Enhanced Electrochemical Properties of Non-stoichiometric Layered Perovskites, Sm1-xBaCo2O5+d, for IT-SOFC Cathodes.

In this study, electrochemical properties of layered perovskites having non-stoichiometric compositions (Sm1-xBaCo2O5+d, x = 0, 0. 01, 0.02, 0.03, 0.04, 0.05, 0.10, and 0.15) were analyzed for the direct application of cathode materials for Intermediate Temperature-operating Solid Oxide Fuel Cells (IT-SOFC). From the Sm1-xBaCo2O5+d oxide systems calcined at 1,100°C for 8 h, single phase (SmBaCo2O5+d, SBCO_1) was maintained only in the case of the x = 0 composition. In the compositions of x = 0.05-0.10, BaCoO2.6 was mixed with the pattern of SBCO. In addition, in the composition of x = 0.15, it was confirmed that BaCoO2.6 and CoO phases coexisted with SBCO. In the compositions of Sm1-xBaCo2O5+d, the overall Area Specific Resistance (ASR) values decreased as the removal amount of Sm increased from x = 0-0.10; then, the values increased for compositions from x = 0.15. For example, the ASRs of SBCO_1, Sm0.95BaCo2O5+d (SBCO_0.95), Sm0.90BaCo2O5+d (SBCO_0.90), and Sm0.85BaCo2O5+d (SBCO_0.85) measured at 600°C were 0.301, 0.147, 0.119, and 0.179 Ω cm2, respectively. In particular, SBCO_0.90 was found to have an excellent ASR property of about 0.035 Ω cm2 at 700°C. Typical properties of the metal-insulator transition (MIT) electrical conductivity were shown in all measured compositions. The temperature at which MIT occurred increased as the non-stoichiometric composition increased.

SmBa1-xCaxCo2O5+d Layered Perovskite Cathodes for Intermediate Temperature-operating Solid Oxide Fuel Cells.

In SmBa1-xCaxCo2O5+d (x = 0.01, 0.03, 0.1, and 0.2, SBCCO) oxide systems calcined at 1100°C for 8 h, the XRD patterns of the SBCCO single phase were maintained in the cases of SmBa0.97Ca0.03Co2O5+d (SBCCO-0.97) and SmBa0.99Ca0.01Co2O5+d (SBCCO-0.99) compositions. In SmBa0.8Ca0.2Co2O5+d (SBCCO-0.8) and SmBa0.9Ca0.1Co2O5+d (SBCCO-0.9), CaCoSmO4 existed with the pattern SBCCO. SBCCO structures were identified as orthorhombic crystal structures because they showed splitting of the X-ray diffraction (XRD) peaks at 23.4°, 47.9°, and 59.1°.Typical metallic conduction behaviors were found in all measured compositions except SBCCO-0.8, which showed a metal-insulator transition (MIT) behavior. Compared to other SmBa1-xCaxCo2O5+d compositions, SBCCO-0.8 showed the highest electrical conductivity of 460 S/cm at 500°C. In particular, SBCCO-0.9 was found to have an excellent ASR characteristic of about 0.077 Ωcm2 at 700°C. The activation energy of SBCCO-0.9 was the lowest among SBCCO oxide systems with a value of 0.77 eV.

Oscillatory bursting of gel fuel droplets in a reacting environment.

Understanding the combustion behavior of gel fuel droplets is pivotal for enhancing burn rates, lowering ignition delay and improving the operational performance of next-generation propulsion systems. Vapor jetting in burning gel fuel droplets is a crucial process that enables an effective transport (convectively) of unreacted fuel from the droplet domain to the flame zone and accelerates the gas-phase mixing process. Here, first we show that the combusting ethanol gel droplets (organic gellant laden) exhibit a new oscillatory jetting mode due to aperiodic bursting of the droplet shell. Second, we show how the initial gellant loading rate (GLR) leads to a distinct shell formation which self-tunes temporally to burst the droplet at different frequencies. Particularly, a weak-flexible shell is formed at low GLR that undergoes successive rupture cascades occurring in same region of the droplet. This region weakens due to repeated ruptures and causes droplet bursting at progressively higher frequencies. Contrarily, high GLRs facilitate a strong-rigid shell formation where consecutive cascades occur at scattered locations across the droplet surface. This leads to droplet bursting at random frequencies. This method of modulating jetting frequency would enable an effective control of droplet trajectory and local fuel-oxidizer ratio in any gel-spray based energy formulation.

