Gypsum polymer materials in construction

The modern level of technological development involves the use of traditional materials modified with additives of various types and functional purposes, as well as composite materials allowing to obtain a product with improved properties. Expanding the area of application of products based on gypsum for facade systems involves the creation of weather-resistant, and, first of all, waterproof materials based on gypsum polymers. The purpose of the experiment, the results of which are presented in the article, was to assess the possibility of using polycondensation polymers as a component of gypsum polymer, to model the properties of the material and to evaluate its characteristics as a result of climatic and humidity influences. The modeling and optimization of gypsum polymer properties were based on statistical methods as well as methods of mathematical analysis of functions of several variables. The assessment of the water resistance of gypsum polymer samples was carried out under test conditions in an open reservoir with an almost unlimited reaction capacity of the medium. The weather resistance was checked according to the results of tests in a climatic chamber. Experiments have shown that the strength of samples with 20% modified melamine-formaldehyde resin in compression and in bending for 80 days of storage in air increases by 30% and 25%, respectively. The compressive strength is 60 MPa, and the flexural strength is 12 MPa. Gypsum polymer has high frost resistance up to 150 cycles of alternate freezing and thawing. The result of the research was the confirmation of the possibility of using polycondensation resins and the foundations of the method for selecting the composition of the gypsum polymer were developed. The results obtained can be used in the development of the technology of gypsum polymer products, and, in particular, piece products (building cladding tiles).

Metal Tungstate Based Nanocomposites for Environmental Applications: Photocatalysis Mini-Review

Photocatalysis is viewed as perhaps the best-progressed treatment measures in eliminating numerous dangerous natural toxins from wastewater. It enjoys numerous benefits, however some downsides are: (i) Fast photogenerated electron–hole recombination productivity, (ii) they restricted noticeable light reaction capacity, (iii) low specific surface region, and (iv) the expense of reagents utilization. To improve the economy of the process, it is likewise needed to expand the catalyst’s effectiveness. Consequently, there is an extraordinary requirement for the improvement of elite catalysts. This mini-review survey addresses the basics and uses of photocatalytic materials on metal tungstate-based nanocomposites. The mini-review shows how metal tungstate-based nanocom-posites can help take care of ecological issues. This mini-review also expected survey gives outlines, synthesis, characterizations, and exploration discoveries in the field of metal tungstate-based nanocomposites for photocatalytic applications in the future examination.

Forced Displacement and Globalization in Latin America

Forced displacement in Latin America has dramatically increased in the twenty-first century. The vast majority of forced displacements in 2016 took place in high-risk zones characterized by low institutional reaction capacity, high levels of economic vulnerability, and high exposure to man-made and natural dangers. The new complexities of this old regional phenomenon demand that we revise our understanding of forced displacement and asylum seeking, as both are no longer exclusively caused by internal armed conflicts. Recent cases in countries such as Colombia, Venezuela, Mexico, Guatemala, El Salvador, and Honduras allow us to discern myriad factors driving forced displacements and diverse mobilities in the region, which could in turn bring another, deeper humanitarian crisis in Latin America. This contribution addresses these topics vis-à-vis the new forms of violence and displacement in the region.

The grounds for the modification of membranes with the help of quantum mechanical calculation method

In the process of water purification to increase the reflective capacity of ultrafiltration membranes, their surface modification is applied with aluminium oxychloride and polyhexamethylene guanidine hydrochloride are used. This enables to extract organic contaminations at 90% level, not less their salt balance. To estimate the reaction capacity, the method of calculation of energetic parameters and structural characteristics with the help of chemical analysis quanta is applied. For the analysis, the semiempirical method of modified neglect of diatomic overlapping is used. The prospective estimation of gel layer formation on the membrane surface is made. The method of molecular mechanics is applied in quantumchemical calculations for each substance and the material of the membrane. While analyzing the interaction between the material of the membrane and membrane-forming supplement, the charges on molecules` atoms, the determination of energetic levels of the lower vacant and upper filled molecular orbitals and energetic gap are estimated. It was proved that aluminium oxychloride precipitates on the membrane surface due to Van der Waltz forces, and the inoculation of polyhexamethylene guanidine occurs at fiber functionalization through the formation of hydrogen type of bond between the groups С≡N polymer and =N-H group. Scientific substantiation of membrane modification was obtained.

Preparation of Electrospun Active Molecular Membrane and Atmospheric Free Radicals Capture

We load the natural active molecules onto the spin film in an array using electrospinning techniques. The electrospun active molecular membranes we obtain in optimal parameters exhibit excellent capacity for scavenging radical. The reaction capacity of three different membranes for free radicals are shown as follow, glycyrrhizin acid membrane > quercetin membrane > α-mangostin membrane. The prepared active molecular electrospun membranes with a large specific surface area and high porosity could increase the interaction area between active molecules and free radicals. Additionally, it also has improved anti-airflow impact strength, anti-contaminant air molecular interference ability, and the ability to capture free radicals.