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1.
Braz J Biol ; 83: e274499, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38055576

RESUMEN

Salinity is harmful to crops when the concentration of soluble salts overcomes the salinity threshold of the crop, causing osmotic stress and limitations in plant growth. In this scenario, adopting tolerant cultivars is the most adequate strategy to minimize agricultural losses. However, the inheritance of tolerance depends on the genotype. From this perspective, this study assessed the tolerance to severe salt stress in 11 cotton cultivars based on gas exchange parameters and the free proline content. The cultivars were grown in a greenhouse and subjected to 34 days of saline irrigation (10 dS m-1), starting 45 days after seedling emergence (B1 phase). Plant growth was monitored weekly until the end of the salt stress period. The treatments consisted of a combination of two factors: eleven cultivars associated with two electrical conductivity levels of irrigation water (ECw: 0.3 and 10.0 dS m-1). The experimental design was in randomized blocks in a 11 × 2 factorial arrangement with three replications (66 plots), with the experimental unit consisting of one plant per plot. Salinity impacted plant growth, being reflected on the gas exchange and free proline data of most cultivars. However, BRS 286, FMT 705, BRS 416, and BRS Acácia, and CNPA 7MH withstood the effects of stress and osmotically adjusted to the salt stress conditions, thus minimizing the damage to growth. Those cultivars are the most indicated for improvement programs aiming at tolerance to salt stress based on the results found in this research.


Asunto(s)
Estrés Salino , Tolerancia a la Sal , Plantones , Salinidad , Prolina
2.
Anal Bioanal Chem ; 413(16): 4301-4310, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33963881

RESUMEN

Marine sponges from the Plakinidae family are well known for hosting cytotoxic secondary metabolites and the Brazilian Atlantic coast and its oceanic islands have been considered as a hotspot for the discovery of new Plakinidae species. Herein, we report the chemical profile among cytotoxic extracts obtained from four species of Plakinidae, collected in Fernando de Noronha Archipelago (PE, Northeastern Brazil). Crude organic extracts of Plakinastrella microspiculifera, Plakortis angulospiculatus, Plakortis insularis, and Plakortis petrupaulensis showed strong antiproliferative effects against two different cancer cell lines (HCT-116: 86.7-100%; MCF-7: 74.9-89.5%) at 50 µg/mL, by the MTT assay. However, at a lower concentration (5 µg/mL), high variability in inhibition of cell growth was observed (HCT-116: 17.3-68.7%; MCF-7: 0.00-55.5%), even within two samples of Plakortis insularis which were collected in the west and east sides of the Archipelago. To discriminate the chemical profile, the samples were investigated by UHPLC-HRMS under positive ionization mode. The produced data was uploaded to the Global Natural Products Social Molecular Networking and organized based on spectral similarities for purposes of comparison and annotation. Compounds such as dipeptides, nucleosides and derivatives, polyketides, and thiazine alkaloids were annotated and metabolomic differences were perceived among the species. To the best of our knowledge, this is the first assessment for cytotoxic activity and chemical profiling for Plakinastrella microspiculifera, Plakortis insularis and Plakortis petrupaulensis, revealing other biotechnologically relevant members of the Plakinidae family.


Asunto(s)
Metaboloma , Poríferos/química , Animales , Antineoplásicos/química , Antineoplásicos/farmacología , Productos Biológicos/química , Productos Biológicos/farmacología , Brasil , Proliferación Celular/efectos de los fármacos , Células HCT116 , Humanos , Islas , Células MCF-7 , Metabolómica , Neoplasias/tratamiento farmacológico , Plakortis/química , Plakortis/metabolismo , Poríferos/metabolismo
3.
J Mycol Med ; 30(4): 101044, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33046394

