Gamma-Radiation Induced Redox Reactions and Colloidal Formation of Chromium and Cobalt Oxide Nanoparticles

The main goal of this thesis research is to develop a mechanistic understanding of radiation-induced chromium oxide and cobalt oxide nanoparticle formation in aqueous solutions containing initially dissolved metal ions. When exposed to ionizing radiation, water decomposes to form a range of chemically reactive radical and molecular products. This redox agents can readily change the oxidation state of dissolved metal ions. The solubility of a transition metal ion can vary by several orders of magnitude depending on its oxidation state and the solution pH. Thus, reactions that can alter the oxidation state of a dissolved ion can lead to the condensation of insoluble species and the formation of solid particles. The formation of Co3O4 nano-scale colloid particles by gamma irradiation of CoSO4 solutions was investigated as a function of pH, initial CoII concentration and radical scavenger environment. Particle formation was observed only in aerated solutions. Analysis of the particle formation as a function of irradiation time and information from the scavenger studies shows that the particles evolve from Co(OH)2 to CoOOH and then to Co3O4 with oxidation of Co2+ to Co3+ by OH being the most important process. Transmission electron microscopy (TEM) images show that the final particles size depend on the initial conditions of the solution. The formation of chromium oxide nanoparticles by gamma radiolysis of CrVI solutions was investigated as a function of pH, initial CrVI concentration and scavenger environment. The results show that CrVI is easily reduced to CrIII by a homogeneous aqueous reaction with eaq-, but, due to the stability of CrIII colloids, the growth of the Cr(OH)3 particles is very slow. However, after some time the Cr(OH)3 is converted to Cr2O3. Again for this system, the sizes of the particles formed depend on the solution conditions

Tutorial Dialog in an Equation Solving Intelligent Tutoring System

This thesis makes a contribution to Intelligent Tutoring Systems (ITS) architectures. A new intelligent tutoring system is presented for the domain of solving linear equations. This system is novel, because it is the first intelligent equation-solving tutor that combines a cognitive model of the domain with a model of dialog-based tutoring. The tutorial model is novel because it is based on the observation of an experienced human tutor and captures tutorial strategies specific to the domain of equation-solving. In this context, a tutorial dialog is the equivalent of breaking down problems into simpler steps and then asking new questions to the student before proceeding to the next navigational step. The resulting system, named E-tutor, was compared, via a randomized controlled experiment, to an algebra ITS similar to the“Cognitive Tutor by Carnegie Learning, Inc®. The Cognitive Tutor can provide traditional model-tracing feedback and buggy messages to students, but does not engage students in dialog. Preliminary results using a very small sample size, i.e., teaching equation solving to 15 high school students, showed that E-Tutor with dialog capabilities performed better than E-tutor without dialog. This result showed an effect size of 0.4 standard deviations for overall learning by condition. This set of preliminary results, though not statistically significant, shows promising opportunities to improve learning performance by adding tutorial dialog capabilities to ITSs. However, significant further validation is required, specifically, adding greater numbers and variations of the work to our sample size, before this approach can be deemed successful. The system is available at www.wpi.edu/~leenar/E-tutor

Epidemiology of antibiotic resistance in culture-positive hospitalized patients in selected hospitals in Khartoum, Sudan

Objective: To study the prevelence of antibiotic resistance and the prevalent bacterial isolates in hospitalized patients in Khartoum hospitals. Materials & Methods: A cross-sectional prevalence study was carried out during the period of April–November 2015 in Khartoum; 226 bacterial cultures were included. Identification of isolates using standard biochemical tests and antibiotic susceptibilities were determined using disc diffusion method. Results were interpreted according to the standards of the British society of antimicrobial chemotherapy. Results: Eight bacterial species were isolated: Staphylococcus aureus, Enterococcus faecalis, Streptococcus spp., Klebsiella pneumoniae, Pseudomonas spp., Escherichia coli, Proteus spp., and Acinetobacter spp. S. aureus was the most prevalent, the majority of which were resistant to methicillin/oxacillin (MRSA). Cultures in our study were mainly from urine (36.7%), blood samples (37.2%), and wound cultures (19%). More than 90% of the tested isolates were resistant to cefuroxime; 54% and 73.8% of Gram-positive and Gram-negative isolates, respectively, were resistant to ceftazidime. Furthermore, there was a high meropenem resistance among Gram-negative isolates tested. Multi-resistant Acinetobacter spp. as well as vancomycin-resistant S. aureus was isolated. Gram-negative isolates showed good susceptibilities to aminoglycosides as well as ciprofloxacin. However, the high resistance rate to these antibiotics was observed in Gram-positive isolates in these hospitals. Conclusion: Methicillin-resistant S. aureus was the most prevalent organism. Gramnegative isolates showed good susceptibilities to aminoglycosides and ciprofloxacin. There were high resistance rates to cefuroxime, ceftazidime, and meropenem. Five vancomycin-resistant S. aureus were identified

