Structure elucidation and toxicological evaluation of cyclic Polyethersulfone oligomers present in extracts of membrane filters. - In: Polymer engineering & science, ISSN 1548-2634, Bd. 62 (2022), 9, S. 2817-2825
Polyethersulfone (PES) is a widely used polymer in consumer and technical products. An important application is PES membranes used in the biopharmaceutical industry for sterilizing-grade filtration and for filtration of food and beverages. For both uses, detailed information about migrating compounds that can be extracted from the polymeric material into a liquid must be gathered. In the pharmaceutical industry, comprehensive extractables studies are required for contact materials, and the data is used in the qualification of the process equipment. PES is generated via polycondensation, which forms cyclic oligomers as a by-product of the reaction. However, no structural information is available for these cyclic oligomers so far. In this publication, we present the analytical determination of PES cyclic oligomers. Their presence in extracts of PES membrane filters is confirmed. The structure of the PES cyclic trimer is elucidated by X-ray and NMR investigation, obtained as crystals from the sublimation of the PES raw material. A strategy is shown to assess the toxicity of such cyclic oligomers and to derive a permitted daily exposure (PDE). The data will reduce the levels of unknowns in extractables and leachables screenings and supports the risk assessment of PES sterile filters.
https://doi.org/10.1002/pen.26064
Three soil bacterial communities from an archaeological excavation site of an ancient coal mine near Bennstedt (Germany) characterized by 16S r-RNA sequencing. - In: Environments, ISSN 2076-3298, Bd. 9 (2022), 9, 115, S. 1-19
This metagenomics investigation of three closely adjacent sampling sites from an archaeological excavation of a pre-industrial coal mining exploration shaft provides detailed information on the composition of the local soil bacterial communities. The observed significant differences between the samples, reflected in the 16S r-RNA analyses, were consistent with the archaeologically observed situation distinguishing the coal seam, the rapidly deposited bright sediment inside an exploration shaft, and the topsoil sediment. In general, the soils were characterized by a dominance of Proteobacteria, Actinobacteria, Acidobacteria, and Archaea, whereas the coal seam was characterized by the highest proportion of Proteobacteria; the topsoil was characterized by very high proportions of Archaea - in particular, Nitrosotaleaceae - and Acidobacteria, mainly of Subgroup 2. Interestingly, the samples of the fast-deposited bright sediment showed a rank function of OTU abundances with disproportional values in the lower abundance range. This could be interpreted as a reflection of the rapid redeposition of soil material during the refilling of the exploration shaft in the composition of the soil bacterial community. This interpretation is supported by the observation of a comparatively high proportion of reads relating to bacteria known to be alkaliphilic in this soil material. In summary, these investigations confirm that metagenomic analyses of soil material from archaeological excavations can provide valuable information about the local soil bacterial communities and the historical human impacts on them.
https://doi.org/10.3390/environments9090115
A new measurement method of contact conditions in a vacuum circuit breaker with the field emission current during the closing operation. - In: IEEE transactions on instrumentation and measurement, ISSN 0018-9456, Bd. 71 (2022), 6005111, insges. 11 S.
The performance of vacuum circuit breakers (VCBs) in the interruption and protection of an electric power system is highly dependent on the contact conditions; thus, the assessment of the contact conditions is essential. The field emission current has been recognized as an effective parameter with which to investigate the contact conditions both qualitatively and quantitatively. The traditional measurement method that uses the field emission current to determine the contact conditions is performed under ac voltage and requires the VCB to be dismantled, which limits the application of this method. The objective of this study is to develop a new measurement method for the contact conditions in a VCB with the field emission current during the closing operation under dc voltage. The new measurement method does not require the VCB to be dismantled and can simplify the processing of experimental data. Then, the new measurement method is applied to investigate the contact conditions during capacitive switching. The obtained result shows that the field enhancement factor $\beta $ of the contact surface oscillates up and down during the capacitive experiment, which can verify the conditioning and deconditioning effects of the inrush current on contact surfaces.
https://doi.org/10.1109/TIM.2022.3193710
Suppression of natural lens fluorescence in fundus autofluorescence measurements: review of hardware solutions. - In: Biomedical optics express, ISSN 2156-7085, Bd. 13 (2022), 10, S. 5151-5170
Fluorescence lifetime imaging ophthalmoscopy (FLIO), a technique for investigating metabolic changes in the eye ground, can reveal the first signs of diseases related to metabolism. The fluorescence of the natural lens overlies the fundus fluorescence. Although the influence of natural lens fluorescence can be somewhat decreased with mathematical models, excluding this influence during the measurement by using hardware enables more exact estimation of the fundus fluorescence. Here, we analyze four 1-photon excitation hardware solutions to suppress the influence of natural lens fluorescence: aperture stop separation, confocal scanning laser ophthalmoscopy, combined confocal scanning laser ophthalmoscopy and aperture stop separation, and dual point confocal scanning laser ophthalmoscopy. The effect of each principle is demonstrated in examples. The best suppression is provided by the dual point principle, realized with a confocal scanning laser ophthalmoscope. In this case, in addition to the fluorescence of the whole eye, the fluorescence of the anterior part of the eye is detected from a non-excited spot of the fundus. The intensity and time-resolved fluorescence spectral data of the fundus are derived through the subtraction of the simultaneously measured fluorescence of the excited and non-excited spots. Advantages of future 2-photon fluorescence excitation are also discussed. This study provides the first quantitative evaluation of hardware principles to suppress the fluorescence of the natural lens during measurements of fundus autofluorescence.
