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Durability-based designs with timber require reliable information about the wood properties and how they affect its performance under variable exposure conditions. This study aimed at utilizing a material resistance model (Part 2 of this publication) based on a dose–response approach for predicting the relative decay rates in above-ground situations. Laboratory and field test data were, for the first time, surveyed globally and used to determine material-specific resistance dose values, which were correlated to decay rates. In addition, laboratory indicators were used to adapt the material resistance model to in-ground exposure. The relationship between decay rates in-and above-ground, the predictive power of laboratory indicators to predict such decay rates, and a method for implementing both in a service life prediction tool, were established based on 195 hardwoods, 29 softwoods, 19 modified timbers, and 41 preservative-treated timbers.

Service life planning with timber requires reliable models for quantifying the effects of exposure-related parameters and the material-inherent resistance of wood against biotic agents. The Meyer-Veltrup model was the first attempt to account for inherent protective properties and the wetting ability of wood to quantify resistance of wood in a quantitative manner. Based on test data on brown, white, and soft rot as well as moisture dynamics, the decay rates of different untreated wood species were predicted relative to the reference species of Norway spruce (Picea abies). The present study aimed to validate and optimize the resistance model for a wider range of wood species including very durable species, thermally and chemically modified wood, and preservative treated wood. The general model structure was shown to also be suitable for highly durable materials, but previously defined maximum thresholds had to be adjusted (i.e., maximum values of factors accounting for wetting ability and inherent protective properties) to 18 instead of 5 compared to Norway spruce. As expected, both the enlarged span in durability and the use of numerous and partly very divergent data sources (i.e., test methods, test locations, and types of data presentation) led to a decrease in the predictive power of the model compared to the original. In addition to the need to enlarge the database quantity and improve its quality, in particular for treated wood, it might be advantageous to use separate models for untreated and treated wood as long as the effect of additional impact variables (e.g., treatment quality) can be accounted for. Nevertheless, the adapted Meyer-Veltrup model will serve as an instrument to quantify material resistance for a wide range of wood-based materials as an input for comprehensive service life prediction software.

Elektroniskā versija nesatur pielikumus, Promocijas darbā „Koksnes brūnā trupe: bazīdijsēnes un to destruktīvā iedarbība uz lignocelulozi” pētīta koksnes trupes sēņu izplatība un daudzveidība Latvijas mežu biotopos, kā arī Latvijas un Maķedonijas celtniecības koksnē. Laboratorijas apstākļos ar ķīmiskām un fizikālām metodēm pētīts brūnās trupes sēņu izraisītās koksnes degradācijas mehānisms, lai, pamatojoties uz ķīmisko komponentu un struktūras izmaiņām, raksturotu šī procesa dinamiku. Latvijas mežu biotopos atrastas 144 koksnes trupes sēņu sugas (Basidiomycota). No tām 14 sugas ir retas, bet 22 trupes sēnes Latvijā ir reģistrētas pirmo reizi. Vislielākais sēņu skaits un pirmo reizi reģistrēto sugu skaits tika atrasts dabas liegumu teritorijās. 16% no reģistrēto sugu skaita pieder brūnās trupes sēnēm, pārējās (84%) - baltās trupes sēnēm. Latvijas celtniecības koksnē pēc izplatības biežuma izteikti dominēja brūnās trupes sēnes (86% gadījumu), bet Maķedonijas kultūrvēstures pieminekļos - baltās trupes sēnes (84% gadījumu), kas saistāms ar skujkoku materiālu tradicionālu izmantošanu Latvijas celtnēs, un lapkoku izmantošanu Maķedonijas celtnēs. Visbiežāk sastopamā brūnās trupes sēne Latvijas celtniecības koksnē ir Serpula lacrymans, kas konstatēta 56% gadījumu, kamēr Maķedonijas celtnēs šī sēne līdz šim nav atrasta. S. lacrymans dabā nav konstatēta ne Latvijā, ne Maķedonijā. Mūsu eksperimentos izmantoto koksnes paraugu degradācijas mehānisma izpēte deva iespēju raksturot un nodalīt trīs posmus koksnes brūnās trupes procesā: agrīnā, pamatstadija un noslēguma stadija. Agrīnā stadija (6-10 dienas) ir kritiskais posms, kurā traheīdu lumeni ir inficēti ar sēnes hifām, notiek lignīna oksidatīva modifikācija un relatīvās koncentrācijas pieaugums uz polisaharīdu sašķelšanas rēķina, celulozes polimerizācijas pakāpes strauja samazināšanās, hemiceluložu glikomannānu noārdīšana, bet masas zudumi vēl nav novērojami. Pamatstadijā (20 - 90 dienas) notiek modificētā lignīna repolimerizācija, jaunu mikroporu veidošanās, hemiceluložu acetātgrupu noārdīšana, polisaharīdu degradācijas produktu patēriņš, ko raksturo pieaugoši koksnes masas zudumi. Noslēguma stadiju (> 90 dienas) raksturo koksnes šūnas sekundārās sienas plaša degradācija ar lieliem masas zudumiem. Degradācijas agrīnajā stadijā uz koksnes šūnu, acīmredzot, vispirms iedarbojas sēņu veidotie ekstracelulārie reaktīvie skābekļa savienojumi (RSS), bet vēlāk, pamata un noslēguma stadijās, notiek enzimātiska koksnes šūnas noārdīšana. Bojātu koksnes šūnu ķīmisko un fizikālo analīžu rezultāti atklāja atšķirības starp brūnās trupes sēnēm, kas acīmredzot saistāmas ar sēņu celulolītisko un/ vai ligninolītisko sistēmu īpatnībām un to iedarbību uz koksnes šūnas komponentiem. Pētījuma rezultāti ir praktiski izmantojami koksnes aizsardzībā, parādot, ka nepieciešams atrast veidu, kā inhibēt sēņu izdalītos RSS, piemēram, paaugstinot koksnes pH, vai izmantojot savienojumus ar antioksidantu īpašībām, vai kavējot RSS reakcijas ar koksnē esošajiem dzelzs joniem. Darba rezultāti izmantoti degradācijas procesu izpētes metožu izstrādei un jaunu koksnes aizsardzības līdzekļu efektivitātes pārbaudei. Darbs ir uzrakstīts latviešu valodā. Darba 120 lappušu apjomu veido: ievads, literatūras apskats, kopsavilkums, darba mērķis un uzdevumi, eksperimentālā daļa, rezultāti un diskusija, secinājumi, aizstāvāmās tēzes, literatūras saraksts un pielikums. Darbā ir iekļauti 43 attēli, 12 tabulas un 123 literatūras avoti. Darbs izstrādāts no 1998. līdz 2008. gadam Latvijas Valsts Koksnes ķīmijas institūtā sadarbībā ar Latvijas Universitāti, Latvijas Dabas muzeju, Maķedonijas Sv. Kirila un Metodija Universitāti, Igaunijas Ķīmiskās fizikas un biofizikas institūtu, Tallinas Tehnisko universitāti un Vācijas Federālo mežsaimniecības un koksnes pētījumu centru., In the Doctoral theses “Wood Brown-Rot: Basidiomycetes and their Destructive Action on Lignocellulose”, the prevalence and diversity of wood-rot fungi in Latvian forest biotopes as well as Latvian and Macedonian construction wood was investigated. In laboratory conditions, applying chemical and physical methods, the wood degradation mechanism caused by brown-rot fungi was investigated so that, based on the changes in the chemical components and structure, to characterise the dynamics of this process. In Latvian forest biotopes, 144 species of wood-rot fungi (Basidiomycota) were found. From them, 14 species are rare, while 22 species are registered for the first time in Latvia. The greatest number of fungi and the number of the species registered for the first time are found in the territories of natural restricted areas. 16% of the registered species pertains to brown-rot fungi, while the rest of them (84%) belong to white-rot fungi. In Latvian construction wood, in terms of prevalence, brown-rot fungi dominate markedly (86% cases), while, in Macedonian cultural monuments, white-rot fungi prevail (84% cases), which is connected with the traditional use of coniferous wood materials in Latvian buildings and the use of deciduous wood in Macedonian buildings. The most commonly occurring brown-rot fungus in Latvian construction wood is Serpula lacrymans, which is found in 56% cases, while this fungus has not yet been found in Macedonian buildings. In nature, S. lacrymans is found