Search results for: median filtering
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 887

Search results for: median filtering

347 Development of a Laboratory Laser-Produced Plasma “Water Window” X-Ray Source for Radiobiology Experiments

Authors: Daniel Adjei, Mesfin Getachew Ayele, Przemyslaw Wachulak, Andrzej Bartnik, Luděk Vyšín, Henryk Fiedorowicz, Inam Ul Ahad, Lukasz Wegrzynski, Anna Wiechecka, Janusz Lekki, Wojciech M. Kwiatek

Abstract:

Laser produced plasma light sources, emitting high intensity pulses of X-rays, delivering high doses are useful to understand the mechanisms of high dose effects on biological samples. In this study, a desk-top laser plasma soft X-ray source, developed for radio biology research, is presented. The source is based on a double-stream gas puff target, irradiated with a commercial Nd:YAG laser (EKSPLA), which generates laser pulses of 4 ns time duration and energy up to 800 mJ at 10 Hz repetition rate. The source has been optimized for maximum emission in the “water window” wavelength range from 2.3 nm to 4.4 nm by using pure gas (argon, nitrogen and krypton) and spectral filtering. Results of the source characterization measurements and dosimetry of the produced soft X-ray radiation are shown and discussed. The high brightness of the laser produced plasma soft X-ray source and the low penetration depth of the produced X-ray radiation in biological specimen allows a high dose rate to be delivered to the specimen of over 28 Gy/shot; and 280 Gy/s at the maximum repetition rate of the laser system. The source has a unique capability for irradiation of cells with high pulse dose both in vacuum and He-environment. Demonstration of the source to induce DNA double- and single strand breaks will be discussed.

Keywords: laser produced plasma, soft X-rays, radio biology experiments, dosimetry

Procedia PDF Downloads 588
346 Assessment of the Neuroprotective Effect of Oral Hypoglycemic Agents in Patients with Acute Ischemic Stroke

Authors: A. Alhusban, M. Alqawasmeh, F. Alfawares

Abstract:

Introduction: Diabetes is a chronic health problem and a major risk factor of stroke. A number of therapeutic modalities exist for diabetes management. It’s still unknown whether the different oral hypoglycemic agents would ameliorate the detrimental effect of diabetes on stroke severity. The objective of this work is to assess the effect of pretreatment with oral hypoglycemic agents, insulin and their combination on stroke severity at presentation. Patients and Methods: Patients admitted to the King Abdullah University Hospital (KAUH)-Jordan with ischemic stroke between January 2015 and December 2016 were evaluated and their comorbid diseases, treatment on admission and their neurologic severity was assessed using the National Institute of Health Stroke Scale (NIHSS) were documented. Stroke severity was compared for non-diabetic patients and diabetic patients treated with different antidiabetic agents. Results: Data from 324 patients with acute stroke was documented. The median age of participants was 69 years. Diabetes was documented in about 50% of the patients. Multinomial regression analysis identified diabetes treatment status as an independent predictor of neurological severity of stroke (p=0.032). Patients treated with oral hypoglycemic agents had a significantly lower NIHSS as compared to nondiabetic patients and insulin treated patients (p < 0.02). The positive effect of oral hypoglycemic agents was blunted by insulin co-treatment. Insulin did not alter the severity of stroke as compared to non-diabetics. Conclusion: Oral hypoglycemic agents may reduce the severity of neurologic deficit of ischemic stroke and may have neuroprotective effect.

Keywords: diabetes, stroke, neuroprotection, oral hypoglycemic agents

Procedia PDF Downloads 164
345 Noise Mitigation Techniques to Minimize Electromagnetic Interference/Electrostatic Discharge Effects for the Lunar Mission Spacecraft

Authors: Vabya Kumar Pandit, Mudit Mittal, N. Prahlad Rao, Ramnath Babu

Abstract:

TeamIndus is the only Indian team competing for the Google Lunar XPRIZE(GLXP). The GLXP is a global competition to challenge the private entities to soft land a rover on the moon, travel minimum 500 meters and transmit high definition images and videos to Earth. Towards this goal, the TeamIndus strategy is to design and developed lunar lander that will deliver a rover onto the surface of the moon which will accomplish GLXP mission objectives. This paper showcases the various system level noise control techniques adopted by Electrical Distribution System (EDS), to achieve the required Electromagnetic Compatibility (EMC) of the spacecraft. The design guidelines followed to control Electromagnetic Interference by proper electronic package design, grounding, shielding, filtering, and cable routing within the stipulated mass budget, are explained. The paper also deals with the challenges of achieving Electromagnetic Cleanliness in presence of various Commercial Off-The-Shelf (COTS) and In-House developed components. The methods of minimizing Electrostatic Discharge (ESD) by identifying the potential noise sources, susceptible areas for charge accumulation and the methodology to prevent arcing inside spacecraft are explained. The paper then provides the EMC requirements matrix derived from the mission requirements to meet the overall Electromagnetic compatibility of the Spacecraft.

Keywords: electromagnetic compatibility, electrostatic discharge, electrical distribution systems, grounding schemes, light weight harnessing

Procedia PDF Downloads 293
344 Molluscicidal Activity of Some Aqueous and Organic Extract from Some Asteraceae

Authors: Lineda Rouissat-Dahane, Abdelkrim Cheriti, Abbderazak Marouf, Reddy Kandappa H., Govender Patrick

Abstract:

Natural phytochemicals extracted from folk herbal have drawn much attention in complementary and alternative medicine, and the plant kingdom is considered for developing new molluscicide. The aqueous and acetone extract of the aerial parts of some Asteraceae (Anvillea radiata, Bubonium graveolens, Launaea arborescens, Launaea nudicaulis and Warionia saharae) were investigated for its molluscicidal activity against Lymnaea acuminata showed significant molluscicidal activity with a median lethal concentration (LC50) of aqueous extract (8,178mg/ml) and organic extract 0.002μg/mL, which was indicated higher potency than the positive control, (LC50=100mg /mL for aqueous extract ; LC50=11.6 μg/mL for organic extract). Among the extract and their fractions, those of aerial parts of Launaea nudicaulis and Warionia saharae were found to exhibit significant molluscicidal activities. Among different solvent fractions of the acetone extract of Warionia saharae, the dichloromethane (DCM) soluble fraction showed the most potent molluscicidal activity against Lymnaea acuminata. Plants in species Anvillea radiata, Bubonium graveolens, Launaea arborescens, Launaea nudicaulis, and Warionia saharae produce a great variety of Flavonoids, Glucoside flavonoids, and Saponins that confer natural resistance against several pests. Most extracts were found to exhibit significant molluscicidal activity.

