A Scenario on the Stepwise Evolution of the Genetic Code

It is believed that in the RNA world the operational (ribozymes) and the informational (riboscripts) RNA molecules were created with only three (adenosine, uridine, and guanosine) and two (adenosine and uridine) nucleosides, respectively, so that the genetic code started uncomplicated. Ribozymes subsequently evolved to be able to cut and paste themselves and riboscripts were acceptive to rigorous editing (adenosine to inosine); the intensive diversification of RNA molecules shaped novel cellular machineries that are capable of polymerizing amino acids—a new type of cellular building materials for life. Initially, the genetic code, encoding seven amino acids, was created only to distinguish purine and pyrimidine; it was later expanded in a stepwise way to encode 12, 15, and 20 amino acids through the relief of guanine from its roles as operational signals and through the recruitment of cytosine. Therefore, the maturation of the genetic code also coincided with (1) the departure of aminoacyl-tRNA synthetases (AARSs) from the primordial translation machinery, (2) the replacement of informational RNA by DNA, and (3) the co-evolution of AARSs and their cognate tRNAs. This model predicts gradual replacements of RNA-made molecular mechanisms, cellular processes by proteins, and informational exploitation by DNA

Switchable polarization manipulation, optical logical gates and conveyor belt based on U-shaped \ce{VO2} nanoholes

Based on U-shaped plasmonic nanoholes in an \ce{Au-VO2-Au} film, we propose to achieve several switchable functions at the telecom wavelength by transition from the \ce{VO2} semiconductive state to the metallic state. The first is the polarization manipulation of four different polarization states ($x\&y$-polarization, LCP, and RCP). An array of U-shaped holes constitutes of the high efficiency SPP splitter, and thus the spin-encoded optical logical gates can be achieved. Furthurmore, we prove that a nano-optical conveyor belt can be build up with such U-shaped holes, making the transport of nanoparticles over the film efficiency by transforming between two spin states periodically, and the transport direction switchably along with the \ce{VO2} phase

Application of Wavelet Analysis in Detecting Runway Foreign Object Debris

Foreign Object Debris (FOD) is dangerous for aircraft safety. And it can be suggested to use image processing technology on the FOD’s detection. Depending on image processing system, a major sub-system in FOD detecting system on the runway, FOD image will be observed efficiently and rapidly with few economy costs and highly accuracy and reliability. The paper analyses the characteristics and principles of wavelet transformation algorithm and applies wavelet theory on FOD’s identification and detection. Identifying the FOD’s shape and marking characteristic point on the runway under poor visual background would be accomplished by programming in MATLAB using wavelet algorithm. The results show that the plan is applicable. Besides that, it brings about profound significance for realizing the real-time detecting on the FOD and testing with more feasibility and efficiency.

Preparation and Characterization of Sustained Release Matrix Tablets of Tizanidine Hydrochloride for Spinal Injuries

Purpose: To formulate matrix type sustained-release (SR) tablets of tizanidine hydrochloride (TH) for prolonged drug release and improvement in motor activity after spinal injuries.Methods: Matrix tablets were prepared by the wet granulation method using four polymers (hydroxyl propyl methyl cellulose [HPMC] K 100, ethyl cellulose [EC], guar gum, and polyvinylpyrrolidone (PVP K30) and characterized for hardness, friability, drug content, swelling, weight variation, in vitro drug release, and in vivo motor function activity using the spinal injury rat model.Results: All tablets showed good drug content, hardness, and other physicochemical properties. The tablet formulations showed a percent drug release ranging from 92.54 ± 1.02 to 98.56 ± 1.26 % at the end of 12 h. Using the spinal injury rat model, negative control had a motor activity of only 12.75 %, while F4 (containing HPMC, EC, and PVP) and F5 (containing EC, guar gum, and PVP) had motor activities of 62.25% and 57.5%, respectively, compared with 68.0 % for normal controls.Conclusion: SR matrix tablets of TH showed significant improvement in motor activity in post-traumatic spinal injury rat model.Keywords: Sustained release tablet, Spinal injuries, Matrix tablet, Tizanidine hydrochlorid