CLARA: Classifying and Disambiguating User Commands for Reliable Interactive Robotic Agents

In this paper, we focus on inferring whether the given user command is clear, ambiguous, or infeasible in the context of interactive robotic agents utilizing large language models (LLMs). To tackle this problem, we first present an uncertainty estimation method for LLMs to classify whether the command is certain (i.e., clear) or not (i.e., ambiguous or infeasible). Once the command is classified as uncertain, we further distinguish it between ambiguous or infeasible commands leveraging LLMs with situational aware context in a zero-shot manner. For ambiguous commands, we disambiguate the command by interacting with users via question generation with LLMs. We believe that proper recognition of the given commands could lead to a decrease in malfunction and undesired actions of the robot, enhancing the reliability of interactive robot agents. We present a dataset for robotic situational awareness, consisting pair of high-level commands, scene descriptions, and labels of command type (i.e., clear, ambiguous, or infeasible). We validate the proposed method on the collected dataset, pick-and-place tabletop simulation. Finally, we demonstrate the proposed approach in real-world human-robot interaction experiments, i.e., handover scenarios

Nanometric Water Channels in Water-in-Salt Lithium Ion Battery Electrolyte

Lithium-ion batteries (LIBs) have been deployed in a wide range of energy-storage applications and helped to revolutionize technological development. Recently, a lithium ion battery that uses superconcentrated salt water as its electrolyte has been developed. However, the role of water in facilitating fast ion transport in such highly concentrated electrolyte solutions is not fully understood yet. Here, femtosecond IR spectroscopy and molecular dynamics simulations are used to show that bulk-like water coexists with interfacial water on ion aggregates. We found that dissolved ions form intricate three-dimensional ion–ion networks that are spontaneously intertwined with nanometric water hydrogen-bonding networks. Then, hydrated lithium ions move through bulk-like water channels acting like conducting wires for lithium ion transport. Our experimental and simulation results indicate that water structure-breaking chaotropic anion salts with a high propensity to form ion networks in aqueous solutions would be excellent candidates for water-based LIB electrolytes. We anticipate that the present work will provide guiding principles for developing aqueous LIB electrolytes. © 2018 American Chemical Societ

Dynamic Water Promotes Lithium-Ion Transport in Superconcentrated and Eutectic Aqueous Electrolytes

Superconcentrated aqueous electrolytes have shown promise as safe and high-voltage lithium-ion battery (LIB) electrolytes. However, the interplay of lithium-ion solvation structure and dynamics with fast Li-ion transport has not been elucidated yet. Here, we combine the ultrafast femtosecond mid-IR spectroscopy, dielectric relaxation spectroscopy, pulsed-field gradient NMR, and molecular dynamics simulation for investigating the solvation structure and Li-ion transport mechanism in superconcentrated aqueous electrolytes. We found the existence of water molecules with vibrational and rotational properties very similar to those of bulk water, even at extremely high salt concentrations (28 m). Our experimental results show that the electrolytes have a heterogeneous solvation environment, and bulk-like water molecules promote fast Li-ion transport. We anticipate that the molecular understanding of the superconcentrated aqueous electrolytes obtained here would facilitate the design of solvation structures to overcome the limit of dilute LIB electrolytes.11Nsciescopu

Tailoring Transition Dipole Moment in Colloidal Nanocrystal Thin Film on Nanocomposite Materials

Controlling the transition dipole moment is extremely important for various photophysical characteristics in semiconductors. Especially, suppression of Auger recombination in quantum dots (QDs) is essential for the development of novel applications, including bioimaging, lasing, and optoelectronic devices. To date, most of the studies on the Auger process are conducted on the basis of manipulating the material property such as wavefunction of electron and hole, energy band, and confinement potential. However, a new way of tuning the Auger process using nanocomposite materials is not reported. In this work, the biexciton Auger recombination (BAR) process in CdSe/CdS(1 ML) nanocrystal thin-film is successfully controlled by introducing nanocomposite materials. Performing pump intensity-dependent transient absorption experiments, a significant reduction (up to 30%) of BAR rate is observed in the presence of nanocomposite structures. This notable suppression effect is attributed to the modulation of the net transition dipole moment. These findings will provide further insight into the rational design of QDs combining with a nanostructure that efficiently suppresses Auger recombination rates.11Nsciescopu

Ultrafast intraband Auger process in self-doped colloidal quantum dots

Investigating the separate dynamics of electrons and holes has been challenging, although it is critical for the fundamental understanding of semiconducting nanomaterials. n-Type self-doped colloidal quantum dots (CQDs) with excess electrons occupying the low-lying state in the conduction band (CB) have attracted a great deal of attention because of not only their potential applications to infrared optoelectronics but also their intrinsic system that offers a platform for investigating electron dynamics without elusive contributions from holes in the valence band. Here, we show an unprecedented ultrafast intraband Auger process, electron relaxation between spin orbit coupling states, and exciton-to-ligand vibrational energy transfer process that all occur exclusively in the CB of the self-doped beta-HgS CQDs. The electron dynamics obtained by femtosecond mid infrared spectroscopy will pave the way for further understanding of the blinking phenomenon, disproportionate charging in light-emitting diodes, and hot electron dynamics in higher quantum states coupled to surface states of CQDs.11Nsciescopu

