排序方式: 共有151条查询结果,搜索用时 15 毫秒
1.
This article represents the result of experimental research on transient heat transfer in a multilayered (heterogeneous) wall. Our non-steady thermal transmission simulation is based on a finite-difference calculation method. The value of a Fourier number shows the similarity of thermal variation in conditional layers of an enclosure. Most scientists recommend using no more than a value of 0.5 for the Fourier number when performing calculations on dynamic (transient) heat transfer. The value of the Fourier number is determined in order to acquire reliable calculation results with optimal accuracy. To compare the results of simulation with experimental research, a transient heat transfer calculation spreadsheet was created. Our research has shown that a Fourier number of around 0.5 or even 0.32 is not sufficient (\({\approx }17\,\%\) of oscillation amplitude) for calculations of transient heat transfer in a multilayered wall. The least distorted calculation results were obtained when the multilayered enclosure was divided into conditional layers with almost equal Fourier number values and when the value of the Fourier number was around 1/6, i.e., approximately 0.17. Statistical deviation analysis using the Statistical Analysis System was applied to assess the accuracy of the spreadsheet calculation and was developed on the basis of our established methodology. The mean and median absolute error as well as their confidence intervals has been estimated by the two methods with optimal accuracy (\({F}_{\mathrm{oMDF}}= 0.177\) and \(F_{\mathrm{oEPS}}= 0.1633\) values). 相似文献
2.
Edita Zubrytė Danutė Kaušpėdienė Romas Ragauskas Rima Binkienė Aušra Selskienė 《分离科学与技术》2020,55(16):2855-2868
ABSTRACT A non-hazardous groundwater treatment waste (GWTW) was examined as a low-cost sorbent for Pb(II) and Cu(II) ions. The content of the dominant elements in GWTW was as follows: 78% Fe2O3, 7.4% P2O5, 7.4% CaO and 5.2% SiO2. The removal of Pb(II) and Cu(II) was fast, and more than 67–95% of ions were accumulated by GWTW during the first 3 min. The sorption capacity of GWTW depends on solution pH, concentration and temperature. Equilibrium data fitted well with Langmuir–Freundlich and Langmuir-partition models. The inherently formed nano-adsorbent could be utilized for the treatment of water contaminated with Pb(II) and Cu(II) ions. 相似文献
3.
A. Balčiūnaitė Z. Sukackienė K. Antanavičiūtė J. Vaičiūnienė A. Naujokaitis L. Tamašauskaitė-Tamašiūnaitė E. Norkus 《International Journal of Hydrogen Energy》2021,46(2):1989-1996
Effective Co/Cu, CoB/Cu, and CoBM (M = Mo,Zn,Fe)/Cu catalysts were prepared on the copper surface by a simple electroless deposition method using a morpholine borane as a reducing agent in the glycine solution. The activity of the deposited catalysts was investigated for hydrogen generation from an alkaline sodium borohydride solution. It was determined that these synthesized catalysts demonstrated the catalytic activity for the hydrolysis reaction of NaBH4. The lowest obtained activation energy (EA) of the hydrolysis reaction of NaBH4was 27 kJ mol?1 for the CoBMo/Cu catalyst. The hydrogen generation rate of 15.30 ml min?1 was achieved using CoBMo/Cu catalysts at 313 K and it increased ~3.5 times with the increase of temperature to 343 K. The highest hydrogen generation rate obtained by CoBMo/Cu films may be related to the hierarchical cauliflower-shaped 3D structures and the high roughness surface area. Moreover, the CoBMo/Cu catalyst showed an excellent reusability. 相似文献
4.
5.
The Antimicrobial Effect of Spice‐Based Marinades against Campylobacter jejuni on Contaminated Fresh Broiler Wings 下载免费PDF全文
Gintarė Zakarienė Anita Rokaitytė Sigita Ramonaitė Aleksandr Novoslavskij Kristina Mulkytė Gintarė Zaborskienė Mindaugas Malakauskas 《Journal of food science》2015,80(3):M627-M634
The antimicrobial effect of spice‐based marinades against Campylobacter jejuni on inoculated fresh broiler wings was investigated. Experiments were carried out with 1 strain of C. jejuni and 6 marinades. Four experimental marinades were composed for the study and contained spices (thyme, rosemary, basil, marjoram, and so on) and different combination of bioactive compounds. Two marinades were commercial and contained spices (black pepper, sweet red pepper, and so on) and chemical additives (monosodium glutamate, sodium diacetate, calcium lactate), 1 commercial marinade was also enriched with bioactive compounds (linalool, cinnamaldehyde, lactic acid). Total aerobic bacterial count was examined to estimate the possible effect of tested marinades on the shelf‐life of marinated broiler wings. Study revealed that thyme‐based marinade was the most effective against C. jejuni on broiler wings and reduced the numbers of campylobacters by 1.04 log colony forming unit (CFU)/g (P ≤ 0.05) during storage for 168 h at 4 °C temperature. Moreover, it was more effective against C. jejuni than commercial marinade with 0.47 log CFU/g (P ≤ 0.05) reduction effect. Both experimental and commercial marinades had very similar effect on the total aerobic bacterial count. Although experimental and commercial marinades had different effect on pH of broiler wings, this parameter did not show a major impact on the antimicrobial effect of tested marinades (P ≥ 0.05). Our study shows that experimental natural thyme‐based marinade can reduce numbers of C. jejuni more effectively than tested commercial marinades. 相似文献
6.
