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  Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
Showing 201 - 265 of 265 Journals sorted alphabetically
Sciential     Open Access  
Scientific African     Open Access  
Scientific American     Full-text available via subscription   (Followers: 510)
Scientific American Mind     Full-text available via subscription   (Followers: 10)
Scientific Bulletin     Open Access   (Followers: 1)
Scientific Data     Open Access   (Followers: 7)
Scientific Journal of Pure and Applied Sciences     Open Access   (Followers: 1)
Scientific Reports     Open Access   (Followers: 83)
Scientonomy : Journal for the Science of Science     Open Access   (Followers: 1)
Selforganizology     Open Access  
Simbiótica     Open Access  
Smart Science     Open Access  
South African Journal of Science     Open Access   (Followers: 2)
South American Sciences     Open Access   (Followers: 2)
South East European University Review (SEEU Review)     Open Access   (Followers: 3)
Springer Science Reviews     Hybrid Journal   (Followers: 2)
Studies in Science Education     Hybrid Journal   (Followers: 18)
Tanzania Journal of Science     Open Access   (Followers: 4)
TD : The Journal for Transdisciplinary Research in Southern Africa     Open Access  
Technologies     Open Access   (Followers: 1)
Temas y Debates     Open Access  
The Innovation     Open Access   (Followers: 8)
The Social Studies     Hybrid Journal   (Followers: 3)
Theoria     Open Access   (Followers: 3)
Transactions of Tianjin University     Full-text available via subscription  
Trilogía     Open Access  
TÜBAV Bilim Dergisi     Open Access  
Türk Bilim ve Mühendislik Dergisi     Open Access  
Uluslararası Bilimsel Araştırmalar Dergisi (IBAD)     Open Access   (Followers: 1)
UNED Research Journal / Cuadernos de Investigación UNED     Open Access   (Followers: 1)
Uni-pluriversidad     Open Access  
Uniciencia     Open Access  
Universitas Scientiarum     Open Access  
Vilnius University Proceedings     Open Access  
Zeitschrift für Didaktik der Naturwissenschaften     Hybrid Journal  
Східно-Європейський журнал передових технологій : Eastern-European Journal of Enterprise Technologies     Open Access   (Followers: 3)

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UNED Research Journal / Cuadernos de Investigación UNED
Number of Followers: 1  

  This is an Open Access Journal Open Access journal
ISSN (Online) 1659-441X
Published by Universidad Estatal a Distancia Homepage  [6 journals]
  • Effect of cutting length on the asexual propagation of tacaco (Sechium
           tacaco; Cucurbitaceae)

    • Authors: José Eladio Monge-Pérez, Karen María Muñoz-López, Michelle Loría-Coto
      Pages: e5238 - e5238
      Abstract: Introduction: There is few information on the vegetative propagation of tacaco (Sechium tacaco). Objective: To evaluate the effect of cutting length on the asexual propagation of tacaco. Methods: We carried out the test in Ujarrás, Cartago, Costa Rica. We use 36 cuttings from secondary shoots, of three different lengths (long, medium and short; 12 cuttings of each length). We treated the cuttings with 10 000ppm IBA, and kept them under greenhouse conditions for 41 days. Then we transplanted them into plastic bags, and kept them under a shade house for 27 days. We evaluated the following variables: root dry weight, aerial part dry weight, aerial part dry weight/root dry weight ratio, change in height, change in number of nodes, change in number of shoots, and change in stem thickness. Results: We did not find significant differences between treatments for any of the evaluated variables. Conclusion: The length of the cutting did not significantly influence the vegetative propagation of tacaco.
      PubDate: 2024-07-17
      DOI: 10.22458/urj.v16i1.5238
      Issue No: Vol. 16 (2024)
       
  • Implementation of a high dose routine dosimetry in a self-shielded
           irradiator

