Functional hybrid materials based on aliphatic polyurethanes and inorganic fillers

U ovom radu, sintetisani su hibridni materijali na osnovu alifatičnih poliuretana i čestica silicijum(IV)oksida, mikrometarskih i nanometarskih dimenzija, kao i čestica aluminijum(III)oksida i titan(IV)oksida, nanometarskih dimenzija. Sa ekološkog aspekta, sintetisani hibridni materijali predstavljaju značajne inženjerske materijale jer su proizvodi njihove termičke degradacije znatno manje toksični u poređenju sa produktima degradacije poliuretana za čije dobijanje se koriste aromatični izocijanati. Primenom različitih metoda karakterizacije, sveobuhvatno je ispitan uticaj neorganskih punila na morfologiju, termička, mehanička, dinamičko-mehanička i izolaciona svojstva sintetisanih hibridnih materijala. Uniformna raspodela punila uticala je na poboljšanje toplotnih i mehaničkih svojstava dobijenih materijala. Proučavanjem kinetike termičke razgradnje sintetisanih funkcionalnih hibridnih materijala, dobijeni su podaci o energiji aktivacije termičke razgradnje, prinosu pojedinačnih etapa dekompozicije, kao i o maksimalnim temperaturama kojima hibridni materijali na osnovu alifatičnih poliuretana mogu biti izloženi termičkoj degradaciji u vremenskom intervalu od 60 minuta, a da pri tome ne dođe do gubitka mase veće od 5 mas. %. Nakon detaljnog istraživanja efekta neorganskih punila na toplotna svojstva hibridnih materijala, zabeležen je pozitivan uticaj uniformno dispergovanih neorganskih čestica na temperature relaksacije mekih segmenata, tem-perature topljenja tvrdih segmenata, kao i na temperature kristalizacije sintetisanih materijala. Dobijeni podaci predstavljaju značajne parametre i za proces njihovog recikliranja. Dodatkom malih količina hidrofobnih nanočestica Al2O3 (0,5 i 1,0 mas. %) dobijeni su materijali sa dobrim izolacionim svojstvima, što omogućava njihovu primenu umesto tradicionoalnih izolacionih materijala. Uniformna raspodela manjih količina punila (1,0 i 2,0 mas. % mikrometarskih čestica SiO2; 0,5 mas. % Al2O3; 2,0 mas. % TiO2) uticala je i na poboljšanje mehaničkih svojstava materijala. Ovakva mehanička svojstva zajedno sa odgovarajućim termičkim svojstvima, omogućavaju da se hibridni materijali na osnovu alifatičnih poliuretana i neorganskih punila primene kao mehanički jaki i izdržljivi premazi ili filmovi u biomedicini ili kao ambalažni materijali. Podaci dobijeni ispitivanjem otpornosti na rastvorljivost, opisani su primenom novog predloženog modela, koji obuhvata pojave bubrenja i rastvaranja, sa visokim stepenom koeficijenta determinacije i niskom vrednosti srednje apsolutne greške. Dodatak mikrometarskih čestica SiO2 uticao je na smanjenje brzine i maksimalne vrednosti bubrenja u vodi, acetonu, toluenu i heksanu, kao i na smanjenje brzine bubrenja i smanjenje promene relativne mase nabubrelih uzoraka u acetonu, toluenu i heksanu.polyurethanes and nano and submicron silicium(IV)oxide particles, as well as aluminium(IV)oxide and titanium(IV)oxide nanofillers, were synthesized. From the environmental aspect, obtained hybrids present significant engineering materials, since the products of their thermal degradation are remarkably less toxic in comparison with the products of thermal degradation of polyurethanes based on aromatic isocyanates. Using numerous characterization methods, the impact of inorganic fillers on the morphology, thermal, mechanical, dynamic-mechanical and insulation properties of prepared hybrids was examined in details. Uniform particles distribution in polyurethane matrix affected the significant improvement of thermal and mechanical properties of obtained materials. The detailed information on the influence of silica nanoparticles content on the individual decomposition step contribution and the maximum temperature to which the nanocomposites can be exposed at thermal degradation during 60 min, without the mass loss higher than 5 wt. %, was determined by studying the thermal degradation kinetics of prepared functional hybrid materials. Using thermal analyses (DSM and MDSC), the positive influence of uniform nanoparticles distribution on the temperature of soft segments relaxation, the melting of hard segments as well as crystallization temperature is observed. Obtained results present significant data for the recycling of prepared hybrid materials. The addition of small amount of alumina (0.5 and 1.0 wt. %) caused good insulation properties of polyurethane nanocomposites, enabling them to be used instead of traditional insulation materials. Uniform distribution of low content of submicron silica (1.0 and 2.0 wt. %), alumina (0.5 wt. %) and titania nanoparticles (2.0 wt. %) improved mechanical characteristics of functional hybrid materials, allowing them to be potentially utilized as mechanically strong and durable coatings or films in biomedical applications or as packaging materials. The immersion test data are well described using novel proposed model covering swelling and dissolution phenomena (high coefficient of determination and low values of mean absolute error). The addition of submicron silica affected lowering rate and the amount of swelling in water, acetone, toluene and hexane was, as well as decreasing the rate and mass reduction of swollen sample in acetone, toluene and hexane

