Systemic Circulation Research Articles

Demonstration of Membrane Transport of Histidine using Goat Intestinal Inverted Sacs: An Experiential Pedagogical Tool for Undergraduates.

Histidine is an essential amino acid that is also a precursor for metabolites implicated in the immune system, pulmonary ventilation, and vascular circulation. Absorption of dietary histidine relies largely on the sodium-coupled neutral amino acid transport by the Broad neutral amino acid transporter (B0AT) present on the apical membrane of the enterocyte. Here, we demonstrate the absorption of histidine by the intestinal villus enterocytes from the lumen using goat jejunal inverted sacs. The jejunal sacs exposed to varying concentrations of sodium and histidine were assayed to determine the concentration of histidine inside the sacs as a function of time. The results show active histidine absorption. Increasing the concentration of salt resulted in higher absorption of histidine, suggesting a symport of sodium and histidine absorption in goat intestinal inverted sacs. This protocol may be applied to visualize the intestinal mobility of amino acids or other metabolites with appropriate modifications. We propose this experiment as an experiential pedagogical tool that can help undergraduate students comprehend the concept of membrane transport.

Hemodynamic Disorders in Alcohol Withdrawal Syndrome

INTRODUCTION: The introduction of the study is determined by a high prevalence of alcoholism and a high incidence of complications from the cardiovascular system. AIM: To study the features of hemodynamics in patients with uncomplicated alcohol withdrawal syndrome (AWS) and in those with alcohol withdrawal delirium (delirium tremens). MATERIALS AND METHODS: The study enrolled 116 men, 58 of them with uncomplicated AWS, 78 with AWS and delirium. Basic hemodynamic parameters were studied: heart rate (HR), blood pressure (BP), and integral parameters — cardiac index (CI), total peripheral resistance (TPR), shock index (SI). Comparisons between the groups and correlation analysis were conducted to find relationships between hemodynamic parameters and clinical data. RESULTS: In patients with alcoholic delirium, hemodynamic parameters were statistically significantly higher than in patients with uncomplicated AWS: HR (р = 0.003), systolic BP (р = 0.02) and diastolic BP (р = 0.04), while no statistically significant differences in the integral parameters (CI, TPR, SI) were found between the groups. In patients of both groups, CI linearly decreased with age (p 0.0001). The same linearly CI decreased with increase in the duration of alcoholism (p = 0.02). With an increase in the amount of consumed alcohol during the binge period, a linear growth of CI was observed in withdrawal state (p = 0.001). The value of TPR increased with age (p = 0.005). Only in patients with delirium tremens, there was an inverse relationship between SI and partial tension of carbon dioxide in venous blood (r = -0.4; p = 0.014). Besides, only in patients with delirium tremens, by the 7th day of withdrawal, a direct relationship was established between the cardiac index and blood potassium level (r = 0.36; p = 0.03). CONCLUSIONS: There was no significant difference between hemodynamic parameters in uncomplicated AWS and in delirium tremens. CI in patients with uncomplicated AWS and in those with DT decreased with age and with increase in the alcohol load. The vessel tone was inversely proportional to CI throughout the entire period of observation. With the development of delirium, a correlation was noted between a decrease in the level of energy metabolism and the probability for decompensation of systemic circulation. At the stage of reduction of delirium tremens, a correlation was noted between CI and the blood potassium level that reflected the exhaustion of the cardiovascular system and reduction of its compensatory capacities.

