Magnification Factor Research Articles

Organophosphate ester flame retardants in sediments and marine fish species in Colombia: Occurrence, distribution, and implications for human risk assessment.

Exposure to organophosphate esters (OPEs) remains a significant concern, especially in aquatic systems where these compounds can bioaccumulate in organisms. However, limited information exists regarding their potential health risks to humans through the food web in tropical ecosystems. This study investigated the levels, bioaccumulation, and trophic transfer of OPEs in sediments and marine fish species from Cartagena and Barbacoas bays, Colombia. Twenty target OPEs were quantified in sediments and fish. The average concentrations of ∑18OPEs in sediments ranged from 2.80 to 115ng/g dry weight (dw), while ∑20OPE concentrations in fish ranged from 212 to 1968ng/g lipid weight (lw), with the highest concentrations found in carnivorous species. Trophic magnification factors (TMF) for OPEs varied from 11.0 to 25.8 for compounds such as 2-ethylhexyl diphenyl phosphate (EHDPP), 4-isopropylphenyl diphenyl phosphate (4IPPDPP), tris(2-isopropylphenyl) phosphate (T2IPPP), and tricresylphosphate (TCP), indicating their potential for biomagnification within the marine food web. Biota-sediment accumulation factors (BSAF) for ∑11OPEs ranged from 0.340 to 4.32, showing a significant Spearman correlation with log Kow in fish: Pargo chino (r=-0.78, p<0.05), Mojarra blanca (r=0.79, p<0.05), and Lisa (r=0.72, p<0.05). This suggests that bioaccumulation and biomagnification of certain OPEs in fish increase with the lipophilicity of these compounds. Despite these findings, the potential human health risk from OPE exposure via fish consumption was found to be minimal.

Guidance for measuring and evaluating biomagnification factors and trophic magnification factors of difficult substances: application to decabromodiphenylethane.

As field based trophic magnification factors (TMFs) and biomagnification factors (BMFs) become more prominent regulatory metrics used in bioaccumulation assessments of commercial chemicals, there is a need to develop standardized guidelines for conducting field-based bioaccumulation studies and to establish methods using weight of evidence analyses of those studies. Hence, the primary objectives of this study were (1) to compile a set of comprehensive criteria and guidelines for conducting field-based biomagnification studies and (2) to develop a weight of evidence meta-analysis for evaluating field-based biomagnification studies and their reported biomagnification metrics for assessing the biomagnification potential of substances. To test the effectiveness of our proposed guidelines and weight of evidence meta-analysis, we reviewed over 25 field studies investigating the biomagnification of decabromodiphenyl ethane (DBDPE), a substance that is considered super-hydrophobic and difficult to test in bioconcentration tests. Approximately half of the field studies that investigated trophic magnification of DBDPE in food webs or biomagnification of DBDPE in predator-prey interactions were considered of acceptable quality, whereas no studies were of high quality. Quality scores of studies statistically decreased with increasing TMF (r2 = 0.261, p = .035) and/or BMF (r2 = 0.238, p = .0024). The weight of evidence meta-analysis indicated with a high level of confidence that concentrations of DBDPE do not biomagnify in top predators and within food-webs. Given the increasing importance of the TMF and BMF for bioaccumulation assessments and the apparent deficiencies in current biomagnification studies identified in this meta-analysis for DBDPE, there is an urgent need to adopt standardized guidelines and procedures for both conducting and evaluating field-based biomagnification studies.

Bioaccumulation of novel brominated flame retardants in a marine food web: A comprehensive analysis of occurrence, trophic transfer, and interfering factors.

