Recent progresses in the development of tubular segmented-in-series solid oxide fuel cells:Experimental and numerical study

Solid oxide fuel cells(SOFCs)have attracted a great deal of interest because they have the highest efficiency without using any noble metal as catalysts among all the fuel cell technologies.However,traditional SOFCs suffer from having a higher volume,current leakage,complex connections,and difficulty in gas sealing.To solve these problems,Rolls-Royce has fabricated a simple design by stacking cells in series on an insulating porous support,resulting in the tubular segmented-in-series solid oxide fuel cells(SIS-SOFCs),which achieved higher output voltage.This work systematically reviews recent advances in the structures,preparation methods,perform-ances,and stability of tubular SIS-SOFCs in experimental and numerical studies.Finally,the challenges and future development of tubular SIS-SOFCs are also discussed.The findings of this work can help guide the direction and inspire innovation of future development in this field.

From concept to commercialization:A review of tubular solid oxide fuel cell technology

The reduced sealing difficulty of tubular solid oxide fuel cells(SOFCs)makes the stacking of tubular cell groups relatively easy,and the thermal stress constraints during stack operation are smaller,which helps the stack to operate stably for a long time.The special design of tubular SOFC structures can completely solve the problem of high-temperature sealing,especially in the design of multiple single-cell series integrated into one tube,where each cell tube is equivalent to a small electric stack,with unique characteristics of high voltage and low current output,which can significantly reduce the ohmic polarization loss of tubular cells.This paper provides an overview of typical tubular SOFC structural designs both domestically and internationally.Based on the geometric structure of tubular SOFCs,they can be divided into bamboo tubes,bamboo flat tubes,single-section tubes,and single-section flat tube structures.Meanwhile,this article provides an overview of commonly used materials and preparation methods for tubular SOFCs,including commonly used materials and preparation methods for support and functional layers,as well as a comparison of commonly used preparation methods for microtubule SOFCs,It introduced the three most important parts of building a fuel cell stack:manifold,current collector,and ceramic adhesive,and also provided a detailed introduction to the power generation systems of different tubular SOFCs,Finally,the development prospects of tubular SOFCs were discussed.

Polar-coordinate line-projection light-curing continuous 3D printing for tubular structures

3D printing techniques offer an effective method in fabricating complex radially multi-material structures.However,it is challenging for complex and delicate radially multi-material model geometries without supporting structures,such as tissue vessels and tubular graft,among others.In this work,we tackle these challenges by developing a polar digital light processing technique which uses a rod as the printing platform.The 3D model fabrication is accomplished through line projection.The rotation and translation of the rod are synchronized to project and illuminate the photosensitive material volume.By controlling the distance between the rod and the printing window,we achieved the printing of tubular structures with a minimum wall thickness as thin as 50 micrometers.By controlling the width of fine slits at the printing window,we achieved the printing of structures with a minimum feature size of 10 micrometers.Our process accomplished the fabrication of thin-walled tubular graft structure with a thickness of only 100 micrometers and lengths of several centimeters within a timeframe of just 100 s.Additionally,it enables the printing of axial multi-material structures,thereby achieving adjustable mechanical strength.This method is conducive to rapid customization of tubular grafts and the manufacturing of tubular components in fields such as dentistry,aerospace,and more.

Effect of Types and Orders of Electromagnetic Field Finite Element Meshes on Power Communication Harmonic Parameters Calculation Results of Tubular Hydrogenerators

In generator design field,waveform total harmonic distortion(THD)and telephone harmonic factor(THF)are parameters commonly used to measure the impact of generator no-load voltage harmonics on the power communication quality.Tubular hydrogenerators are considered the optimal generator for exploiting low-head,high-flow hydro resources,and they have seen increasingly widespread application in China's power systems recent years.However,owing to the compact and constrained internal space of such generators,their internal magnetic-field harmonics are pronounced.Therefore,accurate calculation of their THD and THF is crucial during the analysis and design stages to ensure the quality of power communication.Especially in the electromagnetic field finite element modeling analysis of such generators,the type and order of the finite element meshes may have a significant impact on the THD and THF calculation results,which warrants in-depth research.To address this,this study takes a real 34 MW large tubular hydrogenerator as an example,and establishes its electromagnetic field finite element model under no-load conditions.Two types of meshes,five mesh densities,and two mesh orders are analyzed to reveal the effect of electromagnetic field finite element mesh types and orders on the calculation results of THD and THF for such generators.

