Contact Line Instability of Gravity-Driven Flow of Power-Law Fluids

The moving contact line of a thin fluid film can often corrugate into fingers, which is also known as a fingering instability. Although the fingering instability of Newtonian fluids has been studied extensively, there are few studies published on contact line fingering instability of non-Newtonian fluids. In particular, it is still unknown how shear-thinning rheological properties can affect the formation, growth, and shape of a contact line instability. Our previous study (Hu and Kieweg, 2012) showed a decreased capillary ridge formation for more shear-thinning fluids in a 2D model (i.e. 1D thin film spreading within the scope of lubrication theory). Those results motivated this study's hypothesis: more shear-thinning fluids should have suppressed finger growth and longer finger wavelength, and this should be evident in linear stability analysis (LSA) and 3D (i.e. 2D spreading) numerical simulations. In this study, we developed a LSA model for the gravity-driven flow of shear-thinning films, and carried out a parametric study to investigate the impact of shear-thinning on the growth rate of the emerging fingering pattern. A fully 3D model was also developed to compare and verify the LSA results using single perturbations, and to explore the result of multiple-mode, randomly imposed perturbations. Both the LSA and 3D numerical results confirmed that the contact line fingers grow faster for Newtonian fluids than the shear-thinning fluids on both vertical and inclined planes. In addition, both the LSA and 3D model indicated that the Newtonian fluids form fingers with shorter wavelengths than the shear-thinning fluids when the plane is inclined; no difference in the most unstable (i.e. emerging) wavelength was observed at vertical. This study also showed that the distance between emerging fingers was smaller on a vertical plane than on a less-inclined plane for shear-thinning fluids, as previously shown for Newtonian fluids. For the first time for shear-thinning fluids, these results connect trends in capillary ridge and contact line finger formation in 2D models, LSA, and 3D simulations. The results can provide us insights on how to optimize non-Newtonian fluid properties to minimize a fingering instability in many industrial and biological applications

Gravity-Driven Thin Film Flow of an Ellis Fluid

The thin film lubrication approximation has been studied extensively for moving contact lines of Newtonian fluids. However, many industrial and biological applications of the thin film equation involve shear-thinning fluids, which often also exhibit a Newtonian plateau at low shear. This study presents new numerical simulations of the three-dimensional (i.e. two-dimensional spreading), constant-volume, gravity-driven, free surface flow of an Ellis fluid. The numerical solution was validated with a new similarity solution, compared to previous experiments, and then used in a parametric study. The parametric study centered around rheological data for an example biological application of thin film flow: topical drug delivery of anti-HIV microbicide formulations, e.g. hydroxyethylcellulose (HEC) polymer solutions. The parametric study evaluated how spreading length and front velocity saturation depend on Ellis parameters. A lower concentration polymer solution with smaller zero shear viscosity (η0), τ1/2, and λ values spread further. However, when comparing any two fluids with any possible combinations of Ellis parameters, the impact of changing one parameter on spreading length depends on the direction and magnitude of changes in the other two parameters. In addition, the isolated effect of the shear-thinning parameter, λ, on the front velocity saturation depended on τ1/2. This study highlighted the relative effects of the individual Ellis parameters, and showed that the shear rates in this flow were in both the shear-thinning and plateau regions of rheological behavior, emphasizing the importance of characterizing the full range of shear-rates in rheological measurements. The validated numerical model and parametric study provides a useful tool for future steps to optimize flow of a fluid with rheological behavior well-described by the Ellis constitutive model, in a range of industrial and biological applications

The Beginning Spanish Lexicon: A Web-based interface to calculate phonological similarity among Spanish words in adults learning Spanish as a foreign language

A number of resources provide psycholinguistic researchers with information about the words that the typical child or adult knows in a variety of languages. What is currently not available is a resource that provides information about the words that a typical adult learning a foreign language knows. We created such a resource for Spanish: The Beginning Spanish Lexicon. The present report describes the words contained in this web-accessible resource, and the information about those words provided by the interface. This information is freely accessible at: http://www.people.ku.edu/~mvitevit/BegSpanLex.htm

