Refine
H-BRS Bibliography
- yes (10)
Departments, institutes and facilities
Document Type
- Article (7)
- Conference Object (2)
- Working Paper (1)
Keywords
- chemometrics (2)
- classification (2)
- discriminant analysis (2)
- food-related bacteria (2)
- lignin (2)
- stress response (2)
- Antioxidant activity (1)
- Aufgabenkritik (1)
- Biomass (1)
- Chemometrics (1)
Because the robust and rapid determination of spoilage microorganisms is becoming increasingly important in industry, the use of IR microspectroscopy, and the establishment of robust and versatile chemometric models for data processing and classification, is gaining importance. To further improve the chemometric models, bacterial stress responses were induced, to study the effect on the IR spectra and to improve the chemometric model. Thus, in this work, nine important food-relevant microorganisms were subjected to eight stress conditions, besides the regular culturing as a reference. Spectral changes compared to normal growth conditions without stressors were found in the spectral regions of 900–1500 cm−1 and 1500–1700 cm−1. These differences might stem from changes in the protein secondary structure, exopolymer production, and concentration of nucleic acids, lipids, and polysaccharides. As a result, a model for the discrimination of the studied microorganisms at the genus, species and strain level was established, with an accuracy of 96.6%. This was achieved despite the inclusion of various stress conditions and times after incubation of the bacteria. In addition, a model was developed for each individual microorganism, to separate each stress condition or regular treatment with 100% accuracy.
Discrimination of Stressed and Non-Stressed Food-Related Bacteria Using Raman-Microspectroscopy
(2022)
As the identification of microorganisms becomes more significant in industry, so does the utilization of microspectroscopy and the development of effective chemometric models for data analysis and classification. Since only microorganisms cultivated under laboratory conditions can be identified, but they are exposed to a variety of stress factors, such as temperature differences, there is a demand for a method that can take these stress factors and the associated reactions of the bacteria into account. Therefore, bacterial stress reactions to lifetime conditions (regular treatment, 25 °C, HCl, 2-propanol, NaOH) and sampling conditions (cold sampling, desiccation, heat drying) were induced to explore the effects on Raman spectra in order to improve the chemometric models. As a result, in this study nine food-relevant bacteria were exposed to seven stress conditions in addition to routine cultivation as a control. Spectral alterations in lipids, polysaccharides, nucleic acids, and proteins were observed when compared to normal growth circumstances without stresses. Regardless of the involvement of several stress factors and storage times, a model for differentiating the analyzed microorganisms from genus down to strain level was developed. Classification of the independent training dataset at genus and species level for Escherichia coli and at strain level for the other food relevant microorganisms showed a classification rate of 97.6%.
Polyurethane (PU) coatings were successfully produced using unmodified kraft lignin (KL) as an environmentally benign component in contents of up to 80 wt%. Lignin samples were precipitated from industrial black liquor in aqueous solution working at room temperature and different pH levels (pH 2 to pH 5). Lignins were characterized by UV-Vis, FTIR, pyrolysis-GC/MS, SEC and 31P-NMR. Results show a correlation between pH level, OH number and molecular weight Mw of isolated lignins. Lignin-based polyurethane coatings were prepared in an efficient one step synthesis dissolving lignin in THF and PEG425 in an ultrasonic bath followed by addition of 4,4-diphenylmethanediisocyanate (MDI) and triethylamine (TEA). Crosslinking was achieved under very mild conditions (1 hour at room temperature followed by 3 hours at 35 °C). The resulting coatings were characterized regarding their physical properties including ATR-IR, TGA, optical contact angle, light microscopy, REM-EDX and AFM data. Transparent homogeneous films of high flexibility resulted from lignins isolated at pH 4, possessing a temperature resistance up to 160 °C. Swelling tests revealed a resistance against water. Swelling in DMSO depends on index, pH of precipitation and catalyst utilization for PU preparation. According to AFM studies, surface roughness is between 10 and 28 nm.
