Although abundant research on the anisotropy of van der Waals(vd W)materials has been published,we undertake an in-depth study of their optical properties as they have an important guiding role for light control in tw...Although abundant research on the anisotropy of van der Waals(vd W)materials has been published,we undertake an in-depth study of their optical properties as they have an important guiding role for light control in two-dimensional(2D)nanospace.As an example,we study the reflectance of few-layered black phosphorus(BP)in the total internal reflection(TIR)mode in detail.We demonstrate that its optical anisotropy can be changed on a large scale by varying the incident angles,polarization states,and the in-plane rotation angles of the BP samples.Theoretical analysis indicates that the phenomena observed are common to all the atom-thick biaxial crystals,so these conclusions can be widely applied to other anisotropic 2D materials.This research furthers the current understanding of the properties of BP more comprehensively,and provides guidance for developing new optoelectronic applications,especially when BP and other atom-thick biaxial crystals are integrated with TIR devices.展开更多
Many animals migrate during the breeding season.It is important to study the patterns of breeding migration of wild animals,especially rare and endangered species.However,current data acquisition methods are too coars...Many animals migrate during the breeding season.It is important to study the patterns of breeding migration of wild animals,especially rare and endangered species.However,current data acquisition methods are too coarse and imprecise for investigating the circadian rhythms of migrations in amphibians.Based on the frustrated total reflection image(FTRI),we developed a new device and recorded the precise migration time of an endangered salamander,Liangshantriton taliangensis.During the breeding period,a total of 33 individuals were effectively recorded.Analysis of the data indicated that the circadian rhythm of breeding migration in L.taliangensis was bimodal,and migration mainly occurred from 05:00 to 13:00(81.82%of the total migration records).The average relative activity intensity index(RAI)of breeding migration peaked in the temperature range of 14.0–16.0°C.With increased average relative air humidity,the activity intensity first increased and then decreased,reaching a peak in the humidity range of 91.0%–97.0%.These results demonstrate that our new device is a viable and accurate method for recording the migration time of target species.It is important to reveal the breeding migration pattern of L.taliangensis,which is important for the conservation of this species.Meanwhile,this new device can be used for field monitoring and conservation studies of amphibians,reptiles and other animals.展开更多
For optimization of production processes and product quality,often knowledge of the factors influencing the process outcome is compulsory.Thus,process analytical technology(PAT)that allows deeper insight into the proc...For optimization of production processes and product quality,often knowledge of the factors influencing the process outcome is compulsory.Thus,process analytical technology(PAT)that allows deeper insight into the process and results in a mathematical description of the process behavior as a simple function based on the most important process factors can help to achieve higher production efficiency and quality.The present study aims at characterizing a well-known industrial process,the transesterification reaction of rapeseed oil with methanol to produce fatty acid methyl esters(FAME)for usage as biodiesel in a continuous micro reactor set-up.To this end,a design of experiment approach is applied,where the effects of two process factors,the molar ratio and the total flow rate of the reactants,are investigated.The optimized process target response is the FAME mass fraction in the purified nonpolar phase of the product as a measure of reaction yield.The quantification is performed using attenuated total reflection infrared spectroscopy in combination with partial least squares regression.The data retrieved during the conduction of the DoE experimental plan were used for statistical analysis.A non-linear model indicating a synergistic interaction between the studied factors describes the reactor behavior with a high coefficient of determination(R^(2))of 0.9608.Thus,we applied a PAT approach to generate further insight into this established industrial process.展开更多
The study of the mineral and organic content of the Allende meteorite is important for our understanding of the molecular evolution of the universe as well as the ancient Earth. Previous studies have characterized the...The study of the mineral and organic content of the Allende meteorite is important for our understanding of the molecular evolution of the universe as well as the ancient Earth. Previous studies have characterized the magnetic minerals present in ordinary and carbonaceous chondrites, providing information on the evolution of magnetic fields. The interaction of organic compounds with magnetic minerals is a possible source of chemical diversity, which is crucial for molecular evolution. Carbon compounds in meteorites are of great scientific interest for a variety of reasons, such as their relevance to the origins of chirality in living organisms. This study presents the characterization of organic and mineral compounds in the Allende meteorite. The structural and physicochemical characterization of the Allende meteorite was accomplished through light microscopy, powder X-ray diffraction with complementary Rietveld refinement, Raman and infrared spectroscopy, mass spectrometry, scanning electron microscopy, and atomic force microscopy using magnetic signal methods to determine the complex structure and the interaction of organic compounds with magnetic Ni-Fe minerals. The presence of Liesegang-like patterns of chondrules in fragments of the Allende structure may also be relevant to understanding how the meteorite was formed. Other observations include the presence of magnetic materials and nanorod-like solids with relatively similar sizes as well as the heterogeneous distribution of carbon in chondrules. Signals observed in the Raman and infrared spectra resemble organic compounds such as carbon nanotubes and peptide-like molecules that have been previously reported in other meteorites, making the Mexican Allende meteorite a feasible sample for the study of the early Earth and exoplanetary bodies.展开更多
