Valentin Popa - Academia.edu (original) (raw)
Papers by Valentin Popa
European Journal of Wood and Wood Products, Feb 1, 2020
In recent years, synthesis of nanoparticles using vegetal extract has gained much interest in nan... more In recent years, synthesis of nanoparticles using vegetal extract has gained much interest in nanobiotechnology. The aim of this study is the biosynthesis of silver nanoparticles (AgNPs) from silver nitrate using spruce (Picea abies L.) bark as a bioresource of cost-effective nonhazardous reducing and stabilizing compounds. The effects of various parameters such as concentration of reactants, ratio extract/silver nitrate and time of incubation on the controlled formation of AgNPs were explored. The AgNPs were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible-near infrared spectroscopy and scanning electron microscopy. A stock solution of silver nitrate (0.1 M) was prepared. Different concentrations of silver nitrate (1, 2.5, 4, and 5 mM) were prepared from the above solution, then added to 5 mL of spruce bark extract. The synthesis of AgNPs was confirmed by the change in the color of the mixtures from brown to grey. It was noticed that the synthesized nanoparticles have sizes between 0.1 and 0.5 µm (100–500 nm) with an average diameter of 0.226 µm (226 nm). The antibacterial activity of synthesized AgNPs was investigated in vitro. It was found that the most potent antibacterial activity appeared in AgNPs compared to the aqueous extract or silver nitrate.
Pulp Production and Processing, 2020
The problem of education is of particular interest in the development strategy of a nation. This ... more The problem of education is of particular interest in the development strategy of a nation. This is why most countries are concerned at the governmental level with finding the best formula for education to assist the individual in evolving positively not only in order to serve the society, but also to reach the satisfaction of a full personal achievement. Such concerns are frequent in Romania too, as since 1989 each of those over 20 Ministers of Education who came up to this decision-making position has attempted to make history with a new education law and with various reform proposals (almost 60) regarding the curriculum, the structure of the school year, the phasing of the education levels, evaluation and examination. Unfortunately, without assuring the continuity and the evaluation over time of the results of the proposed measures, most experiments have failed to produce the desired effects. Moreover, a correlation between the reforms initiated and the real situation regarding the human, material and financial resources in Romania lacks. So, at present we are witnessing attempts to imitate high-performance education systems implemented in other countries, and a total confusion of parents, students and those who are supposed to put into practice the educational strategies.
Environmental Engineering and Management Journal, 2008
In India, transportation sector is growing fast and the number of vehicles on Indian roads is inc... more In India, transportation sector is growing fast and the number of vehicles on Indian roads is increasing at a rate more than 7 percent a year. During the period of 50 years from 1951 to 2001, the number of vehicles has increased from 0.3 million to 43 million i.e. an increase of almost 143 times. This has led to overcrowded roads and noise pollution. The transportation sector is one of the major contributors to noise in urban areas, accounting to as much as 55 percent of total noise on the arterials. Interrupted traffic flow noise is associated with the typical congested conditions in the urban area and has different characteristics from the traffic noise generated by free flow traffic on rural roads. These differences arise from the various traffic flow characteristics such as heterogeneity of traffic, flow speeds etc., which is in contrast to traffic on rural roads, where the flow is generally continuous. In this paper, analytical modelling has been used for predicting road traffi...
The number of scientific journals increases with the intensification of research activity which i... more The number of scientific journals increases with the intensification of research activity which is the characteristic future of our society. This is why we need to establish criteria to evaluate the quality of the journals, scientists, universities and research institutes based on the published scientific papers. The results will allow helping governments in strategic planning to finance research activities for sustainable development and to encourage the national and international scientific cooperation. Considering the huge number of journals, there is a lot of discussion which has to lead to the best results concerning journals evaluation.
Revista de Chimie, 2020
This work assessed the qualitative and quantitative polyphenols profile in a crude ethanol extrac... more This work assessed the qualitative and quantitative polyphenols profile in a crude ethanol extract separated from spruce bark (two fractions with [0.25 and 1 mm diameter) using ultrasound assisted extraction (UAE) as a green extraction method. The evaluation of phenolic acids and condensed tannins profile was performed using instrumental (UV-VIS spectrometry), qualitative (Thin Layer Chromatography, TLC) and quantitative (HPTLC densitometry) methods. Using ultrasound assisted extraction (UAE) technique under specific parameters, the higher total phenolic content (TPC) was 29.785 mg GAE/g-1 for spruce bark fraction with particle size [0.25 mm and 14.448 mg GAE/g-1 for fraction with 1 mm diameters. The TLC assay of the crude ethanol extract was performed considering the standards: gallic, sinapic, p-coumaric and vanillic acids, catechin, epicatechin and tannic acid. Smaller material particle sizes lead to higher yield of polyphenols in ethanol extract. The quantitative evaluation by H...
