Experimental research and application of drilling and blasting with directional damage-reduction shaped charge.

In this research, a directional reduction charging structure was proposed to solve the problems caused by drilling and blasting method such as serious damage to surrounding rocks, working face low contour flatness and serious over-under break of root base c. Drilling and blasting tests, numerical calculations and field applications were designed and performed for the verification of the blasting advantages of charge structure. Test results showed that the peak positive strain along the protection direction of directional protection shaped charge was significantly smaller than that of ordinary charge, where PVC material presented the strongest effect such that the peak positive strain of specimen 1 at measuring point 4 (protection direction) was only 0.27 times that at measuring point 9 (non-protected direction). Numerical simulations indicated shaped jet formation, damage-reduction and charge penetration process and obtained the force law of cement target plate. Experimental results revealed that application of charge in tunnel controlled blasting achieved a clear controlling effect on contour line excavation. Compared with ordinary smooth blasting method, all technical indicators of the developed method were improved such that half hole mark rate was increased by about 33% and the amount of over-under break was decreased by about two times. Research results are of certain significance for the stability of surrounding reserved rocks and formation of roadway in blasting engineering and the developed method was found to be applicable to mining, shaft excavation and other projects.

Research on directional rock blasting based on different slotted pipe materials of the combined charge structure.

For shaped charge blasting projects in mining, civil engineering, and similar fields, it is proposed to modify the charge structure by combining slotted tubes and shaped charge liners to obtain a new type of charge structure. This aims to achieve directional rock breaking through the focused action of the shaped charge. The influence of different slotted pipe materials on the directional rock-breaking effect of concentrated energy using a new charge structure is explored through theoretical analysis combined with model test study, high-speed camera, stress-strain gauge, and other equipment. A comparison is made between slotted pipes made of aluminum, kraft paper, and PVC, with the cutting width of 2 mm. Based on the characteristics of the cracks formed after blasting, the new charge structure made of aluminum slotted pipe produces a penetrating crack that is almost consistent with the pre-cracking direction. Based on the corresponding characteristics of successively released blasting energy, the guiding and convergence effect of the new charge structure made of aluminum slotted pipe on the explosion energy is greater than that of the new charge structure made of the other two types of slotted pipe material. According to the strain data measured after blasting, the peak arrival time of the strain peak in the direction of the slotted pipe on one side of the shaped hood is shorter than that in the other two directions, and the peak strain is greater than that in the other two directions while having a better energy gathering effect. Based on the findings, the new charge structure with directional energy concentration has a damage reduction effect. Furthermore, the material of aluminum slotted pipe is found to be better than PVC slotted pipe, whereas the material of PVC slotted pipe is better than kraft paper slotted pipe in achieving directional rock breaking.

Influence of tai chi softball on body composition and bone density / Influência do tai chi softball sobre a composição corporal e a densidade óssea / Influencia del tai chi softball en la composición corporal y la densidad ósea

ABSTRACT Introduction Tai Chi Softball fully reflects the most complete and coherent concept of Tai Chi exercise, round and smooth, natural and continuous, and is very suitable for the daily exercise of middle-aged and elderly people. Objective Explore the effect of Tai Chi Softball exercise on body shape and bone mineral density of middle-aged and elderly women. Methods 45 volunteers were recruited and divided into a Tai Chi Softball group and a control group; the Tai Chi Softball group was guided by professional trainers to perform Tai Chi Softball exercises for six months. The control group did not perform Tai Chi Softball exercises and tested various physical indicators for comparison. Results The weight and BMI of middle-aged and elderly women showed a decreasing trend. The abdominal and arm skinfold measurements were significantly different from those before the experiment (P < 0.01). Body fat percentage decreased significantly, and muscle weight increased, showing statistical significance (P < 0.05). Conclusion Tai Chi Softball exercise can alleviate the rapid decline in bone mineral density and bone mineral content in middle-aged and elderly women. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

