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Background: Clinical and experimental data indicate that neonates are sensitive to the CO2 pneumoperitoneum. An impaired splanchnic perfusion during laparoscopy in adults has been reported. We recently confirmed that intravenous colloids improve macrocirculatory function in neonates. We aimed to determine the impact of CO2 pneumoperitoneum on the perfusion of splanchnic organs in the young including effects of colloid application.Methods: Male piglets (n = 25) were divided into four groups: (1) neonatal controls, (2) neonates with crystalloid restitution, (3) neonates with colloidal restitution, and (4) adolescents with crystalloid restitution. Animals were ventilated and subjected to a 3-h, 10 mmHg CO2 pneumoperitoneum followed by 2 h resuscitation. Hepatic, splanchnic, and arteriovenous shunt perfusion was assessed via central and portal venous catheters. Capillary organ flow was detected by fluorescent microspheres. The rate of bile flow was measured.Results: The neonatal crystalloid group showed a significant decrease in the intestinal capillary perfusion at the end of the recovery period. This was not detectable in the adolescent and colloid group. There was a significant increase in microcirculatory arterioportal shunt flow during the CO2 pneumoperitoneum in both neonatal groups but not in the sham and adolescent groups (p < 0.05). Hepatic arterial perfusion increased after insufflation in all groups and dropped during capnoperitoneum to levels of about 70% baseline. There was no significant impairment of splanchnic perfusion or bile flow as a result of the pneumoperitoneum in all groups.Conclusions: Capillary perfusion of the abdominal organs was stable during capnoperitoneum and recovery in adolescents and neonates with colloid restitution, but not with crystalloid restitution. Significant arterioportal shunting during capnoperitoneum could affect hepatic microcirculation in neonates. Our data confirm that moderate pressure capnoperitoneum has no major effect on the perfusion of abdominal organs in neonates with adequate substitution. [ABSTRACT FROM AUTHOR]

Purpose: Acute respiratory distress syndrome, with the need for invasive mechanical ventilation (MV) remains a major cause of neonatal mortality and morbidity. Although venovenous extracorporeal lung support (VV-ECLS) has become a standard of care procedure in neonatal patients with acute pulmonary failure there are no reports regarding the use of a double-lumen cannula for extracorporeal minimal invasive lung support via the umbilical vein.Methods: A neonatal lamb model was used (n = 3). Umbilical vein was cannulated with a double-lumen catheter allowing venovenous extracorporeal gas exchange. Cannula was positioned with its tip in the right atrium. VV-ECLS was started and ventilation was stopped. Providing oxygenation and CO2 removal solely through VV-ECLS hemodynamics, blood gases were measured.Results: Total VV-ECLS without MV was applied to all three neonatal lambs. Time on venovenous ECLS was 60, 120 and 120 min. Initial pCO2 was 60, 56 and 65 mmHg compared to 31, 32 and 32 mmHg at the end of VV-ECLS. Initial pO2 was 30, 27 and 26 mmHg compared to 22, 19 and 23 mmHg. Initial lactate was 5, 10 and 3.7 mmol/l compared to 13.3, 12.6 and 11.3 mmol/l at the end of VV-ECLS. MAP at baseline was 51, 52 and 65 mmHg compared to 36, 38 and 41 mmHg at the end of VV-ECLS. In all three lambs inotropes were admitted to maintain MAD >35 mmHg.Conclusion: Even without mechanical ventilation we were able to sufficiently remove pCO2 with our new minimal invasive VV-ECLS using a double-lumen catheter via the umbilical vein, supporting the idea of a lung protective strategy in neonatal acute respiratory failure. pO2 was measured 22, 19 and 23 mmHg, respectively, at the end of VV-ECLS, at least partially caused by recirculation phenomenon, which could possibly be improved by different cannula design. Inotropic support was necessary during VV-ECLS to achieve targeted MAD > 35 mmHg. While technically feasible, this new approach might allow further research in the field of extracorporeal lung support and therefore will follow the concept of a lung protective strategy in acute neonatal respiratory failure. [ABSTRACT FROM AUTHOR]

Introduction: Aim of the study was to carry out a 5-year survey of German patients with biliary atresia (BA) and to launch a discussion regarding the feasibility of voluntary registries in unregulated healthcare systems. Methods: A retrospective analysis of German BA patients born between 2001 and 2005, based on data collected from the voluntary European Biliary Atresia Registry (EBAR), was carried out and supplemented by data from all BA patients who underwent liver transplantation at the only 4 pediatric transplantation centers (pLTx) in Germany which are so far not registered at EBAR. Survival rates were calculated using Kaplan- Meier analysis and compared by Cox regression to determine the predictive value of age at surgery and the influence of the center size (fewer or more than 5 patients / study period) on overall survival and survival with native liver. Results: A critical review of the 148 German EBAR charts revealed that 11 patients (7.4 % ) had no biliary atresia. The remaining 137 patients from EBAR together with 46 BA patients who underwent LTx without prior registration at EBAR were evaluated with a median follow-up of 39 months (range: 25 - 85 months). 29 hospitals performed a total of 159 Kasai procedures, but only 7 centers treated 5 or more patients (116 patients, range: 5 - 68), and 22 hospitals performed less than 5 KP (43 patients, range: 1 - 4). Primary LTx was performed in 21 patients (11.5 % ) and 3 patients died without surgical intervention. 16 patients were lost to follow-up (8.7 % ). Overall survival after 2 years was 83.3 % (139 patients), including 105 patients (63 % ) who had undergone LTx and 34 patients (20.3 % ) with native liver. 28 patients died (16.7 % ), 8 after LTx (5.8 % ). The experience of the center was the only factor with a significant predictive value for jaundice- free survival with native liver (p = 0.001). Conclusion: 25 % of all German BA patients were not registered at EBAR, and 29 clinics were involved in the surgical management of BA patients. Therefore a new approach consisting of an internet-based decentralized registry for rare neonatal liver diseases is outlined which could improve the future management of patients with BA. The centralization of such patients at experienced centers with higher caseloads is necessary in Germany and would improve the outcome of patients with biliary atresia. [ABSTRACT FROM AUTHOR]