https://doi.org/10.1364/BOE.462559
Mathematical analysis of a low cost mechanical ventilator respiratory dynamics enhanced by a sensor transducer (ST) based in nanostructures of Anodic Aluminium Oxide (AAO). - In: Mathematics, ISSN 2227-7390, Bd. 10 (2022), 14, 2403, S. 1-32
Mechanical ventilation systems require a device for measuring the air flow provided to a patient in order to monitor and ensure the correct quantity of air proportionated to the patient, this device is the air flow sensor. At the beginning of the COVID-19 pandemic, flow sensors were not available in Peru because of the international supply shortage. In this context, a novel air flow sensor based on an orifice plate and an intelligent transducer was developed to form an integrated device. The proposed design was focused on simple manufacturing requirements for mass production in a developing country. CAD and CAE techniques were used in the design stage, and a mathematical model of the device was proposed and calibrated experimentally for the measured data transduction. The device was tested in its real working conditions and was therefore implemented in a breathing circuit connected to a low-cost mechanical ventilation system. Results indicate that the designed air flow sensor/transducer is a low-cost complete medical device for mechanical ventilators that is able to provide all the ventilation parameters by an equivalent electrical signal to directly display the following factors: air flow, pressure and volume over time. The evaluation of the designed sensor transducer was performed according to sundry transducer parameters such as geometrical parameters, material parameters and adaptive coefficients in the main transduction algorithm; in effect, the variety of the described results were achieved by the faster response time and robustness proportionated by transducers of nanostructures based on Anodic Aluminum Oxide (AAO), which enhanced the designed sensor/transducer (ST) during operation in intricate geographic places, such as the Andes mountains of Peru.
https://doi.org/10.3390/math10142403
Multifunctional water-organic hybrid electrolyte for rechargeable zinc ions batteries. - In: The chemical engineering journal, ISSN 1873-3212, Bd. 450 (2022), 3, 138265
Uncontrollable dendrite growth and parasitic reactions are the fundamental obstacles to achieve large-scale application of aqueous Zn-ion batteries. Herein, a new strategy of tuning the electrolyte solvation structure and electrode interface is demonstrated for highly reversible zinc plating/stripping. Acetonitrile (AN) is introduced into Zn(OTf)2 electrolyte as co-solvent, the interaction between Zn2+ and acetonitrile attenuates the Zn2+ solvation and water activity. Concomitantly, theoretical calculations demonstrate that acetonitrile molecules tend to adsorb on the surface of zinc electrode to form an adaptive zinc-electrolyte interface. Such an electrolyte engineering significantly prevents water hydrogen evolution, suppresses vanadium dissolution and modulates Zn deposition behavior. As proof of concept, Zn//Zn symmetric cells with acetonitrile additive exhibit a ultra-long cycling of 2100 h at a high current density of 5 mA cm^-2. In particular, the university of the acetonitrile-water co-solvent (AWCS) electrolyte is demonstrated, multiple battery systems (Zn//Al-V-O, Zn//Zn-V-O, Zn//VOOH, and Zn//Mn-V-O) deliver markedly improved cycling stability and rate performance. The mechanism of action of AWCS electrolyte on performance indicators is discussed in detail, which provides a promising insight for energy storage devices.
