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Patients with total atrioventricular block are of particular interest and prone to severe prognosis unless treated with emergency cardiac pacing. We evaluated different types of leads and their impact on the myocardium, according to the fixation type and pacing method.. A pacemaker patient has a different depolarization pattern and a single chamber pacemaker, has by definition, an intracardiac desynchronization and a different electro-mechanical coupling activity. The presence of late potentials is an independent prognosis factor for cardiac death and electrical vulnerability, especially after myocardial infarction(MI). Late potentials recorded as magnitude vector are the expresion of late depolarization of the surrounding tissue and represent the morfological substrate for reentry. Thus, the incidence of late potentials after pacemaker implant, represents the expresion of electrical vulnerability of the stimulated right ventricular myocardium. In order to deeply study the parameters of magnitude vectors, we noticed the appearance of late potentials during the transitory stimulation in acute atrioventricular block and a restoration of vector normal parameters, after conduction recovery and sinus rhythm conversion.

A bone defect with standard dimensions and localization is produced. Inside this defect a polymer (collagen sponge) impregnated with growing factors, i. e. bone morphogenetic protein – BMP, is introduced. For the witness lot, the same defect is produced, in which the same polymer is introduced, but without any growing factors. It is found that the growing factor not only remains at the initial site, but also has effect on the bone regeneration process. A mathematical model is constructed using a field theory of multifractal type based on the spontaneous symmetry breaking mechanism to exploit such dynamics in biostructures. This mechanism contains all the informational “ingredients”: the multivalent logic based multifractal bit, the algorithm based networks through spatial cnoidal modes of oscilation, etc. In such context, the evolution of all biostructures, through a mechanism that mimics a 3D biological printer, can become operational.

Sutures are classified into non-absorbable and absorbable, and mechanical properties of these materials vary by the composition. In this study we analyze four different types of sutures used commonly in surgery: silk, nylon, polyglycolic acid (PGA) and polytetrafluoroethylene (PTFE). The materials were chosen to represent a wide range of suture material categories: absorbable and nonresorbable, monofilament and multifilament, natural and synthetic in order to assess their mechanical properties but also the bacterial adherence to each type. The objective of this study was to measure the total bacterial adherence by using real time PCR at 7 days postop and to analyze the antibacterial and mechanical properties comparatively depending on the type and composition of sutures. Tensile properties such as maximum tensile load, elongation rate, stiffness and energy absorbed before breakage were taken into consideration. Experimental determination pointed out that the average total bacterial load was lowest for PTFE and highest for silk. The results of the study are useful in choosing an appropriate suture wire according to the mechanical properties taking into account the bacterial load of the surgical site in order to aid in tissue repair.

This work presents an experiment aimed at determining the concentration of heavy metals found in the water resources of natural receivers. Heavy metals are very dangerous both for the aquatic life environment, influencing the health of the respective living beings and for the human health especially if there is an open contact between the human and the respective water source. Due to the different technological processes of the treatment plants, the wastewater, however, contains a high concentration of heavy metals, which means that those technological processes do not fully comply with the legal requirements. A good, viable solution that is being researched more and more at present is the use of types of polymeric membranes, suitably adapted in ultrafiltration processes of wastewater. Many of today`s advanced researches focus on investigating the retention of heavy metals by membranes. The purpose of this work is to determine the concentration of the main heavy metals such as Fe2+, Zn2+, Cu2+, Pb2+, Ni2+, Mn2+, etc. and other elements such as: Fluorides, Nitrites NO2-N, Phosphates PO4-P, Ammonium NH4-N etc, both before using an organic membrane of PAN from hollow fibers and after cessation of the ultrafiltration experiment to determine the % of the respective metals. can be removed after the ultrafiltration process. The results of the analyzes carried out during the experiment showed that some of the above mentioned chemical elements can be retained by more than 85 % so that a membrane of PAN can reduce the degree of pollution of the waste water, especially where the waste water is directly discharged into natural source of water. At the same time, 14 chemical elements present in the waste water were analyzed and after determining the concentration of the heavy metals after the completion of the experiment it can be confirmed that the use of polymeric membranes is and will be a viable solution for the purpose of protecting the environment and health.

