Wood - a carbon depot

V prispevku je predstavljeno globalno gibanje ogljikovega dioksida, ki je zaradi velikih količin najpomembnejši toplogredni plin. Preučevali smo ogljikov cikel in možnosti za njegovo podaljšanje, kjer smo analizirali mehanizme, ki ogljikov dioksid odstranjujejo iz ozračja in ga za daljše časovno obdobje vežejo v trdne substance. Osredotočili smo se na ponor ogljikovega dioksida v lesno biomaso in skladiščenje ogljika v lesu. Na osnovi podatkov za delež komponent lesa in s kemijsko analizo komponent smo izračunali delež ogljika v lesu in ekvivalentno količino ogljikovega dioksida, ki je bila v procesu fotosinteze porabljena za nastanek 1 kg lesne materije. Ugotovili smo, da se za nastanek 1,0 kg absolutno suhega lesa v procesu fotosinteze iz atmosfere povprečno porabi 1,8 kg ogljikovega dioksida.The article examines the global movement of carbon dioxide, the most important greenhouse gas due to its large quantities. We studied the carbon cycle with possibilities of its extension, and analysed the mechanisms that remove carbon dioxide from the atmosphere and bind it into solid substances for a longer period of time. The focus was on carbon dioxide sink into biomass and carbon deposit in wood. On the basis of wood component data and chemical analysis of the components, we calculated the share of carbon in wood and the equivalent quantity of carbon dioxide used in the process of photosynthesis for formation of 1.0 kg of wood matter. It was established that in the process of photosynthesis, approximately 1.8 kg of carbon dioxide is used on average from the atmosphere to form 1 kg of absolutely dry wood

Lesne vrste centralnoafriške republike : vsebnost pepela in silikatov

Izmerjena je bila vsebnost pepela in silicijevega dioksida za 28 tropskih afriških listavcev in ene enokaličnice (Dracaena mannii). Vsebnost pepela je močno variirala. Večina zabeleženih vrednosti se je gibala med 0,3-1,4 %. Najvišja vrednost je bila zabeležena pri Desplatsia floribunda (4,54 %) in najnižja pri Pachyleasma tessmannii (0,07 %). Pri večini vrst je bil SiO2 določen le v sledeh (manj kot 0,01 %). Njegova vsebnost nad 0,1 % je bila izmerjena le pri Gambea beguei (0,128 %) in Manilkara fouilloyana (0,138 %).Data on ash and silica content of 28 Central African hardwoods and one monocotyledon (Dracaena mannii) are presented. Ash content varied considerably. Most of the values were in the range 0.3 - 1.4 %. The highest value was noted for Desplatsia floribunda (4.54 %) and the lowest for Pachyleasma tessmannii (0.07 %). In most species, silica was present only in trace amounts (less than 0.01 %). More than 0.1 % silica was found only in theGambea beguei (0.128 %) and Manilkara fouilloyana (0.138 %)

Tannin based flocculants

Sintetizirali smo flokulante iz različnih vrst tanina. Za sintezo smo uporabili tanin smreke, smreke-jelke, hrasta, mimoze, alepskega bora in kvebrača ter ustrezne kemikalije. Osnova za pridobivanje kationskih flokulantov je bila Mannichova reakcija, ki smo jo izvajali v digestoriju ob stalnem mešanju pri konstantni temperaturi. Testiranje flokulantov je potekalo na standardizirani napravi floktester. Zeta potenciale smo izmerili na zetametru Laser zeetm 501.Various kinds of tannin flocculants were synthesised using spruce tannin, spruce-fir tannin, oak tannin, mimosa tannin, aleppo pine tannin, quebracho tannin, with suitable chemicals. Cationic flocculants were obtained on the basis of the Mannich reaction performed at constant mixing and constant temperature. The testing of flocculants was performed by standardised flock tester. Zeta potentials were measured using Laser Zeetm 501 zeta meter

Spreminjanje pH-vrednosti jesenovine pri konvektivnem sušenju

Changes of pH of sawn wood during conventional drying were studied. Green ashwood boards (Fraxinus excelsior L.), 25.4 mm in thickness, were exposed to 1 month air drying and to kiln drying using 7 schedules, reached by varying temperature (20°C, 30°C and 65°C) and relative air humidity (33% to 90%). Wood samples for pH and moisture content (MC) determination were taken in successive time interval at 3 board`s depths (1/10, 1/3 and 1/2 of thickness).MC was established gravimetrically. pH-value determination of solid wood water system by suspending wood dust into distilled water was used. The lowest used temperature and duration of drying procedure had not significant influence on wood pH. Wood acidification was confirmed at higher drying temperatures (30°C and 65°C), particularly with lower drying rates and prolongation of the procedure. Among all the factors, drying temperature had the greatest impact on the pH-value of wood.Raziskovano je bilo spreminjanje pH-vrednosti lesa med procesom naravnega in komorskega sušenja žaganega lesa. Les velikega jesena (Fraxinus excelsior L.), debeline 25 mm, je bil sušen pod sedmimi konstantnimi sušilnimi režimi, z uporabo 3 temperatur (20°C, 30°C in 65°C) in relativnih zračnih vlažnosti med 33% in 90%. Vzporedno je potekalo zračno sušenje jesenovine v spomladanskih kontinentalnih klimatskih razmerah. Določanje pH vrednosti in lesne vlažnosti je potekalo z odvzemanjem vzorcev v zaporednih časovnih intervalih na 3 globinah žaganic (1/10, 1/3 in 1/2 debeline). Lesna vlažnost je bila določena gravimetrično, pH-vrednost lesa pa z vodno ekstrakcijsko metodo. Vrednosti pH jesenovine se pri sušenju z najnižjo temperaturo niso spremenile. Z višanjem temperature sušenja (30°C in 65°C) se je pH jesenovine značilno zmanjšala, še posebej pri daljšem sušenju in ob uporabi vlažnejših klimatskih razmer v komori. Temperatura sušenja je imela med vsemi dejavniki najbolj izrazit vpliv na pH lesa

