Frataxin is a mitochondrial iron-binding protein whose deficiency causes Friedreich's ataxia, yet the dynamic mechanisms by which this protein communicates iron-binding events to distal regions remain poorly understood. Traditional correlation-based analyses identify coupled residue motions but cannot resolve the directionality of information flow, leaving critical mechanistic gaps. Here we employ transfer entropy analysis of molecular dynamics simulations (1.5 μs) to map the complete allosteric network in human frataxin, validated through orthogonal experimental approaches. We identify LEU47 (LEU136 in UniProt Q16595 numbering) and LEU51 (LEU140) as primary signal sources with net transfer entropy values of 0.415 and 0.249, respectively, connecting the hydrophobic core to the iron-binding acidic ridge. NMR relaxation at 600 and 800 MHz reveals elevated R2/R1 ratios (9.90-10.00) and significant exchange contributions (Rex = 3-5 s-1) specifically at these primary signal source residues, indicating μs-ms dynamics. Hydrogen-deuterium exchange mass spectrometry demonstrates that hub residues possess intermediate protection factors (ln(PF) = 5.97-6.07) optimal for conformational signaling, while iron binding induces bidirectional protection changes propagating through the identified pathway. Systematic mutagenesis confirms that disruption of hub residues reduces iron-binding affinity 1.9-4.2-fold and decreases thermal stability by 4.3-11.2 °C, despite occupying buried-core positions distant from the iron-coordinating acidic-ridge residues (LEU136/LEU140 Cα to ASP122, ASP124, and GLU189 = 6.7 to 11.8 Å in PDB 1EKG). The strong prediction-experiment correlation establishes transfer entropy as a reliable predictor of functionally important allosteric residues and provides a methodological framework applicable to other proteins of biomedical significance.
Mg(II) and Cu(II) sources with decanedioic acid (DDA) were utilized for the preparation of diverse mechanically flexible self-repairing supramolecular metallogels, abbreviated as Mg-DMSO-DDA-DMSO, Mg-DMSO-DDA-DMF, and Cu-water-DDA-DMSO. The strategy of employing a low-molecular-weight gelator-guided supramolecular metallogel formation pathway has been executed. Diverse polar aprotic (such as DMSO and DMF) and protic (such as water) solvent media with pure and mixed polar environments are implemented for the formation of diverse metallogels. The diversity of mechanical flexibility with the exploration of rheoreversible properties with respect to the involvement of metal resources such as Mg(II) and Cu(II)-based systems along with gel-immobilized solvent media has been studied. The role of different metallogel-forming ingredients toward the networks of diverse metallogels was inspected through FESEM microscopy. The role of gel-forming elements was also explored through EDX elemental analyses. Stimuli-sensitive features, i.e., the influences of external impacts covering mechanical shaking, heating, chemical, and light sensitivity on diverse metallogels, have been critically studied. The metallogel-forming mechanistic pathways are also judged through the application of FT-IR-based experiments with gel states of different metallogels. The gel formation pathways for individual metallogels are also studied through the involvement of ESI-Mass-directed experimental protocols. Metallogels have also been characterized through powder X-ray diffraction studies, thermogravimetric analyses, UV-Vis spectral analyses, and transmission electron microscopy (TEM) studies. Besides, the bioapplications of these metallogels are also studied using diverse pathogenic strains (i.e., two Gram-positive species (Listeria monocytogenes and Bacillus cereus) and two Gram-negative species (Escherichia coli and Salmonella typhimurium). Thus, this work will be an illustration of successfully achieving mechanically flexible self-repairing soft matter for potential biological uses.
It is shown that an efficient, "direct", and fully quantum mechanical calculation of thermal reaction rate coefficients requires a new, partially rearranged form of the numerically constructed exact kinetic energy part of the rovibrational Hamiltonian expressed in internal coordinates. Using this Hamiltonian and an accurate, full-dimensional potential energy surface characterizing the H2 + H exchange reaction, developed by Mielke, S. L.; et al.J. Chem. Phys.2002, 116, 4142-4161., reaction rate coefficients in the temperature range of 75-800 K have been computed for the H2 + D → HD + H reaction. The paper puts particular emphasis on the exact treatment of overall molecular rotation and on nuclear spin symmetry.
