Tracing Technique Research Articles

The Role of Gli1+ Mesenchymal Stem Cells in Osteogenesis of Craniofacial Bone.

Glioma-associated oncogene homolog 1 (Gli1) is a transcriptional activator of hedgehog (Hh) signaling that regulates target gene expression and several cellular biological processes. Cell lineage tracing techniques have highlighted Gli1 as an ideal marker for mesenchymal stem cells (MSCs) in vivo. Gli1+ MSCs are critical for the osteogenesis of the craniofacial bone; however, the regulatory mechanism by which Gli1+ MSCs mediate the bone development and tissue regeneration of craniofacial bone has not been systematically outlined. This review comprehensively elucidates the specific roles of Gli1+ MSCs in craniofacial bone osteogenesis. In addition to governing craniofacial bone development, Gli1+ MSCs are associated with the tissue repair of craniofacial bone under pathological conditions. Gli1+ MSCs promote intramembranous and endochondral ossification of the craniofacial bones, and assist the osteogenesis of the craniofacial bone by improving angiopoiesis. This review summarizes the novel role of Gli1+ MSCs in bone development and tissue repair in craniofacial bones, which offers new insights into bone regeneration therapy.

Analysis of soils, grapes, and wines for Sr isotope characterisation in Diqing Tibetan Autonomous Prefecture (China) and combining multiple elements for wine geographical traceability purposes

Determining the origin and authenticity of wine is a matter of rising interest among consumers and industry standards. The strontium isotopic ratio is regarded as an efficient technique for wine tracing. This study presents an assessment of the Sr isotope value in different matrices, including soil, grapes, and wine. Strontium isotopic maps were built using measured data. Diqing soil isotope ratios ranged between 0.714010 and 0.721999, and grape and wine isotope ratios ranged between 0.710029 and 0.718137, and 0.709508 and 0.718372, respectively. A high correlation was found between the Sr isotope ratios between of grapes and wines (R2 = 0.945), and a weak correlation was found between soil and grapes (R2 = 0.187). In general, the 87Sr/86Sr ratios of Diqing wine have a different range from those of wine from other countries. Compared to carbon isotope values, the oxygen isotope values have a wide diversity in wine from different regions. Elemental fingerprinting, light and heavy isotopes combined with discriminant analysis (DA) and random forest (RF) supported a relatively small wine geographical origin more effectively than the isotopes. This study is the first to focus on the Sr isotopes in different matrices (soil, grapes, and wine) from China and provides a data reference for tracing the provenance of wine.

Fluorescent Tracing of Dialdehyde Sodium Alginate Tanning Agent in Leather Matrix

Dialdehyde polysaccharides possess a sustainable nature and good tanning performance. However, the lack of specific detectable groups in their molecular structure results in the difficulty in the determination of the location of dialdehyde polysaccharides in leather fiber networks. In this study, dialdehyde sodium alginate (DSA) tanning agent was fluorescent labeled by 5-(4,6-dichlorotriazinyl) aminofluorescein (DTAF). The purified DTAF–DSA showed high and stable fluorescent intensity at emission wavelength of 515.2 nm when the pH was over 6.0, and the temperature was in the range of 20°C to 50°C. DTAF–DSA was used in tanning and tracked using fluorescence microscopy. Its penetration in the fiber network could be clearly visualized, and its distribution in leather differed with the molecular weight of DSA. As a result, this fluorescence tracing technique could display the mass transfer behavior of dialdehyde polysaccharide tanning agents in leather matrix, which will provide underlying data for tanning mechanism exploration.

