首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Printed batteries are an emerging solution for integrated energy storage using low‐cost, high accuracy fabrication techniques. While several printed batteries have been previously shown, few have designed a battery that can be incorporated into an integrated device. Specifically, a fully printed battery with a small active electrode area (<1 cm2) achieving high areal capacities (>10 mAh cm?2) at high current densities (1–10 mA cm?2) has not been demonstrated, which represents the minimum form‐factor and performance requirements for many low‐power device applications. This work addresses these challenges by investigating the scaling limits of a fully printed Zn–Ag2O battery and determining the electrochemical limitations for a mm2‐scale battery. Processed entirely in air, Zn–Ag2O batteries are well suited for integration in typical semiconductor packaging flows compared to lithium‐based chemistries. Printed cells with electrodes as small as 1 mm2 maintain steady operating voltages above (>1.4 V) at high current densities (1–12 mA cm?2) and achieve the highest reported areal capacity for a fully printed battery at 11 mAh cm?2. The findings represent the first demonstration of a small, packaged, fully printed Zn–Ag2O battery with high areal capacities at high current densities, a crucial step toward realizing chip‐scale energy storage for integrated electronic systems.  相似文献   

2.
Photoelectrochemical (PEC) systems have been researched for decades due to their great promise to convert sunlight to fuels. The majority of the research on PEC has been using light to split water to hydrogen and oxygen, and its performance is limited by the need of additional bias. Another research direction on PEC using light, is to decompose organic materials while producing electricity. In this work, the authors report a new type of unassisted PEC system that uses light, water and oxygen to simultaneously produce electricity and hydrogen peroxide (H2O2) on both the photoanode and cathode, which is essentially a light‐driven fuel cell with H2O2 as the main product at the two electrodes, meanwhile achieving a maximum power density of 0.194 mW cm‐2, an open circuit voltage of 0.61 V, and a short circuit current density of 1.09 mA cm‐2. The electricity output can be further used as a sign for cell function when accompanied by a detector such as a light‐emitting diode (LED) light or a multimeter. This is the first work that shows H2O2 two‐side generation with a strict key factors study of the system, with a clear demonstration of electricity output ability using low‐cost earth abundant materials on both sides, which represents an exciting new direction for PEC systems.  相似文献   

3.
Fourier transform infrared transmission spectra have been obtained of the enzyme ribonuclease in both H2O and 2H2O. The resolution of the spectra have been enhanced by Fourier self-deconvolution procedures. The infrared spectrum of ribonuclease changes during exchange of the enzyme's amide hydrogens for deuterium and the exchange has been followed in the amide I and amide II spectral regions. The amide I band shifts towards lower wavenumbers during both the fast and slow phases of hydrogen exchange and the interpretation of these shifts has aided the band assignments. In particular these studies have allowed an assignment to be made for the high frequency component of the β-strand absorption that differs from that proposed previously. This paper represents the first example of the use of deconvoluted Fourier transform infrared spectra in conjunction with hydrogen-deuterium exchange in order to aid in the assignment of a proteins's infrared bands.  相似文献   

4.
Sulfur dioxide (SO2) in the atmosphere has been demonstrated to have many adverse impacts on the environment and human health. In this study, deposition of SO2 ranging from 9.0 to 127.8 mg kg?1 with an average of 35.7 mg S kg?1 was found to substantially stimulate NO and N2O emissions from soils in the humid subtropical areas of Hainan, Fujian, Jiangxi, and Yunnan provinces of China under field conditions. Laboratory tests indicated that the stimulations were mediated biologically as the effects were not observed in sterilized soils. Acidification of soil resulting from SO2 deposition was not responsible for the stimulated NO and N2O emissions alone as the stimulation did not occur by acidifying soil with HNO3 treatment. By using the 15N tracing method, we found that the N2O emissions stimulated by SO2 deposition were from either denitrification, heterotrophic nitrification or both, but not from autotrophic nitrification. Therefore, atmospheric SO2 deposition would most likely stimulate NO and N2O emissions in acidic soils in which heterotrophic nitrification dominates NO and N2O production and waterlogged soils in which denitrification dominates NO and N2O production.  相似文献   

