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Showing 401 - 600 of 729 Journals sorted alphabetically
Psicología desde el Caribe     Open Access  
Psicologia em Estudo     Open Access   (SJR: 0.208, h-index: 8)
Psicologia Escolar e Educacional     Open Access   (SJR: 0.101, h-index: 1)
Psicologia USP     Open Access   (SJR: 0.178, h-index: 4)
Psychology & Neuroscience     Open Access   (Followers: 13, SJR: 0.261, h-index: 5)
Psychology in Society     Open Access   (Followers: 2)
Psykhe (Santiago)     Open Access   (SJR: 0.29, h-index: 6)
Química Nova     Open Access   (SJR: 0.293, h-index: 41)
Radiologia Brasileira     Open Access   (Followers: 1, SJR: 0.201, h-index: 7)
RAE-eletrônica     Open Access  
RAM. Revista de Administração Mackenzie     Open Access  
RCOE     Open Access  
REAd : Revista eletrônica de administração     Open Access  
Región y Sociedad     Open Access  
Relações Internacionais (R:I)     Open Access  
Religião e Sociedade     Open Access   (Followers: 3)
Rem : Revista Escola de Minas     Open Access   (Followers: 1, SJR: 0.232, h-index: 6)
Revista Americana de Medicina Respiratoria     Open Access  
Revista Andaluza de Medicina del Deporte     Open Access   (Followers: 2, SJR: 0.148, h-index: 4)
Revista Archivo Médico de Camagüey     Open Access  
Revista Árvore     Open Access   (Followers: 1, SJR: 0.486, h-index: 15)
Revista Brasileira de Biologia     Open Access  
Revista Brasileira de Cardiologia Invasiva     Open Access   (SJR: 0.116, h-index: 5)
Revista Brasileira de Ciência Avicola     Open Access   (Followers: 1, SJR: 0.266, h-index: 9)
Revista Brasileira de Ciência do Solo     Open Access   (Followers: 1, SJR: 1.001, h-index: 29)
Revista Brasileira de Ciência Política     Open Access  
Revista Brasileira de Ciências do Esporte     Open Access   (Followers: 1)
Revista Brasileira de Ciências Farmaceuticas     Open Access  
Revista Brasileira de Ciências Sociais     Open Access   (Followers: 1, SJR: 0.163, h-index: 5)
Revista Brasileira de Cineantropometria & Desempenho Humano     Open Access   (SJR: 0.255, h-index: 10)
Revista Brasileira de Cirurgia Cardiovascular     Open Access   (SJR: 0.302, h-index: 13)
Revista Brasileira de Cirurgia Plástica     Open Access   (Followers: 1)
Revista Brasileira de Coloproctologia     Open Access  
Revista Brasileira de Economia     Open Access   (Followers: 1, SJR: 0.277, h-index: 6)
Revista Brasileira de Educação     Open Access   (SJR: 0.274, h-index: 4)
Revista Brasileira de Educação Especial     Open Access   (SJR: 0.201, h-index: 5)
Revista Brasileira de Educação Física e Esporte     Open Access   (Followers: 1)
Revista Brasileira de Educação Medica     Open Access  
Revista Brasileira de Enfermagem     Open Access   (SJR: 0.273, h-index: 10)
Revista Brasileira de Engenharia Agrícola e Ambiental     Open Access   (Followers: 1, SJR: 0.622, h-index: 17)
Revista Brasileira de Engenharia Biomédica     Open Access   (SJR: 0.147, h-index: 2)
Revista Brasileira de Ensino de Fisica     Open Access   (SJR: 0.201, h-index: 4)
Revista Brasileira de Entomologia     Open Access   (Followers: 1, SJR: 0.446, h-index: 13)
Revista Brasileira de Epidemiologia     Open Access   (Followers: 2, SJR: 0.576, h-index: 14)
Revista Brasileira de Estudos de População     Open Access   (Followers: 1, SJR: 0.227, h-index: 5)
Revista Brasileira de Estudos Pedagógicos     Open Access  
Revista Brasileira de Farmacognosia     Open Access   (SJR: 0.371, h-index: 21)
Revista Brasileira de Fisiologia Vegetal     Open Access  
Revista Brasileira de Fruticultura     Open Access   (SJR: 0.468, h-index: 13)
Revista Brasileira de Geofísica     Open Access   (Followers: 2, SJR: 0.192, h-index: 10)
Revista Brasileira de Geriatria e Gerontologia     Open Access  
Revista Brasileira de Hematologia e Hemoterapia     Open Access   (Followers: 1, SJR: 0.148, h-index: 8)
Revista Brasileira de Historia     Open Access   (Followers: 3, SJR: 0.11, h-index: 4)
Revista Brasileira de Linguística Aplicada     Open Access  
Revista Brasileira de Medicina do Esporte     Open Access   (Followers: 1, SJR: 0.176, h-index: 14)
Revista Brasileira de Meteorologia     Open Access   (Followers: 1)
Revista Brasileira de Oftalmologia     Open Access   (SJR: 0.15, h-index: 7)
Revista Brasileira de Otorrinolaringologia     Open Access  
Revista Brasileira de Parasitologia Veterinaria     Open Access   (SJR: 0.419, h-index: 13)
Revista Brasileira de Plantas Medicinais     Open Access   (SJR: 0.226, h-index: 14)
Revista Brasileira de Política Internacional     Open Access   (SJR: 0.261, h-index: 5)
Revista Brasileira de Psiquiatria     Open Access   (Followers: 1, SJR: 0.477, h-index: 30)
Revista Brasileira de Reumatologia     Open Access   (SJR: 0.281, h-index: 13)
Revista Brasileira de Saúde e Produção Animal     Open Access   (SJR: 0.152, h-index: 2)
Revista Brasileira de Saúde Materno Infantil     Open Access   (SJR: 0.344, h-index: 13)
