Abstract Multiphase Droplet Interactions with a Single Fiber By: Noor M. Farhan A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University. Virginia Commonwealth University, 2019 Director: Hooman V. Tafreshi, Professor, Department of Mechanical and Nuclear Engineering Formulating the physics of droplet adhesion to a fiber is interesting intellectually and important industrially. A typical example of a droplet–fiber system in nature is the dew droplets on spider webs, where droplets first precipitate and grow on the fibers, but they eventually fall when they become too heavy. Obviously, quantifying the force of adhesion between a droplet and a fiber is crucial in designing fog harvesting devices or manufacturing filtration media for liquid–gas or liquid–liquid separation, among many other industrial applications. This study is aimed at developing a mathematical framework for the mechanical forces between a droplet and a fiber in terms of their physical and wetting properties. To this end, a series of experiments were conducted to detach ferrofluid droplets of varying volumes from fibers with different diameters and Young–Laplace contact angles (YLCAs) in a controlled magnetic field. The force of detachment was measured using a sensitive scale and used along with the results of numerical simulations to develop a semi-analytical expression for the force required to detach a droplet from a fiber. This universally-applicable expression allows one to predict the force detachment without the need to run an experiment or a computer simulation. This work also reports on the use of magnetic force to measure the force of detachment for nonmagnetic droplets for the first time. This is accomplished by adding a small amount of a ferrofluid to the original nonmagnetic droplet to create a compound droplet with the ferrofluid nesting inside or cloaking the nonmagnetic droplet. The ferrofluid is then used to induce a body force to the resulting compound droplet and thereby detach it from the fiber. The recorded detachment force is used directly (the case of nesting ferrofluid) or after scaling (the case of cloaking ferrofluid) to obtain the force of detachment for the original nonmagnetic droplet. The accuracy of these measurements was examined through comparison with numerical simulations as well as available experimental data in the literature. In addition, a simple method is developed to directly measure the intrinsic contact angle of a fiber (i.e., Young–Laplace Contact angle of the fiber material) with any arbitrary liquid. It is shown that the intrinsic contact angle of a fiber can be obtained by simply measuring the angle between the tangent to the fiber surface and the tangent to the droplet at the contact line, if the droplet possesses a clamshell conformation and is viewed from the longitudinal direction. The novelty of the proposed method is that its predictions are not affected by the volume of the droplet used for the experiment, the wettability of the fiber, the surface tension of the liquid, or the magnitude of the body force acting on the droplet during the experiment. Also, a liquid droplet interaction with granular coatings is simulated and the droplet apparent contact angle (ACA) and the transition from Cassie (fully dry) to Wenzel (fully wet) state as a function to the roughness wavelength have been studied. For a fixed droplet volume, two different granular coatings have been used, spherical and hemispherical bumps. It is demonstrated that the chemistry (YLCA) and geometrical parameters for the granular microtexture play an important effect on the droplet ACA and its transition from Cassie to Wenzel state.

Den teknologiska utvecklingen har bidragit till att arbete kan utföras under mer flexiblaformer. Syftet med studien var därför att undersöka om skillnader i upplevelsen avinformations och kommunikationsteknikens krav (IKT-krav) påverkade möjligheterna att dragränser mellan arbete och fritid. Metoden för datainsamling var kvantitativ och 31enhetschefer erbjöds möjlighet att delta i studien genom att besvara en webbenkät.Svarsfrekvensen uppgick till 58 % (N = 18). Studiens huvudresultat visade på signifikantaskillnader i förhållande till mental distansering från arbetet, där de som upplevde låga IKTkravskattade förmågan till mental distansering högre och de som upplevde höga IKT-kravskattade förmågan till mental distansering lägre. Det betyder att när kraven om tillgänglighetoch förväntningar på respons ökar på enhetscheferna, så är upplevelsen att förmågan tillmental distansering minskar. Utövad gränsstrategi visade inte på några signifikantaskillnader. Resultaten betraktas med försiktighet eftersom deltagarantalet är lågt. Någragenerella slutsatser bör inte dras men den praktiska relevansen är av värde i sammanhanget. / Technology development has contributed work to be performed under more flexible forms.The aim of the study was to investigate if information and communication technologydemands (ICT-demands) affected the ability to create boundaries between work and leisure.The method of collecting data was quantitative and 31 managers for different units in thehealth and care sector had the opportunity to participate by answer an websurvey. 58 %responded and the main result showed significant differences in order to psychologicaldetachment. Those who experienced low ICT-demands estimated higher ability topsychological detachment from work, and those who experienced high ICT-demandsestimated the ability to psychological detachment lower. This means that when demands likeavailability and response expectations increases among the managers, the sense of beingaway from work decreases. Boundary management on the other hand, does not show anysignificant differences in experience. The results are considered with caution as the numberof participants are low. Some general conclusions should not be drawn but the practicalrelevance is of value in the context.

