Browse Articles

Calculation of semiconductor melting temperatures based on Fan-equation approximated by the 37% rule

We present a mathematical model capable of the calculation of semiconductor melting temperatures. Notably, and quite different from previous attempts, the procedure does not require specific knowledge about the thermodynamics of the materials and is based on the Fan equation and the 1/e rule, also known as the 37% rule. Employing this new model, we calculated melting temperatures for 14 semiconductors spanning a wide range of bandgap energies. The results found are in good agreement with previous theoretical and experimental values reported in the literature, establishing the strength of the model in spite of its simplicity. The model also unifies elements and compounds with representative linear trends, showcasing the potential for future expansion.

An analytical model of label-free nanoscale chemical imaging reveals avenues toward improved spatial resolution and sensitivity

Atomic force microscopy–infrared spectroscopy (AFM-IR) is a photothermal scanning probe technique that combines nanoscale spatial resolution with the chemical analysis capability of mid-infrared spectroscopy. Using this hybrid technique, chemical identification down to the single molecule level has been demonstrated. However, the mechanism at the heart of AFM-IR, the transduction of local photothermal heating to cantilever deflection, is still not fully understood. Existing physical models only describe this process in few special cases but not in many of the types of sample geometries encountered in the practical use of AFM-IR. In this work, an analytical expression for modeling the temperature and photothermal expansion process is introduced, verified with finite element simulations, and validated with AFM-IR experiments. This method describes AFM-IR signal amplitudes in vertically and laterally heterogeneous samples and allows studying the effect of position and size of an absorber, pump laser repetition rate and pulse width on AFM-IR signal amplitudes and spatial resolution. The analytical model can be used to identify optimal AFM-IR experimental settings in conventional and advanced AFM-IR modes (e.g., tapping mode, surface-sensitive mode). The model also paves the way for signal inversion based superresolution AFM-IR.

Correction: Intersecting paths: Corporate and green innovation in Chinese firms—A penal cointegration analysis

Optimal power-law fluid flow in tree-like branching networks with self-similar and uniform roughness models

This study presents an analytical model for the flow of a power-law non-Newtonian fluid through a roughened tree-like branching network under volume and surface area constraints. We assume steady-state, axisymmetric, and laminar flow with non-slip boundary conditions along the network walls. We investigate and compare two different roughness models. In the first model, the roughness length scale is self-similar and aligns with the branching network pattern, while in the second model, the surface roughness length scale is uniform. We find that in the case of the self-similar roughness model, the effective conductance remains the same as that of the smooth network. However, in the case of the uniform roughness model, the effective conductance presents an overall decrease. We argue that the uniform roughness model is a more realistic one. Furthermore, the optimal effective conductance, Eopt, and the critical diameter ratio βc, are analyzed as functions of network geometry and fluid rheology. Under both volume and surface area constraints, increasing geometrical parameters such as the number of daughter branches and network generations, generally reduced Eopt, especially for shear-thickening fluids, while shear-thinning fluids were less affected. In macroscopic networks, where roughness is relatively small, the effect of roughness on Eopt is negligible; however, in microscopic networks, where roughness approaches the scale of the diameters of the smallest branches, it leads to pronounced conductance reduction. Furthermore, networks under surface area constraint show significantly lower Eopt values compared to volume-constrained systems. Moreover, we find that the uniform surface roughness model predicts scaling laws for optimal flow (at βc) that vary with all geometrical and rheological parameters. Finally, for macroscopic networks under the uniform roughness assumption, an approximation for βc was derived using linearization with respect to the roughness intensity parameter, and it was found to be in good agreement with the full model equations.

