In this study, we demonstrated the unique capability of carbon-based ion-selective electrode (ISE) to perform highly sensitive square wave anodic stripping voltammetry, while maintaining all the ...properties of an ISE, in terms of sensitivity, detection limit, response time and selectivity. Square wave anodic stripping voltammetry involves deposition and dissolution steps of metal ions, which means adsorption and desorption of metal ions on the conductive ion-selective membrane without losing its ion-sensing property. To demonstrate this capability, we chose a Ca2+ ion-selective microelectrode (µISE) as a potentiometric method and Cu2+-stripping voltammetry as an amperometric method. The carbon-based ISE surface is capable of quantifying nanomolar to micromolar Cu2+ in both a standard acetate buffer and a complex water sample. The Ca2+-µISE also showed a Nernstian slope of 29 mV/log Ca2+ and a detection limit of 1 µM within the linear range of 1 µM to 10 mM. It thus opens an opportunity to use the low detection limit of anodic stripping voltammetry and the high selectivity of ISE-based potentiometry.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Department of Pharmacology, University of Iowa, Iowa City, Iowa
This review addresses the localized regulation of voltage-gated ion channels by phosphorylation. Comprehensive data on channel ...regulation by associated protein kinases, phosphatases, and related regulatory proteins are mainly available for voltage-gated Ca 2+ channels, which form the main focus of this review. Other voltage-gated ion channels and especially K v 7.1-3 (KCNQ1-3), the large- and small-conductance Ca 2+ -activated K + channels BK and SK2, and the inward-rectifying K + channels K ir 3 have also been studied to quite some extent and will be included. Regulation of the L-type Ca 2+ channel Ca v 1.2 by PKA has been studied most thoroughly as it underlies the cardiac fight-or-flight response. A prototypical Ca v 1.2 signaling complex containing the β 2 adrenergic receptor, the heterotrimeric G protein G s , adenylyl cyclase, and PKA has been identified that supports highly localized via cAMP. The type 2 ryanodine receptor as well as AMPA- and NMDA-type glutamate receptors are in close proximity to Ca v 1.2 in cardiomyocytes and neurons, respectively, yet independently anchor PKA, CaMKII, and the serine/threonine phosphatases PP1, PP2A, and PP2B, as is discussed in detail. Descriptions of the structural and functional aspects of the interactions of PKA, PKC, CaMKII, Src, and various phosphatases with Ca v 1.2 will include comparisons with analogous interactions with other channels such as the ryanodine receptor or ionotropic glutamate receptors. Regulation of Na + and K + channel phosphorylation complexes will be discussed in separate papers. This review is thus intended for readers interested in ion channel regulation or in localization of kinases, phosphatases, and their upstream regulators.
Nickel–iron catalysts represent an appealing platform for electrocatalytic oxygen evolution reaction (OER) in alkaline media because of their high adjustability in components and activity. However, ...their long‐term stabilities under high current density still remain unsatisfactory due to undesirable Fe segregation. Herein, a nitrate ion (NO3−) tailored strategy is developed to mitigate Fe segregation, and thereby improve the OER stability of nickel–iron catalyst. X‐ray absorption spectroscopy combined with theoretical calculations indicate that introducing Ni3(NO3)2(OH)4 with stable NO3− in the lattice is conducive to constructing the stable interface of FeOOH/Ni3(NO3)2(OH)4 via the strong interaction between Fe and incorporated NO3−. Time of flight secondary ion mass spectrometry and wavelet transformation analysis demonstrate that the NO3− tailored nickel–iron catalyst greatly alleviates Fe segregation, exhibiting a considerably enhanced long‐term stability with a six‐fold improvement over FeOOH/Ni(OH)2 without NO3− modification. This work represents a momentous step toward regulating Fe segregation for stabilizing the catalytic performances of nickel–iron catalysts.