Revista Brasileira de Sementes     Open Access   (SJR: 0.336, h-index: 13)
Revista Brasileira de Terapia Intensiva     Open Access   (Followers: 1)
Revista Brasileira de Zoologia     Open Access  
Revista Brasileira de Zootecnia     Open Access   (Followers: 2, SJR: 0.37, h-index: 32)
Revista CEFAC     Open Access  
Revista Ceres     Open Access   (SJR: 0.202, h-index: 2)
Revista Chapingo. Serie horticultura     Open Access   (SJR: 0.125, h-index: 4)
Revista Chilena de Anatomia     Open Access  
Revista Chilena de Cardiología     Open Access  
Revista Chilena de Cirugia     Open Access   (SJR: 0.138, h-index: 5)
Revista Chilena de Derecho     Open Access   (SJR: 1.078, h-index: 3)
Revista Chilena de Derecho Privado     Open Access  
Revista Chilena de Enfermedades Respiratorias     Open Access   (SJR: 0.139, h-index: 6)
Revista Chilena de Infectología     Open Access   (SJR: 0.173, h-index: 12)
Revista Chilena de Literatura     Open Access   (Followers: 2, SJR: 0.123, h-index: 3)
Revista Chilena de Neuro-Psiquiatria     Open Access   (SJR: 0.119, h-index: 8)
Revista Chilena de Nutricion     Open Access   (Followers: 1, SJR: 0.204, h-index: 6)
Revista Chilena de Obstetricia y Ginecologia     Open Access   (Followers: 1, SJR: 0.156, h-index: 7)
Revista Chilena de Pediatria     Open Access   (SJR: 0.132, h-index: 9)
Revista Chilena de Radiologia     Open Access   (Followers: 1, SJR: 0.1, h-index: 3)
Revista Ciência Agronômica     Open Access   (SJR: 0.782, h-index: 10)
Revista Ciencias Técnicas Agropecuarias     Open Access  
Revista Científica Ciencia Médica     Open Access  
Revista Científica General José María Córdova     Open Access  
Revista Clínica de Medicina de Familia     Open Access   (Followers: 4)
Revista Clínica de Periodoncia, Implantología y Rehabilitación Oral     Open Access   (Followers: 1)
Revista Colombiana de Anestesiología     Open Access   (Followers: 2, SJR: 0.13, h-index: 3)
Revista Colombiana de Biotecnología     Open Access   (Followers: 1)
Revista Colombiana de Cirugía     Open Access  
Revista Colombiana de Educación     Open Access  
Revista Colombiana de Entomología     Open Access   (Followers: 2, SJR: 0.241, h-index: 8)
Revista Colombiana de Estadística     Open Access   (SJR: 0.274, h-index: 4)
Revista Colombiana de Matemáticas     Open Access   (Followers: 1)
Revista Colombiana de Psicología     Open Access   (SJR: 0.112, h-index: 2)
Revista Contabilidade & Finanças     Open Access  
Revista Costarricense de Cardiología     Open Access  
Revista Costarricense de Psicología     Open Access  
Revista Cubana de Anestesiología y Reanimación     Open Access   (Followers: 1)
Revista Cubana de Angiología y Cirugía Vascular     Open Access  
Revista Cubana de Cirugía     Open Access   (SJR: 0.119, h-index: 4)
Revista Cubana de Endocrinología     Open Access  
Revista Cubana de Enfermería     Open Access   (Followers: 2, SJR: 0.138, h-index: 4)
Revista Cubana de Estomatologí­a     Open Access  
Revista Cubana de Farmacia     Open Access   (Followers: 1, SJR: 0.146, h-index: 4)
Revista Cubana de Hematología, Inmunología y Hemoterapia     Open Access   (SJR: 0.119, h-index: 5)
Revista Cubana de Higiene y Epidemiología     Open Access   (SJR: 0.14, h-index: 6)
Revista Cubana de Información en Ciencias de la Salud     Open Access  
Revista Cubana de Informática Médica     Open Access  
Revista Cubana de Investigaciones Biomédicas     Open Access   (Followers: 1)
Revista Cubana de Medicina     Open Access   (Followers: 2, SJR: 0.108, h-index: 6)
Revista Cubana de Medicina General Integral     Open Access   (Followers: 1, SJR: 0.1, h-index: 9)
Revista Cubana de Medicina Militar     Open Access   (Followers: 1, SJR: 0.1, h-index: 6)
Revista Cubana de Medicina Tropical     Open Access   (SJR: 0.136, h-index: 12)
Revista Cubana de Obstetricia y Ginecología     Open Access   (SJR: 0.152, h-index: 7)
Revista Cubana de Oftalmología     Open Access   (Followers: 1)
Revista Cubana de Ortopedia y Traumatología     Open Access   (SJR: 0.1, h-index: 4)
Revista Cubana de Pediatrí­a     Open Access  
Revista Cubana de Plantas Medicinales     Open Access   (Followers: 1, SJR: 0.16, h-index: 7)
Revista Cubana de Salud Pública     Open Access   (SJR: 0.168, h-index: 6)
Revista da Educação Física : UEM     Open Access   (SJR: 0.113, h-index: 2)
Revista da Escola de Enfermagem da USP     Open Access   (Followers: 2, SJR: 0.412, h-index: 16)
Revista da Faculdade de Educação     Open Access  
Revista da Sociedade Brasileira de Fonoaudiologia     Open Access  
Revista da Sociedade Brasileira de Medicina Tropical     Open Access   (SJR: 0.497, h-index: 35)
Revista de Administração Contemporânea     Open Access  
Revista de Administração de Empresas     Open Access   (Followers: 1, SJR: 0.208, h-index: 4)
Revista de Administração Pública     Open Access   (SJR: 0.203, h-index: 6)
