The objective of this study was to determine the effect of supplementation with a protected fat source on the productive response, metabolic environment and physiological indicators in Holstein cows under heat stress ...The objective of this study was to determine the effect of supplementation with a protected fat source on the productive response, metabolic environment and physiological indicators in Holstein cows under heat stress conditions during a 12-week experimental period. Thirty Holstein cows were distributed in 15 blocks by parity (2.0 ± 1.1), days in milk (182 ± 80) and milk production (29.4 ± 5.7 kg·day<sup>-</sup><sup>1</sup>) at the beginning of the trial and randomly assigned within each block to the following treatments (diets): SPF: supplementation with protected fat or WPF: without supplementation with protected fat. All the cows were kept in a dry-lot where they were given a partial mixed ration (PMR) ad libitum while in the milking parlor they received individual supplementation depending on the treatment. The SPF diet contained 4.0 kg·day<sup>-</sup><sup>1</sup> concentrate in pellet form + 0.6 kg·day<sup>-1</sup> ground corn grain + 0.7 kg·day<sup>-</sup><sup>1</sup> protected fat, while the WPF diet was similar to that offered in SPF, but the protected fat was isoenergetically replaced by ground corn grain. The fat supplement contained fats of animal and vegetable origin and microencapsulation was used for its preparation. Total dry matter and metabolic energy intakes were similar (p > 0.05) between treatments. Fat corrected milk (4% FCM) production was higher (p = 0.04), while energy corrected milk and fat productions tended (p = 0.06) to be higher in cows from the SPF group, without effects (p > 0.05) on the rest of the milk production and composition parameters. These results could be attributed to an improvement in the efficiency of the use of the energy consumed. Protected fat supplementation neither modified the metabolic profile, nor reduced the respiratory rate and body temperature of heat-stressed cows. Future research is needed to explain this latter result.展开更多
The objective of this study was to investigate the effect of Palm Oil By-pass Fat (POBF) on milk composition of early lactation Holstein during dry season, 24 postpartum Holstein (1 d-14 d) were selected and align...The objective of this study was to investigate the effect of Palm Oil By-pass Fat (POBF) on milk composition of early lactation Holstein during dry season, 24 postpartum Holstein (1 d-14 d) were selected and align to two groups according to CRD experimental design; each group included 12 Holstein cows. The control received by-pass fat 0 g/h.d, the experimental group received by-pass fat 300 g/h.d. The results shown, DMI and yield of milk did not be affected with supplementation of by-pass fat, however, milk protein increased by 6.71%, milk fat increased by 8.16%, lactose increased by 0.22%, SNF increased by 1.98%, TS increased 4.08%; digestibility of diet protein decreased by 6.62%, digestibility of EE decreased by 7.96%, digestibility of NDF and ADL decreased by 1.36%, 8.97% respectively, digestibility of DM and OM decreased by 4.42, 3.07 percentage units; amount of C4-C17 milk fatty acids showed a decreased tendency, that of CIs-C22 showed an increased tendency, the milk CLA increased significantly (P 〈 0.01). To sum up, supplementation of by-pass fat for early lactation Holstein is an important measure to balance energy and sustain milk yield and quality.展开更多
Background: To compare the neuropsychological consequences after carotid artery stenting (CAS) and extracranial-intracranial by-pass (EC-IC by-pass). Methods: A total of 43 patients referred to CAS, 32 patients referr...Background: To compare the neuropsychological consequences after carotid artery stenting (CAS) and extracranial-intracranial by-pass (EC-IC by-pass). Methods: A total of 43 patients referred to CAS, 32 patients referred to EC-IC by-pass and 43 control subjects were enrolled in the study. Neuropsychologic testing was performed before and three months after procedure. A paired Student t test was used to compare neuropsychologic test scores at baseline and three months after procedure in each group. Cognitive changes in a three-month follow-up were not normally distributed and compared among/between groups with Kruskal-Wallis test. Results: Three months after the treatment both the CAS and EC-IC by-pass groups showed improved cognitive performance compared to baseline, whereas the same improvement wasn’t seen in the control group. The scores from Activities of Daily Living also improved in all three groups in a three-month follow-up, and EC-IC group presented a more distinct increase in daily life abilities comparing to the other two groups. Conclusions: CAS and EC-IC by-pass in patients with a carotid or intracranial stenosis may result in cognitive improvement three months after surgery.展开更多
