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91.
Mallikharjuna Rao Komarneni Zhongqing Yu Uwe Burghaus Yulia Tsverin Alla Zak Yishay Feldman Reshef Tenne 《Israel journal of chemistry》2012,52(11-12):1053-1062
A reactivity screening of new nano-hydrodesulfurization (HDS) catalysts was conducted using an ambient pressure flow reactor as well as ultra-high vacuum kinetics techniques. Thiophene was used as a probe molecule. Clean multiwall WS2 nanotubes (INT-WS2) as well as Ni- and Co-coated INT-WS2 were considered. In addition, undoped MoS2 and Re-doped nanoparticles with fullerene-like structures were studied. Commercial Ni and Co HDS catalysts from Haldor Topsoe (Denmark) as well as “nano MoS2” from Impex Corp. (USA) were considered as reference materials. The lab-synthesized and commercial systems broke down thiophene into quite similar non-sulfur containing products, as identified by a gas chromatograph. The Ni and Co promoted catalysts showed similar thiophene conversion rates. Although the commercial catalysts had larger thiophene conversion rates than the laboratory-synthesized systems, the Re-doped nano-HDS catalyst showed quite low rates of formation of H2S, an undesirable by-product. 相似文献
92.
This paper presents a tree-based framework for producing self-dual morphological operators, based on a tree-representation complete inf-semilattice (CISL). The idea is to use a self-dual tree transform to map a given image into the above CISL, perform one or more morphological operations there, and map the result back to the image domain using the inverse tree transform. We also present a particular case of this general framework, involving a new tree transform, the Extrema-Watershed Tree (EWT). The operators obtained by using the EWT in the above framework behave like classical morphological operators, but in addition are self-dual. Some application examples are provided: pre-processing for OCR and dust and scratch removal algorithms, and image denoising. We also explore first steps towards obtaining tree transforms that induce a CISL on the image domain as well. 相似文献
93.
Zhen Fang Hassane Assaaoudi Roderick I. L. Guthrie Janusz A. Kozinski Ian S. Butler 《Journal of the American Ceramic Society》2007,90(8):2367-2371
Nanocrystalline tin and indium oxides (In2 O3 /SnO2 ) were synthesized in sub- and supercritical water at 350°/380°C and 30 MPa in <73 s in a tubular flow reactor from an aqueous solution of {SnCl4 +InCl3 } (0.2 M ). The conversion rate for tin was 100%. Nanoparticles were analyzed by transmission electron microscopy (TEM), emitted X-rays, Raman, differential scanning calorimetry, and X-ray diffraction techniques. The bulk particles were composed of In, Sn, and O atoms, and made up of cubic In2 O3 (10 nm) and tetragonal SnO2 (5.5 nm) crystals. After calcination at 500°C for 2 h, little change occurred in the particle size and crystal phase. Traces of tin-doped indium oxide particles were also formed as confirmed by the TEM electron diffraction pattern. Using this one-step, high-temperature hydrothermal process, oxide nanoparticles can be continuously and conveniently produced in a well-controlled process. 相似文献
94.
In the totally anonymous shared memory model of asynchronous distributed computing, processes have no identifiers and run identical programs. Moreover, processes have identical interface to the shared memory, and in particular, there are no single-writer registers. This paper assumes that processes do not fail, and the shared memory consists only of read/write registers, which are initialized to some default value. A complete characterization of the functions and agreement tasks that can be solved in this model is presented. Furthermore, it is shown that if a function is computable, then two registers are sufficient for some algorithm to compute it. Consensus is an important agreement task that can be computed. The paper proves logarithmic lower bounds on the number of registers and rounds needed for solving consensus in this model. A consensus protocol using a linear number of shared registers and rounds is also presented. 相似文献
95.
Mohamed A. Akl Hatem R. Ismael Fathy I. Abd Allah Alla A. Kassem Ahmed M. Samy 《Drug development and industrial pharmacy》2019,45(2):252-264
Tolmetin sodium (TS) is a nonsteroidal anti-inflammatory drug (NSAID) indicated for treatment of musculoskeletal issues. As other NSAID, TS displays a marked side effects on the gastro-intestinal (GI) tract after oral administration. Traditional solid suppositories can cause pain and discomfort for patients, may reach the end of the colon; consequently, the drug can undergo the first-pass effect. TS liquid suppository (TS-LS) was developed to enhance patient compliance and rectal mucosal safety in high-risk patients receiving highly NSAID therapy. This work was conducted to optimize and evaluate Poloxamer P407/P188-based thermoresponsive TS-LS by using mucoadhesive polymers such as methylcellulose (MC). TS-LS was prepared by cold method and characterized their in vitro physicochemical properties as gelation temperature (GT), gel strength, bioadhesive properties, and in vitro release. The safety of the prepared suppository on rectum, stomach, and liver was evaluated histologically. Pharmacokinetic analyses were performed to compare rectal TS-LS to orally Rhumtol® capsules. The results showed that the optimized TS-LS; composed of P407/P188/MC (21/9/0.5% w/w) displayed gelation at rectum temperature ~32.90?°C, gel strength of 21.35?s and rectal retention force at the administration site of 24.25?×?102?dyne/cm2. Moreover, TS-LS did not cause any morphological damage to the rectal tissues. Pharmacokinetic parameters of optimized TS-LS formulation revealed 4.6 fold increase in bioavailability as compared to Rhumtol® capsules. Taken together, the results demonstrated that liquid suppository is a potential and physically safe rectal delivery carrier for improvement rectal bioavailability and in vivo safety of TS. 相似文献
96.
