A comparative analysis of milling strategies of complex geometry surfaces

This paper analyses the influence of machining strategies and cutting parameters on the milling of aluminium complex geometry parts. In the first experimental phase, parts were machined with a combination of two roughing strategies and three finishing strategies, with recommended machining parameters. The machining time, machining surface roughness, and the surface geometric accuracy were measured. In the second phase, a new sample was machined with corrected cutting parameters using the best strategy adopted from the first phase. The results have shown that the selection of machining strategy and cutting parameters significantly affects the productivity, quality, and accuracy when machining complex geometry parts

Apical Leakage after Four Endodontic Instrumentation and Filling Procedures

Svrha je bila ispitati apeksnu propusnost punjenih korijenskih kanala uporabom konstrukcije za prijenos tekućine, nakon dvije različite tehnike instrumentacije (“double flare” i step-back”) kombinirane s uporabom dvaju različitih materijala za punjenje (eukaperka i Roeko seal®). U pokusu je rabljen uzorak od 40 trajnih jednokorijenskih zuba. Zubi su dekoronirani na razini caklinskocementnog spojišta, a zatim podijeljeni u četiri skupine od po 10 zuba. Korijenski kanali prve i druge skupine mehanički su obrađeni “double flare” tehnikom, a “stepback” tehnika primijenjena je u trećoj i četvrtoj skupini. kanali su tijekom instrumentacije ispirani 2,5% otopinom NaOCl. Obrađeni korijenski kanali prve i treće skupine punjeni su gutaperka kolčićima i eukaperka pastom tehnikom hladne alteralne kondenzacije, dok je u drugoj i četvrtoj skupini rabljen Roeko seal® umjesto eukaperke tijekom punjenja. Učinjenim endodontskim postupcima stvorene su četiri skupine: skupina DF/EF (double-flare / eukaperka) skupina DF/RS (double-flare / Roeko seal®) skupina, skupina SB/EP (step back/eukaperka) i skupina SB/RS (step back / Roeko seal®). Punjeni korijeni pohranjeni su u sterilnu fiziološku otopinu na 37°C u razdoblju od 7 dana nakon čega su postavljeni u konstrukciju za prijenos tekućine. Propusnost je mjerena pomakom zračnoga mjehurića u kapilarnoj cijevi spojenoj s apeksnim krajem napunjenoga zubnog korijena. Razlika između skupine DF/EF (0,152 μL ± 0,12), skupine DF/RS (0,186 μL ± 0,098), skupine SB/EP (0,195 μL ± 0,12), i skupine SB/RS (0,360 μL ± 0,230) statistički je analizirana Sheffe (ANOVA) testom. statistički znatna razlika utvrđena je između skupine DF/EP i skupine SB/RS. Daljnjom statističkom raščlambom s pomoću Mann-Whitney U testa utvrđeno je da različita tehnika instrumentacije utječe na rezultate raščlambe. U uvjetima pokusa, rezultati dobiveni primjenom konstrukcije za prijenos tekućine pokazuju da različiti materijali za punjenje korijenskih kanala ne utječu na apeksnu propusnost.The aim of this research was to examine apical obturation leakage of filled root canals by a fluid transport model after two different instrumentation techniques (“double flare” and “step-back”) combined with use of two different sealers (eucapercha and Roeko seal®). A sample of 40 permanent single-rooted teeth was used. The coronal part of each tooth was removed at the amelo-cement junction. Teeth were divided into four groups of 10 teeth each. Root-canals of the first and second group were cleaned and shaped by “double flare” technique while “step-back” technique was performed in the third and fourth group. All root-canals were irrigated with 2.5% NaOCl during instrumentation. Prepared root-canals of the first and third group were filled with gutta-percha points and eucapercha sealer by the cold lateral condensation technique while in the second and fourth group Roeko seal® was used as a sealer instead of eucapercha during filling procedure. Filled roots were stored in NaCl 3% at 37°C for 7 days. These procedures formed four groups: group DF/EO (double flare/eucapercha), group DF/RS (double flare/Roeko seal®, group SB/EP (step back/eucapercha) and group SB/RS (step back/Roeko seal®). Each root was mounted in a fluid transport model and leakage was measured by the movement of an air bubble in a capillary glass tube connected to the experimental root section. The difference between group DF/EP (0,152 μL ± 0,12), group DF/RS (0,186 μL ± 0,098), group SB/EP (0,195 μL ± 0,12), and group SB/RS (0,360 μL ± 0,230) was statistically analyzed by Sheffe test. Statiatically significant difference was determined between group DF/EO and group SB/RS. Further statistical anlysis peformed by Mann-Whitney U test showed that different instrumentation technique were responsable for the results of analysis. Under the conditions of this research, results obtained with fluid transport model indicate that there is no statistically significant difference between groups where rootcanals were filled with different materials. Apical leakage was signifuicantly lower where root-canals were instrumented by “double flare” technique

