Sampling Density Research Articles

Experimental study on CO2 sequestration performance of alkali activated fly ash and ground granulated blast furnace slag based foam concrete

In an effort to reduce the emission level of carbon dioxide (CO2) from metallurgical, thermal, cement burning and other enterprises, an innovative solution is proposed in this study, which aims to sequester CO2 with alkali activated fly ash (FA) and ground granulated blast furnace slag (GGBFS) based foam concrete. The fluidity of alkali activated foam concrete (AAFC) fresh paste, dry density and compressive strength after hardening, micro-pore structure, carbonation products and CO2 sequestration capacity were comprehensively explored. The experimental findings indicated that the fluidity of AAFC slurry was almost unaffected by the content of foaming agent hydrogen peroxide (H2O2). When the H2O2 content ranges between 1 % and 3 %, the dry density of uncarbonated AAFC ranges approximately 752.3–365.2 kg/m3, and the compressive strength of carbonated AAFC ranges about 1.01–0.21 MPa. Accelerated carbonation increased the dry density of uncarbonated AAFC samples. The porous structure of AAFC facilitated CO2 gas penetration into the matrix, leading to rapid carbonation. When the H2O2 content was 1 %, the compressive strength of fully carbonated AAFC was lower than that of non-carbonated AAFC; however, when the H2O2 content exceeded 1.5 %, the trend in compressive strength reversed. The carbonation kinetics of AAFC demonstrated a linear relationship with the square root of carbonation time, and the carbonation coefficient increases proportionally with H2O2 content. The porosity of AAFC increased from 61.05 % to 71.51 % as the H2O2 content increased from 1 % to 2.5 %. The main pore size distribution range of AAFC was 30–400 µm and 5–50 nm. Accelerated carbonation minimally impacted the total porosity of AAFC but transformed certain large pores into capillary pores. Accelerated carbonation would generate calcite, aragonite, vaterite and additional amorphous phases. The maximum carbon sequestration capacity of AAFC, as determined in this study, reached 26.41 kg/m3, indicating significant potential for CO2 sequestration.

Development of binders based on the СаО–Fe2O3 system

The object of research is the processes of structure formation and modeling of the properties of a specialized binder. The development of new binding materials based on production waste with high early strength indicators could make it possible to speed up construction period and is one of the urgent tasks at present. This study focused on the creation of binders based on the СаО–Fe2O3 system. The developed binder of the СаО–Fe2O3 system has the following composition: limestone – 26 %; red slime – 74 %, which has a dense fine-porous structure and high early strength indicators – 22.5 MPa with a density of 1960 kg/m3. There is also an increase in the average density of samples annealed at a temperature of 1200 ℃ for 60 minutes, ground and mixed with water, in comparison with samples fired at 1100 ℃ for 60 minutes, by 500 kg/m3, due to new formations. The prospect of using modified composite binders with special functional properties has been substantiated. The use of production waste based on the СаО-Fe2O3 system could make it possible to obtain materials with high physical and mechanical properties, which makes them promising for application in various areas of the construction industry. The development of such binders will help reduce the environmental impact of the construction industry, owing to the use of affordable and effective components. This approach will not only contribute to the improvement of the quality of building materials but also help reduce the ecological burden on the environment by using alternative resources and industrial waste. The developed binder could be used for the development of solutions for 3d printing, as well as repair of concrete coatings

Accelerated Singular Spectrum Analysis and Machine Learning to investigate wood machining acoustics

The use of monitoring in manufacturing has increased the necessity for effective signal pre-processing methods to remove redundant data. Singular Spectrum Analysis (SSA) can decompose signals and time-series data into summable and physically interpretable reconstructed components. The high computational complexity has impeded the popularity of this method, as it could only be used for small datasets. In this study, significant work was put into the acceleration of SSA to enable the decomposition of acoustic emissions and airborne sound signals collected by monitoring wood machining. Important computational improvements were highlighted by benchmarking the accelerated SSA against the classical approach. Further results showed that the combination of SSA and Machine Learning enhanced the accuracy of predicting surface roughness (RSSA2=0.96 | RRAW2=0.89) and sample density (RSSA2=0.93 | RRAW2=0.88), while also improving the classification of cutting speeds (ACCSSA=100% | ACCRAW=86.34%) and wood species (ACCSSA=93.12% | ACCRAW=89.39%). The interpretation of the results showed that SSA enabled the selective filtering of redundant information from the monitored acoustics.

