Strong Contrast Research Articles

Possible physical mechanisms of the high echogenicity of lipid coated nanobubbles

Lipid coated nanobubbles (NBs) have attracted a great level of interest as ultrasound (US) contrast agents due to their ability to extravagate through leaky tumor vasculature. Their linear resonance frequency is in the range of ∼50 M Hz–200 MHz, leading to confusion over their observed strong contrast in diagnostic US frequencies. By solving the Marmottant model, the dynamics of uncoated and lipid coated NBs and microbubbles (MBs) are studied over the frequency and pressure ranges (6–12 MHz, 0.1–1.2 MPa) generally used in diagnostic US. A novel bifurcation analysis in tandem with the analysis of the frequency component of the scattered pressure are conducted. Results show that despite the increased linear resonance frequency and viscous damping due to the lipid shell, buckling and rupture of the shell enhances the generation of the 2nd and 3rd harmonic resonances at pressures as low as 0.2 MPa, not observed with uncoated NBs. The generation of the harmonic resonances are concomitant with an abrupt increase in the 2nd and 3rd harmonic frequency component of the scattered pressure with their pressure threshold (PT) increasing with decreasing NBs size. For the same gas volume, and above the PT, the maximum non-destructive 2nd and 3rd harmonic powers of NBs can become higher than the 2–4 μm MBs. Similar to the lower subharmonic pressure threshold of MBs, the dynamic variation of the NBs effective surface tension due to buckling and rupture may be the potential reason behind the observed harmonic echogenicity.

CASE REPORT : OLFACTORY GROOVE MENINGIOMA

Abstract
 Background: Olfactory Groove Meningiomas (OGM) are a rare cause of olfactory dysfunction. OGMs are benign, slow-growing tumors that cause non-specific symptoms, such as headaches, olfactory impairment, and psychiatric symptoms, such as depression, personality changes, decreased cognitive function, visual problems, or seizures.
 Aim: In this case report we would like to discuss about a rare case of olfactory groove meningioma with non-spesific symptoms presented in 47-year old female patient
 Case report: A 47-year old female with progressive blurred vision in the right eye for 3 months. Negative light perception in the right eye and fundus of the right eye indicated papillary atrophy. The direct and indirect light reflexes were negative in the right eye. We found Strong homogenous contrast enhancement extraaxial lesion accompanied by multiple dural tails in the left frontal convexity UK approximately 3.2 x 2.8 x 3.1 cm, Tuberculum sellae approximately 2.7 x 2.9 x 3 cm. Cranial decompression, frontal bone reconstruction, and tumor removal were performed. It was found that there was microcystic growth of tumor tissue, consisting of proliferation of meningoethelial cells, round to oval nuclei, smooth chromatin, visible intranuclear inclusions
 Discussion: OGM is a rare, benign tumor. Female patients were more likely to develop OGM than male patients. The ciliary ganglion of cranial nerve III may be affected by compression of the tumor, resulting in the absence of direct and indirect pupillary reflexes in the affected eyes.
 Conclusion: OGM is a slow-growing tumor that does not show significant symptoms at an early stage, making early detection difficult.
 Keyword: Olfactory Groove Meningioma, Blurred Vision, Meningioma

Complex erosional response to uplift and rock strength contrasts in transient river systems crossing an active normal fault revealed by 10Be and 26Al cosmogenic nuclide analyses