Revista de Análisis Económico     Open Access   (SJR: 0.127, h-index: 1)
Revista de Antropologia     Open Access   (Followers: 3, SJR: 0.101, h-index: 3)
Revista de Bioética y Derecho     Open Access  
Revista de Biología Marina y Oceanografía     Open Access   (SJR: 0.279, h-index: 14)
Revista de Biología Tropical     Open Access   (Followers: 2, SJR: 0.327, h-index: 23)
Revista de Ciencia Politica     Open Access   (Followers: 2, SJR: 0.307, h-index: 7)
Revista de Ciencia y Tecnología     Open Access  
Revista de Ciências Agrárias     Open Access  
Revista de Ciencias Médicas de Pinar del Río     Open Access  
Revista de Ciencias Sociales     Open Access  
Revista de Derecho     Open Access   (Followers: 1, SJR: 0.418, h-index: 3)
Revista de Derecho (Coquimbo)     Open Access  
Revista de Economia Contemporânea     Open Access   (SJR: 0.186, h-index: 3)
Revista de Economía del Caribe     Open Access  
Revista de Economia e Sociologia Rural     Open Access   (Followers: 2, SJR: 0.213, h-index: 5)
Revista de Economía Institucional     Open Access   (SJR: 0.139, h-index: 2)
Revista de Economia Poli­tíca     Open Access   (Followers: 1, SJR: 0.224, h-index: 6)
Revista de Enfermagem Referência     Open Access   (Followers: 2)
Revista de Estudios Historico-Juridicos     Open Access   (Followers: 1, SJR: 0.1, h-index: 2)
Revista de Estudios Sociales     Open Access   (Followers: 1)
Revista de Filosofia     Open Access   (SJR: 0.11, h-index: 1)
Revista de Geografía Norte Grande     Open Access   (SJR: 0.148, h-index: 5)
Revista de Gestão Costeira Integrada     Open Access  
Revista de Historia Americana y Argentina     Open Access  
Revista de Ingeniería     Open Access  
Revista de la Asociación Española de Neuropsiquiatría     Open Access  
Revista de la Ciencia del Suelo y Nutricion Vegetal     Open Access   (SJR: 0.282, h-index: 6)
Revista de la Construcción     Open Access   (SJR: 0.112, h-index: 3)
Revista de la Facultad de Derecho y Ciencias Políticas     Open Access  
Revista de la Sociedad Boliviana de Pediatría     Open Access  
Revista de la Sociedad Española de Enfermería Nefrológica     Open Access   (SJR: 0.169, h-index: 2)
Revista de la Universidad Industrial de Santander. Salud     Open Access  
Revista de Medicina Veterinaria     Open Access  
Revista de Microbiologia     Open Access   (Followers: 1)
Revista de Nefrología, Diálisis y Trasplante     Open Access   (Followers: 1)
Revista de Nutrição     Open Access   (SJR: 0.306, h-index: 22)
Revista de Odontologia da UNESP     Open Access  
Revista de Odontologia da Universidade de São Paulo     Open Access  
Revista de Osteoporosis y Metabolismo Mineral     Open Access   (Followers: 1)
Revista de Otorrinolaringología y Cirugía de Cabeza y Cuello     Open Access  
Revista de Protección Vegetal     Open Access  
Revista de Psicología del Trabajo y de las Organizaciones     Open Access   (SJR: 0.137, h-index: 2)
Revista de Psiquiatria Clínica     Open Access   (Followers: 1, SJR: 0.305, h-index: 14)
Revista de Psiquiatria do Rio Grande do Sul     Open Access   (Followers: 1, SJR: 0.215, h-index: 9)
Revista de Salud Animal     Open Access  
Revista de Salud Pública     Open Access   (Followers: 1, SJR: 0.249, h-index: 12)
Revista de Saúde Pública     Open Access   (Followers: 1, SJR: 0.807, h-index: 48)
Revista de Sociologia e Polí­tica     Open Access   (Followers: 2, SJR: 0.178, h-index: 4)
Revista Dental Press de Ortodontia e Ortopedia Facial     Open Access   (Followers: 1)
Revista Diacrítica     Open Access  
Revista Direito GV     Open Access   (Followers: 1)
Revista do Colégio Brasileiro de Cirurgiões     Open Access   (SJR: 0.209, h-index: 7)
Revista do Departamento de Psicologia. UFF     Open Access  
Revista do Hospital das Clinicas     Open Access  
Revista do Instituto de Estudos Brasileiros     Open Access  
Revista do Instituto de Medicina Tropical de São Paulo     Open Access   (SJR: 0.451, h-index: 33)
Revista Dor     Open Access  
Revista EIA     Open Access   (Followers: 1)
Revista electrónica de investigación educativa     Open Access   (Followers: 1, SJR: 0.1, h-index: 2)
Revista Española de Cirugía Oral y Maxilofacial     Open Access   (Followers: 1, SJR: 0.123, h-index: 3)
Revista Española de Enfermedades Digestivas     Open Access   (Followers: 1, SJR: 0.294, h-index: 24)
Revista Española de Salud Pública     Open Access   (SJR: 0.216, h-index: 21)
Revista Española de Sanidad Penitenciaria     Open Access   (SJR: 0.122, h-index: 1)
Revista Estudos Feministas     Open Access   (SJR: 0.233, h-index: 6)
Revista Facultad de Ciencias Económicas: Investigación y Reflexión     Open Access  
Revista Facultad de Ingenieria - Universidad de Tarapaca     Open Access  
Revista Facultad de Ingeniería Universidad de Antioquia     Open Access   (Followers: 1, SJR: 0.139, h-index: 4)
Revista Facultad de Odontología Universidad de Antioquia     Open Access  