Keywords: acetone extract, aqueous extract, Asteraceae, molluscicidal activity, Lymnaea acuminata

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343 Comparison of the Glidescope Visualization and Neck Flexion with Lateral Neck Pressure Nasogastric Tube Insertion Techniques in Anaesthetized Patients: A Prospective Randomized Clinical Study

Authors: Pitchaporn Purngpiputtrakul, Suttasinee Petsakul, Sunisa Chatmongkolchart

Abstract:

Nasogastric tube (NGT) insertion in anaesthetized and intubated patients can be challenging even for experienced anesthesiologists. Various techniques have been proposed to facilitate NGT insertion in these patients. This study aimed to compare the success rate and time required for NGT insertion between the GlideScope visualization and neck flexion with lateral neck pressure techniques. This randomized clinical trial was performed at a teaching hospital on 86 adult patients undergoing abdominal surgery under relaxant general anaesthesia who required intraoperative NGT insertion. The patients were randomized into two groups, the GlideScope group (group G) and the neck flexion with lateral neck pressure group (group F). The success rate of first and second attempts, duration of insertion, and complications were recorded. The total success rate was 79.1% in Group G compared with 76.7% in Group F (P=1) The median time required for NGT insertion was significantly longer in Group G, for both first and second attempts (97 vs 42 seconds P<0.001) and (70 vs 48.5 seconds P=0.015), respectively. Complications were reported in 23 patients (53.5%) in group G and 13 patients (30.2%) in group F. Bleeding and kinking were the most common complications in both techniques. Using GlideScope visualization to facilitate NGT insertion was comparable to neck flexion with lateral neck pressure technique in degree of success rate of insertion, while neck flexion with lateral neck pressure technique had fewer complications and was less time-consuming.

Keywords: anaesthesia, nasogastric tube, GlideScope, intubation

Procedia PDF Downloads 165
342 Identification of Spam Keywords Using Hierarchical Category in C2C E-Commerce

Authors: Shao Bo Cheng, Yong-Jin Han, Se Young Park, Seong-Bae Park

Abstract:

Consumer-to-Consumer (C2C) E-commerce has been growing at a very high speed in recent years. Since identical or nearly-same kinds of products compete one another by relying on keyword search in C2C E-commerce, some sellers describe their products with spam keywords that are popular but are not related to their products. Though such products get more chances to be retrieved and selected by consumers than those without spam keywords, the spam keywords mislead the consumers and waste their time. This problem has been reported in many commercial services like e-bay and taobao, but there have been little research to solve this problem. As a solution to this problem, this paper proposes a method to classify whether keywords of a product are spam or not. The proposed method assumes that a keyword for a given product is more reliable if the keyword is observed commonly in specifications of products which are the same or the same kind as the given product. This is because that a hierarchical category of a product in general determined precisely by a seller of the product and so is the specification of the product. Since higher layers of the hierarchical category represent more general kinds of products, a reliable degree is differently determined according to the layers. Hence, reliable degrees from different layers of a hierarchical category become features for keywords and they are used together with features only from specifications for classification of the keywords. Support Vector Machines are adopted as a basic classifier using the features, since it is powerful, and widely used in many classification tasks. In the experiments, the proposed method is evaluated with a golden standard dataset from Yi-han-wang, a Chinese C2C e-commerce, and is compared with a baseline method that does not consider the hierarchical category. The experimental results show that the proposed method outperforms the baseline in F1-measure, which proves that spam keywords are effectively identified by a hierarchical category in C2C e-commerce.

Keywords: spam keyword, e-commerce, keyword features, spam filtering

Procedia PDF Downloads 294
341 Sociodemographic Predictors of Flourishing among Older Adults in Rural and Urban Mongolia

Authors: Saranchuluun Otgon, Sugarmaa Myagmarjav, Khorolsuren Lkhagvasuren, Fabio Casati

Abstract:

Background: Flourishing is a eudaimonic dimension of psychological well-being that has been associated with positive social and health-related outcomes. Determining the factors associated with health and well-being is important to the development of evidence-based intervention programs, policies, and action plans targeting the older adult population, especially in low- and middle-income countries, such as Mongolia, where evidence-based research on aging, health, and well-being is still scarce. This study makes important contributions to the study of well-being in later age and also to policy activities for the older population in Mongolia. Methods: We employed multiple regression models to predict the factors of flourishing using data from 304 older adults living in urban and rural Mongolia. Data is collected by the standardized and validated questionnaire adopted by Ed Diener. Results: The median score of the flourishing of urban and rural older adults in Mongolia was significantly different, 53 and 50, respectively. The sex (β = 2.52,p = 0.034), level of education(β = 0.94, p = 0.026), receive help for the activity of daily living (β = 2.16, p = 0.022) determine the flourishing of older adults living in a rural area, while self-reported health (β = 0.94, p = 0.026), the number of social activities, friends network determine to flourish of older adults living urban area. Conclusion: Older adults who live in urban areas have more psychological resources and strengths than those in rural areas. Determinants of flourishing are different in different settings. For instance, individual and family factors determine flourishing in rural areas, and social ties determine flourishing in urban areas.

Keywords: flourishing, predictors, older adults, Mongolia, psychological well-being

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340 Implementation of a Monostatic Microwave Imaging System using a UWB Vivaldi Antenna

Authors: Babatunde Olatujoye, Binbin Yang

Abstract:

Microwave imaging is a portable, noninvasive, and non-ionizing imaging technique that employs low-power microwave signals to reveal objects in the microwave frequency range. This technique has immense potential for adoption in commercial and scientific applications such as security scanning, material characterization, and nondestructive testing. This work presents a monostatic microwave imaging setup using an Ultra-Wideband (UWB), low-cost, miniaturized Vivaldi antenna with a bandwidth of 1 – 6 GHz. The backscattered signals (S-parameters) of the Vivaldi antenna used for scanning targets were measured in the lab using a VNA. An automated two-dimensional (2-D) scanner was employed for the 2-D movement of the transceiver to collect the measured scattering data from different positions. The targets consist of four metallic objects, each with a distinct shape. Similar setup was also simulated in Ansys HFSS. A high-resolution Back Propagation Algorithm (BPA) was applied to both the simulated and experimental backscattered signals. The BPA utilizes the phase and amplitude information recorded over a two-dimensional aperture of 50 cm × 50 cm with a discreet step size of 2 cm to reconstruct a focused image of the targets. The adoption of BPA was demonstrated by coherently resolving and reconstructing reflection signals from conventional time-of-flight profiles. For both the simulation and experimental data, BPA accurately reconstructed a high resolution 2D image of the targets in terms of shape and location. An improvement of the BPA, in terms of target resolution, was achieved by applying the filtering method in frequency domain.

