Physical realization of a quantum spin liquid based on a novel frustration mechanism

Unlike conventional magnets where the magnetic moments are partially or completely static in the ground state, in a quantum spin liquid they remain in collective motion down to the lowest temperatures. The importance of this state is that it is coherent and highly entangled without breaking local symmetries. Such phenomena is usually sought in simple lattices where antiferromagnetic interactions and/or anisotropies that favor specific alignments of the magnetic moments are "frustrated" by lattice geometries incompatible with such order e.g. triangular structures. Despite an extensive search among such compounds, experimental realizations remain very few. Here we describe the investigation of a novel, unexplored magnetic system consisting of strong ferromagnetic and weaker antiferromagnetic isotropic interactions as realized by the compound Ca$_{10}$Cr$_7$O$_{28}$. Despite its exotic structure we show both experimentally and theoretically that it displays all the features expected of a quantum spin liquid including coherent spin dynamics in the ground state and the complete absence of static magnetism.Comment: Modified version accepted in Nature Physic

Biomass waste carbon materials for post-combustion CO2 capture

Low-carbon energy systems based on carbon capture and storage (CCS) have become of great interest due to the imperative necessity of mitigating the carbon footprint derived from the currently fossil fuels-based energy technologies. In this sense, post-combustion CO2 adsorption over porous solids results particularly attractive from several viewpoints. In a green context, the use of carbon-based materials as adsorbents would entail important economic and environmental profits, such as the valorization of different types of biomass and lignocellulosic waste. In this work, six carbon materials were prepared from four types of low cost biomass residues. Electrospun carbon fibers, FCL, and a char, GCL, were obtained from Alcell® lignin. Two activated carbons, GAS and GAWBa, resulted from physical activation of olive stones and plywood waste, respectively. Finally, another activated carbon, GAL, and an activated carbon cloth, CAD, were synthesized by chemical activation of lignin and a denim cloth. These materials were evaluated as potential adsorbents for CO2 capture under post-combustion conditions by means of equilibrium and dynamic experiments (fixed-bed system). Moreover, the regeneration capacity of the samples was also studied. At 101.3 kPa, the samples displayed CO2 capacities between 2.0 and 3.1 mmol/g. Meaningfully, the uptake values, at typical CO2 pressures in post-combustion applications (c.a. 15 kPa), remain in the range of 0.7 to 1.2 mmol/g, which are comparable to those of other complex and appealing materials. Additionally, a thorough characterization of the porous structure of the different adsorbents provided new insights into the influence of the pore size distribution on the CO2 capture capacity. CO2 retention capacities correlate well with the narrow micropore volume derived from the CO2 adsorption data at 0 ºC, VDRCO2, at 101.3 kPa (Figure 2). In contrast, at 15 kPa, analysis of the cumulative pore volumes of the samples pointed out that only pores of sizes below 0.7 nm are relevant for adsorption. Under dynamic conditions, the studied materials also showed remarkable adsorptive behaviors. For instance, the lignin-derived carbon fiber (FCL) exhibited a capacity value higher than 1.3 mmol/g.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Sacral agenesis: a pilot whole exome sequencing and copy number study

Background: Caudal regression syndrome (CRS) or sacral agenesis is a rare congenital disorder characterized by a constellation of congenital caudal anomalies affecting the caudal spine and spinal cord, the hindgut, the urogenital system, and the lower limbs. CRS is a complex condition, attributed to an abnormal development of the caudal mesoderm, likely caused by the effect of interacting genetic and environmental factors. A well-known risk factor is maternal type 1 diabetes. Method: Whole exome sequencing and copy number variation (CNV) analyses were conducted on 4 Caucasian trios to identify de novo and inherited rare mutations. Results: In this pilot study, exome sequencing and copy number variation (CNV) analyses implicate a number of candidate genes, including SPTBN5, MORN1, ZNF330, CLTCL1 and PDZD2. De novo mutations were found in SPTBN5, MORN1 and ZNF330 and inherited predicted damaging mutations in PDZD2 (homozygous) and CLTCL1 (compound heterozygous). Importantly, predicted damaging mutations in PTEN (heterozygous), in its direct regulator GLTSCR2 (compound heterozygous) and in VANGL1 (heterozygous) were identified. These genes had previously been linked with the CRS phenotype. Two CNV deletions, one de novo (chr3q13.13) and one homozygous (chr8p23.2), were detected in one of our CRS patients. These deletions overlapped with CNVs previously reported in patients with similar phenotype. Conclusion: Despite the genetic diversity and the complexity of the phenotype, this pilot study identified genetic features common across CRS patients

