Changes In Frequency Research Articles

Determining the toxicological effects of indoor air pollution on both a healthy and an inflammatory-comprised model of the alveolar epithelial barrier in vitro.

Exposure to indoor air pollutants (IAP) has increased recently, with people spending more time indoors (i.e. homes, offices, schools and transportation). Increased exposures of IAP on a healthy population are poorly understood, and those with allergic respiratory conditions even less so. The objective of this study, therefore, was to implement a well-characterised in vitro model of the human alveolar epithelial barrier (A549 + PMA differentiated THP-1 incubated with and without IL-13, IL-5 and IL-4) to determine the effects of a standardised indoor particulate (NIST 2583) on both a healthy lung model and one modelling a type-II (stimulated with IL-13, IL-5 and IL-4) inflammatory response (such as asthma).Using concentrations from the literature, and an environmentally appropriate exposure we investigated 232, 464 and 608ng/cm2 of NIST 2583 respectively. Membrane integrity (blue dextran), viability (trypan blue), genotoxicity (micronucleus (Mn) assay) and (pro-)/(anti-)inflammatory effects (IL-6, IL-8, IL-33, IL-10) were then assessed 24 h post exposure to both models. Models were exposed using a physiologically relevant aerosolisation method (VitroCell Cloud 12 exposure system).No changes in Mn frequency or membrane integrity in either model were noted when exposed to any of the tested concentrations of NIST 2583. A significant decrease (p < 0.05) in cell viability at the highest concentration was observed in the healthy model. Whilst cell viability in the "inflamed" model was decreased at the lower concentrations (significantly (p < 0.05) after 464ng/cm2). A significant reduction (p < 0.05) in IL-10 and a significant increase in IL-33 was seen after 24 h exposure to NIST 2583 (464, 608ng/cm2) in the "inflamed" model.Collectively, the results indicate the potential for IAP to cause the onset of a type II response as well as exacerbating pre-existing allergic conditions. Furthermore, the data imposes the importance of considering unhealthy individuals when investigating the potential health effects of IAP. It also highlights that even in a healthy population these particles have the potential to induce this type II response and initiate an immune response following exposure to IAP.

The impact of the COVID-19 pandemic on people who use drugs in three Canadian cities: a cross-sectional analysis

BackgroundThe COVID-19 pandemic had a disproportionate impact on the health and wellbeing of people who use drugs (PWUD) in Canada. However less is known about jurisdictional commonalities and differences in COVID-19 exposure and impacts of pandemic-related restrictions on competing health and social risks among PWUD living in large urban centres.MethodsBetween May 2020 and March 2021, leveraging infrastructure from ongoing cohorts of PWUD, we surveyed 1,025 participants from Vancouver (n = 640), Toronto (n = 158), and Montreal (n = 227), Canada to describe the impacts of pandemic-related restrictions on basic, health, and harm reduction needs.ResultsAmong participants, awareness of COVID-19 protective measures was high; however, between 10 and 24% of participants in each city-specific sample reported being unable to self-isolate. Overall, 3–19% of participants reported experiencing homelessness after the onset of the pandemic, while 20–41% reported that they went hungry more often than usual. Furthermore, 8–33% of participants reported experiencing an overdose during the pandemic, though most indicated no change in overdose frequency compared the pre-pandemic period. Most participants receiving opioid agonist therapy in the past six months reported treatment continuity during the pandemic (87–93%), however, 32% and 22% of participants in Toronto and Montreal reported missing doses due to service disruptions. There were some reports of difficulty accessing supervised consumption sites in all three sites, and drug checking services in Vancouver.ConclusionFindings suggest PWUD in Canada experienced difficulties meeting essential needs and accessing some harm reduction services during the COVID-19 pandemic. These findings can inform preparedness planning for future public health emergencies.

The impact of the COVID-19 pandemic on calls to an alcohol and drug helpline in Victoria, Australia, for alcohol, methamphetamine and cannabis use concerns.