Nitrogen loss through anaerobic ammonium oxidation coupled with ferric iron reduction in the Yellow River Wetland, Sanmenxia, China

Anaerobic ammonium oxidation coupled with iron(III) reduction (Feammox) is a recently discovered pathway of nitrogen removal. However, little is known about the pathways of N transformation via Feammox in the Yellow River wetland. In this study, the difference between Feammox in a natural wetland (site YJW) and a crop rotation wetland (site TEH) was researched using isotope tracing and metagenome techniques. The results revealed that Feammox occurred in TEH but not in YJW. The Feammox rates in the TEH samples were 0.02–0.13 mg N kg−1 d−1 in different depth intervals (0–5 cm, 5–10 cm, 10–20 cm, and 20–30 cm), and the maximum value for TEH occurred in the 5–10 cm depth interval. Iron reducing bacteria play an essential role in Feammox. Rotational tillage reduced the microbial diversity of the iron-reducing bacteria, but it increased the abundance of iron-reducing bacteria at the genus level, and the dominate iron-reducing bacteria responsible for the Feammox process were Anaeromyxobacter and Geobacter. The Feammox rate was less than the denitrification rate (0.55–1.09 mg N kg−1 d−1), an estimated nitrogen loss of 1.1–7.1 t N km−2 a−1 was associated with the Feammox in the wetland. However, the correlation between the functional genes of the iron-reducing bacteria and the rate remains unclear.

Nitrogen removal in freshwater sediments of riparian zone: N-loss pathways and environmental controls.

The riparian zone is an important location of nitrogen removal in the terrestrial and aquatic ecosystems. Many studies have focused on the nitrogen removal efficiency and one or two nitrogen removal processes in the riparian zone, and less attention has been paid to the interaction of different nitrogen transformation processes and the impact of in situ environmental conditions. The molecular biotechnology, microcosm culture experiments and 15N stable isotope tracing techniques were used in this research at the riparian zone in Weinan section of the Wei River, to reveal the nitrogen removal mechanism of riparian zone with multi-layer lithologic structure. The results showed that the nitrogen removal rate in the riparian zone was 4.14-35.19 μmol·N·kg-1·h-1. Denitrification, dissimilatory reduction to ammonium (DNRA) and anaerobic ammonium oxidation (anammox) jointly achieved the natural attenuation process of nitrogen in the riparian zone, and denitrification was the dominant process (accounting for 59.6%). High dissolved organic nitrogen and nitrate ratio (DOC:NO3-) would promote denitrification, but when the NO3- content was less than 0.06 mg/kg, DNRA would occur in preference to denitrification. Furthermore, the abundances of functional genes (norB, nirS, nrfA) and anammox bacterial 16S rRNA gene showed similar distribution patterns with the corresponding nitrogen transformation rates. Sedimentary NOX-, Fe(II), dissolved organic carbon (DOC) and the nitrogen transformation functional microbial abundance were the main factors affecting nitrogen removal in the riparian zone. Fe (II) promoted NO3- attenuation through nitrate dependent ferrous oxidation process under microbial mediation, and DOC promotes NO3- attenuation through enhancing DNRA effect. The results of this study can be used for the management of the riparian zone and the prevention and control of global nitrogen pollution.

Research of Pesticide Metabolites in Human Brain Tumor Tissues by Chemometrics-Based Gas Chromatography-Mass Spectrometry Analysis for a Hypothetical Correlation between Pesticide Exposure and Risk Factor of Central Nervous System Tumors.

