scholarly journals USE OF MECHANOCHEMICAL ACTIVATION TO CONTROL RHEOLOGICAL PROPERTIES OF MOULDING PASTES FOR CATALYSTS AND SORBENTS EXTRUSION

2017 ◽  
Vol 60 (1) ◽  
pp. 102
Author(s):  
Nataliya Svyatenko ◽  
Valery Yu. Prokof’ev ◽  
Natalya E. Gordina
Keyword(s):  
Rheological Properties ◽  
Mechanochemical Activation ◽  
Solid Phase ◽  
Critical Shear Stress ◽  
Coherent Scattering ◽  
Coherent Scattering Region ◽  
Shear Loading ◽  
Flow Index ◽  
Wide Range ◽  
The Impact

For citation:Svyatenko N., Prokof’ev V.Yu., Gordina N.E. Use of mechanochemical activation to control rheological properties of moulding pastes for catalysts and sorbents extrusion. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 1. P. 102-107.The influence humidity, grinding and mechanical activation of the solid phase on the rheological properties of the molding paste for extrusion of catalysts and sorbents was studied. The following parameters of the molding pastes were investigated, namely the coagulation structure strength, the flow index, the maximum plastic viscosity, the critical shear stress, plasticity, the r (stuelaxation period), the ratio of deformations. In order to characterize the degree of mechanochemical activation, the dimension of the coherent scattering region and the microdeformations value were used. Increasing the degree of mechanochemical activation of the solid phase was shown to allow controlling the properties of molding pastes in a more wide range. In the technology of extruded catalysts and sorbents, the mills-activators with the impact-shear loading are proposed to use. The mills with an average value of power density (up to 6 kW/kg) were recommended.

scholarly journals Multivariate Assessment of Procedures for Molecularly Imprinted Polymer Synthesis for Pesticides Determination in Environmental and Agricultural Samples

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7078
Author(s):  
Mariusz Marć ◽  
Marta Bystrzanowska ◽  
Katarzyna Pokajewicz ◽  
Marek Tobiszewski
Keyword(s):  
Sample Preparation ◽  
Solid Phase ◽  
Food Samples ◽  
Mechanical Resistance ◽  
Molecularly Imprinted ◽  
Innovative Strategies ◽  
Wide Range ◽  
Analytical Procedures ◽  
Pre Treatment ◽  
The Impact

In the case of quantitative and qualitative analysis of pesticides in environmental and food samples, it is required to perform a sample pre-treatment process. It allows to minimalize the impact of interferences on the final results, as well as increase the recovery rate. Nowadays, apart from routinely employed sample preparation techniques such as solid-phase extraction (SPE) or solid-phase microextraction (SPME), the application of molecularly imprinted polymers (MIPs) is gaining greater popularity. It is mainly related to their physicochemical properties, sorption capacity and selectivity, thermo-mechanical resistance, as well as a wide range of polymerization techniques allowing to obtain the desired type of sorption materials, adequate to a specific type of pesticide. This paper targets to summarize the most popular and innovative strategies since 2010, associated with the MIPs synthesis and analytical procedures for pesticides determination in environmental and food samples. Application of multi-criteria decision analysis (MCDA) allows for visualization of the most beneficial analytical procedures in case of changing the priority of each step of analysis (MIPs synthesis, sample preparation process—pesticides extraction, chromatographic analysis) bearing in mind metrological and environmental issues.

scholarly journals Rheological Properties of Typical Ceramic Slurries Used in the Lost Wax Technology

2017 ◽  
Vol 17 (1) ◽  
pp. 197-201
Author(s):  
J. Kolczyk ◽  
Ł. Jamrozowicz ◽  
N. Kaźnica
Keyword(s):  
Aluminum Oxide ◽  
Rheological Properties ◽  
Newtonian Fluid ◽  
Investment Casting ◽  
Solid Phase ◽  
Shear Velocity ◽  
Flow Curves ◽  
Casting Technology ◽  
Wide Range ◽  
Different Temperatures

Abstract The results of investigations of the rheological properties of typical ceramic slurries used in the investment casting technology - the lost wax technology are presented in the paper. Flow curves in the wide range of shear velocity were made. Moreover, viscosity of ceramic slurries depending on shearing stresses was specified. Tests were performed under conditions of three different temperatures 25, 30 and 35°C, which are typical and important in the viewpoint of making ceramic slurries in the investment casting technology. In the light of the performed investigations can be said that the belonging in group of Newtonian or Non - Newtonian fluid is dependent on content of solid phase (addition of aluminum oxide) in the whole composition of liquid ceramic slurries.

