Anotace témat disertačních prací doktorského studia pro obor Technologie makromolekulárních látek pro akademický rok 2010/2011

Transkript

1 Anotace témat disertačních prací doktorského studia pro obor Technologie makromolekulárních látek pro akademický rok 2010/ Téma/Topic: Phase separation of powder/binder feedstock during flow through testing mould for metal injection moulding Školitel/Tutor: doc. Ing. Berenika Hausnerová, Ph.D. Anotace/Annotation: The aim of a PhD topic is step by step description of the major quality influencing factor for metal injection moulding (MIM) phase separation. Phase separation might cause visual defects, porosity, warpage and cracks. After a theoretical definition of the phase separation, the design proposals for injection moulds, software simulations, optimization of injection moulding for various commercially available feedstock compositions should be given. Požadavky na studenta: Candidate should should have a MSc. degree in processing engineering; practical skills in inejction moulding, CATIA V5 and MoldFlow modeling desirable.. 1. R.M. German, "Powder Injection Moulding". 1st Edn, Metal Powder Industries Federation, Princeton, Téma/Topic: Development of the Binder System for Titanium Injection Moulding Compound Školitel/Tutor: doc. Ing. Berenika Hausnerová, Ph.D. hausnerova@ft.utb.cz Anotace/Annotation: The proposal concerns the development of the binder system for titanium alloy compounds with the aim of production on PIM parts for medical sector. PIM (Powder Injection Moulding) technology is a state-of-art process for making metallic and ceramic items using forming method for thermoplastics. This technique allows the large-number production of relatively small (corresponding to a weight of around 100 grams) parts of complex shapes with reduced cost and increased efficiency by avoiding the use of extra processes. The number of process variables is very large, and their correlations are only partially understood

2 Biocompatibility, corrosion resistance and lack of magnetism together with feasibility of PIM in production of small, very complex-shaped parts predestinate titanium-based PIM compounds (Ti-PIM) for the production of dental orthodontic brackets, cosmetic cases, aortic heart valves, implanted bone screws, endoscopic nozzles, surgical tools, etc. The major problem limiting a number of Ti-PIM applications in a medical sector consists in residual content of oxide and carbon governing the mechanical properties of the final sintered parts. Even if the most expensive, low O 2 and C content titanium powder is selected, each step of PIM process mixing with polymer binder, injection moulding, polymer removal and sintering introduces additional increase of these contaminants. The smallest oxygen increment achieved so far has been 0.04 wt.%. The oxidation during mixing can be partly avoided when using argon atmosphere, but such solution is economically ineffective in many cases. The proposed PhD topic is intended to develop polymer binder based on low-melting polymers to avoid titanium reaction with oxygen during mixing and moulding initiated by high temperature, and at the same time polymers, which decompose into a low carbon residua.. Požadavky na studenta: Candidate should should have a MSc. degree in metallurgy or chemical engineering; practical skills in metal sintering is desirable.. 1. R.M. German, "Powder Injection Moulding". 1st Edn, Metal Powder Industries Federation, Princeton, Téma/Topic: Rheological characterization of PIM feedstocks with the specific regard to wall-slip and powder-binder separation during moulding step Školitel/Tutor: doc. Ing. Berenika Hausnerová, Ph.D. hausnerova@ft.utb.cz Anotace/Annotation: Powder Injection Moulding (PIM) technology is a state-of-art process for making metallic and ceramic items using forming method for thermoplastics injection moulding. This technique allows the large-number production of relatively small (corresponding to a weight of around 100 grams) parts of complex shapes with reduced cost and increased efficiency by avoiding the use of extra processes. The number of process variables is very large, and their correlations are only partially understood. During the production of PIM-parts the powder is mixed with an organic (polymeric) binder into a homogeneous compound (feedstock). In the next step, the compound is formed by conventional thermoplastic injection moulding into the final shape. After accomplishing its primary role dispersion with powder - 2 -

