Separation and detection of siderophores produced by marine bacterioplankton using high-performance liquid chromatography with electrospray ionization mass spectrometry

High-performance liquid chromatography-electrospray ionization mass spectrometry was applied to the detection of the iron(III) complexes of the hydroxamate siderophores rhodotoluric acid, deferrioxamine B, and deferrichrome. Separation of the iron(III) complexes was obtained using a polystyrene-divinylbenzene stationary phase. The retention and responses of ferrioxamine and ferrichrome were optimal when a gradient elution program with methanol and 0.1% (v/v) formic acid as the mobile phases was used. These conditions were also suitable for the retention and separation of the uncomplexed ligands. Retention of iron(III) rhodotoluate was improved when formic acid was replaced by the ion-pairing reagent heptafluorobutyric acid (0.1%). Detection limits for the ferric complexes, defined as 3 SD of the lowest determined standard, were 26 nM for iron(III) rhodotoluate, 0.23 nM for ferrioxamine, and 0.40 nM for ferrichrome. A protocol for the solid-phase extraction of these hydroxamate siderophores from seawater was developed and applied to the extraction of siderophores from enriched incubated seawater samples.     

The influence of sad mood on cognition.

Neuroimaging has identified an overlapping network of brain regions whose activity is modulated by mood and cognition. Studies of depressed individuals have shown changes in perception, attention, memory, and executive functions. This suggests that mood has a pervasive effect on cognition. Direct evidence of the effect of sad mood on cognition is surprisingly limited, however. Published studies have generally addressed a single cognitive ability per study because the fleeting nature of laboratory-induced mood precludes extended testing, and robust findings are limited to mood effects on memory for emotional stimuli. In this study, sad mood was induced and prolonged, enabling the effects of mood to be assessed for an array of abilities, including those that share neural substrates with sad mood and those affected by depression. Sad mood affected memory for emotional words and facial emotion recognition, but not the other processes measured, with a significant nonuniformity of effect over tasks. These results are consistent with circumscribed effects of sad mood on certain emotion-related cognitive processes, but not on cognition more generally. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Catalytic Effect of CaF2 Nanoparticles on Sintering Behavior of Kaolin-Based Materials

The present work represents preliminary results concerning the effect of nanometric CaF₂ particles on the sintering behavior of kaolin. The nanoparticles were synthesized using aqueous solutions of CaCl₂ dissolved with an organic dispersant and HF. The morphology and particle size of the obtained nanoparticles were square-like, having a mean length of 25 nm. Kaolin was mixed with different amounts of nanometric CaF₂ (from 0.625 to 5.0 wt%) and the mixtures were milled, pressed, and sintered. From sintering experiments, it was observed that additions of CaF₂ nanoparticles in kaolin clay could shift the phase transition temperatures to lower values. Specifically, the densification temperature could be reduced by almost 150°C when 2.5 wt% of CaF₂ was incorporated. Besides, adding 1.25% of nanometric CaF₂ can achieve that compressive strength augments from 125 to 185 MPa in kaolin samples sintered at 1200°C, meaning an improvement of 40% in the properties of the final material.     

Bender-Gestalt Test performance in senile dementia of the Alzheimer type.

Bender-Gestalt Test performances of 144 persons with very mild, mild, or moderate senile dementia of the Alzheimer type (SDAT) and 96 healthy older adults ranging in age from 63 to 95 yrs were compared. Total scores and error types according to the modified Hutt-Briskin scoring system are reported. The Bender-Gestalt Test does not appear to be useful in differentiating very mild or mild SDAT from normal aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cofiring from the TVA public power perspective

The Tennessee Valley Authority (TVA), created by Act of Congress in 1933, has responsibility for generating electricity, providing flood control, and promoting agricultural and industrial development for the Tennessee Valley. In the generation of electricity, TVA initially developed extensive hydroelectric facilities throughout the valley and, subsequently, extensive fossil and nuclear facilities. In the changing regulatory and economic environment associated with electricity generation, TVA has created the Public Power Institute (PPI). The PPI has responsibility for advancing energy generation and pollution reduction; it has responsibility for renewable energy development. In carrying out its renewable energy commitment, the PPI extends the leadership in biomass cofiring started in 1992, with studies and testing performed in cooperation with the Electric Power Research Institute at such locations as the Kingston Fossil Plant and the Allen Fossil Plant. It extends the activities associated with using tire-derived fuel at the Allen Fossil Plant. Through the PPI, TVA will continue to take a leadership role in the development of biomass systems.     

