A novel framework for fluid/structure interaction in rapid subjectspecific simulations of blood flow in coronary artery bifurcations

Background/Aim. Practical difficulties, particularly long model development time, have limited the types and applicability of computational fluid dynamics simulations in numerical modeling of blood flow in serial manner. In these simulations, the most revealing flow parameters are the endothelial shear stress distribution and oscillatory shear index. The aim of this study was analyze their role in the diagnosis of the occurrence and prognosis of plaque development in coronary artery bifurcations. Methods. We developed a novel modeling technique for rapid cardiovascular hemodynamic simulations taking into account interactions between fluid domain (blood) and solid domain (artery wall). Two numerical models that represent the observed subdomains of an arbitrary patient-specific coronary artery bifurcation were created using multi-slice computed tomography (MSCT) coronagraphy and ultrasound measurements of blood velocity. Coronary flow using an in-house finite element solver PAK-FS was solved. Results. Overall behavior of coronary artery bifurcation during one cardiac cycle is described by: velocity, pressure, endothelial shear stress, oscillatory shear index, stress in arterial wall and nodal displacements. The places where (a) endothelial shear stress is less than 1.5, and (b) oscillatory shear index is very small (close or equal to 0) are prone to plaque genesis. Conclusion. Finite element simulation of fluid-structure interaction was used to investigate patient-specific flow dynamics and wall mechanics at coronary artery bifurcations. Simulation model revealed that lateral walls of the main branch and lateral walls distal to the carina are exposed to low endothelial shear stress which is a predilection site for development of atherosclerosis. This conclusion is confirmed by the low values of oscillatory shear index in those places

Prilog određivanju ekonomičnosti trešenja višanja i šljiva

Picking sour cherries and plums, compared to other orchard maintenance operations, like cutting, fertilizing and protecting fruit, requires the engagement of a large labor force, much time, and carries high costs, that influence the price of the product heavily. This paper analyzes the possibilities related to the use of a mechanized way of picking, i.e. shaking, showing the advantages of using shakers. Besides the analysis of the shake-off time, this paper also presents the indicators of economic advantages of the application of a tractor-driven fruit shaker for a certain fruit plantation over hand picking. Research has undoubtedly shown the advantage of using shaker over the manual way of picking of fruit.Ubiranje višanja i šljiva u poređenju sa ostalim operacijama obrade voćnjaka, orezivanja, đubrenja i zaštite voćka zahteva veliko angažovanje radne snage, dugačak vremenski period, odnosno visoke troškove koji se odražavaju i na cenu proizvoda. U radu je analizirana mogućnost primene mehanizovanog načina ubiranja, otresanjem, uz obrazloženje prednosti primene tresača. Osim analize vremena otresanja dati su i pokazatelji ekonomske prednosti primene konkretnog traktorskog tresača voća za određenu plantažu voća u odnosu na ručno branje. Istraživanja su ukazala na prednosti primene tresača u odnosu na ručno branje plodova

Operativna gotovost setvospremača kao kriterijum uspešnosti održavanja

In this paper is analsed seed bed cultivator editing maintenance as well as their operational readiness as criteria quality of successful for prophylaxislz maintenance. It is refere system of maintenance and energy of system as well as their adventure and defaultes. Research was escorted on the farm. Results was presented ans analysed in this paper.U radu se analizira korektivno održavanje setvospremača, odnosno njegova operativna gotovost kao merilo kvaliteta uspešnosti preventivnog održavanja.Razmatrani su sistemi održavanja i efektivnost sistema kao i njihove prednosti i nedostaci. Istraživanje je vršeno na jednom poljoprivrednom imanju, a rezultati su prezentovani i analizirani u radu

Operativna gotovost hidrauličnog podsistema agregata traktor-setvospremač

The paper consist specifics relating to the operation and maintenance of the hydraulic sub-aggregates tractor-cultivator. As the works in the seasonal character of agriculture and must be done in strictly defined time intervals, any notice element aggregates tractor-cultivator, may bring into question the performance of primary processing soil and great material losses. Therefore, the aggregate of the tractorcultivator requires very high reliability. The paper discusses the operational readiness of tractors as a measure of the effectiveness and quality of its maintenance. Also in the paper are the results of the research on the availability of aggregate tractor- cultivator on one agricultural good.U radu su date specifičnosti koje se odnose na eksploataciju i održavanje hidrauličnog podsistema agregata traktor-setvospremač. Kako su radovi u poljoprivredi sezonskog karaktera i moraju se obaviti u strogo termirinam vremenskim intervalima, to bilo koji otkaz elementa agregata traktor-setvospreemač, može dovesti u pitanje obavljanje dopunske obrade zemljišta, odnosno do velikih materijalnih gubitaka. Zbog toga se od agregata traktor-setvospremač zahteva i vrlo visoka operativna gotovost. U radu je razmatrana operativna gotovost kao merilo efektivnosti traktora i setvospremača, odnosno kvaliteta njihovog održavanja. Takođe u radu su dati rezultati istraživanja operativne gotovosti agregata traktor-setvospremač na jednom poljoprivrednom dobru

Modeling of thermoelectric module operation in inhomogeneous transient temperature field using finite element method

