bluuebunny/crossref_metadata_2025 huggingface dataset:
PREVALENCIA DE TRAUMATISMO CRANEOENCEFÁLICO POR ACCIDENTES DE MOTOCICLETAS EM HOSPITALES PÚBLICOS DE LA FRONTERA BRASIL/PARAGUAY
Authors: Insfrán José Luis Gamarra , Cuenca Vivian Fabiola Giménez , Ruiz Cristian Adalberto Zavala , Dias Renato Soares Sanches , Sanchez Cristina José Fernandes , Resende Maikon Oliveira de , Dondoni Tassia , Ferrari Camila Abate , Paula Victor Sato de , Pereira Maria Gabriela Franco
Published: June 2021

Introducción: Los accidentes protagonizados por conductores de motos ocasionan víctimas mortales en un buen porcentaje dentro de los accidentes de tránsito, la lesión cerebral más común en los accidentes ocasionados por motocicletas es el traumatismo craneoencefálico, y se producen en jóvenes entre 15 y 30 años de edad. Objetivo: determinar la prevalencia de traumatismo craneoencefálico por accidentes de motocicletas en los servicios de Urgencia de hospitales públicos de la frontera Brasil/Paraguay. Materiales y métodos: Es un estudio de tipo observacional descriptivo, de corte transversal. fueron evaluados un total de 890 ingresos por accidentes de motocicletas ocurridos en el periodo de junio del 2019 a junio del 2020. Se recolectó información de las historias clínicas correctamente llenadas de los pacientes hospitalizados en el Servicio de Urgencias de los Hospitales. Resultados: Los datos arrojados, demostraron que los individuos que más comúnmente reciben lesiones por TCE son hombres jóvenes en edad productiva; en el lado brasileño de la frontera suceden más casos de accidentes en motocicletas, pero con menor tasa de TCE que del lado paraguayo; en la ciudad de Pedro Juan Caballero, existe un mayor predominio de casos de TCE moderados y graves sobre ciudad de Ponta Porã y en ambas ciudades, es deficiente el registro sobre el uso de casco en motociclistas socorridos en accidentes de tránsito. Conclusiones: Los accidentes en motocicleta en Paraguay y Brasil representan un problema como en muchos otros países del mundo presentando la importancia de mantener políticas públicas que mantengan el rigor de las leyes y la educación del tránsito en dichos países
USO DE LOS PARÁMETROS DE LA ESCALA DE ALVARADO EN PACIENTES PEDIÁTRICOS SOMETIDOS A APENDICECTOMÍA EN UN HOSPITAL PÚBLICO DE PEDRO JUAN CABALLERO-PARAGUAY
Authors: Pitta Ingrid Caldas , Antunes Caroline Aldana , Cargnin Eduarda Gonçalves , Neves Ricardo do Nascimento , Carneiro Murilo Alexandre , Almeida Rafael Domeni , Seles Ana Vitoria Rios , Vieira Ana Carolina Batista , Calvino Helen Cristina de Jesus Porral , Aguiar Sidnei Piero de Oliveira , Gonzalez Mariana Azzolini
Published: June 2021

Introducción: La apendicitis aguda es la causa más común de queja de dolor abdominal, y cuando un abdomen agudo pediátrico resulta en una intervención quirúrgica el principal diagnóstico es de causa apendicular. En los niños siempre se tiende a evitar radiaciones ionizantes y el diagnostico por veces no cuenta con el tiempo de encontrar recursos para estudio. Diversas escalas que incluyen signos y síntomas clásicos más estudios laboratoriales son ampliamente utilizadas en la práctica para diagnóstico. La escala de Alvarado es la más conocida y la que hasta hace unos años mostraba el mejor rendimiento en estudios de validación en la práctica. Objetivo: Presentar la prevalencia de los parámetros de la Escala de Alvarado en pacientes pediátricos sometidos a apendicectomía en un Hospital público de la ciudad de Pedro Juan Caballero Paraguay Materiales y métodos: Estudio de carácter descriptivo, retrospectivo y de corte transversal. La población de estudio fue constituida por 40 pacientes de ambos sexos entre 2 y 18 años de edad, sometidos a apendicectomía. Se recolectaron los datos correspondientes a edad, género, diagnóstico de cirugía, complicaciones y los parámetros de la escala de Alvarado. Resultados: 63% eran niños el 37% eran niña. El grupo etario más frecuente fue el de 7 a 9 años (33%). Las variables más registradas en la escala de Alvarado fueron la migración del dolor en fosa ilíaca derecha (100%) y la presencia de fiebre ≥38º (100%). Las complicaciones registradas fueron más frecuentes en los niños (67%). La mayor cantidad de complicaciones se observó en pacientes de 10 a 12 años (40%). Conclusión: El uso de la escala de Alvarado como regla de predicción y discriminación clínica del riesgo de apendicitis, es reproducible y ofrece ventajas en términos de uso más racional de los recursos y disminución de cirugías innecesarias.
IMPACT OF COVID-19 ON HUMAN HEALTH AND ECONOMY: AN EMPIRICAL STUDY BASED ON THREAT PERCEPTION VARIANCE AMONG SEVERAL DEMOGRAPHIC GROUPS IN INDIA
Authors: Shounak Das  , Rohan Prasad Gupta
Published: June 2021

