Arterial luminal curvature and fibrous-cap thickness affect critical stress conditions within atherosclerotic plaque: An in vivo MRI-based 2D finite-element study

High mechanical stress in atherosclerotic plaques at vulnerable sites, called critical stress, contributes to plaque rupture. The site of minimum fibrous cap (FC) thickness (FCMIN) and plaque shoulder are well-documented vulnerable sites. The inherent weakness of the FC material at the thinnest point increases the stress, making it vulnerable, and it is the big curvature of the lumen contour over FC which may result in increased plaque stress. We aimed to assess critical stresses at FCMIN and the maximum lumen curvature over FC (LCMAX) and quantify the difference to see which vulnerable site had the highest critical stress and was, therefore, at highest risk of rupture. One hundred patients underwent high resolution carotid magnetic resonance (MR) imaging. We used 352 MR slices with delineated atherosclerotic components for the simulation study. Stresses at all the integral nodes along the lumen surface were calculated using the finite-element method. FCMIN and LCMAX were identified, and critical stresses at these sites were assessed and compared. Critical stress at FC MIN was significantly lower than that at LCMAX (median: 121.55 kPa; inter quartile range (IQR) = [60.70-180.32] kPa vs. 150.80 kPa; IQR = [91.39-235.75] kPa, p < 0.0001). If critical stress at FCMIN was only used, then the stress condition of 238 of 352 MR slices would be underestimated, while if the critical stress at LCMAX only was used, then 112 out of 352 would be underestimated. Stress analysis at FCMIN and LCMAX should be used for a refined mechanical risk assessment of atherosclerotic plaques, since material failure at either site may result in rupture.

How critical is fibrous cap thickness to carotid plaque stability? A flow-plaque interaction model

Background and Purpose Acute cerebral ischemic events are associated with rupture of vulnerable carotid atheroma and subsequent thrombosis. Factors such as luminal stenosis and fibrous cap thickness have been thought to be important risk factors for plaque rupture. We used a flow-structure interaction model to simulate the interaction between blood flow and atheromatous plaque to evaluate the effect of the degree of luminal stenosis and fibrous cap thickness on plaque vulnerability. Methods A coupled nonlinear time-dependent model with a flow-plaque interaction simulation was used to perform flow and stress/strain analysis in a stenotic carotid artery model. The stress distribution within the plaque and the flow conditions within the vessel were calculated for every case when varying the fibrous cap thickness from 0.1 to 2 mm and the degree of luminal stenosis from 10% to 95%. A rupture stress of 300 kPa was chosen to indicate a high risk of plaque rupture. A 1-sample t test was used to compare plaque stresses with the rupture stress. Results High stress concentrations were found in the plaques in arteries with >70% degree of stenosis. Plaque stresses in arteries with 30% to 70% stenosis increased exponentially as fibrous cap thickness decreased. A decrease of fibrous cap thickness from 0.4 to 0.2 mm resulted in an increase of plaque stress from 141 to 409 kPa in a 40% degree stenotic artery. Conclusions There is an increase in plaque stress in arteries with a thin fibrous cap. The presence of a moderate carotid stenosis (30% to 70%) with a thin fibrous cap indicates a high risk for plaque rupture. Patients in the future may be risk stratified by measuring both fibrous cap thickness and luminal stenosis.

Investigating physical properties of solid dosage forms during pharmaceutical processing : Process analytical applications of vibrational spectroscopy

