Ubiquitous atmospheric production of organic acids mediated by cloud droplets.

Atmospheric acidity is increasingly determined by carbon dioxide and organic acids1-3. Among the latter, formic acid facilitates the nucleation of cloud droplets4 and contributes to the acidity of clouds and rainwater1,5. At present, chemistry-climate models greatly underestimate the atmospheric burden of formic acid, because key processes related to its sources and sinks remain poorly understood2,6-9. Here we present atmospheric chamber experiments that show that formaldehyde is efficiently converted to gaseous formic acid via a multiphase pathway that involves its hydrated form, methanediol. In warm cloud droplets, methanediol undergoes fast outgassing but slow dehydration. Using a chemistry-climate model, we estimate that the gas-phase oxidation of methanediol produces up to four times more formic acid than all other known chemical sources combined. Our findings reconcile model predictions and measurements of formic acid abundance. The additional formic acid burden increases atmospheric acidity by reducing the pH of clouds and rainwater by up to 0.3. The diol mechanism presented here probably applies to other aldehydes and may help to explain the high atmospheric levels of other organic acids that affect aerosol growth and cloud evolution.

Bond lengths in free molecules of buckminsterfullerene, c60, from gas-phase electron diffraction.

Electron diffraction patterns of the fullerene C(60) in the gaseous state have been obtained by volatilizing it from a newly designed oven-nozzle at 730 degrees C. The many peaks of the experimental radial distribution curve calculated from the scattered intensity are completely consistent with icosahedral symmetry for the free molecule. On the basis of this symmetry assumption, least-squares refinement of a model incorporating all possible interatomic distances led to the values r(g)(C(1)-C(2)) = 1.458(6) angstroms (A) for the thermal average bond length within the five-member ring (that is, for the bond fusing five- and six-member rings) and r(g)(C(1)-C(6)) = 1.401(10) A for that connecting five-member rings (the bond fusing six-member rings). The weighted average of the two bond lengths and the difference between them are the values 1.439(2) A and 0.057(6) A, respectively. The diameter of the icosahedral sphere is 7.113(10) A. The uncertainties in parentheses are estimated 2sigma values.

C60 rotation in the solid state: dynamics of a faceted spherical top.

The rotational dynamics of C(60) in the solid state have been investigated with carbon-13 nuclear magnetic resonance ((13)C NMR). The relaxation rate due to chemical shift anisotropy (1/9T1(CSA)(1)) was precisely measured from the magnetic field dependence of T(1), allowing the molecular reorientational correlation time, tau, to be determined. At 283 kelvin, tau = 9.1 picoseconds; with the assumption of diffusional reorientation this implies a rotational diffusion constant D = 1.8 x 10(10) per second. This reorientation time is only three times as long as the calculated tau for free rotation and is shorter than the value measured for C(60) in solution (15.5 picoseconds). Below 260 kelvin a second phase with a much longer reorientation time was observed, consistent with recent reports of an orientational phase transition in solid C(60). In both phases tau showed Arrhenius behavior, with apparent activation energies of 1.4 and 4.2 kilocalories per mole for the high-temperature (rotator) and low-temperature (ratchet) phases, respectively. The results parallel those found for adamantane.

Specific tropism of HIV-1 for microglial cells in primary human brain cultures.

Human immunodeficiency virus (HIV) frequently causes neurological dysfunction and is abundantly expressed in the central nervous system (CNS) of acquired immunodeficiency syndrome (AIDS) patients with HIV encephalitis or myelopathy. The virus is found mostly in cells of the monocyte-macrophage lineage within the CNS, but the possibility of infection of other glial cells has been raised. Therefore, the effects of different HIV-1 and HIV-2 strains were studied in primary cultures of adult human brain containing microglial cells, the resident CNS macrophages, and astrocytes. These cultures could be productively infected with macrophage-adapted HIV-1 isolates but not with T lymphocyte-adapted HIV-1 isolates or two HIV-2 isolates. As determined with a triple-label procedure, primary astrocytes did not express HIV gag antigens and remained normal throughout the 3-week course of infection. In contrast, virus replicated in neighboring microglial cells, often leading to their cell fusion and death. The death of microglial cells, which normally serve immune functions in the CNS, may be a key factor in the pathogenesis of AIDS encephalitis or myelopathy.

[Mortality risk factors in ventilator associated pneumonia]. / Factores de riesgo para mortalidad en neumonía asociada a ventilación mecánica.