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Journal Cover Journal of the Chilean Chemical Society
  [SJR: 0.217]   [H-I: 18]   [2 followers]  Follow
    
  This is an Open Access Journal Open Access journal
   ISSN (Online) 0717-9324
   Published by SciELO Homepage  [729 journals]
  • ABSOLUTE CONFIGURATION ASSIGNMENT IN RACEMIC
           
    trans -STILBENE OXIDE USING CHIRAL
           LIQUID CHROMATOGRAPHY WITH COMBINED CHIROPTICAL DETECTION AND
           TIME-DEPENDENT DENSITY FUNCTIONAL THEORY CALCULATIONS

    • Abstract: A chiral chromatographic analysis using HPLC coupled in series with circular dichroism and optical rotation detectors (HPLC-CD-OR) was applied to racemic trans-stilbene oxide, allowing the on-line measurement of the CD spectra and [α] values for both enantiomers in the sample. These measurementsused the Gaussian peak model to estimate the concentration of each isomer in the CD and OR cells. Moreover, time-dependent density functional theory (TD-DFT) calculations at the B3LYP/TZVP//B3LYP/VDZ(P) and B3LYP/aug-cc-pVDZ//B3LYP/VDZ(P) levels of the ory for CD and OR, respectively, permitted the prediction of both chiroptical properties for each isomer, which in turn could be compared with the corresponding experimental data. In this case, the calculationswere consistent in predicting the correct combination of experimental CD bands and [a] sign and the refore facilitated the absolute configuration (AC) assignment of the optical isomers. The AC proposed using this methodology was in agreement with independent AC assignments in the literature.
       
  • LIQUID CHROMATOGRAPHIC DETERMINATION OF SOLIFENACIN SUCCINATE,
           FLAVOXATE HYDROCHLORIDE AND TOLTERODINE TARTRATE IN BULK DRUGS AND THEIR
           PHARMACEUTICAL DOSAGE FORMS

    • Abstract: A simple, precise, specific and accurate reversed phase HPLC (RP-HPLC) method has been developed for the determination of solifenacin succinate (SOLS), flavoxate HC1 (FLXHC) and toltoridine tartarate (TOLT) in bulk and pharmaceutical dosage forms. The proposed RP-HPLC method was carried out using XterraRP-18 column (5 μm practical size, 25 cm x 4.6 mm i.d.). The flow rate, the injection volume and the detection wavelength were 1.0 μL/min, 20 μL and 200 nm, respectively. The mobile phase consisted of 0.05 M pentane sulfonic acid sodium salt (SOLS: pH 3.0±0.05, FLXHC and TOLT: pH 5.5±0.05) and acetonitrile (50:50 v/v). The retention times for SOLS, FLXHC and TOLT drugs were found to be 4.1±0.1 min, 4.3±0.0 min and 5.8±0.1 min, respectively. The calibration was linear over the concentration range of 0.1-100 μg/μL. The mean recoveries for SOLS, FLXHC and TOLT drugs were about 99.80%, 100.43% and 100.00%, respectively. The method was validated according to the ICH guidelines with respect to specificity, linearity, accuracy, precision and robustness.
       
  • PREPARATION OF BORIC ACID MODIFIED EXPANDABLE GRAPHITE AND ITS
           INFLUENCE ON POLYETHYLENE COMBUSTION CHARACTERISTICS

