Continuous removal of glycerol from frozen-thawed red blood cells in a microfluidic membrane device

Cryopreservation of human red blood cells (RBCs) in the presence of 40% glycerol allows a shelf-life of 10 years, as opposed to only 6 weeks for refrigerated RBCs. Nonetheless, cryopreserved blood is rarely used in clinical therapy, in part because of the requirement for a time-consuming (∼1 h) post-thaw wash process to remove glycerol before the product can be used for transfusion. The current deglycerolization process involves a series of saline washes in an automated centrifuge, which gradually removes glycerol from the cells in order to prevent osmotic damage. We recently demonstrated that glycerol can be extracted in as little as 3 min without excessive osmotic damage if the composition of the extracellular solution is precisely controlled. Here, we explore the potential for carrying out rapid glycerol extraction using a membrane-based microfluidic device, with the ultimate goal of enabling inline washing of cryopreserved blood. To assist in experimental design and device optimization, we developed a mass transfer model that allows prediction of glycerol removal, as well as the resulting cell volume changes. Experimental measurements of solution composition and hemolysis at the device outlet are in reasonable agreement with model predictions, and our results demonstrate that it is possible to reduce the glycerol concentration by more than 50% in a single device without excessive hemolysis. Based on these promising results, we present a design for a multistage process that is predicted to safely remove glycerol from cryopreserved blood in less than 3 min.     

Capillary flow in sacrificially etched nanochannels

Planar nanochannels are fabricated using sacrificial etching technology with sacrificial cores consisting of aluminum, chromium, and germanium, with heights ranging from 18 to 98 nm. Transient filling via capillary action is compared against the Washburn equation [E. W. Washburn, Phys. Rev. 17, 273 (1921)], showing experimental filling speeds significantly lower than classical continuum theory predicts. Departure from theory is expressed in terms of a varying dynamic contact angle, reaching values as high as 83° in channels with heights of 18 nm. The dynamic contact angle varies significantly from the macroscopic contact angle and increases with decreasing channel dimensions.     

A Pan‐European Credit Accumulation Framework – Dream or Disaster?

This article seeks to examine credit accumulation and transfer from a European perspective, which involves four interlocking elements. Firstly, it analyses the current potential for rapid change within European education systems. Secondly, it considers the current nature, strengths and limitations of the European Credit Transfer System (ECTS) inspired by the European Commission. Thirdly, it seeks to identify the technical obstacles that need to be overcome to enable ECTS to evolve into something much more powerful, namely, a pan-European credit accumulation and transfer framework. Finally, it considers whether such a development is a dream or a disaster and if one or the other, then for whom.     

Regularized Structural Equation Modeling

A new method is proposed that extends the use of regularization in both lasso and ridge regression to structural equation models. The method is termed regularized structural equation modeling (RegSEM). RegSEM penalizes specific parameters in structural equation models, with the goal of creating easier to understand and simpler models. Although regularization has gained wide adoption in regression, very little has transferred to models with latent variables. By adding penalties to specific parameters in a structural equation model, researchers have a high level of flexibility in reducing model complexity, overcoming poor fitting models, and the creation of models that are more likely to generalize to new samples. The proposed method was evaluated through a simulation study, two illustrative examples involving a measurement model, and one empirical example involving the structural part of the model to demonstrate RegSEM’s utility.     

Auditory Context and Memory Retrieval in Young Infants

Three-month-old infants were trained to move an overhead crib mobile while 1 of 2 musical selections was played. Retention was assessed 1 or 7 days later in the presence of either the same music or a different musical selection. in Experiment 1, the musical selections were very different (classical versus jazz); in Experiment 2, they were much more similar (two classical pieces). Infants in both experiments displayed 1 day retention regardless of wich music was played during the retention test. At 7 days, retention was seen only when the music played during the retention test matched the training music. These data are consistent with similar findings showing that 3-month-old infants'memory is disrupted at long retention intervals when the context present during retention testing does not match the learning context. As the infant's memory wanes, context appears to function as a necessary cue for the retrieval of acquired expectancies.