    • Authors: Walter Vargas-Segura, Laura Rojas-Rojas
      Pages: e5229 - e5229
      Abstract: Introduction: Ionizing radiation is applied in various fields, and dosimetric control guarantees the quality and safety of products during the irradiation process. There is a need for dosimetric calibration procedures in industrial irradiation plants, specifically for self-shielded irradiation systems. Objective: To implement high dose dosimetry in the routine control of irradiated materials within a self-shielded irradiator. Methods: We worked with 32 dosimeters; we divided the dose range used into 8 points and used four RED Perspex dosimeters per point. We measured the specific absorbance for each dosimeter; plotted these values against dose and produced a third-degree polynomial fit as a calibration curve. Results: We obtained the calibration curve with an r2 of 0,9997. The uncertainties due to the dispersion of the dosimeters and the calibration curve were 1,39% and 0,22%, respectively, for a total uncertainty of 4,80%. This uncertainty includes dose determination with a factor coverage (k) equal to 2 for a 95% confidence interval. Conclusion: Perspex RED dosimeters can be used for routine control of irradiated products in a self-shielded irradiator system.
      PubDate: 2024-07-01
      DOI: 10.22458/urj.v16i1.5229
      Issue No: Vol. 16 (2024)
       
  • Sprout emission and relationship with climate in pitahaya (Selenicereus
           costaricensis; Cactaceae)

    • Authors: José Eladio Monge-Pérez, Michelle Loría-Coto
      Pages: e5190 - e5190
      Abstract: Introduction: For the production of fruit crops, it is important to know the relationship between climatic variables and crop phenology. There are few studies on this topic in pitahaya cultivation in Costa Rica. Objective: to evaluate the type of relationship between climate and the emission of sprouts in the cultivation of pitahaya cv. San Ignacio. Methods: We carried out the research between 2017 and 2019. We evaluated the following variables: number of vegetative sprouts (NVS), number of reproductive sprouts (NRS), average temperature (Ta), minimum temperature (Tmin), maximum temperature (Tmax), relative humidity (RH), and rainfall (R). We calculated Spearman correlations between variables. Results: We did not find statistically significant correlations between NVS and the other analyzed variables. On the other hand, we observed a significant positive correlation between the NRS and minimum temperature (r=0.52**), rainfall (r=0.36*), and relative humidity (r=0.33*). These results indicate that as precipitation, relative humidity, and minimum temperature increase, the number of reproductive sprouts also increases. We additionally identified correlations between NVS, NRS, and climatic variables during the months prior to sprouting. Conclusion: No defined pattern was observed in the emission of vegetative sprouts, while the emission of reproductive sprouts occurred mainly during the initial and middle phases of the rainy season. Furthermore, it was observed that generally, during the emission of reproductive sprouts, few or no vegetative sprouts were produced.
      PubDate: 2024-07-01
      DOI: 10.22458/urj.v16i1.5190
      Issue No: Vol. 16 (2024)
       
  • Environmental impact and methane emission from the Naranjito garbage dump,
           Guayas – Ecuador

    • Authors: Freddy Gavilánez-Luna, César Morán Castro, Gabriela Campoverde Verdugo
      Pages: e5173 - e5173
      Abstract: Introduction: Outdoor garbage disposal and accumulation sites concentrate water, soil and atmospheric pollution; however, there is little information on this problem in Ecuador. Objective: Assess the environmental impact, including methane emissions, from the open-air garbage dump in Naranjito, Ecuador. Methods: To determine the methane emission rate from solid waste biomass, we applied the static camera method, with a portable device, for 15 continuous days (May-June 2023) and at 08:00, 12:30 and 16:00. For the qualitative evaluation of environmental impact, we used the Global Index weighting, based on the impacts generated in the physical and perceptual environment. Results: The global Index was 53,3, i.e. critical impact; mean emission rate was 858,8mg/m2/h, higher than the emission rate of the surrounding soil (133,4mg/m2/h; p<0,05). Conclusion: A sustainable management alternative is urgent to reduce the methane emission rate in Naranjito.
      PubDate: 2024-07-01
      DOI: 10.22458/urj.v16i1.5173
      Issue No: Vol. 16 (2024)
       