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Corticosteroids modulate key inflammatory and fibroproliferative pathways involved in ARDS through genomic and non-genomic glucocorticoid receptor signaling. Advances in ARDS pathophysiology have highlighted the importance of timing, inflammatory burden, and host response in determining treatment efficacy. Clinical evidence supports corticosteroid use in moderate-to-severe ARDS, particularly in COVID-19 ARDS and severe community-acquired pneumonia, with reductions in mortality and duration of mechanical ventilation. However, treatment effects remain heterogeneous across etiologies and biological subphenotypes. Recent identification of hyperinflammatory and hypoinflammatory ARDS phenotypes suggests that corticosteroid responsiveness is not uniform. Hyperinflammatory phenotypes and septic ARDS appear more likely to benefit, whereas evidence remains limited or conflicting in influenza-associated and non-septic ARDS. Long-term effects and adverse outcomes, including metabolic complications and ICU-acquired weakness, remain insufficiently characterized. Future research is increasingly focused on precision medicine approaches integrating biomarkers, adaptive platform trials, and phenotype-guided strategies. Emerging developments include lung-targeted corticosteroid delivery systems and selective glucocorticoid receptor modulators designed to improve efficacy while reducing systemic toxicity. Corticosteroids should therefore be considered a context-dependent therapy whose benefit is influenced by etiology, disease stage, inflammatory phenotype, and timing of administration.
Using finite-difference time-domain simulation, we demonstrate that if an absorbing nanoparticle (e.g., gold, approximately 20 nm in diameter) is positioned near an isolated intensity null in the autofocus plane, both in a two-dimensional and three-dimensional non-paraxial laser beam, the particle experiences a force of the order of femtonewtons, causing it to move back near the zero intensity. Along part of this trajectory, the force is negative and pulls the particle backward. The direction of the absorbing nanoparticle's rotation around the zero intensity is the same as the direction of the canonical energy flux vector. The absorbing nanoparticle is, as it were, captured by the energy flux and moves with it, in both the positive and negative directions.
This systematic review and meta-analysis evaluated the clinical efficacy of propolis-containing formulations (PCFs) in preventing dental caries (PROSPERO: CRD420251246707). This study adhered to the PRISMA 2020 guidelines. Systematic database searches were conducted (December 11, 2025) without language or date restrictions. Eligible studies were randomized clinical trials (RCTs) assessing PCFs (dentifrices, mouthwashes, tablets, etc.) for caries-related outcomes compared with negative control or chlorhexidine-containing formulations (CHX). Standardized mean differences (SMD) were calculated using random-effects models. Meta-analyses were conducted for the outcomes plaque index (PI) and microbial counts in saliva or biofilm (MC). RoB 2 tool and GRADE were used as quality assessment tools. Of 1,919 identified records, 45 studies were included. Direct caries-related outcomes (caries indices) were rarely assessed and unsuitable for meta-analysis. PCFs significantly reduced PI compared with negative control (SMD[95% CI]: -1.11 [-1.52, -0.70], p < 0.01) and showed no significant difference compared with CHX (0.46 [-0.04, 0.95], p = 0.07). Similar patterns were observed for MC (PFCs vs. negative control (-1.45 [-2.43, -0.48], p = 0.004; PFCs vs. CHX: 0.38 [-0.11, 0.87], p = 0.13). Certainty of evidence was very low due to high risk of bias, inconsistency and indirectness. Propolis-containing formulations may reduce plaque indices and oral microbial counts, suggesting a potential role in caries prevention. However, high-quality studies assessing direct caries outcomes are needed to properly address the research question. Propolis-containing formulations are widely available and well accepted by patients. Clinicians may consider them as adjuncts to oral biofilm control but the evidence directly supporting their clinical efficacy in caries prevention is still not well established.
