18 research outputs found

    Erratum Analysis of the physical and photoelectrochemical properties of c Si p a SiC H p photocathodes for solar water splitting

    Get PDF
    The photoelectrochemical (PEC) properties of sputtered aluminum doped hydrogenated amorphous silicon carbide thin films grown on p-type crystalline silicon substrates were investigated in 1 M H2SO4<i solution under chopped light illumination. Optical and structural properties of the top absorber layer were systematically assessed after post-deposition isochronical annealing treatments. Samples exhibited a noticeable improvement of the opto-electronic properties after thermal treatments. In addition, an abrupt enhancement of the photocurrent was observed reaching a saturation value of 17 mA cm(-2) at -1.75 V vs. Ag/AgCl (3.5 M KCl). In this research we propose that this enhancement effect is associated to a charge transfer kinetic mechanism influenced by surface states and the p-type substrate. The latter most likely due to the space charge region extending beyond the absorber layer reaching the substrate. Current density-potential and electrochemical impedance spectroscopy measurements in dark revealed a reduction of the SiO2 native layer at cathodic potentials higher than -1 V vs. Ag/AgCl (3.5 M KCl), which contributes to the high charge transfer kinetic of the system. We believe that these results will contribute to understand the substrate influence in the PEC performance of top absorber layers in multilayer structures for solar water splitting.This research was funded by FONDECYT (National Fund for Scientific, Technological Development and Technological Innovation) under the agreement 147-2017. The author M Mejia has been supported by the CONCYTEC Peru (National Council for Science, Technology and Technological Innovation) doctoral scholarship under the Contract Number 236-2015-FONDECYT as well as by the PUCP vicechancellorship for research (VRI, Project No. CAP-2019-3-0041/702). The authors would like to thank the Katholischer Akademischer Auslander-Dienst institution (KAAD) for the short-term grants given to conduct research internships in the Technische Universitat Ilmenau (TU Ilmenau). Finally, the authors would like to thank the German Research Foundation (DFG) (DFG-Gz: INST 273/56-1 FUGG) and the Materials Characterization Center (CAM) at PUCP, for the financial support to conduct the characterization experiments

    Traditional medicinal plant use in Northern Peru: tracking two thousand years of healing culture

    Get PDF
    This paper examines the traditional use of medicinal plants in Northern Peru, with special focus on the Departments of Piura, Lambayeque, La Libertad, Cajamarca, and San Martin. Northern Peru represents the center of the old Central Andean "Health Axis," stretching from Ecuador to Bolivia. The roots of traditional healing practices in this region go at least as far back as the Moche period (AC 100–800). Although about 50% of the plants in use reported in the colonial period have disappeared from the popular pharmacopoeia, the plant knowledge of the population is much more extensive than in other parts of the Andean region. 510 plant species used for medicinal purposes were collected, identified and their vernacular names, traditional uses and applications recorded. The families best represented were Asteraceae with 69 species, Fabaceae (35), Lamiaceae (25), and Solanaceae (21). Euphorbiaceae had twelve species, and Apiaceae and Poaceae 11 species. The highest number of species was used for the treatment of "magical/ritual" ailments (207 species), followed by respiratory disorders (95), problems of the urinary tract (85), infections of female organs (66), liver ailments (61), inflammations (59), stomach problems (51) and rheumatism (45). Most of the plants used (83%) were native to Peru. Fresh plants, often collected wild, were used in two thirds of all cases, and the most common applications included the ingestion of herb decoctions or the application of plant material as poultices

    fisheries and tourism social economic and ecological trade offs in coral reef systems

    Get PDF
    Coastal communities are exerting increasingly more pressure on coral reef ecosystem services in the Anthropocene. Balancing trade-offs between local economic demands, preservation of traditional values, and maintenance of both biodiversity and ecosystem resilience is a challenge for reef managers and resource users. Consistently, growing reef tourism sectors offer more lucrative livelihoods than subsistence and artisanal fisheries at the cost of traditional heritage loss and ecological damage. Using a systematic review of coral reef fishery reconstructions since the 1940s, we show that declining trends in fisheries catch and fish stocks dominate coral reef fisheries globally, due in part to overfishing of schooling and spawning-aggregating fish stocks vulnerable to exploitation. Using a separate systematic review of coral reef tourism studies since 2013, we identify socio-ecological impacts and economic opportunities associated to the industry. Fisheries and tourism have the potential to threaten the ecological stability of coral reefs, resulting in phase shifts toward less productive coral-depleted ecosystem states. We consider whether four common management strategies (unmanaged commons, ecosystem-based management, co-management, and adaptive co-management) fulfil ecological conservation and socioeconomic goals, such as living wage, job security, and maintenance of cultural traditions. Strategies to enforce resource exclusion and withhold traditional resource rights risk social unrest; thus, the coexistence of fisheries and tourism industries is essential. The purpose of this chapter is to assist managers and scientists in their responsibility to devise implementable strategies that protect local community livelihoods and the coral reefs on which they rely

