[Curriculum "Tracheostomy management in dysphagia therapy"]. / Curriculum "Trachealkanülenmanagement in der Dysphagietherapie".

The number of tracheotomized patients with dysphagia and their need for treatment are continuously increasing in clinical and community settings. The revised version of the directive on home care and community-based intensive care of the Federal Joint Committee (G-BA) requires that tracheotomized patients are regularly evaluated with the aim of identifying and promoting the therapeutic potential after hospital discharge. Dysphagia treatment plays a crucial role as without improvement of severe dysphagia there is practically no possibility for decannulation. Tracheotomized patients with dysphagia are treated by speech and language therapists (SLT); however, the contents of tracheostomy management (TM) are not obligatory in the speech and language therapeutic training curricula, so that there is a need for further education and treatment standards must be secured. Therefore, the German Interdisciplinary Society for Dysphagia (DGD) in cooperation with the participating German medical and therapeutic societies developed a postgraduate curriculum for TM. This should serve as the basis for contents in TM and qualification of therapists within the framework of the delegation of medical services. The goals of the TM curriculum are the definition of theoretical and practical contents of TM, the qualification to perform TM according to current standards of care and quality assurance. The curriculum defines two qualification levels (user and trainer), entry requirements, curricular contents, examination and qualification criteria as well as transitional regulations for SLTs already experienced in TM.

[Curriculum "Tracheostomy management in dysphagia therapy"]. / Curriculum "Trachealkanülenmanagement in der Dysphagietherapie".

The number of tracheotomized patients with dysphagia and their need for treatment are continuously increasing in clinical and community settings. The revised version of the directive on home care and community-based intensive care of the Federal Joint Committee (G-BA) requires that tracheotomized patients are regularly evaluated with the aim of identifying and promoting the therapeutic potential after hospital discharge. Dysphagia treatment plays a crucial role as without improvement of severe dysphagia there is practically no possibility for decannulation. Tracheotomized patients with dysphagia are treated by speech and language therapists (SLT); however, the contents of tracheostomy management (TM) are not obligatory in the speech and language therapeutic training curricula, so that there is a need for further education and treatment standards must be secured. Therefore, the German Interdisciplinary Society for Dysphagia (DGD) in cooperation with the participating German medical and therapeutic societies developed a postgraduate curriculum for TM. This should serve as the basis for contents in TM and qualification of therapists within the framework of the delegation of medical services. The goals of the TM curriculum are the definition of theoretical and practical contents of TM, the qualification to perform TM according to current standards of care and quality assurance. The curriculum defines two qualification levels (user and trainer), entry requirements, curricular contents, examination and qualification criteria as well as transitional regulations for SLTs already experienced in TM.

Longterm course of neuropsychological symptoms and ME/CFS after SARS-CoV-2-infection: a prospective registry study.

A significant proportion of patients after SARS-CoV-2 infection suffer from long-lasting symptoms. Although many different symptoms are described, the majority of patients complains about neuropsychological symptoms. Additionally, a subgroup of patients fulfills diagnostic criteria for ME/CFS. We analyzed a registry of all patients presenting in the out-patients clinic at a German university center. For patients with more than one visit, changes in reported symptoms from first to second visit were analyzed. A total of 1022 patients were included in the study, 411 of them had more than one visit. 95.5% of the patients reported a polysymptomatic disease. At the first visit 31.3% of the patients fulfilled ME/CFS criteria after a median time of 255 days post infection and and at the second visit after a median of 402 days, 19.4% still suffered from ME/CFS. Self-reported fatigue (83.7-72.7%) and concentration impairment (66.2-57.9%) decreased from first to second visit contrasting non-significant changes in the structured screening. A significant proportion of SARS-CoV-2 survivors presenting with ongoing symptoms present with ME/CFS. Although the proportion of subjective reported symptoms and their severity reduce over time, a significant proportion of patients suffer from long-lasting symptoms necessitating new therapeutic concepts.

Optimization of anastomotic technique and gastric conduit perfusion with hyperspectral imaging and machine learning in an experimental model for minimally invasive esophagectomy.