The NO3− tailored FeOOH/Ni3(NO3)2(OH)4 catalyst greatly alleviates Fe segregation via the chemical interaction of Fe and NO3−, exhibiting a considerably enhanced long‐term stability with a six‐fold improvement over FeOOH/Ni(OH)2 without NO3− modification.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Adsorption techniques are widely used to remove pollutants from wastewater; however, composites are gaining more importance due to their excellent adsorption properties. Bentonite composite with ...Eriobotrya japonica seed was prepared and used for the adsorption of copper (Cu) metal from aqueous media. The process variables such as pH, Cu(II) ions initial concentration, adsorbent dose, contact time and temperature were optimized for maximum Cu(II) adsorption. At pH 5, adsorbent dose 0.1 g, contact time 45 min, Cu(II) ions initial concentration 75 mg/L and temperature 45 °C, maximum Cu(II) adsorption was achieved. Desorption studies revealed that biocomposite is recyclable. Langmuir, Freundlich and Harkins-Jura isotherms as well as pseudo-first and pseudo-second–order kinetics models were applied to understand the adsorption mechanism. Thermodynamic parameters (ΔG0, ΔH0 and ΔS0) suggest that the adsorption process was spontaneous and endothermic in nature. The pseudo-second-order kinetic model and Langmuir isotherm fitted well to the adsorption data. Results showed that biocomposite was more efficient for Cu(II) adsorption in comparison to individuals native Eriobotrya japonica seed biomass and Na-bentonite.
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•Biocomposite was prepared from bentonite and E. japonica seed powder.•Biocomposite was used for copper adsorption and process variables were optimized.•Isotherms, kinetics, thermodynamics and desorption studies were performed.•Biocomposite affinity for copper was excellent versus native biomass and bentonite.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Growth of NdCl⋅36H2O single crystal using a non-linear cooling protocol.•Spectral characteristics of Nd3+ ions in NdCl⋅36H2O crystal.•Analysis of non-radiative transition caused by multi-phonon ...relaxation.•Proposed applications in strain sensing using its special characteristics of 4f electron.
Rare-earth-ion-doped crystals have been a promising candidate material for optical quantum memory, which is the fundamental building block for quantum networks. The unwanted broadening caused by rare-earth dopants can impose limits to the available absorption in the doped crystals. To solve this problem, stoichiometric rare-earth crystals have been considered, such as EuCl⋅36H2O crystal, whose inhomogeneous broadening is measured to be 25 MHz with an extremely strong absorption. Stoichiometric rare-earth crystals that contain Kramers ions could further fulfill the requirements for broadband quantum storage and interfacing with microwave photons. Here we grow NdCl⋅36H2O single crystals and perform optical absorption and emission spectroscopy of this material.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Here, we report the first direct thermal conductivity measurement results for Al–UMo interaction layer (IL), which is typically observed in UMo/Al dispersion fuel plates under irradiation. The ...investigated IL was formed by irradiating Al coated UMo substrate using 80 MeV iodine ions at 180∘C up to 3.03×1017 ions/cm2 fluence. Microstructural characterization indicated that the induced IL is amorphous with an approximately (U0.8,Mo0.2)Al5.3 stoichiometry, which is similar to that formed under in-pile irradiation. Focused ion beam (FIB) was used to prepare nine specimens of various lengths from the IL that could be suspended across a microfabricated device for thermal conductivity measurement. The measured thermal conductivity values of the IL were significantly lower than the values for both the original UMo fuel and the Al. The successful measurement of the Al–UMo IL provides valuable information for the development and qualification of UMo/Al dispersion fuels for research and test reactor conversion applications, and further demonstrates the promising capabilities of utilizing the suspended bridge method in nuclear fuel research.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Al3+ ions significantly promoted the depression of talc by CMC.•Al3+ ions adsorbed onto the talc surface in the form of AlOH species.•CMC can be effectively adsorbed onto the talc surface with AlOH ...species.•The morphology of CMC on talc surface changed obviously by Al3+ ions.
