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排序方式: 共有133条查询结果,搜索用时 9 毫秒
1.
Feruglio S. Fouad Hanna V. Alquie G. Vasilescu G. 《IEEE transactions on instrumentation and measurement》2006,55(6):1892-1903
In this paper, analytical expressions of dark currents and equivalent noise generators of a CMOS color image sensor are presented, and the signal-to-noise ratio (SNR) at both outputs is evaluated. Static measurements and simulations on Austria Micro Systems 0.35-mum CMOS test structures yield guidelines to increase the SNR of the buried double junction photodetector 相似文献
2.
Liliana Marinescu Denisa Ficai Anton Ficai Ovidiu Oprea Adrian Ionut Nicoara Bogdan Stefan Vasile Laura Boanta Alexandru Marin Ecaterina Andronescu Alina-Maria Holban 《International journal of molecular sciences》2022,23(11)
The synthesis of nanoparticles from noble metals has received high attention from researchers due to their unique properties and their wide range of applications. Silver nanoparticles (AgNPs), in particular, show a remarkable inhibitory effect against microorganisms and viruses. Various methods have been developed to obtain AgNPs, however the stability of such nanostructures over time is still challenging. Researchers attempt to obtain particular shapes and sizes in order to tailor AgNPs properties for specific areas, such as biochemistry, biology, agriculture, electronics, medicine, and industry. The aim of this study was to design AgNPs with improved antimicrobial characteristics and stability. Two different wet chemical routes were considered: synthesis being performed (i) reduction method at room temperatures and (ii) solvothermal method at high temperature. Here, we show that the antimicrobial properties of the obtained AgNPs, are influenced by their synthesis route, which impact on the size and shape of the structures. This work analyses and compares the antimicrobial properties of the obtained AgNPs, based on their structure, sizes and morphologies which are influenced, in turn, not only by the type or quantities of precursors used but also by the temperature of the reaction. Generally, AgNPs obtained by solvothermal, at raised temperature, registered better antimicrobial activity as compared to NPs obtained by reduction method at room temperature. 相似文献
3.
The properties of the surface films formed on Ti and its Ti–5Al–4V and Ti–6Al–3.5Fe alloys by chemical (immersion in 10 M NaOH) and thermal treatment (500 °C) were studied in this paper. Their corrosion behaviour in Ringer solution was investigated. After treatments, the sample microhardness was measured. Also, the sample surfaces were observed by an optical microscope before and after immersion in Ringer solutions. The electrochemical behaviour of the surface films obtained by the chemical and thermal treatments was studied using the methods of the electrochemical impedance spectroscopy (EIS) and monitoring of open circuit potentials at different immersion periods (up to 60 days) in Ringer solution. Microhardness increased with the increasing loads for the studied materials, showing the existence of a compact protective layer. Microscopic observations exhibited more compact coatings after 60 days of exposure in Ringer solution, due to the formation of an apatite layer. EIS spectra revealed surface films with two layers: an inner, barrier protective layer and an outer, porous apatite layer. The impedance increases in time denoting that the films have grown by apatite nucleation. Also, EIS spectra showed that the complex treatment by chemical + heat method is the most efficiently. For the samples treated by the two processes (chemical + heat) the values of the open circuit potentials are nobler than of the chemical treated samples, denoting better protective, bioactive films. 相似文献
4.
Joanna Dawczyk Ecaterina Ware Mahmoud Ardakani Joe Russo Hugh Spikes 《Tribology Letters》2018,66(4):155
Focussed ion beam milling (FIB) followed by TEM has been used to study ZDDP tribofilms on rubbed steel surfaces. It has been found that the impact of high energy platinum and gallium ions during FIB causes significant morphological and structural changes to the uppermost 30–50 nm of a ZDDP tribofilm. This can be prevented by the low energy deposition of a quite thick gold layer prior to installation of the sample in the FIB facility. This problem, and its solution, have been quite widely reported in the non-tribology literature but have not previously been highlighted in the application of FIB to study tribological surfaces. It has also been found, using this gold pre-deposition method, that the bulk of the ZDDP tribofilm studied has a polycrystalline structure. 相似文献
5.
