bluuebunny/crossref_metadata_2025 huggingface dataset:
Ticking time bomb: implications of the COVID-19 lockdown on e-waste management in developing countries
Authors: Adejumo Oluwadamilola A. , Oluduro Olubisi F.
Published: August 2021

The COVID-19 pandemic has altered the course of events globally since the outbreak of coronavirus disease (COVID-19) in late 2019 giving further credence to the long-standing belief that the world is indeed a global village. There have been different responses by countries to the raging pandemic including the imposition of lockdowns, quarantine and isolation. The imposition of lockdowns, whether full or partial, has not been without major consequences, which has led to information, communication and technological (ICT)-based measures to minimise the effect of the lockdown and as an alternative to physical interactions. The use of ICT devices to bridge the gaps created by the lockdown on schools, businesses and other sectors has led to the increased use of electronic devices. The challenge of electronic waste (e-waste) management in developing countries has been around for a while and the increased use of electronic devices is likely to compound the challenge during and post COVID-19. Whilst the development of ICT-based options as viable alternatives to face-to-face interactions may not be a negative development, this article argues that the existing frameworks are inadequate to manage the resultant increase in e-waste in most developing countries and that there is need now more than ever before for developing countries to exercise caution in embracing these ICT-based options without putting in place measures to ensure that there is increased capacity to manage and dispose of the e-waste created.
Evaluación de las propiedades psicométricas de la Escala de Abuso Online en Relaciones de Noviazgo en adolescentes y adultos jóvenes colombianos
Authors:   Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia, Rey Anacona César Armando , Martínez Gómez Jorge Arturo ,   Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia, Ocampo Rojas Eliana Marcela ,   Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia
Published: August 2021

Introducción/objetivo: Los estudios realizados en algunos países, incluyendo a Colombia, indican altas prevalencias de ciberviolencia en el noviazgo. Sin embargo, en dicho país no se cuenta con instrumentos validados para medir esta forma de violencia. El objetivo de este estudio fue evaluar la confiabilidad y la validez de la Escala de Abuso Online en Relaciones de Noviazgo. Método: Participaron 2023 estudiantes de colegio y universitarios (53% mujeres), entre 13 y 40 años. Resultados: El análisis factorial exploratorio demostró la conveniencia de conservar la estructura original de 20 ítems de las dos escalas del instrumento (perpetración y victimización) y las dos subescalas de cada una (“agresiones directas” y “monitoreo/control”), estructura que fue ratificada por el análisis factorial confirmatorio con índices adecuados de ajuste. Además, las cuatro subescalas correlacionaron significativamente entre sí y con las escalas de la Lista de Chequeo de Experiencias de Maltrato Psicológico en la Pareja. Los índices alfa oscilaron entre .75 y .87. Conclusiones: Estos resultados indican que el instrumento presenta unas propiedades psicométricas que avalan su uso con adolescentes y adultos jóvenes colombianos.
Unsupervised Representation High-Resolution Remote Sensing Image Scene Classification via Contrastive Learning Convolutional Neural Network
Authors: Li Fengpeng , Li Jiabao , Han Wei , Feng Ruyi , Wang Lizhe
Published: August 2021

Inspired by the outstanding achievement of deep learning, supervised deep learning representation methods for high-spatial-resolution remote sensing image scene classification obtained state-of-the-art performance. However, supervised deep learning representation methods need a considerable
amount of labeled data to capture class-specific features, limiting the application of deep learning-based methods while there are a few labeled training samples. An unsupervised deep learning representation, high-resolution remote sensing image scene classification method is proposed in this
work to address this issue. The proposed method, called contrastive learning, narrows the distance between positive views: color channels belonging to the same images widens the gaps between negative view pairs consisting of color channels from different images to obtain class-specific data
representations of the input data without any supervised information. The classifier uses extracted features by the convolutional neural network (CNN)-based feature extractor with labeled information of training data to set space of each category and then, using linear regression, makes predictions
in the testing procedure. Comparing with existing unsupervised deep learning representation high-resolution remote sensing image scene classification methods, contrastive learning CNN achieves state-of-the-art performance on three different scale benchmark data sets: small scale RSSCN7 data
set, midscale aerial image data set, and large-scale NWPU-RESISC45 data set.
Scholars and Literati at the Lubranski College in Poznan (1519–1780)
Authors: De la Croix David
Published: August 2021

This note is a summary description of the set of scholars and literati who taught at the Lubranski College in Poznan, also called Lubranski Academy, from its inception in 1519 to its disappearance in 1780.
Study of the Influence of Clays on the Transfer of Dissolved Oxygen in Water
Authors: Blanco Zúñiga Cesar René , Rojas-Arias Nicolas , Peña Pardo Ludy Yiseth , Mendoza Oliveros Martín Emilio , Martínez Ovalle Segundo Agustín
Published: August 2021