Helplines are often the first contact with the alcohol and other drug (AOD) treatment system. We examined call data from an AOD helpline in Victoria, Australia, to explore the association between COVID-19 lockdown measures and frequency of calls. This was a retrospective analysis of AOD helpline data collected between January 2018 and September 2020, for alcohol, methamphetamine and cannabis use concerns. Linear and logistic regression analyses examined differences in pre-COVID-19 (January 2018 to March 2020) and during COVID-19 (March 2020 to September 2020) caller characteristics, and interrupted time-series analyses examined changes in frequency of calls relative to lockdown measures. There were 14,340 calls for alcohol (n = 10,196, 71.10%), methamphetamine (n = 2522, 17.59%) and cannabis (n = 1622, 11.31%). Relative to pre-COVID-19, during COVID-19 there was an increase in the rate of change over time in number of alcohol calls (b = 0.39), increase in first-time alcohol callers (OR = 1.29), and reduction in first-time methamphetamine callers (OR = 0.80). During COVID-19, alcohol callers had lower Socio-Economic Indicators for Areas scores (b = -3.06) and cannabis callers were younger (b = -2.07). During COVID-19, there were reductions in alcohol calls involving counselling/support (OR = 0.87) and information provision (OR = 0.87), cannabis calls involving information provision (OR = 0.71) and methamphetamine calls involving referral (OR = 0.80). In the first 6 months of the pandemic, frequency of alcohol-related calls increased over time, and first-time alcohol-related callers increased. The number of calls for cannabis and methamphetamine remained stable. Results suggest the helpline was not used to its full capacity, suggesting a role for further promotion during times of crises.

Vagus nerve stimulation in bursts can efficiently modulate gastric contractions and contraction frequency at varying gastric pressures.

There has been recent clinical interest in the use of vagus nerve stimulation (VNS) for treating gastrointestinal disorders as an alternative to drugs or gastric electrical stimulation. However, effectiveness of burst stimulation has not been demonstrated. We investigated the ability of bursting and continuous VNS to influence gastric and pyloric activity under a range of stimulation parameters and gastric pressures. The goals of this study were to determine which parameters could optimally excite or inhibit gastric activity. Data were collected from 21 Sprague-Dawley rats. Under urethane anesthesia, a rubber balloon was implanted into the stomach, connected to a pressure transducer and a saline infusion pump. A pressure catheter was inserted at the pyloric sphincter and a bipolar nerve cuff was implanted onto the left cervical vagus nerve. The balloon was filled to 15 cmH2O. Stimulation trials were conducted in a consistent order; the protocol was then repeated at 25 and 35 cmH2O. The nerve was then transected and stimulation repeated to investigate directionality of effects. Bursting stimulation at the bradycardia threshold caused significant increases in gastric contraction amplitude with entrainment to the bursting frequency. Some continuous stimulation trials could also cause increased contractions but without frequency changes. Few significant changes were observed at the pylorus, except for frequency entrainment. These effects could not be uniquely attributed to afferent or efferent activity. Our findings further elucidate the effects of different VNS parameters on the stomach and pylorus and provide a basis for future studies of bursting stimulation for gastric neuromodulation.

Numerical Simulation Analysis of the Correlation between Hydrodynamic Noise of Hydraulic Turbines and Defects in Runner Blades

To investigate the hydrodynamic noise characterization of hydraulic turbines with runner blade defects, this article establishes the intact machine model and three kinds of models with runner blade defects. Using the Computational Fluid Dynamic (CFD) and Computational Acoustic (CA) hybrid simulation computational methods, the hydrodynamic noise field of the hydraulic turbine is numerically simulated, and the results of the acoustic near field and acoustic far field are shown. 1. The double-row leaf grille and the runner are the primary sound source areas of the hydraulic turbine, and the intensity of sound radiation from these areas is positively correlated with the degree of runner blade defects. 2. As the runner blade defects develop, the sound power level (SWL) increases more significantly in the guide vanes near the nose of the spiral case in the double-row leaf grille. The most pronounced increase in the SWL is observed at the defective craters on the runner blades. 3. The frequency of the defective noise signal is primarily concentrated in the low-frequency band. The dominant frequency amplitude associated with runner blade defects increases and rises after the occurrence of defects. Secondary frequency changes are also observed, and the location of these changes varies at different receiving points.

