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1. Continuous CTC separation through a DEP ‐based contraction–expansion inertial microfluidic channel

   https://doi.org/10.1002/btpr.3341  

   Islam, Md_Sadiqul; Chen, Xiaolin (March 2023, Biotechnology Progress)

   Abstract The efficient isolation of viable and intact circulating tumor cells (CTCs) from blood is critical for the genetic analysis of cancer cells, prediction of cancer progression, development of drugs, and evaluation of therapeutic treatments. While conventional cell separation devices utilize the size difference between CTCs and other blood cells, they fail to separate CTCs from white blood cells (WBCs) due to significant size overlap. To overcome this issue, we present a novel approach that combines curved contraction–expansion (CE) channels with dielectrophoresis (DEP) and inertial microfluidics to isolate CTCs from WBCs regardless of size overlap. This label‐free and continuous separation method utilizes dielectric properties and size variation of cells for the separation of CTCs from WBCs. The results demonstrate that the proposed hybrid microfluidic channel can effectively isolate A549 CTCs from WBCs regardless of their size with a throughput of 300 μL/min, achieving a high separation distance of 233.4 μm at an applied voltage of 50 V_p–p. The proposed method allows for the modification of cell migration characteristics by controlling the number of CE sections of the channel, applied voltage, applied frequency, and flow rate. With its unique features of a single‐stage separation, simple design, and tunability, the proposed method provides a promising alternative to the existing label‐free cell separation techniques and may have a wide range of applications in biomedicine. 

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2. Shear‐induced migration and axial development of particles in channel flows of non‐Brownian suspensions

   https://doi.org/10.1002/aic.17100  

   Rashedi, Ahmadreza; Sarabian, Mohammad; Firouznia, Mohammadhossein; Roberts, Dallas; Ovarlez, Guillaume; Hormozi, Sarah (October 2020, AIChE Journal)

   Abstract We present an experimental study on the shear‐induced migration and axial development of particles in the channel flows of non‐Brownian suspensions. The suspending fluid is Newtonian. We investigate fracturing flows with a Hele‐Shaw type scaling through building a unique channel setup and an advanced optical system. The local particle concentration profiles are measured via the refractive‐index matching technique for a wide range of bulk volume fraction, that is,. Simultaneously, the particle image velocimetry is performed to determine the velocity profile of the particle phase. We compare our experimental results with the available two‐phase continuum frameworks and show discrepancies and similarities in the fully developed and axial development of the solid volume fraction profiles. We discuss directions in which the continuum frameworks require improvements. 

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3. VDAC Solvation Free Energy Calculation by a Nonuniform Size Modified Poisson–Boltzmann Ion Channel Model

   https://doi.org/10.1002/jcc.70003  

   Jemison, Liam; Stahl, Matthew; Dash, Ranjan_K; Xie, Dexuan (December 2024, Journal of Computational Chemistry)

   ABSTRACT Voltage‐dependent anion channel (VDAC) is the primary conduit for regulated passage of ions and metabolites into and out of a mitochondrion. Calculating the solvation free energy for VDAC is crucial for understanding its stability, function, and interactions within the cellular environment. In this article, numerical schemes for computing the total solvation free energy for VDAC—comprising electrostatic, ideal gas, and excess free energies plus the nonpolar energy—are developed based on a nonuniform size modified Poisson–Boltzmann ion channel (nuSMPBIC) finite element solver along with tetrahedral meshes for VDAC proteins. The current mesh generation package is also updated to improve mesh quality and accelerate mesh generation. A VDAC Solvation Free Energy Calculation (VSFEC) package is then created by integrating these schemes with the updated mesh package, the nuSMPBIC finite element package, the PDB2PQR package, and the OPM database, as well as one uniform SMPBIC finite element package and one Poisson–Boltzmann ion channel (PBIC) finite element package. With the VSFEC package, many numerical experiments are made using six VDAC proteins, eight ionic solutions containing up to four ionic species, including ATP⁴⁻and Ca²⁺, two reference states, different boundary values, and different permittivity constants. The test results underscore the importance of considering nonuniform ionic size effects to explore the varying patterns of the total solvation free energy, and demonstrate the high performance of the VSFEC package for VDAC solvation free energy calculation. 

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4. HAIRY MERISTEM proteins regulate the WUSCHEL protein levels in mediating CLAVATA3 expression

   https://doi.org/10.1111/ppl.14505  

   Rodriguez, Kevin; Kao, Lloyd; Cerbantez‐Bueno, Vincent_E; Delgadillo, Christian; Nguyen, Dorothy; Ullah, Samin; Delgadillo, Cameron; Reddy, G_Venugopala (September 2024, Physiologia Plantarum)

   Abstract The precise regulation of stem cells in the shoot apical meristems (SAMs) involves the function of the homeodomain transcription factor (TF)‐WUSCHEL (WUS). WUS has been shown to move from the site of production‐the rib‐meristem (RM), into overlaying cells of the central zone (CZ), where it specifies stem cells and also regulates the transcription ofCLAVATA3 (CLV3). The secreted signalling peptide CLV3 activates a receptor kinase signalling that restrictsWUStranscription and also regulates the nuclear gradient of WUS by offsetting nuclear export. WUS has been shown to regulate bothCLV3levels and spatial activation, restricting its expression to a few cells in the CZ. The HAIRY MERISTEM (HAM), a GRASS‐domain class of TFs expressed in the RM, has been shown to physically interact with WUS and regulateCLV3expression. However, the mechanisms by which this interaction regulatesCLV3expression non‐cell autonomously remain unclear. Here, we show that HAM function is required for regulating the WUS protein stability, and theCLV3expression responds to altered WUS protein levels inhammutants. Thus, HAM proteins non‐cell autonomously regulatesCLV3expression. 

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5. Children's engineering identities‐in‐practice : An exploration of child–adult interactions in an out‐of‐school context

   https://doi.org/10.1002/jee.20553  

   Simpson, Amber; Knox, Peter N.; Yang, Jing (August 2023, Journal of Engineering Education)

   Abstract BackgroundResearch points to family talk and interactions involving STEM concepts as one of the most influential informal learning experiences that shape an individual's STEM identity development and encourage their pursuit of a STEM career. However, a recent literature review uncovers limited research regarding the development of engineering identity in young children. PurposeThe purpose of this study was to add to this scant literature by exploring how children position themselves as engineers and how children are positioned as engineers through interactions with parents and other adults within a program focused on family engagement within an engineering design process. MethodsThis study includes two parent–child dyads. We collected and analyzed approximately 19.5 h of video data of the two child–parent dyads interacting with one another throughout an engineering design process as part of an out‐of‐school program. ResultsResults highlight three ways in which the two children enacted various engineering identities through their positioning, negotiation, and acceptance and/or rejection of positionalities as they engaged in an engineering design process with a parent. These identity enactments included (a) possessing knowledge and authority to make decisions regarding the development of their self‐identified engineering problem and prototype; (b) questioning and challenging adult ideas, solutions, and construction of prototypes; and (c) documenting and communicating their thinking regarding the engineering design through sketches and notes. ConclusionsThe significance of this study lies in its potential to change the landscape of those who pursue an engineering career and to contribute to the limited research and ongoing conversations about how to foster environments that support families in creative and collaborative learning specific to the engineering discipline. 

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