Occurrence Of Erosion Research Articles

Bilateral vocal cord paralysis caused by accidental button battery ingestion in children: A case report and literature review.

Button battery ingestion in pediatric populations is a common occurrence with severe sequelae. Multiple case reports have established the occurrence of death, fistula formation, mucosal erosion, esophageal perforation, and bleeding post-ingestion of button batteries. However, there is a gap in the literature on the occurrence of bilateral vocal cord paralysis post-lithium battery ingestion. We present a case in which a 12-month-old male developed bilateral vocal cord paralysis following ingestion of a button battery. We compare our case to eleven other reports that exist in the literature based on age, sex, time until removal, clinical presentation, day upon which vocal cord paralysis developed, anatomic location, and post-operative course. We conclude that bilateral vocal cord paralysis is a time-sensitive complication which requires prompt diagnosis. Any child with stridor following button battery ingestion should undergo consultation with pediatric otolaryngology immediately. In addition, long-term follow-up is necessary to evaluate return of normal vocal cord function.

Autonomic dystonia syndrome in conditions of failure of the Bauhinia valve and after its surgical correction as a possible link in the etiopathogenesis of peptic ulcer disease

The classic works of I.P. Pavlov shows strong communication mechanisms between the two most important life-supporting systems of the body - the nervous and the digestive. The role of the autonomic nervous system (ANS) in the occurrence of acute gastroduodenal erosions and ulcers has been proven [1]. The flow of sympathetic impulses causes an excessive release of mediators (catecholamines), which leads to disruption of tissue trophism. An important role in ulceration belongs to the parasympathetic nervous system.

Expansion of CD4+CD8+ double-positive T cells in rheumatoid arthritis patients is associated with erosive disease.

CD4+CD8+ double-positive (DP) T cells are expanded in the peripheral blood of a subset of patients with RA. This study examines the clinical significance of DP T cells in RA. In 70 RA patients, DP T cells were measured by flow cytometry. Clinical data were obtained, and hand and feet radiographs were scored according to the Sharp/van der Heijde (SvdH) method. The association between DP T cell frequency and erosive joint destruction was analysed by correlation and multiple logistic regression analysis. Nineteen RA patients (27.1%) displayed increased DP T cell frequencies, which correlated with age (r = 0.288, P =0.016). Expansion of DP T cells was associated with the occurrence of erosions (94,7% vs 43,1%, P <0.001), with a higher SvdH joint damage score (24.5 vs 6, P =0.008) and with more frequent use of biologic or targeted-synthetic DMARDs (68.4% vs 38%, P =0.02). In patients with non-erosive disease, DP T cell frequencies correlated with the joint space narrowing score (n = 28, r = 0.44, P =0.02). Logistic regression revealed DP T cells to be associated with erosive disease (OR 1.90, P <0.05). Expansion of DP T cells is associated with joint damage and frequent escalation of therapy, possibly suggesting a contribution to more severe RA.

Ultrasound in osteoarthritis of the hand: a comparison to computed tomography and histology.

To compare structural findings between US, micro-CT (µCT) and histology in people with OA of the hands. We analysed DIP and PIP joints of 31 fingers from 15 dissecting-room cadavers with OA of the hands. The occurrence of bone erosions and osteophytes were recorded by US, µCT and histology at 16 regions for each joint and compared for each method. In total, US (n = 558, 56.2% of 992 examined regions) and µCT (n = 493, 49.7%) detected a higher frequency of osteophytes at PIP and DIP joints than histology (n = 161, 23.4% of 689 histological examined regions; P = 0.01). We found a comparable number of erosions with each method [US, n = 52 (5.2%); µCT, n = 43 (4.3%); histology, n = 35 (5.2%)]. Both imaging techniques correlated moderately with each other regarding the detection of osteophytes (r = 0.54, P = 0.002) and erosions (r = 0.43, P = 0.017). Neither US nor µCT correlated with histology regarding erosions or osteophytes. With histology as the reference, US had a sensitivity of 80% and a specificity of 32% to detect osteophytes, whereas µCT had a sensitivity of 73% and a specificity of 27%. For erosions, sensitivities (US 10% and µCT 6%, respectively) were much lower. Microscopically, erosions contained fibrous myxoid tissue extending from subcortical cavities through the breach of cortical bone. The ability of US to identify osteophytes was comparable to that of µCT, yielding a good sensitivity when histology was used as the gold standard. The sensitivity of US and µCT to detecting erosions was low compared with histology.

