Entwicklung, Charakterisierung und Anwendung von In-liquid-Elektronenabbildungs- und Beugungstechniken für die hochauflösende Strukturanalyse

Spotting the mesoscale structural dynamics of biochemical processes in vivo with atomic-level detail has been a great technological challenge. Since a majority of these occur naturally in the solution phase, techniques allowing in-liquid observations are particularly attractive to the scientific community. Even though spectroscopic techniques permit straightforward solution-phase measurements, they nevertheless fail to provide direct structural information. Scattering techniques are mostly applied for such applications. In-liquid sample preparation techniques for electrons, which offer a greater scattering cross-section compared to X-rays, is quite challenging. The low penetration depth of the electrons imposes an additional constraint on the sample thickness. This thesis presents the author’s contribution towards the modification of the existing liquid cell technology for in-liquid real-space imaging and diffraction. Silicon based micro- and nanofabrication technology has been used to produce 20 nm thin silicon nitride windows for nanofluidic cells. The behaviour of nanofluidic cells under vacuum was characterized using a thin-film interferometer. These measurements provided insight into the deformation occurring in the silicon nitride windows, which resulted in an increase in specimen thickness. These issues led to the idea of the environmental liquid cell (ELC), where the environmental cell concept was combined with nanofluidic cell technology. The newly developed ELC method was shown to demonstrate controllable liquid thickness, which allowed imaging of gold nanoparticles, polystyrene beads, and ferritin molecules with sub-nm spatial resolution. The same technique was utilized to acquire diffraction from liquid water at room temperature. The scattering data provided information about the O•••H and O•••O pair distribution function, from which the coordination number was extracted and the values were 1.91 and 5,01, respectively. Further, the number of hydrogen bonds per water molecule was computed to be 3.8, implying a nearly tetrahedral structure of water. Despite delivering very promising results, the ELC technique still cannot be used for phase contrast imaging which require windows as thin as 10 nm. Moreover, the windows in the ELC are prone to failure. These shortcomings prompted the design idea of the elliptical multi-window liquid cell for phase-contrast imaging.Die Untersuchung von Strukturdynamik biochemischer Prozesse mit atomarer räumlicher Auflösung in vivo ist eine große technische Herausforderung. Da diese Prozesse meist in wässrigem Milieu auftreten sind Techniken, die Beobachtungen in flüssiger Form ermöglichen, für Wissenschaftler besonders attraktiv. Auch wenn spektroskopische Techniken einfache Messungen in der Lösungsphase erlauben, liefern sie dennoch keine direkten Strukturinformationen. Für solche Anwendungen werden meist Streuungstechniken eingesetzt. Präparationstechniken für flüssige Proben, welche mittels Elektronenmikroskopie oder Elektronenbeugung untersucht werden sollen, stellen im Vergleich zu den auf Röntgenstrahlen basierten Analogen eine große Herausforderung dar. Ein wesentlicher Grund hierfür ist der größere Streuquerschnitt der Elektronen, welcher zu einer geringeren Eindringtiefe führt und somit sehr dünne Proben erfordert. In dieser Arbeit wird der Beitrag des Autors zur Modifizierung der bestehenden Flüssigkeitszellentechnologie für die Realabbildung als auch Beugung von flüssigen Proben vorgestellt. Auf Silizium basierende Mikro- und Nanofabrikationstechnologien wurden eingesetzt, um 20 nm dünne Siliziumnitridfenster für Nanofluidikzellen herzustellen. Das Verhalten von Nanofluidikzellen unter Vakuum wurde mit Hilfe eines Dünnschichtinterferometers charakterisiert. Diese Messungen gaben Aufschluss über die in den Siliziumnitridfenstern auftretende Verformung, die zu einer unerwünschten Zunahme der Probendicke führte. Um dieses Problem zu umgehen, wurde die Idee der Umgebungsflüssigkeitszelle (ELC) konzipiert. Hierbei handelt es sich im Wesentlichen um eine Kombination von Ansätzen herkömmlicher environmental Transmissionselektronenmikroskopie mit der Nanofluidik-Zellentechnologie. Die neu entwickelte ELC-Methode erlaubte die Verwirklichung eines Flüssigkeitsfilms kontrollierbarer Dicke, was seinerseits die Abbildung von Goldnanopartikeln, Polystyrolkügelchen und Ferritinmolekülen mit einer räumlichen Auflösung von besser als einem Nanometer ermöglichte. Dieselbe Technik wurde zur Erfassung der Beugung an flüssigem Wasser bei Raumtemperatur verwendet. Die Streudaten lieferten Informationen über die O---H- und O---O-Paar-Verteilungsfunktion, aus denen die Koordinationszahl extrahiert wurde und die Werte 1,91 bzw. 5,01 betrugen. Weiterhin wurde berechnet, dass die Anzahl der Wasserstoffbrückenbindungen pro Wassermolekül 3,8 beträgt, was eine nahezu tetraedrische Struktur des Wassers impliziert. Obwohl die ELC-Technik sehr vielversprechende Ergebnisse liefert, konnte sie bisher noch nicht für die Phasenkontrast-Bildgebung eingesetzt werden. Hierfür sind Siliziumnitridfenster von etwa 10 nm Dicke erforderlich. Darüber hinaus sind die soweit genutzten Fenster in der ELC fragil, und somit unzuverlässig. Diese Unzulänglichkeiten gaben den Anstoß zu der Konstruktionsidee der elliptischen Mehrfenster-Flüssigkeitszelle für die Phasenkontrast-Bildgebung

