Critical assessment of the reported bidirectional associations between gallstone, non-alcoholic fatty liver, and kidney stone diseases

The recent article by Jiang et al published in World Journal of Gastroenterology reports substantial bidirectional associations between gallstone disease(GSD),non-alcoholic fatty liver disease(NAFLD),and kidney stone disease(KSD),based on multicenter cross-sectional studies and a systematic review with meta-analysis.While the findings have the potential to significantly impact clinical and pre-ventive strategies,several methodological issues merit closer examination.This letter critiques key aspects of the study,including sample population hetero-geneity,potential confounding variables,and the reliance on cross-sectional data that may limit causal inferences.We also discuss the generalizability of these results to broader populations given the study's focus on the Chinese demogra-phic.By addressing these concerns,we suggest a more nuanced interpretation of the associations between GSD,NAFLD,and KSD,advocating for longitudinal studies to validate these findings and enhance their applicability in global health contexts.

Clip-stone and T clip-sinus post laparoscopic biliary surgery:Two case reports and review of the literature

BACKGROUND Laparoscopic cholecystectomy(LC)and laparoscopic common bile duct exploration(LCBDE)are widely used in gallbladder and biliary tract diseases.During these procedures,vessels or tissues are commonly ligated using clips.However,postoperative migration of clips to the common bile duct(CBD)or Ttube sinus tract is an overlooked complication of laparoscopic biliary surgery.Previously,most reported cases of postoperative clip migration involved metal clips,with only a few cases involving Hem-o-lok clips and review of the literature.CASE SUMMARY This report describes two cases in which Hem-o-lok clips migrated into the CBD and the T-tube sinus tract following laparoscopic surgery.Case 1 is a 68-year-old female admitted due to abdominal discomfort,and two Hem-o-lok clips were found to have migrated into the CBD 17 months after LC and LCBDE with T-tube drainage,and were removed using a stone extraction balloon.The patient was discharged smoothly after recovery.Case 2 is a 74-year-old male who underwent LC and LCBDE with T-tube drainage and laparoscopic biliary tract basket stone extraction.Nine weeks postoperatively,following T-tube removal,a Hem-o-lok clip was found in the sinus tract,and was extracted from the T-tube sinus tract.The patient recovered smoothly postoperatively.This study also reviews the literature from 2013 to July 2024 on using Hem-o-lok clips in LC and/or LCBDE treatment of gallbladder and biliary diseases and the postoperative migration of these clips into the CBD,T-tube sinus tract,or duodenum.CONCLUSION In patients with a history of LC and/or LCBDE,clip migration should be considered as a differential diagnosis.

Tectonic modes of mantle convection and their implications for Earth's tectonic evolution based on three-dimensional numerical simulations

Five tectonic modes of mantle convection are obtained and analyzed with three-dimensional numerical models in a spherical shell domain.The five tectonic convective modes are non-plate mobile-lid,plate-like mobile-lid,episodic plate-like mobile-lid,episodic stagnant-lid,and stagnant-lid convective modes,respectively.The typical characteristics of these five tectonic modes and their numerical classification criteria based on plateness,mobility,and their standard deviations are presented and discussed.The results show that the yield stress of the lithosphere has profound effects on the tectonic convective modes.With the gradual increase of yield stress,the tectonic mode of mantle convection changes from one to another sequentially through the aforementioned five modes.Additionally,as the Rayleigh number increases,the range of yield stress for the platelike mobile-lid convective mode decreases,and the dimensionless transition stress between different tectonic modes increases.Specifically,the dimensional transition stress between the non-plate mobile-lid convective mode and plate-like mobile-lid convective mode increases with the increase of Rayleigh number,but decreases between other tectonic modes.Furthermore,we find that the transition stress between different tectonic modes is inversely proportional to the internal heating rate,with the transition stress decreasing as the internal heating rate increases.The fitting analysis of the transition stress between tectonic modes shows that Earth's current plate tectonics correspond to a lithospheric yield stress of 150–250 MPa,which aligns with the strength of serpentinized mantle rock determined by experimental petrography.If the Archean mantle was 300℃warmer than it is today,then the Earth was in an episodic stagnant-lid convective mode.The tectonic evolution of the Earth's surface is closely related to the lithospheric strength and the process of thermal evolution.If the lithospheric strength was only 150 MPa,plate tectonics in the early mantle rapid cooling model would have begun before 3.8 Ga,and plate tectonics in the late mantle rapid cooling model would have begun at approximately 1.5 Ga.However,at a lithospheric strength of 200 MPa,plate tectonics in the late mantle rapid cooling model would have begun later than 0.95 Ga,and plate tectonics in the early mantle rapid cooling model would have begun at approximately 2 Ga.The early Earth was in the episodic stagnant-lid convective mode,which means that subduction might still have occurred at that time.The presence of the episodic plate-like mobile-lid convective mode in Earth's later history indicates that there might also have been intermittent surface stagnation during plate tectonics,which may provide an explanation for the quiet period of tectonic activity at approximately 1.0 Ga on Earth.This indicates that tectonic inactivity during a geological period is not an indicator that plate tectonics did not begin.

