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Analysis on the DNA Fingerprinting of Aspergillus Oryzae Mutant Induced by High Hydrostatic Pressure
WANG Hua, ZHANG Jian, YANG Fan, WANG Kai, SHEN Si-Le**, LIU Bing-Bing, ZOU Bo**, ZOU Guang-Tian
Chin. Phys. Lett. 2011, 28 (1):
010703
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DOI: 10.1088/0256-307X/28/1/010703
The mutant strains of aspergillus oryzae (HP300a) are screened under 300 MPa for 20 min. Compared with the control strains, the screened mutant strains have unique properties such as genetic stability, rapid growth, lots of spores, and high protease activity. Random amplified polymorphic DNA (RAPD) and inter simple sequence repeats (ISSR) are used to analyze the DNA fingerprinting of HP300a and the control strains. There are 67.9% and 51.3% polymorphic bands obtained by these two markers, respectively, indicating significant genetic variations between HP300a and the control strains. In addition, comparison of HP300a and the control strains, the genetic distances of random sequence and simple sequence repeat of DNA are 0.51 and 0.34, respectively.
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Factorial Correlators and Oscillatory Multiplicity Moments at the CERN SPS Energy for Ring-Like and Jet-Like Events
Prabir Kumar Haldar**, Sanjib Kumar Manna
Chin. Phys. Lett. 2011, 28 (1):
012502
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DOI: 10.1088/0256-307X/28/1/012502
We present an analysis of ring-like and jet-like events in terms of factorial correlations and oscillatory multiplicity moments of 32S–Ag/Br interactions at 200 A GeV. The investigation reveals that the correlated moments increase with decrease in bin−bin separation D, following the power law, which suggests the presence of an intermittent nature of self−similar dynamical fluctuations pattern for ring-like and jet-like events. The analysis further shows that the strength of the non-statistical fluctuations is larger for jet-like events than those of ring-like events and total events. However, ring-like and jet-like events are not to be consistent with the total events of the α model of intermittency. To go beyond the lower order correlation, the oscillatory multiplicity moments are used to study the higher order correlation. The ratios Hq (cumulant over factorial moments, Kq/Fq) are determined for ring-like, jet-like and the total events. The presence of few-particle short range correlation is established. It is extremely interesting to observe that the oscillations of ring-like events are different from the jet-like events and the total events. However, in almost all the cases, the simulated interactions fail to replicate the experimental results.
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Computerized Control and Operation of Rutherford Backscattering/Channeling for an in situ Ion Beam System and Its Application for Measurement of Si(001) and ZnO(001)
HE Jun, J. C. LEE, LI Ming, WANG Ze-Song, LIU Chuan-Sheng, FU De-Jun**
Chin. Phys. Lett. 2011, 28 (1):
012901
.
DOI: 10.1088/0256-307X/28/1/012901
A computer-automated Rutherford backscattering/channeling (RBS/C) system is developed to provide in situ ion beam analysis of the accelerator-TEM system in Wuhan University. The basic system components are a PC equipped with a multichannel analyzer data acquisition board, motion control hardware including the Panmure stepping motor controller and integrated circuit modules, and a Labview programmed operating system with associated electronics. Single crystalline Si(001) and ZnO(001) implanted with Mn ions were characterized with this computerized setup. The crystalline quality χmin and channeling half angle of Si(001) were measured to be 4.65% and 0.52°, respectively, which are comparable to theoretical values 4.2% and 0.32°. The ion implantation induced damage depth profile derived from channeling and random spectrum is in reasonable agreement with the result calculated by the SRIM Monte-Carlo simulation code.
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Frequency Measurement of the Electric Quadrupole Transition in a Single Laser-Cooled 40Ca+
LIU Qu, , HUANG Yao, , CAO Jian, , OU Bao-Quan, , GUO Bin, **, GUAN Hua, HUANG Xue-Ren, ***, GAO Ke-Lin, ***
Chin. Phys. Lett. 2011, 28 (1):
013201
.
DOI: 10.1088/0256-307X/28/1/013201
The optical frequency of the
4s2S1/2–3d2D5/2 transition in a single trapped and laser−cooled 40Ca+ ion is measured with an optical frequency comb system referenced to a hydrogen maser. A 729−nm laser can be locked to the clock transition about ten hours and the Allan deviation is better than 2×10-14/1000s.