Concept Drift Identification using Classifier Ensemble Approach

Abstract:-In Internetworking system, the huge amount of data is scattered, generated and processed over the network. The data mining techniques are used to discover the unknown pattern from the underlying data. A traditional classification model is used to classify the data based on past labelled data. However in many current applications, data is increasing in size with fluctuating patterns. Due to this new feature may arrive in the data. It is present in many applications like sensornetwork, banking and telecommunication systems, financial domain, Electricity usage and prices based on its demand and supplyetc .Thus change in data distribution reduces the accuracy of classifying the data. It may discover some patterns as frequent while other patterns tend to disappear and wrongly classify. To mine such data distribution, traditionalclassification techniques may not be suitable as the distribution generating the items can change over time so data from the past may become irrelevant or even false for the current prediction. For handlingsuch varying pattern of data, concept drift mining approach is used to improve the accuracy of classification techniques. In this paper we have proposed ensemble approach for improving the accuracy of classifier. The ensemble classifier is applied on 3 different data sets. We investigated different features for the different chunk of data which is further given to ensemble classifier. We observed the proposed approach improves the accuracy of classifier for different chunks of data

Recent advances in technologies for developing drugs against Chlamydia pneumoniae

Peer reviewe

A collaborative expert system for group decision making in public policy

In the policy arena, there is high pressure to provide right and quick decisions for problems that are often poorly defined. There is hence an urgent need to support stakeholders in establishing a shared understanding of policy problems and to assist them in the design of potential solutions. Here we propose a formal methodology based on the construction and analysis of system maps, i.e., a graphical representation of the complex interdependencies of all relevant factors that affect the problem under study. Owing to their collaborative design, system maps provide a transparent tool with broad stakeholder acceptance to analyze ill-defined problems in a formal way. The construction of system maps involves expert elicitation to define system components, system boundaries, and interactions between system components, whereas the dynamical system behavior can be approximated by means of system dynamics. Although there is great value in the construction of the system map to enhance the understanding of the problem scenario, we consider this as an intermediate step. The final target is to present the full life-cycle of system maps and assist decision-makers in the entire decision-making process through the construction and analysis of system maps, i.e., from the understanding of the system behavior, to the definition of objectives and constraints, and finally the presentation of feasible solutions. System maps provides us with an effective framework to collect information dispersed over the experts, facilitate mediation, and analyze formally potential pathway solutions, meeting different criteria of optimality

Fracture Toughness and Micro-Strain of Y-TZP Nanoceramics at Different Sintering Temperature

الهدف من هذا البحث هو دراسة تاثير درجة حرارة التلبيد على الخواص الميكانيكية و الانفعال المرن للزركونيا المثبتة باليتريا النانوية. حيث تم تلبيد العينات المكبوسة عند درجات (1500 – 1550 – 1600م⁰) في الهواء لمدة ساعتين , ثم بعد التلبيد تم صقلها لغرض اجراء فحص الصلادة المايكروية و لفحص متانة الكسر بواسطة جهاز فكرز (من 60 كغم الى 100غم). تم استخدام جهاز المجهر الذري  لايجاد التغير في حجم و شكل الحبيبات في العينات , و تم فحصها بواسطة الاشعة السينية لتحديد نوع الطور الناتج و لتحديد قيمة الانفعال المايكروي للعينات. لقد بينت النتائج انه عند زيادة درجة التلبيد سوف يزداد الحجم الحبيبي مع زيادة الانفعال المايكروي. ان الطور السائد الناتج بعد التلبيد هو الطورالرباعي , مع زيادة ابعاد المشبك نتيجة للانفعال المرن , و مع زيادة درجة التلبيد تزداد الصلادة المايكروية مع زيادة متانة الكسر.  The objective of this research is to study the effect of sintering temperature on the mechanical properties and micro-strain of yttria tetragonal zirconia polycrystalls (Y-TZP) nanostructure.   Where green disk formed by uniaxially press, sintered at (1500 – 1550 – 1600⁰C) in air for 2hr then polished to mirror shape for fracture toughness and micro-hardness measurement by Vickers indenter at (60 kg to 100gm) loads. Atomic force microscopy (AFM) technique was use to measure the change in grain size and shape of the samples, X-ray diffraction (XRD) evaluated to identify the phases and to measure the micro-strain of the samples.          The Results show that increasing sintering temperature will increase the grain size with increasing the average of micro-strain. Tetragonal  phase is the prevailing phase with small amount of cubic phase and the amount of monoclinic phase was under detection limite after sintering but there is increas in lattice dimension according to micro-strain calculation and grinding process produce micro-strain. With increasing the sintering temperature micro-hardness and fracture toughness will increas

