NMR relaxation dispersion of liquids adsorbed on modified surfaces of SBA-15 mesoporous silica. - In: The journal of physical chemistry, ISSN 1932-7455, Bd. 128 (2024), 21, S. 8785-8796
The NMR relaxation dispersion of 1H and 2H nuclei in water and alkanes was studied in mesoporous SBA-15 silica in its native state and with modified internal surfaces. By comparison with silica gel of comparable characteristic pore size, a qualitative agreement of the relaxation dispersion was found. In the absence of detectable amounts of paramagnetic centers, intramolecular relaxation is approximated by the model of Reorientations Mediated by Translational Displacements (RMTD), which assumes rigid molecules diffusing along curved surfaces and experiencing long-term memory of their relative orientation due to their polarity. For all liquids, significant relaxation dispersion is found so that the vanishing polarity of alkanes does not allow the assumption of a negligible surface interaction. The difference in dispersion shape between 1H and 2H nuclei, relaxing by dipolar and quadrupolar mechanisms, respectively, allows the reconstruction of the intermolecular contribution to relaxation, which has not yet been studied systematically in porous media. A model based on the relative contributions of intra- and intermolecular interactions as well as hydrogen exchange with OH- and NH2-groups is presented.
https://doi.org/10.1021/acs.jpcc.4c00645
Investigating the suitability of various silver(I) complexes for use in a cyanide-free silver electrolyte. - In: Coatings, ISSN 2079-6412, Bd. 14 (2024), 5, 618, S. 1-16
The suitability of various nitrogen, sulfur, oxygen, and phosphorus compounds as complexing agents in a silver electrolyte was examined by using potentiometric titration under practical conditions. The setup consisted of three electrodes to measure the pH and the activity of the silver ions simultaneously. Different ratios of silver to complexing agent from 1:10 to 1:1 at a constant ionic strength of 0.2 mol/L were investigated. The type of the complexes and their corresponding critical stability constants were evaluated by fitting the measured data using a self-developed algorithm. The pH and Nernst potential curve were calculated for the assumed complexes based on the law of mass action to find the best approximation. The correct definition of the occurring species is challenging and can lead to significant changes in the calculation of stability constants. For this reason, the measured silver potential curves were primarily used for the rating of the complexing agents. An evaluation of the measurements shows that the donor atom of the complexing agent and its ligand field strongly affected the stability and type of the complexes. Only a few complexing agents were found to be suitable for use in the cyanide-free silver electrolyte.
https://doi.org/10.3390/coatings14050618
Miniaturized double-wing ∆E-effect magnetic field sensors. - In: Scientific reports, ISSN 2045-2322, Bd. 14 (2024), 11075, S. 1-12
Magnetoelastic micro-electromechanical systems (MEMS) are integral elements of sensors, actuators, and other devices utilizing magnetostriction for their functionality. Their sensitivity typically scales with the saturation magnetostriction and inversely with magnetic anisotropy. However, large saturation magnetostriction and small magnetic anisotropy make the magnetoelastic layer highly susceptible to minuscule anisotropic stress. It is inevitably introduced during the release of the mechanical structure during fabrication and severely impairs the device’s reproducibility, performance, and yield. To avoid the transfer of residual stress to the magnetic layer, we use a shadow mask deposition technology. It is combined with a free-free magnetoelectric microresonator design to minimize the influence of magnetic inhomogeneity on device performance. Magnetoelectric resonators are experimentally and theoretically analyzed regarding local stress anisotropy, magnetic anisotropy, and the ΔE-effect sensitivity in several resonance modes. The results demonstrate an exceptionally small device-to-device variation of the resonance frequency < 0.2% with large sensitivities comparable with macroscopic ΔE-effect magnetic field sensors. This development marks a promising step towards highly reproducible magnetoelastic devices and the feasibility of large-scale, integrated arrays.
https://doi.org/10.1038/s41598-024-59015-5
“I have the feeling that the person is here”: older adults’ attitudes, usage intentions, and requirements for a telepresence robot. - In: International Journal of Social Robotics, ISSN 1875-4805, Bd. 0 (2024), 0, insges. 21 S.
