scholarly journals Zinc and lead recovery from jarosite residues produced in zinc hydrometallurgy by vacuum reduction and distillation

2018 ◽  
Vol 7 (6) ◽  
pp. 552-557 ◽  
Author(s):  
Jin Li ◽  
Hongzhou Ma
Keyword(s):  
Heating Temperature ◽  
Holding Time ◽  
Contributing Factors ◽  
Environment Friendly ◽  
Lead Recovery ◽  
Key Factor ◽  
Lime Powder ◽  
Zinc Hydrometallurgy ◽  
The Relationship ◽  
Coke Powder

Abstract Jarosite residues in zinc hydrometallurgy are considered as hazardous waste as they contain heavy metals such as Zn and Pb. A novel vacuum reduction and distillation process has been put forward to recover Zn and Pb from jarosite residues. Four main factors including the amount of coke powder, amount of lime powder, heating temperature, and holding time which have an influence on volatilization of Zn and Pb were studied in this paper by the statistical software JMP. The results show that heating temperature is the key factor among the four contributing factors. By examination of the relationship between the four factors and the volatilization of Zn and Pb, it is indicated that a heating temperature of 1000°C, holding time of 90 min, and addition of 29.6% coke powder and 13% lime powder to the residues led to optimum ratios of 99.4% of both Zn and Pb volatilization. The results show that this process is an effective method in dealing with zinc, lead, and iron in jarosite residues and it is an environment-friendly process.

Numerical Simulation of Concentration Field for Be/00Cr17Ni14Mo2 Stainless Steel by Diffusion Bonding

2015 ◽  
Vol 1120-1121 ◽  
pp. 1129-1133
Author(s):  
Hui Li ◽  
Xuan Wang ◽  
Yong Zhu ◽  
Peng Cheng Zhang
Keyword(s):  
Stainless Steel ◽  
Diffusion Layer ◽  
Diffusion Bonding ◽  
Heating Temperature ◽  
Concentration Field ◽  
Bonding Interface ◽  
Holding Time ◽  
The Finite Element Method ◽  
The One ◽  
The Relationship

In order to provide the best technic parameter for hot pressing, the distributions of Fe and Be near the Be and 00Cr17Ni14Mo2 stainless steel (Be/SS) diffusion bonding interface under different technic parameter were simulated by the finite element method and measured by means of scanning auger microspectroy (AES). The simulated results were compared with experimental value, The distributions of Fe and Be near the Be/SS diffusion bonding interface and the relationships between the width of diffusion layer, the heating temperature, the holding time and the pressure were also discussed. The results indicate that under the condition of heating temperature 1323K and 1023K with diffusion pressure 60MPa and holding time 7200s, respectively, the simulated distributions of Fe and Be near the Be/SS diffusion bonding interface fit with the experimence values, and the width of diffusion layer at 1323K is about 2.5 times the one at 1023K. Under the condition of heating temperature 1023K with holding time 7200s, the width of diffusion layer measured at 30MPa, 40MPa, 50MPa and 60MPa is fit well with the simulated results and the relationship between the width of diffusion layer (x/μm) and the diffusion pressure (p/MPa) follows the eqution 0fx=-1.5×10-2p2+2.8275p-0.1575. Under the condition of heating temperature 1023K with diffusion pressure 60MPa, the simulation curve between the width of diffusion layer (x/μm) and the holding time (t/s) follows the eqution 0fx=10t3-60.571t2+135.64t+0.2143.

scholarly journals β-Si3N4 Microcrystals Prepared by Carbothermal Reduction-Nitridation of Quartz

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3622 ◽  
Author(s):  
Meng Zhang ◽  
Zhi Chen ◽  
Juntong Huang ◽  
Saifang Huang ◽  
Zhihui Hu ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Formation Mechanism ◽  
Carbothermal Reduction ◽  
Single Phase ◽  
Heating Temperature ◽  
Holding Time ◽  
Spectral Emission ◽  
Reaction Parameters ◽  
Future Potential ◽  
Coke Powder

