Search

In perovskite solar cells, the interfaces between the perovskite and charge-transporting layers contain high concentrations of defects (about 100 times that within the perovskite layer), specifically, deep-level defects, which substantially reduce the power conversion efficiency of the devices1–3. Recent efforts to reduce these interfacial defects have focused mainly on surface passivation4–6. However, passivating the perovskite surface that interfaces with the electron-transporting layer is difficult, because the surface-treatment agents on the electron-transporting layer may dissolve while coating the perovskite thin film. Alternatively, interfacial defects may not be a concern if a coherent interface could be formed between the electron-transporting and perovskite layers. Here we report the formation of an interlayer between a SnO2 electron-transporting layer and a halide perovskite light-absorbing layer, achieved by coupling Cl-bonded SnO2 with a Cl-containing perovskite precursor. This interlayer has atomically coherent features, which enhance charge extraction and transport from the perovskite layer, and fewer interfacial defects. The existence of such a coherent interlayer allowed us to fabricate perovskite solar cells with a power conversion efficiency of 25.8 per cent (certified 25.5 per cent)under standard illumination. Furthermore, unencapsulated devices maintained about 90 per cent of their initial efficiency even after continuous light exposure for 500 hours. Our findings provide guidelines for designing defect-minimizing interfaces between metal halide perovskites and electron-transporting layers. An atomically coherent interlayer between the electron-transporting and perovskite layers in perovskite solar cells enhances charge extraction and transport from the perovskite, enabling high power conversion efficiency.

Formamidinium lead triiodide (FAPbI3) perovskite solar cells (PSCs) are mainly fabricated by sequentially coating lead iodide and formamidinium iodide, or by coating a solution in which all components are dissolved in one solvent (one-pot process). The PSCs produced by both processes exhibited similar efficiencies; however, their long-term stabilities were notably different. We concluded that the major reason for this behaviour is the stabilization of the α-FAPbI3 phase by isopropylammonium cations produced by the chemical reaction between isopropyl alcohol, used as solvent, and methylammonium chloride, added during the process. On this basis, we fabricated PSCs by adding isopropylammonium chloride to the perovskite precursor solution for the one-pot process and achieved a certified power conversion efficiency of 23.9%. Long-term operational current density–voltage measurements (one sweep every 84 min under 1-Sun irradiation in nitrogen atmosphere) showed that the as-fabricated device with an initial efficiency of approximately 20% recorded an efficiency of about 23% after 1,000 h that gradually degraded to about 22% after an additional 1,000 h. The operational stability of formamidinium lead triiodide solar cells varies with the fabrication method of the perovskite layer. Now Park et al. find that isopropylammonium stabilizes the perovskite structure and leads to solar cells with 2,000-h stability under constant illumination.

This study aimed to evaluate the optimal dosage of topical tranexamic acid (TXA) considering the efficacy and safety for controlling bleeding after total knee arthroplasty (TKA). This prospective randomized double-blinded placebo-controlled comparative study included 325 patients scheduled to undergo TKA, who were randomly assigned to five groups based on the topical TXA injection (n = 65 per group): control; group 1, 0.5 g TXA; group 2, 1.0 g TXA; group 3, 2.0 g TXA; and group 4, 3.0 g TXA. The primary outcome was decrease in postoperative hemoglobin levels. The secondary outcomes were blood loss calculated using Good’s method, drainage volume, frequency of transfusion, and range of motion (ROM). Plasma TXA levels and complications were also evaluated. Significant differences were noted in the decrease in hemoglobin levels between the control group and groups 2 (p = 0.0027), 3 (p = 0.005), and 4 (p = 0.001). No significant differences were shown among the experimental groups. Significant differences in total blood loss and frequency of transfusion were noted between the control group and groups 2 (p = 0.004, 0.002, respectively), 3 (p = 0.007, 0.001, respectively), and 4 (p = 0.001, 0.009, respectively) without showing significant differences among the experimental groups. With respect to drainage volume, no significant differences were observed among the groups. The serum TXA levels increased proportionally with the applied dose of topical TXA immediately and at 3 and 6 h postoperatively. Symptomatic deep vein thrombosis or pulmonary embolism was not observed in any group. Other complications related to TXA administration were not detected. Topical application of 1.0 g or more of TXA shows significant bleeding control without a dose–response relationship. Blood TXA levels increase with the TXA dose following topical TXA application. Therefore, to prevent overdosing and reduce potential complications with ensuring the effectiveness, 1.0 g of TXA is recommended as a topical application. I.

