Antibacterial Optimization of Highly Deformed Titanium Alloys for Spinal Implants

The goal of the work was to develop materials dedicated to spine surgery that minimized the potential for infection originating from the transfer of bacteria during long surgeries. The bacteria form biofilms, causing implant loosening, pain and finally, a risk of paralysis for patients. Our strategy focused both on improvement of antibacterial properties against bacteria adhesion and on wear and corrosion resistance of tools for spine surgery. Further, a ~35% decrease in implant and tool dimensions was expected by introducing ultrahigh-strength titanium alloys for less-invasive surgeries. The tested materials, in the form of thin, multi-layered coatings, showed nanocrystalline microstructures. Performed direct-cytotoxicity studies (including lactate dehydrogenase activity measurement) showed that there was a low probability of adverse effects on surrounding SAOS-2 (Homo sapiens bone osteosarcoma) cells. The microbiological studies (e.g., ISO 22196 contact tests) showed that implanting Ag nanoparticles into Ti/Ti_xN coatings inhibited the growth of E. coli and S. aureus cells and reduced their adhesion to the material surface. These findings suggest that Ag-nanoparticles present in implant coatings may potentially minimize infection risk and lower inherent stress.     

Analog integrating detection technique for pulsed muon beams

A new analog integrating detection technique for time resolvedSR measurements at high intensity pulsed muon beams has been developed. Data acquisition is realized by digitizing the integrated anode signal for each burst by means of a fast transient recorder. Details of setup and performance are described.     

Determination of isoniazid and hydrazine by capillary electrophoresis with amperometric detection at a Pt-particle modified carbon fiber microelectrode

Capillary electrpphoresis (CE)/electrochemical detection (EC) for the simultane-ous determination of hydrazine and isoniazid has been developed.The electrochemical method uses a novel modified electrode dispersed with ultrafine platinum particles on the surface of a 30μm carbon fiber microelectrode.The unique characteristic of the Pt-particles modified carbon fiber microelectrode is its excellent stability.The current measurement for hydrazine is more sensitive than that of isoniazid.Selective determination of trace amount of free hydrazine in isoniazid and its formulation can be achieved at applied potential of 0.5V.     

Analogue detection technique

A technique to handle the high data rates of a pulsed beam as available at KEK and RAL is described. Different detector concepts, which would also allow to increase the initial asymmetry have been tested and are presented.This work was supported by the German Federal Minister for Research and Technology (Bundesminister für Forschung und Technologie [BMFT]) under Contract Nr. 03KA2-TUM-4.     

Influence of elastic strain onμ + SR in α-iron single crystalsSR in α-iron single crystals

The spin-precession frequencies and the transverse spin relaxation rates of positive mouns (μ ⁺) have been measured on two elastically strained α-Fe single crystal platelets as well as on an unstrained reference α-Fe crystal at temperatures down to 2.7 K in applied magnetic field 0≤B _appl≤3 T. The drastic effects of the strains may be qualitatively understood in terms of their influence on both the magnetic domain structure and theμ ⁺ energies at the various interstitial sites. This leads to the conclusion that at low temperaturesμ ⁺ in α-Fe occupy configurations related to octahedral interstitials with dipolar fieldB _dip=0.70 T.     

Coherent two-photon absorption spectroscopy of the Raman-active KGd(WO4)2 crystal

We report on the systematic open-aperture Z-scan characterization of the two-photon absorption properties in one of the most efficient solid-state Raman frequency shifters, the crystal potassium gadolinium tungstate [KGd(WO4)2]. The two-photon absorption coefficient was determined in the 370-600-nm wavelength range, with the highest value found to be approximately 1.9 cm/GW at 370 nm. Nonlinear losses are crucial in determining the conversion efficiency of the stimulated Raman scattering process when it is excited with ultrashort laser pulses with photon energy exceeding half of the bandgap. In addition, the results were analyzed within the context of a simple two-parabolic-band theoretical model to yield an effective bandgap energy value for the crystal.     

Efficient Raman shifting of high-energy picosecond pulses into the eye-safe 1.5-microm spectral region by use of a KGd(WO4)2 crystal

We report an efficient transient stimulated Raman conversion of high-energy picosecond pulses at 1350 nm into the eye-safe 1500-nm wavelength range by use of a KGd(WO4)2 crystal. The conversion efficiency into either 1503- or 1537-nm radiation (767- or 901-cm(-1) Raman modes, respectively) is measured to be approximately 10% in a single-pass configuration. The transient Raman gain coefficient is found to be approximately 0.8 cm/GW. Simultaneous generation of multiple Raman lines is also observed.     

A study of ϱ0 and f0 production in 4 GEV/cπ+d interactions

The production of ?⁰ and f⁰ mesons has been studied using a sample of 15485 fits to the reaction π⁺d → p_spπ⁺π^? at 4 GeV/c. Results are presented on the spin structure and production mechanisms of these resonances. An Estabrooks and Martin analysis has been carried out in the ?⁰ region, giving results similar to those obtained in their analysis of 17.2 GeV/c data. Natural parity exchange is less important at our momentum, however. In the case of f⁰ production, we find evidence for the presence of s-, p- and d-waves in the π π system. Averaging all events in the f⁰ peak, the s- and d-waves are found to be close in phase. The f⁰ production mechanism has been investigated using a positivity analysis of the complete J = 0, 1, 2 density matrix, and the same general features are observed as are seen in ?⁰ production. However, the unnatural parity exchange component is found to be even more dominant in f⁰ production than in ?⁰ production. Our results are compared with the predictions of various models.