RESUMEN

INTRODUCTION: Cryptococcus neoformans is an opportunistic pathogen that causes ∼15% mortality in AIDS patients. Rio Grande City, Rio Grande do Sul (RS), Brazil, has the highest national rate of HIV/AIDS, considering cities with population more than 100,000 habitants. OBJECTIVE: We aimed to evaluate the clinical and epidemiological profile of cryptococcosis in a reference service for HIV-AIDS patients in the South region of Brazil, over seven years. Material and methods A retrospective study was performed including all cryptococcosis cases diagnosed at the University Hospital, Federal University of Rio Grande (UH-FURG) between January 2010 and December 2016. RESULTS: Seventy cases of cryptococcosis were diagnosis from 2010 to 2016 in the UH-FURG in the seven years of the study. These numbers were responsible for 2.1% to 8.1% of the hospitalizations/year for HIV patients. All were caused by C. neoformans infection (95% C. neoformans var. grubii VNI and 5% C. neoformans var. grubii VNII). Neurocryptococcosis was the major clinical manifestation and cryptococcosis was the HIV- defining condition in 40% of patients. The period of hospitalization was an average of 39.3 days (SD=31.3), and more than half of patients (53%; 37/70) died after a mean of 82 days. DISCUSSION: The present study showed the importance of cryptococcosis as an AIDS-defining disease in HIV-AIDS patients in a tertiary hospital from Southern Brazil. More investment is necessary to reduce the impact of this opportunistic mycosis in HIV-AIDS patients from southern Brazil.


Asunto(s)
Infecciones Oportunistas Relacionadas con el SIDA/epidemiología , Síndrome de Inmunodeficiencia Adquirida/epidemiología , Criptococosis/epidemiología , Infecciones por VIH/epidemiología , Infecciones Oportunistas Relacionadas con el SIDA/microbiología , Síndrome de Inmunodeficiencia Adquirida/complicaciones , Síndrome de Inmunodeficiencia Adquirida/microbiología , Adulto , Anciano , Brasil/epidemiología , Criptococosis/complicaciones , Criptococosis/microbiología , Cryptococcus neoformans/aislamiento & purificación , Femenino , VIH , Infecciones por VIH/complicaciones , Infecciones por VIH/microbiología , Hospitalización/estadística & datos numéricos , Humanos , Masculino , Meningitis Fúngica/epidemiología , Meningitis Fúngica/etiología , Meningitis Fúngica/microbiología , Persona de Mediana Edad , Prevalencia , Estudios Retrospectivos , Análisis de Supervivencia , Adulto Joven
4.
Neotrop Entomol ; 49(5): 722-738, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32720065

RESUMEN

We present surveys of derbid planthoppers associated with coconut (Cocos nucifera L.) and oil palm (Elaeis guineensis Jacq.) collected in Northeastern (Sergipe) and North (Pará and Roraima) Brazil. The surveys were intended to contribute to our knowledge of possible vectors of phytoplasmas or other phloem-restricted plant pathogens. Eight derbid taxa were found, two in the subfamily Cedusinae, tribe Cedusini (Cedusa yipara Kramer and C. yowza Kramer) and six in the subfamily Derbinae, tribe Cenchreini: Herpis sp., Persis pugnax Stål, Omolicna anastomosa (Caldwell), O. nigripennis (Caldwell), and two new species in the genus Agoo Bahder & Bartlett are described here. Genus-level features between Omolicna and Agoo are discussed and a key to the species of Agoo is provided.


Asunto(s)
Arecaceae , Cocos , Hemípteros/anatomía & histología , Hemípteros/clasificación , Animales , Brasil , Femenino , Insectos Vectores/anatomía & histología , Insectos Vectores/clasificación , Masculino , Phytoplasma
6.
J Chem Phys ; 151(8): 084310, 2019 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-31470731

