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The utilization of cocatalysts on the photoelectrode surface is a feasible strategy to achieve a high photocurrent density in the photoelectrochemical water oxidation process. The catalysts can enhance the activity by improving the reaction kinetics, retarding charge carrier recombination, or accumulating charge carriers. In this work, we have utilized a CuFe–CoFe Prussian blue (PB) catalyst layer on the BiVO4 photoanode surface to enhance its water oxidation activity. The hybrid catalyst, in which the semiprecious cobalt ions are partially substituted with earth-abundant copper ions, exhibits 56% higher photocurrent density than the CoFe PB-modified BiVO4. We show that photogenerated hole accumulation is present in the CuFe PB layer, which results in higher charge extraction from the BiVO4 surface. The CoFe PB layer on top of the CuFe one facilitates the charge transfer due to its catalytic activity toward the oxygen evolution reaction (OER).

Ketene, a versatile reagent in production of fine and specialty chemicals, is produced from acetic acid. We investigate the synthesis of ketene from acetic acid over the (3,0;1,1) surface of Cu2O(1 0 0) through analysis of the adsorption and desorption characteristics of formic and acetic acids. The results allow us to establish a reaction mechanism for ketene formation. Observations from x-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy, and temperature programmed desorption (TPD), supported by a comparison with formic acid results, suggest that acetic acid reacts with Cu2O through deprotonation to form acetate species coordinated to copper sites and hydroxylation of nearby surface oxygen sites. For formic acid the decomposition of adsorbed formate species results in desorption of CO2 and CO while, for acetic acid, high yields of ketene are observed at temperature >500 K. Modeling by density functional theory (DFT) confirms the strong interaction of acetic acid with the (3,0;1,1) surface and the spontaneous dissociation into adsorbed acetate and hydrogen atom species, the latter forming an OH-group. In an identified reaction intermediate ketene binds via all C and O atoms to Cu surface sites, in agreement with interpretations from XPS. In the vicinity of the adsorbate the surface experiences a local reorganization into a c(2 × 2) reconstruction. The total computed energy barrier for ketene formation is 1.81 eV in good agreement with the 1.74 eV obtained from TPD analysis. Our experimental observations and mechanistic DFT studies suggests that Cu2O can operate as an efficient catalyst for the green generation of ketene from acetic acid., Swedish Research Council (VR); VR Starting Grant; Knut och Alice Wallenbergs stiftelse; STINT Joint China-Sweden Mobility Program; Ragnar Holm Foundation; Trygger’s Foundation; Chalmers Areas of Advance-Materials Science

A one-step, facile and scalable hydrothermal route was employed to synthesize molybdenum disulfide (MoS2) nanoflowers (NFs) for use in the photodegradation of Congo red (CR) dye. The phase purity, ...

Hexavalent chromium, Cr(VI), is a toxic, mutagenic and carcinogenic species. We report here the semiconductor-based, photocatalytic reduction of Cr(VI) to trivalent chromium, Cr(III), using CdS nan...

Introduction: The aim of this retrospective study was to evaluate the long term success of using a ready to use metronidazole paste in the pulpal treatment of non-vital deciduous teeth. The assessment was performed by clinical and radiographic records obtained from follow-ups at 6-30 months. Materials and Methods: Data of 166 children, who had pulpal treatment on their deciduous teeth between April 2013 through June 2016 by a single pediatric dentist, were reviewed for the present study. A pre-treatment history of fistula or swelling, tenderness to percussion, presence of abscess, excessive tooth mobility, radiolucency in the bifurcation and/or periradicular and/or periapical area cases were eligible for inclusion. Finally a total of 42 children with 47 deciduous molars treated with metronidazole paste participated in the study. To determine the success at 6-30 months after treatment, the clinical/radiographic data were evaluated by the principal investigator and a co-investigator. Categorical data association was tested with Chi square test with significance levels at p Result: Success rate of non-vital deciduous teeth was determined as 83% at 6- 30 months after treatment and it was neither associated with gender (p=0.445), first/ second molar (p=0.692) nor maxillary/mandibular molar (p=0.853). Conclusion: Keeping a deciduous tooth in the arch is important to improve oral health of children. Metronidazole paste can be suggested to use for the local treatment of pulpal infections following a dental pulp necrosis and their complications in deciduous teeth, instead of performing extractions for them. Keywords: Dental caries, Deciduous molar, Lesion sterilization, Metronidazole paste, Pulpal treatment.