The spatial and temporal evolution of real contact area of contact interface with loads is a challenge.It is generally believed that there is a positive linear correlation between real contact area and normal load.How...The spatial and temporal evolution of real contact area of contact interface with loads is a challenge.It is generally believed that there is a positive linear correlation between real contact area and normal load.However,with the development of measuring instruments and methods,some scholars have found that the growth rate of real contact area will slow down with the increase of normal load under certain conditions,such as large-scale interface contact with small roughness surface,which is called the nonlinear phenomenon of real contact area.At present,there is no unified conclusion on the explanation of this phenomenon.We set up an experimental apparatus based on the total reflection principle to verify this phenomenon and analyze its mechanism.An image processing method is proposed,which can be used to quantitative analysis micro contact behaviors on macro contact phenomenon.The weighted superposition method is used to identify micro contact spots,to calculate the real contact area,and the color superimposed image is used to identify micro contact behaviors.Based on this method,the spatiotemporal evolution mechanism of real contact area nonlinear phenomena is quantitatively analyzed.Furthermore,the influence of nonlinear phenomenon of real contact area on the whole loading and unloading process is analyzed experimentally.It is found that the effects of fluid between contact interface,normal load amplitude and initial contact state on contact behavior cannot be ignored in large-scale interface contact with small roughness surface.展开更多
Since numerous characteristic absorption lines caused by molecular vibration exist in the midinfrared(MIR)wavelength region,selective excitation or selective dissociation of molecules is possible by tuning the laser w...Since numerous characteristic absorption lines caused by molecular vibration exist in the midinfrared(MIR)wavelength region,selective excitation or selective dissociation of molecules is possible by tuning the laser wavelength to the characteristic absorption lines of target molecules.By applying this feature to the medical fields,less-invasive treatment and non-destructive diagnosis with absorption spectroscopy are possible using tunable MIR lasers.A high-energy nanosecond pulsed MIR tunable laser was obtained with difference-frequency generation(DFG)between a Nd:YAG and a tunable Cr:forsterite lasers.The MIR-DFG laser was tunable in a wavelength range of 5.5–10μm and generated laser pulses with energy of up to 1.4mJ,a pulse width of 5 ns,and a pulse repetition rate of 10 Hz.Selective removal of atherosclerotic lesion was successfully demonstrated with the MIR-DFG laser tuned at a wavelength of 5.75μm,which corresponds to the characteristic absorption of the ester bond in cholesterol esters in the atherosclerotic lesions.We have developed a non-destructive diagnostic probe with an attenuated total reflection(ATR)prism and two hollow optical fibers.An absorption spectrum of cholesterol was measured with the ATR probe by scanning the wavelength of the MIR-DFG laser,and the spectrum was in good agreement with that measured with a commercial Fourier transform infrared spectrometer.展开更多
This work describes synthesis of graphene sheets with modified surface by sodium lauryl sulfate (SLS) surfactant using one-pot solvothermal reaction method. Effect of sodium lauryl sulfate surfactant amount on surface...This work describes synthesis of graphene sheets with modified surface by sodium lauryl sulfate (SLS) surfactant using one-pot solvothermal reaction method. Effect of sodium lauryl sulfate surfactant amount on surface modification level of graphene sheets was investigated. Ether (-S-OR- at 762 cm<sup>-1</sup> - 863 cm<sup>-1</sup>), thiocarbonyl (=C=S at 1050 cm<sup>-1</sup> - 1176 cm<sup>-1</sup>) and sulfoxide (S-O, V<sub>s</sub> and V<sub>as</sub> at 1030 cm<sup>-1</sup> - 1450 cm<sup>-1</sup>) functional groups released from sodium lauryl sulfate (SLS) surfactant during solvothermal reaction and attached on the surface of graphene sheets were detected by (attenuated total reflectance-fast Fourier infrared) ATR-FTIR spectroscopy. (Atomic force microscope) AFM observations revealed apparent surface of graphene sheets modified by surfactant molecules with an average multiple profile of graphene nanosheets ≈ 4.8 nm high. This synthesis way of surface modified graphene sheets can be considered as easy, one-step and cheap method for manufacturing of novel biosurface with graphene, as reinforcement for biopolymer coatings such as ultra-high molecular weight polypropylene (UHMWPE), metallic biomaterials (Ti and Ti alloys) and bioceramics as hydroxyapatite (HA).展开更多
Raman spectroscopy is a common method of studying carbon-based materials such as multi-walled carbon nanotubes (MWCNT). However, the analysis of this technique is non-trivial since recorded spectra may be a convolutio...Raman spectroscopy is a common method of studying carbon-based materials such as multi-walled carbon nanotubes (MWCNT). However, the analysis of this technique is non-trivial since recorded spectra may be a convolution of both molecular vibrations and phonon resonances. The energies of these physical processes may occur in the same energy regime, and hence several analytical approaches can be necessary for a full analysis. Due to the negligible quantities of non-graphitic carbon in MWCNT, the present fitting procedure focuses on understanding phonon resonances to elucidate how varying modifications of MWCNT ultimately influence their graphitic bulk structure. We have found this approach to provide greater insight into the structure of MWCNT when low quantities of amorphous carbon are present, when compared with methods which try to interpret both phonon scattering and molecular vibrations simultaneously. Different pre-treatments for the modification of the graphitic structure of MWCNT are compared, including aqueous acidic and gas phase methods, and statistically evaluated. Focusing on phonon resonances enables one to analyze the reaction process of nitrosulfuric acid pre-treatment at different temperatures. Thereby, it is possible to control the ratio between defects and graphitic structures in MWCNT samples and prepare samples with reproducible D/G ratios.展开更多
In this paper,we examine the tiny polarization rotation effect in total internal reflection due to the spin–orbit interaction of light.We find that the tiny polarization rotation rate will induce a geometric phase gr...In this paper,we examine the tiny polarization rotation effect in total internal reflection due to the spin–orbit interaction of light.We find that the tiny polarization rotation rate will induce a geometric phase gradient,which can be regarded as the physical origin of photonic spin Hall effect.We demonstrate that the spin-dependent splitting in position space is related to the polarization rotation in momentum space,while the spin-dependent splitting in momentum space is attributed to the polarization rotation in position space.Furthermore,we introduce a quantum weak measurement to determine the tiny polarization rotation rate.The rotation rate in momentum space is obtained with 118 nm,which manifests itself as a spatial shift,and the rotation rate in position space is achieved with 38 μrad∕λ,which manifests itself as an angular shift.The investigation of the polarization rotation characteristics will provide insights into the photonic spin Hall effect and will enable us to better understand the spin–orbit interaction of light.展开更多
