Effect of Running Parameters on Flow Boiling Instabilities in Microchannels.

Flow boiling instability (FBI) in microchannels is undesirable because they can induce the mechanical vibrations and disturb the heat transfer characteristics. In this study, the synchronous optical visualization experimental system was set up. The pure acetone liquid was used as the working fluid, and the parallel triangle silicon microchannel heat sink was designed as the experimental section. With the heat flux ranging from 0-450 kW/m2 the microchannel demand average pressure drop-heater length (Δp(ave)L) curve for constant low mass flux, and the demand pressure drop-mass flux (Δp(ave)G) curve for constant length on main heater surface were obtained and studied. The effect of heat flux (q = 188.28, 256.00, and 299.87 kW/m2), length of main heater surface (L = 4.5, 6.25, and 8.00 mm), and mass flux (G = 188.97, 283.45, and 377.94 kg/m2s) on pressure drops (Ap) and temperatures at the central point of the main heater surface (Twc) were experimentally studied. The results showed that, heat flux, length of the main heater surface, and mass flux were identified as the important parameters to the boiling instability process. The boiling incipience (TBI) and critical heat flux (CHF) were early induced for the lower mass flux or the main heater surface with longer length. With heat flux increasing, the pressure drops were linearly and slightly decreased in the single liquid region but increased sharply in the two phase flow region, in which the flow boiling instabilities with apparent amplitude and long period were more easily triggered at high heat flux. Moreover, the system pressure was increased with the increase of the heat flux.

[Trunk sap flow dynamic changes in response to the slopes of plantation of Toona ciliata var. pubescens].

The sap flow and environmental factors, including temperature, water content and water potential of soil, were continuously measured by using an auto-data collection system at the upper and lower slopes of Toona ciliata var. pubescens plantation in July to October, 2012 to investigate the relationships between the sap flow and environmental factors. The results showed that, the trunk sap flow velocity of the two positions both presented a typical single-peak curve, with high values in the daytime and low values in the nighttime. The average sap flow of the lower slope was significantly higher than that of the upper slope. Soil temperature of the upper slope was significantly higher than that of the lower slope, and soil water content and water potential were vice versa. Soil water content and water potential were the leading environmental factors affecting the trunk sap flow velocity at the lower slope, while soil temperature and water potential were the main environmental factors at the upper slope.

[Long-term effects of thinning on carbon storage in Cunninghamia lanceolata plantations].

The stand environment and tree growth could be changed as well as carbon storage be affected by thinning. Thus it is important to conduct the research on changes of carbon stock in plantations after thinning for assessing the dynamics of forest ecosystem carbon pool. The carbon storage and its distribution of various components in 22-year-old Cunninghamia lanceolata plantations were studied with control and different treatments such as moderate and heavy thinning. Moderate (thinning intensity was 35%) and heavy (thinning intensity was 50%) thinning treatments were conducted twice at the age of 7 and 14 years, respectively. The stand of control was thinned 15% in the 14th year. The results showed that the proportion of stem carbon storage increased with the increasing thinning intensity, while the proportion of carbon storage in branches, leaves and roots slightly decreased, which suggested that thinning was beneficial for carbon stocking in stem. However, the carbon storage in arbor layer decreased with the thinning intensity in C. lanceolata plantation under moderate and heavy thinning treatments, accounted for 89.0% and 83.1% of the control, respectively. The arbor carbon storage decreased in followed two years after the first thinning. The carbon storage in arbor layer had a fast recovery rate within eight years after the second thinning, and the increment of carbon storage in arbor layer had no difference with the control for the heavy thinning treatment. The carbon storage in understory vegetation, litter and soil layers also had no significant difference under the different thinning treatments. Generally total ecosystem carbon storage under the control, moderate and heavy thinning treatments reached 169.34, 156.65 and 154.37 t x hm(-2), respectively. There was no significant difference among the three treatments. Therefore, it could be concluded that the carbon storage in C. lanceolata plantation did not reduce after thinning in more than 15 years.

[Surgical treatment of esophageal carcinoma with cervical esophagogastrostomy by left thoracic esophagectomy].

