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Risk Factors for Neonatal Mortality at the Institute of Nutrition and Child Health of the Donka/Guinea-Conakry National Hospital

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Open Journal of Pediatrics 2024年第2期14卷 327-337页

作者： Bangoura Mmah Aminata Kolié Ouo Ouo Camara Salématou Hassimiou Baldé Mariama Bangoura Kaba Diop Mamadou Moustapha Camara Emmanuel Diallo Fatoumata Binta Doukouré Mamadou Aliou Mamadou Mouctar Sow Bémy Pé Néabey Institut de Nutrition et de Santé de l’Enfant Conakry Guinea Service de Pédiatrie Hô pital National Donka Conakry Guinea Service de Pédiatrie Hô pital National d’Ignace Deen Conakry Guinea

Introduction: The birth of a baby is a moment of joy and celebration. However, the neonatal period is a very delicate phase of life. Neonatal mortality rates remain high in low-income countries. In Guinea, after 20 years, this rate has fallen from 34.2% in 1998 to 32% in 2018. Objective: To identify the main risk factors for neonatal mortality. Methods: This was an observational, analytical case-control study, lasting 6 months from January 1 to June 30, 2019, conducted at the Institut de Nutrition et de la Santé de l’Enfant (inse) at Donka National Hospital. Results: We collected 242 cases and 242 controls, i.e. a total of 484 records. 748 patients were registered, with 32.35% deaths. 82.86% of deaths occurred in the early neonatal period. Statistical analysis revealed the main risk factors: prematurity (RQ 7.39 95% CI 3.27 - 16.61 p = 0.0000003), hypothermia (RQ 2.29 95% CI 1.51 - 3.46 p = 0.0001), acute fetal distress (RQ 2.13 95% CI 1.33 - 3.43 p = 0.0016), low birth weight (QR 1.91 95% CI 1.12 - 3.24 p = 0.016), home birth (QR 3.26 95% CI 1.25 - 8.46 p = 0.015). Conclusion: Neonatal mortality is a health problem in the inse neonatology department. To reduce the mortality rate in this referral facility, it is essential to equip it and provide ongoing training for staff.

关键词： Neonatal Mortality inse Guinea-Conakry

Remarkable plasticity and softness of polymorphic inse van der Waals crystals

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Journal of Materiomics 2023年第4期9卷 709-716页

作者： Yupeng Ma Haoran Huang Yifei Liu Heyang Chen Xudong Bai Kunpeng Zhao Min Jin Tian-Ran Wei Xun Shi State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China Wuzhen Laboratory Tongxiang314500China College of Materials Shanghai Dianji UniversityShanghai 201306China State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China

Indium selenide(inse)crystals are reported to show exceptional plasticity,a new property to twodimensional van der Waals(2D vdW)semiconductors.However,the correlation between plasticity and specific prototypes is unclear,and the understanding of detailed plastic deformation mechanisms is inadequate.Here three prototypes of inse are predicted to be plastically deformable by calculation,and the plasticity of polymorphic crystals is verified by experiment.Moreover,distinct nanoindentation behaviors are seen on the cleavage and cross-section surfaces.The modulus and hardness of inse are the lowest ones among a large variety of materials.The plastic deformation is further perceived from chemical interactions during the slip process.Particularly for the cross-layer slip,the initial In-Se bonds break while new In-In and Se-Se bonds are newly formed,maintaining a decent interaction strength.The remarkable plasticity and softness alongside the novel physical properties,endow inse great promise for application in deformable and flexible electronics.

