Publications by authors named "Dietmar Stephan"

Introduction: Inguinal hernia repair (IHR) is one of the most common procedures in pediatric surgery. In children, the application of robotic surgery is limited, meaning safety and efficacy is still to be assessed. This report is the first one worldwide that describes inguinal hernia repair in children using the Senhance Surgical System (SSS).

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This paper presents the results of the optimisation and characterization of Miscanthus fibre reinforced geopolymer foams based on fly ash and represents an important step forward in the development of a sustainable and environmentally friendly insulation material. Miscanthus belongs to a promising group of renewable raw materials with favourable thermal insulation properties. Design of experiment (DoE) were used to optimize the thermal conductivity and compressive strength of e reinforced geopolymer foams.

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Low-vacuum scanning electron microscopy (low-vacuum SEM) is widely used for different applications, such as the investigation of noncoated specimen or the observation of biological materials, which are not stable to high vacuum. In this study, the combination of mineral building materials (concrete or clay plaster) with a biological composite (fungal mycelium composite) by using low-vacuum SEM was investigated. Fungal biotechnology is increasingly gaining prominence in addressing the challenges of sustainability transformation.

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The Senhance Robotic System™ (Asensus Surgical, Durham, NC, USA) has been used in abdominal surgery since 2016, and provides an eye-tracker for camera movement and haptic tactile feedback. Safety aspects are very important in robotic surgery, such as regarding the presence of system malfunctions and surgical outcomes. The data for robotic function in gastrointestinal surgical procedures in 530 patients (colorectal surgery, fundoplication, others) were prospectively listed in the TRUST registry after informed patient consent in three German gastrointestinal surgery centers (center A, N = 46 patients; center B, N = 457; center C, N =27).

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Many research articles and reviews have recognized alkali-activated materials (AAMs) as eco-friendly alternative binders to ordinary Portland cement (OPC) due to their economic andenvironmental advantages. However, few literature surveys reported the physical, mechanical and microstructural changes that occur after the exposure of AAMs to elevated temperatures. Owing to the wide diversity in the properties of aluminosilicates, alkali-activation conditions, and additives, a deep survey is needed to understand how different factors can affect the performance of AAMs under elevated temperatures.

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The symptoms of gastroesophageal reflux disease (GERD) are very common, but cannot be reliably controlled with medication, as more than 40% of patients suffer troublesome symptoms more than twice a week even when taking maximum doses of proton pump inhibitors (PPI). Until recently, the only surgical option was anti-reflux surgery, usually performed as a hiatal hernia repair and some form of fundoplication. While this is still the gold standard, some centers note high recurrence rates and/or high rates of side effects such as dysphagia, bloating, and post-prandial discomfort.

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Introduction: The ArtiSential® line of products from LivsMed (Seongnam, Republic of Korea) are fully articulated hand-held laparoscopic instruments, possessing end-effectors that closely imitate those of surgical robots with regard to shape and dexterity. Feasibility and safety studies describing the initial experiences with these devices in upper and lower gastrointestinal as well as thoracic surgery have been published. This report presents the outcomes of the largest cohort to date of colorectal procedures performed with Artisential® instruments in a single center.

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A pediatric robotic pyeloplasty has been performed with the Senhance robotic system for the first time in January 2021 on a 1.5-year-old girl with symptomatic ureteropelvic junction stenosis. A Senhance robotic system (Asensus Surgical Inc.

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The Sr/Sr isotope ratio can, in principle, be used for provenancing of cement. However, while commercial cements consist of multiple components, no detailed investigation into their individual Sr/Sr isotope ratios or their influence on the integral Sr/Sr isotope ratio of the resulting cement was conducted previously. Therefore, the present study aimed at determining and comparing the conventional Sr/Sr isotope ratios of a diverse set of Portland cements and their corresponding Portland clinkers, the major component of these cements.

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Purpose: The advent of robotic surgery has highlighted the advantages of articulation. This dry-lab study examined the dexterity and learning effect of a new articulated laparoscopic instrument: the ArtiSential® forceps (LIVSMED, Seongnam, Republic of Korea).

Methods: A peg board task was designed.

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Introduction: Robotic surgery was first introduced in the mid-1980s, and at the end of the '90s, the da Vinci® System (Intuitive Surgical Inc., Sunnyvale, California) was introduced in Europe and held a monopoly for years afterward. In 2016, Senhance™ digital laparoscopic platform (TransEnterix Inc.

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In order to determine the potential environmental impact of construction products, it is necessary to evaluate their influence on organisms exposed to them or their eluates under environmental conditions. The behavior of the white worm is a useful tool for assessing the potential environmental impact of construction products in contact with water and soil. This study investigates the environmental effects of eluates from two construction products, a reactive waterproofing product, and an injection resin, on the reproduction and avoidance behavior of .