Keywords: back propagation, microwave imaging, monostatic, vivialdi antenna, ultra wideband

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339 Peripheral Nerves Cross-Sectional Area for the Diagnosis of Diabetic Polyneuropathy: A Meta-Analysis of Ultrasonographic Measurements

Authors: Saeed Pourhassan, Nastaran Maghbouli

Abstract:

1) Background It has been hypothesized that, in individuals with diabetes mellitus, the peripheral nerve is swollen due to sorbitol over-accumulation. Additionally growing evidence supported electro diagnostic study of diabetes induced neuropathy as a method having some challenges. 2) Objective To examine the performance of sonographic cross-sectional area (CSA) measurements in the diagnosis of diabetic polyneuropathy (DPN). 3) Data Sources Electronic databases, comprising PubMed and EMBASE and Google scholar, were searched for the appropriate studies before Jan 1, 2020. 4) Study Selection Eleven trials comparing different peripheral nerve CSA measurements between participants with and without DPN were included. 5) Data Extraction Study design, participants' demographic characteristics, diagnostic reference of DPN, and evaluated peripheral nerves and methods of CSA measurement. 6) Data Synthesis Among different peripheral nerves, Tibial nerve diagnostic odds ratios pooled from five studies (713 participants) were 4.46 (95% CI, 0.35–8.57) and the largest one with P<0.0001, I²:64%. Median nerve CSA at wrist and mid-arm took second and third place with ORs= 2.82 (1.50-4.15), 2.02(0.26-3.77) respectively. The sensitivities and specificities pooled from two studies for Sural nerve were 0.78 (95% CI, 0.68–0.89), and 0.68 (95% CI, 0.53–0.74). Included studies for other nerves were limited to one study. The largest sensitivity was for Sural nerve and the largest specificity was for Tibial nerve. 7) Conclusions The peripheral nerves CSA measured by ultrasound imaging is useful for the diagnosis of DPN and is most significantly different between patients and participants without DPN at the Tibial nerve. Because the Tibial nerve CSA in healthy participants, at various locations, rarely exceeds 24 mm2, this value can be considered as a cutoff point for diagnosing DPN.

Keywords: diabetes, diagnosis, polyneuropathy, ultrasound

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338 Creating Risk Maps on the Spatiotemporal Occurrence of Agricultural Insecticides in Sub-Saharan Africa

Authors: Chantal Hendriks, Harry Gibson, Anna Trett, Penny Hancock, Catherine Moyes

Abstract:

The use of modern inputs for crop protection, such as insecticides, is strongly underestimated in Sub-Saharan Africa. Several studies measured toxic concentrations of insecticides in fruits, vegetables and fish that were cultivated in Sub-Saharan Africa. The use of agricultural insecticides has impact on human and environmental health, but it also has the potential to impact on insecticide resistance in malaria transmitting mosquitos. To analyse associations between historic use of agricultural insecticides and the distribution of insecticide resistance through space and time, the use and environmental fate of agricultural insecticides needs to be mapped through the same time period. However, data on the use and environmental fate of agricultural insecticides in Africa are limited and therefore risk maps on the spatiotemporal occurrence of agricultural insecticides are created using environmental data. Environmental data on crop density and crop type were used to select the areas that most likely receive insecticides. These areas were verified by a literature review and expert knowledge. Pesticide fate models were compared to select most dominant processes that are involved in the environmental fate of insecticides and that can be mapped at a continental scale. The selected processes include: surface runoff, erosion, infiltration, volatilization and the storing and filtering capacity of soils. The processes indicate the risk for insecticide accumulation in soil, water, sediment and air. A compilation of all available data for traces of insecticides in the environment was used to validate the maps. The risk maps can result in space and time specific measures that reduce the risk of insecticide exposure to non-target organisms.

Keywords: crop protection, pesticide fate, tropics, insecticide resistance

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337 The Neutrophil-to-Lymphocyte Ratio after Surgery for Hip Fracture in a New, Simple, and Objective Score to Predict Postoperative Mortality

Authors: Philippe Dillien, Patrice Forget, Harald Engel, Olivier Cornu, Marc De Kock, Jean Cyr Yombi

Abstract:

Introduction: Hip fracture precedes commonly death in elderly people. Identification of high-risk patients may contribute to target patients in whom optimal management, resource allocation and trials efficiency is needed. The aim of this study is to construct a predictive score of mortality after hip fracture on the basis of the objective prognostic factors available: Neutrophil-to-lymphocyte ratio (NLR), age, and sex. C-Reactive Protein (CRP), is also considered as an alternative to the NLR. Patients and methods: After the IRB approval, we analyzed our prospective database including 286 consecutive patients with hip fracture. A score was constructed combining age (1 point per decade above 74 years), sex (1 point for males), and NLR at postoperative day+5 (1 point if >5). A receiver-operating curve (ROC) curve analysis was performed. Results: From the 286 patients included, 235 were analyzed (72 males and 163 females, 30.6%/69.4%), with a median age of 84 (range: 65 to 102) years, mean NLR values of 6.47+/-6.07. At one year, 82/280 patients died (29.3%). Graphical analysis and log-rank test confirm a highly statistically significant difference (P<0.001). Performance analysis shows an AUC of 0.72 [95%CI 0.65-0.79]. CRP shows no advantage on NLR. Conclusion: We have developed a score based on age, sex and the NLR to predict the risk of mortality at one year in elderly patients after surgery for a hip fracture. After external validation, it may be included in clinical practice as in clinical research to stratify the risk of postoperative mortality.

