Thermal evolution of cobalt deposits on Co3O4(111): atomically dispersed cobalt, two-dimensional CoO islands, and metallic Co nanoparticles.

Cobalt oxide nanomaterials show high activity in several catalytic reactions thereby offering the potential to replace noble metals in some applications. We have developed a well-defined model system for partially reduced cobalt oxide materials aiming at a molecular level understanding of cobalt-oxide-based catalysis. Starting from a well-ordered Co3O4(111) film on Ir(100), we modified the surface by deposition of metallic cobalt. Growth, structure, and adsorption properties of the cobalt-modified surface were investigated by scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and infrared reflection absorption spectroscopy (IRAS) using CO as a probe molecule. The deposition of a submonolayer of cobalt at 300 K leads to the formation of atomically dispersed cobalt ions distorting the surface layer of the Co3O4 film. Upon annealing to 500 K the Co ions are incorporated into the surface layer forming ordered two-dimensional CoO islands on the Co3O4 grains. At 700 K, Co ions diffuse from the CoO islands into the bulk and the ordered Co3O4(111) surface is restored. Deposition of larger amounts of Co at 300 K leads to formation of metallic Co aggregates on the dispersed cobalt phase. The metallic particles sinter at 500 K and diffuse into the bulk at 700 K. Depending on the degree of bulk reduction, extended Co3O4 grains switch to the CoO(111) structure. All above structures show characteristic CO adsorption behavior and can therefore be identified by IR spectroscopy of adsorbed CO.

Point defects in the NiAl(100) surface.

The stability of various point defects in NiAl(100) has been investigated by first-principles calculations. For Al-rich surfaces, Ni vacancies within the first Al layer are energetically most favourable. For Ni-rich surfaces, so-called double defects, consisting of both Ni-antisite atom in the first Al layer and a Ni vacancy within the second Ni layer, form the configuration of lowest energy, superior to singular Ni antisites. An additional and significant energy gain is found in both cases by mutual lateral interaction of the defects, when they are arranged in the diagonal direction. Respective [Formula: see text] ordered configurations were found as the most stable structures. A 50:50 mixture of both defect types turns out to be even lower in energy than the ideal Al-terminated NiAl(100) surface, proving the latter to be metastable only. This is in line with the often reported inability in experiments to prepare ideal NiAl(100) surfaces.

Phases and phase transitions of hexagonal cobalt oxide films on Ir(100)-(1 × 1).

Cobalt oxides on the unreconstructed Ir(100) surface were prepared by reactive deposition of Co established by simultaneous oxygen flux at about 50 °C and subsequent annealing. The films were investigated by low-energy electron diffraction (LEED), scanning tunnelling microscopy (STM) and thermal desorption spectroscopy (TDS). We show that in spite of the quadratic unit mesh of the substrate, oxide films of (111) orientation develop. As long as oxygen-rich conditions are maintained they are of spinel-type Co(3)O(4)(111). They are non-pseudomorphic and transform to rocksalt-type CoO(111) when oxygen loss is induced by annealing at elevated temperatures. Thin films of CoO(111) are commensurate, and so, in order to realize that, they exhibit a slightly distorted unit cell when below a thickness equivalent to about seven cobalt monolayers. With increasing film thickness the uniaxial strain accompanied by the commensurability is gradually relieved by the insertion of dislocations so that eventually the film assumes ideal hexagonality. All CoO(111)-type surfaces are reconstructed at low sample temperatures equivalent to a [Formula: see text] superstructure. They reversibly transform into a (1 × 1) phase at about 50 °C.

Surface structure of polar Co(3)O(4)(111) films grown epitaxially on Ir(100)-(1 × 1).