Pesticides are widely used, resulting in continuing human exposure with potential health impacts. Some exposures related to agricultural works have been associated with neurological disorders. Since the 2000s, the hypothesis of the role of pesticides in the occurrence of central nervous system (CNS) tumors has been better documented in the literature. However, the etiology of childhood brain cancers still remains largely unknown. The major objective of this work was to assess the potential role of pesticide exposure as a risk factor for CNS tumors based on questionnaires and statistical analysis of information collected from patients hospitalized in the Neurosurgery Department of the Habib Bourguiba Hospital Medium in Sfax, Tunisia, during the period from January 1, 2022, to May 31, 2023. It also aimed to develop a simple and rapid analytical method by the gas chromatography-mass spectrometry technique for the research traces of pesticide metabolites in some collected human brain tumor tissues in order to more emphasize our hypothesis for such a correlation between pesticide exposure and brain tumor development. Patients with a history of high-risk exposure were selected to conduct further analysis. Chemometric methods were adapted to discern intrinsic variation between pathological and control groups and ascertain effective separation with the identification of differentially expressed metabolites accountable for such variations. Three samples revealed traces of pesticide metabolites that were mostly detected at an early age. The histopathological diagnosis was medulloblastoma for a 10-year-old child and high-grade gliomas for 27- and 35-year-old adults. The bivariate analyses (odds ratio >1 and P value <5%) confirmed the great probability of developing cancer by an exposure case. The Cox proportional hazards model revealed the risk of carcinogenicity beyond the age of 50 as a long-term effect of pesticide toxicity. Our study supports the correlation between pesticide exposure and the risk of development of human brain tumors, suggesting that preconception pesticide exposure, and possibly exposure during pregnancy, is associated with an increased childhood brain tumor risk. This hypothesis was enhanced in identifying traces of metabolites from the carbamate insecticide class known for their neurotoxicity and others from pyridazinone, organochlorines (OCs), triazole fungicide, and N-nitroso compounds known for their carcinogenicity. The 2D-OXYBLOT analysis confirmed the neurotoxicity effect of insecticides to induce oxidative damage in CNS cells. Aldicarb was implicated in brain carcinogenicity confirmed by the identification of oxime metabolites in a stress degradation study. Revealing "aziridine" metabolites from the OC class may better emphasize the theory of detecting traces of pesticide metabolites at an early age. Overall, our findings lead to the recommendation of limiting the residential use of pesticides and the support of public health policies serving this objective that we need to be vigilant in the postmarketing surveillance of human health impacts.

Slope planting patterns are superior to ditch grassing in reducing ditch erosion load to rivers: Evidenced from a five-year study in an intensive sugarcane growth watershed

Large-scale sugarcane cultivation accelerates downstream ditch erosion and causes significant soil C, N, and P losses, resulting in water pollution. The sugarcane planting pattern, i.e. the area ratio of newly planted sugarcane and perennial sugarcane, significantly affects slope soil erosion and nutrient loss. However, the influence of slope planting pattern change on downstream ditch soil erosion and pollution into the river remains unclear. We designed four experimental treatments: bare ditch-high area ratio of newly planted sugarcane (BD-H), 1-year ditch grassing-low area ratio of newly planted sugarcane (GD1-L), 2-year ditch grassing-middle area ratio of newly planted sugarcane (GD2-M), and 3-year ditch grassing-middle area ratio of newly planted sugarcane (GD3-M). Using a combination of a five-year field observation and compound-specific stable isotope (CSSI) tracing techniques, we determined the relative role of grass planting in the ditch and slope planting pattern on ditch erosion and associated nutrient loss in an intensive sugarcane cultivation watershed. The results showed that the effect of the area ratio of newly planted sugarcane on the upstream slope was significantly greater than that of grass planting on the downstream ditch erosion and river pollution. Newly planted sugarcane ratios on the upstream slope were significantly and positively correlated with the runoff in the downstream ditch (p < 0.01). The vegetation coverage, root density, and soil organic matter significantly increased with grass planting years of ditches (p < 0.01). The area ration newly planted sugarcane accounted for 57% of the variation of ditch erosion parameters (N, P, and SOC loss) (p < 0.01), and grass planting (soil organic matter, vegetation coverage, and root density) accounted for 27% of the variation of ditch erosion parameters (p < 0.05). In large-scale sugarcane-growing areas in tropical and subtropical regions, to prevent and control ditch erosion and pollution into the river, attention should be paid to vegetation restoration in the downstream ditch and the rational allocation of planting patterns in the upstream slope catchment area.

Effect of electron number densities on the radio signal propagation in an inductively coupled plasma facility

