Enhanced Power Conversion Efficiency of Dye-Sensitized Solar Cells by Band Edge Shift of TiO2 Photoanode.

By simple soaking titanium dioxide (TiO2) films in an aqueous Na2S solution, we could prepare surface-modified photoanodes for application to dye-sensitized solar cells (DSSCs). An improvement in both the open-circuit voltage (Voc) and the fill factor (FF) was observed in the DSSC with the 5 min-soaked photoanode, compared with those of the control cell without any modification. The UV-visible absorbance spectra, UPS valence band spectra, and dark current measurements revealed that the Na2S modification led to the formation of anions on the TiO2 surface, and thereby shifted the conduction band edge of TiO2 in the negative (upward) direction, inducing an increase of 29 mV in the Voc. It was also found that the increased FF value in the surface-treated device was attributed to an elevation in the shunt resistance.

Influences of Sr-Incorporated TiO2 Layer on the Photovoltaic Properties of Dye-Sensitized Solar Cells.

Effects of a mixed overlayer composed of TiO2 and TiSrO3 on the performance of dye-sensitized solar cells (DSSCs) were investigated. The surface of TiO2 photoelectrode formed on F-doped SnO2 (FTO) was modified by soaking it in a TiCl4:SrCl2 mixed aqueous solution with various molar ratios and then calcining to produce the TiCl4:SrCl2-treated TiO2 photoelectrode (Ti:Sr-TiO2/FTO). The highest power conversion efficiency (PCE) was obtained from DSSC with Ti:Sr(7:3)-TiO2/FTO, which was prepared from the mixed solution with the molar ratio of 7:3 (TiOl4:SrCl2). An enhancement in short-circuit photocurrent (J(sc)) and open-circuit voltage (V(oc)) of DSSC with Ti:Sr(7:3)-TiO2/FTO was achieved, compared to those of the reference device with Ti:Sr(10:0)-TiC2/FTO (i.e., TiO2-coated TiO2/FTO). The incorporation of the mixed overlayer on the nanoporous TiO2 photoelectorde led to an improvement in the electron collection efficiency by a prolonged electron lifetime, thereby increasing the J(sc) value. The increase in V(oc) value of the device with Ti:Sr(7:3)-TiO2/FTO was due to the suppression of the charge recombination between injected electrons and I3(-) ions.

Sphingosine 1-phosphate receptor-1 enhances mitochondrial function and reduces cisplatin-induced tubule injury.

Sphingosine 1-phosphate (S1P), the natural sphingolipid ligand for a family of five G protein- coupled receptors (S1P1-S1P5Rs), regulates cell survival and lymphocyte circulation. We have shown that the pan-S1PR agonist, FTY720, attenuates kidney ischemia-reperfusion injury by directly activating S1P1 on proximal tubule (PT) cells, independent of the canonical lymphopenic effects of S1P1 activation on B and T cells. FTY720 also reduces cisplatin-induced AKI. Therefore, in this study, we used conditional PT-S1P1-null (PepckCreS1pr1(fl/fl)) and control (PepckCreS1pr1(w/wt)) mice to determine whether the protective effect of FTY720 in AKI is mediated by PT-S1P1. Cisplatin induced more renal injury in PT-S1P1-null mice than in controls. Although FTY720 produced lymphopenia in both control and PT-S1P1-null mice, it reduced injury only in control mice. Furthermore, the increase in proinflammatory cytokine (CXCL1, MCP-1, TNF-α, and IL-6) expression and infiltration of neutrophils and macrophages induced by cisplatin treatment was attenuated by FTY720 in control mice but not in PT-S1P1-null mice. Similarly, S1P1 deletion rendered cultured PT cells more susceptible to cisplatin-induced injury, whereas S1P1 overexpression protected PT cells from injury and preserved mitochondrial function. We conclude that S1P1 may have an important role in stabilizing mitochondrial function and that FTY720 administration represents a novel strategy in the prevention of cisplatin-induced AKI.

Ultrasound prevents renal ischemia-reperfusion injury by stimulating the splenic cholinergic anti-inflammatory pathway.

