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Purpose To demonstrate a specific skin dose limiting technique in radiotherapy treatment planning for esophageal cancer and carry out a comparative analysis combining with clinical cases. Material and methods Thirty patients with cervical and upper thoracic esophageal carcinoma previously treated in our institution were selected. A treatment plan had been finished previously according to the planning parameters directives from physician and delivered for each patient. In this study, we copied the previously delivered plans in radiotherapy treatment planning system and converted a low dose level (usually 5Gy) to a skin dose limiting structure (SDLS), then we set the objective functions of the SDLS in the Pinnacle Inverse Planning module and re‐optimize the plans to reduce the skin doses. Finally, we compared the dose distribution and other parameters of target volume and organs at risk (OARs) between the old plans and the new plans. Results There was no significant difference in most of OARs sparing. However, for all plans, the maximum dose to the SDLS decreased from 6145.90 ± 416.96 cGy to 5562.09 ± 616.69 cGy with maximum difference of 1361.30 cGy (P

The transition from vegetative to reproductive growth is a key developmental event in a plant's life cycle. The process is mediated by a combination of phytohormones, including melatonin (MT) and strigolactone (SL). Here, the Arabidopsis mutants, d14-1 and max4-1, which are compromised with respect to either SL synthesis or signaling, were shown to flower earlier than wild types. The tissue MT content in both mutants was higher than in wild types, as a result of the up-regulation of various genes encoding enzymes involved in MT synthesis. The abundance in the mutants of transcripts derived from each of the genes SPLs, AP1, and SOC1 was reduced with exogenously supplied MT, while FLC was induced. Plants exposed to a high concentration of MT did not flower earlier than wild types. The tissue MT content of a mutant unable to synthesize caffeic acid O-methyltransferase was less than that of wild type and flowered earlier than did wild types. The suggestion is that the flowering time of Arabidopsis is altered if the tissue content of MT is either higher than ~ 8 ng/g F.W, or lower than ~ 0.9 ng/g. Within this range, SL acts to determine flowering time by its regulation of SPL genes. The application of exogenous SL reduces tissue MT content. The flowering time of the flc-3 mutant was unaffected by exogenously supplying either MT or/and SL. It is proposed that MT acts downstream of SL to activate FLC, inducing a delay to flowering if its concentration lies outside a certain range.

Co-polyimide (co-PI) fibers with outstanding mechanical properties were fabricated via thermal imidization of polyamic acids, derived from a new design of combining the amide and benzimidazole diamine monomers, 4-amino-N-(4-aminophenyl)benzamide (DABA) and 2-(4-aminophenyl)-5-aminobenzimidazole (BIA), with 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA). The crystalline structure and micromorphology of the prepared co-PI fibers were investigated by synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS). The two-dimensional WAXD spectra imply that the co-PI fibers possess a structure between smectic-like and three-dimensionally ordered crystalline phase, and all the obtained fibers are highly oriented along the fiber axis. SAXS patterns exhibit a pair of meridional scattering streaks for the homo-PI (BPDA/BIA) fiber, suggesting the presence of periodic lamellar structure. The incorporation of DABA into the polymer chains destroyed the lamellar structure but led to smaller size of microvoids upon increasing DABA moiety, based on SAXS analysis. The co-PI fibers, with the molar ratio of BIA/DABA being 7/3, exhibited the optimum tensile strength and modulus of 1.96 and 108.3 GPa, respectively, attributed to the well-defined ordered and dense structure. The chemical structure and molecular packing significantly affected the thermal stability of fibers, resulting in the different glass transition temperatures (T-g) from 350 to 380 degrees C. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 183-191

Rigid-rod polyimides (PI) containing benzimidazole moieties were synthesized and spun into fibers by a wet-spinning method. The resultant fibers exhibited an optimum tensile strength of 2.15 GPa and an initial modulus of 105 GPa with a low elongation of 2.2%. The PI fibers consisting of various ratios of 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (TFMB) and 2-(4-aminophenyl)-5-aminobenzimidazole (BIA) were investigated by Fourier transform infrared spectroscopy and two-dimensional wide angle X-ray diffraction (2D WAXD). Direct evidence of hydrogen-bonding involving the NH groups of BIA and the imide carbonyls is presented. Qualitative and quantitative information of this molecular interaction was obtained and discussed. This has been considered as a main factor responsible for the significantly improved mechanical properties of the PI fibers. 2D WAXD and molecular mechanics modeling were used to simulate the structure of the aromatic PI fibers. As a result, the addition of BIA in the main chains is to increase the regularity of the molecule packing, which plays an important role in the enhanced strength of the PI fibers with more BIA loadings.

The paper provides a new stereo-analytical method, which is a combination of the stereographic method and analytical methods, to separate finite removable blocks from the infinite and tapered blocks in discontinuous rock masses. The methodology has applicability to both convex and concave blocks. Application of the methodology is illustrated through examples. Addition of this method to the existing block theory procedures available in the literature improves the capability of block theory in solving practical problems in rock engineering. Copyright © 2003 John Wiley & Sons, Ltd.

A series of co-polyimide fibers were prepared by thermal imidization of copolyamic acids derived from 3,3′,4,4′-biphenyltertracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) in various molar ratios with 2-(4-aminophenyl)−5-aminobenzimidazole (BIA). The dynamic mechanical behaviors of these polyimide (PI) fibers revealed that the glass transition temperature (Tg) was significantly improved upon increasing PMDA content. Heat-drawing process led to dramatic change on the glass transition behavior of BPDA/BIA system, but had a small impact on BPDA/PMDA/BIA co-polyimide fibers. This difference for PI fibers is attributed to the different degree of ordered structure of the fibers affected by heat-drawing. The incorporation of PMDA obviously improved the dimensional stability against high temperature, due to the restricted movement of polymer chains. In addition, the obtained fibers show excellent mechanical and thermal properties because of the strong hydrogen bonding due to the incorporation of benzimidazole moieties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41474.