Context: The lack of dissolved oxygen (DO) in water bodies has become a serious problem for several ecosystems due to drastic changes in their climatic, biological, and physical conditions. The presence of microorganisms, organic matter, and clays, which are carried by landslides and rainwater, affect the process of restoration and transfer of DO in water, thus making it necessary to study how these factors affect the process of DO transfer in water bodies.
Method: This work is focused on studying the influence of clays during the DO transfer process in water bodies. To this effect, samples of clays from the region of Paipa, Boyacá, were added in 1, 3 and 5% by weight into the samples of clean water. The aeration process was performed using a constant flow diffusion system. The tests were carried out until the saturation of dissolved oxygen in each of the water samples was obtained.
Results: The results show that the presence of clays during the transfer of DO have little influence on bodies of water. However, variations were observed in time intervals of <5 min in which the increase in the percentage of clays favored the transfer of DO.
Conclusions: With these results, it is concluded that the presence of clays can generate a beneficial effect during the transfer of DO in bodies of water with a high oxygen deficiency, whereas, for water samples with a relatively high percentage of DO, clays can hinder the DO restoration process.
Using the REA Data Model in Order to Reduce Design Complexity in an Inventory Management Relational Database, and the Need for a Relational Database Complexity Metric.
Authors: Adamson Ian
Published: August 2021

With the extensive use of relational databases in the business environment there is a need to reduce database complexity in order to avoid data inconsistency and redundancy, which can provide a company with unreliable and/or meaningless data and information.

The use of the REA Data Model in database design can significantly help with this problem.  The model can eliminate the need for unnecessary data artifacts which should only be generated by the system when needed.

This paper also addresses the need for a Relational Database Complexity Metric. A simple and easy to understand metric is presented.
Do Siblings Reduce Children’s Dietary Quality in China?
Authors: Feng Qundi , He Qinying
Published: August 2021

Using data from the China Health and Nutrition Survey, we examine the effect of the number of siblings on dietary quality with a sample of 2–12-year-old children in China. We use instrumental variables to address the potential endogeneity of the number of siblings. We show that the effect of the number of siblings on children’s dietary quality is significantly negative. Child dietary diversity score will decrease by 0.274 with one more siblings. In terms of children’s nutrition, the intake of fat and protein also significantly decrease. A robustness check using the fixed effects models also validates our findings that child quantity–quality trade-off is apparent in Chinese families.
Anodic protection of 316L stainless steel piping in sulfuric acid service: failure causes and remedial actions
Authors: Bazgir Maryam , Rahmani Khosrow
Published: August 2021

Anodic protection (AP) is one of the corrosion control methods that has been widely used in the manufacture, storage, and transport of sulfuric acid. The present paper gives a brief review of the history, some applications, and a case study of failure causes and remedial actions of AP in a sulfuric manufacturing plant. The AP system consists of a direct current source, cathodes, reference electrodes, and signal conditioning electronics. In a sulfuric manufacturing plant, for AP of 316L piping (as an anode), platinized titanium (Pt/Ti) and Hastelloy B-2 were used as reference and cathode electrodes, respectively. After seven years of operation of the AP system in the sulfuric acid plant, a section of the protected pipelines has severely corroded. The study of the system showed that the reference electrodes, which were titanium-electroplated with platinum, lost their stability in the acid with the loss of coating and caused overprotection. However, the system could not control the pipe’s potential in the AP situation. In this condition, accelerated corrosion of the cathodes and pipes has also occurred.
Potential applications of biogenic selenium nanoparticles in alleviating biotic and abiotic stresses in plants: A comprehensive insight on the mechanistic approach and future perspectives
Authors: Zohra Efat , Ikram Muhammad , Omar Ahmad A. , Hussain Mujahid , Satti Seema Hassan , Raja Naveed Iqbal , Mashwani Zia-Ur-Rehman , Ehsan Maria
Published: August 2021

In the present era, due to the increasing incidence of environmental stresses worldwide, the developmental growth and production of agriculture crops may be restrained. Selenium nanoparticles (SeNPs) have precedence over other nanoparticles because of the significant role of selenium in activating the defense system of plants. In addition to beneficial microorganisms, the use of biogenic SeNPs is known as an environmentally friendly and ecologically biocompatible approach to enhance crop production by alleviating biotic and abiotic stresses. This review provides the latest development in the green synthesis of SeNPs by using the results of plant secondary metabolites in the biogenesis of nanoparticles of different shapes and sizes with unique morphologies. Unfortunately, green synthesized SeNPs failed to achieve significant attention in the agriculture sector. However, research studies were performed to explore the application potential of plant-based SeNPs in alleviating drought, salinity, heavy metal, heat stresses, and bacterial and fungal diseases in plants. This review also explains the mechanistic actions that the biogenic SeNPs acquire to alleviate biotic and abiotic stresses in plants. In this review article, the future research that needs to use plant-mediated SeNPs under the conditions of abiotic and biotic stresses are also highlighted.
Dual model representation of solar photovoltaic cell
Authors: Das Sriparna , Namrata Kumari , Ray Papia
Published: August 2021