Cobalt oxide films were prepared by oxidation of different amounts of cobalt deposited on Ir(100)-(1 × 1), where oxygen rich conditions were applied during deposition. The resulting oxide films with thicknesses of up to about 40 Å were investigated as regards their crystallographic structure and morphology, applying quantitative low energy electron diffraction (LEED) and scanning tunnelling microscopy (STM). It can be unequivocally shown that the spinel-type Co(3)O(4) phase develops, for which an excellent fit between measured and calculated LEED intensity spectra is achieved (Pendry R-factor R = 0.124). In spite of the quadratic unit cell of the substrate the oxide films are in the polar (111) orientation. Also, the native lattice parameter of the material is assumed, i.e. there is no pseudomorphic relation to the substrate. However, by means of orientational epitaxy, one of the unit-mesh vectors of the oxide and one of those of the substrate layer are aligned, leading to two mutually orthogonal domains in the oxide. The oxide is terminated by a sublayer of cobalt ions which in the bulk were tetrahedrally coordinated Co(2+) ions. There are drastic relaxations of layer spacings at and near the surface. As a consequence, the bond length between the surface terminating cobalt ions and oxygen ions below is considerably reduced, indicative of a substantial change of the ionicity of the cobalt and/or oxygen ions. This is interpreted as accounting for polarity compensation of the film, as surface reconstruction, oxygen vacancies and species adsorbed can be ruled out.

[Does red blood cell storage time still influence ICU survival?]. / L'âge des culots globulaires transfusés influence-t-il toujours le pronostic des patients en réanimation ?

OBJECTIVE: Few studies have shown that aged packed red blood cells (RBC) transfusion negatively influenced the outcome of ICU patients, probably related to storage lesions which could be decreased by leukodepletion of RBC. The purpose of this study was to evaluate the impact of aged leukodepleted-RBC pack, on the outcome of ICU patients. DESIGN: Retrospective, observational, cohort study in a Medical Intensive Care Unit. PATIENTS: Consecutive patients admitted during the years 2005 and 2006, and requiring a transfusion. We recorded patient's demographic data, number of RBC unit and age of each RBC, length of ICU, mortality during ICU stay. RESULTS: Five hundred and thirty-four patients were included with global mortality was 26.6%, length of stay in ICU six days (3-14) and SAPS II 48 (35-62). RBC equaling to 5.9 were transfused per patients (22.7%<14 days and 57.3%<21 days). The number of RBC was significantly higher in the dead patients group, but the rate of RBC stored less than 21 days was not different (54% versus 60%; p=0.21). In a multivariate logistic model, independent predictors of ICU death were SAPS II (OR=1.02 per point, p<0.001), number of RBC (OR=1.08 per RBC, p<0.001), length of stay in ICU (p<0.001). Similar results were obtained while introducing the age of RBC as time dependent covariates in a multivariate Cox's model. CONCLUSIONS: RBC transfused in our ICU are old. The ICU outcome is independently associated with the number of leucodepleted RBC transfused, but not with their age.

Crystallographic structure and energetics of the Rh(1 0 0)-(3 × 1)-2O phase.

In this study we investigate the crystallographic structure of the Rh(1 0 0)-([Formula: see text])-2O phase by quantitative low energy electron diffraction (LEED) and scanning tunnelling microscopy as well as the energetics of the system applying density functional theory calculations (DFT). The ([Formula: see text]) structure forms upon exposing the clean Rh(1 0 0) surface to 1200 L of oxygen at 520 K. A full-dynamical LEED intensity analysis (Pendry R-factor [Formula: see text]) reveals an oxygen-induced shifted row-reconstruction of the rhodium top layer where every third Rh-row is displaced by half a surface lattice parameter along the [0 1 1]-direction. There are two oxygen atoms within the unit cell which assume threefold coordinated sites on both sides of the shifted Rh-row with one bond to the shifted and two bonds to the unshifted rows. DFT calculations yield a total energy gain of 0.27 eV per oxygen atom compared to adsorption on the unreconstructed surface. This by far overcompensates the energetic penalty of 0.10 eV per oxygen atom for shifting the Rh-row and thus drives the substrate reconstruction. A coadsorption of oxygen at remaining regular sites of the substrate is not observed in experiment and is found to be energetically unfavorable.

Experimental vaccine induces Th1-driven immune responses and resistance to Neisseria gonorrhoeae infection in a murine model.