Applications and challenges of digital soil mapping in Africa

The mapping of soils in Africa is at least a century old. We currently have access to various maps depicting mapping units locally and for the continent. In the past two decades, there has been a growing interest in alternatives for generating soil maps through digital soil mapping (DSM) techniques. There are, however, numerous challenges pertaining to the implementation of DSM in Africa, such as the unavailability of appropriate covariates, age and positional error in the measurements, low sampling density, and spatial clustering of the soil data used to fit and validate the models. This review aims to investigate the current state of DSM in Africa, identify challenges specific to implementing DSM in Africa and the ways it has been solved in the literature. We found that nearly half of African countries had an existing digital soil map covering either a local or national area, and that most studies were performed at a local extent. Soil carbon was the most common property under study, whereas soil hydraulic variables were seldom reported. Nearly all studies performed mapping for the topsoil up to 30 cm and calculated validation statistics using existing datasets but without collecting a post-mapping probability sample. Few studies (i.e., 11%) reported an estimate of map uncertainty. Half of the studies had in mind a downstream application (e.g., soil fertility assessment) in the map generation. We further correlated the area of study and sampling density and found a strong negative relationship. About 30% of the studies relied on legacy soil datasets and had a lack of sufficient spatial coverage of their area of study. From this review, we highlight some research opportunities and suggest improvements in the current methodologies. Future research should focus on capacity building in DSM, new data collection, and legacy data rescue. New initiatives, that should be initiated and led from within the continent, could support the long-term monitoring of soils and updating of soil information systems while ensuring their contextualised usability. This pairs with better delivery of existing DSM studies to stakeholders and the generation of a value-added proposition to governmental institutions.

Strength and Plasticity Synergistic Enhancement Mechanism for AZ31B Magnesium Alloy Using Electrically Assisted Electromagnetic Forming

Few independent slip system causes poor formability of magnetic alloys at room temperature. Electromagnetic forming (EMF) is a high‐rate forming method, which improves formability of magnetic alloy. However, conventional EMF weakens energy utilization, and reduces strength and plasticity of formed parts. In this work, a novel electrical assisted electromagnetic forming (EAEMF) is proposed to improve energy utiization and properties of AZ31B alloy. nergy utilization of EAEMF is 100% higher than that of EMF under same height limit, which is due to the greater temperature and electromagnetic force acting on the sheet during EAEMF. Moreover, average tensile strength, yield strength, and elongation of the EAEMF specimen are 7.5%, 6.7%, and 50% higher than those of the EMF‐produced sample, respectively. This is because EAEMF promotes grain refinement, induces more twins and dislocations, which is beneficial for enhancing strength and plasticity. Particularly, twin density of EAEMF sample increased by 70%, grain size decreased by 26.6% owing to dynamic recrystallization. In addition, EAEMF weakened basal texture, increased deformation region and more uniform plastic deformation, provided more interfaces to accommodate disocations, which ensured the increase of plasticity. Therefore, this study proves the feasibility and superiority of EAEMF, providing new prospect for improving property of magnesium alloy parts.

