Tooling design and microwave curing technologies for the manufacturing of fiber-reinforced polymer composites in aerospace applications

The increasing demand for high-performance and quality polymer composite materials has led to international research effort on pursuing advanced tooling design and new processing technologies to satisfy the highly specialized requirements of composite components used in the aerospace industry. This paper reports the problems in the fabrication of advanced composite materials identified through literature survey, and an investigation carried out by the authors about the composite manufacturing status in China’s aerospace industry. Current tooling design technologies use tooling materials which cannot match the thermal expansion coefficient of composite parts, and hardly consider the calibration of tooling surface. Current autoclave curing technologies cannot ensure high accuracy of large composite materials because of the wide range of temperature gradients and long curing cycles. It has been identified that microwave curing has the potential to solve those problems. The proposed technologies for the manufacturing of fiber-reinforced polymer composite materials include the design of tooling using anisotropy composite materials with characteristics for compensating part deformation during forming process, and vacuum-pressure microwave curing technology. Those technologies are mainly for ensuring the high accuracy of anisotropic composite parts in aerospace applications with large size (both in length and thickness) and complex shapes. Experiments have been carried out in this on-going research project and the results have been verified with engineering applications in one of the project collaborating companies

Y1 and Y5 Receptors Are Both Required for the Regulation of Food Intake and Energy Homeostasis in Mice

Neuropeptide Y (NPY) acting in the hypothalamus is one of the most powerful orexigenic agents known. Of the five known Y receptors, hypothalamic Y1 and Y5 have been most strongly implicated in mediating hyperphagic effects. However, knockout of individual Y1 or Y5 receptors induces late-onset obesity – and Y5 receptor knockout also induces hyperphagia, possibly due to redundancy in functions of these genes. Here we show that food intake in mice requires the combined actions of both Y1 and Y5 receptors. Germline Y1Y5 ablation in Y1Y5−/− mice results in hypophagia, an effect that is at least partially mediated by the hypothalamus, since mice with adult-onset Y1Y5 receptor dual ablation targeted to the paraventricular nucleus (PVN) of the hypothalamus (Y1Y5Hyp/Hyp) also exhibit reduced spontaneous or fasting-induced food intake when fed a high fat diet. Interestingly, despite hypophagia, mice with germline or hypothalamus-specific Y1Y5 deficiency exhibited increased body weight and/or increased adiposity, possibly due to compensatory responses to gene deletion, such as the decreased energy expenditure observed in male Y1Y5−/− animals relative to wildtype values. While Y1 and Y5 receptors expressed in other hypothalamic areas besides the PVN – such as the dorsomedial nucleus and the ventromedial hypothalamus – cannot be excluded from having a role in the regulation of food intake, these studies demonstrate the pivotal, combined role of both Y1 and Y5 receptors in the mediation of food intake

Laparoscopic correction of perforated peptic ulcer: first choice? A review of literature

Background Perforated peptic ulcer (PPU), despite antiulcer medication and Helicobacter eradication, is still the most common indication for emergency gastric surgery associated with high morbidity and mortality. Outcome might be improved by performing this procedure laparoscopically, but there is no consensus on whether the benefits of laparoscopic closure of perforated peptic ulcer outweigh the disadvantages such as prolonged surgery time and greater expense. Methods An electronic literature search was done by using PubMed and EMBASE databases. Relevant papers written between January 1989 and May 2009 were selected and scored according to Effective Public Health Practice Project guidelines. Results Data were extracted from 56 papers, as summarized in Tables 1-7. The overall conversion rate for laparoscopic correction of perforated peptic ulcer was 12.4%, with main reason for conversion being the diameter of perforation. Patients presenting with PPU were predominantly men (79%), with an average age of 48 years. Onethird had a history of peptic ulcer disease, and one-fifth took nonsteroidal anti-inflammatory drugs (NSAIDs). Only 7% presented with shock at admission. There seems to be no consensus on the perfect setup for surgery and/or operating technique. In the laparoscopic groups, operating time was significant longer and incidence of recurrent leakage at the repair site was higher. Nonetheless there was significant less postoperative pain, lower morbidity, less mortality, and shorter hospital stay. Conclusion There are good arguments that laparoscopic correction of PPU should be first treatment of choice. A Boey score of 3, age over 70 years, and symptoms persisting longer than 24 h are associated with higher morbidity and mortality and should be considered contraindications for laparoscopic intervention