Tubular Heat Enhancement Using Twisted Tape Inserts with Large Holes

Heat augmentation techniques play a vital role in the heating and cooling processes in industries,including solar collectors and many applications that utilize heat exchangers.Several studies are based on inserting fillers inside the tubes to enhance heat transfer.This investigation considered the effects of twisted tapes with large holes on a tubular heat exchanger’s(HX)heat transmission,pressure drop,and thermal boosting factor.In the experimental section,counter-swirl flow generators used twisted tapes with pairs of 1.0 cm-diameter holes and changes in porosity(Rp)at 1.30%and 2.70%.In the experiments,air was utilized as a working fluid in a tube with a circular cross-section.The turbulent flow was considered,with Reynolds numbers(Re)domain from 4800 to 9500,and a boundary condition with a uniform wall heat flux was constructed.The findings expound that when the number of holes rose,the Nusselt number(Nu),the factor of friction(f),and the thermal enhancement factor(η)all increased as well.Additionally,as the friction factor increased,the Nusselt number of the tape-equipped tube was noticeably higher.Additionally,it was discovered that the friction factor was between 70%and 94%lower than the values of the tube without tape,while the(Nu)was between 87%and 97%higher than the conventional tube values.The maximum value ofηis 89%.According to the experimental results,empirical correlations for Nu,f,andηwere also generated.

Reliability of neutrophil gelatinase-associated lipocalin in detecting acute tubular necrosis in decompensated cirrhosis:Systematic review and meta-analysis

BACKGROUND Acute kidney injury(AKI)in cirrhosis is common.The diagnosis of AKI in cirrhosis patients depends on clinical presentation and laboratory tests like serum creatinine.However,urine biomarkers could also be used to assess the type of AKI and the severity of the disease.We performed a systematic review with metaanalysis to evaluate the association with urine neutrophil gelatinase-associated lipocalin(NGAL)marker in identifying acute tubular necrosis(ATN)in patients with cirrhosis.AIM To assess the reliability of urine NGAL in the detection of ATN in patients with cirrhosis.METHODS We systematically searched MEDLINE and PubMed using keywords including“urine biomarkers”,“NGAL”,“kidney dysfunction”,and“cirrhosis”to identify relevant studies.Data was screened and extracted.Included studies assessed hospitalized cirrhosis patients with AKI using the urine NGAL biomarker.We synthesized the data using diagnostic odds ratio(DOR),comparative and descriptive analyses,and Cochran Mantel-Haenszel(CMH)statistics to evaluate heterogeneity.RESULTS Three thousand seven hundred and one patients with cirrhosis were analyzed from a total of 21 cohort studies.The DOR of 14 of those studies[pooled DOR:22.150,(95%CI:17.58-27.89),P<0.0001]demonstrated a significant association between urine NGAL levels and its identification of ATN.Following stratification by cirrhosis status,heterogeneity was analyzed and showed a significant non-zero correlation between NGAL and AKI(CMH statistic=702.19,P<0.0001).CONCLUSION In patients with cirrhosis,the use of urine NGAL is a reliable biomarker for detecting ATN and identifying the etiology of AKI.

Clinical efficacy and safety of double-channel anastomosis and tubular gastroesophageal anastomosis in gastrectomy

