Electrochemical phase transformation accompanied with Mg extraction and insertion in a spinel MgMn2O4 cathode material.

One of the key challenges when developing magnesium rechargeable batteries (MRB) is to develop Mg-intercalation cathodes exhibiting higher redox potentials with larger specific capacities. Although Mg-transition-metal spinel oxides have been shown to be excellent candidates as MRB cathode materials by utilizing the valence change from trivalent to divalent of transition metals starting from Mg insertion, there is no clear evidence to date that Mg can be indeed extracted from the initial spinel hosts by utilizing the change from trivalent to quadrivalent. In this work, we clearly present various experimental evidences of the electrochemical extraction of Mg from spinel MgMn2O4. The present electrochemical charge, i.e., extraction treatment of Mg, was performed in an ionic liquid at 150 °C to ensure Mg hopping in the spinel host. Our analyses show that Mg can be extracted from Mg1-xMn2O4 up to x = 0.4 and, afterwards, successively be inserted into the Mg-extracted (demagnesiated) host via a two-phase reaction between tetragonal and cubic spinels. Finally, we also discuss the difference in electrochemical features between LiMn2O4 and MgMn2O4.

Introduction of arteriovenous grafts with graft insertion anastomosis for hemodialysis access.

OBJECTIVE: An arteriovenous bridging graft is a viable option for patients with compromised arteries or veins because of advanced age or diabetes. Arteriovenous graft with graft insertion anastomosis (AVGI) is the novel technique for graft-vein anastomosis where the prosthesis is inserted into the vein, and the anastomosis is performed on the surface of the prosthesis. This study assessed the short-term and long-term results of AVGI to clarify the efficacy of this technique. METHODS: Between 2010 and 2015, AVGI was performed in graft-vein anastomosis of prosthetic forearm loop access. Characteristics and level of complications were assessed. To evaluate the long-term results, functional graft patency and frequency of percutaneous transluminal angioplasty were examined. RESULTS: The study comprised 58 patients. There were no deaths related to the surgery. The time of hemostasis after AVGI was recorded at 0 seconds because no bleeding from the suture holes was seen. At 1, 2, and 3 years, primary patency were 45.1% ± 7.5%, 23.1% ± 7.5%, and 23.1% ± 7.5%, respectively, and assisted primary patency rates were 59.4% ± 7.2%, 50.8% ± 7.6%, and 50.8% ± 7.6%, respectively. Secondary patency rates at 4 and 5 years were 100% ± 0% and 94.1% ± 5.7%, respectively. The frequency of percutaneous balloon angioplasty to maintain the patency was 1.61 ± 0.53 times per year. Graft infection occurred in four patients (6.9%). CONCLUSIONS: AVGI is an advantageous technique for graft vein anastomosis in an arteriovenous bridging graft in both the short-term and long-term.

Examining Electrolyte Compatibility on Polymorphic MnO2 Cathodes for Room-Temperature Rechargeable Magnesium Batteries.

Rechargeable magnesium batteries are promising candidates for post-lithium-ion batteries, owing to the large source abundance and high theoretical energy density. However, there remain few reports on constructing practical cells with oxide cathodes and Mg anodes at room temperature. In this work, we compare the reaction behavior of various MnO2 polymorph cathodes in two representative electrolytes: Mg[TFSA]2/G3 and Mg[Al(hfip)4]2/G3. In Mg[TFSA]2/G3, discharge capacities of the MnO2 cathodes are well consistent with the changes in Mg composition, where nanorod-like α-MnO2 and λ-MnO2 show the capacities of about 100 mA h g-1 at room temperature. However, this electrolyte has the disadvantage that the Mg anodes are easily passivated. In contrast, Mg[Al(hfip)4]2/G3 allows highly reversible deposition/dissolution of Mg anodes, whereas the discharge process of the MnO2 cathodes involves a large part of side reactions, in which the MnO2 active material takes part in some reductive reaction together with electrolyte species instead of the expected Mg2+ intercalation. Such an unstable electrode/electrolyte interface would lead to continuous degradation on/near the cathode surface. Thus, the interfacial stability between the oxide cathodes and the electrolytes must be improved for practical applications.

