In situ neutron imaging of lithium-ion batteries during heating to thermal runaway.

Lithium-ion batteries (LIBs) have become essential components that power most current technologies, such as smartphones and electric vehicles, thus making various safety evaluations necessary to ensure their safe use. Among these evaluations, heating tests remain the most prominent source of safety issues. However, information on the phenomena occurring inside batteries during heating has remained inaccessible. In this study, we demonstrate the first in situ neutron imaging method to observe the internal structural deformation of LIBs during heating. We developed an airtight aluminium chamber specially designed to prevent radioactive contamination during in situ neutron imaging. We successfully observed the liquid electrolyte fluctuation inside a battery sample and the deformation of the protective plastic film upon heating up to thermal runaway. Hence, this work provides the foundation for future investigations of the internal changes induced in batteries during heating tests and experiments.

Assessment of skin inflammation using near-infrared Raman spectroscopy combined with artificial intelligence analysis in an animal model.

Raman spectroscopy is a powerful method for estimating the molecular structure of a target that can be adapted for biomedical analysis given its non-destructive nature. Inflammatory skin diseases impair the skin's barrier function and interfere with the patient's quality of life. There are limited methods for non-invasive and objective assessment of skin inflammation. We examined whether Raman spectroscopy can be used to predict skin inflammation with high sensitivity and specificity when combined with artificial intelligence (AI) analysis. Inflammation was chemically induced in mouse ears, and Raman spectra induced by a 785 nm laser were recorded. A principal component (PC) analysis of the Raman spectra was performed to extract PCs with the highest percentage of variance and to estimate the statistical score. The accuracy in predicting inflammation based on the Raman spectra with or without AI analysis was assessed using receiver operating characteristic (ROC) curves. We observed some typical changes in the Raman spectra upon skin inflammation, which may have resulted from vasodilation and interstitial oedema. The estimated statistical scores based on spectral changes correlated with the histopathological changes in the skin. The ROC curve based on PC2, which appeared to include some spectral features, revealed a maximum accuracy rate of 80.0% with an area under the curve (AUC) of 0.864. The AI analysis improved the accuracy rate to 93.1% with an AUC of 0.972. The current findings demonstrate that the combination of Raman spectroscopy with near-infrared excitation and AI analysis can provide highly accurate information on the pathology of skin inflammation.

Leakage of Endotoxins through the Endotoxin Retentive Filter: An in vitro Study.

INTRODUCTION: Ultrapurification of dialysis fluid has enabled highly efficient dialysis treatments. Online hemodiafiltration is one such treatment that uses a purified dialysis fluid as a supplemental fluid. In this method, an endotoxin retentive filter (ETRF) is used in the final step of dialysis fluid purification, with the aim of preventing leakage of endotoxins. Sodium hypochlorite and peracetic acid are used as disinfecting agents for the dialysis fluid pipes containing the ETRF; however, the effects of these agents on ETRF membrane pores have not been fully clarified. METHODS: Water permeability (flux) and endotoxin permeability were assessed in 3 types of ETRFs made with different membrane materials: polyester polymer alloy (PEPA), polyether sulfone (PES), and polysulfone (PS). High-concentration sodium hypochlorite and 2 types of peracetic acid were used as disinfecting agents, and the changes in flux and the endotoxin sieving coefficient (SC) were measured. RESULTS: After repeated use of high concentrations of sodium hypochlorite and peracetic acid, the PEPA and PES ETRFs did not permit passage of endotoxins, regardless of their flux. However, in the PS ETRF, the flux and endotoxin SC increased with the number of cleaning cycles. No differences were observed according to the concentration of peracetic acid disinfecting agents. CONCLUSION: PEPA and PES ETRFs completely prevent endotoxin leakage and can be disinfected at concentrations higher than the conventionally recommended concentration without affecting pore expansion. Even new PS ETRFs have low levels of endotoxin leakage, which increase after disinfection cycles using sodium hypochlorite and peracetic acid.

