Background: Hypertrophic pyloric stenosis is the most important cause for propulsive non-bilious vomiting in infants of the first trimester. Extramucous splitting of the hypertrophic pyloric muscle is the surgical gol...Background: Hypertrophic pyloric stenosis is the most important cause for propulsive non-bilious vomiting in infants of the first trimester. Extramucous splitting of the hypertrophic pyloric muscle is the surgical gold standard for treatment. Serious major complications of pyloromyotomy (PM) are mucosal perforation and incomplete muscle splitting. The aim of the presented study is to find out if intraoperative complications are predisposed by biometric or biochemical factors. Furthermore, we looked for the influence of the board certification of the primary surgeon. Patients and Methods: 162 infants with IHPS were operated during a six-year period (n = 150 laparoscopic operations). We had 8 major complications (4.9%): iatrogenic mucosal perforation occurred in 6 cases, and incomplete PM in 2 infants. Preoperative demographic data and data resulting from the blood acid-base- and ion-analysis were compared with data of a previously published reference group from our institution (Tr?bs RB. Open J Pediatr, 2014;4: 208-215). Results: The duration of vomiting, the grade of dehydration and the severity of blood alkalosis did not differ between both groups. Furthermore, we found no influence of the gestational age and birth weight on the occurrence of intraoperative complications. It seems that early postnatal age (p = 0.07) and low body weight at surgery (p = 0.055) may contribute to surgical problems. Board certification as a paediatric surgeon did not influence the rate of intraoperative complications. Conclusions: Laboratory data did not show any predisposition to intraoperative complications. It is assumed that small infants with early occurring symptoms carry an elevated risk for intraoperative events. Our data support the hypothesis that the rate of intraoperative complications at PM is mainly influenced by skills and experience of the surgeon.展开更多
Sliding planes of PTFE are commonly used because of their excellent tribological properties. However, especially in cases of high contact pressures, PTFE suffers from its comparatively poor mechanical properties. This...Sliding planes of PTFE are commonly used because of their excellent tribological properties. However, especially in cases of high contact pressures, PTFE suffers from its comparatively poor mechanical properties. This paper presents a sliding construction developed within an innovative experimental test-setup to enable experimental investigation of large-scale concrete members subjected to punching shear. To fulfill the special demands of the new test-setup, greased, only 0.5 mm thin sheets of PTFE were used to minimize friction between the bearing construction and the test specimen. This highly effective sliding construction leads to a dynamic friction coefficient μ<sub>d,max</sub> between 0.0065 and 0.0035 while the static friction coefficient μ<sub>s</sub> remains below 0.0048. Simultaneously, compressive axial stresses of more than 60 MPa occur. The paper highlights major aspects of the sliding plane’s development and demonstrates its sliding abilities.展开更多
This paper focuses on surface metallization of oxide particles by means of titanium nitride (TiN) thin films for the production of highly wear-resistant metal matrix composites (MMC) on Fe-base for wear protection app...This paper focuses on surface metallization of oxide particles by means of titanium nitride (TiN) thin films for the production of highly wear-resistant metal matrix composites (MMC) on Fe-base for wear protection applications. These powder-metallurgically produced materials consist of a metallic matrix with embedded oxide hard-particles such as alumina or zirconia. The poor wettability of these oxides by iron-base melts and the resulting weak bonding between the components lead to porous materials and weak tribomechanical properties, thus limiting the material’s application range. To counteract such problems, this paper describes a processing route in which the oxide particles are pre-metallized by application of a thin TiN coating by means of chemical vapor deposition (CVD). This surface metallization should increase the wettability and bonding behavior between the ionically bonded particles and the iron-base alloy, which should improve the mechanical and tribological properties. Therefore, a CVD device for coating ceramic particles was constructed and is described in this paper. Furthermore, coatings deposited on the ceramic sub-strates were investigated by means of RBS, SEM and XRD. In addition, the feasibility of producing metal matrix composites (MMC) by admixing the TiN-coated oxide particles with a Fe-base alloy and their further densification by supersolidus liquid-phase sintering is demonstrated.展开更多
文摘Background: Hypertrophic pyloric stenosis is the most important cause for propulsive non-bilious vomiting in infants of the first trimester. Extramucous splitting of the hypertrophic pyloric muscle is the surgical gold standard for treatment. Serious major complications of pyloromyotomy (PM) are mucosal perforation and incomplete muscle splitting. The aim of the presented study is to find out if intraoperative complications are predisposed by biometric or biochemical factors. Furthermore, we looked for the influence of the board certification of the primary surgeon. Patients and Methods: 162 infants with IHPS were operated during a six-year period (n = 150 laparoscopic operations). We had 8 major complications (4.9%): iatrogenic mucosal perforation occurred in 6 cases, and incomplete PM in 2 infants. Preoperative demographic data and data resulting from the blood acid-base- and ion-analysis were compared with data of a previously published reference group from our institution (Tr?bs RB. Open J Pediatr, 2014;4: 208-215). Results: The duration of vomiting, the grade of dehydration and the severity of blood alkalosis did not differ between both groups. Furthermore, we found no influence of the gestational age and birth weight on the occurrence of intraoperative complications. It seems that early postnatal age (p = 0.07) and low body weight at surgery (p = 0.055) may contribute to surgical problems. Board certification as a paediatric surgeon did not influence the rate of intraoperative complications. Conclusions: Laboratory data did not show any predisposition to intraoperative complications. It is assumed that small infants with early occurring symptoms carry an elevated risk for intraoperative events. Our data support the hypothesis that the rate of intraoperative complications at PM is mainly influenced by skills and experience of the surgeon.
文摘Sliding planes of PTFE are commonly used because of their excellent tribological properties. However, especially in cases of high contact pressures, PTFE suffers from its comparatively poor mechanical properties. This paper presents a sliding construction developed within an innovative experimental test-setup to enable experimental investigation of large-scale concrete members subjected to punching shear. To fulfill the special demands of the new test-setup, greased, only 0.5 mm thin sheets of PTFE were used to minimize friction between the bearing construction and the test specimen. This highly effective sliding construction leads to a dynamic friction coefficient μ<sub>d,max</sub> between 0.0065 and 0.0035 while the static friction coefficient μ<sub>s</sub> remains below 0.0048. Simultaneously, compressive axial stresses of more than 60 MPa occur. The paper highlights major aspects of the sliding plane’s development and demonstrates its sliding abilities.
文摘This paper focuses on surface metallization of oxide particles by means of titanium nitride (TiN) thin films for the production of highly wear-resistant metal matrix composites (MMC) on Fe-base for wear protection applications. These powder-metallurgically produced materials consist of a metallic matrix with embedded oxide hard-particles such as alumina or zirconia. The poor wettability of these oxides by iron-base melts and the resulting weak bonding between the components lead to porous materials and weak tribomechanical properties, thus limiting the material’s application range. To counteract such problems, this paper describes a processing route in which the oxide particles are pre-metallized by application of a thin TiN coating by means of chemical vapor deposition (CVD). This surface metallization should increase the wettability and bonding behavior between the ionically bonded particles and the iron-base alloy, which should improve the mechanical and tribological properties. Therefore, a CVD device for coating ceramic particles was constructed and is described in this paper. Furthermore, coatings deposited on the ceramic sub-strates were investigated by means of RBS, SEM and XRD. In addition, the feasibility of producing metal matrix composites (MMC) by admixing the TiN-coated oxide particles with a Fe-base alloy and their further densification by supersolidus liquid-phase sintering is demonstrated.