Single phase β-Si3N4 with microcrystals was synthesized via carbothermal reduction-nitridation (CRN) of quartz and carbon coke powder as starting materials. The effects of reaction parameters, i.e., heating temperature, holding time, C/SiO2 ratio, Fe2O3 additive and β-Si3N4 seeds on the phase transformation and morphology of products were investigated and discussed. Rather than receiving a mixture of both α- and β- phases of Si3N4 in the products, we synthesized powders of β-Si3N4 single polymorph in this work. The mechanism for the CRN synthesis of β-Si3N4 from quartz and the formation mechanism of Fe3Si droplets were discussed. We also firstly reported the formation of Fe3Si Archimedean solids from a CRN process where Fe2O3 was introduced as additive. Comparing to the gear-like short columnar morphology observed in samples without β-Si3N4 seeding, the addition of β-Si3N4 seeds led to an elongated morphology of final products and much finer widths. In addition, the β-Si3N4 microcrystals exhibited a violet‒blue spectral emission range, which could be highly valuable for their future potential optoelectronic applications.

scholarly journals Does a National Park Enhance the Environment-Friendliness of Tourists as an Ecotourism Destination?

2021 ◽  
Vol 18 (16) ◽  
pp. 8321
Author(s):  
Eunseong Jeong ◽  
Taesoo Lee ◽  
Alan Dixon Brown ◽  
Sara Choi ◽  
Minyoung Son
Keyword(s):  
National Parks ◽  
Natural Environment ◽  
Behavioral Intention ◽  
National Park ◽  
Structural Equation ◽  
Environmental Concern ◽  
Equation Modeling ◽  
Environment Friendly ◽  
Sustainable Environment ◽  
The Relationship

Governments have designated national parks to protect the natural environment against ecosystem destruction and improve individuals’ emotional and recreational life. National parks enhance environment-friendly awareness by conducting ecotourism activities and individuals with environment-friendly awareness are inclined to continue to visit national parks as ecotourism destinations. The New Environmental Paradigm (NEP) is a widely used measure of environmental concern, suitable for measuring the environment-friendly attitude and revisit intention of visitors of national parks. Therefore, the study carried out structural equation modeling (SEM) to investigate the relationship between the NEP, national park conservation consciousness and environment-friendly behavioral intention. Based on the results, an implication is presented to induce national parks to cultivate individual environment-friendly awareness and for visitors to pursue sustainable, environment-friendly tourism behavior. The findings indicate that national parks are to expand educational programs and facilities for eco-tourists visiting national parks to maintain a balanced relationship between themselves and nature and have a strong environmental awareness to preserve the natural environment.

scholarly journals Estimation of resistance force at steady-state sinkage for cylindrical wheel-typed lunar/planetary exploration rovers with function of push–pull locomotion

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Daisuke Fujiwara ◽  
Naoki Tsujikawa ◽  
Tetsuya Oshima ◽  
Kojiro Iizuka
Keyword(s):  
Steady State ◽  
Estimation Method ◽  
Planetary Exploration ◽  
Experimental Result ◽  
Resistance Force ◽  
Estimation Model ◽  
Loose Soil ◽  
Key Factor ◽  
The Relationship ◽  
Resistance Forces

Abstract Planetary exploration rovers have required a high traveling performance to overcome obstacles such as loose soil and rocks. Push-pull locomotion rovers is a unique scheme, like an inchworm, and it has high traveling performance on loose soil. Push-pull locomotion uses the resistance force by keeping a locked-wheel related to the ground, whereas the conventional rotational traveling uses the shear force from loose soil. The locked-wheel is a key factor for traveling in the push-pull scheme. Understanding the sinking behavior and its resistance force is useful information for estimating the rover’s performance. Previous studies have reported the soil motion under the locked-wheel, the traction, and the traveling behavior of the rover. These studies were, however, limited to the investigation of the resistance force and amount of sinkage for the particular condition depending on the rover. Additionally, the locked-wheel sinks into the soil until it obtains the required force for supporting the other wheels’ motion. How the amount of sinkage and resistance forces are generated at different wheel sizes and mass of an individual wheel has remained unclear, and its estimation method hasn’t existed. This study, therefore, addresses the relationship between the sinkage and its resistance force, and we analyze and consider this relationship via the towing experiment and theoretical consideration. The results revealed that the sinkage reached a steady-state value and depended on the contact area and mass of each wheel, and the maximum resistance force also depends on this sinkage. Additionally, the estimation model did not capture the same trend as the experimental results when the wheel width changed, whereas, the model captured a relatively the same trend as the experimental result when the wheel mass and diameter changed.

