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排序方式: 共有188条查询结果,搜索用时 218 毫秒
31.
Kitae Park Kambiz Sadeghi Sarinthip Thanakkasaranee Ye-In Park Junsoo Park Ki-Ho Nam Haksoo Han Jongchul Seo 《International Journal of Applied Ceramic Technology》2021,18(2):302-311
To develop biocompatible antimicrobial agent, oyster shell wastes were thermally calcined at different temperatures ranging from 300 to 1000 °C. The chemical compositions and properties of oyster shells were characterized. As such, crystallographic analysis presented that oyster shells had a hexagonal crystalline shape, and calcination process reduced their crystalline size, volume (grain dimension), and bond length, which strongly affected antimicrobial efficacy. Results showed that the main components of uncalcined and calcined oyster shells were CaCO3 and CaO, by which CaO was found to be the main antimicrobial component. Notably, calcined oyster shells showed antimicrobial potency against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus). Furthermore, cytotoxicity analysis proved that calcined oyster shells had good cell viability and low cytotoxicity. Results highlighted that calcined oyster shells, particularly those treated at 750°C, could be a biocompatible alternative to synthetic biocidal and antimicrobial agents using in food packaging, biomedical, and cosmetic industries. 相似文献
32.
Amina A Attia Badie S Girgis Soheir A Khedr 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2003,78(6):611-619
Two activated carbons were obtained from pistachio shells by impregnation with H3PO4 under standard conditions of acid concentration (50 wt%) and heat treatment at 773 K for 2 h. The soaking time was 24 and 72 h for the two samples before thermal pyrolysis. Analysis of the N2/77 K adsorption isotherms proved that both were highly adsorbing carbons with considerable microporosity, and that the prolonged contact with activant enhanced total porosity (surface area and pore volume) and increased the amount of mesoporosity. Adsorption isotherms of probe molecules, viz methylene blue (MB), rhodamine B (RB), phenol (P) and p‐nitrophenol (PNP), were determined at room temperature, from aqueous solutions. Both the Langmuir and Freundlich model adsorption equations show satisfactory fit to experimental data. Both carbons exhibit similar adsorption parameters irrespective of their porosity characteristics. The sequence of uptake per unit weight was: PNP > MB > RB > P. Low affinity towards phenol may be associated with its competition with water molecules which are more favourably attracted to the acid surface which has a high oxygen functionality. Preferred adsorption in the order PNP > MB > RB is proposed to be a function of carbon porosity, related to the increased molecular dimensions of the solutes. Adsorption from a binary mixture of equal concentrations of MB and RB showed reduced uptake for both sorbates in comparison to the single component experiments. RB removal surpasses that of MB in the binary test and may be attributed to lower water solubility and higher molecular dimensions. Copyright © 2003 Society of Chemical Industry 相似文献
33.
A compact substrate integrated waveguide (SIW) with open complementary split‐ring resonators (OCSRRs) loaded on the waveguide surface is proposed. The OCSRRs can be interpreted in terms of electric dipoles and they are good candidates to behave as electric scatterers. By loading OCSRRs on the waveguide surface, a forward‐wave pass‐band propagating below the waveguide cutoff frequency is generated. The resonance frequency of the OCSRRs is approximately half of the resonance frequency of the complementary split ring resonator (CSRR). Therefore, the electrical size of this particle is larger than the CSRRs and the OCSRRs are more appropriate for the SIW miniaturization. A bandpass response with a sharp rejection frequency band is obtained by properly manipulating the structure of the elements. By changing the orientation of the OCSRRs, two types of unit cell are proposed. Moreover, by resizing the OCSRRs, resonance frequency can be easily moved and the bandwidth can be tuned by the coupling between two OCSRRs. Compared with some other reported bandpass filters (BPFs) with SIW technique, the presented BPF has great improvements on size reduction and selectivity. To verify the methodology, two filters with center frequency of 5.5 GHz are designed and measured. The measured results are in good agreement with the simulated ones. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:674–682, 2016. 相似文献
34.