The entire world is passing through great uncertainty due to the spread of the COVID-19 pandemic. There are, primarily, two major visible threats that the world is facing at this juncture. One is on the health of the masses and other one is on the economy. In Indian context majority of the socio-economic activities are under complete and partial lockdown for several months, since March 25, 2020 and restrictions has been eased in phased manner. This has affected the lives of almost all, especially the poor and marginalized population, agricultural labourers, and the informal sector workforce. India needs to be more proactive and planned when it comes to countering the social and economic effects of any pandemic in future. In this context, it is of equal importance to observe the threat perception prevailing among people belonging to different demographic groups. Threat perception is a serious aftershock of any pandemic that restricts general public in returning to their normal socioeconomic life. It has huge socio-economic back fall. Under this study, the researchers have used survey method to collect primary data on the threat perception of people coming from different demographic groups. The study focus to identify whether there is any variation in threat perception of people regarding COVID-19 pandemic with reference to several demographic groups. To analyze the variation among different demographic groups Kruskal-Wallis Test, popularly known as the H-Test, is used. Henceforth, Post- Hoc Test is also performed to identify the significant differences in threat perception among different pair of sub groups, where demographic factors significantly impact threat perception. The researchers have also conducted Ordinal Logistic Regression to identify the level of variation in dependent variable, explained by independent variables. The variation in threat perception among peoples regarding this disease will definitely have huge impact on their socio-economic lifestyles. The research shows mixed results. The researchers have also suggested some recommendations based on the results of the study to control or rather to bridge up threat perceptional variations regarding COVID-19 for protecting socio-economic backbone of the country.
KEYWORDS: Covid-19, Kruskal-Wallis Test, Lockdown, Ordinal Logistic Regression, Pandemic, Post- Hoc Test, Threat perception.
Competitividad y bienestar en municipios de la Región Sierra en Sonora, México
Authors: Bracamontes Nevárez Joaquín , Camberos Castro Mario
Published: June 2021

La globalización repercute en los procesos productivos e intensifica la competitividad nacional, regional y local; sin embargo, independientemente de la escala en el análisis de la competitividad, la literatura reciente indica que el principal objetivo de ésta debe ser la creación de bienestar. Por ello, en este trabajo el objetivo es analizar si los niveles de competitividad se reflejan en el bienestar de la población regional, para lo cual se estima un índice de competitividad y se utilizan las líneas de bienestar calculadas por el Consejo Nacional de Evaluación de la política Social (Coneval, 2016). Los resultados muestran que la región Sierra, integrada por 38 municipios, registró un índice de competitividad menor que el Estado de Sonora y una mayor proporción de personas cuyo ingreso le era insuficiente para alcanzar su bienestar económico y, de igual manera, la región tenía un mayor porcentaje de personas que no superaban la línea de bienestar mínimo. Esto significa que en la región los niveles de competitividad y el bienestar de población están por debajo de la competitividad y el bienestar del conjunto de la población en el estado de Sonora; sin embargo, lo más importante es mostrar la metodología de análisis utilizada.
Contexto económico y políticas públicas integrales en atención a la niñez en condiciones socio-ambientales de riesgo
Authors: Camarena Gómez Beatriz Olivia , Yañez Quijada Adrian , Valenzuela Quintanar Ana Isabel
Published: June 2021

Un grupo social de prioritaria atención en la agenda política de México es la niñez, sin embargo, tal atención se disipa en el caso de aquella población que vive en contextos de amenaza ambiental y vulnerabilidad social. La compleja red de actores e instituciones involucrados en los procesos de alimentación, educación, ingreso familiar y salud, exige instrumentar políticas integrales que tomen en cuenta los factores estructurales y contextuales que pueden determinar tales procesos. Para evidenciar esa necesidad de instrumentar políticas integrales en atención a la niñez, se realizó un estudio de diseño no experimental de correlación con el fin de mostrar que el vivir en un contexto de precariedad social y amenaza ambiental afecta el neurodesarrollo infantil. Los resultados develaron asociaciones negativas significativas en memoria de trabajo (r= -.396), comprensión verbal (r= -.406) velocidad de procesamiento (r=-.280) y razonamiento perceptual (r= -.437). Se confirma un limitado desarrollo cognitivo en infantes residentes en contextos de amenaza ambiental y precariedad social y, por tanto, la necesidad de impulsar una política de carácter integral que atienda de manera puntual tal problemática.
Distribución comercial de una sopa tradicional con innovación
Authors: Aguilar Quintana David , Velarde Mendívil Alma Teresita , Camarena Gómez Dena María Jesús
Published: June 2021

Los cambios en los estilos de vida de la población, motivados por el desarrollo de los medios de comunicación, la incorporación de la mujer al ámbito laboral, el incremento del comercio mundial, entre otros, han influido en el consumo alimentario de la población y dado pauta al aumento de alimentos pre-cocinados. Entre los productos que ha experimentado un crecimiento, son las sopas listas para consumir. Considerando el potencial de mercado de estos productos, una empresa regional sonorense, generó una sopa lista para consumir donde se combina la tradición y la innovación. El objetivo es identificar la aceptación que tiene en el canal de distribución un alimento tradicional sonorense con innovación como la “Cazuela lista para consumir”, se realizó una investigación mixta de corte transversal, donde mediante la observación y toma de datos en los establecimientos comerciales, se identificó que las recetas que resaltan los elementos emblemáticos de la cocina regional no han llegado a los lineales de las grandes superficies. Existe un potencial de crecimiento para las sopas tradicionales con innovación, no obstante, es necesario enfatizar aspectos de rapidez en la elaboración, los simbolismos asociados a la tradición e identidad, así como un precio competitivo.
Design of a Multi-Functional Wheelchair Based Fuzzy Analytical Hierarchy Process
Authors:   Mechanical Engineering Department, Universitas Riau, Indonesia, Muhammad Nur Iksan Muhammad , Susilawati Anita ,   Mechanical Engineering Department, Universitas Riau, Indones
Published: June 2021

