77823 research outputs found
Sort by
Improving transport efficiency for large human cells for enabling accurate determination of cellular nanoparticle uptake via SC-ICP-TOF-MS
No full textSingle-cell inductively coupled plasma-mass spectrometry (SC-ICP-MS) provides high-throughput, quantitative information on nanoparticle (NP)–cell interaction, but its application to larger mammalian cells remains limited due to the low transport efficiency (TE) provided by commercially available introduction systems. In this study, we have addressed this challenge by working at a higher spray chamber temperature (150 °C), which led to a 81-fold increase in TE for A549 human lung carcinoma cells (measured size of ∼20 μm). This observation was also validated using other cell types with different sizes and morphologies, such as red blood cells (∼6 μm) and Raji cells (∼11 μm), for which respective TE improvements of 2.3- and 13-fold were observed. Coupling the optimized setup to a time-of-flight ICP-MS (ICP-TOF-MS) unit enabled quasi-simultaneous monitoring of nearly the entire elemental mass range, allowing clear differentiation between a) cells with AuNPs, b) cells without AuNPs, and c) free AuNPs, by simultaneously monitoring the presence of cellular components (P, Zn), NPs (Au), and a DNA intercalator (Ir). The method developed was subsequently applied to study the uptake of AuNPs in cells, which is relevant for fields like drug delivery and nanotoxicology. Quantification of the number of AuNPs per cell across varying NP concentrations revealed an overdispersed Poisson distribution, consistent with theoretical expectations. Further method validation via LA-ICP-TOF-MS was used to confirm the biological relevance of the results. Overall, this study presents a robust SC-ICP-MS workflow for studying large human cells and demonstrates its utility in studying the uptake of metallic NPs in cells
Household commuting time and job changes
No full textCommuting, job change, and residential relocation significantly impact workers’ quality of life, labor market dynamics, and urban planning. Furthermore, commuting also relates to life events within the household, especially those related to spatial choices, but existing research often overlooks the intricacies of the dynamic behaviors and responses to these events. This study explores how job changes and residential relocations impact commuting times within married couples, contributing to the literature on commuting, job mobility, and household decision-making dynamics. Using data from the Panel Study of Income Dynamics (2011–2019), we examine patterns in commuting times following job transitions. Our findings reveal that when husbands change jobs, their commuting time generally decreases, while wives’ commuting times remain largely unaffected. Conversely, wives experience an increase in commuting time upon changing jobs, only if the job change leads to a higher wage. In cases where both spouses change jobs simultaneously, the husband’s commuting time rises significantly, whereas the wife’s commuting time shows no change. This research provides new insights into the joint decision-making processes within households, emphasizing the interplay between job changes and commuting behavior at the household level. These findings hold implications for policies aimed at supporting equitable access to well-connected job opportunities, particularly to accommodate longer commutes associated with specific job changes, while considering the distinct commuting patterns of dual-earner households
Treasure hunt in emerging markets: Empirical evidence for European pension funds
Full text linkThis research analyzes the European pension funds' exposure to emerging markets, its evolution over time, and its impact on financial performance. For this aim, we study a sample formed by 822 European pension funds with an international equity investment vocation, covering the period from June 2008 to June 2024. To assess the impact of emerging markets exposure on financial performance, we employ panel regression models with time and fund fixed effects and robust standard errors. Our findings indicate that the average weight of the emerging markets in the portfolios analyzed is 25.44 %, with the highest weight reached in 2017 (28.5 %). When focusing on specific emerging markets/regions, the findings show that the weight of Asia Emerging has increased over time to the detriment of other markets such as Europe Emerging, Africa, or Latin America. The impact of the emerging market exposure on financial performance is mixed depending on the market analyzed and the period considered. Overall, greater exposure to the BRICS markets positively affects the performance achieved by pension funds' managers. Another finding reveals that pension fund managers seem to adjust their portfolio’s country/regional allocation over time, increasing the weight of emerging markets that positively impact financial performance, which provides added value to investors
Community challenge towards consensus on characterization of biological tissue: C4Bio’s first findings
No full textThis study investigates methodological variability across various expert laboratories worldwide, with regards to characterizing the mechanical properties of biological tissues. Two testing rounds were conducted on the specific use case of uniaxial tensile testing of porcine aorta. In the first round, 24 labs were invited to apply their established methods to assess inter-laboratory variability. This revealed significant methodological diversity and associated variability in the stress–stretch results, underscoring the necessity for a standardized approach.
