Platinum(II) phosphonate complexes derived from endo-8-camphanylphosphonic acid

The reactions of cis-[PtCl₂L₂] [L = PPh₃, PMe₂Ph or L₂ = Ph₂P(CH₂)₂PPh₂ (dppe)] with endo-8-camphanylphosphonic acid (CamPO₃H₂) and Ag₂O in refluxing dichloromethane gave platinum(II) phosphonate complexes [Pt(O₃PCam)L₂]. The X-ray crystal structure of [Pt(O₃PCam)(PPh₃)₂]•₂CHCl₃ shows that the bulky camphanyl group, rather than being directed away from the platinum, is instead directed into a pocket formed by the Pt and the two PPh₃ ligands. This allows the O₃P–CH₂ group to have a preferred staggered conformation. The complexes were studied in detail by NMR spectroscopy, which demonstrates non-fluxional behaviour for the sterically bulky PPh₃ and dppe derivatives, which contain inequivalent phosphine ligands in their ³¹P NMR spectra. These findings are backed up by theoretical calculations on the PPh₃ and PPhMe₂ derivatives, which show, respectively, high and low energy barriers to rotation of the camphanyl group in the PPh₃ and PPhMe₂ complexes. The X-ray crystal structure of CamPO₃H₂ is also reported, and consists of hydrogen-bonded hexameric aggregates, which assemble to form a columnar structure containing hydrophilic phosphonic acid channels surrounded by a sheath of bulky, hydrophobic camphanyl groups

Di- and Trinuclear Mixed-Valence Copper Amidinate Complexes from Reduction of Iodine

Molecular examples of mixed-valence copper complexes through chemical oxidation are rare but invoked in the mechanism of substrate activation, especially oxygen, in copper-containing enzymes. To examine the cooperative chemistry between two metals in close proximity to each other we began studying the reactivity of a dinuclear Cu(I) amidinate complex. The reaction of [(2,6-Me2C6H3N)2C(H)]2Cu2, 1, with I2 in tetrahydrofuran (THF), CH3CN, and toluene affords three new mixed-valence copper complexes [(2,6-Me2C6H3N)2C(H)]2Cu2(μ2-I3)(THF)2, 2, [(2,6-Me2C6H3N)2C(H)]2Cu2(μ2-I) (NCMe)2, 3, and [(2,6-Me2C6H3N)2C(H)]3Cu3(μ3-I)2, 4, respectively. The first two compounds were characterized by UV-vis and electron paramagnetic resonance spectroscopies, and their molecular structure was determined by X-ray crystallography. Both di- and trinuclear mixed-valence intermediates were characterized for the reaction of compound 1 to compound 4, and the molecular structure of 4 was determined by X-ray crystallography. The electronic structure of each of these complexes was also investigated using density functional theory

A COST-EFFECTIVE MODEL FOR TEACHING ELEMENTARY STATISTICS WITH IMPROVED STUDENT PERFORMANCE

Dissatisfaction with teaching a high enrollment introductory statistics course led to efforts to restructure the course to remedy the perceived problems, including lack of student participation, an excessive drain on departmental resources, failure to take into account wide differences in student learning styles, an inability of students to apply statistics after the course, and negative attitudes of students. A cost-effective redesign of the course was implemented that incorporates a learning environment that is student-oriented, involves active student participation and hands-on experience with data analysis, uses technology to reduce costs through labor-saving techniques including low-stakes computerized testing, and sharing of resources enabled by a web site for course management and delivery of course materials. Responsibility for learning basic concepts was transferred to students and motivated by readiness assessment quizzes. The redesign led to about $125,000 in cost savings to the department

Abstract

AimsPatients with spinal cord injury (SCI) are at risk of developing renal calculi. This study describes the management of renal calculi among patients with SCI with attention to factors influencing surgical management vs observation.MethodsThis retrospective, cohort study identified patients with SCI and renal calculi between 2009 to 2016 from an institutional neurogenic bladder database and detailed the management of their stones. A stone episode was defined as radiographic evidence of new calculi.ResultsOf 205 patients with SCI, 34 had renal stones, for a prevalence of 17%. The mean age was 50 years (range 22,77) and most had cervical SCI (n = 22, 65%). There were 41 stone episodes with 98 individual stones identified with a mean stone size of 4.9 mm (range 1‐19).Of the 41 episodes, 10 (24%) underwent surgery after initial diagnosis. Pain was the most common primary indication for surgery (n = 9, 60%). The median time from diagnosis to intervention for all patients was 4 months (interquartile range 1,23). Of the 41 episodes, 31 (76%) were initially observed and among these, 5 ultimately required surgery (16%) while 26 (84%) did not. Of these 26, 12 (46%) stones passed spontaneously and 14 (53%) remained unchanged. The need for surgery correlated with more stone episodes (P = .049).ConclusionIn this cohort of patients with SCI and small, nonobstructing renal stones, 76% (n = 31) were offered observation. Of these observed patients, 84% (n = 26) did not require further intervention at a median of 4 years of follow‐up.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151315/1/nau24091.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151315/2/nau24091_am.pd

