Located in Southeastern Chad. The Iro lake offers a great opportunity for the study of Precambrian formations and their Phanerozoic cover. Pluton is a Cal-alkaline granite. Due to its geographical location and geologi...Located in Southeastern Chad. The Iro lake offers a great opportunity for the study of Precambrian formations and their Phanerozoic cover. Pluton is a Cal-alkaline granite. Due to its geographical location and geological features, it holds crucial information for understanding the evolution of the Saharan Meta craton (central Africa), which remains poorly studied. One of the objectives is to map the formations Precambrian age in Southeastern Chad. Based on the petrographic and geochemical results, we identified granitoids of pan-African age (biotite granite, aplite granite and pegmatite granite). This Precambrian basement is covered with sedimentary formations (clays, argillites, lateritic cuirasses, etc.). The mineral assemblage is characteristic of acid rocks. Geochemistry reveals rocks with a high SiO2 range (62% - 77%) giving sub-alkaline to calc-alkaline acid rocks with high k (4.62% to 6.39%). The granitoids are classified as S-type hyperaluminous granites. This classification is supported by the presence of peraluminous minerals (e.g., muscovite) within the Iro granitoids, which also have high (>1%). Geochemical variation within the granites is largely due to extensive crystal fractionation. The Pattern of REEs normalized to the primitive mantle shows a pronounced negative Eu anomaly, reflecting the crystallization process and fractional crystallization of plagioclase in the rock, and a positive Yb anomaly. The role of plagioclase fractionation was relatively major during the earlier intrusive stages (consistent with the presence of Eu anomalies) and slightly increased, together with biotite and K-feldspar fractionation, during the later (granitic) rock crystallization. The Pattern of the spider normalized to MORBs shows two pronounced negative anomalies in TiO2 and Cs and a slight negative anomaly in Ba. The loss of Ba, Ti and Cs may be caused by the plagioclase fractionation, apatite and ilmenite crystal. The Ba anomaly is also controlled by the presence of K-feldspar and mica. The observed Ti anomalies are due to the fractionation of magnetite indicating a subduction environment (or remelting of a source from a subduction environment).展开更多
Two protected sites located on the outskirts of the Sena Oura National Park (PNSO) in West Mayo-Kebbi cover an area of 1800 m2 is pattern choose in pastoral enclave in both village. This study was undertaken to highli...Two protected sites located on the outskirts of the Sena Oura National Park (PNSO) in West Mayo-Kebbi cover an area of 1800 m2 is pattern choose in pastoral enclave in both village. This study was undertaken to highlight the floristic diversity of the herbaceous and woody vegetation on these sites in the offing to know the ability of charge into UBT that most support the park peripheral. It took place on two experimental sites on a natural course in two villages: Wazetelan and Massang. The approach used for the study was a survey using the systematic sampling method and a 30 m × 30 m plot. The survey consisted in listing all the taxa in a floristically homogeneous plot, each assigned the Braun-Blanquet dominance abundance coefficient. These surveys revealed a floristic richness of 73 species, 58 genera, including 46 herbaceous and 26 woody species. The Shannon result gives H1' = 0.12 bit for herbaceous species and H2' = 0.44 bit for woody species, meaning that the herbaceous and woody populations of all the surveys have a very low species diversity, as H' < 3 according to the Shannon index assessment threshold. Herbaceous species are divided into 13 families and 33 genera. The most represented families are Fabaceae (27.3%) and Poaceae (21.9%). Most of the other families (1.3%) have only one species, if any. Herbaceous species are divided into 33 genera grouped into 13 families. The most represented families are Fabaces (16 species), 34%, and Poaceae (12 species), 26%. The 26 woody species, most of which come from itinerant surveys, are distributed across 24 genera and 12 families, the most important of which is Fabaceae with 09 species (34.6%). This floristic assessment, in terms of quantity and quality, has enabled us to estimate the carrying capacity of the two pastoral enclaves in Dari and Goumadji cantons, and to guide the government’s actions with regard to rangeland management.展开更多
