Gas Holdup in a Trayed Cold-Flow Bubble Column

An Experimental Study Was Performed to Investigate the Effect of Sieve Trays on the Time-Averaged Gas Holdup Profiles and the overall Gas Holdup in a Cold-Flow Bubble Column that Was Scaled-Down from a Commercial Unit. Γ-Ray Computed Tomography (CT) Was Used to Scan the Column at Several Axial Locations in the Presence and Absence of Trays from Which the Local Variation of the Gas Holdup Was Extracted. the overall Gas Holdup Was Also Determined using the Same Configuration by Comparing the Expanded and Static Liquid Heights. Air and Water Were Used as the Gas-Liquid System. the Superficial Gas and Liquid Velocities Were Selected to Span the Range of the Commercial System using Gas Spargers Having Multiple Lateral Distributors that Were Also Scaled-Down from the Commercial Design. to Investigate the Impact of Sparger Hole Density on the Local and overall Gas Holdup, Two Difference Sparger Designs Were Used in Which the Hole Density Per Lateral Was Varied. the Gas Hole Velocity Was Maintained Constant at Ca. 245 M/s, Which Approached that Used in the Commercial Reactor. It is Shown that the Local Gas Holdup Determined by CT is Generally Higher in the Tray Down Comer Region and Exhibits an Asymmetric Pattern When Trays Are Present. the Use of Increased Sparger Hole Density at a Constant Gas Superficial Velocity Leads to Steeper Gradient in the Gas Holdup Near the Column Centerline and a Higher overall Gas Holdup. These Findings Suggest that the Performance of Bubble Column Reactors for Various Applications is Sensitive to Both Sparger and Tray Design. © 2001 Elsevier Science Ltd. All Rights Reserved

Progress in Micro Joule-Thomson Cooling at Twente University

At the University of Twente, research on the development of a sorption-based micro cooler is in progress. Because of the absence of moving parts, such a cooler is virtually vibration free and highly durable, which potentially results in a long lifetime. A miniature cryogenic cooler with these properties would be appealing in a wide variety of applications including the cooling of vibration-sensitive detectors in space missions, low-noise amplifiers and semi- and superconducting circuitry. The objective of the present project is to scale down a Joule-Thomson (JT) cold stage to a total volume of a few hundredths of a cm3. This size reduction introduces many problems. The proposed cold stage volume results in a restriction cross-sectional area of about a thousandth of a mm2 which may cause clogging problems. Flow channels with a cross-sectional area of a few hundredths of a mm2 will produce high pressure drops influencing the JT cycle. Furthermore, the micro channels must be capable of withstanding high pressures and maintaining a large temperature gradient over a relatively short length. The project aim is to develop a reliable micro JT cold stage that is fabricated out of one material with a relatively simple and reproducible fabrication method. The length of the cold stage is calculated at about 20 mm with a width of 1.7 mm and height of about 0.3 mm. The mass flow is in the order of one mg per second to create a net cooling power of 10 mW at 96 K. The final objective of the project is to integrate the cold stage, vacuum chamber and device into one compact design. This paper discusses possible solutions to the problems mentioned and presents a concept design of such a miniature JT cold stage

Desflurane consumption during automated closed-circuit delivery is higher than when a conventional anesthesia machine is used with a simple vaporizer-O2-N2O fresh gas flow sequence

The Zeus® (Dräger, Lübeck, Germany), an automated closed-circuit anesthesia machine, uses high fresh gas flows (FGF) to wash-in the circuit and the lungs, and intermittently flushes the system to remove unwanted N₂. We hypothesized this could increase desflurane consumption to such an extent that agent consumption might become higher than with a conventional anesthesia machine (Anesthesia Delivery Unit [ADU®], GE, Helsinki, Finland) used with a previously derived desflurane-O₂-N₂O administration schedule that allows early FGF reduction.Journal ArticleSCOPUS: ar.jinfo:eu-repo/semantics/publishe

The Distribution of Genomic Variations in Human iPSCs Is Related to Replication-Timing Reorganization during Reprogramming

Cell fate change involves significant genome reorganization, including change in replication timing, but how these changes are related to genetic variation has not been examined. To study how change in replication timing that occurs during reprogramming impacts the copy number variation (CNV) landscape, we generated genome-wide replication timing profiles of induced pluripotent stem cells (iPSCs) and their parental fibroblasts. A significant portion of the genome changes replication timing as a result of reprogramming, indicative of overall genome reorganization. We found that early and late replicating domains in iPSCs are differentially affected by copy number gains and losses, and that in particular CNV gains accumulate in regions of the genome that change to earlier replication during the reprogramming process. This differential relationship was present irrespective of reprogramming method. Overall, our findings reveal a functional association between reorganization of replication timing and the CNV landscape that emerges during reprogramming

Hosting an Educational Careers Day Within the Virtual Paradigm: The Neurology and Neurosurgery Interest Group Experience.

INTRODUCTION:  To explore our experience of hosting the 10th Annual Neurology and Neurosurgery Interest Group-Society of British Neurological Surgeons (NANSIG-SBNS) Neurosurgery Careers Day, held virtually for the first time. METHODS:  Reflective feedback and review of an international, virtual neurosurgery careers day. The authors reflect on the logistics of organizing the event, and the pre- and post-event feedback provided by delegates. Recommendations have been made on how to successfully host a virtual event. The key themes that permeated the event have been outlined and discussed in the context of the feedback received. RESULTS:  The event was attended by 231 delegates from 20 countries worldwide. Knowledge of neurosurgery as a career and the application process increased after attending the careers day (4.27/5 to 4.51/5, p=0.003 and 3.12/5 to 4.31/5, p<0.001 respectively). The key themes identified from the event include attendance, networking, and education. Qualitative feedback was positive and indicated a positive perception of the careers day. CONCLUSIONS:  The future of educational events is unclear, and a hybrid approach is recommended to retain the benefits of the online space when in-person events eventually return

Hosting an Educational Careers Day Within the Virtual Paradigm: The Neurology and Neurosurgery Interest Group Experience.

INTRODUCTION:  To explore our experience of hosting the 10th Annual Neurology and Neurosurgery Interest Group-Society of British Neurological Surgeons (NANSIG-SBNS) Neurosurgery Careers Day, held virtually for the first time. METHODS:  Reflective feedback and review of an international, virtual neurosurgery careers day. The authors reflect on the logistics of organizing the event, and the pre- and post-event feedback provided by delegates. Recommendations have been made on how to successfully host a virtual event. The key themes that permeated the event have been outlined and discussed in the context of the feedback received. RESULTS:  The event was attended by 231 delegates from 20 countries worldwide. Knowledge of neurosurgery as a career and the application process increased after attending the careers day (4.27/5 to 4.51/5, p=0.003 and 3.12/5 to 4.31/5, p<0.001 respectively). The key themes identified from the event include attendance, networking, and education. Qualitative feedback was positive and indicated a positive perception of the careers day. CONCLUSIONS:  The future of educational events is unclear, and a hybrid approach is recommended to retain the benefits of the online space when in-person events eventually return