Dynamic Disorder Research Articles

Disulfide-Bond-Induced Structural Frustration and Dynamic Disorder in a Peroxiredoxin from MAS NMR.

Disulfide bond formation is fundamentally important for protein structure and constitutes a key mechanism by which cells regulate the intracellular oxidation state. Peroxiredoxins (PRDXs) eliminate reactive oxygen species such as hydrogen peroxide through a catalytic cycle of Cys oxidation and reduction. Additionally, upon Cys oxidation PRDXs undergo extensive conformational rearrangements that may underlie their presently structurally poorly defined functions as molecular chaperones. Rearrangements include high molecular-weight oligomerization, the dynamics of which are, however, poorly understood, as is the impact of disulfide bond formation on these properties. Here we show that formation of disulfide bonds along the catalytic cycle induces extensive μs time scale dynamics, as monitored by magic-angle spinning NMR of the 216 kDa-large Tsa1 decameric assembly and solution-NMR of a designed dimeric mutant. We ascribe the conformational dynamics to structural frustration, resulting from conflicts between the disulfide-constrained reduction of mobility and the desire to fulfill other favorable contacts.

Dynamic Disorder, Strain, and Sublimation of Crystalline Caged Hydrocarbons from First Principles

Dynamic Disorder, Strain, and Sublimation of Crystalline Caged Hydrocarbons from First Principles

Dynamic Regulation of Order Lipid Meso-domains in the Capillary Endothelial Cell Membrane

The structure and function of ion channels are sensitive to direct interactions with lipids of the membrane and to the biophysical properties of the membrane microenvironment, such that membrane fluidity, lateral pressure profile, and thickness can modulate the channels. Cholesterol plays a significant role in regulating membrane fluidity and is capable of phase separation where cholesterol will spontaneously separate into its own domain, which is partially responsible for developing two distinct domains within the membrane. These ordered domains are regions of high cholesterol and low fluidity, and the disordered domains are regions of low cholesterol and high fluidity. Here we examine and provide evidence of the presence of ordered cholesterol membrane domains in capillary endothelial cells. We will test the hypothesis that capillary endothelial cell ordered domains function as a signaling hub for different phospholipids regulating ion channel function. Using the isolated retinal vasculature, confocal microscopy, and fluorescent Bodipy-cholesterol, a marker of ordered lipid domains, we observed large regions approximately 2.3± 0.9 μm long of cholesterol ordered meso-domains within capillary endothelial cells and not the feeding arteriole. To determine the dynamic nature of these meso-domains, we used membrane-disordering drugs to disrupt the organization of membrane lipids. The ordered meso-domains display dynamic membrane disordering by ethanol and can re-cluster into the large ordered meso-domains. In addition, we observed that the critical signaling phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2) co-localized with the ordered meso-domains. To determine the cooperativity between these lipid molecules, we examined the effects of ethanol-dependent disordering of cholesterol on the membrane localization of PIP2. In addition, we examined the effects of PIP2 depletion with the G-protein couple receptor agonist, U46619, on the disordered state of the cholesterol meso-domains. These data suggest that ordered meso-domains might play a role as a signaling hub affecting the membrane fluidity and bioavailability of signaling lipids modulating ion channel function in capillary endothelial cell. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

High uric acid aggravates apoptosis of lung epithelial cells induced by cigarette smoke extract through downregulating PRDX2 in chronic obstructive pulmonary disease.

Cigarette smoke exposure is the major cause of chronic obstructive pulmonary disease (COPD). Cigarette smoke heightens the elevation of reactive oxygen species (ROS) and thus leads to apoptosis. Hyperuricemia has been considered as a risk factor for COPD. However, the underlying mechanism for this aggravating effect remains unclear. The current study sought to examine the role of high uric acid (HUA) in COPD using cigarette smoke extract (CSE) exposed murine lung epithelial (MLE-12) cells. Our data showed that CSE induced the increase of ROS, mitochondrial dynamics disorder, and apoptosis, while HUA treatment aggravated the effects of CSE. Further studies suggested that HUA decreased the expression of antioxidant enzyme-peroxiredoxin-2 (PRDX2). Overexpression of PRDX2 inhibited excessive ROS generation, mitochondrial dynamics disorder, and apoptosis induced by HUA. Knockdown of PRDX2 by small interfering RNA (siRNA) promoted ROS generation, mitochondrial dynamics disorder, and apoptosis in MLE-12 cells treated with HUA. However, antioxidant N-acetylcysteine (NAC) reversed the effects of PRDX2-siRNA on MLE-12 cells. In conclusion, HUA aggravated CSE-induced cellular ROS levels and led to ROS-dependent mitochondrial dynamics disorder and apoptosis in MLE-12 cells through downregulating PRDX2.