AbstractUnderstanding the influence of bedrock lithology on the catchment‐averaged erosion rates of normal fault‐bounded catchments and the effect that different bedrock erodibilties have on the evolution of transient fluvial geomorphology remain major challenges. To investigate this problem, we collected 18 samples for 10Be and 26Al cosmogenic nuclide analysis to determine catchment‐averaged erosion rates along the well‐constrained Gediz Fault system in western Türkiye, which is experiencing fault‐driven river incision owing to a linkage event ~0.8 Ma and has weak rocks overlying strong rocks in the footwall. Combined with existing cosmogenic data, we show that the background rate of erosion of the pre‐incision landscape can be constrained as <92 mMyr−1, and erosion rates within the transient reach vary from 16 to 1330 mMyr−1. Erosion rates weakly scale with unit stream power, steepness index and slip rate on the bounding fault, although erosion rates are an order of magnitude lower than slip rates. However, there are no clear relationships between erosion rate and relief or catchment slope. Bedrock strength is assessed using Schmidt hammer rebound and Selby Rock Mass Strength Assessments; despite a 30‐fold difference in erodibility, there is no difference in the erosion rate between strong and weak rocks. We argue that, for the Gediz Graben, the strong lithological contrast affects the ability of the river to erode the bed, resulting in a complex erosional response to uplift along the graben boundary fault. Weak covariant trends between erosion rates and various topographic factors potentially result from incomplete sediment mixing or pre‐existing topographic inheritance. These findings indicate that the erosional response to uplift along an active normal fault is a complex response to multiple drivers that vary spatially and temporally.

Sentinel lymph node biopsy with carbon dye in endometrial cancer: a single center, prospective cohort study.

Many agents have been used for the detection of sentinel lymph nodes in endometrial cancer. Carbon dye, which has a strong staining ability and high contrast due to its dark black color, identifies the lymph nodes efficiently. Our aim was to evaluate the safety and efficacy of carbon dye for the detection of sentinel lymph nodes in endometrial cancer. We conducted a single-center, prospective, cohort study in 89 patients with early-stage endometrial cancer between September 2021 and August 2022. The procedure was performed under laparoscopy. The sensitivity and negative predictive value of the sentinel lymph node biopsy (SLNB) with carbon dye injection were 83.3% and 98.8%, respectively. Mapping identified at least one sentinel lymph node in 84 patients (94.4%) on one pelvic side and at least one sentinel lymph node in 73 patients (82.0%) on each pelvic side out of 89 patients. In addition, no carbon dye-associated allergic reaction was detected. Carbon dye is a non-allergenic, inexpensive, and effective agent for SLNB with a satisfying sensitivity and a negative predictive value. In addition, both unilateral and bilateral detection rates were sufficient. Accordingly, carbon dye may be a promising tracer and a considerable option, particularly for low-income countries.

Existence and bifurcation of positive solutions to a class of predator-prey models with mutual interference among the predators

In this work, we study a class of diffusive predator-prey models with mutual interference among the predators while searching for food. Under Dirichlet boundary condition, by the fixed point index theory, we provide the necessary and sufficient conditions for the existence of coexistence states (i.e., stationary pattern). This is a strong contrast to the corresponding Neumann boundary problem, which exhibits bistability and admits no patterns.

Control of Cardiac Biomarkers Concentrations, Central Hemodynamics and Their Correlation During Gastrointestinal Bleeding

We did not observe high values of cardiac markers and changes in central hemodynamic parameters in patients with acute gastrointestinal bleeding (AGIB) and a correlation between them, this led to the decision to conduct a study. Clinical materials of 457 patients diagnosed with GIB were analyzed. Cardiac pathology was detected in 150 patients. Dynamic changes in cardiac biomarkers and central hemodynamic indicators in patients were studied in 3 stages. Phase I, period included in ICU; Stage II - 24 hours after admission to the ICU; the third stage covers the next 48 hours. The concentration troponin, BNP, myoglobin and CK-Mb was studied in the patients and it was found that although the concentration of these biomarkers was high in the first stage, these concentrations decreased and reached normal levels in the later stages of the dynamics against the background of the treatment. Dynamic changes of central hemodynamic indicators (CHI): stroke volume, cardiac minute volume, peripheral vascular resistance and myocardial oxygen demand were studied in 3 stages. It was found that although SV was low, it dynamically increased in the later stages and did not reach the normal level. This is a clear example of continued hypovolemia. Peripheral vascular resistance (PVR) from blood loss from the gastrointestinal tract was greater than normal in all three phases. PVR remained high and was statistically honest because the volume of circulating blood was not fully corrected despite the treatments. Also, the correlation between central hemodynamic indicators and cardiac markers was studied, showing that in stage I, there is a strong contrast between CMV and CK-MB; Strong straight between PVR and BNP; In stage II, strong contrast between CMV and BNP; Strongly flat between PVR and CK-MB; In stage III, the average level is between CMV and myoglobin; We proved that there is a moderate inverse correlation between PVR and cTn and it is statistically honest. Thus, although CHI was slightly less than the norm in the initial period, it normalized in the later stages, but PVR remained high in all stages. This caused a sharp increase in PVR as a compensatory response to the decrease in circulating blood volume during acute GIB. Among the cardiac markers, we associate the rise of troponin during the bleeding period with damage to postanemic, hypoxic myocardial muscles. Among the cardiac markers, a sharp increase in BNP is an indicator of the development of left ventricular failure and is associated with a sharp increase in PVR, and we also proved that there is a strong direct relationship between them.