The sustainable development of the country is dependent on the utilization of power production from renewable energy sources like solar, wind, hydro, etc. Due to availability of solar energy in most of the places, the focus of using solar energy by implementation of solar PV cells, arrays, panels are the primary strategy. Thus, the designing of solar PV cell is necessary. There are certain topologies i.e. single diode and double diode representation for solar PV cell. But designing these models individually takes utilization of time and resources when implemented in real life scenario. When coming to the performance analysis of these models individually, it is observed that the power production is not in the maximum capability throughout the year. The performance in some months is good for single diode topology whereas in other months double diode topology shows good result. So, a new model is proposed with better performance, combining these two models that will solve the above disadvantages. Further, both the time and price of production goes down as we don’t have to create both the models separately. The entire analysis is studied for an entire year for the place of New Delhi. The comparison is also done taking into consideration of two practically existing solar cells: JAP6-72- 320/4BB and Solarex: MSX60 allowing each model to work as single and double diode representation. As the production capacity of these design is not to its highest extent so, more number of cells are attached in series or parallel fashion to meet the load demand. The proposed design solves this problem and having an error within the limit of 0.31–0.41%. The mathematical modelling is shown followed by designing the model in Simulink and thereafter comparative analysis stating all the disadvantages is analyzed, followed by the solution with the best topology for power production from solar cell. This sequential designing will give clear understanding of the proposed technology.
Aromatase deficiency in an Ontario Old Order Mennonite family
Authors: Kim Sun Young , Colaiacovo Samantha , Dave Sumit , Coughlin Kevin , Langdon Kristen , Stein Robert , Saleh Maha
Published: August 2021

Objectives

Aromatase deficiency is a rare autosomal recessive disease that results in the absence of aromatase. In females it presents with ambiguous genitalia and lack of secondary sexual characteristics during puberty. Aromatase deficiency is not attributed to any specific population, but it is more commonly seen in consanguineous parents. Herein, we report the first Old Order Mennonite family with that diagnosis.

Case presentation

Our proband is an Old Order Mennonite female born with ambiguous genitalia who was identified to carry novel homozygous variant in the CYP19A1 gene c.1304G>A (p. Arg435His). Her older brother was later confirmed with the same genetic diagnosis.

Conclusions

Recognizing the cultural sensitivity, unrecognized affected cases, and late presentation of males affected with aromatase deficiency, this condition may be more prevalent than believed in that population.
External fixation via the anterior inferior iliac spine for proximal femoral fractures in young patients
Authors: Yang Qing , Chen Nong , Fu Wenqin
Published: August 2021

Background and aim

Acute treatment of young patients with proximal femoral fracture (PFF) remains a challenge for trauma surgeons due to major fracture displacement and heavy pain in clinical practice. Traditional methods have a variety of intrinsic defaults and cannot successfully manage the requirements of young patients. Benefiting from our anatomic research, we explored a new method of external fixation for this specific trauma and evaluated its feasibility and clinical outcomes.

Material and methods

Twenty-three young multiple-trauma patients with PFF were included in this study. Surgical treatment was applied using an external fixator via the anterior inferior iliac spine (AIIS). Electronic patient records, surgical characteristics, clinical outcomes, and complications were reviewed for each patient.

Results

The mean surgical time was 30.3 ± 7.3 min. The mean blood loss was 25.3 ± 10.8 mL. No iatrogenic nerve palsy, pin tract infection, failure of external fixation, or bedsores were observed. The postoperative visual analog scale score was significantly lower than the preoperative score (P < 0.01). The mean fracture reduction rate of the femur was 58.1 ± 17.0%, and the mean degree of reduction was 13.5 ± 6.9°. The mean external fixation time was 7.6 ± 4.0 days and intramedullary nailing was performed. The mean hospital, follow-up, and healing times were 28.7 ± 8.7 days, 23.5 ± 7.9 months, and 22.8 ± 5.7 weeks, respectively. The Harris Hip Score indicated excellent or good results in 20 patients.

Conclusion

Collectively, the results of this study revealed that external fixation via the AIIS is a safe, rapid, and effective method for acute treatment of PFF in young patients.
Quasi-decompositions and quasidirect products of Hilbert algebras
Authors: Cīrulis Jānis
Published: August 2021

A quasi-decomposition of a Hilbert algebra A is a pair (C, D) of its subalgebras such that (i) every element a ∈ A is a meet c ∧ d with c ∈ C, d ∈ D, where c and d are compatible (i.e., c → d = c → (c ∧ d)), and (ii) d → c = c (then c is uniquely defined). Quasi-decompositions are intimately related to the so-called triple construction of Hilbert algebras, which we reinterpret as a construction of quasidirect products. We show that it can be viewed as a generalization of the semidirect product construction, that quasidirect products has a certain universal property and that they can be characterised in terms of short exact sequences. We also discuss four classes of Hilbert algebras and give for each of them conditions on a quasi-decomposition of an arbitrary Hilbert algebra A under which A belongs to this class.
New AMS dates for Machu Picchu: results and implications
Authors: Burger Richard L. , Salazar Lucy C. , Nesbitt Jason , Washburn Eden , Fehren-Schmitz Lars
Published: August 2021

Machu Picchu, in Cuzco, is one of the most famous archaeological sites in South America. The precise dating of the monumental complex, however, relies largely on documentary sources. Samples of bone and teeth from individuals buried in caves at four cemeteries around Machu Picchu form the basis for a new programme of AMS radiocarbon-dating. The results show that the site was occupied fromc. AD 1420–1532, with activity beginning two decades earlier than suggested by the textual sources that associate the site with Emperor Pachacuti's rise to power in AD 1438. The new AMS dates—the first large set published for Machu Picchu—therefore have implications for the wider understanding of Inca chronology.
“Real-World” Experience
Authors: Cohen Joel I. , Mark Hailey
Published: August 2021

