2,968 research outputs found
All-inorganic core-shell silica-titania mesoporous colloidal nanoparticles showing orthogonal functionality
Colloidal mesoporous silica (CMS) nanoparticles with a thin titania-enriched outer shell showing a spatially resolved functionality were synthesized by a delayed co-condensation approach. The titaniashell can serve as a selective nucleation site for the growth of nanocrystalline anatase clusters. These fully inorganic pure silica-core titania-enriched shell mesoporous nanoparticles show orthogonal functionality, demonstrated through the selective adsorption of a carboxylate-containing ruthenium N3-dye. UV-Vis and fluorescence spectroscopy indicate the strong interaction of the N3-dye with the titania-phase at the outer shell of the CMS nanoparticles. In particular, this interaction and thus the selective functionalization are greatly enhanced when anatase nanocrystallites are nucleated at the titania-enriched shell surface
The complexity of mesoporous silica nanomaterials unravelled by single molecule microscopy
Mesoporous silica nanomaterials are a novel class of materials that offer a highly complex porous network with nanometre-sized channels into which a wide amount of differently sized guests can be incorporated.
This makes them an ideal host for various applications for example in catalysis, chromatography and nanomedicine. For these applications, analyzing the host properties and understanding the complicated host–guest interactions is of pivotal importance. In this perspective we review some of our recent work that demonstrates that single molecule microscopy techniques can be utilized to characterize the porous silica host with unprecedented detail. Furthermore, the single molecule studies reveal sample heterogeneities and are a highly efficient tool to gain direct mechanistic insights into the host–guest interactions. Single molecule microscopy thus contributes to a thorough understanding of these nanomaterials enabling the development of novel tailor-made materials and hence optimizing their applicability significantly
Beyond the “Pain Matrix,†inter-run synchronization during mechanical nociceptive stimulation
Pain is a complex experience that is thought to emerge from the activity of multiple brain areas, some of which are inconsistently detected using traditional fMRI analysis. One hypothesis is that the traditional analysis of pain-related cerebral responses, by relying on the correlation of a predictor and the canonical hemodynamic response function (HRF)- the general linear model (GLM)- may under-detect the activity of those areas involved in stimulus processing that do not present a canonical HRF. In this study, we employed an innovative data-driven processing approach- an inter-run synchronization (IRS) analysis- that has the advantage of not establishing any pre-determined predictor definition. With this method we were able to evidence the involvement of several brain regions that are not usually found when using predictor-based analysis. These areas are synchronized during the administration of mechanical punctate stimuli and are characterized by a BOLD response different from the canonical HRF. This finding opens to new approaches in the study of pain imaging
Structured Perovskite-Based Catalysts and Their Application as Three-Way Catalytic Converters—A Review
Automotive Three-Way Catalysts (TWC) were introduced more than 40 years ago. Despite that, the development of a sustainable TWC still remains a critical research topic owing to the increasingly stringent emission regulations together with the price and scarcity of precious metals. Among other material classes, perovskite-type oxides are known to be valuable alternatives to conventionally used TWC compositions and have demonstrated to be suitable for a wide range of automotive applications, ranging from TWC to Diesel Oxidation Catalysts (DOC), from NOx Storage Reduction catalysts (NSR) to soot combustion catalysts. The interest in these catalysts has been revitalized in the past ten years by the introduction of the concept of catalyst regenerability of perovskite-based TWC, which is in principle well applicable to other catalytic processes as well, and by the possibility to reduce the amounts of critical elements, such as precious metals without seriously lowering the catalytic performance. The aim of this review is to show that perovskite-type oxides have the potential to fulfil the requirements (high activity, stability, and possibility to be included into structured catalysts) for implementation in TWC
Autism Spectrum Disorder Diagnosis Using Sparse Graph Embedding of Morphological Brain Networks
Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder involving a complex cognitive impairment that can be difficult to diagnose early enough. Much work has therefore been done investigating the use of machine-learning techniques on functional and structural connectivity networks for ASD diagnosis. However, networks based on the morphology of the brain have yet to be similarly investigated, despite research findings that morphological features, such as cortical thickness, are affected by ASD. In this paper, we first propose modelling morphological brain connectivity (or graph) using a set of cortical attributes, each encoding a unique aspect of cortical morphology. However, it can be difficult to capture for each subject the complex pattern of relationships between morphological brain graphs, where each may be affected simultaneously or independently by ASD. In order to solve this problem, we therefore also propose the use of high-order networks which can better capture these