Theoretical analysis and design of hydro-hammer with a jet actuator: An engineering application to improve the penetration rate of directional well drilling in hard rock formations.

Rapid horizontal directional well drilling in hard or fractured formations requires efficient drilling technology. The penetration rate of conventional hard rock drilling technology in horizontal directional well excavations is relatively low, resulting in multiple overgrinding of drill cuttings in bottom boreholes. Conventional drilling techniques with reamer or diamond drill bit face difficulties due to the long construction periods, low penetration rates, and high engineering costs in the directional well drilling of hard rock. To improve the impact energy and penetration rate of directional well drilling in hard formations, a new drilling system with a percussive and rotary drilling technology has been proposed, and a hydro-hammer with a jet actuator has also been theoretically designed on the basis of the impulse hydro-turbine pressure model. In addition, the performance parameters of the hydro-hammer with a jet actuator have been numerically and experimentally analyzed, and the influence of impact stroke and pumped flow rate on the motion velocity and impact energy of the hydro-hammer has been obtained. Moreover, the designed hydro-hammer with a jet actuator has been applied to hard rock drilling in a trenchless drilling program. The motion velocity of the hydro-hammer ranges from 1.2 m/s to 3.19 m/s with diverse flow rates and impact strokes, and the motion frequency ranges from 10 Hz to 22 Hz. Moreover, the maximum impact energy of the hydro-hammer is 407 J, and the pumped flow rate is 2.3 m3/min. Thus, the average penetration rate of the optimized hydro-hammer improves by over 30% compared to conventional directional drilling in hard rock formations.

Partial splenic embolization using Bletilla striata particles for hypersplenism in cirrhosis: a prospective study.

The article evaluates the long-term follow-up results of PSE using Bletilla striata (BS) particles for hypersplenism in cirrhosis, as compared to PSE using gelfoam particles. Fifty-nine patients with cirrhosis-induced hypersplenism were treated with PSE. The patients were randomly assigned into two groups: gelfoam group, which includes 32 patients using gelfoam particles as the embolic material, and BS group, which includes 27 patients using BS particles. The peripheral blood cell counts and parameters for complications associated with PSE were measured during the follow-up. The mean values of leukocyte and thrombocyte, but not hemoglobin, were significantly increased after PSE (p < 0.01) in both groups. The values of leukocyte and thrombocyte during the long-term follow-up were significantly improved in BS group than that in gelfoam group (both p < 0.01). The frequency of bleeding episodes from esophageal varices in both groups was significantly reduced after PSE (both p < 0.01), but the post-PSE bleeding episodes showed no remarkable differences between the two groups (p = 0.084). Post-embolization syndrome consisted mainly of fever, nausea and vomiting, and abdominal pain in the two groups. The incidence of grade II to III abdominal pain in BS group (82.8%, 27/33) was significantly higher than in gelfoam group (57.9%, 33/57) (p = 0.020). The mean survival time was 61.5 ± 9.1 (median 60, 1-157) months in gelfoam group and 63.4 ± 9.9 (median 52, 0-161) months in BS group, which showed no significant difference (p = 0.930). In conclusion, BS particles could be used as the embolic material in PSE. Compared to gelfoam used in PSE, BS can achieve even better efficacy in alleviating hypersplenism. It provides a long-term effect on the hematological parameters, bleeding from esophageal varices and good palliation, and improved clinical status contributing to symptomatic control.

[Correlation of preoperative plasma levels of big endothelin-1 to prognosis of gastric carcinoma].

BACKGROUND & OBJECTIVE: Endothelin, a potent vasoconstrictor peptide, is involved in mitogenesis modulation, apoptosis, angiogenesis, tumor invasion and metastases. Big endothelin-1 (Big ET-1), the stable precursor of endothelin-1, is regarded as a marker of tumor progression and prognosis. This study was to detect the expression of Big ET-1 in gastric cancer patients, and explore its correlations to progression and prognosis of gastric cancer. METHODS: The plasma levels of Big ET-1 in 118 gastric cancer patients and 20 healthy subjects were detected by enzyme-linked immunosorbent assay (ELISA). The expression of Big ET-1 in primary tumor and para-cancerous gastric tissues of the 118 patients was detected by immunohistochemistry. RESULTS: The plasma level of Big ET-1 was significantly higher in patients with advanced gastric cancer than in patients with early stage gastric cancer and healthy subjects [(5.78+/-1.85) ng/L vs. (3.13+/-1.72) ng/L and (2.46+/-0.59) ng/L, P=0.026, P=0.008]. The plasma level of Big ET-1 was significantly higher in patients with lymph node metastases than in those without [(6.13+/-2.34) ng/L vs. (4.25+/-1.65) ng/L, P=0.006], and significantly higher in stage II, III, IV patients than in stage I patients. During follow-up, patients with high plasma levels of Big ET-1 had higher recurrence rate and lower 2-year survival rate as compared with those with low plasma levels of Big ET-1 (84.6% vs. 60.9%, P=0.034; 38.5% vs. 56.5%,P=0.017). The positive rate of Big ET-1 was significantly higher in stage II,III and IV patients than in stage I patients. CONCLUSION: The plasma level of Big ET-1 may play a vital role in the development, invasion and metastasis of gastric cancer, and may be a predictor of tumor disease severity and prognosis.