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IntroductionThe development of de novo anti-HLA donor specific antibodies (DSAs) is associated with poor outcomes in kidney transplant recipients. It is surmised that an interaction between DSAs and the graft endothelium cause tissue injury, however, the exact underlying pathomechanism and optimal management of patients with DSAs remain undetermined.AimsWe hypothesized that in kidney transplant recipients the presence of DSAs induce hemostasis alterations, including hypercoagulability, as assessed by the thrombin generation assay (TGA). Patients and methods. In this observational cohort study, 27 kidney transplant recipients with DSAs (DSA+ group) and 16 without DSAs (DSA– group) were enrolled. Venous blood samples were obtained, and besides routine laboratory tests, von Willebrand factor antigen (VWF), FVIII activity, soluble E selectin (sEsel), soluble P selectin (sPsel), TGA, clot lysis assay (CLA), complement levels (C3, C4) were measured. To correlate results with potential changes in DSA status over time, patients were followed and reassessed 6 ± 1.5 months later.ResultsVWF and sPsel did not differ between groups, but both parameters were increased in the majority of patients. Endogenous thrombin potential (ETP) was significantly higher in the DSA+ group as compared to DSA– patients (median:1666; IQR:1438-2012 vs. 1230; IQR:1097-1659 nM*min, p=0.0019). Follow-up measurements indicated that the observed hemostasis alterations were not transient. CLA parameters, C3 and C4 did not differ between DSA+ and DSA– groups. The extent of anti-HLA II DSA positivity correlated positively with ETP, while tacrolimus levels negatively correlated with ETP and VWF/FVIII levels.ConclusionsIn patients with anti-HLA class II DSAs, thrombin generation was significantly increased as compared to DSA– kidney transplant recipients, suggesting that the presence of antibodies is associated with hypercoagulability. Tacrolimus levels were negatively associated with TGA parameters. Hypercoagulability, associated with the presence of DSAs, may potentially contribute to the pathomechanism of antibody-mediated graft injury, warranting future prospective studies.

Abstract Point defect quantum bits in semiconductors have the potential to revolutionize sensing at atomic scales. Currently, vacancy-related defects are at the forefront of high spatial resolution and low-dimensional sensing. On the other hand, it is expected that impurity-related defect structures may give rise to new features that could further advance quantum sensing in low dimensions. Here, we study the symmetric carbon tetramer clusters in hexagonal boron nitride and propose them as spin qubits for sensing. We utilize periodic-DFT and quantum chemistry approaches to reliably and accurately predict the electronic, optical, and spin properties of the studied defect. We show that the nitrogen-centered symmetric carbon tetramer gives rise to spin state-dependent optical signals with strain-sensitive intersystem crossing rates. Furthermore, the weak hyperfine coupling of the defect to their spin environments results in a reduced electron spin resonance linewidth that can enhance sensitivity.

Stoichiometric carbon monoxide insertion processes leading to metal-formyl complexes are scarce, even for transition metals. Here, light is shed on the underexplored chemistry of beryllium hydrides leading to a stable example of a main group metal-formyl complex.

Plastic transformations are critical to ongoing recycling and upcycling efforts, but the complexity of the reactions makes it difficult to understand the effect of individual factors on reaction rates and product distributions experimentally. In this work, we report on a multiscale simulation framework for studying polymer transformations that incorporates affordable high‐level coupled cluster calculations combined with benchmarked density functional theory calculations, detailed conformer search, and lattice‐based kinetic Monte Carlo simulations to provide the temporal and spatial evolution of the polymer during transformations. Our framework can match experimentally observed reaction times within an order of magnitude without any parameter estimation in base‐assisted dehydrochlorination of polyvinyl chloride. We determine that the E2 reaction mechanism dominates the reaction and demonstrate that different structural defects can inhibit or promote directional polyene growth as well as affect the structure of the dehydrochlorination product. [ABSTRACT FROM AUTHOR]

Introduction: The development of de novo anti-HLA donor specific antibodies (DSAs) is associated with poor outcomes in kidney transplant recipients. It is surmised that an interaction between DSAs and the graft endothelium cause tissue injury, however, the exact underlying pathomechanism and optimal management of patients with DSAs remain undetermined. Aims: We hypothesized that in kidney transplant recipients the presence of DSAs induce hemostasis alterations, including hypercoagulability, as assessed by the thrombin generation assay (TGA). Patients and methods. In this observational cohort study, 27 kidney transplant recipients with DSAs (DSA+ group) and 16 without DSAs (DSA– group) were enrolled. Venous blood samples were obtained, and besides routine laboratory tests, von Willebrand factor antigen (VWF), FVIII activity, soluble E selectin (sEsel), soluble P selectin (sPsel), TGA, clot lysis assay (CLA), complement levels (C3, C4) were measured. To correlate results with potential changes in DSA status over time, patients were followed and reassessed 6 ± 1.5 months later. Results: VWF and sPsel did not differ between groups, but both parameters were increased in the majority of patients. Endogenous thrombin potential (ETP) was significantly higher in the DSA+ group as compared to DSA– patients (median:1666; IQR:1438-2012 vs. 1230; IQR:1097-1659 nM*min, p=0.0019). Follow-up measurements indicated that the observed hemostasis alterations were not transient. CLA parameters, C3 and C4 did not differ between DSA+ and DSA– groups. The extent of anti-HLA II DSA positivity correlated positively with ETP, while tacrolimus levels negatively correlated with ETP and VWF/FVIII levels. Conclusions: In patients with anti-HLA class II DSAs, thrombin generation was significantly increased as compared to DSA– kidney transplant recipients, suggesting that the presence of antibodies is associated with hypercoagulability. Tacrolimus levels were negatively associated with TGA parameters. Hypercoagulability, associated with the presence of DSAs, may potentially contribute to the pathomechanism of antibody-mediated graft injury, warranting future prospective studies. [ABSTRACT FROM AUTHOR]

