Cyclometallated Compounds of Palladium(ii), Rhodium(iii), and Iridium(iii).

A number of new complex compounds of palladium, gold, rhodium, iridium, and platinum have been synthesized and characterized. The organic ligands used in the preponderance of reactions involve some nitrogen heterocycle such as 2-arylpyridines, 2,6-diarylpyridines, benzo{h}quinoline, and caffeine. In most cases, the organic ligand underwent an intramolecular metallation (designated orthometallation or more generally cyclometallation ) with subsequent formation of a chelate ring containing a covalent metal to carbon bond. The effect of varying the substituents on the aryl moiety of the 2-arylpyridines supported the hypothesis that after initial N-complexation, the 2-position of the aryl nucleus experiences an electrophilic attack by the palladium atom. Several different palladium starting materials were used and it was found that: (a) Pd(acetylacetonate)(,2) did not react; (b) PdCl(,2)(C(,6)H(,5)CN)(,2) did not metallate, but did give a 2:1 (ligand-to-metal) adduct; and (c) both PdCl(,4)(\u272-) and Pd(CH(,3)COO)(,2) gave the desired cyclometallated products. Palladium(II) acetate has proven to be a more useful starting material than the tetrachloropalladata, since the resulting acetato-bridged dimers, unlike the chloro-bridged dimers, are soluble in polar organic solvents. Reactions of gold in such forms as AuCl(,4)(\u27-), (C(,6)H(,5))(,3)PAuCl, and dichloro-(mu)-1,2-bis(diphenylphosphino)ethanedigold(I) failed to produce any cyclometallated products under a broad assortment of conditions. Only compounds containing 1:1 (ligand to metal) adducts were formed. Occasionally, reduction to metallic gold occurred. Both rhodium and iridium formed biscyclometallated products containing two chelated rings per six-coordinated trivalent metal atom. In contrast to the four-coordinate palladium(II) chlorobridged dimers, the chloro-bridged dimers of rhodium and iridium were conveniently soluble in organic solvents. Platinum formed a compound which was analogous to those of the palladium chloro-bridged dimers. Detailed high resolution (\u271)H NMR studies (200 MHz) showed that cyclometallation did occur on the aryl nucleus of the 2-arylpyridines. The 6-heteroaryl protons and those \u27ortho\u27 to the metal-carbon bond are both shifted from the free ligand position. Depending on the metal, the shifts are either up- or downfield. These shifts can be explained by either through-space interactions of overlying aromatic rings and/or through-bond (metal-to-ligand) effects. The (\u271)H NMR spectra of these biscyclometallated rhodium and iridium complexes have established a trans-nitrogen octahedral structure for all of these d(\u276) compounds. Both acetato- and chloro-bridged dimers react with certain ligands to give mononuclear complexes containing the intact cyclometallated ligand. (\u271)H NMR studies of palladium and rhodium complexes containing diethyldithiocarbamate and 2-arylpyridines as chelating ligands strongly suggest that in the d(\u278) palladium compound there is metal-to-ligand back bonding whereas in the d(\u276) rhodium compound no such bonding occurs. Furthermore, in the former complex the methyl groups are found to be in non-equivalent sites while the methylene protons are in equivalent sites. The reverse is true for the latter (Rh) complex. These observations are explained by the different structures of the Pd and Rh complexes, but more importantly by different metal-ligand bonding to both the arylpyridine and the dtc ligands. The nitrogen of the dtc ligand appears to be sp(\u273) in the Rh complex and closer to sp(\u272) in the Pd complex. Single crystal X-ray determinations have confirmed that metallation of an aryl ring of both 2-arylpyridines and 2,6-diarylpyridines has occurred

Characterising and Verifying the Core in Concurrent Multi-Player Mean-Payoff Games (Full Version)

