Influence of waxes remelting used in investment casting on their thermal properties and linear shrinkage

This paper presents the results of thermal properties and linear shrinkage of jewelry waxes utilized in investment casting. Three types of jewelry waxes were cyclically processed (by heating, holding in a molten state and cooling)in the temperature range between 25 and 90 °C for about 7 hours. The samples were tested after 5th, 10th and 15thcycle. The remelting was designed to simulate the process of waxes reusability for production of patterns. Changes in thermal properties of waxes were determined using differential scanning calorimetry (DSC) and linear shrinkage values were specified. The conducted examinations allowed to establish the way of multiple utilization of waxes in producing precise models

Plasmodium-Induced Inflammation by Uric Acid

Infection of erythrocytes with the Plasmodium parasite causes the pathologies associated with malaria, which result in at least one million deaths annually. The rupture of infected erythrocytes triggers an inflammatory response, which is induced by parasite-derived factors that still are not fully characterized. Induced secretion of inflammatory cytokines by these factors is considered a major cause of malaria pathogenesis. In particular, the inflammatory cytokine tumor necrosis factor (TNF) is thought to mediate most of the life-threatening pathologies of the disease. Here we describe the molecular characterization of a novel pathway that results in the secretion of TNF by host cells. We found that erythrocytes infected by Plasmodium accumulate high concentrations of hypoxanthine and xanthine. Degradation of Plasmodium-derived hypoxanthine/xanthine results in the formation of uric acid, which triggers the secretion of TNF. Since uric acid is considered a “danger signal” released by dying cells to alert the immune system, Plasmodium appears to have co-evolved to exploit this warning system. Identifying the mechanisms used by the parasite to induce the host inflammatory response is essential to develop urgently needed therapies against this disease

Correction: Population Genomics of the Immune Evasion (var) Genes of Plasmodium falciparum

Var genes encode the major surface antigen (PfEMP1) of the blood stages of the human malaria parasite Plasmodium falciparum. Differential expression of up to 60 diverse var genes in each parasite genome underlies immune evasion. We compared the diversity of the DBLalpha domain of var genes sampled from 30 parasite isolates from a malaria endemic area of Papua New Guinea (PNG) and 59 from widespread geographic origins (global). Overall, we obtained over 8,000 quality-controlled DBLalpha sequences. Within our sampling frame, the global population had a total of 895 distinct DBLalpha "types" and negligible overlap among repertoires. This indicated that var gene diversity on a global scale is so immense that many genomes would need to be sequenced to capture its true extent. In contrast, we found a much lower diversity in PNG of 185 DBLalpha types, with an average of approximately 7% overlap among repertoires. While we identify marked geographic structuring, nearly 40% of types identified in PNG were also found in samples from different countries showing a cosmopolitan distribution for much of the diversity. We also present evidence to suggest that recombination plays a key role in maintaining the unprecedented levels of polymorphism found in these immune evasion genes. This population genomic framework provides a cost effective molecular epidemiological tool to rapidly explore the geographic diversity of var genes

Population Genomics of the Immune Evasion (var) Genes of Plasmodium falciparum

Var genes encode the major surface antigen (PfEMP1) of the blood stages of the human malaria parasite Plasmodium falciparum. Differential expression of up to 60 diverse var genes in each parasite genome underlies immune evasion. We compared the diversity of the DBLα domain of var genes sampled from 30 parasite isolates from a malaria endemic area of Papua New Guinea (PNG) and 59 from widespread geographic origins (global). Overall, we obtained over 8,000 quality-controlled DBLα sequences. Within our sampling frame, the global population had a total of 895 distinct DBLα “types” and negligible overlap among repertoires. This indicated that var gene diversity on a global scale is so immense that many genomes would need to be sequenced to capture its true extent. In contrast, we found a much lower diversity in PNG of 185 DBLα types, with an average of approximately 7% overlap among repertoires. While we identify marked geographic structuring, nearly 40% of types identified in PNG were also found in samples from different countries showing a cosmopolitan distribution for much of the diversity. We also present evidence to suggest that recombination plays a key role in maintaining the unprecedented levels of polymorphism found in these immune evasion genes. This population genomic framework provides a cost effective molecular epidemiological tool to rapidly explore the geographic diversity of var genes

Psychological distress among healthcare students in Poland from COVID-19 to war on Ukraine: a cross-sectional exploratory study

