Water electrolysis: from textbook knowledge to the latest scientific strategies and industrial developments.

Replacing fossil fuels with energy sources and carriers that are sustainable, environmentally benign, and affordable is amongst the most pressing challenges for future socio-economic development. To that goal, hydrogen is presumed to be the most promising energy carrier. Electrocatalytic water splitting, if driven by green electricity, would provide hydrogen with minimal CO2 footprint. The viability of water electrolysis still hinges on the availability of durable earth-abundant electrocatalyst materials and the overall process efficiency. This review spans from the fundamentals of electrocatalytically initiated water splitting to the very latest scientific findings from university and institutional research, also covering specifications and special features of the current industrial processes and those processes currently being tested in large-scale applications. Recently developed strategies are described for the optimisation and discovery of active and durable materials for electrodes that ever-increasingly harness first-principles calculations and machine learning. In addition, a technoeconomic analysis of water electrolysis is included that allows an assessment of the extent to which a large-scale implementation of water splitting can help to combat climate change. This review article is intended to cross-pollinate and strengthen efforts from fundamental understanding to technical implementation and to improve the 'junctions' between the field's physical chemists, materials scientists and engineers, as well as stimulate much-needed exchange among these groups on challenges encountered in the different domains.

Should we perform cervix removal during hysterectomy for benign uterine disease? Clinical practice guidelines from the French College of Gynecologists and Obstetricians (CNGOF).

OBJECTIVE: To provide guidelines from the French College of Obstetricians and Gynecologists (CNGOF), based on the best evidence available, concerning subtotal or total hysterectomy, for benign disease. METHODS: The CNGOF has decided to adopt the AGREE II and GRADE systems for grading scientific evidence. Each recommendation for practice was allocated a grade, which depends on the quality of evidence (QE) (clinical practice guidelines). RESULTS: Conservation of the uterine cervix is associated with an increased risk of cervical cancer (0.05 to 0.27%) and an increased risk of reoperation for cervical bleeding (QE: high). Uterine cervix removal is associated with a moderate (about 11 min) increase in operative time when hysterectomy is performed by the open abdominal route (laparotomy), but is not associated with longer operative time when the hysterectomy is performed by laparoscopy (QE: moderate). Removal of the uterine cervix is not associated with increased prevalence of short-term follow-up complications (blood transfusion, ureteral or bladder injury) (QE: low) or of long-term follow-up complications (pelvic organ prolapse, sexual disorders, urinary incontinence (QE: moderate). CONCLUSION: Removal of the uterine cervix is recommended for hysterectomy in women presenting with benign uterine disease (Recommendation: STRONG [GRADE 1-]; the level of evidence was considered to be sufficient and the risk-benefit balance was considered to be favorable).

Should we perform cervix removal during hysterectomy for benign uterine disease? Clinical practice guidelines from the French College of Gynecologists and Obstetricians (CNGOF)

To provide guidelines from the French College of Obstetricians and Gynecologists (CNGOF), based on the best evidence available, concerning subtotal or total hysterectomy, for benign disease. The CNGOF has decided to adopt the AGREE II and GRADE systems for grading scientific evidence. Each recommendation for practice was allocated a grade, which depends on the quality of evidence (QE) (clinical practice guidelines). Conservation of the uterine cervix is associated with an increased risk of cervical cancer (0.05 to 0.27%) and an increased risk of reoperation for cervical bleeding (QE: high). Uterine cervix removal is associated with a moderate (about 11 min) increase in operative time when hysterectomy is performed by the open abdominal route (laparotomy), but is not associated with longer operative time when the hysterectomy is performed by laparoscopy (QE: moderate). Removal of the uterine cervix is not associated with increased prevalence of short-term follow-up complications (blood transfusion, ureteral or bladder injury) (QE: low) or of long-term follow-up complications (pelvic organ prolapse, sexual disorders, urinary incontinence (QE: moderate). Removal of the uterine cervix is recommended for hysterectomy in women presenting with benign uterine disease (Recommendation: STRONG [GRADE 1-]; the level of evidence was considered to be sufficient and the risk-benefit balance was considered to be favorable).

Fe/Ni Bimetallic Organic Framework Deposited on TiO2 Nanotube Array for Enhancing Higher and Stable Photoelectrochemical Activity of Oxygen Evaluation Reaction.