INTRODUCTION: Esophagectomy is the mainstay of esophageal cancer treatment, but anastomotic insufficiency related morbidity and mortality remain challenging for patient outcome. Therefore, the objective of this work was to optimize anastomotic technique and gastric conduit perfusion with hyperspectral imaging (HSI) for total minimally invasive esophagectomy (MIE) with linear stapled anastomosis. MATERIAL AND METHODS: A live porcine model (n = 58) for MIE was used with gastric conduit formation and simulation of linear stapled side-to-side esophagogastrostomy. Four main experimental groups differed in stapling length (3 vs. 6 cm) and simulation of anastomotic position on the conduit (cranial vs. caudal). Tissue oxygenation around the anastomotic simulation site was evaluated using HSI and was validated with histopathology. RESULTS: The tissue oxygenation (ΔStO2) after the anastomotic simulation remained constant only for the short stapler in caudal position (-0.4 ± 4.4%, n.s.) while it was impaired markedly in the other groups (short-cranial: -15.6 ± 11.5%, p = 0.0002; long-cranial: -20.4 ± 7.6%, p = 0.0126; long-caudal: -16.1 ± 9.4%, p < 0.0001). Tissue samples from avascular stomach as measured by HSI showed correspondent eosinophilic pre-necrotic changes in 35.7 ± 9.7% of the surface area. CONCLUSION: Tissue oxygenation at the site of anastomotic simulation of the gastric conduit during MIE is influenced by stapling technique. Optimal oxygenation was achieved with a short stapler (3 cm) and sufficient distance of the simulated anastomosis to the cranial end of the gastric conduit. HSI tissue deoxygenation corresponded to histopathologic necrotic tissue changes. The experimental model with HSI and ML allow for systematic optimization of gastric conduit perfusion and anastomotic technique while clinical translation will have to be proven.

End-to-end learning with interpretation on electrohysterography data to predict preterm birth.

Prediction of preterm birth is a difficult task for clinicians. By examining an electrohysterogram, electrical activity of the uterus that can lead to preterm birth can be detected. Since signals associated with uterine activity are difficult to interpret for clinicians without a background in signal processing, machine learning may be a viable solution. We are the first to employ Deep Learning models, a long-short term memory and temporal convolutional network model, on electrohysterography data using the Term-Preterm Electrohysterogram database. We show that end-to-end learning achieves an AUC score of 0.58, which is comparable to machine learning models that use handcrafted features. Moreover, we evaluate the effect of adding clinical data to the model and conclude that adding the available clinical data to electrohysterography data does not result in a gain in performance. Also, we propose an interpretability framework for time series classification that is well-suited to use in case of limited data, as opposed to existing methods that require large amounts of data. Clinicians with extensive work experience as gynaecologist used our framework to provide insights on how to link our results to clinical practice and stress that in order to decrease the number of false positives, a dataset with patients at high risk of preterm birth should be collected. All code is made publicly available.

Food system actor perspectives on future-proofing European food systems through plant breeding.

Crop improvement is a key innovation area in the pursuit of sustainable food systems. However, realising its potential requires integration of the needs and priorities of all agri-food chain stakeholders. In this study, we provide a multi-stakeholder perspective on the role of crop improvement in future-proofing the European food system. We engaged agri-business, farm- and consumer-level stakeholders, and plant scientists through an online survey and focus groups. Four of each group's top five priorities were shared and related to environmental sustainability goals (water, nitrogen and phosphorus efficiency, and heat stress). Consensus was identified on issues including considering existing alternatives to plant breeding (e.g. management strategies), minimising trade-offs, and addressing geographical variation in needs. We conducted a rapid evidence synthesis on the impacts of priority crop improvement options, highlighting the urgent need for further research examining downstream sustainability impacts to identify concrete targets for plant breeding innovation as a food systems solution.

Combined two-stage total pancreatoduodenectomy and esophagectomy for synchronous malignancy of the pancreatic corpus and the esophagus: A surgical case report.