RESUMEN

Measurements of the total electron scattering cross sections (TCSs) from benzene, in the impact energy range of 1-1000 eV, are presented here by combining two different experimental systems. The first utilizes a magnetically confined electron transmission beam for the lower energies (1-300 eV), while the second utilizes a linear transmission beam apparatus for the higher energies (100-1000 eV). These cross sections have also been calculated by means of two different theoretical methods, the Schwinger Multichannel with Pseudo Potential (SMCPP) procedure, employing two different approaches to account for the polarization of the target for impact energies between 0.1 and 15 eV, and the Independent Atom Model with the Screening Corrected Additivity Rule including Interference effect (IAM-SCAR+I) paradigm to cover the 10-10 000 eV impact energy range. The present results are compared with available theoretical and experimental data, with the level of accord being good in some cases and less satisfactory in others, and some predicted resonances have been identified. In particular, we found a π* shape resonance at 1.4 eV and another feature in the energy region 4.6-4.9 eV interpreted as a π* resonance (2B2g symmetry), which is a mixture of shape and a core excited resonance, as well as a Feshbach resonance at 5.87 eV associated with the 3s (a1g) Rydberg state. A Born-type formula to extrapolate TCS values for energies above 10 000 eV is also given. This study provides a complete set of TCS data, with uncertainty limits within 10%, ready to be used for modeling electron transport applications.

7.
J Helminthol ; 94: e50, 2019 Apr 11.
Artículo en Inglés | MEDLINE | ID: mdl-30973122

RESUMEN

New therapeutic approaches are necessary to control strongyloidiasis due to the side effects of, and resistance to, currently available drugs thiabendazole, albendazole, and ivermectin. This study examined the anthelmintic properties of extracts and isolated compounds from Siparuna guianensis against Strongyloides venezuelensis eggs and larvae, using the egg hatching test (EHT) and larval motility test (LMT). Albendazole (0.025 mg/ml) and ivermectin (0.316 mg/ml) were used as the positive controls for the EHT and LMT assays, respectively. Strongyloides venezuelensis eggs or larvae (±50 specimens) were treated with ethanol extract (0.05-1.0 mg/ml), ethyl acetate and aqueous fractions (0.05-0.8 mg/ml), essential oil (0.2-1.0 mg/ml) and α-bisabolol (0.2-1.0 mg/ml) from S. guianensis, and analysed by optical microscopy after 48 h (EHT), or after 24, 48 and 72 h (LMT). All the tested compounds exhibited ovicidal activity equivalent to the positive control and changed the morphology of the eggs. The S. guianensis ethanol extract and aqueous fraction were as effective as the positive control. Phytochemical analysis of the ethanol extract and fractions revealed the presence of phenolic compounds, tannins and flavonoids. Therefore, S. guianensis is effective against S. venezuelensis eggs and larvae in vitro, and can be considered as a potential alternative treatment for strongyloidiasis.


Asunto(s)
Antihelmínticos/farmacología , Aceites Volátiles/farmacología , Extractos Vegetales/farmacología , Strongyloides/efectos de los fármacos , Tracheophyta/química , Animales , Antihelmínticos/química , Larva/efectos de los fármacos , Sesquiterpenos Monocíclicos/química , Sesquiterpenos Monocíclicos/farmacología , Aceites Volátiles/química , Óvulo/efectos de los fármacos , Extractos Vegetales/química
8.
Braz J Med Biol Res ; 51(11): e7356, 2018 Oct 04.
Artículo en Inglés | MEDLINE | ID: mdl-30304130

