bluuebunny/crossref_metadata_2025 huggingface dataset:
The vibriophage-encoded inhibitor OrbA abrogates BREX-mediated defense through the ATPase BrxC
Authors: Oshiro Reid T , Dunham Drew T , Seed Kimberley D
Published: May 2024

Bacteria and phages are locked in a co-evolutionary arms race where each entity evolves mechanisms to restrict the proliferation of the other. Phage-encoded defense inhibitors have proven powerful tools to interrogate how defense systems function. A relatively common defense system is BREX (Bacteriophage exclusion); however, how BREX functions to restrict phage infection remains poorly understood. A BREX system encoded by the SXT integrative and conjugative element,VchInd5, was recently identified inVibrio cholerae, the causative agent of the diarrheal disease cholera. The lytic phage ICP1 that co-circulates withV. choleraeencodes the BREX inhibitor OrbA, but how OrbA inhibits BREX is unclear. Here, we determine that OrbA inhibits BREX using a unique mechanism from known BREX inhibitors by directly binding to the BREX component BrxC. BrxC has a functional ATPase domain that, when mutated, not only disrupts BrxC function but also alters how BrxC multimerizes. Furthermore, we find that OrbA binding disrupts BrxC-BrxC interactions. We determine that OrbA cannot bind BrxC encoded by the distantly related BREX system encoded by the SXTVchBan9, and thus fails to inhibit this BREX system that also circulates in epidemicV. cholerae. Lastly, we find that homologs of theVchInd5 BrxC are more diverse than the homologs of theVchBan9 BrxC. These data provide new insight into the function of the BrxC ATPase and highlight how phage-encoded inhibitors can disrupt phage defense systems using different mechanisms.

Importance

With renewed interest in phage therapy to combat antibiotic-resistant pathogens, understanding the mechanisms bacteria use to defend themselves against phages and the counter-strategies phages evolve to inhibit defenses is paramount. Bacteriophage exclusion (BREX) is a common defense system with few known inhibitors. Here, we probe how the vibriophage-encoded inhibitor OrbA inhibits the BREX system ofVibrio cholerae, the causative agent of the diarrheal disease cholera. By interrogating OrbA function, we have begun to understand the importance and function of a BREX component. Our results demonstrate the importance of identifying inhibitors against defense systems, as they are powerful tools for dissecting defense activity and can inform strategies to increase the efficacy of some phage therapies.
X-ray crystallographic analyses of 14 IPMK inhibitor complexes
Authors: Wang Huanchen , Blind Raymond D. , Shears Stephen B.
Published: May 2024

Inositol polyphosphate multikinase (IPMK) is a ubiquitously expressed kinase that has been linked to several cancers. Here, we report 14 new co-crystal structures (1.7Å - 2.0Å resolution) of human IPMK complexed with various IPMK inhibitors developed by another group. The new structures reveal two ordered water molecules that participate in hydrogen-bonding networks, and an unoccupied pocket in the ATP-binding site of human IPMK. New Protein Data Bank (PDB) codes of these IPMK crystal structures are:8V6W(1.95Å),8V6X(1.75Å),8V6Y(1.70Å),8V6Z(1.85Å),8V70(1.85Å),8V71(1.70Å),8V72(2.0Å),8V73(1.90Å),8V74(1.85Å),8V75(1.85Å),8V76(1.95Å),8V77(1.95Å),8V78(1.95Å),8V79(1.95Å).
Prediction of pathological subthalamic nucleus beta burst occurrence in Parkinson’s disease
Authors: Abdi-Sargezeh Bahman , Shirani Sepehr , Sharma Abhinav , Green Alexander , Akram Harith , Zrinzo Ludvic , Limousin Patricia , Foltynie Tom , Denison Timothy , Tan Huiling , Litvak Vladimir , Oswal Ashwini
Published: May 2024

The cortico-basal ganglia network in Parkinson’s disease (PD) is characterized by the emergence of transient episodes of exaggerated beta frequency oscillatory synchrony known as bursts. Although it is well established that bursts of prolonged duration associate closely with motor impairments, the mechanisms leading to burst initiation remain poorly understood. Crucially, it is unclear whether there are features of basal ganglia activity which reliably predict burst onset. Current adaptive Deep Brain Stimulation (aDBS) approaches can only reactively deliver stimulation following burst detection and are unable to stimulate proactively to prevent burst onset. The discovery of predictive biomarkers could allow for such proactive stimulation, thereby offering potential for improvements in therapeutic efficacy. Here, using deep learning, we show that the timing of subthalamic nucleus (STN) beta bursts can be accurately predicted up to 60 ms prior to onset. Furthermore, we highlight that a dip in the beta amplitude - which is likely to be indicative of a phase reset of oscillatory populations occurring between 80-100 ms prior to burst onset - is a predictive biomarker for burst occurrence. These findings demonstrate proof-of-principle for the feasibility of beta burst prediction for DBS and provide insights into the mechanisms of burst initiation.
Native β-barrel substrates pass through two shared intermediates during folding on the BAM complex
Authors: Santos Thiago M. A. , Thomson Benjamin D. , Marquez Melissa D. , Pan Lydia , Monfared Tabasom H , Kahne Daniel E.
Published: May 2024

