Source Depth Research Articles

An in situ-activated and chemi-excited photooxygenation system based on G-poly(thioacetal) for Aβ1-42 aggregates.

The abnormal aggregation of Aβ proteins, inflammatory responses, and mitochondrial dysfunction have been reported as major targets in Alzheimer's disease (AD). Photooxygenation of the amyloid-β peptide (Aβ) is viewed as a promising therapeutic intervention for AD treatment. However, the limitations of the depth of the external light source passing through the brain and the toxic side effects on healthy tissues are two significant challenges in the photooxidation of Aβ aggregates. We proposed a method to initiate the chemical stimulation of Aβ1-42 aggregate oxidation through H2O2 and correct the abnormal microenvironment of the lesions by eliminating the cascading reactions of oxidative stress. The degradable G-poly(thioacetal) undergoes cascade release of cinnamaldehyde (CA) and thioacetal triggered by endogenous H2O2, with CA in turn amplifying degradation by generating more H2O2 through mitochondrial dysfunction. A series of novel photosensitizers have been prepared and synthesized for use in the photodynamic oxidation of Aβ1-42 aggregates under white light activation. The nanoparticles (BD-6-QM/NPs) self-assembled from BD-6-QM, bis[2,4,5-trichloro-6-(pentoxycarbonyl) phenyl] ester (CPPO), and G-poly(thioacetal) not only exhibit H2O2-stimulated controlled release but also can be chemically triggered by H2O2 to generate singlet oxygen to inhibit Aβ1-42 aggregates, reducing the Aβ1-42-induced neurotoxicity.

Experimental research on signal sensing of distributed acoustic sensing optical fiber based on Φ-OTDR in shallow water

The distributed acoustic sensing (DAS) technology based on phase-sensitive optical time domain reflectometry (Φ-OTDR) has been widely and well applied on land. Meanwhile, the distributed acoustic sensing optical fiber (DASF) based on Φ-OTDR, as a new type of sensor, is still in the initial stage of research, gets much attention in recent years because of its long-distance monitoring, high sensitivity, anti-electromagnetic interference, good concealment and so on. Performances of DASF in sensing different kinds of acoustic source signals were given by experiments in shallow water, which included single frequency pulse signal in the fixed position, the moving single frequency continuous pulse signal, the moving broadband signal, and the signal generated by the sailing surface target. Depth of the active sound source was changed to examine the performance of DASF in sensing signals in different depths. The specific experimental process was given, and the experimental results were processed and analyzed. Additionally, wave components of data generated from of the sailing surface vessel were explored with the time delay difference between the equivalent array elements of DASF. Results show that DASF can sense the above varieties of underwater acoustic signals well, and the physical field generated by the sailing surface vessel in shallow water include acoustic field and flow field, in which the propagation velocity of the former is faster than that of the latter.

Assessment of heavy metal distribution and bioaccumulation in soil and plants near coal mining areas: implications for environmental pollution and health risks.

Monitoring heavy metals (HMs) across source distance and depth distribution near coal mining sites is essential for preventing environmental pollution and health risks. This study investigated the distribution of selected HMs, cadmium (Cd2+), chromium (Cr2+), copper (Cu2+), manganese (Mn2+), nickel (Ni2+), lead (Pb2+), and zinc (Zn2+), in soil samples collected from ten sites (S-1-S-10) at two different depths (0-15 and 15-30 cm) and distances of 50, 100, and 200 m from a mining source. Additionally, three plant species, Prosopis spp., Justicia spp., and wheat, were collected to assess HM bioavailability and leaf accumulation. Coal mine activities' impact on soil properties and their HM associations were also explored. Results reveal HM concentrations except for Cr2+ exceeding World Health Organization (WHO) limits. In surface soil, Cd2+ (58%), Cu2+ (93%), Mn2+ (68%), Ni2+ (80%), Pb2+ (35%), and Zn2+ (88%) surpassed permissible limits. Subsurface soil also exhibited elevated Cd2+ (53%), Cu2+ (83%), Mn2+ (60%), Ni2+ (80%), Pb2+ (35%), and Zn2+ (77%). Plant species displayed varying HM levels, exceeding permissible limits, with average concentrations of 1.4, 1.34, 1.42, 4.1, 2.74, 2.0, and 1.98 mg kg-1 for Cd2+, Pb2+, Cr2+, Cu2+, Mn2+, Ni2+, and Zn2+, respectively. Bioaccumulation factors were highest in wheat, Prosopis spp., and Justicia spp. Source distance and depth distribution significantly influenced soil pH, electrical conductivity (EC), and soil organic carbon (SOC). Soil pH and EC increased with an increase in soil depth, while SOC decreased. Pearson correlation analysis revealed varying relationships between soil properties and HMs, showing a considerably negative correlation. Concentrations of HMs decreased with increasing depth and distance from mining activities, validated by regression analysis. Findings suggest crops from these soils may pose health risks for consumption.

