1,727,751 research outputs found
Laboratory investigation on chemo-rheological and mechanical properties of bio-asphalt materials for sustainable asphalt pavements
Get PDFAl giorno d'oggi, uno dei principali interessi della società moderna è quello di sostituire quantità sempre maggiori di prodotti derivati dal petrolio, che è una fonte non rinnovabile in progressivo esaurimento. Negli ultimi decenni, l'uso di biomateriali ha acquisito un notevole interesse nel settore dell'ingegneria civile. In questo contesto, l'industria stradale è interessata a sviluppare nuove soluzioni "verdi", promuovendo i principi della sostenibilità e dell'economia circolare. Infatti, data la rapida crescita delle città e dei volumi di traffico, la domanda di materie prime per la costruzione e la manutenzione delle pavimentazioni è aumentata drasticamente, insieme al loro prezzo. Allo stesso tempo, non si possono trascurare le questioni ambientali legate alle emissioni di carbonio e di gas serra nell'atmosfera dovute all'uso di risorse non rinnovabili. Per questi motivi, i bio-leganti sono attualmente considerati una soluzione promettente per le pavimentazioni stradali flessibili. Essi sono definiti come leganti bituminosi in cui il bitume, che deriva dal processo di distillazione del petrolio greggio, è interamente o parzialmente sostituito da varie bio-risorse come rifiuti animali, bio-oli (legno, girasole, mais, soia), olio di scarto da cucina, lignina ecc. Attualmente, uno dei problemi principali è quello di garantire che i bio-leganti offrano buone prestazioni, almeno comparabili a quelle dei materiali convenzionali. Tuttavia, la conoscenza di tali materiali è ancora limitata in termini di prestazioni e, soprattutto, di durata nel tempo.
Alla luce di queste premesse, la presente ricerca di dottorato (cofinanziata dall'azienda petrolchimica svedese Nynas AB) si propone di valutare scientificamente la fattibilità della parziale sostituzione del bitume con un bio-olio e diversi tipi di lignina derivanti da sottoprodotti della lavorazione del legno e della carta. A tal fine, è stato condotto un ampio programma sperimentale che prevedeva analisi chimiche e reologiche avanzate sui bio-leganti selezionati. Successivamente, gli stessi bio-leganti ottenuti in laboratorio sono stati impiegati per produrre bio-miscele, successivamente sottoposte a un'ampia campagna di caratterizzazione meccanica che ha incluso indagini a bassa, media e alta temperatura, prove di adesione con gli aggregati lapidei, suscettibilità termica, all’umidità e all'invecchiamento.
Tutti i risultati ottenuti incoraggiano fortemente l'uso di questo tipo di bio-leganti, che possono rappresentare una valida alternativa ai bitumi tradizionali. Infatti, lo studio ha dimostrato prestazioni perfettamente comparabili o, in alcuni casi, addirittura migliori, suggerendo i potenziali vantaggi non solo dal punto di vista ambientale ed economico, ma anche da un punto di vista prestazionale.Nowadays, one of the main interests of modern society is to replace increasingly larger quantities of petroleum-derived products, which is a non-renewable source progressively depleting. In the last decades, the use of bio-materials has gained notable interest in the civil engineering sector. In this context, the road industry is interested in developing new “green” solutions, promoting sustainability and circular economy principles. In fact, given the rapid growth of cities and traffic volumes, the demand for raw materials for pavement construction and maintenance has dramatically increased, along with their price. At the same time, the environmental issues related to the carbon footprint and greenhouse gas emissions in the atmosphere due to the use of non-renewable resources cannot be neglected. For these reasons, bio-binders are currently considered a promising solution for flexible pavements. They are defined as bituminous binders in which bitumen, which derives from the distillation process of crude oil, is entirely or partially replaced with various bio-resources such as animal waste, bio-oils (wood, sunflower, corn, soybean), waste cooking oil, lignin etc. Currently, one of the main issues is to ensure that bio-binders offer good performance, at least comparable with that offered by conventional materials. However, the knowledge of these materials is still limited in terms of performance and, above all, durability over time.