BACKGROUND With the continuous progress of surgical technology and improvements in medical standards,the treatment of gastric cancer surgery is also evolving.Proximal gastrectomy is a common treatment,but double-channel anastomosis and tubular gastroesophageal anastomosis have attracted much attention in terms of surgical options.Each of these two surgical methods has advantages and disadvantages,so it is particularly important to compare and analyze their clinical efficacy and safety.AIM To compare the surgical safety,clinical efficacy,and safety of double-channel anastomosis and tubular gastroesophageal anastomosis in proximal gastrectomy.METHODS The clinical and follow-up data of 99 patients with proximal gastric cancer who underwent proximal gastrectomy and were admitted to our hospital between January 2018 and September 2023 were included in this retrospective cohort study.According to the different anastomosis methods used,the patients were divided into a double-channel anastomosis group(50 patients)and a tubular gastroesophageal anastomosis group(49 patients).In the double-channel anastomosis,Roux-en-Y anastomosis of the esophagus and jejunum was performed after proximal gastric dissection,and then side-to-side anastomosis was performed between the residual stomach and jejunum to establish an antireflux barrier and reduce postoperative gastroesophageal reflux.In the tubular gastroesophageal anastomosis group,after the proximal end of the stomach was cut,tubular gastroplasty was performed on the distal stump of the stomach and a linear stapler was used to anastomose the posterior wall of the esophagus and the anterior wall of the stomach tube.The main outcome measure was quality of life 1 year after surgery in both groups,and the evaluation criteria were based on the postgastrectomy syndrome assessment scale.The greater the changes in body mass,food intake per meal,meal quality subscale score,and total measures of physical and mental health score,the better the condition;the greater the other indicators,the worse the condition.The secondary outcome measures were intraoperative and postoperative conditions,the incidence of postoperative long-term complications,and changes in nutritional status at 1,3,6,and 12 months after surgery.RESULTS In the double-channel anastomosis cohort,there were 35 males(70%)and 15 females(30%),33(66.0%)were under 65 years of age,and 37(74.0%)had a body mass index ranging from 18 to 25 kg/m2.In the group undergoing tubular gastroesophageal anastomosis,there were eight females(16.3%),21(42.9%)individuals were under the age of 65 years,and 34(69.4%)had a body mass index ranging from 18 to 25 kg/m2.The baseline data did not significantly differ between the two groups(P>0.05 for all),with the exception of age(P=0.021).The duration of hospitalization,number of lymph nodes dissected,intraoperative blood loss,and perioperative complication rate did not differ significantly between the two groups(P>0.05 for all).Patients in the dual-channel anastomosis group scored better on quality of life measures than did those in the tubular gastroesophageal anastomosis group.Specifically,they had lower scores for esophageal reflux[2.8(2.3,4.0)vs 4.8(3.8,5.0),Z=3.489,P<0.001],eating discomfort[2.7(1.7,3.0)vs 3.3(2.7,4.0),Z=3.393,P=0.001],total symptoms[2.3(1.7,2.7)vs 2.5(2.2,2.9),Z=2.243,P=0.025],and other aspects of quality of life.The postoperative symptoms[2.0(1.0,3.0)vs 2.0(2.0,3.0),Z=2.127,P=0.033],meals[2.0(1.0,2.0)vs 2.0(2.0,3.0),Z=3.976,P<0.001],work[1.0(1.0,2.0)vs 2.0(1.0,2.0),Z=2.279,P=0.023],and daily life[1.7(1.3,2.0)vs 2.0(2.0,2.3),Z=3.950,P<0.001]were all better than those of the tubular gastroesophageal anastomosis group.The group that underwent tubular gastroesophageal anastomosis had a superior anal exhaust score[3.0(2.0,4.0)vs 3.5(2.0,5.0),Z=2.345,P=0.019]compared to the dual-channel anastomosis group.Hemoglobin,serum albumin,total serum protein,and the rate at which body mass decreased one year following surgery did not differ significantly between the two groups(P>0.05 for all).CONCLUSION The safety of double-channel anastomosis in proximal gastric cancer surgery is equivalent to that of tubular gastric surgery.Compared with tubular gastric surgery,double-channel anastomosis is a preferred surgical technique for proximal gastric cancer.It offers advantages such as less esophageal reflux and improved quality of life.

