2007 Vol. 36 No. 06
2007, 36(06): 419-426.
Abstract：
Previous studies on the activity of bio-molecules in a cell were mostly performed on the basis of ensemble averaging. However, with the advent of new technology, especially optical and fluorescence techniques, it is now possible to visualize the dynamics and kinetics of a single bio-molecule in the living cell in real time. From the methodological aspect, many techniques are now available: fluorescent resonance energy transfer, atomic force microscopy, total internal reflection fluorescence, fluorescence correlation microscopy, and so forth. The investigation of single molecule behavior will probably open a new horizon in the future biological study. However, still many technical limitations existed, for example, the lack of small molecule fluorescent probes and new types of microscope with higher resolution beyond diffraction barrier, the difficulties in visualizing small fluorescent spot in the cell interior.
Previous studies on the activity of bio-molecules in a cell were mostly performed on the basis of ensemble averaging. However, with the advent of new technology, especially optical and fluorescence techniques, it is now possible to visualize the dynamics and kinetics of a single bio-molecule in the living cell in real time. From the methodological aspect, many techniques are now available: fluorescent resonance energy transfer, atomic force microscopy, total internal reflection fluorescence, fluorescence correlation microscopy, and so forth. The investigation of single molecule behavior will probably open a new horizon in the future biological study. However, still many technical limitations existed, for example, the lack of small molecule fluorescent probes and new types of microscope with higher resolution beyond diffraction barrier, the difficulties in visualizing small fluorescent spot in the cell interior.
2007, 36(06): 427-429.
Abstract：
A key element of functionalizing nanocrystals with organic molecules is the nontemplated selective adsorption of different molecules on different facets. Here we report scanning-tunneling-microscopy images of perylene-3,4,9,10-tetracarboxylic-dianhydride and 2,5-dimethyl-N,N′-dicyanoquinonediimine on silver, demonstrating selective adsorption on different facets. We also report first-principles calculations that account for the data and show that bonding, which controls selectivity, occurs via the end atoms, while the molecule's midregion arches away from the substrate. The results are also consistent with data that have been interpreted in terms of bonding via the midregion.
A key element of functionalizing nanocrystals with organic molecules is the nontemplated selective adsorption of different molecules on different facets. Here we report scanning-tunneling-microscopy images of perylene-3,4,9,10-tetracarboxylic-dianhydride and 2,5-dimethyl-N,N′-dicyanoquinonediimine on silver, demonstrating selective adsorption on different facets. We also report first-principles calculations that account for the data and show that bonding, which controls selectivity, occurs via the end atoms, while the molecule's midregion arches away from the substrate. The results are also consistent with data that have been interpreted in terms of bonding via the midregion.
2007, 36(06): 430-433.
Abstract：
We briefly review current research on strongly interacting ultracold atomic polarized Fermi gases. In three dimensions the ground state of such systems is under strong debate. To gain some insights we investigate a system of one-dimensional strongly interacting polarized Fermi gases. In free space this is an integrable system, and therefore an exact phase diagram can be obtained. We show that an inhomogeneous superfluid state is most widespread in the phase diagram. We consider also the trapped case with an external harmonic trap, where two novel phase separation phases are found using the local density approximation.
We briefly review current research on strongly interacting ultracold atomic polarized Fermi gases. In three dimensions the ground state of such systems is under strong debate. To gain some insights we investigate a system of one-dimensional strongly interacting polarized Fermi gases. In free space this is an integrable system, and therefore an exact phase diagram can be obtained. We show that an inhomogeneous superfluid state is most widespread in the phase diagram. We consider also the trapped case with an external harmonic trap, where two novel phase separation phases are found using the local density approximation.
2007, 36(06): 434-442.
Abstract：
We offer a comprehensive discussion and precise picture of the Kondo effect, Kondo problem, and Kondo resonance. We also discuss their various manifestations in low-dimensional correlated electron systems.
We offer a comprehensive discussion and precise picture of the Kondo effect, Kondo problem, and Kondo resonance. We also discuss their various manifestations in low-dimensional correlated electron systems.
Abstract：
The basic concepts, physical pictures and techniques used in the development of X-ray phase contrast imaging are expounded, including the wave and corpuscular dual properties of light, the concept of phase, and the coherence of conventional and synchrotron radiation X-ray sources. The methods of X-ray phase contrast imaging, the basic principle of 3D imaging, and the latest progress of phase contrast imaging are also discussed. For a better understanding of the progress in this innovative new technique the rather abstract concepts of the first order and second order derivatives of phase are related to the displacement, the tilting and bending distortion of the wave front of the propagating light.
The basic concepts, physical pictures and techniques used in the development of X-ray phase contrast imaging are expounded, including the wave and corpuscular dual properties of light, the concept of phase, and the coherence of conventional and synchrotron radiation X-ray sources. The methods of X-ray phase contrast imaging, the basic principle of 3D imaging, and the latest progress of phase contrast imaging are also discussed. For a better understanding of the progress in this innovative new technique the rather abstract concepts of the first order and second order derivatives of phase are related to the displacement, the tilting and bending distortion of the wave front of the propagating light.
