Endoscopic transgastric fenestration versus percutaneous drainage for management of (peri)pancreatic fluid collections adjacent to gastric wall (with video).

BACKGROUND: Percutaneous drainage (PCD) and endoscopic approaches have largely replaced surgical drainage as the initial approach for (peri) pancreatic fluid collections (PFC)s, while complications associated with endoscopic stent implantation are common. AIM: To introduce a novel endoscopic therapy named endoscopic transgastric fenestration (ETGF), which involves resection of tissue by endoscopic accessory between gastric and PFCs without stent implantation, and to evaluate its efficacy and safety compared with PCD for the management of PFCs adjacent to the gastric wall. METHODS: Patients diagnosed with PFCs adjacent to the gastric wall and who subsequently received ETGF or PCD were restrospectively enrolled. Indications for intervention were consistent with related guidelines. We analyzed patients baseline characteristics, technical and clinical success rate, recurrence and reintervention rate, procedure-related complications and adverse events. RESULTS: Seventy-two eligible patients were retrospectively identified (ETGF = 34, PCD = 38) from October 2017 to May 2021. Patients in the ETGF group had a significantly higher clinical success rate than those in the PCD group (97.1 vs 76.3%, P = 0.01). There were no statistically significant differences regarding recurrence, reintervention and incidence of complication between the two groups. While long-term catheter drainage was very common in the PCD group. CONCLUSION: Compared with PCD, ETGF has a higher clinical success rate in the management of PFCs adjacent to the gastric wall. ETGF is an alternative effective strategy for the treatment of PFCs adjacent to the gastric wall.

Atorvastatin reduces contrast media-induced pyroptosis of renal tubular epithelial cells by inhibiting the TLR4/MyD88/NF-κB signaling pathway.

BACKGROUND: Contrast-induced acute kidney injury (CI-AKI) is the third most common cause of hospital-acquired renal failure. However, there is no effective treatment of CI-AKI, and its mechanism is unknown. Interestingly, atorvastatin has been reported to be effective in renal injury. Therefore, the aim of this study was to explore the effect and possible molecular mechanism of atorvastatin in CI-AKI. METHODS: On the CI-AKI in vitro model, rat tubular epithelial cells (NRK-52E) were treated with 18 mg I/ml meglumine diatrizoate (MEG) and then pretreated with atorvastatin. pcDNA3.1-TLR4 treatment was performed to overexpress toll-like receptor 4 (TLR4) in NRK-52E cells. Cell Counting Kit-8 (CCK-8) and lactate dehydrogenase (LDH) kits were used to detect NRK-52E cell viability as well as LDH release in each group, respectively; qRT-PCR to determine mRNA expression of TLR4 in cells; western blot to detect protein expression levels of pyroptosis-related proteins (NLRP3, caspase-1, ASC, and GSDMD) and TLR4/MyD88/NF-κB signaling pathway-related proteins (TLR4, MyD88, NF-κBp65, and p-NF-κB p65) in cells. RESULTS: MEG treatment significantly inhibited the viability of NRK-52E cells, increased pro-inflammatory factor levels and promoted pyroptosis, representing successful establishment of a rat tubular epithelial cell (NRK-52E) CI-AKI in vitro model. Notably, atorvastatin increased the activity of MEG-treated NRK-52E cells and alleviated cell injury in a concentration-dependent manner. In addition, atorvastatin significantly down-regulated the expression of TLR4 in MEG-treated NRK-52E cells. However, overexpression of TLR4 inhibited the effects of atorvastatin on increasing cell viability, alleviating cell injury, reducing pro-inflammatory factors (IL-1ß, IL-6, and TNF-α) levels, and inhibiting apoptosis (by down-regulating the expression of NLRP3, caspase-1, ASC, and GSDMD). Furthermore, atorvastatin also inhibited the expression of TLR4/MyD88/NF-κB pathway-related proteins (TLR4, MyD88, and p-NF-κB p65). CONCLUSION: Atorvastatin can attenuate CI-AKI through increasing the activity of MEG-treated renal tubular epithelial cells, relieving cell injury, as well as inhibiting pyroptosis and inflammation. More importantly, the mechanism was achieved by inhibiting the TLR4//MyD88/NF-κB signaling pathway.

Conjugated Poly(ionic liquid)-Based Nanoporous Membrane for Rapid Moisture Response.

