Electronic Bridge Research Articles

Excitation of the low-energy Th229m isomer in the electron bridge process via the continuum

The paper studies the excitation of the $^{229}\mathrm{Th}$ nucleus to the anomalously low-lying isomeric state $3/{2}^{+}(8.28\ifmmode\pm\else\textpm\fi{}0.17$ eV) in the electron bridge process via the continuum of the electron spectrum. Resonant excitation of the nucleus was found to be always possible in the scheme, no matter where the electron levels of an atom or ion were located. Formulas for the excitation cross section by narrow and wide laser lines are obtained. In the resonance, where the process under consideration turns into laser photoionization followed by nuclear excitation in electron capture, the cross section of the process was shown to be comparable in magnitude with that of the photoionization of the thorium atom. Experimental schemes for testing the effect were proposed, which would allow measuring the frequency of the nuclear isomeric transition $3/{2}^{+}\ensuremath{\rightarrow}5/{2}^{+}$ to a high precision, which is the first-priority (and still unresolved) task for creating a nuclear clock.

Improved biogas production of dry anaerobic digestion of swine manure

In this work, wrapped granular activated carbon (GAC) and acclimated sludge were employed to enhance the efficiency of the dry anaerobic digestion of swine manure in semi-continuous tests. The addition of wrapped GAC increased the volumetric biogas production rate by 10.6%, and the removal efficiencies of TS and VS were enhanced by 5.3% and 6.6%, respectively. The concentration of total volatile fatty acids (TVFA) was 30.3% lower in the GAC reactor, but the total ammonia nitrogen (TAN) content was 15.3% higher. Inoculating with acclimated sludge helped the system survive unfavorable conditions, where the TAN and TVFA contents were around 5,200 mg/L and 8,800 mg/L, respectively, but it failed to improve the biogas production efficiency. The mechanisms that allowed GAC to increase the production of biogas were related to the improved hydrolysis process, enhanced microbial adhesion, the provision of electronic bridges, and enrichment of functional microorganism.

Light harvesting and photo-induced electrochemical devices based on bionanocage proteins

In this study, bionanoferritin based Fe and Mn having nanocages, FeMnFBNC's, have adsorbed onto the immobilized graphene surface by electrostatic bonding. This immobilization enhances the capability of electron transfer between the bionanoferritin layer and graphene surface owing to the well-designed robust bionanocage structure. FeMnFBNCs have electronic bridges that consist of some tyrosine and ferritin amino acid residues with visible light photocrosslinking system between iron and manganese metals, which are capable of electron transfer that allows designing electrochemical and energy harvesting devices. Additionally, a novel hybrid and self-assembly bio-dye-approach as a new generation of dye-sensitized solar cells has been developed. Bionanoferritin/graphene/TiO2 based Bio-N-DSSC molecules can provide an intriguing alternative to traditional materials utilized in dye-sensitized solar cells.

Effect of Triethanolamine as a New and Efficient Additive on Thiosulfate-Copper-Ammonia System Leaching of Gold

A new and efficient additive, triethanolamine (TEA), was used on pure gold leaching in a thiosulfate-copper-ammonia system. An appropriate TEA concentration enhanced the gold dissolution rate and reduced thiosulfate consumption. The beneficial effect became most pronounced in the case of MTEA:Mcopper = 1:1, where the gold dissolution rate increased by approximately 50% and thiosulfate consumption decreased by approximately 10%. The possible mechanisms of TEA are as follows: TEA combines with cupric and ammonia, which enhances the catalytic oxidation ability of Cu(II). Meanwhile, TEA can reduce the consumption of thiosulfate caused by the oxidation of Cu(II) and hence decreases the formation of passivation layers on the gold surface. Furthermore, the deprotonated ethanolic oxygen atoms of [Cu(NH3)x(TEA)y] act as bridging ligands, which could form an “electronic bridge” that benefits the electron transfer from Au0 to Cu2+. In addition, the actual main reaction complex in the cupric-ammonia-TEA complex ([Cu(NH3)x(TEA)y]) was [Cu(NH3)3TEA]2+.