A total of fifty (50) samples of water from Lake Fitri (Chad), with 25 samples per island (Domoro and Maguite). The aim of this study was to analyze the bacteriological, biochemical and physico-chemical quality of the...A total of fifty (50) samples of water from Lake Fitri (Chad), with 25 samples per island (Domoro and Maguite). The aim of this study was to analyze the bacteriological, biochemical and physico-chemical quality of the water in Lake Fitri in Chad. Standard microbiology methods were used. Isolated strains of enterobacteria were characterized by API 20E and API Staph galleries and confirmed by API Web. Antibiotic resistance was performed according to the recommendations of the antibiogram committee (CA-SFM, 2019). Physico-chemical analysis of the water was carried out by (Rodier, 2009). The microbiological results revealed an abundance on the Domoro islands (5.37.106 ± 1.5.105 and 1.97.105 ± 4.94.104), successively for total aerobic mesophilic flora (FMAT), and thermotolerant coliform (E. coli) and on the Maguite Islands (4.71.106 ± 7.14.105 and 2.32.105 ± 2.86.104), alternately for total aerobic mesophilic flora (FMAT), and thermotolerant coliform (E. coli). The results obtained after incubation of the biochemical tests using the API 20E and API Staph galleries and their proposed numerical profile analyzed using Api software and confirmed by Api Web confirmed the contamination of the waters of Lake Fitri by pathogenic strains of E. coli, Staphylococcus and Salmonella spp. The results of the antibiogram carried out show the emergence of certain resistances to Tobramycin, Flucytosine and Teicoplanin. The average levels of BOD5, COD, SS, Nitrate (NO3) and Nitrite (NO2) for Domoro Island were 32.14 ± 2.37 mg/L, 423.86 ± 4.78 mg/L, 65.42 ± 2.27 mg/L, 0.04 ± 0.01 mg/L and 3.32 ± 1.48 mg/L respectively. The water from the islands of Lake Fitri must therefore be rigorously treated before consumption.展开更多
This study focuses on the thermophysical characterizations of composite materials made from polypropylene reinforced with residues and fibers from Borassus wood from Chad. These properties are experimentally determine...This study focuses on the thermophysical characterizations of composite materials made from polypropylene reinforced with residues and fibers from Borassus wood from Chad. These properties are experimentally determined at different temperatures using the hot wire method of the “FP2C” machine, where the hot wire probe is inserted between two specimens. The values of the thermal conductivity in powdered Borassus wood range from 0.170 W/mK to 0.182 W/mK for female wood (FNTF) and from 0.169 W/mK to 0.173 W/mK for male wood. For the female and male fibers, the thermal conductivity values range from 0.137 W/mK to 0.157 W/mK for the female and from 0.138 W/mK to 0.168 W/mK for the male. The thermal effusivity of the residues and fibers of Borassus wood varies from: 509.6 Ws1/2/m2K to 543 Ws1/2/m2K for the powder of female wood and from 524.6 Ws1/2/m2K to 547 Ws1/2/m2K for the powder of male wood. For the fibers of Borassus wood, the values range from 410.6 Ws1/2/m2K to 523.6 Ws1/2/m2K for the female wood fibers and from 420.3 Ws1/2/m2K to 480.3 Ws1/2/m2K for the male wood fibers. These results are important for the applications of Borassus wood residues and fibers in construction works regarding the thermal insulation of habitats.展开更多
Background: Social determinants of health (SDOH) significantly influence diseases with environmental components, like vector-borne parasitic diseases. This study aims to examine how these factors influence vector-born...Background: Social determinants of health (SDOH) significantly influence diseases with environmental components, like vector-borne parasitic diseases. This study aims to examine how these factors influence vector-borne parasitic diseases (VBPDs) transmission in Chad and provide recommendations for policy improvements. Methods: The study adopts the WHO Conceptual Framework of SDOH to compare two regions in Southern Chad: Kouh-Est, which has an ongoing vector control program, and Grand-Sido, which lacks such a program. The study includes both nomadic and sedentary populations to provide a comprehensive understanding of the SDOH influencing VBPDs. Households were randomly selected. Data on sociodemographic characteristics, literacy, knowledge of VBPDs and protective measures, and access to education and health facilities were collected. Results: A total of 202 households from 17 villages, including 820 participants, were surveyed. Agriculture, livestock, and