2018 Volume 34 Issue 1
2018, 34(1):
Abstract:
Confined Catalysis under Two-Dimensional Materials and Its Modulation on Surface Catalytic Reactions
2018, 34(1): 1-2
doi: 10.3866/PKU.WHXB201706291
Abstract:
2018, 34(1): 3-4
doi: 10.3866/PKU.WHXB201706281
Abstract:
2018, 34(1): 7-8
doi: 10.3866/PKU.WHXB201707051
Abstract:
2018, 34(1): 9-10
doi: 10.3866/PKU.WHXB201707072
Abstract:
2018, 34(1): 11-21
doi: 10.3866/PKU.WHXB201706301
Abstract:
Owing to the unique physical, chemical, optical, and biological properties, plasmonic nanoparticles (PNPs) have been widely used in various research fields such as materials science, biology, and medicine. The optical properties of PNPs can be regulated by changing their composition, shape, and size, so that a suitable light-scattering probe can be screened by means of controllable synthesis. Real-time study of the dynamic behavior of PNPs at the single molecule level is of great significance for understanding the biological behaviors of living cells and tissues, fabricating functional nanomaterials, and developing new chemical biosensors. Starting from the traditional dark-field microscopy (DFM), we have developed a series of plasmonic light-scattering imaging techniques with high sensitivity, high temporal-spatial resolution, and high throughput through optimizing the assembly of light sources, detectors, and other optical components, and applied these techniques to single molecule detection, multi-particle sensing, single cell imaging, biological process tracing, and so on. Based on the PNPs with optical anisotropy, we have also developed a three-dimensional scanning imaging system for living cells and asupercontinuum laser light-sheet imaging system coupled with high-speed capillary electrophoresis system, advancing the study of single molecule spectroscopy. This paper will summarize the work on PNP single particle analysis and imaging in our research group during the past ten years, and put forward some new ideas for further development in this field.
Owing to the unique physical, chemical, optical, and biological properties, plasmonic nanoparticles (PNPs) have been widely used in various research fields such as materials science, biology, and medicine. The optical properties of PNPs can be regulated by changing their composition, shape, and size, so that a suitable light-scattering probe can be screened by means of controllable synthesis. Real-time study of the dynamic behavior of PNPs at the single molecule level is of great significance for understanding the biological behaviors of living cells and tissues, fabricating functional nanomaterials, and developing new chemical biosensors. Starting from the traditional dark-field microscopy (DFM), we have developed a series of plasmonic light-scattering imaging techniques with high sensitivity, high temporal-spatial resolution, and high throughput through optimizing the assembly of light sources, detectors, and other optical components, and applied these techniques to single molecule detection, multi-particle sensing, single cell imaging, biological process tracing, and so on. Based on the PNPs with optical anisotropy, we have also developed a three-dimensional scanning imaging system for living cells and asupercontinuum laser light-sheet imaging system coupled with high-speed capillary electrophoresis system, advancing the study of single molecule spectroscopy. This paper will summarize the work on PNP single particle analysis and imaging in our research group during the past ten years, and put forward some new ideas for further development in this field.
2018, 34(1): 22-35
doi: 10.3866/PKU.WHXB201706302
Abstract:
Functional materials and devices that can efficiently store and convert energies have attracted a great deal of attention in recent years. The composites of layered double hydroxide and graphene (LDH/G) are important energy materials. They have excellent physical and chemical properties of both components. Furthermore, their performances in energy-related systems can be improved by increasing the electrical conductivity of LDHs by blending graphene and partly preventing the aggregation of graphene sheets using LDH nanostructures. Therefore, LDH/G composites can be used in various energy applications, particularly for developing high-performance supercapacitors and efficient electrocatalysts for electrochemical splitting of water. In this review, we summarize the recent advances on the synthesis of LDH/chemically modified graphene (CMG, e.g., graphene oxide, reduced graphene oxide and their derivatives) composites and their application in electrochemical energy storage and conversion. Furthermore, the challenges and future perspectives in this research field are also outlined.
