Gastric acid challenge of lithium disilicate-reinforced glass-ceramics and zirconia-reinforced lithium silicate glass-ceramic after polishing and glazing-impact on surface properties

OBJECTIVES To investigate the impact of simulated gastric acid on the surface properties of lithium disilicate-reinforced glass-ceramics and zirconia-reinforced lithium silicate glass-ceramic after certain polishing and glazing procedures. MATERIALS AND METHODS Four different types of square-shaped specimens (10 × 10 × 2 mm$^{3}$, n = 13) were manufactured: lithium disilicate-reinforced glass-ceramic milled and polished (LDS-P); milled, polished, and glazed (LDS-PG); milled, glazed, and no polishing (LDS-G); and milled and polished zirconia-reinforced lithium silicate glass-ceramic (ZR-LS). Specimens were immersed in hydrochloride acid (HCl 0.06 M, pH 1.2) to simulate gastric acid irritation and stored in the acid for 96 h in 37 °C. Specimen weight, surface gloss, Vickers surface microhardness and surface roughness (R$_{a}$, R$_{q}$, with optical profilometer), and surface roughness on nanometer level (S$_{q}$, S$_{al}$, S$_{q}$/S$_{al}$, S$_{dr}$, S$_{ds}$ with atomic force microscope) were measured before and after the acid immersion. RESULTS ZR-LS specimens lost significantly more weight after acid immersion (p = 0.001), also surface microhardness of ZR-LS was significantly reduced (p = 0.001). LDS-G and LDS-PG showed significantly lower surface roughness (S$_{a}$, S$_{q}$) values compared to LDS-P before (p ≤ 0.99) and after (p ≤ 0.99) acid immersion and ZR-LS after acid immersion (p ≤ 0.99). CONCLUSIONS Gastric acid challenge affects the surface properties of lithium disilicate-reinforced glass-ceramic and zirconia-reinforced lithium silicate glass-ceramic. Glazing layer provides lower surface roughness, and the glazed surface tends to smoothen after the gastric acid challenge. CLINICAL RELEVANCE Surface finish of lithium disilicate-reinforced glass-ceramic and zirconia-reinforced lithium silicate glass-ceramic has a clear impact on material's surface properties. Gastric acidic challenge changes surface properties but glazing seems to function as a protective barrier. Nevertheless, also glazing tends to smoothen after heavy gastric acid challenge. Glazing can be highly recommended to all glass-ceramic restorations but especially in patients with gastroesophageal reflux disease (GERD) and eating disorders like bulimia nervosa

Optimized multilayer coating using layer-by-layer assembly method for excellent oxygen barrier of poly(lactic acid) based film

publishedVersio

Low-cost, mass-producible nanostructured surface on flexible substrate with ultra-thin gold or silver film for SERS applications

publishedVersio

Characterization of flame coated nanoparticle surfaces with antibacterial properties and the heat-induced embedding in thermoplastic-coated paper

Silver nanoparticles deposited on surfaces can provide an antibacterial effect with potential uses in, for example, health-care settings. However, release of nanoparticles and their potential exposure to the environment is of concern. The current work demonstrates a continuous synthesis that simultaneously deposits silver nanoparticles onto plastic coated paper surface by utilizing the liquid flame spray (LFS) aerosol process. Heat from LFS is used to soften the thermoplastic paper surface, which enables partial and full embedding of the nanoparticles, thereby improving adhesion. The embedding is confirmed with atomic force and scanning electron microscopy, and the deposited silver amounts are quantified with X-ray photoelectron spectroscopy. The results suggest that embedding was more effective in PE-coated paper samples due to the lower glass transition temperature when compared to PET-coated paper samples. The antibacterial properties of the surfaces against E. coli and S. aureus were maintained and confirmed with a previously developed 'Touch-Test Method: The LFS process has the potential to be used for large-scale manufacturing of antibacterial surfaces with improved nanoparticle adhesion on appropriately chosen thermoplastic surfaces