Moisture-induced power generator fabricated on a lateral field-excited quartz resonator

We fabricated a moisture-induced power generator on a lateral field-excited quartz resonator to simultaneously measure changes in mass and voltage generation during water vapor adsorption. Circularly interdigitated gold electrodes were vacuum deposited on the top surface and used to measure changes in mass, and two symmetric semicircular gold electrodes were vacuum deposited on the bottom surface and used to measure changes in voltage generation. After coating a thin film of a mixture comprising sodium alginate, carbon black, and polyvinyl alcohol (SCP) on the top surface, an electric field was applied to create a concentration gradient of sodium ions between the interdigitated electrodes. The changes in the resonant frequency and voltage generation of the SCP-coated quartz resonator were measured simultaneously under various relative humidity conditions. The results revealed, for the first time, three distinct voltage-generation regions during moisture adsorption: (i) a region of negligible voltage generation, (ii) that of an increase in voltage generation, and (iii) that of a decrease in voltage generation.

Deformable motion compensation in interventional cone-beam CT with a context-aware learned autofocus metric.

Interventional Cone-Beam CT (CBCT) offers 3D visualization of soft-tissue and vascular anatomy, enabling 3D guidance of abdominal interventions. However, its long acquisition time makes CBCT susceptible to patient motion. Image-based autofocus offers a suitable platform for compensation of deformable motion in CBCT, but it relies on handcrafted motion metrics based on first-order image properties and that lack awareness of the underlying anatomy. This work proposes a data-driven approach to motion quantification via a learned, context-aware, deformable metric, , that quantifies the amount of motion degradation as well as the realism of the structural anatomical content in the image. The proposed was modeled as a deep convolutional neural network (CNN) trained to recreate a reference-based structural similarity metric-visual information fidelity (VIF). The deep CNN acted on motion-corrupted images, providing an estimation of the spatial VIF map that would be obtained against a motion-free reference, capturing motion distortion, and anatomic plausibility. The deep CNN featured a multi-branch architecture with a high-resolution branch for estimation of voxel-wise VIF on a small volume of interest. A second contextual, low-resolution branch provided features associated to anatomical context for disentanglement of motion effects and anatomical appearance. The deep CNN was trained on paired motion-free and motion-corrupted data obtained with a high-fidelity forward projection model for a protocol involving 120kV and 9.90mGy. The performance of was evaluated via metrics of correlation with ground truth and with the underlying deformable motion field in simulated data with deformable motion fields with amplitude ranging from 5 to 20mm and frequency from 2.4 up to 4 cycles/scan. Robustness to variation in tissue contrast and noise levels was assessed in simulation studies with varying beam energy (90-120kV) and dose (1.19-39.59mGy). Further validation was obtained on experimental studies with a deformable phantom. Final validation was obtained via integration of on an autofocus compensation framework, applied to motion compensation on experimental datasets and evaluated via metric of spatial resolution on soft-tissue boundaries and sharpness of contrast-enhanced vascularity. The magnitude and spatial map of showed consistent and high correlation levels with the ground truth in both simulation and real data, yielding average normalized cross correlation (NCC) values of 0.95 and 0.88, respectively. Similarly, achieved good correlation values with the underlying motion field, with average NCC of 0.90. In experimental phantom studies, properly reflects the change in motion amplitudes and frequencies: voxel-wise averaging of the local across the full reconstructed volume yielded an average value of 0.69 for the case with mild motion (2mm, 12 cycles/scan) and 0.29 for the case with severe motion (12mm, 6 cycles/scan). Autofocus motion compensation using resulted in noticeable mitigation of motion artifacts and improved spatial resolution of soft tissue and high-contrast structures, resulting in reduction of edge spread function width of 8.78% and 9.20%, respectively. Motion compensation also increased the conspicuity of contrast-enhanced vascularity, reflected in an increase of 9.64% in vessel sharpness. The proposed , featuring a novel context-aware architecture, demonstrated its capacity as a reference-free surrogate of structural similarity to quantify motion-induced degradation of image quality and anatomical plausibility of image content. The validation studies showed robust performance across motion patterns, x-ray techniques, and anatomical instances. The proposed anatomy- and context-aware metric poses a powerful alternative to conventional motion estimation metrics, and a step forward for application of deep autofocus motion compensation for guidance in clinical interventional procedures.