Mechanism for the Combined Li–Na Ionic Conductivity in Sugilite (Fe2Na2K[Li3Si12O30])-Type Compounds

This study explains the ionic conductivity in the mineral sugilite (idealized formula: Fe2Na2K[Li3Si12O30]) by resolving the dynamic disorder of both Li and Na cations using synchrotron X-ray single-crystal diffraction from 298 K to 1023 K. Non-zero anharmonic atomic displacement parameters at Na and Li sites at 1023 K adumbrated long-range charge transport routes for Li and Na cations commonly parallel to the (a–b) plane. Temperature-enhanced diffuse residuals in Fourier maps could unambiguously localize two interstitial sites suitable for Li, as well as three for Na. Each two-dimensional (2D) network of Li and Na interstitials was formed parallel to each other, providing Li and Na hopping pathways. The higher concentration of Na cations hopping in short distances of 2.0962(4)–2.3015(5) Å could be the main reason for the higher bulk conductivity values evaluated by impedance spectra of sugilite in comparison to those of its structural relatives with low Na contents, e.g., the mineral sogdianite ((Zr,Al,Fe)2Na0.36K[Li3Si12O30]). Bond valence sum landscape maps supported the critical role of dynamic disorder of Na+ over densely packed 2D interstitial networks for combined ionic conductivity along with mobile Li+ in sugilite-type compounds.

The Complex Interplay between Imbalanced Mitochondrial Dynamics and Metabolic Disorders in Type 2 Diabetes.

Type 2 diabetes mellitus (T2DM) is a global burden, with an increasing number of people affected and increasing treatment costs. The advances in research and guidelines improve the management of blood glucose and related diseases, but T2DM and its complications are still a big challenge in clinical practice. T2DM is a metabolic disorder in which insulin signaling is impaired from reaching its effectors. Mitochondria are the "powerhouses" that not only generate the energy as adenosine triphosphate (ATP) using pyruvate supplied from glucose, free fatty acid (FFA), and amino acids (AA) but also regulate multiple cellular processes such as calcium homeostasis, redox balance, and apoptosis. Mitochondrial dysfunction leads to various diseases, including cardiovascular diseases, metabolic disorders, and cancer. The mitochondria are highly dynamic in adjusting their functions according to cellular conditions. The shape, morphology, distribution, and number of mitochondria reflect their function through various processes, collectively known as mitochondrial dynamics, including mitochondrial fusion, fission, biogenesis, transport, and mitophagy. These processes determine the overall mitochondrial health and vitality. More evidence supports the idea that dysregulated mitochondrial dynamics play essential roles in the pathophysiology of insulin resistance, obesity, and T2DM, as well as imbalanced mitochondrial dynamics found in T2DM. This review updates and discusses mitochondrial dynamics and the complex interactions between it and metabolic disorders.

14, 15-EET alleviates neurological impairment through maintaining mitochondrial dynamics equilibrium via AMPK/SIRT1/FoxO1 signal pathways in mice with cerebral ischemia reperfusion.

To explore whether 14, 15-EET regulates mitochondrial dynamics to exert neuroprotective effects after cerebral ischemia-reperfusion and its underlying mechanisms. The mouse middle cerebral artery occlusion reperfusion model was used to observe brain infarct volume and neuronal apoptosis by TTC staining and Tunel assay, modified neurological severity score to detect neurological impairment, HE staining and Nissl staining to observe neuron damage, western blot and immunofluorescence methods to detect the expression of mitochondrial dynamics-related proteins, transmission electron microscopy, and Golgi-Cox staining to detect mitochondrial morphology and neuronal dendritic spines. 14, 15-EET reduced the neuronal apoptosis and cerebral infarction volume induced by middle cerebral artery occlusion reperfusion (MCAO/R), inhibited the degradation of dendritic spines, maintained the structural integrity of neurons, and alleviated neurological impairment. Cerebral ischemia-reperfusion induces mitochondrial dynamics disorders, upregulates the expression of the mitochondrial division protein Fis 1, and inhibits the expression of mitochondrial fusion proteins MFN1, MFN2, and OPA1, while 14, 15-EET treatment reverses this process. Mechanistic studies have shown that 14, 15-EET promotes the phosphorylation of AMPK, upregulates the expression of SIRT1 and phosphorylation of FoxO1, thereby inhibiting mitochondrial division and promoting mitochondrial fusion, preserving mitochondrial dynamics, maintaining neuronal morphological and structural integrity, and alleviating neurological impairment induced by middle cerebral artery occlusion reperfusion. Compound C treatment diminishes the neuroprotective effect of 14, 15-EET following MCAO/R in mice. This study elucidates the novel neuroprotective mechanism of 14, 15-EET, providing a novel approach for the development of drugs based on mitochondrial dynamics.

