An improved limit on the neutrinoless double-electron capture of 36Ar with GERDA

The GERmanium Detector Array (Gerda) experiment operated enriched high-purity germanium detectors in a liquid argon cryostat, which contains 0.33% of 36 Ar, a candidate isotope for the two-neutrino double-electron capture (2ν ECEC) and therefore for the neutrinoless double-electron capture (0ν ECEC). If detected, this process would give evidence of lepton number violation and the Majorana nature of neutrinos. In the radiative 0ν ECEC of 36 Ar, a monochromatic photon is emitted with an energy of 429.88 keV, which may be detected by the Gerda germanium detectors. We searched for the 36 Ar 0ν ECEC with Gerda data, with a total live time of 4.34 year (3.08 year accumulated during Gerda Phase II and 1.26 year during Gerda Phase I). No signal was found and a 90% CL lower limit on the half-life of this process was established T 1 / 2 > 1.5 · 10 22  year.

Supplementary Information

The online version contains supplementary material available at 10.1140/epjc/s10052-023-12280-6.

Dynamically Tunable Assemblies of Superparamagnetic Nanoparticles Stabilized with Liquid Crystal-like Ligands in Organic Thin Films

The process of arranging magnetic nanoparticles (MNPs) into long-range structures that can be dynamically and reversibly controlled is challenging, although interesting for emerging spintronic applications. Here, we report composites of MNPs in excess of LC-like ligands as promising materials for MNP-based technologies. The organic part ensures the assembly of MNP into long-range ordered phases as well as precise and temperature-reversible control over the arrangement. The dynamic changes are fully reversible, which we confirm using X-ray diffraction (XRD). This methodology allows for the precise control of the nanomaterial's structure in a thin film at different temperatures, translating to variable unit cell parameters. The composition of the materials (XPS, TGA), their structure (XRD), and magnetic properties (SQUID) were performed. Overall, this study confirms that LC-like materials provide the ability to dynamically control the magnetic nanoparticles in thin films, particularly the reversible control of their self-organization.

Final Results of GERDA on the Two-Neutrino Double-β Decay Half-Life of ^{76}Ge

We present the measurement of the two-neutrino double-β decay rate of ^{76}Ge performed with the GERDA Phase II experiment. With a subset of the entire GERDA exposure, 11.8 kg yr, the half-life of the process has been determined: T_{1/2}^{2ν}=(2.022±0.018_{stat}±0.038_{syst})×10^{21}  yr. This is the most precise determination of the ^{76}Ge two-neutrino double-β decay half-life and one of the most precise measurements of a double-β decay process. The relevant nuclear matrix element can be extracted: M_{eff}^{2ν}=(0.101±0.001).

Search for tri-nucleon decays of 76Ge in GERDA

We search for tri-nucleon decays of 76 Ge in the dataset from the GERmanium Detector Array (GERDA) experiment. Decays that populate excited levels of the daughter nucleus above the threshold for particle emission lead to disintegration and are not considered. The ppp-, ppn-, and pnn-decays lead to 73 Cu, 73 Zn, and 73 Ga nuclei, respectively. These nuclei are unstable and eventually proceed by the beta decay of 73 Ga to 73 Ge (stable). We search for the 73 Ga decay exploiting the fact that it dominantly populates the 66.7 keV 73 m Ga state with half-life of 0.5 s. The nnn-decays of 76 Ge that proceed via 73 m Ge are also included in our analysis. We find no signal candidate and place a limit on the sum of the decay widths of the inclusive tri-nucleon decays that corresponds to a lower lifetime limit of 1.2× 1026  yr  (90% credible interval). This result improves previous limits for tri-nucleon decays by one to three orders of magnitude.

Liquid argon light collection and veto modeling in GERDA Phase II

The ability to detect liquid argon scintillation light from within a densely packed high-purity germanium detector array allowed the Gerda experiment to reach an exceptionally low background rate in the search for neutrinoless double beta decay of76 Ge. Proper modeling of the light propagation throughout the experimental setup, from any origin in the liquid argon volume to its eventual detection by the novel light read-out system, provides insight into the rejection capability and is a necessary ingredient to obtain robust background predictions. In this paper, we present a model of the Gerda liquid argon veto, as obtained by Monte Carlo simulations and constrained by calibration data, and highlight its application for background decomposition.

Improved Measurement of Solar Neutrinos from the Carbon-Nitrogen-Oxygen Cycle by Borexino and Its Implications for the Standard Solar Model

We present an improved measurement of the carbon-nitrogen-oxygen (CNO) solar neutrino interaction rate at Earth obtained with the complete Borexino Phase-III dataset. The measured rate, R_{CNO}=6.7_{-0.8}^{+2.0}  counts/(day×100  tonnes), allows us to exclude the absence of the CNO signal with about 7σ C.L. The correspondent CNO neutrino flux is 6.6_{-0.9}^{+2.0}×10^{8}  cm^{-2} s^{-1}, taking into account the neutrino flavor conversion. We use the new CNO measurement to evaluate the C and N abundances in the Sun with respect to the H abundance for the first time with solar neutrinos. Our result of N_{CN}=(5.78_{-1.00}^{+1.86})×10^{-4} displays a ∼2σ tension with the "low-metallicity" spectroscopic photospheric measurements. Furthermore, our result used together with the ^{7}Be and ^{8}B solar neutrino fluxes, also measured by Borexino, permits us to disfavor at 3.1σ C.L. the "low-metallicity" standard solar model B16-AGSS09met as an alternative to the "high-metallicity" standard solar model B16-GS98.

Heart failure and the risk of left atrial thrombus formation in patients with atrial fibrillation and atrial flutter: insights from the LATTEE registry

Background

The aim of the study was to evaluate the prevalence of left atrial thrombus (LAT) on transesophageal echocardiography (TEE) in patients with atrial fibrillation and atrial flutter (AF/AFl) with reference to the presence of heart failure (HF) and its subtypes.

Methods

The research is a substudy of multicenter, prospective, observational Left Atrial Thrombus on Transesopahgeal Echocardiography (LATTEE) registry, which comprised 3109 consecutive patients with AF/AFl undergoing TEE prior to direct current cardioversion or catheter ablation. TEE parameters, including presence of LAT, were compared between patients with and without HF, as well as different subtypes of HF, including HF with preserved (HFpEF), mid-range (HFmrEF) and reduced ejection fraction (HFrEF).

Results

HF was diagnosed in 1336 patients (43%). HF patients had higher prevalence of LAT than non-HF patients (12.8% vs. 4.4%, P<0.001). The rate of LAT increased with the more advanced type of systolic dysfunction (HFrEF vs. HFmrEF vs. HFpEF: 20.3% vs. 10.5% vs. 7.4%, P<0.001; Figure 1). Univariate analysis revealed that HFrEF (OR 4.13, 95% CI: 3.13–5.46) but not HFmrEF or HFpEF predicted the presence of LAT. Multivariable logistic regression indicated that left ventricular ejection fraction (unit OR=0.94 per 1%, 95% CI: 0.93–0.95) was an independent predictor of LAT formation. Receiver operator characteristic analysis showed LVEF ≤48% predicted presence of LAT (AUC=0.74, P<0.0001).