Salud mental durante el confinamiento por COVID-19. El caso del personal de una universidad del caribe colombiano

Objective: To describe the levels of stress, anxiety and depression during a period of confinement by COVID-19 in students, teachers and administrative staff of a Colombian university. Materials and methods: Quantitative, observational, descriptive and cross-sectional study. There were 1,318 individuals without diagnosed mental illnesses who agreed to participate in the study by signing an informed consent. A sociodemographic record was created to measure variables of interest and the Abbreviated Depression, Anxiety and Stress Scale (DASS-21). Descriptive statistics were reported and Odds ratio (OR) with 95% confidence intervals were calculated. Results: In 40.3% (N = 531) of the cases there was depression, in 42.6% (N = 562) anxiety and in 44.6% (N = 588) stress; Being a woman, economic income being affected, increased academic / work load and changes in sleep frequency, quality and / or habits, were found to be significant risk factors for depression, anxiety and stress. Conclusions: There is a high percentage of the presence of affective states of depression, anxiety and stress at the different intensity levels calculated by the DASS-21 in the study group during the pandemic period studied.

Allele frequency dynamics under sex-biased demography and sex-specific inheritance in a pedigreed jay population

Abstract Sex-biased demography, including sex-biased survival or migration, can alter allele frequency changes across the genome. In particular, we can expect different patterns of genetic variation on autosomes and sex chromosomes due to sex-specific differences in life histories, as well as differences in effective population size, transmission modes, and the strength and mode of selection. Here, we demonstrate the role that sex differences in life history played in shaping short-term evolutionary dynamics across the genome. We used a 25-year pedigree and genomic dataset from a long-studied population of Florida Scrub-Jays (Aphelocoma coerulescens) to directly characterize the relative roles of sex-biased demography and inheritance in shaping genome-wide allele frequency trajectories. We used gene dropping simulations to estimate individual genetic contributions to future generations and to model drift and immigration on the known pedigree. We quantified differential expected genetic contributions of males and females over time, showing the impact of sex-biased dispersal in a monogamous system. Due to female-biased dispersal, more autosomal variation is introduced by female immigrants. However, due to male-biased transmission, more Z variation is introduced by male immigrants. Finally, we partitioned the proportion of variance in allele frequency change through time due to male and female contributions. Overall, most allele frequency change is due to variance in survival and births. Males and females make similar contributions to autosomal allele frequency change, but males make higher contributions to allele frequency change on the Z chromosome. Our work shows the importance of understanding sex-specific demographic processes in characterizing genome-wide allele frequency change in wild populations.

Deep genotyping reveals specific adaptation footprints of conventional and organic farming in barley populations—an evolutionary plant breeding approach

Sustainable food production for a growing world population will pose a central challenge in the coming decades. Organic farming is among the feasible approaches to achieving this goal if the yield gap to conventional farming can be decreased. However, uncertainties exist to which extend—and for which phenotypes in particular—organic and conventional agro-ecosystems require differentiated breeding strategies. To answer this question, a heterogeneous spring barley population was established between a wild barley and an elite cultivar to examine this question. This initial population was divided into two sets and sown one in organic and the other in conventional managed agro-ecosystems, without any artificial selection for two decades. A fraction of seeds harvested each year was sown the following year. Various generations, up to the 23th were whole-genome pool-sequenced to identify adaptation patterns towards ecosystem and climate conditions in the allele frequency shifts. Additionally, a meta-data analysis was conducted to link genomic regions’ increased fitness to agronomically related traits. This long-term experiment highlights for the first time that allele frequency pattern difference between the conventional and organic populations grew with subsequent generations. Further, the organic-adapted population showed a higher genetic heterogeneity. The data indicate that adaptations towards new environments happen in few generations. Drastic interannual changes in climate are manifested in significant allele frequency changes. Particular wild form alleles were positively selected in both environments. Clustering these revealed an increased fitness associated with biotic stress resistance, yield physiology, and yield components in both systems. Additionally, the introduced wild alleles showed increased fitness related to root morphology, developmental processes, and abiotic stress responses in the organic agro-ecosystem. Concluding the genetic analysis, we demonstrate that breeding of organically adapted varieties should be conducted in an organically managed agro-ecosystem, focusing on root-related traits, to close the yield gap towards conventional farming.