Analysing the commercial effects of animation’s aesthetic pictures: A case study on Coco

The advancement of technology in the field of visual imaging has led to a proliferation of animated films, which in turn has led to advancements in the field of visual communication. Additionally, audiences are more inclined to watch animated films that are attractive to the eye. However, there is a lack of study that applies the aesthetics of pictures to examine the effects that animation has on the marketplace. The purpose of the paper was to examine Coco’s economic accomplishments in terms of three visual aesthetic dimensions: the use of colour, the use of camera language, and the design of the characters. Therefore, developing an in-depth understanding of the superiorities that form the foundation of aesthetic theories provides helpful ideas. According to the findings of the thesis, Coco’s commercial success may be attributed, at least in part, to the film’s use of colours with strong contrast and saturation, interchangeable footage and exquisite compositions, and compatible and nationalized character designs. All of these factors contributed to the film’s popularity. After that, the research offers some related suggestions to upcoming animation producers, covering all aspects of the industry.

Do color enhancement algorithms improve the experience of color-deficient people? An empirical study based on smartphones.

Approximately 8% of the global population experiences color-vision deficiency. It is important to note that "color-vision deficiency" is distinct from "color blindness," as used in this article, which refers to the difficulty in distinguishing certain shades of color. This study explores color enhancement algorithms based on the neural mechanisms of color blindness and color deficiency. The algorithms are then applied to smartphones to improve the user experience (UX) of color-enhancing features in different top-selling smartphone brands with different operating systems (OS). A color-enhancing application program was developed for individuals with color-vision deficiency and compared to two other mature color-enhancing programs found in top-selling smartphones with different mainstream operating systems. The study included both objective and subjective evaluations. The research materials covered three aspects: daily life, information visualization, and videos. Additionally, this research study examines various levels of color enhancement through three dimensions of subjective evaluation: color contrast, color naturalness, and color preference. The results indicate that all color-enhancing features are beneficial for individuals with color-vision deficiencies due to their strong color contrast. The users' color preference is closely linked to color naturalness. The application program preserves the naturalness of colors better than the other two color-enhancing features. The subjective evaluations show similar trends across different operating systems, with differences arising from the use of different color-enhancing algorithms. Therefore, different algorithms may result in different sizes of the color gamut.

Association study between SNP markers located in meat quality candidate genes with intramuscular fat content in an endangered dual-purpose cattle population.