Introduction: Aim of the study was to carry out a 5-year survey of German patients with biliary atresia (BA) and to launch a discussion regarding the feasibility of voluntary registries in unregulated healthcare systems. Methods: A retrospective analysis of German BA patients born between 2001 and 2005, based on data collected from the voluntary European Biliary Atresia Registry (EBAR), was carried out and supplemented by data from all BA patients who underwent liver transplantation at the only 4 pediatric transplantation centers (pLTx) in Germany which are so far not registered at EBAR. Survival rates were calculated using Kaplan-Meier analysis and compared by Cox regression to determine the predictive value of age at surgery and the influence of the center size (fewer or more than 5 patients/study period) on overall survival and survival with native liver. Results: A critical review of the 148 German EBAR charts revealed that 11 patients (7.4%) had no biliary atresia. The remaining 137 patients from EBAR together with 46 BA patients who underwent LTx without prior registration at EBAR were evaluated with a median follow-up of 39 months (range: 25–85 months). 29 hospitals performed a total of 159 Kasai procedures, but only 7 centers treated 5 or more patients (116 patients, range: 5–68), and 22 hospitals performed less than 5 KP (43 patients, range: 1–4). Primary LTx was performed in 21 patients (11.5%) and 3 patients died without surgical intervention. 16 patients were lost to follow-up (8.7%). Overall survival after 2 years was 83.3% (139 patients), including 105 patients (63%) who had undergone LTx and 34 patients (20.3%) with native liver. 28 patients died (16.7%), 8 after LTx (5.8%). The experience of the center was the only factor with a significant predictive value for jaundice-free survival with native liver (p=0.001). Conclusion: 25% of all German BA patients were not registered at EBAR, and 29 clinics were involved in the surgical management of BA patients. Therefore a new approach consisting of an internet-based decentralized registry for rare neonatal liver diseases is outlined which could improve the future management of patients with BA. The centralization of such patients at experienced centers with higher caseloads is necessary in Germany and would improve the outcome of patients with biliary atresia. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the failure of one particular design of component used in the production of ceramic bracelets for watches. A ceramic bracelet is made up of many ceramic “links”. The ceramic link components are interconnected using a metal skeletal frame to produce the bracelet. However, in service a number of the ceramic link components experienced fracture and subsequently failure. A systematic failure analysis was performed to characterize the different types of failure mechanism and to determine the cause of the failures. Initial examination was followed by detailed characterization using optical and scanning electron microscopy. The size of the fracture origins which were found were then verified by calculations based on the Griffith equation. Failure analysis indicated that significantly large defects were introduced into the components during the injection moulding. The results, conclusions and recommendations of this study are presented. [Copyright &y& Elsevier]

Background: The definite clinical diagnosis of acquired neonatal intestinal diseases (ANID) is a challenge, usually met by applying Bell's or, more recently, Gordon's classification. Both classifications incorporate radiological pneumatosis intestinalis (PI) as a cornerstone of the NEC diagnosis. However, PI may be absent or difficult to identify by abdominal X-ray. Portal venous gas detected by ultrasound (PVG-US) has been proposed as another characteristic of NEC, but its incidence in other entities of ANID remains unknown. Objective: To determine whether PVG-US and Gordon ' s classification can help to differentiate between NEC and other ANID, especially SIP. Methods: Retrospective analysis of the data of 83 infants, who underwent laparotomy for a clinical diagnosis of ANID was performed. The results of PVG-US and other markers of ANID were compared with the operative result, defined as the gold standard for diagnosis. Results: The NEC diagnosis was confirmedh in 28/83 infants and PVG-US was present in 23 (82 %) of those patients prior to operation. PVGUS was detected in 2 patients without NEC (one volvulus, one SIP), resulting in an 82 % sensitivity and a 96 % specificity. The sensitivity and specificity of radiological PI for patients with NEC was lower (75 and 91 %), but the combination of PVGUS and radiological PI increased the sensitivity for NEC detection to 89 % . Gordon ' s classification had a sensitivity of 93 % and a specificity of 92 % for NEC diagnosis. Conclusion: Screening for PVG-US and Gordon ' s classification are valid tools to differentiate between NEC and other ANID including SIP. Although an effect of these proposed diagnostic tools on treatment regimen and operative management has yet to be verified, the improvement in diagnosing ANID is certainly valuable. [ABSTRACT FROM AUTHOR]

Background: The definite clinical diagnosis of acquired neonatal intestinal diseases (ANID) is a challenge, usually met by applying Bell's or, more recently, Gordon's classification. Both classifications incorporate radiological pneumatosis intestinalis (PI) as a cornerstone of the NEC diagnosis. However, PI may be absent or difficult to identify by abdominal X-ray. Portal venous gas detected by ultrasound (PVG-US) has been proposed as another characteristic of NEC, but its incidence in other entities of ANID remains unknown. Objective: To determine whether PVG-US and Gordon's classification can help to differentiate between NEC and other ANID, especially SIP. Methods: Retrospective analysis of the data of 83 infants, who underwent laparotomy for a clinical diagnosis of ANID was performed. The results of PVG-US and other markers of ANID were compared with the operative result, defined as the gold standard for diagnosis. Results: The NEC diagnosis was confirmed in 28/83 infants and PVG-US was present in 23 (82%) of those patients prior to operation. PVG-US was detected in 2 patients without NEC (one volvulus, one SIP), resulting in an 82% sensitivity and a 96% specificity. The sensitivity and specificity of radiological PI for patients with NEC was lower (75 and 91%), but the combination of PVG-US and radiological PI increased the sensitivity for NEC detection to 89%. Gordon's classification had a sensitivity of 93% and a specificity of 92% for NEC diagnosis. Conclusion: Screening for PVG-US and Gordon's classification are valid tools to differentiate between NEC and other ANID including SIP. Although an effect of these proposed diagnostic tools on treatment regimen and operative management has yet to be verified, the improvement in diagnosing ANID is certainly valuable. [ABSTRACT FROM AUTHOR]

Long-lasting minimally invasive procedures are increasingly used for children. However, the hemodynamic effects of a prolonged carbon dioxide (CO2) pneumoperitoneum (PP) on small infants are poorly understood and may differ from the effects on adolescents. This study aimed to detect and compare these effects in neonatal and adolescent pigs. Six neonatal pigs weighing 5.6–6.4 kg and six adolescent pigs weighing 51–57 kg underwent a prolonged CO2 PP of 180 min. Five neonatal pigs weighing 5.7–6.6 kg underwent sham PP as an additional control group. All the animals received crystalloid electrolyte solution at 10 ml/kg/h during the experiments. After CO2 decompression, all the animals were monitored for a further 120 min. The end points of the study were mean arterial pressure (MAP), central venous pressure (CVP), and cardiac index (CI). The parameters were assessed after a 60-min resting phase (i.e., after initial placement of catheters in the jugular vein, the carotid artery, and the femoral artery four times during CO2 PP and three times afterward. The comparison of neonates and adolescent pigs showed that neonates had a significantly more pronounced decrease in MAP during CO2 PP (88.1 ± 2.7% of baseline vs 95.1 ± 1.6%; p < 0.05) and the recovery period (71 ± 5.1% vs 86.4 ± 1.4%; p < 0.05). Differences in CVP changes between the neonatal and adolescent pigs during and after CO2 PP were not significant. For the neonates, the decrease in CI was most pronounced during the recovery period after decompression of the CO2 PP and significantly less than in adolescents (84.3 ± 3.3% of baseline vs 97.4 ± 4.5%; p < 0.05). The neonates with sham PP did not show any significant MAP, CVP, or CI changes during the experiments. A prolonged CO2 PP induces hypotension and cardiac depression in neonatal but not in adolescent pigs. Thus, intensive monitoring during prolonged laparoscopic procedures and particularly afterward may be mandatory for neonates. [ABSTRACT FROM AUTHOR]

