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Highly entangled polyradical nanographene with coexisting strong correlation and topological frustration
The design of open-shell nanographenes is commonly limited to systems featuring a single magnetic origin. Now a strategy that combines topological frustration and electron–electron interactions has been developed to generate a butterfly-shaped nanographene that hosts four highly entangled π-spins and exhibits both ferromagnetic and anti-ferromagnetic coupling.
- Shaotang Song
- , Andrés Pinar Solé
- & Jiong Lu
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Article
| Open AccessUltrafast electronic relaxation pathways of the molecular photoswitch quadricyclane
Light-induced ultrafast switching between the molecular isomers norbornadiene and quadricyclane can reversibly store and release a substantial amount of chemical energy. Two competing pathways have now been identified by which electronically excited quadricyclane molecules relax to the electronic ground state, facilitating interconversion between the two isomers on different timescales.
- Kurtis D. Borne
- , Joseph C. Cooper
- & Daniel Rolles
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Article
| Open AccessTen-electron count rule for the binding of adsorbates on single-atom alloy catalysts
Single-atom alloys have emerged as highly active and selective catalysts that do not follow the traditional models of heterogeneous catalysis. Now it has been shown that the binding of adsorbates at their surface abides by a simple 10-electron count rule, which can identify promising catalysts for various applications.
- Julia Schumann
- , Michail Stamatakis
- & Romain Réocreux
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Azobenzene as a photoswitchable mechanophore
Light-induced azobenzene cis/trans isomerization has been extensively investigated, but the mechanical strength of its cis/trans structure is not well understood. Now it has been shown that cis azobenzene is mechanically less stable than the trans isomer due to its regiochemical structure, as revealed by single-molecule force spectroscopy.
- Yiran Li
- , Bin Xue
- & Yi Cao
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The role of aromaticity in the cyclization and polymerization of alkyne-substituted porphyrins on Au(111)
While aromaticity is a useful concept for assessing the reactivity of organic compounds, the connection between aromaticity and on-surface chemistry remains largely unexplored. Now, scanning probe experiments on cyclization reactions of porphyrins on Au(111) show that the peripheral carbon atoms outside of the aromatic 18-π electron pathway exhibit a higher reactivity.
- Nan Cao
- , Jonas Björk
- & Alexander Riss
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Article |
Direct observation of geometric-phase interference in dynamics around a conical intersection
Wavepacket dynamics around conical intersections are influenced by geometric phase, which can affect chemical reaction outcomes but has only been observed through indirect signatures. Now, by engineering a controllable conical intersection in a trapped-ion quantum simulator, the destructive wavepacket interference caused by a geometric phase has been observed.
- C. H. Valahu
- , V. C. Olaya-Agudelo
- & I. Kassal
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Quantum simulation of conical intersections using trapped ions
Geometric phase interference has been predicted to appear around conical intersections but has been experimentally illusive owing to competing effects in molecular systems. Now, this effect has been demonstrated in chains of trapped ions using state-of-the-art quantum simulation and read-out techniques.
- Jacob Whitlow
- , Zhubing Jia
- & Kenneth R. Brown
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C–H···π interactions disrupt electrostatic interactions between non-aqueous electrolytes to increase solubility
The energy density in redox flow batteries is currently limited by the solubility of dissolved redox species. Now it has been shown that intermolecular C–H···π interactions can disrupt electrostatic forces in these organic electrolytes to improve their solubility in non-aqueous solvents.
- Sharmila Samaroo
- , Charley Hengesbach
- & David P. Hickey
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Nucleation-mediated growth of chiral 3D organic–inorganic perovskite single crystals
While chiral hybrid organic–inorganic perovskites are promising materials for optoelectronic applications, the synthesis of three-dimensional single crystals has proven challenging. Now, a general strategy has been shown to synthesize chiral, three-dimensional perovskites by heterogeneous nucleation. The single-crystalline materials contain no chiral component; their chiroptical activity arises from supercells formed by chiral patterns of the A-site cations.