Female mice were immunized intravaginally with gonococcal outer membrane vesicles (OMVs) plus microencapsulated interleukin-12 (IL-12), and challenged using an established model of genital infection with Neisseria gonorrhoeae. Whereas sham-immunized and control animals cleared the infection in 10-13 days, those immunized with OMV plus IL-12 cleared infection with homologous gonococcal strains in 6-9 days. Significant protection was also seen after challenge with antigenically distinct strains of N. gonorrhoeae, and protective anamnestic immunity persisted for at least 6 months after immunization. Serum and vaginal immunoglobulin G (IgG) and IgA antibodies were generated against antigens expressed by homologous and heterologous strains. Iliac lymph node CD4+ T cells secreted interferon-γ (IFNγ), but not IL-4, in response to immunization, and produced IL-17 in response to challenge regardless of immunization. Antigens recognized by immunized mouse serum included several shared between gonococcal strains, including two identified by immunoproteomics approaches as elongation factor-Tu (EF-Tu) and PotF3. Experiments with immunodeficient mice showed that protective immunity depended upon IFNγ and B cells, presumably to generate antibodies. The results demonstrated that immunity to gonococcal infection can be induced by immunization with a nonliving gonococcal antigen, and suggest that efforts to develop a human vaccine should focus on strategies to generate type 1 T helper cell (Th1)-driven immune responses in the genital tract.

[Cardiogenic shock due to acute myocarditis complicating leptospirosis]. / Choc cardiogénique par myocardite aiguë révélant une leptospirose.

A 48 year old man was admitted to the intensive care unit with septicaemic shock associated with febrile jaundice and anuric renal failure. Within hours, he developed cardiogenic shock with multi-organ failure due to an acute myocarditis refractory to catecholamines and requiring intra-aortic balloon pumping. The diagnosis was an ictero-haemorrhagic leptospirosis, the outcome of which was finally favourable. Myocarditis is an underestimated complication of leptospirosis because it is often symptomless. The main signs are arrhythmias, conduction defects and ST-T wave abnormalities which have little clinical expression. The disease may progress and is sometimes fatal. Leptospirosis myocarditis should therefore be carefully considered because of its potential severity and its reversibility with appropriate antibiotic therapy and also the necessity of initial management in a specific infrastructure.

Retinoic acid receptor gamma mediates topical retinoid efficacy and irritation in animal models.

Among retinoic acid receptors (RARs) alpha, beta, and gamma, the messenger RNA level of RAR-gamma is the most readily detectable by Northern blotting in human and mouse skin. This observation suggests that RAR-gamma may play a critical role in the modulation of the therapeutic benefits and side effects of retinoids in skin. To test this hypothesis, 11 RAR-gamma selective retinoids were synthesized based on three related structures. Each compound was found to prefer RAR-gamma when assessed by retinoid-induced transcriptional activity (RAR-gamma > RAR-beta > RAR-alpha). The apparent Kd for binding to recombinant receptor protein was found to follow a similar trend. To correlate this receptor selectivity with in vivo activity, the compounds were tested topically in the Rhino mouse utriculi reduction and rabbit irritation models, two assays widely used to screen retinoids for efficacy and side effects, respectively. The results indicated that for these compounds, both efficacy in the utriculi reduction assay and irritation potential in rabbits correlated positively with the RAR-gamma transactivation activity, with r2 of 0.9 and 0.8, respectively. These data suggest that RAR-gamma is an important regulator of retinoic acid efficacy in skin and further, that the irritation associated with the use of retinoids is most likely a receptor-mediated process.

Insulin-like growth factor-I as a reflection of body composition, nutrition, and puberty in sixth and seventh grade girls.

