1,720,956 research outputs found
Preparation of a fibre optic sensor based on AgNp/silica composite for pH measurement
Get PDFThe measurement of hydrogen ion concentration in a solution, commonly referred to as pH, holds significant importance in various industries. However, measuring pH under high-temperature and high-pressure (HTHP) conditions has posed a formidable challenge due to the lack of reliable sensors and instrumentation. Recent research has demonstrated the potential of utilising the localised surface plasmon resonance (LSPR) phenomenon seen by gold nanoparticles deposited on optical fibres for pH detection under varying temperature and pressure conditions. Usingthis reported stability of optical fibres in HTHP conditions, this project aimed to create an optical fibre-based pH sensor using silver nanoparticles (AgNp) embedded within a silica matrix, which is suitable for use under HTHP conditions. In this work, a AgNp/silica coating is applied on a glass optical fibre to create an optical pH sensor. The initial stage of the project involved the preparation of colloidal silver nanoparticles and silica gel as separate entities, with a focus on stabilising the colloidal solution and optimising silica gel production. Subsequently, setbacks were overcome in creating the AgNp/silica coating, refining the sol-gel method, and enhancing adhesion through careful adjustments of gelation temperature and heat treatment procedures. The project optimised the gelation process to achieve goodadhesion on the glass while maintaining sufficient silver nanoparticles for pH sensitivity. Characterisation through UV-Vis spectroscopy indicated an extinction peak at 400 nm, which confirms the presence of silver nanoparticles. Afterwards, the AgNp/silica coating was applied to the optical fibres. In the preparation of the optical fibre, the fibre was etched using 7 M sodium hydroxide (NaOH). This marked a successful milestone in utilising NaOH as an etchant for optical fibres. The coated optical fibre reached an ideal core diameter of 104 ± 1 microns, which was required for pH sensitivity. Extensive experimentation led to fine-tuning the sensor setup, ensuring optimal sensitivity while emphasising the delicate balance between light source voltage and detector integration time. Durability testing revealed susceptibility to acidic environments, underscoring theneed for coating improvement. The project explored pH measurement under ambient conditions, demonstrating the sensor's accuracy and stability in various chemical conditions. A calibration curve was constructed, and the coating's reproducibility and repeatability were thoroughly analysed, further validating its reliability as a pH sensing tool. The calibration curve provided insights into pH measurement using theoptical method. Additionally, the performance and sensitivity of the sensor were investigated and compared between sensors prepared in the same batch and those from batch-to-batch production, offering insights into the sensor's characteristics. Furthermore, an evaluation was conducted to assess the accuracy of the sensor in comparison to the potentiometric pH measurement technique. The project's most challenging phase involved testing the sensor in HTHP conditions, revealing issues related to the stability of the AgNp/silica coating at higher temperatures and pressures. It was observed that the pH decreased as the temperature of the solution increased. The experimental apparatus was constructed, which allowed experiments up to a gauge pressure of 5 bar, equivalent to 156 °Ctemperature, where a higher dissolution of the coating was observed. Nonetheless, the sensor was stable at lower gauge pressures, such as 2 bar, even during multiple heating and cooling cycles. Despite these challenges, the inclusion of silver nanoparticles showed promise in improving the sensor's consistency and stability. In conclusion, this project represents a significant effort in developing a robust opticalpH sensor with potential applications in industries such as oil and gas, chemicals, and environmental monitoring. The work underscores the ongoing challenge of maintaining sensor integrity under HTHP conditions, showing the need for further research to enhance coating resilience and a more robust calibration technique. Despite these challenges, this project pushes the boundaries of pH measurement technology and contributes substantially to the field of optical pH sensing. It is an exciting step towards overcoming the limitations of pH measurement in extremeenvironments, opening new avenues for precise monitoring and control in critical industries.The measurement of hydrogen ion concentration in a solution, commonly referred to as pH, holds significant