Spatially correlated fluorescence/AFM of individual nanosized particles and biomolecules

Individual fluorescent polystyrene nanospheres (<10-100-nm diameter) and individual fluorescently labeled DNA molecules were dispersed on mica and analyzed using time-resolved fluorescence spectroscopy and atomic force microscopy (AFM). Spatial correlation of the fluorescence and AFM measurements was accomplished by (1) positioning a single fluorescent particle into the near diffraction-limited confocal excitation region of the optical microscope, (2) recording the time-resolved fluorescence emission, and (3) measuring the intensity of the excitation laser light scattered from the apex of an AFM probe tip and the AFM topography as a function of the lateral position of the tip relative to the sample substrate. The latter measurements resulted in concurrent high-resolution (approximately 10-20 nm laterally) images of the laser excitation profile of the confocal microscope and the topography of the sample. Superposition of these optical and topographical images enabled unambiguous identification of the sample topography residing within the excitation region of the optical microscope, facilitating the identification and structural characterization of the nanoparticle(s) or biomolecule(s) responsible for the fluorescence signal observed in step 2. These measurements also provided the lateral position of the particles relative to the laser excitation profile and the surrounding topography with nanometer-scale precision and the relationship between the spectroscopic and structural properties of the particles. Extension of these methods to the study of other types of nanostructured materials is discussed.     

Fighting the Huntington’s Disease with a G-Quadruplex-Forming Aptamer Specifically Binding to Mutant Huntingtin Protein: Biophysical Characterization,In Vitro and In Vivo Studies

A set of guanine-rich aptamers able to preferentially recognize full-length huntingtin with an expanded polyglutamine tract has been recently identified, showing high efficacy in modulating the functions of the mutated protein in a variety of cell experiments. We here report a detailed biophysical characterization of the best aptamer in the series, named MS3, proved to adopt a stable, parallel G-quadruplex structure and show high nuclease resistance in serum. Confocal microscopy experiments on HeLa and SH-SY5Y cells, as models of non-neuronal and neuronal cells, respectively, showed a rapid, dose-dependent uptake of fluorescein-labelled MS3, demonstrating its effective internalization, even in the absence of transfecting agents, with no general cytotoxicity. Then, using a well-established Drosophila melanogaster model for Huntington’s disease, which expresses the mutated form of human huntingtin, a significant improvement in the motor neuronal function in flies fed with MS3 was observed, proving the in vivo efficacy of this aptamer.     

Truncated Analogues of a G-Quadruplex-Forming Aptamer Targeting Mutant Huntingtin: Shorter Is Better!

Two analogues of the MS3 aptamer, which was previously shown to have an exquisite capability to selectively bind and modulate the activity of mutant huntingtin (mHTT), have been here designed and evaluated in their physicochemical and biological properties. Featured by a distinctive propensity to form complex G-quadruplex structures, including large multimeric aggregates, the original 36-mer MS3 has been truncated to give a 33-mer (here named MS3-33) and a 17-mer (here named MS3-17). A combined use of different techniques (UV, CD, DSC, gel electrophoresis) allowed a detailed physicochemical characterization of these novel G-quadruplex-forming aptamers, tested in vitro on SH-SY5Y cells and in vivo on a Drosophila Huntington’s disease model, in which these shorter MS3-derived oligonucleotides proved to have improved bioactivity in comparison with the parent aptamer.     

Sensing pulsed light by means of Multi-Walled Carbon Nanotubes

We report first results on a prototype radiation detector made of multi-walled carbon nanotubes grown on a sapphire substrate. Signals induced in nanotubes by a pulsed laser beam have been collected and analyzed. The optical and electrical inactivity of the substrate material highlights the role of nanotubes.     

Generating quality open content: A functional group perspective based on the time, interaction, and performance theory

We applied the input-process-output approach and time, interaction, and performance theory to examine the input factors (organisational, group-related, and individual) and process factors (group production, group well-being, and member support) that yield group effectiveness, measured as high-quality articles in Wikipedia. The results provided evidence of the positive effects of: group size and shared experience on both group process variables and group effectiveness; group heterogeneity on group production; organisational support and member activeness on group well-being; member activeness on member support; and organisational support and member activeness on group effectiveness.     

Myelodysplasia in triplet pregnancy

INTRODUCTION: The myelodysplastic syndromes (MSD) are a group of hematologic disorders that manifest dysplastic hematopoiesis and usually a hypercellular bone marrow. Ineffective hematopoiesis leads to haematologic failure in these syndromes. The MDS are a rare event during pregnancy although the exact incidence is unknown it is likely to be less than that for leukaemia. CLINICAL REPORT: The case, a 29 year old woman, presented during 23rd week of her first, triplet, pregnancy with symptoms of anemia and thrombocytopenia is described. DISCUSSION: The pathogenetic aspect and diagnostic management is discussed, underlined especially under the point of view of the triplet pregnancy. It is suggested that the association of myelodysplastic syndromes during pregnancy is coincidental and that acute leukemia evolves in a majority of these cases. Furthermore, refractory macrocytic anemias in pregnancy need to be carefully evaluated for a primary myelodysplastic state.     

