Solving the Problem of Friction and Wear in Auxiliary Devices of Internal Combustion Engines on the Example of Reciprocating Air Compressor for Vehicles

Using vehicles and other mobile systems to transport passengers and goods, approximately 25% of Europe\u27s greenhouse gases are generated. At the same time, many research papers, published by researchers and students, promote the use of electric vehicles as zero-emission vehicles. Given that, more broadly, the emission of electric vehicles is higher, especially in countries where electricity is obtained by burning coal, the use of internal-combustion engines is still dominant. There are other reasons for using an internal-combustion engine, such as already developed pumping station infrastructure, which is not the case when recharging electric vehicles. Improvements in engine design contribute to meet the regulations relating to the fuel consumption and toxic gas emissions. This refers to the use of alternative fuels, improving the combustion process, and increasing efficiency (efficiency coefficient) by reducing losses. The research is focused on the problem of friction and wear in internal combustion engines and reciprocating air compressors, as auxiliary devices on engines. For that purpose, construction of the reciprocating air compressor in motor vehicles was redesigned. The paper presents the characteristic test results of material used to strengthen liner of the aluminum cylinder. Specifically, a method for testing the performance characteristics of a single-cylinder reciprocating compressor inside of an experimental installation for compressed air supply has also been proposed

Correlation between Emission and Combustion Characteristics with the Compression Ratio and Fuel Injection Timing in Tribologically Optimized Diesel Engine

Diesel engines are economical thanks to their combustion process characteristics, which is why they have a high noise emission level as well as exhaust emissions of nitrogen oxide and particulate matters. By continuously changing the value of compression ratio, it is possible to control the power and emissions. Implementation of variable compression ratio has many benefits, such as being able to work with different types of fuel. In this way, it is possible to optimize the combustion process for operation with minimum fuel consumption and emission generation, so that diesel engines can be applied to the framework of future hybrid vehicle concepts, and so forth. As far as the crucial objective of the manuscript is concerned, experimental diesel engine investigation was performed on a roller test-bench by using zero-dimensional computer model (specifically AVL IndiCom Indicate Software). Engine indication was executed with the factory compression ratio value and with three lower values. During our examination, the change in the compression ratio value was achieved by changing the volume of a combustion chamber at a piston-bowl. The results of laboratory research on the experimental engine are presented in the paper when discussing a series of specific parameters (characteristics), such as compression ratio, fuel injection timing, engine speed, as well as load influence on combustion process and exhaust emissions

Tribological Assessment of Aluminum Cylinder Material for Piston Compressors in Trucks and Buses Brake Systems

Applying new technologies to reduce friction and wear in vehicles and equipment can minimize mechanical losses. This reduces power loss in internal combustion engines and reduces fuel consumption and emissions. Consumption of fuel energy can be reduced by the use of light metals, for example aluminum alloy, to produce vehicles and their aggregates and parts. In this case, the problem is poor tribological properties of those light weight metals, as well as the lower strength compared to the cast iron construction. For tribology research purposes, the contact surface of the aluminum cylinder of an experimental piston air compressor is reinforced with inserts of cast iron. The results of tribology research of the composite material are presented in the paper, explaining how parameters such as the sliding speed, contact time and contact area influence friction and wear of the material in relative tribological contacts, under constant normal force. The test procedures were performed on the ball-on-plate CSM® nanotribometer, in linear reciprocating sliding conditions with no lubricant. Material composition of the samples was determined using the Energy-Dispersive Spectroscopy. All measurements were realized at the Faculty of Engineering, University of Kragujevac

Correlation of Cardio-Ankle Vascular Index, Ten-Year Risk Assessment and Other Atherosclerosis Risk Factors

