A new refractory alloy, HfMoNbTiCr, was obtained by replacing Zr with Cr or Mo in the HfMoNbTiZr or HfNbTiCrZr alloys using vacuum arc melting. The phase components, microstructures and compressive ...properties of the alloy in the as-cast and annealed states were investigated. The results showed that the phase components changed from a single BCC phase in HfMoNbTiZr and BCC+Laves phases in HfNbTiCrZr to multiple phases – primarily two BCC phases and two cubic Laves phases – in HfMoNbTiCr. Notably, the yield and ultimate compressive strength of the as-cast alloy significantly increased from 1719 and 1803 MPa to 1851 and 2489 MPa, without a decrease in the ductility. The stress fields induced by Mo and the Cr-containing Laves phases were responsible for the enhanced strength, while the stiff network-like framework composed of intrinsically-strong Cr-containing Laves phases may have played a vital role in retaining the ductility.
The influence of chemical composition and heat treatment on the mechanical properties and formability of the selected commercial aluminium alloy EN AW 5454 was investigated. The main properties of ...alloy 5454 from the AA 5xxx series are very good corrosion resistant and has good formability. From the cast slab a 50 mm thick slice was taken in the width cross section in the slab centre. One half of the slice was homogenised for 10 hours at a temperature of 530 °C. The cast and homogenised samples were investigated using light and scanning electron microscopy. For the study of the influence of the heat treatment, samples in the as-cast state were annealed in the laboratory furnace at a temperature of 530 °C for 4, 6, 8, 10 and 12 hours. To study the influence of chemical composition, four different samples were prepared: the first without additions, the second with an addition of 1 wt% Mn, the third with 3 wt% Mg and the fourth with an addition of both elements, Mn and Mg. The XRF analyses confirmed the desired chemical composition of all four produced alloys. Half of each alloy’s sample was homogenised at the same temperature and time as the base alloy in the as-cast state. The hot deformation behaviour of the different alloys was investigated using cylindrical hot compression tests performed on a Gleeble 1500D thermo-mechanical simulator. By comparing flow curves a high influence of the thermo-mechanical parameters on the alloy formability can be seen. The alloy has good workability and with the addition of Mn and Mg, the stress values are higher than those of the base alloy.
Recently, anthropogenic fires in protected areas have become more frequent. I studied the response of the spider community after an extensive summer fire in the ‘Striltsivskyi Steppe’ Reserve in ...eastern Ukraine. A total of 117 spider species was found in the pre-fire period, 40 species were registered in the first and 89 species in the third post-fire year. Herb-dwelling spiders began to colonize burnt plots in July, when juveniles of the new generation began dispersing. In September, their abundance was similar to that of undisturbed steppe and within three years, the spider assemblages recovered almost completely. Cursorial ground-dwellers in the first post-fire year decreased in species richness and increased in activity density. In the third year, their species diversity and activity density became much higher than in control plots. Some xerophilous species benefited from the fire. Litter dwellers are extremely vulnerable. During the three post-fire years, their numbers and diversity did not recover. Some rare species with a patchy geographical distribution disappeared from the local fauna. Such a reaction of endangered species is the main restriction on the use of fire as a conservation management. The prerequisite for its implementation is maintaining relevant refuges for threatened species.
Antropogeni požari na zavarovanih območjih so v zadnjem času vse bolj pogosti. Proučevala sem odziv združbe pajkov po ekstenzivnem poletnem požaru v rezervatu ‘Striltsivskyi Steppe’ v vzhodni Ukrajini. V obdobju pred požarom sem našla 117 vrst pajkov, 40 vrst je bilo zabeleženih v prvem letu, 89 vrst pa v tretjem letu po požaru. Pajki, ki prebivajo na zeliščih, so začeli naseljevati požgane ploskve julija, ko so se začeli razširjati juvenilni osebki nove generacije. Septembra je bila njihova abundanca podobna kot v nemoteni stepi in po treh letih se je vrstna sestava pajkov popolnoma obnovila. Vrstna pestrost pajkov, ki prebivajo na tleh, se je v prvem letu po požaru zmanjšala, povečala pa se je njihova aktivna gostota. V tretjem letu sta bili vrstna pestrost in aktivna gostota višji kot na kontrolnih ploskvah. Nekatere kserofilne vrste so imele zaradi požara prednost. Vrste, ki jih najdemo v opadu, so izredno ranljive. Njihovo število in pestrost se v treh letih po požaru nista obnovila. Nekatere redke vrste z zaplatasto geografsko razširjenostjo, so izginile s tega območja. Odziv redkih vrst je glavna omejitev za uporabo ognja za naravovarstven način gospodarjenja. Predpogoj za njegovo uporabo je vzpostavitev ustreznih zatočišč (refugijev) za ogrožene vrste.