Influence of Dekkera bruxellensis on the contents of anthocyanins,organic acids and volatile phenols of Dão red wine

The anthocyanin, organic acid and volatile phenol compositions of red wine obtained from Touriga Nacional grapes growing in the Dão region (Portugal) were determined by HPLC/DAD, HPLC/UV and GC/FID, respectively. By these means, nine anthocyanic compounds (malvidin-3,5-O-diglucoside, cyanidin-3-O-galactoside, cyanidin-3-O-glucoside, peonidin-3-O-glucoside, malvidin-3-O-glucoside, delphinidin, cyanidin, pelargonidin and malvidin), six organic acids (ketoglutaric, tartaric, malic, quinic, lactic and shikimic acids) and two volatile phenols (4-ethylguaiacol and 4-ethylphenol) were identified and quantified. Malvidin-3-O-glucoside, the pair lactic plus shikimic acids and 4-ethylguaiacol were the main anthocyanin, organic acids and volatile phenol, respectively. The effects of nine different Dekkera bruxellensis strains on these chemical parameters were also evaluated. The results obtained indicate that some strains of D. bruxellensis yeast are able to cause deterioration of red wine from the Dão region during its maturation by the production of volatile phenols, namely 4-ethylphenol.     

Self-produced locomotion and the development of responsiveness to linear perspective and texture gradients.

Replicated and extended research on the development of sensitivity to the depth cues of linear perspective and texture gradients by using a more sensitive method (Experiment 1) and by investigating the role of self-produced locomotion in facilitating the onset of sensitivity to information (Experiment 2). Using a method similar to Yonas, Granrud, Arterberry, and Hanson (1986), infants' reaching to the pictorially closer object served as the dependent measure. Changes in methodology provided an increase in the difference between 7-month-olds' monocular and binocular reaching performance, but 5-month-olds failed to show evidence of sensitivity to the depth cues investigated. Experiment 2 found no difference in monocular reaching performance among 7-month-old infants with varying degrees of locomotor experience, suggesting that self-produced locomotion may not play a role in facilitating the onset of sensitivity to static-monocular depth information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Occurence of Culturable Vibrio cholerae from Lake Victoria,and Rift Valley Lakes Albert and George,Uganda

Vibrio cholerae, a bacterium that causes cholera, poses a human health risk when consumed via untreated or contaminated water. Monthly investigations into the presence of V. cholerae from Lakes Albert, George and Victoria were conducted, with the goal being to examine the relationship between the occurrences of V. cholerae with various water quality parameters at fish landing sites in major water bodies in Uganda. The pH, temperature and electrical conductivity were measured at three fishing sites in each of the three study lakes; namely Gabba in Lake Victoria, Butiaba in Lake Albert and Kayanzi in Lake George. The pH values varied from 7.76 to 9.36 at Butiaba, 8.68 to 9.85 at Kayanzi and 6.6 to 9.88 at Ggaba. The temperature ranged from 17.9 to 32.3 °C at Butiaba, 22.5 to 29 °C at Kayanzi and 18.2 to 30.5 °C at Ggaba. The electrical conductivity ranged from 129.2 to 984 μS cm^?1 at Butiaba, 658 to 1090 μS cm^?1 at Kayanzi and 119 to 218 μS cm^?1 at Ggaba, for Lakes Albert, George and Victoria, respectively. Enrichment techniques were used to detect culturable V. cholerae on TCBS culture media. Seventy‐five (75%) of the samples (n = 90) were positive for V. cholera. The occurrence of V. cholerae was positively associated with water quality parameters over the 10‐month period of study. Vibrio cholerae was more frequently detected during the dry season (warmer) than during the wet season. These study results suggest the investigated study lakes are natural reservoirs for V. cholerae.     

Developing conceptual understanding and procedural skill in mathematics: An iterative process.

The authors propose that conceptual and procedural knowledge develop in an iterative fashion and that improved problem representation is 1 mechanism underlying the relations between them. Two experiments were conducted with 5th- and 6th-grade students learning about decimal fractions. In Experiment 1, children's initial conceptual knowledge predicted gains in procedural knowledge, and gains in procedural knowledge predicted improvements in conceptual knowledge. Correct problem representations mediated the relation between initial conceptual knowledge and improved procedural knowledge. In Experiment 2, amount of support for correct problem representation was experimentally manipulated, and the manipulations led to gains in procedural knowledge. Thus, conceptual and procedural knowledge develop iteratively, and improved problem representation is 1 mechanism in this process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)