ObjectivesHealthcare students went through a rough time in March 2022 due to extreme changes in the educational system (moving from online to stationary learning) and Ukrainian-Russian war circumstances. Our study aims to update knowledge about psychological distress and its impact on healthcare students in Poland after two years of the COVID-19 pandemic, followed by intense and political instability in Europe.MethodsWe conducted a cross-sectional study on healthcare students from Poznan University of Medical Sciences, Poland, from March to April 2022. The questionnaire included subjective retrospective 5-point Likert-scales ratings of anxiety, stress, and depression and self-reported information on various psychological distress predictors.ResultsThe anxiety levels at the beginning of the COVID-19 pandemic were higher than in April 2022. There was no significant reduction in stress and depression. Females had higher initial anxiety levels than post-pandemic levels. Higher reported levels of anxiety, stress, and depression were significantly correlated with political instability in Eastern Europe (Spearman ranxiety = 0.178, rstress = 0.169, rdepression = 0.154, p ≤ 0.001, respectively). The concern about moving towards online education showed a significant association only with stress level (rstress = 0.099, p = 0.034). We also observed a positive correlation between anxiety, stress, and depression and deteriorating sleep quality (Spearman ranxiety,=0.325, rstress = 0.410, rdepression = 0.440, p < 0.001), the feeling of worsening relationships with family and peers (ranxiety = 0.325, rstress = 0.343, rdepression = 0.379, p < 0.001), and the sense of loss of efficient time management (ranxiety = 0.321, rstress = 0.345, rdepression = 0.410, p < 0.001).ConclusionThroughout the progression of the Ukrainian war and the COVID-19 pandemic, females reported improved (lower levels) levels of anxiety. Nevertheless, the current levels of self-reported anxiety post-pandemic remain alarming, while stress and depression levels remained unchanged. Mental, psychological, and social support activities are required for healthcare students, especially those away from their families. Time management, academic performance, and coping skills in relation to the additional stressors of war and the global pandemic require further research in this group of students

Uric Acid Is a Mediator of the Plasmodium falciparum-Induced Inflammatory Response

Malaria triggers a high inflammatory response in the host that mediates most of the associated pathologies and contributes to death. The identification of pro-inflammatory molecules derived from Plasmodium is essential to understand the mechanisms of pathogenesis and to develop targeted interventions. Uric acid derived from hypoxanthine accumulated in infected erythrocytes has been recently proposed as a mediator of inflammation in rodent malaria.We found that human erythrocytes infected with Plasmodium falciparum gradually accumulate hypoxanthine in their late stages of development. To analyze the role of hypoxanthine-derived uric acid induced by P. falciparum on the inflammatory cytokine response from human blood mononuclear cells, cultures were treated with allopurinol, to inhibit uric acid formation from hypoxanthine, or with uricase, to degrade uric acid. Both treatments significantly reduce the secretion of TNF, IL-6, IL-1beta and IL-10 from human cells.Uric acid is a major contributor of the inflammatory response triggered by P. falciparum in human peripheral blood mononuclear cells. Since the inflammatory reaction induced by P. falciparum is considered a major cause of malaria pathogenesis, identifying the mechanisms used by the parasite to induce the host inflammatory response is essential to develop urgently needed therapies against this disease

A Molecular Epidemiological Study of var Gene Diversity to Characterize the Reservoir of Plasmodium falciparum in Humans in Africa

BACKGROUND: The reservoir of Plasmodium infection in humans has traditionally been defined by blood slide positivity. This study was designed to characterize the local reservoir of infection in relation to the diverse var genes that encode the major surface antigen of Plasmodium falciparum blood stages and underlie the parasite's ability to establish chronic infection and transmit from human to mosquito. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the molecular epidemiology of the var multigene family at local sites in Gabon, Senegal and Kenya which differ in parasite prevalence and transmission intensity. 1839 distinct var gene types were defined by sequencing DBLα domains in the three sites. Only 76 (4.1%) var types were found in more than one population indicating spatial heterogeneity in var types across the African continent. The majority of var types appeared only once in the population sample. Non-parametric statistical estimators predict in each population at minimum five to seven thousand distinct var types. Similar diversity of var types was seen in sites with different parasite prevalences. CONCLUSIONS/SIGNIFICANCE: Var population genomics provides new insights into the epidemiology of P. falciparum in Africa where malaria has never been conquered. In particular, we have described the extensive reservoir of infection in local African sites and discovered a unique var population structure that can facilitate superinfection through minimal overlap in var repertoires among parasite genomes. Our findings show that var typing as a molecular surveillance system defines the extent of genetic complexity in the reservoir of infection to complement measures of malaria prevalence. The observed small scale spatial diversity of var genes suggests that var genetics could greatly inform current malaria mapping approaches and predict complex malaria population dynamics due to the import of var types to areas where no widespread pre-existing immunity in the population exists