关键词： inse 2D vdW crystal Polymorphism Plasticity Softness

Liquid phase exfoliation of indium selenide:Achieving the optimum exfoliating parameters and unraveling the mechanism

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Progress in Natural Science:Materials International 2022年第6期32卷 700-704页

作者： Huihui Li Bowen Liu Xingchen Yang Yang Gao Xinying Luo Xin Guan Zhen Zhang Zhongliang Yu Bin Wang Key Laboratory of Molecular Optoelectronic Sciences School of Science Tianjin University CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology (NCNST) University of Chinese Academy of Sciences State Key Laboratory of Organic–Inorganic Composites College of Chemical Engineering College of Materials Science and Engineering Beijing University of Chemical Technology Department of Environmental Science and Engineering University of Science and Technology Beijing Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants

The two-dimensional(2D) van der Waals indium selenide(inse) exhibits the ultra-low intralayer Young’s modulus yet the high interlayer cleavage and slipping energy,which could thus be obtained by the liquid phase exfoliation(LPE) method.Here,we designed 48 experiments to systematically achieve its optimum LPE parameters including the exfoliating solvent of N-Methyl-2-pyrrolidinone(NMP),ultrasonic power of 180 W,ultrasonic time of 12 h and exfoliating concentration of 6.25 mg/mL.The resulting optimal 2D inse nanosheets show a uniform lateral size distribution of about 200 nm without impurities.We further analyzed the underlying exfoliating mechanism through the scanning electron microscopy(SEM) investigations.The results show that NMP has the more suitable Hansen solubility parameters to disperse and stabilize the 2D nanosheets.Increasing the ultrasonic power and time can provide plenty of energy to destroy the van der waals’ force that exist between the interlayers of inse and induce intralayer fragmentation.This work would provide a significant guideline for selecting exfoliating parameters to obtain the expected inse nanosheets and thus extend its applications in optical sensors and nanocomposites.

关键词： inse Liquid phase exfoliating Parameters Optimization Exfoliating mechanism

Te掺杂对二维inse抗氧化性以及电子结构的影响

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物理学报 2023年第12期72卷 83-92页

作者：苗瑞霞谢妙春程开李田甜杨小峰王业飞张德栋西安邮电大学电子工程学院西安710121

In Se作为一种典型的二维层状半导体材料,具有优异的电学性能以及适中可调的带隙,在光电器件中表现出诱人的应用前景.然而有研究表明,单硒空位(Vse)体系的In Se易受O_(2)分子影响,造成In Se材料降解,严重影响其在电子器件领域的应用.本... 详细信息

In Se作为一种典型的二维层状半导体材料,具有优异的电学性能以及适中可调的带隙,在光电器件中表现出诱人的应用前景.然而有研究表明,单硒空位(Vse)体系的In Se易受O_(2)分子影响,造成In Se材料降解,严重影响其在电子器件领域的应用.本文基于In Se降解机理,提出了碲(Te)替位掺杂的方法,用于提升该材料的环境稳定性.利用密度泛函理论对不同体系电子结构、吸附能、能量反应路径等进行分析,发现Te掺杂不仅显著改善缺陷引起的In Se降解问题,同时可消除Vse产生的缺陷态,起到缺陷补偿作用.具体研究结果如下:1)O_(2)分子在Te掺杂In Se表面(In Se-Te)的解离能垒高达2.67 e V,说明其具有较强的抗氧化能力;2)O_(2)分子在In Se-Te表面保持3.87A的距离,吸附能仅有-0.03 e V,表明O_(2)分子物理吸附在其单层表面;3)Te掺杂不仅提升材料抗氧化能力,同时还消除了Vse产生的缺陷态.该研究结果将有助于进一步提升In Se二维材料器件的环境稳定性,推动In Se二维器件研究和发展.

