214 research outputs found

    Surface modification and characterization of photon-upconverting nanoparticles for bioanalytical applications

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    Photon-upconverting nanoparticles (UCNPs) can be excited by near-infrared light and emit visible light (anti-Stokes emission) which prevents autofluorescence and light scattering of biological samples. The potential for background-free imaging has attracted wide interest in UCNPs in recent years. Small and homogeneous lanthanide-doped UCNPs that display high upconversion efficiency have typically been synthesized in organic solvents. Bioanalytical applications, however, require a subsequent phase transfer to aqueous solutions. Hence, the surface properties of UCNPs must be well designed and characterized to grant both a stable aqueous colloidal dispersion and the ability to conjugate biomolecules and other ligands on the nanoparticle surface. In this review, we introduce various routes for the surface modification of UCNPs and critically discuss their advantages and disadvantages. The last part covers various analytical methods that enable a thorough examination of the progress and success of the surface functionalization

    Extended surfaces modulate and can catalyze hydrophobic effects

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    Interfaces are a most common motif in complex systems. To understand how the presence of interfaces affect hydrophobic phenomena, we use molecular simulations and theory to study hydration of solutes at interfaces. The solutes range in size from sub-nanometer to a few nanometers. The interfaces are self-assembled monolayers with a range of chemistries, from hydrophilic to hydrophobic. We show that the driving force for assembly in the vicinity of a hydrophobic surface is weaker than that in bulk water, and decreases with increasing temperature, in contrast to that in the bulk. We explain these distinct features in terms of an interplay between interfacial fluctuations and excluded volume effects---the physics encoded in Lum-Chandler-Weeks theory [J. Phys. Chem. B 103, 4570--4577 (1999)]. Our results suggest a catalytic role for hydrophobic interfaces in the unfolding of proteins, for example, in the interior of chaperonins and in amyloid formation.Comment: 22 pages, 5 figure

    Novel Protocol for the Chemical Synthesis of Crustacean Hyperglycemic Hormone Analogues — An Efficient Experimental Tool for Studying Their Functions

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    The crustacean Hyperglycemic Hormone (cHH) is present in many decapods in different isoforms, whose specific biological functions are still poorly understood. Here we report on the first chemical synthesis of three distinct isoforms of the cHH of Astacus leptodactylus carried out by solid phase peptide synthesis coupled to native chemical ligation. The synthetic 72 amino acid long peptide amides, containing L- or D-Phe3 and (Glp1, D-Phe3) were tested for their biological activity by means of homologous in vivo bioassays. The hyperglycemic activity of the D-isoforms was significantly higher than that of the L-isoform, while the presence of the N-terminal Glp residue had no influence on the peptide activity. The results show that the presence of D-Phe3 modifies the cHH functionality, contributing to the diversification of the hormone pool

    The limited prosocial effects of meditation: A systematic review and meta-analysis

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    Many individuals believe that meditation has the capacity to not only alleviate mental-illness but to improve prosociality. This article systematically reviewed and meta-analysed the effects of meditation interventions on prosociality in randomized controlled trials of healthy adults. Five types of social behaviours were identified: compassion, empathy, aggression, connectedness and prejudice. Although we found a moderate increase in prosociality following meditation, further analysis indicated that this effect was qualified by two factors: type of prosociality and methodological quality. Meditation interventions had an effect on compassion and empathy, but not on aggression, connectedness or prejudice. We further found that compassion levels only increased under two conditions: when the teacher in the meditation intervention was a co-author in the published study; and when the study employed a passive (waiting list) control group but not an active one. Contrary to popular beliefs that meditation will lead to prosocial changes, the results of this meta-analysis showed that the effects of meditation on prosociality were qualified by the type of prosociality and methodological quality of the study. We conclude by highlighting a number of biases and theoretical problems that need addressing to improve quality of research in this area

    Framework and baseline examination of the German National Cohort (NAKO)

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    The German National Cohort (NAKO) is a multidisciplinary, population-based prospective cohort study that aims to investigate the causes of widespread diseases, identify risk factors and improve early detection and prevention of disease. Specifically, NAKO is designed to identify novel and better characterize established risk and protection factors for the development of cardiovascular diseases, cancer, diabetes, neurodegenerative and psychiatric diseases, musculoskeletal diseases, respiratory and infectious diseases in a random sample of the general population. Between 2014 and 2019, a total of 205,415 men and women aged 19–74 years were recruited and examined in 18 study centres in Germany. The baseline assessment included a face-to-face interview, self-administered questionnaires and a wide range of biomedical examinations. Biomaterials were collected from all participants including serum, EDTA plasma, buffy coats, RNA and erythrocytes, urine, saliva, nasal swabs and stool. In 56,971 participants, an intensified examination programme was implemented. Whole-body 3T magnetic resonance imaging was performed in 30,861 participants on dedicated scanners. NAKO collects follow-up information on incident diseases through a combination of active follow-up using self-report via written questionnaires at 2–3 year intervals and passive follow-up via record linkages. All study participants are invited for re-examinations at the study centres in 4–5 year intervals. Thereby, longitudinal information on changes in risk factor profiles and in vascular, cardiac, metabolic, neurocognitive, pulmonary and sensory function is collected. NAKO is a major resource for population-based epidemiology to identify new and tailored strategies for early detection, prediction, prevention and treatment of major diseases for the next 30 years. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10654-022-00890-5

    Grammatical gender and linguistic relativity: A systematic review

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    Many languages assign nouns to a grammatical gender class, such that ‘bed’ might be assigned masculine gender in one language (e.g. Italian) but feminine gender in another (e.g. Spanish). In the context of research assessing the potential for language to influence thought (the linguistic relativity hypothesis), a number of scholars have investigated whether grammatical gender assignment ‘rubs off’ on concepts themselves, such that Italian speakers might conceptualise beds as more masculine than Spanish speakers. We systematically reviewed 43 pieces of empirical research examining grammatical gender and thought, which together tested 5,895 participants. We classified the findings in terms of their support for this hypothesis, and assessed the results against parameters previously identified as potentially influencing outcomes. Overall, we found that support was strongly task- and context-dependent, and rested heavily on outcomes that have clear and equally-viable alternative explanations. We also argue that it remains unclear whether grammatical gender is in fact a useful tool for investigating relativity
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