| Cystoliths are amorphous calcium carbonate bodies that form in the leaves of some plant families. Cystoliths are regularly distributed in the epidermis and protrude into the photosynthetic tissue, the mesophyll. The photosynthetic pigments generate a steep light gradient in the leaf. Under most illumination regimes the outer mesophyll is light saturated, thus the photosynthetic apparatus is kinetically unable to use the excess light for photochemistry. Here we use micro-scale modulated fluorometry to demonstrate that light scattered by the cystoliths is distributed from the photosynthetically inefficient upper tissue to the efficient, but light deprived, lower tissue. The results prove that the presence of light scatterers reduces the steep light gradient, thus enabling the leaf to use the incoming light flux more efficiently. MicroCT and electron microscopy confirm that the spatial distribution of the minerals is compatible with their optical function. During the study we encountered large calcium oxalate druses in the same anatomical location as the cystoliths. These druses proved to have similar light scattering functions as the cystoliths. This study shows that certain minerals in the leaves of different plants distribute the light flux more evenly inside the leaf.Leaf minerals function as internal light scatterersinside leaves. They transfer light from the saturated upper tissue into the light deprived lower tissue. This eases the steep light gradient inside the leaf and improves photosynthetic efficiency on the tissue scale. |
2012-1-31 06:30
Certain Biominerals in Leaves Function as Light Scatterers
Assaf Gal | RSS
2012-1-31 06:30
Microstructuring of Polypyrrole by Maskless Direct Femtosecond Laser Ablation
| Ultrafast laser micromachining was optimized for microstructuringpolypyrrole as a facile new approach towards tailoring electrochemical and mechanical responses desirable for microactuator, sensors, neural probing, and nerve conduit applications. Laser perforation of high-density and high aspect ratio through-holes generated greater than 5-fold increase in surface area. The flexible machining technique offers micron-size resolution and fast prototyping capability for optimizing properties and opening new directions for polypyrrole-based devices. |
Kenneth K.C. Lee | RSS
2012-1-31 03:10
A Polyferroplatinyne Precursor for the Rapid Fabrication of L10-FePt-type Bit Patterned Media by Nanoimprint Lithography
| A polyferroplatinyne polymer can be patterned on the surface of Si wafer in ordered nanoline or nanodot shapes with PDMS molds through nanoimprint lithography (NIL), and subsequent thermal treatment gives rise to the nanopatterned arrays of L10-FePt nanoparticles with the same periodicities. The method offers excellent potential to be utilized in the simple and rapid fabrication of bit patterned media for magnetic data recording. |
Qingchen Dong | RSS
2012-1-31 03:10
Direct Transfer Patterning of Electrically Small Antennas onto Three-Dimensionally Contoured Substrates
| A direct transfer patterningprocess is presented that allows metallic patterns to be stamped onto a contoured substrate. This process was used to make some of the most efficient electrically small antennas to date, while maintaining bandwidths approaching the physical limit. |
Carl Pfeiffer | RSS
2012-1-31 02:51
Homoepitaxial Growth of Single Crystal Diamond Membranes for Quantum Information Processing
| Homoepitaxial growth of single crystal diamond membranes is demonstrated employing a microwave plasma chemical vapor deposition technique. The membranes possess excellent structural, optical, and spin properties, which make them suitable for fabrication of optical microcavities for applications in quantum information processing, photonics, spintronics, and sensing. |
Igor Aharonovich | RSS
2012-1-30 06:40
Silicon Filaments in Silicon Oxide for Next-Generation Photovoltaics
| Nanometer wide silicon filaments embedded in an amorphous silicon oxide matrix are grown at low temperatures over a large area. The optical and electrical properties of these mixed-phase nanomaterials can be tuned independently, allowing for advanced light management in high efficiency thin-film silicon solar cells and for band-gap tuning via quantum confinement in third-generation photovoltaics. |
Peter Cuony | RSS
2012-1-30 06:40
Real-Time Ion-Flux Imaging in the Growth of Micrometer-Scale Structures and Membranes
| Real-time ion flux imaging: an ion-sensitive field-effect transistor (ISFET) array is coupled with optical microscopy to image the growth of, and ion flux through, micrometer-scale tubes and membranes built from polyoxometalate clusters. The correlation between the optical and ionic imaging data is excellent, showcasing the use of ISFET arrays for high-resolution spatial and temporal mapping of ionic movements. |
Balazs Nemeth | RSS
2012-1-30 03:11
Aqueous Dye-Sensitized Solar Cell Electrolytes Based on the Ferricyanide–Ferrocyanide Redox Couple
| Solar energy conversion efficiencies of over 4% have been achieved in DSCs constructed with aqueous electrolytes based on the ferricyanide–ferrocyanide redox couple, thereby avoiding the use of expensive, flammable and toxic solvents. This paradigm shift was made possible by the use of a hydrophobic organic carbazole dye. |
Torben Daeneke | RSS
2012-1-30 03:10
Enhanced Electrochromism in Gyroid-Structured Vanadium Pentoxide
| Manufacturing V2O5 in a 3D periodic highly interconnected gyroidstructure on the 10 nm length scale is shown to lead to a significant electrochromic performance enhancement. The structured devices surpass previous inorganic electrochromic materials in all relevant parameters: the switching speed, coloration contrast, and composite coloration efficiency. In particular, the 85 ms switching speed lies within a factor of two of video rate. Enhanced ion intercalation into the gyroid morphology can be extended to other transition-metal oxides and is therefore promising for lithium ion batteries, supercapacitors, and sensors. |
Maik R. J. Scherer | RSS
2012-1-27 11:11
Total Syntheses of All the Amathaspiramides
| Six in one blow: Total syntheses of all the amathaspiramide alkaloids have been accomplished. Rapid construction of the diazaspiro[3.3]nonane core combined with regio- and diastereoselective reduction of the cyclic imide moiety with DIBAL established the route to the common structural motif. The late-stage reduction of the lactam to an imine functionality mediated by Schwartz’s reagent was the key to the streamlined syntheses. |
Koji Chiyoda | RSS
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