Collapse-type shrinkage characteristics in plantation-grown eucalypts： I . Correlations of basic density and some structural indices with shrinkage and collapse properties

Collapse-type shrinkage is one of highly refractory drying defects inlow-medium density plantation-grown eucalypt wood used as solid wood products. Basic density (BD),microfibril angle (MFA), double fibre cell wall thickness (DWT), proportion of ray parenchyma (RP),unit cell wall shrinkage, total shrinkage and residual collapse, which are associated withcollapse-type shrinkage characteristics, were investigated by using simple regression method forthree species of collapse-susceptible Eucalyptus urophyll,, E. grandis and E. urophyllaxE.grandis,planted at Dong-Men Forest Farm in Guangxi autonomous region, China. The results indicated that:unit cell wall shrinkage had a extremely strong positive correlation with BD, moderately strongpositive correlation with DWT, and a weakly or moderately negative correlation with RP and MFA;total shrinkage was positively correlated with BD, DWT and RP and negatively related to MFA, but notable to be predicted ideally by any examined factors alone owing to lower R^2 value (R^2≤0.5712);residual collapse was negatively correlated with BD and DWT, linearly positively correlated withMFA, and had strongly positive linear correlation with RP. It is concluded that BD can be used assingle factor (R^2≥ 0.9412) to predicate unit cell wall shrinkage and RP is the relatively soundindicator for predicting residual collapse

Endoscopic treatment of periampullary duodenal duplication cysts in children: Four case reports and review of the literature

BACKGROUND Duodenal duplications are rare congenital anomalies of the gastrointestinal tract.As the periampullary variant is much rarer,literature is scant and only few authors have reported their experience in diagnosis and treatment,particularly with operative endoscopy.CASE SUMARY To report our experience with the endoscopic treatment in a series of children with periampullary duodenal duplication cysts,focusing on the importance of obtaining an accurate preoperative anatomic assessment of the malformations.The pediatric periampullary duodenal duplication cyst literature is reviewed.We conducted a systematic review according to the PRISMA guidelines.The PubMed database was searched for original studies on“duodenal duplication”,“periampullary duplication”or“endoscopic management”published since 1990,involving patients younger than 18 years of age.Eligible study designs were case report,case series and reviews.We analyzed the data and reported the results in table and text.Fifteen eligible articles met the inclusion criteria with 16 patients,and analysis was extended to our additional 4 cases.Median age at diagnosis was 13.5 years.Endoscopic treatment was performed in 10(50%)patients,with only 2 registered complications.CONCLUSION Periampullary duodenal duplication cysts in pediatric patients are very rare.Our experience suggests that an accurate preoperative assessment is critical.In the presence of sludge or stones inside the duplication,endoscopic retrograde cholangio-pancreatography is mandatory to demonstrate a communication with the biliary tree.Endoscopic treatment resulted in a safe,minimally invasive and effective treatment.In periampullary duodenal duplication cyst endoscopically treated children,long-term follow-up is still necessary considering the potential malignant transformation at the duplication site.

Numerical simulation of broken pin effects on the flow field and cooling performance of a double-wall cooling configuration

In this paper, the flow characteristics of the double wall structure are presented and the effect of the broken pin size on the cooling performance and flow field of the double wall configuration is investigated. A periodic plate model with seven units is adopted, and there are an impingement hole and a film hole in each unit. Under five blowing ratios, six different sizes of the broken pin are compared, and the double wall configuration without broken pins is taken as the baseline.The results show that if the broken pins height is too small, the cooling effectiveness usually cannot be improved. With the presence of broken pins with a height of more than 0.4, the effectiveness is improved due to the enhancement of reattachment and recirculation of coolant. With the increase of the broken pin height, the cooling effectiveness increases. However, the increase of the diameter does not always improve the cooling performance, since the limiting effect of the wall jet. In this study, Case 6 with the largest broken pin always has the best cooling performance, but also the largest flow resistance. In Case 6 temperature is reduced by almost 15 K compared to the baseline, and more areas have relatively higher cooling effectiveness.