Letteratura scientifica selezionata sul tema "Anti-scaling"

Scale formation in the digester during kraft pulping represents a great problem in pulp mills. Scaling reduces pulping control and efficiency, increasing energy costs and leading to cleaning breakdowns, with subsequent losses in productivity. The kraft process promotes CaCO3 scaling due to high calcium ion and carbonate concentrations, as well as high alkalinity and temperature levels, which increase the speed with which liquors reach a state of supersaturation. This work examines the action of diethylene triamine penta(methylene phosphonic acid) (DTPMPA), either alone or combined with commercial anti-scaling agents, as an inhibitor of calcium carbonate precipitation in the kraft pulping of Pinus taeda. The theoretical amount of calcium deposited in the digester was obtained by mass balance. Soluble calcium was stable throughout cooking when using the phosphonates alone or combined with anti-scaling agents. When adding only DTPMPA, calcium stays in the pulp, rather than forming deposits.

Every year, water well inspection operations accounted for 27.3% of the total water well operations due to corrosion and scaling of downhole injection tools in the Dagang Southern Oil Field, which seriously affects the validity period of the injection string and the effect of the injection, greatly increasing the production cost. Therefore, through the research and experiment of anti-corrosion and anti-scaling technologies such as 00Cr25Ni7Mo3N dual-phase steel material, TiN coating, Ni-W-P coating and Ni-W-P-nSiO2 composite coating, a new type of anti-corrosion and anti-scaling technology for downhole injectiong tools has been developed. The field test results show that under the premise of ensuring the mechanical performance of the tools, the average corrosion rate of the supporting tools using the new anti-corrosion and anti-scaling technology is 0.0048mm/a, which is far lower than the industry standard 0.076mm/a. The successful test of this technology is of great significance to increase the effective period of the southern oilfield split injection and reduce production costs.

In order to put forward the Anti-scale measures of shaft in Shunan Gas Mine and guarantee the normal production of gas field,the composition as well as the water quality and scaling type for gas production water at the typical shaft mouth of Shunan Gas Mine are analyzed and the scaling mechanism of shaft and the influencing factors are described as well as the anti-scale agent and the solid anti-scale blocks pertaining to the scaling of shaft in Shunan Gas Mine are obtained.

Can new types of anti-scaling devices prevent scaling on condensing pipes in industrial cooling condensers and supersede conventional water treatment? To examine this question a test method has been developed, test rigs have been built and different kinds of anti-scale devices have been tested. As cooling towers are based on an open-air system with evaporation of water they will have higher demands on the effectiveness of the anti-scale devices compared to the closed systems which are typical drinking water systems in buildings. The test method is based on an open-air system. The rigs are mobile and can be used to give an indication of whether it is possible to treat the local water with an anti-scale device. The result of the test is a scaling rate and a germination time. In addition to these tests the anti-scale devices have been tested in the field at cooling condensers.

Atherosclerosis is an insidious disease with serious morbidity and mortality including ischemic heart disease, stroke, and myocardial infarction. This condition is progressive and can start early in life eventually leading to large plaques and arterial occlusion. Two key components of this process are the immune system and lipids; in particular, LDL which accumulates within the arterial walls and macrophages which recognize and engulf oxidized-LDL (oxLDL) to form foam cells. Knowing that certain antibodies directed against bacterial antigens such as phosphorylcholine (PC) and cardiolipin (CL) show opsonizing cross-reactivity with oxLDL it can be proposed that there is a link between immune responses to periodontal bacteria and atherosclerosis. The aim of this investigation was to determine whether periodontal bacteria are capable of inducing serum antibodies potentially involved in cardiovascular diseases; specifically, IgG anti-PC, IgG anti-CL, and IgM anti-CL. To test this, 17 subjects with chronic periodontitis received scaling and root planing in conjunction with blood sample analysis to determine if periodontal instrumentation resulted in changes in these serum antibodies. If plaque bacteria are responsible for an immune response then serum levels of these antibodies should decrease following periodontal therapy. We found that serum levels of IgG anti-PC, IgG anti-CL, and IgM anti-CL decreased following periodontal scaling and root planing but the change was significant only for IgG anti-PC (P 0.045). Serum levels of IgM anti-CL approached significance (P 0.054). The results support the hypothesis that the immune response to periodontal bacterial microflora contributes to serum concentrations of antiphospholipid antibodies.

