Pulsed LASER-(micro)TIG hybrid welding: Process characteristics

A variant from the laser-arc hybrid welding process family which combines a pulsed laser process (Nd:YAG) and a pulsed (micro)TIG welding process is described.For studying the present variant process’ characteristics experimental work was carried out using video data acquisition and thermal imaging. In this paper, the characteristics of the present hybrid welding process variant and the influence of TIG welding parameters onto the process stability and the welding process result are presented. The experimental work revealed that the transient hybrid coupling phenomena, which is specific to the present hybrid process variant, has an important influence onto the process stability and the processing result. At the same time a strong interaction between the controlled process parameters was observed and that rather small changes to the process parameters values have a strong effect onto the process stability. The recommended TIG frequency domain for using as well as the variant which provides the best option to attenuate the penetration variation, specific to pulsed laser welding, was determined. The TIG frequency values which seem to lead to a stable welding process are of the same order as the ones used for laser pulse repetition rates. The variant that leads to an attenuation of the penetration is pulsed TIG-laser (with TIG as the leading process).     

Hybrid nanostructured coating for increased resistance of prosthetic devices to staphylococcal colonization

Prosthetic medical device-associated infections are responsible for significant morbidity and mortality rates. Novel improved materials and surfaces exhibiting inappropriate conditions for microbial development are urgently required in the medical environment. This study reveals the benefit of using natural Mentha piperita essential oil, combined with a 5 nm core/shell nanosystem-improved surface exhibiting anti-adherence and antibiofilm properties. This strategy reveals a dual role of the nano-oil system; on one hand, inhibiting bacterial adherence and, on the other hand, exhibiting bactericidal effect, the core/shell nanosystem is acting as a controlled releasing machine for the essential oil. Our results demonstrate that this dual nanobiosystem is very efficient also for inhibiting biofilm formation, being a good candidate for the design of novel material surfaces used for prosthetic devices.     

Biohybrid Nanostructured Iron Oxide Nanoparticles and Satureja hortensis to Prevent Fungal Biofilm Development

Cutaneous wounds are often superinfected during the healing process and this leads to prolonged convalescence and discomfort. Usage of suitable wound dressings is very important for an appropriate wound care leading to a correct healing. The aim of this study was to demonstrate the influence of a nano-coated wound dressing (WD) on Candida albicans colonization rate and biofilm formation. The modified WD was achieved by submerging the dressing pieces into a nanofluid composed of functionalized magnetite nanoparticles and Satureja hortensis (SO) essential oil (EO). Chemical composition of the EO was established by GC-MS. The fabricated nanostructure was characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Differential Thermal Analysis (DTA) and Fourier Transform-Infrared Spectroscopy (FT-IR). The analysis of the colonized surfaces using (Scanning Electron Microscopy) SEM revealed that C. albicans adherence and subsequent biofilm development are strongly inhibited on the surface of wound dressing fibers coated with the obtained nanofluid, comparing with regular uncoated materials. The results were also confirmed by the assay of the viable fungal cells embedded in the biofilm. Our data demonstrate that the obtained phytonanocoating improve the resistance of wound dressing surface to C. albicans colonization, which is often an etiological cause of local infections, impairing the appropriate wound healing.     

EFFECT OF HETEROATOMS ON PARTITIONING OF π-ELECTRONS IN RINGS OF CATAFUSENES

An earlier proposed method for assessing the π-electron content (EC) of rings of heteroatom–containing polycyclic conjugated molecules [Balaban et al., Polycyclic Aromatic Compounds/27 (2007) 51] is modified so that the effects of heteroatoms become additive. By means of this, relatively simple rules for the changes of the EC-values could be formulated in the case of catafusenes.     

Amphiphile polydimethylsiloxane‐based networks reinforced with in situ generated silica

Polydimethylsiloxanes, side functionalized in different degrees with chloromethyl groups, were reacted with 4,4′‐bipyridyl and crosslinking occurred by the formation of ionic (bipyridinium) groups. The reactions were carried out in a silica sol–gel system, and thus, two networks were generated simultaneously: amphiphile siloxane‐organic and silica networks. The samples, processed as films, were characterized by Fourier transform infrared spectroscopy to verify the occurrence of the crosslinking reactions. Different techniques were also used to evaluate the properties: differential scanning calorimetry for emphasizing the transitions, scanning electron microscopy, and atomic force microscopy for the evaluation of the morphology and surface topography. The modification of the film surface topography, which depends on the solvent polarity, was also emphasized. The sorption capacities of the water vapors and of liquid solvents (water and chloroform) were investigated, and the obtained values proved to be a function of the polar group's content. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

A Coalgebraic Semantics for Epistemic Programs

This paper gives a fresh look at my previous work on “epistemic actions” and information updates in distributed systems, from a coalgebraic perspective. I show that the “relational” semantics of epistemic programs, given in [BMS2] in terms of epistemic updates, can be understood in terms of functors on the category of coalgebras and natural transformations associated to them. Then, I introduce a new, alternative, more refined semantics for epistemic programs: programs as “epistemic coalgebras”. I argue for the advantages of this second semantics, from a semantic, heuristic, syntactical and proof-theoretic point of view. Finally, as a step towards a generalization, I show these concepts make sense for other functors, and that apparently unrelated concepts, such as Bayesian belief updates and process transformations, can be seen to arise in the same way as our “epistemic actions”.     

Promising Therapies for Atrial Fibrillation and Ventricular Tachycardia

Sudden cardiac death due to arrhythmias, such as atrial fibrillation or ventricular tachycardia, account for 15–20% of all deaths. Myocardial infarction increases the burden of atrial fibrillation and ventricular tachycardia by structural and electrical remodeling of the heart. The current management of new-onset atrial fibrillation includes electric cardioversion with very high conversion rates and pharmacologic cardioversion, with less a than 50% conversion rate. If atrial fibrillation cannot be converted, the focus becomes the control of the symptoms ensuring a constant rhythm and rate control, without considering other contributory factors such as autonomic imbalance. Recently, a huge success was obtained by developing ablation techniques or addressing the vagal nerve stimulation. On the other hand, ventricular tachycardia is more sensitive to drug therapies. However, in cases of non-responsiveness to drugs, the usual therapeutic choice is represented by stereotactic ablative therapy or catheter ablation. This review focuses on these newly developed strategies for treatment of arrhythmias in clinical practice, specifically on vernakalant and low-level tragus stimulation for atrial fibrillation and stereotactic ablative therapy for drug-refractory ventricular tachycardia. These therapies are important for the significant improvement of the management of atrial fibrillation and ventricular tachycardia, providing: (1) a safer profile than current therapies, (2) higher success rate than current solutions, (3) low cost of delivery.     

Current and Emerging Approaches for Spine Tumor Treatment

Spine tumors represent a significant social and medical problem, affecting the quality of life of thousands of patients and imposing a burden on healthcare systems worldwide. Encompassing a wide range of diseases, spine tumors require prompt multidisciplinary treatment strategies, being mainly approached through chemotherapy, radiotherapy, and surgical interventions, either alone or in various combinations. However, these conventional tactics exhibit a series of drawbacks (e.g., multidrug resistance, tumor recurrence, systemic adverse effects, invasiveness, formation of large bone defects) which limit their application and efficacy. Therefore, recent research focused on finding better treatment alternatives by utilizing modern technologies to overcome the challenges associated with conventional treatments. In this context, the present paper aims to describe the types of spine tumors and the most common current treatment alternatives, further detailing the recent developments in anticancer nanoformulations, personalized implants, and enhanced surgical techniques.