2007, 36(06): 452-459.
Abstract：
X-ray diffraction analysis has become a widely accepted physical analysis and detection technology in pharmaceutic research and development. It is not only applied in the area of chemical drug research, but also plays an exclusive role in Chinese traditional medicine research and quality control.
X-ray diffraction analysis has become a widely accepted physical analysis and detection technology in pharmaceutic research and development. It is not only applied in the area of chemical drug research, but also plays an exclusive role in Chinese traditional medicine research and quality control.
2007, 36(06): 460-464.
Abstract：
The application of powder X-ray diffraction in mineralogy and petrology is reviewed. It is shown that powder X-ray diffraction not only continues to play an important role in the traditional fields of phase identification, quantification and cell parameter determination, studies of isomorphism, polymorphism, polytype and order/disorder phenomena in minerals, petrofabrics and so forth, but have also found applications in the field of crystallization processes, phase transformation and surface study of minerals as well as in defects investigation and structure determination of minerals.
The application of powder X-ray diffraction in mineralogy and petrology is reviewed. It is shown that powder X-ray diffraction not only continues to play an important role in the traditional fields of phase identification, quantification and cell parameter determination, studies of isomorphism, polymorphism, polytype and order/disorder phenomena in minerals, petrofabrics and so forth, but have also found applications in the field of crystallization processes, phase transformation and surface study of minerals as well as in defects investigation and structure determination of minerals.
2007, 36(06): 465-471.
Abstract：
Experimental laboratory studies on the equation of state (EOS) based on laser driven shock waves has become a major way to obtain EOS data for materials above TPa pressures. Recent progress in laser EOS research is presented, with emphasis on the characteristics of laser driven shock waves, measurement methods in laser EOS experiments, research on shock wave planarity, stability and cleanliness, and the experimental results of such research.
Experimental laboratory studies on the equation of state (EOS) based on laser driven shock waves has become a major way to obtain EOS data for materials above TPa pressures. Recent progress in laser EOS research is presented, with emphasis on the characteristics of laser driven shock waves, measurement methods in laser EOS experiments, research on shock wave planarity, stability and cleanliness, and the experimental results of such research.
2007, 36(06): 472-475.
Abstract：
Early warning is one of the most important physical concepts in the reduction of natural disasters for modern society. Prediction/forecast face intrinsic difficulties in physics, so early warning plays a most critical role in practical applications for sustainability. We review the basic concepts and physics of early warning, including the difference between prediction/forecast and early warning, front detection early warning and on-site early warning, and the common physical problems of early warning systems in different fields-finite propagation, the ripple effect, and scaling, as well as the main technical requirements of practical early warning systems.
Early warning is one of the most important physical concepts in the reduction of natural disasters for modern society. Prediction/forecast face intrinsic difficulties in physics, so early warning plays a most critical role in practical applications for sustainability. We review the basic concepts and physics of early warning, including the difference between prediction/forecast and early warning, front detection early warning and on-site early warning, and the common physical problems of early warning systems in different fields-finite propagation, the ripple effect, and scaling, as well as the main technical requirements of practical early warning systems.
2007, 36(06): 476-482.
Abstract：
Due to their non-contact and non-invasion characteristics and a trapping force just in the range of bio-molecular interactions, optical tweezers are finding more and more applications in the measurement of interactions between biological macro-molecules. We describe in detail the development of optical tweezers and their typical applications in the life sciences. It is shown that the activity and mechanisms of bio-molecules can be revealed and understood in new depth with the use of optical tweezers.
Due to their non-contact and non-invasion characteristics and a trapping force just in the range of bio-molecular interactions, optical tweezers are finding more and more applications in the measurement of interactions between biological macro-molecules. We describe in detail the development of optical tweezers and their typical applications in the life sciences. It is shown that the activity and mechanisms of bio-molecules can be revealed and understood in new depth with the use of optical tweezers.
2007, 36(06): 483-488.
Abstract：
Based on recent progress in chirped pulse amplification (CPA) techniques, we describe several new methods to improve the contrast ratio of ultra-intense laser pulses, for example by means of spatial filtering, temporal filtering, improving the contrast ratio of the seed, ring-cavity regenerative amplification, optical parametric CPA, double-CPA, and temporal filtering using nonlinear crystals. Through these new techniques the contrast ratio of ultra-intense laser pulses has been successfully increased to 1011.
Based on recent progress in chirped pulse amplification (CPA) techniques, we describe several new methods to improve the contrast ratio of ultra-intense laser pulses, for example by means of spatial filtering, temporal filtering, improving the contrast ratio of the seed, ring-cavity regenerative amplification, optical parametric CPA, double-CPA, and temporal filtering using nonlinear crystals. Through these new techniques the contrast ratio of ultra-intense laser pulses has been successfully increased to 1011.
