Investigation of capacitive discharge heating of metallic glasses

In recent years, the discovery of bulk metallic glasses with exceptional properties has generated much interest. One of their most intriguing features is their capacity for viscous flow above the glass transition temperature. This characteristic allows metallic glasses to be formed like plastics at modest temperatures. However, crystallization of supercooled metallic liquids in the best bulk metallic glass-formers is much more rapid than in most polymers and silicate glass-forming liquids. The short times to crystallization impairs experimentation on and processing of supercooled glass-forming metallic liquids. A technique to rapidly and uniformly heat metallic glasses at rates of 10⁵ to 10⁶ kelvin per second is presented. A capacitive discharge is used to ohmically heat metallic glasses to temperatures in the super cooled liquid region in millisecond time-scales. By heating samples rapidly, the most time-consuming step in experiments on supercooled metallic liquids is reduced orders of magnitude in length. This allows for experimentation on and processing of metallic liquids in temperature ranges that were previously inaccessible because of crystallization.

A variety of forming techniques, including injection molding and forging, were coupled with capacitive discharge heating to produce near net-shaped metallic glass parts. In addition, a new forming technique, which combines a magnetic field with the heating current to produce a forming force, was developed. Viscosities were measured in previously inaccessible temperature ranges using parallel plate rheometry combined with capacitive discharge heating. Lastly, a rapid pulse calorimeter was developed with this technique to investigate the thermophysical behavior of metallic glasses at these rapid heating rates.

Injection laryngoplasty with autologous fascia for treatment of unilateral vocal fold paralysis

The purpose of this dissertation was to study the applicability of minced autologous fascia graft for injection laryngoplasty of unilateral vocal fold paralysis (UVFP). Permanence of augmentation and host versus graft tissue reactions were of special interest. The topic deals with phonosurgery, which is a subdivision of the Ear, Nose and Throat-speciality of medicine. UVFP results from an injury to the recurrent or the vagal nerve. The main symptom is a hoarse and weak voice. Surgery is warranted for patients in whom spontaneous reinnervation and a course of voice therapy fails to improve the voice. Injection laryngoplasty is a widespread surgical technique which aims to restore glottic closure by augmenting the atrophied vocal muscle, and also by turning the paralyzed vocal fold towards midline. Currently, there exists a great diversity of synthetic, xenologous, homologous, and autologous substances available for injection. An autologous graft is perfect in terms of biocompatibility. Free fascia grafts have been successfully used in the head and neck surgery for decades, but fascia had not been previously applied into the vocal fold. The fascia is harvested from the lateral thigh under local anesthesia and minced into paste by scissors. Injection of the vocal fold is performed in laryngomicroscopy under general anesthesia. Three series of clinical trials of injection laryngoplasty with autologous fascia (ILAF) for patients with UVFP were conducted at the Department of Otorhinolaryngology of the Helsinki University Central Hospital. The follow-up ranged from a few months to ten years. The aim was to document the vocal results and possible morbidity related to graft harvesting and vocal fold injection. To address the tissue reactions and the degree of reabsoprtion of the graft, an animal study with a follow-up ranging from 3 days to 12 months was performed at the National Laboratory Animal Center, University of Kuopio. Harvesting of the graft and injection was met with minor morbidity. Histological analysis of the vocal fold tissue showed that fascia was well tolerated. Although some resorption or compaction of the graft during the first months is evident, graft volume is maintained well. When injected deep and laterally into the vocalis muscle, the fascia graft allows normal vibration of the vocal fold mucosa to occur during phonation. Improvement of voice quality was seen in all series by multiple objective parameters of voice evaluation. However, the vocal results were poor in cases where the nerve trauma was severe, such as UVFP after chest surgery. ILAF is most suitable for correction of mild to moderate glottic gaps related to less severe nerve damage. Our results indicate that autologous fascia is a feasible and safe new injection material with good and stable vocal results. It offers a practical solution for surgeons who treat this complex issue.