Developing active, durable, and inexpensive electrocatalysts is critical for hydrogen production to meet ever-growing sustainable energy needs. Nickel sulfides offer significant potential as electr...

International audience

BiVO4 is one of the most promising photoanode materials for water-splitting systems. Nitrogen incorporation into a BiVO4 surface overcomes the known bottleneck in its charge-transfer kinetics into the electrolyte. We explored the role of nitrogen in the surface charge recombination and charge-transfer kinetics by employing transient photocurrent spectroscopy at the time scale of surface recombination and water oxidation kinetics, transient absorption spectroscopy, and X-ray photoelectron spectroscopy. We attributed the activity enhancement mechanism to the accelerated V5+/V4+ redox process, in which incorporated nitrogen suppresses a limiting surface recombination channel by increasing the oxygen vacancies.

The morphology of the perovskite layer, the effective extraction of the charge carriers, and their transport are the main factors determining the power conversion efficiency (PCE) of the perovskite solar cells (PSCs). In this work, we demonstrated that the geometric and electronic structures of the PSCs could be modified by using a conductive polymer additive in the lead (Pb) halide layer prepared by a two-step deposition method. Polypyrrole (PPy) as a conductive polymer is used in the perovskite layers which could increase the PCE of CH3NH3PbI3-xClx mixed-halide PSCs. By adding an optimized amount of PPy, PCE has been raised from 10.4 to 13.2%. PPy acts as a conductive channel facilitating the extraction of the charge carriers and easing their transport in the perovskite layer. The crystallization is also affected by PPy which is advantageous to form smooth perovskite layers with fewer voids.

Background The Hall technique (HT) involves the placement of stainless steel crowns for treating asymptomatic carious primary teeth without tooth preparation or caries excavation. Aim To investigate whether temporomandibular dysfunction (TM-D) manifests in children after HT. Design Healthy children (age: 5-9 years) with dentin caries were treated with HT in a university clinic, and TM-D signs and symptoms were monitored in this cohort clinical trial. The primary outcome was TM-D signs recorded using the clinical dysfunction index (Di) at pre-treatment: 0-, 1-, 3-, 6-, and 12-month follow-up visits. The secondary outcome was TM-D symptoms recorded using a questionnaire. The Di and symptoms were compared over time using McNemar's tests. Results Thirty-nine children were followed for 12 months after HT treatment. Four children were detected as having dysfunction signs throughout the study: muscle pain on palpation and clicking. The symptoms 'hearing a sound within the jaw joint' or 'bite felt uncomfortable or unusual' were reported by another four children. The Di and TM-D symptoms were not significantly different between pre-treatment and follow-up visits (P > .05). Conclusions The HT does not seem to be connected to TM-D. Alternative TM-D assessment tools for studying non-persistent symptoms more comprehensively might be useful for future studies.

Focus of Presentation Australian studies examining muscle-strengthening activity (MSA) are limited and most are focused on resistance/weight training. This study uses the nationally representative Sport Australia AusPlay survey of physical activity participation and classifies activities that use major muscle groups as MSAs, adapting the methodology used in UK health studies. Using this classification, estimates are then made on how many Australian adults are doing MSAs on at least two days a week as per the Australian Physical Activity and Sedentary Behaviour Guidelines. Findings There is some uncertainty about which activities can be considered MSAs. However, evidence suggests that many activities, besides resistance/weight training, can strengthen muscles. Three definitions were used to classify physical activities reported by AusPlay respondents as either Resistance Training Only, Definitely MSAs, or Definitely and/or Potentially MSAs. These were applied to AusPlay 2017–18 data to estimate the proportion of adults who met the MSA guideline. For the primary measure of Definitely MSAs, estimates were higher than those from previous Australian studies. Consistent with previous Australian studies, a higher proportion of men than women, and younger adults than older adults, met the MSA guideline across all activity classifications. Conclusions/Implications Survey estimates of MSA participation depend on which activities are included as MSAs. More rigorous studies are needed to clearly categorise which activities can be considered as MSAs. Key messages A clearer understanding of what constitutes MSAs will improve estimates of how many Australian adults are meeting the MSA guidelines.

