Front Region Research Articles

VANTAGENS DOS IMPLANTES UNITÁRIOS COM CARGA IMEDIATA EM REGIÃO ANTERIOR DE MAXILA: REVISÃO DE LITERATURA

Among the various teeth that can be lost, the front ones are the most relevant in terms of aesthetics, since they represent an individual’s calling card. In this scenario, implantology is one of the main forms of oral rehabilitation in dentistry. Dental implants can be installed with immediate or delayed loading. Immediate loading implants arose from the need for faster results and in situations where aesthetics are the main objective, such as the front region of maxilla, representing a huge technological advance in implantology. The present study aimed to conduct a literature review on the advantages of single immediate loading implants in the front of maxilla. Through a search in the online databases Google Scholar, Pubmed and Scielo, 25 scientific articles were selected to compose the review, divided into the following topics: mediate loading vs. immediate loading; requirements for the application of immediate loading in single implants; immediate loading in the front of maxilla and its advantages; and the success rates. After explaining and discussing the data, it was concluded that single immediate loading implants in the front of maxilla is considered effective, especially due to advantages such as immediate aesthetic restoration and reduced treatment time, benefits considered extremely important by most patients. However, it is important to emphasize that the professional must evaluate each case individually and decide whether the patient is suitable for the technique.

Research on the initiation and wavefront evolution of diverging cylindrical detonations of acetylene and oxygen mixtures

The present study focuses on fundamental research about the transition from a planar detonation to a cylindrical detonation and the propagation of the diverging cylindrical detonation. We aim to figure out the mechanism of the transition and propagation of the diverging cylindrical detonation by analyzing the cellular pattern and critical initial pressure. The findings highlight that the successful detonation in a cylindrical chamber via transition through a straight channel is predominantly influenced by diffraction at the corners and the successive continuous reflections between the front and rear walls. Depending on the initial pressure, the initiation modes exhibit characteristics of subcritical, critical, and supercritical three-stage processes. Sustained propagation of cylindrical detonations necessitates increasing the number of cells to match the growth rate in the front region. Experimental investigations reveal two distinct modes of cell number increase: mild and violent. In the case of the former, cell number increase predominantly occurs on a scale of two to three times the characteristic cell size of the Chapman-Jouguet detonation. In contrast, a decaying Mach stem undergoes twisting and evolves into local kinks, leading to the development of new triple-wave points. The latter mode typically occurs near the limit, where cell increase primarily arises from randomly occurring local explosions, and operates on a scale of ten times the characteristic cell size or the chamber diameter. In addition, a numerical study of two-dimensional fundamental problems abstracted from the experiment is conducted to help interpret experimental results and reveal more about the physics of the problem.

A Short-term Vehicle Speed Prediction Approach considering Dynamic Traffic Scene

Vehicle speed serves as a crucial indicator in traffic flow efficiency and safety evaluation. Previous researches typically utilize the time-series data of target vehicle speed or the relative speed and distance between the target and leading vehicles as speed prediction model input, which are suitable for stable and single-vehicle scenes. However, the surrounding traffic scenes dynamically changes during the vehicle’s driving process, the driver needs to allocate attention to the key scene vehicles in the surrounding traffic scenes and adjust the current speed based on these vehicles’ behavior. Therefore, this paper proposes a short-time vehicle speed prediction model considering the dynamic traffic scenes. A dynamic grid method is adopted to divide the target vehicle’s surrounding areas into left front, front, and right front regions. And key scene vehicles are identified based on each region’s state. Then the relative distance, speed, and acceleration data between the target vehicle and key scene vehicles are selected as model inputs. Vehicle trajectory data from the South-North No. 1 Expressway in Hefei and Ranger optimized Temporal Convolutional Network (TCN) are utilized to train the speed prediction model. Experiment results indicated that under 1s, 2s, and 3s prediction lengths, the model’s average Root Mean Square Error (RMSE) and Mean Absolute Error (MAE) were 0.430 and 0.271 respectively. Compared to the speed prediction model considering the static traffic scenes, the average RMSE and MAE for the three prediction lengths have been reduced by 49.15% and 56.02% respectively.