Vibrational Feshbach resonances (VFRs) constitute fundamental doorway states governing electron attachment and vibrational autodetachment in molecular anions. However, their real-time dynamics has remained largely unexplored for valence-bound radical anions because the exceptionally small electron affinities of these species make direct time-resolved measurements experimentally challenging. Here we investigate the nitromethane anion (CH3NO2-), a prototypical valence-bound radical anion with an electron affinity of only ∼0.17 eV, using picosecond mid-infrared pump-probe photoelectron spectroscopy. Selective excitation of the symmetric CH3 stretching mode reveals a vibrational autodetachment lifetime of approximately 10 ps, determined directly using a depletion-based time-resolved photoelectron detection scheme. This time scale is orders of magnitude longer than expected for prompt vibrational electron emission, demonstrating that autodetachment is limited by intramolecular vibrational redistribution (IVR), which redistributes the initially localized vibrational energy before the system gains access to the electron-detachment continuum. Picosecond IR photoelectron spectra further reveal transient population transfer from the valence-bound anion to a dipole-bound state (DBS), providing direct evidence for reverse internal conversion induced by mode-selective vibrational excitation. These findings establish that VFRs in valence-bound radical anions are not merely precursors to electron emission but constitute dynamical gateways that partition excess-electron relaxation between autodetachment and reverse internal conversion. This mechanistic picture provides a unified framework for understanding electron-driven chemistry in weakly bound molecular anions.
Carotid artery stenting (CAS) and carotid endarterectomy (CEA) are established revascularization strategies for carotid stenosis, yet evidence comparing them in asymptomatic populations remains limited. The Carotid Revascularization Endarterectomy versus Stenting Trial-2 used a parallel-arm design and did not provide a direct head-to-head comparison of CAS vs CEA. This study evaluates real-world long-term outcomes of CAS compared directly with those of CEA in asymptomatic carotid stenosis. Adults with asymptomatic carotid stenosis undergoing CAS or CEA between January 2016 and December 2024 were identified from the TriNetX US Collaborative Network. Patients with previous ischemic stroke, TIA, hemorrhage, or posterior-circulation stenosis were excluded. Propensity score matching (1:1) on demographics, comorbidities, and baseline antithrombotic medications yielded 5415 patients per cohort. Primary outcomes were all-cause mortality and ischemic stroke at 5 years; secondary outcomes included intraparenchymal hemorrhage and major bleeding. Kaplan-Meier analyses with log-rank testing and Cox proportional hazards models were used, with outcomes assessed at 6 months, 1, 3, and 5 years. Ischemic stroke occurred in 10.0% of CAS vs 9.8% of CEA patients (cumulative probability 15.85% vs 14.07%; hazard ratio [HR] 1.179, 95% CI 1.045-1.329, P = .007). All-cause mortality was higher after CAS (21.70% vs 18.69%; HR 1.212, 95% CI 1.084-1.355, P = .001). Intraparenchymal hemorrhage was more frequent after CAS (2.11% vs 1.30%; HR 1.940, 95% CI 1.327-2.835, P < .001). Major bleeding rates were comparable (12.10% vs 11.88%; HR 1.130, P = .071). All standardized differences were <0.10 postmatching. In real-world practice, CAS for asymptomatic carotid stenosis was associated with modestly higher ischemic stroke, mortality, and intraparenchymal hemorrhage compared with CEA over 5 years, suggesting an association favoring CEA. Prospective studies are needed to establish definitive causal relationships.
