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Poly(ethylene terephthalate) (PET) is one of the most abundantly produced synthetic polymers and is accumulating in the environment at a staggering rate as discarded packaging and textiles. The properties that make PET so useful also endow it with an alarming resistance to biodegradation, likely lasting centuries in the environment. Our collective reliance on PET and other plastics means that this buildup will continue unless solutions are found. Recently, a newly discovered bacterium, Ideonella sakaiensis 201-F6, was shown to exhibit the rare ability to grow on PET as a major carbon and energy source. Central to its PET biodegradation capability is a secreted PETase (PET-digesting enzyme). Here, we present a 0.92 Å resolution X-ray crystal structure of PETase, which reveals features common to both cutinases and lipases. PETase retains the ancestral α/β-hydrolase fold but exhibits a more open active-site cleft than homologous cutinases. By narrowing the binding cleft via mutation of two active-site residues to conserved amino acids in cutinases, we surprisingly observe improved PET degradation, suggesting that PETase is not fully optimized for crystalline PET degradation, despite presumably evolving in a PET-rich environment. Additionally, we show that PETase degrades another semiaromatic polyester, polyethylene-2,5-furandicarboxylate (PEF), which is an emerging, bioderived PET replacement with improved barrier properties. In contrast, PETase does not degrade aliphatic polyesters, suggesting that it is generally an aromatic polyesterase. These findings suggest that additional protein engineering to increase PETase performance is realistic and highlight the need for further developments of structure/activity relationships for biodegradation of synthetic polyesters.

A bstract We study a notion of operator growth known as Krylov complexity in free and interacting massive scalar quantum field theories in d -dimensions at finite temperature. We consider the effects of mass, one-loop self-energy due to perturbative interactions, and finite ultraviolet cutoffs in continuous momentum space. These deformations change the behavior of Lanczos coefficients and Krylov complexity and induce effects such as the “staggering” of the former into two families, a decrease in the exponential growth rate of the latter, and transitions in their asymptotic behavior. We also discuss the relation between the existence of a mass gap and the property of staggering, and the relation between our ultraviolet cutoffs in continuous theories and lattice theories.

Nuclear charge radii globally scale with atomic mass number A as A 1∕3 , and isotopes with an odd number of neutrons are usually slightly smaller in size than their even-neutron neighbours. This odd–even staggering, ubiquitous throughout the nuclear landscape 1 , varies with the number of protons and neutrons, and poses a substantial challenge for nuclear theory 2 – 4 . Here, we report measurements of the charge radii of short-lived copper isotopes up to the very exotic 78 Cu (with proton number Z = 29 and neutron number N = 49), produced at only 20 ions s –1 , using the collinear resonance ionization spectroscopy method at the Isotope Mass Separator On-Line Device facility (ISOLDE) at CERN. We observe an unexpected reduction in the odd–even staggering for isotopes approaching the N = 50 shell gap. To describe the data, we applied models based on nuclear density functional theory 5 , 6 and A -body valence-space in-medium similarity renormalization group theory 7 , 8 . Through these comparisons, we demonstrate a relation between the global behaviour of charge radii and the saturation density of nuclear matter, and show that the local charge radii variations, which reflect the many-body polarization effects, naturally emerge from A -body calculations fitted to properties of A ≤ 4 nuclei. Isotopes with an odd number of neutrons are usually slightly smaller in size than their even-neutron neighbours. In charge radii of short-lived copper isotopes, a reduction of this effect is observed when the neutron number approaches fifty.

