Hybrid inorganic-polymer coatings prepared via miniemulsion process

A synthetic route was designed for the incorporation of inorganic materials within water-based miniemulsions with a complex and adjustable polymer composition. This involved co-homogenization of two inverse miniemulsions constituting precursors of the desired inorganic salt dispersed within a polymerizable continuous phase, followed by transfer to a direct miniemulsion via addition to an o/w surfactant solution with subsequent homogenization and radical polymerization. To our knowledge, this is the first work done where a polymerizable continuous phase has been used in an inverse (mini)emulsion formation followed by transfer to a direct miniemulsion, followed by polymerization, so that the result is a water-based dispersion. The versatility of the process was demonstrated by the synthesis of different inorganic pigments, but also the use of unconventional mixture of vinylic monomers and epoxy resin as the polymerizable phase (unconventional as a miniemulsion continuous phase but typical combination for coating applications). Zinc phosphate, calcium carbonate and barium sulfate were all successfully incorporated in the polymer-epoxy matrix. The choice of the system was based on a typical functional coatings system, but is not limited to. This system can be extended to incorporate various inorganic and further materials as long as the starting materials are water-soluble or hydrophilic. rnThe hybrid zinc phosphate – polymer water-based miniemulsion prepared by the above route was then applied to steel panels using autodeposition process. This is considered the first autodeposition coatings process to be carried out from a miniemulsion system containing zinc phosphate particles. Those steel panels were then tested for corrosion protection using salt spray tests. Those corrosion tests showed that the hybrid particles can protect substrate from corrosion and even improve corrosion protection, compared to a control sample where corrosion protection was performed at a separate step. Last but not least, it is suggested that corrosion protection mechanism is related to zinc phosphate mobility across the coatings film, which was proven using electron microscopy techniques.Eine neuartige synthetische Route zur Einlagerung von anorganischen Materialien in wässrige Miniemulsionen einer komplexen und variablen polymeren Zusammensetzung wurde entwickelt. Das Synthesekonzept basiert auf der Co-Homogenisierung zweier inverser Miniemulsionen, welche die Vorstufen der gewünschten anorganischen Pigmente als wässrige Lösungen, dispergiert in einer polymerisierbaren kontinuierlichen Phase enthalten. Durch die Addition einer wässrigen Lösung eines o/w Tensids und nachfolgender Homogenisierung wurde im nächsten Schritt die Bildung einer direkten Miniemulsion - welche die inverse Miniemulsion als disperse Phase enthält - induziert. Die freie radikalische Polymerisation der so gebildeten Monomertropfen resultierte in einer wässrigen Dispersion polymerer Hybrid-Nanopartikel. Diese Methode wurde im Rahmen dieser Arbeit erstmals beschrieben und zeichnet sich durch eine besondere Vielseitigkeit bezüglich der verwendbareren anorganischen Pigmente und der polymerisierbaren Komponenten aus. Es konnte gezeigt werden, dass sich Zinkphosphat, Calciumcarbonat und Bariumsulfat erfolgreich in Polymer-Epoxy Matrices einbetten ließen. Hierbei stellt die Verwendung der Mischung aus Vinylmonomeren und Epoxyharz (etabliert in Beschichtung-Anwendungen) als kontinuierliche Phase in der inversen Miniemulsion ein neuartiges Konzept dar. Das untersuchte System basiert auf einer typischen, etablierten Materialkombination, welche in der Beschichtungsindustrie Anwendung findet. Darüberhinaus lässt sich jedoch das hier entwickelte Verfahren zur Einbettung von speziellen Materialien in polymere Matrices auf eine Vielzahl von (anorganischen) Komponenten erweitern. Die einzige Voraussetzung hierbei ist die Wasserlöslichkeit der entsprechenden Vorstufen. rnDie synthetisierten wässrigen Dispersionen der Hybrid-Nanopartikel aus Zinkphosphat in einer polymeren Matrix wurden in weiteren Untersuchungen dazu verwendet Probenkörper aus Stahl zu beschichten. Hierzu wurde in Analogie zu industriellen Beschichtungsverfahren, der sogenannte autodeposition Prozess verwendet. Hierbei stellt die Verwendung einer wässrigen Dispersion polymerer Partikel, welche eingebettete Zinkphosphat-Pigmente beinhalten, eine Neuerung dar. rnDie beschichteten Stahlplatten wurden bezüglich ihrer Korrosionsbeständigkeit mittels eines Salz-Sprüh Verfahrens untersucht. Diese Untersuchungen zeigten, dass die Beschichtungen mit den neuartigen Hybrid-Nanopartikeln die Korrosion erfolgreich reduzieren konnten. Im Vergleich zu etablierten Verfahren, welche auf einer Einlagerung von Zinkphosphat vor dem Aufbringen einer polymeren Schicht basieren, zeigten die untersuchten Proben eine bessere Korrosionsbeständigkeit. Anhand von rasterelektronenmikroskopischen Untersuchungen konnte nachgewiesen werden, dass der zugrundeliegende Mechanismus auf einer Diffusion des Zinkphosphats durch den polymeren Film in Richtung des Stahlkörpers basiert

