Structural, chemical and deformation changes in friction welded joint of dissimilar steels

Fundamental principles of friction welding of dissimilar steels (high speed and tempering steel) from the aspect of metallurgical and chemical processes occurring in the joint zone are presented in this paper. Considering that phenomena accompanying the friction welding are interdependent, it was necessary to experimentally determine the process variable parameters, to establish the optimal welding regime. The experiments were set and realized so that all the variables were analyzed as a function of the friction time. The metallographic investigations included analysis of the joint zone microstructure through structural phases and hardness changes, due to influence of the heat treatment - annealing. The experimental work included analysis of the geometry changes, the joint zone structure and the basic mechanical characteristics of the joint realized by the friction welding

Community-hygiene problems of public surfaces and environmental protection measures at the territory of the Belgrade settlement

Предмет истраживања докторске дисертације је геопросторни аспект комуналне хигијене и проблеми који постоје у заштити и унапређењу квалитета животне средине на јавним површинама у градском насељу Београд. Коришћена методологија може бити примењена и за друга градска насеља у Републици Србији. Осим сагледавања институционалног оквира (хијерархијски нивои власти у држави, органи Градске управе Града Београда, надлежне институције, предузећа и др.), дат је преглед надлежности јединице локалне самоуправе и законски и стратешки оквир управљања животном средином и комуналном хигијеном, као и природно-географске и социоекономске карактеристике градског насеља Београд. Анализирани су квалитет медијума животне средине (вода, ваздух, земљиште, итд.) и фактори који утичу на њихов квалитет, као и пројекти и активности који ће у наредном периоду унапредити комунално-хигијенске услове у појединим деловима града. Појединачно су анализирани комунално-хигијенски проблеми на јавним површинама и наведене су препоруке за њихово ублажавање или потпуно уклањање, док су кроз посебна поглавља анализирани комунално- хигијенски проблеми градског зеленила и управљања отпадом. Предлог интегралног модела управљања комуналном хигијеном на територији градског насеља Београд који је дат у дисертацији, представља комплексан и интердисциплинаран приступ (мере, поступци и др.) решавању конкретних комунално-хигијенских проблема у систему заштитите животне средине, информационог система, политике, економије и техничко-технолошких решења.The research subject of the doctoral dissertation is the geospatial aspect of community hygiene and the problems that exist in protecting and improving the quality of the environment on public surfaces in the Belgrade settlement. The methodology used can also be applied to other urban settlements in the Republic of Serbia. In addition to the consideration of the institutional framework (hierarchical levels of the state government, the authorities of the City of Belgrade, competent institutions and enterprises, etc.), an overview of the local self-government competencies, legal and strategic framework for the environmental management and community hygiene is given, as well as the natural-geographic and socio-economic characteristics of the Belgrade settlement. The quality of the environmental media (water, air, soil, etc.) is analyzed along with the analyzed factors affecting their quality, as well as projects and activities that will improve the community-hygiene conditions in some parts of the city in the following period. The community-hygiene problems were analyzed separately. Recommendations for their mitigation or complete removal were given. On the other hand, the community-hygiene problems of urban greenery and waste management were analyzed through the special chapters. The proposal for the integral model of the community-hygiene management at the territory of Belgrade settlement given in the dissertation, represents complex and interdisciplinary approach (measures, procedures, etc.) for solving concrete community-hygiene problems in the environmental protection system, information system, politics, economy, and technical and technological solutions

Utilization of diffraction analysis in the study of martensitic weld deposits using tungsten carbide particles on S235JR+N steel

The durability of classic structural steels against various types of wear is generally low. Therefore, various types and combinations of resilient materials are constantly evolving, which are designed to reduce the cost of components replacement or repairs. This paper deals with the structures that are formed in a weld after addition of tungsten carbide particles to protect the surface of the components from wear. The resistance of the weld surface layer containing tungsten carbides is also evaluated in comparison with a layer without these particles