Self-assembly synthesis of phosphorus-doped tubular g-C_(3)N_(4);Ti_(3)C_(2)MXene Schottky junction for boosting photocatalytic hydrogen evolution

Establishing highly effective charge transfer channels in carbon nitride(g-C_(3)N_(4)) to enhance its photocatalytic activity is still a challenging issue.Herein,the delaminated 2D Ti_(3)C_(2) MXene nanosheets were employed to decorate the P-doped tubular g-C_(3)N_(4)(PTCN)for engineering 1D/2D Schottky heterojunction(PTCN/TC)through electrostatic self-assembly.The optimized PTCN/TC exhibited the highest hydrogen evolution rate(565 μmol h^(-1)g^(-1)),which was 4.3 and 2.0-fold higher than pristine bulk g-C_(3)N_(4) and PTCN,respectively.Such enhancement may be primarily attributed to the phosphorus heteroatom doped and unique structure of 1D/2D g-C_(3)N_(4)/Ti_(3)C_(2) Schottky heterojunction,enhancing the light-harvesting and charges’separation.One-dimensional pathway of g-C_(3)N_(4) tube and built-in electric field of interfacial Schottky effect can significantly facilitate the spatial separation of photogenerated charge carriers,and simultaneously inhibit their recombination via Schottky barrier.In this composite,metallic Ti_(3)C_(2) was served as electrons sink and photons collector.Moreover,ultrathin Ti_(3)C_(2) flake with exposed terminal metal sites as a co-catalyst exhibited higher photocatalytic reactivity in H2 evolution compared to carbon materials(such as reduced graphene oxide).This work not only proposed the mechanism of tubular g-C_(3)N_(4)/Ti_(3)C_(2) Schottky junction in photocatalysis,but also provided a feasible way to load ultrathin Ti_(3)C_(2) as a co-catalyst for designing highly efficient photocatalysts.

Dynamic Analysis and Parametric Optimization of Telescopic Tubular Mast Applied on Solar Sail

Large-scale solar sails can provide power to spacecraft for deep space exploration.A new type of telescopic tubular mast(TTM)driven by a bistable carbon fiber-reinforced polymer tube was designed in this study to solve the problem of contact between the sail membrane and the spacecraft under light pressure.Compared with the traditional TTM,it has a small size,light weight,high extension ratio,and simple structure.The anti-blossoming and self-unlocking structure of the proposed TTM was described.We aimed to simplify the TTM with a complex structure into a beam model with equal linear mass density,and the simulation results showed good consistency.The dynamic equation was derived based on the equivalent model,and the effects of different factors on the vibration characteristics of the TTM were analyzed.The performance parameters were optimized based on a multiobjective genetic algorithm,and prototype production and load experiments were conducted.The results show that the advantages of the new TTM can complete the deployment of large-scale solar sails,which is valuable for future deep space exploration.

Recent applications and chiral separation development based on stationary phases in open tubular capillary electrochromatography(2019–2022)

Capillary electrochromatography(CEC)plays a significant role in chiral separation via the double separation principle,partition coefficient difference between the two phases,and electroosmotic flow-driven separation.Given the distinct properties of the inner wall stationary phase(SP),the separation ability of each SP differs from one another.Particularly,it provides large room for promising applications of open tubular capillary electrochromatography(OT-CEC).We divided the OT-CEC SPs developed over the past four years into six types:ionic liquids,nanoparticle materials,microporous materials,biomaterials,non-nanopolymers,and others,to mainly introduce their characteristics in chiral drug separation.There also added a few classic SPs that occurred within ten years as supplements to enrich the features of each SP.Additionally,we discuss their applications in metabolomics,food,cosmetics,environment,and biology as analytes in addition to chiral drugs.OT-CEC plays an increasingly significant role in chiral separation and may promote the development of capillary electrophoresis(CE)combined with other instruments in recent years,such as CE with mass spectrometry(CE/MS)and CE with ultraviolet light detector(CE/UV).

Albumin-bound kynurenic acid is an appropriate endogenous biomarker for assessment of the renal tubular OATs-MRP4 channel