  • Characterization of lactic acid bacteria isolated from two samples of
           biole-type bio-inputs with the production capacity of indolic compounds

    • Authors: Karla Montero-Castro, Jéssica Montero-Zamora, Melissa Chaves Phillips, Cristofer Orozco-Ortiz, Emanuel Araya-Valverde
      Pages: e5160 - e5160
      Abstract: Introduction: Modern agriculture seeks to improve sustainability and reduce environmental impact, while meeting the nutritional needs of current and future generations. A promising strategy is the use of microbial biostimulants to increase crop yields and decrease dependence on agrochemicals and fertilizers. Among these biostimulants, those that use beneficial microorganisms such as plant growth-promoting bacteria stand out. We focused this study on isolating and identifying lactic acid bacteria present in artisanal bioles, and characterizing them by their ability to produce indolic compounds. The findings suggest that some lactic acid bacteria present in the two bioles samples can act as producers of indole compounds, such as 3-indoleacetic acid, which makes them a promising alternative for more sustainable and environmentally friendly agricultural practices. Objective: Isolate and identify lactic acid bacteria present in two samples of artisanal biole, and characterize them by their growth and their ability to produce indolic compounds. Methods: We use molecular techniques such as 16S rRNA gene analysis and multilocus typing sequencing analysis to identify strains of lactic acid bacteria present in artisanal biole. Subsequently, we characterized the isolated strains using growth kinetics and colorimetric tests for the detection of indolic compounds, and the quantification of said compounds using high-efficiency liquid chromatography (HPLC). Results: We identified three different genera of lactic acid bacteria species which were Lacticaseibacillus paracasei, Lactiplantibacillus sp., and Lacticaseibacillus pantheris. Lactiplantibacillus sp. stood out for their ability to produce 3-indoleacetic acid. (M2) and Lacticaseibacillus paracasei (M4) with a concentration of 16,75 µg/mL and 4,57 µg/mL, respectively. Conclusion: Our results suggest that some lactic acid bacteria present in artisanal bioles can act as producers of indolic compounds such as 3-indoleacetic acid, which makes them a promising alternative for more sustainable and environmentally friendly agricultural practices.
      PubDate: 2024-07-01
      DOI: 10.22458/urj.v16i1.5160
      Issue No: Vol. 16 (2024)
       
  • Antibacterial, antifungal, toxic and larvicidal activity of Ficus pumila
           (Moraceae) and Phthirusa stelis (Loranthaceae)

    • Authors: Vilma del Valle Lanza Castillo, Magdielis Sarai Marchán Gómez , Lismary José Rivas Patiño, Willian Celestino Henríquez Guzmán
      Pages: e5008 - e5008
      Abstract: Introduction: Ficus pumila and Phtirusa stelis are emerging as a source of natural products. Objectives: Identify the families of chemical compounds present in the species to be studied. Determine the antibacterial and antifungal activity of the crude extracts of F. pumila and P. stelis. Assess the toxicity of the crude extracts of the species against Artemia sp. Determine effects on Aedes aegypti larvae and. Methods: We evaluated the bioactivity of ethanolic, and isopropyl extracts obtained from the fruits, leaves and stems of both species were evaluated for antibacterial activity, antifungal activity, toxic activity against Artemia sp, A. aegypti larvae and phytochemical study. Results: We identificated flavonoids, tannins, and polyphenols in isopropyl and ethanol extracts of leaves, stems and fruits of F. pumila. We detected flavonoids, tannins, anthraquinones, triterpenes, and polyphenols in isopropyl and ethanol extracts of stems and leaves of P. stelis. We detected flavonoids, tannins, anthraquinones, triterpenes, and polyphenols in isopropyl and ethanol extracts of stems and leaves of P. stelis. F. pumila, the isopropyl stem extract demonstrated the most effective activity, since it exerted antibacterial activity, with inhibition halos being observed on B. subtilis (10 mm) and E. coli (7 mm), while the ethanolic extract of the leaves showed effect on Staphylococcus aureus (11 mm). The ethanolic extract of P. stelis leaves exhibited activity against S. aureus (10 mm), B. subtilis (10 mm) and that of stem extract showed similar results with inhibition zone of halos of 11 and 10 mm, respectively. The isopropyl extract of leaves also displayed activity against E. coli (15 mm). None of the extracts from F. pumila and P. stelis, showed any growth inhibitory effect against the pathogenic fungi. The majority of P. stelis extracts showed positive LC results against Artemia sp., with the ethanolic leaf extract exhibiting high toxicity (0,01 µg/mL). The isopropyl leaf extract also showed high toxicity (0,01 µg/mL), as did the isopropyl stem extract (0,02 µg/mL). The ethanolic and isopropyl extracts of F. pumila and P. stelis did not show toxicity to Aedes aegypti larvae. Conclusion: The plant species F. pumila and P. stelis, can be considered as sources of important and promising compounds for therapeutic research. These plants have shown potential in various studies, and further research could lead to the discovery of new treatments and therapies.
      PubDate: 2024-04-16
      DOI: 10.22458/urj.v16i1.5008
      Issue No: Vol. 16 (2024)
       
