Directed Assembly of Liquid Metal–Elastomer Conductors for Stretchable and Self-Healing Electronics

Growing interest in soft robotics, stretchable electronics, and electronic skins has created demand for soft, compliant, and stretchable electrodes and interconnects. Here, dielectrophoresis (DEP) is used to assemble, align, and sinter eutectic gallium indium (EGaIn) microdroplets in uncured poly(dimethylsiloxane) (PDMS) to form electrically conducting microwires. There are several noteworthy aspects of this approach. 1) Generally, EGaIn droplets in silicone at loadings approaching 90 wt% remain insulating and form a conductive network only when subjected to sintering. Here, DEP facilitates assembly of EGaIn droplets into conductive microwires at loadings as low as 10 wt%. 2) DEP is done in silicone for the first time, enabling the microwires to be cured in a stretchable matrix. 3) Liquid EGaIn droplets sinter during DEP to form a stretchable metallic microwire that retains its shape after curing the silicone. 4) Use of liquid metal eliminates the issue of compliance mismatch observed in soft polymers with solid fillers. 5) The silicone–EGaIn “ink” can be assembled by DEP within the crevices of severely damaged wires to create stretchable interconnects that heal the damage mechanically and electrically. The DEP process of this unique set of materials is characterized and the interesting attributes enabled by such liquid microwires are demonstrated.     

Inhibition of Golgi mannosidase II with mannostatin A analogues: synthesis, biological evaluation, and structure-activity relationship studies

Mannostatin and aminocyclopentitetrol analogues with various substitutions at the amino function were synthesized. These compounds were tested as inhibitors of human Golgi and lysosomal alpha-mannosidases. Modification of the amine of mannostatin had only marginal effects, whereas similar modifications of aminocyclopentitetrol led to significantly improved inhibitors. Ab initio calculations and molecular docking studies were employed to rationalize the results. It was found that mannostatin and aminocyclopentitretrol could bind to Golgi alpha-mannosidase II in a similar mode to that of the known inhibitor swainsonine. However, due to the flexibility of the five-membered rings of these compounds, additional low-energy binding modes could be adopted. These binding modes may be relevant for the improved activities of the benzyl-substituted compounds. The thiomethyl moiety of mannostatin was predicted to make favorable hydrophobic interactions with Arg228 and Tyr727 that would possibly account for its greater inhibitory activity.     

Physical barrier type abuse-deterrent formulations: monitoring sintering-induced microstructural changes in polyethylene oxide placebo tablets by near infrared spectroscopy (NIRS)

Objective: The monitoring and evaluation of sintering-induced tablet strength of a polyethylene oxide (PEO) based placebo tables was accomplished using infrared spectroscopy (NIRS).

Significance: Evaluation of high molecular weight PEO-based tablet matrices for abuse deterrent formulation applications is an analytical challenge. NIRS is one tool that can provide physical and chemical evaluation of this polymer and tablet system. In addition, the use of NIRS as a process analytical tool (PAT) to monitor oven sintering of pharmaceutical tablets has not been recorded in the literature. The multiplicative scattering correction (MSC) algorithm was also successfully applied as a new and fast way to calculate NIRS spectral slopes and intercepts to build models against tablet tensile strength with respect to sinter time.

Methods: Both spectral slope regression (SSR) and spectral intercept regression (SIR) models were compared to commonly used partial least squares analysis (PLS) to evaluate placebo PEO based pharmaceutical tablets comprised of PEO at 70, 50, 30% w/w that were compressed at two solid fraction (SF) levels.

Results: All three regression techniques, PLS, SSR, SIR, were evaluated for robustness and reliability and physical relevancy to the system studied. The methods were ranked in utility with SSR being the best method followed by SIR then PLS.

Conclusions: The MSC algorithm was presented to quickly calculate spectral slopes and intercepts for use in SSR and SIR analysis. SSR models were successfully applied and assessed as the optimal modeling technique to monitor sintering of PEO-based matrix tablets.     

Analysis and mitigation of voltage disturbances at an industrialcustomer's corporate campus

This paper presents the analysis of voltage sag data collected over several years at an industrial customer's corporate campus. Facilities on the campus include office buildings, pilot plants, R&D laboratories, chiller plants and boiler plants. The paper examines the “cause and effect” of voltage dips to the processes at the campus. It also details what the utility and the industrial customer did, or is doing, to mitigate additional dips to the campus. The determination of the final configuration of the power distribution system and its effect on the customer's power quality is also discussed     

The effects of static and adaptive performance feedback in game-based training

Training in virtual environments (VEs) has the potential to establish mental models and task mastery while providing a safe environment in which to practice. Performance feedback is known to contribute to this learning; however, the most effective ways to provide feedback in VEs have not been established. The present study examined the effects of differing feedback content, focusing on adaptive feedback. Participants learned search procedures during multiple missions in a VE. A control group received only a performance score after each mission. Two groups additionally received either detailed or general feedback after each mission, while two other groups received feedback that adapted based on their performance (either detailed-to-general, or general-to-detailed). Groups that received detailed feedback from the start of training had faster performance improvement than all other groups; however, all feedback groups showed improved performance and by the fourth mission performed at levels above the control group. Results suggest that detailed feedback early in the training cycle is the most beneficial for the fastest learning of new task skills in VEs.     

