E-beam-enhanced solid-state mechanical amorphization of alpha-quartz: Reducing deformation barrier via localized excess electrons as mobile anions

Under hydrostatic pressure, alpha-quartz undergoes solid-state mechanical amorphization wherein the interpenetration of SiO4 tetrahedra occurs and the material loses crystallinity. This phase transformation requires a high hydrostatic pressure of 14 GPa because the repulsive forces resulting from the ionic nature of the Si-O bonds prevent the severe distortion of the atomic configuration. Herein, we experimentally and computationally demonstrate that e-beam irradiation changes the nature of the interatomic bonds in alpha-quartz and enhances the solid-state mechanical amorphization at nanoscale. Specifically, during in situ uniaxial compression, a larger permanent deformation occurs in alpha-quartz micropillars compressed during e-beam irradiation than in those without e-beam irradiation. Microstructural analysis reveals that the large permanent deformation under e-beam irradiation originates from the enhanced mechanical amorphization of alpha-quartz and the subsequent viscoplastic deformation of the amorphized region. Further, atomic-scale simulations suggest that the delocalized excess electrons introduced by e-beam irradiation move to highly distorted atomic configurations and alleviate the repulsive force, thus reducing the barrier to the solid-state mechanical amorphization. These findings deepen our understanding of electron-matter interactions and can be extended to new glass forming and processing technologies at nano- and microscale.Comment: 24 pages, 6 figure

Xanthogranulomatous Cystitis Arising from the Posterior Wall of the Bladder

Xanthogranulomatous cystitis is a rare, benign chronic inflammatory disease of unknown etiology. Herein we report a case of a 41-year-old man who presented with painless hematuria and a bladder mass on imaging studies

Helical tomotherapy with concurrent capecitabine for the treatment of inoperable pancreatic cancer

<p>Abstract</p> <p>Background</p> <p>Helical tomotherapy, an advanced intensity-modulated radiation therapy with integrated CT imaging, permits highly conformal irradiation with sparing of normal tissue. Capecitabine, a pro-drug of 5-FU that induces thymidine phosphorylase can achieve higher levels of intracellular 5-FU when administered concurrently with radiation. We evaluated the feasibility as well as the clinical outcome of concurrent administration of capecitabine with tomotherapy in patients with advanced pancreatic cancer.</p> <p>Methods</p> <p>Nineteen patients with advanced pancreatic cancer including primarily unresectable disease and recurrence after curative surgery were included in the study. Two planning target volumes (PTV) were entered: PTV1 is gross tumor volume; and PTV2, the volume of the draining lymph nodes. The total doses to target 1 and target 2 were 55 and 50 Gy, respectively. Capecitabine at 1600 mg/m²/day was administered on each day of irradiation.</p> <p>Results</p> <p>Twenty six measurable lesions were evaluated. Overall in-field response rate was 42.3%; partial responses were achieved in 53.3% of the pancreatic masses, 28.6% of distant metastatic lesions and 25.0% of regional lymph nodes. The median duration of follow-up after tomotherapy was 6.5 months. None of the lesions showed in-field progression. Treatment was well tolerated with only minor toxicities such as grade 1 nausea (one patient), grade 1 hand-foot syndrome (one patient) and grade 1/2 fatigue (three patients).</p> <p>Conclusions</p> <p>Helical tomotherapy with concurrent capecitabine is a feasible option without significant toxicities in patients with advanced pancreatic cancer. We achieved excellent conformal distribution of radiation doses and minimal treatment-related toxicities with promising target volume responses.</p

Lack of Mitochondrial DNA Sequence Divergence between Two Subspecies of the Siberian Weasel from Korea: Mustela sibirica coreanus from the Korean Peninsula and M. s. quelpartis from Jeju Island

The objective of this study was to determine the degree of mitochondrial DNA (mtDNA) divergence between two subspecies of Mustela sibirica from Korea (M. s. coreanus on the Korean Peninsula and M. s. quelpartis on Jeju Island) and to examine the taxonomic status of M. s. quelpartis. Thus, we obtained complete sequences of mtDNA cytochrome b gene (1,140 bp) from the two subspecies, and these sequences were compared to a corresponding haplotype of M. s. coreanus, downloaded from GenBank. From this analysis, it was observed that the sequences from monogenic M. s. quelpartis on Jeju Island were identical to the sequences of four M. s. coreanus from four locations across the Korean Peninsula, and that the two subspecies formed a single clade; the average nucleotide distance between the two subspecies was 0.26% (range, 0.00 to 0.53%). We found that the subspecies quelpartis is not genetically distinct from the subspecies coreanus, and that this cytochrome b sequencing result does not support the current classification, distinguishing these two subspecies by pelage color. Further systematic analyses using morphometric characters and other DNA markers are necessary to confirm the taxonomic status of M. s. quelpartis