Electrostatic precipitator is the most efficient device used for the removal of fly ash particles from the flue gases produced by coal-fired boilers in power plants. However, the fractional ...collection efficiency of electrostatic precipitators steeply decreases for particles smaller than 1 μm, and particles in the size range of 200–500 nm are removed with lower collection efficiency than those outside this range. These particles are dangerous to humans and have detrimental environmental effects, so there is a need for novel more efficient technologies for their control. One of the answers to this challenge is the two-stage electrostatic precipitator, in which the electrostatic charging and precipitation processes have been separated. The PM2.5 particles (of a size < 2.5 μm) are electrically charged in a separate device (precharger) to a maximal possible electric charge, and then precipitated in a parallel plate collector, free of corona discharge. The electric field in the collection stage can be higher than in an electrostatic precipitator due to the lack of sharp discharge points. A higher electric field allows an increase of the collection efficiency for PM2.5 particles. Another solution is the agglomeration of submicron particles to form larger particles before their precipitation by a parallel-plate collector, conventional electrostatic precipitator or any other gas cleaning device. In some of the reviewed devices, both of these processes were combined in a single device that allowed further increases in the collection efficiency for submicron particles. Devices of this type have been tested in a lab- or semi-industrial scale for the removal of PM2.5 particles from flue gases or diesel engine exhausts. In this paper, various constructions of two-stage electrostatic precipitators, comprising a precharger and/or agglomerator in the first stage, and an electrostatic collector in the second stage, have been reviewed. Some of these devices were able to increase the mass collection efficiency above 95% for PM2.5 particles.
•Electrostatic hybrid systems for the removal PM2.5 particles have been reviewed.•Electrostatic hybrid systems appear to be versatile tools for flue gas cleaning.•There is an increasing demand from ...energy sector for hybrid systems.
The removal of submicron and nanoparticles from flue gases emitted by coal fired boilers is the subject of extensive studies in recent years. Electrostatic precipitators and fibrous filters are the most commonly used gas-cleaning devices for the removal of these particles in power plants and industry. However, the collection efficiency of electrostatic precipitators decreases for particles smaller than 1 µm. Fibrous filters provide higher filtration efficiency for particles of this size, but the pressure drop is higher, and additional energy is needed to supply the outlet fan. Recently, special attention of engineers has been given to hybrid constructions, which apply electrostatic fields and forces in order to improve the performances of bag filters. There are three types of such solutions, which have been investigated in the literature: (1) electrically energized filter, in which fibres of the filter are energized by an electric field; (2) hybrid electrostatic filter, which applies electrostatic charging of particles before their filtration by bag filter; and (3) hybrid electrostatic precipitator, which uses a conventional electrostatic precipitator for the removal of coarse particles, and a subsequent bag filter for the removal of fine particles leaving the precipitator. All of these constructions allow the collection efficiency for PM2.5 particles to be increased and the pressure drop across the bag filter to be reduced. In this paper, various hybrid electrostatic filtration systems have been reviewed and their performances compared with respect to the collection efficiency, pressure drop and dust cake dislodging.
•Two-stage ESP comprising of agglomerator and ESP was investigated.•Collection efficiency for PM1 and PM2.5 was higher than for conventional ESP.•Mass collection efficiency for fly ash PM2.5 and PM1 ...particles was higher than 95%.
Semi industrial-scale, two-stage electrostatic precipitation system comprised of unipolar electrostatic agglomerator and electrostatic precipitator was investigated in this paper. In this type of agglomerator, the process of particle charging and their agglomeration is accomplished in the same device. The particles are charged by ion current in alternating electric field, and agglomerated due to their oscillatory motion in this field, perpendicular to the gas flow. The charged and agglomerated particles are collected in the next stage, which is a conventional electrostatic precipitator with spiked wire discharge electrodes and collection electrodes of the sigma type. Collection efficiency of this system was measured for different gas temperatures, different fly ash concentrations and for various magnitudes of AC voltage applied to the agglomerator.
Two-stage electrostatic precipitator allows obtaining higher fractional collection efficiency for PM1 and PM2.5 particles than a one-stage electrostatic precipitator. In this type of two-stage electrostatic precipitator with an agglomerator, the number collection efficiency for fly ash particles in PM10, PM2.5 and PM1 size ranges was about 96%, 96% and 94%, respectively, and mass collection efficiency in same size ranges was 98%, 97% and 95%, respectively.
