scholarly journals Consumption of Entrained Gases Within Bifilms During a Mg-Alloy Casting Process

2021 ◽  
Author(s):  
Tian Li ◽  
J. M. T. Davies ◽  
Dan Luo
Keyword(s):  
Oxide Film ◽  
Layered Structure ◽  
Solid Phase ◽  
Oxide Films ◽  
Casting Process ◽  
Mg Alloy ◽  
Surface Films ◽  
Alloy Casting ◽  
Negative Effect

AbstractThe formation of entrainment defects, (also known as double oxide film defects or bifilms), caused by the entrapment of a doubled-over surface oxide film containing a small amount of local atmosphere, has been investigated by combining practical experiments using a commercial-purity Mg-alloy under protective gases, with theoretical thermodynamic calculations. Evolution of the entrainment defects was studied, and a double-layered structure of their oxide films was found, which was different from the single-layered structure of the Mg-alloy melt surface films that have been previously reported. A pore gas analyzer was used to analyze the gas trapped within the defects from which H2 and N2 (from the air) were detected. It was found that entrapped gases can be depleted through reactions with the surrounding liquid Mg-alloy, resulting in the oxide films growing together in the melt. Transformation of the entrained gas to solid-phase compounds could reduce the void volume of the defects, thus probably diminishing the negative effect of the entrainment defects on the quality of castings.

Effect of Type and Concentration of Aqueous Solutions on Corrosion Behaviour of Plasma Electrolytic Oxide Films on ZM21 Mg Alloy

2019 ◽  
Vol 969 ◽  
pp. 309-314
Author(s):  
V. Ram Kumar ◽  
V. Muthupandi ◽  
K. Sivaprasad
Keyword(s):  
Oxide Film ◽  
Aqueous Solutions ◽  
Corrosion Behaviour ◽  
Oxide Films ◽  
Mg Alloy ◽  
Oxide Ceramic ◽  
Test Results ◽  
Electrolytic Oxidation ◽  
Thickness Meter ◽  
Plasma Electrolytic

Plasma electrolytic oxidation (PEO) is a technique employed to significantly enhance the corrosion and tribological properties of the materials by forming an oxide ceramic film on the surface of the material. In this investigation, ZM21 Mg alloy was subjected to PEO treatment in silicate and phosphate-based aqueous solutions of 5grams and 10 grams per liter concentrations. The oxide film was characterized using SEM, profilometer, thickness meter, and polarization test. Results showed that the oxide film obtained with 10g/L phosphate-based solution offers higher corrosion resistance than the oxide films formed with other solutions.

Computational and experimental study of lattice structured patterns for casting process

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ablyaz Timur Rizovich ◽  
Muratov Karim Ravilevich ◽  
Алексей Aleksey Шумков ◽  
Evgeniy Shlykov ◽  
Sahil Dhiman ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Dimensional Accuracy ◽  
Casting Process ◽  
Content Type ◽  
Cell Parameters ◽  
Alloy Casting ◽  
Ni Alloy ◽  
Porosity Coefficient ◽  
Ceramic Shell Mold

Purpose The quality of lost foam casted engineering components is directly influenced by the characteristics of the respective ceramic shell mold (CSM) and hence casting pattern. In this present work, rapid prototyping (RP) was used to fabricate the lattice structured patterns (LSPs) to reduce the defects and cracks in CSM during the heating stage. Design/methodology/approach The quality of the LSPs was accessed by measuring the dimensional accuracy. Further, the thermal stress in the CSM during the heating of porosity varied LSPs was analyzed using ANSYS software package 16.0. The Ni-alloy casting was fabricated by using the designed LSP and compared with its respective CAD model to access its quality. Findings The obtained results revealed that the Wigner–Seitz LSPs retained high accuracy and minimized the stress for defect-free CSM. Also, the thermal stress generated in the CSM depends upon the porosity coefficient of the LSP. Hence the interplay with porosity coefficient of LSPs leads to the formation of defect free CSM and hence high quality casting. Originality/value RP was used to develop LSPs and investigated the dependency of unit cell parameters on the accuracy of the final casting.

