Efficient passivation of n-type and p-type silicon surface defects by hydrogen sulfide gas reaction.

An efficient surface defect passivation is observed by reacting clean Si in a dilute hydrogen sulfide-argon gas mixture (<5% H2S in Ar) for both n-type and p-type Si wafers with planar and textured surfaces. Surface recombination velocities of 1.5 and 8 cm s-1are achieved on n-type and p-type Si wafers, respectively, at an optimum reaction temperature of 550 °C that are comparable to the best surface passivation quality used in high efficiency Si solar cells. Surface chemical analysis using x-ray photoelectron spectroscopy shows that sulfur is primarily bonded in a sulfide environment, and synchrotron-based soft x-ray emission spectroscopy of the adsorbed sulfur atoms suggests the formation of S-Si bonds. The sulfur surface passivation layer is unstable in air, attributed to surface oxide formation and a simultaneous decrease of sulfide bonds. However, the passivation can be stabilized by a low-temperature (300 °C) deposited amorphous silicon nitride (a-Si:NX:H) capping layer.

Persistent inflammation, immunosuppression and catabolism syndrome (PICS) in critically ill children is associated with clinical outcomes: a prospective longitudinal study.

BACKGROUND: Persistent inflammation, immunosuppression and catabolism syndrome (PICS) has been described in critically ill adults and may contribute to unfavourable outcomes. The present study aimed to describe and characterise PICS in critically ill children (PICS-ped) and to verify its association with clinical outcomes. METHODS: A prospective longitudinal study was conducted in a paediatric intensive care unit (PICU) with children aged between 3 months and 15 years. PICS-ped, based on adult definition, was described. PICS-ped was defined as PICU length of stay >14 days; C-reactive protein > 10.0 mg L-1 ; lymphocytes <25%; and any reduction of mid-upper arm circumference Z-score. Clinical, demographic, nutritional status, nutrition therapy parameters and clinical outcomes were assessed. Statistical analysis comprised Mann-Whitney and Fisher's chi-squared tests, as well as logistic and Cox regression. P < 0.05 was considered statistically significant. RESULTS: In total, 153 children were included, with a median age of 51.7 months (interquartile range 15.6-123.4 months), and 60.8% male. The mortality rate was 10.5%. The prevalence of PICS-ped was 4.6%. Days using vasoactive drugs and days using antibiotics were associated with PICS-ped. PICS-ped was associated with mortality in crude (odds ratio = 6.67; P = 0.013) and adjusted analysis (odds ratio = 7.14; P = 0.017). PICS-ped was also associated with PICU and hospital length of stay, as well as duration of mechanical ventilation. Similar results were found in a subset of critically ill children who required mechanical ventilation for more than 48 h. CONCLUSIONS: Children with PICS-ped required antibiotics or vasoactive drugs for a longer period. PICS-ped was associated with poor clinical outcomes in critically ill children. More studies are needed to properly define PICS-ped for this population.

Local electronic structure of the peptide bond probed by resonant inelastic soft X-ray scattering.

The local valence orbital structure of solid glycine, diglycine, and triglycine is studied using soft X-ray emission spectroscopy (XES), resonant inelastic soft X-ray scattering (RIXS) maps, and spectra calculations based on density-functional theory. Using a building block approach, the contributions of the different functional groups of the peptides are separated. Cuts through the RIXS maps furthermore allow monitoring selective excitations of the amino and peptide functional units, leading to a modification of the currently established assignment of spectral contributions. The results thus paint a new-and-improved picture of the peptide bond, enhance the understanding of larger molecules with peptide bonds, and simplify the investigation of such molecules in aqueous environment.

Site-specific electronic structure of imidazole and imidazolium in aqueous solutions.