There was organized a 2×2 factorial type experience in which it has been aimed the influence of forage/concentrates ratio and the effect of supplementing the ratio with full fat soya by-pass (FFS) on the produc...There was organized a 2×2 factorial type experience in which it has been aimed the influence of forage/concentrates ratio and the effect of supplementing the ratio with full fat soya by-pass (FFS) on the production performance and carcass fatty acid profile of fattening lambs. 32 Tsigai lambs were divided into 4 groups and were fed with 2 different diets regarding the forage/concentrates ratio (35/65 and 65/35, on a DM basis), containing or not 5% FFS (full fat soya treated with formaldehyde 12.5%). Including FFS in diet and the ratios rich in concentrates determined a significant improvement in weight gain (P〈0.01), in the degree of food recovery and in fatty acid profile from the carcass. It has been significantly increased (P〈0.01) the weight of polyunsaturated fatty acids (PUFA) from intramuscular fat (longissimus dorsi-LD and femoral biceps-FB) and the deposit fat (subcutaneous-SC and perirenal-PR) and decreased the proportion of saturated (SFA) and monounsaturated fatty acids (MUFA). Most significant differences were recorded about PUFA from Omega-3 series (C18:3 n-3, EPA C22:3 n-3, DPA and DHA) and CLA isomers (conjugated linolenic acid: C 18:2 C9, tl I+C 18:2 t10, C 12). The best profile of fatty acids, considered in light of the influence on human health (high concentration of Omega 3 fatty acids and CLA and low in SFA) was established in LD, for lambs fed with diets high in concentrates and which contained FFS (HC/S).展开更多
Myocardial infarction is a major cause of death and disability worldwide and myocardial infarct size is a major determinant of prognosis. Early and successful restoration of myocardial reperfusion following an ischemi...Myocardial infarction is a major cause of death and disability worldwide and myocardial infarct size is a major determinant of prognosis. Early and successful restoration of myocardial reperfusion following an ischemic event is the most effective strategy to reduce final infarct size and improve clinical outcome,but reperfusion may induce further myocardial damage itself. Development of adjunctive therapies to limit myocardial reperfusion injury beyond opening of the coronary artery gains increasing attention. A vast number of experimental studies have shown cardioprotective effects of ischemic and pharmacological conditioning,but despite decades of research,the translation into clinical effects has been challenging. Recently published clinical studies,however,prompt optimism as novel techniques allow for improved clinical applicability. Cyclosporine A,the GLP-1 analogue exenatide and rapid cooling by endovascular infusion of cold saline all reduce infarct size and may confer clinical benefit for patients admitted with acute myocardial infarcts. Equally promising,three follow-up studies of the effect of remote ischemic conditioning(RIC) show clinical prognostic benefit in patients undergoing coronary surgery and percutaneous coronary intervention. The discovery that RIC canbe performed noninvasively using a blood pressure cuff on the upper arm to induce brief episodes of limb ischemia and reperfusion has facilitated the translation of RIC into the clinical arena. This review focus on novel advances in adjunctive therapies in relation to acute and elective coronary procedures.展开更多