Conclusion

The diagnosis of HFrEF, but not HFpEF, confers a considerable risk of LAT presence despite widespread utilization of adequate anticoagulation in the assessed population. TEE should be considered in these patients prior to cardioversion or catheter ablation despite adequate oral anticoagulation.

Funding Acknowledgement

Type of funding sources: None.

Predicting the presence of left atrial appendage thrombus with clinical features and transthoracic measurements using machine learning

Background

Atrial fibrillation and flutter (AF/AFl) increase the risk of thromboembolic events by promoting clot formation in the left atrium (LA), which can be visualised using transoesophageal echocardiography (TEE). Current guidelines recommend initiation of oral anticoagulation (OAC) in patients with AF/AFl based solely on CHA2DS2VASc score (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, history of stroke or thromboembolism, vascular disease, age 65 to 74 years, female sex). Yet, some patients develop left LA thrombus (LAT) and experience thromboembolic events despite OAC.

Purpose

We sought to develop and externally validate a machine learning model for prediction of presence of LAT based on clinical, laboratory and transthoracic echocardiography (TTE) features.

Methods

We analyzed data from the multicenter, prospective LATTEE registry (Left Atrial Thrombus on Transesophageal Echocardiography) that included patients from 13 sites who underwent TEE before cardioversion or ablation between November 2018 and March 2021. We used XgBoost model to predict presence of LAT in TEE based on 29 clinical features, 10 biomarkers and 5 TTE measurements. We trained and tested the model internally using 10-fold hold-out cross validation and data from 12 sites (N=2489). We then tested the final model externally using data from the 13th site (that had recruited most patients, N=400). We compared the predictive performance with that of CHA2DS2VASc score using areas under receiver operating curve (AUC) and DeLong test.

Results

In the training and internal testing cohort the median age was 67 (Inter Quartile Range [IQR] 59, 74), 63% were male, 85% received OAC and LAT was found in 8.4%. Ablation was the indication for TEE in 43%, cardioversion in 57%. In internal, 10-fold hold-out cross validation, the model achieved AUC of 0.755 (95% confidence interval [CI]: 0.722, 0.788) while CHA2DS2VASc performed significantly worse with AUC of 0.638 (95% CI: 0.604, 0.673), P<0.0001 (Figure 1). Left ventricular ejection fraction, rhythm at the time of study (AF/AFl or sinus rhythm) and age received the highest feature importance ranking (Figure 2).

In the external testing cohort the median age was 67 (IQR 59, 74), 66% were male, 88% received OAC, ablation was the indication for TEE in 49% of cases and LAT was found in 6.8%. In this external cohort, our model achieved AUC of 0.815 (95% CI: 0.741, 0.889) while CHA2DS2VASc performed significantly worse with AUC of 0.684 (95% CI: 0.583, 0.785), P=0.028.

Conclusion

Machine learning based on readily available clinical data allows accurate prediction of the presence of LAT in patients with AF/AFl irrespective of OAC treatment. Such score could be used to identify patients who should undergo TEE before ablation or cardioversion. Subsequent studies to clinically evaluate such application of our model as well as how the model can predict future thromboembolic events are warranted.

Funding Acknowledgement

Type of funding sources: None.

Erratum: First Search for Bosonic Superweakly Interacting Massive Particles with Masses up to 1 MeV/c^{2} with GERDA [Phys. Rev. Lett. 125, 011801 (2020)]

This corrects the article DOI: 10.1103/PhysRevLett.125.011801.

Noncytotoxic zinc-doped nanohydroxyapatite-based bone scaffolds with strong bactericidal, bacteriostatic, and antibiofilm activity

Development of bone scaffolds that are nontoxic to eukaryotic cells, while revealing bactericidal activity still remains a huge challenge for the scientific community. It should be noted that only bacteriostatic (the ability of the biomaterial to inhibit the growth of bacteria) and bactericidal (the ability to kill >99.9 % bacteria) activities have clinical importance. Unfortunately, many material scientists are confused with the microbiological definition of antibacterial action and consider biomaterials causing reduction in colony-forming units (CFUs) by 50-80 % as promising antibacterial implants. The aim of this study was to synthesize three variants of Zn-doped hydroxyapatite (HA) nanopowder, which were characterized by different content of Zn²⁺ and served as a powder phase for the production of novel macroporous chitosan/agarose/nanoHA biomaterials with high antibacterial activity. Within this study, it was proven that the scaffold with a low zinc content (doping level 0.03 mol for 1 mol of HA; 0.2 wt%) revealed the gradual and slow release of the Zn²⁺ ions, preventing against accumulation of high and toxic concentration of therapeutic agents and providing prolonged antibacterial activity. Moreover, developed biomaterial was nontoxic to human osteoblasts and showed anti-biofilm properties, bactericidal activity (> 99.9 % of bacteria killed) against Staphylococcus epidermidis and Escherichia coli, significant antibacterial activity against Staphylococcus aureus (98.5 % of bacteria killed), and also bacteriostatic activity against Pseudomonas aeruginosa. Thus, the developed Zn-doped HA-based bone scaffold has excellent antibacterial properties without toxicity against eukaryotic cells, being a promising biomaterial for biomedical applications to repair bone defects and prevent post-surgery infections.

Biocompatible curdlan-based biomaterials loaded with gentamicin and Zn-doped nano-hydroxyapatite as promising dressing materials for the treatment of infected wounds and prevention of surgical site infections

A topical application of antibiotic-loaded wound dressings is recommended only for chronically infected wounds with poor vascularization. Thus, more often dressing materials loaded with antibacterial metal ions are produced. In turn, gentamicin sponges are commonly used to prevent surgical site infections. The aim of this study was to produce curdlan-based biomaterials enriched with gentamicin and zinc (Zn)-doped nano-hydroxyapatite to prevent wound and surgical site infections. Developed biomaterials were subjected to basic microstructural characterization, cytotoxicity test against human skin fibroblasts (BJ cell line), and comprehensive microbiological experiments using Staphylococcus aureus and Pseudomonas aeruginosa strains. To evaluate the in vivo healing capacity of the developed biomaterials, severely infected chronic wound in a veterinary patient was treated with the use of gentamicin-loaded dressing. Fabricated biomaterials were characterized by a highly porous microstructure with high plasma absorption capacity (approx. 7 mL/g for Zn-loaded biomaterial and 13 mL/g for gentamicin-enriched dressing) and optimal water vapor transmission rate (approx. 1700 g/m²/day). Due to the presence of bioceramics, material containing Zn showed slightly higher compressive strength (0.37 MPa) and Young's modulus (3.33 MPa) values compared to gentamicin-loaded biomaterial (0.12 MPa and 1.29 MPa, respectively). Gentamicin-enriched biomaterial showed burst release of the drug within the first 5 h, while, the zinc-loaded biomaterial exhibited a constant gradual release of the zinc ions. Conducted assays showed that developed biomaterials were non-toxic against human skin fibroblasts (cell viability in the range of 71-95 %) and revealed strong bactericidal activity (99.9 % reduction in the number of viable bacterial CFUs in direct contact test) against S. aureus. In the case of P. aeruginosa, only gentamicin-loaded biomaterial exhibited bactericidal effect. Additionally, biomaterials had the ability to uptake, lock in, and kill bacteria within their gel structure, enabling the cleansing of the wound bed at every dressing change. Finally, the treatment of severely infected wound in veterinary patient confirmed the effectiveness of gentamicin-loaded biomaterial. Biomaterial enriched with gentamicin possesses great potential to be used as a dressing material or sponge for the treatment of chronically infected wounds and surgical site infections. In turn, the zinc-loaded biomaterial may be used as a wound dressing to reduce and prevent microbial contamination.