Critical and scaling behavior of delayed bifurcations in nonlinear systems with dynamic disorder

Critical and scaling behavior of delayed bifurcations in nonlinear systems with dynamic disorder

Cannabidiol Alleviates Perfluorooctanesulfonic Acid-Induced Cardiomyocyte Apoptosis by Maintaining Mitochondrial Dynamic Balance and Energy Metabolic Homeostasis.

Perfluorooctanesulfonic acid (PFOS), a fluorine-containing organic compound, can be widely detected in the environment and living organisms. Accumulating evidence has shown that PFOS breaks through different biological barriers resulting in cardiac toxicity, but the underlying molecular mechanisms remain unclear. Cannabidiol (CBD) is a nonpsychoactive cannabinoid without potential adverse cardiotoxicity and has antioxidant and anti-inflammatory properties that reduce multiorgan damage and dysfunction. For these reasons, the aim of this study was to research how PFOS caused heart injury and whether CBD could attenuate PFOS-induced heart injury. Mice were fed PFOS (5 mg/kg) and/or CBD (10 mg/kg) in vivo. In vitro, H9C2 cells were intervened with PFOS (200 μM) and/or CBD (10 μM). After PFOS exposure, oxidative stress levels and the mRNA and protein expression of apoptosis-related markers increased distinctly, accompanied by mitochondrial dynamic imbalance and energy metabolism disorders in mouse heart and H9C2 cells. Moreover, terminal deoxynucleotidyl transferase dUTP nick end labeling staining, acridine orange/ethidium bromide staining and Hoechst 33258 staining signaled that the number of apoptotic cells increased after exposure to PFOS. Noteworthy, CBD simultaneous treatment alleviated a series of damages caused by PFOS-mediated oxidative stress. Our results demonstrated that CBD could alleviate PFOS-induced mitochondrial dynamics imbalance and energy metabolism disorder causing cardiomyocyte apoptosis by improving the antioxidant capacity, suggesting that CBD may represent a novel cardioprotective strategy against PFOS-induced cardiotoxicity. Our findings facilitate the understanding of the cardiotoxic effects of PFOS and the important role of CBD in protecting cardiac health.

326 Sleep Stages Variation in Intracranial Pressure and Pulse Amplitude

INTRODUCTION: It is thought that CSF pulsatility has an important role in brain physiology during sleep. Yet few studies have looked into changes of ICP and pulsatility during sleep. METHODS: A single centre prospective cohort study. Patients undergoing 24 h ICP monitoring for suspected CSF dynamic disorders underwent concomitant polysomnography. Clinical and radiological presentation were derived from the patient’s records. Aggregate mean ICP and pulse amplitude (mPA) values were recorded for each sleep stage. Sleep staging was performed in conformity with the AASM guidelines. Within subject values were compared using repeated-measures, one-way ANOVA. Post-hoc paired t-tests were used to compare sleep stages between groups corrected for multiple comparisons (Benjamini-Hochberg method). RESULTS: A total of 12 patients (10 females, 2 males; mean age 40.8 years, SD+/- 12.9) with complete data were analysed. There were significant differences in mean ICP between sleep stages (F(3,33) = 10.7, p < 0.00001). Post-hoc paired t-tests revealed significant differences between rapid eye movement (REM; mean ICP 14.4 mmHg) and all other sleep stages (mean ICP/N1 = 12.0 mmHg, t = -3.6, p = 0.004; ICP/N2 = 11.8 mmHg, t = -4.3, p = 0.001; ICP/N3 = 12.3 mmHg, t = -3.5, p = 0.004). Significant differences were also found in mPA between sleep stages (F(3,33) = 5.7, p = 0.003) confirmed on post-hoc paired t-tests: REM (mean mPA 5.5 mmHg and all other sleep stages: mPA/N1 = 4.7 mmHg, t = -2.3, p = 0.04; mPA/N2 = 4.3 mmHg, t = -2.7, p = 0.02; mPA/N3 = 4.5 mmHg, t = -2.3, p = 0.04). CONCLUSIONS: REM is characterized by higher ICP and mPA values, result confirmed in near-normal patients included in this cohort.