Ograjena naselja veljajo za škodljivo obliko urbane segregacije, saj so to varovane stanovanjske soseske z ekskluzivno infrastrukturo. Cilj indonezijske vladne politike, povezane z zagotavljanjem ...cenovno uravnotežene stanovanjske oskrbe, je ustvariti stanovanjske komplekse ali naselja z ekonomsko mešano sestavo prebivalstva, ki spodbujajo interakcijo med družbenimi sloji in zmanjšujejo cedalje vecje socialne razlike. Namen clanka je potrditi pojav družbene interakcije med socialno-ekonomskimi sloji v naseljih z ekonomsko mešano sestavo prebivalstva. Za boljše razumevanje družbene interakcije med stanovalci so avtorji najprej proucili razloge za izbor tovrstne stanovanjske soseske, in sicer za vsak socialno-ekonomski sloj posebej. Za to so uporabili metodo vrednotenja po vselitvi na primeru ograjenega naselja v Cibuburju v Zahodni Javi, ki je znan po dobri kakovosti stanovanjskih sosesk in infrastrukture. Izsledki raziskave kažejo, da je varovanje še vedno glavni razlog za to, zakaj se ljudje odlocijo živeti v tovrstnem ograjenem naselju. Zaradi manjše ekskluzivnosti naselja pa je cedalje manjša tudi pogostost uporabe tamkajšnje infrastrukture in površin, pripadniki posameznih družbenih slojev pa se raje kot s stanovalci istega stanovanjskega kompleksa v naselju družijo s pripadniki istega sloja v drugih stanovanjskih kompleksih, kar se ne ujema s cilji politike cenovno uravnotežene stanovanjske oskrbe.
V prispevku je predstavljena starostna in spolna sestava Slovencev v Vojvodini. Posebna pozornost je namenjena obdobju po 2. svetovni vojni in analizi sprememb starostne sestave. Različni pokazatelji ...te sestave (srednja starost, indeks staranja, idr.) so bili analizirani s pomočjo statističnih in matematičnih postopkov. Rezultati prinašajo nova spoznanja o demografsko sliko Vojvodine z vidika Slovencev in opozarjajo na njihovo neugodno starostno sestavo. So namreč ena od starejših etničnih skupin, ki jim od nadaljevanju ugotovljenih trendov grozi izumrtje.
The objective of the present study was to determine the effect of linseed oil supplementation on performance, fatty acid composition and oxidative status of rabbits. Twelve male SIKA rabbits were ...divided into two groups. The control group (n = 4) received commercial diet and the linseed group (n = 8) received commercial diet containing 9% of linseed oil, which was sprayed onto the pellet. R abbits were slaughtered at 115 days of age, 52 days after the start of the experiment. Live weight, weight gain, feed intake and feed efficiency were recorded. The fatty acid composition of muscle, adipose tissue and liver was determined by the in situ transesterification method and gas chromatography-flame ionisation detection (GC-FID). In order to evaluate the oxidative status of rabbits, the malondialdehyde (MDA) concentration in plasma, liver and muscle were measured. The results show that it is possible to enhance proportion of n-3 polyunsaturated fatty acids (PUFA) in rabbit's muscle, adipose tissue and liver by adding linseed oil in the diet without detrimental effect on productive performance. Linseed oil addition improved fatty acid composition in all tissues by increased PUF A proportion and decreased proportion of saturated and monounsaturated fatty acid. Linseed oil also reduced n-6/n-3 PUF A ratio in all tissues. However, linseed oil addition led to significantly higher MD A concentrations in plasma, liver and muscle. Since PUF A are highly susceptible to oxidation, further research is needed to focus on protecting animal and their products from lipid oxidation by adding various natural antioxidants to the diet.
