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Due to the use of fossil fuel resources, many environmental problems have been increasingly growing. Thus, the recent research focuses on the use of environment friendly materials from sustainable feedstocks for future fuels, chemicals, fibers and polymers. Lignocellulosic biomass has become the raw material of choice for these new materials. Recently, the research has focused on using lignin as a substitute material in many industrial applications. The antiradical and antimicrobial activity of lignin and lignin-based films are both of great interest for applications such as food packaging additives. DPPH assay was used to determine the antioxidant activity of Kraft lignin compared to Organosolv lignins from different biomasses. The purification procedure of Kraft lignin showed that double-fold selective extraction is the most efficient confirmed by UV-Vis, FTIR, HSQC, 31PNMR, SEC, and XRD. The antioxidant capacity was discussed regarding the biomass source, pulping process, and degree of purification. Lignin obtained from industrial black liquor are compared with beech wood samples: Biomass source influences the DPPH inhibition (softwood > grass) and the TPC (softwood < grass). DPPH inhibition affected by the polarity of the extraction solvent. Following the trend: ethanol > diethylether > acetone. Reduced polydispersity has positive influence on the DPPH inhibition. Storage decreased the DPPH inhibition but increased the TPC values. The DPPH assay was also used to discuss the antiradical activity of HPMC/lignin and HPMC/lignin/chitosan films. In both binary (HPMC/lignin) and ternary (HPMC/lignin/chitosan) systems the 5% addition showed the highest activity and the highest addition had the lowest. Both scavenging activity and antimicrobial activity are dependent on the biomass source; Organosolv of softwood > Kraft of softwood > Organosolv of grass. Lignins and lignin-containing films showed high antimicrobial activities against Gram-positive and Gram-negative bacteria at 35 °C and at low temperatures (0-7 °C). Purification of Kraft lignin has a negative effect on the antimicrobial activity while storage has positive effect. The lignin leaching in the produced films affected the activity positively and the chitosan addition enhances the activity for both Gram-positive and Gram-negative bacteria. Testing the films against food spoilage bacteria that grow at low temperatures revealed the activity of the 30% addition on HPMC/L1 film against both B. thermosphacta and P. fluorescens while L5 was active only against B. thermosphacta. In HPMC/lignin/chitosan films, the 5% addition exhibited activity against both food spoilage bacteria.
The actomyosin system generates mechanical work with the execution of the power stroke, an ATP-driven, two-step rotational swing of the myosin-neck that occurs post ATP hydrolysis during the transition from weakly to strongly actin-bound myosin states concomitant with Pi release and prior to ADP dissociation. The activating role of actin on product release and force generation is well documented; however, the communication paths associated with weak-to-strong transitions are poorly characterized. With the aid of mutant analyses based on kinetic investigations and simulations, we identified the W-helix as an important hub coupling the structural changes of switch elements during ATP hydrolysis to temporally controlled interactions with actin that are passed to the central transducer and converter. Disturbing the W-helix/transducer pathway increased actin-activated ATP turnover and reduced motor performance as a consequence of prolonged duration of the strongly actin-attached states. Actin-triggered Pi release was accelerated, while ADP release considerably decelerated, both limiting maximum ATPase, thus transforming myosin-2 into a high-duty-ratio motor. This kinetic signature of the mutant allowed us to define the fractional occupancies of intermediate states during the ATPase cycle providing evidence that myosin populates a cleft-closure state of strong actin interaction during the weak-to-strong transition with bound hydrolysis products before accomplishing the power stroke.
Bedingt durch die zunehmende Rohstoffknappheit rückt die Suche nach alternativen, nachhaltigen Rohstoffen immer mehr in den Vordergrund. Im Hinblick auf effiziente chemische Verwertbarkeit bietet Lignin zahlreiche Vorteile für verschiedene Anwendungsbereiche, beispielsweise für biobasierte Polyurethanbeschichtungen, etwa zum Korrosionsschutz. Wesentliche Probleme bei der Verwendung von Lignin ergeben sich durch die Heterogenität dieses Naturstoffes sowie durch dessen geringe Polymerisations-Kompatibilität mit Polyolefinen; beide Faktoren beeinflussen u. a die mechanischen Eigenschaften entsprechender Lignin-basierter Polymere. Zudem hängt die konkrete Struktur und damit auch die physikalisch/chemischen Eigenschaften des Lignins stark von der jeweiligen Rohstoffquelle sowie dem Extraktionsverfahren ab.
