Impregnacija želatin-hitozan filmova etarskim uljem karanfilića pomoću natkritičnog co2 i njihova karakterizacija

Supercritical CO2 impregnation process was used for the first time to fabricate biodegradable gelatin-chitosan (G/Ch) films containing clove oil (CO) for potential use in active food packaging. All the impregnations were carried out at moderately low temperature (40 °C). Aiming to maximize CO loading in the films with acceptable morphological, structural and thermal properties, CO2 pressure, impregnation time and G:Ch mass ratio were varied. Gelatin fraction in the films of 25-50 wt.%, scCO2 pressures of 10-20 MPa and impregnation time of 2-6 h impregnation favoured the CO loading. Processing of the film with equal gelatin to chitosan mass ratio (G/Ch50:50) at 10 MPa for 2 h yielded sufficiently high loading (56 mg CO/gfilm) without an adverse effect on morphological properties. The G/Ch50:50 film was therefore chosen for structural and thermal analyses. ATR-FTIR analysis confirmed successful CO incorporation into the G/Ch50:50 and its interaction with the film. Plasticizing effect of scCO2 and CO on the film was evidenced by DSC. Incorporation of 56 mg CO/gfilm into the G/Ch50:50 didn't affect thermal stability of the film. Beside environmental benefits, supercritical impregnation process enables fast fabrication of G/Ch bio-composite films containing CO, thermally stable to 110 °C, which is suitable for most of food packaging applications. © 2019, CI and CEQ. All rights reserved

Impregnation of cellulose acetate films with carvacrol using supercritical carbon ioxide

Cellulose acetate films were impregnated with carvacrol using supercritical carbon dioxide. The supercritical impregnation process, conducted in a static regime at pressure of 21 MPa and temperature of 50°C, was optimized by variation in the processing time (30 and 120 min) and decompression rate (from 0.3 MPa/min to 36 MPa/min). Characterization of the obtained cellulose acetate films was performed by Atomic Force Microscopy and Differential Scanning Calorimetry. Effects of glycerol and carvacrol on the properties of the films were discussed. Release kinetics from the cellulose acetate film with 31.4% of carvacrol was investigated in a physiological saline solution. In addition, the Higuchi and Korsmeyer-Peppas release models fitted the carvacrol release curve well. Obtained cellulose acetate films impregnated with carvacrol can be of interest for the application in medicine as wound dressings considering their biocompatibility and biodegradability as well as their potential antimicrobial activity or in the food industry as an active food packaging

Analysis of sliding mechanics force degradation during postextraction space closure

Introduction Due to its simplicity, sliding mechanism is very often used in clinical practice for post-extraction space closure, however, the efficiency of this method may be reduced due to friction and changes in the properties of the materials used in this method. The most commonly used methods of sliding mechanics are nickel titanium (NiTi) closed coil spring and elastic chain. The aim of this study was to analyze force degradation in the application of nickel titanium closed coil springs and elastic chains during post-extraction space closure within treatment with fixed orthodontic appliances. Material and Methods The total sample in this study consisted of 78 post-extraction spaces in patients who were indicated for extraction of first premolars and treatment with fixed orthodontic appliances. Nickel titanium closed coil springs and elastic chains were used to close the post-extraction spaces. Post-extraction spaces were monitored for 6 months with follow up examinations every 4 weeks. Measurements of initial force, at the beginning of mechanism activation and residual force in the observation period were performed during control examinations. Results Results of this research showed that with both methods of sliding mechanism there was a significant decrease in the observation period. When using NiTi closed coil springs, the value of average initial force at control examination was between 189.00-210.25 g, while residual was in the range of 117.56-133.50 g that NiTi closed coil springs kept an average 61.57% of initial force. The average initial force on the control examinations for elastic chains was between 184.5-205.38 g, while residual force was in range of 100.39-113.00 g, that elastic chains retained an average 53.41% of initial force. Conclusion There was a significant force degradation between inspections, when sliding mechanics were applied. The loss of force between activation phases of NiTi closed coil springs was smaller compared to the forces produced by elastic chains

Development and validation of new multiresidue method for the determination of multiclass pesticide residue using LCMS/MS in onions

The LC-MS/MS was used in the ESI+ mode. The method was set for the detection of six multiclass pesticides in a single injection. The validation procedure for the method was in accordance with SANTE /11945/2015and it was carried out using blank onion samples spiked with a pesticide mix solution at four levels: 0.01, 0.02, 0.1 and 0.2 μg/mL, with carbofuran– D3 as the internal standard. The linearity of the method was investigated in the range from 0.01 to 0.20 mg/kg. The obtained R2 values for all investigated pesticides (formetanate hydrochloride, spirotetramat, spinosad, dimethomorph, metalaxyl-Mand mandipropamid)were higher than 0.99.The recoveries ranged from96.2 to 101.45 with the precision lower than 8.00%. The LODs were calculated using the Agilent MassHunter B.04.00 software, and the LOQs were experimentally set at 0.01 mg/kg

