National University of San Marcos
Recent publications
Microturbellarians are all mostly small free-living Platyhelminthes that do not belong to either the Polycladida or Tricladida order. This group includes species of the clades Catenulida and Rhabditophora. Species of microturbellarians are known to live in marine and continental waters such as rivers, where they are diverse and abundant. However, there are few records of microturbellarians in most of the rivers of the Pacific slope of Peru. Here, we report eight species of microturbellarians from the Chillón River, in the central region of Peru. Of the total species recorded, five (Gieysztoria cuspidata, G. bellis, Myostenostomum vanderlandi, Stenostomum tuberculosum and S. saliens) represent the first reports on the Pacific slope of the Neotropical region in Peru, thereby increasing the diversity of microturbellarians in this country.
We present the magnetic, structural and ⁵⁷Fe Mossbauer characterization of soils collected from an ancient mercury contaminated city named Huancavelica in Peru. The characterization results indicate that silicates and carbonates are the main mineralogical constituents in the samples. In addition, ⁵⁷Fe Mössbauer spectra at room temperature reveal, the presence of two components: a magnetic component related to magnetic Fe-oxides (magnetite, hematite, goethite) and a high non-magnetic component related to Fe⁺³ in high spin configuration and tetrahedral coordination in silicates. The magnetization measurements present screening of paramagnetic, ferromagnetic and antiferromagnetic signals, typical from soils containing different silicates and iron minerals. Remarkably the Verwey and Morin transitions corresponding to magnetite and hematite, respectively, are screened by the paramagnetic signal corresponding to the major silicate components in the samples. Overall, the soils are mainly composed of crystalline and amorphous silicates, calcites and iron bearing which are typical from Andean soils.
The primary process in an electrical arc furnace (EAF) during industrial steelmaking results in tons of black slags which cause pollution to the environment. In this work, the iron oxides of black slags generated in the EAF from the SIDERPERU plant, Peru was reduced via the carbothermal reaction. The reduction of the black slag to α-Fe is demonstrated by X-ray diffraction, Mӧssbauer spectroscopy and magnetometry. However, phases with calcium and silicon persist in the sample after the carbothermal process. The thermodynamic calculations of the most probable reactions sequence were performed to understand the reduction process. The magnetometry measurements confirm the presence of ferromagnetic domains, supporting the success of the reduction of the black slag to α-Fe. The reduced black slags were recycled into a HRB335 steel rod by consolidation and extrusion processes and inspected by X-ray fluorescence.
Nowadays there is a high interest in the recovery of industrial steel waste into useful by-products. For that purpose, it is important to know the physical and chemical properties of steel slag in order to better understand its characteristics and thus seek applications. In this work, we study primary steel slag formed in an electric arc furnace (EAF). Here we present the structural characterization and magnetic properties of the slag performed by X-ray fluorescence spectroscopy (XRF), X-ray diffractometry (XRD), scanning electron microscopy (SEM), magnetic measurements and Mössbauer spectroscopy. The elements Zn, Fe, Cl, Ca, and K and the phases Fe3O4, Zn5(OH)8Cl2.H2O, ZnO, and KCl were identified by XRF and XRD, respectively. Mössbauer spectroscopy at room temperature shows one doublet typical for Fe²⁺, and sextets corresponding to Fe3O4, and Fe2O3. ⁵⁷Fe-Mössbauer spectroscopy appears as a necessary tool in metallurgical slag research.
The steel industry produces large amounts of slag coming from different stages during the steelmaking process every year. Currently, there are numerous attempts to recycle it or to use it in some other industry sectors and to preserve the environment. The characteristics of the slag depends on the steelmaking process and it is crucial to have it before any attempt of recycling. In this work, slag sample produced in the ladle furnace from SIDERPERU steel plant were collected and analyzed by using energy dispersion X-ray (EDX), X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), SQUID magnetometer and Mössbauer spectroscopy. The chemical analysis obtained by EDX and XRF indicate that the main elemental composition of the material is Fe, Ca, Si and Cr. XRD identifies that these elements are in the phases: FeO, Fe3O4, α-Fe2O3, Ca2SiO4, and Ca2,32Mn0,68SiO7. Magnetometry measurements suggest the Verwey transition for magnetite and the Morin transition for hematite are screened by the presence of superparamagnetic phases. The Mössbauer spectrum shows two doublets related to Fe²⁺ and Fe³⁺ ions with hyperfine parameters belonging to that of non-stoichiometric wustite. Also, the presence of hyperfine fields characteristic of the Fe3O4 and Fe2O3 phase identified at room temperature verifies the magnetometry analysis. The analysis of the sample used in this work reveals details connected with the steel fabrication processes and are helpful for posterior recycling attempts.
