Two-Dimensional Flow Nanometry of Biological Nanoparticles for Accurate Determination of Their Size and Emission Intensity

Biological nanoparticles (BNPs) are of high interest due to their key role in various biological processes and use as biomarkers. BNP size and molecular composition are decisive for their functions, but simultaneous determination of both properties with high accuracy remains challenging, which is a severe limitation. Surface-sensitive microscopy allows one to precisely determine fluorescence or scattering intensity, but not the size of individual BNPs. The latter is better determined by tracking their random motion in bulk, but the limited illumination volume for tracking this motion impedes reliable intensity determination. We here show that attaching BNPs (specifically, vesicles and functionalized gold NPs) to a supported lipid bilayer, subjecting them to a hydrodynamic flow, and tracking their motion via surface-sensitive imaging enable to determine their diffusion coefficients and flow-induced drift velocities and to accurately quantify both BNP size and emission intensity. For vesicles, the high accuracy is demonstrated by resolving the expected radius-squared dependence of their fluorescence intensity.Comment: 28 pages, 5 figure

Psychometric evaluation of the German version of a social support scale of FAFHES (family functioning, family health and social support)

This is the peer reviewed version which has been published in final form at https://doi.org/10.1111/scs.12700. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.BACKGROUND: Family members often need to be supported in informal care of the elderly and desire to be involved into care planning and decision-making. Valid and reliable instruments are needed to measure how family members perceive the care and support they receive from nurses for older family members living at home. AIM: The purpose of this study was to translate the 20-item social support scale of the Family Functioning, Family Health and Social Support (FAFHES) questionnaire from English to German and test the validity and reliability of the scale among Swiss-German-speaking family caregivers of home-dwelling elderly people who receive home healthcare services. METHODS: A cross-sectional study was conducted to test the empirical and psychometric properties of the translated and culturally adapted version of the social support questionnaire. A factor analysis with the principal component analysis PCA was used to test construct validity. The internal consistency of items was measured with the Cronbach`s alpha coefficient. RESULTS: After a rigorous translation process the original 20-item questionnaire was adapted into a 19-item version and tested with family caregivers (n = 207) of home-dwelling elderly. Psychometric testing of the German version of the social support questionnaire revealed that the three factors - affirmation, affect and concrete aid - were congruent with the original questionnaire. The accounted variance was 79.5% and the internal consistency determined by the Cronbach's alpha was 0.973. CONCLUSION: The German version of the social support scale of the FAFHES questionnaire is a valid and reliable instrument to assess family perceived support on three dimensions - affirmation, affect and concrete aid - received from nursing professionals. The questionnaire should be tested further in other German-speaking population

Crystal structure of actinide metals at high compression

The crystal structures of some light actinide metals are studied theoretically as a function of applied pressure. The first principles electronic structure theory is formulated in the framework of density functional theory, with the gradient corrected local density approximation of the exchange-correlation functional. The light actinide metals are shown to be well described as itinerant (metallic) f-electron metals and generally, they display a crystal structure which have, in agreement with previous theoretical suggestions, increasing degree of symmetry and closed-packing upon compression. The theoretical calculations agree well with available experimental data. At very high compression, the theory predicts closed-packed structures such as the fcc or the hcp structures or the nearly closed-packed bcc structure for the light actinide metals. A simple canonical band picture is presented to explain in which particular closed-packed form these metals will crystallize at ultra-high pressure

Heat Treatment Effects on the Mechanical Properties and Microstructure of CPM-M4 Tool Steel

Variations in heat treatments have significant effects on the microstructure of tool steels. For CPM-M4 tool steel, the changes in microstructure and mechanical properties were observed based off of variations in temperature. Five heat treatments with constant exposure time and variable austenitizing and tempering temperatures were performed on samples of the CPM-M4. During heat treatment, tool steels undergo microstructural transformations where carbides made up of primary alloying elements are created and grown while the surrounding matrix of material undergoes phase transformations. Using SEM, EBSD, and ImageJ analysis software, the phase fractions of the final microstructure for each treatment was quantified and compared. Changes in mechanical properties were assessed by macro- hardness and nanoindentation. Based on the data, a maximum hardness was achieved for samples with an austenization temperature of 2200°F and a tempering temperature of 925°F. This highest hardness did not correspond to the highest fraction of the hardened carbide and martensite phases. This is due to interactions between both the phases present in the matrix as well as the size and distribution of the carbides