Sustainable development and production processes for the construction of antropogenic objects

Zrównoważony rozwój jest koniecznością wobec bardzo szybkiego tempa przyrostu ludności świata, rosnącego zapotrzebowania na surowce oraz energię, zwiększanie poziomu aspiracji społeczeństw. W artykule omówiono tematykę zrównoważonego rozwoju (ZR) w odniesieniu do budownictwa gdzie realizacja założeń ZR ma strategiczne znaczenie dla ochrony środowiska naturalnego. Podkreślono zasadność rozwijania technologii wytwarzania materiałów i wyrobów budowlanych, których wytwarzanie i stosowanie wpisują się w uwarunkowania zrównoważonego rozwoju (np. autoklawizowany beton komórkowy). Zwrócono uwagę na potrzebę zrozumienia, że na technologię wytwarzania nie można patrzeć tylko od strony rozwiązania technicznego, możliwości sprzedaży produktu ale również należy je bezwzględnie odnosić do zagadnień ekologicznych, ekonomicznych i społecznych. Podkreślono zasadność projektowania zintegrowanego szczególnie w fazie projektowania inwestycji co pozwala na osiągnięcie wspólnego celu jakim jest zaplanowane wybudowanie i użytkowanie budynku antropogenicznego zoptymalizowanego pod względem zużycia energii pierwotnej, obciążenia środowiska naturalnego i kosztów określonych w cyklu życia budynku przy zapewnieniu realizacji zadanej funkcji użytkowej. Wskazano na zasadność podejmowania wspólnych inicjatyw organizacji o zasięgu światowym, ponad rządowych, międzynarodowych, stowarzyszeń międzynarodowych i organizacji normalizacyjnych (CEN, ISO) dla realizacji zrównoważonego rozwoju w skali świata.Sustainable development is a necessity in view of the very rapid growth of the world population, the increasing demand for raw materials and energy, the increasing aspirations of the population. The article discusses the topic of sustainable development (ZR) in construction, where the implementation of the ZR is of strategic importance for the protection of the environment. The importance of developing technologies for the manufacture of building materials and products, the production and use of which are in line with sustainable development (eg autoclaved aerated concrete) have been emphasized. Attention was drawn to the need to understand that the technology of production can not be seen only from the technical side of the product, but also on the ecological, economic and social aspects of the product. It emphasized the importance of integrated design especially in the investment design stage, which allows to achieve the common goal of the planned construction and use of the anthropogenic building optimized for primary energy consumption, environmental load and life cycle costs, while ensuring the required function. It has been suggested that international organizations, worldwide, international associations and standardization organizations (CEN, ISO) should work together to achieve sustainable development on a global scale

Exploitation cements CEM II and CEM V in producing autoclaved aerated concrete (AAC)

Przedstawiono możliwości stosowania cementów wieloskładnikowych do produkcji autoklawizowanego betonu komórkowego (ABK). W zakresie technologii ABK praca ma charakter nowatorski. Obok rozwiązań praktyczno-technologicznych przedstawiono wyniki badań składu fazowego i mikrostruktury ABK, produkowanego przy stosowaniu różnych cementów wieloskładnikowych, zawierających duże ilości dodatków mineralnych. Wyniki pracy stanowią istotny wkład wiedzy w zakresie technologii ABK. Realizacja tematu stwarza przesłanki wdrożenia w technologii betonu komórkowego stosowania cementów wieloskładnikowych w miejsce obecnych rozwiązań z wykorzystaniem cementu portlandzkiego CEM I.In the article was presented a possibility of applying multicomponent cements for the production of autoclaved aerated concrete (AAC). In the AAC this work have innovative character. Besides solutions practical and technological in article we can find research of the phase composition and microstructures of AAC, produced at applying different multicomponent cements, containing lot of mineral supplements. Results of the work constitute the essential contribution of the knowledge in the ABK technology. Realization of this work is creating reasons to implementation use multicomponent cements in the AAC technology, in place present technical solution with using portland cement CEM I