Erosion prediction of several land utilization in Dadakitan Village, Baolan sub-district, Toli-Toli Regency

This study aims to determine the amount of soil erosion and the danger index of erosion in several lands uses in Dadakitan Village, Baolan Sub-District, Toli-Toli Regency. In this study, slope class maps and land use maps were overlaid, in order to obtain six land uses include the use of paddy fields, coconut plantation, cocoa plantation, cloves plantation, and forests. Erosion prediction was carried out for all land uses. The survey was then carried out on six land uses to observe the slope and the dominant vegetation. Soil samples were taken deliberately for each land use; three samples for each sample of intact soil and disturbed soil. Erosion prediction analysis was using the USLE (Universal Soil Loss Equation). The results showed that the erosion hazard index occurred in Dadakitan Village was classified as low, high, and very high. Low erosion occurred in paddy fields, coconut plantation, and cocoa plantation. In contrast, high levels of erosion occurred on clove plantation, and very high erosion level occurred on forest lands. The dominant factors affecting the occurrence of erosion in this area were soil erodibility, topography, plant management, and conservation measures.

Condition of hard tissues of teeth and oral fluid in athletes-swimmers

Objective: to determine the state of dental hard tissues and saliva parameters changing in competitive swimmers, before and after a 2­hour training session in the chlorinated water swimming pool.Materials and methods: saliva parameters of competitive swimmers trained in the sport club “Grifon”, city of St. Petersburg, Russia (n = 21), age of participants 18.1 ± 3.5 years, qualifications (1 category­Master of Sports) and track and field athletes of the sports schools “Nevsky district” and “Orlyonok”, city of St. Petersburg, Russia (n = 18), age of participants 18.80 ± 4.54 years, qualifications (1 category — Master of Sports), have been analyzed by various tests include a study of calcium (Ca), phosphorus (P), fluorine (F) levels, and pH before and after training sessions. All athletes in the experimental and control groups have passed an examination by dentist, including: examination of the oral cavity with the determination of the KPU index (the sum of carious, filled and removed permanent teeth in the subject), examination of the most common places of occurrence of dental enamel erosion (medical binoculars) and filling out specially designed questionnaires.Results: there was a tendency to decrease of the average saliva pH in competitive swimmers’ group after a training session, varying from 6.9 ± 0.1 (before training) to 6.5 ± 0.1 (after training) (p &gt; 0.05). In track and field athletes, saliva pH did not change significantly (7.1 ± 0.2 before training and 7.0 ± 0.1 after training) (p &lt; 0.05). The competitive swimmers showed a statistically significant increase in Calcium (Ca) levels (1.25 ± 0.15 mmol/L before exercise and 1.56 ± 0.11 mmol/L after exercise) and Fluorine (F) (0.0010 ± 0.0003 mmol / L before exercise and 0.0090 ± 0.0004 mmol / L after training session) in saliva. The Phosphorus (P) level in saliva was significantly reduced after the training session (from 6.09 ± 0.39 to 3.89 ± 0.46 mmol / L) (p &gt; 0.05). In track and field athletes, there were no significant changes in Ca, F and P levels before and after a training session. As a result of the dentist’s examination, competitive swimmers were found to have 3 athletes (14.3 %) with lesions of the teeth enamel, corresponding to dental erosion and caused by localized demineralization. In the control group of athletes, no such pathologies were revealed.Conclusion: discovered saliva parameters changing in competitive swimmers (decrease in free salivation, pH level, and increase in the level of Ca and F in saliva) can contribute to the demineralization of tooth enamel. Timely and controlled use of fluorides (as part of mouth rinses, application gels, fluoride varnishes), regular preventive dental examinations, in order to prevent the loss of mineral composition of the teeth when swimming in chlorinated pools, will minimize the risk of staining and dental enamel erosions.