5.
The effect of hydrogen peroxide (H2O2) on cytosolic free calcium concentration ([Ca2+]c) as well as its effect on glutamate secretion in rat hippocampal astrocytes have been the aim of the present research. Our results show that 100 μM H2O2 induces an increase in [Ca2+]c, that remains at an elevated level while the oxidant is present in the perfusion medium, due to its release from intracellular stores as it was observed in the absence of extracellular Ca2+, followed by a significant increase in glutamate secretion. Ca2+-mobilization in response to the oxidant could only be reduced by thapsigargin plus FCCP, indicating that the Ca2+-mobilizable pool by H2O2 includes both endoplasmic reticulum and mitochondria. We conclude that ROS in hippocampal astrocytes might contribute to an elevation of resting [Ca2+]c which, in turn, could lead to a maintained secretion of the excitatory neurotransmitter glutamate, which has been considered a situation potentially leading to neurotoxicity in the hippocampus.  相似文献   

6.
Thermoluminescence (TL) measurements were carried out on europium (Eu) doped magnesium pyrophosphate (Mg2P2O7) nanopowders using gamma irradiation in the dose range of 0.1 to 3 kGy. The powder samples were successfully synthesized by chemical co‐precipitation synthesis route. The formation and crystallinity of the compound was confirmed by powder X‐ray diffraction (PXRD) pattern. The estimated particle size was found to be in nanometer scale by using Debye Scherer's formula. A scanning electron microscopy (SEM) study was carried out for the morphological characteristics of as synthesized Mg2P2O7:Eu phosphor. Photoluminescence (PL) study was carried out to confirm the presence of the rare‐earth ion and its valence state. The TL analysis of synthesized samples were performed after the irradiation of Mg2P2O7:Eu with cobalt‐60 (60Co) gamma rays. The high and low intensity peaks of TL glow curve appeared at around 400 K, 450 K, 500 K and 596 K respectively. The appreciable shift in peak positions has been observed for different concentrations of Eu ion. The trapping parameters, namely activation energy (E), order of kinetics (b) and frequency factor (s) have been determined using thermal cleaning process, peak shape (Chen's) method and glow curve deconvolution (GCD) functions.  相似文献   

7.
Low-energy visible light (LEVL) has previously been found to modulate various processes in different biological systems. One explanation for the stimulatory effect of LEVL is light-induced reactive oxygen species formation. In the present study, both sperm and skin cells were illuminated with LEVL and were found to generate singlet oxygen (1O2). The detection of 1O2 was performed using a trapping probe, 2,2,6,6-tetramethyl-4-piperidone, coupled with electron paramagnetic resonance spectroscopy. In addition, we have shown that, together with 1O2 generation, LEVL illumination increases the reductive capacity of the cells, which explains the difficulties encountered in 1O2 detection. The potential of visible light to change the cellular redox state may explain the recently observed biostimulative effects exerted by LEVL.  相似文献   

8.
Four series of borosilicate glasses modified by alkali oxides and doped with Tb3+ and Sm3+ ions were prepared using the conventional melt quenching technique, with the chemical composition 74.5B2O3 + 10SiO2 + 5MgO + R + 0.5(Tb2O3/Sm2O3) [where R = 10(Li2O /Na2O/K2O) for series A and C, and R = 5(Li2O + Na2O/Li2O + K2O/K2O + Na2O) for series B and D]. The X‐ray diffraction (XRD) patterns of all the prepared glasses indicate their amorphous nature. The spectroscopic properties of the prepared glasses were studied by optical absorption analysis, photoluminescence excitation (PLE) and photoluminescence (PL) analysis. A green emission corresponding to the 5D47F5 (543 nm) transition of the Tb3+ ions was registered under excitation at 379 nm for series A and B glasses. The emission spectra of the Sm3+ ions with the series C and D glasses showed strong reddish‐orange emission at 600 nm (4G5/26H7/2) with an excitation wavelength λexci = 404 nm (6H5/24F7/2). Furthermore, the change in the luminescence intensity with the addition of an alkali oxide and combinations of these alkali oxides to borosilicate glasses doped with Tb3+ and Sm3+ ions was studied to optimize the potential alkali‐oxide‐modified borosilicate glass.  相似文献   