NGSS guidance indicates that a life science curriculum’s unit on evolution must include the concepts of geologic ages, endangered species, Anthropocene extinction, and biodiversity. Enrichment lessons and labs deepen student understanding of key standards. This lesson enriches students by presenting a real-world opportunity for species conservation. First, instructors ensure a common understanding of background knowledge among students. Second, levels of species endangerment are introduced and students participate in a “willingness to pay” lab involving a philatelic-based fund to protect endangered species. Third, predicted student donation amounts are compared to actual costs needed to conserve and manage species in the wild. Finally, summative reports communicate actual conservation needs by comparing and contrasting two endangered species.
Clinical and Technical Guideline for Endoscopic Ultrasound-Guided Tissue Acquisition of Pancreatic Solid Tumor: Korean Society of Gastrointestinal Endoscopy
Authors: Chung Moon Jae , Park Se Woo , Kim Seong-Hun , Cho Chang Min , Choi Jun-Ho , Choi Eun Kwang , Lee Tae Hoon , Cho Eunae , Lee Jun Kyu , Song Tae Jun , Lee Jae Min , Son Jun Hyuk , Park Jin Suk , Oh Chi Hyuk , Park Dong-Ah , Byeon Jeong-Sik , Lee Soo Teik , Kim Ho Gak , Chun Hoon Jai , Choi Ho Soon , Park Chan Guk , Cho Joo Young
Published: August 2021

Endoscopic ultrasound (EUS)-guided tissue acquisition of pancreatic solid tumor requires a strict recommendation for its proper use in clinical practice because of its technical difficulty and invasiveness. The Korean Society of Gastrointestinal Endoscopy appointed a Task Force to draft clinical practice guidelines for EUS-guided tissue acquisition of pancreatic solid tumor. The strength of recommendation and the level of evidence for each statement were graded according to the Minds Handbook for Clinical Practice Guideline Development 2014. The committee, comprising a development panel of 16 endosonographers and an expert on guideline development methodology, developed 12 evidence-based recommendations in eight categories intended to help physicians make evidence-based clinical judgments with regard to the diagnosis of pancreatic solid tumor. This clinical practice guideline discusses EUS-guided sampling in pancreatic solid tumor and makes recommendations on circumstances that warrant its use, technical issues related to maximizing the diagnostic yield (e.g., needle type, needle diameter, adequate number of needle passes, sample obtaining techniques, and methods of specimen processing), adverse events of EUS-guided tissue acquisition, and learning-related issues. This guideline was reviewed by external experts and suggests best practices recommended based on the evidence available at the time of preparation. This guideline may not be applicable for all clinical situations and should be interpreted in light of specific situations and the availability of resources. It will be revised as necessary to cover progress and changes in technology and evidence from clinical practice.
Pharmachologic Prophylaxis for Post-Endoscopic Retrograde Cholangiopancreatography Pancreatitis
Authors: Choi Jin Ho , Lee Sang Hyub
Published: August 2021

Post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP) is one of the most burdensome adverse events, occurs in about 3 to 15 percent of patients after the procedure. Various and extensive attempts have been made to find proper prophylaxis for PEP. Nowadays, pharmacologic agents consist one of the pivotal axis for prophylaxis for PEP. In this review article, we tried to overview pharmacologic prophylaxis including non-steroidal anti-inflammatory drugs, aggressive hydration, protease inhibitors, exocrine pancreatic secretion inhibitors, and nitrates from recent updated results of randomized controlled studies and key meta-analyses.
Predicting the Severity of Acute Pancreatitis
Authors: Yu Song Yi , Lee Yun Chae , Kim Seong-Hun , Lee Seung Ok
Published: August 2021

Acute pancreatitis has two mortality peaks, which occurs within the first 2 weeks due to organ failure and then weeks or months later as result of multi-organ failure and local complications. Although there have been several clinical and multidisciplinary evaluation measures, imaging tests, and serological tests proposed to forecast severe acute pancreatitis, there is still no single test available to reliably predict the disease severity and time of death. Future large-scale studies are required to develop an assessment scale that can accurately predict the prognosis and mortality risk of severe acute pancreatitis.
Nutrition and Antibiotics for Acute Pancreatitis
Authors: So Hoonsub , Lee Hye Kyung , Song Tae Jun
Published: August 2021

