1,720,956 research outputs found
Biocompatible and antibacterial silver tantalum oxide thin film by magnetron sputtering for surgical applications / Rodianah Alias
No full textStainless steel (SS) is used extensively for healthcare, hygiene and surgical applications due to its excellent corrosion resistance and adequate mechanical strength. SS grade 316L is the most widely employed stainless steel owing to the high corrosion resistance, good mechanical properties, resistance to sensitization and ease of fabrication. Nonetheless, stainless steel lacks antibacterial activity. To incorporate the antimicrobial characteristic in SS 316L-based surgical instruments, a new nanocomposite thin film coating comprising silver (Ag) and tantalum oxide (Ta2O5) was deposited by physical vapor deposition (PVD) reactive magnetron sputtering in this research. The delamination of the ceramic layers on the SS 316L substrate is one of the major limitations arising from insufficient crystallization and poor adhesion strength. It was found that the adhesion strength improved in a precisely controlled thermal treatment process. The microstructure, morphology, phases, elemental, structure, micromechanical properties, surface chemistry, hydrophobicity, toxicity and antibacterial performance of the as-deposited and annealed thin film specimens were analyzed to determine the characteristics of the developed layers. The thermal treatment setup involved temperatures of 250 to 850 °C that progressively increased the crystallinity and segregation of Ag at the surface. The highest adhesion strength was achieved when the coated samples were annealed at 400 °C, with 154 % improvement achieved compared to the as-deposited layer. The samples annealed at 400 °C demonstrated excellent antibacterial performance against gram-negative Escherichia coli (ATCC 15597) and gram-positive Staphylococcus aureus (NCTC 6571) according to inhibition zone measurements. Ag/Ag-Ta2O5 prepared at 400 °C exhibited significantly superior biocompatibility (cell attachment and proliferation of seeded human bone marrow-derived mesenchymal stromal cells) compared to Ag/Ag-Ta2O5 annealed at 700 °C as well as SS 316L
The effect of substrate and enzyme concentration to the fructooligosaccharides (FOS) production
Get PDFThe fructooligosaccharides (FOS) are oligosaccharides of fructose that have simple molecule. They can produced by action of fructosyltransferase with sucrose. The fructooligosaccharides is significant to the diabetec and colon disease due to its function reducing the content of sugar in blood. FOS also has a function of prebiotic whereas capable help in human digestion colon. The purpose of this research to determine the effect of substrate and enzyme and the optimum both two of these factor to produce FOS The experiment is carried out used 40 to 80% (w/v) of sucrose concentration and 5% to 9% (w/v) of enzyme concentration in water bath at temperature of 60 °C at 100 rpm. The samples were analyzed by using HPLC, UV-Vis, and TOC to determine FOS concentration, sucrose residual and TOC content respectively. The Design Expert Software also involve to determine the optimum substrate and enzyme to produce FOS. From the result acquire, Increased 40 to 60% of sucrose concentration resulted in increased 96% FOS production and constant after 60% of sucrose concentration approximately at 258 mg/ml. As increasing of enzyme concentration, the production of FOS also increase up to the maximum point of 241 mg/ml FOS production at 5% to 7% enzyme concentration and decrease after 7% enzyme concentration to 134 mg/ml. By using Design Expert Software, increased of sucrose concentration, the FOS production also increase. Increased of enzyme concentration, the FOS production also increase. The optimum condition of substrate and enzyme concentration is 50% and 7% to produce 552.857 mg/ml concentration of FOS. -Author
An Inexpensive & Safe Method for Preparation of Caryophyllene Oxide
Get PDFCaryophyllene oxide which exists as white crystalline solids with melting points of 62 °C, is widely used as an important material in perfumery industry and recently had been patented as antitumor agent. This 99% pure oxide compound is very muchmore expensive than the original caryophyllene due to the difficulty in production. Experiments were carried out to produce caryophyllene oxide by using inexpensive and safe method. In this study, four objectives were studied; extraction, separation, purification of caryophyllene from clove buds which were later used in this synthesis of caryophyllene oxide in this study. In extraction, four methods were used, cleaner- ultrasonic, hydrodistillation, steam distillation and microwave to obtain clove oil and found that, hydro distillation method was found to give the highest yield of clove oil. For separation process the cayophyllene and the other non-polar molecules in clove oil were separated from eugenol, the highest yield for both clove bud and clove leaf were achieved at a ratio of clove oil: sodium hydroxide of 1: 2. Purification of caryophyllene by using vacuum distillation consist 94% component of a mixture of caryophyllene, and 5.8% alpha-cubebene by using GC/MS analyzer at 136 °C. Caryophyllene oxide was then synthesized by using four different acids, formic acid, acetic anhydride, 3-chloroperbenzoic acid, and acetic acid. The highest percentage of caryophyllene oxide formed in solution analysed by GC/MS was by formic acid (86.47%), followed by 3-chloroperbenzoic acid (81.47%), acetic anhydride (77.04%), and acetic acid (75.33%). Caryophyllene oxide was then crystallized at low temperature until subsequent analysis showed that it is 99% pure
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
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
Enhancement of as-sputtered silver-tantalum oxide thin film coating on biomaterial stainless steel by surface thermal treatment
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