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排序方式: 共有57条查询结果,搜索用时 15 毫秒
41.
Lukic S Bornschein B Drexlin G Glück F Kazachenko O Schöppner M Weinheimer Ch Zoll MC 《The Review of scientific instruments》2011,82(1):013303
An electron-impact ion source based on photoelectron emission was developed for ionization of gases at pressures below 10(-4) mbar in an axial magnetic field in the order of 5?T. The ion source applies only dc fields, which makes it suitable for use in the presence of equipment sensitive to radio-frequency (RF) fields. The ion source was successfully tested under varying conditions regarding pressure, magnetic field, and magnetic-field gradient, and the results were studied with the help of simulations. The processes in the ion source are well understood, and possibilities for further optimization of generated ion currents are clarified. 相似文献
42.
43.
Botrytis rot (Botrytis cinerea) is a serious disease of fruit and vegetables around the globe. Botrytis rot is a problem not only in the field, but during storage, transit, and marketing, due to onset of severe rot on ripe produce. Fungal growth is promoted by warm temperatures and high humidity although other factors could play a role. Mechanical stimulation via vibroacoustic energy is known to affect the growth of organisms but is little studied in food safety of crop transportation and storage. We test whether mechanical energy in the form of vibrations and acoustic frequencies from in-store refrigerators and cold-storage units affect the growth rate of botrytis rot. We also test a broad range of single tones (frequency, Hz) and dyads (2-tone chords) from 110 to 25,088 Hz to determine if particular frequencies have differential effects on the growth of botrytis rot. Playback of vibroacoustic recordings of refrigerator units increased the growth of botrytis rot by 13–18%, on average, suggesting that acoustic output from storage units could promote the mold during transport, storage or within grocery stores. Increased fungal growth rate appears to be stimulated by high frequencies, above 5,000 Hz. Additionally, low frequencies below 165 Hz can reduce botrytis rot growth rate suggesting that exposure to very low frequency ranges could be used to control the fungus. Results of this study open new perspectives on how vibroacoustic output from electronic devices and machines may affect food quality and fungal contamination on fruit, flowers, and vegetable produce. 相似文献
44.
Dusan Bucevac Snezana Boskovic Branko Matovic Vladimir Krstic 《Ceramics International》2010,36(7):2181-2188
SiC–TiB2 composites with up to 50 vol% TiB2 were fabricated by in-situ reaction between TiO2, B4C and C. The densification of the uniaxially pressed samples was done using pressureless sintering in the presence of sintering aids consisting of Al2O3 and Y2O3. The influence of the volume fraction of TiB2 and sintering temperature on density and fracture toughness was examined. It was found that fracture toughness is strongly affected by the volume fraction of TiB2. The presence of TiB2 particles suppresses the grain growth of SiC and facilitates different toughening mechanisms to operate which, in turn, increases fracture toughness of the composite. The highest value for fracture toughness of 5.7 MPa m1/2 was measured in samples with 30 vol% TiB2 sintered at 1940 °C. 相似文献
45.
Marija Smiljkovic Dr. Minos‐Timotheos Matsoukas Dr. Eftichia Kritsi Dr. Urska Zelenko Dr. Simona Golic Grdadolnik Dr. Ricardo C. Calhelha Dr. Isabel C. F. R. Ferreira Dr. Snezana Sankovic‐Babic Dr. Jasmina Glamoclija Dr. Theano Fotopoulou Dr. Maria Koufaki Dr. Panagiotis Zoumpoulakis Dr. Marina Sokovic 《ChemMedChem》2018,13(3):251-258
Four heteroaromatic compounds bearing nitrate esters were selected using a virtual‐screening procedure as putative sterol 14α‐demethylase (CYP51) Candida albicans inhibitors. Compounds were examined for their inhibition on C. albicans growth and biofilm formation as well as for their toxicity. NMR spectroscopy studies, in silico docking, and molecular dynamics simulations were used to investigate further the selectivity of these compounds to fungal CYP51. All compounds exhibited good antimicrobial properties, indicated with low minimal inhibitory concentrations and ability to inhibit formation of fungal biofilm. Moreover, all of the compounds had the ability to inhibit growth of C. albicans cells. N‐(2‐Nitrooxyethyl)‐1Η‐indole‐2‐carboxamide was the only compound with selectivity on C. albicans CYP51 that did not exhibit cytotoxic effect on cells isolated from liver and should be further investigated for selective application in new leads for the treatment of candidiasis. 相似文献
46.