In the second round, a consensus protocol was collaboratively developed and adopted by 19 labs in an attempt to minimize variability. This involved standardized sample preparation and uniformity in testing protocol, including the use of a common cutting and thickness measurement tool. Despite protocol harmonization, significant variability persisted across labs, which could not be solely attributed to inherent biological differences in tissue samples.
These results illustrate the challenges in unifying testing methods across different research settings, underlining the necessity for further refinement of testing practices. Enhancing consistency in biomechanical experiments is pivotal when comparing results across studies, as well as when using the resulting material properties for in silico simulations in medical research
Regular fractional weighted Wiener algebras and invariant subspaces
Full text linkSince the fifties, the interplay between spectral theory, harmonic analysis and a wide variety of techniques based on the functional calculus of operators, has provided useful criteria to find non-trivial closed invariant subspaces for operators acting on complex Banach spaces. In this article, some standard summability methods (mainly the Cesàro summation) are applied to generalize classical results due to Wermer [51] and Atzmon [8] regarding the existence of invariant subspaces under growth conditions on the resolvent of an operator. To do so, an extension of Beurling's regularity criterion [13] is proved for fractional weighted Wiener algebras related with the Cesàro summation of order . At the end of the article, other summability methods are considered for the purpose of finding new sufficient criteria which ensure the existence of invariant subspaces, resulting in several open questions on the regularity of fractional weighted Wiener algebras associated to matrix summation methods defined from non-vanishing complex sequences
Doped In2O3/ZrO2 catalysts to drive selectivity toward DME in one-pot CO2 hydrogenation
Full text linkThis study investigates single-pass dimethyl ether synthesis at mild pressure conditions using novel bifunctional catalysts based on indium-modified formulations and incorporating Ni, Cu, Pt, and Pd as active metals. Additionally, the substitution of the conventional HZSM-5 zeolite with 4A zeolite as the dehydration component was evaluated. Although 4A zeolite exhibited lower dehydration activity, it contributed to an overall improvement in DME selectivity. The incorporation of secondary metals into the In2O3-ZrO2 formulation reduced catalytic activity but enhanced selectivity, ultimately increasing DME yield. The formation of by-products such as light olefins and methane was significantly dependent on the metal used: Ni, Pt, and Pd reduced olefin production, though Ni promoted excessive methane formation across the whole temperature range. Notably, the Pt-based catalyst completely suppressed by-product formation across the temperature range studied. While the In2O3-ZrO2-based catalysts generally displayed lower space–time yields than the commercial reference, they achieved comparable performance at 280 °C. Due to their superior selectivity, these formulations are promising for developing even better performing catalysts, to be excellent candidates in industrial processes, where the operation with recycle loops requires a high product purity
Effective H2 conversion to substitute natural gas on Ni-based catalysts: role of promoters and synthesis method
No full textThe methanation of CO2 is crucial for Power-to-Gas technologies, enabling synthetic natural gas production from renewable sources. Catalyst formulation is key to tuning activity, selectivity, and reaction mechanisms. This study examines CeO2-ZrO2-supported catalysts with low Ni loading, evaluating Ru as a promoter. A detailed kinetic analysis clarifies the roles of Ni and Ru in CO2 hydrogenation, CO methanation, and the reverse water-gas shift (rWGS) reaction. Ni-based catalysts showed high activity for CO and rWGS reactions, with significantly higher rate constants than Ru-based systems. In contrast, Ru was most active for direct CO2 methanation but had negligible activity for CO methanation, resulting in lower CH4 selectivity when used alone. Mechanistic studies indicate that Ni promotes a stepwise pathway (CO2 → CO → CH4), while Ru facilitates direct CO2 hydrogenation. Co-impregnation of Ni and Ru enhanced both activity and selectivity, highlighting a synergistic effect. Among all formulations, the sequentially impregnated RuNi/CeZr_TSI catalyst outperformed others. Its success stems from combining Ru strong initial CO2 activation with Ni high CO methanation ability, leading to greater CO2 conversion and CH4 selectivity across a wide temperature range. These results confirm the promise of Ni-Ru/CeO2-ZrO2 catalysts for efficient renewable methane production
Tailoring Ca0.99Ce0.01MnO3 properties using Mo doping and its integration in a power generation thermoelectric module
