Adopting Maximum Pupil Diameter to Detect Subtle Usability Issues of a Smartphone Application, Conflict Solver

With the increasing popularity and unparalleled ubiquity of smartphones, researchers in various fields are designing and developing novel applications for this platform as part of the solution to the challenging problems they face. Usability lies at the core of the user experience of such applications. However, the assessments used are often limited to summative and post-event methods, which can overlook subtle yet impactful issues. Objective and instantaneous measures of cognitive workloads provide a solution to this shortcoming. Our previous research has established the reliability of maximum pupil dilation, measured with Tobii Pro Nano, as a preeminent indicator of cognitive workload surges in mobile application users. In this study, we used this measure to locate user cognitive workload peaks while using Conflict Solver and discovered subtle user interface issues that were not reported in the post-usability interview. A total of 30 participants completed a Conflict Solver usability experiment with two phases. In phase 1, the participants performed two “Add a Term” tasks on the original Conflict Solver, followed by a semi-structured interview about their experience with the application. A few subtle usability issues with a drop-down menu were detected through identifying user cognitive workload peaks. In phase 2, the same participants completed the same tasks on Conflict Solver with a redesigned and extended drop-down menu. The results showed that the new design solved the usability issues, and the participants became more favor the drop-down menu over the input box. In conclusion, including maximum pupil dilation into the usability assessment toolkit would provide a more objective and comprehensive usability assessment of a smartphone application. It can also be used to verify the successfulness of a user interface design solution.</p

Designing Recognition Molecules and Tailoring Functional Surfaces for In Vivo Monitoring of Small Molecules in the Brain

ConspectusThe in vivo analysis of chemical signals in brain extracellular fluid (ECF) using implanted electrochemical biosensors is a vital way to study brain functions and brain activity mapping. This approach offers excellent spatial (10–200 μm) and temporal (approximately second) resolution and the major advantage of long-term stability. By implantation of a microelectrode in a specific brain region, changes in the concentration of a variety of ECF chemical species can be monitored through applying a suitable electrical signal and, typically, recording the resulting Faradaic current. However, the high performance requirements for in vivo biosensors greatly limit our understanding of the roles that biomolecules play in the brain. Since a large number of biological species, including reactive oxygen species (ROS), metal ions, amino acids, and proteins, coexist in the brain and interact with each other, developing in vivo biosensors with high selectivity is a great challenge. Meanwhile, it is difficult to quantitatively determine target molecules in the brain because of the variation in the distinct environments for monitoring biomolecules in vitro and in vivo. Thus, there are large errors in the quantification of concentrations in the brain using calibration curves obtained in artificial cerebrospinal fluid (aCSF). More importantly, to gain a full understanding of the physiological and pathological processes in the brain, the development of novel approaches for the simultaneous determination of multiple species in vivo is urgently needed.This Account provides insight into the basic design principles and criteria required to convert chemical/electrochemical reactions into electric signals, while satisfying the increasing requirements, including high selectivity, sensitivity, and accuracy, for the in vivo analysis of biomolecules in the brain. Recent developments in designing various functional surfaces, such as self-assembled monolayers, gold nanostructures, and nanostructured semiconductors for facilitating electron transfer from specific enzymes, including superoxide dismutase (SOD), and further application to an O₂^•– biosensor are summarized. This Account also aims to highlight the design principles for the selective biosensing of Cu²⁺ and pH in the brain through the rational design and synthesis of specific recognition molecules. Additionally, electrochemical ratiometric biosensors with current signal output have been constructed to correct the effect of distinct environments in a timely manner, thus greatly improving the accuracy of the determination of Cu²⁺ in the live brain. This method of using a built-in element has been extended to biosensors with the potential signal output for in vivo pH analysis. More importantly, the new concept of both current and potential signal outputs provides an avenue to simultaneously determine dual species in the brain.The extension of the design principles and developed strategy demonstrated in this Account to other biomolecules, which may be closely correlated to the biological processes of brain events, is promising. The final section of this Account outlines potential future directions in tailoring functional surfaces and designing recognition molecules based on recent advances in molecular science, nanoscience and nanotechnology, and biological chemistry for the design of advanced devices with multiple target species to map the molecular imaging of the brain. There are still opportunities to engineer surfaces that improve on this approach by constructing implantable, multifunctional nanodevices that promise to combine the benefits of multiple sensing and therapeutic modules

Synthesis, Reactions, and Structural and NMR Features of [2.2]Metacyclophane Monoenes and Their Tricarbonylchromium and Cyclopentadienyliron(+) Complexes

8,16-Dimethyl-, 5,8,13,16-tetramethyl-, and 4,6,8,12,14,16-hexamethyl[2.2]metacyclophanene have been synthesized from the corresponding methyl-substituted 3-thia[3.2]metacyclophane precursors via a Wittig rearrangement−Hofmann elimination procedure. Simple addition of bromine or similar electrophiles to the bridge double bond of the cyclophane monoenes did not occur; rather, the methyl-substituted dihydropyrenes were formed. However, mono- and bis-tricarbonylchromium and mono-cyclopentadienyliron complexes were obtained using ligand-exchange reactions. Addition of bromine to the cyclophane bridge double bond of the iron complex did occur, but unusually slowly. Surprisingly, debromination rather than dehydrobromination occurred when the dibromo addition product was treated with a variety of bases. Photoisomerization of the monoenes and nucleophilic substitution of the metal complexes was also investigated. The geometries of the monoenes and their complexes were compared to the cyclophanes and the cyclophanedienes and to the monothia- and dithiacyclophanes, by comparison of X-ray and calculated structural data and NMR spectroscopic data. Introduction of double bonds into the cyclophane bridges causes the cyclophane step to be less steep but increases distortion of the internal atoms out of the plane of the benzene rings. Making the bridges nonidentical also causes a sideways twist of the step