    • Abstract: A boric acid modified expandable graphite (EG B) was prepared through oxidizing-intercalating reaction of natural graphite, using H2SO4 and boric acid (H3BO3) as intercalators simultaneously. The dilatability of the intercalated products were characterized with expansion volume and initial expansion temperature.Scanning electron microscope, X-ray diffraction spectroscopy, energy dispersive spectroscopy and Fourier transform infrared spectroscopy were employed todetect its layer structure, main element relative contents and function group. At the same time, its influence on combustion characteristics and thermal stability forlinear low density polyethylene (LLDPE) were investigated in limiting oxygen index (LOI) tests, vertical burning tests and thermal gravimetric/differential thermal gravimetric analyses. Comparing with the normal expandable graphite (EG, intercalated by single H2SO4), EGb exhibited high dilatability, thermal stability and flame retardancy for LLDPE. It had been testified by combustion tests that the addition of 30 wt % EGb to LLDPE improved the limiting oxygen index (LOI) from17.6% to 30.2%, and the vertical burning level of UL-94 standard reached V-0 level. Whereas, the LOI of the same amount referenced EG was only 25.1%, the UL-94 level only reached V-1. Moreover, the synergistic effect between EGb and ammonium polyphosphate (II) (APP) improved the LOI of 70LLDPE/10APP/20EGb composite to 33.0%, and the UL-94 level to V-0. The synergistic efficiency was attributed to the formation of continuous and compact residual char.
       
  • NEW PHOSPHORUS COMPOUNDS K[PCL3(X)] (X= SCN,
           CN)
    : PREPARATION AND DFT AND SPECTROSCOPIC
           STUDIES

    • Abstract: Two new phosphorus complexes, potassium trichlorothiocyanophosphate (III) (PTCTCP; K[PCl3(SCN)]) and potassium trichlorocyanophosphate (III) (PTCCP; K[PCl3(CN)]) were synthesized from the reaction of KSCN and KCN, respectively, with PC^. The chemical formulas and compositions of these compounds were determined by elemental analysis and spectroscopic methods, such as phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy (31P-NMR), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy and mass spectrophotometry. All of the theoretical calculations and determinations of the properties of these compounds were performed as part of the Amsterdam Density Functional (ADF) program. Excitation energies were assessed using time-dependent perturbation density functional theory (TD-DFT). In addition, the molecular geometry was optimized and the frequencies and excitation energies were calculated using standard Slater-type orbital (STO) basis sets with triple-zeta quality double plus polarization functions (TZ2P) for all of the atoms. The assignment of the principal transitions and total densities of state (TDOS) for orbital analysis were performed using the GaussSum 2.2 program.
       
  • MOLYBDENUM TRIOXIDE THIN FILMS DOPED WITH GOLD NANOPARTICLES GROWN
           BY A SEQUENTIAL METHODOLOGY: PHOTOCHEMICAL METAL-ORGANIC DEPOSITION (PMOD)
           AND DC-MAGNETRON
    SPUTTERING

    • Abstract: Gold nanoparticles (AuNPs) were deposited by DC-magnetron sputtering onto molybdenum trioxide (MoO3) thin films grown by Photochemical Metal-Organic Deposition (PMOD) on Si(100) and borosilicate glass substrates. The chemical, optical and morphology properties of the films were studied by UV/ Vis Spectroscopy, Scanning Electron Microscopy (SEM), X-Ray Photoelectron Spectroscopy (XPS), and X-Ray Diffraction (XRD). SEM revealed that AuNPs formed after 5 s of sputtering. AuNPs are spherical and have both an average diameter of 18 nm and a relatively narrow size distribution. As the deposition time increases, larger structures are formed by an aggregation of AuNPs. XPS studies of the AuNP/MoO3 films on Si(100) showed the presence of Mo(VI) and Mo(V), which indicated that the films were primarily non-stoichiometric molybdenum oxides. The occurrence of oxygen vacancies in the substrate play an important role to stabilize the AuNPs.
       
  • TEMPERATURE EFFECT ON BINDING AFFINITY AND STOICHIOMETRY BETWEEN
           SOME STEROIDS AND HUMAN SERUM ALBUMIN

    • Abstract: The temperature dependence of the interactions between some steroids (fusidic acid, ouabain and ethynodioldiacetate) and human serum albumin (HSA) at physiological pH (7.4) were studied systematically by square-wave voltammetry. Also, these interactions were proven by means of UV-Vis. absorptionspectroscopy and FT-IR spectroscopy techniques. The interaction parameters (binding constants and stoichiometries) at temperature range of 297.5-312.5 K weredetermined from electrochemical data. It is worthy that the temperature has played a positive role on the interactions of fusidic acid with HSA; however it hasnegative effective on the interaction parameters of HSA with ouabain or ethynodioldiacetate.
       
  • CHEMICAL CHARACTERIZATION OF SUB-BITUMINOUS COAL FROM THE ARAUCO
           PROVINCE - CHILE

    • Abstract: The chemical and sorptive characteristics of mineral coals extracted from a mine in Lebu (Biobío Región, Chile) and its derivatives were studied. These derivatives were obtained by applying a thermal treatment in an environment with N2 and CO2 at different experimental conditions, in order to increase their specific surface. In addition, coals were characterized by using proximal analysis, elementary analysis and petrographic analysis. In order to know their structureand surface, Boehm titration analysis, FTIR infrared spectroscopy, X-ray diffraction and scanning electron microscopy were performed. The surface of the selectedcarbons was modified by selectively oxidizing it with (NH^S^O and with H2O2 e impregnating with an iron solution for the study with H2O2 In the oxidation ofH2O2, the work was carried out at different pH. The results show a moderate homogeneity between different types of seams studied, whereas when coals are treatedwith heat or strong oxidants, increases its surface and can be used with analytical applications (v.g. electroanalytical sensors).
       
