The shielding cone concept is one of the most characteristic aspects of planar aromatic species. Herein, we explored how two neighbor aromatic moieties behave as dual planar‐planar, planar‐spherical, ...and spherical‐spherical species given by biphenyl, PhCB11H11−, and CB11H1122−, respectively. Our results show two separate aromatic regimes given by Clar's sextet and spherical aromatic states, with independent shielding cones sharing shielding regions of moderate strength, which can be extended for networks involving multiple independent aromatic states.
From flatland to space! Dual planar‐planar, planar‐spherical, and spherical‐spherical species given by biphenyl, PhCB11H11−, and CB11H1122−, respectively shows two separate aromatic regimes given by Clar's sextet and spherical aromatic states, with independent shielding cones sharing shielding regions of moderate strength.
IMPORTANCE: Pelvic floor disorders (eg, urinary incontinence), which affect approximately 25% of women in the United States, are associated with childbirth. However, little is known about the course ...and progression of pelvic floor disorders over time. OBJECTIVE: To describe the incidence of pelvic floor disorders after childbirth and identify maternal and obstetrical characteristics associated with patterns of incidence 1 to 2 decades after delivery. DESIGN, SETTING, AND PARTICIPANTS: Women were recruited from a community hospital for this cohort study 5 to 10 years after their first delivery and followed up annually for up to 9 years. Recruitment was based on mode of delivery; delivery groups were matched for age and years since first delivery. Of 4072 eligible women, 1528 enrolled between October 2008 and December 2013. Annual follow-up continued through April 2017. EXPOSURES: Participants were categorized into the following mode of delivery groups: cesarean birth (cesarean deliveries only), spontaneous vaginal birth (≥1 spontaneous vaginal delivery and no operative vaginal deliveries), or operative vaginal birth (≥1 operative vaginal delivery). MAIN OUTCOMES AND MEASURES: Stress urinary incontinence (SUI), overactive bladder (OAB), and anal incontinence (AI), defined using validated threshold scores from the Epidemiology of Prolapse and Incontinence Questionnaire, and pelvic organ prolapse (POP), measured using the Pelvic Organ Prolapse Quantification Examination. Cumulative incidences, by delivery group, were estimated using parametric methods. Hazard ratios, by exposure, were estimated using semiparametric models. RESULTS: Among 1528 women (778 in the cesarean birth group, 565 in the spontaneous vaginal birth group, and 185 in the operative vaginal birth group), the median age at first delivery was 30.6 years, 1092 women (72%) were multiparous at enrollment (2887 total deliveries), and the median age at enrollment was 38.3 years. During a median follow-up of 5.1 years (7804 person-visits), there were 138 cases of SUI, 117 cases of OAB, 168 cases of AI, and 153 cases of POP. For spontaneous vaginal delivery (reference), the 15-year cumulative incidences of pelvic floor disorders after first delivery were as follows: SUI, 34.3% (95% CI, 29.9%-38.6%); OAB, 21.8% (95% CI, 17.8%-25.7%); AI, 30.6% (95% CI, 26.4%-34.9%), and POP, 30.0% (95% CI, 25.1%-34.9%). Compared with spontaneous vaginal delivery, cesarean delivery was associated with significantly lower hazard of SUI (adjusted hazard ratio aHR, 0.46 95% CI, 0.32-0.67), OAB (aHR, 0.51 95% CI, 0.34-0.76), and POP (aHR, 0.28 95% CI, 0.19-0.42), while operative vaginal delivery was associated with significantly higher hazard of AI (aHR, 1.75 95% CI, 1.14-2.68) and POP (aHR, 1.88 95% CI, 1.28-2.78). Stratifying by delivery mode, the hazard ratios for POP, relative to a genital hiatus size less than or equal to 2.5 cm, were 3.0 (95% CI, 1.7-5.3) for a genital hiatus size of 3 cm and 9.0 (95% CI, 5.5-14.8) for a genital hiatus size greater than or equal to 3.5 cm. CONCLUSIONS AND RELEVANCE: Compared with spontaneous vaginal delivery, cesarean delivery was associated with significantly lower hazard for stress urinary incontinence, overactive bladder, and pelvic organ prolapse, while operative vaginal delivery was associated with significantly higher hazard of anal incontinence and pelvic organ prolapse. A larger genital hiatus was associated with increased risk of pelvic organ prolapse independent of delivery mode.
The induced magnetic field of C
2
N
(
N
= 3-14) carbon rings was dissected to contributions from out-of-plane and in-plane π orbitals revealing two concurrent long range shielding or deshielding ...cones as a manifestation of the dual aromatic and antiaromatic character of C
4
n
+2
and of C
4
n
rings respectively. Aromaticity based on the magnetic criterion was evaluated with regard to the bonding pattern and geometrical characteristics that elucidate the influence of bond length and bond angle alteration on out-of-plane and in-plane magnetic responses. Ground state polyynic geometries of C
4
n
+2
rings exhibit comparable shielding cones to annulenes, decreasing the magnetic response with regard to the ring size and similar π
out
and π
in
diatropicity. Transition state cumulenic rings display increased aromaticity expressed by a very strong constant magnetic response and augmented π
out
diatropicity with regard to π
in
. The variations of the induced magnetic field are explained on the basis of frontier orbital interactions through rotational excitations, which enable further rationalization of the aromatic/antiaromatic behavior.