For the practical application of perovskite solar cells (PSC), it is desirable to have high efficiency, long-term stability, and low manufacturing cost. Therefore, it is required to develop inexpensive and well-performing hole-transporting materials (HTMs). In this study, we synthesized SFXDAnCBZ, which is a new carbazole-based spiro[fluorene-9,9'-xanthene] (SFX) derivative, where the central core and end-cap units consist of SFX and N3,N6-bis(di-4-anisylamino)-9H-carbazole (DAnCBZ), respectively, as an efficient and low-cost HTM for PSCs. Photoluminescence quenching at the SFXDAnCBZ/perovskite interface was more effective than at the perovskite/Spiro-OMeTAD (2,2',7,7'-tetrakis-(N,N-di-p-methoxy-phenyl-amine) 9,9'spiro-bifluorene) interface. We fabricated a PSC with a power conversion efficiency (PCE) of 20.87% under 1 sun illumination (100 mW cm-2) using SFXDAnCBZ as an HTM. This value is comparable to that measured for the benchmark Spiro-OMeTAD. Thus, this result confirms that SFX core-based materials can be a new kind of HTMs for high-efficiency and low-cost PSCs.

In perovskite solar cells, the interfaces between the perovskite and charge-transporting layers contain high concentrations of defects (about 100 times that within the perovskite layer), specifically, deep-level defects, which substantially reduce the power conversion efficiency of the devices

Expectation for renewable energy is increasing due to environmental pollution such as fossil fuel depletion, CO2 emission, and harmful gases. Therefore, in this study, extracted sugars of microalgae, which cause algal blooms and crude glycerol, a biodiesel industry byproduct, were used simultaneously to produce 2,3-BDO. The 2,3-BDO production using only extracted algal sugars was about 4.8 g/L at 18 h, and the production of 2,3-BDO using both extracted algal sugar and crude glycerol was about 7 g/L at 18 h. It was confirmed that the main culture with crude glycerol was increased 1.5-fold compared to the case of using only extracted algal sugars. In addition, four components of the main medium (ammonium sulfate, casein hydrolysate, yeast extract, and crude glycerol) were statistically optimized and the concentrations of the medium were 12, 16, 12, and 13 g/L, respectively. In addition, the final 2,3-BDO production was about 11g/L, which 1.6-fold higher than before the optimization process. As a result, it was confirmed that 2,3-BDO production is possible through the simultaneous use of algal sugars and crude glycerol, which can greatly contribute to the development of zero-waste processes.

Relieving unwanted strain Although the α-phase of formamidinium lead iodide (FAPbI 3 ) has a suitable bandgap for use in solar cells, it must be stabilized with additional cations. These compositions can adversely affect the bandgap and produce lattice strain that creates trap sites for charge carriers. Kim et al. found that substituting small, equimolar amounts of cesium and methylenediammonium cations for formamidinium reduced the lattice strain and trap densities. The enhancement in open-circuit voltage led to a certified power conversion efficiency of 24.4%, and encapsulated devices retained 90% of their initial efficiency after 400 hours of maximal power point operating conditions. Science , this issue p. 108

The purpose of this study is to compare the progression rate of bone union and clinical outcomes of opening wedge high tibial osteotomy (OWHTO) using allogenous bone chip or tri-calcium phosphate (TCP) granule as bone graft materials. The hypothesis was that the bone union progression in OWHTOs using TCP granule grafts would be comparable to that of OWHTOs using allogenous bone chip grafts. Between 2011 and 2013, 54 patients who had undergone OWHTO for genu varum and osteoarthritis were randomized to one of the two groups at five centres. TCP granule was used to fill the defect in 27 patients and lyophilized allogenous bone chip was used in the other 27 patients. The degree of bone union was classified on a five-point scale and evaluated using plain radiographs of the knee at 6 weeks, 3 months, 6 months, and 12 months postoperatively. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, pain Visual Analogue Scale (VAS) score and complications were also evaluated. The highest degree of bone union observed at 6 and 12 months postoperatively was grade 4, and the number of cases of union progression at each time-point was not significantly different between the two groups (p > 0.05). WOMAC and pain VAS scores also showed no differences between the two groups. No complications were observed during the 12-month period following OWHTO in either group. OWHTO using TCP granule bone substitute showed similar bone union rates and clinical outcomes compared to allogenous bone chip grafts. TCP granule can be used as bone substitutes instead of allogenous bone chip grafts in OWHTO. Level 1.