  • HEAVY METAL CONCENTRATIONS IN WATER AND SEDIMENTS FROM AFFLUENTS
           AND EFFLUENTS OF MEDITERRANEAN CHILEAN RESERVOIRS

    • Abstract: RIVER flows have constant interaction between water and bed sediments; for this reason knowledge of the characteristics of the sediments is fundamental to understand water chemistry. This study determined the concentrations of heavy metals in water and sediments in the affluents and the effluents of the MediterraneanChilean reservoirs Cogotí, Corrales, La Paloma, and Recoleta. We explore possible ecological risk and toxicity using the enrichment factor (EF), risk assessmentcode (RAC), threshold effect concentrations (TEC) and probable effect concentrations (PEC). The results showed that five metals: Al, Fe, Cu, Mn and Zn out of the ten measured metals were detected in both surface water and the sediments. The risk assessment code (RAC) suggested that Fe represents a medium risk in the affluent of Cogotí Reservoir: Cu, Zn and Mn represent a medium to high risk in all the dams and in both zones (affluents and effluents). The enrichment factor(EF) determined that the five metals were lithogenic. Fe, Cu, and Mn are the elements that present the greatest toxicity to microorganisms in these aquatic systems.
       
  • SYNTHESIS AND ANTIMICROBIAL EVALUATION OF SOME NEW ASYMMETRICALLY
           SUBSTITUTED 4-ARYL- 2,6-DI(COUMARINYL) PYRIDINES

    • Abstract: In the present work the synthesis of various 4-aryl-2-(coumarin-3-yl)-6-(4-methyl-3-phenyl coumarin-6-yl)pyridines (6a-i) and 4-aryl-2-(coumarin-3-yl)-6-(4-methyl-7-methoxy coumarin-8-yl)pyridines (7a-i) have been carried out by reacting 1-[2(H)-1-benzopyran-3-yl]-3-aryl-prop-2-en-1-ones (coumarinoyl chalcones) (3a-f) with appropriate coumarinoyl methyl pyridinium bromide salt 4 and 5 respectively. The target compounds were characterized by the IR,J H-NMR, 13C-APT and mass spectral analysis. Preliminary examination of target compounds as antimicrobial agents has been carried out using Broth dilutionmethod.
       
  • HYDROXYCINNAMIC ACID DERIVATIVES AND FLAVONOL PROFILES OF
           MAQUI (Aristotelia chilensis) FRUITS

    • Abstract: Maqui (Aristotelia chilensis) is an edible berry native to Southern Chile. The anthocyanin profiles and concentrations of this fruit have been widely studied. The high concentration of anthocyanins confers a deep colour to the skin and pulp of maqui berries, and the biological activity of this fruit has been attributed to these compounds. However, other compounds such as flavonols and hydroxycinnamic acid derivatives in this fruit have not been studied to date. The objective was to determine the hydroxycinnamic acid derivatives and flavonol profiles in maqui berries in order expand the knowledge base for this fruit. Two extraction methodologies (solid phase extraction using a mixed mode cation exchange cartridge and selective precipitation), followed by HPLC-DAD-ESI-MS/MS were applied to the extraction and identification of the main hydroxycinnamic acids and flavonols in the berries. Quantification was accomplished by using the first extraction procedure. Low levels of hydroxycinnamic acid derivatives were detected in maqui berries, where 5-galloylquinic acid was the only quantifiable derivative. However, diverse and high levels of flavonols were detected in the fruit, the most relevant of which are myricetin-galactoside, quercetin-rutinoside, and quercetin-3-galactoside. Nineteen other flavonols were identified, with total concentrations between 1.05 and 1.18 μmol/g fresh weight. The diversity of flavonols makes the profiles and concentrations of these compounds significant, whereas hydroxycinnamic acids in maqui are not significan! The comparatively high levels of flavonols combined with the high concentration of anthocyanins contribute to the consideration of this native fruit from Chileas a "superfruit".
       
  • SiO2@FeSO4 NANO COMPOSITE AS NANOCATALYST
           FOR THE GREEN SYNTHESIS 1,1-DIACETATES FROM ALDEHYDES UNDER SOLVENT-FREE
           CONDITIONS

    • Abstract: Aldehydes compounds selective converted to 1,1-diacetates as protective reagent with SiO2@FeSO4 nano composite as effective nano catalyst at room temperature under solvent-free condition and acetic anhydride (Ac2O) as acetylation reagent. This method provides several advantages, such as low cost of the nano catalyst, high yields, short reaction time, chemoselective protection of aldehydes and operational simplicity. Aromatic and aliphatic, simple and conjugatedaldehydes were protected with excellent yields. In addition, chemoselective reductive acetylation of aldehydes over ketones was achieved perfectly with the reagent at room temperature.
       
  • BRANCHED POLYESTERS FROM GERMYLATED AND FATTY COMPOUNDS

    • Abstract: Here we report the synthesis of news branched polyesters derived from the trans-esterification reactions at modérate temperatures (140-190°C), either from polyglycols with different molecular weights and monomers such as germylated fatty tri-esters, or from dimethyl terephtalate and germylated fatty tri-alcohol.The structure of the resulting polymers was determined by elemental analysis, FTIR, and 13C CP MAS NMR, and their thermal properties by the rmogravimetry analysis and differential scanning calorimetry. 13C CP MAS NMR analysis indicates that the characteristic signals due to the methoxy groups of the germylatedfatty tri-ester and the CH2OH group of germylated fatty tri-alcohol completely disappeared. This suggests that the trans-esterification process reached a nearlycomplete conversion. All germylated branched polyesters are insoluble in classic organic solvents due to their polydimensional structure. Thermal properties of these new materials showed that they do not present any cristallinity phase, and undergo thermal decomposition above 300°C.
       