Functional hybrid materials based on aliphatic polyurethanes and inorganic fillers

U ovom radu, sintetisani su hibridni materijali na osnovu alifatičnih poliuretana i čestica silicijum(IV)oksida, mikrometarskih i nanometarskih dimenzija, kao i čestica aluminijum(III)oksida i titan(IV)oksida, nanometarskih dimenzija. Sa ekološkog aspekta, sintetisani hibridni materijali predstavljaju značajne inženjerske materijale jer su proizvodi njihove termičke degradacije znatno manje toksični u poređenju sa produktima degradacije poliuretana za čije dobijanje se koriste aromatični izocijanati. Primenom različitih metoda karakterizacije, sveobuhvatno je ispitan uticaj neorganskih punila na morfologiju, termička, mehanička, dinamičko-mehanička i izolaciona svojstva sintetisanih hibridnih materijala. Uniformna raspodela punila uticala je na poboljšanje toplotnih i mehaničkih svojstava dobijenih materijala. Proučavanjem kinetike termičke razgradnje sintetisanih funkcionalnih hibridnih materijala, dobijeni su podaci o energiji aktivacije termičke razgradnje, prinosu pojedinačnih etapa dekompozicije, kao i o maksimalnim temperaturama kojima hibridni materijali na osnovu alifatičnih poliuretana mogu biti izloženi termičkoj degradaciji u vremenskom intervalu od 60 minuta, a da pri tome ne dođe do gubitka mase veće od 5 mas. %. Nakon detaljnog istraživanja efekta neorganskih punila na toplotna svojstva hibridnih materijala, zabeležen je pozitivan uticaj uniformno dispergovanih neorganskih čestica na temperature relaksacije mekih segmenata, tem-perature topljenja tvrdih segmenata, kao i na temperature kristalizacije sintetisanih materijala. Dobijeni podaci predstavljaju značajne parametre i za proces njihovog recikliranja. Dodatkom malih količina hidrofobnih nanočestica Al2O3 (0,5 i 1,0 mas. %) dobijeni su materijali sa dobrim izolacionim svojstvima, što omogućava njihovu primenu umesto tradicionoalnih izolacionih materijala. Uniformna raspodela manjih količina punila (1,0 i 2,0 mas. % mikrometarskih čestica SiO2; 0,5 mas. % Al2O3; 2,0 mas. % TiO2) uticala je i na poboljšanje mehaničkih svojstava materijala. Ovakva mehanička svojstva zajedno sa odgovarajućim termičkim svojstvima, omogućavaju da se hibridni materijali na osnovu alifatičnih poliuretana i neorganskih punila primene kao mehanički jaki i izdržljivi premazi ili filmovi u biomedicini ili kao ambalažni materijali. Podaci dobijeni ispitivanjem otpornosti na rastvorljivost, opisani su primenom novog predloženog modela, koji obuhvata pojave bubrenja i rastvaranja, sa visokim stepenom koeficijenta determinacije i niskom vrednosti srednje apsolutne greške. Dodatak mikrometarskih čestica SiO2 uticao je na smanjenje brzine i maksimalne vrednosti bubrenja u vodi, acetonu, toluenu i heksanu, kao i na smanjenje brzine bubrenja i smanjenje promene relativne mase nabubrelih uzoraka u acetonu, toluenu i heksanu.polyurethanes and nano and submicron silicium(IV)oxide particles, as well as aluminium(IV)oxide and titanium(IV)oxide nanofillers, were synthesized. From the environmental aspect, obtained hybrids present significant engineering materials, since the products of their thermal degradation are remarkably