Indiana University-Purdue University Indianapolis (IUPUI) / A new process for fabricating a nano fluidic device that can be used in medical application is developed and demonstrated. Nano channels are fabricated using a nano tip in indentation mode on AFM (Atomic Force Microscopy). The nano channels are integrated between the micro channels and act as a filter to separate biomolecules. Nano channels of 4 to7 m in length, 80nm in width, and at varying depths from 100nm to 850 nm allow the resulting device to separate selected groups of lysosomes and other viruses. Sharply developed vertical micro channels are produced from a deep reaction ion etching followed by deposition of different materials, such as gold and polymers, on the top surface, allowing the study of alternative ways of manufacturing a nano fluidic device. PDMS (Polydimethylsiloxane) bonding is performed to close the top surface of the device. An experimental setup is used to test and validate the device by pouring fluid through the channels. A detailed cost evaluation is conducted to compare the economical merits of the proposed process. It is shown that there is a 47:7% manufacturing time savings and a 60:6% manufacturing cost savings.

Indiana University-Purdue University Indianapolis (IUPUI) / Background and Rationale: As compared with glass-based ceramics, zirconia has gained considerable popularity in restorative dentistry due to its superior mechanical properties. Clinically, however, zirconia ceramics pose a significant challenge regarding the achievement of a reliable and durable bond to resin-based cements. Thus far, it has been established that zirconia bond to resin-based cements can be enhanced after different surface conditioning methods, such as airborne particle abrasion with aluminum oxide particles. Meanwhile, another major issue pertaining to bonding of ceramic restorations is related to its potential contamination before cementation. Briefly, after sandblasting and clinical try-in procedures, zirconia can be contaminated with saliva and/or blood. As with many metals, zirconium shows a strong affinity towards the phosphate group found in saliva and other fluids, which reacts with the zirconia surface and makes bonding very difficult. Recently, a new cleaning agent called Ivoclean® (Ivoclar-Vivadent), which is an alkaline suspension of zirconium oxide particles, has been introduced in the market to remove contamination from zirconia in an effort to improve bonding to resin cements. Objective: The purpose of this study was to evaluate the influence of saliva contamination and the effect of several cleaning methods, including Ivoclean on resin bond strength to zirconia. Materials and Methods: Eighty square-shaped specimens (ϕ = 12 mm x 12 mm x 3 mm) of yttria-stabilized full-contour zirconia (Diazir®, Ivoclar-Vivadent, Amherst, NY) were sectioned from zirconia blocks using a water-cooled diamond blade. Then, these specimens were embedded in acrylic resin, and their surfaces gradually finished with silicon carbide papers (600 grit to 1200 grit). The prepared zirconia surfaces were sandblasted with 50-μm aluminum oxide particles for 15 s, under 2.5 bars and from distance of 10 mm. After sandblasting the specimens were cleaned in an ultrasonic bath containing distilled water for 5 min and air-dried for 10s. All samples were equally divided into 4 groups (n = 20) according to the cleaning method. Airborne particle abraded specimens without contamination was served as the control group. Remaining groups were contaminated with saliva, and subjected to different cleaning protocols, namely: Ivoclean®, 70% isopropanol, and no treatment. Two resin cement buttons (Multilink – Ivoclar-Vivadent, Amherst, NY) were built over each zirconia surface and light-cured following the manufacturer recommendations. The influence of contamination and surface cleaning methods on ceramic bond durability were examined after 24 h on half of the samples in each group (n = 10, n = 20), and the other half (n = 10, n = 20) specimens will undergo 6000 thermocycles (TC) before shear bond testing in the universal testing machine. Conclusion of Expected Outcomes: The shear bond strength of resin cement to zirconia led to a significant improvement after cleaning with Ivoclean both immediately and after thermal aging.