Caudal anesthesia (CA) is widely recommended due to excellent analgesia in distal hypospadia repairs, but its potential side effect on urinary retention interferes with patient comfort. To objective is to determine the impact of CA versus penile block (PB) on postoperative micturition. Sixty distal hypospadia repairs performed over a 48-month period were analyzed concerning the impact of applicated analgesia on postoperative micturition. Inclusion criteria were Mathieu or Snodgrass procedures, use of a non-dribbling urethral stent, CA or PB. Endpoint was first postoperative micturation (<6 h), or treatment of delayed postoperative micturation (>6 h). CA was used in 27 and PB in 33 cases. Compared groups had similar age (mean: 31 months, range 12–68 vs. 28 months, range: 14–145), weight (mean: 13 kg, range 9–18 vs. 15 kg, range 8–59), operation duration (mean 61 min, range 30–105 vs. mean 67 min, range 35–120) and surgical technique (Mathieu/Snodgrass: 7/20 CA vs. 19/14 PB). Micturation was significantly less impaired in the PB than CA group (5/33 vs. 15/27; p < 0.05). Delayed or non-micturation was successfully treated in 4 and 14 patients, respectively, by cholinergic agonists. One patient of each group required a suprapubic drain on the first operative day after unsuccessful medical treatment. In our series, children undergoing distal hypospadia repair experienced significantly less impaired micturition when using penile block instead of caudal anesthesia. We recommend penile block as the first choice perioperative analgesia, when spontaneous postoperative micturition must be guaranteed. [ABSTRACT FROM AUTHOR]

Background: Minimally invasive techniques are increasingly used for biopsy and resection of neuroblastoma, but the impact on the behavior of spilled tumor cells is unknown. We aimed to investigate whether CO(2) pneumoperitoneum can affect local or systemic tumor manifestation after spillage of neuroblastoma cells into the peritoneal cavity.Methods: Murine neuroblastoma cells (Neuro2a, 1x10(6)) were inoculated into the peritoneal cavity of 25 male A/J mice, which subsequently underwent CO(2) pneumoperitoneum (n = 12) or laparotomy (n = 13) for 1 h. At the 28th postoperative day, local (peritoneal and surface of the gut) and systemic (liver, lung, spine) tumor spread was graded in a blinded manner (1-4 point scale) and specimens were histologically examined for tumor manifestation (hematoxylin and eosin stain) and tumor cell proliferation rate (Ki-67-stain). In the case of no visible lesion, five random sections were histologically examined. Peritoneal carcinosis was graded macroscopically.Results: Tumor manifestations were detected in 10 out of 12 (83%) animals after CO(2) pneumoperitoneum, and in 9 out of 13 (69%) after laparotomy (n.s.). Incidence of liver metastasis was higher after CO(2) pneumoperitoneum versus laparotomy (83% versus 31%; p < 0.05). Incidence and grading of peritoneal carcinosis was not significantly different between the groups (n.s.). Intrapulmonary metastasis was found in one mouse of each group, but no metastasis of the spine. However, the grading of liver metastasis was higher after CO(2) pneumoperitoneum compared to laparotomy (p < 0.05). Tumor cell proliferation (Ki-67 stain) in the liver did not differ between both groups. Moreover, proliferation always exceeded 50% of tumor cells, irrespective local or systemic tumor manifestation.Conclusions: CO(2) pneumoperitoneum increased intrahepatic metastasis, but not local peritoneal carcinosis in a murine neuroblastoma model. This suggests that laparoscopy could promote systemic dissemination of intraperitoneally spilled tumor cells when no chemotherapy is applied. It remains to be determined whether this is due to local immune suppression or direct modulation of tumor cell behavior. [ABSTRACT FROM AUTHOR]

Abstract: Aluminum–micro-cellular SiOC ceramic foams dense composites were prepared, in which the cell size was varied at a constant metal volume fraction and their mechanical properties were evaluated. Very limited interfacial reaction was observed between the ceramic and metal phases. A reduction of the pore former size from 50 to10μm improved the Brinell hardness, the yield strength (>20%), the ultimate tensile strength (>60%) and the elongation tolerance of the composite (50%). This work shows the benefit of using micro-cellular ceramic foams for the production of metal matrix composites, as their larger (geometric) surface area, as compared to conventional open ceramic foams reinforcement, affords improved mechanical interlock and interfacial reaction with the metal phase. [Copyright &y& Elsevier]

The article focuses on the development of severe enteropathy among patients with stage II/III colon cancer undergoing adjuvant therapy based on a clinical trial in the U.S. The patients were treated with weekly bolus 5-fluorouracil (5-FU) and leucovorin with or without oxalipatin. About 4.3% of the patients developed a syndrome of bowel wall injury (BWI) and 22 patients treated with leucovorin with oxaliplatin developed enteric sepsis (ES). There were 5 deaths due to enteropathy and 3 related to both BWI and ES.

Background: The improved outcome after endoscopic surgery has been attributed to less surgical trauma. However, the underlying mechanisms are not fully understood, and direct effects of CO2 used for pneumoperitoneum, cellular acidification, and/or the lack of air contamination have been postulated to additionally modulate immune functions during endoscopic surgery. We investigated the effects of CO2 incubation, extracellular acidification, and air contamination on the inflammatory response of two distinct macrophage populations. Methods: R2 and NR8383 rat macrophage cell lines were used. Interleukin-6 (IL-6) and nitric oxide after lipopolysaccharide (LPS) stimulation were determined in these sets of experiments: incubation in 100% CO2, 5% CO2, and room air for 2h; incubation at pH 7.4, 6.5, and 5.5 for 2 h in 5% CO2; and incubation in 100% CO2, 5% CO2 and room air in fixed pH 6.3. The extracellular pH was monitored during incubation. We determined the alteration of intracellular pH in cells subjected to extracellular acidification by fluorescence microscopy. Results: Extracellular pH decreased to 6.3 during 100% CO2 incubation. IL-6 release was reduced after CO2 incubation inNR8383 cells and increased inR2cells (p < 0.05). It was not altered by air incubation. Decreasing the extracellular pH to 6.5 mimicked the effects of CO2 and a decrease to 5.5 suppressed IL-6 release in both cell lines. In fixed pH at 6.3, CO2 and air incubation had no effect. CO2 and pH had no impact on nitric oxide release and vitality. Intracellular pH decreased with extracellular acidification without significant difference between the two cell lines. Conclusions: A decrease in extracellular pH during incubation in CO2 differentially affects IL-6 release in macrophage subpopulations. This may explain contradictory results in the literature. Moreover, we demonstrated that air contamination does not affect macrophage cytokine release. The decrease in extracellular pH is the primary underlying mechanism of the alteration of macrophage cytokine release after CO2 incubation, and it appears that the ability to maintain intracellular pH is not determined by the effects of CO2 or extracellular acidification. [ABSTRACT FROM AUTHOR]