Cellulose Chemistry and Technology, 2019
Shells resulting from food processing and agricultural activities, such as hard shells of apricot... more Shells resulting from food processing and agricultural activities, such as hard shells of apricot, are considered as wastes and are generally used as fuel. However, this residue shows promise as lignocellulosic feedstock for biorefineries, for its conversion to liquid fuel or bio-products. This study is dedicated to the characterization and isolation of lignin, cellulose and hemicelluloses from apricot shells (AS). The chemical composition and thermal stability of AS after chemical treatment with solvents (ethanol-toluene), cellulose, hemicelluloses and lignin were analyzed by standard methods, i.e. Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Further, almost 50.2 wt% of a water-insoluble extract was obtained after the bleaching process, which showed the removal of lignin, and the final percentages for this extraction were 50.2 ± 0.34%, 26.5 ± 0.83%, 23.7 ± 0.29% and 35 ± 1% for holocellulose, cellulose, hemicelluloses and lignin, respectively. FTIR spectroscopy evidenced the structure of lignin, cellulose and hemicelluloses. Thermal analysis and the kinetic study suggested that cellulose had higher thermal stability than the other components, with the activation energy of 289.62 kJ/mol. Thus, our results indicated the high potential of AS to be used as an environmentally friendly material in a biorefinery, as well as in the modern polymer and chemical industries.
BioResources, 2018
The effects of spruce bark crude extracts were evaluated relative to basil (Ocimum basilicum L.) ... more The effects of spruce bark crude extracts were evaluated relative to basil (Ocimum basilicum L.) plantlet development and metabolic processes (cellular division and histo-anatomical modification) involved in breeding. Natural phenolic compounds were separated as crude extracts by conventional and green extraction techniques, in a primary biorefining process, from Picea abies L. waste bark. First, the influence of phenolic compounds, in different concentrations, on the basil plants' main biosynthetic processes was analyzed. The mitotic indices and chromosomal aberrations of the plantlets were monitored. There was a significantly positive action of the studied bioproducts on basil root and stem growth, biomass accumulation, and photo-assimilating pigment synthesis. The natural polyphenols triggered an intensification of metabolic processes and cell division, yielding a high mitotic index and good development of vascular bundles. The results supported the possibility of exploiting spruce bark wastes by conversion into valuable bio-compounds, with uses as innovative products in green biotechnology, as simple growth bioregulators, for example, or for biotech crops.
Environmental Engineering and Management Journal, 2005
It is known that in the natural conditions of organic carbon cycle lignins represents the main so... more It is known that in the natural conditions of organic carbon cycle lignins represents the main source of humus formation. This complex transformation could be accelerated by chemical and biochemical modification of lignins. Along with this natural aromatic polymer, the polyphenols can be considered. Based on chemical and biochemical modification of lignins and polyphenols and the properties of resulted products they can be used to improve soil fertility and to perform different kind of bioremediations. In this review the main possibilities to manipulate these processes are presented.
cellulosechemtechnol.ro
The paper discusses the obtaining and characterization of nanoparticles based on hydroxymethyl an... more The paper discusses the obtaining and characterization of nanoparticles based on hydroxymethyl and epoxy lignin, which were tested in terms of their biocidal properties. Lignins from annual plants (wheat straw and Sarkanda grass) and commercial products (Protobind 1000, 2000, 3000), offered by Granit Recherche Developement SA Lausanne-Switzerland, were used for the reactions. Under suitable synthesis conditions, nanoparticles used for the treatment of birch veneer samples were obtained. The samples were immersed successively in 5% concentrated solutions containing copper ions and unmodified and modified lignins, dissolved in 0.1N ammonia solutions, which led to in situ complexes between the two partners. The biostability of the thus treated veneer samples was assessed by their burial in soil for 6 months, and by their characterization as to mass loss and contact angle values. The obtained results show that the treatment of birch veneer with complexes of nanoparticles with copper assures a high stability of the substrate timber products, comparatively with the unmodified products used for the same purpose.
