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In this study, strontium is used as an alloying element for improving the pitting resistance of Mg-5Al-4Sn based alloys in an alkaline solution. Potentiodynamic polarization measurements suggest that the addition of strontium increases the robustness of the pitting resistance as a result of the higher pitting potential and wider range of passive potential. Electrochemical impedance spectroscopy (EIS) confirms the formation of a solid passive film on the alloy surface due to a significant increase in the passive film and the charge transfer resistance, as well as lower film and double layer constant phase element magnitude values. Additionally, the potentiostatic polarisation results also show a lower passive current density and passive film stability, resulting in an increase in the breakdown time when the amount of strontium added to the alloy increases from 0.0 to 1.0 wt%. Furthermore, the scanning electron microscopy results indicate that insignificant corrosion is observed on alloy specimens containing strontium, whereas there is fierce corrosion on alloy based surfaces. This robust corrosion resistance could be attributed to the α-grain reduction and refined precipitates at the alloy grain boundaries, resulting in promoted formation of the passive film which is formed from a mixture of magnesium, aluminum and tin oxides/hydroxides, as confirmed by the X-ray photoelectron spectroscopy results.

Reducing the costs of wastewater treatment plants in the food industry is a necessity. Thus, it is necessary to find solutions to make their operation more efficient. The use of biogas obtained in the production process is a variant that leads to the increase of the profit at the whole plant level. This is how the Balance Scorecard model was used. The use of this model was based on non-financial indicators. These were: biogas quality and wastewater indicators from the UASB reactor that ensures biogas quality.

Since the efficient agricultural sector is one of the most important drivers of country's economic development, the main objective of this paper was to examine relative technical efficiency of agricultural production in 25 Serbian districts using two-stage data envelopment analysis. Results of this research indicate that the efficiency score values lie between 70% and 100%, therefore it can be concluded that the agricultural sector of Serbia performs at a high level of efficiency, with the average efficiency score of 90%. The lowland region of Vojvodina is characterized with the highest efficiency scores, while districts in the southeastern part of Serbia have the lowest efficiency score values. Furthermore, the Tobit regression model was applied that one may examine the drivers of technical efficiency scores. The results show the significance of agricultural training among farm managers, land irrigation and age of farm holders in altering agricultural efficiency among Serbian districts.

Leaf extracts are widely used to mitigate the steel corrosion in an acidic environment. This work focuses on the effective acidic inhibition of a Piper Betle leaf extract (PBLE) that can be added to a green corrosion inhibitor system, giving a high corrosion inhibition performance of steel in a 0.1 M HCl solution. The relatively destructive potentiodynamic (PD) and potentiostatic (PS) polarizations combined with some non-destructive electrochemical techniques, including linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS), perform the high corrosion inhibition likely a mixed behavior for steel in investigated solution. Surface analysis demonstrates that the nano porous film formation is PBLE concentration dependent. The results indicate that the inhibition efficiency is increased by the addition of PBLE at a concentration up to 2000 ppm due to a compact, robust, and uniform protective film formation. Moreover, an increase in PBLE concentration up to 2500 ppm decreased the inhibition efficiency due to a decrease of the PBLE species’ activity in the solution that significantly affects the nano porous film formation. This work suggests a new inhibitor that can be added to a green corrosion inhibitor system for delivering high corrosion resistance of steel through a controlled surface treatment.

Access to education outside applicants' country of origin has increased in recent years for some countries, but has also created numerous barriers for others. Thus, for certain specializations, age groups have become representative. Countries with lower taxes and engineering specialties sought on the labor market have applicants from the age group 25-34 years. The other developed countries have a higher proportion of older students in MA and other postgraduate studies, including doctorate. Such countries are Australia, Germany, the Netherlands. The Participation of foreign students in the education system does not take into account the traditional view. Thus, in this paper, a non-random component was developed that uses two tools as evaluation tools: state laws where the prospective student applies and proximity to the applicant's university.

Analyzing the current waste water treatment possibilities in the brewing industry, finds that an extra amount of oxygen in the system can lead to improved water quality. Also, the need to improve the anaerobic stage may be a technically and economically efficient method. Taking into account these two premises, the paper presents the results obtained by applying the two methods of treatment, and present a comparative study of the water quality before and after the improvement of the purification process.

Effective integration policies must be considered as a priority on the migration agenda of any government, regardless of whether migrants are temporarily staying or permanently settling in the country. Integration is essential for all stakeholders to benefit from migration and the contribution it brings to the security, prosperity and stability of society.Addressing the role of online socialization platforms in the mobility period knows in the literature a duality of experts' opinions. That is why the present work focuses on the advantages of socializing in the virtual environment, in the sense that these interactions facilitate the integration in the new academic environment and overcome the cultural shock, against the voices who believe that the use of these instruments favors the phenomena of loneliness, social anxiety, etc.

Manufacture of wastewater treatment technologies is an important issue due to the complexity of design parameters and performance. Biological wastewater treatment is a process in which the intensity of oxygen transfer into water is an issue that has been extensively studied but yet insufficiently resolved. The present paper aims to describe an aeration system developed by the author in the laboratory by means of non-conventional technologies, and subsequently implemented in refinery wastewater treatment plants. The aeration system takes the form of modules, which are equipped with a new type of membrane. The analysis of the system performance revealed that oxygen transfer was 62%, specific adsorption of oxygen was 37 % and the specific oxygen transfer was 7%/m. The advantages of this new system are as follows: compared to existing technologies there is a higher rate of oxygen transfer into water; longer life; there are no dead zones in the basin as a result of their location; possibility of operating on separate sections.

The development of corrosion inhibitors that could spontaneously adsorb immediately on the metal surfaces after they are damaged by electrochemical reactions would remarkably arise the improvement of cost-saving, durability and environmental impact of metals. The use of leaf materials for metal corrosion remains an important challenge due to the high corrosion protection, availability as natural materials, environmental friendly and low-cost. Herein, we report a Houttuynia cordata leaf extract as a green corrosion inhibitor that acts as a mixed type of inhibitor for steel in an aqueous 0.1 M hydrochloric acid solution. It also performs the high inhibition performance (up to 98.3% by adding 1500 ppm inhibitor), spontaneous uniform and smooth film formation of the steel surface and less corrosion attack when the H. cordata leaf extract is added to the aqueous hydrochloric acid solution. In contrast to the inhibited systems, uninhibited specimen is severely corroded at high corrosion rate, which is associated with a significant degradation of the entire steel surface. Additionally, investigation on good adhesion and thermal stability of the protective film, as well as enriched electron abundance of selected inhibitor species are performed via molecular dynamics simulation method. Furthermore, insights of corrosion, inhibition and spontaneous film formation mechanisms are also proposed and discussed in detail.

Wastewater from the oil industry treatment is very difficult to achieve in an uniform matter. Therefore, pre-treatment steps are often required in order to reduce the compounds’ elimination and to determine which treatment cannot be eliminated in the biological stage. Application of a pre-treatment process eliminates certain compounds with specific microorganisms that do not fit with the activated sludge. In this paper, the details of this solution were studied. It was established a reduction of the benzene concentration from 82.23 mg/L to 18.04 mg/L, toluene 3.08 mg/L to 1.15 mg/L, xylene at 4.1 mg/L to 3.1 mg/L and naphthalene 7.08 mg/L to 4.96 mg/L. Experiments have shown a decrease of the polycyclic aromatic hydrocarbons concentration below the limit of detection of the device.

Monitoring the quantity of the sludge resulted from domestic wastewater treatment is a current concern in Romania due to the necessity to reduce any risk. This paper discusses the results of monitoring and examination of sludge deposited temporarily in a domestic wastewater treatment plant (5000 people equivalent) from qualitative point of view, following the analysis of the physical-chemical parameters: pH, total solids, specific resistance to filtration, humidity and density. Based on data acquired during this investigation, information on groundwater quality from the sludge beds areas is available. This allowed us to make a further analysis of the risk factors associated to sludge storage.

In Romania s industrialized areas there are a large number of people, and therefore the amount of generated waste becomes important. Moreover, waste management activities have a high share in local and national administration. Prahova County had the highest national average density of 62.83 inhabitants/km2. With two major cities, Ploiesti and Campina, the composition of the urban and rural waste stored in landfill does not always respect the existing norms at national and local level. The study developed in the present paper was elaborated in order to find the alternatives and practices necessary to be implemented to reduce the landfilled municipal waste and to increase the degree of recycling. This is based on the analysis of municipal waste composition in the two areas. Based on this analysis, we proposed the construction of a sorting station to reduce the amount of recyclable waste landfilled and to minimize environmental impacts.

Desulphurization by reactive adsorption was studied on sand abrasive blasting grit/ bentonite. The adsorbent was characterized by determining the composition, adsorption isotherms, specific surface area, pore volume and average pore diameter. Adsorption experiments were performed in continuous system at 260�300oC, 25 atm and volume hourly space velocities of 1-2 h-1. The efficiency of adsorption was evaluated at desulphurization of a synthetic reaction mixture and a catalytic cracking gas oil.

The use of surfactants in the process of water separation from crude oil emulsions formed at extraction is an effective solution in the treatment of crude oil. But perfecting this technology to a higher degree of efficiency, in order to destabilize the emulsion formed, requires the determination of the parameters involved in the design and the correlation of the obtained results. This research also aims at finding optimal solutions that increase the degree of water separation from emulsions using surface-effective solutions to destabilize the emulsion layer. This research was basedon data from two wells that extract oil from Barc�u reservoir. To achieve this objective, the composition of crude oil was analyzed, the emulsion characteristics were established and the elected demulsifiers were tested. The study highlights the efficiency of destabilization up to 97.9 mass %.

Mixture metal oxide system Co-Cr were prepared by decomposition of the precursor complexes obtained from a mixture Co-Cr nitrates with tartaric acid. The samples were subsequently submitted to chemical analysis, magnetic measurements, IR spectrometry, UV-Vis, thermal analysis, XRD, EXAFS and TPR. At 600oC was identificated a solid solution of CoCr2O4 with Co3O4. With Cu-CrK-edge EXAFS the local structure of samples calcinated of 420oC and 600oC was obtained. By theirs analysis was calculated: the lengths of M-O bounds, number of coordination (N), Debye-Waller factor (A1) and x metallic cations fraction in tetrahedral structures (spinelic centers). The TPR measurements were emphasized the existence of two reduction cycles.

Hydrogenolysis of glycerol was conducted on catalyst of the type mixed oxide of Cu-Cr doped with NiO on g-Al2O3. The prepared catalyst was analyzed by XRD, IR and TPR. Catalytic tests were carried out on a laboratory plant in continuous flow system on a reactor equipped with heating mantle, at molar ratio of glycerol / hydrogen of 1/300, glycerol volume hourly space velocities 1000s-1, temperatures 200-220oC and pressures 3-5 bar. The main reaction products identified were propylene glycol and hydroxyacetone. Glycerol conversion increases with temperature and pressure on ranges of parameters studied. Selectivity to propylene glycol increases with increasing of temperature and pressure and the selectivity to hydroxyacetone decreases with increasing of temperature and pressure on the variation range of the parameters studied.