Keywords: neutrophil-to-lymphocyte ratio, hip fracture, postoperative mortality, medical and health sciences

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336 Acute Poisoning Based on Age and Gender Caused by Pharmaceuticals and Therapies That Influence the Nervous System

Authors: Ragy Raafat Gaber Attaalla

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Background: We looked at acute poisonings brought on by illegal drugs and pharmaceuticals that influence the nervous system at Assiut University Hospitals. Methods: Between January 2010 and December 2015, we conducted a retrospective examination of patient records from the largest tertiary toxicology referral center in Assiut. We examined the frequency, pattern, and distribution of ages and genders of acute nervous system agent poisoning. Results: 29,083 individuals total—16,657 (57.27%) males and 12,426 (42.73%) females—were included in the current study. Men's and women's median ages were 29 and 26, respectively (p < 0.0001). 10,326 (83.10%) women and 12,071 (72.47%) men under 40 were present (p < 0.001). 44.10% of cases had a history of poisoning, and the majority of cases (69.38% in men and 79.00% in women, p<0.001) were purposeful. Between various age groups and nervous system agents, there were notable variations in the ratios of men and women. The most often used agent for women was alprazolam, whereas methadone was more popular for men. Overall, there was a rising tendency in acute poisoning associated with alcohol and opioids used to treat addiction disorders, but a declining trend with benzodiazepines and antidepressants. Conclusion: Addiction to methadone was widespread, particularly in young males, and the majority of these cases were self-inflicted. Alprazolam and clonazepam poisoning most commonly affect women and males in the 20–29 age range, respectively. Opium was utilized by men over 30 and women over 60. Over half of the deaths were related to illicit narcotics, with opium being the most common. This research could raise awareness and lead to the development of gender- and age-specific local programs for education and prevention.

Keywords: acute poisonings, illegal drugs, pharmaceuticals, nerve system

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335 The Prevalence of Blood-Borne Viral Infections among Autopsy Cases in Jordan

Authors: Emad Al-Abdallat, Faris G. Bakri, Azmi Mahafza, Rayyan Al Ali, Nidaa Ababneh, Ahmed Idhair

Abstract:

Background: Morgues are high-risk areas for the spread of infection from the cadavers to the staff during the postmortem examination. Infection can spread from corpses to workers by the airborne route, by direct contact, or from needle and sharp object injuries. Objective: Knowledge about the prevalence of these infections among autopsies is prudent to appreciate any risk of transmission and to further enforce safety measures. Method: A total of 242 autopsies were tested. Age ranged from 3 days to 94 years (median 75.5 years, mean 45.3 (21.9 ± SD)). There were 172 (71%) males. Results: The cause of death was considered natural in 137 (56.6%) cases, accidental in 89 (36.8%), homicidal in 9 (3.7%), suicidal in 4 (1.7%), and unknown in 3 (1.2%). Hepatitis B surface antigen was positive in 5 (2.1%) cases. Hepatitis C virus antibody was detected in 5 (2.1%) cases and the hepatitis C virus polymerase chain reaction was positive in 2 of them (0.8%). HIV antibody was not detected in any of the cases. Conclusions: Autopsies can be associated with exposure to blood borne viruses. Autopsies performed during the study period were tested for hepatitis B surface antigen, hepatitis C virus antibody, and human immunodeficiency virus antibody. Positive tests were subsequently confirmed by polymerase chain reaction. There is low prevalence of infections with these viruses in our autopsy cases. However, the risk of transmission remains a threat. Healthcare workers in the forensic departments should adhere to standard precautions.

Keywords: autopsy, hepatitis B virus, hepatitis C virus, human immunodeficiency virus, Jordan

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334 Clinical Outcome after in Vitro Fertilization in Women Aged 40 Years and Above: Reasonable Cut-Off Age for Successful Pregnancy

Authors: Eun Jeong Yu, Inn Soo Kang, Tae Ki Yoon, Mi Kyoung Koong

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Advanced female age is associated with higher cycle cancelation rates, lower clinical pregnancy rate, increased miscarriage and aneuploidy rates in IVF (In Vitro Fertilization) cycles. This retrospective cohort study was conducted at a Cha Fertility Center, Seoul Station. All fresh non-donor IVF cycles performed in women aged 40 years and above from January 2016 to December 2016 were reviewed. Donor/recipient treatment, PGD/PGS (Preimplantation Genetic Diagnosis/ Preimplantation Genetic Screening) were excluded from analysis. Of the 1,166 cycles from 753 women who completed ovulation induction, 1,047 were appropriate for the evaluation according to inclusion and exclusion criterion. IVF cycles were categorized according to age and grouped into the following 1-year age groups: 40, 41, 42, 43, 44, 45 and > 46. The mean age of patients was 42.4 ± 1.8 years. The median AMH (Anti-Mullerian Hormone) level was 1.2 ± 1.5 ng/mL. The mean number of retrieved oocytes was 4.9 ± 4.3. The clinical pregnancy rate and live birth rate in women > 40 years significantly decreased with each year of advancing age (p < 0.001). The clinical pregnancy rate decreased from 21% at the age of 40 years to 0% at ages above 45 years. Live birth rate decreased from 12.3% to 0%, respectively. There were no clinical pregnancy outcomes among 95 patients aged above 45 years of age. The overall miscarriage rate was 40.7% (range, 36.7%-70%). The transfer of at least one good quality embryo was associated with about 4-9% increased chance of a clinical pregnancy rate. Therefore, IVF in old age women less than 46 had a reasonable chance for successful pregnancy outcomes especially when good quality embryo is transferred.

Keywords: advanced maternal age, in vitro fertilization, pregnancy rate, live birth rate

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333 Empowering Transformers for Evidence-Based Medicine

Authors: Jinan Fiaidhi, Hashmath Shaik

Abstract:

Breaking the barrier for practicing evidence-based medicine relies on effective methods for rapidly identifying relevant evidence from the body of biomedical literature. An important challenge confronted by medical practitioners is the long time needed to browse, filter, summarize and compile information from different medical resources. Deep learning can help in solving this based on automatic question answering (Q&A) and transformers. However, Q&A and transformer technologies are not trained to answer clinical queries that can be used for evidence-based practice, nor can they respond to structured clinical questioning protocols like PICO (Patient/Problem, Intervention, Comparison and Outcome). This article describes the use of deep learning techniques for Q&A that are based on transformer models like BERT and GPT to answer PICO clinical questions that can be used for evidence-based practice extracted from sound medical research resources like PubMed. We are reporting acceptable clinical answers that are supported by findings from PubMed. Our transformer methods are reaching an acceptable state-of-the-art performance based on two staged bootstrapping processes involving filtering relevant articles followed by identifying articles that support the requested outcome expressed by the PICO question. Moreover, we are also reporting experimentations to empower our bootstrapping techniques with patch attention to the most important keywords in the clinical case and the PICO questions. Our bootstrapped patched with attention is showing relevancy of the evidence collected based on entropy metrics.

