Stabilization of Diborynes versus Destabilization of Diborenes by Coordination of Lewis Bases: Unravelling the Dichotomy.

We have quantum chemically investigated the boron-boron bonds in B2 , diborynes B2 L2 , and diborenes B2 H2 L2 (L=none, OH2 , NH3 ) using dispersion-corrected relativistic density functional theory at ZORA-BLYP-D3(BJ)/TZ2P. B2 has effectively a single B-B bond provided by two half π bonds, whereas B2 H2 has effectively a double B=B bond provided by two half π bonds and one σ 2p-2p bond. This different electronic structure causes B2 and B2 H2 to react differently to the addition of ligands. Thus, in B2 L2 , electron-donating ligands shorten and strengthen the boron-boron bond whereas, in B2 H2 L2 , they lengthen and weaken the boron-boron bond. The aforementioned variations in boron-boron bond length and strength become more pronounced as the Lewis basicity of the ligands L increases.

Beryllium compounds for the carbon-halogen bond activation of phenyl halides: the role of non-innocent ligands.

Beryllium is a metallomimetic main-group element, i.e., it behaves similarly to transition metals (TMs) in some bond activation processes. To investigate the ability of Be compounds to activate C-X bonds (X = F-I), we have computationally investigated, using DFT methods, the reaction of (CAAC)2Be (CAAC = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) and a series of five-membered heterocyclic beryllium bidentate ligands with phenyl halides. We have analysed all plausible reaction mechanisms and our results show that, after the initial C-X oxidative addition, migration of the phenyl group occurs towards the less electronegative heteroatom. Our theoretical study highlights the important role of bidentate non-innocent ligands in providing the required electrons for the initial Ph-X oxidative addition. In contrast, the monodentate ligand, CAAC, does not favour this oxidative addition.

Diagnósticos frecuentes de consulta externa de medicina general de la Universidad Santo Tomás (USTA), Bucaramanga, 2015-2017 / Frequent diagnosis in primary care physician services of the Santo Tomás University (USTA), Bucaramanga, 2015-2017

RESUMEN Objetivo Determinar los diagnósticos más frecuentes de los pacientes atendidos en el servicio de consulta externa de medicina general de la Universidad Santo Tomás (USTA), seccional Bucaramanga, entre 2015 y 2017. Método Estudio descriptivo retrospectivo de los registros diarios de pacientes atendidos en el servicio médico con un N=13 892 pacientes -estudiantes, administrativos, docentes, egresados y División de Educación Abierta y a Distancia (DUAD)-. Se excluyeron 5 907 registros para un n=7 985 datos de exploración, correspondientes a pacientes que hicieron uso exclusivamente del servicio de consulta médica. Resultados 5 808 (73%) de las consultas fueron realizadas por mujeres y 2 177 (27%) hombres; jóvenes entre 19 y 26 años (60,9%), estudiantes de pregrado (71,8%), de odontología (29,6%) y derecho (26,5%), atendidos por enfermedades del aparato respiratorio (16,4%), con afectaciones más frecuentes a adolescentes (15,4%) y jóvenes (17,2%). La rinofaringitis aguda fue el principal diagnóstico CIE-10. Los jóvenes consultaron por diarrea y gastroenteritis de presunto origen infeccioso (6,7%); los adultos (5,7%) y docentes (6,1%), por cervicalgia, y el personal administrativo, por infección viral no especificada (5,7%). Conclusiones La población atendida en consulta médica de la USTA entre 2015 y 2017 fueron principalmente mujeres y jóvenes entre 19 a 26 años. Las enfermedades transmisibles como las enfermedades del aparato respiratorio fueron más frecuentes que las enfermedades crónicas no transmisibles, principalmente la rinofaringitis aguda, enfermedad de alta transmisibilidad en comunidad. Las mujeres, adolescentes y estudiantes de pregrado, fueron atendidos en consulta por consejo y asesoramiento sobre la anticoncepción, lo que coincide con la Encuesta Nacional De Demografía y Salud.

ABSTRACT Objective To determine the most frequent diagnoses of the patients treated in primary medical care services of the Santo Tomás University (USTA, by its initials in Spanish), Bucaramanga section, between 2015 and 2017. Method A retrospective descriptive study of the daily records of patients treated in primary medical care services with an N=13 892 patients -students, administrative workers, professors, graduates, and Open and at Distance Education Division (DUAD, by its initials in Spanish)-. 5 907 records were excluded for a n=7 985 scan data corresponding to patients who used the medical consultation service exclusively. Results 5 808 (73%) of the consultations were conducted by women and 2 177 (27%) by men; young people between 19 and 26 years (60.9%), undergraduate students (71.8%), in dentistry (29.6%) and law (26.5%), people treated for respiratory diseases (16.4%), affected adolescents (15.4%) and young people (17.2%) more frequently. Acute rhinopharyngitis was the main diagnosis ICD-10. Young people consulted for diarrhea and gastroenteritis of suspected infectious origin (6.7%); adults (5.7%) and professors (6.1%), for neck pain, and administrative workers, for unspecified viral infection (5.7%). Conclusions The population who attended medical consultation of the Santo Tomás University in Bucaramanga throughout 2015-2017 were mainly women and young people between 19 and 26 years. Communicable diseases such as respiratory diseases were more frequent than chronic noncommunicable diseases, mainly acute rhinopharyngitis, a disease of high transmissibility in the community. Women, adolescents, and undergraduate students were treated in consultation for contraceptive counseling, which coincides with the National Demography and Health Survey.

The Diaryliodonium(III) Salts Reaction With Free-Radicals Enables One-Pot Double Arylation of Naphthols.

The chemoselective reaction of the C- followed by the O-centered naphthyl radicals with the more electron-deficient hypervalent bond of the diaryliodonium(III) salts is described. This discovered reactivity constitutes a new activation mode of the diaryliodonium(III) salts which enabled a one-pot doubly arylation of naphthols through the sequential C s p 2 - C s p 2 /O- C s p 2 bond formation. The naphthyl radicals were generated in the reaction by the tetramethylpiperidinyl radical (TMP·) which resulted from the homolytic fragmentation of the precursor TMP2O. Experimental and DFT calculations provided a complete panorama of the reaction mechanism.

Trapping of a Borirane Intermediate in the Reductive Coupling of an Arylborane to a Diborene.

The reductive coupling of a N-heterocyclic carbene (NHC)-stabilized aryldibromoborane yields a mixture of trans- and cis-diborenes in which the aryl groups are coplanar with the diborene core. Under dilute reduction conditions two diastereomers of a borirane-borane intermediate are isolated, which upon further reduction give rise to the aforementioned diborene mixture. DFT calculations suggest a mechanism proceeding via nucleophilic attack of a dicoordinate borylene intermediate on the aryl ring and subsequent intramolecular B-B bond formation.

Metales pesados en el ambiente: síndrome de Guillain-Barré / likeHeavy metals in the enviroment: Guillain-Barré like syndrome

El síndrome de Guillain-Barré constituye una entidad de etiología diversa, que se caracteriza por debilidad muscular aguda, simétrica, ascendente y progresiva, y es una de las polineuropatías adquiridas más frecuentes en la infancia. Entre los diagnósticos diferenciales, deben considerarse las neuropatías producidas por metales pesados, mercurio y plomo, y metaloides, como el arsénico, plaguicidas organofosforados y el tetracloruro de carbono.Se presenta a un paciente de 14 años con diagnóstico de síndrome de Guillain-Barré sin respuesta al tratamiento convencional con gammaglobulina. Considerando otras etiologías, se sospechó neuropatía producida por metales pesados, y se confirmó intoxicación por mercurio.El objetivo de esta presentación es concientizar a los pediatras acerca del impacto de los tóxicos ambientales en la salud infantil para realizar un diagnóstico precoz pesquisando datos clave a través de la historia clínica ambiental

Guillain-Barré syndrome is an entity of diverse etiology, characterized by acute, symmetric, ascending and progressive muscle weakness, being one of the most frequent acquired polyneuropathies in childhood. Neuropathies produced by heavy metals, mercury and lead, and metalloids, such as arsenic, organophosphorus pesticides and carbon tetrachloride, should be considered among the differential diagnoses.We present a 14-year-old patient with a presumptive diagnosis of Guillain-Barré syndrome without response to conventional treatment with gamma globulin. Considering other etiologies, heavy metal neuropathy was suspected, and mercury poisoning was confirmed.The aim of this presentation is to make pediatricians aware about the impact of environmental toxic agents on children's health in order to make an early diagnosis by researching key data through the environmental clinical history.

[Heavy metals in the enviroment: Guillain-Barre like syndrome]. / Metales pesados en el ambiente: smdrome de Gmllam-Barre like.

Guillain-Barré syndrome is an entity of diverse etiology, characterized by acute, symmetric, ascending and progressive muscle weakness, being one of the most frequent acquired polyneuropathies in childhood. Neuropathies produced by heavy metals, mercury and lead, and metalloids, such as arsenic, organophosphorus pesticides and carbon tetrachloride, should be considered among the differential diagnoses. We present a 14-year-old patient with a presumptive diagnosis of Guillain-Barré syndrome without response to conventional treatment with gamma globulin. Considering other etiologies, heavy metal neuropathy was suspected, and mercury poisoning was confirmed. The aim of this presentation is to make pediatricians aware about the impact of environmental toxic agents on children's health in order to make an early diagnosis by researching key data through the environmental clinical history.

El síndrome de Guillain-Barré constituye una entidad de etiología diversa, que se caracteriza por debilidad muscular aguda, simétrica, ascendente y progresiva, y es una de las polineuropatías adquiridas más frecuentes en la infancia. Entre los diagnósticos diferenciales, deben considerarse las neuropatías producidas por metales pesados, mercurio y plomo, y metaloides, como el arsénico, plaguicidas organofosforados y el tetracloruro de carbono. Se presenta a un paciente de 14 años con diagnóstico de síndrome de Guillain-Barré sin respuesta al tratamiento convencional con gammaglobulina. Considerando otras etiologías, se sospechó neuropatía producida por metales pesados, y se confirmó intoxicación por mercurio. El objetivo de esta presentación es concientizar a los pediatras acerca del impacto de los tóxicos ambientales en la salud infantil para realizar un diagnóstico precoz pesquisando datos clave a través de la historia clínica ambiental.

Valores de referencia pediátricos de cromo y mercurio en orina del área de la Ciudad de Buenos Aires y alrededores / Pediatric reference values for chromium and mercury in urine in the City of Buenos Aires and Greater Buenos Aires

Introducción. Debido a la fuerte industrialización de la Ciudad de Buenos Aires y alrededores, la población podría estar expuesta a metales. Para poder evaluar el nivel de exposición de los niños al cromo y al mercurio, es fundamental tener valores de referencia (VR) propios. El objetivo fue determinar los VR pediátricos para cromo y mercurio en la muestra aislada de orina. Población y métodos: Se incluyeron niños y niñas no expuestos a los contaminantes evaluados que concurrieron al Servicio de Bajo Riesgo y al Consultorio del Jardín Maternal del Hospital de Pediatría S.A.M.I.C. "Prof. Dr. Juan P. Garrahan". Se cuantificó cromo (UCr), mercurio (UHg) y creatinina urinarios. Se calcularon los p95 con su intervalo de confianza del 95 % [IC 95 %] según el concepto para VR de la German Human Biomonitoring Commission. Resultados: Se incluyeron 160 pacientes en el estudio. Se obtuvieron 144 muestras de niños y niñas de entre 1 y 17 años (mediana: 7 años). Se cuantificó UCr a 137 muestras y UHg a 129. La mediana y rango de cromo fue 0,54 (indetectable -3,06) µg/g de creatinina y la de mercurio fue 0,49 (indetectable -7,57) µg/g de creatinina.Conclusiones: Los VR fueron, para UCr, hasta 1,5 µg/l [1,2-2,8] y hasta 2,2 µg/g de creatinina [1,8-3,0] y para UHg, hasta 2,5 µg/l [1,8-4,8] y 3,2 µg/g de creatinina [2,5-4,7

Introduction. Due to the heavy industrialization of the Autonomous City of Buenos Aires and Greater Buenos Aires, the population may have become exposed to metals.To assess the level of exposure to chromium and mercury in children, it is critical to have local reference values (RVs). Our objective was to determine pediatric RVs for chromium and mercury in a single urine sample.Population and methods: Children who were not exposed to the studied contaminants and who attended the Department of Low Risk Conditions and the Daycare Center Office of Hospital de Pediatría S.A.M.I.C. "Prof. Dr. Juan P. Garrahan" were included. Urinary chromium (UCr), urinary mercury (UHg), and urinary creatinine were measured. The p95 and its corresponding 95 % confidence interval (CI) were estimated based on the RV concept proposed by the German Human Biomonitoring Commission.Results: The study included 160 patients. A total of 144 samples from children aged 1-17 years (median: 7 years) were collected. UCr was measured in 137 samples and UHg, in 129 samples. The median value of chromium was 0.54 µg/g of creatinine (range, undetectable to 3.06), while that of mercury was 0.49 µg/g of creatinine (range, undetectable to 7.57). Conclusions: The RVs for UCr were up to 1.5 µg/L [1.2-2.8] and up to 2.2 µg/g of creatinine [1.8-3.0], and for UHg, up to 2.5 µg/L [1.8-4.8] and 3.2 µg/g of creatinine [2.5-4.7]

Pediatric reference values for chromium and mercury in urine in the City of Buenos Aires and Greater Buenos Aires. / Valores de referencia pediátricos de cromo y mercurio en orina del área de la Ciudad de Buenos Aires y alrededores.

INTRODUCTION: Due to the heavy industrialization of the Autonomous City of Buenos Aires and Greater Buenos Aires, the population may have become exposed to metals. To assess the level of exposure to chromium and mercury in children, it is critical to have local reference values (RVs). Our objective was to determine pediatric RV s for chromium and mercury in a single urine sample. POPULATION AND METHODS: Children who were not exposed to the studied contaminants and who attended the Department of Low Risk Conditions and the Daycare Center Office of Hospital de Pediatría S.A.M.I.C. "Prof. Dr. Juan P. Garrahan" were included. Urinary chromium (UCr), urinary mercury (UHg), and urinary creatinine were measured. The p95 and its corresponding 95 % confidence interval (CI) were estimated based on the RV concept proposed by the German Human Biomonitoring Commission. RESULTS: The study included 160 patients. A total of 144 samples from children aged 1-17 years (median: 7 years) were collected. UCr was measured in 137 samples and UHg, in 129 samples. The median value of chromium was 0.54 µg/g of creatinine (range, undetectable to 3.06), while that of mercury was 0.49 µg/g of creatinine (range, undetectable to 7.57). CONCLUSIONS: The RVs for UCr were up to 1.5 µg/L [1.2-2.8] and up to 2.2 µg/g of creatinine [1.8-3.0], and for UHg, up to 2.5 µg/L [1.8-4.8] and 3.2 µg/g of creatinine [2.5-4.7].

Introducción. Debido a la fuerte industrialización de la Ciudad de Buenos Aires y alrededores, la población podría estar expuesta a metales. Para poder evaluar el nivel de exposición de los niños al cromo y al mercurio, es fundamental tener valores de referencia (VR) propios. El objetivo fue determinar los VR pediátricos para cromo y mercurio en la muestra aislada de orina. Población y métodos: Se incluyeron niños y niñas no expuestos a los contaminantes evaluados que concurrieron al Servicio de Bajo Riesgo y al Consultorio del Jardín Maternal del Hospital de Pediatría S. A. M. I. C. "Prof. Dr. Juan P. Garrahan". Se cuantificó cromo (UCr), mercurio (UHg) y creatinina urinarios. Se calcularon los p95 con su intervalo de confianza del 95 % [IC 95 %] según el concepto para VR de la German Human Biomonitoring Commission. Resultados: Se incluyeron 160 pacientes en el estudio. Se obtuvieron 144 muestras de niños y niñas de entre 1 y 17 años (mediana: 7 años). Se cuantificó UCr a 137 muestras y UHg a 129. La mediana y rango de cromo fue 0,54 (indetectable -3,06) µg/g de creatinina y la de mercurio fue 0,49 (indetectable -7,57) µg/g de creatinina. Conclusiones: Los VR fueron, para UCr, hasta 1,5 µg/l [1,2-2,8] y hasta 2,2 µg/g de creatinina [1,8-3,0] y para UHg, hasta 2,5 µg/l [1,8-4,8] y 3,2 µg/g de creatinina [2,5-4,7].

Molecular QTAIM Topology Is Sensitive to Relativistic Corrections.

The topology of the molecular electron density of benzene dithiol gold cluster complex Au4 -S-C6 H4 -S'-Au'4 changed when relativistic corrections were made and the structure was close to a minimum of the Born-Oppenheimer energy surface. Specifically, new bond paths between hydrogen atoms on the benzene ring and gold atoms appeared, indicating that there is a favorable interaction between these atoms at the relativistic level. This is consistent with the observation that gold becomes a better electron acceptor when relativistic corrections are applied. In addition to relativistic effects, here, we establish the sensitivity of molecular topology to basis sets and convergence thresholds for geometry optimization.

Fractions of aqueous and methanolic extracts from tomato (Solanum lycopersicum L.) present platelet antiaggregant activity.

Cardiovascular disease (CVD) is the leading cause of death worldwide. Its prevention emphasizes three aspects: not smoking, physical activity and a healthy diet. Recently, we screened the antithrombotic activity of a selected group of fruits and vegetables. Among them, tomato showed an important effect. The aim of this study was to evaluate and characterize the platelet antiaggregatory activity of tomato (Solanum lycopersicum L.). For this, we obtained aqueous and methanolic tomato extracts and evaluated the effect of pH (2 and 10) and temperature (22, 60 and 100°C) on this activity. Furthermore, in order to isolate the antiaggregant principle, we separated tomato extracts into several fractions (A-D) by size exclusion chromatography. In addition, we evaluated the platelet antiaggregating activity ex vivo in Wistar rats. Aqueous and methanolic extracts of tomato treated at 22, 60 and 100°C and pH 2 and 10 still inhibited platelet aggregation (in vitro). Moreover, it was noted that one of the fractions (fraction C), from both aqueous and methanolic extracts, presented the highest activity (∼70% inhibition of platelet aggregation) and concentration dependently inhibited platelet aggregation significantly compared with control (P < 0.05). These fractions did not contain lycopene but presented two peaks of absorption, at 210 and 261 nm, compatible with the presence of nucleosides. In rats treated with tomato macerates, a mild platelet antiaggregating effect ex vivo was observed. Further studies are required to identify the molecules with platelet antiaggregating activity and antiplatelet mechanisms of action.

[Chronic endemic regional hydroarsenicism: a challenge for diagnosis and prevention]. / Hidroarsenisismo crónico regional endémico: un desafío diagnóstico y de prevención.

Arsenic (As) is a semimetal that is widely distributed in nature, in water and soil. In Argentine, the contamination of both waterways and groundwater represents the main environmental problem caused by this element. Chronic As poisoning is known as Chronic endemic regional hydroarsenicism (C.E.R.HA.). Long-term exposure to low concentrations of the element from the prenatal period onward results in the well-known symptoms of chronic As poisoning. CERHA develops progressively, compromising different organs and systems, most importantly the skin. One of the most important complications of CERHA is de development of neoplasias, mainly skin tumors. Childhood environmental health is a challenge in the new millennium and health care professionals play a fundamental role in the protection against environmental hazards such as chronic arsenic poisoning.

Hidroarsenisismo crónico regional endémico: un desafío diagnóstico y de prevención / Chronic endemic regional hydroarsenicism: a challenge for diagnosis and prevention

El arsénico (As) es un semi-metal, ampliamente distribuido en la naturaleza en aguas y suelos. La contaminación de los cursos de agua, tanto superficiales como profundos, constituye el principal problema ambiental generado por este elemento. La intoxicación con As se denomina hidroarsenicismo crónico regional endémico (HACRE). Su importancia de la intoxicación crónica con As en la infancia está dada por los conocidos efectos asociados a la exposición acumulada desde el período prenatal en bajas concentraciones. El HACRE se desarrolla progresivamente, comprometiendo diversos órganos y sistemas, principalmente la piel. Una de las complicaciones más importantes del HACRE es el desarrollo de neoplasias, principalmente tumores cutáneos. El HACRE es una enfermedad prevenible. La salud ambiental infantil representa un desafío del nuevo milenio y los profesionales de la salud cumplen un rol fundamental frente a las amenazas ambientales como las que presentala intoxicación crónica con arsenico.

Arsenic (As) is a semimetal that is widely distributed in nature, in water and soil. In Argentine, the contamination of both waterways and groundwater represents the main environmental problem caused by this element. Chronic As poisoning is known as Chronic endemic regional hydroarsenicism (C.E.R.HA.). Long-term exposure to low concentrations of the element from the prenatal period onward results in the well-known symptoms of chronic As poisoning. CERHA develops progressively, compromising different organs and systems, most importantly the skin. One of the most important complications of CERHA is de development of neoplasias, mainly skin tumors. Childhood environmental health is a challenge in the new millennium and health care professionals play a fundamental role in the protection against environmental hazards such as chronic arsenic poisoning.

Hidroarsenisismo crónico regional endémico: un desafío diagnóstico y de prevención / Chronic endemic regional hydroarsenicism: a challenge for diagnosis and prevention

El arsénico (As) es un semi-metal, ampliamente distribuido en la naturaleza en aguas y suelos. La contaminación de los cursos de agua, tanto superficiales como profundos, constituye el principal problema ambiental generado por este elemento. La intoxicación con As se denomina hidroarsenicismo crónico regional endémico (HACRE). Su importancia de la intoxicación crónica con As en la infancia está dada por los conocidos efectos asociados a la exposición acumulada desde el período prenatal en bajas concentraciones. El HACRE se desarrolla progresivamente, comprometiendo diversos órganos y sistemas, principalmente la piel. Una de las complicaciones más importantes del HACRE es el desarrollo de neoplasias, principalmente tumores cutáneos. El HACRE es una enfermedad prevenible. La salud ambiental infantil representa un desafío del nuevo milenio y los profesionales de la salud cumplen un rol fundamental frente a las amenazas ambientales como las que presentala intoxicación crónica con arsenico.(AU)

Arsenic (As) is a semimetal that is widely distributed in nature, in water and soil. In Argentine, the contamination of both waterways and groundwater represents the main environmental problem caused by this element. Chronic As poisoning is known as Chronic endemic regional hydroarsenicism (C.E.R.HA.). Long-term exposure to low concentrations of the element from the prenatal period onward results in the well-known symptoms of chronic As poisoning. CERHA develops progressively, compromising different organs and systems, most importantly the skin. One of the most important complications of CERHA is de development of neoplasias, mainly skin tumors. Childhood environmental health is a challenge in the new millennium and health care professionals play a fundamental role in the protection against environmental hazards such as chronic arsenic poisoning.(AU)

Effect of framework design on crown failure.

This study evaluated the effect of core-design modification on the characteristic strength and failure modes of glass-infiltrated alumina (In-Ceram) (ICA) compared with porcelain fused to metal (PFM). Premolar crowns of a standard design (PFMs and ICAs) or with a modified framework design (PFMm and ICAm) were fabricated, cemented on dies, and loaded until failure. The crowns were loaded at 0.5 mm min(-1) using a 6.25 mm tungsten-carbide ball at the central fossa. Fracture load values were recorded and fracture analysis of representative samples were evaluated using scanning electron microscopy. Probability Weibull curves with two-sided 90% confidence limits were calculated for each group and a contour plot of the characteristic strength was obtained. Design modification showed an increase in the characteristic strength of the PFMm and ICAm groups, with PFM groups showing higher characteristic strength than ICA groups. The PFMm group showed the highest characteristic strength among all groups. Fracture modes of PFMs and of PFMm frequently reached the core interface at the lingual cusp, whereas ICA exhibited bulk fracture through the alumina core. Core-design modification significantly improved the characteristic strength for PFM and for ICA. The PFM groups demonstrated higher characteristic strength than both ICA groups combined.