3 into compound with a viscosity suitable for injection moulding - the binder is thermally or chemically removed (debinded) from the feedstock. Finally, the compact is sintered to obtain metallic or ceramic item of a density about 98% of the theoretical. Rheology plays a key role in the optimization of the injection moulding step in terms of both processing parameters and mould design. As the research in the PIM technology field is nowadays directed to micro-moulding ( PIM) due to the increased application potential in a medical sector, the demands on rheological investigation become more stringent. As the size of powder should be less than 1/20 of a smallest feature (i.e. less than 100 nm particle size for 2 m part), the feedstock design must rely on nanopowders. Due to high surface-to-volume ratio of nanopowder its loading level in a binder must be set very close to the maximum theoretically attainable, and therefore, mixing and moulding step will be a critical in terms of agglomeration and consequent feedstock inhomogeneity as well as risk of its separation connected with wall-slip during high shear rates during moulding. Capillary rheometry tests are currently realized as the best approach to predict the flow behaviour of PIM compounds, however, even the use of this type of instrument is complicated by several factors as the flow restrictions caused by instabilities or so called Serge-Silberberg effect, i.e. movement of particles from the capillary wall to the centre during flow, which achieves a great magnitude, and thus leads to an axial solids concentration gradient. Požadavky na uchazeče: MSc. degree in chemical or mechanical engineering; practical skills in injection moulding are desirable. 1. R.M. German, "Powder Injection Moulding". 1st Edn, Metal Powder Industries Federation, Princeton, Téma/Topic: In vitro testování vlivu pokročilých nanokompozitů pro hypertemickou léčbu rakoviny na buněčné modely Školitel/Tutor: prof. Ing. Petr Sáha, CSc. Konzultant/Consultant: Ing. Petr Humpolíček, Ph.D. saha@utb.cz Anotace/Annotation: Předmětem práce bude výzkum efektivnosti léčby rakoviny pomocí hypertemie za využití pokročilých nanokompozitů. In vitro testování bude probíhat za využití buněčných linií. Efektivita léčby bude pak testována pomocí stanovení cytotoxicity a molekulárně-genetických metod charakterizujících vliv na dědičnou informaci. Biomaterials and tissue engineering. Publisher: Berlin ; New York : Springer (2004) ISBN Hybrid nanocomposites for nanotechnology : electronic, optical, magnetic and biomedical applications. Publisher: New York : Springer (2008) ISBN

4 Cell Biology: A Laboratory Handbook, Four Volume Set. Publisher: Academic Press, 3 edition (July 18, 2005). ISBN-10: Culture of Animal Cells: A manual of Basic Technique. Publisher: Wiley-Liss; 5 edition (July 29, 2005) ISBN-10: Culture of Cells for Tissue Engineering. Publisher: Wiley-Liss; 1 edition (February 3, 2006) ISBN-10: Molecular Biology of the Cell. Publisher: Garland Science; 5 edition (2007) ISBN-10: Journal: Molecular Cell. ISSN: Journal: Journal of Biomaterials Science - Polymer edition. ISSN: Journal: Medicine. ISSN: Téma/Topic: Biomimetické polymerní systémy pro regenerační medicínu Školitel/Tutor: prof. Ing. Petr Sáha, CSc. Konzultant/Consultant: Ing. Petr Humpolíček, Ph.D. saha@utb.cz Anotace/Annotation: Předmětem práce bude příprava materiálů využitelných pro lékařské aplikace. Podstatnou částí bude následná úprava vlastností materiálů a testování jejich in vitro testování s pomocí alternativních buněčných modelů. Cílem práce pak bude vytvoření materiálu splňujícího nároky pro biomedicíncké aplikace a to především s ohledem na buněčnou interakci. Polymers for regenerative medicine. Publisher: Berlin ; New York : Springer, (2006) ISBN Biomedical technology and devices handbook. Publisher: Boca Raton : CRC Press, (2004) ISBN Cell Biology: A Laboratory Handbook, Four Volume Set. Publisher: Academic Press, 3 edition (July 18, 2005). ISBN-10: Culture of Animal Cells: A manual of Basic Technique. Publisher: Wiley-Liss; 5 edition (July 29, 2005) ISBN-10: Culture of Cells for Tissue Engineering. Publisher: Wiley-Liss; 1 edition (February 3, 2006) ISBN-10: Molecular Biology of the Cell. Publisher: Garland Science; 5 edition (2007) ISBN-10: Journal: Cell. ISSN: Journal: Biomaterials. ISSN: Journal: Journal of Biomaterials Applications. ISSN: Journal: Stem Cells and Development. ISSN: Téma/Topic: Aditivace polypropylénu za účelem optimalizace propustností plynů v extrudovaných biaxiálně orientovaných fóliích Školitel/Tutor: prof. Ing. Petr Sáha, CSc. Konzultant/Consultant: Ing. Tomáš Sedláček, Ph.D