AKI affects both quality of life and health care costs and is an independent risk factor for mortality. At present, there are few effective treatment options for AKI. Here, we describe a nonpharmacologic, noninvasive, ultrasound-based method to prevent renal ischemia-reperfusion injury in mice, which is a model for human AKI. We exposed anesthetized mice to an ultrasound protocol 24 hours before renal ischemia. After 24 hours of reperfusion, ultrasound-treated mice exhibited preserved kidney morphology and function compared with sham-treated mice. Ultrasound exposure before renal ischemia reduced the accumulation of CD11b(+)Ly6G(high) neutrophils and CD11b(+)F4/80(high) myeloid cells in kidney tissue. Furthermore, splenectomy and adoptive transfer studies revealed that the spleen and CD4(+) T cells mediated the protective effects of ultrasound. Last, blockade or genetic deficiency of the α7 nicotinic acetylcholine receptor abrogated the protective effect of ultrasound, suggesting the involvement of the cholinergic anti-inflammatory pathway. Taken together, these results suggest that an ultrasound-based treatment could have therapeutic potential for the prevention of AKI, possibly by stimulating a splenic anti-inflammatory pathway.

Effect of anodic aluminum oxide template imprinting on TiO2 blocking layer of flexible dye-sensitized solar cell.

In this paper, we have proposed a new flexible dye-sensitized solar cell (DSSC) structure that employs an Anodic Aluminum Oxide (AAO) template imprinted TiO2 blocking layer, in which the AAO template creates TiO2 nano-particle aggregated islands on the TiO2 blocking layer. The TiO2 blocking layer prevents charge recombination between the metal foil and the liquid electrolyte. TiO2 nano-particle aggregated islands improve the scattering of incident light during back illumination and provide the wider surface area, yielding enhanced power conversion efficiency (PCE). All the flexible DSSC structure with TiO2 nano-particle aggregated islands on the TiO2 blocking layer exhibited higher photocurrent than did conventional DSSC because light that passed through the photoanode was scattered, thereby giving it improved PCE that was as much as 23% higher than that of a conventional DSSC. This proposed method is an effective manufacturing process for flexible DSSC.

Effects of Ga- and Al-codoped ZnO buffer layer on the performance of inverted polymer solar cells.

A Ga, Al-doped zinc oxide (GAZO) buffer layer was applied to inverted polymer solar cells (PSCs) based on P3HT [poly(3-hexylthiophene)]:PCBM [[6,6]-phenyl C61-butyric acid methyl ester] blend films. The work function of the GAZO layer on indium-tin oxide (ITO) was measured to be 4.45 eV. The insertion of the GAZO layer between the ITO electrode and the P3HT:PCBM blend film in the inverted PSC led to an improved short-circuit current (Jsc), open-circuit voltage (Voc) and fill factor (FF) compared to those of the reference cell without GAZO layer. The Jsc enhancement in the inverted PSC with the GAZO layer was attributed to both the effective electron extraction and the increased crystallinity of P3HT, and the work function difference between Ag and GAZO layer induced the increase in Voc. The improved FF value was due to the lowered series resistance and elevated shunt resistance. Thus, the power conversion efficiency of the device with the GAZO layer was improved by more than 200% relative to the reference cell.

Renal histology in patients with elevated serum creatinine and concurrent normal urinalysis.

INTRODUCTION: Diagnosis of kidney disease is currently and primarily based on the measurement of serum creatinine, blood urea nitrogen, and urine output, and most kidney diseases with elevated serum creatinine accompany abnormal findings of urinalysis with microscopy, such as proteinuria or hematuria. The purpose of the current study was to determine the histologic diagnosis of patients with elevated serum creatinine and a concurrent normal urinalysis without underlying disease. METHODS: The medical records of patients who had undergone kidney biopsies between January 1, 2003 and March 1, 2008 in three medical centers were retrospectively reviewed. The patients with an elevated serum creatinine level and a normal urinalysis were enrolled. The exclusion criteria were as follows: diabetes mellitus; hypertension; chronic liver disease; malignancies; autoimmune diseases; dependence on medications; hypokalemic nephropathy; age < 18 years. Age, duration of follow-up, post-biopsy management, and the change in levels of BUN and serum creatinine from pre-biopsy to the last visit were analyzed. RESULTS: All 15 patients were included. The most frequent single diagnosis was acute interstitial interstitial nephritis, followed by hypertensive nephrosclerosis. Chronic interstitial nephritis, mesangial proliferative glomerulonephritis, acute tubular necrosis, secondary amyoloidosis, focal segmental glomerulosclerosis, and minor glomerular change were listed. The young group (< 40 years of age) included more patients with acute interstitial nephritis, and the old group (≥ 40 years of age) included more patients with hypertensive nephrosclerosis. CONCLUSION: Based on a correct histological diagnosis, all of the patients, except one, were properly managed and had preserved kidney function until the last visit.

