Tunable diameter and spacing of double Ge quantum dots using highly-controllable spacers and selective oxidation of SiGe.

We report the novel tunability of the diameters and spacings of paired Ge double quantum dots (DQDs) using nano-spacer technology in combination with selective oxidation of Si0.85Ge0.15 at high temperature. Pairs of spherical-shaped Ge QDs were formed by the selective oxidation of poly-SiGe spacer islands at each sidewall corner of the nano-patterned Si3N4/poly-Si ridges. The diameters of the Ge spherical QDs are essentially determined by geometrical conditions (height, width, and length) of the nano-patterned spacer islands of poly-SiGe, which are tunable by adjusting the process times of deposition and etch back for poly-SiGe spacer layers in combination with the exposure dose of electron-beam lithography. Most importantly, the separations between the Ge DQDs are controllable by adjusting the widths of the poly-Si/Si3N4 ridges and the thermal oxidation times. Our self-organization and self-alignment approach achieved high symmetry within the Ge DQDs in terms of the individual QD diameters as well as the coupling barriers between the QDs and external electrodes in close proximity.

Risk Factors for Prolonged Hospitalization in Pediatric Appendicitis Patients with Medical Treatment.

BACKGROUND: With effective antibiotics against enteric flora and computed tomography-guided drainage for abscesses, the initial use of nonoperative therapy for children with appendicitis has increased both in recent reports and at our hospital. However, it has been reported that these patients have a relatively longer hospital stay and that their treatment is more expensive than those who undergo aggressive surgical intervention. METHODS: This was a retrospective cohort study based in a single medical center. A systemic chart review was conducted to identify risk factors for prolonged hospitalization in pediatric appendicitis patients not initially undergoing surgical treatment. Patient demographics, clinical symptoms, duration of symptoms, laboratory findings, imaging findings, complications, and length of hospital stay were analyzed. Logistic regression analysis was used to identify significant predictors of prolonged hospitalization (≥15 days) and readmission. RESULTS: One hundred and twenty-five patients were recruited in this study, of whom 53 (42.4%) had prolonged hospitalization. The values of serum C-reactive protein (CRP) were significantly higher in patients with prolonged hospitalization compared with those without prolonged hospitalization (203 ± 108.6 mg/L vs. 140 ± 93.0 mg/L, p = 0.001). Risk factors of prolonged hospitalization were serum CRP >150 mg/L (35/53 vs. 28/72, p = 0.001), abscess formation (38/53 vs. 35/72, p = 0.008), and multiple abscesses (10/53 vs. 1/72, p = 0.001). Under multivariate analysis, CRP >150 mg/L (odds ratio=1.004, p = 0.0334) and multiple abscesses (odds ratio = 8.788, p = 0.044) were two independent predictors for prolonged hospitalization. CONCLUSION: Marked elevation of serum CRP (>150 mg/L) and multiple abscesses are two independent risk factors for prolonged hospitalization in children with appendicitis who are initially treated nonoperatively.

Highly efficient gel-state dye-sensitized solar cells prepared using poly(acrylonitrile-co-vinyl acetate) based polymer electrolytes.

Poly(acrylonitrile-co-vinyl acetate) (PAN-VA) is utilized as a gelation agent to prepare gel-state electrolytes for dye-sensitized solar cell (DSSC) applications. Based on the synergistic effect of PAN-VA and TiO(2) fillers in the electrolyte, the gel-state DSSC can achieve a conversion efficiency higher than that of a liquid counterpart. The high performance of the gel-electrolyte is attributed to the in situ gelation property of the gel-electrolyte, the contribution of the PAN-VA to the charge transfer, as well as the enhancement effect of TiO(2) fillers on the charge transfer at the Pt-electrolyte interface. The experimental results show that the efficiencies of the gel-state cells have little dependence on the conductivity of the electrolytes with various contents of PAN-VA, but are closely related to the penetration situation of the electrolyte in the TiO(2) film. For PAN-VA concentrations ≤15 wt%, the electrolyte can be easily injected at room temperature based on its in situ gelation property. For higher PAN-VA concentrations, good penetration of the high viscous electrolyte can be achieved by elevating the operation temperature. By utilizing a heteroleptic ruthenium dye (coded CYC-B11), gel-state DSSCs with an efficiency of above 10% are obtained. Acceleration tests show that the cell is stable under one-sun illumination at 60 °C.