Manure management is an essential component of dairy production. Nutrient-laden, field-applied dairy manure often serves as a fertilizer source, but can also pose environmental threats if not properly managed. The Haa...Manure management is an essential component of dairy production. Nutrient-laden, field-applied dairy manure often serves as a fertilizer source, but can also pose environmental threats if not properly managed. The Haak dairy farm, located in Decatur, Arkansas, was granted a permit by the Arkansas Department of Environmental Quality (ADEQ) to employ a unique method in treating and storing cattle manure generated during the milking process. This method includes minimizing water use in wash water, dry scraping solids to combine with sawdust for composting and pumping effluent underground into a sloped concrete basin that serves as secondary solid separator before transporting the manure effluent into an interception trench and an adjacent grassed field to facilitate manure nutrient uptake and retention. The Arkansas Discovery Farm program (ADF) is conducting research to evaluate the environmental performance of the dairy’s milk center wash water treatment system (MCWW) by statistical analysis, characterization of phosphorus (P) migration in soil downslope from the inception trench, temperature measurements, and nutrient analysis of a stored dry stack manure/sawdust mixture. Goals included determining possible composting effectiveness along with comparisons to untreated dairy manure and quantifying the use of on-farm water. Results from this research demonstrated that: 1) The MCWW was effective at retaining manure-derived nutrients and reducing field nutrient migration as the MCWW interception trench had significantly higher total nitrogen (TN) (804.2 to 4.1), total phosphorus (TP) (135.6 to 1.5), and water extractable phosphorus (WEP) (55.0 to 1.0) concentrations in milligrams per liter (mg⋅L<sup>-1</sup>) than the downhill freshwater pond respectively;2) temperature readings of the manure dry stack indicated heightened levels of microbial and thermal activity, but did not reach a standard composting temperature of 54°C;3) manure dry stack nutrient content was typically higher than untreated dairy manure when measured on a “dry basis” in ppm, but was lower on an “as is basis” in ppm and kg/metric ton;and 4) water meter readings showed that the greatest use of on-farm water was for farm-wide cattle drinking (18.77), followed by water used in the milking center (3.45) and then followed by human usage (0.02) measured in cubic meters per day (m<sup>3</sup>⋅d<sup>-1</sup>). These results demonstrate that practical innovations in agricultural engineering and environmental science, such as the Haak dairy’s manure treatment system, can effectively reduce environmental hazards that accompany the management of manure at this dairy operation.展开更多
In the design theory of scroll profiles for refrigeration scroll compressor,a mechanism principle of scroll profiles based on the center of natural temporal involutes and meshing region is presented,by which the perfo...In the design theory of scroll profiles for refrigeration scroll compressor,a mechanism principle of scroll profiles based on the center of natural temporal involutes and meshing region is presented,by which the performance characteristics of the various involutes are studied. Profiles type selection is very important for scroll compressor. Through analyzing the characteristic geometry,natural meshing mechanism is discovered in the study of scrolls. And a novel method for scroll profiles based on natural meshing mechanism is proposed. The result shows that the meshing region angle of odd regular polygon involutes is half of the characteristic-geometry exterior angle,and that of even regular polygon involutes is equal to the exterior angle to the moment. The corresponding meshing region angle is reduced increasingly with the increase of the edge number of characteristic geometry. The performance characteristics of scroll compressor tend towards the best correspondingly. Aiming at the existing problems of profile design for scrolls,we developed a novel methodology to study scroll profile. Originality research was done for the further study of scroll profile. It is the fundamentality factor representing essence character of scroll profiles function itself.展开更多
<b>Introduction:</b> <i>Burkholderia cepacia</i> is a non-fermenting emergent bacterium common in nosocomial infections and can cause life-threatening infections whose multidrug resistance make...<b>Introduction:</b> <i>Burkholderia cepacia</i> is a non-fermenting emergent bacterium common in nosocomial infections and can cause life-threatening infections whose multidrug resistance makes them a serious threat in hospitals. The aim of this study was to determine the prevalence of <i>B. cepacia</i> infections during nosocomial infections at Libreville University teaching hospital. <b>Methodology:</b> In this cross-sectional study, lasting 19 months, 412 blood cultures were analyzed. The BacT/ALERT 3D (Biomerieux, France) was used to detect the positivity of blood culture flasks and the Viteck 2 compact (Biomerieux, France) for the identification of germs and the study of their susceptibility to antibiotics. <b>Results:</b> Our study population consisted of 412 patients. The sex-ratio M/F was 1.06 in favor of the male gender (n = 201, 51%). The age of the patients varied between 0 and 82 years. The bacteremia of <i>B. cepacia</i> mainly affected children under 15 years of age with a prevalence of 7% (n = 28). The pediatric ward was more represented with a frequency of 36% (n = 10). The antibiotic sensitivity profile showed high resistance of 100% for aminoglycosides (amikacin, tobramycin, and gentamycin), tetracycline, beta-lactams (Amoxicillin, Imipenem, Ticarcillin, Cefoxitin and Cefotaxime), and ciprofloxacin. However, four molecules were active on <i>B. cepacia</i> (Levofloxacin 100%, Trimethoprim + sulfamethoxazole 92.3%, ceftazidime 80% and cefepime 35%). <b>Conclusion:</b> Ultimately, infection and multi-resistance due to <i>Burkholderia cepacia</i> calls for a review of hospital hygiene in the pediatric ward and a review of antibiotic therapy in young children.展开更多
