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Pallabi Sil Paul,1 Mallesh Rathnam,1 Aria Khalili,2 Leonardo M Cortez,1 Mahalashmi Srinivasan,3 Emmanuel Planel,4 Jae-Young Cho,2,5 Holger Wille,3 Valerie L Sim,1 Sue-Ann Mok,3 Satyabrata Kar1 1Department of Medicine (Neurology), Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta, T6G 2M8, Canada; 2Quantum and Nanotechnology Research Centre, National Research Council Canada, Edmonton, Alberta, Canada; 3Department of Biochemistry, Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta, Canada; 4Department of Psychiatry and Neurosciences, University of Laval, Quebec, Canada; 5Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, CanadaCorrespondence: Satyabrata Kar, Department of Medicine (Neurology), Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta, T6G 2M8, Canada, Tel +1-780-492-9357, Fax +1-780-492-9352, Email skar@ualberta.caIntroduction: Hyperphosphorylation and aggregation of the microtubule-associated tau protein, which plays a critical role in many neurodegenerative diseases (ie, tauopathies) including Alzheimer’s disease (AD), are known to be regulated by a variety of environmental factors including temperature. In this study we evaluated the effects of FDA-approved poly (D,L-lactide-co-glycolic) acid (PLGA) nanoparticles, which can inhibit amyloid-β aggregation/toxicity in cellular/animal models of AD, on temperature-dependent aggregation of 0N4R tau isoforms in vitro.Methods: We have used a variety of biophysical (Thioflavin T kinetics, dynamic light scattering and asymmetric-flow field-flow fractionation), structural (fluorescence imaging and transmission electron microscopy) and biochemical (Filter-trap assay and detection of soluble protein) approaches, to evaluate the effects of native PLGA nanoparticles on the temperature-dependent tau aggregation.Results: Our results show that the aggregation propensity of 0N4R tau increases significantly in a dose-dependent manner with a rise in temperature from 27°C to 40°C, as measured by lag time and aggregation rate. Additionally, the aggregation of 2N4R tau increases in a dose-dependent manner. Native PLGA significantly inhibits tau aggregation at all temperatures in a concentration-dependent manner, possibly by interacting with the aggregation-prone hydrophobic hexapeptide motifs of tau. Additionally, native PLGA is able to trigger disassembly of preformed 0N4R tau aggregates as a function of temperature from 27°C to 40°C.Conclusion: These results, taken together, suggest that native PLGA nanoparticles can not only attenuate temperature-dependent tau aggregation but also promote disassembly of preformed aggregates, which increased with a rise of temperature. Given the evidence that temperature can influence tau pathology, we believe that native PLGA may have a unique potential to regulate tau abnormalities associated with AD-related pathology. Keywords: tau protein, PLGA nanoparticles, tau pathology, protein aggregation

The present work reports the unconventional exchange bias (EB) phenomena in an exchange-coupled hard and soft magnetic bilayer system and the tunability of EB. The EB phenomena, i.e., shifting of the hysteresis loop of the soft (Fe) layer is observed when the hard magnetic ( L 1 0 FePt) layer is under the remanent state indicating the development of unidirectional anisotropy. The nuclear resonant scattering measurements clearly reveal the development of unidirectional anisotropy in the soft magnetic (Fe) layer, when the hard magnetic layer is under the remanent state. The magnetization reversal process is investigated by measuring two in-plane orthogonal components of magnetization, i.e., parallel ( M ∥) and perpendicular ( M ⊥ ) to the applied field using the magneto-optical Kerr effect (MOKE). When the magnetic field is applied parallel (antiparallel) to the biasing field direction, ( H SAT ) magnetization reversal is nonuniform, and on the other hand, the rotation of magnetization is observed when the magnetic field is applied away from the H SAT direction. In addition, the sign inversion of the M ⊥ component is observed when the magnetic field is applied at the same angle on either side of the H SAT direction, which clearly imply the change in handedness of the chirality of spin structure during the magnetization reversal of the soft layer. Further, it is observed that the EB decreases with the increase of soft magnetic (Fe) layer thickness, demonstrating the tunable nature of EB phenomena even in these unconventional systems. [ABSTRACT FROM AUTHOR]