Intrinsic differences between backward and forward vehicle simulation models

Two common methods for predicting the energy usage in vehicles through mathematical\ua0simulation, the `backward\u27 and the `forward\u27 schemes, are discussed and compared in terms\ua0of what longitudinal vehicle behaviour they predict. In the backward scheme, the input driving\ua0cycle is initially assumed to be followed perfectly and therefore the vehicle speed is not a dynamic\ua0state. In the forward scheme, a driver model controls the vehicle in an attempt to follow the\ua0input driving cycle, and the vehicle speed is intrinsically a dynamic state. A theoretical study is\ua0made with a simple mathematical vehicle model, where it is shown that the two methods neither\ua0predict the same expected energy use nor energy variation. Next, the simulation model that isused for the CO2 rating of heavy-duty trucks in Europe, VECTO, is used as an example of the\ua0backward method, and an equivalent implementation in a forward scheme is attempted. Two\ua0numerical experiments are made with these models: a detailed study of the longitudinal vehicle\ua0behaviour on a reference mission; and a study of the predicted CO2 emissions on a family of\ua0stochastically generated missions. The conclusion is that the backward method is easier to use\ua0but the forward method has a greater potential to predict realistic behaviour

Canine distemper virus neutralization activity is low in human serum and it is sensitive to an amino acid substitution in the hemagglutinin protein

© 2015 Elsevier Inc.Serum was analyzed from 146 healthy adult volunteers in eastern Africa to evaluate measles virus (MV) and canine distemper virus (CDV) neutralizing antibody (nAb) prevalence and potency. MV plaque reduction neutralization test (PRNT) results indicated that all sera were positive for MV nAbs. Furthermore, the 50% neutralizing dose (ND50) for the majority of sera corresponded to antibody titers induced by MV vaccination. CDV nAbs titers were low and generally were detected in sera with high MV nAb titers. A mutant CDV was generated that was less sensitive to neutralization by human serum. The mutant virus genome had 10 nucleotide substitutions, which coded for single amino acid substitutions in the fusion (F) and hemagglutinin (H) glycoproteins and two substitutions in the large polymerase (L) protein. The H substitution occurred in a conserved region involved in receptor interactions among morbilliviruses, implying that this region is a target for cross-reactive neutralizing antibodies

Einstein-de Haas torque as a discrete spectroscopic probe allows nanomechanical measurement of a magnetic resonance

The Einstein-de Haas (EdH) effect is a fundamental, mechanical consequence of any temporal change of magnetism in an object. EdH torque results from conserving the object's total angular momentum: the angular momenta of all the specimen's magnetic moments, together with its mechanical angular momentum. Although the EdH effect is usually small and difficult to observe, it increases in magnitude with detection frequency. We explore the frequency-dependence of EdH torque for a thin film permalloy microstructure by employing a ladder of flexural beam modes (with five distinct resonance frequencies spanning from 3 to 208 MHz) within a nanocavity optomechanical torque sensor via magnetic hysteresis curves measured at mechanical resonances. At low DC fields the gyrotropic resonance of a magnetic vortex spin texture overlaps the 208 MHz mechanical mode. The massive EdH mechanical torques arising from this co-resonance yield a fingerprint of vortex core pinning and depinning in the sample. The experimental results are discussed in relation to mechanical torques predicted from both macrospin (at high DC magnetic field) and finite-difference solutions to the Landau-Lifshitz-Gilbert (LLG) equation. A global fit of the LLG solutions to the frequency-dependent data reveals a statistically significant discrepancy between the experimentally observed and simulated torque phase behaviours at spin texture transitions that can be reduced through the addition of a time constant to the conversion between magnetic cross-product torque and mechanical torque, constrained by experiment to be in the range of 0.5 - 4 ns.Comment: 39 pages, 17 figures total (Main: 22 pages, 8 figures; Supplement: 17 pages, 9 figures

Rats distinguish between absence of events and lack of evidence in contingency learning.

The goal of three experiments was to study whether rats are aware of the difference between absence of events and lack of evidence. We used a Pavlovian extinction paradigm in which lights consistently signaling sucrose were suddenly paired with the absence of sucrose. The crucial manipulation involved the absent outcomes in the extinction phase. Whereas in the Cover conditions, access to the drinking receptacle was blocked by a metal plate, in the No Cover conditions, the drinking receptacle was accessible. The Test phase showed that in the Cover conditions, the measured expectancies of sucrose were clearly at a higher level than in the No Cover conditions. We compare two competing theories potentially explaining the findings. A cognitive theory interprets the observed effect as evidence that the rats were able to understand that the cover blocked informational access to the outcome information, and therefore the changed learning input did not necessarily signify a change of the underlying contingency in the world. An alternative associationist account, renewal theory, might instead explain the relative sparing of extinction in the Cover condition as a consequence of context change. We discuss the merits of both theories as accounts of our data and conclude that the cognitive explanation is in this case preferred