Stimuli-responsive nanoporous materials represent a newly emerging category of functional materials, for which instant and significant response behavior is strongly demanded but still challenging. Herein, a new kind of conjugated poly(ionic liquid)s (PILs) synthesized via a simple one-pot spontaneous nucleophilic substitution and polymerization between 4,4'-vinylenedipyridine and propargyl bromide is reported. A nanoporous membrane actuator is further developed via ionic complexation between the current PIL and trimesic acid. The actuator carries a gradient density in the hydrophobicity content along the membrane cross-section, which results in a fast response to moisture.

Effects and safety of auricular acupressure on depression and anxiety in isolated COVID-19 patients: A single-blind randomized controlled trial.

Objective: Psychological distress such as depression and anxiety resulted from coronavirus disease 2019 (COVID-19) have attracted increasing attention. The aim of this randomized controlled trial is to evaluate the effects and safety of auricular acupressure on depression and anxiety in isolated COVID-19 patients. Methods: 68 participants diagnosed with COVID-19 pneumonia (18-80 years old, SDS ≥ 50, SAS ≥ 45) were recruited and randomly allocated to the auricular acupressure group and the sham auricular acupressure group by a computer-generated random number sequence from 9th June to 30th June 2022. The group allocation was only blinded to the participants. Those in the auricular acupressure group were attached magnetic beads against 4 auricular points Shenmen, Subcortex, Liver and Endocrine, while sham group used four irrelevant auricular points. Outcomes were measured by Zung Self-Rating Depression Scale (SDS) and Zung Self-Rating Depression Scale (SAS) before and after treatment in both groups through electronic questionnaire in mobile phones. Results: After treatment, statistically significant differences were found in scores of SAS in both groups (P < 0.001 in auricular acupressure group; P = 0.003 in sham group), and SDS scores reduced significantly in the auricular acupressure group (P = 0.002). Significant reduced SAS and SDS scores were achieved in the auricular acupressure group than that in the sham group (F = 4.008, P = 0.049, MD -7.70 95% CI: -9.00, -6.40, SMD -2.79 95% CI: -3.47, -2.11 in SDS; F = 10.186, P = 0.002, MD -14.00 95% CI: -15.47, -12.53, SMD -4.46 95% CI: -5.37, -3.56 in SAS). No adverse events were found in either group during the whole study. Conclusion: Auricular acupressure is an effective and safe treatment for alleviating symptoms of depressive and anxiety in patients with COVID-19. Clinical trial registration: https://www.chictr.org.cn//, identifier ChiCTR2200061351.

Tourism dependence and poverty alleviation thresholds in Chinese ethnic tourism.

Questions persist on the relationship between tourism dependence and economic growth in ethnic tourism areas. This study addresses such gaps by constructing a threshold regression model based on socio-economic data from 2006 to 2019 for nine sites in Enshi Prefecture of central China. ArcGIS and other open-source data were also used to visualize changing tourism resources in the region. Findings suggest that tourism dependence (the ratio of tourism-based GDP to overall GDP) significantly promotes economic growth in ethnic minority areas. However, the positive influence of tourism dependence on economic growth appears dynamic and non-linear - rising at first before falling when tourism dependence exceeded a threshold of 34%, with effects varying by site and year. Methods and findings make crucial theoretical contributions to understanding tourism dependence and poverty alleviation linkages. This paper also highlights the importance of political support and balanced investment in diverse industries to minimize decreasing returns beyond tourism dependence thresholds in destinations worldwide.

[Secondary metabolites of endophyte fungi Xylaria sp. from Coptis chinensis].

Two new polyketides, lasobutone A(1) and lasobutone B(2), along with three known compounds, guignardianone C(3), guignardic acid(4), and 4-hydroxy-17R-methylincisterol(5), were isolated from the endophytic fungi Xylaria sp. by silica gel, MCI, and preparative HPLC, which was separated from the Chinese medicinal material Coptis chinensis and cultivated through solid fermentation with rice. Their structures were elucidated on the basis of spectroscopic methods, such as MS, NMR, IR, UV, and ECD. Compounds 2 and 4 showed inhibitory activities against the nitric oxide(NO) production in the LPS-induced macrophage RAW264.7 with IC_(50) values of 58.7 and 42.5 µmol·L~(-1) respectively, while compound 5 exhibited cytotoxic activities against HT-29 with IC_(50) value of 14.3 µmol·L~(-1).

Extra Loading Dose of Dexmedetomidine Enhances Intestinal Function Recovery After Colorectal Resection: A Retrospective Cohort Study.