Postsynthetic treatments of BiVO4 photoanodes have recently shed light on better understanding and improving the photoanodes for water splitting. We demonstrate that a mild heat treatment of BiVO4 ...

The interaction of CO with Pt/3d/Pt(111) subsurface alloys (3d: Ni, Co, Fe) was investigated by combination of vibrational spectroscopy and temperature programmed desorption. The binding strength of CO is significantly reduced on Pt/Fe/Pt(111) and Pt/Co/Pt(111) and is sorted in the following order: Pt >Ni > Co approximate to Fe. Our analysis shows that the 3d admetal is stable in the subsurface region and CO is linearly bonded to the atop sites of the Pt(111) surface. At high CO coverage, compressed structures are obtained. At low CO coverage, the desorption activation energy of CO (similar to 143 kJ/mol for Pt(111)) drops to 124 kJ/mol for Pt/Ni/Pt(111), and goes further down to 111 and 110 kJ/mol for Pt/Co/Pt(111) and Pt/Fe/Pt(111), respectively. The enhancement in the surface activity is attributed to the modified backdonation to the antibonding states of adsorbed CO due to the downshifted 5d-band center of Pt upon embedding 3d metals in the subsurface region., Scientific and Technological Research Council of Turkey (TÜBİTAK); TARLA

The local structures of the water oxidation catalysts play an important role in reaction kinetics and the performance of the photoanodes. In this study, we deposited cobalt-based catalysts on nanoporous BiVO4 with controlled thicknesses by atomic layer deposition (ALD). Despite the similar oxidation states of cobalt in all depositions, different water oxidation activities in neutral pH conditions were observed. A dramatic photocurrent raise, lowered kinetic overpotential, and smaller charge transfer resistance across the photoanode/electrolyte interface were achieved when a uniform ultrathin Co(OH)(2) layer was formed on BiVO4. Photocurrent density for water oxidation showed a 95% enhancement at 0.6 V vs. RHE when the catalyst was in the form of Co(OH)(2), while an 80% increase was obtained for CoO. Ideal coordination of Co(OH)(2) on hydroxylated BiVO4 surface assists the charge transfer between the electrolyte and BiVO4 without increasing surface recombination. The results of this study emphasize the importance of controlling the local structure of the catalysts in the performance of the water splitting photoanodes. (c) 2020 Elsevier Ltd. All rights reserved.

Bibliometric profile of articles published by pediatric dentists from Turkey were investigated in this study. Records of articles written with a pediatric dentist author between 2000- 2019 indexed in TR-Index database were compiled. Recurrent records and articles without a pediatric dentist author were excluded. Abstracts and full texts of the articles were processed to gather data of; year published, language, articles area of interest (AoI), study design (Sd) and citation counts. Keyword co-occurrences were analyzed using VOSVIEWER® software.Spearman correlation analysis was performed between the numbers of dental schools, and number of published articles. Frequencies of categorical data were compared using chi square test. Differences between groups for continuous variables were assessed using Mann Whitney U test. P< 0.05 determined statistical significance. 512 articles were included. There was a positive correlation between the number of articles published and the number of dental schoolswho had started education(r=0.79, p< 0.001). The number of articles published in Turkish were more than English (X2= 157.531, 1) (p< 0.001). 300 of the articles were featured as research, 119 were reviews and 93 were case reports. Overall most frequently studied AoI was dental materials (23.8 %), followed by cariology/preventive dentistry (14.8%) and dental anomalies (10.2%). Laboratory research was the most preferred (26%) Sd, followed by literature review (23%), case reports (18.2%). Articles published in English were cited more than articles in Turkish (p= 0.02). Occurrences of the keywords were mostly nonspecific terms. Number of articles with pediatric dentist authors have been increasing remarkably since 2000. The increase in both the number of dental journals and the number of dental schools might have attributed to this trend. The next step for the authors of this field might be to branch out to less studied areas of interest and study designs to provide higher levels of evidence. [Med-Science 2020; 9(4.000): 901-6]