Mesh Ti6Al4V Material Manufactured by Selective Laser Melting (SLM) as a Promising Intervertebral Fusion Cage

Intervertebral cages made of Ti6Al4V alloy show excellent osteoconductivity, but also higher stiffness, compared to commonly used polyether-ether-ketone (PEEK) materials, that may lead to a stress-shielding effect and implant subsidence. In this study, a metallic intervertebral fusion cage, with improved mechanical behavior, was manufactured by the introduction of a three-dimensional (3D) mesh structure to Ti6Al4V material, using an additive manufacturing method. Then, the mechanical and biological properties of the following were compared: (1) PEEK, with a solid structure, (2) 3D-printed Ti6Al4V, with a solid structure, and (3) 3D-printed Ti6Al4V, with a mesh structure. A load-induced subsidence test demonstrated that the 3D-printed mesh Ti6Al4V cage had significantly lower tendency (by 15%) to subside compared to the PEEK implant. Biological assessment of the samples proved that all tested materials were biocompatible. However, both titanium samples (solid and mesh) were characterized by significantly higher bioactivity, osteoconductivity, and mineralization ability, compared to PEEK. Moreover, osteoblasts revealed stronger adhesion to the surface of the Ti6Al4V samples compared to PEEK material. Thus, it was clearly shown that the 3D-printed mesh Ti6Al4V cage possesses all the features for optimal spinal implant, since it carries low risk of implant subsidence and provides good osseointegration at the bone-implant interface.

First Directional Measurement of Sub-MeV Solar Neutrinos with Borexino

We report the measurement of sub-MeV solar neutrinos through the use of their associated Cherenkov radiation, performed with the Borexino detector at the Laboratori Nazionali del Gran Sasso. The measurement is achieved using a novel technique that correlates individual photon hits of events to the known position of the Sun. In an energy window between 0.54 to 0.74 MeV, selected using the dominant scintillation light, we have measured 10 887_{-2103}^{+2386}(stat)±947(syst) (68% confidence interval) solar neutrinos out of 19 904 total events. This corresponds to a ^{7}Be neutrino interaction rate of 51.6_{-12.5}^{+13.9}  counts/(day·100  ton), which is in agreement with the standard solar model predictions and the previous spectroscopic results of Borexino. The no-neutrino hypothesis can be excluded with >5σ confidence level. For the first time, we have demonstrated the possibility of utilizing the directional Cherenkov information for sub-MeV solar neutrinos, in a large-scale, high light yield liquid scintillator detector. This measurement provides an experimental proof of principle for future hybrid event reconstruction using both Cherenkov and scintillation signatures simultaneously.

Lipoic Acid-Coated Silver Nanoparticles: Biosafety Potential on the Vascular Microenvironment and Antibacterial Properties

Purpose: To study and compare the antibacterial properties and the potential cytotoxic effects of commercially available uncoated silver nanoparticles (AgNPs) with lipoic acid coated silver nanoparticles (AgNPsLA) developed by our group. The antibacterial, cytotoxic, and hemolytic properties of those NPs were assessed with the main objective of investigating if AgNPsLA could maintain their antibacterial properties while improving their biosafety profile over uncoated AgNPs within the blood vessel’s microenvironment.

Methods: Comercially available uncoated 2.6 nm AgNPs and 2.5 nm AgNPsLA synthesized and characterized as previously described by our group, were used in this study. Antimicrobial activity was assessed on a wide range of pathogens and expressed by minimal inhibitory concentrations (MIC). Assessment of cytotoxicity was carried out on human umbilical vein endothelial cells (HUVEC) using an MTT test. Detection of reactive oxygen species, cell apoptosis/necrosis in HUVEC, and measurement of mitochondrial destabilization in HUVEC and platelets were performed by flow cytometry. The potential harmful effect of nanoparticles on red blood cells (RBCs) was investigated measuring hemoglobin and LDH released after exposure to NPs. Transmission electron microscopy was also used to determine if AgNPs and AgNPsLA could induce any ultrastructural changes on HUVEC cells and Staphylococcus aureus bacteria.

Results: AgNPs and AgNPsLA had antimicrobial properties against pathogens associated with catheter-related bloodstream infections. AgNPs, in contrast to AgNPsLA, induced ROS production and apoptosis in HUVEC, ultrastructural changes in HUVEC and S. aureus, depolarization of mitochondrial membrane in HUVEC and platelets, and also hemolysis.

Conclusion: AgNPsLA synthesized by our group have antimicrobial activity and a better biosafety profile than uncoated AgNPs of similar size. Those observations are of critical importance for the future in vivo investigations and the potential application of AgNPsLA in medical devices for human use.

Pulse shape analysis in Gerda Phase II

The GERmanium Detector Array (Gerda) collaboration searched for neutrinoless double- β decay in 76 Ge using isotopically enriched high purity germanium detectors at the Laboratori Nazionali del Gran Sasso of INFN. After Phase I (2011-2013), the experiment benefited from several upgrades, including an additional active veto based on LAr instrumentation and a significant increase of mass by point-contact germanium detectors that improved the half-life sensitivity of Phase II (2015-2019) by an order of magnitude. At the core of the background mitigation strategy, the analysis of the time profile of individual pulses provides a powerful topological discrimination of signal-like and background-like events. Data from regular 228 Th calibrations and physics data were both considered in the evaluation of the pulse shape discrimination performance. In this work, we describe the various methods applied to the data collected in Gerda Phase II corresponding to an exposure of 103.7 kg year. These methods suppress the background by a factor of about 5 in the region of interest around Q β β = 2039  keV, while preserving ( 81 ± 3 ) % of the signal. In addition, an exhaustive list of parameters is provided which were used in the final data analysis.

Offshore benthic habitat mapping based on object-based image analysis and geomorphometric approach. A case study from the Slupsk Bank, Southern Baltic Sea

Benthic habitat mapping is a rapidly growing field of underwater remote sensing studies. This study provides the first insight for high-resolution hydroacoustic surveys in the Slupsk Bank Natura 2000 site, one of the most valuable sites in the Polish Exclusive Zone of the Southern Baltic. This study developed a quick and transparent, automatic classification workflow based on multibeam echosounder and side-scan sonar surveys to classify benthic habitats in eight study sites within the Slupsk Bank. Different predictor variables, four supervised classifiers, and the generalisation approach, improving the accuracy of the developed model were evaluated. The results suggested a very high significance for the classification performance of specific geomorphometric features that were not used in benthic habitat mapping before. These include, e.g., Fuzzy Landform Element Classification, Multiresolution Index of the Valley Bottom Flatness, and Multiresolution Index of the Ridge Top Flatness. Comparison of classification results with manual maps demonstrated that Random Forest had the highest performance of four tested supervised classifiers. Because the current needs include benthic habitat mapping for the whole area of the Polish Exclusive Economic Zone, the key findings of this study may be further applied to extensive areas in the Polish waters and other vast areas worldwide.