In order to improve and continuously develop the quality of pharmaceutical products, the process analytical technology (PAT) framework has been adopted by the US Food and Drug Administration. One of the aims of PAT is to identify critical process parameters and their effect on the quality of the final product. Real time analysis of the process data enables better control of the processes to obtain a high quality product. The main purpose of this work was to monitor crucial pharmaceutical unit operations (from blending to coating) and to examine the effect of processing on solid-state transformations and physical properties. The tools used were near-infrared (NIR) and Raman spectroscopy combined with multivariate data analysis, as well as X-ray powder diffraction (XRPD) and terahertz pulsed imaging (TPI). To detect process-induced transformations in active pharmaceutical ingredients (APIs), samples were taken after blending, granulation, extrusion, spheronisation, and drying. These samples were monitored by XRPD, Raman, and NIR spectroscopy showing hydrate formation in the case of theophylline and nitrofurantoin. For erythromycin dihydrate formation of the isomorphic dehydrate was critical. Thus, the main focus was on the drying process. NIR spectroscopy was applied in-line during a fluid-bed drying process. Multivariate data analysis (principal component analysis) enabled detection of the dehydrate formation at temperatures above 45°C. Furthermore, a small-scale rotating plate device was tested to provide an insight into film coating. The process was monitored using NIR spectroscopy. A calibration model, using partial least squares regression, was set up and applied to data obtained by in-line NIR measurements of a coating drum process. The predicted coating thickness agreed with the measured coating thickness. For investigating the quality of film coatings TPI was used to create a 3-D image of a coated tablet. With this technique it was possible to determine coating layer thickness, distribution, reproducibility, and uniformity. In addition, it was possible to localise defects of either the coating or the tablet. It can be concluded from this work that the applied techniques increased the understanding of physico-chemical properties of drugs and drug products during and after processing. They additionally provided useful information to improve and verify the quality of pharmaceutical dosage forms

Die Großstadt als Gegner? : Zur Wahrnehmung Berlins in Literatur, Film und Hörspiel der späten Weimarer Republik

Tässä tutkielmassa tarkastellaan, miten Berliinin suurkaupunki vaikutti Weimarin tasavallan loppuaikoina yksilöön. Tutkimusaineistona on Alfred Döblinin romaani Berlin Alexanderplatz sekä Walter Ruttmannin elokuva Berlin. Die Sinfonie der Großstadt ja kuunnelma Weekend. Teoreettisena taustana hyödynnetään kulttuuri- ja mediahistorian mentaliteetti- ja sosiaalihistoriaa. Aihetta käsitellään myös historiallis-temaattisesta lähtökohdasta, eli työssä tutkitaan todellisen Berliinin asemaa kyseisenä aikana, modernin metropolin olemusta, modernin ajan murrosvaihetta sekä uusasiallisen taidesuuntauksen vaikutusta teoksiin. Weimarin tasavallan aikana Saksassa elettiin murroksen keskellä. Toisaalta yhteiskunta oli poliittisesti pirstoutunut ja taloudellisesti epävakaa, mutta toisaalta kulttuurielämä oli lyhyen aikaa rikasta. Suurkaupungin asukkailla oli enemmän vapaa-aikaa ja mahdollisuuksia toteuttaa itseään omassa ympäristössään. Toisaalta ajan ristiriitaisuus kuitenkin vaikeutti yksilöllisen elämäntavan toteutumista; ihmiset odottivat murroskauden päättymiseltä materiaalista tyydytystä, jolloin henkiselle kehitykselle jäi vähän tilaa. Tärkein kysymyksenasettelu koskee suurkaupungin roolia oman aikansa tuotteena: missä määrin kaupunki oli ihmisen todellinen vastustaja ja missä määrin sen asema oli kuviteltua? Todellisen Berliinin suhdetta reflektoidaan fiktiiviseen suurkaupunkiympäristöön. Ensin tarkastellaan Berliiniä toimijana murroskaudella ja sitten käsitellään ajan ja tilan havainnointia. Koska teokset ovat fiktiivisiä, erityisen tarkastelun kohteena on todellisuuden, fiktion ja simulaation suhde. Tässä yhteydessä tarkastellaan myös kaupungin ja maaseudun välistä problematiikkaa. Kolmannessa osassa esille nousee yksilön ja massan välinen suhde, joka sekin vaikuttaa ihmisen ja suurkaupungin väliseen vastakkainasetteluun. Ilmensikö koneiden ja liikenteen dominoiva asema futuristista asetelmaa? Lisäksi käsitellään alamaailman ja kultaisen 20-luvun välistä kuilua. Kaikkia kolmea teosta yhdistää 24 tunnin aikakäsite; ajalla on selkeästi rajattu alku ja loppu, ja myös tilan käsite on tarkastelussa tärkeä. Kaikissa teoksissa on hyödynnetty montaasitekniikkaa. Kohtaukset vaihtuvat hyvinkin nopeasti, jolloin lukija, katsoja tai kuulija vieraantuu varsinaisesta kohteestaan. Montaasi vaikuttaa ratkaisevasti myös kaupungin ja yksilön suhteen kuvaukseen. Suurkaupungista muotoutuu lähes hirviömäinen, personifioitu subjekti, joka konemaisella olemuksellaan pyrkii nujertamaan pienen ihmisen. Döblinin romaanissa kertoja toimii ikään kuin yksilöä vastaan liittämällä kerronnan väliin uutisaiheita, säätiedotuksia ja kohtalokertomuksia. Elokuvassa ja kuunnelmassa teknologisen kehityksen ihannointi on noussut etualalle: ihmiset muistuttavat sekä yksilöinä että massana koneita, jotka liikkuvat hektisen mekaanisesti eteenpäin kuin liikennevälineet. He eivät kyseenalaista ympäristöään eivätkä koe olevansa oravanpyörässä. Romaanin päähenkilö on heijastanut omat pelkonsa konkreettisesti suurkaupungin infrastruktuuriin, kerrostaloihin, jotka tuntuvat kaatuvan hänen päälleen. Yksilöllinen kehitys on vaarassa pysähtyä, sillä koneistuminen tekee yksilöistä massaa. Elokuvassa ja kuunnelmassa kamppailu suurkaupunkiorganismin ja ihmisten välillä jatkuu, mutta romaanissa kamppailu päättyy päähenkilön parantumiseen. Hänestä tulee mallikansalainen - vaiennettu ja kuuliainen. Kaikkien kolmen teoksen hahmoja kuvataan modernin ajan uhreina. Heiltä puuttuu mekanismi, jolla he voisivat käsitellä kokonaisuuksia. Modernin ajan hahmojen elämä on lopulta kuin tanssia tulivuoren päällä - epävarmaa ja riskialtista.

