目的观察气管导管(endotracheal tube,ETT)表面细菌定植及生物膜(biofilm,BF)形成,探讨其与机械通气新生儿伴发下呼吸道感染之间的相关性。方法以我院2005年1至6月,经治的20例机械通气新生儿为研究对象,观察机械通气过程中下呼吸道感染...目的观察气管导管(endotracheal tube,ETT)表面细菌定植及生物膜(biofilm,BF)形成,探讨其与机械通气新生儿伴发下呼吸道感染之间的相关性。方法以我院2005年1至6月,经治的20例机械通气新生儿为研究对象,观察机械通气过程中下呼吸道感染发生情况,收集第一次拔除或更换的 ETT,扫描电镜(Scanning Electron Microscopy,SEM)观察 ETT 表面 BF(ETT-BF)形成情况及结构,并对 ETT 表面和下呼吸道分泌物进行细菌分离、鉴定和药敏分析。结果①20例中13例机械通气前并不存在下呼吸道感染,在机械通气过程伴发了下呼吸道感染,并在整个机械通气期间持续存在;其中有9例 ETT 留置时间与机械通气时间一致(平均机械通气时间为3.6 d)。②SEM 观察发现留置时间超过1 d 的 ETT 表面细菌定植增加(12/20),3 d 左右细菌在 ETT 表面初步形成 BF,超过3 d 表面 BF 结构更加成熟复杂。③ETT 表面培养阳性14例(包括正常菌群4例),分离得到病原菌7种;下呼吸道分泌物培养阳性13例(包括正常菌群1例),分离得到病原菌10种;其中7例 ETT表面和下呼吸道分泌物同时分离得到同种菌种,其 ETT 留置时间为(3.2±1)d,占 ETT 培养阳性的50%。④ETT 表面和下呼吸道分泌物分离得到的 G^-细菌均对抗生素多重耐药。结论 ETT 表面细菌定植及 BF 形成与长时间机械通气新生儿伴发下呼吸道感染之间可能存在一定相关性,ETT-BF 可能是其感染持续存在的一个病原来源。展开更多
How do you get information from an article as much and fast as possible while you are reading? It is a very important thing for us——Chinese readers. Reading is an important element in our English study. Mastering re...How do you get information from an article as much and fast as possible while you are reading? It is a very important thing for us——Chinese readers. Reading is an important element in our English study. Mastering reading skills will help increase our reading speed and comprehend what we read. Now several reading skills are to be discussed in this paper.展开更多
Exploring high-efficient catalysts for hydrogen evolution reaction(HER)has become very urgeht for resolving the energy related issues.Recently,two-dimensional layered MoS2 and its heterostructures with graphene or oth...Exploring high-efficient catalysts for hydrogen evolution reaction(HER)has become very urgeht for resolving the energy related issues.Recently,two-dimensional layered MoS2 and its heterostructures with graphene or other traditional photocatalysts have presented great potentials for electrocatalytic and photocatalytic HER applications.On-site investigations of the atomic-scale structures and local electronic properties of the catalytically active sites are the key points for understanding the internal mechanisms,which however are hard to be achievec from the practical systems.Hereby,this review focuses on the recent progresses on the on-site scanning tunneling microscopy/spectroscopy investigations of the atomic structures and electronic properties of the ultrahigh-vacuum deposited and chemical vapor deposition(CVD)synthesized monolayer MoS2 and MoSz/graphene vertical stacks on the electrodes of Au(111)and Au foils.The correlations between the respective HER activities,edge types and edge electronic states are comparatively introduced.Secondly,this review also introduces thephotocatalytic HER applications of CVD-grown MoS2/WS2 and WS/MoS2 vertical stacks on Au foils,mainly considering of their type-ll band.alignments and the novel interlayer charge transfer behaviors.Finally,future research directions are also proposed for in-depth understanding of the catalytic mechanism,as well as for exploring more efficient HER catalysts.展开更多
Vertical heterostructures based on two-dimensional(2D)materials have attracted widespread interest for their numerous applications in electronic and optoelectronic devices.Herein,we report the direct construct!on of a...Vertical heterostructures based on two-dimensional(2D)materials have attracted widespread interest for their numerous applications in electronic and optoelectronic devices.Herein,we report the direct construct!on of an abnormal graphene/ReSe2 stack on Au foils by a two-step chemical vapor deposition(CVD)strategy.During the second growth