Influence of Windows Geometrical Parameters on Calculations of the Heat Conduction Coefficient

© 2017 The Authors. The relationship between the geometrical and thermodynamic variables of windows, of several types, sizes and materials, is presented in this paper. The heat conduction coefficients were calculated, for all the presented windows' types. Results that are presented provide for the possibility to select the optimal construction solution of the window, as well as for the material of the frame and type of the filling, with respect to the best heat conduction coefficient. That, in turn, ensures the optimal energy efficiency of the window structure

Investigation of possible causes for appearance of a crack in the welded joint of the ship winch frame

Ship winches are one of the most important parts of the ship equipment since they perform the most responsible tasks on various ships. In the majority of cases, the ship winches are welded structures. All the necessary calculations according to required standards, that have to be done prior to actual execution of the structure, should also include the verification by the finite elements method. For the high reliability requirements to be met, the welded joints integrity of all the parts must be examined before they are assembled into the winch. After all the tests are conducted and parts are assembled into the winch, the factory acceptance test (FAT) must be done. During those tests all the flaws, which can appear during manufacturing, must show. An appearance of a very unusual crack in the ship winch frame, which happened during the FAT, is described in this paper. The simulation by the finite elements method was performed to obtain the stresses at which the crack appeared. The possible causes for that crack appearance are considered. Some measures for reducing appearance of such cracks to a minimum are proposed, as well as certain directions for further research of this problem.

PDK1-SGK1 signaling sustains AKT-independent mTORC1 activation and confers resistance to PI3Kα inhibition

SummaryPIK3CA, which encodes the p110α subunit of PI3K, is frequently mutated and oncogenic in breast cancer. PI3Kα inhibitors are in clinical development and despite promising early clinical activity, intrinsic resistance is frequent among patients. We have previously reported that residual downstream mTORC1 activity upon treatment with PI3Kα inhibitors drives resistance to these agents. However, the mechanism underlying this phenotype is not fully understood. Here we show that in cancer cells resistant to PI3Kα inhibition, PDK1 blockade restores sensitivity to these therapies. SGK1, which is activated by PDK1, contributes to the maintenance of residual mTORC1 activity through direct phosphorylation and inhibition of TSC2. Targeting either PDK1 or SGK1 prevents mTORC1 activation, restoring the antitumoral effects of PI3Kα inhibition in resistant cells

Snow microstructure on sea ice: Importance for remote sensing applications

European Geosciences Union (EGU) General Assembly, 19-30 Apr 2021.-- 2 pagesSnow plays a key role in interpreting satellite remote sensing data from both active and passive sensors in the high Arctic and therefore impacts retrieved sea ice variables from these systems ( e.g., sea ice extent, thickness and age). Because there is high spatial and temporal variability in snow properties, this porous layer adds uncertainty to the interpretation of signals from spaceborne optical sensors, microwave radiometers, and radars (scatterometers, SAR, altimeters). We therefore need to improve our understanding of physical snow properties, including the snow specific surface area, snow wetness and the stratigraphy of the snowpack on different ages of sea ice in the high Arctic. The MOSAiC expedition provided a unique opportunity to deploy equivalent remote sensing sensors in-situ on the sea ice similar to those mounted on satellite platforms. To aid in the interpretation of the in situ remote sensing data collected, we used a micro computed tomography (micro-CT) device. This instrument was installed on board the Polarstern and was used to evaluate geometric and physical snow properties of in-situ snow samples. This allowed us to relate the snow samples directly to the data from the remote sensing instruments, with the goal of improving interpretation of satellite retrievals. Our data covers the full annual evolution of the snow cover properties on multiple ice types and ice topographies including level first-year (FYI), level multi-year ice (MYI) and ridges. First analysis of the data reveals possible uncertainties in the retrieved remote sensing data products related to previously unknown seasonal processes in the snowpack. For example, the refrozen porous summer ice surface, known as surface scattering layer, caused the formation of a hard layer at the multiyear ice/snow interface in the winter months, leading to significant differences in the snow stratigraphy and remote sensing signals from first-year ice, which has not experienced summer melt, and multiyear ice. Furthermore, liquid water dominates the extreme coarsening of snow grains in the summer months and in winter the temporally large temperature gradients caused strong metamorphism, leading to brine inclusions in the snowpack and large depth hoar structures, all this significantly influences the signal response of remote sensing instrumentsPeer reviewe

Leadership, Innovative Behavior and the Case of Innovative Climate—When the Mediator Becomes the Mediated

This study investigates how leadership, more precisely leader–member exchange (LMX), affects innovative behavior through an innovative climate as well as, indirectly, through organizational commitment and internal trust. A total of 1114 samples were collected from employees working in firms in Slovenia and Serbia. The quantitative data and the proposed model were analyzed with the partial least squares—SEM technique. The results indicate that an innovative climate is a mediator in the relationship between leadership and innovative behavior, and this relationship is also further mediated by internal trust and organizational commitment. These results reveal serial mediation or the complex role of an innovative climate in the process of influencing innovative work behavior. Implications for theory and recommendations for practice are discussed

Potentiometric stripping analysis of lead and cadmium leaching from dental prosthetic materials and teeth