Functional materials and devices that can efficiently store and convert energies have attracted a great deal of attention in recent years. The composites of layered double hydroxide and graphene (LDH/G) are important energy materials. They have excellent physical and chemical properties of both components. Furthermore, their performances in energy-related systems can be improved by increasing the electrical conductivity of LDHs by blending graphene and partly preventing the aggregation of graphene sheets using LDH nanostructures. Therefore, LDH/G composites can be used in various energy applications, particularly for developing high-performance supercapacitors and efficient electrocatalysts for electrochemical splitting of water. In this review, we summarize the recent advances on the synthesis of LDH/chemically modified graphene (CMG, e.g., graphene oxide, reduced graphene oxide and their derivatives) composites and their application in electrochemical energy storage and conversion. Furthermore, the challenges and future perspectives in this research field are also outlined.
2018, 34(1): 36-48
doi: 10.3866/PKU.WHXB201706304
Abstract:
ZnO has attracted extensive research in perovskite solar cells because of its high electron mobility, spectacular optical transparency, low-temperature processing, and ease of synthesis. Traditional electrode buffer layers used in perovskite solar cells have shown some drawbacks, such as high-temperature treatment, low transmittance, and complex fabrication procedures, which might not be fit for the further development of high-performance flexible perovskite solar cells. Here, we intend to give a systematic introduction to the fabrication and functions of ZnO electrode buffer layers (sol-gel method, pre-fabricated ZnO nanoparticle suspension, atomic layer deposition, spray pyrolysis, electrodeposition, chemical bath deposition, radio-frequency sputtering, metal organic chemical vapor deposition, and magnetron sputtering etc.). Particular attentions were paid to the understanding of the structure-property relations between the thickness, morphology, doping, and composition of ZnO electrode buffer layers and the performance of perovskite solar cells (open circuit voltage, current density, fill factor, power conversion efficiency, etc.). A perspective on the future development of ZnO electrode buffer layers and their applications in perovskite solar cells were also discussed in this review.
ZnO has attracted extensive research in perovskite solar cells because of its high electron mobility, spectacular optical transparency, low-temperature processing, and ease of synthesis. Traditional electrode buffer layers used in perovskite solar cells have shown some drawbacks, such as high-temperature treatment, low transmittance, and complex fabrication procedures, which might not be fit for the further development of high-performance flexible perovskite solar cells. Here, we intend to give a systematic introduction to the fabrication and functions of ZnO electrode buffer layers (sol-gel method, pre-fabricated ZnO nanoparticle suspension, atomic layer deposition, spray pyrolysis, electrodeposition, chemical bath deposition, radio-frequency sputtering, metal organic chemical vapor deposition, and magnetron sputtering etc.). Particular attentions were paid to the understanding of the structure-property relations between the thickness, morphology, doping, and composition of ZnO electrode buffer layers and the performance of perovskite solar cells (open circuit voltage, current density, fill factor, power conversion efficiency, etc.). A perspective on the future development of ZnO electrode buffer layers and their applications in perovskite solar cells were also discussed in this review.
2018, 34(1): 49-64
doi: 10.3866/PKU.WHXB201707041
Abstract:
Magnetic nanoparticles (MNPs) have attracted great attention because of their unique physiochemical properties in emulsion preparation and demulsification.This paper summarizes the synthesis,structure,and significant properties of functional magnetic nanoparticles.The application of MNPs in emulsion preparation and demulsification is also reviewed.The processes through which MNPs disperse well in liquid and stably absorb on the oil-water interface leading to the formation of films are emphatically analyzed.More importantly,their magnetic response contributed to the change in interface properties,deformation,and migration of magnetically responsive droplets in the emulsion issummarized.Then,we summarize the effects of surface properties and behaviors of MNPs on emulsion stabilization or demulsification.This study provides a theoretical support for further applications of emulsions.Finally,we propose the crucial issues to be addressed in studying the application and effect of functional magnetic nanoparticles.
Magnetic nanoparticles (MNPs) have attracted great attention because of their unique physiochemical properties in emulsion preparation and demulsification.This paper summarizes the synthesis,structure,and significant properties of functional magnetic nanoparticles.The application of MNPs in emulsion preparation and demulsification is also reviewed.The processes through which MNPs disperse well in liquid and stably absorb on the oil-water interface leading to the formation of films are emphatically analyzed.More importantly,their magnetic response contributed to the change in interface properties,deformation,and migration of magnetically responsive droplets in the emulsion issummarized.Then,we summarize the effects of surface properties and behaviors of MNPs on emulsion stabilization or demulsification.This study provides a theoretical support for further applications of emulsions.Finally,we propose the crucial issues to be addressed in studying the application and effect of functional magnetic nanoparticles.
