Strong Influence of Coadsorbate Interaction on CO Desorption Dynamics on Ru(0001) Probed by Ultrafast X-Ray Spectroscopy and Ab Initio Simulations.

We show that coadsorbed oxygen atoms have a dramatic influence on the CO desorption dynamics from Ru(0001). In contrast to the precursor-mediated desorption mechanism on Ru(0001), the presence of surface oxygen modifies the electronic structure of Ru atoms such that CO desorption occurs predominantly via the direct pathway. This phenomenon is directly observed in an ultrafast pump-probe experiment using a soft x-ray free-electron laser to monitor the dynamic evolution of the valence electronic structure of the surface species. This is supported with the potential of mean force along the CO desorption path obtained from density-functional theory calculations. Charge density distribution and frozen-orbital analysis suggest that the oxygen-induced reduction of the Pauli repulsion, and consequent increase of the dative interaction between the CO 5σ and the charged Ru atom, is the electronic origin of the distinct desorption dynamics. Ab initio molecular dynamics simulations of CO desorption from Ru(0001) and oxygen-coadsorbed Ru(0001) provide further insights into the surface bond-breaking process.

Eating behaviours in relation to emotional intelligence.

The purpose of the study was to examine the abnormal eating attitudes in judoists and the possible relationships between eating attitudes, emotional intelligence, and body dissatisfaction. A total of 20 national judoists and 25 control participants were enrolled in the study. Subjects completed the following questionnaires: The Eating Attitudes Test, The Body Image Assessment Scale-Body Dimensions and the Bar-On Emotional Intelligence Questionnaire. 30 % of the athletes (n=6) and 20% of the controls (n=5) presented disordered eating attitudes although these subjects were of normal weight. They also presented body dissatisfaction and had lower levels of emotional intelligence in comparison to the groups without disordered eating attitudes, particularly in factors such as intrapersonal (p<0.01), adaptability (p<0.05), stress tolerance (p<0.04) and general mood (p<0.04). The athletes reported using different weight loss methods such as self-induced vomiting (20%), fasting (40%), diuretics (15%), and laxatives (50%). Among disordered eating attitude groups (Controls+Judoists), Global EAT-26 was negatively correlated with stress tolerance (p<0.04: r=-0.64), emotional self-awareness (p<0.05: r=-0.70), general mood (p<0.01: r=-0.74), and positively correlated with body dissatisfaction (p<0.01: r=0.79). Results highlight the role of emotion in disordered eating attitudes, which is an important finding in terms of the prevention and management of disordered eating.

The work function of submonolayer cesium-covered gold: a photoelectron spectroscopy study.

Using visible and x-ray photoelectron spectroscopy, we measured the work function of a Au(111) surface at a well-defined submonolayer coverage of Cs. For a Cs coverage producing a photoemission maximum with a He-Ne laser, the work function is 1.61+/-0.08 eV, consistent with previous assumptions used to analyze vibrationally promoted electron emission. A discussion of possible Cs layer structures is also presented.

[Estimation of the glomerular filtration rate in elderly inpatients: comparison of four methods]. / Quelle méthode d'évaluation de la fonction rénale utiliser chez le sujet âgé hospitalisé en unité de court séjour gériatrique ? Comparaison de quatre méthodes.

PURPOSE: High variability has been observed in the estimation of the glomerular filtration rate (GFR) in older patients, according to the formula used and no single formula has been recommended to date. The aim of this study was to quantify the precision and accuracy of the GFR estimated by means of three formulas and the measurement of cystatin C. METHODS: This prospective study was conducted in an acute care geriatric unit. Participants were patients, aged 70 years and over, having a possible 24-hour urine collection. The GFR was estimated using the Cockroft-Gault (CG), the Modification of Diet in Renal Disease (MDRD), and the Creatinine Clearance (Cl-Cr) formulas. The serum level of cystatin C was also measured. RESULTS: Eighty-one patients were included in the study. CG formula underestimated the GFR by a mean difference of 8.65 ml/min, compared with MDRD formula. Cl-Cr underestimated the GFR by a mean difference of 7.56 ml/min, compared with CG formula, and by a mean difference of 16.79 ml/min, compared with the MDRD formula. The degree of discrepancy between CG and Cl-Cr estimates, and between Cl-Cr and MDRD estimates decreased as the estimated GFR approached normal values. MDRD best matched the measurement of cystatin C, followed by CG and Cl-Cr (Kappa coefficient=0.43, 0.22 and 0.16, respectively). CONCLUSION: Our study confirms the high variability of GFR in older patients and particularly in those with abnormal renal function, depending on the formula used. Serum cystatine C level and MDRD formula appear to be the most concordant estimates of GFR in this population.

Real-Time Elucidation of Catalytic Pathways in CO Hydrogenation on Ru.

The direct elucidation of the reaction pathways in heterogeneous catalysis has been challenging due to the short-lived nature of reaction intermediates. Here, we directly measured on ultrafast time scales the initial hydrogenation steps of adsorbed CO on a Ru catalyst surface, which is known as the bottleneck reaction in syngas and CO2 reforming processes. We initiated the hydrogenation of CO with an ultrafast laser temperature jump and probed transient changes in the electronic structure using real-time X-ray spectroscopy. In combination with theoretical simulations, we verified the formation of CHO during CO hydrogenation.

Effect of pedal rate on diurnal variations in cardiorespiratory variables.

Recently, it was observed that the freely chosen pedal rate of elite cyclists was significantly lower at 06:00 than at 18:00 h, and that ankle kinematics during cycling exhibits diurnal variation. The modification of the pedaling technique and pedal rate observed throughout the day could be brought about to limit the effect of diurnal variation on physiological variables. Imposing a pedal rate should limit the subject's possibility of adaptation and clarify the influence of time of day on physiological variables. The purpose of this study was to determine whether diurnal variation in cardiorespiratory variables depends on pedal rate. Ten male cyclists performed a submaximal 15 min exercise on a cycle ergometer (50% Wmax). Five test sessions were performed at 06:00, 10:00, 14:00, 18:00, and 22:00 h. The exercise bout was divided into three equivalent 5 min periods during which different pedal rates were imposed (70 rev x min(-1), 90 rev x min(-1) and 120 rev x min(-1)). No significant diurnal variation was observed in heart rate and oxygen consumption, whatever the pedal rate. A significant diurnal variation was observed in minute ventilation (p=0.01). In addition, the amplitude of the diurnal variation in minute ventilation depended on pedal rate: the higher the pedal rate, the greater the amplitude of its diurnal variation (p=0.03). The increase of minute ventilation throughout the day is mainly due to variation in breath frequency (p=0.01)--the diurnal variation of tidal volume (all pedal rate conditions taken together) being non-significant--but the effect of pedal rate x time of day interaction on minute ventilation specific to the higher pedal rate conditions (p=0.03) can only be explained by the increase of tidal volume throughout the day. Even though an influence of pedal rate on diurnal rhythms in overall physiological variables was not also evidenced, high pedal rate should have been imposed when diurnal variations of physiological variables in cycling were studied.

Surface chemistry. Probing the transition state region in catalytic CO oxidation on Ru.

Femtosecond x-ray laser pulses are used to probe the carbon monoxide (CO) oxidation reaction on ruthenium (Ru) initiated by an optical laser pulse. On a time scale of a few hundred femtoseconds, the optical laser pulse excites motions of CO and oxygen (O) on the surface, allowing the reactants to collide, and, with a transient close to a picosecond (ps), new electronic states appear in the O K-edge x-ray absorption spectrum. Density functional theory calculations indicate that these result from changes in the adsorption site and bond formation between CO and O with a distribution of OC-O bond lengths close to the transition state (TS). After 1 ps, 10% of the CO populate the TS region, which is consistent with predictions based on a quantum oscillator model.

Deoxycholic acid-induced apoptosis is switched to necrosis by bcl-2 and calphostin C.

We previously demonstrated that the cytotoxicity associated with exposure of HCT116 cells to deoxycholic acid was due to the induction of apoptosis. Here we show that this results in activation of caspase 3 and that over expression of bcl-2 can suppress this. Surprisingly, inhibition of apoptosis by over expression of bcl-2 or incubation with calphostin C, a PKC inhibitor, did not enhance cell survival, but instead caused a switchover to death by necrosis. Hence, DCA-induced apoptosis requires caspase activity and both bcl-2 and PKC can determine the type of cell death induced by deoxycholic acid.