importance in various industries. However, measuring pH under high-temperature and high-pressure (HTHP) conditions has posed a formidable challenge due to the lack of reliable sensors and instrumentation. Recent research has demonstrated the potential of utilising the localised surface plasmon resonance (LSPR) phenomenon seen by gold nanoparticles deposited on optical fibres for pH detection under varying temperature and pressure conditions. Usingthis reported stability of optical fibres in HTHP conditions, this project aimed to create an optical fibre-based pH sensor using silver nanoparticles (AgNp) embedded within a silica matrix, which is suitable for use under HTHP conditions. In this work, a AgNp/silica coating is applied on a glass optical fibre to create an optical pH sensor. The initial stage of the project involved the preparation of colloidal silver nanoparticles and silica gel as separate entities, with a focus on stabilising the colloidal solution and optimising silica gel production. Subsequently, setbacks were overcome in creating the AgNp/silica coating, refining the sol-gel method, and enhancing adhesion through careful adjustments of gelation temperature and heat treatment procedures. The project optimised the gelation process to achieve goodadhesion on the glass while maintaining sufficient silver nanoparticles for pH sensitivity. Characterisation through UV-Vis spectroscopy indicated an extinction peak at 400 nm, which confirms the presence of silver nanoparticles. Afterwards, the AgNp/silica coating was applied to the optical fibres. In the preparation of the optical fibre, the fibre was etched using 7 M sodium hydroxide (NaOH). This marked a successful milestone in utilising NaOH as an etchant for optical fibres. The coated optical fibre reached an ideal core diameter of 104 ± 1 microns, which was required for pH sensitivity. Extensive experimentation led to fine-tuning the sensor setup, ensuring optimal sensitivity while emphasising the delicate balance between light source voltage and detector integration time. Durability testing revealed susceptibility to acidic environments, underscoring theneed for coating improvement. The project explored pH measurement under ambient conditions, demonstrating the sensor's accuracy and stability in various chemical conditions. A calibration curve was constructed, and the coating's reproducibility and repeatability were thoroughly analysed, further validating its reliability as a pH sensing tool. The calibration curve provided insights into pH measurement using theoptical method. Additionally, the performance and sensitivity of the sensor were investigated and compared between sensors prepared in the same batch and those from batch-to-batch production, offering insights into the sensor's characteristics. Furthermore, an evaluation was conducted to assess the accuracy of the sensor in comparison to the potentiometric pH measurement technique. The project's most challenging phase involved testing the sensor in HTHP conditions, revealing issues related to the stability of the AgNp/silica coating at higher temperatures and pressures. It was observed that the pH decreased as the temperature of the solution increased. The experimental apparatus was constructed, which allowed experiments up to a gauge pressure of 5 bar, equivalent to 156 °Ctemperature, where a higher dissolution of the coating was observed. Nonetheless, the sensor was stable at lower gauge pressures, such as 2 bar, even during multiple heating and cooling cycles. Despite these challenges, the inclusion of silver nanoparticles showed promise in improving the sensor's consistency and stability. In conclusion, this project represents a significant effort in developing a robust opticalpH sensor with potential applications in industries such as oil and gas, chemicals, and environmental monitoring. The work underscores the ongoing challenge of maintaining sensor integrity under HTHP conditions, showing the need for further research to enhance coating resilience and a more robust calibration technique. Despite these challenges, this project pushes the boundaries of pH measurement technology and contributes substantially to the field of optical pH sensing. It is an exciting step towards overcoming the limitations of pH measurement in extremeenvironments, opening new avenues for precise monitoring and control in critical industries
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Design and development of an X ray proof operation theater with innovative materials
