Electrochemical and wetting behavior of as-cast Sn-Zn-Sb lead free solders alloys

Ternary alloys SnZn12Sb8, SnZn10Sb10, SnZn8Sb12, SnZn6Sb14, and SnZn2Sb18 were prepared by induction melting. Electrochemical behavior and wetting (contact angle) of prepared as-cast samples were investigated using open circuit potential measurement and sessile drop technique. The results of electrochemical investigation show that open-circuit potential, few seconds after immersing of electrodes, shifts toward more negative values, indicating a relatively smaller rate of dissolution during the spontaneous dissolution process under the curentless conditions. After that period, the values of potential tend to be constant with time. It was found that all investigated alloys have poor wettability on copper substrate and the contact angle values decrease with increasing superheat temperature

SIMULATION OF WINTER WHEAT WATER BALANCE WITH CROPWAT AND ISAREG MODELS

This paper presents the results of water balance simulations on winter wheat production in the area around Bijelo Polje. Winter wheat production over three years and on two soil types has been simulated with the CROPWAT and ISAREG models. The simulated results have proved variations between the two models and the measured yield. Crop evapotranspiration ranges between 304.5 to 463.3 mm. The relative yield obtained after the simulations is very similar to the relative yield obtained on a measured basis, except in the 2008/2009 season. Net irrigation requirements (NIR) to obtain the maximum yield are higher at 49-116 mm in the simulations with the CROPWAT model. The total NIR to maximize yield ranges between 84-300 mm depending on the season and model. Water use efficiency ranges from 0.82 to 1.28 kg/m3. The obtained results verified both models as good tools for determining winter wheat water balance and indicated that winter wheat yields could be improved with irrigation

Simulation of Silage-Maize Water Balance with CROPWAT and ISAREG Models

This paper presents the results of water-balance simulations in silage-corn production in the area around Bijelo Polje. Silage-maize production was simulated with CropWat and ISAREG models over three years and on two soil types. The simulated results showed a the variation between the two models and measured the difference in yield. Crop evapotranspiration over the three seasons ranged between 339.3mm and 421.8 mm. Net irrigation requirements were higher by 30-70 mm in the simulations with the CropWat model. Water-use efficiency ranged from 7.44 kg/m3 to 11.51 kg/m3. The obtained results confirmed both models as good tools in silage-maize water

Electrical and magnetic properties of multiferroic Bi5FeTi3O15 and Bi4.25La0.75Ti3FeO15 ceramic

Multifferioc materials exhibiting ferroelectric and magnetic orders simultaneously have attracted a lot of interest in recent years due to their special phenomena and potential applications in multifunctional devices [1]. One of the most frequently investigated single-phase multiferroic materials is perovskite BiFeO3 (BFO) but it shows weak ferromagnetics at room temperature due to its canted spin structure. Among the compounds, Bi5FeTi3O15 (BFT) ceramics can be regarded as a model of the Aurivillius type of ferroelectromagnetics [2]. BFT was prepared by solid state reaction methods from the constituting high purity oxides (Fe2O3, Bi2O3, TiO2 and La2O3). XRD data confirm the formation of single-phase Aurivillius compounds while SEM micrographs shows a evident decrease of grain size of La modified ceramics in comparison with pure BFT. Dielectric properties were investigated in a wide range of temperatures (300-1000 K) and frequencies (1 Hz – 1 MHz). The conductivity of sintered samples was studied, suggesting decreasing of conductivity of La modified ceramics in comparison with pure BFT. Ferroelectric and ferromagnetic measurements of both samples were also performed. An energy bandgap of 1.76 eV and 1.81 eV for BFT and BFLT ceramics, respectively was determined from UV-vis diffuse absorption spectrum

ELECTRICAL AND MAGNETIC PROPERTIES OF MULTIFERROIC Bi5FeTi3O15 AND Bi4.25La0.75Ti3FeO15 CERAMICS

Multifferioc materials exhibiting ferroelectric and magnetic orders simultaneously have attracted a lot of interest in recent years due to their special phenomena and potential applications in multifunctional devices [1]. One of the most frequently investigated single-phase multiferroic materials is perovskite BiFeO3 (BFO) but it shows weak ferromagnetics at room temperature due to its canted spin structure. Among the compounds, Bi5FeTi3O15 (BFT) ceramics can be regarded as a model of the Aurivillius type of ferroelectromagnetics. BFT was prepared by solid state reaction methods from the constituting high purity oxides (Fe2O3, Bi2O3, TiO2 and La2O3). XRD data confirm the formation of single-phase Aurivillius compounds while SEM micrographs shows a evident decrease of grain size of La modified ceramics in comparison with pure BFT. Dielectric properties were investigated in a wide range of temperatures (300-1000 K) and frequencies (1 Hz – 1 MHz). The conductivity of sintered samples was studied, suggesting decreasing of conductivity of La modified ceramics in comparison with pure BFT. Ferroelectric and ferromagnetic measurements of both samples were also performed

STRUCTURE AND CHARACTERIZATION OF (x)Ni0.7Zn0.3Fe2O4 – (1-x)BaTiO3 COMPOSITES

Multiferroic composites with formula Ni0.7Zn0.3Fe2O4 - BaTiO3 (x = 0.1, 0.3, 0.5, 0.7, 0.9) were prepared by mixing chemically obtained NZF and BT powders in the planetary mill for 24 h. NiZnFe2O4 (NZF) powder was prepared by auto-combustion method starting from nickel, zinc and iron nitrates. Barium titanate (BT) powder was prepared with the same method. The optimization of sintering process was performed. One series of powders were pressed and sintered at 1170 °C, while the others were sintered at 1120 °C. X-ray measurements confirmed the presence of NZF, BT phases and the traces of barium ferrite phase. The microstructures of the ceramics show (Fig. 1.) the formation of grains with different shape and size. The formation of polygonal (NZF grains), rounded (BT grains) and plate like grains (barium ferrite phase) was noticed. The magnetic analyses showed that in the composites due to existence of ferroelectric phase a dilution effect appears