Violence against women and girls research: Leveraging gains across disciplines

Violence against women and girls (VAWG) is a leading cause of mortality and morbidity worldwide, linked to numerous health, economic, and human rights outcomes. Target 5.2 of the Sustainable Development Goals calls for elimination of all forms of VAWG; however, progress toward achieving this goal has been inadequate. A lack of sufficient data and evidence has hindered global efforts to meet this target and hold governments accountable for action. While there have been substantial advancements in VAWG research methodology over the past three decades, researchers from diverse disciplines tend to work in silos, inhibiting progress in VAWG research. To address this challenge, we offer four key recommendations to support researchers in expanding transdisciplinary approaches: 1) leverage insights from a variety of VAWG data sources, 2) improve precision of VAWG definitions and outcomes, 3) create strategies to address underreporting, and 4) advance research ethics and equity. We conclude with a call to action for researchers, institutions, and donors to advance transdisciplinary research and foster collaboration, learning, and cross-fertilization across scientific fields to accelerate VAWG prevention efforts now and for future generations.

Correction: The moderating role of sociodemographic and work-related variables in burnout and mental health levels of Mexican medical residents

Publisher's note: “A 1 kV sub-nanosecond electrical pulse generated by a linear GaAs photoconductive semiconductor switch and its characterization” [J. Appl. Phys. 137, 024504 (2025)]

Molecular glue for phycobilisome attachment to photosystem II in <i>Synechococcus</i> sp. PCC 7002

Phycobilisomes (PBS) are the major photosynthetic light-harvesting complexes in cyanobacteria and red algae. While the structures of PBS have been determined in atomic resolutions, how PBS are attached to the reaction centers of photosystems remains less clear. Here, we report that a linker protein (LcpA) is required for the attachment of PBS to photosystem II (PSII) in the cyanobacterium Synechococcus sp. PCC 7002. We also report that the PB-loop of PBS, which is located within the α-APC domain of ApcE, is required for the attachment of PBS to PSII. Deletion of either PB-loop or the gene A0913 led to a decreased rate of photoautotrophic growth under illumination of green light, which is preferentially absorbed by PBS. A double mutant lacking the PB-loop and A0913 (ΔPBL-0913) showed a complete inhibition of O 2 evolution under the 590 nm light and could not grow under green light illumination. While assembled PBS could be isolated from ΔPBL-0913, the energy transfer from its PBS to PSII was blocked as measured by fluorescence induction. Photobleaching with intact cells showed that the PBS movement speed in ΔPBL-0913 was 2.5 times as fast as that of the wild type, suggesting that association of its PBS with thylakoids was weakened significantly. The pull-down and coimmunoprecipitation results showed that the LcpA interacts with the CP47 subunit of PSII through its N-terminal region and interacts with ApcB of PBS through its C-terminal α-helix motif. Our results provide insights into the molecular mechanism of PBS–PSII association and shed light on excitation energy transfer from PBS to PSII.

A novel approach for the router nodes placement in wireless mesh networks using phasing with approximation optimization algorithms

Optimal router node placement (RNP) is an effective method for improving the performance of wireless mesh networks (WMN). However, solving the RNP problem in WMN is difficult because it is NP-hard. As a result, this problem can only be solved using approximate optimization algorithms such as heuristics and meta-heuristics. In this study, we propose a new and effective method for solving the RNP problem. The idea behind this method is to solve the RNP problem in two stages using an optimal algorithm with fewer variables than the original RNP problem. In stage 1, we build an RNP sub problem using 15% to 20% of the number of routers, with the objective function of minimizing coverage overlap between routers to form a core network. Stage 2 is built into another RNP sub problem with the remaining number of routers, and the objective function is to maximize the network connectivity. Each sub problem was solved using an approximate optimal algorithm. The experimental results demonstrate that, in terms of client coverage and network connectivity, our proposed method outperforms widely used RNP problem-solving methods.

