Digital Twin Geometry for Fibrous Air Filtration Media

Computational modeling of air filtration is possible by replicating nonwoven nanofibrous meltblown or electrospun filter media with digital representative geometry. This article presents a methodology to create and modify randomly generated fiber geometry intended as a digital twin replica of fibrous filtration media. Digital twin replicas of meltblown and electrospun filter media are created using Python scripting and Ansys SpaceClaim. The effect of fiber stiffness, represented by a fiber relaxation slope, is analyzed in relation to resulting filter solid volume fraction and thickness. Contemporary air filtration media may also be effectively modeled analytically and tested experimentally in order to yield valuable information on critical characteristics, such as overall resistance to airflow and particle capture efficiency. An application of the Single Fiber Efficiency model is incorporated in this work to illustrate the estimation of performance for the generated media with an analytical model. The resulting digital twin fibrous geometry compares well with SEM imagery of fibrous filter materials. This article concludes by suggesting adaptation of the methodology to replicate digital twins of other nonwoven fiber mesh applications for computational modeling, such as fiber reinforced additive manufacturing and composite materials.

PRESSURE DISTRIBUTION DUE TO STERN TAB DEFLECTION AT MODEL SCALE

Trim tabs form an important part of motion control systems on high-speed watercraft. By altering the pitch angle, significant improvements in propulsion efficiency can be achieved by reducing overall resistance. For a ship in heavy seas, trim tabs can also be used to reduce structural loads by changing the vessel orientation in response to encountered waves. In this study, trials have been conducted in the University of Tasmania hydraulics laboratory using a closed- circuit water tunnel to measure model scale trim tab forces. The model scale system replicates the stern tabs on the full- scale INCAT Tasmania 112 m high-speed wave-piercer catamaran. The model was designed for total lift force measurement and pressure tappings allowed for pressures to be measured at fixed locations on the underside of the hull and tab. This investigation examines the pressures at various flow velocities and tab deflection angles for the case of horizontal vessel trim. A simplified two-dimensional CFD model of the hull and tab has also been analysed using ANSYS CFX software. The results of model tests and CFD indicate that the maximum pressure occurs in the vicinity of the tab hinge and that the pressure distribution is long-tailed in the direction forward of the hinge. This accounts for the location of the resultant lift force, which is found to act forward of the tab hinge.

Improving membrane filtration performance through time series analysis

For ultrafiltration, and membrane filtration more generally, the quantitative determination of the modes of fouling remains a subject of great interest. Herein an integral method for determining the modes from a time series of volumetric flux $$J\left(t\right)$$ J t is given and illustrated with previously published filtration data of bergamot juice (Ruby-Figueroa et al (J Membr Sci 524:108-116, 2017)). The integral method of fouling analysis has the potential to become the cornerstone of a robust empirical process. In addition to determining, in a clear-cut manner, the point at which there is a switch from one mode to another, the robust methodology yields characteristic $$J\left(t\right)$$ J t equation for each mode that are an excellent fit to the data. The emphasis is upon the creation of a robust methodology which is best viewed as being a semi-empirical method that is indicative of the modes of fouling. For the example chosen, the initial 4 L/m2 generates some pore blocking after which the main mode of fouling is cake build-up. The variation of overall resistance with time is also informative and analysis of this series was used to check the result for the initial phase of fouling as determined from the time series of volumetric flux. A comparison against the ARIMA (Autoregressive integrated moving average) method, which has never been previously undertaken, is given herein. The integral method of fouling analysis was found to be superior, in part because of the quality of fit to the data and in part because it enables one to establish whether the initial fouling is different in character from the subsequent fouling. Having this information can improve membrane selection and overall membrane filtration performance.

Chronic fistula to rabbit cecum microbiome study

The purpose of this work is to approve a device for studying the microbiome of the gastrointestinal tract of mammals. The study of the quantitative and qualitative composition of the digestive tract microbiota is one of the promising directions in metagenomics. Knowledge obtained about the organization of microbiocenosis genome, the determination of species composition and study of metabolic relationships between its representatives not only expand the understanding of its role in the process of evolution, speciation and breeding but also provide a scientifically substantiated basis for targeting changes in the microbiome to form a phenotype (optimization of feed bioconversion, increasing overall resistance, etc.). Scientific novelty. For the first time, the main characteristics of cellulolytic bacteria isolated from the chyme of the rabbit cecum were isolated, cultured and described through a chronic fistula. Methods. In order to carry out research aimed to study mammalian microbiome and its correction, the need arises to develop methods of obtaining microbiome samples from experimental animals. To obtain access to the chyme of the cecum in 7 rabbits for up to 3 months the chronic fistulas developed in Scientific Research Institute of Fur-Bearing Animal Breeding and Rabbit Breeding n. a. V. A. Afanas’ev were installed. No negative manifestations were observed in the animals after installation of the fistulas, no changes in appetite were detected, and complete healing of the skin wound was determined on the 9th day. Diagnostic laparotomies performed 3 months after fistula placement revealed no pathological processes in any of the studied animals. Results. Characteristics of cellulolytic bacteria of the rabbit cecum Butirivibrio fibrisolvens and Ruminococcus flavefaciens were studied. Data on their enzymatic effects on dietary components, fermentation products, digestion and formation of organic substances and chemical compounds are presented.

