فصلنامه پژوهشهای علوم و فناوری چوب و جنگل
سال بیست و ششم شماره 2 (تابستان 1398)

Street trees in urban green space, despite all the benefits, any defect due to old tree age, loss of tree resistance because of the industrialization, population density and pollution of the big cities, as well as repeated droughts, can lead to the risk of personal injury or damage to property. Therefore, the importance of exploring and identifying hazardous trees has increased the in the large cities. For this propose, the estimation of the risk possibility of plane trees (Plantanus orientalis L.) in the green space of Abbasabad-Abad in Isfahan and their fall risk model prediction was done using Artificial Neural Network.

Isfahan was studied, using data coming from a full survey method, and using quantitative tree body proportions and few risk factors (qualitative or imperfect properties). Following coining the share of each of the hazard criteria and their ratio importance indices One-way ONOVA test compared of the number of trees in different risk levels. Then, all the trees scored via the biased levels of their risk levels. Accordingly, based on the weighted scores, they were divided into five hazardous categories according. To develop an understanding of the quantitative variables, risk factors, the weight parameters and hazard classes, we carried out a principle component analysis (PCA) and a multi-layer perceptron (MLP) network procedure.

The results from the proportion of each hazard index reviled the importance of the the importance of the structural tree weakness (61%), root problems (59%), and trunk and root wounds (55%). Also, results of One-way ONOVA test, showed the risk levels of the planted trees can be significantly classified into four classes of: with no risk or healthy, low, moderate and high risk classes, at one percent error level. The results of Duncan's mean test showed that the number of trees in no risk and low risk classes were significantly higher than the other classes at one percent error level. The results from the PCA indicated that the first and second components explained 41.40 percent of the total variation. The risk and weighting parameters of the wound on the trunk and root, contact power lines, root problems were highly and positively correlated. In general, the two variables of the root problems trunk as well as root wounding were among the most important variables in term of risk assessment of the plane trees. The high coefficient of determination values of training, validation, verification and finally all neural network data (0.927, 0.930, 0.930, and 0.927) and the least mean square error values (training data = 0.186, verification 0.196 and validation = 0.169) indicated, the accuracy desirability of the artificial neural network in the prediction of the risk classes of street side trees.

Root and wound problems have the greatest portion in the risk of Platanus orientalis L. and, based on the classification of trees, are currently in low and very low risk, but they are capable of becoming dangerous trees in the future. In general preventive and corrective measures are proposed for low and intermediate risk trees. Regarding the optimal performance of the Neural Network for the classification of the hazardous Platanus orientalis L. trees in the urban green space, it is introduced as a prediction model in evaluating the probability of fallen trees.

This study was conducted in order to evaluate and compare the morphological traits of species leaflet, genotypes and inter-species hybrids of walnut tree in the Research Center of Kamal-Shahr, Karaj, Iran, Horticultural Research station, Seed and Plant Improvement Institute. Morphological characteristics are one of the first and most widely used markers that have always been considered by botanists in the past. In this regard, morphological traits of leaf have a special place in the classification of plants. The importance of morphological characteristics is such an extent that the study of them can be helpful to process genetic diversity in plants. Using these markers, species and even clones within a species can be distinguished from one another.

Evaluation of traits from following genotypes was performed with sampling in the summer from the leaves that were grown fully: eight genotypes of black walnut (N1, N2, N3, N4, N5, N6, N7, N8), seven cultivars / genotypes of Iranian walnut (Seer Damavand, Jamal, Chandler, Hartley, Pedro, Ronde de Montignac, B21 and K72), five genotypes of inter-specific hybrids (J. hindsii × J. nigra) and four genotypes of inter-specific hybrids (J. hindsii × J. regia) and a genotype of J. hindsii species. In total, 14 traits were evaluated including 7 quantitative traits (length and width of leaves (a and b), leaf width (e), leaflet length (f), petiole length (c), number and leaf area) and 7 qualitative traits (shape of the leaflet, leaf edge, leaf and petiole color, time of opening leaf bud, having wool, time of falling leaf and main petiole durability).

