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141.
de Jesus CG dos Santos V Canestraro CD Zucolotto V Fujiwara ST Gushikem Y Wohnrath K Pessoa CA 《Journal of nanoscience and nanotechnology》2011,11(4):3499-3508
Nanostructured films comprising a 3-n-propylpyridinium silsesquioxane polymer (designated as SiPy+Cl-) and copper (II) tetrasulfophthalocyanine (CuTsPc) were produced using the Layer-by-Layer technique (LbL). To our knowledge this is the first report on the use of silsesquioxane derivative polymers as building blocks for nanostructured thin films fabrication. Deposition of the multilayers were monitored by UV-Vis spectroscopy revealing the linear increment in the absorbance of the Q-band from CuTsPc at 617 nm with the number of SiPy+Cl-/CuTsPc or CuTsPc/SiPy+Cl-bilayers. FTIR analyses showed that specific interactions between SiPy+Cl- and CuTsPc occurred between SO3- groups of tetrasulfophthalocyanine and the pyridinium groups of the polycation. Morphological studies were carried out using the AFM technique, which showed that the roughness and thickness of the films increase with the number of bilayers. The films displayed electroactivity and were employed to detection of dopamine (DA) and ascorbic acid (AA) using cyclic voltammetry, at concentrations ranging from 1.96 x 10(-4) to 1.31 x 10(-3) molL(-1). The number and the sequence of bilayers deposition influenced the electrochemical response in presence of DA and AA. Using differential pulse technique, films comprising SiPy+/-/CuTsPc were able to distinguish between DA and ascorbic acid (AA), with a potential difference of approximately with 500 mV, in the concentration range of 9.0 x 10(-5) to 2.0 x 10(-4) molL(-1), in pH 3.0. 相似文献
142.
143.
Collins Acheampong Liping Zhang Christiana Agbo Dong Liang Changsen Du Shaohai Fu 《Journal of surfactants and detergents》2019,22(4):885-895
An acid-catalyzed esterification method was employed to synthesize five A-B-A-type nonionic dimeric surfactants (XOP-3, XOP-4, XOP-6, XOP-9, and XOP-10) comprising of octyl phenyl ether (OP-10) and a homologous series of α, ω-dicarboxylic acids (C3, C4, C6, C9, and C10) as the spacer molecules. The various surfactants produced were characterized based on Fourier transform infrared (FT-IR) spectroscopy, mass spectra (MS), and 1H NMR spectra. The newly synthesized series of surfactants were used for the dispersion of Hostaperm Pink E (Pigment Red 122) in an ultrasonic disruptor. Based on the selected pigment, the interfacial, colloidal, and rheological properties of the pigment dispersion were examined. The dispersion performances and properties of the surfactants produced differed based on the number of carbon atoms in hydrocarbon chains of the various spacer molecules. Due to this, surfactants created with short to moderate hydrocarbon chain spacer molecules exhibited a better dispersion performance than that of surfactants created with long hydrocarbon chain spacer molecules. The calculated cross-sectional area values of the various surfactants synthesized confirmed their differences in dispersion performance and properties. 相似文献
144.
In an era increasingly focused on the question of how to value fresh water, this essay argues that questions of value cannot be parsed apart from the multiple ontologies that undergird those value judgments. Returning to Nelson's observation that water exists “in a metaphysical blindspot,” this essay describes what chastened metaphysics have to do with fresh waters' pluralities and depicts three apertures by which contemporary water discourses delineate fresh waters' values: economic theory and neoliberal market practice, paradigms of liberal governance, and cultural‐religious multiplicities. In the latter, fresh waters' life‐giving properties tend to be accorded central respect in ways that often exceed the ontological understandings and moral possibilities preferred by western liberal discourses in an era that has been decisively shaped by scientific, hydraulic/extractive modernity and rational planning. Parsing the ways that selected cultural‐religious formulations align with or challenge dominant governance paradigms, this essay argues that decolonial ways of proceeding are necessary if value discourse and ethical action are to be substantially oriented toward the inclusive, long‐term flourishing of human and other bodies of waters. The final section summarizes these claims and underscores necessary warnings. This article is categorized under:
- Human Water > Value of Water
- Human Water > Water as Imagined and Represented
- Human Water > Methods
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146.
