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The development of microneedles that penetrate the skin barrier, but are small enough not to stimulate nerves, has the potential to deliver drugs across skin in a painless way. Controlled injection by convective flow into skin using hollow microneedles, however, has remained a challenge. To address this challenge, the goals of this study were (i) to provide experimental measurements coupled with numerical simulations to quantitatively describe fluid mechanics of flow within microneedles over a range of experimental conditions and needle geometries, (ii) to demonstrate and study the effects of diffusion-based delivery of insulin to diabetic rats in vivo using solid and hollow microneedles and (iii) to determine the effect of experimental parameters on microinfusion through hollow microneedles into skin to optimize drug delivery protocols and identify rate-limiting barriers to flow. Experimentally, we quantified the relationship between pressure drop and flow rate through microneedles as a function of fluid viscosity and microneedle length, diameter, and cone half-angle. Microneedle tip diameter and taper angle were the primary controlling parameters for flow through conically tapered microneedles as shown by numerical simulations. Flow rates over a range of 1.4 56 l/s were achieved through microneedles (in the absence of skin) with pressure drops in the range of 4.6 196.5 kPa. This work also studied the use of solid and hollow microneedle arrays to insert into the skin of diabetic animals for transdermal delivery of insulin. Blood glucose levels dropped by as much as 80% in diabetic rats in vivo. Larger drops in blood glucose level and larger plasma insulin concentrations were shown due to higher donor solution insulin concentration, shorter microneedles insertion time and fewer repeated insertions. The final scope of this work was to determine the effect of microneedle geometry and infusion protocols on microinfusion flow rate into skin in vitro. Infusion flow rates ranged from 21 to 1130 l/h was demonstrated using glass microneedles. The presence of a bevel at the microneedle tip, larger retraction distance and insertion depth, larger infusion pressure and the presence of hyaluronidase led to larger infusion flow rates.

Nowadays, the bevel gears are widely applied in the industry for the intersected-axial transmission system. But the applications of the bevel gears are mostly limited to the usage of involute bevel gears. In this thesis, the bevel gear with circular-arc tooth profiles is derived by using general theorem of conjugate surfaces, coordinate transformation, constrained meshing equation, and spherical trigonometry. According to the bevel gears with circular-arc tooth profile derived above, the analyses and discussions of the interference are proposed. The interference situation is detected by applying the phase lead-lag concept while circular-arc curve is moving on the spherical cross-section. Furthermore, the ideal conditions to avoid occurrence of interference are proposed. Design charts for the maximum values of tooth profile angle are also constructed as a reference for designers. The 3D solid models of the bevel gear with circular-arc tooth profiles are constructed by using the computer software (Pro/E). Finally, the transmission ability is verified through the computer animation using CAE software (Visual Nastran). It is believed that the mathematical models and design method developed in the thesis will provide a useful foundation for the further studies.

The bevel gears have been widely used for the intersected-axial transmission system for a long time. But mostly them are limited in the category of involute tooth profiles. It is believed that bevel gears with circular-arc tooth profile, similar to the Wildhaber-Novikov circular-arc helical gears, will improve the load capacity of the gear set. The bevel gears with circular-arc tooth profiles was firstly proposed by Kuo and Tsai in 2001. Although these new type of bevel gears can increase the load capacity of transmission, the expensive manufacturing process is still the problem. In this paper, the design parameters of bevel gear with circular-arc profiles developed by Kuo and Tsai are modified. Bevel gear set with spiral point contact path is developed. This improvement makes it possible to manufacturing the newly developed bevel gears in just a simple milling or/and grinding process with circular cutting edges. The manufacturing process is then cost down quit a lot. A method for checking the gear interference is also proposed. Finally, the 3D solid models of the bevel gear with circular-arc tooth profiles as well as the grinding wheel are constructed by using the computer software ¡§Pro/E¡¨. It is believed that the mathematical models and the design method developed in the thesis will provide a useful foundation for the further studies.

Thesis (M.S.)--Ohio University, March, 1998. / Title from PDF t.p.

Orientador: Aparecido Carlos Gonçalves / Resumo: O medo da dor relacionada à injeção é um empecilho à terapia de injetáveis. As injeções hipodérmicas são motivos de grande ansiedade e de reduzida adesão à aplicação subcutânea de insulina para o controle glicêmico em diabéticos ou no tratamento da esclerose múltipla, aumentando o risco de complicações e mortalidade. Neste trabalho foi analisado como algumas das características da agulha podem influenciar a sensação de dor na injeção. Mediu-se o esforço de penetração de agulhas em um tecido artificial (modelo substituto da pele), para diferentes diâmetros de cânula, rugosidade, profundidade de penetração, lubrificação e ângulos do bisel da ponta perfurante. Este estudo visou encontrar alternativas para facilitar a aplicação e a autoaplicação de injeções hipodérmicas, aumentando a segurança e conforto, diminuindo a intensidade da dor percebida pelo paciente. Para isso, analisou-se no projetor de perfil e no MEV o bisel de agulhas usadas repetidas vezes para verificar a perda do perfil ou a formação de rebarbas que possam dificultar a penetração ou traumatizar o tecido durante o reuso de agulhas. Também foi analisado sob o ponto de vista mecânico, o que pode ser feito para prevenir que as agulhas usadas na aplicação subcutânea não atinjam inadvertidamente o músculo. O maior esforço de penetração observado nas agulhas com maior ângulo do bisel é responsável pela percepção de dor do paciente. / Mestre

