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Osiers-sprout-like heteroatom-doped carbon nanofibers as ultrastable anodes for lithium/sodium ion storage

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Nano Research 2018年第7期11卷 3791-3801页

作者： Hang Zhang Guanhua Zhang Zhiqin Li Ke Qu Huimin Shi Qingfeng Zhang Huigao Duan Jianhui Jiang College of Chemistry and Chemical Engineering Hunan University Changsha 410082 China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body National Engineering Research Center for High Efficiency Grinding College of Mechanical and Vehicle Engineering Hunan University Changsha 410082 China Department of Materials Science and Engineering Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge Massachusetts 02139 USA

We report an in situ carbothermic reduction process to prepare osiers-sprout-like heteroatom-doped carbon nanofibers. The dosage of copper salts and a unique annealing process have a crucial effect on the development of this unique carbon structure. A systematic analysis is performed to elucidate the possible mechanism of synthesis of the carbon nanofibers decorated with carbon bubbles. As anodes for rechargeable lithium/sodium ion batteries, the heteroatom-doped nanofibers exhibit high reversible capacities and satisfactory long-term cycling stabilities. The osiers-sprout-like heteroatom-doped carbon nanofiber electrodes deliver an ultrastable cycling performance with reversible capacities of 480 and 160 mAh·g^-1 for lithium-ion and sodium-ion batteries after 900 cycles at a current density of 800 mA·g^-1, respectively.

关键词： doped carbon nanofibers carbothermic reduction anodes lithium-ion batteries sodium-ion batteries

New spectroscopic methods for environmental measurement and monitoring

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Chinese Journal of Chemistry 1999年第3期17卷 204-211,201页

作者： STEINFELD Jeffrey I. Department of Chemistry Massachusetts Institute of Technology Cambridge Mass. 02139 USA

The ability to monitor a broad range of chemical species in the atmosphere, geosphere, and hydrosphere is a key technology for addressing global environmental issues. This report surveys several high sensitivity spectroscopic techniques for this purpose, including Frequency-Modulation-Enhanced Remote Sensing, Intra Cavity Laser Absorption Spectroscopy, Cavity Ring Down Spectroscopy, and Raman Spectroscopy.

关键词： Green Chemistry sustainability environmental monitoring spectroscopy Raman

Hesitant steps from the artificial skin to organ regeneration

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Regenerative Biomaterials 2018年第4期5卷 189-195页

作者： Ioannis V.Yannas Department of Mechanical Engineering Massachusetts Institute of TechnologyCambridgeMA 02139USA

This is a historical account of the steps,both serendipitous and rational,that led my group of students and colleagues at MIT and Harvard Medical School to discover induced organ *** research led to methods for growing back in adult mammals three heavily injured organs,skin,peripheral nerves and the *** conclude that regeneration in adults is induced by a modification of normal wound healing.

关键词： skin regeneration peripheral nerve regeneration contraction blocking dermis regeneration template

Effects of Precise FRF Measurements for Frequency Based Substructuring

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Sound & Vibration 2018年第1期52卷 3-7页

作者： Julie Harvie Peter Avitabile Structural Dynamics and Acoustic Systems Laboratory University of Massachusetts Lowell One University Avenue LowellMassachusetts 01854

Impedance modeling is often utilized to generate frequency response functions of an assembled system using modal characteristics of individual *** slight inaccuracies are manifested in the characteristics of the *** those inaccuracies may seem minor in regards to the component for a traditional modal model,the inaccuracies can be amplified when impedance modeling is *** based substructuring involves inversion of the frequency response functions and therefore requires considerable accuracy for the measurement,particularly in the area of *** this study,some aspects of frequency based substructuring were explored,namely difficulties that might be encountered in experimental testing related to drive point *** majority of studies were performed using analytical models to minimize contamination of *** study focuses on connection point measurements where the actual location might be inaccessible due to physical constraints such as hardware,holes,*** the effect of introducing slight inaccuracies to the location of the drive point measurement was studied,along with other aspects related to the accuracy of the critical connection measurement.

关键词： measurement. modal utilized

Bloch surface eigenstates within the radiation continuum

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Light(Science & Applications) 2013年第1期2卷 113-118页

作者： Chia Wei Hsu Bo Zhen Song-Liang Chua Steven G Johnson John D Joannopoulos Marin Soljacic Research Laboratory of Electronics Massachusetts Institute of TechnologyCambridgeMA 02139USA Department of Physics Harvard UniversityCambridgeMA 02138USA Department of Mathematics Massachusetts Institute of TechnologyCambridgeMA 02139USA

From detailed numerical calculations,we demonstrate that in simple photonic crystal structures,a discrete number of Bloch surface-localized eigenstates can exist inside the continuum of free-space *** to the free space causes the surface modes to leak,but the forward and back-reflected leakage may interfere destructively to create a perfectly bound surface state with zero *** perform analytical temporal coupled-mode theory analysis to show the generality of such phenomenon and its robustness from variations of system ***,time-reversal invariance,two-fold rotational symmetry and a perfectly reflecting boundary are necessary for these unique states.