Keywords: automatic question answering, PICO questions, evidence-based medicine, generative models, LLM transformers

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332 Utility of Optical Coherence Tomography (OCT) and Visual Field Assessment in Neurosurgical Patients

Authors: Ana Ferreira, Ines Costa, Patricia Polónia, Josué Pereira, Olinda Faria, Pedro Alberto Silva

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Introduction: Optical coherence tomography (OCT) and visual field tools are pivotal in evaluating neurological deficits and predicting potential visual improvement following surgical decompression in neurosurgical patients. Despite their clinical significance, a comprehensive understanding of their utility in this context is lacking in the literature. This study aims to elucidate the applications of OCT and visual field assessment, delineating distinct patterns of visual deficit presentations within the studied cohort. Methods: This retrospective analysis considered all adult patients who underwent a single surgery for pituitary adenoma or anterior skull base meningioma with optic nerve involvement, coupled with neuro-ophthalmology evaluation, between July 2020 and January 2023. A minimum follow-up period of 6 months was deemed essential. Results: A total of 24 patients, with a median age of 61, were included in the analysis. Three primary patterns emerged: 1) Low visual field involvement with compromised OCT, 2) High visual field involvement with relatively unaffected OCT, and 3) Significant compromise observed in both OCT and visual fields. Conclusion: This study delineates various findings in OCT and visual field assessments with illustrative examples. Based on the current findings, a prospective cohort will be systematically collected to further investigate and validate these patterns and their prognostic significance, enhancing our understanding of the utility of OCT and visual fields in neurosurgical patients.

Keywords: OCT, neurosurgery, visual field, optic nerve

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331 Clouds Influence on Atmospheric Ozone from GOME-2 Satellite Measurements

Authors: S. M. Samkeyat Shohan

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This study is mainly focused on the determination and analysis of the photolysis rate of atmospheric, specifically tropospheric, ozone as function of cloud properties through-out the year 2007. The observational basis for ozone concentrations and cloud properties are the measurement data set of the Global Ozone Monitoring Experiment-2 (GOME-2) sensor on board the polar orbiting Metop-A satellite. Two different spectral ranges are used; ozone total column are calculated from the wavelength window 325 – 335 nm, while cloud properties, such as cloud top height (CTH) and cloud optical thick-ness (COT) are derived from the absorption band of molecular oxygen centered at 761 nm. Cloud fraction (CF) is derived from measurements in the ultraviolet, visible and near-infrared range of GOME-2. First, ozone concentrations above clouds are derived from ozone total columns, subtracting the contribution of stratospheric ozone and filtering those satellite measurements which have thin and low clouds. Then, the values of ozone photolysis derived from observations are compared with theoretical modeled results, in the latitudinal belt 5˚N-5˚S and 20˚N - 20˚S, as function of CF and COT. In general, good agreement is found between the data and the model, proving both the quality of the space-borne ozone and cloud properties as well as the modeling theory of ozone photolysis rate. The found discrepancies can, however, amount to approximately 15%. Latitudinal seasonal changes of photolysis rate of ozone are found to be negatively correlated to changes in upper-tropospheric ozone concentrations only in the autumn and summer months within the northern and southern tropical belts, respectively. This fact points to the entangled roles of temperature and nitrogen oxides in the ozone production, which are superimposed on its sole photolysis induced by thick and high clouds in the tropics.

Keywords: cloud properties, photolysis rate, stratospheric ozone, tropospheric ozone

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330 Patterns, Triggers, and Predictors of Relapses among Children with Steroid Sensitive Idiopathic Nephrotic Syndrome at the University of Abuja Teaching Hospital, Gwagwalada, Abuja, Nigeria

Authors: Emmanuel Ademola Anigilaje, Ibraheem Ishola

Abstract:

Background: Childhood steroid-sensitive idiopathic nephrotic syndrome (SSINS) is plagued with relapses that contribute to its morbidity and the cost of treatment. Materials and Methods: This is a retrospective review of relapses among children with SSINS at the University of Abuja Teaching Hospital from January 2016 to July 2020. Triggers related to relapse incidents were noted. Chi-square test was deployed for predictors (factors at the first clinical presentations that associate with subsequent relapses) of relapses. Predictors with p-values of less than 0.05 were considered significant and 95% confidence intervals (CI) and odd ratio (OR) were described. Results: Sixty SSINS comprising 52 males (86.7%), aged 23 months to 18 years, with a mean age of 7.04±4.16 years were studied. Thirty-eight (63.3%) subjects had 126 relapses including infrequent relapses in 30 (78.9%) and frequent relapses in 8 (21.1%). The commonest triggers were acute upper respiratory tract infections (68, 53.9%) and urinary tract infections (UTIs) in 25 (19.8%) relapses. In 4 (3.2%) relapses, no trigger was identified. The time-to-first relapse ranged 14 days to 365 days with a median time of 60 days. The significant predictors were hypertension (OR=3.4, 95% CI; 1.04-11.09, p=0.038), UTIs (OR=9.9, 95% CI; 1.16-80.71, p= 0.014), malaria fever (OR=8.0, 95% CI; 2.45-26.38, p˂0.001), micro-haematuria (OR=4.9, 95% CI; 11.58-15.16, p=0.004), elevated serum creatinine (OR=12.3, 95%CI; 1.48-101.20, p=0.005) and hypercholesterolaemia (OR=4.1, 95%CI; 1.35-12.63, p=0.011). Conclusion: While the pathogenesis of relapses remains unknown, it is prudent to consider relapse-specific preventive strategies against triggers and predictors of relapses in our setting.

Keywords: Patterns, triggers, predictors, steroid-sensitive idiopathic nephrotic syndrome, relapses, Nigeria

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329 The Effects of Collaborative Reflection and Class Observation on Improving the Quality of Teacher-Training Courses

Authors: Somayeh Sharifi

Abstract:

The purpose of this study is to investigate the effects of collaborative reflection and class observation on improving the quality of teacher training courses and the students reading comprehension skills. 13 inexperienced English teachers teaching elementary courses that were at the same level of proficiency were chosen. Thirteen participants were allocated in two groups, with 7 teachers in the experimental group and the other 6 teachers in the control group. Since two groups were not selected randomly, this study is a form of quasi-experimental research. In addition to a 3-day teacher training course for both groups, teachers in experimental group recorded and observed 20 sessions of their own classes and 30 sessions of experienced teachers’ class and participated in 12 meetings -3 month once a week- in which teachers shared any event that they found interesting during observations and their own teaching and compare it with strategies that they learned in teacher training courses. In contrast, the control group did not engage in any process of observation and collaboration. In order to test students' performance in English before and after the treatment, a Key English Test (KET) was employed to check students' reading skill. The result of the test shows that there is not a significant difference in mean of scores in KET pretest in and, since they are close to each other. However by considering mean and median of posttest in both classes we perceive that although both control and experimental group students' proficiency in English enhanced, there was a significant difference in experimental group students' final scores before and after treatment.