Concurrent multi-player mean-payoff games are important models for systems of agents with individual, non-dichotomous preferences. Whilst these games have been extensively studied in terms of their equilibria in non-cooperative settings, this paper explores an alternative solution concept: the core from cooperative game theory. This concept is particularly relevant for cooperative AI systems, as it enables the modelling of cooperation among agents, even when their goals are not fully aligned. Our contribution is twofold. First, we provide a characterisation of the core using discrete geometry techniques and establish a necessary and sufficient condition for its non-emptiness. We then use the characterisation to prove the existence of polynomial witnesses in the core. Second, we use the existence of such witnesses to solve key decision problems in rational verification and provide tight complexity bounds for the problem of checking whether some/every equilibrium in a game satisfies a given LTL or GR(1) specification. Our approach is general and can be adapted to handle other specifications expressed in various fragments of LTL without incurring additional computational costs.Comment: This is the full version of the paper with the same title that appears in the CSL'24 proceeding

MMP13 and TIMP1 are functional markers for two different potential modes of action by mesenchymal stem/stromal cells when treating osteoarthritis

Mesenchymal stem cells (MSCs) have been investigated as a potential injectable therapy for the treatment of knee osteoarthritis, with some evidence of success in preliminary human trials. However, optimization and scale‐up of this therapeutic approach depends on the identification of functional markers that are linked to their mechanism of action. One possible mechanism is through their chondrogenic differentiation and direct role in neo‐cartilage synthesis. Alternatively, they could remain undifferentiated and act through the release of trophic factors that stimulate endogenous repair processes within the joint. Here, we show that extensive in vitro aging of bone marrow‐derived human MSCs leads to loss of chondrogenesis but no reduction in trophic repair, thereby separating out the two modes of action. By integrating transcriptomic and proteomic data using Ingenuity Pathway Analysis, we found that reduced chondrogenesis with passage is linked to downregulation of the FOXM1 signaling pathway while maintenance of trophic repair is linked to CXCL12. In an attempt at developing functional markers of MSC potency, we identified loss of mRNA expression for MMP13 as correlating with loss of chondrogenic potential of MSCs and continued secretion of high levels of TIMP1 protein as correlating with the maintenance of trophic repair capacity. Since an allogeneic injectable osteoar therapy would require extensive cell expansion in vitro, we conclude that early passage MMP13+, TIMP1‐secretinghigh MSCs should be used for autologous OA therapies designed to act through engraftment and chondrogenesis, while later passage MMP13−, TIMP1‐secretinghigh MSCs could be exploited for allogeneic OA therapies designed to act through trophic repair

First results from the Very Small Array -- I. Observational methods

The Very Small Array (VSA) is a synthesis telescope designed to image faint structures in the cosmic microwave background on degree and sub-degree angular scales. The VSA has key differences from other CMB interferometers with the result that different systematic errors are expected. We have tested the operation of the VSA with a variety of blank-field and calibrator observations and cross-checked its calibration scale against independent measurements. We find that systematic effects can be suppressed below the thermal noise level in long observations; the overall calibration accuracy of the flux density scale is 3.5 percent and is limited by the external absolute calibration scale.Comment: 9 pages, 10 figures, MNRAS in press (Minor revisions

Essential Role for the C5a Receptor in Regulating the Effector Phase of Synovial Infiltration and Joint Destruction in Experimental Arthritis

A characteristic feature of rheumatoid arthritis is the abundance of inflammatory cells in the diseased joint. Two major components of this infiltrate are neutrophils in the synovial fluid and macrophages in the synovial tissue. These cells produce cytokines including tumor necrosis factor α and other proinflammatory mediators that likely drive the disease through its effector phases. To investigate what mechanisms underlie the recruitment of these cells into the synovial fluid and tissue, we performed expression analyses of chemoattractant receptors in a related family that includes the anaphylatoxin receptors and the formyl-MetLeuPhe receptor. We then examined the effect of targeted disruption of two abundantly expressed chemoattractant receptors, the receptors for C3a and C5a, on arthritogenesis in a mouse model of disease. We report that genetic ablation of C5a receptor expression completely protects mice from arthritis

Are Physical Activity and Sedentary Screen Time Levels Associated With Food Consumption in European Adolescents? The HELENA Study