The fundamental pro-groupoid of an affine 2-scheme

A natural question in the theory of Tannakian categories is: What if you don't remember \Forget? Working over an arbitrary commutative ring $R$, we prove that an answer to this question is given by the functor represented by the \'etale fundamental groupoid \pi_1(\spec(R)), i.e.\ the separable absolute Galois group of $R$ when it is a field. This gives a new definition for \'etale \pi_1(\spec(R)) in terms of the category of $R$-modules rather than the category of \'etale covers. More generally, we introduce a new notion of "commutative 2-ring" that includes both Grothendieck topoi and symmetric monoidal categories of modules, and define a notion of $\pi_1$ for the corresponding "affine 2-schemes." These results help to simplify and clarify some of the peculiarities of the \'etale fundamental group. For example, \'etale fundamental groups are not "true" groups but only profinite groups, and one cannot hope to recover more: the "Tannakian" functor represented by the \'etale fundamental group of a scheme preserves finite products but not all products.Comment: 46 pages + bibliography. Diagrams drawn in Tik

Reactivity of the metalloligand [Pt2(µ-S)2(PPh3)4] toward tellurium(II) thiourea complexes: synthesis and structural characterization of the ditellurium(I) derivative [{Pt2(µ-S)2(PPh3)4}2Te2]2+

Reaction of the platinum(II) sulfide metalloligand [Pt2(µ-S)2(PPh3)4] with the tellurium(II) source TeCl2(tu)2 (tu = thiourea) is dependent on reaction conditions employed. In the presence of added acid, the dominant species observed in the electrospray ionization (ESI) mass spectrum is the tetraplatinum species [{Pt2(µ-S)2(PPh3)4}2Te2]2+. This contains the Te22+ moiety and is related to the previously reported tellurium(I) dithiophosphinate analog [(Ph2PS2)2Te2]. However, in the absence of acid, considerable degradation of the {Pt2S2} metalloligand occurs as evidenced by the formation of the mononuclear complex [Pt{SC(NH2)NH}(PPh3)2]+ containing a deprotonated thiourea ligand, together with other thiourea-containing ions, identified by ESI MS. Likewise, attempted use of a fully substituted thiourea, viz. Me2NC(S)NMe2 (tmtu) in TeCl2(tmtu)2, also resulted in degradation of the {Pt2S2} core and detection of the known complex [(Ph3P)2PtCl{SC(NMe2)2}]+. The [{Pt2(µ-S)2(PPh3)4}2Te2]2+ cation was isolated with several anions, and unequivocal confirmation of the structure of the complex was obtained by an X-ray structure determination on the BF4- salt, which shows the presence of the Te22+ unit, with the Te–Te bond bridged by two {Pt2S2} metalloligands. Density functional theory was used to further probe the Te22+ bonding interactions in [{Pt2(μ-S)2(PPh3)4}2Te2]2+ and the previously reported [(Ph2PS2)2Te2

Phosphorylation regulates targeting of cytoplasmic dynein to kinetochores during mitosis

Cytoplasmic dynein functions at several sites during mitosis; however, the basis of targeting to each site remains unclear. Tandem mass spectrometry analysis of mitotic dynein revealed a phosphorylation site in the dynein intermediate chains (ICs) that mediates binding to kinetochores. IC phosphorylation directs binding to zw10 rather than dynactin, and this interaction is needed for kinetochore dynein localization. Phosphodynein associates with kinetochores from nuclear envelope breakdown to metaphase, but bioriented microtubule (MT) attachment and chromosome alignment induce IC dephosphorylation. IC dephosphorylation stimulates binding to dynactin and poleward streaming. MT depolymerization, release of kinetochore tension, and a PP1-γ mutant each inhibited IC dephosphorylation, leading to the retention of phosphodynein at kinetochores and reduced poleward streaming. The depletion of kinetochore dynactin by moderate levels of p50(dynamitin) expression disrupted the ability of dynein to remove checkpoint proteins by streaming at metaphase but not other aspects of kinetochore dynein activity. Together, these results suggest a new model for localization of kinetochore dynein and the contribution of kinetochore dynactin

The Muon Anomalous Magnetic Moment: A Harbinger For "New Physics"

QED, Hadronic, and Electroweak Standard Model contributions to the muon anomalous magnetic moment, a_mu = (g_mu-2)/2, and their theoretical uncertainties are scrutinized. The status and implications of the recently reported 2.6 sigma experiment vs.theory deviation a_mu^{exp}-a_mu^{SM} = 426(165) times 10^{-11} are discussed. Possible explanations due to supersymmetric loop effects with m_{SUSY} \simeq 55 sqrt{tan beta} GeV, radiative mass mechanisms at the 1--2 TeV scale and other ``New Physics'' scenarios are examined.Comment: 24 page

Associations of vitamin D pathway genes with circulating 25-hydroxyvitamin-D, 1,25-dihydroxyvitamin-D, and prostate cancer:a nested case-control study

Vitamin D pathway single nucleotide polymorphisms (SNPs) are potentially useful proxies for investigating whether circulating vitamin D metabolites [total 25-hydroxyvitamin-D, 25(OH)D; 1,25-dihydroxyvitamin, 1,25(OH)2D] are causally related to prostate cancer. We investigated associations of sixteen SNPs across seven genes with prostate-specific antigen-detected prostate cancer