Nanostructured polymeric surfaces for biological interfaces

In order to manufacture novel synthetic materials for use in biological applications, the continuous interactions over the materials interface must be thoroughly understood. It is difficult to develop all-encompassing descriptions of the multifaceted and dynamic character of these interactions and such conclusions elude scientists to date. Mammalian and bacterial cells react to physico-chemical properties of their surroundings. Such properties include a.o. surface energy, wetting, topography, and stiffness. Using materials with a controlled physico-chemical character, cells can be influenced through controlled interactions. Disparate responses driven by different materials have been observed — such as changes in adhesion, spreading, viability, morphology, division, and phenotype. In this work different latex polymers were used to produce nanostructured surfaces with a controllable physico-chemical character, which was profoundly parameterised. The intent was to investigate how the character of the surfaces would influence Staphylococcus aureus bacterial biofilms as well as mammalian cells, specifically human dermal fibroblasts (HDF) and cervical cancer cells (HeLa). Cellular viability as well as the content and structure of the extracellular matrix or the biomatrix were used as measures of biological responsivity. In the bacterial studies, the responses of S. aureus to the surfaces were also compared in two different assays. Surface properties, such as the peak and valley structures, influenced the viability of S. aureus and the polysaccharide contents of the bacterial biomatrix. Furthermore, these biofilms were influenced differently by the surface properties in the different assays. Another novel finding was that surface properties (and assay) can influence the S. aureus surface proteome. The amount of several virulence-associated proteins on the bacterial surface could for the first time be correlated with surface roughness parameters. Mammalian HDF and HeLa cells responded differently to the surface nanotopography and surface chemistry. The viability of HeLa cells was influenced by e.g. the surface chemical character of the surfaces, but the viability of HDF cells was not influenced. An increasing amplitude of topographical peaks and valleys both increased the HDF viability, but the viability of HeLa cells was primarily benefited by a valley-dominated surface topography. These surfaces were applied in an affordable, tailorable, paper-based planar diagnostics platform. The processability of the platform was demonstrated by using it both in a materials study and a drug screening study. In the studies, both the material and the drug were applied onto the platform with up-scalable methods. The analysis was done colorimetrically with an office scanner and a custom software. The results proved to be of comparable reliability with studies done in commercial well-plates and analysed with advanced plate readers. This work shows that by using an extensive selection of surface parameters their individual influence on cells can be decoupled. Further, it shows that significant variations in different bioresponses can be observed when cells are grown on surfaces with nanoscale topographical differences. Such surfaces can be used to develop accessible, reliable and low-cost diagnostics platforms. The knowledge obtained can be used to develop novel materials for bio-applications, e.g. biomedical surfaces, where bacterial and cellular interactions with or via the material, e.g. fomite transmission, must be controlled.--------- För att tillverka nya syntetiska material för användning i biologiska tillämpningar måste de evinnerliga interaktionerna över det biologisk-syntetiska gränssnittet förstås i grunden. Denna mångfacetterade och dynamiska samverkan gör detaljstudierna svåra att tillämpas i alla situationer, och allmänna slutledningar om samverkan mellan cell och material svåra att dra. Mammalie- och bakterieceller reagerar på omgivningens alla fysikalisk-kemiska egenskaper, så som ytenergi, vätning, topografi och styvhet, osv. Genom att tillverka material där dessa egenskaper justeras kan man kontrollera eller påverka celler. Mångskiftande materialdrivna responser har mätts hos celler — allt från ändringar i adhesion, spridning och viabilitet till morfologi-, föröknings- och fenotypsförändringar. I detta arbete har olika latexpolymerer använts för att tillverka nanostrukturerade ytor med intressant och kontrollerbar fysikalisk-kemiska karaktär, vilken parametriserades ingående. Målet var att undersöka hur variationer i ytornas fysikalisk-kemiska ytegenskaper påverkar Staphylococcus aureus biofilmer, mammalie- och bakterieceller, specifikt mänskliga hudfibroblastceller (HDF) och livmodercancerceller (HeLa) respektive. Som biologiska mått på cellernas respons användes viabilitet, samt den extracellulära matrisens eller biomatrisens struktur och innehåll. I bakteriestudierna jämfördes också S. aureus’ responser till ytorna i två olika bakterieodlingsmetoder. Ytegenskaper som t.ex. topp- och dalstrukturer påverkade S. aureus biofilmernas viabilitet och biomatrisens polysackaridinnehåll. Den inverkan som ytegenskaperna hade på biofilmerna visades även variera beroende på odlingsmetod. En ny upptäckt var också att bakteriernas ytproteininnehåll påverkades av både ytegenskaper och odlingsmetod. Mängderna av flera av dessa virulensassocierade proteiner kunde för första gången korreleras med ytråhetsparametrar. HDF- och HeLa-cellerna påverkades på sinsemellan olika sätt av ytornas nanotopografi och ytkemiska egenskaper. Exempelvis påverkades HeLa-cellernas viabilitet noterbart av ytornas kemiska karaktär, medan HDF-cellernas viabilitet påverkades ej. För de erhållna ytnanostrukturerna verkade HDF-cellerna gynnas av både dominerande topp- och dalstrukturer med högre amplitud. Dominerande dalar med ökande avstånd mellan ytstrukturer verkade däremot främst gynna HeLa-cellerna. Dessa ytor tillämpades i en förmånlig och anpassningsbar planär pappersbaserad diagnostikplattform. Plattformens processerbarhet demonstrerades genom att använda den i en materialstudie och en läkemedelsutvärderingsstudie. I bägge applicerades material och läkemedel i plattformen med metoder som lämpar sig för storskalig produktion. Analys skedde kolorimetriskt med en kontorsscanner och skräddarsydd mjukvara. När resultaten jämfördes med parallellstudier från en kommersiell plastbrunnsplatta som analyserats med konventionella, avancerade plattläsare visade sig resultaten ha jämförbar tillförlitlighet. Detta arbete visar att ett omfattande urval ytparametrar kan användas för att frikoppla olika ytegenskapers påverkan på celler. Ytterligare visas att redan topografiska skillnader på nanoskala kan driva signifikanta variationer i olika bioresponser. Dessa ytor kan användas för mycket processerbara diagnostikplattformer, som trots enkla metoder kan ge tillförlitliga resultat. Resultaten från dessa studier kan utnyttjas för att utveckla nya material för biotillämpningar, t.ex. biomedicinska ytor där bakterie- och cellinteraktioner med eller via materialet måste kontrolleras