Photoelectrochemical (PEC) water splitting is a promising strategy to improve the efficiency of oxygen evolution reactions (OERs). However, the efficient adsorption of visible light as well as long-term stability of light-harvesting electrocatalysis is the crucial issue in PEC cells. Metal-organic framework (MOF)-derived bimetallic electrocatalysis with its superior performance has wide application prospects in OER and PEC applications. Herein, we have fabricated a nickel and iron bimetallic organic framework (FeNi-MOF) deposited on top of anodized TiO2 nanotube arrays (TNTA) for PEC and OER applications. The FeNi-MOF/TNTA was incorporated through the electrochemical deposition of Ni2+ and Fe3+ onto the surface of TNTA and then connected with organic ligands by the hydrothermal transformation. Therefore, FeNi-MOF/TNTA demonstrates abundant photoelectrocatalytic active sites that can enhance the photocurrent up to 1.91 mA/cm2 under 100 mW/cm2 and a negligible loss in activity after 180 min of photoreaction. The FeNi-MOF-doped photoanode shows predominant photoelectrochemical performance due to the boosted excellent light-harvesting ability, rapid photoresponse, and stimulated interfacial energy of charge separation under the UV-visible light irradiation conditions. The results of this study give deep insight into MOF-derived bimetallic nanomaterial synthesis for photoelectrochemical OER and provide guidance on future electrocatalysis design.

Organocatalytic Multicomponent Synthesis of α/ß-Dipeptide Derivatives.

A straightforward multicomponent Knoevenagel-aza-Michael-cyclocondensation reaction involving readily available hydroxamic acid-derived from naturally occurring α-amino acids allows a diversity-oriented synthesis of novel isoxazolidin-5-ones possessing an N-protected α-amino acid pendant with good to high diastereoselectivities thanks to a match effect with a chiral organocatalyst. These diversely substituted heterocycles, easily isolated as a single diastereoisomer, proved to be versatile platforms for the formation of an array of α/ß-dipeptide fragments.

Oxidation of polyphenols and inhibition of photosystem II under acute photooxidative stress.

MAIN CONCLUSION: We observed a close correlation between the inhibition of photosystem II and the oxidation of polyphenols during an acute oxidative stress in sunflower leaf discs. To assess the physiological significance of polyphenols as antioxidants in planta, we compared the kinetics of polyphenols oxidation with the inhibition of the photosynthetic apparatus in sunflower leaf discs exposed to an acute photooxidative stress. Illumination of leaf discs in the presence of methyl viologen induced a rapid and large non-photochemical quenching of chlorophyll-a fluorescence, which was reversed after 4 h of treatment as indicated by the ≈ 30% increases of the steady-state (Fs) and maximal (Fm') levels of chlorophyll-a fluorescence relative to the first hour of treatment. This event coincided with the accelerated decreases of the maximum (Fv/Fm) and effective (∆F/Fm') quantum yields of photosystem II, and also with the beginning of polyphenols oxidation, estimated by the UV absorbance of methanolic leaf extracts, and supported by the Folin-Ciocalteu method and cyclic voltammetry. The decreases of Fv/Fm and the concentrations of reducing polyphenols were highly correlated (R2 = 0.877) during the experiment. Coherent with the decrease of UV absorbance of methanolic extracts, polyphenol oxidation resulted in a marked decrease of UV absorbance of leaf epidermis. Also, polymerization of oxidized polyphenols caused the accumulation of brown pigments in the MV-treated leaf discs, decreasing leaf reflectance, especially at 550 and 740 nm. Fluorescence intensities were also decreased during the MV treatment. Interestingly, the emission fluorescence ratio F740/F684 (excitation at 550 nm) decreased similarly to Fv/Fm (R2 = 0.981) due to the brown pigments. Moreover, the excitation fluorescence ratio F484/F680 (emission at 740 nm) was linearly correlated (R2 = 0.957) to ∆F/Fm', indicating a decrease of efficiency of energy transfer between the antenna pigments to the photosystem II reaction center during the oxidative stress. These results support the view that polyphenols can be effective antioxidants protecting the plants against reactive oxygen species.

Synthesis of calcium-deficient hydroxyapatite nanowires and nanotubes performed by template-assisted electrodeposition.

Hydroxyapatite (HA) has received much interest for being used as bone substitutes because of its similarity with bioapatites. In form of nanowires or nanotubes, HA would offer more advantages such as better biological and mechanical properties than conventional particles (spherical). To date, no study had allowed the isolated nanowires production with simultaneously well-controlled morphology and size, narrow size distribution and high aspect ratio (length on diameter ratio). So, it is impossible to determine exactly the real impact of particles' size and aspect ratio on healing responses of bone substitutes and characteristics of these ones; their biological and mechanical effects can never be reproducible. By the template-assisted pulsed electrodeposition method, we have for the first time succeeded to obtain such calcium-deficient hydroxyapatite (CDHA) particles in aqueous baths with hydrogen peroxide by both applying pulsed current density and pulsed potential in cathodic electrodeposition. After determining the best conditions for CDHA synthesis on gold substrate in thin films by X-ray diffraction (XRD) and Energy dispersive X-ray spectroscopy (EDX), we have transferred those conditions to the nanowires and nanotubes synthesis with high aspect ratio going until 71 and 25 respectively. Polycrystalline CDHA nanowires and nanotubes were characterized by Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). At the same time, this study enabled to understand the mechanism of nanopores filling in gold covered polycarbonate membrane: here a preferential nucleation on gold in membranes with 100 and 200 nm nanopores diameters forming nanowires whereas a preferential and randomly nucleation on nanopores walls in membranes with 400 nm nanopores diameter forming nanotubes.

