Exciton spin dynamics and photoluminescence polarization of CdSe/CdS dot-in-rod nanocrystals in high magnetic fields

The exciton spin dynamics and polarization properties of the related emission are investigated in colloidal CdSe/CdS dot-in-rod (DiR) and spherical core/shell nanocrystal (NC) ensembles by magneto-optical photoluminescence (PL) spectroscopy in magnetic fields up to 15 T. It is shown that the degree of circular polarization (DCP) of the exciton emission induced by the magnetic field is affected by the NC geometry as well as the exciton fine structure and can provide information on nanorod orientation. A theory to describe the circular and linear polarization properties of the NC emission in magnetic field is developed. It takes into account phonon mediated coupling between the exciton fine structure states as well as the dielectric enhancement effect resulting from the anisotropic shell of DiR NCs. This theoretical approach is used to model the experimental results and allows us to explain most of the measured features. The spin dynamics of the dark excitons is investigated in magnetic fields by time-resolved photoluminescence. The results highlight the importance of confined acoustic phonons in the spin relaxation of dark excitons. The bare core surface as well as the core/shell interface give rise to an efficient spin relaxation channel, while the surface of core/shell NCs seems to play only a minor role.Comment: 18 pages, 15 figure

Structural Transitions and Thermally Averaged Infrared Spectra of Small Methanol Clusters

Classical Monte Carlo and molecular dynamics (MD) simulations were carried out to investigate the structures, the infrared spectra, and the rigid-nonrigid transitions of small methanol clusters (CH3OH)n, n=3-6. The study was motivated by experimental results for these clusters from size specific infrared (IR) dissociation spectroscopy. The MD simulations revealed the following transitions: The trimer passes from a rigid ring configuration into a series of nonrigid open chain structures starting at 197 K. For n=4 and 5 such transitions occur between rings and rapidly fluctuating ring structures at T=357 and 243 K, respectively. For n=6 first a pure isomeric transition between the two energetically lowest isomers of S6 and C2 symmetry is found at 35 K, and then a similar transition to a nonrigid behavior as is observed for n=4 and 5 is seen at 197 K. The measured spectral display in all cases the rigid lowest energy configurations

Fuel effect on the liquid-phase penetration of an evaporating spray under transient diesel-like conditions

Measurements of the maximum liquid-phase penetration have been performed injecting five different fuels through a single-hole nozzle in an optical engine under a large set of thermodynamic and injection conditions. The focus of this paper is twofold. First, it intends to study fuel physical properties on liquid-phase fuel penetration. The choice made on Fischer-Tropsch diesel (FTD) and biodiesel fuels has been highly motivated by their potential to be, at short or middle term, possible substitutes to the conventional diesel fuel. Extensive characterization of fuel physical and chemical properties under ambient conditions are provided and related to the liquid-phase penetration in order to provide an accessible tool to predict liquid spray behavior based on cheap, off-engine measurements. Fischer-Tropsch fuels appeared to be the easiest to vaporize while biodiesel blends were getting always harder to vaporize as the Rapeseed Methyl Ester (RME) rate was increased. The second objective of this work is to study the time-response of liquid-phase penetration when subjected to density and temperature variations. Injections of 8 ms at three different pressures have been performed in transient diesel-like conditions with density and temperature time derivatives up to 2000 kg m -3 s -1 and 20,000 K s -1. In most cases, the spray appeared to closely follow predictions made from empirical models built out of steady-state ambient conditions, leading to the conclusion of an instantaneous adjustment of the spray to its environment, validating: (1) the hypothesis made in 1D spray models; (2) the use of empirical models in unsteady-state environment when obtained under steady-state conditions.The authors wish to acknowledge the Spanish Ministry of Education and Science for the financial support through the OPTICOMB project (TRA2007-67961-C03-01) and Jean-Guillaume Nerva's Grant (BES-2008-004420). The authors would also like to thank Daniel Lerida for the management of the facility and his assistance in data acquisition.Pastor Soriano, JV.; García Oliver, JM.; Nerva, J.; Giménez, B. (2011). Fuel effect on the liquid-phase penetration of an evaporating spray under transient diesel-like conditions. Fuel. 90(11):3369-3381. https://doi.org/10.1016/j.fuel.2011.05.006S33693381901