Vocation Education Quality from Demand Side’s Perspective: The Case of Transport Technology Universities in the North of Vietnam

2019 ◽  
Vol 10 (11) ◽  
pp. 1089-1097
Author(s):  
Nguyen Quynh Hoa ◽  
◽  
Phung Chu Hoang ◽  
Keyword(s):  
Vocational Training ◽  
Vocational Education And Training ◽  
Quality Outcomes ◽  
The North ◽  
Job Opportunities ◽  
Management Capacity ◽  
Negative Effect ◽  
Training Quality ◽  
And Training

Quality outcomes from vocational education and training (VET) are fundamental to ensuring a skilled workforce and supporting a productive economy. The quality of vocational training from the demand’s perspective is defined as meeting the customer specification, needs or requirements. Using the method of Exploratory Factor Analysis (EFA) and Multiple Regression Analysis to get the analytical results of 275 respondents as graduates of University of Transport and Communication, University of Transport Technology (the two universities training on transportation in the North of Vietnam), the results show that factors are measured by the observed variables in the study that ensure reliability and relevance. The descriptive statistics result of vocational training quality is 3.28, while all independent variables are at average level (between 3.1 to 3.48) with the highest value related to the quality of the teacher and the lowest are facilities and training programs and management capacity of university. However, the regression results show that the qualification of the teacher, material facilities and training program, management capacity and job opportunities at the training school do not affect the quality of the training while “Learners-NH” have a great positive effect and the labor market information has a negative effect on the training quality of the school significantly. Base on those data, some policy recommendations have been given out in order to improve the training quality of transport technology universities in the north of Vietnam in particular and the vocational training quality of Vietnam in general.

The Impact of Competitive Quasi-Market on Service Delivery in Benue State University, Makurdi Nigeria

GIS Business ◽  
2019 ◽  
Vol 14 (4) ◽  
pp. 85-98
Author(s):  
Idoko Peter
Keyword(s):  
Service Delivery ◽  
A Priori ◽  
Least Square ◽  
Secondary Source ◽  
State University ◽  
Ordinary Least Square ◽  
Negative Effect ◽  
The Impact ◽  
The Relationship

This research the impact of competitive quasi market on service delivery in Benue State University, Makurdi Nigeria. Both primary and secondary source of data and information were used for the study and questionnaire was used to extract information from the purposively selected respondents. The population for this study is one hundred and seventy three (173) administrative staff of Benue State University selected at random. The statistical tools employed was the classical ordinary least square (OLS) and the probability value of the estimates was used to tests hypotheses of the study. The result of the study indicates that a positive relationship exist between Competitive quasi marketing in Benue State University, Makurdi Nigeria (CQM) and Transparency in the service delivery (TRSP) and the relationship is statistically significant (p<0.05). Competitive quasi marketing (CQM) has a negative effect on Observe Competence in Benue State University, Makurdi Nigeria (OBCP) and the relationship is not statistically significant (p>0.05). Competitive quasi marketing (CQM) has a positive effect on Innovation in Benue State University, Makurdi Nigeria (INVO) and the relationship is statistically significant (p<0.05) and in line with a priori expectation. This means that a unit increases in Competitive quasi marketing (CQM) will result to a corresponding increase in innovation in Benue State University, Makurdi Nigeria (INVO) by a margin of 22.5%. It was concluded that government monopoly in the provision of certain types of services has greatly affected the quality of service experience in the institution. It was recommended among others that the stakeholders in the market has to be transparent so that the system will be productive to serve the society effectively

INFLUENCE OF DICARBOXYLIC ACIDS ON SOWING QUALITY OF SPRING BARLEY

1970 ◽  
pp. 22-25
Author(s):  
N. N. Loy ◽  
S. N. Gulina
Keyword(s):  
Organic Acids ◽  
Spring Barley ◽  
Dose Range ◽  
Dicarboxylic Acids ◽  
Rotary Machine ◽  
Working Solution ◽  
Negative Effect ◽  
Sprouted Seeds