Approach to the Mechanism of Hydrogen Evolution Electrocatalyzed by a Model Co Clathrochelate: A Theoretical Study by Density Functional Theory.

The hydrogen evolution reaction (HER) has attracted much attention within the scientific community because of increasing demands of modern society for clean and renewable energy sources. Molecular complexes of 3d-transition metals, such as cobalt, hold potential to replace platinum for the HER in acidic media. Among these, cage complexes such as tris-glyoximate metal clathrochelates, have demonstrated promising catalytic properties towards the HER. However, it is not clear whether the catalytic activity of this molecule stems from metal-centered activation of H+ , due to a low oxidation state of the metal stabilized by the surrounding organic cage, or if it is the organic cage playing a further cooperative role in bringing protons together. Herein, we report on a density functional theory study of two possible mechanisms for the HER catalyzed by a model Co clathrochelate. To assess the putative ligand involvement in the mechanism, several combinations of single and double protonation sites were investigated. The structural and energetic analysis of relevant intermediates suggests that the electrocatalytic mechanism is not based on the cooperation between the ligand and the metal. Instead, it is mainly due to the activation of H+ by the Co metallocenter. Our calculations further suggest that the last step in the mechanism is a proton coupled electron transfer step.

The use of FDI criteria in clinical trials on direct dental restorations: A scoping review.

OBJECTIVES: A scoping review was conducted to explore the use of FDI criteria 10 years after their introduction. The first aim was to compare the amount of studies using the FDI and/or the modified USPHS criteria. The second aim was to analyse the use of the FDI criteria in clinical trials evaluating direct dental restorations. DATA: Listing of studies using FDI and/or USPHS criteria per year since 2007. Clinical studies related to the assessment of direct restorations using FDI criteria. SOURCE: Two systematic searches - regarding the use of FDI and modified USPHS criteria - were carried out on Medline/Pubmed in order to identify the studies published between 2007 and 2017. Authors of the included articles were contacted to clarify their choice of FDI criteria in their studies. ClinicalTrials.gov database was also queried for the on-going studies that use FDI and modified USPHS criteria. STUDY SELECTION: In the first review, all the clinical trials (randomized/non-randomized, controlled, prospective/retrospective studies) that used FDI criteria to evaluate direct restorations on primary or permanent teeth were included. CONCLUSIONS: 16.3% of the studies used FDI criteria. The percentage of studies using them increased from 4.5% in 2010 to 50.0% in 2016. In average, 8.5 FDI criteria were used. The most employed criteria were: marginal adaptation (96.7%), staining (90.0%), fracture of material and retention (90.0%), recurrence of caries/erosion/abfraction (90.0%), post-operative sensitivity/tooth vitality (86.7%) and surface luster (60.0%). In addition, among the 27 on-going studies from ClinicalTrials.gov database, 51.9% use FDI criteria (including 87.5% with an open recruitment status). CLINICAL SIGNIFICANCE: FDI criteria were reported as practical (various and freely selectable), relevant (sensitive as well as appropriate to current restorative materials and clinical studies design), standardized (making comparisons between investigations easier). Investigators should go on using them for a better standardization of their clinical judgment, allowing comparisons with other studies.

One-step partial or complete caries removal and bonding with antibacterial or traditional self-etch adhesives: study protocol for a randomized controlled trial.

BACKGROUND: Current concepts in conservative dentistry advocate minimally invasive dentistry and pulp vitality preservation. Moreover, complete removal of carious dentin in deep carious lesions often leads to pulp exposure and root canal treatment, despite the absence of irreversible pulp inflammation. For years, partial caries removal has been performed on primary teeth, but little evidence supports its effectiveness for permanent teeth. Furthermore, the recent development of new antibacterial adhesive systems could be interesting in the treatment of such lesions. The objectives of this study are to compare the effectiveness of partial versus complete carious dentin removal in deep lesions (primary objective) and the use of an antibacterial versus a traditional two-step self-etch adhesive system (main secondary objective). METHODS/DESIGN: The DEep CAries Treatment (DECAT) study protocol is a multicenter, randomized, controlled superiority trial comparing partial versus complete caries removal followed by adhesive restoration. The minimum sample size required is 464 patients. Two successive randomizations will be performed (allocation ratio 1:1): the first for the type of excavation (partial versus complete) and the second (if no root canal treatment is required) for the type of adhesive (antibacterial versus traditional). For the two objectives, the outcome is the success of the treatment after 1 year, measured according to a composite outcome of five FDI criteria: material fracture and retention, marginal adaptation, radiographic examination (including apical pathologies), postoperative sensitivity and tooth vitality, and carious lesion recurrence. DISCUSSION: The study will investigate the interest of a conservative approach for the management of deep carious lesions in terms of dentin excavation and bioactive adhesive systems. The results may help practitioners achieve the most efficient restorative procedure to maintain pulp vitality and increase the restoration longevity. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT02286388 . Registered in November 2014.