The aim of the study was to assess correlation of atherosclerosis severity as determined by two different methods of screening for atherosclerosis: (A) measurement of the cardio-ankle vascular index-CAVI by use of the VaseraVS-1500 vascular screening device, and (B) Framingham scale scoring. 52 subjects (28 male and 24 female) were enrolled in the study. Classification of study subjects into four quartiles based on theoretically calculated 10-year risk according to Framingham scale (medians:1%, 3%, 4% and 15%) confirmed the risk increase to be associated with a statistically significant increase in CAVI, age and total cholesterol, and a statistically significant decrease in HDL-cholesterol (p<0.001 all). Spearman correlation coefficients showed a statistically significant correlation of 10-year risk with CAVI (p=0.0242; r=0.4494). Study results suggested that simultaneous determination of CAVI and 10-year risk might prove justified. They are not contradictory, the more so, these two parameters showed a significant positive correlation. This test panel yields comprehensible, implying all the possible consequences and highly motivating information that may stimulate the person for lifestyle modification

Correlation of Cardio-Ankle Vascular Index, Ten-Year Risk Assessment and Other Atherosclerosis Risk Factors

The aim of the study was to assess correlation of atherosclerosis severity as determined by two different methods of screening for atherosclerosis: (A) measurement of the cardio-ankle vascular index-CAVI by use of the VaseraVS-1500 vascular screening device, and (B) Framingham scale scoring. 52 subjects (28 male and 24 female) were enrolled in the study. Classification of study subjects into four quartiles based on theoretically calculated 10-year risk according to Framingham scale (medians:1%, 3%, 4% and 15%) confirmed the risk increase to be associated with a statistically significant increase in CAVI, age and total cholesterol, and a statistically significant decrease in HDL-cholesterol (p<0.001 all). Spearman correlation coefficients showed a statistically significant correlation of 10-year risk with CAVI (p=0.0242; r=0.4494). Study results suggested that simultaneous determination of CAVI and 10-year risk might prove justified. They are not contradictory, the more so, these two parameters showed a significant positive correlation. This test panel yields comprehensible, implying all the possible consequences and highly motivating information that may stimulate the person for lifestyle modification

THE IMPORTANCE OF THE MANAGEMENT COMPANY BY USING THE INTERNATIONAL ACCOUNTING STANDARDS

Managing the company requires a higher degree of standardization of processes, decision-making, decisionmaking, application of standard operating methods in companies, the use of international accounting standards, the standard of international financial reporting, and many other forms of business that can improve business operations and manage the company. There are numerous advantages for the top management of companies especially for those who have decided to apply the International Accounting Standards in everyday business in the accounting and financial sector of enterprises primarily, and then in other parts of the company. Their implementation allows for realistic financial reporting, which is extremely important for making a timely decision regarding strategic decision-making in an enterprise. This is particularly true for countries in transition, as well as for those countries that have not applied more widely to international accounting standards in regular and continuous business. The application of international accounting standards as well as the application of international financial reporting standards can lead to positive results and the enterprise can realize multiple benefits, especially if the company fully applies fair reporting in its business to top management but also towards the owners of the company or the founders of the compan

Expression of bone morphogenetic protein -2 and -7 during experimental inflammatory bowel disease