INTRODUCTION: Synchronous visceral malignancy is rare especially for esophagogastric junction adenocarcinoma combined with malignancy in the pancreas. So far only 7 cases of combined partial pancreatoduodenectomy and esophagectomy for synchronous malignancy have been described in the literature and none for combined total pancreatectomy and esophagectomy. PRESENTATION OF CASE: We report the case of a 67-year-old male patient, who underwent multi-modality treatment including two-stage total pancreatoduodenectomy and subsequent Ivor-Lewis esophagectomy for synchronous adenocarcinoma of the distal esophagus and pancreatic multilocal metastases of a renal cell carcinoma after nephrectomy 17 years ago. Pathology revealed R0 resections for both malignancies and there were no postoperative complications. A 12 months follow-up showed no signs of recurrence and a good quality of life. CONCLUSION: Curative-intent, combined oncological two-stage open total pancreatoduodenectomy and esophagectomy with several days interval is safe and feasible in selected cases when performed by an experienced interdisciplinary team in a high-volume surgical center.

Hypomorphic RAG deficiency: impact of disease burden on survival and thymic recovery argues for early diagnosis and HSCT.

Patients with hypomorphic mutations in the RAG1 or RAG2 gene present with either Omenn syndrome or atypical combined immunodeficiency with a wide phenotypic range. Hematopoietic stem cell transplantation (HSCT) is potentially curative, but data are scarce. We report on a worldwide cohort of 60 patients with hypomorphic RAG variants who underwent HSCT, 78% of whom experienced infections (29% active at HSCT), 72% had autoimmunity, and 18% had granulomas pretransplant. These complications are frequently associated with organ damage. Eight individuals (13%) were diagnosed by newborn screening or family history. HSCT was performed at a median of 3.4 years (range 0.3-42.9 years) from matched unrelated donors, matched sibling or matched family donors, or mismatched donors in 48%, 22%, and 30% of the patients, respectively. Grafts were T-cell depleted in 15 cases (25%). Overall survival at 1 and 4 years was 77.5% and 67.5% (median follow-up of 39 months). Infection was the main cause of death. In univariable analysis, active infection, organ damage pre-HSCT, T-cell depletion of the graft, and transplant from a mismatched family donor were predictive of worse outcome, whereas organ damage and T-cell depletion remained significant in multivariable analysis (hazard ratio [HR] = 6.01, HR = 8.46, respectively). All patients diagnosed by newborn screening or family history survived. Cumulative incidences of acute and chronic graft-versus-host disease were 35% and 22%, respectively. Cumulative incidences of new-onset autoimmunity was 15%. Immune reconstitution, particularly recovery of naïve CD4+ T cells, was faster and more robust in patients transplanted before 3.5 years of age, and without organ damage. These findings support the indication for early transplantation.

Luminescent polyelectrolytes with antiviral activity.

Radical polymerization was used to synthesize and characterize (co)polymers with sodium styrenesulfonate (NaSS), 4-methacryloylamidosalicylic acid (MASA), and N-vinylpyrrolidone, which have a low cytotoxicity and a high antiviral activity against the human respiratory syncytial virus. The interaction of copolymers with Tb3+ ions was studied. The complexes formed in dilute aqueous solutions at a concentration of MASA units c ⩽ 1 · 10-4 mol L-1 demonstrate a strong luminescence. The luminescence intensity is independent of copolymer composition, but increases when the NaSS units are substituted with uncharged N-vinylpyrrolidone units. The obtained Tb3+ polymer complexes are promising luminescent sensors for the visualization of biological objects interacting with copolymers.

Feed efficiency of lactating Holstein cows is repeatable within diet but less reproducible when changing dietary starch and forage concentrations.