Evaluation of Gremlin-1 as a therapeutic target in metabolic dysfunction-associated steatohepatitis

Gremlin-1 has been implicated in liver fibrosis in metabolic dysfunction-associated steatohepatitis (MASH) via inhibition of bone morphogenetic protein (BMP) signalling and has thereby been identified as a potential therapeutic target. Using rat in vivo and human in vitro and ex vivo model systems of MASH fibrosis, we show that neutralisation of Gremlin-1 activity with monoclonal therapeutic antibodies does not reduce liver inflammation or liver fibrosis. Still, Gremlin-1 was upregulated in human and rat MASH fibrosis, but expression was restricted to a small subpopulation of COL3A1/THY1+ myofibroblasts. Lentiviral overexpression of Gremlin-1 in LX-2 cells and primary hepatic stellate cells led to changes in BMP-related gene expression, which did not translate to increased fibrogenesis. Furthermore, we show that Gremlin-1 binds to heparin with high affinity, which prevents Gremlin-1 from entering systemic circulation, prohibiting Gremlin-1-mediated organ crosstalk. Overall, our findings suggest a redundant role for Gremlin-1 in the pathogenesis of liver fibrosis, which is unamenable to therapeutic targeting.

Evaluation of Gremlin-1 as a therapeutic target in metabolic dysfunction-associated steatohepatitis.

Gremlin-1 has been implicated in liver fibrosis in metabolic dysfunction-associated steatohepatitis (MASH) via inhibition of bone morphogenetic protein (BMP) signalling and has thereby been identified as a potential therapeutic target. Using rat in vivo and human in vitro and ex vivo model systems of MASH fibrosis, we show that neutralisation of Gremlin-1 activity with monoclonal therapeutic antibodies does not reduce liver inflammation or liver fibrosis. Still, Gremlin-1 was upregulated in human and rat MASH fibrosis, but expression was restricted to a small subpopulation of COL3A1/THY1+ myofibroblasts. Lentiviral overexpression of Gremlin-1 in LX-2 cells and primary hepatic stellate cells led to changes in BMP-related gene expression, which did not translate to increased fibrogenesis. Furthermore, we show that Gremlin-1 binds to heparin with high affinity, which prevents Gremlin-1 from entering systemic circulation, prohibiting Gremlin-1-mediated organ crosstalk. Overall, our findings suggest a redundant role for Gremlin-1 in the pathogenesis of liver fibrosis, which is unamenable to therapeutic targeting.

PROGRESSIVE SYSTEMIC INFLAMMATION PRECEDES DECOMPENSATION IN COMPENSATED CIRRHOSIS

Background & AimsSystemic inflammation is a driver of decompensation in cirrhosis with unclear relevance in the compensated stage. We evaluated inflammation and bacterial translocation markers in compensated cirrhosis and their dynamics in relation to the first decompensation. MethodsThis study is nested within the PREDESCI trial, which investigated non-selective beta-blockers for preventing decompensation in compensated cirrhosis and clinically significant portal hypertension (CSPH; HVPG≥10mmHg). Blood biomarkers were measured at baseline and at 1 and 2 years in patients who remained compensated and had available samples (n=164). Values of patients with CSPH were split at each time point by decompensation development in the next time interval after sampling. We also included 54 patients with cirrhosis and subclinical portal hypertension (PH) and 35 controls. We assessed inflammation markers (interleukin-6 [IL-6], tumor necrosis factor-alpha, von Willebrand factor [vWF], C-reactive protein), macrophage activation (CD14, CD163), intestinal barrier integrity (fatty acid-binding protein [FABP], haptoglobin), and bacterial translocation (lipopolysaccharide [LPS]). ResultsIL-6, CD163, and vWF were higher (p<0.01) at baseline in patients with cirrhosis and CSPH compared to those with subclinical PH and controls. IL-6 increased (p<0.05) at 1-year in CSPH patients, with a greater rise in those who developed decompensation. CD163 was higher (p<0.01) in patients who decompensated at baseline and 1- and 2-year. FABP was elevated (p<0.01) in CSPH patients compared to subclinical PH and controls at baseline and 1 year, while haptoglobin was lower (p<0.01). LPS was higher (p<0.01) in CSPH patients than in those with subclinical PH and controls and increased at 1-year regardless of decompensation development. ConclusionsInflammation and bacterial products are present in the systemic circulation in compensated cirrhosis with CSPH. Progressive inflammation precedes the first decompensation.