less toxic in comparison with the products of thermal degradation of polyurethanes based on aromatic isocyanates. Using numerous characterization methods, the impact of inorganic fillers on the morphology, thermal, mechanical, dynamic-mechanical and insulation properties of prepared hybrids was examined in details. Uniform particles distribution in polyurethane matrix affected the significant improvement of thermal and mechanical properties of obtained materials. The detailed information on the influence of silica nanoparticles content on the individual decomposition step contribution and the maximum temperature to which the nanocomposites can be exposed at thermal degradation during 60 min, without the mass loss higher than 5 wt. %, was determined by studying the thermal degradation kinetics of prepared functional hybrid materials. Using thermal analyses (DSM and MDSC), the positive influence of uniform nanoparticles distribution on the temperature of soft segments relaxation, the melting of hard segments as well as crystallization temperature is observed. Obtained results present significant data for the recycling of prepared hybrid materials. The addition of small amount of alumina (0.5 and 1.0 wt. %) caused good insulation properties of polyurethane nanocomposites, enabling them to be used instead of traditional insulation materials. Uniform distribution of low content of submicron silica (1.0 and 2.0 wt. %), alumina (0.5 wt. %) and titania nanoparticles (2.0 wt. %) improved mechanical characteristics of functional hybrid materials, allowing them to be potentially utilized as mechanically strong and durable coatings or films in biomedical applications or as packaging materials. The immersion test data are well described using novel proposed model covering swelling and dissolution phenomena (high coefficient of determination and low values of mean absolute error). The addition of submicron silica affected lowering rate and the amount of swelling in water, acetone, toluene and hexane was, as well as decreasing the rate and mass reduction of swollen sample in acetone, toluene and hexane

Ilegalno tržište duhana i duhanskih proizvoda-fenomenološki aspekt i karakteristike kriminalnih aktivnosti

Ilegalno tržište duhana i duhanskih proizvoda-fenomenološki aspekt i karakteristike kriminalnih aktivnost

Precipitation and Characterization of Strontium Phosphates

Spontaneous precipitation of strontium phosphates was studied over a wide concentration range of strontium chloride (2 · 10-4 -- 8 · 10-1 mol dm-3) and of sodium phosphate (4 · 10·4 ·-3 · 10 1 mol dm-3) solutions. In all systems, initial pH was 7.4 and sodum chloride concentration w<•.s 0.15 mol dm-3• The precipitates aged for 1 day and 30 days at 298 K and 310 K were characterized by light microscopy and X-ray powder diffraction. Solid phases SrHP04 (a and P modifications), Sr.10 (P04)s (OHh, Ha Sra (P04);; · · 2H20, and Na [Sr (H20)u] PQ4 were determined .. According to the precipitation boundary after 30 days (equilibrium conditions) the solubility product of Na [Sr (H20)9] P04 is determined as follows: log ([Na+] [Sr2+] [Po4-3]) = -9.98±0.11 (at I = 0.25 mol dm-3, 298 K)