Avaliação das aderências pós-operatórias em ratos submetidos a peritoniostomia com tela de polipropileno associada à nitrofurazona

RACIONAL: Lesões peritoniais, comuns no per e pós-operatório, levam à formação de aderências, cuja incidência aumenta ainda mais com o uso de telas de polipropileno. A nitrofurazona é uma substância que acelera o processo de cicatrização e, devido a isso, cogitou-se a possibilidade de uma ação sobre as aderências peritoniais. OBJETIVO: Avaliar as aderências pós-operatórias em ratos submetidos a peritoniostomia com fixação de tela de polipropileno associada a nitrofurazona. MATERIAL E MÉTODOS: Utilizaram-se 33 ratos Wistar, divididos em 3 grupos de 11 animais, sendo no grupo I realizado laparotomia com exposição da cavidade ao ar ambiente e posterior laparorrafia; no grupo II, ressecção de fragmento da parede abdominal com fixação de tela de polipropileno no espaço e no grupo III, procedimento semelhante ao do grupo II, porém com tela embebida em nitrofurazona. Após 45 dias foram sacrificados e necropsiados. RESULTADOS: Dos animais do grupo I, sete não tiveram aderências (grau 0), dois tiveram aderências de grau 1 e dois de grau 2. No grupo II, 1 foi classificado como grau 3 e 10 como grau 4. No grupo III, um foi de grau 0, oito de grau 3 e um de grau 4 (um animal foi a óbito antes de 45 dias). Todas as aderências encontradas envolveram parede abdominal; 10 animais tiveram aderências envolvendo apenas o omento (grupo I = 4; grupo II = 1 e grupo III = 5); 11 animais tiveram aderências envolvendo o omento, as alças intestinais e outros órgãos abdominais, sendo 10 do grupo II e um do grupo III; três animais tiveram aderências envolvendo apenas alças intestinais, sendo todos do grupo III. Dos 14 animais que tiveram aderências envolvendo as alças intestinais, 10 eram do grupo II (9 com mais de um ponto) e 4 do grupo III (3 com somente um ponto de fixação). CONCLUSÃO: O uso de nitrofurazona associado à tela de polipropileno não reduziu significativamente a incidência de aderências pós-operatórias em ratos, porém diminuiu a intensidade e gravidade dessas aderências.BACKGROUND: Peritoneal injuries, common in per and postoperative, lead to the formation of adhesions. The use of polypropylene mesh increases the postoperative adhesions incidence. Based on the fact of nitrofurazone accelerates the healing process, a possible action on peritoneal adhesions was cogitated. AIM: To evaluate postoperative adhesions in rats submitted to peritoneostomy with polypropylene mesh fixation associated to nitrofurazone. METHODS: Thirty-three Wistar rats were separated into three groups of eleven animals each one. In group I was performed the laparotomy with exposition of the abdominal cavity followed by the laparotomy suture; in group II was performed the resection of a abdominal wall fragment followed by polypropylene mesh fixation on the gap and in group III was performed the same done in group II, but the mesh was previously impregnated with nitrofurazone. After 45 days the animals were sacrificed and necropsied. RESULTS: Seven animals of group I had no adhesions (degree 0), two had degree 1 adhesions and two had degree 2. In group II, one animal was classificated as degree 3 and ten as degree 4. In group III, one had degree 0, eight had degree 3 and one had degree 4 (one animal died before 45 days). All adhesions found involved the abdominal wall; ten animals had adhesions involving only omentum (group I = 4; group II = 1 and group III = 5); eleven animals had adhesions involving omentum, small bowel and other abdominal organs (group II = 10; group III = 1); three animals had adhesions involving only small bowel, all belonged to group III. Fourteen animals had adhesions involving small bowel, of these ten belonged to group II (nine with more than one fixation point) and four belonged to group III (three with just one fixation point). CONCLUSION: The association of nitrofurazone with polypropylene mesh did not reduce significantly the postoperative adhesions incidence in rats, but reduced the intensity and severity of these adhesions

2013 WSES guidelines for management of intra-abdominal infections

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