Managing impressions: performance and identity in police leadership in the pandemic

ABSTRACT Critical leadership scholars have long recognised leadership as performative and reveal the symbolic, presentational and ritual aspects of leadership practice as meaning-making. This perspective, however, is neglected in mainstream understanding of police leadership. Drawing on Goffman’s dramaturgical framework and a qualitative study of policing leaders in the UK, this paper explores performativity and police leadership in the context of the COVID-19 pandemic. Removed from occupational symbols of the police station and performing leadership work exclusively in the home environment, the findings show that police leaders used the uniform as part of a strategy of impression management to construct front and back stage regions in the domestic sphere. In frontstage settings, the uniform was used to represent occupational authority and reinforce a sense of shared, professional identity and purpose, despite the physical separation between leaders and their staff. Alongside this, police leaders constructed and maintained backstage spaces for preparatory and reparative work, even within the home-working setting. The findings challenge traditional conceptualisations of the backstage as physical, boundaried space of the police station and instead reveal backstage space as fluid, dynamic and imagined. As police constabularies consider the impact of remote-working practices on the police workplace, the preservation of backstage spaces for police leaders during the COVID-19 pandemic reveals the value and necessity this backstage work in police leadership.

When the neighbors are noisy: effect of social challenge in collateral pens of stressed animals.

Regrouping practices are frequent in pig production, altering hierarchy and triggering aggressive behaviors. The present study aimed to investigate the physiological responses of piglets to an experimental model designed to induce stress through systematic social mixing in two trials. In Trial A, a total of 144 crossbred piglets (25 days postweaning) housed in one room within 36 pens (four piglets/pen) were used and randomly assigned to either a control group (piglets maintained in their pen, Ctrl-A) or a social challenge group (piglets mixed, SC-A). In Trial B, the same number of animals (33 days postweaning) and crossbreed line was used, and each piglet was assigned either to a control group (Ctrl-B) or a social challenge group (SC-B) in two independent rooms (rooms Ctrl and SC, 12 pens/ room, six piglets/pen). The social challenge consisted of daily moves of three out of four pen mates and five out of six pen mates, for Trials A and B, respectively. In the Ctrl groups, all piglets stayed in their original pen. Before the 1st mixing day and at the end of the 3rd mixing day, saliva (cortisol concentration) and blood (cortisol concentration changes, hemogram, and immunologic activation) samples were collected from two random piglets per pen. Skin lesion scores of all piglets were also recorded on the front, middle, and rear body regions. In Trial A, the total skin lesions score was higher in the SC-A group compared to the Ctrl-A group after the social challenge (0.53 vs. 0.17; p < 0.05), but an unexpected increase between sampling days in the Ctrl-A piglets (0.06 vs. 0.17; p < 0.05) was also recorded, suggesting that Ctrl-A pigs showed similar aggressivity levels to the SC-A group. Hematological parameters hemoglobin, red blood cell counts, and leukocyte counts present similar changes in both treatment groups after the social challenge. Contrarily, in Trial B, the lesion score only increased in the piglets in room SC (0.08 vs. 0.34; p < 0.05). Results suggest that stable groups may show aggressive behaviors if they are in the same room with socially challenged pigs. Thus, the physical separation of treatment groups in social stress studies is recommended.

Macrophages play a crucial role in vascular smooth muscle cell coverage.

The microvascular system consists of two cell types: endothelial and mural (pericytes and vascular smooth muscle cells; VSMCs) cells. Communication between endothelial and mural cells plays a pivotal role in the maintenance of vascular homeostasis; however, in vivo molecular and cellular mechanisms underlying mural cell development remain unclear. In this study, we found that macrophages played a crucial role in TGFβ-dependent pericyte-to-VSMC differentiation during retinal vasculature development. In mice with constitutively active Foxo1 overexpression, substantial accumulation of TGFβ1-producing macrophages and pericytes around the angiogenic front region was observed. Additionally, the TGFβ-SMAD pathway was activated in pericytes adjacent to macrophages, resulting in excess ectopic α-smooth muscle actin-positive VSMCs. Furthermore, we identified endothelial SEMA3C as an attractant for macrophages. In vivo neutralization of SEMA3C rescued macrophage accumulation and ectopic VSMC phenotypes in the mice, as well as drug-induced macrophage depletion. Therefore, macrophages play an important physiological role in VSMC development via the FOXO1-SEMA3C pathway.

