Deformation mechanism of neutron irradiated Al-B based on SEM-DIC

The electron backscatter diffraction (EBSD) characterization of irradiated Al-B shows that there is a high concentration defect region around the borides. Nanoscale speckle particles were successfully prepared on the surface of Al-B before and after irradiation, and then the mesoscale strain during in-situ deformation was obtained by digital image correlation (DIC) technique. The results shows that slip band bypass such an area through cross slips with slip band deflection. Transmission electron microscopy (TEM) indicates that abundant helium bubbles exist in the deflected slip band area pinning the dislocations.

The surface of (4) Vesta in visible light as seen by Dawn/VIR

Aims. We analyzed the surface of Vesta at visible wavelengths, using the data of the Visible and InfraRed mapping spectrometer (VIR) on board the Dawn spacecraft. We mapped the variations of various spectral parameters on the entire surface of the asteroid, and also derived a map of the lithology. Methods. We took advantage of the recent corrected VIR visible data to map the radiance factor at 550 nm, three color composites, two spectral slopes, and a band area parameter relative to the 930 nm crystal field signature in pyroxene. Using the howardite-eucrite-diogenite meteorites data as a reference, we derived the lithology of Vesta using the variations of the 930 and 506 nm (spin-forbidden) band centers observed in the VIR dataset. Results. Our spectral parameters highlight a significant spectral diversity at the surface of Vesta. This diversity is mainly evidenced by impact craters and illustrates the heterogeneous subsurface and upper crust of Vesta. Impact craters also participate directly in this spectral diversity by bringing dark exogenous material to an almost entire hemisphere. Our derived lithology agrees with previous results obtained using a combination of infrared and visible data. We therefore demonstrate that it is possible to obtain crucial mineralogical information from visible wavelengths alone. In addition to the 506 nm band, we identified the 550 nm spin-forbidden one. As reported by a laboratory study for synthetic pyroxenes, we also do not observe any shift of the band center of this feature across the surface of Vesta, and thus across different mineralogies, preventing use of the 550 nm spin-forbidden band for the lithology derivation. Finally, the largest previously identified olivine rich-spot shows a peculiar behavior in two color composites but not in the other spectral parameters.

Spectral and Growth Characteristics of Willows and Maize in Soil Contaminated with a Layer of Crude or Refined Oil

Remote sensing holds great potential for detecting stress in vegetation caused by hydrocarbons, but we need to better understand the effects of hydrocarbons on plant growth and specific spectral expression. Willow (Salix viminalis var. Tora) cuttings and maize (Zea mays var. Lapriora) seedlings were grown in pots of loam soil containing a hydrocarbon-contaminated layer at the base of the pot (crude or refined oil) at concentrations of 0.5, 5, or 50 g·kg−1. Chlorophyll concentration, biomass, and growth of plants were determined through destructive and nondestructive sampling, whilst reflectance measurements were made using portable hyperspectral spectrometers. All biophysical (chlorophyll concentration and growth) variables decreased in the presence of high concentrations of hydrocarbons, but at lower concentrations an increase in growth and chlorophyll were often observed with respect to nonpolluted plants, suggesting a biphasic response to hydrocarbon presence. Absorption features were identified that related strongly to pigment concentration and biomass. Variations in absorption feature characteristics (band depth, band area, and band width) were dependent upon the hydrocarbon concentration and type, and showed the same biphasic pattern noted in the biophysical measurements. This study demonstrates that the response of plants to hydrocarbon pollution varies according to hydrocarbon concentration and that remote sensing has the potential to both detect and monitor the variable impacts of pollution in the landscape.

Infrared Refraction Spectroscopy

We suggest a new modality of infrared spectroscopy termed Infrared Refraction Spectroscopy, which is complimentary to absorption spectroscopy. The beauty of this new modality lies not only in its simplicity but also in the fact that it closes an important gap: It allows to quantitatively interpret reflectance spectra by simplest means. First, the refractive index spectrum is calculated from reflectance by neglecting absorption. The change of the refractive index is proportional to concentration, and the spectra with features similar to second derivative absorbance spectra can simply be computed by numerically deriving the refractive index spectra, something which can be easily carried out by standard spectra software packages. The peak values of the derived spectra indicate oscillator positions and are approximately proportional to the concentration in a similar way as absorbance is. In contrast to absorbance spectra, there are no baseline ambiguities for first derivative refractive index spectra, and in refractive index spectra, instead of integrating over a band area, a simple difference of two refractive index values before and after an absorption leads to a quantity that correlates perfectly linearly with concentration in the absence of local field effects.