Wheelchairs are tools for humans who experience illness, disabilities, and injuries that cause walking difficulties. There are many types of wheelchairs on the market, while wheelchairs that function to help users defecate flexibly have not been widely sold in the market. Therefore, it is necessary to develop a flexible and multifunctional wheelchair that can assist the users in carrying out their activities. This study aims to develop a design of the multifunctional wheelchair. The designing of multifunctional wheelchair based the FAHP (Fuzzy Analytical Hierarchy Process) method. The use of the FAHP was to select the optimal design and selection of the best alternatives among wheelchair’s indicators of design proposed. The results of calculation of weight values for wheelchair design were obtained a percentage of alternative 1 of 48% and alternative 2 of 52%.
Prevalence and Antibiotic Resistance of Salmonella Species Isolated from Chicken Liver in Peshawar
Authors: Ahmad Gulzar
Published: June 2021

The study was conducted to analyze the prevalence and antibiotic resistance of Salmonella species in chicken liver. For this purpose, a total of 50 chicken liver samples were randomly collected from different areas of Peshawar and examined for the presence of Salmonella. The prevalence rate of Salmonella was 24%. In our study different antibiotics were used against Salmonella, Ofloxacin which is 83.33% susceptible and 16.66% resistant, Cefixime which is 100 % susceptible, Amoxil which is 33.33% susceptible and 66.66% resistant, Azithromycin which is 100% susceptible, Ceftriaxone which is 83.33% susceptible and 16.66% resistant. All the isolates showed the highest resistance to Amoxycillin and the highest sensitive/ susceptible antibiotic was Cefixime followed by Azithromycin. Similarly, Ofloxacin and Ceftriaxone also showed sensitivity against isolated Salmonella spp. Furthermore, it is one of the reasons that human infections of antimicrobial-resistant Salmonella may be due to chicken liver.
Connection Between Indications of Binocular Single Vision Anomalies and Punctum Proximum Among University Students of India
Authors: Mandal Rajib
Published: June 2021

Purpose: To evaluate the connection between indications of binocular single vision anomalies and punctum proximum among university students of India.

Method: This was a cross-sectional prospective study of 90 randomly selected subjects age ranging from18-26 years. The subjects were paramedical students studying in A.J Institute of medical science, Mangalore. After going through a detailed ophthalmic examination including standard binocular vision examination if the subject met the inclusion criteria, according to CISS questionnaire students were divided into two groups (asymptomatic and symptomatic).NPC was measured with RAF rule asking the subject to focus on a single vertical line as a target on the rule. After data collection, data were analyzed in an excel spreadsheet using, paired t-test.

Result: NPC break and recovery value are more in symptomatic (9.479±0.3653 and 10.845±0.4865) subjects than asymptomatic subjects (6.033±1.3966 and 7.598±1.3921), with a highly significant difference between the two groups.

Conclusion: Strong relationship was found between anomalies binocular single vision symptoms and punctum proximum (PP). The assurance of PP is useful to separate the indicative of symptomatic subjects from the asymptomatic. PP was more in symptomatic groups when compared to asymptomatic groups.
On the question of the required foam expansion ratio for sublayer extinguishing of oil and oil products fires in vertical steel tanks
Authors: Молчанов Виктор Павлович , Бастриков Денис Леонидович , Макаров Сергей Александрович , Фещенко Александр Николаевич , Третьяков Алексей Владимирович , Апанасенко Игорь Алексеевич
Published: June 2021

Возможность эффективного тушения резервуаров подслойным способом во многом зависит от подъема пены на поверхность горючей жидкости. Критически рассмотрены существующие методики испытаний высоконапорных пеногенераторов для подслойного пожаротушения. Предложены расчетные формулы для определения величины минимальной кратности пены, способной к подъему, в зависимости от состава и плотности горючей жидкости, высоты столба горючей жидкости, типа используемого пенообразователя. Обоснованы условия применения существующих систем подслойного пожаротушения для резервуаров с различной высотой стенки.

During the certification tests of high-pressure foam generators for sublayer oil and oil products fire extinguishing in the tanks there is created a conditional back pressure at the generator output, and the foam expansion ratio is measured when this back pressure is no longer present. In accordance with the standardized methodology the foam expansion ratio is measured in the measuring container by weight. The derived foam after passing throughout the pipeline is supplied to the measuring container where the foam expansion ratio is measured under the atmospheric pressure. In practice, during fire extinguishing the flammable liquid exerts a constant excess pressure on the formed foam. The expansion ratio of the foam decreases in proportion to the pressure value of the column. As a result, the foam expansion ratio can reduce to a value when the Archimedean buoyant force no longer occurs. In this case, the foam cannot be supplied to the surface of the flammable liquid and the fire cannot be extinguished. The back pressure created at the tank base depends on the height of the tank wall (level of the liquid fuel filling) and on its density. Foam rise is possible if the foam density is lower than the fuel density. Light oil products extinguishing requires greater expansion ratio foam than heavy oil products extinguishing. At the same time, heavy oil products cause greater back pressure and a decrease in the foam expansion ratio. Alcohols in the composition of modern high-octane gasolines produce an additional defoaming effect on the foam, which questions the feasibility of using a sublayer fire extinguishing system of modern high-octane gasolines. The article evaluates a set of parameters that affect the required foam expansion ratio for sublayer extinguishing of oil and oil products fires in tanks and justifies the minimum value of its expansion ratio.
Taking a crack at the dome: histopathology of a pachycephalosaurid (Dinosauria: Ornithischia) frontoparietal dome
Authors: Dyer Aaron D. , LeBlanc Aaron R.H. , Doschak Michael R. , Currie Philip J.
Published: June 2021