Clarification of a unique mucosal vaccination route for improved systemic and mucosal immune response in broiler

There are often outbreaks of infectious diseases on farms, which not only disrupt production but also cause significant economic losses. Vaccines are given to prevent the spread of these infectious diseases, but they produce only systemic antibodies or antibodies in the mucosa of a particular system. So, a new mucosal vaccination route is needed where the vaccine will produce antibodies in the systemic circulation as well as in the mucosa of many systems. In our study, the cloaca was targeted because it is associated with the mucosa of many systems. Whole-mount and routine histological staining show both lymphatic nodules and diffuse lymphatic tissues in the lamina propria of cloaca. These lymphatic tissues are made up of Bu-1+ B-cells, CD3+ T-cells, and KUL01+ macrophages and monocytes. So, this is a new mucosa-associated lymphoid tissue, named cloaca-associated lymphoid tissue (CALT). The CALT contains antigen-presenting cells (dendritic cells, macrophages, B cells, MHC II molecules, and T cells) and is equipped with blood vessels and high endothelial venules, which indicate its functional status. More antibodies were produced in the treatment group compared to the vehicle control group after administration of the infectious bursal disease (IBD) and the Newcastle disease (ND) vaccine through cloaca. In addition, the cloaca-associated route produces a higher number of antibodies than the other traditional routes, which reveals the uniqueness of this route. Cloacal-vaccinated chickens showed less damage to the follicle and epithelium of the bursa of Fabricius compared to other groups, indicating its lower cytotoxic effect. Therefore, the cloaca-associated mucosal vaccination route produces more antibodies than other mucosal vaccination routes, which will protect the chickens on the farm to a greater extent.

Comparative intrafollicular and plasma iron, ferritin, and transferrin concentrations in cycling mares

Background and Aim: In females of various species and experimental animals, iron (Fe) status in follicular fluid (FF) is associated with local physiological reproductive events related to follicle development, steroidogenesis, and oocyte maturation. However, these mechanisms remain unknown. This study aimed to determine and compare the intrafollicular and plasma concentrations of Fe, ferritin (Ferr), and transferrin (TRF) in cycling mares. Materials and Methods: Sixty ovaries were collected during the breeding season from 30 clinically normal mares raised for slaughterhouse meat production. Blood samples were collected before slaughter. Follicles were classified into three categories according to size: Small (20–30 mm; n = 20), medium (≥31–40 mm; n = 20), and large (≥41 mm; n = 20). The FF samples, after collection, were immediately taken to the laboratory for processing and were centrifuged, and the Fe and Ferr concentrations in the supernatant and plasma were determined by spectrophotometry. Results: Although intrafollicular Fe and Ferr were similar to plasma, TRF was significantly higher in FF than in systemic circulation (p &lt; 0.05). Follicular development does not modify the status of Fe in the mare. Conclusion: Based on this evidence, it is possible that the acquisition of this molecule possibly originated from a local de novo source, whereas their diffusion through ultrafiltration does not play a relevant role. These results provide new scientific insights into the status of follicle Fe, suggesting its involvement in normal ovarian functions in mares. Keywords: ferritin, follicular fluid, iron, mare, transferrin.

Intraperitoneal administration of a thermogel combined with an anticancer agent for the prevention of peritoneal carcinomatosis in a pig model.

Surgeons may discover perioperative clinical situations associated with an increased risk of peritoneal carcinomatosis recurrence after primary resection. We developed a thermogel that can be used as a drug carrier to deliver an anticancer agent in the peritoneal cavity as a rescue solution. The spatial distribution of the thermogel and pharmacokinetics of chemotherapy have been studied in pigs. The safety of the thermogel was assessed based on the healing of bowel sutures. Nine pigs received gel with oxaliplatin at 130 mg/200mL (TG-Ox group), and 4 pigs received the gel alone (TG group). Digestive tract and bladder wounds were made and sutured. Pigs were sacrificed at different times after surgery to monitor the distribution of the thermogel and to detect the occurrence of bowel fistulas. Oxaliplatin plasma and tissue concentrations were determined via mass spectrometry. After 3h, 100% of the regions of interest were covered by the gel, 78% were covered after 2 days, and 38% were covered after 4 days. The thermogel delayed the release of oxaliplatin into the systemic circulation and significantly prolonged tissue impregnation. Anastomotic fistulas were observed in the TG-Ox group (10%) versus 0% in the TG group (p=0.31). A homogeneous distribution of the thermogel throughout the peritoneal cavity was observed, and the thermogel fulfilled its functions as a drug carrier, including ensuring safety and delaying chemotherapy delivery. Treatment-induced toxicity due to oxaliplatin was identified. The concept of a rescue solution being available in operating rooms was demonstrated.