Every year, the steelmaking industry produces millions of tons of slags resulting in pollution to the environment. Among the waste, secondary metals and scales rich in iron oxides are also thrown away. There is a need to treat the steel waste in a reasonably way to protect the environment and proposing new cheap technologies for producing advanced materials. In this study we report the morphological and structural characterization of waste scales generated during roll milling steel process at JSC “Arcelor Mittal Temirtau”. The raw slag and annealed at 1000 °C were measured by X-ray diffraction (XRD), scanning electron microscopy adapted with energy dispersive X-ray (SEM- EDX), magnetometry and Mössbauer Spectroscopy (MS). Fe and O were detected by EDX as main chemical elements and Si, S, Ca, Mg, C and Al as minimal elemental composition. XDR for the raw sample revealed α-Fe 2 O 3 (hematite) and Fe 3 O 4 (magnetite) as principal and secondary phase, respectively; whereas monophasic α-Fe 2 O 3 is detected for the scales annealed at 1000 °C. Magnetometry measurements show the Verwey transition for the raw sample and the Morin transition for the annealed at 1000 °C; those are fingerprints for the presence of magnetite and hematite, respectively. MS measurements for the raw sample consist of 6 small peaks of absorption and a broad two-lines absorption peak in the central part. The doublets are associated to the hyperfine parameters belonging to wustite. Magnetite is related to the hyperfine parameters for two sextets in octahedral Fe 2.5+ and tetrahedral Fe ³⁺ sites and a small sextet that resembles the Mössbauer parameters of α-Fe 2 O 3 . Only a well crystallized and weakly ferromagnetic sextet confirm the presence of α-Fe 2 O 3 phase for the sample annealed at 1000 °C due to thermal oxidation.
Carbonatite is an igneous rock that is composed mainly of carbonate minerals and silicates. It is recently applied as fertilizer due to its high content of calcite and dolomite. This study presents a physical and chemical characterization of the Spanish River Carbonatite (SRC) and its application as fertilizer is tested. The chemical composition obtained by X-ray fluorescence and Energy Dispersive X-ray analyses indicates that Ca, Fe and Si are the main contained elements. Calcite and SiO2 are the principal mineralogical phases as detected by X-ray diffraction. Fourier transform infrared spectroscopy confirms the presence of calcite, silicates and also organic material and water. It also suggests the presence of vermiculite. Thermal analysis reveals only a one-step reaction that corresponds to the decomposition of calcite. Mössbauer spectroscopy performed at room temperature do not show magnetic order between the iron moments instead it shows Fe²⁺ and Fe³⁺ doublets in M1 and M2 octahedral sites belonging to vermiculite. At 50 K, we observe that the isomer shift increases their values due to the second order Doppler shift. SQUID magnetometry measurements reveal that most of the sample contains paramagnetic domains assigned to the silicates and calcite components. However, under low applied fields, a tiny signal for Verwey transition appears at 124 K (suggesting the presence of magnetite) although screened by the strong paramagnetic signal of the main components. The SRC has been tested as potential fertilizer on sweet cucumber (Solanum muricatum) which responded positively to the application to carbonatite as an amendment, expressing itself in high foliar biomass.
The main characteristics of photovoltaic (PV) energy and its current development in Latin American and Caribbean countries (LAC); its impact on the electrification of homes, health institutions, and schools in isolated or difficult-to-access communities; and, the advantages thereof are presented and discussed by replacing the use of traditional fuels such as firewood and kerosene in order to improve inhabitants ’health as well as reducing CO2 emissions. Countries like Nicaragua, Peru, Brazil, Argentina, and Chile stand out for their growing PV energy development in the region. A case study of the electrification process by PV systems shows very positive changes are manifested in terms of improving the quality of life of the inhabitants, and especially their physical and mental health state. In addition, CO2 emission reductions from electrifying 216 houses in the nine communities reach an annual amount of 2,164.19 t/yr, reducing firewood consumption by 2,123.39 t/yr and kerosene consumption by 40.80 t/yr However, LAC countries must adopt laws and regulations that regulate the use of PV energy, with an emphasis on recycling systems at the end of their life cycle.