文摘Manure management is an essential component of dairy production. Nutrient-laden, field-applied dairy manure often serves as a fertilizer source, but can also pose environmental threats if not properly managed. The Haak dairy farm, located in Decatur, Arkansas, was granted a permit by the Arkansas Department of Environmental Quality (ADEQ) to employ a unique method in treating and storing cattle manure generated during the milking process. This method includes minimizing water use in wash water, dry scraping solids to combine with sawdust for composting and pumping effluent underground into a sloped concrete basin that serves as secondary solid separator before transporting the manure effluent into an interception trench and an adjacent grassed field to facilitate manure nutrient uptake and retention. The Arkansas Discovery Farm program (ADF) is conducting research to evaluate the environmental performance of the dairy’s milk center wash water treatment system (MCWW) by statistical analysis, characterization of phosphorus (P) migration in soil downslope from the inception trench, temperature measurements, and nutrient analysis of a stored dry stack manure/sawdust mixture. Goals included determining possible composting effectiveness along with comparisons to untreated dairy manure and quantifying the use of on-farm water. Results from this research demonstrated that: 1) The MCWW was effective at retaining manure-derived nutrients and reducing field nutrient migration as the MCWW interception trench had significantly higher total nitrogen (TN) (804.2 to 4.1), total phosphorus (TP) (135.6 to 1.5), and water extractable phosphorus (WEP) (55.0 to 1.0) concentrations in milligrams per liter (mg⋅L<sup>-1</sup>) than the downhill freshwater pond respectively;2) temperature readings of the manure dry stack indicated heightened levels of microbial and thermal activity, but did not reach a standard composting temperature of 54°C;3) manure dry stack nutrient content was typically higher than untreated dairy manure when measured on a “dry basis” in ppm, but was lower on an “as is basis” in ppm and kg/metric ton;and 4) water meter readings showed that the greatest use of on-farm water was for farm-wide cattle drinking (18.77), followed by water used in the milking center (3.45) and then followed by human usage (0.02) measured in cubic meters per day (m<sup>3</sup>⋅d<sup>-1</sup>). These results demonstrate that practical innovations in agricultural engineering and environmental science, such as the Haak dairy’s manure treatment system, can effectively reduce environmental hazards that accompany the management of manure at this dairy operation.
基金supported by the National Natural Science Foundation of China(Grant No.50805149)China Postdoctoral Science Foundation(Grant No.20090450166)the Open Foundation of State Key Lab of Mechanical Transmission.
文摘In the design theory of scroll profiles for refrigeration scroll compressor,a mechanism principle of scroll profiles based on the center of natural temporal involutes and meshing region is presented,by which the performance characteristics of the various involutes are studied. Profiles type selection is very important for scroll compressor. Through analyzing the characteristic geometry,natural meshing mechanism is discovered in the study of scrolls. And a novel method for scroll profiles based on natural meshing mechanism is proposed. The result shows that the meshing region angle of odd regular polygon involutes is half of the characteristic-geometry exterior angle,and that of even regular polygon involutes is equal to the exterior angle to the moment. The corresponding meshing region angle is reduced increasingly with the increase of the edge number of characteristic geometry. The performance characteristics of scroll compressor tend towards the best correspondingly. Aiming at the existing problems of profile design for scrolls,we developed a novel methodology to study scroll profile. Originality research was done for the further study of scroll profile. It is the fundamentality factor representing essence character of scroll profiles function itself.
文摘<b>Introduction:</b> <i>Burkholderia cepacia</i> is a non-fermenting emergent bacterium common in nosocomial infections and can cause life-threatening infections whose multidrug resistance makes them a serious threat in hospitals. The aim of this study was to determine the prevalence of <i>B. cepacia</i> infections during nosocomial infections at Libreville University teaching hospital. <b>Methodology:</b> In this cross-sectional study, lasting 19 months, 412 blood cultures were analyzed. The BacT/ALERT 3D (Biomerieux, France) was used to detect the positivity of blood culture flasks and the Viteck 2 compact (Biomerieux, France) for the identification of germs and the study of their susceptibility to antibiotics. <b>Results:</b> Our study population consisted of 412 patients. The sex-ratio M/F was 1.06 in favor of the male gender (n = 201, 51%). The age of the patients varied between 0 and 82 years. The bacteremia of <i>B. cepacia</i> mainly affected children under 15 years of age with a prevalence of 7% (n = 28). The pediatric ward was more represented with a frequency of 36% (n = 10). The antibiotic sensitivity profile showed high resistance of 100% for aminoglycosides (amikacin, tobramycin, and gentamycin), tetracycline, beta-lactams (Amoxicillin, Imipenem, Ticarcillin, Cefoxitin and Cefotaxime), and ciprofloxacin. However, four molecules were active on <i>B. cepacia</i> (Levofloxacin 100%, Trimethoprim + sulfamethoxazole 92.3%, ceftazidime 80% and cefepime 35%). <b>Conclusion:</b> Ultimately, infection and multi-resistance due to <i>Burkholderia cepacia</i> calls for a review of hospital hygiene in the pediatric ward and a review of antibiotic therapy in young children.