Plants respond to environmental stress by integrating epigenetic regulation with reactive oxygen species (ROS) signaling. This review examines the bidirectional interactions between epigenetic mechanisms and ROS homeostasis in plant stress adaptation, with a particular emphasis on drought resistance. Four epigenetic mechanisms, including histone modifications, DNA methylation, chromatin remodeling, and non-coding RNAs, control the expression of ROS-related genes, while in turn, ROS also alter chromatin structure and DNA methylation patterns. We propose that these interactions take the form of dynamic regulatory networks rather than one-way pathways, where changes in DNA methyltransferases and demethylation factors via ROS create reversible epigenetic states. This bilateral regulation can establish self-strengthening circuits that are capable of providing immediate responses to recurring stress. However, there is still a significant lack of knowledge, including the inconsistent reproducibility of stress priming protocols in studies, the incomplete understanding of how global oxidative stress induces epigenetic changes at specific sites, and the limited capacity for transgenerational transmission of stress-induced modifications. We review the evidence for epigenetic memory in plant stress responses, distinguish recurring adaptive plasticity from random variation, and highlight key mechanistic research directions for developing seasonally resilient crops through targeted epigenetic strategies.
Ammonia (NH3) emerges as a promising carbon-free, sustainable fuel, but its integration into technical combustion processes requires accurate, spatially, and temporally resolved diagnostics, obtained through non-invasive techniques like rotational coherent anti-Stokes Raman scattering (RCARS). However, the lack of spectroscopic data for ammonia-containing gas mixtures hinders its integration into advanced RCARS spectral models for data evaluation. In this study, we experimentally investigated the broadening effect of NH3 on the N2 S-branch Raman linewidths using the picosecond time-resolved RCARS technique. Experiments were conducted on N2-NH3 binary mixtures containing up to 50% NH3, at atmospheric pressure and temperatures up to 870 K close to the ammonia-air autoignition temperature. The peak intensities of the rotational spectrum of NH3 are weak compared with the N2 peak intensity and its rotational coherences decay more rapidly than those of N2, limiting the direct application of NH3-based RCARS diagnostics in the presence of intense scatterers and complicating its linewidths determination. Nevertheless, NH3 was found to induce significant broadening of the N2 Raman lines, which must be quantified to avoid diagnostic errors in RCARS. The magnitude of the S-branch Raman linewidth, obtained from the coherence decay time constant, increases linearly with NH3 concentration, indicating a more efficient collisional energy transfer in N2-NH3 compared to N2-N2 collisions. This behavior enables direct determination of N2-NH3 broadening coefficients, providing key spectroscopic parameters for RCARS spectral modeling. We further demonstrate that the inclusion of the newly determined linewidth data for nitrogen thermometry prevents temperature errors from inaccurate linewidth approximations. Thus, the obtained N2-NH3 broadening coefficients provide the spectroscopic basis for extending RCARS thermometry and species diagnostics to ammonia-fueled combustion and reactive flow environments.
Boreal forest ecosystems constitute a large terrestrial reservoir of carbon. In these nitrogen-limited environments, release of nutrients through decomposition of soil organic matter is of fundamental importance. Fungi, particularly saprotrophic Agaricomycetes, are thought to drive this process using lignocellulolytic enzymes to degrade plant litter. However, some ectomycorrhizal fungal lineages have retained ancestral decomposition capabilities, yet evidence of their direct involvement in decomposition under field conditions is scarce. We used metatranscriptomics to examine the involvement of ectomycorrhizal fungi in the production of class II peroxidases in the soil of a Swedish boreal forest. We compared nutrient-poor plots with more fertile ones and related the peroxidase-expressing community to the total and cellulose-degrading fungal communities. We found that overall expression of class II peroxidase genes was upregulated in nutrient-poor soil, with ectomycorrhizal species in the Cortinariaceae family accounting for most of the transcripts. Among cellulose-degrading fungi, there was a shift from saprotrophic Agaricomycetes in nutrient-rich soil to dominance by Ascomycetes under nutrient-poor conditions. Symbiosis may enable ectomycorrhizal fungi to use tree photoassimilates to drive energetically costly oxidation belowground. Ectomycorrhiza-driven oxidation may, thereby, enable trees to indirectly regulate decomposition and nutrient cycling to maintain ecosystem productivity on unfertile soils.