The aim of this study was to associate single nucleotide polymorphisms (SNP) of the bovine calcium-activated neutral protease µ-calpain, calpastatin, diacylglycerol-O-acyltransferase, adipose fatty acid binding protein, retinoic acid receptor-related orphan receptor C (RORC), and thyroglobulin (TG) gene with intramuscular fat content (IMF). Therefore, 542 animals of the cattle breed "Rotes Höhenvieh" (RHV) were phenotyped for IMF. Genotyping of the animals was performed using polymerase chain reaction-restriction fragment length polymorphism tests for six SNP from candidate genes for meat quality traits. In addition, we calculated allele substitution and dominance effects on IMF. A subgroup of animals (n = 44, reduced dataset) with extraordinary high IMF was analyzed separately. The mean IMF content was 2.5% (SD: 2.8) but ranged from 0.02% to 23.9%, underlining the breeds' potential for quality meat production. Allele and genotype frequencies for all SNP were similar in the complete and reduced dataset. Association analyses in the complete dataset revealed the strongest effects of RORC on IMF (P = 0.075). The log-transformed least-squares mean for IMF of genotype g.3290GG was 0.45 ± 0.16, 0.26 ± 0.14 for genotype g.3290GT, and 0.32 ± 0.14 for genotype g.3290TT. In the reduced dataset, we found a significant effect (P < 0.05) of the g.422C>T-SNP of TG on IMF, with highest IMF for genotype CT (0.91 ± 0.17), lowest IMF for genotype TT (0.37 ± 0.25), and medium IMF for genotype CC (0.59 ± 0.16; log-transformed values). Compared to the complete dataset, allele substitution effects increased in the reduced dataset for most of the SNP, possibly due to the selective genotyping strategy, with focus on animals with highest IMF implying strong phenotypic IMF contrast. Dominance effects were small in both datasets, related to the high heritability of IMF. Results indicated RHV breed particularities regarding the effects of meat quality genes on IMF. An explanation might be the breeding history of RHV with focus on adaptation and resilience in harsh outdoor systems. Consequently, it is imperative to develop breed-specific selection strategies. Allele substitution and dominance effects were in a similar direction in both datasets, suggesting the same breeding approaches for different RHV strains in different regions. Nevertheless, a selective genotyping approach (reduced dataset), contributed to more pronounced genotype effect differences on IMF and dominance values.

Hybrid ultrasound and photoacoustic contrast agent designs combining metal phthalocyanines and PBCA microbubbles.

Photoacoustic (PA) imaging is an emerging diagnostic technology that combines the penetration depth of ultrasound (US) imaging and the contrast resolution of optical imaging. Although PA imaging can visualize several endogenous chromophores to obtain clinically-relevant information, multiple applications require the administration of external contrast agents. Metal phthalocyanines have strong PA properties and chemical stability, but their extreme hydrophobicity requires their encapsulation in delivery systems for biomedical applications. Hence, we developed hybrid US/PA contrast agents by encapsulating metal phthalocyanines in poly(butyl cyanoacrylate) microbubbles (PBCA MB), which display acoustic response and ability to efficiently load hydrophobic drugs. Six different metal chromophores were loaded in PBCA MB, showing greater encapsulation efficiency with higher chromophore hydrophobicity. Notably, while the US response of the MB was unaffected by the loading of the chromophores, the PA characteristics varied greatly. Among the different formulations, MB loaded with zinc and cobalt naphthalocyanines showed the strongest PA contrast, as a result of high encapsulation efficiencies and tunable optical properties. The strong US and PA contrast signals of the formulations were preserved in biological environment, as demonstrated by in vitro imaging in serum and whole blood, and ex vivo imaging in deceased mice. Taken together, these findings highlight the advantages of combining highly hydrophobic PA contrast agents and polymeric MB for the development of contrast agents for hybrid US/PA imaging, where different types of information (structural, functional, or potentially molecular) can be acquired by combining both imaging modalities.

Structure searches and superconductor discovery in XB2 (X = Sc, Ti, V, Cr, and Tc).

With extensive structure searches for XB2 (X = Sc, Ti, V, Cr, and Tc) under pressures up to 100 GPa, we uncovered that the crystal structures of these compounds with the lowest enthalpy have the same space group (P6/mmm) as MgB2 at ambient pressure. Among them, ScB2, TiB2 and VB2 are dynamically stable at ambient pressure, but they do not superconduct. CrB2 becomes dynamically stable at 108 GPa and shows superconductivity with a transition temperature (Tc) of 26.0 K. TcB2 is not dynamically stable until 9 GPa. At 20 GPa, it has a Tc of 23.5 K. Further calculations indicate that CrB2 and TcB2 are also thermodynamically stable, suggesting that it is highly likely that they can be synthesized successfully in the laboratory. We found that transition metal atoms (Cr/Tc) dominate soft phonon vibrations and make significant contributions to the electron-phonon coupling (EPC) and superconductivity in CrB2/TcB2, which is in strong contrast to the case of MgB2, where high-frequency B vibrations dominate the EPC and superconductivity. Our work enriches the understanding of superconductivity in transition metal borides.