RESUMO Introdução O Tai Chi Softball reflete integralmente o conceito mais completo e coerente do exercício de Tai Chi, redondo e suave, natural e contínuo, sendo muito adequado para o exercício diário de pessoas de meia-idade e idosas. Objetivo Explorar o efeito do exercício de Tai Chi Soft Ball na composição corporal e densidade mineral óssea de mulheres de meia-idade e idosas. Métodos 45 voluntários foram recrutados e divididos em um grupo de Tai Chi Softball e um grupo de controle, o grupo de Tai Chi Softball foi orientado por treinadores profissionais para realizar exercícios de Tai Chi Softball por 6 meses. O grupo de controle não realizou o exercício de Tai Chi Softball, e testou vários indicadores físicos para comparação. Resultados O peso e o IMC das mulheres de meia-idade e idosas mostraram uma tendência decrescente. Entre elas, as medidas de dobra cutânea do abdômen e braço foram significativamente diferentes daquelas anteriores à experiência (P < 0,01). O percentual de gordura corporal diminuiu significativamente e o peso muscular aumentou, apresentando significância estatística (P<0,05). Conclusão O exercício de Tai Chi Softball pode aliviar o rápido declínio da densidade mineral óssea e do conteúdo mineral ósseo em mulheres de meia-idade e idosas. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.

RESUMEN Introducción El Tai Chi Softball refleja plenamente el concepto más completo y coherente del ejercicio de Tai Chi, redondo y suave, natural y continuo, y es muy adecuado para el ejercicio diario de las personas de mediana edad y mayores. Objetivo Explorar el efecto del ejercicio de Tai Chi Softball sobre la composición corporal y la densidad mineral ósea de mujeres de mediana edad y mayores. Métodos Se reclutaron 45 voluntarias y se dividieron en un grupo de Tai Chi Softball y un grupo de control, el grupo de Tai Chi Softball fue guiado por entrenadores profesionales para realizar ejercicios de Tai Chi Softball durante 6 meses. El grupo de control no realizó el ejercicio, y se sometió a varios indicadores físicos para su comparación. Resultados El peso y el IMC de las mujeres de mediana edad y de edad avanzada mostraron una tendencia a la baja. Entre ellos, las medidas de los pliegues cutáneos abdominales y del brazo fueron significativamente diferentes de las anteriores al experimento (P < 0,01). El porcentaje de grasa corporal disminuyó significativamente y el peso muscular aumentó, mostrando significancia estadística (P < 0,05). Conclusión El ejercicio de Tai Chi Softball puede aliviar el rápido descenso de la densidad mineral ósea y del contenido mineral óseo en mujeres de mediana edad y mayores. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.

Non-ST elevation myocardial infarction induced by carbon monoxide poisoning: A case report.

RATIONALE: Acute myocardial infarction is a rare complication of carbon monoxide poisoning. there is often no chest pain and other typical manifestations. We report a patient with mild carbon monoxide poisoning who had acute dyspnea as the earliest symptom and was later diagnosed with non-ST elevation myocardial infarction (NSTEMI) and acute left heart failure. PATIENT CONCERNS: A 73-year-old woman complained of dizziness and fatigue with shortness of breath after carbon monoxide intoxication. DIAGNOSES: This patient had a clear history of carbon monoxide poisoning, acute respiratory distress, bilateral lung dry and moist rale, chest X-ray showed bilateral pulmonary edema, Electrocardiograph indicated general depression of the ST segment of the leads in the chest, cardiac troponin I (CTNI) increased progressively, cardiac ultrasonography indicated abnormal ventricular wall movement, coronary angiography suggested left main trunk and 3-vessel lesions, suggesting diagnosis acute carbon monoxide poisoning, acute coronary syndrome, acute left heart failure. INTERVENTIONS: She was treated with a high concentration of oxygen, an inhibitor of platelet aggregation (aspirin plus clopidogrel), an anticoagulant (low molecular weight heparin), an antimicrobial (ceftizoxime), an expectorant (mucosolvan), diuresis (furosemide and spironolactone), and myocardial support (Metoprolol). Coronary angiography and stent placement were performed 8 days later. OUTCOME: On the 10th day after onset of the condition, echocardiography was performed, which showed that cardiac function was improved. Mild segmental wall motion abnormality was observed on echocardiography. After 14 days, the patient had recovered well and was discharged without chest tightness, chest pain, dizziness, headache, or unresponsiveness. LESSONS: This case suggests that the symptoms of carbon monoxide poisoning are complex and diverse. It can be manifested as a primary hypoxic symptom, or cause the exacerbation of underlying diseases due to hypoxia. Therefore, patients with carbon monoxide poisoning should actively seek comprehensive cardiac examination to ensure early diagnosis. Whenever necessary, coronary angiography and stent implantation should be performed to improve the likelihood of the patient's survival.