SAŽETAK. Cilj: Za koštane morfogenetske proteine -2 i -7 pokazano je da osim snažnog osteoinduktivnog svojstva imaju važnu ulogu u razvoju i cijeljenju različitih neskeletnih tkiva i organa. Svrha ovog rada je ispitati ekspresiju BMP-2 i BMP-7 tijekom upalne bolesti crijeva u štakora, te učinak dvotjednog liječenja sa BMP-7 na cijeljenje tkiva kolona i ekspresiju ovih morfogenetskih proteina. Metode: Eksperimentalni kolitis izazvan je primjenom klizme koja sadrži 2,4,6-trinitrobenzensulfoničnu kiselinu (TNBS) i etanol. Na uzorcima crijeva pratili smo makroskopske i mikroskopske promjene koje se zbivaju tijekom akutne i kronične faze kolitisa, te nakon i.v. primjene BMP-7. Metodom imunohistokemije i lančane reakcije polimeraze pratili smo izražaj BMP-2 i -7. Rezultati: Imunohistokemijska i RT-PCR analiza pokazala je ekspresiju BMP-2 i -7 tijekom akutne i kronične faze upalne bolesti crijeva. U akutnoj fazi kolitisa BMP-2 i -7 prisutni su u području ulkusa, a u kroničnoj fazi BMP-7 pozitivno bojanje prisutno je u kolonocitima uzduž kripti kolona, dok je BMP-2 pozitivno bojanje u kolonocitima površnog epitela te između kripta. Specifično bojanje na BMP-7 kao i ekspresija mRNA za BMP-7 na uzorcima crijeva životinja liječenim sa BMP-7 pokazuje smanjenje prisustva BMP-7, a pojačano bojanje i ekspresiju mRNA za BMP-2. Zaključak: Sistemska primjena koštanog morfogenetskog proteina-7 smanjuje makroskopsko i mikroskopsko oštećenje kolona tijekom upalne bolesti crijeva u štakora. Način ekspresije BMP-2 i -7 tijekom upalne bolesti crijeva te nakon liječenja sa BMP-7 ukazuje na značajnu ulogu koštanih morfogenetskih proteina u kontroli oštećenja i cijeljenja tkiva kolona tijekom ove bolesti.ABSTRACT. Aim: Bone morphogenetic proteins -2 and -7, along with their osteoinductive function, play important role in the development and healing of different non-skeletal tissues and organs. The aim of this study was to reveal the expression of BMP-2 and BMP-7 during experimental inflammatory bowel disease, as well as after 14th day of BMP-7 treatment. Methods: Experimental colitis was induced by the intracolonic administration of the clysma containing 2,4,6-trinitrobenzensulphonic acid (TNBS) and ethanol. We investigated the macroscopic and microscopic colon tissue damage during acute and chronic phases of colitis as well as after IV treatment of BMP-7. Results: Imunohistochemical and RT-PCR analyses showed expression of BMP-2 and -7 during acute and chronic phases of inflammatory bowel disease. In the acute phase of colitis, BMP-2 and -7 expressions were located in mucosa of ulcer region. In the chronic phase BMP-7 expression was placed in the colonocytes along the crypt, while BMP-2 expression was located in the coloncytes of surface epithelium and intercrypt table. BMP-7 treatment reduced the expression of BMP-7 and mRNA for BMP-7 but also increased the expression of BMP-2 and mRNA for BMP-2 in colonic tissue. Conclusions: Systemic administration of bone morphogenetic protein 7 decreased macroscopic and microscopic colonic tissue damage during experimental inflammatory bowel disease. The expression pattern of BMP-2 and -7 during inflammatory bowel disease, as well as after BMP-7 treatment suggests an important role of bone morphogenetic proteins in control of colon tissue damage and healing during disease

Aqueous biphasic systems comprising copolymers and cholinium-based salts or ionic liquids: insights on the mechanisms responsible for their creation

Aqueous biphasic systems (ABS) formed by copolymers and ionic liquids (ILs) have demonstrated to be effective separation platforms, but there is still a gap on the complete understanding of the molecular-level mechanisms ruling the two-phase formation for this type of systems. This work addresses the determination of the liquid-liquid equilibrium of ABS composed of cholinium-based salts or cholinium-based ILs and the triblock copolymer Pluronic PE6200 (PL6200). It is demonstrated that PL6200 can form ABS with all investigated cholinium-based salts or ILs, contrarily to most poly(ethylene)glycol polymers, which is due to the presence of hydrophobic propylene oxide (PO) blocks. From the phase diagrams behavior and IL/salt anions properties, it is shown that the formation of ABS with cholinium-based salts is ruled by the anions polar surface and ability to be hydrated, whereas in systems comprising ILs van der Waals interactions between the copolymer and the IL cannot be discarded. The partition of a series of alkaloids in these systems, namely caffeine, nicotine, theophylline, and theobromine, was additionally appraised. It is shown that caffeine, theophylline, and theobromine preferentially migrate to the more hydrophobic PL6200-rich phase, and that their partition depends on the water content in the respective phase, being ruled by the phases’ hydrophobicity. On the other hand, nicotine, with the most prominent hydrophobic character amongst the studied alkaloids, preferentially migrates to the salt- or IL-rich phase, in which interactions occurring between this alkaloid and the IL/salt cannot be discarded. The ABS formed by cholinium dihydrogenphosphate is the most selective system identified to separate nicotine from the remaining alkaloids, giving some insights into their investigation as separation platforms for alkaloids from natural extracts.publishe