Mechanical Properties of Railway High-strength Manufactured Sand Concrete: Typical Lithology, Stone Powder Content and Strength Grade

In order to achieve the large-scale application of manufactured sand in railway high-strength concrete structure,a series of high-strength manufactured sand concrete(HMC)are prepared by taking the manufactured sand lithology(tuff,limestone,basalt,granite),stone powder content(0,5%,10%,15%)and concrete strength grade(C60,C80,C100)as variables.The evolution of mechanical properties of HMC and the correlation between cubic compressive strength and other mechanical properties are studied.Compared to river sand,manufactured sand enhances the cubic compressive strength,axial compressive strength and elastic modulus of concrete,while its potential microcracks weaken the flexural strength and splitting tensile strength of concrete.Stone powder content displays both positive and negative effects on mechanical properties of HMC,and the stone powder content is suggested to be less than 10%.The empirical formulas between cubic compressive strength and other mechanical properties are proposed.

Effects of the extrusion parameters on microstructure,texture and room temperature mechanical properties of extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy

Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusion speeds(3 and 6 mm/s).The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy,and the second phase showed streamline distribution along the extrusion direction(ED).With extrusion temperature increased from 260 to 320℃,the microstructure,texture,and mechanical properties of alloys changed slightly.The dynamic recrystallization(DRX)degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1,and the strength gradually decreased but elongation(EL)increased.With the extrusion speed increased from 3 to 6 mm/s,the grain sizes and DRX degree increased significantly,and the samples presented the typical<2111>-<1123>rare-earth(RE)textures.The alloy extruded at 260℃ with extrusion ratio of 10:1 and extrusion speed of 3 mm/s showed the tensile yield strength(TYS)of 213 MPa and EL of 30.6%.After quantitatively analyzing the contribution of strengthening mechanisms,it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening contributions.These results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.

PbrMYB4,a R2R3-MYB protein,regulates pear stone cell lignification through activation of lignin biosynthesis genes

Pear(Pyrus bretschneideri)fruit stone cells are primarily composed of lignin and have strongly lignified cell walls.The presence of stone cells has a negative influence on fruit texture and taste,and thus the reduction of stone cell content in pear fruit is a key goal of breeding efforts.However,research into the key transcription factors and regulatory networks associated with pear fruit stone cell formation have been limited.We here used a combination of co-expression network and expression quantitative trait locus(eQTL)analyses in 206 pear cultivars with different stone cell contents to identify relevant genes;these analyses uncovered the gene PbrMYB4,a R2R3 MYB transcription factor gene.There was a strong positive correlation between relative PbrMYB4 expression levels in the fruit flesh and stone cell/lignin contents.Overexpression of PbrMYB4 significantly increased the lignin contents,whereas silencing of PbrMYB4 had the opposite effect,decreasing the contents of lignin.PbrMYB4 overexpression in pear calli significantly promoted lignin biosynthesis.In Arabidopsis thaliana,PbrMYB4 overexpression resulted in increasing lignin deposition,cell wall thickness of vessels and xylary fiber,and accelerating expression level of lignin biosynthetic genes.PbrMYB4 was found to activate 4-Coumarate:Coenzyme A Ligase(Pbr4CL1)by binding to AC-I elements in the promoter regions,as demonstrated with dual-luciferase reporter assays and a yeast one-hybrid assay.These results demonstrated that PbrMYB4 positively regulated lignin biosynthesis in pear fruit stone cells by activating lignin biosynthesis genes.This study improves our understanding of the gene regulatory networks associated with stone cell formation in pear fruit,providing guidance for molecular breeding of pear varieties with low stone cell content.

