In vitro response of THP-1 derived macrophages to antimicrobially effective PHMB-coated Ti6Al4V alloy implant material with and without contamination with S. epidermidis and P. aeruginosa

Paula Zwicker,Thomas Schmidt,Melanie Hornschuh,Holger Lode,Axel Kramer,Gerald Müller 한국생체재료학회 2022 생체재료학회지 Vol.26 No.1

Aim: Periprosthetic joint infections are a devastating complication after arthroplasty, leading to rejection of the prosthesis. The prevention of septic loosening may be possible by an antimicrobial coating of the implant surface. Poly (hexamethylene) biguanide hydrochloride [PHMB] seems to be a suitable antiseptic agent for this purpose since previous studies revealed a low cytotoxicity and a long-lasting microbicidal effect of Ti6Al4V alloy coated with PHMB. To preclude an excessive activation of the immune system, possible inflammatory effects on macrophages upon contact with PHMB-coated surfaces alone and after killing of S. epidermidis and P. aeruginosa are analyzed. Methods: THP-1 monocytes were differentiated to M0 macrophages by phorbol 12-myristate 13-acetate and seeded onto Ti6Al4V surfaces coated with various amounts of PHMB. Next to microscopic immunofluorescence analysis of labeled macrophages after adhesion on the coated surface, measurement of intracellular reactive oxygen species and analysis of cytokine secretion at different time points without and with previous bacterial contamination were conducted. Results: No influence on morphology of macrophages and only slight increases in iROS generation were detected. The cytokine secretion pattern depends on the surface treatment procedure and the amount of adsorbed PHMB. The PHMB coating resulted in a high reduction of viable bacteria, resulting in no significant differences in cytokine secretion as reaction to coated surfaces with and without bacterial burden. Conclusion: Ti6Al4V specimens after alkaline treatment followed by coating with 5–7 μg PHMB and specimens treated with H2O2 before PHMB-coating (4 μg) had the smallest influence on the macrophage phienotype and thus are considered as the surface with the best cytocompatibility to macrophages tested in the present study.

A new active vibration control method on a ladder of turntable ladders

Van Tinh Nguyen,Thorsten Schmidt,Thomas Leonhardt 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6

Our previous study showed the effect of pre-tension onto oscillation at the top of a ladder in raising and lowering processes on turntable ladders when steel wire ropes are added to ladder handrails. However, the oscillation was not switched off quickly. To quickly extinguish oscillation, we use steel ropes and a hydraulic system that is available on the truck to control the vibration. Based on the available multibody dynamic system and motion equation of the ladder, the group minimizes the number of variables in the motion equation and linearizes it. Thereafter, the vibration of the system is controlled and simulated by Matlab-Simulink software. This study presents a new method to control the ladder vibration on the turntable ladder.

Effect of pre-tensioned loads to vibration at the ladder tip in raising and lowering processes on a turntable ladder

Van Tinh Nguyen,Thorsten Schmidt,Thomas Leonhardt 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.5

A turntable ladder is an indispensable vehicle in fire and rescue work. Vibration on the top of the ladder is considerable when the ladder set is maximally extended. It induces the discomfort and unsafety for beings in the rescue cage. Aiming at the reduction of the vibration, in this study, one additional steel wire rope is assumedly added into each handrail of the ladder set. The steel wire ropes are suggested to be pre-tensioned before the turntable ladder works. This study is based on an available ladder set structure which includes three ladder sections with different area moments of inertia. Additionally, a ladder structure model is established as a multibody system dynamic model. The changes of kinetic parameters in the raising and lowering processes of the ladder set are investigated. The obtained results can be the fundamentals for modeling, experiments and applications of turntable ladders.