neither in Latvia nor in Macedonia. The study of the mechanism of degradation of the wood samples used in our experiments made it possible to characterise and separate three stages in the wood brown-rot process: early stage, basic stage and final stage. The early stage (6-10 days) is a critical one, in which tracheid lumens are infected with fungal hyphae, lignin oxidative modification, and the relative increase in concentration at the expense of polysaccharides cleavage, a dramatic decrease in the cellulose polymerisation degree, and the degradation of hemicellulose glucomannanes occur, while mass losses are not yet observed. At the basic stage (20-90 days) repolymerisation of the modified lignin, formation of new micropores, degradation of hemicellulose acetate groups, and consumption of polysaccharide degradation products occur, which is characterised by the increasing wood mass losses. The final stage (> 90 days) is characterised by the extensive degradation of the wood cell secondary wall with great mass losses. At the early stage of degradation, the wood cells are obviously firstly influenced by the reactive oxygen species (ROS) that are formed by the fungi, while later, at the basic and final stages, enzymatic degradation of wood cells occurs. The results of the chemical and physical analysis of the damaged wood cells have revealed distinctions among the brown-rot fungi, which is obviously connected with the peculiarities of the cellulolytic and/or ligninolytic systems and their action on wood cell components. The results of the studies are practically applicable in wood protection, indicating that it is necessary to find a way to inhibit the ROS released by the fungi, for example, by increasing the wood pH or using compounds with antioxidant properties or hampering the ROS reactions with the iron ions present in wood. The results of the work are used to develop methods for investigating degradation processes and testing of efficiency of new wood preservatives. The work is written in Latvian. The 120 page volume of the work is comprised by the introduction, literature survey, summary, the work’s objective and tasks, experimental, results and discussion, conclusions, defended theses, references and annex. The work includes 43 figures, 12 tables and 123 references. The work has been developed from 1998 to 2008 at the Latvian State Institute of Wood Chemistry in cooperation with the Univers

Šobrīd pasaulē tiek pievērsta liela uzmanība hitozāna lietošanai pārtikā, biomedicīnā un lauksaimniecībā, kā arī iespēja ar to aizvietot kaitīgas ķīmiskās vielas. Darbā tiek pētīti piemērotākie sēņu kultivēšanas parametri, lai rezultātā iegūtu pēc iespējas lielāku biomasas daudzumu. Kā arī aplūkots jautājums, kura no darbā minētajām bazīdijsēnēm, būtu piemērotākā turpmākajam darbam ar hitozāna izdalīšanu un pielietošanu olu kastu mitruma izturības pastiprināšanā, kura vietā šobrīd izmanto putu polistirola kastes vai kartona kastes, kas ir apstrādātas ar ķīmiskajām vielām. Tika novērots, ka piemērotākā bazīdijsēne, no kuras tiek iegūts lielākais biomasas daudzums, kā arī lielākais hitozāna Ⅱ procents ir Phanerochaete chrysosporium. Ar FTIR spektroskopiju un elementu analīzi noteikta hitozāna Ⅰ un hitozāna Ⅱ esamība paraugos., Nowadays the world is paying more attention to the use of chitosan, both in food and biomedicine as well as agriculture, along with its wide potential to replace harmful chemicals. The most suitable mushroom cultivation parameters were studied to obtain as much biomass as possible. We also investigated which of the basidiomycetes mentioned in the work would be the most suitable for further work with chitosan and its application in increasing the moisture resistance of egg cartons, now we are using foam polystyrene boxes or cardboard boxes that have been chemically modified. It was observed that Phanerochaete chrysosporium had the largest amount of biomass, and the highest percentage of chitosan. The presence of chitosan Ⅰ and chitosan II in the samples is determined by FTIR spectroscopy and elemental analysis.