AIM: For patients of periampullary carcinoma found to be unresectable at the time of laparotomy, surgical palliation is the primary choice of treatment. Satisfactory palliation to maximize the quality of life with low...AIM: For patients of periampullary carcinoma found to be unresectable at the time of laparotomy, surgical palliation is the primary choice of treatment. Satisfactory palliation to maximize the quality of life with low morbidity and mortality is the gold standard for a good procedure.Our aim is to explore such a procedure as an alternative to the traditional ones.METHODS: A modified double-bypass procedure is performed by, in addition to the usual gastrojejunostomy,implanting a mushroom catheter from the gall bladder into the jejunum through the interposed stomach as an internal drainage. A retrospective review was performed including 22 patients with incurable periampullary carcinomas who underwent this surgery.RESULTS: Both jaundice and impaired liver function improved significantly after surgery. No postoperative deaths, cholangitis, gastrojejunal, biliary anastomotic leaks, recurrent jaundice or late gastric outlet obstruction occurred. Delayed gastric emptying occurred in two patients. The total surgical time was 150±26 min. The estimated blood loss was 160±25 mL. The mean length of hospital stay after surgery was 22±6 d. The mean survival was 8 mo (range 1.5-18 mo).CONCLUSION: In patients of unresectable periampullary malignancies, stomach-interposed cholecystogastrojejunostomy is a safe, simple and efficient technique for palliation.展开更多
Objectives: The main steps for physiologic type reconstruction in 50 complicated corrosive strictures of upper alimentary tract are presented. Methods: In successive developed gastric outlet and esophageal strictures ...Objectives: The main steps for physiologic type reconstruction in 50 complicated corrosive strictures of upper alimentary tract are presented. Methods: In successive developed gastric outlet and esophageal strictures a limited Billroth I resection (in 9) or conversion a prior precolic GEA in such anastomosis (in 5) and middle or total gastrectomies (in 3) were performed. A second stage substernal by-pass with isoperistaltic transverse colon segment was done 6 - 12 weeks later. In all but one instances the graft was implanted high in the gastric stump. In extensive burned and retracted such lesion (in 3) a similar by-pass was carried out but the lower anastomosis was done with the not involved prepyloric segement. In concomittant antropyloric and esophageal strictures in 11 young, good risk patients, a limited Billroth I resction and simultaneous colonic bypass was used. In case of accompanied respiratory fistula (in 4) exclusion by-pass was useful for both lesions. The associated pyloric stricture (in 3) was solved at the same time. Side-to-end pharyngocolostomy was used in 4 high thoracocervical strictures. In 8 previously perforated strictures the by-ass was performed 2 months later. Reults: The overall mortality was 4%. The postoperative morbidity was low (8%). All cervical leaks closed spontaneously. Particular late complications required revisional surgery in 12, 5% of cases. Conclusion: In complicated corrosive strictures (esophageal, gastric, fistulas) limited Billoth I resection, isoperistaltic colon by-pass with high gastrocolic anastomosis, good gastric drainage and maintenance of the duodenum in gastrointestinal continuity are the main factors to achieve the best functional results.展开更多
<em>Objective</em>: In order to take a decision about the revascularization approach to be adopted, it is of fundamental importance to determine whether coronary artery stenoses induce ischemia or not. An ...<em>Objective</em>: In order to take a decision about the revascularization approach to be adopted, it is of fundamental importance to determine whether coronary artery stenoses induce ischemia or not. An index, named (Fractional Flow Reserve), based on pressure measurements has been proposed to this aim and is usually interpreted in terms of flows. The objective of this work is to compute simultaneously pressures and flow rates in the coronary network of patients with three-vessel disease, in order to study more precisely the relationship between these two quantities. <em>Approach</em>: 22 patients have been included in the study. Some pressure and flow rate measurements were collected during by-pass surgery. These clinical data allow determining parameters for a patient’s specific model, based on the electric/hydraulic analogy. Collateral pathways are included in the model, as well as the severity of the disease and the impact of revascularization. <em>Main Results</em>: For patients with stenoses on LAD, LCx, LMCA and occlusion of the RCA, the flow rate delivered to the right