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Many important properties of bacterial cellulose (BC), such as moisture absorption capacity, elasticity and tensile strength, largely depend on its structure. This paper presents a study on the effect of the drying method on BC films produced by Medusomyces gisevii using two different procedures: room temperature drying (RT, (24 ± 2 °C, humidity 65 ± 1%, dried until a constant weight was reached) and freeze-drying (FD, treated at − 75 °C for 48 h). BC was synthesized using one of two different carbon sources—either glucose or sucrose. Structural differences in the obtained BC films were evaluated using atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray diffraction. Macroscopically, the RT samples appeared semi-transparent and smooth, whereas the FD group exhibited an opaque white color and sponge-like structure. SEM examination showed denser packing of fibrils in FD samples while RT-samples displayed smaller average fiber diameter, lower surface roughness and less porosity. AFM confirmed the SEM observations and showed that the FD material exhibited a more branched structure and a higher surface roughness. The samples cultivated in a glucose-containing nutrient medium, generally displayed a straight and ordered shape of fibrils compared to the sucrose-derived BC, characterized by a rougher and wavier structure. The BC films dried under different conditions showed distinctly different crystallinity degrees, whereas the carbon source in the culture medium was found to have a relatively small effect on the BC crystallinity.
To gain insight on chemical sterilization processes, the influence of temperature (up to 70 °C), intense green light, and hydrogen peroxide (H₂O₂) concentration (up to 30% in aqueous solution) on microbial spore inactivation is evaluated by in-situ Raman spectroscopy with an optical trap. Bacillus atrophaeus is utilized as a model organism. Individual spores are isolated and their chemical makeup is monitored under dynamically changing conditions (temperature, light, and H₂O₂ concentration) to mimic industrially relevant process parameters for sterilization in the field of aseptic food processing. While isolated spores in water are highly stable, even at elevated temperatures of 70 °C, exposure to H₂O₂ leads to a loss of spore integrity characterized by the release of the key spore biomarker dipicolinic acid (DPA) in a concentration-dependent manner, which indicates damage to the inner membrane of the spore. Intensive light or heat, both of which accelerate the decomposition of H₂O₂ into reactive oxygen species (ROS), drastically shorten the spore lifetime, suggesting the formation of ROS as a rate-limiting step during sterilization. It is concluded that Raman spectroscopy can deliver mechanistic insight into the mode of action of H₂O₂-based sterilization and reveal the individual contributions of different sterilization methods acting in tandem.
Das Projekt "ARRK Journeys" entwickelt ein neues Dokumentarfilm-Format, das darauf abzielt, potenzielle Mitarbeiter für die ARRK Engineering GmbH zu gewinnen
Das Ziel des Projekts ist es, die Vielfalt an Karrieremöglichkeiten bei der ARRK Engineering GmbH aufzuzeigen und die Attraktivität des Unternehmens als Arbeitgeber zu betonen. Durch individuelle Mitarbeitergeschichten werden die Fragen beantwortet, warum eine berufliche Laufbahn bei ARRK erstrebenswert ist, ob jeder die Möglichkeit hat, bei ARRK zu arbeiten, und welche Entwicklungsmöglichkeiten das Unternehmen bietet. "ARRK Journeys" betont das Wohlbefinden der Mitarbeiter und ihre persönliche Bindung zum Unternehmen, um eine positive Arbeitgebermarke zu schaffen.
"ARRK Journeys" präsentiert die ARRK Engineering GmbH als attraktiven Arbeitgeber und inspiriert potenzielle Mitarbeiter dazu, ihren eigenen Weg zu finden.
Weltweit sind 350 Millionen Menschen von Farbenfehlsichtigkeit betroffen, doch nur wenige wissen, dass es eine Lösung für genau dieses Problem gibt. Die ausgearbeitete Werbekampagne und neue Markenkommunikation für EnChroma soll genau diese Menschen ermutigen, sich mit ihrer Krankheit auseinanderzusetzen und das breite Konzept der Lösung zu verstehen. Die speziellen Brillen ermöglichen es den Menschen, Farben im Alltag und Berufsleben in echt wahrzunehmen und diese besser differenzieren zu können. Unsere Welt ist farbcodiert und deshalb ist es besonders wichtig, dass diese Menschen auf das Produkt aufmerksam gemacht werden.
Bringing brand experience to marketplaces : ein Online-Marktplatz, der Konsument und Marke verbindet
(2024)
«Keno» zeigt ein Konzept für einen Online-Marktplatz im Fashion-Segment, mit Fokus auf individueller Beratung, digitaler Anprobe und visueller sowie informativer Präsentation der Marken. Marktplätze werden aufgrund von großer Auswahl und Vertrauenswürdigkeit von Konsument:innen bevorzugt aufgesucht. Durch die immersive Darstellung an einem maßgetreuen Avatar und die Einbindung der Marke in das Einkaufserlebnis soll hier die Zahl der Retouren verringert und die Kund:innenzufriedenheit gesteigert werden. Mittels nutzerorientierter Strategien und der Gestaltung eines Designsystems bekam «Keno» seinen Look. Dabei fanden modernste Techniken wie künstliche Intelligenzen und Design Token Systeme Verwendung. Das Projekt zeigt letztendlich Möglichkeiten auf, wie ein Marktplatz durch Brand Experience, Onlineshopping-Wege verkürzen und zu mehr Nachhaltigkeit im E-Commerce beitragen kann.