Effect of core quantum-dot size on power-conversion-efficiency for silicon solar-cells implementing energy-down-shift using CdSe/ZnS core/shell quantum dots.

Silicon solar cells mainly absorb visible light, although the sun emits ultraviolet (UV), visible, and infrared light. Because the surface reflectance of a textured surface with SiNX film on a silicon solar cell in the UV wavelength region (250-450 nm) is higher than ∼27%, silicon solar-cells cannot effectively convert UV light into photo-voltaic power. We implemented the concept of energy-down-shift using CdSe/ZnS core/shell quantum-dots (QDs) on p-type silicon solar-cells to absorb more UV light. CdSe/ZnS core/shell QDs demonstrated clear evidence of energy-down-shift, which absorbed UV light and emitted green-light photoluminescence signals at a wavelength of 542 nm. The implementation of 0.2 wt% (8.8 nm QDs layer) green-light emitting CdSe/ZnS core/shell QDs reduced the surface reflectance of the textured surface with SiNX film on a silicon solar-cell from 27% to 15% and enhanced the external quantum efficiency (EQE) of silicon solar-cells to around 30% in the UV wavelength region, thereby enhancing the power conversion efficiency (PCE) for p-type silicon solar-cells by 5.5%.

The energy-down-shift effect of Cd(0.5)Zn(0.5)S-ZnS core-shell quantum dots on power-conversion-efficiency enhancement in silicon solar cells.

We found that Cd0.5Zn0.5S-ZnS core (4.2 nm in diameter)-shell (1.2 nm in thickness) quantum dots (QDs) demonstrated a typical energy-down-shift (2.76-4.96 → 2.81 eV), which absorb ultra-violet (UV) light (250-450 nm in wavelength) and emit blue visible light (∼442 nm in wavelength). They showed the quantum yield of ∼80% and their coating on the SiNX film textured p-type silicon solar-cells enhanced the external-quantum-efficiency (EQE) of ∼30% at 300-450 nm in wavelength, thereby enhancing the short-circuit-current-density (JSC) of ∼2.23 mA cm(-2) and the power-conversion-efficiency (PCE) of ∼1.08% (relatively ∼6.04% increase compared with the reference without QDs for p-type silicon solar-cells). In particular, the PCE peaked at a specific coating thickness of the Cd0.5Zn0.5S-ZnS core-shell QD layer; i.e., the 1.08% PCE enhancement at the 8.8 nm thick QD layer.

Intradural schwannoma complicated by lumbar disc herniation at the same level: A case report and review of the literature.

Intradural tumours of the spine are usually benign and have a good prognosis, if they are diagnosed and removed early. Lumbar disc herniation is a common cause of chronic, acute, or recurrent lumbar radiculopathy. However, to date, there have been no reports of progressive neurological deficiencies due to the co-existence of two significant pathologies contributing to intradural and extradural compression. The current study reports the rare case of a patient with simultaneous extradural and intradural compression of the nerve root due to co-existent intervertebral disc herniation and an intradural schwannoma at the same level. A 71-year-old female suffering from lower back pain and radiating pain of the right lower extremities was admitted to Busan Korea Hospital (Busan, Korea). Magnetic resonance imaging revealed lumbar disc herniation at L4-5 and a mass occupying the intradural space at the same level of the compressed dural sac. Using the posterior approach, surgical excision of the two pathologies was performed. Pathological diagnosis confirmed schwannoma and the symptoms markedly improved.

