Using data (2655 observations from 928 participants) from the Chronic Kidney Disease in Children Study, we developed and internally validated new glomerular filtration rate estimating equations for ...clinical use in children and young adults: two forms of K × heigh(ht) / serum creatinine(sCr) and two forms of K × 1 / cystatin C(cysC). For each marker, one equation used a sex-dependent K; in the other, K is sex-and age-dependent. Glomerular filtration rate (GFR) was measured directly by plasma iohexol disappearance. The equations using ht⁄sCr had sex-specific constants of 41.8 for males and 37.6 for females. In the age- dependent models, K increased monotonically for children 1-18 years old and was constant for young adults 18-25 years. For males, K ranged from 35.7 for one-year-olds to 50.8 for those 18 and older. For females, the values of K ranged from 33.1 to 41.4. Constant K values for cystatin-C equations were 81.9 for males and 74.9 for females. With age-dependency, K varied non-monotonically with the highest values at age 15 for males (K of 87.2) and 12 years for females (K of 79.9). Use of an age-dependent K with ht/sCr models reduced average bias, notably in young children and young adults; age-dependent cystatin-C models produced similar agreement to using a constant K in children under 18 years, but reduced bias in young adults. These age-dependent proposed equations were evaluated alongside estimated GFRs from 11 other published equations for pediatrics and young adults. Only our proposed equations yielded non- significant bias and within 30% accuracy values greater than 85% in both the pediatric and young adult subpopulations.
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Sterically loaded, anionic pyridine has been synthesized and utilized successfully in the stabilization of a homoleptic series of coinage metal complexes. The treatment of 4-(Ph3B)-2,6-Trip2PyK ...(Trip =2,4,6-iPr3C6H2) with CuBr(PPh3), AgCl(PPh3) or AuCl(PPh3) (Py = pyridine) afforded the corresponding 4-(Ph3B)-2,6-Trip2PyM(PPh3) (M = Au, Ag, Cu) complexes, via salt metathesis, as isolable, crystalline solids. Notably, these reactions avoid the facile single electron transfer chemistry reported with the less bulky ligand systems. The X-ray structures revealed that they are two-coordinate metal adducts. The M-N and M-P bond distances are longest in the silver and shortest in the copper adduct among the three group 11 family members. Computational analysis revealed an interesting stability dependence on steric bulk of the anionic pyridine (i.e., pyridyl borate) ligand. A comparison of structures and bonding of 4-(Ph3B)-2,6-Trip2PyAu(PPh3) to pyridine and m-terphenyl complexes, {2,6-Trip2PyAu(PPh3)}SbF6 and 2,6-Trip2PhAu(PPh3) are also provided. The Au(I) isocyanide complex, 4-(Ph3B)-2,6-Trip2PyAu(CNBut) has been stabilized using the same anionic pyridylborate illustrating that it can support other gold-ligand moieties as well.
Gold clusters are useful templates for nanosized species retaining a distinctive size-dependent behavior. Usually, a ligand-protected shell passivates such clusters, where their properties can be ...potentially tuned by introduction of versatile ligands. Here, we explored the recent addition to the well-explored gold–phosphine chemistry, introducing N-heterocyclic carbine (NHC) ligands as characterized by the octahedral carbon-centered CAu6 core, in CAu6(NHC)62+. Our results show their similar bonding patterns in such discrete clusters, with slight preference for the later ligands, enabling the proposition of medium-sized species featuring the predominant icosahedral Au13 structure. NHC counterparts for Au13Cl2(dppe) and Au25Cl2(PPh3)10(SR)5 clusters, denoting both icosahedral and bi-icosahedral central cores, where the bonding features patterns and favorable stability, remain similar to that observed for their phosphine parents and CAu6(NHC)62+ clusters, shedding light on other feasible members for explorative synthetic efforts. Optical properties are modified when NHC is introduced instead of phosphine ligands, inducing a red-shift for the lowest-energy peak with a highest occupied molecular orbital lowest unoccupied molecular orbital character and a blue-shift for higher energy absorptions. Hence, NHC derivatives as a ligand-protected layer for medium-sized clusters can introduce useful alternatives for ligand-protected shells, which can be further explored owing to their recognition for well-established versatility in organometallic chemistry.
