Numerical study on the effect of circumferential position of ultrasonic transducers on ultrasonic cross-correlation flowmeter performance under asymmetric air flow profile

There are several ultrasonic flowmeter technologies such as transient time, cross-correlation, Doppler and etc. The performance of different types of ultrasonic flowmeters under disturbed flow profile due to elbow at upstream has been well studied recently except the cross-correlation type. The ultrasonic cross-correlation flowmeter (UCCF) has different mechanism of flow measurement in comparison with other types of ultrasonic flowmeters that strongly requires its own studies. In case of disturbed flow profile in pipe, due to asymmetrical velocity profile, the UCCF accuracy and required calibration factor are strongly dependent on the circumferential position of ultrasonic transducers on the pipe. Study on UCCF transducers circumferential position and specifying transducers proper position could incredibly improve the UCCF accuracy. The effect of transducers circumferential position on the accuracy in both single path and multipath has not been investigated for a UCCF so far. In this work, Computational Fluid Dynamics (CFD) simulations were conducted using turbulence model of RSM (Reynolds Stress Model) Stress-ω to simulate the asymmetrical air flow profile inside the elbow and the connected straight pipe in order to study the effect of circumferential position of transducers on calibration factor for special type of ultrasonic flowmeters ,UCCF, at different Reynolds numbers and various locations of flowmeter, for the first time. Moreover, the effects of Reynolds numbers and the flowmeter distances from the elbow on the calibration factor were analyzed. Finally, based on calculated calibration factors at different transducer circumferential positions, the best transducers arrangement at different flowmeter locations were proposed for single and multipath cross-correlation flowmeter. Also, in multipath ultrasonic cross correlation flowmeter, the optimum number of transducers were investigated.

Calculation of geometric flow profile correction factor for ultrasonic flow meter using semi-3D simulation technique

Due to the operating conditions, the flow profile within the ultrasonic flowmeters is not usually uniform. In order to consider the effects of non-uniformity, the flow profile correction factor (FPCF) can be implemented in the flow rate calculation process. Considering this, the measured velocity in each acoustic path can be converted to the average velocity. Various techniques have been used so far to simulate ultrasonic flowmeters and to calculate FPCF, which have often employed only CFD simulation without considering the effect of the flow on the acoustic wave movement inside the flowmeter. However, 3D acoustic simulation requires a very high mesh, especially when the diameter of the meter is high or the distance between the ultrasonic transducers is relatively long. In this work, a semi-3D simulation technique is used, through employing which, the FPCF for a commercial DN200 ultrasonic meter is calculated with a reasonable accuracy for different inlet flow velocities. Using this technique can significantly reduce the computational space and time.

Emergence of non-Candida albicans species: Epidemiology, phylogeny and fluconazole susceptibility profile

OBJECTIVE

Non-Candida albicans (NCA) species now account for a significant part of clinical candidiasis worldwide. In the present study, epidemiology and antifungal susceptibility profile of NCA isolated from various forms of candidiasis were studied with special focus on their phylogenetic relationship by ITS sequencing.

PATIENTS AND METHODS

Seventy-nine NCA isolates were isolated from skin and nail scrapings (67.0%), vaginal discharges (8.8%), blood (8.8%), sputa (5.0%), urine (5.0%), oral swabs (2.6%), biopsy and eye tumor, each (1.4%). These isolates were identified by morphological, biochemical and molecular (ITS sequencing) techniques. In vitro antifungal susceptibility of the isolates to fluconazole (FCZ) was tested according to the CLSI method (M27-S4).

RESULTS

Among a total number of 79 cases of proven NCA infections, C. parapsilosis (36.8%) was the most prevalent species followed by C. glabrata (32.9%), C. orthopsilosis (11.4%), C. tropicalis (8.9%), C. krusei (5.0%) and C. guilliermondii (5.0%). The susceptibility to FCZ was assessed for C. parapsilosis (96.5%), C. orthopsilosis (88.9%), C. tropicalis (85.7%) and C. guilliermondii (50.0%). C. glabrata and C. krusei isolates were not susceptible to FCZ. NCA species were distributed in various phylogenetic clades including C. glabrata (1), C. tropicalis (3), C. parapsilosis (6) and C. orthopsilosis, C. krusei and C. guilliermondii (each 2).

CONCLUSION

C. parapsilosis and C. glabrata were the most predominant NCA species involve in the etiology of candidiasis. C. orthopsilosis was reported from superficial candidiasis. Taken together, our results further substantiate the increasing importance of the involvement of NCA species in the etiology of candidiasis.

Effect of Magnetospirillum gryphiswaldense on serum iron levels in mice

BACKGROUND AND OBJECTIVES

The Magnetotactic bacterium Magnetospirillumgryphiswaldense (MSR-1) mineralizes the magnetite (Fe(3) O(4)) crystals and organizes a highly ordered intracellular structure, called the magnetosome. Iron transport system supports the biogenesis of magnetite. Although iron is an essential trace element for many metabolic pathways of the body, increase or decrease in iron will cause many diseases. Mice were infected by MSR-1 to study survival of bacteria in mice when injected by different routes. The aim of this study was to investigate whether bacterial magnetite formation could take up Fe(2+) ions from the blood an animal model.

MATERIAL AND METHODS

In this study, MSR-1 at a dose lower than LD(50) in 200 µl volume of PBS buffer was injected as intravascular (i.v), peritoneal (i.p) and subcutaneous (s.c) in mice. Number of viable bacterial was determined in organs such as liver, spleen and lymph node by measuring colony-forming unit (CFU). Moreover, serum iron level was evaluated by using commercial kits.

RESULTS AND CONCLUSION

According to CFU measurements, after 96 hours, mice can clear MSR-1 from their body with different routes of injection. We have also shown that MSR-1 bacteria can affect the blood iron level in mice. The serum iron level decreased from control level in the first 24 h after i.v injection (P< 0.05). Our research on optimizing the biological magnetic system is still continuing.