The assembly of β-barrel proteins into membranes is mediated by the evolutionarily conserved BAM complex. InEscherichia coli, BAM folds numerous substrates which vary considerably in size and shape. How BAM is able to efficiently fold such a diverse array of β-barrel substrates is not clear. Here, we develop a disulfide crosslinking method to trap native substrates in vivo as they fold on BAM. By placing a cysteine within the luminal wall of the BamA barrel as well as in the substrate β-strands, we can compare the residence time of each substrate strand within the BamA lumen. We validated this method using two defective, slow-folding substrates. We used this method to characterize stable intermediates which occur during folding of two structurally different native substrates. Strikingly, these intermediates occur during identical stages of folding for both substrates: soon after folding has begun, and just before folding is completed. We suggest that these intermediates arise due to barriers to folding that are common between β-barrel substrates, and that the BAM catalyst is able to fold so many different substrates because it addresses these common challenges.

Significance Statement

The outer membrane of Gram-negative bacteria is a barrier which protects these organisms from many antimicrobial agents. Here, we study the machine responsible for folding and inserting integral β-barrel proteins into the membrane: BAM. Outer membrane integrity and cell viability is dependent on the proper function of BAM. Here we show that stable intermediates exist on the folding pathway of native substrates. We also show that mutant substrates that increase the stability of these native intermediates can stall during folding. This creates permeability defects that can be exploited by antibiotics that normally do not cross the outer membrane. These observations could enable the design of strategies to combat Gram-negative pathogens.
Structural basis for catalysis and selectivity of phospholipid synthesis by eukaryotic choline-phosphotransferase
Authors: Roberts Jacquelyn R. , Horibata Yasuhiro , Kwarcinski Frank E. , Lam Vinson , Raczkowski Ashleigh M. , Hubbard Akane , White Betsy , Sugimoto Hiroyuki , Tall Gregory G. , Ohi Melanie D. , Maeda Shoji
Published: May 2024

Phospholipids are the most abundant component in lipid membranes and are essential for the structural and functional integrity of the cell. In eukaryotic cells, phospholipids are primarily synthesizedde novothrough the Kennedy pathway that involves multiple enzymatic processes. The terminal reaction is mediated by a group of cytidine-5’-diphosphate (CDP)-choline /CDP-ethanolamine-phosphotransferases (CPT/EPT) that use 1,2-diacylglycerol (DAG) and CDP-choline or CDP-ethanolamine to produce phosphatidylcholine (PC) or phosphatidylethanolamine (PE) those are the main phospholipids in eukaryotic cells. Here we present the structure of the yeast CPT1 in multiple substrate-bound states. Structural and functional analysis of these binding-sites reveal the critical residues for the DAG acyl-chain preference and the choline/ethanolamine selectivity. Additionally, we present the structure in complex with a potent inhibitor characterized in this study. The ensemble of structures allows us to propose the reaction mechanism for phospholipid biosynthesis by the family of CDP-alcohol phosphatidyltransferases (CDP-APs).
Classification of classical spin liquids: Detailed formalism and suite of examples
Authors: Yan Han , Benton Owen , Nevidomskyy Andriy H. , Moessner Roderich
Published: May 2024

The hallmark of highly frustrated systems is the presence of many states close in energy to the ground state. Fluctuations between these states can preclude the emergence of any form of order and lead to the appearance of spin liquids. Even on the classical level, spin liquids are not all alike: they may have algebraic or exponential correlation decay, and various forms of long wavelength description, including vector or tensor gauge theories. Here, we introduce a classification scheme, allowing us to fit the diversity of classical spin liquids (CSLs) into a general framework as well as predict and construct new kinds. CSLs with either algebraic or exponential correlation-decay can be classified via the properties of the bottom flat band(s) in their soft-spin Hamiltonians. The classification of the former is based on the algebraic structures of gapless points in the spectra, which relate directly to the emergent generalized Gauss's laws that control the low-temperature physics. The second category of CSLs, meanwhile, are classified by the fragile topology of the gapped bottom band(s). Utilizing the classification scheme we construct new models realizing exotic CSLs, including one with anisotropic generalized Gauss's laws and charges with subdimensional mobility, one with a network of pinch-line singularities in its correlation functions and a series of fragile topological CSLs connected by zero-temperature transitions.

Published by the American Physical Society
2024
Effective theory for graphene nanoribbons with junctions
Authors: Ostmeyer Johann , Razmadze Lado , Berkowitz Evan , Luu Thomas , Meißner Ulf-G.
Published: May 2024

Graphene nanoribbons are a promising candidate for fault-tolerant quantum electronics. In this scenario, qubits are realized by localized states that can emerge on junctions in hybrid ribbons formed by two armchair nanoribbons of different widths. We derive an effective theory based on a tight-binding ansatz for the description of hybrid nanoribbons and use it to make accurate predictions of the energy gap and nature of the localization in various hybrid nanoribbon geometries. We use quantum Monte Carlo simulations to demonstrate that the effective theory remains applicable in the presence of Hubbard interactions. We discover, in addition to the well-known localizations on junctions, which we call “Fuji”, a new type of “Kilimanjaro” localization smeared out over a segment of the hybrid ribbon. We show that Fuji localizations in hybrids of width N and N+2 armchair nanoribbons occur around symmetric junctions if and only if N(mod3)=1, while edge-aligned junctions never support strong localization. This behavior cannot be explained relying purely on the topological Z2 invariant, which has been believed to be the origin of the localizations to date.