Classification of perovskite structural types with dynamical octahedral tilting.

Perovskites ABX3 with delocalized positions of the X atoms represent a distinct class of dynamically distorted structures with peculiar structural relations and physical properties. The delocalization originates from atoms crossing shallow barriers of the potential energy surface. Quantum mechanically, they can be treated similar to light atoms in diffusive states. Many of these perovskite structures are widely used functional materials thanks to their particular physical properties, such as superconductivity, ferroelectricity and photo-activity. A number of these properties are related to static or dynamic motion of octahedral units. Yet, a full understanding of the relationships between perovskite crystal structure, chemical bonding and physical properties is currently missing. Several studies indicate the existence of dynamic disorder generated by anharmonic motion of octahedral units, e.g. in halide perovskite structures. To simplify structural analysis of such systems we derive a set of space groups for simple perovskites ABX3 with dynamical octahedral tilting. The derived space groups extend the well established space group tables for static tiltings by Glazer [Acta Cryst. B (1972). 28, 3384-3392], Aleksandrov [Ferroelectrics (1976). 24, 801-805] and Howard & Stokes [Acta Cryst. B (1998). 54, 782-789]. Ubiquity of dynamical tilting is demonstrated by an analysis of the structural data for perovskites reported in recent scientific publications and the signature of dynamic tilting in the corresponding structures is discussed, which can be summarized as follows: (a) volume increase upon a lowering of temperature, (b) apparent distortion of octahedra (where Jahn-Teller distortions can be ruled out), (c) mismatch between observed instantaneous symmetry and average symmetry, (d) deviation of the experimental space group from the theoretically predicted structures for static tilting, (e) inconsistency of lattice parameters with those suggested by the theory of static tilts, and (f) large displacement parameters for atoms at the X and B sites. Finally, the possible influence of dynamic disorder on the physical properties of halide perovskites is discussed.

Lattice softness regulates recombination and lifetime of carrier in Germanium doped CsPbI2Br perovskite: First principles DFT and NAMD simulations

Perovskite materials are characterized by high concentration of intrinsic defects. These defects lead to non-radiative recombination of electron and hole pairs, which is one of the major factors leading to the poor performance of the optoelectronic devices fabricated from these materials. Using the first-principles method, we have demonstrated that energy loss due to non-radiative recombination is suppressed in defective CsPbI2Br (D-CsPbI2Br) with the doping of Germanium (Ge) in CsGexPb1-xI2Br (x ​= ​0.15). Bromine vacancy (VBr) in CsPbI2Br introduces localized states as seen in the PDOS, however, doping of Ge eliminates these states. Using nonadiabatic molecular dynamics (NA-MD) and time-domain density functional theory, we show that the lifetime of the charge carriers is extended in Ge-doped CsPbI2Br (D-GeCsPbI2Br) by a factor of 3 and the dephasing time shortens to 6.2 ns. The electron localization function (ELF) plots of bulk CsPbI2Br (B–CsPbI2Br) show that charge localization increases around the Ge atom and it decreases the interaction between Pb atoms. In D-CsPbI2Br, phonons from a wide range of frequencies participate in scattering, and weak non-adiabatic (NA) coupling between electron and phonon in association with phonon modes in the low-frequency spectrum is responsible for extending the lifetime of charge carriers. Strong dynamic disorder in molecular dynamics (MD) simulations points to softening of lattice in D-GeCsPbI2Br. The increase in lattice softness of the Ge-doped is confirmed by the reduced value of bulk modulus (13.2 ​GPa) in D-GeCsPbI2Br as compared to the value in D-CsPbI2Br (13.6 ​GPa). Computing inverse participation ratio (IPR) gives the degree of localization of charge in the valence-band maximum (VBM) and conduction-band minimum (CBM). We have investigated the behavior of IPR and carrier lifetime with temperature, and based on these results, we found that lattice softness and a lifetime of charge carriers increase in D-GeCsPbI2Br.

Pathogenesis, clinical manifestations, diagnosis, and treatment progress of achalasia of cardia.

