Synthesis and structural studies of a lanthanide complex of a calix[4]arene tris-amide

The coordination chemistry of amide-substituted calixarenes is reviewed. The synthesis of a gadolinium complex of a trisamide calix[4]arene is described, involving the reaction of 5,11,17,23-tetra-tert-butyl-24-hydroxy-26,27,28-tris(diethylcarbamoylmethoxy) calix[4]arene (L) with gadolinium picrate dodecahydrate. Structural studies demonstrated that the complex can be formulated as [(pic-O)Gd{(L H)(EtOH)}](pic)2 EtOH

Alfred Werner revisited: Some subtleties of complex ion synthesis and isomerism

The synthesis of perhaps the best-known Wernerian complex, [Co(en)3]3+, is very efficient, but nonetheless results in the formation of various side-products. Today, the use of X-ray crystallography to characterise such materials provides new insights into the reaction pathways of the synthesis and the exact forms possible for the products. The structures of cis-[Co(en)2(H2NCH2CH2NH3)Cl]Cl[ZnCl4], cis-[Co(en)2(NH3)Cl]S2O6, [Co(en)(NH2CH2CH2N=CHCH2NH2))Cl][ZnCl4], [Co(en)2(N-CH3en)][Co(CN)6]?2 H2O and [Co(en)2(N-CH3en)][Co(CN)6], are presently discussed in this regard

Performance of formulae based estimates of glomerular filtration rate for carboplatin dosing in stage 1 seminoma

<b>Background:</b> Single cycle carboplatin, dosed by glomerular filtration rate (GFR), is standard adjuvant therapy for stage 1 seminoma. Accurate measurement of GFR is essential for correct dosing. Isotopic methods remain the gold standard for the determination of GFR. Formulae to estimate GFR have improved the assessment of renal function in non-oncological settings. We assessed the utility of these formulae for carboplatin dosing.<p></p> <b>Methods:</b> We studied consecutive subjects receiving adjuvant carboplatin for stage 1 seminoma at our institution between 2007 and 2012. Subjects underwent 51Cr-ethylene diamine tetra-acetic acid (EDTA) measurement of GFR with carboplatin dose calculated using the Calvert formula. Theoretical carboplatin doses were calculated from estimated GFR using Chronic Kidney Disease-Epidemiology (CKD-EPI), Management of Diet in Renal Disease (MDRD) and Cockcroft–Gault (CG) formulae with additional correction for actual body surface area (BSA). Carboplatin doses calculated by formulae were compared with dose calculated by isotopic GFR; a difference <10% was considered acceptable.<p></p> <b>Results:</b> 115 patients were identified. Mean isotopic GFR was 96.9 ml/min/1.73 m2. CG and CKD-EPI tended to overestimate GFR whereas MDRD tended to underestimate GFR. The CKD-EPI formula had greatest accuracy. The CKD-EPI formula, corrected for actual BSA, performed best; 45.9% of patients received within 10% of correct carboplatin dose. Patients predicted as underdosed (13.5%) by CKD-EPI were more likely to be obese (p = 0.013); there were no predictors of the 40.5% receiving an excess dose.<p></p> <b>Conclusions:</b> Our data support further evaluation of the CKD-EPI formula in this patient population but clinically significant variances in carboplatin dosing occur using non-isotopic methods of GFR estimation. Isotopic determination of GFR should remain the recommended standard for carboplatin dosing when accuracy is essential.<p></p&gt

Multiepoch Radial Velocity Observations of L Dwarfs

We report on the development of a technique for precise radial-velocity measurements of cool stars and brown dwarfs in the near infrared. Our technique is analogous to the Iodine (I2) absorption cell method that has proven so successful in the optical regime. We rely on telluric CH4 absorption features to serve as a wavelength reference, relative to which we measure Doppler shifts of the CO and H2O features in the spectra of our targets. We apply this technique to high-resolution (R~50,000) spectra near 2.3 micron of nine L dwarfs taken with the Phoenix instrument on Gemini-South and demonstrate a typical precision of 300 m/s. We conduct simulations to estimate our expected precision and show our performance is currently limited by the signal-to-noise of our data. We present estimates of the rotational velocities and systemic velocities of our targets. With our current data, we are sensitive to companions with M sin i > 2MJ in orbits with periods less than three days. We identify no companions in our current data set. Future observations with improved signal-to-noise should result in radial-velocity precision of 100 m/s for L dwarfs.Comment: Accepted for publication in ApJ, 24 pages, 7 figure

C4 Dissymmetric resorcinarene derivatives: synthesis, crystal structure and micelle formation

The synthesis of a C4 dissymmetric resorcinarene tetracarboxylic acid derivative and determination of its critical micelle concentration is reported. The tetrahydroxy derivative was prepared by reduction of the tetra-acid. The low-temperature single crystal X-ray structure of the methyl ester derivative of the tetra-acid is also reported. This crystallised with two independent molecules of similar boat (flattened cone) conformation within the asymmetric unit

