Nanoparticle characterization: What to measure?

What to measure? is a key question in nanoscience, and it is not straightforward to address as different physicochemical properties define a nanoparticle sample. Most prominent among these properties are size, shape, surface charge, and porosity. Today researchers have an unprecedented variety of measurement techniques at their disposal to assign precise numerical values to those parameters. However, methods based on different physical principles probe different aspects, not only of the particles themselves, but also of their preparation history and their environment at the time of measurement. Understanding these connections can be of great value for interpreting characterization results and ultimately controlling the nanoparticle structure–function relationship. Here, the current techniques that enable the precise measurement of these fundamental nanoparticle properties are presented and their practical advantages and disadvantages are discussed. Some recommendations of how the physicochemical parameters of nanoparticles should be investigated and how to fully characterize these properties in different environments according to the intended nanoparticle use are proposed. The intention is to improve comparability of nanoparticle properties and performance to ensure the successful transfer of scientific knowledge to industrial real‐world applications

Long-term care use after a stroke or femoral fracture and the role of family caregivers

Background: There has been a shift from institutional care towards home care, and from formal to informal care to contain long-term care (LTC) costs in many countries. However, substitution to home care or informal care might be harder to achieve for some conditions than for others. Therefore, insight is needed in differences in LTC use, and the role of potential informal care givers, across specific conditions. We analyze differences in LTC use of previously independent older patients after a fracture of femur and stroke, and in particular examine to what extent having a partner and children affects LTC use for these conditions. Methods: Using administrative data on Dutch previously independent older people (55+) with a fracture of femur or stroke in 2013, we investigate their LTC use in the year after the condition takes place. We use administrative treatment data to select individuals who were treated by a medical specialist for a stroke or femoral fracture in 2013. Subsequent LTC use is measured as using no formal care, home care, institutional care or being deceased at 13 consecutive four-weekly periods after initial treatment. We relate long-term care use to having a partner, having children, other personal characteristics and the living environment. Results: The probability to use no formal care 1 year after the initial treatment is equally high for both conditions, but patients with a fracture are more likely to use home care, while patients with a stroke are more likely to use institutional care or have died. Having a spouse has a negative effect on home care and institutional care use, but the timing of the effect, especially for institutional care, differs strongly between the two conditions. Having children also has a negative effect on formal care use, and this effect is consistently larger for patients with a fracture than patients with a stroke. Conclusion: As the condition and the effect of potential informal care givers matter for subsequent long-term care use, policy makers should take the expected prevalence of specific conditions within the older people population into account when designing long-term car

Laser furnace and method for zone refining of semiconductor wafers

A method of zone refining a crystal wafer (116 FIG. 1) comprising the steps of focusing a laser beam to a small spot (120) of selectable size on the surface of the crystal wafer (116) to melt a spot on the crystal wafer, scanning the small laser beam spot back and forth across the surface of the crystal wafer (116) at a constant velocity, and moving the scanning laser beam across a predetermined zone of the surface of the crystal wafer (116) in a direction normal to the laser beam scanning direction and at a selectible velocity to melt and refine the entire crystal wafer (116)

Asymmetric nanofluidic grating detector for differential refractive index measurement and biosensing.

Measuring small changes in refractive index can provide both sensitive and contactless information on molecule concentration or process conditions for a wide range of applications. However, refractive index measurements are easily perturbed by non-specific background signals, such as temperature changes or non-specific binding. Here, we present an optofluidic device for measuring refractive index with direct background subtraction within a single measurement. The device is comprised of two interdigitated arrays of nanofluidic channels designed to form an optical grating. Optical path differences between the two sets of channels can be measured directly via an intensity ratio within the diffraction pattern that forms when the grating is illuminated by a collimated laser beam. Our results show that no calibration or biasing is required if the unit cell of the grating is designed with an appropriate built-in asymmetry. In proof-of-concept experiments we attained a noise level equivalent to ∼10(-5) refractive index units (30 Hz sampling rate, 4 min measurement interval). Furthermore, we show that the accumulation of biomolecules on the surface of the nanochannels can be measured in real-time. Because of its simplicity and robustness, we expect that this inherently differential measurement concept will find many applications in ultra-low volume analytical systems, biosensors, and portable devices

U-Pb zircon dating of the Gruf Complex: disclosing the late Variscan granulitic lower crust of Europe stranded in the Central Alps

