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Physical properties play an important role in predicting wood quality. The aim of this study was to investigate radial variations in physical properties of sycamore maple (Acer pseudoplatanus L.) wood, to determine the border between juvenile and mature wood and to compare them with analogous variations in beech wood. Radial variation of density in absolutely dry condition, maximum density, nominal density, longitudinal, radial, tangential and volumetric shrinkage, maximum moisture content and annual ring width on five sycamore maple trees from Medvednica region in Croatia were determined. Observing the trend curves and comparing average values of physical properties, different zones in the cross section of the trunk were determined. In the first zone, from the pith to about 30th annual ring, more rapid changes in physical properties occurred. It is followed by transitional zone, which ranges roughly from 30th to 40th annual ring. After 40th annual ring, less pronounced changes in measured physical properties occurred. Sharp boundary between juvenile and mature wood zones could not be determined. According to the results, the first zone is considered to be juvenile wood, while mature wood starts after the 30th annual ring., Fizička svojstva drva imaju važnu ulogu u predviđanju njegove kvalitete. Cilj ovog rada bio je istražiti radijalne varijacije fizičkih svojstava drva gorskog javora (Acer pseudoplatanus L.), utvrditi granicu između juvenilnoga i zrelog drva te ih usporediti s odgovarajućim varijacijama u drvu bukve. Utvrđene su radijalne varijacije gustoće u apsolutno suhom stanju, gustoća pri maksimalnom sadržaju vode, nominalna gustoća, longitudinalno, radijalno, tangentno i volumno utezanje, maksimalni sadržaj vode i širina godova u drvu pet stabala gorskog javora s Medvednice u Hrvatskoj. Iz dobivenih krivulja i usporedbe prosječnih vrijednosti fizičkih svojstava drva utvrđene su različite zone na poprečnom presjeku debla. U prvoj zoni, od srčike do približno 30. goda, vidljive su znatnije promjene fizičkih svojstava drva. Slijedi prijelazna zona, koja se otprilike proteže od 30. do 40. goda. Nakon 40. goda promjene fizičkih svojstava drva manje su vidljive. Oštru granicu između zona juvenilnoga i zrelog drva nije moguće odrediti. Na temelju dobivenih rezultata pretpostavljeno je da je prva zona juvenilno drvo, a nakon 30. goda počinje zrelo drvo.

This paper analyzes the effect of adding wood attacked by brown rot fungi to basic wood raw material with the aim of increasing the mechanical strength of wood pellets. Wood attacked by brown rot fungi has an increased share of lignin which is natural glue and can contribute to better mechanical properties of wood pellets. Wood pellets were produced on a single pellet press and pressed with adjusted production parameters at two different temperatures. Produced pellets were tested on some mechanical and physical properties. The analysis of experimental results has shown the statistical significant improvement of the mechanical properties of pellets by adding brown rot fungi wood.

The article presents preliminary results of the biological durability of oil heat treated (OHT) alder wood (Alnus glutinosa) against pure cultures of rot fungi (Postia placenta and Trametes versicolor) in lab condi- tions. The modifi cation was performed by heating of specimens immersed in soya oil. There were four heating regimes of different duration (6 and 10 hours) at fi nal temperature of 180 and 200 oC. The increase in mass (MI) caused by modifi cation and mass loss of wood caused by fungal decay (ML) were determined. In addition, the natural durability of alder wood was determined and compared to the natural durability of beech wood as the reference wood species. After modifi cation of alder wood at 200 °C, MI was lower than after treatment at 180 °C. MI was also lower after 10 hours of treatment than after 6 hours of treatment. The results showed signifi cantly increased biological dura- bility of modifi ed alder wood against both tested fungi. The effect of OHT on increasing the biological durability of alder wood was higher against the fungus P. placenta. It seems that the fungus T. versicolor favours the remained oil after modifi cation causing higher mass loss. The results showed that alder wood, thermally modifi ed in soya oil by testing regimens, is not suitable for applications in use classes 3-5.