Talc is a gangue mineral of many sulfide minerals, which is naturally hydrophobic. The depression of talc is very important and challenging in sulfide ore flotation. This research introduced aluminum ions into the process of using carboxymethyl cellulose (CMC) to depress talc. Flotation experiment results showed that aluminum ions used alone exerted a weak depression effect on talc, and that aluminum ions used in conjunction with CMC effectively depressed the flotation of talc at pH 8.5. Results of X-ray photoelectron spectroscopy and adsorption tests showed that the interaction of aluminum ions with talc changed the surface of talc, and Al(OH)3 formed on the talc surfaces, thereby promoting the adsorption of CMC onto talc and depressing the flotation of talc. On this basis, the morphology of CMC on the talc surface was observed by atomic force microscopy imaging. With the addition of aluminum ions, CMC aggregated to a greater extent, multiple layers adsorbed onto the surface of talc, and the coverage of CMC substantially increased. Based on all tests and analysis, the mechanism of the synergistic effect of CMC and aluminum ions on talc flotation was also proposed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Modifications and resulting changes in various properties of nanocrystalline HfO2 high-k dielectric thin films with nominal thickness of 20 nm grown by atomic layer deposition technique on silicon ...and glass substrates were investigated as a function of swift heavy ions (SHI) irradiation. In the present work, our attention is to study the electronic excitation induced modifications in HfO2 thin films cause of formation of defects by 120 MeV Au9+(SHI) irradiation. For the same purpose, the annealed (500 °C) HfO2 thin films were irradiated with the varying fluence in the range of 1E11 to 1E13 ions/cm2. The virgin and irradiated representative HfO2 thin films were investigated by various techniques. The substantial root mean square (RMS) surface roughness (0.5–1 nm) and variation in grain size (40–52 nm) as a function of Au9+ ions irradiation were determined using atomic force microscope (AFM). The optical properties of HfO2 thin films were analyzed by measuring absorbance and transmission (54–62%) spectra in 200–700 nm wavelength range followed by calculation of optical band gap (Eg). The photoluminescence (PL) spectra obtained at excitation wavelength 220 nm indicate the formation of defects due to SHI irradiation. A change in excitation wavelength (220–260 nm) causes the shift in emission peaks towards higher wavelength. Structural investigations have been carried by Grazing Incidence X-ray Diffraction (GIXRD) techniques which reveal the variation in crystallite size as a function of different fluence. The results of a systematic XPS study of virgin and SHI irradiated samples shows the shifting of Hf 4f and O 1s peaks towards lower binding energy as compared to virgin sample. O K-edge XANES were performed to understand the ion-beam irradiation induced defect formation and their consequences on the electronic structure of HfO2 thin films. The obtained peaks in Rutherford backscattering spectrometry (RBS) affirm the existence of Hf and O elements and width of the peaks determine the sample thickness (20 nm).
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•HfO2 thin films were grown by Thermal-atomic layer deposition.•SHI irradiation performed on grown films using 120 MeV Au9+ ions.•Statistical information of roughness of films determined using PSD.•Binding energy of Hf 4f and O 1s determined using XPS.•XANES used for investigation of electronic structure of HfO2thin films.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Native mass spectrometry and collision-induced unfolding (CIU) workflows continue to grow in utilization due to their ability to rapidly characterize protein conformation and stability. To perform ...these experiments, the instrument must be capable of collisionally activating ions prior to ion mobility spectrometry (IMS) analyses. Trapped ion mobility spectrometry (TIMS) is an ion mobility implementation that has been increasingly adopted due to its inherently high resolution and reduced instrumental footprint. In currently deployed commercial instruments, however, typical modes of collisional activation do not precede IMS analysis, and thus, the instruments are incapable of performing CIU. In this work, we expand on a recently developed method of activating protein ions within the TIMS device and explore its analytical utility toward the unfolding of native-like protein ions. We demonstrate the unfolding of native-like ions of ubiquitin, cytochrome C, β-lactoglobulin, and carbonic anhydrase. These ions undergo extensive unfolding upon collisional activation. Additionally, the improved resolution provided by the TIMS separation uncovers previously obscured unfolding complexity.
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