Although the concept of bioaccumulation for novel brominated flame retardants (NBFRs) is clear, the process and interfering factors of bioaccumulation are still not fully understood. The present study comprehensively evaluated the occurrence, transfer and interfering factors of NBFRs in a marine food web to provide new thought and perspective for the bioaccumulation of these compounds. The occurrence of 17 NBFRs were determined from 8 water, 8 sediment and 303 organism samples collected from Dalian Bay, China. The trophic magnification factor (TMF), the bioaccumulation factor (BAF) and the biota sediment accumulation factor (BSAF) were calculated in a plankton-mollusk-crustacean-fish based food webs. Results showed that among the 17 target NBFRs, 11 compounds appeared the significant trophic magnification and 2 compounds of decabromodiphenylethane (DBDPE) and octabromotrimethylphenylindane (OBIND) presented the significant trophic dilution. The significant positive correlation was found between the value of BAFs and the trophic level for 15 NBFRs (except DBDPE and OBIND), indicating that the species with high BAFs values were all at high trophic levels. The stable and rapid metabolic rates of DBDPE and OBIND constitute the main reason why they hardly accumulate in high trophic level organisms. The BSAFs of NBFRs in swimming organisms were much higher than that in mollusks and crustaceans, indicating that a large part of NBFRs accumulated from food webs. The significant positive correlation between TMF and BAF was observed in high trophic level organisms, which demonstrates the important role of high trophic level organisms in evaluating the bioaccumulation effect of NBFRs.

Pollution characteristics and risk assessment of organophosphate esters in mollusks along the coast of South China

Organophosphate esters (OPEs) are emerging pollutants and used extensively in industrial production as alternative to the traditional flame retardants. This study investigated the contamination characteristics and health risks of OPEs in 104 mollusks from 15 cities along the coastal region of South China. Σ8OPEs ranged from 48.2 to 1937 ng/g dw, with a mean value of 295 ng/g dw. TDCIPP, TCPP, and TCEP were the dominant OPEs. Different spatial distributions were observed, with higher concentrations in Guangdong Province. A statistically positive but non-significant linear correlation was found between the trophic level of mollusk and OPEs concentration. The trophic magnification factors were >1, suggesting that OPEs have the potential to biomagnify in mollusks. OPEs in mollusks pose low non-carcinogenic and carcinogenic risks to consumers. This study provides an important basis for managing the safety risks associated with OPEs in mollusks.

Global occurrence, food web transfer, and human health risks of polycyclic aromatic hydrocarbons in biota.

Polycyclic aromatic hydrocarbons (PAHs) are widespread organic pollutants that pose significant health risks due to their bioaccumulation in the biota. This study examines the global distribution of PAHs in biota, identifies key factors influencing using boosted regression tree (BRT) models, analyzes their transfer through trophic magnification factors (TMF), and evaluates health risks using the EPA risk assessment model. Research on PAHs has grown from 1978 to 2023, peaking in 2021, with 171 out of 241 studies (71.1%) focusing on marine ecosystems. The highest PAH concentrations are observed in the Mediterranean Sea, Red Sea, and North American coastal regions, primarily influenced by industrial and human activities, such as factory emissions and ship transport. BRT analysis shows region factors and feeding habitats significantly influence PAH levels. TMF analysis shows that biodilution is the main mechanism for PAH attenuation, with concentrations decreasing as trophic levels increase. Additionally, health risk assessment further illustrate that toxicity equivalent (TEQ) values are highest in Egypt and Turkey. Across all populations in Egypt, the United States, Turkey, Portugal, and China, as well as children in Portugal and Sweden, there are potential risks from aquatic product consumption (10-6<CRI<10-4), with CRI values positively correlated with liver cancer incidence. While hazard quotients (HQ)<1 suggest overall safety, higher obesity risks are noted, particularly among women and adolescents.

Trophic magnification rates of eighteen trace elements in freshwater food webs.

Trace elements play diverse roles in animal physiology ranging from essential micronutrients to potent toxicants. Despite animals accumulating many trace elements through their diets, relationships between trophic positions and biological concentrations of most trace elements remain poorly described. We report trophic transfer rates of Al, As, Ba, Cd, Co, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sr, Ti, Tl, U, V, and Zn from 31 freshwaters located in distinct biogeographic regions. Elemental concentrations and stable nitrogen isotope ratios (proxies for trophic position) were determined in zooplankton, molluscs, insects, and fishes from all sites. Trophic magnification factors (TMFs) were calculated as the mean fraction of each element that transferred from prey to predators at each site. TMFs >1 indicate biomagnification and TMFs <1 indicate biodilution. Mercury was the only biomagnifying element (median TMF=3.77), and selenium neither biomagnified nor biodiluted (median TMF=1.01). All 16 remaining elements biodiluted, with median TMFs ranging from 0.07 (uranium) to 0.60 (thallium). We used a model selection procedure to determine whether intrinsic physical and chemical elemental properties explained differences in TMFs among elements. Elements with high covalent bonding indices (Q) had marginally greater TMFs than elements with low Q values. Based on their high Q values, we recommend investigation into the trophic transfer rates of ten additional trace elements, some of which may biomagnify through some aquatic food webs. The high variability in TMFs within elements suggests that ecological factors are likely more important than intrinsic elemental properties at determining elemental TMFs.