Spray characterization of straight vegetable oils at high injection pressures

We present results of high pressure spray characterization of Straight Vegetable Oils (SVOs) which are potential diesel fuel substitutes. SVO sprays are visualized at high injection pressures (up to 1600 bar) to study their atomization characteristics. Spray structure studies are reported for the first time for Jatropha and Pongamia vegetable oils, under atmospheric conditions. Jatropha and Pongamia SVO sprays are found to be poorly atomized and intact liquid cores are observed even at an injection pressure of 1600 bar. Non-Newtonian behavior of Jatropha and Pongamia oil is shown to be the reason for observed spray structure. (C) 2012 Elsevier Ltd. All rights reserved.

Effect of Inlet Jet injection angle on a calandria based reactor-An investigation with numerical analysis of heat and mass transfer for an optimum reactor design

Heat and mass transfer studies in a calandria based reactor is quite complex both due to geometry and due to the complex mixing flow. It is challenging to devise optimum operating conditions with efficient but safe working range for such a complex configuration. Numerical study known to be very effective is taken up for investigation. In the present study a 3D RANS code with turbulence model has been used to compute the flow fields and to get the heat transfer characteristics to understand certain design parameters of engineering importance. The angle of injection and of the coolant liquid has a large effect on the heat transfer within the reactor.

Performance of a Supersonic Model Combustor using Vaporized Kerosene Injection

Characteristics of supersonic combustion by injecting kerosene vapor into a Mach 2.5 crossflow at various preheat temperatures and pressures were investigated experimentally. A two-stage heating system has been designed and tested, which can prepare heated kerosene of 0.8 kg up to 820 K at pressure of 5.5 Mpa with minimum/negligible fuel coking. In order to simulate the thermophysical properties of kerosene over a wide range of thermodynamic conditions, a three-component surrogate that matches the compound class of the parent fuel was employed. The flow rate of kerosene vapor was calibrated using a sonic nozzle. Computed flow rates using the surrogate fuel are in agreement with the experimental data. Kerosene jets at various preheat temperatures injecting into both quiescent environment and Mach 2.5 crossflow were visualized. It was found that at injection pressure of 4 Mpa and preheat temperature of 550 K the kerosene jet was completely in vapor phase, while keeping almost the same penetration depth as compared to the liquid kerosene injection. Supersonic combustion tests were also carried out to compare the combustor performance for the cases of vaporized kerosene injection, liquid kerosene injection, and effervescent atomization with hydrogen barbotage, under the similar stagnation conditions. Experimental results demonstrated that the use of vaporized kerosene injection leads to better combustor performance. Further parametric study on vaporized kerosene injection in a supersonic model combustor is needed to assess the combustion efficiency as well as to identify the controlling mechanism for the overall combustion enhancement.

Improved Mechanical Properties of Compatibilized Polypropylene/Polyamide-12 Blends

Compatibilized blends of polypropylene (PP) and polyamide-12 (PA12) as a second component were obtained by direct injection molding having first added 20% maleic anhydride-modified copolymer (PP-g-MA) to the PP, which produced partially grafted PP (gPP). A nucleating effect of the PA12 took place on the cooling crystallization of the gPP, and a second crystallization peak of the gPP appeared in the PA12-rich blends, indicating changes in the crystalline morphology. There was a slight drop in the PA12 crystallinity of the compatible blends, whereas the crystallinity of the gPP increased significantly in the PA12-rich blends. The overall reduction in the dispersed phase particle size together with the clear increase in ductility when gPP was used instead of PP proved that compatibilization occurred. Young's modulus of the blends showed synergistic behavior. This is proposed to be both due to a change in the crystalline morphology of the blends on the one hand and, on the other, in the PA12-rich blends, to the clear increase in the crystallinity of the gPP phase, which may, in turn, have been responsible for the increase in its continuity and its contribution to the modulus.

The influence of injection conditions and soil types on soil improvement by microbial functions

Research has begun on Microbial Carbonate Precipitation (MCP), which shows promise as a soil improvement method because of its low carbon dioxide emission compared to cement stabilized agents. MCP produces calcium carbonate from carbonates and calcium in soil voids through ureolysis by "Bacillus Pasteurii". This study focuses on how the amount of calcium carbonate precipitation is affected by the injection conditions of the microorganism and nutrient salt, such as the number of injections and the soil type. Experiments were conducted to simulate soil improvement by bio-grouting soil in a syringe. The results indicate that the amount of precipitation is affected by injection conditions and soil type, suggesting that, in order for soil improvement by MCP to be effective, it is necessary to set injection conditions that are in accordance with the soil conditions. © 2011 ASCE.