Due to global ecological and economic challenges that have been correlated to the transition from fossil-based to renewable resources, fundamental studies are being performed worldwide to replace fossil fuel raw materials in plastic production. One aspect of current research is the development of lignin-derived polyols to substitute expensive fossil-based polyol components for polyurethane and polyester production. This article describes the synthesis of bioactive lignin-based polyurethane coatings using unmodified and demethylated Kraft lignins. Demethylation was performed to enhance the reaction selectivity toward polyurethane formation. The antimicrobial activity was tested according to a slightly modified standard test (JIS Z 2801:2010). Besides effects caused by the lignins themselves, triphenylmethane derivatives (brilliant green and crystal violet) were used as additional antimicrobial substances. Results showed increased antimicrobial capacity against Staphylococcus aureus. Furthermore, the coating color could be varied from dark brown to green and blue, respectively.
Lignocellulose feedstock (LCF) provides a sustainable source of components to produce bioenergy, biofuel, and novel biomaterials. Besides hard and soft wood, so-called low-input plants such as Miscanthus are interesting crops to be investigated as potential feedstock for the second generation biorefinery. The status quo regarding the availability and composition of different plants, including grasses and fast-growing trees (i.e., Miscanthus, Paulownia), is reviewed here. The second focus of this review is the potential of multivariate data processing to be used for biomass analysis and quality control. Experimental data obtained by spectroscopic methods, such as nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR), can be processed using computational techniques to characterize the 3D structure and energetic properties of the feedstock building blocks, including complex linkages. Here, we provide a brief summary of recently reported experimental data for structural analysis of LCF biomasses, and give our perspectives on the role of chemometrics in understanding and elucidating on LCF composition and lignin 3D structure.
Der Öffentliche Gesundheitsdienst (ÖGD) übernimmt eine wichtige Funktion in Sachen Bevölkerungsgesundheit und wird häufig, neben ambulanter und stationärer Versorgung, als ‚dritte Säule‘ im deutschen Gesundheitswesen beschrieben. Diese sprachlich gleichwertige Positionierung spiegelt sich allerdings in der Realität nicht wider, im Vergleich ist seine Stellung eher schwach. In der Frage, welche Ursachen hierfür vorliegen, könnte eine Hypothese lauten, dass ein diffuses Aufgabenprofil einen negativen Einfluss auf seine Stellung ausübt. Um diesen möglichen Einfluss näher zu untersuchen, lautet die Forschungsfrage: „Wie lässt sich die Stellung des ÖGD innerhalb des deutschen Gesundheitswesens anhand seines Aufgabenprofils aus kontingenztheoretischer Perspektive erklären?“.
Zu deren Beantwortung wird zunächst die Ausgestaltung der aktuellen Aufgabenprofile erhoben und verglichen. Anschließend untersucht die Arbeit mit Hilfe der organisationssoziologischen Kontingenztheorie, welche situativen Einflussfaktoren sich möglicherweise auf Aufgabenprofil und damit auch die Stellung des ÖGD ausgewirkt haben. Im Ergebnis zeigt sich, dass Veränderungen in den Aufgaben teilweise recht deutlich in Verbindung gebracht werden können mit Veränderungen der Organisationssituation, auch lässt sich ein Zusammenhang zwischen Aufgabenprofil und Stellung vermuten. Soll dem ÖGD in Zukunft wieder eine stärkere Bedeutung zukommen, so ist es neben einer gewissen Vereinheitlichung der Aufgabenprofile von großer Bedeutung, ihm wieder exklusive Aufgaben zuzusprechen. Diese könnten insbesondere in den Bereichen Planung, Koordination und Steuerung, Datengewinnung und aufbereitung oder darin liegen, sich wieder verstärkt auf Bevölkerungsgruppen zu fokussieren, welche nicht durch andere Bereiche abgedeckt werden. Hierfür müssen die nötigen Ressourcen zur Verfügung stehen: Neben den bereits beschlossenen Unterstützungsleistungen gilt es insbesondere in Bezug auf die personelle Ausstattung, den ÖGD langfristig attraktiv zu gestalten. Dazu kann eine aufgewertete Stellung sowie eine verbesserte Situation in den einzelnen Behörden einen großen Teil beitragen.