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Wyświetlanie 1-15 z 465
Tytuł:
Numerical Analysis Of Mixing Under Low And High Frequency Pulsations At Serpentine Micromixers
Autorzy:
Malecha, Z. M.
Malecha, K.
Powiązania:
https://bibliotekanauki.pl/articles/185164.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
aktywne mieszanie
symulacja numeryczna
technologia LTCC
serpentine micromixer
active mixing
numerical simulations
LTCC technology
Opis:
The numerical investigation of the mixing process in complex geometry micromixers, as a function of various inlet conditions and various micromixer vibrations, was performed. The examined devices were two-dimensional (2D) and three-dimensional (3D) types of serpentine micromixers with two inlets. Entering fluids were perturbed with a wide range of the frequency (0 – 50 Hz) of pulsations. Additionally, mixing fluids also entered in the same or opposite phase of pulsations. The performed numerical calculations were 3D to capture the proximity of all the walls, which has a substantial influence on microchannel flow. The geometry of the 3D type serpentine micromixer corresponded to the physically existing device, characterised by excellent mixing properties but also a challenging production process (Malecha et al., 2009). It was shown that low-frequency perturbations could improve the average mixing efficiency of the 2D micromixer by only about 2% and additionally led to a disadvantageously non-uniform mixture quality in time. It was also shown that high-frequency mixing could level these fluctuations and more significantly improve the mixing quality. In the second part of the paper a faster and simplified method of evaluation of mixing quality was introduced. This method was based on calculating the length of the contact interface between mixing fluids. It was used to evaluate the 2D type serpentine micromixer performance under various types of vibrations and under a wide range of vibration frequencies.
Źródło:
Chemical and Process Engineering; 2014, 35, 3; 369-385
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influential factors affecting materials management in construction projects
Autorzy:
Jusoh, Z. M.
Kasim, N.
Powiązania:
https://bibliotekanauki.pl/articles/406714.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
construction projects
project performance
materials management
influential factors
Opis:
Construction projects are more often than not plagued by poor performances such as delays, cost overrun, low productivity, construction wastes and compromised quality. Amongst the critical contributory factors of poor project performances, is the ineffectiveness of materials management occurring in the construction sites. Indeed, materials management is a very important component for construction projects. However, there are only limited numbers of research available regarding this topic. Thus, this research focuses its study on materials management, specifically in identifying the influential factors that affect materials management in the construction project activities. Literatures from books, journal articles and conference papers related to poor project performances and materials management have been reviewed. Consequently, this study sorted the salient influential factors and categorized them based on their specific group. Out of 47 factors identified, they are classified into 8 groups. They are (1) site condition; (2) planning and handling on site; (3) management; (4) materials; (5) supplier and manufacturer default; (6) transportation; (7) contractual; and (8) governmental interferences. In conclusion, this study contends that by identifying the influential factors affecting materials management, it will help construction players to avoid the occurrence of those factors and will minimize the negative impacts on the overall performance of construction projects. Hence, the handling-over of project will be according to schedule and not delayed by materials mismanagement.
Źródło:
Management and Production Engineering Review; 2017, 8, 4; 82-90
2080-8208
2082-1344
Pojawia się w:
Management and Production Engineering Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of correlation coefficient between geoid-to-quasigeoid separation calculated by the satellite data in Sjöberg’s equation and GPS/Levelling method
Autorzy:
Eshaghzadeh, A.
Kalantari, R. A.
Hekmat, Z. M.
