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A novel nanocompartment system named Synthosome for biotechnological applications
No full textThe functionalized nanocompartment system, Synthosome, has been developed for putative biotechnological applications. A Synthosome is a hollow sphere consisting of a mechanically stable vesicle with a block copolymer membrane and an engineered transmembrane protein acting as the selective gate. Among other functions, the interior contains an enzyme catalyzing a reaction or a charged macromolecule species as trap for compounds. Two areas of application were targeted as proof of principle: A) Selective product recovery in nanocompartments and B) Enzymatic conversion in nanocompartments. Selective recovery of negatively charged compounds has been achieved in the example of sulforhodamine B by using positively charged polylysine molecules as a trap inside the nanocompartment. Conversion in nanocompartments has been achieved by 3,3',5,5'-tetramethylbenzidine oxidation employing horseradish peroxidase (HRP). In the second part of this thesis, the encapsulation of nanophosphor particles in Synthosomes for selective recovery of single stranded DNA is reported. The nanophosphors based FRET system presents to our knowledge the first use of polymer vesicles for monitoring DNA translocation through a polymer mimic of a biological membrane. Four channel proteins (OmpF, FhuA and two engineered FhuA variants) were investigated by time resolved fluorescence (TRF) measurements for their ability to translocated single stranded DNA
Significance of cathepsins B, D and L for homeostasis of the small intestine
No full textThe role of cathepsins in normal and traumatized small intestine was investigated in this project. In cathepsin-deficient mice, an altered intestine morphology was observed. In addition, an over-expression of mucosal plasma membrane proteins and intestinal extracellular matrix proteins, together with an altered localization of Na+/K+-ATPase were detected in situ in these mice, suggesting that cathepsins B and L are important for the organization of normal intestine architecture as well as maintaining normal deposition and turn-over of enterocyte surface and of extracellular matrix proteins. In mouse and rat models of standardized small intestine trauma, we investigate whether released cathepsins contribute to the initial phase in onset of post-traumatic ileus. The protein levels together with activities of cathepsins B, D and L were analyzed in intestinal tissue extracts at different time intervals after trauma. In both species, significantly increased cathepsin B occurred in the initial phase after trauma. The localized release of cathepsin B which resulted in increased extracellular proteolytic activity of cathepsin B was verified in conditioned media of squeezed intestinal epithelial cells in vitro. Hence, cathepsin B seemed to be the only of the investigated proteases that could play an important role during initial post-traumatic stages. Morphological analysis showed an increased labeling of cathepsin B at surface of cells in the basal lamina, suggesting that infiltrating cells most likely contributed to increased expression and activities of mucosal cathepsin B after trauma. Moreover, partial or total degradation of main intestinal epithelial and extracellar matrix proteins was observed by biochemistry and by morphology in tissue extracts at initial stages after trauma, which was most possibly caused by the released cathepsin B
A self-concept measure of personality growth : self-concept maturity (SCM) : development, validation, and age effect
No full textIt was the primary goal of this work to develop and validate an indirect and efficient instrument of personality growth that could overcome the typical difficulties of current alternative measures, that is, the problem of social desirability commonly associated with self-report, or costly and time-intensive evaluation procedures. As a theoretical background, literature on the self-concept as well as on personality growth was reviewed. Five self-concept facets were identified as theoretically meaningful indicators of personality growth, namely complexity, integration, affect balance, self-esteem, and value orientation. A modified version self-complexity questionnaire by Linville (1985, 1987) and a part of the Schwartz Value Survey (1992) were used to assess these. Because it was assumed that only a certain combination of the five self-concept facets represented an appropriate operationalization of personality growth, a profile prototype of personality growth was formulated along the lines of the five facets. The similarity of an individual's self-concept profile with this prototype in turn was assumed to reflect his/her level of personality growth or self-concept maturity (SCM). 