Numerical Simulation Study of Seafloor Hydrothermal Circulation Based on HydrothermalFoam: A Case Study of the Wocan-1 Hydrothermal Field, Carlsberg Ridge, Indian Ocean

Deep-sea hydrothermal circulation plays a pivotal role in the material and energy exchange in deep-sea environments, exerting significant influence on the evolution of seawater chemistry and global climate dynamics. Based on existing data and assumptions, this study presents a numerical model tailored for the hydrothermal circulation in the Wocan-1 Hydrothermal Field, Carlsberg Ridge, Indian Ocean. The model successfully simulates the hydrothermal circulation patterns within the oceanic crust, providing detailed insights into temperature distribution, flow field structures, and elemental concentration gradients. Through data analysis of the simulation results, we inferred the depth and temperature of potential heat sources within the Wocan-1 hydrothermal field. The maximum temperature of the heat source Tmax = 823K (550 °C) and the depth of the heat source h = 1 km are possible results. To deepen understanding of the heat source’s impact on fluid temperatures, a sensitivity analysis was conducted. The findings show a positive correlation between both the heat source’s temperature and its depth with the fluid temperature at vent outlets. Regarding elemental transport, this paper offers a preliminary exploration of the kinetic processes in hydrothermal circulation and presents an empirical relationship linking elemental concentrations at the bottom to those at the vent: Cvent = 0.26 Cboundary. This study enhances current numerical models for hydrothermal vents, offering valuable insights for future work and utilization in the Wocan-1 hydrothermal field, and potentially in any other hydrothermal field.

Modeling the effect of processing parameters on temperature history in Directed Energy Deposition: an analytical and finite element approach

PurposeThe purpose of this paper is to assess the feasibility of analytical models, specifically the radial basis function method, Akbari–Ganji method and Gaussian method, in conjunction with the finite element method. The aim is to examine the impact of processing parameters on temperature history.Design/methodology/approachThrough analytical investigation and finite element simulation, this research examines the influence of processing parameters on temperature history. Simufact software with a thermomechanical approach was used for finite element simulation, while radial basis function, Akbari–Ganji and Gaussian methods were used for analytical modeling to solve the heat transfer differential equation.FindingsThe accuracy of both finite element and analytical methods was validated with about 90%. The findings revealed direct relationships between thermal conductivity (from 100 to 200), laser power (from 400 to 800 W), heat source depth (from 0.35 to 0.75) and power absorption coefficient (from 0.4 to 0.8). Increasing the values of these parameters led to higher temperature history. On the other hand, density (from 7,600 to 8,200), emission coefficient (from 0.5 to 0.7) and convective heat transfer (from 35 to 90) exhibited an inverse relationship with temperature history.Originality/valueThe application of analytical modeling, particularly the utilization of the Akbari–Ganji, radial basis functions and Gaussian methods, showcases an innovative approach to studying directed energy deposition. This analytical investigation offers an alternative to relying solely on experimental procedures, potentially saving time and resources in the optimization of DED processes.