Effects of exposure sequence and GGBS cement replacement on performance of concrete subjected to carbonation and chloride ingress

In a variety of applications, such as in tidal zones, abutments of bridges and concrete tunnel linings, reinforced concrete is exposed to both carbonation and chloride ingress. The exposure can be either simultaneous or sequential. However, durability design rarely considers synergistic effects due to carbonation and chloride ingress, even though this may have detrimental consequences for performance. Comparative implications of exposure sequence across different concrete compositions are also unknown. In this study, an experimental investigation on the effects of the sequence of carbonation and chloride ingress was conducted, using two concretes which differ by 50% cement replacement with ground granulated blast furnace slag (GGBS). Specimens were exposed to a combination of 10% CO2 accelerated carbonation and immersion in 3% sodium chloride solution, in either sequence, and compared with companion samples subjected to only one of these aggressive environments. The extent of carbonation was measured using phenolphthalein indicator solution, while silver nitrate and Rapid Chloride Testing provided indicators of the chloride ingress. For both concrete mixes, specimens with prior chloride ingress exhibited a decreased rate of carbonation when compared to specimens with no prior exposure. Conversely, specimens with prior carbonation displayed an increased rate of chloride ingress compared to non-carbonated counterparts and a step in the acid soluble chloride content in the region of the carbonation front. The concrete composition appeared to play a role since a greater increase in chloride diffusion coefficient due to prior carbonation was observed in the mix with 50% GGBS replacement than the mix without. These findings suggest that in concrete structures exposed to air and saline environments, the effects of sequential exposure should be characterised.

Organic carbon cycling in the sediments of Prydz Bay, Eastern Antarctica: Implications for a high carbon sequestration potential

Understanding the dynamics of sedimentary organic carbon (SOC) in the productive continental marginal sea surrounding Antarctica is crucial for elucidating the effect of this sea on the global carbon cycle. We analyzed 31 surface sediment samples and eight sediment cores collected from Prydz Bay (PB) and the adjacent basin area. The element and stable isotope compositions, grain size compositions, and biogenic silica and lithogenic minerals of these samples were used to evaluate the spatial variations in the sources, transport mechanisms, and preservation patterns of SOC, with a particular focus on the efficiency of the biological carbon pump (BCP). Our findings reveal that the SOC originated from mixed marine/terrestrial sources. The δ13C values were higher in the Prydz Bay Gyre (PBG) region than in the open sea area. Biogenic matter-rich debris, associated with fine-grained particles (silt and clay), was concentrated in the PBG, while abiotic ice-rafted debris and coarse-grained particles were preferentially deposited in the bank and ice shelf front regions. Lithogenic matter predominated in the basin sediments. The annual accumulation rate of SOC in PB ranged from 1.6 to 6.2 g·m−2·yr−1 (mean 4.2 ± 1.9 g·m−2·yr−1), and the rates were higher in the PBG than in the ice shelf front region. Estimates based on our tentative box model suggest that the efficiency of the BCP, which refers to the proportion of surface-produced organic carbon successfully transferred to deep waters, is approximately 5.7 % in PB, surpassing the global average (∼0.8 %) and the efficiencies reported for other polar environments. Furthermore, our calculations indicate that the SOC preservation efficiency (the ratio of preserved to initially deposited organic carbon in sediments) in PB is approximately 79 % ± 20 %, underscoring the significant carbon sequestration potential within PB. The results of this study have important implications for the effects of sediment dynamics on the carbon cycle in the sea surrounding Antarctica.

Anterior Cervical Bronchogenic Cyst Mimicking a Thyroglossal Duct Cyst: A Case Report.

A bronchogenic cyst (BC) is a rare congenital cystic lesion, especially when located in the suprahyoid region of the anterior cervical front. We report a case of a male child who was misdiagnosed with a thyroglossal duct cyst due to the clinical presentation of a mass located near the anterior midline of the neck, in the region above the hyoid bone, which moved up and down with swallowing, characteristics consistent with a thyroglossal duct cyst. We excised the lesion under general anesthesia. Histopathological analysis revealed cartilage tissue, pseudostratified columnar epithelium of the cyst wall with cilia and mucous glands, finally diagnosing it as BC. BC should be considered in the differential diagnosis of neck masses.

