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Germs are present in all areas of everyday life and can lead to dangerous infections. Surfaces with antimicrobial properties are used to reduce the risk of infection in sanitary facilities and hospitals. Apart from the addition of biocides or antibiotic agents to synthetic materials, research shows that it is possible to use the semiconductor titanium dioxide (TiO2) to generate antibacterial surfaces. Photocatalytically active TiO2 leads to the development of reactive oxygen species (ROS) that are able to kill germs. The aim of this research is to use TiO2 to generate antibacterial bulk material. Nanostructured TiO2 particles were incorporated into silicone rubber to obtain a photocatalytic active polymer surface. High temperature vulcanizing (HTV) silicone rubber was used as a matrix material, and samples with 10 wt% of TiO2 were produced. The distribution of TiO2 particles in the matrix was analyzed via light microscopy. The photocatalytic activity on the surface of the test samples was studied via microbial testing with E.coli bacteria. The samples showed different intensities of the photocatalytic effect depending on the type of additive. The effort to create a germ reducing silicone rubber surface by using TiO2 as an additive was successful.

The transmission of pathogens via surfaces poses a major health problem, particularly in hospital environments. Antimicrobial surfaces can interrupt the path of spread, while photocatalytically active titanium dioxide (TiO2) nanoparticles have emerged as an additive for creating antimicrobial materials. Irradiation of such particles with ultraviolet (UV) light leads to the formation of reactive oxygen species that can inactivate bacteria. The aim of this research was to incorporate TiO2 nanoparticles into a cellulose-reinforced melamine-formaldehyde resin (MF) to obtain a photocatalytic antimicrobial thermoset, to be used, for example, for device enclosures or tableware. To this end, composites of MF with 5, 10, 15, and 20 wt% TiO2 were produced by ultrasonication and hot pressing. The incorporation of TiO2 resulted in a small decrease in tensile strength and little to no decrease in Shore D hardness, but a statistically significant decrease in the water contact angle. After 48 h of UV irradiation, a statistically significant decrease in tensile strength for samples with 0 and 10 wt% TiO2 was measured but with no statistically significant differences in Shore D hardness, although a statistically significant increase in surface hydrophilicity was measured. Accelerated methylene blue (MB) degradation was measured during a further 2.5 h of UV irradiation and MB concentrations of 12% or less could be achieved. Samples containing 0, 10, and 20 wt% TiO2 were investigated for long-term UV stability and antimicrobial activity. Fourier-transform infrared spectroscopy revealed no changes in the chemical structure of the polymer, due to the incorporation of TiO2, but changes were detected after 500 h of irradiation, indicating material degradation. Specimens pre-irradiated with UV for 48 h showed a total reduction in Escherichia coli when exposed to UV irradiation.

Purpose The fixation of revision total knee arthroplasties (rTKA) tends to be difficult, leading to a reduction in implant survival. One option for achieving a more stable anchorage is to use metaphyseal cones and sleeves. The objective of the present paper is to provide a current comparative meta-analysis on survival and clinical results of cones vs. sleeves, with a differentiation between the short- and long-term outcome. Methods A search of the literature was conducted systematically to include original papers from 2010 to June 2021. The following parameters were taken into account: revision for aseptic loosening, revision for any reason, periprosthetic joint infections (PJI), KSS as well as KSFS. Studies with a mean follow-up of at least 60 months were defined to be long-term follow-up studies (LT). All other studies were included in the short-term (ST) study analysis. A pooled incidence was used as a summary statistic using a random intercept logistic regression model. Results The present meta-analysis included 43 publications with 3008 rTKA. Of these, 23 publications with 1911 cases were allocated to the sleeve group (SG) and 20 papers with 1097 cases to the cone group (CG). CG showed overall numerically higher complication rates in short- and long-term follow-up, compared with SG. Aseptic loosening occurred at a rate of 0.4% in SG (LT) and 4.1% in CG (LT) (p = 0.09). Periprosthetic joint infection (PJI) was more frequent in the cone group (7% in ST and 11.7% in LT) than in the sleeve group (3.4% in ST and 4.9% in LT, p = 0.02 both). The total revision rate was 5.5% in SG (LT) and 14.4% in CG (LT) (p = 0.12). The clinical scores were also comparable between the two groups. Hinged prothesis were used more frequent in the cone group (ST p p = 0.10), whereas CC type protheses were used more frequently in the sleeve group (ST p p Conclusions This meta-analysis takes into account the longest follow-up periods covered to date. Both cones and sleeves represent a reliable fixation method in the case of severe bone loss in rTKA, although the higher rate of PJI after cone fixation remains a source of concern. A metaphyseal fixation of hinged implants should be taken into account. Level of evidence II (meta-analysis).