Reducing Power Losses by Optimizing Cooling in Final Annealing of Non-Oriented Electrical Steel

Surahammars Bruks AB produces non-oriented electrical steel used in several types of motors and generators. Because of recent years exponentially growing market for electrical vehicles, non-oriented electrical steel used in electrical vehicle motors is becoming an increasingly important product. Magnetic properties of the steel are very important for the efficiency of the vehicle. After cold rolling, the steel coil is annealed, which is the final manufacturing step. After final annealing, the steel is cooled gently to avoid detrimental effects on the final product. Still, it is believed that residual stresses are created in the steel during cooling, which gives worse magnetic properties in the finished material. The purpose of this thesis is to investigate the detrimental effects from the non-optimized cooling of the coil and their effect on power losses. The second part of the work will focus on optimizing the cooling. Production trials were performed to test different cooling strategies. Magnetic measurements were performed and evaluated. Single strips were measured in the rolling direction (RD) and compared with Epstein measurements. Results showed possible improvement in power losses by using gentler cooling. Results also showed increased losses and changed loss pattern as an effect of cutting the material into single strips. Cutting the material into strips changed losses differently for RD losses compared to losses in the transverse direction (TD). These results showed the importance of understanding and improving power losses in both RD and TD.Surahammars Bruks AB tillverkar icke-orienterat elektriskt stål som används i flera olika typer av motorer och generatorer. På grund av den senaste tidens exponentiella tillväxt av marknaden för elfordon, blir icke-orienterat elektriskt stål som används i elfordonsmotorer en allt viktigare produkt. Stålets magnetiska egenskaper är mycket viktiga för fordonets effektivitet. Efter kallvalsning glödgas stålet, vilket är det sista tillverkningssteget. Efter slutglödgning kyls stålet försiktigt för att undvika skadliga effekter på slutprodukten. Ändå tror man att restspänningar skapas i stålet vid kylning, vilket ger sämre magnetiska egenskaper i det färdiga materialet. Syftet med denna avhandling är att undersöka de skadliga effekterna från den icke-optimerade kylningen av bandet och dess inverkan på effektförluster. Den andra delen av arbetet kommer att fokusera på att optimera kylningen. Produktionsförsök utfördes för att testa olika kylningsstrategier. Magnetiska mätningar utfördes och utvärderades. Skurna remsor (single strips) mättes i valsriktningen och jämfördes med Epstein-mätningar. Resultaten visade möjlig förbättring av effektförluster genom att använda skonsammare kylning. Resultaten visade också ökade förluster och förändrat förlustmönster som en effekt av att materialet klipps i remsor. Att klippa materialet i remsor förändrade förlusterna annorlunda för de som klipptes i valsriktningen jämfört med de som klipptes tvärs valsriktningen. Dessa resultat visade på vikten av att förstå och förbättra effektförlusterna både i valsriktningen och tvärs valsriktningen