Exploring the links between gallstone disease, non-alcoholic fattyliver disease, and kidney stones: A path to comprehensiveprevention

The recent study exploring the bidirectional associations between gallstone disease,non-alcoholic fatty liver disease,and kidney stone disease highlights a critical concern in chronic disease management.Given the rising global prevalence of these conditions,understanding their interconnections is essential.The study emphasizes the importance of shared risk factors,such as obesity,type 2 diabetes,dyslipidemia,and oxidative stress,and calls for multidisciplinary screening strategies.This approach would improve patient outcomes and reduce the socio-economic burden.While the study contributes valuable insights from a Chinese population,further research across diverse populations is necessary to validate and extend these findings globally.Ultimately,the research underscores the need for integrated prevention programs to better manage these interconnected diseases and improve health outcomes.

Extracorporeal shockwave lithotripsy in the management of urinary stones: New concepts and techniques to improve outcomes

Objective: Extracorporeal shockwave lithotripsy (SWL) currently plays an important role in the treatment of urinary tract lithiasis. The purpose of this article was to describe new concepts and procedural strategies that would improve results using SWL as a treatment for urolithiasis, thereby achieving better clinical practice.Methods: A systematic review process was carried in PubMed/PMC from January 2003 to March 2023. A narrative synthesis of the most important aspects has been made.Results: The important recommendations for the adequate selection of the candidate patient for treatment with SWL are summarized, as well as the new strategies for a better application of the technique. Aspects about intraoperative position, stone localization and monitoring, analgesic control, machine and energy settings, and measures aiming at reduced risk of complications are described.Conclusion: To achieve the therapeutic goal of efficient stone disintegration without increasing the risk of complications, it is necessary to make an adequate selection of patients and to pay special attention to several important factors in the application of treatment. Technological development in later generation devices will help to improve current SWL results.

Oxalate regulates crystal-cell adhesion and macrophage metabolism via JPT2/PI3K/AKT signaling to promote the progression of kidney stones

Oxalate is an organic dicarboxylic acid that is a common component of plant foods.The kidneys are essential organs for oxalate excretion,but excessive oxalates may induce kidney stones.Jupiter microtubule associated homolog 2(JPT2)is a critical molecule in Ca^(2+)mobilization,and its intrinsic mechanism in oxalate exposure and kidney stones remains unclear.This study aimed to reveal the mechanism of JPT2 in oxalate exposure and kidney stones.Genetic approaches were used to control JPT2 expression in cells and mice,and the JPT2 mechanism of action was analyzed using transcriptomics and untargeted metabolomics.The results showed that oxalate exposure triggered the upregulation of JPT2,which is involved in nicotinic acid adenine dinucleotide phosphate(NAADP)-mediated Ca^(2+)mobilization.Transcriptomic analysis revealed that cell adhesion and macrophage inflammatory polarization were inhibited by JPT2 knockdown,and these were dominated by phosphatidylinositol 3-kinase(PI3K)/AKT signaling,respectively.Untargeted metabolomics indicated that JPT2 knockdown inhibited the production of succinic acid semialdehyde(SSA)in macrophages.Furthermore,JPT2 deficiency in mice inhibited kidney stones mineralization.In conclusion,this study demonstrates that oxalate exposure facilitates kidney stones by promoting crystal-cell adhesion,and modulating macrophage metabolism and inflammatory polarization via JPT2/PI3K/AKT signaling.

