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.

Optimal force control of a permanent magnet linear synchronous motor with multiple shuttles.

Using permanent magnet linear synchronous machines for transportation tasks offers a higher flexibility in production plants compared to conventional conveyor solutions. In this context, passive transportation devices (shuttles) with permanent magnets are commonly used. When multiple shuttles are operated in close vicinity, disturbances due to magnetic interaction can occur.

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.

Real-time optimal quantum control of mechanical motion at room temperature.

The ability to accurately control the dynamics of physical systems by measurement and feedback is a pillar of modern engineering. Today, the increasing demand for applied quantum technologies requires adaptation of this level of control to individual quantum systems. Achieving this in an optimal way is a challenging task that relies on both quantum-limited measurements and specifically tailored algorithms for state estimation and feedback.

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.

Signal reversal in Kelvin-probe force microscopy.

Kelvin-probe force microscopy is a measurement mode of atomic force microscopy, which is used to quantitatively map the electrical surface potential of a sample. Inadequate hardware and electronic design can lead to signal cross talk and, in consequence, false results. Here, we show that certain cross talk artifacts not only do manifest themselves in additional noise, reduced resolution, or an offset of the measured surface potential but can also lead to an inverted signal scale and, crucially, cannot be diagnosed with a known reference signal.

Water desorption in Kelvin-probe force microscopy: a generic model.

Nanoparticles or similar, nanoscale objects such as proteins or biological fibrils usually have to be deposited from aqueous suspension onto a solid support surface for further characterization by atomic force microscopy (AFM) and related methods such as Kelvin-probe force microscopy (KFM). Here we show, on the examples of functionalized nanoparticles and collagen fibrils, that water desorption after sample preparation affects their electrostatic potential determined by KFM in a predictable manner. We explain this effect with a simple, analytical model based on the capacitance of the partially dielectric-filled tip-sample system.

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.

Active damping by Q-control for fast force-distance curve measurements in atomic force microscopy.

This paper investigates the benefit of active damping by an analog Q-control circuit for measuring fast force-distance curves in atomic force microscopy. By active damping of the cantilever oscillation after snap-off, the down-ring time-constant is reduced significantly from 385 μs to 23 μs. Experimental results demonstrate that the number of force-distance curves per second can be increased by a factor of more than 30.

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.

Learning of perceptual grouping for object segmentation on RGB-D data.

Object segmentation of unknown objects with arbitrary shape in cluttered scenes is an ambitious goal in computer vision and became a great impulse with the introduction of cheap and powerful RGB-D sensors. We introduce a framework for segmenting RGB-D images where data is processed in a hierarchical fashion. After pre-clustering on pixel level parametric surface patches are estimated.