Direct Coupling Research Articles

Comparative Analysis of Hydrogen Production and Economic Feasibility: Direct versus Indirect Coupling of Photovoltaic Systems with Electrolyzers

Hydrogen production using photovoltaics (PV) is essential for decarbonizing many sectors of the economy. The integration of PV and hydrogen electrolyzers is actively debated, with focus on direct versus indirect configurations and the option of storage. Direct configuration connects PV directly to the electrolyzer, offering simplicity and reduced installation costs but depends on the weather for efficient power transfer. Indirect configuration adds a power stage, increasing complexity and losses, but enabling maximum power tracking. Adding batteries allows storage of excess PV energy, extending hydrogen production. This study optimizes a PV generator to maximize annual hydrogen production in the direct configuration, then uses the same PV array for indirect configurations with and without batteries for a fair comparison. Results show that the indirect configuration with a battery yields 78% more hydrogen annually than without a battery and 109% more than the direct configuration. The indirect configuration with a battery uses 86.9% of PV energy for hydrogen production, yielding the highest profit at 2.53 € ⋅ W−1 (euros per watt‐peak of PV), compared to the direct and indirect configurations without a battery, which use 41.9% and 44.6% of PV energy and generate 1.49 and 1.83 € ⋅ W−1, respectively.

Iodide Ion-Promoted Highly Regioselective Triazolization of Aldehydes via Desulfonation-Associated Direct Radical Coupling

Iodide Ion-Promoted Highly Regioselective Triazolization of Aldehydes via Desulfonation-Associated Direct Radical Coupling

Enantioselective Electrocatalysis for Cross‐Dehydrogenative Heteroarylation with Indoles, Pyrroles, and Furans

AbstractOxidative cross‐dehydrogenative C−H/C−H functionalizations represent an exemplary approach for synthesizing carbonyl compounds via α‐heteroarylation. Here we present the development of a direct anodic oxidative coupling process between 2‐acylimidazoles and divergent heterocyclic systems including indole, pyrrole, and furan, facilitated by ferrocene‐assisted asymmetric nickel electrocatalysis with high levels of enantioselectivity. Mechanistic investigations indicate that the reaction initially involves the formation of a chiral Ni‐bound α‐carbonyl radical, which is then captured by the heteroarene radical cation via intermolecular stereoselective radical/radical cation coupling. The mild, scalable, and robust reaction conditions allow for a broad substrate scope and excellent functional group tolerance, enabling access to a wide range of chiral hetero‐compounds. The consequential α‐heteroaromatic carbonyl products can potentially be transformed into a plethora of synthetically valuable frameworks, as exemplified by their application in the asymmetric total synthesis of (−)‐COX‐2 inhibitor, (+)‐acremoauxin A, and (+)‐pemedolac.

Cross Peaks on Two-Dimensional Optical Spectra Arising from Quantum Cross-Correlation Functions.

Cross peaks on 2D optical spectra are indicative of interactions between molecular excitonic states. Currently, the two conventional assignments of cross peaks are direct coupling and population transfer between excitonic states. Here, we show that there is another possible source of cross peaks. We theoretically demonstrate that for a model comprising two nondirectly interacting excitons or two-level systems (TLSs), cross peaks can arise if there is a complex-valued or quantum frequency-gap cross-correlation function between the two TLSs. Considering only real-valued or classical cross-correlation functions will result in no cross peaks. We derive and validate the mathematical expressions describing such cross peaks. We then simulate the 2D electronic spectra of an example model system comprising nondirectly interacting TLSs whose quantum cross-correlation functions arise from coupling to a common overdamped Brownian oscillator mode. We show that there are clear observational differences between such quantum correlation cross peaks with conventional direct coupling and population transfer cross peaks.

