Browse Articles

In the recent years, engineered nanoparticles (NPs) such as PLGA or poly-lactic-co-glycolic acid, have raised a substantial interest due to their possible medical applications in vaccination, diagnostic imaging procedures, cancer therapy or sustained delivery of drugs. The main aim of the present work is to evaluate key oxidative stress parameters in several organs following NPs administration in an animal model. Our data shows that acute oral administration of PLGA NPs induces a change in the antioxidant status in both rat liver and spleen, but may not induce oxidative stress damage to cell structures such as lipid or protein oxidation.

One hundred micro-implants from two different manufacturers were used in the study. From each manufacturer (Link from MISTM and Yesanchor from OrlusTM) the implants were divided in 5 groups: G0 (n=10) new, unused, G1 (n=10) mini-implants inserted in pig bone and removed, ultrasonically cleaned, followed by autoclave sterilization, G2 (n=10) same insertion protocol of group 2 followed by chemical cleaning with phosphoric gel and autoclave strerilization, G3 (n=10) same insertion protocol of group 1 followed by sandblasting and autoclave sterilization, G4 (n=10) same insertion protocol of group 2 followed by cleaning with distilled water and autoclave sterilization. Maximum insertion torque was recorded and subjected to statistical testing. Our results showed significant differences of the maximum insertion torques between groups of Link mini-implant (p=0.006), and no statistical differences of the maximum insertion torques of the Yesanchor implants (p=0.33). Significant differences (p[0.001) were also recorded between the groups of the two types of minii-mplants when compared. Our findings showed that brand-specific differences in maximum insertion torque exist between the two types of mini-implants.

The activity of using membrane technology has developed fast in the treatment of wastewater, drinking water and process water production. The main challenges in membrane filtration are fouling reduction, permeability increase and high efficiency in retention. The best example of membrane enhancement is increasing hydrophilicity. Nanoparticles have been proven that their presence in the membrane matrix increases the water affinity significantly. Although the zinc oxide nanoparticles have a positive effect over the membrane performance, the influence of zinc oxide (ZnO) nanoparticle size has not been studied enough. Two sizes of nanoparticle of ZnO and three concentrations were used for the preparation of composite polysulfone ultrafiltration membranes. The effects of the ZnO nanoparticles in the membrane matrix on the permeation properties, flux stability and retention were tested. SEM, EDX, porosity and contact angle measurement were conducted in this article, also. The experimental results indicated that ZnO-PSf composite membranes exhibits significant differences in the membrane properties due to nanoparticle addition and regardless of their size it leads to an increase in hydrophilicity, flux, permeability, retention and porosity. Decreasing the nanoparticle size leads to an increase in membrane performance.

There is limited data of short-term outcomes comparing press-fit bipolar and cemented total hip replacements in patients with femoral neck fractures. We therefore aimed to compare the perioperative incidents and immediate outcomes between press-fit stem bipolar head hemiarthroplasty and cemented total hip replacement in elderly patients with displaced femoral neck fractures. We reviewed prospectively collected data from 115 consecutive patients over 12 months. There were 21 cemented total hip replacements and 33 bipolar head press-fit stem hemiarthroplasties, with a male to female ratio of 1:1.84 and an average follow-up of 9.9 months (range 3-15). There were no differences between the two groups with respect to age (mean 77.4 years old), cortical index (0.77/ 0.82, p=0.087), hospitalization (17.7/ 16.7 days, p=0.59), bleeding, blood transfusions (14.3/ 18.2%, p=1.00) and Barthel index preoperatively, at discharge and 3 months (5.67/ 5.48, p=0.62; 10.57/ 10.47, p=0.89; 13.81/ 13.28, p=0.47). For all 54 patients the hemoglobin dropped from 13 to 11.2 g/dL after surgery without difference between implants. The mean duration of surgery was 21minutes (p[0.01) shorter for the press-fit hemiarthroplasty group compared to cemented total hip replacements. Our findings show comparable blood loss and functional outcomes with press-fit bipolar hemiarthroplasty and cemented total hip replacements for treating displaced femoral neck fractures in the elderly. Both were safe and allowed early recovery, with the only significant difference being the longer duration of surgery for the total arthroplasty.