Ceilometer technology is increasingly applied to the monitoring and the characterization of tropospheric aerosols. In this work, a method to estimate some key aerosol parameters (extinction coefficient, surface area concentration and volume concentration) from ceilometer measurements is presented. A numerical model has been set up to derive a mean functional relationships between backscatter and the above mentioned parameters based on a large set of simulated aerosol optical properties. A good agreement was found between the modeled backscatter and extinction coefficients and the ones measured by the EARLINET Raman lidars. The developed methodology has then been applied to the measurements acquired by a prototype Polarization Lidar-Ceilometer (PLC). This PLC instrument was developed within the EC- LIFE+ project “DIAPASON” as an upgrade of the commercial, single-channel Jenoptik CHM15k system. The PLC run continuously (h24) close to Rome (Italy) for a whole year (2013-2014). Retrievals of the aerosol backscatter coefficient at 1064 nm and of the relevant aerosol properties were performed using the proposed methodology. This information, coupled to some key aerosol type identification made possible by the depolarization channel, allowed a year-round characterization of the aerosol field at this site. Examples are given to show how this technology coupled to appropriate data inversion methods is potentially useful in the operational monitoring of parameters of air quality and meteorological interest.

We report on the characterization of high quality sapphire single crystals suitable for high-resolution X-ray optics at high energy. Investigations using rocking curve imaging reveal the crystals to be of uniformly good quality at the level of ~10-4 in lattice parameter variations, δd=d. However, investigations using backscattering rocking curve imaging with a lattice spacing resolution of δd/d ~ 5×10-8 show very diverse quality maps for all crystals. Our results highlight nearly ideal areas with an edge length of 0.2-0.5mm in most crystals, but a comparison of the back reflection peak positions shows that even neighboring ideal areas exhibit a relative difference in the lattice parameters on the order of δd/d = ¼ 10-20x10-8; this is several times larger than the rocking curve width. Stress-strain analysis suggests that an extremely stringent limit on the strain at a level of ~100 kPa in the growth process is required in order to produce crystals with large areas of the quality required for X-ray optics at high energy. [ABSTRACT FROM AUTHOR]

Ultra-thin Fe film is deposited obliquely on the Tris(8-hydroxyquinolinato) aluminum (Alq3) layer to study the interface magnetism and compared with the normally deposited film of the same thickness. The overall magnetic property of the film, as observed using magneto-optic Kerr effect measurements, is understood precisely through interface resolved grazing incident nuclear resonance scattering (GINRS) measurements under x-ray standing wave (XSW) conditions. To excite XSW modes, the bilayer is deposited between high dense Ag and Pt layers to make a waveguide structure, where the position of the antinode is varied by changing incident angles. The Fe layer is enriched with 57Fe isotope during deposition to make it active for GINRS measurements. Compared with obliquely deposited 57Fe film, reduced hyperfine fields at the interface of normally deposited 57Fe/Alq3 film, providing evidence for the deep penetration of 57Fe atoms into Alq3 film. Due to the large shadowing effect at oblique angle deposition, Fe atoms try to organize into isolated superparamagnetic clusters to minimize their surface/interface energy. On the other hand, besides the relatively deep penetration in the normally deposited thin film, ferromagnetism is observed due to the connecting bigger 57Fe clusters. Our results demonstrate that deposition geometry has a direct and crucial bearing on the interfacial microstructure, which can control diffusion at the Alq3 interfaces and tune magnetic anisotropy in the ferromagnetic layer. [ABSTRACT FROM AUTHOR]

FeCoB/MgO bilayer is prepared to study the interface magnetism and its role in azimuthal angle-dependent magnetic properties. As observed in magneto-optic Kerr effect measurements, unusual hysteresis loops are understood precisely through interface resolved grazing incident nuclear resonance scattering (GINRS) measurements under x-ray standing wave (XSW) conditions. To excite XSW modes, the bilayer is deposited between a Pt waveguide structure, where the position of the anti-nodes is varied by changing incident angles. As GINRS is an isotope sensitive technique, the FeCoB layer is enriched with 57Fe isotope during deposition. The formation of a high-density 57FeCoB layer at the 57FeCoB/MgO interface with a hyperfine field ~34.25 T is found and attributed to the increasing volume of FeCo at the interface. Boron diffusion from 57FeCoB to the MgO layer is found to be responsible for FeCo rich FeCoB layer near the interface. The azimuthal angle-dependent unusual shape of hysteresis loops is described in terms of coupled magnetization reversal between the bulk and interface parts of FeCoB layer. In contrast to some studies in literature, no evidence of the formation of an oxide layer is observed at the interface. [ABSTRACT FROM AUTHOR]