Sudarson S. Sinha Alla Zak Rita Rosentsveig Iddo Pinkas Reshef Tenne Lena Yadgarov 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(4)
Multiwall WS2 nanotubes (and fullerene‐like nanoparticles thereof) are currently synthesized in large amounts, reproducibly. Other than showing interesting mechanical and tribological properties, which offer them a myriad of applications, they are recently shown to exhibit remarkable optical and electrical properties, including quasi‐1D superconductivity, electroluminescence, and a strong bulk photovoltaic effect. Here, it is shown that, using a simple dispersion‐fractionation technique, one can control the diameter of the nanotubes and move from pure excitonic to polaritonic features. While nanotubes of an average diameter >80 nm can support cavity modes and scatter light effectively via a strong coupling mechanism, the extinction of nanotubes with smaller diameter consists of pure absorption. The experimental work is complemented by finite‐difference time‐domain simulations, which shed new light on the cavity mode–exciton interaction in 2D materials. Furthermore, transient absorption experiments of the size‐fractionated nanotubes fully confirm the steady‐state observations. Moreover, it is shown that the tools developed here are useful for size control of the nanotubes, e.g., in manufacturing environment. The tunability of the light–matter interaction of such nanotubes offers them intriguing applications such as polaritonic devices, in photocatalysis, and for multispectral sensors. 相似文献
97.
Alessandro Grillo Maurizio Passacantando Alla Zak Aniello Pelella Antonio Di Bartolomeo 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(35)
This study reports the electrical transport and the field emission properties of individual multi‐walled tungsten disulphide (WS2) nanotubes (NTs) under electron beam irradiation and mechanical stress. Electron beam irradiation is used to reduce the nanotube‐electrode contact resistance by one‐order of magnitude. The field emission capability of single WS2 NTs is investigated, and a field emission current density as high as 600 kA cm?2 is attained with a turn‐on field of ≈ 100 V μm?1 and field‐enhancement factor ≈ 50. Moreover, the electrical behavior of individual WS2 NTs is studied under the application of longitudinal tensile stress. An exponential increase of the nanotube resistivity with tensile strain is demonstrated up to a recorded elongation of 12%, thereby making WS2 NTs suitable for piezoresistive strain sensor applications. 相似文献
98.
Structure formation in the system Li2CO3 Si3N4 both during heating in the powder state (500-1450°C) and also during specimen sintering (1450-1750°C) is studied. The most active formation of binary Li Si nitrides (LiSi2N3, Li2SiN4, Li8SiN4) is observed at 1450-1550°C. With a controlled sintering temperature and the amount of added Li2CO3 it is possible to prepare materials based on silicon nitride with a prescribed phase composition and corresponding properties. 相似文献
99.
In this paper, we present an efficient method based on safe Petri Nets to construct a controller. A set of linear constraints allows forbidding the reachability of specific states. The number of these so-called forbidden states, and consequently the number of constraints, are large and lead to a large number of control places. A systematic method to reduce the size and the number of constraints for safe Petri Nets is offered. By using a method based on Petri Net invariants, maximal permissive controllers are determined. 相似文献
100.
Adjima Bougma Aminata Sere Bazoin Sylvain Raoul Bazie Hassane Sangare Judicaël Thomas Ouilly Imael Henri Nestor Bassole 《Journal of the American Oil Chemists' Society》2021,98(11):1083-1092
Combretum collinum, Combretum micranthum, Combretum nigricans, and Combretum niorense are abundant unconventional seed oils of the African savannah. In this study, the proximate, mineral, amino acid, fatty acid, and triacylglycerol compositions of the four seed oils were quantified, and the oxidative and physicochemical properties were investigated. The amino acid, fatty acid, and triacylglycerol compositions were determined by using high performance liquid chromatography (HPLC) and gas chromatography respectively. Carbohydrates (57.35%–64.20%) followed by crude oils (20.07%–22.60%), proteins (11.95%–15.86%), and ashes (3.78%–6.19%) were the main constituents of the four seed species. The highest ash, crude fat, and protein contents were found in C. collinum, C. nigricans, and C. niorense, respectively. All four seed species were rich in Ca, K and Mg, and poor in methionine, cysteine, and lysine. The four seed oils had high saponification values (198.46–202.71 mgKOH/g), low acidity (1.12–2.26 mg of KOH/g of oil), and peroxide values (1.19–1.98 mEqO2/kg of oil). The seed oils of C. micranthum and C. collinum exhibited the highest thermal oxidative stability (8.10 and 9.79 h at 160°C). Oleic (40.49%–56.69%), palmitic (15.17%–24.27%) and linoleic (9.49%–14.50%) acids were the predominant fatty acids of the four seed oils. The results showed that the four seed species and seed oils had good chemical composition and physicochemical properties making them suitable for food and non-food application. 相似文献