Published by the American Physical Society
2024
QGSJET-III model of high energy hadronic interactions. II. Particle production and extensive air shower characteristics
Authors: Ostapchenko Sergey
Published: May 2024

The hadronization procedure of the QGSJET-III Monte Carlo (MC) generator of high energy hadronic interactions is discussed. Selected results of the model, regarding production spectra of secondary particles, are presented in comparison to experimental data and to the corresponding predictions of the QGSJET-II-04 MC generator. The model is applied to calculations of basic characteristics of extensive air showers initiated by cosmic ray interactions in the atmosphere and the results are compared to predictions of other MC generators of cosmic ray interactions.

Published by the American Physical Society
2024
Parton distributions from boosted fields in the Coulomb gauge
Authors: Gao Xiang , Liu Wei-Yang , Zhao Yong
Published: May 2024

We propose a new method to calculate parton distribution functions (PDFs) from lattice correlations of boosted quarks and gluons in the Coulomb gauge. Compared to the widely used gauge-invariant Wilson-line operators, these correlations greatly simplify the renormalization thanks to the absence of linear power divergence. Additionally, they enable access to larger off-axis momenta under preserved 3D rotational symmetry, as well as enhanced long-range precision that facilitates the Fourier transform. We verify the factorization formula that relates this new observable to the quark PDF at one-loop order in perturbation theory. Moreover, through a lattice calculation of the pion valence quark PDF, we demonstrate the aforementioned advantage and features of the Coulomb gauge correlation and show that it yields consistent results with the gauge-invariant method. This opens the door to a more efficient way to calculate parton physics on the lattice.

Published by the American Physical Society
2024
Minimal SU(5) theory on the edge: The importance of being effective
Authors: Senjanović Goran , Zantedeschi Michael
Published: May 2024

It is well known that the minimal renormalizable SU(5) grand unified theory is ruled out: it predicts the same masses of down quarks and charged leptons, the gauge couplings do not unify, and neutrinos are massless. We show here that all this can be cured simultaneously by the addition of higher-dimensional effective operators. However, the theory lives on the edge since the unification scale turns out as low as roughly 1014  GeV, threatening proton longevity. If the lower bound on the proton lifetime was to be increased by an order of magnitude, the usual desert in energies between the weak and unification scales would be populated. We also revisit two minimal extensions of this theory that offer a dynamical seesaw origin of neutrino mass and discuss the resulting consequences.

Published by the American Physical Society
2024
Low-mass dark sector searches with deuteron photodisintegration
Authors: Mommers Cornelis J. G. , Vanderhaeghen Marc
Published: May 2024

Recent years have seen much activity in searches for dark-sector messenger particles in the 10–100 MeV mass range, especially in view of a potential new light boson conjectured by the ATOMKI Collaboration, X17. Under the assumption that the messenger particle has definite parity and either zero or unit spin, quite stringent bounds already exist on its coupling to electrons and protons. Equally stringent bounds on the neutron coupling do not exist yet, but are nonetheless desirable. We explore how measurements of deuteron photodisintegration with a quasifree neutron can yield bounds on the neutron coupling, and compute projections for a potential measurement at the low-energy high-intensity electron scattering experiment MAGIX@MESA. The projected bounds are found to be competitive for an axial-vector or pseudoscalar scenario, but not for a vector or scalar scenario.

Published by the American Physical Society
2024
Quantum electrodynamics mediated by a photon with continuous spin
Authors: Schuster Philip , Toro Natalia
Published: May 2024

In recent work with Zhou, we studied classical interactions of matter with a “continuous spin” field, whose excitations have zero mass but nonzero spin Casimir (spin scale) ρ. We reported evidence that such theories are a calculable infrared deformation of familiar massless theories including electromagnetism. Building on the aforementioned work, this paper presents rules for computing scattering amplitudes involving charged scalar matter and continuous spin photons with nonzero spin scale. As a concrete example, we compute the pair annihilation and Compton scattering amplitudes in this theory and comment on their physical properties, including unitarity and scaling behavior at small and large ρ. Like the classical physics and soft factors studied in prior work, these amplitudes exhibit “helicity correspondence,” recovering familiar amplitudes at energy scales ≫ρ, but with calculable deviations that could be experimentally tested. These results bolster the conjecture that continuous spin particles with a very small ρ could mediate long-range forces in nature (e.g., the photon could be a continuous spin particle), and extend the range of physical effects that could be used to test this hypothesis.