Cyanamide as an Infrared Reporter: Comparison of Vibrational Properties between Nitriles Bonded to N and C Atoms

Infrared (IR) probes based on terminally blocked β-cyanamidoalanine (AlaNHCN) <b>1</b> and <i>p</i>-cyanamidophenylalanine (PheNHCN) <b>2</b> were synthesized, and the vibrational properties of their CN stretch modes were studied using Fourier transform infrared (FTIR) and femtosecond IR pump–probe spectroscopies in combination with quantum chemical calculations. From FTIR studies, it is found that the transition dipole strengths of the cyanamide (NHCN) group in <b>1</b> and <b>2</b> are much larger than those of the nitrile (CN) group but comparable to those of the isonitrile (NC) and azido (N₃) groups in their previously studied analogs. The CN stretch frequencies in <b>1</b> and <b>2</b> are red-shifted from those in their nitrile analogs but more blue-shifted from the NC and N₃ stretch frequencies in their isonitrile and azido analogs. The much larger transition dipole strength and the red-shifted frequency of the cyanamide relative to nitrile group originates from the n → π* interaction between the N atom’s nonbonding (n) and CN group’s antibonding (π*) orbitals of the NHCN group. Unlike aliphatic cyanamide <b>1</b>, aromatic cyanamide <b>2</b> shows a complicated line shape of the CN stretch spectra. Such a complicated line shape arises from the Fermi resonance between the CN stretch mode of the NHCN group and one of the overtones of the phenyl ring vibrations and can be substantially simplified by deuteration of the NHCN into NDCN group. From IR pump–probe experiments, the vibrational lifetimes of the CN stretch mode in <b>1</b> were determined to be 0.58 ± 0.04 ps in D₂O and 0.89 ± 0.09 ps in H₂O and those in <b>2</b> were determined to be 1.64 ± 0.13 ps in CH₃OD/dimethyl sulfoxide and 0.30 ± 0.05 and 2.62 ± 0.26 ps in CH₃OH. The short time component (0.30 ± 0.05 ps) observed for <b>2</b> in CH₃OH is attributed to the vibrational relaxation through Fermi resonance. These vibrational lifetimes are close to those of the nitrile and azido groups but shorter than those of the isonitrile group. Consequently, cyanamide behaves like an apparent vibrational hybrid of nitrile and isonitrile in that cyanamide is similar to nitrile in vibrational frequency and lifetime but to isonitrile in transition dipole strength. It is believed that cyanamide has the potential to be a strongly absorbing IR reporter of the conformational and environmental structure and dynamics of biomolecules in comparison to nitrile, a weak absorber

Two-Dimensional Infrared Spectroscopy and Molecular Dynamics Simulation Studies of Nonaqueous Lithium Ion Battery Electrolytes

Lithium ion battery (LIB) technology is undoubtedly indispensable to modern life. However, despite enormous and extended effort to improve LIB performance, our understanding of the underlying principles and mechanisms of lithium ion transport in nonaqueous LIB electrolytes remained limited until recently. There is a particular lack of knowledge of the microscopic solvation structures and fluctuation dynamics around charge carriers in real electrolytes. Typical electrolytes found in commercially available LIBs consist of lithium salts and mixed carbonate solvents, with the latter playing an essential role in promoting lithium ion transport and forming an electrically stable solid electrolyte interphase. Although a number of linear spectroscopic studies of LIB electrolytes aiming at understanding the complex nature of lithium ion solvation processes have been reported, the notion that each lithium ion is strongly solvated by carbonate molecules to form a long-lasting solvation sheath structure has remained the subject of intense debate. Here, we present the results of FTIR, fs IR pump-probe, two-dimensional IR spectroscopy, and molecular dynamics simulations reported by us and others and discuss the possible interplay of picosecond solvation dynamics and macroscopic ion transport processes within the framework of the fluctuation-dissipation relationship. Further, by measuring the time-dependent fluctuations and spectral diffusions of carbonate carbonyl stretch modes that act as excellent infrared probes for the local electrostatic environment, we show that lithium cations are not only solvated by carbonate molecules but also interact with counteranions at equilibrium depending on solvent composition. Molecular dynamics simulations support the notion that rapid chemical exchanges between carbonate solvent molecules in the first and outer solvation shells are critical for describing mobile lithium ion transport phenomena. We thus anticipate that time-resolved coherent multidimensional vibrational spectroscopy is capable of providing decisive evidence on the ultrafast solvent dynamics of various electrolytes, which is potentially helpful for designing improved and more efficient LIB electrolytes in the future. © 2019 American Chemical Societ