Large variations in nutritional intake have profound effects on the GH-insulin-like growth factor-I (IGF-I) axis in children and adults, but the effect of normal variations in nutrition on IGF-I concentrations is largely unstudied, particularly during puberty. We measured serum IGF-I concentrations in 325 sixth and seventh grade girls (12.4 +/- 0.7 yr) at the beginning of a multisite school-based health curriculum. The mean serum IGF-I level among the 243 girls with complete data was 573 +/- 244 micrograms/L. Pubertal stage was significantly associated with IGF-I (P less than 0.0001, by analysis of variance). Mean concentrations rose from 427 +/- 198 micrograms/L among those at the earliest pubertal stages to 639 +/- 219 micrograms/L among the mature girls. After adjusting for the association with the stage of pubertal development, serum IGF-I was not significantly associated with measures of body composition (body mass index, triceps skin fold thickness, waist/hip ratio, height, and weight). Additionally, IGF-I concentrations were not associated with nutritional intake (total calories, total protein, total fat, and total carbohydrate) or such measures of nutrition as serum iron, hemoglobin, red cell mean corpuscular volume, white cell count, and cholesterol. IGF-I concentrations, however, were significantly correlated with transferrin concentrations, another possible index of nutritional status (r = 0.29; P less than 0.0001). IGF-I is not a clinically useful index of nutritional status among normal pubertal girls.

Pubertal stage and panic attack history in sixth- and seventh-grade girls.

OBJECTIVE: Although the incidence of first panic attacks appears to peak during adolescence, little is known about which features of adolescence contribute to the risk of a first panic episode. The purpose of this study was to compare the relative importance of age and pubertal stage in explaining the occurrence of panic attacks in adolescents. METHOD: From a school-based sample of sixth- and seventh-grade girls, 754 subjects completed both a structured clinical interview determining history of one or more panic episodes and a self-assessment of Tanner stages of pubertal development. A multiple logistic regression analysis was performed with panic attack history as the dependent variable and pubertal stage, age, and their interaction as the independent variables. RESULTS: A history of one or more four-symptom panic attacks was found in 5.3% of the girls (N = 40). After age was controlled for, pubertal stage was significantly related to panic attack history. At each age, higher rates of panic attacks were found in the more physically mature girls. CONCLUSIONS: Pubertal stage, after adjustment for the effects of age, appears to predict panic attack occurrence in young adolescent girls. Understanding the link between puberty and panic may offer clues regarding the onset and etiology of panic attacks.

Retinoic acid receptor beta,gamma-selective ligands: synthesis and biological activity of 6-substituted 2-naphthoic acid retinoids.

In search for retinoic acid receptor (RAR) selective ligands, a series of 6-substituted 2-naphthoic acid retinoids were synthesized and evaluated in vitro in a transactivation assay and a competition binding assay for all RARs. These derivatives, in general, showed RAR beta,gamma selectivity. Among these naphthoic acids, oxime derivative 12 was identified as a potent RAR gamma-selective retinoid, while olefinic derivative 11 was found to be comparable to retinoic acid and slightly RAR beta,gamma selective. For the bioassays, a general correlation was observed between the binding affinity of the ligand to the receptors and the potency of the compounds in the transactivation assay. The structure-activity relationship of these naphthoic acids will be discussed.

Growth and intellectual development.

Data from the National Health Examination Survey (cycles II and III) provided a representative sample of 13,887 US youths (6 to 17 years of age) with which to examine the relationship between height (normalized for age and sex) and measures of intellectual development (Wechsler Intelligence Scale for Children) and academic achievement (Wide Range Achievement Test). Additionally, 2,177 subjects were studied first in cycle II and 2 to 5 years later in cycle III, forming a well-selected longitudinal study group in which to examine any association between linear growth and change in IQ scores. Wechsler Intelligence Scale for Children and Wide Range Achievement Test scores were significantly correlated with height in both cycle II and cycle III. However, no significant association between change in relative height and change in IQ scores could be detected in the longitudinal group. These data suggest that therapies designed to increase height are unlikely to alter measures of intellectual development or academic achievement.

Does television viewing increase obesity and reduce physical activity? Cross-sectional and longitudinal analyses among adolescent girls.