Ceramic laminates with strong interfaces between layers are considered a very promising material for different engineering applications because of the potential for increasing fracture toughness by designing high residual compressive and low residual tensile stresses in separate layers. In this work, Si3N4/Si3N4-TiN ceramic laminates with strong interfaces were manufactured by rolling and hot pressing techniques. The investigation of their mechanical properties has shown that the increase in apparent fracture toughness can be achieved for the Si3N4/Si3N4-20 wt.%TiN composite, while further increase of TiN content in the layers with residual tensile stresses lead to a formation of multiple cracks, and as a result, a significant decrease in the mechanical performance of the composites. Micro-Raman spectroscopy was used to measure the frequency shift across the Si3N4/Si3N4-20 wt.%TiN laminate. These preliminary Raman results can be useful for further analysis of residual stress distribution in the laminate. [ABSTRACT FROM AUTHOR]

Abstract: Graphite/aluminium composites with an interpenetrating network microstructure were produced by the indirect squeeze casting process. Porous isotropic graphite preforms with about 14.5vol.% porosity were infiltrated either with AlSi7Ba or AlSi12. Flexural strength and fracture toughness were determined at room temperature and 300°C before and after thermal cycling. The composites exhibit a significantly higher mechanical strength and fracture toughness than the graphite preforms. The infiltration with aluminium alloys enhances the flexural strength by a factor of two up to about 120MPa and increases the fracture toughness from 0.94 to 1.93MPam1/2. At 300°C, no decrease in flexural strength of the composites is observed. Thermal cycling results in a slight reduction of the mechanical properties for graphite/AlSi7Ba composites, while graphite/AlSi12 composites show no decline in strength and toughness, respectively. The effect of aluminium composition and thermal cycling on the mechanical properties are explained by means of a crack bridging model. [Copyright &y& Elsevier]

An episode selection procedure was developed and applied to select sets of days representing characteristic meteorological conditions leading to high ozone episodes over the Swiss Plateau. The selection procedure was applied to data extending from January 1991 through December 1998, and is comprised of two steps: First, days were classified according to observed air quality and meteorological characteristics using classification and regression trees analysis (CART). Second, the CART results were used in conjunction with observed air quality data to identify sets of days characteristic of those leading to elevated ozone. These sets of days were selected to optimise how well a limited number of days represented seasonal air quality, and that formed longer episodes for use in the air quality modelling. CART analysis was performed for three zones of the Swiss Plateau that have different air quality and meteorological characteristics. The results for two zones were used together in the episode selection procedure in order to identify days representative for the whole Plateau. Meteorological analysis for a third zone suggested that it would be strongly impacted by pollutants transported in from outside the country. One thousand and eight hundred optimisation runs were performed to minimise the likelihood that the set of days was a local optimum, increasing the robustness for use in air quality modelling analysis. Fifteen days, grouped in four episodes ranging from 3 to 5 days were selected along with their calculated representativeness (or weight) to recreate a seasonal metric. The variety of local as well as regional meteorological characteristics showed that the episode selection procedure chose days representing a diverse set of meteorological situations which are associated with elevated ozone. This set of episodes can now be used to test air quality strategies. [Copyright &y& Elsevier]

Myeloproliferative disorders are variable disorders, based on the genetic abnormality present and the cell line progenitors that are affected. In this case, we discuss a novel gene translocation in the subset of PDGFRB mutations, first seen with prominent hyperbasophilia. This case demonstrates the possibility for lower therapeutic doses of imatinib mesylate than previously reported, in order to control leukocyte counts and reverse the genetic mutation. [ABSTRACT FROM AUTHOR]

Abstract Free standing single layer silicon carbonitride components with sub-mm features have been constructed by maskless lithography followed by pyrolysis. In comparison to prior fabrication methods based on molding of ceramic precursors, this work is advantageous as crosslinked polymer green bodies are formed in a direct manner and no mold is needed. The resultant silazane green bodies are pyrolyzed in argon to give SiCN ceramics. Mechanical properties of test samples created via the same process indicate typical flexural strength of 890 MPa and hardness of 1550 HV 1.0. This methodology should be of general interest for the production of silicon carbide and silicon carbonitride components for various MEMS applications. [ABSTRACT FROM AUTHOR]

Abstract: Computed X-ray tomography was used to characterise distribution and sphericity of Ti granules within highly porous (>35%) Al2O3 powder compacts, as they are key parameters for a successful infiltration by Fe-based alloys. Setting of reconstruction constraints, image editing as well as data processing are the most challenging parts of computed X-ray tomography and principal sources of errors that bias the generated data. Thus, corrective measures have to be applied and the reliability of generated data has to be proved with respect to statistical, stereological and volumetric aspects. Combining an adapted Interface Particle Treatment Algorithm with the Marching Cube Method, Equilibrium Random State Model, cluster splitting and conventional laser diffraction measurements a significant improvement of the three-dimensional reconstructed data was achieved. This study points out the need of the applied algorithms for the proof and improvement of generated data by computed X-ray tomography and gives a short survey of methods that can be applied. [Copyright &y& Elsevier]

Carboplatin/docetaxel chemotherapy was evaluated in advanced squamous cell carcinoma of the head and neck (SCCHN). Eligibility included patients with recurrent, persistent, or metastatic SCCHN with Zubrod performance status 0-2. Docetaxel 65 mg/m2 and carboplatin (AUC of 6) were given IV in a 21-day cycle to 68 patients. Response probability was 25 percent (95%CI: 15-38). The major toxicity observed was neutropenia, with 36 patients (61 percent) experiencing Grade 3 or worse. Median progression-free survival was 3.8 months (95%CI, 3.1-4.8) Median overall survival was 7.4 months (95%CI, 6.2-8.9). The results of this study suggest this regimen is active for outpatient treatment of recurrent SCCHN patients with good performance status. [ABSTRACT FROM AUTHOR]

Abstract: Metal matrix composites (MMC) were produced by activated pressureless melt infiltration. Ti-activated pressed Al2O3 powder compacts were infiltrated with several Fe-base or Ni-base alloys to investigate the influence of single alloying elements on the infiltration process and the resulting MMC structure. While it was found that there are minor differences in the infiltration behaviour of the single alloys, infiltration quality and the obtained MMC microstructures were more strongly influenced by the initial activator amount and the dwell time of the process than by the infiltrate itself. Fe-base alloys as well as Ni-base alloys were found suitable for Ti-activated melt infiltration using Al2O3 ceramic. [Copyright &y& Elsevier]

Active metal brazing is a widely used technique for joining of advanced ceramics to metals. Two Ti-activated brazes have been investigated for joining of a Si3N4/TiN ceramic composite to steel. A commercially available braze CB6 (Ag 98.4%, In 1%, Ti 0.6% from Degussa) has been compared with a CuSnTiZr alloy. In addition, the properties of a two-layered brazing filler system with and without WC particle reinforcement have been investigated. In the present study, standard 4-point flexural strength testing of brazed joints is combined with a detailed fractographic study to determine the causes of failure in the different systems. In the best systems, an average bending strength of 466 MPa was achieved when joining ceramic to ceramic and 398 MPa when joining ceramic to metal. [Copyright &y& Elsevier]