The wooden pavilion Jeka (Echo) was built in 1843 according to the plans of the Austrian Empire garden architect Franz Schücht. Echo pavilion is the only remaining one of ten similar pavilions that were placed in the Forest-park Maksimir during the 19th century. Since 1964 the Echo pavilion has been protected by law and declared as cultural monument of garden architecture together with the whole park Maksimir, in which it is situated. Although the pavilion was restored several times (last time in 1986) it was in very bad condition. The reconstruction and preservation of the complete pavilions wooden construction were done after a careful analysis of its recent state in 2000. Restoration of the “Echo” Pavilion was started because its construction was in poor condition and because the whole pavilion was unsafe. There was a severe decay of the lower parts of the poles, particularly those faced to the North. New poles or only the new parts of the poles were made of glued spruce core surrounded by larch heartwood. Organic solvent Tebuconazole and WOODCAP products were used in wood preservation. The restoration of the Pavilion can be seen as an attempt to extend the life time of a severely damaged cultural monument, or at least in those parts of the monument where the amendments were possible. During reconstruction a monitoring system for wood moisture content at three different positions inside the roof construction was installed. Twice a year the pavilion is being carefully visually inspected and data from data logger downloaded and correctness of the equipment verified.This example of the “Echo” Pavilion is showing that moisture monitoring systems can considerably contribute to prevent cultural heritage from decay. The installed inexpensive and simple monitoring system of early warning proved to be feasible and saved costs in the conservation of wooden cultural heritage. In times of tight budgets and increasing rates of decay moisture monitoring systems will become increasingly important.

Anatomical properties of white poplar (Populus alba L.) wood have not been sufficiently investigated and quantified, whereas data on fiber characteristics will certainly define its potential as a raw material. Fiber length, double cell wall thickness and fiber lumen diameter of white poplar juvenile wood from two sites along the Drava River in Croatia were measured. Variations in fiber characteristics in radial direction (from pith to bark), within and between white poplar populations from two sites were investigated. Results indicate that fiber Rlength and double cell wall thickness varied significantly from pith to bark, within and between sites. Variation in fiber lumen diameter was non-significant only between sites. The variation in radial pattern was characterized by increase in fiber length with cambial age. Double cell wall thickness and fiber lumen diameter varied in non-consistent radial pattern. In conclusion, variation significance demonstrates nonhomogeneous wood fiber characteristics at both sites., Anatomska svojstva drva bijele topole (Populus alba L.) nedovoljno su istražena i nisu kvantificirana, a podatci o obilježjima drvnih vlakanaca zasigurno će upozoriti na potencijal tog drva kao sirovine. U radu je izmjerena duljina vlakanaca, dvostruka debljina stijenki i promjer lumena vlakanaca juvenilnog drva bijele topole s dva staništa uz rijeku Dravu. Istražene su i varijacije svojstava vlakanaca u smjeru od srčike prema kori, kao i unutar istog staništa odnosno između dvaju promatranih staništa. Rezultati pokazuju značajne varijacije duljine vlakanaca i dvostruke debljine stijenki od srčike prema kori te unutar istog staništa i između dvaju staništa. Varijacije promjera lumena vlakanaca nisu značajne samo među staništima. Radijalne su varijacije određene rastom duljine vlakanaca sa starošću drva. Dvostruka debljina stijenki i promjer lumena vlakanaca mijenjaju se prema promjenjivom modelu između godova. Zaključno, značenje varijacija upućuje na nehomogenost svojstava drvnih vlakanaca na oba staništa.