Y-branching TIR all-optical switch have been fabricated. When the switching optical intensity is 149.9W/mm2, the extinction ratio is 18dB. A theoretical model was also proposed which provided a good fit to the experim...Y-branching TIR all-optical switch have been fabricated. When the switching optical intensity is 149.9W/mm2, the extinction ratio is 18dB. A theoretical model was also proposed which provided a good fit to the experimental data.展开更多
Optical microscopy promises researchers to soe most tiny substances directly.However,the resolution of conventional microscopy is resticted by the diffraction limit.This makes it a challenge to observe subcellular pro...Optical microscopy promises researchers to soe most tiny substances directly.However,the resolution of conventional microscopy is resticted by the diffraction limit.This makes it a challenge to observe subcellular processes happened in nanoscale.The development of super-resolution microscopy provides a solution to this challenge.Here,we briefly review several commonly used super-resolution techniques,explicating their basic principles and applications in biological science,especially in neuroscience.In addition,characteristics and limitations of each techrique are compared to provide a guidance for biologists to choose the most suitable tool.展开更多
Adhesion molecule CD146 (100-130kDa) belongs to the immunoglobulin super family and it is originally identified as a biomarker for melanoma. Recently, CD146 is found as
Design of ultra-wideband antennas is challenging in the stringent requirements that are often conflicting to achieve a wide impedance bandwidth while maintaining high radiation efficiency, uniform gain and compact siz...Design of ultra-wideband antennas is challenging in the stringent requirements that are often conflicting to achieve a wide impedance bandwidth while maintaining high radiation efficiency, uniform gain and compact size. A Multiple-Input Multiple-Output (MIMO) antenna system can enhance the overall antenna performance but at having to overcome new challenges such as reducing the mutual coupling and the correlation between the elements. A printed circular disc compact planar antenna is selected in this work due to its UWB performance and compact size for the MIMO antenna system. A parametric analysis is carried out to achieve an optimal design. The system developed consists of two elements with an overall size of 59 × 27 mm. The designed antenna system operates over the whole of the UWB bandwidth from 3.1 to 10.6 GHz with radiation efficiency up to 85% and reflection coefficients less that ?10 dB. The envelope correlation is less than ?60 dB throughout the UWB band while the diversity gain approaches 10 throughout the entire UWB bandwidth and Total Active Reflection Coefficient (TARC) between the antenna elements is less ?11 dB. Thus the proposed MIMO antenna outperforms similar antenna systems reported in the literature.展开更多
Through interface engineering and content control strategy,a PdBi bimetallic interface structure was constructed for the first time to selectively convert CO_(2)to formate with a remarkably high Faraday efficiency(FEf...Through interface engineering and content control strategy,a PdBi bimetallic interface structure was constructed for the first time to selectively convert CO_(2)to formate with a remarkably high Faraday efficiency(FEformate)of 94%and a partial current density(jformate)of 34 mA·cm^(−2)at−0.8 V vs.reversible hydrogen electrode(RHE)in an H-cell.Moreover,the PdBi interface electrocatalyst even exhibited a high current density of 180 mA·cm^(−2)with formate selectivity up to 92%in a flow cell and could steadily operate for at least 20 h.Electrochemical in-situ attenuated total reflection surface enhanced infrared absorption spectroscopy(ATR-SEIRAS)confirmed that the PdBi interface could greatly weaken the adsorption of*CO intermediates due to electronic and geometric effects.Density functional theory(DFT)calculations also established that the PdBi interface regulated the CO_(2)-to-formate pathway by reducing the energy barrier toward HCOOH and largely weakening the adsorption of*CO intermediates on the catalyst surface.This study reveals that the unique PdBi bimetallic interface can provide a novel platform to study the reaction mechanism through combining in-situ ATR-SEIRAS and DFT calculations.展开更多
T4 polynucleotide kinase(T4 PNK) is a pivotal enzyme for DNA replication, recombination, and DNA damage repair. Herein, a robust single particle counting-based assay has been developed for the high-sensitive determina...T4 polynucleotide kinase(T4 PNK) is a pivotal enzyme for DNA replication, recombination, and DNA damage repair. Herein, a robust single particle counting-based assay has been developed for the high-sensitive determination of T4 PNK activity through only a simple one-step reaction. Taking benefit of the exceptional space-confined enzymatic property of T4 PNK towards DNA substrates on a single nanoparticle,the T4 PNK activity can be precisely determined by counting the fluorescence-positive nanoparticles in a digital manner with a total internal reflection fluorescent microscope(TIRFM). Due to the featured spatial-confined enzymatic property of T4 PNK and the single particle counting-based signal readout, T4PNK can be effectively differentiated from other interfering enzymes. This facile strategy has been also successfully applied to screen T4 PNK inhibitor and accurately determine T4 PNK activity in complex biological samples, paving a potential avenue for the digital analysis of biomarkers.展开更多
We report experimental and mechanistic understanding of methanol oxidation to produce methyl formate using CuO/Ti02-spindle composite as a promising photocatalyst under mild conditions with over 97%conversion and 83%s...We report experimental and mechanistic understanding of methanol oxidation to produce methyl formate using CuO/Ti02-spindle composite as a promising photocatalyst under mild conditions with over 97%conversion and 83%selectivity.The catalysts are obtained via precise depositing of CuO nanoclusters(size:~3.5 nm)at the{101}facet of the TiO2 to optimally tune exciton recombination through oxygen vacancies generation,evidenced by photoluminescence and Raman spectroscopy measurements.The turnover frequency(TOF)and the apparent quantum efficiency(AQE)of the 7%CuO/TiO2-spindle composites reach up to 23.8 molmethanol·gcat^-1·h^-1 and 55.2%at 25℃,respectively,which are substantially higher than these previously reported photocatalysts.Further,the in-situ attenuated total reflection infrared spectroscopy analysis reveals that the methanol oxidation most likely takes place through the conversion of adsorbed methoxy(CH30^*)to formaldehyde(CHO^*)intermediate,a subject of major debate for a long time.The adsorbed formaldehyde(CHO^*)thus produced reacts with another CH30^*species in its close proximity to form the final product of methyl formate.Results of this study provide insights into the reaction mechanism,and offer guidelines to systematically develop and apply photocatalysts for methanol conversion and related reactions via surface engineering.展开更多
