This study investigates the initial stage of the thermo-mechanical crystallization behavior for uni- and biaxially stretched polyethylene. The models are based on a mesoscale molecular dynamics ...approach. We take constraints that occur in real-life polymer processing into account, especially with respect to the blowing stage of the extrusion blow-molding process. For this purpose, we deform our systems using a wide range of stretching levels before they are quenched. We discuss the effects of the stretching procedures on the micro-mechanical state of the systems, characterized by entanglement behavior and nematic ordering of chain segments. For the cooling stage, we use two different approaches which allow for free or hindered shrinkage, respectively. During cooling, crystallization kinetics are monitored: We precisely evaluate how the interplay of chain length, temperature, local entanglements and orientation of chain segments influence crystallization behavior. Our models reveal that the main stretching direction dominates microscopic states of the different systems. We are able to show that crystallization mainly depends on the (dis-)entanglement behavior. Nematic ordering plays a secondary role.
In this study, we investigate the thermo-mechanical relaxation and crystallization behavior of polyethylene using mesoscale molecular dynamics simulations. Our models specifically mimic constraints ...that occur in real-life polymer processing: After strong uniaxial stretching of the melt, we quench and release the polymer chains at different loading conditions. These conditions allow for free or hindered shrinkage, respectively. We present the shrinkage and swelling behavior as well as the crystallization kinetics over up to 600 ns simulation time. We are able to precisely evaluate how the interplay of chain length, temperature, local entanglements and orientation of chain segments influences crystallization and relaxation behavior. From our models, we determine the temperature dependent crystallization rate of polyethylene, including crystallization onset temperature.
Abstract
Background
Due to the growing economic pressure, there is an increasing interest in the optimization of operational processes within surgical operating rooms (ORs). Surgical departments are ...frequently dealing with limited resources, complex processes with unexpected events as well as constantly changing conditions. In order to use available resources efficiently, existing workflows and processes have to be analyzed and optimized continuously. Structural and procedural changes without prior data-driven analyses may impair the performance of the OR team and the overall efficiency of the department. The aim of this study is to develop an adaptable software toolset for surgical workflow analysis and perioperative process optimization in arthroscopic surgery.
Methods
In this study, the perioperative processes of arthroscopic interventions have been recorded and analyzed subsequently. A total of 53 arthroscopic operations were recorded at a maximum care university hospital (UH) and 66 arthroscopic operations were acquired at a special outpatient clinic (OC). The recording includes regular perioperative processes (i.a. patient positioning, skin incision, application of wound dressing) and disruptive influences on these processes (e.g. telephone calls, missing or defective instruments, etc.). For this purpose, a software tool was developed (‘s.w.an Suite Arthroscopic toolset’). Based on the data obtained, the processes of the maximum care provider and the special outpatient clinic have been analyzed in terms of performance measures (e.g. Closure-To-Incision-Time), efficiency (e.g. activity duration, OR resource utilization) as well as intra-process disturbances and then compared to one another.
Results
Despite many similar processes, the results revealed considerable differences in performance indices. The OC required significantly less time than UH for surgical preoperative (UH: 30:47 min, OC: 26:01 min) and postoperative phase (UH: 15:04 min, OC: 9:56 min) as well as changeover time (UH: 32:33 min, OC: 6:02 min). In addition, these phases result in the Closure-to-Incision-Time, which lasted longer at the UH (UH: 80:01 min, OC: 41:12 min).
Conclusion
The perioperative process organization, team collaboration, and the avoidance of disruptive factors had a considerable influence on the progress of the surgeries. Furthermore, differences in terms of staffing and spatial capacities could be identified. Based on the acquired process data (such as the duration for different surgical steps or the number of interfering events) and the comparison of different arthroscopic departments, approaches for perioperative process optimization to decrease the time of work steps and reduce disruptive influences were identified.
Obtaining large amounts of real patient data involves great efforts and expenses, and processing this data is fraught with data protection concerns. Consequently, data sharing might not always be ...possible, particularly when large, open science datasets are needed, as for AI development. For such purposes, the generation of realistic synthetic data may be the solution. Our project aimed to generate realistic cancer data with the use case of laryngeal cancer.