fishing were the main occupations, involving 84.1% of participants. Literacy was low, with 36.7% non-educated, 47.7% completing primary school, 14.5% secondary school, and only 0.3% reaching tertiary education. Most villages lacked schools beyond the primary level, and nomadic populations were significantly less educated than sedentary ones (p Conclusion: Educational deficiencies, lack of protective measures against vectors, inadequate healthcare resources, and lifestyle conditions aggravated by poor road infrastructure, limited transportation, and economic constraints contribute to worsened VBPDs outcomes in these rural populations. Addressing these systemic issues in the surveyed communities is essential for improving health equity and VBPDs outcomes in these regions specifically and in similar populations settings more broadly.展开更多
目的：探讨心力衰竭高血压、年龄、糖尿病和脑卒中（包括一过性脑缺血）（CHADS2）评分及改良CHADS评分对心房颤动（房颤）射频消融术后复发的预测价值。方法对2010年7月至2012年3月在我院行射频消融术的93例房颤患者追踪随访12个月，术...目的：探讨心力衰竭高血压、年龄、糖尿病和脑卒中（包括一过性脑缺血）（CHADS2）评分及改良CHADS评分对心房颤动（房颤）射频消融术后复发的预测价值。方法对2010年7月至2012年3月在我院行射频消融术的93例房颤患者追踪随访12个月，术后1，3，6，9，12个月行12导联心电图或长程心电图检查，结合临床症状及心电图检查结果将其分为复发组（n＝40）和未复发组（n＝53），采用单因素和多因素分析消融术后房颤复发的危险因素。结果93例房颤患者中持续性房颤35例（37.63%），随访12个月时复发40例（43.01%）。房颤复发组与未复发组在平均年龄（P＜0.01）、年龄＞70岁（P＜0.05）、病史（P＜0.05）、房颤类型（P＜0.01）、左房内径（P＜0.001）、左室射血分数（P＜0.05）、血细胞比容（P＜0.05）、是否伴心力衰竭（P＜0.05）、是否伴高血压（P＜0.01）、是否伴糖尿病（P＜0.05）、是否有一过性脑缺血或脑卒中史（P＜0.05）、术后是否服用血管紧张素转换酶抑制剂和血管紧张素Ⅱ受体拮抗剂（ACEI/ARB，P＜0.01）、术后是否服用Ⅲ类抗心律失常药（P＜0.05）、CHADS2评分≥1（P＜0.001）等方面差异有统计学意义。logistic回归分析发现，病史、房颤类型、左房内径、CHADS2评分≥1为房颤术后复发的独立危险因素（病史长短：OR＝1.16，P＝0.020；左房内径：OR＝1.17，P＝0.025；房颤类型：OR＝3.34，P＝0.050；CHADS2评分≥1：OR＝5.93，P＝0.019）。进一步分析发现，CHADS2评分≥2、改良CHADS评分≥1、改良CHADS评分≥2亦为房颤术后复发的独立危险因素（CHADS2≥2：OR＝5.42，P＝0.028；改良CHADS评分≥1：OR＝6.64，P＝0.015；改良CHADS评分≥2：OR＝7.32，P＝0.002）。截断点分析显示，CHADS2与改良CHADS均≥1时对房颤消融预后的预测价值最高，对CHADS2评分≥1与改良CHADS评分≥1预测房颤消融预后的灵敏度、特异度、曲线下面积进行比较发现，差异均无统计学意义[分别为0.775 vs 0.800、0.358 vs 0.377、0.708（95%CI 0.601～0.806） vs 0.711（95%CI 0.605～0.818），均P＞0.05]。结论病史长短、左房内径、房颤类型、CHADS2评分≥1、CHADS2评分≥2、改良CHADS评分≥1、改良CHADS评分≥2均为心房颤动消融术后复发的独立危险因素，且改良CHADS评分与CHADS2评分对房颤消融预后具有同等的预测价值。展开更多
The Baibokoum syenitic pluton(BSP),located in southern Chad,to the NE of the Adamawa-Yadédomain,is one of the few strongly potassic magmatic bodies in the southern part of the Central African Fold Belt(CAFB)in Ch...The Baibokoum syenitic pluton(BSP),located in southern Chad,to the NE of the Adamawa-Yadédomain,is one of the few strongly potassic magmatic bodies in the southern part of the Central African Fold Belt(CAFB)in Chad.It has been previously studied petrologically,but its petrogenesis has remained poorly known.Petrographic and whole-rock geochemical data presented in this article highlight their magma genesis and geodynamic evolution.The BSP consists of medium-to coarse-grained syenites associated with minor microdiorites,which occur as syn-plutonic dikes and mafic microgranular enclaves(MME)coarse-and medium-grained syenites outcrop respectively to the core and the border of the BSP.The syenite displays high-K and alkaline to trans-alkaline affinity.Petrographic and geochemical data suggest that medium-to coarse-grained syenites are from single magma source that evolved and differentiated by fractional crystallization in a magma reservoir.REE profiles show enriched LREEs(La_(N)/Yb_(N)=6.19-45.55)while HREEs show an almost flat profile(Dy_(N)/Yb_(N)=1.0-2.23),and the La/Sm and Sm/Yb ratios have led to propose that the aforementioned rocks derived from the partial melting of a garnet-spinel-lherzolite mantle source.Negative Nb and Ta anomalies indicate that this mantle source was modified by the addition of subduction-related material.Th/Yb ratios associated with high Ba/La ratios indicate that enrichment of the source could be related to slab-derived fluids.The parental magma of the BSP was generated by partial melting of the metasomatized lithospheric mantle that was modified into arc-magmatism material in a subduction setting.Its emplacement took place in two successive stages:a static stage of fractional crystallization and crystal settling in a deep magma source and a dynamic stage in a shear deformation setting during which stratified magma rises towards the upper crust,with evolved syenite magma being emplaced first and diorite later.The emplacement of the BSP was probably controlled by the evolution of the Tcholliré-Banyo Fault and M'BéréShear Zone during the Pan-African orogeny.展开更多