stage,mono layer ReSe2 is found to prefere ntially evolve at the irUerface between the first-grown graphene layer and the Au substrate.The unusual stacking behavior is unraveled by in-situ"cutting open"the upper graphene from the defects to expose the lower ReSe2 using scanning tunneling microscopy(STM).From combination of these results with density functional theory calculations,the domain boundaries and edge sites of graphene are proposed to be adsorption sites for Re and Se precursors,further facilitating the growth of ReSe2 at the van der Waals gap of graphene/Au.This work hereby offers an intriguing strategy for obtaining vertical 2D heterostructures featured with an ultra-clean interface and a designed stacking geometry.展开更多
Graphene-h-BN hybrid nanostructures are grown in one step on the Pt(111) surface by ultra-high vacuum chemical vapor deposition using a single precursor,the dimethylamino borane complex.By varying the deposition condi...Graphene-h-BN hybrid nanostructures are grown in one step on the Pt(111) surface by ultra-high vacuum chemical vapor deposition using a single precursor,the dimethylamino borane complex.By varying the deposition conditions,different nanostructures ranging from a fully continuous hybrid monolayer to well-separated Janus nanodots can be obtained.The growth starts with heterogeneous nucleation on morphological defects such as Pt step edges and proceeds by the addition of small clusters formed by the decomposition of the dimethylamino borane complex.Scanning tunneling microscopy measurements indicate that a sharp zigzag in-plane boundary is formed when graphene grows aligned with the Pt substrate and consequently with the h-BN layer as well.When graphene is rotated by 30°,the graphene armchair edges are seamlessly connected to h-BN zigzag edges.This is confirmed by a thorough density functional theory (DFT) study.Angle resolved photoemission spectroscopy (ARPES) data suggests that both h-BN and graphene present the typical electronic structure of self-standing non-interacting materials.展开更多
Ultrathin ZnO nano structures prese nt in teresti ng two-dimensi on al(2D)graphene-like structure in contrast to wurtzite structure in bulk ZnO.Growth on Au(111)has been regarded as a well-established route to the 2D ...Ultrathin ZnO nano structures prese nt in teresti ng two-dimensi on al(2D)graphene-like structure in contrast to wurtzite structure in bulk ZnO.Growth on Au(111)has been regarded as a well-established route to the 2D ZnO layers while controlled growth of uniform ZnO nano structures remains as a challe nge.Here,reactive deposition of Zn in O3 and NO2 was employed,which is investigated by sea nning tunneling microscopy and X-ray photoelectr on spectroscopy(XPS).We dem on strate that uniform ZnO mono layer nanoislands and films can be obtained on Au(111)using O3 and uniform ZnO bilayer nanoislands and films form on Au(111)using NO2,respectively.Formation of atomic oxyge n overlayers on Au(111)via exposure to O3 is critical to the formatio n of uniform ZnO mono layer nano structures atop.Near ambient pressure XPS studies revealed that n early full hydroxy lati on occurs on mono layer ZnO structures upon exposure to near ambient pressure water vapor or atomic hydrogen species,while partial surface hydroxylation happens on bilayer ZnO under the same gaseous exposure conditions.展开更多