The isotope selective grazing-incidence nuclear resonance scattering (GI-NRS) technique, which is a time analog to Mössbauer spectroscopy, is made depth resolved to probe the magnetism of the diffused Fe (Fediffused) and bulk Fe (Febulk) parts of the layer in an Fe/Alq3 [ferromagnetic (FM)/organic semiconductor (OSC)] bilayer structure. On the basis of theoretical simulations, it is demonstrated that the antinode regions of x-ray standing waves (XSWs) generated through wave guide structures allow one to measure the Fediffused and Febulk parts independently, providing evidence for a diffused layer with reduced electron density and hyperfine fields. Due to possible small isolated clusters of Fe in the diffused layer, Fe moments are found with random orientations, while in Febulk moments, they are aligned in the film plane due to shape anisotropy. GI-NRS under XSW is suitable for FM/OSC structures to obtain interface resolved magnetic information, which is otherwise difficult with any other available lab based conventional methods. [ABSTRACT FROM AUTHOR]

Three experiments are reviewed, performed (in 2014–2016) at ID18 of ESRF to measure the influence of acceleration on time dilation by measuring the relative shift between the absorption lines of two states of the same rotating absorber with accelerations anti‐parallel and parallel to the incident beam. Statistically significant data for rotation frequencies up to 510 Hz in both directions of rotation were collected. For each run with high rotation, a stable statistically significant 'vibration‐free' relative shift between the absorption lines of the two states was measured. This may indicate the influence of acceleration on time dilation. However, the measured relative shift was also affected by the use of a slit necessary to focus the beam to the axis of rotation to a focal spot of sub‐micrometre size. The introduction of the slit broke the symmetry in the absorption lines due to the nuclear lighthouse effect and affected the measured relative shift, preventing to claim conclusively the influence of acceleration on time dilation. Assuming that this loss of symmetry is of first order, the zero value of the relative shift, corrected for this loss, falls always within the experimental error limits, as predicted by Einstein's clock hypothesis. The requirements and an indispensable plan for a conclusive experiment, once the improved technology becomes available, is presented. This will be useful to future experimentalists wishing to pursue this experiment or a related rotor experiment involving a Mössbauer absorber and a synchrotron Mössbauer source. An indispensable plan, requirements and challenges to overcome for a conclusive experiment to test time dilation due to acceleration, based on three experiments at ESRF, is presented. [ABSTRACT FROM AUTHOR]

Introduces a simulation procedure describing the low-pressure chemical vapor deposition of silicon dioxide on structured wafer surfaces. Description on the redistribution model; Algorithm underlying the simulation program; Conclusion on the formation and concentration of the deposition precursor.

The influence of strain on the magnetic and dynamic properties of ARMCO iron has been characterized by Mössbauer spectroscopy and by Nuclear Inelastic Scattering of synchrotron radiation. The Mössbauer spectra, taken in backscattering geometry, reveal that the magnetic texture in these materials is depending on the type of mechanical loading, monotonic or cyclic, respectively. The applicability of Nuclear Inelastic Scattering for the investigation of the dynamic properties of these macroscopic bulk-engineering materials is shown. The so obtained phonon density of states of a monotonically loaded specimen shows slight differences in its shape and spectral features in comparison to the initial state. An influence of dislocations is also reflected in theoretically calculated phonon density of states based on classical molecular dynamics simulations. [ABSTRACT FROM AUTHOR]