Depth profile composition studies of thin film CdS: Cu,S solar cells using XPS and AES

Surface composition and depth profile studies of hemiplated thin film CdS:CuzS solar cells have been carried out using x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) techniques. These studies indicate that the junction is fairly diffused in the as-prepared cell. However, heat treatment of the cell at 210°C in air relatively sharpens the junction and improves the cell performance. Using the Cu(2p3p)/S(2p) ratio as well as the Cu(LVV)/(LMM) Auger intensity ratio, it can be inferred that the nominal valency of copper in the layers above the junction is Cut and it is essentially in the CUSS form. Copper signals are observed from layers deep down in the cell. These seem to appear mostly from the grain boundary region. From the observed concentration of Cd, Cu and S in these deeper layers and the Cu(LVV)/(LMM) ratio it appears that the signals from copper essentially originate partly from copper in CuS and partly from Cu2t trapped in the lattice. It is significant to note that the nominal valence state of copper changes rather abruptly from Cut to Cuz+ across the junction.

When film, fashion & interiors collide: Designing the After Darkly Graduate Fashion Show

In 2013 QUT Interior Design and Fashion Disciplines partnered to design the Catwalk for the QUT After Darkly Graduate Fashion Show. The ephemeral work (catwalk canopy and cinematic affects) was developed through collaboration between the authors based upon an undergraduate interior design unit ‘Filmic Interiors’ in which students were tasked with designing a fashion show. Filmic Interiors exploited the potential of film to influence, understand, and develop novel interior spaces through consideration of mise-en-scene, cinematic effects and atmospheric design strategies engaged by key film directors Jean Pierre Jeunet and Darren Aronofsky. The design outcome represents a hybridisation of student design proposals, contemplating both film and emerging collections from graduate fashion students. The work explored a number of iterations each testing material qualities and immaterial cinematic affects, as a means to develop new space. The process was led by experimentation undertaken by the designers through previous studio explorations surrounding the theme of ‘Strange Space’ and design practice ‘Making Strange’(Lindquist & Pytel, 2012). In doing so, the work paralleled the material formations of ‘obsessive collections’ and ‘making do’ evident in Jeunet’s scenography, rendering uncanny hybrid space (Ezra, 2008). Evocation of the immaterial found in much of director Aronofsky’s work, also became critical in the atmospheric experience intended for the show. This paper explores the process of collaboration and material experimentation in design, approached through a filmic lens. It provides insight into what happens when one enters into what can be termed an ‘ecology of production’, whereby the experimental making becomes the collaborative agent between designers, disciplines, and between stage and spectators. Finally it underlines the importance of ‘finding the work’ through material making and testing rather than through more controlled formalistic responses.