Entwicklung, Charakterisierung und Anwendung von In-liquid-Elektronenabbildungs- und Beugungstechniken für die hochauflösende Strukturanalyse

Spotting the mesoscale structural dynamics of biochemical processes in vivo with atomic-level detail has been a great technological challenge. Since a majority of these occur naturally in the solution phase, techniques allowing in-liquid observations are particularly attractive to the scientific community. Even though spectroscopic techniques permit straightforward solution-phase measurements, they nevertheless fail to provide direct structural information. Scattering techniques are mostly applied for such applications. In-liquid sample preparation techniques for electrons, which offer a greater scattering cross-section compared to X-rays, is quite challenging. The low penetration depth of the electrons imposes an additional constraint on the sample thickness. This thesis presents the author’s contribution towards the modification of the existing liquid cell technology for in-liquid real-space imaging and diffraction. Silicon based micro- and nanofabrication technology has been used to produce 20 nm thin silicon nitride windows for nanofluidic cells. The behaviour of nanofluidic cells under vacuum was characterized using a thin-film interferometer. These measurements provided insight into the deformation occurring in the silicon nitride windows, which resulted in an increase in specimen thickness. These issues led to the idea of the environmental liquid cell (ELC), where the environmental cell concept was combined with nanofluidic cell technology. The newly developed ELC method was shown to demonstrate controllable liquid thickness, which allowed imaging of gold nanoparticles, polystyrene beads, and ferritin molecules with sub-nm spatial resolution. The same technique was utilized to acquire diffraction from liquid water at room temperature. The scattering data provided information about the O•••H and O•••O pair distribution function, from which the coordination number was extracted and the values were 1.91 and 5,01, respectively. Further, the number of hydrogen bonds per water molecule was computed to be 3.8, implying a nearly tetrahedral structure of water. Despite delivering very promising results, the ELC technique still cannot be used for phase contrast imaging which require windows as thin as 10 nm. Moreover, the windows in the ELC are prone to failure. These shortcomings prompted the design idea of the elliptical multi-window liquid cell for phase-contrast imaging.Die Untersuchung von Strukturdynamik biochemischer Prozesse mit atomarer räumlicher Auflösung in vivo ist eine große technische Herausforderung. Da diese Prozesse meist in wässrigem Milieu auftreten sind Techniken, die Beobachtungen in flüssiger Form ermöglichen, für Wissenschaftler besonders attraktiv. Auch wenn spektroskopische Techniken einfache Messungen in der Lösungsphase erlauben, liefern sie dennoch keine direkten Strukturinformationen. Für solche Anwendungen werden meist Streuungstechniken eingesetzt. Präparationstechniken für flüssige Proben, welche mittels Elektronenmikroskopie oder Elektronenbeugung untersucht werden sollen, stellen im Vergleich zu den auf Röntgenstrahlen basierten Analogen eine große Herausforderung dar. Ein wesentlicher Grund hierfür ist der größere Streuquerschnitt der Elektronen, welcher zu einer geringeren Eindringtiefe führt und somit sehr dünne Proben erfordert. In dieser Arbeit wird der Beitrag des Autors zur Modifizierung der bestehenden Flüssigkeitszellentechnologie für die Realabbildung als auch Beugung von flüssigen Proben vorgestellt. Auf Silizium basierende Mikro- und Nanofabrikationstechnologien wurden eingesetzt, um 20 nm dünne Siliziumnitridfenster für Nanofluidikzellen herzustellen. Das Verhalten von Nanofluidikzellen unter Vakuum wurde mit Hilfe eines Dünnschichtinterferometers charakterisiert. Diese Messungen gaben Aufschluss über die in den Siliziumnitridfenstern auftretende Verformung, die zu einer unerwünschten Zunahme der Probendicke führte. Um dieses Problem zu umgehen, wurde die Idee der Umgebungsflüssigkeitszelle (ELC) konzipiert. Hierbei handelt es sich im Wesentlichen um eine Kombination von Ansätzen herkömmlicher environmental Transmissionselektronenmikroskopie mit der Nanofluidik-Zellentechnologie. Die neu entwickelte ELC-Methode erlaubte die Verwirklichung eines Flüssigkeitsfilms kontrollierbarer Dicke, was seinerseits die Abbildung von Goldnanopartikeln, Polystyrolkügelchen und Ferritinmolekülen mit einer räumlichen Auflösung von besser als einem Nanometer ermöglichte. Dieselbe Technik wurde zur Erfassung der Beugung an flüssigem Wasser bei Raumtemperatur verwendet. Die Streudaten lieferten Informationen über die O---H- und O---O-Paar-Verteilungsfunktion, aus denen die Koordinationszahl extrahiert wurde und die Werte 1,91 bzw. 5,01 betrugen. Weiterhin wurde berechnet, dass die Anzahl der Wasserstoffbrückenbindungen pro Wassermolekül 3,8 beträgt, was eine nahezu tetraedrische Struktur des Wassers impliziert. Obwohl die ELC-Technik sehr vielversprechende Ergebnisse liefert, konnte sie bisher noch nicht für die Phasenkontrast-Bildgebung eingesetzt werden. Hierfür sind Siliziumnitridfenster von etwa 10 nm Dicke erforderlich. Darüber hinaus sind die soweit genutzten Fenster in der ELC fragil, und somit unzuverlässig. Diese Unzulänglichkeiten gaben den Anstoß zu der Konstruktionsidee der elliptischen Mehrfenster-Flüssigkeitszelle für die Phasenkontrast-Bildgebung