Estimating temporal and spatial changes in soil organic carbon stocks and its controlling factors in moraine landscapes in Denmark

Assessing temporal changes in soil organic carbon (SOC) stocks is important when evaluating the SOC sequestration potential of soil management strategies. The monitoring of SOC stocks is challenging, particularly in eroding landscapes where erosion-induced changes in SOC stocks are superimposed on changes related to management. In this study we focused on the spatio-temporal variations of SOC in eroding cropland soils of the northeast of thepeninsulaofJutland (Denmark) at field scale. We examined soil redistribution processes as control factors of SOC changes (ΔSOC) during a 16-year period by using soil data (both spatial and with depth) collected over two distinct periods in 1998 and 2014. Topographic changes between 1998 and 2014, derived from high resolution digital elevation models, were used to identify eroded, stable and depositional areas within the field. There was a predominance of soil loss, with 44% of the sampling points corresponding to eroded sites and 28% to depositional sites, while the remainder was considered as stable soils. Substantial erosion was detected and at the field scale, soil deposition equalled (29.7 ± 17.5 Mg ha−1 y−1) while soil erosion rates were lower with a mean of 25.8 ± 12.9 Mg ha−1 y−1. Comparing SOC stocks over the 16 year-period showed that on average, and when considering the whole soil profile, SOC contents and stocks were stable. However, this masked substantial dynamics that were related to erosion processes. Despite the occurrence of net soil erosion at the field scale, there was an overall increase in SOC storage of 1.88 Mg ha (SOC2014:SOC1998 ratio ≥ 1). Losses of SOC in topsoils (6%) and SOC gain (34%) in soil layers below the plough depth (25–45 cm) could be related to soil disturbances caused by tillage and the significant downward transport of topsoil SOC within the soil profile. Soil disturbances caused by tillage practices (i.e. soil management) and SOC transportation from topsoil to subsoil may be responsible for the downward movement of organic carbon and consequent SOC accumulation in subsoils. In addition the successive deposition and deep burial of SOC rich topsoils at depositional sites due to the effect of topography and slope position favours the enrichment of SOC in subsoils. It was estimated that as much as 11% of the sampling points changed from eroded to depositional sites and 15% of them varied from erosion to stable sites, and this might have favoured SOC accumulation. These results clearly show that understanding and quantifying soil redistribution processes is key to assess SOC temporal changes in agricultural soils. This is important to develop site-specific management strategies that improve SOC sequestration at local scale.

Effects of bedrock erosion by tillage on architectures and hydraulic properties of soil and near-surface bedrock

Tillage erosion provides an opportunity for the occurrence of bedrock erosion in hilly croplands with shallow soil layer, influencing the hillslope architecture to some extent. In this study, tillage simulation, hydraulic tests and dye-staining tracing were performed to identify the variation in architectures and relevant hydraulic properties of the soil and near-surface bedrock caused by tillage-induced bedrock erosion. Results show that tillage-induced bedrock erosion played an important role in shaping the rock fragment architecture. Under the condition of no-soil cover, the coarse rock fragment content increased from 29.8% to 38.2% when tillage depth increased from 2 to 6 cm. The field-saturated hydraulic conductivity (Kfs) ranged from 18.63 to 23.78 m d−1 by the Guelph method and 24.26 to 98.46 m d−1 by the single ring (SR) method, but effects of tillage depth on Kfs did not show a clear pattern. Under the condition of overlying soil layer, the contents of medium, coarse and total rock fragments in soil increased significantly with tillage depth (P < 0.05). Correspondingly, the Kfs for the soil increased significantly with tillage depth (P < 0.05), implying that the higher content of rock fragments due to the greater tillage depth created the more water flow channels. With respect to the near-surface bedrock, the results of dye-staining tracing show that bedrock fragmentation by tillage tended to promote the development of fracture-preferential flow. The infiltration data derived from the SR method show that the Kfs increased by 33.3% to 50.0% after bedrock fragmentation by tillage compared with that for the control treatment, corresponding to the results of dye-staining tracing. These results suggest that tillage-induced bedrock erosion exerts positive effects on infiltration in the soil and near-surface bedrock by increasing preferential channels.