territory is of course a function of the aortic pressure, the left stenoses severity, and the pressure distal to the thrombosis. But it mainly depends on the capillary and collateral resistances, and on the proportion between them. Abnormal microvascular hemodynamics, may be present in patients with non-hemodynamic significant lesions as assessed by the pressure ratio. Complete revascularization with the 3 grafts is demonstrated to be fully justified. The direction of collateral flows may be reversed, depending on the pressure gradient. In any case, they remain low and become negligible when the 3 grafts are operating. <em>Significance</em>: Surgical decision based only on pressure measurements may miss some real hemodynamic problems due to the considered stenosis. This risk is even greater in case of serial stenoses.展开更多
Ventricular fibrillation seen just after declamping of the aorta is an undesirable condition causing myocardial injury. To return to normal rhythm, often internal shocks are applied. But defibrillation itself can also...Ventricular fibrillation seen just after declamping of the aorta is an undesirable condition causing myocardial injury. To return to normal rhythm, often internal shocks are applied. But defibrillation itself can also contribute to myocardial injury. So prevention of fibrillation is more important than treatment. 236 patients undergoing coronary artery by-pass surgery were included in this retrospective clinical study. 144 of those patients were operated using modified St. Thomas’ Hospital cardioplegic solution, for stopping the heart. In the other 92 patients, plegisol cardioplegic solution was used. We compared the two groups for the development of ventricular fibrilation after declamping of the aorta. In the modified St. Thomas’ Hospital group, ventricular fibrillation after declamping of the aorta was seen less frequently, this being statistically significant (22.2% vs. 52.2%, p = 0.026). This study shows that the modified St.Thomas’ Hospital cardioplegic solution is preferred for avoiding ventricular fibrillation occuring just after declamping of the aorta.展开更多
The transition process of the boundary layer developing over a flat plate with elevated inlet Free Stream Turbulence Intensity(FSTI)has been studied by means of Large Eddy Simulation(LES).To this purpose,four cases wi...The transition process of the boundary layer developing over a flat plate with elevated inlet Free Stream Turbulence Intensity(FSTI)has been studied by means of Large Eddy Simulation(LES).To this purpose,four cases with different inflow disturbances have been tested varying the magnitude and the length scale of turbulence.LES has been performed by using the finite-volume ANSYS Fluent code.The computational domain,which was constituted by a rectangular domain with a zero thickness plate,was based on an ERCOFTAC test case in order to provide a validation with a well-known set of data by comparing the boundary layer integral parameters and mean and fluctuating streamwise velocity profiles.The four cases were discussed within the paper by looking at classical statistical properties as well as advanced post-processing tools.It was shown that the decrease in the free stream turbulence level postpones the transition location,whereas the variation of the integral length scale has a very low influence on the distribution of the time-mean flow properties.Proper Orthogonal Decomposition(POD)has been applied to the instantaneous LES flow fields in order to provide a statistical representation of the structures responsible for transition and their response to free-stream turbulence intensity and length scale.The presence of vortical filaments parallel to the wall,typically referred as boundary layer streaks,is clearly identified;their characteristic dimensions and how they change as a function of FSTI properties were analyzed within the paper.展开更多
