Evolution Of Coupling Research Articles

Evolution of internal dimensions in object‐oriented software–A time series based approach

SummarySoftware evolution is the process of adapting, maintaining, and updating a software system. This process concentrates the most significant part of the software costs. Many works have studied software evolution and found relevant insights, such as Lehman's laws. However, there is a gap in how software systems evolve from an internal dimensions point of view. For instance, the literature has indicated how systems grow, for example, linearly, sub‐linearly, super‐linearly, or following the Pareto distribution. However, a well‐defined pattern of how this phenomenon occurs has not been established. This work aims to define a novel method to analyze and predict software evolution. We based our strategy on time series analysis, linear regression techniques, and trend tests. In this study, we applied the proposed model to investigate how the internal structure of object‐oriented software systems evolves in terms of four dimensions: coupling, inheritance hierarchy, cohesion, and class size. Applying the proposed method, we identify the functions that better explain how the analyzed dimensions evolve. Besides, we investigate how the relationship between dimension metrics behave over the systems' evolution and the set of classes existing in the systems that affect the evolution of these dimensions. We mined and analyzed data from 46 Java‐based open‐source projects. We used eight software metrics regarding the dimensions analyzed in this study. The main results of this study reveal ten software evolution properties, among them: coupling, cohesion, and inheritance evolve linearly; a relevant percentage of classes contributes to coupling and size evolution; a small percentage of classes contributes to cohesion evolution; there is no relation between the software internal dimensions' evolution. The results also indicate that our method can accurately predict how the software system will evolve in short‐term and long‐term predictions.

An Evaluation and Difference Analysis of the High-Quality Development of China’s Marine Economy

The marine economy is a vital component of boosting the high-quality development of the Chinese economy. According to the concept of high-quality development, we construct the evaluation indicator system to measure the level of high-quality development of the marine economy by means of the combined empowerment method. We explore the coupling coordination relationship and evolution trend with the coupling coordination degree model, and finally, we analyze the regional differences using the Dagum Gini coefficient. The results show that, (1) from the perspective of time, China’s marine economic high-quality development index has been steadily improving, but there is still great potential for progress. From the perspective of spatial characteristics, the eastern marine economic circle has the best level of high-quality economic development. (2) From 2012 to 2022, the coupling coordination degree of high-quality development of the marine economy experienced five stages, from the verge of disorder to finally stepping into the good coupling coordination stage. (3) The overall difference in the marine economy is gradually narrowing. Among the three major marine economic circles, the southern marine economic circle has the largest internal discrepancy, which has become an important factor affecting the high-quality development of the marine economy. The above research results helped relevant decision-making departments to deeply understand the status quo and outstanding contradictions of the high-quality development of the marine economy in China.

On Two Types of Stability of Solutions to a Pair of Damped Coupled Nonlinear Evolution Equations

On Two Types of Stability of Solutions to a Pair of Damped Coupled Nonlinear Evolution Equations

Dynamic Coupling and Coordinated Evolution of Rural Tourism Development and Cultural Industry in the Information Age

Abstract This paper selects rural tourism development indicators and cultural industry development indicators, respectively, and constructs the evaluation system of comprehensive development level of rural tourism development and cultural industry. The dynamic coupling evolution algorithm is proposed, algorithm improvement is carried out, and the improved coupling model is used to substitute rural tourism development and cultural industry development to analyze the dynamic coordination evolution of the two. Use hierarchical analysis to calculate the weights of the indicator system. Combined with the comprehensive development level of rural tourism and the comprehensive development level of the cultural industry, the coupling and coordination level of the two are measured, and suggestions for the integrated development of rural culture and tourism are put forward. By 2020, the coupling coordination degree of the cultural industry and rural tourism industry in L city will develop to 0.734, and both the cultural industry and rural tourism industry will reach the intermediate level of coordination, but the development of the tourism industry is relatively lagging, and the comprehensive development level of the cultural industry will be 0.695, and the comprehensive development level of tourism industry will be 0.562.

