scholarly journals The Impact of Microstructure of Filtration Materials on Its Auto-Activation for Manganese Removal from Groundwater

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 502
Author(s):  
Zbysław Dymaczewski ◽  
Joanna Falkowska ◽  
Angelika Frąckowiak ◽  
Joanna Jeż-Walkowiak ◽  
Justyna Nawrot ◽  
...  
Keyword(s):  
Pore Structure ◽  
Comprehensive Evaluation ◽  
Activation Parameters ◽  
Nitrogen Adsorption ◽  
Silica Sand ◽  
Structure Parameters ◽  
Activation Time ◽  
Manganese Removal ◽  
Wide Range ◽  
The Impact

The study investigates the impact of pore structure parameters of three chemically non-active filtration materials on the auto-activation time and the height of the filtration zone for manganese removal from groundwater. At a technical scale, the activation is a long process which may require a period of up to three months. The process can be shortened by the use of porous filtration materials. In this study, three filtration materials (silica sand, chalcedonite sand, GAC—granulated activated carbon) were investigated using subcritical nitrogen adsorption and mercury injection capillary pressure measurements. These methods provide a comprehensive evaluation of pore structure parameters, including specific surface area (SSA), micro- and mesopore volumes, and an extended range of pore size distribution (PSD). The studied materials provided a wide range of micro- and mesopore volumes as well as SSA. In order to investigate the auto-activation time of filtration material—the time required to achieve the requested quality of the filtrate—and the height of the filtration zone, a pilot experiment was conducted for 1950 h. The pilot installation consisted of three-meters-high (10 cm diameter) filtration columns filled with the tested filtration materials. The results indicate that the internal pore structure and the investigated auto-activation parameters are correlated. Both auto-activation time and the size of the filtration zone were influenced by the mesopore volume and the associated SSA of the tested materials. The micropore volume was less effective in improving the autoactivation parameters. The research results indicated the importance of pore structure characteristics which should be considered prior to time-consuming pilot and technological tests.

scholarly journals Gas Permeability of Cellulose Aerogels with a Designed Dual Pore Space System

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2688 ◽  
Author(s):  
Kathirvel Ganesan ◽  
Adam Barowski ◽  
Lorenz Ratke
Keyword(s):  
Porous Materials ◽  
Cell Walls ◽  
Gas Permeability ◽  
Pore Space ◽  
Nitrogen Adsorption ◽  
Space System ◽  
Fixed Amount ◽  
Hydrophilic Lipophilic Balance ◽  
Wide Range ◽  
The Impact

The gas permeability of a porous material is a key property determining the impact of the material in an application such as filter/separation techniques. In the present study, aerogels of cellulose scaffolds were designed with a dual pore space system consisting of macropores with cell walls composing of mesopores and a nanofibrillar network. The gas permeability properties of these dual porous materials were compared with classical cellulose aerogels. Emulsifying the oil droplets in the hot salt–hydrate melt with a fixed amount of cellulose was performed in the presence of surfactants. The surfactants varied in physical, chemical and structural properties and a range of hydrophilic–lipophilic balance (HLB) values, 13.5 to 18. A wide range of hierarchical dual pore space systems were produced and analysed using nitrogen adsorption–desorption analysis and scanning electron microscopy. The microstructures of the dual pore system of aerogels were quantitatively characterized using image analysis methods. The gas permeability was measured and discussed with respect to the well-known model of Carman–Kozeny for open porous materials. The gas permeability values implied that the kind of the macropore channel’s size, shape, their connectivity through the neck parts and the mesoporous structures on the cell walls are significantly controlling the flow resistance of air. Adaption of this new design route for cellulose-based aerogels can be suitable for advanced filters/membranes production and also biological or catalytic supporting materials since the emulsion template method allows the tailoring of the gas permeability while the nanopores of the cell walls can act simultaneously as absorbers.

scholarly journals Nanoscale pore characteristics and fractal characteristics of organic-rich shale: An example from the lower Cambrian Niutitang Formation in the Fenggang block in northern Guizhou Province, South China

2018 ◽  
Vol 37 (1) ◽  
pp. 273-295 ◽  
Author(s):  
Yang Gu ◽  
Wenlong Ding ◽  
Min Yin ◽  
Baocheng Jiao ◽  
Siyu Shi ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Pore Structure ◽  
Carbon Content ◽  
South China ◽  
Fractal Dimensions ◽  
Nitrogen Adsorption ◽  
Organic Carbon Content ◽  
Structure Parameters ◽  
Pore Characteristics ◽  
Fractal Characteristics