Indiana University-Purdue University Indianapolis (IUPUI) / Background: All-ceramic restorations have excellent esthetic outcomes compared with other restorative materials. Lithium disilicate is classified as one of many silica-based all-ceramic materials. Currently, companies have provided single-step adhesives, known as universal adhesives, compatible with different restorative materials including lithium disilicate. Many studies have reported greater bond strengths when using a silane to treat the lithium disilicate before applying the bonding agent. Moreover, few studies were published comparing the bond strength when using the universal adhesive alone. Purpose: The objective of this study was to evaluate and compare shear bond strength of three universal adhesives to lithium disilicate ceramic restorative material. Materials and Methods: Three universal adhesive bonding agents were selected from commercially available adhesives. 408 IPS e.max CAD ceramic discs were processed, fired, and etched for 20s. The specimens were divided into six groups. The first three groups used the universal adhesive directly. The remaining three groups were treated with silane. Then, a composite resin cylinder was placed on top of the adhesive using a bonding jig. Each group was subdivided into four equal subgroups (n = 17), subjected to different aging simulation procedures: 24 h, one month with 5000 thermocycles, two months with 5000 cycles, and three months with 5000 cycles. Then, specimens were debonded using shear force by a universal testing machine (MTS). Results: Shear bond strength was greater with silane than without silane (p < 0.0001), regardless of the levels of adhesive or time. Shear bond strength was significantly greater at 24h and 1m than at 2m (p < 0.0001) or 3m (p < 0.0001) regardless of the adhesive or the presence of silane. Debonded specimens were examined under a stereomicroscope at X45 magnification to evaluate the fracture pattern. SEM was used to prove the results were considered as mixed failure. Conclusion: The optimal bonds to lithium disilicate are achieved by application of silane prior to application of a universal adhesive. Although the constituent silane in the universal adhesive was not effective in optimizing the resin to ceramic bond, silane should always be applied to lithium disilicate prior to bonding.

Indiana University-Purdue University Indianapolis (IUPUI) / Introduction: The resin-dentin interface undergoes degradation by endogenous matrix metalloproteinases (MMPs) after adhesive procedures. Application of several MMP inhibitors such as chlorhexidine (CHX) to the demineralized collagen dentin matrix after acid-etching has been suggested to be a successful approach to prevent degradation of the hybrid layer. Further, nanotubes (HNT) have been used as a reservoir for encapsulation and controlled delivery for several therapeutic drugs with sustained release. Therefore, HNT can be encapsulated with CHX and incorporated into dentin adhesives for the possibility of enhancing the longevity and durability of the hybrid layer. Objective: To evaluate the effect of a CHX-encapsulated nanotube-modified primer/PR and adhesive/ADH on the microtensile resin bond strength (µTBS) to dentin. Materials and Methods: A commercial adhesive and its respective primer were modified by adding CHX-encapsulated nanotubes at two distinct concentrations (10 and 20 wt.%). The experimental adhesives were evaluated by degree of conversion (DC) and viscosity. Meanwhile, only viscosity was determined for the experimental primers. The prepared HNT-encapsulated with CHX (10 and 20 wt.%) powders were incorporated into the primer and/or adhesive according to the groups: ADH (control); HNT (control); 0.2% CHX; PR+CHX10%; PR+CHX20%; ADH+CHX10%; ADH+CHX20%. Human molars were selected and autoclaved; mid-coronal dentin surfaces were exposed for bonding purposes. Dentin surfaces were etched, followed by primer and adhesive application, and restored with a resin composite. After 24 hours, the teeth were sliced into beams for µTBS testing; beams collected for each tooth were equally assigned into two testing condition groups: 24 hours and 6 months. Microtensile bond strength was tested using a universal testing machine, and the types of failure were classified as adhesive, mixed, and cohesive failure. Data from DC and viscosity tests were analyzed using one-way ANOVA. Bond strength data were analyzed by pair-wise comparisons using the Sidak method to control the overall significance level at 5% for each aging time separately. Weibull-distribution survival analysis was used to compare the differences in the microtensile bond strength results among the groups after 24 hours and 6 months. Results and Conclusion: DC analysis revealed no significant differences among adhesive groups. However, ADH group had a significantly lower viscosity than modified adhesive groups, and a significantly higher viscosity than modified primer groups. Test results of stress value (MPa) by each group for each aging time revealed no significant differences among groups after 24 hours. However, after 6-month storage, modified primer groups (PR+CHX10%, PR+CHX20%) and 0.2%CHX group showed a significant difference in µTBS compared to control groups (ADH, HNT) and modified adhesive groups (ADH+CHX10%, ADH+CHX20%) in the same aging time testing (p < 0.05). When comparing the µTBS after 24 hours and 6 months, there were no significant differences among the groups except for the ADH+CHX20% group, for which MPa values were higher after 24 hours than 6 months (p = 0.0487). In conclusion, this study has demonstrated the great potential of modified dental primers with CHX-encapsulated nanotubes in preservation of the resin-dentin bond strength over a 6-month time period. Additionally, modification of dental primers and adhesives was a successful approach that didn’t compromise the characteristics or the mechanical properties of the materials and has a promising long-term effect on resin-dentin bond strength.

