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Despite intensive research over the last three decades, it has not yet been possible to bring an effective vaccine against human immunodeficiency virus (HIV) and the resulting acquired immunodeficiency syndrome (AIDS) to market. Virus-like particles (VLP) are a promising approach for efficient and effective vaccination and could play an important role in the fight against HIV. For example, HEK293 (human embryo kidney) cells can be used to produce virus-like particles. In this context, given the quality-by-design (QbD) concept for manufacturing, a digital twin is of great importance for the production of HIV-Gag-formed VLPs. In this work, a dynamic metabolic model for the production of HIV-Gag VLPs was developed and validated. The model can represent the VLP production as well as the consumption or formation of all important substrates and metabolites. Thus, in combination with already described process analytical technology (PAT) methods, the final step towards the implementation of a digital twin for process development and design, as well as process automation, was completed.
This paper documents the design, implementation and evaluation of the Unfolding Space Glove—an open source sensory substitution device. It transmits the relative position and distance of nearby objects as vibratory stimuli to the back of the hand and thus enables blind people to haptically explore the depth of their surrounding space, assisting with navigation tasks such as object recognition and wayfinding. The prototype requires no external hardware, is highly portable, operates in all lighting conditions, and provides continuous and immediate feedback—all while being visually unobtrusive. Both blind (n = 8) and blindfolded sighted participants (n = 6) completed structured training and obstacle courses with both the prototype and a white long cane to allow performance comparisons to be drawn between them. The subjects quickly learned how to use the glove and successfully completed all of the trials, though still being slower with it than with the cane. Qualitative interviews revealed a high level of usability and user experience. Overall, the results indicate the general processability of spatial information through sensory substitution using haptic, vibrotactile interfaces. Further research would be required to evaluate the prototype’s capabilities after extensive training and to derive a fully functional navigation aid from its features.
This study aimed to simulate the sector-coupled energy system of Germany in 2030 with the restriction on CO2 emission levels and to observe how the system evolves with decreasing emissions. Moreover, the study presented an analysis of the interconnection between electricity, heat and hydrogen and how technologies providing flexibility will react when restricting CO2 emissions levels. This investigation has not yet been carried out with the technologies under consideration in this study. It shows how the energy system behaves under different set boundaries of CO2 emissions and how the costs and technologies change with different emission levels. The study results show that the installed capacities of renewable technologies constantly increase with higher limitations on emissions. However, their usage rates decreases with low CO2 emission levels in response to higher curtailed energy. The sector-coupled technologies behave differently in this regard. Heat pumps show similar behaviour, while the electrolysers usage rate increases with more renewable energy penetration. The system flexibility is not primarily driven by the hydrogen sector, but in low CO2 emission level scenarios, the flexibility shifts towards the heating sector and electrical batteries.
In this work, supported cellulose acetate (CA) mixed matrix membranes (MMMs) were prepared and studied concerning their gas separation behaviors. The dispersion of carbon nanotube fillers were studied as a factor of polymer and filler concentrations using the mixing methods of the rotor–stator system (RS) and the three-roll-mill system (TRM). Compared to the dispersion quality achieved by RS, samples prepared using the TRM seem to have slightly bigger, but fewer and more homogenously distributed, agglomerates. The green γ-butyrolactone (GBL) was chosen as a polyimide (PI) polymer-solvent, whereas diacetone alcohol (DAA) was used for preparing the CA solutions. The coating of the thin CA separation layer was applied using a spin coater. For coating on the PP carriers, a short parameter study was conducted regarding the plasma treatment to affect the wettability, the coating speed, and the volume of dispersion that was applied to the carrier. As predicted by the parameter study, the amount of dispersion that remained on the carriers decreased with an increasing rotational speed during the spin coating process. The dry separation layer thickness was varied between about 1.4 and 4.7 μm. Electrically conductive additives in a non-conductive matrix showed a steeply increasing electrical conductivity after passing the so-called percolation threshold. This was used to evaluate the agglomeration behavior in suspension and in the applied layer. Gas permeation tests were performed using a constant volume apparatus at feed pressures of 5, 10, and 15 bar. The highest calculated CO2/N2 selectivity (ideal), 21, was achieved for the CA membrane and corresponded to a CO2 permeability of 49.6 Barrer.
In water electrolyzers, polymer electrolyte membranes (PEMs) such as Nafion can accumulate cations stemming from salt impurities in the water supply, which leads to severe cell voltage increases. This combined experimental and computational study discusses the influence of sodium ion poisoning on the ionic conductivity of Nafion membranes and the ion transport in a thereon based water electrolysis cell. Conductivities of Nafion and aqueous solutions with the same amount of dissolved cations are measured with impedance spectroscopy and compared with respect to Nafion’s microstructure. The dynamic behavior of the voltage of a water electrolysis cell is characterized as a function of the sodium ion content and current density, showing the differences of the ion transport at alternating and direct currents. These experimental results are elucidated with a physical ion transport model for sodium ion poisoned Nafion membranes, which describes a proton depletion and sodium ion accumulation at the cathode. During proton depletion, the cathodic hydrogen evolution is maintained by the water reduction that forms hydroxide ions. Together with sodium ions from the membrane, the formed hydroxide ions can diffuse pairwise into the water supply, so that the membrane’s sodium ions can be at least partly be replaced with anodically formed protons.