Gavaserin and saltavalin, new peptide antibiotics produced by Bacillus polymyxa.

A strain of Bacillus polymyxa (BPl), isolated from cauliflower seeds, inhibited the growth of microbial phytopathogens. Growth of this strain in liquid medium containing lactose, ammonium sulfate, biotin, and amino acids, resulted in optimal inhibition in vitro. Two new antibacterial substances were isolated and purified from culture broth. Their molecular masses were, respectively, 911 and 903 daltons. The first compound was named gavaserin because it contained glutamic acid, alanine, valine, serine and 2,4-diaminobutyric acid, and octanoic acid. No fatty acid was detected in the second compound, which was named saltavalin because it contained serine, alanine, leucine, threonine, valine, and 2,4-diaminobutyric acid.

Optimization of glucosinolate separation by micellar electrokinetic capillary chromatography using a Doehlert's experimental design.

The aim of this study was to optimize by micellar electrokinetic chromatography the separation of four glucosinolates, i.e. sinigrin, glucobrassicin and methoxyglucobrassicin involved in Cruciferae resistance mechanisms and glucotropaeolin used as an internal standard. The separation borate buffer which contained sodium dodecyl sulphate, tetramethylammonium hydroxide and methanol was firstly optimized by using a three variable Doehlert experimental design. The optimum concentrations found enabled, for the first time, to obtain an acceptable resolution between the two indole glucosinolates, glucobrassicin and methoxyglucobrassicin. Modifications of the method such as a capillary pre-rinse with pure borate buffer and a step change in voltage during experiment were performed to improve the resolutions between glucosinolates and to reduce the analysis time. This method was validated by a statistical analysis and showed good linearity, repeatability and reproducibility.

Diurnal variations in cycling kinematics.

Physiological and biomechanical constraints as well as their fluctuations throughout the day must be considered when studying determinant factors in the preferred pedaling rate of elite cyclists. The aim of this study was to monitor the diurnal variation of spontaneous pedaling rate and movement kinematics over the crank cycle. Twelve male competitive cyclists performed a submaximal exercise on a cycle ergometer for 15 min at 50% of their W(max). Two test sessions were performed at 06:00 and 18:00 h on two separate days to assess diurnal variation in the study variables. For each test session, the exercise bout was divided into three equivalent 5-min periods during which subjects were requested to use different pedal rates (spontaneous cadence, 70 and 90 rev min(-1)). Pedal rate and kinematics data (instantaneous pedal velocity and angle of the ankle) were collected. The results show a higher spontaneous pedal rate in the late afternoon than in the early morning (p < 0.001). For a given pedal rate condition, there was a less variation in pedal velocity during a crank cycle in the morning than in the late afternoon. Moreover, diurnal variations were observed in ankle mobility across the crank cycle, the mean plantar flexion observed throughout the crank cycle being greater in the 18:00 h test session (p < 0.001). These results suggest that muscular activation patterns during a cyclical movement could be under the influence of circadian fluctuations.

Circadian rhythms during cycling exercise and finger-tapping task.

The aim of this study was to follow the circadian fluctuation of the spontaneous pedal rate and the motor spontaneous tempo (MST) in a sample of highly trained cyclists. Ten subjects performed five test sessions at various times of day. During each test session, subjects were required to perform (i) a finger-tapping task, in order to set the MST and (ii) a submaximal exercise on a cycle ergometer for 15 min at 50% of their Wmax. For this exercise, pedal rate was freely chosen. Spontaneous pedal rate and heart rate (HR) were measured continuously. The results demonstrated a circadian variation for mean oral temperature, HR, and MST. Under submaximal exercise conditions, HR showed no significant time-of-day influence although spontaneous pedal rate changed significantly throughout the day. Circadian rhythm of oral temperature and pedal rate were strongly correlated. Moreover, a significant positive correlation was found between MST and pedal rate. Both parameters may be controlled by a common brain oscillator. MST, rest HR, and pedal rate changes follow the rhythm of internal temperature, which is considered to be the major marker in chronobiology, therefore, if there is a relation between MST and pedal rate, we cannot rule out partial dependence of both parameters on body temperature.