Acute pancreatitis is a sudden inflammatory disease that could be developed into a fatal condition. Traditional dogma was to rest the pancreas by fasting. However, evidence shows the benefits of early enteral feeding resulting in a shorter hospital stay, improved mortality, multi-organ failure, systemic infections, and the need for operative interventions. Clinicians should encourage enteral feeding as soon as possible even in severe acute pancreatitis if there are no contraindications. An immediate solid diet could be attempted. Regarding tube feeding, the nasojejunal tube did not show superiority to the nasogastric tube. Different formulas and probiotics need more investigation. Guidelines are against using prophylactic antibiotics, but Korean centers still report overuse of antibiotics. However, there is still a debate about using prophylactic antibiotics in severe acute pancreatitis. Broad-spectrum antibiotics should be initiated when an infection is suspected. In conclusion, enteral nutritional support and optimal use of antibiotics are the keys to the management of acute pancreatitis.
Selected properties of flat-pressed wood-polymer composites for high humidity conditions
Authors: Borysiuk Piotr , Wikowski Jacek , Krajewski Krzysztof , Auriga Radosław , Skomorucha Adrian , Auriga Alicja
Published: August 2021

This study investigated the possibility of applying flat-pressed wood-polymer composites in conditions of high humidity. The experiment involved three variants of wood-polymer composite panels 16 mm thick, and 680 kg per m3 density. The wood particles were bonded with polyethylene. The share of polyethylene in the core layer was fixed at 50%, while in the face layers the content was varied (40%, 50%, or 60%). The following parameters were examined: modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), screw holding (SH), thickness swelling (TS), water absorption (WA), susceptibility to drilling and milling, wettability and surface free energy, and resistance to mold. The results were compared to particleboard glued with urea-formaldehyde resin. The wood-polymer composite had lower MOR and MOE values and similar IB and SH values. The panels indicated a remarkably higher water resistance (lower TS and WA values) with good surface wettability and high resistance to mold fungi. Additionally, the composites were easier to machine, e.g. drilling or milling, in comparison to standard particleboards.
Bell’s Palsy After Second Dose of Moderna COVID-19 Vaccine: Coincidence or Causation?
Authors: Pothiawala Sohil
Published: August 2021

US Food and Drug Administration (FDA) recommended enhanced safety surveillance to monitor for cases of Bell’s palsy following Moderna vaccine administration in larger populations. The author reports a patient who developed right sided Bell’s palsy 2 weeks after administration of the second dose of Moderna COVID-19 vaccine. Considering this development of symptoms 2 weeks after the second dose of Moderna vaccine administration, there remains a possibility of a causal association. As more people get vaccinated, more information may be available in the future to establish association. Physicians need to maintain enhanced safety surveillance to monitor for cases of Bell’s palsy following mRNA vaccine administration.
Characterization of Cobalt Phthalocyanine Thin Film on Silicon Substrate Using Spectroscopic Ellipsometry
Authors: Al-Adamat K.M. , El-Nasser H.M.
Published: August 2021

The cobalt phthalocyanine film (CoPc) was prepared by an ultra-high vacuum system onto a silicon substrate. Structural features and optical properties of the organic semiconductor CoPc has been determined with the use of spectroscopic ellipsometry over the wavelength interval 300–1000 nm. By restricting it to 900–1000 nm the film thickness is determined, and, by the point-by-point fit, the behavior of the dielectric function is established in the entire spectral region. Thus, the optical properties are determined from spectral ellipsometric data using mathematical models based on Gaussian oscillators, which have led to an excellent fit to the experimental data with a relatively low mean square error. Cobalt phthalocyanine was treated as a uniaxial material.
Configuration Mixing for Po Isotopes within the Interacting Boson Model-2
Authors: Najam L.A. , Abood S.N. , Al-Jomaily F.M.A.
Published: August 2021

We analyze a sequence of 194−204Po isotopes, using the Configuration Mixing (CM) Interacting Boson Model 2 (IBM-2). We set the parameters of Hamiltonian using a least-square fit for the known energy levels, electrical transition rates B(E2), and quadruple moments Q(2+1) for the first excited states. We have a good agreement with the experimental values for all the observables tested, and we infer that the feature of the shape coexistence is concealed in the isotopes of Po, just as in the isotopes of Os and Pt.
Analytic Analysis of Electronic and Transport Properties of Finite Polyenes
Authors: Malysheva L.I.
Published: August 2021

Various important characteristics of finite polyene chains are found on the basis of approximate solutions of the characteristic equations. The obtained approximate and limit expressions for the wave functions, energy gap, etc. can be used for the analysis of the electronic and transport properties of polyenes, which gives a deeper understanding of the fundamental properties of finite alternating polyene chains. We also demonstrate the high efficiency of the proposed approximations as a zero-order estimate for the numerical solution of the characteristic equation.
Surface and Interface Bands of the CdTe–HgTe–CdTe Heterostructure: Evidence of Metallicity
Authors: Yakovkin I.N.
Published: August 2021

Performed full-relativistic DFT calculations have demonstrated that thin HgTe layers are metallic and, with increasing thickness, do not become insulators – either ordinary band insulators or topological insulators. The variations of the potential at the CdTe–HgTe interfaces are found to be negligible in comparison with those at the terminating surfaces of the CdTe–HgTe–CdTe films, so that the interfaces in fact do not form any potential well. It is shown that the interface-related bands of the CdTe–HgTe–CdTe films are situated well below EF, so that a dominant input into the density of states at EF and, therefore, to the conductivity is provided not by the interface states, but by the surface bands of the net layered system. It is reasonable therefore to consider an alternative interpretation of the reported thickness dependence of the conductivity of the system, such as the possible surface segregation of components or unavoidable contaminations, which seems much more realistic than the interpretation based on involving topological insulators and topologically protected surface states.
Un momento estelar de la ingeniería mecánica en Colombia: los diseños de locomotoras de P.C. Dewhurst
Authors: Arias de Greiff Jorge
Published: August 2021