Abstract
(−)‐Menthol is one of the most popular aroma compounds worldwide. While in the past mostly extracted from mint plants, today (−)‐menthol synthesis from other raw materials is becoming more relevant. Common starting materials for menthol synthesis are m‐cresol, citral and myrcene, but also substrates like menthone, mono‐ and bicyclic terpenes and terpenoids have been used for this purpose in the past. As for many applications (−)‐menthol of high purity is required, asymmetric syntheses and enantiomeric resolution of obtained raw products are applied for menthol production. This review gives an overview on the most important synthetic menthol production processes of the companies Symrise, Takasago and BASF and relevant literature in the field of menthol synthesis with a focus on the last 20 years.
Die Dimensionierung von thermischen Speichern in der Gebäudetechnik bezieht sich häufig auf die Trinkwassererwärmung mit der DIN 4708. Dabei werden in der Regel die Bedarfe der Nutzer zur Auslegung herangezogen. Bekannt ist das Summenlinienverfahren und der daraus resultierende Beitrag des Wärmeerzeugers. Bei Pufferspeichern wird dagegen unter-schieden in welcher Kombination von Speicher und Wärmerzeuger dieser eingesetzt werden soll und es kommt häufig zu Größenschätzungen und Auslegungen mit Richtwerten. Daneben bieten zahlreiche Herstellern Auslegungsprogramme, die immer auf den Spitzenbedarf des Gebäudes ausgelegt sind.
In diesem Beitrag wird eine Methode vorgestellt, die den thermischen Speicher als zweiten Wärmeversorger im Gebäude betrachtet, der zusammen mit diesem die Versorgung über-nimmt. Damit wird die Speicherauslegung mit der Wärmeerzeugerleistung verknüpft. Aus-gleichend über eine bestimmte Zeitperiode (24 h) mit Phasen hohen und niedrigen Bedarfs übernehmen der Wärmeerzeuger und der Speicher gemeinsam die Versorgung. Da die Wärmeversorgung eines Gebäudes in erster Linie von der Außenlufttemperatur abhängt, wird hier ein Verfahren auf dieser Basis vorgestellt, welches eine einfache Berechnung des Wärmeinhalts eines Speichers ermöglicht.
The oxidation of cumene and following cleavage of cumene hydroperoxide (CHP) with sulfuric acid (Hock rearrangement) is still, by far, the dominant synthetic route to produce phenol. In 2020, the global phenol market reached a value of 23.3 billion US$ with a projected compound annual growth rate of 3.4% for 2020–2025. From ecological and economical viewpoints, the key step of this process is the cleavage of CHP. One sought-after way to likewise reduce energy consumption and waste production of the process is to substitute sulfuric acid with heterogeneous catalysts. Different types of zeolites, silicon-based clays, heteropoly acids, and ion exchange resins have been investigated and tested in various studies. For every type of these solid acid catalysts, several materials were found that show high yield and selectivity to phenol. In this mini-review, first a brief introduction and overview on the Hock process is given. Next, the mechanism, kinetics, and safety aspects are summarized and discussed. Following, the different types of heterogeneous catalysts and their performance as catalyst in the Hock process are illustrated. Finally, the different approaches to substitute sulfuric acid in the synthetic route to produce phenol are briefly concluded and a short outlook is given.
New risk geographies are emerging with war and conflict resurfacing, including nuclear threats. This poses challenges to civil protection for conducting risk-informed preparedness planning. A spatial assessment of Germany and Europe is conducted using a geographic information system. Buffer circles of nuclear explosion effects and fallout buffers show potentially exposed areas around major cities. Different scenarios indicate shrinking areas safe from exposure. However, even in a densely populated country, rural areas and smaller cities can be identified that could provide sites for evacuation shelters. Changing wind directions poses a challenge for civil protection planning because fallout risk covers most German territory even when few cities are attacked. However, wind speeds and topography can help identify suitable shelter areas. More knowledge about the temporal development of a nuclear explosion and its specific forms of harm can also help to improve risk knowledge and planning. While nuclear warfare at first seems to render useless any option for safe areas and survival, the spatial risk assessment shows that exposure does not occur at all places at all times. Being safe from harm will be difficult in such a worst-case scenario, but avoiding large city perimeters and being informed can also help reduce risk.
Pressure injuries remain a serious health complication for patients and nursing staff. Evidence from the past decade has not been analysed through narrative synthesis yet. PubMed, Embase, CINAHL Complete, Web of Science, Cochrane Library, and other reviews/sources were screened. Risk of bias was evaluated using a slightly modified QUIPS tool. Risk factor domains were used to assign (non)statistically independent risk factors. Hence, 67 studies with 679,660 patients were included. In low to moderate risk of bias studies, non-blanchable erythema reliably predicted pressure injury stage 2. Factors influencing mechanical boundary conditions, e.g., higher interface pressure or BMI < 18.5, as well as factors affecting interindividual susceptibility (male sex, older age, anemia, hypoalbuminemia, diabetes, hypotension, low physical activity, existing pressure injuries) and treatment-related aspects, such as length of stay in intensive care units, were identified as possible risk factors for pressure injury development. Health care professionals’ evidence-based knowledge of above-mentioned risk factors is vital to ensure optimal prevention and/or treatment. Openly accessible risk factors, e.g., sex, age, BMI, pre-existing diabetes, and non-blanchable erythema, can serve as yellow flags for pressure injury development. Close communication concerning further risk factors, e.g., anemia, hypoalbuminemia, or low physical activity, may optimize prevention and/or treatment. Further high-quality evidence is warranted.