Injection, Transport, Absorption and Phosphorescence Properties of a Series of Blue-Emitting Ir(III) Emitters in OLEDs: a DFT and Time-Dependent DFT Study

Quantum-chemistry methods were explored to investigate the electronic structures, injection and transport properties, absorption and phosphorescence mechanism of a series of blue-emitting Ir(III) complexes {[(F-2-ppy)(2)Ir(pta -X/pyN4)], where F-2-ppy = (2,4-difluoro)phenylpyridine; pta = pyridine-1,2,4-triazole; X = phenyl(1); p-tolyl (2); 2,6-difluororophenyl (3); -CF3 (4), and pyN4 = pyridine-1,2,4-tetrazolate (5)}, which are used as emitters in organic light-emitting diodes (OLEDs). The mobility of hole and electron were studied computationally based on the Marcus theory. Calculations of Ionization potentials (IPs) and electron affinities (EAs) were used to evaluate the injection abilities of holes and electrons into these complexes.

A randomised study of two training programmes for general practitioners in the techniques of shoulder injection

Training on patients in addition to conventional mannequins increased GPs shoulder injection activity and their level of confidence.Hospital injection clinicsa may provide a suitable setting in which to train GPs interested in developing their shoulder joint injection skills

A two compartment in vitro release model for the testing of HIV microbicide formulations

BACKGROUND: In vitro release testing of vaginal formulations is usually performed in a one-compartment model (OCM) where the release medium, usually comprising pH-adjusted water, an aqueous surfactant solution or a solvent-water solution, provides sink conditions throughout the release experiment. Although this model is useful in evaluating the effect of formulation parameters upon release, it rarely reflects in vivo conditions. Here we report use of a two-compartment diffusion cell model (TCM, comprising a small volume donor, a large volume receptor, and separated by a model epithelial membrane) to more closely mimic in vivo vaginal release and tissue absorption following administration of a UC781 vaginal ring.

METHODS: Macaque-sized matrix silicone elastomer vaginal rings containing 100mg UC781 were prepared by injection molding, and in vitro release testing performed using both OCM (20mL simulated vaginal fluid, SVF) and TCM (5mL SVF in donor cell and variable quantities of Tween 80; silicone elastomer membrane; 100mL 3:2 ethanol/water in receptor cell). In the TCM, drug levels were measured by HPLC in both donor and receptor cells, representing fluid and tissue levels respectively. Rings containing 100mg UC781 and 10% w/w Tween 80 were also manufactured and tested.

RESULTS: The amount of UC781 released from rings was significantly influenced by the choice of release model. Greatest release (56mg/14 days) was measured in the ethanol/water OCM, compared with no measurable release into SVF only. Increasing the concentration of Tween 80 in the SVF medium (1, 3 and 5% w/w) led to increased UC781 release (11, 16 and 18mg, respectively), demonstrating that vaginal fluid solubility of UC781 may be rate-determining in vivo. In the TCM, UC781 accumulates in the receptor cell medium over time, despite not being measured in the donor medium containing the ring device. Incorporation of Tween 80 directly into the ring provided enhanced release in both donor and receptor cells.

CONCLUSIONS: Release of UC781 was influenced by the choice of release medium and the inclusion of Tween 80 in the ring. Although use of SVF-only in the OCM indicated no measurable UC781 release from rings, data from the TCM confirms that UC781 is not only released but is also capable of penetrating across the model epithelial membrane. The TCM may therefore provide a more representative in vitro release model for mimicking in vivo absorption.