Get PDFLAUREA SPECIALISTICAIn mediche X-ray applicazioni di imaging, la radiazione è costituito da radiazione primaria e secondaria. Radiazioni primario, chiamato anche fascio utile, è la radiazione emessa direttamente dal tubo a raggi X che viene utilizzata per l'imaging del paziente. Una barriera primaria è un muro, soffitto, pavimento o altra struttura che intercetta la radiazione emessa direttamente dal tubo radiogeno. La sua funzione è di attenuare il fascio utile di opportune schermature obiettivi di progettazione. Radiazione secondaria costituita da raggi X diffusi dagli oggetti paziente e altri come l'hardware e immagini radiazione fuoriuscita del liquido dal alloggiamento del tubo radiogeno. Una barriera secondaria è una parete, soffitto, pavimento o altra struttura che intercettare e attenuano le perdite e radiazioni sparse per l'appropriato obiettivo di progettazione schermatura. Tradizionalmente, è stato utilizzato rivestimenti calcestruzzo o gesso così come portare protetto. Per X-ray camera e sala operatoria ci stiamo dirigendo per il design moderno delle nuove tecnologie che utilizzano pannelli in alluminio a nido d'ape con PVC o strati di HPL. D'ora in avanti sarà considerato un progetto completo di un X-ray Theater per un funzionamento a prova di zona ospedaliera. I pannelli a parete sono stati progettati per essere complanare dotato di orologio, cronometro, tappi di gas, e prese elettriche, griglia d'aria fissata per la ventilazione cabinet, monitor e pc, armadi chirurgia. Il soffitto della sala sarà realizzato con piastrelle a tenuta d'aria completo di struttura portante e comprese le piastrelle di filtro e sistema di illuminazione IP65. Il pavimento sarà di PVC conduttivo in sala operatoria e la preparazione stanza del paziente.
Questo complanare sistema parete offre un facile da pulire superficie e, grazie alla flash per soluzioni di parete, garantisce una perfetta superficie asettico ed una soluzione completa tenuta d'aria: le strutture di supporto sono dotati di guarnizioni a tenuta d'aria ed i pannelli sono sigillate la parte anteriore con il silicio in tinta. Inoltre, il sistema controsoffitto costituito da una sottostruttura metallica per piastrelle in alluminio sospensione e verniciate integrati con luci, tutti sigillati nello stesso modo della parete con doppia protezione. Piastrelle e telai leggeri sono stati progettati espressamente in alluminio per non interferire con i dispositivi a raggi X e sono diverse per sale operatorie e di altri locali ad uso medico (o corridoi).In medical X-ray imaging applications, the radiation consists of primary and secondary radiation. Primary radiation, also called the useful beam, is the radiation emitted directly from the X-ray tube that is used for patient imaging. A primary barrier is a wall, ceiling, floor or other structure that will intercept radiation emitted directly from the X-ray tube. Its function is to attenuate the useful beam to appropriate shielding design goals. Secondary radiation consists of X-rays scattered from the patient and other objects such as the imaging hardware and leakage radiation from the protective housing of the X-ray tube. A secondary barrier is a wall, ceiling, floor or other structure that will intercept and attenuate leakage and scattered radiations to the appropriate shielding design goal. Traditionally, it has been used concrete or gypsum wallboard as well as lead protected. For X-ray room and Operation Theater we are now heading for modern design of new technologies using aluminum honeycomb wall panels with PVC or HPL layers. Hereafter it will be considered a complete design of an X-ray proof Operation Theater for a hospital area. The wall panels are engineered to be equipped with coplanar clock, chronometer, gas plugs, and electric plugs, air grid set for ventilation, monitor and pc cabinet, surgery cabinets. The ceiling of the room will be made of air tight tiles complete with supporting structure and including filter tiles and IP65 lighting system. The floor will be of PVC conductive in the operating theatre and patient preparation room.
This co-planar wall system offers an easy to be cleaned surface and, thanks to the flash to wall solutions, guarantees a perfect aseptic surface and a complete air tight solution: the supporting structures are equipped with air tight gaskets and the panels are sealed from the front with silicon in matching color. In addition, the false ceiling system consists of a metal substructure for suspension and powder coated aluminum tiles integrated with lights, all sealed in the same way of the wall with double protection. Tiles and light frames are designed expressly in aluminum not to interfere with the X-ray devices and are different for operating theatres and other medical rooms (or corridors)
Variations on the Author
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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