Powiązania:
https://bibliotekanauki.pl/articles/145523.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
geoida
GPS
poziomowanie
geoid
GPS levelling
ICGEM
quasigeoid
Sjöberg’s equation
Opis:
In this paper, two techniques for calculating the geoid-to-quasigeoid separation are employed. One of them is GPS/Levelling customary method as a criterion where the geoid undulation and height anomaly are computed by subtracting the ellipsoid height attained via GPS from the orthometric height and normal height, respectively. Another approach is Sjöberg’s equation. We have used of the ICGEM website for definition of the variables of the Sjöberg’s equation, as the applied reference model is the EGM2008 global geopotential model and WGS84 reference ellipsoid. The investigations are performed over the stations of the GPS/Leveling network related to three selected areas in desert, mountain and flatland namely the Lout, Zagros and Khuzestan in Iran and afterward the correlation coefficient between the geoid-to-quasigeoid separation calculated using the satellite data in Sjöberg’s equation and GPS/Levelling method is estimated. The results indicate a straight correlation between the estimated separations from the two methods as its value for the Lout is 0.754, for the Zagros is 0.497 and for the Khuzestan is 0.659. consequently, using the satellite data in Sjöberg’s equation for the regions where there are not the GPS/Levelling and land gravity data, specially for the even areas, yield a satisfactory response of the geoidto-quasigeoid separation.
Źródło:
Geodesy and Cartography; 2018, 67, 2; 179-192
2080-6736
2300-2581
Pojawia się w:
Geodesy and Cartography
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metrological Aspects Of Evaluation of Glass Types Used in Photovoltaic Modules in Laboratory Scale
Autorzy:
Starowicz, Z. M.
Drabczyk, K.
Gawlińska, K.
Zięba, P.
Powiązania:
https://bibliotekanauki.pl/articles/220981.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
photovoltaics
silicon solar cells
module glass cover
lamination process
Opis:
The front glass cover is the crucial part of commercially available silicon solar modules as it provides mechanical protection and environmental isolation. However, from a utility point of view the most important thing is how the glass cover influences the power generation of a photovoltaic (PV) module. Optical matching of the whole structure determines the number of photons absorbed by the solar cells and hence the produced photocurrent. In this study five types of PV glass were optically measured and characterized to find out useful information on transmittance and its character. Then, the results were compared with the electrical parameters of solar mini-modules employing each type of glass. Additionally, the work aimed to providing a low-cost measuring procedure to determine the influence of front glass on photovoltaic performance in small, laboratory scale preserving the Standard Test Conditions. An important aspect was an analysis of different types of glass texture. To confirm properness and adequacy of the analysis, the uncer- tainty aspect was discussed as well.
Źródło:
Metrology and Measurement Systems; 2018, 25, 1; 203-211
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Plant extract control of the fungi associated with different Egyptian wheat cultivars grains
Autorzy:
Baka, Z.A.M.
Powiązania:
https://bibliotekanauki.pl/articles/66361.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
Grain samples of 14 Egyptian wheat cultivars were tested for seed-borne fungi. The deep freezing method was used. Five seed-borne fungi viz., Aspergillus flavus, A. niger, Curvularia lunata, Fusarium moniliforme and Penicillium chrysogenum were isolated from the wheat cultivars viz., Bani Suef 4, Bani Suef 5, Gemmiza 7, Gemmiza 9, Gemmiza 10, Giza 168, Misr 1, Misr 2, Sakha 93, Sakha 94, Shandaweel 1, Sids 1, Sids 2 and Sids 3. A. flavus, A. niger and F. moniliforme were the most prevalent fungal species. Their incidence ranged from 21.0-53.5%, 16.0-37.5%, and 12.0-31.0%, respectively. The antifungal potential of water extracts from aerial parts of five wild medicinal plants (Asclepias sinaica, Farsetia aegyptia, Hypericum sinaicum, Phagnalon sinaicum, and Salvia aegyptiaca) were collected from the Sinai Peninsula, Egypt. The antifungal potential of water extracts from the aerial parts of these five plants were tested in the laboratory against the dominant fungi isolated from the wheat cultivars. All the aqueous plant extracts significantly (p ≤ 0.05) reduced the incidence of the tested seed-borne fungi. But the extract of Asclepias sinaica exhibited the most antifungal activity on tested fungi at all concentrations used when compared with other plant extracts. Maximum infested grain germination was observed in Giza 168 and minimum in Bani Suef 5. Treating grains with plant extract of A. sinaica (10%) enhanced the percentage of grain germination of all cultivars in both laboratory and pot experiments. Maximum root and shoot length of seedlings was recorded in Bani Suef 4 during fungal infestation or treatment by plant extract. For one hour before sowing or storage, the aqueous extract of A. sinaica can be used to treat wheat grains, to reduce the fungal incidence. Aqueous extracts of the aerial parts of selected medicinal plants, particularly A. sinaica, are promising for protecting Egyptian wheat grain cultivars against major seed-borne fungi. The aqueous extracts are expected to improve crops.