Applying different resampling strategies in machine learning models to predict head-cut gully erosion susceptibility

Gully erosion is one of the advanced forms of water erosion. Identifying the effective factors and gully erosion predicting is one of the important tools to control and manage such phenomenon. The main purpose of this study is to evaluate the effect of four different resampling algorithms including cross-validation (5-fold and 10-fold) and bootstrapping (Bootstrap and Optimism bootstrap) on boosted regression tree (BRT), support vector machine (SVM), and random forest (RF) models in spatial modeling and evaluation of head-cut gully erosion in Konduran watershed. For this purpose, based on an extensive field survey, the points of the head-cut of the gully erosion were identified first, and a map of the distribution of head-cut gully erosion in the study area was prepared. Then 18 variable identify and prepare as factors affecting the occurrence of head-cut gully erosion. To assess the efficiency of the models, receiver operating characteristics (ROC) and area under the curve (AUC) were used. <Through the assessment result we indicate that…>The results of the assessment indicated that the use of resampling algorithms increases the efficiency of the models. The integrated optimism-bootstrap-BRT, optimism-bootstrap-SVM, and Optimism-Bootstrap-RF models with AUC 0.85, 0.823 and 0.89 respectively, outperformed the cross-validation 5fold (BRT, SVM, RF), Cross-validation 10fold (BRT, SVM, RF) and Bootstrap (BRT, SVM, RF) integrated algorithms.

Impact of land-use land cover dynamics on runoff in Panchnoi River basin, North East India

Abstract Alteration of land-use land cover pattern causes severe consequences on the hydrological system by modifying the rainfall-runoff pattern in a region. The study aimed to investigate the impact of land-use land-cover dynamics on runoff generation in different geomorphic divisions of Panchnoi River basin. The study used the Soil Conservation Service-Curve Number method to estimate runoff generation in the Panchnoi River basin in a GIS platform. This study observed that the conversion of the land-use pattern in the geomorphic zones significantly enhances runoff. The Piedmont experience highest land-use change, where 64.17 km2 forest cover lost to cropland and built-up lands, leads to a notable increase in runoff generation, i.e. from 1 076 mm (52.82% of rainfall) in 1990 to 1 467 mm (70.46% of rainfall) in 2015. The Flood plain and New alluvial plain generates high runoff in the basin as it mostly occupied by human-induced land-uses, i.e. 1 444 mm (72.72% of rainfall) and 1 360 mm (71.70% of rainfall) respectively in 1990, which increase to 1588 mm (79.20%) and 1507 mm (78.69%) runoff respectively in 2015, due to alteration of cropland to built-up lands. In the Old alluvial plain, a marginal land-use change observed resulted in moderate growth in runoff from 1 272 mm (62.35%) to 1 404 mm (66.79%). The study indicates land-use land-cover change invokes to increase runoff generation can give rise severe environmental and economic problems in the river basin, through the occurrence of flashflood and soil erosion. Highlights for public administration, management and planning: • Evaluation of the impact of land-use land cover dynamics on runoff is essential for containing flash flood and water resource management on a basin scale. • Alteration of natural land covers has severe implications in the form of flood, soil erosion, and loss of biodiversity. • Enhanced runoff due to land-use dynamics reduces groundwater recharge rate that may cause drinking water scarcity in the dry season shortly.

Relation between Childhood Asthma and Dental Erosion in Al-Kharj Region of Saudi Arabia: A Cross-Sectional Study.

Background:Asthma is a long-lasting disease that affects large number of the society and could impact on the oral health leading to increase in the needs of prevention and treatment. Currently, the prevalence of childhood asthma in Saudi Arabia is ranging from 9% to 33%.Objective:the objective was to evaluate dental erosion in control children and those with asthma.Materials and Methods:This was a cross-sectional study, with a sample of 100 children aged 3–12 years. Equally distribution of subjects was between the asthmatic and non-asthmatic group, at Prince Sattam Bin Abdulaziz University Dental Clinics, Alkharj, Saudi Arabia. The assessment consisted of an oral examination assessing erosive wear according to the American Academy of Pediatrics 2018 guidelines and a questionnaire to the parents/guardians addressing the background details and information about the child asthma.Results:Among 12 (24%) asthmatic children and 9 (18%) non-asthmatic children had dental erosion. In the adjusted analysis, no association was found between asthma and erosion. It has been shown that oral hygiene may have an effect occurrence or severity of erosion; brushing teeth once or more per day appeared to have less incidence of dental erosion compared with those not brushing their teeth regularly.Conclusions:This article provided no additional data than that given earlier, where no correlation was observed between asthma and dental erosion in children aged from 3 to 12 years.