Importance: Postoperative gastrointestinal dysfunction (POGD) may be caused by postoperative vagus nerve tension inhibition and systemic inflammation. Dexmedetomidine (Dex) increases vagus nerve tone and affords an anti-inflammatory property, which may play a role in pathogenesis. Objective: To investigate whether a higher dose of Dex enhances gastrointestinal function recovery. Design: In this retrospective study, patients receiving colorectal surgery at the First Affiliated Hospital of Xi'an Jiaotong University from 2017 to 2019 were included. We evaluated the postoperative flatus time between recipients who received loading plus maintenance dose of DEX (LMD group, 237 recipients) and those who recieved maintenance dose of DEX (MD group, 302 recipients). Data were analyzed by logical regression and stratified and interaction analyses. The simulated pharmacokinetics of two DEX regimens was compared using the Tivatrainer software. Thirty paired blood samples from patients whose propensity scores matched with POGD-related factors at 24 h postoperatively were randomly selected, and their tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), d-lactate (DLA), acetylcholine (Ach), interleukin (IL)-10, lipopolysaccharide (LPS), IL-6, and inducible nitric oxide synthase (iNOS) levels were measured. Setting: Operating rooms and general surgery wards. Participants: Among the 644 patients undergoing colorectal surgery, 12 who had a colostomy, 26 without Dex infusion, 20 whose Dex administration mode cannot be classified, and 47 with a history of intestinal surgery were excluded. A total of 539 patients were included. Result: Compared with the MD group, the LMD group had a shorter recovery time to flatus; lower incidences of nausea, vomiting, abdominal distension, and abdominal pain (p < 0.05); and a slightly decreased heart rate. The LMD group was the independent factor of POGD (OR = 0.59, 95% CI = 0.41-0.87, p = 0.007) without being reversed in stratified and interaction analyses and had higher Dex plasma concentration from skin incision to 8 h postoperatively. The LMD group had a 39% and 43% increase in Ach and IL-10 levels, respectively, and a 33%-77% decrease in TNF-α, IL-6, COX-2, iNOS, LPS, and DLA levels (p < 0.05). Conclusion: Adding an extra loading dose of Dex can increase parasympathetic tone and decrease inflammation; hence, it can enhance postoperative gastrointestinal function recovery following colorectal surgery.

[A new polyketide of endophytic fungi Aspergillus sp. ZJ-58 from Coptis chinensis].

A new polyketide, coptaspin A(1), along with two known compounds 4-acetyl-3,4-dihydro-6,8-dihydroxy-3-methoxy-5-methylisocoumarin(2), and cytochalasin Z_(12)(3), was isolated from the endophytic fungi Aspergillus sp. ZJ-58, which was isolated from the genuine medicinal plant Coptis chinensis in Chongqing after solid-state fermentation on rice and silica gel, MCI, and HPLC-based separation. Their structures were elucidated by MS, NMR, IR, UV, and ECD. The newly isolated compound 1 showed moderate inhibitory activities against LPS-induced NO production in RAW264.7 macrophages with the IC_(50) value of 58.7 µmol·L~(-1), suggesting its potential anti-inflammatory activity.

14-Membered resorcylic acid lactone derivatives with their anti-inflammatory from the fungus Aspergillus sp. ZJ-65.

Two new 14-membered resorcylic acid lactone derivatives, ascarpins A (1) and B (2), together with three related known compounds (3-5) were isolated from the fungus Aspergillus sp. ZJ-65, obtaining from the intestine of grass carp. These structures were elucidated on the basis of extensive spectroscopic methods, chemical conversion, and comparison with literature. All isolates were tested for their inhibitory activity against LPS-induced NO production in RAW 264.7 macrophages. Among them, compounds 1-4 exhibited potential anti-inflammatory activity with IC50 values ranging from 7.6 to 48.3 µM.

Highly efficient detection of Cu2+ and B4 O7 2- based on a recyclable asymmetric salamo-based probe in aqueous medium.

An asymmetric salamo-based probe molecule (H2 L) was synthesized and characterized structurally. When DMF/H2 O (9:1) was used as the solvent, it was shown probe H2 L has high sensitivity to Cu2+ . Using high-resolution mass spectrometry and theoretical calculation, it was found that probe H2 L could form a more stable complex (1:1) with Cu2+ , the minimum limit of detection (LOD) of H2 L for Cu2+ was calculated as 9.95 × 10-8 M. In addition, probe H2 L could also be used to identify B4 O7 2- under the same detection conditions and the minimum LOD of H2 L for B4 O7 2- was calculated as 4.98 × 10-7 M. At the same time, density functional theory theoretical calculation further proved the flexibility of probe H2 L. Through the action of EDTA, probe H2 L had a cyclic ability to recognize Cu2+ , and showed a better response in the physiological pH range; probe H2 L had the characteristics of fast recognition speed and high efficiency. In addition, with probe H2 L test paper for Cu2+ and B4 O7 2- , the effect was more obvious. Meanwhile, probe H2 L can be used to quantitatively detect Cu2+ in water samples.