Engineering the performance of heterogeneous WO3/fullerene@Ni3B/Ni(OH)2 Photocatalysts for Hydrogen Generation

The hydrogen production through solar water splitting could be eco-friendly, environmental-benign and sustainable, alternative to fossil fuels energy carriers. In this work, the novel heterojunction WO3/fullerene/Ni3B/Ni(OH)2 composites were successfully fabricated through different methods. The Ni3B/Ni(OH)2 as a needle like nanostructures were integrated into the interfaces between WO3 and fullerene. The structural phase and morphology of prepared nanomaterials were significantly modified by incorporating the Ni3B/Ni(OH)2 as a co-catalyst. The results demonstrated that dopant element serves as the conductive electron bridges, rather than general cocatalyst, to accumulate electrons and inspire the H2 generation kinetics over pure WO3 photocatalyst. The significantly improved hydrogen rate of evolution up to 1578 μmol h−1 g−1 was found for hybrid photocatalyst [WO3/fullerene@ 1.5% Ni3B/Ni(OH)2] which was 9.6 times higher as compared to pure photocatalyst. The interfacial contact between co-catalyst and composite could play substantial role in effective separation and transference of charge-carriers for improved hydrogen evolution rate. Under the visible light illumination, the heterojunction nanostructures inspire rapid transfer of electrons from WO3 towards Ni3B/Ni(OH)2 to inhibit the fast recombination rate and prolong the WO3 charge-carrier's lifetime, thereby releasing more electrons with greater reducing power for hydrogen production. This work may open an avenue for the strategy and green preparation of robust photocatalysts for scalable applications in solar H2 evolution and sustainable environment.

Bidirectional electron transfer biofilm assisted complete bioelectrochemical denitrification process

The biocathode of microbial electrochemical system (MES) accomplished bioelectrochemical denitrification in low C/N wastewater with low demand of exogenous electron donor. However, nitrite accumulation limited the overall nitrogen removal and challenged the further application of bioelectrochemical denitrification process. In this study, a bidirectional electron transfer cathodic biofilm dominated by Geobacter sp. was obtained by polarity reversion from anode to achieve complete nitrogen removal of 98 ± 1.2% (R1), where the Geobacter sp. was sustained by adding 0.1 g L–1 sodium acetate. However, in autotrophic circumstance after electrode reversal, the Geobacter sp. in cathodic biofilm (R2) rapidly lost along with a remarkable drop of nitrogen removal from 76 ± 8.7% (R2-S) to 47 ± 6.6% (R2-1M). Directly domesticated denitrifying biocathode (R3) obtained the lowest total nitrogen removal of 7 ± 3.8%. From principal co-ordinates analysis (PCoA), the function and bio-community of R1 and R2-S demonstrated high similarity with those of anode, while that of R2-1M were much similar with that of R3. The non-turnover CV and DPV indicated that electrochemical active bacteria, such as Geobacter sp., lasted from anode sustained functioning in biofilm of R1, which acted as “electron bridge” to provide extra access for denitrifiers to get electrons from cathode. The mediated electron transfer (MET) was considered as the main mechanism in this “electrode–to–cell–to–cell” pathway by CV analyses with different scan rates.

Electronic level structure of Th+ in the range of the Th229m isomer energy

Using resonant two-step laser excitation of trapped $^{232}\mathrm{Th}^+$ ions, we observe 166 previously unknown energy levels of even parity within the energy range from 7.8 to 9.8 eV and angular momenta from $J=1/2$ to $7/2$. We also classify the high-lying levels observed in our earlier experiments by the total angular momentum and perform ab-initio calculations to compare their results with the observed level density. The observed levels can be relevant for the excitation or decay of the $^{229m}\mathrm{Th}$ isomeric nuclear state which lies in this energy range. The high density of electronic levels promises a strongly enhanced electronic bridge excitation of the isomer in $^{229}\mathrm{Th}^+$.

To what extent are the photophysical properties of quinoxaline- and quinoxalinone-based chromophores predictable?