Renal tubular secretion mediated by organic anion transporters(OATs)and the multidrug resistanceassociated protein 4(MRP4)is an important means of drug and toxin excretion.Unfortunately,there are no biomarkers to evaluate their function.The aim of this study was to identify and characterize an endogenous biomarker of the renal tubular OATs-MRP4 channel.Twenty-six uremic toxins were selected as candidate compounds,of which kynurenic acid was identified as a potential biomarker by assessing the protein-binding ratio and the uptake in OAT1-,OAT3-,and MRP4-overexpressing cell lines.OAT1/3 and MRP4 mediated the transcellular vectorial transport of kynurenic acid in vitro.Serum kynurenic acid concentration was dramatically increased in rats treated with a rat OAT1/3(rOAT1/3)inhibitor and in rOAT1/3 double knockout(rOAT1/3^(-/-))rats,and the renal concentrations were markedly elevated by the rat MRP4(rMRP4)inhibitor.Kynurenic acid was not filtered at the glomerulus(99%of albumin binding),and was specifically secreted in renal tubules through the OAT1/3-MRP4 channel with an appropriate affinity(Km)(496.7 mM and 382.2 mM for OAT1 and OAT3,respectively)and renal clearance half-life(t1/2)in vivo(3.7±0.7 h).There is a strong correlation in area under the plasma drug concentration-time curve(AUC0et)between cefmetazole and kynurenic acid,but not with creatinine,after inhibition of rOATs.In addition,the phase of increased kynurenic acid level is earlier than that of creatinine in acute kidney injury process.These results suggest that albumin-bound kynurenic acid is an appropriate endogenous biomarker for adjusting the dosage of drugs secreted by this channel or predicting kidney injury.

Seismic behavior of steel tubular bridge columns equipped with low-yield-point steel plates in the root replaceable pier

To enable rapid recovery of a steel bridge column after an earthquake,a novel tubular-section steel bridge column equipped with low-yield-point(LYP)steel tubular plates in the root replaceable pier is proposed.For the purpose of discussing the seismic behavior of the novel steel bridge column,quasi-static tests and finite element simulation analyses of the specimens were carried out.The effects of parameters such as the axial compression ratio,eccentricity,and thickness and material strength of the tubular plate in the energy-dissipating zone are discussed.Experimental results from seven specimens that were subjected to four failure modes are presented.The damage to the quasi-static specimens is localized to the replaceable energy-dissipating pier.The seismic behavior of the novel steel bridge columns is significantly influenced by the axial compression ratio and eccentricity of specimens.Numerical results show that the high stress area of the specimens is mainly concentrated in the connection zone between the LYP steel tubular plate and the bottom steel plate,which is consistent with the position of the quasi-static specimen when it was prone to fracture.Finally,a calculation formula is proposed to facilitate the capacity prediction of this new steel tubular bridge column under repeated loading.

ELABELA protects against diabetic kidney disease by activating high glucose-inhibited renal tubular autophagy

ELABELA(ELA),an endogenous ligand of the apelin receptor(also known as apelin peptide jejunum[APJ]),has been shown to decrease in the plasma of patients with diabetic kidney disease(DKD).In the current study,we explored the potential function as well as the underlying mechanisms of ELA in DKD.We first found that the ELA levels were decreased in the kidneys of DKD mice.Then,we found that ELA administration mitigated renal damage and downregulated the expression of fibronectin,collagenⅣ,and transforming growth factor-β1 in the db/db mice and the high glucose cultured HK-2 cells.Furthermore,the autophagy markers,Beclin-1 and LC3-Ⅱ/LC3-Ⅰratio,were significantly impaired in DKD,but the ELA treatment reversed these alterations.Mechanistically,the inhibitory effects of ELA on the secretion of fibrosis-associated proteins in high glucose conditions were blocked by pretreatment with 3-methyladenine(an autophagy inhibitor).In summary,these in vivo and in vitro results demonstrate that ELA effectively protects against DKD by activating high glucose-inhibited renal tubular autophagy,potentially serving as a novel therapeutic candidate for DKD.

Compressive Strength of Tubular Members with Combined Pitting Corrosion and Crack Damage

Tubular members subject to combined pitting corrosion and crack damage were numerically studied to clarify the reduction of ultimate strength and failure behavior,based on numerical models validated against available experi-ments.The effects of length,location and inclined angle of a crack under combined damage were studied to disclose the mechanism of interaction between the crack and corrosion pits.The methods,named as linear superposition directly accumulating the effects of solo crack and solo pitting damage,as well as crack projection transferring an inclined crack to a transverse one,were discussed and verified in the view of assessing ultimate strength of tubular members with combined damage.It was shown that the former is practical but complex while the next always over-estimates the residual strength.Besides,the location and inclined angle of a crack have a subtle effect on the reduction of ultimate strength under combined damage,especially at higher level of pitting damage,due to the synergistic effect between corrosion pits and cracks.Such effect can lead to early occurrence of plasticity and local buckling by inducing stress interaction between crack tips and pits,and causing more significant strength reduction compared with a solo type of damage.A practical method was proposed to determine the loss ratio of cross-sectional area on the equivalent weakest section of a damaged member.Based on the loss ratio,a formula was presented to predict the ultimate strength of damaged members with combined damage,showing good applicability.

