scholarly journals Kinetic Study on the Preparation of Aluminum Fluoride Based on Fluosilicic Acid

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Gaoxiang Chen ◽  
Xingdong Yang ◽  
Jiyan Qu ◽  
Jianhong Luo ◽  
Zhiye Zhang ◽  
...  
Keyword(s):  
Low Cost ◽  
Interface Reaction ◽  
Diffusion Reaction ◽  
Internal Diffusion ◽  
Core Model ◽  
Aluminum Fluoride ◽  
Phosphate Ore ◽  
Mechanism Model ◽  
Product Characterization ◽  
Fluosilicic Acid

Abstract Reasonable mathematical derivation and mechanism model in the process of producing aluminum fluoride by fluosilicic acid is the key to the industrial treatment of fluorine resources in the tail gas of phosphate ore. In this work, aluminum fluoride was generated directly by fluosilicic acid to extract fluorine from the tail gas of phosphate rock. The uncreated-core model dominated by interfacial reaction and the uncreated-core model dominated by internal diffusion-reaction were then respectively utilized to describe the reaction kinetics of the generation of aluminum fluoride. The result showed that the uncreated-core model was dominated by interface reaction and internal diffusion, the apparent reaction order n = 1, and the activation energy Ea = 30.8632 kJ . mol–1. Product characterization and kinetic analysis were employed to deduce the reaction mechanism of preparing aluminum fluoride. The theoretical basis for the low-cost recycling of fluorine resources in the tail gas of industrial phosphate ore was provided in this work.

Research on CO2 EOR Mechanism and Application in Shengli Oilfield

2011 ◽  
Vol 474-476 ◽  
pp. 744-747
Author(s):  
Guang Zhong Lv ◽  
Jian Zhang ◽  
Feng Wang ◽  
Guang Hong Yan ◽  
Xin Jun Zhang
Keyword(s):  
Low Cost ◽  
Oil Field ◽  
Core Model ◽  
Test Block ◽  
Oil Reservoir ◽  
Oil Viscosity ◽  
Shengli Oilfield ◽  
Expansion Mechanism

As one kind of oil expellant in improving the recovery ration of oil reservoir (EOR), CO2 flooding has merits such as extensive adaptability, low cost, high recoverability, and it will become one main way of EOR in future. In this paper, the EOR mechanism of CO2 flooding has been studied correspond to the geologic conditions in Shengli oil field, which includes three parts: mechanism of expansion, mechanism of reduce oil viscosity and displacement experiment of long core model. Moreover, the detailed process of the test block description of CO2 flooding in Shengli oil field has been set forth. Through the application in Shengli oil field proves that the EOR mechanism of CO2 flooding is right and suits for geologic conditions in Shengli oil field.

scholarly journals Research Progress on the Applications of Electrospun Nanofibers in Catalysis

Catalysts ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 9
Author(s):  
M. Olga Guerrero-Pérez
Keyword(s):  
Low Cost ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Electrospun Nanofibers ◽  
Internal Diffusion ◽  
Research Progress ◽  
Bibliographic Analysis ◽  
Low Resistance ◽  
Electro Catalysis

During the last two decades, electrospinning has become a very popular technique for the fabrication of nanofibers due to its low cost and simple handling. Nanofiber materials have found utilization in many areas such as medicine, sensors, batteries, etc. In catalysis, these materials also present important advantages, since they present a low resistance to internal diffusion and a high surface area to volume ratio. These advantages are mainly due to the diameter–length proportion. A bibliographic analysis on the applications of electrospun nanofibers in catalysis shows that there are two important groups of catalysts that are being investigated, based on TiO2 and in carbon materials. The main applications found are in photo- and in electro-catalysis. The present study contributes by reviewing these catalytic applications of electrospun nanofibers and demonstrating that they are promising materials as catalysts, underlining some works to prove the advantages and possibilities that these materials have as catalysts. On one hand, the possibilities of synthesis are almost infinite, since with coaxial electrospinning quite complex nanofibers with different layers can be prepared. On the other hand, the diameter and other properties can be controlled by monitoring the applied voltage and other parameters during the synthesis, being quite reproducible procedures. The main advantages of these materials can be grouped in two: one related to their morphology, as has been commented, relative to their low resistance and internal diffusion, that is, their fluidynamic behavior in the reactor; the second group involves advantages related to the fact that the active phases can be nanoscaled and dispersed, improving the activity and selectivity in comparison with conventional catalytic materials with the same chemical composition.