9.
Penicillium citrinum cultures have been germinated on an H2O-based medium, resuspended on a D2O-based medium and treated with [l,2-13C2] acetate. The resulting citrinin (1) has been analysed by2H and13C nuclear magnetic resonance spectroscopy and information about the metabolism of hydrogen in citrinin biosynthesis has been deduced.  相似文献   

10.
This article reports on the luminescence properties of rare earth (Dy3+ and Tm3+)ions doped SrGa2Si2O8 phosphor were studied. SrGa2Si2O8phosphors weresynthesizedby employing solid state reaction method.From the measured X‐ray diffraction (XRD) pattern of the samplemonoclinic phase structure has been observed. Thermoluminescenceand Mechanoluminescence properties of the γ‐ray irradiated samples have been studied. Photoluminescence spectra of Dy3+ activated SrGa2Si2O8phosphor has been measured with an excitation wavelength at 348 nm,and it shows two emission bands at 483 and 574 nm due to 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions respectively. Whereas the photoluminescence spectra of Tm3+ activated SrGa2Si2O8 phosphor has been measured with an excitation wavelength at 359 nm and it exhibits two emission bands at 454 and 472 nm due to 1D2 → 3F4 and1G4 → 3H6 transitions respectively. In thermoluminescence study, γ‐irradiatedthermoluminescence glow curve of SrGa2Si2O8:Dy3+ phosphor shows two well defined peaks at 293 °C (peak1)and 170 °C (peak2) whereas thermoluminescence glow curve of SrGa2Si2O8:Tm3+ phosphor shows peaks at 292 °C (peak1) and 184 °C (peak2) indicating that two sets of traps are being activated within the particular temperature range and the trapping parameters associated with the prominent glow peaks of SrGa2Si2O8:Dy3+ and SrGa2Si2O8:Tm3+ are calculated using Chen's peak shape and initial rise method.From the Mechanoluminescence study, only one glow peak has been observed. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

11.
The uptake of ammonia and O2 by washed cells of Nitrosomonas has been followed simultaneously and continuously using electrode techniques. The stoichiometry of NH 4 + oxidation, O2 uptake and NO 2 - production was 1 : 1.5 : 1.0 and for NH2OH oxidation a ratio of 1 for O2 : NO 2 - . A variety of inhibitors of electron transport and metals as well as uncouplers restricted ammonia uptake more markedly than O2 utilization. There is good evidence for the involvement of copper in the NH 4 + uptake process.A quinacrine fluorescence technique has been used to study the proton extrusion by washed cells on adding NH4Cl and NH2OH respectively as substrates. The uptake of NH 4 + was followed by the extrusion of H+ and this process was depressed by those inhibitors which were also effective in the electrode experiments. A requirement for copper is also established for the translocation of protons into the medium, resulting from the uptake of NH 4 + by cells.Abbreviations mCCCP carbonyl cyanide m-chlorophenylhydrazone - DBP 2,4 dibromophenol - DCCD N-N-dicyclohexylcarbodimide - DIECA Sodium diethyldithiocarbamate - DNP 2,4 dinitrophenol - HOQNO 2-heptyl-4-hydroxyquinoline-N-oxide - NBD chloride 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole - N-serve 2-chloro-6-trichloromethyl-pyridine - PCP pentachlorophenol - 2-TMP 2-trichloromethyl-pyridine - TPB tetraphenylboron - TTFA 1-[thenoyl-(2)]-3,3,3-trifluoracetone - KSCN Potassium thiocyanate  相似文献   