Steering Nonlinear Chiral Valley Photons Through Optical Orbit–Orbit Coupling

AbstractTwo‐dimensional transition metal dichalcogenides feature a direct tunable bandgap and robust spin‐valley coupling, offering an additional valley degree of freedom for information carriers. While optical spin‐orbit coupling has traditionally facilitated valley manipulation, on‐chip control of nonlinear valley photons remains elusive. Here, the directional coupling of nonlinear chiral valley photons through optical orbit‐orbit coupling in monolayer tungsten disulfide at room temperature is demonstrated. The chirality of nonlinear valley photons is governed by the spin angular momentum of the pump light, adhering to nonlinear selection rules. Importantly, the coupling direction is controlled by the orbital angular momentum of the pump light, facilitated by the orbital momentum flux. This approach not only provides a novel method for manipulating the valley degree of freedom but also enhances the flexibility of directing valley photon emission and on‐chip routing. These developments hold promising prospects for advanced valley optoelectronic devices.

Observing vibronic coupling in a strongly hydrogen bonded system with coherent multidimensional vibrational-electronic spectroscopy.

The coupled structural and electronic parameters of intramolecular hydrogen bonding play an important role in ultrafast chemical reactions, such as proton transfer processes. We perform one- and two-dimensional vibrational-electronic (1D and 2D VE) spectroscopy experiments to understand the couplings between vibrational and electronic coordinates in 10-Hydroxybenzo[h]quinoline, an ultrafast proton transfer system. The experiments reveal that the OH stretch (νOH) is strongly coupled to the electronic excitation, and Fourier analysis of the 1D data shows coherent oscillations from the low frequency backbone vibrational modes coupled to the νOH mode, resulting in an electronically detected vibronic signal. In-plane low-frequency vibrations at 242 and 386 cm-1 change the hydrogen bond distance and modulate the observed electronic signal in the polarization-selective 1D VE experiment through orientation-dependent coupling with the νOH mode. Resolution of the excitation frequency axis with 2D VE experiments reveals that excitation frequency, detection frequency, and experimental delay affect the frequency and strength of the vibronic transitions observed. Our results demonstrate evidence of direct coupling of the high frequency νOH mode with the S1 ← S0 electronic transition in 10-Hydroxybenzo[h]quinoline (HBQ), and orientation-dependent couplings of the low-frequency 242 and 386 cm-1 modes to the νOH mode and the electronic transition. This demonstration of multidimensional VE spectroscopy on HBQ reveals the potential of using 1D and 2D VE spectroscopy to develop a quantitative understanding of the role of vibronic coupling in hydrogen bonding and ultrafast proton transfer for complex systems.

High coupling efficiency with large axial direction coupling adjustment range in water-jet guided laser

In the traditional water-jet guided laser (WJGL) processing system, convex lens is used to focus Gaussian laser beam, where the waist and divergence angle are constrained. The focal depth is small, and there are problems such as divergence angle and aberration, which results in the difficult coupling adjustment because the adjustment range of laser coupling to water-jet fiber is limited to the Rayleigh range. In this study, non-diffraction laser (NDL) is generated by an axicon, which has the characteristics of small central spot and large non-diffraction range (NDR). The axial random coupling is realized in the NDR, and the problem of axial coupling between the focused laser and the water-jet generated by nozzle micro-hole is solved. Besides, this paper presents a novel technique to generate NDL by the combination of concave axicon (CCA) and convex axicon (CVA), which solves the small cone angle of the single CVA and the non-modulation defect of the corresponding optical and mechanical structure, and extends the starting point of the NDR to improve the coupling utilization rate of the NDR and the flexibility of the system. The focusing and coupling transmission characteristics of convex lens and axicons mode in WJGL are compared and analyzed. The generated NDL in the NDR at the axial reference coordinate point position of 50 mm and 70 mm is successfully coupled into the water-jet fiber. After the coupling transmission of 20 mm, the coupling efficiency, the morphology of the transmitted spot and the peak power density were basically the same, and the coupling efficiency of the central spot was about 81 %. However, the output spot peak power density and coupling efficiency decrease sharply when the axial coupling deviation exceeds 5 mm adopting convex lens. In contrast, the NDL can achieve a random coupling with high axial coupling tolerance in NDR. The research provides a solution for efficient adjustment and transmission of laser coupling into water-jet in highly stable WJGL.