scholarly journals STE-AMM: Secret Twist Encryption Standard Access Mechanism Model in Cloud Environment

2021 ◽  
pp. 111-117
Author(s):  
Sameer Sameer ◽  
◽  
Harish Rohil
Keyword(s):  
Digital Signature ◽  
Low Cost ◽  
Advanced Encryption Standard ◽  
Cloud Environment ◽  
Dynamic Nature ◽  
Random Size ◽  
Mechanism Model ◽  
Diffie Hellman ◽  
Secret Keys ◽  
Group Module

The advent of the cloud computing has provided the opportunity for various organizations and enterprises to store the data effectively at low cost. With the advancement, the cloud environment manages to have mutli-users to access the data in the cloud based on their request. The requests and the activities of users are monitored and controlled by the group manager based on the roles of them. However due to the dynamic nature of the multi -user clouds result in challenges for ensuring the security of the cloud. Additionally, the revocation of existing users often results in increased overheads. A novel framework of Secret Twisted Encryption based access mechanism model (STE-AMM) is proposed to resolve these issues with two modules. The Square Decisional Diffie-Hellman (SDDH) technique is employed to generate the digital signature for users and used to govern the user in group module. The secret keys to secure the data is generated with the STE algorithm which is the improved Advanced Encryption Standard (AES) and used in the data module. The proposed STE-AMM framework is implemented and evaluated with the metrics of time and cost. The obtained results showed that the performance of the proposed framework is effective than the existing models for securing the data in the cloud. The proposed framework may be enhanced with random size for signature and security key.

scholarly journals Portable continuous wave Doppler ultrasound for primary healthcare in South Africa: can the EUnetHTA Core Model guide evaluation before technology adoption?

2020 ◽  
Author(s):  
Debjani Mueller ◽  
Robert C Pattinson ◽  
Tsakane Musa Hlongwane ◽  
Reinhard Busse ◽  
Dimitra Panteli
Keyword(s):  
South Africa ◽  
Doppler Ultrasound ◽  
Primary Healthcare ◽  
Continuous Wave ◽  
Stakeholder Participation ◽  
Low Cost ◽  
Healthcare Setting ◽  
Assessment Process ◽  
Core Model ◽  
Continuous Wave Doppler

Abstract Background: This study had a threefold aim: to test the value of stakeholder involvement in HTA to reduce the evidence gaps and interpret findings; applicability of the EUnetHTA Core Model (CM) in South Africa on a medical device and thus ultimately provide a first overview of evidence for potential widespread adoption of the technology in a primary health care setting. Used in primary healthcare setting for obstetric use, the technology under assessment is a low-cost continuous wave Doppler ultrasound.Methods: To substantiate the evidence obtained from the literature different stakeholders were identified and consulted. The scoping of the assessment was defined by involving the policy makers to select the domains and the analogous questions relevant to the ultrasound and its use. Additionally, hospital managers were invited to respond to dichotomous questions on the criteria for procurement. The evidence generated from the four steps was used to populate the high-ranked assessment elements of the CM. Results: The HTA took into account the clinical benefit in screening low-risk pregnant women in primary healthcare settings using the technology. It incorporated the evidence on organizational, ethical, and social value of its use together with effectiveness, safety, and cost-effectiveness of the technology. The domains on “health problem” and “safety” had a higher rank than the rest of the nine domains. Conclusions: A multi-stakeholder participation in the assessment process provided the necessary transparency and accountability, thus improving the quality of the recommendation resulting from the assessment. The collection of robust evidence and analysis post-introduction will enable the determination of the value of the technology in real-world settings.