Soil cover on complex glacial terrain and challenges for large-scale soil mapping using the World Reference Base (WRB) classification system

In conditions of complex glacial topography, large-scale soil mapping (1:10 000) according to the World reference base for soil resources (WRB) 2022 classification faces significant challenges. High diversity of reference soil groups (RSG) and qualifiers can be found in a small area, and this diversity is not related to the influence of a single but rather to a set of soil-forming factors. As a part of the study, the classification of soils on postglacial landscape was conducted using the WRB 2022 classification system. The analysis was focused on examining relationships between RSG and qualifiers, and also with type of geological deposits, location on the terrain, human activities (drainage of agricultural land, soil tillage and erosion). Survey showed that, in a relatively small area, soil cover consisted of WRB RSG such as Luvisols, Retisols, Regosols, Stagnosols, Gleysols Phaeozems, Planosols, Podzols, Histosols and Anthrosols, with the respective sets of qualifiers. Soils corresponding to the Anthrosol RSG were formed during the construction of a drainage system by burying the former soil with deeper material and later by translocation of colluvium by soil erosion. In the complex glacial topography, the distribution of RSG and their qualifiers is specific, which poses a number of challenges for soil mapping. The study confirmed the possibility of WRB classification for large-scale mapping of agricultural soils on postglacial landscape at the RSG level. The use of qualifiers for definition of mapping units in similar conditions of complex terrain and geological deposits (when mapping on a scale of 1:10 000) is possible only by increasing sampling density.

Electronegativity, susceptibility, and radiation shielding features of thulium reinforced barium-cadmium-lithium-borate glasses

The chemical composition of the following glass system 75Li2B4O7-10CdO-(15-x)BaO- 𝑥𝑥Tm2O3 (0 ≤ 𝑥𝑥 ≤ 2) mol.% has been fabricated using a traditional melt quenching procedure. The density of the synthesis samples has been measured and it enhanced with the rising Tm2O3 content. All the fabricated specimens form glass and the amorphous state have been confirmed the XRD. The spectroscopic investigation indicates an increase in the energy gap from 3.08 to 3.25 eV with increasing Tm2O3 concentrations. The refractive index, basicity and static and infinity of dielectric constant were taken place of present investigated. The ultrasonic velocities of the prepared glasses are increased. Consequently, the elastic modulus of glasses has been enhanced. MCNP5, XCOM, and Phy-X/PSD code were used to characterize the efficiency of the fabricated glass against gamma radiation. Indeed, an increase in Tm2O3 content in samples correlated with an increase in MAC values. Consequently, the gamma-radiation attenuation rate of the samples was enhanced by the addition of Tm2O3, and the protective qualities were improved.

AutoSamp: Autoencoding k-space Sampling via Variational Information Maximization for 3D MRI.

Accelerated MRI protocols routinely involve a predefined sampling pattern that undersamples the k-space. Finding an optimal pattern can enhance the reconstruction quality, however this optimization is a challenging task. To address this challenge, we introduce a novel deep learning framework, AutoSamp, based on variational information maximization that enables joint optimization of sampling pattern and reconstruction of MRI scans. We represent the encoder as a non-uniform Fast Fourier Transform that allows continuous optimization of k-space sample locations on a non-Cartesian plane, and the decoder as a deep reconstruction network. Experiments on public 3D acquired MRI datasets show improved reconstruction quality of the proposed AutoSamp method over the prevailing variable density and variable density Poisson disc sampling for both compressed sensing and deep learning reconstructions. We demonstrate that our data-driven sampling optimization method achieves 4.4dB, 2.0dB, 0.75dB, 0.7dB PSNR improvements over reconstruction with Poisson Disc masks for acceleration factors of R = 5, 10, 15, 25, respectively. Prospectively accelerated acquisitions with 3D FSE sequences using our optimized sampling patterns exhibit improved image quality and sharpness. Furthermore, we analyze the characteristics of the learned sampling patterns with respect to changes in acceleration factor, measurement noise, underlying anatomy, and coil sensitivities. We show that all these factors contribute to the optimization result by affecting the sampling density, k-space coverage and point spread functions of the learned sampling patterns.