Screened α‑Helix Peptide Inhibitor toward SARS-CoV‑2 by Blocking a Prion-like Domain in the Receptor Binding Domain

A new peptide inhibitor was designed and optimized from an α-helix-rich peptide library specifically toward the critical prion-like domain (PLD) of SARS-CoV-2. It compactly blocked the S1 protein and potently neutralized the pseudovirus which shows promising potential for prophylactic and treatment of COVID-19

Highly Stable Electrochemical Probe with Bidentate Thiols for Ratiometric Monitoring of Endogenous Polysulfide in Living Mouse Brains

The lack of reliable approaches for real-time measurement and quantification of polysulfides (H2Sn) in vivo greatly limits the exploration of their potential roles in brain functions. Herein, an electrochemical probe, 4-(5-(1,2-dithiolan-3-yl)­pentanamido)-1,2-phenylene bis­(2-fluoro-5-nitrobenzoate) (FP2), was rationally designed and created for determination of H2Sn. The bis-electrophilic groups of FP2 could specifically recognize two −SH groups in H2Sn and trigger the generation of an electroactive pyrocatechol moiety, resulting in a well-defined faradic current signal at ∼0.24 V (vs Ag/AgCl). Meanwhile, bidentate thiols were designed as anchoring sites to greatly improve the assembled stability of FP2 at the Au surface, which efficiently defended the interference of glutathione (GSH) with a current decrease of less than 5.2% even after long-term measurements in 5 mM GSH for 3 h. In addition, a stable inner reference molecule with dithiols, α-lipoic acid ferrocenylamide (FcBT), was synthesized to construct a ratiometric electrochemical strategy for in vivo determination of H2Sn through one-step coassembling with FP2 via double S–Au bonds. The present ratiometric strategy demonstrated high selectivity for real-time tracking of H2Sn in a linear range of 0.25–20 μM. Eventually, the developed microelectrode with high selectivity, accuracy, and stability was employed for in vivo assaying of H2Sn in mouse brains with ischemia

Comparison with state-of-the-art trackers on VOT2016 in terms of EAO, A and R.

Comparison with state-of-the-art trackers on VOT2016 in terms of EAO, A and R.</p

Illustration of DOSiam.

It consists of the feature extraction subnetwork and cross-correlation operation. The feature extraction subnetwork contains conventional convolution layers and DO-Conv.</p

Ratiometric Electrochemical Sensor for Selective Monitoring of Cadmium Ions Using Biomolecular Recognition

A selective, accurate, and sensitive method for monitoring of cadmium ions (Cd²⁺) based on a ratiometric electrochemical sensor was developed, by simultaneously modifying with protoporphyrin IX and 6-(ferroceney) hexanethiol (FcHT) on Au particle-deposited glassy carbon electrode. On the basis of high affinity of biomolecular recognition between protoporphyrin IX and Cd²⁺, the functionalized electrode showed high selectivity toward Cd²⁺ over other metal ions such as Cu²⁺, Fe³⁺, Ca²⁺, and so on. Electroactive FcHT played the role as the inner reference element to provide a built-in correction, thus improving the accuracy for determination of Cd²⁺ in the complicated environments. The sensitivity of the electrochemical sensor for Cd²⁺ was enhanced by ∼3-fold through the signal amplification of electrodeposited gold nanoparticles. Accordingly, the present ratiometric method demonstrated high sensitivity, broad linear range from 100 nM to 10 μM, and low detection limit down to 10 nM (2.2 ppb), lower than EPA and WHO guidelines. Finally, the ratiometric electrochemical sensor was successfully applied in the determination of Cd²⁺ in water samples, and the obtained results agreed well with those obtained by the conventional ICP-MS method

Illustration of DO-Conv.

The deep convolution and conventional convolution kernel are included in DO-Conv. ∘ means the depthwise convolution operator and * means convolution operator.</p

Potential-Dependent Adsorption and Transfer of Poly(diallyldialkylammonium) Ions at the Nitrobenzene|Water Interface

Electrochemically driven adsorption and partition of a series of poly(diallyldialkylammonium) ions (PDADAA⁺: alkyl = methyl, ethyl, propyl, and butyl) at the nitrobenzene (NB)|water (W) interface have been studied using voltammetry and electrocapillary measurements. When the phase-boundary potential, Δφ, that is, the inner potential of the W phase referred to that of the NB phase, is negative, poly(diallyldimethylammonium) (PDADMA⁺) shows little surface activity. The scanning of Δφ in the positive direction induces, first, the adsorption of PDADMA⁺ at the interface and, then, the desorption of adsorbed PDADMA⁺ ions into the NB phase, followed by the diffusion-limited transfer of PDADMA⁺ from W to NB. The elongation of the dialkyl chains gives the stronger surface activity of PDADAA⁺ even when Δφ < 0. The PDADAA⁺ polyions studied are only slightly more hydrophilic than the corresponding monomers. However, the polycationic character of PDADAA⁺ renders the adsorption, desorption, and ion transfer strongly dependent on Δφ and gives rise to unusual, M-shaped electrocapillary curves. The interplay of adsorption–desorption and ion transfer of PDADAA⁺ ions induces the electrochemical instability of the interface and the emulsion formation on the NB side of the interface