Permian granulites associated with noritic intrusions and websterites are a common feature of the post-Variscan European crust. Such granulites are common in the Southern Alps (e.g. Ivrea Zone), but occur only in the Gruf Complex in the Central Alps. To understand the geotectonic significance of these granulites, in particular in the context of Alpine migmatisation, zircons from 15 high-grade samples have been U-Pb dated by SHRIMP II analysis. Oscillatory zoned zircons from charnockite sheets, interpreted as melts generated through granulite facies fluid-absent biotite melting at 920-940°C, yield ages of 282-260Ma. Some of these zircons contain inclusions of opx, unequivocally attributable to the granulite facies, thus confirming a Permian age for the charnockites and associated granulites. Two samples from an enclave-rich orthogneiss sheet yield Cambrian and Ordovician zircon cores. Two deformed leucogranites and six ortho- and augengneisses, which compose two-thirds of the Gruf Complex, give zircon ages of 290-260Ma. Most zircons have milky rims with ages of 34-29Ma. These rims date the Alpine amphibolite facies migmatisation, an interpretation confirmed by directly dating a leucosome pocket from upper amphibolite facies metapelites. The Gruf charnockites associated with metre-scale schlieren and boudins of opx-sapphirine-garnet-granulites, websterites and gabbronorites can thus be identified as part of the post-Variscan European lower crust. A geotectonic reconstruction reveals that this piece of lower crust stranded in the (European) North upon rifting of the Neotethys, such contrasting the widespread granulite units in the Southern Alps. Emplacement of the Gruf lower crust into its present-day position occurred during migmatisation and formation of the Bergell Pluton in the aftermath of the breakoff of the European sla

Full counting statistics in a disordered free fermion system

The Full Counting Statistics (FCS) is studied for a one-dimensional system of non-interacting fermions with and without disorder. For two unbiased $L$ site lattices connected at time $t=0$, the charge variance increases as the natural logarithm of $t$, following the universal expression $\approx \frac{1}{\pi^2}\log{t}$. Since the static charge variance for a length $l$ region is given by $\approx \frac{1}{\pi^2}\log{l}$, this result reflects the underlying relativistic or conformal invariance and dynamical exponent $z=1$ of the disorder-free lattice. With disorder and strongly localized fermions, we have compared our results to a model with a dynamical exponent $z \ne 1$, and also a model for entanglement entropy based upon dynamical scaling at the Infinite Disorder Fixed Point (IDFP). The latter scaling, which predicts $\propto \log\log{t}$, appears to better describe the charge variance of disordered 1-d fermions. When a bias voltage is introduced, the behavior changes dramatically and the charge and variance become proportional to $(\log{t})^{1/\psi}$ and $\log{t}$, respectively. The exponent $\psi$ may be related to the critical exponent characterizing spatial/energy fluctuations at the IDFP.Comment: 10 pages, 14 figures; fixed typos; added references; added IDFP scaling based upon reference [1]; added finite bias section; fixed typo

Functional Analysis of Cladosponum fulvum Effector Catalog

Onlangs is de DNA-sequentie van het genoom van Cladosporium fulvum bepaald. Het voornaamste doel daarvan is de identificatie en karakterisering van nieuwe effectors

Prospects for high-z cluster detections with Planck, based on a follow-up of 28 candidates using MegaCam@CFHT

The Planck catalogue of SZ sources limits itself to a significance threshold of 4.5 to ensure a low contamination rate by false cluster candidates. This means that only the most massive clusters at redshift z>0.5, and in particular z>0.7, are expected to enter into the catalogue, with a large number of systems in that redshift regime being expected around and just below that threshold. In this paper, we follow-up a sample of SZ sources from the Planck SZ catalogues from 2013 and 2015. In the latter maps, we consider detections around and at lower significance than the threshold adopted by the Planck Collaboration. To keep the contamination rate low, our 28 candidates are chosen to have significant WISE detections, in combination with non-detections in SDSS/DSS, which effectively selects galaxy cluster candidates at redshifts $z\gtrsim0.5$. By taking r- and z-band imaging with MegaCam@CFHT, we bridge the 4000A rest-frame break over a significant redshift range, thus allowing accurate redshift estimates of red-sequence cluster galaxies up to z~0.8. After discussing the possibility that an overdensity of galaxies coincides -by chance- with a Planck SZ detection, we confirm that 16 of the candidates have likely optical counterparts to their SZ signals, 13 (6) of which have an estimated redshift z>0.5 (z>0.7). The richnesses of these systems are generally lower than expected given the halo masses estimated from the Planck maps. However, when we follow a simplistic model to correct for Eddington bias in the SZ halo mass proxy, the richnesses are consistent with a reference mass-richness relation established for clusters detected at higher significance. This illustrates the benefit of an optical follow-up, not only to obtain redshift estimates, but also to provide an independent mass proxy that is not based on the same data the clusters are detected with, and thus not subject to Eddington bias.Comment: 13 pages, 7 figures. Accepted for publication in A&