Given this background, this PhD research (co-financed by the Swedish petrochemical company Nynas AB), aims to scientifically evaluate the feasibility of partially replacing bitumen with a wood-based bio-oil and different kind of lignin deriving from by-products of wood pulp and paper industry. To this end, an extensive experimental program was carried out involving advanced chemical and rheological analysis on the selected bio-binders. Then, the laboratory-produced bio-binders were used to produce bio-asphalt mixtures, which were subjected to a wide mechanical characterization campaign, including low-, medium- and high-temperature investigations, adhesion with aggregates, thermal, moisture and aging susceptibility.
Based on the overall findings, all elements encourage the use of such kind of bio-binders as a valid alternative to traditional bitumens. Indeed, the study demonstrate perfectly comparable, or, in some cases, even better performances were identified, while suggesting the potential benefits from technical, environmental and economic point of view
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
Writers Club with Faculty Advisor Dr. William Calvert and Guest Mrs. C.W. Daugette
No full textThese individuals may have been members of the Writers Club at Jacksonville State College circa 1954. Shown inside on campus they are gathered with faculty advisor Dr. William Calvert and guest Mrs. C.W. Daugette. (circa Spring 1954)https://digitalcommons.jsu.edu/lib-ac-histimg/2976/thumbnail.jp
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
Evaluation of the hCMEC/D3 cell line, a new "in vitro" model of the human blood-brain barrier for transport and gene regulation studies
Get PDFBrain endothelial capillary cells form the blood-brain barrier (BBB), a highly selective
membrane between the peripheral blood and the central nervous system. The main
functions of the BBB are to protect the brain tissue by preventing the entry of toxic
compounds and to supply it with nutrients in order to assure proper function. Tight
junctions are the key elements for the establishment of a tight barrier and seal the
intercellular gaps against passive diffusion of hydrophilic compounds. A second important
characteristic of the brain capillary endothelial cells are transport proteins that prevent
brain penetration of their substrates by pumping them back in the blood. These
compounds include a series of clinically used drugs. Important drug efflux transporters
located at the BBB are P-glycoprotein (P-gp), the breast cancer resistance protein
(BCRP) and the family of multidrug resistance proteins (MRP).
During drug development, the question of whether a drug candidate reaches the brain
tissue is of great importance. Therefore, models are needed to predict the BBB
permeability of new compounds. In the past, in vitro models have been developed to
address this question. These models include isolated brain capillaries, isolated primary
brain capillary endothelial cells and BBB cell lines of various origins. A major problem
encountered with these cell lines was an insufficient paracellular resistance.
Recently, the hCMEC/D3 cell line was generated by immortalizing primary human brain
endothelial cells. In culture this cell line shows a morphology that closely resembles to
primary cells, forms tight monolayers and expresses BBB markers such as chemokine
receptors, tight junctional molecules and ATP binding cassette (ABC)-transporters.
The aim of this thesis was to evaluate the hCMEC/D3 cell line as an in vitro model of the
human BBB to study 1) permeability properties including para- and transcellular diffusion
as well as active transport 2) the influence of endo- and exogenous factors on the
paracellular permeability and 3) the regulation of breast cancer resistance protein and Pglycoprotein
by pro-inflammatory cytokines.
The first study describes the characterization of the hCMEC/D3 cells as an in vitro model
of the human BBB for permeability studies (section Error! Reference source not
found.). The ability of the cells to allow discrimination between para- and transcellular
diffusion was investigated by measuring the transport of a series of compounds with
different physicochemical properties. A ratio of 2.8 was observed when comparing the
permeabilities of the compounds with the highest and the lowest diffusion rate. The
passive permeability of sucrose could be reduced significantly by replacing fetal calf
serum with human serum. Furthermore, quantitative mRNA expression of the ABCtransporters
P-gp, BCRP, MRP1, MRP2, MRP3, MRP4, MRP5 as well as the human
transferrin receptor (hTfR) was shown. Protein expression of P-gp, BCRP and the hTfR
was detected and functional activity of P-gp, BCRP and the MRPs was investigated in
efflux experiments. Furthermore, bidirectional P-gp transport activity was observed.
