U radu se provodi analitička analiza jednoosno vlačno opterećene beskonačnehomogene ploče s kružnim otvorom (tzv. Kirschov problem). Eksperimentalnirezultati iz literature daju vrijednosti ...koncentracije naprezanja na rubu otvora, kojesu uvijek manje od teorijske pretpostavke temeljene na klasičnoj teoriji elastičnosti tese za bolje opisivanje razmatranog problema predlaže primjena mikropolarne teorijekontinuuma. U radu je stoga prikazana detaljna analiza temeljena na mikropolarnojteoriji, a dobiveni rezultati tvore bitnu teorijsku podlogu za budući rad.
An analytical analysis of a linear elastic homogeneous and isotropic infinite platewith a circular hole under uniaxial tension (Kirsch’s problem) has been carriedout. Experimental results found in available literature have shown that the stressconcentration factor at the edge of the hole is always lower than the theoreticalprediction based on the classical theory of elasticity. Therefore, the application of themicropolar continuum theory is proposed for a better description of the consideredproblem. The presented results of the detailed analysis provide a suitable theoreticalbasis for the further investigation of the micropolar continuum.
Background. It has been found that higher follicular anti-müllerian hormone (AMH) concentrations predict higher fertilization, implantation and pregnancy rates in women undergoing controlled ovarian ...hyperstimulation (COH). 1, 2 Higher serum luteinizing hormone (LH) concentration may negatively affect oocyte quality.3 The aim of our study was to compare follicular and serum AMH, LH, follicle-stimulating hormone (FSH), estradiol (E2) and progesterone (P) concentrations in modified natural cycles (MNC) and COH cycles. Methods. Women undergoing in vitro fertilization (IVF) were included; 29 in MNC and 30 in COH cycles with gonadotropin and GnRH antagonist. Serum and follicular fluid samples were obtained on the day of oocyte retrieval. Results. Follicular AMH concentration was 2 times higher in MNC than in COH group, while serum AMH concentrations were comparable in both groups. Serum LH concentration was almost 50 times higher and follicular LH concentration almost 8 times higher in MNC than in COH group. Follicular LH concentration was almost 4 times lower in follicles with consequent implantation than in follicles without implantation. Serum and follicular concentrations of AMH and LH correlated with each other in both cycle groups. In COH group, serum AMH concentration was significantly higher with increasing number of retrieved oocytes and significantly lower with women’s advancing age. In MNC group, there was a negative correlation between follicular AMH concentration and volume of follicular aspirate as well as between serum LH concentration and volume of follicular aspirate. Serum FSH concentration was 2 times higher in MNC than in COH group, while follicular FSH concentrations were comparable in both groups. Serum E2 concentration was in MNC 8 times lower and follicular E2 concentration 2 times higher than in COH group. Serum P concentration was 8 times lower in MNC than in COH group, while follicular P concentrations were comparable in both groups. Conclusions. The results of our study indicate that serum and follicular endocrine profile is different in MNC and in COH cycles. Extremely high follicular and serum LH concentration in MNC might affect endometrial receptivity and thus have negative effect on IVF success. Higher serum AMH concentration can predict higher number of retrieved oocytes in COH group.
This work is focused on a quantitative procedure for estimating the generally unfavourable effects that incorrectly drilled holes, characterized by the initial clearance between a rivet and a hole, ...have on the fatigue life of riveted joints. The solution is based on an analytical approach using the stress-severity-factor concept. An experimental programme with riveted-joint specimens characterized by low-load transfer factors was realized in the Czech Aerospace Research Centre (VZLU) test lab under constant amplitude loading. The holes for rivet joints with 4-mm diameters were prepared with the clearance in a range of 0.0–0.16 mm. Force-controlled riveting was applied using a constant pressure force to form the driven head. To prevent fretting events between the joined parts, their anodized contact surfaces were lubricated with MOLYKA, plastic grease with molybdenum disulphide and graphite. The experimental data showed that the load-transfer factor and the fatigue life depend on the initial clearance between a rivet and a hole. The presented procedure introduced the hole-filling factor, integrated in the stress-severity-factor concept as a function of the initial clearance between a rivet and a hole.