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Measurement of Local Gravity via a Cold Atom Interferometer
ZHOU Lin, , XIONG Zong-Yuan, , YANG Wei, , TANG Biao, , PENG Wen-Cui, , WANG Yi-Bo, , XU Peng, , WANG Jin, ZHAN Ming-Sheng, **
Chin. Phys. Lett. 2011, 28 (1):
013701
.
DOI: 10.1088/0256-307X/28/1/013701
We demonstrate a precision measurement of local gravity acceleration g in Wuhan by a compact cold atom interferometer. The atom interferometer is in vertical Mach–Zehnder configuration realized using a π/2−π-π/2 Raman pulse sequence. Cold atoms were prepared in a magneto-optical trap, launched upward to form an atom fountain, and then coherently manipulated to interfere by stimulated Raman transition. Population signal vs Raman laser phase was recorded as interference fringes, and the local gravity was deduced from the interference signal. We have obtained a resolution of 7×10−9 g after an integration time of 236 s under the best vibrational environment conditions. The absolute g value was derived from the chirp rate with a difference of 1.5×10−7 g compared to the gravity reference value. The tidal phenomenon was observed by continuously monitoring the local gravity over 123 h.
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Time-Delay Signature of Chaotic Vertical-Cavity Surface-Emitting Lasers with Polarization-Rotated Optical Feedback
XIANG Shui-Ying**, PAN Wei, YAN Lian-Shan, LUO Bin, ZOU Xi-Hua, JIANG Ning, WEN Kun-Hua
Chin. Phys. Lett. 2011, 28 (1):
014203
.
DOI: 10.1088/0256-307X/28/1/014203
To quantitatively evaluate the time-delay (TD) signatures of chaotic signals generated by vertical-cavity surface-emitting lasers (VCSELs) with polarization-rotated optical feedback (PROF), we propose four cases of resolution coefficients R based on correlation functions. The resolution coefficient characteristics for the x–polarization (XP) mode, y–polarization (YP) mode and the total output are considered. The dependences of R on the feedback strength and feedback delay are discussed and compared carefully. The two–dimensional maps of R show that the TD signatures for the single polarization mode (i.e., XP or YP mode) are much more difficult to retrieve than those for the total output in the entire parameter space. Thus, by using single polarization mode as a chaotic carrier, the TD signatures are extremely difficult to be identified, which contributes a lot in the security-enhanced VCSELs-based chaotic optical communication systems.
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Design of Waveguide Integrated Ge-Quantum-Well Electro-Absorption Modulators
ZHAO Hong-Wei**, HU Wei-Xuan, XUE Chun-Lai, CHENG Bu-Wen, WANG Qi-Ming
Chin. Phys. Lett. 2011, 28 (1):
014204
.
DOI: 10.1088/0256-307X/28/1/014204
We present two designs for a waveguide Ge-quantum-well electro-absorption modulator. In our designs, the strip SOI waveguides are butt-coupled and evanescent-coupled to the modulator, respectively. The proposed Ge-quantum-well electro-absorption modulator is based on quantum-confined Stark effect (QCSE), having a 3-dB bandwidth above 50 GHz, as well as a low switching power (around 60 fJ/bit at 1435 nm). In the butt-coupled design, the optimized extinction ratio is up to 11.4 dB, while the insertion loss is only 6.74 dB. For the second one, which utilizes evanescent coupling, the extinction ratio and insertion loss are 9.18 dB and 6.72 dB, respectively.
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Simulation of Light Intensification Induced by Defects of Polished Fused Silica
WANG Feng-Rui, LIU Hong-Jie, HUANG Jin, ZHOU Xin-Da, JIANG Xiao-Dong**, WU Wei-Dong, ZHENG Wan-Guo, JU Xin
Chin. Phys. Lett. 2011, 28 (1):
014206
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DOI: 10.1088/0256-307X/28/1/014206
Light intensity distribution in the vicinity of inclusions and etched cracks in polished fused silica at wavelength scale are simulated by using the finite-difference time-domain algorithm. Light intensity enhancement factor as functions of diameter and refractive index of inclusions are investigated, more than 10 times that of incident beam is obtained in the simulation. We model the etched crack in close proximity to a real structure, which is characterized by AFM. We find that the peak light intensity of the crack is a function of its cross sectional breadth depth ratio, providing good hints for the effective processing of fused silica samples to improve the damage threshold.
