Fracture Toughness of Silicate Glasses: Insights from Molecular Dynamics Simulations

Understanding, predicting and eventually improving the resistance to fracture of silicate materials is of primary importance to design new glasses that would be tougher, while retaining their transparency. However, the atomic mechanism of the fracture in amorphous silicate materials is still a topic of debate. In particular, there is some controversy about the existence of ductility at the nano-scale during the crack propagation. Here, we present simulations of the fracture of three archetypical silicate glasses using molecular dynamics. We show that the methodology that is used provide realistic values of fracture energy and toughness. In addition, the simulations clearly suggest that silicate glasses can show different degrees of ductility, depending on their composition.Comment: arXiv admin note: text overlap with arXiv:1410.291

Glutamate Receptors GluR1 and GluR4 in the Hamster Superior Colliculus: Distribution and Co-localization with Calcium-Binding Proteins and GABA

We investigated the distributions of AMPA glutamate receptor subtypes GluR1 and GluR4 in the hamster superior colliculus (SC) with antibody immunocytochemistry and the effect of enucleation on these distributions. We compared these labelings to those of GluR2/3 in our previous report (Park et al., 2004, Neurosci Res., 49:139–155) and calcium-binding proteins calbindin D28K, calretinin, parvalbumin, and GABA. Anti-GluR1-immunoreactive (IR) cells were scattered throughout the SC. By contrast, anti-GluR4-IR cells formed distinct clusters within the lower lateral stratum griseum intermediale (SGI) and lateral stratum album intermediale (SAI). The GluR1- and GluR4-IR neurons varied in size and morphology. The average diameter of the GluR1-IR cells was 13.00 µm, while the GluR4-IR cells was 20.00 µm. The large majority of IR neurons were round or oval cells, but they also included stellate, vertical fusiform and horizontal cells. Monocular enucleation appeared to have no effect on the GluR1 and GluR4 immunoreactivity. Some GluR1-IR cells expressed calbindin D28K (9.50%), calretinin (6.59%), parvalbumin (2.53%), and GABA (20.54%). By contrast, no GluR4-IR cells expressed calcium-binding proteins or GABA. Although the function of the AMPA receptor subunits in SC is not yet clear, the distinct segregation of the GluR subunits, its differential colocalization with calcium-binding proteins and GABA, and differential responses to enucleation suggest the functional diversity of the receptor subunits in visuo-motor integration in the SC

Selenoprotein W enhances skeletal muscle differentiation by inhibiting TAZ binding to 14-3-3 protein

AbstractSelenoprotein W (SelW) is expressed in various tissues, particularly in skeletal muscle. We have previously reported that SelW is up-regulated during C2C12 skeletal muscle differentiation and inhibits binding of 14-3-3 to its target proteins. 14-3-3 reduces myogenic differentiation by inhibiting nuclear translocation of transcriptional co-activator with PDZ-binding motif (TAZ). Phosphorylation of TAZ at Ser89 is required for binding to 14-3-3, leading to cytoplasmic retention of TAZ and a delay in myogenic differentiation. Here, we show that myogenic differentiation was delayed in SelW-knockdown C2C12 cells. Down-regulation of SelW also increased TAZ binding to 14-3-3, which eventually resulted in decreasing translocation of TAZ to the nucleus. However, phosphorylation of TAZ at Ser89 was not affected. Although phosphorylation of TAZ at Ser89 was sustained by the phosphatase inhibitor okadaic acid, nuclear translocation of TAZ was increased by ectopic expression of SelW. This result was due to decreased binding of TAZ to 14-3-3. We also found that the interaction between TAZ and MyoD was increased by ectopic expression of SelW. Taken together, these findings strongly demonstrate that SelW enhances C2C12 cell differentiation by inhibiting TAZ binding to 14-3-3

A SNP Harvester Analysis to Better Detect SNPs of CCDC158 Gene That Are Associated with Carcass Quality Traits in Hanwoo

The purpose of this study was to investigate interaction effects of genes using a Harvester method. A sample of Korean cattle, Hanwoo (n = 476) was chosen from the National Livestock Research Institute of Korea that were sired by 50 Korean proven bulls. The steers were born between the spring of 1998 and the autumn of 2002 and reared under a progeny-testing program at the Daekwanryeong and Namwon branches of NLRI. The steers were slaughtered at approximately 24 months of age and carcass quality traits were measured. A SNP Harvester method was applied with a support vector machine (SVM) to detect significant SNPs in the CCDC158 gene and interaction effects between the SNPs that were associated with average daily gains, cold carcass weight, longissimus dorsi muscle area, and marbling scores. The statistical significance of the major SNP combinations was evaluated with x2-statistics. The genotype combinations of three SNPs, g.34425+102 A>T(AA), g.4102636T>G(GT), and g.11614+19G>T(GG) had a greater effect than the rest of SNP combinations, e.g. 0.82 vs. 0.75 kg, 343 vs. 314 kg, 80.4 vs 74.7 cm2, and 7.35 vs. 5.01, for the four respective traits (p<0.001). Also, the estimates were greater compared with single SNPs analyzed (the greatest estimates were 0.76 kg, 320 kg, 75.5 cm2, and 5.31, respectively). This result suggests that the SNP Harvester method is a good option when multiple SNPs and interaction effects are tested. The significant SNPs could be applied to improve meat quality of Hanwoo via marker-assisted selection

