Quenching of chlorophyll fluorescence induced by silver nanoparticles

The interaction between chlorophyll (Chl) and silver nanoparticles (AgNPs) was evaluated by analyzing the optical behavior of Chl molecules surrounded by different concentrations of AgNPs (10, 60, and 100 nm of diameter). UV–Vis absorption, steady state and time-resolved fluorescence measurements were performed for Chl in the presence and absence of these nanoparticles. AgNPs strongly suppressed the Chl fluorescence intensity at 678 nm. The Stern-Volmer constant (KSV) showed that fluorescence suppression is driven by the dynamic quenching process. In particular, KSV was nanoparticle size-dependent with an exponential decrease as a function of the nanoparticle diameter. Finally, changes in the Chl fluorescence lifetime in the presence of nanoparticles demonstrated that the fluorescence quenching may be induced by the excited electron transfer from the Chl molecules to the metal nanoparticles

Human resource allocation management in multiple projects using sociometric techniques

This article describes a new application of key psychological concepts in the area of Sociometry for the selection of workers within organizations in which projects are developed. The project manager can use a new procedure to determine which individuals should be chosen from a given pool of resources and how to combine them into one or several simultaneous groups/projects in order to assure the highest possible overall work efficiency from the standpoint of social interaction. The optimization process was carried out by means of matrix calculations performed using a computer or even manually, and based on a number of new ratios generated ad-hoc and composed on the basis of indices frequently used in Sociometry

An Analysis of the Role of the Indigenous Microbiota in Cholesterol Gallstone Pathogenesis

Background and Aims: Cholesterol gallstone disease is a complex process involving both genetic and environmental variables. No information exists regarding what role if any the indigenous gastrointestinal microbiota may play in cholesterol gallstone pathogenesis and whether variations in the microbiota can alter cholesterol gallstone prevalence rates. Methods: Genetically related substrains (BALB/cJ and BALB/cJBomTac) and (BALB/AnNTac and BALB/cByJ) of mice obtained from different vendors were compared for cholesterol gallstone prevalence after being fed a lithogenic diet for 8 weeks. The indigenous microbiome was altered in these substrains by oral gavage of fecal slurries as adults, by cross-fostering to mice with divergent flora at <1day of age or by rederiving into a germ-free state. Results: Alterations in the indigenous microbiome altered significantly the accumulation of mucin gel and normalized gallbladder weight but did not alter cholesterol gallstone susceptibility in conventionally housed SPF mice. Germ-free rederivation rendered mice more susceptible to cholesterol gallstone formation. This susceptibility appeared to be largely due to alterations in gallbladder size and gallbladder wall inflammation. Colonization of germ-free mice with members of altered Schaedler flora normalized the gallstone phenotype to a level similar to conventionally housed mice. Conclusions: These data demonstrate that alterations in the gastrointestinal microbiome may alter aspects of cholesterol gallstone pathogenesis and that in the appropriate circumstances these changes may impact cholesterol cholelithogenesis.National Institutes of Health (U.S.) (Grant T32OD010978)National Institutes of Health (U.S.) (Grant P30ES002109)National Institutes of Health (U.S.) (Grant R01AT004326

Cooperativity among Short Amyloid Stretches in Long Amyloidogenic Sequences

Amyloid fibrillar aggregates of polypeptides are associated with many neurodegenerative diseases. Short peptide segments in protein sequences may trigger aggregation. Identifying these stretches and examining their behavior in longer protein segments is critical for understanding these diseases and obtaining potential therapies. In this study, we combined machine learning and structure-based energy evaluation to examine and predict amyloidogenic segments. Our feature selection method discovered that windows consisting of long amino acid segments of ∼30 residues, instead of the commonly used short hexapeptides, provided the highest accuracy. Weighted contributions of an amino acid at each position in a 27 residue window revealed three cooperative regions of short stretch, resemble the β-strand-turn-β-strand motif in A-βpeptide amyloid and β-solenoid structure of HET-s(218–289) prion (C). Using an in-house energy evaluation algorithm, the interaction energy between two short stretches in long segment is computed and incorporated as an additional feature. The algorithm successfully predicted and classified amyloid segments with an overall accuracy of 75%. Our study revealed that genome-wide amyloid segments are not only dependent on short high propensity stretches, but also on nearby residues

Evidence of phytotoxicity and genotoxicity in Hordeum vulgare L. exposed to CeO2 and TiO2 nanoparticles.

Engineered nanoscale materials (ENMs) are considered emerging contaminants since they are perceived as a potential threat to the environment and the human health. The reactions of living organisms when exposed to metal nanoparticles (NPs) or NPs of different size are not well known. Very few studies on NPs–plant interactions have been published, so far. For this reason there is also great concern regarding the potential NPs impact to food safety. Early genotoxic and phytotoxic effects of cerium oxide NPs (nCeO(2)) and titanium dioxide NPs (nTiO(2)) were investigated in seedlings of Hordeum vulgare L. Caryopses were exposed to an aqueous dispersion of nCeO(2) and nTiO(2) at, respectively 0, 500, 1000, and 2000 mg l(-1) for 7 days. Genotoxicity was studied by Randomly Amplified Polymorphism DNA (RAPDs) and mitotic index on root tip cells. Differences between treated and control plants were observed in RAPD banding patterns as well as at the chromosomal level with a reduction of cell divisions. At cellular level we monitored the oxidative stress of treated plants in terms of reactive oxygen species (ROS) generation and ATP content. Again nCeO(2) influenced clearly these two physiological parameters, while nTiO(2) were ineffective. In particular, the dose 500 mg l(-1) showed the highest increase regarding both ROS generation and ATP content; the phenomenon were detectable, at different extent, both at root and shoot level. Total Ce and Ti concentration in seedlings was detected by ICP-OES. TEM EDSX microanalysis demonstrated the presence of aggregates of nCeO(2) and nTiO(2) within root cells of barley. nCeO(2) induced modifications in the chromatin aggregation mode in the nuclei of both root and shoot cells