Biorefinery is drawing attention as an environmentally friendly technology due to increasing interest in sustainable development. Microalgal biomass is a promising feedstock for biorefinery because of its fast growth rate and low requirement for land. It is essential to treat the remained microalgal sludge (90 wt% of total microalgal biomass) after biorefinery to construct a true zero-waste microalgal biorefinery. However, few studies have reported methods of utilizing microalgal sludge, a by-product of biorefinery. In this study, the microalgal sludge was converted to biochar through pyrolysis. Physicochemical and electrochemical properties of microalgal sludge biochar (MASB) were then analyzed. A flexible all-solid-state microsupercapacitor was fabricated by manufacturing a composite with a conductive polymer. Element components of MASB presented the inherent presence of doping nitrogen compared to those of lignocellulosic biochar such as Miscanthus biochar (MB) and rice straw biochar (RB). The pyrolysis temperature of MASB was optimized to obtain a high degree of graphitization and 900 °C (range, 600 °C–1000 °C) was found to be an appropriate pyrolysis temperature. Nitrogen doping and graphitic structure of MASB-900 (MASB produced at 900 °C) affected the capacitive performance of the fabricated microsupercapacitor. The capacitance was 262.8 F g−1 at a current density of 0.1 A g−1 and the energy density was 36.5 Wh kg−1 at a power density of 224.4 W kg−1. These results were superior to those of other previously studied biochar-based supercapacitors. The proposed microsupercapacitor demonstrates the possibility of zero-waste biorefinery and a high value-added application of microalgal sludge.

The electrolytic reduction process in pyroprocessing of used fuel requires that fuel fragments be pre-treated to remove cesium and iodine. The effect of high temperatures and fuel fragment size on release of cesium was investigated over 10 h at a temperature of 1300–1400 °C for fuel fragments with an O/U ratio of 2.2. Re-fragmentation of the original fragments was observed as changes in cesium release count rates as fuel was heated from 484 to 1329 °C. The release of cesium is highly dependent on the size of fuel fragments and most of the cesium is released as the temperature is held at the maximum target value.

The presence of excess lead iodide in halide perovskites has been key for surpassing 20% photon-to-power conversion efficiency. To achieve even higher power conversion efficiencies, it is important to understand the role of remnant lead iodide in these perovskites. To that end, we explored the mechanism facilitating this effect by identifying the impact of excess lead iodide within the perovskite film on charge diffusion length, using electron-beam-induced current measurements, and on film formation properties, from grazing-incidence wide-angle X-ray scattering and high-resolution transmission electron microscopy. Based on our results, we propose that excess lead iodide in the perovskite precursors can reduce the halide vacancy concentration and lead to formation of azimuthal angle-oriented cubic α-perovskite crystals in-between 0° and 90°. We further identify a higher perovskite carrier concentration inside the nanostructured titanium dioxide layer than in the capping layer. These effects are consistent with enhanced lead iodide-rich perovskite solar cell performance and illustrate the role of lead iodide., Excess lead iodide in the mixed halide perovskites solar cells leads to high device performance but its origin remains elusive. Here Park et al. unveil the underlying microscopic mechanism to be promoting the oriented growth of the perovskites crystals and reducing the defect concentration.

Background Although two-stage exchange arthroplasty is considered a treatment of choice for chronic features of fungal PJI (periprosthetic joint infection), there is no consensus for local use of antifungal agent. The purpose of this study was to evaluate the efficacy of antifungal-impregnated cement spacer (AICS). Methods Nine patients who were diagnosed and treated for chronic fungal PJI after TKA in a single center from January 2001 to December 2016 were enrolled. Two-stage exchange arthroplasty was performed. During the 1st stage resection arthroplasty, AICS was inserted for all patients. Systemic antifungal medication was used during the interval between the two stage operations. Results The average duration from the initial symptom to fungal PJI diagnosis was 20 months (range, five to 72 months). Average erythrocyte sedimentation rate and C-reactive protein level at diagnosis were 56 mm/h (range, 30 to 89 mm/h) and 2.25 mg/dl (range, 0.11 to 3.97 mg/dl), respectively. Fungal PJI was confirmed by open debridement tissue culture in three cases (33%). The average number of operations before final exchange arthroplasty was 2.7 times (range, one to five times). Average duration of antifungal agent use confirmed by sensitivity test was seven months (range, four to 15 months). Mean interval between the two stage operations was six months (range, 1.5 to 15 months). After two-stage exchange arthroplasty, no patient had recurrent fungal infection during a mean follow-up of 66 months (range, 24 to 144 months). Conclusion Two-stage exchange arthroplasty with AICS is a very effective strategy with excellent outcomes. Level of evidence Case series, IV.