Soil and water losses along the cultivation cycle of onion in Irati, Brazil

Onion is one of the most important vegetables grown in southern Brazil. However, despite its profitability, little is known about its response to soil erosion throughout its productive cycle divided into 5 stages: S1 (germination), S2 (formation of leaves and roots), S3 (bulbification), S4 (snap) and S5 (harvesting). With the aim of providing knowledge in this matter we have analyzed the intra-cycle dynamics of some parameters such as bulk density (BD), porosity, soil penetration resistance (SPR), and soil and water losses. To do that we have assessed these parameters in 40 random points and at different depths in a representative farm of 3 ha located in the municipality of Irati (Paraná, Brazil). BD was quantified by using the core method, porosity after particle density quantification by the volumetric balloon method, and SPR by impact penetrometer. Soil and water losses were estimated after carrying out 30 rainfall simulations (6 per crop stage). The results showed that bulk density increased progressively and continuously from 1.06 to 1.36 g cm−3. This greater compaction was also observed in the values of SPR that increased from 2.0 to above 3.0 MPa at the end of the cycle. Regarding soil erosion the highest rates were recorded at S4 when onions are snapped (431.0 g m−2). We conclude the occurrence of runoff and soil erosion is a consequence of the increase in soil compaction throughout the cycle provoked by the repeated pass of heavy machinery and workers to apply herbicides and fertilizers. Since soil erosion rates found are relatively high (1437.1 g m−2 y−1) we suggest the progressive implementation of conservationist practices to guarantee its sustainability.

Morphological Changes along the shoreline of the arcuate Niger Delta from Parts of Delta State to Akwa Ibom State between 1986 and 2016

This study analyzes the morphological changes occurring at the arcuate Niger Delta shoreline by identifying factors that contribute to erosion-induced shoreline changes and the rate of shoreline change from Forcados (Delta State) to Ibeno (Akwa Ibom State). Shoreline changes were compared from 1986 to 2016 as well as among western, central and eastern sections of the arcuate Niger Delta using Landsat satellite imagery within Geographic Information System (GIS) environment. In the assessment of the entire shoreline, accretion was 5,477.814Ha (1.2%) in 1986 and 19181.53Ha (4.1%) in 2016. For erosion, it was 48,400.03 (10.3%) in 1986 and 68398.84Ha (14.5%) in 2016. This indicates that accretion increased by 2.91% and erosion also increased by 4.25% in 30 years. The major accretion was detected within Brass (Bayelsa State), Bonny (River State), Andoni (River State) and Ibeno (Akwa Ibom State). Forcados South Point (Delta State), Sombreiro River mouths and eastern Obolo recorded the highest level of shoreline erosion. For land use/land cover (LULC), vegetation was 27.4% in 1986 but reduced to 22.9% in 2016; a change I attributed to massive conversion of vegetative cover for anthropogenic activities in the area. The study concluded that major erosion cases are due to the changing climate and the velocity of flow of major estuaries into the ocean. The activities that contribute to the shoreline change aside the challenging natural factors are sand mining, hard and engineered structures on the shore and other commercial and social activities. The occurrences of shoreline erosion have contributed to the degradation of these coastal ecosystems, loss of human settlements and livelihood. It is therefore essential to implement precautionary measures to mitigate the risk of shoreline erosion within this sensitive zone

EXPERIMENTAL STUDY OF THE MECHANISM EROSION MATERIALS EXPOSED TO LOW PLASMA POWER FLOWS

In this paper, a low activation of ferritic-austentic steel was studied when it was exposed with plasma. The experiment was carried out on a plasma focus device with energy of 1.9 kJ, with a pressure of 2.5 torr of deuterium. AFM analysis shows that cracks up to 2 microns and holes from 81 to 281 nm are found on steel surfaces. The mechanism of the occurrence of erosion of low-activation ferritic-austentic steel is also indicated. It is established that the mechanism of erosion depends on the momentum.

