A nitroxide-containing cathode material for organic radical batteries studied with pulsed EPR spectroscopy

An electron spin echo in a nitroxide-containing polymer cathode film for organic radical batteries is observed for various states of charge at cryogenic temperatures. The EPR-detected state of charge (ESOC), as inferred from the number of paramagnetic centers in the film, is compared to the results of Coulomb counting based on galvanostatic charging. Spin concentration, longitudinal relaxation times T(1 )and phase memory times T-m strongly correlate with the ESOC. In the discharged film, the spin concentration reaches 5 +/- 3x10(20) cm(-3), causing a phase memory time T-m << 100 ns (shorter than the resonator ring-down time) that hinders the detection of the spin echo. In the charged film, the decreased spin concentration results in a longer T-m between 100 ns and 300 ns that enables spin-echo detection, yet limits the length of the microwave pulse sequence. The short, broad-band pulses cause instantaneous diffusion in the unoxidized domains across the oxidized film, affecting the relative peak intensities in the pulsed EPR spectrum. By simulating the spectral distortion caused by instantaneous diffusion, we obtain information on the local spin concentration, which complements the information on the 'bulk' spin concentration determined by electrochemistry and continuous-wave EPR spectroscopy

a [Ni(Salen)]‐TEMPO redox‐conducting polymer for organic batteries

Redox-active nitroxyl-containing polymers are promising candidates as possible replacements for inorganic based energy-storage materials, due to their high energy density and fast redox kinetics. One challenge towards the implementation of such a system is the insufficient electrical conductivity, impeding the charge collection even with highly conductive additives. Herein, the first implementation of a polymeric bis(salicylideniminato) nickel (NiSalen) conductive backbone as an active charge-collecting wire is reported. NiSalen simultaneously serves as a charge collector for nitroxyl pendants and supports the redox capacity of the material. This novel polymer exhibits a specific capacity of up to 91.5 mAh g−1, retaining 87 % of its theoretical capacity at 800 C and more than 30 % at as high as 3000 C (66 % capacity retention after 2000 cycles). The properties of the new material upon operation was studied by means of operando electrochemical methods, UV-Vis, and electron paramagnetic resonance spectroscopy

Efficacy of liposomal dosage forms and hyperosmolar salines in experimental pharmacotherapy of acute lung injury

Hypertonic sodium chloride solutions and liposomal drugs with pulmotropic effect are of great interest for the treatment of acute lung injury (ALI). For the experiment, liposomes with dexamethasone, N-acetylcysteine (NAC), aprotinin and dye Cyanine-7 (Cy-7) were obtained. A liposome analysis was performed by means of spectrophotometry. ALI was modeled in rats by the administration of the damaging agents into the trachea. All the studied therapeutic agents increased the survival rate of the laboratory animals with ALI. The most effective experimental agent was liposomal dexamethason

Spins at work: probing charging and discharging of organic radical batteries by electron paramagnetic resonance spectroscopy

Organic radical batteries (ORBs) are a promising class of electrochemical power sources employing organic radicals as redox-active groups. This article reports on the development of a versatile on-substrate electrode setup for spectroelectrochemical Electron Paramagnetic Resonance (EPR) measurements on redox conductive polymers for ORBs. Quantitative in operando EPR experiments performed on electrochemical cells with a di-TEMPO Ni-Salen polymer as active electrode material demonstrate a strong decrease in the number of paramagnetic centers upon oxidizing the film. The distinct EPR signatures of the TEMPO-containing polymer and its fragments in different molecular environments are used to study its degradation upon repeated cycling. A comparison between the number of EPR-active sites and the number of electrochemically active charges, as measured by cyclic voltammetry, provides information on the nature of the degradation process. Low-temperature ex situ pulse EPR measurements on the oxidized polymer film reveal the spectrum of dilute nitroxide species, which may be associated with electrochemically inactive islands. These experiments pave the way for advanced EPR techniques for accurately determining distances between adjacent paramagnetic centers and thus for identifying performance-limiting loss mechanisms, which can eventually help develop strategies for making ORBs powerful contenders on the path towards sustainable electrochemical power sources

Optical coherence microangiography of the mouse kidney for diagnosis of circulatory disorders