Soldering of mild steels: functional joints

In recent years, adhesive joints have replaced numerous soldered joints, especially in applications where electrical conductivity is not required from the members of the joint. Nevertheless, soldered joints are still used in applications ranging from electronics to high-technology components. The present work seeks to demonstrate that soldered joints, which can be considered as functional joints, have very good mechanical properties and can provide more than acceptable levels of leak tightness. Hence, microstructural characterisation studies have been carried out on the filler metals used to solder mild steel, the surface preparation required to achieve the best final properties has been assessed, the joints characterised by means of radiography and the mechanical properties of the joints determined. The results obtained for soldered joints have been compared with those obtained from adhesive and hybrid joints.

Finally, scanning electron microscopy has been performed on the fracture surfaces of the soldered joint.     

Effects of winter housing systems on production,economics, body weight,body condition score,and bedding cultures for organic dairy cows

Certified-organic dairy cows (n = 268) were used to evaluate the effect of 2 winter (December to April) housing systems on milk production, somatic cell score (SCS), body weight, body condition score (BCS), and economics across 3 winter seasons (2013, 2014, and 2015). Bedding cultures from the housing systems were also evaluated. Cows were randomly assigned to 2 treatments (2 replicates per group): (1) outdoor (straw pack, n = 140) or (2) indoor (3-sided compost bedded pack barn, n = 128). Cows calved during 2 seasons (spring or fall) at the University of Minnesota West Central Research and Outreach Center, Morris, Minnesota, organic dairy. Milk, fat, and protein production and SCS were recorded from monthly milk recording. Body weight and BCS were recorded biweekly as cows exited the milking parlor. Bedding cultures from the housing systems were collected biweekly. Costs for key inputs and the price received for milk production were recorded for the study period and averaged for use in the profitability analysis. Energy-corrected milk and SCS were not different for the outdoor (15.1 kg/d, 2.64) and indoor (15.7 kg/d, 2.57) housing systems, respectively. In addition, cows in the outdoor and indoor housing systems were not different for body weight (528 vs. 534 kg) and BCS (3.22 vs. 3.23), respectively. Daily dry matter intake was 19.1 kg/d for the outdoor cows and 19.6 kg/d for indoor cows. The total bacteria count from bedding samples tended to be lower in the outdoor (13.0 log₁₀ cfu/mL) compared with the indoor (14.9 log₁₀ cfu/mL) system. Milk revenue and feed cost were not different for the 2 housing systems. Labor and bedding costs were lower and net return was higher for the outdoor housing system. The outdoor straw pack system had a $1.42/cow per day net return advantage over the indoor compost bedded pack barn. In summary, lactating cows housed outdoors on straw-bedded packs did not differ for production or SCS, or for body weight, BCS, or dry matter intake, but had greater profitability than cows housed in an indoor compost bedded pack barn.     

A Shortcut Method for the Estimation of Structured Packings HEPT in Distillation

A shortcut method to calculate HETP for metal structured packings is proposed. The method is a simplification and extension of Lockett's equation for sheet packings, based on the Bravo, Rocha and Fair model. It is applicable at vacuum or pressure distillation of organic or aqueous mixtures in columns of sheet and gauze packings. The necessary variables are specific surface of packing, density of vapor and liquid and flow (when gauze packings are being considered). No estimation of hydrodynamic conditions is necessary.     

What makes a good contributor? Understanding contributor behavior within large Free/Open Source Software projects – A socialization perspective

Attracting new contributors is a necessary but not a sufficient condition, to ensure the survival and long-term success of Free/Open Source Software (FOSS) projects. The well-being of a FOSS project depends on the turning of project newcomers into ‘good contributors’ that is to say into individuals that substantially contribute to the project - but also that perform citizenship behaviors that protect and nurture its community. This study is a mixed-methods investigation of the socialization factors that influence contributor performance in large FOSS projects. A qualitative research component resulted into the development of a FOSS socialization framework as well as into the identification of key FOSS project citizenship behaviors. A conceptual model was then developed and empirically examined with 367 contributors from 12 large FOSS projects. The model hypothesizes the mediating effect of two proximal socialization variables, social identification and social integration, between FOSS newcomer socialization factors and contributor performance (conceptualized as task performance and community citizenship behaviors). The results demonstrate the influence of social identification and social integration in predicting contributor performance, as well as the importance of key socialization factors that are: task segregation, task purposefulness, interaction intensity, and supportiveness. Theoretical and practical implications are discussed.