Carbenic nitrile imines: Properties and reactivity

Structures and properties of nitrile imines were investigated computationally at B3LYP and CCSD(T) levels. Whereas NBO analysis at the B3LYP DFT level invariably predicts a propargylic electronic structure, CCSD(T) calculations permit a clear distinction between propargylic, allenic, and carbenic structures. Nitrile imines with strong IR absorptions above ca. 2150 cm-1 have propargylic structures with a CN triple bond (RCNNSiMe 3 and R2BCNNBR2), and those with IR absorptions below ca. 2150 cm-1 are allenic (HCNNH, PhCNNH, and HCNNPh). Nitrile imines lacking significant cumulenic IR absorptions at 1900-2200 cm -1 are carbenic (R-(C:)-N=N-R′). Electronegative but lone pair-donating groups NR2, OR, and F stabilize the carbenic form of nitrile imines in the same way they stabilize "normal" singlet carbenes, including N-heterocyclic carbenes. NBO analyses at the CCSD(T) level confirm the classification into propargylic, allenic, and carbenic reactivity types. Carbenic nitrile imines are predicted to form azoketenes 21 with CO, to form [2+2] and [2+4] cycloadducts and borane adducts, and to cyclize to 1H-diazirenes of the type 24 in mildly exothermic reactions with activation energies in the range 29-38 kcal/mol. Such reactions will be readily accessible photochemically and thermally, e.g., under the conditions of matrix photolysis and flash vacuum thermolysis

Linear and nonlinear optical properties of a series of Ni-dithiolene derivatives

Some linear and nonlinear optical (NLO) properties of Ni(SCH)4 and several of its derivatives have been computed by employing a series of basis sets and a hierarchy of methods (e.g., HF, DFT, coupled cluster, and multiconfigurational techniques). The electronic structure of Ni(SCH)4 has been also analyzed by using CASSCF/CASPT2, ab initio valence bond, and DFT methods. In particular we discuss how the diradicaloid character (DC) of Ni(SCH)4 significantly affects its NLO properties. The quasidegeneracy of the two lowest-energy singlet states 1 mathg and 1 math1u, the clear DC nature of the former, and the very large number of low-lying states enhance the NLO properties values. These particular features are used to interpret the NLO properties of Ni(SCH)4. The DC of the considered derivatives has been estimated and correlated with the NLO properties. CASVB computations have shown that the structures with Ni(II) are the dominant ones, while those with Ni(0) and Ni(IV) have negligible weight. The weights of the four diradical structures were discussed in connection with the weight of the structures, where all the electrons are paired. Comparative discussion of the properties of Ni(SCH)4 with those of tetrathia fulvalene demonstrates the very large effect of Ni on the properties of the Ni-dithiolene derivatives. A similar remarkable effect on the NLO properties is produced by one or two methyl or C3S groups. The considered Ni-dithiolene derivatives have exceptionally large NLO properties. This feature in connection with their other physical properties makes them ideal candidates for photonic [email protected]

Monitoring complex integrated crop-livestock systems at regional scale in Brazil: a big earth observation data approach.

Due to different combinations of agriculture, livestock and forestry managed by rotation, succession and intercropping practices, integrated agriculture production systems such as integrated crop-livestock systems (iCL) constitute a very complex target and a challenge for automatic mapping of cropping practices based on remote sensing data. The overall objective of this study was to develop a classification strategy for the annual mapping of integrated Crop-Livestock systems (iCL) at a regional scale. This strategy was designed and tested in the six agro-climatic regions of Mato Grosso, the largest Brazilian soybean producer state, using MODIS satellite time-series images acquired between 2012 and 2019, ground data with heterogeneous distribution in space and time and a Random Forest classifier. The results showed that: 1. the use of unbalanced training samples with a class composition close to the real one was the right classifier training strategy; 2. the use of a single training database (pooling samples from different years and regions) to classify each region and year individually proved to be robust enough to provide similar classification accuracies in comparison to those based on the use of a database acquired for each region and for each year. The final hierarchical classification overall accuracy was 0.89 for Level 1, the cropping pattern level (single and double crops DC); 0.84 for Level 2, the DC category level (integrated system iCL soy-pasture/brachiaria, soy-cotton and soy-cereal); 0.77 for Level 3, the iCL level (iCL1 soy-pasture and iCL2 soy-pasture mixed with corn). The F-scores for DC, iCL and iCL1 cropping systems presented high accuracy (0.89, 0.85 and 0.84), while iCL2 was more difficult to classify (0.63). This approach will next be applied across the entire Brazilian soybean corridor, leading to an operational tool for monitoring the adoption of sustainable intensification practices recognized by Brazil's Agriculture Low Carbon Plan (ABC PLAN)

Chronology of prescribing error during the hospital stay and prediction of pharmacist's alerts overriding: a prospective analysis

<p>Abstract</p> <p>Background</p> <p>Drug prescribing errors are frequent in the hospital setting and pharmacists play an important role in detection of these errors. The objectives of this study are (1) to describe the drug prescribing errors rate during the patient's stay, (2) to find which characteristics for a prescribing error are the most predictive of their reproduction the next day despite pharmacist's alert (<it>i.e</it>. override the alert).</p> <p>Methods</p> <p>We prospectively collected all medication order lines and prescribing errors during 18 days in 7 medical wards' using computerized physician order entry. We described and modelled the errors rate according to the chronology of hospital stay. We performed a classification and regression tree analysis to find which characteristics of alerts were predictive of their overriding (<it>i.e</it>. prescribing error repeated).</p> <p>Results</p> <p>12 533 order lines were reviewed, 117 errors (errors rate 0.9%) were observed and 51% of these errors occurred on the first day of the hospital stay. The risk of a prescribing error decreased over time. 52% of the alerts were overridden (<it>i.e </it>error uncorrected by prescribers on the following day. Drug omissions were the most frequently taken into account by prescribers. The classification and regression tree analysis showed that overriding pharmacist's alerts is first related to the ward of the prescriber and then to either Anatomical Therapeutic Chemical class of the drug or the type of error.</p> <p>Conclusions</p> <p>Since 51% of prescribing errors occurred on the first day of stay, pharmacist should concentrate his analysis of drug prescriptions on this day. The difference of overriding behavior between wards and according drug Anatomical Therapeutic Chemical class or type of error could also guide the validation tasks and programming of electronic alerts.</p

Multi-messenger astrophysics with THESEUS in the 2030s

Multi-messenger astrophysics is becoming a major avenue to explore the Universe, with the potential to span a vast range of redshifts. The growing synergies between different probes is opening new frontiers, which promise profound insights into several aspects of fundamental physics and cosmology. In this context, THESEUS will play a central role during the 2030s in detecting and localizing the electromagnetic counterparts of gravitational wave and neutrino sources that the unprecedented sensitivity of next generation detectors will discover at much higher rates than the present. Here, we review the most important target signals from multi-messenger sources that THESEUS will be able to detect and characterize, discussing detection rate expectations and scientific impact