Monica Popa Jose Maria Calderon Moreno Cora Vasilescu Silviu Iulian Drob Elena Ionela Neacsu Andrej Coer Julija Hmeljak Gregor Zerjav Ingrid Milošev 《Metallurgical and Materials Transactions A》2014,45(7):3130-3143
This article analyses the microstructure, electrochemical behavior, and biocompatibility of a novel Ti-20Nb-10Zr-5Ta alloy with low Young’s modulus (59 GPa) much closer to that of bone, between 10 and 30 GPa, than Ti and other Ti alloys used as implant biomaterial. XRD and SEM measurements revealed a near β crystalline microstructure containing β phase matrix and secondary α phase, with a typical grain size of around 200 μm. The corrosion behavior in neutral Ringer solution evidenced: self-passivation behavior characterizing a very resistant passive film; an easy passivation as a result of favorable influence of the alloying elements Nb, Zr, and Ta that participate with their passive oxides to the formation of the alloy passive film; low corrosion and ion release rates corresponding with very low toxicity. In MEM solution, the novel alloy demonstrated very high corrosion resistance and no susceptibility to localized corrosion. Biocompatibility was evaluated on in vitro human osteoblast-like and human immortalized pulmonary fibroblast cell (Wi-38) lines and the new Ti-20Nb-10Zr-5Ta alloy exhibited no cytotoxicity. The new Ti-20Nb-10Zr5Ta alloy is a promising material for implants due to combined properties of low elastic modulus, very low corrosion rate, and good biocompatibility. 相似文献
7.
Julija Josic Anna Tholén Olsson Jennie Wickeberg Sandra Lindstedt Joanna Hlebowicz 《Nutrition journal》2010,9(1):63
Background
Results of epidemiological studies have suggested that consumption of green tea could lower the risk of type 2 diabetes. Intervention studies show that green tea may decrease blood glucose levels, and also increase satiety. This study was conducted to examine the postprandial effects of green tea on glucose levels, glycemic index, insulin levels and satiety in healthy individuals after the consumption of a meal including green tea. 相似文献8.
Danguolė Raklevičienė Regina Losinska Danguolė Švegždienė 《Microgravity science and technology》2011,23(2):227-233
Responses of cress (Lepidium sativum L.) seedling leaves to separate and simultaneous illumination with red (660 nm) and far-red (735 nm) light were studied under
fast clinorotation (50 rpm) and usual gravity (1g) conditions. The monochromatic light emitting diodes (LEDs) have been used
for illumination of seedlings from above. The growth and spatial orientation of leaves and the location of presumable gravisensors
in petioles were analysed. Clinorotation in the dark promoted the radial expansion of leaf lamina and unfolding of leaves.
It was shown that clinorotation in red light inhibited significantly the elongation of petioles as compared with that under
the action of gravity force. Simultaneous red and far-red illumination promoted the growth of petioles under clinorotation,
but did not affect the orientation of laminas, which remained the same as of the 1-g control ones. Red light, applied separately
and simultaneously with far-red light, guided the bending of laminas as well as the unfolding of leaf petioles in both usual
and clinorotation conditions. Histological and cytological analyses of petioles revealed the presence of movable amyloplasts
in endodermic cells in proximal region of petioles. Comparison of intracellular positioning of amyloplasts in petioles of
leaves grown under clinorotation and the action of gravity allows a presumption that these plastids may be identified as gravisensors
of garden cress leaves. The obtained data imply that clinorotation and exposition to monochromatic red light or simultaneous
illumination by red and far-red light affect the elongation of petioles of cress seedling leaves. Spectral components guide
the unfolding of laminas in a gravity-independent manner. 相似文献
9.
A. Survila Z. Mockus R. Juškėnas V. Jasulaitienė 《Journal of Applied Electrochemistry》2001,31(10):1109-1116
Optimal conditions for Sn and Co codeposition were achieved in slightly acid citrate solutions containing no excess of ligand. Sn–Co coatings were deposited with amounts of Co ranging from 15 to 86 mass %. Bright deposits were obtained when the Co content exceeded 76%. These coatings may be considered as solid solutions of tin in -Co and -Co. The -Sn phase is predominant in the case of coatings containing less Co. Voltammograms of the partial processes of Sn(II) and Co(II) reduction may be described quantitatively with the proviso that SnL2– and CoLH– are electrically active complexes. 相似文献
10.
Vidmantas Dikinis Violeta Rėzaitė Irina Demčenko Algirdas Seiskis Tauras Bernatavičius 《金属精饰学会汇刊》2013,91(3-4):98-104
The influence of the components of an acidic solution: Cr(III) nitrate-malonic acid-Co(II) salt and treatment conditions on zinc dissolution and formation of Chromate films as well as on their decorative and protective properties have been studied using the analytical, XPS, structural and accelerated corrosion test methods. An organic acid is the main component, which has an essential influence on zinc dissolution and formation of Chromate films as well as their decorative and protective properties. The influence of organic acid is directly related with the state of the Cr3+ ions in chromating solution. When the Cr3+ ions are in the form of hexaaquaions, the organic acid increases the quantities of the zinc dissolved and the Cr(III) deposited on the zinc surface (especially at 60°C). It also predetermines the formation of a thick, porous Chromate film with large cracks at 60°C. Its decorative and protective properties are rather poor. When Cr3+ ions are in the form of a complex with organic acid, the quantities of the zinc dissolved and the Cr(III) deposited on the zinc surface significantly decrease and thinner Chromate films with an even surface, good decorative appearance and high corrosion resistance are formed Decorative blue-bright Cr(VI)-free films with a slight iridescent tint, obtained in solution, containing Cr(III) nitrate (0.2), malonic acid (0.3) and Co(II) nitrate (0.02) mol dm?3, at p H 1.6-2.0 at room temperature over 30–60 s, possess corrosion resistance (192–240 h in a salt spray chamber) similar to that of iridescent Chromate films, obtained in acidic Cr(VI) solution. 相似文献