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Ricinusovo ulje kao obnovljiva sirovina za dobijanje poliuretanskih materijala
Get PDFTraditionally, polyurethanes (PU) are manufactured by reacting isocyanates with petroleum-based polyols (polyether or polyester). Because oil resources are diminishing and are becoming expensive to produce, engineers and scientist have discovered new technologies to fabricate plastics from renewable resources. The goal of this work was to determine mechanical properties of polyurethanes synthesized from castor oil and different isocyantes: isophorone diisocyanate IPDI, 1,6-diisocyanatohexane (HDI) and aliphatic polycyclotrimer (HDIt). The samples were prepared by a one-step reactive process with stoichiometric balance of reactive groups. The catalysed synthesis was performed at normal pressure. It was estimated that a mechanical properties of prepared samples were strongly influenced by the isocyanate type.Tradicionalno se poliuretani (PU) dobijaju reagovanjem izocijanata sa poliolima (polietarski i poliestarski) koji se uobičajeno dobijaju iz nafte. Pošto se ti resursi smanjuju i postaju sve skuplji inženjeri i naučnici su razvili nove tehnologije za proizvodnju plastike iz obnovljivih sirovina. Cilj ovog rada je bio da se odrede mehanička svojstva poluretanskih materijala dobijenih jednostepenim reaktivnim procesom od ricinusovog ulja i različitih izocijanata: izoforon diizocijanata (IPDI), 1,6-diisocianatoheksana (HDI) i alifatičnog poliizocijanata ciklotrimera (HDIt) sa stehiometrijskim balansom reaktivnih grupa. Katalitička sinteza se odvijala na normalnom pritisku. Ustanovljeno je da su mehanička svojstva dobijenih materijala bila uslovljena tipom izocijanata
Uticaj termina prikraćivanja mladara na karakteristike letorasta kod kruške (Pyrus communis L)
Get PDFU voćarskoj proizvodnji Republike Srpske (BiH) posle jabuke i šljive kruška ima najveći ekonomski značaj. Dominantna upotreba sejanca divlje kruške (Pyrus communis L) kao podloge, uslovljava intenzivan porast i odloženo stupanje u plodonošenje. Intenzivan vegetativan porast u prvim godinama uzgoja utiče na formiranje dugih letorasta sa formiranjem mešovitih pupoljaka na vrhu porasta, koje najčešće prati odumiranje tačaka rasta u njihovom baznom delu. Cilj rada je ispitivanje uticaja termina prikraćivanja mladara tokom vegetacije na karakteristike rasta i razvoja letorasta kod kruške.
Istraživanje je izvršeno u proizvodnom zasadu kruške, starosti 2 godine koji se nalazi u selu Jasenje (45o 09' 32'',16o 44' 43'') opština Kozarska Dubica. Voćnjak je površine 1,2 ha sa ukupno 1350 sadnica. U sortimentu dominira sorta Vilijamovka, sa sortama Abate fetel i Pakhams trijumf kao pratećim. Sve sorte su kalemljene na sejancu divlje kruške (Pyrus communis L). Uzgojni oblik je vitko vreteno i u zasadu se primenjuju standardne pomotehničke i agrotehničke mere. Tretmani novoformiranih mladara na stožini izvršeni su tokom 2015. godine, a analiza formiranih letorasta obavljena je početkom 2016. godine. Mladari su prikraćeni na dužinu od 10 pupoljaka u tri različita termina u periodu intenzivnog porasta, počevši od 25.05.2015. godine; II termin – 15.06.2015. i III termin – 05.07.2015. Razmak između prikraćivanja je u proseku 20 dana. Kontrolni mladari nisu prikraćivani. Svaki tretman je izvršen na po 20 mladara (10 stabala sa po 2 mladara). Kod formiranih letorasta izvršena je analiza rasta (broj novih prirasta i njihova prosečna i ukupna dužina) i razvoja (karakteristike formiraih prirasta, kao i broj formiranih mešovitih pupoljaka).