OBJECTIVE: To evaluate the effects of surgical treatment with cervical esophagogastrostomy by left thoracic esophagectomy on esophageal carcinoma. METHODS: The clinical data of 3169 patients with esophageal carcinoma, 2115 males and 1054 females, aged 60.9 (30-82), that underwent cervical esophagogastrostomy by left thoracic esophagectomy from Jan. 1990 to Dec. 2000 were analyzed retrospectively. RESULTS: The incidence of complication was 8.6% (273). The operative mortality was 0.6% (19). The 1, 3, and 5 year survival rates were 81.5%, 51.6%, and 32.1% respectively. Manometric examination of the digestive tract showed that the post-operative resting pressure of residual esophagus above the anastomotic stoma was (16+/-11 mm Hg), significantly higher than that of the cervical esophagus of the normal controls [(4+/-3) mm Hg), P<0.01]. CONCLUSION: Reducing incidence of gastroesophageal reflux and improving the quality of life of patients, cervical anastomosis should be recommended as the first choice procedure in treatment of upper and middle segment esophageal carcinoma.

[Blunt esophageal denudation without thoracotomy in the treatment of cervical esophageal carcinoma with laryngeal function preservation].

OBJECTIVE: To study the feasibility and effect of Blunt esophageal denudation without thoracotomy in the treatment of cervical esophageal carcinoma with laryngeal function preservation. METHODS: The data of 28 patients with cervical esophageal carcinoma, collected from Aug. 1997 to Nov. 2005, were investigated retrospectively. RESULTS: All the 28 patients were diagnosed as cervical esophageal squamous cell carcinoma. Among them, 12 patients underwent surgery (surgery group), while the other 16 patients underwent surgery plus radiation therapy preoperatively or postoperatively (multimodality therapy group). No uncontrolled intraoperative and postoperative hemorrhage and tracheal tear occurred. The incidence of complications was 21.4% (6/28), including cervical anastomotic leakage in 2 patients and recurrent laryngeal nerve injury in 4 patients. The overall 5-year survival rate was 50.3%. The 5-year survival rate was 25.7% in surgery group and 66.1% in multimodality therapy group, and the difference between two groups was statistically significant (chi(2)=4.07; P=0.0438). CONCLUSIONS: Blunt esophageal denudation without thoracotomy in the treatment of cervical esophageal carcinoma with larynx function preservation is possible. Combined with radiotherapy preoperatively or postoperatively, the survival time in patients with cervical esophageal carcinoma is able to be prolonged.

[Characteristics of lymph node metastasis in thoracic esophageal carcinoma].

OBJECTIVE: To investigate the frequency, distribution, and feature of lymph node metastasis in thoracic esophageal carcinoma, and to provide evidence for lymph node dissection and the multidisciplinary therapy for patients with esophageal carcinoma postoperatively. METHODS: The clinical data of 623 patients with thoracic esophageal carcinoma who had undergone esophagectomy plus lymph node dissection were studied to analyze the characteristics of lymph node metastasis. RESULTS: Totally 3689 of lymph node groups (with 8603 nodes) were dissected. The lymph node metastasis rate was 47.2% and lymph node metastasis ratio was 10.3%. No lymph node metastasis was found in the patients of Tis stage, while lymph node metastasis was found in the patients of other stages. There were significantly differences in lymph node metastasis rate and ratio among the patients of different T stages (chi2 = 38.407, P = 0.00, and chi2 = 118.438, P = 0.000). The higher the T stage, the higher the lymph node metastasis rate and ratio (r = 1, P = 0.000, and r = 1, P = 0.000). Different pathological types of esophageal carcinoma had different lymph node metastasis ratio (chi2 = 84.577, P = 0.000), however, there was no significant difference in lymph node metastasis rate among different pathological types (chi2 = 6.284, P = 0.179). The patients with squamous carcinoma had the lowest lymph node metastasis ratio and lymph node metastasis rate. The lymph node metastasis was mainly regional and extended vertically in both directions. Leaping over metastasis was another feature. All segments of thoracic esophageal carcinoma, especially lower thoracic esophageal carcinoma, could metastasize to the celiac lymph nodes. CONCLUSION: Lymph node dissection should be carried out properly in treatment of esophageal carcinoma and regional celiac lymph nodes should be explored and dissected more cautiously. Because surgical treatment is relatively radical in treatment of esophageal carcinoma, and taking the trend of lymph node metastasis and other indication into account, rational multidisciplinary therapy conducted as soon as possible should be adopted in the treatment of esophageal carcinoma.