    Indice de aminoácidos libres y estructuras celulares como indicadores de calidad en jugos de fruta

    No full text
    Two parameters not considered as paradigms for quality control of natural fruit juice in the Peruvian Technical Norms are studied here. These parameters a) free amino acid index (FAI) and b) ceIlular structures (CE), would contribute with quantitative and qualitative data to evidence genuinely and quality. In 11 juices prepared at lab level according to pH, acidity and soluble solids specifications and of high consume (peach, strawberry, mandarin orange, mango, apple, maracuya, orange, melon, pear, pineapple and grape) it has been determined: A) the microscopic cellular characteristics (WaIlis metbod) and b) free amino acid index, by means of the formalin index (an A.O.A.c. official method). The same parameters were analyzed in 18 rmnufactured tradermrk juices that are commercialized in the country. This result is reported graphically in photographs taken at tbe moment of CE microscopic observation and values reported in tables submitted to statistical analysis. These ones indicate that the formalin index, expressed as a free amino acid index in the presence of cellular structures, is independent (r= 0,2587) and tbat in absence of cellular structures, the free amino acid index acquires a confirmative character about the genuinely of the raw materials employed in juice manufacture. In manufactured juices, quantifiable amounts of aminic nitrogen are reported, although these values are below tbe ones obtained with laboratory prepared fruit juices.Se estudian dos parámetros que,en las Normas Técnicas Peruanas a consultar (ITINTEC), no se han considerado como paradigmas para el control de calidad de jugos de frutas naturales. Estos parámetros: a) índice de aminoácidos libres (IAL) y b) las estructuras celulares (EC) nos aportarían datos cuantitativos y cualitativos para evidenciar genuinidad y calidad. En 11 jugos, preparados a nivel de laboratorio (durazno, fresa, mandarina, mango, manzana, maracuyá, melón, naranja, pera, piña y uva) se ha determinado: a) Sus características celulares microscópicas (método de Wallis) y el b) Indice de aminoácidos libres, a través del índice de formol método oficial de la AOAC .También se aplicaron estos parámetros a 18 jugos industrializados de marcas que se comercializan en el país. Estos resultados se reportan gráficamente en fotografías tomadas al momento de la observación microscópica de sus EC y en cuadros cuyos valores han sido sometidos a análisis estadísticos. Estos indican que el índice de formol, expresado como IAL y la presencia de EC son independientes ( r= 0,2587) y que en ausencia de EC, el Índice de formol adquiere un carácter confirmatorio acerca de la genuinidad de la materia prirm empleada en la elaboración de jugos. En los jugos industrializados se reportan cantidades dosables de nitrógeno aminico, aunque los valores están por debajo de los obtenidos a partir de jugos de fruta preparados en laboratorio

    Aceptación de medicamentos genéricos por usuarios de sectores C, D y E en tres zonas de Lima

    Get PDF
    The aim of this research was to determine the acceptability of generic drugs (GD) among users that belong to the sectors C, D and E in Metropolitan Lima, as well as the grade of knowledge, confidence and possible barriers in its consumption. A survey was conducted in zones where over than the 85% of the population belongs to this sectors .The tool consisted in a questionnaire of 11 open and closed questions. It was identified four dimensions that influenced on the acceptance of the generic drugs: information, security/efficacy, consumption and access. The analysis of the results obtained by the scale of Stanones set the media average of 3,2 among the four dimensions whichs means a REGULAR dimension. It was found a high consumption of GD with a media of 4,9; this accessibility is linked to the low cost instead than confidence in the GD, since there are doubts about its efficiency.Esta investigación tuvo como objetivo determinar el grado de aceptación de medicamentos genéricos (MG) por parte de usuarios pertenecientes a los sectores C, D y E, de tres zonas de Lima Metropolitana, así como el grado de conocimiento, confianza y las posibles barreras en su consumo; para ello se aplicó una encuesta en las zonas donde más del 85% de la población pertenece a estos sectores socio-económicos. El instrumento fue un cuestionario de 11 preguntas abiertas y cerradas. Se identificaron cuatro dimensiones que influyen en la aceptación de los medicamentos genéricos: información, seguridad/eficacia, consumo y acceso. El análisis de los resultados obtenidos por la escala de Stanones, estableció una media promedio de 3,2 entre las 4 dimensiones, lo que se interpreta como una dimensión REGULAR. Se encontró un alto consumo de medicamentos genéricos, con una media de 4,9; accesibilidad ligada más a la capacidad económica que a la confianza hacia este tipo de medicamento, pues existen dudas sobre su seguridad y eficacia