Knowledge-shareable adaptive deep dynamic programming for hierarchical generation control of distributed high-percentage renewable energy systems

The increased proportion of distributed renewable energy sources connected to systems leads to frequency regulation difficulty, such as uncoordinated algorithms, inconsistent optimization and control objectives, and long training time. This work proposes a knowledge-shareable adaptive deep dynamic programming (KSADDP) to improve the active control accuracy and generation economy of the proposed hierarchical generation control framework, which contains two-layer control structures. In the first layer, droop control is employed to optimize the outputs of controllable generators, follow the frequency changes, reduce frequency deviation, and improve the operation economy of battery energy storage systems. In the second layer, a KSADDP is proposed to mitigate local optimum and accelerate the hybrid cooperative structure optimization by sharing the parameters of neural networks. These two layers synergistically optimize control performance and reduce generation costs. The simulation results of a three-high-percentage renewable energy system show that: with two layers of cooperation and sharing training information, the KSADDP outperforms the comparison algorithms in seven evaluation indices and reduces the generation cost by 4.85%–7.41 % compared to the comparison algorithms. The proposed KSADDP cooperates the time scales between multiple layers, cooperates the objectives between multiple layers, increases the parameter-sharing process, and reduces training time.

Design, fabrication, and evaluation of a novel highly sensitive tuning fork pressure sensor for precise liquid level measurement

This article investigates the under-explored potential of utilizing a thin stainless-steel diaphragm coupled with a quartz tuning fork sensor for liquid depth measurements. The focus is on monitoring molten salt fluid levels in nuclear reactors and concentrated solar power systems. Addressing a literature gap, the research explores cantilever-type configurations of a double-ended quartz tuning fork resonator, with a no-load resonance frequency of 17.37 kHz, on thin stainless-steel diaphragms for fluid depth measurement at room temperature. As the fluid depth increases, hydro-static pressure acting on a 20 μm diaphragm causes deflection, bending a tuning fork. The resulting change in resonance frequency correlates with fluid depth. Experimental setups assess the tuning fork’s sensitivity to strain and bending, revealing strain sensitivity of 7.83 Hz/μ strain (450.78 ppm/μ strain) and bending sensitivity of 0.09 Hz/μm (5.18 ppm/μm). The pressure sensor assembly, tested in a water tank, exhibits a sensitivity of −0.28 Hz/mm (−16.12 ppm/mm) in a single cantilever-type configuration. Despite a limited linear range, it effectively measures water depth changes as small as 0.7 mm. Exploring a double cantilever-type configuration yields a sensitivity of 0.07 Hz/mm (4.03 ppm/mm) with a broader linear range. The article discusses the reasons for opposite sensitivity and highlights the advantages of each configuration. Beyond molten salt level monitoring, the technology’s applications may extend to fluid depth and pressure measurements in industrial and domestic settings.

A Physics-Based Model-Data-Driven Method for Spindle Health Diagnosis, Part II: Dynamic Simulation and Validation

Abstract Mathematical modeling of bearing faults, worn tool holder taper contact interface, and unbalance are presented and integrated into a digital dynamic model of spindles in Part I of this paper. These faults lead to changes in preload and dynamic stiffness over time, consequently resulting in observable vibrations. This paper predicts the vibrations of a spindle at a particular measurement location by simulating the presence of a specific fault or multiple faults during spindle rotation. The vibration spectra generated by the digital spindle model at the spindle speed and its harmonics, the changes in the natural frequencies, and dynamic stiffnesses are correlated to faults with experimental validations. The simulated vibration spectrums are later used in training an artificial neural network for fault condition monitoring presented in Part III of the paper.