Ispitivanje uticaja postupaka dezinfekcije na higijenu u zanatskoj klanici

The objective of this work was to establish, on the grounds of obtained results for the total number of bacteria before and after completed disinfection, whether there are differences in the efficiency of disinfection performed by a professional and disinfection carried out by an unqualified employee in a private slaughterhouse. The material used in these investigations were samples of wet-dry swabs taken over a course of five weeks, before and after disinfection carried out by an unqualified employee and the skilled professional, from the following: the knife used for evisceration, the floor in the evisceration area, from the table serving for bristle removal, and from the floor underneath the bristle removal surface. The wet-dry swabs were taken according to the procedure described in the standard method ISO 18593 (Microbiology of food and animal feeding stuffs - Horizontal methods for sampling techniques from surfaces using contact plates and swabs). Analyzing the taken samples, the total number of bacteria was determined using the standard method ISO 4833 (Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of microorganisms - Colony-count technique at 30°C). Disinfection was carried out using a chlorine preparation (sodium dichloroisocyanurate dihydrate) in a concentration of 0.02% and for an exposure period of 30 min. The results were interpreted on the grounds of the border values in evaluating the hygiene of the equipment, tools, and work surfaces, presented in Commission Decision 471/2001/ EC. The results of the investogations have shown that the disinfection performed by the skilled professional was more efficient than the disinfection performed by the unqualified person, as the total number of bacteria was significantly smaller (p lt 0.01) in the course of all 5 experimental weeks on the evisceration knife, the floor under the bristle removal surface, during weeks 1, 2 and 5, and on the floor in the evisceration area in weeks 1 and 5.Cilj rada je bio da se na osnovu dobijenih rezultata ukupnog broja bakterija pre i posle izvršenih dezinfekcija utvrdi da li su postojale razlike u efikasnosti dezinfekcije koju je izvršilo stučno lice i dezinfekcije koju je sprovelo nestručno lice zanatske klanice. Materijal za ova istraživanja su bili uzorci vlažno-suvih briseva uzetih tokom pet nedelja, pre i posle različitih postupaka dezinfekcije: sa noža kojim se vrši evisceracija, sa podne površine na mestu gde se vrši evisceracija, sa stola za skidanje dlaka i sa poda ispod stola za skidanje dlaka. Postupak uzimanja vlažno-suvog brisa je urađen prema standardnoj metodi ISO 18593 (Microbiology of food and animal feeding stuffs - Horizontal methods for sampling techniques from surfaces using contact plates and swabs). Iz uzetih uzoraka određen je ukupan broj bakterija standardnom metodom ISO 4833 (Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of microorganisms - Colony-count technique at 30°C). Dezinfekcija je obavljena hlornim preparatom (natrijum dihlorizocijanurat dihidrat) u koncentraciji od 0,02%; vreme ekspozicije je 30 min. Rezultati su interpretirani na osnovu graničnih vrednosti kod ocene higijene opreme, alata i radnih površina, predstavljeni u Commission Decision 471/2001/EC. Rezultati ispitivanja su pokazali da je dezinfekcija koju je izvršilo stručno lice bila efikasnija od dezinfekcije koju je izvršilo nestručno lice jer je ukupan broj bakterija bio značajno manji (p lt 0,01), u toku svih V eksperimentalnih nedelja na nožu za evisceraciju, na podnoj površini ispod stola za skidanje dlaka u I, II i V nedelji, i na podu na mestu gde se vrši evisceracija u I i V nedelji