Źródło:
Journal of Plant Protection Research; 2014, 54, 3
1427-4345
Pojawia się w:
Journal of Plant Protection Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Age-related changes in mRNA expression of selected surface receptors in lymphocytes of dairy calves
Autorzy:
Flaga, J.
Korytkowski, Ł.
Górka, P.
Kowalski, Z.M.
Powiązania:
https://bibliotekanauki.pl/articles/2087753.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
immune system development
clusters of differentiation
marker
lymphocyte maturation
Źródło:
Polish Journal of Veterinary Sciences; 2018, 21, 1; 213-216
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Production of Biogas Using Maize Silage Supplemented with Residual Glycerine from Biodiesel Manufacturing
Wytwarzanie biogazu podczas wspólnej fermentacji kiszonki kukurydzy zwyczajnej i frakcji glicerynowej z produkcji biodiesla
Autorzy:
Pokój, T.
Gusiatin, Z. M.
Bułkowska, K.
Dubis, B.
Powiązania:
https://bibliotekanauki.pl/articles/204753.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
anaerobic digestion
residual glycerine
energy crops
maize silage
glycerol osmotic pressure
biogaz
fermentacja beztlenowa
frakcja glicerynowa
rośliny energetyczne
kiszonka z kukurydzy
ciśnienie osmotyczne
Opis:
The aim of this study was to investigate the influence of residual glycerine (5 and 10% w/w) from the biodiesel industry, used as a co-substrate, on biogas production from maize silage. The experiments were conducted in a laboratory-scale, single-stage anaerobic digester at 39ºC and hydraulic retention time (HRT) of 60 d. Addition of 5% residual glycerine caused organic load rate (OLR) to increase to 1.82 compared with 1.31 g organic dry matter (ODM) L-1d-1 for maize silage alone. The specific biogas production rate and biogas yield were 1.34 L L-1d-1 and 0.71 L g ODM-1 respectively, i.e. 86% and 30% higher than for maize alone. Increasing the residual glycerine content to 10% increased OLR (2.01 g ODM L-1d-1), but clearly decreased the specific biogas production rate and biogas yield to 0.50 L L-1d-1 and 0.13 L g ODM-1 respectively. This suggested that 10% glycerine content inhibited methanogenic bacteria and organics conversion into biogas. As a result, there was accumulation of propionic and valeric acids throughout the experiment.
W pracy badano wpływ frakcji glicerynowej w stężeniu 5 i 10% wag. na produkcję biogazu z kiszonki kukurydzy zwyczajnej. Doświadczenie prowadzono w skali laboratoryjnej, w układzie jednostopniowym. Hydrauliczny czas zatrzymania (HRT) i temperatura fermentacji wynosiły odpowiednio 60d i 39ºC. Udział frakcji glicerynowej substracie w stężeniu 5% wag. spowodował wzrost obciążenia ładunkiem organicznym (OLR) do 1,82 g s.m.o./dm3·d w porównaniu do OLR podczas fermentacji samej kiszonki (1,31 g s.m.o./dm3·d). Jednostkowa szybkość produkcji biogazu oraz współczynnik wydajności biogazu wyniosły odpowiednio 1,34 dm3/dm3·d oraz 0,71 dm3/g s.m.o. i były o 86% oraz 30% wyższe w porównaniu do wartości uzyskanych dla samej kiszonki. Gdy stężenie frakcji glicerynowej w substracie wzrosło do 10% wag. (OLR = 2,01 g s.m.o./dm3·d) jednostkowa szybkość produkcji biogazu oraz współczynnik wydajności biogazu wyraźnie zmalały do 0,50 dm3/dm3·d i 0,13 dm3/g s.m.o, co oznacza, że w stężeniu 10% wag. frakcja glicerynowa miała inhibicyjny wpływ na wzrost metanogenów i konwersję substancji organicznych do biogazu. W rezultacie następowała kumulacja kwasów propionowego i walerianowego w wodzie osadowej.