Ziel dieser Arbeit war die Strukturaufklärung unmodifizierter und modifizierter Kraft-Lignine (KL) und die Untersuchung der Reaktivität aromatischer wie aliphatischer Hydroxygruppen in Abhängigkeit vom pH-Wert. Hierzu wurden unmodifizierte KL aus Schwarzlauge extrahiert und nachfolgend zunächst einer Soxhlet-Extraktion unterzogen, um in Methyltetrahydrofuran lösliche Lignin-Bestandteile – vornehmlich mit aromatischem Charakter – zu gewinnen und so eine verbesserte Löslichkeit auch im bei der nachfolgenden Polyurethansynthese als Lösemittel verwendeten THF zu gewährleisten. Überdies wurden die extrahierten KL via Demethylierung von Methoxygruppen chemisch modifiziert. Zudem wurde mittels nasschemischer Methoden sowie mit differentieller UV/VIS-Spektroskopie die Anzahl an für die Polymerisation erforderliche Hydroxygruppen quantifiziert. Im Anschluss erfolgte, unter besonderer Berücksichtigung ökologischer und ökonomischer Nachhaltigkeitsaspekte, die Synthese Lignin-basierter und funktionalisierter Polyurethanbeschichtungen. Die Oberflächenfunktionalisierung gestattete die Verbesserung der Oberflächenhomogenität sowie - via blend formation - das Einbetten von TPM-Farbstoffen in die Coatings. Hinsichtlich des Einflusses des bei der Extraktion gewählten pH-Wertes (pH = 2 - 5) auf das Verhalten der so gewonnenen KL wurde eine Veränderung sowohl der Struktur der Lignine als auch deren thermischer Stabilität beobachtet. Zudem wurde nachgewiesen, dass mit steigendem pH-Wert die Funktionalität/Reaktivität der aromatischen wie aliphatischen Hydroxygruppen im Lignin zunimmt. Aus unmodifiziertem KL wurden erfolgreich homogene Lignin-basierte Polyurethan-Coatings (LPU-Coatings) synthetisiert; diese LPU-Coatings zeigten bei Verwendung von bei höheren pH-Werten extrahierten KL homogenere, hydrophobe Oberflächenbeschaffenheit sowie gute thermische Stabilität. Zusätzliche Modifizierung der KL durch Demethylierung führte wegen der gesteigerten Anzahl freier Hydroxygruppen zu moderater Reaktivitätssteigerung und damit zu weiterer Verbesserung der Oberflächeneigenschaften hinsichtlich einer homogenen Oberflächenstruktur und -brillanz. Im Hinblick auf den Aspekt der Nachhaltigkeit wurden durch Syntheseoptimierung - bestehend aus Einstellung der Rohstoff-Korngröße, Ultraschallbehandlung und Verwendung des kommerziellen trifunktionellen Polyetherpolyols Lupranol® 3300 in Kombination mit Desmodur® L75 - die Löslichkeit von Lignin im Polyol sowie die thermische Stabilität der LPU-Coatings erhöht. Im Zuge der Syntheseoptimierungen konnte durch verkürzte Trocknungszeiten Energieeinsparung erzielt werden; zudem ließen sich dabei die eingesetzten Mengen kommerziell erhältlicher Chemikalien verringern; beide Einsparungen führten zu Kostenreduktion. Zugleich ließ sich so nicht nur der KL-Anteil im Polymer-Coating erhöhen: Durch eine optimierte wirtschaftliche Einstufensynthese ließ sich die Umsetzung dieser Vorgehensweise auch im Rahmen industrieller Anwendungen vereinfachen. Das Einbetten ausgewählter TPM-Farbstoffe (Kristallviolett und Brilliantgrün) in die LPU-Coatings durch blend formation führte nachweislich zu antimikrobieller Wirkung der Oberflächenbeschichtung, ohne dass die Oberflächenbeschaffenheit an Homogenität verlor. Die im Rahmen dieser Arbeit synthetisierten LPU-Coatings könnten zukünftig als Korrosionsschutz- und antimikrobielle-Beschichtungen ihre Anwendung finden, z. B. in der Landwirtschaft und im Bausektor.
Die im Rahmen der vorliegenden Arbeit gewonnen Erkenntnisse liefern einen Beitrag zur strukturellen Aufklärung des komplexen Biopolymers Lignin. Darüber hinaus stellen die Untersuchungen und Ergebnisse eine Grundlage für eine nachhaltige Herstellung von Lignin-basierten Polymerbeschichtungen dar, die in Zukunft immer mehr an Bedeutung gewinnen werden.