Previous articles have shown that modification of wood by citric acid (CA) improves dimensional stability and resistance of wood against fungi attack. However, chemical modification of wood also modifies its mechanical properties in some way. The compression strength of wood is one of its representative mechanical properties. Modified wood with lower values of compression strength has limited purpose. The intention of this work is to show the effect of wood modification by citric acid on the compression strength of wood. Fir wood (Abies alba Mill.) and beech wood (Fagus sylvatica L.) were impregnated by citric acid with sodium-dihydrogen-hypophosphite (NaH2PO2) as a catalyst. Part of the impregnated samples together with control samples were cured at the temperature of 140 °C for 10 hours and the remaining samples were cured in microwaves for 35 minutes. The average compression strength parallel to the grain of wood modifi ed by CA, using different regimes of curing, was compared to the strength of unmodifi ed wood. The average compression strength parallel to the grain of wood was retained after modification. In the case of fir wood, the average compression strength was even improved after modification. The results indicate that wood modified by citric acid may be considered for the purposes where compression strength properties are equally important as improved durability and dimensional stability of wood.

Gamma irradiation, which is an easy, fast and effective method for wood sterilisation, changes molecular structures not only in pest cells, but also in wood cell walls. Radiation-induced depolymerisation causes significant changes in some properties of wood crucial for restoration and for laboratory testing of wood-preservative effectiveness, as demonstrated by experimental data. The influence of gamma radiation on maximum swelling (αMAX), resistance to impact milling (RIM), and the total amount of water-soluble carbohydrates (TSC) was investigated. Cobalt (60Co) was used as a gamma source and Scots pine wood (Pinus sylvestris L.) was irradiated at doses of 30, 90 and 150 kGy. A strong linear correlation was found between TSC and radiation dosage. Leached irradiated specimens showed significantly greater TSC content than non-irradiated controls. RIM decreased significantly and linearly with increasing radiation dosage. After leaching, the linearity between these parameters improved. Gamma radiation had no significant effect on αMAX and the time elapsed after irradiation did not influence αMAX, RIM or TSC.

The article presents preliminary results of the biological durability of oil heat treated (OHT) alder wood (Alnus glutinosa) against pure cultures of rot fungi (Postia placenta and Trametes versicolor) in lab conditions. The modification was performed by heating of specimens immersed in soya oil. There were four heating regimes of different duration (6 and 10 hours) at final temperature of 180 and 200 ºC. The increase in mass (MI) caused by modification and mass loss of wood caused by fungal decay (ML) were determined. In addition, the natural durability of alder wood was determined and compared to the natural durability of beech wood as the reference wood species. After modification of alder wood at 200 °C, MI was lower than after treatment at 180 °C. MI was also lower after 10 hours of treatment than after 6 hours of treatment. The results showed significantly increased biological durability of modified alder wood against both tested fungi. The effect of OHT on increasing the biological durability of alder wood was higher against the fungus P. placenta. It seems that the fungus T. versicolor favours the remained oil after modification causing higher mass loss. The results showed that alder wood, thermally modified in soya oil by testing regimens, is not suitable for applications in use classes 3-5., U radu su prezentirani preliminarni rezultati biološke otpornosti drva johe (Alnus glutinosa) termički modificiranoga u sojinu ulju protiv čistih kultura gljiva truležnica (Postia placenta i Trametes versicolor) u laboratorijskim uvjetima metodom mini blok prema CEN TS 15083-1. Modifikacija je izvedena zagrijavanjem uzoraka uronjenih u sojino ulje sobne temperature. Četiri načina termičke modifikacije razlikovala su se po trajanju držanja drva (6 i 10 sati) na konačnoj temperaturi (180 i 200 ºC). Usto je određena i prirodna otpornost johovine u usporedbi s prirodnom otpornosti bukovine kao referentne prirodno slabo otporne vrste drva. Mjereno je povećanje mase modifikacijom (DMM) i gubitak mase djelovanjem spomenutih gljiva (GMG). Nakon modifikacije pri višoj temperaturi DMM drva johe bio je manji nego nakon modifi kacije pri nižoj temperaturi. Slično tome, dulji je tretman rezultirao nižim DMM-om nego kraći tretman. Rezultati su potvrdili povećanje biološke otpornosti modificirane johovine protiv obje testirane gljive truležnice. S povećanjem temperature modifikacije znatno se povećava biološka otpornost protiv obje gljive, dok produljenje vremena zagrijavanja ima blagi učinak povećanja biološke otpornosti. Utjecaj modifikacije na povećanje biološke otpornosti veći je protiv gljive smeđe truleži P. placenta. Utvrđeno je da je veći gubitkom mase modificiranih uzoraka djelovanjem gljive T. versicolor (u usporedbi s gubitak mase djelovanjem gljive P. placenta) najvjerojatnije nastao zbog razaranja preostalog ulja u drvu nakon modifikacije. Dokaz tome je crvena boja mikroskopskih preparata modificiranih uzoraka (postojanje lignina) te lokalna plava obojenost u lumenima traheja (nedostatak lignina). U lumenima traheja ostalo je najviše ulja nakon modifi kacije, pa se tu ujedno i najjače razvio micelij gljive bijele truleži T. versicolor, koji je, osim razgradnje ulja, djelomično uništio i lignin. Rezultati su pokazali da johovina termički modificirana u biljnom ulju, prema testiranim režimima, nije primjerena za upotrebu u razredima opasnosti 3 i višima.

