9 research outputs found
Localisation and quantification of chemical functional groups on pulp fibres
Get PDFThesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: The distribution of different free chemical functional groups on wood and pulp
fibres was determined by means of atomic force microscopy (AFM) with
chemically modified tips. Because these functional groups show a higher
affinity to similar groups on the substrate surface during scanning, AFM
images were recorded using an additional digital pulsed-force mode (DPFM)
controller. This allowed the distribution of the chemical components to be
imaged and to a degree, also to be quantified. The investigated tip coatings
showed different sensitivities towards the major chemical components present
in wood fibres. These components were determined on spin-coated films as
well as wood fibres. It was possible to make a clear distinction between
cellulose and lignin in both cases. This technique could therefore be used to
differentiate between cellulose and lignin present on pulp fibre surfaces and to
confirm the successful removal of lignin by pulping.
The chemical composition of wood fibres and fibre surfaces of several acacia
and eucalyptus species, and hybrids originating from various growth sites in
South Africa, are compared. The objective was to determine the differences in
chemical surface composition due to genetics or site. The motivation for this
was to eventually facilitate a tailor-made supply of wood for pulping which
results in an optimal blend of fibres that can be pulped together with similar
yields. This, however, first requires a sound knowledge of the fibre properties.
The surface functionality on the single fibre level is a key property because it
determines how good inter-fibre bonding will be when paper is formed, which
in turn depends to a large degree on the amount of free hydroxyl groups that
are available and therefore on the cellulose content on the fibre surface.
The cellulose and lignin contents on the fibre surface were determined with
chemical force microscopy (CFM), a variation of AFM. CFM involves the use
of chemically modified tip using selected functional groups. Since, the general
bulk composition of the fibre and the surface composition differ, both
parameters were determined. Significant differences in the cellulose and lignin
content on fibre surfaces were found, with regard to genotype and site, respectively. In some, but not all, cases the surface composition of wood
fibres followed the bulk composition and differences were generally more
pronounced. Differences due to genotype were significant, especially with
regards to the surface lignin content - but variation due to site was also
distinctly recognisable.
This variation in surface functionality could be the reason why some pulpwood
blends result in a lower pulp yield and different quality.AFRIKAANSE OPSOMMING: Die verspreiding van verskillende vrye chemiese funksionele groepe op hout
en pulpvesels is bepaal deur middel van atoomkragmikroskopie (AFM), met
chemies-gemodifiseerde punte (tips). Omdat hierdie funksionele groepe 'n
hoër verwantskap tot soortgelyke groepe op die substraat se oppervlak
gedurende skandering toon, kan AFM-beelde wat met 'n addisionele
digitalepulskragmodusbeheerstel bepaal word dit moontlik maak om die
verspreiding van die chemiese komponente uit te beeld en tot op ‘n sekere
vlak te kwantifiseer. Die ondersoekte punt-oppervlakmiddels het verskillende
sensitiwiteite teenoor die hoof chemiese komponente in die houtvesels en
spin-bestrykte films getoon. 'n Duidelike onderskeid kon in beide gevalle
tussen sellulose en lignien gemaak word. Hierdie tegniek kon dus gebruik
word om te onderskei tussen sellulose en lignien wat op die
pulpveseloppervlak teenwoordig was en om die suksesvolle verwydering van
lignien gedurende die pulpproses (pulping) te bevestig.
In hierdie studie is die chemiese samestelling van houtvesels en die
veseloppervlaktes van verskeie akasia en eucalyptus spesies, asook dié van
gekruisde spesies wat van verskeie werfliggings in Suid-Afrika afkomstig is,
vergelyk. Die doel was om te toets vir verskille in chemiese
oppervlaksamestellings, wat veroorsaak kan word deur genetika of werf
verskille, met die uiteindelike mikpunt om ‘n spesiaal-gemaakte voorraad van
hout vir pulping te fasiliteer, wat kan lei tot 'n optimale mengsel van vesels wat
saam gepulp kan word met soortgelyke opbrengs. Dit vereis natuurlik 'n goeie
kennis van die veseleienskappe. Die oppervlakfunksionering van enkel vesels
is ‘n kritiese eienskap omdat dit bepaal hoe goed interveselverbindings sal
wees wanneer papier gevorm word. Dit hang tot ‘n groot mate af van die
hoeveelheid vry hydroksielgroepe wat beskikbaar is en dus ook van die
sellulose inhoud op die veseloppervlak.