Published by the American Physical Society
2024
Unraveling generalized parton distributions through Lorentz symmetry and partial DGLAP knowledge
Authors: Dall’Olio P. , De Soto F. , Mezrag C. , Morgado Chávez J. M. , Moutarde H. , Rodríguez-Quintero J. , Sznajder P. , Segovia J.
Published: May 2024

Relying on the polynomiality property of generalized parton distributions, which roots on Lorentz covariance, we prove that it is enough to know them at vanishing and low skewness within the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi region to obtain a unique extension to their entire support up to a D term. We put this idea in practice using two methods: reconstruction using artificial neural networks and finite-elements methods. We benchmark our results against standard models for generalized parton distributions. In agreement with the formal expectation, we obtain very a accurate reconstruction for a maximal value of the skewness as low as 20% of the longitudinal momentum fraction. This result might be relevant for reconstruction of generalized parton distribution from experimental and lattice QCD data, where computations are, for now, restricted in skewness.

Published by the American Physical Society
2024
Perturbations of spinning black holes in dynamical Chern-Simons gravity: Slow rotation equations
Authors: Wagle Pratik , Li Dongjun , Chen Yanbei , Yunes Nicolás
Published: May 2024

The detection of gravitational waves resulting from the coalescence of binary black holes by the LIGO-Virgo-Kagra Collaboration has inaugurated a new era in gravitational physics. These gravitational waves provide a unique opportunity to test Einstein’s general relativity and its modifications in the regime of extreme gravity. A significant aspect of such tests involves the study of the ringdown phase of gravitational waves from binary black hole coalescence, which can be decomposed into a superposition of various quasinormal modes. In general relativity, the spectra of quasinormal modes depend on the mass, spin, and charge of the final black hole, but they can also be influenced by additional properties of the black hole spacetime, as well as corrections to the general theory of relativity. In this work, we focus on a specific modified theory known as dynamical Chern-Simons gravity. We employ the modified Teukolsky formalism developed in a previous study and lay down the foundations to investigate perturbations of slowly rotating black holes admitted by the theory. Specifically, we derive the master equations for the Ψ0 and Ψ4 Weyl scalar perturbations that characterize the radiative part of gravitational perturbations, as well as the master equation for the scalar field perturbations. We employ metric reconstruction techniques to obtain explicit expressions for all relevant quantities. Finally, by leveraging the properties of spin-weighted spheroidal harmonics to eliminate the angular dependence from the evolution equations, we derive two, radial, second-order, ordinary differential equations for Ψ0 and Ψ4, respectively. These two equations are coupled to another radial, second-order, ordinary differential equation for the scalar field perturbations. This work is the first attempt to derive a master equation for black holes in dynamical Chern-Simons gravity using curvature perturbations. The master equations we obtain can then be numerically integrated to obtain the quasinormal mode spectrum of slowly rotating black holes in this theory, making progress in the study of ringdown in dynamical Chern-Simons gravity.

Published by the American Physical Society
2024
Setting the connection free in the Galilei and Carroll expansions of gravity
Authors: Musaeus Jørgen , Obers Niels A. , Oling Gerben
Published: May 2024

We obtain a Palatini-type formulation for the Galilei and Carroll expansions of general relativity, where the connection is promoted to a variable. Known versions of these large and small speed of light expansions are derived from the Einstein-Hilbert action and involve dynamical Newton-Cartan or Carroll geometry, along with additional gauge fields at subleading orders. The corresponding Palatini actions that we obtain in this paper are derived from an appropriate expansion of the Einstein-Palatini action, and the connection variable reduces to the Galilei- or Carroll-adapted connection on shell. In particular, we present the Palatini form for the next-to-leading-order Galilean action and recover the known equations of motion. We also compute the leading-order Palatini-type action for the Carrollian case and show that, while it depends on the connection variable, it reduces on shell to the known action of electric Carroll gravity, which only depends on extrinsic curvature.

Published by the American Physical Society
2024
Fermions, quantum gravity, and holography in two dimensions
Authors: Asaduzzaman Muhammad , Catterall Simon , Samlodia Abhishek
Published: May 2024

We study a model comprising N flavors of Kähler Dirac fermion propagating on a triangulated two-dimensional disk which is constrained to have a negative average bulk curvature. Dirichlet boundary conditions are chosen for the fermions. Quantum fluctuations of the geometry are included by summing over all possible triangulations consistent with these constraints. We show in the limit N→∞ that the partition function is dominated by a regular triangulation of two-dimensional hyperbolic space. We use strong coupling expansions and Monte Carlo simulation to show that in this limit boundary correlators of the fermions have a power law dependence on boundary separation as one expects from holography. However, we argue that this behavior breaks down for any finite number of massive fields in the thermodynamic limit and quantum fluctuations of the bulk geometry drive the theory into a nonholographic phase. In contrast, for massless fermions, we find evidence that the boundary is conformal even for finite N. This is consistent with theoretical results in quantum Liouville theory.