Radomir Slavkovic Zvonimir Jugovic Snezana Dragicevic Aleksandar Jovicic Vladimir Slavkovic 《Computers & Industrial Engineering》2013,64(3):850-857
In this paper, a method of floating ball wear rate identification, using two machine-learning techniques Support Vector Machine (SVM) and Improved Support Vector Machine (ISVM) are proposed. Both models are used to relate the wear rate and technological parameters of the wear resistant drip moulding using different kernel functions. The models for determining the wear rate of white iron casting with low chromium content (flotation balls), was trained and tested by using the existing exploitation data from the Bor Flotation Plant, Serbia. In order to select the best model parameters the statistical indicators for both models are presented. Results show that the ERBF (SVM) and ERBF+POLY (ISVM) achieved the best classification accuracy compare to other kernels used: the absolute mean error of ERB (SVM) is 5.85%, while the error of ERBF+POLY (ISVM) is 6.67%. The tuned ISVM model with mixture of kernels is able to accurately predict the wear rate and can be used to define the optimum chromium content in liquid metal alloys for the casting of flotation balls. 相似文献
47.
Branka Filipovic Snezana Lukic Dragana Mijac Marija Marjanovic-Haljilji Marko Vojnovic Jelena Bogdanovic Tijana Glisic Natasa Filipovic Jamal Al Kiswani Aleksandra Djokovic Suncica Kapor Slobodan Kapor Zoran Bukumiric Ana Starcevic 《International journal of molecular sciences》2021,22(24)
Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease which is characterized by extremely complex pathogenetic mechanisms and multifactorial etiology. Some of the many pathophysiological mechanisms involved in the development of NAFLD include oxidative stress, impaired mitochondrial metabolism, inflammation, gut microbiota, and interaction between the brain-liver-axis and the regulation of hepatic lipid metabolism. The new therapeutic approaches in the treatment of NAFLD are targeting some of these milestones along the pathophysiological pathway and include drugs like agonists of peroxisome proliferator-activated receptors (PPARs), glucagon-like peptide-1 (GLP-1) agonists, sodium/glucose transport protein 2 (SGLT2) inhibitors, farnesoid X receptor (FXR) agonists, probiotics, and symbiotics. Further efforts in biomedical sciences should focus on the investigation of the relationship between the microbiome, liver metabolism, and response to inflammation, systemic consequences of metabolic syndrome. 相似文献
48.
Yakovlev A.B. Lukic M.V. Elsherbeni A.Z. Smith C.E. Steer M.B. 《Microwave and Wireless Components Letters, IEEE》2003,13(3):125-127
In this work, we present a multilayered waveguide transition containing several interacting printed antenna arrays for spatial power combining applications. Narrow-band resonant rectangular slot antennas used in earlier designs are replaced by meander-slot antennas and their modifications, in order to increase the frequency bandwidth and efficiency of the system. Numerical results for finite arrays of meander-slot and U-slot antennas show significant advantages in scattering characteristics in comparison to traditionally used rectangular slot antenna arrays. 相似文献
49.
The analysis of an optimal placement of HVDC links to an AC network is considered from the point of view of DC power flow control on system dynamics. The analysis is based upon a system dynamic model developed and the use of transfer functions involving the system sensitivity analysis with respect to converter current control. An example is carried out on a 13-bus, four-generator test system illustrating the feasibility of the approach developed. 相似文献
50.
Comprehensive drive train efficiency analysis of hybrid electric and fuel cell vehicles based on motor-controller efficiency modeling 总被引:3,自引:0,他引:3
From the point of view of overall hybrid electric vehicle (HEV) and fuel cell vehicle (FCV) drive train efficiency, the research focus is mainly on the efficiency analysis of the power train components, which prove to be an integral part of modern HEV and FCV drive trains. The critical portion of any HEV electrical system consists of a power electronic converter (inverter) and a suitable traction motor. Thus, the efficiency analysis of the inverter/motor is of prime importance for the calculation of the overall efficiency of the drive trains. This paper aims at modeling the efficiencies of the traction motor/controller through efficiency maps. Efficiency maps are a convenient way to represent motor drive systems of large and complex systems, like that of a HEV. The paper uses the advanced vehicle simulator (ADVISOR) software for the simulations of a large-sized car, similar to a Chevy Lumina, over the urban dynamometer-driving schedule and highway fuel economy test drive cycles. Furthermore, the paper investigates the traction motor efficiency maps and consequent overall drive train efficiencies of commercially available Honda Insight and Toyota Prius HEVs. In all the case studies, the aim is to analyze the overall drive train efficiency over the city and highway drive cycles based on the inverter/motor efficiency maps. 相似文献