Inverted polymer solar cells with an ultrathin lithium fluoride buffer layer.

An ultrathin lithium fluoride (LiF) buffer layer was applied to inverted polymer solar cells with P3HT [poly(3-hexylthiophene)]:PCBM [[6,6]-phenyl C61-butyric acid methyl ester] blend films. By inserting the LiF layer between the transparent electrode and the P3HT:PCBM blend film, all parameters, including the short-circuit current, the open-circuit voltage and the fill factor, were enhanced compared to those of a reference cell without the LiF layer. The power conversion efficiency of the device with the LiF layer was thereby improved by more than 300% relative to the reference cell.

Substance P Improves Renal Ischemia Reperfusion Injury Through Modulating Immune Response.

Substance P (SP), an injury-inducible messenger that mobilizes bone marrow stem cells and modulates the immune response, has been suggested as a novel target for therapeutic agents. We evaluated the role of SP as an immune cell modulator during the progression of renal ischemic/reperfusion injury (IRI). Unilateral IRI induced the transient expression of endogenous SP and the infiltration of CCR7+ M1 macrophages in injured kidneys. However, SP altered the intrarenal macrophage polarization from CCR7+ M1 macrophages to CD206+ M2 macrophages in injured kidneys. SP also modulated bone marrow-derived neutrophils and mesenchymal stromal cells after IRI. SP treatment for 4 weeks starting one week after unilateral IRI significantly preserved kidney size and length and normal tubular structures and alleviated necrotic tubules, inflammation, apoptosis, and tubulointerstitial fibrosis. The beneficial effects of SP were accompanied by attenuation of intrarenal recruitment of CD4, CD8, and CD20 cells and abnormal angiogenesis. The immunomodulatory effect of SP suggested that SP could be a promising therapeutic target for preventing the progression of acute kidney injury to chronic kidney disease.

Erythropoietin attenuates renal injury in an experimental model of rat unilateral ureteral obstruction via anti-inflammatory and anti-apoptotic effects.

PURPOSE: Erythropoietin was recently shown to exert important cytoprotective and anti-apoptotic effects in injury models of the brain, heart and kidney. We examined whether erythropoietin also attenuates renal injury in a rat model of unilateral ureteral obstruction via anti-apoptotic and anti-inflammatory actions. MATERIALS AND METHODS: We divided Sprague-Dawley rats (Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea) into 4 groups, including 1-vehicle treated with sham operation, 2-vehicle treated with unilateral ureteral obstruction for 3 days, 3-erythropoietin treatment with sham operation and 4-erythropoietin treatment for unilateral ureteral obstruction for 3 days. The erythropoietin treatment dose was 3,000 IU/kg per day intraperitoneally, administered daily. We compared competitive reverse transcriptase-polymerase chain reaction data on transforming growth factor-beta, tumor necrosis factor-alpha, monocyte chemoattractant protein-1, osteopontin, Fas and Bcl-2. Furthermore, we examined Western blots for caspase-3 and light microscopy findings with hematoxylin and eosin staining. We applied immunohistochemistry for transforming growth factor-beta, ED-1 and caspase-3, and TUNEL in each group. RESULTS: Transforming growth factor-beta, tumor necrosis factor-alpha, monocyte chemoattractant protein-1, osteopontin and Fas mRNA levels in the erythropoietin treated, unilateral ureteral obstruction group were significantly lower than in the obstruction only group. The Bcl-2 mRNA level in the erythropoietin treated obstruction group was significantly higher than in the obstruction only group. Caspase-3 activity in the erythropoietin treated obstruction group was significantly lower than in the obstruction only group. On light microscopy interstitially infiltrated inflammatory cells were significantly decreased in the erythropoietin treated obstruction group compared to the obstruction only group. On immunohistochemistry the erythropoietin treated obstruction group showed significantly fewer reactions for transforming growth factor-beta, ED-1 and caspase-3 compared to the obstruction only group. Erythropoietin treatment in rats with unilateral ureteral obstruction significantly decreased the number of TUNEL positive cells. CONCLUSIONS: Erythropoietin exerts renoprotective effects in an experimental unilateral ureteral obstruction rat model via anti-apoptotic and anti-inflammatory actions.