Excellently balanced water-intercalation-type heat-storage oxide.

Importance of heat storage materials has recently been increasing. Although various types of heat storage materials have been reported to date, there are few well-balanced energy storage materials in terms of long lifetime, reversibility, energy density, reasonably fast charge/discharge capability, and treatability. Here we report an interesting discovery that a commonly known substance, birnessite-type layered manganese dioxide with crystal water (δ-type K0.33MnO2 ⋅ nH2O), exhibits a water-intercalation mechanism and can be an excellently balanced heat storage material, from the above views, that can be operated in a solid state with water as a working pair. The volumetric energy density exceeds 1000 MJ m-3 (at n ~ 0.5), which is close to the ideally maximum value and the best among phase-change materials. The driving force for the water intercalation is also validated by the ab initio calculations. The proposed mechanism would provide an optimal solution for a heat-storage strategy towards low-grade waste-heat applications.

Endothelial nitric oxide synthase regulates microvascular hyperpermeability in vivo.

Nitric oxide (NO) is an important regulator of blood flow, but its role in permeability is still challenged. We tested in vivo the hypotheses that: (a) endothelial nitric oxide synthase (eNOS) is not essential for regulation of baseline permeability; (b) eNOS is essential for hyperpermeability responses in inflammation; and (c) molecular inhibition of eNOS with caveolin-1 scaffolding domain (AP-Cav) reduces eNOS-regulated hyperpermeability. We used eNOS-deficient (eNOS-/-) mice and their wild-type control as experimental animals, platelet-activating factor (PAF) at 10(-7) m as the test pro-inflammatory agent, and integrated optical intensity (IOI) as an index of microvascular permeability. PAF increased permeability in wild-type cremaster muscle from a baseline of 2.4 +/- 2.2 to a peak net value of 84.4 +/- 2.7 units, while the corresponding values in cremaster muscle of eNOS-/- mice were 1.0 +/- 0.3 and 15.6 +/- 7.7 units (P < 0.05). Similarly, PAF increased IOI in the mesentery of wild-type mice but much less in the mesentery of eNOS-/- mice. PAF increased IOI to comparable values in the mesenteries of wild-type mice and those lacking the gene for inducible NOS (iNOS). Administration of AP-Cav blocked the microvascular hyperpermeability responses to 10(-7) m PAF. We conclude that: (1) baseline permeability does not depend on eNOS; (2) eNOS and NO are integral elements of the signalling pathway for the hyperpermeability response to PAF; (3) iNOS does not affect either baseline permeability or hyperpermeability responses to PAF; and (4) caveolin-1 inhibits eNOS regulation of microvascular permeability in vivo. Our results establish eNOS as an important regulator of microvascular permeability in inflammation.

Mitogen-activated protein kinases regulate platelet-activating factor-induced hyperpermeability.

OBJECTIVE: The authors tested the hypothesis that p42/44- (ERK-1/2) and/or p38-mitogen-activated protein kinases (MAPK) are in vivo regulatory elements in the platelet-activating factor (PAF) activated signaling cascade that stimulates microvascular hyperpermeability. METHODS: FITC-dextran 70 was used as the macromolecular tracer for microvascular permeability in the mouse mesenteric fat tissue. Interstitial integrated optical intensity (IOI) was used as an index of permeability. RESULTS: An application of 10(-7) M PAF increased IOI from 23.1 +/- 3.6 to 70.8 +/- 7.4 (mean +/- SEM). Inhibition of ERK-1/2 with 3 microM and 30 microM AG126 reduced IOI to 32.3 +/- 2.5. Similarly, inhibition of p38-MAPK with 6 nM, 60 nM and 600 nM SB203580 lowered IOI to 29.1 +/- 2.4. CONCLUSIONS: The results demonstrate that ERK-1/2 and p38MAPK participate in the signaling cascade that regulates PAF-induced microvascular hyperpermeability in vivo.