Polyphenols in Plants, 2019
Abstract Phenolic compounds are widespread substances in plants with a special role in the metabo... more Abstract Phenolic compounds are widespread substances in plants with a special role in the metabolic processes in living organisms. This review is aimed to systematize the influence of polyphenolic compounds from different sources on the processes of plant growth and development. Crude extracts with high content in polyphenols are characterized by different concentrations and compositions, depending on the source and the agent used for their separation. Our results and the literature data highlight that polyphenolic extracts influence a series of processes, such as seed germination, plant growth and development, cell division, and biosynthesis of photosynthesizing pigments. These influences are manifested differently in plants. Thus, the inhibitory or stimulatory role of polyphenols in the plant's metabolism has been highlighted. Therefore, these aspects need to be further investigated to clarify the mechanisms of action and to establish a correlation between their structure, function, and properties.
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture, 2016
The plant kingdom is an inexhaustible source of bioactive compounds with antioxidant character. I... more The plant kingdom is an inexhaustible source of bioactive compounds with antioxidant character. It is known that, natural polyphenols are essential compounds in stimulating plant growth and development. The aim of this study was to identify the internal structure changes in maize (Zea mays L.) seedlings, under the influence of hemp shives polyphenolic extract. Hemp shives polyphenolic extract was characterized in terms of the total content of polyphenols and individual content by HPLC. Germination tests were carried out going through a standard procedure. In order to perform the histo-anatomical characterization, the vegetal material was fixed and preserved in alcohol 70%, following to be cut by hand microtome. The sections obtained were stained using double staining reagents: green - iodine and ruthenium red. It was observed, compared with the control, that hemp shives polyphenolic extract determines a good development of the root hairs and increase leading bundles number and centr...
Memoirs of the Scientific Sections of the Romanian Academy, 2020
The paper presents some peculiar aspects of the life and scientific activity of acad. Cr.I.S., se... more The paper presents some peculiar aspects of the life and scientific activity of acad. Cr.I.S., seen through the eyes of his close collaborators.
Biomass – a source of chemicals and energy for sustainable development
Cellulose Chemistry and Technology, 2005
Natural polymers are characterized by three main properties: multifunctionality, biodegradability... more Natural polymers are characterized by three main properties: multifunctionality, biodegradability and biocompatibility, which are essential for various applications that should comply with the environment. Due to the hugeavailability of the phytomass sources resulted from photosynthesis, there are several possibilities to achieve some complex composite systems based on the utilization of natural/synthetic polymer mixtures. On the other hand, it is known that hydrophilic lignocellulosic materials and hydrophobic synthetic polymers are incompatible. The compatibility between the two kinds of polymers could be achieved by modification of either the hydrophilic natural polymer or of the synthetic one. The paper discusses the results on the modification of hardwood flour chemicals by reactions with epichlorohydrin and steroyl chloride, for the introduction of modified flour into the composite materials. The modified products were characterized by FTIR spectroscopy, thermodifferential ana...
Phenolic extracts of bilberry: they protect lipid from oxidation in in vitro simulated digestion ... more Phenolic extracts of bilberry: they protect lipid from oxidation in in vitro simulated digestion conditions. ICP 2016 - XXVIIIth International Conference on Polyphenols
The present paper focused on the effect of unmodified and modified lignins and copper ions on the... more The present paper focused on the effect of unmodified and modified lignins and copper ions on the interaction between birch veneer and some biocides. The aim of the present study was to modify commercial lignins (Protobind 1000, Protobind 2000, Protobind 3000) by the hydroxymethylation reaction in an alkaline medium and to describe the lignin derivatives by chemical, spectral (H NMR) and thermal analyses (TG). The studies revealed some functional changes, which are correlated with both the different reactivity of lignins and the reaction conditions. Also, lignin derivatives were observed by thermal analysis, which allowed establishing a correlation between the modification degree and the thermal stability. Treatments with unmodified and hydroxymethylated lignins were applied to birch veneer strips by immersing them in copper chloride solutions. The lignin products were dissolved in 0.1 N ammonia solution of 5% concentration. The biostability of the treated veneer was tested by buryi...