Reducing Power Losses by Optimizing Cooling in Final Annealing of Non-Oriented Electrical Steel

Surahammars Bruks AB produces non-oriented electrical steel used in several types of motors and generators. Because of recent years exponentially growing market for electrical vehicles, non-oriented electrical steel used in electrical vehicle motors is becoming an increasingly important product. Magnetic properties of the steel are very important for the efficiency of the vehicle. After cold rolling, the steel coil is annealed, which is the final manufacturing step. After final annealing, the steel is cooled gently to avoid detrimental effects on the final product. Still, it is believed that residual stresses are created in the steel during cooling, which gives worse magnetic properties in the finished material. The purpose of this thesis is to investigate the detrimental effects from the non-optimized cooling of the coil and their effect on power losses. The second part of the work will focus on optimizing the cooling. Production trials were performed to test different cooling strategies. Magnetic measurements were performed and evaluated. Single strips were measured in the rolling direction (RD) and compared with Epstein measurements. Results showed possible improvement in power losses by using gentler cooling. Results also showed increased losses and changed loss pattern as an effect of cutting the material into single strips. Cutting the material into strips changed losses differently for RD losses compared to losses in the transverse direction (TD). These results showed the importance of understanding and improving power losses in both RD and TD.Surahammars Bruks AB tillverkar icke-orienterat elektriskt stål som används i flera olika typer av motorer och generatorer. På grund av den senaste tidens exponentiella tillväxt av marknaden för elfordon, blir icke-orienterat elektriskt stål som används i elfordonsmotorer en allt viktigare produkt. Stålets magnetiska egenskaper är mycket viktiga för fordonets effektivitet. Efter kallvalsning glödgas stålet, vilket är det sista tillverkningssteget. Efter slutglödgning kyls stålet försiktigt för att undvika skadliga effekter på slutprodukten. Ändå tror man att restspänningar skapas i stålet vid kylning, vilket ger sämre magnetiska egenskaper i det färdiga materialet. Syftet med denna avhandling är att undersöka de skadliga effekterna från den icke-optimerade kylningen av bandet och dess inverkan på effektförluster. Den andra delen av arbetet kommer att fokusera på att optimera kylningen. Produktionsförsök utfördes för att testa olika kylningsstrategier. Magnetiska mätningar utfördes och utvärderades. Skurna remsor (single strips) mättes i valsriktningen och jämfördes med Epstein-mätningar. Resultaten visade möjlig förbättring av effektförluster genom att använda skonsammare kylning. Resultaten visade också ökade förluster och förändrat förlustmönster som en effekt av att materialet klipps i remsor. Att klippa materialet i remsor förändrade förlusterna annorlunda för de som klipptes i valsriktningen jämfört med de som klipptes tvärs valsriktningen. Dessa resultat visade på vikten av att förstå och förbättra effektförlusterna både i valsriktningen och tvärs valsriktningen

