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A compact low-energy and high-intensity x-ray source for radiation biology applications is presented. A laser-induced plasma moves inside a 30 kV diode and produces a beam of 1014 electrons at the anode location. An aluminum foil converts a part of the energy of these electrons into x-ray photons, which are characterized using filtered imaging plates. The dose that would be deposited by these x-ray photons in C. elegans larvae is calculated from Geant4 simulations. It can be set to a value ranging between 10 μGy and 10 mGy per laser shot by simply changing the aluminum foil thickness and the diode voltage. Therefore, this versatile and compact x-ray source opens a new path to explore the radiation effects induced by dose rates varying over several orders of magnitude. [ABSTRACT FROM AUTHOR]

Size-controllable aluminum nanoconcave arrays were synthesized by electrochemical anodization of high and low-purity aluminum foils using oxalic, phosphoric, and citric acids. The plasmonic properties of the nanoconcave arrays in the two types of Al were investigated based on the specular reflectance in the 190–1400 nm wavelength range. We found that their optical reflectance was dramatically reduced as compared with unstructured Al. At the same time, pronounced reflectivity dips were detectable in the 280–1250 nm wavelength range for the case of high-purity aluminum, while for low-purity aluminum, they were within 260–580 nm, which were ascribed to plasmonic resonances of first and second orders. As a proof of principle of an application, we placed graphene on top of the nanoconcave arrays and observed a Surface Enhanced Raman Scattering (SERS) effect that resulted in an intensity increase in the characteristic G and 2D bands of graphene induced by the plasmonic properties of Al nanoconcave arrays. The maximum increase was achieved when the plasmonic resonance almost matched with the wavelength of the excitation laser probe of the Raman system. This study is important since we used low purity aluminum at a low cost to design and fabricate SERS substrates which can be used in practical applications. [ABSTRACT FROM AUTHOR]

A thin planar acoustic lens composed of concentric annular slits on a circular steel plate covered by a membrane made up of aluminum foil is numerically designed, and its performance in focusing low-frequency sound in air is experimentally demonstrated. Resonant fundamental modes of the membrane-backed cavities are calculated via the Finite-Element Method. By carefully adjusting the radii of the concentric cavities, the phase discontinuity across the cavities can be employed to achieve constructive interference of sound waves at a focal length of 200 mm, which is close to the acoustic wavelength, at 2190 Hz. The designed lens has an overall radius which is approximately one fourth of the radius of a conventional acoustic Fresnel lens employing a wavelength path length difference between adjacent cavities. [ABSTRACT FROM AUTHOR]

Using an infrared camera for thermographic imaging allows the contactless temperature measurement of many surface pixels simultaneously. From the measured surface data, the structure below the surface, embedded inside a sample or tissue, can be reconstructed and imaged, if heated by an excitation light pulse. The main drawback in active thermographic imaging is the degradation of the spatial resolution with the imaging depth, which results in blurred images for deeper lying structures. We circumvent this degradation by using blind structured illumination combined with a non-linear joint sparsity reconstruction algorithm. We demonstrate imaging of a line pattern and a star-shaped structure through a 3mm thick steel sheet with a resolution four times better than the width of the thermal point-spread-function. The structured illumination is realized by parallel slits cut in an aluminum foil, where the excitation coming from a flashlight can penetrate. This realization of super-resolution thermographic imaging demonstrates that blind structured illumination allows thermographic imaging without high degradation of the spatial resolution for deeper lying structures. The groundbreaking concept of super-resolution can be transferred from optics to diffusive imaging by defining a thermal point-spread-function, which gives the principle resolution limit for a certain signal-to-noise ratio, similar to the Abbe limit for a certain optical wavelength. In future work, the unknown illumination pattern could be the speckle pattern generated by a short laser pulse inside a light scattering sample or tissue. [ABSTRACT FROM AUTHOR]

Insulating low-frequency sound is a conventional challenge due to the high areal mass required by mass law. In this letter, we propose a smart acoustic metasurface consisting of an ultra-thin aluminum foil bonded with piezoelectric resonators. Numerical and experimental results show that the metasurface can break the conventional mass law of sound insulation by 30 dB in the low frequency regime (<1000 Hz), with an ultra-light areal mass density (<1.6 kg/m2) and an ultra-thin thickness (1000 times smaller than the operating wavelength). The underlying physical mechanism of such extraordinary sound insulation performance is attributed to the infinite effective dynamic mass density produced by the smart resonators. It is also demonstrated that the excellent sound insulation property can be conveniently tuned by simply adjusting the external circuits instead of modifying the structure of the metasurface. [ABSTRACT FROM AUTHOR]

We show that electron bunches in the 50-100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments. [ABSTRACT FROM AUTHOR]

Biocompatible composite coatings are produced from solution processable poly(vinylidene fluoride)/cyanoacrylate blends prepared in the presence of rosin and ZnO particle fillers, the latter for control of coating surface microstructure. Dispersions are spray coated and cured at 100 °C onto aluminum foils and fiberglass cloths suitable for tissue engineering applications. The elastic modulus of the composite films matches or exceeds that of polyethylene-based orthopedic implant materials. Contact angle measurements on coated fiberglass cloths reveal that wettability of hydrophobic coatings is maintained under strain for applied mechanical stress levels up to ∼15 kN/m2, whereas ultrahydrophobic coatings fail at ∼5 kN/m2. [ABSTRACT FROM AUTHOR]

The authors report flexible and low-voltage pentacene organic field-effect transistors (OFETs) constructed with an aluminum foil gate electrode, which was fabricated by the simple and low-cost roll-to-roll lamination process. Electropolishing the surface of laminated aluminum foil and spin coating it with an additional thin polymer film resulted in a gate dielectric surface with a root-mean-square roughness of about 0.85 nm. These pentacene OFETs with a poly(α-methylstyrene)/anodized Al2O3 dual-layered gate dielectric exhibit a mobility of 0.52 cm2/V s, an on-off ratio of 105, a subthreshold swing of 317 mV/decade, and little hysteresis when operating at -5 V. [ABSTRACT FROM AUTHOR]

Structural evolution of pyrochlore titanate Sm2Ti2O7 at high pressures was investigated by in situ Raman and x-ray diffraction methods. An intermediate phase was found at high pressures. The structure is a distorted pyrochlore, where anions are disordered after 40 GPa while the cations are still somewhat ordered up to 51 GPa. When the pyrochlore structure is severely distorted by external pressure, it transforms completely to an amorphous phase quenchable to room conditions. [ABSTRACT FROM AUTHOR]

We report on the first experimental investigation of the use of a magnetically accelerated foil-moving foil-as a vacuum opening switch. One megampere, 60% of the total current, was transferred to a low inductance path in 800 ns. [ABSTRACT FROM AUTHOR]

Validates the models used to describe positron stopping in aluminum foils mounted on glass backplates. Difference of the measured median penetration depth from values of the empirical power model; Disparity between the measured implantation profiles and analytic representation; Implications of the disparity for defect profiling analysis.

Gold and aluminum foils with nano-structured edges were investigated as electrodes for corona discharges in nitrogen and ambient air. Low onset voltages were observed due to the field enhancement near the edges of the foil. The lowest onset voltage was determined to be about 1.2 kV in ambient air and about 1.1 kV in nitrogen for a 5 mm inter-electrode spacing. This is significantly smaller than the values reported in the literature for sharp tips with similar electrode spacing. The foil-based electrode tips are extremely simple to produce, making them candidates for low-cost, low power consumption and easily available corona-discharge technology. [ABSTRACT FROM AUTHOR]