To examine the relationships between hours of television viewing and adiposity and physical activity among female adolescents, a cohort study with follow-up assessments 7, 14, and 24 months after baseline was conducted. All sixth- and seventh-grade girls (N = 971) attending four northern California middle schools were eligible to participate. Six hundred seventy-one students had sufficient data for baseline cross-sectional analyses, and 279 students in a no-intervention cohort had sufficient data for longitudinal analyses. The baseline sample had a mean age of 12.4 years and was 43% white, 22% Asian, 21% Latino, 6% Pacific Islander, 4% black, 2% American Indian, and 2% other. Hours of after-school television viewing, level of physical activity, and stage of sexual maturation were assessed with self-report instruments. Height, weight, and triceps skinfold thickness were measured and body mass index (ratio of weight [in kilograms] to height [in meters] squared) and triceps skinfold thickness were adjusted by level of sexual maturity for the analyses. Baseline hours of after-school television viewing was not significantly associated with either baseline or longitudinal change in body mass index or triceps skinfold thickness. Baseline hours of after-school television viewing was weakly negatively associated with level of physical activity in cross-sectional analyses but not significantly associated with change in level of physical activity over time. All results were essentially unchanged when adjusted for age, race, parent education, and parent fatness. Among adolescent girls, television viewing time appears to have only weak, if any, meaningful associations with adiposity, physical activity, or change in either over time.

Development of feeding practices during the first 5 years of life.

OBJECTIVE: To understand the transition from breast-and bottle-feeding to solid-feeding and factors that might affect the duration of breast- and bottle-feeding. DESIGN: Cohort followed up from birth with relatively well-educated, middle-class parents. SETTING: Community sample recruited from 3 suburban newborn nurseries (a teaching hospital, community hospital, and large health maintenance organization). PARTICIPANTS: One hundred ninety-one healthy full-term infants. MEASURES: Assessment of feeding practices through the ages of complete weaning from breast- and bottle-feeding. RESULTS: More than 90% of participants breast-fed for at least 2 weeks. Infants of older mothers were weaned from the breast later than infants of younger mothers. First-born infants were weaned from the breast earlier than later-born infants. Eighty-four percent of infants bottle-fed at some time during the first year of life. More than 40% of the cohort was still receiving bottles at 24 months of age, 16% at 36 months, and 8% at 48 months. The duration of breast- and bottle-feeding was related to maternal work status; mothers who returned to work during the first 3 months postpartum weaned sooner from the breast and later from the bottle than women who returned to work after 3 months postpartum. CONCLUSIONS: The frequency of late bottle-weaning in this well-educated, middle-class cohort was unexpected and was related to the timing of the mother's return to work. The impact of prolonged bottle-feeding on later growth and adiposity deserves further investigation.

Timing and rate of sexual maturation and the onset of cigarette and alcohol use among teenage girls.

OBJECTIVE: To test the hypothesis that the patterns of pubertal progression, early vs late puberty and fast vs slow, are associated with the age at which girls start to drink alcohol and smoke cigarettes. DESIGN: The study included 1463 female students, 10.7 to 18.2 years of age, who were assessed five times during the 2.7-year study. Data regarding pubertal stage, alcohol use, and cigarette use were obtained at each assessment. These data were used to calculate two indexes of pubertal development, the age at which the midpoint of puberty was achieved and the rate of progression through puberty, and the ages when each subject first drank, first drank moderate amounts of alcohol, and first smoked. RESULTS: Girls with earlier puberty (midpoint < 12.2 years) first reported drinking any alcohol at a median age of 12.5 years, 0.7 years younger than girls whose puberty was later. Similarly, girls with earlier puberty reported drinking moderate amounts of alcohol at a median age of 13.7 years, 0.9 years younger than girls with later puberty. Girls with earlier puberty further reported first smoking cigarettes at a median age of 12.8 years, 0.6 years younger than girls with later puberty. The rate of pubertal progression was significantly associated only with the age when girls first drank moderate amounts of alcohol. CONCLUSION: Earlier puberty is associated with a younger age of onset for both drinking and smoking among adolescent girls.

Predicting children's reported eating disturbances at 8 years of age.