Eco-innovation is the innovation of products that focuses on the use of renewable energy and meets specific environmental requirements, and is essential for energy conservation and environmental protection. There are recommendations and strategies available for general product development, but there are limited studies when focusing on renewable energy products. A proposal for eco-innovation in renewable energy is developed based on exergy analysis, TRIZ methodology, and knowledge management. The model is demonstrated with a specific case study. This study contributes to the analysis and development of products with renewable energy that help mitigate climate change, consistent with the change in the energy matrix. Furthermore, this study is a transdisciplinary effort that integrates concepts from different topics to achieve a comprehensive model.
This article analyzes how smallholders of Subtanjalla, in coastal Peru, conceive irrigation water as a central element and carrier of hydrosocial relations and territories. We base our analysis on an exploration of the local notions of agua nueva and yocle. These two notions bind together time, space, nature and culture into specific understandings of territorial connections and reciprocities. Through these understandings water is much more than H2O. Instead of just representing an economic good or a material input for irrigated agriculture water is seen as a binding element that bridges and brings together the Andean world with that of Subtanjalla in the Peruvian coast. Water is, from this perspective, a lively and always in-the-making composition of humans, non-humans, and more-than-humans in which there is no clear distinction between nature and culture, past and present, object and subject. We argue that water as an assemblage opens up now lines of inquiry into hydrosocial territories and relations across time and space through the departure of a fundamentally relational understandings of water, its use and governance.
The purpose of this research is to have a quantitative analysis on the temperature dependence magnetization of ferromagnetic nanoparticles (NPs), i.e., the Curie temperature (Tc), was systematically studied. The atomistic simulations were carried out using the VAMPIRE 5.0 software based on the Landau-Lifshitz-Gilbert-Heun method. The variable parameters of the simulations were damping, time step, particle geometry (spherical, cubic, and cylindrical) and particle size. We have calculated λ for Fe and Ni, in addition we have found different Tc values for each nanogeometry studied following a finite-size effect. We have found ν values for cubic NPs close to the reported values. In particular, it was observed that the Tc values for the studied geometries in the case of Fe and Ni decreases from their theoretical bulk values, for a critical particle size diameter less than 5 nm. Hence, the presented results (optimized atomistic parameters such as simulation time step, damping, and critical exponents) are the basis for advanced simulations of hybrid and complex nanostructures with perspective in biomedical and environmental applications.
Peptic ulcer is a universal condition that is a public health problem due to its prevalence, risk of complications and socioeconomic impact. This study aimed to determine the antiulcer effect of the hydroalcoholic extract from Senna multiglandulosa leaves against ethanol-induced gastric ulcer in rats. Thirty-six male albino Holtzman rats were assigned to six groups. Group I received physiological saline (PS) at doses of 10 mL/kg; group II: ethanol (PS + ethanol 5 mL/kg); group III; omeprazole 100 mg/kg/day (gold standard); groups IV, V and VI received doses of 100, 250 and 500 mg/kg/day of S. multiglandulosa extract, respectively. The stomach was removed to determine the ulcerative lesions and two sections of the glandular zone to carry out the analysis of the gastric mucus and sulfhydryl groups content. As result, S. multiglandulosa at doses of 250 and 500 mg/kg produced a significant decrease of the injured area, with values of 46.28 ± 7.95 mm2 and 6.91 ± 2.48 mm2, respectively ( P < 0.001 ). The protective effect was showed at dose of 500 mg/kg (92.27%) and a significant increase in the production of mucus with a value of 83.13 ± 13.09 mg/mL/g of tissue (61.14%). The production of nonprotein sulfhydryl groups (NP-SG) also increased significantly at the three evaluated doses, being 250.34 ± 21.16 μg/g tissue at dose of 500 mg/kg (119.94%). It is concluded that S. multiglandulosa extract protected against ethanol-induced gastric ulcer due to increased gastric mucus secretion and its antioxidant activity due to the generation of nonprotein sulfhydryl groups.
Sylvilagus andinus (Thomas, 1897) is a highland lagomorph from the Ecuadorean Paramos. Its distribution was tentatively believed to extend to northwestern Peru on the basis of ecological niche modeling and the inclusion of the Peruvian S. capsalis Thomas, 1913 as a synonym. Here, we confirm the occurrence of S. andinus in Peru by a morphological examination of seven new records from northwestern Peru and one new record from Ancash department in central Peru.