Note on:“Ballistic model for the prediction of penetration depth and residual velocity in adobe:A new interpretation of the ballistic resistance of earthen masonry”

A recently published modeling approach for the penetration into adobe and previous approaches implicitly criticized are reviewed and discussed.This article contains a note on the paper titled“Ballistic model for the prediction of penetration depth and residual velocity in adobe:A new interpretation of the ballistic resistance of earthen masonry”(DOI:https://doi.org/10.1016/j.dt.2018.07.017).Reply to the Note from Li Piani et al is linked to this article.

Ecological environmental quality evaluation and driving factor analysis of the Lijiang River Basin,based on Google Earth Engine

For regional ecological management,it is important to evaluate the quality of ecosystems and analyze the underlying causes of ecological changes.Using the Google Earth Engine(GEE)platform,the remote sensing ecological index(RSEI)was calculated for the Lijiang River Basin in Guangxi Zhuang Autonomous Region for 1991,2001,2011,and 2021.Spatial autocorrelation analysis was employed to investigate spatiotemporal variations in the ecological environmental quality of the Lijiang River Basin.Furthermore,geographic detectors were used to quantitatively analyze influencing factors and their interaction effects on ecological environmental quality.The results verified that:1)From 1991 to 2021,the ecological environmental quality of the Lijiang River Basin demonstrated significant improvement.The area with good and excellent ecological environmental quality in proportion increased by 19.69%(3406.57 km^(2)),while the area with fair and poor ecological environmental quality in proportion decreased by 10.76%(1860.36 km^(2)).2)Spatially,the ecological environmental quality of the Lijiang River Basin exhibited a pattern of low quality in the central region and high quality in the periphery.Specifically,poor ecological environmental quality characterized the Guilin urban area,Pingle County,and Lingchuan County.3)From 1991 to 2021,a significant positive spatial correlation was observed in ecological environmental quality of the Lijiang River Basin.Areas with high-high agglomeration were predominantly forests and grasslands,indicating good ecological environmental quality,whereas areas with low-low agglomeration were dominated by cultivated land and construction land,indicating poor ecological environmental quality.4)Annual average precipitation and temperature exerted the most significant influence on the ecological environmental quality of the basin,and their interactions with other factors had the great influence.This study aimed to enhance understanding of the evolution of the ecological environment in the Lijiang River Basin of Guangxi Zhuang Autonomous Region and provide scientific guidance for decision-making and management related to ecology in the region.

Effects of Desalination Processes on the Water Circulation and Earth System

Desalination is emerging as a promising alternative among various technologies to resolve water shortage. However, desalination requires a sufficient energy and cooling device and therefore poses limitations for its installation and application. In particular, many countries suffering water deficits are economically underdeveloped and cannot afford the technology. As this technology, which changes seawater into freshwater, has little environmental impact, developed countries will need to assist less developed countries to introduce this technology as a humanitarian effort. This will help reduce the number of countries that have experienced difficulty with development.

Comparison of the clinical effects of dual-modality endoscopy and traditional laparotomy for the treatment of intra-and extrahepatic bile duct stones

