Sensing approaches for the discrimination of small molecules and multivalent analytes

Differential arrays, composed of receptors that are capable of generating unique patterns of responses, have been shown to be useful for discrimination of molecular analytes. Herein, differential arrays have been developed and utilized for the discrimination of small molecule and multivalent biological analytes using cross-reactive receptors. A variety of carboxylate-binding guanidinium-based receptors were tested for their ability to discriminate carboxylate enantiomers. Lanthanide complexes showed the most promising enantiodifferentiation. A dynamic receptor for multivalent biological analytes was developed using self-assembling components designed to target cancer cell lines in a cross-reactive manner. Using this differential array, cancer cell lines of different tissue origin were classified using principal component analysis. The receptors in the array responded to targets as hypothesized but also behaved in a cross-reactive manner that allowed for analyte differentiation. The classification response of the array was reproducible. Boronic acid receptors and receptor arrays were also developed for discrimination of cell surface glycans. In this work, the success of cross-reactive receptors with designed components in differential sensing for small molecules as well as complex multivalent analytes is demonstrated.Chemistr

On the Analysis of Intermediate-Energy Coulomb Excitation Experiments

In a recent publication (Bertulani et al., PLB 650 (2007) 233 and arXiv:0704.0060v2) the validity of analysis methods used for intermediate-energy Coulomb excitation experiments was called into question. Applying a refined theory large corrections of results in the literature seemed needed. We show that this is not the case and that the large deviations observed are due to the use of the wrong experimental parameters. We furthermore show that an approximate expression derived by Bertulani et al. is in fact equivalent to the theory of Winther and Alder (NPA 319 (1979) 518), an analysis method often used in the literature.Comment: 10 pages, 1 figure, submitted to PL

Partitioning the two-leg spin ladder in Ba2Cu1– xZnxTeO6 : from magnetic order through spin-freezing to paramagnetism

E.J.C., O.M., and C.P. acknowledge financial support from the Leverhulme Trust Research Project Grant No. RPG-2017-109. O.M. is grateful for funding via the Leverhulme Trust Early Career Fellowship ECF-2021-170. A.S.G. acknowledges funding through an EPSRC Early Career Fellowship EP/ T011130/1. A.S.G. and H.T. acknowledge funding through the Humboldt Foundation and the Max Planck Institute for Solid State Research. The authors thank the Science and Technology Facilities Council for beamtime allocated at ISIS through proposal RB1990046 (DOI: 10. 5286/ISIS.E.RB1990046) and the Swiss Muon Source at the Paul Scherrer Institute through proposal numbers 20150959 and 20211440. The authors are grateful for access to the MPMS3 instrument at The Royce Discovery Centre at the University of Sheffield (EPSRC grant no. EP/R00661X/1) and the PPMS instrument at the University of St. Andrews (EPSRC grant no. EP/T031441/1).Ba2CuTeO6 has attracted significant attention as it contains a two-leg spin ladder of Cu2+ cations that lies in close proximity to a quantum critical point. Recently, Ba2CuTeO6 has been shown to accommodate chemical substitutions, which can significantly tune its magnetic behavior. Here, we investigate the effects of substitution for non-magnetic Zn2+ impurities at the Cu2+ site, partitioning the spin ladders. Results from bulk thermodynamic and local muon magnetic characterization on the Ba2Cu1 – xZnxTeO6 solid solution (0 ≤ x ≤ 0.6) indicate that Zn2+ partitions the Cu2+ spin ladders into clusters and can be considered using the percolation theory. As the average cluster size decreases with increasing Zn2+ substitution, there is an evolving transition from long-range order to spin-freezing as the critical cluster size is reached between x = 0.1 to x = 0.2, beyond which the behavior became paramagnetic. This demonstrates well-controlled tuning of the magnetic disorder, which is highly topical across a range of low-dimensional Cu2+-based materials. However, in many of these cases, the chemical disorder is also relatively strong in contrast to Ba2CuTeO6 and its derivatives. Therefore, Ba2Cu1 – xZnxTeO6 provides an ideal model system for isolating the effect of defects and segmentation in low-dimensional quantum magnets.Publisher PDFPeer reviewe