A series of chromophores containing quinoxaline or quinoxalinone electron-acceptor (A) and dialkylaminostyryl electron-donor (D) units linked by π electronic bridge has been synthesized. Electronic emission and absorption spectra of the novel D-π-A, D-π-A-π-D or D-π-A-π-A-π-D systems cover a broad range from ultraviolet to near infrared. Positions and relative intensities of their absorption bands are shown to depend strongly on structural modifications of the molecules, while emission in solution strongly depends on both the structure of the solute and the solvent polarity. Quantum chemical modeling provided a reliable description of the observed absorption spectra and reproduced the positions of the emission bands. Quantum yields of emission are shown to be qualitatively predictable on the basis of empirical rules connecting the luminescence intensity with the chemical structures of both quinoxaline- and quinoxalinone-based luminopohores and the polarity of the solvents used. Theoretical assessment of the character of the main electronic transitions suggests that simultaneous presence of D and A units conjugated via π-bridges ensures the intramolecular charge-transfer effects probably underlying the observed similar solvatochromism for all the studied systems irrespective of their polarity.

Stochastic mechanics for ponderomotive effect of a spin-less electron interacting with a high-intensity plane wave laser field

We discuss the relativistically covariant ponderomotive effect of a spin-less electron by a high-intensity laser field of a plane wave in the quantum regime. At first we recall the relativistic ponderomotive effect in classical mechanics. Then against that, we will investigate quantum mechanical expression of the ponderomotive effect by relativistic stochastic mechanics, where, we also propose relativistic stochastic mechanics to draw a trajectory of a spin-less electron. After giving a strict solution of stochastic mechanics, its slowly varying motion is examined as its ponderomotive effect in the quantum regime. Finally, we will see the universality of the ponderomotive effect acting on a spin-less electron interacting with a present high-intensity femtosecond laser, via the dressed (effective) mass of a spin-less electron bridging between classical and quantum mechanics.

Engineering MPx (M = Fe, Co or Ni) interface electron transfer channels for boosting photocatalytic H2 evolution over g-C3N4/MoS2 layered heterojunctions

It is challenging to develop highly efficient, multifunctional and low-cost cocatalysts to accelerate transfer, separation and utilization of charge carriers for fundamentally boosting photocatalytic H2 evolution. So far, the famous metallic MPx (M = Fe, Co or Ni) H2-evolution cocatalyst have never been used as interface electron transfer channels between semiconductors and cocatalysts. Herein, we, for the first time, demonstrated that metal phosphide (MP) cocatalyts could be used as an interface electronic bridge to greatly enhance the photocatalytic H2 evolution over 2D/2D g-C3N4/MoS2 layered heterojunctions. The results clearly prove that Ni2P could serve as much better interface electron transfer channel than CoP and Fe2P. The highest hydrogen production rate of ternary g-C3N4-1%Ni2P-1.5%MoS2 could reach 532.41 μmolg−1h−1, which was 2.47 and 5.15 times than those of g-C3N4-1.5%MoS2 and g-C3N4-1%Ni2P, respectively. More importantly, the bi-functional roles of MP cocatalyts in boosting photocatalytic H2 evolution were also carefully revealed. Apparently, the metallic MP cocatalyts could not only serve as normal cocatalysts to boost the H2-evolution kinetics through decreasing the overpotential, but also can act as excellent interface electron transfer channels to achieve efficient transfer of more electrons from g-C3N4 to the surface active sites of MoS2, thus synergistically leading to the significantly boosted H2 evolution. This work would open up opportunities to develop high-efficiency and low-cost photocatalytic system using the rationally designed metallic earth-abundant cocatalysts as the interface electron bridge.

Tetracycline degradation by persulfate activated with magnetic Cu/CuFe2O4 composite: Efficiency, stability, mechanism and degradation pathway.

