During the past decades,major advances have been made in both the generation and detection of infrared light;however,its efficient wavefront manipulation and information processing still encounter great challenges.Eff...During the past decades,major advances have been made in both the generation and detection of infrared light;however,its efficient wavefront manipulation and information processing still encounter great challenges.Efficient and fast optoelectronic modulators and spatial light modulators are required for mid-infrared imaging,sensing,security screening,communication and navigation,to name a few.However,their development remains elusive,and prevailing methods reported so far have suffered from drawbacks that significantly limit their practical applications.In this study,by leveraging graphene and metasurfaces,we demonstrate a high-performance free-space mid-infrared modulator operating at gigahertz speeds,low gate voltage and room temperature.We further pixelate the hybrid graphene metasurface to form a prototype spatial light modulator for high frame rate single-pixel imaging,suggesting orders of magnitude improvement over conventional liquid crystal or micromirror-based spatial light modulators.This work opens up the possibility of exploring wavefront engineering for infrared technologies for which fast temporal and spatial modulations are indispensable.展开更多
Recently,the development and fabrication of electrode component of the solid oxide fuel cell(SOFC)have gained a significant importance,especially after the advent of electrode supported SOFCs.The function of the elect...Recently,the development and fabrication of electrode component of the solid oxide fuel cell(SOFC)have gained a significant importance,especially after the advent of electrode supported SOFCs.The function of the electrode involves the facilitation of fuel gas diffusion,oxidation of the fuel,transport of electrons,and transport of the byproduct of the electrochemical reaction.Impressive progress has been made in the development of alternative electrode materials with mixed conducting properties and a few of the other composite cermets.During the operation of a SOFC,it is necessary to avoid carburization and sulfidation problems.The present review focuses on the various aspects pertaining to a potential electrode material,the double perovskite,as an anode and cathode in the SOFC.More than 150 SOFCs electrode compositions which had been investigated in the literature have been analyzed.An evaluation has been performed in terms of phase,structure,diffraction pattern,electrical conductivity,and power density.Various methods adopted to determine the quality of electrode component have been provided in detail.This review comprises the literature values to suggest possible direction for future research.展开更多
The main concerns in the world today,especially in the energy field,are subjected to clean,efficient,and durable sources of energy.These three aspects are the main goals that scientist are paying attention to.However,...The main concerns in the world today,especially in the energy field,are subjected to clean,efficient,and durable sources of energy.These three aspects are the main goals that scientist are paying attention to.However,the various types of energy resources include fossil and sustainable ones,but still some challenges are chasing these kinds from energy conversion,storage,and efficiency.Hence,the most reliable and considered energy resource nowadays is the utilized one which is as highly efficient,clean,and everlasting as possible.So,in this review,an attempt is made to highlight one of the promising types as a clean and efficient energy resource.Solid oxide fuel cell(SOFC)is the most efficient type of the fuel cell types involved with hydrogen and hydrocarbon-based fuels,especially when it works with combined heat and power(CHP).The importance of this type is due to its nature of work as conversion tool from chemical to electrical for generation of power without noise,pollution,and can be safely handled.展开更多
Pennisetum purpureum is one of the most invasive perennial grasses of the Poaceae family,which are abundant in south-east Asia including Brunei Darussalam.The pyrolysis process at a slow heating rate proved to be high...Pennisetum purpureum is one of the most invasive perennial grasses of the Poaceae family,which are abundant in south-east Asia including Brunei Darussalam.The pyrolysis process at a slow heating rate proved to be highly promising for biochar production.The production and characterization of different Pennisetum purpureum biochars have been investigated at the pyrolysis temperatures of 400℃,500℃and 600℃with a heating and nitrogen flow rate of 5℃/min and 0.5 L/min,respec-tively.The observed higher heating values were 22.18 MJ/kg,23.02 MJ/kg,23.75 MJ/kg,and the alkaline pH were 9.10,9.86,10.17 for the biochar at 400℃,500℃,600℃temperatures,respectively.The water holding capacity was one hundred percent for all biochars and continued to increase for higher pyrolysis temperature.SEM images show that the porosity of the biochars has been enhanced with increased temperatures due to the rearrangement of crystallinity and aromaticity.On the other hand,the yields of biochar have been decreased from 35.13%to 23.02%for the increase of pyrolysis temperature from 400℃to 600℃.Energy dispersive X-ray analysis shows that the O/C atomic ratios were 0.15,0.08 and 0.06 for the biochar of 400,500 and 600℃which validates the improvement in heating values.FT-IR analysis revealed that the available functional groups in the biochars were C-O,C=C,and C-H.Thermogravimetric analysis(TGA)under pyrolysis condi-tion showed residue of 46.56%,51.13%and 55.67%from the biochar at 400,500,and 600℃,respectively.The derivative thermogravimetry(DTG)graph indicates that the degradation rate is higher for 400℃biochar than the 600℃biochar.展开更多
基金the Los Alamos National Laboratory LDRD ProgramAFOSR under contract no.FA9550-12-0491the AFOSR YIP program under Contract no.FA9550-16-1-0183.