Morphological transitions in polymer monolayers under compression

We present a systematic investigation of morphological transitions in poly vinylacetate Langmuir monolayers. On compression, the polymer monolayer is converted to a continuous membrane with a thickness of similar to 2-3 nm. Above a certain surface concentration the monolayer, on water, undergoes a morphological transition-buckling, leading to formation of striped patterns of period of lambda(b)similar to 160 nm, as determined from in situ grazing incidence small angle x-ray scattering measurements. The obtained value is much smaller than what has been typically observed for Langmuir monolayers on water or thin films on soft substrates. Using existing theories for buckling of fluidlike films on fluid substrates, we obtain very low values of bending rigidity and Young's modulus of the polymer monolayer compared to that observed earlier for lipid or polymeric monolayers. Since buckling in these monolayers occurs only above a certain surface concentration, we have looked at the possibility that the buckling in these films occurs due to changes in their mechanical properties under compression. Using the model of Huang and Suo of buckling of solidlike films on viscoelastic substrates, we find values of the mechanical properties, which are much closer to the bulk values but still significantly lower. Although the reduction could be along the lines of what has been observed earlier for ultrathin polymer film or surface layers of polymers, the possibility of micromechanical effects also determining the buckling in such polymer monolayers cannot be ruled out. We have provided possible explanation of the buckling of the poly vinylacetate monolayers in terms of the change in isothermal compression modulus with surface concentration.

Trimming studies on polymer thick-film resistors

PVC-graphite polymer thick-film resistors were trimmed by a conventional air abrasive technique and the post-trim drift in resistance with time was found to be negative. The net decrease in resistance of trimmed resistors in a given time was found to be a function of resistor composition, cutting speed and temperature. Detailed studies showed this decrease to be due to a decrease in cut width with time. Two new methods, namely bombardment trimming and radiation trimming, were also tried for adjusting the resistance of these resistors and the results were compared with those obtained from abrasive trimming studies.

China, film coproduction and soft power competition

This thesis investigates China's film internationalism and coproduction strategy based on three cases: Hong Kong and China film coproduction; US and China without any state-level agreements; Australia and China based on an official coproduction treaty. It investigates the evolution of coproduction in the film industry, the process of coproduction, foreign film companies' strategies of adjustment to state policies, and the culture and complexities that hinder coproduction. It surveys the current environment for China film coproduction and investigates the degree to which film coproduction has been - to this stage - a contributor to China's global cultural presence – its soft power.

Film cooling at hypersonic Mach numbers using forward facing array of micro-jets

Experimental investigations are carried out in the IISc hypersonic shock tunnel on film cooling effectiveness of a single jet (diameter 2 mm and 0.9 mm), and an array forward facing of micro-jets (diameter 300 mu m each) of same effective area (corresponding to the respective single jet). The single jet and the corresponding micro-jets are injected from the stagnation zone of a blunt cone model (58, apex angle and nose radius of 35 mm). Nitrogen and Helium are injected as coolant gases. Experiments are performed at freestream Mach number 5.9, at 0 degrees angle of attack, with a stagnation enthalpy of 1.84 MJ/kg, with and without injections. The ratios of the jet stagnation pressure to the freestream pitot pressure used in the present study are 1.2 and 1.45. Up to 50% reduction in surface heat transfer rate was observed with the array of micro-jets, compared to that of the respective single jet with nitrogen as the coolant, while the corresponding eduction was up to 37% for helium injection, with the schlieren flow visualizations showing no major change in the shock standoff distance, and thus no major changes in other aerodynamic aspects such as drag.

Coalescence of drops in stirred dispersion. A white noise model for coalescence

Coalescence between two droplets in a turbulent liquid-liquid dispersion is generally viewed as a consequence of forces exerted on the drop-pair squeezing out the intervening continuous phase to a critical thickness. A new synthesis is proposed herein which models the film drainage as a stochastic process driven by a suitably idealized random process for the fluctuating force. While the true test of the model lies in detailed parameter estimations with measurement of drop-size distributions in coalescing dispersions, experimental measurements on average coalescence frequencies lend preliminary support to the model.