Sildenafil attenuates renal injury in an experimental model of rat cisplatin-induced nephrotoxicity.

Sildenafil is the first commercially available selective inhibitor of phosphodiesterase-5 (PDE5) and is widely used for the treatment of erectile dysfunction. In recent years, investigations of the role of sildenafil in cardioprotection in animal models have received considerable interest. We evaluated whether sildenafil can attenuate cisplatin-induced nephrotoxicity in a rat experimental model. Male Sprague-Dawley rats were divided into five groups: control rats, sildenafil-control rats, cisplatin-injected rats (5 mg kg(-1) IP, single dose), sildenafil-treated cisplatin-injected rats (0.4 mg kg(-1), daily), and sildenafil+NG-nitro-l-arginine methyl ester hydrochloride (l-NAME)-treated rats. The molecular, functional, and structural parameters of the kidney were measured. At 96 h after cisplatin injection, serum levels of creatinine were lower in rats treated with both sildenafil+cisplatin compared with rats treated with cisplatin alone, and renal iNOS and eNOS expression was significantly higher in sildenafil+cisplatin-treated rats compared with rats treated with cisplatin alone (all P<0.05). Renal Bax gene and protein expression was significantly higher in cisplatin-treated rats compared with control rats, and sildenafil treatment significantly reduced the levels of Bax and increased the renal Bax/Bcl-2 ratio (P<0.05). Sildenafil treatment also reduced renal caspase-3 activation and TUNEL-positive apoptotic cells. These data suggest that sildenafil attenuates experimental cisplatin-induced nephrotoxicity by preventing apoptosis.

Effect of Combined Traditional Acupuncture, Pharmacopuncture and Applied Kinesiology on Lumbar Diseases of Resident Patients.

OBJECTIVES: Recently several Korean medical doctors have begun practicing applied kinesiology (AK). Although the efficacy of combining traditional acupuncture (TA) and pharmacopuncture (PP) on lumbar diseases such as lumbar spinal stenosis (LSS) and lumbar herniation of intervertebral disk (LHID) has been examined, the possible benefits of combining TA, PP and AK approaches have not been examined. Therefore the aim of this study was to develop effective treatment for lumbar disorders by combining TA, PP, and AK treatments. METHODS: Twenty-four patients hospitalized at Samse Korean Traditional Medicine Hospital between March and September 2018 with L5 or S1 root radiculopathy associated with LSS and LHID were included in this study. They were treated for 10 days with TA, PP and AK approaches that included category block, manipulation and strain/counterstrain treatments. The primary outcomes were mainly assessed using Japanese Orthopedic Association lumbar scores (JOALS). JOALS were determined before the start of treatment as well as five and 10 days after treatment started. RESULTS: The treatments improved the lumbar condition of the patients based on JOA pain score. CONCLUSION: The combined TA, PP and AK treatments were effective in treating spinal diseases of resident patients. Prospective, controlled, and relevant protocols using multimodal strategies to define the role of TA, PP and AK are needed.

Photovoltaic Performance of Dye-Sensitized Solar Cells Containing ZnO Microrods.