Our scanning tunneling microscopy (STM) study observes, for the first time, twin domain boundary (TDB) formations on the surface of WTe2 single crystal, which is glued by solidifying indium to Si substrate. In these T...Our scanning tunneling microscopy (STM) study observes, for the first time, twin domain boundary (TDB) formations on the surface of WTe2 single crystal, which is glued by solidifying indium to Si substrate. In these TDB regions, a large inhomogeneous strain field, especially a critical shear strain of about 7%, is observed by geometric phase analysis. This observation does not obey the old believe that a small mechanical stress is sufficient to drive thermally-induced TDB formations in two-dimensional materials. To resolve the contradiction, we perform density functional theory calculations combined with elasticity theory analysis, which show that TDBs on WTe2 are entirely displacement-induced, for which a critical strain is necessary to overcome the onset barrier.展开更多
Tran smissio n electro n microscopes (TEM) are widely used in nan otech no logy research. However, it is still challe nging to characterize nano scale objects;their small size coupled with dynamical diffraction makes ...Tran smissio n electro n microscopes (TEM) are widely used in nan otech no logy research. However, it is still challe nging to characterize nano scale objects;their small size coupled with dynamical diffraction makes interpret!ng real- or reciprocal-space data difficult. Scanning precession electron diffraction ((S)PED) represents an invaluable contribution, reducing the dynamical contributions to the diffraction pattern at high spatial resolution. Here a detailed analysis of wurtzite InP nanowires (30-40 nm in diameter) containing a screw dislocation and an associated wire lattice torsion is presented. It has been possible to characterize the dislocation with great detail (Burgers and line vector, handedness). Through careful measurement of the strain field and comparison with dynamical electron diffraction simulations, this was found to be compatible with a Burgers vector modulus equal to one hexagonal lattice cell parameter despite the observed crystal rotation rate being larger (ca. 20%) than that predicted by classical elastic theory for the nominal wire diameter. These findings corroborate the importance of the (S)PED technique for characterizing nano scale materials.展开更多
An in teg rated approach combi ning den sity functional theory(DFT)calculati ons and atomic resol utio n sea nning tun neling microscopy(STM)is used to study well-defined iron-doped cobalt oxide nanoislands supported ...An in teg rated approach combi ning den sity functional theory(DFT)calculati ons and atomic resol utio n sea nning tun neling microscopy(STM)is used to study well-defined iron-doped cobalt oxide nanoislands supported on Au(111).The focus is on the structure and distribution of Fe dopants within these nanoislands of CoO as a function of Fe to Co ratio.The DFT and STM results agree strongly and complement each other to allow for a more complete un dersta nding of the dopa nt structure trends on the nano scale.Using Fe as a marker,we first find that the stacki ng seque nee of the moire structure of the host cobalt oxide nano islands can be ide ntified un ambiguously through a combinati on of DFT and STM.Using the distinct con trast of the embedded Fe dopa nt atoms as observed with atom-resolved STM,we find correlatio ns betwee n Fe dopa nt positi on and the CoO/Au(111)moire patter n at varyi ng Fe dopa nt den sities.Formatio n of Fe-dopa nt clusters within the nano islands is investigated in detail through DFT and found to agree with the dopant patter ns observed in STM.We find that the structural effects of Fe dopants throughout the nanoislands with the basal planes and the two types of edges—the oxygen and metal edges—have different nature.Both DFT calculations and STM images show a strong preferenee for Fe dopants to be located directly on or near the oxygen edge of the nanoislands as opposed to being directly on or n ear the metal edge.Take n together,our results illustrate that Fe dopa nt incorporati on and distributi on within CoO nanoislands are highly an isotropic and gover ned by both the moire structure of the basal planes as well as nano-size effects present at the under-coordinated edges of different local geometry and chemistries.展开更多
