Perovskite precursor solution chemistry: from fundamentals to photovoltaic applications.

Over the last several years, inorganic-organic hybrid perovskites have shown dramatic achievements in photovoltaic performance and device stability. Despite the significant progress in photovoltaic application, an in-depth understanding of the fundamentals of precursor solution chemistry is still lacking. In this review, the fundamental background knowledge of nucleation and crystal growth processes in solution including the LaMer model and Ostwald ripening process is described. This review article also highlights the recent progress in precursor-coordinating molecule interaction in solution along with the role of anti-solvent in the solvent engineering process to control nucleation and crystal growth. Moreover, chemical pathways from precursor solution to perovskite film formation are given. This represents identification of the intermediate phase induced by precursor-coordinating molecule interaction and responsible intermediate species for uniform and dense perovskite film formation. Further to the description of chemical phenomena in solution, the contemporary progress in chemical precursor composition is also provided to comprehend the current research approaches to further enhance photovoltaic performance and device stability. On the basis of the critical and comprehensive review, we provide some perspectives to further achieve high-performance perovskite solar cells with long-term device stability through precisely controlled nucleation and crystal growth in precursor solution.

Phosphorylation and inactivation of glycogen synthase kinase 3ß (GSK3ß) by dual-specificity tyrosine phosphorylation-regulated kinase 1A (Dyrk1A).

Glycogen synthase kinase 3ß (GSK3ß) participates in many cellular processes, and its dysregulation has been implicated in a wide range of diseases such as obesity, type 2 diabetes, cancer, and Alzheimer disease. Inactivation of GSK3ß by phosphorylation at specific residues is a primary mechanism by which this constitutively active kinase is controlled. However, the regulatory mechanism of GSK3ß is not fully understood. Dual-specificity tyrosine phosphorylation-regulated kinase 1A (Dyrk1A) has multiple biological functions that occur as the result of phosphorylation of diverse proteins that are involved in metabolism, synaptic function, and neurodegeneration. Here we show that GSK3ß directly interacts with and is phosphorylated by Dyrk1A. Dyrk1A-mediated phosphorylation at the Thr(356) residue inhibits GSK3ß activity. Dyrk1A transgenic (TG) mice are lean and resistant to diet-induced obesity because of reduced fat mass, which shows an inverse correlation with the effect of GSK3ß on obesity. This result suggests a potential in vivo association between GSK3ß and Dyrk1A regarding the mechanism underlying obesity. The level of Thr(P)(356)-GSK3ß was higher in the white adipose tissue of Dyrk1A TG mice compared with control mice. GSK3ß activity was differentially regulated by phosphorylation at different sites in adipose tissue depending on the type of diet the mice were fed. Furthermore, overexpression of Dyrk1A suppressed the expression of adipogenic proteins, including peroxisome proliferator-activated receptor γ, in 3T3-L1 cells and in young Dyrk1A TG mice fed a chow diet. Taken together, these results reveal a novel regulatory mechanism for GSK3ß activity and indicate that overexpression of Dyrk1A may contribute to the obesity-resistant phenotype through phosphorylation and inactivation of GSK3ß.

Silencing of MUC8 by siRNA increases P2Y2-induced airway inflammation.

Mucin hypersecretion and overproduction are frequent manifestations of respiratory disease. Determining the physiological function of airway mucin is presently considered more important than identifying the relevant signaling pathways. The lack of a full-length human mucin 8 (MUC8) cDNA sequence has hindered the generation of a Muc8 knockout mouse line. Thus, the precise physiological functions of MUC8 are unclear. Herein, we investigated the function of MUC8 using a small-interfering RNA (siRNA)-mediated genetic silencing approach in human airway epithelial cells. Herein, intracellular IL-1α production was stimulated by an ATP/P2Y2 complex. While ATP/P2Y2 increased IL-1α secretion in a time-dependent manner, treatment with P2Y2-specific siRNA significantly decreased IL-1α secretion. Moreover, ATP increased P2Y2-mediated upregulation of MUC8 expression; however, IL-1α significantly decreased the extent to which ATP/P2Y2 upregulated MUC8 expression. Interestingly, treatment with MUC8-specific siRNA decreased the production of anti-inflammatory cytokines (TGF-ß and IL-1 receptor antagonist) and increased the production of inflammatory cytokines (IL-1α and IL-6) in our system. In addition, siRNA-mediated knockdown of MUC8 expression dramatically increased the secretion of inflammatory chemokines and resulted in an approximately threefold decrease in cell chemotaxis. We propose that MUC8 may function as an anti-inflammatory mucin that participates in inflammatory response by attracting immune cells/cytokines to the site of inflammation. Our results provide new insight into the physiological function of MUC8 and enhance our understanding of mucin overproduction during airway inflammation.