A sulphide capacity prediction model of CaO-SiO2-MgO-Al2O3 slags has been developed based on the ion and molecule coexistence theory(IMCT). Sulphide capacity(Cs) of slag for blast furnace (BF) with ...high Al2O3 in the CaO-SiO2-MgO-Al2O3 system at 1773K were measured by applying slag-metal equilibrium method. The feasibility of the developed IMCT model is verified by the sulphide capacity measured in the experiment. Effects of R(w(CaO)/w(SiO2)), w(MgO)/w(Al2O3) and w(Al2O3) on sulphide capacity were discussed. There is a good linear relationship between the experimental value and the predicted value. Therefore, the theoretical model of ion and molecule coexistence can be used to calculate the sulphide capacity of CaO-SiO2-MgO-Al2O3 quaternary slag system. When w(Al2O3)=20% and w(MgO)/w(Al2O3)=0.5, the sulphide capacity of slag increased with the increase of R. When w(Al2O3)=20% and R=1.30, the sulphide capacity of slag increased with the increase of w(MgO)/w(Al2O3). When R=1.30 and w(MgO)/w(Al2O3)=0.4, the sulphide capacity of slag decreased with the increase of w(Al2O3).
U radu su analizirani vremenski nizovi godišnjih prosjeka koncentracije nitrata na pet crpilišta u Varaždinskoj i Međimurskoj županiji. Koncentracija nitrata analizirana je zasebno za gornji i donji ...vodonosni sloj Varaždinskog vodonosnika. Na osnovi vremenskih nizova je utvrđeno da je koncentracija nitrata na svim crpilištima veća u gornjem vodonosnom sloju i da ne prelazi maksimalno dopuštenu koncentraciju (MDK) od 50 mg/L NO3- osim na crpilištu Varaždin gdje je povišena već nekoliko desetljeća.
Pomoću t-testa ispitana je statistička značajnost razlika između godišnjih prosjeka koncentracija nitrata u gornjem i donjem vodonosnom sloju. Analiza je provedena za crpilište Bartolovec u 2003. godinu kada je ta razlika tijekom promatranoga razdoblja bila najmanja. Izračunata t-vrijednost bila je veća od kritične. Stoga je zaključeno da je razlika između godišnjih prosjeka koncentracije nitrata u gornjem i donjem sloju Varaždinskog vodonosnika statistički značajna.
The environmental impact of cadmium use and its accumulation in nature have increased to alarming levels. This study aimed to morphologically and histologically investigate the acute toxic effects of ...cadmium on green toad,
(Pallas, 1769) larvae. Embryos were obtained from specimens collected in amplexus from nature and kept under laboratory conditions until stage 26, when they were exposed to cadmium (0, 1, 5, 10, 25, and 50 Lig L
) for 96 h. The LC
LC
, and LC
values of cadmium were calculated to be 26.98, 35.35, and 46.31 Lig L
, respectively. Our results showed that cadmium had a negative effect on the body size of
larvae (over 1 ng L
). Histological examination detected a fusion of gill lamellae, liver haemorrhage, oedema in the abdominal cavity, and deformations of pronephric tubules (over 10 ng L
). Our findings suggest that the green toad was sensitive to the cadmium treatment, with LC
values lower than those reported by other studies. Thus, this species could be considered a reliable indicator species of environmental stress in aquatic ecosystem.