Among the celestial bodies in the Solar System, Mars currently represents the main target for the search for life beyond Earth. However, its surface is constantly exposed to high doses of cosmic rays (CRs) that may pose a threat to any biological system. For this reason, investigations into the limits of resistance of life to space relevant radiation is fundamental to speculate on the chance of finding extraterrestrial organisms on Mars. In the present work, as part of the STARLIFE project, the responses of dried colonies of the black fungus Cryomyces antarcticus Culture Collection of Fungi from Extreme Environments (CCFEE) 515 to the exposure to accelerated iron (LET: 200 keV/μm) ions, which mimic part of CRs spectrum, were investigated. Samples were exposed to the iron ions up to 1000 Gy in the presence of Martian regolith analogues. Our results showed an extraordinary resistance of the fungus in terms of survival, recovery of metabolic activity and DNA integrity. These experiments give new insights into the survival probability of possible terrestrial-like life forms on the present or past Martian surface and shallow subsurface environments.
The simultaneous operation of multiple different semiconducting metal oxide (MOX) gas sensors is demanding for the readout circuitry. The challenge results from the strongly varying signal intensities of the various sensor types to the target gas. While some sensors change their resistance only slightly, other types can react with a resistive change over a range of several decades. Therefore, a suitable readout circuit has to be able to capture all these resistive variations, requiring it to have a very large dynamic range. This work presents a compact embedded system that provides a full, high range input interface (readout and heater management) for MOX sensor operation. The system is modular and consists of a central mainboard that holds up to eight sensor-modules, each capable of supporting up to two MOX sensors, therefore supporting a total maximum of 16 different sensors. Its wide input range is archived using the resistance-to-time measurement method. The system is solely built with commercial off-the-shelf components and tested over a range spanning from 100Ω to 5 GΩ (9.7 decades) with an average measurement error of 0.27% and a maximum error of 2.11%. The heater management uses a well-tested power-circuit and supports multiple modes of operation, hence enabling the system to be used in highly automated measurement applications. The experimental part of this work presents the results of an exemplary screening of 16 sensors, which was performed to evaluate the system’s performance.
Extremophiles are optimal models in experimentally addressing questions about the effects of cosmic radiation on biological systems. The resistance to high charge energy (HZE) particles, and helium (He) ions and iron (Fe) ions (LET at 2.2 and 200 keV/µm, respectively, until 1000 Gy), of spores from two thermophiles, Bacillushorneckiae SBP3 and Bacilluslicheniformis T14, and two psychrotolerants, Bacillus sp. A34 and A43, was investigated. Spores survived He irradiation better, whereas they were more sensitive to Fe irradiation (until 500 Gy), with spores from thermophiles being more resistant to irradiations than psychrotolerants. The survived spores showed different germination kinetics, depending on the type/dose of irradiation and the germinant used. After exposure to He 1000 Gy, D-glucose increased the lag time of thermophilic spores and induced germination of psychrotolerants, whereas L-alanine and L-valine increased the germination efficiency, except alanine for A43. FTIR spectra showed important modifications to the structural components of spores after Fe irradiation at 250 Gy, which could explain the block in spore germination, whereas minor changes were observed after He radiation that could be related to the increased permeability of the inner membranes and alterations of receptor complex structures. Our results give new insights on HZE resistance of extremophiles that are useful in different contexts, including astrobiology.
Background: Coniferous woods (Abies nordmanniana (Stev.) Spach, Abies procera Rehd, Picea abies (L.) H.Karst, and Picea pungens Engelm.) could contain useful secondary metabolites to produce sustainable packaging materials, e.g., by substitution of harmful petrol-based additives in plastic packaging. This study aims to characterise the antioxidant and light-absorbing properties and ingredients of different coniferous wood extracts with regard to different plant fragments and drying conditions. Furthermore, the valorisation of used Christmas trees is evaluated. Methods: Different drying and extraction techniques were applied with the extracts being characterised by determining the total phenolic content (TPC), total antioxidant capacity (TAC), and absorbance in the ultraviolet range (UV). Gas chromatography coupled with mass spectrometry (GC-MS) and an acid–butanol assay (ABA) were used to characterise the extract constituents. Results: All the extracts show a considerably high UV absorbance while interspecies differences did occur. All the fresh and some of the dried biomass extracts reached utilisable TAC and TPC values. A simplified extraction setup for industrial application is evaluated; comparable TAC results could be reached with modifications. Conclusion: Coniferous woods are a promising renewable resource for preparation of sustainable antioxidants and photostabilisers. This particularly applies to Christmas trees used for up to 12 days. After extraction, the biomass can be fully valorised by incorporation in paper packaging.
