Trends of the major porin gene (ompF) evolution

OmpF is one of the major general porins of Enterobacteriaceae that belongs to the first line of bacterial defense and interactions with the biotic as well as abiotic environments. Porins are surface exposed and their structures strongly reflect the history of multiple interactions with the environmental challenges. Unfortunately, little is known on diversity of porin genes of Enterobacteriaceae and the genus Yersinia especially. We analyzed the sequences of the ompF gene from 73 Yersinia strains covering 14 known species. The phylogenetic analysis placed most of the Yersinia strains in the same line assigned by 16S rDNA-gyrB tree. Very high congruence in the tree topologies was observed for Y. enterocolitica, Y. kristensenii, Y. ruckeri, indicating that intragenic recombination in these species had no effect on the ompF gene. A significant level of intra- and interspecies recombination was found for Y. aleksiciae, Y. intermedia and Y. mollaretii. Our analysis shows that the ompF gene of Yersinia has evolved with nonrandom mutational rate under purifying selection. However, several surface loops in the OmpF porin contain positively selected sites, which very likely reflect adaptive diversification Yersinia to their ecological niches. To our knowledge, this is a first investigation of diversity of the porin gene covering the whole genus of the family Enterobacteriaceae. This study demonstrates that recombination and positive selection both contribute to evolution of ompF, but the relative contribution of these evolutionary forces are different among Yersinia species

Different siderophores contribute to the high-pathogenicity phenotype in Yersinia

capture and transport in bacteria. At least one endogenous siderophore system, yersiniabactin, is known to be involved in iron acquisition in highly virulent Yersiniae . Its inactivation in Y. pestis and Y. enterocolitica subsp. enterocolitica results in significant attenuation of virulence. However, the yersiniabactin is not present in all highly virulent Yersiniae. Indeed, the large group of Y. pseudotuberculosis serotypes O2, O3, O4, O5 as well as serotype O1 Far East Scarlet like fever (FESLF) strains carry an alternative, iron acquisition system, pseudochelin, encoded by the Yersinia non-ribosomal peptide ynp locus. Thus, the yersiniabactin activity is not the only one associated with the high-pathogenicity phenotype of the human pathogenic Yersiniae

Influence of friction stir welding parameters on properties of 2024 t3 aluminium alloy joints

The aim of this work is to analyse the process of friction stir welding (FSW) of 3 mm thick aluminium plates made of high strength aluminium alloy - 2024 T3, as well as to assess the mechanical properties of the produced joints. Friction Stir Welding is a modern procedure which enables joining of similar and dissimilar materials in the solid state, by the combined action of heat and mechanical work. This paper presents an analysis of the experimental results obtained by testing the butt welded joints. Tensile strength of the produced joints is assessed, as well as the distribution of hardness, micro-and macrostructure through the joints (in the base material, nugget, heat affected zone and thermo-mechanically affected zone). Different combinations of the tool rotation speed and the welding speed are used, and the dependence of the properties of the joints on these parameters of welding technology is determined

Numerical analysis of thermal stresses in welded joint made of steels x20 and x22

Stress calculation of steam pipeline is presented, focused on the welded joint. Numerical calculation was peiformed using the finite element method to obtain stress distribution in the welded joint made while replacing the valve chamber. Dissimilar materials were used, namely steel 10CrMoV9-10 according to EN 10216-2 for the valve chamber, the rest of steam pipeline was steel X20, whereas the transition piece material was steel X22. Residual stresses were calculated, in addition to design stresses, indicating critical regions and necessity for post-weld heat treatment

Radiotherapy-Induced Cherenkov Luminescence Imaging in a Human Body Phantom

Radiation therapy produces Cherenkov optical emission in tissue, and this light can be utilized to activate molecular probes. The feasibility of sensing luminescence from a tissue molecular oxygen sensor from within a human body phantom was examined using the geometry of the axillary lymph node region. Detection of regions down to 30-mm deep was feasible with submillimeter spatial resolution with the total quantity of the phosphorescent sensor PtG4 near 1 nanomole. Radiation sheet scanning in an epi-illumination geometry provided optimal coverage, and maximum intensity projection images provided illustration of the concept. This work provides the preliminary information needed to attempt this type of imaging in vivo

Patient-specific, mechanistic models of tumor growth incorporating artificial intelligence and big data

Despite the remarkable advances in cancer diagnosis, treatment, and management that have occurred over the past decade, malignant tumors remain a major public health problem. Further progress in combating cancer may be enabled by personalizing the delivery of therapies according to the predicted response for each individual patient. The design of personalized therapies requires patient-specific information integrated into an appropriate mathematical model of tumor response. A fundamental barrier to realizing this paradigm is the current lack of a rigorous, yet practical, mathematical theory of tumor initiation, development, invasion, and response to therapy. In this review, we begin by providing an overview of different approaches to modeling tumor growth and treatment, including mechanistic as well as data-driven models based on ``big data" and artificial intelligence. Next, we present illustrative examples of mathematical models manifesting their utility and discussing the limitations of stand-alone mechanistic and data-driven models. We further discuss the potential of mechanistic models for not only predicting, but also optimizing response to therapy on a patient-specific basis. We then discuss current efforts and future possibilities to integrate mechanistic and data-driven models. We conclude by proposing five fundamental challenges that must be addressed to fully realize personalized care for cancer patients driven by computational models