Effect of Vitamin C/Hydrocortisone Immobilization within Curdlan-Based Wound Dressings on In Vitro Cellular Response in Context of the Management of Chronic and Burn Wounds

Bioactive dressings are usually produced using natural or synthetic polymers. Recently, special attention has been paid to β-glucans that act as immunomodulators and have pro-healing properties. The aim of this research was to use β-1,3-glucan (curdlan) as a base for the production of bioactive dressing materials (curdlan/agarose and curdlan/chitosan) that were additionally enriched with vitamin C and/or hydrocortisone to improve healing of chronic and burn wounds. The secondary goal of the study was to compressively evaluate biological properties of the biomaterials. In this work, it was shown that vitamin C/hydrocortisone-enriched biomaterials exhibited faster vitamin C release profile than hydrocortisone. Consecutive release of the drugs is a desired phenomenon since it protects wounds against accumulation of high and toxic concentrations of the bioactive molecules. Moreover, biomaterials showed gradual release of low doses of the hydrocortisone, which is beneficial during management of burn wounds with hypergranulation tissue. Among all tested variants of biomaterials, dressing materials enriched with hydrocortisone and a mixture of vitamin C/hydrocortisone showed the best therapeutic potential since they had the ability to significantly reduce MMP-2 synthesis by macrophages and increase TGF-β1 release by skin cells. Moreover, materials containing hydrocortisone and its blend with vitamin C stimulated type I collagen deposition by fibroblasts and positively affected their migration and proliferation. Results of the experiments clearly showed that the developed biomaterials enriched with bioactive agents may be promising dressings for the management of non-healing chronic and burn wounds.

Pharmacological cardioversion of recent-onset atrial fibrillation in patients with chronic kidney disease: sub-analysis of the CANT study

Purpose

Pharmacological cardioversion (PCV) is commonly a primary option for termination of recent-onset atrial fibrillation (AF) at the emergency departments (ED), and there are reports proving that antazoline is a noteworthy agent to restore sinus rhythm. This is a sub-analysis of the CANT study evaluating the effectiveness and safety of antazoline in patients with AF at different stages of chronic kidney disease (CKD).

Methods

Total n=777 patients admitted to ED for the urgent termination of AF were included into this analysis. We analysed the results concerning effectiveness and safety of PCV with special consideration of antazoline, in patients at 3 stages of CKD defined on the basis of eGFR (CKD-EPI): Group I ≥60 mL/min (n=531), Group II 45–59 mL/min (n=149), and Group III <45 mL/min (n=97). Primary end-point was the termination of AF, a restoration of a sinus rhythm and its persistence until discharge.

Results

Patients of group III were older and with higher prevalence of comorbidities, however, we have not found statistically significant differences in overall effectiveness of PCV in comparison with the other groups. In patients receiving amiodarone, the PCV success rate was similar in all the studied groups, but along with a renal function decline, it decreased in patients receiving antazoline (79.1 vs 35%; p<0.001), and it increased close to a significant manner in patients receiving propafenone (69.9 vs 100%; p=0.067; Figure). In patients of Group I, antazoline restored a sinus rhythm as effectively as propafenone and amiodarone, however in patients of Group III, both antazoline and amiodarone became less effective in restoring a sinus rhythm than propafenone (p=0.002 and p=0.034, respectively). The rate of safety endpoint was highest in patients of Group III (eGFR<45 mL/min), and it was significantly higher than in patients of Group I and II (p=0.008 and p=0.036, respectively). We have not observed antazoline-related adverse events in any of studied groups of patients.

Conclusion

This real-world registry analysis revealed a different influence of CKD on individual drug effectiveness, and while propafenone and amiodarone maintained their AF termination efficacy, antazoline became significantly less effective in restoring sinus rhythm. Its favourable safety profile has not changed.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): The study received no external funding

Polarization splitting with cubic crystals evaluated with synchrotron radiation

X-ray polarization-splitting crystals separate incident x rays into two components with perpendicular polarization by Bragg reflections at 45° from paired sets of internal planes. Here, the polarization-splitting properties of a germanium crystal are verified using incompletely polarized synchrotron radiation. Cleaner data would have come from a beam with a higher degree of polarization, which is achievable with small changes in the experimental geometry.

Characterization of inverted coaxial 76 Ge detectors in GERDA for future double- β decay experiments

Neutrinoless double- β decay of 76 Ge is searched for with germanium detectors where source and detector of the decay are identical. For the success of future experiments it is important to increase the mass of the detectors. We report here on the characterization and testing of five prototype detectors manufactured in inverted coaxial (IC) geometry from material enriched to 88% in 76 Ge. IC detectors combine the large mass of the traditional semi-coaxial Ge detectors with the superior resolution and pulse shape discrimination power of point contact detectors which exhibited so far much lower mass. Their performance has been found to be satisfactory both when operated in vacuum cryostat and bare in liquid argon within the Gerda setup. The measured resolutions at the Q-value for double- β decay of 76 Ge ( Q β β  = 2039 keV) are about 2.1 keV full width at half maximum in vacuum cryostat. After 18 months of operation within the ultra-low background environment of the GERmanium Detector Array (Gerda) experiment and an accumulated exposure of 8.5 kg · year, the background index after analysis cuts is measured to be 4 . 9 - 3.4 + 7.3 × 10 - 4 counts / ( keV · kg · year ) around Q β β . This work confirms the feasibility of IC detectors for the next-generation experiment Legend.

Superabsorbent curdlan-based foam dressings with typical hydrocolloids properties for highly exuding wound management

Effective management of chronic wounds with excessive exudate may be challenging for medical doctors. Over the years, there has been an increasing interest in the engineering of biomaterials, focusing on the development of polymer-based wound dressings to accelerate the healing of exuding wounds. The aim of this study was to use curdlan, which is known to support wound healing, as a base for the production of superabsorbent hybrid biomaterials (curdlan/agarose and curdlan/chitosan) with the intended use as wound dressings for highly exuding wound management. To evaluate the biomedical potential of the fabricated curdlan-based biomaterials, they were subjected to a comprehensive assessment of their microstructural, physicochemical, and biological properties. The obtained results showed that foam-like biomaterials with highly porous structure (66-77%) transform into soft gel after contact with the wound fluid, acting as typical hydrocolloid dressings. Novel biomaterials have the superabsorbent ability (1 g of the biomaterial absorbs approx. 15 ml of exudate) with horizontal wicking direction while keeping dry edges, and show water vapor transmission rate of approx. 1700-1800 g/m²/day which is recommended for optimal wound healing. Moreover, they are stable in the presence of collagenases, but prone to biodegradation in lysozyme solution (simulated infected wound environment). Importantly, the developed biomaterials are non-toxic and their surface hinders fibroblast attachment, which is essential during dressing changes to avoid damage to newly formed tissues in the wound bed. All mentioned features make the developed biomaterials promising candidates to be used as the wound dressings for the management of chronic wounds with moderate to high exudate.