Payam Masoumi Farahabadi Ali Basaligheh Parvaneh Saffari Kambiz Moez 《Journal of Infrared, Millimeter and Terahertz Waves》2017,38(6):745-765
This paper presents a compact 60-GHz power amplifier utilizing a four-way on-chip parallel power combiner and splitter. The proposed topology provides the capability of combining the output power of four individual power amplifier cores in a compact die area. Each power amplifier core consists of a three-stage common-source amplifier with transformer-coupled impedance matching networks. Fabricated in 65-nm CMOS process, the measured gain of the 0.19-mm2 power amplifier at 60 GHz is 18.8 and 15 dB utilizing 1.4 and 1.0 V supply. Three-decibel band width of 4 GHz and P1dB of 16.9 dBm is measured while consuming 424 mW from a 1.4-V supply. A maximum saturated output power of 18.3 dBm is measured with the 15.9% peak power added efficiency at 60 GHz. The measured insertion loss is 1.9 dB at 60 GHz. The proposed power amplifier achieves the highest power density (power/area) compared to the reported 60-GHz CMOS power amplifiers in 65 nm or older CMOS technologies. 相似文献
35.
Understanding the fundamental aspects of transport through biomaterials is a necessity for a vast range of bio-related studies.
Biofilm formation on the surface of adsorptive media such as granular activated carbon (GAC) has been extensively used to
remove organic materials, nitrogen species, heavy metals, and other contaminants in wastewater treatment. In this study, a
multilayer mass transfer system consisting of the reactor’s bulk fluid, diffusion layer, biofilm, and GAC is modeled. In order
to consider the equilibrium at the interface of biofilm and activated carbon, Freundlich adsorption method is applied. The
interfacial interactions are taken into account in the biodegradation process. The results of model prediction are compared
with the available experimental data and show a very good agreement. The effect of biofilm formation on the reactor porosity
is considered through a porous media approach. Furthermore, the influence of variation in particle diameters on the removal
efficiency is studied. It can be seen that porosity alteration as a result of biofilm formation within the carbon bed has
a noticeable effect on the removal efficiency. 相似文献
36.
Laila B Khalil Badie S Girgis Tarek A
M Tawfik 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2001,76(11):1132-1140
Activated carbons were prepared from olive oil solid wastes by treatment in different schemes: impregnation with H3PO4 followed by pyrolysis at 300–700 °C, by steam pyrolysis at 600–700 °C, or by conventional steam activation at 850 °C. Porosity characteristics were determined by analysis of nitrogen adsorption isotherms, and carbons of widely different properties and surface pH values were obtained. Decomposition of H2O2 in dilute unbuffered solution was followed by measuring evolved oxygen volumetrically. First‐order kinetics was followed, and the catalytic rate coefficients were evaluated. The carbons tested showed appreciable activity where evolved oxygen attained ≈10% of the stoichiometric amount in 1 h. The degree of decomposition showed inverse dependence on surface area, pore volume and mean pore dimensions. The chemical nature of the surface, rather than the porosity characteristics, was the principal factor in enhancing the disproportionation of H2O2 on the activated carbon surface. © 2001 Society of Chemical Industry 相似文献
37.
Works pertinent to arterial transport models are analyzed and a critical assessment of the models utilized in the study of fluid flow and mass transfer within the arteries is presented with an emphasis on the role of porous media. Arterial transport models are assessed and classified based on their ability to physically prescribe the arterial anatomy as well as the related transport processes. Pertinent models such as wall-free, homogeneous-wall, and multi-layer models as well as the governing equations and different types of boundary conditions utilized in each model are analyzed. 相似文献
38.
Scientometrics - Zone identification is a topic in the area of text mining which helps researchers be benefited by the content of scientific papers in a satisfactory manner. The major aim of zone... 相似文献
39.
Wireless Networks - Each sensor in WSNs receives data from the limited area under its coverage. The received data is processed by the sensor; then, it is wirelessly transmitted to the sink.... 相似文献
40.
Oronzio Manca Sergio Nardini Khalil Khanafer Kambiz Vafai 《Numerical Heat Transfer, Part A: Applications》2013,63(3):259-282
Mixed convection in an open cavity with a heated wall bounded by a horizontally insulated plate is studied numerically. Three basic heating modes are considered: (a) the heated wall is on the inflow side (assisting flow); (b) the heated wall is on the outflow side (opposing flow); and (c) the heated wall is the horizontal surface of the cavity (heating from below). Mixed convection fluid flow and heat transfer within the cavity is governed by the buoyancy parameter, Richardson number (Ri), and Reynolds number (Re). The results are reported in terms of streamlines, isotherms, wall temperature, and the velocity profiles in the cavity for Ri=0.1 and 100, Re=100 and 1000, and the ratio between the channel and cavity heights (H/D) is in the range 0.1-1.5. The present results show that the maximum temperature values decrease as the Reynolds and the Richardson numbers increase. The effect of the H/D ratio is found to play a significant role on streamline and isotherm patterns for differentheating configurations. The present investigation shows that the opposing forced flow configuration has the highest thermal performance in terms of both maximum temperature and average Nusselt number. 相似文献