文摘During the past decades,major advances have been made in both the generation and detection of infrared light;however,its efficient wavefront manipulation and information processing still encounter great challenges.Efficient and fast optoelectronic modulators and spatial light modulators are required for mid-infrared imaging,sensing,security screening,communication and navigation,to name a few.However,their development remains elusive,and prevailing methods reported so far have suffered from drawbacks that significantly limit their practical applications.In this study,by leveraging graphene and metasurfaces,we demonstrate a high-performance free-space mid-infrared modulator operating at gigahertz speeds,low gate voltage and room temperature.We further pixelate the hybrid graphene metasurface to form a prototype spatial light modulator for high frame rate single-pixel imaging,suggesting orders of magnitude improvement over conventional liquid crystal or micromirror-based spatial light modulators.This work opens up the possibility of exploring wavefront engineering for infrared technologies for which fast temporal and spatial modulations are indispensable.
文摘Recently,the development and fabrication of electrode component of the solid oxide fuel cell(SOFC)have gained a significant importance,especially after the advent of electrode supported SOFCs.The function of the electrode involves the facilitation of fuel gas diffusion,oxidation of the fuel,transport of electrons,and transport of the byproduct of the electrochemical reaction.Impressive progress has been made in the development of alternative electrode materials with mixed conducting properties and a few of the other composite cermets.During the operation of a SOFC,it is necessary to avoid carburization and sulfidation problems.The present review focuses on the various aspects pertaining to a potential electrode material,the double perovskite,as an anode and cathode in the SOFC.More than 150 SOFCs electrode compositions which had been investigated in the literature have been analyzed.An evaluation has been performed in terms of phase,structure,diffraction pattern,electrical conductivity,and power density.Various methods adopted to determine the quality of electrode component have been provided in detail.This review comprises the literature values to suggest possible direction for future research.
基金supported by the Graduate Research Scholarship(GRS)granted by the Graduate Research Office of Univeristi Brunei Darussalam.
文摘The main concerns in the world today,especially in the energy field,are subjected to clean,efficient,and durable sources of energy.These three aspects are the main goals that scientist are paying attention to.However,the various types of energy resources include fossil and sustainable ones,but still some challenges are chasing these kinds from energy conversion,storage,and efficiency.Hence,the most reliable and considered energy resource nowadays is the utilized one which is as highly efficient,clean,and everlasting as possible.So,in this review,an attempt is made to highlight one of the promising types as a clean and efficient energy resource.Solid oxide fuel cell(SOFC)is the most efficient type of the fuel cell types involved with hydrogen and hydrocarbon-based fuels,especially when it works with combined heat and power(CHP).The importance of this type is due to its nature of work as conversion tool from chemical to electrical for generation of power without noise,pollution,and can be safely handled.
基金Md Sumon Reza is highly acknowledged in the University Graduate Scholarship from UBD.The author is also grateful to Dr.Nikdalila Radenahmad for supporting this work.This project was funded by a UBD competitive research grant:UBD/OVACRI/CRGWG(006)/161201.
文摘Pennisetum purpureum is one of the most invasive perennial grasses of the Poaceae family,which are abundant in south-east Asia including Brunei Darussalam.The pyrolysis process at a slow heating rate proved to be highly promising for biochar production.The production and characterization of different Pennisetum purpureum biochars have been investigated at the pyrolysis temperatures of 400℃,500℃and 600℃with a heating and nitrogen flow rate of 5℃/min and 0.5 L/min,respec-tively.The observed higher heating values were 22.18 MJ/kg,23.02 MJ/kg,23.75 MJ/kg,and the alkaline pH were 9.10,9.86,10.17 for the biochar at 400℃,500℃,600℃temperatures,respectively.The water holding capacity was one hundred percent for all biochars and continued to increase for higher pyrolysis temperature.SEM images show that the porosity of the biochars has been enhanced with increased temperatures due to the rearrangement of crystallinity and aromaticity.On the other hand,the yields of biochar have been decreased from 35.13%to 23.02%for the increase of pyrolysis temperature from 400℃to 600℃.Energy dispersive X-ray analysis shows that the O/C atomic ratios were 0.15,0.08 and 0.06 for the biochar of 400,500 and 600℃which validates the improvement in heating values.FT-IR analysis revealed that the available functional groups in the biochars were C-O,C=C,and C-H.Thermogravimetric analysis(TGA)under pyrolysis condi-tion showed residue of 46.56%,51.13%and 55.67%from the biochar at 400,500,and 600℃,respectively.The derivative thermogravimetry(DTG)graph indicates that the degradation rate is higher for 400℃biochar than the 600℃biochar.