Decreased TRPM7 alleviates high glucose-induced renal tubular epithelial cell injury by inhibiting the HMGB1/TLR4 signaling pathway

Objective:To explore the regulatory mechanism of transient receptor potential melastatin-7(TRPM7)in high glucose-induced renal tubular epithelial cell injury.Methods:The expression of TRPM7 in the serum of diabetic nephropathy patients and high glucose-induced HK-2 cells was detected by RT-qPCR.Then,the TRPM7 interference vector was constructed,and the downstream high mobility group box 1(HMGB1)/Toll-like receptor 4(TLR4)signaling pathway proteins were detected.Next,in addition to interference with TRPM7 expression,overexpression of HMGB1 in high glucose-induced HK-2 cells was performed.Cell activity,apoptosis,oxidative stress levels,and inflammation levels were determined by CCK8,TUNEL,Western blotting,immunofluorescence and related kits.Results:TRPM7 expression was upregulated in the serum of diabetic nephropathy patients and high glucose-induced HK-2 cells.Interference with TRPM7 reduced cell damage,epithelial-mesenchymal transition,oxidative stress,and inflammatory response in high glucose-induced HK-2 cells via inhibiting the HMGB1/TLR4 signaling pathway.However,the effects induced by TRPM7 silencing were abrogated by HMGB1 overexpression.Conclusions:Decreased TRPM7 alleviates high glucose-induced renal tubular epithelial cell injury by inhibiting the HMGB1/TLR4 signaling pathway.Further animal experiments and clinical trials are warranted to verify its effect.

Analysis of inhomogeneity of solidified microstructure of continuous casting copper tubular billet based on factor analysis

The horizontal continuous casting process,the initial step in TP2 copper tubular processing,directly determines the microstructure and properties of copper tubular.However,the process parameters of the continuous casting characterize time variation,multiple disturbances and strong coupling.As a consequence,their influence on a casting billet is difficult to be determined.Due to the above issues,the common factor and special factor analysis of the factor analysis model were used in this study,and the casting experiment and billet metallographic experiment were carried out to diagnose and analyze the reason of the microstructure inhomogeneity.The multiple process parameters were studied and classified using common factor analysis,2 the cast billets with abnormal microstructures were identified by GT^(2) statistics,and the most important factors affecting the microstructural homogeneity were found by special factor analysis.The calculated and experimental results show that the principal parameters influencing the inhomogeneity of solidified microstructure are the primary inlet water pressure and the primary outlet water temperature.According to the consequence of the above investigation,the inhomogeneity of the copper billet microstructure can be effectively improved when the process parameters are controlled and adjusted.

Incomplete distal renal tubular acidosis uncovered during pregnancy:A case report

BACKGROUND Renal tubular acidosis(RTA)is a renal cause of non-anion-gap metabolic acidosis characterized by low urinary ammonia excretion.This condition has a low prevalence,and various congenital and acquired etiologies.To date,only a few cases of idiopathic RTA uncovered during pregnancy have been reported.CASE SUMMARY A previously healthy 32-year-old Korean woman at 30 wk of gestation was admitted to Pusan National University Hospital with preterm labor.At admission,the patient presented with hypokalemia,non-anion-gap metabolic acidosis,and nephrocalcinosis.Distal RTA was diagnosed based on laboratory blood and urine findings and imaging examinations.Various tests,including next-generation gene sequencing panels for nephropathy,were performed to determine the etiology of the disease,which indicated that it was idiopathic.The patient received sodium bicarbonate and potassium chloride supplementation.After 3 wk,she delivered a baby who was subsequently diagnosed with corpus callosum agenesis and colpocephaly.During regular follow-ups for 6 mo postpartum,her hypokalemia and metabolic acidosis were gradually resolved,and medications eventually discontinued.CONCLUSION Herein we describe a case of idiopathic distal RTA discovered during pregnancy.Hypokalemia and metabolic acidosis resolved spontaneously after delivery.