The effect of hyperoxia on muscle sympathetic nerve activity: a systematic review and meta-analysis.

We conducted a meta-analysis to determine the effect of hyperoxia on muscle sympathetic nerve activity in healthy individuals and those with cardio-metabolic diseases. A comprehensive search of electronic databases was performed until August 2022. All study designs (except reviews) were included: population (humans; apparently healthy or with at least one chronic disease); exposures (muscle sympathetic nerve activity during hyperoxia or hyperbaria); comparators (hyperoxia or hyperbaria vs. normoxia); and outcomes (muscle sympathetic nerve activity, heart rate, blood pressure, minute ventilation). Forty-nine studies were ultimately included in the meta-analysis. In healthy individuals, hyperoxia had no effect on sympathetic burst frequency (mean difference [MD] -1.07 bursts/min; 95% confidence interval [CI] -2.17,0.04bursts/min; P = 0.06), burst incidence (MD 0.27 bursts/100 heartbeats [hb]; 95% CI -2.10,2.64 bursts/100 hb; P = 0.82), burst amplitude (P = 0.85), or total activity (P = 0.31). In those with chronic diseases, hyperoxia decreased burst frequency (MD -5.57 bursts/min; 95% CI -7.48, -3.67 bursts/min; P < 0.001) and burst incidence (MD -4.44 bursts/100 hb; 95% CI -7.94, -0.94 bursts/100 hb; P = 0.01), but had no effect on burst amplitude (P = 0.36) or total activity (P = 0.90). Our meta-regression analyses identified an inverse relationship between normoxic burst frequency and change in burst frequency with hyperoxia. In both groups, hyperoxia decreased heart rate but had no effect on any measure of blood pressure. Hyperoxia does not change sympathetic activity in healthy humans. Conversely, in those with chronic diseases, hyperoxia decreases sympathetic activity. Regardless of disease status, resting sympathetic burst frequency predicts the degree of change in burst frequency, with larger decreases for those with higher resting activity.

Selection leads to remarkable variability in the outcomes of hybridisation across replicate hybrid zones.

Hybrid zones have been viewed as an opportunity to see speciation in action. When hybrid zones are replicated, it is assumed that if the same genetic incompatibilities are maintaining reproductive isolation across all instances of secondary contact, those incompatibilities should be identifiable by consistent patterns in the genome. In contrast, changes in allele frequencies due to genetic drift should be idiosyncratic for each hybrid zone. To test this assumption, we simulated 20 replicates of each of 12 hybrid zone scenarios with varied genetic incompatibilities, rates of migration, selection and different starting population size ratios of parental species. We found remarkable variability in the outcomes of hybridisation in replicate hybrid zones, particularly with Bateson-Dobzhansky-Muller incompatibilities and strong selection. We found substantial differences among replicates in the overall genomic composition of individuals, including admixture proportions, inter-specific ancestry complement and number of ancestry junctions. Additionally, we found substantial variation in genomic clines among replicates at focal loci, regardless of locus-specific selection. We conclude that processes other than selection are responsible for some consistent outcomes of hybridisation, whereas selection on incompatibilities can lead to genomically widespread and highly variable outcomes. We highlight the challenge of mapping between pattern and process in hybrid zones and call attention to how selection against incompatibilities will commonly lead to variable outcomes. We hope that this study informs future research on replicate hybrid zones and encourages further development of statistical techniques, theoretical models and exploration of additional axes of variation to understand reproductive isolation.

Impact of Drought in Northeastern Algeria: Comparative Study of the SPI and SPEI Índices

