Methylglyoxal alters collagen fibril nanostiffness and surface potential.

Collagen fibrils are fundamental to the mechanical strength and function of biological tissues. However, they are susceptible to changes from non-enzymatic glycation, resulting in the formation of advanced glycation end-products (AGEs) that are not reversible. AGEs accumulate with aging and disease and can adversely impact tissue mechanics and cell-ECM interactions.

High-speed telescope autofocus for UAV detection and tracking.

This paper presents the analysis, implementation and experimental evaluation of a high-speed automatic focus module for a telescope-based UAV detection and tracking system. An existing optical drone detection system consisting of two telescopes and deep learning-based object detection is supplemented by suitable linear stages and passive focus algorithms to enable fast automatic focus adjustment. Field tests with the proposed system demonstrate that UAVs flying at speeds of up to 24 m/s towards the system are successfully tracked and kept in focus from more than 4500 m down to 150 m.

Reconstructing highly divergent wavefronts from sparse measurements.

The paper presents a concept for the sparse measurement and reconstruction of highly divergent wavefronts enabling measurements at high throughputs and beyond the dynamic range of the wavefront sensor. In the proposed concept, a direct measurement of the wavefront is carried out, where a few segments of the wavefront are measured with Shack-Hartmann sensors (SHSs). In total about 1% of the wavefront is measured and used for the reconstruction of the entire wavefront, which makes the concept suitable for applications where low measurement times are needed.

Fast modal reconstruction of large plane wavefronts from sparse measurements using Shack-Hartmann sensors.

A concept for the fast measurement and reconstruction of optical wavefronts using Shack-Hartmann sensors (SHSs) is presented. For wavefronts with a diameter at the scale of several tens of millimeters, hundreds of measurements with an SHS may be necessary to cover the wavefront. In the proposed concept, a few SHSs are used to measure about 2% of the entire wavefront, providing sufficient measurement data for its successful reconstruction.

Camera-guided real-time laser ranging for multi-UAV distance measurement.

This paper presents the design and implementation of a scalable laser ranger finder (LRF)-based prototype system, which enables distance measurement and precise localization of multiple unmanned aerial vehicles (UAVs) in real-time. The system consists of a telescope and camera as the image acquisition components, supplemented by an LRF and a fast steering mirror (FSM) to obtain the distance measurement. By combining the optical path of the camera and the LRF through a dichroic mirror, the LRF is accurately aligned by the FSM based on the angular position of a UAV within the camera field of view.

Improving the precision of parallel registration by incorporating a priori information.

This paper presents an algorithm for the precise registration of optical wavefronts. A wavefront exceeding the spatial or dynamic measurement range of a wavefront sensor, e.g.

AC Kelvin Probe Force Microscopy Enables Charge Mapping in Water.

Mapping charged chemical groups at the solid-liquid interface is important in many areas, ranging from colloidal systems to biomolecular interactions. However, classical methods to measure surface charges either lack spatial resolution or─like Kelvin-probe force microscopy (KPFM)─cannot be applied in aqueous solutions because a DC bias voltage is used. Here, we show that using AC Kelvin probe force microscopy (AC-KPFM), in which the DC bias is replaced with an AC voltage of sufficiently high frequency, the surface potential of spatially fixated, charged surface groups can be mapped in aqueous solution.

Instrument for tensile testing of individual collagen fibrils with facile sample coupling and uncoupling.

Collagen is the major structural protein in human bodies constituting about 30% of the entire protein mass. Through a self-assembly process, triple helical collagen molecules assemble into high aspect-ratio fibers of tens to hundreds of nanometer diameter, known as collagen fibrils (CFs). In the last decade, several methods for tensile testing these CFs emerged.

Iterative parallel registration of strongly misaligned wavefront segments.