[Simulation of Water Quality Response of Guishui River Wetland Plants and Water Diversion].

A two-dimensional model MIKE21 coupled with a modified EcoLab module was applied to model the water quality of surface flow wetlands. In the model, vegetation effects, oxygen production, nutrient consumption by microorganisms and vegetation were set in the solutions of hydrodynamic, chemical, and biological processes. Based on the field investigation and measurements in the Guishui River wetland, the model was established for the downstream reaches of the Guishui River and the Sanli River. The model calculated the hydrodynamics and water quality changes by vegetation type and distribution. The model parameters were calibrated and results were validated using the measurements. The concentrations of ammonia nitrogen, phosphate, and total nitrogen at outflow decreased by 14.29%, 33.33%, and 20.00% in the presence of wetland vegetation compared to no wetland vegetation. During water circulation, the flow rate increased by 0.4 m3 ·s-1 at the inlet of Guishui and Sanli rivers, increasing the water level and velocity in some parts of the rivers. The water areas with vegetation in Sanli and Guishui rivers increased by 144.44% and 13.16%, respectively. The concentrations of ammonia nitrogen, phosphate, and total nitrogen at outflow decreased by 35.71%, 50.00%, and 46.67% compared to no wetlands and no circulation. The circulation strengthened the wetland purification function. The wetland vegetation distribution was organically integrated into the model for water quality calculation, which provides the technical support for the water quality response research under comprehensive measures such as river and lake wetland ecological restoration and water conservancy regulation.

Chemical Composition and Anti-Alzheimer's Disease-Related Activities of a Functional Oil from the Edible Seaweed Hizikia fusiforme.

Cholinergic disorder, oxidative stress, and neuroinflammation play important roles in the pathology of Alzheimer's disease. To explore the healthy potential of the edible seaweed Hizikia fusiforme on this aspect, a functional oil (HFFO) was extracted from this alga and investigated on its constituents by gas chromatography-mass spectrometry (GC/MS) in this study. Its anti-Alzheimer's related bioactivities including acetylcholinesterase (AChE) inhibition, antioxidation, and anti-neuroinflammation were evaluated, traced, and simulated by in vitro and in silico methods. GC/MS analysis indicated that HFFO mainly contained arachidonic acid (ARA), 11,14,17-eicosatrienoic acid (ETrA), palmitic acid, phytol, etc. HFFO showed moderate AChE inhibition and antioxidant activity. Bioactivity tracing using commercial standards verified that AChE inhibition of HFFO mainly originated from ARA and ETrA, whereas antioxidant activity mainly from ARA. Lineweaver-Burk plots showed that both ARA and ETrA are noncompetitive AChE inhibitors. A molecular docking study demonstrated low CDOCKER interaction energy of -26.33 kcal/mol for ARA and -43.70 kcal/mol for ETrA when interacting with AChE and multiple interactions in the ARA (or ETrA)-AChE complex. In the anti-neuroinflammatory evaluation, HFFO showed no toxicity toward BV-2 cells at 20 µg/mL and effectively inhibited the production of nitroxide and reduced the level of reactive oxygen species in lipopolysaccharide-induced BV-2 cells. The results indicated that HFFO could be used in functional foods for its anti-Alzheimer's disease-related activities.

A Zr-cluster based thermostable, self-healing and adaptive metallogel with chromogenic properties responds to multiple stimuli with reversible radical interaction.

A Zr-cluster based metallogel is synthesized via an unusual one-pot solvothermal method. The resulting metallogel is robust, adaptive, self-healing, highly thermostable and conductive. Moreover, the metallogel exhibits reversible stimuli-responsive properties. The gel could respond to at least four kinds of stimuli such as light, aliphatic amines, electricity and metals with color and fluorescence tunability. Importantly, the metallogel with electrochromic properties could be used as soft electrochromic devices for smart windows and electro display boards, and metalchromism provides a practical way for coating corrosion monitoring of metal materials.