Emerging and legacy organophosphate flame retardants in the tropical estuarine food web: Do they exhibit similar bioaccumulation patterns, trophic partitioning and dietary exposure?

Emerging organophosphate flame retardants (E-OPFRs) are a new class of pollutants that have attracted increasing attention, but their bioaccumulation patterns and trophodynamic behaviors in aquatic food webs still need to be validated by comparison with legacy OPFRs (L-OPFRs). In this study, we simultaneously investigated the bioaccumulation, trophic transfer, and dietary exposure of 8 E-OPFRs and 10 L-OPFRs in a tropical estuarine food web from Hainan Island, China. Notably, the Σ10L-OPFRs concentration (16.1-1.18 × 105 lipid weight (lw)) was significantly greater than that of Σ8E-OPFRs (nondetectable (nd) - 2.82 × 103 ng/g lw) among the investigated organisms, and they both exhibited similar trends: fish<mollusk<crustacean. Significant biomagnification was found only for triphenyl phosphate (TPHP, an L-OPFR) with a trophic magnification factor (TMF) of 1.55, whereas other E- and L-OPFRs showed limited trophic transfer potential. Storage lipid was the dominant adsorption phase for most E-OPFRs and L-OPFRs on the basis of the fugacity approach. The water content controls the main trophic partitioning for the L-OPFRs of triethyl phosphate (TEP) and tris(2-chloroethyl) phosphate (TCEP) in the food web. Storage lipid and structure protein are equally important for 2,2-bis(chloromethyl)-propane-1,3-diyltetrakis(2-chloroethyl) biphosphate (V6, an emerging OPFR). The investigation of metabolites and the biotransformation rate (K M) confirmed the role of biotransformation in offsetting trophic transfer for both legacy and emerging OPFRs. Furthermore, the hazard quotients (HQs) were found to be <1 for South China residents for both the E- and L-OPFRs, but the health risks of these two kinds of OPFRs should be given sustained attention.

Occurrence, Bioaccumulation, and Trophic Transfer of Short-Chain Chlorinated Paraffins (SCCPs) in a Marine Food Web from Laizhou Bay, Bohai Sea (Eastern China).

Short-chain chlorinated paraffins (SCCPs) are a persistent organic pollutant, and limited information is available on their bioaccumulation and trophic transfer, which would be affected by carbon chain length, chlorine content, and hydrophobicity. In this study, relevant data on SCCPs in water, sediments, and organisms collected from Laizhou Bay were analyzed to investigate the specific distribution of SCCPs and their bioaccumulation and trophic transfer. In water and sediments, the average SCCP concentrations (ΣSCCPs) were 362.23 ± 81.03 ng/L and 609.68 ± 90.28 ng/g d.w., respectively. In 28 species of organisms, the ΣSCCPs varied from 70.05 to 47,244.13 ng/g l.w. (average = 648 ± 7360) and the predominant homologs were C13 (average = 34.91%) and Cl5-7 (average = 93.13%), differing from those in water (average = C11 32.75% and average = Cl5-7 88%) and sediments (average = C13 31.60% and average = Cl6-8 87.16%). The logarithm bioaccumulation factors (BAFs) of ΣSCCPs were 1.18-2.74 and were positively correlated with the log Kow. A significant negative linear relationship was observed between biota-sediment accumulation factors (BSAFs) and log Kow. It is suggested that the hydrophobicity may affect the bioaccumulation of SCCPs. SCCPs demonstrated a trophic magnification factor (TMF) ranging from 2.19 to 3.00 (average = 2.51) and exhibited a significant linear correlation with carbon chain length (p < 0.05) and log Kow values (p < 0.05), suggesting that SCCPs have biomagnification potential in Laizhou Bay that is affected by hydrophobicity and carbon chain length.

