Effects of 'in-service' conditions - mimicked hull roughness ranges and biofilms - on the surface and the hydrodynamic characteristics of foul-release type coatings.

To develop a better understanding of 'in-service' performance of modern marine coatings, this study explored the combined effects of different roughness ranges of foul-release coating (FRC) and light biofouling (slime) on the surface, boundary layer and drag characteristics under a range of 'in-service' conditions. Natural and laboratory biofilms were grown dynamically on FRC panels by exposing panels in facilities dedicated to realistic fouling culture. The boundary layer experiments were conducted in a circulating water tunnel. Boundary layer similarity-law scaling was used to predict the combined effects of coating roughness and biofilms on the added frictional resistance (% ΔCF) and added required effective power  (%ΔPE ) for a benchmark KRISO container ship (KCS) and a bulk carrier. The increase in  %ΔPE  due to the presence of biofilms on commercial FRC is estimated to be between 7% and 16% depending on the biofilm type, biofilm thickness and percentage coverage. Significant increases in effective power are estimated for non-fouling control primers with heavy fouling. Moreover, the paper suggests updated roughness allowances ( ΔCF ) for two vessel types assuming FRCs on their hulls with more representative hull roughness ranges and fluffy biofilms.

Application of antibiotics in treatment of coronavirus disease 2019 in a designated hospital. / 某2019å† çŠ¶ç— æ¯’ç— æ•‘æ²»ä¸“ç§‘åŒ»é™¢æŠ—èŒè¯ç‰©ä½¿ç”¨æƒ å†µ.

OBJECTIVES: To explore the prescribing habits of doctors, and to provide basis for rational use of antibiotics in clinical practice via investigating and analyzing the applications of antibiotics in treatment of coronavirus disease 2019 (COVID-19) in the designated hospital. METHODS: Specification, quantity, amount, defined daily dose system (DDDs), defined daily dose consumption (DDDc), antibiotics use density (AUD), composition, frequency of use, combined use of antibacterial drugs used in the hospital were analyzed between Feb. 2020 and Mar. 2020. RESULTS: A total of 25 antibiotic drugs in 12 categories were used. The total cost for antibiotic drugs was 1 million 238 thousand yuan, in which quinolone accounts for 48%, the third generation cephalosporin/lactamase inhibitors accounts for 15.86%, antifungals accounts for 14.17%, oxazolidone accounts for 13.46%, and carbapenms account for 12.73%. The top three drugs of DDDs and AUD were moxifloxacin hydrochloride tablets, moxifloxacin hydrochloride and sodium chloride injection, cefoperazone sodium and sulbactam sodium for injection. The proportion of patients who had been used more than two kinds of antibiotics was 22.36%. CONCLUSIONS: Broad-spectrum, high-potency antibiotics are used at the beginning of COVID-19 treatment. The varieties of antibiotics meet the requirements of the management of antibiotics, and the utilization rate of antibiotics and the cost proportion of antibiotics in COVID-19 patients are within a reasonable range.In the future, for the treatment of COVID-19, we should continue to summarize the experience, improve the strategies, and rationally apply antibiotics on the basis of guidelines.

Application of antibiotics in treatment of coronavirus disease 2019 in a designated hospital / 中南大学学报(医学版)

OBJECTIVES@#To explore the prescribing habits of doctors, and to provide basis for rational use of antibiotics in clinical practice via investigating and analyzing the applications of antibiotics in treatment of coronavirus disease 2019 (COVID-19) in the designated hospital.@*METHODS@#Specification, quantity, amount, defined daily dose system (DDDs), defined daily dose consumption (DDDc), antibiotics use density (AUD), composition, frequency of use, combined use of antibacterial drugs used in the hospital were analyzed between Feb. 2020 and Mar. 2020.@*RESULTS@#A total of 25 antibiotic drugs in 12 categories were used. The total cost for antibiotic drugs was 1 million 238 thousand yuan, in which quinolone accounts for 48%, the third generation cephalosporin/lactamase inhibitors accounts for 15.86%, antifungals accounts for 14.17%, oxazolidone accounts for 13.46%, and carbapenms account for 12.73%. The top three drugs of DDDs and AUD were moxifloxacin hydrochloride tablets, moxifloxacin hydrochloride and sodium chloride injection, cefoperazone sodium and sulbactam sodium for injection. The proportion of patients who had been used more than two kinds of antibiotics was 22.36%.@*CONCLUSIONS@#Broad-spectrum, high-potency antibiotics are used at the beginning of COVID-19 treatment. The varieties of antibiotics meet the requirements of the management of antibiotics, and the utilization rate of antibiotics and the cost proportion of antibiotics in COVID-19 patients are within a reasonable range.In the future, for the treatment of COVID-19, we should continue to summarize the experience, improve the strategies, and rationally apply antibiotics on the basis of guidelines.

An experimental investigation into the surface and hydrodynamic characteristics of marine coatings with mimicked hull roughness ranges.

There are limited scientific data on contributors to the added drag of in-service ships, represented by modern-day coating roughness and biofouling, either separately or combined. This study aimed to gain an insight into roughness and hydrodynamic performance of typical coatings under in-service conditions of roughened ships' hull surfaces. Comprehensive and systematic experimental data on the boundary layer and drag characteristics of antifouling coating systems with different finishes are presented. The coating types investigated were linear-polishing polymers, foul-release and controlled-depletion polymers. The data were collected through state-of-the-art equipment, including a 2-D laser Doppler velocimetry (LDV) system for hydrodynamic data in a large circulating water tunnel. Three coating systems were first applied on flat test panels with 'normal' finishes in the first test campaign to represent coating applications under idealised laboratory conditions. In order to address more realistic roughness conditions, as typically observed on ships' hulls, 'low' and 'high' roughness densities were introduced into the same types of coating, in the second test campaign. The data collected from the first test campaign served as the baseline to demonstrate the effect on the surface roughness and hydrodynamic drag characteristics of these coating types as a result of 'in-service' or 'severely flawed' coating application scenarios. Data collected on coatings with a range of in-service surface conditions provided a basis to establish correlation between the surface roughness characteristics and hydrodynamic performance (roughness function). The findings of the study indicate that the estimations of drag penalties based on well-applied, relatively smooth coating conditions underestimate the importance of hull roughness, which although undesirable, is commonplace in the world's commercial fleet.