In a second project the impact of endo- and exogenous factors on the paracellular
permeability of hCMEC/D3 monolayers was assessed, since it is know that the molecular
assembly of tight junctions depends on the surrounding milieu (section Error! Reference
source not found.). Based on reports in the literature, the cells were incubated with a
variety of compounds that included anti-inflammatory drugs, growth factors and
antioxidants. The effects on the monolayer tightness of hCMEC/D3 were investigated by
measuring the transport of sucrose, a paracellular permeability marker. N-acetylcystein
(NAC), atorvastatin and sodium nitroprusside (SNP) reduced the sucrose permeability
significantly, and slightly increased zonula occludens protein (ZO-1) expression.
Additionally, NAC and SNP reduced the generation of reactive oxygen species (ROS),
which have been reported to disrupt the assembly of tight junctions.
The effect of the pro-inflammatory cytokines IL-1[beta], IL-6 and TNF-[alpha] on the expression and
activity of the ABC-transporters BCRP and P-gp was investigated in the hCMEC/D3 cell
line (section Error! Reference source not found.). IL-1[beta], IL-6 and TNF-[alpha], which are
know to be elevated during various diseases, suppressed significantly BCRP mRNA
expression. In addition, BCRP activity was reduced under the influence of all tested
cytokines, as shown by efflux experiments. P-gp mRNA levels were slightly reduced by
IL-6 but significantly increased after TNF-[alpha] treatment. TNF-[alpha] also increased the protein
expression of P-gp. This in vitro study indicates that expression levels of BCRP and P-gp
at the BBB might be altered during acute or chronic inflammation, resulting in a changed
brain penetration of their substrates.
In an isolated project, the pharmacokinetics and pharmacodynamics of increasing oral
doses of the satiety peptides GLP-1 and PYY3-36 were assessed in healthy male
volunteers. Oral administration of either peptide induced a rapid and dose-dependent
increase in plasma drug concentrations. Oral administration of GLP-1 induced a potent
effect on insulin release and both peptides suppressed ghrelin secretion. In conclusion,
this study showed, for the first time, that satiety peptides such as GLP-1 and PYY3-36
can be orally delivered safely and effectively in humans
[[alternative]]On The Bridge of Heaven Written and Translated by S.I. Hsiung
No full text[[abstract]]The thesis aims to discuss the myth of "authority" with teh case of S.I.Hsiung's English novel, The Bridge of Heaven, and his own translation in Chinese, trying to elaborage on the equality between the author-as-translator and the non-author translators.
The thesis includes 7 chapters. Chapter 1 explains the research purpose and the motivation and outlines teh author of The Bridge of Heaven and the background behind his works. Chapter 2 details the research methods. Chapter 3 focues on literature review, in which the papers about subjectivity and intersubjectivity will be discussed so as to clarify the relationship between the subjectivity does not act as the sole principle for translation; the concept of "the death of author" will be used to break the myth of "authority" so as to subvert the view of father-son relationship that the works was born to its author. Chapter 5 turns to discuss teh translator's subjectivity , arguing that the non-author translators have their own subjectivity different from that of the author's. Hans-Georg Gadamer's viewpoints ofn the historicity of languages will be cited to break the advocacy that the author's own translation is the ideal paradigm. Chapter 6 empasizes on the complementary functions among different translations. Four passages of The Bridge of Heaven will be tgranslated following the principle of loyal to the original words. The translations will work as comparison to S.I.Hsiung's own translation. The purpose is to show different effects fo diversified translations under various subjectivity. Moreover, different translations will touch different points of the original works and displays many aspects of the original. Chapter 7 summarizes that the author's own translation is not necessarily perfect and other non-author translators definitely have the space to let their Muse sing.
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
- …