Two metallothionein gene family members in buckwheat: Expression analysis in flooding stress using Real Time RT-PCR technology

Metalotioneini (MT) pripadaju velikoj grupi proteina male molekulske težine bogatih cisteinom, izražene sposobnosti za vezivanje jona metala, uključenih u procese održavanja homeostaze metalnih jona i detoksifikacije od teških metala. U radu je analizirana struktura dva transkripta gena za MT tipa 3 poreklom iz semena heljde u razviću. Razlike su nađene pre svega u okviru 3’- UTR sekvenci. Nakon analiza sekvenci urađena je analiza ekspresije tokom hipoksije korišćenjem tehnologije Real Tme RT-PCR.Metallothioneins (MTs) are an extensive and diverse family of small cysteine-rich proteins with metal-binding ability that are involved in metal homeostasis and detoxification. Two cDNA clones of the MT3 type, differing in 3’ UTRs, were isolated from the developing buckwheat seed cDNA library. Following sequence analyses, expression profiles during flooding stress were monitored by Real Time RT PCR technology

Antioxidative enzymes in the response of buckwheat (Fagopyrum esculentum Moench) to complete submergence

Oxidative stress and antioxidative defense system activity were studied in buckwheat leaves after complete submergence and re-aeration. The levels of H2O2 and lipid peroxidation were found to be significantly higher in stressed than in untreated buckwheat leaves. Enzymes catalyzing the degradation of H2O2 and peroxides were shown to participate actively, whereas superoxide dismutase did not take part in the buckwheat leaf response to flooding stress. The most prominent increase in antioxidative enzyme activities was noticed upon return to air, when the strongest oxidative stress occurred and the need for antioxidative defense was the greatest

Transient expression in tobacco Bright Yellow 2 cells and pollen grains: A fast, efficient and reliable system for functional promoter analysis of plant genes

Ekspresija gena je regulisana posredstvom promotora-DNK sekvenci uzvodno od kodirajućeg regiona. Promotori svojom sekvencom određuju mesta vezivanja transkripcionih faktora, regulatora i RNK polimeraze. Strukturna i funkcionalna analiza promotora neophodna je za razumevanje mehanizama genske ekspresije. Cilj ovog rada je razvijanje brzog, efikasnog i pouzdanog sistema za testiranje bazalne promotorske aktivnosti kao i otkrivanje sekvenci polen-specifičnih elemenata promotora. U ovom radu je testirana funkcionalnost promotora za metalotionein heljde, posredstvom histohemijskog GUS-eseja u dva tranzijentna sistema za ekspresiju: BY2 ćelijama i polenovim zrnima. U oba sistema je uočena izražena aktivnost ispitivanog promotora.Gene expression is mediated by DNA sequences directly upstream from the coding sequences, recruited transcription factors and RNA polymerase in a spatially-defined manner. Understanding promoter strength and regulation would enhance our understanding of gene expression. The goal of this study was to develop a fast, efficient and reliable method for testing basal promoter activity and identifying core sequences within its pollen specific elements. In this paper we examined the functionality of buckwheat metallothionein promoter by a histochemical GUS assay in two transient expression systems: BY2 cells and pollen grains. Strong promoter activity was observed in both systems

Experimental determination of continuous cooling transformation diagram for high strength steel X155CrMoV12

The article is a result of investigations which deals with the phase transformations of tool steel X155CrMoV12. The experimental data obtained was used to evaluate the resulting Continuous Cooling Transform (CCT) diagram, which consists of seven dilation curves. All experimental samples from dilatometric analyzes were then subjected to microstructural analyzes and hardness measurements to characterize the microstructure and hardness for each heat treatment mode tested. Atomic Force Microscopy (AFM) microscopy was also used to study the carbides present in steels and their size and shape for all selected cooling modes