Achalasia cardia, type of esophageal dynamic disorder, is a relatively rare primary motor esophageal disease characterized by the functional loss of plexus ganglion cells in the distal esophagus and lower esophageal sphincter. Loss of function of the distal and lower esophageal sphincter ganglion cells is the main cause of achalasia cardia, and is more likely to occur in the elderly. Histological changes in the esophageal mucosa are considered pathogenic; however, studies have found that inflammation and genetic changes at the molecular level may also cause achalasia cardia, resulting in dysphagia, reflux, aspiration, retrosternal pain, and weight loss. Currently, the treatment options for achalasia focus on reducing the resting pressure of the lower esophageal sphincter, helping to empty the esophagus and relieve symptoms. Treatment measures include botulinum toxin injection, inflatable dilation, stent insertion, and surgical myotomy (open or laparoscopic). Surgical procedures are often subject to controversy owing to concerns about safety and effectiveness, particularly in older patients. Herein, we review clinical epidemiological and experimental data to determine the prevalence, pathogenesis, clinical presentation, diagnostic criteria, and treatment options for achalasia to support its clinical management.

Anatomic and Magnetic Resonance Imaging-Based Correction of Upper-Eyelid Depression and Blepharoptosis in Senile Patients.

In senile patients with sunken superior sulcus, involutional ptosis, and higher eyelid crease, a single operation to correct depression or ptosis cannot achieve good results. We demonstrated the anatomy of periorbital septum fibers, which may contribute to the levator muscle's volume depletion and dynamic power transmission disorder, and described a procedure for correcting upper-eyelid depression and blepharoptosis in senile patients. The fibrous webs in these patients connected the posterior aspect of the orbicularis and the orbital septum and extended to the orbital fat and levator aponeurosis. These fibers were dissected to release the periorbital septal fibers, and the orbital septal fat flap was transferred to the depressed region. Advancement or plication of the levator aponeurosis was performed in patients with uncorrected blepharoptosis after the procedures described above. The technique was applied to 13 Chinese patients (25 eyes) between May 2021 and April 2022. Postoperative magnetic resonance imaging revealed that the preaponeurotic fat was displaced forward and down to the upper margin of the tarsus, and the curvature of the upper-eyelid depression was significantly improved. Moreover, the superior sulcus deformity improved, the ptosis was corrected, and the uppermost crease decreased in all patients. No recurrence of ptosis or abnormal adhesion was observed. We believe this is the first study using magnetic resonance imaging to evaluate eyelid anatomy and the effects of surgery in this patient group. Releasing periorbital septum fibers is crucial for correcting a portion of the sunken eyelid and ptosis in Asians.

Dynamic Disorder Drives Exciton Dynamics in Diketopyrrolopyrrole–Thiophene-Containing Molecular Crystals

There is a growing interest in controllable molecular materials for potential nanophotonic and quantum information applications where excitons move beyond the incoherent transport regime. Thus, the ability to identify the key parameters that correlate with the efficiency of the transport of the excitation energy is highly desirable. In this work, we investigate the effects of the dynamic disorder on the transport of the exciton in molecular crystals of several mono- and dialkylated 1,4-diketo-3,6-dithiophenylpyrrolo[3-4-c]pyrrole derivatives. These systems exhibit great potential for photovoltaic applications due to their broad optical absorption and efficient charge transport. The exciton dynamics are studied using a model Hamiltonian, in which the thermal fluctuations of the excitonic coupling (nonlocal electron–phonon coupling), as well as the local exciton–phonon couplings, have been appropriately taken into account. The computed reorganization energies for the most feasible transport pathway (π–π stacking) for the excitons in UBEQUQ and UBEQOK molecular crystals are 0.366 and 0.357 eV, respectively. These values are comparable with the magnitude of the average excitonic coupling ⟨J⟩ (≈ 0.1 eV) for these two molecular crystals. In this instance, the local exciton–phonon coupling is not large enough to form a small exciton-polaron. In addition, substantial coherences are observed on a time scale of less than 100 fs, which indicates that the dynamic disorder is sufficient to overcome quantum dephasing and help drive exciton transport in this class of organic semiconductors. On the other hand, the diffusion of the excitons reduces significantly when the thermal fluctuations of the excitonic coupling are omitted. Thus, dynamic disorder plays a vital role in the transport of the exciton, and the ability to control this inherent property in molecular aggregates will provide valuable tools for the design and development of efficient organic semiconductors.