Spatial–Temporal Evolution of Coupling Coordination Development between Regional Highway Transportation and New Urbanization: A Case Study of Heilongjiang, China

The coupling coordination relationship between regional highway transportation and new urbanization is an increasingly important issue in the field of regional sustainable development. This paper aims to establish an index system and develop an integrated method to measure the coupling coordination between regional highway transportation and new urbanization. The evaluation index system comprised two hierarchies, six aspects and 19 indexes, which were weighted by the entropy weight method (EWM). Furthermore, a coupling degree model (CDM) and a coupling coordination degree model (CCDM) were established based on the statistical data from 2011 to 2017 in Heilongjiang Province, China. The ArcGIS spatial analysis method was utilized to analyze the spatial–temporal coupling evolution characteristics of the two subsystems. The findings revealed that the development level of the two subsystems showed an upward tendency. The coupling degree between the two subsystems was leaping from antagonistic stage to breaking-in period. The coupling coordination degree between the two subsystems was the transition stage from imbalance to coordination. Specifically, the spatial differentiation characteristics of the coupling coordination development between the two subsystems were prominent in Heilongjiang Province, China. The results showed that the approach combining CCDM with ArcGIS spatial analysis can be applied as an effective method to explore the spatial–temporal evolution of coupling coordination development.

Renormalisation group analysis of scalar Leptoquark couplings addressing flavour anomalies: emergence of lepton-flavour universality

Leptoquarks with masses between 2 TeV and 50 TeV are commonly invoked to explain deviations between data and Standard-Model (SM) predictions of several observables in the decays b→cτν¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ b\ o c\ au \\overline{\ u} $$\\end{document} and b → sℓ+ℓ− with ℓ = e, μ. While Leptoquarks appear in theories unifying quarks and leptons, the corresponding unification scale MQLU is typically many orders of magnitude above this mass range. We study the case that the mass gap between the electroweak scale and MQLU is only populated by scalar Leptoquarks and SM particles, restricting ourselves to scenarios addressing the mentioned flavour anomalies, and determine the renormalisation-group evolution of Leptoquark couplings to fermions below MQLU. In the most general case, we consider three SU(2) triplet Leptoquarks S3ℓ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {S}_3^{\\ell } $$\\end{document}, ℓ = e, μ, τ, which couple quark doublets to the lepton doublet (νℓ, ℓ−) to address the b → sℓ+ℓ− anomalies. In this case, we find a scenario in which the Leptoquark couplings to electrons and muons are driven to the same infrared fixed point, so that lepton flavour universality emerges dynamically. However, the corresponding fixed point for the couplings to taus is necessarily opposite in sign, leading to a unique signature in b → sτ+τ−. For b→cτν¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ b\ o c\ au \\overline{\ u} $$\\end{document} we complement these with either an SU(2) singlet S1τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {S}_1^{\ au } $$\\end{document} or doublet R2τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {R}_2^{\ au } $$\\end{document} and study further the cases that also these Leptoquarks come in three replicas. The fixed point solutions for the S3ℓ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {S}_3^{\\ell } $$\\end{document} couplings explain the b → sℓ+ℓ− data for S3e,μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {S}_3^{e,\\mu } $$\\end{document} masses between 14 and 15 TeV, according to the scenario. b→cτν¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ b\ o c\ au \\overline{\ u} $$\\end{document} data can only be fully explained by couplings exceeding their fixed-point values and evolving into Landau poles at high energies, so that one can place an upper bound on MQLU between 108 and 1011 GeV.

Iodine‐Mediated C─C Coupling in Neutral Flow Cell for Electrochemical CO2 Reduction

AbstractCarbon utilization efficiency is of vital importance for electrochemical CO2 reduction systems. Proton exchange membrane (PEM) electrolyzers using nonalkaline electrolytes can prevent CO2 crossover and increase carbon utilization efficiency, yet they suffer from unfavored C─C coupling and severe hydrogen evolution. Herein, an iodine‐mediated approach to facilitate C─C coupling on Cu‐based catalysts toward multi‐carbon products in a neutral PEM electrolyzer is reported. By in situ constructing an I‐modified Cu surface, the hydrogenation of *CO is promoted and the C─C coupling process progresses through the *CO−*COH pathway with a low energy barrier. A high Faradaic efficiency of ≈72% and a high partial current density of 575 mA cm−2 are achieved for multi‐carbon products. The present study demonstrates an efficient approach to developing advanced CO2 electrolyzers for high‐value products with high efficiency.