The paper presents an algorithm for the precise registration of multiple wavefront segments containing large misalignment and phase differences. The measurement of a wavefront with huge dynamics or a large aperture size can be carried out in multiple Shack-Hartmann sensor measurements of segments of the wavefront. The registration algorithm is flexible with respect to the shape of the wavefront and can reconstruct a plane as well as divergent wavefronts, making it suitable for freeform wavefronts.

Adaptive Lissajous scanning pattern design by phase modulation.

This paper proposes a phase modulation method for Lissajous scanning systems, which provides adaptive scan pattern design without changing the frame rate or the field of view. Based on a rigorous analysis of Lissajous scanning, phase modulation constrains and a method for pixel calculation are derived. An accurate and simple metric for resolution calculation is proposed based on the area spanned by neighboring pixels and used for scan pattern optimization also considering the scanner dynamics.

Compact scanning confocal chromatic sensor enabling precision 3-D measurements.

This paper proposes a compact and lightweight scanning confocal chromatic sensor (SCCS) for robot-based precision three-dimensional (3-D) surface measurement applications. The integrated system design includes a 2-D fast steering mirror (FSM) to manipulate the optical path of a high precision 1-D confocal chromatic sensor (CCS). A data-driven calibration procedure is used to accurately combine the FSM deflection angles and the correspondingly measured distances to the sample surface in order to obtain a correctly reconstructed 3-D image.

Fast, precise, and shape-flexible registration of wavefronts.

A fast and precise algorithm for wavefront reconstruction by the registration of wavefront segments is presented. If the wavefront exceeds the sensor aperture or the dynamic range of the sensor, a Shack-Hartmann sensor can measure only segments of an optical wavefront. The algorithm registers the wavefront segments in parallel, where they are simultaneously transformed to minimize their overlap mismatch for precise reconstruction of the entire wavefront.

Robust wavefront segment registration based on a parallel approach.

This paper presents a robust registration algorithm for wavefront reconstruction from multiple partial measurements. Wavefronts exceeding the dynamic range or size of the Shack-Hartmann sensor can be measured as a set of segments. The wavefront is reconstructed by parallel registration of these wavefront segments, enabling compensation for sensor misalignment as well as for phase differences.

High-speed scanning chromatic confocal sensor for 3-D imaging with modeling-free learning control.

This paper presents a scanning system that integrates a chromatic confocal displacement sensor for topography measurement of a surface. To take an advantage of its compactness and reliability, an off-the-shelf chromatic confocal displacement sensor is integrated. Instead of moving the sensor, a galvanometer scanner reflects the optical point to increase the scan speed, and fast and accurate scanning motion is realized by learning without a model.

Confocal chromatic sensor with an actively tilted lens for 3D measurement.

Confocal chromatic displacement sensors are versatile and precise sensors for measuring the distance to a single point. In order to obtain a 3D measurement device, this paper presents an integrated scanning sensor design that employs a tilting lens mechanism for manipulating the light path of the sensor. The optical implications of the design are analytically modeled and simulated.

Glycation changes molecular organization and charge distribution in type I collagen fibrils.

Collagen fibrils are central to the molecular organization of the extracellular matrix (ECM) and to defining the cellular microenvironment. Glycation of collagen fibrils is known to impact on cell adhesion and migration in the context of cancer and in model studies, glycation of collagen molecules has been shown to affect the binding of other ECM components to collagen. Here we use TEM to show that ribose-5-phosphate (R5P) glycation of collagen fibrils - potentially important in the microenvironment of actively dividing cells, such as cancer cells - disrupts the longitudinal ordering of the molecules in collagen fibrils and, using KFM and FLiM, that R5P-glycated collagen fibrils have a more negative surface charge than unglycated fibrils.

Optical scanning of laser line sensors for 3D imaging.

In scanning laser triangulation sensors for 3D imaging, the achievable throughput is strongly limited by the moving mass. By realizing an optical scanning approach rather than repositioning the entire sensor, this limitation could be reduced, leading to a reduced measurement time. This work presents sensor system geometries in which only the optical path of a line triangulation sensor is manipulated by a tip-tilt mirror.