The results indicated that there was much morphological diversity among above species and hybrids. Statistical results showed that this species can be distinguished with selected traits.

The highest leaf area was belonged to B21 genotype of Iranian walnut species with 336.3 cm2 and the lowest leaf area was measured for N8 genotype of black walnut with 76.2 cm2. The average of quantitative traits for leaf samples showed that Iranian walnut cultivars had the maximum mean of leaf length and width and black walnut had the minimum length and width of leaf. The mean of maximum width and length of leaflet was observed in Iranian walnut and the lowest leaflet width was observed in paradox (J. hindsii x J. regia) inter-specific hybrid. The minimum of leaflet length were measured in black walnut. Among the evaluated species, the minimum and maximum number of leaflets was achieved in Iranian walnut and J. hindsii species, respectively. Genotypes were studied and grouped using cluster analysis and based on quantitative and qualitative characteristics of leaves. The genotypes were separated into three distinct clusters. The first cluster includes: six different genotypes of Black Walnut, J. hindsii species and inter-specific hybrids of Royal and paradox, a second cluster includes the cultivar of Iranian walnut and third cluster includes (B21) genotypes of Iranian walnuts.

One of the most important conservation actions that can be taken in disturbed forests is the development of enclosed areas that can substantially impact the structure and composition of vegetation. The main goal of forest management plans is to maintain the natural structure of stands. Yew is one of the most important and threatened tree species in the Arasbaran region in northwestern Iran.

In this research, we assessed the structural characteristics and composition of yew forest communities using the nearest neighbor and full callipering methods at three sites with different management histories. Within a one-hectare sampling area, tree species identity, diameter, height, and crown diameter were measured. In each of these sampling areas, 56 sample points were surveyed in a 25 m × 25 m grid for trees species identity, diameter, height, and distance from reference to neighbor trees. To quantify the structural characteristics in areas of different conservation status, some indices calculated including mingling, distance to neighbor, diameter and height differentiation, uniform angle, and Clark Evans.

The average height of yew trees at the long-term sites SKA and SVA was 5.1 and 4.8 m respectively. These trees were located in the lower layer. In the short-term site (SKU), however, yew trees (4.04 m) had approximately the same height as other trees (4.3 m). Results revealed that four species – hornbeam (68%), maple (8%), yew (7%), and oak (5.2%) composed 88% of tree species. The majority of trees had a low distance (2–3 m) between neighbors. Due to the high density of trees in the sites with a long-term conservation period (SKA and SVA), a low percentage of trees had mean distance more than 5 meters. Mean of distance to neighbor (Di) index for long-term and short-term sites were 3.8 and 5.14, respectively. The mean TDi for long-term and short-term conservation areas was 0.59 and 0.06, respectively. The uniform angle index showed that there was no class value 1 at all three sites. In the long-term enclosed area, Clark Evans index was 1.18. In short term-enclosed areas, it was less than 1 (0.82). At all sites, yew trees were in the least vital class.

Reducing tree density and basal area of other species will lend strength to yew trees in the studied sites. However, because yew trees need moderate light conditions, excessive decreases in the tree density can be detrimental. In order to optimize the management of forest resources, it is essential to get the correct information about the structure of forest stands. It is important to obtain enough information about the forest stand structure and changes in various indicators of stand to offer new approaches to forest management. The results of this research can show the conservation effects on yew stands in long-term and short-term conservation periods. It helps provide effective and useful conservation solutions.