A system identification technique based on the random decrement signatures. Part 2: Experimental results

Identification of the system parameters of a randomly excited structure may be treated using a variety of statistical techniques. Of all these techniques, the Random Decrement is unique in that it provides the homogeneous component of the system response. Using this quality, a system identification technique was developed based on a least-squares fit of the signatures to estimate the mass, damping, and stiffness matrices of a linear randomly excited system. The results of an experiment conducted on an offshore platform scale model to verify the validity of the technique and to demonstrate its application in damage detection are presented

A system identification technique based on the random decrement signatures. Part 1: Theory and simulation

Identification of the system parameters of a randomly excited structure may be treated using a variety of statistical techniques. Of all these techniques, the Random Decrement is unique in that it provides the homogeneous component of the system response. Using this quality, a system identification technique was developed based on a least-squares fit of the signatures to estimate the mass, damping, and stiffness matrices of a linear randomly excited system. The mathematics of the technique is presented in addition to the results of computer simulations conducted to demonstrate the prediction of the response of the system and the random forcing function initially introduced to excite the system

Optimising novel dental composites for paediatric patients

Since amalgam use to restore children`s teeth is no longer an option due to Minamata agreement and with the absence of a viable strong and easy to apply material, a need for a novel restoration has become essential. The aim of this research was therefore to develop a novel children’s composite that would enable a simpler and pain-free restorative method and be a feasible alternative for the difficult to place resin restorations and the weak glass ionomers. The initial eight formulations studied incorporated an adhesion promoting monomer, 4META (3wt%) within a base monomer, UDMA (72wt%) combined with low shrinkage diluent monomer PPGDMA (24wt%) and the photoinitiator camphorquinone (1wt%). This was mixed with a glass powder phase at two Powder/ Liquid ratios (PLR, 5:1 or 3:1). The glass filler contained different levels of two new novel additives to enable placement on caries affected dentine following minimal tooth excavation; antibacterial PolyLysine (PLS, 5 or 2wt%) and a remineralising agent Monocalcium Phosphate monohydrate, (MCP, 8 or 4wt%). Tests were performed to determine maximum levels of active agents that could be added whilst maintaining properties that would enable compliance with composite ISO and safety requirements. Studies included light curing kinetics, interaction of cured material with water (sorption and solubility, mass and volume changes, and release of agents) and mechanical properties (Flexural strength and modulus). These studies lead to a predicted optimal formulation with PLS of 4wt%, MCPM of 8wt% and PLR 3:1. The optimal formulation was large scale manufactured and the above studies repeated. Furthermore, testing of adhesion to tooth structure by means of microleakage, adaptation to cavity walls, shear bond strength and formation of resin tags within carious dentine was assessed. Finally, the ability to precipitate minerals and inhibit enzymatic activity at the adhesion interface was tested. Results showed that the proposed formulations were stable when aged at 60ºC for 6 months and had high monomer conversion (~>65%) when light-cured for 40s even with samples of 3mm thickness. Formulations of higher PLS and MCP content also exhibited higher water sorption and solubility values due to the hydrophilicity and release of these components. This was expected and observed to reduce the early mechanical properties, but the results showed that flexural strength and modulus levelled off after 3 months of soaking cured discs in water. The flowability of the paste and the PLS and MCP content were all positive factors in achieving better penetration and resin tags formation within the collagen mesh. This collagen mesh was a standardised caries-like model which was created during this study. The final optimised formulation results showed the material to be radio-opaque. It achieved >75% monomer conversion and was mechanically strong (120MPa biaxial flexural strength and 3.5GPa modulus). The water sorption and solubility values were just higher than the ISO recommended maximum values that were set for composites of non-releasing ability. The material also outperformed commercial comparators in terms of self-etching the enamel and adapting to the sound cavity walls. Furthermore, it also formed long and extensive tags (more than 200µm long) within collagen mesh (formic acid demineralised coronal tooth slices) and naturally carious dentine. Finally, the optimised material exhibited precipitation of minerals at the adhesion interface. Tags and mineral precipitation helped explain observation of matrix metalloproteinase (MMP) inhibition at the tooth / carious dentine interface. The results were used to support applications to MHRA for clinical trials and a notified body for CE mark. In conclusion, the research presented has achieved its aim to develop a marketable material that has the potential to address problems arising with amalgam ban