The fixed mixed prosthetic restorations (FMPRs) are often manufactured in dentistry. Fixed prosthetic restorations mixed (RPFM) are often used in dentistry. The aim of the study was the presentation of the deficiency and the differences arising between FMPRs with metallic framework plated with two types of dental resins, currently used frequently in Romania, Superpont C + B (Spofadental, Czech Republic) and Royaldent (Palatine Foggyart, Hungary). We have achieved at 102 patients, 132 FMPRs coated with Superpont C+B and Royaldent resins. Patients were divided into two equal groups according to dental polymer used for coating. Long-term study was conducted by biannual monitoring, over three years. The results of the study showed that both resins degrades over time, from the point of view of their physical appearance and their aesthetics, and induced the apparition of gingival inflammation, but restorations coated with Royaldent resin showed less irritation of the gingival tissues.

The paper presents the experiments performed in the laboratory and the results obtained on friction and wear behaviour of the composite materials for the manufacture of brake shoes used for driving and towed rolling stock. The tribological research of these samples made of composite material with organic components aimed to determine the influence of certain material factors and operating regime parameters on the tribological properties of the tested samples. The brake shoes made of composite materials oneusesto replace the conventional cast iron brake shoes, to reduce the noise. The future research will focus on finding composite materials with superior properties compared to the currently used ones, and lower costs.

This paper analyses the influence of processing temperatures of acrylonitrile butadiene styrene (ABS), polyamide 6.6 (PA 6.6) and polyoxymethylene (POM) on some electrical properties when injecting items used in the automotive industry. The ABS specimens were made at the following injection temperatures: 220, 230, 240 and 250°C. The PA 6.6 specimens were made at the following injection temperatures: 280, 290, 300, 310 and 320°C. The POM specimens were made at the following injection temperatures: 180, 190, 200, and 210°C. The determination of electrical properties were carried out using the methods for determining the relative permittivity and the dielectric dissipation factor using zero method with Schering bridge. It was found in the three polymers analysed that the temperature rise processing by injection leads to insignificant changes in relative permittivity (er) and dielectric dissipation factor (tgd).

Testing of fire safety is based on the premise that a band should not be a fire, it would be hard to ignite and if was ignited by an external source of fire should not flame retardant. While fire resistance specifications vary from country to country, formulated to meet any fire performance specifications in the world. Tests on conveyors to assess their compliance with fire safety standards are: Drum friction test: The danger associated with a stalled belt and a driven rotating drum or pulley resulting in frictional heat build up. Laboratory flame test: The possibility of igniting the considerable mass of a conveyor belt with a relatively small ignition source. Gallery fire test: The possibility of a belt, ignited from a larger ignition source, spreading the fire to other areas (often referred to as fire propagation). Electrical resistance test: The possible build-up and subsequent discharge of static electrical charge on moving conveyors.

In this research, the impact behavior of hybrid composite materials subjected to low-velocity impact using the drop-weight installation was investigated. For this study were manufactured eight hybrid materials. All the materials were tested to 90J impact energy. The effect of fabric types used in outer layers on impact performance was studied. The impact characteristics of hybrid materials with G1 glass fabric sheets were compared with those of hybrid materials with G2 glass fabric sheets. The damage surfaces of hybrid laminates were examined by visual investigation. The results obtained showed that the using of G2 glass fabric in structure of hybrid materials improved considerable the impact characteristics.

Our study aimed to identify inorganic elements and bacterial load on the inner surface of the CPAP masks and tubing using scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) and microbiological surface analysis. By SEM were identified structures similar to Staphylococcus and Candida types. When completed by EDX were identified Cl, K, Ca, O, Ti, Na, Mg, Al, Si, S, Cl. Microbiological analysis identified Staphylococcus epidermidis (5000 CFU/mL), Staphylococcus hominis (8600 CFU/mL), and Staphylococcus haemolyticus (6500 CFU/mL). The presence of microbiological and inorganic structures raises concerns on the risk of their inhalation into the airways.