Nemainīga globāla problēma ir plastmasas piesārņojums, tādēļ pēdējā laikā aktualizējušies ekoloģiski iepakojuma materiāli no micēlija un augu biomasas. Pētījumā tika izveidoti sējas kaņepju spaļu, āra bērza ēveļskaidu un zāģskaidu un Trametes versicolor micēlija mikokompozīti ar pievienotām kviešu klijām un bērza mizu. Tika izvērtēta substrāta granulometrijas un sastāva ietekme uz mikokompozīta spiedes stiprību, ūdens uzsūcamību un noturību pret pelējumu. Labāko micēlija augšanu un mehāniskās uzrādīja paraugi ar pievienotām klijām, pazeminātu ūdens absorbciju – bērza mizu saturošie paraugi, pret pelējumu visiem paraugiem bija ļoti zema noturība. Būtiskāk par granulometriju bija micēlija daudzums paraugā. Šis ir pirmais pētījums, kurā izmantotas bērza ēveļskaidas, norādīta pelējuma noturība un sēnes biomasas daudzums MK paraugā., Plastic waste is an ongoing global issue, therefore eco-friendly packaging from mycelium and plant biomass has become an interesting topic. In this study mycelium biocomposites from hemp shives, birch shavings and sawdust and Trametes versicolor mycelium with wheat bran and birch bark additives were made. Granulometric properties and substrate composition efffect on mycocomposite compression strength, water absorption and mold resistance were evalued. Best mycelial growth and mechanical performance was observed in samples with added bran, reduced water absorption – samples with birch bark, but all samples had very low mold resistance. Level of mycelium growth was of higher importance than granulometry. This is the first study in which birch shavings are used, mold resistance properties and fungal biomass are assessed in the MK sample.

Organomālam piemīt antimikrobiālas īpašības un tas ir potenciāls materiāls koksnes aizsardzībā pret trupes sēnēm. Darbā pētīta divu veidu organomāla, kura sastāvā ir trimetiloktadecilamonija hlorīds, ietekme uz sēnēm Coniophora puteana un Trametes versicolor, kā arī organomāla piedevas fenola-formaldehīda sveķu līmei un impregnēšanas filmai spēja nodrošināt bērza saplākšņa ilgizturību pret koksnes trupes sēnēm. Sarkanais organomālsuzrādīja labākas inhibitorās spējas pret trupes sēnēm iesala-agara barotnē nekā baltais organomāls, tādēļ tas tika izvēlēts kā piedeva bērza saplāksnim. Pēc standartiem NF B 51-295 (lieces robežstiprība) un LVS ENV 12038:2002 (masas zudums) iegūtajos datos konstatēts, ka eksperimentāli laminēts bērza saplāksnis ir izturīgāks pret trupes sēnēm nekā eksperimentāli laminēts saplāksnis ar organomāla piedevu. Noteikts, ka C. puteana degradē saplāksni efektīvāk nekā T. versicolor. Neviens no četriem testētajiem bērza saplākšņa veidiem nav uzskatāms par pilnībā izturīgu pret trupes sēnēm, jo to masas zudums pārsniedz 3 %. Salīdzinot divu izmēru paraugus katrā no standartiem, konstatēts, ka paraugu izmērs ietekmē iegūtos rezultātus. Kopumā secināts, ka organomāla piedeva fenola-formaldehīda sveķu līmei un impregnēšanas filmai nenodrošina efektīvu bērza saplākšņa aizsardzību pret baltās un brūnās trupes sēnēm., Organoclay is a material with antimicrobial properties and it has the potential to be used for protection against wood degrading fungi. This study examines the effect of two types of organoclay that contain trimethyloctadecylammonium chloride on Coniophora puteana and Trametes versicolor. Furthermore, the effectiveness to provide protection to birch plywood against wood-decay fungi with an organoclay additive in phenol-formaldehyde resin glue and impregnation film was also evaluated. The red organoclay had better inhibitory properties against wood-decay fungi than the white organoclay when added to a malt extract-agar medium. Based on the data from standards NF B 51-295 (bending strength test) and LVS ENV 12038:2002 (mass loss test), our results show that experimentally laminated plywood is more durable against wood-decay fungi than experimentally laminated plywood with an organoclay additive. It has been found that C. puteana degrades plywood more efficiently than T. versicolor. None of the four tested types of plywood was fully resistant against decay fungi due to their mass loss being greater than 3 %. Comparing samples with two different sizes for each of the standards, it was found that sample size affects the results. In conclusion, the results show that the organoclay additive in phenol-formaldehyde resin glue and impregnation film does not provide effective protection for birch plywood against white and brown rot fungi.