A novel sample environment enabling optical pump - nuclear resonance probe experiments has been installed at the beamline P01, Petra III, DESY Hamburg. This set-up has been used to investigate optically induced spin state changes of spin crossover (SCO) complexes by nuclear resonant scattering immediately after excitation by an optical laser pulse. Here, we report the technical details as well as first results of the experiments performed at 290 K and 80 K on the SCO complexes [Fe (NHtrz)]Cl and [Fe(PM-BiA)(NCS)], respectively. The Fe-enriched SCO complexes were excited by a 531 nm laser with a pulse length < 100 ps. Evaluation of the nuclear forward scattering data clearly indicate the presence of high spin (HS) states when the complexes are excited by laser pulses and a pure low spin (LS) state in the absence of any laser pulse. Furthermore, the dependence of the optically excited HS-fraction has been determined as a function of the average optical power. [ABSTRACT FROM AUTHOR]

New results, additional techniques and know-how acquired, developed and employed in a recent HC-1898 experiment at the Nuclear Resonance Beamline ID18 of ESRF are presented, in the quest to explore the acceleration effect on time dilation. Using the specially modified Synchrotron Mössbauer Source and KB-optics together with a rotating single-line semicircular Mössbauer absorber on the rim of a specially designed rotating disk, the aim was to measure the relative spectral shift between the spectra of two states when the acceleration of the absorber is anti-parallel and parallel to the source. A control system was used for the first time and a method to quantify the effects of non-random vibrations on the spectral shift was developed. For several runs where the effect of these vibrations was negligible, a stable statistically significant non-zero relative shift was observed. This suggests the influence of acceleration on time. [ABSTRACT FROM AUTHOR]

Many Mössbauer spectroscopy (MS) experiments have used a rotating absorber in order to measure the second-order transverse Doppler (TD) shift, and to test the validity of the Einstein time dilation theory. From these experiments, one may also test the clock hypothesis (CH) and the time dilation caused by acceleration. In such experiments the absorption curves must be obtained, since it cannot be assumed that there is no broadening of the curve during the rotation. For technical reasons, it is very complicated to keep the balance of a fast rotating disk if there are moving parts on it. Thus, the Mössbauer source on a transducer should be outside the disk. Friedman and Nowik have already predicted that the X-ray beam finite size dramatically affects the MS absorption line and causes its broadening. We provide here explicit formulas to evaluate this broadening for a synchrotron Mössbauer source (SMS) beam. The broadening is linearly proportional to the rotation frequency and to the SMS beam width at the rotation axis. In addition, it is shown that the TD shift and the MS line broadening are affected by an additional factor assigned as the alignment shift which is proportional to the frequency of rotation and to the distance between the X-ray beam center and the rotation axis. This new shift helps to align the disk's axis of rotation to the X-ray beam's center. To minimize the broadening, one must focus the X-ray on the axis of the rotating disk and/or to add a slit positioned at the center, to block the rays distant from the rotation axis of the disk. Our experiment, using the 57Fe SMS, currently available at the Nuclear Resonance beamline (ID18) at the ESRF, with a rotating stainless steel foil, confirmed our predictions. With a slit installed at the rotation axis (reducing the effective beam width from 15.6 µm to 5.4 µm), one can measure a statistically meaningful absorption spectrum up to 300 Hz, while, without a slit, such spectra could be obtained up to 100 Hz only. Thus, both the broadening and the alignment shift are very significant and must be taken into consideration in any rotating absorber experiment. Here a method is offered to measure accurately the TD shift and to test the CH. [ABSTRACT FROM AUTHOR]

We have measured the polarization purity of undulator radiation at 12.9 keV, with hitherto unachievable precision. We could measure a polarization purity of 1.8×10-4 by using a silicon channel-cut crystal with six Bragg reflections at 45¯ as analyzer. [ABSTRACT FROM AUTHOR]

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The article presents a study on the milli-electronvolt monochromatization of hard x-ray optics using a sapphire backscattering monochromator. It mentions that the sapphire monochromator was tested with the energies of several nuclear resonances. It notes that the isotopes of sapphire crystals are also applied in nuclear inelastic scattering.

Focuses on the precise measurement of the lattice parameters of α-Al[sub2]O[sub3] in the temperature range 4.5--250 K using the Mössbauer wavelength standard. Methodology used to study the analysis; Experimental observation of the analysis; Data evaluation of the analysis.