Recent studies have identified numerous pathologies in the cranial domes of pachycephalosaurid dinosaurs. These studies utilized CT images of domes to identify secondary woven bone and sclerosis associated with the pathologies. These features were critical for diagnosing post-traumatic osteomyelitis, which supported the head-butting behaviour hypothesis. However, conventional CT image resolution may not be sufficient to identify secondary woven bone or sclerotic bone in fossil specimens. UALVP 8504 (cf. Foraminacephale brevis), a dome possessing putative bone lesions, was thin-sectioned and micro-CT scanned. Thin sections revealed the lesions are lytic, without any secondary woven bone or sclerosis, falsifying the diagnosis of osteomyelitis. The morphology and histology of the lesions of UALVP 8504 are not diagnostic and resemble both post-traumatic and non-traumatic lesions.  However, UALVP 8504 possesses shifted vascular canals (repositioning via remodeling, which maintains anatomical position throughout ontogeny) that are decoupled from growth (), and drifting osteons (secondary osteons where resorption occurs longitudinally and transversely). These demonstrate that the dome has sustained external mechanical loading, likely resulting from an impact or multiple impacts, consistent with the head-butting hypothesis. These impacts may have damaged overlying soft tissues and formed the lesions along the surface. Therefore, we suspect that the pathologies in UALVP 8504 are post-traumatic.
REVISITING THE METHODOLOGICAL DEVELOPMENT IN SOIL EROSION RESEARCH
Authors:   Assistant Professor, Gazole Mahavidyalaya, P.O. Gazole, Malda, West Bengal-732124, INDIA, Sarkar Tanmoy , Pal Tapas ,   Assistant Professor, Raiganj University, Uttar Dinajpur, West Bengal-733134, INDIA
Published: June 2021

Soil erosion (by water) is a major land degradation process that may threat the Sustainable Development Goals (SDG) by its negative impact on environment and human well-being. Soil erosion research demands scientific methods, tools and techniques to assess soil erosion with more accuracy and reliability. Soil erosion research has had experienced crude field-based techniques in early twentieth century to model-based approaches since the 1970s and very recent machine learning and artificial intelligence models to predict soil erosion susceptibility and risk. The paper aims to review the trend in methodological development in soil erosion by water through time. The brief background of different approaches, their relative advantages and disadvantages are reviewed. Depending on the time of establishment and wide application the approaches are classified and represented as erosion plot/runoff approach, erosion pin technique followed by environmental tracer method and model approach in combination with Remote Sensing (RS) and Geographic Information System (GIS). Recent advancement in artificial intelligence and application of statistical techniques have a great potential to contribute in soil erosion research by identifying various degrees of susceptibility in large scale and also to quantify the erosion rate with high accuracy. The Remote sensing (RS) and Geographic Information System (GIS) contribute to develop regional scale data base with exploration of real time data and spatial analysis. The combination of RS & GIS and process-based models must be more effective than the traditional soil erosion model in the context of prediction with greater reliability and validity. The future research on soil erosion is better to focus on the theoretical analysis and development of erosion prediction model with more quantitative refinement and to model the future.
İLYAS KÖYÜNDEKİ (DİYARBAKIR-ÇÜNGÜŞ) TARIM VE HAYVANCILIK İLE İLGİLİ SÖZ VARLIĞI
Authors: TUĞLUK Mehmet Emin
Published: June 2021

Tarihleri boyunca tarım ve hayvancılıkla uğraşan Türkler bunun sonucu olarak daima doğa ile yakın ilişki içinde olmuşlardır. Bu yakın ilişki onların dillerini ve kültürlerini etkilemiş bunun neticesi olarak Türk kültüründe çeşitli sembollerde hayvan figürleri kullanılmış; kişilere, şehirlere ve kullanılan çeşitli aletlere hayvan isimleri verilmiştir. Bazı duygu ve düşünceler hayvanların özellikleri göz önünde bulundurularak adlandırılmış; atasözü, deyim, türkü, masal, ninni ve tekerlemelerde tarım ve hayvancılık ile ilgili birçok kavrama yer verilmiştir. Ağızlarda aynı nesne veya kavramı kullanmak için farklı kelimeler kullanılabilmektedir. Hiç şüphesiz ki dil zenginliğinin göstergesi olan bu durum köyden kente göçün de etkisiyle doğa ve insan arasındaki yakın bağı zayıflatmıştır. Bunun sonucunda kullanıldığı yörenin ağzına yerleşmiş tarım ve hayvancılık adlarıyla ilgili pek çok söz varlığı günümüzde yitirilme tehlikesi ile karşı karşıyadır. Bu çalışmada Diyarbakır’ın Çüngüş ilçesine bağlı İlyas köyünde kullanılan tarım ve hayvancılık ile ilgili söz varlığı tespit edilmiş ve bu söz varlığı yapısal ve işlevsel özelliklerine göre sınıflandırılmıştır.
Green cross-dock based supply chain network design under demand uncertainty using new metaheuristic algorithms
Authors: Hamedirostami Arman , Goli Alireza , Gholipour-Kanani Yousef
Published: June 2021