<p><span lang="EN-GB" style="font-size:12.0pt / font-family:&quot / Times New Roman&quot / ,&quot / serif&quot / mso-fareast-font-family:&quot / Times New Roman&quot / mso-ansi-language:EN-GB / mso-fareast-language: EN-ZA">Literature shows that cataracts are the leading cause of blindness globally and nationally. Retinal detachment has also been a substantial problem both globally and nationally. Both of these conditions are prevalent in patients of 50 years and older. The treatment for both conditions is for surgery to be performed. In the Western Cape the three leading hospitals do not have ophthalmic pre-operative and post-operative protocols<span style="mso-bidi-font-weight:bold">.</span>Review question:What are the best practices to manage pre-operative and post-operative nursing care in patients waiting for cataract and retinal detachment surgery? bjectives:1. To determine the best practice in pre-operative and post-operative care in patients who have undergone cataract and/or retinal detachment surgery regarding: health education offered by nurses, counselling to prevent psychological effects, and positioning to prevent physical complications. 2. To develop a framework based on systematic reviews for pre-operative and post-operative ophthalmic nursing care in South Africa. Methodology: </span><span lang="EN-GB" style="font-size: 12.0pt / font-family:&quot / Times New Roman&quot / ,&quot / serif&quot / mso-ansi-language:EN-GB">A systematic review using the guide by the Centre for Reviews and Dissemination was done, and <span style="mso-bidi-font-weight:bold">studies were </span>identified by searching various electronic databases and visually scanning reference lists from the relevant studies. Studies that were included were evidence-based. All study types were considered and the studies were selected based on the title and, where available, the abstract. These were then assessed against the inclusion criteria. A narrative synthesis was used. Finally the evidence was summarised and a framework was drawn up, focusing on pre-operative and post-operative nursing care for cataract and retinal detachment surgery</span></p> <p>&nbsp / </p>

Children of alcoholics (COAs) are those who grow up in a home where one or more parent is an alcoholic; once adulthood is achieved, they are referred to as adult children of alcoholics (ACOAs). Several risk factors have been identified as a potential result from exposure to an alcoholic environment; however there is a dearth of literature exploring resilience in this population. Descriptive Narrative Inquiry was used to explore the question, Describe the qualities, processes, or internal motivational factors which have facilitated resilience for adult children of alcoholic parents. Two ninety-minute life history interviews were conducted with four participants, including the researcher. The participants were female, middle class, university students who considered themselves to be adult children of alcoholics who are resilient. A composite narrative was used to depict the results of this study, combining the data from each participants life story. The narrative was written in the first-person through the character of Sophie, and the data included is the result of a narrative analysis from the transcripts of the participants data. The narrative depicts the developmental stages of the participants lives, including childhood, adolescence, adulthood, and the present. Their experiences of growing up in an alcoholic home were documented at each stage. A thematic analysis was conducted, extracting the common themes, meaning made, and personal characteristics that were generated within and across participants that contributed to their development of resilience. The results are discussed in four major themes: Being in Relation: Others Create a Difference; Belief Systems: Spirituality, Religion, and Values; The Self: An Evolving Being; and Alcoholism: Meaning in Itself. It is through the dialogue of the participants experiences of resilience that awareness creates opportunity for advocacy for children and adult children of alcoholics. The implications of this research in relation to the experiences of resilience are discussed for children and adult children of alcoholics, educators, and counsellors. Directions for future research are addressed.

