Effect of Liquid- and Gas-Mixing on the Rate of Mass Transfer between Two Phases in Crosscurrent Flow

The theoretical correlations have been derived by the authors for the concentration gradients in the froth layer on a sieve or bubble-cap plate, based on the assumption that the flow velocities of the gas and liquid in each direction are constant throughout the froth layer. The degree of liquid- and gas-mixing was experessed by the backmixing diffusion. Point efficiency varies with change in the number of transfer units and with the degree of gas-mixing. The liquid-mixing has no effect on the point efficiency. Plate efficiency is affected by both the liquid- and gas-mixing. The effect of the liquid-mixing is more marked than that of gas-mixing

Micro-Mixing in a Continuous Flow Reactor : Coalescence and Redispersion Models

For the fluid mixing which occurs in a continuous flow reactor, two different mechanisms must be considered. The one is macro-mixing resulting from the difference in residence time of outflowing fluid and the other is micro-mixing caused by the mass exchange between fluid elements. In this paper new models for the micro-mixing are presented as follows : The incoming fluid is broken up into discrete fragments of equal volume which are small enough compared to the reactor size. A fragment of fluid comes into contact and coalescence with another l/tc times per unit time on an average, and is immediately rebroken into two fragments of equal volume. The concentration in the fragments becomes uniform at the instant of coalescence. From the above assumptions, the basic design equations are derived, and for the ideal perfect macro-mixing reactor, the effect of micro-mixing on the conversion of zero, first, and second order reactions is considered. In the case of first order reactions the micro-mixing has no effect on the conversion. In the case of reactions of zero and second order, the conversion is caluculated by equations (24), (36) and (30), (38), respectively. And the validity of these equations for second order reaction is discussed using a reaction which takes place in liquid droplets dispersed in an inert phase

Policy Issues in Implementing Smart Cards in Urban Public Transit Systems

Many public transportation institutions have been discarding their magnetic strip payment cards or traditional cash-based fee collection systems in favor of automated fare collection systems with smart card technology. Smart cards look like traditional credit cards or ID cards; however, using RFID technology, they allow for contactless payment and identification. Smart cards are becoming increasingly popular among transit agencies primarily because they are convenient for customers, reduce administrative costs for transit agencies, and have the potential of improving the performance of complex transit systems overall. The increased availability and affordability of contactless cards has also contributed to this trend in adoption

Advantages of acute brain slices prepared at physiological temperature in the characterization of synaptic functions

Acute brain slice preparation is a powerful experimental model for investigating the characteristics of synaptic function in the brain. Although brain tissue is usually cut at ice-cold temperature (CT) to facilitate slicing and avoid neuronal damage, exposure to CT causes molecular and architectural changes of synapses. To address these issues, we investigated ultrastructural and electrophysiological features of synapses in mouse acute cerebellar slices prepared at ice-cold and physiological temperature (PT). In the slices prepared at CT, we found significant spine loss and reconstruction, synaptic vesicle rearrangement and decrease in synaptic proteins, all of which were not detected in slices prepared at PT. Consistent with these structural findings, slices prepared at PT showed higher release probability. Furthermore, preparation at PT allows electrophysiological recording immediately after slicing resulting in higher detectability of long-term depression (LTD) after motor learning compared with that at CT. These results indicate substantial advantages of the slice preparation at PT for investigating synaptic functions in different physiological conditions

Efficacy of human resource development program for young industry personnel who will be involved in future medical device development

Background: Training next-generation personnel from small/medium enterprises (SMEs) is an urgent issue in promoting medical device research and development (R&D). Since 2014 we have engaged in governmentally funded human resource development program for medical/non-medical SMEs, and have assessed its effectiveness by analyzing self-evaluation of achievement level (SEAL) data obtained before and after the training course. Methods: Human resource development experts interviewed 34 key opinion leaders with deep knowledge of medical device R&D from industry, government, and academia. The skills required for R&D personnel were written down, and a set of skills was created by making a greatest common measure in the list of common elements among them. Using that skill sets, skill evaluations were conducted on trainees at “Osaka University Training Course,” twice before participation and after completion of the entire program using SEAL assessment. Results: There were 97 men and 25 women, with one-third in the’30 s. Among them, 61 participants (50%) were from R&D divisions, and 32 (26%) were from business/sales divisions. 94 (77%) were from medical SMEs, and 28 (23%) were from non-medical SMEs (new entry). After completing the training course, significant growth was observed in every item of both Soft and Hard skill sets. Especially in new entry SME members, a striking improvement was observed in practical medical knowledge to enhance communication with medical doctors (p < 0.0001). Conclusion: Our training course, though 7-day-short in total, showed that both Soft and Hard skills could be improved in young medical/non-medical SME members. Further assessment is needed to establish the necessary skill sets for our future partners from industries, to foster the creation of innovative medical devices through med-tech collaboration.The version of record of this article, first published in Surgical Endoscopy, is available online at Publisher’s website: https://doi.org/10.1007/s00464-023-10474-

Study on the relationship between rainfall, topography and landslide volume in the recent debris flow disasters in Hiroshima, Japan

Three types of sediment volume estimation equations were developed by analyzing the relationship between rainfall, topography (e.g. slope gradient, relative height) and the volume of collapsed sediment in 1 km grid for heavy rainfall events (2014 and 2018 events) in Hiroshima Prefecture where intensive slope failures and debris flows occurred. All three equations showed a tendency for the volume of collapsed sediment per unit area to increase with increasing rainfall. However, some equations showed the rate of increase tends to gradually plateau

BRST Analysis of Physical States in Two-Dimensional Black Hole

We study the BRST cohomology for $SL(2,R)/U(1)$ coset model, which describes an exact string black hole solution. It is shown that the physical spectrum could contain not only the extra discrete states corresponding to those in $c=1$ two-dimensional gravity but also many additional new states with ghost number $N_{FP}= -1 \sim 2$. We also discuss characters for nonunitary representations and the relation of our results to other approaches.Comment: 44 pages, OS-GE 28-93, OU-HET 17