Gamma radiation – as an easy, fast, and effective sterilisation method – changes molecular structures not only in pest’s living cells, but also in wooden cell walls. Radiation-induced depolymerisation causes significant changes in some properties of wood crucial for restoration and for laboratory testing the resistance of wood and wooden products against wood-destroying organisms. Overview of up to date data on the influence of gamma radiation onto some physical, mechanical and chemical properties and on biological resistance against fungal decay are presented.

Zbog mogućnosti prijenosa karantenskih štetnika daleko od svojih uobičajenih areala, pod okriljem Svjetske trgovinske organizacije WTO (World Trade Organisation) i Svjetske organizacije za hranu i poljoprivredu FAO (Food and Agriculture Organisation), izrađen je i prihvaćen Međunarod ni standard ISPM 15. Njime su predviđeni postupci tretiranja drvene ambalaže u međunarodnom prometu primjenom kojih se smanjuje rizik od unošenja i/ili širenja karantenskih štetnih organizama putem navedenog materijala. Donošenjem Pravilnika o fitosanitarnim zahtjevima kojima mora udovoljavati drve ni materijal za pakiranje u međunarodnom prometu (NN 14/06), Repu blika Hrvatska je također usvojila standard ISPM 15 u svoje za konodavstvo. Tijekom petogodišnjih aktivnosti fitosanitarni sustav je ustrojen, a 84 tvrtke su ovlaštene za samostalno provođenje toplinskog tretiranja (HT) i označavanja dr venog materijala za pakiranje. Tvrtke su dobro distribuirane po cijeloj Hrvatskoj, što omogućuje hrvatskom gospodarstvu neometani međunarodni pro-met roba. Tijekom fitosanitarnog pregleda u 67 ovlaštenih tvrtki ustanovljeno je da sve tvrtke pravilno provode toplinske tretmane, dok se glavni problemi javljaju u izradi Priručnika ovlaštene tvrtke, sljedivom vođenju dokumentacije, održavanju i ovjeravanju mjerne opreme te označavanju drvenog materijala za pakiranje u međunarodnom prometu. Uočeni nedostaci su uglavnom internog karaktera te do sada nisu uzrokovali negativne učinke u međunarodnom prometu. Slijedom zapisnika fitosanitarnog pregleda tvrtke su dužne do sljedećeg pregleda otkloniti uočene nedostatke., Because of the portability of the quarantine pests away from their usual area, under the auspices of the World Trade Organization (WTO) and the World Organization for Food and Agriculture (FAO), International standard ISPM 15 was made and accepted. ISPM 15 provides methods of treating wood packaging in international traffic which application reduces the risk of entering and / or spread of harmful quarantine organisms using the wooden material. By adoption of The rules of the phytosanitary requirements to be met by wood packaging material in international transport (Pravilnik o fitosanitarnim zahtjevima kojima mora udovoljavati drveni materijal za pakira nje u međunarodnom prometu, NN 14/06), Republic of Croatia also incorpo rated standard ISPM 15 into their legislation. During the five-year activities phytosanitary system was established, and 84 companies are authorized to independently conduct heat treatment (HT) and to mark wooden packaging materials. Companies are well distributed throughout Croatia, which allows the Croatian economy unimpeded international trade of goods. During phytosanitary inspection, in the 67 authorized companies it has been found that all the companies properly carry out the heat treatment, while the main problems arise in the development of the Manual of authorized companies, traceable records, maintaining and certifying measuring equipment and marking of wooden packaging materials in international commerce. Observed deficiencies are mainly internal in character and have not caused adverse effects in international traffic. Following record of phytosanitary inspection, companies are obliged to remove the perceived shortcomings before the next inspection.