Impact of doping on MgB2 superconductors: A comprehensive review

This review introduces fresh insights into the ongoing discussion on doping in the MgB2 superconductor compound, enriching the comparative analysis with previous reviews. Its primary objective is to succinctly summarize and enhance comprehension regarding the influence of doping on the superconducting properties of MgB2. It delves into various aspects, including the impact on the superconducting transition temperature (Tc) and the critical current density (Jc) of the doped samples, while also shedding light on the diverse synthesis methodologies employed by different research laboratories. Throughout the review, the doping agents under scrutiny encompass a wide array, ranging from Li and Be to Bi and Pb. The properties are compared with those undoped samples crafted by the authors of each publication. This review catalogs a range of cited doping agents, including H, Li, Be, C, C15H12O2, diamond, graphene oxide, NaCl, Na2CO3, Mg, Al, Si, K2CO3, CaH2, CaCO3, Sc, Ti, Ni, Cu, Zn, MgGa, GeO2, Se, Rb2CO3, Rh, Pd, Ag, In, Sn, Sb2O3, Te, Cs2CO3, LaB6, La2O3, CeO2, Pr6O11, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Tb4O7, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, Os, Ir, Pt, Hg, Pb, and Bi. Notably, doping with Be, Na2CO3, C, Al, Rb2CO3, Cs2CO3, Hg and Pb impacts mesh parameters through either Mg or B substitution. Conversely doping with Li, CaH2, Cu, Ag, La2O3, CeO2, Pr6O11, Nd2O3, Gd2O3, Tb4O7, Dy2O3, Ho2O3, Er2O3, Tm2O3, Lu2O3, GeO2, Rh, In, Sb2O3, and Pt exhibits minimal impact on Tc. Moreover, Jc can be substantially enhanced by adding C, Zn, Ag, or Sb2O3. Remarkably, the incorporation of Pd or Pt has shown a substantial increase in Jc with a remarkable improvement of +328 % and +614 % respectively observed at 2 T and 20 K. Doping with rare earth elements such as La2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, and Ho2O3 resulted in extraordinary improvement in the value of the critical current density at 20 K under specific conditions, within a range of 0–4 T.

Meta Shack–Hartmann wavefront sensor with large sampling density and large angular field of view: phase imaging of complex objects

Shack–Hartmann wavefront sensors measure the local slopes of an incoming wavefront based on the displacement of focal spots created by a lenslet array, serving as key components for adaptive optics for astronomical and biomedical imaging. Traditionally, the challenges in increasing the density and the curvature of the lenslet have limited the use of such wavefront sensors in characterizing slowly varying wavefront structures. Here, we develop a metasurface-enhanced Shack–Hartmann wavefront sensor (meta SHWFS) to break this limit, considering the interplay between the lenslet parameters and the performance of SHWFS. We experimentally validate the meta SHWFS with a sampling density of 5963 per mm2 and a maximum acceptance angle of 8° which outperforms the traditional SFWFS by an order of magnitude. Furthermore, to the best of our knowledge, we demonstrate the first use of a wavefront sensing scheme in single-shot phase imaging of highly complex patterns, including biological tissue patterns. The proposed approach opens up new opportunities in incorporating exceptional light manipulation capabilities of the metasurface platform in complex wavefront characterization.

Electromagnetic tomography measuring bench for estimating the density of materials

In the laboratory, the density of pavement cores (cylindrical samples of hot mix asphalt (HMA) material taken from roads) is assessed using an electromagnetic (EM) bench consisting of two ultra-wideband (UWB) Vivaldi antennas and a vector network analyser (VNA). The main objective is to replace the nuclear gauge system currently used in the laboratory as the standard method for this purpose. Firstly, specific antipodal Vivaldi antennas have been adapted from the literature. Their dimensions are 7 × 7 cm with a bandwidth [1.5–15 GHz]. Secondly, a tomographic approach is compared with an analytical solution and a Finite-Difference Time Domain (FDTD) simulation, based on a time-domain estimation of the dielectric under test (DUT) with a single transmitter/receiver configuration. A laboratory validation is presented and the adapted antennas as well as the time domain approach show acceptable results for assessing the dielectric constant on known materials. Finally, to show that the proposed EM bench is a promising non-ionizing solution, the density or equivalent compactness of HMA cylindrical samples is estimated and compared with nuclear gauge results.