Langzeitverläufe nach Operationen aufgrund eines Rhinophyms bzw. einer Akne inversa - dargestellt anhand des Patientengutes der Universitäts-Hautklinik Regensburg aus den Jahren 2004 bis 2013

In vorliegender Arbeit wurden Langzeitverläufe nach operativer Behandlung eines Rhinophyms bzw. einer Akne inversa untersucht. Als zentraler Bestandteil erfolgte jeweils eine Patientenbefragung mittels eines speziell zu Studienzwecken konzipierten Fragebogens. Im Hinblick auf die operative Behandlung des Rhinophyms erwies sich eine Abtragung der knollenförmigen Talgdrüsenhyperplasien im Bereich der Nase in Form eines Dermashavings mit nachfolgender Sekundärheilung als schmerz- und komplikationsarmes Verfahren. Gleichzeitig war eine verhältnismäßig geringe Rezidivquote von unter 20 % zu verzeichnen. Im postoperativen Verlauf zeigten sich eine langfristige Ergebnisstabilität sowie hohe Patientenzufriedenheit. Hinsichtlich des operativen Vorgehens bei Akne inversa lag nach ausgedehnter Exzision erkrankten Gewebes und nachfolgender Sekundärheilung eine gut tolerable Schmerzintensität bei allerdings beachtlicher Rate an - wenn auch selten schweren - Komplikationen vor. Trotz einer verhältnismäßig hohen Rezidivquote von 40,5 % konnte dennoch in 60 % über einen Zeitraum von > 1 Jahr ein stabiles Operationsergebnis aufrechterhalten werden. Das operative Outcome wurde durchwegs positiv bewertet und mehr als jeder zweite Studienteilnehmer äußerte seine Bereitschaft, sich im Rezidivfall einem erneuten Eingriff in unserer Abteilung zu unterziehen

Analysis and characterisation of five novel Barentsz interactors in the context of nonsense-mediated mRNA decay

Nonsense-mediated mRNA decay“ (NMD) ist ein Mechanismus zur Regulierung der Genexpression auf post-transkriptioneller Ebene in Eukaryonten durch die Beseitigung fehlerhafter RNAs mit einem verfrühten Stop-Codon, auch „Premature termination codon (PTC)“ genannt. Andernfalls würden diese RNAs zur Bildung verkürzter Proteine mit möglicherweise für die Zelle gefährlichen Funktionen führen, wie es bei Krankheiten, wie z. B. Krebs, oft der Fall ist. In dieser Diplomarbeit wurden fünf potentielle NMD-Komponenten und Barentsz-Interaktoren (NPM1, DDX5, U5-116 kDa, RBMX und RBM4) näher auf ihre Rolle in NMD untersucht. Zu diesem Zweck wurde ein funktioneller NMD-Assay etabliert. Gegen diese Proteine gerichtete „Short hairpin RNA (shRNA)“-Plasmide wurden hergestellt und getestet. Danach wurden die Expressionslevels der entsprechenden Proteine mittels ihrer shRNA-Plasmide vermindert und überprüfte, ob dies zur Akkumulierung von PTC-enthaltenden NMD-Reporter-Konstrukten führt, wie im Fall des Barentsz-Knockdowns. Hierfür wurden die Expressionslevels und somit der Abbau von eigens eingebrachten T-Zellrezeptor-ß (TCR-ß) - und ß-Globin-NMD-Reporter-Konstrukten mit und ohne PTC über semiquantitative und Real-time-PCR verglichen. Zusätzlich wurde eine Neomycin/G418-Selektion durchgeführt, um erfolgreich transfizierte Zellen anzureichern. Für NPM1, RBMX und RBM4 konnten schließlich noch keine Aussagen getroffen werden. Hingegen wurden die Btz-Interaktoren DDX5 und U5-116 kDa als zwei neue NMD-Komponenten identifiziert.Nonsense-mediated mRNA decay (NMD) is a mechanism to post-transcriptionally regulate gene expression in eukaryotes via degradation of aberrant RNAs with a so-called premature termination codon (PTC). Otherwise, these RNAs would give rise to truncated proteins with potentially deleterious functions which is often the case in diseases like cancer. In this diploma thesis, five potential NMD components and novel Barentsz interactors (NPM1, DDX5, U5-116 kDa, RBMX and RBM4) were investigated for their role in NMD. Therefore, an NMD Assay was established. Short hairpin RNA (shRNA) plasmids targeting the candidates were generated and tested. Subsequently, it was investigated whether the depletion of the respective candidate proteins using shRNAs caused accumulation of PTC-containing NMD reporter constructs, as it is the case in the Barentsz knockdown. Upon depletion, the expression levels and the decay of exogenously provided T-cell receptor ß (TCR-ß) and ß-Globin NMD reporter constructs with and without PTC were compared and measured using semiquantitative PCR and real-time PCR. In addition, neomycin/G418 selection was performed to enrich for successfully transfected, candidate-depleted cells. Finally, no firm conclusion was possible regarding NPM1, RBMX and RBM4. The Btz interactors DDX5 and U5-116 kDa, however, were identified as two novel NMD components

