Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 132

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 7 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  optimization
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 7 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Application of solid phase microextraction (SPMŁi) and gas chromatography combined with mass spectrometry (GC-MS) for analysis of the chlorophenoxy herbicide residues was studied. The optimal conditions for SPME/GC-MS analysis of chlorophenoxy herbicides were determined as follows: adsorption time 15-20 min at 50°C and desorption time 6 min at 220°C. The highest concentration of MCPA was found in the tissues of the weeds of M. inodora, C. bursa pastoris, while the lowest in A. githago, P. aviculare. In addition to that, in May and June the studied herbicides were found in low quantities in the surface waters of the river of Liwiec.
Today the logistics could be an efficient method for increasing the food production and food processing and they could combine all the elements of food production sub-complex into the single chain providing conditions not only for domestic production and consumption of this strategically important products but also provide a great deal of export flows. In our opinion it is logistics that can consolidate separate components of economic mechanism and provide conditions for structural and functional balance and efficient institutional foundations. When operating logistics flows we can develop optimal cause and effect relationship among the elements that would finally create effective system. As a primary step that would enable to achieve a totally new level in logistics for the food production of Ukraine, the new scheme for transformation mechanism of logistics system in food production sub-complex of Ukraine has been suggested. It is based on “virtualization” of material flows among certified food products storehouses.
Background. Lactobacillus acidophilus not only improves the intestinal flora balance but also inhabits the growth of undesirable microorganisms in intestine, which is benefit to the health of humans and animals. Plackett-Burman and steepest ascent experiment are the rapid and concise ways of screening the main effective factors. This study is aimed to select the main influence factors and optimize the medium for Lactobacillus acidophilus by Plackett-Burman experiment and steepest ascent experiment. Material and methods. The ideal carbon source was screened among glucose, maltose, lactose and whey powder, and the ideal nitrogen source was screened among casein hydrolysate, peptone, yeast extract powder, fish meal, carbamide, ammonium sulfate and sodium nitrate by single factor experiment. Plackett-Burman and steepest ascent experiment were applied to screen the main effective factors of Lactobacillus acidophilus among peptone, beef extract, yeast extract powder, glucose, K2HP04, C6H1407N2, CH3COONa, MgS04 and Tween-80. Result. The results indicated that glucose (p = 0.01510) as negative factor and K,HP04 ip = 0.02017) as positive effect were the significant growth factors of Lactobacillus acidophilus, CH3COONa (p = 0.09273) as positive effect was an important factor, and the optimized medium was as follows: glucose - 21 g/L, K2HP04 - 3.5 g/L, CH3COONa - 6.5 g/L, peptone - 10 g/L, beef extract - 8 g/L, yeast extract powder - 8 g/L, C6H1407N2 - 2 g/L, MgS04 - 0.2 g/L and Tween-80 - 1 mL/L when the maximum viable count could achieve 2.72* 109 cfii/mL. Discussion. The experimental model is reliable and the experimental results are of good stability. Variance analysis is performed to determine the adequacy and significance of the linear model. Thus, Plackett-Burman and steepest ascent experiment improve the veracity of optimization the medium for Lactobacillus acidophilus compared with the previous research.
The study aimed at screening and identifying a potential poly-β-hydroxybutyrate (PHB) accumulating Bacillus strain and optimization of media parameters for increased PHB production by the strain. A Gram-positive bacterium that accumulated PHB was isolated from local garden soil of Bangalore. Based on morphological and physiological properties, and nucleotide sequence (about 1.5 kb) of its 16S rDNA it was identified as Bacillus thuringiensis IAM 12077. PHB production was found to be comparable to most of the Bacillus sp. reported to date. PHB production by this strain was dependent on nutrient limitation. Cell dry weight and PHB accumulation increased significantly under biphasic growth condition (from nutrient broth to nitrogen-deficient medium) as compared with growth in nutrient broth alone (from 0.32 g/l to 2.76 g/l cell dry weight; 24% to 43.37% PHB accumulation; 0.2 g/l to 1.2 g/l PHB production), with maximum accumulation at 24 h in nitrogen-deficient medium. Time course study of growth and PHB production by this strain in the nitrogen deficient medium showed that PHB production was associated with the stationary phase of growth. All the tested media containing different carbon and nitrogen sources supported growth and PHB production. Ultraviolet spectrum of the extracted polymer showed a characteristic peak at 235 nm.
Optimization of structural elements met both in civil and mechanical engineering leads to the concept of a material with characteristics smoothly varying in a certain direction (functionally graded materials). An example of this material is a laminate having macroscopic properties varying in space (functionally graded laminate). The aim of this note is to propose a revisited version of the mathematical model for analyzing the effect of interlaminar microdefects on the macroscopic response of a structural element. It is assumed that the distribution of these defects is represented by its mean density per unit area of every interface.
The difficulties involved in calibration of physically based erosion models have been partly attributable to the lack of robust optimization tools. This paper presents the essential concepts and application to optimize channel and plane parameters in an erosion model, with a global optimization method known as Repulsive Particle Swarm (RPS), a variant of Particle Swarm Optimization (PSO) method. The physically-based erosion model that which was chosen is called WESP (watershed erosion simulation program). The optimization technique was tested with the field data collected in an experimental watershed located in a semi-arid region of Brazil. On the basis of these results, the recommended erosion parameter values for a semi-arid region are given, which could serve as an initial estimate for other similar areas.
In order to obtain the optimal technological parameters of lettuce vacuum osmotic dehydration, the effects of osmotic temperature, slice thickness, sucrose concentration, and vacuum degree on the vacuum osmotic dehydration were explored. The lettuce water loss rate and solid gain rate decreased with the increase of slice thickness and vacuum degree, and increased with the increase of sucrose concentration and osmotic temperature. Response surface methodology was applied to analyze the infl uence of the four infl uential factors on the evaluated parameters and the optimization of lettuce vacuum osmotic dehydration was studied. The results indicated that, within the experimental scope, the optimized technological parameters of lettuce vacuum osmotic dehydration are the temperature of 28º C, the slice thickness of 2 mm, sucrose concentration of 47%, the vacuum degree of 22 kPa, and the water loss rate and solid gain rate are 72.16% and 11.82%, respectively.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 7 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.