Aggregation behaviour of a water-soluble ammonium-functionalized polythiophene: Luminescence enhancement induced by bile-acid anions

The water-soluble poly{trimethyl-[7-(3-thienylsulfanyl)heptyl]ammonium iodide-co-thiophene} (PTN⁺Me₃) forms aggregates whose size span a large range of values, depending on solvent, concentration and film formation conditions. Larger aggregates were detected by atomic force microscopy and dynamic light scattering, smaller ones by DOSY NMR, UV–visible and fluorescence. All techniques indicate a reduced aggregation of PTN⁺Me₃ in DMSO relative to water and a marked de-aggregation of PTN⁺Me₃ in water following addition of bile-acid anions such as deoxycholate and ursodeoxycholate. The latter effect shows itself through a very large enhancement of the polymer photoluminescence likely caused by disruption of aggregated non-emissive exciton traps. A tailored combination of electrostatic and hydrophobic interactions between the polymer and the bile-acid anions seems to be necessary to achieve this effect. These observations suggest that this polythiophene might provide a basis for the development of fluorescent sensors suitable for the detection of medium-sized amphiphilic biomolecules.     

Continuity of academic intrinsic motivation from childhood through late adolescence: A longitudinal study.

Two aspects of continuity, stability of individual differences and means, were examined in a longitudinal study from the middle elementary through the high school years. Two hypotheses regarding individual difference stability were supported with structural equation modeling in both the general-verbal and math domains: (a) Academic intrinsic motivation is a stable construct throughout these years, and (b) with advancement in age, academic intrinsic motivation becomes increasingly stable. A third hypothesis, that the mean level of academic intrinsic motivation declines over these ages, also was supported, and significant linear trends were obtained, but it was also found to be modified by particular subject areas, with math showing the greatest decline and social studies showing no significant change. The combination of these 2 aspects of continuity places those with low motivation early in their schooling particularly at risk. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A mass spectrometric investigation into microenvironmental effects in solid-supported radical chemistry

Deuterated N-ethylpiperidine hypophosphite (d-EPHP) and tributyltin deuteride (TBTD) have been used to explore potential microenvironmental effects in resin-bound radical propagation. A deuterium labelling mass spectrometric method was used to show that efficiency of radical chain propagation on resin can be influenced by the choice of solid-support when using the slow radical chain carrier, EPHP.     

Three Novel Bacteria Associated with Two Centric Diatom Species from the Mediterranean Sea,Thalassiosira rotula and Skeletonema marinoi

Diatoms are a successful group of microalgae at the base of the marine food web. For hundreds of millions of years, they have shared common habitats with bacteria, which favored the onset of interactions at different levels, potentially driving the synthesis of biologically active molecules. To unveil their presence, we sequenced the genomes of bacteria associated with the centric diatom Thalassiosira rotula from the Gulf of Naples. Annotation of the metagenome and its analysis allowed the reconstruction of three bacterial genomes that belong to currently undescribed species. Their investigation showed the existence of novel gene clusters coding for new polyketide molecules, antibiotics, antibiotic-resistance genes and an ectoine production pathway. Real-time PCR was used to investigate the association of these bacteria with three different diatom clones and revealed their preference for T. rotula FE80 and Skeletonema marinoi FE7, but not S. marinoi FE60 from the North Adriatic Sea. Additionally, we demonstrate that although all three bacteria could be detected in the culture supernatant (free-living), their number is up to 45 times higher in the cell associated fraction, suggesting a close association between these bacteria and their host. We demonstrate that axenic cultures of T. rotula are unable to grow in medium with low salinity (<28 ppt NaCl) whereas xenic cultures can tolerate up to 40 ppt NaCl with concomitant ectoine production, likely by the associated bacteria.     

Discontinuities and cognitive changes in an exposure-based cognitive therapy for depression.

Significant shifts or discontinuities in symptom course can mark points of transition and reveal important change processes. The authors investigated 2 patterns of change in depression-the rapid early response and a transient period of apparent worsening that the authors call a depression spike. Participants were 29 patients diagnosed with major depressive disorder who enrolled in an open trial of an exposure-based cognitive therapy. Hierarchical linear modeling revealed an overall cubic shape of symptom change and that both the rapid response and spike patterns predicted lower posttreatment depression. Patients wrote weekly narratives about their depression. Early narratives of rapid responders were coded as having more hope than those of nonrapid responders. The narratives of patients with a depression spike had more cognitive-emotional processing during this period of arousal than those without a spike. Findings are discussed in the context of cognitive-emotional processing theories in depression and anxiety disorders. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of visual complexity and sex of infant in the conjugate reinforcement paradigm.

For each of 2 sex-balanced groups of 3.5-mo-old infants (N = 24), illumination of a black and white slide with either a 2 * 2 or a 24 * 24 checkerboard pattern was made directly proportional to the momentary rate of nonnutritive sucks greater than a predetermined criterion. A noncontingent baseline period of responding was followed by several minutes of conjugate sucking. Sucking performance was assessed by (a) the number of minutes to reach the decrement criterion (satiation time), (b) the rate of criterion sucking, and (c) the proportion of sucks which exceeded the amplitude criterion. Results indicate that check density did not differentially affect the sucking performance on any of the measures; sex of the S was significantly related to performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fourier transform infrared microscopic imaging: effects of estrogen and estrogen deficiency on fracture healing in rat femurs

Infrared spectroscopic imaging with 6-10 microm spatial resolution was used to characterize the changes in fracture callus mineral content, carbonate content, mineral crystallinity, and collagen maturity in femurs of 3-month-old ovariectomized rats treated with estrogen (estrogen sufficiency) or vehicle (estrogen deficiency). Comparisons were also made in these animals to cortical bone at a distance from the callus. Analyses at 4, 8, and 12 weeks post fracture demonstrated that healing was accelerated in the estrogen-sufficient animals as demonstrated by increasing mineral content and collagen maturity and decreasing carbonate incorporation.