BACKGROUND Bile duct stones(BDSs)may cause patients to develop liver cirrhosis or even liver cancer.Currently,the success rate of surgical treatment for intrahepatic and extrahepatic BDSs is not satisfactory,and there is a risk of postoperative complic-ations.AIM To compare the clinical effects of dual-modality endoscopy(duodenoscopy and laparoscopy)with those of traditional laparotomy in the treatment of intra-and extrahepatic BDSs.METHODS Ninety-five patients with intra-and extrahepatic BDSs who sought medical services at Wuhan No.1 Hospital between August 2019 and May 2023 were selected;45 patients in the control group were treated by traditional laparotomy,and 50 patients in the research group were treated by dual-modality endoscopy.The following factors were collected for analysis:curative effects,safety(incision infection,biliary fistula,lung infection,hemobilia),surgical factors[surgery time,intraoperative blood loss(IBL)volume,gastrointestinal function recovery time,and length of hospital stay],serum inflammatory markers[tumor necrosis factor(TNF)-α,interleukin(IL)-6,and IL-8],and oxidative stress[glutathione peroxidase(GSH-Px),superoxide dismutase(SOD),malondialdehyde(MDA),and advanced protein oxidation products(AOPPs)].RESULTS The analysis revealed markedly better efficacy(an obviously higher total effective rate)in the research group than in the control group.In addition,an evidently lower postoperative complication rate,shorter surgical duration,gastrointestinal function recovery time and hospital stay,and lower IBL volume were observed in the research group.Furthermore,the posttreatment serum inflammatory marker(TNF-α,IL-6,and IL-8)levels were significantly lower in the research group than in the control group.Compared with those in the control group,the posttreatment GSH-Px,SOD,MDA and AOPPs in the research group were equivalent to the pretreatment levels;for example,the GSH-Px and SOD levels were significantly higher,while the MDA and AOPP levels were lower.CONCLUSION Dual-modality endoscopy therapy(duodenoscopy and laparoscopy)is more effective than traditional laparotomy in the treatment of intra-and extrahepatic BDSs and has a lower risk of postoperative complications;significantly shortened surgical time;shorter gastrointestinal function recovery time;shorter hospital stay;and lower intraop-erative bleeding volume,while having a significant inhibitory effect on excessive serum inflammation and causing little postoperative oxidative stress.

Factors and Cut-Off Predicting Stone Passage under Medical Expulsive Therapy (MET)

Background: Ureteral stones are the most common leading cause of acute flank pain. This study aimed to identify sociodemographic and clinical variables predicting spontaneous ureteral stone passage and determine the optimal size cut-off for predicting such passage. Method: We conducted a retrospective evaluation of patients presenting with acute renal colic at a urology outpatient clinic. Patients with ureteral stones ≤ 10 mm and no surgical intervention post-initial diagnosis, who attended follow-up visits, were included. Exclusion criteria comprised stone size > 1 cm, fever due to obstructive pyelonephritis, acute kidney injury, single kidney status, or bilateral ureteral obstruction. Results: Of 124 included patients, the spontaneous stone passage rate was 57.3%, with a mean passage time of 11.1 (SD 6.25) days. Bivariate analysis revealed that factors predicting spontaneous passage were stone size (p Conclusions: Stone size < 7 mm, UVJ or distal ureter location, emerged as key predictors of stone passage in nephrolithiasis, and stone size below 6.85 mm is a reasonable cut off to initiate MET rather than 10 mm.

Epidemiologic, Diagnostic, and Therapeutic Features of Urinary Stone Disease in Northern Benin from 2018 to 2023

Objective: To determine the epidemiologic, diagnostic, and therapeutic features of urinary in northern Benin from 2018 to 2023. Patients and Method: The study was an observational and descriptive one. We exhaustively and retrospectively collected data from the medical records of the patients that were managed from February 1, 2018 to February 1, 2023 at the Department of Surgery of “Centre Hospitalier Universitaire Départmental Borgou-Alibori or CHUD-BA”. Results: Among the 4522 patients managed, 75% or 1.7% had urinary stone disease. Their mean age was 41 years. The sex ratio was 2.75, the males being predominantly affected. Of the 75 cases of urinary stone disease, 30.7% (n = 23) were renal, 46.7% (n = 35) were ureteral, and 22.7% (n = 17) were vesical. The patients came from variable geographical areas, ethnic groups, and professional sectors. Their main complaints were pain (57.3%), hematuria (14.7%), dysuria (12%), and fever (5.3%). 15 (20%) patients, i.e., 7 renal stone and 8 ureteral stone patients, had an obstructive renal failure. The imaging tools available were ultrasonography, tomography and computed tomographic scan. 11 of the bladder stone cases (64.7%) were associated with a bladder outlet obstruction. Overall, 38.7% of the patients had either diabetes mellitus (6.7%), hypertension or high blood pressure (6.7%), benign prostate hyperplasia (8%), urinary schistosomiasis (6.7%), ureteral pelvic junction obstruction (2.7%), and prostate cancer (1.3%). Of the 19 patients whose dietary behavior was investigated 15 (79%), 11 (57.9%) et 11 (57.9%) demonstrated a diet which was respectively rich in milk, fromage and meat. 100% of bladder stones were removed through cystolithotomy. Renal stones were removed by pyelolithtomy (52.2%) and nephrolithotomy (21.7%). Ureteral stones were removed through ureterolithotomy (40%), expelled by means of alpha-blockers (40%) or managed with ureteral pigtail stent (20%). Conclusion: The hospital prevalence of urinary stone disease was 1.7%. The mean age in urinary stone-affected patients was 41 years. The urinary stone predominantly affected male patients: the sex ratio was 2.75. The stones were mainly removed through open surgery.