Cement kiln co-processing techniques have been developed in the past 20 years in China,and more than 60 factories now use fermentation,screening,and gasification pre-treatment techniques to coprocess municipal solid w...Cement kiln co-processing techniques have been developed in the past 20 years in China,and more than 60 factories now use fermentation,screening,and gasification pre-treatment techniques to coprocess municipal solid waste(MSW).There three complete MSW pre-treatment techniques,coprocessing procedures,and environmental risk assessments have been described in few publications.In this study,we assessed the effectiveness of each technique.The results suggested that the pollutant content released by each pre-treatment technology was lower than the emission standard.To reveal the mechanisms of pollutant migration and enrichment,the substances in the kiln and kiln products are investigated.The input of co-processing materials(Co-M)produced by fermentation caused formation of polychlorinated dibenzo-p-dioxins and dibenzoftiran(PCDD/Fs)in the bypass flue gas(By-gas)in excess of the regulatory standard.The Co-M input produced by the screening and gasifier technologies caused the total organic carbon(TOC)concentration to exceed the standard.In addition,the NOx,TOC,and PCDD/Fs in the By-gas exceeded the regulatory standard.Raw meal was the primary chlorine and heavy metals input stream,and clinker(CK)and cement kiln dust(CKD)accounted for>90%of the total chlorine output stream.Flue gas and CKD were the primary volatile heavy metal(Hg)output streams.Greater than 70%of the semi-volatile heavy metals(Cd,Pb,T1 and Se)distributed in hot raw meal and bypass cement kiln dust.The low-volatility heavy metals were concentrated in the CK.These results indicated that co-processing techniques used in China still require improvement.展开更多
文摘The objective of this study was to determine the effect of supplementation with a protected fat source on the productive response, metabolic environment and physiological indicators in Holstein cows under heat stress conditions during a 12-week experimental period. Thirty Holstein cows were distributed in 15 blocks by parity (2.0 ± 1.1), days in milk (182 ± 80) and milk production (29.4 ± 5.7 kg·day<sup>-</sup><sup>1</sup>) at the beginning of the trial and randomly assigned within each block to the following treatments (diets): SPF: supplementation with protected fat or WPF: without supplementation with protected fat. All the cows were kept in a dry-lot where they were given a partial mixed ration (PMR) ad libitum while in the milking parlor they received individual supplementation depending on the treatment. The SPF diet contained 4.0 kg·day<sup>-</sup><sup>1</sup> concentrate in pellet form + 0.6 kg·day<sup>-1</sup> ground corn grain + 0.7 kg·day<sup>-</sup><sup>1</sup> protected fat, while the WPF diet was similar to that offered in SPF, but the protected fat was isoenergetically replaced by ground corn grain. The fat supplement contained fats of animal and vegetable origin and microencapsulation was used for its preparation. Total dry matter and metabolic energy intakes were similar (p > 0.05) between treatments. Fat corrected milk (4% FCM) production was higher (p = 0.04), while energy corrected milk and fat productions tended (p = 0.06) to be higher in cows from the SPF group, without effects (p > 0.05) on the rest of the milk production and composition parameters. These results could be attributed to an improvement in the efficiency of the use of the energy consumed. Protected fat supplementation neither modified the metabolic profile, nor reduced the respiratory rate and body temperature of heat-stressed cows. Future research is needed to explain this latter result.
文摘The objective of this study was to investigate the effect of Palm Oil By-pass Fat (POBF) on milk composition of early lactation Holstein during dry season, 24 postpartum Holstein (1 d-14 d) were selected and align to two groups according to CRD experimental design; each group included 12 Holstein cows. The control received by-pass fat 0 g/h.d, the experimental group received by-pass fat 300 g/h.d. The results shown, DMI and yield of milk did not be affected with supplementation of by-pass fat, however, milk protein increased by 6.71%, milk fat increased by 8.16%, lactose increased by 0.22%, SNF increased by 1.98%, TS increased 4.08%; digestibility of diet protein decreased by 6.62%, digestibility of EE decreased by 7.96%, digestibility of NDF and ADL decreased by 1.36%, 8.97% respectively, digestibility of DM and OM decreased by 4.42, 3.07 percentage units; amount of C4-C17 milk fatty acids showed a decreased tendency, that of CIs-C22 showed an increased tendency, the milk CLA increased significantly (P 〈 0.01). To sum up, supplementation of by-pass fat for early lactation Holstein is an important measure to balance energy and sustain milk yield and quality.
