NEMA NU 2-2018 performance evaluation of a new generation 30-cm axial field-of-view Discovery MI PET/CT.

PURPOSE: The DMI PET/CT is a modular silicon photomultiplier-based scanner with an axial field-of-view (FOV) between 15 and 25 cm depending on ring configuration (3, 4, or 5 rings). A new generation of the system includes a reengineered detector module, featuring improved electronics and an additional 6th ring, extending the axial FOV to 30 cm. We report on the performance evaluation of the 6-ring upgraded Generation 2 (Gen2) system while values are also reported for the 5-ring configuration of the very same system prior to the upgrade. METHODS: PET performance was evaluated using the NEMA NU 2-2018 standard for spatial resolution, sensitivity, image quality, count rate performance, timing resolution, and image co-registration accuracy. Patient images were used to assess image quality. RESULTS: The average system sensitivity was measured at 32.76 cps/kBq (~ 47% increase to 5 rings at 22.29 cps/kBq) while noise equivalent count rate peaked at 434.3 kcps corresponding to 23.6 kBq/mL (~ 60% increase to Generation 1 (Gen1) and 39% to Gen2 5 rings). Contrast recovery ranged between 54.5 and 85.8% similar to 5 rings, while the 6 rings provided lower background variability (2.3-8.5% for 5 rings vs 1.9-6.8% for 6 rings) and lower lung error (4.0% for the 5 rings and 3.16% for the 6 rings). Transverse/axial full width at half-maximum (FWHM) at 1 cm (3.79/4.26 mm) and 10 cm (4.29/4.55 mm), scatter fraction (40.2%), energy resolution (9.63%), and time-of-flight (TOF) resolution (389.6 ps at 0 kBq/mL) were in line to previously reported values measured across different system configurations. Improved patient image quality is obtained with the 6 rings compared to the 5 rings, while image quality is retained even at reduced scan times, enabling WB dynamic acquisitions. CONCLUSIONS: The higher sensitivity of the 6-ring DMI compared to the 5-ring configuration may lead to improved image quality of clinical images at reduced scan time. Additionally, it could equally be used to allow improved temporal sampling and/or reduced overall scan time in dynamic acquisitions. Conversely, temporal sampling and scan time could be traded per application to further drive injected dose at lower levels.

New Diterpenes with a Fused 6-5-6-6 Ring System Isolated from the Marine Sponge-Derived Fungus Trichoderma harzianum.

New diterpenes, namely, trichodermanins F-H, with a fused 6-5-6-6 ring system were isolated from the fungus Trichoderma harzianum OUPS-111D-4 separated from a marine sponge Halichondria okadai. These chemical structures were elucidated by 1D and 2D NMR as well as high-resolution fast atom bombardment mass spectrometry (HRFABMS) spectral analyses. We established their absolute stereostructures by application of the modified Mosher's method or circular dichroism (CD) spectroscopy. In addition, their cytotoxicities were assessed using several cancer cell lines, with 1 and 2 exhibiting modest activities.

Trichodermanins C-E, New Diterpenes with a Fused 6-5-6-6 Ring System Produced by a Marine Sponge-Derived Fungus.

Trichodermanins C-E (1-3), new diterpenes with a rare fused 6-5-6-6 ring system, have been isolated from a fungus Trichoderma harzianum OUPS-111D-4 separated from a piece of a marine sponge Halichondria okadai, and these chemical structures have been established by spectroscopic analyses using IR, MASS, HRFABMS, and NMR spectra. We established their absolute stereostructures by application of the modified Mosher's method. In addition, 1 inhibited the growth of cancer cell lines potently.

Hexagonal bipyramidal [Ta(2)B(6)](-/0) clusters: B(6) rings as structural motifs.