Analysis of combined detection of N-terminal pro-B-type natriuretic peptide and left ventricular ejection fraction in heart function in patients with acute CO poisoning.

OBJECTIVE: N-terminal pro-B-type natriuretic peptide (NT-proBNP) has been used in the evaluation on heart function in many heart diseases. However, little is known in patients with acute carbon monoxide poisoning (ACOP). Left ventricular ejection fraction (LVEF) can be applied as a preliminary test method to measure the left ventricular function. In the present study, we investigate the clinical significance of NT-proBNP combined with LVEF on heart function in 68 patients with ACOP. METHODS: A total of 68 ACOP patients hospitalized were divided into 3 groups: the mild, the moderate, and the severe group. During the same period, 30 healthy volunteers were chosen to represent the control group. The serum NT-proBNP was immediately measured and LVEF was monitored by an echocardiogram within 24 hours after admission. All data were analyzed and compared for the groups investigated. RESULTS: N-terminal pro-B-type natriuretic peptide showed a significant increase and LVEF a considerable decrease in all 3 clinic groups (P < .01) when compared with the control group. Levels of NT-proBNP are increased and levels of LVEF are decreased when the clinic group changed from mild, moderate, to severe. N-terminal pro-B-type natriuretic peptide is negatively correlated with LVEF (r = -0.955, P = .045). Combined detection of NT-proBNP and LVEF in the diagnosis of heart function was found to be more sensitive compared with the single index after ACOP (χ(2) = 14.636, P < .05). CONCLUSION: There are an increased level of NT-proBNP and a decrease of LVEF, which represents a clear sign of heart malfunction by ACOP. Combined NT-proBNP and LVEF detection technique has a significant advantage in the diagnosis of patients with myocardial contraction function damage after ACOP.

Diffusion tensor imaging for predicting the clinical outcome of delayed encephalopathy of acute carbon monoxide poisoning.

OBJECTIVE: The aim of the present study was to determine the relationship between neuropsychiatric outcomes and diffusion tensor imaging (DTI) in patients with delayed encephalopathy after acute carbon monoxide poisoning (DEACMP). METHODS AND MATERIALS: 66 patients and 60 healthy controls were included in this study. Median fractional anisotropy (FA) of the white matter (WM) bilaterally was compared between patients and healthy controls. The Glasgow Outcome Scale (GOS) was assessed at 4-6 months following DEACMP. The association between the GOS score and FA variables was explored using the Spearman rank correlation. RESULTS: The FA values in WM were reduced in patients with DEACMP compared with those in the volunteers. Of the 66 patients, 21 (31.8%) achieved a good outcome (GOS-5), 26 (36.4%) had moderate disability (GOS-4), 14 (21.2%) had severe disability (GOS-3), 5 (7.6%) were in a vegetative state (GOS-2), and none of the patients died (GOS-1). The FA values in the WM in patients with DEACMP correlated significantly with GOS. CONCLUSION: DTI may be a valuable tool for assessing the severity of brain injury and may be a predictor of outcome in patients with delayed encephalopathy of acute carbon monoxide poisoning. DTI may be a valuable tool for assessing the severity of tissue injury and may be a predictor of outcome.

[Quantitative study of therapeutic efficacy on early intervention of hyperbaric oxygen to model of steroid-induced avascular osteonecrosis of femoral head by multi-slice perfusion imaging].