Spacecraft entering a planetary atmosphere are surrounded by a plasma layer containing high levels of ionization, due to the extreme temperatures in the shock layer. The high electron number densities cause attenuation of the electromagnetic waves emitted by the on-board antennas, leading to communication blackout for several minutes. This work presents experimental measurements of signal propagation through an ionized plasma flow. The measurements are conducted at the VKI plasma wind tunnel (Plasmatron) using conical horn antennas transmitting in the Ka-band, between 33 and 40 GHz. Testing conditions at 15, 50 and 100 mbar, and powers between 100 and 600 kW cover a broad range of the testing envelope of the Plasmatron as well as a broad range of atmospheric entry conditions. The transmitting antenna is characterized at the UPC anechoic chamber, obtaining the radiation patterns, beamwidth, and gain at the boresight direction; and an optical ray tracing technique is used to describe the electromagnetic waves propagation in the plasma flowfield inside of the Plasmatron chamber. The signal propagation measurements show clear attenuation when the signal is propagating through the plasma, varying between 2 and 15 dB depending on the testing conditions. This attenuation increases with electron number densities, which are driven by the Plasmatron power and pressure settings. Preliminary evidence of Faraday rotation effects caused by the plasma is also observed.

Membrane anatomy-based radical resection for esophageal cancer

Radical resection of gastrointestinal tumors based on the membrane anatomy theory has significantly reduced the postoperative recurrence rate and improved the surgical efficacy. However, the theory of membrane anatomy has not been widely adopted in radical surgery for esophageal cancer. Our study found that the esophagus also has a membranous anatomical structure. As a foregut organ, the esophagus also has a mesenteric structure, and there is also a fifth metastasis pathway within the esophageal mesentery for esophageal cancers. The leak and metastasis of cancer caused by destruction of the mesenteric integrity may be the fundamental reason for the high postoperative recurrence rate. Using the nano carbon and indocyanine green fluorescence tracing technique, we demonstrated the lymphatic drainage of the upper esophageal segment to the left gastric artery mesenteric lymph nodes. Therefore, in the radical resection of esophageal cancer, we used the membrane anatomy theory for guidance to completely remove the esophageal cancer, esophageal mesentery, left gastric artery and its mesentery, as well as all structures within the mesentery, preventing the spread of cancer cells through the blood vessels, lymphatic system, and mesentery, and improving the efficacy and prognosis. This article elaborates on the theoretical basis of the anatomical structure of the esophageal membrane, embryonic development, imaging, autopsy, and endoscopic observation of the structure, as well as the application effect of the esophageal membrane anatomical theory in esophageal cancer radical surgery. It elucidates the anatomical structure of the esophageal membrane and the lymphatic drainage characteristics of esophageal cancer, reveals the law of lymphatic metastasis in esophageal cancer, optimizes lymphatic dissection strategies, and improves the efficacy of esophageal cancer radical surgery.

CB1R blockade unmasks TRPV1-mediated contextual fear generalization in female, but not male rats.

Increasing evidence suggests that the neurobiological processes that govern learning and memory can be different in males and females, but many of the specific mechanisms underlying these sex differences have not been fully defined. Here we investigated potential sex differences in endocannabinoid (eCB) modulation of Pavlovian fear conditioning and extinction, examining multiple defensive behaviors, including shock responsivity, conditioned freezing, and conditioned darting. We found that while systemic administration of drugs acting on eCB receptors did not influence the occurrence of darting, females that were classified as Darters responded differently to the drug administration than those classified as Non-darters. Most notably, CB1R antagonist AM251 produced an increase in cue-elicited freezing and context generalization selectively in female Non-darters that persisted across extinction and extinction retrieval tests but was prevented by co-administration of TRPV1R antagonist Capsazepine. To identify a potential synaptic mechanism for these sex differences, we next employed biochemical and neuroanatomical tracing techniques to quantify anandamide (AEA), TRPV1R, and perisomatic CB1R expression, focusing on the ventral hippocampus (vHip) given its known role in mediating contextual fear generalization. These assays identified sex-specific effects of both fear conditioning-elicited AEA release and vHip-BLA circuit structure. Together, our data support a model in which sexual dimorphism in vHip-BLA circuitry promotes a female-specific dependence on CB1Rs for context processing that is sensitive to TRPV1-mediated disruption when CB1Rs are blocked.