关键词： inse 抗氧化性掺杂电子结构

通过Ag阵列耦合增强少层inse的光学响应

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Science China Materials 2023年第7期66卷 2788-2794页

作者：孙荣欢刘勇陈荧蒋琪陈平安帅钦骆子煜杨鑫蒋英胡袁源陈舒拉潘安练 Department of Key Laboratory for Micro-Nano Physics and Technology of Hunan Province State Key Laboratory of Chemo/Biosensing and ChemometricsCollege of Materials Science and EngineeringHunan UniversityChangsha 410082China Department of School of Physics and Electronics Hunan UniversityChangsha 410082China

具有高发光性能的二维材料被认为是实现光电器件应用的极具前途的材料.其中,硒化铟(inse)是一种具有代表性的二维材料,近些年在光电领域表现出巨大的应用潜力,因此吸引了研究者们的广泛关注.然而,inse的光-物质相互作用极其微弱,因为其... 详细信息

具有高发光性能的二维材料被认为是实现光电器件应用的极具前途的材料.其中,硒化铟(inse)是一种具有代表性的二维材料,近些年在光电领域表现出巨大的应用潜力,因此吸引了研究者们的广泛关注.然而,inse的光-物质相互作用极其微弱,因为其带隙激子的偏振取向是面外的,主要被面外偏振光激发而对正常入射光(面内偏振)的响应极其微弱,这大大限制了其在光电器件中的实际应用.在此,我们提出了一种方法,即通过将少层inse转移到Ag纳米棱镜阵列上,显著提升inse在线性和非线性体系的光学响应.结合实验分析,增强的机理主要来自于两种机制的协同作用:一方面,局域表面等离子体共振产生的局部强化电磁场垂直分布于金属表面,与面外偏振的inse带隙激子发生高效耦合,增强了inse的光-物质相互作用;另一方面,独特设计的弯曲结构增加了入射光在平面外的偏振分量,促使inse面外激子对光的吸收和散射效率增强.通过进一步调整inse的厚度,我们实现了光致发光和二次谐波信号的两个数量级的增强.因此,我们的工作为改善inse的光学特性提供了一个有效的途径,使其在光电器件的实际应用中迈出了重要的一步.

关键词： inse Ag prism array localized surface plasmon resonance optical response modulation photoluminescence SHG intensity enhanced

inse/hBN/graphite heterostructure for high-performance 2D electronics and flexible electronics

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Nano Research 2020年第4期13卷 1127-1132页

作者： Liangmei Wu Jinan Shi Zhang Zhou Jiahao Yan Aiwei Wang Ce Bian Jiajun Ma Ruisong Ma Hongtao Liu Jiancui Chen Yuan Huang Wu Zhou Lihong Bao Min Ouyang Sokrates T.Pantelides Hong-Jun Gao Institute of Physics Chinese Academy of SciencesP.O.Box 603y Beijing 100190China University of Chinese Academy of Sciences&CAS Center for Excellence in Topological Quantum Computation Chinese Academy of SciencesPO Box 603Beijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China Department of Physics University of MarylandMD 20742USA Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science Vanderbilt UniversityNashvilleTennessee 37235USA

Two-dimensional(2D)materials as channel materials provide a promising alternative route for future electronics and flexible electronics,but the device performance is affected by the quality of interface between the 2D-material channel and the gate dielectric.Here we demonstrate an indium selenide(lnSe)/hexagonal boron nitride(hBN)/graphite heterostructure as a 2D field-effect transistor(FET),with inse as channel material,hBN as dielectric,and graphite as gate.The fabricated FETs feature high electron mobility up to 1,146 cm2·V^-1·s^-1 at room temperature and on/off ratio up to 1010 due to the atomically flat gate dielectric.Integrated digital inverters based on inse/hBN/graphite heterostructures are constructed by local gating modulation and an ultrahigh voltage gain up to 93.4 is obtained.Taking advantages of the mechanical flexibility of these materials,we integrated the heterostructured inse FET on a flexible substrate,exhibiting little modification of device performance at a high strain level of up to 2%.Such high-performance heterostructured device configuration based on 2D materials provides a new way for future electronics and flexible electronics.