Preoperative computer-based simulations for the correction of kyphotic deformities in ankylosing spondylitis patients.

BACKGROUND CONTEXT: A preoperative plan is important to obtain appropriate balance of the sagittal plane in patients with kyphotic deformity. Previous methods to calculate the correction angle are inconvenient and complicated, whereas the method using computer simulations may be very effective and much simpler than existing methods. PURPOSE: To evaluate the efficacy of preoperative measurements using a computer simulation for corrective osteotomy for the surgical treatment of kyphosis caused by ankylosing spondylitis (AS). STUDY DESIGN: Retrospective clinical data analysis. PATIENT SAMPLE: The sample comprises 18 AS patients with fixed kyphotic deformity who underwent corrective osteotomies at our hospital between October 2007 and January 2010. OUTCOME MEASURES: Thoracic kyphosis, lumbar lordosis, and the sagittal vertical axis (SVA) of the spine were evaluated by preoperative computer simulation and radiologic measurement. Clinical assessments were performed according to the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Short Form-36 (SF-36), and EuroQol-5 dimension (EQ-5D) before and after the surgery. METHODS: The coincidence between the preoperative computer simulation and postoperative radiologic parameters was evaluated. We also analyzed the changes derived from each clinical and radiologic measurement before and after the surgery. RESULTS: Mean thoracic kyphosis changed from 32.4° to 31.9°, mean lumbar lordosis was corrected from 11.5° to 26.9°, and the SVA was improved from 125.7 to 65.1 mm after surgery (p<.001). The correlation coefficients within groups between the computer simulations and radiologic parameters were 0.9, 0.6, and 0.7, showing significant congruency. Although BASDAI and BASFI did not significantly differ (p=.53 and p=.45, respectively), SF-36 and EQ-5D were significantly increased (p<.05 and p<.001, respectively). CONCLUSIONS: Comparisons of preoperative simulations and actual surgical outcomes showed significant coincidences; thus, evaluations through computer simulations before surgery are expected to help predict the level of correction possible after surgery and improve surgical planning.

Spinal osteotomy in ankylosing spondylitis: radiological, clinical, and psychological results.

BACKGROUND CONTEXT: Little is known about the psychological status in patients with ankylosing spondylitis (AS) before and after correction of fixed sagittal imbalance. PURPOSE: The aim of this study was to evaluate the changes in patients' psychological status after surgical correction and the existence of a correlation between psychological state and the angle of correction. STUDY DESIGN: A retrospective study was performed to assess radiological and clinical results, and psychological status in patients with AS with fixed kyphotic deformity. PATIENT SAMPLE: The sample comprises 24 patients with AS with fixed sagittal imbalance who underwent one-stage corrective osteotomies at our hospital between March 2006 and May 2010. All of the patients included in this study demonstrated an inability to look straight forward because of severe kyphotic deformities. OUTCOME MEASURE: The radiologic analysis included evaluation of thoracic kyphosis, lumbar lordosis, and the sagittal vertical axis (SVA) of the spine. Clinical assessments were performed with Short Form 36 (SF-36), the Bath Ankylosing Spondylitis Function Index (BASFI), and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). Patient psychological status was assessed using the Hospital Anxiety and Depression Questionnaire (HADS) and the Health Locus of Control-Form C Questionnaire (HLC-C). METHODS: Each of the above measurements was recorded before and 1 year after the surgery. The changes derived from each measurement before and after the surgery were evaluated. We also analyze the correlations among the radiological, clinical, psychological, and mental evaluations. RESULTS: Mean thoracic kyphosis changed from 38.5° to 33.3°. Mean lumbar lordosis was corrected from 13.8° to 26.1°, and the SVA was improved from 110.8 mm to 49.7 mm. There was significant improvement in the SF-36, BASDAI, BASFI, HADS, and HLC-C scores. The SVA changes were closely linked to BASFI and psychological status, especially anxiety and depression. CONCLUSIONS: The scores of disease status, general health, and psychological status were improved significantly after correction of kyphotic deformity. And the correction of sagittal imbalance was correlated significantly with anxiety and depression.