文摘Background: To compare the neuropsychological consequences after carotid artery stenting (CAS) and extracranial-intracranial by-pass (EC-IC by-pass). Methods: A total of 43 patients referred to CAS, 32 patients referred to EC-IC by-pass and 43 control subjects were enrolled in the study. Neuropsychologic testing was performed before and three months after procedure. A paired Student t test was used to compare neuropsychologic test scores at baseline and three months after procedure in each group. Cognitive changes in a three-month follow-up were not normally distributed and compared among/between groups with Kruskal-Wallis test. Results: Three months after the treatment both the CAS and EC-IC by-pass groups showed improved cognitive performance compared to baseline, whereas the same improvement wasn’t seen in the control group. The scores from Activities of Daily Living also improved in all three groups in a three-month follow-up, and EC-IC group presented a more distinct increase in daily life abilities comparing to the other two groups. Conclusions: CAS and EC-IC by-pass in patients with a carotid or intracranial stenosis may result in cognitive improvement three months after surgery.
文摘There was organized a 2×2 factorial type experience in which it has been aimed the influence of forage/concentrates ratio and the effect of supplementing the ratio with full fat soya by-pass (FFS) on the production performance and carcass fatty acid profile of fattening lambs. 32 Tsigai lambs were divided into 4 groups and were fed with 2 different diets regarding the forage/concentrates ratio (35/65 and 65/35, on a DM basis), containing or not 5% FFS (full fat soya treated with formaldehyde 12.5%). Including FFS in diet and the ratios rich in concentrates determined a significant improvement in weight gain (P〈0.01), in the degree of food recovery and in fatty acid profile from the carcass. It has been significantly increased (P〈0.01) the weight of polyunsaturated fatty acids (PUFA) from intramuscular fat (longissimus dorsi-LD and femoral biceps-FB) and the deposit fat (subcutaneous-SC and perirenal-PR) and decreased the proportion of saturated (SFA) and monounsaturated fatty acids (MUFA). Most significant differences were recorded about PUFA from Omega-3 series (C18:3 n-3, EPA C22:3 n-3, DPA and DHA) and CLA isomers (conjugated linolenic acid: C 18:2 C9, tl I+C 18:2 t10, C 12). The best profile of fatty acids, considered in light of the influence on human health (high concentration of Omega 3 fatty acids and CLA and low in SFA) was established in LD, for lambs fed with diets high in concentrates and which contained FFS (HC/S).
文摘Myocardial infarction is a major cause of death and disability worldwide and myocardial infarct size is a major determinant of prognosis. Early and successful restoration of myocardial reperfusion following an ischemic event is the most effective strategy to reduce final infarct size and improve clinical outcome,but reperfusion may induce further myocardial damage itself. Development of adjunctive therapies to limit myocardial reperfusion injury beyond opening of the coronary artery gains increasing attention. A vast number of experimental studies have shown cardioprotective effects of ischemic and pharmacological conditioning,but despite decades of research,the translation into clinical effects has been challenging. Recently published clinical studies,however,prompt optimism as novel techniques allow for improved clinical applicability. Cyclosporine A,the GLP-1 analogue exenatide and rapid cooling by endovascular infusion of cold saline all reduce infarct size and may confer clinical benefit for patients admitted with acute myocardial infarcts. Equally promising,three follow-up studies of the effect of remote ischemic conditioning(RIC) show clinical prognostic benefit in patients undergoing coronary surgery and percutaneous coronary intervention. The discovery that RIC canbe performed noninvasively using a blood pressure cuff on the upper arm to induce brief episodes of limb ischemia and reperfusion has facilitated the translation of RIC into the clinical arena. This review focus on novel advances in adjunctive therapies in relation to acute and elective coronary procedures.