RESUMEN

Essential oils (EO) are volatile liquids responsible for the aroma of plants. Pterodon polygalaeflorus seeds have received widespread use in folk medicine for the treatment of inflammatory diseases. For this reason and because Pterodon polygalaeflorus seeds have great EO content, which is frequently pharmacologically active, the present study aimed to evaluate the antinociceptive effect of EO from Pterodon polygalaeflorus (EOPPgfl) and its acute toxic effects. The EEOPPgfl sample, which was extracted by steam distillation of the seeds, had a yield of 2.4% of the seeds weight and had, as major constituents, beta-elemene (48.19%), trans-caryophyllene (19.51%), and epi-bicyclosesquiphellandrene (12.24%). The EOPPgfl sample showed mild acute toxicity and its calculated median lethal dose (LD50) was 3.38 g/kg. EOPPgfl (20-60 mg/kg) showed antinociceptive activity as evidenced by several tests and inhibited writhing induced by acetic acid. The maximum effect was obtained with the 30 mg/kg dose and at 60 min after its administration. EOPPgfl also decreased formalin-induced nociception, as verified by the inhibition of the first and second phase of the formalin test. At 30 mg/kg, EOPPgfl also decreased thermally stimulated nociception. Nociception may be related to inflammatory and antiedematogenic activity and at doses ranging 10-100 mg/kg, EOPPgfl blocked dextran- and carrageenan-induced edema. The results demonstrated that EOPPgfl presented, at doses approximately 100 times smaller than LD50, an antinociceptive effect that probably was due to anti-inflammatory activities.


Asunto(s)
Analgésicos/farmacología , Fabaceae/química , Nocicepción/efectos de los fármacos , Aceites Volátiles/farmacología , Extractos Vegetales/farmacología , Aceites de Plantas/farmacología , Animales , Antiinflamatorios/farmacología , Ratones , Dimensión del Dolor , Distribución Aleatoria , Reproducibilidad de los Resultados , Semillas/química , Factores de Tiempo , Resultado del Tratamiento
9.
Transbound Emerg Dis ; 65(5): 1381-1395, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-29603890

RESUMEN

Papillomaviruses (PVs) are complex viruses which infect the skin or mucosae of a broad range of amniotes worldwide. They cause benign or malignant lesions depending on environmental factors, virus oncogenicity and the location of infection. Bovine papillomaviruses (BPVs) are the second most studied PVs beyond human PVs. In the past few years, genetic characterization of animal PVs has increased due to the availability of new techniques, which simplified the sequencing of entire genomes. Therefore, this review aims to provide an update of the current epidemiology, classification and genome features of ruminant PVs (mainly BPVs) affecting animals worldwide. The review also aimed to clarify the key differences between the high-risk Delta papillomaviruses and the seemingly low-risk Xi, Epsilon, Dyoxi and Dyokappapillomavirus as well as the recently described PVs BPV18, 19, 21 and PpuPV1 that belongs to an unclassified genus.


Asunto(s)
Enfermedades de los Bovinos/virología , Papillomaviridae , Infecciones por Papillomavirus/virología , Rumiantes/virología , Animales , Bovinos , Enfermedades de los Bovinos/epidemiología , Humanos , Papillomaviridae/clasificación , Papillomaviridae/genética , Infecciones por Papillomavirus/clasificación , Infecciones por Papillomavirus/epidemiología , Infecciones por Papillomavirus/genética , Filogenia , Estructuras Virales/fisiología
10.
Braz. j. med. biol. res ; 51(11): e7356, 2018. tab, graf
Artículo en Inglés | LILACS | ID: biblio-951728

RESUMEN

Essential oils (EO) are volatile liquids responsible for the aroma of plants. Pterodon polygalaeflorus seeds have received widespread use in folk medicine for the treatment of inflammatory diseases. For this reason and because Pterodon polygalaeflorus seeds have great EO content, which is frequently pharmacologically active, the present study aimed to evaluate the antinociceptive effect of EO from Pterodon polygalaeflorus (EOPPgfl) and its acute toxic effects. The EEOPPgfl sample, which was extracted by steam distillation of the seeds, had a yield of 2.4% of the seeds weight and had, as major constituents, beta-elemene (48.19%), trans-caryophyllene (19.51%), and epi-bicyclosesquiphellandrene (12.24%). The EOPPgfl sample showed mild acute toxicity and its calculated median lethal dose (LD50) was 3.38 g/kg. EOPPgfl (20-60 mg/kg) showed antinociceptive activity as evidenced by several tests and inhibited writhing induced by acetic acid. The maximum effect was obtained with the 30 mg/kg dose and at 60 min after its administration. EOPPgfl also decreased formalin-induced nociception, as verified by the inhibition of the first and second phase of the formalin test. At 30 mg/kg, EOPPgfl also decreased thermally stimulated nociception. Nociception may be related to inflammatory and antiedematogenic activity and at doses ranging 10-100 mg/kg, EOPPgfl blocked dextran- and carrageenan-induced edema. The results demonstrated that EOPPgfl presented, at doses approximately 100 times smaller than LD50, an antinociceptive effect that probably was due to anti-inflammatory activities.