Development of an immunoassay (ELISA) for the quantification of thiram in lettuce.

Two competitive immunoassays, a laboratory assay based on microwell plates and a field test based on the use of polystyrene tubes, have been developed for the quantification of thiram in lettuces. Concerning the laboratory assay, the calibration curve for thiram had a linear range of 11 to 90 ng/mL and a detection limit of 5 ng/mL. Precision of the assay presented coefficient of variation values <9% and the recovery of thiram from lettuce averaged 89% across the range of the immunoassay method using 30 min extraction with water/acetone (50:50, v/v). The tube-based method was developed in order that an extract of lettuce, containing thiram at the MRL (8 ppm), would be found on the linear part of the standard curve. The calibration curve for thiram has a linear range of 100 to 800 ng/mL (1.39 to 11.1 ppm in lettuce) and a detection limit of 40 ng/mL.

How to measure human adaptation in extreme environments: the case of Antarctic wintering-over.

BACKGROUND: Whether wintering-over causes cognitive and sensory impairment and associated adaptation problems is still a subject of debate. Conflicting results reported in the literature may be due to the difference in the experimental tasks. Moreover, interpersonal variability can hide the effects. HYPOTHESIS: Performance on cognitive and psychomotor tasks can be an indicator of adaptation problems. METHODS: Subjects were 10 scientists and 6 technicians (both clinically normal) who wintered-over for a year in the Antarctic. A subset of tasks of the AGARD battery of Standardized Tests for Research with Environmental Stressors (SB) was completed eight times during the isolation. To assess adaptation, the adaptability questionnaire (AQ) was completed by the physician before every performance test. RESULTS: SB showed a sensitive period of adaptation at mid-winter and at the end of the isolation, but the performance in the different tasks did not deteriorate exactly at the same time. No systematic relationship between AQ notations and SB performances was noted. However, three subjects showed significant positive correlations: r > 0.8, p < 0.05 (i.e., low adaptation = low performance). CONCLUSION: Some clinically normal individuals can experience adaptation problems, and SB tasks can be an indicator of these problems when comparisons are done at an individual level.

Real-time observation of surface bond breaking with an x-ray laser.

We used the Linac Coherent Light Source free-electron x-ray laser to probe the electronic structure of CO molecules as their chemisorption state on Ru(0001) changes upon exciting the substrate by using a femtosecond optical laser pulse. We observed electronic structure changes that are consistent with a weakening of the CO interaction with the substrate but without notable desorption. A large fraction of the molecules (30%) was trapped in a transient precursor state that would precede desorption. We calculated the free energy of the molecule as a function of the desorption reaction coordinate using density functional theory, including van der Waals interactions. Two distinct adsorption wells-chemisorbed and precursor state separated by an entropy barrier-explain the anomalously high prefactors often observed in desorption of molecules from metals.

Influence of temporal pressure on anticipatory postural control of medio-lateral stability during rapid leg flexion.

During leg flexion from erect posture, postural stability along the medio-lateral direction is organized in advance during "anticipatory postural adjustments" (APAs). This study aimed to investigate the influence of temporal pressure on this anticipatory postural control of medio-lateral stability. Eight young healthy participants performed series of leg flexions (1) as soon as possible in response to an acoustic signal (reaction-time condition; condition with temporal pressure) and (2) in a self-initiated condition (no temporal pressure). Results showed that APAs duration was shorter in the reaction-time condition as compared to the self-initiated condition; this shortening was compensated by an increase in the medio-lateral center-of-pressure displacement so that the dynamic stability reached at foot-off, as measured by the "extrapolated center-of-mass", remained unchanged. It is concluded that when a complex task is performed under temporal pressure, the central nervous system is able to modulate the spatio-temporal features of APAs in a way to both hasten the initiation of the voluntary movement and maintain optimal conditions of dynamic stability. In other words, it seems that the central nervous system does not "trade off optimal stability for speed of movement initiation under reaction-time condition", as it had been proposed in the literature.