Characterization of phases in Argon Oxygen Decarburization slag

Slag is an important part of steelmaking with the AOD (Argon Oxygen Decarburization) process. In this work the focus was on developing a methodology for characterizing phases in slagsamples obtained after decarburization, reduction and desulphurization. Six samples from two heats, or batches, (heat A and B) were prepared by baking in Bakelite and polishing. These were analysed in SEM (Scanning Electron Microscope), with BSE (Backscattered Electrons) and EDS (Energy Dispersive XraySpectroscopy). Images from BSE were then processed inImageJ with a denoise method for advanced fraction analysis. Average composition for each noticed phase analysed with EDS is presented in element tables. A systematic portraying of the cross section was performed on samples from heat B. This gave a more in-depth composition and fraction analysis. Due to the nature of slag, scratches were often induced during polishing.The negative effect of these scratches could be reduced with the denoise method in the fraction analysis. There are three main phases in each stage of the AOD process with similar composition and structure between the two heats. Results showed the importance of measuring different zones of the slag due to its heterogeneity. More specifically, at least four random images from the cross section were required for accurate fraction analysis of samples after decarburization. Overall, the methodology for characterization was sufficient for samples after decarburization and desulphurization.Slagg är en viktig del av ståltillverkning med AOD-processen (Argon Oxygen Decarburization). Fokus  i  detta  arbete  var  att  utveckla  en  metod  för  att  karakterisera  faser  i  slaggprover erhållna  efter  avkolning,  reduktion  och  avsvavling.    Sex  prover  från  två  batcher  (batch  A och B) förbereddes genom bakning i bakelit och polering.  Dessa prover analyserades i SEM (Svepelektronmikroskop),  med  BSE  (Backscattered  Electrons)  och  EDS (Energy Dispersive X­ray Spectroscopy).  Bilder från BSE bearbetades sedan i ImageJ med en denoise-­metod för avancerad fraktionsanalys.  Genomsnittlig sammansättning för varje fas analyserad med EDS presenteras i elementtabeller. En systematisk undersökning av heterogenitet hos slagg utfördes på prover från batch B. Detta gav en mer noggrann komposition och fraktionsanalys. På grund av slaggens karaktär uppkom ofta repor under poleringen. Den negativa effekten av dessa repor kunde minskas med denoise-­metoden i fraktionsanalysen. Det finns tre huvudfaser i varje steg i AOD-­processen med liknande sammansättning och struktur för de två batcherna.  Resultaten visade betydelsen av att mäta slaggprovet i olika zoner på grund av dess heterogenitet.  Mer specifikt krävdes minst fyra slumpmässiga bilder från tvärsnittet för noggrann fraktionsanalys av prover efter avkolning. Sammantaget var metoden för karaterisering av slagger tillräcklig för prover efter avkolning och avsvavling

Electro-Optical Gas Sensor Consisting of Nanostructured Paper Coating and an Ultrathin Sensing Element

This work describes the use of a paper substrate for electro-optical detection of toxic hydrogen sulfide (H2S) gas. For electrical detection, a chemiresistive type of gas sensor was developed. Ultrathin gold film electrodes (UTGFE) were produced by physical vapor deposition of gold on nanostructured latex-coated paper substrate. The gas-sensing film was deposited on the electrodes by inkjet printing. The sensing films were characterized by atomic force microscopy, X-ray photoelectron spectroscopy and conductometry. The sensing films showed more than seven orders of magnitude change in resistance when exposed to as low as 1 part per million (ppm) H2S gas at room temperature. Besides resistive response, the change in color of the sensing films was studied on a paper substrate, both as a function of print density of the sensing material and H2S concentration. For quantification of the analyte the red, green and blue color deconvolution was performed on the pictures of the paper strip indicator using an open source software. A clear response was obtained from the blue channel. The inexpensive disposable color strips produced on the paper substrate can be used for qualitative and quantitative detection (as low as 1.5 ppm) of H2S gas

Electro-Optical Gas Sensor Consisting of Nanostructured Paper Coating and an Ultrathin Sensing Element

This work describes the use of a paper substrate for electro-optical detection of toxic hydrogen sulfide (H2S) gas. For electrical detection, a chemiresistive type of gas sensor was developed. Ultrathin gold film electrodes (UTGFE) were produced by physical vapor deposition of gold on nanostructured latex-coated paper substrate. The gas-sensing film was deposited on the electrodes by inkjet printing. The sensing films were characterized by atomic force microscopy, X-ray photoelectron spectroscopy and conductometry. The sensing films showed more than seven orders of magnitude change in resistance when exposed to as low as 1 part per million (ppm) H2S gas at room temperature. Besides resistive response, the change in color of the sensing films was studied on a paper substrate, both as a function of print density of the sensing material and H2S concentration. For quantification of the analyte the red, green and blue color deconvolution was performed on the pictures of the paper strip indicator using an open source software. A clear response was obtained from the blue channel. The inexpensive disposable color strips produced on the paper substrate can be used for qualitative and quantitative detection (as low as 1.5 ppm) of H2S gas