Minibrain/Dyrk1a regulates food intake through the Sir2-FOXO-sNPF/NPY pathway in Drosophila and mammals.

Feeding behavior is one of the most essential activities in animals, which is tightly regulated by neuroendocrine factors. Drosophila melanogaster short neuropeptide F (sNPF) and the mammalian functional homolog neuropeptide Y (NPY) regulate food intake. Understanding the molecular mechanism of sNPF and NPY signaling is critical to elucidate feeding regulation. Here, we found that minibrain (mnb) and the mammalian ortholog Dyrk1a, target genes of sNPF and NPY signaling, [corrected] regulate food intake in Drosophila melanogaster and mice. In Drosophila melanogaster neuronal cells and mouse hypothalamic cells, sNPF and NPY modulated the mnb and Dyrk1a expression through the PKA-CREB pathway. Increased Dyrk1a activated Sirt1 to regulate the deacetylation of FOXO, which potentiated FOXO-induced sNPF/NPY expression and in turn promoted food intake. Conversely, AKT-mediated insulin signaling suppressed FOXO-mediated sNPF/NPY expression, which resulted in decreasing food intake. Furthermore, human Dyrk1a transgenic mice exhibited decreased FOXO acetylation and increased NPY expression in the hypothalamus, and [corrected] increased food intake. Our findings demonstrate that Mnb/Dyrk1a regulates food intake through the evolutionary conserved Sir2-FOXO-sNPF/NPY pathway in Drosophila melanogaster and mammals.

Association between Preoperative C-Reactive Protein-to-Albumin Ratio and Mortality after Plastic and Reconstructive Surgery.

Background: Prognostic markers have not been extensively studied in plastic and reconstructive surgery. Objective: We aimed to evaluate the prognostic value of preoperative C-reactive protein (CRP)-to-albumin ratio (CAR) in plastic and reconstructive surgery and to compare it with the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and modified Glasgow prognostic score (mGPS). Methods: From January 2011 to July 2019, we identified 2519 consecutive adult patients who were undergoing plastic and reconstructive surgery with available preoperative CRP and albumin levels. The receiver operating characteristic (ROC) curve was generated to evaluate predictability and estimate the threshold. The patients were divided according to this threshold, and the risk was compared. The primary outcome was one-year mortality, and the overall mortality was also analyzed. Results: The one-year mortality was 4.9%. The CAR showed an area under the ROC curve of 0.803, which was higher than those of NLR, PLR, and mGPS. According to the estimated threshold of 1.05, the patients were divided into two groups; 1585 (62.9%) were placed in the low group, and 934 (37.1%) were placed in the high group. After inverse probability weighting, the mortality rate during the first year after plastic and reconstructive surgery was significantly increased in the high group (1.3% vs. 10.9%; hazard ratio, 2.88; 95% confidence interval, 2.17-3.83; p < 0.001). Conclusions: In this study, high CAR was significantly associated with one-year mortality of patients after plastic and reconstructive surgery. Further studies are needed on prognostic markers in plastic and reconstructive surgery.

Evaluation of ventricular pacing suppression algorithms in dual chamber pacemaker: Results of "LEADER" study.