Influence of solution viscosity and injection protocol on distribution patterns of jet injectors: Application to photodynamic tumour targeting

Photodynamic therapy of deep or nodular skin tumours is currently limited by the poor tissue penetration of the porphyrin precursor 5-aminolevulinic acid (ALA) and preformed photosensitisers. In this study, we investigated the potential of jet injection to deliver both ALA and a preformed photosensitiser (meso-tetra (N-methyl-4-pyridyl) porphine tetra tosylate, TMP) into a defined volume of skin. Initial studies using a model hydrogel showed that as standoff distance is increased, injection depth decreases. As the ejected volume is increased, injection depth increases. It was also shown, for the first time, that, as injection solution viscosity was increased, for a given injection setting and standoff distance, both total depth of jet penetration, L-t, and depth at which the maximum width of the penetration pattern occurred, L-m, decreased progressively. For a standoff distance of zero, the maximum width of the penetration pattern, L-w, increased progressively with increasing viscosity at each of the injection settings. Conversely, when the standoff distance was 2.5 mm, L-w decreased progressively with increasing viscosity. Studies with neonate porcine skin revealed that an injection protocol comprising an 8.98 mPas solution, an arbitrary injection setting of 8 and a standoff distance of zero was capable of delivering photosensitisers to a volume of tissue (L-t of 2.91 mm, L-m of 2.14 mm, L-w of 5. 10 mm) comparable to that occupied by a typical nodular basal cell carcinoma. Both ALA and TMP were successfully delivered using jet injection, with peak tissue concentrations (67.3 mg cm(-3) and 5.6 mg cm(-3), respectively) achieved at a depth of around 1.0 mm and substantial reductions in drug concentration seen at depths below 3.0 mm. Consequently, jet injection may be suitable for selective targeting of ALA or preformed photosensitisers to skin tumours. (c) 2007 Elsevier B.V. All rights reserved.

A modified SILCS contraceptive diaphragm for long-term controlled release of the HIV microbicide dapivirine

Background: There is considerable interest in developing new multipurpose prevention technologies to address women's reproductive health needs. This study describes an innovative barrier contraceptive device--based on the SILCS diaphragm--that also provides long-term controlled release of the lead candidate anti-HIV microbicide dapivirine.

Study design: Diaphragm devices comprising various dapivirine-loaded polymer spring cores overmolded with a nonmedicated silicone elastomer sheath were fabricated by injection molding processes. In vitro release testing, thermal analysis and mechanical characterization were performed on the devices.

Results: A diaphragm device containing a polyoxymethylene spring core loaded with 10% w/w dapivirine provided continuous and controlled release of dapivirine over a 6-month period, with a mean in vitro daily release rate of 174 mcg/day. The mechanical properties of the new diaphragm were closely matched to the SILCS diaphragm.

Conclusions: The study demonstrates proof of concept for a dapivirine-releasing diaphragm with daily release quantities potentially capable of preventing HIV transmission. In discontinuous clinical use, release of dapivirine may be readily extended over 1 or more years. © 2013 Elsevier Inc. All rights reserved.

Micro-abrasion wear behaviour of TiAlCrSiN nanostructured coatings

The injection process of glass fibres reinforced plastics promotes the moulds surface degradation by erosion. In order to improve its wear resistance, several kinds of PVD thin hard coatings were used. It is well-known that nanostructures present a better compromise between hardness and toughness. Indeed, when the coating is constituted by a large number of ultra-thin different layers, cracks and interface troubles tend to decrease. However, it is not clear that these nanostructures present a better wear behaviour in erosion processes. In order to study its wear behaviour, a sputtered PVD nanostructured TiAlCrSiN coating was used. The substrate and film surfaces topography were analyzed by profilometry and atomic force microscopy techniques. Film adhesion to the substrate was evaluated by scratch tests. The surface hardness was measured with a Vickers micro-hardness tester. The wear resistance was evaluated by micro-abrasion with a rotating ball tribometer tests. Slurry of SiC particles in distilled water was used in order to provoke the surface abrasion. Different duration tests were performed in order to analyze the wear evolution. After these tests, the wear mechanisms developed were analyzed by scanning electron microscopy. Wear craters were measured and the wear rate was calculated and discussed. With the same purpose, coated inserts were mounted in an injection mould working with a 30% glass fibres reinforced polypropylene. After 45 000 cycles no relevant wear was registered.