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Correlation of Photosensitization and Binding Mode of Methylene Blue and DNA
LIU Tao, ZHANG Feng, CHEN Ping, TANG Guo-Qing, LIN Lie**
Chin. Phys. Lett. 2011, 28 (1):
014208
.
DOI: 10.1088/0256-307X/28/1/014208
Binding of methylene blue (MB) and DNA, photosensitization of MB in DNA, and correlation of photosensitization and binding mode are studied at different concentration ratios of DNA and MB. The absorption spectra indicate that the electrostatic binding is the main mode at low γ ratios (γ≤2), while at high γ ratios (γ>2) the intercalative binding is dominated. Studies on dynamics of photosensitization formation of singlet oxygen (1O2) for MB in DNA are carried out by using time−resolved technology. There are no obvious changes of the singlet oxygen lifetime and the triplet state MB molecule (MB3+∗) lifetime at low ratios, they are about 4 μs and 1 µs, respectively. However, we could not obtain the 1O2 lifetime and MB3+∗ lifetime due to the great decrease of 1O2 phosphorescence signals at high ratios. These results show that the photosensitization and binding mode of MB in DNA possess high correlation. When MB binds with DNA by electrostatic interaction, type−II photosensitization of MB plays a major role in photodynamic effect, the damage of DNA probably could be ascribed to 1O2. However, at high ratios, binding mode between MB and DNA turns to intercalative binding, which greatly weakens the type−II photosensitization process. Charge transfer between MB and DNA possibly becomes the main damage mechanism.
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Preparation and Photoluminescence Properties of Eu2+−Doped Oxyapatite-Type SrxLa10−x (SiO4)6O3−x/2
CUI Zhao-Feng, YUAN Shuang-Long, **, YANG Yun-Xia, Franç, ois CHEVIRE **, Franck TESSIER, CHEN Guo-Rong
Chin. Phys. Lett. 2011, 28 (1):
014209
.
DOI: 10.1088/0256-307X/28/1/014209
Eu2+−doped oxyapatite SrxLa10−x(SiO4)6O3−x/2 phosphors are prepared by solid-state reaction at high temperatures under reducing atmosphere. Their crystal structures and photoluminescence are investigated by x-ray diffraction (XRD) and fluorescence spectroscopy, respectively. The XRD results indicate that the samples are pure oxyapatite phase (P63/m space group). The fluorescence spectra show two peaks corresponding to two sites (4f and 6h sites) for Eu2+ in the host lattice. As the Eu2+ content influences the intensity ratio of the two observed emission peaks, the photoluminescence mechanism is discussed.
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Analysis of Modified Williamson-Hall Plots on GaN Layers
LIU Jian-Qi, , QIU Yong-Xin, WANG Jian-Feng, XU Ke**, YANG Hui
Chin. Phys. Lett. 2011, 28 (1):
016101
.
DOI: 10.1088/0256-307X/28/1/016101
Williamson–Hall (W-H) analysis is often used to separate the lateral coherence length (LCL) broadening and dislocation broadening on the ω−scan with a Lorentzian distribution. However, besides the LCL broadening and dislocation broadening, curvature also can broaden the ω−scan peak. Usually, the ω−scan can be described by a Pseudo-Voigt (P-V) function more precisely than a Lorentzian function. Based on the P-V fit peak profile, we modify the W-H plots. Both LCL broadening and curvature broadening can be eliminated from (00l) ω-scans plots simultaneously, and a reliable tilt can be obtained. This method is a good complementary for the existing method, but is more convenient. Although we focuse on GaN layers, the results are applicable to a wide range of other materials having mosaic structures.
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Ion-implanted Mechanism of the Deposition Process for Diamond-Like Carbon Films
WANG Xue-Min, WU Wei-Dong**, WANG Yu-Ying, WANG Hai-Ping, GE Fang-Fang, TANG Yong-Jian, JU Xin
Chin. Phys. Lett. 2011, 28 (1):
016102
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DOI: 10.1088/0256-307X/28/1/016102
Due to the local densification, high-energy C and doped ions can greatly affect the bonding configurations of diamond-like carbon films. We investigate the corresponding affection of different incident ions with energy from 10 eV to 600 eV by Monte Carlo methods. The ion-implanted mechanism called the subplantation (for C, N, O, W, Y, etc.) is confirmed. Obvious thermal effect could be induced by the subplantation of the incident ions. Further, the subplantation of C ions is proved by in situ reflection high energy electron diffraction (RHEED). The observation from an atomic force microscope (AFM) indicates that the initial implantation of C ions might result in the final primitive-cell-like morphology of the smooth film (in an area of 1.2mm×0.9mm, rms roughness smaller than 20 nm by Wyko).