ObjectiveHematological involvement is a common manifestation of juvenile-onset systemic lupus erythematosus (jSLE). While nephrological and neurological involvement often guide treatment decisions in the early disease course, hematological findings may also impact morbidity and mortality. The aim of this study is to evaluate the clinical characteristics and treatment approaches of jSLE patients with hematological involvement.MethodThis retrospective, single-center cohort study was conducted on patients diagnosed with jSLE who were followed up at the pediatric rheumatology clinic between January 2015 and May 2025. Patients included in the study had been diagnosed with jSLE according to the 2012 Systemic Lupus International Collaborating Clinics classification criteria.ResultsThe study included 53 SLE patients, 48 of whom (90.6%) were female. The median age at diagnosis was 13 years (IQR: 11-15), and the median follow-up period was 26 months (IQR: 12-48). Hematological involvement was detected in 28 patients (52.8%). Anemia was observed in 18 (64.3%) of 28 patients, followed by lymphopenia in 16 (57.1%), thrombocytopenia in 14 (50.0%), and pancytopenia in 4 (14.3%). The median time to improvement of cytopenia following treatment was 32 days (IQR: 27-61). In 11 patients, treatment was based on isolated hematological findings, whereas in 17 patients with additional major organ involvement, treatment was mainly directed by the major organ manifestations. The frequency of constitutional symptoms, hypocomplementemia, and direct Coombs positivity were found to be significantly higher in patients with hematological involvement (p = 0.003, p = 0.034, p = 0.039, respectively). Intravenous ımmunoglobulin (IVIG) was also found to be administered more frequently in patients with hematological involvement (p = 0.010).ConclusionHematological involvement was detected in approximately half of jSLE patients. Hypocomplementemia and positive Coombs test were more frequently observed in patients with hematological involvement. The use of IVIG was also more common in patients with hematological involvement, and individualized treatment options remain important in the management of the disease.
Many child mass trauma interventions are a composite of multiple practice elements which commonly are not well identified or assessed in the treatment outcome research. Understanding the practice elements used for targeted (samples of children with direct exposure, intense experiences, and/or serious reactions) and universal (general samples without consideration of exposure or reactions) populations can help clarify future directions for intervention development and delivery. A systematic review of 84 randomized controlled trials (RCTs) and cluster RCTs identified 131 psychosocial interventions addressing mass trauma. The current analysis compared frequently used elements delivered to targeted and universal populations and examined the populations served across context (country income), event types (including the COVID-19 epidemic), delivery modes, and delivery settings. Reflecting the importance of accessible interventions for those with the greatest need, most child mass trauma interventions overall were administered to targeted populations in group applications delivered in schools or other community settings. Psychoeducation for the child, affect modulation, and relaxation were the most frequently offered elements for both targeted and universal populations. Exposure, narrative, and psychoeducation for the caregiver were administered more often in targeted than universal populations while social skills training, mindfulness, self-praise, and communication skills training were administered more often in universal populations. Future evaluation research should identify, describe, and evaluate specific practice elements included in interventions in the two populations and should address concerns related to certain groups of children receiving interventions and to aspects of intervention delivery.
This paper presents a Mach-Zehnder interferometer (MZI)-based vector bending sensor employing a four-core fiber and experimentally demonstrates its sensing performance. The sensor is fabricated by fusion splicing 1 mm long multimode fiber (MMF) segments to both ends of the four-core fiber, forming an interferometric structure with a well-defined resonance dip for curvature measurement. Due to the asymmetric arrangement of the fiber cores, the effective refractive index distribution changes with the bending orientation, thereby enabling vector bending sensing. Experimental results demonstrate that, within the curvature range of 0.497-0.642m-1, the maximum bending sensitivities along the two principal sensing axes reach 91.342 and 78.716nm/m-1, respectively, while the corresponding minimum sensitivities are 19.290 and 21.218nm/m-1. The sensor exhibits minimum sensitivity when the bending direction is perpendicular to the core-array axis and maximum sensitivity when it is parallel to the core-array axis. As the bending orientation varies from 0° to 360°, the sensitivity exhibits a periodic angular response. In addition, the temperature sensitivity of the sensor is measured to be 0.077 nm/°C. The proposed sensor features a simple fabrication process, good directional discrimination capability, and good repeatability, making it a promising candidate for vector bending sensing applications.