Novel ZNF414 activity characterized by integrative analysis of ChIP-exo, ATAC-seq and RNA-seq data

Transcription factor binding to DNA is a central mechanism regulating gene expression. Thus, thorough characterization of this process is essential for understanding cellular biology in both health and disease. We combined data from three sequencing-based methods to unravel the DNA binding function of the novel ZNF414 protein in cells representing two tumor types. ChIP-exo served to map protein binding sites, ATAC-seq allowed identification of open chromatin, and RNA-seq examined the transcriptome. We show that ZNF414 is a DNAbinding protein that both induces and represses gene expression. This transcriptional response has an impact on cellular processes related to proliferation and other malignancy-associated functions, such as cell migration and DNA repair. Approximately 20% of the differentially expressed genes harbored ZNF414 binding sites in their promoters in accessible chromatin, likely representing direct targets of ZNF414. De novo motif discovery revealed several putative ZNF414 binding sequences, one of which was validated using EMSA. In conclusion, this study illustrates a highly efficient integrative approach for the characterization of the DNA binding and transcriptional activity of transcription factors.Peer reviewe

Eukaryotic elongation factor 2 controls TNF-alpha translation in LPS-induced hepatitis

Bacterial LPS (endotoxin) has been implicated in the pathogenesis of acute liver disease through its induction of the proinflammatory cytokine TNF-alpha. TNF-alpha is a key determinant of the outcome in a well-established mouse model of acute liver failure during septic shock. One possible mechanism for regulating TNF-alpha expression is through the control of protein elongation during translation, which would allow rapid cell adaptation to physiological changes. However, the regulation of translational elongation is poorly understood. We found that expression of p38gamma/delta MAPK proteins is required for the elongation of nascent TNF-alpha protein in macrophages. The MKK3/6-p38gamma/delta pathway mediated an inhibitory phosphorylation of eukaryotic elongation factor 2 (eEF2) kinase, which in turn promoted eEF2 activation (dephosphorylation) and subsequent TNF-alpha elongation. These results identify a new signaling pathway that regulates TNF-alpha production in LPS-induced liver damage and suggest potential cell-specific therapeutic targets for liver diseases in which TNF-alpha production is involved

Umbilical Cord Pericytes Provide a Viable Alternative to Mesenchymal Stem Cells for Neonatal Vascular Engineering

Reconstructive surgery of congenital heart disease (CHD) remains inadequate due to the inability of prosthetic grafts to match the somatic growth of pediatric patients. Functionalization of grafts with mesenchymal stem cells (MSCs) may provide a solution. However, MSCs represent a heterogeneous population characterized by wide diversity across different tissue sources. Here we investigated the suitability of umbilical cord pericytes (UCPs) in neonatal vascular engineering. Explant outgrowth followed by immunomagnetic sorting was used to isolate neural/glial antigen 2 (NG2)+/CD31- UCPs. Expanded NG2 UCPs showed consistent antigenic phenotype, including expression of mesenchymal and stemness markers, and high proliferation rate. They could be induced to a vascular smooth muscle cell-like phenotype after exposure to differentiation medium, as evidenced by the expression of transgelin and smooth muscle myosin heavy chain. Analysis of cell monolayers and conditioned medium revealed production of extracellular matrix proteins and the secretion of major angiocrine factors, which conferred UCPs with ability to promote endothelial cell migration and tube formation. Decellularized swine-derived grafts were functionalized using UCPs and cultured under static and dynamic flow conditions. UCPs were observed to integrate into the outer layer of the graft and modify the extracellular environment, resulting in improved elasticity and rupture strain in comparison with acellular grafts. These findings demonstrate that a homogeneous pericyte-like population can be efficiently isolated and expanded from human cords and integrated in acellular grafts currently used for repair of CHD. Functional assays suggest that NG2 UCPs may represent a viable option for neonatal tissue engineering applications.This study was supported by Heart Research UK Ph.D. studentship Umbilical cord pericyte-engineered grafts for correction of congenital heart defects (RG2656/17/20) awarded to PM. In addition, this study was supported by the National Institute for Health Research (NIHR) Biomedical Research Centre at University Hospitals Bristol and Weston NHS Foundation Trust and the University of Bristol.S