Effect of environmental drivers on the spatiotemporal distribution of mackerel at age in the Nordic Seas during 2010−20

Abstract A joint spatio–temporal distribution model of mackerel (ages 3–10) was developed to investigate the age-based responses of mackerel to three environmental drivers: sea surface temperature (SST), mixed layer depth, and chlorophyll-a concentration during the summer months 2010–20 in the Nordic Seas. The study showed that SST was the most important variable amongst the ones tested and had the strongest impact on the distribution of the younger age classes (3–5), which had a narrower range of favourable SST and a stronger aversion to cold temperatures than older individuals. Consequently, the impact of SST differed regionally; in the polar front regions, SST explained up to 61% of the variability in the observed density of young individuals, where Arctic water masses likely acted as a barrier to these young individuals. That said, part of it could be confounded with the limited migration capability of young mackerels, which could not reach the furthest frontal regions. In warmer southern waters, the same environmental variables had less explanatory power for mackerel of all ages. Individuals in the south were likely not constrained by temperature and perhaps more influenced by other variables, such as food availability or ocean current (throughout their migration path), for which appropriate data are lacking. Moreover, the model showed that older mackerel were distributed more to the north and west, and their migration pattern changed when the 2013 year-class no longer migrated to the west compared to previous year-classes. Additionally, all-year classes started migrating more eastward from summer 2018.

Circulation and Hydrography in the Northwestern Barents Sea: Insights From Recent Observations and Historical Data (1950–2022)

AbstractThe Barents Sea is one of the main pathways for warm and saline Atlantic Water (AW) entering the Arctic Ocean. It is an important region where water mass transformation and dense‐water production contribute to the Atlantic meridional overturning circulation. Here, we present data from three cruises and nine glider missions conducted between 2019 and 2022 in the northwestern Barents Sea, and compare them with historical data collected between 1950 and 2009. We present circulation pathways, hydrography and volume transports of Atlantic‐ and Arctic‐origin waters. Our observations show that 0.9 ± 0.1 Sv (1 Sv = 106 m3 s−1) of Atlantic‐origin water reaches the Polar Front (PF) region before splitting into several branches and eventually subducting beneath Polar Water (PW). The amount of Atlantic‐origin water stored in the Olga Basin north of the PF is controlled by the density difference between AW and PW, and reached a maximum in the 90s when PW was particularly fresh. In the recent period from 2019 to 2022, the inflow of AW into the Barents Sea freshened by up to 0.1 g kg−1 compared to previous decades. This led to a reduction in the production of dense water, an increased temperature gradient across the PF, and a reduced poleward transport of warm water.

Computational study of momentum interactions between fluid and a static particle under the impact of anisotropic Stefan flow

The microscale gas–particle interaction is the determining process for the macroscopic flow behaviors of gas–particle systems. Anisotropic Stefan flow is often manifested at the surface of the biomass particle when thermally decomposed. However, the influence of the anisotropic Stefan flow on the gas–particle interactions is not well understood. To this end, particle-resolved direct numerical simulations were carried out in this research to explore the momentum interactions between the gas flow and a static particle emitting mass flux at its surface. A signed distance function based immersed boundary method is first extended to account for the Stefan flow at the gas–particle interface and successfully validated by comparing with literature results in the case of no Stefan flow or uniform Stefan flow. It is found that the presence of the outward uniform Stefan flow leads to an expanded wake formation and the intensity of the vortex (Re ≥ 40) is enhanced as result of the Stefan flow. Subject to the impact of anisotropic Stefan flow parallel to the main flow, the low-speed region in the front and rear of the particle is reduced when the Stefan flow goes inwards, resulting in the increase in the drag coefficient. As the Stefan flow is outward, the low-speed region in the front of the particle is pushed forward by the emitting gas and the velocity magnitude in the wake region is increased, which behaves like an enlargement of the gas cushion and leads to a significant reduction of the drag coefficient comparing with a uniform Stefan flow. In contrast, the impact of anisotropic Stefan flow with the direction perpendicular to the main flow on the fluid–particle drag interaction is less significant due to the fact that the flow structure in the front and rear regions is not significantly disturbed.