2018, 34(1): 65-72
doi: 10.3866/PKU.WHXB201706233
Abstract:
Fundamental data of liquid-liquid equilibria (LLE) are important in the design and development of extraction processes. In order to obtain such data for the extraction of cyclohexanone from wastewater using methyl isobutyl ketone (MIBK) as a solvent, the MIBK-cyclohexanone-water ternary system was studied at 303.15, 313.15, and 323.15 K under atmospheric pressure. The distribution coefficient and separation factors for this system were calculated and it was found that all separation factors were much larger than one, which demonstrated the feasibility of using MIBK as a solvent to treat the cyclohexanone-containing wastewater. Additionally, the Hand and Bachman equations were both used to check the reliability and consistency of the obtained experimental data. The squares of the linear correlation coefficients were determined to be greater than 0.99, indicating excellent agreement. The NRTL and the UNIQUAC activity coefficient models were also employed to correlate the experimental results obtained for this ternary system. The root mean square deviation (RMSD) values of the two models were evaluated to be less than 0.50%. Furthermore, the binary interaction parameters of the ternary system were also obtained
Fundamental data of liquid-liquid equilibria (LLE) are important in the design and development of extraction processes. In order to obtain such data for the extraction of cyclohexanone from wastewater using methyl isobutyl ketone (MIBK) as a solvent, the MIBK-cyclohexanone-water ternary system was studied at 303.15, 313.15, and 323.15 K under atmospheric pressure. The distribution coefficient and separation factors for this system were calculated and it was found that all separation factors were much larger than one, which demonstrated the feasibility of using MIBK as a solvent to treat the cyclohexanone-containing wastewater. Additionally, the Hand and Bachman equations were both used to check the reliability and consistency of the obtained experimental data. The squares of the linear correlation coefficients were determined to be greater than 0.99, indicating excellent agreement. The NRTL and the UNIQUAC activity coefficient models were also employed to correlate the experimental results obtained for this ternary system. The root mean square deviation (RMSD) values of the two models were evaluated to be less than 0.50%. Furthermore, the binary interaction parameters of the ternary system were also obtained
Microcalorimetric Analysis of Isolated Rat Liver Mitochondrial Metabolism under Different Conditions
2018, 34(1): 73-80
doi: 10.3866/PKU.WHXB201707043
Abstract:
Isolated rat liver mitochondria were proposed as a model to monitor real-time heat metabolism.A high-throughput and sensitive thermal activity monitor III (TAM III) was used to detect the P-t curves of mitochondria under different conditions,including different mitochondrial concentrations,different substrates,different buffers,respiratory inhibitors,Ca2+,and CsA.We determined the thermokinetic parameters through calculation.The results showed that:(1) higher concentration of mitochondria led to faster energetic metabolism;(2) when succinate was the direct respiratory substrate,it promoted mitochondrial metabolism,in contrast to the condition when an indirect substrate,pyruvate,was used;(3) high concentration of Ca2+(2.5 mmol·L-1) stimulated mitochondrial metabolism,however CsA,an inhibitor of mitochondrial permeability transition pores,could not reverse the Ca2+-induced mitochondrial alteration;(4) mitochondria in various buffers displayed different rates of heat metabolism,because of the different composition of the buffers;(5) mitochondrial metabolism was inhibited by respiratory inhibitors,especially NaN3,which is an inhibitor of Complex IV and which completely stopped the mitochondrial heat release.