ANALYSIS OF THE RELIABILITY OF AUTOMATED ELECTRIC MOTOR DRIVES OF CABLE CARS AT SKI FIELDS

The basic questions that arise when maintaining an automated electric drive relate to the safety and reliability of the elements in operation. The maintenance strategy of these elements is planned to start from the basic facts related to the plant’s importance, type and purpose. The main purpose of maintenance is the timely detection of a fault and its elimination, i.e. ensuring continuous operation of the plant. In this work, the operation of the cable car was analyzed by monitoring the reliability of the electric drive. An analysis of the significance of reliability coefficients is a potentially new method for maintenance planning. The aim of the research was to define a new strategy for the maintenance of the facility and ensure the maximum safety of skiers through the analysis of previous events. Research is based on coefficients that indicate the reliability, frequency of failures, availability and unavailability of the elements that make up a drive. The essence of the conducted research is based on a new strategy for planning and maintaining such a facility, aiming to ensure skiers’ safety and protection

Characterization of glass ionomer cements stored in various solutions

The aim of this work was to evaluate the nano-mechanical properties of glass ionomer materials, the ion concentrations at the surfaces in relation to the storage media and the pH environments using a scanning electron microscope with an energy-dispersive spectrometer (SEM/EDX). the glass-ionomer-based materials, Fuji Triage (FT), Fuji VIII (FVIII). Fuji IX GP (FIX), were analyzed. The sample comprised 45 cured cement disks. Five specimens of each tested material were placed in 3 storage solutions (saline, acidic solution with pH of 5.5, NaF solution with 0.05 % of fluoride). Nano-indentations were performed with a force up to 30 mN, penetration depths of 2500-2700 nm for 1 d and 21 d after setting. The EDX evaluation was carried out for each experimental disk, identifying the ions: O, Al, Sr, Si, F,Na, P, Ca. The level of significance was placed at p lt 0.05.The highest fluoride proportion at the specimen surface was recorded in the FT material. FT also exhibited the lowest fluoride ions content when stored in low-pH environments compared with the other tested materials (p lt 0.05). The surface hardness of the tested materials decreased from 1.377 GPa (in saline) to 0.03 GPa (in acid). The Young's modulus varied from 14.35 GPa to 0.112 GPa, depending on the material type (Fuji VIII>Fuji IX>FT) (p lt 0.001) and the storage media (p lt 0.001). Both the mechanical and cariostatic surface properties of commercially available glass ionomer materials are affected by the storage media

Primary Teeth Bite Marks Analysis on Various Materials: A Possible Tool in Children Health Risk Analysis and Safety Assessment

Background: All objects put into a child's mouth could be hazardous in terms of trauma and toxic substance exposure. The aims of this study were to evaluate morphological characteristics of the primary teeth bite marks inflicted on various materials and to assess material wear using experimental model. Methods: Bite marks were analyzed on five materials: rubber, plastic, foil, wood, and silicone. In order to mimic children mouthing behavior an experimental setup has been designed using primary teeth placed in dentures and children's equipment specimens. Results: Deciduous teeth make visible and recognizable traces when using physiological forces on all investigated materials. The most significant material loss was revealed in silicone samples, but it has been observed in all material groups, while mouthing with incisors using higher mastication forces were identified as significant predictors for material wear. There were no significant differences between type, species, and morphological-morphometric characteristics of the bite marks which are made by incisors, canines, and molars. Conclusions: In the range of physiological bite forces, deciduous teeth lead to wear of material from which toys are made while the analysis of bite marks in children equipment could give some information regarding the risk of trauma and exposure

Kvantitativna i kvalitativna obilježja motoričkih sposobnosti djece predškolske dobi

