Inducing Mild Traumatic Brain Injury in C. elegans via Cavitation-Free Surface Acoustic Wave-Driven Ultrasonic Irradiation.

Mild traumatic brain injury is an all-too-common outcome from modern warfare and sport, and lacks a reproducible model for assessment of potential treatments and protection against it. Here we consider the use of surface acoustic wave (SAW) irradiation of C. elegans worms-without cavitation-as a potential, ethically reasonable animal-on-a-chip model for inducing traumatic brain injury in an animal, producing significant effects on memory and learning that could prove useful in a model that progress from youth to old age in but a few weeks. We show a significant effect by SAW on the ability of worms to learn post-exposure through associative learning chemotaxis. At higher SAW intensity, we find immediate, thorough, but temporary paralysis of the worms. We further explore the importance of homogeneous exposure of the worms to the SAW-driven ultrasound, an aspect poorly controlled in past efforts, if at all, and demonstrate the absence of cavitation through a change in fluids from a standard media for the worms to the exceedingly viscous polyvinyl alcohol. Likewise, we demonstrate that acoustic streaming, when present, is not directly responsible for paralysis nor learning disabilities induced in the worm, but is beneficial at low amplitudes to ensuring homogeneous ultrasound exposure

pH dependent isotropic to nematic phase transitions in graphene oxide dispersions reveal droplet liquid crystalline phases

Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Royal Society of Chemistry for personal use, not for redistribution. The definitive version was published in Chemical Communications 50 (2014): 6668-6671, doi:10.1039/C4CC00970C.Size fractionation, amplified by the surface charge density of graphene oxide (GO) sheets, broadens the pH dependent isotropic (I) to nematic (N) phase transition in aqueous dispersions of graphene oxide (GO). In this biphasic region, a highly organized droplet nematic phase of uniform size (20 ± 2.8 μm diameter) with an isotropic interior is observed.Supports from the Australian Research Council (LP110100612 to MM), National Institute of Biomedical Imaging and Bioengineering (R01EB002045 to RO) and HFSP fellowship (to SM) are acknowledged.2015-05-0

A Novel On‐Chip Method for Differential Extraction of Sperm in Forensic Cases

One out of every six American women has been the victim of a sexual assault in their lifetime. However, the DNA casework backlog continues to increase outpacing the nation\u27s capacity since DNA evidence processing in sexual assault casework remains a bottleneck due to laborious and time‐consuming differential extraction of victim\u27s and perpetrator\u27s cells. Additionally, a significant amount (60–90%) of male DNA evidence may be lost with existing procedures. Here, a microfluidic method is developed that selectively captures sperm using a unique oligosaccharide sequence (Sialyl‐LewisX), a major carbohydrate ligand for sperm‐egg binding. This method is validated with forensic mock samples dating back to 2003, resulting in 70–92% sperm capture efficiency and a 60–92% reduction in epithelial fraction. Captured sperm are then lysed on‐chip and sperm DNA is isolated. This method reduces assay‐time from 8 h to 80 min, providing an inexpensive alternative to current differential extraction techniques, accelerating identification of suspects and advancing public safety

AN APPROXIMATE SOLUTION FOR DIFFERENT TYPES OF WAVE PROBLEMS

Abstract: In this article, He's variational iteration method (VIM) is implemented to solve the non-homogeneous dissipative wave, Helmholtz and some nonlinear fifth-order Korteweg-de Vries (FKdV) partial differential equations with specified initial conditions. The initial approximations can be freely chosen with possible unknown constants which can be determined by imposing the boundary or initial conditions after few iterations. Comparison of the results with those obtained by exact solution and Adomian's decomposition method reveals that VIM is very effective, convenient and quite accurate to both linear and nonlinear problems. It is predicted that VIM can be widely applied in engineering. Key words: Variational iteration method, Helmholtz equation, FKdV equation, nonlinear partial differential equations DALGA PROBLEMLERİNİN FARKLI TİPLERİ İÇİN BİR YAKLAŞIK ÇÖZÜM Özet: Bu makalede, He'nin varyasyonel iterasyon yöntemi (VIM), belli başlangıç koşulları ile homojen olmayan dissipative dalga, Helmholtz ve bazı lineer olmayan beşinci mertebeden Korteweg-de Vries (FKdV) kısmi diferansiyel denklemlerini çözmek için uygulanmıştır. Başlangıç yaklaşımları, birkaç iterasyon sonra başlangıç ve sınır koşullarının uygulanmasıyla belirlenebilen mümkün bilinmeyen sabitler ile keyfi olarak seçilebilir. Analitik çözüm ve Adomian'ın ayrıştırma yöntemi ile elde edilen sonuçların karşılaştırılması, VIM'in çok etkili, uygun ve hem lineer hem de lineer olmayan problemler için oldukça hatasız olduğunu ortaya koymaktadır. VIM'in mühendislikte yaygın olarak uygulanabildiği tahmin edilmektedir. Anahtar kelimeler: Varyasyonel iterasyon yöntemi, Helmholtz denklemi, FKdV denklemi, lineer olmayan kısmi diferansiyel denklemle