Optical Automatic Contour Tracing (O-ACT) - A novel optical image-guided contour tracing method for electron beam shaping.

Electron therapy, vital for treating skin lesions and superficial tumors, demands precise electron cutouts to ensure accurate dose delivery. Traditional manual tracing methods introduce uncertainties and inefficiencies, necessitating innovative solutions for custom block creation. To introduce and validate the Optical Automatic Contour Tracing (O-ACT) method, enhancing electron cutout generation's accuracy and efficiency through optical imaging and software automation. Utilizing a 3D-printed holder, a centrally-mounted charge-coupled device (CCD) camera on the electron applicator secured two distinct perspective images of the skin's contour at varying heights. Through image binarization and skeletonization, we identified the clinical target contour's region-of-interests (ROIs) in each setup image. Employing distances from each ROI's center, assessed at 5-degree intervals from both images, we reconstructed the target contour on the skin. The magnification factor, set at a 95cm source-to-point distance, determined the final cutout shape. We crafted an in-house software in MATLAB for camera calibration and image processing and juxtaposed our results against the standard clinical cutout from the treatment planning system (TPS) using a correlation coefficient based on masked binary images' mutual information. Additionally, we performed dosimetric evaluations using abstract shapes to compare O-ACT with other methods. Our methodology yielded cutout shapes exhibiting remarkable alignment with the TPS clinical cutout. O-ACT demonstrated superior precision in generating cutout shapes that closely align with the contours in TPS, improving upon other methods in terms of adaptability to patient body shapes and contour accuracy. Dosimetric evaluations showed minimal differences between methods, with O-ACT providing slightly more consistent results. Dose profile analyses in penumbra regions indicated O-ACT's improved accuracy compared to conventional methods. Pushing the boundaries of traditional practices, our O-ACT offers a more accurate, efficient, and reproducible method for custom electron cutout creation from clinical setup images. This innovation promises not only to streamline clinical workflow but also to potentially uplift clinical outcomes in radiation oncology by providing more accurate patient-specific treatment accessary.

A Young Super Star Cluster Powering a Nebula of Retained Massive Star Ejecta

We suggest that “Godzilla” of the lensed Sunburst galaxy (z = 2.37) is a young super star cluster powering a nebula of gravitationally trapped stellar ejecta. Employing Hubble Space Telescope photometry and spectroscopy from the Very Large Telescope (VLT) MUSE and VLT/X-Shooter, we infer the physical and chemical properties of the cluster and nebula, finding that Godzilla is young, 4–6 Myr; massive, 2 × 106 M ⊙ (1000/μ); of stellar metallicity, Z ≃ 0.25 Z ⊙; and has a compact far-UV component of ≲1 pc (1000/μ), where μ is the flux magnification factor. The gas is significantly enriched with N and He, indicating stellar wind material, and has highly elevated O relative to the stellar metallicity, indicating entrainment of core-collapse supernova (CCSN) ejecta. The high density, n e ≃ 107−8 cm−3, implies a highly pressurized intracluster environment. We propose that the pressure results from CCSN-driven supersonic turbulence in warm, self-shielding gas, which has accumulated in the cluster center after runaway radiative cooling and is dense enough to resist removal by CCSNe. The nebula gas shows subsolar C/O, Ne/O, and Si/O, which may reflect the CCSN element yields for initial stellar masses >40 M ⊙. A comparison to element yield synthesis models for young star clusters shows that the gas abundances are consistent with complete retention and mixture of stellar winds and CCSN ejecta until the inferred cluster age. The inferred O and He enhancement may have implications for the formation of multiple stellar populations in globular clusters, as stars formed from this gas would contradict the observed abundances of second-population stars.