We used the open-source software Synthea and programmed an additional module for development, treatment and follow-up for laryngeal cancer by using external, real-world (RW) evidence from guidelines and cancer registries from Germany. To generate an incidence-based cohort view, we randomly drew laryngeal cancer cases from the simulated population and deceased persons, stratified by the real-world age and sex distributions at diagnosis.
A module with age- and stage-specific treatment and prognosis for laryngeal cancer was successfully implemented. The synthesized population reflects RW prevalence well, extracting a cohort of 50,000 laryngeal cancer patients. Descriptive data on stage-specific and 5-year overall survival were in accordance with published data.
We developed a large cohort of realistic synthetic laryngeal cancer cases with Synthea. Such data can be shared and published open source without data protection issues.
Experimental data on the interfacial tension of ionic liquids in CO2 and CH4 atmospheres at elevated pressures (up to 20 MPa and 353 K) are presented and discussed. In addition, molecular modeling is ...utilized to describe the thermophysical properties under process-relevant conditions. Molecular modeling has the potential to predict findings in order to avoid costly experiments in the future and to explain the principal behavior of the whole system in terms of simulated concentration profiles. The interfacial tension is recognized to be an important quantity in a number of processes, e.g., for describing multiphase flow. By dissolving within the liquid phase, gases reduce the interfacial tension, which in turn is closely related to the phase behavior. It is shown that the experimentally determined interfacial tension, which decreases from values of 50 mN·m–1 under atmospheric conditions down to 10 mN·m–1 in CO2 but still above 30 mN·m–1 in CH4 at 10 MPa, is appropriately reflected by molecular dynamics (MD) simulations. The obtained data are analyzed in view of literature data and by using experimentally determined pressure-dependent densities and solubilities of CH4 and CO2 within ionic liquids. The results form part of a database for the ongoing development of MD simulations.
Knowledge of the thermodynamic properties of fluids and their mixtures is fundamental to the design of industrial processes. In the field of tertiary oil and gas production, significant experimental ...effort to identify properties of compressed gas mixtures has been made worldwide. Often expensive and dangerous high-pressure laboratory methods are used. Consequently, it is important to have a reliable simulation approach that allows exploratory and predictive modeling. In this work, experimental surface tension of a CO2 and CH4 mixture at elevated pressures is presented and discussed. The surface tension is an important quantity in several processes, (e.g., for describing multiphase flow). Molecular dynamics (MD) simulations are utilized to calculate the thermodynamic properties (i.e., surface tension, density, molar fractions, phase diagrams) under process-relevant conditions. MD has the potential to predict the values of these properties and provide insight into the principal behavior of the whole system. In this work, it is shown that the experimentally determined surface tension is appropriately reflected by predictive MD simulations while providing VLE densities and molar compositions of the vapor and liquid phases as additional properties in the same simulation setup.
The generation of full-sized humanized organs based on animal matrix scaffolds is a promising approach to overcome the shortage of transplant organs. Recent decellularization methods are mostly ...time-consuming and associated with large rinsing volumes and poorly standardized procedures. In this study we developed an optimized rapid and standardized decellularization method to obtain a functional porcine liver matrix within 24 h. Full porcine livers (n = 10) were decellularized by flushing with 3 L of an isotonic sodium chloride solution and controlled portal perfusion (20 mmHg) with 2 × 10 L of a 1% sodium dodecyl sulphate (SDS) solution at 37°C and a final perfusion with DNase (n = 5). Protein concentrations were continuously monitored by optical density (280 nm). DNA, glycosaminoglycans, and collagen contents were assessed and a haematoxylin and eosin (H&E) staining was performed. After 24 h of perfusion, the liver had a white and translucent appearance, and no further protein was eluted. Histological staining showed an intact extracellular matrix with no nuclear residuals. Moreover, only trace amounts of DNA were detectable in the decellularized tissue (p < 0.001), while glycosaminoglycans and about 60% of collagen levels could be preserved. Thus, we demonstrate that human-scale porcine livers can be successfully decellularized with small volumes of an SDS solution and DNase in a standardized process within 24 h to obtain a clinically relevant organ scaffold suitable for further tissue engineering.
