOP reduction seems to play an essential role in visual field progression. In glaucomatous patients, a strict (<16 mmHg (G)) might be necessary. [ABSTRACT FROM AUTHOR]