scholarly journals Impact of a Random Sequence of Debris Flows on Torrential Fan Formation

Geosciences ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 64 ◽  
Author(s):  
Nejc Bezak ◽  
Jošt Sodnik ◽  
Matjaž Mikoš
Keyword(s):  
Debris Flow ◽  
Numerical Simulations ◽  
Rheological Properties ◽  
Debris Flows ◽  
Random Sequence ◽  
Rheological Parameters ◽  
Model Parameters ◽  
Maximum Height ◽  
Wide Range ◽  
The Impact

Debris flows with different magnitudes can have a large impact on debris fan characteristics such as height or slope. Moreover, knowledge about the impact of random sequences of debris flows of different magnitudes on debris fan properties is sparse in the literature and can be improved using numerical simulations of debris fan formation. Therefore, in this paper we present the results of numerical simulations wherein we investigated the impact of a random sequence of debris flows on torrential fan formation, where the total volume of transported debris was kept constant, but different rheological properties were used. Overall, 62 debris flow events with different magnitudes from 100 m3 to 20,000 m3 were selected, and the total volume was approximately 225,000 m3. The sequence of these debris flows was randomly generated, and selected debris fan characteristics after the 62 events were compared. For modeling purposes, we applied the Rapid Mass Movement Simulations (RAMMS) software and its debris flow module (RAMMS-DF). The modeling was carried out using (a) real fan topography from an alpine environment (i.e., an actual debris fan in north-west (NW) Slovenia formed by the Suhelj torrent) and (b) an artificial surface with a constant slope. Several RAMMS model parameters were tested. The simulation results confirm that the random sequence of debris flow events has only some minor effects on the fan formation (e.g., slope, maximum height), even when changing debris flow rheological properties in a wide range. After the 62 events, independent of the selected sequence of debris flows, the final fan characteristics were not significantly different from each other. Mann–Whitney (MW) tests and t-tests were used for this purpose, and the selected significance level was 0.05. Moreover, this conclusion applies for artificial and real terrain and for a wide range of tested RAMMS model rheological parameters. Further testing of the RAMMS-DF model in real situations is proposed in order to better understand its applicability and limitations under real conditions for debris flow hazard assessment or the planning of mitigation measures.

scholarly journals Studies on the Efficiency of the Impact of Paraffin Inhibitors on Lowering the WAT Temperature and Reducing the Amount of Paraffin Deposit

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4653
Author(s):  
Sławomir Szuflita ◽  
Michał Pajda ◽  
Jerzy Kuśnierczyk ◽  
Mirosław Wojnicki ◽  
Marcin Warnecki
Keyword(s):  
Crude Oil ◽  
Additional Data ◽  
Solid Phase ◽  
Temperature Drop ◽  
Equilibrium Conditions ◽  
Wax Precipitation ◽  
Solid Paraffin ◽  
Wide Range ◽  
The Impact

This paper discusses the issues of the impact of pressure and temperature on the precipitation of paraffin deposits from reservoir fluids in the presence of previously prepared paraffin inhibitors. Using a properly modified PVT apparatus, the temperature of the beginning of paraffin precipitation (wax appearance temperature—WAT) has been determined, below which the solid paraffin phase was captured on a specialized filter in various temperatures. Based on the conducted experiments, a boundary has been established separating the paraffin area (the presence of paraffins as their solid phase) from an area without paraffin. Measurements of the amount of paraffin using the filter allowed the determination of the WPC (wax precipitation curve), due to which additional data is provided regarding the amount of precipitated paraffin deposit below the WAT. The developed methodology enables to conduct the measurements within a wide range of pressures using the sample saturated with reservoir gas, which can test the crude oil sample that corresponds to the actual production conditions. Most known research methods do not allow such preparation of a sample and conducting the measurements under pressurized conditions; therefore, the produced results are subject to errors. The paper describes also the studies of efficiency and differences in the action of various paraffin inhibitors. Based on the performed research, a comparison was made involving the action of agents under the pressureless conditions of dead oil and pressurized crude oil samples saturated with gas. The performed studies allowed the determination of equilibrium conditions (in a pressure–temperature system), under which deposition of the solid paraffin phase occurs during the use of three various inhibitors. Based on the performed experiments, an area with a paraffin hazard was determined, along with an area without paraffins. Due to the separation of the precipitated solid paraffin phase, an increase in the mass of the paraffin deposit associated with a temperature drop was determined (wax precipitation curve), as well as the impact of the applied inhibitors on its course.