Identifying the relationship between conservation of biodiversity and ecosystem processes is one of the main topics in ecological research. Forests are one of the valuable natural resources of the planet, which plays an important role in the ecological balance and the lives of human societies. Diversity of tree species is one of the key parameters for describing forest ecosystems in the management of nature. Modeling and preparing a map of tree diversity is a useful tool for conservation and management of forests. In terms of tree diversity, the Caspian forests are the richest forests in Iran that have undergone severe changes in recent years. One of the most important and most effective ways to learn about tree diversity is the use of satellite imagery. The aim of this study was to determine the capability of GeoEye images in monitoring of tree diversity in circular forest forests in Mazandaran province.

For this purpose, 150 landfills of 30 to 30 meters in length were used for field surveying. Then, the Shannon-Weiner, Simpson and Simpson indexes were calculated for each sample piece. Pre-processing and necessary processing, such as principal component decomposition, making vegetation indices and texture analysis were performed on the images. For modeling, classification and regression tree methods, random forest, different variants of the nearest neighbor and different kernels of backup machine were used. Of the 70% of the teaching samples used for modeling. Then the best bands were selected for modeling. Models were evaluated using 30% of the samples. Then the best models were specified for each part.

The results showed that the indices produced, the infrared band and the resulting bands were identified as the best band for modeling. The RBF kernel has the best result from a backup machine with a 58% explanatory factor and a root mean square error of 46% for modeling the Shannon Wiener Diversity Index among the above models. Also, the method of random forest with the coefficient of explanation of 54 and 57 percent, and the root mean square error margin of about 48 and 14 percent, respectively, for the Simpson and Simpson images have the best results.

The results showed that GeoEye satellite data has a relatively good ability to estimate tree diversity in circular forest forests. The models used by the random forest method for two modes and the RBF kernel were the best-performing vector-path vector technique in one state. Overall, the results showed that these data can be used for management, conservation and monitoring of tree diversity in the northern forests of the country.

Abstract

One of the main concerns of wood industry is the supply of wooden raw material. So it is important to consider the issues that address part of the existing concerns in different ways, such as reducing wood consumption in the production of wooden products. Application of lightweight composite products using polystyrene is considered as a solution to reduce the consumption of raw materials. Important properties considered for these types of products include their behaviors against electricity and acoustic properties. This study aims to evaluate the dielectric and acoustic behaviors of the composite studied herein.

In order to construct test samples, the most optimum treatment was selected from the treatments based on mechanical strength and physical properties to examine the electrical behavior and acoustic properties. To prepare lightweight test samples polystyrene, control samples were made at a densities of 0.7 g/cm3 (C1) and 0.5 g/cm3 (C2). The first density of control sample was chosen to compare the test specimen with a standard composite, and the second density of control sample was selected to compare the test sample with a composite product of similar density without polystyrene granules.

The results of electrical resistance test showed no significant differences between the lightweight test sample and C2 with a density of 0.5 g/cm3 due to their density equivalence. Also, electrical resistance was not significantly different between specimens with a density of 0.5 g/cm3 and heavier specimens with a density of 0.7 g/cm3. The results indicated that the specific gravity of the samples indirectly affected the electric resistance of the samples. At a certain density, the addition of polystyrene granules resulted in improved electrical resistance and acoustic properties of the samples.

The results of the tests showed that decreasing density of the samples resulted in increased electrical resistance and improved sound absorption of the samples. The presence of polystyrene granules in test samples, in addition to acting as a strong insulator, has an effect on the behavior of the samples possibly leading to an increase in their electrical resistance. Polystyrene granules have directly affected the acoustic properties of the samples. The results showed that lightweight boards using granular polystyrene can be used effectively in cases where there is a need for increased electrical resistance and improved sound insulation property, taking into account the allowable mechanical load tolerance by the boards.

Today, the use of cellulosic nanofibers is widely researched for the production of various products, such as paper and paperboard. Cellulose nanofibers are made from pulp produced from various lignocellulosic sources in various methods. The quality of these materials can be evaluated in different ways. Meanwhile, the rheology indices of cellulosic nanofibers are one of the simplest and least costly methods to evaluate the quality of this material. In this paper, specifically, the relationship between indices of rheology of cellulosic nanofibers and their ability to improve paper and board strengths for papermaking are introduced.