Renal calcification in children with renal tubular acidosis:What a paediatrician should know

Renal tubular acidosis(RTA)can lead to renal calcification in children,which can cause various complications and impair renal function.This review provides pediatricians with a comprehensive understanding of the relationship between RTA and renal calcification,highlighting essential aspects for clinical manage-ment.The article analyzed relevant studies to explore the prevalence,risk factors,underlying mechanisms,and clinical implications of renal calcification in children with RTA.Results show that distal RTA(type 1)is particularly associated with nephrocalcinosis,which presents a higher risk of renal calcification.However,there are limitations to the existing literature,including a small number of studies,heterogeneity in methodologies,and potential publication bias.Longitudinal data and control groups are also lacking,which limits our understanding of longterm outcomes and optimal management strategies for children with RTA and renal calcification.Pediatricians play a crucial role in the early diagnosis and management of RTA to mitigate the risk of renal calcification and associated complications.In addition,alkaline therapy remains a cornerstone in the treatment of RTA,aimed at correcting the acid-base imbalance and reducing the formation of kidney stones.Therefore,early diagnosis and appropriate therapeutic interventions are paramount in preventing and managing renal calcification to preserve renal function and improve long-term outcomes for affected children.Further research with larger sample sizes and rigorous methodologies is needed to optimize the clinical approach to renal calcification in the context of RTA in the pediatric population.

Clinical, Etiological and Progressive Aspects of Acute Tubular Necrosis of Toxic Origin at the Brazzaville University Hospital Center

Background and Objectives: Acute tubular necrosis (ATN) is the second cause of acute kidney injury (AKI) in an intra-hospital environment. The toxic origin is avoidable. Our objectives were to determine the toxic substances at the origin of ATN at the Brazzaville University Hospital and determine the evolving aspects and the factors associated with it. Patients and Methods: We carried out a 12-month from June 20, 2022 to June 30, 2023. It was a prospective observational study in the Nephrology Department of Brazzaville University Hospital Center. The diagnosis of ATN was done in the presence of AKI occurring in the context of taking nephrotoxic substances with negative albuminuria. Cases of ATN aggravating CKD were excluded. Data analysis was done with Epi-Info 7.2 software. Results: We identified 63 cases of AKI on toxic ATN. Their average age was 47 ± 19 years with a male predominance of 60.2%. The 3 main toxicants incriminated were: herbal medicine (49.2%), Gentamycin (17.5%) and non-steroidal anti-inflammatory drugs (14.3%). An indication for hemodialysis was made in 43 patients (68.2%), the evolution was marked by a cure in 29 patients (46.1%), 10 (15.9%) became chronic kidney failure, 19 (30.1%) died, 5 (7.9%) were lost to follow-up. The main factor for non-healing is anuria (p Conclusion: The main cause of toxic ATN at Brazzaville University Hospital is herbal medicine. The death rate is high there.

EXPERIMENTAL RESEARCH AND NONLINEAR FINITE ELEMENT ANALYSIS ON NEW TYPE JOINT BETWEEN COLUMN AND STEEL BEAM OF CONCRETE-FILLED RECTANGULAR STEEL TUBULAR

Experimental results of new type joints between the column and the. steel beam of concrete-filled rectangular steel tubular （CFRT） under reversed cyclic loads are presented. The earthquake resistant capacity of the joint is influenced by infilled concrete, stiffener length and relative dimensions of column and beam. It is found that the hysteresis curves obtained in the experiment are full and the joints have a good energy dissipation capacity. The nonlinear finite element models are also used to analyze the hysteresis behavior of the joints under reversed cyclic loads using ANSYS 8.0. The influences of the stiffener length and the infilled concrete are analyzed. Analytical results show that the stiffener length and the infilled concrete are critical for the joints. Furthermore, the skeleton curves of the finite element models are in good agreement with those of experiments.