Submitted by SIDNEI CAVASSANA null (sidnei5333@gmail.com) on 2017-09-16T17:06:01Z No. of bitstreams: 1 Mestrado Sidnei versão Final.pdf: 4006618 bytes, checksum: 3e1f03fc6f46516ae312a5bc3c98f9bb (MD5) / Approved for entry into archive by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-09-19T18:25:30Z (GMT) No. of bitstreams: 1 cavassana_s_me_ilha.pdf: 4006618 bytes, checksum: 3e1f03fc6f46516ae312a5bc3c98f9bb (MD5) / Made available in DSpace on 2017-09-19T18:25:30Z (GMT). No. of bitstreams: 1 cavassana_s_me_ilha.pdf: 4006618 bytes, checksum: 3e1f03fc6f46516ae312a5bc3c98f9bb (MD5) Previous issue date: 2017-08-01 / O medo da dor relacionada à injeção é um empecilho à terapia de injetáveis. As injeções hipodérmicas são motivos de grande ansiedade e de reduzida adesão à aplicação subcutânea de insulina para o controle glicêmico em diabéticos ou no tratamento da esclerose múltipla, aumentando o risco de complicações e mortalidade. Neste trabalho foi analisado como algumas das características da agulha podem influenciar a sensação de dor na injeção. Mediu-se o esforço de penetração de agulhas em um tecido artificial (modelo substituto da pele), para diferentes diâmetros de cânula, rugosidade, profundidade de penetração, lubrificação e ângulos do bisel da ponta perfurante. Este estudo visou encontrar alternativas para facilitar a aplicação e a autoaplicação de injeções hipodérmicas, aumentando a segurança e conforto, diminuindo a intensidade da dor percebida pelo paciente. Para isso, analisou-se no projetor de perfil e no MEV o bisel de agulhas usadas repetidas vezes para verificar a perda do perfil ou a formação de rebarbas que possam dificultar a penetração ou traumatizar o tecido durante o reuso de agulhas. Também foi analisado sob o ponto de vista mecânico, o que pode ser feito para prevenir que as agulhas usadas na aplicação subcutânea não atinjam inadvertidamente o músculo. O maior esforço de penetração observado nas agulhas com maior ângulo do bisel é responsável pela percepção de dor do paciente. / Fear of injection-related pain is a drawback to injectable therapy. Hypodermic injections are a cause for great anxiety and reduced adherence to the subcutaneous application of insulin for glycemic control in diabetics or in the treatment of multiple sclerosis, increasing the risk of complications and mortality. In this work, it was analyzed how some of the characteristics of the needle can influence the sensation of pain in the injection. The needle penetration effort was measured in an artificial tissue (substitute skin model) for different cannula diameters, roughness, depth of penetration, lubrication and angles of the perforating tip bevel. This study aimed to find alternatives to facilitate the application and self-application of hypodermic injections, increasing safety and comfort, reducing the pain intensity perceived by the patient. To do this, the bevel of needles used repeatedly was analyzed in the profile projector and SEM to verify the loss of the profile or the formation of burrs that could hamper the penetration or traumatize the tissue during the reuse of needles. It has also been mechanically analyzed, which can be done to prevent that the needles used in the subcutaneous application do not inadvertently reach the muscle. The greater penetration effort observed in the needles with greater angle of the bevel is responsible for the patient's perception of pain.