Understanding water dynamics under the effect of climatic conditions is important to improve water sustainability over the medium-and long-term.Clay content can affect soil hydrothermal properties,and hence modify wat...Understanding water dynamics under the effect of climatic conditions is important to improve water sustainability over the medium-and long-term.Clay content can affect soil hydrothermal properties,and hence modify water and heat exchange between soil and atmosphere,e.g.evapotranspiration and infiltration.This work aims to develop a numerical approach to explore the influence of clay content on soil hydrothermal response to the timely climatic conditions in the Lake Chad region,Sahel Region of west-central Africa.The meteorological information at the studied points,i.e.points A and B with a clay content of 8.3%and 25%,during the year 2008 is collected from ERA5-Land hourly data.The numerical results allow for understanding the effect of clay content on the hydrothermal response of the surface soil layer.Specifically,the soil surface temperature under point A is lower than that under point B during the dry season due to the dominant effect of heat conduction.However,the converse tendency is observed during the wet season because of the combined effect of heat conduction and latent heat.The variations of soil volumetric water content are closely related to the timely interaction between the soil and atmosphere,in addition to the hydrothermal properties of soil.Moreover,the outcomes of this work improve the understanding of the heat and water dynamics under the effect of climatic conditions and clay content,and provide further insights into the potential water protection in arid and semi-arid regions in the future.展开更多
Based on two-dimensional/three-dimensional seismic and logging data,combined with the analysis of low-temperature thermochronology data,the unconformity surface characteristics and the patterns and dynamic mechanisms ...Based on two-dimensional/three-dimensional seismic and logging data,combined with the analysis of low-temperature thermochronology data,the unconformity surface characteristics and the patterns and dynamic mechanisms of inverted structures in the Doseo Basin in the Central and West African rift systems are systematically analyzed.Seismic profiles reveal two key inversion unconformable surfaces in the basin,i.e.the T_(5)interface within the Upper Cretaceous and the T_(4)interface at the top of the Cretaceous,which control the development of inverted structures in the basin.Four types of inverted structures,i.e.fault-associated,thrust,fold,and back-shaped negative flower,are identified.Spatially,they form six inverted structural belts trending in NE-NEE direction.The thermal history simulation of apatite fission track reveals two rapid cooling events in the late Late Cretaceous(85-80 Ma,cooling by 15℃)and the Eocene-Oligocene(30-40 Ma,cooling by 35℃),corresponding respectively to the formation periods of the T_(5)and T_(4)interface.The dynamics analysis of structural inversion indicates that the structural inversion in the Late Cretaceous was controlled by the subduction and long-range compression within the Tethys Ocean in the north of African Plate,while the structural inversion in the Eocene-Oligocene was drived by the stress transmission from the African-Eurasian collision.The two events were all controlled by the continuous tectonic regulation of the intracratonic basin by the evolution of the Tethys tectonic domain.The two periods of structural inversion enhanced the efficiency of oil and gas migration by controlling the types of traps(anticline and fault-related traps)and fault activation,precisely matching the hydrocarbon generation peaks of the Lower Cretaceous source rocks in the Late Cretaceous and Eocene,thereby controlling the formation of large-scale oil and gas reservoirs in the Doseo Basin.This geological insight provides a critical basis for the theoretical research on the evolution and hydrocarbon accumulation of inverted structures in discrete strike-slip rift systems.展开更多
目的：缺血性脑卒中是心脏手术后严重并发症，但其危险因素尚待进一步研究。本研究旨在探讨CHADS2评分对二尖瓣置换术围手术期脑卒中风险的预测作用。方法选择2005年1月至2014年12月解放军总医院心血管外科行二尖瓣置换且术前合并房颤...目的：缺血性脑卒中是心脏手术后严重并发症，但其危险因素尚待进一步研究。本研究旨在探讨CHADS2评分对二尖瓣置换术围手术期脑卒中风险的预测作用。方法选择2005年1月至2014年12月解放军总医院心血管外科行二尖瓣置换且术前合并房颤的患者共805例，年龄（53．7±10．5）岁，女性422例（52．4％）。观察不同CHADS2评分患者二尖瓣置换术后住院期间缺血性脑卒中发生情况；比较CHADS2评分≥2组和评分＜2组脑卒中发生率；采用多因素logistic回归分析方法对围手术期常见脑卒中危险因素进行分析，研究CHADS2评分与术后脑卒中的关系。结果全组患者CHADS2评分为0分者493例（61.2％），1分者185例（23.0％），2分者92例（11.4％），3分者26例（3.2％），4分者9例（1.1％）。术后住院期间发生缺血性脑卒中共14例，发生率为1.7％。住院期间死亡16例，死亡率2.0％。脑卒中发生于CHADS2评分为0分者6例（发生率1.2％），1分者2例（发生率1.1％），2分者3例（发生率3.3％），3分者2例（发生率7.7％），4分者1例（发生率11.1％）。与CHADS2评分＜2组比较， CHADS2评分≥2组脑卒中发生率显著升高（4.7％ vs 1.2％；P ＝0.005）。与低CHADS2评分组比较，高CHADS2评分组患者术前合并颈动脉狭窄、术中同期行CABG和植入机械瓣比例较高，术后机械通气时间更长（P＜0.05）。两组患者术后ICU停留时间以及住院期间病死率差异均无统计学意义（P＞0.05）。多因素logistic回归分析结果显示， CHADS2评分≥2（ OR ＝4.164，95％CI：1.388～12.495； P ＝0.011）和术后应用重组人凝血因子Ⅶa （OR＝11.757，95％CI：2.909～47.520；P＝0．001）是术后住院期间脑卒中的独立危险因素。结论 CHADS2评分高的房颤患者二尖瓣置换术后住院期间脑卒中发生率更高，CHADS2评分≥2是术后住院期间脑卒中的独立危险因素。 CHADS2评分对于预测房颤患者二尖瓣置换术围手术期脑卒中风险有一定价值，值得进一步研究。展开更多