关键词： inse van der Waals heterostruture 2D electronics flexible electronics

Scaling law of hydrogen evolution reaction for inse monolayer with 3d transition metals doping and strain engineering

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Journal of Energy Chemistry 2020年第2期29卷 107-114页

作者： Chao Wang Yanyu Liu Jian Yuan Ping Wu Wei Zhou Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology Faculty of ScienceDepartment of Applied PhysicsInstitute of Advanced Materials PhysicsTianjin UniversityTianjin 300072China School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China

Recently, two dimensional In Se attracts great attentions as potential hydrogen production photocatalysts.Here, comprehensive investigations on the hydrogen evolution reaction activity of In Se monolayer with3 d transition metal doping and biaxial strain were performed based on the density functional theory.Transition metal dopants significantly increase the bonding strength between H and Se, and then adjust the hydrogen adsorption free energy to 0.02 e V by Zn doping. The enhanced hydrogen evolution reaction activity results from less electron occupying H 1 s-Se 4 pzanti-bonding states, which is well correlated with the pzband center level. Importantly, the universal scalling law was proposed to descript the evolution of hydrogen adsorption free energy including both doping and strain effects. Moreover, with appropriate band alignment, optical absorption, and carriers separation ability, Zn doped In Se monolayer is considered as a promising candidate of visible-light photocatalyst for hydrogen production.

关键词： inse monolayer Visible light photocatalyst Strain engineering 3d transition metals doping Hydrogen evolution reaction

Optical emission enhancement of bent inse thin films

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Science China(Information Sciences) 2021年第4期64卷 149-156页

作者： Jiahao XIE Lijun ZHANG State Key Laboratory of Integrated Optoelectronics Key Laboratory of Automobile Materials of MOESchool of Materials Science and Engineering Jilin University

In contrast to the majority of two-dimensional semiconductors such as transition metal dichalcogenides, indium selenide(inse) possesses an intrinsic large out-of-plane oriented band-edge luminescent dipole. This unique anisotropic feature of band-edge optical emissions can be exploited to achieve enhanced optical signal in bent regions of materials created by geometrical modification. We herein investigate based on first-principle calculations the mechanism of this optical emission enhancement by modelling the photoluminescence processes in bent and flat regions of the inse thin film. We propose in our model that the shorter-wavelength interband transition, labelled as transition B′, between the second-highest valence band and the bottom of conduction band plays an important role in the enhancing process. Our model robustly describes the dependence of optical emission enhancement in the bent inse thin films on thickness, incident light orientation, and excitation photon energy. In particular, we found that when excitation photon energy is lower than the energy of transition B′, strong enhancement up to hundreds of times can be obtained by applying an incident light at an angle less than 70° to the inse layers. Our results provide useful references for modulating luminescent properties of inse films toward flexible optoelectronic device applications.

关键词： inse enhanced luminescence 2D semiconductor optical transition optical anisotropy

Electrostatic gating of solid-ion-conductor on inse flakes and inse/h-BN heterostructures

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Chinese Physics B 2020年第11期29卷 543-547页

作者：周璋吴良妹陈建翠马佳俊黄元申承民鲍丽宏高鸿钧 Institute of Physics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences&CAS Center for Excellence in Topological Quantum Computation Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China

We report the electrical transport properties of inse flakes electrostatically gated by a solid ion conductor.The large tuning capability of the solid ion conductor as gating dielectric is confirmed by the saturation gate voltage as low as^1 V and steep subthreshold swing(83 mV/dec).The p-type conduction behavior of inse is obtained when negative gate voltages are biased.Chemical doping of the solid ion conductor is suppressed by inserting a buffer layer of hexagonal boron nitride(h-BN)between inse and the solid-ion-conductor substrate.By comparing the performance of devices with and without h-BN,the capacitance of solid ion conductors is extracted to be the same as that of^2 nm h-BN,and the mobility of inse on solid ion conductors is comparable to that on the SiO2 substrate.Our results show that solid ion conductors provide a facile and powerful method for electrostatic doping.

关键词： solid ion conductors electrostatic gating inse van der Waals heterostructure