Bone metastasis in breast cancer: The story of RANK-Ligand

AbstractThe primary cellular mechanism responsible for osteolytic bone metastases is osteoclastic activation. Preclinical models have shown that breast cancer cells can produce parathyroid hormone-related protein (PTHrP), and other osteolytic molecules, which stimulate excessive osteoclastic bone resorption and establishment of osteolytic lesions. It has been shown that PTHrP by itself cannot directly induce osteoclastic activation, but it mediates its effect through the transactivation of RANK-ligand (RANKL) gene on stromal and osteoblastic cells. Accordingly RANKL up-regulation has been considered as a prerequisite in virtually all conditions of cancer induced bone destruction. Hence, therapeutic targeting of RANKL seems to be a rational approach to treat or even to prevent the process of bone metastases.In this review, we will focus on the unique patho-physiological aspects related to the evolution of bone metastases in breast cancer, emphasizing the pivotal role of RANKL and some other key molecules in osteoclastic bone resorption. We will discuss the therapeutic interventions using bisphosphonates and RANKL inhibitors in patients with bone metastases and the outcome of this novel approach

A study of the Haor areas of Sylhet-Mymensing districts with ERTS imageries (winter crop estimation)

There are no author-identified significant results in this report

Impact of Cytotoxin-Associated Gene Product-A Positive Helicobacter Pylori Strains on Micro-albuminuria in Type 2 Diabetes

Introduction: Available data on the possible association between Helicobacter Pylori (H. pylori) infection and diabetes mellitus (DM) are contradictory. The prevalence of cytotoxin associated gene product A (cagA) positive H. pylori is high in Egypt. This study aims to examine its association with type 2 DM, and its effect on glycemic control and the occurrence of microalbuminuria. Methods: The study involved 98 dyspeptic type 2 diabetic patients and 102 dyspeptic non-diabetic subjects who underwent upper gastrointestinal tract endoscopy in Zagazig university hospital. H. pylori infection was diagnosed by histopathology and/or culture. The presence of cagA positive strains was confirmed by polymerase chain reaction (PCR) and gel electrophoresis. Fasting blood sugar (FBS), glycosylated hemoglobin (HbA1c) and urinary albumin excretion ratio (UAER) were compared between infected and non-infected diabetic patients. Results: Diabetic patients had similar age and gender distribution but significantly higher body mass index (BMI) compared to controls. The prevalence of H. pylori infection (54.1% versus 56.9%, P = 0.3) and the prevalence of cagA positive H. pylori strains (40.8% versus 36.3%, P =0.1) were not significantly different between the two groups. Diabetic patients infected with cagA positive H. pylori strains had higher mean FBS (199±22 versus 163±20, P=0.00), higher mean HbA1c (8.6±0.8 versus 6.3±0.8, P=0.00) and higher rate of microalbuminuria (67.5% versus 10.3%, P=0.00) than non infected diabetic patients. Conclusion: H. pylori infection with cagA positive strains was similarly common in dyspeptic diabetic patients and controls. It was associated with poorer glycemic control and higher rates of microalbuminuria in diabetic subjects. Key words: cagA positive strains; Diabetes mellitus; Helicobatcer pylori; Microalbuminuri

