Synthesis, structural characterization, and ligand replacement reactions of gem-dithiolato-bridged rhodium and iridium complexes

The reaction of gem-dithiol compounds R2C(SH)2 (R = Bn (benzyl), iPr; R2 = −(CH2)4−) with dinuclear rhodium or iridium complexes containing basic ligands such as [M(μ-OH)(cod)]2 and [M(μ-OMe)(cod)]2, or the mononuclear [M(acac)(cod)] (M = Rh, Ir, cod = 1,5-cyclooctadiene) in the presence of a external base, afforded the dinuclear complexes [M2(μ-S2CR2)(cod)2] (1−4). The monodeprotonation of 1,1-dimercaptocyclopentane gave the mononuclear complex [Rh(HS2Cptn)(cod)] (5) that is a precursor for the dinuclear compound [Rh2(μ-S2Cptn)(cod)2] (6). Carbonylation of the diolefin compounds gave the complexes [Rh2(μ-S2CR2)(CO)4] (7−9), which reacted with P-donor ligands to stereoselectively produce the trans isomer of the disubstituted complexes [Rh2(μ-S2CR2)(CO)2(PR′3)2] (R′ = Ph, Cy (cyclohexyl)) (10−13) and [Rh2(μ-S2CBn2)(CO)2{P(OR′)3}2] (R′ = Me, Ph) (14−15). The substitution process in [Rh2(μ-S2CBn2)(CO)4] (7) by P(OMe)3 has been studied by spectroscopic means and the full series of substituted complexes [Rh2(μ-S2CBn2)(CO)4−n{P(OR)3}n] (n = 1, 4) has been identified in solution. The cis complex [Rh2(μ-S2CBn2)(CO)2(μ-dppb)] (16) was obtained by reaction of 7 with the diphosphine dppb (1,4-bis(diphenylphosphino)butane). The molecular structures of the diolefinic dinuclear complexes [Rh2(μ-S2CR2)(cod)2] (R = Bn (1), iPr (2); R2 = −(CH2)4− (6)) and that of the cis complex 16 have been studied by X-ray diffraction.The financial support from Ministerio de Educación y Ciencia (MEC/FEDER) Project CTQ2006-03973/BQU is gratefully acknowledged. A. B. R. thanks the Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo (CYTED) for a fellowship. Also, A.B. R. and A.J. P. thank to Fonacit-Venezuela (S1-2002000260) for financial support.Peer Reviewe

A Map-Reduce Parallel Approach to Automatic Synthesis of Control Software

Many Control Systems are indeed Software Based Control Systems, i.e. control systems whose controller consists of control software running on a microcontroller device. This motivates investigation on Formal Model Based Design approaches for automatic synthesis of control software. Available algorithms and tools (e.g., QKS) may require weeks or even months of computation to synthesize control software for large-size systems. This motivates search for parallel algorithms for control software synthesis. In this paper, we present a Map-Reduce style parallel algorithm for control software synthesis when the controlled system (plant) is modeled as discrete time linear hybrid system. Furthermore we present an MPI-based implementation PQKS of our algorithm. To the best of our knowledge, this is the first parallel approach for control software synthesis. We experimentally show effectiveness of PQKS on two classical control synthesis problems: the inverted pendulum and the multi-input buck DC/DC converter. Experiments show that PQKS efficiency is above 65%. As an example, PQKS requires about 16 hours to complete the synthesis of control software for the pendulum on a cluster with 60 processors, instead of the 25 days needed by the sequential algorithm in QKS.Comment: To be submitted to TACAS 2013. arXiv admin note: substantial text overlap with arXiv:1207.4474, arXiv:1207.409

Novel gem-dithiolato-bridged rhodium hydroformylation catalysts: Bridging the gap in dinuclear rhodium thiolate chemistry

The direct protonation of the bridging hydroxo ligands in [Rh(μ-OH)(cod)]2 by 1,1-dimercaptocyclohexane [Chxn(SH) 2] yields the gem-dithiolato-bridged compound [Rh2(μ- S2Chxn)-(cod)2] (1). The dinuclear framework in 1 is supported by a 1,1-cyclohexanedithiolato ligand exhibiting a 1:2κ2S,1:2κ2S′ coordination mode. Compound 1 is an active catalyst precursor in the presence of P-donor ligands for the hydroformylation of oct-1-ene under mild conditions of pressure and temperature (100 PSI, 353 K). The best results were obtained with phosphite ligands as modifying ligands. An aldehyde selectivity of 97 %, a regioselectivity towards the linear aldehyde of 81 %, and turnover frequencies of up to 198 h-1 were obtained with the catalytic system 1/P(OMe)3. The dinuclear compound [Rh2(μ-S 2Chxn)(CO)2(PPh3)2] (2) was isolated from the catalytic solutions resulting from the system 1/PPh3 and was characterized by spectroscopic means and by X-ray diffraction to be the frans isomer. The mixed-ligand dinuclear complexes 2 and [Rh2(μ- S2Chxn)(CO)2(PCy3)2] (3) (Cy = cyclohexyl) were independently prepared by reaction of Chxn(SH)2 with the mononuclear complexes [Rh(acac)(CO)-(PR3)] in the appropriate molar ratio.The financial support from Ministerio de Educación y Ciencia (MEC/FEDER) is gratefully acknowledged (Project CTQ2006-03973/BQU and Factoría de Cristalización, CONSOLIDER INGENIO-2010). A. B. R. thanks the Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo (CYTED, Project V.9) for a fellowship. A. J. P. thanks to Fonacit-Venezuela (S1-2002000260) for financial support.Peer Reviewe

Caracteristicas anatómicas de una nueva especie de Compsus (Coleoptera : Curculionidae) plaga de cítricos en Colombia.