Reorganization of Photoreceptor Layer on Optical Coherence Tomography Concurrent with Visual Improvement after Macular Hole Surgery

To report three cases in which reorganization of the photoreceptor layer on optical coherence tomography (OCT) was concurrent with long-term visual recovery after macular hole surgery. Serial OCT scans of three eyes in which visual acuity continued to improve for 1 or more years after successful macular hole surgery were reviewed. Case 1. At postoperative four weeks, visual acuity was 20/100 with disorganized photoreceptor layer on OCT. The photoreceptor layer had been reorganized and visual acuity had improved to 20/25 by 1 year. Case 2. Two weeks after the operation, visual acuity was 20/125 and disorganization of the photoreceptor layer was noted. Visual acuity improved to 20/50 by four months. The photoreceptor layer had been partly reorganized and had appearance of a broken line. Visual acuity had improved to 20/40 and the photoreceptor layer had been reorganized further with a residual defect on OCT by 15 months. Case 3. Visual acuity at two weeks was 20/100. OCT revealed disorganization of the photoreceptor layer. Six months after the operation, the partly reorganized photoreceptor layer appeared as a broken line and visual acuity had reached 20/80. Visual acuity had improved further to 20/40 by 1 year, concurrent with improved organization of the photoreceptor layer. The reorganization of the photoreceptor layer plays a part in long-term improvement of visual acuity after macular hole surgery

Calcium-binding Protein Calretinin Immunoreactivity in the Dog Superior Colliculus

We studied calretinin-immunoreactive (IR) fibers and cells in the canine superior colliculus (SC) and studied the distribution and effect of enucleation on the distribution of this protein. Localization of calretinin was immunocytochemically observed. A dense plexus of anti-­calretinin-IR fibers was found within the upper part of the superficial gray layer (SGL). Almost all of the labeled fibers were small in diameter with few varicosities. The intermediate and deep layers contained many calretinin-IR neurons. Labeled neurons within the intermediate gray layer (IGL) formed clusters in many sections. By contrast, labeled neurons in the deep gray layer (DGL) did not form clusters. Calretinin-IR neurons in the IGL and DGL varied in morphology and included round/oval, vertical fusiform, stellate, and horizontal neurons. Neurons with varicose dendrites were also labeled in the IGL. Most of the labeled neurons were small to medium in size. Monocular enucleation produced an almost complete reduction of calretinin-IR fibers in the SC contralateral to the enucleation. However, many calretinin-IR cells appeared in the contralateral superficial SC. Enucleation appeared to have no effect on the distribution of calretinin-IR neurons in the contralateral intermediate and deep layers of the SC. The calretinin-IR neurons in the superficial dog SC were heterogeneous small- to medium-sized neurons including round/oval, vertical fusiform, stellate, pyriform, and ­horizontal in shape. Two-color immunofluorescence revealed that no cells in the dog SC ­expressed both calretinin and GABA. Many horseradish peroxidase (HRP)-labeled retinal ganglion cells were seen after injections into the superficial layers. The vast majority of the double-labeled cells (HRP and calretinin) were small cells. The present results indicate that antibody to calretinin labels subpopulations of neurons in the dog SC, which do not express GABA. The results also suggest that the calretinin-IR afferents in the superficial layers of the dog SC originate from small class retinal ganglion cells. The expression of calretinin might be changed by the cellular activity of selective superficial collicular neurons. These results are valuable in delineating the basic neurochemical architecture of the dog visual system

Broken Guidewire Fragment in the Radio-brachial Artery During Transradial Sheath Placement: Percutaneous Retrieval via Femoral Approach

A case in which a 0.014" wire was broken during the sheath placement in the radial artery for transradial coronary procedure is described here, and a successful retrieval of it using conventional methods is also described. Through the left femoral artery, the 6 Fr guiding catheter was advanced down to the tip of the broken wire at the brachial artery, and the distal part of the broken guidewire was captivated into the guiding catheter. By inflating the balloon catheter inside of the guiding catheter, seized broken guidewire between the inflated balloon and the guiding catheter was removed successfully by withdrawing the whole system en bloc