Raman Spectroscopic Study on a CO2-CH4-N2 Mixed-Gas Hydrate System

Accurate determination of the characteristics of coal mine gas separation products is the key for gas separation applications based on hydrate technology. Gas hydrates are synthesized from gases with two types of compositions (CO2-CH4-N2). The separation products were analyzed by in situ Raman spectroscopy. The crystal structure of the mixed-gas hydrate was determined, and the cage occupancy and hydration index were calculated based on the various vibrational modes of the molecules according to the “loose cage-tight cage” model and the Raman band area ratio combined with the van der Waals-Platteeuw model. The results show that the two mixed-gas hydrate samples both have a type I structure. Large cages of mixed-gas hydrate are mostly occupied by guest molecules, with large cage occupancies of 98.57 and 98.52%; however, small cages are not easy to occupy, with small cage occupancies of 29.93 and 33.87%. The average cage occupancies of these two hydrates are 81.41 and 82.36%, and the stability of the crystal structure of the mixed-gas hydrate in the presence of 75% CO2 is better than that of the mixed-gas hydrate in the presence of 70% CO2. The hydration indices of the two hydrate gas samples are 7.14 and 6.98, which are greater than the theoretical value of structure l.

Adaptive Sparse Detector for Suppressing Powerline Component in EEG Measurements

Powerline interference (PLI) is a major source of interference in the acquisition of electroencephalogram (EEG) signal. Digital notch filters (DNFs) have been widely used to remove the PLI such that actual features, which are weak in energy and strongly connected to brain states, can be extracted explicitly. However, DNFs are mathematically implemented via discrete Fourier analysis, the problem of overlapping between spectral counterparts of PLI and those of EEG features is inevitable. In spite of their effectiveness, DNFs usually cause distortions on the extracted EEG features, which may lead to incorrect diagnostic results. To address this problem, we investigate an adaptive sparse detector for reducing PLI. This novel approach is proposed based on sparse representation inspired by self-adaptive machine learning. In the coding phase, an overcomplete dictionary, which consists of redundant harmonic waves with equally spaced frequencies, is employed to represent the corrupted EEG signal. A strategy based on the split augmented Lagrangian shrinkage algorithm is employed to optimize the associated representation coefficients. It is verified that spectral components related to PLI are compressed into a narrow area in the frequency domain, thus reducing overlapping with features of interest. In the decoding phase, eliminating of coefficients within the narrow band area can remove the PLI from the reconstructed signal. The sparsity of the signal in the dictionary domain is determined by the redundancy factor. A selection criteria of the redundancy factor is suggested via numerical simulations. Experiments have shown the proposed approach can ensure less distortions on actual EEG features.

Calcium fixation on fortified rice made with various rice varieties

The aim of this study was to evaluate calcium fixation and calcium binding in calciumfortified rice. Calcium-fortified rice was made by soaking (infusing) rice in a Ca-lactate or Ca-gluconate solution at temperature of 80oC for 20 mins. The rice types used in this study were low-, medium- and high amylose rice, represented by Memberamo, Ciherang and IR-42 rice varieties. Calcium retention in rice was tested by washing and dialysis, and calcium levels in the rice were determined by Atomic Absorption Spectroscopy. Calcium fixation was determined by using an FT-IR infrared spectrometer based on the changes in infrared spectra of the functional groups of -OH and C-O. The research showed that calcium retention in rice after washing was between 86.23% - 94.38% (Ca-lactate) and 89.37% - 90.15% (Ca-gluconate), Ca retention after dialysis was between 37.49% to 44.13% (Ca-lactate) and 37.40% to 42.86% (Ca-gluconate). The addition of Ca-lactate or Ca-gluconate to rice caused a decrease in the absorbance value and the absorption band area square at a wave numbers 3425 cm-1 (-OH group) and 1300-1000 cm-1 (C-O stretching vibration). Based on these data and the retention of Ca2+ after washing and dialysis, the Ca2+ in fortified-rice was bound by hydrogen bonding to form Ca-hydrate and by ionicdipole bonding with –OH group of starch molecules, and/or trapping in gelatinized starch.

The importance of the surface roughness and running band area on the bottom of a stone for the curling phenomenon

Curling is a sport in which players deliver a cylindrical granite stone on an ice sheet in a curling hall toward a circular target located 28.35 m away. The stone gradually moves laterally, or curls, as it slides on ice. Although several papers have been published to propose a mechanism of the curling phenomenon for the last 100 years, no established theory exists on the subject, because detailed measurements on a pebbled ice surface and a curling stone sliding on ice and detailed theoretical model calculations have yet to be available. Here we show using our precise experimental data that the curl distance is primarily determined by the surface roughness and the surface area of the running band on the bottom of a stone and that the ice surface condition has smaller effects on the curl distance. We also propose a possible mechanism affecting the curling phenomena of a curing stone based on our results. We expect that our findings will form the basis of future curling theories and model calculations regarding the curling phenomenon of curling stones. Using the relation between the curl distance and the surface roughness of the running band in this study, the curl distance of a stone sliding on ice in every curling hall can be adjusted to an appropriate value by changing the surface roughness of the running band on the bottom of a stone.