This study concerns the optimization of green supply chain network design under demand uncertainty. The issue of demand uncertainty has been addressed using a scenario-based analysis approach. The main contribution of this research is to investigate the optimization of cross-dock based supply chain under uncertainty using scenario-based formulation and metaheuristic algorithms. The problem has been formulated as a two-objective mathematical model with the objectives of minimizing the costs and minimizing the environmental impact of the supply chain. Two metaheuristic algorithms, namely non-dominated sorting genetic algorithm II (NSGA-II) and multi-objective invasive weed optimization (MOIWO), have been developed to optimize this mathematical model. This paper focuses on the use of new metaheuristic algorithms such as MOIWO in green supply chain network design, which has received less attention in previous studies. The performance of the two solution methods has been evaluated in terms of three indices, which measure the quality, spacing, and diversification of solutions. Evaluations indicate that the developed MOIWO algorithm produces more Pareto solutions and solutions of higher quality than NSGA-II. A performance test carried out with 31 problem instances of different sizes shows that the two methods perform similarly in terms of the spread of solutions on the Pareto front, but MOIWO provides higher quality solutions than NSGA-II.
Mothers and Non-Mothers in the Labor Market: Mexican Regulations vs. the ILO Maternity Protection Convention, 2000 (No. 183)
Authors:   Universidad Iberoamericana, Mexico City, Mexico, Stępień Barbara
Published: June 2021

This article aims to analyze the social and legal situation of women in the labor market, especially in relation to the impact which maternity status impresses upon this. The author intends to explain why women are discriminated in the labor market (notably once they become mothers) by applying current psychological and economic theories on discrimination. Furthermore, the International and Mexican legal frameworks on the prohibition of discrimination and maternity protection are herein discussed and analyzed. Finally, the author proposes introducing and developing paternity labor rights as a necessary condition to eradicate gender discrimination in the labor market.
La revista Literatura en el sistema literario español de los años 30
Authors: Domingo Martín Javier
Published: June 2021

Literatura (1934) fue una de las numerosas revistas que conformaron el complejo sistema hemerográfico de la denominada Edad de Plata. Dirigida por Ricardo Gullón e Ildefonso Manuel Gil, que venían colaborando juntos desde 1932, con los proyectos de Brújula y Boletín último, se convirtió en una plataforma para los escritores jóvenes que se iniciaban en la literatura a la sombra de los maestros del 27. En este trabajo, que tiene como punto de partida el epistolario inédito de Ricardo Gullón depositado en la Biblioteca Municipal de Astorga, nos proponemos el estudio detallado de la revista a partir del análisis de sus diferentes discursos (identificador, tipográfico, artístico, mercantil, publicitario, social y literario), su producción y consumo en el sistema literario en que se inserta, así como la situación que ocupa en el contexto de las revistas literarias de la II República y los debates teóricos de los años 30.
Kinetics of Copper Ion Leaching from Cement-Solidified Body of Blast Furnace Slag Adsorbing Copper Ion
Authors: Wang Ya Li , Li Zi Mo , Yang Ning , Wei Qi , Hao Li Wei
Published: June 2021

Blast furnace slag has good adsorption performance and can be used to adsorb heavy metal ions in waste liquid. It’s worth studying whether the blast furnace slag absorbing heavy metal ions will pose a potential threat to the environment during the process when used in cement-based materials.This paper has studied the leaching amount of copper ions in the blast furnace slag-cement system was analyzed, and analyzed the leaching kinetics of copper ions. The results showed that the leaching amount of copper ions in the blast furnace slag-cement system that adsorbed copper ions basically met the national standard, and the solidified body age was 28 days,blast furnace slag content 30% is the smallest condition for the amount of copper ion leaching.The leaching model of copper ions in the blast furnace slag-cement system is the Elovich equation, which is a heterogeneous diffusion process. The longer the curing age is the slower the leaching process is completed and do not cause environmental pollution during long-term use.
Effect of Precursor Design on Preparing Open-Cell Aluminum Foam Fabricated by Space-Holder Method
Authors: Wan Tan , Liu Yuan , Xu Fa Ting , Ding Xiang
Published: June 2021

Open-cell aluminum foams with spherical cells have great potential application due to their reliable structural and functional performance. However, a problem of poor cell connectivity always arises during fabrication. Three precursor designs were explored to optimize the cell structure. The results showed that the lack of the treatment of the space holders caused poor cell connectivity and a lower porosity, which could be resolved by introducing alcohol as a binder or hot-pressing space holders in precursor designs. Nevertheless, a poor fluid of the granules in the former had a negative effect on porosity improvement, whereas the latter created a precursor with strong bonding between the granules with good flow characteristics and led to a significant improvement in cell connectivity and porosity. This work could provide an approach to designing precursor structures in order to tailor the structure of the final open-cell aluminum foam.
Hot Compression Deformation Behavior of Spray-Formed AlSn20Cu Alloy
Authors: Li Bao Ying , Zhu Bao Hong
Published: June 2021

The hot deformation behavior of spray-formed AlSn20Cu alloy during hot compression deformation was studied, and the constitutive equation of AlSn20Cu alloy was established. The samples of spray-formed AlSn20Cu alloy were compressed on Gleeble-3500 thermal simulation test machine. The error of the true stress caused by adiabatic heating effect in the experiment was corrected. The constitutive equation of spray-formed AlSn20Cu alloy could be represented by Zener-Hollomon parameter in a hyperbolic sine function. The results showed that the deformation temperatures and strain rates had a notable effect on the true stress of the alloy. At the identical deformation temperature, the true stress increased with the increase of strain rate. When the strain rate was constant, the stress decreased with the increase of deformation temperature. After hot compression deformation, the tin phase was elongated along the direction perpendicular to the compression axis with short strips and blocks. With the increase of deformation temperature and the decrease of strain rate, Sn phase distribution became more homogeneous.
Microstructure Evolution and Mechanical Properties of 67GPa•% Grade Medium Manganese Steel
Authors: Zhang Zhe Rui , Song Ren Bo , Zhou Nai Peng , Huo Wei Feng
Published: June 2021