European Journal of Wood and Wood Products, Feb 1, 2020
In recent years, synthesis of nanoparticles using vegetal extract has gained much interest in nan... more In recent years, synthesis of nanoparticles using vegetal extract has gained much interest in nanobiotechnology. The aim of this study is the biosynthesis of silver nanoparticles (AgNPs) from silver nitrate using spruce (Picea abies L.) bark as a bioresource of cost-effective nonhazardous reducing and stabilizing compounds. The effects of various parameters such as concentration of reactants, ratio extract/silver nitrate and time of incubation on the controlled formation of AgNPs were explored. The AgNPs were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible-near infrared spectroscopy and scanning electron microscopy. A stock solution of silver nitrate (0.1 M) was prepared. Different concentrations of silver nitrate (1, 2.5, 4, and 5 mM) were prepared from the above solution, then added to 5 mL of spruce bark extract. The synthesis of AgNPs was confirmed by the change in the color of the mixtures from brown to grey. It was noticed that the synthesized nanoparticles have sizes between 0.1 and 0.5 µm (100–500 nm) with an average diameter of 0.226 µm (226 nm). The antibacterial activity of synthesized AgNPs was investigated in vitro. It was found that the most potent antibacterial activity appeared in AgNPs compared to the aqueous extract or silver nitrate.
Pulp Production and Processing, 2020
The problem of education is of particular interest in the development strategy of a nation. This ... more The problem of education is of particular interest in the development strategy of a nation. This is why most countries are concerned at the governmental level with finding the best formula for education to assist the individual in evolving positively not only in order to serve the society, but also to reach the satisfaction of a full personal achievement. Such concerns are frequent in Romania too, as since 1989 each of those over 20 Ministers of Education who came up to this decision-making position has attempted to make history with a new education law and with various reform proposals (almost 60) regarding the curriculum, the structure of the school year, the phasing of the education levels, evaluation and examination. Unfortunately, without assuring the continuity and the evaluation over time of the results of the proposed measures, most experiments have failed to produce the desired effects. Moreover, a correlation between the reforms initiated and the real situation regarding the human, material and financial resources in Romania lacks. So, at present we are witnessing attempts to imitate high-performance education systems implemented in other countries, and a total confusion of parents, students and those who are supposed to put into practice the educational strategies.
Environmental Engineering and Management Journal, 2008
In India, transportation sector is growing fast and the number of vehicles on Indian roads is inc... more In India, transportation sector is growing fast and the number of vehicles on Indian roads is increasing at a rate more than 7 percent a year. During the period of 50 years from 1951 to 2001, the number of vehicles has increased from 0.3 million to 43 million i.e. an increase of almost 143 times. This has led to overcrowded roads and noise pollution. The transportation sector is one of the major contributors to noise in urban areas, accounting to as much as 55 percent of total noise on the arterials. Interrupted traffic flow noise is associated with the typical congested conditions in the urban area and has different characteristics from the traffic noise generated by free flow traffic on rural roads. These differences arise from the various traffic flow characteristics such as heterogeneity of traffic, flow speeds etc., which is in contrast to traffic on rural roads, where the flow is generally continuous. In this paper, analytical modelling has been used for predicting road traffi...
The number of scientific journals increases with the intensification of research activity which i... more The number of scientific journals increases with the intensification of research activity which is the characteristic future of our society. This is why we need to establish criteria to evaluate the quality of the journals, scientists, universities and research institutes based on the published scientific papers. The results will allow helping governments in strategic planning to finance research activities for sustainable development and to encourage the national and international scientific cooperation. Considering the huge number of journals, there is a lot of discussion which has to lead to the best results concerning journals evaluation.
Revista de Chimie, 2020
This work assessed the qualitative and quantitative polyphenols profile in a crude ethanol extrac... more This work assessed the qualitative and quantitative polyphenols profile in a crude ethanol extract separated from spruce bark (two fractions with [0.25 and 1 mm diameter) using ultrasound assisted extraction (UAE) as a green extraction method. The evaluation of phenolic acids and condensed tannins profile was performed using instrumental (UV-VIS spectrometry), qualitative (Thin Layer Chromatography, TLC) and quantitative (HPTLC densitometry) methods. Using ultrasound assisted extraction (UAE) technique under specific parameters, the higher total phenolic content (TPC) was 29.785 mg GAE/g-1 for spruce bark fraction with particle size [0.25 mm and 14.448 mg GAE/g-1 for fraction with 1 mm diameters. The TLC assay of the crude ethanol extract was performed considering the standards: gallic, sinapic, p-coumaric and vanillic acids, catechin, epicatechin and tannic acid. Smaller material particle sizes lead to higher yield of polyphenols in ethanol extract. The quantitative evaluation by H...