Magnetically separable Cu/CuFe2O4 composite obtained by a solvothermal method was used to active persulfate (PS) for the removal of tetracycline (TC). Under different pH conditions, Cu/CuFe2O4 catalyst exhibited a higher catalytic activity for PS activation to degrade TC than that of CuFe2O4. The effects of some key parameters including initial pH value, PS concentration, catalyst dosage, reaction temperature and coexisting ions on TC degradation were investigated in Cu/CuFe2O4/PS system. The reuse of Cu/CuFe2O4 catalyst at pH 3.50, 7.00 and 11.00 indicated that the catalyst showed a low stability due to the corrosion of metallic copper (Cu°), but bicarbonate ions could enhance the stability and recyclability of this catalyst through the suppression of copper leaching. Both sulfate and hydroxyl radicals were the main reactive species in Cu/CuFe2O4/PS system. Cu° can not only work as electron donor to active PS to produce the reactive radicals but also act as an electron bridge to facilitate the fast electron transfer between PS and catalyst. The structural cuprous and ferrous ions on the surface of CuFe2O4 participated in the PS activation process through the redox reactions, as confirmed by XPS analysis. The possible degradation pathways of TC were proposed based on the identified intermediates.

Establishing a Ventilator–Heart Lung Machine Communication Bridge to Mitigate Errors when Weaning from Bypass

If a perfusionist weans a patient off the heart lung machine (HLM) and the anesthesiologist has not re-started the ventilator, the patient will become hypoxic. The objective of this project was to create a redundant safety system of verbal and electronic communication to prevent failure to ventilate errors after cardiopulmonary bypass. This objective could be realized by building an electronic communication bridge directly between the HLM and ventilator. A software application was created to retrieve and interpret data from the pump and ventilator and trigger a programmed smart alarm. The software is able to interpret data from the pump and ventilator. When both are off simultaneously (defined as a pump flow of 0 L/min with a respiratory rate of 0 breaths/min), the application will raies an alarm. Communication between a pump and ventilator is possible, enabling the deployment of a safety system that could exist in the operating room (OR) as a standalone alarm. A device dataset can be used to optimize clinical performance of the alarm. The application could also be integrated into smart checklists and computer-assisted OR process models that are currently in development.

Sandwich-Type Si@C/rGO Composite Stabilized by Polyetherimide-Derived Interface with Efficient Lithium Storage and High Rate Performance

The essential characteristics between highest theoretic capacity and intrinsic volumetric changes hinders the applicable development of Si on high energy/power lithium ion batteries. A novel strategy of building moderate interface linkage combined with preferential three-dimensional structure is put forward by anchoring silicon to conductive matrix by controllable conjugated polar interaction and functional group interaction in our study. A sandwich Si-containing composite of Si@C/rGO with robust polyetherimide “Electron Bridges” is obtained. Polyetherimide is strategically introduced as electron bridges and cross links between conductive matrix and Si nanoparticles with the formation of carbon nanoshell and controllable interface linkage. Beneficially, the architecture effectively provides more electron channels to maintain electrical connectivity, and alleviates the structure collapse to ensure the utilization and the stabilization of silicon materials. This Si@C/rGO anode material exhibits excellent cycling performance with a high reversible capacity of 2048.7 mAh g−1 after 100 cycles. The Coulombic efficiency approaches to 99.8%, and the average capacity loss is only 0.103% per cycle over 500 cycles at 5 C. The optimized confluence of robust interface bonding, stable mechanical structure and excellent electronic connectivity provides a feasible strategy to obtain ultra-long-life silicon anode materials.

Large Kondo effect in assemblies of Au nanoparticles linked with alkanedithiol electron bridges.

Using a prototypical nanoparticle-molecule assembly, namely alkanedithiol-linked gold nanoparticle films, we observe hallmark signatures of the Kondo effect in conductance vs. voltage as well as temperature measurements. Its contribution to temperature dependence of conductance is much larger than those from all other temperature-dependant effects up to 300 K by >20-fold - much larger than previous reports of the Kondo effect using other platforms. We find that previous models of the Kondo effect describe our data even in this regime. Given the synthetic control available over nanoparticle properties such as surface area, shape, and chemical composition, our work points to combining flexibility afforded by molecule + nanoparticle assemblies as a powerful way to generate materials exhibiting strong spin-electron interactions.

Resonant Electronic-Bridge Excitation of the ^{235}U Nuclear Transition in Ions with Chaotic Spectra.