Multi-Convergence-Angle Ptychography with Simultaneous Strong Contrast and High Resolution

Multi-Convergence-Angle Ptychography with Simultaneous Strong Contrast and High Resolution

Integrating Point Spread Function into Taxel-based Tactile Pattern Super Resolution.

The past decade has witnessed the development of tactile sensors, which have been increasingly considered as an essential equipment in robotics, especially the dexterous manipulation and collaborative human-robot interactions. There are two major types of tactile sensors, i.e., the vision-based and taxel-based sensors. The latter is capable of achieving lower integration complexity with existing robotic systems, but unable to provide high-resolution (HR) tactile information as that of the vision-based counterpart due to the manufacturing limitations. Therefore, we propose a novel tactile pattern super-resolution (SR) scheme for taxel-based sensors, which is a data-driven scheme enabling customized selection on the number of applied "tapping" actions to achieve improvable performance from single tapping SR (STSR) to the multi-tapping SR (MTSR). In addition, we develop a new dataset for the proposed tactile SR scheme. In order to obtain scalable resolutions (e.g. ×4, ×10, ×20, etc.) of ground-truth HR tactile patterns, we propose a novel tactile point spread function (PSF) scheme to generate HR tactile patterns by leveraging the low-resolution (LR) data gathered directly from the taxel-based sensor and the depth information of contact surfaces. This is in strong contrast to the conventional ground-truth generation approach with overlapped multi-sampling and registration strategy, which can only provide a fixed resolution. Experimental results confirm the efficiency of the proposed scheme.

Non-resonant inelastic X-ray scattering for discrimination of pigments.

Inelastic X-ray scattering (IXS) spectroscopy has been used in many fields of solid-state physics and theoretical chemistry as an accurate and quantitative probe of elementary excitations. We show that non-resonant IXS spectra in the energy loss range below 100 eV exhibit a strong contrast across a wide range of commercially available pigments, opening new routes for their discrimination. These signatures combine plasmonic transitions, collective excitations and low energy absorption edges. We have performed IXS to discriminate different artists' pigments within complex mixtures and to quantitatively determine rutile and anatase polymorphs of TiO2. The integration of experimental data on pigment powders with suitable ab initio simulations shows a precise fit of the spectroscopic data both in the position of the resonances and in their relative intensity.

Deep learning-powered biomedical photoacoustic imaging

Photoacoustic Imaging (PAI) is an emerging hybrid imaging modality that combines optical imaging and ultrasound imaging, offering advantages such as high resolution, strong contrast, and safety. Despite demonstrating superior imaging capabilities, PAI still has certain limitations in its clinical application, such as the trade-off between imaging depth and spatial resolution, and the need for further improvement in imaging speed. Deep Learning, as a novel machine learning technique, has gained significant attention for its ability to improve medical image data and has been widely applied in PAI in recent years to overcome these limitations. In this review, we first introduce the principles of photoacoustic imaging, followed by the development and applications of popular deep neural network structures such as U-Net and GAN networks. Furthermore, we comprehensively discuss the recent advancements in the application of deep learning in photoacoustic imaging. Finally, a summary and discussion are provided.

3D Progression of Dead Li on Graphite Electrodes during Extended Fast Charging

Long charging times of commercial lithium-ion batteries (LIBs) constitute one of the critical remaining bottlenecks in the widespread deployment of electric vehicles (EVs). Therefore, there is a global push towards extreme fast charging (XFC)1in 10–15 minutes for 80% of the pack capacity. However, existing LIBs cannot achieve these XFC goals without significant capacity fade during cycling over battery lifetime.2 One of the key XFC degradation mechanisms is “Li plating,” which occurs when Li metal forms on the graphite electrode due the liquid electrolyte and solid-phase (graphite) mass transport limitations and sluggish charge-transfer kinetics of the Li intercalation reaction.3 This is mostly attributed to the formation of dead Li,4 which is the irreversibly plated Li that has become electronically disconnected from the graphite electrode. Since dead Li constitutes most of the XFC-related capacity loss, it is extremely important to unravel the link between its morphological evolution/progression, and battery capacity fade during extended XFC cycling.In this work, we report non-destructive, in-situ three-dimensional (3D) characterization of dead Li on graphite electrodes in full-cell LIBs during extended XFC using high-resolution (pixel size: ~ 7.8 µm; effective spatial resolution: ~25-30 µm) neutron micro-computed tomography (µCT). Specifically, we imaged batteries in the discharged state at the following cycle numbers at 6C charging rate: 10, 25, 50, and 150 cycles. Neutron µCT is promising for in-situ 3D Li detection on graphite electrodes because it provides strong contrast between Li and C (~ 71.87: 5.55 barns5). To leverage high-resolution neutron µCT for this work, we designed a custom neutron-friendly LIB coin-cell that provided exceptional neutron transmission at the graphite-separator-electrolyte interface as well as standard XFC performance at 6C between 3.0 and 4.1 V. We performed these imaging experiments at the MARS (CG-1D) beamline6 at the High Flux Isotope Reactor, Oak Ridge National Laboratory.Our results reveal 3D evolution of dead Li morphology from isolated plated deposits on only one edge of the graphite electrode after 25 cycles at 6C charging, to increasingly mossy-like covering the entire circumference of the graphite electrode after 150 cycles. Based on our imaging data, we did not observe any dead Li after only 10 XFC cycles. However, we noticed that dead Li started to nucleate around a partial edge of the graphite electrode after 25 XFC cycles, and then grew to the other edges after 50 XFC cycles, eventually forming a complete ring after 150 XFC cycles. At 150 XFC cycles, we also observed the dead Li ring outgrowths away from the edges of the graphite electrode onto the separator. In the extended XFC-cycled samples, 50 and 150 XFC cycles, we found significant dried out salt deposits on the separator, spacers, spring, and casing, which may be due to other parasitic reactions occurring at increased XFC cycling. Lastly, we determined quantitative relationships between the amount of dead Li in 3D, XFC cycling number, and XFC-related capacity loss of the battery.In conclusion, this work contributed to the advanced understanding of the 3D progression of dead Li and its relationship with XFC-related capacity loss on graphite electrodes during extended XFC cycling. We believe insights from this work will help develop improved 3D graphite electrode architectures that will minimize Li plating during repeated XFC cycling in fast-charged LIBs.

Beyond ray optics absorption of light in CsPbBr3 perovskite nanowire arrays studied experimentally and with wave optics modelling

We study experimentally and with wave optics modelling the absorption of light in CsPbBr3 perovskite nanowire arrays fabricated into periodic pores of an anodized aluminum oxide matrix, for nanowire diameters from 30 to 360 nm. First, we find that all the light that couples into the array can be absorbed by the nanowires at sufficient nanowire length. This behavior is in strong contrast to the expectation from a ray-optics description of light where, for normally incident light, only the rays that hit the cross-section of the nanowires can be absorbed. In that case, the absorption in the sample would be limited to the area fill factor of nanowires in the hexagonal array, which ranges from 13% to 58% for the samples that we study. Second, we find that the absorption saturates already at a nanowire length of 1000–2000 nm, making these perovskite nanowires promising for absorption-based applications such as solar cells and photodetectors. The absorption shows a strong diameter dependence, but for all diameters the transmission is less than 24% already at a nanowire length of 500 nm. For some diameters, the absorption exceeds that of a calculated thin film with 100% coverage. Our analysis indicates that the strong absorption in these nanowires originates from light-trapping induced by the out-of-plane disorder due to random axial position of each nanowire within its pore in the matrix.

Conjugate heat transfer of a turbulent tube flow of water and GaInSn with azimuthally inhomogeneous heat flux