In this study, a new Fe-6Mn-4Al-0.4C high strength medium manganese hot rolled steel sheet was designed. The influence mechanism of the intercritical annealing (IA) temperature on microstructure evolution and mechanical properties of experimental steel were studied by SEM and XRD. The experimental steel was held for 30 minutes at 640°C, 680°C, 720°C, 760°C, 800°C, respectively. When the annealing temperature was 640°C, cementite particles precipitated between the austenite and ferrite phase boundary. As the annealing temperature increased, the cementite gradually dissolved and disappeared, the fraction of lamellar austenite increased significantly. When the annealing temperature is 800°C, the coarse equiaxed austenite and ferrite appeared. The yield strength (YS) decreased, the product of strength and elongation (PSE) and total elongation (TE) both increased first and then decreased, while the ultimate tensile strength (UTS) showed the opposite trend. The experimental steel exhibited excellent comprehensive mechanical properties after held at 760°C for 30 min. The UTS was 870 MPa, the YS was 703 MPa, and the TE was 77 %, the PSE was 67 GPa·%.
Failure Analysis for Girth Weld of Gathering Pipelines
Authors: Li Fa Gen , Feng Quan , Fu An Qing , Cai Rui
Published: June 2021

Through failure generalization, fracture feature analysis and material performance test, a comprehensively analysis was made on the fracture failure analysis for girth weld of gathering pipelines containing H2S gas. The results showed that the fracture failure might be mainly due to sulfide stress cracking in the girth weld. The crack originated from the fusion line on the inner surface of girth weld and extended along the girth weld to outside closed to bends. The sulfide stress cracking of the girth weld was caused by the intersection of multiple factors. The service condition was located in SSC 3 zone and the SSC risk of girth weld was high. The girth weld itself was not been stress-relieved, and its ability to resist SSC was poor. Due to low wall thickness, welding defects, welding stress and additional load, the actual stress of weld was higher.
Hydrogen Sulfide Stress Cracking in a Q345R Welded Joint
Authors: Han Yan , Luo Jing Bin , Fu An Qing , Yin Cheng Xian
Published: June 2021

In this paper the failure reason of Q345R Welded Joint was studied through macroscopic observation, chemical properties, metallurgical analysis, scanning electron microscope (SEM) and EDS test method. The results showed that there were a large number of micro-cracks in the fracture surface. The reason of cracking is severe banded structure in base metal microstructure, which provided opportunity for hydrogen atoms to enter into the internal of steel when contact with wet hydrogen sulfide environment. The existence of tensile stress promotes the entry of hydrogen atoms and the propagation of cracks. The welding products of this procedure are not suitable for use under sour conditions.
Progress of Laser Cladding Wear Resistant Coating on Titanium Alloy Surface: A Review
Authors: Song Wen Wen , Feng Chun , Zhu Li Juan , Zhang Fang Fang
Published: June 2021

Laser cladding is an effective way to improve the surface hardness and wear resistance of titanium alloy. The powder materials and laser cladding process parameters have great influence on the properties of the wear resistant coating. In order to reduce the common defects including the cracks and pores of the coating, titanium alloy powder and self-melting alloy powder are selected to ensure the good adhesion between titanium alloy and wear resistant coating. In addition, the strengthening phase and self-lubricating phase were added to the laser cladding powder material to improve the micro hardness and reduce the friction coefficient, which bring in the improvement of the wear resistance of the coating. In the present work, the selection principle and application effect of powder materials for wear-resistant coatings are reviewed. the research status of the influence of laser technological parameters on coating properties is discussed. Meanwhile, the methods to reduce the defect of wear resistance coating by laser cladding are proposed.
Oxidation Behavior of LPPS MCrAlY Coatings at High Temperature: Part I TGO Growth and β Phase Depletion
Authors: Zheng Zhao Ran , Yuan Kang
Published: June 2021

MCrAlY can be used as bond coats for thermal barrier coatings (TBCs) with good ductility and excellent resistance against high temperature oxidation and hot corrosion. The behavior of the thermally grown oxide (TGO) scale formed at the MCrAlY coatings plays a key role on the oxidation resistance. In this paper, the oxidation kinetic curves of a MCrAlY coating at 900~1000 °C were obtained by measuring the thickness of the TGO scales. The curves basically conveyed parabolic laws, indicating a diffusion-controlled mechanism of the TGO growth. The thickness of TGO was positively correlated with the consumption of β phase during the early stage of the oxidation processes. After about the half-life of the β phase consumption, the depletion of the β phase significantly accelerated, which was caused by coating-substrate interdiffusion. In addition, the microstructure of the TGO was analyzed
Effect of Heat Treatment on the Microstructure and Mechanical Properties of a Co-Based Superalloy Strip
Authors: Niu Yong Ji , Zhang Yue , Zhang Zhi Wei , An Ning , Gao Yang
Published: June 2021