scholarly journals The Lubricity and Rheological Properties of Magnetorheological Fluids

2016 ◽  
Vol 39 (1) ◽  
pp. 141-158
Author(s):  
Emil Nowiński
Keyword(s):  
Magnetic Field ◽  
Rheological Properties ◽  
Solid Phase ◽  
Wear Test ◽  
Magnetorheological Fluids ◽  
Dynamic Rheology ◽  
Wide Range ◽  
Base Liquid

Abstract The article presents results of tribological research carried on four ball tester and dynamic rheometer for different magnetorheological fluids. The wear test was conducted with and without magnetic field. The dynamic rheology measurement was done at wide range of velocity. The inteligent fluids differed from each other by an amount of solid phase and kind of base liquid.

scholarly journals Simulation Study on Dynamics of Hydraulic Turbines Used in Drilling Engineering

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Yijin Zeng ◽  
Jin Wang ◽  
Shidong Ding ◽  
Haobo Zhou ◽  
Yanbin Zang ◽  
...  
Keyword(s):  
External Load ◽  
Solid Phase ◽  
Design Method ◽  
Wide Range ◽  
Aero Engines ◽  
Turbine Design ◽  
Water Turbines ◽  
The Impact ◽  
External Loads ◽  
Starting Torque

Hydroturbines have a very wide range of applications, which are commonly found in wind turbines, water turbines, aero engines, etc. This paper provided a detailed turbine design and a design method of turbine blade shape. Using the CFD (computational fluid dynamics) method, based on the realizable k-ɛ turbulence model and Euler multiphase flow model, the effects of different external loads, blade numbers, blade installation angles, and flow rates on the force condition of turbine and the influence of different solid contents, particle sizes, and densities on turbine performance were studied. The simulation results show that, under the action of fluid, when the starting torque of turbine is larger than the external load, the turbine starts to move, the angular velocity increases until it remains constant, the absolute value of impact force decreases, and the impact torque decreases until it is equal to the external load; while the starting torque of turbine is smaller than the external load, the turbine stays still. The increase of the particle size, content, and density of the solid phase will lead to an increase in the torque and pressure drop of the turbine and ultimately leads to the increase of turbine input, output power, and efficiency.

THE IMPACT OF LEADERSHIP PRACTICES TO TEAM MEMBERS’ SATISFACTION

2009 ◽  
Vol 8 (1) ◽  
Author(s):  
Chalimah .
Keyword(s):  
Conflict Resolution ◽  
Leadership Practices ◽  
Hotel Industry ◽  
Leader Behavior ◽  
Team Leader ◽  
Shop Floor ◽  
Team Members ◽  
Top Executives ◽  
Wide Range ◽  
The Impact

eamwork is becoming increasingly important to wide range of operations. It applies to all levels of the company. It is just as important for top executives as it is to middle management, supervisors and shop floor workers. Poor teamwork at any level or between levels can seriously damage organizational effectiveness. The focus of this paper was therefore to examine whether leadership practices consist of team leader behavior, conflict resolution style and openness in communication significantly influenced the team member’s satisfaction in hotel industry. Result indicates that team leader behavior and the conflict resolution style significantly influenced team member satisfaction. It was surprising that openness in communication did not affect significantly to the team members’ satisfaction.

Stress, anxiety, depression and burnout in frontline health care workers during COVID-19 pandemic: a brief systematic review and new data from Russia

2021 ◽  
Author(s):  
Ekaterina Mosolova ◽  
Dmitry Sosin ◽  
Sergey Mosolov
Keyword(s):  
Risk Factors ◽  
Systematic Review ◽  
Female Gender ◽  
Assessment Tools ◽  
Care Workers ◽  
Younger Age ◽  
Wide Range ◽  
Associated Risk Factors ◽  
Anxiety Depression ◽  
The Impact