The social integration of older adults has been shown to be vital for successful aging. Innovative communication technologies, such as telepresence robots, can protect older adults against loneliness and social isolation by helping them stay connected to their social networks. This human-centered qualitative study aims to identify the attitudes (research question 1, RQ1), intentions to use (RQ2), and requirements (RQ3) of older adults for robot-mediated communication (RMC) via a telepresence robot. Semi-structured individual interviews were conducted with N = 30 older adults from Germany, who evaluated storyboard illustrations depicting a fictional RMC scenario between a grandparent and their adult grandchild. The study identified 3 attitude groups towards telepresence robots among participants: positive, negative, and conflicting attitudes (RQ1). Furthermore, based on their intentions of use, participants were classified into reluctant future users (n = 12), future non-users (n = 10), and enthusiastic future users (n = 8) (RQ2). Finally, the study identified technological, social, and age-related requirements of older adults for a telepresence robot (RQ3). Practical recommendations are provided based on these findings, such as leveraging older adults’ current technology-related skills, adapting technologies to older adults’ lifestyles and social networks, and designing technologies that contribute to older adults aging in place. This study contributes to the human-centered design of telepresence robots that support the social integration of older adults.
https://doi.org/10.1007/s12369-024-01143-z
Chip-integrated non-mechanical microfluidic pump driven by electrowetting on dielectrics. - In: Lab on a chip, ISSN 1473-0189, Bd. 24 (2024), 11, S. 2893-2905
A microfluidic pump is presented that generates its pumping action via the EWOD (electrowetting-on-dielectric) effect. The flow is generated by the periodic movement of liquid-vapor interfaces in a large number (≈10^6) of microcavities resulting in a volume change of approx. 0.5 pl per cavity per pump stroke. The total flow resulting from all microcavities adds up to a few hundred nanolitres per cycle. Passive, topologically optimized, non-mechanical Tesla valves are used to rectify the flow. As a result, the micropump operates without any moving components. The dimensioning, fabrication, and characterization process of the micropump are described. Device fabrication is done using conventional manufacturing processes from microsystems technology, enabling cost-effective mass production on wafer-level without additional assembly steps like piezo chip-level bonding, etc. This allows for direct integration into wafer-based microfluidic or lab-on-a-chip applications. Furthermore, first measurement results obtained with prototypes of the micropump are presented. The voltage- and frequency-dependent pump performance is determined. The measurements show that a continuous flow rate larger than 0.2 ml min^−1 can be achieved at a maximum pump pressure larger than 12 mbar.
https://doi.org/10.1039/D4LC00178H
Yu-Shiba-Rusinov states induced by single Fe atoms on reconstructed compound superconductor V3Si. - In: Surface science, ISSN 1879-2758, Bd. 746 (2024), 122504, S. 1-10
Reconstructed surfaces of the A15-compound superconductor V3Si(100) that are possibly induced by the segregation of bulk impurities serve as platforms to study the dependence of Yu-Shiba-Rusinov states induced by a single Fe atom on the adsorption site. Their number, energy and electron-hole asymmetry vary strongly with the atomic environment of the Fe atom. These variations are indicative of different Fe d-orbitals being active in the site-dependent exchange coupling with the substrate Cooper pairs. Spatially resolved spectroscopy gives rise to a short decay length of the Yu-Shiba-Rusinov states and thereby suggests the three-dimensional character of the scattering process underlying the bound states.
https://doi.org/10.1016/j.susc.2024.122504
Broadband DRA with uniform angular dependent delay for indoor localization. - In: IEEE access, ISSN 2169-3536, Bd. 12 (2024), S. 63644-63654
Estimating the Time Difference of Arrival (TDoA), is a simple yet reliable technique to accurately perform an indoor monostatic localization. To implement TDoA estimation, one approach is to utilize a broadband radar system equipped with multiple receiving antenna elements. To obtain the Time of Arrival (ToA) at each antenna element, the round-trip time is required. However, the round-trip time does not only consist of the propagation delay in free space but the propagation delay within the antenna as well. To perform the localization precisely, it is desired that an antenna element introduces a uniform delay in all directions. To this end, a compact rectangular dielectric resonator antenna is designed for the operating frequency of 6.5 GHz with a fractional bandwidth of 20%. Al2O3 with a dielectric constant of 9.8 is used for the substrate as well as the dielectric resonator. The antenna is designed to provide a high correlation between the input and the output pulses. To investigate the correlation, the antenna is excited with a modulated Gaussian pulse and the radiated pulses are studied. The antenna possesses an excellent behavior in terms of pulse preservation for the upper hemisphere. Therefore, when incoming pulses from the same distance but different directions impinge on the antenna, they reach the port of the antenna at a similar time. It is shown that this feature of the proposed antenna allows the utilization of TDoA estimation without the need for a calibration step. The characteristics of the antenna are verified by simulation and measurement.