This paper is the result of research and operation modeling of the new systems for cooling of cutting tools based on thermoelectric module. A copper inlay with thermoelectric module on the back side was added to a standard turning tool for metal processing. For modeling and simulating the operation of thermoelectric module, finite element method was used as a method for successful solving the problems of inhomogeneous transient temperature field on the cutting tip of lathe knives. Developed mathematical model is implemented in the software package PAK-T through which numerical results are obtained. Experimental research was done in different conditions of thermoelectric module operation. Cooling of the hot module side was done by a heat exchanger based on fluid using automatic temperature regulator. After the calculation is done, numerical results are in good agreement with experimental. It can be concluded that developed mathe-matical model can be used successfully for modeling of cooling of cutting tools

Выставочное оборудование экспозиции «Томск: пейзаж после битвы» краеведческого музея г. Томска

Объектом исследования является разработка выставочного оборудования и его размещение в выставочных залах Томского краеведческого музея. Целью работы является проектирование выставочного оборудования, отвечающего требованиям задания, выданного С.В. Перехожевым, руководителем проекта "Томск: пейзаж после битвы".The object of the study is the development of exhibition equipment and its placement in the exhibition halls of the Tomsk Local History Museum. The aim of the work is to design exhibition equipment meeting the requirements of the assignment issued by S.V. Perekhozhev, head of the project "Tomsk: landscape after the battle.

Capability of exopolysaccharide-producing Lactobacillus paraplantarum BGCG11 and its non-producing isogenic strain NB1, to counteract the effect of enteropathogens upon the epithelial cell line HT29-MTX

The putative protective role of the exopolysaccharide (EPS)-producing Lactobacillus paraplantarum BGCG11, and its non-EPS-producing isogenic strain NB1, was tested upon HT29-MTX monolayers challenged with seven opportunistic pathogens. The probiotic strain Lactobacillus rhamnosus LMG18243 (GG) was used as a reference bacterium. Tested lactobacilli were able to efficiently reduce the attachment to HT29-MTX of most pathogens. Lb. paraplantarum NB1 and Lb. rhamnosus GG were more efficient reducing the adhesion of Clostridium difficile or Yersinia enterocolitica than Lb. paraplantarum BGCG11, while strain BGCG11 reduced, to a greater extent, the adhesion of Escherichia coli and Listeria monocytogenes. The detachment and cell lysis of HT29-MTX monolayers in the presence of pathogens alone and co-incubated with lactobacilli or purified EPS was followed. L. monocytogenes induced the strongest cell detachment among the seven tested pathogens and this effect was prevented by addition of purified EPS-CG11. The results suggest that this EPS could be an effective macromolecule in protection of HT29-MTX cells from the pathogen-induced lysis. Regarding innate intestinal barrier, the presence of C. difficile induced the highest IL-8 production in HT29-MTX cells and this capability was reinforced by the co-incubation with Lb. paraplantarum NB1 and Lb. rhamnosus GG. However, the increase in IL-8 production was not noticed when C. difficile was co-incubated with EPS-producing Lb. paraplantarum BGCG11 strain or its purified EPS-CG11 polymer, thus indicating that the polymer could hinder the contact of bacteria with the intestinal epithelium. The measurement of mucus secreted by HT29-MTX and the expression of muc1, muc2, muc3B and muc5AC genes in the presence of pathogens and lactobacilli suggested that all lactobacilli strains are weak >co-adjuvants> helping some pathogens to slightly increase the secretion of mucus by HT29-MTX, while purified EPS-CG11 did not induce mucus secretion. Taking altogether, Lb. paraplantarum BGCG11 could act towards the reinforcement of the innate mucosal barrier through the synthesis of a physical-protective EPS layer which could make difficult the contact of the pathogens with the epithelial cells. © 2015 Elsevier Ltd.This work was financed by the Spanish Ministry of Economy and Competiveness (MINECO) and FEDER funds (European Union) through the project AGL2012-33278, as well as by the Ministry of Education, Science and Technological Development of the Republic of Serbia grant No. 173019. The bilateral collaboration project AIB2010SE-00386 between Spain and the Republic of Serbia allowed the mobility of personnel between both institutions. C. Hidalgo-Cantabrana acknowledges his FPI pre-doctoral fellowship to MINECO (BES-2010-038270).Peer Reviewe

Cytotoxicity investigation of a new hydroxyapatite scaffold with improved structural design

Introduction Biodegradable porous scaffolds are found to be very promising bone substitutes, acting as a temporary physical support to guide new tissue regeneration, until the entire scaffold is totally degraded and replaced by the new tissue. Objective The aim of this study was to investigate cytotoxicity of a synthesized calcium hydroxyapatite-based scaffold, named ALBO-OS, with high porosity and optimal topology. Methods The ALBO-OS scaffold was synthesized by the method of polymer foam template. The analysis of pore geometry and scaffold wallstopography was made by scanning electron microscope (SEM). The biological investigations assumed the examinations of ALBO-OS cytotoxicity to mouse L929 fibroblasts, using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromidefor (MU) and lactate dehydrogenase (LDH) tests and inverse phase microscopy. Results The SEM analysis showed high porosity with fair pore distribution and interesting morphology from the biological standpoint. The biological investigations showed that the material is not cytotoxic to L929 cells. Comparison of ALBO-OS with Bio-Oss, as the global gold standard as a bone substitute, showed similar results in MTT test, while LDH test showed significantly higher rate of cell multiplication with ALBO-OS. Conclusion The scaffold design from the aspect of pore size, distribution, and topology seems to be very convenient for cell adhesion and occupation, which makes it a promising material as a bone substitute. The results of biological assays proved that ALBO-OS is not cytotoxic for L929 fibroblasts. In comparison with Bio-Oss, similar or even better results were obtained