Spin-waves propagation along planar domain wall channels with perpendicular intersection

Spin-waves have been intensely investigated as a promising candidate for information carriers. The excitation and propagation of spin-waves along reconfigurable magnonic circuits are of much interest for the development of magnonic applications. In the present paper, the spin-wave propagation in a reconfigurable domain wall (DW) channel is investigated theoretically through micromagnetic simulations in the perpendicular ferromagnetic film. The non-linear propagation scheme with a perpendicular intersection linking the transverse and longitudinal DW channels is realized by using the coherent excitation without applying an external field. The intensity of spin-waves propagating along DW channels exhibits a significant enhancement compared to bulk-type spin-wave propagation and a nano-sized wavelength with the maximum phase velocity exceeding 2 km/s is achieved. Moreover, the DW-type spin-waves propagation presents close correlation with the Dzyaloshinskii–Moriya interaction and the shift angle of the pinning layer magnetization relative to wave vector, which will determine the feasibility of spin-wave propagation passing through the perpendicular intersection of DW channels under different input modes. Consequently, the available logic gates of and, or, and not A are proposed by tuning the shift angle along longitudinal DW, based on the three-terminals device with two transverse inputs and one longitudinal output.

Complement C3 of tumor-derived extracellular vesicles promotes metastasis of RCC via recruitment of immunosuppressive myeloid cells

Heterogeneous roles of complement C3 have been implicated in tumor metastasis and are highly context dependent. However, the underlying mechanisms linking C3 to tumor metastasis remain elusive in renal cell carcinoma (RCC). Here, we demonstrate that C3 of RCC cell-derived extracellular vesicles (EVs) contributes to metastasis via polarizing tumor-associated macrophages (TAMs) into the immunosuppressive phenotype and recruiting polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). Mechanistically, EV C3 induces the secretion of CCL2 and CXCL1 by lung macrophages and subsequently enhances TAM polarization and PMN-MDSC recruitment. Notably, targeting the CCL2/CCR2 or CXCL1/CXCR2 axis with the inhibitors RS504393 or Navarixin, respectively, effectively suppresses lung metastasis induced by RCC-derived C3 in a mouse model. Clinically, RCC patients with high expression of C3 demonstrate poor prognosis. Collectively, our findings reveal that tumor-derived EV C3 induces an immunosuppressive tumor microenvironment via TAMs, and thus promoting RCC metastasis.

Separation effectiveness of ideal ion exchange membranes: Application of the Gibbs-Donnan theory

Ion exchange membranes (IEMs) are permselective membranes that, in principle, only allow the flow of ions with a specific charge sign, opposite to that of the fixed membrane ionic groups (counter-ions). This charge-based selectivity, like the size-based selectivity of classic semipermeable membranes, leads to an uneven distribution of permeating ions on the two sides of the membrane, which allows for ion separation or recovery in various processes in industry or environmental protection. Here, we apply the principles of mass balance, charge neutrality, and equality of electrochemical potentials in the state of thermodynamic equilibrium to provide a simple method for estimating the Gibbs-Donnan factors and the equilibrium concentrations of permeating ions in two compartments separated by an ideal IEM, i.e. an IEM that is not permeable to co-ions. We present the method for the case when the equilibrium concentrations are known in one compartment and need to be estimated in the other compartment as well as for the case when the total masses of ions in both compartments are known and their equilibrium concentrations need to be predicted. For both cases, the presented nonlinear algebraic equations require in general the use of numerical methods to approximate their mathematical solutions, although we present as well some closed solutions for simple cases with ideal ionic mixtures. Based on the extended Debye–Hückel theory, we also provide analogous equations (general and for specific cases) for systems with non-ideal ionic mixtures. The presented method can provide the expected ideal separation effectiveness of an IEM, which can then be used to assess the relative separation effectiveness of a real membrane.