Increasing environmental concerns and discharge limitations have imposed additional challenges in treating process waters. Thus, the concept of "Green Chemistry" was proposed and green scale inhibitors became a focus of water treatment technology. Finding some economical and environmentally friendly inhibitors is one of the major research focuses nowadays. In this dissertation, the inhibition performance of different phosphonates as CaCO3 scale inhibitors in simulated cooling water was evaluated. Homo-, co-, and ter-polymers were also investigated for their performance as Ca-phosphonate inhibitors. Addition of polymers as inhibitors with phosphonates could reduce Ca-phosphonate precipitation and enhance the inhibition efficiency for CaCO3 scale. The synergistic effect of polyaspartic acid (PASP) and Polyepoxysuccinic acid (PESA) on inhibition of scaling has been studied using both static and dynamic methods. Results showed that the anti-scaling performance of PASP combined with PESA was superior to that of PASP or PESA alone for CaCO3, CaSO4 and BaSO4 scale. The influence of dosage, temperature and Ca2+ concentration was also investigated in simulated cooling water circuit. Moreover, SEM analysis demonstrated the modification of crystalline morphology in the presence of PASP and PESA. In this work, we also investigated the respective inhibition effectiveness of copper and zinc ions for scaling in drinking water by the method of Rapid Controlled Precipitation (RCP). The results indicated that the zinc ion and copper ion were high efficient inhibitors of low concentration, and the analysis of SEM and IR showed that copper and zinc ions could affect the calcium carbonate germination and change the crystal morphology. Moreover, the influence of temperature and dissolved CO2 on the scaling potential of a mineral water (Salvetat) in the presence of copper and zinc ions was studied by laboratory experiments. An ideal scale inhibitor should be a solid form compound having a very low solubility, but the value of this solubility is big enough to ensure a total scaling inhibition. A new type of scale inhibitor we synthesized possesses these properties. In fact, the synthesized inhibitor has a very poor solubility (about 1. 5 mg/L) at 20°C for Paris's tap water. Its anti-scaling properties have been evaluated by RCP method. A complete scaling inhibition was obtained with a concentration of 30 µg/L (ppb) for Salvetat water at 30°C. Moreover, the introduction of the synthesized solid inhibitor to a water system can be easily realized by using a cartridge
Les exigences environnementales imposent de nombreux défis dans le domaine du traitement des eaux. Ainsi, le concept de " chimie verte " a-t-il été proposé et l'utilisation des produits chimiques " écologiques " est devenue une nécessité. Il est donc d'une importance primordiale d'élaborer des inhibiteurs d'entartrage " verts " afin de combattre les phénomènes d'entartrage qui ont des conséquences désastreuses, voire catastrophiques, dans certaines installations industrielles, comme les circuits de refroidissement des centrales nucléaires. Dans cette étude, l'efficacité de différents inhibiteurs d'entartrage de CaCO3 a été évaluée dans un circuit de refroidissement simulé. En tant qu'inhibiteurs de précipitation de Ca-phosphonates, des homo-, co- et ter-polymères ont également été étudiés en matière de leur efficacité. En fait, l'ajout de ces polymères dans l'eau contenant des phosphonates peut réduire la précipitation du Ca-phosphonates et renforcer l'efficacité d'inhibition de l'entartrage du CaCO3. L'effet synergétique de l'acide polyaspartique (PASP) et de l'acide polyepoxysuccinique (PESA) sur l'inhibition de l'entartrage a été étudié en utilisant à la fois des méthodes statique et dynamique. Les résultats obtenus montrent que l'efficacité inhibitrice du mélange PASP-PESA est supérieure à celle du PASP ou du PESA pris individuellement pour la précipitation de CaCO3, CaSO4 et BaSO4. L'effet de la concentration des inhibiteurs, de la température et de la concentration de Ca2+ ont également été étudié. Par ailleurs, l'analyse par MEB a bien montré la modification de morphologie des précipités en présence du PASP et du PESA. Dans ce travail, on a également étudié les propriétés inhibitrices des ions Cu2+ et Zn2+ dans l'eau potable avec la méthode de Précipitation Contrôlée Rapide (PCR) développée dans le Laboratoire (LIM). Les résultats obtenus montrent que ces ions métalliques sont des inhibiteurs très efficaces à faible concentration. De plus, l'analyse par MEB et IR indiquent que les ces ions peuvent affecter la morphologie cristalline du CaCO3. Par ailleurs, l'influence de la température et du CO2 dissous sur le pouvoir entartrant de l'eau minérale de Salvetat (utilisée comme eau de référence), en présence des ions Cu2+ et Zn2+, a été étudiée expérimentalement. L'inhibiteur idéal serait un composé sous forme solide dont la solubilité serait très faible, mais largement suffisante pour assurer une inhibition totale de l'entartrage. Il pourrait ainsi être mis en contact directement avec l'eau à traiter sans que l'on ait à se soucier de sa concentration qui serait régulée automatiquement par sa solubilité. La synthèse de tels inhibiteurs a été réalisée et leur efficacité a été évaluée durant cette thèse. En fait, les inhibiteurs solides obtenus ont une solubilité de l'ordre de 1,5 mg/L dans l'eau du robinet de Paris et ils donnent une inhibition totale de CaCO3 dans la même eau avec une concentration seulement de 30 ppb (μg/L). De plus, l'introduction de ces inhibiteurs solides peut être réalisée facilement par une cartouche

Orientadores: Marcio Zaffalon Casati, Sergio de Toledo
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-10T01:28:41Z (GMT). No. of bitstreams: 1 Ribeiro_EricaDelPeloso_D.pdf: 610626 bytes, checksum: 77eba31c722b912eac6fdb2cdbc2b89a (MD5) Previous issue date: 2007
Resumo: O objetivo do presente estudo foi avaliar o efeito do debridamento periodontal associado ou não à administração sistêmica de metronidazol e amoxicilina no tratamento da periodontite crônica avançada. Foram selecionados 50 pacientes com pelo menos 8 dentes com sangramento à sondagem (SS) e profundidade de sondagem (PS) = 5 mm, sendo 2 dentes com PS = 6 mm e mais 2 com PS = 7 mm. Os pacientes foram divididos, aleatoriamente, em 4 grupos: raspagem e alisamento radicular + placebo (RAR); RAR + metronidazol e amoxicilina (RAR/AB); debridamento periodontal + placebo (DB) e DB + metronidazol e amoxicilina (DB/AB). Os seguintes parâmetros clínicos foram avaliados: índice de placa, índice gengival, SS, posição da margem gengival, PS e nível clínico de inserção relativo (NICr). A avaliação microbiológica foi feita através da reação da polimerase em cadeia (PCR) em tempo real para quantificação de Porphyromonas gingivalis, Tannerella forsythia e Aggregatibacter actinomycetemcomitans. O teste imunoenzimático (ELISA) permitiu a detecção dos níveis de PGE2, IL-1ß, IFN-? e IL-10 no fluido gengival. Os parâmetros descritos foram avaliados antes do tratamento, 1, 3 e 6 meses após. Não foi observada diferença estatística entre os grupos quanto ao SS, PMG e NICr (p>0,05). Em relação à redução na PS, esta foi, no 6° mês, inferior no grupo DB quando comparada aos grupos RAR/AB e DB/AB (p<0,05). Não foi detectada diferença estatística entre os grupos na prevalência e quantidade de P. gingivalis, T. forsythia e A. actinomycetemcomitans tanto em bolsas inicialmente moderadas e profundas. Também não foi observada diferença entre os tratamentos quanto aos níveis de PGE2, IL-1ß, IFN-?, IL-10 e na proporção IL-1ß/IL-10. Pode-se concluir, portanto, que o debridamento periodontal é uma abordagem justificável para tratamento da periodontite crônica avançada e que a único benefício da utilização adjunta de metronidazol e amoxicilina parece ser a redução na necessidade de retratamento.
Abstract: The aim of the present study was to evaluate the effect of periodontal debridement, with or without the systemic administration of metronidazole and amoxicillin, in the treatment of severe chronic periodontitis. Fifty patients presenting at least 8 teeth with probing pocket depth (PPD) = 5 mm and bleeding on probing (BOP), out of which at least 2 teeth had PPD = 7 mm and a further 2 teeth with PPD = 6 mm, were selected. Patients were randomly divided into four groups: scaling and root planning + placebo (SRP); SRP + metronidazole and amoxicillin (SRP/AB); periodontal debridement + placebo (DB) and DB + metronidazole and amoxicillin (DB/AB). The following clinical outcomes were evaluated: visible plaque index, gingival index, BOP, position of the gingival margin (PGM), relative attachment level (RAL) and PPD. The microbiological analysis was done by real-time polymerase chain reaction (PCR) for quantification of Porphyromonas gingivalis, Tannerella forsythia and Aggregatibacter actinomycetemcomitans. The enzyme-linked immunosorbent assay technique (ELISA) permitted the detection of PGE2, IL-1ß, IL-10 and IFN-? levels in gingival crevicular fluid. All parameters were evaluated at baseline and 1, 3 and 6 months after periodontal treatment. No difference was observed between groups regarding BOP, PGM and RAL (p>0.05). Six months after treatment, the DB group showed less PPD reduction than SRP/AB and DB/AB groups (p<0.05). The results of realtime PCR failed to demonstrate significant differences between groups in the prevalence and quantity of A. actinomycetemcomitans, P. gingivalis and T. forsythia. Also, no difference was observed between groups in the levels of PGE2, IL-1ß, IFN-?, IL-10 and on the proportion of IL-1ß/IL-10. It can be concluded that periodontal debridement is a justified approach for the treatment of severe chronic periodontitis and that only benefit of the adjunct use of metronidazole and amoxicillin was the reduction in the need of retreatment.
Doutorado
Periodontia
Doutor em Clínica Odontológica