Dilatometric analysis of cooling curves for high strength steel X155CrMoV12

The article deals with phase transformations and austenitizing behavior of the X155CrMoV12 tool steel. Dilatation analyses of a series of samples were performed at various cooling rates, chosen in the range from 10 °C/s to 0,1°C/s. Acquired experimental data were used for evaluation of dilatometric curves in order to map the temperature ranges of phase transformations of the austenite to pearlite, bainite or martensite. All experimental samples from dilatometric analyses were then subjected to microstructural analyses and hardness measurements to characterize the microstructure and hardness for each tested heat treatment regime

Subacute thyroiditis following COVID-19 vaccination: Case presentation

Background:Subacute thyroiditis (SAT) is an organ-specific disease that various drugs, including COVID-19vaccines, can trigger. COVID-19 infection has been associated with thyroid gland damage and disease SARS-CoV-2direct action, euthyroid sick syndrome, and immune-mediated mechanisms are all potential mechanisms of thyroiddamage. It denotes thyroid gland inflammation, most commonly of viral origin, and belongs to the transitory, self-limiting thyroid gland diseases group, causing complications in approximately 15% of patients in the formof permanent hypothyroidism. Some authors say SAT is the most common thyroid disease associated withCOVID-19.Purpose:The occurrence of SAT many weeks after administering the second COVID-19 vaccine is rare and has limiteddocumentation in academic literature. This study aims to present the occurrence of SAT after administering the COVID-19vaccine. We present the case of a 37-year-old man who developed SAT 23 days after receiving the second dose of PfizerBioNTech’s COVID-19 mRNA vaccine.Research design and study sample:Due to neck pain and an elevated body temperature (up to 38.2°C), a 37-year-old male subject presented for examination 23 days after receiving the second Pfizer BioNTech mRNA vaccineagainst SARS-CoV-2 viral infection. The patient deniedever having an autoimmune disease or any other disease.Painful neck palpation and afirm, slightly enlarged thyroid gland with no surrounding lymphadenopathy wereidentified during the exam. The heart rate was 104 beatsper minute. All of the remaining physicalfindings werenormal.Data collection and/or Analysis:Data collected during the disease are integral to the medical record.Results:Hematology and biochemistry analyses at the initial and follow-up visits revealed minor leukocytosis, normocyticanaemia, and thrombocytosis, followed by a mild increase in lactate dehydrogenase and decreased iron levels. The patient’sthyroid function and morphology had recovered entirely from post-vaccine SAT.Conclusions: Results from this study emphasise the need for healthcare professionals to promptly report any case of SATrelated to COVID-19 vaccination. Further investigation is warranted to understand the immunopathogenesis of COVID-19-associated thyroiditis and the impact of COVID-19 immunization on this condition

Management of Non-Classic Congenital Adrenal Hyperplasia in Pregnant Woman - Non-Referral Center Experience- Case Report

Congenital adrenal hyperplasia (CAH) is a rare autosomal recessive disorder with mutations in genes involved in cortisol and aldosterone production. Based on overall 21-OHase activity, CAH is divided into classic (C-CAH) and non-classic (NC-CAH). Females who suffered from NC-CAH have had increased infertility rates and higher miscarriage susceptibility. The treatment of CAH in pregnancy is still debatable. We present 22-years-old pregnant female (seventh week of gestation), who is currently under dexamethasone (DEX) since almost seven years for NC-CAH. At presentation, she is normotensive, non-obese, with no signs of hirsutism and Cushing syndrome. Seven days after the first visit, an endocrinologist makes informative talk with the patient and her mother about NC-CAH, pregnancy, and drugsassociated risks. Current Clinical Practice Guideline for CAH treatment suggests the use of protocols approved by Institutional Review Boards at Centers experienced in CAH treatment. In women with CAH who are planning a pregnancy, a close relationship between endocrinologist, reproductive gynaecologist and molecular biologist is of great interest. Prenatal management with DEX is advised in particular circumstances. In remaining, the switch from DEX to other glucocorticoids that do not penetrate placenta is advise