The effect of presowing seed treatment on various concentrations of dicarboxylic (organic) acids on the sowing characteristics of spring barley has been studied. Seeds were treated with organic acids obtained by exposing cuttings to the radiation with a dose of 100 kGy and consequent hydrolysis, in concentrations: 1•10-7 %; 1•10-9; 1•10-11; 1•10-13 and 1•10-15 % on a laboratory rotary machine RVO-64 for one day before laying for germination. Distilled water was used for the control case. The rate of application of the working solution calculated as 10 liters / ton of seeds. Seeds were germinated in filter paper rolls in accordance with GOST 12038-84 requirements. The temperature was maintained at +24 ° C in the thermostat where the glasses with rolls were placed. For determination of germinative power and laboratory germination the sprouted seeds were evaluated after three and seven days, respectively. In laboratory experiments it was established that the treatment of barley seeds of varieties Zazersky 85, Nur and Vladimir with organic acids (OK) in different concentrations had both a stimulating and a negative effect. On the Zazersky 85 variety, in variants with acid concentrations of 1•10-9 and 1•10-11, an increase in germination energy (EP) by 2-4% and a significant decrease (by 3-4%) of laboratory germination (LV) of barley seeds were noted. On the Nur variety, the increase in EP was observed at 4% (concentration 1•10-11), LV and seed growth force (CPC) by 2-7% at a concentration of 1•10-7 and in the dose range 1•10-11 - 1•10-14 compared to the control values. On the grade of Vladimir, an increase in EP, LV, and CPC was found to increase by 1-6% at concentrations OK 1•10-7 and 1•10-13. It was shown that the treatment of seeds with acids led to an increase in the length of the germ in all studied varieties (by 3-9%) and dry biomass of 7-day-old seedlings - by 3-6%. Consequently, the treatment of seeds with a mixture of dicarboxylic acids has a stimulating effect on the sowing quality of spring barley.

Beech sapling architecture following small and medium gap disturbances in silver fir-beech old-growth forests in Slovenia

2005 ◽  
Vol 156 (12) ◽  
pp. 481-486 ◽  
Author(s):  
Jurij Diaci ◽  
Lahorka Kozjek
Keyword(s):  
Light Intensity ◽  
Quality Characteristics ◽  
Stem Length ◽  
Silver Fir ◽  
Beech Forests ◽  
Vertical Growth ◽  
Relative Light Intensity ◽  
Stem Bending ◽  
Negative Effect

The objective of our research was to examine the effect of canopy shading on beech sapling architecture in the oldgrowth silver fir-beech forests of Pecka and Rajhenavski Rog. In August 2003 we sampled one plot (352 m2) in a large gap in Pecka, which was a result of a strong windstorm in 1983, and eight small gaps (26–78 m2) with similar sapling heights (3.8–8 m). A ground view of each gap was drawn including the characteristics of gap border trees and the density of separate sapling layers was recorded. The height and diameter were measured for each sapling, as well as the following quality characteristics on selected dominant saplings: width of the crown,number of larger branches and knots (&gt;1/3 DBH), intensity of stem bending, deviation from vertical growth, number of terminal shoots, and the type of damage. The results show a negative effect of high canopy shading (estimated relative light intensity was below 5%) on the architectural quality of saplings. A lower overall density of saplings, greater intensity of bending and deviation from vertical growth, a shorter stem length without branches, a larger number of saplings with two terminal shoots, and a larger number of damaged saplings were observed in small gaps.

Relevant Factors in Increasing School Principals' Entrepreneurship for Improving Students 'Achievements

2020 ◽  
Vol 11 (1) ◽  
pp. 75-75
Author(s):  
Bambang Ismanto ◽  
Lasmono Tri Sunaryanto ◽  
Gatot Sasongko
Keyword(s):  
Path Analysis ◽  
Learning Methods ◽  
Creative Behavior ◽  
Central Java ◽  
Negative Effect ◽  
Rank And Tenure ◽  
Use Of Social Media ◽  
Improving Student Achievement ◽  
Positive Effect