Die sellulose- en lignieninhoud op die veseloppervlak is bepaal met chemiese
kragmikroskopie – 'n variasie van atoomkragmikroskopie. Omdat die
algemene grootmaat samestelling van die vesel en die oppervlaksamestelling mag verskil, is altwee parameters bepaal. Beduidende verskille in die
sellulose- en lignieninhoud, met betrekking tot genotipe en werfligging, op
veseloppervlaktes is gevind. In sommige, maar nie alle, gevalle het die
oppervlaksamestelling van houtvesels ooreengestem met die
grootmaatsamestelling, en verskille was oor die algemeen meer beduidend.
Verskille as gevolg van genotipe was beduidend, veral met betrekking tot die
oppervlak lignieninhoud, maar variasie as gevolg van werfligging was ook
duidelik herkenbaar.
Hierdie variasie in oppervlakfunksionering kan die rede wees hoekom
sommige pulp–hout mengsels lei tot 'n laer pulpopbrengs en verskille in
kwaliteit.Doctora
Imaging and quantifying the different crystalline structures of polypropylene with the atomic force microscope
Get PDFThesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006.Isotactic polypropylene (iPP) exists in four different crystalline phases: α-, β-, γ- and
the mesomorphic (smectic) form. The α-phase is probably the most predominant form
of iPP with a monoclinic unit cell, whereas the unit cell of the γ-phase is
orthorhombic. The aim of this study was to examine the ability of AFM to identify
the α and γ crystalline forms of polypropylene and polypropylene copolymers that
were not especially treated.
Spherulites imaged on propylene-ethylene random copolymer surfaces had diameters
ranging from 10-30μm and predominantly radial lamellae. The cross-hatching
phenomenon of isotactic polypropylene was observed for samples containing both the
α- and γ-phase. Two types of γ-phase spherulites were observed, namely a featherlike
form for samples with a high content of the γ-phase and a bundle-like form with
varying sizes, which is typical for the mixed structure of both α- and γ-forms. In some
images of polypropylene-ethylene copolymer sample lozenge-shaped structures could
be observed between the γ-spherulites, which might be single polyethylene crystals.
Both the α- and γ-phase of iPP were successfully imaged and identified with AFM
without prior treatment of the surface. The degree of crystallinity obtained from AFM
images was calculated as a percentage of the surface area exhibiting regular
structures. The results compared well to X-ray results
High Density Polyethylene/Libyan Kaolin Clay Nanocomposites: Effect of Clay Particle Size on Rheological, Surface and Mechanical Properties
No full textAdapting authoritarianism: institutions and co-optation in Egypt and Syria
No full textThis PhD thesis compares Egypt and Syria’s authoritarian political systems. While the tendency in social science political research treats Egypt and Syria as similarly authoritarian, this research emphasizes differences between the two systems with special reference to institutions and co-optation. Rather than reducibly understanding Egypt and Syria as sharing similar histories, institutional arrangements, or ascribing to the oft-repeated convention that “Syria is Egypt but 10 years behind,” this thesis focuses on how events and individual histories shaped each states current institutional strengthens and weaknesses. Specifically, it explains the how varying institutional politicization or de-politicization affects each state’s capabilities for co-opting elite and non-elite individuals.