Asunto(s)
Animales , Conejos , Aceites de Plantas/farmacología , Aceites Volátiles/farmacología , Extractos Vegetales/farmacología , Nocicepción/efectos de los fármacos , Analgésicos/farmacología , Fabaceae/química , Semillas/química , Factores de Tiempo , Dimensión del Dolor , Distribución Aleatoria , Reproducibilidad de los Resultados , Resultado del Tratamiento , Antiinflamatorios/farmacología
11.
Braz J Med Biol Res ; 50(12): e6351, 2017 Oct 19.
Artículo en Inglés | MEDLINE | ID: mdl-29069226

RESUMEN

Lippia sidoides Cham is a typical herb species of Northeast Brazil with widespread use in folk medicine. The major constituents of the essential oil of L. sidoides (EOLs) are thymol, p-cymene, myrcene, and caryophyllene. Several studies have shown that the EOLs and its constituents have pharmacological effects, including antibacterial, anti-inflammatory, antioxidant and neuroprotective activity. Therefore, this work aimed to investigate the effects of the EOLs and their main constituents on rat sciatic nerve excitability. The sciatic nerves of adult Wistar rats were dissected and mounted in a moist chamber. Nerves were stimulated by square wave pulses, with an amplitude of 40 V, duration of 100 µs to 0.2 Hz. Both EOLs and thymol inhibited compound action potential (CAP) in a concentration-dependent manner. Half maximal inhibitory concentration for CAP peak-to-peak amplitude blockade were 67.85 and 40 µg/mL for EOLs and thymol, respectively. CAP peak-to-peak amplitude was significantly reduced by concentrations ≥60 µg/mL for EOLs and ≥30 µg/mL for thymol. EOLs and thymol in the concentration of 60 µg/mL significantly increased chronaxie and rheobase. The conduction velocities of 1st and 2nd CAP components were also concentration-dependently reduced by EOLs and thymol in the range of 30-100 µg/mL. Differently from EOLs and thymol, p-cymene, myrcene and caryophyllene did not reduce CAP in the higher concentrations of 10 mM. These data demonstrated that EOLs and thymol inhibited neuronal excitability and were promising agents for the development of new drugs for therapeutic use.


Asunto(s)
Alquenos/farmacología , Lippia/química , Monoterpenos/farmacología , Aceites Volátiles/farmacología , Nervio Ciático/efectos de los fármacos , Sesquiterpenos/farmacología , Timol/farmacología , Potenciales de Acción/efectos de los fármacos , Potenciales de Acción/fisiología , Monoterpenos Acíclicos , Animales , Cimenos , Femenino , Masculino , Bloqueo Nervioso/métodos , Conducción Nerviosa/efectos de los fármacos , Aceites Volátiles/química , Sesquiterpenos Policíclicos , Ratas Wistar , Reproducibilidad de los Resultados , Nervio Ciático/fisiología , Factores de Tiempo
12.
J Periodontal Res ; 52(5): 883-892, 2017 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-28504459