  • FAST AND RELIADLE METHOD FOR MONITORING EPOXIDATION REACTION IN
           RECYCLED VEGETABLE OILS (ERVO) USING FTIR-ATR TECHNIQUE

    • Abstract: The present study focuses on the deficient learning of health science students in the General Chemistry course in the first level higher education, specifically regarding the topic of aqueous dissolutions in terms of the meaning of pH and how to determine it. The causes of this problem are: i) the difficulty relating the theory to the practice, ii) the lack of strategies that help and motivate learning, iii) the inability to underst and and resolve problems or exercises, and iv) a deficiencyon basic mathematical aptitudes for application in resolving problems and exercises, among others. The research considered the academic results obtained bystudents of various careers in the area of health sciences students in the past, to subsequently determine the research group, resulting it the career of nursingstudents. To achieve this type of learning, the Zone of Proximal Development (ZPD) was applied, together with the metacognitive strategy of Conceptual Maps (CM) and feedback & self-correction in practical laboratory activities. This study was carried out at a university and involved nursing students because they havemany difficulties learning experimental sciences, especially chemistry, because the students of other careers do not have many weaknesses in this science, beingevidenced in the results at end of the semester-The sample experimental group consisted of 336 nursing students and the control group 420 students of nutrition and dietetics and dentistry taking the unit "General Chemistry", who provided all the information for this study.
       
  • ARSENIC SORPTION USING MIXTURES OF ION EXCHANGE RESINS CONTAINING
           N-METHYL-D-GLUCAMINE AND QUATERNARY AMMONIUM GROUPS

    • Abstract: The method of synthesis and the arsenie removal properties of ion-exehange resins based on N-methyl-D-glueamine and trimethylammonium groups are presented. The N-methyl-D-glueamine based monomer was synthesized by the reaetion of 4-vinyl benzyl ehloride with N-methyl-D-glueamine, along with theuse of N,N-methylene-bis-aerylamide as a erosslinker reagent for polymerization. In addition, poly(4-vinylbenzyl)trimethylammonium was synthesized. Arsenatesorption studies were conducted and the pH effect, kinetics, sorption capacity, and elution performance were studied. The experimental data were fitted to kineticmodels, such as the pseudo-first order and pseudo-second order models. The pseudo-second order model exhibited the best correlation with the experimental data.The Langmuir and Freundlich isotherms were fitted to the experimental data, and the Freundlich isotherm exhibited the best fit.
       
  • CHEMISTRY LEARNING WITH APPLICATION OF THE ZONE OF PROXIMAL
           DEVELOPMENT AND USE OF CONCEPTUAL MAPS IN THE CHEMISTRY LAB

    • Abstract: The present study focuses on the deficient learning of health science students in the General Chemistry course in the first level higher education, specifically regarding the topic of aqueous dissolutions in terms of the meaning of pH and how to determine it. The causes of this problem are: i) the difficulty relating the theory to the practice, ii) the lack of strategies that help and motivate learning, iii) the inability to underst and and resolve problems or exercises, and iv) a deficiencyon basic mathematical aptitudes for application in resolving problems and exercises, among others. The research considered the academic results obtained bystudents of various careers in the area of health sciences students in the past, to subsequently determine the research group, resulting it the career of nursingstudents. To achieve this type of learning, the Zone of Proximal Development (ZPD) was applied, together with the metacognitive strategy of Conceptual Maps (CM) and feedback & self-correction in practical laboratory activities. This study was carried out at a university and involved nursing students because they havemany difficulties learning experimental sciences, especially chemistry, because the students of other careers do not have many weaknesses in this science, beingevidenced in the results at end of the semester-The sample experimental group consisted of 336 nursing students and the control group 420 students of nutrition and dietetics and dentistry taking the unit "General Chemistry", who provided all the information for this study.
       
  • PHENOLIC COMPOSITION AND BIOLOGICAL (ANTI DIABETIC AND
           ANTIOXIDANT) ACTIVITIES OF DIFFERENT SOLVENT EXTRACTS OF AN ENDEMIC PLANT
           (HELIOTROPIUM STRIGOSUM)