Isolated rat liver mitochondria were proposed as a model to monitor real-time heat metabolism.A high-throughput and sensitive thermal activity monitor III (TAM III) was used to detect the P-t curves of mitochondria under different conditions,including different mitochondrial concentrations,different substrates,different buffers,respiratory inhibitors,Ca2+,and CsA.We determined the thermokinetic parameters through calculation.The results showed that:(1) higher concentration of mitochondria led to faster energetic metabolism;(2) when succinate was the direct respiratory substrate,it promoted mitochondrial metabolism,in contrast to the condition when an indirect substrate,pyruvate,was used;(3) high concentration of Ca2+(2.5 mmol·L-1) stimulated mitochondrial metabolism,however CsA,an inhibitor of mitochondrial permeability transition pores,could not reverse the Ca2+-induced mitochondrial alteration;(4) mitochondria in various buffers displayed different rates of heat metabolism,because of the different composition of the buffers;(5) mitochondrial metabolism was inhibited by respiratory inhibitors,especially NaN3,which is an inhibitor of Complex IV and which completely stopped the mitochondrial heat release.
2018, 34(1): 81-91
doi: 10.3866/PKU.WHXB201706303
Abstract:
Multi-scale quantum-mechanical/molecular-mechanical (QM/MM) and large-scale QM simulation provide valuable insight into enzyme mechanism and structure-property relationships. Analysis of the electron density afforded through these methods can enhance our understanding of how the enzyme environment modulates reactivity at the enzyme active site. From this perspective, tools from conceptual density functional theory to interrogate electron densities can provide added insight into enzyme function. We recently introduced the highly parallelizable Fukui shift analysis (FSA) method, which identifies how frontier states of an active site are altered by the presence of an additional QM residue to identify when QM treatment of a residue is essential as a result of quantum-mechanically affecting the behavior of the active site. We now demonstrate and analyze distance and residue dependence of Fukui function shifts in pairs of residues representing different non-covalent interactions. We also show how the interpretation of the Fukui function as a measure of relative nucleophilicity provides insight into enzymes that carry out SN2 methyl transfer. The FSA method represents a promising approach for the systematic, unbiased determination of quantum mechanical effects in enzymes and for other complex systems that necessitate multi-scale modeling.
Multi-scale quantum-mechanical/molecular-mechanical (QM/MM) and large-scale QM simulation provide valuable insight into enzyme mechanism and structure-property relationships. Analysis of the electron density afforded through these methods can enhance our understanding of how the enzyme environment modulates reactivity at the enzyme active site. From this perspective, tools from conceptual density functional theory to interrogate electron densities can provide added insight into enzyme function. We recently introduced the highly parallelizable Fukui shift analysis (FSA) method, which identifies how frontier states of an active site are altered by the presence of an additional QM residue to identify when QM treatment of a residue is essential as a result of quantum-mechanically affecting the behavior of the active site. We now demonstrate and analyze distance and residue dependence of Fukui function shifts in pairs of residues representing different non-covalent interactions. We also show how the interpretation of the Fukui function as a measure of relative nucleophilicity provides insight into enzymes that carry out SN2 methyl transfer. The FSA method represents a promising approach for the systematic, unbiased determination of quantum mechanical effects in enzymes and for other complex systems that necessitate multi-scale modeling.
2018, 34(1): 92-98
doi: 10.3866/PKU.WHXB201706221
Abstract:
In order to explore their luminescence properties,a series of carbon nanodots were prepared by microwave heating by controlling the microwave power,reaction time,and pH value.The luminescence properties of carbon nanodots were characterized by their fluorescence excitation spectrum and emission spectrum.We present the transformation mechanism of glucose into carbon nanodots during the microwave heating process and the corresponding luminescence mechanism together with the analysis of functional group changes during the reaction as monitored with ultraviolet (UV) absorption and Fourier Transform Infrared (FT-IR) spectra.The results show that the optimal luminescence properties of carbon nanodots were obtained when the glucose was heated under a microwave heating power of 560 W for 2.5 min.When the carbon nanodots were excited with UV radiation with a wavelength of 370 nm,the strongest luminescence appeared at 451 nm.The wavelength of the strongest luminescence peak moved from 350 nm to higher wavelengths significantly,when the pH value was modified from acidic to alkaline,and was accompanied with a significant rise in luminescence peak intensity.We show that polycyclic aromatic hydrocarbons form in the reaction process,as evidenced by UV absorption and FTIR monitoring,indicating that microwave synthesis of carbon nanodots proceeds via polymerization and final carbonization of glucose.Carbon nanodots formed under different pH values exhibit a change in the ratio of carbon-to-carbon double bonds to carbon-to-oxygen double bonds.The optical bandgap and exciton binding energy of the carbon nanodots were also investigated comprehensively.