General Analytical Model for Electromagnetic-Thermal Bi- Directional Coupling of IPM Motors in Electric Vehicles Considering Different Rotor Structures

General Analytical Model for Electromagnetic-Thermal Bi- Directional Coupling of IPM Motors in Electric Vehicles Considering Different Rotor Structures

Preliminary Implementation of High-Resolution Multi-Scale coupling calculations for the entire pressure vessel based on OpenFOAM

Significant coupling effects exist among system components in nuclear pressure vessel. Due to the complex geometric structures, the nuclear industry primarily relies on system codes or sub-channel methods for core safety analysis. However, these methods suffer from low model accuracy and insufficient coupling capabilities. Additionally, the differences in model scales impede direct coupling analysis with the CFD calculations of the plenum system. To address these issues, this paper proposes a multi −scale coupling calculation method for the entire pressure vessel: For the plenum system, detailed CFD modeling is employed, while the core calculations are conducted using CorTAF, a high-resolution core Multiphysics-coupling analysis method developed by our team. A cross-resolution coupling model is utilized to integrate the two, achieving cross-resolution coupling simulations for the entire pressure vessel, encompassing both the plenum and core system. The above method was applied to the coupling calculations of a typical pressurized water reactor’s lower plenum and core, revealing detailed thermal–hydraulic phenomena under precise core flow inlet distribution conditions. The lateral flow at the core inlet exceeds 1 m/s, with the maximum and minimum fluid velocities in the subchannels deviating by up to 70 % from the average velocity of 2.42 m/s. The flow distribution only begins to stabilize after a height of 1.2 m in the core. The paper also includes inlet asymmetric flow reduction calculations. Overall, the method enables multi-scale and multi-physics coupling calculations, which provide significant reference value for improving the accuracy of current core safety analyses.

Two-Fold Oxidative Coupling of Furan with Indole Provides Modular Access to a New Class of Tetra-(Hetero)Arylated Furans with Up to Four Different Substituents.

Highly arylated propeller-shaped heteroarenes constitute an intriguing class of molecular scaffolds for material science applications. Among these, tetraarylated furans demonstrate differentiated properties as compared to other similar heterocyclic cores. The synthetic complexity to access tetraarylated furans increases significantly with increasing number of different peripheral aryl groups. There are only a very limited number of methodologies available to access furans with four different (hetero)aryl substituents. Notably, none of these involve direct oxidative coupling on the furan core as the method of choice. Herein, we report the first methodology based on a sequential two-fold oxidative C-C coupling of furans with indoles to access bis(indolyl)furans (BIFs) - a new class of 'extremely congested' tetra-(hetero)arylated furans with up to four different substituents. The reaction is mediated by inexpensive, earth-abundant FeCl3⋅6H2O and displays high efficiency, wide substrate scope, modularity and aqueous compatibility. Moreover, we also present the first validation of the distinct aggregation-caused quenching (ACQ) property of the tetraarylated furans beyond only phenyls as peripheral groups and disclose new mechanistic underpinnings for the same.

A Direct Visible‐Light Mediated Coupling Of Azaarenes with Diversely Functionalized Alkyl Carbons via Organophotocatalytic Sp3C−H Bond Activation

AbstractSubstituted azaarenes are one of the most ubiquitous moieties in natural products and drug molecules. An efficient organophotocatalytic method for direct coupling of diverse cyclic and acyclic alkyl carbons of alcohols, ethers, alkyl halides and alkanes with different azaaryl systems has been developed. It uses low loading of easily synthesizable efficient acridinium based photocatalyst and blue LED to generate highly reactive radicals on saturated hydrocarbons through sequential single electron transfer (SET) and hydrogen atom transfer (HAT) process. These in situ generated nucleophilic carbon radicals then undergo instantaneous regio‐selective coupling with azaarenes through Minisci type coupling to generate an array of important pharmacophores through sp2C−sp3C bond formation. With inexpensive organophotocatalysts, higher yield and wide substrate scope, this method provides a greener, efficient and versatile alternative to the previously reported syntheses.

A Strongly Coupled Metal/Hydroxide Heterostructure Cascades Carbon Dioxide and Nitrate Reduction Reactions toward Efficient Urea Electrosynthesis.