Looking for optimal concentric ring electrodes: influence of design aspects on their performance

Concentric ring electrodes (CREs) allow improved spatial resolution, reduced crosstalk and interference, and increased bandwidth in the sensing of bioelectrical activity. A wide variety of designs have been used, but their selection is rarely well-founded. The aim of this work is to assess the implications of aspects of CRE design such as the distance between poles, their width and their maximum diameter on aspects such as the signal amplitude (and, therefore, quality), Laplacian estimation error and spatial selectivity (SS). For this purpose, a finite dimensional model of the CRE was used, and its response to the activity of an electric dipole of variable depth was simulated via finite element method modeling. Our results show that increasing the electrode size increases the error to a greater extent than the signal amplitude increases. Pole widths should be as small as possible. The middle ring of the tripolar CRE should be as far away as possible from the central disc. Tripolar CREs typically outperform bipolar CREs of the same outer diameter, significantly reducing the Laplacian estimation error and improving the SS at the cost of a small decrease in signal amplitude. Our results also show that the design of current commercial versions of CREs can be optimized. Furthermore, we propose a methodology that facilitates the selection of an adequate CRE configuration based on the specifications for CRE performance and practical aspects, such as the depth of activity sources to be recorded from and/or the maximum size of electrodes to be used. The monitoring and analysis of bioelectrical signals in a wide range of applications can benefit from the enhanced electrode design and methodology proposed in this work.

SARIKHOSOR EARTHQUAKES on March 29, 2018 with KR=13.1, Мs=5.1, I0=6 and March 7, 2019 with KR=12.1, МS=4.1, I0=5–6 (Tajikistan)

General information about the tangible earthquakes that occurred on the territory of Tajikistan in 2018–2019 and their confinement to tectonic structures is given. The most active tectonic structures during this period within which strong seismic events occurred are determined. The results of a survey of macroseismic manifestations of March 29, 2018 and March 7, 2019 earthquakes, which occurred in the eastern part of the Tajik depression, and their isoseist maps are presented. An assumption about the possible influence of two large reservoirs on the increase of the seismicity of the region is made. An analysis of the depths of earthquake sources in comparison with the geological and tectonic structures of the region is made. The difference in the depths of earthquakes, determined by different seismological services, makes it difficult to link the source of seismic events to tectonic structures and to determine their parameters.

Structure Engineered High Piezo-Photoelectronic Performance for Boosted Sono-Photodynamic Therapy.

Sono-photodynamic therapy is hindered by the limited tissue penetration depth of the external light source and the quick recombination of electron-hole owing to the random movement of charge carriers. In this study, orthorhombic ZnSnO3 quantum dots (QDs) with piezo-photoelectronic effects are successfully encapsulated in hexagonal upconversion nanoparticles (UCNPs) using a one-pot thermal decomposition method to form an all-in-one watermelon-like structured sono-photosensitizer (ZnSnO3 @UCNPs). The excited near-infrared light has high penetration depth, and the watermelon-like structure allows for full contact between the UCNPs and ZnSnO3 QDs, achieving ultrahigh Förster resonance energy transfer efficiency of up to 80.30%. Upon ultrasonic and near-infrared laser co-activation, the high temperature and pressure generated lead to the deformation of the UCNPs, thereby driving the deformation of all ZnSnO3 QDs inside the UCNPs, forming many small internal electric fields similar to isotropic electric domains. This piezoelectric effect not only increases the internal electric field intensity of the entire material but also prevents random movement and rapid recombination of charge carriers, thereby achieving satisfactory piezocatalytic performance. By combining the photodynamic effect arising from the energy transfer from UCNPs to ZnSnO3 , synergistic efficacy is realized. This study proposes a novel strategy for designing highly efficient sono-photosensitizers through structural design.

Heat supply pipeline detection based on temperature gradient data of shallow ground

Heat supply pipelines are a critical component of urban infrastructure, with numerous underground projects relying on this crucial and often concealed system. In cases where blueprints are unavailable, it is crucial to determine the precise location and depth of heat supply pipelines. One of the most straightforward methods for detecting these pipelines is measuring underground temperature. Temperature gradient data is less sensitive to environmental temperature changes for detecting shallow heat sources than temperature data. This paper presents an extension of the correlation imaging method to handle temperature gradient data. This method can accurately determine the horizontal center position and the depth of the heat source. This temperature tomographic approach is reliable and has a high resolution, as evidenced by both synthetic and field examples.

Gravity patterns and crustal architecture of the South-Central Indian Ridge at 22°-17°S: Evidence for the asymmetric ridge accretion

The present study examines the gravity-derived structural fabric and crustal structure beneath the southern portion of the Central Indian Ridge at 22°-17°S. We examined the structures using enhanced edge detection techniques like gradient amplitude of the vertical derivative (HGVD), improved horizontal tilt angle (ITDX), gradient amplitude of the NTilt (HGNTilt) and the fast sigmoid function (FSED) on synthetic examples and the gravity data of the study region. The gravity-derived lineaments describes the lineaments that are parallel to fracture zones trending in ENE-WSW, parallel to segments/major ridge axis, near circular lineaments probably depicting ascending magma sources. We estimated the depth to the gravity-derived lineaments using the tilt_depth technique, which reveals the presence of lineaments with shallow source depth range at 2.5–7 km. The south-Central Indian Ridge is characterized by numerous lineaments with random depths that shows variable spreading rates and continuous ridge jumps. The major lineament depths are rooted into the lower crust beneath the major axis and the upper mantle in the region away from it. In addition, gravity inversion of low-pass filtered Bouguer anomaly data is used to estimate the crustal thickness. The gravity inversion shows that the Moho depth varies from 5 to 14.5 km, which shows thicker crust along the principal ridge axis and thinner in the surrounding regions. The structural fabric in combination with the crustal thickness, depth of the lineaments, age of the ridge crust, earthquake data suggests discrete minor/local ridge jumps along the major ridge axis and asymmetric accretion along the ridge axis.

Method of co-seismic fault displacement estimate based on peak ground acceleration

Based on the results of the seismic hazard survey in Yunnan Province, four exceedance probabilities of peak ground acceleration were converted into earthquake magnitudes using the empirical relationship between epicentral intensity and magnitude. By using logistic regression, earthquake magnitude, source depth, cover layer thickness, and fault type were used as independent variables to calculate the probability of co-seismic displacement for different earthquake magnitudes. Using the magnitude-displacement empirical model in the southwestern region of China, horizontal and vertical displacements were obtained with a 95 % confidence level. The results show that all Holocene faults have the ability to produce surface displacement, but from the perspective of probabilistic hazard, the probability of surface rupture in the short term is low, while the probability of surface rupture for each fault significantly increases over a long time scale. Buildings with different service lives should adopt different avoidance strategies, and buildings with shorter service lives (<50a) can consider not avoiding active faults.

Not another hillshade: alternatives which improve visualizations of bathymetric data

Increasing awareness of the importance of effective communication of scientific results and concepts, and the need for more accurate mapping and increased feature visibility led to the development of novel approaches to visualization of high-resolution elevation data. While new approaches have routinely been adopted for land elevation data, this does not seem to be the case for the offshore and submerged terrestrial realms. We test the suitability of algorithms provided by the freely-available and user-friendly Relief Visualization Toolbox (RVT) software package for visualizing bathymetric data. We examine the algorithms optimal for visualizing the general bathymetry of a study area, as well as for highlighting specific morphological shapes that are common on the sea-, lake- and riverbed. We show that these algorithms surpass the more conventional analytical hillshading in providing visualizations of bathymetric data richer in details, and foremost, providing a better overview of the morphological features of the studied areas. We demonstrate that the algorithms are efficient regardless of the source data type, depth range, resolution, geographic, and geological setting. The summary of our results and observations can serve as a reference for future users of RVT for displaying bathymetric data.

How Have Formal Firms Recovered From the Pandemic? Insights From Survey and Tax Administrative Data in Zambia

Abstract This paper examines how formal firms have been impacted by and recovered from the COVID-19 pandemic, by drawing on two distinct but complementary data sources. This is the first attempt to use both survey and tax administrative data to measure the impact of the pandemic in a developing country. The findings of three rounds of follow-up surveys to a standard World Bank Enterprise Survey completed immediately before the pandemic are compared to the universe of value-added tax and personal income tax returns filed by firms in Zambia. Despite substantial differences in the breadth and depth of these data sources, they show a very similar pattern. The sales of formal firms recovered from the pandemic far more strongly than their employment levels. By July 2021, both the survey and tax administrative data show that most firms experienced a complete recovery in sales, while levels of employment worsened throughout the pandemic for many firms. The tax administrative data show that even two and a half years following the start of the pandemic, employment in formal firms remained well below pre-pandemic levels. The key insight that emerges from this analysis is that formal firms appear to have adjusted their operations in a way that reduced their need for as much labor to achieve the same (or higher) level of sales. As such in response to an unprecedented shock, productivity gains within formal firms were possible through the shredding of somewhat unproductive labor inputs, which can often be more challenging in a stable setting.

Particle Filtering for Source Depth and Water Depth Joint Tracking in Shallow Water

Environmental mismatch degrades the performance of source localization and tracking methods in shallow water. One solution is to estimate source parameters and the key environmental parameters simultaneously from the acoustic data. In this paper, an unconventional approach of joint tracking source depth and water depth parameters by a particle filter is proposed. This approach is free of prior environmental knowledge and numerical calculation of any forward model. First, a state-space model based on modal nature behavior is established driving the shallow-water propagation, instead of modeling in time or space, as was done previous works. Subsequently, particle filtering is employed for joint tracking, in which the evolution with mode-order of vertical wavenumbers and the relationship between state parameters and beam-wavenumber outputs transformed from the data are exploited. Final, the particle smoother reduces the uncertainty of state parameters at initial steps, and improves the overall tracking accuracy. Our approach is demonstrated using simulated data in an ideal waveguide and applied to shallow-water SWellEx-96 experimental data to substantiate its superior performance.

Source depth estimation based on Gaussian processes using a deep vertical line array

For a bottom-moored vertical line array in the direct arrival zone, interference patterns have been used for source depth estimation. The interference pattern shows periodic modulation. Its period is directly related to the source depth, source frequency, and grazing angle. The performance degrades when the interference pattern is corrupted by ambient noise and other interferers. In this paper, broadband interference fringes are modeled as Gaussian processes (GPs) with a periodic kernel and are denoised using Gaussian process regression. The source depth is estimated based on the periodicity of the denoised interference fringe. Simulation results demonstrate that compared to the Fourier transform-based method, GPs provide a better performance with a low signal-to-noise ratio and a better ability to estimate the depth of a very shallow source. Real data recorded by a 105 m-aperture vertical array also verify the performance of GPs on source depth estimation without knowing the ocean environment.

Identification of Geothermal Distribution in The Banyu Biru Hot Water Source using The Magnetic Method

<p class="Abstract">The geothermal phenomenon in Banyu Biru hot springs in Gondangwetan Village, Jatikalen District, Nganjuk Regency, has the potential to be developed into a tourist spot and an alternative renewable energy source that is environmentally friendly; for example, a geothermal power plant. So it is necessary to know the distribution of geothermal reservoirs and how much potential energy is contained. This research aims to determine the distribution of geothermal energy in the research area and its geological structure. This study used the Magnetic Method for secondary data obtained from NOAA satellite data. Data acquisition with an area of 2000 meters x 2000 meters obtained 100 data with a spacing of 200 meters. Based on research results, geothermal bursts have a low anomaly value of -50 nT to 25 nT. The low anomaly distribution can be used to determine the geothermal distribution in the area, assuming that areas with the same anomaly value indicate the presence of geothermal energy. The geology of the study area has five layers, namely: Topsoil (soil) has a susceptibility value of 0.0000377 SI, Alluvium has a susceptibility value of 0.00144513 SI, Tufan Clay has a susceptibility value of 0.00692407 SI, Limestone Tuff has a susceptibility value of 0.125713399 SI and Breccia (Andesite and Basalt) has a susceptibility value 0.0126292 SI. The depth of the geothermal source in the study area is ± 250 meters below the surface.</p>

Studying the influence of cold-core mesoscale ocean eddies on sound propagation based on the parabolic equation method

Mesoscale vorticity is an important factor that affects the non-uniform horizontal and vertical distribution of hydrologic elements in the ocean. In this paper, temperature and salinity data from measured mesoscale cold-core eddies during a voyage within a certain sea area are studied, and a synchronous sound field test was conducted on the mesoscale vorticity. Based on the temperature and salinity data, the parabolic equation (PE) method was selected to predict the acoustic field, and the results were compared with the measured propagation loss data of the acoustic field to verify the accuracy and effectiveness of the PE model. The underwater sound propagation characteristics in the mesoscale cold-core eddy environment were then analyzed using the temperature and salinity data retrieved from the voyage. It was found that the convergence area of the acoustic field gradually dispersed with an increase in the depth of the sound source. In a mesoscale eddy environment, when sound waves propagate from inside to outside the eddy, the presence of a cold-core eddy causes the convergence area to shift toward the edge of the eddy, and the deviation gradually decreases with an increase in the depth of the sound source.

Sources depth estimation for a tonal source by matching the interference structure in the arrival angle domain.

A publication by McCargar and Zurk [J. Acoust. Soc. Am. 133(4), EL320-EL325 (2013)] introduced a passive source depth estimation method for a moving tonal source with a vertical line array (VLA), utilizing the depth-dependent modulation in the arrival angle domain caused by the interference between the direct and surface-reflected acoustic arrivals. Under the isovelocity approximation, this method can estimate the depth of sources at close ranges, but the depth estimation error will increase with the increase in source range, as the impact of the sound speed profile on sound propagation is ignored. This paper presents a theoretical formula for calculating the modeled interference structure in the arrival angle domain with the knowledge of the sound speed profile. By matching the measured interference structure obtained from the beamforming of the acoustic data received by the VLA with the modeled structure under different assumed source depths, the tonal source depth estimation is achieved, even for sources at the remote part of the direct arrival zone. The performance of this method is verified by simulation data, as well as experimental data radiated from a towed source and a non-cooperative passing ship.

Constraining the Structure under Lunar Impact Basins with Gravity

The lunar gravity field is used to estimate and constrain the depth of mass anomalies under 19 major lunar impact basins. We use radial gravitational spectra, consisting of accelerations computed either per spherical harmonic degree or cumulatively, at surface locations to obtain the distribution of the gravity signal with spherical harmonic degree and, by implication, to the likely depth below the surface. The results provide estimates for the maximum likely depths of the primary component to the mass anomalies under 19 basins. We find that the maximum depths of the primary source of mascon gravity on the lunar nearside are deeper than the depths for those on the farside when South Pole–Aitken (SPA) is excluded. All basin mass anomalies on the lunar nearside are in the mantle. The maximum depth of the primary source of the mass anomalies is <80 km, with the exception of SPA, whose dominant mass signature lies at a maximum depth of >200 km beneath the surface. The upper 20 km under all basins is largely devoid of anomalies, reflecting predominantly mixing and relaxation associated with impact melt combined with ejecta fallback, as well as homogenization associated with post-basin formation impact bombardment. Except for SPA, all basin anomalies merge with the deep interior at ∼150 km or below, indicating the depth penetration of disruption of the density structure of the lunar interior associated with impact bombardment.

Determination of thermal structure of the crust beneath the Gongola Basin, Upper Benue Trough, Nigeria

Geothermal energy resources have been established globally to be among the sustainable and environmentally harmless means of energy generation. The data for this study came from the Earth Magnetic Anomaly Grid 2 version 3 (EMAG2V3). It was acquired at a flying elevation of 4 km above the ellipsoid and has a resolution of 2-arc minutes (3.66 km). This research aim to study the thermal structure of the crust beneath the Gongola Basin so as to determine the heat flow, geothermal gradient and the Curie point depth. In this study, the creation of an air satellite magnetic map of the Gongola Basin is accomplished through the use of a fractal magnetization approach. However, Curie point depth (commonly known as bottom most of magnetic sources depth) measure the distance between two points in space, depth to bottom magnetic source (DBMS). Geothermal characteristics of the area was evaluated using Oasis Montaj. So the earth magnetic field is utilized to determine the depth of anomalous sources that ranges from few meters to tens of kilometers. The top depth ranges from 3.4465km to 10.942km, the centroid depth ranges from 14.045km to 31.338km, the geothermal gradient ranges from 10.2566Oc/km to 23.4445 Oc/km and the heat flow ranges from 25.6415mW/m2 to 58.84 mW/m2. The study identify a point (11°63E, 10°12N) with optimal values (26.44OC/km, 66.11mW/m2) at a distance 21.9km which is above the typical optimal values obtained in stable continental craton as obtainable in African plate.