Temporary Hydrostatic Splint Therapy and Its Effects on Occlusal Forces.

Background and objectives: This study analyzed and compared the distribution patterns of occlusal forces using T-Scan III before and after the hydrostatic temporary oral splint (Aqualizer Ultra) therapy in healthy subjects and subjects with temporomandibular disorders (TMDs). Materials and Methods: Fifty-one subjects were divided into groups based on anamnesis and responses to the Fonseca questionnaire. The first group, non-TMDs group (n = 19), and the second group, TMDs group (n = 32), had mild-to-severe TMDs, as identified by the Fonseca questionnaire. The non-TMDs group had an average age of 25.4 years (SD = 4.8, range 20-38) with 15 females (78.95%) and 4 males (21.05%). The TMDs group had an average age of 27.4 years (SD = 7.0, range 22-53) with 25 females (78.125%) and 7 males (21.875%). T-Scan III device was used for occlusal analysis before and after hydrostatic splint usage. Results: Significant differences were observed in the TMDs group for anterior and posterior right percentages of forces before and after hydrostatic splint usage. The analysis of force distribution per sector before and after hydrostatic splint therapy showed no significant differences in the non-TMDs group. Analysis of force distributions in the entire study population before and after hydrostatic splint therapy showed significant differences in the anterior and posterior right regions. Occlusal force increased by 32-56% in the front region and decreased in the posterior area after hydrostatic splint usage. Conclusions: Hydrostatic splint therapy is recommended as a part of full-mouth rehabilitation treatment for all patients regardless of the severity of TMDs.

Double-diode model carrier lifetime-based internal recombination parameter analysis and efficiency prediction of crystalline Si solar cells

With the continuous and significant advancements in the performance of crystalline silicon (c-Si) solar cells, an effective method for a detailed analysis of the efficiency loss factors is increasingly important. Specifically, a detailed analysis of recombination parameter (J0) is crucial for devising strategies to approach the theoretical efficiency limit. In this study, we propose an analysis method that utilizes minority carrier lifetime based on the double-diode model and predicts the performance efficiency of c-Si solar cells. The analysis, conducted through the p-PERC structure, examines the contributions to J0 from different recombination areas. The advantages of this method include: (i) its relative simplicity and reliance on non-destructive analysis techniques; (ii) its capability to extract internal recombination parameters, such as J0,total emitter, J0,rear, and J02, from a fully assembled solar cell with metal contacts. Furthermore, this method serves as a diagnostic tool to identify the sequence in which parameters should be adjusted to enhance solar cell efficiency effectively and to pinpoint areas within the solar cell that significantly limit performance efficiency. Using this method, the diagnosis of the p-PERC cell revealed that the main cause of performance limitation was the emitter in the front region. The carrier lifetime analysis showed that for overcoming cell performance limitations, it is more effective to design process improvements in the following order: i) front emitter region (J0,em), ii) space charge region (J02), iii) rear surface region (J0r).

Riding transit to parks in Utah: Motivations, constraints, negotiations, and policy recommendations

In this paper, we studied the motivations, constraints, negotiations, and policy changes for riding transit to parks in Utah’s Wasatch Front region, exploring how these factors vary between disadvantaged and non-disadvantaged individuals. This is one of the first studies to explore transit-to-parks experiences in large urban regions. We conducted interviews with 25 diverse transit riders. Motivations for riding transit to parks included environmental concerns and the convenience of avoiding parking and traffic. Constraints involved excessive travel time due to limited service, transit frequency and reliability issues, and last-mile connection issues. The main negotiation strategy was to plan trips to limit travel time. People in low-income neighborhoods had limited transit-to-parks services, and available services were adequate for fit and non-disabled people. Policy changes that would help participants address constraints included new or modified routes, improved last-mile connections, information and marketing campaigns, and better service for low-income communities and people with disabilities.