The collection efficiency of lab-scale, two-stage electrostatic precipitator comprising a dual-corona particle precharger and parallel-plate particle collector for the removal of PM2.5 particles was ...investigated in this paper. In the precharger stage, particles conveyed by a gas were electrically charged by ionic current in corona discharge, and in the collection stage, the charged particles were removed from the gas by DC electric field between two parallel-plate electrodes. For the same electrode geometry, the precharger can operate as unipolar or bipolar precharger and/or agglomerator, depending on the mode of electrode supply. The collection efficiency of the system was determined for various modes of precharger electrodes supply with DC or AC voltage. The measurements have shown that number collection efficiency for PM2.5 particles was higher than 80% for the system with dual-corona unipolar precharger supplied with AC voltage and >90% for supply with DC voltage of negative polarity. For the same system, mass collection efficiency was >90% and >96% for PM2.5 particles when precharger was supplied with AC and DC voltages, respectively.
The Wnt signalling pathway is a critical regulator of bone mass and quality. Several heterozygous mutations in the LRP5 gene, a Wnt co-receptor, causing high bone mass (LRP5-HBM) have been described ...to date. The pathogenic mechanism is thought to be a gain-of-function caused by impaired inhibition of the canonical Wnt signalling pathway, thereby leading to increased bone formation.
We report the cases of two affected family members, a 53-year-old mother and her 23-year-old daughter, with high bone mass (T-scores mother: lumbar spine 11.4, femoral neck 10.5; T-scores daughter: lumbar spine 5.4, femoral neck 8.7), increased calvarial thickness, and thickened cortices of the long bones but no history of fractures. Whereas the mother did not show any indications of the mutation, the daughter suffered from congenital hearing impairment resulting in cochlear implantation, recurrent facial palsy, and migraine. In addition, she had stenosis of the foramen magnum. In both individuals, we detected a novel heterozygous duplication of six basepairs in the LRP5 gene, resulting in an insertion of two amino acids, very likely associated with a gain-of-function. When the daughter had part of the occipital bone surgically removed, the bone sample was used for the visualization of bone lamellar structure and bone cells as well as the measurement of bone mineralization density distribution (BMDD). The bone sample revealed two distinctly different regions: an intra-cortical region with osteonal remodeling, typical osteonal lamellar orientation, associated with relatively higher heterogeneity of bone matrix mineralization, and another periosteal region devoid of bone remodeling, with parallel bone lamellae and lower heterogeneity of mineralization.
In conclusion, we present data on bone tissue and material level from an LRP5-HBM patient with a novel mutation in the LRP5 gene. Our findings indicate normal morphology of osteoclasts and osteoblasts as well as normal mineralization in skull bone in LRP5-HBM.
•We present two affected family members with a novel mutation in the LRP5 gene: c.509_514dupGGGGTG (p.G171_E172insGG).•This mutation is associated with increased bone mineral density (T-score +11.4 at lumbar spine in one patient e.g.).•Both patients have increased calvarial thickness and thickened cortices of the long bones but no history of fractures.•A skull bone sample from one patient revealed normal morphology of osteoclasts and osteoblasts and normal mineralization.
•Heavy metals partitioning between consecutive stages of ESP has been compared for different coals.•The concentration of heavy metals in fly ashes from Polish coals is at a level similar to mean ...values from other coals.•The concentration of heavy metals increased in fly ash from the consecutive fields of ESP.•The concentration of heavy metals correlates with decreasing mean size of precipitated particles.•Heavy metals are mainly retained in the finest particles of fly ash due to their deposition on the particle surface.
The paper presents experimental studies of heavy metals partitioning in fly ash particles after combustion of various types of coal (lignite, sub-bituminous, bituminous, and anthracite) between different fields of electrostatic precipitator. The concentration of the following heavy metals has been measured: Ba, Sr, Zn, Cu, Ni, Cr, As, Co, Pb. The results show that the concentration of heavy metals is higher in small particles (<1μm) than in larger ones that correlates with consecutive fields of electrostatic precipitator. This relation is independent of the type of combusted coal, although differences in the values of concentrations of individual elements exist. Better knowledge on heavy metal partitioning in the combustion-precipitation system is needed for the development of emission control devices of higher efficiency, such as electrostatic agglomerators or hybrid filters, particularly for PM1 particles. The results of these investigations can also be helpful in the designing of novel physical and chemical processes for recovery selected trace elements from fly ash, for their further utilization.
Automated volumetry of the hippocampus is considered useful to assist the diagnosis of hippocampal sclerosis in temporal lobe epilepsy. However, voxel-based morphometry is rarely used for individual ...subjects because of high rates of false-positives. We investigated whether an approach with high dimensional warping to the template and nonparametric statistics would be useful to detect hippocampal atrophy in patients with hippocampal sclerosis.
We performed single-subject voxel-based morphometry with nonparametric statistics within the framework of Statistical Parametric Mapping to compare MRI from 26 well-characterized patients with temporal lobe epilepsy individually against a group of 110 healthy controls. The following statistical threshold was used:
< .05 corrected for multiple comparisons with family-wise error over the region of interest right and left hippocampus.