Puusta valmistettujen tuotteiden hiilivaraston muutoksen laskenta kasvihuonekaasuinventaariossa : Menetelmäkehitys Suomen kasvihuonekaasuinventaarioon

Tämän tutkimuksen päätavoite oli kehittää puutuotelaskentamenetelmä, jolla voidaan tuottaa estimaatit Suomen kasvihuonekaasujen inventaarioraportointiin. Laskentamenetelmän oli perustuttava ilmastosopimuksen ja Kioton pöytäkirjan osapuolikokousten päätöksiin. Tässä tutkimuksessa puutuotteilla tarkoitetaan puusta valmistettuja puolivalmisteita, joita ovat sahatavara, puulevyt, paperi ja kartonki sekä muut puolivalmisteet, kuten hirret ja puhelinpylväät. Kioton pöytäkirjan laskennassa puutuotteiden alkuperän selvittäminen oli yksi tärkeimmistä tavoitteista. Alkuperällä tarkoitetaan tässä tapauksessa sitä, onko puutuotteisiin käytetty puu peräisin Kioton pöytäkirjan aktiviteeteistä (metsänhoito, metsitys, metsänhävitys) vai näiden kolmen luokan ulkopuolisilta alueilta. Tavoitteena oli arvioida hakkuupoistumat näissä luokissa vuodesta 1990 alkaen. Tutkimuksessa tuotettiin erilaisilla laskentavaihtoehdoilla aikasarjat ilmastosopimuksen ja Kioton pöytäkirjan mukaisiin laskentoihin käyttäen tuotantoon perustuvaa laskentaa, jossa huomioidaan kotimaassa tuotetut ja vientiin menneet puutuotteet, jotka on valmistettu kotimaisesta puusta. Laskennan luotettavuutta saatiin parannettua kokoamalla vuosia 1900–1960 koskeva kansallinen aineisto sekä selvittämällä suomalaisille puutuotteille soveltuvat kansalliset hiilenmuuntokertoimet. Sahatavara, puulevyt ja puumassat (paperin ja kartongin hiilitaseiden arvioimiseksi) jaettiin laskennassa mielekkäisiin alaryhmiin, jotta puutuotteiden hiilitaseista saataisiin luotettavammat tulokset. Laskennassa käytettiin kullekin alaryhmälle sopivia hiilenmuuntokertoimia, ja kullekin puutuoteryhmälle omia kotimaisuusasteitaan. Tutkimuksen tulokset antavat tietoa siitä, kuinka puutuotteet on tarkoituksenmukaisinta laskea Suomen kasvihuonekaasuinventaariossa ottaen huomioon ilmastosopimuksen päätösten ja IPCC:n raportointiohjeiden asettamat vaatimukset.201

Endogenous erythropoietin at birth is associated with neurodevelopmental morbidity in early childhood

Background New biomarkers that predict later neurodevelopmental morbidity are needed. This study evaluated the associations between umbilical cord serum erythropoietin (us-EPO) and neurodevelopmental morbidity by the age of 2-6.5 years in a Finnish cohort. Methods This study included 878 non-anomalous children born alive in 2012 to 2016 in Helsinki University Hospitals and whose us-EPO concentration was determined at birth. Data of these children were linked to data from the Finnish Medical Birth Register and the Finnish Hospital Discharge Register. Neurodevelopmental morbidity included cerebral palsy, epilepsy, intellectual disability, autism spectrum disorder, sensorineural defects, and minor neurodevelopmental disorders. Results In the cohort including both term and preterm children, us-EPO levels correlated with gestational age (r = 0.526) and were lower in premature children. High us-EPO levels (>100 IU/l) were associated with an increased risk of severe neurodevelopmental morbidity (OR: 4.87; 95% CI: 1.05-22.58) when adjusted for the gestational age. The distribution of us-EPO levels did not differ in children with or without the later neurodevelopmental diagnosis. Conclusions Although high us-EPO concentration at birth was associated with an increased risk of neurodevelopmental morbidity in early childhood, the role of us-EPO determination in clinical use appears to be minor. Impact We determined whether endogenous umbilical cord serum erythropoietin would be a new useful biomarker to predict the risk of neurodevelopmental morbidity. This study evaluated the role of endogenous erythropoietin at birth in neurodevelopmental morbidity with a study population of good size and specific diagnoses based on data from high-quality registers. Although high umbilical cord serum erythropoietin concentration at birth was associated with an increased risk of neurodevelopmental morbidity in early childhood, the clinical value of erythropoietin determination appears to be minor.Peer reviewe