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61.
Summary A functional model is proposed to account for the evolution of linear thermoviscoelastic media. By suitably modelling the fading memory of the medium, several quantities associated with this memory are defined, particularly under cyclic loading. Comparisons are made between this model and various existing thermomechanical constitutive equations: The assumptions implicitly involved in the latter are explicitly stated and the reservations they call for are discussed in the light of experimental data. 相似文献
62.
Nano‐crystalline cellulose,chemical blowing agent,and mold temperature effect on morphological,physical/mechanical properties of polypropylene 下载免费PDF全文
Polypropylene (PP)/nano‐crystalline cellulose (NCC) composites and foams were produced through extrusion compounding combined with injection molding. From the samples produced, a complete morphological, physical, and mechanical analysis was performed to study the effect of NCC concentration (0–5wt %), foaming agent content (0 to 2wt %) and mold temperature (30°C and 80°C). NCC was very effective to reduce cell size (42–71%) and increase cell density (5–37 times) of the foams, while slightly increasing the overall density (2–7%). The results showed that NCC addition increased the specific tensile modulus (15–22%), specific tensile strength (1–14%) and specific flexural modulus (13–26%) of PP, but decreased specific impact strength (10–20%) and specific elongation at break (50–96%). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42845. 相似文献
63.
The objectives of this study were to determine phenolic content and antioxidant activity of methanolic extracts from different parts of cantaloupe (leaf, stem, skin, seed and flesh). The flesh extract afforded the highest yield (89.6 ± 0.3%) whilst the lowest yield was obtained from the seed (13.7 ± 0.5%) (p < 0.05). The leaf extract showed the highest total phenolic content (26.4 ± 0.3 mg GAE/g extract) and total flavonoid content (69.7 ± 3.37 μg RE/g extract) accompanied with best antioxidant activity through all antioxidant assays (p < 0.05). In addition, the stem extract also exhibited good antioxidant activity. Thus, these results suggest that methanolic extracts of cantaloupe leaf and stem may serve as a potential source of natural antioxidant for food and nutraceutical application. 相似文献
64.
By their widespread availability and dissemination through open access media, scholarly outputs witness an improved visibility
supposed to cause a better citation performance. However, due to the existence of the Matthew effect in science system, which
affects users’ perceptions of quality, ultimate effects of the enhanced visibility on different entities are obscure. Moreover,
different attitudes towards open access give rise to a more strong quality dynamics in the open access world. Aiming to explore
the consequence of the interaction between visibility and quality dynamics, this study investigates countries positioning
in open access journals. The results show that the world’s countries welcome open access pattern whether by submitting to
or publishing open access journals. A large proportion of the enduring, prestigious open access journals are published by
scientifically proficient and developing nations, emphasizing their successful commitment to maintain the undertaken role.
The results of the citation analysis highlight national inequalities regarding citation distributions among countries contributing
to the journals within the system and within individual disciplines in the system. Well-performing countries mainly consist
of advanced ones; however, some lessdeveloped nations are found to perform well in the journal system. 相似文献
65.
Open Access movement has been proven to be capable to enhance the recognition of scientific outputs by improving their visibility.
However, it is not clear how different entities benefit from the Open Access advantage; because, the recognition process is
dominated by some psychological or realistic biases, resulting in an unequal distribution of citations between different entities.
The biases may be exacerbated in Open Access world, e.g. due to the scientists uncertainty about the quality of Open Access
materials, or quantitatively or qualitatively unequal presence of countries. Consequently, although, Open Access is able to
achieve their potential citations, it is not unlikely that it increases the inequalities, depriving the already “have-nots”.
Trying to illuminate how countries are benefiting from Open Access advantage, this study compares citation performances of
the world’s countries in two journal sets, i.e. Open Access and non Open Access journals. The results of the analyses conducted
at subject field level show that overall recognition gap between developed and less-developed blocks is widened by publishing
in Open Access journals. The verification of individual countries’ performances confirms the finding by revealing that open-access-advantaged
nations are mainly consisted of developed ones. However, some open-access-advantaged instances are from the less-developed
block, which may promisingly suggest early heralds of Open Access potentialities to achieve the recognition of “lost sciences”,
leading to relative reparation of the gap in future. 相似文献
66.
This study aimed to assess the quality of road runoff in heavy traffic and residential areas of Hamedan province, in the western region of Iran. To investigate the effects of salt pollution, 14 runoff samples were collected from streets during the winter and spring of 2009. Streets received different amounts of deicing salt depending on the traffic density. Results showed that deicing salt has major affects on sodium (Na+), calcium (Ca2+), magnesium (Mg2+), chloride (Cl?), bicarbonate (), sulfate () and phosphate () pollution. This is important because this type of watercourse contamination can lead to serious problems, such as eutrophication. We also found an increase in lead (Pb2+) concentration, which was not attributable to the application of deicing agents, but that was due to the combustion of leaded gasoline. Speciation of Ca, Mg, Pb and P chemical species in the samples was calculated using Visual Minteq 2.6 program. The results indicated that Ca and Mg were mainly present as free ions, Pb was mainly present as PbCO3 (aq), while the dominant P species were and . 相似文献
67.