Organic-rich marine shale in South China has great potential for gas generation, and the pore structure has a considerable influence on the enrichment of shale gas. The nanoscale pore characteristics and fractal characteristics of the Niutitang shales in the Fenggang block were studied by means of methane adsorption and low-pressure nitrogen adsorption experiments, porosity and permeability tests, X-ray diffraction analyses, organic geochemical analyses, and field emission scanning electron microscopy. The fractal geometry of the pore structure was assessed, and the factors influencing the pore structure were determined. We used a fractal Frenkel–Halsey–Hill-based method to obtain the fractal dimensions D1 and D2 by nitrogen adsorption at relative pressures of 0–0.5 and 0.5–1, respectively. The relationships between the shale pore structure parameters and the fractal dimensions, the mineral composition, the total organic carbon content, and the pore structure parameters of shale are discussed. In addition, the significance of D1 and D2 and the implications of the fractal dimension for the adsorption capacity of shale are investigated. The results show that the two fractal dimensions are positively correlated with total organic carbon content and specific surface area, negatively correlated with quartz content and average pore diameter, but have a weak relationship with clay mineral content and total pore volume. The Niutitang shale samples are dominated by mesopores, and the pore structure is complicated. The results presented here indicate that fractal analyses represent an effective method of characterizing the complexity of pore structure.

Comparative analysis of pore structure parameters of coal by using low pressure argon and nitrogen adsorption

Fuel ◽  
2022 ◽  
Vol 309 ◽  
pp. 122120
Author(s):  
Zhenyang Wang ◽  
Yuanping Cheng ◽  
Gang Wang ◽  
Guanhua Ni ◽  
Liang Wang
Keyword(s):  
Comparative Analysis ◽  
Pore Structure ◽  
Nitrogen Adsorption ◽  
Low Pressure ◽  
Structure Parameters

scholarly journals The impact of changes in pore structure on the compressive strength of sulphoaluminate cement concrete at high temperature

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
J.J.K. Tchekwagep ◽  
P. Zhao ◽  
S. Wang ◽  
S. Huang ◽  
X. Cheng
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Elevated Temperatures ◽  
Nitrogen Adsorption ◽  
Cement Concrete ◽  
Constant Weight ◽  
Sulphoaluminate Cement ◽  
Structure Changes ◽  
The Impact ◽  
The Relationship

Abstract The internal pore structure of sulphoaluminate cement concrete (SACC) significantly affects its mechanical properties. The main purpose of this study was to establish the relationship between pore structure changes and compressive strength after exposure to elevated temperatures. SACC samples that had been cured for 12 months were dried to a constant weight and then exposed to different temperatures (100 °C, 200 °C and 300 °C), after which the compressive strength and pore structure were measured. The pore structure of SACC was quantitatively described by mercury intrusion porosimetry (MIP) and nitrogen adsorption results. The results showed that with increased temperature, the porosity of the SACC samples also increased and the pore structure was gradually destroyed. Moreover, the SACC’s compressive strength gradually decreased with increasing temperature. The relationship between compressive strength and porosity was in close agreement with the compressive strength–porosity equation proposed by Schiller. Therefore, after extensive exposure to elevated temperature, the changes in SACC’s compressive strength can be quantitatively described by the Schiller equation.

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

Cognitive Impact of Cerebellar Damage: Is There a Future for Cognitive Rehabilitation?

2018 ◽  
Vol 17 (3) ◽  
pp. 199-206 ◽  
Author(s):  
Kim van Dun ◽  
Frank V. Overwalle ◽  
Mario Manto ◽  
Peter Marien
Keyword(s):  
Affective Disorders ◽  
Cognitive Rehabilitation ◽  
Therapeutic Interventions ◽  
Posterior Fossa Surgery ◽  
Daily Life Activities ◽  
Wide Range ◽  
Affective Deficits ◽  
Cerebellar Injury ◽  
Cognitive Therapies ◽  
The Impact

Background & Objective: During the past 3 decades, numerous neurophysiological, neuroimaging, experimental and clinical studies have evidenced a crucial role for the cerebellum in cognitive, affective and behavioral functions. As a result of the acknowledged modulatory role of the cerebellum upon remote structures such as the cerebral cortex, cerebellar injury may give rise to a constellation of behavioral, affective and cognitive symptoms (Schmahmann's Syndrome). In sharp contrast to the wide range of therapeutic interventions to treat cognitive and affective disorders following cerebral cortical lesions and despite the consequences of Schmahmann’s syndrome upon daily life activities, the literature is surprisingly only scantly documented with studies investigating the impact of cognitive therapies on cerebellar induced cognitive and affective disorders. This survey aims to present an overview of the therapeutic interventions available in the literature as a possible treatment for Schmahmann’s Syndrome after cerebellar injury, after posterior fossa surgery in children, and in children with neurodevelopmental disorders. Although systematical studies are clearly warranted, available evidence suggests that cerebellar-induced cognitive and affective disorders should be treated in a specific way. Approaches where the patients are explicitly made aware of their deficits and are considered to act as an “external cerebellum” are the most promising. Conclusion: The study of the anatomical connectivity of the cerebellar microcomplexes involved in cognitive/affective deficits is likely to play a major-role in the future.

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