Źródło:
Archives of Environmental Protection; 2014, 40, 4; 17-29
2083-4772
2083-4810
Pojawia się w:
Archives of Environmental Protection
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Three dimensional modeling and geometric properties of oil plant equipment from terrestrial laser scanner observations
Autorzy:
Elgndy, A. I.
Zeidan, Z. M.
Beshr, A. A.
Powiązania:
https://bibliotekanauki.pl/articles/145342.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
fabryka oleju
skaner laserowy
chmura punktów
modelowanie 3D
modernizacja
oil plant
terrestrial laser scanner
point cloud
3D modeling
revamping
Opis:
Terrestrial laser scanner (TLS) is a new class of survey instruments to capture spatial data developed rapidly. A perfect facility in the oil industry does not exist. As facilities age, oil and gas companies often need to revamp their plants to make sure the facilities still meet their specifications. Due to the complexity of an oil plant site, there are difficulties in revamping, having all dimensions and geometric properties, getting through narrow spaces between pipes and having the description label of each object within a facility site. So it is needed to develop an accurate observations technique to overcome these difficulties. TLS could be an unconventional solution as it accurately measures the coordinates identifying the position of each object within the oil plant and provide highly detailed 3D models. This paper investigates creating 3D model for Ras Gharib oil plant in Egypt and determining the geometric properties of oil plant equipment (tank, vessels, pipes . . . etc.) using TLS observations and modeling by CADWORX program. The modeling involves an analysis of several scans of the oil plant. All the processes to convert the observed points cloud into a 3D model are described. The geometric properties for tanks, vessels and pipes (radius, center coordinates, height and consequently oil volume) are also calculated and presented. The results provide a significant improvement in observing and modeling of an oil plant and prove that the TLS is the most effective choice for generating a representative 3D model required for oil plant revamping.
Źródło:
Geodesy and Cartography; 2018, 67, 2; 193-206
2080-6736
2300-2581
Pojawia się w:
Geodesy and Cartography
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure and Properties of Cu-Nb Wire Composites
Mikrostruktura i własności drutów kompozytowych Cu-Nb
Autorzy:
Głuchowski, W. J.
Rdzawski, Z.M.
Stobrawa, J. P.
Marszowski, K. J.
Powiązania:
https://bibliotekanauki.pl/articles/351916.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
fibrous composite
copper alloy
mechanical properties
electrical conductivity
microstructure
kompozyty włókniste
stop miedzi
właściwości mechaniczne
przewodnictwo elektryczne
mikrostruktura
Opis:
Nowadays, there is much activity all over the world in development of Cu-Nb composites for their potential use as conductors in high field magnets. This study was aimed at investigation of microstructure, mechanical and electrical properties of Cu-Nb composite wires. The investigated materials have been processed by vacuum furnace melting and casting, and then hot forging and cold drawing. Initial results of research into Cu-Nb composite material obtained using repeated iterative drawing of niobium wires compacted into copper tube, have been also presented in this article. The ultimate tensile strength versus cold deformation degree has been presented. These changes have been discussed in relation to microstructure evolution. It was assumed that repeated drawing of compacted wires is a promising method for fibrous composite production (more than 823,000 Nb fibres of nanometric diameter) characterized by high mechanical properties and electrical conductivity. Original SPD technique applied for Cu-Nb composite deformation result in initial microstructure refinement and improves effectiveness of wire production process.