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Introduction: While the well-known DaVinci ® robotic system (Intuitive Surgical, Inc., Sunnyvale, CA) uses 8 mm articulated instruments, the Senhance ® robotic system (TransEnterix, Morrisville, NC), available since 2016, uses 5 mm instruments, which is the standard size in laparoscopy. We report here the first 43 procedures using 5 mm articulating instruments with the Senhance ® system (TransEnterix).

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The effect of styrene-acrylate (SA) polymer latex on alkali-activated slag (AAS) was systematically studied in the aspects of hydration, hydration products, pore structure and mechanical properties through the combined analytical techniques including calorimetry, X-ray diffraction, thermogravimetric analysis, mercury intrusion porosimetry, and mechanical measurement. It was found that the addition of SA does not retard the AAS hydration, but slightly accelerates it, possibly due to the increasing ion diffusion through the loosely structured hydration products. Pore structure analysis indicates that the addition of polymer increases the cumulative pore volume and the portion of pores with size >100 nm in the hardened AAS paste.

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The development of sustainable, environmentally friendly insulation materials with a reduced carbon footprint is attracting increased interest. One alternative to conventional insulation materials are foamed geopolymers. Similar to foamed concrete, the mechanical properties of geopolymer foams can also be improved by using fibers for reinforcement.

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The performance of vacuum insulation panels (VIPs) is strongly affected by several factors, such as panel thickness, design, quality of vacuum, and material type. In particular, the core materials inside VIPs significantly influence their overall performance. Despite their superior insulation performance, VIPs are limited in their widespread use as structural materials, because of their low material strength and the relatively expensive core materials.

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The interaction of different charged polymers, namely anionic polycarboxylate superplasticizer (PCE) and neutral polyethylene glycol (PEG) with potassium ions, and their effect on the yield stress of highly concentrated glass bead suspension (GBS), were studied under different concentrations of potassium ions ([K]). It was found that, compared to the neutral PEG, the negatively charged PCE can be adsorbed on glass beads (GB), and then decreases the yield stress of GBS. The increasing concentration of free polymer in the interstitial liquid phase with the increased polymer dosage leads to the higher yield stress of GBS, which may be caused by the higher depletion force.

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The rheological behavior of cement paste and the improvement of its flowability takes center stage in many research projects. An improved flowability can be achieved by the addition of superplasticizers (SP), such as polycarboxylate ethers (PCE). In order to be able to use these PCEs effectively and in a variety of ways and to make them resistant to changes in the environment, it is crucial to understand the influence of SPs on cement hydration.

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In this paper, studies of the mechanical properties and photocatalytic activity of new photoactive cement mortars are presented. The new building materials were obtained by the addition of 1, 3, and 5 wt % (based on the cement content) of nitrogen-modified titanium dioxide (TiO/N) to the cement matrix. Photocatalytic active cement mortars were characterized by measuring the flexural and the compressive strength, the hydration heat, the zeta potential of the fresh state, and the initial and final setting time.

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In order to gain a deeper understanding of the rheological development of hydrating ordinary Portland cement (OPC) pastes at initial state, and to better understand their underlying processes, quantitative X-ray diffraction (XRD) analysis and rheological measurements were conducted and their results combined. The time-dependent relation between phase development and flow behavior of cement paste was investigated at two different temperatures (20 and 30 °C), over a period of two hours. Regarding the phase development during hydration, ettringite precipitation was identified as the dominant reaction in the first two hours.

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This study presents the results of an experimental investigation of the effects of nanosilica (NS) on the strength development, transport properties, thermal conductivity, air-void, and pore characteristics of lightweight aggregate concrete (LWAC), with an oven-dry density <1000 kg/m. Four types of concrete mixtures, containing 0 wt.%, 1 wt.

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For the past 70 years, researchers have dealt with the investigation of odour in sewer systems caused by hydrogen sulphide formations and the development of approaches to describe it. The state-of-the-art models are one-dimensional. At the same time, flow and transport phenomena in sewers can be three-dimensional, for example the air flow velocities in circular pipes or flow velocities of water and air in the reach of drop structures.

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Introduction: This retrospective study was performed to evaluate the safety and feasibility of the new Senhance Robotic System (TransEnterix Inc., Morrisville, North Carolina) for inguinal hernia repairs using the transabdominal preperitoneal approach.

Materials And Methods: From March to September 2017, 76 inguinal hernia repairs in 64 patients were performed using the Senhance Robotic System.

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Exposure to elevated temperatures has detrimental effects on the properties of cementitious composites, leading to irreversible changes, up to total failure. Various methods have been used to suppress the deterioration of concrete under elevated temperature conditions. Recently, nanomaterials have been introduced as admixtures, which decrease the thermal degradation of cement-based composites after exposure to high temperatures.

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