The title compound, which has a ten‐atom deltahedral cluster core of Ge9Pd, was synthesized through insertion of Pd(PPh3) into the tetrasubstituted nona‐germanium cluster (Me3Si)Si3EtGe9 through a ...reaction of the latter with Pd(PPh3)4. This first reaction of neutral tetrasubstituted nine‐atom clusters shows that they retain reactivity despite their neutral charge. The Ge9Pd core is the first that incorporates a 5‐connected transition metal other than from Group VI, a noble metal in this case. Single‐crystal X‐ray diffraction shows that the ten‐atom core is a closo‐cluster with the expected shape of a bicapped square antiprism. 1H and 13C NMR spectroscopy show that, in contrast to the parent tetra‐substituted (Me3Si)Si3EtGe9, the new compound does not exhibit dynamics. Relativistic DFT calculations are used to explain the differences.
Cage closed: The title compound, an uncharged single‐cage deltahedron with five functionalities, was synthesized through insertion of Pd(PPh3) into (Me3Si)Si3EtGe9. The ten‐atom core is a closo‐cluster with the expected shape of a bicapped square antiprism, and the Ge9Pd core is the first to incorporates a 5‐connected transition metal other than from Group VI. In contrast to the Pd‐free parent, the new compound is static in solution.
The isolated‐pentagon rule (IPR) is a determining structural feature that accounts for hollow fullerene stabilization and properties related to Cn (n≥60) cages. The recent characterization of an ...unprecedented non‐IPR hydrofullerene, C2v C66H4, bearing two heptagons with adjacent fused‐pentagon motifs, largely dismisses this feature. Herein, employing DFT calculations, the 13C NMR spectroscopy and aromatic behavior of C2v C66H4 are explored. The results show the presence of three π‐aromatic circuits at the bottom boat section of C66H4, indicating the unique features of this hydrofullerene in comparison to those of pristine C60. In addition, under specific orientations of the external field, certain π‐aromatic circuits are enabled, resulting in a more aromatic fullerene than that of C60, but lower than that of the spherical aromatic C606− fulleride. Notably, under a field aligned with the saturated carbon atoms, nonaromatic characteristics are exposed. This reveals that spherical‐like cages can involve a complex magnetic response that heavily depends on the orientation of the applied field.
Ruling pentagons: The 13C NMR spectrum and unique aromatic features of C2v C66H4, in which three π‐aromatic circuits are present at the bottom boat section of this fullerene derivative, are compared with those of pristine C60, employing DFT calculations.
Pelvic floor disorders (including urinary and anal incontinence and pelvic organ prolapse) are associated with childbirth. Injury to the pelvic floor muscles during vaginal childbirth, such as ...avulsion of the levator ani muscle, is associated with weaker pelvic floor muscle strength. As weak pelvic floor muscle strength may be a modifiable risk factor for the later development of pelvic floor disorders, it is important to understand how pelvic floor muscle strength affects the course of pelvic floor disorders over time.
To investigate the association between pelvic floor muscle strength and the incidence of pelvic floor disorders, and to identify maternal and obstetrical characteristics that modify the association.