5 Anotace/Annotation: Popis vlivů aditiv, vhodných pro plnění extrudovaných tenkých biaxiálně orientovaných fólií, za účelem optimalizace propustnosti vybraných plynů. Příprava finálních fólií bude zacílena na oblast obalovin ve zdravotnictví a potravinářství. Připravené fólie budou průběžně srovnávány s dosavadně komerčně dostupnými produkty. 1 - Functional Fillers for Plastics; Editor: Prof. Dr. Marino Xanthos, 2005 WILEY-VCH Verlag 2 - ADDITIVES IN POLYMERS, Industrial Analysis and Applications, Jan C.J. Bart, John Wiley & Sons 7. Téma/Topic: Modifikace antibakteriálních vlastností extrudovaných profilů s aplikací ve zdravotnictví a potravinářství Školitel/Tutor: prof. Ing. Petr Sáha, CSc. Konzultant/Consultant: Ing. Tomáš Sedláček, Ph.D. saha@utb.cz, sedlacek@ft.utb.cz Anotace/Annotation: Budou sledovány a optimalizovány bioaktivní vlastnosti extrudovaných polymerních systemů pomocí aditiv, výsledné morfologie polymerních směsí a povrchových modifikací. Získané výstupy budou v maximální možné míře použity pro modifikaci stávajících polymerních produktů používaných ve zdravotnictví. 1 - Medical Implications of Biofilms, MICHAEL WILSON, Cambridge University 2 - Additive Migration from Plastics into Foods A Guide for Analytical Chemists, T.R. Crompton, Rapra Technology LimitedFoods 8. Téma/Topic: Preparation and modifications of biodegradable polyesters for medical applications Školitel/Tutor: prof. Ing. Petr Sáha, CSc. Konzultant/Consultant: Ing. Vladimír Sedlařík, Ph.D. saha@utb.cz, sedlarik@ft.utb.cz Anotace/Annotation: The proposed theme for PhD study is focused on both synthesis and subsequent tailoring of biodegradable polyesters and it is a follow-up to research projects, which are carried out at Polymer Centre. The direction of the research will be aimed at preparation of materials for medical applications. Furthermore, cooperation with practical sphere is expected. The potential PhD student will extend his/her knowledge in the area of chemistry (organic, analytical, and physical), biology and material science during the PhD studies. A potential applicant is required to be: - 5 -

6 graduated in polymer science or in a similar field; well English speaking and writing, keen on research work. 1. Ramakrishna, S., Huang, Z.M., Kumar, G.V., Batchelor, A.W., Mayer, J. An introduction to biocomposites, Imperial College Press, London Wong, J, Y., Brozino J.D. Biomaterials, CRC press, Boca Raton Časopisecké a knižní zdroje dostupné prostřednictvím knihovny UTB ve Zlíně 9. Téma/Topic: Magneto-polymeric materials: structure and properties Školitel/Tutor: doc. Ing. Natalia Kazantseva, Ph.D. Konzultant/Consultant: doc. Ing. Jarmila Vilčáková, Ph.D., Ing. Robert Moučka, Ph.D. kazantseva@ft.utb.cz, vilcakova@ft.utb.cz, moucka@ft.utb.cz Anotace/Annotation: Magnetic composite materials, produced by embedding ferroand ferrimagnetic particles in a nonmagnetic matrix, have a significant advantage over bulk magnetic materials (metallic or sintered ferrite) due to its higher resistivity, low density, chemical stability and processability. Moreover, this is the fact that as the complex magnetic permeability and permittivity are structure- sensitive, by changing the concentration, shape, and size of filler, as well as in the case of the microstructure of the composite, it is possible to manipulate the electromagnetic properties of the material. For these friendly material handling properties, magnetic composites have many useful applications such as magnetic substrates for microwave antennas, microwave inductors, electromagnetic wave absorbers and also the novel material will be an encouraging tool for the treatment of deep-sited tumours on human body by introducing the technique of hyperthermia. Požadavky na studenta: technical science (solid-state physics, physics of magnetism, polymers, materials engineering, and electronics) 1. J. Smith, H. P. J. Wijn, Ferrites, Philips Technical Library, Eindhoven, P. Hippel, Dielectric Materials and Applications, New-York, Willey, Smith R. A., Semiconductors, Cambridge At The University Press, G. Gurevich and G. A. Melkov, Magnetization Oscillation and Waves, CRC Press, Inc.,1996. S. Chikazumi, Physics of Ferromagnetism, New York: Oxford University Press, David Sellmyer, Ralf Sellmyer, Advanced Magnetic Nanostructures, Springer Science+Business Media, Inc., Handbook of Conducting Polymers, Marcel Dekker, New York,