A retrospective review of prospectively collected radiographic and clinical data.This study aims to investigate the relationship between cage subsidence and bone mineral density (BMD), and to reveal the clinical implications of cage subsidence.Posterior lumbar interbody fusion (PLIF) has become one of the standard treatment modality for lumbar degenerative disease. However, cage subsidence might result in recurrent foraminal stenosis and deteriorate the clinical results. Furthermore, numbers of osteoporosis patients who underwent PLIF are increasing. Therefore, the information on the correlations between cage subsidence, BMD, and clinical results will be of great significance.A total 139 segments was included in this retrospective study. We examined functional rating index (Visual Analogue Scale for pain, Oswestry Disability Index, Short Form-36 score) preoperatively, and investigated their changes after postoperative 1 year. Correlation between cage subsidence and clinical scores was investigated. Plain anteroposterior and lateral radiograph were taken preoperatively and postoperatively and during follow-up. Preoperative BMD and subsidence measured by postoperative 1 year 3-dimensional computed tomography were achieved and their correlation was assessed.All postoperative clinical scores improved significantly compared with preoperative ones (pain Visual Analogue Scale: 7.34-2.89, Oswestry Disability Index: 25.34-15.86, Short Form-36: 26.45-16.46, all P0.001). BMD showed significant weak correlation with subsidence (r=-0.285, P0.001). Severe osteoporotic segments (T score-3.0) had more risk to develop severe subsidence (3 mm) compared with the segments in which T score were higher than -3.0 (P=0.012), and its odds ratio was 8.44. Subsidence had no significant correlation with all clinical scores.This study revealed that cage subsidence is relevant to BMD. However, it was demonstrated that subsidence is not related to the clinical deterioration. Therefore, PLIF procedure which is conducted carefully can be a good surgical option to treat lumbar degenerative disease for osteoporotic patients.

A nonlinear pressure controller to actively regulate the thrust of a solid propulsion system is presented. To compensate for the parametric uncertainties with respect to the chamber pressure induced by changing nozzle throat area, Lyapunov-based parameter adaptation method has been applied. In order to verify the effectiveness of the proposed control method, the experiments were carried out using the cold gas test equipment that can simulate the operating environment of variable thrust solid propulsion system. The experiment results show that the nonlinear pressure controller has better performance than conventional P and PI controller.

Background Bioactive glass-ceramics have the ability to directly bind to bones and have been widely used as bone graft substitutes due to their high osteoconductivity and biocompatibility. CaO-SiO2-P2O5-B2O3 glass-ceramics are known to have good osteoconductivity and are used as bone graft extenders. Methods This study aimed to evaluate the effects of the resorbing properties of glass-ceramics in bone fusion after producing and analyzing three types of CaO-SiO2-P2O5-B2O3 glass-ceramics with high osteoconductivity that had enhanced resorption by having an increased B2O3 content. The three types of CaO-SiO2-P2O5-B2O3 glass-ceramics with B2O3 contents of 8.0, 9.0, and 9.5 weight % were designated and grouped as P20B80, P10B90, and P5B95, respectively. Glass-ceramic types were tested for fusion rates and bone formation by employing the lumbar 5-6 intertransverse process fusion model in 51 New Zealand male rabbits. Bioactivity was assessed by soaking in simulated body fluid (SBF). Results In vitro study results showed sufficient hydroxycarbonate apatite layer formation occurred for P20B80 in1 day, for P10B90 in 3 days, and for P5B95 in 5 days after soaking in SBF. For the rabbit lumbar spine posterolateral fusion model, the autograft group recorded a 100% fusion rate with levels significantly higher than those of P20B80 (29.4%), P10B90 (0%), and P5B95 (14.3%), with high resorbing properties. Resorbing property differences among the three glass-ceramic groups were not significant. Histological results showed new bone formation confirming osteoconductivity in all three types of glass-ceramics. Radiomorphometric results also confirmed the resorbing properties of the three glass-ceramic types. Conclusions The high resorbing properties and osteoconductivity of porous glass-ceramics can be advantageous as no glass-ceramics remain in the body. However, their relatively fast rate of resorption in the body negatively affects their role as an osteoconductive scaffold as glass-ceramics are resorbed before bony fusion.