Effect of dimensionless vent ratio on the flame-shock wave evolution dynamics of blended LPG/DME gas explosion venting

To reveal the flow field-shock wave-flame coupling evolution law of LPG/DME blended gas explosion venting under different dimensionless vent ratio(KV), the numerical model for multi-blended gas explosion venting was established and research of blended gas explosion venting at KV = 0.02–0.21 was carried out based on experimental verification. The results show that, after the vent opens, the turbulence intensity increases, the velocity gradient of the flow field increases, the maximum explosion wind velocity(Vmax) of the outfield varies linearly with KV, and the flame of “mushroom shape” is elongated, and “break flame” occurs under the action of the relative motion of “primary and secondary vortex group”. When KV＞0.02, the flame propagation velocity increases locally because of the thermal-mass diffusion instability, and with increasing KV, the average flame propagation velocity decreases from 258.29 m/s to 226.58 m/s. In the process of explosion venting, a typical shock wave fluctuating pressure waveform curve is formed in the outfield. Under the combined action of the infield pressure venting effect and the outfield turbulence intensity, the maximum explosion overpressure in the outfield (Pmax) reaches maximum 423.97 kPa at KV = 0.07. Meanwhile, the larger the KV, the greater the shock wave velocity due to the lead role of the infield explosion venting shock wave and outfield flame compression shock wave on the shock wave propagation velocity.

Large interlayer Dzyaloshinskii-Moriya interactions across Ag-layers

Seeking to enhance the strength of the interlayer Dzyaloshinskii-Moriya interaction (IL-DMI) through a combination of atomic and Rashba type spin-orbit coupling (SOC) we studied the strength and the thickness evolution of effective interlayer coupling in Co/Ag/Co trilayers by means of surface sensitive magneto-optical measurements that take advantage of the light penetration depth. Here, we report the observation of oscillatory, thickness-dependent chiral interaction between ferromagnetic layers. Despite the weakness of the Ag atomic SOC, the IL-DMI in our trilayers is orders of magnitude larger than that of known systems using heavy metals as a spacer except of recently reported −0.15 mJ/m2 in Co/Pt/Ru(t)/Pt/Co and varies between ≈ ±0.2 mJ/m2. In contrast to known multilayers Co/Ag/Co promotes in-plane chirality between magnetic layers. The strength of IL-DMI opens up new routes for design of three-dimensional chiral spin structures combining intra- and interlayer DMI and paves the way for enhancements of the DMI strength.

Spatial and Temporal Evolution of Coupling and Coordination between Scientific and Technological Innovation and Green Economy in Anhui Province

Spatial and Temporal Evolution of Coupling and Coordination between Scientific and Technological Innovation and Green Economy in Anhui Province

Analysis of the effect of the translational-rotational coupling on the pseudo-diffusion along the molecular axes of meta-cresol: A molecular dynamics analysis

We investigate the dynamical properties (translation and rotation) of the glass-forming liquid meta-cresol by molecular dynamics simulations. This system is investigated at 9 temperatures between 230 K and 400 K, encompassing the liquid and glassy states of meta-cresol. In order to get insight into the coupling between the translational and rotational motions, the centre of mass velocity autocorrelation function is calculated along the principal axes of meta-cresol. We show that the time behaviour of the velocity and angular velocity is connected to the change in the local structure occurring upon the glass transition. Indeed, the long-time negative region in the velocity autocorrelations is associated with a caging effect while the occurrence of a short time negative region in these functions is considered as a signature of hydrogen bonding interactions. By studying, the centre of mass velocity of meta-cresol in the molecular frame, the translation and rotation coupling was directly evidenced. The time evolution of the translational-rotational coupling is evaluated from the difference ΔαRTC(t) between the velocity autocorrelation function calculated with respect to the molecular frame (where α stands for the three axes of the local cartesian frame fixed to the individual molecule, x, y, and z) of the meta-cresol molecule and that of the same function calculated in the frame of the hypothesis that there is no statistical correlation between the translational and rotational motions. The positive regions of ΔαRTC(t) indicate an occurrence of a cooperative effect, which means that the each of the two motions is realized in the favour of the other. Conversely, negative regions indicate that the rotation and translation motions are anti-cooperative. Our results show that a strong coupling between translation and rotation occurs along the × axis that is perpendicular to the ring of meta-cresol molecule, and also along which the hydrogen bond is established.

