Crystalline transformations in nylon-6/single-walled carbon nanotube nanocomposites

Nylon-6/single-walled carbon nanotube (SWNT) nanocomposites with different SWNTs loadings were prepared by melt-blending. An efficient dispersion of SWNTs into the nylon-6 matrix was confirmed by scanning electron microscopy. DSC and time-resolved synchrotron X-ray diffraction were used to provide detailed information on the effect of SWNTs on the crystalline phase transition of nylon-6 in the nanocomposites. The incorporation of SWNTs accelerated the crystallization rate of nylon-6 due to a nucleating effect. The variable-temperature WAXS experiments, in both neat nylon-6 and nylon-6 nanocomposites, showed that the crystallization from the melt occured through the formation of the pseudo-hexagonal crystal form (gamma) and its transformation to the monoclinic form (alpha) on cooling. Additionally, this crystalline transition was reversible as observed upon heating. The alpha-gamma crystalline transformation temperature of nylon-6 was dependent on heating rate and, more importantly, on the SWNT content.

The influence of a compatibilizer on the thermal and dynamic mechanical properties of PEEK/carbon nanotube composites

The effect of polyetherimide (PEI) as a compatibilizing agent on the morphology, thermal, electrical and dynamic mechanical properties of poly(ether ether ketone) (PEEK)/single-walled carbon nanotube (SWCNT) nanocomposites, has been investigated for different CNT loadings. After a pre-processing step based on ball milling and pre-mixing under mechanical treatment in ethanol, the samples were prepared by melt extrusion. A more homogeneous distribution of the CNTs throughout the matrix is found for composites containing PEI, as revealed by scanning electron microscopy. Thermogravimetric analysis demonstrates an increase in the matrix degradation temperatures under dry air and nitrogen atmospheres with the addition of SWCNTs; the level of thermal stability of these nanocomposites is maintained when PEI is incorporated. Both differential scanning calorimetry and synchrotron x-ray scattering studies indicate a slight decrease in the crystallization temperatures of the compatibilized samples, and suggest the existence of reorganization phenomena during the heating, which are favoured in the composites incorporating the compatibilizer, due to their smaller crystal size. Dynamic mechanical studies show an increase in the glass transition temperature of the nanocomposites upon the addition of PEI. Furthermore, the presence of PEI causes an enhancement in the storage modulus, and hence in the rigidity of these systems, attributed to an improved interfacial adhesion between the reinforcement and the matrix. The electrical and thermal conductivities of these composites decrease with the incorporation of PEI. Overall, the compatibilized samples exhibit improved properties and are promising for their use in industrial applications.

A comparison of glycaemic variability in CSII vs. MDI treated type 1 diabetic patients using CGMS

OBJECTIVE

To evaluate and compare glucose variability, hypoglycaemic events and daily glycaemic control in well-controlled (HbA1c <or= 7%), type 1 diabetic patients treated with either continuous subcutaneous insulin infusion (CSII) using lispro or multiple daily insulin injection (MDI) using glargine once daily and lispro with meals.

RESEARCH DESIGN AND METHODS

A total of 16 patients with type 1 diabetes receiving treatment with either CSII (eight patients) or MDI (eight patients), all with HbA1c levels < 7%, wore a continuous glucose monitoring system sensor for 3 days to compare the number, duration, timing and severity of hyperglycaemic and hypoglycaemic episodes.

RESULTS

There were several more episodes of hyperglycaemic [blood glucose (BG) >or= 180 mg/dl] and hypoglycaemic (BG <or= 60 mg/dl) excursions observed in patients treated with CSII than MDI. Glycaemic exposure over 150 mg/dl was similar between the two groups. Maintenance of near-euglycaemia as determined by the average amount of time spent within the glucose range of 80-140 mg/dl was marginally significantly better for the MDI than for the CSII group. Although the CSII group had significantly more hypoglycaemic episodes below 60 mg/dl, the average duration of hypoglycaemia was not significantly different for the two groups. Similar percentages of nocturnal hypoglycaemia were seen. There were no reported major adverse events throughout the duration of the study.

CONCLUSION

Well-controlled type 1 diabetic patients treated with MDI had fewer hyperglycaemic and hypoglycaemic excursions than patients treated with CSII.

Outcome of unresected gastric cancer after laparoscopic diagnosis of peritoneal carcinomatosis

BACKGROUND

Most gastric adenocarcinomas in western countries are locally advanced, and these tumours are often associated with metastatic spread at the time of diagnosis. It is controversial whether palliative surgery can improve symptom control in gastric cancer patients with peritoneal carcinomatosis.

OBJECTIVE

To determine the need of palliative procedures and survival in patients affected by gastric cancer with peritoneal carcinomatosis managed without resection. Methods and materials After standard preoperative staging, 160 patients were diagnosed with resectable gastric adenocarcinoma. Laparoscopy was performed in 107 patients (66.9%), finding peritoneal spread in 22 of them (21%). Seventeen of these patients were not submitted to any additional surgical procedure. Data regarding postoperative morbidity and mortality, need of endoscopic, percutaneous or surgical procedures to palliate symptoms, hospital stay and survival were collected. The same data were collected for the 6 non-resected patients who were diagnosed with carcinomatosis by laparotomy.

RESULTS

In the "laparoscopy alone" group, there were 2 minor complications and no postoperative mortality. Mean postoperative stay was 6 days. Eight patients had to be readmitted to hospital for symptoms derived from tumour progression, and 10 palliative endoscopic procedures were performed. Surgical interventions were not needed in any case. Mean survival was 11.5 months. Patients submitted only to laparotomy presented higher morbidity and mortality rates, with a longer postoperative stay and survival of less than 5 months.

CONCLUSIONS

Laparoscopic staging of gastric cancer can help to avoid unnecessary laparotomies. In patients with peritoneal carcinomatosis diagnosed by laparoscopy, nonsurgical treatment has low morbidity and mortality and permits good symptom relief with no shortening of survival.

Metastatic lymph node ratio as a prognostic factor in gastric cancer

BACKGROUND

There is an association between the number of resected lymph node and the number of metastatic lymph nodes in gastric cancer, suggesting that pN category could be influenced by the extension of the lymphadenectomy. This study evaluates this association and proposes a comprehensive use of the ratio as prognostic factor.

METHOD

Review of 183 consecutive patients with gastric adenocarcinoma. The association between the number of resected lymph nodes and the number of metastatic lymph nodes was analysed and evaluated with other prognostic factors.

RESULTS

The number of lymph node metastases increased with the number of resected lymph nodes. The lymph node ratio was a better prognostic factor than the number of metastatic lymph nodes.

CONCLUSIONS

The metastatic lymph node ratio seems to be a good prognostic factor, but needs further evaluation.

[Laparoscopic resection of hepatic hydatid cyst under general anesthesia with remifentanil infusion]

We report the case of a 52-year-old woman who underwent scheduled laparoscopic resection of a hydatid liver cyst under general anesthesia by infusion of remifentanil and sevoflurane. Surgery was uneventful, although invasive monitoring was required, just as it would have been in major open abdominal surgery, given the risk of bleeding secondary to organ manipulation, the risk of anaphylactic shock related to the etiology of the cyst and the possibility of gas embolism related to laparoscopy. The concept of "minimally invasive" surgery has developed thanks to continued progress in laparoscopy. The considerable advantages of such procedures in comparison with "open" or "conventional" surgery has led to their use with organs such as the liver, which in principle require caution. In such cases, the anesthesiologist must take an approach that is not as simple or minimalist as the term "minimally invasive" might lead us to expect.