Augmentation of the mechanical and chemical resistance characteristics of an Al2O3-based refractory by means of high power diode laser surface treatment

Augmentation of the wear rate and wear life characteristics of an Al2O3-based refractory within both normal and corrosive (NaOH and HNO3) environmental conditions was effected by means of high power diode laser (HPDL) surface treatment. Life assessment testing revealed that the HPDL generated glaze increased the wear life of the Al2O3-based refractory by 1.27 to 13.44 times depending upon the environmental conditions. Such improvements are attributed to the fact that after laser treatment, the microstructure of the Al2O3-based refractory was altered from a porous, randomly ordered structure, to a much more dense and consolidated structure that contained fewer cracks and porosities. In a world economy that is increasingly placing more importance on material conservation, a technique of this kind for delaying the unavoidable erosion (wear) and corrosion that materials such as the Al2O3-based refractory must face may provide an economically attractive option for contemporary engineers

Determination of the absorption length of CO2, Nd:YAG and high power diode laser radiation for a selected grouting material

The laser beam absorption lengths of CO2, Nd:YAG and a high power diode laser (HPDL) radiation for a newly developed SiO2/Al2O3-based tile grout have been determined through the application of Beer-Lambert’s law. The findings revealed marked differences in the absorption lengths despite the material having similar beam absorption coefficients for the lasers. The absorption lengths for the SiO2/Al2O3-based tile grout for CO2, Nd:YAG and HPDL radiation were calculated as being 23211 m, 1934 m and 1838 m respectively. Moreover, this method of laser beam absorption length determination, which has hitherto been used predominantly with lasers operated in the pulsed mode, is shown to be valid for use with lasers operated in the continuous wave (CW) mode, depending upon the material being treated

Development of marine-based nanocomposite scaffolds for biomedical applications

Despite the increasing attention that marine organisms are receiving, many of those are not efficiently exploited and subproducts with valuable compounds are being discarded. Two examples of those subproducts are the endoskeleton of squid, from which β-­‐chitin and consecutively chitosan can be obtained; and fish-­‐bones, as a source for the production of nano-­‐ hydroxyapatite. In this work, inspired in the nanocomposite structure of human bone, marine-­‐ based nanocomposite scaffolds composed by chitosan and nano-­‐hydroxyapatite (nHA) were developed using particle aggregation methodology. Chitosan was obtained from endoskeleton of giant squid Dosidicus Gigas while fish hydroxyapatite nanoparticles were synthesized from fish-­‐bones by pulsed laser in deionized water. An innovative methodology was used based on the agglomeration of prefabricated microspheres of chitosan/nHA, generally based on the random packing of microspheres with further aggregation by physical or thermal means to create a marine nanocomposite (CHA) .The morphological analysis of the developed nanocomposites revealed a low porosity structure, but with high interconnectivity, for all produced scaffolds. Furthermore, the nanocomposite scaffolds were characterized in terms of their mechanical properties, bioactivity, crystallinity and biological behavior. The obtained results highlight that the chitosan/nHA-­‐based marine nanocomposite can be a good candidate for biomedical applications, namely on bone regeneration

Semiconductor gellan gum based composite hydrogels for tissue engineering applications