The occupied and unoccupied electronic structure of imidazole (C3N2H4) and imidazolium (C3N2H5+) in aqueous solutions is studied by X-ray emission spectroscopy (XES) and resonant inelastic soft X-ray scattering (RIXS). Both systems show distinct RIXS fingerprints with strong resonant effects. A comparison with calculated X-ray emission spectra of isolated imidazole and imidazolium suggests only a small influence of hydrogen bonding in the aqueous solution on the electronic structure of imidazole and imidazolium, and allows the attribution of specific spectral features to the non-equivalent nitrogen and carbon atoms in the molecules. In the case of nitrogen, this can also be achieved by site-selective resonant excitation. Furthermore, we find spectator shifts and symmetry selectivity in the RIXS spectra, as well as indications for rapid proton dynamics on the femtosecond timescale of the RIXS process, and derive the HOMO-LUMO gaps for the two molecules in aqueous solution.

X-ray Emission Spectroscopy of Proteinogenic Amino Acids at All Relevant Absorption Edges.

Nonresonant N K, O K, C K, and S L2,3 X-ray emission spectra of the 20 most common proteinogenic amino acids in their solid zwitterionic form are reported. They represent a comprehensive database that can serve as a reliable basis for the X-ray absorption spectroscopy (XES) studies of peptides and proteins. At the most important N and O K edges, clear similarities and differences between the spectra of certain amino acids are observed and associated with the specific chemical structure of these molecules and their functional groups. Analysis of these spectra allows the generation of spectral fingerprints of the protonated amino group, the deprotonated carboxylic group, and, using a building block approach, the specific nitrogen- and oxygen-containing functional groups in the side chains of the amino acids. Some of these fingerprints are compared to the spectra of reference compounds with the respective functional groups; they exhibit reasonable similarity, underlining the validity of the spectral fingerprint approach. The C K and S L2,3 XES spectra are found to be specific for each amino acid, in accordance with the different local environments of the involved C and S atoms, respectively.

Isotope Effects in the Resonant Inelastic Soft X-ray Scattering Maps of Gas-Phase Methanol.

The electronic structure of gas-phase methanol molecules (H3COH, H3COD, and D3COD) at atmospheric pressure was investigated using resonant inelastic soft X-ray scattering (RIXS) at the O K and C K edges. We observe strong changes of the relative emission intensities of all valence orbitals as a function of excitation energy, which can be related to the symmetries of the involved orbitals causing an angularly anisotropic RIXS intensity. Furthermore, all observed emission lines are subject to strong spectator shifts of up to -0.9 eV at the O K edge and up to -0.3 eV at the C K edge. At the lowest O K resonance, we find clear evidence for dissociation of the methanol molecule on the time scale of the RIXS process, which is illustrated by comparing X-ray emission spectra of regular and deuterated methanol.

"Building block picture" of the electronic structure of aqueous cysteine derived from resonant inelastic soft X-ray scattering.

The electronic structure of the amino acid L-cysteine in an aqueous environment was studied using resonant inelastic soft X-ray scattering (RIXS) in a 2D map representation and analyzed in the framework of a "building block" approach. The element selectivity of RIXS allows a local investigation of the electronic structure of the three functional groups of cysteine, namely, the carboxyl, amino, and thiol groups, by measuring at the O K, N K, and S L2,3 edges, respectively. Variation of the pH value allows an investigation of molecules with protonated and deprotonated functional groups, which can then be compared with simple reference molecules that represent the isolated functional groups. We find that such building blocks can provide an excellent description of X-ray emission spectroscopy (XES) and RIXS spectra, but only if all nearest-neighbor atoms are included. This finding is analogous to the building block principle commonly used in X-ray absorption spectroscopy. The building blocks show a distinct spectral character (fingerprint) and allow a comprehensive interpretation of the cysteine spectra. This simple approach opens the path to investigate the electronic structure of more complex biological molecules in aqueous solutions using XES and RIXS.

Complete determination of molecular orbitals by measurement of phase symmetry and electron density.