Phasic Neuronal Firing in the Rodent Nucleus of the Solitary Tract ex vivo

Phasic pattern of neuronal activity has been previously described in detail for magnocellular vasopressin neurons in the hypothalamic paraventricular and supraoptic nuclei. This characteristic bistable pattern consists of alternating periods of electrical silence and elevated neuronal firing, implicated in neuropeptide release. Here, with the use of multi-electrode array recordings ex vivo, we aimed to study the firing pattern of neurons in the nucleus of the solitary tract (NTS) - the brainstem hub for homeostatic, cardio-vascular, and metabolic processes. Our recordings from the mouse and rat hindbrain slices reveal the phasic activity pattern to be displayed by a subset of neurons in the dorsomedial NTS subjacent to the area postrema (AP), with the inter-spike interval distribution closely resembling that reported for phasic magnocellular vasopressin cells. Additionally, we provide interspecies comparison, showing higher phasic frequency and firing rate of phasic NTS cells in mice compared to rats. Further, we describe daily changes in their firing rate and pattern, peaking at the middle of the night. Last, we reveal these phasic cells to be sensitive to α ₂ adrenergic receptors activation and to respond to electrical stimulation of the AP. This study provides a comprehensive description of the phasic neuronal activity in the rodent NTS and identifies it as a potential downstream target of the AP noradrenergic system.

Calibration of the Gerda experiment

The GERmanium Detector Array (Gerda) collaboration searched for neutrinoless double- β decay in 76 Ge with an array of about 40 high-purity isotopically-enriched germanium detectors. The experimental signature of the decay is a monoenergetic signal at Q β β = 2039.061 ( 7 )  keV in the measured summed energy spectrum of the two emitted electrons. Both the energy reconstruction and resolution of the germanium detectors are crucial to separate a potential signal from various backgrounds, such as neutrino-accompanied double- β decays allowed by the Standard Model. The energy resolution and stability were determined and monitored as a function of time using data from regular 228 Th calibrations. In this work, we describe the calibration process and associated data analysis of the full Gerda dataset, tailored to preserve the excellent resolution of the individual germanium detectors when combining data over several years.

Final Results of GERDA on the Search for Neutrinoless Double-β Decay

The GERmanium Detector Array (GERDA) experiment searched for the lepton-number-violating neutrinoless double-β (0νββ) decay of ^{76}Ge, whose discovery would have far-reaching implications in cosmology and particle physics. By operating bare germanium diodes, enriched in ^{76}Ge, in an active liquid argon shield, GERDA achieved an unprecedently low background index of 5.2×10^{-4} counts/(keV kg yr) in the signal region and met the design goal to collect an exposure of 100 kg yr in a background-free regime. When combined with the result of Phase I, no signal is observed after 127.2 kg yr of total exposure. A limit on the half-life of 0νββ decay in ^{76}Ge is set at T_{1/2}>1.8×10^{26}  yr at 90% C.L., which coincides with the sensitivity assuming no signal.

Collagen maturity and mineralization in mesenchymal stem cells cultured on the hydroxyapatite-based bone scaffold analyzed by ATR-FTIR spectroscopic imaging

Modern bone tissue engineering is based on the use of implants in the form of biomaterials, which are used as scaffolds for osteoprogenitor or stem cells. The task of the scaffolds is to temporarily sustain the function, proliferation and differentiation of bone tissue to enable its regeneration. The aim of this work is to use the macro ATR-FTIR spectroscopic imaging for analysis of the ceramic-based biomaterial (chitosan/β-1,3-glucan/hydroxyapatite). Specifically, during long-term culture of mesenchymal cells derived from adipose tissue (ADSCs) and bone marrow (BMDSCs) on the surface of scaffold. Infrared spectroscopy allows the acquisition of information on both the organic and inorganic parts of the tested composite. This innovative spectroscopic approach proved to be very suitable for studying the formation of new bone tissue and ECM components, sample staining and demineralization are not required and consequently the approach is rapid and cost-effective. The novelty of this study focuses on the innovatory use of ATR-FTIR imaging to evaluate the molecular structure and maturity of collagen as well as mineral matrix formation and crystallization in the context of bone regenerative medicine. Our research has shown that the biomaterial investigated on this work facilitates the formation of valid bone ECM of the stem cells types studied, as a result of the synthesis of type I collagen and mineral content deposition. Nevertheless, ADSC cells have been proven to produce a greater amount of collagen with a lower content of helical secondary structures, at the same time showing a higher mineralization intensity compared to BMDSC cells. Considering the above results, it could be stated that the developed scaffold is a promising material for biomedical applications, including modification of bone implants to increase their biocompatibility.

Circadian actions of orexins on the retinorecipient lateral geniculate complex in rat

Key points

Rhythmic processes in living organisms are controlled by biological clocks. The orexinergic system of the lateral hypothalamus carries circadian information to provide arousal for the brain during the active phase.

Here, we show that orexins exert an excitatory action in three parts of the lateral geniculate nucleus (LGN), in particular upon directly retinorecipient neurons in the non‐image forming visual structures.

We provide evidence for the high nocturnal levels of orexins with stable circadian expression of predominant orexin receptor 2 in the LGN.

Our data additionally establish the convergence of orexinergic and pituitary adenylate cyclase (PAC)‐activating peptide/PAC1 receptor systems (used by melanopsin‐expressing retinal ganglion cells), which directly regulates responses to the retinal input.

These results help us better understand circadian orexinergic control over the non‐image forming subcortical visual system, forming the animal's preparedness for the behaviourally active night.

Abstract

The orexinergic system of the lateral hypothalamus is tightly interlinked with the master circadian clock and displays daily variation in activity to provide arousal‐related excitation for the plethora of brain structures in a circadian manner. Here, using a combination of electrophysiological, optogenetic, histological, molecular and neuronal tracing methods, we explore a particular link between orexinergic and visual systems in rat. The results of the present study demonstrate that orexinergic fibre density at the area of subcortical visual system exerts a clear day to night variability, reaching a maximum at behaviourally active night. We also show pronounced electrophysiological activations of neurons in the lateral geniculate nucleus by orexin A through 24 h, via identified distinct orexin receptors, with the ventrolateral geniculate displaying a daily cycle of responsiveness. In addition, for the first time, we provide a direct evidence for orexins to act on retinorecipient neurons with a high convergence of orexinergic and putatively retinal pituitary adenylate cyclase (PAC)‐activating peptide/PAC1 receptor systems. Altogether, the present study ties orexins to non‐image forming visual structures with implications for circadian orexinergic modulation of neurons, which process information on ambient light levels.

Rhythmic processes in living organisms are controlled by biological clocks. The orexinergic system of the lateral hypothalamus carries circadian information to provide arousal for the brain during the active phase.

Here, we show that orexins exert an excitatory action in three parts of the lateral geniculate nucleus (LGN), in particular upon directly retinorecipient neurons in the non‐image forming visual structures.

We provide evidence for the high nocturnal levels of orexins with stable circadian expression of predominant orexin receptor 2 in the LGN.

Our data additionally establish the convergence of orexinergic and pituitary adenylate cyclase (PAC)‐activating peptide/PAC1 receptor systems (used by melanopsin‐expressing retinal ganglion cells), which directly regulates responses to the retinal input.

These results help us better understand circadian orexinergic control over the non‐image forming subcortical visual system, forming the animal's preparedness for the behaviourally active night.