Temperature dependent mid-infrared (5-25 μm) reflectance spectroscopy of carbonaceous meteorites and minerals: implication for remote sensing in Solar System exploration.

<p>Interpretation of spectroscopic data from remote sensing strongly depends on the spectroscopic properties, particle size and temperature of materials on the observed surface. Spectral indices of silicates, carbonates, sulfates, oxides and chemicals available on public database are commonly obtained at room temperature and pressure. Whether temperature can affect spectral properties of minerals such as the peak position, band area and shape, was advanced decades ago (Singer & Roush, 1985), but a systematic laboratory study on such effects is still missing. Hitherto, few studies were performed analyzing the effects of space environment, such as low pressure and temperature, on spectroscopic features of minerals, mostly focusing on near infrared spectral region (Moroz, et al. 2000; Hinrichs & Lucey 2002; De Angelis, et al. 2019). This is especially lacking in the mid-infrared region, where laboratory data are almost completely absent. Thus, it is pivotal to acquire spectra in vacuum at various temperatures and varying the particle sizes, for better simulating space environmental conditions.</p><p>Our apparatus at INAF-Astrophysical Observatory of Arcetri allows reflectance measurements in an extended spectral range from VIS to far IR and at temperatures ranging from 64 K to 500 K. We present here a detailed analysis on temperature-dependent variation on mineral and carbonaceous chondrite samples in the spectral range 1500-400 cm<sup>-1</sup> (6.6-25 µm in wavelength). Mineral phases and meteorites analyzed are: pyroxene, olivine, serpentine, Tagish Lake (CI2-ungruped), Aguas Zarcas (CM2) and Orgueil (CI1). Samples are prepared with particle sizes <20 μm, <200 μm, and 200-500 μm. Our results show that temperature induces spectral features modifications such as peak position shifts, band area and peak intensity changes (Fig 1). Modifications are reversible with temperature and the trend of variation is related to the sample composition and hydration level. Moreover, magnitude of temperature-dependent spectroscopic changes is strongly linked with grain size and composition, hence making this type of analysis pivotal for a correct interpretation of data collected by space telescopes and orbital spacecrafts.</p><p> </p><p><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.b99a2d2ef2fe55803892951/sdaolpUECMynit/0202CSPE&app=m&a=0&c=eb4e74f18ee6e81cf082f62ce54b5556&ct=x&pn=gnp.elif" alt=""></p><p><em><strong>Figure 1</strong> Meteorite spectra at different temperature normalized at 1500 cm<sup>-1</sup> in wavenumber range between 1500 cm<sup>-1</sup> and 400 cm<sup>-1</sup>. Tagish Lake (top left panel), Orgueil (top right panel) and Aguas Zarcas (bottom left panel). All samples are sieved in grain size 200-500 µm. Spectra were acquired at different temperature step from 65 K (light blue) to 350 K (red). Position of Christiansen features (CF) and Reststrahlen bands (RB) are highlighted.</em></p><p> </p><p><strong>References<br></strong>De Angelis, S., et al. 2019. Icarus, 317, 388-411<br>Hinrichs, J. L. & Lucey, P. G., 2002. Icarus, 155, 169-180<br>Moroz, L., Schade, U. & Wash, R., 2000. Icarus, 147, 79-93.<br>Singer, R. B. & Roush, T. L., 1985. Journal of Geophysical Research, 90 (B14), 12434-12444.</p>

In situ effective snow grain size mapping using a compact hyperspectral imager

Effective snow grain radius (re) is mapped at high resolution using near-infrared hyperspectral imaging (NIR-HSI). The NIR-HSI method can be used to quantify re spatial variability, change in re due to metamorphism, and visualize water percolation in the snowpack. Results are presented for three different laboratory-prepared snow samples (homogeneous, ice lens, fine grains over coarse grains), the sidewalls of which were imaged before and after melt induced by a solar lamp. The spectral reflectance in each ~3 mm pixel was inverted for re using the scaled band area of the ice absorption feature centered at 1030 nm, producing re maps consisting of 54 740 pixels. All snow samples exhibited grain coarsening post-melt as the result of wet snow metamorphism, which is quantified by the change in re distributions from pre- and post-melt images. The NIR-HSI method was compared to re retrievals from a field spectrometer and X-ray computed microtomography (micro-CT), resulting in the spectrometer having the same mean re and micro-CT having 23.9% higher mean re than the hyperspectral imager. As compact hyperspectral imagers become more widely available, this method may be a valuable tool for assessing re spatial variability and snow metamorphism in field and laboratory settings.