OBJECTIVE: to identify lethality and mortality rates and, mortality risk factors in ventilator associated pneumonia (VAP) on 114 patients treated between 2000 and 2007. METHOD: Twenty five risk factors were analyzed, emphasizing age, gender, APACHE score, associated diseases, hypotension at intake, coma, hospitalization time, length of time of ventilation, emergency intubation, reintubation, previous antibiotics, and resistant microrganisms. RESULTS: Lethality was 25.4 %, and mortality was 2.4 %. Association between lethality, and APACHE score was found (p: 0.04). Critical APACHE value was 22. Also, in early pneumonia, association between lethality and nasogastric tube (p: 0.01, I.C. 95 % 1.39 - 6.35) was found. No association with late pneumonia was found among mortality and clinical practices. Death's RR (relative risk) increase in following values with: previous neurological disease 2.7 (p: 0.15, IC 95 % 1.15 - 6.5), neurological comaRR 2 (p: 0.2, IC 95 % 0.54 - 7.53). Nevertheless, at multivariate analysis no mortality risk factors were identified. Fair association with time in ICU (p: 0.051 IC 95 % 0.99 - 1.17) and, male sex (p: 0.051, IC 95 % 0.99 - 6.72) was found. CONCLUSIONS: We observed multiple factors associated to mortality in VAP: use of nasogastric catheter, longer stay in ICU and male sex.

Slow oscillatory transcranial direct current stimulation (so-tDCS) during slow wave sleep has no effects on declarative memory in healthy young subjects.

BACKGROUND: The manipulation of specific brain oscillations by applying transcranial electrical stimulation techniques in order to enhance memory processes during sleep has become an intriguing field of research. A seminal study found a positive effect of slow-oscillatory transcranial direct current stimulation (so-tDCS) on sleep-dependent consolidation of declarative memories. Since then several studies have tried to replicate this result with inconsistent findings. OBJECTIVE/HYPOTHESIS: This study aimed to reexamine effects of so-tDCS on declarative memory observed in young participants based on a previously described stimulation protocol used in elderly subjects. METHODS: 23 healthy participants (mean ±â€¯SD: 23.2 ±â€¯1.9 years; 13 women) completed a word-pair test and a sequential finger tapping test before and after sleep. Participants received anodal so-tDCS bifrontaly at a frequency of 0.75 Hz or sham stimulation during NREM sleep N2, following a double-blind, placebo controlled, counterbalanced, randomized crossover design. Data were analyzed with respect to possible effects of stimulation on memory performances, sleep staging, spindle densities and EEG power in eight frequency bands. RESULTS: Stimulation had no significant effect on sleep dependent memory consolidation or on sleep macro- and microstructure. Independent of stimulation, procedural memory performances increased and declarative memory performances decreased overnight. This decline was less pronounced when participants had more than one learning opportunity. Fast parietal but not slow frontal spindle densities diminished from baseline to stimulation-free intervals under both stimulation conditions. CONCLUSION: The present study could not reproduce the results of the seminal study in young subjects, but it is consistent with results observed in elderly subjects using the same protocol. Irrespective of stimulation, re-encoding opportunities in the word-pair test had an impact on memory strength and retrieval performance.

NDM-1 carbapenemase in Acinetobacter baumannii sequence type 32 in Ecuador.

OBJECTIVES: To describe a clinical case of Acinetobacter baumannii sequence type (ST) 32 harbouring a New Delhi metallo-ß-lactamase (NDM) in Ecuador. METHODS: We used multilocus sequence typing (MLST) to confirm the bacterial species and the sequence type of an A. baumannii isolate. We used synergy with the imipenem-EDTA disc method and the carbapenem inactivation method (CIM) to determine carbapenemase production; the presence of a carbapenemase gene was confirmed by PCR amplification and amplicon sequencing. RESULTS: Molecular characterization revealed the presence of A. baumannii ST32 harbouring the bla NDM-1 gene in Ecuador. The bla NDM-1 gene was isolated through PCR and amplified from a purified plasmid. CONCLUSIONS: To the best of our knowledge, this is the first report of A. baumannii ST32 harbouring the bla NDM-1 gene.

Giant exchange coupling and field-induced slow relaxation of magnetization in Gd2@C79N with a single-electron Gd-Gd bond.

Magnetic properties of the azafullerene Gd2@C79N are studied by SQUID magnetometry. The effective exchange coupling constant jGd,e between the Gd spins and the spin of unpaired electron residing on the single-electron Gd-Gd bond is determined to be 170 ± 10 cm-1. Low temperature AC measurements revealed field-induced millisecond-long relaxation of magnetization.

Exposure setups for laboratory animals and volunteer studies using body-mounted antennas.