Beginning with a theoretical framework that considers the limited utility of democratization and transition theoretical approaches, the work underscores the persistence and durability of authoritarianism. Chapter two details the politicized institutional divergence between Egypt and Syria that began in the 1970s. Chapter three and four examines how institutional politicization or de-politicization affects elite and non-elite individual co-optation in Egypt and Syria. Chapter five discusses the study’s general conclusions and theoretical implications.
This thesis’s argument is that Egypt and Syria co-opt elites and non-elites differently because of the varying degrees of institutional politicization in each governance system. Rather than view one country as more politically developed than the other, this work argues that Syria’s political institutions are more politicized than their Egyptian counterparts. Syria’s political arena is, thus, described as politicized-patrimonialism. Syria’s politicized-patrimonial arena produces uneven co-optation of elites and non-elites as they are diffused through competing institutions. Conversely, the Egyptian political arena remains highly personalized as weak institutions and individuals are manipulated and molded according to the president’s ruling clique. This is referred to as personalized-patrimonialism. As a consequence, Egypt’s political establishment demonstrates more flexibility in ad hoc altering and adapting its arena depending on the emergence of crises.
This study’s theoretical implications suggest that, contrary to modernization and democratization theory’s adage that institutions lead to a political development, politicized institutions within a patrimonial order actually hinder regime adaptation because consensus is harder to achieve and maintain. It is within this context that Egypt’s de-politicized institutional framework advantages its top political elite. In this reading of Egyptian and Syrian politics, Egypt’s personalized political arena is more adaptable than Syria’s. These conclusions do not indicate that political reform is a process underway in either state
Additional file 1 of Analysis of variance of injection moulding process parameters and clay particles size effects on impact strength, shrinkage and warpage of polyethylene/kaolin clay composites
No full textAdditional file 1: Table S1. One way ANOVA results of Shrinkage: effect of Pack pressure. Table S2. One way ANOVA results of Shrinkage: effect of Pack Time. Table S3. One way ANOVA results of Warpage: effect of Injection temperature. Table S4. One way ANOVA results of Warpage: effect of Pack pressure. Table S5. One way ANOVA results of Warpage: effect of Pack Time. Table S6. One way ANOVA results of Impact strength: effect of Pack pressure. Table S7. One way ANOVA results of Impact strength: effect of Pack Time
Currículo e didática da diferença : dançário de EIS AICE
Get PDFEsta escrita transcorre por linhas que trabalham um currículo e uma didática da tradução. Esse ato de escrever alia-se à imagem poética para pensar deslocamentos dos sete elementos que constituem os blocos de pensamento de um currículo (EIS) e de uma didática (AICE). A escrita vem do corpo do pensamento e da linguagem, que se violentam ao encontro de pensar como criação, sob os conceitos filosóficos de Deleuze e da filosofia da diferença. Os significados das palavras transpassam o sentido literal, ao serem usadas como imagens poéticas e transcriadas num Dançário de EIS AICE. Produz poética na tentativa de pôr, em movimentos, textos das imagens eisaiceanas ao serem operacionalizados com materiais desenvolvidos no Projeto Escrileituras: um modo de ler e escrever em meio à vida, Obeduc/CAPES/INEP (2011-2014) problematizando a ação docente nos espaços tradutórios do currículo e da didática ao mostrar suas experimentações em três blocos de escrita. De modo que as palavras movam-se por um devir dançante buscando um vazio de fala, de um autor e de uma escrileitura por vir. Propõem dispor, diante dos arquivos operatórios, diferentes formas de pensar sobre o bloco de pensamento de EIS AICE.This writing works with a curriculum and didactics of the translation. This act of writing join the poetic image to think about displacements of the seven elements that constitute the blocks of thought about a curriculum (EIS) and didactics (AICE). The writing comes from the body of the thought and the language that they clash at time to think of creation, under the philosophical