Ligand influence on nanoparticle agglomeration in flow

Having emerged from basic science, nanoparticles are now applied in many fields of science and technology. Agglomeration is ubiquitous and occurs, often inadvertently, in the formulation of particle-polymer mixtures, during the chemical functionalisation of nanoparticles and even during storage. This dissertation outlines recent studies on the agglomeration behaviour of different gold nanoparticle types. A modular fluidic system was specifically designed to perform the experiments. It enables the preparation of a steady flow of stable or unstable nanoparticle samples. This allows to observe different steps of a time-dependant process in steady state over practically arbitrary times in flow. These capabilities are used in this research to investigate the agglomeration of destabilised aqueous gold nanoparticles, reassess the solvent induced self-assembly of unpolar gold nanoparticles and examine the shear-assisted orientation of gold nanowires. The performance of the system is demonstrated and new insights on the influence of solvent conditions, temperature and the flow field are presented. The relevant process parameters as well as the microscopic interactions responsible for the structure formation mechanisms are discussed.Nanopartikel sind ihren Kinderschuhen in der Grundlagenforschung entwachsen und haben mittlerweile vielfältige Einsatzmöglichkeiten von der Forschung bis zur industriellen Anwendung. Agglomeration spielt in der Regel eine Rolle und tritt (gewollt oder ungewollt) bei der Herstellung von Partikel-Polymerkompositen, der Oberflächenmodifizierung von Partikeln und selbst der Lagerung auf. In dieser Dissertation werden neue Studien zur Agglomeration verschiedener Klassen von Gold-Nanopartikeln vorgestellt. Ein modulares Fluidiksystem wurde speziell für die hier präsentierten Versuche entworfen. Damit kann ein kontinuierlicher Fluss aus stabilen und speziell auch destabilisierten Nanopartikelproben erzeugt werden. Dadurch wird es möglich, verschiedene Stufen einer zeitlich veränderlichen Reaktion im Fließgleichgewicht zu analysieren. Dabei ist die Integrationszeit grundsätzlich nicht beschränkt. Mittels dieser Möglichkeiten wurde in dieser Forschungsarbeit die Agglomeration von destabilisierten, wässrigen Gold-Nanopartikeln untersucht, die Selbstorganisation unpolarer Partikel in geordnete Überstrukturen neu beleuchtet und die Ausrichtung von Gold-Nanodrähten in einer Scherströmung analysiert. Die dazugehörigen Prozessparameter sowie die zugrunde liegenden mikroskopischen Wechselwirkung sollen in dieser Arbeit erörtert werden

Ligand influence on nanoparticle agglomeration in flow

Having emerged from basic science, nanoparticles are now applied in many fields of science and technology. Agglomeration is ubiquitous and occurs, often inadvertently, in the formulation of particle-polymer mixtures, during the chemical functionalisation of nanoparticles and even during storage. This dissertation outlines recent studies on the agglomeration behaviour of different gold nanoparticle types. A modular fluidic system was specifically designed to perform the experiments. It enables the preparation of a steady flow of stable or unstable nanoparticle samples. This allows to observe different steps of a time-dependant process in steady state over practically arbitrary times in flow. These capabilities are used in this research to investigate the agglomeration of destabilised aqueous gold nanoparticles, reassess the solvent induced self-assembly of unpolar gold nanoparticles and examine the shear-assisted orientation of gold nanowires. The performance of the system is demonstrated and new insights on the influence of solvent conditions, temperature and the flow field are presented. The relevant process parameters as well as the microscopic interactions responsible for the structure formation mechanisms are discussed.Nanopartikel sind ihren Kinderschuhen in der Grundlagenforschung entwachsen und haben mittlerweile vielfältige Einsatzmöglichkeiten von der Forschung bis zur industriellen Anwendung. Agglomeration spielt in der Regel eine Rolle und tritt (gewollt oder ungewollt) bei der Herstellung von Partikel-Polymerkompositen, der Oberflächenmodifizierung von Partikeln und selbst der Lagerung auf. In dieser Dissertation werden neue Studien zur Agglomeration verschiedener Klassen von Gold-Nanopartikeln vorgestellt. Ein modulares Fluidiksystem wurde speziell für die hier präsentierten Versuche entworfen. Damit kann ein kontinuierlicher Fluss aus stabilen und speziell auch destabilisierten Nanopartikelproben erzeugt werden. Dadurch wird es möglich, verschiedene Stufen einer zeitlich veränderlichen Reaktion im Fließgleichgewicht zu analysieren. Dabei ist die Integrationszeit grundsätzlich nicht beschränkt. Mittels dieser Möglichkeiten wurde in dieser Forschungsarbeit die Agglomeration von destabilisierten, wässrigen Gold-Nanopartikeln untersucht, die Selbstorganisation unpolarer Partikel in geordnete Überstrukturen neu beleuchtet und die Ausrichtung von Gold-Nanodrähten in einer Scherströmung analysiert. Die dazugehörigen Prozessparameter sowie die zugrunde liegenden mikroskopischen Wechselwirkung sollen in dieser Arbeit erörtert werden