Improving feed efficiency has become an important target for dairy farmers to produce more milk with fewer feed resources. With decreasing availability of arable land to produce feeds that are edible for human consumption, it will be important to increase the proportion of feeds in the diets for dairy cattle that are less edible for human consumption. The current research analyzed the ability of lactating dairy cows to maintain their feed efficiency when switching between a high starch diet (HS diet: 27% starch, 29% NDF, 47.1% forages on a DM basis) and a low starch diet (LS diet: 13% starch, 37% NDF, 66.4% forages on a DM basis). Sixty-two lactating Holstein cows (137 ± 23 days in milk (DIM) at the start of experiment), of which 29 were primiparous cows, were utilized in a crossover design with two 70-d experimental periods, including a 14-d adaption period for each. Feed efficiency was estimated as the individual deviation from the population average intercept in a mixed model predicting DM intake (DMI) with net energy in milk, maintenance and BW gain and loss. Repeatability was estimated within each diet by comparing feed efficiency estimated over the first 28-day period and the second 28-day period within each diet, using Pearson's and intraclass correlations, and the estimation of error of repeatability. Similarly, reproducibility was estimated by comparing the second 28-day period of one diet with the first 28-day period of the other diet. Feed efficiency was less reproducible across diets than repeatable within the same diet. This was shown by lower intraclass correlations (0.399) across diets compared to that in the HS diet (0.587) and LS diet (0.806), as well as a lower Pearson's correlation coefficient (0.418) across diets compared to that in the HS diet (0.630) and LS diet (0.809). In addition, the estimation of error of repeatability was higher (0.830 kg DM/d) across diets compared to that in the HS diet (0.761 kg DM/d) and LS diet (0.504 kg DM/d). This means that the feed efficiency of dairy cows is more likely to change after a diet change than over subsequent lactation stages. Other determinants, such as digestive processes, need to be further investigated to determine its effects on estimating feed efficiency.

2D crystal structure and anisotropic magnetism of GdAu6.75-xAl0.5+x (x ≈ 0.54).

Exploration of the gold-rich part of the ternary Gd-Au-Al system afforded the intermetallic compound GdAu6.75-xAl0.5+x (x ≈ 0.54) which was structurally characterized by single crystal X-ray diffraction (Pnma, a = 18.7847(4) Å, b = 23.8208(5) Å, c = 5.3010(1) Å). GdAu6.75-xAl0.5+x crystallizes in a previously unknown structure type featuring layers of Gd2(Au, Al)29 and Gd2(Au, Al)28 clusters which are arranged as in a close-packing parallel to the ac plane. The Gd substructure corresponds to slightly corrugated 36 nets (dGd-Gd = 5.30-5.41 Å) which are stacked on top of each other along the b direction with alternating short (5.4, 5.6 Å, within layers) and long distances (6.4 Å, between layers). The title compound has been discussed with respect to a quasicrystal approximant (1/1 AC) GdAu5.3Al in the same system. The magnetic properties of GdAu6.75-xAl0.5+x were found to be reminiscent to those of some ternary ACs, with sharp peaks in the temperature dependent magnetization, and metamagnetic-like transitions. The material becomes antiferromagnetic below 25 K; magnetometry results suggest that the antiferromagnetic state is composed of ferromagnetic ac planes, coupled antiferromagnetically along the b direction.

Characteristics and motivational factors for joining a lay responder system dispatch to out-of-hospital cardiac arrests.

BACKGROUND: There has been in increase in the use of systems for organizing lay responders for suspected out-of-hospital cardiac arrests (OHCAs) dispatch using smartphone-based technology. The purpose is to increase survival rates; however, such systems are dependent on people's commitment to becoming a lay responder. Knowledge about the characteristics of such volunteers and their motivational factors is lacking. Therefore, we explored characteristics and quantified the underlying motivational factors for joining a smartphone-based cardiopulmonary resuscitation (CPR) lay responder system. METHODS: In this descriptive cross-sectional study, 800 consecutively recruited lay responders in a smartphone-based mobile positioning first-responder system (SMS-lifesavers) were surveyed. Data on characteristics and motivational factors were collected, the latter through a modified version of the validated survey "Volunteer Motivation Inventory" (VMI). The statements in the VMI, ranked on a Likert scale (1-5), corresponded to(a) intrinsic (an inner belief of doing good for others) or (b) extrinsic (earning some kind of reward from the act) motivational factors. RESULTS: A total of 461 participants were included in the final analysis. Among respondents, 59% were women, 48% between 25 and 39 years of age, 37% worked within health care, and 66% had undergone post-secondary school. The most common way (44%) to learn about the lay responder system was from a CPR instructor. A majority (77%) had undergone CPR training at their workplace. In terms of motivation, where higher scores reflect greater importance to the participant, intrinsic factors scored highest, represented by the category values (mean 3.97) followed by extrinsic categories reciprocity (mean 3.88) and self-esteem (mean 3.22). CONCLUSION: This study indicates that motivation to join a first responder system mainly depends on intrinsic factors, i.e. an inner belief of doing good, but there are also extrinsic factors, such as earning some kind of reward from the act, to consider. Focusing information campaigns on intrinsic factors may be the most important factor for successful recruitment. When implementing a smartphone-based lay responder system, CPR instructors, as a main information source to potential lay responders, as well as the workplace, are crucial for successful recruitment.