Purpose: A growing body of research suggests that inflammation plays a role in many chemotherapy-related toxicities such as fatigue, anxiety, and neuropathy. Regular exercise can change levels of individual cytokines (e.g., reducing IL-6, increasing IL-10); however, it is not known whether exercise during chemotherapy affects relationships between cytokines (i.e., whether cytokine concentrations change collectively vs. independently). This study assessed how 6 weeks of exercise during chemotherapy affected relationships between changes in concentrations of several cytokines.Methods: This is a secondary analysis of a randomized trial studying 6 weeks of moderate-intensity walking and resistance exercise during chemotherapy compared with chemotherapy alone. At pre- and post-intervention, patients provided blood to assess serum concentrations of cytokines IL-1β, IL-6, IL-8, IL-10, and IFN-γ, and receptor sTNFR1. We investigated relationships between cytokines using the correlations between changes in cytokine concentrations from pre- to post-intervention.Results: We obtained complete data from 293 patients (149 randomized to exercise). Exercise strengthened the correlation between concentration changes of IL-10 and IL-6 (r = 0.44 in exercisers vs. 0.11 in controls; p = 0.001). We observed the same pattern for IL-10:IL-1β and IL-10:sTNFR1. Exercise also induced an anti-inflammatory cytokine profile, per reductions in pro-inflammatory IFN-γ (p = 0.044) and perhaps IL-1β (p = 0.099, trend-level significance).Conclusions: Our hypothesis-generating work suggests that regular exercise during 6 weeks of chemotherapy may cause certain cytokine concentrations to change collectively (not independently). This work enhances our understanding of relationships between cytokines and complements traditional analyses of cytokines in isolation. Future work should test for replication and relationships to patient outcomes.Trial Registration: Clinical Trials.gov, # NCT00924651, http://www.clinicaltrials.gov . [ABSTRACT FROM AUTHOR]

Introduction: Biliary atresia is a rare neonatal disease and the most common indication for pediatric liver transplantation. Kasai portoenterostomy is the initial treatment, aiming to prevent liver transplantation. Beyond age at Kasai, few prognostic factors are known. Multiple countries have established screening methods to reduce the age at Kasai and recent analysis shows significant better outcomes for screening cohorts. In 2016, we established a decentralized stool color card screening in Lower Saxony and we present our first 2 years of experiences.Methods: In cooperation with a major German health insurance company and the Medical Association of Lower Saxony, we established the screening project, printed 120,000 color cards, and distributed them to all maternity hospitals. Program advertises were printed in newspapers and medical journals. After the first year, the project was evaluated. Thirty maternity hospitals and local practitioners were contacted via telephone, Internet, intranet, and pediatric journals.Results: One out of seventy-six maternity hospitals (1.3%) refused to participate in the screening. 30 hospitals (40%) were contacted and 93.5% of the interviewed staff reported that stool color cards were handed out regularly and discussed with the parents. Only 20% of local practitioners assessed neonatal cholestasis to be a relevant problem during daily practice, and 55% regarded a stool color card screening to be useful.Conclusions: In the second year, we extended the screening project to outpatient maternity clinics. Based on the responses of local practitioners, we regard the voluntary screening as insufficient and we have contacted the Federal Joint Committee for the initiation of a nationwide obligatory stool color card screening. [ABSTRACT FROM AUTHOR]

The cyclic ferroelastic hysteretic behavior of pure LaCoO 3 perovskite ceramic has been studied at different temperatures in four point bending. The stress-strain deformation behavior of LaCoO 3 was analyzed both in the term of the maximum stress in the cycle and in terms of the temperature used when the cyclic testing was performed. The characteristics of the stress-strain hysteresis loops, such as hysteresis loop area and irreversible strain, as well as effective Young's modulus, were analyzed, and it was established that both the loading and the temperature history have a significant influence on the mechanical behavior of LaCoO 3. Young's modulus values are reported to be much higher in the 700–900 °C temperature range as compared to the measurements performed in the RT-400 °C temperature range. [ABSTRACT FROM AUTHOR]

R-curve and controlled stable crack growth behaviour of ZrB2–17vol.-%SiC and ZrB2–45vol.-%SiC ceramic composites was studied on V-notched samples using four-point bending at room temperature. The rising K1R behaviour was determined as a function of the crack extension Δa with a crack bridging mechanism being dominant in such behaviour. Significant differences in crack growth rates were found within the same composition of ceramics simply as the crack length varied during crack growth processes. These differences are indicative of the significant influence of microstructural parameters of the ceramics on crack propagation. The peculiarities of stress intensity factor K1 and the crack growth-specific behaviour in ZrB2–SiC particulate ceramic composites are discussed. [ABSTRACT FROM AUTHOR]

BACKGROUND/OBJECTIVE: Exercise interventions improve anxiety and mood disturbances in patients with cancer. However, studies are limited in older adults with cancer. We assessed the effects of exercise on anxiety, mood, and social and emotional well‐being in older patients with cancer during their first 6 weeks of chemotherapy. DESIGN: Exploratory secondary analysis of a randomized controlled trial (RCT). SETTING: Community oncology practices. PARTICIPANTS: Older patients (aged 60 years or older) undergoing chemotherapy (N = 252). INTERVENTION: Patients were randomized to Exercise for Cancer Patients (EXCAP) or usual care (control) for the first 6 weeks of chemotherapy. EXCAP is a home‐based, low‐ to moderate‐intensity progressive walking and resistance training program. MEASUREMENTS: Analysis of covariance, with study arm as the factor, baseline value as the covariate, and study arm × baseline interaction, was used to evaluate arm effects on postintervention anxiety (State Trait Anxiety Inventory [STAI]), mood (Profile of Mood States [POMS]), and social and emotional well‐being (Functional Assessment of Cancer Therapy–General subscales) after 6 weeks. RESULTS: Median age was 67 years; 77% had breast cancer. Statistically significant group differences were observed in the STAI score (P = .001), POMS score (P = .022), social well‐being (P = .002), and emotional well‐being (P = .048). For each outcome, EXCAP patients with worse baseline scores had larger improvements at 6 weeks; these improvements were clinically significant for STAI score and social well‐being. CONCLUSIONS: Among older cancer patients receiving chemotherapy, a 6‐week structured exercise program improved anxiety and mood, especially among those participants with worse baseline symptoms. Additional RCTs are needed to confirm these findings and evaluate the appropriate exercise prescription for managing anxiety, mood, and well‐being in this patient population. J Am Geriatr Soc 67:1005–1011, 2019. [ABSTRACT FROM AUTHOR]

Room temperature static and cyclic fatigue of ZrB 2 -32 vol% SiC and ZrB 2 -45 vol% SiC particulate ceramic composites has been studied. It was established that the presence of grain bridging plays an important role in the lifetime and time dependent mechanical performance of ZrB 2 -SiC composites. It was also established that the cohesive strength of grain boundaries of the composites was a determining factor if grain bridging would occur during crack growth, as the grain boundaries strength would determine the pathway of the moving crack. Grain bridging was limited in ZrB 2 -32 vol% SiC leading to the absence of a cyclic fatigue effect, while grain bridging indeed occurred in ZrB 2 -45 vol%SiC contributing to a cyclic fatigue effect which limits the lifetime of the composite. Such differences were responsible for the occurrence of R-curve behavior in ZrB 2 -SiC ceramic composites. [ABSTRACT FROM AUTHOR]