Purpose To assess health-related quality of life (HRQoL) and its associated factors in patients who survived COVID-19 and to assess a prospective evaluation of the prevalence and severity of their depression and anxiety symptoms. Methods We followed up a sample of hospitalized patients who survived COVID-19 at 3 and 12 months after discharge. We assessed HRQoL (Euroqol-5D-5L) through telephone interviews. Any problem in any dimension of Euroqol-5D-5L was considered as low HRQoL. The depression and anxiety symptoms were measured using the Patient Health Questionnaire-9 and Generalized Anxiety Disorder-7 tools, respectively. We estimated the adjusted prevalence ratios (aPR) to low HRQoL using Poisson regression and the changes on their depression and anxiety symptoms during the follow-up. Results We included 119 patients with a mean follow-up time of 363.6 days. 74% of the participants had low HRQoL at one year after hospital discharge and were associated with being ≥ 41 years old (aPR: 1.95), having a previous history of psychiatric diagnoses before COVID-19 infection (aPR: 1.47), having any COVID-19 symptom during the follow-up at one year (aPR: 1.84), and having a family member who had died from COVID-19 during the first wave (aPR: 1.24). In addition, the clinically relevant depression symptoms were frequent, and they increased from 3 (14.3%) to 12 months (18.5%). Conclusion One year after COVID-19 hospitalization discharge, patients had low HRQoL, and their depression symptoms increased. These findings acknowledge the need to provide services that adequately address mental health sequels and HRQoL to reduce the burden of the COVID-19.
The Principles for Responsible Investment in Agriculture and Food Systems (CFS-RAI) are shown as suitable instruments to contribute to the Sustainable Development Goals (SDG) in rural areas. Local Action Groups (LAGs) have proven to be effective governance structures for the implementation and management of rural development projects based on participation and collective action. This research integrates the implementation of the LAG from the CFS-RAI Principles for the design of a rural development strategy. The foundations of these new structures are analyzed and the process of creating a LAG linked to the El Mantaro Regional Development Center (RDC) of the Universidad Nacional Mayor de San Marcos (UNMSM), in the Junín region (Peru), is described. The methodological process incorporates the “Working With People” (WWP) approach and the LEADER (Liaison Entre Actions de Développement de l’Économie Rurale) specificities for the analysis of empirical information obtained in surveys and workshops, with 350 people involved in the process. The results indicate that the LAGs, as multi-stakeholder partnerships linked to the RDC, are a novel way to integrate the CFS-RAI principles from participation, proximity management, strengthening local communities and promoting sustainable development through projects. These results contribute to the empowerment of civil organizations and motivate their participation in local political decisions related to sustainable rural development.
Cadmium (Cd) is a highly toxic heavy metal considered carcinogenic to humans. The adsorption behavior of cadmium adsorption using untreated and chemically modified rice husk was investigated. Experimental tests were carried out to evaluate the influence of the variables pH, initial concentration of cadmium, and dosage of adsorbent in the adsorption process. In optimal experimental conditions, the maximum adsorption efficiency was 92.65%. Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) were used allowing the identification of the main functional groups and morphology of rice husk and treated rice husk, and the results showed an improvement of adsorption characteristics after rice husk treatment with NaOH. The optimum adsorption pH for both types of rice husk was 7. The maximum adsorption capacities of RH and treated RH fitted by the Langmuir model were 5.13 mg/g and 11.06 mg/g, respectively. The pseudosecond order kinetics has the best coefficients of determination for untreated ( R 2 = 0.992 ) and treated ( R 2 = 0.999 ) rice husk. The adsorption process was found to be endothermic in nature with enthalpy of 14.08 kJ/mol and entropy of 170.98 J/mol.K. The calculated activation energy was 24 kJ/mol. The results showed the potential of rice husk as a low-cost, easily managed, and efficient biosorbent for Cd removal from waters.
El presente trabajo estudia las exportaciones peruanas hacia la región de Asia Pacífico (Apac) con estadísticas descriptivas y métodos econométricos enfocados en resolver la cuestión: ¿Las exportaciones peruanas impactan positivamente al crecimiento económico?, y además si la firma de Tratados de Libre Comercio (TLCs) mejora o empeora dicho efecto. Se revisan las exportaciones hacia las subregiones del noreste y sudeste asiático, así como la composición de las exportaciones; además de ese abordaje descriptivo se estiman una serie de modelos de mínimos cuadrados para dar respuesta a la cuestión, en estos se consideran a los países del Apac con los que Perú posee un TLC: China, Japón, Corea del Sur, Tailandia y Singapur. Se emplean variables de control que toman en cuenta los factores de producción (trabajo y capital) y una variable dicotómica del covid. Se encuentra que las exportaciones peruanas constan mayormente de materias primas y se concluye que no hay evidencia de una correlación entre las exportaciones y el PBI, además que los TLCs no afectaron a la relación Exportaciones-PBI, ni al producto bruto interno.