concepts of Deleuze and the philosophy of difference. The meanings of the words transcend the literal meaning, when they are get using as poetic images and recreated in an Dancing of EIS AICE. It produces poetics in the at tempt to put, agoing, texts of the eisaiceanas images when they are operat ionalized with materials developed in the Escrileituras Project: um modo de ler e escrever em meio à vida, Obeduc / CAPES / INEP (2011-2014), problematizing the teaching activity in spaces of the curriculum and didactics by showing their experiments in three writing blocks. So that the words move through a dancing becoming, seeking a void of speech, of an author and of a writreading to come. The writing proposes to provide, before the operative archives, different ways of thinking about the block of thought of EIS AICE
Nota sobre un nuevo “falso” en árabe, de moriscos en el exilio, antes de la expulsión general (¿Túnez, 1603?): la pseudo-Tuḥfa de Turmeda (3a parte)
No full textNota erudita sobre un nuevo y novedoso ejemplo de textos “falsos” de moriscos (“falsificaciones”, en el sentido de que no pertenecen auténticamente al autor, época, temática o sociedad a la que se atribuyen aparentemente), según una práctica bastante extendida en España y en otros países, también en los siglos XVI-XVII. Se presentan así unas ampliaciones de la parte teológica de una obra árabe de 1420, polémica anticristiana del escritor mallorquín convertido al Islam en Túnez Anselm Turmeda /Abdalah At-Tarchumán, presuntamente manipulada a principios del XVII, en ambiente de “falsos” moriscos, españoles y tunecinos. Anomalías teológicas detectadas ya en una tesis doctoral de 1967 y sus ediciones en 1971 y 1994 (en árabe con traducción al castellano) y en ediciones abreviadas en 1988 y 2005 (en catalán), se explican por comparación con otros “falsos” moriscos granadinos y tunecinos (Historia verdadera del Rey Don Rodrigo, Pergamino de la Torre Turpiana, Libros plúmbeos del Sacromonte, Evangelio de San Bernabé,...) y situando su fechación en época posterior al Concilio de Trento (1545-1563), cuyos decretos afectaron a los moriscos de España, obligados durante el siglo XVI a ser “falsos cristianos” y cripto-musulmanes.Erudite note on a new and novel example of Moriscos’ “false” texts (“falsifications”, in the sense that they do not belong to the author, epoch, subject matter or society to whom they want to be), in a practice extended enough in Spain and in other countries, also in the centuries XVI-XVII. We show some amplifications of the theological part of an Arabic work of 1420, an anti-Christian polemic of the Majorcan writer converted to the Islam in Tunis Anselm Turmeda/Abdalah At-Tarchumán, presumably manipulated at the beginning of the XVIIth, in an environment of “false” texts Spanish and Tunisian moriscos. These Theological anomalies were already detected in a doctoral thesis of 1967 and its editions in 1971 and 1994 (in Arabic with Spanish translation) and in abridged editions in 1988 and 2005 (in Catalan). They can be explained by its comparison with other morisco “false” texts form Granada and Tunis (Truly History of the King Don Rodrigo, Parchment of the Turpiana Tower, Lead Books of the Sacromonte, Gospel of Saint Barnabas...) and placing its dating after the Council of Trent (1545-1563), whose decrees affected the Moriscos of Spain, forced during the XVIth century to being “false Christians” and crypto-Muslims
SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study
Get PDFBackground: Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods: The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18–49, 50–69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results: NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion: As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population. © The Author(s) 2021. Published by Oxford University Press on behalf of BJS Society Ltd
Proceedings of First Conference for Engineering Sciences and Technology: Vol. 2
Get PDFThis volume contains contributed articles of Track 4, Track 5 & Track 6, presented in the conference CEST-2018, organized by Faculty of Engineering Garaboulli, and Faculty of Engineering, Al-khoms, Elmergib University (Libya) on 25-27 September 2018.
Track 4: Industrial, Structural Technologies and Science Material
Track 5: Engineering Systems and Sustainable Development
Track 6: Engineering Management
Other articles of Track 1, 2 & 3 have been published in volume 1 of the proceedings at this lin