The research was conducted with the aim to, using experimental methods, scientifically determine whether an additional physical exercise program in regular working conditions of a preschool institution could result in significant changes in the motor skills of preschool children with an average age of 6.21±0.56 years. A total of 64 preschool children, girls (n=28) and boys (n=36), enrolled in preparatory preschool groups in "Čukarica" preschool in Belgrade. A pre-experimental research plan was used, specifically a single-group design and pretest - posttest. A sample of measuring instruments of motor skills was compiled according to a reduced theoretical model (Gredelj et al., 1975; Kurelić et al., 1975) taken from the research of Bala and Popović (2007). The experimental factor was realized with a total of 48 lessons lasting 35 minutes over a 24-week time interval. The results of the study indicate that the quantitative changes in the final measurement are reflected in the repetitive force of the torso and coordination in favor of better average values of the boys. Two hypothetical motor factors were isolated in initial and final measurements, which can still be interpreted as one general Motor Factor. Qualitative changes in the structure of both extracted factors in the final measurement were not observed. The authors believe that a regular physical education program in preschool institutions is not sufficient for a preparatory preschool group, and that additional kinesiology activities yield better results in the mechanism for structuring the movement and regulating the duration of excitation, especially if it is directed towards the development of biotic motor knowledge. On the other hand, they believe that newer and more meaningful solutions must be found in terms of differentiated physical exercise programs for children, and that only such solutions could lead to qualitative changes in the structure of isolated factors.Istraživanje je provedeno s ciljem znanstvenog utvrđivanja može li dodatan program tjelovježbe u redovitim uvjetima rada predškolske ustanove rezultirati značajnim promjenama u motoričkim sposobnostima djece predškolske dobi s prosječnom dobi od 6,21±0,56 godina. Ukupno je uključeno 64 djece predškolske dobi, djevojčica (n=28) i dječaka (n=36) predškolskih skupina u predškolskoj ustanovi "Čukarica" u Beogradu. Upotrijebljen je predeksperimentalni plan istraživanja, konkretno dizajn jedne skupine, predtest – posttest. Uzorak motoričkih mjernih instrumenata sastavljen je prema reduciranom teorijskom modelu (Kurelića i sur., 1975; Gredelja i sur., 1975) preuzetom iz istraživanja Bale i Popovića (2007). Eksperimentalni faktor bio je realiziran s ukupno 48 termina od po 35 minuta i trajao je u razdoblju od 24 tjedna. Rezultati istraživanja pokazuju da se kvantitativne promjene u finalnom mjerenju odražavaju u repetitivnoj snazi trupa i koordinaciji u korist boljih prosječnih vrijednosti dječaka. Izolirana su dva hipotetska motorička faktora na inicijalnom i finalnom mjerenju, koji se mogu interpretirati još uvijek kao jedan i to Generalni motorički faktor. Nisu opažene kvalitativne promjene u strukturi oba ekstrahirana faktora na finalnom mjerenju. Autori smatraju da redoviti program tjelesnog odgoja u predškolskim ustanovama nije dovoljan za pripremnu predškolsku skupinu, te da dodatne kineziološke aktivnosti daju bolje rezultate u mehanizmu za strukturiranje pokreta i reguliranju trajanja ekscitacije, posebno ako je usmjeren na razvoj biotičkog motoričkog znanja. S druge strane, oni vjeruju da je u smislu diferenciranih programa tjelesnih vježbi za djecu potrebno pronaći novije i značajnije rješenje, a samo takva rješenja mogu dovesti do kvalitativnih promjena u strukturi izoliranih faktora

Cardiac arrest after STEMI and importance of early cardiopulmonary resuscitation in non hospital setting-time is life/myocard