Utilisé dans l’entretien et le soin des gencives et des dents, le produit Gencix® (SAS Esprit d’éthique) a montré, d’après les observations cliniques des dentistes, une action anti-inflammatoire et nettoyante des dents. Ce dentifrice incorpore un extrait aqueux de feuilles de papayer. Afin d’en comprendre le mécanisme d’action en termes de métabolites actifs, un fractionnement bioguidé et une étude déréplicative associant LCUV- MSn et RMN du 13C ont été menés. L’activité relevée en clinique ne semble pas liée à un effet antibiofilm. Une activité anti-inflammatoire (anti-TNF-alpha) serait liée aux flavonoïdes plus ou moins glycosylés présents dans l’extraits. Nous avons en effet pu identifier quelques-uns des actifs comme la quercétine et le kaempferol, déjà décrits comme inhibiteurs de la libération du TNF- alpha. D'autres flavonols libres ou conjugués tels que la rutine, identifiés dans les fractions actives, peuvent également contribuer à l'activité anti-inflammatoire globale. Plus notablement, au cours de ce travail, des esters des acide malique et hydroxycinnamique ont pour la première fois été associés à une activité anticalcaire, en particulier l’acide caféoylmalique. Ce dernier agit sans doute en synergie avec d’autres composés analogues. Les différents groupements acides carboxyliques et hydroxyles présents dans ces dérivés agissent vraisemblablement en complexant les ions Ca2+. Au-delà de ces résultats, ces anticalcaires nouvellement identifiés apparaissent comme des actifs « verts » (non toxiques, n’entraînant pas de bioaccumulation et biodégradables), respectueux de l'environnement. Cette activité anticalcaire remarquable a fait l’objet d’un dépôt de brevet
Gencix® (SAS Esprit d’Ethique) is used for the maintenance and care of gums and teeth. Clinical observations reported from dentists showed that this product-integrating anaqueous Carica papaya leaf extract- showed teeth cleaning and anti-inflammatory properties. In order to understand the mechanism of action and the role of the metabolites of the plant extract, a bioguided fractionation and a dereplicative study associating LC-UV-MSn and 13C NMR were conducted. Clinical activity does not appear to be related to an antibiofilm effect. The anti-inflammatory (anti-TNF-alpha) activity is most probably associated with glycosylated flavonoids. We have been able to identify some of the active ingredients such as quercetin and kaempferol which are already known to inhibit the release of TNF-α. Other free or conjugated flavonols such as rutin, identified in the active fractions, may also contribute to the overall anti-inflammatory activity. Most notably, esters of malic and hydroxycinnamic acids were described for the first time as scaling inhibitors, particularly caffeoyl malate. This compounds probably acts in synergy with other analog compounds. The various hydroxyl and carboxylic groups present in these compounds are probably responsible for this activity by complexing Ca2+ ions. Beyond these results, these metabolites, which are newly identified as anti-scalant, appear as "green" (i. e. non-toxic, non-bioaccumulative and biodegradable) as well as environmentally friendly. Therefore, this outstanding scaling inhibition property was subjected to patent application