Ftalati su esteri ftalne kiseline i alifatskih alkohola koji se dodaju u plastične mase da bi se poboljšala njihova mekoća, savitljivost i rastezljivost. Zbog svojih fizičko-kemijskih svojstava ...ftalati su vrlo mobilni i lako migriraju iz plastičnih proizvoda u prostor koji ih okružuje, pa tako dospijevaju u okoliš te su stoga opasni za čovjeka. U radu su ukratko opisana svojstva i raspodjela ftalata u okolišu, toksični učinci na ljudsko zdravlje te zakonska regulativa vezana uz maksimalno dopuštene koncentracije ftalata u vodi za piće i u proizvodima namijenjenima dojenčadi, kao i dopušteni dnevni unos u ljudski organizam. Posebna pažnja posvećena je metodama određivanja ftalata u alkoholnim pićima je razinama ftalata s osvrtom na njihovu pojavnost i koncentracije u šljivovici koja se proizvodi u Hrvatskoj. Obuhvaćena je i tematika vezana za ftalate u denaturiranom alkoholu i neregistriranom alkoholu koji se ilegalno stavlja na tržište. U zaključku su navedene smjernice za učinkoviti nadzor nad putovima izloženosti ljudi ftalatima.
Ftalati su esteri ftalne kiseline i alifatskih alkohola koji se dodaju u plastične mase da bi se poboljšala njihova mekoća, savitljivost i rastezljivost. Zbog svojih fizičko-kemijskih svojstava ...ftalati su vrlo mobilni i lako migriraju iz plastičnih proizvoda u prostor koji ih okružuje, pa tako dospijevaju u okoliš te su stoga opasni za čovjeka.
U radu su ukratko opisana svojstva i raspodjela ftalata u okolišu, toksični učinci na ljudsko zdravlje te zakonska regulativa vezana uz maksimalno dopuštene koncentracije ftalata u vodi za piće i u proizvodima namijenjenima dojenčadi, kao i dopušteni dnevni unos u ljudski organizam. Posebna pažnja posvećena je metodama određivanja ftalata u alkoholnim pićima te razinama ftalata s osvrtom na njihovu pojavnost i koncentracije u šljivovici koja se proizvodi u Hrvatskoj. Obuhvaćena je i tematika vezana za ftalate u denaturiranom alkoholu i neregistriranom alkoholu koji se ilegalno stavlja na tržište.
U zaključku su navedene smjernice za učinkoviti nadzor nad putovima izloženosti ljudi ftalatima.
Phthalates are phthalic acid and aliphatic alcohol esters used as additives to plastic in order to improve its softness, flexibility, and elongation. Phthalates are highly mobile and migrate easily from plastic products into the environment due to their physical and chemical properties.
This study briefly describes the characteristics and distribution of phthalates in the environment, their toxic effects on human health, the legislation regarding the maximum allowed concentration of phthalates in drinking water and products intended for infants, as well as the tolerable daily intake. Special attention is given to the methods of determining phthalates and their levels in alcoholic beverages, with an overview of phthalate occurrences and concentrations in plum brandy made in Croatia. A segment on denatured alcohol and illegally marketed alcohol is also included, as well as guidelines for the effective monitoring of the routes of human exposure to phthalates.
Procesi preoblikovanja bankovnih sustava zemalja u regiji koji su između ostalog uključivali poslove restrukturiranja
i sanacije nesolventnih banaka te privatizacije državnih banaka imali su za cilj ...postavljanje
okvira za poslovanje banke prema suvremenim tržišnim načelima. Otvaranje bankovnog tržišta inozemnom
kapitalu omogućilo je inozemnim bankama pristup na bankovno tržište te se u desetogodišnjem razdoblju
u gotovo svim promatranim zemljama uočava signifikantan porast udjela banaka u inozemnom vlasništvu.
Uočava se također kako su se inozemne banke zbog postojećih ograničenja ulaska na tržište ponajviše služile
strategijom kupnje udjela u već postojećim bankama, a rjeđe strategijom osnivanja potpuno novih banaka.
U usporedbi pokazatelja koncentracije među zemljama, primijećene su razlike koje su ponajprije uvjetovane
različitostima u veličinama bankovnih sustava među zemljama i u veličinama gospodarstava, ali se može uočiti
da su se vrijednosti pokazatelja koncentracije u većim bankovnim sustavima zadržale na nižim razinama
nego u sustavima s manjim brojem banaka.
PDF