- Gaoyu Chen
- , Xiaoyu Liu
- & Xun Wang
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Research Briefing |
Towards quantum state-to-state understanding of ion–molecule collisions
Despite advances, understanding of the quantum state-to-state scattering dynamics between charged ions and neutral molecules at low collision energies remains limited. A high-resolution crossed-beam experiment with quantum state-selected ions prepared by laser photoionization and supporting trajectory surface-hopping calculations now provides insight into the quantum state-to-state collisional dynamics of a model charge-transfer reaction.
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Time-resolved imaging and analysis of the electron beam-induced formation of an open-cage metallo-azafullerene
Visualizing single-molecule reactions using electron microscopy can be difficult because of potential radiation damage from the electron beam. Now, however, it has been shown that a high-energy electron beam can be used to synthesize metallo-azafullerenes. Atomic-resolution, time-resolved transmission electron microscopy, with the help of computational calculations, is used to monitor the metal-encapsulation dynamics.
- Helen Hoelzel
- , Sol Lee
- & Dominik Lungerich
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Exciton annihilation in molecular aggregates suppressed through quantum interference
Exciton–exciton annihilation is conventionally assumed to be limited by diffusion. Now, using time-resolved photoluminescence microscopy to determine exciton diffusion constants and annihilation rates in two substituted perylene diimide aggregates, along with a microscopic model, it has been shown that annihilation can be suppressed through quantum interference of the spatial phase of delocalized excitons.
- Sarath Kumar
- , Ian S. Dunn
- & Libai Huang
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D3+ formation through photoionization of the molecular D2–D2 dimer
Trihydrogen cations are abundant in interstellar space and play a vital role in both star and organic molecule formation. Now it has been shown that D3+ cations can be directly produced through photoionization of molecular D2–D2 dimers.
- Yonghao Mi
- , Enliang Wang
- & André Staudte
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| Open AccessFibril formation and ordering of disordered FUS LC driven by hydrophobic interactions
Protein solutions can undergo liquid–liquid phase separation, by condensing into a dense phase that often resembles liquid droplets, which coexist with a dilute phase. Now it is shown that hydrophobic interactions, specifically at interfaces, can trigger a liquid–solid phase separation of a protein solution.
- Daria Maltseva
- , Sayantan Chatterjee
- & Mischa Bonn
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Real-time monitoring of reaction stereochemistry through single-molecule observations of chirality-induced spin selectivity
In situ chirality identification for single-molecule systems is not a straightforward task. Now, real-time chirality identification during a Michael addition reaction has been realized by continuous measurements of spin-polarized currents through a single-molecule junction, providing a promising method for studying symmetry-breaking reactions.
- Chen Yang
- , Yanwei Li
- & Xuefeng Guo
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News & Views |
Quantum spin chains go organic
An organic quantum magnet has been prepared in short chains of porphyrin derivatives through a combination of on-surface synthesis and atom manipulation using the tip of a scanning probe microscope.
- P. Jelínek
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Article |
Observation of resonances in the transition state region of the F + NH3 reaction using anion photoelectron spectroscopy
The transition state, a transient species where bond transformation occurs, fundamentally controls reaction dynamics. This important species can be probed through the photodetachment of an anionic precursor, as has now been shown in the F + NH3 reaction. A combination of theory and experiment reveals resonances that span the transition state.
- Mark C. Babin
- , Martin DeWitt
- & Daniel M. Neumark
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News & Views |
Rare radioisotopes at the ready
The study of rare isotopes, including many in the f-block, is a key step to advancing our fundamental understanding of these elements, but their scarcity poses challenges. Now, minute amounts of such materials have been isolated and characterized through complexation with polyoxometalate clusters.
- Kristina O. Kvashnina
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Quantum nanomagnets in on-surface metal-free porphyrin chains
Quantum nanomagnets, which display collective quantum behaviours, serve as important components in modern quantum technologies, but their fabrication has remained challenging. Quantum nanomagnets have now been constructed spin by spin in metal-free porphyrin chains, using on-surface synthesis and hydrogen manipulation using a scanning tunnelling microscope, and their collective quantum behaviours have been clearly resolved.
- Yan Zhao
- , Kaiyue Jiang
- & Shiyong Wang
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Different timescales during ultrafast stilbene isomerization in the gas and liquid phases revealed using time-resolved photoelectron spectroscopy
The influence that liquid environments have on the ultrafast excited-state dynamics of molecules is poorly understood. Using time-resolved photoelectron spectroscopy, the dynamics of the photoisomerization of stilbene in the gas and liquid phases have now been shown to be qualitatively similar—including the observation of vibrational coherences—but the timescales are significantly longer in the liquid phase.