Dynamic analysis of orthotropic bridge deck under moving vehicular loads by using Hencky bar-net model

This study extends the Hencky Bar-Net model (HBM) to dynamic analysis of vehicle-orthotropic bridge deck interaction system. The HBM was used to investigate the dynamic behaviour of an orthotropic bridge deck under moving vehicular loads and random road irregularities. The results indicate that the lower bending rigidity in width direction change the deformations of orthotropic deck from a global mode into a localized one, and dynamic magnification factors do not necessarily increase with higher vehicle speeds. However, dynamic magnification factors demonstrate an obvious increase in relation to higher vehicle speeds when the bending rigidity ratio is high. In addition, the HBM can easily handle damage of the bridge deck because of its discrete characteristic. Hence, the common longitudinal cracks that keep open are modelled by reducing the spring stiffness in the HBM. The results demonstrate longitudinal cracks show a complex influence on dynamic magnification factors of the bridge deck depending on the crack depth and location.

Association analysis of Talbot positive self-image and negative self-image for spherical wave illuminating on planar grating

Based on planar grating Fresnel diffraction theory, the correlation between Talbot positive self-image and negative self-image for spherical wave illuminating on planar grating is analyzed by theoretical and experimental methods. The results indicate that Talbot positive and negative self-images of orders 0 and ±1 show a checkerboard shape with periodic structure, with opposite phases when the period magnification factor M is the same. However, the detail of Talbot positive self-image is more detailed than the negative self-image, due to phase reversal and changes in Talbot distance, which imply a relationship of mutual constraints between the two images. Additionally, the peak light intensity of positive and negative self-image increases with the increase of M. Talbot positive and negative self-image are observed at corresponding Talbot distance by theoretical and experimental results, and Talbot distance of the two Talbot images is obviously divided into rapidly decreasing and slowly changing as z 0 increases.

From Trophic Magnification Factors to Multimedia Activity Ratios: Chemometers as Versatile Tools to Study the Fate of Hydrophobic Organic Compounds in Aquatic Ecosystems.

We applied passive equilibrium sampling using silicone-based chemometers to nine biota species, sediment, and water in a multimedia aquatic ecosystem. They allowed for direct comparison of the concentration of regulated and emerging hydrophobic organic compounds in the silicone across species as well as the comparison of biota with sediments and water. We derived chemometer-based trophic magnification factors (TMFs) of diverse compounds that agreed with the traditionally derived TMFs. Our exploratory work in water demonstrated that equilibrium with newly designed chemometers can be achieved in few days for compounds with a log KOW up to 6. We calculated activity ratios, dividing the concentrations in the silicone equilibrated with biota by those equilibrated with the abiotic exposure media (sediments and water), assessing the thermodynamics of bioaccumulation and the equilibrium state between the ecosystem compartments. They confirmed that the biota were below equilibrium partitioning relative to sediments and water, as other studies have described. Silicone-based chemometers open up new opportunities and applicability in multimedia aquatic ecosystems for studies that rely on equilibrium partitioning of the in-situ mixtures of chemicals, such as multimedia assessments or application of effect-based methods.

Fusing global context with multiscale context for enhanced breast cancer classification

Breast cancer is the second most common type of cancer among women. Prompt detection of breast cancer can impede its advancement to more advanced phases, thereby elevating the probability of favorable treatment consequences. Histopathological images are commonly used for breast cancer classification due to their detailed cellular information. Existing diagnostic approaches rely on Convolutional Neural Networks (CNNs) which are limited to local context resulting in a lower classification accuracy. Therefore, we present a fusion model composed of a Vision Transformer (ViT) and custom Atrous Spatial Pyramid Pooling (ASPP) network with an attention mechanism for effectively classifying breast cancer from histopathological images. ViT enables the model to attain global features, while the ASPP network accommodates multiscale features. Fusing the features derived from the models resulted in a robust breast cancer classifier. With the help of five-stage image preprocessing technique, the proposed model achieved 100% accuracy in classifying breast cancer on the BreakHis dataset at 100X and 400X magnification factors. On 40X and 200X magnifications, the model achieved 99.25% and 98.26% classification accuracy respectively. With a commendable classification efficacy on histopathological images, the model can be considered a dependable option for proficient breast cancer classification.