This is a longitudinal study investigating pelvic floor disorders after childbirth. Participants were recruited 5–10 years after their first delivery and were assessed for pelvic floor disorders annually for up to 9 years. Stress incontinence, overactive bladder, and anal incontinence were assessed at each annual visit using the Epidemiology of Prolapse and Incontinence Questionnaire. Pelvic organ prolapse was assessed on physical examination, and was defined as descent of the vaginal walls or cervix beyond the hymen during forceful Valsalva. The primary exposure of interest was pelvic floor muscle strength, defined as the peak pressure during a voluntary pelvic muscle contraction (measured with a perineometer). The relationship between pelvic floor muscle strength and the cumulative incidence (time to event) of each pelvic floor disorder was evaluated using lognormal models, stratified by vaginal vs cesarean delivery. The relative hazard for each pelvic floor disorder (among those women free of the disorder at enrollment and thus more than 5–10 years from first delivery), was estimated using semiparametric proportional hazard models as a function of delivery mode, pelvic floor muscle strength, and other covariates.
Of 1143 participants, the median age was 40 (interquartile range, 36.6–43.7) years, and 73% were multiparous. On perineometry, women with at least 1 vaginal delivery were more likely to have a low peak pressure, defined as <20 cm H2O (243 of 588 women with at least 1 vaginal delivery vs 107 of 555 women who delivered all of their children by cesarean delivery, P < .001). Among women who had at least 1 vaginal delivery, a pelvic floor muscle strength of <20 cm H2O was associated with a shorter time to event for stress incontinence (time ratio, 0.67; 95% confidence interval, 0.50–0.90), overactive bladder (time ratio, 0.67; 95% confidence interval, 0.51–0.86), and pelvic organ prolapse (time ratio, 0.76; 95% confidence interval, 0.65–0.88). No such association was found among women who delivered all of their children by cesarean delivery. Among women with at least 1 vaginal delivery and considering only pelvic floor disorders that developed during study observation (5–10 years after the first delivery), and controlling for maternal characteristics (body mass index and genital hiatus), women who had a peak pressure of <20 cm H2O had hazard ratios (relative to ≥20 cm H2O) of 1.16 (95% confidence interval, 0.74–1.81) for stress incontinence, 1.27 (95% confidence interval, 0.78–2.05) for overactive bladder, and 1.43 (95% confidence interval, 0.99–2.07) for pelvic organ prolapse. Among women who delivered all of their children by cesarean delivery, there was no association between muscle strength and relative hazard of pelvic floor disorders when controlling for maternal characteristics.
After vaginal delivery, but not cesarean delivery, the cumulative incidence of pelvic organ prolapse, stress incontinence, and overactive bladder is associated with pelvic muscle strength, but the associations attenuate when adjusting for genital hiatus and body mass index.
During the past two decades, single‐atom‐centered medium‐sized germanium clusters M@Gen (M=transition metals, n>12) have been extensively explored, both from theoretical perspectives and experimental ...gas‐phase syntheses. However, the actual structural arrangements of the Ge13 and Ge14 endohedral cages are still ambiguous and have long remained an unresolved problem for experimental implementation. In this work, we successfully synthesize 13‐/14‐vertex Ge clusters Nb@Ge133− (1) and Nb@Ge143− (2), which are structurally characterized and exhibit unprecedented topologies, neither classical deltahedra nor 3‐connected polyhedral structures. Theoretical analysis indicates that the major stabilization of the Ge backbones arises due to the substantial interaction of Ge 4p‐AOs with the endohedral Nb 4d‐AOs through three/four‐center two‐electron bonds with an enhanced electron density accumulated over the shortest Nb−Ge13 contact in 1. Low occupancies of the direct two‐center two‐electron (2c–2e) Nb−Ge and Ge−Ge σ bonds point to a considerable degree of electron delocalization over the Ge cages revealing their electron deficiency.
Two new clusters Nb@Ge133− and Nb@Ge143− were successfully synthesized; they represent the first 13‐ and 14‐vertex endohedral Ge cages. HOMO‐2 orbital of Nb@Ge133− (left) shows a bonding character with respect to the shortest Nb−Ge contact, whereas the analogous HOMO‐2 orbital of Nb@Ge143− (right) shows anti‐bonding character over the related fragment.