Background: There is limited research on the intra-individual efficacy of ventricular pacing minimization algorithms developed by Biotronik-the Ventricular Pace Suppression algorithm (VpS) and the Intrinsic Rhythm Support plus algorithm (IRSplus) (BIOTRONIK SE & Co. KG, Berlin, Germany). We performed a randomized pilot trial that evaluated the efficacy of two algorithms in patients with symptomatic sinus node dysfunction (SND) who received a dual-chamber pacemaker. Methods: The trial was conducted in 11 tertiary hospitals in South Korea. The patients were randomized to either the VpS or IRSplus algorithm group after a 3-month period of fixed atrioventricular (AV) delay. The primary outcome was the ventricular pacing percentage (Vp%) at each follow-up visit. The secondary outcomes were the occurrence of heart failure (HF) and atrial fibrillation (AF) during the study period. Results: Data from 131 patients were analyzed. Initially, their average Vp% over 3 months with a fixed AV interval was 14.1 ± 19.4%. Patients were randomly assigned to VpS and IRSplus groups, with 66 and 65 in each. Algorithms reduced average Vp% to 4.0 ± 11.3% at 9 months and 6.7 ± 14.9% at 15 months. These algorithms were more effective for patients with paced AV delay (PAVD) ≤300 ms compared to those with PAVD >300 ms. Both algorithms were equally effective in reducing Vp%. Clinical AF or HF hospitalization was not observed during the study period. Conclusion: The VpS and IRSplus algorithms are effective and safe in minimizing unnecessary ventricular pacing in patients with SND.

Long-term clinical outcomes of image-guided percutaneous coronary intervention in acute myocardial infarction from the Korea Acute Myocardial Infarction Registry.

Imaging modalities for percutaneous coronary intervention (PCI), such as intravascular ultrasound (IVUS) or optical coherence tomography (OCT), have increased in the current PCI era. However, their clinical benefits in acute myocardial infarction (AMI) have not been fully elucidated. This study investigated the long-term outcomes of image-guided PCI in patients with AMI using data from the Korean Acute Myocardial Infarction Registry. A total of 9,271 patients with AMI, who underwent PCI with second-generation drug-eluting stents between November 2011 and December 2015, were retrospectively examined, and target lesion failure (TLF) at 3 years (defined as the composite of cardiac death, target vessel myocardial infarction, and ischemia-driven target lesion revascularization) was evaluated. From the registry, 2,134 patients (23.0%) underwent image-guided PCI (IVUS-guided: n = 1,919 [20.6%]; OCT-guided: n = 215 patients [2.3%]). Based on propensity score matching, image-guided PCI was associated with a significant reduction in TLF (hazard ratio: 0.76; 95% confidence interval: 0.59-0.98, p = 0.035). In addition, the TLF incidence in the OCT-guided PCI group was comparable to that in the IVUS-guided PCI group (5.3% vs 4.7%, p = 0.903). Image-guided PCI, including IVUS and OCT, is associated with favorable clinical outcomes in patients with AMI at 3 years post-intervention. Additionally, OCT-guided PCI is not inferior to IVUS-guided PCI in patients with AMI.

Regulation of RCAN1 protein activity by Dyrk1A protein-mediated phosphorylation.

Two genes on chromosome 21, namely dual specificity tyrosine phosphorylation-regulated kinase 1A (Dyrk1A) and regulator of calcineurin 1 (RCAN1), have been implicated in some of the phenotypic characteristics of Down syndrome, including the early onset of Alzheimer disease. Although a link between Dyrk1A and RCAN1 and the nuclear factor of activated T cells (NFAT) pathway has been reported, it remains unclear whether Dyrk1A directly interacts with RCAN1. In the present study, Dyrk1A is shown to directly interact with and phosphorylate RCAN1 at Ser(112) and Thr(192) residues. Dyrk1A-mediated phosphorylation of RCAN1 at Ser(112) primes the protein for the GSK3ß-mediated phosphorylation of Ser(108). Phosphorylation of RCAN1 at Thr(192) by Dyrk1A enhances the ability of RCAN1 to inhibit the phosphatase activity of calcineurin (Caln), leading to reduced NFAT transcriptional activity and enhanced Tau phosphorylation. These effects are mediated by the enhanced binding of RCAN1 to Caln and its extended half-life caused by Dyrk1A-mediated phosphorylation. Furthermore, an increased expression of phospho-Thr(192)-RCAN1 was observed in the brains of transgenic mice overexpressing the Dyrk1A protein. These results suggest a direct link between Dyrk1A and RCAN1 in the Caln-NFAT signaling and Tau hyperphosphorylation pathways, supporting the notion that the synergistic interaction between the chromosome 21 genes RCAN1 and Dyrk1A is associated with a variety of pathological features associated with DS.

Phosphorylation of Munc18-1 by Dyrk1A regulates its interaction with Syntaxin 1 and X11α.