With its unrivaled versatility and atom economy, olefin metathesis is arguably the most powerful catalyst methodology now known for the construction of carbon-carbon bonds. When compared to palladium-catalyzed cross-coupling methodologies, however, catalyst productivity lags far behind, even for the “robust” ruthenium metathesis catalysts. Unexpected limitations to the robustness of these catalysts were first widely publicized by reports describing the implementation of metathesis in pharmaceutical manufacturing. Recurring discussion centered on low catalyst productivity resulting from decomposition of the Ru catalysts by impurities, including ppm-level contaminants in the technical-grade solvent. Over the past 7 years, a series of mechanistic studies from the Fogg group has uncovered the pathways by which common contaminants (or indeed reagents) trigger catalyst decomposition. Two principal pathways were identified: abstraction of the alkylidene or methylidene ligand by nucleophiles, and deprotonation of the metallacyclobutane intermediate by Bronsted base. Emerging applications, however, notably in chemical biology, highlight new challenges to catalyst productivity. The first part of this thesis emphasizes the need for informed mechanistic insight as a guide to catalyst redesign. The widespread observation of a cyclometallated N-heterocyclic carbene (NHC) motif in crystal structures of catalyst decomposition products led to the presumption that activation of a C-H bond in the NHC ligand initiates catalyst decomposition. Reducing NHC bulk has therefore been proposed as critical to catalyst redesign. In experiments designed to probe the viability of this solution, the small NHC ligand IMe4 (tetramethylimidazol-2-ylidene) was added to the resting-state methylidene complexes formed in metathesis by the first- and second-generation Grubbs catalysts (RuCl2(PCy3)2(=CH2) GIm or RuCl2(H2IMes)(PCy3)(=CH2) GIIm, respectively). The intended product, a resting-state methylidene species bearing a truncated NHC, was not formed, owing to immediate loss of the methylidene ligand. Methylidene loss is now shown to result from nucleophilic attack by the NHC – a small, highly potent nucleophile – on the methylidene. Density functional calculations indicate that IMe4 abstracts the methylidene, generating the N-heterocyclic olefin H2C=IMe4. The latter is an even more potent nucleophile, which attacks a second methylidene, resulting in liberation of [EtIMe4]Cl. These findings report indirectly on the original question concerning the impact of ligand truncation. The ease with which a small, potent nucleophile can abstract the key methylidene ligand from GIm and GIIm underscores the importance of increasing steric protection at the [Ru]=CH2 site. This chemistry also suggests intriguing possibilities for efficient, selective, controlled methylidene abstraction to terminate metathesis activity while leaving the “RuCl2(H2IMes)(PCy3)” core intact. This could prove an enabling strategy for tandem catalysis applications in which metathesis is the first step. The second part of this thesis, inspired by the potential of olefin metathesis in chemical biology, focuses on the impact of hydroxide ion and water on the productivity of phosphine-free metathesis catalysts. In reactions with the important second-generation Hoveyda catalyst HII, hydroxide anion is found to engage in salt metathesis with the chloride ligands, rather than nucleophilic attack. The resulting Ru-hydroxide complex is unreactive toward any olefins larger than ethylene, while ethylene itself causes rapid decomposition. Proposed as the decomposition pathway is bimolecular coupling promoted by the strong H-bonding character of the hydroxide ligands. Lastly, the impact of the water on Ru-catalyzed olefin metathesis is examined. In a survey of normally facile metathesis reactions using state-of-the-art catalysts, even trace water (0.1% v/v) is found to be highly detrimental. The impact of water is shown to be greater at room temperature than previously established at 60 °C. Preliminary evidence strongly suggests that the mechanism by which water induces decomposition is temperature-dependent. Thus, at high temperature, decomposition of the metallacyclobutane intermediate appears to dominate, but this pathway is ruled out at ambient temperatures. Instead, water is proposed to promote bimolecular decomposition. Polyphenol resin, which can sequester water by H-bonding, is shown to offer an interim solution to the presence of trace water in organic media. These findings suggest that major avenues of investigation aimed at reducing intrinsic catalyst decomposition may likewise be relevant to the development of water-tolerant catalysts.