Fast and motion-robust saturation transfer MRI with inherent B0 correction using rosette trajectories and compressed sensing.

To implement rosette readout trajectories with compressed sensing reconstruction for fast and motion-robust CEST and magnetization transfer contrast imaging with inherent correction of B0 inhomogeneity. A pulse sequence was developed for fast saturation transfer imaging using a stack of rosette trajectories with a higher sampling density near the k-space center. Each rosette lobe was segmented into two halves to generate dual-echo images. B0 inhomogeneities were estimated using the phase difference between the images and corrected subsequently. The rosette-based imaging was evaluated in comparison to a fully sampled Cartesian trajectory and demonstrated on CEST phantoms (creatine solutions and egg white) and healthy volunteers at 3 T. Compared with the conventional Cartesian acquisition, compressed sensing reconstructed rosette images provided image quality with overall higher contrast-to-noise ratio and significantly faster readout time. Accurate B0 map estimation was achieved from the rosette acquisition with a negligible bias of 0.01 Hz between the rosette and dual-echo Cartesian gradient echo B0 maps, using the latter as ground truth. The water-saturation spectra (Z-spectra) and amide proton transfer weighted signals obtained from the rosette-based sequence were well preserved compared with the fully sampled data, both in the phantom and human studies. Fast, motion-robust, and inherent B0-corrected CEST and magnetization transfer contrast imaging using rosette trajectories could improve subject comfort and compliance, contrast-to-noise ratio, and provide inherent B0 homogeneity information. This work is expected to significantly accelerate the translation of CEST-MRI into a robust, clinically viable approach.

Improvement of the Evaluation of Seismic Risk in Fault Areas by Lidar-Derived Geophysical Data

This study aimed to improve the methods of assessing seismic risk in fault zones based on lidar data in geophysics. The research highlighted this by comparing the newly developed fault maps with the usual methods of fault mapping and how lidar technology developed high-resolution 3D mapping. We conducted mobile and terrestrial LIDAR surveys to produce DEMs and study the attributes of the fault zones. The technique involved mobile lidar systems with different specifications of emitted transmission rate: 45 000 m/s to 52, 100m/s pulse repetition: 190, 000 Hz–220, 000 Hz; and point density: 10223 points/m2 to 14567 points/m2. Terrestrial lidar surveys used scanner heights of 1. 500-1. 700m and obtained the horizontal and vertical sampling density, ranging from 240,456 to 315,678 points per square meter. We used LAStools, Arc GIS, and QISIS software to filter, classify, and visualize the data processing. e applied interpolation techniques such as IDW, Kriging, Spline, and Natural Neighbors to generate DEMs. Research outcomes identified 15 different fault segments with lengths varying from 10. 000-20. 000 km, along with maximum displacements of 0. 987-4. 567 m, and average slip rates of 3. 456-7. 890 mm/year. The most extended fault segment altogether was FS05, which was 20. 000 km with a maximum bidding distance of 4. 567 m and a 7. 890 mm/year slip rate. We discovered that the proposed method successfully filtered out noise points from lidar data, with the noise points varying between 0.111-0.266 million. We created DEMs with vertical rms errors ranging from 0.045-0.050 m. The study revealed that lidar technology offers accurate and dense geospatial data, essential for discriminating between fault zones. This approach dramatically improves seismic hazard analysis and the identification of the best ways to minimize risks. These are increasing lidar surveys in other seismically active regions, using multiple data sources for analysis, and deploying constant surveys in high-risk fault line regions to increase consistency in detecting surface changes and tectonic activity.

Isotopic distribution of bioavailable Sr, Nd, and Pb in Chungcheongbuk-do Province, Korea

BackgroundMapping the distribution of bioavailable isotope ratios across landscapes serves as an efficient geochemical tool for delineating the origins and migration trajectories of humans and animals. Chungcheongbuk-do Province in central Korea, known for its geological diversity and inland location isolated from coastal influences, provides an ideal area to study the contributions of geological and environmental factors to the isotope landscape (isoscape). This study analyzed the distribution of bioavailable Sr, Nd, and Pb isotopes in the province using plant and soil data obtained in this study and from previous works.FindingsChungcheongbuk-do features diverse geological elements, including Precambrian basement, Paleozoic metasedimentary rocks, and Mesozoic granitoids and volcano-sedimentary sequences. The 87Sr/86Sr ratios of bulk soil samples from 44 sites primarily range from 0.781 to 0.706, with two ratios exceeding 0.9 originating from Precambrian basement and Cretaceous granitoid areas. Fractions of soils treated with 1 M ammonium nitrate and acetic acid exhibit indistinguishable 87Sr/86Sr ratios (R2 = 0.99, except for one point), spanning from 0.804 to 0.707. Plant 87Sr/86Sr ratios demonstrate a robust positive correlation with leachate ratios (for ammonium nitrate data, (87Sr/86Sr)plant = 0.938 × (87Sr/86Sr)leachate + 0.045, R2 = 0.98). The εNd values of bulk soils from Precambrian basement areas (–18 to –30) plot against Sm/Nd ratios around the reference line corresponding to 3 Ga, while other bulk soil samples (εNd = –1 to –21) align with a younger (~ 2 Ga) reference line. Plant εNd values, ranging from –4 to –24, exhibit a prominent positive correlation with ammonium nitrate leachates (plant εNd = 0.77 × leachate εNd – 3.83, R2 = 0.89). Plant samples do not show consistent variation between 87Sr/86Sr and εNd. The 206Pb/204Pb and 207Pb/204Pb ratios of bulk soils show a ~ 2 Ga trend, typical for Korean basement rocks. The Pb isotopic ratios of ammonium nitrate and acetic acid leachates match perfectly with each other (R2 = 0.99). The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of plant samples vary narrowly (19.2–17.9; 15.8–15.5; 39.0–38.0) and are distinctly different from those of bulk soils (24.4–17.9; 16.5–15.6; 42.5–37.9) and their leachates (23.1–17.7; 16.2–15.6; 41.0–38.1). Plant and soil data from this study and previous works were used to construct Sr and Nd isoscapes, employing interpolation models based on inverse distance weighting, simple kriging, empirical Bayesian kriging, and geology and topography-considered empirical Bayesian kriging regression prediction. These maps await validation through analysis of additional archives.ConclusionsThe isotope data obtained in this study highlight a strong geological control over bioavailable Sr and Nd, in contrast to a dominant environmental influence on bioavailable Pb. The Sr and Nd isoscapes presented here are potentially valuable for addressing archaeological or forensic inquiries in their current state. Nevertheless, the maps would benefit from additional refinement with increased sample density and enhanced interpolation models.

Processing correlations of laser direct energy deposited Inconel718 based on multi-field numerical simulation

Laser direct energy deposited (LDED) Inconel718 always have problems of non-uniform temperature distribution because of the complex flow of molten pool and layer-by-layer fabrication characterization which directly affected the microstructure and mechanical properties of materials. In this work, Inconel718 revealed a refined grains and a weave structure exhibiting excellent mechanical properties which were superior to those of the conventional casting process were successfully fabricated by adopt a high-precision and intelligent coaxial powder feeding system during the LDED processing. Moreover, based on multi-field numerical simulation method, a two-phase flow model and a transient thermal mechanical deformation model were established to simulate the LDED processing, while takes into account the evaporated mass loss of the inconel718 alloy. The morphology prediction of laser directed energy deposition by multi-physics numerical simulation, the relationship among the laser process parameters, i.e., the laser power, scanning speed and the amount of powder feeding, the temperature filed and the microstructure and mechanical properties of Inconel718 alloy during LDED were investigated and established. The simulated results consistent well with the experimental results. Results shown that the relative density of sample was sensitive to the laser power, the precision and stability of the powder feeding rate. With increasing laser power, the grain size of Inconel718 is refined, and the microhardness and tensile properties of the materials increased. The optimized LDED processing parameters were determined. Evaluating the mechanical properties of the materials LDEDed at a laser power of 600W and a scanning speed of 8.5mms-1 exhibited a high tensile strength of 944±5 MPa and a good elongation of 29 ± 0.5 %. This work suggests that the processing parameters can be optimized to prepare densified materials with excellent mechanical properties.

A time window averaging method to mitigate the impact of shell growth trends on Tridacna δ18O records

Tridacna shells have become valuable archives for high-resolution paleoclimate reconstructions due to their daily-to-annual bands. The δ18O, influenced by temperature and salinity, serves as a key geochemical proxy for Tridacna. Traditionally, linear interpolation has been the go-to method for creating evenly spaced Tridacna δ18O timeseries. However, the accuracy of this method can be influenced by the prominent negative shell growth trends. Given that Tridacna shells exhibit significantly faster growth rates during the juvenile stage than in adulthood, constant sampling intervals may lead to overly dense sampling during the juvenile phase, which could potentially introduce errors in the linearly interpolated Tridacna δ18O record. In this study, we proposed a time window averaging method to mitigate the influence of growth trends in Tridacna δ18O records from the northern South China Sea (SCS). The time window averaging method calculates the average of measured Tridacna δ18O data within a time window, whose length is determined by the sampling resolution for each year and the expected temporal resolution. Pseudo-Tridacna experiments, using the newly developed proxy system model for Tridacna δ18O, were conducted to assess the accuracy of both interpolation and averaging methods. Results indicate that the averaging method outperforms the interpolation method, especially in seasonality estimation. The pseudo-Tridacna experiments recommend employing the averaging method for monthly Tridacna δ18O records when sampling density exceeds ∼20 samples/year. Two real Tridacna δ18O records from the northern SCS demonstrate consistency with pseudo-Tridacna experiments, supporting the efficacy of the averaging method in reducing bias in Tridacna δ18O records associated with growth trends. Our results show the potential of the time window averaging method to improve Tridacna-based paleoclimate reconstructions.

All-optical method to directly measure the pressure–volume–temperature equation of state of fluids in the diamond anvil cell

We have developed a new all-optical method to directly measure the pressure–volume–temperature (PVT) equation of state (EOS) of fluids and transparent solids in the diamond anvil high pressure cell by measuring the volume of the sample chamber. Our method combines confocal microscopy and white light interference with a new analysis method, which exploits the mutual dependence of sample density and refractive index: Experimentally, the refractive index determines the measured sample chamber thickness (and therefore the measured sample volume/density), yet the sample density is by far the dominant factor in determining the variation in the refractive index with pressure. Our analysis method allows us to obtain a set of values for the density and refractive index, which are mutually consistent and agree with the experimental data within error. We have conducted proof-of-concept experiments on a variety of samples (H2O, CH4, C2H6, C3H8, KCl, and NaCl) at ambient temperature and at high temperatures up to just above 500 K. Our proof-of-concept data demonstrate that our method is able to reproduce known fluid and solid EOS within error. Furthermore, we demonstrate that our method allows us to directly and routinely measure the PVT EOS of simple fluids at GPa pressures up to, at least, 514 K (the highest temperature reached in our study). A reasonable estimation of the known sources of error in our volume determinations indicates that the error is currently ±2.7% at high temperature and that it is feasible to reduce it to ca. ±1% in future work.

A novel material for radiation detection application of zinc bismuth lithium borotellurite glass doped with Dy2O3