Published by the American Physical Society
2024
Holography of linear dilaton spacetimes from the bottom up
Authors: Fichet Sylvain , Megías Eugenio , Quirós Mariano
Published: May 2024

The linear dilaton (LD) background is the keystone of a string-derived holographic correspondence beyond AdSd+1/CFTd. This motivates an exploration of the (d+1)-dimensional linear dilaton spacetime (LDd+1) and its holographic properties from the low-energy viewpoint. We first notice that the LDd+1 space has simple conformal symmetries, that we use to shape an effective field theory (EFT) on the LD background. We then place a brane in the background to study holography at the level of quantum fields and gravity. We find that the holographic correlators from the EFT feature a pattern of singularities at certain kinematic thresholds. We argue that such singularities can be used to bootstrap the putative d-dimensional dual theory using techniques analogous to those of the cosmological bootstrap program. Turning on finite temperature, we study the holographic fluid emerging on the brane in the presence of a bulk black hole. We find that the holographic fluid is pressureless for any d due to a cancellation between Weyl curvature and dilaton stress tensor, and verify consistency with the time evolution of the theory. From the fluid thermodynamics, we find a universal temperature and Hagedorn behavior for any d. This matches the properties of a CFT2 with large TT¯ deformation, and of little string theory for d=6. We also find that the holographic fluid entropy exactly matches the bulk black hole Bekenstein-Hawking entropy. Both the fluid equation of state and the spectrum of quantum fluctuations suggest that the d-dimensional dual theory arising from LDd+1 is generically gapped.

Published by the American Physical Society
2024
Holographic entropy inequalities and the topology of entanglement wedge nesting
Authors: Czech Bartłomiej , Shuai Sirui , Wang Yixu , Zhang Daiming
Published: May 2024

We prove two new infinite families of holographic entropy inequalities. A key tool is a graphical arrangement of terms of inequalities that is based on entanglement wedge nesting. It associates the inequalities with tessellations of the torus and the projective plane, which reflect a certain topological aspect of entanglement wedge nesting. The inequalities prove a prior conjecture about the holographic entropy cone. We discuss their relation to black hole physics and differential entropy, and sketch applications to quantum error correction, quantifying randomness of quantum states, and others.

Published by the American Physical Society
2024
Slender phoretic loops and knots
Authors: Katsamba Panayiota , Butler Matthew D. , Koens Lyndon , Montenegro-Johnson Thomas D.
Published: May 2024

We present an asymptotic theory for solving the dynamics of slender autophoretic loops and knots. Our formulation is valid for nonintersecting three-dimensional center lines, with arbitrary chemical patterning and varying (circular) cross-sectional radius, allowing a broad class of slender active loops and knots to be studied. The theory is amenable to closed-form solutions in simpler cases, allowing us to analytically derive the swimming speed of chemically patterned tori, and the pumping strength (stresslet) of a uniformly active slender torus. Using simple numerical solutions of our asymptotic equations, we then elucidate the behavior of many exotic active particle geometries, such as a bumpy uniformly active torus that spins and a Janus trefoil knot, which rotates as it swims forwards.

Published by the American Physical Society
2024
Multi-GeV Electron Acceleration in Wakefields Strongly Driven by Oversized Laser Spots
Authors: Põder K. , Wood J. C. , Lopes N. C. , Cole J. M. , Alatabi S. , Backhouse M. P. , Foster P. S. , Hughes A. J. , Kamperidis C. , Kononenko O. , Mangles S. P. D. , Palmer C. A. J. , Rusby D. , Sahai A. , Sarri G. , Symes D. R. , Warwick J. R. , Najmudin Z.
Published: May 2024

Experiments were performed on laser wakefield acceleration in the highly nonlinear regime. With laser powers P<250  TW and using an initial spot size larger than the matched spot size for guiding, we were able to accelerate electrons to energies Emax>2.5  GeV, in fields exceeding 500  GV m−1, with more than 80 pC of charge at energies E>1  GeV. Three-dimensional particle-in-cell simulations show that using an oversized spot delays injection, avoiding beam loss as the wakefield undergoes length oscillation. This enables injected electrons to remain in the regions of highest accelerating fields and leads to a doubling of energy gain as compared to results from using half the focal length with the same laser.

Published by the American Physical Society
2024
Simulating Open Quantum Systems Using Hamiltonian Simulations
Authors: Ding Zhiyan , Li Xiantao , Lin Lin
Published: May 2024

We present a novel method to simulate the Lindblad equation, drawing on the relationship between Lindblad dynamics, stochastic differential equations, and Hamiltonian simulations. We derive a sequence of unitary dynamics in an enlarged Hilbert space that can approximate the Lindblad dynamics up to an arbitrarily high order. This unitary representation can then be simulated using a quantum circuit that involves only Hamiltonian simulation and tracing out the ancilla qubits. There is no need for additional postselection in measurement outcomes, ensuring a success probability of one at each stage. Our method can be directly generalized to the time-dependent setting. We provide numerical examples that simulate both time-independent and time-dependent Lindbladian dynamics with accuracy up to the third order.