文摘目的观察气管导管(endotracheal tube,ETT)表面细菌定植及生物膜(biofilm,BF)形成,探讨其与机械通气新生儿伴发下呼吸道感染之间的相关性。方法以我院2005年1至6月,经治的20例机械通气新生儿为研究对象,观察机械通气过程中下呼吸道感染发生情况,收集第一次拔除或更换的 ETT,扫描电镜(Scanning Electron Microscopy,SEM)观察 ETT 表面 BF(ETT-BF)形成情况及结构,并对 ETT 表面和下呼吸道分泌物进行细菌分离、鉴定和药敏分析。结果①20例中13例机械通气前并不存在下呼吸道感染,在机械通气过程伴发了下呼吸道感染,并在整个机械通气期间持续存在;其中有9例 ETT 留置时间与机械通气时间一致(平均机械通气时间为3.6 d)。②SEM 观察发现留置时间超过1 d 的 ETT 表面细菌定植增加(12/20),3 d 左右细菌在 ETT 表面初步形成 BF,超过3 d 表面 BF 结构更加成熟复杂。③ETT 表面培养阳性14例(包括正常菌群4例),分离得到病原菌7种;下呼吸道分泌物培养阳性13例(包括正常菌群1例),分离得到病原菌10种;其中7例 ETT表面和下呼吸道分泌物同时分离得到同种菌种,其 ETT 留置时间为(3.2±1)d,占 ETT 培养阳性的50%。④ETT 表面和下呼吸道分泌物分离得到的 G^-细菌均对抗生素多重耐药。结论 ETT 表面细菌定植及 BF 形成与长时间机械通气新生儿伴发下呼吸道感染之间可能存在一定相关性,ETT-BF 可能是其感染持续存在的一个病原来源。
文摘How do you get information from an article as much and fast as possible while you are reading? It is a very important thing for us——Chinese readers. Reading is an important element in our English study. Mastering reading skills will help increase our reading speed and comprehend what we read. Now several reading skills are to be discussed in this paper.
基金This work was supported by the National Natural Science Foundation of China(Nos.51861135201,5147200i,21473001,51290272,and 61774003)the Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics(No.KF201601).
文摘Exploring high-efficient catalysts for hydrogen evolution reaction(HER)has become very urgeht for resolving the energy related issues.Recently,two-dimensional layered MoS2 and its heterostructures with graphene or other traditional photocatalysts have presented great potentials for electrocatalytic and photocatalytic HER applications.On-site investigations of the atomic-scale structures and local electronic properties of the catalytically active sites are the key points for understanding the internal mechanisms,which however are hard to be achievec from the practical systems.Hereby,this review focuses on the recent progresses on the on-site scanning tunneling microscopy/spectroscopy investigations of the atomic structures and electronic properties of the ultrahigh-vacuum deposited and chemical vapor deposition(CVD)synthesized monolayer MoS2 and MoSz/graphene vertical stacks on the electrodes of Au(111)and Au foils.The correlations between the respective HER activities,edge types and edge electronic states are comparatively introduced.Secondly,this review also introduces thephotocatalytic HER applications of CVD-grown MoS2/WS2 and WS/MoS2 vertical stacks on Au foils,mainly considering of their type-ll band.alignments and the novel interlayer charge transfer behaviors.Finally,future research directions are also proposed for in-depth understanding of the catalytic mechanism,as well as for exploring more efficient HER catalysts.
基金the National Natural Science Foundation of China(Nos.51472008,51861135201,51290272,61774003,51502007,and 51672007)the National Key Research and Development Program of China(Nos.2016YFA0200103,2017YFA0205700,and 2017YFA0304600)+1 种基金the Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics(Nos.KF201601 and KF201604)"2011 Program”Peking-Tsinghua-IOP Collaborative Innovation Center of Quantum Matter.