OroSTIFF: Face-referenced measurement of perioral stiffness in health and disease

A new device and automated measurement technology known as OroSTIFF is described to characterize non-participatory perioral stiffness in healthy adults for eventual application to patients with orofacial movement disorders associated with neuromotor disease, traumatic injury, or congenital clefts of the upper lip. Previous studies of perioral biomechanics required head stabilization for extended periods of time during measurement which precluded sampling patients with involuntary body/head movements (dyskinesias), or pediatric subjects. The OroSTIFF device is face-referenced and avoids the complications associated with head-restraint. Supporting data of non-participatory perioral tissue stiffness using OroSTIFF are included from 10 male and 10 female healthy subjects. The OroSTIFF device incorporates a pneumatic glass air cylinder actuator instrumented for pressure, and an integrated subminiature displacement sensor to encode lip aperture. Perioral electromyograms were simultaneously sampled to confirm passive muscle state for the superior and inferior divisions of the orbicularis oris muscles. Perioral stiffness, derived as a quotient from resultant force (ΔF) and interangle span (ΔX), was modeled with multilevel regression techniques. Real-time calculation of the perioral stiffness function demonstrated a significant quadratic relation between imposed interangle stretch and resultant force. This stiffness growth function also differed significantly between males and females. This study demonstrates the OroSTIFF ‘proof-of-concept’ for cost-effective non-invasive stimulus generation and derivation of perioral stiffness in a group of healthy unrestrained adults, and a case study to illustrate the dosedependent effects of Levodopa on perioral stiffness in an individual with advanced Parkinson’s disease who exhibited marked dyskinesia and rigidity

Tensile strength of a surgeon’s or a square knot

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Objective—To test the integrity of surgeon’s knots and flat square knots using four different suture materials. Study Design—Chromic catgut, polyglactin 910, silk, and polydioxanone sutures were tied in the two types of knot configurations. For all sutures, a 0-gauge United States Pharmacopeia suture was used. Knots were tied by a single investigator (JB). Suture was soaked in 0.9 % sodium chloride for 60 seconds and subsequently transferred to a tensiometer where the tails were cut to 3 mm length. We compared the knots, measuring knot strength using a tensiometer until the sutures broke or untied. Results—A total of 119 knots were tied. We found no difference in mean tension at failure between a surgeon’s knot (79.7 Newtons) and a flat square knot (82.9 Newtons). Using a Chisquare test, we did not find a statistically significant difference in the likelihood of knots coming untied between surgeon’s knots (29%) and flat square knots (38%). Conclusions—Under laboratory conditions, surgeon’s knots and flat square knots did not differ in tension at failure or likelihood of untying