Background To differentiate effects of ventricular asynchrony from an underlying hypocontractile cardiomyopathy this study aimed to enhance the understanding of functional impairment and structural remodeling in idiopathic left bundle-branch block (LBBB). We hypothesize, that functional asynchrony with septal flash volume effects alone might not entirely explain the degree of functional impairment. Hence, we suggest the presence of a superimposed contractile cardiomyopathy. Methods In this retrospective study, 53 patients with idiopathic LBBB were identified and matched to controls with and without cardiovascular risk factors. Cardiovascular magnetic resonance (CMR) was used to evaluate cardiac function, volumes and myocardial fibrosis using native T1 mapping and late gadolinium enhancement (LGE). Septal flash volume was assessed by CMR volumetric measurements and allowed to stratify patients with systolic dysfunction solely due to isolated ventricular asynchrony or superimposed contractile impairment. Results Reduced systolic LV-function, increased LV-volumes and septal myocardial fibrosis were found in patients with idiopathic LBBB compared to healthy controls. LV-volumes increased and systolic LV-function declined with prolonged QRS duration. Fibrosis was typically located at the right ventricular insertion points. Subgroups with superimposed contractile impairment appeared with pronounced LV dilation and increased fibrotic remodeling compared to individuals with isolated ventricular asynchrony. Conclusions The presence of superimposed contractile impairment in idiopathic LBBB is crucial to identify patients with enhanced structural remodeling. This finding suggests an underlying cardiomyopathy. Future studies are needed to assess a possible prognostic impact of this entity and the development of heart failure. Trial registration: This study was retrospectively registered.

Ageing, disease and osteoporosis treatment have been linked to accumulation of microdamage, which is caused by repetitive loading and may eventually causes fatigue failure of bones. Post-hoc investigations for in vivo loading and in vitro experiments have been developed to better understand microdamage formation. In this context, previous studies were not able to discriminate the effects caused by structural changes of the trabecular network from differences of tissue/material properties on microdamage formation. In the present study a fatigue test protocol was established to induce microdamage at a defined tensile stress state of individual trabeculae. Further, a thorough analysis of microdamage analysis was presented for 2D and 3D confocal images, enabling a comparison between the tissue and the meso-scale. Eight individual trabeculae were tested for 1500 cycles, six for 2100 cycles and seven for 3000 cycles (close to failure). Microdamage increased slowly from 1500 to 2100 cycles and showed a rapid increase at 3000 cycles. Diffuse damage was mainly present, although also linear microcracks were visible at 2100 and 3000 cycles. Average microcrack length was 93 µm and diffuse damage density was 4.4% for samples tested for 3000 cycles, comparable to previous studies on trabecular bone cores. Only one to three large microdamage sites were observed in the central region, connected to the trabecular surface with small straight cracks. The presented procedure is a first step to better understand how microdamage formation is influenced by material properties in aged and diseased bone, independently of deteriorated trabecular microarchitecture.

Introduction Left bundle-branch block (LBBB) is associated with underlying cardiovascular abnormalities, such as dilated cardiomyopathy and coronary heart disease. However, an isolated LBBB can be found in individuals without detectable cardiovascular disease. Echocardiographic studies demonstrated a reduced left ventricular (LV) ejection fraction (EF) and an increased LV cavity volume and mass in patients with isolated LBBB. Recent studies have shown larger cavity volumes (end-diastolic volume – EDV; end-systolic volume – ESV) and lower LVEF using CMR. However, there is still limited data on cardiac function, volumes and mass and the correlation between the parameters and the QRS duration (QRS) in patients with isolated LBBB. Purpose In this retrospective study LV function, volume, mass, T1-values and myocardial strain were measured and correlation between QRS duration in patients with isolated LBBB was identified using CMR. Methods Potential cases were identified from our local database, who underwent CMR during 2015–2018. We excluded patients with echocardiographic abnormalities besides abnormal septal motion or greater than a mild valve disease, known cardiovascular disease (coronary artery disease, cardiomyopathy or arrhythmia), history of potential cardiotoxic chemotherapy. We could identify 26 adults, who underwent CMR in a 1.5- or 3-Tesla scanner. LBBB was confirmed by ECG prior to CMR by a cardiologist. T1-values (MOLLI) were available in 19 patients. Myocardial strain (tissue tracking) could be performed in 23 patients. Associations were tested using Pearson's correlation analysis. Results 26 patients (age 61.5±9.6 years, 19 women, BMI 25.4 (18.2–38.1)) with isolated LBBB were included (QRS duration: 138±12ms). CMR results in the cohort revealed a reduced LVEF (53.4±3,8%) and slightly enlarged LV cavity when corrected to body-surface area (BSA) (LV-EDV/BSA: 83.7±13.8ml/m2; LV-ESV/BSA: 39.3±8.6ml/m2), when compared to normal values from the study center. There is a negative correlation between LVEF and QRS duration (r=−0.550, p Conclusion Using CMR a negative correlation between LV function and QRS duration and the positive correlation between LV volumes and QRS duration in patients with isolated LBBB could be identified. The absence of significant myocardial fibrosis with normal T1-values indicates an electromechanical dissociation rather than an underlying myocardial abnormality as an explanation for the reduced LVEF.

