scholarly journals Bubble Properties in Bubbling and Turbulent Fluidized Beds for Particles of Geldart’s Group B

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1098
Author(s):  
Tom Wytrwat ◽  
Mahdi Yazdanpanah ◽  
Stefan Heinrich
Keyword(s):  
Fluidized Beds ◽  
Pressure Fluctuations ◽  
Bubble Velocity ◽  
Turbulent Regime ◽  
Bubble Behavior ◽  
Low Velocity ◽  
Group B ◽  
Superficial Gas Velocity ◽  
Bubble Properties

Predicting bubble properties in fluidized beds is of high interest for reactor design and modeling. While bubble sizes and velocities for low velocity bubbling fluidized beds have been examined in several studies, there have been only few studies about bubble behavior at superficial gas velocities up into the turbulent regime. For this reason, we performed a thorough investigation of the size, shape and velocity of bubbles at superficial gas velocities ranging from 0.18 m/s up to 1.6 m/s. Capacitance probes were used for the determination of the bubble properties in three different fluidized bed facilities sized of 0.1 m, 0.4 m and 1 m in diameter. Particles belonging to Geldart’s group B (Sauter mean diameter: 188 µm, solid density: ρs = 2600 kg/m3) were used. Correlations for the determination of bubble phase holdup, vertical bubble length and bubble velocity are introduced in this work. The shape of bubbles was found to depend on superficial gas velocity. This implies that at large superficial gas velocities the horizontal size of a bubble must be much smaller in comparison to its vertical size. This leads to a decrease of pressure fluctuations, which is observed in the literature as a characteristic of transitioning into a turbulent regime.

scholarly journals Hematological Features in Sheep with IgG and IgM Antibodies against Borrelia burgdorferi sensu lato

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 164
Author(s):  
Labrini V. Athanasiou ◽  
Victoria M. Spanou ◽  
Eleni G. Katsogiannou ◽  
Panagiotis D. Katsoulos
Keyword(s):  
Borrelia Burgdorferi ◽  
Rural Areas ◽  
Blood Analysis ◽  
Borrelia Burgdorferi Sensu Lato ◽  
Igm Antibodies ◽  
Group A ◽  
Group B ◽  
Group D ◽  
Immunofluorescence Antibody

Exposure of sheep to Borreliaburgdorferi sensulato (s.I.) complex, the causative agent of Lyme borreliosis (LB), has been reported in tick-abundant areas worldwide, while no data have been reported in Greece. The aim of the study was to identify the hematological alterations in sheep with seropositivity against Borrelia burgdorferi (s.I.). Blood samples were obtained from 318 tick infested sheep for blood analysis and serological determination of IgG and IgM antibodies against B. burgdorferi by indirect immunofluorescence antibody (IFA) assay after exclusion of endo-ectoparasites and other tick-borne infections. A total number of 162 sheep met the inclusion criteria, allocated in four groups based on the presence or absence of IgG and/or IgM; sheep found negative for IgM and IgG (Group A), positive for IgM (Group B), positive for both IgM and IgG (Group C) and positive for IgG (Group D). Anemia, thrombocytopenia and normal or decreased leukocyte count, mainly due to lymphopenia were the main hematological features observed in seropositive sheep. The presence of these features raises the suspicion of Borrelia infection in tick infested sheep. The seropositivity of 23.58% in sheep raises concerns of Borrelia circulation, especially in rural areas and potential risk of transmission to humans.

Velocity Profiles of Liquid Flow Through Circular Tubes and How They Affect Flow Measurement

1991 ◽  
Vol 113 (3) ◽  
pp. 206-210 ◽  
Author(s):  
D. Yogi Goswami
Keyword(s):  
Transition Region ◽  
Laser Doppler Velocimetry ◽  
Flow Measurement ◽  
Velocity Profiles ◽  
Turbulent Regime ◽  
Flow Meters ◽  
Circular Tubes ◽  
Flow Through ◽  
Hydrogen Bubble Technique

This paper analyzes velocity profiles for flow through circular tubes in laminar, turbulent, and transition region flows and how they affect measurement by flow-meters. Experimental measurements of velocity profiles across the cross-section of straight circular tubes were made using laser doppler velocimetry. In addition, flow visualization was done using the hydrogen bubble technique. Velocity profiles in the laminar and the turbulent flow are quite predictable which allow the determination of meter factors for accurate flow measurement. However, the profiles can not be predicted at all in the transition region. Therefore, for the accuracy of the flowmeter, it must be ensured that the flow is completely in the laminar regime or completely in the turbulent regime. In the laminar flow a bend, even at a large distance, affects the meter factor. The paper also discusses some strategies to restructure the flow to avoid the transition region.

scholarly journals Clinical Efficacy Of Ceftriaxone Versus Ciprofloxacin In Paediatric Enteric Fever