A facile in-situ coating strategy for Ni-rich cathode materials with improved electrochemical performance

A facile in-situ hydrolytic coating strategy has been suggested to architecture LiAlSiO4 (LASO)-coated LiNi0.8Co0.1Mn0.1O2 (LNCM) cathode material for lithium-ion batteries. Homogeneous LASO coating layer, as an one-dimensional lithium ion conductor, on the surface of LNCM is observed clearly and ascertained jointly by several testing methods. The effects of LASO coating layer on physicochemical properties, electrochemical properties and electrochemical kinetics of LNCM cathode material have been rigorously investigated by various tests. The cycling stability, rate capability and Li+ ion diffusion rate are enhanced evidently after LASO coating. Moreover, the polarization, impedance increase and particles cracking after cycles under the high cut-off voltage are greatly improved. These effective and obvious improvements are ascribed to the LASO coating layer, which could effectively inhibit the occurrence of side reactions and HF erosion and provide a fast ion diffusion channel for lithium ions on the surface of LNCM.

Effect of freeze-thaw processes on soil water transport of farmland in a semi-arid area

Seasonal freeze-thaw processes affect soil water migration and distribution, especially in semi-arid agricultural areas. These processes play an important role in mitigating harsh environmental conditions and wind erosion. Soil water content (SWC) and soil temperature (ST) were monitored at different depths (0–2 m) and investigated under freeze-thaw conditions from November 2018 to May 2019 in a semi-arid agro-pastoral region of northern China. The initial SWC was the main factor that affected the freeze-thaw process. During the freeze-thaw process, differences in soil thermal conductivity caused the soil to thaw faster than the freezing process, and the upper soil layer (0–60 cm) was significantly affected by temperature changes. Changes in the potential energy of water and pore pressure gradient caused the migration of soil water to the upper layer, which led to a slight decrease in SWC in each layer before ST dropped to the freezing point. The vertical migration distance of soil water exceeded 70 cm, and the SWC above a depth of 100 cm increased significantly, as water was mainly obtained from the soil layer below a depth of 200 cm. Soil compaction was reduced when affected by freeze-thaw processes and the soil particles were more fragmented, leading to wind erosion and dust events. Our results partially explain the occurrence of wind erosion in spring and provide a scientific basis for predicting soil water status and appropriate farmland management strategies.

Predicting soil erosion and assessing quality indicators in two Brazilian watersheds: subsidy for territorial planning

Soil erosion might be induced by human pressure and result in irreversible environmental impacts. In the municipality of Itapevi (SP, Brazil), where demographic saturation has driven the population to the outskirts of the urban center, changes in land cover and the occupation of environmentally fragile areas of the relief can trigger the erosion process. Hence, we aimed to evaluate erosion susceptibility in two hydrographic sub-basins of Sapiantã. We considered soil quality-related and active erosion occurrence, associated with the Universal Soil Loss Equation. The results indicated that despite strong Natural Potential Erosion, the areas showed soil losses predominantly below 10 t.ha−1.year−1, due to the significant vegetation cover present. The advance of unplanned urbanization in the watershed may contribute to the siltation of water bodies and floods in the central area of the municipality, making it necessary to adopt efficient public policies in preventing soil loss by sheet erosion.

Hazard Assessment and Implementation Strategies for Mitigating of Flood and Erosion in Nigeria