The use of 3-dimensional imaging of Holstein cows to estimate body weight and monitor the composition of body weight change throughout lactation.

Three-dimensional (3D) imaging offers new possibilities in animal phenotyping. Here, we investigated how this technology can be used to study the morphological changes that occur in dairy cows over the course of a single lactation. First, we estimated the individual body weight (BW) of dairy cows using traits measured with 3D images. To improve the quality of prediction, we monitored body growth (via 3D imaging), gut fill (via individual dry matter intake), and body reserves (via body condition score) throughout lactation. A group of 16 Holstein cows-8 in their first lactation, 4 in their second lactation, and 4 in their third or higher lactation-was scanned in 3D once a month for an entire lactation. Values of morphological traits (e.g., chest depth or hip width) increased continuously with parity, but cows in their first lactation experienced the largest increase during the monitoring period. Values of partial volume, estimated from point of shoulder to pin bone, predicted BW with an error of 25.4 kg (R2 = 0.92), which was reduced to 14.3 kg when the individual effect of cows was added to the estimation model. The model was further improved by the addition of partial surface area (from point of shoulder to pin bone), hip width, chest depth, diagonal length, and heart girth, which increased the R2 of BW prediction to 0.94 and decreased root mean square error to 22.1 kg. The different slopes for individual cows were partly explained by body condition score and morphological traits, indicating that they may have reflected differences in body density among animals. Changes in BW over the course of lactation were mostly due to changes in growth, which accounted for around two-thirds of BW gain regardless of parity. Body reserves and gut fill had smaller but still notable effects on body composition, with a higher gain in body reserves and gut fill for cows in their first lactation compared with multiparous cows. This work demonstrated the potential for rapid and low-cost 3D imaging to facilitate the monitoring of several traits of high interest in dairy livestock farming.

Long-term safety and efficacy of lentiviral hematopoietic stem/progenitor cell gene therapy for Wiskott-Aldrich syndrome.

Patients with Wiskott-Aldrich syndrome (WAS) lacking a human leukocyte antigen-matched donor may benefit from gene therapy through the provision of gene-corrected, autologous hematopoietic stem/progenitor cells. Here, we present comprehensive, long-term follow-up results (median follow-up, 7.6 years) (phase I/II trial no. NCT02333760 ) for eight patients with WAS having undergone phase I/II lentiviral vector-based gene therapy trials (nos. NCT01347346 and NCT01347242 ), with a focus on thrombocytopenia and autoimmunity. Primary outcomes of the long-term study were to establish clinical and biological safety, efficacy and tolerability by evaluating the incidence and type of serious adverse events and clinical status and biological parameters including lentiviral genomic integration sites in different cell subpopulations from 3 years to 15 years after gene therapy. Secondary outcomes included monitoring the need for additional treatment and T cell repertoire diversity. An interim analysis shows that the study meets the primary outcome criteria tested given that the gene-corrected cells engrafted stably, and no serious treatment-associated adverse events occurred. Overall, severe infections and eczema resolved. Autoimmune disorders and bleeding episodes were significantly less frequent, despite only partial correction of the platelet compartment. The results suggest that lentiviral gene therapy provides sustained clinical benefits for patients with WAS.

Combining datasets in a dynamic residual feed intake model and comparison with linear model results in lactating Holstein cattle.