Several experimental methods allow measuring the spatial probability density of electrons in atoms, molecules and solids, that is, the absolute square of the respective single-particle wave function. But it is an intrinsic problem of the measurement process that the information about the phase is generally lost during the experiment. The symmetry of this phase, however, is a crucial parameter for the knowledge of the full orbital information in real space. Here, we report on a key experiment that demonstrates that the phase symmetry can be derived from a strictly experimental approach from the circular dichroism in the angular distribution of photoelectrons. In combination with the electron density derived from the same experiment, the full quantum mechanical wave function can thus be determined experimentally.

Prenatal diagnosis of 48,XYY, +21 ascertained through ultrasound anomalies.

During a routine ultrasound study on a fetus at 21 weeks, nuchal edema was noted. At 21 weeks, repeat ultrasound study at our unit showed scalp and neck edema and a femur length/biparietal diameter ratio below the mean. Transabdominal chorionic villus sampling identified a 48.XYY, +21 chromosome constitution. The fetus had normal internal/external genitalia and signs of Down syndrome.

Prenatal diagnosis of spina bifida: the fetal head shape as a clue

Realizamos uma ultra-sonografia de rotina durante a 24ª semana de gestaçäo de uma primipara de 22 anos, demonstrando-se uma anomalia do formato do crânio fetal. Repetimos a ultrasonografia na 26ª semana tendo sido confirmado um estreitamento na fossa anterior do crânio e um espinha bífica na regiäo lombro-sacra. As duas anomalias foram confirmadas no estudo anatomopatológico do feto. Ressaltamos a importância do sinal ultra-sonográfico descrito uma vez que, no Brasil, as dosagens de alfafetoproteína, quer no líquido amniótico ou no soro materno, exibem padröes de confiabilidade para fins de diagnóstico pré-natal

Comparison of lecithin: sphingomyelin ratio, fluorescence polarization, and phosphatidylglycerol in the amniotic fluid in the prediction of respiratory distress syndrome.

The significance of the lecithin sphingomyelin (L:S) ratio as a determining factor in fetal lung maturity is well established. An L:S ratio of greater than 2.0 to 2.5 is indicative of fetal lung maturity in most assays. The fluorescence polarization method (fluorescence polarization less than 0.320) has been associated with fetal lung maturity. The presence of phosphatidylglycerol in amniotic fluid has been related to fetal lung maturity and the absence of respiratory distress syndrome. Amniotic fluid samples from 235 amniocentesis procedures and vaginal pool collection at varying gestational ages were analyzed for L:S ratio, fluorescence polarization, and phosphatidylglycerol. All samples with meconium or hemolyzed blood contamination and selected complications of pregnancy were removed from the study. A positive result will predict the absence of respiratory distress syndrome, and a negative result will predict the presence of respiratory distress syndrome. Correlation of L:S ratio, fluorescence polarization, and phosphatidylglycerol were favorable. False-positive results in three (3.3%) fluorescence polarization samples were noted, whereas there were none (0%) in the L:S ratio sample and one (1%) in the phosphatidylglycerol sample. Twenty-four (77.4%), 28 (73.7%), and 37 (77%) were the number of false-negatives in the fluorescent polarization, L:S ratio, and phosphatidylglycerol samples. Fluorescence polarization, L:S ratio, and presence of phosphatidylglycerol compare favorably as fetal lung maturity tests. The prediction of respiratory distress syndrome is as sensitive with the three modalities. The specificity and the predictive value of a positive test is more favorable with L:S ratio and phosphatidylglycerol.

Carcinoma de celulas claras do endometrio em jovem de raca negra. / Clear cells carcinoma of the endometrium in a young black woman

E relatado um caso de carcinoma de celulas claras do endometrio em jovem nulipara de raca negra, fato interessante, visto se tratar de patologia que acomete na maioria das vezes pacientes de 5a. e 6a. decadas e de raca branca. A terapeutica cirurgica adotada na epoca em que a paciente foi atendida foi mais agressiva em virtude de que o conceito entao vigente era de que o carcinoma de celulas claras do endometrio apresentava maior agressividade e maior mortalidade, o que ja nao prevalece nos trabalhos mais modernos