167 adults completed the instrument as well as various other measures. 78 of the participants were older adults (aged 60-80 years) and 89 younger adults (aged 20-40 years). SCM revealed a high convergent validity with other well-established variables of personality growth and considerable discriminant validity with measures of adjustment. Self- and life reflection was a further significant predictor of SCM, while life events only significantly contributed to SCM when accompanied by a high degree of self- and life reflection. SCM was uncorrelated with chronological age and - against the hypotheses - also with intelligence. Reasons for minor deviations of findings from expectations, as well as possible improvements of the instrument and limitations of the study are discussed.Im Mittelpunkt dieser Arbeit stand das Ziel, eine indirekte und effiziente Methode zur Messung von Persönlichkeitswachstum zu entwickeln und zu validieren, welches die üblichen Probleme von in diesem Bereich verfügbaren Instrumenten, wie hohe soziale Erwünschtheit oder hoher Auswertungsaufwand umgehen kann. Als theoretischer Hintergrund wurde Literatur aus dem Bereich der Selbstkonzeptforschung und dem Bereich der Persönlichkeitswachstumsforschung herangezogen. Es wurden fünf Komponenten des Selbstkonzepts als Indikatoren von Persönlichkeitswachstum identifiziert, nämlich Komplexität, Integration, emotionale Balance, Selbstwert, und Werteorientierung. Diese wurden mittels einer adaptierten Form des Selbstkomplexitätsfragebogens von Linville (1985, 1987) und der Werteskala von Schwartz (1992) erfasst. Weil angenommen wurde, dass nur eine bestimmte Kombination der fünf Selbstkonzeptkomponenten Persönlichkeitswachstum widerspiegeln würde, wurde ein Profil formuliert, das als prototypisch für ein hohes Ausmaß von Persönlichkeitswachstum angesehen wurde. Die Ähnlichkeit eines individuellen Selbstkonzeptprofils mit diesem Prototypen wurde als ein Maß des Persönlichkeitswachstum bzw. der Selbstkonzeptreife (SKR) dieser Person definiert. 89 jüngere (20-40 Jahre) und 78 ältere Erwachsene (60-80 Jahre) füllten den SKR-Fragebogen und weitere Maße aus. Die Ergebnisse zeigen eine hohe konvergente Validität von SKR mit andern Maßen von Persönlichkeitswachstum sowie eine deutliche diskriminante Validität in Bezug auf Maße der Adaptivität. Selbst- und Lebensreflektion waren weitere signifikante Prädiktoren von SKR, während kritische Lebensereignisse nur unter der Bedingung eines hohen Ausmaßes von Selbst- und Lebensreflektion zu SKR beitrugen. Es keine Korrelation zwischen SKR und chronologischem Alter und – entgegen der Hypothesen - Intelligenz. Gründe für Diskrepanzen zwischen den ursprünglichen Annahmen und den Ergebnissen sowie Grenzen der Studie werden diskutiert
Cathepsins L and V in human keratinocytes
No full textIn human skin, three cysteine cathepsins are important for the homeostasis of epidermis. Cathepsin B is secreted by keratinocytes participating in the ECM remodeling contributing to the active migration of keratinocytes during the regeneration phase of keratinocytes after wounding. Cathepsin L is important for the regulation of keratinocyte proliferation and its deficiency in mice results in a strong phenotype characterized by a hyperproliferation of keratinocytes and a periodic hair loss. In contrast, cathepsin V is highly expressed in the Str. corneum participating in the extracellular degradation of desmosomes. Whereas human cells express both, cathepsins L and V, the mouse genome encodes for cathepsin L, only. Transgenic expression of human cathepsin V is able to rescue the skin phenotype of cathepsin L-deficient mice. Therefore, we hypothesized that cathepsins L and V are important for the proliferation and differentiation of keratinocytes occurring during wound healing of human skin. The human keratinocyte cell line HaCaT was used as an in vitro model system to observe the cellular response of human keratinocytes during the regeneration phase after wounding. Cathepsin V expression was up-regulated in cells within the first six hours after wounding which is two hours before HaCaT cells start proliferating as indicated by expression of the proliferation marker Ki-67. Due to wounding, the expression of cathepsin L remained unaltered. Additionally, immunolabeling studies revealed differential localization patterns of both proteases characterized by a lysosomal localization of cathepsin L and a nuclear localization of cathepsin V. These intracellular localization patterns of both enzymes were also observed in normal keratinocytes of human skin. In accordance to the differences in substrate specificity and pH stability, these results suggest different functions of cathepsin L and cathepsin V in human skin during the process of regeneration from excisional wounding