Aktualnie obserwuje się na świecie intensywny rozwój kompozytów Cu-Nb stosowanych jako przewody nawojowe generatorów silnych pól magnetycznych. Badania miały na celu określenie mikrostruktury oraz właściwości mechanicznych i elektrycznych drutów kompozytowych Cu-Nb. Badane materiały wytworzono przez zastosowanie topienia i odlewania w piecu próżniowym, a następnie kucia na gorąco i ciągnienia. Zaprezentowano także wstępne wyniki badań wytwarzania kompozytu Cu-Nb na drodze iteracyjnego ciągnienia pakietu drutów niobowych w rurze miedzianej. Pokazano wyniki badań wytrzymałości na rozciąganie w zależności od stopnia odkształcenia, w powiązaniu ze zmianami mikrostruktury. Stwierdzono, że wielokrotne ciągnienie pakietu drutów jest obiecująca metoda wytwarzania kompozytów włóknistych (ponad 823000 włókien Nb o przekroju nanometrycznym) o wysokich właściwościach mechanicznych i konduktywności elektrycznej.
Źródło:
Archives of Metallurgy and Materials; 2014, 59, 1; 35-40
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Automatic Laser Interferometer And Vision Measurement System For Stripe Rod Calibration
Autorzy:
Zhao, M.
Huang, Q.-H.
Zhu, L.-J.
Qiu, Z.-M.
Powiązania:
https://bibliotekanauki.pl/articles/221047.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
stripe edge
automatic control
laser interferometer
vision measurement
Opis:
In order to calibrate the stripe precision of a leveling rod, an automatic laser interferometer and a vision measurement system were designed by Xi’an University of Technology in China. The rod was driven by a closed-loop control and the data were collected at the stop state to ensure precision. The laser interferometer provided not only the long distance data but also a position feedback signal in the automatic control loop. CCD camera and a vision measurement method were used to inspect the stripe edge position and defect. Apixel-equivalent self-calibration method was designed to improve precision. ROI (regions of interest) method and an outline tracing method were designed to quickly extract multiple stripe edges. A combination of the image data with the interferometer data reduces control difficulty and ensures the measurement accuracy. The vision measurement method reached sub-pixel precision and the defective edges were reported. The system can automatically calibrate a stripe leveling rod with a high degree of efficiency and precision.
Źródło:
Metrology and Measurement Systems; 2015, 22, 4; 491-502
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ADM1-based modeling of anaerobic codigestion of maize silage and cattle manure : calibration of parameters and model verification. Part 2
Modelowanie kofermentacji kiszonki kukurydzy i obornika bydlęcego za pomocą ADM1 : kalibracja i weryfikacja modelu. Część. 2
Autorzy:
Bułkowska, K.
Białobrzewski, I.
Gusiatin, Z. M.
Klimiuk, E.
Pokój, T.
Powiązania:
https://bibliotekanauki.pl/articles/205005.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cattle manure
maize silage
anaerobic digestion
ADM1 modeling
obornik bydlęcy
kiszonka z kukurydzy
fermentacja beztlenowa
modelowanie ADM1
Opis:
The aim of this study was to implement ADM1xp model to simulate behavior of anaerobic co-digestion of maize silage and cattle manure. The accuracy of ADM1xp has been assessed against experimental data of anaerobic digestion, performed at OLR = 2.1 gVS dm-3·d-1 and HRT = 45d. Due to the high number of parameters in ADM1xp, it was necessary to develop a customized procedure limiting the range of parameters to be estimated. The best fitting of experimental to simulated data was obtained after verification of 9 among 105 stoichiometric and kinetic parameters. The values of objective function (Jc) ranged between 0.003 (for valerate) and 211 (for biogas production).
Celem pracy było wykorzystanie modelu ADM1xp do symulacji procesu kofermentacji kiszonki kukurydzy i obornika bydlęcego. Przydatność modelu oceniano wykorzystując dane z eksperymentu w skali laboratoryjnej. Badania prowadzono przy obciążeniu komory ładunkiem organicznym OLR = 2,1 gVS dm-3·d-1 oraz hydraulicznym czasie zatrzymania wsadu w fermentorze, HRT = 45d. Z powodu dużej liczby parametrów w modelu ADM1xp, zastosowano procedurę, która umożliwia zmniejszenie liczby weryfikowanych parametrów podczas kalibracji. Najlepsze dopasowanie danych eksperymentalnych do modelowych uzyskano po weryfikacji 9 spośród 105 stechiometrycznych i kinetycznych parametrów. Wartości współczynnika dopasowania (Jc) zmieniały się w zakresie od 0,003 (kwas walerianowy) do 211 (produkcja biogazu).