Evaluation of surface charge shift of collagen fibrils exposed to glutaraldehyde.

Collagen fibrils are a major component of the extracellular matrix. They form nanometer-scale "cables" acting as a scaffold for cells in animal tissues and are widely used in tissue-engineering. Besides controlling their structure and mechanical properties, it is crucial to have information of their surface charge, as this affects how cells attach to the scaffold.

Atomic force microscopy capable of vibration isolation with low-stiffness Z-axis actuation.

For high-resolution imaging without bulky external vibration isolation, this paper presents an atomic force microscope (AFM) capable of vibration isolation with its internal Z-axis (vertical) actuators moving the AFM probe. Lorentz actuators (voice coil actuators) are used for the Z-axis actuation, and flexures guiding the motion are designed to have a low stiffness between the mover and the base. The low stiffness enables a large Z-axis actuation of more than 700 µm and mechanically isolates the probe from floor vibrations at high frequencies.

High bandwidth deflection readout for atomic force microscopes.

This contribution presents the systematic design of a high bandwidth deflection readout mechanism for atomic force microscopes. The widely used optical beam deflection method is revised by adding a focusing lens between the cantilever and the quadrant photodetector (QPD). This allows the utilization of QPDs with a small active area resulting in an increased detection bandwidth due to the reduced junction capacitance.

Fluorous iminoalditols: a new family of glycosidase inhibitors and pharmacological chaperones.

A collection of new reversible glycosidase inhibitors of the iminoalditol type featuring N-substituents containing perfluorinated regions has been prepared for evaluation of physicochemical, biochemical and diagnostic properties. The vast variety of feasible oligofluoro moieties allows for modular approaches to customised structures according to the intended applications, which are influenced by the fluorine content as well as the distance of the fluorous moiety from the ring nitrogen. The first examples, in particular in the D-galacto series, exhibited excellent inhibitory activities.

Synthesis and biological evaluation of novel biotin-iminoalditol conjugates.

Biotin-iminosugar conjugates of different configuration such as D-gluco, D-galacto, L-ido as well as a furanoid representative in the D-manno configuration have been synthesised and exhibit powerful inhibition of beta-glucosidase from Agrobacterium sp. with K(i) values in the range of the respective parent compounds. Such molecular probes have potential for activity-based protein profiling taking advantage of the biotin-(strept)avidin interaction.

Synthesis of lipophilic 1-deoxygalactonojirimycin derivatives as D-galactosidase inhibitors.

N-Alkylation at the ring nitrogen of the D-galactosidase inhibitor 1-deoxygalactonojirimycin with a functionalised C ₆alkyl chain followed by modification with different aromatic substituents provided lipophilic 1-deoxygalactonojirimycin derivatives which exhibit inhibitory properties against β-glycosidases from E. coli and Agrobacterium sp. as well as green coffee bean α-galactosidase.

DLHex-DGJ, a novel derivative of 1-deoxygalactonojirimycin with pharmacological chaperone activity in human G(M1)-gangliosidosis fibroblasts.

G(M1)-gangliosidosis (GM1) and Morquio B disease (MBD) are rare lysosomal storage disorders caused by mutations in the gene GLB1. Its main gene product, human acid beta-galactosidase (beta-Gal) degrades two functionally important molecules, G(M1)-ganglioside and keratan sulfate in brain and connective tissues, respectively. While GM1 is a severe, phenotypically heterogenous neurodegenerative disorder, MBD is a systemic bone disease without effects on the central nervous system.

2-Acetamino-1,2-dideoxynojirimycin-lysine hybrids as hexosaminidase inhibitors.

Cyclisation by double reductive amination of 2-acetamino-2-deoxy-D-xylo-hexos-5-ulose with N-2 protected L-lysine derivatives provided 2-acetamino-1,2-dideoxynojirimycin derivatives without any observable epimer formation at C-5. Modifications on the lysine moiety gave access to lipophilic derivatives that exhibited improved hexosaminidase inhibitory activities.