12.
Hydrofluoroethers are being considered as potential candidates for third generation refrigerants. The present investigation involves the ab initio quantum mechanical study of the decomposition mechanism of CF3OCH2O radical formed from a hydrofluoroether, CF3OCH3 (HFE-143a) in the atmosphere. The geometries of the reactant, products and transition states involved in the decomposition pathways are optimized and characterized at the DFT (B3LYP) level of theory using 6-311G(d,p) basis set. Energy calculations have been performed at the G2(MP2) and G2M(CC,MP2) level of theory. Two prominent decomposition channels, C-O bond scission and reaction with atmospheric O2 have been considered for detailed investigation. Studies performed at the G2(MP2) level reveals that the decomposition channel involving C-O bond scission occurs with a barrier height of 23.8 kcal mol−1 whereas the oxidative pathway occurring with O2 proceeds with an energy barrier of 7.2 kcal mol−1. On the other hand the corresponding values at G2M(CC,MP2) are 24.5 and 5.9 kcal mol−1 respectively. Using canonical transition state theory (CTST) rate constants for the two pathways considered are calculated at 298 K and 1 atm pressure and found to be 5.9 × 10−6 s−1 and 2.3 × 10−5 s−1 respectively. The present study concludes that reaction with O2 is the dominant path for the consumption of CF3OCH2O in the atmosphere. Transition states are searched and characterized on the potential energy surfaces involved in both of the reaction channels. The existence of transition state on the corresponding potential energy surface is ascertained by performing intrinsic reaction coordinate (IRC) calculation.  相似文献   

13.
In this work, we report the preparation, characterization, comparison and luminescence mechanisms of Eu2+‐doped and Eu2+,Dy3+‐co‐doped Ba2MgSi2O7 (BMSO) phosphors. Prepared phosphors were synthesized via a high temperature solid‐state reaction method. All prepared phosphors appeared white. The phase structure, particle size, and elemental analysis were analyzed using X‐ray diffraction (XRD), transmission electron microscopy (TEM) and energy‐dispersive X‐ray (EDX) analysis. The luminescence properties of the phosphors were investigated by thermoluminescence (TL) and photoluminescence (PL). The PL excitation and emission spectra of Ba2MgSi2O7:Eu2+ showed the peak to be around 381 nm and 490 nm respectively. The PL excitation spectrum of Ba2MgSi2O7:Eu2+Dy3+ showed the peak to be around 341 nm and 388 nm, and the emission spectrum had a broad band around 488 nm. These emissions originated from the 4f6 5d1 to 4f7 transition of Eu2+. TL analysis revealed that the maximum TL intensity was found at 5 mol% of Eu2+ doping in Ba2MgSi2O7 phosphors after 15 min of ultraviolet (UV) light exposure. TL intensity was increased when Dy3+ ions were co‐doped in Ba2MgSi2O7:Eu2+ and maximum TL intensity was observed for 2 mol% of Dy3+. TL emission spectra of Ba1.95MgSi2O7:0.05Eu2+ and Ba1.93MgSi2O7:0.05Eu2+,0.02Dy3+ phosphors were found at 500 nm. TL intensity increased with UV exposure time up to 15 min, then decreased for the higher UV radiation dose for both Eu doping and Eu,Dy co‐doping. The trap depths were calculated to be 0.54 eV for Ba1.95MgSi2O7:0.05Eu2+ and 0.54 eV and 0.75 eV for Ba1.93MgSi2O7:0.05Eu2+,0.02Dy3+ phosphors. It was observed that co‐doping with small amounts of Dy3+ enhanced the thermoluminescence properties of Ba2MgSi2O7 phosphor. Copyright © 2016 John Wiley & Sons, Ltd. [Correction added on 5 April 2016, after first online publication: The following parts of the abstract have been edited for consistency. '4f65d1' has been corrected to '4f6 5d1', '4f7' has been corrected to '4f7', 'Ba1.95' has been corrected to 'Ba1.95' and 'Ba1.93' has been corrected to 'Ba1.93' respectively.]  相似文献   