Functionalization of Ti-40Nb implant material with strontium by reactive sputtering

Markus Göttlicher,Marcus Rohnke,Yannik Moryson,Jürgen Thomas,Joachim Sann,Anja Lode,Matthias Schumacher,Romy Schmidt,Stefan Pilz,Annett Gebert,Thomas Gemming,Jürgen Janek 한국생체재료학회 2017 생체재료학회지 Vol.21 No.4

Background: Surface functionalization of orthopedic implants with pharmaceutically active agents is a modern approach to enhance osseointegration in systemically altered bone. A local release of strontium, a verified bone building therapeutic agent, at the fracture site would diminish side effects, which could occur otherwise by oral administration. Strontium surface functionalization of specially designed titanium-niobium (Ti-40Nb) implant alloy would provide an advanced implant system that is mechanically adapted to altered bone with the ability to stimulate bone formation. Methods: Strontium-containing coatings were prepared by reactive sputtering of strontium chloride (SrCl2) in a self-constructed capacitively coupled radio frequency (RF) plasma reactor. Film morphology, structure and composition were investigated by scanning electron microscopy (SEM), time of flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). High-resolution transmission electron microscopy (HR-TEM) was used for the investigation of thickness and growth direction of the product layer. TEM lamellae were prepared using the focused ion beam (FIB) technique. Bioactivity of the surface coatings was tested by cultivation of primary human osteoblasts and subsequent analysis of cell morphology, viability, proliferation and differentiation. The results are correlated with the amount of strontium that is released from the coating in biomedical buffer solution, quantified by inductively coupled plasma mass spectrometry (ICP-MS). Results: Dense coatings, consisting of SrOxCly, of more than 100 nm thickness and columnar structure, were prepared. TEM images of cross sections clearly show an incoherent but well-structured interface between coating and substrate without any cracks. Sr2+ is released from the SrOxCly coating into physiological solution as proven by ICP-MS analysis. Cell culture studies showed excellent biocompatibility of the functionalized alloy. Conclusions: Ti-40Nb alloy, a potential orthopedic implant material for osteoporosis patients, could be successfully plasma coated with a dense SrOxCly film. The material performed well in in vitro tests. Nevertheless, the Sr2+ release must be optimized in future work to meet the requirements of an effective drug delivery system.

Comparison of Spot Sign, Blend Sign and Black Hole Sign for Outcome Prediction in Patients with Intracerebral Hemorrhage

Peter B. Sporns,Michael Schwake,André Kemmling,Jens Minnerup,Wolfram Schwindt,Thomas Niederstadt,Rene Schmidt,Uta Hanning 대한뇌졸중학회 2017 Journal of stroke Vol.19 No.3

Background and Purpose Blend sign (BS) and black hole sign (BHS) on non-contrast computed tomography (NCCT) and spot sign (SS) on CT-angiography (CTA) are indicators of early hematoma expansion in spontaneous intracerebral hemorrhage (ICH). However, their independent contributions to outcome have not been well explored. Methods In this retrospective study, inclusion criteria were: 1) spontaneous ICH and 2) NCCT and CTA performed on admission within 6 hours after onset of symptoms. Discharge outcome was dichotomized as good (modified Rankin Scale [mRS] 0-3) and poor (mRS 4-6) outcomes. The impacts of BHS, BS and SS on outcome were assessed in univariate and multivariable logistic regression models. Results Of 182 patients with spontaneous ICH, 26 (14.3%) presented with BHS, 37 (20.3%) with BS and 39 (21.4%) with SS. There was a substantial correlation between SS and BS (κ=0.701) and a moderate correlation between SS and BHS (κ=0.424). In univariable logistic regression, higher baseline hematoma volume (P<0.001), intraventricular hemorrhage (P=0.002) and the presence of BHS/BS/SS (all P<0.001) on admission CT scan were associated with poor outcome. Multivariable analysis identified intraventricular haemorrhage (odds ratio [OR] 2.22 per mL, P=0.022), baseline hematoma volume (OR 1.03 per mL, P<0.001) and SS on CTA (OR 11.43, P<0.001) as independent predictors of poor outcome, showing that SS compared to BS and BHS was more powerful to predict poor outcome. Conclusions The NCCT BHS and BS are correlated with the CTA SS and are reliable predictors of poor outcome in patients with ICH. Of the CT variables indicating early hematoma expansion, SS on CTA was the most reliable outcome predictor. However, given their correlation with SS on CTA, BS and BHS on NCCT can be useful for predicting outcome if CTA is not obtainable.