Background. Developing countries are undergoing a process of epidemiological transition from infectious to non-communicable diseases, described by the United Nations Secretary General Ban Ki-Moon as “a public health emergency in slow motion”. One of the most prevalent of these diseases, in sub-Saharan Africa, is hypertension, which is a complex chronic condition often referred to as the “silent killer” and a key contributor to the development of cardiovascular and cerebrovascular diseases. Hypertensive patients in this setting are estimated to increase from 74.7 million in 2008 to 125.5 million in 2025, a 68% increase. There is however an important gap between emerging high-level policies and recommendations, and the near-absence of practical guidance and experience delivering long-term medical care for non-communicable diseases within resources-limited health systems. To address this gap, our study consisted of field investigations to determine the minimum health systems requirements necessary to ensure successful delivery of anti-hypertensive medications when scaling-up interventions. Methods/Design. A cross-sectional analytic study was conducted in the Western Cape Province of South Africa using a mixed method approach with two sets of semi-structured interviews and simulation modeling. One set of interviews was conducted with health professionals involved in the care of hypertensive patients within nine community health centers (five urban and four rural) to understand the challenges associated with their care. The other set was used to map and assess the current supply chain management system of antihypertensive medications and involved key informants at different levels of the process. Finally, modeling and simulation tools with ARENA Software were used to estimate minimum numbers of health workers required to ensure successful delivery of medications when scaling up interventions. Results. The study found numerous challenges affecting the care of hypertensive patients in primary health care facilities and categorized these into five interconnected dimensions: Management of the visits within the PHC facility, Adequacy of human resources, Standardization of patients’ care, Infrastructure limitations, and Patients’ responsibilities. Potential solutions to overcome these challenges were explored in order to improve the care of the hypertensive patients in the PHC facilities. Mapping of the drug supply chain management system highlighted the complexity of the system. In fact many of the issues reported fell outside of the control of the provincial health department. The need for a more single comprehensive computer system to handle most of the functions of the drug supply management system was heavily emphasized. The modeling and simulation tool with ARENA Software estimated the type and number of health care professionals needed to provide appropriate services to a certain patient population based on the set targets. The sample data used showed how one can test the impact of various changes in the processes and staffing levels to minimize waiting times while increasing the daily patients’ intake at the facility. We found that with few additional nursing staff, that are more affordable and quicker to train than medical doctors and pharmacists, one can considerably improve the performance of the facilities in the care of hypertensive patients. Discussion. This investigation has highlighted the detailed processes in place for the care of hypertensive patients in primary health care facilities, identifying the challenges in providing such care. The potential solutions suggested by the study results, if implemented, should help improve services offered and ensure that the system remains sustainable when patients’ intake increases exponentially as a result of scaled up interventions. The weaknesses of the drug supply chain management system demand immediate action. The modeling and simulation tools used in this study, if used on an ongoing basis, could create more effective planning of needed resources, although their proper utilization will require extra training for managers. Whether there is sufficient political support to ensure the resources necessary to reach the provincial health department’s hypertension target remains to be seen, and would benefit with further economic studies to estimate the cost associated with tackling the hypertension epidemic.

Ce projet concerne le développement de différents revêtements hybrides (organiques-inorganiques) fonctionnalisés, élaborés par le procédé sol-gel, pour lutter contre l'entartrage, un problème majeur causé par la précipitation de minéraux, principalement le carbonate de calcium (CaCO3). Contrairement aux méthodes classiques basées sur l'ajout de molécules antitartres dans l'eau, ces revêtements offrent une solution durable en inhibant directement la formation du tartre à la surface d'un matériau. Les performances antitartres de ces films ont été évaluées avec précision grâce à un ensemble d'outils basés sur la microbalance à cristal de quartz (QCM), une technique très sensible capable de détecter les faibles masses déposées à la surface d'un résonateur à quartz. Les résultats ont montré une amélioration significative des performances antitartres des surfaces revêtues par rapport aux surfaces métalliques nues. L'influence de l'hydrophobicité sur l'inhibition du tartre a été étudiée en utilisant des réactifs et des précurseurs plus hydrophobes pour la synthèse des revêtements. Les résultats ont confirmé le rôle important de ce paramètre dans la lutte contre l'entartrage, démontrant que le film le plus hydrophobe présentait les meilleures performances antitartres. Enfin, les propriétés antitartres de films hybrides ont été étudiées, après avoir été imprégnés d'un inhibiteur, l'acide diéthylènetriamine-pentaméthylène phosphonique (DTPMPA). Cette stratégie a permis d'obtenir une inhibition totale de la formation de CaCO3 avec une valeur de l'énergie de formation du tartre, estimée par QCM, très élevée. Ce résultat a montré le potentiel prometteur de ces revêtements comme une alternative durable aux méthodes classiques d'inhibition du tartre, offrant une protection totale de la surface tout en préservant la qualité de l'eau
This project is focused on the development of functionalized hybrid coatings (organic-inorganic) prepared by the sol-gel process for antiscaling applications. Scale, a major issue caused by mineral precipitation, mainly the calcium carbonate (CaCO3), poses significant problems in various industries. These coatings offer a durable solution by directly inhibiting scale formation on the surface, unlike conventional scale inhibition methods that involve the addition of antiscalants directly into water. The antiscaling performance of these films was accurately assessed using a set of tools based on the quartz crystal microbalance (QCM), a highly sensitive technique to detect small masses of deposits on the surface. The results demonstrated a significant improvement in the antiscaling efficiency of coated surfaces compared to uncoated surfaces. The influence of the hydrophobicity on scale inhibition was investigated by using more hydrophobic reagents and precursors for coating elaboration. The results confirmed the fundamental role of this parameter in the scaling process, as the most hydrophobic film exhibited the best anti-scaling performance. The final phase of the project involved studying the antiscaling properties of hybrid coatings impregnated with an inhibitor, diethylenetriamine pentamethylene phosphonic acid (DTPMPA). This strategy successfully achieved total inhibition of CaCO3 formation on the surface, as the energy of scale formation, estimated through QCM measurements, showed the highest value. This outcome highlighted the great potential of these coatings as a sustainable alternative to conventional scale inhibition methods, allowing total inhibition of scaling without compromising water quality

Le but de cette thèse est de définir puis d'étudier différentes notions d'irrégularité uniforme ou ponctuelle permettant de traduire le fait qu'une fonction peut avoir des 'grands accroissements' à toutes les échelles. Pour cela on 'inverse' les notions de régularité Höldérienne usuelles. L'objectif principal du travail est ensuite de relier ces différentes notions à la théorie des ondelettes. Les critères ondelettes établis vont ainsi permettre de définir des fonctions ou des champs aléatoires dont le comportement est différent suivant la gamme d'échelles considérée. Par ailleurs, si on se place du point de vue ponctuel, une question naturelle est celle de la définition d'une analyse multifractale -dite faible- liée à la notion d'irrégularité ponctuelle. Les ondelettes vont alors permettre de définir des séries d'ondelettes multifractales pour l'irrégularité ponctuelle. Enfin, nous étudions des exemples de champs aléatoires où des propriétés de régularité directionelle apparaissent. Nous nous sommes ainsi centré sur l'étude d'un modèle de champ aléatoire gaussien particulier vérifiant une relation d'autosimilarité matricielle. Nous avons ensuite généralisé ce modèle et introduit des champs gaussiens autosimilaires par rapport à un groupe

