1,720,979 research outputs found
A hybrid electrochemical-colorimetric sensing platform for detection of explosives
Full text linkA highly selective, sensitive, and low-cost hybrid sensing platform is developed based on extraordinary properties of explosives in an ionic liquid and an integrated electrochemical and colorimetric approach.Fil: Forzani, Erica S.. Arizona State University; Estados UnidosFil: Lu, Donglai. Arizona State University; Estados UnidosFil: Leright, Matthew J.. Arizona State University; Estados UnidosFil: Aguilar, Alvaro Diaz. Arizona State University; Estados UnidosFil: Tsow, Francis. Arizona State University; Estados UnidosFil: Iglesias, Rodrigo Alejandro. Arizona State University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Zhang, Qian. Tsingha University; ChinaFil: Lu, Jin. Arizona State University; Estados Unidos. Tsingha University; ChinaFil: Li, Jinghong. Tsingha University; ChinaFil: Tao, Nongjian. Arizona State University; Estados Unido
A personal device for analyzing carbon dioxide in real time and real breath: experimental investigation and computational simulation
No full textThe analysis of breath CO2 provides valuable information of pulmonary and cardiovascular functions, and plays a crucial role in monitoring patients with respiratory problems. Developing portable sensors for real breath CO2 analysis has been challenging because exhaled breath is hot, humid and turbulent. In this work, we have developed, modeled and tested a portable CO2 sensor that can analyze end tidal CO2 concentration in breath and in real time accurately. The key components of the sensor comprise a fluidic system for efficient breath sample delivery and a colorimetric detection integrated into the fluidic system. The modeling includes turbulent mass transport, heat transfer from the samples at body temperature to the device environment, and chemical reaction mechanisms, including multiple reactions pathways and diffusion of CO2 in the sensing layer. Furthermore, the sensor has been tested and compared with a standard commercial CO2 analyzer, and the results are in good agreement with those of the commercial analyzer, and with the modeling.Fil: Zhao, Di. Arizona State University; Estados UnidosFil: Miller, Dylan. Arizona State University; Estados UnidosFil: Shao, Dangdang. Arizona State University; Estados UnidosFil: Xian, Xiaojun. Arizona State University; Estados UnidosFil: Tsow, Francis. Arizona State University; Estados UnidosFil: Iglesias, Rodrigo Alejandro. Arizona State University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Forzani, Erica S.. Arizona State University; Estados Unido
Hybrid separation and detection device for analysis of benzene, toluene, ethylbenzene, and xylenes in complex samples
Full text linkWe present a hybrid system for rapid detection and analysis of benzene, toluene, ethylbenzene, and xylenes (BTEX). The system combines selective and sensitive sensing elements with a fast and miniaturized chromatographic separation method. The sensing elements are an array of microfabricated quartz crystal tuning forks modified with selective molecularly imprinted polymers, and the separation method uses optimized short columns. The high sensitivity and selectivity of the sensing elements together with the help of the separation provides fast detection and analysis of BTEX in real samples containing highly concentrated interfering agents without preconcentration or heating of columns. The low cost, low power consumption, and small size of the hybrid device are particularly suitable for occupational health, industrial safety, and epidemiological applications.Fil: Iglesias, Rodrigo Alejandro. Arizona State University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Tsow, Francis. Arizona State University; Estados UnidosFil: Wang, Rui. Arizona State University; Estados UnidosFil: Forzani, Erica S.. Arizona State University; Estados UnidosFil: Tao, Nongjian. Arizona State University; Estados Unido
Ultrasensitive Detection of Nitrogen Oxides over a Nanoporous Membrane
Full text linkA nitrogen oxide (NOx; x = 1, 2) optical sensor with an extremely low detection limit in the range of fractions of ppbV (0.3 ppbV for 20 s sample injection) is presented. Phenylenediamine derivatives are utilized as molecular probes in the solid state on a nanoporous membrane to produce a miniaturized and low cost sensing platform for use as a wearable personal monitor.Fil: Prabhakar, Amlendu. Arizona State University; Estados UnidosFil: Iglesias, Rodrigo Alejandro. Arizona State University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Wang, Rui. Arizona State University; Estados UnidosFil: Tsow, Francis. Arizona State University; Estados UnidosFil: Forzani, Erica S.. Arizona State University; Estados UnidosFil: Tao, Nongjian. Arizona State University; Estados Unido
A hybrid nanosensor for TNT vapor detection
Full text linkReal-time detection of trace chemicals, such as explosives, in a complex environment containing various interferents has been a difficult challenge. We describe here a hybrid nanosensor based on the electrochemical reduction of TNT and the interaction of the reduction products with conducting polymer nanojunctions in an ionic liquid. The sensor simultaneously measures the electrochemical current from the reduction of TNT and the conductance change of the polymer nanojunction caused from the reduction product. The hybrid detection mechanism, together with the unique selective preconcentration capability of the ionic liquid, provides a selective, fast, and sensitive detection of TNT. The sensor, in its current form, is capable of detecting parts-per-trillion level TNT in the presence of various interferents within a few minutes.Fil: Aguilar, Alvaro Díaz. Arizona State University; Estados UnidosFil: Forzani, Erica S.. Arizona State University; Estados UnidosFil: Leright, Mathew. Arizona State University; Estados UnidosFil: Tsow, Francis. Arizona State University; Estados UnidosFil: Cagan, Avi. Arizona State University; Estados UnidosFil: Iglesias, Rodrigo Alejandro. Arizona State University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Nagahara, Larry A.. Motorola Laboratories; Estados UnidosFil: Amlani, Islamshah. Motorola Laboratories; Estados UnidosFil: Tsui, Raymond. Motorola Laboratories; Estados UnidosFil: Tao, N.J.. Arizona State University; Estados Unido
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
A new sensor for the assessment of personal exposure to volatile organic compounds
Full text linkTo improve our understanding of indoor and outdoor personal exposures to common environmental toxicants released into the environment, new technologies that can monitor and quantify the toxicants anytime anywhere are needed. This paper presents a wearable sensor to provide such capabilities. The sensor can communicate with a common smart phone and provides accurate measurement of volatile organic compound concentration at a personal level in real-time, providing environmental toxicants data every three minutes. The sensor has high specificity and sensitivity to aromatic, alkyl, and chlorinated hydrocarbons with a resolution as low as 4 parts-per-billion (ppb), with a detection range of 4 ppb-1000 ppm (parts-per-million). The sensor's performance was validated using Gas Chromatography and Selected Ion Flow Tube - Mass Spectrometry reference methods in a variety of environments and activities with overall accuracy higher than 81% (r 2 > 0.9). Field tests examined personal exposure in various scenarios including: indoor and outdoor environments, traffic exposure in different cities which vary from 0 to 50 ppmC (part-per-million carbon from hydrocarbons), and pollutants near the 2010 Deepwater Horizon's oil spill. These field tests not only validated the performance but also demonstrated unprecedented high temporal and spatial toxicant information provided by the new technology. © 2012 Elsevier Ltd.Fil: Chen, Cheng. Arizona State University; Estados UnidosFil: Driggs Campbell, Katherine. Arizona State University; Estados UnidosFil: Negi, Indira. Arizona State University; Estados UnidosFil: Iglesias, Rodrigo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Arizona State University; Estados UnidosFil: Owens, Patrick. Shell Oil Products US; Estados UnidosFil: Tao, Nongjian. Arizona State University; Estados UnidosFil: Tsow, Francis. Arizona State University; Estados UnidosFil: Forzani, Erica S.. Arizona State University; Estados Unido
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