Publicado em "Journal of Tissue Engineering and Regenerative Medicine", vol. 7, supp. 1 (2013)Semiconductor hydrogels can be developed by combining the intrinsic electrical properties of semiconductors with the specific characteristics of hydrogels. These hydrogels have recently attracted much attention for applications in tissue engineering, especially formulations incorporating pyrrole and excellent biocompatibility. Several studies have reported that electrical stimulation influences the migration, proliferation and differentiation of stem cells and other cell lines [1]. The goal of this work is to use in situ chemical polymerization of polypyrrole (PPy) with gellan gum (GG) in order to obtain a new generation of semiconductor composite hydrogels. For the synthesis of GG/PPy composites, GG at 1.25% (w/v) final concentration was prepared in distilled water at room temperature. The solution was then heated under stirring at 90°C for 20 min. Temperature was decreased to 65°C and Py was added under vigorous agitation. The crosslinker solution (CaCl2, 0.18%) was added at 50°C. After 2 h, GG/Py composite hydrogels were obtained. In a further step, GG/Py samples were immersed in a solution of oxidizing agent in PBS and the reaction was carried out for 18 h under agitation at room temperature. Finally, the samples were frozen at -80°C for 48 h and lyophilized. The characterization of GG, GG/PPy and PPy samples was performed by scanning electron microscopy (SEM). The incorporation of PPy in the gellan gum was confirmed by SEM analysis. The coating with PPy increases the thickness of each sheet in 3 fold when compared with GG samples. Conductivity tests were also performed. For cytotoxicity assay, the samples were rehydrated with complete culture medium. MTS and DNA quantification assays were performed to evaluate the metabolic activity and proliferation of L929 fibroblast cells after 1, 3 and 7 days in culture with GG, GG/PPy and PPy samples. MTS assays clearly indicate a proportional relation between the cell viability and the PPy concentration: higher concentrations of PPy resulted in lower cell viability. These results show that lower concentration of PPy incorporated in the GG hydrogels can provide an adequate electrical stimulus to improve cell behavior. In conclusion, semiconductor hydrogels can be an excellent platform for tissue engineering and electrochemical therapy application

Surface treatment of an Al2O3-based refractory with CO2 and high power diode lasers for improved mechanical and chemical resistance characteristics

Within both normal and corrosive (NaOH and HNO3) environmental conditions, the wear rate and wear life characteristics of an Al2O3-based refractory were greatly enhanced by means of CO2 and high power diode laser (HPDL) surface treatment. Such improvements are attributed to the fact that after laser treatment, the microstructure of the Al2O3-based refractory was altered from a porous, randomly ordered structure, to a much more dense and consolidated structure that contained fewer cracks and porosities. What is more, resulting from the different rates of solidification brought about by differences in the wavelengths of the two lasers, dissimilar microstructures were subsequently generated. Indeed, despite the fact that the glaze thickness was less, the wear life of the HPDL treated surface exceeded that of the CO2 laser treated surface in all the test environments owing to its finer, more densely packed and less cracked microstructure

Innovative Therapeutic and Delivery Approaches Using Nanotechnology to Correct Splicing Defects Underlying Disease

Alternative splicing of pre-mRNA contributes strongly to the diversity of cell- and tissue-specific protein expression patterns. Global transcriptome analyses have suggested that >90% of human multiexon genes are alternatively spliced. Alterations in the splicing process cause missplicing events that lead to genetic diseases and pathologies, including various neurological disorders, cancers, and muscular dystrophies. In recent decades, research has helped to elucidate the mechanisms regulating alternative splicing and, in some cases, to reveal how dysregulation of these mechanisms leads to disease. The resulting knowledge has enabled the design of novel therapeutic strategies for correction of splicing-derived pathologies. In this review, we focus primarily on therapeutic approaches targeting splicing, and we highlight nanotechnology-based gene delivery applications that address the challenges and barriers facing nucleic acid-based therapeutics

Population pharmacokinetics of ganciclovir after intravenous ganciclovir and oral valganciclovir administration in solid organ transplant patients infected with cytomegalovirus

A population pharmacokinetics analysis was performed after intravenous ganciclovir and oral valganciclovir in solid organ transplant patients with cytomegalovirus. Patients received ganciclovir at 5 mg/kg of body weight (5 days) and then 900 mg of valganciclovir (16 days), both twice daily with dose adjustment for renal function. A total of 382 serum concentrations from days 5 and 15 were analyzed with NONMEM VI. Renal function given by creatinine clearance (CL(CR)) was the most influential covariate in CL. The final pharmacokinetic parameters were as follows: ganciclovir clearance (CL) was 7.49.(CL(CR)/57) liter/h (57 was the mean population value of CL(CR)); the central and peripheral distribution volumes were 31.9 liters and 32.0 liters, respectively; intercompartmental clearance was 10.2 liter/h; the first-order absorption rate constant was 0.895 h(-1); bioavailability was 0.825; and lag time was 0.382 h. The CL(CR) was the best predictor of CL, making dose adjustment by this covariate important to achieve the most efficacious ganciclovir exposure