Two orthogonal sets of π orbitals induce concurrent (de)shielding cones demonstrating the double (anti)aromaticity of sp-hybridized carbon rings.
A unique four‐coordinate, classical gold(I)‐carbonyl complex with substantial backdonation from gold has been isolated by using a B‐methylated and fluorinated tris(pyridyl)borate chelator. Its ...lighter silver(I) and copper(I) analogs enabled a study of trends in the coinage‐metal family. The B‐arylated ligand version also afforded a gold–carbon monoxide complex that displays a notably low C−O stretch value, but with trigonal planar geometry at the gold. A computational analysis shows that the AuI−CO bonds of these tris(pyridyl)borate ligand‐supported molecules consist of electrostatic attraction, OC→Au σ‐donation, and very significant Au→CO π‐back‐bonding components. The latter is responsible for the observed C−O stretching frequencies, which are lower than in free CO.
Pyridyl‐borate scorpionates decorated with anionic and fluoro‐alkyl groups serve as ideal ligands to capture gold(I)‐carbon monoxide fragments in trigonal planar and tetrahedral environments that display remarkably low C−O stretching frequencies, and have significant Au−CO π‐bond character.
The characterized phenyl decorated closo-monocarboranes with variable sizes from 7- to 12-vertex cages, Ph-closo-CB n H n −, n = 6–11, allow us to address the role of the varying size and shape of ...the carborane cage in dual planar–spherical aromatic species. Our results show the formation of adjacent shielding cone characteristics enabled from both planar and spherical aromatic fragments, despite the different structures of the closo-monocarboranes. Under a field perpendicular to the phenyl ring, both shielding cones are enabled, which overlap at long-range regions, in contrast to other orientations leading to a short-range response from the planar aromatic fragment. Thus, a two- or one-aromatic circuit is enabled selectively within the same molecular unit, by controlling the orientation of the external field. Along with the series, a variable extension of the shielding cone from the carborane cage is observed, which is larger for the −CB11H11 case, decreasing toward −CB6H6, denoting a similar extension from both the planar and spherical aromatic regions at the 4-Ph-closo-4-CB8H8− (4) counterpart. The analysis of such multiple aromatic structures shows that, despite the different sizes and shapes of the closo cages, a similar aromatic behavior remains. In addition, the anisotropy of the induced magnetic field is given graphically, denoting a larger anisotropy for the planar aromatic moiety owing to its two-dimensional structure, which is suggested to discriminate between planar and spherical aromatic fragments within the same molecule.
Background Few studies have prospectively evaluated the progression of chronic kidney disease (CKD) in children and adolescents, as well as factors associated with progression. Study Design ...Prospective multicenter observational cohort study. Setting & Participants 496 children and adolescents with CKD enrolled in the Chronic Kidney Disease in Children (CKiD) Study. Predictors Proteinuria, hypoalbuminemia, blood pressure, dyslipidemia, and anemia. Outcomes Parametric failure-time models were used to characterize adjusted associations between baseline levels and changes in predictors and time to a composite event of renal replacement therapy or 50% decline in glomerular filtration rate (GFR). Results 398 patients had nonglomerular disease and 98 had glomerular disease; of these, 29% and 41%, respectively, progressed to the composite event after median follow-ups of 5.2 and 3.7 years, respectively. Demographic and clinical characteristics and outcomes differed substantially according to the underlying diagnosis; hence, risk factors for progression were assessed in stratified analyses, and formal interactions by diagnosis were performed. Among patients with nonglomerular disease and after adjusting for baseline GFR, times to the composite event were significantly shorter with urinary protein-creatinine ratio > 2 mg/mg, hypoalbuminemia, elevated blood pressure, dyslipidemia, male sex, and anemia, by 79%, 69%, 38%, 40%, 38%, and 45%, respectively. Among patients with glomerular disease, urinary protein-creatinine ratio >2 mg/mg, hypoalbuminemia, and elevated blood pressure were associated with significantly reduced times to the composite event by 94%, 71%, and 67%, respectively. Variables expressing change in patient clinical status over the initial year of the study contributed significantly to the model, which was cross-validated internally. Limitations Small number of events in glomerular patients and use of internal cross-validation. Conclusions Characterization and modeling of risk factors for CKD progression can be used to predict the extent to which these factors, either alone or in combination, would shorten the time to renal replacement therapy or 50% decline in GFR in children with CKD.