In this paper, the effect of heat treatment on the microstructure and mechanical properties of a deformed Co-Cr-Ni-W superalloy strip was investigated. The cold-rolled superalloy was annealed at different temperatures 500°C~1240°C for 10min. It was found that hardness increased in the range temperature 500°C~800°C, the annealing had aging strengthening effect, this was due to the fcc~hcp transformation. As the annealing temperature is higher than 800°C, the hardness decreased with the increase of the annealing temperature. There were four inflection points in the influence of annealing temperature on the hardness of the alloy, which were about 800°C,900°C,1050°Cand 1150°C. From 800°C to 900°C, the hardness of the alloy decreased rapidly, recovery and recrystallization was initial. From 900°C to 1050°C, the hardness of the alloy decreased slower, recrystallization was finished and grain growth slowly. The temperature reaches 1050°C to 1150°C, the hardness curve decreased rapidly, carbides dissolution and grain growth was considerable. Above 1150°C, the hardness tended to be stable, the grain growth of the alloy was obvious, and more annealing twins were also formed. As the annealing temperature increased, the tensile strength decreased and the elongation increased. Keywords Cobalt-base superalloy; Heat treatment; Microstructure; Mechanical Properties Yong-Ji Niu,Yue Zhang University of Science and Technology Beijing,Beijing 100083,china; e-mail: niuyongji@163.com Yong-Ji Niu, Zhi-Wei Zhang, Ning An, Yang Gao Beijing Beiye Functional Materials Corproration, Beijing 100192, China
Reasons Analysis on Corrosion Perforation of L245 Pipeline from Interior Wall
Authors: Wu Gang , Zhang Peng , Zhu Li Xia , Luo Jin Heng , Li Li Feng , Rong Ding
Published: June 2021

The leakage accident of corrosion perforation occurred in the L245 oil pipeline. After pipe replacement,the defects were analyzed by means of macro analysis, corrosion product analysis, medium composition analysis, chemical composition analysis, mechanical property test and SEM. The results showed that the corrosion perforation was caused by local corrosion, and the synergistic effect of HCO3- and Cl- in transportation medium was the main cause of local corrosion.
Dynamic Hardness of MCrAlY Abradable Seal Coating
Authors: Guo Dan , Liu Jian Ming , Zhang De Ming , Zhang Xin , Liu Tong
Published: June 2021

The purpose of this investigation is to study the dynamic hardness of MCrAlY abradable coatings under different strain rates. A dynamic indentation device based on the split Hopkinson pressure bar system (SHPB) was used. The results show that the hardness of MCrAlY coating increased with the increase of the strain rate, which has a positive strain rate effect. In addition, the difference of the static hardness of MCrAlY coating prepared by HVOF and LPPS was only 4%, while the difference in dynamic hardness was 16%.
Effect of Graphene Content on the Micromorphology, Microhardness and Micro Frictional Resistance of Co-Ni-Graphene Composite Coating
Authors: Gao Er Long , Wei Guang Ning , Yan Bing Hui , Sun De , Li Xue Song
Published: June 2021

In order to obtain the alloy composite material with high hardness, good anti-friction property and low friction coefficient, the electrodeposition technology was used to prepare nanocrystalline Co-Ni-graphene composite coating on the surface of low carbon steel by means of ultrasonic dispersion combined with mechanical agitation. The influence of graphene content in electrolyte on composite coating was studied. The surface microstructure, composition, phase structure, micro-hardness and micro-wear properties of composite coating were measured by scanning electron microscopy, energy spectrometer, X-ray diffractometer, micro-hardness tester and UNMT-1 comprehensive mechanical testing system for micro-nanometer materials. The results show that with the increase of the content of graphene in the electrolyte the graphene particles were embedded in the alloy coating, which changes the crystal structure of the alloy coating and improves the microhardness and micro friction resistance of the coating. When the content of graphene in the electrolyte was 0.9g/L the microstructure of the composite coating was fine and uniform, the highest microhardness value was 678 HV, the minimum average friction coefficient was 0.15, and the composite coating had good wear resistance.
Anticorrosion Property of TC27 Titanium Alloys and Application Evaluation in Tubing
Authors: Zhang Ye Qin , Qi Li Chun , Huang Yi Sheng
Published: June 2021

In view of the combined effect of the load and the corrosive environment on the downhole tubing and the need for the selection of downhole tubing materials, the study on the pitting corrosion, crevice corrosion, erosion corrosion, high temperature and high pressure simulation of corrosion, galvanic corrosion, resistance to sulfide stress corrosion cracking SSC, resistance to hydrogen induced cracking, stress corrosion cracking test under simulated working conditions for TC27 titanium alloy was carried out. Furthermore, the corrosion performance was evaluated by the test results and evaluation standards such as GB/T 18590-2001, SY/T 7394-2017, GB/T 15748-2013. The results show that TC27 have excellent resistance to pitting corrosion, crevice corrosion and erosion corrosion under the corrosive environment of NaCl and H2S. The alloy also has excellent corrosion resistance and crack resistance under high-intensity environments such as high temperature and high pressure, and has good overall performance, which can effectively meet the needs of anti-corrosion performance of downhole tubing materials in different corrosive environments.
Experimental Investigation on the Heat Dissipation Performance of Bismuth-Based Alloy Thermal Conductive Sheet
Authors: Wang Qian Yu , Cai Chang Li , Deng Zhong Shan
Published: June 2021