For two different in vivo exposure setups body-mounted antenna systems have been designed. The first setup is designed for investigation of volunteers during simulated mobile phone usage. The setup consists of a dual-band antenna for GSM/WCDMA with enhanced carrying properties, which enables exposure for at least 8 h a day. The 10 g averaged localised SAR--normalised to an antenna input power of 1 W--measured in the flat phantom area of the SAM phantom amounts to 7.82 mW g(-1) (900 MHz) and 10.98 mW g(-1) (1966 MHz). The second exposure setup is used for a laboratory behavioural study on rats. The design goal was a localised, well-defined SAR distribution inside the animals' heads at 900 MHz. To fulfil the biological requirements, a loop antenna was developed. For tissues around the ears, a localised SAR value of 50.12 W kg(-1) averaged over a mass of 2.2 g for an antenna input power of 1 W is obtained.

[Cost and outcome of hip's arthroplasty nosocomial infection. Case and control study]. / Costo y desenlace de la infección de artroplastía de cadera. Estudio de caso y control.

Case-control study for evaluation of cost and outcome of nosocomial surgical site infection in primary hip arthroplasty during a period of 5 years. Mean hospitalization time in the orthopedic service was 54 days for cases, and 13 days for control (p<0.05). Mean hospitalization time in Intensive Care Unit (ICU) was 1.1 days for cases. There were 0.83 post primary surgery interventions in cases, and a mean of 2.08 bacteriological cultures in each case. Controls didn't have hospitalizations in the ICU surgical reinterventions nor cultures necessary. The mean cost of infected patients was US $: 6,174.8. Mean cost in controls was US $: 2,354.7. The excess of cost due to infections was US $: 2,354.7 on the average. Outcomes in cases were: normal function 30.8%; moderate or serious sequelae 46.2%; death rate 15, 4%. The measured parameters contributed to raise case costs, and they caused an unsatisfactory outcome for two third of the patients.

Optimization and prediction of the electron-nuclear dipolar and scalar interaction in 1H and 13C liquid state dynamic nuclear polarization.

During the last 10-15 years, dynamic nuclear polarization (DNP) has evolved as a powerful tool for hyperpolarization of NMR and MRI nuclides. However, it is not as well appreciated that solution-state dynamic nuclear polarization is a powerful approach to study intermolecular interactions in solution. For solutions and fluids, the 1H nuclide is usually dominated by an Overhauser dipolar enhancement and can be significantly increased by decreasing the correlation time (τc) of the substrate/nitroxide interaction by utilizing supercritical fluids (SF CO2). For molecules containing the ubiquitous 13C nuclide, the Overhauser enhancement is usually a profile of both scalar and dipolar interactions. For carbon atoms without an attached hydrogen, a dipolar enhancement usually dominates as we illustrate for sp2 hybridized carbons in the fullerenes, C60 and C70. However, the scalar interaction is dependent on a Fermi contact interaction which does not have the magnetic field dependence inherent in the dipolar interaction. For a comprehensive range of molecular systems we show that molecules that exhibit weakly acidic complexation interaction(s) with nitroxides provide corresponding large scalar enhancements. For the first time, we report that sp hybridized (H-C) alkyne systems, for example, the phenylacetylene-nitroxide system exhibit very large scalar dominated enhancements. Finally, we demonstrate for a wide range of molecular systems that the Fermi contact interaction can be computationally predicted via electron-nuclear hyperfine coupling and correlated with experimental 13C DNP enhancements.

Time-of-day variations of indicators of attention: performance, physiologic parameters, and self-assessment of sleepiness.

BACKGROUND: A study was performed to analyze time-of-day variations of different indicators of attention and their interrelations. METHODS: After a sufficiently long all-night sleep 12 healthy non-sleep-deprived subjects ran through a test battery (Stanford Sleepiness Scale, Visual Analogue Scale, Critical Flicker Fusion Test [CFF], Visualization Test, Number Facility Test, Reaction Time, Pupillometry, and modified Multiple Sleep Latency Test) every 2 hours from 7:00 AM until 11:00 PM. Time-of-day variations were tested nonparametrically with Friedman's test for repeated measurements. Principal component factor analysis (of individually standardized values) was used to identify variable complexes with the same pattern of time-of-day variation. RESULTS: Statistically significant time-of-day variations were found for all variables, except for Fusion Frequency in CFF and Reaction Time. In factor analysis the physiologic parameters (pupillometric variables and sleep latencies) load on one factor, whereas the self-assessment scales, the Visualization Test, Number Faculty Test, and CFF load on the second factor. The variables that load primarily on factor 1 show peak levels of alertness immediately after getting up (at 7:00 AM) and again at 9:00 PM. Those variables that load primarily on factor 2 indicate a peak level of alertness around noon (11:00 AM-3:00 PM). CONCLUSIONS: Different aspects of attention follow different time-of-day variations. It is discussed, that these findings can be attributed to underlying circadian and homeostatic factors.