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Negative Bias Temperature Instability
CAO Yan-Rong**, MA Xiao-Hua, HAO Yue, ZHU Min-Bo, TIAN Wen-Chao, ZHANG Yue
Chin. Phys. Lett. 2011, 28 (1):
017301
.
DOI: 10.1088/0256-307X/28/1/017301
Different phenomena are observed under negative gate voltage stress which is smaller than the previous degradation stress in PMOSFETs with different oxide thicknesses. We adopt the real time method to make a point of the drain current to study the degradation and recovery of negative bias temperature instability (NBTI). For the device with thin oxide, recovery phenomenon appears when smaller negative voltage stress was applied, due to the more influencing oxide charges detrapping effects than the interface states. For the device with thick oxide, not recovery but degradation phenomenon comes forth. As many charges are trapped in the deeper position and higher energy level in the oxide, these charges can not be detrapped. Therefore, the effect of the charge detrapping is smaller than that of the interface states in the thick oxide. The degradation presents itself during the 'recovery' time.
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Chemical Quenching of Positronium in CuO/Al2O3 Catalysts
ZHANG Hong-Jun, LIU Zhe-Wen, CHEN Zhi-Quan**, WANG Shao-Jie**
Chin. Phys. Lett. 2011, 28 (1):
017802
.
DOI: 10.1088/0256-307X/28/1/017802
CuO/Al2O3 catalysts were prepared by mixing CuO and γ−Al2O3 nanopowders. Microstructure and chemical environment of the catalysts are characterized by positron annihilation spectroscopy. The positron annihilation lifetime measurements reveal two long lifetime components τ3 and τ4, which correspond to ortho−positronium (o-Ps) annihilating in microvoids and large pores, respectively. With increasing CuO content from 0 to 40 wt%, both τ4 and its intensity I4 show significant decrease, which indicates quenching effect of o−Ps. The para-positronium (p-Ps) intensities derived from multi-Gaussian fitting of the coincidence Doppler broadening spectra also decrease gradually with increasing CuO content. This excludes the possibility of spin-conversion of positronium. Therefore, the chemical quenching by CuO is probably responsible for the decrease of o-Ps lifetime. Variation in the o-Ps annihilation rate λ4 (1/τ4) as a function of CuO content can be well fitted by a straight line, and the slope of the fitting line is (1.83±0.05)×107 s−1.
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Trimeric Hydrogen Bond in Geometrically Frustrated Hydroxyl Cobalt Halogenides
LIU Xiao-Dong, **, Hagihala Masato, ZHENG Xu-Guang, **, TAO Wan-Jun, MENG Dong-Dong, ZHANG Sen-Lin, GUO Qi-Xin
Chin. Phys. Lett. 2011, 28 (1):
017803
.
DOI: 10.1088/0256-307X/28/1/017803
The mid-infrared absorption spectra of geometrically frustrated hydroxyl cobalt halogenides Co2(OH)3Cl and Co2(OH)3Br are measured by FTIR spectrometers, and the stretching vibrational modes of hydroxyl groups are found to be 3549 cm−1 and 3524 cm−1 respectively. Through finding their true terminal O–H group stretching vibration frequencies, we obtain 107 cm−1 and 99 cm−1 red shift caused by the corresponding O–H⋅⋅⋅Cl and O–H⋅⋅⋅Br hydrogen bonds. Rarely reported trimeric hydrogen bonds (Co3≡O–H)3⋅⋅⋅Cl/Br are pointed out to demonstrate the relative weakness of this kind of hydrogen bond which may have a critical effect on the lattice symmetry and magnetic structures.
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Computational Investigation of InxGa1−xN/InN Quantum-Dot Intermediate-Band Solar Cell
DENG Qing-Wen**, WANG Xiao-Liang, , YANG Cui-Bai, XIAO Hong-Ling, WANG Cui-Mei, YIN Hai-Bo, HOU Qi-Feng, BI Yang, LI Jin-Min, WANG Zhan-Guo, HOU Xun
Chin. Phys. Lett. 2011, 28 (1):
018401
.