Sve ispitivane sorte najbolju reakciju u pogledu inciranja novih tačaka rasta i intenziteta obrastanja, pokazale su pri prikraćivanju u prvom terminu. Intenzitet obrastanja predstavlja sortnu karakteristiku i najizraženiji je kod sorte Abate fetel, bez obzira na termin prikraćivanja
Računarski program za procenu troškova poljoprivrednih mašina
No full textA user-friendly computer program is developed in Visual Basic
environment to determine the all types of machinery costs on hour and hectare basis. The
program is also capable to compute breakeven area and time of use of machines to get
back return on investment. The input parameters of the developed program are mainly
initial price, life of machine, rate of interest, fuel cost, labor wages etc. for power source
as well as implement. The total cost is being calculated in two heads namely fixed and
variable cost. The fixed cost consists of depreciation, interest, taxes, housing and
insurance cost, while variable costs includes fuel, lubrication, wages, repair and
maintenance cost. The developed program successfully calculates the cost of operation
in rupees per hour and in rupees per hectare of different combinations of power sources
and implements. The breakeven analysis of any combination of the power source and
implement can also be analyzed. This program can be a useful tool for suggesting the
farmers in purchasing a machine as well as in deciding the custom hiring rates etc. This
can also help to entrepreneurs who are engaged in custom hiring services to decide the
hiring rate of different machinery on the basis of breakeven analysis.Kompjuterski program prilagođen korisniku je razvijen u Visual Basic
okruženju da odredi sve tipove troškova mašina po času i hektaru. Program takođe omogućuje izračunavanje oblasti izjednačenja i vreme upotrebe mašina do povraćaja
investicije. Ulazni parametric razvijenog programa su uglavnom početna cena, radni vek
mašine, kamatna stopa, troškovi goriva, troškovi rada itd, za pogonske mašine i
priključke. Ukupni troškovi se izračunavaju u dve grupe, fiksni i varijabilni troškovi.
Fiksni troškovi se sastoje od depresijacije, kamate, poreza, smeštaja i osiguranja, dok
varijabilni troškovi uključuju gorivo, mazivo, plate, popravke i održavanje. Razvijeni
program uspešno izračunava troškove rada po času rada i po hektaru, za agregate
različitih pogonskih i priključnih mašina. Analiza bilansa svakog agregata takođe može
da se izvede. Ovaj program može da bude korisno sredstvo za preporuke farmerima pri
kupovini mašina, pri određivanju cene iznajmljivanja i sl. Ovo takođe može da pomogne
preduzimačima u servisima da odrede cene iznajmljivanja različitih mašina na osnovu
analize bilansa
Višegorivni pogonski sistem dizel motora
No full textThe design of the fuel system of the tractor diesel with the multistage
heating, allowing to apply pure rapeseed oil as fuel in the diesel engine is described in
the article.U radu je opisana konstrukcija sistema za napajanje gorivom traktorskog
dizel motora sa višestepenim grejanjem, koji omogućuje primenu čistog uja uljane repice
kao goriva za dizel motor
Bujnost, prinos i masa ploda šljive (P. Domestica l.) u zavisnosti od razmaka sadnje
Get PDFThe paper presents the results of a five year (from 2 to 6 vegetation) which compared two growth forms of plum: high density planting and classic growth forms with larger spacing. The research included three plum cultivars: Čačanska lepotica, Čačanska rodna and Stenley. All of them have been grafted on Myrobalan seedlings (P. cerasifera Ehrh.). It has been researched the effect of three variants of the growing system: high density planting, with growing form of spindle bush and forms with bigger spacing such as pyramid and a vase as a growing forms. In the plantation were applied all measures of care except of irrigation. In terms of vigor observed through the trunck cross-sectional area, during all the years of research a bigger vigour was found in trees in traditional growing systems. Generaly, the most vigorous cultivar was Stenley. The yield in the early years after planting (2-5th vegetation) was significantly higher in the cultivars grown in a dense planting. Yield efficiency was also significantly higher in high density planted cultivars. Biennial bearing index was highest at Čačanska rodna. The fruit mass of tested cultivars did not differ depending on spacing.U radu su prikazani petogodišnji rezultati (od 2. do 6. vegetacije) kojima se porede gusta sadnja šljive i klasični sistemi gajenja sa većim razmacima sadnje. Sorte na kojima su vršena istraživanja su Čačanska lepotica, Čačanska rodna i Stanley, kalemljene na sejancu džanarike (P. cerasifera Ehrh.). Ispitivan je uticaj tri varijante sistema gajenja: gusta sadnja sa uzgojnim oblikom vretenasti žbun i retka sadnja sa piramidom i vazom kao uzgojnim oblicima. U zasadu su primenjivane sve mere nege osim navodnjavanja. U pogledu bujnosti posmatrane kroz površinu poprečnog preseka debla, tokom svih godina istraživanja veća bujnost je bila kod klasičnih sistema gajenja, a od sorti najveća kod sorte Stanley. Prinos u početnim godinama po sadnji (2-5. vegetacija) je bio značajno veći kod sorti gajenih u gustoj sadnji. Koeficijent rodnosti je takođe bio značajno veći u varijanti guste sadnje. Indeks alternativne rodnosti je bio najveći kod Čačanske rodne. Masa ploda ispitivanjih sorti se nije razlikovala u zavisnosti od razmaka sadnje
Asocijacija Convolvulo-agropyretum repentis felföldy 1943 u vinogradima rejona sjeverna Bosna
Get PDFThe aim of this paper is to present synmorphological and synecologycal characteristic of the association Convolvulo-Agropyretum repentis Felföldy 1943 in the vineyards region of northern Bosnia. Floristic structures association consists of 66 species. The characteristic species of the association are Convolvulus arvensis L. and Agropyron repens (L.) Beauv. In the biological spectrum association dominate hemicryptophytes (43,94%) and terofit (42,42%), while geophytes underrepresented (9,09%), and they both belong to the characteristic species of the association. The areal spectrum of association dominated by floral elements of high frequency (84,84%). Numerical classification and ordination distinguish the two groups of stands that differ in the floristic composition.Cilj rada je da se prikažu sinmorfološke i sinekološke karakteristike asocijacije Convolvulo-Agropyretum repentis Felföldy 1943 u vinogradima rejona sjeverna Bosna. Florističku stukturu asocijacije čini 66 vrsta. Karakteristične vrste asocijacije su Convolvulus arvensis L. i Agropyron repens (L.) Beauv. U biološkom spektru asocijacije dominiraju hemikriptofite (43,94%) i terofite (42,42%), dok su geofite manje zastupljene (9,09%), a pripadaju im obe karakteristične vrste asocijacije. U areal spektaru asocijacije dominiraju florni elementi širokog rasprostranjenja (84,84%). Numeričkom klasifikacijom i ordinacijom mogu se izdvojiti dvije grupe sastojina koje se razlikuju po florističkom sastavu
Komparativna analiza sadržaja Pb, Fe i Cu u plodovima šipka u zavisnosti od lokaliteta
Get PDFThe area of Herzegovina is known for its intensive cultivation of pomegranate, which is placed on the market either as a fruit or as a processed product. Main task of this research is to determine to which degree agricultural land is contaminated with heavy metals and organic pollutants on the wider area of Mostar and to record the amount of heavy metals that is accumulated in a ripe fruit.
Determining of the level of lead, iron and copper in the ripe fruit of pomegranate, the clean grain, and the grain with mesocarp. The research is carried out at three different localities, depending from the place of cultivation from highway M17 and local roads. The same heavy metals were determined in the soil at two different depths.Područje Hercegovine poznato je po intenzivnoj proizvodnji šipka, koji se u sirovom ili prerađenom stanju plasira na tržište. Osnovni zadatak ovog istraživanja je utvrditi stepen kontaminiranosti poljoprivrednog zemljišta teškim metalima i organskim zagađivačima na širem području grada Mostara, te evidentirati količinu teških metala koja se akumulira u zrelim plodovima.