- Chuncheng Wang
- , Max D. J. Waters
- & Hans Jakob Wörner
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News & Views |
Electric field maps in enzymes
How electric fields generated by enzyme active sites push and pull on substrates is important to their chemistry, but measuring them is difficult. Now, the electric field within an active site has been measured along two directions using a vibrational probe, revealing that the field effect in enzymes is different compared with that in bulk solvents.
- Anuj Pennathur
- & Jahan Dawlaty
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Article
| Open AccessTime-resolved terahertz–Raman spectroscopy reveals that cations and anions distinctly modify intermolecular interactions of water
Ions in salt solutions perturb the hydrogen bonding between the surrounding water molecules, altering the properties of water, but how ion polarity affects this is not fully understood. By monitoring the dissipation of terahertz energy in salt solutions, it has now been shown that intermolecular rotational-to-translational energy transfer is enhanced by highly charged cations and reduced by highly charged anions.
- Vasileios Balos
- , Naveen Kumar Kaliannan
- & Mohsen Sajadi
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Collisional excitation of HNC by He found to be stronger than for structural isomer HCN in experiments at the low temperatures of interstellar space
HCN and its isomer HNC are both observed in the interstellar medium and inelastic collisions with helium and other species strongly influence their derived abundances. Now it has been shown experimentally and theoretically that HNC is much more strongly excited than HCN in collisions with helium at the low temperatures of interstellar space.
- Brian M. Hays
- , Divita Gupta
- & Ian R. Sims
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Anisotropic dynamics of resonant scattering between a pair of cold aligned diatoms
The collision dynamics between a pair of aligned molecules in the presence of a scattering resonance provide the most sensitive probe of the long-range anisotropic forces important to chemistry. By simultaneously controlling the collision temperature and geometry between a pair of aligned D2 molecules, we unravel the anisotropic dynamics of a cold scattering process.
- Haowen Zhou
- , William E. Perreault
- & Richard N. Zare
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News & Views |
Molecular spins clock in
Electron spin relaxation, important in quantum information science, can be slowed down at clock transitions — which are insensitive to magnetic noise. It has now been shown that such transitions can be tuned, to high frequency, in rare-earth coordination complexes through control of s- and d-orbital mixing.
- Eric J. L. McInnes
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Fermi-phase-induced interference in the reaction between Cl and vibrationally excited CH3D
Influencing the products of a reaction through controlling the state of the reactants is a notable goal for chemists. It has now been shown that the reactivity of a pair of Fermi-coupled vibrational states of CH3D(v1-I and v1-II) with a chlorine atom depends not only on the constituent basis modes, but also on the relative phase of the two modes in their wave-functions.
- Huilin Pan
- & Kopin Liu
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Glory scattering in deeply inelastic molecular collisions
Molecular energy transfer is thought to follow a simple rule of thumb: high energy transfer requires hard collisions that result in backscattering. However, now it has been observed that an unexpected forward scattering occurs in NO–CO and NO–HD collisions even for high energy transfer. This is attributed to ‘hard-collision glory scattering’, a mechanism that appears to be ubiquitous in molecule–molecule collisions.
- Matthieu Besemer
- , Guoqiang Tang
- & Tijs Karman
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A 9.2-GHz clock transition in a Lu(II) molecular spin qubit arising from a 3,467-MHz hyperfine interaction
The s-orbital mixing into the spin-bearing d orbital associated with a molecular Lu(II) complex is shown to both reduce spin–orbit coupling and increase electron–nuclear hyperfine interactions, which substantially improves electron spin coherence. Combined with the potential to tune interactions through coordination chemistry, it makes this system attractive for quantum information applications.
- Krishnendu Kundu
- , Jessica R. K. White
- & Stephen Hill
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News & Views |
Hydration determines anion accumulation
Why do bulky anions solubilize macromolecules in water but precipitate out the corresponding monomers? The answer lies in the differences in local water structure. Polymers have now been shown to disrupt water structure more than their monomers, leading to an accumulation of anions near the polymers that increases their solubility.