No full textIn the present study, we examined both the crystal structure and thermoelectric behavior of Ca0.99Ce0.01Mn1-xMoxO3 compositions, with Mo concentrations set at x = 0, 0.01, 0.03, 0.05, and 0.10. From XRD experiment, it is observed that most of the peaks can be indexed in a Pnma space group. Furthermore, Mo has effectively substituted Mn into the unit cell revealed by the shift of the diffraction peaks towards lower angles. SEM images showed a grain refinement with the increase in Mo doping, suggesting that it acts as grain growth inhibitor. Moreover, a decrease of porosity is observed when the amount of dopant is raised up to 0.05, increasing for higher Mo content. EDS analysis conducted on various regions of the samples shows that the grain compositions closely match the nominal values. Resistivity data show that the undoped sample exhibits both metallic-like and semiconducting-like behavior, whereas Mo doping induces metallic-like behavior throughout the entire temperature range. The lowest resistivity at 800 °C (∼ 6.5 mΩ cm) was recorded for the 0.10 Mo-substituted sample, which is comparable to the values found in the 0.03 and 0.05 Mo-doped samples, and significantly lower than that of the undoped sample. The evolution of the Seebeck coefficient as a function of composition and temperature demonstrated that all samples exhibit negative S values within the measured range of temperatures. The highest |S| values at 800 °C were measured in the Mo-free samples (213 μV/K), very close to that of the 0.01Mo-doped samples (207 μV/K). Highest PF measured at 800 °C were obtained in 0.01Mo-doped samples (∼ 0.36 mW/K2m), which are between 13 and 30 % higher than those obtained in 0.0, 0.03, and 0.05Mo-doped samples. Finally, a power generation thermoelectric module with 17 p-n pairs, and 50 × 50 mm2 surface, has been successfully prepared using 0.01Mo doped samples and Ca2.93Sr0.07Co4O9, which has produced 0.045 W maximum power at 900 °C hot-side temperature, under 358 °C internal ΔT. Taking into account the module surface (2500 mm2) and the maximum power generated (45 mW), a high power density of 18 W/m2 has been obtained
Optimal operation and marginal costs in a complex polygeneration system including thermal energy storage and DHCN pipelines
Full text linkThis paper proposes a thermoeconomic analysis to determine the hourly marginal costs of the optimal operation of a complex polygeneration system when the energy demand for a specific energy service increases at any time step, without modifying the operation mode of the system. The work analyses a case study which considers a mixed integer linear programming (MILP) model of an energy community (EC), comprising nine tertiary sector buildings and a central unit supplied by natural gas, solar energy, and electricity. The buildings exchange electricity through a local electric grid as well as heating and cooling through a district heating and cooling network (DHCN). The paper focuses on the marginal cost (MC) analysis of the electricity and heating demands regarding two of the EC buildings by evaluating representative time steps of a typical winter day. Additionally, a detailed analysis of the cost formation process for polygeneration heat production is conducted, clarifying the influence of thermal energy storage (TES) and DHCN on the marginal cost of heat production. The proposed marginal cost analysis reveals strategies for managing increased heat or electricity demands with minimal impact on the objective function. While the applied methodology offers robustness and transparency, it should be noted that the model under analysis does not include dynamic inefficiencies such as start-up/shut-down of technologies, and renewable variability is represented through deterministic time series. Thus, the mentioned optimal operation refers to the most cost-effective response to marginal demand changes within fixed operational modes. Obtained results indicate that optimal marginal paths have the potential to reduce operation costs by 26% compared to non-optimal ones
Collecting a large number of alters in egocentric network research: A comparative analysis of three approaches
No full textThis article presents an analysis of the impact of the number of alters elicited in an ego network on the structural properties of those networks. There continues to be debate about the pros and cons of eliciting a fixed number of alters for each respondent versus allowing the respondent to list as many or few alters as they would like. This article explores a random assignment of respondents to three treatment groups – (1) a fixed number of alters set at 30, (2) a variable number of alters up to 45, and (3) a variable number of alters up to 45 with a 20 alter minimum. The results indicate that, from a non-structural perspective, all levels of emotional proximity, interaction contexts, genders, and ages are consistently sampled across the three treatment groups. At the structural level, the behavior of individual metrics is also largely similar. However, the most significant differences arise in the collective behavior of structural metrics—specifically, in their correlation structure, the amount of redundant information each variable provides, and the diversity and interpretability of the observed structural variability. When a data collection strategy constrains network size, it reduces the sparsity of the correlation matrix, effectively decreasing the number of independent global variables needed to describe network structure and making these global variables less interpretable. In other words, networks constructed with a survey that limits size tend to be more similar to each other, exhibiting less structural diversity and yielding differences that are harder to interpret. However, we discuss how these differences may simply be mathematical artifacts, without necessarily implying a clear advantage in choosing one treatment over another. Finally, we argue that the field needs a targeted study to answer whether the differing numbers of alters listed is a function of network size