Recuento histórico de los diseños de las locomotoras de vapor de los Ferrocarriles Nacionales.
La relación teoría-práctica, otra faceta de la formación integral
Authors: Sánchez Bolívar Guillermo
Published: August 2021

La enseñanza actual de la ingeniería está caracterizada por la separación entre la teoría y la práctica, el excesivo énfasis en las actividades teóricas, el uso de métodos pedagógicos rígidos y la escasa participación de los estudiantes en investigación y extensión universitaria. Una de las principales estrategias para lograr la formación integral de los estudiantes consiste en estrechar la relación entre la teoría y la práctica, en las diferentes asignaturas y actividades curriculares, mediante el empleo de métodos pedagógicos más adecuados, el fortalecimiento de los vínculos entre la docencia, la investigación y la extensión, y la realización de otras actividades complementarias.
Cálculo simplificado de taludes de excavaciones temporales
Authors: González G. Álvaro J.
Published: August 2021

Se presentan ábacos para evaluación de estabilidad no drenada de taludes temporales de excavación, incluyendo sobrecargas y geometrías arbitrarias. Adicionalmente se incluye la metodología para su desarrollo.
Los rayos: una visión mitológica, científica y tecnológica
Authors: Torres Sánchez Horacio
Published: August 2021

Cuando se me propuso escribir un artículo acerca de la investigación que se ha desarrollado en la Universidad Nacional sobre los rayos en Colombia, para una edición especial de la revista de Ingeniería e Investigación con motivo de los 30 años de la creación del programa de Ingeniería Eléctrica, acepto pensando en recopilar y resumir los diferentes artículos técnicos presentados en varios foros sobre el tema y resultados de la investigación. Sin embargo, considero que para una edición especial era más conveniente referirme a la evolución histórica del conocimiento sobre los rayos, partiendo de lo mitológico, planteando lo científico y mostrando mi visión sobre esta investigación en Colombia.
El nivel tecnológico de la industria metalmecánica plantea nuevos retos a la ingeniería nacional
Authors: Córdoba Nieto Ernesto
Published: August 2021

Se destacan algunos parámetros que revelan el nivel y la potencialidad del arte tecnológico en la Industria Metalmecánica Colombiana. En primer término, la capacidad de innovación es valorada por el soporte de la Ingeniería de Diseño y el nivel de participación de los Ingenieros en el proceso productivo metalmetálico. Por otro lado, descubrir la actual composición y las tendencias de los procesos tecnológicos en la metalmecánica colombiana de transformación, tiene particular significación en la prospectiva de asimilación y desarrollo de las nuevas tecnologías. Finalmente, en el artículo se presenta una apretada síntesis de los aspectos económicos que constituyen el contexto desfavorable por el cual ha debido transitar nuestra Industria nacional en las últimas dos (2) décadas.
Estudio cinético para la oxidación selectiva de etanol a acetaldehído
Authors: Sánchez C. Francisco J. , Carballo S. Luis M.
Published: August 2021

Se explica una metodología para efectuar el Desarrollo del Catalizador. Se hace una revisión bibliográfica, análisis termodinámico, patrones de actividad de catalizadores, pruebas preliminares. Con base en los resultados experimentales se plantea un mecanismo de reacción y una expresión cinética para esta reacción. Se demuestra que bajo las condiciones experimentales ensayadas los efectos de Transferencia de masa y calor, no influyen en la cinética encontrada, por tal razón esta cinética corresponde a la cinética intrínseca.
MARCO DE REFERENCIA
Esta investigación hace parte del programa ALCOHOLQUIMICA del Departamento de Ingeniería Química. Como primer objetivo busca formar un grupo de Investigadores y adquirir conocimiento y destreza en la preparación de catalizadores, estudios cinéticos. Diseño, construcción, simulación y manejo de reactores catalíticos heterogéneos. Como segundo objetivo, el desarrollo de tecnología para la producción de materias primas Químicas actualmente importadas al país, a partir de materias primas disponibles en Colombia. Los materiales para la preparación de los catalizadores y la tecnología desarrollada, han de poder conseguirse e implementarse en nuestro medio.
Current Innovation Sources Driving The Spanish Electric Power Sector
Authors: De Mergelina González-Santander Pablo , Lemus-Aguilar Isaac
Published: August 2021

