Three-dimensional platinum nanoparticle-based bridges for ammonia gas sensing. - In: Scientific reports, ISSN 2045-2322, Bd. 11 (2021), 12551, S. 1-9
This study demonstrates the fabrication of self-aligning three-dimensional (3D) platinum bridges for ammonia gas sensing using gas-phase electrodeposition. This deposition scheme can guide charged nanoparticles to predetermined locations on a surface with sub-micrometer resolution. A shutter-free deposition is possible, preventing the use of additional steps for lift-off and improving material yield. This method uses a spark discharge-based platinum nanoparticle source in combination with sequentially biased surface electrodes and charged photoresist patterns on a glass substrate. In this way, the parallel growth of multiple sensing nodes, in this case 3D self-aligning nanoparticle-based bridges, is accomplished. An array containing 360 locally grown bridges made out of 5 nm platinum nanoparticles is fabricated. The high surface-to-volume ratio of the 3D bridge morphology enables fast response and room temperature operated sensing capabilities. The bridges are preconditioned for ˜ 24 h in nitrogen gas before being used for performance testing, ensuring drift-free sensor performance. In this study, platinum bridges are demonstrated to detect ammonia (NH3) with concentrations between 1400 and 100 ppm. The sensing mechanism, response times, cross-sensitivity, selectivity, and sensor stability are discussed. The device showed a sensor response of ˜ 4% at 100 ppm NH3 with a 70% response time of 8 min at room temperature.
https://doi.org/10.1038/s41598-021-91975-w
Electrical conductivity adjustment for interface capacitive-like storage in sodium-ion battery. - In: Advanced functional materials, ISSN 1616-3028, Bd. 31 (2021), 24, 2101081, insges. 11 S.
Sodium-ion battery (SIB) is significant for grid-scale energy storage. However, a large radius of Na ions raises the difficulties of ion intercalation, hindering the electrochemical performance during fast charge/discharge. Conventional strategies to promote rate performance focus on the optimization of ion diffusion. Improving interface capacitive-like storage by tuning the electrical conductivity of electrodes is also expected to combine the features of the high energy density of batteries and the high power density of capacitors. Inspired by this concept, an oxide-metal sandwich 3D-ordered macroporous architecture (3DOM) stands out as a superior anode candidate for high-rate SIBs. Taking Ni-TiO2 sandwich 3DOM as a proof-of-concept, anatase TiO2 delivers a reversible capacity of 233.3 mAh g^-1 in half-cells and 210.1 mAh g^-1 in full-cells after 100 cycles at 50 mA g^-1. At the high charge/discharge rate of 5000 mA g^-1, 104.4 mAh g^-1 in half-cells and 68 mAh g^-1 in full-cells can also be obtained with satisfying stability. In-depth analysis of electrochemical kinetics evidence that the dominated interface capacitive-like storage enables ultrafast uptaking and releasing of Na-ions. This understanding between electrical conductivity and rate performance of SIBs is expected to guild future design to realize effective energy storage.
https://doi.org/10.1002/adfm.202101081
Improving the performance of a radio-frequency localization system in adverse outdoor applications. - In: EURASIP journal on wireless communications and networking, ISSN 1687-1499, (2021), 123, S. 1-26
In outdoor RF localization systems, particularly where line of sight can not be guaranteed or where multipath effects are severe, information about the terrain may improve the position estimate's performance. Given the difficulties in obtaining real data, a ray-tracing fingerprint is a viable option. Nevertheless, although presenting good simulation results, the performance of systems trained with simulated features only suffer degradation when employed to process real-life data. This work intends to improve the localization accuracy when using ray-tracing fingerprints and a few field data obtained from an adverse environment where a large number of measurements is not an option. We employ a machine learning (ML) algorithm to explore the multipath information. We selected algorithms random forest and gradient boosting; both considered efficient tools in the literature. In a strict simulation scenario (simulated data for training, validating, and testing), we obtained the same good results found in the literature (error around 2 m). In a real-world system (simulated data for training, real data for validating and testing), both ML algorithms resulted in a mean positioning error around 100 ,m. We have also obtained experimental results for noisy (artificially added Gaussian noise) and mismatched (with a null subset of) features. From the simulations carried out in this work, our study revealed that enhancing the ML model with a few real-world data improves localization’s overall performance. From the machine ML algorithms employed herein, we also observed that, under noisy conditions, the random forest algorithm achieved a slightly better result than the gradient boosting algorithm. However, they achieved similar results in a mismatch experiment. This work’s practical implication is that multipath information, once rejected in old localization techniques, now represents a significant source of information whenever we have prior knowledge to train the ML algorithm.
