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A scanning thermal microscope that uses a fluorescent particle as a temperature probe has been developed. The particle, made of a rare-earth ion-doped fluoride glass, is glued at the extremity of a sharp tungsten tip and scanned on the surface of an electronic device. The temperature of the device is determined by measuring the fluorescence spectrum of the particle at every point on the surface and by comparing the intensity variations of two emission lines. As an example, we will show some images obtained on a nickel stripe 1 microm wide, heated by an electrical current. A good agreement is observed with a simulation of the temperature field on the device.

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Detailed knowledge of the distribution of roots in the soil is important in understanding the extraction of water and nutrients from soil. Various techniques have been developed to monitor root-length density under field conditions. Excavation techniques, including soil cores, have long been considered to give reliable estimates of root-length density, but these techniques are laborious in sample collection and tedious in determination of root lengths. An attractive alternative for monitoring root-length density has been the minirhizotron whereby a periscope is inserted into a clear tube permanently installed in the soil for repeated and rapid measures of root development. The objective of this study was to compare the ability of the minirhizotron technique to measure root-length density as compared to the root-core technique.As in previous studies, substantial disagreement existed between the two techniques in the top 30-cm of the soil. The results from the minirhizotron consistently indicated a much lower root population than the root-core technique in the surface layer of soil. This is especially worrisome because more than 45% of the root-length density was found in this layer with the root-core technique. At deeper soil layers, the minirhizotron data proved to be no less variable than the root-core technique making the determination of statistically significant results difficult. Finally, the relationship between the minirhizotron and soil-core results varied with time even when the observations from the soil surface layer were ignored. Attempts to directly translate minirhizotron observations into a root-length density using a correlation approach would be suspect based on the results of this experiment. * Mention of company names or commercial products does not imply recommendation or endorsement by the United States Department of Agriculture over others not mentioned.

A large number of polyester nanocomposite batches featuring different kinds of nanoclay surface modifiers and up to 6 wt % nanoclay were manufactured using a solvent-based technique. Montmorillonite platelets modified with ammonium ions of different chemical architectures were examined to study the effect of ammonium ions on the extent of surface reactions with long-chain fatty acids. The ammonium montmorillonite was first dispersed and suspended in acetone. This suspension was further esterificated with dotriacontanoic (lacceroic) acid to form high density brushes on the clay surface. This led to achieving higher basal plane spacing of the montmorillonite platelets due to the reduction of electrostatic interactions holding them. The outcome of the surface esterification was analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The esterificated ammonium-modified clays were then mixed by five different mixing strategies based on the use of a three-roll mill mixer (TRM) and/or ultrasonication (US) to obtain the desired polyester-nanoclay dispersion, intercalation, and exfoliation. The dispersion states of the modified nanoclay in polymer were characterized from XRD, scanning electron microscopy (SEM), and low and high magnification transmission electron microscopy (TEM). Mechanical, thermal, and barrier properties of the resulting composites were experimentally characterized. The Mori-Tanaka method along with an orientation distribution function was used to verify the experimental effective stiffness of the polyester nanocomposite systems. The aspect ratio of nanoclays and their level of intercalation and/or exfoliation after mixing were also confirmed by the comparison of the experimental diffusivity results with those of Fick's diffusion model. Systems having 4 and 6 wt % esterificated ammonium nanoclay and prepared according to a combined TRM/US mixing procedure showed optimal performance with balanced properties and processing ease, thereby showing potential for use in the automotive, transportation, and packaging industries.

words)Global warming is projected to cause yield losses due to heat-induced spikelet sterility (HISS) in hot, vulnerable rice-growing regions, but reports documenting HISS at a regional level in the tropics are very limited. As a case study, HISS at flowering was surveyed under field conditions using local popular varieties in Savannakhet, Lao PDR, and Tamil Nadu, India, during the dry season. At the field site in Savannakhet, sterility in variety Thadokkham1 (TDK1) was 10.8% when the maximum average temperature at heading was 32.9 °C, which increased to 23.3% at 37.3 °C. When plots were covered with a shading net, solar radiation was reduced by 60% at heading, which significantly reduced sterility to 10.0%. Panicle temperature estimates produced with a micrometeorology model revealed that shading during the hours when flowering occurs decreased panicle temperature by 2.2-2.6 °C. At the field sites in Tamil Nadu, sterility of variety Coimbatore 51 (CO51) was highly correlated with the maximum temperature at heading; sterility was around 5-10% when maximum average temperature was below 36.5 °C, which increased to 33.4% at 38.0 °C. Marking of opened spikelets at hourly intervals allowed us to detect increases in sterility as temperature increased from early morning until noon. We conclude that HISS at flowering can occur in local popular varieties grown in Savannakhet and Tamil Nadu during the hot, dry season. Effective protocols such as using a shading net and hourly marking of open spikelets are useful approaches to quantifying HISS during flowering across hot and potential heat-vulnerable rice-growing regions.

We report a demonstration video-rate heterodyne holography in off-axis configuration. Reconstruction and display of 1 Megapixel holograms is achieved at 24 frames per second, with a graphics processing unit. Our claims are validated with real-time screening of steady-state vibration amplitudes in a wide-field, non-contact vibrometry experiment. c 2018 Optical Society of America OCIS codes: 090.1995, 280.3340 The laser Doppler method is the most common optical interferometry technique used for non-contact measurements of mechanical vibrations. Though highly effective for single-point vibration analysis, this technique is much less adapted to wide-field imaging than holography. Homodyne [1][2][3] and heterodyne [4][5][6] holographic recordings in off-axis configuration enabled reliable measurements of mechanical vibrations, but none of them allowed real-time monitoring, which is an essential feature. Matching the display rate of opticallymeasured Megapixel digital holograms with real-time imaging standards is demanding in terms of computational power. Holographic measurements are performed in a diffraction plane. Hence, image formation requires to simulate the back-propagation of an optical field. Such propagation involves turning the data measured in the plane of an array detector into a reciprocal plane with at least one bi-dimensional numerical Fourier transformation, typically a Fast-Fourier transform (FFT). Recently, real-time display of digital holograms with Graphics Processing Units (GPUs) [7,8] has alleviated the issue of the high computational workload needed for such image reconstruction. Parallel computations on GPU consistently increase the throughput with respect to CPU for computer-generated holograms, which demonstrated the performance of GPUs in streamline image processing [9], [10].In this letter, we report an experimental demonstration of an image acquisition scheme designed to perform video-rate image reconstruction and display from heterodyne holographic measurements on a 1 Megapixel sensor array. Image reconstruction of steady-state vibration modes up to 100 kHz at a rate of 24 images per second is achieved. GPU processing is shown to enable holographic reconstruction and display with 3 FFT calculations per recorded frame, which covers the processing throughput needs of three reconstruction approaches : the convolution, angular spectrum, and Fresnel transform methods [11].The acquisition setup consists of an off-axis, frequency-shifting holographic scheme, used to perform a multipixel heterodyne detection of optical modulation sidebands. Optical heterodyning is a process for placing information at frequencies of interest (e.g. the mechanical vibration of an object under investigation) into a useful frequency range by mixing the frequency content of the probe beam with a reference (or local oscillator, LO) beam. The optical frequency of the reference beam is shifted to generate a beat frequency of the interference pattern within the sensor bandwidth, which carries the information at the or...