Nowadays the world´s demand for natural resources is more pressing than ever before. The good quality of the water and it’s enough quantity, the provision of energy sources and food is a very important and difficult issue. This challenge could be done by ensuring a better management of the mentioned resources. Strengthening synergies and reducing trade-offs among the sectors is possible by applying a Nexus approach. This article aims to assets the land cover, land use and water quality in the upper and middle catchment of the Osam River (municipalities of Troyan and Lovech) for the period 2012-2019. Land use and land cover is a key factor in relation to water quality characteristics. The emphasis is on acquiring new knowledge through spatio-temporal analysis of the problem. To assess the river water quality this study considers the following parameters: pH, dissolved oxygen (DO), electric conductivity (EC), ammonia (N-NH4), nitrates (N-NO3), nitrites (N-NO2), phosphates (P-ortho-PO4), biological oxygen demand (BOD5). To identify the land use/cover in the region was based on GIS, digital topographic and thematic maps, Corine Land Cover data, high-resolution satellite imagery (Google Earth), digital elevation model, statistics and field studies. The obtained results are a good basis for popularizing the Nexus paradigm at different scales (i.e., local, regional, national, European and beyond) including planning and elaboration of the necessary policies for sustainable management of both land use and river waters in terms of their quality.

As research regarding the production and optimization of geopolymer materials is constantly increasing and is fundamentally motivated by the need, identified both in the global ecological context and at national level, new materials can be developed using this type of binder. Sustainable consumption of resources, focuses on the capitalization of existing waste and prevention of generating new ones, therefore adopting the Sustainable Development principles. The increase in the utilization of sand from rivers for various construction purposes, which also disturbs the environment can be considered another damaging factor for the environment. Recycling of garnets and their use as replacement for sand aggregates could provide an ecological solution for the production of the alkali-activated fly ash-based geopolymer binders. The aim of this paper is to present preliminary results regarding the use of spent garnet as replacement for sand aggregates in the production of alkali-activated fly ash-based geopolymer binders using Romanian local raw materials and to study its influence on the mechanical performances of the binder.

Hot Air Solder Leveling (HASL) is one of the most commonly used surface finishes in the industry. HASL is also one of the least expensive types of PCB surface finishes available. This study aims to examine the influence on the solder joint microstructure of dipping time and solder temperature. During soldering process, the temperature that used were 300°C and 400°C. The dipping time was split into three batches which is 20s, 60s, and 100s. The Sn-0.7Cu-0.05Ni solder alloy was used in this analysis to shape the solder coating microstructure. In this analysis, an Optical Microscope (OM) was used to determine the microstructure of the shape of the solder coating microstructure. As dipping time and dipping speed increased, the interfacial IMC thickness was found to increase, grown up and getting thicker. This outcome results can be used as the basis in order to improve the solder joint properties.

The scientific article is devoted to the study of modern technologies for restoring the internal surfaces of critical parts of the structural elements of oil and gas pumps. By the method of critical analysis of defects, it was found that paraffin deposits and mechanical impurities are in the list of the main complicating factors leading to abrasive wear of the working surface of the parts being contacted. Asphalt-resin-paraffin deposits together with mechanical impurities are distributed unevenly, for example, along the diameter of the cylinder of the injection column, narrowing the passage section of the rod in different stroke length intervals. This phenomenon causes the rod to deviate from the design axis of the trajectory of movement and forms sections of the cylinder working under shock loads with maximum wear. Therefore, it is necessary to restore the degraded surface in places where maximum dynamic loads are applied. The patent search method and the evaluation of the claims allowed us to establish that the generally accepted methods of restoring internal surfaces are reduced to nitriding and chrome plating. Due to known technological shortcomings, these methods are limited in application, and it is impossible to restore the phase structure by these methods. To solve the technological problem of restoring the structure and modifying the inner surface of a small cylinder diameter, it is proposed to apply a coating with a ceramic protective layer based on nickel alloys of the carbide class, which has high hardness and inert properties. To restore the surface of worn parts in conditions of a limited coordinate space of long-dimensional elements of the RDP structure (pump and compressor pipes, a pair of cylinder-plunger and others), the authors propose a promising laser spraying.

Adsorption procedure have been studies and found to be an effective, easy, and low-cost approach for removing heavy metals from aqueous solution when compared to other methods and technologies. Porous geopolymer will be made by combining aluminosilicate mineral with an alkaline activation solution to be utilized as an adsorbent. This review focuses on the current development in heavy metal removal material. This work also summarize the crucial factors (such as solid-to-liquid ratio, foaming agent ratio, sintering temperatures, and adsorbent dosage) influenced the properties (pore formation, microstructure, chemical bonding, and phase analysis) of kaolin-based geopolymer were highlighted. This review manifests the remarkable potential of kaolin-based geopolymer in high-added value applications.

The current work focuses on the extraction of gold using alpha-cyclodextrin (a-CD) from the Kimpese quarry in the Democratic Republic of the Congo, through an environmentally friendly gold process as an alternative to the amalgamation process. The ore was sampled and characterized using atomic absorption spectroscopy (AAS) prior to the experiments, and the analysis revealed 0.08% of gold. The ore was then leached with modified aqua regia (MAR). Time, HBr concentration, pH, and stirring speed were all varied during leaching to highlight the parameters that influence the leaching yield. The optimum conditions were determined using analysis of variance (ANOVA) and response surface methodology (RSM), implying time, HBr concentration, pH, and stirring speed of 6 hours, 80g/l, 1, and 800rpm, respectively, and a leaching percentage of 98.6928%. Following leaching, neutralization tests with potassium hydroxide (KOH) were performed by varying the following parameters: time, KOH concentration, and pH. The following factors were varied in the extraction tests after neutralization: time, a-CD concentration, pH. The optimal parameters were as follows: time of 30 minutes, a-CD concentration of 8.8639g/l, and pH of 6, with yield of 89.7350%. This method of recovering gold from ore using a-CD is inexpensive and does not harm the environment.