    Analysis of the physical and photoelectrochemical properties of c Si p a SiC H p photocathodes for solar water splitting

    Get PDF
    The photoelectrochemical PEC properties of sputtered aluminum doped hydrogenated amorphous silicon carbide thin films grown on p type crystalline silicon substrates were investigated in 1 M H2SO4 solution under chopped light illumination. Optical and structural properties of the top absorber layer were systematically assessed after post deposition isochronical annealing treatments. Samples exhibited a noticeable improvement of the opto electronic properties after thermal treatments. In addition, an abrupt enhancement of the photocurrent was observed reaching a saturation value of 17 mA cm amp; 8722;2 at amp; 8722;1.75 V vs. Ag AgCl 3.5 M KCl . In this research we propose that this enhancement effect is associated to a charge transfer kinetic mechanism influenced by surface states and the p type substrate. The latter most likely due to the space charge region extending beyond the absorber layer reaching the substrate. Current density potential and electrochemical impedance spectroscopy measurements in dark revealed a reduction of the SiO2 native layer at cathodic potentials higher than amp; 8722;1 V vs. Ag AgCl 3.5 M KCl , which contributes to the high charge transfer kinetic of the system. We believe that these results will contribute to understand the substrate influence in the PEC performance of top absorber layers in multilayer structures for solar water splittin

    Indirect excitation and luminescence activation of Tb doped indium tin oxide and its impact on the host s optical and electrical properties

    No full text
    The effect of adding terbium to indium tin oxide ITO thin films on the electrical, optical and light emission properties was investigated. The films were prepared by radio frequency dual magnetron sputtering, maintaining a high optical transmittance in the ultraviolet and visible spectral regions, and a low electrical resistivity ranging from 5 10 amp; 8722;3 amp; 937; cm to 0.3 amp; 937; cm. Terbium related luminescence is achieved after annealing at 470 amp; 9702;C in air at atmospheric pressure. Electrical resistivity and optical transmittance were measured after each annealing step to evaluate the compromise between the achieved light emission intensity, electrical and optical properties. Additionally, temperature dependence of Tb related luminescence quenching was assessed by temperature dependent photoluminescence measurements, from 83 to 533 K, under non resonant excitation. Thermal quenching activation energies suggest an effective energy transfer mechanism from the ITO host to the rare earth RE ions. This indirect excitation mechanism was modeled using a spherical potential well and a tight binding one band approximation approaches, describing a short range charge trapping process and subsequent formation of bound excitons to RE ion cluster

    Detección de casos de Tuberculosis en escolares del Colegio Nacional «Jorge Basadre Grohmanm» del P.J. «El Independiente» - El Agustino-Lima, Perú

    No full text
    The objectives of the present investigation were to deted cases of pulmonary tuberculosis and to determine the prevalence rate between subjects: 776 students with ages between 5 and 18 years old, of both genders. We divided them in two groups: A) to 193 boys up to 7 years old,who were applied the PPD test. If the papule were greater or equal to of 10 mm. in diameter, the students were submitted to a radiological examination and sputum test. Positive casespassed a clinical examination. B) Students that were older than 7 years (n=573), were applied an epidemiological survey. The positive ánswers to cough for more than 15 days, fever, sweat, loss weight or being in clase contact with sick people of TBC, were categorized as a respiratory symptomatic ethiology ; the confirmation was made using baciloscopy technique. The diagnosed cases as positive were incorporated to the Health Department National Program of Tuberculosis Control. At the same time, it was carried out a study of socio economica1 conditions of the community; 9 cases were detected (4 males and 5 females) with ages between 6 and 14 years old that represents the prevalence rate of 1,15% making the study group, a population at higher risk.Between the major prevalent socio economical conditions we have: lack of basic services, 70% of the population in working age is unemployed or sub employed and ingest diets with inadequated protein content.The impact of this study is the evidence of a problem, where many sectors oí society publish TBC as a controlled disease but is impossible ta affirm such statement due to an increase of drug resistence of the bacteria.Los objetivos del presente estudio fueron detectar los casos de tuberculosis pulmonar y determinar el porcentaje de prevalencia entre 776 estudiantes de ambos sexos, comprendidos entre los 5 a 18 años de edad. Los mismos (estudiantes) que fueron divididos en 2 grupos:a) 193 niños no mayores de 7 años, a los cuales se les aplicó la prueba del PPD; si el diámetro de la pápula fue de 10 mm o más, los estudiantes fueron sometidos a un examen de Rx y examen de esputo. En los casos positivos, se requirió un examen clínico del paciente.b) Los otros del grupo mayores de 7 años (n = 573), se les solicitó una encuesta epidemiológica. Las respuestas positivas de: toser más de 15 días, fiebre, sudoración, pérdida de peso o estar cerca de enfermos de TBC; fueron categorizados como pacientes con etiología respiratoria sintomática; la prueba confirmatoria fue realizada por técnica de baciloscopía.Los casos diagnosticados como positivos fueron incorporados al Programa Nacional de Control de TBC del Ministerio de Salud. Al mismo tiempo se llevó a cabo un estudio de las condiciones socioeconómicas de la comunidad: fueron detectados 9 casos (4 hombres, 5 mujeres), cuyas edades fluctuaban entre 6 y 14 años de edad que representa un porcentaje de prevalencia de 1,15%. que los coloca en el estudio, como una población de alto riesgo.Entre las condiciones socioeconómicas se encontraron: ausencia de servicios básicos, el 70% de la población económicamente activa (PEA) está desempleada o subempleada y la dieta que ingiere es inadecuada en contenido proteico.El impacto de este estudio evidencia el problema que muchos sectores de la sociedad consideran que la TBC está controlada; pero, sin embargo la resistencia de muchas drogas tuberculostáticas que van en aumento hacen que esta enfermedad aún no desaparezca de nuestro medio