Broadband microwave emission from acoustically modulated gain-driven polaritons

By integrating a cantilever into a gain-embedded cavity magnonics platform, we investigate the impact of mechanical vibrations on gain-driven polaritons. The cantilever’s modulation creates a series of Floquet states spaced by the mechanical vibration energy, leading to microwave frequency comb emission centered at 3.5 GHz, with comb spacing as narrow as a few kilohertz. When the modulation frequency drops below 1 kHz, where the modulation period significantly exceeds the emission coherence time (360μs), quasienergy level overlap results in broadband microwave emission. The emission bandwidth is determined by the combined effects of mechanical modulation of the cavity and magnon–photon coupling (i.e., detuning). These results highlight the potential of acoustic-frequency modulation in a gain-driven polariton system to precisely control microwave emission characteristics.

Molecular mechanism of ligand recognition and activation of lysophosphatidic acid receptor LPAR6

Lysophosphatidic acid (LPA) exerts its physiological roles through the endothelialdifferentiation gene (EDG) family LPA receptors (LPAR1-3) or the non-EDG family LPA receptors (LPAR4-6). LPAR6 plays crucial roles in hair loss and cancer progression, yet its structural information is very limited. Here, we report the cryoelectron microscopy structure of LPA-bound human LPAR6 in complex with a mini G 13 or G q protein. These structures reveal a distinct ligand binding and recognition mode that differs significantly from that of LPAR1. Specifically, LPA uses its charged head to form an extensive polar interaction network with key polar residues on the extracellular side of transmembrane helix 5-6 and the extracellular loop 2. Structural comparisons and homology analysis suggest that the EDG and non-EDG families use two distinct modes for LPA binding. The structural observations are validated through functional mutagenesis studies. We further uncover the mechanisms of LPAR6 activation and principles of G-protein coupling. The structural information revealed by our study lays the groundwork for understanding LPAR6 signaling and provides a rational basis for designing compounds targeting LPAR6.

Pre-treatment subjective sleep quality as a predictive biomarker of tDCS effects in preclinical Alzheimer’s disease patients: Secondary analysis of a randomised clinical trial

Background Despite transcranial direct current stimulation (tDCS) has demonstrated encouraging potential for modulating the circadian rhythm, little is known about how well and sustainably tDCS might improve the subjective sleep quality in older adults. This study sought to determine how tDCS affected sleep quality and cognition, as well as how well pre-treatment sleep quality predicted tDCS effects on domain-specific cognitive functions in patients with mild neurocognitive disorder due to Alzheimer’s disease (NCD-AD). Methods This clinical trial aimed to compare the effectiveness of tDCS and cognitive training in mild NCD-AD patients (n =  201). Over the course of four weeks, patients were randomized to receive either tDCS plus working memory training, or sham tDCS plus working memory training, or tDCS plus controlled cognitive training. The Pittsburgh Sleep Quality Index (PSQI) was used to measured subjective sleep quality. The Alzheimer’s disease assessment scale-cognitive subscale (ADAS-Cog) was used to evaluate domain-specific cognitive functions. Results Recurrent tDCS treatments enhanced subjective sleep quality and cognition considerably. The poor sleepers (i.e., PSQI &gt;  5) who received tDCS treatment had more cognitive benefits (p =  0.031, Cohen’s d =  0.605) and sleep improvements (p &lt;  0.001, Cohen’s d =  1.209) in comparison to cognitive training. Pre-treatment subjective sleep quality was linked to tDCS-induced improvement in memory function. Conclusion During the course of two months, repeated tDCS could considerably enhance subjective sleep quality. For the cognitive benefits of the treatments, the status of pre-treatment subjective sleep quality is crucial. More thorough research is necessary to explore an efficient approach to managing comorbidities for preclinical AD patients.

Electrical conductivity of multilayered Cu/Nb composites fabricated by accumulative roll bonding

The electrical conductivity of nanolayered copper/niobium composites fabricated using accumulative roll bonding was investigated as a function of layer thickness. Cu/Nb was used as a model system to evaluate the processing-structure–property relationship stemming from the accumulative roll bonding process. The physical properties were compared against samples of individual average layer heights ranging from 193 to 25 nm. The electrical resistivity was measured over a temperature range of ∼3–300 K. Analysis on the role of interfaces on temperature dependence is conducted including the residual resistivity ratio and temperature coefficient of resistivity. It was found that electrical resistivity increases with decreasing layer height.