Continuous Submicron Particle Separation Via Vortex-Enhanced Ionic Concentration Polarization: A Numerical Investigation

Separation and isolation of suspended submicron particles is fundamental to a wide range of applications, including desalination, chemical processing, and medical diagnostics. Ion concentration polarization (ICP), an electrokinetic phenomenon in micro-nano interfaces, has gained attention due to its unique ability to manipulate molecules or particles in suspension and solution. Less well understood, though, is the ability of this phenomenon to generate circulatory fluid flow, and how this enables and enhances continuous particle capture. Here, we perform a comprehensive study of a low-voltage ICP, demonstrating a new electrokinetic method for extracting submicron particles via flow-enhanced particle redirection. To do so, a 2D-FEM model solves the Poisson–Nernst–Planck equation coupled with the Navier–Stokes and continuity equations. Four distinct operational modes (Allowed, Blocked, Captured, and Dodged) were recognized as a function of the particle’s charges and sizes, resulting in the capture or release from ICP-induced vortices, with the critical particle dimensions determined by appropriately tuning inlet flow rates (200–800 [µm/s]) and applied voltages (0–2.5 [V]). It is found that vortices are generated above a non-dimensional ICP-induced velocity of U*=1, which represents an equilibrium between ICP velocity and lateral flow velocity. It was also found that in the case of multi-target separation, the surface charge of the particle, rather than a particle’s size, is the primary determinant of particle trajectory. These findings contribute to a better understanding of ICP-based particle separation and isolation, as well as laying the foundations for the rational design and optimization of ICP-based sorting systems

Capillary-Force-Assisted Self-Assembly (CAS) of Highly Ordered and Anisotropic Graphene-Based Thin Films

We report capillary-force-assisted self-assembly (CAS) as a method for preparation of thin films of chemically reduced graphene oxide (rGO) with unidirectional organization of rGO sheets. The films were initiated at the contact line of the air–liquid–solid interface and form directly on solid substrates dipped in an isotropic colloidal suspension of rGO. Assisted by capillary forces at the contact line, the suspension undergoes an isotropic-to-anisotropic phase transition and becomes aligned with the film growth direction as the contact line moves across the substrate surface. We determined the degree of order in rGO films and assemblies by birefringence and diattenuation imaging. The slow axis of the rGO platelets within the CAS films displayed a narrow angular distribution (±3°) within a film area of 1 mm², resulting in the highest possible order parameter (<i>S</i>) of ∼1 with 8-fold enhancement of electrical conductivity compared to films formed by traditional techniques such as filtration. Our straightforward film fabrication technique is scalable to produce large areas of films, and by controlling the rates of convective to diffusive mass transport, films with varying degree of order can be produced

Numerical and Experimental Study of Cross-Sectional Effects on the Mixing Performance of the Spiral Microfluidics

Mixing at the microscale is of great importance for various applications ranging from biological and chemical synthesis to drug delivery. Among the numerous types of micromixers that have been developed, planar passive spiral micromixers have gained considerable interest due to their ease of fabrication and integration into complex miniaturized systems. However, less attention has been paid to non-planar spiral micromixers with various cross-sections and the effects of these cross-sections on the total performance of the micromixer. Here, mixing performance in a spiral micromixer with different channel cross-sections is evaluated experimentally and numerically in the Re range of 0.001 to 50. The accuracy of the 3D-finite element model was first verified at different flow rates by tracking the mixing index across the loops, which were directly proportional to the spiral radius and were hence also proportional to the Dean flow. It is shown that higher flow rates induce stronger vortices compared to lower flow rates; thus, fewer loops are required for efficient mixing. The numerical study revealed that a large-angle outward trapezoidal cross-section provides the highest mixing performance, reaching efficiencies of up to 95%. Moreover, the velocity/vorticity along the channel length was analyzed and discussed to evaluate channel mixing performance. A relatively low pressure drop (&lt;130 kPa) makes these passive spiral micromixers ideal candidates for various lab-on-chip applications

Rapid and Continuous Cryopreservation of Stem Cells with a 3D Micromixer

Cryopreservation is the final step of stem cell production before the cryostorage of the product. Conventional methods of adding cryoprotecting agents (CPA) into the cells can be manual or automated with robotic arms. However, challenging issues with these methods at industrial-scale production are the insufficient mixing of cells and CPA, leading to damage of cells, discontinuous feeding, the batch-to-batch difference in products, and, occasionally, cross-contamination. Therefore, the current study proposes an alternative way to overcome the abovementioned challenges; a highly efficient micromixer for low-cost, continuous, labour-free, and automated mixing of stem cells with CPA solutions. Our results show that our micromixer provides a more homogenous mixing of cells and CPA compared to the manual mixing method, while the cell properties, including surface markers, differentiation potential, proliferation, morphology, and therapeutic potential, are well preserved