RESUMEN

BACKGROUND AND OBJECTIVE: Periodontitis may promote harmful systemic effects such as changes in hepatic tissues. The purpose of this study was to investigate whether the steatosis and oxidative stress caused by experimental periodontitis are reversible in the liver. MATERIAL AND METHODS: Twenty-four rats were divided into three groups: control, periodontitis and P20-20 (20 days with experimental periodontitis and 20 days without experimental periodontitis, to verify the reversibility of hepatic injuries). The following parameters were assessed: gingival bleeding index, probing pocket depth, myeloperoxidase activity, alveolar bone loss for periodontal tissues; liver weights, histopathological scores for steatosis, inflammation and necrosis in liver; glutathione, malondialdehyde, total cholesterol and triglyceride concentrations in hepatic tissues; and blood levels of aspartate aminotransferase, alanine aminotransferase, albumin, gamma-glutaryl transferase, total cholesterol and random glucose. RESULTS: Gingival bleeding index, probing pocket depth, myeloperoxidase and alveolar bone loss parameters demonstrated the development of periodontitis. There was a significant reduction in the steatosis score of animals from the P20-20 group when compared with the periodontitis group. P20-20 group presented significantly higher glutathione (11 times) and lower malondialdehyde (nearly 23%), total cholesterol (both in blood and hepatic tissue) and triglyceride concentrations compared with the periodontitis group. For levels of aspartate aminotransferase, alanine aminotransferase, albumin, gamma-glutaryl transferase and random glucose, a significant difference between the groups was not observed. CONCLUSION: Our results demonstrate that the microvesicular steatosis caused by periodontitis in rats is reversible after removal of the ligature, which is associated with the increase in oxidative stress and lipid peroxidation in the liver.


Asunto(s)
Hígado Graso/etiología , Hígado Graso/terapia , Ligadura/métodos , Estrés Oxidativo , Periodontitis/complicaciones , Alanina Transaminasa/sangre , Pérdida de Hueso Alveolar/clasificación , Pérdida de Hueso Alveolar/patología , Animales , Aspartato Aminotransferasas/sangre , Glucemia , Colesterol/análisis , Colesterol/sangre , Modelos Animales de Enfermedad , Hígado Graso/patología , Femenino , Encía/patología , Glutatión/análisis , Inflamación , Peroxidación de Lípido , Hígado/lesiones , Hígado/patología , Malondialdehído/análisis , Necrosis/patología , Índice Periodontal , Bolsa Periodontal/patología , Periodontitis/patología , Peroxidasa/metabolismo , Ratas , Ratas Wistar , Albúmina Sérica , Factores de Tiempo , Transaminasas/sangre , Triglicéridos/análisis , gamma-Glutamiltransferasa/sangre
13.
Breast ; 31: 192-196, 2017 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-27889595

RESUMEN

INTRODUCTION: Locally advanced breast cancer (LABC) is a major problem, especially in developing countries. The standard treatment for LABC is neoadjuvant chemotherapy, with or without anti-Her2 therapy, followed by surgery, radiotherapy, and adjuvant systemic treatment if appropriate. However, there are few data in the literature addressing alternatives when neoadjuvant chemotherapy fails to reduce the tumour for surgery. MATERIALS AND METHODS: We conducted a retrospective study including all patients who had non-metastatic LABC treated with neoadjuvant chemotherapy and who were not eligible for surgical resection; these patients were submitted to salvage radiotherapy (RTX) between January 2000 and December 2012 at the Brazilian National Cancer Institute. RESULTS: Fifty-seven patients were included, with a median age of 51 (23-72) years. The most frequent clinical stages were IIIA and IIIB, corresponding to 19.3% and 70.2%, respectively; mean tumour size was 8.74 (3-18) cm, and 44 patients (77.2%) had nodal involvement. Chemotherapeutic regimens containing anthracyclines were prescribed to 98.2% of the patients. Fifteen patients (26.3%) received taxanes and anthracyclines. Radiation dose was 50 Gy divided into 25 fractions; 43 patients (75.4%) had their tumours downsized by RTX and underwent mastectomy. Overall survival (OS) was 38 (23-52) months. Patients who were submitted to surgery had an OS of 49 (28-70) months and those who were not eligible for mastectomy after radiotherapy had an OS of 18 (9-27) months. CONCLUSION: This retrospective study confirms that RTX is an effective treatment to downsize LABC tumours with low or no response to chemotherapy, thereby enabling surgical resection which may improve overall patient outcome.