The impacts of increased heat stress events on wheat yield under climate change in China

China is the largest wheat producing country in the world. Wheat is one of the two major staple cereals consumed in the country and about 60% of Chinese population eats the grain daily. To safeguard the production of this important crop, about 85% of wheat areas in the country are under irrigation or high rainfall conditions. However, wheat production in the future will be challenged by the increasing occurrence and magnitude of adverse and extreme weather events. In this paper, we present an analysis that combines outputs from a wide range of General Circulation Models (GCMs) with observational data to produce more detailed projections of local climate suitable for assessing the impact of increasing heat stress events on wheat yield. We run the assessment at 36 representative sites in China using the crop growth model CSM-CropSim Wheat of DSSAT 4.5. The simulations based on historical data show that this model is suitable for quantifying yield damages caused by heat stress. In comparison with the observations of baseline 1996-2005, our simulations for the future indicate that by 2100, the projected increases in heat stress would lead to an ensemble-mean yield reduction of –7.1% (with a probability of 80%) and –17.5% (with a probability of 96%) for winter wheat and spring wheat, respectively, under the irrigated condition. Although such losses can be fully compensated by CO2 fertilization effect as parameterized in DSSAT 4.5, a great caution is needed in interpreting this fertilization effect because existing crop dynamic models are unable to incorporate the effect of CO2 acclimation (the growth enhancing effect decreases over time) and other offsetting forces

The Relative Influence of Competition and Prey Defenses on the Phenotypic Structure of Insectivorous Bat Ensembles in Southern Africa

Deterministic filters such as competition and prey defences should have a strong influence on the community structure of animals such as insectivorous bats that have life histories characterized by low fecundity, low predation risk, long life expectancy, and stable populations. We investigated the relative influence of these two deterministic filters on the phenotypic structure of insectivorous bat ensembles in southern Africa. We used null models to simulate the random phenotypic patterns expected in the absence of competition or prey defences and analysed the deviations of the observed phenotypic pattern from these expected random patterns. The phenotypic structure at local scales exhibited non-random patterns consistent with both competition and prey defense hypotheses. There was evidence that competition influenced body size distribution across ensembles. Competition also influenced wing and echolocation patterns in ensembles and in functional foraging groups with high species richness or abundance. At the same time, prey defense filters influenced echolocation patterns in two species-poor ensembles. Non-random patterns remained evident even after we removed the influence of body size from wing morphology and echolocation parameters taking phylogeny into account. However, abiotic filters such as geographic distribution ranges of small and large-bodied species, extinction risk, and the physics of flight and sound probably also interacted with biotic filters at local and/or regional scales to influence the community structure of sympatric bats in southern Africa. Future studies should investigate alternative parameters that define bat community structure such as diet and abundance to better determine the influence of competition and prey defences on the structure of insectivorous bat ensembles in southern Africa

Comparison between the disease-specific Airways Questionnaire 20 and the generic 15D instruments in COPD

<p>Abstract</p> <p>Background</p> <p>Given that the assessment of health-related quality of life (HRQoL) is an essential outcome measure to optimize chronic obstructive pulmonary disease (COPD) patient management, there is a need for a short and fast, reliable and valid instrument for routine use in clinical practice. The objective of this study was to analyse the relationship between the disease-specific Airways questionnaire (AQ20) and the generic 15D health-related quality of life (HRQoL) instrument simultaneously in a large cohort of patients with COPD. We also compare the HRQoL of COPD patients with that of the general population.</p> <p>Methods</p> <p>The AQ20 and 15D were administered to 739 COPD patients representing an unselected hospital-based COPD population. The completion rates and validity of, and correlations among the questions and dimension scores were examined. A factor analysis with varimax rotation was performed in order to find subsets of highly correlating items of the questionnaires.</p> <p>Results</p> <p>The summary scores of AQ20 and 15D were highly correlated (r = - 0.71, p < 0.01). In AQ20 over 50% of patients reported frequent cough, breathlessness during domestic work, and chest problem limiting their full enjoyment of life. 15D results showed a noteworthy decrease of HRQoL in breathing, mobility, sleeping, usual activities, discomfort and symptoms, vitality, and sexual activity (scores ≤ 0.75). Compared to the age- and gender-standardized Finnish general population, the COPD patients were statistically significantly worse off on 13 of 15 dimensions.</p> <p>Conclusions</p> <p>The AQ20 and 15D summary scores are comparable in terms of measuring HRQoL in COPD patients. The data support the validity of 15D to measure the quality of life in COPD. COPD compromises the HRQoL broadly, as reflected by the generic instrument. Both questionnaires are simple and short, and could easily be used in clinical practice with high completion rates.</p

Observation of associated near-side and away-side long-range correlations in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector

Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT