A new four-point probe design to measure conductivity in polymeric thin films

In the development of new conducting polymers applications,the conductivity measurement is still a challenge, specially for extremely thin samples as the ones obtained by CVD. This study shows the design of a novel four-point probe for conductivity characterization of polypirrole thin films synthesized by plasma enhanced polymerization.The system possesses the minimal distance possible among electrodes, together with a high ratio of electrode length to spacing to enhance the electrical response. The four-point probe has been fabricated in a printed circuit board, which offers some advantages such as non-damaging samples, low cost or repeatability in the analysis measurements

Determination of squalene by-products during model compound vulcanization studies by LC-ESI-MS using silver nitrate as a post-column reagent

High Performance Liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) using silvernitrate as a post-column reagent has been used for the determination of squalene by-products during model compound vulcanization studies. In this method, after all by-products were separated by reverse-phase liquid chromatography, analytes formed complexes with silver cation by mixing with a silver nitrate solution. The positive ion ESI mass spectra of squalene, squalene by-products and intermediates of vulcanization process showed [M+Ag]+ and/or [M+Ag+AgNO3]+ ions. The method described in this paper overcomes the ESI technique limitations related to the ionization of hydrocarbon. Furthermore, results obtained working with this methodology helped to gain more insight into the natural rubber accelerated vulcanization process. In this sense the identification of the different crosslink types was determined, proving that the elution time increases with the decrease of sulfur chain length inthe crosslink. Squalene with pendant group was also identified

Flexural properties and failure mechanism assessment for additive manufactured lom bars on different building orientations

Plastic Laminated Object Manufacturing has not been assessed from the flexural properties point of view. The deflection range in parts manufactured by this technique is wider than in parts fabricated by other additive manufacturing methods like SLS or FDM. This fact has increased the interest on the final application of these parts rather than restricted to Rapid Prototyping applications. In this study it will be compared the impact of building orientation and geometric features of parts over the flexural properties. Through optical observation it will be studied the failure mechanism.Postprint (published version

Small average differences in attenuation corrected images between men and women in myocardial perfusion scintigraphy: a novel normal stress database

<p>Abstract</p> <p>Background</p> <p>The American Society of Nuclear Cardiology and the Society of Nuclear Medicine state that incorporation of attenuation-corrected (AC) images in myocardial perfusion scintigraphy (MPS) will improve image quality, interpretive certainty, and diagnostic accuracy. However, commonly used software packages for MPS usually include normal stress databases for non-attenuation corrected (NC) images but not for attenuation-corrected (AC) images. The aim of the study was to develop and compare different normal stress databases for MPS in relation to NC vs. AC images, male vs. female gender, and presence vs. absence of obesity. The principal hypothesis was that differences in mean count values between men and women would be smaller with AC than NC images, thereby allowing for construction and use of gender-independent AC stress database.</p> <p>Methods</p> <p>Normal stress perfusion databases were developed with data from 126 male and 205 female patients with normal MPS. The following comparisons were performed for all patients and separately for normal weight vs. obese patients: men vs. women for AC; men vs. women for NC; AC vs. NC for men; and AC vs. NC for women.</p> <p>Results</p> <p>When comparing AC for men vs. women, only minor differences in mean count values were observed, and there were no differences for normal weight vs. obese patients. For all other analyses major differences were found, particularly for the inferior wall.</p> <p>Conclusions</p> <p>The results support the hypothesis that it is possible to use not only gender independent but also weight independent AC stress databases.</p

Detection of peptide-based nanoparticles in blood plasma by ELISA

Aims: The aim of the current study was to develop a method to detect peptide-linked nanoparticles in blood plasma. Materials & Methods: A convenient enzyme linked immunosorbent assay (ELISA) was developed for the detection of peptides functionalized with biotin and fluorescein groups. As a proof of principle, polymerized pentafluorophenyl methacrylate nanoparticles linked to biotin-carboxyfluorescein labeled peptides were intravenously injected in Wistar rats. Serial blood plasma samples were analyzed by ELISA and by liquid chromatography mass spectrometry (LC/MS) technology. Results: The ELISA based method for the detection of FITC labeled peptides had a detection limit of 1 ng/mL. We were able to accurately measure peptides bound to pentafluorophenyl meth-acrylate nanoparticles in blood plasma of rats, and similar results were obtained by LC/MS. Conclusions: We detected FITC-labeled peptides on pentafluorophenyl methacrylate nanoparticles after injection in vivo. This method can be extended to detect nanoparticles with different chemical compositions

New Developments in Vertebroplasty Materials

Increasing life expectancy is leading to an increase inage-related diseases, like osteoporosis, which often involve the breakdown of bone. One of the main problems related with such disease is the formation of vertebral compression fractures (VCF). The impact of the vertebral compression fractures that have been describedis diverse, such as distortion in the spine (kyphosis), chronic back pain, reduced physical function with risk of immobility, decline of lung function, gastroesophagealreflux and change in appearance that may led tosocial isolation, loss of self-esteem and depression. Vertebral fracture is just the beginning of the constant deterioration of the health of the affected patients. Until now, the treatments applied in this type of fracture are mainly three: conservative medicaltreatment, invasive surgical intervention, and vertebroplasty and kyphoplasty. These last two techniques,minimally invasive, have shown interesting resultsthough there is still room for improvement, especially due to the lack of an ideal bone cement material. In this review, we will focus on the recent developments in vertebroplasty, their pros and cons and the needs for further achievements. We therefore begin with a brief description of vertebroplasty followed with a description of the biomechanical and the osteoregeneration needs that materials should ful fill to be useful in this application. Finally, we describe the recent materials developments for vertebroplasty and the different proposals for improvement

Preservation of copper against atmospheric corrosion with a film obtained by plasma polymerization of methane

Ancient calcographic plates made of copper metal were restored by cleaning the residual dry ink by means of a surface plasma etching. The clean copper plates require some additional surface preservation in order to protect them against further atmospheric oxidation and corrosion. We studied the properties of polymer film coatings on the copper plates. The films were obtained by plasma polymerization of methane gas in a low pressure R.F. reactor. We then studied the surface free energy of the films and their resistance to ketone solvent. We evaluated thermal stability by thermogravimetric analysis and their aging behavior by accelerated climatic tests. The electrochemical behavior of the films was characterized by impedance spectroscopy and polarization curves

Plasma polymer thin films obtained by plasma polymerization of pyrrole

Thin films obtained by plasma polymerization of pyrrole were deposited on different substrates. The polymer films were obtained in a R.F. plasma polymerization reactor from low-pressure vapor of the pyrrole monomer. The R.F. power and gas pressure were adjusted to obtain optimal deposition rate and film adhesion to substrates. The film composition was determined using InfraRed Transmission and X-ray Photoelectron Spectroscopy (XPS)

Flexural properties and failure mechanism assessment for additive manufactured lom bars on different building orientations

Plastic Laminated Object Manufacturing has not been assessed from the flexural properties point of view. The deflection range in parts manufactured by this technique is wider than in parts fabricated by other additive manufacturing methods like SLS or FDM. This fact has increased the interest on the final application of these parts rather than restricted to Rapid Prototyping applications. In this study it will be compared the impact of building orientation and geometric features of parts over the flexural properties. Through optical observation it will be studied the failure mechanism