BiVO

A facial and large-scale compatible fabrication route is established, affording a high-performance heterogeneous plasmonic-based photoelectrode for water oxidation that incorporates a CoFe-Prussian blue analog (PBA) structure as the water oxidation catalytic center. For this purpose, an angled deposition of gold (Au) was used to selectively coat the tips of the bismuth vanadate (BiVO

A highly sensitive platform is demonstrated for hydrogen gas (H-2) sensing based on a polymer microcylinder ring resonator (PMRR) obtained by an optical fiber coated with an inner nanofilm of amorphous palladium (Pd) and an outer polymer layer of polydimethylsiloxane (PDMS) permeable to H-2. The sensing scheme is based on monitoring the spectral shifts of high-quality optical resonances called whispering gallery modes (WGMs) that propagate in the vicinity of the outer rim of the PDMS layer without being affected by the absorption and scattering losses caused by the Pd nanofilm. WGMs are excited by a single-mode tapered optical fiber evanescently coupled to the PMRR. The observed reversible spectral shifts of the WGMs are induced by changes in the diameter of the PDMS layer caused by expansion or contraction of the Pd nanofilm exposed to varying concentrations of H-2. Maximum spectral shift sensitivity of 140 pm/% H-2, a minimum response time of 95 s, and minimum limit of detection of similar to 60 ppm were measured for sensors prepared with different thicknesses of the amorphous Pd nanofilm and tested in the H-2 concentration range up to 1%, having nitrogen gas (N-2) as a carrier. Experiments were also conducted with Pd nanofilms annealed in air or N-2 atmosphere after the deposition. In both cases, smaller sensitivities were observed due to the formation of larger grains within the film, resulting in slower diffusion and reduced solubility of H in the Pd layer. The impacts of oxygen gas and humidity on sensor performance were also studied., Scientific and Technological Research Council of Turkey (TÜBİTAK)

The interfaces of graphene and hydrogenated graphene with 3d atom embedded Pt(111) [Pt-3d-Pt(111), 3d: Fe, Co] substrates have comparatively been investigated utilizing X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS), and temperature-programmed XPS (TPXPS) and desorption (TPD). 3d atoms in the subsurface layer of Pt(111) change the electronic properties of graphene via modifying its p-doping level. Hydrogenation makes graphene pinned to the Pt(111) and Pt-3d-Pt(111) substrates and induces surface segregation of 3d atoms from the subsurface layer into the interface of HGr and Pt-3d-Pt(111). Such a mechanism changes the desorption energetics of hydrogen significantly. (C) 2020 Elsevier Ltd. All rights reserved.

A facial and large-scale compatible fabrication route is established, affording a high-performance heterogeneous plasmonic-based photoelectrode for water oxidation that incorporates a CoFe-Prussian blue analog (PBA) structure as the water oxidation catalytic center. For this purpose, an angled deposition of gold (Au) was used to selectively coat the tips of the bismuth vanadate (BiVO4 ) nanostructures, yielding Au-capped BiVO4 (Au-BiVO4 ). The formation of multiple size/dimension Au capping islands provides strong light-matter interactions at nanoscale dimensions. These plasmonic particles not only enhance light absorption in the bulk BiVO4 (through the excitation of Fabry-Perot (FP) modes) but also contribute to photocurrent generation through the injection of sub-band-gap hot electrons. To substantiate the activity of the photoanodes, the interfacial electron dynamics are significantly improved by using a PBA water oxidation catalyst (WOC) resulting in an Au-BiVO4 /PBA assembly. At 1.23 V (vs. RHE), the photocurrent value for a bare BiVO4 photoanode was obtained as 190 μA cm-2 , whereas it was boosted to 295 μA cm-2 and 1800 μA cm-2 for Au-BiVO4 and Au-BiVO4 /PBA, respectively. Our results suggest that this simple and facial synthetic approach paves the way for plasmonic-based solar water splitting, in which a variety of common metals and semiconductors can be employed in conjunction with catalyst designs., Scientific and Technological Research Council of Turkey (TÜBİTAK); DPT-HAMIT; Turkish Academy of Sciences; TÜBA-GEBİP for Young İnvestigator Award; BAGEP for Young Scientist Award

We consider the application of a control variate technique for Deep Learning. In analogy to applications for Monte Carlo simulation or Fourier integration methods, this technique improves the quality of deep learning applied to option pricing problems. Many well known approximation methods are limited for practical applications but can be used as a control variate. For instance approximation formulas for SABR or the Black-Scholes price when pricing options in the Heston model. The neural network is only applied to calculate the difference to an accurate numerical method. In this way we increase the accuracy of applying neural nets since a large portion of the price is already mimicked by the control variate. This may result in a higher acceptance of such numerical techniques for financial applications.