It has been a long-sought goal in cluster science to discover stable atomic clusters as building blocks for cluster-assembled nanomaterials, as exemplified by the fullerenes and their subsequent bulk syntheses.1, 2 Clusters have also been considered as models to understand bulk properties, providing a bridge between molecular and solid-state chemistry.3 Because of its electron deficiency, boron is an interesting element with unusual polymorphism. While bulk boron is known to be dominated by the three-dimensional (3D) B12 icosahedral motifs,4 new forms of elemental boron are continuing to be discovered.5 In contrast to the 3D cages commonly found in bulk boron, in the gas phase two-dimensional (2D) boron clusters are prevalent.6-8 The unusual planar boron clusters have been suggested as potential new bulking blocks or ligands in chemistry.6a Herein we report a joint experimental and theoretical study on the [Ta2 B6 ](-) and [Ta2 B6 ] clusters. We found that the most stable structures of both the neutral and anion are D6h bipyramidal, similar to the recently discovered MB6 M structural motif in the Ti7 Rh4 Ir2 B8 solid compound.9.

Mosaic ring chromosome 6 in an infant with significant patent ductus arteriosus and multiple congenital anomalies.

The clinical features of ring chromosome 6 include central nervous system anomalies, growth retardation, facial dysmorphism and other congenital anomalies. Ring chromosome 6 occurs rarely and manifests as various phenotypes. We report the case of mosaic ring chromosome 6 by conventional karyotyping in a 7-day-old male infant diagnosed with a large patent ductus arteriosus (PDA) with hypoplasia of aortic valve and aortic arch. These have not been previously reported with ring chromosome 6. He recovered from heart failure symptoms after ligation of the PDA. He showed infantile failure to thrive and delayed milestone in a follow-up evaluation. To the best of our knowledge, this is the first report of a Korean individual with ring chromosome 6 and hemodynamically significant PDA.

Combined fluorescent measurements, parallel factor analysis and GC-mass spectrometry in evaluating the photodegradation of PAHS in freshwater systems.

To better understand the transformation and photochemical fate of PAHs in aquatic environments, a custom-designed closed-circuit recirculation photodegradation system, combined with inline semi-continuous fluorescence and absorbance measurements, as well as modelling of excitation-emission (EEM) measurements with parallel factor analysis (PARAFAC), and GC-MS analysis, were combined to create a robust tool for holistically assessing the photodegradation of individual PAHs, their mixtures and photoproduct formation. Selected compounds included in the US EPA priority list, representing 2- to 6-ring compounds, were monitored individually and in mixtures, during 24 h photodegradation experiments. Experiments were conducted in solutions simulating ideal (ultrapure water) and environmentally relevant conditions (1.00 mg L-1 Suwannee River Natural Organic Matter (SRNOM)). The fluorescence, primary PARAFAC components and quantification data obtained by GC-MS, indicated that the decline in parent molecule concentration occurred rapidly within 200 min. The degradation rates of parent PAHs increased with aromaticity (6-ring ≫ 2-ring PAHs) and followed pseudo-first order degradation kinetics. The presence and transformation of degradation products, were captured by PARAFAC. NOM influenced the diversity of photoproducts. From the GC-MS results, photoproducts were only detected in Ant, BAnt and the PAH mixture solutions, but optical property analyses indicated that diverse changes occurred with all PAHs. Spectrometric and chromatographic data demonstrated that parent PAHs and photoproducts co-existed at various stages, which is significant for freshwater systems contaminated with these compounds if photoproducts have higher-toxic potential. These results may be used to model the hazard-potential associated with PAHs present in freshwater systems and understanding the mechanisms that govern their environmental fate.

An Ordered Ni6 -Ring Superstructure Enables a Highly Stable Sodium Oxide Cathode.