Structural characterization of the discrete Sn@Cu12@Sn2012− cluster exposed a fascinating architecture composed of three concentric structural layers in which an endohedral Sn atom is enclosed in a ...Cu12 icosahedron, which in turn is embedded in an Sn20 dodecahedron. Herein, the possibility of sustaining aromatic behavior for this prototypical multilayered species was evaluated, in order to extend this concept to more complex clusters on the basis of magnetic response and bonding analysis by the AdNDP approach. This revealed characteristic features of spherical aromatics, given by the ability to sustain the shielding cone property, similar to archetypal aromatics. The favorable bonding pattern in the Sn@Cu12@Sn2012− cluster fulfills the 2(N+1)2 Hirsch rule for aromaticity; thus, the cluster could be regarded as a first member of aromatic multilayered structures. The set of four 13c–2e aromatic bonds that was identified in the internal SnCu12 structure results in spherical aromatic character of this multilayered cluster. This insight builds a bridge between the traditional concept of Hückel's aromaticity and the aromaticity of complex and stable 3D systems that may be explored on the basis of magnetic response and bonding analysis. It also may open a way to novel findings in bottled clusters displaying aromatic behavior in multilayer structures, which are of great interest for inorganic nano‐ and material sciences due to their unprecedented stability.
Russian doll aromatic: The Sn@Cu12@Sn2012− cluster, in which an endohedral Sn atom is enclosed in a Cu12 icosahedron, which in turn is embedded in an Sn20 dodecahedron, was shown by theoretical calculations to exhibit spherical aromaticity. Its shielding cone, which remains parallel to applied fields aligned in different orientations, resembles that of the classical planar aromatic compound benzene (see figure).
Dications of cycloparaphenyles (nCPPs) are known to exhibit in‐plane global aromaticity, contained in a nanobelt structure. Recently synthesized ortho and meta isomers of nCPPs break the radial ...symmetry of π structure incorporating perpendicular oriented π orbitals. Herein we set to explore the aromaticity of neutral and dicationic ortho and meta isomers of 8CPP by dissecting the induced magnetic field to contributions of the twofold radial/perpendicular π system using delocalized canonical molecular orbitals (CMO), and introducing the natural localized molecular orbitals (NLMO) analysis with DFT methods. The dications sustain a reduced global aromatic character of the radial π system under a perpendicular orientation of the external field which declines from ortho to meta isomer and reinforces local aromaticity of ortho ring while it destroys aromaticity of meta ring. Aromaticity variations are determined by symmetry governed rotational excitations of frontier π orbitals. The parallel orientation reveals a substantial reduction of local aromaticity verified with NICSπ analysis and electron delocalization indices.
How aromatic? Ortho and meta isomers of the 8‐clycloparaphenylene dication retain a decreasing global aromatic character of the twofold radial‐perpendicular π system, while local aromaticity is augmented in the ortho ring and becomes antiaromatic in meta ring.
Ligand‐protected gold clusters are usually understood in terms of the superatom concept, where certain species are able to behaves as prototypical molecules. Here, we discuss the metalloid cluster ...Au70S20(PPh3)12 in terms of the bonding characteristics of its inner 18‐cluster electron Au224+ core. Our interpretation is based on a SP3‐hybridized core involving four fused Au6 units denoting four equivalent hybridized localized orbitals, with the remaining electrons from the 1D10 state remaining as formally non‐bonding orbitals. Such characteristics expose a rationalization of Au70S20(PPh3)1 as a superatomic analog for a transition metal complex, following the 18‐electron rule, mimicking the classical bonding picture of the tetrahedral Ni(CO)4 complex. The Au22 core as an aggregate of Au6 units encourages the search for further examples of SP3‐cluster nodes precluding larger aggregates, contributing to the design opportunities of functional clusters and nanoparticles.
Background
Assessing bias (estimated – measured) is key to evaluating glomerular filtration rate (GFR). Stratification by subgroups can indicate where equations perform differently. However, there is ...a fallacy in the assessment of two instruments (e.g., eGFR and mGFR) when stratifying on the level of only one of those instruments. Here, we present statistical aspects of the problem and a solution for GFR stratification along with an empirical investigation using data from the CKiD study.
Methods
Compared and contrasted biases (eGFR relative to mGFR) with 95% confidence intervals within strata of mGFR only, eGFR only, and the average of mGFR and eGFR using data from the Chronic Kidney Disease in Children (CKiD) study.
Results
A total of 304 participants contributed 843 GFR studies with a mean mGFR of 48.46 (SD = 22.72) and mean eGFR of 48.67 (SD = 22.32) and correlation of 0.904. Despite strong agreement, eGFR significantly overestimated mGFR when mGFR < 30 (+ 6.2%; 95%CI + 2.9%, + 9.7%) and significantly underestimated when mGFR > 90 (–12.2%; 95%CI − 17.3%, − 7.0%). Significant biases in opposite direction were present when stratifying by eGFR only. In contrast, when stratifying by the average of eGFR and mGFR, biases were not significant (+ 1.3% and − 1.0%, respectively) congruent with strong agreement.
Conclusions
Stratifying by either mGFR or eGFR only to assess eGFR biases is ubiquitous but can lead to inappropriate inference due to intrinsic statistical issues that we characterize and empirically illustrate using data from the CKiD study. Using the average of eGFR and mGFR is recommended for valid inferences in evaluations of eGFR biases.
Graphical Abstract
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