Boosting the Performance of WO3/n‐Si Heterostructures for Photoelectrochemical Water Splitting: from the Role of Si to Interface Engineering

Metal oxide/Si heterostructures make up an exciting design route to high‐performance electrodes for photoelectrochemical (PEC) water splitting. By monochromatic light sources, contributions of the individual layers in WO3/n‐Si heterostructures are untangled. It shows that band bending near the WO3/n‐Si interface is instrumental in charge separation and transport, and in generating a photovoltage that drives the PEC process. A thin metal layer inserted at the WO3/n‐Si interface helps in establishing the relation among the band bending depth, the photovoltage, and the PEC activity. This discovery breaks with the dominant Z‐scheme design idea, which focuses on increasing the conductivity of an interface layer to facilitate charge transport, but ignores the potential profile around the interface. Based on the analysis, a high‐work‐function metal is predicted to provide the best interface layer in WO3/n‐Si heterojunctions. Indeed, the fabricated WO3/Pt/n‐Si photoelectrodes exhibit a 2 times higher photocurrent density at 1.23 V versus reversible hydrogen electrode (RHE) and a 10 times enhancement at 1.6 V versus RHE compared to WO3/n‐Si. Here, it is essential that the native SiO2 layer at the interface between Si and the metal is kept in order to prevent Fermi level pinning in the Schottky contact between the Si and the metal.</p

Approximation of explicit model predictive control using regular piecewise affine functions: an input-to-state stability approach

Abstract Piecewise affine (PWA) feedback control laws defined on general polytopic partitions, as for instance obtained by explicit MPC, will often be prohibitively complex for fast systems. In this work we study the problem of approximating these high-complexity controllers by low-complexity PWA control laws defined on more regular partitions, facilitating faster on-line evaluation. The approach is based on the concept of input-to-state stability (ISS). In particular, the existence of an ISS Lyapunov function (LF) is exploited to obtain a priori conditions that guarantee asymptotic stability and constraint satisfaction of the approximate low-complexity controller. These conditions can be expressed as local semidefinite programs (SDPs) or linear programs (LPs), in case of 2-norm or 1, ∞-norm based ISS, respectively, and apply to PWA plants. In addition, as ISS is a prerequisite for our approximation method, we provide two tractable computational methods for deriving the necessary ISS inequalities from nominal stability. A numerical example is provided that illustrates the main results. The authors are with the Hybrid an

Presence of 1/f noise in the temporal structure of psychoacoustic parameters of natural and urban sounds.

1/f noise or pink noise, which has been shown to be universal in nature, has also been observed in the temporal envelope of music, speech, and environmental sound. Moreover, the slope of the spectral density of the temporal envelope of music has been shown to correlate well to its pleasing, dull, or chaotic character. In this paper, the temporal structure of a number of instantaneous psychoacoustic parameters of environmental sound is examined in order to investigate whether a 1/f temporal structure appears in various types of sound that are generally preferred by people in everyday life. The results show, to some extent, that different categories of environmental sounds have different temporal structure characteristics. Only a number of urban sounds considered and birdsong, generally, exhibit 1/f behavior on short to medium duration time scales, i.e., from 0.1 s to 10 s, in instantaneous loudness and sharpness, whereas a more chaotic variation is found in birdsong at longer time scales, i.e., of 10 s-200 s. The other sound categories considered exhibit random or monotonic variations in the different time scales. In general, this study shows that a 1/f temporal structure is not necessarily present in environmental sounds that are commonly perceived as pleasant

Role of pathogenic oral flora in postoperative pneumonia following brain surgery

<p>Abstract</p> <p>Background</p> <p>Post-operative pulmonary infection often appears to result from aspiration of pathogens colonizing the oral cavity. It was hypothesized that impaired periodontal status and pathogenic oral bacteria significantly contribute to development of aspiration pneumonia following neurosurgical operations. Further, the prophylactic effects of a single dose preoperative cefazolin on the oral bacteria were investigated.</p> <p>Methods</p> <p>A matched cohort of 18 patients without postoperative lung complications was compared to 5 patients who developed pneumonia within 48 hours after brain surgery. Patients waiting for elective operation of a single brain tumor underwent dental examination and saliva collection before surgery. Bacteria from saliva cultures were isolated and periodontal disease was scored according to type and severity. Patients received 15 mg/kg cefazolin intravenously at the beginning of surgery. Serum, saliva and bronchial secretion were collected promptly after the operation. The minimal inhibitory concentrations of cefazolin regarding the isolated bacteria were determined. The actual antibiotic concentrations in serum, saliva and bronchial secretion were measured by capillary electrophoresis upon completion of surgery. Bacteria were isolated again from the sputum of postoperative pneumonia patients.</p> <p>Results</p> <p>The number and severity of coexisting periodontal diseases were significantly greater in patients with postoperative pneumonia in comparison to the control group (p = 0.031 and p = 0.002, respectively). The relative risk of developing postoperative pneumonia in high periodontal score patients was 3.5 greater than in patients who had low periodontal score (p < 0.0001). Cefazolin concentration in saliva and bronchial secretion remained below detectable levels in every patient.</p> <p>Conclusion</p> <p>Presence of multiple periodontal diseases and pathogenic bacteria in the saliva are important predisposing factors of postoperative aspiration pneumonia in patients after brain surgery. The low penetration rate of cefazolin into the saliva indicates that its prophylactic administration may not be sufficient to prevent postoperative aspiration pneumonia. Our study suggests that dental examination may be warranted in order to identify patients at high risk of developing postoperative respiratory infections.</p

La criminalité féminine (une criminalité épicène et insolite)

La criminalité féminine est interrogée dans cette thèse sous l'angle de l'épistémologie clinique. La référence d'épistémologie clinique est ici celle de la théorie de la médiation initiée par Jean Gagnepain. Cette thèse envisage la criminalité féminine en mettant en perspective la biologie, la psychopathologie et la sociologie. En premier lieu est envisagé la spécificité du féminin dans la sexuation et la sexualité, puis dans le crime. La thèse est que les gemes féminin et masculin sont structuralement épicènes, et que la différence sexuelle biologique est réintroduite conjoncturalement dans le politique. Le politique dans la majorité des pays et des civilisations hormis l'ancienne Egypte et les pays scandinaves, ont toujours inscrits la femme en situation de minorât et d'insolite, voire de personne incomplète. La construction de savoir sur le féminin induit d'analyser les conditions anthropologiques de l'élaboration. Suit un recensement des modes de construction du féminin dans l'antiquité, à travers les mythes et la condition sociale de la femme. Cette perspective permet une comparaison de la détermination du féminin, ainsi que du masculin, et au-delà des modes mythiques et scientifiques de la détermination anthropologique. La deuxième partie propose une analyse située dans l'institutionnel prenant en charge la femme criminelle. Institutionnel que Jean Gagnepain nomme pouvoir modulaire, regroupant le didactique, le thérapeutique et le juridique. La troisième et dernière partie est consacrée aux illustrations cliniques des hypothèsesFemale criminality is questioned in this thesis under the angle of clinical epistemology. The clinical reference of epistemology is here that of the theory of the mediation initiated by Jean Gagnepain. This thesis considers female criminality by putting in prospect biology, psychopathology and sociology. Initially the specificity of female in the sexuation and sexuality is considered, then in the crime. The thesis is that the kinds female and male are structurally epicenes, and that the biological sexual difference is reintroduced conjoncturalement in the policy. The policy in the majority of the countries and civilizations except old Egypt and the Scandinavian countries, always registered the woman in situation of undervalued and strange, even of anybody incomplete. The construction of knowing about the female armature to analyze the anthropological conditions of the development. A census of the methods of construction of female in antiquity follows, through the myths and the social condition of the woman. This prospect allows a comparison of the determination of female, as weIl as masculine, and beyond the mythical and scientific modes of the anthropological determination. The second part proposes an analysis located in the institution al fascinating one charges the criminal woman of it. Institutional that Jean Gagnepain names modular capacity, gathering the didactic one, the therapeutic one and the legal one. The third and last part is devoted to the clinical illustrations of the assumptionsRENNES2-BU Centrale (352382101) / SudocSudocFranceF

Solution syntheses of unsupported Co(Ni)-Mo-S hydrotreating catalysts

Highly dispersed Ni(Co)-Mo-S sulfides were prepd. by simple room temp. soln. reactions using nickel or cobalt salts and thiomolybdate precursors in the presence of nonionic surfactants. The products were characterized by X-ray powder diffraction, sp. surface area measurements, and scanning and transmission electron microscopy. The evolution from amorphous pre-catalysts to highly dispersed sulfide catalysts during the activation step was studied by thermal anal. Extended X-ray absorption fine structure measurements were carried out to elucidate the chem. environment of the transition metals in the precursors and the sulfided catalysts. The specific catalytic activities of the Ni(Co)-Mo-S systems in the hydrodesulfurization of thiophene and 4,6-DMDBT were up to six times higher than those of com. alumina-supported systems