Design of experimental section of a water tunnel for simulation of heat dissipation condition of seawater-activated battery

Abstract A water tunnel is a crucial experimental apparatus in hydrodynamic research, as the traditional water tunnel has drawbacks such as a small cross-sectional area of the test section and higher costs, which makes it difficult to meet the requirements of a water tunnel for simulating the heat dissipation conditions of the seawater-activated battery. This paper proposes a water tunnel specifically designed for simulating the heat dissipation conditions of seawater-activated batteries, and the water tunnel consists of an external cooling water circulation system and an internal electrolyte circulation system. The experimental section’s design determines the water tunnel’s size and key technical indexes. The temperature distribution contour maps of the experimental section were obtained using Ansys Fluent software simulation. The cooling effect was analyzed, and a cooling water flow rate of 10 m/s was selected. Pressure and velocity contour maps were obtained by simulating the experimental section of the water tunnel. The results show that when the cooling water velocity is 10 m/s, the pressure drop of the experimental section is approximately 1.76 atmospheres. The flow field is uniform and stable, and the heat dissipation power can reach 45.5 kW, meeting the technical requirements.

Prolonged Skin Retention of Luliconazole from SLNs Based Topical Gel Formulation Contributing to Ameliorated Antifungal Activity.

The development of effective therapy is necessary because the patients have to contend with long-termtherapy as skin fungal infections usually relapse and are hardly treated. Despite being a potent antifungal agent, luliconazole (LCZ) has certainshortcomings such as limited skin penetration, low solubility in aqueous medium, and poor skin retention. Solid Lipid Nanoparticles (SLNs) were developed using biodegradable lipids by solvent injection method and were embodied into the gel base for topical administration. After in-vitro characterizations of the formulations, molecular interactions of the drug with excipients were analyzed using in-silico studies. Ex-vivo release was determined in contrast to the pure LCZ and the commercial formulation followed by in-vivo skin localization, skin irritation index, and antifungal activity. The prepared SLNs have an average particle size of 290.7nm with no aggregation of particles and homogenous gels containing SLNs with ideal rheology and smooth texture properties were successfully prepared. The ex-vivo LCZ release from the SLN gel was lower than the commercial formulation whereas its skin deposition and skin retention were higher as accessed by CLSM studies. The drug reaching the systemic circulation and the skin irritation potential were found to be negligible. Thesolubility and drug retention in the skin were both enhanced by the development of SLNs as a carrier. Thus, SLNs offer significant advantages by delivering long lasting concentrations of LCZ at the site of infection for a complete cure of the fungal load together with skin localization of the topical antifungal drug.

Physiological and behavioural implications of the portosystemic shunt in C57Bl/6J mice.