Heavy Quark Fragmentation to Baryons Containing Two Heavy Quarks

We discuss the fragmentation of a heavy quark to a baryon containing two heavy quarks of mass $m_Q\gg\Lambda_{\rm QCD}$. In this limit the heavy quarks first combine perturbatively into a compact diquark with a radius small compared to $1/\Lambda_{\rm QCD}$, which interacts with the light hadronic degrees of freedom exactly as does a heavy antiquark. The subsequent evolution of this $QQ$ diquark to a $QQq$ baryon is identical to the fragmentation of a heavy antiquark to a meson. We apply this analysis to the production of baryons of the form $ccq$, $bbq$, and $bcq$.Comment: 9 pages, 1 figure included, uses harvmac.tex and epsf.tex, UCSD/PTH 93-11, CALT-68-1868, SLAC-PUB-622

Methods of Higher Alcohol Synthesis

Systems, catalysts, and methods are provided for transforming carbon based material into synthetic mixed alcohol fuel

Comparison of Sports Medicine Questions on the Orthopaedic In-Training Examination Between 2009 and 2012 and 2017 and 2020 Reveals an Increasing Number of References

Purpose To provide an updated analysis of the sports medicine section of the Orthopedic In-Training Examination (OITE). Methods A cross-sectional review of OITE sports medicine questions from 2009 to 2012 and 2017-2020 was performed. Subtopics, taxonomy, references, and use of imaging modalities were recorded and changes between the time periods were analyzed. Results The most tested sports medicine subtopics included ACL (12.6%), rotator cuff (10.5%), and throwing injuries to the shoulder (7.4%) in the early subset, while ACL (10%), rotator cuff (6.25%), shoulder instability (6.25%), and throwing injuries to the elbow (6.25%) were the most common in the later subset. The American Journal of Sports Medicine (28.3%) was the most cited journal referenced from 2009 to 2012, while The Journal of the American Academy of Orthopaedic Surgeons (17.5%) was most referenced in questions from 2017 to 2020. The number of references per question increased from the early to the late subset (P \u3c .001). There was a trend toward an increased taxonomy type one questions (P = .114), while type 2 questions had a decreased trend (P = .263) when comparing the new subset to the early group. Conclusion When comparing sports medicine OITE questions from 2009 to 2012 and 2017 to 2020, there was an increase in the number of references per question. Subtopics, taxonomy, lag time, and use of imaging modalities did not show statistically significant changes. Clinical Relevance This study provides a detailed analysis of the sports medicine section of the OITE, which can be used by residents and program directors to direct their preparation for the annual examination. The results of this study may help examining boards align their examinations and provide a benchmark for future studies

Exploring Fully Offloaded GPU Stream-Aware Message Passing

Modern heterogeneous supercomputing systems are comprised of CPUs, GPUs, and high-speed network interconnects. Communication libraries supporting efficient data transfers involving memory buffers from the GPU memory typically require the CPU to orchestrate the data transfer operations. A new offload-friendly communication strategy, stream-triggered (ST) communication, was explored to allow offloading the synchronization and data movement operations from the CPU to the GPU. A Message Passing Interface (MPI) one-sided active target synchronization based implementation was used as an exemplar to illustrate the proposed strategy. A latency-sensitive nearest neighbor microbenchmark was used to explore the various performance aspects of the implementation. The offloaded implementation shows significant on-node performance advantages over standard MPI active RMA (36%) and point-to-point (61%) communication. The current multi-node improvement is less (23% faster than standard active RMA but 11% slower than point-to-point), but plans are in progress to purse further improvements.Comment: 12 pages, 17 figure

Discovery of a Classic FR-II Broad Absorption Line Quasar from the FIRST Survey

We have discovered a remarkable quasar, FIRST J101614.3+520916, whose optical spectrum shows unambiguous broad absorption features while its double-lobed radio morphology and luminosity clearly indicate a classic Fanaroff-Riley Type II radio source. Its radio luminosity places it at the extreme of the recently established class of radio-loud broad absorption line quasars (Becker et al. 1997, 2000; Brotherton et al. 1998). Because of its hybrid nature, we speculate that FIRST J101614.3+520916 is a typical FR-II quasar which has been rejuvenated as a broad absorption line (BAL) quasar with a Compact Steep Spectrum core. The direction of the jet axis of FIRST J101614.3+520916 can be estimated from its radio structure and optical brightness, indicating that we are viewing the system at a viewing angle of > 40 degrees. The position angles of the radio jet and optical polarization are not well-aligned, differing by 20 to 30 degrees. When combined with the evidence presented by Becker et al. (2000) for a sample of 29 BAL quasars showing that at least some BAL quasars are viewed along the jet axis, the implication is that no preferred viewing orientation is necessary to observe BAL systems in a quasar's spectrum. This, and the probable young nature of compact steep spectrum sources, leads naturally to the alternate hypothesis that BALs are an early stage in the lives of quasars.Comment: 14 pages, 6 postscript figures; accepted for publication in the Astrophysical Journa