Asunto(s)
Neoplasias de la Mama/patología , Neoplasias de la Mama/radioterapia , Carcinoma Ductal de Mama/radioterapia , Carcinoma Lobular/radioterapia , Terapia Recuperativa , Adulto , Anciano , Antraciclinas/administración & dosificación , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias de la Mama/terapia , Hidrocarburos Aromáticos con Puentes/administración & dosificación , Carcinoma Ductal de Mama/secundario , Carcinoma Ductal de Mama/terapia , Carcinoma Lobular/secundario , Carcinoma Lobular/terapia , Quimioterapia Adyuvante , Supervivencia sin Enfermedad , Fraccionamiento de la Dosis de Radiación , Femenino , Humanos , Mastectomía , Persona de Mediana Edad , Terapia Neoadyuvante , Estadificación de Neoplasias , Estudios Retrospectivos , Tasa de Supervivencia , Taxoides/administración & dosificación , Carga Tumoral , Adulto Joven
14.
J Phys Chem A ; 120(45): 8998-9007, 2016 Nov 17.
Artículo en Inglés | MEDLINE | ID: mdl-27766869

RESUMEN

Here we report novel comprehensive investigations on the electronic state spectroscopies of isolated 2,4- and 2,6-difluorotoluene in the gas phase by high-resolution vacuum ultraviolet (VUV) photoabsorption measurements in the 4.4-10.8 eV energy range, with absolute cross-section values derived. We also present the first set of ab initio calculations (vertical energies and oscillator strengths), which we have used in the assignment of valence transitions of the difluorotoluene molecules, together with calculated ionization energies to obtain the Rydberg transitions for both molecules. The measured absolute photoabsorption cross sections have been used to estimate the photolysis lifetimes of 2,4- and 2,6-difluorotoluene in the Earth's atmosphere.

15.
J Chem Phys ; 145(3): 034302, 2016 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-27448882

RESUMEN

We present the experimental high-resolution vacuum ultraviolet (VUV) photoabsorption spectra of phenol covering for the first time the full 4.3-10.8 eV energy-range, with absolute cross sections determined. Theoretical calculations on the vertical excitation energies and oscillator strengths were performed using time-dependent density functional theory and the equation-of-motion coupled cluster method restricted to single and double excitations level. These have been used in the assignment of valence and Rydberg transitions of the phenol molecule. The VUV spectrum reveals several new features not previously reported in the literature, with particular reference to the 6.401 eV transition, which is here assigned to the 3sσ/σ(∗)(OH)←3π(3a″) transition. The measured absolute photoabsorption cross sections have been used to calculate the photolysis lifetime of phenol in the earth's atmosphere (0-50 km).

17.
Braz. j. med. biol. res ; 48(10): 895-901, Oct. 2015. tab
Artículo en Inglés | LILACS | ID: lil-761598

RESUMEN

According to the International Atomic Energy Agency (IAEA), a relatively significant number of radiological accidents have occurred in recent years mainly because of the practices referred to as potentially high-risk activities, such as radiotherapy, large irradiators and industrial radiography, especially in gammagraphy assays. In some instances, severe injuries have occurred in exposed persons due to high radiation doses. In industrial radiography, 80 cases involving a total of 120 radiation workers, 110 members of the public including 12 deaths have been recorded up to 2014. Radiological accidents in industrial practices in Brazil have mainly resulted in development of cutaneous radiation syndrome (CRS) in hands and fingers. Brazilian data include 5 serious cases related to industrial gammagraphy, affecting 7 radiation workers and 19 members of the public; however, none of them were fatal. Some methods of reconstructive dosimetry have been used to estimate the radiation dose to assist in prescribing medical treatment. The type and development of cutaneous manifestations in the exposed areas of a person is the first achievable gross dose estimation. This review article presents the state-of-the-art reconstructive dosimetry methods enabling estimation of local radiation doses and provides guidelines for medical handling of the exposed individuals. The review also presents the Chilean and Brazilian radiological accident cases to highlight the importance of reconstructive dosimetry.