[Design and exploration of genetic comprehensive experiments based on Ds insertion mutants].

The cultivation of innovative abilities has become an important guide for higher education in China. Strengthening the integrated knowledge to design experiments is an effective way to improve undergraduate students' innovative abilities. Herein we designed a comprehensive experiment for molecular genetics by utilizing a rice Ds insertion mutant identified previously in our research project. In the comprehensive experiment, we adopt the method of scientific research as the main line of teaching and take the interesting phenotype of the rice mutant as the breakthrough point to reform and innovate genetics laboratory teaching. On the basis of this, we combined the progressive teaching method and guided the students to learn the TAIL-PCR skill and conduct an innovative experiment through expanding their knowledge. The comprehensive experiment will deepen students' understandings of the relationship between genotypes and phenotypes, help them master the effective way of thinking and technologies for scientific research to further improve their ability of the integrated application capability of theory and practices.

Changes in DNA methylation during epigenetic-associated sex reversal under low temperature in Takifugu rubripes.

DNA methylation has frequently been implicated in sex determination and differentiation in teleost species. In order to detect the DNA methylation patterns established during sexual differentiation in tiger pufferfish T. rubripes, we performed comprehensive whole genome methylation sequencing and analyses of the gonads of male, female, and pseudo male. We obtained a total of 33.12, 32.44, and 31.60 Gb clean data for male, female, and pseudo male, with a sequencing depth of 66.44×, 60.47× and 54.86×, respectively. The methylation level of cytosine (C) residues in the genomic DNA from gonads was 11.016%, 10.428%, and 11.083% in male, female, and pseudo male, respectively. More than 65% of C methylation was at CpG sites, and less than 1% was at CHG and CHH sites. In each regulatory element, there were low methylation levels on both sides of the transcription start site, and higher methylation levels in exons, introns, and downstream of genes. The highest mCpG was on chromosome 8 and the lowest mCpG was on chromosome 5. Comparisons of whole-genome DNA methylation between pairs of samples revealed that there were 3,173 differentially methylated regions (DMRs) between female and male, and 3,037 DMRs between male and pseudo male, corresponding to 0.232% and 0.223% of the length of the genome, respectively. There were only 1,635 DMRs between female and pseudo male, representing 0.127% of the length of the genome. A number of differentially methylated genes (DMGs) related to sex determination and differentiation were selected, such as amhr2 and pfcyp19a. After Bisulfite Sequencing PCR (BSP) verification, amhr2 was exhibited low methylation level in normal males and pseudo male, and high methylation level in normal females but pfcyp19a showed low methylation level in normal females and high methylation level in normal males and pseudo males. These results provide information about the molecular epigenetic mechanisms of DNA methylation during low-temperature induced masculinization of tiger pufferfish, and increase our understanding of the mechanisms of sex determination and differentiation in this important aquaculture fish species.

Constructing Sensitive and Fast Lead-Free Single-Crystalline Perovskite Photodetectors.

We developed a high-performance photodetector based on (CH3NH3)3Sb2I9 (MA3Sb2I9) microsingle crystals (MSCs). The MA3Sb2I9 single crystals exhibit a low-trap state density of ∼1010 cm-3 and a long carrier diffusion length reaching 3.0 µm, suggesting its great potential for optoelectronic applications. However, the centimeter single crystal (CSC)-based photodetector exhibits low responsivity (10-6 A/W under 1 sun illumination) due to low charge-carrier collection efficiency. By constructing the MSC photodetector with efficient charge-carrier collection, the responsivity can be improved by three orders of magnitude (under 1 sun illumination) and reach 40 A/W with monochromatic light (460 nm). Furthermore, the MSC photodetectors exhibit fast response speed of <1 ms, resulting in a high gain of 108 and a gain-bandwidth product of 105 Hz. These numbers are comparable to the lead-perovskite single-crystal-based photodetectors.

The pore-forming protein Aep1 is an innate immune molecule that prevents zebrafish from bacterial infection.