- Aniket U. Thosar
- & Amish J. Patel
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Ultrafast energy transfer between π-stacked aromatic rings upon inner-valence ionization
Aromatic systems that interact non-covalently are important in many settings, such as base-pair stacking and DNA–drug interactions; however, their excited-state molecular dynamics are not fully understood. Now, intermolecular Coulombic decay in benzene dimers has been observed. The process is initiated by electron-impact ionization and proceeds through ultrafast energy transfer between the benzene molecules.
- Xueguang Ren
- , Jiaqi Zhou
- & Alexander Dorn
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Electron spin resonance of single iron phthalocyanine molecules and role of their non-localized spins in magnetic interactions
Electron spin resonance spectroscopy has traditionally been used to study large ensembles of spins, but its combination with scanning tunnelling microscopy recently enabled measurements on single adatoms. Now, individual iron phthalocyanine complexes adsorbed on a surface have been probed. Their spin distribution partially extends on the phthalocyanine, leading to a strong geometry-dependent exchange coupling interaction.
- Xue Zhang
- , Christoph Wolf
- & Taeyoung Choi
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News & Views |
Ionic glue
Charged nanoparticles can behave as large ions or as small colloids. Their interaction with multivalent ions has now been shown to reflect this dichotomy, providing new paths to large, self-assembled nanoparticle superstructures.
- Tobias Kraus
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News & Views |
Stabilized resonances are no less exciting
Excited anion states provide doorways for molecular electron capture. Now, two-dimensional photoelectron spectroscopy of cluster anions has been shown to be a powerful tool for revealing the role of the local environment in facilitating the process.
- C. Annie Hart
- & Richard Mabbs
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The effect of solvation on electron capture revealed using anion two-dimensional photoelectron spectroscopy
Although electron-driven chemistry is ubiquitous, how molecular electron capture is altered by solvent remains poorly understood. Now, using anion two-dimensional photoelectron spectroscopy, it is shown that the presence of water molecules can enhance electron capture and that considering the mechanism from the perspective of the anion offers further understanding.
- Aude Lietard
- , Golda Mensa-Bonsu
- & Jan R. R. Verlet
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News & Views |
Ultimate control in chemistry
Controlling reactions between molecules is a major fundamental goal in chemistry and doing so on the level of individual quantum states is very challenging. Now, control over the reactant state and full characterization of the product-state distribution of an ultracold bimolecular reaction has been demonstrated.
- Andreas Osterwalder
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Stereoelectronic effects in stabilizing protein–N-glycan interactions revealed by experiment and machine learning
Analysis of the thermodynamics of protein–N-glycan interactions perturbed by mutations has revealed an enthalpy–entropy compensation that depends on the electronics of the interacting side chains. Machine-learned and statistical models showed that protein–N-glycan interactions highly correlate with stereoelectronic effects, and that a major part of protein–N-glycan interactions can be explained using the energetic rules of frontier molecular orbital interactions.
- Maziar S. Ardejani
- , Louis Noodleman
- & Jeffery W. Kelly
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The photochemical reaction of phenol becomes ultrafast at the air–water interface
Reactions at the interface between water and other phases play important roles in various chemical settings. Now, ultrafast phase-sensitive interface-selective vibrational spectroscopy has revealed that the photoionization of phenol can occur four orders of magnitude faster at the water surface than in the bulk aqueous phase.
- Ryoji Kusaka
- , Satoshi Nihonyanagi
- & Tahei Tahara
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Nuclear spin conservation enables state-to-state control of ultracold molecular reactions
Energy scrambling in intermediate complexes—which form in many chemical reactions—presents a major challenge to state-to-state control. However, nuclear spin tends to remain unchanged throughout reactions and now, by manipulating the reactants’ nuclear spins using an external magnetic field, control over the product state distribution of a bimolecular reaction has been demonstrated.
- Ming-Guang Hu
- , Yu Liu
- & Kang-Kuen Ni
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Determining the nature of quantum resonances by probing elastic and reactive scattering in cold collisions
Low-temperature scattering leads to the formation of quantum resonances or quasi-bound states, which are observable as peaks in the measured collision cross-sections. Now it has been shown that two different formation mechanisms, quantum tunnelling and quantum reflection, can be distinguished by measuring and comparing elastic and inelastic scattering, which probe the spatial localization of the resonance wavefunctions.