文摘AIM: For patients of periampullary carcinoma found to be unresectable at the time of laparotomy, surgical palliation is the primary choice of treatment. Satisfactory palliation to maximize the quality of life with low morbidity and mortality is the gold standard for a good procedure.Our aim is to explore such a procedure as an alternative to the traditional ones.METHODS: A modified double-bypass procedure is performed by, in addition to the usual gastrojejunostomy,implanting a mushroom catheter from the gall bladder into the jejunum through the interposed stomach as an internal drainage. A retrospective review was performed including 22 patients with incurable periampullary carcinomas who underwent this surgery.RESULTS: Both jaundice and impaired liver function improved significantly after surgery. No postoperative deaths, cholangitis, gastrojejunal, biliary anastomotic leaks, recurrent jaundice or late gastric outlet obstruction occurred. Delayed gastric emptying occurred in two patients. The total surgical time was 150±26 min. The estimated blood loss was 160±25 mL. The mean length of hospital stay after surgery was 22±6 d. The mean survival was 8 mo (range 1.5-18 mo).CONCLUSION: In patients of unresectable periampullary malignancies, stomach-interposed cholecystogastrojejunostomy is a safe, simple and efficient technique for palliation.
文摘Objectives: The main steps for physiologic type reconstruction in 50 complicated corrosive strictures of upper alimentary tract are presented. Methods: In successive developed gastric outlet and esophageal strictures a limited Billroth I resection (in 9) or conversion a prior precolic GEA in such anastomosis (in 5) and middle or total gastrectomies (in 3) were performed. A second stage substernal by-pass with isoperistaltic transverse colon segment was done 6 - 12 weeks later. In all but one instances the graft was implanted high in the gastric stump. In extensive burned and retracted such lesion (in 3) a similar by-pass was carried out but the lower anastomosis was done with the not involved prepyloric segement. In concomittant antropyloric and esophageal strictures in 11 young, good risk patients, a limited Billroth I resction and simultaneous colonic bypass was used. In case of accompanied respiratory fistula (in 4) exclusion by-pass was useful for both lesions. The associated pyloric stricture (in 3) was solved at the same time. Side-to-end pharyngocolostomy was used in 4 high thoracocervical strictures. In 8 previously perforated strictures the by-ass was performed 2 months later. Reults: The overall mortality was 4%. The postoperative morbidity was low (8%). All cervical leaks closed spontaneously. Particular late complications required revisional surgery in 12, 5% of cases. Conclusion: In complicated corrosive strictures (esophageal, gastric, fistulas) limited Billoth I resection, isoperistaltic colon by-pass with high gastrocolic anastomosis, good gastric drainage and maintenance of the duodenum in gastrointestinal continuity are the main factors to achieve the best functional results.
文摘<em>Objective</em>: In order to take a decision about the revascularization approach to be adopted, it is of fundamental importance to determine whether coronary artery stenoses induce ischemia or not. An index, named (Fractional Flow Reserve), based on pressure measurements has been proposed to this aim and is usually interpreted in terms of flows. The objective of this work is to compute simultaneously pressures and flow rates in the coronary network of patients with three-vessel disease, in order to study more precisely the relationship between these two quantities. <em>Approach</em>: 22 patients have been included in the study. Some pressure and flow rate measurements were collected during by-pass surgery. These clinical data allow determining parameters for a patient’s specific model, based on the electric/hydraulic analogy. Collateral pathways are included in the model, as well as the severity of the disease and the impact of revascularization. <em>Main Results</em>: For patients with stenoses on LAD, LCx, LMCA and occlusion of the RCA, the flow rate delivered to the right territory is of course a function of the aortic pressure, the left stenoses severity, and the pressure distal to the thrombosis. But it mainly depends on the capillary and collateral resistances, and on the proportion between them. Abnormal microvascular hemodynamics, may be present in patients with non-hemodynamic significant lesions as assessed by the pressure ratio. Complete revascularization with the 3 grafts is demonstrated to be fully justified. The direction of collateral flows may be reversed, depending on the pressure gradient. In any case, they remain low and become negligible when the 3 grafts are operating. <em>Significance</em>: Surgical decision based only on pressure measurements may miss some real hemodynamic problems due to the considered stenosis. This risk is even greater in case of serial stenoses.