Avec le développement de nouvelles sources d’énergie, les technologies dédiées à son stockage ont un rôle capital. Le zirconate de Plomb (PZ de structure Pérovskite) présente un grand intérêt pour les futures capacités rapides permettant le stockage de forte densité d’énergie. Cette propriété est associée à la transition de phase ferroélectrique – anti ferroélectrique induite par le champ électrique et qui s’accompagne d’une grande capacité de stockage. Le PZ a été déposé par pulvérisation cathodique RF sur différents types de substrats et notamment le SrTiO3, les cibles sont obtenues par mélange des poudres et pressage à froid. L’étude s’est focalisée sur les effets d’interfaces entre le film et l’électrode inférieure (LaNiO3 dans notre cas), l’orientation préférentielle des films et la réalisation de films épitaxiés de PZ. La structure, la micro structure des films ainsi que leurs épaisseurs ont un impact sur les contraintes existantes dans le film et nous avons évalué ces effets sur la capacité de stockage du PZ dans la phase anti ferroélectrique. L’optimisation des propriétés des interfaces et de l’ingénierie des contraintes permettent d’améliorer la densité d’énergie stockée dans un film anti ferroélectrique. C’est une voie sérieuse pour les supers condensateurs à base de matériaux fonctionnels de type PZ
With the development of new energy resources, the advanced energy storage technologies are also becoming more and more important. Perovskite lead zirconate PbZrO3 is of great interest for future high-energy and fast-speed storage capacitors, due to the field-forced phase transition into the ferroelectric state accompanied by large charge storage. The material is deposited on SrTiO3 by RF magnetron sputtering from cold pressed target made in laboratory. The study focuses on the effect of interface between films and electrodes, preferred orientations, epitaxial strain and measuring conditions on the energy storage properties of PbZrO3-based antiferroelectric films. The improvement of interface properties and strain engineering enhance the energy storage density of antiferroelectric film, which may open a route to advance studies on PbZrO3-based antiferroelectric functional devices