Background: The prognostic value of the neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) in patients with COVID-19 is rarely described in older adults. We aimed to estimate the prognostic value of NLR and PLR, determining the mortality of adults over 60 years of age hospitalized for COVID-19 in three hospitals in Peru from March to May 2020. Methods: We performed a secondary analysis of data from a retrospective cohort carried out in Lambayeque, Peru, from March 18 to May 13, 2020. Older adults hospitalized for COVID-19 were included. The outcome variable was in-hospital mortality by all causes, while the exposure variable was the NLR and PLR (categorized in tertiles and numerically, performing a logarithmic transformation). We included sociodemographic variables, comorbidities, vital functions, laboratory markers, and treatment received during hospital stay. We evaluated the association between NLR and PLR using the hazard ratio (HR) in a Cox regression model. We estimated HR with their respective 95% confidence intervals (95% CI). We estimated cumulative/dynamic time-dependent ROC curves and reported area under the curve ROC (AUC-ROC) for 15-, 30-, and 60-day mortality with their respective simultaneous confidence intervals (confidence bands (CB)). Also, we estimated an optimal cut-off point based on the maximally selected rank statistics. Results: A total of 262 hospitalized older adults were analyzed, 71.8% (n = 188) of whom were male with a median age of 70 years (interquartile range: 65-78). The mean NLR and PLR were 16.8 (95% CI: 14.9-18.7; SD: 15.5) and 50.3 (95% CI: 44.6-55.9; SD: 46.3), respectively. The mortality rate was 68.7% (95% CI: 62.7-74.3). The adjusted Cox regression analysis showed that the high NLR (adjusted HR (aHR) = 2.12; 95% CI: 1.43-3.14) and PLR (aHR = 1.90; 95% CI: 1.30-2.79) tertiles were associated with a higher risk of mortality. The maximum AUC-ROC values at 60 days of follow-up for NLR and PLR were 0.713 (95%CB: 0.627-0.800) and 0.697 (95%CB: 0.583-0.754), respectively. Conclusions: The NLR and PLR are predictors of higher risk of mortality, and these results suggest that both could be reliable and practical markers for the identification of older adults at high risk of mortality by COVID-19. NLR and PLR have prognostic value, with an AUC greater than 0.5; however, by themselves, they are weak prognostic markers. It is important to carry out future studies incorporating these two markers into preexisting models or designing new ones considering them.
Background Fluid therapy plays a critical role in the management of acute pancreatitis. Normal saline (NS) is commonly used in these patients. However, Lactate Ringer’s (LR) has also been shown to be useful for this condition. Aim To assess the effect of LR compared to NS in patients with acute pancreatitis. Methods We searched in three electronic databases from inception to December 2020 for randomized controlled trials (RCTs). Outcomes were mortality, intensive care unit (ICU) admission, hospital stay, and Systemic Inflammatory Response Syndrome (SIRS) at 24, 48, and 72 h. The risk of bias was assessed using the Risk of Bias 2.0 tool. All meta-analyses were performed using a random-effects model. Results Four RCTs comprising 248 patients were included. The mean age ranged from 42.3 to 63.8 years and 49% of patients were men. Patients treated with LR had similar risk of mortality (risk ratio [RR], 0.53; 95% confidence interval [CI], 0.09–3.00) and SIRS at 24 h (RR, 0.69; 95% CI, 0.32–1.51), 48 h (RR, 0.80; 95% CI, 0.46–1.41), and 72 h (RR, 0.68; 95% CI, 0.37–1.25) compared to NS. LR had significantly lower hospital stay (mean difference, − 1.10; 95% CI, − 1.92 to − 0.28) and lower risk of ICU admission (RR, 0.42; 95% CI, 0.20–0.89) compared to NS. The risk of bias was low in nearly all RCTs. Conclusion No differences were found in the mortality and SIRS at 24, 48, and 72 h in patients treated with LR and NS. In contrast, patients who received LR had a lower risk of ICU admission and lower hospital stay than NS.
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14,637 members
Leonardo Romero
  • Facultad de Ciencias Biológicas
Ivonne Bernui
  • Centro de Investigación de Bioquímica y Nutrición "Alberto Guzmán Barrón"
Gustavo A Sandoval
  • Facultad de Ciencias Biológicas
Erasmo Huertas
  • Departamento de Ginecología y Obstetricia
Yesica Llimpe
  • Departamento de Ciencias Dinámicas
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Calle Germán Amézaga 375, Lima 1, Lima, Lima, Peru
Head of institution
Dr. Orestes Cachay Boza
Website
http://www.unmsm.edu.pe
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