Sorption/release of diclofenac sodium in/from free‐standing poly(acrylic acid)/poly(ethyleneimine) multilayer films 下载免费PDF全文
Polyelectrolyte multilayer films deposited onto various substrates have been used extensively as drug delivery systems. However, little attention has been paid to the release of drugs from free‐standing polymeric films. Herein, we report the construction of thermal crosslinked free‐standing poly(acrylic acid) (PAA)/branched poly(ethyleneimine) (PEI) multilayer films composed of 25 double layers [(PAA/PEI)25] and their use in sorption/release of diclofenac sodium (DS). The (PAA/PEI)25 multilayer films were characterized by scanning electron microscopy, potentiometric titrations and Fourier transform infrared spectroscopy, while the sorption/release of DS was monitored by UV – Vis spectroscopy. The DS sorption equilibrium data were fitted with five isotherm models (Langmuir, Freundlich, Sips, Dubinin–Radushkevich, and Temkin). The maximum equilibrium sorption capacity, qm, given by the Langmuir model was 32.42 mg DS/g. The Korsmeyer–Peppas semiempirical equation showed that the release of DS from the free‐standing (PAA/PEI)25 films proceeded by pseudo‐Fickian diffusion, irrespective of the releasing media. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43752. 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.
The interest for the primary solid tumors of the mesentery (TSPM) is justified by the difficulties of preoperative diagnosis and surgical treatment of these unusual lesions. We analyzed 68 TSPM operated in the Department of General Surgery of Fundeni Hospital between 1960-1993. In the study were included only the lymphoma presented as mesenteric masses (n = 17); the enlarged mesenteric lymph nodes were excluded. The most common malignant tumor was the fibroma (n = 8) and lipoma (n = 10). In the resection of mesenteric tumors exposure of the superior mesenteric vessels is important. The relation between tumoral and superior mesenteric vessels is the necessary criterion of resectability: in 41 cases from 43 unresectable lesions the reason of unresectability was the invasion of the superior mesenteric vein and artery; in only two cases the reason was the presence of liver metastases. The resectability was not influenced by the multiplicity of the lesions: in all cases with multiple mesenteric tumors (6 patients) the resection was performed. The distant metastases of TSPM are rare; on the contrary, the local invasion is common. 相似文献
8.
Theoretical and experimental aspects on the specific interactions developed via electrostatic interactions and hydrogen‐bonding in a ternary system formed of a proton‐donor solvent (N,N‐dimethylformamide or methanol), a proton‐acceptor solvent (water), and a quaternized polysulfone with various contents of ionic chlorine, which indicates a proton‐acceptor character, are investigated. Thus, the interactions of the ternary systems are corrected on the basis of the association phenomena defined through association constants. Numerical values for these constants were evaluated as a function of the system composition, by mathematical simulations for an accurate adjustment of preferential adsorption, determined by the Flory–Huggins–Pouchly theoretical approach applied to the experimental data. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers 相似文献
9.
10.
Surface and interface properties of functionalized polysulfones: Cell‐material interaction and antimicrobial activity 下载免费PDF全文
Quaternized polysulfones with different ionic chlorine content tested for biomedical applications were obtained by quaternization reaction of chloromethylated polysulfones with N,N‐dimethylethanolamine. The relationship between the different physical and chemical characteristics of these polymers and their biocompatible and antimicrobial properties was established for maximizing the selectivity and performance of these materials for biomedical applications. Therefore, topographic reorganization of the polysulfonic films induced by the type of nonsolvent in casting solutions of polymer significantly influences films morphology, depending on the charge density of polyelectrolytes, the hydrophilic/hydrophobic characteristics, as well as on the history of the formed films. Furthermore, the study of the adhesion of red blood cells and cohesion of platelets on the surface of quaternized polysulfone films, as well as analysis of antibacterial activity, using Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 25923 microorganisms, contribute to extending the possible applications of quaternized polysulfones as semipermeable membranes in biomedical domains. POLYM. ENG. SCI., 55:2184–2194, 2015. © 2015 Society of Plastics Engineers 相似文献