Cellulose Chemistry and Technology, 2019
Shells resulting from food processing and agricultural activities, such as hard shells of apricot... more Shells resulting from food processing and agricultural activities, such as hard shells of apricot, are considered as wastes and are generally used as fuel. However, this residue shows promise as lignocellulosic feedstock for biorefineries, for its conversion to liquid fuel or bio-products. This study is dedicated to the characterization and isolation of lignin, cellulose and hemicelluloses from apricot shells (AS). The chemical composition and thermal stability of AS after chemical treatment with solvents (ethanol-toluene), cellulose, hemicelluloses and lignin were analyzed by standard methods, i.e. Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Further, almost 50.2 wt% of a water-insoluble extract was obtained after the bleaching process, which showed the removal of lignin, and the final percentages for this extraction were 50.2 ± 0.34%, 26.5 ± 0.83%, 23.7 ± 0.29% and 35 ± 1% for holocellulose, cellulose, hemicelluloses and lignin, respectively. FTIR spectroscopy evidenced the structure of lignin, cellulose and hemicelluloses. Thermal analysis and the kinetic study suggested that cellulose had higher thermal stability than the other components, with the activation energy of 289.62 kJ/mol. Thus, our results indicated the high potential of AS to be used as an environmentally friendly material in a biorefinery, as well as in the modern polymer and chemical industries.
BioResources, 2018
The effects of spruce bark crude extracts were evaluated relative to basil (Ocimum basilicum L.) ... more The effects of spruce bark crude extracts were evaluated relative to basil (Ocimum basilicum L.) plantlet development and metabolic processes (cellular division and histo-anatomical modification) involved in breeding. Natural phenolic compounds were separated as crude extracts by conventional and green extraction techniques, in a primary biorefining process, from Picea abies L. waste bark. First, the influence of phenolic compounds, in different concentrations, on the basil plants' main biosynthetic processes was analyzed. The mitotic indices and chromosomal aberrations of the plantlets were monitored. There was a significantly positive action of the studied bioproducts on basil root and stem growth, biomass accumulation, and photo-assimilating pigment synthesis. The natural polyphenols triggered an intensification of metabolic processes and cell division, yielding a high mitotic index and good development of vascular bundles. The results supported the possibility of exploiting spruce bark wastes by conversion into valuable bio-compounds, with uses as innovative products in green biotechnology, as simple growth bioregulators, for example, or for biotech crops.
Environmental Engineering and Management Journal, 2005
It is known that in the natural conditions of organic carbon cycle lignins represents the main so... more It is known that in the natural conditions of organic carbon cycle lignins represents the main source of humus formation. This complex transformation could be accelerated by chemical and biochemical modification of lignins. Along with this natural aromatic polymer, the polyphenols can be considered. Based on chemical and biochemical modification of lignins and polyphenols and the properties of resulted products they can be used to improve soil fertility and to perform different kind of bioremediations. In this review the main possibilities to manipulate these processes are presented.
cellulosechemtechnol.ro
The paper discusses the obtaining and characterization of nanoparticles based on hydroxymethyl an... more The paper discusses the obtaining and characterization of nanoparticles based on hydroxymethyl and epoxy lignin, which were tested in terms of their biocidal properties. Lignins from annual plants (wheat straw and Sarkanda grass) and commercial products (Protobind 1000, 2000, 3000), offered by Granit Recherche Developement SA Lausanne-Switzerland, were used for the reactions. Under suitable synthesis conditions, nanoparticles used for the treatment of birch veneer samples were obtained. The samples were immersed successively in 5% concentrated solutions containing copper ions and unmodified and modified lignins, dissolved in 0.1N ammonia solutions, which led to in situ complexes between the two partners. The biostability of the thus treated veneer samples was assessed by their burial in soil for 6 months, and by their characterization as to mass loss and contact angle values. The obtained results show that the treatment of birch veneer with complexes of nanoparticles with copper assures a high stability of the substrate timber products, comparatively with the unmodified products used for the same purpose.