INTRODUCTION: In 23 % of cases, sudden cardiac death can be the first manifestation of coronary artery disease. In these cases pulseless VT and VF are the most common causes for cardiac arrest. Early appropriate resuscitation - involving early defibrillation and appropriate implementation of post-cardiac arrest care lead to improved survival and favorable neurologic outcomes. AIM: Case of successful CPR for out of hospital cardiac arrest (home visit), importance of timely and adequate implementation of CPR by EMS staff. MATERIALS AND METHODS: A descriptive overview of data, dispatcher's Protocol, Physician's Protocol and Patient's Discharge Note. CASE PRESENTATION: At 10:29 pm the emergency crew was dispatched to the scene for 73 y/o woman who was suffering chest and left arm pain. Crew arrived at the patient's residence 4 minutes after the call. The patient's daughter states that her mom had SOB and chest pain that radiated to left arm just 30 minutes prior emergency crew arrival. Ther patient did not have any other cardiac risk factors apart from her age and history of oh da izvini hypertension. During immediate examination the patient's vital signs are stable. (BP 140/80, saturating 95% on room air, pulse 90/min.) Physical exam revealed decreased breath sounds billateraly. The patient was in her bed , dyspneic, awake and alert. During the physical exam, the patient lost her consciousness, and became apneic and pulseless. The patient was immediately moved from the bed to the floor and CPR was started and iv lines were placed. Defibrillator pads (AED) were placed and the recorded rhythm was recognized as ventricular fibrillation (VF). DC shock of 150J was delivered. After defibrillation cardiac monitor registered short asystole and later on short self terminated atrial fibrillation. The patient was lethargic for very short period of time, there were visible spontaneous respirations. Her pulse was palpable and her blood pressure was 135/65. The patient was immediately transferred to clinical center. While being transported to hospital, the patient was given 6 L of oxygen by nasal canula and NS 500 ml. During the patients transport an ECG showed sinus rhythm of 85 bpm with ST segment elevation of 2 mm in III and avF and ST segment depression of 2 mm in I, avL.At the hospital, the patient was transfered to CCU. CONCLUSION: Early CPR and early defibrillation are very important to preserve brain function and function of the other organs. As we can see, immediate CPR followed by early defibrillation dramatically improves survival and favorable neurological outcomes

Uvođenje autohtonih ekotipova češnjaka in vitro pod utjecajem regulatora rasta i svjetlost

Garlic is valuable crop that is used not only for human consumption, but also in pharmaceutical, food and cosmetics industries. Indigenous cultivars have specific beneficial properties that could be permanently lost due to cultivation of new cultivars. Aim of this study was to established two indigenous garlic cultivars in vitro under influence of growth regulator and light. Garlic varieties Slavonian winter (Croatia) and Vincek (Slovenia) were introduced on medium supplemented with two different concentrations of BAP (1 and 1,5 mg/L) and grown under two types of light (FLUO and LED). Results showed there were no significant influence of light type but concentration of growth regulator significantly influenced in vitro development of garlic microshoots of both investigated cultivars. The best treatment for Vincek garlic explants was nutrient medium supplemented with 1.5 mg/L BAP and LED lights, while for Slavonian winter garlic the best treatment showed to be FLUO light and 1,5 mg/L BAP.Češnjak je dragocjena kultura koja se koristi osim za ljudsku prehranu, i u farmaceutskoj, prehrambenoj i kozmetičkoj industriji. Autohtone sorte imaju specifična korisna svojstva koja bi mogla biti trajno izgubljena uzgojem novih kultivara. Cilj ovog istraživanja bio je uspostaviti in vitro protokol za uzgoj dvije autohtone sorte češnjaka pod utjecajem regulatora rasta i svjetla. U in vitro kulturu uvedene su autohtone sorte češnjaka Slavonski ozimi (Hrvatska) i Vincek (Slovenija) na dvije različite varijante hranjive podloge (1 i 1,5 mg/L BAP-a) te su uzgajane pod dvije varijante osvjetljenja (FLUO i LED). Rezultati su pokazali da nije bilo značajnog utjecaja vrste svjetla, ali je koncentracija regulatora rasta značajno utjecala na in vitro razvoj mikroizdanaka češnjaka obje ispitivane sorte. Eksplantati češnjaka Vincek postigli su bolje rezultate na tretmanu hranjive podloge s dodatkom 1,5 mg/L BAP-a i LED svjetla, dok se za Slavonski ozimi češnjak pokazao najbolji tretman FLUO svjetlo i 1,5 mg/L BAP-a