V poskusu smo preučevali vpliv dodatka lanenega olja v krmo na proizvodne lastnosti, maščobnokislinsko sestavo in oksidacijski status kuncev. D vanajst kuncev slovenske mesne linije SIKA smo razdelili v dve skupini. Kontrolna skupina (n = 4) je uživala standardno krmo, poskusna skupina (n = 8) pa standardno krmo z dodatkom 9 % lanenega olja, ki smo ga nanesli na pelete. Kunce smo zaklali pri starosti 115 dni, 52 dni po začetku poskusa. V času poskusa smo zapisovali maso živali, prirast, zauživanje in izkoristek krme. M aščobnokislinsko sestavo mišic, maščobnega tkiva in jeter smo določili z in situ transesterifikacijo in kapilarno plinsko kromatografijo. Za določitev oksidacijskega statusa kuncev smo izmerili koncentracijo malondialdehida (MDA) v plazmi, jetrih in mišici. R ezultati so pokazali, da lahko z dodatkom lanenega olja v krmo kuncev povečamo delež n-3 večkrat nenasičenih maščobnih kislin (VNMK) v mišici, maščobnem tkivu in jetrih brez negativnih učinkov na proizvodne lastnosti. D odatek lanenega olja je izboljšal maščobnokislinsko sestavo s povečanjem deleža VNMK in zmanjšanjem deleža nasičenih in enkrat nenasičenih maščobnih kislin, kar je znižalo tudi razmerje n-6/n-3 VNM K v vseh tkivih. D odatek lanenega olja je značilno povečal koncentracijo MD A v plazmi, jetrih in mišici. Ker so VNM K zelo podvržene oksidaciji, so potrebne nadaljnje raziskave, v katerih se bo potrebno osredotočiti na zaščito živali in njihovih produktov pred lipidno oksidacijo z dodajanjem različnih naravnih antioksidantov v krmo.
Namen prispevka je prikazati možnost kombiniranja različnih matematičnih metod za analiziranje sestave krmnih obrokov v danih okoliščinah. Z matematičnimi modeli, ki temeljijo na omejeni ...optimizaciji, smo proučevali cenovno-stroškovna razmerja v obdobju 1998 do 2008 in iskali morebitne spremembe v sestavi racionalnih krmnih obrokov za goveje pitance. Za analizo smo uporabili normativne in pozitivne matematične metode. S pomočjo klasičnega linearnega programa, nadgrajenega s tehtanim ciljnim programom, smo izvedli normativno analizo. Da bi ugotovili, kako bi se v danih razmerah odločal povprečen rejec, pa smo simulacijo izvedli tudi s pozitivnim matematičnim programiranjem. Dobljeni rezultati kažejo, da se je sestava racionalnega krmnega obroka v zadnjih desetih letih nagnila v prid koruzne silaže, izrazito pa se je zmanjšala količina travne silaže v obroku. Zaradi naravnih danosti v Sloveniji take spremembe niso izvedljive, zato bomo morali več pozornosti posvetiti zniževanju stroškov pridelave travne silaže.
The aim of this study was to characterize the chemical profile of dry-cured ham selected and processed in accordance with the Slovenian consortium rules for »Kraški pršut« and to investigate the ...differences between the Biceps femoris (BF) and the Semimembranosus (SM) muscle. The free amino acid content, moisture, salt, protein, total nitrogen, non-protein nitrogen, proteolysis index, intramuscular fat and dry matter were analysed in 135 samples of dry-cured hams including both muscles. A modified method for sample preparation was developed for determination of free amino acids in dry-cured ham. The method was validated for linearity, limit of detection, limit of quantification, precision and uncertainty. According to the validation parameters the method is appropriate for the determination of free amino acid content in dry-cured ham. Higher content for several free amino acids and total free amino acids were determined in the BF muscle compared to the SM muscle.