Schizophrenia: reduced signal-to-noise ratio and impaired phase-locking during information processing.

OBJECTIVE: This study was performed in order to clarify the mechanisms which underlie the reduced signal-to-noise of event-related potentials in schizophrenic patients. Specifically, we wanted to find out, whether it is reduced activation and/or synchronization (phase-locking) in specific frequency bands of the ongoing EEG which is related to the decreased signal amplitude and signal-to-noise ratio in schizophrenics. METHODS: We investigated 41 unmedicated schizophrenics (10 of them drug-naïve) and compared them with healthy control subjects (n = 233) as well as unmedicated subjects with schizotypal personality (n = 21), who were considered to be high-risk subjects for schizophrenia, and unmedicated depressive patients (n = 71). We measured event-related activity during an acoustical choice reaction paradigm and calculated the signal-to-noise ratio, signal power and noise for a time interval of 50-200 ms after stimulus presentation. Signal-to-noise ratio was calculated from the power of the averaged trials (signal power) divided by the mean power of the single trials minus the power of the average (noise power). Also, we performed a frequency analysis of the pre- and poststimulus EEG based on a factor analytical approach. Group comparisons were performed with ANCOVA. RESULTS: As expected, a decreased signal-to-noise ratio of evoked activity was found in the schizophrenic and a non-significant trend in the schizotypal subjects and the depressive patients. We were able to show that the observed decrease is due to a reduced signal power and an increase of absolute noise power. Frequency analysis of the evoked activity revealed that normals, schizophrenics schizotypal subjects and depressive patients increased theta/delta activity between pre- and poststimulus interval to a similar extend. However, this theta/delta-augmentation does not correlate with signal power in schizophrenics. Also, normals and depressive subjects augment coherence between both temporal lobes during information processing, which is not found in schizophrenics and schizotypal subjects. In contrast, these two groups augment frontal lobe coherence, which goes along with an increase of noise. CONCLUSIONS: Reduced stimulus-induced phase-locking and bitemporal coherence of cortically evoked activity but not a failure to activate the cortex may be responsible for the observed low signal-to-noise ratio during information processing in schizophrenics. Accordingly, schizophrenics increase noise after stimulus presentation instead of building up a signal. This is discussed in the framework of the theory of stochastic resonance.

Cortical activation, signal-to-noise ratio and stochastic resonance during information processing in man.

OBJECTIVES: The goal of this study was to determine the relation between EEG, event-related potentials and information processing as measured by an acoustical choice reaction time task. In particular, we wanted to find out to what extent reaction-time performance is related to the pre-stimulus EEG activity (frequency domain) and the magnitude of signal power as well as noise power (stimulus-uncorrelated activity) after the tones (time domain). MATERIALS AND METHODS: For parametrization, EEG-activity was factorized across pre-defined frequency bands and 19 electrode positions, applying spectral power and coherence analysis. Signal power was estimated by calculating the mean power of the evoked single sweeps. Noise power was computed by subtracting the latter minus the power of the average evoked potential. We investigated 254 healthy subjects who had to perform an acoustical choice reaction task during running EEG. RESULTS: In the frequency domain, it was found that high frontally pronounced delta-power in the pre-stimulus EEG correlates with fast reaction-time performance, which was regarded as the expression of a readiness potential in the frequency domain, reflecting increased cortical activation. In the time domain, fast reaction times were found to be correlated with the amplitude of the event-related potential N100 as well as with the signal power and signal-to-noise ratio of the evoked activity. This result pointed to the frequently described relation between evoked signals and information processing. In accordance with the theory of stochastic resonance, we also found a positive correlation between the magnitude of noise power after the stimulus and reaction-time performance. Besides, noise power was found to be positively correlated with pre-stimulus cortical activation (mainly in the delta and alphal frequency band), whereas no relation was found between pre-stimulus EEG and the signal power of the event-related activity, except for a weak relation to the alpha2 power. CONCLUSION: Our findings support the notion that information processing is not only dependent on signal strength but also on a certain amount of basic noise, reflecting the overall energy state of the brain.

Treating problem-solving deficits on an acute care psychiatric inpatient unit.