Enriching Visual with Verbal Explanations for Relational Concepts -- Combining LIME with Aleph

With the increasing number of deep learning applications, there is a growing demand for explanations. Visual explanations provide information about which parts of an image are relevant for a classifier's decision. However, highlighting of image parts (e.g., an eye) cannot capture the relevance of a specific feature value for a class (e.g., that the eye is wide open). Furthermore, highlighting cannot convey whether the classification depends on the mere presence of parts or on a specific spatial relation between them. Consequently, we present an approach that is capable of explaining a classifier's decision in terms of logic rules obtained by the Inductive Logic Programming system Aleph. The examples and the background knowledge needed for Aleph are based on the explanation generation method LIME. We demonstrate our approach with images of a blocksworld domain. First, we show that our approach is capable of identifying a single relation as important explanatory construct. Afterwards, we present the more complex relational concept of towers. Finally, we show how the generated relational rules can be explicitly related with the input image, resulting in richer explanations

Phosphorus bioavailability in soil profiles of a long-term fertilizer experiment: The evaluation of their bioaccessibility

Global agricultural productivity depends on the use of finite phosphorus (P) resources of which not only the topsoil, but also subsoil, can hold immense reserves. To assess potential soil contribution to plant nutrition, we compared the P status of Stagnic Cambisol profiles in experimental plots that received different P fertilizer applications (control, triple superphosphate (TSP), compost, compost+TSP) for 16 years. Sequential fractionation was combined with P K-edge X-ray absorption near edge structure (XANES) spectroscopy to identify the chemical P speciation. Fertilized topsoils (21 to 69 kg P ha-1 a-1) showed P reserves larger by a factor of 1.2 to 1.4, and subsoil P reserves larger by a factor of 1.3 to 1.5 than those of the control. P-XANES revealed the predominance of inorganic P species such as moderately labile Fe- (46 to 92%), Al- (0 to 40%), and Ca- (0 to 15%) P compounds besides organic P (0 to 13%) in all treatments. The fertilizer application slightly altered P speciation throughout the profiles, but the type of fertilizer had no significant effect on it. Optimal plant growth requirements are restricted by the exchangeable P from the solid phase within the soil solution. Therefore, ongoing research focuses on the accessibility of P from P loaded amorphous Fe- and Al-hydroxides, previously identified as the predominant abiotic P forms. To assess their P desorption potential, P-33 rhizotron experiments combined with P-33 isotopic exchange kinetics (IEK) are underway. Preliminary results indicated that besides differences in P binding capacity of soil hydroxides, physical soil parameters, such as the matric potential, strongly control soil P availability, thus plant P acquisition rates can vary among different soil types. Our results gained new detailed information about P bioavailability under agricultural practice. The investigations towards P bioaccessibility may contribute to improved interpretation of soil P tests and reduced fertilizer recommendations

N-Myc-induced metabolic rewiring creates novel therapeutic vulnerabilities in neuroblastoma

N-Myc is a transcription factor that is aberrantly expressed in many tumor types and is often correlated with poor patient prognosis. Recently, several lines of evidence pointed to the fact that oncogenic activation of Myc family proteins is concomitant with reprogramming of tumor cells to cope with an enhanced need for metabolites during cell growth. These adaptions are driven by the ability of Myc proteins to act as transcriptional amplifiers in a tissue-of-origin specific manner. Here, we describe the effects of N-Myc overexpression on metabolic reprogramming in neuroblastoma cells. Ectopic expression of N-Myc induced a glycolytic switch that was concomitant with enhanced sensitivity towards 2-deoxyglucose, an inhibitor of glycolysis. Moreover, global metabolic profiling revealed extensive alterations in the cellular metabolome resulting from overexpression of N-Myc. Limited supply with either of the two main carbon sources, glucose or glutamine, resulted in distinct shifts in steady-state metabolite levels and significant changes in glutathione metabolism. Interestingly, interference with glutamine-glutamate conversion preferentially blocked proliferation of N-Myc overexpressing cells, when glutamine levels were reduced. Thus, our study uncovered N-Myc induction and nutrient levels as important metabolic master switches in neuroblastoma cells and identified critical nodes that restrict tumor cell proliferation