Published by the American Physical Society
2024
Supramolecular synthons in hydrates and solvates of lamotrigine: a tool for cocrystal design
Authors: Pavlović Gordana , Lekšić Edislav , Meštrović Ernest
Published: May 2024

The molecule of anti-epileptic drug lamotrigine [LAM; 3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine] is capable of the formation of multicomponent solids. Such an enhanced tendency is related to the diverse functionalities of the LAM chemical groups able to form hydrogen bonds. Two robust synthons are recognized in the supramolecular structure of LAM itself formed via N—H...N hydrogen bond: homosynthon, so-called aminopyridine dimer or synthon 1 [R
2
2(8)] and larger homosynthon 2 [R
3
2(8)]. The synthetic procedures for a new hydrate and 11 solvates of LAM (in the series: with acetone, ethanol: two polymorphs: form I and form II, 2-propanol, n-butanol, tert-butanol, n-pentanol, benzonitrile, acetonitrile, DMSO and dioxane) were performed. The comparative solid state structural analysis of a new hydrate and 11 solvates of LAM has been undertaken in order to establish robustness of the supramolecular synthons 1 and 2 found in the crystal structure of LAM itself as well as LAM susceptibility to build methodical solid state supramolecular architecture in the given competitive surrounding of potential hydrogen bonds. The aminopyridine dimer homosynthon 1 [R
2
2(8)] has been switched from para-para (P-P) topology to ortho-ortho (O-O) topology in all crystal structures, except in LAM:n-pentanol:water solvate where it remains P-P. Homosynthon 2 [R
3
2(8)] of the LAM crystal structure imitates in the LAM solvates as a heterosynthon by replacing the triazine nitrogen proton acceptor atoms of LAM with the proton acceptors of solvates molecules.
Bis(2-chloro-N,N-dimethylethan-1-aminium) tetrachloridocobaltate(II) and tetrachloridozincate(II)
Authors: McGinness Katelyn , Minton Kim , White Katelyn , Bond Marcus R.
Published: May 2024

The few examples of structures containing the 2-chloro-N,N-dimethylethan-1-aminium or 3-chloro-N,N-dimethylpropan-1-aminium cations show a competition between gauche and anti conformations for the chloroalkyl chain. To explore further the conformational landscape of these cations, and their possible use as molecular switches, the title salts, (C4H11ClN)2[CoCl4] and (C4H11ClN)2[ZnCl4], were prepared and structurally characterized. Details of both structures are in close agreement. The inorganic complex exhibits a slightly flattened tetrahedral geometry that likely arises from bifurcated N—H hydrogen bonds from the organic cations. The alkyl chain of the cation is disordered between gauche and anti conformations with the gauche conformation occupancy refined to 0.707 (2) for the cobaltate. The gauche conformation places the terminal Cl atom at a tetrahedral face of the inorganic complex with a contact distance of 3.7576 (9) Å to the Co2+ center. The anti conformation places the terminal Cl atom at a contact distance to a neighboring anti conformation terminal Cl atom that is ∼1 Å less than the sum of the van der Waals radii. Thus, if the anti conformation is present at a site, then the nearest neighbor must be gauche. DFT geometry optimizations indicate the gauche conformation is more stable in vacuo by 0.226 eV, which reduces to 0.0584 eV when calculated in a uniform dielectric. DFT geometry optimizations for the unprotonated molecule indicate the anti conformation is stabilized by 0.0428 eV in vacuo, with no strongly preferred conformation in uniform dielectric, to provide support to the notion that this cation could function as a molecular switch via deprotonation.
Crystal structure and Hirshfeld surface analysis of (Z)-4-oxo-4-{phenyl[(thiophen-2-yl)methyl]amino}but-2-enoic acid
Authors: Podrezova Alexandra G. , Nikitina Eugeniya V. , Grigoriev Mikhail S. , Akkurt Mehmet , Hasanov Khudayar I. , Sadikhova Nurlana D. , Bhattarai Ajaya
Published: May 2024

In the title compound, C15H13NO3S, the molecular conformation is stable with the intramolecular O—H...O hydrogen bond forming a S(7) ring motif. In the crystal, molecules are connected by C—H...O hydrogen bonds, forming C(8) chains running along the a-axis direction. Cohesion of the packing is provided by weak van der Waals interactions between the chains. A Hirshfeld surface analysis was undertaken to investigate and quantify the intermolecular interactions. The thiophene ring is disordered in a 0.9466 (17):0.0534 (17) ratio over two positions rotated by 180°.
The art of living together: space mining ecosystem, sustainability and accountability
Authors: Lee Yeolan , Fong Eric A.
Published: May 2024

Purpose

A major obstacle regarding the measurement of an organization's sustainability and accountability in the space economy is defining the context and boundaries of commercial activity in outer space. Here, we introduce an ecosystem framework to address this obstacle. We utilize this framework to analyze the space mining sector. Our ecosystem framework sets the space mining sector's boundaries and helps a firm identify key stakeholders, activities, policies, norms and common pool resources in that sector and the interactions between them; a significant step in structuring how to measure space sustainability and accountability.

Design/methodology/approach

Borrowing theories and perspectives from a wide range of academic fields, this paper conducts a comprehensive context analysis of the space mining ecosystem.

Findings

Using our ecosystem framework to define the context and set boundaries for the space mining sector allowed us to identify sustainability-related issues in the sector and offer roadmaps to develop sustainability measures and standards.

