Integrative analysis of physiology, biochemistry and transcriptome reveals the mechanism of leaf size formation in Chinese cabbage (Brassica rapa L. ssp. pekinensis)

IntroductionThe leaf, the main product organ, is an essential factor in determining the Chinese cabbage growth, yield and quality.MethodsTo explore the regulatory mechanism of leaf size development of Chinese cabbage, we investigated the leaf size difference between two high-generation inbred lines of Chinese cabbage, Y2 (large leaf) and Y7 (small leaf). Furtherly, the transcriptome and cis-acting elements analyses were conducted.Results and DiscussionAccording to our results, Y2 exhibited a higher growth rate than Y7 during the whole growth stage. In addition, the significant higher leaf number was observed in Y2 than in Y7. There was no significant difference in the number of epidermal cells and guard cells per square millimeter between Y2 and Y7 leaves. It indicated that cell numbers caused the difference in leaf size. The measurement of phytohormone content confirmed that GA1 and GA3 mainly play essential roles in the early stage of leaf growth, and IPA and ABA were in the whole leaf growth period in regulating the cell proliferation difference between Y2 and Y7. Transcriptome analysis revealed that cyclins BraA09g010980.3C (CYCB) and BraA10g027420.3C (CYCD) were mainly responsible for the leaf size difference between Y2 and Y7 Chinese cabbage. Further, we revealed that the transcription factors BraA09gMYB47 and BraA06gMYB88 played critical roles in the difference of leaf size between Y2 and Y7 through the regulation of cell proliferation.ConclusionThis observation not only offers essential insights into understanding the regulation mechanism of leaf development, also provides a promising breeding strategy to improve Chinese cabbage yield

Switchable multi-wavelength mode-locked Yb-doped fiber laser using a polarization maintaining 45°-tilted fiber gratings based Lyot filter

We demonstrate a multi-wavelength mode-locked Yb-doped fiber laser by incorporating a pair of polarization maintaining 45° tilted fiber gratings (PM-45°TFG) based Lyot filter. Thanks to the functions of the polarizer and the comb filtering introduced by the Lyot filter, dissipative soliton (DS) pulses centered at 1035.26 nm, 1044.93 nm, 1055.62 nm, 1066.11 nm and 1076.63 nm can be generated respectively by finely tuning the intracavity polarization controllers (PCs). Moreover, the laser also can operate in a multi-wavelength regime via appropriately adjusting the pump power and polarization orientation. The high nonlinearity induced by the long cavity length leads to the generation of h-shaped mode-locked pulse with a repetition rate of 566.27 kHz. In the absence of any disturbance, the laser can operate steadily, that can potentially be used in various fields including wavelength division multiplexing systems etc

Pump-controlled wavelength switchable dissipative soliton mode-locked Yb-doped fiber laser using a 45° tilted fiber grating

We demonstrate a pump-controlled wavelength switchable Yb-doped fiber laser (YDFL) by nonlinear polarization rotation (NPR) for the first time. The polarizer replaced by a 45° tilted fiber grating (45°-TFG) combines with a section of polarization maintaining fiber (PMF) to form a fiber-based birefringent filter. Stable dissipative soliton (DS) with center wavelength of 1068.39 nm is generated under the mode-locked threshold of 277 mW. The operating wavelength switching between 1046.51 nm and 1067.90 nm can be realized via increasing the pump power simply while keeping the polarization controllers (PCs) in a fixed state. The laser maintains stable mode-locking operation at each wavelength, which can be regarded as a type of multi-wavelength ultrafast light source with precise control and integration potential

Optical readout for optical storage with phase jump

A novel, to our knowledge, optical readout for optical storage with phase jump is presented. In the readout scheme two coherent laser beams are focused on an optical disk with one beam scanning along pits and the other along land. When the probe beam scans across a pit, two phase jumps will take place in the interference resultant of the two beams if the phase difference between two beams is prefixed at tau, resulting in a phase pulse of 180 deg. The slopes of rising and falling edges of the phase pulse are infinite, and they are not affected by the intensity variation of the light source, stray light and the vibration of the disk. Therefore this phase pulse can be used to read out the information on an optical disk. The use of phase jump will improve the signal-to-noise ratio of the readout, signal and enhance the density of optical storage. An optical readout with phase jump, was construct;ed, Both the theoretical design and the experimental verification are conducted. Experimental results show that the proposed optical readout is feasible. (C) 1999 Optical Society of America

On the development of nugget growth model for resistance spot welding

In this paper, we developed a general mathematical model to estimate the nugget growth process based on the heat energy delivered into the welds by the resistance spot welding. According to the principles of thermodynamics and heat transfer, and the effect of electrode force during the welding process, the shape of the nugget can be estimated. Then, a mathematical model between heat energy absorbed and nugget diameter can be obtained theoretically. It is shown in this paper that the nugget diameter can be precisely described by piecewise fractal polynomial functions. Experiments were conducted with different welding operation conditions, such as welding currents, workpiece thickness, and widths, to validate the model and the theoretical analysis. All the experiments confirmed that the proposed model can predict the nugget diameters with high accuracy based on the input heat energy to the welds. (C) 2014 AIP Publishing LLC

Study of safety operation of AC resistance spot welding system

This study deals with the safety operation of AC resistance spot welding (RSW) system. The input of the RSW system is the firing angle of the silicon-controlled rectifier (SCR) during each control cycle. Wrongly choosing a firing angle may induce disastrous consequence. The range of firing angle depends on the system's power factor angle; the relation between the firing angle, power factor angle and conduction angle is highly non-linear. After comparing three methods, a simple mathematical model is proposed in this study to facilitate the online calculation of the power factor angle and selection of the proper firing angle, so that the safety operation of RSW system can be guaranteed. In this condition, the RSW machine can work at the machine's the most capacity, the calculated value of power factor angle should be the lowest limit for actual selected firing angle of SCR. Finally, experimental results confirmed the effectiveness of the proposed mathematical model. © The Institution of Engineering and Technology 2013

Online Measuring Power Factor in AC Resistance Spot Welding

The power factor is a very important process variable in ac resistance spot welding (RSW) operation. Because of the variation of welding load during the welding process, the power factor is a time-varying variable. The power factor of RSW cannot be obtained online because the value of power factor angle cannot be directly measured in real time. After analyzing the electrical structure of RSW, a new algorithm for measuring the power factor angle in real time is developed. Then, an integrated algorithm for calculating the power factor on a practical discrete system in real time is proposed. Experiments were conducted to validate the effectiveness of the proposed method. The experimental results showed that the proposed algorithm can be used to obtain more accurate values of the power factor angle than using other methods over a very large operation range. The final results of power factors obtained from the proposed algorithm are very close to the results from the numerical simulation

Interferometer for small-angle measurement based on total internal reflection

We describe a new method for angle measurement based on the internal-reflection effect and heterodyne interferometry. A novel prism assembly is designed that can always parallel retroreflect the incoming light beams so the optical configuration is compact. As a differential common-path optical configuration is integrated into the design, the linearity of the method is greatly improved. Details of theoretical analysis of the method and experimental verification of the principle are presented. The resolution can be better than 0.3 are sec. The experimental results and further improvements of the proposed method are also addressed. (C) 1998 Optical Society of America