Renewable energy is not simply the cornerstone of a transition, but an entire electric power revolution. However, which are the technologies with which power companies are going to redesign the electricity industry? Interviews were conducted with innovation managers of the biggest power companies in Spain to shed some light on the innovation sources upon which the electric power system of the future is based. The results revealed that renewable electricity represents a complete paradigm shift. Until now, the system’s net electricity balance has been achieved by adjusting power generation to its demand. However, in a renewable system, electricity generation is limited by and depends on environmental resources, so it cannot be sufficiently controlled to meet the demand at all times. Therefore, it is the electricity consumption that must be adjusted to generation. It was concluded that there are currently nine innovation sources that are redesigning the industry: renewable energy, energy storage systems, electric vehicles, Industry 4.0, smart grids, blockchain, distributed and selfconsumption generation, smart client, and demand side response. Moreover, it was found that system regulations established by governments, business sustainability plans, and open innovation by startups play key roles in the development of innovation.
Verification of a Fabless Device Model Using TCAD Tools: from Bipolar Transistor Formation to I-V Characteristics Extraction
Authors: Barzdenas Vaidotas , Grazulevicius Gediminas , Liobe John , Vasjanov Aleksandr , Kladovscikov Leonid
Published: August 2021

This paper describes the analysis of processes used in microand nanoelectronic device manufacturing. It also presents an exemplary and novel laboratory exercise in which an epitaxial planar n + pn bipolar transistor with junction isolation is illustrated and analyzed stepbystep. Only seven photolithography steps are used to obtain this bipolar transistor structure: for buried layer formation, for junction transistor isolation and collectors regions formation, for base region formation, for emitter and collector n+ region formation, for contact windows, for first aluminum metallization, and, finally, for passivation. Silvaco TCAD software tools are used to implement all of these manufacturing processes and to simulate the resulting IV characteristics of all presented semiconductor structures. This type of laboratory work provides students with basic knowledge and a consistent understanding of bipolar transistor manufacturing, as well as facilitating theoretical understanding, analysis, and simulation of various semiconductor manufacturing processes without the need for costly and lengthy technological manufacturing experiments. This article also presents the conclusions and other benefits of such laboratory work, as well as possible recommendations for further improvement or expansion.
Desempeño innovador y tamaño de la firma: heterogeneidad y sesgo de publicación abordados desde un análisis de meta-regresión
Authors: Bachmann Federico , Liseras Natacha , Graña Fernando Manuel
Published: August 2021

El presente trabajo aborda la relación entre tamaño de la firma y desempeño innovador desde un análisis de meta-regresión (amr). La diversidad de coeficientes de regresión estimados reportados por la literatura empírica lleva a preguntarse si dicha disparidad se debe a la variabilidad muestral o si existen otros factores que moderan esta relación. El amr es una metodología que permite responder esta pregunta y mediante la cual se pueden detectar sesgos en la publicación de resultados de investigaciones empíricas. A partir de una intensa revisión bibliográfica y de la conformación de una muestra de 125 artículos que reportan un total de 880 estimaciones econométricas de la citada relación, se analiza la presencia de heterogeneidad y de sesgo de publicación. Los resultados señalan indicios de sesgos de publicación; una vez descontado dicho sesgo, se observa la persistencia de un efecto positivo del tamaño de la firma sobre el desempeño innovador.
Efecto de las distracciones por el uso del teléfono celular durante la conducción
Authors: Cruz Olver Alexander Tabora
Published: August 2021

La conducción distraída es uno de los factores humanos más importantes en la seguridad del transporte y, por ende, es un riesgo que se está convirtiendo en una creciente preocupación para la seguridad vial. La investigación establece que el uso del teléfono celular puede ser la fuente de distracción más importante para los conductores dentro del vehículo, dado que su uso añade demandas cognitivas, físicas o visuales al conductor hacia una tarea secundaria que desvía la atención de las actividades críticas para una conducción segura y, por tanto, puede afectar negativamente el comportamiento y desempeño del conductor. El objetivo de la presente investigación fue estudiar los efectos de las distracciones debido al uso del teléfono celular en las respuestas del conductor durante la tarea de conducción y su vínculo con la ocurrencia de accidentes de tránsito. Los resultados sugieren que el uso del teléfono celular, independientemente de las tareas y modalidad utilizada tienen un efecto negativo en el comportamiento y desempeño de los conductores y, por tanto, los usuarios que usan el teléfono celular mientras conducen corren un mayor riesgo de estar involucrado en un accidente de tránsito, principalmente los conductores mayores y los jóvenes, siendo estos últimos los que están sujetos a una mayor exposición y altos riesgos ante esta distracción.
Мeat performance of domestic quails after partial feed replacement of wheat with extruded bakery waste
Authors: Lukanov H. , Pavlova I. , Genchev A. , Penkov D. , Peltekov A.
Published: August 2021

The aim of the study was to investigate the effect of the partial replacement of wheat with bakery waste in compound feed on slaughter characteristics, quality and composition of meat in a heavy population of domestic quail. A control group (n = 90), I experimental (n = 90), and II experimental groups (n = 90) quails from meat-producing population WG were formed, respectively fed with basic feed, 5% and 10% replacement of wheat in the feed with extruded baking waste. A slaughter analysis, qualitative and chemical analysis of the meat of male and female representatives of the three experimental groups was performed. The replacement of 5% and 10% of the wheat in the compound feed with extruded bakery waste does not have a negative effect on the slaughter characteristics of the studied quail population. No relationship was observed between the studied physicochemical characteristics of quail meat and the addition of 5% and 10% extruded bakery waste. A similar effect is not observed with regard to the color characteristics of the meat. An exception is the Chroma (C*), where there is a tendency to higher values on the basis of experimental groups. With an increasing proportion of wheat substitution with extruded baking waste, the fat content in breast meat increases (P<0.001). The study leads to the conclusion that the replacement of up to 10% of wheat in the combined feed for quails with extruded bakery waste does not adversely affect the slaughter characteristics, quality, and nutritional value of quail meat.
Characteristics of the onset of puberty in male kids of three breeds
Authors: Stoycheva S. , P. Zunev P. Zunev , Bancheva Ts.
Published: August 2021