Multiwalled carbon nanotubes (MWCNTs) were easily and efficiently functionalised with highly cross-linked polyamines. The radical polymerisation of two bis-vinylimidazolium salts in the presence of pristine MWCNTs and azobisisobutyronitrile (AIBN) as a radical initiator led to the formation of materials with a high functionalisation degree. The subsequent treatment with sodium borohydride gave rise to the reduction of imidazolium moieties with the concomitant formation of secondary and tertiary amino groups. The obtained materials were characterised by thermogravimetric analysis (TGA), elemental analysis, solid state 13C-NMR, Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), potentiometric titration, and temperature programmed desorption of carbon dioxide (CO2-TPD). One of the prepared materials was tested as a heterogeneous base catalyst in C–C bond forming reactions such as the Knoevenagel condensation and Henry reaction. Furthermore, two examples concerning a sequential one-pot approach involving two consecutive reactions, namely Knoevenagel and Michael reactions, were reported.
The motor protein myosin drives a wide range of cellular and muscular functions by generating directed movement and force, fueled through adenosine triphosphate (ATP) hydrolysis. Release of the hydrolysis product adenosine diphosphate (ADP) is a fundamental and regulatory process during force production. However, details about the molecular mechanism accompanying ADP release are scarce due to the lack of representative structures. Here we solved a novel blebbistatin-bound myosin conformation with critical structural elements in positions between the myosin pre-power stroke and rigor states. ADP in this structure is repositioned towards the surface by the phosphate-sensing P-loop, and stabilized in a partially unbound conformation via a salt-bridge between Arg131 and Glu187. A 5 Å rotation separates the mechanical converter in this conformation from the rigor position. The crystallized myosin structure thus resembles a conformation towards the end of the two-step power stroke, associated with ADP release. Computationally reconstructing ADP release from myosin by means of molecular dynamics simulations further supported the existence of an equivalent conformation along the power stroke that shows the same major characteristics in the myosin motor domain as the resolved blebbistatin-bound myosin-II·ADP crystal structure, and identified a communication hub centered on Arg232 that mediates chemomechanical energy transduction.
Current knowledge about cell-biomaterial interactions is often based on 2D cell culture systems like protein-coated glass slides. However, such smooth surfaces cannot mimic the nanofibrous environment of the native extracellular matrix (ECM). It is therefore a major challenge to transfer the results from 2D surfaces to 3D protein scaffolds with biomimetic nanofiber architecture. To understand the influence of different protein topographies on the cell response we introduce a new process to fabricate binary collagen scaffolds of variable thickness with spatially controlled regions of nanofibrous and smooth topography. We used pH-induced self-assembly to prepare collagen nanofibers with diameters between 130 and 150 nm on glass surfaces, which were partly covered with a polymer mask. After cross-linking with glutaraldehyde, smooth collagen films were prepared on the remaining glass regions. Atomic force microscopy revealed a much lower surface roughness of smooth collagen compared to nanofibers.
Toshiyuki Fukao
(2020)
Development and Validation of a Rapid and Reliable Method for TPMT Genotyping using real-time PCR
(2012)
Discrimination and classification of eight strains related to meat spoilage microorganisms commonly found in poultry meat were successfully carried out using two dispersive Raman spectrometers (Microscope and Portable Fiber-Optic systems) in combination with chemometric methods. Principal Components Analysis (PCA) and Multi-Class Support Vector Machines (MC-SVM) were applied to develop discrimination and classification models. These models were certified using validation data sets which were successfully assigned to the correct bacterial genera and even to the right strain. The discrimination of bacteria down to the strain level was performed for the pre-processed spectral data using a 3-stage model based on PCA. The spectral features and differences among the species on which the discrimination was based were clarified through PCA loadings. In MC-SVM the pre-processed spectral data was subjected to PCA and utilized to build a classification model. When using the first two components, the accuracy of the MC-SVM model was 97.64% and 93.23% for the validation data collected by the Raman Microscope and the Portable Fiber-Optic Raman system, respectively. The accuracy reached 100% for the validation data by using the first eight and ten PC’s from the data collected by Raman Microscope and by Portable Fiber-Optic Raman system, respectively. The results reflect the strong discriminative power and the high performance of the developed models, the suitability of the pre-processing method used in this study and that the low accuracy of the Portable Fiber-Optic Raman system does not adversely affect the discriminative power of the developed models.