Bacteria are present in all areas of everyday life and can lead to dangerous infections. Surfaces with antimicrobial properties are used to reduce the risk of infection in sanitary facilities and hospitals. Apart from the addition of biocides or antibiotic agents to synthetic materials, recent research show, that it is possible to use the semiconductor titanium dioxide (TiO2) to generate antibacterial surfaces. The photocatalytically active TiO2 leads to the development of reactive oxygen species (ROS) that are able to kill bacteria. The aim of this research is to generate silicone rubbers with a photocatalytically active surface that has the possibility to lead to an antimicrobial property by incorporating the additive TiO2 into the bulk material. AEROXIDE® TiO2 P25 was used. As matrix material representatives of the three silicone rubber classes were tested. A room-temperature-vulcanization silicone rubber (RTV), a liquid silicone rubber (LSR) and a high-temperature-vulcanization silicone rubber (HTV) were examined. Compounds with various concentrations of TiO2 were produced and the influence on the cross-linking reaction was investigated using differential scanning calorimetry (DSC). The photocatalytic effect on the surface of the modified material was studied via contact angle measurements and methylene blue tests. The DSC analysis showed that titanium dioxide inhibits the curing of the additivated RTV and LSR. The incorporation of TiO2 in the HTV matrix material up to 15 wt% was possible, with an extension of the cross-linking time. The investigation of the HTV siivone rubbers considering the photocatalytic effect yield different results. While the expected photo-induced hydrophilic effect could not be verified for the modified HTV silicone rubbers. However the methylene blue trial showed a high significant discoloration of the titanium dioxide addtivtated HTV polymer and proves that a photocatalytic active HTV silicone rubber surface can be produced using the additive titanium dioxide.

To establish photopolymers for the production of class II or class III medical products by additive manufacturing it is essential to know which components of photopolymeric systems, consisting of monomers, photoinitiators and additives, are the determining factors on their biocompatible properties. In this study the leachable substances of a cured photopolymeric system were eluted and identified by HPLC-MS detection. In addition the cured photopolymer was testes for cytotoxicity and genotoxicity according to DIN EN ISO 10993 for long time applications. The results showed that uncured residual monomers are the determining factor on the biocompatible properties of the photopolymeric system. Strategies to reduce these residual monomers in the cured photopolymer are presented.

Trabecular bone is located inside flat bones as well as in the epi- and metaphysis of long bones and plays a key role with respect to load transfer. Disorders, such as osteoporosis, weaken the structural integrity and may also cause changes in the mechanical properties of individual trabeculae, such as Young's modulus. Knowledge of mechanical tissue properties are necessary to assess risk of bone fracture with finite element analysis (FEA). However, such parameters are most often obtained from experiments on air-dried specimens which do not reflect the physiological conditions. In this study, micro-tensile tests of individual bovine trabeculae were performed until fracture to evaluate the influence of hydration state on the elastic and post-yield behavior. Dehydration resulted in significantly (p 0.001) lower post yield work and ultimate strain, whereas stiffness, yield stress and ultimate stress were significantly (p 0.001) larger. Further, inelastic strain of dehydrated samples was confined to a small region, whereas it was distributed over a larger area in wet samples. Similarly, microdamage accumulation was confined to a significantly smaller region (p 0.05) in dry samples, compared to wet ones. Thus, damage localization resulted in a quasi-brittle failure in dry samples. In contrast, hydrated samples showed a much larger area of microdamage accumulation, resulting in a ductile failure. These results emphasize the need to keep bone samples hydrated during mechanical testing. Sequentially, the findings may help to improve clinical applications like FEA-based bone strength predictions.

Die asymmetrische Dearomatisierung von N-Heterocyclen ist ein wichtiges Verfahren zur Synthese bioaktiver und praparativ wertvoller chiraler Heterocyclen. Allerdings stellt die katalytische, enantio- und regioselektive Dearomatisierung der einfachsten sechsgliedrigen N-Heteroarene, der Pyridine, immer noch eine Herausforderung dar. In dieser Arbeit prasentieren wir die erste hoch enantioselektive, nukleophile Dearomatisierung von Pyridinen durch Anionenbindungskatalyse mit Triazol-basierten H-Donor-Katalysatoren. Im Vergleich zu den gelaufigen NH-basierten H-Bindungsdonoren zeigt dieser Organokatalysator eine sehr viel hohere C2-Regioselektivitat. Er ist in der Lage, hohe Enantioselektivitaten zu induzieren, indem er einen chiralen Ionenpaar-Komplex mit einem ionischen N-Acylpyridinium-Intermediat bildet. Die Methode bietet eine direkte und nutzliche Synthese von chiralen N-Heterocyclen ausgehend von kommerziell erhaltlichen Pyridinen.