Objective: To assess the effect of finishing and polishing direction on the marginal adaptation of resin-based composite restorations. Methods: Forty human molars were collected and sectioned along their mesio-distal axis. Buccal and lingual enamel surfaces were flattened and a triangular preparation (0.87mm deep and 3mm wide) representing two 30° bevels was achieved. Specimens (n=20/per group) were randomly assigned in groups and restored with two resin-based composite materials: a nanofilled (Filtek Supreme Ultra)(FSU) and a microhybrid (Point4)(PT4) and two finishing/polishing techniques: a series of Sof-Lex discs (SL) and a sequence of diamond bur/dark-orange SL/rubber polishers (HiLuster). On each specimen, both margins were finished and polished with the same technique, one from the resin-based composite to the tooth structure (C-T) and the other from the tooth structure to the resin-based composite (T-C). Replicas were made for FeSEM observation (200X) and quantitative margin analysis was performed based on four defined marginal quality criteria. Comparisons were made between polishing directions (paired-samples t-test, Wilcoxon signed-rank test), between resin-based composites and between polishing techniques (two-sample t-test and Wilcoxon rank sum test) Results: Significant differences were found between polishing directions (p<0.05). Data showed more continuous margins, less marginal irregularities and less gaps with the polishing direction C-T than T-C except for one group (FSU/SL) with marginally significant difference in gaps (p=0.0537). Differences between the two resin-based composites and the two polishing techniques seemed to be dependent on certain combinations of resin-based composite, polishing technique and polishing direction. Conclusion: Within the limitations of this in vitro study, polishing from resin-based composite to tooth structure (C-T) leads to better marginal adaptation than polishing from tooth structure to resin-based composite (T-C).

Magister Scientiae Dentium - MSc(Dent) / The treatment objectives in the restoration of an endodontically treated tooth are maximum retention of post and core and to create a design in which the tooth is preserved when the restoration fails. The ferrule effect in root treated teeth requiring cast post and core has been studied extensively and has been shown to greatly improve fracture resistance (Gluskin et al 1995, Libman & Nicholls, 1995. Hemmings et al, 1991. Barkhordar et al, 1989. Rosen & Partida-Rivera, 1986). Studies have also shown that in the case of cast post and core, the longer the ferrule, the greater the fracture resistance (Libman and Nicholls, 1995). The use of the new bonding agents, composite resin cements and core materials, have led to a more conservative approach to post and core restorations. However few studies have considered the effect of different ferrule designs on prefabricated post and composite core systems (Volwiler et al 1989, Al Hazaimeh and Gutteridge 2001). There is little information as to whether the ferrule is of additional value in providing reinforcement in these restorations. This study investigated the effects of different ferrule designs on the fracture resistance of teeth incorporating prefabricated posts and composite cores. In addition teeth restored with a composite core but with no prefabricated post were included in the study to assess the necessity of a post in the restoration of endodonticallytreated teeth. Sixty extracted maxillary incisors (centrals and laterals) and carunes were randomly assigned into three groups and restored. Two groups had a prefabricated post and composite core with varying ferrule designs. A third group had a core with composite packed into the root canal but no post. All teeth were restored with cast crowns to simulate the clinical situation. A Zwick universal testing machine was used to apply compressive loads progressively on the restored teeth until failure occurred as a result of either root, tooth or post fracture. Failure loads, modes of fracture, post and core systems and tooth preparation were recorded and statistically analysed. The results showed no significant difference in the amount of force needed to break the teeth in the different groups irrespective of whether the teeth had a ferrule or not. They also showed no significant difference in the amount of force needed to break the teeth in the different groups irrespective of whether the teeth had a post or not.

Most robotic systems reported for MRI-guided prostate interventions use manual needle insertion, based on a previously acquired image, which requires withdrawing the patient from the scanner multiple times during the procedure. This makes the intervention longer, more expensive and elongating the discomfort to patient and, most importantly, less accurate due to the virtually inevitable motion of the target. As a remedy, automated needle placement methods were proposed, putting human supervision out of the control loop. This thesis presents the development of enabling technologies for human-operated in-room master-slave needle placement under real-time MRI guidance, while the patient is kept in the scanner and having the process of needle placement under continuos control of the physician. The feasibility of teleoperated needle insertion was demonstrated by developing a 1-DOF (degree of freedom) MRI-compatible master-slave system, which was integrated with a 4-DOF robot for transperineal prostate biopsy and brachytherapy. An accuracy study was conducted on a robotic system for MRI-guided prostate needle placement. Different error sources were identified and quantified. This study concluded that errors occurring during needle insertion have the most significant contribution to needle placement error. In order to compensate for these errors, teleoperated needle steering under real-time MRI guidance was proposed. A 2-DOF piezo-actuated MRI-compatible needle steering module was developed and integrated with the aforementioned 4-DOF transperineal robot, yielding a fully actuated 6-DOF (x, y, z, yaw, pitch, roll) robotic platform for MRI-guided prostate interventions. A novel MRI-compatible master robot was also developed to enable teleoperated needle steering inside the MRI room. MRI-compatible controller hardware and software were developed. A novel MRI-compatible force/torque sensor was devised using Fiber Bragg Grating for force measurement in MRI room. Phantom experiments proved the feasibility iii of teleoperated needle steering under real-time MRI guidance. A system was also developed for real-time 3D shape tracking of a bevel-tip needle with Fiber Bragg Grating sensors embedded along the needle shaft. The needle profile was overlaid on the real-time MR image, yielding real time navigation with accuracy better than 0.5 mm. The experimental system is presently being refitted for clinical safety and feasibility trials on real patients. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2013-05-30 12:26:18.732