Interface Reaction between Ti3Al-based Alloy and Oxide Mold

2015 ◽  
Vol 816 ◽  
pp. 562-566
Author(s):  
Luo Qian
Keyword(s):  
Interfacial Reaction ◽  
Reaction Layer ◽  
Investment Casting ◽  
Interface Reaction ◽  
Element Distribution ◽  
Diffusion Reaction ◽  
Thick Wall ◽  
Mold Material ◽  
Thin Wall ◽  
Interfacial Reaction Layer

Ti3Al based alloys are light and high-temperature materials, having potential wide applications in the aerospace and the aeronautical industries. Molten Ti is lively, and it is easy to react with the mold material during in the investment casting, and hence to form casting defects such as α contaminated layer in the metal near the surface and gas porosity, resulting in the deterioration of the surface quality and castings mechanical properties. Therefore, the mechanism of interfacial reaction between Ti3Al-based alloys and mold is necessary to study. In this paper, the interface reaction samples of Ti-24Al-15Nb-1Mo alloy and ZrO2(Y2O3stabilized) mold were prepared by actually investment casting. Optical microscopy, SEM, EMPA and micro-hardness tests were used to study the microstructures at metal side of interface, consider the element distribution and discuss the interfacial reaction mechanism. The results show that there is interface reaction between Ti-24Al-15Nb-1Mo alloy and ZrO2(Y2O3stabilized) mold, and it belongs to the typical bilateral diffusion reaction. The elements of Zr, Y, O diffuse into molten metal, at the same time, the matrix elements spread to the oxide mold, then form interfacial reaction layer. It has been found that the interfacial reaction was not uniform in the whole interface. In the thick-wall of castings, the interfacial reaction layer was thicker, and in thin-wall, the interfacial reaction layer was thinner.

Design of Protective Coatings for Glass Lens Molding

2007 ◽  
Vol 364-366 ◽  
pp. 655-661 ◽  
Author(s):  
Kung Jeng Ma ◽  
H.H. Chien ◽  
W.H. Chuan ◽  
Choung Lii Chao ◽  
K.C. Hwang
Keyword(s):  
High Temperature ◽  
Protective Coatings ◽  
Optical Glass ◽  
Low Cost ◽  
Interface Reaction ◽  
Molding Process ◽  
Ceramic Substrates ◽  
Glass Molding ◽  
Operation Temperature ◽  
Glass Lens

The glass molding process is considered to have a great potential for the mass production of aspherical glass lenses with high precision and low cost. However, glass molding has a serious problem of mold sticking with glass which needs to be resolved. This research investigates the interface reaction between glass and mold by high temperature wetting experiment, which provides the reference for the designing anti-stick coatings. The SUMITA K-PSK200 optical glass gobs with low Tg were used in this study. The influence of operation temperature, ambient gas, substrate materials, and thin film composition on wettability of glass at high temperature were studied. The results show that the higher the temperature, the smaller the wetting angle between glass gob and substrate could be observed. This indicates that severe interface chemical reaction occured and resulted in the loss of transparency in glass appearance. The wetting experiment in nitrogen ambient improved the sticking situation. The combination of chemically stable substrates and coatings, such as Sapphire (substrate) / GaN (film) and Glass (substrate) / Al2O3 (film) can achieve the best antistick propose. The precious metal films, such as Pt, Ir, coated on the ceramic substrates can effectively reduce the interface reaction between the glass and substrates.

scholarly journals KINETICS OFPYRROLE FORM TICS OFPYRROLE FORMATIONFROM A TIONFROM ACETYLENE, AMMONIA AND AMINES

2019 ◽  
Vol 2018 (4) ◽  
pp. 24-29
Author(s):  
U Shokirov ◽  
◽  
S Turabjanov ◽  
Rakhimova ◽  
F Badriddinova
Keyword(s):  
Temperature Gradient ◽  
Internal Diffusion ◽  
Aluminum Fluoride ◽  
Reaction Conditions ◽  
Porous Catalyst ◽  
Thiele Modulus ◽  
External Diffusion ◽  
Research Findings

The research findings of the pyrrole formation from acetylene, ammonia and amines varying catalysts and reaction conditions have been studied in the work. The cadmium catalysts developed by us selectively lead to pyrroleformation using aluminum fluoride as a promoter. The change in the rate of acetylene consumption depending on the weight of the catalyst according to the Boreskov criterion shows that external diffusion does not influence under the conditions of T-573K and P_ (C_2 H_2) = 0.1 atm. The values of the rate of acetylene consumption of at 4, 2, 1, 0.5 mm sizes of catalyst grains with similar conditions, internal diffusion does not influence on the observed rate of acetylene consumption. Calculation on the Thiele modulus shows that the reaction of acetylene consumption does not experience intradiffusion inhibition. The presence of a noticeable amount of macropores in the porous catalyst grain eliminates the appearance of a temperature gradient and causes a high kinetic ability of the reaction

scholarly journals Portable Continuous Wave Doppler Ultrasound for Primary Healthcare in South Africa: Can the EUnetHTA Core Model Guide Evaluation Before Technology Adoption?

2020 ◽  
Author(s):  
Debjani Mueller ◽  
Robert C Pattinson ◽  
Tsakane Musa Hlongwane ◽  
Reinhard Busse ◽  
Dimitra Panteli
Keyword(s):  
South Africa ◽  
Primary Healthcare ◽  
Continuous Wave ◽  
Stakeholder Participation ◽  
Low Cost ◽  
Stakeholder Involvement ◽  
Healthcare Setting ◽  
Assessment Process ◽  
Core Model ◽  
Continuous Wave Doppler

Abstract Background: This study had a threefold aim: to test the value of stakeholder involvement in HTA to reduce the evidence gaps and interpret findings; applicability of the EUnetHTA Core Model (CM) in South Africa on a medical device and thus ultimately provide a first overview of evidence for potential widespread adoption of the technology in a primary health care setting. Used in primary healthcare setting for obstetric use, the technology under assessment is a low-cost continuous wave Doppler ultrasound.Methods: To substantiate the evidence obtained from the literature different stakeholders were identified and consulted. The scoping of the assessment was defined by involving the policy makers to select the domains and the analogous questions relevant to the ultrasound and its use. Additionally, hospital managers were invited to respond to dichotomous questions on the criteria for procurement. The evidence generated from the four steps was used to populate the high-ranked assessment elements of the CM. Results: The HTA took into account the clinical benefit in screening low-risk pregnant women in primary healthcare settings using the technology. It incorporated the evidence on organizational, ethical, and social value of its use together with effectiveness, safety, and cost-effectiveness of the technology. The domains on “health problem” and “safety” had a higher rank than the rest of the nine domains. Conclusions: A multi-stakeholder participation in the assessment process provided the necessary transparency and accountability, thus improving the quality of the recommendation resulting from the assessment. The collection of robust evidence and analysis post-introduction will enable the determination of the value of the technology in real-world settings.

scholarly journals One-dimensional isothermal multicomponent diffusion-reaction model and its application to methanol synthesis over commercial Cu-based catalyst

2015 ◽  
Vol 17 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Kun Lei ◽  
Hongfang Ma ◽  
Haitao Zhang ◽  
Weiyong Ying ◽  
Dingye Fang
Keyword(s):  
Methanol Synthesis ◽  
Reaction Rate ◽  
Multicomponent Diffusion ◽  
Reaction Model ◽  
Diffusion Reaction ◽  
Internal Diffusion ◽  
One Dimensional ◽  
Effectiveness Factors ◽  
Global Reaction ◽  
Hydrogenation Of Co

Abstract The present work was a study on global reaction rate of methanol synthesis. We measured experimentally the global reaction rate in the internal recycle gradientless reactor over catalyst SC309. The diffusion-reaction model of methanol synthesis was suggested. For model we chose the hydrogenation of CO and CO2 as key reaction. CO and CO2 were key components in our model. The internal diffusion effectiveness factors of CO and CO2 in the catalyst were calculated by the numerical integration. A comparison with the experiment showed that all the absolute values of the relative error were less than 10%. The simulation results showed that decreasing reaction temperature and catalyst diameter were conducive to reduce the influence of the internal diffusion on the methanol synthesis.

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