A significant fraction of the popular inbred C57Bl/6J mice show structural and biochemical features of the congenital portosystemic shunt (PSS). How this hepatic abnormality affects physiological and behavioural parameters has not been explored in detail. Here, we confirmed the frequent occurrence of the PSS in C57Bl/6J mice by three different methods. We screened a cohort of 119 C57Bl/6J mice for total bile acids (TBA) in plasma, identified 11 animals (9.2%) with high TBA (>11µm; 171.1 ± 76.8µm), and confirmed PSS presence in that subset by magnetic resonance angiography and 1H-magnetic resonance spectroscopy of brain metabolites in the hippocampal area. In addition to the high glutamine and low myo-inositol levels, we detected lower levels of several neurotransmitters and metabolites in the hippocampus, higher brain weight and volume, as well as enhanced brain glucose utilisation in the PSS mice. We also observed differences in peripheral organ weights, haematological cell counts and clinical chemistry parameters in C57Bl/6J mice with and without PSS. Animals with PSS were slightly hyperlocomotive, had better balance on the rotarod, showed altered gait properties, and displayed attenuated fear memory in the fear conditioning test. Furthermore, we revealed a significant alteration of the pharmacokinetic profile of diazepam in C57Bl/6J mice with PSS. Our data support previous reports of hepatic disturbances and demonstrate an altered neurobiological phenotype in C57Bl/6J mice with PSS. Such congenital differences between inbred C57Bl/6J littermates may significantly distort experimental outcomes of pharmacological, behavioural and genetic studies. KEY POINTS: A significant proportion of C57Bl/6J mice, an inbred strain popular in preclinical research, have congenital portosystemic shunts (PSS) that allow venous blood to enter systemic circulation bypassing the liver. In this study, we extended existing knowledge of PSS consequences, particularly with respect to the effects on brain structure and function. We demonstrated that C57Bl/6J mice with PSS differ from their normal counterparts in brain size and contents of several neuroactive substances, as well as in peripheral organ weights, rate of glucose utilisation, blood cell counts and blood clinical chemistry parameters. C57Bl/6J mice with PSS showed altered locomotor behaviour, performed worse in a memory test and had abnormal blood pharmacokinetics of a benzodiazepine drug after a single administration. PSS presence may significantly complicate the interpretation of experiments in C57Bl/6J mice; therefore, we propose that before their use in biomedical studies, these mice should be screened with a simple blood test.

Lipoic acid-locked reduction-responsive core-cross-linked micelles delivering paclitaxel for triple-negative breast cancer treatment

Most anti-tumor agents suffer from systemic non-specific distribution and low aggregation in tumors, which not only decreases the therapeutic efficacy, but also causes systemic toxic side effects in the treatments of tumors. In recent years, the rapid development of nanotechnology has brought new ideas for the application of anti-tumor drugs. Nanomedicines, such as liposomes and micelles, can improve drug targeting and prolong systemic circulation time to promote anti-tumor efficacy and reduce toxic side effects. However, conventional micelles bear the risk of instability and premature drug leaking in the blood circulation. We designed a reduction-responsive core-cross-linked micelle PTX@Fmoc-LA-PEG efficiently encapsulating Paclitaxel (PTX) via π-π stacking and hydrophobic interactions of Fmoc and PTX. Moreover, the micelle was further locked based on the cross-linking properties of the disulfide bonds formed by lipoic acid (LA). As expected, the core-cross-linked micelles PTX@Fmoc-LA-PEG remained stable in normal physiological environments, while restoring the normal drug release rate of micelles under the highly reducing environment due to LA unlocking. The blank micelles (Fmoc-LA-PEG) exhibited excellent biocompatibility, while the drug-loaded micelles (PTX@Fmoc-LA-PEG) displayed a remarkable anti-tumor effect in vitro and in vivo experiments. These results suggested that core-cross-linked micelles PTX@Fmoc-LA-PEG have great potential to improve the targeting and stability of anti-tumor drugs.

The Role of Next-Generation Sequencing (NGS) in the Relationship between the Intestinal Microbiome and Periprosthetic Joint Infections: A Perspective.