Chloride leaching/removal is a fundamental reaction of polyvinyl chloride (PVC), pertinent to PVC recycling and environmental impacts. We show that quantum tunnelling (QT) drives >90% of chloride leaching from PVC to water at all environmentally relevant temperatures offering new insights into plastic degradation and transformation processes. [ABSTRACT FROM AUTHOR]

Existing metal-containing porous catalysts have inherent heterogeneity in metal species, rendering it difficult to compare reactivity across varied catalyst formulations without first developing active site quantification protocols. The supercages of faujasite zeolites (FAU) are large enough to confine metal phthalocyanines (MPCs), together serving as a well-defined active center for experimental and computational catalyst characterization. Deviations in zeolite synthesis conditions from prior literature were required to obtain phase-pure FAU. Metal perchloro-, perfluoro-, and perhydrogenated phthalocyanines (MPCCl16, MPCF16, and MPC; M = Cr, Mn, Fe, Co, Ni, Cu, and Zn) were encapsulated into FAU zeolites via hydrothermal synthesis (MPC@FAU) and deposited onto the external surfaces by postsynthetic deposition (MPC/FAU). These MPC@FAU catalysts were tested as catalysts for CO oxidation with dioxygen at 298 K and their reactivity compared to that of silica-supported PdAu nanoparticles and cobalt–nitrogen-doped carbon (Co–N–C). Initial CO2 site time yields were greater than the analogous metal-ion-exchanged zeolites (by ∼50×). However, this initial activity decreased with time on stream for all MPC samples tested, and the cause of this deactivation is explored herein. Stable CO2 formation rates with time on stream observed over PdAu/SiO2 and Co–N–C suggest that deactivation observed over MPC@FAU samples is distinct and not an artifact of the experimental apparatus. Density functional theory calculations suggest an O2-activation mechanism, aided by the coadsorption of CO on the pyrrole N of the MPC and an axial ligand that can provide additional electron density to reduce the barrier for O2 bond breaking; this reaction mechanism is distinct from that over structurally similar metal-nitrogen-doped carbons. Nevertheless, the reactivity of MPC@FAU catalysts for gas-phase CO oxidation with dioxygen at ambient temperature indicates that they may share similar functionality to metal–nitrogen-doped carbons and have the potential to serve as model catalysts for gas-phase chemistries. [ABSTRACT FROM AUTHOR]

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Abstract Background Parkinsonism is a complex multifactorial neurodegenerative disorder, in which genetic and environmental risk factors may both play a role. Among environmental risk factors cocaine was earlier ambiguously linked to Parkinsonism. Former single case reports described Parkinsonism in chronic cocaine users, but an epidemiological study did not confirm an increased risk of Parkinson’s disease. Here we report a patient, who developed Parkinsonism in young age after chronic cocaine use, in whom a homozygous LRRK2 risk variant was also detected. Case presentation The patient was investigated because of hand tremor, which started after a 1.5-year period of cocaine abuse. Neurological examination suggested Parkinsonism, and asymmetrical pathology was confirmed by the dopamine transporter imaging study. The genetic investigations revealed a homozygous risk allele in the LRRK2 gene. After a period of cocaine abstinence, the patient’s symptoms spontaneously regressed, and the dopamine transporter imaging also returned to near-normal. Conclusions This case report suggests that cocaine abuse indeed might be linked to secondary Parkinsonism and serves as an example of a potential gene-environmental interaction between the detected LRRK2 risk variant and cocaine abuse. The reversible nature of the DaTscan pathology is a unique feature of this case, and needs further evaluation, whether this is incidental or can be a feature of cocaine related Parkinsonism.

The phenomenon of laser-assisted alpha decay is studied within the framework of non-Hermitian quantum theory integrated with the (t, t ′)-formalism. The width and the lifetime of the alpha cluster of a specific isotope is extracted from the spectrum of the complex-scaled Hamiltonian operator of the nuclear system and estimated numerically. The laser-field-induced correction to the lifetime is computed by first-order (t, t ′)-perturbation calculation with regard to different polarization states and control parameters of the external laser field, adjusting appropriate intensity and photon energy pairs by examining the limit of the non-relativistic approximation of the problem. [ABSTRACT FROM AUTHOR]