Microfluidic purification of genomic DNA

We describe a microfluidic device to extract DNA from a cell lysate, without the need for centrifuges, magnetic beads, or gels. Instead, separation is driven by transverse migration of DNA, which occurs when a polyelectrolyte solution flowing through a microfluidic channel is subjected to an electric field. The coupling of the weak shearing with the axial electric field is highly selective for long, flexible, charged molecules, of which DNA is the sole example in a typical cell lysate. As a result of migration to the walls, DNA is held near the channel inlet by electrophoresis (there is no flow near the channel walls), while the remaining components are eluted by the much larger (at least 10-fold) convective flow. We have demonstrated the feasibility of the device by recovering up to 40 ng of purified DNA in less than 30 min from 10 μ L of Escherichia coli lysate. Gel electrophoresis indicates minimal additional fragmentation during purification, up to the maximum length recorded by the gel (60 kbp). Electropherograms were also obtained for purified mammalian DNA, using a Femto Pulse system (fragment lengths up to 165 kbp). Extracted samples show strong amplification by PCR, while the original lysate does not. Mixtures of λ -DNA and BSA were used to determine the extent of the separation of DNA from a physiological concentration of proteins (30 mg/mL). The protein concentration in the extract (0.3 to 0.5 ng/µL) was reduced by five orders of magnitude from the initial mixture.

Correction: The shadow of the family: Historical roots of social trust in Europe

Chemical transport-based growth of Si and SiGe nanowires

This study investigates the chemical transport-based growth of Si and Ge nanowires (NWs) using plasma-enhanced chemical vapor deposition. We found that Si NW growth requires a high etching temperature of 400 °C, related to a stronger Si–H bond energy compared to the Ge–H bond energy, allowing Ge NWs to form at 250 °C. The growth process is influenced by various parameters, including etching temperature, radio frequency power, GeH4/SiH4 precursor gas ratios, doping, and inter-electrode distance. Optimal Si NW growth is achieved at a substrate temperature of 250 °C during pre-coating and 400 °C during etching, with an RF power of 100 W. Conversely, Ge NWs can be fabricated at 250 °C, although they tend to be smaller and less dense. The study also highlights the role of the doping of the amorphous film precursors, with n-type doping enhancing growth and crystallization, while p-type doping negatively affects NW formation. Key findings include the significance of maintaining optimal etching time and its effect on NW morphology and uniformity. Overall, the results provide a novel method for efficiently growing Si and Ge NWs, emphasizing the importance of carefully controlling growth conditions.

Metabolic activity controls the emergence of coherent flows in microbial suspensions

Photosynthetic microbes have evolved and successfully adapted to the ever-changing environmental conditions in complex microhabitats throughout almost all ecosystems on Earth. In the absence of light, they can sustain their biological functionalities through aerobic respiration, and even in anoxic conditions through anaerobic metabolic activity. For a suspension of photosynthetic microbes in an anaerobic environment, individual cellular motility is directly controlled by its photosynthetic activity, i.e. the intensity of the incident light absorbed by chlorophyll. The effects of the metabolic activity on the collective motility on the population level, however, remain elusive so far. Here, we demonstrate that at high light intensities, a suspension of photosynthetically active microbes exhibits a stable reverse sedimentation profile of the cell density due to the microbes’ natural bias to move against gravity. With decreasing photosynthetic activity, and therefore suppressed individual motility, the living suspension becomes unstable giving rise to coherent bioconvective flows. The collective motility is fully reversible and manifests as regular, three-dimensional plume structures, in which flow rates and cell distributions are directly controlled via the light intensity. The coherent flows emerge in the highly unfavorable condition of lacking both light and oxygen and, thus, might help the microbial collective to expand the exploration of their natural habitat in search for better survival conditions.