A mathematical model regarding water filtration with a nanofiltration (NF) titanium dioxide ceramic membrane is presented. The experiments aimed to use the excitation-emission matrix (EEM) spectroscopy method to highlight the existence of humic acid (HA) in water, before and after the NF process. Following the established operating conditions, experiments were performed for each quantity of AH separately, leaving the installation to work at the appropriate parameters for 15 minutes. for each quantity of AH. The analyzes for EEM fluorescence were performed using the FP-8300 spectrofluorimeter. The collected samples were analyzed with Spectra Manager II software on fluorescence intensity (au - arbitrary units), with an emission wavelength (nm) between 460 and 640 nm and with an excitation wavelength (nm) between 350 and 600 nm. Following the experiments carried out, mathematical correlations were established between the parameters that influence the filtering process and the studied parameters. It is worth mentioning that as a result of the experiments carried out, a number of 20,450 values were obtained, which were used for the elaboration of mathematical models. These models, for sets of values of the order of tens of thousands, verified both from the point of view of the real values and from the point of view of the regression coefficients (coefficients close to the value 1), demonstrate the quantity and the very good quality of the experimental data, respectively of the measured and calculated sizes. In order to validate the generated equations, they were subjected to checks, the difference being obtained between the value obtained by experimental means and the value obtained within the mathematical model. And the value of the resulting relative error, gives information on the accuracy (truth) of the mathematical model, so that it can be extended to other experiences. It turns out that this method cannot quantitatively determine the value of a parameter, but it can highlight the presence and differences between two samples.

The clinical success of any indirect prosthodontic restoration is strongly related, among other numerous factors, to the fixing procedure. The technological deficiencies into the inlay cementation lead to defects, either in depth or on surface, which often cause failures. The longevity of inlays depends, to a large extent, on the quality of the dental-prosthetic joint. This marginal adaptation is influenced by the thickness and the type of the luting cement. The aim of this study is a comparative analysis on the behavior of the luting cement for composite resin and ceramic inlays in two different solutions: ANFOR-type artificial saliva and a 20% citric acid solution. Fixing composites are the material of choice for works with high aesthetic potential, our study revealing that their depreciation and alteration is reduced, even in aggressive environments. Cementation seems to be the most critical step, and its long-term success relies on adherence to the clinical protocols.

Iron-based amorphous alloys are characterized by so-called soft magnetic properties. Unfortunately, the geometry of iron-based amorphous materials significantly limits the applicability of these materials. One way to expand the use of these materials is to make composites based on them. As part of this work, rapid-cooled alloys were produced using the injection casting method. On their basis, magnetic composites with the addition of a non-magnetic binder were produced. The results of the structure (XRD) and magnetic properties (VSM) tests of the produced materials are presented. The research results have shown that the decisive impact on the magnetic properties of composites is the fact of the separation of magnetic particles with a non-magnetic binder. In this case, the influence of exchange interactions is dominated by dipole interactions.

This paper is part of a larger study that aims to evaluate the biomechanical behaviour of mandibular bone and periodontal splinting systems subjected to different occlusal forces by means of electric resistive tensometry (ERT). The research was based on the following premise: the degree of bone resorption and periodontal type of splint influence the deformation of the mandibular bone. The study was conducted in two stages: first, the validation of the mandibular dental arch model, which is the subject of the present article, and second, the evaluation of mandibular bone strain in case of different types of bone loss and periodontal splints, which is the subject of a second article.

Polyurethane foam wastes is one of the environmental problems for which are not still the efficient solutions of valorization. This paper presents the possibility of recovering polyurethane foam waste by obtaining some new materials with sound absorption properties. The polyurethane foam wastes were ground and mixed, in proportion of 0, 3, 5, 7 and 12 wt%, with bicomponent polyurethane foam as a binder, resulting 5 new materials. The sound-absorbing properties of the new materials have been determined and it can be observed that the sound-absorbing properties of rigid polyurethane foam with closed pores can be improved by adding polyurethane foam waste to its structure. In addition, the mechanical properties and thermal conductivity of the new materials were studied.

The fragility fracture fixation confronts with the major problem of implant loosening due to the altered bone structure. Techniques used to fragility fracture stabilization includes metals devices, cements or adhesives. Different types of cements and adhesive can be obtained by chemical manipulation in order to provide a more efficient transition between the metal surface and the real bone. Thus, by selecting the appropriate chemical composition and ration between the components, synthetic cement and adhesive can provide a proper interface that ensure a perfect cohesion between the implant material and the natural bone. Most of the studies point the benefit of these synthetic materials in improving screw fixation strength. That is why, currently, the synthetic materials used in prosthesis are improved by associating with natural components of the bone, such as hydroxyapatite. For osteoporosis, which is characterized by demineralization, the association of the implanted material with hydroxyapatite is expected to be a suited solution for bone matrix regeneration after implantation. The aim of the current study was to assess the mechanical properties of orthopedic screws coated with a new polyurethane acrylate polymer containing hydroxyapatite in order to improve the stability of the screw for the subsequent fixation of the fragility fracture. To test the efficiency of the new hydroxyapatite containing polymer, the mechanical behavior of the coated screws was evaluated. Our data show that the augmented screw can be obtained by incorporating lower hydroxyapatite concentrations.