文摘Vertical heterostructures based on two-dimensional(2D)materials have attracted widespread interest for their numerous applications in electronic and optoelectronic devices.Herein,we report the direct construct!on of an abnormal graphene/ReSe2 stack on Au foils by a two-step chemical vapor deposition(CVD)strategy.During the second growth stage,mono layer ReSe2 is found to prefere ntially evolve at the irUerface between the first-grown graphene layer and the Au substrate.The unusual stacking behavior is unraveled by in-situ"cutting open"the upper graphene from the defects to expose the lower ReSe2 using scanning tunneling microscopy(STM).From combination of these results with density functional theory calculations,the domain boundaries and edge sites of graphene are proposed to be adsorption sites for Re and Se precursors,further facilitating the growth of ReSe2 at the van der Waals gap of graphene/Au.This work hereby offers an intriguing strategy for obtaining vertical 2D heterostructures featured with an ultra-clean interface and a designed stacking geometry.
文摘Graphene-h-BN hybrid nanostructures are grown in one step on the Pt(111) surface by ultra-high vacuum chemical vapor deposition using a single precursor,the dimethylamino borane complex.By varying the deposition conditions,different nanostructures ranging from a fully continuous hybrid monolayer to well-separated Janus nanodots can be obtained.The growth starts with heterogeneous nucleation on morphological defects such as Pt step edges and proceeds by the addition of small clusters formed by the decomposition of the dimethylamino borane complex.Scanning tunneling microscopy measurements indicate that a sharp zigzag in-plane boundary is formed when graphene grows aligned with the Pt substrate and consequently with the h-BN layer as well.When graphene is rotated by 30°,the graphene armchair edges are seamlessly connected to h-BN zigzag edges.This is confirmed by a thorough density functional theory (DFT) study.Angle resolved photoemission spectroscopy (ARPES) data suggests that both h-BN and graphene present the typical electronic structure of self-standing non-interacting materials.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21825203,91545204,21688102,and 21621063)the National Key Research and Development Program of China(Nos.2016YFA0200200 and 2017YFB0602205)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB17020000)The authors thank the support for Nano-X from Suzhou Institute of Nano-Tech and Nano-Bionics(SINANO).The fruitful discussion with Yuemin Wang in Karlsruhe Institute of Technology(KIT)is highly appreciated.
文摘Ultrathin ZnO nano structures prese nt in teresti ng two-dimensi on al(2D)graphene-like structure in contrast to wurtzite structure in bulk ZnO.Growth on Au(111)has been regarded as a well-established route to the 2D ZnO layers while controlled growth of uniform ZnO nano structures remains as a challe nge.Here,reactive deposition of Zn in O3 and NO2 was employed,which is investigated by sea nning tunneling microscopy and X-ray photoelectr on spectroscopy(XPS).We dem on strate that uniform ZnO mono layer nanoislands and films can be obtained on Au(111)using O3 and uniform ZnO bilayer nanoislands and films form on Au(111)using NO2,respectively.Formation of atomic oxyge n overlayers on Au(111)via exposure to O3 is critical to the formatio n of uniform ZnO mono layer nano structures atop.Near ambient pressure XPS studies revealed that n early full hydroxy lati on occurs on mono layer ZnO structures upon exposure to near ambient pressure water vapor or atomic hydrogen species,while partial surface hydroxylation happens on bilayer ZnO under the same gaseous exposure conditions.
基金We thank the Ministry of Science and Technology of China (Nos. 2016YFA0301003 and 2016YFA0300403)the National Natural Science Foundation of China (Nos. 11521404, 11634009, U1632102, 11504230, 11674222, 11574202, 11674226, 11574201, 11655002, and U1632272) for partial support+4 种基金W Y. X. was supported by the National Science Foundation Award (No. DMR-1305293)S. B.乙 was supported by the US Department of Energy (DOE)(No. DESC0002623)The supercomputer time sponsored by National Energy aesearch Scientific Computing Center (NERSC) under DOE contract (No. DE-AC02-05CH11231)the Center for Computational Innovations (CCI) at Rensselaer Polytechnic Institute (RPI) are also acknowledgedThis project has been supported by a grant &om Science and Technology Commission of Shanghai Municipality (No. 16DZ2260200) and the Strategic Priority Research Program of Chinese Academy of Sciences (No. XDB28000000).