Źródło:
Archives of Environmental Protection; 2015, 41, 3; 20-27
2083-4772
2083-4810
Pojawia się w:
Archives of Environmental Protection
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ADM1-based modeling of anaerobic codigestion of maize silage and cattle manure : a feedstock characterisation for model implementation. Part 1
Modelowanie kofermentacji kiszonki kukurydzy i obornika bydlęcego za pomocą ADM1 : charakterystyka wsadu surowcowego. Część 1
Autorzy:
Klimiuk, E.
Gusiatin, Z. M.
Bułkowska, K.
Pokój, T.
Rynkowska, S.
Powiązania:
https://bibliotekanauki.pl/articles/205022.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cattle manure
maize silage
anaerobic digestion
ADM1 modeling
obornik bydlęcy
kiszonka z kukurydzy
fermentacja beztlenowa
modelowanie ADM1
Opis:
This paper presents the results of fractionation of particulate and soluble organic matter in a mixture of maize silage and cattle manure (49:51% volatile solids) that was used as a feedstock for anaerobic digestion. The extended Weender’s analysis was adapted to measure raw protein, raw lipids, fraction of carbohydrates (including starch, cellulose, hemicelluloses) and lignin. The content of individual fractions in composite, Xc (as kg COD kg-1 COD) was: 0.111 proteins, 0.048 lipids, 0.500 carbohydrates and 0.341 inerts. The biodegradability of Xc was 68%. Based on material balance, the carbon concentration in Xc was 0.0326 kmol C kg-1 COD, whereas nitrogen concentration 0.0018 kmol N kg-1 COD. The estimated pH of the feedstock based on acid-base equilibrium corresponded to the actual value (pH 7.14).
W pracy przedstawiono wyniki stężenia substancji chemicznych rozpuszczonych i nierozpuszczonych w mieszaninie kiszonki kukurydzy zwyczajnej i obornika bydlęcego (49:51% suchej masy organicznej), który wykorzystano jako substrat do wytwarzania biogazu. Do frakcjonowania nierozpuszczalnych związków organicznych, stanowiących kompozyt (Xc), wykorzystano metodę Weender’a. Udział poszczególnych frakcji (jako ChZT) w kompozycie wyniósł: białka - 0,111, tłuszcze - 0,048, węglowodany - 0,500 oraz związki inertne - 0,341. Stężenie związków biodegradowalnych w kompozycie wyniosło 68%. Na podstawie bilansu materiałowego węgla i azotu obliczono, że stężenie węgla w kompozycie wynosi 0,0326 kmol C kg-1 ChZT, zaś azotu 0,0018 kmol N kg-1 ChZT. Odczyn (pH) wsadu surowcowego wyznaczony z równowagi kwasowo-zasadowej odpowiadał rzeczywistemu, tj. 7,14.
Źródło:
Archives of Environmental Protection; 2015, 41, 3; 11-19
2083-4772
2083-4810
Pojawia się w:
Archives of Environmental Protection
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acute phase response in the primiparous dairy cows after repeated percutaneous liver biopsy during the transition period
Autorzy:
Jawor, P.
Brzozowska, B.
Sloniewski, K.
Kowalski, Z.M.
Stefaniak, T.
Powiązania:
https://bibliotekanauki.pl/articles/30733.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
The aim of this study was to evaluate the acute phase response of dairy cows to repeated liver biopsy in order to estimate the safety of this procedure during the transition period. Liver biopsies (up to 1000 mg of liver tissue) were conducted twice a day, 7 days before expected parturition and 3 days after calving. The number of needle insertions for each biopsy was recorded and was dependent on the amount of obtained tissue. Blood samples were taken on day 7 before expected parturition, then on days 3, 4, 7 and 14 after calving. Body temperature was measured daily in all 30 cows from day 3 until day 14 after calving. The concentrations of haptoglobin, serum amyloid A, fibrinogen and interleukin-6 were determined in serum and plasma. In 16.7% of cows, the rectal body temperature rose by ≥ 0.5oC on the day after liver biopsy. Although the concentrations of haptoglobin, serum amyloid A and fibrinogen increased significantly after calving (p<0.01), there was no influence of the number of biopsies on the acute phase reaction and repeated biopsy during the transition period had no effect on body temperature. Therefore, the procedure may be regarded as safe for cows during the transition period.
Źródło:
Polish Journal of Veterinary Sciences; 2016, 19, 2
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Why are dairy cows not able to cope with the subacute ruminal acidosis?
Autorzy:
Brzozowska, A M
Sloniewski, K
Oprzadek, J
Sobiech, P.
Kowalski, Z M
Powiązania:
https://bibliotekanauki.pl/articles/31813.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
One of the largest challenges for the dairy industry is to provide cows with a diet which is highly energetic but does not negatively affect their rumens’ functions. In highly productive dairy cows, feeding diets rich in readily fermentable carbohydrates provides energy precursors needed for maximum milk production, but simultaneously decreases ruminal pH, leading to a widespread prevalence of subacute ruminal acidosis. Maximizing milk production without triggering rumen acidosis still challenges dairy farmers, who try to prevent prolonged bouts of low ruminal pH mainly by proper nutrition and management practices. The animals try to avoid overeating fermentable feeds, as it causes negative consequences by disturbing digestive processes. The results of several experiments show that ruminants, including sheep and beef cattle, are able to modify some aspects of feeding behaviour in order to adjust nutrient intake to their needs and simultaneously prevent physiological disturbances. Particularly, such changes (e.g., increased preference for fibrous feeds, reduced intake of concentrates) were observed in animals, which were trying to prevent the excessive drop of rumen fluid pH. Thanks to a specific mechanism called “the postingestive feedback”, animals should be able to work out such a balance in intake, so they do not suffer either from hunger or from negative effects of over-ingesting the fermentable carbohydrates. This way, an acidosis should not be a frequent problem in ruminants. However, prolonged periods of excessively decreased rumen pH are still a concern in dairy cows. It raises a question, why the regulation of feed intake by postingestive feedback does not help to maintain stable rumen environment in dairy cows?
Źródło:
Polish Journal of Veterinary Sciences; 2013, 16, 4
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Insulin-like growth factors 1 and 2 (IGF-1 and IGF-2) mRNA levels in relation to the gastrointestinal tract (GIT)development in newborn calves
Autorzy:
Flaga, J.
Gorka, P.
Kowalski, Z.M.
Kaczor, U.
Pietrzak, P.
Zabielski, R.
Powiązania:
https://bibliotekanauki.pl/articles/31097.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
The study was aimed at determining the age-depended changes in insulin-like growth factors 1 and 2 (IGF-1 and IGF-2) mRNA levels in relation to the gastrointestinal tract (GIT) development in newborn calves. Twenty four male calves (5-day-old) were randomly allocated to 4 groups which were slaughtered at day 5, 12, 19 and 26 of their life, respectively. Tissue samples from the rumen, abomasum, duodenum, jejunum and liver were taken for analysis, and the level of IGF-1 and IGF-2 mRNA was determined using RT semi-quantitative PCR method. Both IGF-1 and IGF-2 mRNA level was the biggest on 5 day of life, significantly decreased up to day 12-19 in most of analyzed GIT parts, and started to increase thereafter. In the rumen the reduction in the amount of IGFs transcripts was associated with the reduction in papillae length and tunica muscularis thickness. The abomasum weight and tunica mucosa thickness increased from the 5 day up to 19 day of life, whereas abomasal IGF-1 mRNA level decreased together with calf's age up to 19 day of life, and the level of IGF-2 mRNA did not change. The reduction in IGFs mRNA level after 5 day of life in the duodenum (IGF-1 and IGF-2) and in the jejunum (IGF-1) was associated with reduction in villi length (duodenum and jejunum), and the increase of crypt depth (duodenum).
Źródło:
Polish Journal of Veterinary Sciences; 2011, 14, 4
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 465

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