A Study on Surface Quality and Mechanical Property Improvement Through Mechanical Surface Treatment of Amorphous Metal

Jigeun Nam,Tawoo Kim,Jungkyu Park,Eunae Jo,Nadine Wolf,Thomas Strache,Julia Hahn,Schmidt Matthias,Christian Polak 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.25 No.3

Amorphous metal is used in various applications due to high strength, elastic limit, and excellent soft magnetic properties, but fracture characteristics may deteriorate due to surface roughness or defects generated during manufacturing. So, in this study, we have investigated the effect of mechanical surface treatment on the fracture characteristics of amorphous metal foil. Unlike stainless steel sheets manufactured by the rolling process, amorphous metal foils have a rough surface and surface defects such as fine dimples and stripe patterns generated during the manufacturing process. After mechanical surface treatment such as brushing and grinding, surface roughness and mechanical properties of each specimen were compared. Through surface treatment, surface roughness was improved and defects such as dimple were removed. While the surface roughness Ra value of untreated sample was 0.6 on the wheel side and 0.4 on the air side, after surface treatment, the Ra value was lowered to less than 0.2 on both sides. Tensile tests were conducted to compare the mechanical characteristics of specimens. In case of the brushed or grinded samples, fracture strain increased from 1.5 to 1.8%, but no change in the elastic modulus was observed. Folding tests under repeated bending loads also showed that the durability of the surface treated sample was improved. This is considered to be an effect of eliminating surface defects that begin to crack.

Vertical Graphene Growth from Amorphous Carbon Films Using Oxidizing Gases

Bachmatiuk, Alicja,Boeckl, John,Smith, Howard,Ibrahim, Imad,Gemming, Thomas,Oswald, Steffen,Kazmierczak, Wojciech,Makarov, Denys,Schmidt, Oliver G.,Eckert, Juergen,Fu, Lei,Rummeli, Mark H. American Chemical Society 2015 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.119 No.31

<P>Amorphous carbon thin films are technologically important materials that range in use from the semiconductor industry to corrosion-resistant films. Their conversion to crystalline graphene layers has long been pursued; however, typically this requires excessively high temperatures. Thus, crystallization routes which require reduced temperatures are important. Moreover, the ability to crystallize amorphous carbon at reduced temperatures without a catalyst could pave the way for practical graphene synthesis for device fabrication without the need for transfer or post-transfer gate deposition. To this end we demonstrate a practical and facile method to crystallize deposited amorphous carbon films to high quality graphene layers at reduced annealing temperatures by introducing oxidizing gases during the process. The reactive gases react with regions of higher strain (energy) in the system and accelerate the graphitization process by minimizing criss-cross-linkages and accelerating C–C bond rearrangement at defects. In other words, the movement of crystallite boundaries is accelerated along the carbon hexagon planes by removing obstacles for crystallite coalescence.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-31/acs.jpcc.5b05167/production/images/medium/jp-2015-05167v_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp5b05167'>ACS Electronic Supporting Info</A></P>

Uniform Large-Area Free-Standing Silver Nanowire Arrays on Transparent Conducting Substrates

Feng, Yuyi,Kim, Kwang-Dae,Nemitz, Clayton A.,Kim, Paul,Pfadler, Thomas,Gerigk, Melanie,Polarz, Sebastian,Dorman, James A.,Weickert, Jonas,Schmidt-Mende, Lukas The Electrochemical Society 2016 Journal of the Electrochemical Society Vol.163 No.8