The direct coupling of nitrate ions and carbon dioxide for urea synthesis presents an appealing alternative to the Bosch-Meiser process in industry. The simultaneous activation of carbon dioxide and nitrate, however, as well as efficient C-N coupling on single active site, poses significant challenges. Here, we propose a novel metal/hydroxide heterostructure strategy based on synthesizing an Ag-CuNi(OH)2 composite to cascade carbon dioxide and nitrate reduction reactions for urea electrosynthesis. The strongly coupled metal/hydroxide heterostructure interface integrates two distinct sites for carbon dioxide and nitrate activation, and facilitates the coupling of *CO (on silver, where * denotes an active site) and *NH2 (on hydroxide) for urea formation. Moreover, the strongly coupled interface optimizes the water splitting process and facilitates the supply of active hydrogen atoms, thereby expediting the deoxyreduction processes essential for urea formation. Consequently, our Ag-CuNi(OH)2 composite delivers a high urea yield rate of 25.6 mmol gcat. -1 h-1 and high urea Faradaic efficiency of 46.1 %, as well as excellent cycling stability. This work provides new insights into the design of dual-site catalysts for C-N coupling, considering their role on the interface.

Dual Photoredox and Titanium Catalyzed Regioselective Allenylation of Aldehydes via Reductive Radical‐Polar Crossover

Comprehensive SummaryThe direct reductive coupling of carbonyl compounds with propargyl halides is a powerful and reliable tool in the synthesis of α‐allenols. However, stoichiometric metal reductants, harsh reaction conditions and a variety of additional additives are required in the traditional strategies. Additionally, the reactivity and regioselectivity control remains an elusive challenge. Herein, we developed the Ti‐catalyzed regioselective reductive coupling of readily available aldehydes and racemic propargyl bromides to rapidly access a wide range of α‐allenols. This method proceed efficiently in a reductive radical‐polar crossover manner featuring mild conditions, excellent regioselectivity control, broad substrate scope, and eco‐friendliness. Preliminary mechanistic studies support the radical‐involved catalytic cycle. And the DFT calculations demonstrate that the regioselectivity is determined by the Zimmerman‐Traxler‐type transition states.

Directional Coupling to a λ/5000 Nanowaveguide.

Silicon-based microdevices are considered promising candidates for consolidating several terahertz technologies into a common and practical platform. The practicality stems from the relatively low loss, device compactness, ease of fabrication, and wide range of available passive and active functionalities. Nevertheless, typical device footprints are limited by diffraction to several hundreds of micrometers, which hinders emerging nanoscale applications at terahertz frequencies. While metallic gap modes provide nanoscale terahertz confinement, efficiently coupling to them is difficult. Here, we present and experimentally demonstrate a strategy for efficiently interfacing subterahertz radiation (λ = 1 mm) to a waveguide formed by a nanogap, etched in a gold film, that is 200 nm (λ/5000) wide and up to 4.5 mm long. The design principle relies on phase matching dielectric and nanogap waveguide modes, resulting in efficient directional coupling between them when they are placed side-by-side. Broadband far-field terahertz transmission experiments through the dielectric waveguide reveal a transmission dip near the designed wavelength due to resonant coupling. Near-field measurements on the surface of the gold layer confirm that such a dip is accompanied by a transfer of power to the nanogap, with an estimated coupling efficiency of ∼10%. Our approach efficiently interfaces millimeter waves with nanoscale waveguides in a tailored and controllable manner, with important implications for on-chip nanospectroscopy, telecommunications, and quantum technologies.

Enantioselective Electrocatalysis for the Cross-Dehydrogenative Heteroarylation of Indoles, Pyrroles, and Furans.