Dual-specificity tyrosine(Y)-phosphorylation-regulated kinase 1A (Dyrk1A) is a protein kinase that might be responsible for mental retardation and early onset of Alzheimer's disease in Down's syndrome patients. Dyrk1A plays a role in many cellular pathways through phosphorylation of diverse substrate proteins; however, its role in synaptic vesicle exocytosis is poorly understood. Munc18-1, a central regulator of neurotransmitter release, interacts with Syntaxin 1 and X11α. Syntaxin 1 is a key soluble N-ethylmaleimide-sensitive factor attachment protein receptor protein involved in synaptic vesicle docking/fusion events, and X11α modulates amyloid precursor protein processing and ß amyloid generation. In this study, we demonstrate that Dyrk1A interacts with and phosphorylates Munc18-1 at the Thr(479) residue. The phosphorylation of Munc18-1 at Thr(479) by Dyrk1A stimulated binding of Munc18-1 to Syntaxin 1 and X11α. Furthermore, the levels of phospho-Thr(479) -Munc18-1 were enhanced in the brains of transgenic mice over-expressing Dyrk1A protein, providing in vivo evidence of Munc18-1 phosphorylation by Dyrk1A. These results reveal a link between Munc18-1 and Dyrk1A in synaptic vesicle trafficking and amyloid precursor protein processing, suggesting that up-regulated Dyrk1A in Down's syndrome and Alzheimer's disease brains may contribute to some pathological features, including synaptic dysfunction and cognitive defect through abnormal phosphorylation of Munc18-1.

Association between postoperative acute kidney injury and mortality after plastic and reconstructive surgery.

Acute kidney injury (AKI) is a common postoperative disorder that is associated with considerable morbidity and mortality. Although the role of AKI as an independent risk factor for mortality has been well characterized in major surgeries, its effect on postoperative outcomes in plastic and reconstructive surgery has not been evaluated. This study explored the association between postoperative AKI and mortality in patients undergoing plastic and reconstructive surgery. Consecutive adult patients who underwent plastic and reconstructive surgery without end-stage renal disease (n = 7059) at our institution from January 2011 to July 2019 were identified. The patients were divided into two groups according to occurrence of postoperative AKI: 7000 patients (99.2%) in the no AKI group and 59 patients (0.8%) in the AKI group. The primary outcome was mortality during the first year, and overall mortality and 30-days mortality were also compared. After inverse probability weighting, mortality during the first year after plastic and reconstructive surgery was significantly increased in the AKI group (1.9% vs. 18.6%; hazard ratio, 6.69; 95% confidence interval, 2.65-16.85; p < 0.001). In this study, overall and 30-day mortalities were shown to be higher in the AKI group, and further studies are needed on postoperative AKI in plastic and reconstructive surgery.

Dyrk1A phosphorylates p53 and inhibits proliferation of embryonic neuronal cells.

Down syndrome (DS) is associated with many neural defects, including reduced brain size and impaired neuronal proliferation, highly contributing to the mental retardation. Those typical characteristics of DS are closely associated with a specific gene group "Down syndrome critical region" (DSCR) on human chromosome 21. Here we investigated the molecular mechanisms underlying impaired neuronal proliferation in DS and, more specifically, a regulatory role for dual-specificity tyrosine-(Y) phosphorylation-regulated kinase 1A (Dyrk1A), a DSCR gene product, in embryonic neuronal cell proliferation. We found that Dyrk1A phosphorylates p53 at Ser-15 in vitro and in immortalized rat embryonic hippocampal progenitor H19-7 cells. In addition, Dyrk1A-induced p53 phosphorylation at Ser-15 led to a robust induction of p53 target genes (e.g. p21(CIP1)) and impaired G(1)/G(0)-S phase transition, resulting in attenuated proliferation of H19-7 cells and human embryonic stem cell-derived neural precursor cells. Moreover, the point mutation of p53-Ser-15 to alanine rescued the inhibitory effect of Dyrk1A on neuronal proliferation. Accordingly, brains from embryonic DYRK1A transgenic mice exhibited elevated levels of Dyrk1A, Ser-15 (mouse Ser-18)-phosphorylated p53, and p21(CIP1) as well as impaired neuronal proliferation. These findings suggest that up-regulation of Dyrk1A contributes to altered neuronal proliferation in DS through specific phosphorylation of p53 at Ser-15 and subsequent p21(CIP1) induction.

NiFeOx decorated Ge-hematite/perovskite for an efficient water splitting system.

