UHMWPE/SBA-15 nanocomposites synthesized by in situ polymerization

Different nanocomposites have been attained by in situ polymerization based on ultra-high molecular weight polyethylene (UHMWPE) and mesoporous SBA-15, this silica being used for immobilization of the FI catalyst bis [N-(3-tert-butylsalicylidene)-2,3,4,5,6-pentafluoroanilinato] titanium (IV) dichloride and as filler as well. Two distinct approaches have been selected for supporting the FI catalyst on the SBA-15 prior polymerization. A study on polymerization activity of this catalyst has been performed under homogenous conditions and upon heterogenization. A study of the effect of presence of mesoporous particles and of the immobilization method is also carried out. Moreover, the thermal characterization, phase transitions and mechanical response of some pristine UHMWPEs and UHMWPE/SBA-15 materials have been carried out. Relationships with variations on molar mass, impregnation method of catalyst and final SBA-15 content have been established

Petroagression deconstructed: variational propositions

It is widely believed that “petrostates,” or countries whose economies rely heavily on oil exports, are at greater risk from external aggression. This popular view has made frequent recourse to the neo-Malthusian intuition that, in a world of material scarcity, resource predation will be rampant. Recent empirical research, however, has shown that petrostates are neither more common targets of military attack nor particularly peaceful members of the international community. In fact, available statistical analyses overwhelmingly suggest that, in terms of conflict initiation, these states are mostly on the offensive in world politics—a phenomenon often referred to as “petroagression.” Despite this finding, little is known about what accounts for variation in petrostate belligerence. Not all petrostates are international troublemakers, and their propensity to threaten or use military force has varied both across geography and over time. This dissertation attempts to explain this within-group variation, using two conceptual experiments. The first heeds to the internal organization of petrostates, examining how differences in their regime institutions could mediate (strengthen or weaken) the conflict-inducing effects of oil income. It is argued that, because of certain compositional and identity characteristics of their ruling coalitions, petrostates with personalist institutions would be more potent conflict initiators than comparable oil exporters of nonpersonalist institutional makeup. The second conceptual experiment abstracts from petrostates’ internal attributes, exploring potential sources of variation in their external environments. Adopting a system–subsystem perspective, this analysis proposes that, all else equal, exogenous structural variables—in particular, superpower penetration in regional subsystems containing petrostates—could account for differences (spatial and temporal) in those states’ conflict behavior. Although the dissertation’s main thrust is theoretical, empirical evidence providing preliminary support for these variational propositions is also offered

Analysis of surgical treatment of duodenal ulcers with multiple combined complications

The aim of the research. Analysis of results and development of surgical tactics for the treatment of DU with multiple combined complications. Materials and methods. The results of the analysis of surgical treatment of duodenal ulcers with multiple combined complications (3 and 4 combined complications) for 3 periods are presented: 1st (1983–1995) (group A) – 77 patients, 2nd (2000–2007) years (group B) – 30 patients and 3rd (2008–2020) (group C) – 46 patients. Results. 153 patients (100 %) underwent surgery for complicated duodenal ulcer (DU), of which 130 patients (84.9 %) had a combination of three complications and 23 (15.1 %) had four complications. Bleeding complications were noted in 139 of 153 patients, accounting for 90.8 %, and ulcer perforation in 69 patients, accounting for 45.1 % of all other complications. Based on the obtained data of the analysis, there is a steady tendency to increase the proportion of organ-preserving operations (OPO) by 1.5 times (from 50.7 % to 76.2 %), reducing the number of gastrectomy (GR) by 3 times (from 14.5 % to 4.8 %) and palliative operations (PAL) 3.3 times (from 15.8 % to 4.8 %) with a relatively stable number of performed organ-saving operations (OSO): in group A – 17 (24.6 %) interventions, in group B – 4 (21.1 %), group C – 6 (14.3 %). Conclusions. The use of modern measures of endoscopic hemostasis allowed to operate on patients in the delayed period, and their share from the second period to the third increased 2.8 times. The number of patients who underwent emergency surgery with perforation of the ulcer as one of the complications decreased in the third period compared to the second by 2.6 times, due to the widespread use of PPIs in the conservative treatment of DU. According to the results of the analysis it became known that the chosen active-individualized tactics and developed algorithms for choosing the type of surgery allowed to achieve a stable level of postoperative mortality at 8.3 %

One-step synthesis of 2,5-bis(chloromethyl)-1,4-dioxane from epichlorohydrin using ZIF-8, taking advantage of structural defects

We demonstrate herein the ZIF-8-only-mediated catalysis of the cyclodimerization of epichlorohydrin to 2,5-bis(chloromethyl)-1,4-dioxane in the absence of co-catalyst and solvent. The easy handling and economic aspects of ZIF-8, in addition to the one-step reaction to produce the cyclodimer, make this catalyst attractive even for industry. It has been clearly illustrated that the nature of the method used to synthesize ZIF-8 affected the yields of the cyclodimers. Specifically, the method employed to produce ZIF-8 directly influences the amount of crystal structural defects, which in turn impacts their performance as catalysts. To emphasize the role of defects, other physical properties, such as surface area and particle size, were controlled during the synthesis of the ZIF-8 catalysts. Remarkably, the amount of structural defects was quantified by temperature program desorption analysis

Data on the largest specimens of Testudo graeca ibera Pallas, 1814 found in Bulgaria with five new records