Numerical Simulation and Process Optimization of Automotive Friction Materials in Warm Pressing Forming

2013 ◽  
Vol 788 ◽  
pp. 57-60
Author(s):  
Chun Cao ◽  
Chun Dong Zhu ◽  
Chen Fu
Keyword(s):  
Process Optimization ◽  
Heating Temperature ◽  
Maximum Energy ◽  
Heating Time ◽  
Product Performance ◽  
Forming Process ◽  
Friction Materials ◽  
Forming Technology ◽  
The Relationship ◽  
Temperature Heating

Warm pressing forming technology has been gradually applied to the forming of automotive friction materials. How to ensure product performance to achieve the target at the same time achieve the maximum energy saving is the research focus of this study. In this paper, by using finite element method, the field of automotive friction materials in warm pressing forming was analyzed, reveals the relationship between the temperature field and the heating temperature/heating time. Furthermore, the energy consumption was analyzed and compared it with hot pressing forming process. The results will have significant guiding to the process optimization in warm pressing forming.

scholarly journals Parkinson’s Disease and the COVID-19 Pandemic

2021 ◽  
pp. 1-14
Author(s):  
Conor Fearon ◽  
Alfonso Fasano
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Indirect Effects ◽  
Mortality Data ◽  
Contributing Factors ◽  
Scientific Rigor ◽  
The Impact ◽  
The Relationship ◽  
Non Motor Symptoms ◽  
Convincing Data

Studies focusing on the relationship between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), coronavirus disease 2019 (COVID-19), and Parkinson’s disease (PD) have provided conflicting results. We review the literature to investigate: 1) Are PD patients at higher risk for contracting COVID-19 and are there specific contributing factors to that risk? 2) How does COVID-19 affect PD symptoms? 3) How does COVID-19 present in PD patients? 4) What are the outcomes in PD patients who contract COVID-19? 5) What is the impact of COVID-19 on PD care? 6) Does COVID-19 increase the risk of developing PD? A literature search was performed from 1979 to 2020 using the terms: ‘Parkinson’s disease’ and ‘parkinsonism’ combined with: ‘COVID-19’; ‘SARS-CoV-2’ and ‘coronavirus’. It does not appear that PD is a specific risk factor for COVID-19. There is evidence for direct/indirect effects of SARS-CoV-2 on motor/non-motor symptoms of PD. Although many PD patients present with typical COVID-19 symptoms, some present atypically with isolated worsening of parkinsonian symptoms, requiring increased anti-PD therapy and having worse outcomes. Mortality data on PD patients with COVID-19 is inconclusive (ranging from 5.2%to 100%). Patients with advanced PD appear to be particularly vulnerable. Single cases of acute hypokinetic-rigid syndrome have been described but no other convincing data has been reported. The rapidity with which COVID-19 has swept across the globe has favored the proliferation of studies which lack scientific rigor and the PD literature has not been immune. A coordinated effort is required to assimilate data and answer these questions in larger PD cohorts.

An Empirical Research on the Relationship between Real Estate Prices and Inflation

2011 ◽  
Vol 55-57 ◽  
pp. 1992-1996
Author(s):  
Tie Qun Li
Keyword(s):  
Real Estate ◽  
Stock Prices ◽  
Test Analysis ◽  
Social Demand ◽  
The Real Estate ◽  
Key Factor ◽  
Negative Effect ◽  
Labor Service ◽  
Real Estate Prices ◽  
The Relationship

