Abstract We theoretically study the collision dynamics of uncharged, conducting droplets settling under the influence of gravity in the presence of an external electric field. Our study demonstrates that the attractive forces induced by an external electric field can overcome lubrication resistance, facilitating surface-to-surface contact between two spherical conductors within a finite time. For water droplets moving in air, continuum lubrication theory fails when the gap between droplets becomes less than the mean free path of air molecules. To account for this, we incorporate noncontinuum lubrication effects in the collision calculations. By numerically computing the relative trajectories of the droplets, we assess how collision efficiency depends on the droplet size ratio, noncontinuum lubrication effects, the angle between the electric field and gravity, electric field strength, and van der Waals forces. Our findings reveal that electric field–induced forces significantly enhance collision efficiency, highlighting their critical role in droplet collision dynamics.

The photophysical properties of four fluorescent probes based on 4-ethynyl-2,1,3-benzothiadiazole (BTD) are investigated in Pluronic media (F127 and P123). Here, we employ a set of probes with distinct charge-transfer characteristics and different partitioning behaviours. This can enable validation of localization across different micellar domains. Combined with multiparametric sensing of variations in fluorescence parameters such as emission maximum (λmax), intensity, lifetime, and anisotropy, this strategy provides a better understanding of polarity, microviscosity, and rotational rigidity than single probes alone. The response and sensitivity of these probes for different fluorescence parameters towards microenvironmental changes in Pluronic micelles have been studied. Additionally, their sensing potentials are explored during the sol-gel phase transition in these media. These probes are classified according to their intramolecular charge transfer (ICT) features: (a) BTDPhCN and BTDPh with weaker ICT and (b) BTDPhOMe and BTDPhNMe2 with significant ICT features. Their strong sensitivity to polarity and viscosity change makes them ideal for studying amphiphilic microenvironments. Steady-state and time-resolved fluorescence (TRF) spectroscopy techniques were used to track sol-gel transitions and probe localization and temperature-induced microenvironmental changes. The results show that these probes are able to sense micellar sol and gel phases through emission shifts (λmax), fluorescence intensity variations, lifetime changes, and anisotropy changes. BTDPhCN and BTDPh exhibited blue shifts, indicating migration into the micellar core, while BTDPhOMe and BTDPhNMe2 displayed bathochromic shifts, suggesting expulsion to a more polar interfacial region. Fluorescence lifetime and anisotropy measurements confirmed the differential probe localization, with increased anisotropy in the gel phase indicating restricted molecular motion. Additionally, BTD probes help to elucidate microenvironmental variations associated with the change in Pluronic composition.

Photoabsorbers have been incorporated into inherently thermo-responsive liquid crystal polymers to impart photoresponsivity. We studied the effect of adding two azobenzene chromophores simultaneously into a liquid crystal polymer network (LCN) thin film through experiments and simulations. The chromophores are chosen such that one exhibits a photo-thermal effect, while the other exhibits both photo-thermal and photo-chemo-mechanical effects. The azobenzene dyes used are A3MA and DR1A with maximum absorbance at 365 nm and 483 nm, respectively. The photo-actuation experiments are performed at their respective absorption wavelengths, i.e., 365 nm and 455 nm. In addition, an intermediate wavelength of 395 nm is employed to study the actuation. It is observed that the dual dye films exhibit comparable tip displacements with lower maximum surface temperatures in comparison to single dye films with equal dye mole fractions. A comprehensive finite element model for simulating the combined photo-chemo and photo-thermal responses of dual dye LCN films is implemented. The attenuation depths of the individual dyes from the dual-dye films are determined and used for calculating the through-thickness intensity variation and steady state cis-mass fraction for respective illumination wavelengths. The simulations demonstrate good quantitative correlation with experimental observations.

Abstract Cross-education, a phenomenon where training one limb improves performance in the untrained limb, can be enhanced through mirror visual feedback (MVF), underpinning its potential for rehabilitating hemiparetic patients. While MVF-mediated enhancement is documented for simple motor tasks, its effectiveness in complex, fine finger movements remains underexplored. To address this gap, we developed a novel experimental setup to investigate MVF effects on cross-education for a unique typing task involving fine finger movements. The setup comprises three tightly synchronized systems: A novel typing device to implement the typing task, an IMU-based system for accurate real-time hand movement tracking, and a virtual reality (VR) system that provides normal or mirrored real-time replication of hand movements by virtual hands. Additionally, several methodologies and algorithms critical to the experimental task were developed: (1) Constructing participant-specific virtual hand models to accurately replicate thumb-to-phalanx touches. (2) An intuitive approach to manipulating quaternions for coordinate transformation and mirror animation. (3) Millisecond-level synchronization of movement and typing data. (4) Preventing false key press/release detections by filtering noise specific to the typing device. (5) Correcting reference frame misalignment between IMU sensors and their respective hand segments. Some of these methodologies contribute valuable tools to the hand biomechanics and VR research communities. Technical validation of the setup demonstrated robust real-time performance, millisecond-level data synchronization, and precise hand animation, confirming the system’s readiness for investigating MVF-based cross-education.

Antimony-based anodes offer high theoretical capacities but face critical challenges such as severe volume expansion and poor cycle life in rechargeable batteries. Developing a suitable dopant for Sb-based anodes and integrating these materials with nanofiber architectures presents a promising pathway to address these limitations. This study investigates the effect of Al doping in Sb alloy-based nanofibers by comparing antimony nanofibers (Sb-NF) with aluminum-doped Sb-NF (Sb0.95Al0.05-NF). In lithium-ion batteries (LIBs), Sb-NF remains electrochemically active up to a 10 C-rate, while Sb0.95Al0.05-NF sustains cyclability even at 30C-rate, delivering 73.9 mAh g-1. For sodium-ion batteries (SIBs), both anodes function up to 25C-rate, but Sb0.95Al0.05-NF achieves a reversible capacity of 117 mAh g-1, significantly outperforming Sb-NF, which delivers 50 mAh g-1. Long-term cycling studies on LIB show that Sb0.95Al0.05-NF retains nearly three times the capacity of Sb-NF after 300 cycles, with capacity retention of 14% and 9%, respectively. In SIBs, Sb0.95Al0.05-NF exhibits superior performance up to 200 cycles, however, both Sb-NF and Sb0.95Al0.05-NF electrodes are affected by electrolyte related degradation including sodium dendrite formation beyond 200 cycles. Cyclic voltammetry reveals higher diffusion coefficients for Sb0.95Al0.05-NF in both LIB and SIB configuration. These findings highlight the synergetic benefits of doping and nanofiber morphology in improving rate capability and cycling stability.

Microfluidic devices offer more accurate fluid flow control and lower reagent use for uniform nanoparticle synthesis than batch synthesis. Here, we propose a microfluidic device that synthesizes uniform iron oxide nanoparticles (IONPs) for highly efficient intracellular delivery. The 3D-printed device was fabricated, comprising two inlets in the T-shaped channel with an inner diameter of 2 mm, followed by a helical mixing channel with a single outlet. The unique geometries of this device enable accuracy and precision by allowing shortened reaction time and control fluid mixing, resulting in the production of homogenous NPs. By utilizing this device and using the co-precipitation method at room temperature, IONPs with an average cluster size of 90 nm were synthesized. The photothermal property of IONPs was explored through light-matter interaction using a nanosecond (ns) pulse laser at 1064 nm and a fluence of 35 mJ cm-2, which helps to create transient cell membrane pores and deliver small to large biomolecules into cells by a simple diffusion process. We carried out highly efficient intracellular delivery using propidium iodide (PI) (668 Da), dextran (3 kDa), 6159 bp pcDNA3-enhanced green fluorescent protein (EGFP) and Cy-5-β-galactosidase enzyme (465 kDa) into mouse fibroblast (L929), human cervical (SiHa) cancer cells, LN229, a human glioblastoma cell line, and human mesenchymal stem cells (hMSCs). The best results achieved for Cy-5-β-galactosidase enzyme transfection in hMSCs were 98.6% transfection efficiency and 98.6% cell viability. Thus, our platform might have potential applications in cell therapeutics and diagnostics.