Competing particle–hole excitations in ³⁰Na: Constraining state-of-the-art effective interactions

The odd–odd nucleus ³⁰Na is studied via a one-proton, one-proton–one-neutron and one-neutron removal reaction using an intermediate-energy ³¹Mg, ³²Mg and ³¹Na radioactive ion beam, respectively. Combining high-resolution γ-ray spectroscopy with the selectivity of the three reaction mechanisms, we are able to distinguish multiple particle–hole configurations. Negative-parity states in ³⁰Na are observed for the first time, providing an important measure of the excitation of the 1p1h/3p3h configuration and hence the sd–pf shell gap. The extracted band structures and level energies serve as invaluable input for the theoretical refinement of the effective interactions used in this region

Lifetime measurement of the 2₁⁺ state in ⁷⁴Rb and isospin properties of quadrupole transition strengths at N = Z

Self-conjugate nuclei in the A ≈ 70–80 region have attracted a great deal of attention due to phenomena such as shape coexistence and increasing collectivity along the N=Zline. We investigate the structure of nuclei in this region through lifetime measurements using the GRETINA array. The first implementation of the Differential Recoil Distance Doppler Shift technique with fast radioactive beams is demonstrated and verified through a measurement of the well-known B(E2; 2₁⁺→ 0₁⁺)transition strength in ⁷⁴Kr. The method is then applied to determine the B(E2; 2₁⁺→ 0₁⁺) transition strength in ⁷⁴Rb, the heaviest odd–odd N=Z nucleus for which this quantity has been determined. This result and extended systematics along N=Z suggest the dominance of the isoscalar part of the quadrupole transition strengths in self-conjugate nuclei, as well as the possible presence of shape coexistence in ⁷⁴Rb

Constraining the rp-process by measuring 23

The 23Al(p, γ)24Si stellar reaction rate has a significant impact on the light-curve emitted in X-ray bursts. Theoretical calculations show that the reaction rate is mainly determined by the properties of direct capture as well as low-lying 2+ states and a possible 4+ state in 24Si. Currently, there is little experimental information on the properties of these states. In this proceeding we will present a new experimental study to investigate this reaction, using the surrogate reaction 23Al(d,n) at 47 AMeV at the National Superconducting Cyclotron Laboratory (NSCL). We will discuss our new experimental setup which allows us to use full kinematics employing the Gamma-Ray Energy Tracking In-beam Nuclear Array (GRETINA) to detect the γ-rays following the de-excitation of excited states of the reaction products and the Low Energy Neutron Detector Array (LENDA) to detect the recoiling neutrons. The S800 was used for identification of the 24Si recoils. As a proof of principle to show the feasibility of this concept the Q-value spectrum of 22Mg(d,n)23Al is reconstructed

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.Peer reviewe

Reaching into the N = 40 Island of Inversion with Nucleon Removal Reactions

One ambitious goal of nuclear physics is a predictive model of all nuclei, including the ones at the fringes of the nuclear chart which may remain out of experimental reach. Certain regions of the chart are providing formidable testing grounds for nuclear models in this quest as they display rapid structural evolution from one nucleus to another or phenomena such as shape coexistence. Observables measured for such nuclei can confirm or refute our understanding of the driving forces of the evolution of nuclear structure away from stability where textbook nuclear physics has been proven to not apply anymore. This paper briefly reviews the emerging picture for the very neutron-rich Fe, Cr, and Ti isotopes within the so-called N=40 island of inversion as obtained with nucleon knockout reactions. These have provided some of the most detailed nuclear spectroscopy in very neutron-rich nuclei produced at rare-isotope facilities. The results indicate that our current understanding, as encoded in large-scale shell-model calculations, appears correct with exciting predictions for the N=40 island of inversion left to be proven in the experiment. A bright future emerges with predictions of continued shell evolution and shape coexistence out to neutron number N=50, below 78Ni on the chart of nuclei