The aim of the study was to trace the development of some morphological characteristics of puberty and their development up to the 44th week as well as the relationships between them, to find the best subjects based on the phenotype.
Weaning weight was measured as well as their weight once a month until the 44th week.
Measuring the circumference of the scrotum of experimental young bucks was performed weekly from weaning to 44 weeks of age. Monitoring of the release of the penis from the foreskin was performed weekly from weaning until the time of its full release. The average value of the circumference of the scrotum increased from the 12th week to the 39th week in total for all animals (from 15.8 to 28.4 cm), as well as by breed (BWD - 16.5 to 31 cm ), (Togenburg - 15.5 to 28.5 cm) and (Anglo-Nubian 15.8 to 26.1 cm) (p> 0.05). The variation of the trait was low throughout the study period.
The earliest complete release of the penis in our study was observed in the male kids BWD breed -16 weeks. Togenburg kids reached full release at - 18 weeks. In AN kids, the release was at -24 weeks. The correlation coefficient showed a very strong reliable positive relationship between the studied factors in all three studied breeds. Testicular size and body weight could be used as a determining factor in the selection of prepubertal male kids.
The influence of the sex and height at the withers on pelvis size of donkeys in Austria
Authors: Urošević M. , Drobnjak D. , Vlaeva R. , Dameski P. , Stanišić G.
Published: August 2021

During the recent decades, the donkey, as an ever-employed labour animal, is slowly but steadily losing its value. The agricultural industrialization, mechanization of many processes at the mountain and valley farms led to rejection of the donkeys as a livestock. This reduction in donkey numbers evokes some concerns. This fact is a good reason to study all aspects of these domestic animals, in order to revive their role and to restart their livestock growth in the familiar habitat, and bring them into the new environmental conditions.
For the recent research, 35 donkeys (23 males and 12 females) were chosen. All animals lived on Styria terrain in Austria. The following morphometric parameters were analysed: height at the withers (VG), pelvis length (DK), pelvis width (SK), and point of buttock width (SSK).
For the males, the average height at the withers was 116.70 cm and the average pelvis length – 40.13 cm. The average pelvis width was 38.56 cm, and the average point of buttock width – 16.39 cm.
For the females the average height at the withers was 101.48 cm, the average pelvis length – 36.00 cm, pelvis width was 35.41 cm. The average point of buttock width was 13.66 cm.
These measurements show the influence of the height at the withers on the development of the pelvis, particularly on its width and height for both males and females. Comparatively to other donkey populations of the world, the Austrian donkey has an average size.
Experimental and numerical evaluation of thermodynamic effect on NACA0015 hydrofoil cavitation in hot water
Authors: Le Anh Dinh
Published: August 2021

In this study, the cavitation in hot water, which implies tight interaction of thermodynamic effect, phase change phenomena, and flow behavior, was studied by a combination of experiment and numerical simulation. The experiment in water up to 90°C was performed in the high temperature and high-pressure water tunnel with NACA0015 as a cavitator. The temperature inside the cavity was measured using the high-accuracy thermistor probe. According to the result, the temperature depression in the cavity was increased proportionally with the increase of freestream temperature. The inverse thermodynamic effect was observed with the increase of cavity length when temperature increased. The maximum temperature depression of about 0.41°C was measured in the water at around 90°C. The temperature drop was reasonably captured in simulation by coupling our simplified thermodynamic model with our cavitation model and governing equations. The tendency of temperature depression in the cavity agreed well with experimental data under different flow conditions.
Structure of rings with commutative factor rings for some ideals contained in their centers
Authors: JİN Hai-lan , KİM Nam Kyun , LEE Yang , PIAO Zhelin , ZİEMBOWSKİ Michal
Published: August 2021

This article concerns commutative factor rings for ideals contained in the center. A ring $R$ is called CIFC if $R/I$ is commutative for some proper ideal $I$ of $R$ with $I\subseteq Z(R)$, where $Z(R)$ is the center of $R$. We prove that (i) for a CIFC ring $R$, $W(R)$ contains all nilpotent elements in $R$ (hence Köthe's conjecture holds for $R$) and $R/W(R)$ is a commutative reduced ring; (ii) $R$ is strongly bounded if $R/N_*(R)$ is commutative and $0\neq N_*(R)\subseteq Z(R)$, where $W(R)$ (resp., $N_*(R)$) is the Wedderburn (resp., prime) radical of $R$. We provide plenty of interesting examples that answer the questions raised in relation to the condition that $R/I$ is commutative and $I\subseteq Z(R)$. In addition, we study the structure of rings whose factor rings modulo nonzero proper ideals are commutative; such rings are called FC. We prove that if a non-prime FC ring is noncommutative then it is subdirectly irreducible.