Low-Resistance Mechanism of Nanoflake Crystalline Aromatic Dicarboxylates with Selective Defects for Safe and Fast Charging Negative Electrodes.

Low resistance of Li-intercalated negative electrodes is important for the safe and fast charging required for large-scale batteries. Here, we demonstrated that nanosized two-dimensional crystalline aromatic dicarboxylate negative electrode materials synthesized via spray drying exhibit low internal resistances at approximately 0.7 V vs Li/Li+, while retaining flat potential profiles. The spray-dried sample with a hollow structure is crushed into nanoflakes during ink preparation for electrode coating and forms a uniform and highly dispersed electrode structure. The charge-discharge evaluation indicates that the nanoflake sample showed smaller charge-discharge polarization than the bulk sample with stable cycling characteristics, resulting in significant high-rate property enhancement. Charge-transfer resistance of the nanoflake sample exhibits the lowest value (ca. 2.2 Ω cm2) among those reported for existing intercalation electrodes (5.2 to 235 Ω cm2). In comparison of the negative electrodes, the estimated maximum current density without Li deposition (ca. 316 mA cm-2) is more than 1 order of magnitude higher than that for currently used graphite (ca. 11 mA cm-2) and is also higher than those for high-rate oxides (137-298 mA cm-2). The resistance-crystal correlation using multiple regression analysis predictions and its verification reveal that this low resistance is owing to an improved Li acceptability associated with selective structural defects induced by the loss of incorporated crystallized water during drying. The crystal plane exposed by the selective structural defects is perpendicular to electronic and ionic conduction directions inside the solid, resulting in improved kinetics. Therefore, the proposed negative electrode allows safe and fast charging, with easy scale-up and sustainable resources.

Lithium-ion attack on yttrium oxide in the presence of copper powder during Li plating in a super-concentrated electrolyte.

Li plating/stripping on Cu and Y2O3 (Cu + Y2O3) electrodes was examined in a super-concentrated electrolyte of lithium bis(fluorosulfonyl)amide and methylphenylamino-di(trifluoroethyl) phosphate. In principle, Li+ ions cannot intercalate into a Y2O3 crystal because its intercalation potential obtained from first-principles calculations is -1.02 V vs. Li+/Li. However, a drastic decrease in the electrode potential and a subsequent constant-potential region were observed during Li plating onto a Cu + Y2O3 electrode, suggesting that Li+ interacted with Y2O3. X-ray diffraction (XRD) patterns and X-ray absorption fine structure (XAFS) spectra of the Cu + Y2O3 electrodes after the Li plating were recorded to verify this phenomenon. The XRD and XAFS results indicated that the crystallinity of Y2O3 crystals was lowered because of attack by Li+ ions or that the Y2O3 crystal structure was broken while the +3 valence state of Y was maintained.

Observation of lithium stripping in super-concentrated electrolyte at potentials lower than regular Li stripping.

Lithium plating/stripping was investigated under constant current mode using a copper powder electrode in a super-concentrated electrolyte of lithium bis(fluorosulfonyl)amide (LiFSA) with methylphenylamino-di(trifluoroethyl) phosphate (PNMePh) and vinylene carbonate (VC) as additives. Typical Li plating/stripping for Cu electrodes in organic electrolytes of conventional lithium batteries proceeds at potentials of several millivolts versus a Li counter electrode. In contrast, a large overpotential of hundreds of millivolts was observed for Li plating/stripping with the super-concentrated electrolyte. When Li stripping started immediately after Li plating and with no rest time between plating and stripping, two potential plateaus, i.e., two-step Li stripping, was observed. The potential plateau for the 1st stripping step appeared at -0.2 V versus a Li metal counter electrode. The electrical capacity for the 1st stripping step was 0.04 mA h cm-2, which indicates irregular Li stripping. Two-step Li stripping was also recorded using cyclic voltammetry. The electrochemical impedance spectroscopy (EIS) studies indicated that the two-step Li stripping behaviour reflected two different solid electrolyte interphases (SEIs) on electrodeposited Li in a Cu electrode. The SEI for the 1st-step stripping was in a transition period of the SEI formation. The open circuit voltage (OCV) relaxation with an order of tens of hours was detected after Li plating and before Li stripping. The in operando EIS study suggested a decrease of the charge transfer resistance in the Cu powder electrode during the OCV relaxation. Since the capacitance for the voltage relaxation was a dozen microfarads, it had a slight contribution to the 1st-step Li stripping behaviour. The voltage relaxation indicated the possibility that it is difficult for Li ions to be electrodeposited or that the Li plating is in a quasi-stable state.