关键词： bound state in continuum embedded eigenvalue photonic crystal surface mode

Simple glycolipids of microbes:Chemistry,biological activity and metabolic engineering

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Synthetic and Systems Biotechnology 2018年第1期3卷 3-19页

作者： Ahmad Mohammad Abdel-Mawgoud Gregory Stephanopoulos Department of Chemical Engineering Massachusetts Institute of Technology77 Massachusetts Ave.CambridgeMA 02139USA

Glycosylated lipids(GLs)are added-value lipid derivatives of great *** their interesting surface activities that qualify many of them to act as excellent ecological detergents,they have diverse biological activities with promising biomedical and cosmeceutical ***,especially those of microbial origin,have interesting antimicrobial,anticancer,antiparasitic as well as immunomodulatory ***,GLs are hardly accessing the market because of their high cost of *** believe that experience of metabolic engineering(ME)of microbial lipids for biofuel production can now be harnessed towards a successful synthesis of microbial GLs for biomedical and other *** review presents chemical groups of bacterial and fungal GLs,their biological activities,their general biosynthetic pathways and an insight on ME strategies for their production.

关键词： Biosurfactant Glycolipids biosynthesis Glycosyl/acyl transferases Glycosides Physiological roles Lipid biotechnology

Highly sensitive gas sensors on low-cost nanostructured polymer substrates

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International Journal of Smart and Nano Materials 2011年第1期2卷 1-8页

作者： Haibin Huo Haizhou Ren Cong Wang Mengyan Shen Department of Physics and Applied Physics and Nanomanufacturing CenterUniversity of Massachusetts Lowell1 University AvenueLowellMassachusetts 01854USA

SnO_(2)thin-film gas sensors have been successfully fabricated on nanospiked polyurethane polymer surfaces,which are replicated by a low-cost soft nanolithography method from silicon nanospike structures formed with femtosecond laser *** revealed significant response to carbon monoxide(CO)gas at room temperature,which is considerably different from the sensors of SnO_(2)thin films coated on smooth surfaces that show no response to CO gas at room *** high area/volume ratio and sharp structures of the nanospikes enhance the sensitivity of SnO_(2)at room *** will greatly decrease the electrical power consumption of the gas sensor and the cost for calibrations,and has great potential for application in other sensing systems.

关键词： thin-film sensor tin oxide carbon monoxide gas nanospike soft nanolithography

Buckled MEMS Beams for Energy Harvesting from Low Frequency Vibrations

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Research 2019年第1期2019卷 697-710页

作者： Ruize Xu Haluk Akay Sang-Gook Kim massachusetts Institute of Technology Mechanical Engineering DepartmentCambridgeMA 02139USA

Vibration energy harvesters based on the resonance of the beam structure work efectively only when the operating frequency window of the beam resonance matches with the available vibration *** of the resonating MEMS structures can operate with low frequency,low amplitude,and unpredictable ambient vibrations since the resonant frequency goes up very high as the structure gets *** buckled beam energy harvester is therefore developed for lowering the operating frequency window below 100Hz for the frst time at the MEMS *** design does not rely on the resonance of the MEMS structure but operates with the large snapping motion of the beam at very low frequencies when input energy overcomes an energy threshold.A fully functional piezoelectric MEMS energy harvester is designed,monolithically fabricated,and *** electromechanical lumped parameter model is developed to analyze the nonlinear dynamics and to guide the design of the nonlinear oscillator based energy *** beam structure with residual stress induced buckling is achieved through the progressive residual stress control of the deposition processes along the fabrication *** profle of the released device shows bistable buckling of 200μm which matches well with the amount of buckling *** testing demonstrates the energy harvester operates with 50%bandwidth under 70Hz at 0.5g input,operating conditions that have not been demonstrated by MEMS vibration energy harvesters before.

关键词： buckling overcome steps

Advanced engineering and biomimetic materials for bone repair and regeneration

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Frontiers of Materials Science 2013年第4期7卷 313-334页

作者： Lei YANG Chao ZHONG Institute of Orthopaedics Department of Orthopaedic Surgery at the First Affiliated Hospital Soochow University Suzhou 215006 China Research Laboratory of Electronics (RLE) Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139-4307 USA Synthetic Biology Center Massachusetts Institute of Technology Cambridge Massachusetts 02139-4307 USA

Over the past decade, there has been tremendous progress in developing advanced biomaterials for tissue repair and regeneration. This article reviews the frontiers of this field from two closely related areas, new engineering materials for bone substitution and biomimetic mineralization for bone-like nanocomposites. Rather than providing an exhaustive overview of the literature, we focus on several representative directions. We also discuss likely future trends in these areas, including synthetic biology-enabled biomaterials design and multifunctional implant materials for bone repair and regeneration.

关键词： bone engineering material biomimetic material implant biomineralization