Mesophase structure discovered through in-situ X-ray measurement in drawing process of poly(ethylene 2,6-naphthalene dicarboxylate) fiber

The structure development in the continuous laser-heated drawing process of poly(ethylene 2,6-naphthalene dicarboxylate) (PEN) fiber was analyzed by in-situ X-ray diffraction measurement. Because of the rapid and uniform laser heating, and the resultant steady-state nature of the necking-drawing, the structure development after the on-set of necking could be measured in the time resolution of several hundred microseconds. We found for the first time the temporal appearance of meridional (001') diffraction at several milliseconds after the on-set of necking indicating that the mesophase structure similar to the one reported for poly(ethylene terephthalate) was also formed in the initial stage of fiber structure development of PEN. The d-spacing of the (001') diffraction 1.230 +/- 0.003 nm was shorter than the c-axis lengths of both alpha and beta crystals.ArticlePOLYMER. 50(19):4429-4431 (2009)journal articl

Development of a Lidocaine-Loaded Alginate/CMC/PEO Electrospun Nanofiber Film and Application as an Anti-Adhesion Barrier

Surgery, particularly open surgery, is known to cause tissue/organ adhesion during healing. These adhesions occur through contact between the surgical treatment site and other organ, bone, or abdominal sites. Fibrous bands can form in unnecessary contact areas and cause various complications. Consequently, film- and gel-type anti-adhesion agents have been developed. The development of sustained drug delivery systems is very important for disease treatment and prevention. In this study, the drug release behavior was controlled by crosslinking lidocaine-loaded alginate/carboxymethyl cellulose (CMC)/polyethylene oxide (PEO) nanofiber films prepared by electrospinning. Lidocaine is mainly used as an anesthetic and is known to have anti-adhesion effects. Our results show that drug release is regulated by the crosslinking degree of the lidocaine-loaded alginate/CMC/PEO film. The drug release behavior was confirmed by HPLC, and, as a result, an excellent anti-adhesion barrier was developed that can be applied to treat patients in the medical field

Generalization in a Two-Layer Neural Network With Multiple Outputs

We study generalization in a fully connected two-layer neural network with multiple output nodes. Similarly to the learning of fully connected committee machine, the learning is characterized by a discontinuous phase transition between the permutation symmetric phase and the permutation symmetry breaking phase. We find that the learning curve in the permutation symmetric phase is universal, irrespective of the number of output nodes. The first order phase transition point, i.e. the critical number of examples required for perfect learning, is inversely proportional to the number of outputs. The replica calculation shows good agreement with Monte Carlo simulation. Typeset using REVT E X 1 Learning from examples in layered neural networks has been a common interest of statistical mechanics and other related areas such as computer science and mathematical statistics for the last few years [1]. Following the statistical mechanics formulation of Gardner [2,3], there have been many efforts..

Medical X-band linear accelerator for high-precision radiotherapy

Purpose: Recently, high-precision radiotherapy systems have been developed by integrating computerized tomography or magnetic resonance imaging to enhance the precision of radiotherapy. For integration with additional imaging systems in a limited space, miniaturization and weight reduction of the linear accelerator (linac) system have become important. The aim of this work is to develop a compact medical linac based on 9.3 GHz X-band RF technology instead of the S-band RF technology typically used in the radiotherapy field. Methods: The accelerating tube was designed by 3D finite-difference time-domain and particle-in-cell simulations because the frequency variation resulting from the structural parameters and processing errors is relatively sensitive to the operating performance of the X-band linac. Through the 3D simulation of the electric field distribution and beam dynamics process, we designed an accelerating tube to efficiently accelerate the electron beam and used a magnetron as the RF source to miniaturize the entire linac. In addition, a side-coupled structure was adopted to design a compact linac to reduce the RF power loss. To verify the performance of the linac, we developed a beam diagnostic system to analyze the electron beam characteristics and a quality assurance (QA) experimental environment including 3D lateral water phantoms to analyze the primary performance parameters (energy, dose rate, flatness, symmetry, and penumbra) The QA process was based on the standard protocols AAPM TG-51, 106, 142 and IAEA TRS-398. Results: The X-band linac has high shunt impedance and electric field strength. Therefore, even though the length of the accelerating tube is 37 cm, the linac could accelerate an electron beam to more than 6 MeV and produce a beam current of more than 90 mA. The transmission ratio is measured to be approximately 30% similar to 40% when the electron gun operates in the constant emission region. The percent depth dose ratio at the measured depths of 10 and 20 cm was approximately 0.572, so we verified that the photon beam energy was matched to approximately 6 MV. The maximum dose rate was measured as 820 cGy/min when the source-to-skin distance was 80 cm. The symmetry was smaller than the QA standard and the flatness had a higher than standard value due to the flattening filter-free beam characteristics. In the case of the penumbra, it was not sufficiently steep compared to commercial equipment, but it could be compensated by improving additional devices such as multileaf collimator and jaw. Conclusions: A 9.3 GHz X-band medical linac was developed for high-precision radiotherapy. Since a more precise design and machining process are required for X-band RF technology, this linac was developed by performing a 3D simulation and ultraprecision machining. The X-band linac has a short length and a compact volume, but it can generate a validated therapeutic beam. Therefore, it has more flexibility to be coupled with imaging systems such as CT or MRI and can reduce the bore size of the gantry. In addition, the weight reduction can improve the mechanical stiffness of the unit and reduce the mechanical load.11Nsciescopu