7 10. Téma/Topic: Dielektrická spektroskopie polymerních nanokompozitů Školitel/Tutor: doc. Ing. Jarmila Vilčáková, Ph.D. Konzultant/Consultant: Ing. Robert Moučka, Ph.D. Anotace/Annotation: Disertační práce se zabývá studiem dielektrické spektroskopie hybridních polymerních nanokompozitů na bázi uhlíkových nanotub, uhlíkových nanovláken a nanočástic. Cílem práce je návrh a příprava nové generace hybridních nanomateriálů schopných řízeným způsobem absorbovat elektromagnetické záření především v mikrovlnné oblasti. (Práce bude vypracována ve spolupráci s Institutem Radioinženýrství a Elektroniky v Moskvě, Ústavem makromolekulární chemie AV ČR v Praze a Ústavem Polymérov SAV v Bratislavě). Požadavky na uchazeče: Absolvent technického směru v oblasti chemie, fyzika, materiálové inženýrství a příbuzných inženýrských disciplin. 1. Ajayan, M., Schadler, L.S., Braun, V.,: Nanocomposite Science and Technology, WILEY-VCH, (2006). 2. Chen, L. F., Ong, C. K., Neo, C. P., Varadan, V. V., Varadan, V. K.: Microwave Electronics, WILEY-VCH, Weinheim, (2005). 11. Téma/Topic: Electromagnetic properties of polymer composites Školitel/Tutor: doc. Ing. Jarmila Vilčáková, Ph.D., Konzultant/Consultant: doc. Ing. Natalia Kazantseva, Ph.D. vilcakova@ft.utb.cz, kazantseva@ft.utb.cz Anotace/Annotation: Doctoral thesis deals with the study of polymer composites with electric and magnetic fillers. The aim of the work is to prepare polymer system with high values of dielectric and magnetic losses, in which by the effect of alternating electromagnetic field heat is intensively generated. The applications of such polymer systems could comprise e.g. mediators for the local magnetic hyperthermia, a noninvasive treatment of malignant diseases. (Work will engage cooperation with Russian Research Centre for Radiology and Surgical Technologies, Federal Agency of High Medical Care Technology, St. Petersburg, RF, Institute macromolecular chemistry in Prague, Academy of Science of CZ and Polymer Institute in Bratislava, Slovak Academy of Science). Požadavky na uchazeče: graduated in technical science (chemistry, physics, biophysics, material engineering, polymer science )

8 1. Clayton R. Paul: Introduction to Electromagnetic Compatibility, Second edition, WILEY-VCH, (2006). 2. Ajayan, M., Schadler, L.S., Braun, V.,: Nanocomposite Science and Technology, WILEY-VCH, (2006). 3. A.J. Baden Fuller: Ferrites at microwaves frequencies. 12. Téma/Topic: Development and characterization of novel polymer composites with entangled carbon nanotubes networks Školitel/Tutor: doc. Ing. Petr Slobodian, Ph.D. Anotace/Annotation: Today s technology progress relies heavily on the use of materials that allow for achieving advanced structural and functional capabilities. In this respect carbon nanotubes (CNT) polymer composites have the potential for becoming advanced material for large mechanical and thermoelectric loadings. If the unique properties of CNT could be employed in composites, we could have materials that are stronger, stiffer, more thermally and electrically conductive that anything what is used today. CNT are stronger than steel, lighter than aluminum, and more conductive than copper. The general vision about revolutionary CNT polymer composites presents both great potential and great challenges for years to come. Consequently, being aware of the progression need as well as vast application possibilities, we will try an unconventional method to fabricate dense polymer composites with preformed entangled porous CNT network. This network should transfer maximally unique CNT properties into novel composites and bring substantial improvements in structural strength, weight savings and energy consumption in aerospace, automotive and actuator industries and biomedical engineering. 1. Harris P.J.F., Carbon Nanotube Science Synthesis, Properties and Applications, Cambridge University Press, Yeh C.S., A study of nanostructure and properties of mixed nanotube buckypaper materials: Fabrication, Process, modelling, characterization and property, Ph.D. Thesis, The Florida State University (2007). 3. Wang D, Song P, Liu C, Wu W, Fan S, Highly oriented carbon nanotube papers made of aligned carbon nanotubes, Nanotechnology 19 (2008) Whitby R.L.D., Fukuda T., Maekawa T., James S.L., Mikhalovsky S.V., Geometric control and tuneable pore size distribution of buckypaper and buckydiscs, Carbon 46(6) (2008) Téma/Topic: Tenké polymerní kompozitní vrstvy Školitel/Tutor: doc. Ing. et Ing. Ivo Kuřitka, Ph.D. et Ph.D. kuritka@ft.utb.cz - 8 -

9 Anotace/Annotation:Cílem práce je příprava a charakterizace tenkých vrstev z nových hybridních nanokompozitů pro pokročilé aplikace v senzorice. Práce bude zaměřena na vlastnosti elektricky vodivých polymerů ve směsích s molekulárními látkami a nanočásticemi. Bude studován vliv dopantů na funkční vlastnosti a stabilitu systémů. Analytická část studie využije dostupné spektroskopické a mikroskopické metody. Požadavky na studenta: absolvent technického nebo přírodovědného oboru v oblasti chemie, fyziky a příbuzných inženýrských oborů SKOTHEIM, T.A.; REYNOLDS, J.R. Conjugated polymers : theory, synthesis, properties, and characterization. 3rd. Boca Raton ; London: CRC, Taylor & Francis Group, různé str. ISBN GOLDSTEIN, J.I. Scanning electron microscopy and X-ray microanalysis. 3rd. New York: Kluwer, xix, 689 s. ISBN Téma/Topic: Víceměřítkové hierarchické kompozitní systémy Školitel/Tutor: doc. Ing. et Ing. Ivo Kuřitka, Ph.D. et Ph.D. kuritka@ft.utb.cz Anotace/Annotation: Cílem práce je příprava a charakterizace plniv a polymerních kompozitů s aplikačním potenciálem pro přípravu speciálních kompozitních materiálů. Struktura materiálů bude hierarchicky organizována v různém měřítku. Syntéza plniv se zaměří na reakce v kapalinách a suspenzích. Analytická část studie využije dostupné spektroskopické, mikroskopické a rheologické metody. Požadavky na uchazeče:absolvent technického nebo přírodovědného oboru v oblasti chemie, fyziky a příbuzných inženýrských oborů LOUPY, A. Microwaves in organic synthesis. 2nd, completely rev. and enlarged edition.. Weinheim: Wiley-VCH, v. (1007 p.). ISBN GOLDSTEIN, J.I. Scanning electron microscopy and X-ray microanalysis. 3rd. New York: Kluwer, xix, 689 s. ISBN HAVRILIAK, S.; HAVRILIAK, S.J. Dielectric and Mechanical Relaxation in Materials : Analysis, Interpretation, and Application to Polymers. Munich: Hanser Publ., s. ISBN Téma/Topic: Preparation and characterization of anti-coagulant surfaces Školitel/Tutor: doc. Ing. Marián Lehocký, Ph.D. lehocky@ft.utb.cz - 9 -