This paper presents the results of measurement of durability of beech wood (Fagus sylvatica) modified by Citric Acid (CA) against brown rot fungus Poria placenta according to EN 113. Modification was performed by impregnation with 7.0% CA and 6.5% sodium-hypophosphite (SHP) water solution and 10-hour curing at 140 °C. The influence of thermal treatment on durability was also researched. Weight percentage gain (WPG) caused by modification, moisture content (MC) and mass loss of wood (dm) after fungal nutrition were measured. WPG of modified beech wood was 6.1% and that of thermally treated wood was -0.3%. The results showed increased durability of modified wood to be 8.3 times greater than nonmodified, while thermal treatment did not give significant durability improvement. These results indicate modification by CA as a promising alternative, but further research on optimisation of modification parameters is needed to achieve improvement of wood properties., U radu su prezentirani rezultati biološke otpornosti limunskom kiselinom modificiranog drva obične bukve (Fagus sylvatica) protiv gljive Poria placenta, a prema EN 113. Modifikacija je izvedena termokondenziranjem drvenih uzoraka impregniranih vodenom otopinom 7-postotne limunske kiseline (CA) i 6,5-postotnog natrijhipofosfita (SHP) pri 140 °C. Tijekom prvih pet minuta impregnacije uzorci su vakuumirani, a potom je u operacijski cilindar puštena otopina. Za cijelo vrijeme impregnacije primijenjen je apsolutni tlak od 2 kPa pri temperaturi od 20 °C. Navedeni uvjeti održavani su tri sata, nakon čega je slijedilo potapanje uzoraka u trajanju 18 sati pri atmosferskom tlaku. Uzorci su potom prosušeni u standardnoj klimi tijekom 48 sati, a zatim zagrijavani (termokondenzirani) u sušioniku na temperaturi 140 °C deset sati. Dodatno je kontroliran i sam utjecaj temperature na biološku otpornost. Mjereno je povećanje mase (WPG) zbog modifikacije, sadržaj vode (MC) i gubitak mase (dm) nakon djelovanja gljive. WPG bukovine modificirane limunskom kiselinom iznosio je 6,1%, a samo zagrijanih uzoraka -0,3%. Rezultati su pokazali čak 8,3 puta veću biološku otpornost bukovine modificirane limunskom kiselinom dok samo zagrijavanje nije imalo statistički značajan utjecaj na biološku otpornost. Nakon djelovanja gljiva uzorci modificirani limunskom kiselinom imali su najveći, a kontrolni uzorci najmanji sadržaj vode. Rezultati pokazuju da je modifikacija limunskom kiselinom obečavajuća alternativna metoda u zaštiti drva, no potrebna su daljnja istraživanja optimiranja koncentracija CA i SHP-a u vodenoj otopini, vremena i temperature termokondenzacije radi poboljšavanja željenih svojstava drva.