The prediction of material behavior and its microstructural evolution during high velocity impacts has been investigated for decades. The application of this topic can be observed in various engineering applications such as the cold spray process. Cold spray (CS) is an additive manufacturing method in which solid particles are accelerated using a low temperature supersonic inert gas flow, prior to their impact onto a substrate and adhesion/consolidation. In this process, unlike other thermal spray processes, the particles are kept well below their melting point prior to impact. This allows the CS process to be used for the manufacturing of high quality, specialized products at a low energy input. In CS, the deformation and bonding processes happen in a very short time (less than 100 ns). With the current technology, in-situ investigation is almost impossible. In this situation, numerical modeling methods are the best alternative to study the deposition process. There are several factors influencing the particle deposition, such as particle/substrate material properties, particle size, material temperature, particle velocity and so on, but it has been shown that the particle impact velocity has the major role during the deposition process. In fact, despite the type of bonding, i.e., mechanical or chemical, particle is sticking to the substrate after experiencing severe plastic deformation that occurs upon the impact at high velocities. Therefore, in order to develop the understating of the CS process, investigating the deformation behavior of material during high velocity impacts, and also bonding mechanisms involved during particle deposition must be investigated. III Although numerous studies have been done to explore the mechanisms occurring during particle deposition, the details of this process are still unclear. Therefore, the purpose of this research is to study the fundamental aspects of material behavior during the deformation and deposition processes with the aim of improving the understating of the CS process. Two different numerical approaches will be used to achieve the objective of the study, i.e., Finite Element Method (FEM) and Molecular Dynamics (MD) method. FEM will be used to study the metallic bonding occurring between the particle and the substrate. A physically based model to predict this phenomenon will be implemented into ABAQUS/Explicit FEM software. MD simulations will be performed to investigate the microstructure evolution during high velocity impacts. In order to characterize the deformation behavior of materials at a fundamental level, analysis will be focused on the basic mechanisms of plasticity and hardening in metals, i.e., the multiplication, glide and locking of dislocations, and also solid-state amorphization that happens at high strain rate deformations.

A compact laminated board can be obtained by pressing layers of veneers with no other material or substance placed between them. The process does not require the use of steam pretreatment, surface activation methods, a gastight press, friction or adhesives. It strictly involves the heat and the pressure induced by the press in the veneers. The levels of temperature, pressure and time leading to the highest bending-strength values when material factors are held constant are investigated. The objective of optimizing the process is reached using response surface methodology for modelling and analysis. The parameter interactions are found to be significant.Photography, scanning, X-ray densitometry, light microscopy and scanning electron microscopy (SEM) are the methods used to visually analyse the final product. Densification and darkening are two of the effects observed. / <p>Godkänd; 2008; 20081113 (ysko)</p>

FBC-ashes, as a waste product of a relatively new technology of combustion, so-called fluidized bed combustion, cannot be used for building materials production in contrast to fly-ashes. Problem rests in their chemical as well as their mineralogical composition. Thought it can be admitted that FBC-ash may be used for preparation of the hydraulic binder with a similar chemical and mineralogical composition, but only in a certain limit of concentration. The first part of this thesis was focused on the potentialities of fluid fly ashes utilization as hydraulic bonding material in preparation of dry mortar mixtures and the second part of works was engaged in research development of burned hydraulic binder of FBC ash. The thesis explores the conjunction between parameters of burning mode and hydraulic binder characteristics.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18146号 / 医博第3866号 / 新制||医||1002(附属図書館) / 31004 / 京都大学大学院医学研究科医学専攻 / (主査)教授 鈴木 茂彦, 教授 妻木 範行, 教授 戸口田 淳也 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18518号 / 工博第3910号 / 新制||工||1600(附属図書館) / 31404 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 澤本 光男, 教授 伊藤 紳三郎, 教授 中條 善樹 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM