Anomeric and mesoneric effects in methoxycarbonylsulfenyl chloride, CH3OC(O)SCl. An experimental and theoretical study

The molecular structure and conformational properties of methoxycarbonylsulfenyl chloride, CH3OC(O)SCl, were determinated in the gas and solid phases by gas electron diffraction, low-temperature X-ray diffraction, and vibrational spectroscopy. Furthermore, quantum chemical calculations were performed. Experimental and theoretical methods result in structures with a planar C−O−C(O)−S−Cl skeleton. The electron diffraction intensities are reproduced best with a mixture of 72(8)% syn and 28(8)% anti conformers (S−Cl bond synperiplanar/antiperiplanar with respect to CdO bond) and the O−CH3 bond synperiplanar with respect to the CdO bond. The syn form is the preferred form and becomes the exclusive form in the crystalline solid at low temperature. This experimental result is reproduced very well by Hartree−Fock approximation and by density functional theory at different levels of theory but not by the MP2/6-311G* method, which overestimates the value of ∆G° between the syn and anti conformers. The results are discussed in terms of anomeric effects and a natural bond orbital (NBO) calculation. Photolysis of matrixisolated CH3OC(O)SCl with broad-band UV−visible irradiation produces an interconversion of the conformers, and the concomitant decomposition leads to formation of OCS and CO molecules.Fil: Erben, Mauricio Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Della Vedova, Carlos Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Romano, Rosana Mariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Boese, Roland. Universitat Essen; AlemaniaFil: Oberhammer, Heinz. Eberhard Karls Universität Tübingen; AlemaniaFil: Willner, Helge. Universitat Essen; AlemaniaFil: Sala, Oswaldo. Universidade de Sao Paulo; Brasi

Effect of the SARS-CoV-2 pandemic on colorectal cancer diagnosis and prognosis

COVID-19 pandemic; Endoscopy; Screening colonoscopyPandèmia COVID-19; Endoscòpia; Colonoscòpia de cribratgePandemia COVID-19; Endoscopia; Colonoscopia de cribadoBackground and Study Aims Our aim was to determine the impact of the SARS-CoV-2 pandemic on the diagnosis and prognosis of colorectal cancer (CRC). Patients and Methods This prospective cohort study included individuals diagnosed with CRC between March 13, 2019 and June 20, 2021 across 21 Spanish hospitals. Two time periods were compared: prepandemic (from March 13, 2019 to March 13, 2020) and pandemic (from March 14, 2020 to June 20, 2021, lockdown period and 1 year after lockdown). Results We observed a 46.9% decrease in the number of CRC diagnoses (95% confidence interval (CI): 45.1%–48.7%) during the lockdown and 29.7% decrease (95% CI: 28.1%–31.4%) in the year after the lockdown. The proportion of patients diagnosed at stage I significantly decreased during the pandemic (21.7% vs. 19.0%; p = 0.025). Centers that applied universal preprocedure SARS-CoV-2 PCR testing experienced a higher reduction in the number of colonoscopies performed during the pandemic post-lockdown (34.0% reduction; 95% CI: 33.6%–34.4% vs. 13.7; 95% CI: 13.4%–13.9%) and in the number of CRCs diagnosed (34.1% reduction; 95% CI: 31.4%–36.8% vs. 26.7%; 95% CI: 24.6%–28.8%). Curative treatment was received by 87.5% of patients diagnosed with rectal cancer prepandemic and 80.7% of patients during the pandemic post-lockdown period (p = 0.002). Conclusions The COVID-19 pandemic has led to a decrease in the number of diagnosed CRC cases and in the proportion of stage I CRC. The reduction in the number of colonoscopies and CRC diagnoses was higher in centers that applied universal SARS-CoV-2 PCR screening before colonoscopy. In addition, the COVID-19 pandemic has affected curative treatment of rectal cancers.This work was supported by ISABIAL UPG-20-096 grant and Instituto de Salud Carlos III (PI20/01527), Asociación para la Investigación en Gastroenterología de la Provincia de Alicante (AIGPA), a private association that promotes research in gastrointestinal diseases in Alicante, supported the logistical aspects of the study. This association declare no conflicts of interest

Role of Artificial Intelligence in Colonoscopy Detection of Advanced Neoplasias. A Randomized Trial.

Background: The role of computer-aided detection in identifying advanced colorectal neoplasia is unknown. Objective: To evaluate the contribution of computer-aided detection to colonoscopic detection of advanced colorectal neoplasias as well as adenomas, serrated polyps, and nonpolypoid and right-sided lesions. Design: Multicenter, parallel, randomized controlled trial. (ClinicalTrials.gov: NCT04673136) Setting: Spanish colorectal cancer screening program. Participants: 3213 persons with a positive fecal immunochemical test. Intervention: Enrollees were randomly assigned to colonoscopy with or without computer-aided detection. Measurements: Advanced colorectal neoplasia was defined as advanced adenoma and/or advanced serrated polyp. Results: The 2 comparison groups showed no significant difference in advanced colorectal neoplasia detection rate (34.8% with intervention vs. 34.6% for controls; adjusted risk ratio [aRR], 1.01 [95% CI, 0.92 to 1.10]) or the mean number of advanced colorectal neoplasias detected per colonoscopy (0.54 [SD, 0.95] with intervention vs. 0.52 [SD, 0.95] for controls; adjusted rate ratio, 1.04 [99.9% CI, 0.88 to 1.22]). Adenoma detection rate also did not differ (64.2% with intervention vs. 62.0% for controls; aRR, 1.06 [99.9% CI, 0.91 to 1.23]). Computer-aided detection increased the mean number of nonpolypoid lesions (0.56 [SD, 1.25] vs. 0.47 [SD, 1.18] for controls; adjusted rate ratio, 1.19 [99.9% CI, 1.01 to 1.41]), proximal adenomas (0.94 [SD, 1.62] vs. 0.81 [SD, 1.52] for controls; adjusted rate ratio, 1.17 [99.9% CI, 1.03 to 1.33]), and lesions of 5 mm or smaller (polyps in general and adenomas and serrated lesions in particular) detected per colonoscopy. Limitations: The high adenoma detection rate in the control group may limit the generalizability of the findings to endoscopists with low detection rates. Conclusion: Computer-aided detection did not improve colonoscopic identification of advanced colorectal neoplasias. Primary Funding Source: Medtronic

Hotspots of biogeochemical activity linked to aridity and plant traits across global drylands

14 páginas.- 4 figuras.- 67 referencias.- The online version contains supplementary material available at https://doi.org/10.1038/s41477-024-01670-7Perennial plants create productive and biodiverse hotspots, known as fertile islands, beneath their canopies. These hotspots largely determine the structure and functioning of drylands worldwide. Despite their ubiquity, the factors controlling fertile islands under conditions of contrasting grazing by livestock, the most prevalent land use in drylands, remain virtually unknown. Here we evaluated the relative importance of grazing pressure and herbivore type, climate and plant functional traits on 24 soil physical and chemical attributes that represent proxies of key ecosystem services related to decomposition, soil fertility, and soil and water conservation. To do this, we conducted a standardized global survey of 288 plots at 88 sites in 25 countries worldwide. We show that aridity and plant traits are the major factors associated with the magnitude of plant effects on fertile islands in grazed drylands worldwide. Grazing pressure had little influence on the capacity of plants to support fertile islands. Taller and wider shrubs and grasses supported stronger island effects. Stable and functional soils tended to be linked to species-rich sites with taller plants. Together, our findings dispel the notion that grazing pressure or herbivore type are linked to the formation or intensification of fertile islands in drylands. Rather, our study suggests that changes in aridity, and processes that alter island identity and therefore plant traits, will have marked effects on how perennial plants support and maintain the functioning of drylands in a more arid and grazed world.This research was supported by the European Research Council (ERC grant 647038 (BIODESERT) awarded to F.T.M.) and Generalitat Valenciana (CIDEGENT/2018/041). D.J.E. was supported by the Hermon Slade Foundation (HSF21040). J. Ding was supported by the National Natural Science Foundation of China Project (41991232) and the Fundamental Research Funds for the Central Universities of China. M.D.-B. acknowledges support from TED2021-130908B-C41/AEI/10.13039/501100011033/Unión Europea Next Generation EU/PRTR and the Spanish Ministry of Science and Innovation for the I + D + i project PID2020-115813RA-I00 funded by MCIN/AEI/10.13039/501100011033. O.S. was supported by US National Science Foundation (Grants DEB 1754106, 20-25166), and Y.L.B.-P. by a Marie Sklodowska-Curie Actions Individual Fellowship (MSCA-1018 IF) within the European Program Horizon 2020 (DRYFUN Project 656035). K.G. and N.B. acknowledge support from the German Federal Ministry of Education and Research (BMBF) SPACES projects OPTIMASS (FKZ: 01LL1302A) and ORYCS (FKZ: FKZ01LL1804A). B.B. was supported by the Taylor Family-Asia Foundation Endowed Chair in Ecology and Conservation Biology, and M. Bowker by funding from the School of Forestry, Northern Arizona University. C.B. acknowledges funding from the National Natural Science Foundation of China (41971131). D.B. acknowledges support from the Hungarian Research, Development and Innovation Office (NKFI KKP 144096), and A. Fajardo support from ANID PIA/BASAL FB 210006 and the Millennium Science Initiative Program NCN2021-050. M.F. and H.E. received funding from Ferdowsi University of Mashhad (grant 39843). A.N. and M.K. acknowledge support from FCT (CEECIND/02453/2018/CP1534/CT0001, SFRH/BD/130274/2017, PTDC/ASP-SIL/7743/2020, UIDB/00329/2020), EEA (10/CALL#5), AdaptForGrazing (PRR-C05-i03-I-000035) and LTsER Montado platform (LTER_EU_PT_001) grants. O.V. acknowledges support from the Hungarian Research, Development and Innovation Office (NKFI KKP 144096). L.W. was supported by the US National Science Foundation (EAR 1554894). Y.Z. and X.Z. were supported by the National Natural Science Foundation of China (U2003214). H.S. is supported by a María Zambrano fellowship funded by the Ministry of Universities and European Union-Next Generation plan. The use of any trade, firm or product names does not imply endorsement by any agency, institution or government. Finally, we thank the many people who assisted with field work and the landowners, corporations and national bodies that allowed us access to their land.Peer reviewe

Uma introdução à espectroscopia atômica: II - o espectro do sódio An introduction to atomic spectroscopy: II - the sodium spectrum

<abstract language="eng">The present article is devoted to Chemistry or Physics undergraduate students, given their difficulty to understand fundamental concepts and technical language used in atomic spectroscopy and quantum mechanics. An easy approach is shown in the treatment of the emission spectrum of the sodium atom without any involved calculations. In a previous article, the hydrogen spectrum was considered and the energy degeneracy of the angular momentum quantum number was observed. For the sodium spectrum, due to the valence electron penetration into internal shells, a breakdown of this degeneracy occurs and a dependence of this penetration on the angular momentum quantum number is observed. The eigenvalues are determined introducing the quantum defect correction (Rydberg correction) in the denominator of the Balmer equation, and the energy diagram is obtained. The intensity ratio for the observed doublets is explained by introducing new wave functions, containing the magnetic quantum number of the total angular momentum

I2: uma molécula didática I2: a pedagogical molecule

<abstract language="eng">Iodine vapor is a very suitable substance to learn about molecular energy levels and transitions, and to introduce spectroscopic techniques. As a diatomic molecule its spectra are relatively simple and allow straightforward treatment of the data leading to the potential energy curves and to quantum mechanics concepts. The overtone bands, in the resonance Raman scattering, and the band progressions, in the electronic spectra, play an important role in the calculation of the Morse potential curves for the fundamental and excited electronic state. A weaker chemical bond in the electronic excited state, compared to the fundamental state, is evidenced by the increase in the equilibrium interatomic distance. The resonance Raman scattering of I2 is highlighted due to its importance for obtaining the anharmonicity constant in the fundamental electronic state

Uma introdução à espectroscopia atômica: o átomo de hidrogênio An introduction to atomic spectroscopy: the hydrogen atom

<abstract language="eng">The Balmer equation is obtained from the hydrogen spectrum in an empirical way, using a graphic method; from this equation the energy level terms are derived. Emphasis is given to concepts in order to make clear the meaning of quantum numbers, eigenvalues and eigenfunctions in the Schrödinger equation