https://doi.org/10.1016/j.cej.2022.138265
A novel concept for 5D nanopositioning, nanomeasuring and nanofabrication machines :
Ein neuartiges Konzept für 5D Nanopositionier-, Nanomess-, und Nanofabrikationsmaschinen. - In: Technisches Messen, ISSN 2196-7113, Bd. 89 (2022), 9, S. 634-643
In den vergangenen Jahren wurden an der TU-Ilmenau zahlreiche Entwicklungen im Bereich der Nanopositionier- und Nanomesstechnik realisiert. Insbesondere die NMM-1 [Gerd Jäger, Eberhard Manske, Tino Hausotte, Jans-Joachim Büchner, Nanomessmaschine zur abbefehlerfreien Koordinatenmessung, tm - Technisches Messen, 67(7-8), 2000] sowie die NPMM-200 [Eberhard Manske, Gerd Jäger, Tino Hausotte, Felix Balzer, Nanopositioning and Nanomeasuring Machine NPMM-200 - sub-nanometre resolution and highest accuracy in extended macroscopic working areas, euspen’s 17th International Conference, 2017] stellen ein Novum auf dem Gebiet der Koordinatenmesstechnik mit Nanometerpräzision unter Einhaltung des Abbe-Komparatorprinzips [Ernst Abbe, Messaparate für Physiker, Zeitschrift für Instrumentenkunde, 10:446-448, 1890] dar. Ausgehend von diesen Errungenschaften besteht ein nächster Schritt im Messen und Fabrizieren auf stark gekrümmten, asphärischen, oder freigeformten Oberflächen. Vor jenem Hintergrund wird im folgenden Artikel ein Konzept für ein zweiachsiges Rotationsmodul vorgestellt. Dieses dient als Erweiterung für die NMM-1 und ermöglicht über das kartesische Messvolumen von hinaus zusätzlich eine Rotation des Tools über 360 ˚ um die Hochachse sowie 60 ˚ Neigung. Die Umsetzung erfolgt über eine neuartige sphärische Parallelkinematik. Mit Hilfe eines interferometrischen In-Situ-Referenzmesssystems können die während der Rotationsbewegungen auftretenden translatorischen Positionsabweichungen detektiert werden. Erste Untersuchungen an einem Prototypenaufbau erbringen den Funktionsnachweis des Referenzmesssystems über den gesamten adressierbaren Winkelbereich.
https://doi.org/10.1515/teme-2022-0037
Evaluating the optical response of heavily decorated black silicon based on a realistic 3D modeling methodology. - In: ACS applied materials & interfaces, ISSN 1944-8252, Bd. 14 (2022), 31, S. 36189-36199
Combining black silicon (BS), a nanostructured silicon containing highly roughened surface morphology with plasmonic materials, is becoming an attractive approach for greatly enhancing light-matter interactions with promising applications of sensing and light harvesting. However, precisely describing the optical response of a heavily decorated BS structure is still challenging due to the increasing complexity in surface morphology and plasmon hybridization. Here, we propose and fully characterize BS-based multistacked nanostructures with randomly distributed nanoparticles on the highly roughened nonflat surface. We demonstrate a realistic 3D modeling methodology based on parametrized scanning electron microscopy images that provides high-precision morphology details, successfully linking the theoretical analysis with experimental optical response of the complex nanostructures. Far-field calculations very nicely reproduce experimental reflectance spectra, revealing the dependency of light trapping on the thickness of the conformal reflector and the atop nanoparticle size. Near-field analysis clearly identifies three types of stochastic “hotspots”. Their contribution to the overall field enhancement is shown to be very much sensitive to the nanoscale surface morphology. The simulated near-field property is then used to examine the measured surface-enhanced Raman scattering (SERS) response on the multistacked structures. The present modeling approach combined with spectroscopic characterizations is expected to offer a powerful tool for the precise description of the optical response of other large-scale highly disordered realistic 3D systems.
https://doi.org/10.1021/acsami.2c05652
Plasma-assisted fabrication of molecularly imprinted NiAl-LDH layer on Ni nanorod arrays for glyphosate detection. - In: ACS applied materials & interfaces, ISSN 1944-8252, Bd. 14 (2022), 31, S. 35704-35715
An inorganic-framework molecularly imprinted NiAl layered double hydroxide (MI-NiAl-LDH) with specific template molecule (glyphosate pesticide, Glyp) recognition ability was prepared on Ni nanorod arrays (Ni NRAs) through electrodeposition followed by a low-temperature O2 plasma treatment. The freestanding Ni/MI-NiAl-LDH NRA electrode had highly enhanced sensitivity and selectivity. The electrocatalytic oxidation of Glyp was proposed to occur at Ni3+ centers in MI-NiAl-LDH, and the current response depended linearly on the Glyp concentration from 10.0 nmol/L to 1.0 μmol/L (R2 = 0.9906), with the limit of detection (LOD) being 3.1 nmol/L (S/N = 3). An exceptional discriminating capability with tolerance for other similar organophosphorus compounds was achieved. Molecular imprinting (N and P residues) affected the electronic structure of NiAl-LDH, triggering the formation of highly active NiOOH sites at relatively lower anodic potentials and substantially enhancing the electrocatalytic oxidation ability of the NiAl-LDH interface toward the C-N bonds in Glyp. In combination with the surface enrichment effect of MI-NiAl-LDH toward template molecules, the electrochemical oxidation signal intensity of Glyp increased significantly, with a greater peak separation from interfering molecules. These results challenge the common belief that the excellent performance of inorganic-framework molecularly imprinted interfaces arises from their specific adsorption of template molecules, providing new insight into the development of high-performance organic-pollutant-sensing electrodes.
https://doi.org/10.1021/acsami.2c08500
Ellipsometry and polarimetry - classical measurement techniques with always new developments, concepts, and applications. - In: Advanced Optical Technologies, ISSN 2192-8584, Bd. 11 (2022), 3/4, S. 57-58
https://doi.org/10.1515/aot-2022-0025