Thesis (MEng) -- Stellenbosch University, 2014.
ENGLISH ABSTRACT: When desalinating brackish water by reverse osmosis (RO) or other techniques, high overall water recoveries are essential to minimize brine production and the associated disposal costs thereof. As the overall water recovery increases, concentrations of sparingly soluble salts (e.g. barium sulphate, calcium sulphate) reach levels above saturation, especially near the membrane surface, drastically increasing the scaling propensity. Antiscalants are typically dosed into the feed water to prevent such scaling during RO desalination. However, the carry-over of antiscalant into the concentrate stream can complicate subsequent salt precipitation processes that may be used to increase overall water recovery. These precipitation techniques are sometimes used to reduce the levels of super-saturation in the RO concentrate prior to a subsequent RO desalination step. The purpose of this study was to assess the feasibility of reducing calcium sulphate scaling on RO membranes, by using periodic permeate flushing when feeding a lab-scale RO unit with a supersaturated calcium sulphate solution in the absence of anti-scalant. The overall water recovery was increased by recycling the concentrate, after an intermediate de-supersaturation step. This simulated a multiple-stage RO system, typical of processes used in high-recovery acid mine drainage (AMD) treatment plants. De-supersaturation of the concentrate intermediate was achieved with direct seeded gypsum precipitation, in the absence of any antiscalant. On the membrane surface inside the membrane unit, calcium sulphate concentrations greatly exceeded saturation levels – a combined consequence of the normal concentration process and the well-known surface-based concentration polarisation phenomenon. Therefore, periodic forward-flushing of the supersaturated solution from the membrane unit was performed with permeate. In theory, the periodic flushing removes the highly concentrated layer at the membrane surface during every flush, before scaling can occur. Various flushing regimes were evaluated to assess the effectiveness of the process. A lab-scale desalination unit with a 0.106 m2 flat sheet polyamide RO membrane was designed and constructed. The unit could operate at a feed rate of 12-14 L/h and at permeate fluxes of 12-24 LMH. Super-saturated feed solutions were prepared by mixing sodium sulphate and calcium chloride dihydrate salts with demineralised water, with an initial salinity of ± 5300 mg/L TDS, corresponding to a gypsum saturation index (SIg) of 1.2 for most experiments. The total production time, net permeate production and flux decline were used to compare the flushing efficiency in different experimental runs. Initial tests showed that scaling could be prevented (when operating the unit in full recycle mode, i.e. where both concentrate and permeate were recycled to feed), at flushing frequencies between 12 and 2.4 h-1, when the membrane feed and concentrate were slightly under-saturated (SIg = 0.9) and slightly super-saturated (SIg = 1.1) respectively. However, when switching the same system to non-flushing mode after 24 hours of operation, membrane scaling occurred within 2-3 hours, as indicated by a strong decline in flux. However, when operating the system in concentrate recycle mode (i.e. permeate is withdrawn) with super-saturated feed solutions (e.g. SIg = 1.2), and thus a notably more super-saturated solution in the membrane concentrate, scaling could not be prevented (albeit delayed for some time) with intermittent permeate flushing. A fractional 25-1 factorial design was used to determine which factors had the most significant effect on total production time and permeate production rate, testing five factors: 1) flushing frequency, 2) flushing volume, 3) permeate soak time, 4) permeate flux and 5) instantaneous recovery. The ANOVA analysis showed that total production times were, not surprisingly, primarily affected by the permeate flux, where operation at 24 LMH resulted in a lower net permeate production between 3.0 - 4.2 L, compared to 7.6 - 9.7 L at 12 LMH. Higher permeate fluxes clearly resulted in higher levels of concentration polarisation at the membrane surface, thus increasing the propensity for membrane scaling. Flushing frequency and instantaneous recovery also affected the net permeate production, where 6 h-1 and 10 % were the optimal values respectively within the range of test conditions. The lowest permeate production rate resulted in the highest net permeate volume production (i.e. also longest total production time), confirmed by a least squares regression. In summary: This study showed that periodic permeate flushing could delay the membrane scaling process. However, it failed to prevent membrane scaling completely when operating the system with supersaturated calcium sulphate solutions in the absence of antiscalants. The flushing technique effectively delayed the onset of precipitation, but scaling eventually occurred if the lab-scale RO system was operated in concentrate recycle mode with oversaturated feed solutions (SIg = 1.2). Additional experiments at different cross-flow velocities during permeate flushing, while using an optimised RO test cell flow channel design, are recommended for future studies.
AFRIKAANSE OPSOMMING: Gedurende die ontsouting van brakwater deur tegnieke soos tru-osmose (TO), is ʼn maksimum herwinning van water noodsaaklik om die produksie, en die gepaardgaande kostes van verwydering, van die sout/brak neweproduk te minimeer. Soos die herwinning van water verhoog, so ook verhoog die konsentrasie van moeilik-oplosbare soute (soos bariumsulfaat, kalsiumsulfaat) in die sout konsentraat stroom, totdat die soute uiteindelik superversadiging bereik. Hierdie superversadiging gebeur veral naby die membraanoppervlak, waar dit lei tot ʼn verhoogde kans van presipitasie en skaalvorming. Om dit te voorkom word die voerwater na ʼn TO stelsel tipies gedoseer met antiskaalmiddels. Hierdie antiskaalmiddels verlaat die stelsel saam met die konsentraat, waar hulle gevolglike die presipitasie van soute bemoeilik. Presipitasie van soute uit die konsentraat kan tipies gebruik word om die vlak van superversadiging in die konsentraat te verlaag, waarna verdere TO behandeling gebruik word om selfs ʼn hoër algehele waterherwinning te bewerkstellig. Die doel van hierdie studie was om die vatbaarheid van die vermindering van kalsiumsulfaat (gips) skaalvorming in die afwesigheid van antiskaalmiddels op TO membrane te toets. Dit is bewerkstellig deur ʼn laboratoriumskaal TO eenheid te voer met ʼn superversadigde kalsiumsulfaat oplossing en die membraan periodies met skoon produkwater (permeaat) te was. Die algehele waterherwinning is verhoog deur met ʼn tussenstap die versadigingsvlak van gips in die konsentraat te verlaag, waarna dit hersirkuleer is na die voertenk. Sodoende is ʼn multi-stadium TO stelsel nageboots, soos dit tipies in hoë herwinningsaanlegte, soos met die herwinning van suur mynwater (E: acid mine drainage, AMD), gebruik word. ʼn Verlaging in superversadiging van die konsentraat in die tussenstap is behaal deur die konsentraat direk aan gipskristalle bloot te stel om presipitasie te bewerkstellig in die afwesigheid van enige antiskaalmiddels. Gedurende eksperimente het die soutkonsentrasie op die membraanoppervlak in die TO eenheid superversadigingsvlakke vêr oorskry, as gevolg van die natuurlike konsentrasie proses en die bekende konsentrasie polarisasie oppervlaksverskynsel. Om hierdie superversadiging teen te werk is periodiese saamstroom spoeling van die membraan met skoon produkwater uitgevoer. In teorie het die periodiese spoeling die hoogs gekonsentreerde oplossing van die membraan oppervlak verwyder voor skaalvorming kan plaasvind. Verskillende spoelpatrone is ondersoek om die doeltreffendheid van die spoeling te bepaal. Om die eksperimente uit te voer is ʼn laboratoriumskaal ontsoutingsaanleg met ʼn maklik verwyderbare 0.106 m2 plat-vel poli-amied TO membraan ontwerp en gebou. Die aanleg kan vloeistof voertempo’s tussen 12-24 L/h hanteer en skoon produkwater teen 12-24 LHM lewer. Die superversadigde voer oplossings, soos gebruik in die meerderheid van die eksperimentes is voorberei deur natriumsulfaat en kalsiumchloried-dihidraat soute te meng in gedemineraliseerde water, tot ʼn soutgehalte van ± 5300 mg/L TDS bereik is. Hierdie soutgehalte stem ooreen met ʼn gips versadigingsindeks (E: gypsum saturation index, SIg) van 1.2. Die skoon produkwater totale produksietyd en netto produksie, asook die membraan vloed afname, is gebruik as veranderlikes om die spoel doeltreffendheid tussen eksperimentele lopies te vergelyk. Aanvanklike toetse het getoon dat skalering voorkom is by effens onderversadigde (SIg = 0.9) en effens superversadigde (SIg = 1.1) voer oplossings met die onderskeie spoel frekwensies van 12 en 2.4 h-1, (terwyl die aanleg in algehele hersirkulasie bedryf is, m.a.w. wanneer beide die konsentraat en produkwater gedurig na die voertenk hersirkuleer word). ʼn Effens-superversadigde eksperiment is ook sonder spoeling uitgevoer vir 24 uur. In hierdie geval het skaalvorming binne twee tot drie uur gebeur, soos bevestig deur ʼn skerp afname in die membraan vloed. Skaalvorming kon nie verhoed word terwyl die aanleg bedryf word met superversadigde (SIg = 1.2) voeroplossings en slegs konsentraat hersirkulasie nie (m.a.w. skoon produkwater word opgevang), alhoewel skaalvorming vertraag kon word. Hierdie operasie het tot beduidend meer gekonsentreerde oplossings in die membraan gelei. Om te bepaal watter faktore die grootste invloed op totale produksietyd en netto produksie van skoon produkwater het, is ʼn fraksionele faktoriaalontwerp van 25-1 uitgelê wat vyf faktore toets, naamlik: 1) spoel frekwensie, 2) spoel volume, 3) skoon produkwater weektyd, 4) membraanvloed en 5) oombliklike herwinning. ʼn AVOVA analise het getoon dat totale produksietyd hoofsaaklik deur membraanvloed beïnvloed is, soos verwag kan word. Dit word gestaaf deurdat die aanleg, bedryf teen 24 LMH, slegs 3 - 4.2 L netto produkwater gelewer het, teenoor 7.6 - 9.7 L by 12 LMH. Hoër membraan vloedtempo’s het tot hoër vlakke van konsentrasie polarisasie op die membraanoppervlak gelei, wat ʼn groter neiging tot skaalvorming tot gevolg gehad het. Spoelfrekwensie en oombliklike herwinning het ʼn invloed op die netto produksie van skoon produkwater gehad, met 6 h-1 en 10 % as die onderskeie optimale waardes. ʼn Kleinstekwadraat regressie het aangedui dat die laagste produksietempo van skoon produkwater die hoogste netto produksie van skoon produkwater gelewer het, (asook die langste produksietyd). In opsomming: Hierdie studie het getoon dat gereelde spoeling met skoon produkwater die membraan skaalproses kan vertraag. Gedurende bedryf met superversadigde kalsiumsulfaat oplossings sonder enige antiskaalmiddels is daar gevind dat skaalvorming nie geheel en al vermy kon word nie. Die spoeltegniek, soos gebruik in hierdie studie, het die aanvang van skaalvorming in die laboratorium skaal TO eenheid vertraag, maar bedryf met konsentraat hersirkulasie en superversadigde oplossings (SIg = 1.2) het steeds skaal gevorm. Bykomende eksperimente teen verskeie kruisvloei snelhede gedurende die spoel stap word aanbeveel vir toekomstige studies.