Helicenes consist of several fused rings twisted around an axis, forming a cylindrical helix, with π‐delocalized electrons in the non‐planar rings. Induced magnetic fields dissecting the orbital ...contributions of 6‐, 7‐, and 14helicene are discussed. Computations show a deshielding cone produced by the π‐electrons along the helical axis. Unexpectedly, the response of the core electrons produces a shielding cone, which is cumulative and sensitive to the curvature of the systems owing to the overlap of the other ring responses. A warning is provided regarding the evaluation of the delocalization in curved systems in which the x‐ and y‐components of the induced magnetic field become relevant.
Induced magnetic fields dissecting the orbital contributions of 6‐, 7‐, and 14helicene are discussed. Computations show a deshielding cone produced by the π‐electrons along the helical axis. Unexpectedly, the response of the core electrons produces a shielding cone, which is cumulative and sensitive to the curvature of the systems owing to the overlap of the other ring responses.
Parametric and semiparametric competing risks methods were used to estimate proportions, timing, and predictors of acquired immune deficiency syndrome (AIDS)-related and non-AIDS-related mortality ...among individuals both positive and negative for the human immunodeficiency syndrome (HIV) in the Multicenter AIDS Cohort Study (MACS) and Women's Interagency HIV Study (WIHS) from 1984 to 2008 and 1996 to 2008, respectively. Among HIV-positive MACS participants, the proportion of deaths unrelated to AIDS increased from 6% before the introduction of highly active antiretroviral therapy (HAART) (before 1996) to 53% in the HAART era (P < 0.01); the median age of persons who died from non-AIDS-related causes after age 35 years increased from 49.0 to 66.0 years (P < 0.01). In both cohorts during the HAART era, median ages at time of non-AIDS-related death were younger for HIV-positive individuals than for comparable HIV-negative individuals (8.7 years younger in MACS (P < 0.01) and 7.6 years younger in WIHS (P < 0.01)). In a multivariate proportional cause-specific hazards model, unemployment (for non-AIDS death, hazard ratio (HR) = 1.8; for AIDS death, HR = 2.3), depression (for non-AIDS death, HR = 1.4; for AIDS death, HR = 1.4), and hepatitis B or C infection (for non-AIDS death, HR = 1.8, for AIDS death; HR = 1.4) were significantly (P < 0.05) associated with higher hazards of both non-AIDS and AIDS mortality among HIV-positive individuals in the HAART era, independent of study cohort. The results illuminate the changing face of mortality among the growing population infected with HIV.
The stabilization of gold nanoparticles by using thiolate-based ligands is a relevant issue in the design of functional nanostructures. Superatomic clusters, through the prominent Au25(SR)18 ...aggregate, offer a prototypical template to deepen the understanding of the different behaviors gained by the inclusion of different chalcogen atoms at the ligand layer. Through the study of Au25(XMe)18− (X = S, Se and Te), our results revealed that the bonding between the formally Au135+ core and the protecting layer (PL), further involves the unoccupied 1D-, 1F- and 2S-Au13 superatomic shells, acting as a charge acceptor in the PL → Au13 charge transfer upon formation of the cluster. In addition, the optical properties showed an increase in the Stokes shift between the S0 → S1 excitation, and S0 ← S1 emission, going from –SMe to –TeMe, owing to a more distorted core in the excited state for the heavier counterpart. The approach here employed expands the bonding picture between the Au135+ and the protecting layer between different anchor atoms, in addition to the formal ionic description of an isolated core. These findings seek to enhance our understanding of bonding, and the optical characteristic resulting from the use of heavier chalcogen atoms in the protecting layer, which can be employed as design guidelines to incorporate or modify the molecular properties towards the synthesis of ligand-protected gold clusters.
![[(Me3Si)Si]3EtGe9Pd(PPh3), ...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1433-7851/small "[(Me3Si)Si]3EtGe9Pd(PPh3), a Pentafunctionalized Deltahedral Zintl Cluster: Synthesis, Structure, and Solution Dynamics")
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