A new model is presented that provides an improved understanding of the time dependent fatigue behavior of two phase brittle particulate ceramic composites under static and cyclic loading conditions. The proposed model takes into consideration cyclic fatigue effects, which are responsible for the accelerated fatigue crack propagation in the cyclic loading as compared to the static loading. It also takes into account the effect of both thermal residual stresses and bridging stresses acting in the composite during time dependent crack propagation. Experimental results for the fatigue behavior of ZrB 2 –45 vol%SiC ceramic composite were used as a case study to valid the proposed model. The model gives insight both into the time dependent mechanical behavior of ceramic composites and, at the same time, allows determination of important structural parameter, such as, size of the bridging zone in the material under cycling loading. [ABSTRACT FROM AUTHOR]

Aluminum alloys are light-weight and one of the most interesting material solutions to optimize the strength/weight ratio to reduce car weight; however they are also relatively soft and therefore cannot be used for intensive wear applications. We developed an aluminum alloy part combined with hard and wear-resistant Al 2 O 3 -based ceramic plates on the surface for demanding mechanical parts for automotive industry such as disc brakes. Tribological tests of various engineering ceramic materials were performed in order to find a ceramic material with a combination of coefficient, wear resistance and thermal energy dissipation for the car brakes. Al 2 O 3 -based ceramic showed promising properties, as well as being cost effective. Two different approaches to braze ceramic on aluminum were investigated. A two-step brazing process using Cu-Sn-Ti-Zr filler alloy and a single step ultrasonic active soldering with Sn-Ag-Ti filler alloy. Larger areas of aluminum could be covered with a segmented brake design in which many ceramic plates were joined surface. Comparable tribological properties to those of the bulk ceramic material were achieved. [ABSTRACT FROM AUTHOR]

Aqueous silicon nitride based composite suspensions with the addition of 3.1 wt% of carbon nano-fibers (CNFs) were dried using two different drying techniques: spray drying and freeze drying. The paper deals with optimisation of parameters of the spray drying processwith the aim of maximising the yield and improve the quality of the granulate. Freeze drying was selected as a reference drying method, because no powder separation can occur in the course of the process. Prepared suspensions were spray dried at 4 different temperatures: 80, 110, 140 and 180 °C. After each run, two types of granules were obtained: from the separation flask and from the product vessel. Thermo-gravimetric analysis together with SEM examination show that spray drying results in separation of CNFs agglomerates. The granules from separation flask are always enriched by CNFs agglomerates whilst the granules from product vessel have reduced content of CNFs agglomerates. Sintering of spray-dried granules from the product vessel resulted in the composite with uniform microstructure, low amount of CNFs agglomerates and high relative density. [ABSTRACT FROM AUTHOR]

Elastic properties (Young׳s modulus, shear modulus, and Poisson׳s ratio) of ZrB 2 , SiC ceramics and ZrB 2 –SiC ultra high temperature ceramic composites were measured by the Impulse Excitation technique in the RT–1173 K temperature range. Two compositions of ZrB 2 with 17 vol% and 32 vol% of SiC strengthening phase were hot pressed to almost full density, followed by machining before the measurements took place. The temperature dependences of elastic properties have shown the expected softening behavior, where only small 4% and 5% linear reduction in Young׳s and shear moduli were detected, respectively, for ZrB 2 –17 vol% SiC and ZrB 2 –32 vol% SiC ceramic composites. The reported decrease in elastic moduli brings the respective linear increase of Poisson׳s ratio up to ~9% in the temperature of interest. Such high temperature behavior corresponds well to the upper and lower bounds of elastic moduli of two ZrB 2 –SiC ceramic composites calculated by Voigt and Reuss estimations using properties of pure ZrB 2 and pure SiC ceramics, as published in the literature. [ABSTRACT FROM AUTHOR]

Abstract: The resistance to breakage of sapphire samples of different crystallographic orientations and produced by the Kyropoulos and Verneuil processes was investigated. The fracture strength was determined by using four-point bending tests, whereas the single-edge V-notch beam method was used to measure the fracture toughness. For both mechanical properties, it was found that (i) Verneuil sapphire has values up to two times higher than Kyropoulos sapphire and (ii) the data scatter is also generally higher for Verneuil sapphire. The main factor responsible for this behavior is believed to be the presence of mosaicity in Verneuil and its absence in Kyropoulos sapphire. By using the Read–Shockley model to estimate the energy of low-angle grain boundaries, together with the Griffith energy criterion for intergranular crack propagation, it is demonstrated that intergranular fracture along the mosaic block boundaries is energetically more favorable than transgranular fracture for crack-to-boundary orientations smaller than a critical deflection angle. Nevertheless, both the location of the crack in respect to the boundary, as well as the 3-D nature of these features, must be taken into consideration for a complete description of the intergranular deflection toughening mechanism. [Copyright &y& Elsevier]

Background: The neonatal surgical patient is threatened by exuberant inflammatory reactions. Neonatal macrophages are key players in this process. We investigated the ability of neonatal macrophages to initiate a local inflammatory reaction upon exposure to different bacterial or viral ligands to toll-like receptors (TLRs). Methods: Peritoneal wash outs from neonatal (<24 h) and adult (42 days) C57BL/6J mice were gained by peritoneal lavages. In a first set of experiments, macrophages were purified and stimulated for 6 h by four different TLR ligands. mRNA was extracted for transcriptome analysis. In a second set of experiments, lipopolysaccharide was applied into peritoneal cavities. After 6 h of incubation, the cellular composition of the inflamed cavities was evaluated by cytological staining as well as chipcytometry. Results: Neonatal murine peritoneal macrophages differed significantly in the expression of pro- and anti-chemotactic genes. Functional assignment of these genes revealed enhanced chemotactic potential of neonatal macrophages and was confirmed by a higher influx of pro-inflammatory cells into neonatal peritoneal cavities. Conclusion: Neonatal peritoneal macrophages demonstrated an enhanced chemotactic potential upon stimulation with four TLR ligands. This was associated with an increased influx of inflammatory cells to the peritoneal cavity. This might contribute to the strong inflammatory responses of neonates and preterms. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, the fracture toughness and the corrosion behaviour of particle reinforced alumina–steel composites were investigated. Composites, only differing in their type of matrix steel, were produced by Ti-activated pressureless infiltration. The aim was to clarify the influence of the matrix phase on the electrochemical properties as well as on the fracture toughness of the composites. Results show that the corrosion resistance of the composite mainly depends on the steel matrix. The processing history of the matrix steel is determining. Melt-processing decreases the corrosion resistance. All composites exhibit failure-tolerant behaviour. Though, local differences in the matrix plasticity on the micro-scale have been observed. Failure occurs primarily through Al2O3-particles. The increase in resistance against crack propagation, from about 8 to more than 30MPam1/2 after 1mm crack extension, is attributed to the metallic matrix phase remaining intact behind the propagating crack front. [Copyright &y& Elsevier]