At an elevated temperature of 90 °C, a chemical bath deposition using an aqueous solution of Zn(NO3)2·6H2O and (CH2)6N4 resulted in the formation of both nanoflowers and microrods of ZnO on F-doped SnO2 glass with a seed layer. The nanoflowers and microrods were sensitized with dyes for application to the photoelectrodes of dye-sensitized solar cells (DSSCs). By extending the growth time of ZnO, the formation of nanoflowers was reduced and the formation of microrods favored. As the growth time was increased from 4 to 6 and then to 8 h, the open circuit voltage (Voc) values of the DSSCs were increased, whilst the short circuit current (Jsc) values varied only slightly. Changes in the dye-loading amount, dark current, and electrochemical impedance were monitored and they revealed that the increase in Voc was found to be due to a retardation of the charge recombination between photoinjected electrons and I3- ions and resulted from a reduction in the surface area of ZnO microrods. A reduced surface area decreased the dye contents adsorbed on the ZnO microrods, and thereby decreased the light harvesting efficiency (LHE). An increase in the electron collection efficiency attributed to the suppressed charge recombination counteracted the decreased LHE, resulting in comparable Jsc values regardless of the growth time.

Flexible Cu2ZnSn(S,Se)4 solar cells with over 10% efficiency and methods of enlarging the cell area.

For kesterite copper zinc tin sulfide/selenide (CZTSSe) solar cells to enter the market, in addition to efficiency improvements, the technological capability to produce flexible and large-area modules with homogeneous properties is necessary. Here, we report a greater than 10% efficiency for a cell area of approximately 0.5 cm2 and a greater than 8% efficiency for a cell area larger than 2 cm2 of certified flexible CZTSSe solar cells. By designing a thin and multi-layered precursor structure, the formation of defects and defect clusters, particularly tin-related donor defects, is controlled, and the open circuit voltage value is enhanced. Using statistical analysis, we verify that the cell-to-cell and within-cell uniformity characteristics are improved. This study reports the highest efficiency so far for flexible CZTSSe solar cells with small and large areas. These results also present methods for improving the efficiency and enlarging the cell area.

Fabrication of High Efficiency Dye-Sensitized Solar Cells Based on TiO2 Nanoparticles Embedded in Ti Substrate.

We have embedded a TiO2 nanoparticle (NP) photoelectrode in a Ti substrate to improve the cell efficiency of conventional TiO2 NP based dye-sensitized solar cells (DSSCs) using Ti substrate. Compared to the conventional standing-type (TiO2 NPs on Ti substrate) DSSCs, the embedded-type (TiO2 NPs embedded in Ti substrate) DSSCs have shown an approximately 35% improvement in power conversion efficiency due to the improvement of J(sc). The embedded-type DSSCs have more charge transport paths than do standing-type DSSCs due to the increase of contact area between the TiO2 NP sidewall and the Ti substrate. This increased contact area decreases the electrical resistance and increases the charge collection efficiency, which leads to the improvement of J(sc). The embedded-type NP-DSSCs are very effective DSSC structures for enhancing the power conversion efficiency of Ti substrate based DSSCs.

Effects of a Pretreatment on Al-Doped ZnO Thin Films Grown by Atomic Layer Deposition.

In this study, we investigated the electrical, structural, and optical properties of Al-doped ZnO (AZO) thin films approximately 50 nm thick grown by atomic layer deposition (ALD) on glass substrates at 200 °C. An H2O pretreatment was conducted for all AZO samples. The electrical properties of the AZO thin film were improved after the pretreatment process. The Al doping concentrations were controlled by inserting an Al2O3 cycle after every "n" ZnO cycles while varying n from 99 to 16. As the doping concentration increases, the resistivity decreases and the optical band gap increases. When the Al2O3 cycle ratio is 5%, the electrical resistivity showed the lowest value of 4.66 x 10(-3) Ω cm. A carrier concentration of 1.10 x 10(20) cm(-3), and the optical transmittance exceeding 90% were obtained in the visible and near-infrared region. The thin film was strongly textured along the (100) direction in the X-ray diffraction patterns.

Improved Photovoltaic Properties of Dye-Sensitized Solar Cells with KNO3-Modified Photoelectrodes.