Micromechanical Coupled Study of Crack Growth Initiation Criterion in Pressure Vessel Steel

We present results of the combined design-theoretical investigation of the mechanism of crack growth at the onset of ductile fracture of NPP reactor pressure vessels. Micromechanical approach to the prediction of ductile fracture has been applied, according to which the volume fraction of voids in the deformed material is determined by finite-element method. On the basis of CT-specimen tests and known damage parameters, obtained on smooth spherical specimens, we obtained micromechanical criterion of crack growth initiation for ductile fracture.Представлены результаты комплексного расчетно-экспериментального исследования механизма распространения трещины на начальном этапе вязкого разрушения корпусных сталей АЭС. Использован микромеханический подход к прогнозированию вязкого разрушения, согласно которому объемное содержание пор деформируемого материала определяется методом конечных элементов. На основании проведенных испытаний образцов СТ с трещиной и имеющихся данных о параметрах разрушения гладких сферических образцов установлен микромеханический критерий начала развития трещины в условиях вязкого разрушения материала.Представлено результати комплексного розрахунково-експериментального дослідження механізму розповсюдження тріщини на початковому етапі в’язкого руйнування корпусних сталей АЕС. Використовується мікромеха- нічний підхід до прогнозування в ’язкого руйнування, згідно з яким об’ємний вміст пор деформівного матеріалу визначається методом скінченних елементів. На основі проведених випробувань зразків СТ із тріщиною та відомих даних про параметри руйнування гладких сферичних зразків установлено мікромеханічний критерій початку розвитку тріщини в умовах в ’язкого руйнування

Change of temperature and vertical force during friction stir welding

Cilj rada je analiza promene vertikalne sile i temperature tokom procesa zavarivanja trenjem mešanjem (FSW) legura aluminijuma visoke čvrstoće (2024 T3). FSW postupak je složen nelinearan proces praćen velikim plastičnim deformacijama, visokim temperaturama i plastičnim tečenjem materijala u zoni zavarivanja. To je postupak spajanja materijala u tzv. čvrstoj fazi, kombinovanim delovanjem toplote i mehaničkog rada. Analiza promene sile i temperature tokom procesa zavarivanja omogućava bolje razumevanje i kontrolu samog procesa. U radu je analizirana i praćena promena sile u vertikalnom pravcu pomoću dinamometra i promena temperature na gornjoj površini radne ploče u blizini čela valjka alata pomoću termovizijske kamere.The aim of this paper is to analyze changes of vertical force and temperature during friction stir welding process of high strength aluminum alloys (2024 T3). FSW process is a complex nonlinear process accompanied by large plastic deformation, high temperatures and plastic material flow in the welding zone. It is the procedure of material connecting in the so-called solid phase, through the combined action of heat and mechanical work. Analysis of force and temperature changes during the process of welding allows better understanding and control of the process. This paper analyzes the change of force in the vertical direction using a dynamometer and temperature changes on the upper surface of the working panel near the tops of the roller tool using thermal imaging cameras

Advantages of friction stir welding over arc welding with respect to health and environmental protection and work safety [Prednosti zavarivanja trenjem sa mešanjem u odnosu na elektrolučno zavarivanje - Zaštita zdravlja i životne sredine i bezbednost na r

In modern industrial production, every manufacturing and assembly process should be assessed with respect to its influence on the environment. For a company that invests in a new process, a careful analysis of HSE problems (Health, Safety and Environment) is very important. Friction stir welding (FSW) process offers numerous advantages regarding health protection, environmental effects and work safety in comparison with other welding procedures, such as arc welding. Arc welding produces a broad spec-trum of UV radiation, harmful for human health (skin, eyes). Exposure to this radiation without an adequate protection can lead to severe injuries. If appropriate protective measures are undertaken, the welder can easily be exposed to heat injuries. This is especially pronounced for arc welding of aluminium alloys, because high material conductivity of Al requires a high-energy arc, and also because its surface has more pronounced reflection than steel. This work deals with the FSW welding process and its advantages in comparison with arc welding processes with respect to health protection, environmental problems and work safety

Advantages of friction stir welding over arc welding with respect to health and environmental protection and work safety [Prednosti zavarivanja trenjem sa mešanjem u odnosu na elektrolučno zavarivanje - Zaštita zdravlja i životne sredine i bezbednost na r

In modern industrial production, every manufacturing and assembly process should be assessed with respect to its influence on the environment. For a company that invests in a new process, a careful analysis of HSE problems (Health, Safety and Environment) is very important. Friction stir welding (FSW) process offers numerous advantages regarding health protection, environmental effects and work safety in comparison with other welding procedures, such as arc welding. Arc welding produces a broad spec-trum of UV radiation, harmful for human health (skin, eyes). Exposure to this radiation without an adequate protection can lead to severe injuries. If appropriate protective measures are undertaken, the welder can easily be exposed to heat injuries. This is especially pronounced for arc welding of aluminium alloys, because high material conductivity of Al requires a high-energy arc, and also because its surface has more pronounced reflection than steel. This work deals with the FSW welding process and its advantages in comparison with arc welding processes with respect to health protection, environmental problems and work safety