Objective: This study aimed to investigate possible early childhood caries (ECC) risk indicators in preschoolers who applied for examination/treatment at the Government University Pediatric Dentistry Clinic, Istanbul, Turkey. Material and Methods: Children aged 36-71 months and their mothers who applied for examination/treatment and consented were enrolled in this cross-sectional survey during a 3-month period. Mother-child pairs were examined intraorally, and caries experience was recorded using (dmft/DMFT) an index. A structured questionnaire inquiring oral hygiene habits and diet history of the children was employed to interview the mothers. Categorical data from children with no clinical caries (NC), ECC, Severe ECC (S-ECC) were compared using Chi-square test and correlation of caries experience in mother-child pairs and were tested with Spearman rho. Statistical significance was set p

International audience; Single-atom catalysts have recently been subject to considerable attention within applied catalysis. However, complications in the preparation of well-defined single-atom model systems have hampered efforts to determine the reaction mechanisms underpinning the reported activity. By means of an atomic layer deposition method utilizing the steric hindrance of the ligands, isolated Fe1O3 motifs were grown on a single-crystal Cu2O(100) surface at densities up to 0.21 sites per surface unit cell. Ambient pressure X-ray photoelectron spectroscopy shows a strong metal–support interaction with Fe in a chemical state close to 3+. Results from scanning tunneling microscopy and density functional calculations demonstrate that isolated Fe1O3 is exclusively formed and occupies a single site per surface unit cell, coordinating to two oxygen atoms from the Cu2O lattice and another through abstraction from O2. The isolated Fe1O3 motif is active for CO oxidation at 473 K. The growth method holds promise for extension to other catalytic systems.

Single-atom catalysts have recently been subject to considerable attention within applied catalysis. However, complications in the preparation of well-defined single-atom model systems have hampered efforts to determine the reaction mechanisms underpinning the reported activity. By means of an atomic layer deposition method utilizing the steric hindrance of the ligands, isolated Fe

Electrodeposited and thermally oxidized copper surfaces have been documented in recent years to produce simple alcohols. In this work, we endeavored to study the electrochemical reduction of CO2 at different electrodes prepared via the electrodeposition method, namely, Cu–Cu2O, Cu–Cu2O–ZnO, and Cu–ZnO. In addition, thermally oxidized Cu (Cu-TO) was also investigated. C1, C2, and C3 species were produced on Cu–Cu2O–ZnO, Cu–Cu2O, and Cu–ZnO. The highest faradaic efficiency (FE of 97.4%) of the liquid products (methanol, formate, n-propanol, acetone) was evidenced on Cu–ZnO. The formation of C3 species with high FE on the Cu–ZnO electrode is attributed to the fast C–C–C coupling at the Cu–Zn interface. On thermally oxidized Cu, the total FE of the liquid products (methanol, formate, ethanol, acetate, n-propanol) was found to be 58.51%, which is considerably closer to the already reported values for these electrodes. Moreover, the Cu–Cu2O–ZnO electrode revealed selectivity toward methanol production. Detailed morphological and elemental analyses of the electrode, performed using XPS, Raman spectroscopy, and FESEM, as well as activity measurements to obtain an insight into the mechanistic pathways, reveal that C–C coupling is favored on Cu0 sites rather than Cu2O. Moreover, methanol formation seems to proceed via O coordination of CO2 to Cu–Cu2O surface having (100) facets, whereas C coordination is favored on Cu-TO with (111) exposed faces, resulting in Cu0 sites. The localized formation of ZnO nanoflowers was observed on Cu–ZnO electrodes after the electrochemical reduction of CO2, which is attributed to the mechanistic pathway involving chemical steps, leading to the formation of C3 species.