Originality/value

To the best of the authors’ knowledge, this is one of the first papers to introduce a framework to define boundaries in the global space economy and provides a tool to understand, measure and evaluate the space mining sector's environmental, social and economic issues.
Assessing the predictive validity of brand-sustainability-self-congruence on consumer behavior and subjective well-being
Authors: Kumagai Ken
Published: May 2024

Purpose

This research extends self-congruity theory and assesses the predictive validity of the triad personality congruence among brand, brand-related sustainability initiatives (BSI) and self-concept (BSSC: brand-sustainability-self-congruence) on consumers’ brand evaluation.

Design/methodology/approach

Three studies assessed BSSC using the brand personality scale (BPS) and the direct congruence measure (DCM). Through moderated mediation analyses, BSSC effects were examined on consumers’ behavioral intention, behavior and subjective well-being (SWB). The mediating role of brand trust and the moderating role of brand/BSI types and consumer characteristics were also assessed.

Findings

BSSC increased consumers’ brand trust, behavioral intention, behavior and SWB. Data based on BPS revealed impactful attributes that increase/decrease BSSC levels across brand-BSI combinations and the moderating role of sustainability involvement and income to enhance BSSC effects. BSSC was particularly effective, according to DCM.

Practical implications

For BSI planning, strategic consideration of BSSC based on both BPS and DCM is recommended. Thus, managers may predict the psychological impact of BSI and align its attributes to increase consumers’ brand evaluation.

Originality/value

In the sustainable marketing context, this research discusses BSSC – triad personality congruence – based on BPS and DCM and its predictive effects on consumers’ short-term brand evaluation, their actual behavior and SWB, a long-term life evaluation. The results imply a possible variation in consumers’ information processing according to the congruence measurement approach. Thus, it is relevant to the research on self-congruity, sustainability, marketing, consumer psychology/behavior and well-being.
Vulnerability, resilience and empowerment: the tripartite typology for addressing modern slavery in global value chains
Authors: Kubacki Krzysztof , Szablewska Natalia , Siemieniako Dariusz , Brennan Linda
Published: May 2024

Purpose

Modern slavery in global value chains is an emerging topic of interest across various fields, including in international business, but is often fragmented in its approach. This study aims to provide a practical framework for studying relationships between participants in global value chains by exploring the nexus of three concepts – vulnerability, resilience and empowerment (VRE) – in the context of modern slavery.

Design/methodology/approach

This article offers a deductive thematic analysis of 51 empirical and conceptual business research studies on modern slavery in global value chains published until mid-2021 according to the three categories of interest at the micro (within individuals and organisations), meso (between individuals and organisations) and macro (structural) levels.

Findings

The findings have informed the development of three themes, each of which is an opportunity for future research with clear policy implications: a reductionist approach to vulnerability obscures its complexity; externalising the empowerment process and locating it outside of the agency of workers serves to further disempower them; and focusing exclusively on organisational resilience conceals the essentiality of resilience within individuals, communities and societies.

Originality/value

This article is among the first to extend the focus of business literature on modern slavery in global value chains beyond its current largely facile engagement with VRE, offering an original descriptive VRE typology to engage with the nexus between these three concepts.
Evaluating the Kuznets curve relationship between economic growth and child labor in an emerging economy
Authors: Khan Muhammad Zubair , Khan Ismail , Ahmed Zeeshan , Khattak Muhammad Sualeh , Afridi Muhammad Asim
Published: May 2024

Purpose

This study aims to test the Kuznets curve between economic growth and child labor, along with the influence of exports, household size and rural population in the context of Pakistan.

Design/methodology/approach

To achieve the research objective, this study applied the unit root test, bound co-integration test, and autoregressive distributive lags (ARDL) method for the period of 1972–2021.

Findings

The findings show an inverted U-shaped relationship between economic growth and child labor indicating that at the beginning stage of economic development, child labor increases due to lower per capita household and subsequently, in the long-run of economic development, child labor decreases due to the higher per capita households. Moreover, the results also show that exports, household size and rural population have a positive influence on increasing child labor.

Research limitations/implications

The policymakers and government of Pakistan need to focus on long-term economic growth policies, ensure free quality education and cheap equipment which practices minimum manpower to reduce the threat of child labor.

Social implications

Having long-run economic growth, the government of Pakistan need to equally benefit the households and the poor population to reduce child labor and enhance the social welfare of society.

Originality/value

To the best of the authors’ knowledge, this is the first study that investigates the Kuznets curve relationship between economic growth and child labor in the context of Pakistan. Moreover, this study contributes to the reduction in child labor through long-term economic growth in the context of Pakistan.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/IJSE-05-2023-0387
Whistleblowing academic research: historical perspective
Authors: Arroyo Paulina , Smaili Nadia
Published: May 2024

Purpose

For more than four decades, scholars from diverse disciplines and countries have been interested in the act of whistleblowing. To battle financial fraud, financial regulators have been developing whistleblowing programs to motivate and protect whistleblowers, i.e. those who sound the alarm after witnessing an illegal act in their organization. The purpose of this article is to review five historical phases of whistleblowing research. The authors analyze the themes covered by whistleblowing studies conducted over the past 50 years and draw a snapshot of the evolution of whistleblowing research.