The Effect of the Combination of Tera Gymnastics and Square Stepping Exercises on the Level of the Elderly's Dynamic Balance

With increasing age, there is a decrease in the degenerative body, such as a decrease in musculoskeletal, neuromuscular, and cardiovascular functions, as well as a reduced ability to perform daily activities. One of the declines in musculoskeletal function is a decrease in muscle function, which causes muscle fibres to shrink, causing a decrease in strength, muscle mass, and bone mass. This causes dynamic balance disorders in the elderly. To improve and maintain dynamic balance, a combination of Tera Gymnastics and Square Stepping exercises are given to the elderly. This study aimed to determine whether there is an effect of the combination of Tera Gymnastics and Square Stepping Exercises on the level of the dynamic balance of the elderly in Sasana Malang. The research design was pre-experimental, namely the One Group Pre-Test and Post-Test Design. The study was focused on 35 elderly people for four weeks. The research instrument used was the Timed Up and Go Test. Shapiro Wilk Test data was normal, Pre-Test was 14.2317, and Post-Test was 11.9480. Paired Sample T Test significance was 0.000, H0 was rejected and H1 was accepted. It was discovered that a combination of Tera Gymnastics and Square Stepping exercises for 4 weeks increases the dynamic balance of the elderly in Sasana Malang.
 Keywords: tera, square stepping exercise, dynamic balance

Machine learning based charge mobility prediction for organic semiconductors.

Transfer integral is a crucial parameter that determines the charge mobility of organic semiconductors, and it is very sensitive to molecular packing motifs. The quantum chemical calculation of transfer integrals for all the molecular pairs in organic materials is usually an unaffordable task; fortunately, it can be accelerated by the data-driven machine learning method now. In this work, we develop machine learning models based on artificial neutral networks to predict transfer integrals accurately and efficiently for four typical organic semiconductor molecules: quadruple thiophene (QT), pentacene, rubrene, and dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT). We test various forms of features and labels and evaluate the accuracy of different models. With the implementation of a data augmentation scheme, we have achieved a very high accuracy with the determination coefficient of 0.97 and mean absolute error of 4.5meV for QT, and similar accuracy for the other three molecules. We apply these models to studying charge transport in organic crystals with dynamic disorders at 300K and obtain the charge mobility and anisotropy in perfect agreement with the brutal force quantum chemical calculation. If more molecular packings representing the amorphous phase of organic solids are supplemented to the dataset, the current models can be refined to study charge transport in organic thin films with polymorphs and static disorders.

Deep mining of the protein energy landscape

For over half a century, it has been known that protein molecules naturally undergo extensive structural fluctuations, and that these internal motions are intimately related to their functional properties. The energy landscape view has provided a powerful framework for describing the various physical states that proteins visit during their lifetimes. This Perspective focuses on the commonly neglected and often disparaged axis of the protein energy landscape: entropy. Initially seen largely as a barrier to functionally relevant states of protein molecules, it has recently become clear that proteins retain considerable conformational entropy in the "native" state, and that this entropy can and often does contribute significantly to the free energy of fundamental protein properties, processes, and functions. NMR spectroscopy, molecular dynamics simulations, and emerging crystallographic views have matured in parallel to illuminate dynamic disorder of the "ground state" of proteins and their importance in not only transiting between biologically interesting structures but also greatly influencing their stability, cooperativity, and contribution to critical properties such as allostery.

Ultra-long quantum walks via spin–orbit photonics

The possibility of fine-tuning the couplings between optical modes is a key requirement in photonic circuits for quantum simulations. In these architectures, emulating the long-time evolution of particles across large lattices requires sophisticated setups that are often intrinsically lossy. Here we report ultra-long photonic quantum walks across several hundred optical modes, obtained by propagating a light beam through very few closely stacked liquid-crystal metasurfaces. By exploiting spin–orbit effects, these implement space-dependent polarization transformations that mix circularly polarized optical modes carrying quantized transverse momentum. As each metasurface implements long-range couplings between distant modes, by using only a few of them we simulate quantum walks up to 320 discrete steps without any optical amplification, far beyond state-of-the-art experiments. To showcase the potential of this method, we experimentally demonstrate that in the long time limit a quantum walk affected by dynamical disorder generates maximal entanglement between two system partitions. Our platform grants experimental access to large-scale unitary evolutions while keeping optical losses at a minimum, thereby paving the way to massive multi-photon multi-mode quantum simulations.

Compression algorithms reveal memory effects and static disorder in single-molecule trajectories

Information-theory-based analysis of single-molecule time series, inspired by Shannon's studies of the information content of printed English, can differentiate between Markov (memoryless) and non-Markov single-molecule signals and between static and dynamic disorder.