In this article, materials were categorized in terms of rheology sciences and cellulose nanofibers were specified among them. Then, important indices of rheology of cellulose nanofibers such as yield point, damping coefficient, storage modulus, loss modulus, and yield strain were introduced by presenting some of the results of measuring the rheological indices of cellulosic nanofibers. In the following, the relationship between rheological indices and strengthening ability of cellulose nanofibers to improve tensile and burst strengths of paper and paperboard production were investigated.

The more storage modulus, as the most sensitive parameter in viscoelastic measurements compared to the loss modulus, the more viscoelastic ability and more elastic tendency. For cellulose nanofibers, if the ratio of the storage modulus is about 4 times greater than the loss modulus in the same concentrations, this indicates that the material is viscoelastic with considerable elasticity. If the amount of damping coefficient for cellulose nanoparticle gel is less than 0.3, this indicates that these gels are highly elastic with components in the nanometer scale and these characteristics indicate the presence of tangled cellulose nanofiber network and as a result, more strengthening feature is available for a variety of applications as strengthening paper and paperboard products. The critical strain on the behavior of the cellulosic nanofiber’s rheology appears almost independent of its dry matter content which implies the sustainability of the viscoelastic properties of these gels. The thick and dilute produced nanofiber gels have an exponential, with power 3, relationship with dry content (n ∝ G∅). The exponential, with power 3, relationship between the modulus and dry matter percentage is one of the criteria for the achievement of a gel of nanoscale cellulosic fibres.

In general, cellulose nanofibers gel is considered as a viscoelastic and thixotropic fluid and when used in paper and paperboard productions, the higher elastomeric index of it creates more strength properties of products. Therefore, in order to predict the achievement of nanosized fibres gel during production, a cheaper evaluation of the cellulosic rheology indices could be used instead of expensive images and even with the comparison of two types of cellulosic nanofibers, their rheological properties predict their performance for reinforcing paper and paperboard.

chitin and chitosan, as the most abundant amino-polysaccharide in nature, have characteristics such as biocompatibility, low toxicity, and biodegradability. These unique specifications have resulted in chitin and chitosan attracting a lot of attention because of the high potential for producing valuable products. Chitosan has many uses in the agricultural industry and wood preservation, such as pesticides and insecticides, as well as in biomedical applications, including the use in the pharmaceutical industry as a drug release, and can also be used as drug carriers. The purpose of this article is to extract highly purified chitosan with high de-acetylation degree from shrimp shells.

In this study, the extraction and characterization of chitosan from the shrimp shell (Litopenaeus vannamei) was investigated. For this purpose, chitosan was extracted by chemical method including mineralization (with 4% HCl concentration), protein degradation (with 4% NaOH concentration), and deacetylation (with 60% NaOH concentration). Also, nano-chitosan was prepared by ionic gelation method. A series of parameters were studied, which included the degree of deacetylation, molecular weight, pH and solubility. Also, FTIR spectroscopy, FESEM scanning electron microscopy, Zeta potential, X-ray diffraction spectroscopy (EDX) and X-ray diffraction (XRD) were used.

The results of FTIR test on chitin and chitosan extracted from shrimp shell showed that the removal of protein and mineral materials was appropriate with the use of hydrochloric acid, sodium hydroxide. The high degree of deacetylation of chitosan in this study (87%) had a significant effect on the proper solubility and low viscosity of chitosan. The solubility of chitosan in acetic acid was 86%. The molecular weight of the chitosan extracted was 110 kDa. With this molecular weight, chitosan can be used well in the pharmaceutical industry. According to chitosan XRD patterns in previous studies, the peaks obtained in XRD patterns in this study confirmed the semi-crystalline structure of chitosan. Due to the change in the level of chitosan seen in FESEM images, it can be due to the purification of chitosan. The FESEM test confirms nano-chitosan with diameter range of 100 to 150 nm.