Oxidative cross-dehydrogenative C-H/C-H functionalizations represent an exemplary approach for synthesizing carbonyl compounds via α-heteroarylation. Here we present the development of a direct anodic oxidative coupling process between 2-acylimidazoles and divergent heterocyclic systems including indole, pyrrole, and furan, facilitated by ferrocene-assisted asymmetric nickel electrocatalysis with high levels of enantioselectivity. Mechanistic investigations indicate that the reaction initially involves the formation of a chiral Ni-bound α-carbonyl radical, which is then captured by the heteroarene radical cation via intermolecular stereoselective radical/radical cation coupling. The mild, scalable, and robust reaction conditions allow for a broad substrate scope and excellent functional group tolerance, enabling access to a wide range of chiral hetero-compounds. The consequential α-heteroaromatic carbonyl products can potentially be transformed into a plethora of synthetically valuable frameworks, as exemplified by their application in the asymmetric total synthesis of (-)-COX-2 inhibitor, (+)-acremoauxin A, and (+)-pemedolac.

Verification of direct coupling code system using FRENDY version 2 and GENESIS for light water reactor lattices

ABSTRACT This study newly established a direct coupling code system consisting of the nuclear data processing code FRENDY version 2, and the three-dimensional heterogeneous transport code GENESIS (FRENDY-V2/GENESIS) for easy implementation of the random-sampling-based uncertainty quantification considering the implicit effect due to nuclear cross-section (XS) perturbations. The multi-group macroscopic XSs prepared for GENESIS were generated by FRENDY version 2, where the Dancoff factor was calculated by the neutron current method. Then the background XSs were evaluated based on the Carlvik two-term rational approximation. The infinite multiplication factor (k-infinity) and the fission reaction rate distribution in UO2 and MOX lattice geometries were compared with MVP3 to verify the calculation accuracy of FRENDY-V2/GENESIS. The sensitivity analyses on the discretization conditions such as the ray tracing of the method of characteristics were also carried out. Through several comparisons between FRENDY-V2/GENESIS and MVP3, FRENDY-V2/GENESIS with the SHEM 361-group structure calculates the k-infinity within approximately 50 pcm and the fission reaction rate distribution within approximately 0.1% by the root mean square, respectively. Consequently, the applicability of FRENDY-V2/GENESIS was verified, and FRENDY-V2/GENESIS can be used to discuss the implicit effect due to multi-group XS perturbations.

Electroinduced Reductive and Dearomative Alkene-Aldehyde Coupling.

The direct coupling of alkene feedstocks with aldehydes represents an expedient approach to the generation of new and structurally diverse C(sp3)-hybridized alcohols that are primed for elaboration into privileged architectures. Despite their abundance, current disconnection strategies enabling the direct coupling of carbon-carbon π-bonds and aldehydes remain challenging because contemporary methods are often limited by substrate or functional group tolerance and compatibility in complex molecular environments. Here, we report a coupling between simple alkenes, heteroarenes and unactivated aliphatic aldehydes via an electrochemically induced reductive activation of C-C π-bonds. The cornerstone of this approach is the discovery of rapid alternating polarity (rAP) electrolysis to access and direct highly reactive radical anion intermediates derived from conjugated alkenes and heterocyclic compounds. Our developed catalyst-free protocol enables direct access to new and structurally diverse C(sp3)-hybridized alcohol products. This is achieved by the controlled reduction of conjugated alkenes and the C2-C3 π-bond in heteroarenes via an unprecedented reductive dearomative functionalization for heterocyclic compounds. Experimental mechanistic studies demonstrate a kinetically biased single-electron reduction of C-C π-bonds over aldehydes. Application of rAP enables chemoselective generation of olefinic radical anion intermediates and avoids undesired saturative overreduction. Overall, this technology provides a versatile approach to the reductive coupling of olefin and heterocycle feedstocks with aliphatic aldehydes, offering straightforward access to diverse C(sp3)-rich oxygenated scaffolds.

Direct magnetoelectric coupling in Pr doping Bi6Ti3Fe2O18 relaxor ferroics

Single-phase multiferroics are fractional and rarely meet at room temperature. Direct magnetoelectric coupling in relaxor ferroic phase was observed in Bi6−xPrxTi3Fe2O18 (x = 0.0, 0.3, 0.6, 0.9, and 1.2) films, where the chemical disorder doping-induced effective internal pressure played a key role. It is analytically formulated from the phase-structure shift, ferroelectric domain, and origin of the magnetic order. The strip magnetic domains are broken into a dotted domain structure following a quantitatively increase in lattice stress. A Monte Carlo simulation including stress energy items is used to unveil the hitherto unexplored coupling mechanism by tuning the symmetric exchange restriction of Fe3+–O–Fe3+. Moreover, the observation of coefficient 78.8 mV/cm·Oe at room temperature is intriguing for potential application.