Abstract
Surgical therapy of duodenal perforation into the retroperitoneum entails high morbidity. Conservative treatment and endoscopic negative pressure therapy have been suggested as promising ...therapeutic alternatives. We aimed to retrospectively assess outcomes of patients treated for duodenal perforation to the retroperitoneum at our department. A retrospective analysis of all patients that were treated for duodenal perforation to the retroperitoneum at our institution between 2010 and 2021 was conducted. Different therapeutic approaches with associated complications within 30 days, length of in-hospital stay, number of readmissions and necessity of parenteral nutrition were assessed. We included thirteen patients in our final analysis. Six patients underwent surgery, five patients were treated conservatively and two patients received interventional treatment by endoscopic negative pressure therapy. Length of stay was shorter in patients treated conservatively. One patient following conservative and surgical treatment each was readmitted to hospital within 30 days after initial therapy whereas no readmissions after interventional treatment occurred. There was no failure of therapy in patients treated without surgery whereas four (66.7%) of six patients required revision surgery following primary surgical therapy. Conservative and interventional treatment were associated with fewer complications than surgical therapy which involves high morbidity. Conservative and interventional treatment using endoscopic negative pressure therapy in selected patients might constitute appropriate therapeutic alternatives for duodenal perforations to the retroperitoneum.
Epigenetic alterations are a hallmark of cancer that govern the silencing of genes. Up to now, 5-azacytidine (5-aza-CR, Vidaza) and 5-aza-2'-deoxycytidine (5-aza-dC, Dacogen) are the only clinically ...approved DNA methyltransferase inhibitors (DNMTi). Current effort tries to exploit DNMTi application beyond acute leukemia or myelodysplastic syndrome, especially to solid tumors. Although both drugs only differ by a minimal structural difference, they trigger distinct molecular mechanisms that are highly relevant for a rational choice of new combination therapies. Therefore, we investigated cell death pathways in vitro in human hepatoma, colon, renal, and lung cancer cells and in vivo in chorioallantoic membrane and xenograft models. Real-time cancer cell monitoring and cytokine profiling revealed a profoundly distinct response pattern to both drugs. 5-aza-dC induced p53-dependent tumor cell senescence and a high number of DNA double-strand breaks. In contrast, 5-aza-CR downregulated p53, induced caspase activation and apoptosis. These individual response patterns of tumor cells could be verified in vivo in chorioallantoic membrane assays and in a hepatoma xenograft model. Although 5-aza-CR and 5-aza-dC are viewed as drugs with similar therapeutic activity, they induce a diverse molecular response in tumor cells. These findings together with other reported differences enable and facilitate a rational design of new combination strategies to further exploit the epigenetic mode of action of these two drugs in different areas of clinical oncology.
Current regimen to treat patients suffering from stress urinary incontinence often seems not to yield satisfactory improvement or may come with severe side effects. To overcome these hurdles, ...preclinical studies and clinical feasibility studies explored the potential of cell therapies successfully and raised high hopes for better outcome. However, other studies were rather disappointing. We therefore developed a novel cell injection technology to deliver viable cells in the urethral sphincter complex by waterjet instead of using injection needles. We hypothesized that the risk of tissue injury and loss of cells could be reduced by a needle-free injection technology. Muscle-derived cells were obtained from young male piglets and characterized. Upon expansion and fluorescent labeling, cells were injected into cadaveric tissue samples by either waterjet or injection needle. In other experiments, labeled cells were injected by waterjet in the urethra of living pigs and incubated for up to 7 days of follow-up. The analyses documented that the cells injected by waterjet in vitro were viable and proliferated well. Upon injection in live animals, cells appeared undamaged, showed defined cellular somata with distinct nuclei, and contained intact chromosomal DNA. Most importantly, by in vivo waterjet injections, a significantly wider cell distribution was observed when compared with needle injections (P < .05, n ≥ 12 samples). The success rates of waterjet cell application in living animals were significantly higher (≥95%, n = 24) when compared with needle injections, and the injection depth of cells in the urethra could be adapted to the need by adjusting waterjet pressures. We conclude that the novel waterjet technology injects viable muscle cells in tissues at distinct and predetermined depth depending on the injection pressure employed. After waterjet injection, loss of cells by full penetration or injury of the tissue targeted was reduced significantly in comparison with our previous studies employing needle injections.
PDF