An experimental study of the conjugate heat transfer in a turbulent tube flow with azimuthally homogeneous and inhomogeneous heat flux distribution, where the tube is heated with a constant heat flux only over the half circumference, is presented. Using two fluids with clearly different Prandtl numbers (water and a liquid metal alloy), thermohydraulic effects that occur when fluids with very low Prandtl number are used in contrast to ordinary fluids (e.g. water with Pr≈1) are discussed. The test section is validated with water (Pr=5−7.4) for a Reynolds number in the range of 5·103<Re<4.2·104. The experimental data agree excellently with literature data. The maximum nondimensional temperature at the inner surface of the tube is expressed using a simple relationship based on the efficiency of a fin with an adiabatic tip. A near eutectic alloy of gallium, indium and tin (GaInSn, Pr=0.03) is used for the liquid metal experiments. The Péclet number is varied within the range of 240<Pe<3·103. Based on the experimental data of this work, an adapted correlation for the Nusselt number in a turbulent liquid metal tube flow with azimuthally homogeneous heat flux is provided:Nu=4.364+0.0276·Pe0.803The experimental data underlines, that the azimuthally averaged Nusselt number for an azimuthally inhomogeneous heat flux distribution can also be calculated with this correlation with an acceptable level of accuracy. Remarkably, the ratio of the local convective heat transfer coefficient to the azimuthally averaged value for GaInSn reaches a value up to 0.6 at the location of the maximum wall temperature. This is in strong contrast to water, where this ratio is close to unity.

Single-Molecule X-ray Scattering Used to Visualize the Conformation Distribution of Biological Molecules via Single-Object Scattering Sampling.

Biological macromolecules, the fundamental building blocks of life, exhibit dynamic structures in their natural environment. Traditional structure determination techniques often oversimplify these multifarious conformational spectra by capturing only ensemble- and time-averaged molecular structures. Addressing this gap, in this work, we extend the application of the single-object scattering sampling (SOSS) method to diverse biological molecules, including RNAs and proteins. Our approach, referred to as "Bio-SOSS", leverages ultrashort X-ray pulses to capture instantaneous structures. In Bio-SOSS, we employ two gold nanoparticles (AuNPs) as labels, which provide strong contrast in the X-ray scattering signal, to ensure precise distance determinations between labeled sites. We generated hypothetical Bio-SOSS images for RNAs, proteins, and an RNA-protein complex, each labeled with two AuNPs at specified positions. Subsequently, to validate the accuracy of Bio-SOSS, we extracted distances between these nanoparticle labels from the images and compared them with the actual values used to generate the Bio-SOSS images. Specifically, for a representative RNA (1KXK), the standard deviation in distance discrepancies between molecular dynamics snapshots and Bio-SOSS retrievals was found to be optimally around 0.2 Å, typically within 1 Å under practical experimental conditions at state-of-the-art X-ray free-electron laser facilities. Furthermore, we conducted an in-depth analysis of how various experimental factors, such as AuNP size, X-ray properties, and detector geometry, influence the accuracy of Bio-SOSS. This comprehensive investigation highlights the practicality and potential of Bio-SOSS in accurately capturing the diverse conformation spectrum of biological macromolecules, paving the way for deeper insights into their dynamic natures.

Linking Water Age, Nitrate Export Regime, and Nitrate Isotope Biogeochemistry in a Tile‐Drained Agricultural Field

AbstractAccurately quantifying and predicting the reactive transport of nitrate () in hydrologic systems continues to be a challenge, due to the complex hydrological and biogeochemical interactions that underlie this transport. Recent advances related to time‐variant water age have led to a new method that probes water mixing and selection behaviors using StorAge Selection (SAS) functions. In this study, SAS functions were applied to investigate storage, water selection behaviors, and export regimes in a tile‐drained corn‐soybean field. The natural abundance stable nitrogen and oxygen isotopes of tile drainage were also measured to provide constraints on biogeochemical transformations. The SAS functions, calibrated using chloride measurements at tile drain outlets, revealed a strong young water preference during tile discharge generation. The use of a time‐variant SAS function for tile discharge generated unique water age dynamics that reveal an inverse storage effect driven by the activation of preferential flow paths and mechanically explain the observed variations in isotopes. Combining the water age estimates with isotope fingerprinting shed new light on export dynamics at the tile‐drain scale, where a large mixing volume and the lack of a strong vertical contrast in concentration resulted in chemostatic export regimes. For the first time, isotopes were embedded into a water age‐based transport model to model reactive transport under transient conditions. The results of this modeling study provided a proof‐of‐concept for the potential of coupling water age modeling with isotope analysis to elucidate the mechanisms driving reactive transport.