OBJECTIVE: To quantitatively evaluate the hemodynamic status in animal models of steroid-induced avascular osteonecrosis of femoral head (SANFH) by multislice CT (MSCT) perfusion imaging, and estimate the therapeutic efficacy on early intervention of hyperbaric oxygen (HBO) to improve the region blood flow (rBF) of ischemic femoral head. METHODS: Forty-eight New Zealand male rabbits were injected with Escherichia coli endotoxin and methyl-prednisolone to establish SANFH models and then divided into 3 subgroups to undergo MSCT to measure the rBF, regional blood volume (rBV), and mean transit time (MTT) to obtain perfusion maps at the femoral head epiphysis, metaphysic, and neck of femur, and then were killed to undergo histological examination of the bilateral femoral heads 2, 4, and 6 weeks later respectively (Groups M(2), M(4), and M(6)). Twenty-four rabbits underwent HOB treatment after the second injection of E. c. endotoxin for 1-3 courses respectively (Groups H(1), H(2), and H(3)), and then underwent MSCT and pathological examination as described above. Eight rabbits were used as controls (Group N). RESULTS: (1) The rBF values of Groups M(2), M(4), and M(6) were all significantly lower than that of Group N (P < 0.001, < 0.001, and < 0.002). The rBF value of femoral head epiphysis of Group M(2) was remarkably lower than that of Group N, decreased to the lowest in Group M(4), and re-increased in Group M(6). The rBV value demonstrated similar change pattern in femoral head epiphysis. The MTT values of Groups M(2) and M(4) were longer than that of Group N, and then re-decreased in Group M(6). (2) It did differ significantly between the perfusion data of different femoral head anatomic regions in Groups M(2), M(4), M(6) and N (rBF: F = 52.190, P < 0.001; rBV: F = 42.677, P < 0.001; MTT: F = 3.09, P = 0.048). The changes of the perfusion data in femoral head epiphysis were more significant than those in other anatomic regions. (3) There were no statistically significant differences in the rBF value of the femoral head epiphysis and metaphysis (F = 2.081, P = 0.115; F = 1.142, P = 0.341), in the rBV value of the femoral metaphysis and neck of femur (F = 2.642, P = 0.059; F = 1.568, P = 0.209), and the MTT value of all the anatomic regions (F = 1.111, P = 0.347) among Groups H(1), H(2), H(3), and N. The rBF values of Groups H(1), H(2), and H(3) were statistically higher than those of the corresponding phase model groups (all P < 0.05). CONCLUSIONS: Able to detect hemodynamic status of femoral head, MSCT perfusion imaging technique may be used in the early detection of SANFH. Early intervention of HBO therapy can improve the blood perfusion of femoral head.

Clinical study on the related markers of blood coagulation in the patients with ANFH after SARS.

The aim of this research was to investigate the blood coagulation function in the patients with avascular necrosis of the femoral head (ANFH) after severe acute respiratory syndrome (SARS). The expression of CD31, CD61, CD62p, CD63 and PAC-1 on platelet membrane was measured respectively by flowcytometry, and the plasma prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT) and fibrinogen (Fbg) were measured by blood clotting instrument in 26 patients with ANFH after SARS and in 17 healthy adults. The expression of CD31, CD61, CD 62p, CD63 and PAC-1 on platelet membrane in 26 patients was all lower than that in 17 healthy subjects (P < 0.01). The levels of PT, APTT, TT and Fbg in 26 patients were all normal. There is no significant difference (P > 0.05) in those markers between patients and 17 healthy adults. The blood may not be in hypercoagulable state in patients with ANFH after SARS.

[Prevention and treatment of complications after duodenopancreatectomy].

OBJECTIVE: To analyze the causes of the complications following duodenopancreatectomy and their prevention and treatment. METHODS: The clinical data of 36 cases receiving duodenopancreatectomy during the last decade were analyzed, including 13 cases of ampullary carcinoma, 8 cases of carcinoma of the pancreas head, 8 cases of distal cholangiocarcinoma, and 7 cases of carcinoma of the duodenal papilla. RESULTS: Complications occurred in 6 cases after duodenopancreatectomy including pancreatic fistula in 3 cases, bile duct fistula in 1 case, abdominal cavity hemorrhage in 1 case, and alimentary tract hemorrhage in 1 case, with an incidence rate of postoperative complications of 16.7%; and death occurred in 2 cases. CONCLUSION: Adequate measures should be taken to reduce such complications as pancreatic fistula, bile duct fistula, abdominal cavity hemorrhage, alimentary tract hemorrhage and abdominal cavity infection, and these measures include nutritional support, careful operation in the surgery with adequate drainage, and careful observation and nursing after the surgery.