Towards the development of a simulator for investigating the impact of people management practices on retail performance

               \ud           \ud 

Risk factors for advanced colorectal neoplasia and colorectal cancer detected at surveillance:a nationwide study in the modern era

Aim: Recommendations for surveillance after colonoscopy are based on risk factors for metachronous advanced colorectal neoplasia (AN) and colorectal cancer (CRC). The value of these risk factors remains unclear in populations enriched by individuals with a positive faecal immunochemical test and were investigated in a modern setting. Methods and Results: This population-based cohort study included all individuals in the Netherlands of ≥55 years old with a first adenoma diagnosis in 2015. A total of 22,471 patients were included. Data were retrieved from the Dutch Nationwide Pathology Databank (Palga). Primary outcomes were metachronous AN and CRC. Patient and polyp characteristics were evaluated by multivariable Cox regression analyses. During follow-up, 2416 (10.8%) patients were diagnosed with AN, of which 557 (2.5% from the total population) were CRC. Adenomas with high-grade dysplasia (hazard ratio [HR] 1.60, 95% confidence interval [CI] 1.40–1.83), villous histology (HR 1.91, 95% CI 1.59–2.28), size ≥10 mm (HR 1.12, 95% CI 1.02–1.23), proximal location (HR 1.12, 95% CI 1.02–1.23), two or more adenomas (HR 1.28, 95% CI 1.16–1.41), and serrated polyps ≥10 mm (HR 1.67, 95% CI 1.42–1.97) were independent risk factors for metachronous AN. In contrast, only adenomas with high-grade dysplasia (HR 2.49, 95% CI 1.92–3.24) were an independent risk factor for metachronous CRC. Conclusions: Risk factors for metachronous AN and CRC were identified for populations with access to a faecal immunochemical test (FIT)-based screening programme. If only risk factors for metachronous CRC are considered, a reduction in criteria for surveillance seems reasonable.</p

Discovering novel hydrolases from hot environments

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordNovel hydrolases from hot and other extreme environments showing appropriate performance and/or novel functionalities and new approaches for their systematic screening are of great interest for developing new processes, for improving safety, health and environment issues. Existing processes could benefit as well from their properties. The workflow, based on the HotZyme project, describes a multitude of technologies and their integration from discovery to application, providing new tools for discovering, identifying and characterizing more novel thermostable hydrolases with desired functions from hot terrestrial and marine environments. To this end, hot springs worldwide were mined, resulting in hundreds of environmental samples and thousands of enrichment cultures growing on polymeric substrates of industrial interest. Using high-throughput sequencing and bioinformatics, 15 hot spring metagenomes, as well as several sequenced isolate genomes and transcriptomes were obtained. To facilitate the discovery of novel hydrolases, the annotation platform Anastasia and a whole-cell bioreporter-based functional screening method were developed. Sequence-based screening and functional screening together resulted in about 100 potentially new hydrolases of which more than a dozen have been characterized comprehensively from a biochemical and structural perspective. The characterized hydrolases include thermostable carboxylesterases, enol lactonases, quorum sensing lactonases, gluconolactonases, epoxide hydrolases, and cellulases. Apart from these novel thermostable hydrolases, the project generated an enormous amount of samples and data, thereby allowing the future discovery of even more novel enzymes.European CommissionEuropean Union FP