  • The role of wild mammals in seed dispersal and food chain in Costa Rican
           coffee agroecosystems

    • Authors: Ronald Sánchez-Brenes, Javier Monge-Meza
      Pages: e5128 - e5128
      Abstract: Introduction: Shade coffee farms are complex ecosystems and there is a need for better understanding of their function and environmental services. Some of their environmental functions are similar to forest ecosystems and biodiversity is important. Mammals play a crucial role in these agroecosystems, controlling vegetation abundance and composition, contributing to seed dispersal, nutrient recycling and soil maintenance through excavation and aeration. Objective: To identify the role of wild mammals in seed dispersal and food chain in Costa Rican coffee agroecosystems. Methods: We worked in Rincón de Mora, San Ramón, Costa Rica, from March 2019 to January 2022. We used Pixestt and Havahart traps, and camera traps, to examine feces and behavior; depending on species, sample size ranged between 2 and 87. Results: We identified 19 species of mammals. Heteromys salvini had coffee beans in its pockets. Echinosciurus variegatoides, Didelphis marsupialis and Philander melanurus fed on the local vegetation. Dasyprocta punctata had the most diet data; we found a beetle in the feces of Procyon lotor and observed Eira barbara chasing D. punctata. Conclusion: Coffee agroecosystems provide food for wild mammals, which in turn contribute to the coffee ecosystem as seed dispersers and population control.
      PubDate: 2024-04-10
      DOI: 10.22458/urj.v16i1.5128
      Issue No: Vol. 16 (2024)
       
  • First pages 16 (Jan-Dec 2024)

    • Authors: UNED Research Journal
      Pages: e5171 - e5171
      PubDate: 2024-02-08
      DOI: 10.22458/urj.v16i1.5171
      Issue No: Vol. 16 (2024)
       
  • Zoonotic and non-zoonotic gastrointestinal parasites in frogs from an
           urban tropical river of Costa Rica

    • Authors: Gabriela Pérez-Gómez, Ana Eugenia Jiménez-Rocha
      Pages: e4803 - e4803
      Abstract: Introduction: The urban ecosystems of Costa Rica are home to several anuran species that coexist with still poorly studied parasites. Objective: To report the presence of zoonotic and non-zoonotic gastrointestinal parasites in Hyalinobatrachium fleischmanni, Espadarana prosoblepon, Smilisca sordida, in urban river habtat in San José, Costa Rica. Methods: We analyzed 30 fecal samples, from specimens kept in the laboratory for ten months, with three diagnostic techniques. Results: We detected for the first time in Costa Rica the presence of Giardia duodenalis and Cryptosporidium parvum in H. fleischmanni, E. prosoblepon and S. sordida (with antigen detection tests); in addition, nematodes (Strongylidae and Rhabdias spp.), intestinal ciliates and cestode eggs with other diagnostic techniques. Conclusion: These urban frogs carried at least six types of parasites, some of them, first reports.
      PubDate: 2023-12-21
      DOI: 10.22458/urj.v16i1.4803
      Issue No: Vol. 16 (2023)
       
  • Electroactive microorganisms in coffee processing wastewater (iron redox
           processes)

    • Authors: Joice Castro Alvarez, Lidieth Uribe Lorío , Paola Fuentes-Schweizer
      Pages: e4806 - e4806
      Abstract: Introduction: Wastewater is often a good source for electrogenic bacteria, which are essential for Microbial Fuel Cells (MFCs). The electrons they release while metabolizing organic matter is evidence of their electrogenic capacity. Objective: To evaluate the iron-reducing capacity of bacteria isolated from coffee wastewater. Methods: We isolated morphologically distinct facultative bacteria from the anode electrode of MFCs, with coffee mill wastewater as our substrate. We did a preliminary identification with the Biolog GEN III system (Biolog Inc. Hayward, CA, USA). To assess the conversion of iron (III) to iron (II) by the isolated bacteria, we tested iron (III) citrate, iron (III) chloride, and iron (III) oxide. For comparison, we used S. oneidensis as a positive control in our experiments. Results: We identified eight bacterial isolates with a predominance of non-sporulated Gram positive bacilli morphology. They have reductive activity of iron compounds, giving the best conversion percentages from a for iron oxide (III). The isolate coinciding with the genus Citrobacter (SB), the only Gram negative bacillus, obtained iron conversion percentages higher than 1,0% in the three iron compounds (maximum: 4,3%). Conclusion: In the residual water from the coffee process, there are bacteria with electrogenic capability that could be used in Microbial Fuel Cells.
      PubDate: 2023-12-21
      DOI: 10.22458/urj.v16i1.4806
      Issue No: Vol. 16 (2023)
       
  • Crustaceans in Phragmatopoma sp. (Polychaeta: Sabellariidae) intertidal
           reefs, Pacific, Costa Rica

    • Authors: José A. Vargas, Rita Vargas-Castillo, Jeffrey A. Sibaja-Cordero
      Pages: e4926 - e4926
      Abstract: Introduction: Annelid polychaete worms of the family Sabellariidae build reefs by cementing together sand grains. These reefs increase local habitat heterogeneity and species diversity. The reefs are used as a refuge by invertebrates, and crustaceans are frequent. Objective: To list the species of crustaceans found in Phragmatopoma sp. reefs on two localities of the North Pacific coast of Costa Rica and at the port of Puntarenas, Gulf of Nicoya estuary. Methods: We dislodged fragments of reef colonies qualitatively at low tide with a chisel, stored them in plastic bags and later disaggregated the fragments by hand. We identified the crustaceans whenever possible and deposited them in the collection at the University of Costa Rica (MZUCR). Results: We identified 30 species: 26 species of macro-crustaceans in samples from the North coast, eight of them Petrolisthes (Porcellanidae). From the Puntarenas samples we identified five species (27 macro-crustaceans and 3 isopods). A few micro-crustaceans (Amphipoda, Isopoda) were also present but not identified. Conclusions: The number of crustacean species found in Phragmatopoma sp. reefs is relatively high but comparisons with other studies are difficult. Porcellanid crabs are common on these reefs. The low diversity of Puntarenas reefs remains unexplained.
      PubDate: 2023-12-08
      DOI: 10.22458/urj.v16i1.4926
      Issue No: Vol. 16 (2023)
       
  • Chemical profile of essential oils of the Costa Rican native tree
           Myrcianthes storkii (Myrtaceae)