https://doi.org/10.1186/s13638-021-02001-6
The business model data facilitator in consulting :
Das Geschäftsmodell Data Facilitator im Consulting. - In: HMD, ISSN 2198-2775, Bd. 58 (2021), 3, S. 552-564
Mit der Vervielfachung des Datenvolumens und der raschen Weiterentwicklung entsprechender Analysemethoden und Werkzeuge gibt es immer mehr Unternehmen, insbesondere aus dem kleineren Mittelstand, die aufgrund mangelnder Ressourcen und Fähigkeiten nicht in der Lage sind, ihre Datenschätze zu heben und daraus gute Entscheidungen im Hinblick auf ihre Produkte, Prozesse und Geschäftsmodelle abzuleiten. Vor diesem Hintergrund wird im vorliegenden Beitrag ein Data Facilitator Geschäftsmodell für Consultingunternehmen vorgeschlagen. Um nicht im Wettbewerb zurückzufallen, lagern hierin Unternehmen Aufgaben der Datenaufbereitung, Analyse und Interpretation an ein Beratungsunternehmen aus, das sich auf solche Themen spezialisiert hat. Berater erhalten dabei Zugriff auf kritische Datenströme des Kunden, die dann auf regelmäßiger Basis fachkundig, unter Einsatz moderner Analyseinstrumente untersucht werden. Es geht darum, frühzeitig "schwache Signale" für zukünftige kritische Entwicklungen beim Kunden zu erkennen oder Ideen für geschäftliche Verbesserungen zu entwickeln. Dabei werden die Ergebnisse dem Kunden nicht kommentarlos übermittelt, sondern Auffälligkeiten von den Beratern unter Einbringung ihres Fachwissens mit den Kunden diskutiert und interpretiert. Der Kunde trifft dann gegebenenfalls Entscheidungen auf Basis der vorliegenden Datenlage. Da diese Dienstleistung fortlaufend erbracht wird, sind hierfür neue Bezahlmodelle im Consulting sinnvoll, wie z.B. eine monatliche Pauschale. Für eine erfolgreiche Umsetzung des Geschäftsmodells sind in der Praxis eine Reihe von Problemen zu bewältigen, worauf im Beitrag ebenfalls eingegangen wird.
https://doi.org/10.1365/s40702-021-00723-1
Alcohol in social media: where is the space for prevention? :
Alkohol in sozialen Medien: wo ist der Platz für Prävention?. - In: Bundesgesundheitsblatt, Gesundheitsforschung, Gesundheitsschutz, ISSN 1437-1588, Bd. 64 (2021), 6, S. 697-706
https://doi.org/10.1007/s00103-021-03335-8
Study on friction in automotive shock absorbers, part 2: Validation of friction simulations via novel single friction point test rigs. - In: Vehicles, ISSN 2624-8921, Bd. 3 (2021), 2, S. 197-211
https://doi.org/10.3390/vehicles3020013
Study on friction in automotive shock absorbers, part 1: Friction simulation using a dynamic friction model in the contact zone of an FEM model. - In: Vehicles, ISSN 2624-8921, Bd. 3 (2021), 2, S. 212-232
https://doi.org/10.3390/vehicles3020014
Analysis of biomechanical parameters of muscle soleus contraction and blood biochemical parameters in rat with chronic glyphosate intoxication and therapeutic use of C60 fullerene. - In: International journal of molecular sciences, ISSN 1422-0067, Bd. 22 (2021), 9, 4977, S. 1-11
https://doi.org/10.3390/ijms22094977
Insight into nickel-cobalt oxysulfide nanowires as advanced anode for sodium-ion capacitors. - In: Advanced energy materials, ISSN 1614-6840, Bd. 11 (2021), 18, 2100408, insges. 9 S.
Transition metal oxides have a great potential in sodium-ion capacitors (SICs) due to their pronouncedly higher capacity and low cost. However, their poor conductivity and fragile structure hinder their development. Herein, core-shell-like nickel-cobalt oxysulfide (NCOS) nanowires are synthesized and demonstrated as an advanced SICs anode. The bimetallic oxysulfide with multiple cation valence can promote the sodium ion adsorption and redox reaction, massive defects enable accommodation of the volume change in the sodiation/desodiation process, meanwhile the core-shell-like structure provides abundant channels for fast transfer of sodium ions, thereby synergistically making the NCOS electrode exhibit a high reversible sodium ion storage capacity (1468.5 mAh g^-1 at 0.1 A g^-1) and an excellent cyclability (90.5% capacity retention after 1000 cycles). The in-situ X-ray diffraction analysis unravels the insertion and conversion mechanism for sodium storage in NCOS, and the enhanced capability of NCOS is further verified by the kinetic analysis and theoretical calculations. Finally, SICs consisting of the NCOS anode and a boron-nitrogen co-doped carbon nanotubes cathode deliver an energy density of 205.7 Wh kg^-1, a power density of 22.5 kW kg^-1, and an outstanding cycling lifespan. These results indicate an efficient strategy in designing a high-performance anode for sodium storage based on bimetallic dianion compounds.
https://doi.org/10.1002/aenm.202100408
Ultrafast formation of single phase B2 AlCoCrFeNi high entropy alloy films by reactive Ni/Al multilayers as heat source. - In: Materials and design, ISSN 1873-4197, Bd. 206 (2021), 109790, insges. 12 S.
High entropy alloy films of AlCoCrFeNi B2-ordered structure are formed during an ultrafast heating process by reactive Ni/Al multilayers. The self-propagating high-temperature reaction occurring in reactive Ni/Al multilayers after ignition represents an ultrafast heat source which is used for the transformation of a thin films Al/CoFe/CrNi multilayer structure into a single-phase high entropy alloy film. The materials design of the combined multilayers thus determines the phase formation. Conventional rapid thermal annealing transforms the multilayer into a film with multiple equilibrium phases. Ultrafast combustion synthesis produces films with ultrafine-grained single-phase B2-ordered compound alloy. The heating rates during the combustion synthesis are in the order of one million K/s, much higher than those of the rapid thermal annealing, which is about 7 K/s. The results are compared with differential scanning calorimetry experiments with heating rates ranging from about 100 K/s up to 25000 K/s. It is shown that the heating rate clearly determines the phase formation in the multilayers. The rapid kinetics of the combustion prevents long-range diffusion and promotes the run-away transformation. Thus, multilayer combustion synthesis using reactive Ni/Al multilayers as heat source represents a new pathway for the fabrication of single phase high-entropy alloy films.
https://doi.org/10.1016/j.matdes.2021.109790