文摘Located in Southeastern Chad. The Iro lake offers a great opportunity for the study of Precambrian formations and their Phanerozoic cover. Pluton is a Cal-alkaline granite. Due to its geographical location and geological features, it holds crucial information for understanding the evolution of the Saharan Meta craton (central Africa), which remains poorly studied. One of the objectives is to map the formations Precambrian age in Southeastern Chad. Based on the petrographic and geochemical results, we identified granitoids of pan-African age (biotite granite, aplite granite and pegmatite granite). This Precambrian basement is covered with sedimentary formations (clays, argillites, lateritic cuirasses, etc.). The mineral assemblage is characteristic of acid rocks. Geochemistry reveals rocks with a high SiO2 range (62% - 77%) giving sub-alkaline to calc-alkaline acid rocks with high k (4.62% to 6.39%). The granitoids are classified as S-type hyperaluminous granites. This classification is supported by the presence of peraluminous minerals (e.g., muscovite) within the Iro granitoids, which also have high (>1%). Geochemical variation within the granites is largely due to extensive crystal fractionation. The Pattern of REEs normalized to the primitive mantle shows a pronounced negative Eu anomaly, reflecting the crystallization process and fractional crystallization of plagioclase in the rock, and a positive Yb anomaly. The role of plagioclase fractionation was relatively major during the earlier intrusive stages (consistent with the presence of Eu anomalies) and slightly increased, together with biotite and K-feldspar fractionation, during the later (granitic) rock crystallization. The Pattern of the spider normalized to MORBs shows two pronounced negative anomalies in TiO2 and Cs and a slight negative anomaly in Ba. The loss of Ba, Ti and Cs may be caused by the plagioclase fractionation, apatite and ilmenite crystal. The Ba anomaly is also controlled by the presence of K-feldspar and mica. The observed Ti anomalies are due to the fractionation of magnetite indicating a subduction environment (or remelting of a source from a subduction environment).
文摘Two protected sites located on the outskirts of the Sena Oura National Park (PNSO) in West Mayo-Kebbi cover an area of 1800 m2 is pattern choose in pastoral enclave in both village. This study was undertaken to highlight the floristic diversity of the herbaceous and woody vegetation on these sites in the offing to know the ability of charge into UBT that most support the park peripheral. It took place on two experimental sites on a natural course in two villages: Wazetelan and Massang. The approach used for the study was a survey using the systematic sampling method and a 30 m × 30 m plot. The survey consisted in listing all the taxa in a floristically homogeneous plot, each assigned the Braun-Blanquet dominance abundance coefficient. These surveys revealed a floristic richness of 73 species, 58 genera, including 46 herbaceous and 26 woody species. The Shannon result gives H1' = 0.12 bit for herbaceous species and H2' = 0.44 bit for woody species, meaning that the herbaceous and woody populations of all the surveys have a very low species diversity, as H' < 3 according to the Shannon index assessment threshold. Herbaceous species are divided into 13 families and 33 genera. The most represented families are Fabaceae (27.3%) and Poaceae (21.9%). Most of the other families (1.3%) have only one species, if any. Herbaceous species are divided into 33 genera grouped into 13 families. The most represented families are Fabaces (16 species), 34%, and Poaceae (12 species), 26%. The 26 woody species, most of which come from itinerant surveys, are distributed across 24 genera and 12 families, the most important of which is Fabaceae with 09 species (34.6%). This floristic assessment, in terms of quantity and quality, has enabled us to estimate the carrying capacity of the two pastoral enclaves in Dari and Goumadji cantons, and to guide the government’s actions with regard to rangeland management.
