Rotating frame zeugmatography

The proton sensitivity obtainable at 5 MHz from a baby is sufficiently large to suggest the possibility of obtaining images with millimetre solution in seconds. Such goals present difficulties; for example, the high quality factor of the receiving coil necessary for good sensitivity limits the receiver bandwidth and leads to long pulse recovery times, and large, rapidly switched field gradients require power engineering. Solutions to these problems are being pursued at the National Institutes of Health (N.I.H.), where a high speed imaging system is under construction. For example, bandwidth and recovery time problems may be resolved with the aid of a low noise preamplifier with imaginary gain and Miller feedback, large gradients may be generated with a magnet comprising two rotatable hemispherical windings and switching of gradients may be eliminated by performing zeugmatography in the rotating frame. It is upon this latter aspect of the design that the present article concentrates.     

Anode break excitation in Chara membrane

The anode break excitation in Chara membrane was analyzed witha model consisting of an electromotive force (emf) in serieswith a resistance r ( = l/g). The emf was found to shift towarddepolarization during supply of an inward current. Wheneverthe shift of the emf went beyond a threshold depolarization,an action potential was brought about after the end of or evenduring the inward current supply. (Received September 24, 1974; )     

Inward Rotating Spiral Waves in Glycolysis

We report on the first observation of inward rotating spiral waves (antispirals) in a biochemical reaction-diffusion system. Experiments are performed with extracts from yeast cells in an open spatial reactor. By increasing the protein concentration of the extract we observe a transition from outward to inward propagating waves of glycolytic activity. Numerical simulations with an allosteric model for the phosphofructokinase can reproduce these inward propagating waves over a wide range of parameters if the octameric structure of yeast phosphofructokinase is taken into account.     

Steel Anti-Corrosion Strategy Enables Long-Cycle Zn Anode

The progress of aqueous zinc batteries (AZBs) is limited by the poor cycling life due to Zn anode instability, including dendrite growth, surface corrosion, and passivation. Inspired by the anti-corrosion strategy of steel industry, a compounding corrosion inhibitor (CCI) is employed as the electrolyte additive for Zn metal anode protection. It is shown that CCI can spontaneously generate a uniform and ≈30 nm thick solid-electrolyte interphase (SEI) layer on Zn anode with a strong adhesion via Zn O bonding. This SEI layer efficiently prohibits water corrosion and guides homogeneous Zn deposition without obvious dendrite formation. This enables reversible Zn deposition and dissolution for over 1100 h under the condition of 1 mA cm⁻² and 1 mAh cm⁻² in symmetric cells. The Zn-MnO₂ full cells with CCI-modified electrolyte deliver an ultralow capacity decay rate (0.013% per cycle) at 0.5 A g⁻¹ over 1000 cycles. Such an innovative strategy paves a low-cost way to achieve AZBs with long lifespan.     

Adiabatic Heteronuclear Decoupling in Rotating Solids

In magic angle spinning solid state NMR experiments the potential of heteronuclear (1)H decoupling employing a continuous train of adiabatic inversion pulses has been assessed via numerical simulations and experimental measurements. It is shown that, with a (1)H RF field strength of approximately 100 kHz that is typically available in MAS NMR probes, it is possible to achieve efficient adiabatic (1)H decoupling at low magic angle spinning frequencies. It is pointed out that in the presence of H (1) inhomogeneities it will be advantageous to employ adiabatic decoupling in MAS solid state NMR experiments.     

Anode Break Excitation in Space-Clamped Squid Axons

Strength-duration curves for space-clamped squid axons, using square wave anode breaks as stimuli, established the existence of four distinct regions. For the average experimental axon the intersection of the first two regions, τ₁, occurs at about 7 msec. This agrees with computations based on the Hodgkin-Huxley (HH) equations and corresponds to the accommodation time constant found previously for a linearly rising ramp, as given by the HH equations and as found experimentally. The second break in the curve, τ₂, at about 200 msec, and the third break, τ₃, at 1 sec, are far beyond the range of the HH equations and may be the counterpart in the excitability of the long time constants, which have been apparent from a number of other types of experiments. The regions of the curve before 1 msec and beyond 2 or 3 sec are quite variable and may represent breakdown. Rheobase increases in both experimental and computed axons when temperature is raised. In both experimental and computed axons τ₁ descreases slightly when the temperature is raised from 10 to 15°C. At 20 and 25°C, τ₁ of the experimental axon increases markedly.     

Work Function Evolution in Li Anode Processing

Toward improved understanding and control of the interactions of Li metal anodes with their processing environments, a combined X‐ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and density functional theory (DFT) characterization of the effects that O₂, CO₂, and N₂, the main gases in dry‐atmosphere battery production lines, induced on a reproducibly clean Li surface at room temperature is presented here. XPS measurements demonstrate that O₂ is ten times more effective than CO₂ at oxidizing metal Li. Notably, pure N₂ is shown to not dissociate on clean metal Li. UPS results indicate that decomposition of O₂ (CO₂) reduces the work function of the Li surface by almost 1 eV, therefore increasing the reduction energy drive for the treated substrate by comparison to bare metallic Li. DFT simulations semiquantitatively account for these results on the basis of the effects of dissociative gas adsorption on the surface dipole density of the Li surface.     

Alloy Anode Materials for Rechargeable Mg Ion Batteries

Rechargeable magnesium ion batteries are interesting as one of the alternative metal ion battery systems to lithium ion batteries due to the wide availability and accessibility of magnesium in the earth's crust. On the one hand, electrolyte solutions in which Mg metal anodes are fully reversible are not suitable for the use of high voltage/high capacity transition metal oxide cathodes due to complex surface phenomena. On the other hand, Mg metal anodes cannot work reversibly in conventional electrolyte solutions in which high voltage/high capacity Mg insertion cathodes can work because of passivation phenomena that fully block them. Replacing Mg metal with alternative anodes that can work reversibly in conventional electrolyte solutions could provide a promising route to elaborate high voltage and high capacity rechargeable Mg battery systems. Herein, the recent progress in alloy anodes based on group IIIA, IVA, VA elements is summarized. The theoretical evaluations, achievable capacities, synthetic strategies, battery test configurations, electrochemical properties, and underlying reaction mechanisms are systematically summarized and discussed. The key issues and challenges impeding their current use are identified and some valuable suggestions for their future development as practical reversible anodes for Mg batteries are provided.     

Capillary Tube Catalase Test

A capillary tube procedure for detection of catalase activities of isolated colonies of pure and mixed cultures on nutrient and blood agar plates is proposed.     

Capillary Tube Catalase Test

A capillary tube procedure for detection of catalase activities of isolated colonies of pure and mixed cultures on nutrient and blood agar plates is proposed.