<P>Arrays of silver nanowires have received increasing attention in a variety of applications such as surface-enhanced Raman scattering (SERS), plasmonic biosensing and electrode for photoelectric devices. However, until now, large scale fabrication of device-suitable silver nanowire arrays on supporting substrates has seen very limited success. Here we show the synthesis of free-standing silver nanowire arrays on indium-tin oxide (ITO) coated glass by pulsed electrodeposition into anodic aluminum oxide (AAO) templates. We use an in situ oxygen plasma cleaning process and a sputtered Ti layer to enhance the adhesion between the template and ITO glass. An ultrathin gold layer (2 nm) is deposited as a nucleation layer for the electrodeposition of silver. An unprecedented high level of uniformity and control of the nanowire diameter, spacing and length has been achieved. The absorption measurements show that the free-standing silver nanowire arrays possess tunable plasmonic resonances.</P>

Volcanic aerosol layers observed with multiwavelength Raman lidar over central Europe in 2008-2009

Mattis, Ina,Siefert, Patric,Mü,ller, Detlef,Tesche, Matthias,Hiebsch, Anja,Kanitz, Thomas,Schmidt, Jö,rg,Finger, Fanny,Wandinger, Ulla,Ansmann, Albert American Geophysical Union 2010 Journal of Geophysical Research Vol.115 No.d2

<P>In the framework of regular European Aerosol Research Lidar Network (EARLINET) observations, aerosol layers have been monitored with a multiwavelength aerosol Raman lidar in the upper troposphere and lower stratosphere over Leipzig (51.4 degrees N, 12.4 degrees E), Germany, since the summer of 2008. The origins of these layers are eruptions of different volcanoes on the Aleutian Islands, Kamchatka, Alaska, and on the Kuril Islands. FLEXPART transport simulations show that the volcanic aerosol is advected from Alaska to central Europe within about 7 days. The aerosol layers typically occurred in the upper troposphere above 5 km height and in the lower stratosphere below 25 km height. The optical depths of the volcanic aerosol layers are mostly between 0.004 and 0.025 at 532 nm. The wavelength dependence of the backscatter coefficients and extinction coefficients indicate Angstrom exponents from 1.0-2.0. Lidar ratios in the stratosphere are found in the range from 30-60 sr (355 nm) and 30-45 sr (532 nm). The estimation of the effective radius, surface-area, and mass concentrations of a volcanic aerosol layer, observed well within the stratosphere at end of August 2009, reveals values of 0.1-0.2 mu m, 5-10 mu m(2) cm(-3), and 0.3-0.5 mu g m(-3), respectively.</P>

Confirming the Dual Role of Etchants during the Enrichment of Semiconducting Single Wall Carbon Nanotubes by Chemical Vapor Deposition

Ibrahim, Imad,Kalbacova, Jana,Engemaier, Vivienne,Pang, Jinbo,Rodriguez, Raul D.,Grimm, Daniel,Gemming, Thomas,Zahn, Dietrich R. T.,Schmidt, Oliver G.,Eckert, Jü,rgen,Rü,mmeli, Mark H. American Chemical Society 2015 Chemistry of materials Vol.27 No.17

<P>The search for ways to synthesize single wall carbon nanotubes (SWCNT) of a given electronic type in a controlled manner persists despite great challenges because the potential rewards are huge, in particular as a material beyond silicon. In this work we take a systematic look at three primary aspects of semiconducting enriched SWCNT grown by chemical vapor deposition. The role of catalyst choice, substrate, and feedstock mixture are investigated. In terms of semiconducting yield enhancement, little influence is found from either the binary catalyst or substrate choice. However, a very clear enrichment is found as one adds nominal amounts of methanol to an ethanol feedstock. Yields of up to 97% semiconducting SWCNT are obtained. These changes are attributed to two known etchant processes. In the first, metal SWCNT are preferentially etched. In the second, we reveal etchants also preferentially etch small diameter tubes because they are more reactive. The etchants are confirmed to have a dual role, to preferentially etch metallic tubes and narrow diameter tubes (both metallic and semiconducting) which results in a narrowing of the SWCNT diameter distribution.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-17/acs.chemmater.5b02037/production/images/medium/cm-2015-02037h_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm5b02037'>ACS Electronic Supporting Info</A></P>