Following the Aeromonas hydrophila aerolysin, various aerolysin-like pore-forming proteins have been identified from bacteria to vertebrates. We have recently reported the mechanism of receptor recognition and in vitro pore-formation of a zebrafish aerolysin-like protein Dln1/Aep1. However, the physiological function of Aep1 remains unknown. Here we detected that aep1 gene is constitutively expressed in various immune-related tissues of adult zebrafish; and moreover, its expression is significantly up-regulated upon bacterial challenge, indicating its involvement in antimicrobial infection. Pre-injection of recombinant Aep1 into the infected zebrafish greatly accelerated the clearance of bacteria, resulting in significantly increased survival rate. Meanwhile, the induced expression of cytokines such as interleukin IL-1ß and tumor necrosis factor TNF-α in zebrafish upon injection of recombinant Aep1 suggested that Aep1 may be a pro-inflammatory protein that triggers the antimicrobial immune responses. However, compared to the overproduction of these cytokines in the infected zebrafish, pre-injection of Aep1 could significantly reduce the expression level of these cytokines, accompanying with a reduced bacterial load. Moreover, the expression profiles through the developmental stages of zebrafish demonstrated that aep1 is activated at the very early stage prior to the maturation of adaptive immune system. Altogether, our findings proved that Aep1 is an innate immune molecule that prevents the bacterial infection.

Cardioprotective effects of rutin in rats exposed to pirarubicin toxicity.

We established both an acute and chronic cardiac toxicity rat model, which showed pretreatment with rutin attenuated pirarubicin-induced myocardial histopathological injury, electrocardiogram abnormalities, and cardiac dysfunction. Rutin also significantly reduced serum levels of MDA, BNP, CK-MB, CTnT, and LDH and increased serum SOD levels. Treatment with rutin and dexrazoxane resulted in an increase in Bcl-2/Bax ratio (p < 0.05) and reduction in JNK and Caspase-3 protein levels, compared to the pirarubicin group (all p < 0.05). Furthermore, rutin at a dose of 50 mg/kg significantly attenuated the above-mentioned alterations. Our study suggests the antioxidant and anti-apoptotic properties of rutin may be responsible for the cardioprotective effects observed.

The molecular and supramolecular aspects in mononuclear manganese(iii) Schiff-base spin crossover complexes.

Manganese(iii) hexadentate Schiff base complexes ([Mn(sal-N-1,5,8,12)]Y·S, Y = AsF6 (1); Y = SbF6 (2); Y = NO3, S = C2H5OH (3) and Y = Cl (4)) have been investigated to determine the impact of anion effects, intramolecular ligand distortions, and intermolecular supramolecular structures on the spin crossover (SCO) behavior. The crystal structure of [Mn(sal-N-1,5,8,12)]PF6, a complex known to exhibit an abrupt SCO behavior with an 8 K hysteresis window, reveals that this complex has a temperature-dependent anion order-disorder transition that disrupts the hydrogen-bonding chain upon SCO, indicating that hydrogen bonds between cations and anions greatly influence the magnetic properties. The SCO in 1 is mediated by intermolecular hydrogen-bonding interactions. The subtle balance of these hydrogen bonds induces a cooperative SCO process with a hysteresis width of 18 K, which is the largest one reported in the d4 SCO chemistry. For 2, crystal structural analysis indicates that changing the anion from AsF6- to SbF6- led to close stackings between phenyl groups from ligands. These stackings preclude the spin transition of the [Mn(sal-N-1,5,8,12)]+ cations. With NO3- and Cl- as counterions, the [Mn(sal-N-1,5,8,12)]+ cations are arranged more loosely and exhibit gradual SCO in the temperature range of 300-100 K. Careful evaluation of the supramolecular structures of these complexes and similar complexes reported previously revealed strong correlation between the supramolecular packing forces and their magnetic properties.

Niobium-Doped (001)-Dominated Anatase TiO2 Nanosheets as Photoelectrode for Efficient Dye-Sensitized Solar Cells.

TiO2 nanocrystals with different reactive facets have attracted extensive interest since they were first synthesized. The anatase TiO2 nanocrystals with (001) or (100) dominate facets were considered to be excellent electrode materials to enhance the cell performance of dye-sensitized solar cells. However, which reactive facet presents the best surface for benefiting photovoltaic effect is still unknown. We report a systematic study of various anatase TiO2 surfaces interacting with N719 dye by means of density functional theory calculations in combination with microscopic techniques. The (001) surface interacting with N719 would have the lowest work function, leading to the best photovoltaic performances. To further increase the efficiency, Nb dopant was incorporated into the anatase TiO2 nanocrystals. Based on the theoretical prediction, we proposed and demonstrated novel Nb-doped (001)-dominated anatase TiO2 nanosheets as photoelectrode in a dye-sensitized solar cell to further enhance the open-circuit voltage. And a power conversion efficiency of 10% was achieved, which was 22% higher than that of the undoped device (P25 as an electrode).