Sociedad Colombiana de Entomología - SOCOLE

Impact of R&D expenditures, rainfall and temperature variations in agricultural productivity: empirical evidence from Bangladesh

No embargo required

A global surveillance system for crop diseases

To satisfy a growing demand for food, global agricultural production must increase by 70% by 2050. However, pests and crop diseases put global food supplies at risk. Worldwide, yield losses caused by pests and diseases are estimated to average 21.5% in wheat, 30.0% in rice, 22.6% in maize, 17.2% in potato, and 21.4% in soybean (1); these crops account for half of the global human calorie intake (2). Climate change and global trade drive the distribution, host range, and impact of plant diseases (3), many of which can spread or reemerge after having been under control (4). Though many national and regional plant protection organizations (NPPOs and RPPOs) work to monitor and contain crop disease outbreaks, many countries, particularly low-income countries (LICs), do not efficiently exchange information, delaying coordinated responses to prevent disease establishment and spread. To improve responses to unexpected crop disease spread, we propose a Global Surveillance System (GSS) that will extend and adapt established biosecurity practices and networking facilities into LICs, enabling countries and regions to quickly respond to emerging disease outbreaks to stabilize food supplies, enhancing global food protection

Agricultural R&D, technology and productivity.

Published versio

Prima facie reasons to question enclosed intellectual property regimes and favor open-source regimes for germplasm

In principle, intellectual property protections (IPPs) promote and protect important but costly investment in research and development. However, the empirical reality of IPPs has often gone without critical evaluation, and the potential of alternative approaches to lend equal or greater support for useful innovation is rarely considered. In this paper, we review the mounting evidence that the global intellectual property regime (IPR) for germplasm has been neither necessary nor sufficient to generate socially beneficial improvements in crop plants and maintain agrobiodiversity. Instead, based on our analysis, the dominant global IPR appears to have contributed to consolidation in the seed industry while failing to genuinely engage with the potential of alternatives to support social goods such as food security, adaptability, and resilience. The dominant IPR also constrains collaborative and cumulative plant breeding processes that are built upon the work of countless farmers past and present. Given the likely limits of current IPR, we propose that social goods in agriculture may be better supported by alternative approaches, warranting a rapid move away from the dominant single-dimensional focus on encouraging innovation through ensuring monopoly profits to IPP holders

Comparison of diurnal variations, gestational age and gender related differences in fetal heart rate (FHR) parameters between appropriate-for-gestational-age (AGA) and small-for-gestational-age (SGA) fetuses in the home environment

Objective To assess the influence of gender, time of the day and gestational age on fetal heart rate (FHR) parameters between appropriate-for-gestational-age (AGA) and small-for-gestational age (SGA) fetuses using a portable fetal ECG monitor employed in the home setting. Methods We analysed and compared the antenatal FHR data collected in the home setting on 61 healthy pregnant women with singleton pregnancies from 24 weeks gestation. Of the 61 women, 31 had SGA fetuses (estimated fetal weight below the tenth gestational centile) and 30 were pregnant with AGA fetuses. FHR recordings were collected for up to 20 h. Two 90 min intervals were deliberately chosen retrospectively with respect to signal recording quality, one during day-time and one at night-time for comparison. Results Overall, success rate of the fetal abdominal ECG in the AGA fetuses was 75.7% compared to 48.6% in the SGA group. Based on randomly selected episodes of heart rate traces where recording quality exceeded 80% we were able to show a marginal difference between day and night-time recordings in AGA vs. SGA fetuses beyond 32 weeks of gestation. A selection bias in terms of covering different representation periods of fetal behavioural states cannot be excluded. In contrast to previous studies, we neither controlled maternal diet and activity nor measured maternal blood hormone and heart rate as all mothers were monitored in the home environment. Conclusion Based on clinically unremarkable, but statistically significant differences in the FHR parameters between the AGA and SGA group we suggest that further studies with large sample size are required to assess the clinical value of antenatal fetal ECG monitoring

Is short-term-variation of fetal-heart-rate a better predictor of fetal acidaemia in labour? A feasibility study

Background Continuous intrapartum fetal monitoring is challenging and its clinical benefits are debated. The project evaluated whether short-term-variation (STV) and other computerised fetal heart rate (FHR) parameters (baseline FHR, long-term-variation, accelerations and decelerations) predicted acidaemia at birth. The aims of the study were to assess the changes in FHR pattern during labour and determine the feasibility of undertaking a definitive trial by reporting the practicalities of using the monitoring device, participant recruitment, data collection and staff training. Methods 200 high-risk women carrying a term singleton, non-anomalous fetus, requiring continuous FHR monitoring in labour were consented to participate from the Jessop Wing maternity unit, Sheffield, UK. The trans-abdominal fetal ECG monitor was placed as per clinical protocol. During the monitoring session, clinicians were blinded to the computerised FHR parameters. We analysed the last hour of the FHR and its ability to predict umbilical arterial blood pH <7.20 using receiver operator characteristics (ROC) curves. Results Of 200 women, 137 cases were excluded as either the monitor did not work from the onset of labour (n = 30), clinical staff did not return or used the monitor on another patient (n = 37), umbilical cord blood not obtained (n = 25), FHR data not recorded within an hour of birth (n = 34) and other reasons (n = 11). In 63 cases included in the final analysis, the computer-derived FHR parameters did not show significant correlation with umbilical artery cord pH <7.20. Labour was associated with a significant increase in short and long term variation of FHR and number of deceleration (P<0.001). However, baseline FHR decreased significantly before delivery (P<0.001). Conclusions The project encountered a number of challenges, with learning points crucial to informing the design of a large study to evaluate the potential place of intrapartum computerised FHR parameters, using abdominal fetal ECG monitor before its clinical utility and more widespread adoption can be ascertained