Drought and water shortage are serious problems in many arid and semi-arid regions. This problem is getting worse and even continues in temperate climatic regions due to climate change. To address this problem, the use of biodegradable hydrogels is increasingly important for the application as water-retaining additives in soil. Furthermore, efficient (micro-)nutrient supply can be provided by the use of tailored hydrogels. Biodegradable polyaspartic acid (PASP) hydrogels with different available (1,6-hexamethylene diamine (HMD) and L-lysine (LYS)) and newly developed crosslinkers based on diesters of glycine (GLY) and (di-)ethylene glycol (DEG and EG, respectively) were synthesized and characterized using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) and regarding their swelling properties (kinetic, absorbency under load (AUL)) as well as biodegradability of PASP hydrogel. Copper (II) and zinc (II), respectively, were loaded as micronutrients in two different approaches: in situ with crosslinking and subsequent loading of prepared hydrogels. The results showed successful syntheses of di-glycine-ester-based crosslinkers. Hydrogels with good water-absorbing properties were formed. Moreover, the developed crosslinking agents in combination with the specific reaction conditions resulted in higher water absorbency with increased crosslinker content used in synthesis (10% vs. 20%). The prepared hydrogels are candidates for water-storing soil additives due to the biodegradability of PASP, which is shown in an exemple. The incorporation of Cu(II) and Zn(II) ions can provide these micronutrients for plant growth.
The “1. Stokes’ problem”, the “suddenly accelerated flat wall”, is the oldest application of the Navier-Stokes equations. Stokes’ solution of the “problem” does not comply with the mathematical theorem of Cauchy and Kowalewskaya on the “Uniqueness and Existence” of solutions of partial differential equations and violates the physical theorem of minimum entropy production/dissipation of the Thermodynamics of Irreversible Processes. The result includes very high local shear stresses and dissipation rates. That is of special interest for the theory of turbulent and mixed turbulent/laminar flow. A textbook solution of the “1. Stokes Problem” is the Couette flow, which has a constant sheer stress along a linear profile. A consequence is that the Navier-Stokes equations do not describe any S-shaped part of a turbulent profile found in any turbulent Couette experiment. The paper surveys arguments referring to that statement, concerning the history of >150 years. Contrary to this there is always a Navier-Stokes solution near the wall, observed by a linear part of the Couette profile. There a turbulent description (e.g. by the logarithmic law-of-the-wall) fails completely. That is explained by the minimum dissipation requirement together with the Couette feature τ = const. The local co-existence of a turbulent zone and a laminar zone near the wall is stable and observed also at high Reynolds-Numbers.
Positionssensorvorrichtung
(2024)
Die Erfindung betrifft eine Positionssensorvorrichtung zur Bestimmung einer Absolutposition eines beweglichen ersten Teils relativ zu einem ortsfesten zweiten Teil mit einem mit dem beweglichen ersten Teil gekoppelter Codekörper, der dazu eingerichtet ist, eine Codespur mit einer Mehrzahl von in Spurrichtung aufeinanderfolgenden Codeelementen zu enthalten zur Bildung eines Codewortes, mit einer magnetischen Detektionseinrichtung zur Detektion der Codespur, wobei die Detektionseinrichtung zum einen an dem Codekörper befestigte und entlang der Spurrichtung in einem solchen Abstand gegenpolig zueinander angeordnete Permanentmagneten aufweist, dass der Abstand mit einer vorgegebenen Länge der jeweiligen Codeelemente übereinstimmt, und zum anderen eine Anzahl von ortsfest und quer zu dem Codekörper versetzt
angeordnete Wiegandsensoren aufweist, wobei der Abstand des Wiegandsensors zu einer Erstreckungsebene der Permanentmagneten derart gewählt ist, dass bei Überdeckung des Wiegandsensors durch den Permanentmagneten ein Wiegandpuls in dem Wiegandsensor induziert wird.
The deformation and damage laws of non-homogeneous irregular structural planes in rocks are the basis for studying the stability of rock engineering. To investigate the damage characteristics of rock containing non-parallel fissures, uniaxial compression tests and numerical simulations were conducted on sandstone specimens containing three non-parallel fissures inclined at 0°, 45° and 90° in this study. The characteristics of crack initiation and crack evolution of fissures with different inclinations were analyzed. A constitutive model for the discontinuous fractures of fissured sandstone was proposed. The results show that the fracture behaviors of fissured sandstone specimens are discontinuous. The stress–strain curves are non-smooth and can be divided into nonlinear crack closure stage, linear elastic stage, plastic stage and brittle failure stage, of which the plastic stage contains discontinuous stress drops. During the uniaxial compression test, the middle or ends of 0° fissures were the first to crack compared to 45° and 90° fissures. The end with small distance between 0° and 45° fissures cracked first, and the end with large distance cracked later. After the final failure, 0° fissures in all specimens were fractured, while 45° and 90° fissures were not necessarily fractured. Numerical simulation results show that the concentration of compressive stress at the tips of 0°, 45° and 90° fissures, as well as the concentration of tensile stress on both sides, decreased with the increase of the inclination angle. A constitutive model for the discontinuous fractures of fissured sandstone specimens was derived by combining the logistic model and damage mechanic theory. This model can well describe the discontinuous drops of stress and agrees well with the whole processes of the stress–strain curves of the fissured sandstone specimens.