Herein,we report on surface plasmon(SP)-sensitive semitransparent inverted polymer photovoltaic(PV)devices that are based on multilayered material systems consisting of poly(3-hexylthiophene):fullerene-derivative bulk...Herein,we report on surface plasmon(SP)-sensitive semitransparent inverted polymer photovoltaic(PV)devices that are based on multilayered material systems consisting of poly(3-hexylthiophene):fullerene-derivative bulk-heterojunction PV layers and thin gold or silver anodes.We demonstrate that these PV devices allow the simultaneous generation of both electrical power and SPs on their anodes for photoexcitation just above the optical absorption edge of the PV layers,resulting not only in attenuated total reflection,but also in attenuated photocurrent generation(APG)under the SP resonance(SPR)condition.Moreover,we also confirm that the biomolecular interaction of biotin–streptavidin on the PV devices can be precisely detected via apparent SPR angle shifts in the APG spectra,even without the need for complex attenuated total reflection configurations.We highlight our view that APG measurements made using these PV devices show great potential for the development of future generations of compact and highly sensitive SPR-based optical sensors.展开更多
Over the past few decades,the metal elements(MEs)in atmospheric particles have aroused great attention.Some well-established techniques have been used to measure particlebound MEs.However,each method has its own advan...Over the past few decades,the metal elements(MEs)in atmospheric particles have aroused great attention.Some well-established techniques have been used to measure particlebound MEs.However,each method has its own advantages and disadvantages in terms of complexity,accuracy,and specific elements of interest.In this study,the performances of inductively coupled plasma-optical emission spectrometry(ICP-OES)and total reflection X-ray fluorescence spectroscopy(TXRF)were evaluated for quality control to analyze data accuracy and precision.The statistic methods(Deming regression and significance testing)were applied for intercomparison between ICP-OES and TXRF measurements for same lowloading PM_(2.5)samples in Weizhou Island.The results from the replicate analysis of standard filters(SRM 2783)and field filters samples indicated that 10 MEs(K,Ca,V,Cr,Mn,Fe,Ni,Cu,Zn,and Pb)showed good accuracies and precision for both techniques.The higher accuracy tended to the higher precision in the MEs analysis process.In addition,the interlab comparisons illustrated that V and Mn all had good agreements between ICP-OES and TXRF.The measurements of K,Cu and Zn were more reliable by TXRF analysis for low-loading PM_(2.5).ICP-OES was more accurate for the determinations for Ca,Cr,Ni and Pb,owing to the overlapping spectral lines and low sensitivity during TXRF analysis.The measurements of Fe,influenced by low-loading PM_(2.5),were not able to determine which instrument could obtain more reliable results.These conclusions could provide reference information to choose suitable instrument for the determination of MEs in low-loading PM_(2.5)samples.展开更多
MicroRNAs(miRNAs),especially exosomal miRNAs,are promising noninvasive biomarkers in early-stage cancer diagnosis and disease treatment monitoring.However,their precise and sensitive quantification remains challenging...MicroRNAs(miRNAs),especially exosomal miRNAs,are promising noninvasive biomarkers in early-stage cancer diagnosis and disease treatment monitoring.However,their precise and sensitive quantification remains challenging due to their small size and low abundance.Herein,we have developed a nanoparticle-confined DNA walker strategy for the specific detection of miRNA.In the existence of the target miRNA;the on-particle DNA walking reaction will be initiated,providing a fluorescence-positive nanoparticle.Otherwise,the nanoparticle would be fluorescence-negative.Utilizing the total internal reflection fluorescent microscope(TIRFM)to digitally count the fluorescence-positive nanoparticles,the proposed method possesses a detection limit of 0.2 pmol/L miRNA and can accurately distinguish the single-base mismatched target.This design combines the merits of the DNA walker for signal amplification and the TIRFM for highly sensitive detection,paving a new way for the digital counting-based analysis of exosomal miRNAs.展开更多
The interferometric particle imaging technique makes use of the angular oscillations of the scattered light in the forward direction for droplet or bubble sizing.The out-of-focus image consists of fringes,the spacing ...The interferometric particle imaging technique makes use of the angular oscillations of the scattered light in the forward direction for droplet or bubble sizing.The out-of-focus image consists of fringes,the spacing of which reflects the interference between the surface-reflected light and the twofold-refracted light.Total internal reflection occurs when the incident light hits the bubble at a large incident angle.The tunneling phase shift is not included in the geometric optics approximation,which leads to a deviation from Mie theory.In this work,we modified the formula for describing the fringe spacing by including the tunneling phase shift of total internal reflection.Numerical analysis and experiments showed that the modification is effective for the measurement of bubbles smaller than 60μm.展开更多
基金supported by the K. C. Wong Education Foundation (GJTD-2018-08)the Natural Science Foundation of China (NSFC) (Grants 11804334, 51705192)+1 种基金the China Postdoctoral Science Foundation (2017M611325)the National Postdoctoral Program for Innovative Talents (BX201600064)
文摘Although abundant research on the anisotropy of van der Waals(vd W)materials has been published,we undertake an in-depth study of their optical properties as they have an important guiding role for light control in two-dimensional(2D)nanospace.As an example,we study the reflectance of few-layered black phosphorus(BP)in the total internal reflection(TIR)mode in detail.We demonstrate that its optical anisotropy can be changed on a large scale by varying the incident angles,polarization states,and the in-plane rotation angles of the BP samples.Theoretical analysis indicates that the phenomena observed are common to all the atom-thick biaxial crystals,so these conclusions can be widely applied to other anisotropic 2D materials.This research furthers the current understanding of the properties of BP more comprehensively,and provides guidance for developing new optoelectronic applications,especially when BP and other atom-thick biaxial crystals are integrated with TIR devices.