Plasma flow physics in magnetic nozzles must be clearly understood for optimal design of plasma propulsion devices. Toward that end, in this thesis we: i) perform an extensive literature survey of magnetic nozzle physics, ii) assess the validity of magnetohydrodynamics for studying magnetic nozzle physics, and iii) illustrate the effects of the Hall term in simple flows as well as in magnetic nozzle configurations through numerical experiments with the Magneto-Gas Kinetic Method (MGKM). The crucial steps necessary for thrust generation in magnetic nozzles are energy conversion, plasma detachment, and momentum transfer. These three physical phenomena must be understood to optimize magnetic nozzle design. The operating dimensionless parameter ranges of six prominent experiments are considered and the corresponding mechanisms are discussed. An order of magnitude analysis of the governing equations reveal: i) most magnetic nozzles under consideration operate at the edge of the continuum regime rendering continuum-based description and computation valid; ii) in the context of MHD framework, the generalized Ohm’s law must be used to capture all of the relevant physics. This work also continues the development of the Magneto Gas Kinetic Method (MGKM) computational tool. Validation of the solver is performed in shock-tube and Hartmann channel flows in the Hall physics regime. Comparison with theory and available data is made whenever possible. Novel numerical experiments of magnetic nozzle plasma jets in the Hall regime are performed, confirming the theoretically predicted azimuthal rotation of the plasma jet due to Hall physics. The primary conclusion from this work is that the addition of the Hall effect generates helical structures in magnetic nozzle plasma flows. Preliminary results are encouraging for future magnetic nozzle studies and further challenges are identified.

No description available.

Children of alcoholics (COAs) are those who grow up in a home where one or more parent is an alcoholic; once adulthood is achieved, they are referred to as adult children of alcoholics (ACOAs). Several risk factors have been identified as a potential result from exposure to an alcoholic environment; however there is a dearth of literature exploring resilience in this population. Descriptive Narrative Inquiry was used to explore the question, Describe the qualities, processes, or internal motivational factors which have facilitated resilience for adult children of alcoholic parents. Two ninety-minute life history interviews were conducted with four participants, including the researcher. The participants were female, middle class, university students who considered themselves to be adult children of alcoholics who are resilient. A composite narrative was used to depict the results of this study, combining the data from each participants life story. The narrative was written in the first-person through the character of Sophie, and the data included is the result of a narrative analysis from the transcripts of the participants data. The narrative depicts the developmental stages of the participants lives, including childhood, adolescence, adulthood, and the present. Their experiences of growing up in an alcoholic home were documented at each stage. A thematic analysis was conducted, extracting the common themes, meaning made, and personal characteristics that were generated within and across participants that contributed to their development of resilience. The results are discussed in four major themes: Being in Relation: Others Create a Difference; Belief Systems: Spirituality, Religion, and Values; The Self: An Evolving Being; and Alcoholism: Meaning in Itself. It is through the dialogue of the participants experiences of resilience that awareness creates opportunity for advocacy for children and adult children of alcoholics. The implications of this research in relation to the experiences of resilience are discussed for children and adult children of alcoholics, educators, and counsellors. Directions for future research are addressed.