An ontology-based data-model coupling approach for digital twin

Digital twin (DT), which strives to achieve physical-virtual fusion, has made great strides with its widely applications in various fields. Based on data interaction, DT reflects the real-time conditions of physical scenarios in a safe-virtual space and further generates dynamic decisions. However, there are still some vital challenges to be addressed during the implementation of DT. A crucial challenge lies in bridging the gap between the physical and virtual spaces, in order to realize physical-virtual consistency. To address the challenge, an ontology-based data-model coupling method is firstly proposed in this paper, consisting of three primary procedures, relation establishment, data-model coupling and relation evolution. Subsequently, detailed implementations of the above procedures are illustrated. Finally, experiments are carried out to prove the feasibility and practicability of the proposed method.

Numerical study on the fluid dynamics for tandem water entries of two cylinders

A three-dimensional numerical model is established to simulate the tandem water entry at different time intervals between two cylinders. The evolution of cavity, pressure field, velocity field and multi-scale vortex structures during water entry are studied. The motion characteristics of the tandem cylinders are analyzed to investigate the coupling effect of the flow field. Numerical results show that the water entry of the first cylinder significantly changes the flow field distribution, resulting in the complex flow field coupling evolution and the decrease of impact load on the trailing cylinder. For a time interval of 1.8 ms or 2.8 ms, the trailing cylinder enters the first cavity and then accelerates to catch up with the first cylinder under the effect of the pressure difference until collision. As the time interval increases to 4.8 ms, the trailing cylinder experiences a lower drag and forms a conical cavity, decelerating with a small deflection tendency. Moreover, cavity evolution is accompanied by the formation and dissipation of vortices and the vortex structures of tandem cylinders affect each other in different degrees.

Modelling the Coupling Relationship between Urban Road Spatial Structure and Traffic Flow

In order to promote the sustainable development of urban traffic systems, improve the accuracy of traffic system analysis in the urban planning stage and reduce the possibility of traffic congestion in the operation stage of road networks, the coupling relationship and evolution mechanism between urban road spatial structure and traffic flow were studied, and a model of the relationship between the metrics was established in this study based on real road network and traffic flow data. First, the road spatial structure model of the study area was established from the perspective of road space, and the spatial syntax method was applied to verify the rationality of the spatial structure of the road network. Secondly, the initial OD matrix was determined by OD backpropagation based on the measured traffic flow data. Thirdly, the coupling rule between the spatial structure and the traffic flow of the road network was explored by loading the increment in the OD matrix to the initial OD matrix step by step based on a simulation experiment. Finally, the relationship between the degree of integration of the spatial syntactic feature parameter and the saturation of the traffic flow feature parameter was modelled on the basis of experimental results and verified by an example. This research shows that the spatial structure of urban roads has a significant impact on the characterisation of the traffic flow distribution of road networks, and a strong correlation can be found between the integration degree and saturation degree. An optimal fit, which can be used as a reference for the design of road spatial structure, was explored in this research.

Optimization of laser irradiation process parameters for 40Cr steel based on back propagation neural network and genetic algorithm

40Cr is a significant material in the manufacturing of gears. However, this process is plagued by uneven distribution of quenching layers and excessive residual stress, leading to a decline in the precision of the workpiece, deformation, and cracking. Relying solely on the trial-and-error method in experiments is inadequate for effectively revealing the evolution mechanism of the laser quenching process. This approach is detrimental to improving research and development efficiency. In this study, a multi-field coupled numerical model for the multi-track overlapping laser quenching of the 40Cr gear steel is established. This model quantitatively reveals the coupling evolution laws of the temperature field, stress field, and phase transformation field during the laser quenching. The focus is on calculating the size of the tempering zone under different overlapping rates and conducting correlation analysis between parameters. Based on the artificial neural networks and genetic algorithms, the width and depth of the tempering zone are selected as target values for parameter optimization. The aim is to find the nonlinear relationship between the laser power, spot diameter, scanning speed, laser overlapping rate, and the size of the tempering zone, which can accurately predict the size of the tempering zone. The material microstructure of 40Cr gear steel was characterized by the scanning electron microscope, microhardness tester and friction and wear tester. The results show that the training error and testing error of the output parameters in genetic algorithm optimized back propagation network can accurately predict the size of the tempering zone. It is found that the higher the lap rate, the more uniform the hardness of the phase transformation hardening layer surface, and the tempering softening zone becomes larger. The parts surface is easy to produce defects, which can provide a theoretical basis for optimizing the laser quenching process parameters.

