Effect of the Charged Pressure on GM Cryocooler Performance.

Presented at the 16th International Cryocooler Conference, held May 17-20, 2008 in Atlanta, Georgia.This paper presents experimental results that show that the refrigeration efficiency of GM refrigerators can be improved by applying a charged pressure. Recently, there has been remarkable progress in superconducting systems, such as magnetic resonance imaging systems, silicon singlecrystal pull-up apparatus, and cryopumps. GM cryocoolers are used to cool these systems because of their high reliability. Thus, to improve the efficiency of superconducting systems, it is important to improve the efficiency of GM cryocoolers. If the compression ratio of a GM cryocooler is reduced, its coefficient of performance (COP) will approach the Carnot COP, since the cryocooler will operate with Simon expansion. Therefore, we investigated the effect of varying the charged pressure of a cryocooler and the cycle frequency on its refrigeration efficiency. We developed a GM cryocooler that can be operated at various charged pressures and we measured its efficiency at various charged pressures and operating frequencies. The optimum charged pressure and operating frequency were determined by comparing the experimental results with numerical simulation results

A randomized multicenter Phase II study of perioperative tiotropium intervention in gastric cancer patients with chronic obstructive pulmonary disease

Sachio Fushida,1,2 Katsunobu Oyama,1,2 Masahide Kaji,2 Yasuo Hirono,2 Jun Kinoshita,1,2 Tomoya Tsukada,1,2 Hideaki Nezuka,2 Tatsuo Nakano,2 Masahiro Noto,2 Koji Nishijima,2 Takashi Fujimura,2 Tetsuo Ohta1,2 1Department of Gastroenterological Surgery, Kanazawa University Hospital, 2Digestive Disease Support Organization (DDSO), Kanazawa, Japan Background: Tiotropium, a long-acting inhaled anticholinergic drug, has been widely used in the treatment of chronic obstructive pulmonary disease (COPD). However, the issue of whether perioperative tiotropium improves postoperative outcomes for gastric cancer patients with COPD remains unclear. Thus, the aim of this study was to determine the efficacy of perioperative tiotropium intervention for gastric cancer patients with COPD.Patients and methods: Eighty-four gastric cancer patients with mild-to-moderate COPD were randomly assigned to receive perioperative pulmonary rehabilitation alone (control group) or pulmonary rehabilitation with 18 µg of tiotropium once daily (tiotropium group). The patients in the tiotropium group received tiotropium for more than 1 week before surgery and for 2 weeks after surgery. Spirometry was performed prior to group assignment and at 2 weeks after surgery. Postoperative complications, forced expiratory volume in 1 second, forced vital capacity, and the ratio of forced expiratory volume in second to forced vital capacity (%) were compared between the two groups.Results: There were no significant differences between the two groups in terms of age, body mass index, smoking, gastrectomy incision, operation time, and bleeding volume (all P>0.05). Postoperative complications and pulmonary functions did not differ significantly between the control and tiotropium groups. A subgroup analysis of gastric cancer patients with moderate COPD showed that perioperative tiotropium intervention significantly decreased the rate of postoperative complications compared with the control group (P=0.046). However, even after gastrectomy, many patients with mild COPD in both the control and tiotropium groups showed improved pulmonary function.Conclusion: Although perioperative tiotropium intervention had no significant effects in gastric cancer patients with mild COPD, it may be beneficial in those with moderate COPD. Therefore, the next prospective study should further evaluate perioperative tiotropium intervention for gastric cancer patients with moderate-to-severe COPD. Keywords: gastric cancer, COPD, tiotropiu