Improving Membrane Filtration Performance Through Time Series Analysis

For ultrafiltration, and membrane filtration more generally, the quantitative determination of the modes of fouling remains a subject of great interest. Herein a clear method for determining the modes from a time series of volumetric flux J(t) is given and illustrated with previously published filtration data of bergamot juice (Journal of Membrane Science 524 (2017) 108-116). The emphasis is upon the robust methodology which is of general applicability and offers a straightforward approach to the modelling of flux decline. The method is best viewed as being an empirical method that determines the point at which there is a switch from one mode to another is determined in a clear-cut manner and it yields excellent equations for J(t). For the example chosen, the initial 4 L/m2 generates some pore blocking after which the main mode of fouling is cake build-up. The variation of overall resistance with time is also informative and analysis of this series was used to check the result for the initial phase of fouling as determined from the time series of volumetric flux. A strength of the integral approach is that it enables one to establish whether the initial fouling is different in character from the subsequent fouling. Having this information can improve membrane selection and overall membrane filtration performance.

Effect of Connection Resistance between Cyclones and Backpass on Furnace Solids Suspension Density Profile and Circulation Rates in CFB

The connection section between cyclones and backpass is an important configuration in multi-cyclone circulating fluidized bed boilers (CFB). In this work, the resistance coefficient of different connection modes, and connection resistance distribution from each cyclone outlet to backpass (connection branch) in one mode are defined and calculated, in order to investigate their effects on furnace solids suspension density distribution and circulation rates. Three connection modes with different overall resistance coefficients were tested experimentally and analyzed by a 1.5-dimensional model in a four-cyclone scaling CFB apparatus. Both experimental and theoretical results show that, with larger overall resistance of a connection, there are more solids suspended in the furnace bottom and fewer in the top section. The investigation of the C-type connection has revealed that when the branch resistance of the connection decreases from branch No. 1–4, the solids suspension density and circulation rate from corresponding solids recycle loops (No. 1–4) increase. Moreover, the non-uniformity of connection branch resistance distribution will lead to uneven lateral solids suspension density distribution and circulation rates allocation. This effect is enhanced by growing superficial velocity.

Minimum inhibitory concentrations of commonly used antibiotics against Helicobacter Pylori: A multicenter study in South China

Aim To determine the minimum inhibitory concentrations (MICs) of commonly used antibiotics against Helicobacter Pylori (H. pylori) in South China and compare their resistance rates by using EUCAST breakpoints and other breakpoints. Methods Patients who had not previously received H. pylori treatment in clinical centers in South China were enrolled in this study from 2017 to 2020. Gastric biopsies were obtained for H. pylori culture. The MICs of amoxicillin (AMX), clarithromycin (CLA), metronidazole (MTZ), levofloxacin (LEV), tetracycline (TET) and furazolidone (FZD) were tested by broth microdilution method and assessed by two different breakpoints. ATCC43504 standard strain served as a control. Results A total of 208 H. pylori strains were isolated from patients’ biopsy samples. The MICs of AMX, CLA, MTZ, LEV, TET and FZD for H. pylori were 0.0156-256mg/L (MIC50 0.125mg/L, MIC90 4mg/L), 0.0156- >256 mg/L (MIC50 0.0312mg/L, MIC90 64mg/L), 0.0156- >256mg/L (MIC50 8mg/L, MIC90 256mg/L), 0.0156-256mg/L (MIC50 0.25mg/L, MIC90 16mg/L), 0.0156-256mg/L (MIC50 0.0625mg/L, MIC90 4mg/L), and 0.0156- >256mg/L (MIC50 0.0312mg/L, MIC90 2mg/L), respectively. The MICs of AMX, CLA, MTZ, LEV, TET and FZD for ATCC43504 strain were 0.25mg/L, 0.0625mg/L, 64mg/L, 0.5mg/L, 1mg/L and 0.25mg/L, respectively. The resistance rate of FZD was 11.05%. The overall resistance rates according to EUCAST breakpoints and other breakpoints were 57.21% and 14.90% for AMX (p<0.001), 38.94% and 38.94% for CLA (p = 1), 39.42% and 50.96% for MTZ (p<0.001), 12.98% and 10.58% for TET (p = 0.025), 35.10% and 35.10% for LEV (p = 1), respectively. Conclusions Our results demonstrate that AMX, FZD, and TET, but not MTZ, CLR or LEV, showed good anti-H. pylori activity in vitro in South China. When different breakpoints were used, similar results were found with CLA, and LEV, but not with AMX, MTZ, or TET.