Purpose: The study aimed to evaluate drought trends in Annaba, Algeria, considering global warming and extreme weather, using quantitative indices for improved drought comprehension and prediction. Theoretical Framework:The study assesses changes in drought frequency and severity in the Annaba region of Algeria due to global warming and extreme weather conditions. It employs quantitative indices to enhance drought understanding and prediction. Methodology: The study analyzes temperature and precipitation data (1981-2021) from an Annaba weather station to assess drought characteristics.Standardized indices (SPI, SPEI) and extreme value analysis (Generalized Pareto Distribution) are used to quantify drought intensity, duration, and temperature impacts. Findings: Our analyses reveal a critical divergence in drought assessment tools. While stable monthly temperatures suggest a constant influence on evapotranspiration, the SPEI index (including temperature) indicates increasing drought compared to the precipitation-only SPI. This highlights the importance of considering temperature alongside precipitation for accurate drought assessment. Research Practical and Social Implication: This study emphasizes the significance of considering the interplay among temperature, precipitation, and evapotranspiration for better understanding and predicting drought changes in the Annaba region, Algeria. These insights are crucial for sustainable water resource management and climate change adaptation in the region. Originality/Value:This study distinguishes itself by its comprehensive analysis of long-term climate data to examine drought trends in a specific region (Annaba, Algeria) severely impacted by climate change. By comparing the effectiveness of two drought indices (SPEI and SPI), it offers valuable insights into how to improve drought assessments by considering the role of temperature in evapotranspiration. This research enriches the existing literature on drought management and climate change adaptation, providing a valuable case study for similar arid and semi-arid regions worldwide.

Intrinsic negative Poisson’s ratio of the monolayer semiconductor β- TeO2

Monolayer semiconductors with unique mechanical responses are promising candidates for novel electromechanical applications. Here, through first-principles calculations, we discover that the monolayer β- TeO2 , a high-mobility p-type and environmentally stable 2D semiconductor, exhibits an unusual out-of-plane negative Poisson’s ratio (NPR) when a uniaxial strain is applied along the zigzag direction. The NPR originates from the unique six-sublayer puckered structure and hinge-like Te–O bonds in the 2D β- TeO2 . We further propose that the sign of the Raman frequency change under uniaxial tensile strain could assist in determining the lattice orientation of monolayer β- TeO2 , which facilitates the experimental study of the NPR. Our results is expected to motivate further experimental and theoretical studies of the rich physical and mechanical properties of monolayer β-TeO2.

Negative Dielectric Constant in Novel Structure of PA-GO Composite /MnO2/Fe3O4/n-Si

Abstract We present a novel structure of PA-GO composite /MnO2/Fe3O4/n-Si arranged by simple technique and examined by scanning electron microscope, X-ray diffraction, and Raman spectroscopy. The negative dielectric constant appeared for all voltages at frequencies of 103, 102, 10 Hz, proving that the dielectric constant has negative values only at frequencies above one megahertz 106Hz. Also, the dielectric loss has negative values with temperature at all voltages and high frequencies. This structure also has a low dielectric loss tangent from 4 to 50 with all voltages and temperatures and high rectification ratio reach to 1200 times, and high Rj. The performance of dielectric constant, dielectric loss, and dielectric loss tangent depend on the change of frequencies and voltages. The electrical properties of this structure were examined by conventional, dv/dlnI, and the Nord and Cheung method. The ideality factor fluctuates between 3.09 and 3.29, and the barrier height is in the range of 0.56 to 0.58 at room temperature. We found similar results using different methods of measuring the electrical properties. This indicates that the structure is a promising material for preparing diodes, supercapacitor, and high storage devices.

An Unconventional Immunosensor for Biomolecule Detection via Nonspecific Gold Nanoparticle-Antibody Interactions.

Immunogold, that is, gold nanoparticles (AuNPs) conjugated with biomolecules such as antibodies and peptides, have been widely used to construct sandwiched immunosensors for biodetection. Two main challenges in these immunoassays are difficulties in finding and validating a suitable antibody, and the nonspecific interaction between the substrate and immunogold, which lowers the detection sensitivity and even causes false results. To avoid these issues, we took advantage of the nonspecific interaction between AuNPs and capture antibodies and proposed a new sensing mechanism. That is, after the capture of analyte targets by the capture antibodies on the substrate, AuNPs of certain chemical functionality would preferably bind to the free capture antibodies. Consequently, the amount of deposited AuNPs will inversely depend on the concentration of the analytes. As a proof-of-concept, we designed a mass-based sensor where anti-IgG antibodies were coated on a quartz crystal microbalance substrate. After IgG was introduced, tannic acid-capped AuNPs were applied to bind with the free anti-IgG antibody molecules. A frequency change (Δf) of the quartz substrate was induced by the increased mass loading. To further amplify the loading mass, an Ag enhancer solution was added, and Ag growth was catalyzed by the bound AuNPs. The Δf response showed a concentration-dependent decrease when increasing IgG concentration with a detection limit of 2.6 ng/mL. This method relies on the nonspecific interaction between AuNPs and anti-IgG antibodies to realize sensitive detection of IgG and eliminates the use of detection antibodies. The concept is an alternative to many existing immunoassay technologies.