Keywords: collaborative reflection, reading comprehension, teacher training courses, key English test (KET)

Procedia PDF Downloads 356
328 Diagnostic Efficacy and Usefulness of Digital Breast Tomosynthesis (DBT) in Evaluation of Breast Microcalcifications as a Pre-Procedural Study for Stereotactic Biopsy

Authors: Okhee Woo, Hye Seon Shin

Abstract:

Purpose: To investigate the diagnostic power of digital breast tomosynthesis (DBT) in evaluation of breast microcalcifications and usefulness as a pre-procedural study for stereotactic biopsy in comparison with full-field digital mammogram (FFDM) and FFDM plus magnification image (FFDM+MAG). Methods and Materials: An IRB approved retrospective observer performance study on DBT, FFDM, and FFDM+MAG was done. Image quality was rated in 5-point scoring system for lesion clarity (1, very indistinct; 2, indistinct; 3, fair; 4, clear; 5, very clear) and compared by Wilcoxon test. Diagnostic power was compared by diagnostic values and AUC with 95% confidence interval. Additionally, procedural report of biopsy was analysed for patient positioning and adequacy of instruments. Results: DBT showed higher lesion clarity (median 5, interquartile range 4-5) than FFDM (3, 2-4, p-value < 0.0001), and no statistically significant difference to FFDM+MAG (4, 4-5, p-value=0.3345). Diagnostic sensitivity and specificity of DBT were 86.4% and 92.5%; FFDM 70.4% and 66.7%; FFDM+MAG 93.8% and 89.6%. The AUCs of DBT (0.88) and FFDM+MAG (0.89) were larger than FFDM (0.59, p-values < 0.0001) but there was no statistically significant difference between DBT and FFDM+MAG (p-value=0.878). In 2 cases with DBT, petit needle could be appropriately prepared; and other 3 without DBT, patient repositioning was needed. Conclusion: DBT showed better image quality and diagnostic values than FFDM and equivalent to FFDM+MAG in the evaluation of breast microcalcifications. Evaluation with DBT as a pre-procedural study for breast stereotactic biopsy can lead to more accurate localization and successful biopsy and also waive the need for additional magnification images.

Keywords: DBT, breast cancer, stereotactic biopsy, mammography

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327 An Amended Method for Assessment of Hypertrophic Scars Viscoelastic Parameters

Authors: Iveta Bryjova

Abstract:

Recording of viscoelastic strain-vs-time curves with the aid of the suction method and a follow-up analysis, resulting into evaluation of standard viscoelastic parameters, is a significant technique for non-invasive contact diagnostics of mechanical properties of skin and assessment of its conditions, particularly in acute burns, hypertrophic scarring (the most common complication of burn trauma) and reconstructive surgery. For elimination of the skin thickness contribution, usable viscoelastic parameters deduced from the strain-vs-time curves are restricted to the relative ones (i.e. those expressed as a ratio of two dimensional parameters), like grosselasticity, net-elasticity, biological elasticity or Qu’s area parameters, in literature and practice conventionally referred to as R2, R5, R6, R7, Q1, Q2, and Q3. With the exception of parameters R2 and Q1, the remaining ones substantially depend on the position of inflection point separating the elastic linear and viscoelastic segments of the strain-vs-time curve. The standard algorithm implemented in commercially available devices relies heavily on the experimental fact that the inflection time comes about 0.1 sec after the suction switch-on/off, which depreciates credibility of parameters thus obtained. Although the Qu’s US 7,556,605 patent suggests a method of improving the precision of the inflection determination, there is still room for nonnegligible improving. In this contribution, a novel method of inflection point determination utilizing the advantageous properties of the Savitzky–Golay filtering is presented. The method allows computation of derivatives of smoothed strain-vs-time curve, more exact location of inflection and consequently more reliable values of aforementioned viscoelastic parameters. An improved applicability of the five inflection-dependent relative viscoelastic parameters is demonstrated by recasting a former study under the new method, and by comparing its results with those provided by the methods that have been used so far.

Keywords: Savitzky–Golay filter, scarring, skin, viscoelasticity

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326 Prognosis of Interstitial Lung Disease (ILD) Based on Baseline Pulmonary Function Test (PFT) Results in Omani Adult Patients Diagnosed with ILD In Sultan Qaboos University Hospital

Authors: Manal Al Bahri, Saif Al Mubahisi, Shamsa Al Shahaimi, Asma Al Qasabi, Jamal Al Aghbari

Abstract:

Introduction: ILD is a common disease worldwide and in Oman. No previous Omani study was published regarding ILD prognosis based on baseline PFT results and other factors. This study aims to determine the severity of ILD by the baseline PFT, correlate between baseline PFT and outcome, and study other factors that influence disease mortality. Method: It is a retrospective cohort study; data was collected from January 2011 to December 2021 from electronic patient records (EPR). Means, Standard Deviations, frequencies, and Chi-square tests were used to examine the different variables in the study. Results: The total population of the study was 146 patients; 87 (59.6%) were females, and 59 (40.4%) were males. The median age was 59 years. Age at diagnosis, CVA, rheumatological disease, and baseline FVC were found to be statistically significant predictors of mortality .59.6% of the patients are diagnosed with IPF. Most of our study patients had mild disease based on baseline FVC. Death was higher with the more severe disease based on FVC. In mild disease (FVC >70%), 26.9% of the patients died. In moderate disease (FVC 50-69%),55.7% of the patients died, and in the severe group (FVC <50 %), 55.1% died. This was statistically significant with a P value of 0. 001. There is no statistically significant difference in the overall survival distribution between the different groups of DLCO. Conclusion: In our study, we found that ILD is more common among females, but death is more common among males. Based on baseline PFT, we can predict mortality by FVC level, as moderate to severe limitation is associated with a lower survival rate. DLCO was not a statistically significant parameter associated with mortality.