Ex vivo determination of chitosan/curdlan/hydroxyapatite biomaterial osseointegration with the use of human trabecular bone explant: New method for biocompatibility testing of bone implants reducing animal tests

Permanent orthopedic/dental implants should reveal good osseointegration, which is defined as an ability of the biomaterial to form a direct connection with the surrounding host bone tissue after its implantation into the living organism. Currently, biomaterial osseointegration is confirmed exclusively with the use of in vivo animal tests. This study presents for the first time ex vivo determination of osseointegration process using human trabecular bone explant that was drilled and filled with the chitosan/curdlan/hydroxyapatite biomaterial, followed by its long-term culture under in vitro conditions. Within this study, it was clearly proved that tested biomaterial allows for the formation of the connection with bone explant since osteoblasts, having ability to produce bone extracellular matrix (type I collagen, fibronectin), were detected at a bone-implant interface by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Importantly, in this research it was demonstrated by Live/Dead staining and CLSM imaging that human bone explants may stay alive for a long period of time (at least approx. 50 days) during their culture under in vitro conditions. Therefore, ex vivo bone explant, which is a heterogeneous tissue containing many different cell types, may serve as an excellent model to test biomaterial osseointegration during comparative and preliminary studies, reducing animal tests which is compatible with the principles of '3Rs', aiming to Replace, Reduce and Refine the use of animals wherever possible.

Intra-operative fluorescence angiography is reproducible and reduces the rate of anastomotic leak after colorectal resection for cancer: a prospective case-matched study

AIM

Intra-operative fluorescence angiography (IOFA) with indocyanine green provides information on tissue perfusion that may help prevent an anastomotic leak (AL). The aim of this study was to assess the impact of IOFA on outcomes after left-sided colonic or low anterior resection with anastomosis for colorectal cancer.

METHODS

All patients with left-sided colonic or rectal cancer, operated between June 2017 and December 2018, were prospectively included. IOFA has been routinely implemented since May 2018. Reproducibility of IOFA, after a 1:1 matching for relevant clinical risk factors of AL, was studied in patients with IOFA (IOFA+) and without IOFA (IOFA-). Outcomes were compared in terms of postoperative events such as clinically relevant AL as the primary end-point.

RESULTS

In the IOFA+ group, changing of the initially planned colon transection due to inadequate perfusion occurred in five out of 46 patients (10.9%). Agreement between intra-operative assessment and postoperative blind review of IOFA was deemed strong (Cohen's kappa index 0.893, 95% CI 0.788-0.998, P < 0.001). Among 111 patients, 42 matched patients were included in each group. There was significantly more clinically relevant AL in the IOFA- group compared to the IOFA+ group (16.7% vs 2.4%, P = 0.026) involving significantly more anastomotic dehiscence which required re-intervention (19% vs 2.4%, P = 0.014). Additionally, more descending colon ischaemia/necrosis was observed in the IOFA- group compared with the IOFA+ group (9.5% vs 0%, P = 0.040).

CONCLUSION

In this prospective case-matched study, IOFA decreased the occurrence of clinically relevant AL due to necrosis of the descending colon or anastomosis. Upon blind review, perfusion assessment using IOFA was reproducible.

Positive Effect of Cold Atmospheric Nitrogen Plasma on the Behavior of Mesenchymal Stem Cells Cultured on a Bone Scaffold Containing Iron Oxide-Loaded Silica Nanoparticles Catalyst

Low-temperature atmospheric pressure plasma was demonstrated to have an ability to generate different reactive oxygen and nitrogen species (RONS), showing wide biological actions. Within this study, mesoporous silica nanoparticles (NPs) and Fe_xO_y/NPs catalysts were produced and embedded in the polysaccharide matrix of chitosan/curdlan/hydroxyapatite biomaterial. Then, basic physicochemical and structural characterization of the NPs and biomaterials was performed. The primary aim of this work was to evaluate the impact of the combined action of cold nitrogen plasma and the materials produced on proliferation and osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells (ADSCs), which were seeded onto the bone scaffolds containing NPs or Fe_xO_y/NPs catalysts. Incorporation of catalysts into the structure of the biomaterial was expected to enhance the formation of plasma-induced RONS, thereby improving stem cell behavior. The results obtained clearly demonstrated that short-time (16s) exposure of ADSCs to nitrogen plasma accelerated proliferation of cells grown on the biomaterial containing Fe_xO_y/NPs catalysts and increased osteocalcin production by the cells cultured on the scaffold containing pure NPs. Plasma activation of Fe_xO_y/NPs-loaded biomaterial resulted in the formation of appropriate amounts of oxygen-based reactive species that had positive impact on stem cell proliferation and at the same time did not negatively affect their osteogenic differentiation. Therefore, plasma-activated Fe_xO_y/NPs-loaded biomaterial is characterized by improved biocompatibility and has great clinical potential to be used in regenerative medicine applications to improve bone healing process.

First Search for Bosonic Superweakly Interacting Massive Particles with Masses up to 1 MeV/c^{2} with GERDA

We present the first search for bosonic superweakly interacting massive particles (super-WIMPs) as keV-scale dark matter candidates performed with the GERDA experiment. GERDA is a neutrinoless double-β decay experiment which operates high-purity germanium detectors enriched in ^{76}Ge in an ultralow background environment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy. Searches were performed for pseudoscalar and vector particles in the mass region from 60  keV/c^{2} to 1  MeV/c^{2}. No evidence for a dark matter signal was observed, and the most stringent constraints on the couplings of super-WIMPs with masses above 120  keV/c^{2} have been set. As an example, at a mass of 150  keV/c^{2} the most stringent direct limits on the dimensionless couplings of axionlike particles and dark photons to electrons of g_{ae}<3×10^{-12} and α^{'}/α<6.5×10^{-24} at 90% credible interval, respectively, were obtained.

Cellular Response to Vitamin C-Enriched Chitosan/Agarose Film with Potential Application as Artificial Skin Substitute for Chronic Wound Treatment

The treatment of chronic wounds is still a meaningful challenge to physicians. The aim of this work was to produce vitamin C-enriched chitosan/agarose (CHN/A) film that could serve as potential artificial skin substitute for chronic wound treatment. The biomaterial was fabricated by a newly developed and simplified method via mixing acidic chitosan solution with alkaline agarose solution that allowed to obtain slightly acidic pH (5.97) of the resultant material, which is known to support skin regeneration. Vitamin C was immobilized within the matrix of the film by entrapment method during production process. Produced films (CHN/A and CHN/A + vit C) were subjected to comprehensive evaluation of cellular response with the use of human skin fibroblasts, epidermal keratinocytes, and macrophages. It was demonstrated that novel biomaterials support adhesion and growth of human skin fibroblasts and keratinocytes, have ability to slightly reduce transforming growth factor-beta 1 (TGF-β1) (known to be present at augmented levels in the epidermis of chronic wounds), and increase platelet-derived growth factor-BB (PDGF-BB) secretion by the cells. Nevertheless, addition of vitamin C to the biomaterial formulation does not significantly improve its biological properties due to burst vitamin release profile. Obtained results clearly demonstrated that produced CHN/A film has great potential to be used as cellular dermal, epidermal, or dermo-epidermal graft pre-seeded with human skin cells for chronic wound treatment.