Antioxidant activity of different extracts of Vitex agnus-castus (L.) and phytochemical profile

The main goal of this study was to evaluate antioxidant activity of Vitex agnus-castus aerial parts and also to investigate the main phytoconstituents in the plant extracts. Nhexane, dichloromethane, ethyl acetate and methanol 80% extract were tested for free radical scavenging activity on model reaction with stable 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). The results showed that ethyl acetate was the most active one as antioxidant agent and phytochemical analysis of the ethyl acetate extract revealed the presence of triterpenes, flavonoids, tannins, alkaloids and carbohydrates. The results suggest new chemical classes of natural antioxidant substances that could serve as selective agents for infectious diseases

MODEL MATEMATIKA UNTUK STRATEGI MENGUNGSI-RELOKASI PADA BERPELITA (Buku cERdas PEnduduk Lereng gunung apI Tergolong Aktif)

Meletusnya Gunung Merapi pada tahun 2010 mengakibatkan terhentinya aktivitas warga selama lebih dari dua minggu. Besarnya gangguan yang ditimbulkan diakibatkan jumlah material vulkanik yang telah dikeluarkan sejak erupsi pada 26 Oktober 2010 hingga penghujung tahun 2010 telah mencapai 150 juta meter kubik (Kompas.com:2010). Pemerintah menginstruksikan warga untuk mengungsi. Sayangnya, belum ada sistem pengungsian yang terkoordinir dengan baik. Selain itu, biaya transportasi pengungsian dan relokasi menjadi sangat besar. Berdasarkan uraian masalah di atas, masalah dapat dirumuskan dengan “Bagaimana menyusun rute antara lokasi pengungsian dan lokasi relokasi agar biaya transportasi relokasi minimum?” Model matematika cocok untuk mengatasi masalah ini. Model matematika adalah model yang menggunakan simbol matematika atau logika untuk menyederhankan bahkan memcahkan masalah (Maki,1973:8). Penulisan ini diawali dari pengamatan terhadap permasalahan biaya relokasi yang relatif besar. Dengan mengacu pada aturan metode ilmiah permodelan matematika, studi ini disusun. Dari studi tersebut diketahui beberapa faktor yang berpengaruh langsung pada biaya tempuh. Faktor-faktor tersebut yaitu faktor lokasi pengungsian, lokasi relokasi, efektifitas jalan, tingkat kemacetan jalan, hambatan cuaca, biaya angkutan dan satuan angkutan. Model ini bertujuan untuk mencari hubungan matematis antar faktor-faktor, sehingga dapat diprediksi biaya relokasi yang akurat dan minimum. Model ini tidak hanya berlaku untuk masalah relokasi pengungsi Merapi, tetapi juga manajemen pengungsiannya (jika diasumskan graf menjadi 2 arah). Penggunaan model dengan peta gunung berapi aktif lain (contoh: Gunung Bromo), maka model dapat kembali digunakan. Kata Kunci: Minimalisasi biaya mengungsi relokasi, Optimasi rute transportasi