- Prerna Paliwal
- , Nabanita Deb
- & Edvardas Narevicius
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State-to-state scattering of highly vibrationally excited NO at broadly tunable energies
Scattering experiments in which two beams nearly co-propagate allow broadly tunable collision energies and can enable cold collisions. Now, such experiments have been combined with the preparation of NO molecules using stimulated emission to generate highly vibrationally excited states for state-to-state scattering studies, testing the theoretical gold standard in a regime not found in nature.
- Chandika Amarasinghe
- , Hongwei Li
- & Arthur G. Suits
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Capturing intrinsic site-dependent spectral signatures and lifetimes of isolated OH oscillators in extended water networks
The broad infrared spectrum of water in the OH stretching region shows how significantly a water molecule is distorted when within a hydrogen-bonding network; it also raises the question of what the spectrum of a single OH oscillator would be. Now, the spectral signatures of isolated OH oscillators embedded in cold water cages have been measured using vibrational spectroscopy.
- Nan Yang
- , Chinh H. Duong
- & Mark A. Johnson
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Ultrafast X-ray scattering reveals vibrational coherence following Rydberg excitation
Quantum coherence and dephasing in molecular motions determine the behaviour of many chemical reactions and are the fundamental basis for the concept of coherent control. Now, ultrafast X-ray scattering combined with a detailed structural determination analysis precisely measures the coherent vibrational motions of a polyatomic organic molecule following photoexcitation.
- Brian Stankus
- , Haiwang Yong
- & Peter M. Weber
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News & Views |
Too slow to be activated
Light is often used to trigger reactions, energetically exciting the reactant(s) to kick them over the intrinsic reaction barrier. Now, however, the reaction between an excited atom and a charged molecule at very low temperatures has been shown not to adhere to this paradigm, instead undergoing a reaction blockading effect.
- Roland Wester
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Reaction blockading in a reaction between an excited atom and a charged molecule at low collision energy
The reaction between an excited atom and a charged molecule has now been studied at low temperature and a reaction blockading effect has been observed that differs significantly from what is expected from standard chemical capture theory.
- Prateek Puri
- , Michael Mills
- & Eric R. Hudson
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News & Views |
Unexpected intersystem crossing
Intersystem crossing plays a role in the mechanism of many reactive collisions between atomic species and organic molecules, and has been generally observed when the reactants are still approaching one another. Now, intersystem crossing has been observed to also occur after their initial interaction.
- Luis Bañares
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Intersystem crossing in the exit channel
Intersystem crossing (ISC) is a radiationless process that is important in many photophysical systems. It has now been observed to take place in the exit channel for the reaction of ground-state atomic oxygen with alkylamines.
- Hongwei Li
- , Alexander Kamasah
- & Arthur G. Suits
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News & Views |
Magnetic control of a reaction path
Magnetic or electric fields have long been used to align or orient atomic or molecular species in a molecular beam. Now, experiments in a merged beam apparatus show that an external magnetic field can be used to favour one particular reaction path.
- Astrid Bergeat
- & Christian Naulin
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Quantum-state-controlled channel branching in cold Ne(3P2)+Ar chemi-ionization
Steric effects in a fundamental energy-transfer reaction at collision energies from over 1,000 K down to 20 mK have now been studied. At high energies a pronounced dependence of the reactivity on the reactant orientation is observed, but this effect is not present at the lowest energies because of dynamic reorientation.
- Sean D. S. Gordon
- , Juan J. Omiste
- & Andreas Osterwalder
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Non-intuitive rotational reorientation in collisions of NO(A 2Σ+) with Ne from direct measurement of a four-vector correlation
Measurements of vector correlations provide insight into the forces acting during molecular collisions, and are a stringent test of electronic-structure calculations. Now, non-intuitive dynamics of molecular collisions have been revealed by measuring the correlation between the relative velocities of the colliders and the molecular rotational angular momentum—before and after the collision—for NO(A 2Σ+) + Ne.
- Thomas R. Sharples
- , Joseph G. Leng
- & Matthew L. Costen