Air–sea heat fluxes variations in the Southern Atlantic Ocean: Present‐day and future climate scenarios

AbstractThis study investigates the variations in air–sea heat fluxes and temperatures in two ocean front regions, the Southwestern Atlantic Ocean (SWA) and the Drake Passage, widely recognized as hotspot areas with significant influences on South America weather and climate. We analyse means and trends of latent and sensible heat fluxes (LHF and SHF) and their associated air–sea temperatures (SAT and SST), based on monthly ERA5 (1985–2014) and eight CMIP6 models, for historical and long‐term simulations (2015–2099). The ERA5 trend for all parameters was positive over SWA, contrasting with the negative values observed in the Drake Passage, indicating surface warming and cooling, respectively. In the SWA, the ERA5 and CMIP6 multi‐model ensemble (MME) align in SST and SAT values, with a historical trend of 0.1°C·decade−1 and a significantly increasing trend in warming estimated by 0.4°C·decade−1 up to 2099. The ERA5 LHF and SHF trends were 4 and 0.6 W·m−2·decade−1, respectively. The MME shows historical (SSP5‐8.5) trends of 0.2 (1.3) W·m−2·decade−1 for LHF and −0.2 (−0.1) W·m−2·decade−1 for SHF. In the Drake Passage, the models accurately reproduced the air–sea mean temperatures; however, they failed to simulate negative trends observed in SAT and SST. Under the high emissions scenario, all CMIP6 models predict an increasing warming trends of 0.1–0.4°C·decade−1 and ocean heat gain of −0.2 to −1.2 (−1 to −2) W·m−2·decade−1 for LHF (SHF). For both regions, spatial analyses of SST and SAT highlight the coupling between the ocean and the atmosphere, alongside changes in air–sea heat fluxes. Our findings reveal inhomogeneous patterns of SST warming trends by the end of the 21st century, which are approximately 2–4 times greater than historical trends. The results suggest the persistence and enhancement of these regions as hotspots with significant potential to influence oceanic and atmospheric dynamics.

The Influence of River Plume Discharge and Winds on Sediment Transport into a Coastal Mangrove Environment

We investigate how the physical forcing factors of river discharge and winds affect sediment delivery to, and retention within, mangrove-lined coastal regions. We use an idealized numerical model, broadly similar to the Firth of Thames deltaic system in New Zealand, to isolate and explore the underlying processes without some of the complexities of the real system. Total sediment transport and the relative contributions of riverine and bed-sourced sediment into the forest are assessed using a transect along the edge of the forest region. The model results demonstrate that both river discharge and winds alter the distribution of sediment transport, and that the spatial patterns relate to different regions of the river plume. At the river mouth (the near-field region), irrespective of the discharge employed, sediment fluxes are directed into the mangrove forest, indicating an accretionary environment consistent with satellite observations. Here, contributions from the riverine and bed-sourced sediments are similar. For small to medium discharge scenarios (up to ∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document} 280 m3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{3}$$\\end{document} s-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{-1}$$\\end{document}, flow speeds ∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document} 0.6 m s-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{-1}$$\\end{document}), mass loads increase with river discharge. However, in the case of large discharge events, the high momentum in the near-field region allows the river plume to effectively transport sediment through the full width of forested region and out of the forest front. In the mid- and far-field regions of the plume, tidal influences also play a stronger role. Suspended sediment is primarily composed of bed-sourced material and transported out of the forest. Weaker winds are found to affect the far- and mid-field regions of the river plume. Stronger winds are able to reshape the entire plume structure, also including the near-field, such that sediment deposition is enhanced when winds are directed towards the forest.

Heat front propagation in shale oil reservoirs during air injection: Experimental and numerical studies