Synthesis, characterization and applications of metal and metal oxide nanoparticles
No full textAn extensive literature survey of synthetic methods of metal and metal oxide nanoparticles has been done and presented in Chapter 1. This Chapter begins with a few definitions, a note on stabilization processes and reducing agents. Then it extends to various methods for the synthesis of metal and metal oxide nanoparticles and ends with a Table, which provides important applications of various nanoparticles, found in the literature. The primary objective of this work was to synthesize metal nanoclusters using polyoxometalate as stabilizers by 'bottom up' chemical synthesis. In Chapter 2-5, the synthesis, characterization and applications of polyoxometalate stabilized noble metal nanoclusters have been given. The catalytic life span shown by Pd nanoclusters in hydrogenation reactions is remarkable and deserves further exploration. The advantage of the present method of synthesis is due to its ease compared to literature reported protocols. Chapter er 6-7, describes novel routes to prepare high surface area zirconia as well as implantation of pre-prepared Pd and Pt nanoclusters on its matrix to obtain heterogeneous catalysts. These catalysts have been examined for hydrogenation reactions and were found to be better catalysts in terms of Turnover frequency than literature reported catalysts, which can be applied to industrial applications. Chapter 8, describes application of dynamic light scattering (DLS) and UV-visible spectroscopy in following kinetics of nanoparticles formation. Finally, application of DLS in measuring particles of size ranging from 1-200 nm in diameter has been demonstrated
Exponentialabbildungen mit entkommendem singulären Orbit
No full textWe show combinatorial rigidity for escaping maps within the exponential family {exp(z)+kappa: kappa in C}: every pair of external address s=(s_n) and speed of escape t is realized by the escaping singular orbit of exactly one map exp(z)+kappa, defining continuous so-called parameter rays G(s)(t):=kappa. Two independent proofs are presented: a bare-hands approach and a variant of the spider algorithm as an intuitive version of infinite-dimensional Teichmüller theory. We show that the path-connected components of the set of parameters with escaping singular orbit are exactly the parameter rays.Wir zeigen Starrheit der Kombinatorik für Exponentialabbildungen innerhalb der Exponentialfamilie {exp(z)+kappa: kappa in C}: Jedes Paar von einer externen Adresse s=(s_n) und Entkommensgeschwindigkeit t wird realisiert durch den singulären Orbit genau einer Abbildung exp(z)+kappa. Dieser Zusammenhang definiert stetige so genannte Parameterstrahlen G(s)(t):=kappa. Zwei unabhängige Beweise werden geführt: ein direkter Ansatz sowie eine Variante des Spinnenalgorithmus als intuitive Version unendlich-dimensionaler Teichmüllertheorie. Wir zeigen, dass die Wegzusammenhangskomponenten der Menge der Parameter mit entkommendem singulären Orbit genau die Parameterstrahlen sind
Forum-based online knowledge communities : knowledge processes and their factors of influence : an empirical study using structural equation modeling
No full textKnowledge is becoming ever more important as an individual good, and as a social and economic resource. The research interest of this thesis is how knowledge processes can be optimally supported in the cooperative context of forum-based Online Knowledge Communities (OKCs). The research focuses especially on the two key processes knowledge creation and knowledge transfer. The starting point of the research is a literature review and the outline of individual hypotheses on the basis of an interdisciplinary body of research from the fields of computer science and management science, specifically knowledge management literature, community of practice literature, human-computer interaction literature, and collaborative systems literature. Following the literature review, the empirical part of the research is based on an in-depth study of the users of the electronic communication forums at International University Bremen (IUB). Both empirical parts of research - an ANOVA-based calculation of type of content-based knowledge process values and a SEM-based hypotheses testing of individual factors of impact on an individual's knowledge process contribution - could be shown to be in line with the theoretically deduced hypotheses. Besides the careful selection of a forum-platform (factor service quality) and carefully drafting of the initial content in the case of newly established online knowledge communities (factor perceived quality of content), the best strategy to stimulate participants to contribute a larger share of knowledge-process-relevant content appears to be the emphasis of the online forum as an online knowledge community, with a focus on professional as opposed to social content (factors social vs. professional affiliation motivation). The thesis integrates existing, fragmented research with a limited focus on a restricted number of input aspects and/or knowledge processes into an integrated model of forum-based collaborative knowledge management