Using metallic noncontact atomic force microscope tips for imaging insulators and polar molecules: tip characterization and imaging mechanisms

We demonstrate that using metallic tips for noncontact atomic force microscopy (NC-AFM) imaging at relatively large (>0.5 nm) tip-surface separations provides a reliable method for studying molecules on insulating surfaces with chemical resolution and greatly reduces the complexity of interpreting experimental data. The experimental NC-AFM imaging and theoretical simulations were carried out for the NiO(001) surface as well as adsorbed CO and Co-Salen molecules using Cr-coated Si tips. The experimental results and density functional theory calculations confirm that metallic tips possess a permanent electric dipole moment with its positive end oriented toward the sample. By analyzing the experimental data, we could directly determine the dipole moment of the Cr-coated tip. A model representing the metallic tip as a point dipole is described and shown to produce NC-AFM images of individual CO molecules adsorbed onto NiO(001) in good quantitative agreement with experimental results. Finally, we discuss methods for characterizing the structure of metal-coated tips and the application of these tips to imaging dipoles of large adsorbed molecules. © 2014 American Chemical Society

Chikungunya virus infections among travellers returning to Spain, 2008 to 2014

Since the first documented autochthonous transmission of chikungunya virus in the Caribbean island of Saint Martin in 2013, the infection has been reported within the Caribbean region as well as North, Central and South America. The risk of autochthonous transmission of chikungunya virus becoming established in Spain may be elevated due to the large numbers of travellers returning to Spain from countries affected by the 2013 epidemic in the Caribbean and South America, as well as the existence of the Aedes albopictus vector in certain parts of Spain. We retrospectively analysed the laboratory diagnostic database of the National Centre for Microbiology, Institute of Health Carlos III (CNM-ISCIII) from 2008 to 2014. During the study period, 264 confirmed cases, of 1,371 suspected cases, were diagnosed at the CNM-ISCIII. In 2014 alone, there were 234 confirmed cases. The highest number of confirmed cases were reported from the Dominican Republic (n = 136), Venezuela (n = 30) and Haiti (n = 11). Six cases were viraemic in areas of Spain where the vector is present. This report highlights the need for integrated active case and vector surveillance in Spain and other parts of Europe where chikungunya virus may be introduced by returning travellers

Age of Child, More than HPV Type, Is Associated with Clinical Course in Recurrent Respiratory Papillomatosis

Background: RRP is a devastating disease in which papillomas in the airway cause hoarseness and breathing difficulty. The disease is caused by human papillomavirus (HPV), 6 or 11 and is very variable. Patients undergo multiple surgeries to maintain a patent airway and in order to communicate vocally. Several small studies have been published in which most have noted that HPV 11 is associated with a more aggressive course. Methodology/Principal Findings: Papilloma biopsies were taken from patients undergoing surgical treatment of RRP and were subjected to HPV typing. 118 patients with juvenile-onset RRP with a least 1 year of clinical data and infected with a single HPV type were analyzed. HPV 11 was encountered in 40% of the patients. By our definition, most of the patients in the sample (81%) had run an aggressive course. The odds of a patient with HPV 11 running an aggressive course were 3.9 times higher that that of patients with HPV 6 (Fisher's exact p=0.017). However, clinical course was more closely associated with age of the patient (at diagnosis and at the time of the current surgery) than with HPV type. Patients with HPV 11 were diagnosed at a younger age (2.4y) than were those with HPV 6 (3.4y) (p=0.014). Both by multiple linear regression and by multiple logistics regression HPV type was only weakly associated with metrics of disease course when simultaneously accounting for age. Conclusions/Significance Abstract: The course of RRP is variable and a quarter of the variability can be accounted for by the age of the patient. HPV 11 is more closely associated with a younger age at diagnosis than it is associated with an aggressive clinical course. These data suggest that there are factors other than HPV type and age of the patient that determine disease course. © 2008 Buchinsky et al