During the COVID-19 pandemic, healthcare workers (HCWs) have been subject to increased workload while also exposed to many psychosocial stressors. In a systematic review we analyze the impact that the pandemic has had on HCWs mental state and associated risk factors. Most studies reported high levels of depression and anxiety among HCWs worldwide, however, due to a wide range of assessment tools, cut-off scores, and number of frontline participants in the studies, results were difficult to compare. Our study is based on two online surveys of 2195 HCWs from different regions of Russia during spring and autumn epidemic outbreaks revealed the rates of anxiety, stress, depression, emotional exhaustion and depersonalization and perceived stress as 32.3%, 31.1%, 45.5%, 74.2%, 37.7% ,67.8%, respectively. Moreover, 2.4% of HCWs reported suicidal thoughts. The most common risk factors include: female gender, nurse as an occupation, younger age, working for over 6 months, chronic diseases, smoking, high working demands, lack of personal protective equipment, low salary, lack of social support, isolation from families, the fear of relatives getting infected. These results demonstrate the need for urgent supportive programs for HCWs fighting COVID-19 that fall into higher risk factors groups.

A MODELING SYSTEM FOR CLIMATE CHANGE RISK ASSESSMENT, MANAGEMENT AND HEDGING IN COASTAL AREAS

2017 ◽  
Author(s):  
Sergei Soldatenko ◽  
Sergei Soldatenko ◽  
Genrikh Alekseev ◽  
Genrikh Alekseev ◽  
Alexander Danilov ◽  
...  
Keyword(s):  
Climate Change ◽  
Risk Assessment ◽  
Coastal Areas ◽  
Mitigation Strategies ◽  
System Structure ◽  
The Arctic ◽  
Risk Modeling ◽  
Wide Range ◽  
Adverse Weather ◽  
The Impact

Every aspect of human operations faces a wide range of risks, some of which can cause serious consequences. By the start of 21st century, mankind has recognized a new class of risks posed by climate change. It is obvious, that the global climate is changing, and will continue to change, in ways that affect the planning and day to day operations of businesses, government agencies and other organizations and institutions. The manifestations of climate change include but not limited to rising sea levels, increasing temperature, flooding, melting polar sea ice, adverse weather events (e.g. heatwaves, drought, and storms) and a rise in related problems (e.g. health and environmental). Assessing and managing climate risks represent one of the most challenging issues of today and for the future. The purpose of the risk modeling system discussed in this paper is to provide a framework and methodology to quantify risks caused by climate change, to facilitate estimates of the impact of climate change on various spheres of human activities and to compare eventual adaptation and risk mitigation strategies. The system integrates both physical climate system and economic models together with knowledge-based subsystem, which can help support proactive risk management. System structure and its main components are considered. Special attention is paid to climate risk assessment, management and hedging in the Arctic coastal areas.

The Management of Post-Tonsillectomy Morbidity in Patients With Sleep Apnoea

2019 ◽  
Vol 70 (10) ◽  
pp. 3738-3740
Keyword(s):  
Day Surgery ◽  
Sleep Apnoea ◽  
Integrative Approach ◽  
Multicenter Studies ◽  
Therapeutic Modalities ◽  
Advantages And Disadvantages ◽  
Obstructive Sleep ◽  
Wide Range ◽  
The Impact ◽  
Surgery Center

The Tonsillectomy in children or adults is an intervention commonly encountered in the ENT (Ear Nose and Throat) and Head and Neck surgeon practice. The current tendency is to perform this type of surgery in major ambulatory surgery centers. Two objectives are thus pursued: first of all, the increase of the patient quality of life through the reintegration into the family as quickly as possible and secondly, the expenses associated with continuous hospitalization are reduced. Any tertiary (multidisciplinary) sleep center must ensure the complete diagnosis and treatment (including surgery) of sleep respiratory disorders. Under these conditions the selection of patients and especially the implementation of the specific protocols in order to control the postoperative complications it becomes essential. The present paper describes our experience of tonsillectomy as treatment for selected patients with chronic rhonchopathy (snoring) and mild to moderate obstructive sleep apnoea. It was presented the impact of antibiotics protocols in reducing the main morbid outcomes following tonsillectomy, in our day surgery center. The obtained results can also be a prerequisite for the integrative approach of the patients with sleep apnoea who were recommended surgical treatment. Considering the wide range of therapeutic modalities used in sleep apnoea, each with its specific advantages and disadvantages, more extensive and multicenter studies are needed. Keywords: post-tonsillectomy morbidity, day surgery center, sleep disorders

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