基金supported by the National Key Programme of Research and Development,Ministry of Science and Technology(No.2022YFF1301401)the National Natural Science Foundation of China(No.32170428)+2 种基金Research on monitoring technology system of amphibians and reptile in national parks(Research project of the National Park Research Institute)China Biodiversity Observation Networks(Sino BON-Amphibian and Reptile)the Species Conservation Project of Sichuan Liziping National Nature Reserve(2022).
文摘Many animals migrate during the breeding season.It is important to study the patterns of breeding migration of wild animals,especially rare and endangered species.However,current data acquisition methods are too coarse and imprecise for investigating the circadian rhythms of migrations in amphibians.Based on the frustrated total reflection image(FTRI),we developed a new device and recorded the precise migration time of an endangered salamander,Liangshantriton taliangensis.During the breeding period,a total of 33 individuals were effectively recorded.Analysis of the data indicated that the circadian rhythm of breeding migration in L.taliangensis was bimodal,and migration mainly occurred from 05:00 to 13:00(81.82%of the total migration records).The average relative activity intensity index(RAI)of breeding migration peaked in the temperature range of 14.0–16.0°C.With increased average relative air humidity,the activity intensity first increased and then decreased,reaching a peak in the humidity range of 91.0%–97.0%.These results demonstrate that our new device is a viable and accurate method for recording the migration time of target species.It is important to reveal the breeding migration pattern of L.taliangensis,which is important for the conservation of this species.Meanwhile,this new device can be used for field monitoring and conservation studies of amphibians,reptiles and other animals.
文摘For optimization of production processes and product quality,often knowledge of the factors influencing the process outcome is compulsory.Thus,process analytical technology(PAT)that allows deeper insight into the process and results in a mathematical description of the process behavior as a simple function based on the most important process factors can help to achieve higher production efficiency and quality.The present study aims at characterizing a well-known industrial process,the transesterification reaction of rapeseed oil with methanol to produce fatty acid methyl esters(FAME)for usage as biodiesel in a continuous micro reactor set-up.To this end,a design of experiment approach is applied,where the effects of two process factors,the molar ratio and the total flow rate of the reactants,are investigated.The optimized process target response is the FAME mass fraction in the purified nonpolar phase of the product as a measure of reaction yield.The quantification is performed using attenuated total reflection infrared spectroscopy in combination with partial least squares regression.The data retrieved during the conduction of the DoE experimental plan were used for statistical analysis.A non-linear model indicating a synergistic interaction between the studied factors describes the reactor behavior with a high coefficient of determination(R^(2))of 0.9608.Thus,we applied a PAT approach to generate further insight into this established industrial process.
文摘The study of the mineral and organic content of the Allende meteorite is important for our understanding of the molecular evolution of the universe as well as the ancient Earth. Previous studies have characterized the magnetic minerals present in ordinary and carbonaceous chondrites, providing information on the evolution of magnetic fields. The interaction of organic compounds with magnetic minerals is a possible source of chemical diversity, which is crucial for molecular evolution. Carbon compounds in meteorites are of great scientific interest for a variety of reasons, such as their relevance to the origins of chirality in living organisms. This study presents the characterization of organic and mineral compounds in the Allende meteorite. The structural and physicochemical characterization of the Allende meteorite was accomplished through light microscopy, powder X-ray diffraction with complementary Rietveld refinement, Raman and infrared spectroscopy, mass spectrometry, scanning electron microscopy, and atomic force microscopy using magnetic signal methods to determine the complex structure and the interaction of organic compounds with magnetic Ni-Fe minerals. The presence of Liesegang-like patterns of chondrules in fragments of the Allende structure may also be relevant to understanding how the meteorite was formed. Other observations include the presence of magnetic materials and nanorod-like solids with relatively similar sizes as well as the heterogeneous distribution of carbon in chondrules. Signals observed in the Raman and infrared spectra resemble organic compounds such as carbon nanotubes and peptide-like molecules that have been previously reported in other meteorites, making the Mexican Allende meteorite a feasible sample for the study of the early Earth and exoplanetary bodies.
基金the National Natural Science Foundation of China(Grant No.11872033)the Beijing Natural Science Foundation,China(Grant No.3172017).
文摘The spatial and temporal evolution of real contact area of contact interface with loads is a challenge.It is generally believed that there is a positive linear correlation between real contact area and normal load.However,with the development of measuring instruments and methods,some scholars have found that the growth rate of real contact area will slow down with the increase of normal load under certain conditions,such as large-scale interface contact with small roughness surface,which is called the nonlinear phenomenon of real contact area.At present,there is no unified conclusion on the explanation of this phenomenon.We set up an experimental apparatus based on the total reflection principle to verify this phenomenon and analyze its mechanism.An image processing method is proposed,which can be used to quantitative analysis micro contact behaviors on macro contact phenomenon.The weighted superposition method is used to identify micro contact spots,to calculate the real contact area,and the color superimposed image is used to identify micro contact behaviors.Based on this method,the spatiotemporal evolution mechanism of real contact area nonlinear phenomena is quantitatively analyzed.Furthermore,the influence of nonlinear phenomenon of real contact area on the whole loading and unloading process is analyzed experimentally.It is found that the effects of fluid between contact interface,normal load amplitude and initial contact state on contact behavior cannot be ignored in large-scale interface contact with small roughness surface.