文摘Our scanning tunneling microscopy (STM) study observes, for the first time, twin domain boundary (TDB) formations on the surface of WTe2 single crystal, which is glued by solidifying indium to Si substrate. In these TDB regions, a large inhomogeneous strain field, especially a critical shear strain of about 7%, is observed by geometric phase analysis. This observation does not obey the old believe that a small mechanical stress is sufficient to drive thermally-induced TDB formations in two-dimensional materials. To resolve the contradiction, we perform density functional theory calculations combined with elasticity theory analysis, which show that TDBs on WTe2 are entirely displacement-induced, for which a critical strain is necessary to overcome the onset barrier.
文摘Tran smissio n electro n microscopes (TEM) are widely used in nan otech no logy research. However, it is still challe nging to characterize nano scale objects;their small size coupled with dynamical diffraction makes interpret!ng real- or reciprocal-space data difficult. Scanning precession electron diffraction ((S)PED) represents an invaluable contribution, reducing the dynamical contributions to the diffraction pattern at high spatial resolution. Here a detailed analysis of wurtzite InP nanowires (30-40 nm in diameter) containing a screw dislocation and an associated wire lattice torsion is presented. It has been possible to characterize the dislocation with great detail (Burgers and line vector, handedness). Through careful measurement of the strain field and comparison with dynamical electron diffraction simulations, this was found to be compatible with a Burgers vector modulus equal to one hexagonal lattice cell parameter despite the observed crystal rotation rate being larger (ca. 20%) than that predicted by classical elastic theory for the nominal wire diameter. These findings corroborate the importance of the (S)PED technique for characterizing nano scale materials.
基金A.V.acknowledges the Canadian Institute for Advanced Research(CIFAR)for support through the Bio-inspired Solar Energy Program.J.V.L.and J.R.-F.acknowledge the VILLUM foundation.Z.Z.S.would like to acknowledge financial support from the China Scholarship Council(CSC).L.Z.,T.T.,and A.V.would like to acknowledge the use of the computer time allocation at the National Energy Research Scientific Computing Center(NERSC),a DOE Office of Science User Facility supported by the Office of Science of the U.S.Department of Energy under Contract No.DE-AC02-05CH11231the Extreme Science and Engineering Discovery Environment(XSEDE)supported through National Science Foundation Energy under Award Number CHE160084.
文摘An in teg rated approach combi ning den sity functional theory(DFT)calculati ons and atomic resol utio n sea nning tun neling microscopy(STM)is used to study well-defined iron-doped cobalt oxide nanoislands supported on Au(111).The focus is on the structure and distribution of Fe dopants within these nanoislands of CoO as a function of Fe to Co ratio.The DFT and STM results agree strongly and complement each other to allow for a more complete un dersta nding of the dopa nt structure trends on the nano scale.Using Fe as a marker,we first find that the stacki ng seque nee of the moire structure of the host cobalt oxide nano islands can be ide ntified un ambiguously through a combinati on of DFT and STM.Using the distinct con trast of the embedded Fe dopa nt atoms as observed with atom-resolved STM,we find correlatio ns betwee n Fe dopa nt positi on and the CoO/Au(111)moire patter n at varyi ng Fe dopa nt den sities.Formatio n of Fe-dopa nt clusters within the nano islands is investigated in detail through DFT and found to agree with the dopant patter ns observed in STM.We find that the structural effects of Fe dopants throughout the nanoislands with the basal planes and the two types of edges—the oxygen and metal edges—have different nature.Both DFT calculations and STM images show a strong preferenee for Fe dopants to be located directly on or near the oxygen edge of the nanoislands as opposed to being directly on or n ear the metal edge.Take n together,our results illustrate that Fe dopa nt incorporati on and distributi on within CoO nanoislands are highly an isotropic and gover ned by both the moire structure of the basal planes as well as nano-size effects present at the under-coordinated edges of different local geometry and chemistries.