Floristična sestava travinja opredeljuje pridelovalno in naravno vrednost travne ruše. Ker ugodna botanična sestava ruše za pridelovanje krme pogosto pomeni njeno vrstno siromašnost, smo ta odnos ...želeli preučiti za travnike Ljubljanskega barja. Leta 1999 smo zasnovali na zvezah Arrhenatherion (poskus T1) in Molinion (poskus T2) dva travniška poskusa v obliki deljenk s štirimi ponovitvami. Glavne parcele predstavljajo pogostnost rabe (2 košnji na leto z zapoznelo in običajno 1. košnjo, 3 košnje in 4 košnje), podparcele pa stopnjo gnojenja (negnojeno – kontrola, PK in NPK z različni odmerki N). Rezultati raziskave, ugotovljeni pred 1. košnjo v 4. letu trajanja poskusov: V primerjavi s kontrolo ni gnojenje tako s PK kot NPK gnojili na nobenem poskusu zmanjšalo rastlinske pestrosti v ruši. Povprečno je bilo v negnojeni in gnojeni ruši po 20 vrst. Število vrst v ruši se ni zmanjšalo niti pri povečanem številu košenj (19 vrst pri 2 košnjah nasproti 20 vrstam pri 3 oz. 4 košnjah). Zastopanost metuljnic se je na obeh poskusih opazno povečala pri PK gnojenju in ekstenzivni rabi – 2 ali 3 košnjah. Večja pogostnost rabe je pri vseh postopkih delovala pozitivno na delež trav v ruši. Na poskusu T1 je gnojenje zmanjšalo relativno zastopanost močvirske preslice v travni ruši. Njen delež se je še dodatno zmanjšal s povečanjem košenj iz dve na tri oz. štiri. Zastopanost močvirske preslice je bila največja v negnojeni 2 kosni ruši in najmanjša v NPK gnojeni 4 kosni ruši.
Genetic and environmental parameters for 38 983 test-day records of daily milk yield (DMY), fat (FC) and protein (PC) content, collected between 1994 and 2002, were estimated on 3,068 dairy ewes of ...the three Slovenian breeds. A multivariate restricted maximum likelihood method was used for estimation, where every test-day record was treated as a different trait. Fixed part of the multitrait animal model for DMY, FC, and PC included breed and lambing season as classes, while stage of lactation, parity, and litter size were covariates. Random part of the model contained additive genetic effect and the effects of flock test month and permanent environment over lactations. Heritability estimates for individual test-days were between 0.10 and 0.23 for DMY, 0.09 and 0.18 for FC, and 0.19 and 0.28 for PC. The flock test month effect explained most of the phenotypic variance: 0.18 to 0.41 for DMY, 0.26 to 0.45 for FC, and 0.24 to 0.44 for PC. A lower variance ratio was explained by the permanent environment effect over lactations: 0.09 to 0.15 for DMY, 0.02 to 0.11 for FC, and 0.02 to 0.09 for PC. Additive genetic correlations between individual test-days were high in all three milk traits for adjacent months of lactation. They decreased when the interval between months of lactation increased. The structure of additive genetic correlations showed that the observed milk traits in the different stages of lactation were genetically not the same trait, since the correlations between distant months of lactation were lower than one.
Ocenjevali smo genetske in okoljske parametre za 38 983 meritev na kontrolni dan za količino mleka (DKM) ter vsebnost maščobe (VM) in beljakovin (VB) v mleku pri 3068 mlečnih ovcah treh slovenskih pasem. Meritve so bile zbrane med leti 1994 in 2002. Za oceno parametrov smo uporabili večlastnostno metodo omejenega največjega verjetja, kjer je vsaka meritev na kontrolni dan obravnavana kot druga lastnost. Sistematski del večlastnostnega modela živali za DKM, VM in VB je vključeval pasmo in sezono jagnjitve kot razrede, stadij laktacije, zaporedna jagnjitev in velikost gnezda pa so bili vključeni kot kovariable. Naključni del modela je vseboval aditivni genetski vpliv živali, vpliv skupnega okolja v tropu in vpliv permanentnega okolja živali. Heritabilitete za posamezne mesece laktacije so bile med 0,10 in 0,23 za DKM, med 0,09 in 0,18 za VM in med 0,19 in 0,28 za VB. Skupno okolje v tropu je pojasnilo največji del fenotipske variance: 0,18 do 0,41 za DKM, 0,26 do 0,45 za VB in 0,24 do 0,44 za VB. Vpliv permanentnega okolja živali je pojasnil manjši delež variance: 0,09 do 0,15 za DKM, 0,02 do 0,11 za VM in 0,02 do 0,09 za VB. Aditivne genetske korelacije med posameznimi lastnostmi mlečnosti sosednjih mesecev laktacije so bile močne in so se z oddaljevanjem mesecev laktacije zmanjševale. Struktura aditivnih genetskih korelacij kaže, da lastnosti mlečnosti v različnih stadijih laktacije genetsko niso ista lastnost, saj so korelacije med oddaljenimi zapisi manjše od ena.
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