Design/methodology/approach

The authors examine academic papers published between 1970 and 2022 and inventory the disciplines involved in the literature and changes in the definition of whistleblowing.

Findings

The findings show the progress made in academic research (especially for the accounting discipline) regarding whistleblowing. The themes covered by academic studies became progressively diverse. However, this broader scope limited the depth of analysis and the level of self-criticism in the academic research. All but a few articles fail to view whistleblowing in light of its actual level of complexity, and the rationale behind limiting the definition of whistleblowing can only increase this myopia. Although most academic studies have adopted Near and Miceli (1985) definition of whistleblowing, the literature has yet to reach a consensus. Indeed, the analysis shows that Near and Miceli’s (1985) definition of whistleblowing is incomplete and narrow by today’s standards, not to mention out of step with regulators’ needs.

Originality/value

The main contributions are offering a big picture of whistleblowing academic research's evolution and proposing a more complete and updated view of this act.
Knowledge sharing between project creators and backers in rewards-based crowdfunding
Authors: Malhotra Arvind , Burtch Gordon , Wareham Jonathan
Published: May 2024

Purpose

In the context of rewards-based crowdfunding, this study aims to examine the role of project backers as providers of knowledge inputs beyond just financial capital.

Design/methodology/approach

This study uses binomial regression to study the relationship between project creators’ and backers’ knowledge sharing, and the relationship of these two knowledge-sharing elements with achieving above-goal funding levels.

Findings

This study finds that the project creator’s knowledge sharing is significantly and positively related to backers’ knowledge sharing and that this relationship is moderated by the type of project. Furthermore, backers’ knowledge sharing is positively related to above-goal funding outcomes for a project.

Research limitations/implications

This study established the link between creators’ and backers’ knowledge sharing in rewards-based crowdfunding, which has been underexplored in the literature. This study’s direct attention to the role of knowledge as a key resource in rewards-based crowdfunding and crowdsourcing in general.

Practical implications

For entrepreneurs seeking crowdfunding, this study highlights the importance of knowledge sharing with their project backers to attain above-goal funding. Furthermore, eliciting backers’ knowledge input acts as a signaling mechanism that increases the crowd’s confidence in the project. It also endows entrepreneurs with knowledge resources that can improve project outcomes and achieve broader market success postcrowdfunding.

Originality/value

To the best of the authors’ knowledge, this study is one of the first to focus on knowledge content as a critical element in project backer-creator communication in rewards-based crowdfunding. This study also delineate the various knowledge types shared between the project creator and backers in both rewards-based crowdfunding projects.
System dynamics applied in enterprise engineering – a systematic literature review
Authors: Hussain Huda , De Vries Marne
Published: May 2024

Purpose

This study aims to investigate the combined use of System Dynamics (SD) applications in Enterprise Engineering (EE) research and practice. SD application in EE is becoming widely accepted as a tool to support decision-making processes and for capturing relationships within enterprises.

Design/methodology/approach

A systematic literature review (SLR) is conducted using a standard SLR method to provide a comprehensive review of existing literature. The search was conducted on ten platforms identifying 30 publications which were analysed through the use and development of a codebook.

Findings

The SLR showed that 90% of the result set consisted of peer-reviewed academic conferences and journal papers. The SLR identified a highly dispersed author set of 83 authors. Amongst these authors, Vinay Kulkarni was an active author who has co-authored up to four publications in this research area. The analysis further revealed that the combined use of SD applications and EE is an emerging research area that still needs to develop in maturity. While all phases of EE have received attention, the current research work is more focused on the design phase. The important gap between model development and implementation is identified.

Originality/value

The study elucidates the existing status of interdisciplinary research combining techniques from the SD and EE disciplines, suggesting future research topics that combine the strengths of these existing disciplines.
The International Sustainability Standards Board’s (ISSB) past, present, and future: critical reflections and a research agenda
Authors: de Villiers Charl , Dimes Ruth , La Torre Matteo , Molinari Matteo
Published: May 2024

Purpose

This paper aims to critically reflect on the formation of the International Sustainability Standards Board (ISSB), its current agenda and likely future direction. The authors consider the relationships between the ISSB and other standard setters, regulators, practitioners and stakeholders, and develop a comprehensive research agenda.

Design/methodology/approach

The authors review and critically analyse academic and practitioner publications alongside the ISSB’s workplans to identify the themes impacting the future of the ISSB and to develop a research agenda.

Findings

Three key themes emerge from the authors’ analysis that are likely to influence the future of the ISSB: the jurisdiction and scope of the ISSB – how far its influence is likely to extend, both geographically and conceptually; the ongoing legitimacy challenge the ISSB is facing in terms of setting an agenda for sustainability reporting; and the “capture” of sustainability reporting by influential stakeholders including capital providers.

Originality/value

The formation of the ISSB is critical to the future of sustainability reporting. The authors provide a comprehensive and topical overview of the past, present and potential future of the ISSB, highlighting the need for further research and providing a research agenda that addresses outstanding questions in the field.