Very large specimens of T. graeca ibera were found in Bulgaria, but mostly in the 20th century. Presently, such tortoises are almost absent in the country. Here we summarise data about the largest spur-thighed tortoises registered in Bulgaria and provide information about five new large-sized individuals. We also draw attention to the fact that large specimens can hardly be found in the country today and discuss some possible negative effects of the extinction of these specimens on the existing populations. The maximum straight carapace length of the largest T. graeca ibera ever found in Bulgaria was ≈ 389 mm, but the maximum straight carapace length of the newly measured tortoises was 298 mm. Considering the rarity of such tortoises in the country today, the genes that determine the potential to reach larger sizes may gradually disappear. Thus, the institutions responsible for the conservation of nature should pay attention to areas where the presence of large-sized individuals has been established. This might help preserve the natural genome of T. graeca ibera in the country and therefore the existence of large individuals

Do Electric Vehicles Mitigate Urban Heat? The Case of a Tropical City

On top of their well known positive impact on air quality and CO2 emissions, electric vehicles generate less exhaust heat compared to traditional vehicles thanks to their high engine efficiency. As such, electric vehicles have the potential to mitigate the excessive heat in urban areas—a problem which has been exacerbated due to urbanisation and climate change. Still, the heat mitigation potential of electric vehicles has not been fully understood. Here, we combine high-resolution traffic heat emission inventories with an urban climate model to simulate the impact of the fleet electrification to the near-surface air temperature in the tropical city of Singapore. We show that a full replacement of traditional internal combustion engine vehicles with electric vehicles reduces the near-surface air temperature by up to 0.6°C. The heat mitigation potential is highest during the morning traffic peak and over areas with the largest traffic density. Interestingly, the reduction in exhaust heat emissions due to the fleet electrification during the evening traffic peak hardly leads to a reduction of near-surface air-temperatures, which is attributed to the different atmospheric conditions during morning and evening. This study presents a new quantification of the city-wide impact of electric vehicles on the air temperature in a tropical urban area. The results may support policy-makers toward designing holistic solutions to address the challenge of climate change adaptation and mitigation in cities.Peer Reviewe

First survey on the invasive Pond slider (Trachemys scripta) in Bulgaria: historic development and current situation

Crvenouha kornjača (Trachemys scripta) postala je popularni ljubimac u Bugarskoj od 1990. Kroz godine sve veći broj jedinki zabilježen je i u divljini. Iako su negativni učinci na izvornim kornjače su opsežno studirao negdje drugdje, nema posebne studije (osim kratkih izvješća) obratili invaziju T. scripta u Bugarskoj. Ova studija se temelji na više od 25 godina praćenja na terenu i predstavlja prvi izvor detaljne informacije o raspodjeli Pond klizača u Bugarskoj. Ukupno 293 UTM (10 × 10 km) kvadrata sa staništa pogodna za slatkovodne kornjače ispitano. Prikupili smo 64 zapisa za 173 osoba, od 19 UTM kvadrata. Od svih promatranih osoba, samo dvije su od nominirati podvrste - ostatak pripada T. Š. elegans. U našem istraživanju je uočeno samo jednoga djeteta. Do danas nije uspješno leženja zabilježena, iako su registrirani uspješni overwinterings. Mi smo razgovarali o raznim mjere ublažavanja koje se moraju brzo pokrenut ograničiti buduće izdanje Ribnjak klizača i za uklanjanje ne-izvornih uzoraka s bugarskim ekosustava. Akcije su zahtijevali posebno da se izbjegne potencijalne epidemiološko događaja uzrokovanih parazitima s vrlo smrtonosnim učinkom na autohtonim vrstama. Takve pojave potencijalno mogu imati veći utjecaj na autohtone vrste kornjača jezerce od raznih oblika natjecanja s T. scripta.Pond sliders (Trachemys scripta) have become a popular pet in Bulgaria since 1990. Through the years a number of released specimens were observed in the wild. Although the negative effects on native turtles have been studied extensively elsewhere, no specific studies (besides brief reports) have addressed the invasion of T. scripta in Bulgaria. The present study is based on over 25 years of field monitoring and represents the first source of detailed information on the distribution of the Pond slider in Bulgaria. A total of 293 UTM (10×10 km) squares with habitats suitable for freshwater turtles were surveyed. We collected 64 records for 173 individuals, from 19 UTM squares. From all observed individuals, only two were from the nominate subspecies – the rest belong to T. s. elegans. In our study only one subadult was observed. To date no successful hatching has been recorded, although successful overwinterings have been registered. We discuss various mitigation measures that must be rapidly initiated to limit future release of Pond sliders and to remove the non-native specimens from the Bulgarian ecosystems. Actions are demanded especially to avoid the potential epizootic events caused by parasites with highly lethal effect on native species. Such outbreaks might potentially have greater impact on the native pond turtle species than various forms of competition with T. scripta

Промислові та непромислові види риб річок Липецької області

The list and fish assemblage species structure of 13 rivers of the Lipetsk region were analyzed. Classi-fication of the fish fauna from the viewpoint of fishery and nature protection was made for the working out of the concept of rational nature management. Important protected and threatened species was found in the Lipetsk area. It is established that not all species included in the regional Red Data Book correspond to their real nature protection status.Проанализированы состав и таксономическая структура ихтиофауны рек Липецкой области. Проведена рыбохозяйственная и природоохранная классификация ихтиофауны, необходимая для разработки концепции рационального природопользования. На территории области выделены особо охраняемые виды и находящиеся под угрозой исчезновения. Установлено, что не все виды, занесенные в Красную книгу области, соответствуют их истинному природоохранному статусу.Проаналізовано склад і таксономічну структуру іхтіофауни річок Липецької області. Проведено рибогосподарську та природоохоронну класифікацію іхтіофауни, необхідну для розробки концепції раціонального природокористування. На території області виділено особливо охоронювані види та види, які перебувають під загрозою зникнення. Встановлено, що не всі види, занесені до Червоної книги області, відповідають їх справжньому природоохоронному статусу