Keywords: PFT, ILD, FVC, DLCO, mortality

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325 Post-Traumatic Stress Disorder: Management at the Montfort Hospital

Authors: Kay-Anne Haykal, Issack Biyong

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The post-traumatic stress disorder (PTSD) rises from exposure to a traumatic event and appears by a persistent experience of this event. Several psychiatric co-morbidities are associated with PTSD and include mood disorders, anxiety disorders, and substance abuse. The main objective was to compare the criteria for PTSD according to the literature to those used to diagnose a patient in a francophone hospital and to check the correspondence of these two criteria. 700 medical charts of admitted patients on the medicine or psychiatric unit at the Montfort Hospital were identified with the following diagnoses: major depressive disorder, bipolar disorder, anxiety disorder, substance abuse, and PTSD for the period of time between April 2005 and March 2006. Multiple demographic criteria were assembled. Also, for every chart analyzed, the PTSD criteria, according to the Manual of Mental Disorders (DSM) IV were found, identified, and grouped according to pre-established codes. An analysis using the receiver operating characteristic (ROC) method was elaborated for the study of data. A sample of 57 women and 50 men was studied. Age was varying between 18 and 88 years with a median age of 48. According to the PTSD criteria in the DSM IV, 12 patients should have the diagnosis of PTSD in opposition to only two identified in the medical charts. The ROC method establishes that with the combination of data from PTSD and depression, the sensitivity varies between 0,127 and 0,282, and the specificity varies between 0,889 and 0,917. Otherwise, if we examine the PTSD data alone, the sensibility jumps to 0.50, and the specificity varies between 0,781 and 0,895. This study confirms the presence of an underdiagnosed and treated PTSD that causes severe perturbations for the affected individual.

Keywords: post-traumatic stress disorder, co-morbidities, diagnosis, mental health disorders

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324 Accelerating Quantum Chemistry Calculations: Machine Learning for Efficient Evaluation of Electron-Repulsion Integrals

Authors: Nishant Rodrigues, Nicole Spanedda, Chilukuri K. Mohan, Arindam Chakraborty

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A crucial objective in quantum chemistry is the computation of the energy levels of chemical systems. This task requires electron-repulsion integrals as inputs, and the steep computational cost of evaluating these integrals poses a major numerical challenge in efficient implementation of quantum chemical software. This work presents a moment-based machine-learning approach for the efficient evaluation of electron-repulsion integrals. These integrals were approximated using linear combinations of a small number of moments. Machine learning algorithms were applied to estimate the coefficients in the linear combination. A random forest approach was used to identify promising features using a recursive feature elimination approach, which performed best for learning the sign of each coefficient but not the magnitude. A neural network with two hidden layers were then used to learn the coefficient magnitudes along with an iterative feature masking approach to perform input vector compression, identifying a small subset of orbitals whose coefficients are sufficient for the quantum state energy computation. Finally, a small ensemble of neural networks (with a median rule for decision fusion) was shown to improve results when compared to a single network.

Keywords: quantum energy calculations, atomic orbitals, electron-repulsion integrals, ensemble machine learning, random forests, neural networks, feature extraction

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323 Theoretical Analysis of Mechanical Vibration for Offshore Platform Structures

Authors: Saeed Asiri, Yousuf Z. AL-Zahrani

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A new class of support structures, called periodic structures, is introduced in this paper as a viable means for isolating the vibration transmitted from the sea waves to offshore platform structures through its legs. A passive approach to reduce transmitted vibration generated by waves is presented. The approach utilizes the property of periodic structural components that creates stop and pass bands. The stop band regions can be tailored to correspond to regions of the frequency spectra that contain harmonics of the wave frequency, attenuating the response in those regions. A periodic structural component is comprised of a repeating array of cells, which are themselves an assembly of elements. The elements may have differing material properties as well as geometric variations. For the purpose of this research, only geometric and material variations are considered and each cell is assumed to be identical. A periodic leg is designed in order to reduce transmitted vibration of sea waves. The effectiveness of the periodicity on the vibration levels of platform will be demonstrated theoretically. The theory governing the operation of this class of periodic structures is introduced using the transfer matrix method. The unique filtering characteristics of periodic structures are demonstrated as functions of their design parameters for structures with geometrical and material discontinuities; and determine the propagation factor by using the spectral finite element analysis and the effectiveness of design on the leg structure by changing the ratio of step length and area interface between the materials is demonstrated in order to find the propagation factor and frequency response.

Keywords: vibrations, periodic structures, offshore, platforms, transfer matrix method

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322 Neo-Adjuvant B-CAT Chemotherapy in Triple Negative Breast Cancer

Authors: Muneeb Nasir, Misbah Masood, Farrukh Rashid, Abubabakar Shahid

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Introduction: Neo-adjuvant chemotherapy is a potent option for triple negative breast cancer (TNBC) as these tumours lack a clearly defined therapeutic target. Several recent studies lend support that pathological complete remission (pCR) is associated with improved disease free survival (DFS) and overall survival (OS) and could be used as surrogate marker for DFS and OS in breast cancer patients. Methods: We have used a four-drug protocol in T3 and T4 TNBC patients either N+ or N- in the neo-adjuvant setting. The 15 patients enrolled in this study had a median age of 45 years. 12 patients went on to complete four planned cycles of B-CAT protocol. The chemotherapy regimen included inj. Bevacizumab 5mg/kg D1, inj. Adriamycin 50mg/m2 D1 and Docetaxel 65mg/m2 on D1. Inj. Cisplatin 60mg/m2 on D2. All patients received GCF support from D4 to D9 of each cycle. Results: Radiological assessment using ultrasound and PET-CT revealed a high percentage of responses. Radiological CR was documented in half of the patients (6/12) after four cycles. Remaining patients went on to receive 2 more cycles before undergoing radical surgery. pCR was documented in 7/12 patients and 3 more had a good partial response. The regimen was toxic and grade ¾ neutropenia was seen in 58% of patients. Four episodes of febrile neutropenia were reported and managed. Non-hematatological toxicities were common with mucositis, diarrhea, asthenia and neuropathy topping the list. Conclusion: B-CAT is a very active combination with very high pCR rates in TNBC. Toxicities though frequent, were manageable on outpatient basis. This protocol warrants further investigation.