Downstream Processing of Natural Products: Carminic Acid
No full textCarminic acid (E 120) is a natural colorant extracted from cochineal e.g., the desiccated bodies of Dactylopius coccus Costa female insects. The major usage of Natural Red lies in the food, cosmetic and pharmaceutical industries. The recovery and purification of carminic acid from raw cochineal is regarded as a difficult and complicated process. Current industrial technology suffers from low and irreproducible yields while generating a low quality final product. An improved strategy for the downstream processing of carminic acid was developed. Beaded adsorbents were screened and subsequently tested in packed-bed and finite bath contactors. Efficient adsorption and desorption conditions were found for two resin types. Different mass transfer resistance mechanisms were identified. Fluid side effects and intraparticle resistance mechanisms were dominating. This was quantitatively described in terms of film mass transport coefficients and particle diffusivities. Employing batch adsorption in an agitated vessel in combination with a macroporous beaded adsorbent showed a dramatic increase in sorption performance as a function of the fluid regime in the vessel. A hybrid mechanism including a perfusion like component can be hypothesized in order to explain these experimental findings. Quantitative evaluation of these events required the definition of a modified pore mass transfer coefficient or hyperdiffusivity, which is able to account the influence of mixing on sorption kinetics. The knowledge generated served as the basis for the design of an adsorption process at the pilot scale. The process yielded a high quality carminic acid preparation. The final product complied with food industry regulations and it was free of toxic metal ions and allergenic components. Process productivities compared favorably with current manufacturing schemes. General criteria for further scale-up are provided
Spatial Network Growth
No full textAlmost all real-world networks are distributed in space. In many of these networks, more short- than long-distance connections exist. Thus, there is a preference to minimize the length of connections. Such networks often exhibit properties of small-world, scale-free or multi-clustered networks. However, previous models for development, where only distance between nodes is considered when establishing a connection, were unable to yield spatial graphs with these properties.
I present a new model for spatial graph development that can generate small-world networks. Notably, also scale-free networks (similar to the German highway system or the yeast protein-protein interaction network) can be generated without using preferential attachment. The final topology of the network depended on whether the growing network reached spatial limits during development or not. Furthermore, different models for network evolution (limited, unlimited and preferential attachment) could be distinguished by observing the change of density and clustering coefficient over time.
Spatial growth was able to yield networks similar to real-world spatial networks. As a case study, I generated networks similar to cortical networks. I found that not only global network properties but also wiring properties were similar. In addition, multiple clusters could be generated by introducing time windows
Explicit 8-descent on elliptic curves
No full textIn this thesis I describe an explicit method for performing an 8-descent on an elliptic curve E over the rational numbers. An 8-descent is the next step after a 2- and a 4-descent. The method of 2-descent belongs to the classical tools in arithmetic geometry. More recent is the exploration of higher 2-descent. In 1996 Merriman, Siksek, and Smart found a method for doing 4-descent, and a different method for 4-descent was presented in 1998 by Cassels. I have been working on extending these methods to an 8-descent. I present a method for computing the 8-Selmer group of E as an abstract group, and next, for representing its elements as 8-coverings of E. With this method I was able to compute some examples, one of which is a curve of order 8 in the Shafarevich-Tate group of an elliptic curve. This is the first explicit example of a curve of such high order in Sha