Formation of new erosion-deposition patterns after farmland conversion: The major role of topography

The “Grain for Green” project has a profound impact on the allochthonous process of erosion sediment stripping and transportation, which in turn interferes with the distribution of erosion patterns. Therefore, understanding the changes in erosion patterns after farmland conversion and the factors controlling the new patterns of erosion distribution are essential for understanding the mechanism of slope erosion. Accordingly, this study investigated the formation of new erosion patterns and their control factors after farmland conversion by field sampling combined with nuclear tracing (137Cs) techniques, considering the “Grain for Green” project on the Loess Plateau as the study focus. We found that the implementation of the “Grain for Green” project can significantly reduce soil erosion intensity and create a new erosion-sediment source-sink pattern on the slope. The conversion of farmland to grassland can effectively store soil organic carbon as well as more environmentally sensitive active organic carbon, and the sorting effect on sediment particles is more obvious. Meanwhile, using stepwise regression, we found that the key limiting factor affecting the erosion intensity of farmland is the topography; the response of topographic factors to erosion is much higher than the physicochemical properties of the soil itself. By quantified the direct and interactive contributions to erosion intensity, we find that the direct contributions of silt and relief amplitude were 0.48 and 0.46 in farmland, while slope (0.16), Roughness (0.20) and Relief amplitude (0.33) in grassland, respectively. The interactive contributions were 0.06 and 0.30 in farmland and grassland. The conversion of farmland to grassland results in an increase in the factors that resist erosion and the factors interact more closely with each other to limit the occurrence of soil erosion. Our study provides scientific support for a deeper understanding of the slope erosion mechanism.

CAD-integrated stiffener sizing-topology design via force flow members (FFM)

Stiffener design plays a crucial role in the lightweight design of stiffened panels. We propose a CAD-integrated stiffener design approach for shells. The problem is partitioned into two steps: (1) generating clear force flow members (FFM) based on the direction of principal stress, and (2) introducing a nodal variable-based sizing-topology optimization for further lightweight design enhancement. Specifically, we generate dense principal stress trajectory families using the iterative tracing technique, and extract FFM through hierarchical clustering. Generating high-precision principal stress trajectories on free-form surfaces is a challenging task. Our method differs from previous approaches in that we employ tensor transformations to convert principal stress directions from the 3D physical space into the 2D parameter space. We then create NURBS curve-based FFM in the 2D parameter space. The NURBS-based free-form deformations (NFFD) technique is utilized to map FFM from the 2D parameter space to the 3D physical space, ensuring FFMs are precise and watertight constructions of geometries. We propose a nodal variable-based sizing-topology method for the lightweight design of FFM. The heights of FFM control points are designated as design variables. Steadily eliminating pseudo-heights is achieved by using the Sigmoid function to penalize the design variables. Moreover, we introduce an NFFD-based isogeometric analysis method for stiffened panels modeled by NFFD-based FFM to realize the integration of design and analysis. The effectiveness and robustness of the presented method are demonstrated through various benchmarks and examples with industrial backgrounds. The proposed optimization framework exhibits strong application potential in the lightweight design of stiffened panels.

Two parallel medial prefrontal cortex-amygdala pathways mediate memory deficits via glutamatergic projection in surgery mice

The neural circuit mechanisms underlying postoperative cognitive dysfunction (POCD) remain elusive. We hypothesized that projections from the medial prefrontal cortex (mPFC) to the amygdala are involved in POCD. A mouse model of POCD in which isoflurane (1.5%) combined with laparotomy was used. Virally assisted tracing techniques were used to label the relevant pathways. Fear conditioning, immunofluorescence, whole-cell patch-clamp recordings, and chemogenetic and optogenetic techniques were applied to investigate the role of mPFC-amygdala projections in POCD. We find that surgery impairs memory consolidation but not retrieval of consolidated memories. In POCD mice, the glutamatergic pathway from the prelimbic cortex to the basolateral amygdala (PL-BLA) shows reduced activity, whereas the glutamatergic pathway from the infralimbic cortex to the basomedial amygdala (IL-BMA) shows enhanced activity. Our study indicates that the hypoactivity in the PL-BLA pathway interrupts memory consolidation, whereas the hyperactivity in the IL-BMA promotes memory extinction, in POCD mice.