碩士
國立交通大學
電控工程研究所
105
Multi-core processor have been widely used in battery-operated portable systems, desktop, and server applications, where dynamic voltage scaling (DVS) and adaptive voltage scaling (AVS) techniques are commonly employed to lower power consumption and improve thermal performance of the cores. To maximize the energy efficiency of a processor when using DVS and AVS, it is highly desirable to independently control the supply and the clock frequency for each core. As the number of cores grows, fast, cost-effective, and energy-efficient DVS and AVS schemes become prohibitively challenging to implement using off-chip switching regulators. Therefore, the fully integrated digital low-dropout regulators (DLDO) are used to achieve fast, cost-effective, and energy-efficient DVS and AVS schemes. However, the DLDO regulator has current quantization error (CQE) which produces an undesirable output voltage ripple. Moreover, the CQE of DLDO regulator is affected by process, voltage and temperature (PVT) variations, which represents the output voltage ripple of DLDO regulator depends on PVT variations. Recently, some techniques are proposed to remove CQE and thus reduce the output voltage ripple. Unfortunately, there always is a tradeoff between output voltage ripple and load regulation, which both degrade the performance of processor. As a result, the DLDO regulator with anti-PVT-variation technique is proposed in this thesis for resolve the aforementioned issues and this technique can minimize the CQE under any PVT variations and maintain good load regulation simultaneously.

AbstractA GinUE random matrix has all entries as independent standard complex Gaussians. The eigenvalue PDF can be explicitly calculated, revealing an analogy with the Boltzmann factor for a particular two-dimensional Coulomb gas. The functional form of the eigenvalue PDF leads to a determinantal structure for the general k-point correlation function. The corresponding correlation kernel admits bulk and edge scaling limits, while the density also admits a global scaling limit giving rise to an example of the circular law. Various generalisations of the GinUE permit analogous analysis. Those considered in the present chapter are the elliptic GinUE consisting of a linear combination of Hermitian and anti-Hermitian Gaussian random matrices; the induced GinUE which relates to a polar decomposition involving a rectangular generalisation of a GinUE matrix; the complex spherical ensemble of matrices $$G_1^{-1} G_2$$ G 1 - 1 G 2 , with both $$G_1,G_2$$ G 1 , G 2 GinUE matrices; the sub-block of a Haar unitary random matrix; and products of both GinUE matrices, and of truncated Haar unitary matrices. In the original paper of Ginibre [293], the diagonalisation formula $$G = V \Lambda V^{-1}$$ G = V Λ V - 1 , where $$\Lambda $$ Λ is the diagonal matrix of eigenvalues, and V is the matrix of corresponding eigenvectors which are unique up to normalisation, was used as the starting point to derive the eigenvalue PDF (1.7).

Abstract In this concluding chapter, we consider the implications of our analysis of Western overreach for the liberal order. We begin by summarizing our findings on how Western governments’ approach to international order-building has changed over the past seventy-five years and how this resulted in the anti-globalist backlash we see across the West today. We then compare and contrast our analysis to other explanations of Western overreach, anti-globalism, and domestic political fragmentation. We conclude by considering three strategies now on offer to restore Western solvency, and assess their advantages and disadvantages in light of our analysis of the liberal order: one that urges Western democracies to retrench by scaling back internationally; another that seeks to rekindle Western solidarity and support for liberal internationalism through confrontation with China and Russia; and a third strategy that seeks to bring foreign and domestic policy back into balance through a strategy of domestic renewal.

Abstract This chapter introduces the core puzzle that the book addresses: why leaders continually imagine that re-scaling the state, via either integration or secession, will solve political problems. It then provides a synopsis of the main argument: the practice of statehood à la carte is a pragmatic, anti-foundational response to the ‘problem space’ of coloniality which creates an autonomy–viability dilemma for small states in the Caribbean and the Pacific. It then situates these claims in relation to existing studies in political science and political geography, outlines the comparative interpretive approach used for the analysis, and justifies the case selection and data sources. The final section provides a brief summary of each of the subsequent chapters.

Between 2013 and 2015 the Italian Ministry of Labour and Social Policy ran an experimental anti-poverty program in 12 metropolitan areas. The program provided households with children an income support through a conditional cash transfer scheme. In order to understand how the program worked within the different local welfare systems, an ex post process evaluation was developed. Focus groups were carried out with almost ninety social workers with different professional backgrounds (social services, employment services, schools, ONGs etc.) involved in the implementation of the program. According to the analysis of the collected data, the chapter explores in particular: how social workers perceived the implementation of the program; to what extent, the insights of the evaluation process and the voices of the social workers have been taken into consideration within the scaling up of the intervention at national level.