Određivanje sadržaja olova, željeza i bakra u zrelim polodovima šipka, čisto zrno i zrno sa mezokarpom. Istraživanje je izvedeno na tri različita lokaliteta, zavisno od udaljenosti mesta uzgoja od magistralnog puta M-17 i lokalnih puteva. Isti teški metali su određivani i u zemljištu na dvema različitim dubinama
Monitoring alergenog polena u Čačku tokom 2015.godine
Get PDFThis paper presents a report of allergenic pollen monitoring obtained by an analysis of measurements including the types and numbers of pollen grains in air sampled, and pollination period for each allergenic plant in the Town of Čačak. The degree of allergenicity was highest for ambrosia, followed by birch and grass pollen. Pollination period was longest in grasses (about 160 days), followed by nettles (somewhat over 140 days) and plantains (about 130 days), as opposed to less than 100 days in all other species and families. In Čačak, during 2015, a total of 1728 pollen grains of ambrosia were measured, with a maxium daily concentration of 375 grains per m3 air on 2 September 2015. During pollen emission from trees, birch had 2309 pollen grains during its pollination, with 531 grains per m3 of air on 16 April 2015, which was an approximately 9-fold increase relative to limit values.Rad je prikaz monitoringa alergogenog polena dobijen analizom rezultata merenja gde su određene vrste i broj polenovih zrna u vazduhu kao i dužina polinacije za svaku alergenu biljku na teritoriji grada Čačka. Najveći stepen alergenosti pokazuje ambrozija, zatim breza i trave. Po dužini polinacije izdvajaju se trave (oko 160 dana), zatim slede koprive (nešto iznad 140 dana), bokvice (oko 130 dana), dok su sve ostale vrste i porodice polinirajuće manje od 100 dana. U Čačku je u toku 2015. godine izmereno ukupno 1728 polenovih zrna ambrozije sa maksimalnom dnevnom koncentracijom od 375 zrna po m³ vazduha 02.09.2015.godine. Tokom emitovanja polena drveća breza je imala ukupno 2309 polenovih zrna u toku svoje polinacije sa 531 zrna po m³ vazduha 16.04.2015. što je oko 9 puta više od granične vrednosti
Bioactive Constituents from Lichens
Get PDFHere we investigate antioxidant and antimicrobial activities of the acetone extract of the Cladonia rangiferina and their fumarprotocetraric acid. Antioxidant activity was evaluated by free radical scavenging, superoxide anion radical scavenging, reducing power and determination of total phenolics. As a result, fumarprotocetraric acid had larger free radical scavenging activity with (IC50 = 228.46 μg/mL). Tested samples also had effective reducing power and superoxide anion radical scavenging. Total phenolic content was determined as pyrocatechol equivalent. The antimicrobial activity was estimated by determination of the MIC, where most active was fumarprotocetraric acid with MIC values ranging from 0.03 to 0.25 μg/mL
Bioactivity of Edible Mushrooms
Get PDFHere we evaluated antioxidant and antimicrobial activity of the acetone and methanol extracts of the mushrooms Amanita rubescens and Russula cyanoxantha. Antioxidant activity was evaluated by free radical scavenging, reducing power activity and determination of phenolic content. As a result of the study acetone extracts from Russula cyanoxantha was more powerful antioxidant activities (IC50 = 86.279 µg/ml). Moreover, the tested extracts had effective reducing power. Total content of phenol in extracts was determined spectrophotometrically. The antimicrobial activity was estimated by determination of the minimal inhibitory concentration by using microdilution plate method. Generally, the tested mushroom extracts had relatively strong antimicrobial activity against the tested microorganisms