https://doi.org/10.1109/ACCESS.2024.3395124
An experiment on the press coverage of child sexual abuse: can readers differentiate between good and bad reporting?. - In: Mass communication & society, ISSN 1532-7825, Bd. 0 (2024), 0, S. 1-23
News reporting on child sexual abuse (CSA) plays an important role in educating the public and fighting sexual violence, according to the public interest model of normative media theory. Bad reporting, however, is widespread and hinders a solution-oriented approach. Against this backdrop, the current study investigated which normative and subjective criteria are used by readers when they assess the quality of CSA newspaper reporting (RQ1). Furthermore, it was tested if readers can differentiate between good and bad CSA reporting quality (RQ2) and if their personal involvement in the topic - concerning victimization, exposure to CSA reporting, CSA knowledge - influences assessments of journalistic quality (RQ3). An experimental online study with a national quota sample of N = 2724 adults (18–65 years; Mage = 44.1; 52.5% women) from Germany was conducted in 2020. The study is preregistered and further materials are shared on osf.io. It turned out that readers mostly used the normative criteria to assess CSA reporting quality that are suggested by the academic literature (RQ1). Readers were able to differentiate between CSA reporting with high versus low journalistic quality (RQ2) - irrespective of their own CSA victimization (RQ3). Readers rated bad reporting as mediocre, though, indicating potential unawareness of certain quality issues.
https://doi.org/10.1080/15205436.2024.2335344
Research in brief: how prevalent is rough sex? Results from a national online sample of adults in Germany. - In: Perspectives on sexual and reproductive health, ISSN 1931-2393, Bd. 56 (2024), 2, S. 90-97
Background: Rough sex refers to consensual sexual activities that incorporate playful aggression, such as hair pulling, spanking, or choking. It is relevant in the context of sexual health as it can enhance sexual arousal, pleasure, and intimacy among consenting partners. However, it can also be associated with consent violations, discomfort, and injuries ranging from mild to severe or even fatal. The prevalence of rough sex in Germany is widely unknown. Our study aims to establish, for the first time, the overall age-related and gender-related prevalence rates of active and passive rough sex involvement among adults in Germany. Methods: A national online sample of 1101 adults from Germany, aged 18-69 years (50% men, 49% women, 1% gender-diverse individuals) gave informed consent and reported on their lifetime engagement in rough sex in active and passive roles. We recruited participants through a professional panel provider for a multi-themed sexual health survey. Data analysis was conducted using R, with 95% confidence intervals of prevalence rates computed to answer the research questions. Results: Lifetime prevalence of rough sex involvement was 29%. Adults below the age of 40 reported higher rates of involvement (up to 43%) than people over 40 (up to 26%). Men reported predominantly active role involvement and women reported primarily passive role involvement. Discussion: Results show that rough sex is common. Sexual health professionals, educators, and researchers should be prepared to guide current and aspiring practitioners of rough sex, helping them understand potential benefits, risks, and age- and gender-related differences.
https://doi.org/10.1111/psrh.12267
Dynamic characterization of Fiber Bragg Grating temperature sensors. - In: Experimental thermal and fluid science, Bd. 156 (2024), 111222, S. 1-10
To reliably characterize fast dynamic heat transfer mechanisms, fast-response temperature sensors are crucial, including knowledge about the temporal response. In this paper, the dynamic behavior of a Fiber Bragg Grating temperature sensor is investigated and compared to different types of fast-response thermocouples using two different experimental dynamic characterization methods. A temperature step is generated by either plunging the sensor into a fluid or exposing it to a fluid droplet at different temperatures. The step response is evaluated to determine the sensor response time. Calibration runs are performed for a silica-based 0.1 mm FBG sensor, as well as for 0.16 mm and 0.8 mm exposed tip and 0.25 mm sheathed tip type K thermocouples. Water, glycerin, oil and GaInSn were used to cover a broad range of applications regarding different thermal diffusivities and viscosities. The FBG sensor showed the shortest response times compared to the thermocouples, ranging from 60 ms in oil down to 3 ms in liquid metal, which is 20% up to 70% faster compared to a 0.25 mm sheathed tip type K thermocouple. Additional plunging calibration runs of the FBG sensor were performed in a ternary nitrate molten salt mixture (HITEC) to determine its overall and dynamic behavior in corrosive fluids at elevated temperatures. It turns out that the FBG sensor is not affected by the molten salt and shows similar response times to those measured in water. Regarding the characterization methods, both techniques show reproducible results, even though the droplet method is inapplicable for sensors with higher heat capacity or lower thermal conductivity than the calibration fluid. Furthermore, splashing effects for fluids with low viscosity reduce the reliability of the droplet method. The results also show that a dynamic characterization is indispensable for temperature measurements with high temporal resolution because the response time depends on the sensor size and the heat transfer coefficient between sensor and surrounding, which in turn depends on the sensor type, fluid properties and the flow parameters.
https://doi.org/10.1016/j.expthermflusci.2024.111222