Polyphenols in Plants, 2019
Abstract Phenolic compounds are widespread substances in plants with a special role in the metabo... more Abstract Phenolic compounds are widespread substances in plants with a special role in the metabolic processes in living organisms. This review is aimed to systematize the influence of polyphenolic compounds from different sources on the processes of plant growth and development. Crude extracts with high content in polyphenols are characterized by different concentrations and compositions, depending on the source and the agent used for their separation. Our results and the literature data highlight that polyphenolic extracts influence a series of processes, such as seed germination, plant growth and development, cell division, and biosynthesis of photosynthesizing pigments. These influences are manifested differently in plants. Thus, the inhibitory or stimulatory role of polyphenols in the plant's metabolism has been highlighted. Therefore, these aspects need to be further investigated to clarify the mechanisms of action and to establish a correlation between their structure, function, and properties.
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture, 2016
The plant kingdom is an inexhaustible source of bioactive compounds with antioxidant character. I... more The plant kingdom is an inexhaustible source of bioactive compounds with antioxidant character. It is known that, natural polyphenols are essential compounds in stimulating plant growth and development. The aim of this study was to identify the internal structure changes in maize (Zea mays L.) seedlings, under the influence of hemp shives polyphenolic extract. Hemp shives polyphenolic extract was characterized in terms of the total content of polyphenols and individual content by HPLC. Germination tests were carried out going through a standard procedure. In order to perform the histo-anatomical characterization, the vegetal material was fixed and preserved in alcohol 70%, following to be cut by hand microtome. The sections obtained were stained using double staining reagents: green - iodine and ruthenium red. It was observed, compared with the control, that hemp shives polyphenolic extract determines a good development of the root hairs and increase leading bundles number and centr...
Memoirs of the Scientific Sections of the Romanian Academy, 2020
The paper presents some peculiar aspects of the life and scientific activity of acad. Cr.I.S., se... more The paper presents some peculiar aspects of the life and scientific activity of acad. Cr.I.S., seen through the eyes of his close collaborators.
Biomass – a source of chemicals and energy for sustainable development
Cellulose Chemistry and Technology, 2005
Natural polymers are characterized by three main properties: multifunctionality, biodegradability... more Natural polymers are characterized by three main properties: multifunctionality, biodegradability and biocompatibility, which are essential for various applications that should comply with the environment. Due to the hugeavailability of the phytomass sources resulted from photosynthesis, there are several possibilities to achieve some complex composite systems based on the utilization of natural/synthetic polymer mixtures. On the other hand, it is known that hydrophilic lignocellulosic materials and hydrophobic synthetic polymers are incompatible. The compatibility between the two kinds of polymers could be achieved by modification of either the hydrophilic natural polymer or of the synthetic one. The paper discusses the results on the modification of hardwood flour chemicals by reactions with epichlorohydrin and steroyl chloride, for the introduction of modified flour into the composite materials. The modified products were characterized by FTIR spectroscopy, thermodifferential ana...
Phenolic extracts of bilberry: they protect lipid from oxidation in in vitro simulated digestion ... more Phenolic extracts of bilberry: they protect lipid from oxidation in in vitro simulated digestion conditions. ICP 2016 - XXVIIIth International Conference on Polyphenols
The present paper focused on the effect of unmodified and modified lignins and copper ions on the... more The present paper focused on the effect of unmodified and modified lignins and copper ions on the interaction between birch veneer and some biocides. The aim of the present study was to modify commercial lignins (Protobind 1000, Protobind 2000, Protobind 3000) by the hydroxymethylation reaction in an alkaline medium and to describe the lignin derivatives by chemical, spectral (H NMR) and thermal analyses (TG). The studies revealed some functional changes, which are correlated with both the different reactivity of lignins and the reaction conditions. Also, lignin derivatives were observed by thermal analysis, which allowed establishing a correlation between the modification degree and the thermal stability. Treatments with unmodified and hydroxymethylated lignins were applied to birch veneer strips by immersing them in copper chloride solutions. The lignin products were dissolved in 0.1 N ammonia solution of 5% concentration. The biostability of the treated veneer was tested by buryi...