Primjena polutrajnih i konvencionalnih cemenata s modificiranom tehnikom cementiranja u dentalnoj implantologiji

Objectives: The aim of this study was to evaluate the influence of artificial ageing on the retention force of original semipermanent cements, as well as the possibility of using conventional cements for semipermanent cementation with adequate modification of the cementing protocol. Material and methods: Forty CoCrMo alloy crowns were divided in four groups (each group n=10) and fixed with two semipermanent cements (resin-based and glass ionomer-based cements) and one conventional (zinc phosphate), using conventional and modified cementation techniques on titanium abutments. The samples were stored in humid conditions for 24 hours at 37°C and subjected to thermocycling (500 cycles) and mechanical cyclic loading (7 days, 3, 6, 9 and 12 months function simulation). The cast crowns were removed and the retention force was recorded. Results: The highest initial retention force measured was for zinc-phosphate cement - conventional cementing (198,00±61,90 N), followed in descending order by zinc-phosphate cement - modified cementing technique (152,00±45,42 N), long term temporary cement – GC Fuji Temp LT (57,70±20,40 N), and semipermanent cement - Te-lio CS Cem Implant (56,10±18,68 N). After 12 months, the highest retention force measured was for zinc-phosphate cement - conventional cementing (88, 90±14, 45 N), followed by zinc-phosphate cement – modified cementing (48, 15±14,41N), semipermanent cement GC Fuji Temp LT (16,55±3,88 N) and Telio CS Cem Implant (15,55±5,52 N). Conclusions: Zinc-phosphate cement - modified cementing technique and original semipermanent cements can be recommended for conditional permanent cementing of implant supported crowns. Clinical relevance: The use of semipermanent cements and zinc-phosphate cement - modified cementing technique provides a predictable retrievability of implant-supported crowns.Cilj: Željelo se ispitati kakav je utjecaj umjetnoga starenja na retencijsku silu originalnih (polutrajnih) semipermanentnih cemenata i mogućnost upotrebe konvencionalnih cemenata za polutrajno pričvršćivanje, uz odgovarajuću prilagodbu protokola cementiranja. Materijal i metode: U četiri skupine raspoređeno je 40 krunica izrađenih od Co-Cr-Mo legure (svaka skupina n = 10) i fiksiranih dvama polutrajnim cementima (cementi na bazi smola i staklenoionomera) i jednim konvencionalnim (cink-fosfatni cement), učvršćene konvencionalnom i prilagođenom tehnikom cementiranja na titanijevim nadogradnjama (engl. abutment). Uzorci su bili 24 sata pohranjeni u vlažnim uvjetima na temperaturi od 37 °C nakon čega su podvrgnuti termocikliranju (500 ciklusa) i mehaničkim cikličnim opterećenjima (simulacija 7 dana, 1, 3, 6, 9 i 12 mjeseci u funkciji). Krunice su uklonjene i zabilježena je retencijska sila. Rezultati: Najvišu inicijalnu retencijsku silu pokazao je cink-fosfatni cement – konvencionalno cementiranje (198,00 ± 61,90 N), a slijede ga u silaznom nizu cink-fosfatni cement – prilagođena tehnika cementiranja (152,00 ± 45,42 N), dugotrajni privremeni cement – GC Fuji LT (57,70 ± 20,40 N) i semipermanentni cement Telio CS (56,10 ± 18,68 N). Poslije 12 mjeseci najviša retencijska sila izmjerena je za cink-fosfatni cement – konvencionalno cementiranje (88, 90 ± 14,45 N), a slijede cink-fosfatni cement – prilagođena tehnika cementiranja (48,15 ± 14,41 N) te semipermanentni cementi GC Fuji Temp LT (16,55 ± 3,88 N) i Telio CS Cem Implant (15,55 ± 5,52 N). Zaključak: Cink-fosfatni cement – prilagođena tehnika cementiranja i originalni polutrajni cementi (semipermanentni) mogu se preporučiti za uvjetno trajno cementiranje krunica postavljenih na implantate jer omogućuje optimalnu mogućnost uklanjanja krunica postavljenih na implantate

The Properties Defining Teaching Materials for English Language Courses for IT Students in Serbia