Air injection technique for developing shale oil has gained significant attention. However, the ability of the heat front to consistently propagate within the shale during air injection remains uncertain. To address this, we investigated the heat front propagation within oil–detritus mixtures, shale cores, and fractured shale cores using a self-designed combustion tube (CT) and experimental schemes. By integrating the results obtained from high-pressure differential scanning calorimetry and CT, we developed a comprehensive reaction kinetics model to accurately analyze the main factors influencing the heat front propagation within fractured shale. The findings revealed that in the absence of additional fractures, the heat front failed to propagate within the tight shale. The flow of gases and liquids towards the shale core was impeded, resulting in the formation of a high-pressure zone at the front region of the shale. This pressure buildup significantly hindered air injection, leading to inadequate oxygen supply and the extinguishment of the heat front. However, the study demonstrated the stable propagation of the heat front within the oil–detritus mixtures, indicating the good combustion activity of the shale oil. Furthermore, the heat front successfully propagated within the fractured shale, generating a substantial amount of heat that facilitated the creation of fractures and enhanced gas injection and shale oil flow. It was important to note that after the heat front passed through the shale, the combustion intensity decreased. The simulation results indicated that injecting air into the main fracturing layers of the shale oil reservoir enabled the establishment of a stable heat front. Increasing the reservoir temperature (from 63 to 143 °C) and oxygen concentration in the injected gas (from 11% to 21%) promoted notable heat front propagation and increased the average temperature of the heat front. It was concluded that temperature and oxygen concentration had the most important influence on the heat front propagation, followed by pressure and oil saturation.

Evaluation of thermal storage system during freezing and loading nano-powders

In pursuit of advancing the efficiency of cold energy storage, a uniquely designed curved container has been employed, filled with a water-nanoparticle mixtureQ. The container is equipped with fins, strategically leveraging the enhanced conduction facilitated by the presence of nanoparticles. The simulation of the intricate unsteady phenomena in this study has been conducted using the finite element technique, providing a robust analytical framework. The incorporation of an adaptive grid ensures a refined resolution, particularly in the vicinity of the ice front region. The nanoparticle fraction (ϕ) emerges as a pivotal factor directly influencing the rate of solidifying. The dispersion of nano-powders leads to a noteworthy reduction in completion time, demonstrating a substantial 33.21% improvement. The diameter of the nano-powders (dp) introduces diverse effects on the solidification process, primarily due to its significant influence on the conductivity of the nanomaterial. An in-depth exploration of the impact of dp reveals compelling insights. As the dp increases from its smallest size to 40 nm, there is a commendable 15.12% reduction in the required freezing time. However, a subsequent increment in dp beyond this threshold results in a notable 36.56% increase in the freezing time. The findings presented here not only contribute to the fundamental understanding of freezing processes but also hold practical implications for the design and optimization of cold storage systems.

Drivers of organic carbon distribution and accumulation in the northern Barents Sea

Sedimentary properties and accumulation rates on the continental shelf and in the deep sea reflect temporal oceanographic, biological and chemical processes occurring in the water column and the sediment surface. We used the radionuclides 210Pb, 226Ra, and 137Cs activities to estimate sedimentation rates during the last century at nine stations in the northern Barents Sea region. Elemental (C, N) and stable isotopic composition (δ13C, δ15N) were also analysed from the nine stations sampled in August 2018, and, for five other stations sampled in August and December 2019, and in March and May 2021. Sediment accumulation rates varied between 130 and 1 410 g m−2 y−1. The < 63 μm normalized total organic carbon (TOC63) and the total nitrogen from the sediment surface varied between 0.90–2.56 % and 0.13–0.33 %, respectively. Ice-free shelf stations had higher TOC63 and possibly fresher organic matter (high δ13C, low δ15N) than ice-covered more northern stations. The opposite trend was observed for total inorganic carbon. We found that these trends in biogeochemical parameters were spatially structured by the winter sea ice concentration and biological production differences, and exhibited a south-north separation of the Polar Front region. The low and stable organic carbon accumulation rate (1.7–13.4 g Corg m-2 y−1; ARtoc) is a function of slow sedimentation rates, and high degradation and residence time in the water column and at the sediment–water interface. Overall, the ARtoc has been stable for the past 100 years, with a slight increase from the early 1970s to the present at the shelf and slope stations. Our results highlight that spatial scales of variability of the studied sedimentary parameters are linked to spatial patterns of important environmental variables (e.g., chlorophyll-a, sea ice concentration) in the region. In contrast, no seasonal differences were observed in the sediment parameters of revisited stations, and the dated sediment geochemical profiles did not exhibit substantial longer-term variation. This means that climate-induced changes in variables that modify the sedimentary geochemistry of the environment may affect benthic community activity and structure before leaving a record in ARtoc.