A method of HIV-1 inactivation compatible with antibody-based depletion of abundant proteins from plasma

We have examined several methods, including heat treatment and treatment with detergents, to inactivate HIV-1 present in plasma to be depleted of abundant proteins utilizing an antibody-based technology. Treatment with Triton X-100 was not compatible with abundant protein depletion with an antibody column and heat treatment alters the composition of the plasma proteome. However, treatment with 1.2% N-octylglucoside for 5?min completely inhibited HIV-1 infectivity. The detergent was easily removed through buffer exchange, and this treatment had no discernable effect on protein depletion.     

Visual field magnification and touch perception when exploring surfaces with the index finger and a rigid instrument

OBJECTIVE: The aim of this project was to compare texture discrimination when both touch and vision were perturbed. BACKGROUND: Texture discrimination is important in the workplace. How textures are identified with the finger and with instruments when vision is magnified with lenses or video cameras is unclear. METHOD: Sandpaper was explored with the index finger or a metal instrument (hemostat), using normal or magnified vision. The forces generated during exploration were measured, and participants rated surface roughness. RESULTS: With the finger, the perception of roughness was unaffected with magnification; with the instrument, magnified surfaces were perceived as rougher (p < .05). Forces during finger exploration were unaffected by magnification; forces with the instrument increased under magnification (p < .05). CONCLUSION: Visual characteristics of the working field can influence the exploration and perception of materials. With the finger, mechanoreceptors that directly detect textures are activated, and with the instrument, receptors sensitive to vibrations are stimulated. APPLICATION: The higher forces produced when using instruments under magnification could lead to material damage. Attenuated perception of texture when exploring with tools may lead to difficulty in accurate touch perception. This could create problems in industrial tasks such as grading wool or identifying surface imperfections on manufactured materials, as well as in clinical settings such as dentistry or surgery in which instruments are used during tissue identification.     

Changes in trunk muscle activation and lumbar-pelvic position associated with abdominal hollowing and reach during a simulated manual material handling task

The purpose of this study was to investigate the effect of abdominal hollowing (AH) on trunk muscle activation and lumbar-pelvic motion during a controlled lift and replace task. Surface electromyograms were recorded from five abdominal and two back muscle sites. Sagittal lumbar-pelvic motion was recorded by video. Subjects lifted a 3.8 kg load in normal, maximum and extreme reaches, first while performing their preferred lifting style (PLS) and then maintaining an AH technique. The external oblique muscle site activities were significantly higher (p < 0.05) for the AH technique (ranging from 7-20% of maximal voluntary activation (MVIC)) than at any of the abdominal sites for the PLS (ranging from 2-10% MVIC). Differences were found among abdominal sites for the AH, but not for the PLS. The back muscle site activities (ranging from 9-30% MVIC) were significantly higher (p < 0.05) than for any of the abdominal muscles for all conditions, except for the anterior external oblique for AH. The pelvic and lumbar angles changed significantly (p < 0.05) between normal and maximal reaches and between techniques. The AH technique altered abdominal muscle activation amplitudes, with minimal differences in trunk extensors compared to the PLS. The AH resulted in more posterior pelvic tilt.     

Microscopic investigations of chemo-mechanical polishing of tungsten

The influence of aqueous solutions of KNO₃, KClO₃, and KIO₃ on tungsten surfaces has been investigated in terms of the degree of surface oxidation, metal dissolution and interfacial friction. The surface properties of tungsten films have been measured ex-situ with X-ray photoelectron spectroscopy and in situ with atomic force microscopy. Measurements of the surface composition reveal a greater degree of oxidation for surfaces treated in solutions of KIO₃ in comparison to the other solutions. This increase in surface oxidation is correlated to a greater rate of localized film dissolution that occurs under the action of the scanning probe tip. In turn, the process of material removal is the predominant origin of the higher interfacial friction measured at tungsten surfaces immersed in KIO₃ solutions, as compared to KClO₃ and KNO₃ solutions. Collectively, these measurements portray a fundamental pathway of material removal at tungsten surfaces in the presence of oxidizing species and highlight complementary roles of chemical and mechanical action.