文摘A total of fifty (50) samples of water from Lake Fitri (Chad), with 25 samples per island (Domoro and Maguite). The aim of this study was to analyze the bacteriological, biochemical and physico-chemical quality of the water in Lake Fitri in Chad. Standard microbiology methods were used. Isolated strains of enterobacteria were characterized by API 20E and API Staph galleries and confirmed by API Web. Antibiotic resistance was performed according to the recommendations of the antibiogram committee (CA-SFM, 2019). Physico-chemical analysis of the water was carried out by (Rodier, 2009). The microbiological results revealed an abundance on the Domoro islands (5.37.106 ± 1.5.105 and 1.97.105 ± 4.94.104), successively for total aerobic mesophilic flora (FMAT), and thermotolerant coliform (E. coli) and on the Maguite Islands (4.71.106 ± 7.14.105 and 2.32.105 ± 2.86.104), alternately for total aerobic mesophilic flora (FMAT), and thermotolerant coliform (E. coli). The results obtained after incubation of the biochemical tests using the API 20E and API Staph galleries and their proposed numerical profile analyzed using Api software and confirmed by Api Web confirmed the contamination of the waters of Lake Fitri by pathogenic strains of E. coli, Staphylococcus and Salmonella spp. The results of the antibiogram carried out show the emergence of certain resistances to Tobramycin, Flucytosine and Teicoplanin. The average levels of BOD5, COD, SS, Nitrate (NO3) and Nitrite (NO2) for Domoro Island were 32.14 ± 2.37 mg/L, 423.86 ± 4.78 mg/L, 65.42 ± 2.27 mg/L, 0.04 ± 0.01 mg/L and 3.32 ± 1.48 mg/L respectively. The water from the islands of Lake Fitri must therefore be rigorously treated before consumption.
文摘This study focuses on the thermophysical characterizations of composite materials made from polypropylene reinforced with residues and fibers from Borassus wood from Chad. These properties are experimentally determined at different temperatures using the hot wire method of the “FP2C” machine, where the hot wire probe is inserted between two specimens. The values of the thermal conductivity in powdered Borassus wood range from 0.170 W/mK to 0.182 W/mK for female wood (FNTF) and from 0.169 W/mK to 0.173 W/mK for male wood. For the female and male fibers, the thermal conductivity values range from 0.137 W/mK to 0.157 W/mK for the female and from 0.138 W/mK to 0.168 W/mK for the male. The thermal effusivity of the residues and fibers of Borassus wood varies from: 509.6 Ws1/2/m2K to 543 Ws1/2/m2K for the powder of female wood and from 524.6 Ws1/2/m2K to 547 Ws1/2/m2K for the powder of male wood. For the fibers of Borassus wood, the values range from 410.6 Ws1/2/m2K to 523.6 Ws1/2/m2K for the female wood fibers and from 420.3 Ws1/2/m2K to 480.3 Ws1/2/m2K for the male wood fibers. These results are important for the applications of Borassus wood residues and fibers in construction works regarding the thermal insulation of habitats.
文摘Background: Social determinants of health (SDOH) significantly influence diseases with environmental components, like vector-borne parasitic diseases. This study aims to examine how these factors influence vector-borne parasitic diseases (VBPDs) transmission in Chad and provide recommendations for policy improvements. Methods: The study adopts the WHO Conceptual Framework of SDOH to compare two regions in Southern Chad: Kouh-Est, which has an ongoing vector control program, and Grand-Sido, which lacks such a program. The study includes both nomadic and sedentary populations to provide a comprehensive understanding of the SDOH influencing VBPDs. Households were randomly selected. Data on sociodemographic characteristics, literacy, knowledge of VBPDs and protective measures, and access to education and health facilities were collected. Results: A total of 202 households from 17 villages, including 820 participants, were surveyed. Agriculture, livestock, and fishing were the main occupations, involving 84.1% of participants. Literacy was low, with 36.7% non-educated, 47.7% completing primary school, 14.5% secondary school, and only 0.3% reaching tertiary education. Most villages lacked schools beyond the primary level, and nomadic populations were significantly less educated than sedentary ones (p Conclusion: Educational deficiencies, lack of protective measures against vectors, inadequate healthcare resources, and lifestyle conditions aggravated by poor road infrastructure, limited transportation, and economic constraints contribute to worsened VBPDs outcomes in these rural populations. Addressing these systemic issues in the surveyed communities is essential for improving health equity and VBPDs outcomes in these regions specifically and in similar populations settings more broadly.