This chapter critically assesses the forms of social and political resistance that emerged across the eight cities in our study. Building on themes introduced in chapters 1 and 2, it argues that cities serve as crucibles for a diverse set of political contestations, responses and initiatives, but they exhibit differential capacities to shape their environments. It draws particular attention to the shifting locus of resistance to austerity across communities and neighbourhoods. Our analysis and evaluation suggest that the future projection of cities as “spaces of hope” rests on the twin challenges of “scaling up” neighbourhood protests into broad and anti-systemic political projects, while reinvesting in the construction of progressive relations with the local state that open local spaces of manoeuvre to challenge national regimes of austerity.

The chapter analyzes how state media in authoritarian states manipulate information on protest. The authors develop a Russian-language dictionary and leverage the Latent Semantic Scaling (LSS) electronic content analysis technique to identify periods during which the media are more likely to portray protests as contributing to public disorder and those during which the media employ a frame that highlights citizens’ democratic right to freedom of assembly. Employing supervised machine learning, the authors analyze protest coverage in thousands of news stories that appeared in Russia’s state-controlled media during the 2011–2013 protest cycle and contrast it with coverage of protests in non-state-controlled media. Following the reelection of Vladimir Putin to his third presidential term in March 2012, a significant shift toward the disorder framing of anti-regime street activism was observed. This trend contrasts sharply with coverage of the October 2013 nationalist rallies in Moscow, which targeted migrants. The findings have implications for theorizing how autocrats manipulate protest.

Abstract Multiple organ dysfunction syndrome (MODS) is a spectrum of physiologic maladaptation in separate organs that leads to significant morbidity and mortality in intensive care unit patients. This dysfunction is rooted in the dysregulated immune response and imbalance of the pro-inflammatory and anti-inflammatory responses to a degree that homeostatic mechanisms fail to self-regulate. As a result, multiorgan failure and significant organ injury occurs. MODS is defined and quantified by assessment of injury to six vital organ systems: cardiovascular, respiratory, hepatic, renal, hematologic, and neurologic systems. Some studies have defined a numerical scaling system to quantify the degree of organ dysfunction and relative outcome measures associated. To date, the best therapy is supportive care and avoidance of further injury. It is quite evident to us that the single most effective intervention is one of primary prevention, whereby we try to prevent the failure of organs as they show manifestations of early involvement.

This chapter critically analyses the use of conceptual metaphors in selected Cameroonian newspapers articles aimed at beautifying or criticizing President Paul Biya and his aides. The selected articles covered a 2018 US-Cameroon diplomatic crisis triggered by US Ambassador's advice to Biya to relinquish power. In the light of a textual analysis of the corpus, the chapter argues that journalists and citizen journalists whose articles were considered for this study portrayed Biya and his close aides along a variety of metaphors. Positivity or negativity in the metaphors used in the media text generally depended on their authors' tones and editorial policies. The pro-government and neutral media voices (notably Cameroon Tribune and Mutations) mostly used metaphors such as nation building (representing Biya as an accomplished nation builder) and scaling (by which Biya and his aides were judged or rated high above standards). Meanwhile, anti-government media outlets (such as Cameroon Concords, Cameroon Post, Le Messager and Bareta News) used such metaphors as bestiality, scatology/garbage, theatre, oppression, transgression, and sickness/handicap among others, to criticize Biya's rule.

We report a scaling methodology for Raman molecular modulation dynamics in gas-filled anti-resonant fibers. The dephasing-gain length ratio allows complex nonlinear propagation dynamics to be reproduced with high fidelity under very different input conditions.

Abstract Scaling in the oil and gas industry is a common problem that increases expenses and reduces production rates. Traditional methods of scale prevention include chemical treatments that can be expensive and have environmental implications. Acoustic anti-scaling technology is an alternative method that has gained attention in recent years. This paper provides an overview of acoustic anti-scaling technology, including its principles, applications, and limitations. The paper concludes by discussing the potential for further research and developments in this area. This review includes various laboratory studies that evaluate the potential of using acoustic anti-scaling technology in scale removal applications. A comprehensive literature review was conducted. Acoustic anti-scaling technology was also compared to mechanical and chemical scale treatment solutions currently used by the industry. Acoustic anti-scaling involves the use of ultrasonic waves to disrupt the formation of mineral scale deposits. The ultrasonic waves create high-frequency vibrations that prevent mineral particles from attaching to surfaces and forming a solid scale layer. Typically, the frequencies used for anti-scaling are in the range of 20 kHz to 100 kHz, although some systems may use higher or lower frequencies depending on the specific equipment, composition of the fluids and the desired level of scale prevention. Acoustic anti-scaling technology has been shown to be effective in reducing scaling in various industrial systems, including desalination plants and cooling tower systems. For years, chemical and mechanical treatments have been implemented effectively to achieve scale removal and prevention. Water consumption, cost and environmental concerns have been associated with these methods. The review also highlights some limitations of acoustic anti-scaling technology. The technology is most effective in preventing the formation of soft scale, such as calcium carbonate. However, it may not be as effective in preventing hard-scale formation, such as barium sulfate. The effectiveness of the technology may also be limited by factors such as water chemistry, flow rate, and temperature. Therefore, further research is needed to optimize the technology's performance under various conditions. The paper provides novel information by analyzing the available literature on traditional scaling prevention methods and acoustic anti-scaling technology, and identifying the current state of research in this field. It also highlights the potential of acoustic anti-scaling technology as an environmentally friendly and cost-effective alternative to traditional methods of scaling prevention in the oil and gas industry.

Abstract Scale build up is a challenge faced by the O&G Industry. During production, it may cause clogging of pipes and lead to well interventions. An alternative solution increasingly studied over the years is the magnetic treatment of the fluids. This study describes the development of magnetic anti-scale accessories for deployment in offshore wells to figth scaling. Two accessories have been designed and manufactured according to the criterias defined by O&G operator. Qualification tests (vibration, shock, and hydrostatic tests) and magnetic measurements have been conducted to assess the accessories robustness and both were approved for field test. One accessory has already been successfully installed in an offshore field of Brazil and a comprehensive installation program of more accessories for the next years is being designed within PETROBRAS to better evaluate the technology efficiency.