relationships. Further, since ASD and normal control (NC) high-dimensional connectomic data might lie in different manifolds, we aim to find a low-dimensional representation of the data which captures the intrinsic dimensions of the underlying connectomic manifolds, thereby allowing better learning by linear classifiers. Hence, we propose the use of sparse graph embedding (SGE) method, which allows us to distinguish between data points drawn from different manifolds, even when they are too close to one another. SGE learns a similarity matrix of the connectomic data graph, which then is used to embed the high-dimensional connectomic features into a low-dimensional space that preserves the locality of the original data. Our ASD/NC classification results outperformed several state-of-the-art methods including statistical feature selection, and local linear embedding methods
Risk factors for recurrence in patients with Clostridium difficile infection due to 027 and non-027 ribotypes
Objectives: Our objective was to evaluate factors associated with recurrence in patients with 027+ and 027– Clostridium difficile infection (CDI). Methods: Patients with CDI observed between January and December 2014 in six hospitals were consecutively included in the study. The 027 ribotype was deduced by the presence of tcdB, tcdB, cdt genes and the deletion Δ117 in tcdC (Xpert® C. difficile/Epi). Recurrence was defined as a positive laboratory test result for C. difficile more than 14 days but within 8 weeks after the initial diagnosis date with reappearance of symptoms. To identify factors associated with recurrence in 027+ and 027– CDI, a multivariate analysis was performed in each patient group. Subdistributional hazard ratios (sHRs) and 95% confidence intervals (95%CIs) were calculated. Results: Overall, 238 patients with 027+ CDI and 267 with 027– CDI were analysed. On multivariate analysis metronidazole monotherapy (sHR 2.380, 95%CI 1.549–3.60, p <0.001) and immunosuppressive treatment (sHR 3.116, 95%CI 1.906–5.090, p <0.001) were factors associated with recurrence in patients with 027+ CDI. In this patient group, metronidazole monotherapy was independently associated with recurrence in both mild/moderate (sHR 1.894, 95%CI 1.051–3.410, p 0.033) and severe CDI (sHR 2.476, 95%CI 1.281–4.790, p 0.007). Conversely, non-severe disease (sHR 3.704, 95%CI 1.437–9.524, p 0.007) and absence of chronic renal failure (sHR 16.129, 95%CI 2.155–125.000, p 0.007) were associated with recurrence in 027– CDI. Conclusions: Compared to vancomycin, metronidazole monotherapy appears less effective in curing CDI without relapse in the 027+ patient group, independently of disease severity
Glycopeptide resistance among coagulase- negative staphylococci that cause bacteremia: epidemiological and clinical findings from a case-control study
A 1-year prospective case-control study (ratio of control patients to case patients, 3:1) was performed to assess
the incidence, risk factors, and genotypic patterns of bacteremia caused by glycopeptide-resistant coagulasenegative
staphylococci (CoNS) and their correlation with hospital glycopeptide use. Among 535 subjects with
CoNS bacteremia, 20 subjects had a glycopeptide-resistant strain (19 strains were resistant to teicoplanin and
1 was resistant to both teicoplanin and vancomycin). The percentage of resistant isolates recovered in 1 year
was 8% in intensive care units and 3% and 2% in medical and surgical wards, respectively. Genotypic analysis
of resistant strains showed different patterns with a high degree of polymorphism. Use of glycopeptides in
individual wards was not statistically associated with the percentage of resistance. Previous exposure to β-lactams
and glycopeptides, multiple hospitalization in the previous year, and concomitant pneumonia were
significantly associated with the onset of glycopeptide-resistant CoNS bacteremia. Mortality rates were 25%
among case patients and 18% among control patients, and they were significantly higher among patients who
presented with concomitant pneumonia and a high Acute Physiology and Chronic Health Evaluation III score
Rehabilitation of Communicative Abilities in Patients with a History of TBI: Behavioral Improvements and Cerebral Changes in Resting-State Activity
A targeted training program for the rehabilitation of communicative abilities—Cognitive Pragmatic Treatment (CPT)—has been developed and previously tested on a sample of patients with traumatic brain injury (TBI), whose performance was found to have improved. Since cortical plasticity has been recognized as the main mechanism of functional recovery, we investigated whether and how behavioral improvements following the training program are accompanied by brain modifications. Eight TBI patients took part in the training program and were behaviorally assessed pre- and post-treatment; six of these patients were also evaluated with pre- and post-treatment resting state (rs) functional magnetic resonance imaging (fMRI). At the end of the rehabilitation program patients showed improvement in overall communicative performance, in both comprehension and production tasks. A follow-up retest revealed the stability of these results 3 months after completing the training program. At the brain level, we found significant increases in the amplitude of low frequency fluctuation (ALFF) index in the bilateral precentral gyrus, in the right middle and superior temporal gyri, in the right cingulate gyrus, and in the left inferior parietal lobule. We discuss these differences of brain activity in terms of their possible contribution to promoting recovery
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