TiO2 thin films were deposited on the orthopedic implant material polyetheretherketone (PEEK) by plasma enhanced atomic layer deposition (PEALD) and characterized for their ability to enhance the osseointegrative properties. PEALD was chosen for film deposition to circumvent drawbacks present in line-of-sight deposition techniques, which require technically complex setups for a homogeneous coating thickness. Film conformality was analyzed on silicon 3D test structures and PEEK with micron-scale surface roughness. Wettability and surface energy were determined through contact angle measurements; film roughness and crystallinity were determined by atomic force microscopy and X-ray diffraction, respectively. Adhesion properties of TiO2 on PEEK were determined with tensile strength tests. Cell tests were performed with the mouse mesenchymal tumor stem cell line ST-2. TiO2-coated PEEK disks were used as substrates for cell proliferation tests and long-term differentiation tests. After 28 days of cultivation, a mineralized bone matrix was observed. Furthermore, the collagen I and osteocalcin content were determined. The results reveal that the osteogenic properties of the TiO2 thin film are comparable to those of hydroxyapatite, and thus bioactive properties of PEEK implants are improved by TiO2 thin films deposited with PEALD.

Optical half-wave microresonators enable to control the optical mode density around a quantum system and thus to modify the temporal emission properties. If the coupling rate exceeds the damping rate, strong coupling between a microresonator and a quantum system can be achieved, leading to a coherent energy exchange and the creation of new hybrid modes. Here, we investigate strong coupling between two adjacent /2 Fabry-Pérot microresonators, where the resonance of one microresonator can be actively tuned across the resonance of the other microresonator. The transmission spectra of the coupled microresonators show a clear anticrossing behavior, which proves that the two cavity modes are strongly coupled. Additionally, we can vary the coupling rate by changing the resonator geometry and thereby investigate the basic principles of strong coupling with a well-defined model system. Finally, we will show that such a coupled system can theoretically be modelled by coupled damped harmonic oscillators.Optical /2 microresonators are structures that confine light to volumes with dimensions on the order of a wavelength and enable to control and study light-matter interaction. The interaction between a quantum system and an optical field confined in a microresonator can be divided into the weak and strong coupling regime. In the weak coupling regime, the respective decay rates are larger than the coupling rate between the quantum system and the microresonator. In this case, the spontaneous emission rate of the quantum system is altered with respect to the free space, a phenomenon known as Purcell effect [1]. To reach the strong coupling regime, the coupling strength between the optical field in the resonator and the quantum system must be considerably larger than their respective decay rates. This leads to new hybrid polaritonic states [2], which have an energy difference proportional to the coupling strength. The spectral signature is a splitting of the absorption or transmission spectrum into two polaritonic modes, referred to as Rabi splitting [3]. When the cavity resonance is tuned over the eigenfrequency of the quantum system, anticrossing is observed in the dispersive behavior of the polaritonic modes [4]. The first observation of strong coupling between electromagnetic fields and a quantum system has been shown in the form of interaction between Rydberg atoms and a high Q microwave cavity at cryogenic temperatures [5]. Since then, many different optical experiments showing strong light matter coupling have been accomplished using metal or dielectric cavities [4,6-11], photonic crystals [12], micropillars [13] or microdisks [14] that couple with quantum dots [12][13][14], organic semiconductors [15] or J-aggregates [16]. Strong coupling has been shown for molecular systems from ensembles down to single molecules that couple to cavity fields, as well as to plasmonic modes [17][18][19] with sub wavelength dimensions. Today, strong coupling with plasmonic modes at ambient conditions has been shown even for single molecules...

A facile method is described to prepare micron partly hollow dumbbell silica particles in a single step. The obtained particles consist of a large dense part and a small hollow lobe. The spherical dense core as well as the hollow lobe are covered by mesoporous channels. In the case of the smaller lobe these channels are responsible for the permeability of the shell which was demonstrated by confocal imaging and spectroscopy.

Turbidity sensing is very common in the control of drinking water. Furthermore, turbidity measurements are applied in the chemical (e.g., process monitoring), pharmaceutical (e.g., drug discovery), and food industries (e.g., the filtration of wine and beer). The most common measurement technique is nephelometric turbidimetry. A nephelometer is a device for measuring the amount of scattered light of suspended particles in a liquid by using a light source and a light detector orientated in 90° to each other. Commercially available nephelometers cost usually—depending on the measurable range, reliability, and precision—thousands of euros. In contrast, our new developed GRIN-lens-based nephelometer, called GRINephy, combines low costs with excellent reproducibility and precision, even at very low turbidity levels, which is achieved by its ability to rotate the sample. Thereby, many cuvette positions can be measured, which results in a more precise average value for the turbidity calculated by an algorithm, which also eliminates errors caused by scratches and contaminations on the cuvettes. With our compact and cheap Arduino-based sensor, we are able to measure in the range of 0.1–1000 NTU and confirm the ISO 7027-1:2016 for low turbidity values.