OBJECTIVES: To examine differential parental influences on eating attitudes and behaviors of 8-year-old children with a specific focus on gender effects and to assess the specificity of this relationship. METHOD: One hundred eight infants were monitored from birth and interviewed at age 8 for eating disturbances and negative affect with an adaptation of the McKnight Risk Factor Survey. Parental measures included the Three Factor Eating Questionnaire subscales Disinhibition and Restraint as well as body mass index, assessed at study entry. RESULTS: No gender differences were found for frequencies of children's self-reported eating disturbances. Higher maternal restraint scores predicted worries about being too fat in girls but not in boys. Higher maternal disinhibition scores also differentially predicted weight control behaviors in their daughters. Negative affect in the child was (weakly) predicted by higher maternal body mass index. No association between paternal predictors of disturbed eating and the child's eating disturbances and negative emotionality was found. CONCLUSIONS: The impact of maternal eating disorders and disturbances is much stronger than that of fathers and is specifically directed at their daughters. The clinical importance of these disturbances in terms of precursors of adolescent eating disorders has to be determined by monitoring the sample through puberty.

Psychiatric risk associated with early puberty in adolescent girls.

OBJECTIVE: This study prospectively evaluated the relationship between early puberty and the onset of internalizing symptoms and disorders in adolescent girls. METHOD: The sample was drawn from 1,463 sixth-, seventh-, and eighth-grade girls who participated in a longitudinal school-based study of growth and development. Pubertal stage was determined by self-assessment of Tanner stage. Psychiatric assessments included self-report instruments and structured diagnostic interviews. Survival methods were utilized for data analysis. RESULTS: Girls with onset of internalizing symptoms were on average 5 months earlier in pubertal development than those who were asymptomatic (p < .001). In addition, girls with earlier maturation (earliest quartile) were more likely to develop internalizing symptoms than were nonearly matures (hazard ratio = 1.8, confidence interval = 1.2, 2.7). In a subsample of girls followed into high school, early-maturing girls were at marginally higher risk (p < .10) for developing internalizing disorders by the study's end. The highest risk for internalizing disorders was for those girls with both early puberty and prior internalizing symptoms (odds ratio = 3.3). CONCLUSION: Early puberty increases the risk of internalizing symptoms and perhaps internalizing disorders in adolescent girls.

Breastfeeding attitudes and knowledge of pediatricians-in-training.

A 15-minute questionnaire was administered to the pediatric housestaff in an academic training program to assess their breastfeeding attitudes, knowledge, and confidence to manage breastfeeding problems. Questionnaires were self-administered and anonymous. The participation rate was 53% (n = 29). Overall, the study participants indicated a supportive attitude toward breastfeeding (2.6 on a 6-point scale where 1 = most supportive and 6 = least supportive). Women agreed more strongly than men that pediatricians should strongly encourage mothers to breastfeed and disagreed more strongly than men that breastfeeding is instinctive. Although supportive of breastfeeding, the housestaff in this study were not knowledgeable regarding breastfeeding management, answering only 53% of the questions correctly. Their self-confidence in this area was appropriately low, with only 14% of the total sample describing themselves as "confident" or "very confident" to manage common breastfeeding problems. Pediatricians-in-training have extremely limited knowledge of breastfeeding management. To be truly supportive of breastfeeding, pediatricians should receive didactic and clinical training in breastfeeding management.

Weight concerns influence the development of eating disorders: a 4-year prospective study.

The authors examined factors prospectively associated with age of onset of partial syndrome eating disorders over a 4-year interval in a community sample (N = 877) of high school-age adolescent girls. Four percent developed a partial syndrome eating disorder over the interval. A measure of weight concerns was significantly associated with onset in a multivariate Cox proportional hazard analysis (p < .001). Girls scoring in the highest quartile on the measure of weight concerns had the highest incidence (10%) of partial syndrome onset, whereas none of the girls in the lowest quartile developed eating disorder symptoms. This finding is consistent with both theoretical and clinical perspectives and may represent a useful step toward the establishment of a rational basis for the choice of a prevention intervention target.