Som N. Dahal Stephen P. Bremner Christiana B. Honsberg 《Progress in Photovoltaics: Research and Applications》2010,18(4):233-239
Heterostructures that include self‐assembled quantum dots (SAQDs) have been suggested as model systems for the realization of novel high efficiency solar cells such as those based on intermediate bands (IBs). The lattice mismatch in the epitaxial growth of these structures, necessary for the formation of SAQDs, introduces strain throughout the structure, making the selection of materials systems with appropriate physical parameters problematic. The model solid theory is used to calculate the energy band edge alignment at Γ point of such quantum dot (QD) heterostructures including the effects of strain. With the modified band gaps due to strain, a materials search was performed for high efficiency QD solar cells among III‐V binaries and ternaries with negligible valence band offsets. This requirement of the valence band offset along with the limited band gap ranges for optimum efficiency results in only a few feasible materials systems being identified. The optimum barrier/dot material system found was Al0.57In0.43As/InP0.87Sb0.13 grown on lattice matched metamorphic buffer layer, but due to miscibility gap concerns it is suggested that the Al0.50In0.50As/InAs0.41P0.59 fully strained system may be preferred. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
147.
A discourse on water ethics has emerged as a field linking practical water demands, social practices, and hydrological constraints to philosophic norms. The field arose parallel to growing, global understandings of the interconnected nature of water management and governance challenges. As such, it has been inflected with issues and contests across a range of policy concerns—from holistic and integrated water management to economics, justice, and human rights. The emerging water ethics discourse challenges both traditional environmental ethics and conventional approaches to resource management on issues of gender, power relations, and ecological concerns. It suggests an alternate, place‐specific approach for linking shared water concerns to normative contests. WIREs Water 2014, 1:533–547. doi: 10.1002/wat2.1043 This article is categorized under:
- Human Water > Rights to Water
- Human Water > Value of Water
- Human Water > Water Governance
148.
Ademola Olusola Adesina Patrick Seun Ayobioloja Ibidun Christiana Obagbuwa Tola John Odule Adenrele A. Afolorunso Sunday Adeola Ajagbe 《计算机、材料和连续体（英文）》2023,74(2):2661-2675
CAPTCHA is an acronym that stands for Completely Automated Public Turing Test to tell Computers and Humans Apart (CAPTCHA), it is a good example of an authentication system that can be used to determine the true identity of any user. It serves as a security measure to prevent an attack caused by web bots (automatic programs) during an online transaction. It can come as text-based or image-based depending on the project and the programmer. The usability and robustness, as well as level of security, provided each of the varies and call for the development of an improved system. Hence, this paper studied and improved two different CAPTCHA systems (the text-based CAPTCHA and image-based CAPTCHA). The text-based and image-based CAPTCHA were designed using JavaScript. Response time and solving time are the two metrics used to determine the effectiveness and efficiency of the two CAPTCHA systems. The inclusion of response time and solving time improved the shortfall of the usability and robustness of the existing system. The developed system was tested using 200 students from the Federal College of Animal Health and Production Technology. The results of each of the participants, for the two CAPTCHAs, were extracted from the database and subjected to analysis using SPSS. The result shows that text-based CAPTCHA has the lowest average solving time (21.3333 s) with a 47.8% success rate while image-based CAPTCHA has the highest average solving time was 23.5138 s with a 52.8% success rate. The average response time for the image-based CAPTCHA was 2.1855 s with a 37.9% success rate lower than the text-based CAPTCHA response time (3.5561 s) with a 62.1% success rate. This indicates that the text-based CAPTCHA is more effective in terms of usability tests while image-based CAPTCHA is more efficient in terms of system responsiveness and recommended for potential users. 相似文献
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