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Graphene oxide (GO)-the oxidized form of graphene-is actively studied in various fields, such as energy, electronic devices, separation of water, materials engineering, and medical technologies, owing to its fascinating physicochemical properties. One major drawback of GO is its instability, which leads to the difficulties in product management. A physicochemical understanding of the ever-changing nature of GO can remove the barrier for its growing applications. Here, we evidencde the presence of intrinsic, metastable and transient GO states upon ripening. The three GO states are identified using a [Formula: see text] transition peak of ultraviolet-visible absorption spectra and exhibit inherent magnetic and electrical properties. The presence of three states of GO is supported by the compositional changes of oxygen functional groups detected via X-ray photoelectron spectroscopy and structural information from X-ray diffraction analysis and transmission electron microscopy. Although intrinsic GO having a [Formula: see text] transition at 230.5 ± 0.5 nm is stable only for 5 days at 298 K, the intrinsic state can be stabilized by either storing GO dispersions below 255 K or by adding ammonium peroxydisulfate., (© 2024. The Author(s).)

We present herein that carbon nanospaces are the key reaction space to improve the reversibility of the reaction of SnO 2 with Li-ions for lithium-ion batteries, demonstrated by both ex situ and in situ observations using high-resolution scanning transmission electron microscopy with electron energy loss spectroscopy. Conversion-type electrode materials, such as SnO 2 , undergo large volume changes and phase separation during the charge-discharge process, which lead to degradation in the battery performance. By confining the SnO 2 -Li reaction within carbon nanopores, the battery performance is improved. However, the exact phase changes of SnO 2 in the nanospaces are unclear. By directly observing the electrodes during the charge-discharge process, the carbon walls are capable of preventing the expansion of SnO 2 particles and minimizing the conversion-induced phase separation of Sn and Li 2 O on the sub-nanometer scale. Thus, nanoconfinement structures can effectively improve the reversibility performance of conversion-type electrode materials.

Standard clinical care of neonates and the ventilation status of human patients affected with coronavirus disease involves continuous CO 2 monitoring. However, existing noninvasive methods are inadequate owing to the rigidity of hard-wired devices, insubstantial gas permeability and high operating temperature. Here, we report a cost-effective transcutaneous CO 2 sensing device comprising elastomeric sponges impregnated with oxidized single-walled carbon nanotubes (oxSWCNTs)-based composites. The proposed device features a highly selective CO 2 sensing response (detection limit 155 ± 15 ppb), excellent permeability and reliability under a large deformation. A follow-up prospective study not only offers measurement equivalency to existing clinical standards of CO 2 monitoring but also provides important additional features. This new modality allowed for skin-to-skin care in neonates and room-temperature CO 2 monitoring as compared with clinical standard monitoring system operating at high temperature to substantially enhance the quality for futuristic applications., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 Elsevier B.V. All rights reserved.)

Plants and fungi classified as herbs are utilized for the maintenance of health in humans. In this study, to evaluate the beneficial effects of herbs, we investigated the phenolic content and antioxidative activity of 20 samples. Some herbs, including Cistanche herb, had high phenol levels and exhibited high activities for radical-scavenging and suppression of lipid peroxidation. Phenolic contents and antioxidative activities showed a high positive correlation. In contrast, some herbal medicines with low phenolic content exhibited high suppressive effects on lipid peroxidation, and it was thought that carotenoids contributed to their suppression. The results of this study are expected to support the clarification of the mechanism of herbal medicines in promoting wellness.

Perilla oil is a valuable food source of α-linolenic acids. However, its high reactivity with oxygen shortens its shelf-life after opening. This study investigated the antioxidative profiles of 15 plant materials, including herbs, and examined methods to suppress the oxidation of perilla oil using these plant materials. These plant materials had wide ranges of phenolic, carotenoid, and chlorophyll contents. They exhibit radical scavenging activities and suppress lipid peroxidation, which show highly positive correlations with the phenolic contents. Dipping most of the plant materials examined in perilla oil suppressed its oxidation, and the peroxide values of the oil mixtures indicated a negative correlation with the carotenoid and chlorophyll contents of the plant materials. The leaves of Angelica, Astragalus, and Thyme herbs exhibited the same effect as that of ascorbyl palmitate, which was used as a positive control after 8 wk of incubation in the dark. The suppression of lipid peroxidation was found to be related to the herbal contents of carotenoids and chlorophylls, rather than phenols. Hence, herbal leaves can suppress the oxidation of perilla oil in the dark. The oxidation of n-3 polyunsaturated fatty acids could be suppressed effectively by utilizing plant materials with abundant carotenoids and chlorophylls.