There are notching unresolved issues and environmental hazards traceable to flood and erosion in major rural areas and notable communities in Nigeria. Researchers’ efforts on erosion control and flood mitigation have not yielded notable fruits due to inadequate planning and implementation strategies. Maintenance of roads and other infrastructures are the bed rock of any development round the globe. This paper assessed recent occurrence of flood and erosion. The study examined the causes, urban and regional planning of the affected area, construction practices, damages and maintenance practices. Questionnaires, field study and interview of experts were wont to elicit information from people within the affected location, officials from state and native government agencies charged with rehabilitation of affected areas. The research finding revealed that there are inadequate drainage systems, lack of enforcement of plan, corruptions, failure of systems, poor supervision, construction malpractices, lackadaisical attitude and lack of maintenance culture. Implementation strategies were highlighted to avert flood and erosion ravaging several areas of the country. The paper concluded that stakeholders, researchers, engineers should partner with government agencies within the planning, construction, management and maintenance of rural and concrete drainages for adequate funding and sustainable construction. It is recommended that strategies for alleviating flood and erosion should be implemented supported latest technology for sustainable infrastructural development. Periodic hazard assessment should be planned in various geopolitical zones especially Lagos, Niger delta and rain forest region of Nigeria. Land use control, landscape maintenance, weather stations, proper enforcement of construction works consistent with plan should be strategically put in situ for effective monitoring and alleviation of flood and erosion in Nigeria.

Numerical investigation of electrostatic effect on particle behavior in a 90 degrees bend

Particle behavior in a turbulent circular-sectioned 90° bend under electrostatic field at three air flow rates (1600 L/min, 1100 L/min and 950 L/min, the corresponding bulk Reynolds numbers are 58,000, 40,000, 34,000) is simulated by a Large Eddy Simulation-Lagrangian particle tracking technique (LES-LPT) method coupled with electrostatic field model by Coulomb’s law. This numerical simulation is dedicated to study the electrostatic effect on particle behavior and erosion occurred in the dilute particle-laden bend flow. Forces considered acting on particles includes drag, lift, gravity and electrostatic force. Results obtained for the fluid phase are in good agreement with experimental and numerical data. Predictions show that electrostatic field does affect the particle motion in the pipe bend. At higher air flow rate with higher electrostatics at the inner arc the increasement of impact angle is lower than that at lower flow rate with lower electrostatics. The same conclusion can be found at the outer arc. In addition, electrostatic effect does increase particle-wall impact velocity while such trend decreases with flow rate. Erosion rate increases with increasing air flow rate, which is independent of electrostatics. However, given the same flow rate, the electrostatics reduces the occurrence of erosion at the bend. The erosion rate under electrostatic effect is found to approach that without electrostatics as the flow rate increases. Therefore, the effect of electrostatics on erosion decreases with the air flow rate.

Clinical study on resin composite and glass ionomer materials in II class restorations in permanent teeth.

BackgroundGlass ionomer cements (GIC) used for restoration of missing dental structures have high biocompatibility and remineralization potential. However, low mechanical resistance excludes their use for long-term restorations of extensive lesions, particularly on approximal surfaces in permanent dentition. GIC with increased viscosity have much better physical properties, which involves better bonding and wear resistance, so they can be considered as an alternative to composite resin materials. The aim of this study was to perform a clinical and radiological assessment of restorations in permanent teeth, made with an increased viscosity GIC - Equia Fil (Ivoclar Vivadent) with Equia Coat (Ivoclar Vivadent) and composite material - Tetric EvoCeram (Ivoclar Vivadent) in young patients. Material and MethodsA total of 100 cavities on approximal surfaces were filled with the composite material or GIC in 49 patients aged from 12.08 to 19.58 years. During control examinations, the condition of each restoration was assessed with criteria acc. to Hickel et al. Bitewing radiographs had been taken before fillings were placed and after 12 and 24 months. ResultsAfter two years of observations, two GIC restorations were replaced due to loss of retention and staining. The other 96 restorations were given a satisfactory grade. The clinical efficacy of Equia Fil after 24 months was assessed at 95.83%, the Tetric EvoCeram at 100%. The difference was not statistically significant (P=0.145). When GIC was used, there was a higher risk of marginal adaptation deterioration and the occurrence of staining and erosion. Radiographic efficacy of the Equia Fil material for cavity restoration after 24 months was assessed at 93.75%, for the Tetric EvoCeram material at 100%. Differences were not significant statistically (P=0.073). ConclusionsTetric EvoCeram and Equia Fil used for the restoration of approximal lesions in premolars and permanent molars have similar efficacy in a 2-year period of observation. Key words:Dental restoration, permanent, composite resins, glass ionomer cements, clinical study.