The surface of a TiO2 photoelectrode was modified through a dip-coating process using an aqueous potassium nitrate (KNO3) solution to increase the power-conversion efficiency of dye-sensitized solar cells (DSSCs). The KNO3-modified TiO2 electrode was applied to the photoanode of the DSSCs. The DSSC with the KNO3-modified TiO2 electrode exhibited a short-circuit current (J(sc)) of 15.26 mA/cm2 and an open-circuit voltage (V(oc)) of 671 mV, compared with a J(sc) of 13.74 mA/cm2 and V(oc) of 654 mV for a reference device with a pristine TiO2 electrode. The results in combination with relevant data from electrochemical impedance spectroscopy, open-circuit voltage decay, and dark current measurements revealed that the modification of the TiO2 surface using the surface modifier (KNO3) led to a longer electron lifetime by the suppression of the charge recombination between injected electrons and I3- ions, resulting in an increase in both J(sc) and V(oc), compared with those of the reference device without surface modification.

Incorporation of Potassium Water Glass on Photoelectrodes and Its Effects on the Performance of Dye-Sensitized Solar Cells.

We applied potassium water glass (PWG) for a modification of photoelectrodes and investigated the effects of this modification on the photovoltaic properties of dye-sensitized solar cells (DSSCs). The PWG-modified TiO2 electrodes were prepared by soaking the TiO2 films in an aqueous PWG solution, and the resulting electrodes were applied to the photoanodes of DSSCs. Compared with a reference device with pristine TiO2 electrode, the power conversion efficiency of a DSSC with a PWG-modified TiO2 electrode was improved by about 26% because of the enhanced short-circuit photocurrent (J(sc)) and open-circuit voltage (V(oc)). Open-circuit voltage decay, electrochemical impedance spectroscopy, and dark current measurements revealed that the incorporation of PWG on the TiO2 surface led to a longer electron lifetime because of the suppression of charge recombination between injected electrons and I3(-) ions, which, compared with a reference device without surface modification, resulted in an increase in both J(sc) and V(oc).

Increased photovoltaic performance by the optimized TiClI4 and AlCl3 surface treatment in dye-sensitized solar cells.

The surface of TiO2 photoelectrodes coated on F-doped SnO2 (FTO) was modified by soaking it in a TiCl4:AlCl3 mixed aqueous solution with various molar ratios, and then calcining to produce the TiCl4:AlCl3-treated TiO2 photoelectrode (Ti:Al-TiO2/FTO). The highest power conversion efficiency (PCE) was obtained from dye-sensitized solar cells (DSSC) with Ti:Al(5:5)-TiO2/FTO, which was prepared from the mixed solution with the molar ratio of 5:5 (TiCi4:AlCl3). PCE of DSSC with Ti:Al (5:5)-TiO2/FTO was improved by ca. 19.6%, compared to that of the reference device with Ti:Al (10:0)-TiO2/FTO (i.e., TiO2-coated TiO2/FTO) due to an enhancement in both short-circuit photocurrent (J(sc)) and open-circuit voltage (V(oc)). A series of measurements such as UV-visible absorption, electrochemical impedance, open circuit voltage decay and dark current revealed that the increase in J(sc) was attributed to the improvement of electron collection efficiency by a prolonged electron lifetime, and the suppression of the charge recombination between injected electrons and I3(-) ions was found to increase the V(oc) value of the device with Ti:Al(5:5)-TiO2/FTO.

Highly reproducible planar Sb2S3-sensitized solar cells based on atomic layer deposition.

A high-quality Sb2S3 thin-absorber with controllable thickness was reproducibly formed by atomic layer deposition (ALD) technique. Compared with conventional chemical bath deposition (CBD), the Sb2S3 absorber deposited by ALD did not contain oxide or oxygen impurities and showed a very uniform thickness of Sb2S3 absorbers formed on a rough surface of dense blocking TiO2/F-doped SnOv (bl-TiO2/FTO) substrate. The planar ALD-Sb2S3 solar cells comprised of Au/Poly-3-hexylthiophene/ALD-Sb2S3/bl-TiO2/FTO showed significantly improved power conversion efficiency of 5.77% at 1 sun condition and narrow efficiency deviation, whereas the planar CBD-Sb2S3 solar cells exhibited 2.17% power conversion efficiency. The high efficiency and good reproducibility of ALD-Sb2S3 solar cell devices is attributed to reduced backward recombination because of the inhibition of oxide defects within ALD-Sb2S3 absorber and the conformal deposition of very uniform Sb2S3 absorbers on the blocking TiO2 surface by ALD process.