To boost the photoelectrochemical water oxidation performance of hematite photoanodes, high temperature annealing has been widely applied to enhance crystallinity, to improve the interface between the hematite-substrate interface, and to introduce tin-dopants from the substrate. However, when using additional dopants, the interaction between the unintentional tin and intentional dopant is poorly understood. Here, using germanium, we investigate how tin diffusion affects overall photoelectrochemical performance in germanium:tin co-doped systems. After revealing that germanium is a better dopant than tin, we develop a facile germanium-doping method which suppresses tin diffusion from the fluorine doped tin oxide substrate, significantly improving hematite performance. The NiFeOx@Ge-PH photoanode shows a photocurrent density of 4.6 mA cm-2 at 1.23 VRHE with a low turn-on voltage. After combining with a perovskite solar cell, our tandem system achieves 4.8% solar-to-hydrogen conversion efficiency (3.9 mA cm-2 in NiFeOx@Ge-PH/perovskite solar water splitting system). Our work provides important insights on a promising diagnostic tool for future co-doping system design.

Dyrk1A-mediated phosphorylation of Presenilin 1: a functional link between Down syndrome and Alzheimer's disease.

The dual-specificity tyrosine(Y)-phosphorylation-regulated kinase 1A (Dyrk1A) gene is located on human chromosome 21 and encodes a proline-directed protein kinase that might be responsible for mental retardation and early onset of Alzheimer's disease (AD) in Down syndrome (DS) patients. Presenilin 1 (PS1) is a key component of the γ-secretase complex in the generation of ß-amyloid (Aß), an important trigger protein in the pathogenesis of AD. Increased Dyrk1A expression has been reported in human AD and DS brains. We previously showed that Dyrk1A increased Aß production in mammalian cells and transgenic mice that over-express Dyrk1A. In this study, we describe a potential mechanism by which Aß is increased in Dyrk1A-over-expressing DS and AD brains. First, we show that PS1 is phosphorylated by the Dyrk1A at Thr(354) and that this phosphorylation increases γ-secretase activity. Then, using transgenic mice that over-express human Dyrk1A, we demonstrate that phospho-Thr354-PS1 (pT354-PS1) expression is enhanced when Dyrk1A level is increased. We also show that pT354-PS1 is more stable than the unphosphorylated form of PS1. These results reveal a potential regulatory link between Dyrk1A and PS1 in the Aß pathway of DS and AD brains, suggesting that up-regulated Dyrk1A may accelerate AD pathogenesis through PS1 phosphorylation.

QSAR analysis of pyrazolidine-3,5-diones derivatives as Dyrk1A inhibitors.

Individuals with Down syndrome (DS) suffer from mental retardation. Overexpression and the resulting increased specific activity of Dyrk1A kinase located on chromosome 21 cause a learning and memory deficit in Dyrk1A transgenic mice. To search for therapeutic agents with Dyrk1A inhibition activity, previously we obtained HCD160 as a new hit compound for Dyrk1A inhibition. In the present study, we synthesized 34 HCD160 derivatives to investigate the quantitative structure-activity relationship (QSAR). This analysis could provide important information for novel drug discovery for treatment of DS related learning and memory deficits.

Thermal Stability of CuSCN Hole Conductor-Based Perovskite Solar Cells.

Although perovskite solar cells (PSCs) surpassing 20 % in certified power conversion efficiency (PCE) have been demonstrated with organic hole-transporting layers (HTLs), thermal degradation remains one of the key issues for practical applications. We fabricated PSCs using low temperature solution-processed CuSCN as the inorganic hole-transport layer (HTL), which possesses a highly stable crystalline structure and is robust even at high temperatures. The best-performing cell delivers a PCE of 18.0 %, with 15.9 % measured at the stabilized power output. Here we report the thermal stability of PSCs based on CuSCN in comparison with commonly used 2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (spiro-OMeTAD). The PSC fabricated with organic spiro-OMeTAD degrades to 25 % of initial PCE after annealing for 2 h at 125 °C in air under 40 % average relative humidity. However, CuSCN-based PSCs maintain approximately 60 % of the initial value, exhibiting superior thermal stability under identical conditions. This work demonstrates that high efficiency and improved thermal stability are simultaneously achieved when CuSCN is used as an HTL in PSCs.