Entrepreneurship of principals in the educational environment to enhance students' creative behavior and achievements through innovation and the development of learning methods is very important. The principal has the task of managing resources and taking advantage of opportunities in improving the quality of education. This study aims to discuss the significant variables in increasing entrepreneurship principals. The study uses a quantitative approach with path analysis. The research sample was 334 Principals of Kindergarten, Elementary, Middle and High Schools in Central Java Province. Data collection was carried out by studying documentation and questionnaires. Data analysis was performed by path analysis with the AMOS program. The results showed that the rank and tenure as a teacher had a positive and significant effect on the tenure as a principal. While the use of social media has a significant negative effect. Of the various independent variables observed, only the existence of opportunities that had a significant positive effect on the ability of innovation of the principal. While the variables that significantly influence the development of learning methods are the ability of innovation and the presence of opportunities. The development of learning methods and the existence of opportunities will subsequently have a positive effect on improving student achievement, as the ultimate goal of developing entrepreneurship by the principal. Pathways to improve the entrepreneurship of principals are the existence of opportunities, tenure as principal, innovation and the development of instructional media. Keywords: Entrepreneurship, Principal, Inovation. Creativity,

ВЛИЯНИЕ ТВЕРДОФАЗНОЙ РЕКРИСТАЛЛИЗАЦИИ С ДВОЙНОЙ ИМПЛАНТАЦИЕЙ НА ПЛОТНОСТЬ СТРУКТУРНЫХ ДЕФЕКТОВ В УЛЬТРАТОНКИХ СЛОЯХ КРЕМНИЯ НА САПФИРЕ

2020 ◽  
Vol 96 (3s) ◽  
pp. 154-159
Author(s):  
Н.Н. Егоров ◽  
С.А. Голубков ◽  
С.Д. Федотов ◽  
В.Н. Стаценко ◽  
А.А. Романов ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Solid Phase ◽  
Modern Method ◽  
Structural Defects ◽  
Structural Quality ◽  
Mos Transistors ◽  
Ultrathin Layers ◽  
Heteroepitaxial Layers ◽  
Xrd And Tem

Высокая плотность структурных дефектов является основной проблемой при изготовлении электроники на гетероструктурах «кремний на сапфире» (КНС). Современный метод получения ультратонких структур КНС с помощью твердофазной эпитаксиальной рекристаллизации позволяет значительно снизить дефектность в гетероэпитаксиальном слое КНС. В данной работе ультратонкие (100 нм) слои КНС были получены путем рекристаллизации и утонения субмикронных (300 нм) слоев кремния на сапфире, обладающих различным структурным качеством. Плотность структурных дефектов в слоях КНС оценивалась с помощью рентгеноструктурного анализа и просвечивающей электронной микроскопии. Кривые качания от дифракционного отражения Si(400), полученные в ω-геометрии, продемонстрировали максимальную ширину на полувысоте пика не более 0,19-0,20° для ультратонких слоев КНС толщиной 100 нм. Формирование структурно совершенного субмикронного слоя КНС 300 нм на этапе газофазной эпитаксии обеспечивает существенное уменьшение плотности дислокаций в ультратонком кремнии на сапфире до значений ~1 • 104 см-1. Тестовые n-канальные МОП-транзисторы на ультратонких структурах КНС характеризовались подвижностью носителей в канале 725 см2 Вс-1. The high density of structural defects is the main problem on the way to the production of electronics on silicon-on-sapphire (SOS) heteroepitaxial wafers. The modern method of obtaining ultrathin SOS wafers is solid-phase epitaxial recrystallization which can significantly reduce the density of defects in the SOS heteroepitaxial layers. In the current work, ultrathin (100 nm) SOS layers were obtained by recrystallization and thinning of submicron (300 nm) SOS layers, which have various structural quality. The density of structural defects in the layers was estimated by using XRD and TEM. Full width at half maximum of rocking curves (ω-geometry) was no more than 0.19-0.20° for 100 nm ultra-thin SOS layers. The structural quality of 300 nm submicron SOS layers, which were obtained by CVD, depends on dislocation density in 100 nm ultrathin layers. The dislocation density in ultrathin SOS layers was reduced by ~1 • 104 cm-1 due to the utilization of the submicron SOS with good crystal quality. Test n-channel MOS transistors based on ultra-thin SOS wafers were characterized by electron mobility in the channel 725 cm2 V-1 s-1.