Abstract PO4-14-10: Circulating Tumor DNA as a Biomarker for ADCs in Metastatic Breast Cancer

Abstract Background: Breast cancer is a complex disease characterized by heterogeneity, and the analysis of circulating tumor DNA (ctDNA) holds promise for capturing this heterogeneity. Recently, ctDNA testing has been employed in clinical practice to guide targeted therapies for metastatic breast cancer, particularly in cases of hormone receptor-positive disease with mutations in PIK3CA and ESR1. This approach becomes necessary when traditional tumor biopsies are inadequate for next-generation sequencing (NGS) testing or fail to capture the full extent of the cancer's heterogeneity. Moreover, the utilization of antibody-drug conjugates (ADC) in addressing tumor heterogeneity continues to expand. However, there has been no biomarker, outside of HER2 protein expression, to predict ADC response. In this project, we test the hypothesis that ctDNA can be utilized as a biomarker to predict response to novel therapies such as ADCs. Methods: We analyzed a subset of patients from the Dallas Metastatic Breast Cancer Study comprised of patients with metastatic breast cancer (n= 109) who underwent ctDNA testing using the Tempus xF liquid biopsy ctDNA sequencing panel. This panel detects 105-genes that are known oncogenic drivers and resistance mutations. The data was collected from a single academic medical center between the initial year of ctDNA collection in 2019 and 2023. Results: Among these patients, 85 (77.9%) had hormone receptor-positive disease, 13 (11.9%) had triple-negative breast cancer, and 11 (10.0%) had HER2-positive disease (including 3 (2.75%) patients with triple-positive disease). Only 22 of these patients had tissue biopsies that underwent NGS testing. Analysis of all patients revealed that the most common gene alteration was PIK3CA, which was identified in 70 patients. Specifically, the most frequently observed alteration was PIK3CA p.545K, found in 25 patients. Table 1 further details the frequency of each gene in this subset of patients. Among the patients, 34 out of 109 (31%) received an ADC, while only 8 out of 109 (7%) received immunotherapy. Patients with CDKN2A achieved the longest progression-free survival (PFS) on an ADC, with a median PFS of 7 months, whereas patients carrying mutations in TP53, PIK3R1, PIK3CA, PTEN, NF1, BRAF, RHOA, FGFR4, KRAS, TERT, GATA3, HNF1A, FB1, STOP had median PFSs of 2 months or less. Table 2 provides additional information on the response of patients with specific mutations to ADCs. Notably, only one patient received sequential ctDNA testing, and in that case, there was a gain of TP53 p.N239S following sacituzumab govitecan administration compared to the baseline ctDNA test, followed by a gain of PIK3CA p.P449_L455del after trastuzumab deruxtecan administration. Conclusions: As we observe changes in subtypes following treatment progression, researchers are actively seeking biomarkers to better characterize real-time changes in tumor biology that can predict response and resistance to treatments. Further studies are needed to identify additional genes present in ctDNA that can provide mechanistic insights into why certain patients respond favorably to ADCs while others do not. We are currently enrolling patients for a prospective study that aims to assess baseline ctDNA levels and monitor changes in variant allele frequency following treatment with ADCs and immunotherapy. Table 2 Median PFS on ADC by Gene Citation Format: Hannah Chang, Isabela Anawate, Alyssa Low, Shao-Po Huang, Julia Maues, Christine Hodgdon, Isaac Chan. Circulating Tumor DNA as a Biomarker for ADCs in Metastatic Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-14-10.