The modified 6-chromanol SUL-238 protects against accelerated vascular aging in vascular smooth muscle Ercc1-deficient mice

Introduction: Vascular aging is marked by increased mitochondrial reactive oxygen species (ROS) production, which leads to decreased nitric oxide (NO)-mediated vasodilation. Loss of NO can be partially compensated by endothelium-derived hyperpolarization (EDH), which partly relies on increased mitochondrial Ca2+ release to maintain vascular dilation. Thus, intervention in mitochondria may target both NO and EDH signaling to alleviate aging-related vascular dysfunction. DNA damage by mitochondrial ROS is an important cause of organismal aging. Previous work showed that local vascular Ercc1 knockout dramatically accelerates vascular aging. The aim of the study was to investigate the effect of chronic treatment with the modified 6-chromanol, SUL-238, an inhibitor of mitochondrial reverse electron flux and ROS, in a mouse model of accelerated vascular smooth muscle aging induced by DNA repair endonuclease Ercc1 knockout (SMC-KO). Aim: The aim of the study was to investigate the effect of chronic treatment with the modified 6-chromanol, SUL-238, an inhibitor of mitochondrial reverse electron flux and ROS, in a mouse model of accelerated vascular smooth muscle aging induced by DNA repair endonuclease Ercc1 knockout (SMC-KO). Methods: SMC-KO mice and healthy wild-type littermates received SUL-238 (90 mg/kg/day) in drinking water from 12 to 22 weeks of age. At the age of 21 weeks, arterial stiffness was measured in vivo with echography and they were euthanized at the age of 22 weeks. Ex vivo vascular function was assessed in wire myography setups and mitochondrial function of the thoracic aorta was assessed using a seahorse assay. Results: SMC-KO mice showed reduced EDH-mediated vasodilation, elevated arterial stiffness, and increased elastin breaks at 22 weeks of age compared to their wild-type littermates. SUL-238 improved EDH, thus restoring aortic and mesenteric relaxation in SMC-KO mice. Furthermore, the number of elastin breaks was reduced and arterial stiffness normalized after treating SMC-KO mice with SUL-238. Mitochondrial respiration measured in the aorta was not different between the groups. Conclusion: Chronic treatment with SUL-238 alleviates features of vascular aging, including decreased vasodilation and increased arterial stiffness. SUL-238 seems to have a more general effect on aging rather than involving a direct coupling between mitochondrial function and vascular signaling. SUL-238 is the first small-molecule drug reported to increase EDH after chronic treatment.

Photoinduced Copper-Catalyzed Cross-Coupling of Acylsilanes with Heteroarenes via Bimetallic Relay.

The transition metal-catalyzed direct coupling reactions involving electron-rich Fischer carbene species are largely underdeveloped and remain a big challenge. Here, a direct coupling reaction of azoles and azine N-oxides is reported with Fischer copper carbene species bearing an α-siloxy group i, which can be in situ generated from acylsilanes catalytically under photoirradiation and redox-neutral conditions. This coupling reaction between electron-rich α-siloxy Fischer Cu-carbene species with hard carbanion nucleophiles may undergo a bimetallic relay process, which is confirmed by the kinetic analysis and in situ NMR analysis. This reaction features mild conditions and remarkable heterocycle compatibility. Notably, this protocol tolerates a series of azole or azine N-oxide derivatives, including benzoxazole, benzothiazole, benzoimidazole, benzoisoxazole, oxazole, oxadiazole, triazolo[4,3-a]pyridine, purine, caffeine, pyridine N-oxide, quinoline N-oxide, pyrazine N-oxide, pyridazine N-oxide, etc. The synthetic value of this approach is demonstrated by the efficient synthesis of a histamine h4 receptor ligand and a marketed drug carbinoxamine.