scholarly journals Long-Term Cryopreservation Does Not Affect Quality of Peripheral Blood Stem Cell Grafts: A Comparative Study of Native, Short-Term and Long-Term Cryopreserved Haematopoietic Stem Cells

2021 ◽  
Vol 30 ◽  
pp. 096368972110360
Author(s):  
Daniel Lysak ◽  
Michaela Brychtová ◽  
Martin Leba ◽  
Miroslava Čedíková ◽  
Daniel Georgiev ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Statistical Significance ◽  
Extended Period ◽  
High Dose ◽  
Atp Production ◽  
Cd34 Cells ◽  
Negative Effect

Cryopreserved haematopoietic progenitor cells are used to restore autologous haematopoiesis after high dose chemotherapy. Although the cells are routinely stored for a long period, concerns remain about the maximum storage time and the possible negative effect of storage on their potency. We evaluated the effect of cryopreservation on the quality of peripheral stem cell grafts stored for a short (3 months) and a long (10 years) period and we compared it to native products.The viability of CD34+ cells remained unaffected during storage, the apoptotic cells were represented up to 10% and did not differ between groups. The clonogenic activity measured by ATP production has decreased with the length of storage (ATP/cell 1.28 nM in native vs. 0.63 in long term stored products, P < 0.05). Only borderline changes without statistical significance were detected when examining mitochondrial and aldehyde dehydrogenase metabolic activity and intracellular pH, showing their good preservation during cell storage. Our experience demonstrates that cryostorage has no major negative effect on stem cell quality and potency, and therefore autologous stem cells can be stored safely for an extended period of at least 10 years. On the other hand, long term storage for 10 years and longer may lead to mild reduction of clonogenic capacity. When a sufficient dose of stem cells is infused, these changes will not have a clinical impact. However, in products stored beyond 10 years, especially when a low number of CD34+ cells is available, the quality of stem cell graft should be verified before infusion using the appropriate potency assays.

scholarly journals Enhancing the Quality of Two Species of Baby Leaves Sprayed with Moringa Leaf Extract as Biostimulant

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1399
Author(s):  
Stefania Toscano ◽  
Antonio Ferrante ◽  
Ferdinando Branca ◽  
Daniela Romano
Keyword(s):  
Leaf Extract ◽  
Foliar Application ◽  
Sugar Content ◽  
Nitrate Content ◽  
Specific Response ◽  
Yield And Quality ◽  
Negative Effect ◽  
Species Specific ◽  
Moringa Oleifera Lam

Natural biostimulants obtained by plants are intensively used nowadays to improve crop yield and quality. The current study aimed to evaluate the effects of leaf extract of moringa (Moringa oleifera Lam.) (MLE) in modifying baby leaf characteristics of two genotypes of Brassica. The trial was started in October 2020 in a greenhouse; a cultivar of kale ‘Cavolo Laciniato Nero di Toscana’ (CL) and a Sicilian landrace of sprouting broccoli ‘Broccoli Nero’ (BN) were used. The plants, after 15, 30 and 40 days from sowing, were treated with MLE, while the control plants (C) with distilled water. Treatment with MLE modified morphological and nutritional value, but with different behavior in the two genotypes. In fact, in BN the treatment reduced the antioxidant activity (2.2-diphenyl-1-picrylhydrazyl (DPPH)) by 54%, while in CL the treatment increased this parameter by 40%. For the phenolic concentration and the sugar content the values recorded were significantly increased by MLE compared to control plants in CL, where in BN a significant reduction was registered. The CL plants treated with MLE showed a significant reduction (−70%) in nitrate content compared to the control plants; a negative effect was, instead, observed in BN, where the plants treated with moringa showed an increase of 60%. Results of this study showed how the foliar application of MLE was effective in improving various nutraceutical parameters, in particular in kale, because it appears to be a species-specific response.

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