NEW FEED ADDITIVES BASED ON PHYTOGENICS AND ACIDIFIERS IN ANIMAL NUTRITION **

Abstract: Low regulations for feed additives use, has been changed in EU as well as in our country, especially in use of antibiotics as growth promotors. Along years it has investigated an alternative for antibiotics as growth promotors. Essential oilsand organic acids are one of alternative feed, which acting in a few of the most important directions: as antioxidants, metabolic upgraders, growth promotors and development of pathogenic microorganizms controllers, including moulds and bacterias and as environmental protecting through control of amonia and nitrogen excretion. The objective of this paper was to determine the composition of essential oils in a commercial product which, in combination with the blend of organic acids may be used in poultry nutrition as an alternative to antibiotic growth promoters and establish impacts on performance parameters in broilers and microbiological properties of feces. Obtained results showed that the product contained an essential oil in which over 75 % of total mass account for 2-phenol- carvacrol and eugenol

Optimization of co-solvent addition in supercritical fluid extraction of fat with carbon dioxide

This investigation is concerned with supercritical fluid extraction (SFE) using CO2, as an analytical technique for total fat extraction from food and feed samples. Its most significant advantages are safety, cleanness, and shorter extraction time. The main limitation of this technique includes the difficulty of extracting polar lipids due to the non-polar character of the solvent (CO2) used for the extraction. The influence of ethanol as a co-solvent on the SFE of mash pig feed was investigated in this paper. Total fat content was determined by SFE and Soxhlet method for ten commercially available mesh pig feeds. Yields of the fat extracted by both methods were plotted one against the other and compared. Statistically significant difference (p ≤ 0.05) has been found only between the total fat obtained by the Soxhlet extraction and SFE by pure CO2. Based on the mathematical model, maximum yield of the extracted fat is achieved at an ethanol addition of 0.67 ml/g of sample, when the other parameters are the same as recommended by the producer’s procedure

EFFECT OF Artemisia absinthium ESSENTIAL OIL ON ANTIOXIDATIVE SYSTEMS OF BROILER'S LIVER

ABSTRACT: The effect of Artemisia absinthium essential oil (AAEO) on enzymatic activity of superoxide-dismutase (SOD), glutathione-peroxidase (GSHPx), glutathione-reductase (GR), peroxidase (POD), xantine-oxidase (XOD) and non-enzymatic (content of lipid peroxides (LPx) and gluthathione (GSH)) antioxidative status of broilers infected with mixture of oocysts of Eimeria tenella, Eimeria mitis and Eimeria necatrix in comparison to coccidiostat salinomycin was investigated. The in vivo investigation were carried out on 120 Arbor acres broilers of both sexes. Broilers were randomly distributed into four groups. Group A was uninfected and untreated; group B was infected and was kept untreated; group C preventively received coccidiostatic salinomycin in quantity of 60 mg/kg of feed and was inoculated with coccidia species at 21 st day-of-age and group D received in feed AAEO in quantity of 3 g/kg and was infected with Eimeria oocysts at 21 st day-of-age. Livers were collected for the subsequent evaluation of antioxidative status. It was concluded that AAEO added in feed for broilers prevented the development of coccidia oocysts and therefore it can be used as prophylactic feed additive

From Agricultural Waste to Biofuel: Enzymatic Potential of a Bacterial Isolate Streptomyces fulvissimus CKS7 for Bioethanol Production

Purpose To avoid a negative environmental and economic impact of agricultural wastes, and following the principles of circular economy, the reuse of agricultural wastes is necessary. For this purpose, isolation of novel microorganisms with potential biotechnological application is recommended. The current researches in bioethanol production are aimed to reduce the production costs using low-cost substrates and in-house produced enzymes by novel isolated microorganisms. In line with this, in this study valorization of these agricultural by-products by novel isolate S. fulvissimus CKS7 to biotechnological value added products was done. Methods Standard microbiological methods were used for the isolation and characterization of strain. Enzymes activities were determinated using DNS method while, the ethanol concentration was determined based on the density of the alcohol distillate at 20 degrees C. Results The maximal enzymatic activities for amylase, cellulases (carboxymethyl cellulase and Avicelase), pectinase and xylanase were achieved using rye bran as a waste substrate for CKS7 growth. Obtained crude bacterial enzymes were used for enzymatic hydrolysis of lignocellulosic materials including horsetail waste, yellow gentian waste, corn stover, cotton material and corona pre-treated cotton material. The maximum yield of reducing sugars was obtained on horsetail waste and corona pre-treated cotton material. Waste brewer's yeast Saccharomyces cerevisiae was successfully used for the production of bioethanol using horsetail waste hydrolysate and corona pre-treated cotton material hydrolysate. Conclusion The obtained results showed that bacterial strain CKS7 has a significant, still unexplored enzymatic potential that could be used to achieve a cleaner, environmental friendly and economically acceptable biofuel production. [GRAPHICS]