Magnetic resonance imaging (MRI)-guided endovascular interventions represent a radiation-free alternative to x-ray fluoroscopy but remain limited by the lack of compatible and visible instruments. This study aimed to characterise a balloon catheter with polymer-embedded superparamagnetic iron oxide nanoparticles (SPIONs) as a passive MR-visible marker. The SPION balloons consisted of a polymer with integrated iron oxide particles. A custom-built phantom study was conducted on a clinical 3-T MRI scanner using a balanced steady-state free precession sequence. Parameters influencing the balloons' imaging properties were evaluated: SPION content (5 weight percent (wt%), 20 wt% and 30 wt%), flip angle (10° to 60°), the balloons' spatial orientation relative to the main magnetic field B0, the inflation state and phase-encoding direction across different spatial orientations. The SPION-induced susceptibility artefacts were quantified from segmentations independently performed by two board-certified radiologists. All SPION-polymer balloons were discernible at 3-T MRI across all tested SPION concentrations. No linear correlation was observed between SPION concentration and artefact dimension, with the intermediate concentration of 20 wt% yielding the smallest artefact size. The balloons' artefact dimensions increased with higher angulations relative to B0. Balloons were visualised in the inflated and deflated configurations. The flip angle had a limited impact on artefact dimensions, while higher flip angles resulted in increased SNR. The influence of phase-encoding direction was generally minor with a single exception (90° coronal plane, AP to RL). The SPION-polymer balloons were effectively visualised at 3-T MRI irrespective of orientation and inflation. This in vitro study outlines a proof-of-concept supporting future clinical use of polymer-integrated SPIONs for passive device visualisation in interventional MRI. SPION-polymer balloons can be visualised in 3-T MRI, providing a foundation for future MRI-visible interventional instrument designs. Visualisation properties of a SPION-polymer balloon catheter were systematically assessed at 3-T MRI to overcome the shortage of MRI-visible instruments. SPION-polymer balloons were effectively visualised across different spatial orientations in the inflated and deflated state. Polymer-integrated SPIONs demonstrate potential as passive instrument markers for MRI-guided interventions.
Expressway fire incidents are rising, yet dedicated fire stations remain largely absent, forcing reliance on urban services ill-suited to the linear, directional topology of expressways. Existing urban-oriented location models, assuming static travel times and uniform fire risk, fail to capture dynamic congestion and heterogeneous risk profiles in such confined environments. This study develops an optimization framework for expressway fire station siting that integrates dynamic traffic conditions and segment-level risk heterogeneity to minimize response delays and improve post-crash rescue accessibility. In a case study of the Liuyang section of Hangchang Expressway, 1,495 demand points at 150-meter intervals and 10 candidate sites were identified. Fire rescue demand was quantified by combining dynamic travel times from the Baidu Maps API (24 daily intervals) and expert-assigned risk weights for tunnels, ramps, service areas, and general segments. A mixed-integer linear programming model maximized rescue demand satisfaction under constraints on station quantity (N = 1-6) and budget, with layouts solved via a branch-and-bound algorithm and evaluated using 10-minute response coverage as the primary indicator. With only existing urban stations (N = 0), no demand points (0%) were accessible within 10 min, most exceeding 30 min. Increasing new stations from 1 to 5 improved 10-minute coverage by 36.22 percentage points and reduced >30-minute points by 11.17 percentage points; marginal gains diminished beyond N = 5. Under a CNY 10 million budget, sites 6 and 7 were deployed, while CNY 20 million favored sites 4, 6, 7, and 8, achieving 39.26% coverage. With N = 3, a CNY 2.5 million budget increase shifted optimal sites from {2, 4, 7} to {4, 6, 7}, narrowing 20-30-minute response segments. Persistent > 30-minute gaps near certain interchanges stemmed from extended U-turn distances due to directional constraints. Static, urban-centric layouts are inadequate for expressways, leaving critical coverage gaps. The proposed framework integrates dynamic traffic conditions and heterogeneous risks, enabling resource-efficient siting. For the Liuyang corridor, five optimally sited stations offered the most cost-effective balance. This methodology provides a decision-support tool for authorities to rationalize emergency service layouts, expedite post-crash intervention, and enhance expressway safety.