At present, the existing thermal interface materials (TIMs) cannot meet the heat dissipation requirements of some high-power density electronic devices. In this study, Bi-based low melting point alloy was made into a thermal conductive sheet to reduce the interface thermal resistance. The thermal conductivity of a thermal conductive sheet was found to be 37.83 W/(m·K), 10 times higher than Dow Corning 5021 thermal grease. In addition, the surface morphology of the Bi-based alloy thermal conductive sheet was changed in this experiment, which was divided into textured and planer type, and the measured interface thermal resistance values lower than Dow Corning 5021 thermal grease by approximately 30% and 27%, respectively. The results prove this Bi-based alloy thermal conductive sheets have the ideal heat dissipation performance and their wide application prospects in high-power density electronic devices.
Design of Transmission Polarization Metasurface Converter
Authors: Han Bo Wen , Li Si Jia , Cao Xiang Yu , Gao Jun
Published: June 2021

The transmission polarization metasurface converter is an effective method to realize the polarization manipulation of the transmission waves, and it is also the research hotspot of metasurfaces. A new broadband transmissive polarization converter was proposed based on the metasurfaces converted incident linearly polarized waves into circularly polarized waves of transmission. The top and bottom layers of the unit were axisymmetric metal patches. The top and bottom layers of metal patches were overlapped and the shape was like an arrow. The thickness of the substrate was 4mm. The polarization conversion mechanism of metasurface was illustrated by parameter optimization and current analysis. The simulation results show that when the metasurface works in the frequency band of 6.71GHz~8.45GHz, the linearly polarized incident wave can be converted into a circularly polarized transmitted wave with axial ratio less than 3dB, and the relative bandwidth can reach 23%. The designed polarization converter has a simple structure and the potential application value in electromagnetic wave control of radio frequency devices.
Optimization of Magnesium Alloy Casting Process: An Integrated Computational Materials Engineering (ICME) Approach
Authors: Chang Xing Yang , Shen Qi , Fan Wen Xue , Hao Hai
Published: June 2021

Traditional casting process optimization usually adopts empirical trial and error method. Process parameters were modified repeatedly within a certain range until a satisfactory solution is obtained, which is costly and inefficient. Therefore, based on integrated computational materials engineering, Magnesium Alloy Simulation Integrated Platform (MASIP) was constructed. MASIP completed the automatic operation of the entire simulation process from the CAD model data input to the process-microstructure-performance. It realized the rapid optimization simulation prediction of process-microstructure-performance, and solved the problems of long cycle and low efficiency of traditional process optimization. This paper studied the low-pressure casting optimization process of magnesium alloy thin-walled cylindrical parts based on MASIP. The calculation took casting temperature, mold temperature and holding pressure as the optimized variables, and the yield strength of the casting as the target variable. The experimental results showed that MASIP can fairly complete the structure simulation and performance prediction of castings, greatly reduce the time cost of the calculation process, and improve the efficiency of process optimization.
Effect of Restored Energy Items in Recrystallization Simulation of AZ31 Magnesium Alloy
Authors: Xiong Jin Lin , Wu Yan , Luo Qiang , Chen Ji Bing , Cheng Wei Dong
Published: June 2021

The effect of restored energy items in recrystallization simulation of AZ31 Mg alloy was studied with multi-order phase field model, and the impact factors during the recrystallization were discussed by changing the parameters of the restored energy item. The simulation results showed that the greater the restored energy, the greater the number of the recrystallized grains.
Microstructure and Mechanical Properties of TiB2/Al-Si Composites Fabricated by Electron Beam Rapid Manufacture
Authors: Yang Qing Feng , Xia Cun Juan , Li Xian Feng , Wang Hao Wei , Liao Nan
Published: June 2021

Bulky sample was fabricated by electron beam rapid manufacture (EBRM) technology, in which Ф1.6 mm wire of in-situ TiB2/Al-Si compositeswas selected as deposition metal, following byT6 heat treatment. The microstructure and mechanical properties of the bulky sample before and afterheat treatment were analyzed. Experimental results showed that the microstructure parallel to the weld was similar to that perpendicular to the weld. The microstructure of the as-deposited sample consisted of columnar and equiaxed grains, in which siliconwas distributed along the grain boundary and the grain size was about 30 μm. Besides, some TiB2 particles converged at the grain boundary. After T6 heat treatment, the average grain size of the sample increasedobviously.The average hardness of the sample was increased to 114.65 HV from 46.55 HV, an increase of 146%. The tensile strength of the sample increased to 326.66MPafrom 143.97 MPa, but the elongationdecreased compared with that of the as-deposited state. The tensile test showed that the mechanical properties of TiB2/Al-Si composites formed by electron beam rapid manufacture were isotropic before and after heat treatment.
Effect of Non-Sulfur Stabilizer on Performance of SBS Modified Bitumen
Authors: Liu Zhao Yang , Mao San Peng , Zheng Gui Tao , Cao Zhi Long , Li Lian , Yu Jian Ying
Published: June 2021

Based on the reason that SBS modified bitumen (SMB) with sulfur stabilizer is easy to degrade during aging, a novel non-sulfur stabilizer, P-benzoquinone oxime (GMF), was used to modify SMB. The effects of GMF and sulfur stabilizer on the thermal storage stability, low-temperature performance and aging resistance of SMB were investigated. The results indicate that GMF is more beneficial to improve the thermal storage stability, the low temperature flexibility and softening point of SMB than that of sulfur. And GMF can restrain the degradation of the low temperature flexibility of SMB after thermal aging as compared with sulfur. Fourier transform infrared spectroscopy indicates that the aging growth index of GMF/SBS modified bitumen is 33.5% lower than that of sulfur/SBS modified bitumen after aging. Fluorescence microscope proves that the addition of GMF can prevent the destruction of cross-linking network structure of SBS in bitumen during aging process, which also demonstrates that GMF can improve the aging resistance of SMB. Therefore, GMF can be more suitable as a stabilizer for SMB.