A new method to estimate residual feed intake (RFI) was recently developed based on a multi-trait random regression model. This approach deals with the dynamic nature of the lactation, which is in contrast with classical linear approaches. However, an issue remains: pooling data across sites and years, which implies dealing with different (and sometimes unknown) diet energy contents. This will be needed for genomic evaluation. In this study, we tested whether merging two individual datasets into a larger one can lead to valuable results in comparison to analysing them on their own with the multi-trait random regression model. Three datasets were defined: the first one with 1 063 lactations, the second one with 205 lactations from a second farm and the third one combining the data of the two first datasets (1 268 lactations). The model was applied to the three datasets to estimate individual RFI as well as variance components and correlations between the four traits included in the model (fat and protein corrected milk production, BW, feed intake and body condition score), and a fixed month-year-farm effect was used to define the contemporary group. The variance components and correlations between animal effects of the four traits were very similar irrespective of the dataset used with correlations higher than 0.94 between the different datasets. The RFI estimates for animals from their single farm only were also very similar (r > 0.95) to the ones computed from the merged dataset (Dataset 3). This highlights that the contemporary group correction in the model adequately accounts for differences between the two feeding environments. The dynamic model can thus be used to produce RFI estimates from merged datasets, at least when animals are raised in similar systems. In addition, the 205 lactations from the second farm were also used to estimate the RFI with a linear approach. The RFI estimated by the two approaches were similar when the considered period was rather short (r = 0.85 for RFI for the first 84 days of lactation) but this correlation weakened as the period length grew (r = 0.77 for RFI for the first 168 days of lactation). This weakening in correlations between the two approaches when increasing the used time-period reflects that only the dynamic model permits the regression coefficients to evolve in line with the physiological changes through the lactation. The results of this study enlarge the possibilities of use for the dynamic RFI model.

[Experimental cadaveric study assesing protection and osteotomy guide system (BARU) in hallux valgus surgery using Reverdin-Isham technic]. / Estudio experimental cadavérico para valorar el sistema de protección y guía de osteotomía (BARU) en cirugías de hallux valgus con técnica de Reverdin-Isham.

INTRODUCTION: Hallux valgus is a high frequency disorder, affecting the first ray. Operative correction techniques have grown popularity lately. One of them is the Reverdin-Isham technique (first metatarsal medial incomplete osteotomy). Recently, a protection and osteotomy cutting guide has been developed: the BARU system. OBJECTIVE: To test the usefulness of the BARU system as a protective factor for soft structures adjacent to the surgical site and guidance for osteotomy. MATERIAL AND METHODS: Experimental cadaveric study. Six cadaveric feet (two fresh-frozen and four in formaldehyde solution), unapproached. Feet were numbered and intervened with RI technique, three of them with BARU system and three without it. Afterwards, dissection by two dissectors who did not know whether the BARU system had been used or not, establishing a single-blinded model. 13 structures were evaluated in each foot. Data was recovered into Microsoft Office Excel and processed with SPSS. 2 test (significative if p value < 0.05) and relative risk were calculated. RESULTS: Approach using BARU system was satisfactory, with usual-size operation-ports. BARU system colocation was simple and radiological control showed adequate spatial location. The device contributed as reference for cutting direction and depth. 65 out of the 78 searched structures were found (83.3%). Six injuries were found among the assessed structures: plantar medial nerve (one injury), plantar medial artery (one injury), flexor brevis muscle (three injuries), abductor muscle (one injury). Five of these injuries occurred in non-utilizing BARU system feet. CONCLUSION: Promising results in terms of protection of nearby structures, cutting guide, and ease of intervention. Avoids X-rays exposure. Not significant statistical calculations, the sample should be enlarged.