10 Anotace/Annotation: The goal of the project will be preparation and characterization of intelligent anti-coagulant surfaces with prospective application for storage, transport or manipulation with blood and its components. We suppose to use commercially available synthetic polymer materials which will be modified and consequently coated with an intelligent layer of anti coagulant agent. The interaction with blood in general and with blood platelets in particular will be thoroughly studied. Joist, J. H.; Pennington D. C.; Platelet reactions with artificial surfaces. Transactions- American Society for Artificial Internal Organs 33, 341 (1987). Chu, P. K.; Chen, J. Y.; Wang, L. P.; Huang, N.; Plasma- surface modification of biomaterials. Material Science Engineering R 36, 143 (2002). Inagaki, N.; Narushim, K.; Tuchida, N.; Miyazaki, K.; Surface characterization of plasma-modified poly(ethylene terephthalate) film surfaces. Journal of Polymer Science, Part B: Polymer Physics 42, 3727 (2004). Busscher, H. J.; van Pelt, A. W. J.; de Boer, P.; de Jang, H. P.; Arends, J.; The effect of surface roughening of polymers on measured contact angles of liquids. Journal of Colloid Surface 9, 319 (1984). Lee, J. H.; Lee, H. B.; Platelet adhesion on to wettability gradient surfaces in the absence and presence of plasma proteins. Journal of Biomedical Materiál Research 41, 304 (1998). Mooradian, D. L.; Trescony, P.; Keeney, K.; Furcht, L. T.; Effect of glos discharge surface modiffcation of plasma TFE vascular graft material on fbronectin and laminin retention and endothelial cell adhesion. Journal of Surgery Research 53, 74 (1992). Ratner, B. D.; Hoffman, A. S.; Schoen, F. J.; Lemons, J. E.; Biomaterials Science (Academic Press, San Diego, 1996). 16. Téma/Topic: Vrstevnatá plniva pro hybridní polymerní systémy Školitel/Tutor: doc. Ing. Jiří Maláč, CSc. Konzultant/Consultant: Ing. Alena Kalendová, Ph.D. malac@ft.utb.cz, kalendova@ft.utb.cz Anotace/Annotation: Vrstevnaté minerály se jeví jako vhodný zdroj nanočástic pro polymerní systémy. Zvláště důležitým faktorem v této oblasti výzkumu je vhodná úprava plniva, která umožňuje následné rozlístkování (exfoliaci) plniva při zpracování. Nedílnou součástí je studium vlastností získaných hybridních systémů. Výsledky práce by mohly najít uplatnění v praxi. 17. Téma/Topic: Dynamicko-mechanické a mechanicko-fyzikální vlastnosti kaučukových směsí Školitel/Tutor: doc. Ing. Jiří Maláč, CSc. Konzultant/Consultant: Ing. Petr Konečný, Ph.D. malac@ft.utb.cz, konecny@ft.utb.cz Anotace/Annotation: The focus will be on mixing optimization using various mixing devices. Structure will be observed by optical microscopy, SEM and XRD

11 Mechanical properties will be compared with the structure. Elastic properties will be balanced with high temperature resistance. New cross-linking methods will be explored. 18. Téma/Topic: New polyolefin polymer blends and nanocomposites for automotive industry Školitel/Tutor: doc. Ing. Petr Svoboda, Ph.D. Anotace/Annotation: The focus will be on mixing optimization using various mixing devices. Structure will be observed by optical microscopy, SEM and XRD. Mechanical properties will be compared with the structure. Elastic properties will be balanced with high temperature resistance. New cross-linking methods will be explored. 19. Téma/Topic: Zpracování, struktura a vlastnosti poly-4-methyl-1-pentenu Školitel/Tutor: doc. Ing. Roman Čermák, Ph.D. Konzultant/Consultant: Ing. Lubomír Beníček, Ph.D. cermak@ft.utb.cz, benicek@ft.utb.cz Anotace/Annotation: Navržené doktorské téma se bude zabývat zpracováním, fázovými transformacemi a vlastnostmi poly-4-methyl-1-pentenu. Tento materiál si zasluhuje větší pozornost nejen díky zajímavému polymorfnímu chování, ale taktéž značnému aplikačnímu potenciálu v medicínských aplikacích. Výsledkem bude lepší pochopení vzájemných vztahů mezi zpracováním, polymorfní strukturou a finálními vlastnostmi, což napomůže dalšímu rozšíření aplikačního potenciálu tohoto materiálu. 20. Téma/Topic: Polyolefins/natural fillers composites Školitel/Tutor: doc. Ing. Roman Čermák, Ph.D. cermak@ft.utb.cz Anotace/Annotation: Combination of commodity polyolefins with natural fillers can bring material with favourable price-to-performance ratio. Unfortunately, the combination of cellulose fibres with polyolefins is complicated by their dissimilar chemical nature, which leads to a high interphase tension and a low interphase adhesion. Common way to improve the problem is based on chemical modification of polyolefin matrix. This work will be focused on the application of treated, hydrophobic cellulose fibres into polyolefin matrix, which can be a smart alternative way to common approach