Sodium-based layered oxides are among the leading cathode candidates for sodium-ion batteries, toward potential grid energy storage, having large specific capacity, good ionic conductivity, and feasible synthesis. Despite their excellent prospects, the performance of layered intercalation materials is affected by both a phase transition induced by the gliding of the transition metal slabs and air-exposure degradation within the Na layers. Here, this problem is significantly mitigated by selecting two ions with very different MO bond energies to construct a highly ordered Ni6 -ring superstructure within the transition metal layers in a model compound (NaNi2/3 Sb1/3 O2 ). By virtue of substitution of 1/3 nickel with antimony in NaNiO2 , the existence of these ordered Ni6 -rings with super-exchange interaction to form a symmetric atomic configuration and degenerate electronic orbital in layered oxides can not only largely enhance their air stability and thermal stability, but also increase the redox potential and simplify the phase-transition process during battery cycling. The findings reveal that the ordered Ni6 -ring superstructure is beneficial for constructing highly stable layered cathodes and calls for new paradigms for better design of layered materials.

A structural study of Si6-ring-containing [Si6Cl14](2-) chlorosilicates.

The crystal structures of four substituted-ammonium dichloride dodecachlorohexasilanes are presented. Each is crystallized with a different cation and one of the structures contains a benzene solvent molecule: bis(tetraethylammonium) dichloride dodecachlorohexasilane, 2C8H20N(+)·2Cl(-)·Cl12Si6, (I), tetrabutylammonium tributylmethylammonium dichloride dodecachlorohexasilane, C16H36N(+)·C13H30N(+)·2Cl(-)·Cl12Si6, (II), bis(tetrabutylammonium) dichloride dodecachlorohexasilane benzene disolvate, 2C16H36N(+)·2Cl(-)·Cl12Si6·2C6H6, (III), and bis(benzyltriphenylphosphonium) dichloride dodecachlorohexasilane, 2C25H22P(+)·2Cl(-)·Cl12Si6, (IV). In all four structures, the dodecachlorohexasilane ring is located on a crystallographic centre of inversion. The geometry of the dichloride dodecachlorohexasilanes in the different structures is almost the same, irrespective of the cocrystallized cation and solvent. However, the crystal structure of the parent dodecachlorohexasilane molecule shows that this molecule adopts a chair conformation. In (IV), the P atom and the benzyl group of the cation are disordered over two sites, with a site-occupation factor of 0.560 (5) for the major-occupied site.

Crystal structure of (E)-1-(1-hy-droxy-naphthalen-2-yl)-3-(2,3,4-tri-meth-oxy-phen-yl)prop-2-en-1-one.

The title compound, C22H20O5, is composed of a hy-droxy-naphthyl ring and a tri-meth-oxy-phenyl ring [the planes of which are inclined to one another by 21.61 (10)°] bridged by an unsaturated prop-2-en-1-one group. The mean plane of the prop-2-en-1-one group [-C(=O)-C=C-] is inclined to that of the naphthyl system and benzene rings by 3.77 (14) and 18.01 (16)°, respectively. There is an intra-molecular O-H⋯O hydrogen bond present forming an S(6) ring motif. In the crystal, inversion-related mol-ecules are linked by a slipped-parallel π-π inter-action [inter-centroid distance = 3.8942 (13) Å, inter-planar distance = 3.478 (9) Šand slippage = 1.751 Å], and stack along the [101] direction. There are no other significant inter-molecular inter-actions present.

Mosaic Ring Chromosome 6 in an Infant with Significant Patent Ductus Arteriosus and Multiple Congenital Anomalies

The clinical features of ring chromosome 6 include central nervous system anomalies, growth retardation, facial dysmorphism and other congenital anomalies. Ring chromosome 6 occurs rarely and manifests as various phenotypes. We report the case of mosaic ring chromosome 6 by conventional karyotyping in a 7-day-old male infant diagnosed with a large patent ductus arteriosus (PDA) with hypoplasia of aortic valve and aortic arch. These have not been previously reported with ring chromosome 6. He recovered from heart failure symptoms after ligation of the PDA. He showed infantile failure to thrive and delayed milestone in a follow-up evaluation. To the best of our knowledge, this is the first report of a Korean individual with ring chromosome 6 and hemodynamically significant PDA.