Veränderungen im Informationsverhalten in der Corona-Krise und ihre Auswirkungen auf die Sichtweisen junger Menschen

Die COVID-19-Pandemie hat das Leben von Menschen auf der ganzen Welt von Grund auf verändert. Gleichzeitig trägt das Verhalten der Menschen zur Überwindung der Pandemie bei, sei es in Form der Einhaltung der Pandemieregelungen, sei es durch die Bereitschaft, sich gegen COVID-19 impfen zu lassen. Derzeit zeigt sich jedoch in Ländern wie Deutschland, die über ausreichend Impfstoff verfügen, eine gewisse Impfmüdigkeit. Da Studien bereits gezeigt haben, dass zwischen Informationsverhalten und Impfbereitschaft ein Zusammenhang besteht, untersucht diese Arbeit anhand einer Längsschnittsstudie Veränderungen des Informationsverhaltens junger Menschen unter 35 Jahren im Verlauf der Pandemie im Jahr 2020. Besonderes Augenmerk wird dabei auf die Konsequenzen des Informationsverhaltens für die Zuversicht und die Impfbereitschaft in dieser Zielgruppe gelegt. Dabei zeigt sich durchaus eine Pandemiemüdigkeit unter den Befragten, die sich darin äußert, dass die Befragten am Ende des Jahres 2020 weniger Zeit damit verbringen, sich über das Virus oder die Pandemie zu informieren als noch 7 Monate zuvor. Die Daten offenbaren auch Zusammenhänge zwischen dem Informationsverhalten, dem Grad der Informiertheit und der Zuversicht, dass die Pandemie überwunden wird. Schließlich sind Personen, die sich besser informiert fühlen, eher bereit, eine Impfung zu akzeptieren, womit eine faktenbasierte, glaubhafte Information der Bevölkerung offenbar ein entscheidender Faktor der Pandemiebekämpfung ist

Tracking Talking: Dual Task Costs of Planning and Producing Speech for Young versus Older Adults

A digital pursuit rotor was used to monitor speech planning and production costs by time-locking tracking performance to the auditory wave form produced as young and older adults were describing someone they admire. The speech sample and time-locked tracking record were segmented at utterance boundaries and multilevel modeling was used to determine how utterance-level predictors such as utterance duration or sentence grammatical complexity and person-level predictors such as speaker age or working memory capacity predicted tracking performance. Three models evaluated the costs of speech planning, the costs of speech production, and the costs of speech output monitoring. The results suggest that planning and producing propositionally dense utterances is more costly for older adults and that older adults experience increased costs as a result of having produced a long, informative, or rapid utterance

Synthesis and evaluation of novel dental monomer with branched aromatic carboxylic acid group

A new glycerol-based dimethacrylate monomer with an aromatic carboxylic acid, 2-((1,3-bis(methacryloyloxy)propan-2-yloxy)carbonyl)benzoic acid (BMPB), was synthesized, characterized, and proposed as a possible dental co-monomer for dentin adhesives. Dentin adhesives containing 2-hydroxyethyl methacrylate (HEMA) and 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]propane (BisGMA) in addition to BMPB were formulated with water at 0, 5, 10, and 15 wt % to simulate wet, oral conditions, and photo-polymerized. Adhesives were characterized with regard to viscosity, real-time photopolymerization behavior, dynamic mechanical analysis, and microscale 3D internal morphologies and compared with HEMA/BisGMA controls. When formulated under wet conditions, the experimental adhesives showed lower viscosities (0.04–0.07 Pa s) as compared to the control (0.09–0.12 Pa s). The experimental adhesives showed higher glass transition temperature (146–157°C), degree of conversion (78–89%), and rubbery moduli (33–36 MPa), and improved water miscibility (no voids) as compared to the controls (123–135°C, 67–71%, 15–26 MPa, and voids, respectively). The enhanced properties of these adhesives suggest that BMPB with simple, straight-forward synthesis is a promising photocurable co-monomer for dental restorative materials