    • Authors: Carlos Chaverri, José F. Cicció
      Pages: e4863 - e4863
      Abstract: Introduction: The genus Myrcianthes ranges from southern Florida to Chile, including the Caribbean, and the species Myrcianthes storkii is a shrub or tree found in Costa Rica and western Panama, in wet to very rainy, cloud, and oak forests (altitude 1300-3150m). Objective: To identify the chemical composition of essential oils from leaves, floral buds, and twigs of M. storkii of Costa Rica. Methods: We obtained the essential oils through hydrodistillation in a Clevenger-type apparatus. The chemical composition of the oils was done by GC/FID and GC/MS, using the retention indices on DB-5 and Carbowax types of capillary columns in addition to mass spectra. Results: The oils consisted mainly of terpenoids (55,45-87,75%). A total of 281 compounds accounted for 91,27-74,56% of the total amount of oils. The major constituents from the leaf oil were myrcene (17,44%), cis-calamenene (12,60%), α-pinene (5,48%), (E)-caryophyllene (5,16%), limonene (3,91%), p-cymene (3,71%), 1,8-cineole (2,80%), and α-humulene (2,80%). The floral bud essential oil consisted mainly of α-pinene (15,23%), cis-calamenene (12,70%), myrcene (8,59%), 1,8-cineole (4,26%), germacrene B (3,65%), α-humulene (3,55%), and (E)-caryophyllene oxide (2,93%). The major components of twig oil were cis-calamenene (11,31%), palmitic acid (7,99%), (E)-caryophyllene (4,68%), -cadinene (3,28%), cubenol (3,24%), and (Z)-caryophyllene oxide (2,94%). Conclusion: The presence of a significant quantity of myrcene and cis-calamenene seems to be characteristic of this species.
      PubDate: 2023-12-08
      DOI: 10.22458/urj.v16i1.4863
      Issue No: Vol. 16 (2023)
       
 
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  Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
Showing 201 - 265 of 265 Journals sorted alphabetically
Sciential     Open Access  
Scientific African     Open Access  
Scientific American     Full-text available via subscription   (Followers: 510)
Scientific American Mind     Full-text available via subscription   (Followers: 10)
Scientific Bulletin     Open Access   (Followers: 1)
Scientific Data     Open Access   (Followers: 7)
Scientific Journal of Pure and Applied Sciences     Open Access   (Followers: 1)
Scientific Reports     Open Access   (Followers: 83)
Scientonomy : Journal for the Science of Science     Open Access   (Followers: 1)
Selforganizology     Open Access  
Simbiótica     Open Access  
Smart Science     Open Access  
South African Journal of Science     Open Access   (Followers: 2)
South American Sciences     Open Access   (Followers: 2)
South East European University Review (SEEU Review)     Open Access   (Followers: 3)
Springer Science Reviews     Hybrid Journal   (Followers: 2)
Studies in Science Education     Hybrid Journal   (Followers: 18)
Tanzania Journal of Science     Open Access   (Followers: 4)
TD : The Journal for Transdisciplinary Research in Southern Africa     Open Access  
Technologies     Open Access   (Followers: 1)
Temas y Debates     Open Access  
The Innovation     Open Access   (Followers: 8)
The Social Studies     Hybrid Journal   (Followers: 3)
Theoria     Open Access   (Followers: 3)
Transactions of Tianjin University     Full-text available via subscription  
Trilogía     Open Access  
TÜBAV Bilim Dergisi     Open Access  
Türk Bilim ve Mühendislik Dergisi     Open Access  
Uluslararası Bilimsel Araştırmalar Dergisi (IBAD)     Open Access   (Followers: 1)
UNED Research Journal / Cuadernos de Investigación UNED     Open Access   (Followers: 1)
Uni-pluriversidad     Open Access  
Uniciencia     Open Access  
Universitas Scientiarum     Open Access  
Vilnius University Proceedings     Open Access  
Zeitschrift für Didaktik der Naturwissenschaften     Hybrid Journal  
Східно-Європейський журнал передових технологій : Eastern-European Journal of Enterprise Technologies     Open Access   (Followers: 3)

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