Potentiometric stipping analysis (PSA) was applied for the determination of lead and cadmium leaching from dental prosthetic materials and teeth. The soluble lead content in finished dental implants was found to be much lower than that of the individual components used for their preparation. Cadmium was not detected in dental implants and materials under the defined conditions. The soluble lead and cadmium content of teeth was slightly lower than the lead and cadmium content in whole teeth (w/w) reported by other researchers, except in the case of a tooth with removed amalgam filling. The results of this work suggest that PSA may be a good method for lead and cadmium leaching studies for investigation of the biocompatibility of dental prosthetic materials

Procjena vijeka trajanja razvodnika snage temeljena na kriterijima mehanike loma

Dimensioning of pressure vessels can be done according to various criteria, the basic one being the safety against the fracture by splashing. In this paper two methods for this dimensioning procedure are presented. The first one is based on application of the classical mechanics while the second one uses the fracture mechanics principles. Both methods were applied for checking the exploitation properties and capability of a vapor distributor in a power plant. Based on the in-situ measured damages and calculations by both methods, it was concluded that the vapor distributor could be further used as a part of the boiler installation in the local power plant. The second criterion, based on the application of the fracture mechanics principles, provided more reliable results than the first one, based on the classical mechanics.Dimenzioniranje posuda pod tlakom može se vršiti prema različitim kriterijima, od kojih je jedan od osnovnih sigurnost protiv loma. U ovom radu su u tom smislu prezentirane dvije metode. Prva se bazira na primjeni klasične mehanike dok druga koristi principe mehanike loma. Obje metode su primijenjene za provjeru eksploatacijskih svojstava razvodnika snage u energetskom postrojenju. Na bazi in-situ izmjerenih oštećenja i proračuna po obje metode, zaključeno je da se razvodnik snage može i dalje koristiti kao dio kotlovske instalacije u lokalnoj termoelektrani. Drugi kriterij, baziran na principima mehanike loma, dao je pouzdanije rezultate nego prvi, baziran na klasičnoj mehanici

Qualification of the welding technology of the structural steel S355J2G3

© Published under licence by IOP Publishing Ltd. The selection procedure and qualification of the optimal welding technology for the structural steel S355J2G3 are presented in this paper. The considered steel is widely applied for manufacturing the supporting structures in various areas, especially in civil and mechanical engineering. It is delivered mainly in form of plates of various thicknesses and solid profiles of various diameters. Considering that welding is mostly used in manufacturing of structures, it is very important to be aware of possibilities for this steel welding, as well as of problems that may arise during that process. Here are presented: a calculation procedure of the base metal's weldability, selection of the filler metal and the welding technology, with results of experimental testing of the base metal and welded samples. The following experimental investigations were performed: tensile, bending and impact toughness test, metallographic investigations and hardness measurement. All the samples were cut out from the welded plates. Obtained results have shown that the structural steel S355J2G3 is suitable for welding, since there is no danger of appearance of cracks or other defects. With adequate choice of the welding technology the mechanical properties of the welded joint can be comparable to those of the base metal

Impact of the hard facing technology and the filler metal on tribological characteristics of the hard faced forging dies

© 2015, Strojarski Facultet. All rights reserved. The forging dies are parts, which are operating at elevated temperatures, while simultaneously subjected to variable loads that can be compressive - even impact and shear. Impact of the hard facing technology is very strong since varying of the hard facing parameters directly affects the output characteristics of the hard faced layers. The criterion for estimating that impact was based on results of performed tribological investigations. The tribological parameters that were monitored were the friction coefficient, the wear scar/trace width and the wear area of the hard faced layers, with the two different types of lubricants. Hard facing technology implied selection of the welding process, filler metals, preheating temperatures and other parameters of the hard facing process. The influence of the proposed hard facing technology was determined by monitoring hardness, microstructure and wear resistance of the executed joints after the hard facing and after tempering. The objective of this work was to establish the correlation between the selected hard facing technology, filler metals and applied heat treatment on mechanical and tribological characteristics of the executed hard faced layers

In-Situ Quantitative and Multiscale Structural Study of Starch-Based Biomaterials Immersed in Water

The behavior upon immersion in water of two types of starchy materials of biomedical relevance, amorphous potato starch and glycerol-plasticized potato starch, is analyzed in depth. Synchrotron X-ray scattering, specifically wide-angle X-ray scattering (WAXS), and magnetic resonance microimaging (MRμI) are used as very precise and nondestructive quantitative methods to monitor water transfers and structure changes in the samples, with refined spatial and kinetics results. The ingress of water in the cylinder-shaped samples can be inferred from both techniques, and from this, a diffusion mechanism is deduced for each sample type. Qualitatively, scattering and imaging give comparable results: plasticized samples are shown to behave close to a Fickian diffusion case, amorphous samples close to a case II. WAXS results also provide an in-depth knowledge of the crystalline structures associated to each step of the water ingress, and these are in turn correlated to water diffusion. To refine these observations, a recrystallized starch sample is also analyzed via WAXS. This study gives better insight into the structure of a material with a huge biomedical potential (as implants, for example), and for such applications, the behavior upon immersion in water is particularly relevant