Broadband CPW-based impedance-transformed Josephson parametric amplifier

Quantum-limited Josephson parametric amplifiers play a pivotal role in advancing the field of circuit quantum electrodynamics by enabling the fast and high-fidelity measurement of weak microwave signals. Therefore, it is necessary to develop robust parametric amplifiers with low noise, broad bandwidth, and reduced design complexity for microwave detection. However, current broadband parametric amplifiers either have degraded noise performance or rely on complex designs. Here, we present a device based on the broadband impedance-transformed Josephson parametric amplifier (IMPA) that integrates a horn-like coplanar waveguide (CPW) transmission line, which significantly decreases the design and fabrication complexity, while keeping comparable performance. The device shows an instantaneous bandwidth of 700(200) MHz for 15(20) dB gain with an average saturation power of -110 dBm and near quantum-limited added noise. The operating frequency can be tuned over 1.4 GHz using an external flux bias. We further demonstrate the negligible back-action from our device on a transmon qubit. The amplification performance and simplicity of our device promise its wide adaptation in quantum metrology, quantum communication, and quantum information processing.Comment: 11 pages, 8 figure

Assessment of immunotherapy response in intracranial malignancy using semi-automatic segmentation on magnetic resonance images

ObjectiveTo explore multi-aspect radiologic assessment of immunotherapy response in intracranial malignancies based on a semi-automatic segmentation technique, and to explore volumetric thresholds with good performance according to RECIST 1.1 thresholds.MethodsPatients diagnosed with intracranial malignancies and treated with immunotherapy were included retrospectively. In all MR images, target lesions were measured using a semi-automatic segmentation technique that could intelligently generate visual diagrams including RECIST 1.1, total volume, and max. 3D diameter. The changes in parameters were calculated for each patient after immunotherapy. The ROC curve was used to analyze the sensitivity and specificity of the size change of the legion. This was useful to find new volumetric thresholds with better efficiency in response assessment. The changes in total volume were assessed by conventional volumetric thresholds, while RECIST 1.1 thresholds were for the max. 3D diameter. A chi-square test was used to compare the concordance and diagnostic correlation between the response assessment results of the three criteria.ResultsA total of 20 cases (average age, 58 years; range, 23 to 84 years) and 58 follow-up MR examinations after immunotherapy were included in the analysis. The P-value of the chi-square test between RECIST 1.1 and total volume is 0 (P <0.05), same as that in RECIST 1.1 and max. 3D diameter. The kappa value of the former two was 0.775, and the kappa value for the latter two was 0.742. The above results indicate a significant correlation and good concordance for all three criteria. In addition, we also found that the volumetric assessment had the best sensitivity and specificity for the immunotherapy response in intracranial malignancies, with a PR threshold of −64.9% and a PD threshold of 21.4%.ConclusionsRadiologic assessment of immunotherapy response in intracranial malignancy can be performed by multiple criteria based on semi-automatic segmentation technique on MR images, such as total volume, max. 3D diameter and RECIST 1.1. In addition, new volumetric thresholds with good sensitivity and specificity were found by volumetric assessment

Deciphering the Spatial Arrangement of Metals and Correlation to Reactivity in Multivariate Metal–Organic Frameworks

Thirty-six porphyrin-based metal–organic frameworks (MOFs) with composition of <b>(M</b>_<b>3</b><b>O)</b>_<b>2</b><b>(TCPP-M)</b>_<b>3</b> and M₃O trigonal SBUs of various metals, Mg₃O, Mn₃O, Co₃O, Ni₃O, and Fe₃O including mixed-metal SBUs, Mn_<i>x</i>Fe_3–<i>x</i>O, Ni_<i>x</i>Fe_3–<i>x</i>O, Co_<i>x</i>Ni_3–<i>x</i>O, Mn_<i>x</i>Co_3–<i>x</i>O, Mn_<i>x</i>Mg_3–<i>x</i>O, and Mn_<i>x</i>Ni_3–<i>x</i>O were synthesized and characterized. These multivariate MOFs (MTV-MOFs) were examined by X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectra, and for the first time, their metal spatial arrangement deciphered and were found to exist in the form of either domains or well-mixed. We find that MTV-MOFs with well-mixed metals in their SBUs, rather than the SBUs having one kind of metal but different from one SBU to another, perform better than the sum of their parts in the test reaction involving the photo-oxidation of 1,5-dihydroxynaphthalene

Structural Derivative and Electronic Property of Armchair Carbon Nanotubes from Carbon Clusters

The structural derivative and electronic property of carbon nanotubes from carbon clusters were investigated by density functional theory (DFT), including armchair single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs). Results show that the carbon nanotubes (CNTs) can be obtained through layer-by-layer growth from the initial structure. The structural derivative processes are quantitatively described by monitoring changes in local configuration. Electronic properties show the energy gaps of finite SWCNTs and double-walled CNTs (DWCNTs) depending on their lengths. However, the band structures of MWCNTs differ from those of SWCNTs; the band structures of DWCNTs (4, 4)@(8, 8), (5, 5)@(10, 10), and TWCNTs show metallicity, whereas those of (3, 3)@(6, 6) DWCNTs show a strong semiconductor characteristic. Analysis of the partial density of states shows that the diameters and walls of CNTs have no obvious effects on the distribution of total density of states near the Fermi level of SWCNTs and MWCNTs