How stable are visions for protected area management? Stakeholder perspectives before and during a pandemic

Envisioning processes enable protected area managers to chart a course for future management to reach desired goals, but unexpected changes that could affect future visions are not usually considered. The global COVID-19 pandemic provided an opportunity to explore changes in stakeholder visions, the values that underpin the visions, and their perceptions of landscape changes and the underlying drivers (e.g. climate change, mass tourism and demographic trends). Through a mixed-methods approach in this post-evaluation study, we gathered comparative data on these issues from stakeholders in the Sierra de Guadarrama National Park, Spain, between July 2019 (pre-pandemic) and October 2020 (mid-pandemic). Our qualitative analysis demonstrates that pre-pandemic, differences in visions for protected area management were largely spurred by different perceptions of drivers of change, rather than differences in values or perceived landscape changes, which were similar across different vision themes. One year later, in the midst of the COVID-19 pandemic, the majority of stakeholders reported that their values, visions and perceptions of drivers did not change despite this large-scale disturbance. Of the 20%-30% of stakeholders that did report changes, visions generally shifted towards greater prioritization of biodiversity and nature conservation as a result of heightened perceptions of the impacts of drivers of change associated with an increase in the numbers of park visitors. These drivers included mass tourism, mountain recreation, lack of environmental awareness, and change in values and traditions. Our findings reinforce the importance of adaptive and inclusive management of protected areas, including enhancing transparency and communications regarding factors driving change in the landscape, and integration of local and traditional knowledge and stakeholder perceptions of changes and drivers. Furthermore, management plans integrating stakeholder values have the potential to stay relevant even in the face of wildcard events such as a pandemic. To enhance the relevancy of visions and scenarios in conservation and land-use planning, scenario planning methodologies should more strongly consider different potential disturbances and how drivers of change in the near and far future can be affected by wildcard events such as a pandemic. A free Plain Language Summary can be found within the Supporting Information of this article.Peer reviewe

Reliable resolution of ambiguous hepatitis C virus genotype 1 results with the Abbott HCV Genotype Plus RUO assay

Accurate subtyping of hepatitis C virus genotype 1 (HCV-1) remains clinically and epidemiologically relevant. The Abbott HCV Genotype Plus RUO (GT Plus) assay, targeting the core region, was evaluated as a reflex test to resolve ambiguous HCV-1 results in a challenging sample collection. 198 HCV-1 specimens were analysed with GT Plus (38 specimens with and 160 without subtype assigned by the Abbott RealTime Genotype II (GT II) assay targeting the 5'NC and NS5B regions). Sanger sequencing of the core and/or NS5B regions were performed in 127 specimens without subtype assignment by GT II, with "not detected" results by GT Plus, or with mixed genotypes/subtypes. The remaining GT Plus results were compared to LiPA 2.0 (n = 45) or just to GT II results if concordant (n = 26). GT Plus successfully assigned the subtype in 142/160 (88.8%) samples. "Not detected" results indicated other HCV-1 subtypes/genotypes or mismatches in the core region in subtype 1b. The subtyping concordance between GT Plus and either sequencing or LiPA was 98.6% (140/142). Therefore, combined use of GT II and GT Plus assays represents a reliable and simple approach which considerably reduced the number of ambiguous HCV-1 results and enabled a successful subtyping of 98.9% of all HCV-1 samples