    Evaluación del uso de antimicrobianos de reserva por pacientes hospitalizados en establecimientos de salud

    No full text
    It is a of drugs utilization, descriptive, transversal, observational, multicentric study that follows a transversal design, prescription type -indication- with the aim to determine the prevalence use of reserve antimicrobials in hospitalized patients, of all age groups, men and women in services of internal medicine. We applied two sheets of data collection: ATMR-S (for services) and ATMR-P (for patients) to obtain prevalence of reserve antimicrobials (ATMR) and the ATMR prescribed. The sheets were implemented on August 21, 2006 to 845 patients thatwerc hospitalized that day. Wereport an overall prevalence of ATMR prescribing by hospitals is 28%, with extreme values rangingfrom 18% to 38%; theprevalence of use by services is 32.3% with values ranging from 16.4% in obstetrics-gynecology, and 57.1 % in the intensive care unit. ATMR are the most prescribed according to hospital are vancomycin 500 mg. Injection and ceftazidime 1g. with 41.7% in the Guillermo Almenara Hospital and Dos de Mayo respectively; in the Naval Medical Center, 50% of patients of the medicine service was treated with ciprofloxacin 500 mg. Slotted tablet; in the Hospital of the National Police it was prescribed ceftriazone 1g. injection and vancomycin 500 mg.injection by 36%, and 100% of patients treated with ceftriozona 1g. injection. In general, these values are significantly lowerw with ATM in general (60%), but would have to continue monitoring to determine the impact of their use.Es un estudio de utilización de medicamentos, descriptivo, transversal, observacional, multicentrico, tipo prescripción - indicación, cuyo objetivo de determinar la prevalencia de uso de los antimicrobianos de reserva (ATMR) por pacientes hospitalizados, de todos los grupos etáreos, varones y mujeres, en los servicios de medicina interna, cirugía, pediatría, gineco- obstetricia y Unidad de Cuidados intensivos de 5 hospitales de Lima. Se aplicaron dos fichas de recolección de datos: ATMR-S (para servicios), y ATMR-P (para pacientes) con el fin de obtener la prevalencia de uso de antimicrobianos de reserva (ATMR) y los ATMR prescritos. Las fichas se aplicaron el día 21 de agosto del 2006, a 845 pacientes que ese día estaban hospitalizados. Se reporta una prevalencia global de prescripción de ATMR de 28%, con valores extremos que van del 18%, hasta 38%; la prevalencia de uso por servicios es de 32.3% con valores que fluctúan entre 16.4 % en Gineco obstetricia y 57.1 % en la Unidad de cuidados intensivos. Los ATMR más prescritos de acuerdo al hospital son la Vancomicina 500 mg. inyectable y ceftazidima 1 g inyectable con 41.7% en los hospitales Guillermo Almenara y Dos de Mayo; en el Centro Médico Naval, el 50% de pacientes del servicio de medicina fue tratado con ciprofloxacino 500 mg. Tableta ranurada; en el Hospital PNP se prescribió ceftriozona 19 inyectable y Vancomicina 500 mg. inyectable en el 36% y el 100% de pacientes recibió ceftriozona 1g inyectable.En general, las cifras halladas son significativamente mas bajas respecto al uso de antimicrobianos en general, pero habría que continuar con el monitoreo para precisar el impacto de su uso
    corecore