Die Verbrecher von morgen? Rezension zu "Personenbezogenes Predictive Policing. Kriminalwissenschaftliche Untersuchung über die Automatisierung der Kriminalprognose" von Lucia M. Sommerer

Lucia M. Sommerer: Personenbezogenes Predictive Policing: Kriminalwissenschaftliche Untersuchung über die Automatisierung der Kriminalprognose. Baden-Baden: Nomos 2020. 978-3-8487-6233-

Self-assembly of gold nanoparticles at the oil-vapor interface: from mono- to multilayers

Alkylthiol-coated gold nanoparticles spontaneously segregate from dispersion in toluene to the toluene-vapor interface. We show that surface tension drops during segregation with a rate that depends on particle concentration. Mono- and multilayers of particles form depending on particle concentration, time, and temperature. X-ray reflectometry indicates fast monolayer formation and slow multilayer formation. A model that combines diffusion-limited segregation driven by surface energy and heterogeneous agglomeration driven by dispersive van der Waals particle interactions is proposed to describe film formation

Multivalent bonds in self-assembled bundles of ultrathin gold nanowires

Ultrathin gold nanowires are unusual colloidal objects that assemble into bundles with line contacts between parallel wires. Each molecule in the contact line interacts with many ligand and solvent molecules. We used X-ray scattering and electron microscopy to study how these interactions control assembly

Neighborhood crime reduction interventions and perceived livability: A virtual reality study on fear of crime

High levels of Fear of Crime (FOC) are associated with people engaging with their community less, lower use of public spaces, and a general sense of overall anxiety. In short, such fear may reduce the livability of an area. The primary goal of this research was to examine the potential consequences of environmental interventions intended to reduce crime on FOC and perceived livability of the area. Using immersive Virtual Reality (VR) technology, in two studies we examined how environmental interventions in residential neighborhoods influence FOC. In Study 1, we examined how motion-activated, dynamic street lighting and sound may decrease FOC. In Study 2, we applied an adapted ‘watching eyes’ intervention and examined how it may inadvertently increase FOC in a neighborhood. In Study 1 the intervention did not affect feelings of safety. In Study 2, the ‘watching eyes’ intervention indirectly increased FOC via feelings of being watched. In the Discussion, we highlight the importance of better understanding the boundary conditions of such environmental interventions

Selective endocytosis controls slit diaphragm maintenance and dynamics in Drosophila nephrocytes

The kidneys generate about 180 liters of primary urine per day by filtration of plasma. An essential part of the filtration barrier is the slit diaphragm, a multiprotein complex containing nephrin as major component. Filter dysfunction typically manifests with proteinuria and mutations in endocytosis regulating genes were discovered as causes of proteinuria. However, it is unclear how endocytosis regulates the slit diaphragm and how the filtration barrier is maintained without either protein leakage or filter clogging. Here we study nephrin dynamics in podocyte-like nephrocytes of Drosophila and show that selective endocytosis either by dynamin- or flotillin-mediated pathways regulates a stable yet highly dynamic architecture. Short-term manipulation of endocytic functions indicates that dynamin-mediated endocytosis of ectopic nephrin restricts slit diaphragm formation spatially while flotillin-mediated turnover of nephrin within the slit diaphragm is needed to maintain filter permeability by shedding of molecules bound to nephrin in endosomes. Since slit diaphragms cannot be studied in vitro and are poorly accessible in mouse models, this is the first analysis of their dynamics within the slit diaphragm multiprotein complex. Identification of the mechanisms of slit diaphragm maintenance will help to develop novel therapies for proteinuric renal diseases that are frequently limited to symptomatic treatment