Room-Temperature Ordered Spin Structures in Cluster-Assembled Single V@Si₁₂ Sheets

Since most of the existing pristine two-dimensional (2D) materials are either intrinsically nonmagnetic or magnetic with small magnetic moment per unit cell and weak strength of magnetic coupling, introducing transition metal atoms in various nanosheets has been widely used for achieving a desired 2D magnetic material. However, the problem of surface clustering for the doped transition metal atoms is still challenging. Here we demonstrate via first-principles calculations that the recently experimentally characterized endohedral silicon cage V@Si₁₂ clusters can construct two types of single cluster sheets exhibiting hexagonal porous or honeycomb-like framework with regularly and separately distributed V atoms. For the ground state of these two sheets, the preferred magnetic coupling is found to be ferromagnetic due to a free-electron-mediated mechanism. By using external strain, the magnetic moments and strength of magnetic coupling for these two sheets can be deliberately tuned, which would be propitious to their advanced applications. More attractively, our first-principles molecular dynamics simulations show that both the structure and strength of ferromagnetic coupling for the pristine porous sheet are stable enough to survive at room temperature. The insights obtained in this work highlight a new avenue to achieve 2D silicon-based spintronics nanomaterials

Silver(I)-Catalyzed Atroposelective Desymmetrization of <i>N</i>‑Arylmaleimide via 1,3-Dipolar Cycloaddition of Azomethine Ylides: Access to Octahydropyrrolo[3,4‑<i>c</i>]pyrrole Derivatives

A highly efficient Ag­(I)-catalyzed atroposelective desymmetrization of <i>N</i>-(2-<i>t</i>-butylphenyl)­maleimide via 1,3-dipolar cycloaddition of in situ generated azomethine ylides has been established successfully, affording a facile access to a series of biologically important and enantioenriched octahydropyrrolo­[3,4-<i>c</i>]­pyrrole derivatives in generally high yields (up to 99%) with excellent levels of diastereo-/enantioselectivities (up to 99% ee, >20:1 dr). Subsequent transformations led to fascinating 2<i>H</i>-pyrrole and polysubstituted pyrrole compounds without loss of stereoselectivity. The absolute configuration of the generated chiral axis has been unambiguously identified as (<i>M</i>) through single-crystal X-ray diffraction analysis. Furthermore, on the basis of the comprehensive experimental results and the absolute configuration of one of the cycloadducts, the origin of the stereoselectivity was proposed to be attributed to the steric congestion imposed by the bulky PPh₂ group of the chiral ligand and the <i>tert</i>-butyl group of <i>N</i>-(2-<i>t</i>-butylphenyl)­maleimide. The possible hydrogen bond interaction between the NH₂ group of the chiral ligand and one of the carbonyl groups of <i>N</i>-(2-<i>t</i>-butylphenyl)­maleimide is considered to facilitate stabilizing the transition state

From the ZnO Hollow Cage Clusters to ZnO Nanoporous Phases: A First-Principles Bottom-Up Prediction

A family of Zn_<i>k</i>O_<i>k</i> (<i>k</i> = 12, 16) cluster-assembled solid phases with novel structures and properties has been characterized utilizing a bottom-up approach with density functional calculations. Geometries, stabilities, equation of states, phase transitions, and electronic properties of these ZnO polymorphs have been systematically investigated. First-principles molecular dynamics (FPMD) study of the two selected building blocks, Zn₁₂O₁₂ and Zn₁₆O₁₆, with hollow cage structure and large HOMO–LUMO gap shows that both of them are thermodynamically stable enough to survive up to at least 500 K. Via the coalescence of building blocks, we find that the Zn₁₂O₁₂ cages are able to form eight stable phases by four types of Zn₁₂O₁₂–Zn₁₂O₁₂ interactions, and the Zn₁₆O₁₆ cages can bind into three phases by the Zn₁₆O₁₆–Zn₁₆O₁₆ links of H′, C′, and S′. Among these phases, six ones are reported for the first time. This has greatly extended the family of ZnO nanoporous phases. Notably, some of these phases are even more stable than the synthesized metastable rocksalt ZnO polymorph. The hollow cage structure of the corresponding building block Zn_<i>k</i>O_<i>k</i> is well preserved in all of them, which leads to their low-density nanoporous and high flexibility features. In addition the electronic integrity (wide-energy gap) of the individual Zn_<i>k</i>O_<i>k</i> is also retained. Our calculation reveals that they are all semiconductor with a large direct or indirect band gap. The insights obtained in this work are likely to be general in II–VI semiconductor compounds and will be helpful for extending the range of properties and applications of ZnO materials