Abstract: Room temperature time dependent properties of ZrB2–30wt%SiC ceramic composite have been studied. Both static slow crack growth and cyclic fatigue deformation have been investigated. While static slow crack growth has been evaluated only in air, three different environments, water, air, and dry air, have been used to study the cyclic fatigue. It was established that under cyclic fatigue the environment plays an important role and humidity significantly facilitate crack growth in ZrB2–30wt%SiC. The fractography of selected ZrB2–30wt%SiC samples was performed and it was established that both defects introduced during machining as well as larger defects introduced during the processing served as fracture origins of ceramic composites. [Copyright &y& Elsevier]

Abstract The mechanical properties of ZrB2-30 wt-%SiC ultra high temperature ceramic composites have been studied. The composite was processed by hot pressing at 2100°C, 30 MPa and 45 min dwell time to achieve a good densification. Young's modulus, single edge V notch beam fracture toughness, hardness, stress-strain deformation, four-point bending strength and Weibull parameters were measured. Fractography and microstructure analyses of ZrB2-30 wt-%SiC ceramic composite were also performed. [ABSTRACT FROM AUTHOR]

Abstract: Application of Al2O3|P-steel MMCs as wear resistant components is often restricted due to their lack of toughness under impact stress. Therefore, the influence of the microstructural features on the impact toughness was studied for Al2O3|P-steel MMCs fabricated by Ti-activated melt infiltration. Composites differing in ceramic reinforcement fraction and size as well as in the steel matrix were evaluated by means of Charpy impact testing, tensile testing and microscopic analysis. Although, MMCs exhibit brittle fracture behaviour, local plastic behaviour was identified. Based on the results the effect of Al2O3-reinforement phase is not the primary factor to improve impact behaviour of MMCs. Ti-enrichment was identified as having the most crucial effect on the composite impact toughness. Enrichment of Ti-activator within the matrix steel as well as brittle Ti-rich precipitations combined with hardening of the steel due to melt processing decrease the MMC toughness drastically. Hence, a matrix steel insusceptible to precipitation hardening and Ti-enrichment or a reduction of Ti-activator amount are therefore key requirements to produce high-volume fraction MMCs with adequate impact toughness. [Copyright &y& Elsevier]

Abstract: Si3N4/SiC composites used for industrial wood cutting were processed by a near net shape route involving gas pressure sintering with sintering additives such as Al2O3, La2O3, Y2O3 and MgO. The cutting edge integrity of these knives was tested in a cutting trial and compared to knives made by a hot pressing route. It was found that the intergranular phase has a crucial influence on the cutting edge integrity. The boundary phase was analysed by EFTEM and EDX mapping on TEM samples: in gas pressure sintered composites the crystallisation of the apatite Y5Si3O12N phase was identified. In the hot pressed composite the boundary phase consisted only of silicates. These composites showed better edge stability than cutting tools with a Y–N-apatite phase. The formation of the type of intergranular phase was found to be determined by the amount of MgO sintering aid and the temperature of the post sintering heat treatment. [Copyright &y& Elsevier]

Abstract: It is known that theoretical considerations of fracture under loading by a spherical indenter are based on the concept of pre-existing cracks. However, nucleation and growth of the critical crack could occur during indentation, as happens during microcracking. The goal of the presented research is to develop a new concept of fracture under spherical indentation in a brittle elastic material taking into account the possibility of critical crack nucleation and growth during loading. La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) perovskite has been chosen as a polycrystalline elastic low fracture toughness ceramic to perform indentation using a tungsten carbide spherical indenter. Experimental measurements of ring crack radii for well-polished LSGM cannot be explained within the framework of the pre-existing crack hypothesis. The local risk calculated using the concept of pre-existing cracks gives a most probable range of ring crack radii that does not match the radii measured experimentally. However, the local risk calculated using the assumption of critical crack nucleation and formation during spherical indentation results in a most probable range of ring crack radii which exhibits good agreement with the experimental data. [Copyright &y& Elsevier]

Abstract: Si3N4/SiC cutting tools were fabricated by industrial near net shape fabrication processes. The samples were consolidated by gas-pressure sintering and pressure less sintering using three different additive systems. The mechanical and microstructural properties were compared to composites made by hot pressing. The composites fabricated by gas-pressure sintering showed 99% density, the Vickers hardness was 17.2GPa and the fracture toughness reached 4.5MPa√m. Machining trials on wood showed that a post-sintering treatment by hot isostatic pressing increases the integrity of the cutting tip due to a devitrification of the intergranular phase. [Copyright &y& Elsevier]

Introduction: Recently, we showed that various procedures for rigid Natural Orifice Transluminal Endoscopic Surgery (NOTES) can be successfully performed in piglets. However, the safety and effectiveness of endoscopic closure of the urinary bladder remains to be determined before introducing transurethral NOTES in children. Our study was designed to investigate the safety and impermeability of the urinary bladder after endoscopic closure in transurethrally assisted nephrouretectomy in piglets.Material and Methods: Five female piglets (mean weight 14.5 kg; range: 14-15) underwent right-sided transurethral nephroureterectomy using a hybrid technique with one 15 mm trocar placed umbilically and one 3 mm trocar placed transvesically. Hilar dissection was performed with a 5 mm Endoligasure vessel sealing device. After umbilical retrieval of the resected kidney, the urinary bladder was closed by an Endoloop via an umbilical "two in one system" with the assistance of a 2 mm transurethrally placed endoscopic clamp. Endpoints of the study were total operation time, duration of cystoscopy and transurethral trocar positioning, duration of nephrectomy, duration of bladder closure and determination of bladder impermeability. Intraoperatively, bladder filling was performed with normal saline (ml), while bursting pressure (mmHg) was measured by filling the harvested bladder with air.Results: All nephroureterectomies were successfully performed with negligible blood loss. Mean total operation time was 46 min (range: 35-69). Cystoscopy and transurethral trocar positioning took 14 min (range: 9-23), and nephrectomy took 28 min (range: 18-48). Mean duration of bladder closure was 4 min (range: 2-6). Mean volume of intraoperative bladder filling was 94 ml (range: 80-100), indicating adequate capacity after closure with Endoloops. Post-mortem bladder impermeability was confirmed by a mean air filling bursting pressure of 88 mmHg (range: 70-140) indicating sufficient bladder closure.Conclusion: A safe urinary bladder closure is mandatory for transurethral rigid NOTES procedures and can be adequately achieved with Endoloops. [ABSTRACT FROM AUTHOR]