Characterization of 30 76 Ge enriched Broad Energy Ge detectors for GERDA Phase II

The GERmanium Detector Array (Gerda) is a low background experiment located at the Laboratori Nazionali del Gran Sasso in Italy, which searches for neutrinoless double-beta decay of 76 Ge into 76 Se+2e - . Gerda has been conceived in two phases. Phase II, which started in December 2015, features several novelties including 30 new ⁷⁶Ge enriched detectors. These were manufactured according to the Broad Energy Germanium (BEGe) detector design that has a better background discrimination capability and energy resolution compared to formerly widely-used types. Prior to their installation, the new BEGe detectors were mounted in vacuum cryostats and characterized in detail in the Hades underground laboratory in Belgium. This paper describes the properties and the overall performance of these detectors during operation in vacuum. The characterization campaign provided not only direct input for Gerda Phase II data collection and analyses, but also allowed to study detector phenomena, detector correlations as well as to test the accuracy of pulse shape simulation codes.

Asymmetrically Positioned Flagellar Control Units Regulate Human Sperm Rotation

Ion channels control sperm navigation within the female reproductive tract and, thus, are critical for their ability to find and fertilize an egg. The flagellar calcium channel CatSper controls sperm hyperactivated motility and is dependent on an alkaline cytoplasmic pH. The latter is accomplished by either proton transporters or, in human sperm, via the voltage-gated proton channel Hv1. To provide concerted regulation, ion channels and their regulatory proteins must be compartmentalized. Here, we describe flagellar regulatory nanodomains comprised of Hv1, CatSper, and its regulatory protein ABHD2. Super-resolution microscopy revealed that Hv1 is distributed asymmetrically within bilateral longitudinal lines and that inhibition of this channel leads to a decrease in sperm rotation along the long axis. We suggest that specific distribution of flagellar nanodomains provides a structural basis for the selective activation of CatSper and subsequent flagellar rotation. The latter, together with hyperactivated motility, enhances the fertility of sperm.

Changes in growth hormone secretion and leptin receptor mRNA expression under the influence of leptin and adrenocorticotropin in pituitary cells of early weaned ewe lambs

Early weaning of ewe lambs strongly stimulates the hypothalamic-pituitary-adrenal axis and is associated with suppressed growth rate despite the increased food intake. At the same time, plasma leptin concentration increases only slightly or undetectably. To better understand this atypical interdependence among somatic stress, leptin, and lamb growth rate, we analyzed impact of leptin and/or adrenocorticotropic hormone (ACTH) on growth hormone (GH) secretion as well as the effect of ACTH on mRNA expression of two splice variants of leptin receptor (LEPRa, LEPRb) in pituitary cells isolated from early weaned ewe lambs. The GH secretion under the influence of leptin and/or ACTH depended on the timing of exposure and hormone concentration. After 6 - 30 h, GH secretion increased under 10^-11 - 10^-8 M leptin (P ≤ 0.05). However, after 24 - 30 h, GH secretion significantly increased only in cells exposed to both leptin and ACTH compared to culture with leptin only. Simultaneously, there was a significant (P ≤ 0.05) decrease in leptin receptor mRNA expression under the influence of ACTH at 10^-8 - 10^-6 M after 12 - 30 and 24 - 30 h for LEPRa and LEPRb, respectively. ACTH-related downregulation of LEPR mRNA was associated with a significant (P ≤ 0.05) reduction in leptin-stimulated GH secretion, also after 24 - 30 hours. Thus, the timing of ACTH exposure, followed by decreased leptin receptor mRNA, converged with the timing of decreased GH secretion under the influence of leptin with ACTH. The ACTH-induced downregulation of LEPR mRNA therefore may underlie the decrease in GH. These results show a direct role for leptin, ACTH, and leptin receptor expression in modulation of pituitary GH secretion in early weaned ewe lambs. During the early weaning-induced stress response, the ACTH-mediated decrease in sensitivity of pituitary cells to leptin may abolish a stimulatory effect of leptin on GH secretion and explain in part, the reduction in lamb growth rate.

Probing Majorana neutrinos with double-β decay

A discovery that neutrinos are Majorana fermions would have profound implications for particle physics and cosmology. The Majorana character of neutrinos would make possible the neutrinoless double-β (0νββ) decay, a matter-creating process without the balancing emission of antimatter. The GERDA Collaboration searches for the 0νββ decay of ⁷⁶Ge by operating bare germanium detectors in an active liquid argon shield. With a total exposure of 82.4 kg⋅year, we observe no signal and derive a lower half-life limit of T _1/2 > 0.9 × 10²⁶ years (90% C.L.). Our T _1/2 sensitivity, assuming no signal, is 1.1 × 10²⁶ years. Combining the latter with those from other 0νββ decay searches yields a sensitivity to the effective Majorana neutrino mass of 0.07 to 0.16 electron volts.

Publisher Correction: Oblique-plane single-molecule localization microscopy for tissues and small intact animals

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Effects of functionalized silver nanoparticles on aggregation of human blood platelets

PURPOSE

We studied the effects of silver nanoparticles (AgNPs) on human blood platelet function. We hypothesized that AgNPs, a known antimicrobial agent, can be used as blood-compatible, "ideal material'' in medical devices or as a drug delivery system. Therefore, the aim of the current study was to investigate if functionalized AgNPs affect platelet function and platelets as well as endothelial cell viability in vitro.

METHODS

AgNPs, functionalized with reduced glutathione (GSH), polyethylene glycol (PEG) and lipoic acid (LA) were synthesized. Quartz crystal microbalance with dissipation was used to measure the effect of AgNPs on platelet aggregation. Platelet aggregation was measured by changes in frequency and dissipation, and the presence of platelets on the sensor surface was confirmed and imaged by phase contrast microscopy. Flow cytometry was used to detect surface abundance of platelet receptors. Lactate dehydrogenase test was used to assess the potential cytotoxicity of AgNPs on human blood platelets, endothelial cells, and fibroblasts. Commercially available ELISA tests were used to measure the levels of thromboxane B2 and metalloproteinases (MMP-1, MMP-2) released by platelets as markers of platelet activation.

RESULTS

2 nm AgNPs-GSH, 3.7 nm AgNPs-PEG both at 50 and 100 µg/mL, and 2.5 nm AgNPs-LA at 100 µg/mL reduced platelet aggregation, inhibited collagen-mediated increase in total P-selectin and GPIIb/IIIa, TXB2 formation, MMP-1, and MMP-2 release. The tested AgNPs concentrations were not cytotoxic as they did not affect, platelet, endothelial cell, or fibroblast viability.

CONCLUSION

All tested functionalized AgNPs inhibited platelet aggregation at nontoxic concentrations. Therefore, functionalized AgNPs can be used as an antiplatelet agent or in design and manufacturing of blood-facing medical devices, such as vascular grafts, stents, heart valves, and catheters.