Periprosthetic joint infections are still a challenge in orthopedics and traumatology. Nowadays, genomics comes to the aid of diagnosis and treatment, in addition to traditional methods. Recently, a key role of the intestinal microbiota has been postulated, and great efforts are aimed at discovering its interconnection, which shows to be at different levels. Firstly, the gut microbiome influences the immune system through the gut-associated lymphoid tissue (GALT). A balanced microbiome promotes a strong immune response, which is essential to prevent all local and systemic infections, including PJI. Thus, a dysbiosis, i.e., the disruption of this system, leads to an imbalance between the various strains of microorganisms co-existing in the gut microbiome, which can result in a weakened immune system, increasing susceptibility to infections, including PJI. Additionally, the dysbiosis can result in the production of pro-inflammatory mediators that enter the systemic circulation, creating a state of chronic inflammation that can compromise the immune system's ability to fend off infections. Furthermore, the microbiome maintains the integrity of the gut barrier, preventing the translocation of harmful bacteria and endotoxins into the bloodstream; dysbiosis can compromise this protective "wall". In addition, the gut microbiome may harbor antibiotic-resistance genes; during antibiotic treatment for other infections or prophylaxis, these genes may be transferred to pathogenic bacteria, making the treatment of PJI more difficult. In this complex landscape, next-generation sequencing (NGS) technology can play a key role; indeed, it has revolutionized the study of the microbiome, allowing for detailed and comprehensive analysis of microbial communities. It offers insights into the functional potential and metabolic capabilities of the microbiome, studies the collective genome of the microbiome directly from environmental samples sequencing DNA without isolating individual organisms, analyzes the RNA transcripts to understand gene expression and functional activity of the microbiome, analyzes the RNA transcripts to understand gene expression and functional activity of the microbiome, investigates the metabolites produced by the microbiome and studies the entire set of proteins produced by the microbiome. NGS technology, the study of the micromyoma and its implications in the field of orthopedic trauma are innovative topics on which few publications are yet to be found in the international scientific literature. The costs are still high, the focus of research is maximum, and it will certainly change our approach to infections. Our study is an up-to-date review of the hot topic application of NGS in the study and investigation of periprosthetic infections and the microbiome.

دراسة عملية لاداء سخان ماء شمسي ذو الدوران الطبيعي المتصل على التوالي

This research paper presents an experimental study on the performance of a natural circulation solar water heater system with two typical collectors connected in series. The paper provides a comprehensive analysis of the system's thermal performance under different load conditions, including no-load, intermittent, and continuous load. Mean storage tank, solar collector means plate (the left) temperature and thermosyphon flow rate in a vertical tank were measured. Results showed that there was variation in solar water tank and collector plate temperature under load and no-load conditions. Analysis of thermal performance of the system was conducted for each condition. The highest plate temperature (100 ˚C or even more) with no circulation of both collector and load conditions, indicate the high quality of the solar collectors even during the cold season. The collector’s arrangement in series connection is of highest gain in energy and higher storage tank mean water temperature. Several characteristic equations obtained to represent the performance of the present natural circulation system under collector connection arrangement in series. In fact, when large amount of hot water was required for a certain purpose (Industrial sector for example - MSF plant or central heating), multiple collectors are to be deployed in series and in parallel to produce the required amount (quantity) and desired temperature (quality) at the same time. Key words: Thermosyphon solar water heater, storage tank profile temperature, Solar Water Heaters (SWHs), instantaneous efficiency, collector flow factor, collector efficiency factor, collector heat removal factor

Numerical Modelling of a Pulsating Flow Generator for Simulating Blood Pressure

Abstract Hypertension is a leading risk factor that deserves to be taken seriously, therefore researches on blood pressure measurement play a critical role. In this work, a liquid-operated pulsating flow circulation system with a bionic arm is set as a blood pressure simulator and a related numerical model is built to analyse the flow under different settings. The motion patterns of the flow generator and the medium used are two of the main factors discussed in this work. By comparing the pressure curves under different conditions and actual experimental data, the numerical model is validated, and so as to find the suitable parameters of the actual system.