基金supported by Takeda Science Foundation,Japanese Foundation for Research and Promotion of Endoscopy,and Grants-in-Aid for Scientific Research(KAKENHI).
文摘Since numerous characteristic absorption lines caused by molecular vibration exist in the midinfrared(MIR)wavelength region,selective excitation or selective dissociation of molecules is possible by tuning the laser wavelength to the characteristic absorption lines of target molecules.By applying this feature to the medical fields,less-invasive treatment and non-destructive diagnosis with absorption spectroscopy are possible using tunable MIR lasers.A high-energy nanosecond pulsed MIR tunable laser was obtained with difference-frequency generation(DFG)between a Nd:YAG and a tunable Cr:forsterite lasers.The MIR-DFG laser was tunable in a wavelength range of 5.5–10μm and generated laser pulses with energy of up to 1.4mJ,a pulse width of 5 ns,and a pulse repetition rate of 10 Hz.Selective removal of atherosclerotic lesion was successfully demonstrated with the MIR-DFG laser tuned at a wavelength of 5.75μm,which corresponds to the characteristic absorption of the ester bond in cholesterol esters in the atherosclerotic lesions.We have developed a non-destructive diagnostic probe with an attenuated total reflection(ATR)prism and two hollow optical fibers.An absorption spectrum of cholesterol was measured with the ATR probe by scanning the wavelength of the MIR-DFG laser,and the spectrum was in good agreement with that measured with a commercial Fourier transform infrared spectrometer.
文摘This work describes synthesis of graphene sheets with modified surface by sodium lauryl sulfate (SLS) surfactant using one-pot solvothermal reaction method. Effect of sodium lauryl sulfate surfactant amount on surface modification level of graphene sheets was investigated. Ether (-S-OR- at 762 cm<sup>-1</sup> - 863 cm<sup>-1</sup>), thiocarbonyl (=C=S at 1050 cm<sup>-1</sup> - 1176 cm<sup>-1</sup>) and sulfoxide (S-O, V<sub>s</sub> and V<sub>as</sub> at 1030 cm<sup>-1</sup> - 1450 cm<sup>-1</sup>) functional groups released from sodium lauryl sulfate (SLS) surfactant during solvothermal reaction and attached on the surface of graphene sheets were detected by (attenuated total reflectance-fast Fourier infrared) ATR-FTIR spectroscopy. (Atomic force microscope) AFM observations revealed apparent surface of graphene sheets modified by surfactant molecules with an average multiple profile of graphene nanosheets ≈ 4.8 nm high. This synthesis way of surface modified graphene sheets can be considered as easy, one-step and cheap method for manufacturing of novel biosurface with graphene, as reinforcement for biopolymer coatings such as ultra-high molecular weight polypropylene (UHMWPE), metallic biomaterials (Ti and Ti alloys) and bioceramics as hydroxyapatite (HA).
文摘Raman spectroscopy is a common method of studying carbon-based materials such as multi-walled carbon nanotubes (MWCNT). However, the analysis of this technique is non-trivial since recorded spectra may be a convolution of both molecular vibrations and phonon resonances. The energies of these physical processes may occur in the same energy regime, and hence several analytical approaches can be necessary for a full analysis. Due to the negligible quantities of non-graphitic carbon in MWCNT, the present fitting procedure focuses on understanding phonon resonances to elucidate how varying modifications of MWCNT ultimately influence their graphitic bulk structure. We have found this approach to provide greater insight into the structure of MWCNT when low quantities of amorphous carbon are present, when compared with methods which try to interpret both phonon scattering and molecular vibrations simultaneously. Different pre-treatments for the modification of the graphitic structure of MWCNT are compared, including aqueous acidic and gas phase methods, and statistically evaluated. Focusing on phonon resonances enables one to analyze the reaction process of nitrosulfuric acid pre-treatment at different temperatures. Thereby, it is possible to control the ratio between defects and graphitic structures in MWCNT samples and prepare samples with reproducible D/G ratios.
基金National Natural Science Foundation of China(NSFC)(11274106,11474089)
文摘In this paper,we examine the tiny polarization rotation effect in total internal reflection due to the spin–orbit interaction of light.We find that the tiny polarization rotation rate will induce a geometric phase gradient,which can be regarded as the physical origin of photonic spin Hall effect.We demonstrate that the spin-dependent splitting in position space is related to the polarization rotation in momentum space,while the spin-dependent splitting in momentum space is attributed to the polarization rotation in position space.Furthermore,we introduce a quantum weak measurement to determine the tiny polarization rotation rate.The rotation rate in momentum space is obtained with 118 nm,which manifests itself as a spatial shift,and the rotation rate in position space is achieved with 38 μrad∕λ,which manifests itself as an angular shift.The investigation of the polarization rotation characteristics will provide insights into the photonic spin Hall effect and will enable us to better understand the spin–orbit interaction of light.
基金This work has been supported by project 60177012 of National Natural Science Foundation of China and project G1999033104 of Major State Basic Research Development Program in China.
文摘Y-branching TIR all-optical switch have been fabricated. When the switching optical intensity is 149.9W/mm2, the extinction ratio is 18dB. A theoretical model was also proposed which provided a good fit to the experimental data.