Prevalence of Healthcare Associated Infections in Adults Recipients of Autologous Hematopoietic Stem Cell Transplantation in Qatar

Objective To analyze the prevalence and characteristics of Healthcare Associated Infections (HAI) in patients with hematologic malignancies who underwent Autologous Hematopoietic Stem Cell Transplantation (AHSCT) at the National Center for Cancer Care and Research (NCCCR) newly opened transplant unit in Qatar between October 2015 and October 2016 with global comparison of the bloodstream Infection (BSI) prevalence, one of the most prevalent complications after stem cell transplant. Methods The Center of Disease Control (CDC) definitions for laboratory-confirmed bloodstream infection (BSI), modified criteria for pneumonia and hospital-acquired infections were used. Statistical analysis was done using STATA version14. The entire healthcare associated infections (HAI) and other variables were described using means, proportions and 95% confidence intervals. Meta-Analysis of Observational Studies in Epidemiology guidelines was applied in conducting the meta-analysis. The systematic search in English was done in PubMed from 1970 (date of stem cell transplant kick off) to 2016. Inclusion was restricted to human hematology studies that included AHSCT. Statistical calculations allowing an accurate estimation of the prevalence were calculated using MetaXl version 5.3. The data extraction for both studies was done independently by two reviewers. Results Out of the sixteen patients, three developed infection leaving the overall infection rate to 18.75%. Chemotherapy induced gastroenteritis was documented in 68.7% of the cases, chemotherapy induced mucositis was documented in 43.7% of the cases. Most of the infections occurred during neutropenia (92.3%) and 69.2% of them during febrile neutropenia. No gastroenteritis was microbiologically confirmed, all were clinically documented infections. Bacterial infections accounted for 12.5% (2/16 cases) one upper respiratory tract infection and one urinary tract infection. Whereas viral infections, pneumonia and urinary tract infections were each 6.25% (1/16 cases respectively). There was no prevalence of bloodstream infection or central line associated bloodstream infection for any of the patients. As for the meta-analysis, the aggregated results were studied in the 10 included studies. Significant heterogeneity was noted among the studies (I2 = 99%; P = 0.0001), the pooled prevalence of blood stream infection among 55789 AHSCT patients from the ten studies was 6%, 95% CI: 0, 33. Conclusion This study provides original baseline data about the prevalence of HAI among AHSCT in NCCCR. These findings will be used for additional evaluation of the influence of infection prevention and control measures and therapeutic plans for these patients. They will also contribute to the enhancement of the quality of care in NCCCR, mainly in the hematopoietic stem cell transplant unit (HSCT) through the proper implementation of the infection control standards and proper implementation of antimicrobial stewardship program

Visual Impairment and Majoring in English as a Foreign Language.

This study is intended to investigate visual impairment and majoring in English as a foreign language (EFL). A qualitative approach is adopted to explore the experiences of five visuallyimpaired Palestinians during their BA program in EFL. Despite the difficulties they faced while studying at the university, the five participants managed to excel in a major that is not common to the visually-impaired in Palestine. Four key themes are highlighted in this study: why the participants chose to major in English, what challenges they faced during their BA program, how they coped with these challenges and what final results they obtained, and their recommendations for better inclusion of the visually-impaired in the Palestinian higher education context. As there is no specific research addressing the issue of visual impairment and majoring in EFL at the university level, this study is intended to fill a gap in the literature

The acquisition of the English causative-inchoative alternation by Arabic native speakers

This study is an investigation of Arabic native speakers’(ANSs) acquisition of the English causative-inchoative alternation (eg Tom broke the vase vs. The vase broke). Emphasis is placed on the relationship between English proficiency, language transfer, and Universal Grammar mechanisms in ANSs’ interlanguage representations. Four central research questions guide the study:(1) Does the English causative-inchoative alternation pose a learnability problem for ANSs?(2) Do ANSs distinguish between unaccusative and unergative verbs in English?(3) Are there L1 transfer effects on ANSs’ acquisition of the English causative-inchoative alternation?(4) Are there differences across English proficiency levels with respect to the answers to questions 1–3? To address these questions, an acceptability judgment and correction task was administered to a total of 119 ANSs (from the Gaza Strip, Palestine) of different