Background In cervical anterior approach, transverse skin incision is preferred due to cosmetic reasons. Precise skin incision is required to reach the surgery segment while minimizing soft tissue injury. Skin incision site is frequently identified using C-arm fluoroscopy or the carotid tubercle. Accordingly, this study was conducted to investigate the efficacy of skin incision using the carotid tubercle as a marker. Methods This study was retrospectively conducted on 114 patients who underwent anterior cervical surgery by the same surgeon from April 2004 to June 2012. The rate of the appropriate insertion of K-wire, which was inserted into the disc after anterior approach, into the surgery segment was compared between 62 patients where skin incision site was identified using C-arm fluoroscopy before skin incision and 52 patients where skin incision site was identified using carotid tubercle palpitation before surgery. Results The needle was shown to have been inserted into the planned site in 106 patients out of the total 114 patients. The appropriate insertion of the needle was shown in 59 patients of group I (95.2%) and in 47 patients of group II (90.4%). Although the success rate was higher in group I than group II, it was statistically insignificant. The success rate of one-segment surgery was shown to be 89.7% in group I and 82.6% in group II. Although the success rate was higher in group I than group II, it was statistically insignificant. The success rate of two-segment surgery was shown to be 100% in group I, and 96.4% in group II due to one case of the failure at C3-4 and C5-6. The success rate of three- and four-segment surgeries was shown to be 100% in both groups. Conclusions The identification of skin incision site via carotid tubercle palpation was useful for surgeries involving two or more segments. Furthermore, it could be useful for one-segment surgery if surgical site is identified using vertebral body or soft tissues such as longus collis rather than insertion into the disc.

†Background: Inflammation related hematological parameters vary greatly depending on patients. It is not well known how much increase of which parameter warrants suspicion of postoperative infection. This study proposes to identify the normal range and the predictive factors for postoperative infection by conducting a time series analysis of the hematological parameters of patients after the spinal posterior fusion. Methods: A retrospective study was done with 608 patients who underwent spinal posterior fusion with pedicle screw fixation. Laboratory assessment including the leucocyte, neutrophil, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) of patients for 2 weeks after operation. The patients were divided into the one-level fusion group (group I), the two-level fusion group (group II), the three or multi-level fusion or reoperation group (group III), and the postoperative infection group (group IV). Blood was drawn before breakfast prior to the operation, and then 2-3 days, 4-7 days, 8-11 days, and 12-14 days after the operation. The leucocyte count, neutrophil count, CRP, and ESR were measured. Results: From 4-7 days after the operation, the CRP and neutrophil count of group IV were significantly higher than those of group I and II, and from 8-11 days after operation, the CRP and neutrophil counts were significantly higher than those of all groups. Twelve to fourteen days after the operation, the neutrophil count of group IV was significantly higher than that of group I and II, while the neutrophil count of group III was also higher than that of group I. The lower limit of the 95% confidence interval (CI) of the CRP and neutrophil count group IV was greater than the upper limit of the 95% CI of group I and II. The ESR of group IV was significantly higher than that of group I and III. Conclusions: If the postoperative CRP and neutrophil counts are high, or if the CRP begins to rise again 8 days after the operation, the likelihood of infection increases, but caution must be exercised in interpreting the results. If the hematological parameters are higher than the lower limit of the 95% CI of the postoperative infection group, infection must be strongly suspected.

Metal halide perovskite solar cells (PSCs) have been considered to be one of the most promising next-generation energy harvesters over the past decades due to remarkably rapid improvement of power conversion efficiency in photovoltaics. However, energy harvesters based on the solar energy source have an intrinsic environment limitation for indoor applications. A feasible solution to the limitation is to add non-solar energy harvesting functions to the solar energy harvesters. Here, the piezoelectric properties of two types of metal halide PSCs are investigated, the 3D only and the 3D/2D structure, showing PCEs of 21.3% and 23.2%, respectively. Piezo-response force microscopy and synchrotron-based X-ray diffraction demonstrate that both types of PSC sample have piezoelectricity. Remarkably, the 3D/2D structure has considerably higher piezoelectric amplitude than the 3D-only. The deep level transient spectroscopy results reveal that the enhancement in the piezoelectricity of the 3D/2D structure originates from Pb-Br defects. This study unravels the role of defects in the piezoelectricity of metal halide PSCs and provides a direction to develop the multi-function energy harvesters based on the PSCs.