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Measuring the vibration of a brush cutter in different operation modes
95-98.Views:207The vibration load of a hand-held machine depends on many factors not defined in the ISO 5349:2001 standard about the measurements and evaluation of human exposure to hand-transmitted vibration. In this study, the effect of different operation modes on the vibration emission of a brush cutter was investigated. The frequency weighted r.m.s. acceleration was measured at the front (left) and rear (right) handle in three orthogonal directions according to ISO 5349 (2001). Two set of measurements were performed with three subjects for
idling and cutting operations. In addition, the acceleration was measured with two holding positions, i.e. the cutting head is tilted by 45˚ to the left and tilted by 45˚ to the right. The standard vibration evaluation method, with the cutting head parallels to the ground, significantly under-estimated the vibration emission of the tilted tool to the left and right. The results suggest that the use of different holding positions would improve the reliability of the standard method of assessing the vibration of hand-held tools. -
Bioactive phenols in leaves of Forsythia species
57-59.Views:240Nowadays a number of lignans (arctigenin, matairesinol, pinoresinol and phillygenin) have come to the fore in research due to their various biological activities. In this paper the accumulation of these constituents in leaf extracts of Forsythia plants (F. intermedia, F. ovata 'Robusta’ and `Tetragold', F. suspensa, F. viridissima) was quantified using a new isolation method, supercritical CO2 fluid extraction. The total phenolic and flavonoid contents, the antioxidant capacity and the aglycone lignan profile were determined in leaf extracts of Forsythia species. Within the phenols, the flavonoids were only present in small quantities, but the amount of aglycone lignans was extremely high. F. ovata `Robusta' had the highest total lignan content (103.8 mg/g) of all the Forsythia species. The main lignan in this species is arctigenin, which normally makes up about 60% of the total lignan content, but in the case of F. ovata `Robusta' this value was 96.1%. Since this arctigenin content is outstanding compared to that of other Forsythia species, it could be promising to develop a fermentation technology for the production of this natural compound.
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The effect of wear of petrol engine power brush cutters on their vibration exposure
37-44.Views:207The matter of noise and vibration exposure has an accentuated emphasis in the environmental protection policy of the European Union. In practice, the focus is on the evaluation of noise -strain. The evaluation on human beings' vibration-strain is in focus in recent years. At the Technical Department in Corvinus University of Budapest Faculty of Horticultural Sciences we evaluate in PhD training form the possible ways of alleviation and revealance of noise and vibration-strain in gardening devices and machineries. According to the latest development in gardening culture, small gardening machines are more and more widespread. There is a law in Hungary for the compulsory grass-cutting, especially on 'ragweed' (Ambrosia elatior). Along highways, public territories, parks workmen at least six months are in charge to terminate these weed-crops meanwhile they are endangered by serious harmful effects. The operators of hand-held power tools are exposed comprehensive levels of hand-arm vibration at the tool-hand interface. Many studies indicate that extended exposure to mechanical vibration can induce degeneration of the vascular and sensioneural systems in the hand called hand-arm vibration syndrome (HAVS). The precise mechanism for the initiation and development of HAVS is unclear to date. Measurement and risk assessment of hand-transmitted vibration is mostly based on the guidelines and dose-response relationship provided in the ISO-5349 standard. These guidelines suggest that the magnitude, frequency, direction and duration of vibration exposure are the most important variables for the risk assessment of hand-arm vibration. This current study is focusing on brush cutters owned by one of the biggest caretaker company. These machines have similar brand and age but different in usage time. We inquired seven brush cutters through two years. The manufacturer repaid the vibration level of the new machines, but they doesn't examine, whether extent of the vibration emission is changing for the proper use. We wanted to know that are there any differences between the values of vibration specification after certain time of usage. Is it possible to monitor the alternate movements on graphs according to the vibration sciences? By Ill octave band frequency and FFT analysis we can point at that these brush cutters can show differences in critical frequencies. These biases can influence the hand-arm system and its vibration-strain burdening.