DOI: 10.1088/0256-307X/28/1/018401
An InxGa1−xN/InN quantum-dot intermediate-band solar cell is calculated by means of solving the Schrödinger equation according to the Kronig–Penney model. Based on particular assumptions, the power conversion efficiency is worked out. The results reveal that the InxGa1−xN/InN quantum-dot intermediate-band solar cell manifests much larger power conversion efficiency than that of p-n junction solar cells, and the power conversion efficiency strongly depends on the size of the quantum dot and the interdot distance.
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Hidden Tree Structure is a Key to the Emergence of Scaling in the World Wide Web
ZHENG Bo-Jin, **, WANG Jian-Min, CHEN Gui-Sheng, JIANG Jian, SHEN Xian-Jun
Chin. Phys. Lett. 2011, 28 (1):
018901
.
DOI: 10.1088/0256-307X/28/1/018901
Preferential attachment is the most popular explanation for the emergence of scaling behavior in the World Wide Web, but this explanation has been challenged by the global information hypothesis, the existence of linear preference and the emergence of new big internet companies in the real world. We notice that most websites have an obvious feature that their pages are organized as a tree (namely hidden tree) and hence propose a new model that introduces a hidden tree structure into the Erdös–Rényi model by adding a new rule: when one node connects to another, it should also connect to all nodes in the path between these two nodes in the hidden tree. The experimental results show that the degree distribution of the generated graphs would obey power law distributions and have variable high clustering coefficients and variable small average lengths of shortest paths. The proposed model provides an alternative explanation to the emergence of scaling in the World Wide Web without the above-mentioned difficulties, and also explains the "preferential attachment" phenomenon.
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A Simple Model of Interaction between Journals, Authors and Editorial Board Members
ZOU Sheng-Rong, XU Ying-Ying, XU Xiu-Lian, WANG Jian, HE Da-Ren**
Chin. Phys. Lett. 2011, 28 (1):
018902
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DOI: 10.1088/0256-307X/28/1/018902
Recently, quantitative study on complex systems has become an attractive research area for physicists. Human scientific activity, including scientific paper publication, is an important complex system and therefore deserves an investigation. We present a simple model to describe the interaction between journals, authors and editorial board members. In the model the probabilities, with which a journal accepts papers from an author or invites him as an editorial board member, obey normal distributions. However, the most probable value of the latter distribution shifts such that the journal can have higher level authors being its editorial board members. The analytic derivation by the model is in rather good agreement with the empirical observation from the selected fifteen worldwide journals with different impact factors.
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Radioactivity Levels and Gamma-Ray Dose Rate in Soil Samples from Kohistan (Pakistan) Using Gamma-Ray Spectrometry
Hasan M. Khan*, M. Ismail, K. Khan, P. Akhter
Chin. Phys. Lett. 2011, 28 (1):
019301
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DOI: 10.1088/0256-307X/28/1/019301
The analysis of naturally occurring radionuclides (226Ra, 232Th and 40K) and an anthropogenic radionuclide 137Cs is carried out in some soil samples collected from Kohistan district of N.W.F.P. (Pakistan), using gamma−ray spectrometry. The gamma spectrometry is operated using a high purity Germanium (HPGe) detector coupled with a computer based high resolution multi channel analyzer. The specific activity in soil ranges from 24.72 to 78.48 Bq⋅kg−1 for 226Ra, 21.73 to 75.28 Bq⋅kg−1 for 232Th, 7.06 to 14.9 Bq⋅kg−1 for 137Cs and 298.46 to 570.77 Bq⋅kg−1 for 40K with the mean values of 42.11, 43.27, 9.5 and 418.27 Bq⋅kg−1, respectively. The radium equivalent activity in all the soil samples is lower than the safe limit set in the OECD report (370 Bq⋅kg−1). Man-made radionuclide 137Cs is also present in detectable amount in all soil samples. Presence of 137Cs indicates that the samples in this remote area also receive some fallout from nuclear accident in Chernobyl power plant in 1986. The internal and external hazard indices have the mean values of 0.48 and 0.37 respectively. Absorbed dose rates and effective dose equivalents are also determined for the samples. The concentration of radionuclides found in the soil samples during the present study is nominal and does not pose any potential health hazard to the general public.
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63 articles
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