Compensation of isotope ratio mismatch in double isotope dilution inductively coupled plasma mass spectrometry (ID-ICP/MS)

Abstract Exact-matching double isotope dilution inductively coupled plasma mass spectrometry (ID-ICP/MS) is widely used to characterize reference materials (RMs) in elemental analysis. In this technique, achieving exactly matching isotope ratios for the sample and calibration blends is regarded as an important prerequisite for obtaining accurate measurement results. However, meeting this condition requires multiple time-consuming iterative measurements. In the current study, an alternative approach that can avoid lengthy iterative procedures while maintaining the accuracy of the ID-ICP/MS results was successfully investigated. We examined the effects of an extensively wide range of inexact-matching isotope ratios (approximately 75%–130%) in double ID-ICP/MS for elements with a wide mass range. Our experimental study, using gravimetrically prepared samples of Ca, Cd, Cu, Fe, Hg, Mg, Ni, Pb, and Zn, demonstrated that, despite deliberately introducing mismatching of isotope ratios, the accuracy of the ID-ICP/MS results remained consistent with relative measurement bias of typically less than 0.5%. The absence of a systematic bias due to deviations in the sample blend isotope ratios from the target ratios of the calibration blends revealed that the variability due to an isotope ratio mismatch was sufficiently compensated for. Furthermore, the expanded measurement uncertainties were sufficiently small with negligible variations observed across the different matching ratios. Typically, they were less than 1%, except for Fe, Hg, Pb, and Zn which were less than 2%. This assertion is also supported by theoretically calculated error magnification factors. Consequently, it is feasible to directly utilize the marginally estimated mass fraction of the analyte of interest without extensive iterative measurements. The findings of this study provide robust data for ID-ICP/MS, allowing to circumvent lengthy iterative procedures while maintaining the accuracy and precision of the measurement results, particularly in the characterization of RMs for elemental analysis.

HADT: Image super-resolution restoration using Hybrid Attention-Dense Connected Transformer Networks

Image super-resolution (SR) plays a vital role in vision tasks, in which Transformer-based methods outperform conventional convolutional neural networks. Existing work usually uses residual linking to improve the performance, but this type of linking provides limited information transfer within the block. Also, existing work usually restricts the self-attention computation to a single window to improve feature extraction. This means transformer-based networks can only use feature information within a limited spatial range. To handle the challenge, this paper proposes a novel Hybrid Attention-Dense Connected Transformer Network (HADT) to utilize the potential feature information better. HADT is constructed by stacking an attentional transformer block (ATB), which contains an Effective Dense Transformer Block (EDTB) and a Hybrid Attention Block (HAB). EDTB combines dense connectivity and swin-transformer to enhance feature transfer and improve model representation, and meanwhile, HAB is used for cross-window information interaction and joint modeling of features for better visualization. Based on the experiments, our method is effective on SR tasks with magnification factors of 2, 3, and 4. For example, using the Urban100 dataset in an experiment with an amplification factor of 4 our method has a PSNR value that is 0.15 dB higher than the previous method and reconstructs a more detailed texture.

The trophodynamics of polycyclic aromatic hydrocarbons in marine food webs: The importance of trophic level span from insights into Liaodong Bay (China)

The occurrence and trophic transfer of polycyclic aromatic hydrocarbons (PAHs) in aquatic ecosystems is vital to assess ecological risks. PAHs concentrations were analyzed in seawater, sediment, plankton, and marine species (15 fish species, 8 invertebrate species, 3 marine mammals), collected from Liaodong Bay (China). Bioaccumulation and biomagnification were calculated to demonstrate the biotransfer pattern of PAHs from the environmental matrix to high-level predators through the food web. Total PAHs concentrations ranged from 81.2 to 197.6 ng/L in seawater, 51.4–304.8 ng/g (dw) in sediment, and 65.3 to 28,885 ng/g (lw) in all biota samples. Three- and four-ring PAHs constituted major components (>81% in each case) of PAH congener profiles. Lower biota-sediment accumulation factors (BSAFs) and bioaccumulation factors (BAFs) values indicated limited bioaccumulation of PAHs within marine organisms. Also, 77% of biomagnification factors (BMFTL) values of PAHs in spotted seal and finless porpoise were >1, whereas opposite transfer patterns of PAHs were observed in food webs with trophic values of 1.5–3.5 and 3.0–4.0; that is, trophic dilution (trophic magnification factor (TMF) < 1) and trophic magnification (TMF >1), respectively. This study provides novel insights into the importance of TL span for trophodynamics of PAHs within food webs.