14.
Iron(II)-containing homoprotocatechuate 2,3-dioxygenase (FeHPCD) activates O2 to catalyze the aromatic ring opening of homoprotocatechuate (HPCA). The enzyme requires FeII for catalysis, but MnII can be substituted (MnHPCD) with essentially no change in the steady-state kinetic parameters. Near simultaneous O2 and HPCA activation has been proposed to occur through transfer of an electron or electrons from HPCA to O2 through the divalent metal. In O2 reactions with MnHPCD–HPCA and the 4-nitrocatechol (4NC) complex of the His200Asn (H200N) variant of FeHPCD, this transfer has resulted in the detection of a transient MIII–O2 ·? species that is not observed during turnover of the wild-type FeHPCD. The factors governing formation of the MIII–O2 ·? species are explored here by EPR spectroscopy using MnHPCD and nitric oxide (NO) as an O2 surrogate. Both the HPCA and the dihydroxymandelic substrate complexes of MnHPCD bind NO, thus representing the first reported stable MnNO complexes of a nonheme enzyme. In contrast, the free enzyme, the MnHPCD–4NC complex, and the MnH200N and MnH200Q variants with or without HPCA bound do not bind NO. The MnHPCD–ligand complexes that bind NO are also active in normal O2-linked turnover, whereas the others are inactive. Past studies have shown that FeHPCD and the analogous variants and catecholic ligand complexes all bind NO, and are active in normal turnover. This contrasting behavior may stem from the ability of the enzyme to maintain the approximately 0.8-V difference in the solution redox potentials of FeII and MnII. Owing to the higher potential of Mn, the formation of the NO adduct or the O2 adduct requires both strong charge donation from the bound catecholic ligand and additional stabilization by interaction with the active-site His200. The same nonoptimal electronic and structural forces that prevent NO and O2 binding in MnHPCD variants may lead to inefficient electron transfer from the catecholic substrate to the metal center in variants of FeHPCD during O2-linked turnover. Accordingly, past studies have shown that intermediate FeIII species are observed for these mutant enzymes.  相似文献   

15.
Previously the growth of Spartina alterniflora has been found to be limited by nitrogen and correlated with sediment redox potential. In this study we have investigated a possible connection between these two factors. We have found that internal O2 transport is insufficient to saturate NH4+ uptake in short S. alterniflora in hydroponic culture. Rates of NH4+ uptake and root respiration were very sensitive to O2 concentration in the rhizosphere, saturating at about 5% O2. Ammonium uptake continued at a reduced rate for at least 4 hr under anaerobic conditions. Plant to plant variations in anaerobic rates of NH4+ uptake and root respiration were significantly correlated to the diffusion rate of CH4 tracer gas from the leaves to the roots of individual plants.  相似文献   

16.
Two previously unknown resveratrol trimers named wilsonols A–B, as well as a resveratrol tetramer named wilsonol C, were isolated from Vitis wilsonae Veitch, together with 12 known oligostilbenes. Their chemical structures have been elucidated by detailed analyses of 1D and 2D NMR spectroscopic data, as well as chemical evidence obtained via either catalysis with HRP (horseradish peroxidase) and H2O2 (hydrogen peroxide), acid, or UV irradiation. During the chemical processes, a biomimetic resveratrol tetramer named diviniferin B that has not been found in nature was obtained. These oligostilbenes showed potent scavenging abilities towards DPPH radicals and selective quenching effects on 1O2 radicals. Furthermore, the biogenetic transformations between the 16 oligostilbenes have been elaborated chemically to provide a comprehensive mechanism of the antioxidative defense system in this plant species.  相似文献   

17.
H2–forming N 5,N 10 methylenetetrahydromethanopterin dehydrogenase is a novel type of hydrogenase that contains neither nickel nor iron-sulfur clusters. Evidence has been presented that the reaction mechanism catalyzed by the enzyme is very similar to that of the formation of carbocations and H2 from alkanes under superacidic conditions. We present here further results in support of this mechanism. It was found that the purified enzyme per se did not catalyze the conversion of para H2 to ortho H2, a reaction catalyzed by all other hydrogenases known to date. However, it catalyzed the conversion in the presence of the substrate N 5,N 10 methenyltetrahydromethanopterin (CH≡H4MPT+), indicating that for heterolytic cleavage of H2 the enzyme-CH≡H4MPT+ complex is required. In D2O, the formation of HD and D2 from H2 rather than a paraortho H2 conversion was observed, indicating that after heterolytic cleavage of H2 the dissociation of the proton from the enzyme-substrate complex is fast relative to the re-formation of free H2.  相似文献   