Electronic-bridge excitation of the 76eV nuclear isomeric state in ^{235}U is shown to be strongly enhanced in the U^{7+} ion, potentially enabling laser excitation of this nucleus. This is because the electronic spectrum has a very high level density near the nuclear transition energy that ensures the resonance condition is fulfilled. We present a quantum statistical theory based on many-body quantum chaos to demonstrate that typical values for the electronic factor increase the probability of electronic bridge in ^{235}U^{7+} by many orders of magnitude. We also extract the nuclear matrix element by considering internal conversion from neutral uranium. The final electronic-bridge rate is comparable to the rate of the Yb^{+} octupole transition currently used in precision spectroscopy.

Fabrication of heterogeneous photocatalysts for insight role of carbon nanofibre in hierarchical WO3/ MoSe2 composite for enhanced photocatalytic hydrogen generation

Mimicking the natural photosynthesis system, artificial photocatalysis facilitates effective utilization of solar energy for environmental sustainability and hydrogen energy production. In this work, the robust and efficient carbon fiber has been successfully incorporated into the interface between WO3 nanodots and MoSe2 needles using the facile hydrothermal and solvothermal method. The suitable interfacial contact of heterogeneous photocatalysts plays a significant role in the separation/transfer of interfacial photogenerated electron-hole pairs and hetero-junction. It seems an efficient approach for enhanced photocatalytic performance since the greater area of contact could improve the interfacial rate of charge transfer. The phase structure of prepared WO3 nanodots changed from the monoclinic to hexagonal phase by the addition of co-catalyst. The experimental results exhibited that carbon fiber played a tri-functional role to boost up the photocatalytic activity over MoSe2 nanostructures. It's not only act as operative co-catalyst but could also serve as the conductive electron bridges, rather than general cocatalyst, to accumulate electrons and encourage the hydrogen generation kinetics over the WO3 photocatalysts. More interestingly, the WO3−1% MoSe2−1.5% carbon fiber and WO3−1%MoSe2 nanocomposites demonstrated the excellent rates of hydrogen evolution 438.7 and 356.2 mmol/g.h, which were 7.6 and 6.17 times higher when compared to that of pure MoSe2, respectively. Under the visible light excitation, the atomically junction encourages fast electron transfer from nanofibers to MoSe2 to suppress the rapid recombination kinetics within WO3 nanodots and extend the lifetime of WO3 charge carrier's, thereby releasing more photogenerated electrons with higher reducing power for hydrogen evolution. The current work can contribute with new perspectives and mechanistic insight for the design and development of heterogeneous photocatalysts WO3 based nanostructures using the combination of MoSe2 and trifunctional carbon nanofibers for environment and energy harvesting applications.

An electron bridge in place of a ferry

Structural Biology Respiratory complexes are massive, membrane-embedded scaffolds that position redox cofactors so as to permit electron transfer coupled to the movement of protons across a membrane. Gong et al. used cryo–electron microscopy to determine a structure of a stable assembly of mycobacterial complex III–IV, in which a complex III dimer is sandwiched between two complex IV monomers. A potential direct electron transfer path stretches from the quinone oxidizing centers in complex III to the oxygen reduction centers in complex IV. A loosely associated superoxide dismutase may play a role in detoxifying superoxide produced from uncoupled oxygen reduction. Science , this issue p. [eaat8923][1] [1]: /lookup/doi/10.1126/science.aat8923

Copper phosphide and persulfate salt: A novel catalytic system for the degradation of aqueous phase micro-contaminants