Balakrishnan Vimala Lok Pik Yin Abdul Rahim Hajar 《The Journal of supercomputing》2021,77(4):3795-3810
The Journal of Supercomputing - This paper investigates the sentiment and emotion of digital payment application consumers using a hybrid approach consisting of both supervised and unsupervised... 相似文献
68.
Comparative and competitive adsorption of cadmium, copper, nickel, and lead ions by Iranian natural zeolite 总被引:4,自引:0,他引:4
The competitive adsorption behavior of cadmium (Cd2+), copper (Cu2+), nickel (Ni2+), and lead (Pb2+) ions using Iranian natural zeolite has been studied in order to determine its applicability in treating industrial wastewater. Tests to determine both the rate of adsorption and the uptake at equilibrium were performed under batch conditions from single- and multi-component solutions. The optimum conditions for the treatment process were investigated by observing the influence of pH levels, the presence of competing ions, varying the mass of zeolite and different contact time. Adsorption kinetics of the zeolite followed first-order kinetics, showing about 100 % of Pb2+ removal within 40 min and reaching an equilibrium state within 24 h for Cd2+, Cu2+, and Ni2+. The results indicated that removal of metals from single- and multi-component solutions is best described by a Freundlich isotherm, in which the distribution coefficient was in the following order: Pb2+ > Cu2+ > Cd2+ > Ni2+. In the multi-component solutions, metals exhibit competitive adsorption on the zeolite. The adsorption is reduced to 90, 53, 30, and 22 % of single component of Cu2+, Ni2+, Cd2+, and Pb2+, respectively. However, the total adsorption was higher than single component. Finally, soil solution saturation indices and speciation of metals was assessed using Visual MINTEQ 2.6 software, and probability of precipitation of minerals supported by scanning electron microscopy. The research indicates that Cd2+ and Ni2+ retention by zeolite can be viewed as the result of ion exchange reaction, but Pb2+ and Cu2+ retention is both due to ion exchange and precipitation. These results show that Iranian natural zeolite particularly effective in removing cationic heavy metal species from industrial wastewater. 相似文献
69.
Recently, researchers succeeded in designing and manufacturing a new class of nanoparticles (NPs) called hybrid NPs. Among hybrid NPs, bimetallic and core–shell NPs were a revolutionary step in NPs science. A large number of green physiochemical and methods for nanostructures synthesis have been published. Eventually, physiochemical methods are either expensive or require the use of chemical compounds for the synthesis of bimetallic and core–shell nanostructures. The main challenges that scientists are facing are making the process cheaper, facile and eco‐friendly efficient synthesis process. Green synthesis (biosynthesis) refers to the use of bio‐resources (such as bacteria, fungi, plants or their derivatives) for the synthesis of nanostructures. The popularity of the green synthesis of nanostructures is due to their environmental friendliness and no usage of toxic materials, environmental friendliness for the synthesis or stability of nanostructure. Bimetallic and core–shell NPs have many biomedical applications such as removing heavy metals, parasitology, molecular and microbial sensor, gene carrier, single bacterial detection, oligonucleotide detection and so on. The purpose of this study is to discuss briefly the biosynthesised bimetallic and core–shell NPs, their biomedical applications.Inspec keywords: nanofabrication, nanoparticles, biosensors, microorganisms, molecular biophysics, nanobiotechnologyOther keywords: biosynthesised bimetallic –shell, environmental friendliness, green synthesis, eco‐friendly efficient synthesis process, core–shell nanostructures, bimetallic –shell nanostructures, physiochemical methods, nanostructures synthesis, green physiochemical, NPs science, hybrid NPs, biomedical applications, core–shell nanoparticles, bimetallic –shell nanoparticles, biosynthesis 相似文献
70.
Ali A. Ensafi Hajar Bahrami B. Rezaei Hassan Karimi-Maleh 《Materials science & engineering. C, Materials for biological applications》2013,33(2):831-835
An ionic liquid–TiO2 nanoparticle modified carbon paste electrode (IL–TiO2/CPE) was used as a fast and sensitive tool for the investigation of the electrochemical oxidation of benserazide using voltammetry. This modified electrode has been fabricated using hydrophilic ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate) as a binder. The modified electrode offers a considerable improvement in voltammetric sensitivity toward benserazide, compared to the bare electrode. Using differential pulse voltammetry (DPV), the electrocatalytic oxidation peak current of benserazide shows a linear calibration curve in the range of 1.0–600 μmol L? 1 benserazide. The limit of detection was equal to 0.4 μmol L? 1. The relative standard deviation (RSD%) for eight successive assays of 10 μmol L? 1 benserazide was 1.1%. Finally, the proposed method was successfully applied to the determination of benserazide in real samples such as blood serum and urine. 相似文献