Light-Assisted Diazonium Functionalization of Graphene and Spatial Heterogeneities in Reactivity

The reaction of monolayer graphene with aryl diazonium salts is a popular approach for functionalizing graphene under ambient conditions. We here apply interference reflection microscopy (IRM), a label-free optical technique, to study the in situ reaction dynamics of the representative diazonium reaction of graphene with 4-nitrobenzenediazonium tetrafluoroborate (4-NBD) at high spatiotemporal resolution and further correlate results with atomic force microscopy, Raman spectroscopy, and infrared scattering scanning near-field optical microscopy. Interestingly, we find the reaction to be significantly promoted by a low (0.5 W/cm²) level of blue visible light, whereas at the same intensity level, red light has negligible effects on reaction rate. We further report rich spatial heterogeneities for the reaction, including enhanced reactivity at graphene edges and an unexpected flake-to-flake variation in reaction rate. Moreover, we demonstrate direct photopatterning for the 4-NBD functionalization, achieving 400 nm patterning resolution.

Role of donor HLA class I mismatch, KIR-ligand mismatch and HLA:KIR pairings in hematological malignancy relapse after unrelated hematopoietic stem cell transplantation

HLA are functional in cancer immunosurveillance in adaptive and innate immunity pathways. In unrelated hematopoietic stem cell transplantation (HSCT) in 688 patients with hematological malignancies we compared antitumor efficacy of transplant in three models including the level of: (a) donor-recipient HLA class I mismatch, (b) KIR-ligand mismatch, (c) post-transplant cognate HLA:KIR pairing. The effects were directly compared in multivariate models with backward elimination including all three effects in initial model. In final multivariate model HLA mismatch and KIR-ligand mismatch levels were eliminated and HLA:KIR-dependent NK cell licensing effect remained independent prognostic factor for DFS, relapse/progression incidence, and overall survival (OS). These results suggested that NK cell licensing via cognate HLA:KIR pairs is primarily functional in cancer immunosurveillance in HSCT.

Optical Microscopy Unveils Rapid, Reversible Electrochemical Oxidation and Reduction of Graphene

We unveil the reaction dynamics of monolayer graphene in electrochemical oxidation and reduction processes through interference reflection optical microscopy. At 300 nm spatial resolution and 200 ms temporal resolution, we reveal rapid electrochemical oxidation of graphene, as well as its efficient electrochemical reduction back to the unoxidized state. We identify 1.4 V (vs Ag/AgCl) as the onset voltage for oxidation and show that the process is driven by free radicals generated in the electrolysis of water and so fully suppressible by a radical-trapping molecule. Moreover, we find the oxidation process to be spatially heterogeneous at the nanoscale, defect- and history-dependent, and characterized by a self-limiting effect unique to the two-dimensional system. We further demonstrate that electrochemical reduction rapidly reverses the oxidized graphene back to the unoxidized state in a controlled manner and find strong dependency of reduction speed on the reduction voltage and pH, from which we conclude a one-to-one relationship between protons and electrons in the reduction process. Besides elucidating the electrochemical reaction mechanisms of graphene, our results point to new pathways to the controlled generation and fine-tuning of graphene derivatives through electrochemistry.

Evaluation of ultrasonic vocalizations in a neurodevelopmental model of schizophrenia during the early life stages of rats

In an animal neurodevelopmental model of schizophrenia, we investigated ultrasonic communication and social behavior in male and female rats. Pregnant dams were treated with methylazoxymethanol acetate (MAM; 22 mg/kg) at 17 days of gestation. First, we examined the ultrasonic vocalizations (USVs) emitted by 8-day-old pups isolated from their mothers and placed in a familiar or an unfamiliar environment. Second, we assessed tickling-induced USVs, social play (SP) behavior and accompanying USVs in 30-day-old juveniles. Independent of the prenatal treatment, sex differences were noted at both ages. In the pups isolated from their mothers, compared to the females, the males produced flatter calls with a lower frequency. Compared to the females, the tickling-induced male USVs were characterized by a higher frequency, and the male SP-induced USVs showed a broader bandwidth and more modulated structure. Additionally, the numbers of both SP-induced USVs and SP episodes in the males were higher than those in the females. In contrast, the MAM exposure reduced the ultrasonic communication and social behavior independent of age almost equally in the male and female rats. The MAM-exposed isolated pups and juveniles experiencing tickling and social interaction displayed lower USV bandwidths, suggesting that the complexity of their ultrasonic communication was reduced. In addition, the MAM-exposed juveniles demonstrated a lower number of 50-kHz "happy calls" and decreased SP duration, which is suggestive of social withdrawal or negative-like symptoms. These data demonstrate that young MAM-exposed rats display an atypical repertoire of USVs and reduced play behavior suggestive of communication deficits associated with schizophrenia.

Constraints on Sub-GeV Dark-Matter-Electron Scattering from the DarkSide-50 Experiment

We present new constraints on sub-GeV dark-matter particles scattering off electrons based on 6780.0 kg d of data collected with the DarkSide-50 dual-phase argon time projection chamber. This analysis uses electroluminescence signals due to ionized electrons extracted from the liquid argon target. The detector has a very high trigger probability for these signals, allowing for an analysis threshold of three extracted electrons, or approximately 0.05 keVee. We calculate the expected recoil spectra for dark matter-electron scattering in argon and, under the assumption of momentum-independent scattering, improve upon existing limits from XENON10 for dark-matter particles with masses between 30 and 100  MeV/c^{2}.

Low-Mass Dark Matter Search with the DarkSide-50 Experiment

We present the results of a search for dark matter weakly interacting massive particles (WIMPs) in the mass range below 20  GeV/c^{2} using a target of low-radioactivity argon with a 6786.0 kg d exposure. The data were obtained using the DarkSide-50 apparatus at Laboratori Nazionali del Gran Sasso. The analysis is based on the ionization signal, for which the DarkSide-50 time projection chamber is fully efficient at 0.1  keVee. The observed rate in the detector at 0.5  keVee is about 1.5  event/keVee/kg/d and is almost entirely accounted for by known background sources. We obtain a 90% C.L. exclusion limit above 1.8  GeV/c^{2} for the spin-independent cross section of dark matter WIMPs on nucleons, extending the exclusion region for dark matter below previous limits in the range 1.8-6  GeV/c^{2}.

Optical characterization of surface adlayers and their compositional demixing at the nanoscale

Under ambient conditions, the behavior of a solid surface is often dominated by a molecularly thin adsorbed layer (adlayer) of small molecules. Here we develop an optical approach to unveil the nanoscale structure and composition of small-molecule adlayers on glass surfaces through spectrally resolved super-resolution microscopy. By recording the images and emission spectra of millions of individual solvatochromic molecules that turn fluorescent in the adlayer phase, we obtain ~30 nm spatial resolution and achieve concurrent measurement of local polarity. This allows us to establish that the adlayer dimensionality gradually increases through a sequence of 0D (nanodroplets), 1D (nano-lines), and 2D (films) for liquids of increasing polarity. Moreover, we find that in adlayers, a solution of two miscible liquids spontaneously demixes into nanodroplets of different compositions that correlate strongly with droplet size and location. We thus reveal unexpectedly rich structural and compositional behaviors of surface adlayers at the nanoscale.

Characterization of adsorbed molecular layers on surfaces is the key to wide-ranging applications, but elucidating the structure and composition of such adlayers remains challenging. Here the authors develop an approach to unveil the nanoscale structure and composition of adlayers through spectrally resolved super-resolution microscopy.