2018 ◽  
Vol 08 (02) ◽  
pp. 67-71
Author(s):  
Anila Farhat ◽  
Asma Shaukat ◽  
Tariq Mahmood Khan
Keyword(s):  
Enteric Fever ◽  
Research Study ◽  
Controlled Trial ◽  
Clinical Effectiveness ◽  
Randomized Controlled ◽  
Group A ◽  
The Mean ◽  
Group B ◽  
Objective Determination

Objective: Determination of the clinical effectiveness of ciprofloxacin versus ceftriaxone in children with enteric fever on the basis of defervescence within 72 hours of commencement of treatment. Duration and Place of Study: This randomized controlled trial was carried out from 15th May to 15th November 2017 in pediatrics units of Benazir Bhutto Shaheed Teaching Hospital Abbottabad and Jinnah International Hospital Abbottabad. Methodology: 90 children with uncomplicated enteric fever were admitted and divided randomly into two groups, Group A was administered I/V Ceftriaxone 75mg/kg OD and Group B was given I/V Ciprofloxacin 10mg/kg BD for seven days. Response to drug was taken as defervescence within 72 hours while continued fever after 72 hours was taken as no response. The data was analyzed by using SPSS Version 21.00. Results: In our research study 53(58.9%) children were male and 37(41.1%) patients were female. The mean age was 8.43±3.17 years encompassing 4 to 14 years, mean weight of the patients in kg was 29.54±10.8 kg. Efficacy of ceftriaxone group was 93.3% while in ciprofloxacin group 62.2% patients became afebrile in 72 hours. The proportion of achieving defervescence within 72 hours was higher with ceftriaxone than with ciprofloxacin Conclusion: Ceftriaxone is more efficacious in terms of achieving defervescence than ciprofloxacin in children having enteric fever.

scholarly journals STUDY OF PROCESSES OF PRESSURE AND IMPULSE FREQUENCY INFLUENCE ON PENETRATION OF LIQUIDS IN THE SAND SAMPLES

2016 ◽  
pp. 120-125
Author(s):  
M. Ya. Habibullin ◽  
R. R. Shangareyev
Keyword(s):  
Experimental Data ◽  
Oil Recovery ◽  
Pressure Fluctuations ◽  
Experimental Studies ◽  
Regression Equations ◽  
Linear Variation ◽  
Frequency Range ◽  
Impulse Frequency ◽  
Overburden Pressure

The article deals with the issues related to the hydrocarbon reservoirs oil recovery enhancement. It describes the bench laboratory experimental studies. The results obtained during determination of fluid leakage through the rock samples and the amount of absorption of pressure fluctuations at various regime parameters are presented. Using the experimental data the regression analysis was performed on the basis of which the qualitative correlations between factorial and resultant features were identified. Using the regression equations the graphic relations were constructed. It was found that with increasing the oscillation frequency of the fluid the amount of fluid passing through the sample of porous medium increased, with the highest value of q reached at the frequency range of 600 ... 1000 Hz. With increase in the oscillations penetration depth the absorption of the amplitude of the pressure fluctuations corresponds to the linear decrease, and with the overburden pressure increase the linear variation of absorption is distorted.

scholarly journals The Role of Pathological Method and Clearance Definition for the Evaluation of Margin Status after Pancreatoduodenectomy for Periampullary Cancer. Results of a Multicenter Prospective Randomized Trial

Cancers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 2097
Author(s):  
Gennaro Nappo ◽  
Domenico Borzomati ◽  
Alessandro Zerbi ◽  
Paola Spaggiari ◽  
Ugo Boggi ◽  
...  
Keyword(s):  
Prognostic Factor ◽  
Randomized Study ◽  
Periampullary Cancer ◽  
Significant Prognostic Factor ◽  
Prognostic Role ◽  
R1 Resection ◽  
Group A ◽  
Group B

Background: There is extreme heterogeneity in the available literature on the determination of R1 resection rate after pancreatoduodenectomy (PD); consequently, its prognostic role is still debated. The aims of this multicenter randomized study were to evaluate the effect of sampling and clearance definition in determining R1 rate after PD for periampullary cancer and to assess the prognostic role of R1 resection. Methods: PD specimens were randomized to Leeds Pathology Protocol (LEEPP) (group A) or the conventional method adopted before the study (group B). R1 rate was determined by adopting 0- and 1-mm clearance; the association between R1, local recurrence (LR) and overall survival (OS) was also evaluated. Results. One-hundred-sixty-eight PD specimens were included. With 0 mm clearance, R1 rate was 26.2% and 20.2% for groups A and B, respectively; with 1 mm, R1 rate was 60.7% and 57.1%, respectively (p > 0.05). Only in group A was R1 found to be a significant prognostic factor: at 0 mm, median OS was 36 and 20 months for R0 and R1, respectively, while at 1 mm, median OS was not reached and 30 months. At multivariate analysis, R1 resection was found to be a significant prognostic factor independent of clearance definition only in the case of the adoption of LEEPP. Conclusions. The 1 mm clearance is the most effective factor in determining the R1 rate after PD. However, the pathological method is crucial to accurately evaluate its prognostic role: only R1 resections obtained with the adoption of LEEPP seem to significantly affect prognosis.

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