Radiation detection glass with the following chemical composition B2O3–TeO2–Li2O3–Bi2O3–ZnO doped with Dy2O3 where x = 0.00, 0.10, 0.50, 1.00, 1.50 and 2.00 mol%, was developed for the characterization of physical properties such as density, molar volume (Vm), and refractive index, optical absorption, luminescence, CIE's diagram, and radiation detection properties. The density and refractive index of glass samples increase with the increase of Dy2O3 composition. The optical property of glass shows eight strongest peaks from 6H15/2 centering at 263 nm (4I13/2 + 4F7/2), 298 nm (4G11/2), 357 nm (4I15/2), 803 nm (6F5/2), 897 nm (6F7/2), 1090 nm (6H7/2 + 6F9/2), 1272 nm (6F11/2 + 6H9/2) and 1671 nm (6H11/2), respectively. The emission peaks are r (4F9/2), 481 nm (6H15/2), 575 nm (6H13/2), 664 nm (6H11/2), and 751 nm (6H9/2) under excited at 453 nm (4F9/2), respectively. The excitation peaks under emission at 575 nm from 6H15/2 centering at 350 nm (6P7/2), 365 nm (4P3/2), 388 nm (4K17/2), 425 nm (4G11/2), 453 nm (4I15/2), and 471 nm (4F9/2) respectively. The study of luminescence characteristics, which includes emission, excitation, and CIE diagrams, reveals white emission bands that coincide with the CIE diagram. Furthermore, measuring the parameters of the thermoluminescence dosimeter (TLD) recorded with a heating rate of 5 °C/s in the temperature up to a maximum of 400 °C yields good results in low dose radiation detection. Based on all the results, it was determined that this glass can be a candidate for radiation detection materials in the future.

An Experimental Study on The Effect of Chemical Composition on The Strength Behaviour of Geopolymer Mortar

Abstract Sustainable development in the construction industry aims to improve the lifetime standards of present and future generations. Among industrial by-products, Ground Granulated blast Furnace Slag (GGBS) powder is employed as a cementitious material. This work investigates the properties of geopolymer binders prepared using the GGBS without conventional cement. The individual properties of the Geopolymer mortar (GPM) samples such as compressive strength and chemical composition were evaluated as per relevant IS Standards. Cubes of size (70.6×70.6×70.6) mm were cast and cured at ambient conditions for molarity 8M, 10M, and 12M with different fine aggregates, i.e., River sand, M-Sand, and GGBS. Compressive strength for 3, 7, and 28 days was evaluated. The results exhibit higher improvement in strength for 12M GPM’s with higher strength for river sand-based mixes. The chemical composition of GPM samples after 28 days of curing is determined. Essential chemical constituents such as SiO2 in 12M GPM’s considerably increased compared to 8M and 10M. The water absorption rate of samples with M-sand is greatly lowered with increasing molarity compared to those with river sand. The dry density of samples with M-sand exhibited higher improvement with increased molarity than those with river sand.

Distortionless, free-breathing, and respiratory resolved 3D diffusion weighted imaging of the abdomen.

Abdominal imaging is frequently performed with breath holds or respiratory triggering to reduce the effects of respiratory motion. Diffusion weighted sequences provide a useful clinical contrast but have prolonged scan times due to low signal-to-noise ratio (SNR), and cannot be completed in a single breath hold. Echo-planar imaging (EPI) is the most commonly used trajectory for diffusion weighted imaging but it is susceptible to off-resonance artifacts. A respiratory resolved, three-dimensional (3D) diffusion prepared sequence that obtains distortionless diffusion weighted images during free-breathing is presented. Techniques to address the myriad of challenges including: 3D shot-to-shot phase correction, respiratory binning, diffusion encoding during free-breathing, and robustness to off-resonance are described. A twice-refocused, M1-nulled diffusion preparation was combined with an RF-spoiled gradient echo readout and respiratory resolved reconstruction to obtain free-breathing diffusion weighted images in the abdomen. Cartesian sampling permits a sampling density that enables 3D shot-to-shot phase navigation and reduction of transient fat artifacts. Theoretical properties of a region-based shot rejection are described. The region-based shot rejection method was evaluated with free-breathing (normal and exaggerated breathing), and respiratory triggering. The proposed sequence was compared in vivo with multishot DW-EPI. The proposed sequence exhibits no evident distortion in vivo when compared to multishot DW-EPI, robustness to B0 and B1 field inhomogeneities, and robustness to motion from different respiratory patterns. Acquisition of distortionless, diffusion weighted images is feasible during free-breathing with a b-value of 500 s/mm2, scan time of 6 min, and a clinically viable reconstruction time.