Izoliranje in karakteriziranje eteričnih olj iz storžev navadne smreke (Picea abies Karst.), evropskega macesna (Larix decidua Mill.) in rdečega bora (Pinus sylvestris L.)

Preučevana je bila ekstrakcija eteričnih olj iz svežih storžev navadne smreke, rdečega bora in evropskega macesna ter njihova kemijska karakterizacija z metodo plinske kromatografije. Identificirani so različni monoterpeni in določene njihove relativne koncentracije. Ovrednotene so tudi vsebnosti višjih terpenov in podane razlike v kemijski sestavi posameznih eteričnih olj.Extraction and chemical characterization of essential oils from the cones of Norway spruce, European larch and Scots pine are presented in the article. Various monoterpenes have been identified and their relative concentracions calculated by means of gas chromatograpy. The contents of higher terpenes in individual oils have been also evaluated and the differences in their chemical compositions discussed

Lipofilni ekstraktivi srži europskog ariša (Larix decidua Mill.)

The heartwood of two European larch trees was examined for the content of lipophilic extractives. Hexane was used as a solvent for extractions, while gas chromatography with flame ionisation detection and gas chromatography coupled to mass spectrometry were applied for analyses. Different lipophilic groups of compounds, such as fatty acids, resin acids, diterpenoids, sterols, steryl esters and triglycerides were identified and quantitatively evaluated as well as individual low molecular mass components. Distribution of heartwood lipophilics in relation to the trunk heights was also determined and their most likely biological function in wood tissues discussed. The content of hexane extract increased with stem height. Various fatty and resin acids as well as diterpenoid alcohols and sterols were characterized. The predominating lipophilic compounds identified were isopimaric acid and diterpenoid alcohol larixyl acetate. Their average concentrations in examined samples was between 2.0 and 2.5 mg/g. Higher molecular mass lipophilics, e.g. steryl esters and triglycerides, were also present with concentrations between 0.5 and 2.2 mg/g.U radu je prikazan rezultat istraživanja lipofilnih ekstraktivnih tvari u srži dvaju stabala europskog ariša. Kao otapalo za ekstrakciju primijenjen je heksan, a plinska kromatografi ja s plameno-ionizacijskim detektorom i plinska kromatografi ja povezana s masenom spektrometrijom primijenjene su za kemijske analize. Različite lipofilne grupe spojeva, kao masne kiseline, smolne kiseline, diterpenoidi, steroli, sterolni esteri i trigliceridi, identificirane su u uzorcima i kvantitativno su procijenjene. Također su identificirani i procijenjeni pojedini spojevi niskih molekularnih masa. Određena je i raspodjela lipofilnih tvari u srži s obzirom na visinu stabala i objašnjena njihova najvjerojatnija biološka uloga u drvnim tkivima. Sadržaj ekstrakta heksana povećava se s visinom stabla. Različite masne i smolne kiseline, kao i diterpenoidni alkoholi i steroli, također su zastupljeni u srži europskog ariša. Dominantni identificirani lipofilni spojevi jesu isopimarična kiselina i diterpenoidni alkohol. Njihove prosječne koncentracije u ispitivanim uzorcima kreću se između 2,0 i 2,5 mg/g. Lipofilni spojevi veće molekularne mase, npr. sterolni esteri i trigliceridi, također su otkriveni u koncentracijama između 0,5 i 2,2 mg/g

Sustainable Business Communication Management – are Negative Messages to be Avoided or just Communicated Properly?

Implementation of organizational communication, and education on managing communication processes and their correlation to business success are central to sustainable business management. In this regards, negative messages as part of business communication may have poor outcomes and it is widely and wrongly considered that they should be avoided. However, negative messages are an essential element of every business organization, they cannot be avoided and are of high importance for leading sustainable management. This is why an educated and thoughtful approach to communication is required. The main goal of this article is to determine the notion of negative messages, as well as to present the extent of negative messages in the everyday communication of an organization, and emphasize the importance of acquiring skills necessary for a direct and indirect approach to the communication process