Evolving technologies for growing, imaging and analyzing 3D root system architecture of crop plants

A plant's ability to maintain or improve its yield under limiting conditions, such as nutrient deficiency or drought, can be strongly influenced by root system architecture (RSA), the three-dimensional distribution of the different root types in the soil. The ability to image, track and quantify these root system attributes in a dynamic fashion is a useful tool in assessing desirable genetic and physiological root traits. Recent advances in imaging technology and phenotyping software have resulted in substantive progress in describing and quantifying RSA. We have designed a hydroponic growth system which retains the three-dimensional RSA of the plant root system, while allowing for aeration, solution replenishment and the imposition of nutrient treatments, as well as high-quality imaging of the root system. The simplicity and flexibility of the system allows for modifications tailored to the RSA of different crop species and improved throughput. This paper details the recent improvements and innovations in our root growth and imaging system which allows for greater image sensitivity (detection of fine roots and other root details), higher efficiency, and a broad array of growing conditions for plants that more closely mimic those found under field conditions

New Methods Visualizing Mesostructured Materials

On the one hand this work intends to present new possibilities on how the combination of characterization methods can be used to gain information not available from the individual techniques. On the other hand discrete tomography - a relatively new method in materials science - is used to image real three-dimensional nano structures with a resolution of only a few nanometers. Visualization not only facilitates the interpretation of scientific results, but also aims at contributing to a better general understanding of nano technology

Two-Dimensional Photonic Crystals for Engineering Atom-Light Interactions

We present a two-dimensional (2D) photonic crystal system for interacting with cold cesium (Cs) atoms. The band structures of the 2D photonic crystals are predicted to produce unconventional atom-light interaction behaviors, including anisotropic emission, suppressed spontaneous decay and photon mediated atom-atom interactions controlled by the position of the atomic array relative to the photonic crystal. An optical conveyor technique is presented for continuously loading atoms into the desired trapping positions with optimal coupling to the photonic crystal. The device configuration also enables application of optical tweezers for controlled placement of atoms. Devices can be fabricated reliably from a 200nm silicon nitride device layer using a lithography-based process, producing predicted optical properties in transmission and reflection measurements. These 2D photonic crystal devices can be readily deployed to experiments for many-body physics with neutral atoms, and engineering of exotic quantum matter

Holoscopic 3D imaging and display technology: Camera/ processing/ display

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonHoloscopic 3D imaging “Integral imaging” was first proposed by Lippmann in 1908. It has become an attractive technique for creating full colour 3D scene that exists in space. It promotes a single camera aperture for recording spatial information of a real scene and it uses a regularly spaced microlens arrays to simulate the principle of Fly’s eye technique, which creates physical duplicates of light field “true 3D-imaging technique”. While stereoscopic and multiview 3D imaging systems which simulate human eye technique are widely available in the commercial market, holoscopic 3D imaging technology is still in the research phase. The aim of this research is to investigate spatial resolution of holoscopic 3D imaging and display technology, which includes holoscopic 3D camera, processing and display. Smart microlens array architecture is proposed that doubles spatial resolution of holoscopic 3D camera horizontally by trading horizontal and vertical resolutions. In particular, it overcomes unbalanced pixel aspect ratio of unidirectional holoscopic 3D images. In addition, omnidirectional holoscopic 3D computer graphics rendering techniques are proposed that simplify the rendering complexity and facilitate holoscopic 3D content generation. Holoscopic 3D image stitching algorithm is proposed that widens overall viewing angle of holoscopic 3D camera aperture and pre-processing of holoscopic 3D image filters are proposed for spatial data alignment and 3D image data processing. In addition, Dynamic hyperlinker tool is developed that offers interactive holoscopic 3D video content search-ability and browse-ability. Novel pixel mapping techniques are proposed that improves spatial resolution and visual definition in space. For instance, 4D-DSPM enhances 3D pixels per inch from 44 3D-PPIs to 176 3D-PPIs horizontally and achieves spatial resolution of 1365 × 384 3D-Pixels whereas the traditional spatial resolution is 341 × 1536 3D-Pixels. In addition distributed pixel mapping is proposed that improves quality of holoscopic 3D scene in space by creating RGB-colour channel elemental images

Untersuchung von Magnetostriktiven und Piezotronischen Mikrostrukturen und Materialien für biomagnetische Sensoren mittels Röntgenstrahlen

Detecting electric potential differences from the human physiology is an established technique in medical diagnosis, e.g., as electrocardiogram. It arises from a changing electrical polarization of living cells. Simultaneously, biomagnetism is induced and can be utilized for medical examinations, as well. Benefits in using magnetic signals are, no need for direct skin contact and an increased spatial resolution, e.g., for mapping brain activity, especially in combination with electrical examinations. But biomagnetic signals are very weak and, thus, highly sensitive devices are necessary. The development of small and easy to use biomagnetic sensors, with a sufficient sensitivity, is the goal of the Collaborative Research Centre 1261 - Magnetoelectric Sensors: From Composite Materials to Biomagnetic Diagnostics. This thesis was written as part of this collaboration, with the main focus on the investigation of crystalline structures and structure related properties of piezotronic and magnetostrictive materials by utilizing a selection of X-ray techniques, i.e., X-ray diffraction (XRD), X-ray reflectivity (XRR) and coherent X-ray diffraction imaging (CXDI). Piezotronics, realized by combining piezoelectricity and Schottky contacts in one structure, provides a promising path to enhance sensor sensitivity. A first study investigated the crystalline structure of three piezotronic ZnO rods, spatially resolved by scanning nano XRD and combined with electrical examinations of their Schottky contact properties. It is found that the crystalline quality has a clear impact on the electrical properties of the related Schottky contact, probably due to crystalline defects. A complementary transmission electron microscopy (TEM) and XRD study performed on hybride vapor phase epitaxy (HVPE) grown GaN showed a slight, photoelectrochemical etching related relaxion of strain originating from crystal growth. In a separate study, CXDI was utilized for three-dimensional visualization of strain in a gold coated ZnO rod, with spatial resolution below 30 nm. A distinct strain distribution was found inside the rod, denoted to depletion and screening effects occurring in bent piezotronic structures, and a high strain at the interface may be related to Schottky contact formation. This interface strain agrees with results obtained from TEM. A succeeding CXDI study was conducted on a ZnO rod coated with magnetostrictive FeCoSiB and the possibility for the investigation of the Schottky contacts electrical properties. It was found that FeCoSiB sputtered on ZnO results in an ohmic contact and that an external magnetic field causes a change of the electrical properties, probably due to a strain change, visualized by CXDI. In a fifth study, magnetostrictive FeCo/TiN multilayer structures were investigated by a combined TEM and XRD/XRR approach, showing a relaxation of the structure due to an annealing process and a cube-on-cube structure of the FeCo and TiN layers

Dissipative solitons in pattern-forming nonlinear optical systems : cavity solitons and feedback solitons

Many dissipative optical systems support patterns. Dissipative solitons are generally found where a pattern coexists with a stable unpatterned state. We consider such phenomena in driven optical cavities containing a nonlinear medium (cavity solitons) and rather similar phenomena (feedback solitons) where a driven nonlinear optical medium is in front of a single feedback mirror. The history, theory, experimental status, and potential application of such solitons is reviewed