Large scale development of the 2D transition metal di-chalcogenides (TMDC) relies on landmark improvement in performance, which could emerge from nanostructuration. Using p-WS 2 nanoflakes with different degrees of exfoliation and fracturing, perspectives were provided to develop high-surface-area 2D p-WS 2 films for the photocatalytic hydrogen generation. The critical role of inter-nanoflakes contacts within high-surface-area 2D films was demonstrated, highlighting the benefit of plane/plane versus edge/plane contacts. Evidence of the high density of surface states displayed by these 2D films was provided through electrochemical measurements. In addition to operating as recombination centers, the surface states were shown to give rise to deleterious Fermi-level pinning (FLP), which dramatically decreased the efficiency of charge carrier separation. Lastly, promising strategies yielding FLP suppression via surface states modification were proposed. In particular, use of a multifunctional ultrathin film displaying healing, catalytic, and n-type semiconduction properties was shown to greatly enhance charge carrier separation and transport to the photo-electrode/electrolyte interface. When the 2D photoelectrodes were fabricated with the above prerequisites (i. e., a high proportion of plane/plane contacts and a successful surface states chemical modification), a photocurrent up to 4.5 mA cm -2 was achieved for the first time on 2D p-WS 2 photocathodes for hydrogen generation., (© 2022 Wiley-VCH GmbH.)