文摘目的：探讨心力衰竭高血压、年龄、糖尿病和脑卒中（包括一过性脑缺血）（CHADS2）评分及改良CHADS评分对心房颤动（房颤）射频消融术后复发的预测价值。方法对2010年7月至2012年3月在我院行射频消融术的93例房颤患者追踪随访12个月，术后1，3，6，9，12个月行12导联心电图或长程心电图检查，结合临床症状及心电图检查结果将其分为复发组（n＝40）和未复发组（n＝53），采用单因素和多因素分析消融术后房颤复发的危险因素。结果93例房颤患者中持续性房颤35例（37.63%），随访12个月时复发40例（43.01%）。房颤复发组与未复发组在平均年龄（P＜0.01）、年龄＞70岁（P＜0.05）、病史（P＜0.05）、房颤类型（P＜0.01）、左房内径（P＜0.001）、左室射血分数（P＜0.05）、血细胞比容（P＜0.05）、是否伴心力衰竭（P＜0.05）、是否伴高血压（P＜0.01）、是否伴糖尿病（P＜0.05）、是否有一过性脑缺血或脑卒中史（P＜0.05）、术后是否服用血管紧张素转换酶抑制剂和血管紧张素Ⅱ受体拮抗剂（ACEI/ARB，P＜0.01）、术后是否服用Ⅲ类抗心律失常药（P＜0.05）、CHADS2评分≥1（P＜0.001）等方面差异有统计学意义。logistic回归分析发现，病史、房颤类型、左房内径、CHADS2评分≥1为房颤术后复发的独立危险因素（病史长短：OR＝1.16，P＝0.020；左房内径：OR＝1.17，P＝0.025；房颤类型：OR＝3.34，P＝0.050；CHADS2评分≥1：OR＝5.93，P＝0.019）。进一步分析发现，CHADS2评分≥2、改良CHADS评分≥1、改良CHADS评分≥2亦为房颤术后复发的独立危险因素（CHADS2≥2：OR＝5.42，P＝0.028；改良CHADS评分≥1：OR＝6.64，P＝0.015；改良CHADS评分≥2：OR＝7.32，P＝0.002）。截断点分析显示，CHADS2与改良CHADS均≥1时对房颤消融预后的预测价值最高，对CHADS2评分≥1与改良CHADS评分≥1预测房颤消融预后的灵敏度、特异度、曲线下面积进行比较发现，差异均无统计学意义[分别为0.775 vs 0.800、0.358 vs 0.377、0.708（95%CI 0.601～0.806） vs 0.711（95%CI 0.605～0.818），均P＞0.05]。结论病史长短、左房内径、房颤类型、CHADS2评分≥1、CHADS2评分≥2、改良CHADS评分≥1、改良CHADS评分≥2均为心房颤动消融术后复发的独立危险因素，且改良CHADS评分与CHADS2评分对房颤消融预后具有同等的预测价值。
文摘The Baibokoum syenitic pluton(BSP),located in southern Chad,to the NE of the Adamawa-Yadédomain,is one of the few strongly potassic magmatic bodies in the southern part of the Central African Fold Belt(CAFB)in Chad.It has been previously studied petrologically,but its petrogenesis has remained poorly known.Petrographic and whole-rock geochemical data presented in this article highlight their magma genesis and geodynamic evolution.The BSP consists of medium-to coarse-grained syenites associated with minor microdiorites,which occur as syn-plutonic dikes and mafic microgranular enclaves(MME)coarse-and medium-grained syenites outcrop respectively to the core and the border of the BSP.The syenite displays high-K and alkaline to trans-alkaline affinity.Petrographic and geochemical data suggest that medium-to coarse-grained syenites are from single magma source that evolved and differentiated by fractional crystallization in a magma reservoir.REE profiles show enriched LREEs(La_(N)/Yb_(N)=6.19-45.55)while HREEs show an almost flat profile(Dy_(N)/Yb_(N)=1.0-2.23),and the La/Sm and Sm/Yb ratios have led to propose that the aforementioned rocks derived from the partial melting of a garnet-spinel-lherzolite mantle source.Negative Nb and Ta anomalies indicate that this mantle source was modified by the addition of subduction-related material.Th/Yb ratios associated with high Ba/La ratios indicate that enrichment of the source could be related to slab-derived fluids.The parental magma of the BSP was generated by partial melting of the metasomatized lithospheric mantle that was modified into arc-magmatism material in a subduction setting.Its emplacement took place in two successive stages:a static stage of fractional crystallization and crystal settling in a deep magma source and a dynamic stage in a shear deformation setting during which stratified magma rises towards the upper crust,with evolved syenite magma being emplaced first and diorite later.The emplacement of the BSP was probably controlled by the evolution of the Tcholliré-Banyo Fault and M'BéréShear Zone during the Pan-African orogeny.
基金the National Natural Science Foundation of China(Grant No.42207171).
文摘Understanding water dynamics under the effect of climatic conditions is important to improve water sustainability over the medium-and long-term.Clay content can affect soil hydrothermal properties,and hence modify water and heat exchange between soil and atmosphere,e.g.evapotranspiration and infiltration.This work aims to develop a numerical approach to explore the influence of clay content on soil hydrothermal response to the timely climatic conditions in the Lake Chad region,Sahel Region of west-central Africa.The meteorological information at the studied points,i.e.points A and B with a clay content of 8.3%and 25%,during the year 2008 is collected from ERA5-Land hourly data.The numerical results allow for understanding the effect of clay content on the hydrothermal response of the surface soil layer.Specifically,the soil surface temperature under point A is lower than that under point B during the dry season due to the dominant effect of heat conduction.However,the converse tendency is observed during the wet season because of the combined effect of heat conduction and latent heat.The variations of soil volumetric water content are closely related to the timely interaction between the soil and atmosphere,in addition to the hydrothermal properties of soil.Moreover,the outcomes of this work improve the understanding of the heat and water dynamics under the effect of climatic conditions and clay content,and provide further insights into the potential water protection in arid and semi-arid regions in the future.