From the results of this study, it can be concluded that using the chitosan extraction method in this research, highly purified chitosan with high de-acetylation degree can be obtained. With increasing degree of deacetylation, the solubility of chitosan has increased, and this degree of deacetylation has had a significant effect on improving molecular weight (Low molecular weight). As a result of the study of the role of solubility of chitosan in the vicinity of acetic acid, it becomes obvious that the solubility of the chitosan and the size of the nano-chitosan particles depend on the solution pH. The produced chitosan can be used in wide variety of application mainly in pharmaceutical industry.

Biological wastes such as lignocellulosic materials are on high attention for the purification of contaminated water due to their special properties, such as renewability, biodegradability, and low costs. However, despite its many benefits, disadvantages such as hydrophilic structure, low adsorption capacity, and the lack of flotation have limited the vast application of these natural materials. Therefore, the necessity of producing novel adsorbents with significant capacity such as aerogels has been concerned. Cellulose aerogels have good performance due to their special properties such as low density, high specific surface area and high porosity. In this paper, the effectiveness of cellulose aerogel adsorbents for removing oil and organic solvents from water has been studied. After the extraction of long cellulose micro-nano fibrils from rice straw by chemical and mechanical processes, cellulosic aerogels are fabricated and their efficacy for water pollution remediation was evaluated. The high porous structure and very low density of these cellulosic aerogels are highly desired for the adsorption of organic solvents and oils.

In this research, the rice straw was washed, dried, milled and completely passed through the mesh. The straw wax was extracted using a mixture of toluene/ethanol solution. In order to separate lignin, de-waxed rice straw was combined with a desired amount of sodium chlorite solution in an acidic environment. After de-lignification, the dry specimen was combined with potassium hydroxide solution until the hemicellulose and silica were totally removed from the fibers and pure cellulose fibers remained. After extraction of cellulose, suspension of cellulosic fibers was homogenized using high speed homogenization and the suspension was then treated with high-intensity ultrasonic apparatus with a frequency of 20 kHz. In order to produce aerogels, the suspensions of cellulose micro-nanofibres containing different amount of crosslinking agent were prepared in various concentrations. The suspensions were dried in a freeze-dryer. Finally, using a chemical vapor deposition method (CVD) with trimethoxysilane, the surface of cellulose aerogel became hydrophobic. The water adsorption capacity of cellulose aerogels in the presence of various concentrations of the crosslinker was determined to optimize the concentration of the crosslinker. Furthermore, the density and porosity of cellulosic aerogels were investigated at various cellulose contents. The structure and morphology of aerogels were evaluated using a scanning electron microscope. The application of these cellulosic aerogel in elimination of water pollution was also studied.

In the pre-freezing process, the use of liquid nitrogen resulted in the rapid freezing of cellulose suspension which produced highly porous structure of aerogels. Adding a crosslinking agent improved the wet strength and stability of the cellulose aerogel structure. As the concentration of cellulose fibers increased, the density of cellulose aerogel increased and simultaneously the porosity decreased. The scanning electron microscopic images of cross-sectional area of aerogels represented a porous structure with a pore size of one to several hundred micrometers, distributed throughout isotropic structure. The results of the water contact angle test revealed a mean value of 151.7 ° for the coated sample, indicating the super-hydrophobicity of the cellulose aerogel. The hydrophobic cellulose aerogel had a highly desirable adsorption capability in the range of 130-69 g.g-1 for different types of oil (pump oil, crude oil, paraffin, diesel oil) and organic solvents (toluene, acetone, dimethylformamide, and chloroform).

Generally, very low density and high porous hydrophobic cellulose aerogel obtained from rice straw through series of chemical and mechanical treatment, had substantial adsorption capacity for organic solvents and oils.