基金support from National Basic Research Program of China (973 Program) (2015CB352005)National Natural Science Foundation of China (No.6142780065,31571110,81527901)+1 种基金Natural Science Foundation of Zhejiang Province of China (No.Y16F050002)the Fundamental Research Funds for the Central Universities.
文摘Optical microscopy promises researchers to soe most tiny substances directly.However,the resolution of conventional microscopy is resticted by the diffraction limit.This makes it a challenge to observe subcellular processes happened in nanoscale.The development of super-resolution microscopy provides a solution to this challenge.Here,we briefly review several commonly used super-resolution techniques,explicating their basic principles and applications in biological science,especially in neuroscience.In addition,characteristics and limitations of each techrique are compared to provide a guidance for biologists to choose the most suitable tool.
文摘Adhesion molecule CD146 (100-130kDa) belongs to the immunoglobulin super family and it is originally identified as a biomarker for melanoma. Recently, CD146 is found as
文摘Design of ultra-wideband antennas is challenging in the stringent requirements that are often conflicting to achieve a wide impedance bandwidth while maintaining high radiation efficiency, uniform gain and compact size. A Multiple-Input Multiple-Output (MIMO) antenna system can enhance the overall antenna performance but at having to overcome new challenges such as reducing the mutual coupling and the correlation between the elements. A printed circular disc compact planar antenna is selected in this work due to its UWB performance and compact size for the MIMO antenna system. A parametric analysis is carried out to achieve an optimal design. The system developed consists of two elements with an overall size of 59 × 27 mm. The designed antenna system operates over the whole of the UWB bandwidth from 3.1 to 10.6 GHz with radiation efficiency up to 85% and reflection coefficients less that ?10 dB. The envelope correlation is less than ?60 dB throughout the UWB band while the diversity gain approaches 10 throughout the entire UWB bandwidth and Total Active Reflection Coefficient (TARC) between the antenna elements is less ?11 dB. Thus the proposed MIMO antenna outperforms similar antenna systems reported in the literature.
基金supported by the National Natural Science Foundation of China(Nos.22003074 and 22002087)Youth Innovation Promotion Association CAS,Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials(No.2021MCIMKF03)Baoshan Iron&Steel Co.,Ltd.(Baosteel),located in Shanghai,China.
文摘Through interface engineering and content control strategy,a PdBi bimetallic interface structure was constructed for the first time to selectively convert CO_(2)to formate with a remarkably high Faraday efficiency(FEformate)of 94%and a partial current density(jformate)of 34 mA·cm^(−2)at−0.8 V vs.reversible hydrogen electrode(RHE)in an H-cell.Moreover,the PdBi interface electrocatalyst even exhibited a high current density of 180 mA·cm^(−2)with formate selectivity up to 92%in a flow cell and could steadily operate for at least 20 h.Electrochemical in-situ attenuated total reflection surface enhanced infrared absorption spectroscopy(ATR-SEIRAS)confirmed that the PdBi interface could greatly weaken the adsorption of*CO intermediates due to electronic and geometric effects.Density functional theory(DFT)calculations also established that the PdBi interface regulated the CO_(2)-to-formate pathway by reducing the energy barrier toward HCOOH and largely weakening the adsorption of*CO intermediates on the catalyst surface.This study reveals that the unique PdBi bimetallic interface can provide a novel platform to study the reaction mechanism through combining in-situ ATR-SEIRAS and DFT calculations.
基金supported by the National Natural Science Foundation of China (Nos. 22074088, 21622507, 21904083)the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT_15R43)+1 种基金the Innovation Capability Support Program of Shaanxi (No. 2021TD-42)the Fundamental Research Funds for the Central Universities (Nos. GK202101001 and GK202201009)。
文摘T4 polynucleotide kinase(T4 PNK) is a pivotal enzyme for DNA replication, recombination, and DNA damage repair. Herein, a robust single particle counting-based assay has been developed for the high-sensitive determination of T4 PNK activity through only a simple one-step reaction. Taking benefit of the exceptional space-confined enzymatic property of T4 PNK towards DNA substrates on a single nanoparticle,the T4 PNK activity can be precisely determined by counting the fluorescence-positive nanoparticles in a digital manner with a total internal reflection fluorescent microscope(TIRFM). Due to the featured spatial-confined enzymatic property of T4 PNK and the single particle counting-based signal readout, T4PNK can be effectively differentiated from other interfering enzymes. This facile strategy has been also successfully applied to screen T4 PNK inhibitor and accurately determine T4 PNK activity in complex biological samples, paving a potential avenue for the digital analysis of biomarkers.
基金Q.Q.S.thanks the Postdoctoral Science Foundation of China(No.223232),the Natural Science Foundation of Inner Mongolia Autonomous Region(No.2018BS02004)the major special topics of Inner Mongolia science and technology department(No.20181351)+3 种基金Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(No.NJYT-20-B20)the Program of Higher-level Talents of Inner Mongolia Agricultural University(No.NDYB2016-03)LiaoNing Revitalization Talents Program(No.XLYC1807121)Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2019)for financial support.