The changing characteristics of torrential rainfall in the Huaihe River Basin from 1961 to 2020

Abstract The Huaihe River Basin (HRB) is one of the most severely affected regions by torrential rain disasters in China. However, with climate warming, it is unclear what new features torrential rain exhibits and how the main modes of torrential rain change in this region. This study analyzes the first two modes of torrential rain in the HRB from 1961 to 2020 and their driving factors. Results show that in the last 30 years, the frequency of torrential rain events in the HRB has clearly increased, especially in southern HRB region during the flood season. The first mode of torrential rain is an entire basin-wide mode, with a period of 2–3 years. The mode is primarily influenced by the low-level westerly jet stream and Jianghuai cyclones, which are closely linked to the stratospheric Quasi-Biennial Oscillation (QBO) through influencing planetary wave propagation and convective activity under different phases of QBO. The second mode is a north-south distribution mode, with a period of 4–6 years. The leading circulation system is the frontal systems. Both the East Asia/Pacific (EAP) teleconnection wave train and ENSO drive the second torrential rain mode. During El Niño years, anomalous subsidence and anticyclone in the western tropical Pacific, induced by sea surface temperature warming in the eastern tropical Pacific through the East Asia/Pacific teleconnection, can trigger the EAP wave train poleward in the East Asian region. This wave train leads to the cold-warm confrontation conducive to the second torrential rain mode.

Deep learning-aided temporal downscaling of GRACE-derived terrestrial water storage anomalies across the Contiguous United States

The Gravity Recovery And Climate Experiment (GRACE) and GRACE-FollowOn (GRACE(−FO)) satellites have been monitoring Earth’s changes in terrestrial water storage (TWS) or surficial mass changes at monthly sampling and a spatial scale longer than ∼330 km (half wavelength) over the past two decades. At monthly sampling or revisit time, the use of satellite gravimetry is difficult to effectively monitor abrupt extreme weather events which are high-frequency, including the climate-induced hurricanes/cyclones, flash floods and droughts. The majority of the contemporary studies have focused on satellite gravimetry spatial downscaling, and not on reducing the temporal resolution of Earth’s mass change. Here, we developed a Deep Learning (DL) algorithm to downscale monthly GRACE/ GRACE(−FO) Mass Concentration (Mascon) TWS anomaly (TWSA) solutions to daily sampling over the Contiguous United States (CONUS), with the aim of monitoring rapidly evolving natural hazard episodes. The simulative performance of the DL algorithm is validated by comparing the modeling to an independent observation and the land hydrology model (LHM) predicted TWSA. To confirm that our daily and monthly simulations captured the climatic variations, we first compared our simulations with El Niño/La Niña Southern Oscillation (ENSO) circulation system index, which has a dominant climatological and socioeconomic impact across CONUS, and results reveal high correlations which are statistically significant. Next, we assessed the feasibilities to detect long- and short-term variations in the TWSA signals triggered by hydrological extremes, including the 2011 and 2019 Missouri River Floods, the August 2017 Atlantic Hurricane Harvey landfalls in Texas, the 2012–2017 drought in California, and the flash drought in the Northern Great Plains in 2017. Additional validation results using independent in situ observations reveal that our DL-aided gravimetry downscaled daily simulations are capable of elucidating hazards and water cycle evolutions at high temporal resolution.

Investigation of mechanical performance for tricuspid valve stent in different compression modes

Abstract The tricuspid acting as a one-way valve between the right atrium and the right ventricle of the human heart, is very important for the blood circulation system. The regurgitation will be induced if the tricuspid cannot close normally, leading to symptoms such as arrhythmia and right heart failure. In the case of severe regurgitation, replacement with an artificial tricuspid valve instead of the natural tricuspid is the promising solution. For the typical artificial tricuspid valve, the bioprosthesis valve is fixed on a tricuspid valve stent which is usually compressed before being implanted into the heart. In this study, numerical simulation with an ABAQUS standard approach is carried out with a focus on the compression process of the tricuspid valve stent to evaluate the mechanical performances of two compression methods: one is the traditional radial compression method (RCM), and another is the axial compression method (ACM) that gradually compresses through a conical channel. The results indicate that the environment temperature is closely related to the stress distribution for both the RCM and ACM, in particular, a lower temperature can result in lower stress. The maximum strain is located at the inner corner of the joint of the stent ribs and the connection between the top arm and the stent, with a value over 12% at the temperature of 0°C, indicating the possible position for failure. The average diameter-stress curves of the RCM and ACM are respectively obtained for the compression process. To achieve long operation time, the RCM is recommended from the perspective of reducing compressive stress. The present study can provide the experience for the production and clinical application of tricuspid valve stents.