Magnetic phase diagram of K2Cr8O16 clarified by high-pressure muon spin spectroscopy.

The K2Cr8O16 compound belongs to a series of quasi-1D compounds with intriguing magnetic properties that are stabilized through a high-pressure synthesis technique. In this study, a muon spin rotation, relaxation and resonance (µ+SR) technique is used to investigate the pressure dependent magnetic properties up to 25 kbar. µ+SR allows for measurements in true zero applied field and hereby access the true intrinsic material properties. As a result, a refined temperature/pressure phase diagram is presented revealing a novel low temperature/high pressure (pC1 = 21 kbar) transition from a ferromagnetic insulating to a high-pressure antiferromagnetic insulator. Finally, the current study also indicates the possible presence of a quantum critical point at pC2 ~ 33 kbar where the magnetic order in K2Cr8O16 is expected to be fully suppressed even at T = 0 K.

Nuclear Magnetic Field in Solids Detected with Negative-Muon Spin Rotation and Relaxation.

Using an intense negative muon (µ^{-}) source, we have studied the internal magnetic fields in a powder sample of magnesium hydride (MgH_{2}). By extracting the signal from the µ^{-} captured on Mg nuclei, we found that the negative muon spin rotation and relaxation (µ^{-}SR) spectra clearly showed a Kubo-Toyabe-type relaxation, which indicates a random magnetic field at the Mg site. The field distribution width obtained is very consistent with the predicted value at the Mg site estimated by dipole field calculations, supporting our claim to have observed the nuclear magnetic fields of hydrogens in MgH_{2}. As is the case with µ^{+}SR, µ^{-}SR promises to soon be an indispensable tool for materials analyses.

Li-ion diffusion in Li intercalated graphite C6Li and C12Li probed by µ+SR.

In order to study a diffusive behavior of Li+ in Li intercalated graphites, we have measured muon spin relaxation (µ+SR) spectra for C6Li and C12Li synthesized with an electrochemical reaction between Li and graphite in a Li-ion battery. For both compounds, it was found that Li+ ions start to diffuse above 230 K and the diffusive behavior obeys a thermal activation process. The activation energy (Ea) for C6Li is obtained as 270(5) meV, while Ea = 170(20) meV for C12Li. Assuming a jump diffusion of Li+ in the Li layer of C6Li and C12Li, a self-diffusion coefficient DLi at 310 K was estimated as 7.6(3) × 10-11 (cm2 s-1) in C6Li and 14.6(4) × 10-11 (cm2 s-1) in C12Li.

HpDTC1, a Stress-Inducible Bifunctional Diterpene Cyclase Involved in Momilactone Biosynthesis, Functions in Chemical Defence in the Moss Hypnum plumaeforme.

Momilactones, which are diterpenoid phytoalexins with antimicrobial and allelopathic functions, have been found only in rice and the moss Hypnum plumaeforme. Although these two evolutionarily distinct plant species are thought to produce momilactones as a chemical defence, the momilactone biosynthetic pathway in H. plumaeforme has been unclear. Here, we identified a gene encoding syn-pimara-7,15-diene synthase (HpDTC1) responsible for the first step of momilactone biosynthesis in the moss. HpDTC1 is a bifunctional diterpene cyclase that catalyses a two-step cyclization reaction of geranylgeranyl diphosphate to syn-pimara-7,15-diene. HpDTC1 transcription was up-regulated in response to abiotic and biotic stress treatments. HpDTC1 promoter-GUS analysis in transgenic Physcomitrella patens showed similar transcriptional responses as H. plumaeforme to the stresses, suggesting that a common response system to stress exists in mosses. Jasmonic acid (JA), a potent signalling molecule for inducing plant defences, could not activate HpDTC1 expression. In contrast, 12-oxo-phytodienoic acid, an oxylipin precursor of JA in vascular plants, enhanced HpDTC1 expression and momilactone accumulation, implying that as-yet-unknown oxylipins could regulate momilactone biosynthesis in H. plumaeforme. These results demonstrate the existence of an evolutionarily conserved chemical defence system utilizing momilactones and suggest the molecular basis of the regulation for inductive production of momilactones in H. plumaeforme.

Discovery of a Novel Diterpene in Brown Propolis from the State of Parana, Brazil.

Propolis is a resinous substance collected by honeybees from certain plant sources. The components of propolis depend on the vegetation of the area in which apiculture is practiced. In Brazil, there are several types of propolis including 'green,' 'red' and 'brown'. Brazilian brown propolis from the state of Parana characteristically includes diterpenes, and we discovered a novel clerodane diterpene, rel-(5S,6S,8R,9R,10S,18R,19S)-18,19-epoxy-2-oxocleroda-3,12(E),14- triene-6,18,19-triol 18,19-diacetate 6-benzoate (3) and five known diterpenes (1, 2, 4, 5 and 6). The chemical structure of the novel diterpene 3 was determined using 1D- and 2D-NMR spectroscopic analyses. Furthermore, the activities of the isolated diterpenes on growth inhibition of several human cancer cell lines (LNCaP, MCF-7, DLD-1 and A549) were evaluated in vitro; diterpene 3 exhibited a potent inhibition of cell growth, and its activity was approximately 15 times higher than that of the other diterpenes.

Development of 4-methoxy-7-nitroindolinyl (MNI)-caged auxins which are extremely stable in planta.

Phytohormone auxin is a master regulator in plant growth and development. Regulation of cellular auxin level plays a central role in plant development. Auxin polar transport system modulates an auxin gradient that determines plant developmental process in response to environmental conditions and developmental programs. Photolabile caged auxins allow optical control of artificial auxin gradients at cellular resolution. Especially, two-photon uncaging system achieves high spatiotemporal control of photolysis reaction at two-photon cross-section. However, the development of caged versions of auxin has been limited by the instability of the caged auxins to higher plant metabolic activities. Here, we describe the synthesis and application of highly stable caged auxins, 4-methoxy-7-nitroindolinyl (MNI)-caged auxins. Natural auxin, indole 3-acetic acid, and two synthetic auxins, 1-NAA and 2,4-D were caged by MNI caging group. MNI-caged auxins showed a high stability in planta and a rapid release the original auxin when photolyzed. We demonstrated that optical control of auxin-responsive gene expression and auxin-related physiological responses by using MNI-caged auxins. We anticipate that MNI-caged auxins will be an effective tool for high-resolution control of endogenous auxin level.

Cassane-type diterpenoids from Caesalpinia echinata (Leguminosae) and their NF-κB signaling inhibition activities.

Fourteen cassane-type diterpenoids, echinalides H-U, were isolated from the stem of Caesalpinia echinata Lam. (Leguminosae). The structures of the echinalides were elucidated by spectroscopic investigation, including 2D NMR spectroscopic analysis. The structures of echinalide H and echinalide T were further confirmed by single-crystal X-ray diffraction. The absolute configurations of echinalides H, I, J and K were determined by CD spectroscopy. Additionally, the absolute configurations of echinalide L and M were determined by chemical conversion from echinalide H. These compounds were evaluated for inhibitory activity against nuclear factor κB (NF-κB). Echinalide M showed the most potent inhibitory activity (47±11% at 5µM) toward NF-κB-responsive gene expression.

Molecular evolution of the substrate specificity of ent-kaurene synthases to adapt to gibberellin biosynthesis in land plants.

ent-Kaurene is a key intermediate in the biosynthesis of the plant hormone gibberellin. In ent-kaurene biosynthesis in flowering plants, two diterpene cyclases (DTCs), ent-copalyl diphosphate (ent-CDP) synthase (ent-CPS) and ent-kaurene synthase (KS), catalyse the cyclization of geranylgeranyl diphosphate to ent-CDP and ent-CDP to ent-kaurene, respectively. In contrast, the moss Physcomitrella patens has a bifunctional ent-CPS/KS (PpCPS/KS) that catalyses both cyclization reactions. To gain more insight into the functional diversity of ent-kaurene biosynthetic enzymes in land plants, we focused on DTCs in the lycophyte Selaginella moellendorffii. The present paper describes the characterization of two S. moellendorffii DTCs (SmKS and SmDTC3) in vitro. SmDTC3 converted ent-CDP into ent-16α-hydroxykaurane and also used other CDP stereoisomers as substrate. Remarkably, SmKS, which produces ent-kaurene from ent-CDP, showed similar substrate selectivity: both SmKS and SmDTC3 synthesized sandaracopimaradiene from normal CDP. Therefore, the diversity of substrate recognition among KSs from other plants was investigated. PpCPS/KS could use normal CDP and syn-CDP as well as ent-CDP as substrate. In contrast, lettuce KS showed high specificity for ent-CDP, and rice KS recognized only ent-CDP. Our studies imply that ancient KS having low substrate specificity has evolved to be specific for ent-CDP to the biosynthesis of gibberellin.

Auxin transport sites are visualized in planta using fluorescent auxin analogs.

The plant hormone auxin is a key morphogenetic signal that controls many aspects of plant growth and development. Cellular auxin levels are coordinately regulated by multiple processes, including auxin biosynthesis and the polar transport and metabolic pathways. The auxin concentration gradient determines plant organ positioning and growth responses to environmental cues. Auxin transport systems play crucial roles in the spatiotemporal regulation of the auxin gradient. This auxin gradient has been analyzed using SCF-type E3 ubiquitin-ligase complex-based auxin biosensors in synthetic auxin-responsive reporter lines. However, the contributions of auxin biosynthesis and metabolism to the auxin gradient have been largely elusive. Additionally, the available information on subcellular auxin localization is still limited. Here we designed fluorescently labeled auxin analogs that remain active for auxin transport but are inactive for auxin signaling and metabolism. Fluorescent auxin analogs enable the selective visualization of the distribution of auxin by the auxin transport system. Together with auxin biosynthesis inhibitors and an auxin biosensor, these analogs indicated a substantial contribution of local auxin biosynthesis to the formation of auxin maxima at the root apex. Moreover, fluorescent auxin analogs mainly localized to the endoplasmic reticulum in cultured cells and roots, implying the presence of a subcellular auxin gradient in the cells. Our work not only provides a useful tool for the plant chemical biology field but also demonstrates a new strategy for imaging the distribution of small-molecule hormones.

New cassane-type diterpenoids of Caesalpinia echinata (Leguminosae) exhibiting NF-κB inhibitory activities.

Seven new cassane-type diterpenoids, echinalides A-G (1-7), were isolated from the stem of Caesalpinia echinata LAM. (Leguminosae). The structures were established on the basis of their chemical properties and spectroscopic evidence, including two dimensional (2D)-NMR analysis. These compounds were assessed for inhibitory activity against nuclear factor κB (NF-κB). Echinalides C and D, in particular, significantly inhibited NF-κB-responsive reporter gene expression at 5.0 µM, an effect almost equivalent to that of parthenolide, a known potent inhibitor of NF-κB.

Culcitiolides E-J, six new eremophilane-type sesquiterpene derivatives from Senecio culcitioides.

Culcitiolides E-J (1-6), six new eremophilane-type sesquiterpenes, were isolated from the stem of Senecio culcitioides SCH. BIP. (Asteraceae). The structures were determined by detailed NMR spectral analysis. The inhibitory activities of these compounds against nuclear factor κB (NF-κB)-dependent gene expression were assessed. Culcitiolides E, H, and I potently inhibited NF-κB-induced gene expression at 20 µM.

Magnetic structure of the metallic triangular antiferromagnet Ag2NiO2.

The magnetic structure of the metallic antiferromagnet Ag2NiO2 with the Néel temperature TN = 56 K has been investigated by means of a neutron diffraction technique using a powder sample in the temperature range between 5 and 65 K. The antiferromagnetic (AF) diffraction peaks are clearly observed below TN and can be indexed with the propagation vector [Formula: see text]. Based on the results of both a representational analysis and a Rietveld refinement of the magnetic peaks, the AF spin structure is determined as an A-type AF structure with ml = m0cos(2πk ⋅l), where ml is the moment at the lth Ni(3+) site and m0 = (0.31,0,0.65) µB at 5 K.

Reactive surface area of the Li(x)(Co(1/3)Ni(1/3)Mn(1/3))O2 electrode determined by µ(+)SR and electrochemical measurements.

The self-diffusion coefficient of Li(+) ions (D(Li)) in the positive electrode material Li(x)(Co(1/3)Ni(1/3)Mn(1/3))O2 has been estimated by muon-spin relaxation (µ(+)SR) using powder samples with x = 1-0.49, which were prepared by an electrochemical reaction in a Li-ion battery. Here, since the implanted muons sense a slight change in the internal magnetic field due to Li-diffusion, µ(+)SR provides an intrinsic D(Li) through the temperature dependence of the nuclear field fluctuation rate (ν) [Sugiyama et al., Phys. Rev. Lett., 2009, 103, 147601]. Both D(Li) at 300 K and activation energy (E(a)) were estimated to be ∼2.9 × 10(-12) cm(2) s(-1) and 0.074 eV for the x = 1 sample, ∼11.0 × 10(-12) cm(2) s(-1) and 0.097 eV for x = 0.70, and ∼8.9 × 10(-12) cm(2) s(-1) and 0.062 eV for x = 0.49, assuming that the diffusing Li(+) ions mainly jump from a regular occupied site to a regular vacant site. The estimated D(Li) was smaller by roughly one order of magnitude than those for Li(x)CoO2 in the whole x range measured. Furthermore, by making comparison with D(Li) obtained by electrochemical measurements, the reactive surface area of the Li(x)(Co(1/3)Ni(1/3)Mn(1/3))O2 electrode in a liquid electrolyte was found to strongly depend on x particularly at x > 0.8.

Design and synthesis of photolabile caged cytokinin.

Cytokinins are phytohormones that regulate diverse developmental processes throughout the life of a plant. trans-Zeatin, kinetin, benzyladenine and dihydrozeatin are adenine-type cytokinins that are perceived by the AHK cytokinin receptors. Endogenous cytokinin levels are critical for regulating plant development. To manipulate intracellular cytokinin levels, caged cytokinins were designed on the basis of the crystal structure of the AHK4 cytokinin receptor. The caged cytokinin was photolyzed to release the cytokinin molecule inside the cells and induce cytokinin-responsive gene expression. The uncaging of intracellular caged cytokinins demonstrated that cytokinin-induced root growth inhibition can be manipulated with photo-irradiation. This caged cytokinin system could be a powerful tool for cytokinin biology.