Pneumatochemical impedance spectroscopy. 1. Principles.

Pneumatochemical impedance spectroscopy (PIS) is the indirect transposition of electrochemical impedance spectroscopy (EIS) to solid-gas reactions. In PIS analysis, an analogy is made between pressure and electrical potential on one hand and gas flow and electric current on the other hand, and pneumatochemical transfer functions are derived from gas-phase measurements. Potentially, this spectroscopy can be used to analyze the dynamics of any solid-gas system including adsorption (surface) and absorption (bulk) phenomena, gas (H2) permeation across metallic membranes, and electrocatalysis in gaseous fuel cells. Hydrogen absorption by intermetallic compounds (IMCs), a process of great practical interest for hydrogen storage applications, is more specifically considered in this paper, and the kinetic equations derived in this work pertain only to this case. Whereas classical electrochemical impedance measurements are performed using an harmonic analyzer and monochromatic potential (potentiostatic mode) or current (intentiostatic mode) perturbations, PIS investigation of the dynamics of IMC-H2(g) systems is more conveniently performed using Sievert's-type gas distribution apparatus (SGDA) and polychromatic pressure perturbation signals. This is first because monochromatic isothermal pressure modulations cannot be easily obtained experimentally over the frequency domain of interest and, second, because most IMC-H2(g) systems exhibit strongly nonlinear behaviors in two-phase domains (hysteresis), and this proscribes harmonic analysis. A further benefit of using SGDA and nonharmonic perturbations is that kinetic and thermodynamic information are collected simultaneously during the same experiment. The measurement and modeling of the pneumatochemical transfer functions associated with IMC-H2(g) systems, both in solid solution and two-phase domains, are discussed in this paper which is organized in two parts. The principles of PIS analysis, based on the theory of linear and time-invariant systems, are presented in the first part. The dynamics of hydrogen sorption by metals and IMCs is analyzed in the second part, where a detailed analysis of the multistep reaction paths involved in sorption mechanisms is proposed.

Pneumatochemical impedance spectroscopy. 2. Dynamics of hydrogen sorption by metals.

In this paper, pneumatochemical impedance spectroscopy is used to analyze multistep reaction mechanisms such as those observed in solid solution domains of LaNi5-H2(g) systems. It is shown that hydrogen sorption is a two-step mechanism including (i) dissociative surface chemisorption of molecular hydrogen and (ii) atomic hydrogen bulk transport by diffusion. Data fitting of experimental transfer functions with model equations yields the value of the kinetic parameter associated with each individual reaction step, i.e., surface sorption resistances and hydrogen bulk diffusion coefficients. The technique is used to follow the activation procedure of the sample as well as the degradation of sorption properties in oxygen-containing hydrogen atmospheres. A decrease in sorption kinetics is attributed to surface oxidation, whereas bulk properties remain unchanged. The perspectives offered by the technique which potentially can be used to optimize surface and bulk composition of IMC for increased sorption rates are discussed.

Residual stress in hydroxyapatite coating: nonlinear analysis and high-energy synchrotron measurements.

The thermal deposition of hydroxyapatite (HA) on titanium alloy substrate (Ti-6A1-4V) leads to a structure that has very good osseointegration properties. However, clinical failures have been occasionally reported at the interface between substrate and coating. Lifetime is the main parameter in such prostheses; therefore, in order to improve their quality, it is necessary to evaluate the level of stresses near the interface. The high-energy synchrotron radiation combines the advantages of a bulk analysis and reduced volume of the gauge. The objective of our study was to calculate the residual stress using a nonlinear finite-element model and to measure residual stress level near the interface, in the hydroxyapatite coating and in titanium alloy substrate with a nondestructive and high-resolution experiment. The high-energy synchrotron radiation of the BM16 beam-line at ESRF (Grenoble-France) was used with a resolution of down to 10 micrometers. The experimental measurements validate the results found by means of nonlinear finite-element analysis of the plasma spraying induced stress.