This study addressed a critical knowledge gap by examining the influence of staggering on the bond strength of lapped glass fiber-reinforced polymer (GFRP) bars in concrete members. It involved a comprehensive investigation of new-generation GFRP bars with varying staggering configurations in nine large-scale GFRP-reinforced concrete (RC) beams with a rectangular cross section of 300 x 450 mm (11.8 x 17.7 in.) and a length of 5200 mm (204.7 in.). The tests investigated splice strength with three staggering distances: 0, 1.0, and 1.3 times the splice length ([l.sub.s]) from center-to-center of two adjacent splices, and three splice lengths of 28, 38, and 45 times the bar diameter ([d.sub.b]). Results revealed a slight improvement in ultimate load-carrying capacity (less than 10%) for partially and fully staggered splices compared to non-staggered ones, with the latter exhibiting a more ductile failure mode. The effect of staggering was consistent across different splice lengths, demonstrating that splice length was not a factor. Although staggering reduced flexural crack width, it increased the total number of cracks due to expanded splice regions. Bond strength improved with staggering, with gains of 4.0% and 8.0% for partially and fully staggered splices, respectively. ACI CODE-440.11-22 provides more accurate predictions of the bond strength of lap-spliced GFRP bars than the other design codes, showing an average test-to-prediction ratio of 1.03 for non-staggered splices. Nevertheless, it requires some reconsiderations when it comes to staggered splices. To address this, a proposed modification factor was introduced to account for staggering conditions when calculating bond strength and splice length in ACI CODE-440.11-22. Keywords: bond strength; concrete structures; design codes; development length; glass fiber-reinforced polymer (GFRP) reinforcing bars; lap splicing; splice length; splice strength; staggering effect.

In rare cases, the removal of a single proton (Z) or neutron (N) from an atomic nucleus leads to a dramatic shape change. These instances are crucial for understanding the components of the nuclear interactions that drive deformation. The mercury isotopes (Z = 80) are a striking example1,2: their close neighbours, the lead isotopes (Z = 82), are spherical and steadily shrink with decreasing N. The even-mass (A = N + Z) mercury isotopes follow this trend. The odd-mass mercury isotopes 181,183,185Hg, however, exhibit noticeably larger charge radii. Due to the experimental difficulties of probing extremely neutron-deficient systems, and the computational complexity of modelling such heavy nuclides, the microscopic origin of this unique shape staggering has remained unclear. Here, by applying resonance ionization spectroscopy, mass spectrometry and nuclear spectroscopy as far as 177Hg, we determine 181Hg as the shape-staggering endpoint. By combining our experimental measurements with Monte Carlo shell model calculations, we conclude that this phenomenon results from the interplay between monopole and quadrupole interactions driving a quantum phase transition, for which we identify the participating orbitals. Although shape staggering in the mercury isotopes is a unique and localized feature in the nuclear chart, it nicely illustrates the concurrence of single-particle and collective degrees of freedom at play in atomic nuclei.

Water consumption dynamics lead to pressure fluctuations at network nodes, potentially associated with pipe leakages or unreliable supply within a water distribution system. Efficient management of secondary water supply system (SWSS) could enhance inflow modes of its essential component (i.e., storage tank) of potential implication on pressure control and water quality maintenance. In this study, a novel computational framework was developed to determine the optimal inflow profiles of storage tanks, where a water supply system simulation model was integrated with the particle swarm algorithm-based optimization for demand peak staggering. Experimental investigations on an example water supply system revealed that, as compared to the control of float ball valves, the optimizing regulation of SWSS tanks remarkably reduced water pressure oscillations by approximately 70%, correspondingly with the minimum pressure elevating and the maximum pressure declining among network nodes. Furthermore, the enhancing regulation schemes allowed water levels to fluctuate within an effective range, thus decreasing water retention time and facilitating associated water quality safety. Sensitivity analysis from our simulations indicates that increasingly appropriate tank number and size magnified the regulation capability, thereby reinforcing the promotion effect of optimizing control schemes on the system performance. The proposed approach is expected to provide theoretical support for optimizing the dynamic operations and management of SWSSs.