基金Supported by the National Natural Science Foundation of China(92255302)Science and Technology Project of PetroChina Company Limited(2023ZZ07).
文摘Based on two-dimensional/three-dimensional seismic and logging data,combined with the analysis of low-temperature thermochronology data,the unconformity surface characteristics and the patterns and dynamic mechanisms of inverted structures in the Doseo Basin in the Central and West African rift systems are systematically analyzed.Seismic profiles reveal two key inversion unconformable surfaces in the basin,i.e.the T_(5)interface within the Upper Cretaceous and the T_(4)interface at the top of the Cretaceous,which control the development of inverted structures in the basin.Four types of inverted structures,i.e.fault-associated,thrust,fold,and back-shaped negative flower,are identified.Spatially,they form six inverted structural belts trending in NE-NEE direction.The thermal history simulation of apatite fission track reveals two rapid cooling events in the late Late Cretaceous(85-80 Ma,cooling by 15℃)and the Eocene-Oligocene(30-40 Ma,cooling by 35℃),corresponding respectively to the formation periods of the T_(5)and T_(4)interface.The dynamics analysis of structural inversion indicates that the structural inversion in the Late Cretaceous was controlled by the subduction and long-range compression within the Tethys Ocean in the north of African Plate,while the structural inversion in the Eocene-Oligocene was drived by the stress transmission from the African-Eurasian collision.The two events were all controlled by the continuous tectonic regulation of the intracratonic basin by the evolution of the Tethys tectonic domain.The two periods of structural inversion enhanced the efficiency of oil and gas migration by controlling the types of traps(anticline and fault-related traps)and fault activation,precisely matching the hydrocarbon generation peaks of the Lower Cretaceous source rocks in the Late Cretaceous and Eocene,thereby controlling the formation of large-scale oil and gas reservoirs in the Doseo Basin.This geological insight provides a critical basis for the theoretical research on the evolution and hydrocarbon accumulation of inverted structures in discrete strike-slip rift systems.
文摘目的：缺血性脑卒中是心脏手术后严重并发症，但其危险因素尚待进一步研究。本研究旨在探讨CHADS2评分对二尖瓣置换术围手术期脑卒中风险的预测作用。方法选择2005年1月至2014年12月解放军总医院心血管外科行二尖瓣置换且术前合并房颤的患者共805例，年龄（53．7±10．5）岁，女性422例（52．4％）。观察不同CHADS2评分患者二尖瓣置换术后住院期间缺血性脑卒中发生情况；比较CHADS2评分≥2组和评分＜2组脑卒中发生率；采用多因素logistic回归分析方法对围手术期常见脑卒中危险因素进行分析，研究CHADS2评分与术后脑卒中的关系。结果全组患者CHADS2评分为0分者493例（61.2％），1分者185例（23.0％），2分者92例（11.4％），3分者26例（3.2％），4分者9例（1.1％）。术后住院期间发生缺血性脑卒中共14例，发生率为1.7％。住院期间死亡16例，死亡率2.0％。脑卒中发生于CHADS2评分为0分者6例（发生率1.2％），1分者2例（发生率1.1％），2分者3例（发生率3.3％），3分者2例（发生率7.7％），4分者1例（发生率11.1％）。与CHADS2评分＜2组比较， CHADS2评分≥2组脑卒中发生率显著升高（4.7％ vs 1.2％；P ＝0.005）。与低CHADS2评分组比较，高CHADS2评分组患者术前合并颈动脉狭窄、术中同期行CABG和植入机械瓣比例较高，术后机械通气时间更长（P＜0.05）。两组患者术后ICU停留时间以及住院期间病死率差异均无统计学意义（P＞0.05）。多因素logistic回归分析结果显示， CHADS2评分≥2（ OR ＝4.164，95％CI：1.388～12.495； P ＝0.011）和术后应用重组人凝血因子Ⅶa （OR＝11.757，95％CI：2.909～47.520；P＝0．001）是术后住院期间脑卒中的独立危险因素。结论 CHADS2评分高的房颤患者二尖瓣置换术后住院期间脑卒中发生率更高，CHADS2评分≥2是术后住院期间脑卒中的独立危险因素。 CHADS2评分对于预测房颤患者二尖瓣置换术围手术期脑卒中风险有一定价值，值得进一步研究。