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Determination of auxine content of soft wood cutted `Marianna GF8/1' (Prunus cerasifera x P. munsoniana) by High Performance Liquid Chromatography during rooting period
67-70.Views:138The content of different auxins of soft-wood cutted plum rootstock 'Marianna GF8/1' (Prunus cerasifera x P. munsoniana) was determined during the rooting period. The level of auxin-concentration (exogenous and endogenous) of basic and intemodal part of cuttings was determined by WATERS HPLC equipment every 7 days during rooting period. The lengths soft wood cuttings were app. 30 cm long. The basal part of shoots were treated with 2000 pg/g concentrated indole-butiryc acid in talcum powder. After treatment the cuttings were placed in propagation green-house under intermittent mist. The plant hormones were extracted by methanol the solution was cleaned by paper-filter, and further cleaned by centrifuge. The effluent was examined by reversed phase High Performance Liquid Chromatography, with WATERS 2487 dual detector at 220 am on Symmetry C18 4,6x 150 column. Recovery and reproducibility assessment indicates good accuracy and acceptable relative standard deviation (RSD) 5%. Linear responses (r20.997) for calibration curve was obtained with IAA, IPA and IBA standard in range, with a limit of quantification of 0.15 g•m1-1. The concentration of IAA, IPA and IBA in the basal part of cuttings were measured, during the rooting period. We proved the external IBA was taken up by the plants. In the plants were found the IBA, and the IAA concentration of IBA treated cuttings was higher, than the untreated one.
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Eicosapentaenoic acid production by Phaeodactylum tricornutum under different culture condition
133-136.Views:141Phaeodactylum tricornutum UTEX 640 strain of microalgae was screened under different culture conditions for their capacity to produce eicosapentaenoic acid (EPA) the most abundant polyunsaturated fatty acid (PUFA). In our experiments, the effect of sodium chlorid, nitrogen source, phosphate, initial pH, as well as the CO2 content of the medium on production of the eicosapentaenoic acid (EPA) by P. tricornutum were investigated. The EPA content of biomass was enhanced by the low pH of the medium, with increased concentrations of B17 vitamin and nitrate, and also with decreasing concentrations of sodium chlorid. The EPA is most likely associated with polar (membran) lipids and the role of EPA appears to be involved with membran permeability in microalge. The synthesis of phospholipids, enhances the EPA content of the cells, as expected. The maximum EPA yields were observed under optimum culture condition 43 — 48 mg/g of dry cell weight.
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Interaction impact of drought stress, nutrient-deficient water, and seed-borne pathogen (Alternaria alternata) on germination and vigor of two tomato varietiesination and vigor of two tomato varieties
48-53.Views:88Tomato (Solanum lycopersicum) is considered one of the leading vegetable plants in the world. This study evaluated the germination and vigor capabilities of ‘Marmande’ and ‘Kecskeméti Jubileum’ varieties under different conditions, including drought stress, nutrient-deficient water, and the effect of seed-borne disease caused by Alternaria alternata when prime and non-prime with salicylic acid. The experiment was conducted in the laboratory in 2023 at Agricultural and Food Sciences and Environmental Management Faculty of University of Debrecen. Results indicated that the ‘Kecskeméti Jubileum’ variety exhibited a superior strength to ‘Marmande’ in the seedling’s dry weight, seedling growth rate, and vigor index under nutrient-deficient water. Nevertheless, when applying levels of drought, the ‘Marmande’ variety had a higher viability rate of 62.5% in comparison with another variety, and the germination rate of the two tomato varieties is at 85.5% in 5% concentration but decreased progressively when exposed to a higher drought concentration of 10%. When using 3 ml of salicylic acid during germination stages, the seedling vigor index of ‘Marmande’ shows a greater index at 165 compared to ‘Kecskeméti Jubileum’, just 108 under the infection of Alternaria alternata. The results of the examination of drought stress, and the effect of Alternaria alternata, one cause of seed-borne pathogens, showed that the percentage germination and vigor ability of the ‘Marmande’ variety performed better than ‘Kecskeméti Jubileum’ under the same conditions.
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Evaluation of lifespan values of six tree taxa in city streets
25-27.Views:329The aim of this study was to evaluate lifespan values of trees in tree-row system in the streets of Debrecen in two years (2009 and 2017). Six selected taxa (Pyrus calleryana, Acer tataricum, Sorbus intermedia, Magnolia kobus, Acer platanoides and Crataegus x lavalleei) were estimated for the following lifespan parameters: i) trunk diameter (cm), ii) tree crown size (m), iii) trunk status (in 0-5 grades), iv) tree crown status (in 0-5 grades), and v) estimated tree viability (in 0-5 grades). Our results showed that the largest were achieved for Pyrus calleryana and the lowest for Acer tataricum. The largest tree crown diameters were achieved for Acer platanoides and the lowest Magnolia kobus. The best trunk statuses by 2017 were achieved for Pyrus calleryana and the worst Crataegus x lavalleei. The best tree crown statuses by 2017 were achieved for Pyrus calleryana and the worst for Acer tataricum. The best estimated tree viability status was achieved for two taxa (Pyrus calleryana and Acer platanoides). Overall tree values were 2.73 times higher in 2017 compared to 2009. In summary, this study demonstrated the role of appropriate choice of tree taxa for a tree-row system under city street conditions.