published_or_final_version / Anatomy / Master / Master of Philosophy

Αντικείμενο της διδακτορικής διατριβής ήταν η διερεύνηση των μηχανισμών προσρόφησης των πρωτεϊνών και η μέτρηση των δυνάμεων απoκόλλησής τους από την επιφάνεια τεχνητών υλικών. Ως βασικό εργαλείο για τα πειράματα χρησιμοποιήθηκε το Μικροσκόπιο Ατομικής Δύναμης (AFM), με το οποίο ελήφθησαν εικόνες από δείγματα μέσα σε υδατικό διάλυμα καθώς και καταγράφηκαν οι δυνάμεις αλληλεπίδρασης μορίων με επιφάνειες. Η πρωτεΐνη ινωδογόνο επιλέχθηκε για τη μελέτη εξαιτίας της σημασίας της για τη βιοσυμβατότητα των βιοϋλικών, καθώς ο πολυμερισμός της σε ινώδες είναι δυνατό να καταλήξει στο σχηματισμό θρόμβων. Ως υποστρώματα προσρόφησης χρησιμοποιήθηκαν η μίκα και το γυαλί λόγω της απαίτησης λείων επιφανειών για το AFM. Το πρώτο στάδιο της έρευνας περιελάμβανε την ποσοτικοποίηση της προσρόφησης μεμονωμένων μορίων ινωδογόνου πάνω σε επιφάνεια μίκας υπό μεταβλητές συνθήκες ιοντικής ισχύος και pH. Στόχος ήταν η κατανόηση του τρόπου, μέσω του οποίου η κατανομή των ηλεκτροστατικών φορτίων, τόσο στα πρωτεϊνικά μόρια όσο και στην επιφάνεια, επηρεάζει την αλληλεπίδρασή τους. Η μελέτη της προσρόφησης με μεμονωμένα πρωτεϊνικά μόρια, αντί του συνήθους συμπαγούς στρώματος, προτιμήθηκε για να αποφευχθεί η παρεμβολή των πλευρικών αλληλεπιδράσεων μεταξύ των μορίων στο τελικό αποτέλεσμα. Έτσι, οι εικόνες, οι οποίες ελήφθησαν με την τεχνική της ταλαντούμενης ακίδας σε φωσφορικό ρυθμιστικό διάλυμα και η στατιστική ανάλυση της επιφανειακής κάλυψης στις διάφορες συνθήκες διαλύματος έδειξαν ότι η ισορροπία των απωστικών ηλεκτροστατικών δυνάμεων και των δυνάμεων ενυδάτωσης με τις ελκτικές van der Waals καθορίζει την έκβαση της προσρόφησης από τα πρώτα στάδιά της, όταν δηλαδή την επιφάνεια προσεγγίζουν ανεξάρτητα πρωτεϊνικά μόρια. Περαιτέρω διερεύνηση του ρόλου της ιοντικής ισχύος και του pH στην αλληλεπίδραση ινωδογόνου‐επιφανειών επιχειρήθηκε με μέτρηση της δύναμης έλξης και αποκόλλησης ακίδων του AFM από δείγματα μίκας. Οι ακίδες είχαν προηγουμένως τροποποιηθεί με μικροσφαιρίδια, στην επιφάνεια των οποίων είχε προσδεθεί ομοιοπολικά, με κατάλληλη χημική διαδικασία, ένα στρώμα μορίων ινωδογόνου. Οι καμπύλες προσέγγισης‐απομάκρυνσης, οι οποίες περιγράφηκαν θεωρητικά με βάση το μοντέλο DLVO, απέδειξαν την ύπαρξη συσχέτισης ανάμεσα στις μετρούμενες δυνάμεις και το βαθμό προσρόφησης στις διάφορες συνθήκες. Ειδικότερα οι μετρήσεις σε pH 3.5 έδωσαν ισχυρές ενδείξεις για αλλαγές της μοριακής διάταξης του ινωδογόνου, οι οποίες μπορούν να συσχετιστούν με τις ενζυμικά καταλυόμενες αναδιατάξεις της δομής του κατά το σχηματισμό του ινώδους. Η τελευταία ομάδα των πειραμάτων επικεντρώθηκε στη μέτρηση της δύναμης αποκόλλησης μεμονωμένων μορίων ινωδογόνου από την επιφάνεια γυαλιού. Για το σκοπό αυτό η πρωτεΐνη προσδέθηκε ομοιοπολικά στις ακίδες του AFM μέσω αλυσίδων πολυαιθυλενικής γλυκόλης (PEG), αφού πρώτα εξετάστηκαν τρεις διαφορετικές τεχνικές επιφανειακής χημικής τροποποίησης (3‐ αμινοπροπυλο‐τριαιθοξυσιλάνιο, αιθανολαμίνη και 3‐αμινοπροπυλο‐διμεθυλ‐αιθοξυσιλάνιο). Ο εντοπισμός στο σύνολο των καμπύλων, που συλλέχθηκαν, εκείνων, οι οποίες αντιπροσωπεύουν αποκόλληση ενός μόνο πρωτεϊνικού μορίου, στηρίχθηκε στα χαρακτηριστικά των καμπύλων τάνυσης των ανεξάρτητων μορίων ινωδογόνου, οι οποίες και προσαρμόστηκαν από το μοντέλο “Worm‐Like Chain”. Η επεξεργασία των πειραματικών καμπύλων και ο προσδιορισμός της δύναμης αποκόλλησης σε κάθε μία έγινε με τη βοήθεια πρωτότυπου κώδικα στη Matlab. Οι μετρηθείσες δυνάμεις ομαδοποιήθηκαν με κριτήριο