The results presented in this paper are a part of amuch more complex mix-method research on the needs of ITstudents in ELT. The paper reports on the properties definingthe teaching materials suitable for IT students in ELT in tertiaryeducation. Since English language is an essential tool for ITstudents to gain professional knowledge and to grow intocompetent individuals in their field, a rather different approachshould be utilised in order to fully assess and question their needsin ELT. The paper discusses on the properties of teachingmaterials for IT students within the framework of Englishlanguage courses for IT students that has been defined by theresearch. The authors want to define teaching materials suitablefor IT students for mainly two reasons: to help the ones withinsufficient language knowledge to reach the satisfying one and toequip the IT students for the target situations in Englishlanguage that they may find themselves in during studies andupon finding a job. The results presented in this paper can bevaluable for all ESP teachers, especially the ones teaching to thestudents at technical faculties

Security analysis and economic feasibility for virtualization usage in University datacenters

In this paper, authors have analyzed economic andsecurity aspects of server virtualization. The experimentalanalysis includes: the business value of virtualization and impactof virtual environments on computing and security parameters,with applying modern cryptographic systems for data protection.The experiment was designed simultaneously on the traditionalserver and virtual environment. The obtained results show thesignificant advantages of virtual environment in the form ofoptimal allocation and utilization of physical computing resources.Also, the results indicate a significant improvement of parametersin the information security, introducing of the virtual networkadapter which presents virtualized communication channelsconcept between the application server and database server

Impregnacija filmova acetata celuloze karvakrolom pomoću natkritičnog ugljenik(IV)-oksida

Cellulose acetate films were impregnated with carvacrol using supercritical carbon dioxide. The supercritical impregnation process, conducted in a static regime at pressure of 21 MPa and temperature of 50°C, was optimized by variation in the processing time (30 and 120 min) and decompression rate (from 0.3 MPa/min to 36 MPa/min). Characterization of the obtained cellulose acetate films was performed by Atomic Force Microscopy and Differential Scanning Calorimetry. Effects of glycerol and carvacrol on the properties of the films were discussed. Release kinetics from the cellulose acetate film with 31.4% of carvacrol was investigated in a physiological saline solution. In addition, the Higuchi and Korsmeyer-Peppas release models fitted the carvacrol release curve well. Obtained cellulose acetate films impregnated with carvacrol can be of interest for the application in medicine as wound dressings considering their biocompatibility and biodegradability as well as their potential antimicrobial activity or in the food industry as an active food packaging.Filmovi acetata celuloze su impregnirani karvakrolom pomoću natkritičnog ugljenik(IV)-oksida. Proces natkritične impregnacije, izveden u statičkom režimu na pritisku 21 MPa i temperaturi 50°C, je optimizovan varijacijom procesnog vremena (30 i 120 min) i brzine dekompresije (od 0,3 MPa/min do 36 MPa/min). Karakterizacija dobijenih filmova acetata celuloze je izvedena pomoću mikroskopije atomskih sila i diferencijalne skenirajuće kalorimetrije. Efekat glicerola i karvakrola na karakteristike dobijenih filmova je objašnjen. Otpuštanje karvakrola iz filma koji je ima 31,4% primos impregnacije karvakrola je ispitano u fiziološkom rastvoru. Dodatno, Higuči i Korsmejer-Pepas modeli otpuštanja su dobro fitovali krivu otpuštanja karvakrola. Dobijeni filmovi acetata celuloze impregnirani karvakrolom mogu biti značajni za primenu u medicini za previjanje rana uzimajući u obzir njihovu biokompatibilnost i biodegradabilnost kao i potencijalno antimikrobno dejstvo ili u industriji hrane kao aktivno pakovanje

Cellulose Acetate Based Material with Antibacterial Properties Created by Supercritical Solvent Impregnation

Supercritical CO2 was used as a green solvent and impregnation medium for loading cellulose acetate beads with carvacrol in order to obtain a biomaterial with antibacterial properties. Supercritical solvent impregnation was performed in a high-pressure view cell at temperature of 50 degrees C and pressures of 10, 21, and 30 MPa with the processing time ranging from 2 to 18 h. The rate of impregnation increased with the pressure increase. However, maximum impregnation yield (round 60%) was not affected by the pressure applied. Selected samples of the impregnated cellulose acetate containing 6-60% of carvacrol were proven to have considerable antibacterial effect against Gram-positive and Gram-negative bacterial strains including methicillin-resistant Staphylococcus aureus which causes severe infections in humans and animals. In addition, cellulose acetate beads containing 6.0-33.6% of carvacrol were shown to have a porous structure with submicron pores which is of interest for the controlled delivery applications