Strength-limiting damage and defects of dental CAD/CAM full-contour zirconia ceramics.

OBJECTIVE: This study aimed to compare the four-point flexural strength of CAM-milled and sintered (as-sintered, AS) specimens with those of high-polished (HP) specimens using chairside polishing systems to simulate clinical surface conditions. METHODS: Seven full-contour zirconia CAM/CAM blanks with various yttria contents (3, 4, 5 mol%) including three high-translucent groups (5Y) were selected to prepare flexural specimens. The bend bar specimens (2.0 × 4.0 × 25.0 mm3) were fabricated by using STL file and dental CAM machine with the respective zirconia blanks (98 mm ϕ and 10-14 mm in height). Twelve bar specimens were machined from one zirconia puck and a total of 24 specimens were prepared from each group. The pre-sintered bar specimens were sintered by using a dental zirconia furnace at 1530-1550 °C for 2 h according to the instructions. All sintered specimens were divided into two groups: as-sintered (AS) group and high-polished (HP) groups (n = 12). HP groups were subjected to polishing one surface of specimens using a three-step polishing system and finally finished with diamond polishing. After cleaning and drying, the flexural strength of all specimens was determined by a fully articulating four-point flexure fixture consisting of a 1/4-point test configuration with an inner/outer span of 10/20 mm. Statistical differences between AS and HP groups were conducted with Weibull analysis. The fractured surfaces of zirconia specimens were observed using a field emission SEM and EDS to detect failure origins. RESULTS: The mean AS flexural strength values were significantly lower than those of HP counterparts. However, Weibull moduli expressing the reliability of HP groups were generally decreased although not significantly in comparison to their AS. The fracture of the AS specimens mostly originated from extrinsic CAM-milling defects, while the HP specimens were fractured from intrinsic subsurface or volume defects including pores, large grain clusters, inclusions, and corner-located critical flaws. Two high-translucent (5Y) zirconia groups were not affected in their strength and reliability after polishing, whereas one 5Y zirconia significantly increased its strength but significantly lowered its reliability. SIGNIFICANCE: The extrinsic and intrinsic strength-limiting defects should be considered in evaluating the flexural strength and reliability of dental CAD/CAM zirconia ceramics for full-contour restorations. For the materials tested in this study, more optimized processing of blanks and milling protocols of pre-sintered zirconia blanks should be developed including post-sintering surface finishing to reduce the flaw population regulating strength and reliability which will affect the survivability of dental zirconia prostheses.

High-Quality Genome Assembly of Peronospora destructor, the Causal Agent of Onion Downy Mildew.

Peronospora destructor is an obligate biotrophic oomycete that causes downy mildew on onion (Allium cepa). Onion is an important crop worldwide, but its production is affected by this pathogen. We sequenced the genome of P. destructor using the PacBio sequencing platform, and de novo assembly resulted in 74 contigs with a total contig size of 29.3 Mb and 48.48% GC content. Here, we report the first high-quality genome sequence of P. destructor and its comparison with the genome assemblies of other oomycetes. The genome is a very useful resource to serve as a reference for analysis of P. destructor isolates and for comparative genomic studies of the biotrophic oomycetes.

Whole-Genome Sequence of Erwinia persicina B64, Which Causes Pink Soft Rot in Onions.

Erwinia persicina B64 was isolated from rotten onions in cold-storage facilities. Here, we report the complete genome sequence of E. persicina B64, which contains 5,070,450 bp with 55.17% GC content. The genome of this isolate is composed of one chromosome and two plasmids.

Successful Treatment of Bleeding Duodenal Varix by Percutaneous Transsplenic Embolization.

Variceal bleeding occurs primarily in the esophagus or stomach in patients with liver cirrhosis, but can also occur rarely in the duodenum. Duodenal variceal bleeding has a high mortality and poor prognosis due to heavy blood flow originating from the portal vein (PV) and the technical difficulty of hemostatic procedures. Treatments including endoscopic sclerotherapy, endoscopic ligations, endoscopic clipping and transjugular intrahepatic portosystemic shunt have been tried, with only moderate and variable success. A percutaneous transsplenic approach offers another way of accessing the PV. Here we report a case of successfully treated duodenal variceal bleeding by percutaneous transsplenic embolization.

Austrian syndrome with a delayed onset of heart failure.

A 59-year-old man treated with pneumococcal meningitis 4 months ago was hospitalized for acute heart failure and performed aortic valve replacement by rupture of aortic valve. The frequent association of pneumococcal meningitis and endocarditis is known as Austrian syndrome. Though Austrian syndrome is a clinically rare disease, the evolution of pneumococcal endocarditis is very aggressive and associated with high mortality, and early recognition for evidence of endocardial lesion in patients with pneumococcal meningitis is important to reduce the complications and mortality rate.

Determination of cytoplasmic male sterile factors in onion plants (Allium cepa L.) using PCR-RFLP and SNP markers.

We have developed a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) marker that can distinguish male-fertile (N) and male-sterile (S) cytoplasm in onions. The PCR-RFLP marker was located in a chloroplast psbA gene amplicon. Digesting the amplicons from different cytoplasm-containing varieties with the restriction enzyme MspI revealed that N-cytoplasm plants have a functional MspI site (CCGG), whereas the S-cytoplasm plants has a substitution in that site (CTGG), and thus no MspI target. The results obtained using this PCR-RFLP marker to distinguish between cytoplasmic male sterile factors in 35 onion varieties corresponded with those using a CMS-specific sequence-characterized amplified region (SCAR) marker. Moreover, the PCR-RFLP marker can identify N- ot S-cytoplasms in DNA sample mixtures in which they are in up to a 10-fold minority, indicating that use of the marker has high diagnostic precision. We also demonstrated the usefulness of the SNP detected in the psbA gene for high-throughput discrimination of CMS factors using Real-time PCR and a TaqMan probe assay.

Enhanced degradation of 2,4,6-trinitrotoluene (TNT) in a soil column planted with Indian mallow (Abutilon avicennae).

Phytoremediation of soil contaminated with 2,4,6-trinitrotoluene (TNT) was studied by growing Indian mallow (Abutilon avicennae) in a soil column reactor with 2 kg of TNT contaminated soil (120 mgTNT/kg) in the top and 18 kg of uncontaminated soil in the bottom. After 50 d, TNT remaining in the column with Indian mallow was 23.2% of the initial TNT, while 48.1% of the initial TNT remained in the column without Indian mallow. In the TNT contaminated column, the growth of Indian mallow decreased by 32.4% in roots and 34.3% in shoots on a dry weight basis, respectively, compared to the uncontaminated column. However, critical symptoms such as chlorosis and leaf loss were not observed. Of the 76.8% of the TNT that disappeared in the planted column, less than 0.2% of initial TNT was recovered in the shoot and root extracts of Indian mallow. TNT transformation products in plants include unidentified polar intermediates and aminodinitrotoluenes. The results showed that planting Indian mallow in TNT contaminated soil enhanced TNT reduction both by stimulating microbial activity that enhances microbial TNT transformation, and by direct uptake and phytotransformation of TNT.