18.
Hydrogen peroxide is the most stable of the reactive oxygen species (ROS) and is a regulator of development, immunity and adaptation to stress. It frequently acts by elevating cytosolic free Ca2+ ([Ca2+]cyt) as a second messenger, with activation of plasma membrane Ca2+‐permeable influx channels as a fundamental part of this process. At the genetic level, to date only the Ca2+‐permeable Stelar K+ Outward Rectifier (SKOR) channel has been identified as being responsive to hydrogen peroxide. We show here that the ROS‐regulated Ca2+ transport protein Annexin 1 in Arabidopsis thaliana (AtANN1) is involved in regulating the root epidermal [Ca2+]cyt response to stress levels of extracellular hydrogen peroxide. Peroxide‐stimulated [Ca2+]cyt elevation (determined using aequorin luminometry) was aberrant in roots and root epidermal protoplasts of the Atann1 knockout mutant. Similarly, peroxide‐stimulated net Ca2+ influx and K+ efflux were aberrant in Atann1 root mature epidermis, determined using extracellular vibrating ion‐selective microelectrodes. Peroxide induction of GSTU1 (Glutathione‐S‐Transferase1 Tau 1), which is known to be [Ca2+]cyt‐dependent was impaired in mutant roots, consistent with a lesion in signalling. Expression of AtANN1 in roots was suppressed by peroxide, consistent with the need to restrict further Ca2+ influx. Differential regulation of annexin expression was evident, with AtANN2 down‐regulation but up‐regulation of AtANN3 and AtANN4. Overall the results point to involvement of AtANN1 in shaping the root peroxide‐induced [Ca2+]cyt signature and downstream signalling.  相似文献   

19.
Using a high‐temperature solid‐state reaction, the chlorine in Ba2YB2O6Cl is gradually replaced by F, and a new compound with the nominal chemical formula Ba2YB2O6F and two phosphors doped with Ce3+ and Eu3+, respectively, are obtained. X‐Ray diffraction and photoluminescence spectroscopy are used to characterize the as‐synthesized samples. The as‐synthesized Ba2YB2O6Cl exhibits bright blue emission in the spectral range ~ 330–410 nm with a maximum around 363 nm under X‐ray or UV excitation. Ba2YB2O6F:0.01Ce3+ exhibits blue emission in the range ~ 340–570 nm with a maximum around 383 nm. Ba2YB2O6F:0.01Eu3+ exhibits a predominantly 5D07 F2 emission (~610 nm) and the relative intensities of the 5D07 F0,1,2 emissions are tunable under different wavelength UV excitation. The luminescence behaviors of the two phosphors are explained simply in terms of the host composition and site occupancy probability of Ce3+ and Eu3+, respectively. The results indicate that these phosphors have potential application as a blue phosphor or as a red phosphor. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

20.
CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors were synthesized using the solid‐state reaction method. X‐Ray diffraction (XRD) and photoluminescence (PL) analyses were used to characterize the phosphors. The XRD results revealed that the synthesized CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors were crystalline and are assigned to the monoclinic structure with a space group C2/c. The calculated crystal sizes of CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors with a main (221) diffraction peak were 44.87 and 53.51 nm, respectively. Energy‐dispersive X‐ray spectroscopy (EDX) confirmed the proper preparation of the sample. The PL emission spectra of CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors have a broad band peak at 444.5 and 466 nm, respectively, which is due to electronic transition from 4f65d1 to 4f7. The afterglow results indicate that the CaMgSi2O6:Eu2+,Dy3+ phosphor has better persistence luminescence than the CaMgSi2O6:Eu2+,Ce3+ phosphor. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号