文摘We report experimental and mechanistic understanding of methanol oxidation to produce methyl formate using CuO/Ti02-spindle composite as a promising photocatalyst under mild conditions with over 97%conversion and 83%selectivity.The catalysts are obtained via precise depositing of CuO nanoclusters(size:~3.5 nm)at the{101}facet of the TiO2 to optimally tune exciton recombination through oxygen vacancies generation,evidenced by photoluminescence and Raman spectroscopy measurements.The turnover frequency(TOF)and the apparent quantum efficiency(AQE)of the 7%CuO/TiO2-spindle composites reach up to 23.8 molmethanol·gcat^-1·h^-1 and 55.2%at 25℃,respectively,which are substantially higher than these previously reported photocatalysts.Further,the in-situ attenuated total reflection infrared spectroscopy analysis reveals that the methanol oxidation most likely takes place through the conversion of adsorbed methoxy(CH30^*)to formaldehyde(CHO^*)intermediate,a subject of major debate for a long time.The adsorbed formaldehyde(CHO^*)thus produced reacts with another CH30^*species in its close proximity to form the final product of methyl formate.Results of this study provide insights into the reaction mechanism,and offer guidelines to systematically develop and apply photocatalysts for methanol conversion and related reactions via surface engineering.
基金The authors thank H Takezoe for his careful reading and helpful comments on this paper.This work was supported by the Basic Science Research Program through National Research Foundations of Korea(NRF)Grant funded by the Korea Government(MSIP)(NRF-2010-0027963,2012R1A2A2A01015654 and 2014R1A2A1A10054643)by Kwangwoon University(2014)The authors also thank GC Kwon,JH Shin and J Choi for their helpful comments.
文摘Herein,we report on surface plasmon(SP)-sensitive semitransparent inverted polymer photovoltaic(PV)devices that are based on multilayered material systems consisting of poly(3-hexylthiophene):fullerene-derivative bulk-heterojunction PV layers and thin gold or silver anodes.We demonstrate that these PV devices allow the simultaneous generation of both electrical power and SPs on their anodes for photoexcitation just above the optical absorption edge of the PV layers,resulting not only in attenuated total reflection,but also in attenuated photocurrent generation(APG)under the SP resonance(SPR)condition.Moreover,we also confirm that the biomolecular interaction of biotin–streptavidin on the PV devices can be precisely detected via apparent SPR angle shifts in the APG spectra,even without the need for complex attenuated total reflection configurations.We highlight our view that APG measurements made using these PV devices show great potential for the development of future generations of compact and highly sensitive SPR-based optical sensors.
基金supported by the National Natural Science Foundation of China(No.42075182)the Science and Technology Pre-research Project for Collaborative Prevention and Control on O3 and PM2.5 Compound Pollution(No.DQGG202026)the Three-dimensional Comprehensive Observation Research Program for O3and PM2.5Compound Pollution in Key Areas in Summer 2021(No.DQGG2021101)
文摘Over the past few decades,the metal elements(MEs)in atmospheric particles have aroused great attention.Some well-established techniques have been used to measure particlebound MEs.However,each method has its own advantages and disadvantages in terms of complexity,accuracy,and specific elements of interest.In this study,the performances of inductively coupled plasma-optical emission spectrometry(ICP-OES)and total reflection X-ray fluorescence spectroscopy(TXRF)were evaluated for quality control to analyze data accuracy and precision.The statistic methods(Deming regression and significance testing)were applied for intercomparison between ICP-OES and TXRF measurements for same lowloading PM_(2.5)samples in Weizhou Island.The results from the replicate analysis of standard filters(SRM 2783)and field filters samples indicated that 10 MEs(K,Ca,V,Cr,Mn,Fe,Ni,Cu,Zn,and Pb)showed good accuracies and precision for both techniques.The higher accuracy tended to the higher precision in the MEs analysis process.In addition,the interlab comparisons illustrated that V and Mn all had good agreements between ICP-OES and TXRF.The measurements of K,Cu and Zn were more reliable by TXRF analysis for low-loading PM_(2.5).ICP-OES was more accurate for the determinations for Ca,Cr,Ni and Pb,owing to the overlapping spectral lines and low sensitivity during TXRF analysis.The measurements of Fe,influenced by low-loading PM_(2.5),were not able to determine which instrument could obtain more reliable results.These conclusions could provide reference information to choose suitable instrument for the determination of MEs in low-loading PM_(2.5)samples.
基金the National Natural Science Foundation of China(Nos.22074088 and 21904083)the Program for Changjiang Scholars and Innovative Research Team in University(IRT_15R43)the Fundamental Research Funds for the Central Universities(Nos.GK202003038,GK201901003,2020TS089,GK202101001).
文摘MicroRNAs(miRNAs),especially exosomal miRNAs,are promising noninvasive biomarkers in early-stage cancer diagnosis and disease treatment monitoring.However,their precise and sensitive quantification remains challenging due to their small size and low abundance.Herein,we have developed a nanoparticle-confined DNA walker strategy for the specific detection of miRNA.In the existence of the target miRNA;the on-particle DNA walking reaction will be initiated,providing a fluorescence-positive nanoparticle.Otherwise,the nanoparticle would be fluorescence-negative.Utilizing the total internal reflection fluorescent microscope(TIRFM)to digitally count the fluorescence-positive nanoparticles,the proposed method possesses a detection limit of 0.2 pmol/L miRNA and can accurately distinguish the single-base mismatched target.This design combines the merits of the DNA walker for signal amplification and the TIRFM for highly sensitive detection,paving a new way for the digital counting-based analysis of exosomal miRNAs.
基金The work was supported by National Science and Technology Major Project of China(2017-V-0016-0069).
文摘The interferometric particle imaging technique makes use of the angular oscillations of the scattered light in the forward direction for droplet or bubble sizing.The out-of-focus image consists of fringes,the spacing of which reflects the interference between the surface-reflected light and the twofold-refracted light.Total internal reflection occurs when the incident light hits the bubble at a large incident angle.The tunneling phase shift is not included in the geometric optics approximation,which leads to a deviation from Mie theory.In this work,we modified the formula for describing the fringe spacing by including the tunneling phase shift of total internal reflection.Numerical analysis and experiments showed that the modification is effective for the measurement of bubbles smaller than 60μm.