INTRODUCCIÓN: El hallux valgus es una patología con alta prevalencia en la población. Técnicas de corrección quirúrgica han crecido en popularidad últimamente. Una de ellas es la de Reverdin-Isham (RI: osteotomía incompleta medial en primer metatarsiano), se desarrolló un dispositivo de protección y guía de corte para dicho procedimiento: el sistema BARU. OBJETIVO: Probar la utilidad del sistema BARU como factor protector de estructuras blandas adyacentes al sitio de abordaje y guía para osteotomía. MATERIAL Y MÉTODOS: Estudio cadavérico; seis pies (dos frescos y cuatro formolados) sin abordajes previos. Tres con el sistema BARU y tres sin éste. Posteriormente disección por dos disectores con enmascaramiento simple ciego. Se evaluaron 13 estructuras en cada pie. Los datos fueron recabados con Microsoft Office Excel y procesados en SPSS. Se realizó test de 2 (valor p < 0.05 significativo) y se calculó el riesgo relativo. RESULTADOS: El sistema BARU fue satisfactorio. Su colocación fue sencilla y el control radiológico mostró adecuada ubicación espacial. Ayudó como referencia para la dirección y profundidad del corte. Se encontraron 65 de las 78 estructuras buscadas (83.3%). En las estructuras evaluadas hubo seis lesiones: nervio plantar medial (uno dañado), arteria plantar medial (uno dañado), músculo flexor corto (tres dañados), músculo abductor (uno dañado). Cinco de estas lesiones ocurrieron en pies donde no se utilizó el sistema BARU. CONCLUSIÓN: Resultados prometedores en cuanto a protección de estructuras cercanas, guía de corte y facilidad para la intervención. Cálculos estadísticos no significativos, la muestra debería ampliarse.

Fretting-corrosion of CoCr-alloys against TiAl6V4: The importance of molybdenum in oxidative biological environments.

Periprosthetic fluids often contain reactive oxygen species, including H2O2, that are generated during inflammatory processes. Here, we investigated the fretting-corrosion behavior of CoCrX-alloys (X = Mo, Fe) in a complex protein-containing lubricant, with and without the addition of H2O2. Given the known protective role of molybdenum as an alloying element in metal degradation, we considered its effects by designing a two-way factorial experiment. The aim of the study was to investigate tribocorrosive mechanisms in modular joints of knee and hip prostheses. A previously described test-rig was used to run fretting corrosion tests of CoCrX-alloys with (X=Mo) and without (X=Fe) molybdenum against TiAl6V4 in bovine calf serum (BCS) with and without a physiological relevant H2O2 level (3 mM) in gross slip mode (4 Hz, ±50 µm, pmax=0.18 GPa, 37 °C, 50,000 cycles). Two CoCr-pins were pressed against a cylindrical TiAl6V4-rod, forming a line contact. Normal and frictional forces, the displacement, and the open circuit potential (OCP) were measured and recorded continuously. The dissipated frictional work was independent of alloy composition. The addition of H2O2 lowered the dissipated frictional work and increased wear, and this was significant in the absence of Mo. The mean OCP value was lower with Mo-containing than with Mo-free alloy in both pure BCS (p = .042), and BCS ± H2O2 (p < .0005). The wear scar was deeper for the Mo-free alloy, and this was significant (p = .013) in the presence of H2O2. These findings suggest a marked weakening of the passive film in the presence of H2O2, which is mitigated by the availability of Mo.

Stereoscopic particle image velocimetry in inhomogeneous refractive index fields of combustion flows.

Particle image velocimetry (PIV) measurements in reactive flows are disturbed by inhomogeneous refractive index fields, which cause measurement deviations in particle positions due to light refraction. The resulting measurement errors are known for standard PIV, but the measurement errors for stereoscopic PIV are still unknown. Therefore, for comparison, the velocity errors for standard and stereoscopic PIV are analyzed in premixed propane flames with different Reynolds numbers. For this purpose, ray-tracing simulations based on the time-averaged inhomogeneous refractive index fields of the studied non-swirled flame flows measured by the background-oriented Schlieren technique are performed to quantify the resulting position errors of the particles. In addition, the performance of the volumetric self-calibration relevant to tomographic PIV is analyzed with respect to the remaining position errors of the particles within the flames. The position errors cause significant standard PIV errors of 2% for the velocity component radial to the burner symmetry axis. Stereoscopic PIV measurements result in measurement errors of up to 3% radial to the burner axis and 13% for the velocity component perpendicular to the measurement plane. Due to the lower refractive index gradients in the axial direction, no significant velocity errors are observed for the axial velocity component. For the investigated flame configurations, the position errors and velocity errors increase with the Reynolds numbers. However, this dependence needs to be verified for other flame configurations such as swirled flame flows.