The effect of zoledronic acid on the volume of the fusion-mass in lumbar spinal fusion.

BACKGROUND: Few studies have explored the effects of bisphosphonates on bony healing in patients undergoing spinal fusion surgery. Most previous studies used animal models and found that bisphosphonate shows negative effects on spinal fusion consolidation. We intended to evaluate the effect of a single-dose of zoledronic acid on the volume of the fusion-mass in lumbar spinal fusion. METHODS: A retrospective review was carried out on 44 patients with symptomatic degenerative lumbar spinal stenosis who underwent one or two-level posterolateral fusion from January 2008 and January 2011. They were divided into 4 groups: group 1, autograft and zoledronic acid; group 2, allograft and zoledronic acid; group 3, autograft alone; and group 4, allograft alone. Functional radiography and three-dimensional computed tomography scans were used to evaluate and quantify the volume of the fusion-mass. The visual analog scale (VAS), the Oswestry disability index (ODI), and the short form 36 (SF-36) were used to evaluate the clinical outcomes. RESULTS: The mean volume of the fusion-mass per level was 8,814 mm(3), 8,035 mm(3), 8,383 mm(3), and 7,550 mm(3) in groups 1, 2, 3, and 4, respectively, but there were no significant differences between the groups (p = 0.829). There were no significant decreases in the volume of the fusion-mass (p = 0.533) in the zoledronic acid groups (groups 1 and 2). The VAS, the ODI, and the SF-36 at the 6-month follow-up after surgery were not significantly different (p > 0.05) among the 4 groups. The VAS, the ODI, and the SF-36 were not correlated with the volume of the fusion-mass (p = 0.120, 0.609, 0.642). CONCLUSIONS: A single dose of zoledronic acid does not decrease the volume of the fusion-mass in patients undergoing spinal fusion with osteoporosis. Therefore, we recommend that zoledronic acid may be used after spinal fusion in osteoporotic patients.

Lumbosacral fixation using the diagonal S2 screw for long fusion in degenerative lumbar deformity: technical note involving 13 cases.

Placing instrumentation into the ilium has been shown to increase the biomechanical stability and the fusion rates, but it has some disadvantages. The diagonal S2 screw technique is an attractive surgical procedure for degenerative lumbar deformity. Between 2008 and 2010, we carried out long fusion across the lumbosacral junction in 13 patients with a degenerative lumbar deformity using the diagonal S2 screws. In 12 of these 13 patients, the lumbosacral fusion was graded as solid fusion with obvious bridging bone (92%). One patient had a rod dislodge at one S2 screw and breakage of one S1 screw and underwent revision nine months postoperatively. So, we present alternative method of lumbopelvic fixation for long fusion in degenerative lumbar deformity using diagonal S2 screw instead of iliac screw.

The analysis of spinopelvic parameters and stability following long fusions with S1, S2 or iliac fixation.