Recent Advances in Preparation and Testing Methods of Engine-Based Nanolubricants: A State-of-the-Art Review

Reducing power losses in engines is considered a key parameter of their efficiency improvement. Nanotechnology, as an interface technology, is considered one of the most promising strategies for this purpose. As a consumable liquid, researchers have studied nanolubricants through the last decade as potential engine oil. Nanolubricants were shown to cause a considerable reduction in the engine frictional and thermal losses, and fuel consumption as well. Despite that, numerous drawbacks regarding the quality of the processed nanolubricants were discerned. This includes the dispersion stability of these fluids and the lack of actual engine experiments. It has been shown that the selection criteria of nanoparticles to be used as lubricant additives for internal combustion engines is considered a complex process. Many factors have to be considered to investigate and follow up with their characteristics. The selection methodology includes tribological and rheological behaviours, thermal stability, dispersion stability, as well as engine performance. Through the last decade, studies on nanolubricants related to internal combustion engines focused only on one to three of these factors, with little concern towards the other factors that would have a considerable effect on their final behaviour. In this review study, recent works concerning nanolubricants are discussed and summarized. A complete image of the designing parameters for this approach is presented, to afford an effective product as engine lubricant

Determining the radial distribution function of water using electron scattering: A key to solution phase chemistry

High energy electron scattering of liquid water (H2O) at near-ambient temperature and pressure was performed in a transmission electron microscope (TEM) to determine the radial distribution of water, which provides information on intra- and intermolecular spatial correlations. A recently developed environmental liquid cell enables formation of a stable water layer, the thickness of which is readily controlled by pressure and flow rate adjustments of a humid air stream passing between two silicon nitride (Si3N4) membranes. The analysis of the scattering data is adapted from the x-ray methodology to account for multiple scattering in the H2O:Si3N4 sandwich layer. For the H2O layer, we obtain oxygen–oxygen (O–O) and oxygen–hydrogen (O–H) peaks at 2.84 Å and 1.83 Å, respectively, in good agreement with values in the literature. This demonstrates the potential of our approach toward future studies of water-based physics and chemistry in TEMs or electron probes of structural dynamics

The Effectiveness of Using Word Expert Strategy in Vocabulary to the First Grade Students of SMKN 2 Bungoro Pangkep Regency

The objectives of this research were to find out the effectiveness of using Word Expert Strategy in teaching vocabulary to the first grade students’ of SMKN 2 Bungoro Pangkep Regency. This research employed quasi-experimental design with two group pre-test and post-test design. There were two variables in this research; they were independent variable (The Effectiveness of Using Word Expert Strategy) and dependent variable (Students Vocabulary). There was kind of instrument in this research, that was test. Test was used in pre-test and post-test. The data indicated that there was a significant difference between the students’ post-test in experimental class and that in control class. So, the researcher concluded that using word expert strategy was effective in teaching vocabulary

CD10 and osteopontin expression in dentigerous cyst and ameloblastoma

<p>Abstract</p> <p>Aims and Objectives</p> <p>To investigate the expression of CD10 and osteopontin in dentigerous cyst and ameloblastoma and to correlate their expression with neoplastic potentiality of dentigerous cyst and local invasion and risk of local recurrence in ameloblastoma.</p> <p>Methods</p> <p>CD10 and osteopontin expression was studied by means of immunohistochemistry in 9 cases of dentigerous cysts (DC) and 17 cases of ameloblastoma. There were 7 unicystic ameloblastoma (UCA) and 10 multicystic ameloblastoma (MCA). Positive cases were included in the statistical analysis, carried on the tabulated data using the Open Office Spreadsheet 3.2.1 under Linux operating system. Analysis of variance and correlation studies were performed using "R" under Linux operating system (R Development Core Team (2010). Tukey post-hoc test was also performed as a pair-wise test. The significant level was set at 0.05.</p> <p>Results</p> <p>High CD10 and osteopontin expression was observed in UCA and MCA, and low CD10 and osteopontin expression was observed in DC. Significant correlation was seen between CD10 and osteopontin expression and neoplastic potentiality of DC and local invasion and risk of recurrences in ameloblastoma.</p> <p>Conclusions</p> <p>In DC, high CD10 and osteopontin expression may indicate the neoplastic potentiality of certain areas. In UCA & MCA, high CD10 and osteopontin expression may identify areas with locally invasive behavior and high risk of recurrence.</p