Neuropsychological deficits in problem-solving are commonly found in patients with schizophrenia and severe affective disorders. However, in an acute care setting, treatment efforts do not typically target these deficits, even though they can impede recovery. This study aimed to evaluate the effectiveness of short-term problem-solving remediation in acutely ill psychiatric inpatients. Twenty-eight psychiatric inpatients identified as having a verbal problem-solving deficit received 6 h of either verbal problem-solving remediation or placebo instruction. Before and after treatment a nurse rated the patient's psychiatric status and the patient completed verbal and nonverbal problem-solving tests, and a self-report rating of symptoms and ability to cope with symptoms. Both groups of patients improved on the measure of verbal problem solving, but those receiving problem-solving remediation improved significantly more. Both groups made symptomatic improvement, but the patients receiving problem-solving remediation made significantly more improvement on the measure of coping ability and the nurses rated them as more improved, both psychiatrically and with regard to coping skills. Verbal problem-solving deficits are responsive to short-term remediation in an acute care setting, and treatment effects may generalize to improve ability to cope with psychiatric symptoms.

Efficacy of imidacloprid for removal and control of fleas (Ctenocephalides felis) on dogs.

OBJECTIVE: To evaluate efficacy of a 9.1% (w/w) imidacloprid solution, applied topically, to remove fleas from dogs and the duration of residual flea control when dogs were exposed to continuing flea infestation. ANIMALS: 32 adult mixed-breed dogs. PROCEDURE: Dogs were allocated to 4 groups of 8 dogs each; dogs of 3 groups received a single dose of imidacloprid, and those of the fourth group received excipient. Each dog was infested with 100 adult fleas on study days -3, -1, 6, 13, 20, 27, and 33. Treatments were applied on day 0. Each dog was examined for live fleas on days -2, 1, 7, 14, 21, 28, and 34. Posttreatment efficacy was determined by comparing the mean number of live fleas remaining on the treated dogs with the mean number of live fleas remaining on the control dogs. RESULTS: All 3 imidacloprid dosages provided flea control > or = 96.9% one day after treatment. Maximal efficacy of all 3 dosages (99.1 to 100%) was observed at 7 days after treatment. Flea control with 3.75 mg of imidacloprid/kg of body weight ranged from 94.4 to 96.9% for days 14 to 28 and decreased to 91.6% by 34 days after treatment. Flea control with 7.5 and 10.0 mg of imidacloprid/kg was 97.8 to 100% through day 28. At day 34, dosages of 7.5 and 10.0 mg of imidacloprid/kg were 97.6 and 96.9% efficacious, respectively. CONCLUSION: 7.5 or 10.0 mg of imidacloprid/kg are equivalent and superior to 3.75 mg/kg for flea control over the course of a 34 day posttreatment period. CLINICAL RELEVANCE: Monthly imidacloprid application of 7.5 to 10 mg/kg will rapidly kill existing and reinfesting flea infestations on dogs and break the flea life cycle by killing adult fleas before egg production begins.

[Alkylating derivatives of 2-amino-2-deoxysugars and 1-methylamino-1-deoxypolyols (synthesis and experimental study)]. / Alkiliruiushchie proizvodnye 2-amino-2-dezoksisakharov i 1-metilamino-1-dezoksipoliolov (sintez i éksperimental'noe izuchenie).

A number of derivatives of 2-amino-2-deoxysaccharides and 1-methylamino-1-deoxypolyols acylated by cytotoxic phenylalkanic and amino acids were synthesized and experimentally tested for antitumor activity. Some compounds showed a high antitumor activity against plasmacytoma MOPC-406: a 2-fold increase in experimental animals survival and a 80--100% cure rate were observed. Physicochemical properties, particularly, stability in aqueous solution and antitumor activity of one of the most potent compounds--1-methylamino-1-deoxy-1-N[p-di(2-chloroethyl) aminophenylacetyl]-D-glucitol (Agluphen)--are described in detail.

Rhodium-Catalyzed Formation of Phosphorus-Boron Bonds: Synthesis of the First High Molecular Weight Poly(phosphinoborane).

An inorganic analogue of polystyrene, poly(phenylphosphinoborane) represents the first high molecular weight, well-characterized polymer with a backbone of alternating phosphorus and boron atoms. It is accessible by metal-catalyzed "dehydrocoupling" of a primary phosphane-borane adduct (see scheme).

Supramolecular Organometallic Polymer Chemistry: Self-Assembly of a Novel Poly(ferrocene)-b-polysiloxane-b-poly(ferrocene) Triblock Copolymer in Solution.

Micelles with unprecedented flowerlike arrangements of the poly(ferrocene) cores (shown in the TEM image) are among the supramolecular architectures generated in the self-assembly of a novel organometallic triblock copolymer from silicon-bridged [1]ferrocenophane monomers and [Me(2)SiO](3) in hexane, a solvent selective for the central polysiloxane block.