Abstract: The fabrication method and the mechanical and electrical properties of different MoSi2–Si3N4 composite materials were investigated. Commercially available individual compounds, one-stage combustion synthesized MoSi2–Si3N4 and submicron MoSi2 powders were used as starting materials, followed by hot pressing. It was found that the sintering atmosphere used, nitrogen or argon, had a significant effect on the phase composition, mechanical and electrical properties of the final materials. It was shown that in some cases partial nitridation of MoSi2 occurred with the formation of MoSi2–Mo5Si3–Si3N4 ternary composites. The electrical conductivity of the composites depends also on the microstructure of materials. It was shown that the composites fabricated using combustion synthesized MoSi2 powders (500nm) are characterized by higher flexural strength at room temperature compared to those from commercial powders. On the other hand, the composites fabricated from the commercial powders had higher strength and fracture toughness at elevated temperatures (up to 1200°C). For all composites, the strength decreased significantly at temperatures over 1000°C due to the brittle–ductile transition of the MoSi2 phase. [Copyright &y& Elsevier]

Three-dimensional interconnected alumina/steel metal matrix composites (MMCs) were produced by pressureless Ti-activated melt infiltration method using three types of Al2O3 powder with different sizes and shapes. By partial sintering during infiltration an interpenetrating ceramic network was realised. The effect of the ceramic particle size and shape on the resulting ceramic network, volume % fraction and the MMC properties is presented. The MMCs were characterised for mechanical properties at room temperature and elevated temperature. An increase in flexural strength and Young’s modulus with decreasing particle size has been observed. In addition, the effect of the volume of ceramic content and the surface finish of the MMCs on the wear behaviour is shown. [ABSTRACT FROM AUTHOR]

Abstract: The possibilities of the synthesis of submicron MoSi2 and MoSi2–Si3N4 composite powders were investigated using inorganic salt-assisted combustion synthesis method. Combustion laws in the MoO3–3Mg–2Si–NaCl and Mo–5Si–NaCl–Si3N4–N2 systems were studied. The main factors influencing the combustion parameters, phase composition and microstructure of products for both these systems were determined experimentally. Optimum synthesis conditions of submicron MoSi2 and MoSi2–Si3N4 composite powders containing 30–40wt.% of molybdenum disilicide were determined. Compacting conditions for 30wt.% MoSi2–70wt.% Si3N4 composite using the hot pressing technique were found. Compact samples 20mm in diameter were obtained. Microstructure, phase and chemical compositions of the dense samples were studied. [Copyright &y& Elsevier]

Abstract: Zirconia-based metal matrix composites (MMCs) were produced by the pressureless activated melt infiltration method. Porous titanium activated preforms based on monoclinic ZrO2 and partially stabilised ZrO2 powders (Ca-PSZ, Mg-PSZ) were infiltrated by steel melt under vacuum. The generated microstructures were studied by SEM and EDX and the Young''s modulus and the bending strength were determined. In addition, first trials have been carried out in order to illustrate the impact of the martensitic transformation of zirconia and the associated induced stresses on the mechanical properties of the zirconia-based MMCs. Finally, the wear behaviour of the composites was investigated. [Copyright &y& Elsevier]

Abstract: Metal matrix composites (MMC) combine the properties of metals and ceramics to yield failure tolerant materials. Using ceramic foams, these composites become three-dimensional structures of intimately connected metal and ceramic which should possess, e.g. high wear resistance. Once the problem of inherently poor wetting of ceramic by metal melts is eliminated, MMCs can be produced by spontaneous infiltration of metal into a ceramic structure, i.e. by pressureless infiltration. At the crucial infiltration step, an activator such as elemental titanium must be spread over the ceramic surface. In contact with the melt, the elemental Ti significantly improves the wetting, so that the metal can spontaneously infiltrate the ceramic structure. In this study, a halide salt route and a wet TiH2 route were investigated as activation methods with which to generate Ti activation in alumina foams. Both methods enabled activation of alumina foams within the range of 20–90pores per inch (ppi) pore size and promoted spontaneous metal infiltration of Inconel 625 and X38CrMoV5-1 into the activated structures. [Copyright &y& Elsevier]

Abstract: The possibilities for combustion synthesis of TiN–Si3N4 composite powders were investigated using different titanium silicides (TiSi, Ti5Si3, TiSi2) as initial raw materials. Thermodynamic analysis and relevant experiments have shown that at relatively low nitrogen pressure (up to 5MPa) Ti5Si3 is the most suitable compound for this purpose. Optimum experimental conditions for synthesizing two-phase silicon-free TiN–Si3N4 (containing 30–35wt.% TiN) composite powders with characteristic sizes of approximately 5–10μm were determined. Compact discs of 50mm diameter were fabricated using hot pressing technique. Microstructural features of the composite powder and hot pressed samples were investigated, i.e. biaxial flexure strength. [Copyright &y& Elsevier]

Abstract: Industrial wood-cutting inserts were produced from both Si3N4- and Si3N4-based ceramic matrix composites (CMC), subjected to industrial wood-cutting conditions and compared to tungsten carbide (WC). Relevant material properties for this particular application were collected and compared to the results obtained from the cutting tests. The results show that Si3N4/30wt.% SiC gives the best balance between fracture toughness and wear. An yttria/lanthana sintering aid system allows the production of a very fine-grained microstructure without decreasing the fracture toughness. Post-hipping and crack-healing operations have been shown to be of paramount importance for the survivability of the cutting edges. An extrapolation from the lifetime prediction test gives a potential lifetime for the CMC material three times that obtained from the WC. [Copyright &y& Elsevier]

Background: This study aimed to determine the impact of prior surgery on the feasibility of laparoscopic surgery for children.Methods: A prospective study analyzed 471 consecutive children who underwent laparoscopic surgery over a 4-year period. Laparoscopic procedures were classified "easy," "difficult," or "demanding." The end points of the study were conversion rate, intraoperative events, and duration of operation.Results: A total of 89 patients (19%) had undergone previous abdominal surgery. The conversion rate was 18% for the patients with prior surgery versus 9% for those without a prior operation (16/89 vs 35/382; p < 0.05). This difference reflects a significantly higher conversion rate for "easy" procedures among patients with than among those without prior surgery, but not for "difficult" and "demanding" procedures. The type of prior surgery had no significant impact on the mean duration of the operation. Of 71 procedures, 12 (17%) after prior conventional surgery were converted, as compared with 4 (22%) of 18 after prior laparoscopy (p > 0.05). Intraoperative events, mainly attributable to adhesions and lack of overview, occurred in 8% of patients with prior procedures, as compared with 2% without former surgery (7/89 vs 9/382; p < 0.05). Relevant complications were not significantly more frequent after prior surgery. The incidence of conversions decreased with increased time between current and previous surgery. It was 64% for surgeries less than 1 year later, 25% for surgeries 1 to 5 years later, and 5% for surgeries more than 5 years later (7/11 vs 6/24 vs 3/54; p < 0.001).Conclusions: Prior surgery has a limited impact on the feasibility of laparoscopic surgery for children. The conversion rate and the incidence of intraoperative events, mainly because of adhesions and lack of overviewing, is increased, but not the incidence of relevant complications. The feasibility improves considerably with increased time between surgery and prior surgery. The authors consider laparoscopy to be the first-choice technique after prior surgery. [ABSTRACT FROM AUTHOR]