Antimicrobial resistance and molecular epidemiological typing of Neisseria gonorrhoeae isolates from Kyrgyzstan in Central Asia, 2012 and 2017

Background Gonorrhoea and antimicrobial resistance (AMR) in Neisseria gonorrhoeae are significant public health concerns globally. Nearly no gonococcal AMR data are available from Central Asia, and no data from Kyrgyzstan has been published. We examined, for the first time, AMR and molecular epidemiology of N. gonorrhoeae isolates cultured in Kyrgyzstan in 2012 and 2017, in order to inform refinements of the Kyrgyz national gonorrhoea management guidelines. Methods N. gonorrhoeae isolates cultured in 2012 (n = 84) and 2017 (n = 72) in Kyrgyzstan were examined. MICs of nine antimicrobials were determined using Etest and, where available, clinical breakpoints from the EUCAST were applied. N. gonorrhoeae multiantigen sequence typing (NG-MAST) was also performed. Results The overall resistance levels were high to ciprofloxacin (88.5%), tetracycline (56.9%), benzylpenicillin (39.1%), and kanamycin (4.7%). Resistance to cefixime (0.6%, n = 1 isolate), azithromycin (0.6%, n = 1), and gentamicin (0.6%, n = 1) was rare. No resistance to ceftriaxone or spectinomycin was found. However, the proportion of isolates with decreased susceptibility (MIC = 0.125 mg/L) to ceftriaxone and cefixime was 12.8 and 11.5%, respectively. Gonococcal isolates were assigned 69 sequence types, of which 52 (75.4%) were new. Conclusions The gonococcal population in Kyrgyzstan in 2012 and 2017 showed a high genetic diversity. Ceftriaxone, 500–1000 mg, in combination with azithromycin 2 g or doxycycline, particularly when chlamydial infection has not been excluded, should be recommended as empiric first-line treatment. Spectinomycin 2 g could be an alternative treatment, and given with azithromycin 2 g if pharyngeal gonorrhoea has not been excluded. Fluoroquinolones, aminoglycosides, benzylpenicillin, or tetracyclines should not be used for empiric treatment of gonorrhoea in Kyrgyzstan. Timely updating and high compliance to national gonorrhoea treatment guidelines based on quality-assured AMR data is imperative. Expanded and improved gonococcal AMR surveillance in Kyrgyzstan is crucial.

Antibiotic resistance and plasmid analysis of Enterobacteriaceae isolated from retail meat in Lagos Nigeria

Background The presence of antibiotic resistant microorganisms in food is of great concern globally. This research was carried out to detect and characterize plasmid carriage and profiles among members of Enterobacteriaceae from different meat types in Nigeria. Method From a total of 80 meat samples comprising of mutton,pork, beef and chicken, organisms belonging to the family Enterobacteriaceae wereisolated by standard procedures and identified by API 20E system. Antibiotics susceptibilities testing (AST) againstselected classes of antimicrobial agents and plasmid extraction was carried outby disc diffusion and alkaline lysis methods respectively. Results One-hundred and ten Enterobacteriaceae were isolated,species identification revealed isolates belonging to 7 genera comprising of Escherichia, Enterobacter, Klebsiella,Citrobacter, Proteus, Salmonella and Serratia. Overall resistance of theorganisms to amoxycillin/clavulanic acid was 91 (82.7%), streptomycin 85(75.7%) and perfloxacin 74 (67.2%) while ofloxacin had the highestsusceptibility rate (91.8%). Plasmids profiling revealed ranges of plasmids from1 to 3 copies with estimated sizes range of 700bp to 1.1kb among E. coli, K. pneumoniae, E. aerogenesand Proteus mirabilis. All theisolates with plasmids were multidrug resistant and were isolated from chicken excepta strain of E. coli from pork whichharboured a single plasmid copy suggesting these meat as reservoirs forantibiotic resistant bacteria. Conclusion Our findings revealed high level of meat contamination with antibioticresistant Enterobacteriaceae harbouring resistant plasmids. An integratedsurveillance system and safety practice must be ensured among the processorsand retailers.

Two Different Inoculation Methods Unveiled the Relative Independence of DON Accumulation in Wheat Kernels from Disease Severity on Spike after Infection by Fusarium Head Blight

Fusarium head blight (FHB) causes wheat yield loss and mycotoxin (deoxynivalenol, DON) accumulation in wheat kernel. Developing wheat cultivars with overall resistance to both FHB spread within a spike and DON accumulation in kernels is crucial for ensuring food security and food safety. Here, two relatively novel inoculation methods, bilateral floret inoculation (BFI) and basal rachis internode injection (BRII), were simultaneously employed to evaluate disease severity and DON content in kernels in a segregating population of recombinant inbred lines (RILs) developed from Ning 7840 (carrying Fhb1) and Clark (without Fhb1). Under both inoculation methods, four contrasting combinations of disease severity and DON content were identified: high severity/high DON (HSHD), high severity/low DON (HSLD), low severity/high DON (LSHD) and low severity/low DON (LSLD). Unexpectedly, the BRII method clearly indicated that disease severity was not necessarily relevant to DON concentration. The effects of Fhb1 on disease severity, and on DON concentrations, agreed very well across the two methods. Several lines carrying Fhb1 showed extremely higher severity and (or) DON content under both inoculation methods. The “Mahalanobis distance” (MD) method was used to rate overall resistance of a line by inclusion of both disease severity and DON content over both methods to select LSLD lines.