την ταχύτητα αποκόλλησης και εξετάστηκε κατά πόσο η θεωρία των Bell και Evans μπορεί να χρησιμοποιηθεί για την περιγραφή της δυναμικής των δεσμών, οι οποίοι σχηματίζονται μεταξύ του ινωδογόνου και του υποστρώματος του γυαλιού. Τέλος, προτάθηκαν δύο θεωρήσεις για τη φυσική ερμηνεία των πειραματικών καμπύλων, οι οποίες παρουσίαζαν πολλαπλά συμβάντα αποκόλλησης, η θεώρηση της διαδοχικής διάσπασης δεσμών μιας μοναδικής πρωτεϊνικής αλυσίδας με το υπόστρωμα και η θεώρηση των παράλληλων μορίων. Συμπερασματικά η διατριβή αυτή παρουσιάζει ολοκληρωμένα τη χρήση του AFM για τη μελέτη, στο νανοεπίπεδο, της συμπεριφοράς ανεξάρτητων πρωτεϊνικών μορίων σε διεπιφάνειες. Η πρωτοτυπία της έγκειται στη μέτρηση της δύναμης αποκόλλησης μεμονωμένων μορίων ινωδογόνου από την επιφάνεια. Η επέκταση της τεχνικής αυτής σε χημικά τροποποιημένες και σαφώς χαρακτηρισμένες επιφάνειες καθώς και χρήση άλλων πρωτεϊνών μπορεί να φέρει την τεχνική αυτή κοντά σε ακριβέστερες εφαρμογές ελέγχου της βιοσυμβατότητας χρησιμοποιούμενων από την ιατρική υλικών. / The aim of this doctoral thesis was the study of the mechanisms of protein adsorption and the measurement of the detachment forces of proteins from surfaces. The experiments were conducted with the Atomic Force Microscope (AFM), with which images of adsorbed proteins were obtained in liquid and protein‐surface interaction forces were recorded. The study was focused on fibrinogen, a protein the behavior of which on biomaterial surfaces is critical for their biocompatibility assessment, since its polymerization into fibrin leads to the formation clots. Mica and glass were used as substrates for adsorption due to the restrictions imposed by AFM techniques for smooth surfaces. In the first set of experiments we tried to quantify the adsorption of single protein molecules on mica at different conditions of pH and ionic strength. The objective was to clarify the role of electrostatic charge distribution both on the surface and the molecules upon their interaction. Single protein molecules were studied instead of confluent monolayers in order to exclude the effect of lateral intermolecular interactions in the measurements. The images acquired with tapping mode in phosphate buffered saline and the statistical analysis of the surface coverage at the various conditions indicated that the balance between the repulsive electrostatic or hydration forces and the attractive van der Waals forces determines adsorption from its very early steps, when individual molecules approach the surface. To further investigate the pH and ionic strength effect in fibrinogen‐surface interaction, the force of attraction and detachment of colloid probes from mica surface was measured. The probes were constructed from silica microspheres attached to AFM cantilevers and were modified with a fibrinogen layer covalently bound to their surface. The approach‐retract curves, which were fitted by the DLVO model, proved that the measured interaction forces, can be correlated with the degree of adsorption at the various conditions. Particularly measurements at pH 3.5 offered evidence of fibrinogen conformational changes, which may be related to enzymically catalyzed restructurings during the formation of fibrin. The last set of experiments was focused on the measurement of the detachment force of single fibrinogen molecules from glass surfaces. For this purpose the protein was covalently bound to AFM tips, through polyethylene glycol linkers, after three different methods of surface