Evolution and Prognostic Impact of Right Ventricular–Pulmonary Artery Coupling After Transcatheter Aortic Valve Replacement

BackgroundThere is limited evidence regarding the association between right ventricular-to-pulmonary artery (RV-PA) coupling and outcomes after transcatheter aortic valve replacement (TAVR). ObjectivesThis study aimed to explore the evolution of RV-PA coupling in patients with severe aortic stenosis undergoing TAVR and its prognostic impact. MethodsA total of 900 patients who underwent TAVR in 2 tertiary centers and with echocardiographic analysis performed within 3 months before and after the procedure were included. RV-PA coupling was measured as the ratio of tricuspid annular plane systolic excursion (TAPSE) to pulmonary artery systolic pressure (PASP). RV-PA uncoupling was defined by TAPSE/PASP <0.55, whereas a TAPSE/PASP <0.32 identified a severe uncoupling. The primary endpoint was all-cause mortality. ResultsA total of 520 patients (58%) showed RV-PA uncoupling before TAVR, whereas post-TAVR RV-PA uncoupling was observed in 407 patients (45%). During a median follow-up of 40 months, 250 deaths (28%) occurred. Post-TAVR RV-PA uncoupling was independently associated with an increased risk of mortality (adjusted HR: 1.474; 95% CI: 1.115-1.948; P = 0.006), whereas pre-TAVR uncoupling did not. Among patients with post-TAVR RV-PA uncoupling, the presence of severe uncoupling identified a subgroup with the worst survival (P = 0.008). Patients with RV-PA coupling recovery after TAVR showed similar outcomes as compared with patients with normal coupling. Conversely, the presence of either persistent or new-onset RV-PA uncoupling following TAVR was associated with an increased mortality risk. ConclusionsPost-TAVR RV-PA uncoupling is an independent predictor of long-term mortality, irrespective of coupling before intervention. Assessment of TAPSE/PASP response after TAVR may be helpful to improve risk stratification.

Evolution and prognostic impact of right ventricular to pulmonary artery coupling after transcatheter aortic valve implantation

Abstract Funding Acknowledgements Type of funding sources: None. Background there is limited evidence regarding the association between right ventricular-to-pulmonary artery (RV-PA) coupling and outcomes after transcatheter aortic valve implantation (TAVI). Particularly, the prognostic value of post-TAVI RV-PA coupling has not been investigated so far. Purpose We aimed to explore the evolution of RV-PA coupling in patients with severe aortic stenosis (AS) undergoing TAVI and its prognostic impact. Methods A total of 900 patients who underwent TAVI in two tertiary centers and with echocardiographic analysis performed within 3 months before and after the procedure were included. RV-PA coupling was measured as the ratio of tricuspid annular plane systolic excursion (TAPSE) to pulmonary artery systolic pressure (PASP). On the basis of current evidence, RV-PA uncoupling was defined by TAPSE/PASP&amp;lt;0.55, whereas a TAPSE//PAS&amp;lt;0.32 identified a severe uncoupling. Primary endpoint was all-cause mortality. Results A total of 520 (58%) patients showed RV-PA uncoupling before TAVI, whereas post-TAVI RV-PA uncoupling was observed in 407 (45%) patients. During a median follow-up of 40 months, 250 (28%) deaths occurred. In multivariable Cox regression analyses adjusted for significant clinical, procedural and echocardiographic variables, post-TAVI RV-PA uncoupling was independently associated with an increased risk of mortality (adjusted hazard ratio [HR]:1.450, 95% Confidence interval [CI]:1.094–1.921, p = 0.010), while pre-TAVI uncoupling did not. Among patients with post-TAVI RV-PA uncoupling, the presence of severe uncoupling identified a subgroup with the worst survival (adjusted HR: 1.907, 95%CI:1.160–2.815, p = 0.009) (Figure 1). Notably, post-TAVI RV-PA uncoupling provided better risk stratification for all-cause mortality, than its components considered separately (i.e. TAPSE and PASP). Patients with RV-PA coupling recovery after TAVI (n=173, 33% of patients with pre-TAVI uncoupling) showed similar outcomes as compared to patients with normal coupling. Conversely, the presence of either persistent or new-onset RV-PA uncoupling following TAVI (n=347 and n=67) was associated with an increased risk of death (adjusted HR:1.422, 95%CI:1.025–1.974, p = 0.035 and adjusted HR: 2.247, 95%CI:1.403–3.599, p = 0.001, respectively) (Figure 2). Conclusions Post-TAVI RV-PA uncoupling is an independent predictor of long-term mortality, irrespective from coupling before intervention. Assessment of TAPSE/PASP response after TAVI may be helpful to improve patients’ risk stratification.