Asunto(s)
Humanos , Traumatismos por Radiación/diagnóstico , Liberación de Radiactividad Peligrosa/estadística & datos numéricos , Radiometría/métodos , Piel/efectos de la radiación , Brasil/epidemiología , Chile/epidemiología , Espectroscopía de Resonancia por Spin del Electrón , Traumatismos de los Dedos/etiología , Traumatismos de la Mano/etiología , Mediciones Luminiscentes , Dosis de Radiación , Exposición a la Radiación/efectos adversos , Traumatismos por Radiación/epidemiología
18.
EPJ Tech Instrum ; 2(1): 13, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26322266

RESUMEN

We report a novel experimental setup for studying collision induced products resulting from the interaction of anionic beams with a neutral gas-phase molecular target. The precursor projectile was admitted into vacuum through a commercial pulsed valve, with the anionic beam produced in a hollow cathode discharge-induced plasma, and guided to the interaction region by a set of deflecting plates where it was made to interact with the target beam. Depending on the collision energy regime, negative and positive species can be formed in the collision region and ions were time-of-flight (TOF) mass-analysed. Here, we present data on O2 precursor projectile, where we show clear evidence of O- and O2- formation from the hollow cathode source as well as preliminary results on the interaction of these anions with nitromethane, CH3NO2. The negative ions formed in such collisions were analysed using time-of-flight mass spectrometry. The five most dominant product anions were assigned to H-, O-, NO-, CNO- and CH3NO2-.

19.
J Phys Chem A ; 119(34): 9059-69, 2015 Aug 27.
Artículo en Inglés | MEDLINE | ID: mdl-26244250

RESUMEN

The electronic spectroscopy of isolated toluene in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 4.0-10.8 eV energy range, with absolute cross-section measurements derived. We present the first set of ab initio calculations (vertical energies and oscillator strengths), which we use in the assignment of valence and Rydberg transitions of the toluene molecule. The spectrum reveals several new features not previously reported in the literature, with particular relevance to 7.989 and 8.958 eV, which are here tentatively assigned to the π*(17a') ← σ(15a') and 1π*(10a″) ← 1π(14a') transitions, respectively. The measured absolute photoabsorption cross sections have been used to calculate the photolysis lifetime of toluene in the upper stratosphere (20-50 km).


Asunto(s)
Electrones , Teoría Cuántica , Sincrotrones , Tolueno/química , Rayos Ultravioleta , Absorción de Radiación , Atmósfera , Fotólisis , Espectrofotometría Ultravioleta , Vacio
20.
J Phys Chem A ; 119(31): 8503-11, 2015 Aug 06.
Artículo en Inglés | MEDLINE | ID: mdl-26171941

RESUMEN

We present the first set of ab initio calculations (vertical energies and oscillator strengths) of the valence and Rydberg transitions of the anaesthetic compound halothane (CF3CHBrCl). These results are complemented by high-resolution vacuum ultraviolet photoabsorption measurements over the wavelength range 115-310 nm (10.8-4.0 eV). The spectrum reveals several new features that were not previously reported in the literature. Spin-orbit effects have been considered in the calculations for the lowest-lying states, allowing us to explain the broad nature of the 6.1 and 7.5 eV absorption bands assigned to σ*(C-Br) ← nBr and σ*(C-Cl) ← n(Cl) transitions. Novel absolute photoabsorption cross sections from electron scattering data were derived in the 4.0-40.0 eV range. The measured absolute photoabsorption cross sections have been used to calculate the photolysis lifetime of halothane in the upper stratosphere (20-50 km).


Asunto(s)
Electrones , Halotano/química , Teoría Cuántica , Rayos Ultravioleta , Espectroscopía de Fotoelectrones , Sincrotrones , Vacio
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