1,720,967 research outputs found
Eco-friendly mangrove-derived nanocomposite coating for sustainable biofouling and corrosion protection in Persian Gulf field trials
Full text link: Marine biofouling and corrosion impose major environmental and operational costs on maritime industries. This study aims to develop an eco-friendly, mangrove-derived nanocomposite coating that sustainably mitigates both challenges. Aluminum oxide and titanium dioxide nanoparticles were green-synthesized using Avicennia marina leaf extract and integrated with multi-walled carbon nanotubes (MWCNTs) into a polydimethylsiloxane (PDMS) matrix. Structural characterization (XRD, FTIR, FESEM-EDS, UV-Vis) confirmed uniform nanoparticle dispersion and hybrid formation with enhanced photocatalytic efficiency. The optimized 0.5 wt% Al2O3-TiO2@MWCNT/PDMS coating exhibited superior antibacterial performance, achieving 96.5 % inhibition against S. aureus, 97.2 % against E. coli, and 95.8 % against P. aeruginosa, alongside 98.7 % anti-algal suppression of Nannochloropsis oculata. Corrosion current density reached as low as 0.008 μA/cm2, while polarization resistance increased to 4750 kΩ·cm2. Four-month field trials in the Persian Gulf demonstrated a 68 % reduction in fouling coverage relative to control PDMS panels. Through green synthesis and the exclusion of toxic biocides, this coating minimizes ecological risk and supports UN Sustainable Development Goals 9 and 14 by providing a scalable, durable, low-impact solution for marine infrastructure protection
Nano-organic supports for enzyme immobilization: Scopes and perspectives
No full textA variety of organic nanomaterials and organic polymers are used for enzyme immobilization to increase enzymes stability and reusability. In this study, the effects of the immobilization of enzymes on organic and organic-inorganic hybrid nano-supports are compared. Immobilization of enzymes on organic support nanomaterials was reported to significantly improve thermal, pH and storage stability, acting also as a protection against metal ions inhibitory effects. In particular, the effects of enzyme immobilization on reusability, physical, kinetic and thermodynamic parameters were considered. Due to their biocompatibility with low health risks, organic support nanomaterials represent a good choice for the immobilization of enzymes. Organic nanomaterials, and especially organic-inorganic hybrids, can significantly improve the kinetic and thermodynamic parameters of immobilized enzymes compared to macroscopic supports. Moreover, organic nanomaterials are more environment friendly for medical applications, such as prodrug carriers and biosensors. Overall, organic hybrid nanomaterials are receiving increasing attention as novel nano-supports for enzyme immobilization and will be used extensively
Novel cold-adapted lipase from Psychrobacter sp. C18 immobilized on reduced graphene oxide-cellulose nanomatrix with high activity and stability
No full textHere, biocompatible hybrid graphene oxide-cellulose nanocrystals (rGO-CNC) were synthesized and used as nanomatrix to immobilize a novel recombinant cold-adopted lipase from Psychrobacter sp. C18. Different steps of the nanomatrix synthesis and the lipase immobilization were verified by FT-IR, DLS, SEM, circular dichroism, spectrofluorimetry, and spectrophotometer-based kinetic and thermodynamic studies. According to our results, the values of kcat for physically and covalently immobilized lipase were 1.06 and 2.47 times higher than that of the soluble lipase, respectively. Moreover, the remaining activity of lipases during storage stability at 4 °C for 30 days were estimated to be 2.47 and 1.25 more than that of the soluble lipase, respectively. In addition, covalently immobilized lipases were reused after 5 successive cycles while retained about 60 % of its initial activity. Although the physical adsorption strategy increased the catalytic efficiency by 2.45 times, compared with soluble lipase, the thermal stability of covalently immobilized lipase was 5.2 times higher than that of the soluble enzyme. Additionally, covalently immobilized lipase showed remarkable resistance against extreme changes in environmental conditions such as metal ions, organic solvents, and pH changes. Altogether, based on our results, the covalently immobilized novel cold-adopted lipase is a suitable candidate for biotechnological and industrial applications
Identification of a novel tailor-made chitinase from white shrimp Fenneropenaeus merguiensis
No full textFenneropenaeus merguiensis (commonly named banana shrimp) is one of the most important farmed crustacean worldwide species for the fisheries and aquaculture industry. Besides its nutritional value, it is a good source of chitinase, an enzyme with excellent biological and catalytic properties for many industrial applications. In the present study, a putative chitinase-encoding cDNA was synthesized from mRNA from F. merguiensis hepatopancreas tissue. Subsequently, the corresponding cDNA was cloned, sequenced and functionally expressed in Escherichia coli, and the recombinant F. merguiensis chitinase (rFmCHI) was purified by His-tag affinity chromatography. The bioinformatics analysis of aminoacid sequence of rFmCHI displayed a cannonical multidomain architecture in chitinases which belongs to glycoside hydrolase family 18 (GH18 chitinase). Biochemical characterization revealed rFmCHI as a monomeric enzyme of molecular weight 52 kDa with maximum activity at 40 °C and pH 6.0 Moreover, the recombinant enzyme is also stable up to 60 °C, and in the pH range 5.0-8.0. Steady-state kinetic studies for colloidal chitin revealed KM, Vmax and kcat values of 78.18 μM, 0.07261 μM. min−1 and 43.37 s−1, respectively. Overall, our results aim to demonstrate the potential of rFmCHI as suitable catalyst for bioconversion of chitin waste.Sin financiación5.999 Q1 JCR 20210.882 Q1 SJR 2021No data IDR 2021UE
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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