Novel Outline Tracing Techniques for Leaf Species Identification from Shrouded Leaves

Novel Outline Tracing Techniques for Leaf Species Identification from Shrouded Leaves

Cathodoluminescence as a tracing technique for quartz precipitation in low velocity shear experiments

Two simulated gouges (a pure quartz and a quartz-muscovite mixture) were experimentally deformed in a ring shear apparatus at a constant low velocity under hydrothermal conditions favourable for dissolution–precipitation processes. Microstructural analysis using scanning electron microscope cathodoluminescence imaging and cathodoluminescence spectroscopy combined with chemical analysis showed that quartz dissolution and precipitation occurred in both experiments. The starting materials and deformation conditions were chosen so that dissolution–precipitation microstructures could be unambiguously identified from their cathodoluminescence signal. Precipitated quartz was observed as blue luminescent fracture fills and overgrowths with increased Al content relative to the original quartz. In the pure quartz gouge, most of the shear deformation was localized on a boundary-parallel slip surface. Sealing of fractures in a pulverized zone directly adjacent to the slip surface may have helped keeping the deformation localized. In the quartz-muscovite mixture, some evidence was observed of shear-accommodating precipitation of quartz in strain shadows, but predominantly in fractures, elongating the original grains. Precipitation of quartz in fractures implies that the length scale of diffusive mass transfer in frictional-viscous flow is shorter than the length of the quartz domains. Additionally, fracturing might play a more important role than generally assumed. Our results show that cathodoluminescence, especially combined with chemical analysis, is a powerful tool in microstructural analyses of experimentally deformed quartz-bearing material and visualizing quartz precipitation.

On the Particle Motion in Paleo‐Magnetosphere During the Geomagnetic Polarity Reversal

AbstractDuring the Earth's magnetic reversal, the dipole component of the magnetic field weakens, and the non‐dipole component becomes dominant, resulting in a far more complex magnetospheric topology than that of a dipole. In this study, we used a particle tracing technique to investigate the motion of ions within an irregular magnetosphere during the Matuyama‐Brunhes magnetic polarity reversal. Compared to the scenario in which the geomagnetic field is dominated by a dipole component, earthward‐moving particles can be hardly “trapped” in the inner magnetosphere when the geomagnetic field experiences the polarity reversal, and particles can directly precipitate into the Earth's atmosphere on a global scale. It suggests that under an irregular magnetospheric configuration, the traditional trapped region of particles (e.g., radiation belt or ring current) no longer exists.

Pressure Characteristics and Vortex Observation in Chiral-Symmetric Space Orthogonal Bifurcation

In aerospace engine delivery systems, “one-in-two-out” bifurcation structures are commonly used for flow distribution to downstream pipelines. There are two common “one-in-two-out” bifurcation structures in aircraft engines: the planar orthogonal bifurcation and the spatial orthogonal bifurcation. By adjusting the flow supply upstream and the cross-sectional diameter downstream, the flow distribution in the two branches can be adjusted, i.e., the “splitting ratio” changes. In this paper, a dismantling and flexible experimental system is constructed to measure the pressure signals in each channel and use non-linear dynamic analysis methods to extract pressure characteristics. The particle image velocimetry (PIV) technique combined with the fine rope tracing technique is creatively used to observe the vortex structure in the cross section of the downstream branch. The study found that for spatial orthogonal bifurcation, the pressure signal characteristics in each channel are basically the same at larger splitting ratios, regardless of the chirality. As the splitting ratio decreases, the difference in pressure signal characteristics between the two branches gradually becomes evident and becomes related to the chirality. Moreover, unlike the planar orthogonal bifurcation structure, a complete large vortex structure has not been found in the downstream branch of the spatial orthogonal bifurcation structure, regardless of changes in the splitting ratio, and it is unrelated to the chirality.