The sensitivity for the detection of atrophy related to hippocampal sclerosis was 0.92 (95% CI, 0.67-0.99) for the right hippocampus and 0.60 (0.31-0.83) for the left, and the specificity for volume changes was 0.98 (0.93-0.99). All clusters of decreased hippocampal volumes were correctly lateralized to the seizure focus. Hippocampal volume decrease was in accordance with neuronal cell loss on histology reports.
Nonparametric voxel-based morphometry is sensitive and specific for hippocampal atrophy in patients with mesial temporal lobe epilepsy and may be useful in clinical practice.
Minichromosome maintenance (MCM) proteins are key elements that function as a part of the pre-replication complex to initiate DNA replication in eukaryotes. Consistent with their roles in initiating ...DNA replication, overexpression of MCM family members has been observed in several malignancies. Through bioinformatic analysis of The Cancer Genome Atlas's data on glioblastoma multiforme (GBM), we found that the genomic region containing MCM7 gene was amplified in more than 80% of the present cases. To validate this finding and to identify the possible contribution of the remaining members of the MCM family to GBM progression, we used quantitative real-time PCR to analyze the gene expression profiles of all MCM family members in Grade IV (GBM) tissue samples and observed a significant upregulation in GBM samples compared with normal white matter tissues. In addition, we compared the observed gene expression profiles with those of Grade II and Grade III astrocytoma samples and determined that the observed upregulation was restricted and specific to Grade IV. MCM7 was the most upregulated gene in the gene set we analyzed, and therefore we wanted to identify the role of MCM7 in GBM progression. We determined that siRNA-mediated knockdown of MCM7 expression reduced GBM cell proliferation and also inhibited tumor growth in both xenograft and orthotopic mouse models of GBM. Taken together, our data suggest that MCM7 can be a potential prognostic marker and a novel therapeutic target in GBM therapy.
The paper presents comparison of the collection efficiency of semi-industrial, two-field electrostatic precipitator and two-stage electrostatic precipitator comprising an electrostatic agglomerator. ...The two-stage electrostatic precipitator was converted from two-field electrostatic precipitator, in which the first field was replaced by unipolar electrostatic agglomerator. The investigated electrostatic precipitator was of parallel-plate type, with spiked-wire discharge electrode between sigma type collection electrodes. In the unipolar agglomerator used in this system, the particles were charged by ion current and forced to oscillate by alternating electric field. The oscillatory motion of particles perpendicular to the gas flow causes the collision between particles and deposition of small particles onto the larger ones. The agglomerated particles were next collected by one-field electrostatic precipitator.
The collection efficiency of two-stage electrostatic precipitator for PM2.5 and PM1 particles was 99.1% and 98.8%, compared to 99% and 98.1% of two-field electrostatic precipitator, respectively. The most important result of this research is that the replacement of the first field of electrostatic precipitator by an electrostatic agglomerator does not change the overall collection efficiency of the system but the power consumption of electrostatic agglomerator can be 10–50 times lower than by the replaced field of electrostatic precipitator.
•Collection efficiency of two-field and two-stage ESPs have been compared.•Replacement of 1st field in two-field ESP with agglomerator does not decrease the collection efficiency.•Mass collection efficiency of both systems for PM2.5 particles was at least 99%.•Energy consumption by agglomerator was an order of magnitude lower than by replaced field of ESP.
Temporal lobe epilepsy, structural or nonlesional, may negatively affect language function. However, little is known about the lesion-specific influence on language networks. We hypothesized that ...different epileptogenic lesions are related to distinct alterations in the functional language connectome detected by fMRI.
One hundred one patients with epilepsy due to mesiotemporal sclerosis (21 left, 22 right), low-grade mesiotemporal tumors (12 left), or nonlesional temporal lobe epilepsy (22 left, 24 right) and 22 healthy subjects performed 3T task-based language fMRI. Task-based activation maps (laterality indices) and functional connectivity analysis (global and connectivity strengths between language areas) were correlated with language scores.
Laterality indices based on fMRI activation maps failed to discriminate among patient groups. Functional connectivity analysis revealed the most extended language network alterations in left mesiotemporal sclerosis (involving the left temporal pole, left inferior frontal gyrus, and bilateral premotor areas). The other patient groups showed less extended but also predominantly ipsilesional network changes compared with healthy controls. Left-to-right hippocampal connectivity strength correlated positively with naming function (
= .01), and connectivity strength between the left Wernicke area and the left hippocampus was linked to verbal fluency scores (
= .01) across all groups.
Different pathologies underlying temporal lobe epilepsy are related to distinct alterations of the functional language connectome visualized by fMRI functional connectivity analysis. Network analysis allows new insights into language organization and provides possible imaging biomarkers for language function. These imaging findings emphasize the importance of a personalized treatment strategy in patients with epilepsy.
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