    • Abstract: Heliotropium strigosum plant is widely used in traditional medicines for treatment of various ailments. In current study, an effort was made to evalúate phenolic profile as well as antidiabetic and antioxidant activities of crude methanol extract and different solvent (n-hexane, ethyl acetate, chloroform and aqueous) fractions of H. strigosum. Total phenolic contents were determined by spectrophotometric assay. Polyphenolic compounds in crude methanol extract and each solvent fraction were identified by reverse phase high performance liquid chromatography (RP-HPLC). Antioxidant and antidiabetic activities were determined using DPPH and a-amylase inhibition assays, respectively. The outcome of spectrophotometric assay showed that methanol extract had higher amount of total phenolic (84.50 ± 0.06 pg GAE/ mg of plant extract) contents than aqueous, ethyl acetate, chloroform and n-hexane fractions, respectively. The RP-HPLC analysis revealed the maximum number of phenolic (chromotropic acid, quercetin, trans-4-hydroxy-3-methoxy cinnamic acid, vanillic acid, gallic acid, caffeic acid, m-coumaric acid, p-coumaric acid, syringic acid, sinapic acid and ferulic acid) compounds in methanol extract. Methanol extract (IC5(0) = 8.97 pg/mL) exhibited the maximum antidiabetic activity followed by aqueous (IC50 = 20.04 pg/mL), ethyl acetate (IC50 = 27.79 pg/mL), chloroform (IC50 = 56.87 pg/mL) and hexane (IC50 = 32.16 pg/mL) fractions, respectively. The outcome of antioxidant assay revealed that methanol extract was the leading one with regard to antioxidant activity at different doses (10 to 250 pg/mL). The current study concludes that H. strigosum solvents extracts with significant phenolic profile and potent biological activities could be explored for potential uses in neutraceutical and pharmaceutical industries.
       
  • STUDY OF THE REMOVAL OF 4-NITROPHENOL FROM AQUEOUS MEDIA BY
           ADSORPTION ON DIFFERENT MATERIALS

    • Abstract: The removal of 4-Nitrophenol (4-NP) from aqueous media by adsorption is studied in a batch system using different porous materiais: activated carbón, zirconia, alumina, sepiolite, natural zeolite and 13X zeolite. Depending on their adsorption capacities, the best adsorbent was chosen to be impregnated withdifferent levels of nickel (Ni) in order to study the adsorption by n-complexation in batch and continuous systems. The samples of Ni(x)/support (x= 2, 4, 6%)were prepared by wet impregnation and were characterised using the same method as with all the materials, by N2 adsorption-desorption using the BET method,surface acidity and Z potential measurements by electrophoretic migration. The samples were measured in a UV-Vis electrophotometer at a wavelength of 318nm, while the adsorption capacity of the material in the batch system was determined by calculating the difference in concentration once the adsorbent becamesaturated after an initial concentration of ~20 ppm, and in the continuous system this was done by integrating the area under the adsorption curve. The resultssuggest that adsorption capacity depends on the specific BET area, apparent acid strength and the IEP of each support, and that it varies with the addition of Ni.
       
  • DEVELOPMENT OF AN ANALYTICAL METHOD FOR THE MAIN ORGANIC COMPOUNDS
           DERIVED FROM THERMOCHEMICAL CONVERSION OF BIOMASS

    • Abstract: In this work, high-performance liquid chromatography (HPLC-UV/RID) is applied to the simultaneous determination of acetic acid, formic acid, acetol, glyoxal, glycolaldehyde and levoglucosan in a by-product in an aqueous liquid phase that is produced by the Hydrothermal Carbonization (HTC) process and inan aqueous bio-oil phase, which comes from a fast pyrolysis process. Both processes were run in forest biomass. For the development and optimization of the proposed method, some chromatographic columns were evaluated based on separation principles of reversed phase and ionic exclusion, although it was previously performed with a solid phase extraction (SPE) process. Concentrations of acetic and formic acids in the liquids of the HTC process ranged from 0.26 to 1.5 % and from 0.14 to 2.7 %, respectively. Concentrations of acetic and formic acids, levoglucosan and glycolaldehyde in the aqueous bio-oil phases ranged from 0.4 - 4.6 %, 0.4 - 1.4 %, 0.13 - 2.5 % and 0.5 - 3.5%, respectively.
       
  • RECYCLABLE ACIDIC BR0NSTED IONIC LIQUID CATALYZED SYNTHESIS OF
           QUINOXALINE

    • Abstract: The acidic ionic liquid, 1-(4-sulfonic acid) butyl-3-methylimidazolium hydrogen sulfate [MimC4SO3H]HSO4 catalyzed two-component condensation reaction of phenacyl bromide and o-phenylenediamine to afford corresponding quinoxaline derivatives. The inexpensive and non-toxic ionic liquids can be reused severaltimes without any perceptible loss of their activities.
       
  • SENSITIVE SIMULTANEOUS DETERMINATION OF PARACETAMOL AND DICLOFENAC
           BASED ON Au NANOPARTICLES - FUNCTIONALIZED GRAPHENE/POLY (L-ARGININE)
           GLASSY CARBON ELECTRODE

    • Abstract: A voltammetric sensor was proposed for simultaneous determination of paracetamol and diclofenac based on poly (L-arginine)/Au-graphene nanocomposite film deposited on a glassy carbon electrode. Cyclic voltammetry showed that paracetamol and diclofenac provided well - defined oxidation peaks at +0.443 and +0.644 V, respectively. Experimental parameters, such as the concentration of L-arginine and number of potential cycles in electro-polymerization step,accumulation potential and time, and the pH of buffer solution were optimized. Under the optimized conditions, linear relationships between oxidation peak current and concentration in the range 0.5 - 50.0 pM for paracetamol, and 0.5 - 40.0 pM for diclofenac were obtained in linear sweep voltammetry regime. The limits of detection (LOD) for paracetamol and diclofenac were 0.04 and 0.08 pM, respectively. The fabricated electrode exhibited good reproducibility and stability.The proposed method was successfully applied to the assessment of low concentrations of paracetamol and diclofenac in spiked human blood serum samples withsatisfactory results.
       
 
 
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