The heterogeneous activation of sodium persulfate (SPS) using copper (I) phosphide (Cu3P) nanoparticles was tested in this work. The catalyst was synthesized via a two-step method involving preparation of Cu(OH)2 and subsequent low temperature phosphidation and characterized with BET, XRD, TEM/HRTEM, SEM and XPS techniques. The XRD pattern showed the existence of hexagonal Cu3P phase with mean primary crystallite size of ca. 28 nm. The XP spectra indicated the presence of residual Cu(OH)2 and Cu3(PO4)2 species on the catalyst surface, originating from the synthesis methods employed, which disappeared after exposure to reaction conditions.The activity of Cu3P was evaluated for the degradation of antibiotic sulfamethoxazole (SMX), which occurred in short reaction times. The effect of catalyst concentration (20–80 mg/L), SPS dosage (0.05–1 g/L) and SMX concentration (0.5–4.1 mg/L) on degradation was studied. Results obtained in ultrapure water (UPW) showed that SMX degradation increases with increasing catalyst content in the range 20–80 mg/L and SPS concentration in the range 0.05–0.5 g/L. In contrast, increasing SPS concentration at 1 g/L leads to lower reaction rates. Experiments were also conducted in bottled water, secondary treated wastewater, UPW spiked with bicarbonate or chloride ions, as well as UPW containing humic acid. With the use of t-butanol and methanol as radical quenching agents, SO4•- was found to be the primary radical species responsible for SMX degradation. The simultaneous use of Cu3P and solar irradiation as persulfate activators resulted in a synergistic effect in experiments performed in UPW and wastewater.From a mechanistic point of view, Cu3P acts as an electron mediator or bridge to facilitate the electron-transfer processes and this is accompanied by the intermediate formation of radicals. The catalyst remains intact, thus implying the catalytic nature of the process.

Ternary assembly of g-C3N4/graphene oxide sheets /BiFeO3 heterojunction with enhanced photoreduction of Cr(VI) under visible-light irradiation

A novel ternary composite of graphitic carbon nitride (g-C3N4)/graphene oxide (GO) sheets/BiFeO3 (CNGB) with highly enhanced visible-light photocatalytic activity toward Cr(VI) photoreduction is prepared and characterized. The characterization and photocatalysis experiments corroborate its reasonable band gap, efficient charge separation and transfer, widened visible-light adsorption, easy solid-liquid separation, good stability and superior catalytic activity of CNGB. Three CNGB samples with different ratios of g-C3N4 and BiFeO3 (CNGB-1, -2, -3 with 2:4, 3:3, and 4:2, respectively), though possessing different adsorption ability, eventually remove all Cr(VI) ions via photocatalysis within 90 min. The catalytic efficiency of the composite is the highest at pH 2; increases in pH decrease the catalytic ability. The inorganic anions such as SO4−, Cl−, and NO3− only slightly affects the photocatalytic process. The matching of the band structure between BiFeO3 and g-C3N4 generates efficient photogenerated electron migration from the conduction band of g-C3N4 to that of BiFeO3, which is also facilitated by the electron bridging and collecting effects of GO, and holes transfer from the valence band of BiFeO3 to that of g-C3N4, yielding the efficient separation of photogenerated electron-hole pairs and the subsequent enhancement of photocatalytic activity. The research provides a theoretical basis and technical support for the development of photocatalytic technologies for effective application in wastewater treatment and Cr-contaminated water restoration.

Electron bridging structure glued yolk-shell hierarchical porous carbon/sulfur composite for high performance Li-S batteries

Despite various carbon materials have been extensively applied in lithium-sulfur (Li-S) battery, efficient optimization of the material structure for further performance improvement is remaining a great challenge. Herein, we fabricated electron bridging structure glued yolk-shell hierarchical porous carbon (HPC) nanospheres containing a microporous shell and a mesoporous core as cathode host for Li-S battery. In which, the inner mesoporous core acts as a sulfur reservoir to entrap polysulfide species, and the outer micropores shell provides not only large contact area between sulfur and conductive substrate, but also physical confinement and chemical adsorption to trap polysulfide. This yolk-shell HPC was further glued by an electron bridging structure consisting of carbon nanotube (CNT) decorated polyaniline (PANi), who can further suppress the shuttle effect benefit from PANi and afford a highly conductive network by affording a “point-to-plane” type electron transport mode instead of the “point-to-point”. As a result, this designed cathode material exhibits a high initial specific capacity of 1372 mAh g−1 at 0.2 A g−1, and excellent cycling stability with a capacity decay of 0.083% per cycle over 500 cycles at 2 A g−1. This strategy provides a promising approach for the design of multifunctional carbon materials for high performance Li-S batteries.