Keywords: B-CAT:bevacizumab, cisplatin, adriamycin, taxotere, CR: complete response, pCR: pathological complete response, TNBC: triple negative breast cancer

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321 An Audit of Local Guidance Compliance For Stereotactic Core Biopsy For DCIS In The Breast Screening Programme

Authors: Aisling Eves, Andrew Pieri, Ross McLean, Nerys Forester

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Background: The breast unit local guideline recommends that 12 cores should be used in a stereotactic-guided biopsy to diagnose DCIS. Twelve cores are regarded to provide good diagnostic value without removing more breast tissue than necessary. This study aimed to determine compliance with guidelines and investigated how the number of cores impacted upon the re-excision rate and size discrepancies. Methods: This single-centre retrospective cohort study of 72 consecutive breast screened patients with <15mm DCIS on radiological report underwent stereotactic-guided core biopsy and subsequent surgical excision. Clinical, radiological, and histological data were collected over 5 years, and ASCO guidelines for margin involvement of <2mm was used to guide the need for re-excision. Results: Forty-six (63.9%) patients had <12 cores taken, and 26 (36.1%) patients had ≥12 cores taken. Only six (8.3%) patients had 12 cores taken in their stereotactic biopsy. Incomplete surgical excision was seen in 17 patients overall (23.6%), and of these patients, twelve (70.6%) had fewer than 12 cores taken (p=0.55 for the difference between groups). Mammogram and biopsy underestimated the size of the DCIS in this subgroup by a median of 15mm (range: 6-135mm). Re-excision was required in 9 patients (12.5%), and five patients (6.9%) were found to have invasive ductal carcinoma on excision (80% had <12 cores, p=0.43). Discussion: There is poor compliance with the breast unit local guidelines and higher rates of re-excision in patients who did not have ≥12 cores taken. Taking ≥12 cores resulted in fewer missed invasive cancers lower incomplete excision and re-excision rates.

Keywords: stereotactic core biopsy, DCIS, breast screening, Re-excision rates, core biopsy

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320 Role of Mismatch Repair Protein Expression in Colorectal Cancer: A Study from North India

Authors: Alka Yadav, Mayank Jain, Rajan Saxena, Niraj Kumari, Narendra Krishnani, Ashok Kumar

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Purpose: To study the mismatch repair (MMR) protein expression and its clinicopathological correlation in colorectal cancer patients in North India. Methods: A prospective study was conducted on histologically proven 52 (38 males and 14 females) patients with adenocarcinoma of colorectum. MMR protein loss was determined by using immunohistochemistry for MLH1, MSH2, PMS2 and MSH6. Results: 52 patients (38 males and 14 females) underwent resection for colorectal cancer with the median age of 52 years (16-81 years). 35% of the patients (n=18) were younger than 50 years of the age. 3 patients had associated history of malignancy in the family. 29 (56%) patients had right colon cancer, 9 (17%) left colon cancer and 14 (27%) rectal cancer. 2 patients each had synchronous and metachronous cancer. Histology revealed well-differentiated tumour in 16, moderately differentiated in 10 and poorly differentiated tumour in 26 patients. MMR protein loss was seen in 15 (29%) patients. Seven (46%) of these patients were less than 50 years of age. Combined loss of MSH2 and MSH6 was seen most commonly and it was found in 6 patients. 12 (80%) patients with MMR protein loss had tumour located proximal to the splenic flexure compared to 3 (20%) located distal to the splenic flexure. There was no difference in MMR protein loss based on patients' age, gender, degree of tumour differentiation, stage of the disease and tumour histological characteristics. Conclusions: This study revealed that there was less than 30% MMR protein loss in colorectal cancer patients. The loss was most commonly seen in right sided colon cancer than left. A larger study is further required to validate these findings.

Keywords: colorectal cancer, mismatch repair protein, immunohitochemistry, clinicopathological correlation

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319 Reducing CO2 Emission Using EDA and Weighted Sum Model in Smart Parking System

Authors: Rahman Ali, Muhammad Sajjad, Farkhund Iqbal, Muhammad Sadiq Hassan Zada, Mohammed Hussain

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Emission of Carbon Dioxide (CO2) has adversely affected the environment. One of the major sources of CO2 emission is transportation. In the last few decades, the increase in mobility of people using vehicles has enormously increased the emission of CO2 in the environment. To reduce CO2 emission, sustainable transportation system is required in which smart parking is one of the important measures that need to be established. To contribute to the issue of reducing the amount of CO2 emission, this research proposes a smart parking system. A cloud-based solution is provided to the drivers which automatically searches and recommends the most preferred parking slots. To determine preferences of the parking areas, this methodology exploits a number of unique parking features which ultimately results in the selection of a parking that leads to minimum level of CO2 emission from the current position of the vehicle. To realize the methodology, a scenario-based implementation is considered. During the implementation, a mobile application with GPS signals, vehicles with a number of vehicle features and a list of parking areas with parking features are used by sorting, multi-level filtering, exploratory data analysis (EDA, Analytical Hierarchy Process (AHP)) and weighted sum model (WSM) to rank the parking areas and recommend the drivers with top-k most preferred parking areas. In the EDA process, “2020testcar-2020-03-03”, a freely available dataset is used to estimate CO2 emission of a particular vehicle. To evaluate the system, results of the proposed system are compared with the conventional approach, which reveal that the proposed methodology supersedes the conventional one in reducing the emission of CO2 into the atmosphere.

Keywords: car parking, Co2, Co2 reduction, IoT, merge sort, number plate recognition, smart car parking

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318 Nanoparticle Emission Characteristics during Methane Pyrolysis in a Laminar Premixed Flame

Authors: Mohammad Javad Afroughi, Farjad Falahati, Larry W. Kostiuk, Jason S. Olfert

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This study investigates the physical characteristics of nanoparticles generated during pyrolysis of methane in hot products of a premixed propane-air flame. An inverted burner is designed to provide a laminar premixed propane-air flame (35 SLPM) then introduce methane co-flow to be pyrolyzed within a closed cylindrical chamber (20 cm in diameter and 68 cm in length). The formed products are discharged through an exhaust with a sampling branch to measure emission characteristics. Carbon particles are sampled with a preheated nitrogen dilution system, and the size distribution of particles formed by pyrolysis is measured by a scanning mobility particle sizer (SMPS). Dilution ratio is calculated using simultaneously measured CO2 concentrations in the exhaust products and diluted samples. Results show that particle size distribution (PSD) is strongly affected by dilution ratio and preheating temperature. PSD becomes unstable at high dilution ratios (typically above 700 times) and/or low preheating temperatures (below 40° C). At a suitable dilution ratio of 55 and preheating temperature up to 70° C, the median diameter of PSD increases from 20 to 220 nm following the introduction of 0.5 SLPM of methane to the propane-air premixed flame. Furthermore, with pyrolysis of methane, total particle number concentration and estimated total mass concentration of particles in the size range of 14 to 700 nm, increase from 1.12 to 3.90 *107 cm-3 and from 0.11 to 154 µg L-1, respectively.

Keywords: laminar premixed flame, methane pyrolysis, nanoparticle physical characteristics, particle mass concentration, particle number concentration, particle size distribution (PSD)

Procedia PDF Downloads 239