The February 2023 Turkey‐Syria Earthquake doublet ruptured multiple segments of the East Anatolian Fault (EAF) Zone. Dominating seismicity focal mechanism shifted dramatically from strike‐slip to normal‐faulting after the doublet. To better understand this shift, here we derived a comprehensive 3D co‐seismic displacement field and performed the stress analysis. Abundant space geodetic data were used to generate high‐resolution 3D surface displacement, which provide tight constraints on fault geometry, slip distribution and stress field. Together with stress inversion from aftershock focal mechanisms, we show that the principal stress direction rotation in the region with the most normal‐faulting aftershocks is the staggering 29°. The induced heterogenous stress may explain the shift of the dominant focal mechanism toward normal faulting. We suggest that the extensional horsetail splay faults, likely formed through geologic time scale related to the releasing bend on the EAF, are the hosts of most of the normal faulting aftershocks. Plain Language Summary Sudden dislocation of two sides of a fault, or the rupture of rocks, produces an earthquake. The dislocation direction relative to the fault traces reflects the direction of stress that are responsible for the earthquake. When dislocation direction is parallel to the fault strike, the earthquake is termed as strike‐slip type, and termed as normal‐faulting type when they are perpendicular. A remarkable feature for the 2023 Turkey‐Syria Mw7.8 & 7.7 earthquake doublet is that, background seismicity shifted dramatically from strike‐slip to normal type of faulting after the doublet. To unravel the physical process resulted in this feature, we use space geodetic measurements to derive the surface displacements and stress field associated with the doublet. The derived stress field shows a staggering 29° rotation occurred in a horsetail splay fault structure where many normal‐faulting earthquakes happened. The large stress rotation indicates the doublet released considerable stress and may result in a heterogeneous stress field due to the stress change. The combination of the identified horsetail structure and stress rotation can help better explain the occurrence of pervasive normal‐faulting earthquakes. Key Points We map the 3D displacements, slip distribution, and stress fields related to the 2023 Turkey‐Syria Earthquake doublet Dramatic stress rotation occurred after the Earthquake doublet, up to 29° Stress rotation and horsetail splay fault structure are potentially responsible for normal‐faulting aftershocks

The formulation of a fully compressible nonhydrostatic atmospheric model called the Model for Prediction Across Scales–Atmosphere (MPAS-A) is described. The solver is discretized using centroidal Voronoi meshes and a C-grid staggering of the prognostic variables, and it incorporates a split-explicit time-integration technique used in many existing nonhydrostatic meso- and cloud-scale models. MPAS can be applied to the globe, over limited areas of the globe, and on Cartesian planes. The Voronoi meshes are unstructured grids that permit variable horizontal resolution. These meshes allow for applications beyond uniform-resolution NWP and climate prediction, in particular allowing embedded high-resolution regions to be used for regional NWP and regional climate applications. The rationales for aspects of this formulation are discussed, and results from tests for nonhydrostatic flows on Cartesian planes and for large-scale flow on the sphere are presented. The results indicate that the solver is as accurate as existing nonhydrostatic solvers for nonhydrostatic-scale flows, and has accuracy comparable to existing global models using icosahedral (hexagonal) meshes for large-scale flows in idealized tests. Preliminary full-physics forecast results indicate that the solver formulation is robust and that the variable-resolution-mesh solutions are well resolved and exhibit no obvious problems in the mesh-transition zones.

The energies and B ( E 2) transitions involving the states of the ground- and γ -bands in thirty transitional and deformed nuclei are calculated using the triaxial projected shell model (TPSM) approach. Systematic good agreement with the existing data substantiates the reliability of the model predictions. The Gamma-rotor version of the collective Bohr Hamiltonian is discussed in order to quantify the classification with respect to the triaxial shape degree of freedom. The pertaining criteria are applied to the TPSM results and the staggering of the energies of the γ -bands is analyzed in detail. An analog staggering of the intra- γ B ( E 2 , I → I - 2 ) is introduced for the first time. The emergence of the staggering phenomena in the transitions is explained in the terms of interactions between the bands.