The first enantioselective synthesis of chiral heterocyclic α-amino phosphonates by nucleophilic dearomatization of quinolines and pyridines using an anion-binding organocatalysis approach is described. Chiral tetrakistriazoles were employed as efficient hydrogen-bond donor catalysts by forming a chiral close ion-pair with the in situ formed N-acyl salts and 2,2,2-trichlorethoxycarbonyl chloride (TrocCl). The ion-pair was subsequently treated with various phosphorus nucleophiles, such as silyl-protected dialkyl- and trialkylphosphites. Thus, the corresponding products were obtained in complete or high regioselectivities and up to 97:3 e.r. for quinolines or up to 89:11 e.r. for the more challenging pyridine substrates. This method allows for rapid access to substituted chiral cyclic α-amino phosphonates, which can be easily transformed into phosphonic acid derivatives.

Aging leads to gait impairments, which increases the risk for falls. In this study the impact of the auditory feedback system SONIGait on gait parameters in elderly persons was investigated. Twenty-one participants walked at self-selected speed with four variations of real-time auditory feedback of their plantar pressure. Repeated measures ANOVA was utilized to determine changes in time-distance parameters between walking without feedback and four feedback variations. After walking, they completed a questionnaire about their appraisal of the SONIGait system and the four different feedback modalities. There was a significant reduction in gait velocity (0.142 ± 0.04 m/s; p < 0.001) and prolongation of step time (0.02 ± 0.005 s; p < 0.001) during walking with SONIGait. No significant preference for any of the feedback variations was observed. Most participants evaluated the system SONIGait positively. Thus, real-time auditory feedback may be used in gait rehabilitation and may support an older person’s gait stability.

The first anion-binding organocatalyzed enantioselective Reissert-type dearomatization of diazarenes has been developed. This reaction represents a synthetic challenge since diazarenes have various reactive sites. The use of a chiral tetrakistriazole as a C–H-based hydrogen-donor catalyst allowed the straightforward highly regio- and enantioselective synthesis of a variety of chiral diazaheterocycles.

The asymmetric dearomatization of N-heterocycles is an important synthetic method to gain bioactive and synthetically valuable chiral heterocycles. However, the catalytic enantio- and regioselective dearomatization of the simplest six-membered-ring N-heteroarenes, the pyridines, is still very challenging. The first anion-binding-catalyzed, highly enantioselective nucleophilic dearomatization of pyridines with triazole-based H-bond donor catalysts is presented. Contrary to other more common NH-based H-bond donors, this type of organocatalyst shows a prominent higher C2-regioselectivity and is able to promote high enantioinductions via formation of a close chiral anion-pair complex with a preformed N-acyl pyridinium ionic intermediate. This method offers a straightforward and useful synthetic approach to chiral N-heterocycles from abundant and readily available pyridines.

The asymmetric dearomatization of N-heterocycles is an important synthetic method to gain bioactive and synthetically valuable chiral heterocycles. However, the catalytic enantio- and regioselective dearomatization of the simplest six-membered-ring N-heteroarenes, the pyridines, is still very challenging. The first anion-binding-catalyzed, highly enantioselective nucleophilic dearomatization of pyridines with triazole-based H-bond donor catalysts is presented. Contrary to other more common NH-based H-bond donors, this type of organocatalyst shows a prominent higher C2-regioselectivity and is able to promote high enantioinductions via formation of a close chiral anion-pair complex with a preformed N-acyl pyridinium ionic intermediate. This method offers a straightforward and useful synthetic approach to chiral N-heterocycles from abundant and readily available pyridines.

A general and highly enantioselective synthesis of oxygen heterocycles from readily available in situ generated pyrylium derivatives has been realized by embracing a multi‐coordination approach with helical anion‐binding tetrakistriazole catalysts. The high activity of the tetrakistriazole (TetraTri) catalysts, with distinct confined anion‐binding pockets, allows for remarkably low catalyst loadings (down to 0.05 mol %), while providing a simple access to chiral chromanones and dihydropyrones in high enantioselectivities (up to 98:2 e.r.). Moreover, experimental and theoretical studies provide new insights into the hydrogen‐donor ability and key binding interactions of the TetraTri catalysts and its host:guest complexes, suggesting the formation of a 1:3 species.