The former researches referring to inflation and real estate prices concentrated mainly on the stock prices rather than the real estate prices. Owing to the enlarging ratio of real estate industry in national economy with each passing day, as well as the overheating real estate prices in recent years, the relationship between real estate prices and inflation is particularly vital to the monetary policy making for the monetary authorities. According to the test analysis of data from 2001 to 2009, it is found that real estate prices is Granger Cause of inflation while inflation is not the Granger Cause of real estate prices in this paper. Through the Effects of Wealth, Credit and Tobin, real estate prices drive the growth of social consumption and investments and expand the total social demand which possess an positive effect on inflation; nevertheless the rising of real estate prices causes the rising of currency for real estate purchasing, which, under the circumstance of that currency supply remains, will inevitably bring about the reduction of currency for other consumption and investments and restrain the total social demand which would mean a suppression of continuous rising of prices of other commodity and labor service. All these show that real estate also has a negative effect on inflation. The cancellations between the two effects make the long-term influence real estate bearing on inflation is not obvious. The experimental results indicate that when the price of real estate rises 1%, inflation only rises 0.058%. Consequently, a strict controlling of the amount of money issued is the key factor for keeping the over rapid rising of real estate prices from leading to inflation.

COVID-19 AND STROKE: POSSIBLE CAUSES AND PATHOGENESIS (REVIEW)

Vestnik ◽  
2021 ◽  
pp. 103-106
Author(s):  
А.Е. Кожашева ◽  
С.О. Белесбек ◽  
Д.Ж. Абдимитова ◽  
Б.М. Сакен ◽  
А.П. Бориходжаева ◽  
...  
Keyword(s):  
Preventive Measures ◽  
Cerebrovascular Disorders ◽  
Endothelial Damage ◽  
Cytokine Release ◽  
Contributing Factors ◽  
Acute Cerebrovascular Accident ◽  
Von Willebrand ◽  
The Relationship ◽  
Willebrand Factor ◽  
D Dimer

Появляются доказательства того, что COVID-19 может вызывать выброс цитокинов, состояние гиперкоагуляции и повреждение эндотелия, которое может привести к острому нарушению мозгового кровообращения (ОНМК). В данной статье авторы обсуждают взаимосвязь между COVID-19 и ОНМК, и о возможных факторах, способствующих возникновению инсульта. Как свидетельствует увеличение D-димера, фибриногена, фактора VIII и фактора фон Виллебранда, инфекция SARS-CoV-2 вызывает коагулопатию, нарушает функцию эндотелия и способствует состоянию гиперкоагуляции. В совокупности это предрасполагает пациентов к цереброваскулярным нарушениям. Механизм, лежащий в основе COVID-19 и инсульта, требует дальнейшего изучения, равно как и разработка эффективных терапевтических или профилактических мер. Evidence is emerging that COVID-19 can cause cytokine release, hypercoagulable states, and endothelial damage that can lead to acute cerebrovascular accident (ACVI). In this article, the authors discuss the relationship between COVID-19 and stroke and the possible contributing factors to stroke. As evidenced by an increase in D-dimer, fibrinogen, factor VIII and von Willebrand factor, SARS-CoV-2 infection causes coagulopathy, disrupts endothelial function and hypercoagulability. Collectively, this predisposes patients to cerebrovascular disorders. The mechanism underlying COVID-19 and stroke requires further study, as does the development of effective therapeutic or preventive measures.

Iranian Coaches Forgiveness and Relationship Quality to Their Athletes

2021 ◽  
pp. 1-8
Author(s):  
Hassan Gharayagh Zandi ◽  
Sahar Zarei ◽  
Mohammad Ali Besharat ◽  
Davoud Houminiyan sharif abadi ◽  
Ahmad Bagher Zadeh
Keyword(s):  
Relationship Quality ◽  
Structural Equation ◽  
Equation Modeling ◽  
Data Sets ◽  
Mediating Role ◽  
Interpersonal Behaviors ◽  
Key Factor ◽  
The Relationship

Coaching has often been viewed as a context within which coaches operate to largely bring about changes in athlete’s performance and flourishing. One key factor to successful outcomes in coaching is the quality of the relationship between coaches and athletes. The coach–athlete relationship is at the heart of coaching; however, limited studies have been conducted on its antecedents. The aim of this study was to investigate the relationship between coaches’ forgiveness and perceived relationship quality toward their athletes through verifying the mediating role of interpersonal behaviors of coaches. A total of 270 Iranian coaches participated in the survey, and the data sets were analyzed using structural equation modeling. Results revealed that forgiveness positively predicted the coaches’ perceived relationship quality with their athletes, and this pathway was mediated by the coaches’ interpersonal behaviors.

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