Robot-assisted gait training using a voluntary-driven wearable cyborg, Hybrid Assistive Limb (HAL), has been shown to improve the mobility of patients with neurological disorders; however, its effect on the quality of life (QOL) of patients is not clear. The aim of this study was to assess the effects of HAL-assisted gait training on QOL and mobility in patients with neuromuscular diseases (NMDs). Ten patients with NMDs (seven men and three women, mean age: 57 ± 11 years), with impairment in mobility but could walk alone with aids underwent two courses of gait training with HAL over 6 months, and the single course consisted of nine sessions of training for 4 weeks. We compared the findings of the 2 min walk test, 10 m walk test, the Short Form-36 (SF-36) questionnaire, and the Hospital Anxiety and Depression Scale at baseline, after the 1st training, before the 2nd training, and after the 2nd training using the Friedman test. A significant improvement was observed in the 2 min walking distance from baseline (93 ± 50 m) to after the 2nd training (115 ± 48 m, P = 0.034), as well as in the domains of vitality (P = 0.019) and mental component summary score (P = 0.019) of SF-36. The improvement in 10 m walking speed was significantly correlated with that in the physical functioning (R = 0.831, P = 0.003) and role physical (R = 0.697, P = 0.025) domains in the SF-36. Our findings suggest that HAL-assisted gait training is effective in improving QOL associated with mental health as well as gait ability in selected patients with NMDs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In this study, porous boron nitride (p-BN) with hexagonal phase boron nitride (h-BN) pore walls was synthesized using high-temperature calcination. Negligible variation in pore-wall structure can be observed in powder X-ray diffraction (XRD) profiles and infrared (IR) spectra. However, a highly stable p-BN with a stable pore structure even at 973 K under the oxidative conditions is obtained when synthesized at higher than 1573 K under nitrogen gas flow. For p-BN, this stability is obtained by generating h-BN microcrystals. Nitrogen adsorption-desorption isotherms at 77 K provide type-IV features and typical adsorption-desorption hysteresis, which suggests micropore and mesopore formation. Moreover, adsorption-desorption isotherms of Ar at 87 K are measured and compared with those of nitrogen. The relative adsorbed amount of nitrogen ( i.e. , the amount of nitrogen normalized by that of Ar at each relative pressure or adsorption potential value) on p-BN is considerably larger than that on microporous carbon at low-pressure regions, which suggests the existence of strong adsorption sites on the p-BN surface. In fact, the relative number of adsorbed nitrogen molecules to that of Ar on p-BN is, at most, 150%-200% larger than that on microporous carbon for the same adsorption potential state. Furthermore, additional adsorption enhancement to nitrogen between P / P 0 = 10 -5 can be observed for p-BN treated at 1673 K, which suggests the uniformly adsorbed layer formation of nitrogen molecules in the vicinity of a basal planar surface. Thus, unlike typical nanoporous sp -3 can be observed for p-BN treated at 1673 K, which suggests the uniformly adsorbed layer formation of nitrogen molecules in the vicinity of a basal planar surface. Thus, unlike typical nanoporous sp 2 carbons, p-BN materials have the potential to enhance adsorption for certain gas species because of their unique surface state., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The conventional approach for fabricating all-solid-state batteries has required a highly dense layer of electrode and electrolyte. Their close contact interface is not suitable for alloy- or conversion-based active materials because their large volume change in lithiation/delithiation reactions causes a collapse of the contact interface or reaction limitations under mechanical constriction. In this study, we propose that a SnO 2 -embedded porous carbon electrode shows high cyclability and high capacity even at high constraint pressure owing to the nanopores, which work as a buffer space for the large volume change accompanied with SnO 2 -Sn conversion reaction and Sn-Li alloying-dealloying reaction. A detailed investigation between structural parameters of the electrode material and charge-discharge properties revealed Li ion conduction in carbon nanopores from a solid electrolyte located outside as well as the optimal conditions to yield high performance. SnO 2 -loading (75 wt %) in carbon nanopores, which provides the buffer space corresponding to the inevitable volume expansion by full lithiation, brought out an excellent performance at room temperature superior to that in an organic liquid electrolyte system: a high capacity of 1023 mAh/g-SnO 2 at 50 mA/g, high capacity retention of 97% at 300th cycle at 300 mA/g, and high rate capability with over 75% capacity retention at 1000 against 50 mA/g, whose values are also superior to the system using the organic liquid electrolyte.

Isosteric heat of adsorption is exquisitely sensitive to structural changes in carbon surfaces based on the energetic behavior of the interactions between adsorbates and carbon materials. We discuss the relationships between porous structures, oxygen functional groups, and heat of adsorption based on the behavior of the heat of adsorption of polar and non-polar fluids on porous carbon materials with oxygen functional groups. The porosity and functional groups of porous carbon materials were estimated from N 2 adsorption isotherms at 77 K and temperature-programmed desorption. High-resolution adsorption isotherms of water, acetonitrile (polar fluid), and n-hexane (non-polar fluid) were measured on porous carbon materials with different pore size distributions and amounts of oxygen functional groups at various temperatures. The heats of adsorption were determined by applying the Clausius-Clapeyron equation to the adsorption isotherms. The heat of adsorption curves directly reflect the effects of interactions of fluid-oxygen functional groups, fluid-basal planes of pore walls, and fluid-fluid interfaces. In particular, the heat of adsorption curve of water is very sensitive to surface oxygen functional groups. This finding indicates the possibility of estimating the relative amounts of oxygen functional groups on porous carbon materials based on the amounts of water adsorbed at specific relative pressures., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Extensive research efforts are devoted to development of high performance all-solid-state lithium ion batteries owing to their potential in not only improving safety but also achieving high stability and high capacity. However, conventional approaches based on a fabrication of highly dense electrode and solid electrolyte layers and their close contact interface is not always applicable to high capacity alloy- and/or conversion-based active materials such as SnO 2 accompanied with large volume change in charging-discharging. The present work demonstrates that SnO 2 -embedded nanoporous carbons without solid electrolyte inside the nanopores are a promising candidate for high capacity and stable anode material of all-solid-state battery, in which the volume change reactions are restricted in the nanopores to keep the constant electrode volume. A prototype all-solid-state full cell consisting of the SnO 2 -based anode and a LiNi 1/3 Co 1 / 3 Mn 1/3 O 2 -based cathode shows a good performance of 2040 Wh/kg at 268.6 W/kg based on the anode material weight.

Fabrication of nanographene shows a promising route for production of designed porous carbons, which is indispensable for highly efficient molecular separation and energy storage applications. This process requires a better understanding of the mechanical properties of nanographene in their aggregated structure. We studied the structural and mechanical properties of nanographene monoliths compressed at 43 MPa over different times from 3 to 25 h. While in monoliths compressed over shorter time adsorption isotherms of Ar at 87 K or N 2 at 77 K exhibited a prominent hysteresis due to presence of predominant mesopores, compression for long time induces a low pressure hysteresis. On the other hand, compression for 25 h increases the microporosity evaluated by Ar adsorption, not by N 2 adsorption, indicating that 25 h compression rearranges the nanographene stacking structure to produce ultramicropores that can be accessible only for Ar. TEM, X-ray diffraction, and Raman spectroscopic studies indicated that the compression for 25 h unfolds double-bent-like structures, relaxing the unstable nanographene stacked structure formed on the initial compression without nanographene sheets collapse. This behavior stems from the highly elastic nature of the nanographenes.

The detonation nanodiamonds form the aggregate having interparticle voids, giving a marked hygroscopic property. As the relationship between pore structure and water adsorption of aggregated nanodiamonds is not well understood yet, adsorption isotherms of N 2 at 77 K and of water vapor at 298 K of the well-characterized aggregated nanodiamonds were measured. HR-TEM and X-ray diffraction showed that the nanodiamonds were highly crystalline and their average crystallite size was 4.5 nm. The presence of the graphitic layers on the nanodiamond particle surface was confirmed by the EELS examination. The pore size distribution analysis showed that nanodiamonds had a few ultramicropores with predominant mesopores of 4.5 nm in average size. The water vapor adsorption isotherm of IUPAC Type V indicates the hydrophobicity of the nanodiamond aggregates, with the presence of hydrophilic sites. Then the hygroscopic nature of nanodiamonds should be associated with the surface functionalities of the graphitic shell and the ultramicropores on the mesopore walls.

Thus far, nobody has successfully obtained the accurate information on the properties of the adsorbed phases of gases or vapors formed inside a cylindrical micropore of single-walled carbon nanotube (SWCNT) itself based on the experimental procedure. In this work, we succeeded in analyzing experimentally the properties of adsorbed nitrogen and water confined in the inner pore of SWCNT itself by opening the pore composed of close-ended SWCNT without any changes in the surface state and also by applying the unique method for characterization; both the amounts, as well as properties, of surface functional groups and the bundle structure are the same even after the treatments for introducing an open-ended structure to a close-ended one. As a result, the average pore sizes, as well as characteristic adsorption behavior, on the two types of sample were available from the analysis of respective difference adsorption isotherms of nitrogen measured at 77 K between the adsorbed amounts on the open-ended SWCNT and that on the close-ended one. The evaluated pore sizes well coincide with the results estimated by Raman data. These results strongly support that we could analyze the adsorbed phases formed only in the inner pore of SWCNTs by applying the present method. Furthermore, we could analyze the adsorbed phase of water formed inside the cylindrical micropore of SWCNTs, showing the difference in the densities of adsorbed water depending on the pore sizes from the value of bulk water; the densities of the adsorbed water were evaluated to be 0.62 and 0.71 g mL(-1) for SWCNTs having average pore sizes of 1.3 and 1.7 nm, respectively, which were in harmony with those obtained by the theoretical calculations reported by other researchers. The proposed analysis method makes it possible to recognize the focused states of the adsorbed water formed inside the cylindrical micropore of SWCNT more precisely and correctly. The method proposed will shed light on the discussion related to the detailed nature of various adsorbed gases into SWCNT, to the detailed role of adsorbed species formed inside pore in various phenomena, and to the designing the useful materials based on the gained knowledge.