Interrelationships between Length of the Day, Moon Distance, Phanerozoic Geodynamic Cycles, Tidal Dissipation and Earth’s Core: Review and Analysis

The rotation of the Earth and the related length of the day (LOD) are predominantly affected by tidal dissipation through the Moon and the growth of the Earth’s core. Due to the increased concentration of mass around the rotation axis of the spinning Earth during the growth of the core the rotation should have been accelerated. Controversially the tidal dissipation by the Moon, which is mainly dependent on the availability of open shallow seas and the kind of Moon escape from a nearby position, acts towards a deceleration of the rotating Earth. Measurements of LOD for Phanerozoic and Precambrian times open ways to solve questions concerning the geodynamical history of the Earth. These measurements encompass investigations of growth patterns in fossils and depositional patterns in sediments (Cyclostratigraphy, Tidalites, Stromatolites, Rhythmites). These patterns contain information on the LOD and on the changing distance between Earth and Moon and can be used as well for a discussion about the growth of the Earth’s core. By updating an older paper with its simple approach as well as incorporating newly published results provided by the geoscientific community, a moderate to fast growth of the core in a hot early Earth will be favored controversially to the assumption of a delayed development of the core in an originally cold Earth. Core development with acceleration of Earth’s rotation and the contemporaneous slowing down due to tidal dissipation during the filling of the ocean may significantly interrelate.

Control of Earth system evolution on the formation and enrichment of marine ultra-deep petroleum in China

Taking the Paleozoic of the Sichuan and Tarim basins in China as example,the controlling effects of the Earth system evolution and multi-spherical interactions on the formation and enrichment of marine ultra-deep petroleum in China have been elaborated.By discussing the development of“source-reservoir-seal”controlled by the breakup and assembly of supercontinents and regional tectonic movements,and the mechanisms of petroleum generation and accumulation controlled by temperature-pressure system and fault conduit system,Both the South China and Tarim blocks passed through the intertropical convergence zone(ITCZ)of the low-latitude Hadley Cell twice during their drifts,and formed hydrocarbon source rocks with high quality.It is proposed that deep tectonic activities and surface climate evolution jointly controlled the types and stratigraphic positions of ultra-deep hydrocarbon source rocks,reservoirs,and seals in the Sichuan and Tarim basins,forming multiple petroleum systems in the Ediacaran-Cambrian,Cambrian-Ordovician,Cambrian-Permian and Permian-Triassic strata.The matching degree of source-reservoir-seal,the type of organic matter in source rocks,the deep thermal regime of basin,and the burial-uplift process across tectonic periods collectively control the entire process from the generation to the accumulation of oil and gas.Three types of oil and gas enrichment models are formed,including near-source accumulation in platform marginal zones,distant-source accumulation in high-energy beaches through faults,and three-dimensional accumulation in strike-slip fault zones,which ultimately result in the multi-layered natural gas enrichment in ultra-deep layers of the Sichuan Basin and co-enrichment of oil and gas in the ultra-deep layers of the Tarim Basin.