Tissue-preserving treatment with non-invasive physical plasma of cervical intraepithelial neoplasia—a prospective controlled clinical trial

ObjectiveCervical cancer represents the fourth leading cause of cancer among women and is associated with over 311,000 annual deaths worldwide. Timely diagnosis is crucial given the lengthy pre-cancerous phase, which is typified by cervical intraepithelial neoplastic lesions. However, current treatment methods are often tissue-destructive and can be accompanied by severe side effects. To address these concerns, our study introduces a novel, gentle approach for the tissue-preserving treatment of CIN lesions.ResultsWe present findings of a controlled, prospective, single-armed phase IIb clinical trial performed at the Department for Women’s Health, Tübingen, Germany. From September 2017 to March 2022 we assessed 570 participants for study eligibility. Of the screened patients, 63 participants met with CIN1/2 lesions met the inclusion criteria and were treated with non-invasive physical plasma (NIPP). Assessment of treatment efficacy was based on a comprehensive analysis of histological and cytological findings, along with high-risk HPV infection load at 3 and 6 months post-treatment. Comparative analyses were performed retrospectively with data obtained from 287 untreated patients in the control group. Our findings indicate that patients treated with NIPP experienced an 86.2% rate of full remission, along with a 3.4% rate of partial remission of CIN lesions, which compares favorably to the control group’s rates of 40.4% and 4.5%, respectively. Additionally, we observed a twofold reduction in high-risk HPV infections following NIPP treatment. Minor side effects were observed, such as mild pain during treatment and short-term smear bleeding or increased vaginal discharge within 24 h after treatment. Given the experimental nature of NIPP treatment and the availability of established standard treatments, our study was designed as a non-randomized study.ConclusionNIPP treatment offers a highly flexible and easy-to-apply method for treating pre-cancerous CIN1/2 lesions. This non-invasive approach is notable for its tissue-preserving nature, making it a promising alternative to current excisional and ablative treatments. CIN1/2 lesions were employed as preliminary in vivo models for the targeted treatment of CIN3 lesions.Clinical trial registrationhttps://www.clinicaltrials.gov, identifier NCT03218436

Ligand influence on nanoparticle agglomeration in flow

Having emerged from basic science, nanoparticles are now applied in many fields of science and technology. Agglomeration is ubiquitous and occurs, often inadvertently, in the formulation of particle-polymer mixtures, during the chemical functionalisation of nanoparticles and even during storage.This dissertation outlines recent studies on the agglomeration behaviour of different gold nanoparticle types. A modular fluidic system was specifically designed to perform the experiments. It enables the preparation of a steady flow of stable or unstable nanoparticle samples. This allows to observe different steps of a time-dependant process in steady state over practically arbitrary times in flow.These capabilities are used in this research to investigate the agglomeration of destabilised aqueous gold nanoparticles, reassess the solvent induced self-assembly of unpolar gold nanoparticles and examine the shear-assisted orientation of gold nanowires. The performance of the system is demonstrated and new insights on the influence of solvent conditions, temperature and the flow field are presented. The relevant process parameters as well as the microscopic interactions responsible for the structure formation mechanisms are discussed

Collective efficacy in Australian and German neighborhoods: testing cross-cultural measurement equivalence and structural correlates in a multi-level SEM framework

In neighborhood research, the concept of collective efficacy has been particularly successful in capturing social cohesion and behavioral expectations among residents. Research has spread beyond the U.S. where it originated, and many studies from different countries have shown that collective efficacy is related to structural disadvantage in similar ways and affects outcomes as crime, education or health. However, methodological issues about measurement and modeling persist, and no study has yet investigated the cross-cultural measurement equivalence of this scale. We close this gap using two recent neighborhood surveys from Australia and Germany with large samples of respondents (N = ca. 12.800) and neighborhoods (N = ca. 440) in four cities. We employ multilevel structural equation modeling to test for measurement equivalence of collective efficacy across countries and to model its association with concentrated poverty, ethnic diversity, and residential stability. We find that the measurement of collective efficacy is metrically equivalent in both countries, modeling two latent factors on the respondent level—the two components informal social control and social cohesion/trust—but only one latent factor on the neighborhood level. Considering the relationship between the key correlates of collective efficacy, we find broad similarities but also substantial differences across contexts and compared to U.S. research, particularly concerning the role of ethnic diversity which has a stronger diminishing effect in Germany than in Australia. Possible explanations for these differences are discussed