A tradeoff between denitrification and nitrate leaching into the subsoil in nitrate-rich vegetable soils treated by reductive soil disinfestation

Intensive vegetable cultivation often leads to substantial accumulation of nitrate (NO3−-N) in the topsoil, thus posing serious threat to groundwater safety by NO3−-N leaching and food safety by excessive uptake of NO3−-N by vegetables. Reductive soil disinfestation (RSD) may remove over-accumulated NO3−-N in the topsoil due to its water-saturated, strongly reductive, and carbon-rich characteristics that favor the removal of NO3−-N via denitrification, immobilization, and leaching. However, how RSD affects the fates of NO3−-N of the topsoil in intensive vegetable lands remains largely unknown. Here, a soil column experiment using 15N tracing technique was conducted to quantify the fates of NO3−-N in the topsoil under RSD in six representative intensive vegetable soils in China. The results showed that an average of 99.7% of the added 15NO3−-N in the topsoil was removed by RSD in all intensive vegetable lands. Denitrification in the entire soil profile and leaching of NO3−-N into the subsoil were responsible for 21.8–78.3% and 14.9–68.4% of the removed 15NO3−-N, respectively, whereas microbial NO3−-N immobilization and dissimilatory nitrate reduction to ammonium in the topsoil played a negligible role in removing 15NO3−-N. A tradeoff was found between denitrification and leaching of NO3−-N into the subsoil among the six soils under RSD. The structural equation modeling demonstrated that the positive effects of RSD on topsoil pH, dissolved organic carbon, and bacterial abundance decreased the leaching of NO3−-N into the subsoil by enhancing denitrification. Overall, the results provided the first direct evidence for complete removal of NO3−-N in the topsoil by RSD. Such an evidence has implications for controlling NO3−-N accumulation through implementing RSD in intensive vegetable soils.

Bifocal Dual Reflectarray with Curved Main Surface

This paper presents a novel approach to synthesizing curved reflectarrays using Geometrical Optics (GO). It introduces the concepts of virtual normal and path length shift, which enable a vector-based formulation of the problem that can be solved using ray tracing techniques. The formulation is applied for the design of two different versions of a Dual Bifocal Reflectarray with a parabolic main surface and a flat subreflectarray. The first version aims to enhance the performance of the multibeam antenna by providing a focal ring located at the feed cluster plane. The second version focuses on improving the scanning characteristics of the antenna in the horizontal plane by incorporating two foci. The synthesis procedure yields samples of the path length shift or its derivatives. To reconstruct the phase distribution, an interpolation scheme is employed and described in this paper. Numerical results are presented for both the focal-ring and two-foci configurations, demonstrating the feasibility of this solution for multibeam or scanning satellite antennas operating in the Ka.

Radiative view factor correlations in particulate media from ray tracing simulations and data-driven modeling

Thermal radiation has been extensively modeled in static particulate media with effective radiative properties or with statistical ray tracing techniques. However, these techniques are not directly compatible to evaluate radiative fluxes on discrete particles, which is more suitable for particle flow systems. This study focuses on such a discrete approach to compute radiative fluxes by developing view factors correlations for particle-particle and particle-wall. Training data is generated from physics-based Monte Carlo ray tracing simulations on a monodisperse, packed bed with solid volume fractions ranging from 0.016 to 0.45. This data was used to develop reduced-order correlations to determine particle-particle and particle-wall radiative view factors as a function of particle-particle and particle-wall separation distance, viewing angle, and the number of shading particles. Uniquely, we determine best-fit functions that are physically interpretable to account for shading effects by particles. A sigmoid function with a non-linear dependence on viewing angle governs the extent of shading by an intermediate particle. A correction factor with the particle-wall normal separation distance as the feature variable is introduced to account for shading effects between a particle and a planar wall surface. View factor correlations result in reliable and reasonably accurate predictions. For a solid volume fraction of 0.45, the root mean squared errors of particle-particle and particle-wall view factors are 2.7e-4 and 0.021 with corresponding training data in the ranges of 0–0.08 and 0–0.5 respectively. To scale these correlations for large number of particles, restricting shading detection up to 5 nearest neighbors is demonstrated to be an effective strategy to balance prediction accuracy with computational efficiency. With thousands of particles, the computational cost of proposed view factor correlations with thresholding of 5 shading particles is about 100 times faster than serial Monte Carlo ray tracing simulations for a solid volume fraction of 0.45.