文摘Ventricular fibrillation seen just after declamping of the aorta is an undesirable condition causing myocardial injury. To return to normal rhythm, often internal shocks are applied. But defibrillation itself can also contribute to myocardial injury. So prevention of fibrillation is more important than treatment. 236 patients undergoing coronary artery by-pass surgery were included in this retrospective clinical study. 144 of those patients were operated using modified St. Thomas’ Hospital cardioplegic solution, for stopping the heart. In the other 92 patients, plegisol cardioplegic solution was used. We compared the two groups for the development of ventricular fibrilation after declamping of the aorta. In the modified St. Thomas’ Hospital group, ventricular fibrillation after declamping of the aorta was seen less frequently, this being statistically significant (22.2% vs. 52.2%, p = 0.026). This study shows that the modified St.Thomas’ Hospital cardioplegic solution is preferred for avoiding ventricular fibrillation occuring just after declamping of the aorta.
文摘The transition process of the boundary layer developing over a flat plate with elevated inlet Free Stream Turbulence Intensity(FSTI)has been studied by means of Large Eddy Simulation(LES).To this purpose,four cases with different inflow disturbances have been tested varying the magnitude and the length scale of turbulence.LES has been performed by using the finite-volume ANSYS Fluent code.The computational domain,which was constituted by a rectangular domain with a zero thickness plate,was based on an ERCOFTAC test case in order to provide a validation with a well-known set of data by comparing the boundary layer integral parameters and mean and fluctuating streamwise velocity profiles.The four cases were discussed within the paper by looking at classical statistical properties as well as advanced post-processing tools.It was shown that the decrease in the free stream turbulence level postpones the transition location,whereas the variation of the integral length scale has a very low influence on the distribution of the time-mean flow properties.Proper Orthogonal Decomposition(POD)has been applied to the instantaneous LES flow fields in order to provide a statistical representation of the structures responsible for transition and their response to free-stream turbulence intensity and length scale.The presence of vortical filaments parallel to the wall,typically referred as boundary layer streaks,is clearly identified;their characteristic dimensions and how they change as a function of FSTI properties were analyzed within the paper.
基金This work was financially supported by the National Basic Research Program of China(2019YFC1906900)Chinese Central Public Welfare Research Project(2019YSKY-016).
文摘Cement kiln co-processing techniques have been developed in the past 20 years in China,and more than 60 factories now use fermentation,screening,and gasification pre-treatment techniques to coprocess municipal solid waste(MSW).There three complete MSW pre-treatment techniques,coprocessing procedures,and environmental risk assessments have been described in few publications.In this study,we assessed the effectiveness of each technique.The results suggested that the pollutant content released by each pre-treatment technology was lower than the emission standard.To reveal the mechanisms of pollutant migration and enrichment,the substances in the kiln and kiln products are investigated.The input of co-processing materials(Co-M)produced by fermentation caused formation of polychlorinated dibenzo-p-dioxins and dibenzoftiran(PCDD/Fs)in the bypass flue gas(By-gas)in excess of the regulatory standard.The Co-M input produced by the screening and gasifier technologies caused the total organic carbon(TOC)concentration to exceed the standard.In addition,the NOx,TOC,and PCDD/Fs in the By-gas exceeded the regulatory standard.Raw meal was the primary chlorine and heavy metals input stream,and clinker(CK)and cement kiln dust(CKD)accounted for>90%of the total chlorine output stream.Flue gas and CKD were the primary volatile heavy metal(Hg)output streams.Greater than 70%of the semi-volatile heavy metals(Cd,Pb,T1 and Se)distributed in hot raw meal and bypass cement kiln dust.The low-volatility heavy metals were concentrated in the CK.These results indicated that co-processing techniques used in China still require improvement.