chemical modification had been tested (3‐aminopropyl(triethoxysilane), ethanolamine, 3‐ aminopropyl(dimethylethoxysilane)). The experimental curves representing single molecule detachment were identified from the characteristic stretching curves of the protein chains which were fitted by the Worm‐Like Chain model. For the automatic processing of force data an algorithm was written in Matlab. Then the measured rupture forces were grouped according to the loading rate and an attempt was made to describe the dynamics of fibrinogen‐substrate bindings with the Bell‐Evans theory. Finally, two models were suggested for the physical interpretation of curves with multiple rupture events. The first refers to successive ruptures of multiple connections of a single fibrinogen molecule with the substrate, while the second to parallel molecules stretched between the tip and the substrate. In conclusion this thesis demonstrated in detail the use of AFM for the study, at the nanoscale, of protein molecules at interfaces. An important novelty was the measurement of the rupture force of single protein molecules from surfaces. Extension of the tested techniques to chemically modified and well‐characterized surfaces as well as to different proteins can be applied for the accurate prediction of realistic biomaterial biocompatibility.

<p><span lang="EN-GB" style="font-size:12.0pt / font-family:&quot / Times New Roman&quot / ,&quot / serif&quot / mso-fareast-font-family:&quot / Times New Roman&quot / mso-ansi-language:EN-GB / mso-fareast-language: EN-ZA">Literature shows that cataracts are the leading cause of blindness globally and nationally. Retinal detachment has also been a substantial problem both globally and nationally. Both of these conditions are prevalent in patients of 50 years and older. The treatment for both conditions is for surgery to be performed. In the Western Cape the three leading hospitals do not have ophthalmic pre-operative and post-operative protocols<span style="mso-bidi-font-weight:bold">.</span>Review question:What are the best practices to manage pre-operative and post-operative nursing care in patients waiting for cataract and retinal detachment surgery? bjectives:1. To determine the best practice in pre-operative and post-operative care in patients who have undergone cataract and/or retinal detachment surgery regarding: health education offered by nurses, counselling to prevent psychological effects, and positioning to prevent physical complications. 2. To develop a framework based on systematic reviews for pre-operative and post-operative ophthalmic nursing care in South Africa. Methodology: </span><span lang="EN-GB" style="font-size: 12.0pt / font-family:&quot / Times New Roman&quot / ,&quot / serif&quot / mso-ansi-language:EN-GB">A systematic review using the guide by the Centre for Reviews and Dissemination was done, and <span style="mso-bidi-font-weight:bold">studies were </span>identified by searching various electronic databases and visually scanning reference lists from the relevant studies. Studies that were included were evidence-based. All study types were considered and the studies were selected based on the title and, where available, the abstract. These were then assessed against the inclusion criteria. A narrative synthesis was used. Finally the evidence was summarised and a framework was drawn up, focusing on pre-operative and post-operative nursing care for cataract and retinal detachment surgery</span></p> <p>&nbsp / </p>