Effect of Lateritic Stone Aggregate and Coconut Husk Fiber on the Properties of Concrete

Natural stone aggregate forms the bulk volume of concrete and has contributed to the increased cost of concrete production. This has led to the search for alternate aggregates such as lateritic stone for concrete production. This paper investigates the engineering properties of concrete produced with lateritic aggregate (LA) as the coarse aggregate replacement and coconut husk fibre (CHF) as reinforcement. Natural stone aggregate was replaced by LA at 0%, 10%, 20%, 30%, 40%, and 50%, with 0.25% constant CHF by weight. A mix proportion of 1:1.5:3 with a water-cement ratio of 0.6 was used for producing concrete. A total of 162 specimens (90 cubes and 72 beams) were prepared and tested at the 7, 14, 21, and 28 days of curing. The highest compressive strength was 43.36 N/mm2 (10% LA replacement) as compared to the control of 41.51 N/mm2. The 10% LA replacement obtained the highest flexural strength of 5.35 N/mm2 as compared with the 5.29 N/mm2 for the control. The water absorption of the concrete increased from 2.8% (control) to 3.57% (50% replacement LA). Scanning electron microscopy (SEM) revealed micro gaps between CHF and LA concrete. The study, therefore, concludes that the use of LA and CHF positively influenced the strength properties of concrete. 10% LA replacement of coarse aggregate and 0.25% CHF is recommended to practitioners for use.

Physical and Thermo-Mechanical Properties of Composite Materials Based on Raw Earth and Crushed Palm Leaf Fibers (Borassus aethiopum)

The objective of this study is to seek solutions to reduce the impact of buildings on climate change and to promote the use of local bio-sourced or geo-sourced materials for sustainable construction. Different samples of raw earth from 3 sites were taken in the commune of Mlomp. Geotechnical tests showed that the raw earth samples from sites 2 and 3 have more clay fraction while site 1 contains more sand. The fact of integrating fibers from crushed palm leaves (Borassus aethiopum) (2%, 4% and 6%) into the 3 raw earth samples reduced the mechanical resistance to compression and traction of the 3 raw earths. The experimental results of thermal tests on samples of earth mixtures with crushed Palma leaf fibers show a decrease in thermal conductivity as well as thermal effusivity as the percentages increase (2%, 4% and 6%) of fibers in raw earth for the 3 sites. This shows that this renewable composite material can help improve the thermal insulation of building envelopes.

Optimisation of Thermal Comfort of Building in a Hot and Dry Tropical Climate: A Comparative Approach between Compressed Earth/Concrete Block Envelopes

Compressed earth blocks (CEB) are an alternative to cement blocks in the construction of wall masonry. However, the optimal architectural construction methods for adequate thermal comfort for occupants in hot and arid environments are not mastered. This article evaluates the influence of architectural and constructive modes of buildings made of CEB walls and concrete block walls, to optimize and compare their thermal comfort in the hot and dry tropical climate of Ouagadougou, Burkina Faso. Two identical pilot buildings whose envelopes are made of CEB and concrete blocks were monitored for this study. The thermal models of the pilot buildings were implemented in the SketchUp software using an extension of EnergyPlus. The models were empirically validated after calibration against measured thermal data from the buildings. The models were used to do a parametric analysis for optimization of the thermal performances by simulating plaster coatings on the exterior of walls, airtight openings and natural ventilation depending on external weather conditions. The results show that the CEB building displays 7016 hours of discomfort, equivalent to 80.1% of the time, and the concrete building displays 6948 hours of discomfort, equivalent to 79.3% of the time. The optimization by modifications reduced the discomfort to 2918 and 3125 hours respectively;i.e. equivalent to only 33.3% for the CEB building and 35.7% for the concrete building. More study should evaluate thermal optimizations in buildings in real time of usage such as residential buildings commonly used by the local middle class. The use of CEB as a construction material and passive means of improving thermal comfort is a suitable ecological and economical option to replace cementitious material.