Optical coherence tomography (OCT) has become widespread in clinical applications in which precise three-dimensional functional imaging of living organs is required. Nevertheless, the kidney is inaccessible for the high resolution OCT imaging due to a high light attenuation coefficient of skin and soft tissues that significantly limits the penetration depth of the probing laser beam. Here, we introduce a surgical protocol and fixation scheme that enables functional visualization of kidney’s peritubular capillaries via OCT microangiography. The model of reversible/irreversible glomerulus embolization using drug microcarriers confirms the ability of OCT to detect circulatory disorders. This approach can be used for choosing optimal carriers, their dosages and diagnosis of other blood flow pathologies

Ocean-bottom seismographs based on broadband MET sensors: architecture and deployment case study in the Arctic

The Arctic seas are now of particular interest due to their prospects in terms of hydrocarbon extraction, development of marine transport routes, etc. Thus, various geohazards, including those related to seismicity, require detailed studies, especially by instrumental methods. This paper is devoted to the ocean-bottom seismographs (OBS) based on broadband molecular–electronic transfer (MET) sensors and a deployment case study in the Laptev Sea. The purpose of the study is to introduce the architecture of several modifications of OBS and to demonstrate their applicability in solving different tasks in the framework of seismic hazard assessment for the Arctic seas. To do this, we used the first results of several pilot deployments of the OBS developed by Shirshov Institute of Oceanology of the Russian Academy of Sciences (IO RAS) and IP Ilyinskiy A.D. in the Laptev Sea that took place in 2018–2020. We highlighted various seismological applications of OBS based on broadband MET sensors CME-4311 (60 s) and CME-4111 (120 s), including the analysis of ambient seismic noise, registering the signals of large remote earthquakes and weak local microearthquakes, and the instrumental approach of the site response assessment. The main characteristics of the broadband MET sensors and OBS architectures turned out to be suitable for obtaining high-quality OBS records under the Arctic conditions to solve seismological problems. In addition, the obtained case study results showed the prospects in a broader context, such as the possible influence of the seismotectonic factor on the bottom-up thawing of subsea permafrost and massive methane release, probably from decaying hydrates and deep geological sources. The described OBS will be actively used in further Arctic expeditions

Demonstration of the temporal matter-wave Talbot effect for trapped matter waves

We demonstrate the temporal Talbot effect for trapped matter waves using ultracold atoms in an optical lattice. We investigate the phase evolution of an array of essentially non-interacting matter waves and observe matter-wave collapse and revival in the form of a Talbot interference pattern. By using long expansion times, we image momentum space with sub-recoil resolution, allowing us to observe fractional Talbot fringes up to 10th order.Comment: 17 pages, 7 figure

Pion, kaon, proton and anti-proton transverse momentum distributions from p+p and d+Au collisions at sNN=200\sqrt{s_{NN}} = 200 GeV

Identified mid-rapidity particle spectra of $\pi^{\pm}$, $K^{\pm}$, and $p(\bar{p})$ from 200 GeV p+p and d+Au collisions are reported. A time-of-flight detector based on multi-gap resistive plate chamber technology is used for particle identification. The particle-species dependence of the Cronin effect is observed to be significantly smaller than that at lower energies. The ratio of the nuclear modification factor ($R_{dAu}$) between protons $(p+\bar{p})$ and charged hadrons ($h$) in the transverse momentum range $1.2<{p_{T}}<3.0$ GeV/c is measured to be $1.19\pm0.05$(stat)$\pm0.03$(syst) in minimum-bias collisions and shows little centrality dependence. The yield ratio of $(p+\bar{p})/h$ in minimum-bias d+Au collisions is found to be a factor of 2 lower than that in Au+Au collisions, indicating that the Cronin effect alone is not enough to account for the relative baryon enhancement observed in heavy ion collisions at RHIC.Comment: 6 pages, 4 figures, 1 table. We extended the pion spectra from transverse momentum 1.8 GeV/c to 3. GeV/

Azimuthal anisotropy at RHIC: the first and fourth harmonics

We report the first observations of the first harmonic (directed flow, v_1), and the fourth harmonic (v_4), in the azimuthal distribution of particles with respect to the reaction plane in Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC). Both measurements were done taking advantage of the large elliptic flow (v_2) generated at RHIC. From the correlation of v_2 with v_1 it is determined that v_2 is positive, or {\it in-plane}. The integrated v_4 is about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8) harmonics upper limits on the magnitudes are reported.Comment: 6 pages with 3 figures, as accepted for Phys. Rev. Letters The data tables are at http://www.star.bnl.gov/central/publications/pubDetail.php?id=3