Objective: One of the current main public health problems is the prevalence of obesity in children. Unhealthy lifestyle behaviors such as poor dietary habits, high sedentary screen time (SST), and low levels of physical activity (PA) have a strong tendency to track from childhood into adulthood. The aim of this manuscript is to assess the association between meeting or not meeting the PA and SST recommendations and the consumption of different food groups. Method: Data were obtained from a sample of European adolescents from the multicenter cross-sectional HELENA study. In all, 1448 adolescents from 8 cities were included. PA was objectively measured by accelerometry and dietary intake by 24-hour dietary records. Adolescents were grouped according to PA and SST recommendations. Results: In both sexes, intake of savory snacks was higher in those groups who did not meet any of the recommendations (p < 0.05). For males, those who met both recommendations were more likely to drink/eat milk, yogurt, and water (p < 0.05). Those not meeting recommendations were more likely to drink sugar-sweetened beverages (p < 0.05). For females, those not meeting recommendations were less likely to eat fruits and vegetables and more likely to have a higher intake of fats and oils (p < 0.05). Conclusions: Those adolescents meeting PA and SST recommendations had a higher intake of healthy foods, like fruit and vegetables and dairy products. However, the negative relationship unhealthier food and SST is stronger in males independently of PA. More studies assessing the combined effect of both PA and SST regarding dietary habits in children and adolescents are needed

Bayesian analysis of weak gravitational lensing and Sunyaev-Zel'dovich data for six galaxy clusters

We present an analysis of observations made with the Arcminute Microkelvin Imager (AMI) and the Canada-France-Hawaii Telescope (CFHT) of six galaxy clusters in a redshift range of 0.16--0.41. The cluster gas is modelled using the Sunyaev--Zel'dovich (SZ) data provided by AMI, while the total mass is modelled using the lensing data from the CFHT. In this paper, we: i) find very good agreement between SZ measurements (assuming large-scale virialisation and a gas-fraction prior) and lensing measurements of the total cluster masses out to r_200; ii) perform the first multiple-component weak-lensing analysis of A115; iii) confirm the unusual separation between the gas and mass components in A1914; iv) jointly analyse the SZ and lensing data for the relaxed cluster A611, confirming our use of a simulation-derived mass-temperature relation for parameterizing measurements of the SZ effect.Comment: 22 pages, 12 figures, 12 tables, published by MNRA

First results from the Very Small Array -- III. The CMB power spectrum

We present the power spectrum of the fluctuations in the cosmic microwave background detected by the Very Small Array (VSA) in its first season of observations in its compact configuration. We find clear detections of first and second acoustic peaks at l~200 and l~550, plus detection of power on scales up to l=800. The VSA power spectrum is in very good agreement with the results of the Boomerang, Dasi and Maxima telescopes despite the differing potential systematic errors.Comment: 10 pages, 6 figure, MNRAS in press. (Minor revisions - accepted 17 December 2002

First results from the Very Small Array -- II. Observations of the CMB

We have observed the cosmic microwave background temperature fluctuations in eight fields covering three separated areas of sky with the Very Small Array at 34 GHz. A total area of 101 square degrees has been imaged, with sensitivity on angular scales 3.6 - 0.4 degrees (equivalent to angular multipoles l=150-900). We describe the field selection and observing strategy for these observations. In the full-resolution images (with synthesised beam of FWHM ~ 17 arcmin) the thermal noise is typically 45 microK and the CMB signal typically 55 microK. The noise levels in each field agree well with the expected thermal noise level of the telescope, and there is no evidence of any residual systematic features. The same CMB features are detected in separate, overlapping observations. Discrete radio sources have been detected using a separate 15 GHz survey and their effects removed using pointed follow-up observations at 34 GHz. We estimate that the residual confusion noise due to unsubtracted radio sources is less than 14 mJy/beam (15 microK in the full-resolution images), which added in quadrature to the thermal noise increases the noise level by 6 %. We estimate that the rms contribution to the images from diffuse Galactic emission is less than 6 microK. We also present images which are convolved to maximise the signal-to-noise of the CMB features and are co-added in overlapping areas, in which the signal-to-noise of some individual CMB features exceeds 8.Comment: 11 pages, 5 figures, accepted for publication in MNRAS. Replaces original version - more detailed abstract, corrected typo