Analytical solution of a microrobot-blood vessel interaction model

This study develops a dynamics model of a microrobot vibrating in a blood vessel aiming to detect potential cancer metastasis. We derive an analytical solution for microrobot’s motion, considering interactions with the vessel walls modelled by a linear spring-dashpot and a constant damping value for blood viscosity. The model facilitates instantaneous state transitions of the microrobot, such as contact with the vessel wall and free motion within the fluid. Amplitudes and phase angles from the transient solutions of dynamics model of the microrobot are solved at arbitrary moments, providing insights into its transient dynamics. The analytical solution of the proposed system is validated by experimental data, serving as a benchmark to examine the influence of pertinent parameters on microrobot’s dynamic response. It is found that the contact force transmitted to the vessel wall, assessed by system’s transmissibility function dependent on damping and frequency ratios, decreases with increasing damping ratio and intensifies when the frequency ratio is below 2. At the frequency ratio is equal to 1, resonance phenomenon is dominated by the magnification factor linked to the damping ratio, increasing the amplitude of resonance as damping decreases. Finally, different sets of system parameters, including excitation frequency and magnitude, fluid damping, vessel wall’s stiffness and damping, reveal multi-periodic motions and fake collision of the microrobot with the vessel wall. Simulation results imply that these phenomena are minimally affected by vessel wall’s stiffness but are significantly influenced by other parameters, such as fluid damping coefficient and damping coefficient of the blood vessel wall. This research provides a robust theoretical foundation for developing control strategies for microrobots aimed at detecting cancer metastasis.

High-Sensitivity Displacement Sensor Using Few-Mode Optical Fibers and the Optical Vernier Effect

This paper presents a displacement sensor designed to achieve the Optical Vernier Effect (OVE) through a simple yet robust configuration, enhancing sensitivity and precision in small displacement measurements. The sensor structure comprises a few-mode fiber (FMF) placed between two single-mode fibers (SMF) in an SMF-FMF-SMF (SFS) configuration. A series of distinct configurations of concatenated Mach–Zehnder fiber interferometers (MZFI) were examined, with the lengths of the reference FMF (FMFRef) and sensing FMF (FMFSen) adjusted to track the spectral envelope shifts. The results demonstrate that the direction of the spectral shift is governed by the ratio between the FMFRef and FMFSen lengths. The sensor achieved a sensitivity of up to 39.07 nm/mm and a magnification factor (M factor) of up to 50.09, demonstrating exceptional precision and adaptability across a range of applications. The proposed configuration also enhances the overall sensor performance, highlighting its potential for broader use in fields requiring precise displacement monitoring.

A Meta-Analysis of Mercury Biomagnification in Freshwater Predatory Invertebrates: Community Diversity and Dietary Exposure Drive Variability.

Accurate estimates of methylmercury (MeHg) exposure are valuable to actionably assess risk and protect wildlife and human health. MeHg trophic transfer is a critical driver of risk: MeHg is generally biomagnified by a factor of 8.3 ± 7.5 from one trophic level to the next, averaged across freshwater communities (mean ± standard deviation). This variability can produce disparate risks even where basal MeHg concentrations are similar. Taxonomy may be one driver of this variability: physiologically diverse groups, like vertebrates and invertebrates, may assimilate MeHg differently. To determine whether taxonomy affects trophic transfer efficiency, we conducted a meta-analysis characterizing predatory invertebrate MeHg biomagnification. Our analyses estimated that freshwater predatory invertebrates biomagnify MeHg by factors of 2.1 ± 0.2 to 4.3 ± 0.3, with a 98.9 ± 0.4% posterior probability that factors are below 5 (mean ± standard error). When vertebrates or primary producers were included, a site's trophic magnification factor was 18.6 ± 6.2 to 54.1 ± 7.7% higher than estimates for invertebrates alone. Biomagnification was inversely correlated to prey MeHg concentration and varied among systematic and functional groups. These data suggest that predatory invertebrates biomagnify MeHg less efficiently than vertebrates and that a community's diversity and structure determine its biomagnification efficiency. Incorporating organismal variation in trophic transfer estimates may improve the assessment, communication, and management of MeHg risk.