Pyrite trace metal and sulfur isotopic compositions track metalliferous fluid circulation within the Ordovician/Silurian organic-rich black shales in the eastern Sichuan Basin, southwestern China

Depicting metalliferous fluid flows in sedimentary basins has a remarkable implication for understanding the formation and evolution of organic-rich sediments. The Middle-Upper Yangtze region in South China hosts voluminous gaseous hydrocarbons and MVT-type ZnPb deposits. Natural gases are mainly distributed in the Sichuan Basin, yet ZnPb deposits are found in surrounding regions of the basin. Such a unique distribution pattern implies that the interplay between metalliferous fluids and organic-rich sediments may be extensive in the boundary of these two types of deposits. A typical Ordovician/Silurian (Wufeng/Longmaxi formations) organic-rich black shale outcrop occurs in the eastern boundary of the Sichuan Basin. Pyrites are frequently distributed across this section, providing an ideal opportunity to investigate features of metalliferous fluids and their potential impacts on organic-rich sediments. Pyrites associated with high-angle carbonate veinlets are recognized in the studied area, and this group of pyrites (“Group 2”) commonly display planar-laminated morphologies, moderate δ34S values (0.78 ‰–8.86 ‰), and elevated trace metal contents (Ni, Pb, Mn, Mo, Tl, and REE) than those not associated with carbonate veinlets. These features suggest that this group of pyrites may be precipitated via local metalliferous fluid flows. Besides, pyrites with relatively lower trace metal contents can be further divided into two groups, including a group of euhedral/subhedral pyrites with more depleted δ34S values (−18.06 ‰ – -1.15 ‰; “Group 1”) and a group of planar-laminated/cubic pyrites with enriched δ34S values (10.55 ‰–37.62 ‰; “Group 3”). Pyrites of Group 1 and Group 3 may be formed via bacterial sulfate reduction (BSR) and thermochemical sulfate reduction (TSR), respectively. The discovery of fluid-related, trace-metal-enriched pyrites implies that fluid circulation within organic-rich black shales has the potential to remobilize, transport, and re-deposit trace metals. Besides, metalliferous fluid may also promote organic matter maturation within the Sichuan Basin. The outcomes of this study, combined with previous findings of metalliferous fluid flows in the center of the basin and ZnPb mineralization belts surrounding the basin, imply that a widespread Ediacaran-Palaeozoic fluid circulation system may exist in the Middle-Upper Yangtze region.

Does rising land price promote the circulation industry development? An analysis of internet-based moderating effects

With the rapid development of the Internet, digital technology is increasingly integrating into the modern circulation system. The influence mechanisms of land prices on the development of the circulation industry are gradually transforming. Using data from 104 major cities in China from 2003 to 2021, this study uses the panel two-way fixed effects model, moderating effects model and threshold regression method to examine the mechanisms by which land prices affect the circulation industry development and the moderating role of Internet development. The results show that elevated land prices significantly stimulate the growth of the circulation industry, leading to an expansion in the circulation industry scale, optimization of its structure, and enhancement of its facilities. The findings remain robust even after addressing endogeneity concerns and conducting various robustness tests. Moreover, the impact of high land prices on the circulation industry is more pronounced in small and medium-sized cities group as well as central region cities group. Real estate investment and industrial structure upgrading are the key channels through which high land prices promote the development of the circulation industry. Additionally, Internet development has a positive moderating effect on the promotion that high land prices stimulate the development of the circulation industry. Notably, only when Internet development surpasses a certain threshold that the promotional effect of land prices on the circulation industry development be fully realized. Based on the above conclusions, the government should continue to deepen the market-oriented reform of land elements, implement precise industrial policy support for the circulation industry and promote circulation digital transformation.