New software for three-dimensional visualization and calculation of volume of living cells.

We investigated the physical properties of head and neck cancer cells to develop new cell-selective treatment strategies for squamous cell carcinoma. For better characterization and subsequent differentiation of cancerous and healthy cells, we developed MATLAB-based software to analyze image stacks obtained using a confocal laser-scanning microscope. A confocal laser-scanning microscope was used for three-dimensional (3-D) imaging of a cell line from the head and neck area. The volume of cell organelles of interest was calculated using our newly developed software. Our software enables 3-D visualization and volume calculation as well as data analysis associated with cell morphology. Using filter and semi-automatic segmentation algorithms, our software recognizes individual cell organelles in each slice of an image stack. It matches the corresponding cell cross section areas to produce a 3-D image and to determine the volume of the imaged organelles. We calculated the volume of the nucleus, actin filaments and microtubules in relation to total cell volume. Our software enables 3-D visualization and calculation of organelle volume, which improves cell characterization and comparison of healthy and cancerous cell lines. Differences between cell lines can be observed in detail and used to develop new cancer treatment strategies.

Navigation aid for blind persons by visual-to-auditory sensory substitution: A pilot study.

PURPOSE: In this study, we investigate to what degree augmented reality technology can be used to create and evaluate a visual-to-auditory sensory substitution device to improve the performance of blind persons in navigation and recognition tasks. METHODS: A sensory substitution algorithm that translates 3D visual information into audio feedback was designed. This algorithm was integrated in an augmented reality based mobile phone application. Using the mobile device as sensory substitution device, a study with blind participants (n = 7) was performed. The participants navigated through pseudo-randomized obstacle courses using either the sensory substitution device, a white cane or a combination of both. In a second task, virtual 3D objects and structures had to be identified by the participants using the same sensory substitution device. RESULTS: The realized application for mobile devices enabled participants to complete the navigation and object recognition tasks in an experimental environment already within the first trials without previous training. This demonstrates the general feasibility and low entry barrier of the designed sensory substitution algorithm. In direct comparison to the white cane, within the study duration of ten hours the sensory substitution device did not offer a statistically significant improvement in navigation.

Structure, morphology, and magnetic properties of Fe nanoparticles deposited onto single-crystalline surfaces.

BACKGROUND: Magnetic nanostructures and nanoparticles often show novel magnetic phenomena not known from the respective bulk materials. In the past, several methods to prepare such structures have been developed - ranging from wet chemistry-based to physical-based methods such as self-organization or cluster growth. The preparation method has a significant influence on the resulting properties of the generated nanostructures. Taking chemical approaches, this influence may arise from the chemical environment, reaction kinetics and the preparation route. Taking physical approaches, the thermodynamics and the kinetics of the growth mode or - when depositing preformed clusters/nanoparticles on a surface - the landing kinetics and subsequent relaxation processes have a strong impact and thus need to be considered when attempting to control magnetic and structural properties of supported clusters or nanoparticles. RESULTS: In this contribution we focus on mass-filtered Fe nanoparticles in a size range from 4 nm to 10 nm that are generated in a cluster source and subsequently deposited onto two single crystalline substrates: fcc Ni(111)/W(110) and bcc W(110). We use a combined approach of X-ray magnetic circular dichroism (XMCD), reflection high energy electron diffraction (RHEED) and scanning tunneling microscopy (STM) to shed light on the complex and size-dependent relation between magnetic properties, crystallographic structure, orientation and morphology. In particular XMCD reveals that Fe particles on Ni(111)/W(110) have a significantly lower (higher) magnetic spin (orbital) moment compared to bulk iron. The reduced spin moments are attributed to the random particle orientation being confirmed by RHEED together with a competition of magnetic exchange energy at the interface and magnetic anisotropy energy in the particles. The RHEED data also show that the Fe particles on W(110) - despite of the large lattice mismatch between iron and tungsten - are not strained. Thus, strain is most likely not the origin of the enhanced orbital moments as supposed before. Moreover, RHEED uncovers the existence of a spontaneous process for epitaxial alignment of particles below a critical size of about 4 nm. STM basically confirms the shape conservation of the larger particles but shows first indications for an unexpected reshaping occurring at the onset of self-alignment. CONCLUSION: The magnetic and structural properties of nanoparticles are strongly affected by the deposition kinetics even when soft landing conditions are provided. The orientation of the deposited particles and thus their interface with the substrate strongly depend on the particle size with consequences regarding particularly the magnetic behavior. Spontaneous and epitaxial self-alignment can occur below a certain critical size. This may enable the obtainment of samples with controlled, uniform interfaces and crystallographic orientations even in a random deposition process. However, such a reorientation process might be accompanied by a complex reshaping of the particles.