PURPOSE: The purpose of this study was to analyse changes of spinopelvic parameters and stability in the treatment of degenerative lumbar deformity. METHODS: A retrospective review was carried out on 70 cases of degenerative lumbar deformity treated by long fusion with uni-cortical S1 fixation alone (US1F group, n = 20), bi-cortical S1 fixation alone (BS1F group, n = 20), additional diagonal S2 fixation (DS2F group, n = 14), and additional iliac fixation (ILF group, n = 16) from July 2003 to April 2010. The sagittal vertical axis (SVA), lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), and stability were used to evaluate radiologic outcomes. The clinical outcome was evaluated using the Oswestry Disability Index (ODI). RESULTS: In all groups, the LL was significantly increased at three months (p < 0.05). The PI and the SS of ILF patients significantly increased at three months (p < 0.05), while none of these values changed over time in non-ILF patients. The PT did not change postoperatively in any groups. The LL, SS, and PI were significantly greater in the ILF group at three months postoperatively and later (p < 0.05). DS2F and ILF had statistically significant stability compared to US1F and BS1F (p < 0.05). The ODI scores were significantly improved after surgery in all groups compared to before surgery (p < 0.05). CONCLUSIONS: Patients who had ILF in long fusion for the treatment of degenerative lumbar deformity had significant restoration of spinopelvic parameters compared to the other groups. In addition, DS2F and ILF provided more stability of distal instruments.

Management of tibial bony defect with metal block in primary total knee replacement arthroplasty.

PURPOSE: To analyze minimum 2-year clinical and radiological follow-up results of primary total knee replacement arthroplasty (TKRA) with metal block augmentation for tibial bony defect. MATERIALS AND METHODS: We analyzed 67 cases (52 patients) of primary TKRA with metal block augmentation for tibial bony defects from March 1999 and March 2008. Clinical results were evaluated using the Knee Society clinical rating system and the Western Ontario and McMaster University (WOMAC) score. Radiologic results were evaluated using the Knee Society roentgenographic evaluation system. RESULTS: The mean knee score and function score improved from 42.0 and 45.6 preoperatively to 94.5 and 85.4 postoperatively. At last follow-up, the mean WOMAC score was 16.8. The incidence of radiolucent lines was 10% (7 cases) during the follow-up period, but there was no case of progression. There were no statistically significant differences between the groups divided according to the block size (below 5 mm and over 8 mm) and between the stem and no-stem groups for all parameters. CONCLUSIONS: Primary TKRA with a metal block produced satisfactory results for the minimum 2-year follow-up and can be considered as a simple and effective method for the treatment of tibial bony defect in primary TKRA.

Management of sacral fractures associated with spinal or pelvic ring injury.

BACKGROUND: The proper treatment of sacral fracture has yet to be standardized. METHODS: Seventy-one patients with sacral fractures who were treated from December 2001 to January 2009 were evaluated. Classification was made depending on the presence of a combined injury in the spine or pelvic ring, displacement of the sacral fracture, and fracture location with surgical indications in case of a displaced fracture or neurologic injury. The surgical procedure used was either spinopelvic fixation with iliac screws or percutaneous iliosacral screw fixation. Fracture causes, treatments, classifications, the availability of the radiologic bony union and its application period, and clinical results using the Oswestry Disability Index were evaluated. RESULTS: There were 7 patients with isolated sacral fractures, 3 patients with sacral fractures that were combined with spinal injuries, 34 patients with sacral fractures with pelvic ring injuries, and 27 cases with both spinal and pelvic ring injuries. Among these, 11 patients also showed a neurologic deficit. Of the 26 patients who were indicated for surgical treatment, 23 achieved a bony union showing favorable clinical results; however, of the three patients who were not able to undergo operation, two showed a nonunion with bad clinical results including neurologic symptoms. CONCLUSION: Sacral fracture often accompanies spinal or pelvic ring injuries. Depending on the presence of spinopelvic dissociation, spinopelvic fixation is recommended for cases with dissociation, and percutaneous iliosacral screw fixation is recommended for cases without dissociation. LEVEL OF EVIDENCE: Therapeutic study, level IV.

The rare case of giant cell tumor occuring in the axial skeleton after 15 years of follow-up: Case report.

The majority of giant cell tumors (GCTs) occur in the ends of the long bones. The presence of more than one GCT in the axial skeleton is rare. A GCT is capable of remaining clinically latent following treatment and becoming active a number of years later. We report an extremely rare case of GCT occurring in the axial skeleton, involving the sacrum, thoracic spine and parieto-occipital skull in more than 15 years of follow-up.