Abstract:The article provides information about the anatomical structure of the vegetative and generative organs grown in Tashkent conditions, and reveals the structural features: a mesomorphic leaf, a dorsi-central mesophyll type characteristic of dicotyledonous plants; stem beam type. A comparative analysis of the anatomical structure showed that the seed coat has a general plan of the structure with other members of the family Asteraceae.
“…Both the bark and the xylem separated during the stages of retting. This part of anatomy is similar to other anatomical studies done by some biological searchers for same plant 25,26 and other searchers with different plants. 27,28 Figure 3.Transverse sections from the stem of Silybum marianum Plant.…”
The present investigation aimed to understand the physicochemical properties of the new cellulosic fiber extracted from the bark of Silybum marianum (SM), in view of using it as a potential reinforcement for polymer composites. The morphological and anatomy, physical, thermal and mechanical properties of fibers were firstly discussed in this paper. The Silybum marianum fibers (SMF) were characterized by scanning electron microscopy, Fourier transform infrared, thermogravimetric analysis (TGA), optical microscope, X-ray diffraction (XRD), and single fiber tensile test. The average Young’s modulus and the breaking stress data presented by the fibers are 15.97 GPa and 201.16 MPa, respectively. XRD reveals the presence of cellulose with a crystallinity index of 45%. Thermal stability (250°C) and maximum degradation temperature (357.72°C) of the SMF are established by the thermogravimetric analysis. An analysis of the mechanical properties was carried out on a population of 35 samples using Weibull statistics with two and three parameters.
“…Both the bark and the xylem separated during the stages of retting. This part of anatomy is similar to other anatomical studies done by some biological searchers for same plant 25,26 and other searchers with different plants. 27,28 Figure 3.Transverse sections from the stem of Silybum marianum Plant.…”
The present investigation aimed to understand the physicochemical properties of the new cellulosic fiber extracted from the bark of Silybum marianum (SM), in view of using it as a potential reinforcement for polymer composites. The morphological and anatomy, physical, thermal and mechanical properties of fibers were firstly discussed in this paper. The Silybum marianum fibers (SMF) were characterized by scanning electron microscopy, Fourier transform infrared, thermogravimetric analysis (TGA), optical microscope, X-ray diffraction (XRD), and single fiber tensile test. The average Young’s modulus and the breaking stress data presented by the fibers are 15.97 GPa and 201.16 MPa, respectively. XRD reveals the presence of cellulose with a crystallinity index of 45%. Thermal stability (250°C) and maximum degradation temperature (357.72°C) of the SMF are established by the thermogravimetric analysis. An analysis of the mechanical properties was carried out on a population of 35 samples using Weibull statistics with two and three parameters.
“…the phloem average thickness of species N. syriaca 25.56 μm. The midrib form in species S. marianum convex, dome-shaped, these results are consistent with the study of Nigmatullaev (2019) indicated that the Midrib of the species S. marianum contained a bundle of collenchyma supporting tissues in a dome-shaped. the average thickness of collenchyma tissue 74.13 μm.…”
“…syriaca and S. marianum under study are demonstrated table2and figure1. The form of stem cross section of species N. syriaca and S. marianum were cylindrical ribbed or beam like, this is approvement with(Nigmatullaev et al, 2019). The epidermis cells in species N. syriaca consist of 1-2 rows, the outer wall enveloped by thin or thick a cuticle layer, the epidermis cell form of species N. syriaca roundish-oval with average thickness 9.76 μm, followed by 4-6 layers of collenchyma cells next, the cortex layer, composed of 3-7 rows of parenchymal cells with average thickness 152.72 μm, the vascular bundle surround by sclerenchyma cells composed bundle sheath cells, the vascular bundles arranged in two rings and the xylem tissue contain 4-7 rows.…”
This research was carried out to study the sources of work related Stress risk at the construction sector of Afghanistan. Stress risk is major problem not only in Afghanistan but also all over the world. It is important to ensure that workers can perform best, considering the highly competitive demands and competition of the construction industry. The objectives of this research are to study the sources of work related stress risk at the construction sector of Afghanistan. The methodology of this study includes data collection, and data analysis. Data was collected using questionnaire survey in Afghanistan through email from the construction industry professional such as project manager, site supervisor, project engineer, quantity surveyor, and architect. The data was analyzed using frequency analysis, the average index. To visualize the result, tables, figures like bar, and pie charts were used to clarify the results. The research revealed that the physical environment, the job itself, and the organization is the key factor for the source stress risk at construction industry of Afghanistan. Based on the analysis of likelihood and severity from eighteen fifteen were main sources were in the very high and high stress risk category for the factors such as workload, work pattern, and work environment.
The article presents the results of the morpho-anatomical structure of the assimilation organs of the species Salsola leptoclada Gand, which is widespread in the Kyzylkum desert region of Uzbekistan, and reveals the structural, diagnostic and adaptive features. In the assimilation organs, Kranz type of mesophyll was found: in the cotyledons of the Kranz-spherical (Atriplicoid) type, and in the leaf-mesophylls of the Kranz-centric (Salsoloid) and Kranz-ventrodorsal type. These revealed diagnostic features of the assimilating organs of this species in arid conditions noted C4-type photosynthesis. Based on the comparative biometric analysis of quantitative indices of the anatomical features of the assimilating organs, xero-halomorphic features predominate. Halomorphic features are in the cotyledons-thin outer walls of the epidermal cells; few stomata of the anomocytic and paracytic type; few rows of spongy cells (3 -4 rows); few vascular bundles of the collateral type and xylem, in the leaf-large and thin outer walls of the epidermal cells; succulence of the leaf mesophyll, the presence of aquiferous cells; large palisade, keratin and aquiferous cells. Xeromorphic features in the cotyledons-small and numerous epidermal cells and hemiparacytic type stomata also deep immersion; small palisade cells and a high palisade index, small spongy, hypodermal and keratin cells; small diameter of the xylem in vascular bundles; in the leaf numerous epidermal cells and stomata also deeply immersed; presence and numerous multicellular nodular, dentate trichomes; multi-row water-bearing cells; high palisade index; small and numerous xylem; numerous peripheral vascular bundles of the collateral type. These identified specific diagnostic features showing adaptation to arid conditions can also serve in the identification of plant materials.
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