Organic memristors have potential applications in simulating biological synapses for neuromorphic computing. In this work, a solution-processed Al/P3BT/indium tin oxide (ITO) organic memristor was designed. The device exhibits stable resistive switching behavior and successfully emulates versatile synaptic plasticity, including excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), spike-timing-dependent plasticity (STDP), the transition from short-term plasticity to long-term potentiation (STP-LTP), post-tetanic potentiation (PTP), and experiential learning. Fitting analyses of the I-V curves reveal that the resistive switching resulted from a combined contribution of direct tunneling, space-charge-limited conduction, Schottky emission, and Fowler-Nordheim tunneling. Moreover, the analog resistive switching behavior remains stable, even after exposure to ambient air for over 300 days. To exploit the nonlinear mappings through simple 3-bit pulse sequences, the constructed reservoir computing system achieves a recognition accuracy of 97.69% on the Modified National Institute of Standards and Technology (MNIST) handwritten digit classification task after only 20 training epochs, significantly outperforming conventionally trained network models. Furthermore, the system attains an accuracy of 87.02% on the Fashion-MNIST data set. This study provides valuable insights and perspectives on the emulation of artificial synaptic plasticity by using organic memristors and their application in neuromorphic computing.
Hydrophobic hydration underpins processes central to chemistry, biology, and technology, from protein folding and molecular self-assembly to catalysis and nanomaterial dispersion. However, direct structural information on water surrounding large hydrophobic molecules remains scarce due to their very low solubility. Here, we overcome this limitation by using low-temperature vapor codeposition to form amorphous mixtures of water and anthracene, a hydrophobic "mini-graphene". We then resolve the structure of anthracene's first hydration shell by neutron diffraction. The linear polycyclic aromatic hydrocarbon induces distinct structural motifs in its hydration shell. Water molecules above and below the outer aromatic rings exhibit one broken water-water hydrogen bond enabling weak O-H···π interactions with the solute, while a pronounced "dewetting" effect emerges at the central ring. These findings provide experimentally constrained structural insights into the hydration around a large hydrophobe under conditions where conventional liquid-state experiments are not feasible.
The preparation of semiconductor surfaces for renewable energy or other optoelectronic applications requires highly precise control of surface structure and composition, rendering vacuum-based techniques typically the method of choice. However, when precise process control is guaranteed, wet-chemical etching processes constitute a resource-efficient and scalable alternative. In this work, we show that reflection anisotropy spectroscopy (RAS)─a nondestructive, optical technique─offers a powerful in situ control of wet-chemical etching processes. Here, we employ RAS to determine the etching depth, rate, and time during the wet-chemical preparation of a photoelectrode for direct solar water splitting. This is achieved by observing and evaluating Fabry-Pérot-type oscillations of reflectance and RAS transients during the etching process. The occurrence of these oscillations confirms the uniform character of the investigated surface in a suitable etching parameter space and allows the determination of the etching depth with a precision of ±8 nm. A variation of the etching procedure demonstrates that RAS control can be used for the development of suitable etching routines and for in situ process control, as validated for two different types of photoelectrodes.