Stretch Evolution of Electronic Coupling of the Thiophenyl Anchoring Group with Gold in Mechanically Controllable Break Junctions.

The current-voltage characteristics of a single-molecule junction are determined by the electronic coupling Γ between the electronic states of the electrodes and the dominant transport channel(s) of the molecule. Γ is profoundly affected by the choice of the anchoring groups and their binding positions on the tip facets and the tip-tip separation. In this work, mechanically controllable break junction experiments on the N,N'-bis(5-ethynylbenzenethiol-salicylidene)ethylenediamine are presented, in particular, the stretch evolution of Γ with increasing tip-tip separation. The stretch evolution of Γ is characterized by recurring local maxima and can be related to the deformation of the molecule and sliding of the anchoring groups above the tip facets and along the tip edges. A dynamic simulation approach is implemented to model the stretch evolution of Γ, which captures the experimentally observed features remarkably well and establishes a link to the microscopic structure of the single-molecule junction.

Ultrathin ZnIn2S4 Nanosheets-Supported Metallic Ni3FeN for Photocatalytic Coupled Selective Alcohol Oxidation and H2 Evolution

Photocatalytic anaerobic organic oxidation coupled with H2 evolution represents an advanced solar energy utilization strategy for the coproduction of clean fuel and fine chemicals. To achieve a high conversion efficiency, the smart design of efficient catalysts by the right combination of semiconductor light harvesters and cocatalyst is highly required. Herein, we report a composite photocatalyst composed of noble metal-free transition metal nitride Ni3FeN decorated on 2D ultrathin ZnIn2S4 (ZIS) nanosheets for selective oxidation of aromatic alcohols to aldehydes pairing with H2 production. In the composite, ultrathin ZIS serves as a light harvester that greatly shortens the diffusion length of photogenerated charges, while the metallic nitride Ni3FeN acts as an advanced cocatalyst which not only captures the photoelectrons generated from the ultrathin ZIS to promote the charge separation, but also provides active sites to lower the overpotential and accelerate the H2 reduction. The best photocatalytic performance is found on ZIS/1.5% M-Ni3FeN, which shows a H2 generation rate of 2427.9 µmol g−1 h−1 and a benzaldehyde (BAD) production rate of 2460 µmol g−1 h−1, about 7.8-fold as high as that of bare ZIS. This work is anticipated to endorse the exploration of transition metal nitrides as high-performance cocatalysts to promote the coupled photocatalytic organic transformation and H2 production.

The scaling of primordial gauge fields

The large-scale magnetic fields arising from the quantum mechanical fluctuations of the hypercharge are investigated when the evolution of the gauge coupling is combined with a sufficiently long inflationary stage. In this framework the travelling waves associated with the quantum mechanical initial conditions turn asymptotically into standing waves which are the gauge analog of the Sakharov oscillations. Even if the rate of dilution of the hypermagnetic and hyperelectric fields seems to be superficially smaller than expected from the covariant conservation of the energy-momentum tensor, the standard evolution for wavelengths larger than the Hubble radius fully accounts for this anomalous scaling which is anyway unable to increase the amplitude of the magnetic power spectra after symmetry breaking. An effective amplification of the gauge power spectra may instead occur when the post-inflationary expansion rate is slower than radiation. We stress that the modulations of the gauge power spectra freeze as soon as the relevant wavelengths reenter the Hubble radius and not at the end of inflation. After the Mpc scale crosses the comoving Hubble radius the scaling of the magnetic power spectrum follows from the dominance of the conductivity. From these two observations the late-time values of the magnetic power spectra are accurately computed in the case of a nearly scale-invariant slope and contrasted with the situation where the phases of Sakharov oscillations are not evaluated at horizon crossing but at the end of inflation, i.e. when all the wavelengths relevant for magnetogenesis are still larger than the comoving horizon.