PROPERTIES OF PbZr0.52Ti0.48O3 - NiZnFe2O4, CoFe2O4 MULTIFERROIC COMPOSITES OBTAINED BY AUTO-COMBUSTION SYNTHESIS

Nickel zinc ferrite (NZF), cobalt ferrite (CF) and barium titanate (BT) nanosized powders were synthesised by auto-combustion method. Multiferroic composites with the formula xPbZr0.52Ti0.48O3+(1-x)CoFe2O4 and xPbZr0.52Ti0.48O3+(1-x)Ni0.7Zn0.3Fe2O4 (x=0.8 and 0.9) were prepared from nickel zinc ferrite, cobalt ferrite and barium titanate powders by mixing in planetary ball mill for 24 h. Pellets were sintered at different temperatures in order to obtain dense, two phased composites. XRD data indicated the formation of well crystallized structure of PZT and NZF/CF phase in the composite ceramics. SEM micrographs revealed a uniform grain distribution of both phases without any secondary phases. Magnetic measurements of all sintered composites were carried out and presented in Figure 1. All the composite samples exhibit typical ferromagnetic hysteresis loop, indicating the presence of the order magnetic structure. Saturation magnetization moment decreases with increasing PZT content, because of non-magnetic PZT phas

PZT-NICKEL FERRITE AND PZT-COBALT FERRITE COMPARATIVE STUDY: STRUCTURE, DIELECTRIC, FERROELECTRIC AND MAGNETIC PROPERTIES OF COMPOSITE CERAMICS

Multiferroic (MF) materials with simultaneous magnetic and electric long range order and occasionally, mutual magnetoelectric (ME) coupling, have recently attracted considerable interest. These compounds present opportunities for potential applications in information storage, the emerging field of spintronics, sensors, and multistate memory devices [1]. The ME phenomenon is observed in both single- phase as well as composite materials. The challenge in preparing such materials is to find equilibrium ferroelectric and magnetic structures preserving both properties close to the room temperature [2]. The individual phases (Ni0.7Zn0.3Fe2O4, CoFe2O4 and PbZr0.52Ti0.48O3) were prepared by citrate-nitrate combustion reaction method. Composites were prepared by mixing and homogenizing PZT and NZF/CF powders in a planetary ball mill in the ratio: (x) PZT + (1-x) CF/NZF (x = 0.8 and 0.9). XRD diagrams of a sintered composite confirm the presence of only two phases, ferroelectric PZT phase and ferrite phase. SEM analysis revealed a uniform grain arrangement of both phases. Similar values of saturation magnetization (Ms) for both types of composites were observed. Ms increases with increasing magnetic phase, as it was expected. Significantly higher values of coercive field (HC) can be seen in the composite with a cobalt-ferrite, which belongs to the group of hard ferrite unlike NZF which is soft ferrite and characterized by low values of coercive field. The ferroelectric properties of all ceramic composites were also studied

Biofilm Adhesion and Micromorphology Analysis after Professional Oral Hygiene Procedures on CAD/CAM Milled and Veneered Zirconia Restorations: In Vitro Study

Objective: The purpose of this study was to evaluate the surface texture and biofilm adhesion of veneered or CAD/CAM milled zirconia (partially stabilized with yttrium) after professional oral hygiene procedures. The samples (4 × 4 mm, thickness 2 mm; n  =  72) were separated from zirconia blanks (3Y-TZP-LA). One group was veenered with ceramics, and the other group of samples was CAD/CAM milled. Each group had two subgroups: polished and glazed. The samples were subjected to simulated strokes of professional brushing using abrasive paste and ultrasonic scaling. The parameters of surface micromorphology and receptivity to biofilm were calculated before and after simulating the given methods of the professional maintenance of oral hygiene. Scanning electron microscopy (SEM) was used to evaluate zirconia surface properties. Microbial (bacterial/fungal) species (Staphylococcus aureus, Streptococcus sanguinis and Candida albicans) were used and cultured on respective sterilized zirconia surfaces. Colony-forming unit (CFU) counts were used to quantify the amount of biofilm formation on zirconia samples surfaces. Results: The SEM analysis showed the greatest change in surface microtopography after the use of ultrasonic scaling on glazed zirconia samples. Less formation of colonies on the surfaces of CAD/CAM milled zirconia restorations was observed. Conclusion: Routine methods of oral hygiene professional maintenance can damage the surfaces of glazed zirconia restorations

GEO-6 assessment for the pan-European region

Through this assessment, the authors and the United Nations Environment Programme (UNEP) secretariat are providing an objective evaluation and analysis of the pan-European environment designed to support environmental decision-making at multiple scales. In this assessment, the judgement of experts is applied to existing knowledge to provide scientifically credible answers to policy-relevant questions. These questions include, but are not limited to the following:• What is happening to the environment in the pan-European region and why?• What are the consequences for the environment and the human population in the pan-European region?• What is being done and how effective is it?• What are the prospects for the environment in the future?• What actions could be taken to achieve a more sustainable future?<br/