In order to explore their luminescence properties,a series of carbon nanodots were prepared by microwave heating by controlling the microwave power,reaction time,and pH value.The luminescence properties of carbon nanodots were characterized by their fluorescence excitation spectrum and emission spectrum.We present the transformation mechanism of glucose into carbon nanodots during the microwave heating process and the corresponding luminescence mechanism together with the analysis of functional group changes during the reaction as monitored with ultraviolet (UV) absorption and Fourier Transform Infrared (FT-IR) spectra.The results show that the optimal luminescence properties of carbon nanodots were obtained when the glucose was heated under a microwave heating power of 560 W for 2.5 min.When the carbon nanodots were excited with UV radiation with a wavelength of 370 nm,the strongest luminescence appeared at 451 nm.The wavelength of the strongest luminescence peak moved from 350 nm to higher wavelengths significantly,when the pH value was modified from acidic to alkaline,and was accompanied with a significant rise in luminescence peak intensity.We show that polycyclic aromatic hydrocarbons form in the reaction process,as evidenced by UV absorption and FTIR monitoring,indicating that microwave synthesis of carbon nanodots proceeds via polymerization and final carbonization of glucose.Carbon nanodots formed under different pH values exhibit a change in the ratio of carbon-to-carbon double bonds to carbon-to-oxygen double bonds.The optical bandgap and exciton binding energy of the carbon nanodots were also investigated comprehensively.
2018, 34(1): 99-107
doi: 10.3866/PKU.WHXB201706262
Abstract:
Multiwalled carbon nanotubes modified on the surface by imidazole ionic liquids with different types of anions (Br-,BF4-,PF6- or H2PO4-) as a new-generation carrier were fabricated.Subsequently,Candida antarctic lipase B (CALB) was immobilized on the functionalized MWNTs via physical attachment,and its enzymology properties were tested.The morphology of the MWNTs before and after the modification was determined by transmission electron microscopy (TEM),Raman spectroscopy,thermo gravimetric analysis (TGA),and X-ray photoelectron spectroscopy (XPS).These characterizations were used to study the influence of surface modification of materials on the enzymatic properties.The results revealed that CALB immobilized on MWNTs modified by ionic liquids not only had a higher specific activity as compared with that of CALB immobilized on pure MWNTs,but also better tolerance (high temperature,high pH),thermostability,and reusability.The different anions of ionic liquids,which were used to modify MWNTs,exert a remarkable effect on the properties of immobilized enzyme.The specific activity of MWNTs-IL (PF6-)-CALB were the highest and were five times higher than that of MWNTs-CALB with no modification.The analysis of kinetic parameters of immobilized enzymes showed that the modification of ionic liquids for carriers enhanced the affinity between the enzyme and the substrate,so as to increase the enzyme activity.
Multiwalled carbon nanotubes modified on the surface by imidazole ionic liquids with different types of anions (Br-,BF4-,PF6- or H2PO4-) as a new-generation carrier were fabricated.Subsequently,Candida antarctic lipase B (CALB) was immobilized on the functionalized MWNTs via physical attachment,and its enzymology properties were tested.The morphology of the MWNTs before and after the modification was determined by transmission electron microscopy (TEM),Raman spectroscopy,thermo gravimetric analysis (TGA),and X-ray photoelectron spectroscopy (XPS).These characterizations were used to study the influence of surface modification of materials on the enzymatic properties.The results revealed that CALB immobilized on MWNTs modified by ionic liquids not only had a higher specific activity as compared with that of CALB immobilized on pure MWNTs,but also better tolerance (high temperature,high pH),thermostability,and reusability.The different anions of ionic liquids,which were used to modify MWNTs,exert a remarkable effect on the properties of immobilized enzyme.The specific activity of MWNTs-IL (PF6-)-CALB were the highest and were five times higher than that of MWNTs-CALB with no modification.The analysis of kinetic parameters of immobilized enzymes showed that the modification of ionic liquids for carriers enhanced the affinity between the enzyme and the substrate,so as to increase the enzyme activity.
2018, 34(1): 108-112
doi: 10.3866/PKU.WHXB201710125
Abstract: