Tailored surface structure of LiFePO4/C nanofibers by phosphidation and their electrochemical superiority for lithium rechargeable batteries.

We offer a brand new strategy for enhancing Li ion transport at the surface of LiFePO4/C nanofibers through noble Li ion conducting pathways built along reduced carbon webs by phosphorus. Pristine LiFePO4/C nanofibers composed of 1-dimensional (1D) LiFePO4 nanofibers with thick carbon coating layers on the surfaces of the nanofibers were prepared by the electrospinning technique. These dense and thick carbon layers prevented not only electrolyte penetration into the inner LiFePO4 nanofibers but also facile Li ion transport at the electrode/electrolyte interface. In contrast, the existing strong interactions between the carbon and oxygen atoms on the surface of the pristine LiFePO4/C nanofibers were weakened or partly broken by the adhesion of phosphorus, thereby improving Li ion migration through the thick carbon layers on the surfaces of the LiFePO4 nanofibers. As a result, the phosphidated LiFePO4/C nanofibers have a higher initial discharge capacity and a greatly improved rate capability when compared with pristine LiFePO4/C nanofibers. Our findings of high Li ion transport induced by phosphidation can be widely applied to other carbon-coated electrode materials.

A nano-Si/FeSi2Ti hetero-structure with structural stability for highly reversible lithium storage.

A nano-Si/FeSi2Ti hetero-structure has been synthesized for highly reversible Li-ion batteries by using a simple melt-spinning method. We demonstrate that this composite has a very peculiar core/shell structure in which the FeSi2Ti alloy plays various pivotal roles as a mechanically supporting backbone and as an electronic pathway for the active Si attached to its surface, and is responsible for the altered electrochemical reactions with relatively small volume expansion routes. The FeSi2Ti matrix significantly contributes to not only the stabilization of cyclic retention, but also the enhancement of conductivity, as well as a high rate capability unprecedented in research on Si-based anodes. This achievement demonstrates the potency of this novel hybrid design for electrode materials for energy storage.

α-MnO2 nanowire catalysts with ultra-high capacity and extremely low overpotential in lithium-air batteries through tailored surface arrangement.

We here report on very high capacity (11,000 mA h g(-1)), superb rate capability (4500 mA h g(-1) at 5000 mA g(-1)) and high reversibility of Li-air batteries using α-MnO2 NW catalysts mainly associated with their relatively large amount of Mn(3+) exposed on the NW surface and a unique mechanism for deposition of discharge products. Our findings of the unprecedentedly fast Li ion transport and reversible formation-decomposition of discharge products attributed to the modified surface arrangement of α-MnO2 NWs suggest a strategy for achieving high-power Li-air batteries in combination with nano-architecture tailoring.

Structurally and electronically designed TiO2Nx nanofibers for lithium rechargeable batteries.

The morphology and electronic structure of metal oxides, including TiO(2) on the nanoscale, definitely determine their electronic or electrochemical properties, especially those relevant to application in energy devices. For this purpose, a concept for controlling the morphology and electrical conductivity in TiO(2), based on tuning by electrospinning, is proposed. We found that the 1D TiO(2) nanofibers surprisingly gave higher cyclic retention than 0D nanopowder, and nitrogen doping in the form of TiO(2)N(x) also caused further improvement. This is due to higher conductivity and faster Li(+) diffusion, as confirmed by electrochemical impedance spectra. Our findings provide an effective and scalable solution for energy storage efficiency.

Airways are more reactive to histamine than to methacholine in patients with mild airway hyperresponsiveness, regardless of atopy.

BACKGROUND: The airway muscles from allergen-sensitized animals in vitro show a heightened response to histamine, but not to carbachol. This study investigated whether the airway responsiveness to histamine in vivo is comparable to that of methacholine in human subjects with varying degrees of atopy. METHODS: One-hundred-and-sixty-eight consecutive adult asthma patients or volunteers underwent bronchoprovocation tests to both histamine and methacholine after determining their blood eosinophil counts, serum total IgE levels and skin test reactivity to 10 common aeroallergens. RESULTS: The responsiveness to histamine was significantly related to that to methacholine (r=0.609, p<0.001), but many individuals with a negative methacholine test response showed a positive response to histamine. The histamine-bronchial reactivity index (BRindex) was significantly higher than the methacholine-BRindex in subjects with a positive response to none (n=69, p<0.01) or only one (n=42, p<0.001) of histamine and methacholine, while there was no significant difference in the subjects with positive responses to both of them (n=57). The histamine-BRindex was significantly higher than the methacholine-BRindex in the subjects with mild histamine hyperresponsiveness (n=58, 1.28+/-0.01 vs. 1.20+/-0.02, respectively, p<0.001). Both histamine and methacholine responsiveness was significantly related to the atopy markers. However, the histamine-BRindex/methacholine-BRindex ratio of the atopics was not significantly different from that of the non-atopics. CONCLUSIONS: The airway responsiveness to histamine is comparable to that of methacholine in the subjects with positive responses to both histamine and methacholine, but the airway responsiveness to histamine is greater than that to methacholine in those subjects with mild airway hyperresponsiveness, regardless of atopy.

Effects of anti-asthma therapy on dyspnea perception in acute asthma patients.

Blunted perception of dyspnea may predispose patients to fatal asthma attacks. To examine whether this impaired perception of dyspnea in patients with acute asthma could be corrected by anti-asthma therapy, the medical records of 104 consecutive asthma patients who had been hospitalized as a result of asthma attacks were analyzed retrospectively. During the course of treatment with conventional asthma medications, the forced expiratory volume in 1s (FEV1) and the Borg scale-based dyspnea perception scores during breathing through an inspiratory muscle trainer were measured at least twice. The baseline Borg score measured just before discharge was significantly lower than from that measured initially, regardless of improvement in FEV1. In contrast, the Borg score at the highest resistance (HR; 3.12+/-0.26 vs. 5.03+/-0.53; P<0.01) and the HR-induced DeltaBorg score (1.68+/-0.20 vs. 4.47+/-0.54, P<0.001) were increased significantly in the Poor Perceivers (Borg score 5 at HR and HR-induced DeltaBorg score 3). Patient age (r=0.363, P<0.001), blood eosinophil counts (r=-0.285, P<0.01), and serum total IgE levels (r=-0.213, P<0.05), but not FEV1, were significantly related to the effect of the treatment on the HR-induced DeltaBorg scores. These findings suggest that anti-asthma treatments decrease dyspnea even without a concomitant improvement in lung function and correct the impaired perception of inspiratory resistive load in acute asthma, and that age and allergy influence the effect of treatment on impaired perception.